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SPECIFICATION Department:
Control Systems
Document No:
I010S
Document Title:
CONTROL PHILOSOPHY
PROJECT REFERENCE
3
Project No.: Project Location:
TS120100 Barbil, Odisha, India.
Project Title:
Iron Ore Pelletizing Plant II
Client:
Jindal Steel and Power Ltd.
PM Authorisation:
Date:
Client Authorisation:
Date:
th
13 July, 2013
APPROVALS Rev 0 1
Issue Date
Revision Description Descriptio n
16 Oct 2012 Issued for Design 20 Nov 2012 Issued for Design
Prepared Checked Disp.App Proj. App JR KT
RC RC
RC RC
TC TC
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TABLE OF CONTENTS 1.0
INTENT OF THE DOCUMENT
2.0
CONVENTIONS
3.0
IRON ORE RECEIVING & WET GRINDING SECTION- AREA 1
4.0
ADDITIVE RECEIVING AND DRY GRINDING -AREA 2
5.0
MIXING –AREA 3
6.0
BALLING – AREA 4
7.0
INDURATING – AREA 5
8.0
PRODUCT SCREENING – AREA 6
9.0
POLLUTION CONTROL – AREA 7
10.0
UTILITIES – AREA 8
11.0
CONTROL SYSTEM OVERVIEW & PHILOSOPHY
12.0
ANNEXURE I – PID LOOP LIST
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TABLE OF CONTENTS 1.0
INTENT OF THE DOCUMENT
2.0
CONVENTIONS
3.0
IRON ORE RECEIVING & WET GRINDING SECTION- AREA 1
4.0
ADDITIVE RECEIVING AND DRY GRINDING -AREA 2
5.0
MIXING –AREA 3
6.0
BALLING – AREA 4
7.0
INDURATING – AREA 5
8.0
PRODUCT SCREENING – AREA 6
9.0
POLLUTION CONTROL – AREA 7
10.0
UTILITIES – AREA 8
11.0
CONTROL SYSTEM OVERVIEW & PHILOSOPHY
12.0
ANNEXURE I – PID LOOP LIST
5
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1.0
5
INTENT OF THIS DOCUMENT
This document describes the control system for iron ore pelletizing facility, based on the Dravo Traveling Grate Process, located at the site of Jindal Steel and Power Limited (JSPL) in Barbil, Odisha, India. This plant is designated as JSPL Pellet Plant 2 and is located adjacent to the existing JSPL Pellet Plant 1. Specific vendor document for equipment/package is used as a basis to provide detailed philosophy. The pellet plant is conceived as a versatile operation capable of producing a variety of product types, as predicated by the ore supply supply and/or the consumer consumer demand. Thus, from time to time, campaigns may be run to produce varieties ranging from acid pellets to fluxed pell ets. The pellet plant conveyors and hardware will be mechanically designed to handle 4,500,000 direct reduction grade (DR-grade) ore pellets per year in 330 days of operation (7,920 scheduled hours per year), taking into account all design safety safety factors. Actual indurating capacity is dependent upon the specific ore being utilized, the type of pellets being produced, and quality specifications of the consumer. Total plant availability is dependent upon the specific operating and maintenance practice employed at the site. JSPL’s target production is 4,000,000 tonnes per per annum of fired pellets. 2.0
CONVENTIONS
The sections on control philosophy for each area include references to “Loops” with associated numbers. These loops are instrument loops identified by number on the Piping and Instrumentation Diagrams (P&IDs). 3.0
IRON ORE RECEIVING & WET GRINDING SECTION- AREA 1 3.1 Iron Ore Receiving (P&ID: R-01-1001)
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with a chute at the back end. When Bin-2 is full (‘High’ alarm), OF-14 moves ahead and the chute fitted with the shuttle car comes in line with the discharge chute of OF-13 and Bin-1 starts getting filled up. The filling of each bin will be controlled by the level transmitter ‘High’ & ‘Low’ Set points. The position for the shuttle car filling BIN-01 directly will be determined by a limit switch installed corresponding to desired position which will stop the shuttle car motor. On receipt of ‘H’ signal (70%) from Bin-01 the shuttle car starts traveling to fill Bin-02. After receipt of ‘H’ signal from any of the bins if the shuttle car fails to move to the other bin due to any reason within 2 minutes the shuttle conveyor will stop and subsequently all upstream conveyors will stop sequentially. ‘H-H’ alarm (90%) from both bin level transmitters and/or unhealthy signal from any conveyor safety switch will stop up-stream conveyors in a sequential manner. There are 2 weigh belt feeders WF-1 and WF-2 (B55201-1, 2) (Loop No: WIC-01B0107 & WIC01B0117, P&ID: R-01-1001) located under Ball Mill Feed Bins-1 & 2 respectively. The weigh belt feeders feed blended ore to respective ball mill feed conveyors BMF-1 & B MF-2 (B43002-1&2). Group start-up of weigh belt feeders and mill f eed conveyors will depend on the following factors: • • •
Healthy signal from the safety switches placed on the conveyors Ball mill (B46201 / B46202) is running Low-Low alarm not present at the respective bin.
The feed rate set point to the weigh feeders is from the Ball Mill Specific Energy Consumption (JIC01B0206, JIC-01B0506, P&ID: R-01-1002 & R-01-1005). Ball mill feed set point is based on mill specific energy, kWh/T as formulated below: Feed (TPH) =
(Mill kWh per h) / (Mill kWh per T)
Mill Specific energy will be set by an operator at 12.5 (Constant) [Refer P&ID: R-01-1001, Note-5] The action on a bin alarm of “low-low” (5%) is to stop the belt weigh feeder (B55201-1, 2) under the
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Iron ore feed size of -12mm (F100) with moisture content 8% is fed into the ball mill in a controlled rate .Water added at the ball mill inlet to cater to grinding and to maintain the consistency in percentage solids at the trommel discharge. The discharge from ball mill is pumped to a classifying Hydrocyclone for separating -70 to -75 microns fractions (P80). The oversize will be recycled to Ball Mill for further grinding. The Product will be collected from the Hydrocyclone over flow. Hydrocyclone underflow is taken as a recycle into ball mill feed, this forms the closed circuit. Required dilution water through flow control valves FV0021/FV1021 can be added to the slurry tank to maintain density of slurry to the Hydrocyclone (Loop No: FIC-B01-0020 / FIC-B01-1020, P&ID: R-01-1003 / R-01-1006) A flow transmitter FIT0037 / FIT1037 and Density meter DIT0036 / DIT1036 (Loop No: DIC-B010036 / 1036, P&ID: R-01-1003 / R-01-1006) is provided in the discharge of the slurry pumps (331.PU210/B41101-1, 2 / 3, 4) to maintain the slurry density and flow rate to the Hydrocyclone. The readings of the same will be available at the Main Automation System. A Flow control valve FCV0044 / FCV1042 located in the ball mill feed water pipe to ensure proper control on the water addition to mill (Loop No: FIC-B01-0042 / 1 040, P&ID: R-01-1002 / R-01-1005). Protective trips/alarms for the mill motor, lubrication system etc would be actuated from the Main Automation System. A local control panel monitors girth gear – pinion grease lubrication system. Main Automation System obtains only healthy and unhealthy signals from the Girth gear local control panel. However, the start/ stop command can be initiated from the Main Automation System. 3.3.2
Normal Start-up Sequence
This section describes the functional group startup sequence. If the group has an automatic start sequence, time delays between equipment will also be listed. Any group preconditions required prior to startup are also listed herein. However, interlocks required for individual or predefined groups of equipment are listed in the Interlocks section. 3.3.3
Normal Operation
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Main Automation System Control Commands to operate the equipment control system are made by an operator using the Main Automation System HMI. The Main Automation System can only operate equipment in Automatic Mode. 3.3.4
Normal Shutdown Sequence
This section describes the group shutdown sequence. If the group has an automatic shutdown sequence, time delays to allow for equipment cleanout or deceleration will also be listed. 3.3.5
Abnormal and Emergency Shutdowns
This section describes abnormal shutdown conditions caused by isolated process or equipment abnormalities or activation of individual equipment safety devices. It also describes emergency shutdowns due to automatic activation of personnel safety systems or field emergency stop pushbuttons. 3.3.6
Interlocks
The Interlocks section describes all interlocks for the individual equipment or functional group of equipment within the associated software function group. Interlock is defined herein as an input/output signal or a Main Automation System/Main Automation System internal logic condition, which automatically prevents the operation of an individual or functional group of equipment from the Plant Main Automation System HMI. When the condition of an interlock(s) is such that operation of a related piece of equipment or an equipment group is permitted, the interlock(s) is defined as being “satisfied.” Specific devices in the Interlock table may be preceded by “NOT”. This is the condition for the analog threshold (i.e. NOT Bearing Temperature High-High = Bearing Temperature is NOT ABOVE the High-High Set point). However, in the case of discrete switches the Interlock is stated from the “ON” perspective of the switch. For example the Oil Reservoir Low switch is ON when the oil level is NOT Low (fail-safe), so the required interlock in the switch being true.
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Protective Interlocks: Protective interlocks are those interlocks for the protection of the motor itself. As a result, protective interlocks apply when operating in “Automatic Mode”, “Manual Mode” and “Local Mode”. Example A protective interlock for an equipment motor would be motor bearing temperature or motor winding temperature. Machine Interlocks: Machine interlocks are those interlocks for the protection of the machine that is operating in Automatic Mode. As a result, machine interlocks apply only when operating in “Automatic Mode”. Example A machine interlock for a belt conveyor would be a belt drift switch. Operational Interlocks: Operational interlocks are those interlocks that are related to the process, but not to the equipment, that is necessary for the normal operation of the item. As a result, operational interlocks apply only when operating in “Automatic Mode”. Example: An operational interlock would be downstream equipment running. 3.3.7
Overview
The mill plant incorporates the following features: •
Feed system (Described in section 3.1)
•
Ball mill
•
Hydrocyclone
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In operation, pressurized slurry is fed to the Hydro cyclone and the centrifugal force generated causes the heavier suspended solids to move toward the wall while the radial velocity forces the liquid and lighter gravity solids to move inward toward the central axis. Primary and secondary vortex develops. The primary vortex carries the solids to the apex. The apex orifice permits the heavier solids and a small amount of the liquor to be discharged. A secondary developing vortex carries the cleaned primary liquid (liquor) and light gravity solids out through the Vortex Finder Tube. The performance of the hydro cyclone is based on the particle size distribution of the cyclone overflow. The underflow slurry from the hydro cyclone is fed in to the ball mill. The hydro cyclone overflow is fed to the Thickener Feed Well by gravity. 3.3.7.3
Product Slurry System
Each grinding mill will have a dedicated mill discharge slurry pump tank which collects the ground iron ore slurry from the mill. Each slurry pump tank with conical bottom, is of approximately 50 m3 capacity. The tank base will preferably be above grade level. Water addition to the Ball Mill Slurry Tank is to control the Density of the slurry being fed to the Hydro Cyclone which is monitored by density meter at the slurry pump discharge. This is controlled by a Control Valve in the Water Addition Line to the slurry tank. Slurry Pumps are equipped the Variable speed drive to maintain consistent pressure in the Hydro Cyclone for better classification and the slurry tank is equipped with Level transmitter to maintain level in tank. 3.3.8
Operation Philosophy and Plant Sequencing
Starting of the mill system is divided into a number of groups. Each drive/ equipment/ Valves in a particular group has a specified sequence of operation. Each group in itself has a specified sequence of operation during start and stop. This means that no equipment can be started before the subsequent equipment has been started. Inversely, stop of any equipment will cause the stop of the preceding equipment, unless until specified herein. This section outlines the division of groups; the basic terminology used in numbering of the groups, sequential Interlocks between groups and between equipment/ drives/ Valves in every particular group.
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Hydro cyclone and Mill discharge tank group, the mill dr ive has to be started immediately). f.
After ensuring that the utilities are ready the operator initiates the starting of the plant. 3.3.9
Equipment Grouping
The various sections of the wet grinding circuit are assigned group numbers to assist the definition of discrete areas. Groups can be started up individually in preparation for overall plant start-up. These numbers will also be used for plant start-up and commissioning planning activities. Details of the groups are included in the relevant sections. The total process is broken down into four discrete groups to allow for easy description of the facilities. These are as follows: Group 1 – Slurry Classification Group 2 – Ball mill Lubrication Group 3 – Ball Mill Group 4 – Ball mill Feed 3.3.10 Slurry Classification – Group-1 (P&ID: R-01-1003, R-01-1004, R-01-1006, R-011007) 3.3.10.1 Group description:
The ground product from the ball mill discharges into the slurry tank (331. TK200/B35101-1).Slurry tank is provided with a level transmitter LT0023 to monitor and maintain the level with the slurry pump speed control. Pair of slurry pumps (331.PU210/331.PU220/B41101-1, 2), (one operating and the other stand by) are located adjacent to the tank transport the slurry to the Hydro cyclones. Both slurry pumps are provided with Variable frequency Drive (VFD). A ‘low’ level in the tank (331.TK200/B35101-1), (LAL0023 set at 20%) inhibits the starting of the
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3.3.10.2 Group-1 Equipment summary:
The operator can select only one slurry pump at any point of time. Selection of a pump would automatically de-select the other pump from operation. By default slurry pump (331.PU210/B41101-1) is selected for operation. a.
Suction and Discharge valves (XV0025)for(331 PU210/B41101-1)
b.
Suction and Discharge valves (XV0024)for(331 PU220/B41101-2)
c.
Hydro cyclone feed pumps (331.PU210/331.PU220/B41101-1,2) 3.3.10.3 Group-1 starting sequence:
The SCG group is a single drive group – slurry pumps. By default (331. PU210 /B41101-1) pump is selected for operation. A start command to the SCG group starts the selected pump (331.PU210/331.PU220/B41101-1, 2). a. Open discharge knife gate valve XV0034/0035 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2). b. Open suction knife gate valve XV0025/0024 with respect to the selected pump (331.PU210/B41101-1) & (331.PU220/B41101-2). c.
Start the slurry pump (331.PU210/B41101-1) & (331.PU220/B41101-2).
It will be the responsibility of the Control room operator to confirm from the field technician that the gland seal water line valve of the selected pump is open and drain valves of the selected pump are closed and stand by pump is open before embarking a start command. A knife gate valves is provided at the discharge of the pumps to isolate the non-operating pump. 3.3.10.4 Group-1 Starting interlocks:
The following general interlocks are valid for starting SCG Group. a. A level ‘low’ alarm LAL0023 (set at 30%) on the tank (331.TK200/B35101-inhibits starting of the selected slurry pump.
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3.3.11
5
Ball Mill Lubrication – Group 2
This group is divided into following functional groups for easy operation and logical control. 1. Ball Mill Main Lubrication system Group – 2A 2. Main Gearbox Lubrication system Group – 2B 3.3.11.1 Ball Mill Main Lubrication system Group – 2A (P&ID: R-01-1009, R-01-1010) 3.3.11.1.1
Group Description:
The mill lubrication system (331.LQ110) consists of 3 parts: •
Reservoir assembly and oil conditioning circuit;
•
HP hydrostatic bearings lube circuit;
•
Pinion bearings LP lube circuit.
Reservoir Assembly & Oil Conditioning Capacity of the Reservoir is 2310 litres. Tank utilises the drain lines from the bearing housings to return the "dirty hot oil" back to tank by gravity. This passes through a basket strainer which is accessible through a hinged inspection door, f or on-line inspection and cleaning. The sump tank is a 3 compartment design, 1.
Return oil
2.
Settling
3.
Clean compartments.
The clean compartment is approx. 710 litres (3 minutes retention) and the balance 1600 litres in the dirty side (6 minutes retention). The correct oil temperature in the sump tank is maintained by 3 kW heater elements (3 Nos), monitored by Temperature transmitter (TT4033). Heaters operate
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(DPIT4023),which indicates to "change-over” and clean filter unit on-line, thereafter, allowing the artisan to isolate the clogged filter housing ( close both butterfly valves ) and to replace t he clogged filter element with a new unit, resetting the visual indicator, re-opening the isolating butterfly valves after completion, bleeding and equalising the filter housing pressure, which is now ready for use. A Manual valve Controls the water flow rate through the cooler, maintaining a constant oil temperature exiting the cooler of 47°C. Temperature gauges (TG4022) before and after(TG4006) the cooler give visual indication of the water and oil temperature across the cooler. The temperature transmitter (TT4008) fitted to the cooler oil exit line, interlocked to raise an alarm if the 0 oil Temperature exceeds 52 C. The conditioned oil (clean & cool oil) exits the cooler and a bleed line return back to the sump tank clean compartment (414 lpm). Clean compartment oil level and temperatures (level LT4038> 90% 0 and oil temp TT4039> 38 C) shall meet to start the HP pumps. The conditioning pump should run continuously, even when the mill is stopped. High Pressure Hydrostatic Oil Lube The HP oil is pumped to the mill bearings via a 4 port flow divider, as follows: FE (Feed End) bearing at 118 lpm; 59 lpm per pocket DE (Discharge End) bearing at 118 lpm; 59 l pm per pocket HP Pressure gauges, HP pressure transmitters (PT 4050/ 53/ 56/ 59), HP flow transmitter (FIT4038) exist to monitor and inter-locked. The oil flow rates are balanced using rotary geared flow divider to achieve the correct flow rates to the various bearing pockets. The HP tandem gear pumps HP 01 /02 (One Working & One Standby) are isolated from the sump tank by ball valves, and protected against over-pressure by an individual pressure relief valve, set at 103 bar. Non return and ball valves isolate the pump feed lines, and a pressure gauge, oil flow transmitter are fitted for visual and MAIN AUTOMATION SYSTEM interlocking for HP system pressure. The 2750 kW TEFC mill main motors will be tripped if the pressure drops below 25 bar or oil flow drops <180lpm. Each bearing pocket is fed by an independent HP lube line at 59 lpm each and 100 bar, monitored & inter-locked by pressure gauges and pressure transmitters (PT). Two Nos in-line 54litre bladder type accumulators are fitted to the HP circuit to store oil under pressure in the event of a power failure, discharging oil through the flow divider at a reduced rate for 10 seconds until the
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3.3.11.1.3
5
Group 2A Start sequence
Start command of the Group 2A initiate the following sequence a.
Start heater HE 01
b.
Start heater HE 02
c.
Start heater HE 03 0
Note: Start the above sequence if the oil t emperature is <38 C. d.
Start the LP pump, either LP01 or LP02
e.
Start the HP pump, either HP01 or HP02 3.3.11.1.4
Group 2A Starting interlock
This group can start provided that the following conditions are satisfied a. Settling compartment low level LT4032 25% alarm is false for starting pump LP01 or LP02. b. Clean compartment low level LT4038 25% alarm is false for starting pump HP01 or HP02. c.
0
Reservoir Oil temperature (TT4033) <38 C is false for starting Pump. 3.3.11.1.5
Group 2A Running interlock
This group can run successful provided the following conditions are satisfied a. Settling compartment low-low level alarm false LT 4032 15% for pump LP01 or LP02 b. Clean compartment low-low level alarm false LT 4038 15% for pump HP01 or HP02. 0
c. Settling compartment temperature high-high alarm false TT4033> 62 C for running pump LP01 or LP02 0
d. Clean compartment temperature high-high alarm false TT4039>52 C for running HP01 or
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d.
Stop mill main motor.
e.
Stop the running HP pump, either HP01 or HP02
f.
Stop the running LP pump, either LP01 or LP02
5
3.3.11.2 Main Gearbox Lubrication system Group – 2B (R-01-1011, R-01-1012)
The ball mill main gear reducer is lubri cated utilizing a forced lubrication system. The reducer lube system 331.LQ145 contains an oil reservoir. Two oil-circulating pumps 331.GB 01/02 (one working + one standby) are utilized for oil circulation inside the reducer. An oil-water cooler is provided in the downstream to cool the oil before entering the main reservoir. The pressure of oil to the gearbox lubrication system and the oil circulation pump discharge line will be monitored by the pressure switches PSL4081. TemperatureTG4080 and pressure gauges PG4083 are provided in the line for local display. The discharge piping of the pump is connected to a differential pressure switch DPSH4084 monitors the pressure drop across the filter unit. The switch provides an input to the control system to alarm on high-pressure drop across the filter alerting the operator to change the filter. The pumps used for oil recirculation, in case failure of main pump auxiliary shall be manually started by the standby pump and will trip the working pump by the low pressure switch PSL is activated will trip the oil pump. 3.3.13
Ball Mill Group – 3 (P&ID: R-01-1002, R-01-1005, R-01-1010, R-01-1012)
3.3.12.1 Group description:
Ground ore from the Ball mill (331.BM100/B46201) discharge to the tank (331.TK200/B35101-1) and pumped through slurry pumps (331.PU210/B41101-1) to the hydro cyclone cluster (331.HN300/B45801-1, 2, 3, 4) for classification. Ball mill Inching Mode It is to be noted that inching drive engage or disengage status has also to be monitored locally. A
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pulses are complete, i.e. 7 pulses, the Main Automation System will de-energise the pump solenoid valve and the system is put on PAUS E for a set time period (10 minutes). The above cycle will be repeated as long as the mill runs. The indicator pin will not activate the limit switches if: •
no grease flow to the nozzles occurs
•
the nozzles are blocked
•
the pipeline is broken / blocked
•
the distributor and/or limit switch is faulty
•
the grease strainer is blocked
The air pressure switch PSL4062 will fail to signal the Main Automation System if the 2/2 way solenoid valve is faulty, or if the plant air pressure is low or off line. The pressure gauge gives visual indication of the system air & grease pressure. The pump should trip if no pulses are generated from the distributors, or the air pressure switches are not activated. The mill should then also trip. 3.3.12.4 Group 3 starting Sequence:
Start command of the Group 3 initiate t he following sequence a.
Start Lube System 331.LQ110
b.
Start Ball mill main motors 331. MD 135 & 140.
c.
Start the Grease spray system 331.GS137.
d.
Start Reducer Lube system 331.LQ145 3.3.12.6 Group 3 starting interlocks:
The ball mill 331.BM100 can start if the following conditions are met: 0
Pinion bearing temperature TI0018 ‘high’ alarm not true (Set at 80 C)
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pressure ‘low low’ alarm <25bar PT is not true. •
Lubrication Oil flow ‘low low’ alarm FT4048 (<180lpm) on the low pressure oil line is not true
•
Lubrication Oil flow ‘low low’ alarm FT4014/16/18/20 (<3lpm) on the high pressure oil line is not true
•
Pinion bearing temperature TI0018 ‘high high’ alarm not true (high-high alarm set at 75 C)
•
Feed end trunnion bearing temperature alarm TI0011 ‘high high’ alarm not true (high-high 0 alarm set at 65 C)
•
Discharge end trunnion bearing temperature TI0019 ‘high high’ alarm not true (high-high 0 alarm set at 65 C)
•
Mill main gearbox lubrication system 331.LQ145 run feedback healthy.
•
Motor bearing temperature TI0004/0014 ‘high high’ alarm not true (high-high alarm set at 0 65 C)
•
Motor winding temperature ‘high high’ TI0006/0012 alarm not true (high-high alarm set at 0 65 C)
•
Grease spray lubrication system healthy. The ball mill drive shall trip, if the panel fault indication is true during the delay timer of 1200seconds
•
If Mill discharge tank level LAHH0023 ‘high high’ alarm > 90% mill trips.
•
Hydro Cyclone slurry feed pumps (331.PU210/B41101-2)(331.PU220/B41101-1) run feedback healthy.
0
3.3.12.7 Grinding section stopping sequence
A stop command to Ball mill Group initiates the stopping of the ball mill main drive 331.MD 135/140 followed by the grease spray system within 2seconds (set during Commissioning).
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Mill operation with high solid percentage by weight than that recommended and a subsequent emergency shutdown. The permanent remedy for case one would be to feed clean ore in to t he mill. In both cases jamming could possibly be cleared by pressurized fresh water into the trommel screen and carefully extracting with proper tools from the discharge of the mill. If needed, stop the mill operation to clear the jam. 3.3.13.3 Integrated Start Sequence
In summary the system is started with t he following sequence. • •
Start the Group 1 Start the Group 2
•
Start the Group 3
•
Start the Group 4
•
Put the liquor flow controllers in to cascade Control. 3.3.14
Integrated Stop Sequence
In summary the system is stopped with the fol lowing sequence. • • •
Put the liquor flow controllers in to Auto mode to maintain their current set points Stop the Group 4 Wait for the mill to empty of solids
•
Stop the Group 3 Stop mill main drives Set the liquor flow rates to low values Wait for the mill discharge tank to empty of solids
•
Flushing the mill discharge slurry transfer pipe
•
Close the water flow control valves
• • •
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Mill discharge pumps speed would come to a preset value (Say 50%) if the mill discharge tank level reaches Low-Low (30%). 3.3.14.2 Failure of main bearing lubrication system
In this instance, a number of simultaneous interlock actions need to occur. Those include immediately. Failure of mill main bearing lubrication system will stop the mill main motor. Mill feed system (apron feeder & mill feed conveyor) trips immediately if mill main motor stops/trips. Mill water addition controls automatically with the ratio control. Speed of mill discharge pumps would come to a preset value if the mill discharge slurry tank level reaches Low-Low (30%). 3.3.14.3 Failure of Gearbox lubrication system
In this instance, the simultaneous interlock actions need to occur. Those include immediately. Mill main motor stops if the gearbox lubrication system is not resorted within 300 seconds from the fault occurred. 3.3.14.4 Failure of Grease Spray system
In this instance, the simultaneous interlock actions need to occur. Those include immediately. Mill main motor stops if the grease spray system is not resorted within 1200 seconds from the fault occurred. 3.3.14.5 Failure of mill discharge slurry pump
In this instance, a number of simultaneous interlock actions need to occur. Those include immediately.
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started and stopped and the rakes raised and lowered via pushbuttons on the front of the panel. The panel displays all of the alarms as well as the main process signals, viz: Torque. 3.4.1
Principle of Operation
Feed slurry enters the thickener from the t op via a feed pipe, and is discharged tangentially into the feed well. The slurry is diluted with filtrate (From Filtrate tank) and a chemical agent (a poly electrolyte) is added to bind solid particles to form suitably large and stable flocs that settle under gravitational forces. The flocculated slurry settles over a bed with a well-defined interface with clarified water above it. Clarified water flows to a peripheral collection launder at the top of the thickener and finally flow into the process water tank and again re-circulated as process water. Rake arms fastened to the drive shaft coupled with gear box, scrape the precipitated and deposited sludge towards to the centre of thickener bottom cone. Concentrated Sludge is withdrawn from central underflow nozzle located at base of the thickener and then pumped to the slurry holding tanks (B36101-1&2). 3.4.2
Control Logic for Thickener Local Control Panel
The main controls for the Thickener are as follows: 1.
Manually Start or Stop the Hydraulic power pack Electric motor through local control panel.
2.
Manually raise and lower the rake base.
3.
Rake raising and lowering through Auto mode.
4.
Manual trip Reset.
5.
Selection of operation (Auto/Manual operation) through selector switch.
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3.4.2.2
5
Auto operation
1. Auto Mode shall be selected by selector switch. 2. The Hydraulic Power pack electric motor shall be manually started. The motor shall start only if oil level is just above the specified level in the power pack and pressure switch has not exceeded maximum set pressure (95%). 3. If torque is less than 60% of the set pressure in the pressure transmitter, rake shall rotate at the lower most position and lower limit switch shall turn NC. 4. Accordingly indication shows as ‘Rake is fully lowered’. 5. Once torque reaches to 60 % or more of the preset pressure transmitter reading, rake shall raise automatically and will be held at the position so that pressure drops to 60 % of the set pressure. In any case if rake pressure reaches 95% of the set pressure, pressure switch shall be activated and the electric motor turns OFF. 6. If the rake lift carriage reaches the maximum level and still the pressure shows more than 95%, the electric motor shall turn OFF ( Upper limit switch turn to NC). 7. Accordingly indication shows as ‘Rake is fully raised’. 8. After lifting, if pressure drops to less than 40% of set pressure, rake shall lower automatically by timer circuit relay. Rake shall lower every 180 sec. interval and spike of 2 sec ON, process shall be repeated till this reaches the lower m ost position. 9. When oil level reaches the low level in the hydraulic power pack or pressure switch experiences maximum pressure (95%) or more than 60% of pre set pressure governed by the pressure transmitter, the Hooter siren turns ON.
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d) Rake fully LOWERED e) Trip RE-SET. f)
Lamp TEST.
g) Emergency STOP. h) Selector switch (Manual/Auto Mode) i)
Duel set controller (Micro process based).
j)
Hooter 3.4.2.5
Feed back to Main Automation System (Potential free contacts)
a. Pressure transmitter/Torque transducer (4 to 20 mA) b. Rake Fully lowered. c.
Rake fully raised.
d. Hydraulic oil level-Low trip. e. High torque trip (Pressure switch). f.
Hydraulic Power pack Motor ON.
g. Hydraulic Power pack Motor TRIP. Note:
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is pre calculated. Dosing Tank Volume above Low level (1-FDS-LS-04) is slightly more than this Pre calculated Volume (Effective Volume). Hence there i s no possibility of overflow. When the preparation tank (1-FDS-PRT-01) gets emptied, this signal is transferred to panel by level switch (1-FDS-LS-03) and the Transfer Pump stops (1 - FDS - TP – 01). Simultaneously, water inlet solenoid valve (1-FDS-SOV-01) actuates to open & allow water inside preparation tank (1-FDS-PRT-01). When the water just submerges agitator blades, level switch (1-FDS-LS-02) gives signal again to panel, which in turn starts Screw feeder (1-FDS-SF-01) and agitator (1-FDSAG-01). Screw feeder is allowed to operate only for few seconds thro timer (T2) to allow just enough quantity of flocculent powder required for preparing fresh batch of solution at 0.25% concentration. It will be automatically stopped through Timer. It will also invariably stop at high level (1-FDS-LS01), overriding the timer as a safety interlock, depending on the status. The water inlet to the preparation tank stops when the high level (1-FDS-LS-01) is reached. Agitator (1-FDS-AG-01) continues to mix water and powder to make homogeneous solution and stops when solution is transferred to dosing tank. The whole cycle repeats when the dosing tank level hits low level again. The safety interlock is provided, in case the level goes further low (very low) (1-FDS-LS-05) in dosing tank (approximately 50mm. lower than low level), very low level switch is actuated, trips the dosing pump (1-FDS-DP-01) In such conditions, manual building up of level in dosing tank needs to be done, till very low level signal goes off. The auto manual switch is provided on panel which enables following operations manually provided the very low dosing tank level alarm is not actuated. 1. Transfer valve operation 2. Agitator operation
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adjusted by the operator to re-establish the solids balance. The variable speed control will only be used for small adjustments. The operator may also increase the solids flow to the upstream ball mills to balance the solids into and out of the thickener. If there are large changes in the flow of solids to the thickener, then the thickener underflow will be recycled until the desired density has been re-established. One of the thickener underflow pumps may be shutdown if the one of the upstream ball mills is shutdown. The flow and density instruments on the thickener underflow pumps allow operators to compute the mass flow from the thickener. Once equilibrium is reached in the thickener, the underflow pump speed may be adjusted to yield the same mass flow to the distributor as the new solids feeding the thickener. The primary source of new solids enters the thickener from the cyclone overflow. 3.6 Thickener Overflow Water handling
Overflow from the thickener goes to Process Water sump (B15701) fitted with pumps (B41105-1, 2, 3). Two pumps would be in operating condition and 1 pump will be standby. The process water sump level controller (Loop No: LIC-01B-0804, P&ID: R-01-1023) will control makeup water addition through LV-01B0804A in case of low level of the sump or divert water to Blow down through LV-01B0804B in case of High High level of the sump. At Low Low level of the sump, process water pumps will stop. 3.7 Slurry Holding tanks
Two Dart Valves (B48201-1, 2) direct the thickener underflow slurry to Slurry holding tanks. The dart valves are operated manually from Main Automation System. Operator will allow the Dart valves to fill one Slurry Holding Tank at a time. The third dart valve is for future. Agitators (B39102-1, 2) are fitted to keep the slurry in suspension in the Slurry Holding Tanks. Slurry level (LIT-01B1304 and LIT-01B1305) should be maintained to keep the agitator below slurry level.
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• • • • • • • • • • • • •
5
Low pressure closing High pressure closing Feed - filtration Membrane compression Air through blow Top blow High pressure drainage Cake chute doors opening Filter opening – cake discharge Cloth vibration (only if required) Cake chute doors closing Cloth washing with vibrations Waiting for next cycle to commence These individual steps are generally described as follows – reference is also made to the valve sequence diagram. 3.9.1
Low pressure closing
The cycle begins with filter closing where the low-pressure high-capacity hydraulic pump is started and oil is directed by appropriate valves to retract the cylinder rods. This pump actually consists of multiple pumps mounted on a common shaft. Each pump operating one cylinder to ensure equal extension and retraction speed of all cylinders to maintain parallel movement of the pressure piece and filter plates. When the movable head reached the inner closed position indicated by proximity switches the filter Low Pressure is closed. 3.9.2
High pressure Closing
When the filter has reached the low pressure closed position, the step high pressure closing will commence. The hydraulic high pressure pump will create the required pressure to retract the cylinder rods a little bit further to accomplish compressive closing. High pressure closing pressure is
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Filtration continues for the timed period, or by using derivative calculation algorithm. The feed pump then stops and feed valve V1 closes. 3.9.4
Membrane Compression
The membrane air evacuation valve (V10) closes and the membrane compression air feed valve (V7) opens to inflate the membranes. The primary membrane compression step continues for the timed period. 3.9.5
Air Through Blow
The filtrate valve V3 (V3, V12 and V13 on VPA 20 size filters) closes, air valve V5 opens and air is entering into the filter via two of the side channels and further into the surface of the membrane plates. The air has to pass through the filter cake forcing the water around the particles, out on the drainage surface on the filter plates, and out again of t he filter through the two filtr ate ports. The membranes are kept inflated with a higher pressure than the air through blow pressure during the complete step to compensate for the reduction in the filter cake volume as the moisture is displaced. To secure a higher pressure behind the membranes during the air through blow, the valve V11 opens for booster air to pressurize the membranes at the same time as valve V5 opens for air through-blow. The booster air is delivered from a booster air compressor. The procedure described above will prevent the filter cake from cracking and consequently minimize the air consumption. The air through-blow step continues for the timed period and then valve V5 is closed.
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The two chute doors open, operated by hydraulic cylinders. Proximity switches indicate when the both doors are in open position. 3.9.9
Filter Opening cake discharge
The relevant hydraulic system valves are activated and the low pressure high capacity pumps extend the cylinders, pushing the movable head open. The filter plates are connected together to the movable head by a link system so as the movable head starts to move the plate pack is opened according to the concertina style allowing the cake to fall from the filter by gravity in the chambers one by one. When the movable head reached the outer limit of its travel indicated by proximity switches the filter is open. 3.9.10
Cloth Vibration
When the machine is in open position the weight will be checked. If the weight is above maximum allowed empty weight, the motor vibrators will start and run for short timed period to vibrate the filter cloths and to ensure that all cakes are removed from the filter cloths. If the empty weight is too high after the automatically repeated vibrations, the machine will stop. An alarm will follow which is visible on the screen and the remaining weight needs to be removed manually by further vibrations or washing. 3.9.11
Cake Chute Doors Closing
The two chute doors operated by hydraulic cylinders close. Proximity switches indicate
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Automatic Cycle Steps Schematic
5
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The VPA-press filter control system consists mainly of the following items: Main control cabinet, -K1 containing PLC, Industrial-PC and MCC functions, (designed to be installed on the filter platform). Pneumatic valve control, -PV1-2, (designed to be installed on t he filter platform). Hydraulic control, -HV1 the hydraulic junction box, (preinstalled on the h ydraulic unit). Weight system with 4 load cells and a weight central. 3.10.1
Description
The VPA-press filter is operated from the Industrial PC screen on the main control cabinet -K1 located on the filter platform. The industrial PC is connected to a PLC which handles the control logics. The VPA-press filter can be operated either in Automatic, Semi-automatic or Manually. In ‘AUTO’ the VPA-press filter operates automatically by the programmed sequence. In ‘SEMI-AUTOMATIC the filter is operated step by step through the sequence and in ‘MANUAL’ some of the filter functions can be manually operated from th e monitor. All process specific Data & Parameters can be set and adjusted in the Settings-menu. Statistics, like Cycle time, Press weight etc. is presented on the Statistics-menu. Alarm & Fault handling is implemented in the operators’ panel; each alarm will be displayed with text, status, date and time in t he Alarm-menu. The main power supply are connected to the Main control cabinet, all other supply and control voltages are created internally by use of transformers and distributed to all other different units. The cabinet are placed on rubber dampers to eliminate vibrations from the environment. The process air supply will only be connected to one point at the Pneumatic control panel, -PV1, that together with –PV2 controls all pneumatic process valves located around the press filter.
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Start order Slurry pump Start order Wash water pump Conveyor Increase speed order
5
Control Room Emergency Stop Slurry tank OK = Tank level OK and/or Density OK Dry Air OK = Pressure OK or Flow OK Wash Water OK = Tank level, or Pressure or Flow OK Slurry Pump is running, acknowledge signal Slurry Pump Fault Wash water pump is running, acknowledge signal Wash water Fault Conveyor is running, acknowledge signal Conveyor Fault
3.10.2.2 Remote control interface
The VPA Press filter can be Started & Stopped from Main Automation System, (i.e. an overriding computer). Following signals will be exchanged between the Metso VPA Press filter control system and customer overriding control: From Metso JSPL Remote mode is selected
From JSPL Metso Run/Stop order, (pulse, toggle Run and Stop)
VPA in operation VPA No Fault Completed press cycle, (pulse) In Neutral In Parking
To Neutral, (pulse) To Parking, (pulse)
→
3.11
→
Filter cake and Filtrate handling
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High Pressure water sprays are also used to clean the cloth w hen the filter frames are opened. There are 4 air compressors feeding 6 Filter Presses. The Filter Cake drops on the Filter Cake Conveyor (FC-11A, B, C, D, E & F) (B43010-1, 2, 3, 4, 5, 6) and is transported to common conveyor FC-12 (B43015). From here the filter cake will travel over conveyors FC- 13, 14, 15 & 16. Individual start-up of Filter cake collecting conveyors (FC-11A to F) and Filter cake transport conveyors FC-12, 13, 14, 15 & 16 will depend on healthy signal from the safety switches placed on the conveyors. Group start of FC-12, 13, 14, 15 & 16 will depend on the low level signal from level transmitters placed over filter cake storage bins (43502-1,2). Low signal from b in level transmitters will start F C16 first then filter cake conveyors FC-15, 14, 13 & 12 in a sequential manner provided there is healthy signal from safety switches on these conveyors. The Filter cake conveyor plow (B48005) is lowered to the conveyor in order to fill Iron ore filter cake storage bin-2 (B43502-2). Plow is equipped with two position switches, up and down. They signal the DCS which indicates to the control room operator the position of the plow. The plow is operated in manual mode; the operator raises and lowers the plow to suit. Full (High, High) bin will cause its plow to raise by the operator manually. HH alarm from both bin level transmitters and unhealthy signal from any conveyor safety switch will stop up-stream conveyors in a sequential manner. The Filtrate and Wash Water Tank (B35104) has two variable speed pumps (B41104-1, 2) to move the filtrate back to the Thickener. If the Filtrate level gets below the set point of LIT-01B1801A, then makeup water enters through LV-01AB1801. Level controller (Loop No: LIC-01B1801B, P&ID: R-01-1019) controls the speed of the Filtrate Pumps (B41104-1, 2).
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Group start up will depend on the level signal from level transmitters placed over bins. Low (20%) signal from bin level transmitters will start shuttle conveyor AF-16 first then additive feed conveyors AF-15 in a sequential manner provided there is healthy signal from safety switches of these conveyors. The Additive feed bin reversing shuttle conveyor AF-16 feeds the Lime stone feed bin (B16207) and Coal feed bin (B16205) depending on the high level signal from level transmitters LIT 2212 & 2213 placed at the bins. The position limit switch (ZS 0132 & ZS 0134) placed suitably for lime stone bin and coal bin positions will allow the shuttle car to stop over the respective bins in order to achieve un-interrupted filling of the bins. When the limestone bin (B16207) and coal bin (B 16205) level reaches the ‘High’ (70%) level (LAH02B2212 and LAH-02B2213) a light will blink at the filling location to warn operators that the bin is nearly full. If the level in both the bins should continue to rise to High, High (95%) the feed belt and feed shuttle conveyor will stop. Lime stone feed bin and Coal feed bin are equipped with individual weigh belt feeders (B43119 & B43068). Belt feeders discharge material to conveyors AMF-11 (B43079) at a controlled rate, set by the operator (Loop No: WIC - 2215 & 2216, P&ID: R-02-1001) for a capacity which is compatible with the Mill grinding capacity for that particular additive. Once the system is started, operator controls the respective belt feeder speed to obtain the desired set point as mentioned below: Low-Low (5%) bin level will stop the Weigh Belt Feeders LSF-11, CF-11 and subsequently additive mill feed conveyor AMF-11. The receiving rates for coal (10% H2O) and Lime stone (8% H2O) to the feed bins are:
Coal: Lime Stone:
Operating - TPH 100 100
Design - TPH 100 100
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of 1% at a combined Bond Work Index of 16 KWH/MT. Hot Air Generator Supplies hot air to the mill which will dry the limestone-Anthracite coal mixture during grinding. Mill exhaust Gases are vented through a dynamic Classifier which recycles coarser particles back to the mill through a flap valve and an air slide. Ground product is collected in a cyclone and a bag filter placed after the dynamic Classifier. In this system, air flow is induced by two fans, mill ID fan and filter ID fan. The clean air from Bag filter shall be released to atmosphere through a stack. Product collected by the cyclone and bag filter is transferred to a product bin which is located inside mixer building. 4.2.2
Normal Start-up Sequence This section describes the functional group’s start-up sequence. If the group has an automatic start sequence, time delays between equipment will also be listed. Any group preconditions required prior to start-up are also listed herein. However, interlocks required for individual or predefined groups of equipment are listed in the Interlocks section.
4.2.4
Normal Operation This section describes the functional group’s normal operation, including operator functions. There are three modes of operation, as described below: Automatic: “Automatic” mode is when functional groups are controlled automatically and in sequence by the control system. A functional group is a set of items such as motors, valves, etc. which are started by a single operator action when it is in Automatic Mode. All Protective, Safety, Machine, Operational and Start Interlocks must be met in order to operate. Manual: “Manual” mode is when items such as motors, valves, etc. are con-trolled individually by the operator using the control system. Functional groups have no meaning in Manual Mode. All Protective, Safety, and Start Interlocks must be met in order to operate. Local: “Local” mode is when items such as motors, valves, etc. are controlled individually in the field, usually by local pushbutton stations located at the item. Functional groups have no meaning in Local Mode. Since the operator interface in Local Mode is often physical devices rather than a
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input/output signal or a Main Automation System/Main Automation System internal logic condition, which automatically prevents the operation of an individual or functional group of equipment from the Plant MAIN AUTOMATION SYSTEM HMI. When the condition of an interlock(s) is such that operation of a related piece of equipment or an equipment group is permitted, the interlock(s) is defined as being “satisfied.” Specific devices in the Interlock table may be preceded by “NOT”. This is the condition for the analog threshold (i.e. NOT Bearing Temperature High-High = Bearing Temperature is NOT ABOVE the High-High Set point). However, in the case of discrete switches the Interlock is stated from the “ON” perspective of the switch. For example the Oil Reservoir Low switch is ON when the oil level is NOT Low (fail-safe), so the required interlock is the switch being true Interlocks consist of five types and are described in detail below: Safety interlocks: Safety interlocks are those interlocks which prevent damage to that associated piece of equipment. As a result, safety interlocks apply when operating in “Automatic Mode”, “Manual Mode” and “Local Mode”. Example Safety interlock for a fan or pump would be “no high-high bearing temperature.” Safety interlocks for every motor will also include the “MCC/motor ready” signal and receipt of a run confirmation from the motor contactor after a run command is sent. These interlocks apply to all motors and are not listed in the interlock table for this reason. Start interlocks: Start interlocks are those interlocks necessary “ONLY” for starting the machine. As soon as the motor is running the start interlock has no influence. As a result, start interlocks apply when operating in “Automatic Mode”, “Manual Mode” and “Local Mode”. Example A start interlock for a fixed speed fan with automatic damper would be that the “damper be closed” (limit switch or position transmitter) prior to starting. Protective Interlocks: Protective interlocks are those interlocks for the protection of the motor itself. As a result, protective interlocks apply when operating in “Automatic Mode”, “Manual Mode” and “Local Mode”.
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Dynamic Classifier (SEPAX) Cyclone Bag Filter ID Fans. 4.2.7.1 Ball mill Size reduction of Limestone-Anthracite coal mixture is carried out in Ball mill .The Gas-Solid mixture is swept to Dynamic Classifier after grinding. Temperature Scanner at the feed end and discharge end measures the inlet and outlet mill bearing temperature. Ball mill is equipped with internal liners and the balls are charged in differ ent size from the ball charge hopper. 4.2.7.2 Hot air Generator The hot air generator uses furnace oil for combustion and serves the purpose of generating hot air to dry the limestone and Anthracite coal mixture. The hot air is supplied to the mill via a hot gas duct. 4.2.7.3 Dynamic Classifier Dynamic Classifier (SEPAX) separates the fine portion of ground material from gas solid mixture of Ball mill. The fines vented from the Classifier in the ascending air stream are further subjected for separation in a cyclone, bag house, subsequently being collected as the finished product. The Coarse particles are returned back to the Ball Mil l. The Dynamic classifier is equipped with Variable Frequency Drive; the material fineness can be maintained by varying the rotor speed of Dynamic Classifier. Part of the Exhaust gases from Ball Mill ID Fan is recirculated to the system via recirculation damper to keep Gas-Solid mixture at the Ball mill outlet in suspension. 4.2.7.4 Cyclone Cyclone is a Gas-Solid separator that converts pressure energy into rotational momentum. The
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sequence of operation during start and stop. This means that no equipment can be started before the subsequent equipment has been started. Inversely, stop of any equipment will cause the stop of the preceding equipment, unless specified herein. This section outlines the division of groups; the basic terminology used in numbering of the groups, sequential Interlocks between groups and between equipment/ drives/ valves in every particular group. This section basically outlines the various process Interlocks that are to be satisfied for successful operation of a sequence. The operator has to ensure that the power source, remote selection etc., are properly ensured. In case, the same has not been ensured, the HMI would initiate the respective alarms as described in the earlier section(s)/ sub section(s). General Notes: a. Temperature, pressure, flow, level and any other process parameter set point will be adjusted and set during commissioning. Access to the set point is provided only for Engineers and not for the Operators. b. For all the analog inputs, trends are configured in the Main Automation System. c. All the electrical Interlocks for the drives and the feeders are not described in this document and shall be taken care in accordance with the general philosophy of the plant. d. Pressure switch is provided in the discharge line of all air slide fans for monitoring low pressure alarm in the Main Automation System. e. Considering the safety of the equipments, the AUTO changeover of any drives is not permitted in the mill and Dynamic classifier Lubrication system. f. During the Re-start of the plant after the power failure, the operator has to ensure that the mill drive is “ready for operation” before starting the mill discharge conveying group and Dynamic Classifier group to avoid overfilling of the material at the mill feed end and discharge end. (After starting the mill discharge group and Dynamic Classifier group, the mill drive has to be started immediately). g. After ensuring that the utilities are ready the operator initiates the starting of the plant.
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4.2.9.1 Group 1 - ID fan (P&ID: R-02-1003) 4.2.9.1.1
Group Description
The ID fan (333FN 550/B46203Q) is responsible for the primary draught and airflow through the mill system. The ID fan is located at the outlet of Bag Filter (333BF 500/B46203N) and exhausts directly to atmosphere via stack (333SK 590/B46203T). A pneumatically operated damper (333LD551/B46203QA) with louver arrangement is placed at the ID fan inlet. The damper is opened during normal operation. 4.2.9.1.2
Group 1 equipment summary
a. ID fan (333FN550/B46203Q) b. Pneumatically operated damper (333LD551/B46203QA) c. 4.2.9.1.3
Bag filter Isolation damper(333BV546/B46203U),(333BV545/B46203H) Group 1 Start Sequence
Start command of the Group initiate the following sequence: d. Close ID fan damper (333LD551/B46203QA) close limit ZAC2056 healthy. e. Start ID fan (333FN550/B46203Q) at 15% speed. f. Open ID fan damper (333LD551/B46203QA) to 10% and release it to manual mode. Normally, damper position shall be varied to maintain the draught as per requirement. g. Open Bag filter Isolation damper (333BV546/B46203U) and (333BV545/B46203H). 4.2.9.1.4
Group 1 Starting Interlocks
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- Stop ID fan (333FN550/B46203Q) - Close Pneumatically operated Damper (333LD551/B46203QA) - Close Bag filter inlet damper (333BV545/B46203H) - After a time delay (333BV546/B46203U).
(set
during
commissioning)
close
Bag
filter
outlet
damper
4.2.9.2 Group 2- Product Handling System (P&ID: R-02-1005) 4.2.9.2.1
Group 2 description
The product handling group is responsible for handling the coarse Lime-Anthracite Coal mixture from Dynamic Classifier (333SR300/B46203A).The product collected from the cyclone (333 CN400/B46203B) and bag filter 333 BF500/B46203N) is conveyed to the pneumatic transfer feed hopper (B43303). 4.2.9.2.2
Group 2 equipment summary
a. Bag Filter rotary airlock (333 RF511/B46203V) b. Bag Filter (333 BF500/B46203N) purging control panel. c.
Cyclone rotary Air lock (333 RF402/B46203C)
d. Pneumatic transfer feed hopper (B43303) 4.2.9.2.3
Group 2 Start Sequence
Start command of the Group initiate the following sequence: a.
Start Bag filter rotary airlock (333 RF511/B46203V)
b.
Start Cyclone rotary airlock (333 RF402/B46203C)
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4.2.9.3.1
5
Group 3 description (R-02-1003)
Mill ID Fan (333FN450/B46203F) is equipped with Variable Frequency drive which maintains the draught required for product classification. Part of the flue gases are routed from the fan discharge to the Mill outlet for maintaining the ground product from the mill to Dynamic Classifier (333 SR300/B46203A) in suspension. 4.2.9.3.2
Group 3 equipment summary
a. Mill ID fan (333 FN 450/B46203F) b. Pneumatically operated damper (333LD451/B46203FA) c. 4.2.9.3.3
Recirculation damper (333TV 575/B46203G) Group 3 Start Sequence
Start command of the Group initiate the following sequence: a. Open Mill ID fan damper (333LD451/B46203FA) open limit Switch ZSO2042 healthy. b. Start Mill ID fan (333FN450/B46203F) at 10% speed. c.
Mill ID fan speed shall be varied to maintain the draught as per the requirement.
d.
Open Recirculation commissioning).
4.2.9.3.4
damper
(333TV575/B46203G)
as
per
requirement
(set
during
Group 3 Starting Interlocks
Mill ID Fan group can start provided that t he following pre-requisites are satisfied a. Group 2 run feedback healthy. b. Mill ID Fan inlet damper(333LD451/B46203FA)is 100%open (open limit ZSO2042 healthy)
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h. Mill ID fan inlet vacuum PI 2038 ‘high high’ alarm is false (set at negative 701 mmwc) 4.2.9.3.6
Group 3 Stop Sequence
Stop command of the Group initiate the follow ing sequence: i.
Stop Mill ID fan (333FN450/B46203F)
j.
Close fan inlet damper (333LD451/B46203FA)
k.
Recirculation Damper (333TV575/B46203G) is 100% closed.
4.2.9.4 Group-4 Hot Gas Generator System (R-02-1004, R-08-1003) 4.2.9.4.1
Group Description
The Limestone and Anthracite coal is dried by the hot air, supplied by hot gas generator (333 HG600 / B46203I).HGG is equipped with combustion air fan (333 FN610/46203J),dilution air fan (333FN620/42203IA) with inlet dampers (333TV621(46203ZB)/333 TV611(46203ZA)) respectively along with pumping and filtration unit (w ith standby arrangement). The HGG is a single shell construction, horizontal fired system, which can produce the rated quantity of hot air on continuous basis. The system works on 100% FO fuel and has a turndown ratio of 4:1 without changing the nozzle. Apart from heat generation, this system also caters the principle quantity of airflow required in the milling system. The fuel oil is pumped from a day oil tank (of 1m3 capacity) by a set of pumps (333FP656/B410031/333FP655/B41003-2) – one operating and the other standby. The filter unit (one operating + one stand by) at the suction end (SF 201/202) and the discharge end (DF201/202) of the pumps enable a clean flow of fuel to the burner valve stand and the HGG. Each filter unit (SF201/202) and (DF201/202) is installed with a filter clog indicating differential pressure switch (DPI 3003 & DPI 3007) respectively. 0.1kg/cm2 differential pressure gauge reading ensures that there is a clog at
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c. 4.2.9.4.3
5
Fuel Oil transfer pump (333FP656/B41003-1/333FP655/B41003-2) HGG Group 4 Starting Interlock
a) Group 1 & 3 ON feedback healthy for starting combustion air fan 333.FAN610/B46203J and dilution air fan 333FAN620/B42203IA. b) Day oil tank level 333FT651/ B34032 LSL 3038 not low (set at 30%) to start the transfer oil pumps (333FP656/B41003-1) or (333.FP655/B41003-2) Hot gas generator burner start interlocks are as follows: a) Either of the oil pumps 333FP656/B41003-1 or 333FP655/B41003-2 is selected. (Only one pump can be selected at a time, by default 333FP656/B41003-1 will be selected.) b) Day oil tank level LSL3038 (set at 30%) not low to start the fuel oil 333FP656/B41003-1 or 333FP655/B41003-2. c) Temperature of oil at tank outlet TIS3036 not healthy to start tank heater (Electric heater starts at below 50 Deg.C). d) Oil pressure at valve stand ‘low’ alarm PSL3013 (set at 7kg/cm2 (g)) is not healthy. e) Atomizing air pressure at valve stand ‘low’ alarm PSL3021 (set at 7 kg/cm2 (g)) is not healthy. f)
Instrument air pressure at valve stand ‘low’ alarm PSL3036 (set at 6kg/cm2 (g)) is not healthy.
g) Main oil valve XV3016 is close (ZSC3016 healthy). h) Return oil valve XV3015 is open (ZSO3015 healthy). i) j)
Fuel Oil Control valve XV3014 is reduced to minimum firing position of 22% (ZT3013). Scavenging valve XV3022 is close (ZSC3022 healthy).
k) Combustion air fan 333FN610/ B46203J ON feedback healthy. l)
Dilution air fan 331FN620/ B42203IA ON feedback healthy.
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d) BMS PLC will monitor the combustion damper damper position and when the same remains between (25 to 30 %), “Purge Complete” lamp will stop flickering and glow steadily on Local panel. Respective message will be displayed on BMS and Main Automation System. Note: When given command of High fire or Low Fire, if respective combustion air damper position is not achieved within one minute, sequence will tr ip and Purge Sequence Fail alarm will appear on BMS and MAIN AUTOMATION SYS TEM. Operator has to start from Purge ready condition.
4.2.9.4.5
HGG burner start-up sequence
With Purge is completed and above mentioned startup condition satisfied, “Burner Ready to fire” indication lamp will be illuminated on Local Panel respective message will be displayed on BMS and Main Automation System. Now the operator could start the oil burner by pressing "BURNER START” Push button, either from Local Panel or HMI on BMS Panel or from Main Automation System (depending upon Local/BMS/MAIN AUTOMATION SYSTEM selection). If the burner start command has not been executed within 10 min of purge complete then Purge Cycle would trip and needs to be restarted. Now the operator has to execute Oil Burner start command (either from Local Panel or BMS Panel, as selected). This would initiate the f ollowing sequence: 1. Ignition Transformer will be energized energized for 15 seconds; LPG Solenoid Valve (XV3035) will also be energized to open and atomizing air shut off valve (XV3023) will be energized to open. Pilot flame will be established and "PILOT ON" & "IGNITION ON" indications will be illuminated on both Local as well as BMS Panel. 2. If flame will not not be sensed sensed by flame flame scanner (FS 901) within ignition period, then after ignition ignition period with ignition transformer, pilot valve (XV3035) and atomising air shutoff valve (XV3023) will be de-energized and "FLAME FAILURE" annunciation will glow on BMS panel. Operator has to re-start the system from “PURGE READY” Cycle. 3. With Flame Sense by the scanner scanner (FS901) during during ignition period, "FLAME "FLAME ON” indication will be illuminated on BMS panel & Local Panel.
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4.2.9.4.6
5
HGG Group 4 Running Interlock
a) Group 1 & 3 ON feedback healthy for running combustion air air fan 333.FN610 and and Dilution air fan 333.FN620. b) Day oil tank level 333FT651/B34032 333FT651/B34032 LSL3038 not low low (set at 20%) to start the transfer transfer oil pumps 333.FP656/B41003-1 or 333FP655/B41003-2 burner run interlocks are as follows: c) Hot gas generator burner 1. Day oil tank level level LSL 3038 not low (Set at 20%) to start the the fuel oil 333FP656/B41003-1 333FP656/B41003-1 or 333FP655/B41003-2. 2. Temperature of oil at tank outlet TIS 3036 3036 NOT healthy to to start tank heater heater (Electric heater 0 0 starts at below 50 C Stops above 60 C). 3. Oil pressure at valve stand ‘low low’ alarm PSL3013 PSL3013 (set at 7kg/cm2 (g)) is not healthy. 4. Oil pressures at valve stand stand ‘high high’ alarm PSL3018 PSL3018 (set during commissioning) commissioning) is not healthy. 5. Atomizing air pressure at valve valve stand ‘low’ alarm PSL3021 (set at 7 kg/cm2 (g)) is not not healthy. 6. Instrument air pressure at valve stand ‘low’ alarm alarm PSL3036 (set at 6kg/cm2 (g)) is not healthy. 7. Main oil valve XV3016 is open (ZSO3016 healthy). healthy). 8. Return oil valve XV3015 is close (ZSC3015 healthy). 9. Combustion air fan 333FN610 ON feedback feedback healthy. 10. Dilution air fan 331FN620 ON feedback healthy. 11. No flame inside the furnace (FS 901) 12. Emergency press button not pressed 13. HGG Refractory temperature TIC 3033 ‘high high’ alarm is false fal se (set during commissioning) 4.2.9.4.7
Oil Gun Scavenging Cycle
Whenever the Oil Burner trips or withdrawn from service by pressing the "BURNER STOP” Push button, oil gun scavenging cycle for the burner will be initiated so that the oil line after Shut off
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a. Emergency stop not pressed b. Flame healthy (FS901) c.
LPG Pressure not Low (PSL3025 not healthy)
d. Instrument Air Pressure not Low Low (PSL3036 not healthy) e. Combustion Air Fan (333FN610) Running f.
Atomizing Air Pressure not Low (PSL3021 not healthy)
If scavenging cycle trip / not started due to any of above mentioned condition then the oil collected at the downstream of the shut off valve shall be manually drained by the operator to keep the oil line down-stream of shut off valve clean. After completion of scavenging cycle and with all startup interlocks healthy, operator can restart the system from ready to purge cycle. 4.2.9.5 Groups 5 – Dynamic Classifier main drive, Grease spray system and Air slide system description (P&ID: R-02-1003) 4.2.9.5.1
Group Description
The purpose of Dynamic Classifier (333SR 300/ B46203A) is to separate the grounded dust particles in to fines and coarse. The coarse particles are fed back to the mill for further grinding via single gravity flap valve (333 FV306/B46203K), air slide (333AS370/B6203L) and double gravity flap valve (333FV065/B46203Z). The fine particles are carried to product Cyclone (333 CN400/B46203B) where it is collected as a product. Dynamic Classifier is equipped with Variable Frequency Drive, Speed shall be varied for the desired the fines to be achieved in the product size. Solid flow meter (333FM380) located at the discharge of Airslide (333 AS370/B46203L) to measure the mass of the material recycle to the mil l.
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c. 4.2.9.5.3
5
Grease spray system (333GS 305). Group 5 Start sequence
Start command of the Group initiate the following sequence: a. Group 4 run feedback to be healthy b. Start air slide fan (333FN 371/B46203M) c.
Start Dynamic Classifier motor (333MD302) at a minimum speed as per the requirement.
d. Start the grease spray system (333GS305). 4.2.9.5.4
Group 5 Starting Interlock
Conditions to be fulfilled before starting Group 5A Dynamic Classifier drive a. Grease spray system (333GS305) fault alarm is not present. b. Dynamic Classifier shaft temperature TI2028 ‘high’ alarm not activated c. 4.2.9.5.5
Shaft bearing Temperature TI2082 ‘high’ alarm is not true. Group 5 Running Interlock
Conditions to be fulfilled in order to run the Group 5B is as f ollow a. Dynamic Classifier shaft temperature TI2028 ‘high high’ alarm not activated b. Grease spray system run feedback is healthy .The separator drive trips after a time delay of 1200 seconds elapses and the grease spray control panel fault indication persist. c.
Shaft bearing Temperature TI 2082 ‘high high’ alarm is not true.
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Capacity of the sump tank is 250 litres. Tank utilizes 2 drain lines from bearing ("dirty hot oil") housing for oil return to the tank by gravity. This passes through a basket strainer which is accessible through a hinged inspection door for easy cleaning. Each return line is fitted with an oil flow sight glass. The correct oil temperature in the sump tank is maintained by 3 kW heater elements, monitored by a Temperature transmitter (TT6008). The heater operates between oil temperatures of 32-38. From a cold start-up, the 3kW heater will raise the oil temperature from 15–38 within 2-3 hrs. An oil level transmitter (LT6007) is Interlocked for oil level monitoring. If oil level drops below the 15% of tank height, all auxiliary equipment must be tripped (pump motors & heater). An alarm is raised if the oil level drops below 25% of tank height. The oil level sight glass fitted to the tank gives visual indication of oil level & temperature. Air breather / filter allow clean air to enter the tank. Drain valve plug is available to drain the tank, when required. Access to the tank internals is gained by removing the tank lid, which is bolted down. Conditioning & LP Circuit The sump tank is fitted with 2 LP oil gear pumps (One Working & One Standby) integral pressure relief valves (PSV6003 & PSV6034) (set @ 20 bar), driven by a 3 kW TEFC electric motor. The pump suction is isolated from the tank via a ball valve; discharge end is isolated via a non return and ball valve. The oil flow rate in the LP circuit is 47 lpm, which is monitored by pressure gauges, flow transmitter (FIT6032), temperature gauges and oil temperature transmitter (TT6012) exiting the cooler. If the oil flow falls below 36 lpm, an alarm is raised. Oil exiting the cooler should be maintained @ o 0 50 C, and an alarm is raised if it is higher than 59 C. The “dirty & hot oil" from the sump tank is pumped to a high capacity LP duplex filter and thereafter, to a Plate Heat Exchanger (PHE). The duplex filter unit is fitted with filter clogged visual indication and electrical differential pressure transmitter (DPI6025), which indicates the operator to "change-over' of the clean unit on-line, thereafter, to replace the clogged filter element with a new / cleaned element, bleeding the filter bowl & equalizing the f ilter pressure.
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& 35 bar with mill running pressures are inter-locked with the PLC and trips the mill if it is incorrect. The HP pump shall be started 10 minutes prior to Mill Main drive and stops 10 minutes after complete stop of the Mill Main dri ve, to allow for accurate hydrodynamic pressure monitoring. Above values given are estimates, and should be fine tuned on commissioning 4.2.9.6.2
Group 6A equipment summary
a. Settling compartment heater HE1. b. Operation and Control Philosophy for Additive Dry Grinding System c. High pressure pumps motor or by default start pump motor selection to be made available in MAIN AUTOMATION SYSTEM. d. Low pressure pumps motor or by default start pump motor selection to be made available in MAIN AUTOMATION SYSTEM. 4.2.9.6.3
Group 6A Start sequence
Start command of the Group 6A initiate the following sequence a. Start heater HE1 b. Start the selected HP pump motor 10 minutes before startup of the mill and stop after few minutes (set during commissioning) when the mill is ru nning. c. 4.2.9.6.4
Start the selected LP pump motor Group 6A Starting Interlock
This group can start provided that the following conditions are satisfied a. Sump tank low level LT6007 (Set at 25%) alarm is false for starting motor. o
b. Sump tank temperature low alarm TT6008 (set at <32 C) is false to put heater ON and
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f. 4.2.9.6.6
5
0
Oil temperature at cooler exit TT6012 (>59 C) high high alarm is not true. Group 6A Stop sequence
Stop command of the Group initiate the follow ing sequence a. Stop heater HE1 b. Stop the HP pump motor 10minutes after the mill stops.
c. 4.2.9.6.7
Stop the LP pump motor Main Gearbox Lubrication system
The ball mill main gear reducer is lubricated utilizing water cooling system with 8lpm of water for cooling the Gear Box system. 4.2.9.6.8
Group 6B –Mill Main Drive and grease spray lubrication system (P&ID: R-02-1007)
Group 6B Description: Ball Mill drive Lime stone and Anthracite Coal mixture size reduction takes place in ball mill (333BM 100/B46203). The off gases with materials are directed to Dynamic Classifier (333SR 300/B46203A). The heavy materials recycled from Dynamic Classifier to the ball mill via sluice flap (333FV 306/B46203K), Air slide (333AS 370/B46203L) and sluice flap (333FV 065/B46203Z). The operator has to ensure that the Mill is not operated without feed material. Ball Mill Inching Mode It is to be noted that inching drive engage or disengage status has also to be monitored locally. A proximity Switch (ZSC2018) is provided in the jaw clutch coupling to ensure the disengage before the start-up of the mill main motor.
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e. The grease strainer is blocked The air pressure switch PSL6038 will fail to signal the PLC if the 2/2 way solenoid valve is faulty, or if the plant air pressure is low or off line. The pressure gauge gives visual indication of the system air & grease pressure. The pump should trip if no pulses are generated from the distributors, or the air pressure switches are not a ctivated. The mill should then also trip. 4.2.9.6.9
Group 6B equipment summary
a. Ball mill main drive (333MD 140) b. Grease spray system (333 GS137) 4.2.9.6.10
Group 6B start sequence:
a. Start Main bearing lubrication system (333LQ110) b. Start mill main drive(s) (333MD140). It is started after 600 seconds of main lubrication system operation (HP pump) and 300 seconds of water cooling system. Stop the HP pump after 10 minutes, start HP p ump when the stop command is initiated for the main drive c. 4.2.9.6.11
Start the grease spray system (333 GS137) Group 6B starting Interlock
This group can start provided that the following conditions are satisfied a. ID fan (333FN 550/B46203Q) running feedback healthy. b. Group 5 running feedback healthy. c.
Mill ID fan (333FN 450/B46203F) running feedback healthy
d. Mill outlet gas temperature TI2030 ‘high’ alarm is false (Set at 110)
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b. Group 5 running feedback healthy c.
Mill ID fan (333FN 371/B46203L) running feedback healthy
d. Dynamic Classifier (333 SR300/B46203A) Running feedback to be healthy e. Air slide (333AS 370) fan (333FN 371) running feedback healthy f.
Ball mill feed end bearing temperature TI2012 “high-high” alarm is false (set at, 65 )
g. Ball mill discharge end bearing temperature TI2020 “high-high” alarm is false (set at, 65 ) h. Ball mill pinion temperature TI2019 “high-high” alarm is false (set at, 75 ) i.
Mill motor bearing temperature TI2015 “high-high” alarm is false (set at, 80 )
j.
Mill motor winding temperature TI2013 “high-high” alarm is false (set at, 120 )
k.
Mill motor vibration VI2014 “high high” alarm is false
l.
Mill bearing lubrication system (333 LQ110) - Group 6B system running feedback healthy
n. Grease spray system (333 GS137) run feedback is healthy The drive trips after a time delay of 1200 seconds elapses and the grease spray control panel fault indication persist 4.2.9.6.13
Group 6B Stop sequence
Stop command of the Group initiate the follow ing sequence: a. Start HP pump b. After 10minutes stop mill motor (333 BM100/B46203) c.
Stop Grease spray pump (333GS137)
d. After 10minutes stop HP pump NOTE: Group 6 Interlocks are also applicable when the mill is run using Inching Drive.
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The initial 90% closing and delay in closing final 10% will be done by mounting two pneumatic cylinders back to back. First air cylinder is activated on receiving signal and it will close damper 90%, then second air cylinder after receiving signal will close damper remaining 10 % to seal it tight. The damper shall also be complete with fail-safe design which shall close damper upon loss of air and electric control signal and provide low air pressure alarm signal. For inlet damper (333.BV545/B46203H), proximity switches shall b e provided for indication of open ZSO2072 and closed ZSC2072 positions. For outlet damper (333.BV546/B46203U), proximity switches shall be provided for indication of open ZSO2080, 90% closed ZSC2080 (90%) and closed positions ZSC2080. 4.2.9.7.1
Emergency Power
Emergency power availability is envisaged for the following drives. •
Mill main bearing lubrication system (333 LQ110)
•
Mill Cooling water control system
The above drives should continue to run / start immediately when there is a power failure. The operator can decide and stop the system based on the requirement. HGG-Closed Control Loop: Dilution Air Damper Control: a. Dilution Air Damper actuator will be operated with respect to the HGG outlet temp. Increase in HGG outlet temperature will increase the damper opening (towards open position) and decrease in HGG outlet temperature will decrease the damper opening (towards close position). b. The outlet temperature of the HGG will be sensed by Thermocouple (TC3033) and converted in 4-20mA by Temp. Transmitter (TT3033) provided at the HGG outlet & the signal will be fed into BMS PLC as input to control loop. The control loop needs to be configured in the BMS PLC
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decreasing demand. (Lead-lag control between fuel oil and combustion air) PHF UNIT LOGIC a. Before starting the process, operator has to start Oil pump 1 or 2 (as per selection from Main Automation System). b. Before starting any of the pumps, Main Automation System will check day Oil tank level not low. If the same is unhealthy operator has to first fill-up the tank up to sufficient level. If the pump is not able to deliver sufficient pressure at Pump outlet (PG3004) then operator should start the second pump and stop the first one. c.
Along with the pump, operator has to start line heater-1 or 2 (depending on the selection from Main Automation System). Line Heater is used to keep PHF unit outlet oil temperature at 120°C. This is achieved with the help of Temperature indicating switch mounted at the outlet of each heater (TIS 3006 and TIS 3005 respectively). There are two set-points (First Set-point at 118°C and Second Set-point at 120°C) in each TIS. These set-points are taken as an interlock in MCC Panel (by client) for controlling ON-OFF operation of each bank of Line Heaters. Line heaters (1 and 2) are consisting of two banks each (Bank-1 of 9 kW and Bank-2 of 6 kW).
d. Along with Temperature indicating switch, both Line Heaters are also provided with 1 no. Thermostat, which will be used to trip electrical heater in case the temperature inside electrical heater rises above 130°C. This is used for protection of Electrical heater. This needs to be terminated to MCC Panel in electrical heater trip circuit. 4.2.10 Control Philosophy 4.2.10.1
Introduction
The system operation is evaluated on a continuous basis with the help of the various instruments in the system. The major control parameters and controlling Variables are vital for smooth operation of the system. This section details on the various control parameters and controlling Variables. This section also describes various abnormal control operations that would be required from time to time as the system may demand and that could either be programmed or the operator can
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to achieve this set point. 4.2.10.5
PID controller unit structure
A standard PID controller will have the following requirements: 1. Mode of selection 2. Failsafe operation 3. Alarm generation and masking 4. Bad PV handling 4.2.10.6
Mode selection
All PID controller units will have the following modes of operations: 1. Auto - the controller output is calculated such that the PV matches the set point; 2. Manual - the controller output is directly set by the CRO. 4.2.10.7 Fail safe mode In the event that the PV drifts out of range to an unsafe Value, the controller unit will divert to manual mode and a failsafe output. The PV must be corrected and the controller unit placed in auto before the output will again function in a uto control. 4.2.10.8
Alarm generation and masking
In addition to alarms generated for the Bad PV, alarms will also be generated for excessive deviation from the set point. The deviation alarms will include dead band levels to prevent spurious operation. Any masking requirements for controller units will be more complex than for analogue devices because the masking is based on process conditions. PV alarm masking may be implemented for each individual limit, based on different process conditions. The alarm masking is defined in the PID Controller Functional Descriptions.
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4.2.10.13
5
Feed Control
The desired set value of feed is given in the MAIN AUTOMATION SYSTEM. The in built PID controller in the Limestone & Anthracite Coal weigh-feeder (JSPL Scope) panel varies the belt speed to achieve the desired target value. This mode of operation also called gravimetric mode, is the desired mode of feed control by the weigh-feeder. This mode of operation can independently maintain the mass flow rate irrespective of changes in feed granulometry, bulk density or moisture. The weigh-feeder can also enable to operate in the volumetric mode in which the belt speed will be fixed as set point. This is a direct control on the weigh-feeder belt and does not respond to the physical changes (like granulometry, bulk density etc.) in the raw material. Volumetric mode operation is possible only from the feeder panel. This PID loop is generally a part of the complete system in the weigh-feeder locally situated control panel and might not require any programming in the centralized control system unless specified. However, the centralized control system will have provisions to give material flow (in TPH wet) set point. 4.2.10.14
Differential pressure drop across the bag filter
The pressure difference across the bag filter DPI2053 initiates and stops the bag cleaning system. It is also a real indication on the status of the system in terms of airflow and fineness apart from the condition of the bag filter. 4.2.10.15
Operation Sequences
4.2.10.16 Integrated Start Sequence The integrated start sequence is given as a guideline for starting the plant. Automatic start sequence is not recommended. a. Start ID Fan – Group 1 b. Start Product Classification & Handling System – Group 2. c.
Start Mill ID Fan– Group 3.
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4.3
5
Pneumatic Conveying System for Grounded Coal/Limestone (R-02-1005) (Inputs received from package vendor Macawber) A pneumatic conveying system is installed for Coal/Limestone transfer in the Additive Grinding Building. The MACAWBER Model 75/12 “Denseveyor” is a low velocity, dense phase pneumatic conveying system that consists of a Pneumatic transfer feed Hopper (B43303), a Transport Vessel with a dome valve, terminal box, automatic controls and a local control panel. The relatively low velocities employed minimize conveying air consumption, conveying pipe wear and the size of dust collection system on the receiving end. The expected capacities of flow for the two additi ves are as follows: Additive (TPH)
Average Flow
Design Flow
Limestone
20.9
40.0
Coal
19.1
40.0
The Pneumatic Transfer System receives solid material from the Additive Grinding Mill and must be activated during the Mill start-up procedure. Dry, fine additives flow to the Pneumatic System Feed Hopper from the Grinding S ystem Cyclone and Dust Collector. The Feed Hopper is equipped with high and low level switches. When the Feed Hopper is full, the high level switch signals the central system to open the vent valve on the Transport Vessel and position the dome valve in the fill position. Material then flows from the Feed Hopper into the Transport Vessel until it is full. This dome valve is a patented MACAWBER design which reliably closes and seals through either a static or dynamic column of material. When the filling cycle is complete, the dome valve closes and the Transport Vessel is pressurized with dry compressed air at a controlled rate. The conveying gas is introduced at the top and bottom of the Transport Vessel and transfers the material to the appropriate Additive Storage Bin.
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(d) If the above condition is satisfied along with sufficient level of feed hopper for conveying and Bypass timer not on, a check is made for discharge silo level (is not high) and diff pressure across venting arrangement is normal (50-70mmWG). If level is high and if diff pressure is high, alarms are generated. (e) If discharge silo level is low and venting diff pressure is ok as mentioned above, material inlet dome valve and vent dome valve SOVs are energized. (f) After the valves are energized, a check is made for seal confirmation through the pressure switches for inlet dome and vent valves. If there is not sufficient pressure, an alarm is generated. (g) If there is sufficient pressure, then solenoid valve is energized which will start the material conveying. (h) When the material conveying starts, a timer for minimum blow for duration of 15 sec and a timer for pipe blocked for duration of 75 sec starts. (i) After both timers duration is over, a check for low pressure is made via the pressure transmitter. If pressure is high, an alarm is generated for pipe blocked and the system is taken into manual operation. (j) If the pressure is low, then convey on SOV is de-energized and seal delay timer for inlet and vent dome valve starts. (k) When the seal delay timer is over, seal SOV for Inlet dome and vent valve is de-energized and the timer is again restarted for another round of conveying operation. Coal and Lime stone Storage Bin (B43501) is equipped with two load cells and a weight indicator (WI) which produces an indirect measurement of the solids level in the bin. If the bin level reaches total capacity, the WI sounds an alarm and shuts down the Pneumatic Conveying System. High, High level from both Pneumatic transfer feed Hopper and Coal and Lime stone Storage Bin will stop the additive grinding system. 5.0
MIXING –AREA 3 (Hold. Inputs Awaited From Eirich)
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Main Automation system totalizes the flow rate with time and displays both instantaneous weight flow rate and totalized flow. 5.3
Ground Bentonite Storage Bin -- Discharge Rate Control (P&ID: R-03-1003) Discharge from Bentonite storage bin (B43504) is controlled by a loss in weight feeder (B55003) fitted with a geared motor. The actual weight flow rate is controlled by the weight indicating controller (Loop No: WIC - 3311). Provision for both automatic and manual control is envisaged from the main automation system logic controller WIC-0400. The controller compares the actual weight flow rate to the set point and adjusts the geared motor on the LIW feeder to achieve the required flow rate. The set point is the desired flow rate manually input through the DCS. The DCS totalizes the flow rate with time and displays both instantaneous weight flow rate and totali zed flow.
5.4
Ore And Additives -- Proportion Control Required feed rates can be calculated off line and entered manually as set points at the Main Automation system for each controller to achieve the desired total feed rate and proportioning on a dry basis. The Main Automation system can also automatically calculate the required feed rates as remote set points to the controllers. The Main Automation system controls the feed rates of iron ore filter cake (10% H2O), coal + limestone and bentonite to achieve a total desired feed rate of these components in their desired proportions. The Main Automation system interface permits the operator to enter the desired total feed rate, component fractions for bentonite and coal + limestone. The ore fraction equals one minus the sum of the bentonite and coal + limestone fractions.
5.5
General Three separate controllers are required in the mixing control system • • •
WIC-3111/3121 WIC-3211 WIC-3311
Iron Ore Filter Cake Feed Rate to the Mixer, TPH Coal / Limestone feed rate to mixer, TPH Bentonite feed rate to mixer, TPH
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belt conveyors (B43087-1,-2) with weigh scales (WIC-03B3111 and WIC-03B3112) and Rotary Weigh Feeder (B55005). Additives, Coal/Limestone, Bentonite, and Organic Binder are metered by loss-in-weight feeders (B55001, B55003, and B55004) onto the Mixer Feed Conveyor MF-11 (B43026), which will discharge into a vertical mixer (B45110). Individual start-up of blended ore conveyors FCF-11& 12 and mixer feed conveyor MF-11 will depend on healthy signal from the safety switches placed on the conveyors. 5.6.2
Mixer Function (Preliminary description furnished. Details awaited from Mixer vendor Eirich) Mixing pan rotates with eccentrically positioned rotating mixing rotors and fixed multi-purpose tool as flow deflector. The multi-purpose tool divides and deviates the material stream. Split material streams are created and produce a macromixing effect. The rotor acts upon the circulating material stream which is caused by mixing pan and flow deflector and produces a micromixing effect.
5.6.3
Mixed Material Handling The Green Fines Return conveyor (GFR-11B) (B43042) deposits fines returns along with mixer discharge to the Mixed Ore Conveyor MO-12 (B43026). The MO-11 (B43027) conveyor transfers material to MO-12 (B43026) and MO-13 (B43032), and MO-14. At this point, the appropriate belt plow will dump mixed material to Balling Disc Feed Bins (B16215-1, 2, 3, 4, 5 & 6) or directly to Balling Disc Feed Bin 7 (B16215-7). MO-13 wi ll discharge into mixed ore conveyor MO-14. Individual start-up of mixed ore conveyors MO-11, 12, 13 & 14 and green fines return conveyor GFR-11B will depend on healthy signal from the safety switches placed on each conveyor. Mixer will start / stop once MO-11 starts / stops. Group start in a sequential manner (MO-14 MO-13 MO-12 MO-11) will depend on the lower level signal of the Balling disc f eed bins and / or healthy signal from conveyor safety switches.
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“seed pellets”, which comprise the nucleus of the pellet. Further rolling in the disc causes the “seeds” to grow. Within the disc charge, the balls segregate into flow paths according to size and density, the smaller and less dense particles being carried, by the rotation, closer to the top of the disc before falling back under their own weight. As the “seeds” become larger they gradually migrate from the disc bottom to the charge surface achieving the desired product size range. At this time they reach the lip of the disc sidewall and overflow to the green pellet- collecting conveyor. This is a continuous operation as long as balling feed is continually introduced to the disc. The rate of growth of the green balls can be controlled by the disc speed and the addition of spray water as necessary. However, too much spray water addition will result in the production of oversize and wet plastic balls which will tend to deform on their passage to the furnace. Too little moisture in the balling mix will restrict the formation of seeds and result in a build-up of unagglomerated material in the disc and a dry, friable, undersize product. The correct disc axis angle must be established during startup. This angle combined with the disc speed establishes the most beneficial balling path for the material. The discs will be initially set at 47 degrees. In summary, the operator controlled parameters which govern the balling operation are primarily feed moisture, disc speed, feed rate, and water spray location. Additional parameters usually determined at startup are disc angle, the point at which feed is introduced to the disc, and plow location and angle. Ore size structure, Blaine particle surface area, and level of binder additive are also important factors for quality balling feed. The seven (7) balling discs discharge onto seven (7) green pellet conveyors GP-11A through GP11G which in turn discharge the pellets to collecting conveyor GP-12. Conveyor GP-12 transports the green pellets to the indurating area. There, the pellets are transferred to wide belt conveyor GP-14 which then deposits the pellets onto the upper roller conveyor (B43037E). The function of the upper roller conveyor is to screen out oversize balls. The lower roller conveyor screens undersize green balls before finally depositing product size green balls onto the grate for induration. The oversize green pellets screened at the upper roller conveyor are passed through a shredder
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6.1.2.2 Balling Disc Feed There are seven balling circuits, each consisting of a balling feed bin; a variable speed disc feed conveyor, BDF-11A to G, with a belt scale, a balling disc and a disc discharge conveyor, GP-11A to G. Mixed ore is withdrawn from each bin by the variable speed conveyor controlled by a weight indicating controller in conjunction with the belt weigh scale (Loop No: WIC0106/4101/0203/0223/0303/0323/0403). The controlling parameters of balling discs are disc feed rate as indicated above, manually adjusted disc spray water addition and manually adjusted disc rotational speed (rpm). Spray water addition is automatically stopped when the balling disc stops. Each disc is equipped with field rotational speed indication, spray water flow indication, and disc position tilt angle. 6.1.2.3 Start-Up There are three cases to consider: -
Initial disc start-up
-
Starting a disc under full load
-
Starting a disc that has been “cleaned out” (operated for several minutes without feed prior to shutdown).
A new disc must have its mesh lining filled in with mixed ore (bedded). A mixed ore material with elevated bentonite (2-3%) and moisture (10-12%) contents should be used for this “bedding” procedure. The disc should be operated at low speed (<4rpm) and feed rate (<50tph) during this
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a) Green pellet conveyor, GP-11A thru G (B43031-1 thru 7) will start first provided Green pellet collecting conveyor GP-12 (B43034) running and healthy signal from conveyor safety switches. b) Balling disc (B46005-1 thru 7) will start up on receiving running signal from Green pellet conveyor. c)
Once balling disk starts high pressure water solenoid valves will be open.
d) Balling disc feed conveyor, BDF-11A thru G will start once balling disc starts and healthy signal from conveyor safety switches. In order to process different ore types, balling disc speed, scraper position, water sprays, disc angle, and feed point will be adjustable. Normally, only minor adjustments to water addition and disc speed will be needed to produce good quality green pellets. Following the initial setup for the disc, the other adjustments will be necessary only when there is a significant change in the ore characteristics. Speed is adjusted by field operator. Other adjustments are manual. 6.1.2.4 Normal Operations The balling disc is used to form pre-wetted ore into nominal 1/2" diameter balls called "green balls" or "green pellets". The strength of the green pellet is determined by the natural surface tension of water and other adhesive forces, causing capillary action of the water in the spaces between the small particles of ore. The finer the material, the more t he adhesive forces are capable of forming strong agglomerates. A controlled amount of pre-wetted ore is fed to the balling disc. The rolling action on the disc initially forms seed pellets which grow larger by picking up additional particles of new feed as they roll across the disc. Based upon controlled disc parameters, the pellet then discharges at the desired diameter or product size over the lip of th e disc.
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A good operator will learn how the three streams look under normal operation, and take corrective action when a change becomes apparent in the third or second stream. If corrective action is delayed until an upset is apparent in the product, stable operation will be difficult to achieve. When the disc is operating in a continuous or steady state condition, the on size discharge rate will equal the new feed material rate to t he disc. The discharge size analysis will remain very stable as long as the moisture content of the feed material does not vary. If the moisture content of the feed material to the disc is not controlled, the disc will operate in an inconsistent manner. If the feed material moisture increases slightly, the pellets on the disc will increase in size. This takes a little time but the product being discharged will be larger. To correct this: -
If water is being added on the disc, reduce the amount of water addition. This should be done in steps, rather than cutting all of the water. Wait for the change to take effect. This can take from ten to twenty minutes to see the results.
-
If no water is being added, increase the feed rate slightly. A rule of thumb is to not add more than 10% of the feed rate at one ti me.
If the feed material moisture increases quite a bit, + 0.5% or more, the pellets on the disc will increase in size very rapidly. Usually the on-size pellets will travel to the second and at times the third stream. When this happens the larger pellets pick up the seeds and any fines available on the disc. The disc fills with over-size product, the discharge rate is reduced, the seed formation and intermediate size pellet growth is eliminated. Unless immediate steps are taken, this condition will continue. To improve this condition:
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If the pellets are still too large the operator has one option left. He can change the disc angle. This change should be done in one degree increments, for example change from 47 to 48. When operator changes the angle, he usually has to make slight adjustments to the r.p.m to balance the disc operation. If the operator increases the angle, he needs to increase the RPM slightly. (Return to original setting when material returns to n ormal). When the feed material is very wet it is not a good idea to increase the feed rate. The disc carries a heavy load of material and classification is very poor. If the feed material moisture decreases slightly, the pellets on the disc will decrease in size. This change also takes time. Operator will have time to make changes without upsetting the disc operation. To correct this condition, take a reading on the flow meter, then increase the amount of water addition on the disc. This should be the only change needed. Allow sufficient time to see the results (Return to normal setting when material returns to normal). If the feed to the disc quickly becomes very dry, if water is not immediately increased, the on size product will discharge very quickly and the disc will be filled with seeds. With a disc full of seeds it can take up to 30 minutes to sufficiently wet the seeds to force pellet growth. In some cases it may also be necessary to reduce the disc feed rate to compensate for the feed moisture loss. When bringing the disc back from a dry condition, it is very important to reduce the high volume of spray water at the correct time or the pellets could grow very quickly due to their wet state. If the pellets grow larger than desired, reduce the spray water in steps rather than all at once. The disc could again go dry, discharging the growing pellets and leaving only a disc full of seeds again. Controlling the disc water sprays is really a balancing operation which requires observation and a lot of patience by the disc operator. Knowledge of disc feed material and the proper water addition with the sprays can only be gained by experimenting and observing the reaction of the total disc and the final results. 6.1.2.5 Summary
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Shutdown As is obvious from the earlier start-up procedures a disc can be shut down either fully loaded or with a reduced load. This will be driven by operator preference or whether the shut down was unplanned. In any case, whenever the feed to a disc is stopped, the spray water addition must be stopped. If the disc is stopped, design is for this to occur automatically. However, due to t he severe problems that can result, spray water shut-off should be checked locally in the field.
6.1.2
Balling Disc Grease Lubrication System (P&ID: R-04-1005, R-04-1006) Compressed Air and grease are directed to each disc via the Gear Lubrication Systems (B46005A1, 2). Compressed air is used to provide the grease to disc drives. The system supplies lubrication to 7 nos of Palletizing Disc Units. All the 7 lubrication units are fed by a common Pumping station but each system has its own, separate functional components for independent working. The operation is automatic. The 7 disc lubrication units are normally operated simultaneously. A provision has been made for selective operation so that lubrication on one or more discs, if so desired, can be suspended temporarily, for maintenance etc. Though the units operate simultaneously, each unit has its own separate initiation signal. Hence the 7 cycles may or may not run synchronously depending upon the start signal for each. Each disc lubrication unit can be run in local or r emote mode. Description of Automatic Operation: The automatic operation can be initiated locally or from remote by means of a selector switch. The operation in both modes is identical except for the initiation signal. In the local mode, the operation starts through Local mode selector switch. In the remote mode, the operation starts through a signal from the VFD for the corresponding pelletizing disc through the main automation system. As soon as the system gets a start signal, the pneumatic solenoid valve for the grease pump energizes and the pump starts delivering grease to the system.
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During the operations, system fault is generated under following conditions: 1. 2. 3. 4. 5. 6.
The compressed air pressure falls below set point. The grease level at the pump station becomes low. The grease pressure at the distributor drops below the set point. The distributor cycle is not completed within a preset time period after the start signal. The spray air pressure at the nozzles drops below the set point. The ball valve on the grease line of the corresponding grease line is not open.
The system fault is annunciated by a hooter. The system stops functioning. The system stoppage is either for all the Discs or only for the faulty unit depending upon the nature of the fault. The system can be restarted after the faulty condition is rectifi ed. 7.0
INDURATING - AREA 5
Green pellets from the balling discs will drop onto green pellet conveyors GP-11A thru GP-11B which in turn feed onto green pellet conveyor GP-12 (B43034). GP-12 conveyor has a reciprocating head (B43034A) dumping onto the Wide Belt Conveyor (B43036). Pellets are distributed across a wide belt conveyor (B43036) by a reciprocating Head pulley mechanism. The pellets are screened and conveyed to the pellet induration machine by a double deck roller screen (DDRS). The off-size pellets are screened by the DDRS ahead of the indurating machine and recycled back to the balling circuit. Oversize pellets travel through Green Oversize Return Conveyor (B43037A) to the Oversize Pellet Shredder (B43037D) onto Green Fines Return Fines Conveyors GFR-11A, B, (B43037C, B43042) to MO-12 (B43026). The green pellet conveyors and DDRS reject conveyors are sized for a rejection rate of 40 percent, although recycle rates of 25% or less are anticipated. 7.1
Green feed to machine starting sequence 1) On receiving group start command from HMI lower roller conveyor (B43037F) will start first depending on healthy signal from c onveyor safety switches.
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obtain thermal efficiency. Only relatively cool, moisture laden gases are discharged to process gas cleaning and then to the atmosphere. During normal operation, the 75 mm to 100 mm thick bed of hearth layer will perform three important functions. A. It will create a temperature gradient between the bottom of the new bed and the metal grate components, so that the grate components are exposed to gases cooler than the roughly 1300 C at the bottom of the new bed. B. The high level heat, which is stored in the hearth layer, is efficiently returned to the process during updraft cooling. C. It will diffuse the gas flow passing through the relatively small fraction of open grate area, thus ensuring uniform gas flow through the new bed. The hearth layer thickness is adjustable by the operator to a maximum height of 300mm. This feature will also permit “idling” the machine by re-circulating full depth hearth layer, while maintaining the gas temperatures in all zones, and to gradually increase the green pellet feed rate from zero without producing any off-specification product. During interruptions in green pellet feed, the hearth layer gate is raised to cover the grate and to maintain grate speed. Side layer chutes (B400011) are used to protect side plates from high temperatures and to maintain pellet quality. Pellet induration will occur on the 4.0 m wide traveling grate. The anticipated total bed height of hearth layer plus green pellets will be constant up to approximately 500 mm. The speed of the traveling grate is variable and automatically controlled to maintain a constant bed height. The indurating machine (B40001) will have five furnace processing zones, updraft drying, downdraft drying, preheating, firing and cooling. In the updraft drying zone, gas flow will remove free water from the lower portion of the pellet bed while heating that layer to a temperature at which condensation will not form when the gas flow reverses in downdraft drying. The updraft
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The gas flow scheme is designed to recuperate a significant amount of sensible heat from the process gas streams. High level heat is recuperated directly from the first cooling zone, while low level heat is recuperated from the second cooling zone for drying at temperatures, which avoid the use of exotic materials of construction for the updraft drying fan. Process parameters may be reset to optimize the induration pattern as campaigns of different t ypes of pellets are run. Additional heat for indurating is supplied by burners firing either fuel oil or fuel gas. Oil heaters, pipe insulation, and electric heat tracing of oil lines are incorporated into the plant design. 7.3
Hearth Layer Bin Load cells sense the weight of fired pellets in the hearth layer bin (B54013). A level transmitter (LT-05B0206) sends the signal to the DCS which compares the signal with the bin level set point and accordingly regulates the variable speed drive on HL-12 conveyor (B43071). Hearth layer bin level is maintained at approximately 85% full. Abnormal bin level alarms are provided on the HMI for high level (95% full) and low level (50% full). Hearth layer bin set-point is entered via the HMI.
7.4
Indurating Details
7.4.1
Indurating Machine Pellet Bed Depth (Primary System) The primary pellet bed depth control system uses three (3) ultrasonic level probes to monitor total bed depth and one (1) ultrasonic level probe to monitor the hearth layer bed depth. The difference between the average total bed depth and the hearth layer depth equals the green bed depth. Total bed depth is controlled by means of machine speed modulation via the bed depth controller on the HMI. Hearth layer depth is fixed by setting the position of the hearth layer gate. All three (3) signals, total bed depth, green bed depth and hearth layer bed depth are displayed on the HMI. A DCS selector switch is used to choose the active level instrument: Average, East, Center, or West. The hearth layer is measured by the hearth layer transmitter (LIT-05B0210 A t hru D) Indurating Machine Pellet Bed Depth (Alternate System)
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LGP = W/GWSD Where: GW= S= D= W= return)
Grate width (fixed) less width of side layer (made up of fired pellets) Grate Speed Green Pellets density (manual set) Weight rate of green pellets feed to machine (measured total less green fines
Substituting to solve for Total Bed D epth, LT LT= LHL + W/GWSD
about 400- 450 mm
Using SI units of measurement (CGS system) L= W= G= S= D=
Millimeters (mm) Metric Tons/Hr (t/h) M (Meters) M/min 3 MT/meter = about 2.4
LT = LHL + K1 W GwSD
Where K1 is a constant of dimension “mm”
Value of K1: K1 =
1000 mm/M 60 min Hr
or K1 = 16.666 .
Then combine dimensional constant K 1 with Gw for a dimensionless constant K2
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The DCS compares the bed depth with its set point bed depth and modifies the grate speed accordingly through the variable frequency drive. As green pellet feed rate is increased, the calculated total bed depth will exceed the set point and the grate speed is increased proportionally. Conversely, for a decrease in green pellet feed rate, the calculated total bed depth is less than the set point and the grate speed is decreased proportionally. The machine speed varies continuously to maintain the set point bed depth. In the event of a loss of green pellet feed, the operator must take action. The course of action taken by the operator will depend on the cause of the loss of green pellet feed, as well as the overall needs of the plant. This area is covered thoroughly during the training phase of plant startup. An alarm, differentiated from other alarms by tone and volume, indicates loss of feed to the machine. 7.4.2
Process Fan Protection The five (5) process fans: • • • • •
Windbox Recup Fan (B42005) Updraft Drying Fan (B42006) Cooling Air Fan (B42004) Windbox Exhaust Fan (B42007) Hood Exhaust Fan (B42008)
Temperature elements located on both motor bearings and fan bearings are wired to the fan monitoring system (FMS), which then sends alarms to the HMI when a high or high-high temperature exists in any bearing. High-High temperature in a motor bearing or fan bearing is a fan shutdown. The motor current is indicated on the HMI. Fan and motor vibration is also monitored by the fan monitoring system at the inboard and outboard bearings. An alarm is activated to the HMI at high and at high-high vibration for any
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7.4.3
5
Updraft Drying Zone Hood Pressure A pressure transmitter (PT-05B0401) in the updraft drying zone hood provides the signal for the DCS controller that regulates the fan speed of the hood exhaust fan. A slightly negative pressure of about -1 to -2 mm water column is normally maintained. This pressure (PSL-05B0401) must be negative as a permissive to light the burners and after light off if a positive pressure occurs the DCS will force the burners to low fire after a time delay. The burners will go to low fire when the pressure at the cooling air duct is low (PSL-05B1335). Settings will be determined in the field. The DCS will “lock in” the low fire condition until reset at the HMI. A “Low Fire Bypass” switch is provided in the HMI to allow modulation of burners above low fire during startup. The fan inlet damper position and motor speed are indicated on the HMI and can be manually adjusted from the screen. Fan amps are also indicated on the HMI screen. The pressure set-point for (Loop No: PIC-0401, P&ID: R-05-1003, R-05-1017) is entered via the HMI. On an out of tolerance pressure condition, an alarm is displayed on the HMI.
7.4.4
Downdraft Drying Zone Hood Pressure A pressure transmitter (PT-05B0403) in the downdraft drying zone hood provides the primary signal that is transmitted to the DCS. Should the pressure in the downdraft drying zone increase, a damper (B54810) will open to discharge excess gas to the updraft drying hood. If the downdraft drying hood pressure continues above the desired set-point, the Downdraft drying bleed off damper (B54809) will open to bleed gas to the Hood Exhaust ESP (Loop No: PIC-0403, P&ID: R05-1003). Set-point pressure is normally maintained at a slightly negative value of about -3 mm water column.
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A pressure transmitter (PT-05B0602) in the second cooling zone hood sends a signal to the DCS, which compares the signal with the set-point and accordingly regulates the updraft drying fan speed (Loop No: PIC-0602, P&ID: R-05-1008). Normal set-point pressure for the second cooling zone is -4 to -9 mm water column. The fan inlet damper position can be manually adjusted from the HMI. The set-point pressure is entered via the HMI. In the event of an out of tolerance pressure condition, an alarm is displayed on the HMI. As long as the measured temperature at the updraft drying gas header (TE-05B0407) does not exceed the set-point for fan protection purposes (the set-point temperature is below maximum fan structural temperature), the second cooling isolation damper (B54828) remains in the open position and the updraft drying bleed-in damper (B54806) will modulate as needed. If the gas temperature continues to rise after the primary bleed-in damper is fully open, the DCS will then start closing the isolation damper (B54828) to reduce the flow of hot gas mixing with the ambient bleed-in air (Loop No: TIC-0407, P&ID: R-05-1003 & R-05-1008). Set-point temperature for fan protection is about 270°C. The fan speed and position of the bleedin damper, the duct damper and the UDD fan inlet damper are shown on the HMI. Motor amps are also displayed on the HMI. The set-point temperature for fan protection is entered via the HMI. In the event of an out of tolerance temperature condition, an alarm is displayed on the HMI. 7.4.6
Downdraft Zone Windbox Pressure The pressure in the firing zone windboxes is determined by the burnthrough temperature control and is not directly controlled. Windbox exhaust duct pressure control (PIC-05B1821) is provided. There is an option for ratio
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A pressure transmitter (PT-05B0405) in the updraft drying duct sends a signal to the DCS, which compares the signal with the set-point and accordingly regulates the updraft drying bleed-off damper (B54807) (Loop No: PIC-0405, P&ID: R-05-1003). The damper opens to relieve excess pressure under the grate to prevent any disturbances of the bed due to excessive undergrate pressure. Normal set-point pressure is about 500 mm water column. The set-point for the pressure is entered via the HMI. In the event of an out of tolerance pressure condition, an alarm is displayed on the HMI. The position of the bleed off damper is shown on t he HMI. 7.4.8
Wind box Recuperation Fan Temperature A thermocouple (TE-05B1235) located on the downstream side of the wind box recuperation fan sends a signal to the DCS, which compares the signal with the set-point and accordingly regulates the two bleed-in dampers (B54808-1, 2) (Loop No: TIC-1235, P&ID No. R-05-1012). The dampers allow ingress of ambient air at the inlet side of the wind box recuperation fan if the temperature rises above the set-point temperature. The position of the bleed-in dampers is indicated on the HMI. The temperature set-point for (TIC-05B1235) is entered via the HMI. On an out of tolerance temperature condition, an alarm is dis played on the HMI.
7.4.9
Burnthrough Temperature Two thermocouples are located in windbox 22 (TE-05B0731) (TE-05B0732). The temperatures are transmitted to the DCS where the temperatures are averaged and compared with the set-point. The DCS then regulates the windbox recuperation fan speed, increasing fan speed as necessary
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7.4.12 The DCS sends the master burner permissive, ready for purge, and at purge flow signals to the Main Panel. Details of these signals can be found in the Burner Operation section of the Operating Manual and the vendor’s burner operation ma nual. All downcomer temperatures are monitored for each burner. These same temperatures are available at the DCS. A purge and burner restart must then be completed if temperatures are below the auto-ignition temperature at any burner or zone. 7.4.13 The firing zone is heated with 38 burners. Each burner can be controlled individually. The operator can select oil or gas firing, with separate selector switches available on the main burner panel. In minimum flow position, the burner light-off is allowed as long as permissives are satisfied. The low fire indicating position is available to the DCS. Normally the furnace is started with oil and switched over to gas once control temperatures are maintained. Double block valves are used for both oil and gas for burner management. Refer to the vendor’s operation manual for specifics of this control and interlocking. The combustion system uses combustion air, ambient cooling pilot air, and atomizing air. The burners turn down by reducing fuel flow and run excess air operation. Cooling Air is maintained to the burners at all times, whether the burners are firi ng or in standby. The pressure both high and low are monitored by the burner management system. Refer to the vendor’s operation manual for specifics of this interlocking. The system run permit is removed if: Emergency Stop is pressed, Combustion Air blower is not running, Main Combustion Air pressure is low, atomizing air pressure is low, or pilot air pressure is low , fuel pressure is low or any safety
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7.4.14 Lintel Cooling Surge Tank Level A level transmitter (LIT-05B2701) sends a signal to the DCS, which compares the signal with its set-point and accordingly regulates the throttling valve (LV-05B2701) for make-up water (Loop No: LIC-2701, P&ID No: R-05-1016). For normal operation only a relatively small quantity of make-up soft water addition is required. The Lintel Cooling Tank level set-point is entered via the DCS HMI. Lintel Cooling Pumps (B41101-1, 2) supply lintel water through the two Lintel Cooling Water Heat Exchangers (B31201-1, 2) to the furnace lintels, baffles and hood seals. The temperature of the lintel water is monitored and alarmed. (TE-05B2709) In the event of an emergency condition where the water temperature (TE-05B2704) from the furnace lintels is too high, the DCS will open a valve (TV-05B2704) to introduce emergency makeup water from the emergency head tank into the furnace lintel cooling water supply header. When the emergency water valve is open the lintel cooling water storage tank could overfill and the water may temporarily overflow to drain. It should be an operator action to close this emergency valve when it has opened for any reason. Cooling water distribution must be balanced using manual valves and observing the collection b oxes. The emergency head tank is only used until the emergency standby generator can be started to run the lintel cooling water pumps. 7.4.15 Machine Discharge Hopper Level Load cells sense the weight (LIT-05B0305) of fired pellets in the discharge hopper. A level transmitter sends the load cell signals to the DCS, which compares the signal with the set-point and varies the speed of feeders (B55017-1, 2). This control need not be overly tight; the bin level should be allowed to float up or down. A proportional or gap control scheme should be used for this controller. The set-point is entered via the HMI.
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second set (firewater system) (TV-05B0315) at 150°C. The set-points may need to be reset during startup. All of the above mentioned automatic spray water temperature controls should have some amount of deadband programmed into the set-points to minimize cycling the valves. Additionally there is a pair of infrared temperature detectors (TE-05B0315) for belt fire protection above the belt itself downstream of the discharge chute which send pellet/belt temperature readings to the DCS. These signals should drive logic which will turn on the second set of belt sprays (firewater system) (TV-05B0315) to provide quench water when high temperatures are detected. The temperature set-point for the pellet/belt temperature control is dependent on the limits of the selected belt material. A specific alarm should display on the HMI to indicate a high temperature has been detected on the belt by these sensors and that the spray valve is open. Once opened by these sensors, it should require operator action to close the spray valve and reset the system.
7.4.17 Indurating Machine Drive Control A vendor supplied control system interfaces the DCS and the machine drives. Signals are sent between these systems to achieve control and monitoring. The indurating machine drive can be controlled from four locations, with only one location in control at any one time. An indicator light on each of the machine bridge, pallet change and drive station indicates when that station has control of the grate. 7.4.18 Control from the Control Room The DCS provides start/stop control through HMI screens. The DCS provides a speed reference signal to the variable frequency drive from the machine speed/bed depth controller. 7.4.19 Control from the Machine Bridge Control Station
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The pallet change station operator requests the DCS operator to give the pallet change station control of the machine. The DCS operator gives control to the pallet change station by clicking on the appropriate control area of the HMI screen. The DCS sends a signal to the pallet change control system signifying to the variable frequency unit that the pallet change station can take control. The pallet change station operator takes control when the “Control Active” Light is on. The variable frequency unit also sets the VF control signal circuits to accept jog forward and jog reverse signals from the pallet change station control panel. The speed of the machine is controlled by a preset speed signal in the variable frequency unit. Change-Out Mode: The operator will use the HMI “Change-Out Mode” selector to choose “Replace, Remove, Load or View” after turning the Pallet “On-Off” selector to “On” - Pallet Change Station control. Replace Mode: The operator is prompted to “Enter Pallet ID to be inserted” and the operator presses “ENTER" after keying in the ID number. For Remove Mode: Remove multiple pallets from the machine after fir st ID number is entered. For Load Mode: The pallet ID must be entered by the operator. After the first pallet is loaded, the operator can load other pallets in sequence. View Mode: The operator views the pallet stack. Data displayed is Position #, Pallet #, and the value of Sag. When the pallet change station operator has completed his operating task, he calls the DCS operator and informs him, and then turns the Pallet “ On-Off” selector to “Off”.
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The pallet sag measurement is recorded as it passes the Sag Monitor laser distance detector. The sag measurement is recorded in the Indurating Machine PLC and is tabulated for each of the respective pallet positions. The data is available on the local Touchscreen Unit. Sagging pallets are disassembled. The center casting is reversed. The pallet is then reassembled. The operator must periodically replace pallets that have deformed beyond design limits. 7.4.23 Hood Seal Flow The hood seal flow is automatically controlled with t he fan inlet damper. There is a cross tie to the combustion air fans with crossover dampers (B54812). These dampers only open when the combustion air blowers fail. Normally these dampers are closed. (Revision may occur – See Latest Design) The dampers open to keep air going to the burners when there is a combustion air failure. Hood seal flow control is designed to keep a low differential pressure between the hood seal pressure (PT-05B0601) and the furnace pressure (PT-05B0610). Hood seal fan inlet damper (B42009A) is controlled by a flow controller (Loop No: FIC-0611, P&ID: R-05-1008) which receives a differential pressure set value from a pressure controller (Loop No: PIC-0610, P&ID: R-05-1008). Hood Seal Fan flow controller (FIC-05B611) is limited to 30% minimum to maintain the seal under all conditions. For added protection, the hood seal fan has emergency power available. 7.5
Burner Management System The BMS provides furnace operational safeguards. The operational safeguards are implemented through hard-wired circuitry, interlocking safety devices, combustion safeguards and a Safety PLC. The BMS is designed to comply with NFPA 86:2011—Standard for Ovens and Furnaces. The BMS will perform only the burner management system functions listed. No Combustion Management System (CMS) functions (air/fuel ratio, flow control, temperature control, etc.) will be implemented as part of the BMS.
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Operational status and configuration of the BMS is available through Operator Interface Terminals (Human / Machine Interfaces). A total of two Human / Machine Interfaces (HMI) devices are provided, one located at the Main Control Panel (North Side) and one on the Remote Operator Interface panel (South Side). Communications between the HMIs and the BMS’s central processing unit are implemented through a ProfiNet star topology. Access to the BMS’s operational data values by the customer’s DCS system can be accessed through this network. Note: The Remote I/O ProfiNet network and the HMI/DCS ProfiNet networks are physically separate networks. 7.5.1
Control System Functions The control system functions are all provided new. The functional scope of this system includes the following items: Burner Flame Safety Excess Temperature Limit Interlocks 1400 °F Bypass Interlocks Combustion Safeguards Flame proving and monitoring Master Fuel Trip Relay Purge interlocks and timing Safety shutdowns Status monitored by BMS Combustion Control Ignition and Shutdown of burners Operator Interface Burner/equipment mode & status Burner/equipment alarms BMS control data entry
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The BMS circuitry is designed to shut off fuel to the burner system, by removing power (holding medium) to the Safety Shutoff Valves, through one or more of the interlocking safety devices, combustion safeguards or operating controls. Each hardware component and the overall operation of the burner management system are described in detail below: 7.5.4
Excess Temperature Limit Interlocks The furnace consists of eight control zones, each equipped with an Excess Temperature Limit Interlock (ETLI) controller. All E TLI safety devices will be mounted on the Main Control P anel. The ETLI controller is a panel-door-mounted, FM-approved temperature switch. The controller output contact opens whenever the thermocouple input indicates a temperature greater than a set point value. The output contact remains de-energized until both the temperature is below set point and the controller has been manually reset.
7.5.5
1400 ˚F (760 ˚C) Bypass Interlock A 1400°F Bypass Interlock is provided for each of the eight furnace control zones. The 1400 °F Bypass Interlock devices will be mounted on three of the six Remote I/O Control Panels. The 1400 °F Bypass Interlock indicates, by relay contact closure to the Safety PLC that the temperature of the associated control zone is above 1400 °F. Burners within a zone may be ignited only following the completion of a furnace purge cycle or if the 1400 °F Bypass Interlock indicates that the control zone temperature is above 1400 °F.
7.5.6
Manual Emergency Switches Mounted at each control location are Manual Emergency Switches, labeled Fuel-Stop, that are hard-wired into the BMS circuitry. The contacts of the switches are arranged in series such that operation of any Manual Emergency Switch removes power to the Safety Shutoff Valves for ALL burners (oil, gas and pilot) wit hin the system.
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All Remote I/O for the F-CPUs is implemented using Siemens S7-300 ET 200M Distributed I/O Devices which employ Siemens S7-300 Fail-Safe and Standard I/O modules. Communication of the module I/O data to/from the F-CPUs occurs over a ProfiNet communication ring. The Safety PLC is responsible for control of pre-ignition furnace purge, burner ignition; flame monitoring and BMS related alarm detection. The Safety PLC can interrupt power to the Safety Shutoff Valve(s) in the event of a shutdown condition, if a device failure is detected or an operational system-stop control is issued. 7.5.9
Remote Push Button Stations A remote push button station is supplied for each burner. Each push button station contains push buttons and status lamps for control of the individual burner to which it is associated. All push button stations contain the same discrete arrangement of devices, which are as follows: − Fuel-Stop Push Button − Local / Remote Selector Switch − Gas / Oil Selector Switch − Start Permissive Ready Indicator Lamp − Burner Start / On Illuminated Push Button − Pilot On Lamp − Burner Stop / Flame Fail Illuminated Push Button − Low Temperature Bypass Active Lamp
7.5.10 Human / Machine Interfaces (HMI) Operational status and configuration functions are available through the Human / Machine Interfaces (HMI). The system includes two HMI, each executing the same program. The HMI program shall include the following pre-engineered BMS graphic displays at a minimum: − Overview of BMS status − Purge Cycle status and control. − Burner Status & Mode − Igniter Status − Master Fuel Trip Status
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The main pilot fuel gas pressure is monitored using high and low pressure limit switches (customer supplied) mounted to the main pilot fuel gas supply. These limit switches are connected to discrete inputs of the Safety PLC. The Safety PLC continuously monitors the discrete inputs and will shut off power at all Remote I/O discrete output points connected to the pilot gas blocking valves and SSOV’s if either the high or the low pressure limit switch input is detected to be de-energized. The fail-safe values of the Remote I/O point to which the main pilot gas pressure switches are connected is de-energized. 7.5.15 Combustion Safeguard The Safety PLC monitors the Combustion Safeguards for the presence of flame at each burner. The Safety PLC will turn off the discrete Remote I/O output points connected to an individual burner’s pilot gas SSOVs, where the Combustion Safeguard at that burner has failed or has reported the absence of a flame signal for more than 5 seconds and the and the 1400 °F Bypass Interlock indicates that the temperature of the control zone is below 1400 °F. The fail-safe value of the Remote I/O points to which the Combustion Safeguard signals are connected is 0V (flame loss). 7.5.16 Main Burner Element Fuel Gas Limits The main fuel gas supply consists of a header at each side of the furnace. There are no SSOVs located on the main fuel gas header that are controlled by the BMS. A connection to the main fuel gas supply header, for each burner, provides primary gas to each burner. Each burner’s primary gas supply is isolated from the main fuel gas supply with two, series connected, automatic Safety Shutoff Valves (SSOVs). The de-energized state of the primary gas SSOVs is closed. The fail-safe state of the Remote I/O points t o which the SSOVs are connected is de-energized. Power to each burner’s primary gas SSOVs is dependent upon the following: 7.5.16.1
Manual Emergency Stop (Fuel-Stop)
The Manual Emergency Stop is hard-wired to interrupt power to the primary gas SSOVs of all burners.
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The main fuel gas pressure is monitored using high and low pressure limit switches (customer supplied) mounted to the main fuel gas supply. These limit switches are connected to discrete inputs of the Safety PLC. The Safety PLC continuously monitors the discrete inputs and will shut off power at all Remote I/O discrete output points connected to the fuel gas SSOV’s of all burners if either the high or the low pressure limit switch input is detected to be de-energized. The fail-safe value of the Remote I/O points to which the fuel gas pressure limit switches are connected is deenergized. 7.5.16.5
Combustion Safeguard
The Safety PLC monitors the Combustion Safeguards for the presence of flame at each burner. The Safety PLC will turn off the discrete Remote I/O output points connected to an individual burner’s primary gas SSOVs, where the Combustion Safeguard at that burner has failed or has reported the absence of a flame signal for more than 5 seconds and the and the 1400 °F Bypass Interlock indicates that the temperature of the control zone is below 1400 °F. The fail-safe value of the Remote I/O input points to which the Combustion Safeguard signals are connected is 0V (flame loss). 7.5.16.6
Atomizer Position
Limit switches are mounted to the burner body (of each burner) and provide indication to the Safety PLC of the burner’s atomizer position. The Safety PLC monitors the position of all burner atomizers and will remove power to the primary gas SSOVs of any burner in which the selected fuel mode is ‘gas’ and the atomizer position is not full y retracted. 7.5.17 Main Burner Element Fuel Oil Limits The main fuel oil supply consists of a header at each side of the furnace. There are no SSOVs located on the main fuel oil header that are controlled by the BMS. A connection to the main fuel oil supply header, for each burner, provides fuel oil to each burner. Each Burner’s fuel oil supply is isolated from the main fuel oil supply with two, series connected, automatic Safety Shutoff Valves (SSOVs). The de-energized state of the fuel oil SSOVs is closed. The fail-safe state of the Remote
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Remote I/O output points connected to the individual burner’s fuel oil SSOVs. Failure of the thermocouple input results in an under-temperature (temperature is below 1400 °F) indication by the controller. The Safety PLC will perform the required action based on the status of the Combustion Safeguard at each individual burner within the control zone. Compressed Air Supply pressure
The Compressed Air Supply pressure is monitored using high and low pressure limit switches (customer supplied) mounted to the compressed air supply. These limit switches are connected to discrete inputs of the Safety PLC. The Safety PLC continuously monitors the discrete inputs and will shut off power at all Remote I/O discrete output points connected to the fuel oil SSOV’s if either the high or the low pressure limit switch input is detected to be de-energized. The fail-safe value of the Remote I/O points to which the compressed air supply pressure limit switches are connected is de-energized. Main Fuel Oil Pressure
The main fuel oil pressure is monitored using high and low pressure limit switches (customer supplied) mounted to the main fuel oil supply. These limit switches are connected to discrete inputs of the Safety PLC. The Safety PLC continuously monitors the discrete inputs and will shut off power at all Remote I/O discrete output points connected to the fuel oil SSOV’s of all burners if either the high or the low pressure limit switch input is detected to be de-energized. The fail-safe value of the Remote I/O points to which the fuel oil pressure limit switches are connected is deenergized. Main Fuel Oil Temperature
The main fuel oil temperature is monitored using high and low temperature limit switches (Customer supplied) mounted to the main fuel oil supply. These limit switches are connected to discrete inputs of the Safety PLC. The Safety PLC continuously monitors the discrete inputs and will shut off power at all Remote I/O discrete output points connected to the fuel oil SSOV’s of all burners if either the high or the low temperature limit switch input is detected to be de-energized. The fail-safe value of the Remote I/O points to which the fuel oil temperature limit switches are
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7.5.18 Pre-Ignition Purge Prior to powering any fuel or oil SSOVs within a control zone who’s temperature is less than 1400 °F, a pre-ignition purge of the entire pelletizing furnace chamber must be performed. The pre ignition purge is performed to remove all flammable vapors and gases from the heating chamber during a shut-down period. The system must be purged with fresh air for a minimum of five (5) volumetric air changes in the heating chamber prior to introducing a source of i gnition. The Safety PLC will generate a “Ready to Purge” indication for each of the eight control zones. The Ready to purge indication results from the all of the following conditions being satisfied: All four of the SSOVs located on the main pilot gas headers are closed. − Both primary gas SSOVs, at each burner in the control zone, are closed. − Both fuel oil SSOVs, at each burner in the control zone, are closed. − The fuel gas flow control valve, at each burner in the control zone, is in the low-fire position. − The fuel oil flow control valve, at each burner in the control zone, is in the At Low-Fire − position. The Ready to Purge status of all eight control zones can be visually monitored on the HMI. Note: The Ready to Purge and other status registers that are available to be read from the Safety PLC, by the customer DCS system, over the ProfiNet HMI/DCS network, are listed within Section 5 of this document. A Start Purge command is init iated by an operator pressing the ‘Start Purge’ soft-button on the HMI screen. The customer DCS is expected to prove purge air flow and supply an “At Purge Flow” indication as a discrete/hard-wired input to the Safety PLC. When all eight control zones are “Ready to purge” and the “At Purge Flow” indication is received by the Safety PLC, the Safety PLC will initiate a pre-ignition purge sequence. When the pre-ignition purge sequence has been initiated, the Safety PLC will set the “System Purge Status” and eight individual “Zone Purge Status” registers to ‘Active’. The Safety PLC will then start will start two internal timers: Purge Timer
The Purge Timer will accumulate time as long as the System Purge Status is
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Status register is ‘Complete’, burners within that zone may be may be ignited, given their “Burner Start Permissive” is also active. The Burner Start Permissive are written to the Safety PLC from the customer DCS. When an attempt to ignite a burner within a control zone is made, the associated Zone Purge Status register is set to ‘Inactive’. Loss of any Ready to Purge limit while the Zone Purge status is ‘Complete’ will cause an alarm is displayed on the HMI indicating this condition and the Zone Purge Status is set to ‘Inactive’. The transition of any of the Zone Purge Status registers to ‘Inactive’ causes the System Purge Status to be set to ‘Inactive’. 7.5.20 Burner Ignition For each control zone, burners may be ignited if their “ Burner Start Permissive” is TRUE and any of the conditions are satisfied: 1) 1400 °F Bypass Interlock is indicating that the zone temperature is above 1400 °F. 2) The Zone Purge Status is ‘Complete’. 3) The status of at least one burner w ithin the control zone is “Released to Control”. Burner Ignition can be individually initiated via the Remote Push Button Stations or using the individual “Burner Start” soft-buttons on the HMI. An Automatic Ignition Sequence to start all burners can be initiated using the “Start All Burners” soft-button on the HMI. When the “Start All Burners” soft-button is pressed, not all burners are start at once. The ignition sequence for one burner in each control zone will be started immediately, with additional burners in each zone stared every 3 seconds thereafter, until the ignition sequence has been started for all burners within all control zones. Burners will be started in order of their associated ‘wind box numbers’. Starting with the “A-North” burner with the lowest wind box number within the group and alternating next to the “A-South” burner, followed by “B-North” and lastly “B-South”. The same sequence is repeated (if necessary) for the next set of four burners within the group. Any burners in which the corresponding Burner Start Permissive has not be set by the DCS will be excluded from the Automatic Ignition Sequence. Failure of a combustion limits during ignition will result in termination of ignition sequence(s). A list of the combustion limits and a description of the corresponding effect upon the ignition sequences is as follows:
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energizing the burner’s pilot gas SSOVs and the burner’s ignition transformer. The Safety PLC will set the burner’s status to “Pilot Starting”. The PLC will monitor the status of the burner’s Combustion Safeguard for a ‘Flame Detected’ signal. The trial for ignition period is defined as the time from which the pilot gas SSOV is energized and a ‘Flame Detected’ signal is reported by the Combustion Safeguard. The trial for ignition period is set within the Safety PLC not to exceed 15 seconds. Failure of the Combustion Safeguard to report a ‘Flame Detected’ signal within the trial for ignition period will cause the Safety PLC to remove power from the burner’s pilot gas SSOVs and ignition transformer, annunciate an alarm on the HMI and change the burner’s status to “Faulted”. When a ‘Flame Detected’ is received from the burner’s Combustion Safeguard (within the trial for ignition period), the pilot flame will be given time to stabilize. The pilot flame stabilization time is configurable from the HMI. Following the pilot flame stabilization time, the Safety PLC will apply power to the burner’s primary fuel gas SSOVs (or fuel oil SSOVs depending on the burners fuel selection), given that the fuel flow control valve is in the “At Low Fire Switch” p osition. The Safety PLC will set the burner’s status to “Main Flame Starting”. The DCS must command the fuel flow control valve to a position such that the Saf ety PLC receives contact closure of the valve’s “At Low Fire Switch”. The “At Low Fire Switch” must be maintained until the Safety PLC has changed the burner status to “Released to Control”. Failure to maintain the “At Low Fire Switch” will result in the Safety PLC shutting down the burner. After the main fuel gas/oil SSOVs have been opened, the Safety PLC will allow the main burner flame time to stabilize. The main flame stabilization time is configurable from the HMI. Once the main flame stabilization time has expired, the Safety PLC will set the burner’s status to “Released to Control”. At this point, the Safety PLC will remove power from the burner’s pilot gas SSOVs, thus turning off the pilots. When the burner has reached the “Released to Control” state, the DCS can command the corresponding fuel control valve away from the “At Low Fire” position and control fuel flow to the
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4) The pilot flame is will be given time to stabilize. The post-purge pilot flame stabilization time is configurable from the HMI. 5) The burner’s fuel oil SSOVs are de-energized by the Safety PLC. 6) The Safety PLC will set the burner’s status to “Post-Purge Active”. 7) The DCS should begin driving the fuel oil flow control valve to the high-fire position. 8) The Safety PLC opens (energizes) the burner’s fuel oil purge valve. The amount of time that the fuel oil purge valve is held open is configurable on the HMI. 9) Once the fuel oil purge valve time has expired, the fuel oil purge air valve is closed. 10) The Safety PLC de-energizes the burner’s pilot gas SSOV’s. 11) The burner’s status is set to “Stopped”. 8.0
PRODUCT SCREENING –AREA 6
Product screen feed bin (B43611) is used to distribute fired product pellets to the product screens (B43522-1, 2). This separation occurs as pellets pass through the screens. Product pellets go to the P-12 (B43047) Product Conveyor. Hearth layer chute pellets (12.5 x19mm) go to HL-12 (B43071) hearth layer conveyor which feeds HL-13, HL-14 to the Hearth Layer Bin (B54013). The emergency product vibrating feeder is programmed to operate based on the product screen feed bin level or the hearth layer bin level. If the product screens are down, the feed to the screens is stopped by closing the screen feed gates. The emergency gate to feed pellets to the HL-13 (B43776) is opened. A software switch now allows the emergency product feeder run at based on hearth layer bin level. An emergency hearth layer hopper is fed by mobile equipment. The reclaimed material travels to the Hearth Layer Bin (B54013). Product pellets on P-12 (B43047) are measured by belt scale (B55221) (WIT-06B0122) and supply the JSPL Product Conveyor. Screened Sinter Fines travel to SF-11, SF-12 to the Sinter Fines Loading Bin (B43520). A sinter fines sampling system (B55402) extracts pellets periodically. The pellets are recovered
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9.1
Hood Exhaust ESP (B50025)
9.1.1
System Description
5
This is flue gas cleaning system for cleaning the gases from Hood Exhaust circuit of Pallet plant. The system consists of ESP model TE-1. The hot gases having maxi mum temperature of 105°C is allowed to pass through the inlet nozzle. Gas distribution plates inside the nozzle ensure equal distribution of the gases through different parallel paths formed by the arrangement of collecting plates and e-Tubes. The collecting area is divided into four sections. Each section is fed by TR set of 900 mA (Total 4 Nos. for chamber-1 & 4Nos. for chamber-2), mounted on the ESP rooftop. High voltage of 120 KV DC (peak value) is applied to the e-Tubes. The ash gets collected on the collecting plates. The collecting plates and e-Tubes are continuously rapped from the top by rappers whose operation is controlled by PLC based Microtapper panel located in the control room. Due to rapping, the ash collected on collecting plates is dislodged and collected in the hopper. The ash is discharged to the dust discharge equipment through hopper. 9.1.2
Control And Interlock Provided For The System Mechanical door interlock system The system ensures that no person can enter inside the ESP unless all the Transformer Rectifier units are de-energised, isolated and grounding switches of TR sets GS-1 to GS-8 (For chamber-1 & chamber-2) are in ESP grounded position. Thermostatically controlled Insulator Heater 700 W air heater is provided around each support insulator. A thermostat is provided in the pent house (TC-5 & TC-11) for chamber-1 & chamber-2 to maintain the temperature at 85°C. Thermostatically controlled hopper heaters Hopper heating pads (HH-1 to HH-8) are provided in bottom one-third part of the hoppers to avoid condensation & ensure free flow of dust. The heating pads are thermostatically controlled
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Stop Sequence Purge air heater OFF If the heater is OFF, then the blower will be switched off after a time delay of 5 sec approximately. Purge Air heater Thermostat (TC-6 & TC-12) is provided in the purge air heater to protect the purge air heating elements from over temperature 9.1.4
MTP (Micro Tapper Panel) Rapper control system is designed specifically for electrostatic precipitator application. This rapper control system is designed to be use with electrical solenoid type impact Rappers. These Rappers are also called as Thermax impulse gravity impact (TIGI) Rappers. Rapping system is an “ONLINE“operation (i.e. Rappers can be turned ON, when TR sets are energised.) The working principle of the rapping system is as follows: A short duration pulse of high current amplitude is applied to the rapper solenoid coil. Once the coil is energized the rapper rod inside the coil lifts up. The longer the duration of the pulse the higher is the lift. On withdrawal of pulse the rapper rod falls down by gravity. The falling rod makes impact with the e-Tube/collecting electrodes causing the dust accumulated on it to dislodge and maintain their electric field. The rapper coils are energised by MTP through a DC controller individually. The DC controller provides a high current & high voltage pulse of short duration. The +Ve & -Ve ends of the dc controller get connected across each rappers thus selected rapper coil is energized and makes impact on the respective electrode. Rapping system shall be put ON all the time when ID Fan is running irrespective of ESP is charged or not.
9.1.5
Dust conveying system Dust conveying system shall be ON (Running) all the time. If dust conveying system tripped /
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In operation, the high potential between the negative & grounded electrodes ionizes the surrounding gas & produces a large number of negative ions. (This is known as corona effect.) These negative ions collide with the dust particles & impact their negative charges to them. The negatively charged particles then are drawn to the grounded collecting plates, from which they are periodically dislodged by means o f a rapping mechanism. 9.1.6
Voltage Control As the dust laden flue gas passes through the collecting electrodes and e-Tube, the ESP can be considered as a capacitance having variable di-electric strength. The di-electric strength varies due to changing parameters of the flue gases. The high D.C. voltage applied to the ESP has to be continuously adjusted to minimize sparking across the e-Tubes and collecting plates. The voltage controller provided in the Transformer Rectifier control cabinet senses the current feedback from the ESP and does the following functions. i) It maintains the voltage across the ESP at the spark threshold level in all the conditions to achieve maximum efficiency. ii)
During no sparking conditions, maximum power is made available across the ESP.
iii) In case of spark, it brings down the voltage by preset value. The voltage is gradually raised to spark threshold level if no further spark is detected. iv) In case of arc it brings down the voltage to zero and blocks it for preset time. The voltage is restored to the preset value by fast ramp and t hen to the spark threshold level by slow ramp. 9.1.7
ESP Start Up Procedure Energise hopper heaters, insulator heaters & Purge air heaters twelve hours prior to flue gas passing through the precipitator from Motor Control Center. Start the dust discharge equipment below the Hopper. About one hour before the Furnace is fired, energize the e-Tube and collecting electrode
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9.1.9
5
Caution a) It is a must that initially, after shutdown of Furnace or initial charging, the ID fan should be run for at least one hour, to remove explosive gases, if any in ESP, before “Switching ON” the TR sets. b) It is a must that dust discharge equipment below ESP hopper must be running whenever I.D. fan is running. It is always to be ensured that there is no dust accumulation whatsoever in the hoppers. The dust accumulation in the hopper may damage the ESP internals. c) ESP hopper door to be opened, only after I.D. fan is stopped. This is necessary to avoid sudden ingress of fresh air in the hopper which contains dust wit h high carbon content. d) Dust discharge equipment shall be running all the time. e) Rapping system shall be ON (running) all the time when ID fan is running irrespective of ESP is charged or not. f)
Purge air system is not running then trip the TR sets.
9.1.10 Process Interlock Provision of upstream & downstream process / equipment interlock has been provided in the TRCC panel for tripping purpose. Generally such interlocks are process related & JSPL has to identify for tripping of TRCC in case of unhealthy condition. 9.1.11 Alarms Following alarms will be provided on Motor Control Centre: •
High ash level in the hoppers (for chamber-1).
•
Purge air blower tripped (for chamber-1).
•
High ash level in the hoppers (for chamber-2).
•
Purge air blower tripped (for chamber-2)
•
Spare.
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•
T/R set feeders : Supply ON & OFF Lamp.
•
Microtapper panel feeder : Supply ON & Off lamp.
•
Hopper heater 1 to 8 : On, Off & Temp. trip lamp.
•
Insulator heater 1 & 2 : On, Off & Temp. trip lamp.
•
Control transformer feeder : Control supply ON lamp.
•
Purge air blower feeder 1 & 2 : On, Off & over-load trip lamp.
•
Purge Air heater feeder 1 & 2 : Oc, Off & Temp. trip lamp.
•
Annunciator + Level switch feeder : Level high lamp for each level switch.
9.1.15 Transformer Rectifier Control Panel •
Mains on lamp.
•
HT on lamp.
•
Alarm / Trip lamp.
9.1.16 Microtapper Panel
9.2
5
•
Mains ON
•
Rapper ON
•
Rapper Fault
•
HMI Disply - 1) Rapper short circuit
•
Rapper open circuit
•
Rapper Fault Indication
Wind box Exhaust ESP (B50026)
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9.2.1.2 Thermostatically controlled Insulator Heater 700 W air heater is provided around each support insulator. A thermostat is provided in the pent house (TC-9 & TC-19) for chamber-1 & chamber-2 to maintain the temperature at 85°C. 9.2.1.3 Thermostatically controlled hopper heaters Hopper heating pads (HH-1 to HH-8 & HH-9 to HH-16) are provided in bottom one-third part of the hoppers to avoid condensation & ensure free flow of dust. The heating pads are thermostatically controlled (TC-1 to TC-8 & TC-11 to TC-18) for chamber-1 & chamber-2. The temperature is maintained up to 110°C. Max. (Adjustable). 9.2.1.4 Level switches in the hopper R.F. capacitance type level switches (LSH1 to LSH16) for chamber-1 & chamber-2 is provided in each hopper. The level switch operates when ash level inside the hopper rises & touches the level switch probe. The first set point level switch gives signal to the audio visual alarm annunciator provided in the Motor Control Center to indicate high ash level in the hopper & trips the TR Set. Even after tripping of TR Set, an ash continues to build up in Hopper, and If the high level alarm is persisting, an Auxiliary Contact High hopper level relay provided in MCC. it is recommended to stop the Furnace after one hour time delay. This prevents ash building up in the hoppers, which ultimately shorts the e-Tubes & collecting plates. Potential free contacts shall be provided in ACP to wire the same for Furnace tripping / stopping & signal t o DCS. 9.2.1.5 Purge Air Blower Purge air blower ensures positive air pressure inside the pent house with respect to ESP casing. The air flows along the inside surface of the support insulators thereby keeping the insulators clean. All the TR sets are wired for tripping in case the Purge A ir Blower Trips. Start Sequence: Purge air blower ON Then purge air heater will be started (start interlock of PAB with PAH) Stop Sequence: Purge air heater OFF If the heater is OFF, then the blower will be switched off after a time delay of 5 sec approximately.
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9.2.1.8 Dust conveying system Dust conveying system shall be ON (Running) all the time. If dust conveying system tripped / stopped, then all TR sets & al l dust discharge equipments shall be trip. 9.2.1.9 Dust discharge equipment If the dust discharging equipment stopped/tripped, then corresponding TR set shall be trip. 9.2.1.10
I.D. Fan interlock
If ash discharge equipment stopped or tripped, then ID fan to be stopped or tripped & signal to DCS to be provided. Provision has to be made for this interlock in Main Automation S ystem. 9.2.2
Theory Of Operation ESP construction & operation is based on the f act that dust particles are passed between a highly charged & grounded electrode. The particles get collected on the grounded electrode. Accordingly, the Thermax ESP is designed to: Apply a highly negative charge to gas-borne dust particles. Collect the particles on grounded metal plates, which are rapped periodically to dislodge the dust into hoppers. The particles are charged by rows of vertical high-voltage electrodes mounted in parallel frames. The frames are connected at the top to the negative terminal of a high-voltage DC power supply. The collecting plates (grounded electrodes) are parallel to the rows of e-Tubes & alternate with them -- i.e., plate, e-Tube frame; plate, e-Tube frame. In operation, the high potential between the negative & grounded electrodes ionizes the surrounding gas & produces a large number of negative ions. (This is known as corona effect.) These negative ions collide with the dust particles & impact their negative charges to them. The negatively charged particles then are drawn to the grounded collecting plates, from which they are periodically dislodged by means of a rapping mechanism
9.2.3
Voltage Control
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Start the Purge air blower from MCC. If purge air system is not working trip TR sets. Ensure all the level switches are swit ched “ON” and no annunciation is persisting on the MCC. Ensure that the Furnace and ID fans are running and flue gas temperature is above the acid dew point temperature. If the flue gas temperature is less than the acid dew point temperature then damp acid sludge will form on the precipitator internals, and scaling will take place. This will reduce the life of e-Tubes and collecting electrodes. If dust conveying system or dust discharge equipment trips / fail, then tri p I.D. Fan After the flue gas temperature reaches above the acid dew point temperature the TR units should be energized. Ensure that TRCC panels are in Auto mode before swit ching on. After all the TR sets are energized the electrical meter readings should be observe 9.2.5
Precipitator Shutdown During normal Furnace shutdown the TR sets should be de energized before I.D. fan is switched off. After all the TR sets are de-energized the e-Tube and collecting electrode rappers should be maintained in service for approx. two hours. Switch `OFF’ purge air blower after I .D. Fan is switched `OFF’ & TR sets are de-energized Dust discharge equipment should be in service for one hour after Microtapper panel is stopped.
9.2.6
Caution It is a must that initially, after shutdown of Furnace or initial charging, the ID fan should be run for at least one hour, to remove explosive gases, if any in ESP, before “Switching ON” the TR sets. It is musts that dust discharge equipment below ESP hopper must be running whenever I.D. fan is running. It is always to be ensured that there is no dust accumulation whatsoever in the hoppers. The dust accumulation in the hopper may damage the ESP internals. ESP hopper door to be opened, only after I.D. fan is stopped. This is necessary to avoid sudden
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9.2.9
5
Transformer-Rectifier control panel (Note: The following alarms will be indicated on the TRCC controller LCD display) •
Transformer oil temperature high alarm.
•
Transformer oil temperature high trip.
•
Transformer Buchlotz relay alarm.
•
Transformer Buchlotz relay trip.
•
SCR temperature high trip.
•
Over voltage trip.
•
Under voltage trip.
•
Thermal overload trip.
9.2.10 Following indications will be provided provided on Motor Control Centre Centre •
Incomer feeder : R, Y, B phase indicating lamp.
•
Breaker ON, OFF & TRIP
•
T/R set feeders : Supply ON, Off Lamp.
•
Microtapper panel feeder : Supply ON, Off lamp.
•
Hopper heater 1 to 16 : On, Off & Temp. Temp. trip lamp. lamp.
•
Insulator heater 1 & 2 : On, Off & Temp. trip lamp. lamp.
•
Control transformer feeder : Control supply ON lamp.
•
Purge air blower feeder 1 & 2 : On, Off & over-load trip lamp.
•
Purge Air heater feeder 1 & 2 : On, Off & Temp. trip lamp.
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9.4
5
LIT-3022 monitors the level of Windbox Exhaust ESP Sump Sump and for low sump level, process water is mixed into the sump which is controlled by LV-3022 (Loop No: LIC-3022, P&ID No. R-05-1011). Low low level of the sump w ill stop the Windbox Exhaust sump pumps. Housekeeping scrubbers and a baghouse are used to collect fugitive dust:
9.5
Scrubbers
9.5.1
Machine Discharge Scrubber (B50005) This scrubber includes a Machine Discharge Scrubber Fan, and local water sprays. The water valve (XV-07B6262) will open any time that t he scrubber is in operation. LIT-6206 monitors the level of Machine Discharge Scrubber Sump and for low sump level, process water is mixed into the sump which is controlled by LV-6206 (Loop No: LIC-6206, P&ID No. R-071002). Low low level of the sump wil l stop the Machine Discharge Scrubber sump pumps.
9.5.2
Hearth Layer Bin Scrubber (B50007) This scrubber includes Hearth Layer Exhaust Fan, and local water sprays. The water valve (XV07B7262) will open any time that the scrubber is in operation. Similar to the ESPs, the wet discharge from these scrubbers is collected in sumps and pumped to the plant thickener. The baghouse dust is slurried and pumped to the thickener.
9.5.3
Product Screening Baghouse (B50006) includes a fan (B50006A) and dust handling valves (XV2626- 2627). The dust from product screening baghouse is collected in a sump. LIT-2017 monitors the level of Product Screening Baghouse Sump and for low sump level, process water is mixed into the sump which is controlled by LV-2017 (Loop No: LIC-2017, P&ID No. R-07-1004). Low low level of the sump will stop the Product Screening Baghouse sump pumps.
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Each set of pumps are one operating and one stand by. Each circulation loop provides heater controls (B48002-1, 2 & 3) for pumps (B41002-1, 2). Oil heaters heat oil to 125 degrees C and decrease oil viscosity to meet burner atomizing requirements. Primary pressure control for indurating machine circulating pumps (B41002-1, 2) is be accomplished utilizing primary pressure loop (Loop No: PIC-0234, P&ID: R-08-1002) with a secondary pressure loop (Loop No: PIC-0246, P&ID: R-08-1002). Oil Supply to the Indurating furnace and Additive Grinders, is from the fuel oil tanks. Oil composition is given below: Fuel Oil Properties Table 6.4.1 Furnace Oil, MV2 Composition, wt.%
Fuel Oil Composition Carbon Hydrogen Oxygen 84 11 0.5
Table 6.4.2 Characteristics Inorganic acidity Ash, % wt. Max Gross Calorific Value, cal/gm Density Densit y at 15°C 15°C Flash Point °C. Min Kinematic Kinemat ic Viscosity, Viscosi ty, centistokes centist okes @ 50°C 50°C Sediment, % wt , Max Sulfur, total % wt. Max Water content, % v/v, Max Pour Point, °C, Max
10.2
Compressed Air
Nitrogen 0.4
Sulfur 3.5
Fuel Oil Properties Grade MV2 Requirements Nil 0.1 10,000 Assume 0.95 66 125 - 180 0.25 4.0 1.0 27
Water 0.5
Ash 0.1
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Pumps in the plant that handle heavy iron ore slurries have flushed mechanical seals. Seal water supply system for wet grinding includes a Gland Seal Water Tank (B34031) and pumps (B41034-1, 2) producing water at 7.0 kg/cm2 or pressure determined by the supplier. Seal water supply system for other areas includes a Gland Seal Water Tank (B34030) and pumps (B41033-1, 2). The flow of process water to seal water tank is controlled by a level control valve LV-2306 (Loop No: LIC-2306, P&ID: R-01-1022) 10.8
Potable water for plant offices and associated areas is supplied by JSPL. Fire protection water is supplied from JSPL’s fire water supply system. A separate header system from the fire water supply is provided depending on the approval of local regulatory agencies. Normal fire water loop pressure is 7.0 k g/cm2.
10.9
Fuel Gas Gas is available to the burners. The burner system is selected for use on fuel oil or fuel gas but not both at the same time. Safety shutoff valves are connected to the appropriate burner management system. Fuel gas is for use only with the Indurating System. FUEL GAS PROPERTIES (To be confirmed by JSPL) Table 6.4.3
FUEL GAS PROPERTIES
Compound CO CO2
Unit % Volume % Volume
Value 25 6
H2
% Volume
13
CH4
% Volume
1.5
N2
% Volume
53
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10.10
5
Cooling Water
10.10.1 Area-1 Wet Grinding Cooling Water is supplied by cooling water pumps (B41060). The cooling water return goes to a cooling tower. Makeup water is supplied by JSPL. Make up water supply is controlled by a control valve LV2106 at the inlet of cooling tower basin based on cooling tower basin level (Loop No: LIC - 2106, P&I D: R-01-1021). Soft water make up to wet grinding cooling water surge tank (B35103) is controlled by a control valve LV0901 at the inlet of surge tank based on surge tank level (Loop No: LIC - 0901, P&ID: R01-1028). 10.10.2 Area-2 to 8 Cooling Water is supplied by cooling water pumps. The cooling water return goes to a cooling tower. Makeup water is supplied by JSPL. Make up water supply is controlled by a control valve LV0801 at the inlet of cooling tower basin based on cooling tower basin level (Loop No: LIC - 0801, P&ID: R-08-1008). Soft water make up to Service cooling water surge tank (B35102) is controlled by a control valve LV0891 at the inlet of surge tank based on surge tank level (Loop No: LIC - 0891, P&ID: R-011009). A closed loop system for service water is used in area 1 as well as in area 2 to 8. 11.0
CONTROL SYSTEM OVERVIEW & PHILOSOPHY
11.1
The control system shall consist of a distributed control system (Main Automation System) which interfaces with analog and discrete field signals. It is referred to generically as a Main Automation System but may in fact also incorporate and/or interface one or more programmable logic controller (PLC) systems for discrete logic functions and control of third party equipment.
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systems and variable speed drives have the capability to communicate directly to the plant control system, minimizing wiring and facilitating startup. Wherever possible, OPC can be used to reduce CPU loading of Main Automation S ystem. 11.2.4 Control Room and Process Control The process control and automation for the pellet plant and feed preparation areas are a combined system, placed into a central control room. Programmable logic controllers (PLCs) for motor control will be integrated with a distributed control system (Main Automation System) for process control and human/machine interface (HMI). The central control room is located in the same building as the indurating area office facilities. 11.3
CONTROL PHILOSOPHY
11.3.1 The control philosophy follows the control philosophy of existing Plant 1. 11.3.2 Screens showing interlocks and permissives should be provided for equipment as required to allow the operator to troubleshoot items not satisfied. 11.3.3 Main Automation System setpoints are switched from internal to external operation as needed. When an external setpoint is entered, the system will ignore the value calculated by the control algorithm. These modes can be referred to as CALCULATED SP and OPERATOR SP. Transfer between modes should be bumpless. 11.3.4 Motors, Drives and Valves The motor control philosophy is based on the referenced motor control schematics, R-00-1003 through R-00-1007. For LT motors run command will be single maintained output but for HT motors run command will be a pulse only. A switch at the motor shall be able to select ‘remote’, which enables the Main Automation System software to operate the motor, or ‘local’ which enables the motor to be started in the field by a
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‘Auto/Off/Man’ switch; ‘auto’ signifies automatic mode and when selected the motor responds to logical commands to run or starts as part of a group-start; ‘man’ indicates manual mode and the motor can be controlled by the individual HMI ‘pushbuttons’ When a group of drives have been group-started in ‘auto’, turning any particular drive in that group to ‘man’ will not stop that drive, but will only give the operator access to stop or restart that drive individually. However, if that drive is interlocked with other drives (usually to prevent the upstream equipment from continuing to feed the stopped item), the interlock will still be active, and stop the other equipment upstream. When in ‘auto’, there are two ways to stop a group of drives (usually conveyors). Either or both of these ‘stopping modes’ can be programmed, depending on the situation. ‘Programmed stop’, used to shut down a group of material feeding equipment in an orderly fashion and leaving it empty. In this mode, ‘group stop’ will first shut down the feed to the first item in the group; then wait until the next item runs empty, and stop it; and so on down the line until the entire group is stopped and left empty. ‘Immediate stop’, used to instantly stop material delivery from the group. In this mode, ‘group stop’ will stop all the items in the group simultaneously, but leaving the conveyors in the group full of material. In this case, the next ‘group start’ will restart all the items right away (or as quickly as starting power loading will allow). This mode must be selected with care, being sure that all the material handling items in the group are able to restart under full load. Immediate stop can be operated but immediate start mode is not recommended except for emergency. ‘Start/Stop’ Main Automation System pushbuttons or their graphic equivalent, are used to operate the motor in the ‘MAIN AUTOMATION SYSTEM-man’ mode. 11.3.5 Automated On-Off Valves In general, all automated on-off control valves are shown schematically on the HMI screens and except where explicitly noted will bring up a display when selected allowing the operator to manually control the valve position. Generally manual control bypasses any interlocks.
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11.4.1.1
5
All process pumps have the following logical attributes:
Pumps are normally started from the HMI screen manually as required; unless otherwise indicated below, pumps are not part of ‘equipment starting groups’, but are started individually ahead of time as required, and normally left on. After the pump is started from the MAIN AUTOMATION SYSTEM; and after a time delay, if the drive feedback indicates that the pump has been stopped other than by the operator, a ‘drive fault alarm’ sounds. On a stoppage due to a drive fault, the equipment must be put into HMI manual and stop selected to clear the fault before a restart can be initiated. If the vessel, which feeds the pump, reaches lowlow level (below the point where the low-level alarm sounds), the pump will shut down (or can not be started). High-high level from the vessel being pumped into is not an interlock to the pumps. The high-level alarm in that vessel only warns the operator of this impending possibility. Exceptions to this strategy are noted on the P&IDs. The accumulated run time for all process and lube pumps shall be recorded in the MAIN AUTOMATION SYSTEM (and be able to be displayed), so that the operator, if he has a choice, (or the MAIN AUTOMATION SYSTEM logic, if able to make the choice) can start the one in any group with the least service, or periodicall y change over to evenly distribute the wear. The total accumulated time can be reset at the M AIN AUTOMATION SYSTEM screen. 11.4.2 Process Pump Pairs with Automatic Backup Starts All process pumps in groups of two (one normally operating and one standby), which pump clear water or other non-settling process fluid will have the non-running, backup pump try to start automatically if the initially started pump has a drive fault alarm as described above and the pump is selected for MAIN AUTOMATION SYSTEM AUTO.
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Included with the reciprocating conveyor are both a hydraulic pump and hydraulic flushing motor drives. Control signals from the Main Automation System i nclude; Interlock-(Permit to run) Reciprocating Run Command Position the Cylinders Output Cooling Fan Run Heater Run Status Inputs to the Main Automation S ystem include: Flush Pump Filter OK Cooling Water Filter OK Main Pump Filter OK Local Maintenance Inputs to Main Automation System from JSPL Local Panel i nclude; Cylinder Forward Cylinder Reverse Cylinder Stop Wide Belt Run, Stop Pumps Start, Stop Remote, Maintenance Switch Reciprocating Conveyor Start, Stop Cylinder Speed Setting (4-20 mA) Wide Belt Speed Setting (4-20 mA) Reciprocating Conveyor Speed Setting (4-20 mA) Start Sequence: Start Double Deck Roller Screen (B43037E, B43037F) Start Wide Belt ( Machine is Running ) Active Horn 5 seconds Start Hydraulic Pumps Start Reciprocating Belt and prove at desired speed
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Each process slurry pumps or dust collection slurry pumps in Area 1 ,has water seals, controlled as follows: There is a flow switch in each seal water supply. If the flow switch does not register minimum flow, an alarm is set. This low flow alarm does not shut down the pump, but should be promptly attended to by the operator. 11.4.8 Conveyor Systems Standard Single Speed Conveyors Single speed conveyors are shown on Motor Detail 1 on R-00-1003. General Logic For Conveyors Conveyors can be operated in Automatic or Manual modes. Conveyor operation is conditional based on the status of the start permissives and run i nterlocks. Conveyor statuses (Ready, running, etc.) and alarms (zero-speed, belt side travel, fault, plugged chute, E-stop) are indicated on the HMI. All side travel switches for a conveyor are wired in series as a single input t o the control system. E-stops are hardwired into the motor control circuit with a parallel contact input to the control system for monitoring. Each conveyor in a "GROUP" is interlocked to the conveyor preceding it. starting a warning horn is sounded.
Prior to conveyor
Conveyor GP-12 (B55016) and GP-14 (B43036) are variable speed conveyors; however, the
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before the group is started. Where appropriate, a ready status with no critical alarm may be a logical qualification to permit the group to st art. 11.4.10
Equipment Starts/Stops. Operator will start the system from the last conveyor, backwards through to the feed equipment. See Operating Manual for details.
11.4.11 Warning Horn System Prior to the start of any conveyor, or any other machinery such as a screen that can endanger personnel by suddenly starting to move, a warning horn or horns shall sound for a predetermined time. Horns are not necessarily assigned to each individual piece of machinery, but rather to areas of the plant such that the entire area near every piece of machinery, or groups of machinery which may be started together, are covered by the warning sound. Therefore, horns are not driven directly by starter contacts in each drive, but by the Main Automation System. It is the responsibility of the detail engineering designer to lay out the horns and assign them to various devices or groups to insure proper coverage. The Indurating Machine does not have a warning horn before starting. Depending on the mode of starting, the horn logic is as follows: When an individual drive is commanded to start from an image on the HMI, the associated horn (or horns in the case of a long conveyor) shall blow for a period, before the drive ‘run’ command is sent from the Main Automation System to t he MCC. When a group is started from the HMI, all the horns covering the group’s area shall blow for a time, then the components of the group shall sequentially start in their normal order. It is not necessary for each piece in the group to have its own horn blow delay, unless the start sequence is interrupted.
ANNEXURE I- PID LOOP LIST AREA 1 Sl No.
1
Description
Ball Mill #1 Weigh Belt Feeder control
PID Loop Number
Calculation block
Set point from
Feed back from
Final control Element
Status
Area
WIC-B01-0107,
WFC-0108
JIC-0206
WIT-B01-0107
Weigh feeder motor
PKG
01
R-01-1001
4
294.8
Weigh feeder motor
PKG
01
R-01-1001
4
294.8
JIC-0206
JY-0206
Operator
Summation of Power from Drive 1 and drive 2
WIC-B01-0117,
WFC-0118
JIC-0506
WIT-B01-0117
JIC-0506
JY-0506
Operator
Summation of Power from Drive 1 and drive 2
FY-0042
2
Ball Mill #2 Weigh Belt Feeder control
3
Ball Mill 1
FIC-B01-0042
4
Ball Mill 1
FIC-B01-0020
5
HYDROCYCLONE DENSITY MEASSUREMENT
DIC-B01-0036
DY-0036
FY-1040
6
Ball Mill 2
FIC-B01-1040
7
TANK PROCESS WATER FLOW MEASUREMENT
FIC-B01-1020
8
TANK PROCESS WATER FLOW CONTROL VALVE
DIC-B01-1036
DY-1036
EFD Ref
EFD Rev
12.5
12.5
Unit
Control Valve % Opening
Remarks
TPH kWh/Ton TPH kWh/Ton
OPERATOR
FIT-B01-0042
FCV-B01-0044
PKG
01
R-01-1002
4
Package Vendor to Provide
DIC-B01-0036
FIT-B01-0020
FV-0021
PKG
01
R-01-1003
4
Package Vendor to Provide
OPERATOR
DIT-B01-0036
PKG
01
R-01-1003
4
1905
kg/m3
OPERATOR
FT-B01-1040
FCV-B01-1042
PKG
01
R-01-1005
4
Package Vendor to Provide
DIC-B01-1036
FIT-B01-1020
FV-1021
PKG
01
R-01-1006
5
Package Vendor to Provide
OPERATOR
DIT-B01-1036
PKG
01
R-01-1006
5
Package Vendor to Provide
Instrumentation
01
R-01-1019
5
Operator
LV-B01-1801, (upto 25% sp)Motor41104-1 and 2(from 60% sp)
9
Filtrate and Wash Water Tank Radar
10
Outlet of Wet Grinding Cooling Water Strainer
TIC-B01-2101
TT-B01-2101
Cooling Tower fan motor
Instrumentation
01
R-01-1021
11
Wet Grinding Cooling Tower
LIC-B01-2106
LIT-B01-2106
LV-B01-2106
Instrumentation
01
R-01-1021
12
W.G. Seal Water Surge Tank-Flanged
LIC-B01-2306
LIT-B01-2306
LV-B01-2306
Instrumentation
01
R-01-1022
4
13
Thickener overflow sump inlet
LIC-B01-0804
LIT-B01-0804
LV-B01-0804A AND LV-B010804B
14
Cooling water tank 35103
LIC-B01-0901
LIT-B01-0901
LIC-B01-1801
Set Value
LIT-B01-1801
LV-B01-0901
Instrumentation Instrumentation
01 01
R-01-1023 R-01-1028
25000
kg/h
2
34
O
2
10000
kg/h
32.4
FISHER offer considered
18000
kg/h
43.8
FISHER offer considered
4 2
13100 / 10000 1000
50.5
FISHER offer considered
C
kg/h kg/h
22.1 / 19 67.2
FISHER offer considered % Opening to re-check / Fisher offer considered
ANNEXURE I- PID LOOP LIST AREA 2 Sl No.
Description
PID Loop Number
Calculation block
Set point from
Feed back from
Status
Area
1 2
Weight Belt Feeder LSF-11
WIC-B02- 2215
WFC-2215
WFC-2215
WIT-B01-0107
Weigh feeder motor
PKG
01
R-02-1001
4
22.7
TPH
Weight Belt Feeder CF-11
WIC-B02-2216,
WFC-2216
WFC-2216
WIT-B01-0107
Weigh feeder motor
PKG
01
R-02-1001
4
21.2
TPH
Final control Element
EFD Ref
EFD Rev
Set Value
Unit
Control Valve % Opening
Remarks
ANNEXURE I- PID LOOP LIST AREA 3 Sl No.
Description
PID Loop Number
Calculation block
Set point from
Feed back from
Status
Area
1 2
Iron Ore Filter Cake Feeder FCF-11
WIC-B03- 3111
WFC-3111
WIC-0400
WIT-B03-3111
Weigh feeder motor
PKG
03
R-03-1001
5
301.3
TPH
Final control Element
EFD Ref
EFD Rev
Set Value
Unit
Iron Ore Filter Cake Feeder FCF-12
WIC-B02-3121
WFC-3121
WIC-0400
WIT-B03-3121
Weigh feeder motor
PKG
03
R-03-1001
5
301.3
TPH
3
Ground Coal/Limestone Storage Bin Loss-in-Weight Screw Feeder
WIC-B03-3211
WFC-3211
WIC-0400
WE-B03-3211
Weigh feeder motor
PKG
03
R-03-1002
3
16.6
TPH
4
Ground Bentonite Storage Bin Loss-inWeight Screw F eeder
WIC-B03-3311
WFC-3311
WIC-0400
WE-B03-3311
Weigh feeder motor
PKG
03
R-03-1003
3
3.8
TPH
Control Valve % Opening
Remarks
ANNEXURE I- PID LOOP LIST AREA 4 Sl No.
Description
PID Loop Number
1 2 3 4 5 6 7
Conveyor BDF-11F
WIC-B04-0106
Conveyor BDF-11G
WIT-B01-4101
Calculation block
Set point from
Feed back from
Operator
WIT-B04-0106
Operator
WIT-B01-4101
Final control Element Weigh feeder motor Weigh feeder motor
Status
Area
PKG
04
PKG
04
EFD Ref R-04-1001 R-04-1001
EFD Rev 3 3
Set Value 130 130
Unit TPH TPH
Conveyor BDF-11E
WIT-B04-0203
Operator
WIT-B04-0203
Weigh feeder motor
PKG
04
R-04-1002
3
130
TPH
Conveyor BDF-11D
WIT-B01-0020
Operator
WIT-B04-0223
Weigh feeder motor
PKG
04
R-04-1002
3
130
TPH
Conveyor BDF-11C
WIT-B04-0303
Operator
WIT-B04-0303
Weigh feeder motor
PKG
04
R-01-1003
3
130
TPH
Conveyor BDF-11B
WIT-B04-0323
Operator
WIT-B04-0323
Weigh feeder motor
PKG
04
R-04-1003
3
130
TPH
Conveyor BDF-11A
WIT-B04-0403
Operator
WIT-B04-0403
Weigh feeder motor
PKG
04
R-04-1004
4
130
TPH
Control Valve % Opening
Remarks
ANNEXURE I- PID LOOP LIST AREA 7 Sl No.
Description
2
B35008 Machine Discharge Scrubber Sump B35010 Product S creening Scrubber Effluent Sump
3
B35011 Indurating Transfer Sump
1
PID Loop Number
Calculation block
Set point from
Status
Area
EFD Ref
EFD Rev
Set Value
Unit
Control Valve % Opening
Feed back from
Final control Element
LIC-B07-6206
LIT-6206
LV-B07-6206
Instrumentation
07
R-07-1002
3
64000
kg/h
66.2
LIC-B07-2017
LIT-2017
LV-B07-2017
Instrumentation
07
R-07-1004
3
12000
kg/h
55.5
LIC-B07-5363
LIT-5363
LV-B07-5363
Instrumentation
07
R-07-1006
3
21000
kg/h
27.0
Remarks
FISHER offer considered FISHER offer considered Minimum Flow / FISHER offer considered
