Air Heaters

Tanj njun ung g Ja J ati B Tr Tr ain inii ng AIR A IR HEATERS HEA TERS

OPERATIONS AIR A IR HEATERS HEA TERS

Tanjung Jati B Training

P.T. Cen t r al J av a Po w er Tanju njung ng Ja J ati B Units 1 & 2

2 x 660M 660MW W (n (n et) et )

B o i l er

Pr ec i p i t at o r

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Tri-Sector Air Heater Function

Two (2) 50% capacity Ljungstrom Tri-Sector Air Heaters transfer heat from the flue gas leaving the boiler to the incoming cold primary and secondary air.


Secondary Air System

FD Fan

Tri-Sector Air Heater

SCAH

Tri-Sector Air Heater

N SCAH

FD Fan


Tri-Sector Air Heater Sections The Air Heater is divided into three (3) sections… Flue Gas Side Secondary Air Side (~4/5 of air side) Primary Air Side (~1/5 of air side)


Tri-Sector Air Heater Orientation ROTATION

ROTATION

GAS SIDE

GAS SIDE

SECONDARY AIR SIDE

AIR HEATER “ A”

SECONDARY AIR SIDE

PRIMARY AIR SIDE

AIR HEATER “ B”


Tri-Sector Air Heater Air Heater Components Terms to remember… Rotor & Rotor Drive Emergency Air (Rotor) Drive Heating Elements or Baskets Guide & Support Bearings Oil Circulating Systems Sector Plates & Seals Thermocouple Temperature Monitoring Panel Sootblower Water Washing


Tri-Sector Air Heater Flow Paths SECONDARY AIR OUT PRIMARY AIR OUT FLUE GAS IN


Tri-Sector Air Heater Heating Elements (Baskets) “ Baskets” , which contain a multitude of corrugated steel plate, absorb the heat from the flue gas stream.

HOT END LAYER (42”)

COLD END LAYER (10” )

HOT INTERMEDIATE LAYER (12”)


Tri-Sector Air Heater Heating Elements (Baskets)

CORRUGATED PLATE DESIGN


Tri-Sector Air Heater Rotor Drive

The Air Heater Rotor Drive consists of the following major components… 30 HP, 380 VAC Motor Speed Reducer Fluid Coupling Pinion Gear & Hub


Tri-Sector Air Heater Rotor Drive

43.5 LITER


Tri-Sector Air Heater Emergency Air (Rotor) Drive If the electric motor should lose power, an Emergency Air Drive is used to insure the continuous operation of the Air Heater.


Tri-Sector Air Heater Emergency Air (Rotor) Drive

SOLENOID VALVE FAILS OPEN UPON LOSS OF POWER


Tri-Sector Air Heater Bearings

The Air Heater has two (2) main bearings, one Guide Bearing & one Support Gearing. The Guide Bearing is located at the top portion of the rotor assembly, while the Support Bearing is near the bottom.


Tri-Sector Air Heater Bearings GUIDE BEARING

SUPPORT BEARING


Tri-Sector Air Heater Guide Bearing Due to the Guide Bearing being located in a hot environment, an Integral Oil Circulating System is provided to maintain oil viscosit y and provide a bath of clean oil. Cooling water is from the CCCW System.


Tri-Sector Air Heater Integral Oil Circulating System (Guide Bearing) The Integral Oil Circulating System has the following components… Oil Pump Dual Oil Filters Oil Pressure Gauge Differential Pressure Gauge with Switch Oil-Water Heat Exchanger Pressure Relief Valve (set @ 75 psig) Thermometer Probe Adjustable Temperature Controller (set @ 38o C)


Tri-Sector Air Heater Integral Oil Circulating System (Guide Bearing)


Tri-Sector Air Heater Integral Oil Circulating System (Guide Bearing)

OIL REQUIREMENT: ~43.5 LITERS


Tri-Sector Air Heater Integral Oil Circulating System (FIRE Potential)

Due to the potential for oil to leak and get under the casing and insulation, there is always a potential for fires to start. It is recommended that an operator periodically check the oil system.


Tri-Sector Air Heater Support Bearing The Support Bearing is equipped with an Oil Circulation System. The bearing itself is submerged in an oil bath requiring approximately 185.5 liters.


Tri-Sector Air Heater External Oil Circulation System (Support Bearing) Unlike the Integral Oil Circulating System for the Guide Bearing, the Support Bearing has what is called an “ External Oil Circulating System” . This system is similar but has no Oil-Water Heat Exchanger.


Tri-Sector Air Heater External Oil Circulation System (Support Bearing) The External Oil Circulating System has the following components… Oil Pump “ Micro-Klean” Filter Pressure Gauge Thermometer Pressure Relief Valve (set @ 50 psig) Filter Differential Pressure Switch


Tri-Sector Air Heater External Oil Circulation System (Support Bearing)


Tri-Sector Air Heater Sector Plates & Seals

The sealing systems are comprised of the follow seals… Radial Circumferential Axial Rotor


Tri-Sector Air Heater Sector Plates & Seals

Our discussion will focus on the Radial Seals. The hot and cold sides of the air heater have these seals which run from the “ center” of the air heater to its outer circumference. Radial Seals, along with Sector Plates minimize Air Heater Leakage…


Tri-Sector Air Heater Sector Plates & Radial Seals

RADIAL SEALS (HOT END)


Tri-Sector Air Heater Sector Plates & Radial Seals (Leakage)

…Leakage occurs between the following Air and Gas streams… Primary Air stream to the Flue Gas stream Primary Air stream to the Secondary Air stream Secondary Air stream to the Flue Gas stream


Tri-Sector Air Heater Leakage Leakage occurs because the pressure on the air side is greater than the pressure on the gas side. Also, Primary Air pressure is greater than Secondary Air Pressure. Flue Gas In

Flue Gas Out

Pri. Air Sec. Air Out Out

Pri. Air Sec Air In In



Sector Plates are also located on both the Hot and Cold End of the Air Heater. The Sector Plates are essentially “ pie-shaped” plates and are adjustable on the Hot Side and stationary on the cold side. Sector Plates are used to set the gap between the Plate and the Radial Seals.



1 of 3 SECTOR PLATES

RADIAL SEAL


Tri-Sector Air Heater Sector Plates - Numbering

GAS SIDE

1

2

PRIMARY AIR SIDE

SECONDARY AIR SIDE

3

Top View of Air Heater “ B” (Mirror Image for Ai r Heater “ A” )



The Hot Side Sector Plates, which are adjustable, incorporate an automatic system which checks and sets the gap between the plate and the Radial Seals. A Rotor Position Sensor is utilized for this task. The Rotor Position Sensor Assembly and Sector Plate Drive Assembly are located at the ends of the Sector Plate.



The Sector Plate position can also be set manually. Each Sector Plate, numbered “ 1” , “ 2” & “ 3” , has its own Local Control Panel to perform this function. CAUTION! An experienced operator or technician should be the only one to adjust the Sector Plates via the Local Panel, otherwise Radial Seal damage can occur.


Tri-Sector Air Heater Sector Plates – Drive Location ROTATION

ROTATION

GAS SIDE

GAS SIDE

2

1 SECONDARY AIR SIDE

1

3

AIR HEATER “ A”

2

3

PRIMARY AIR SIDE

SECONDARY AIR SIDE

AIR HEATER “ B”


Tri-Sector Air Heater Sector Plate Local Panel


Tri-Sector Air Heater Thermocouple Temperature Monitoring Device

The Thermocouple Temperature Monitoring Device (TTMD), is designed to measure the air temperature leaving the Air Heater. The TTMD will alarm if a thermocouple detects an unexpectedly high local air outlet temperature. A high outlet air temperature could be an indication of a FIRE internal to the Air Heater. Each Air Heater has one TTMD Panel.



The TTMD utilizes the following Thermocouples… One (1) for Air Inlet Temperature One (1) for Gas Inlet Temperature Fourteen (14) for Air Outlet Temperature



The 14 Thermocouples are located internally along the radius of the rotor with a spacing of approximately one foot (305 mm) and as close as possible to the heat transfer surface (baskets). All Thermocouple readings are routed to the TTMD Panel for “ evaluation” or “ comparison” . The TTMD panel will send an alarm signal to the DCS and alarm locally as well.



CUTAWAY OF ROTOR SECTION

# 1 4 u r h 1 t # T / C THERMOCOUPLES LOCATED IN THE AIR OUTL ET STREAM


Tri-Sector Air Heater TTMD Panel Alarm – Potential Fire

When the TTMD Panel has a High Temperature Alarm, immediate attention should be given to it by an operator and I&C technician. First, push the alarm acknowledge button and see if the alarm clears or resets. If not, check to see if the Thermocouple is functioning properly, for example, the thermocouple has not failed (infinite resistance).



At first evidence of a fire from temperature indication or otherwise, inspection of the Air Heater should be made. If the temperature continues to rise or if a fire is visible, the fans should be shut down and water should be admitted to the Air Heater in sufficient quantities to quench the fire.



If it is possible to isolate the area of the fire, then stop the Air Heater so that the water can be directed at the fire. On the other hand, if the fire is burning in several areas, continue to rotate the Rotor as long as it will turn. Note: If the fire has progressed to the metal Heating Elements, temperatures could range from 1093o C to 2204o C.



DO NOT CONSERVE ON WATER!! GET AS MUCH WATER AS POSSIBLE ON THE FIRE!!


Tri-Sector Air Heater Out of Service Water Washing

Over time, Air Heater air and gas pressure differential may increase. Air heater inspection and water washing may be necessary. A Water Wash system with wash nozzles is provided to serve this task.


Tri-Sector Air Heater Out of Service Water Washing (Pressure Drop)

Flue Gas In

Pri. Air Sec. Air Out Out

Pressur e Difference Acr oss Element s Pin - Pou t

Pressure Difference Acr oss Element s Pin - Pou t

Flue Gas Out

Pri. Air Sec Air In In


Tri-Sector Air Heater Sootblower

The extendable lance sootblower is used to minimize the buildup of combustion byproducts on the Air Heater’s heat transfer elements. It also minimizes No. 2 fuel and fuel ash deposition during relatively cold start-up conditions.


Tr i -Sec t o r A i r Heat er Typical Sootblow ootblowe er Arrange Arrangeme ment nt


Tr i -Sec t o r A i r Heat er Plu lugg gged ed Hea Heati ting ng Elements


Tr i -Sec t o r A i r Heat er Sootblower

Sinc ince e there is no n o auxi auxili lia ary boil b oile er, and and if i f both bo th unit u nits s are “ cold” cold ” , com compresse pressed d air is used. Servi rvice ce Air Compressors provid pr ovide e this air. Stea team m whic w hich h is i s ge g ene nerally rally more m ore econ economi omica cal, l, should shou ld be used when aux auxil iliary iary stea s team m is i s avail availa abl ble e.


Tri-Sector Air Heater Sootblower

During boiler start-up, the Air Heater Sootblower should be operated on a continuous basis. This is due to the greater potential for the accumulation of No. 2 Oil combustion byproducts and oil itself. Once the Boiler is up and operating, the sootblower is used periodically (typically once per shift).


Tri-Sector Air Heater Start-Up & Shutdown

The Air Heater is started prior to firing the Boiler and the sootblower is operated on a continuous basis. During normal operation, periodically check the operation of the Air Heater and be sure the Emergency Air Drive air isolation valve is open.


Tri-Sector Air Heater Start-Up & Shutdown

During normal operation, check for unusual noises. A periodic or repetitive noise can be a sign of excessive rubbing between the Radial Seals and the Sector Plate(s). When shutting down the Boiler, the sootblower should be operated continuously prior to extinguishing the fires.


Tri-Sector Air Heater Loss of Air Heater during Unit Operation

Most often, the reason for an Air Heater to stop during Unit Operation is due to electrical overload of the Main Drive Motor. This is generally due to excessive rubbing between the Radial Seals and the Hot End Sector Plates.



If this should occur, the Emergency Air Motor Drive will not be able to rotate the Air Heater as well. Provisions should be made to reduce Unit Load as quickly as possible so that the Air Heater can be isolated from the incoming Flue Gas, if this should become necessary.



At the time of Air Heater Rotor Stoppage, the Operator should immediately go to the Air Heater and Retract all three (3) Sector Plates by way of the Local Control Panel. Once this is done, try to restart the Air Heater Drive Motor.



If the Main Drive Motor is successfully restarted, continue to operate the Air Heater with the Sector Plates in the retracted position. Once the Unit is stable at the reduced Unit Load, the Sector Plates can be extended by automatic control.



If the Main Drive Motor will not restart, and when Unit Load permits, close all Isolation Dampers to isolate the Air Heater. The main reason for retracting the Sector Plates as soon as possible is to avoid damage of the Radial Seals.



All Operators should thoroughly familiar with the Air Heater operating instructions found in the Operations & Maintenance Manual.


Tri-Sector Air Heater Performance

•

High Leakage Increases fan power requirements Possible load curtailment Reduced thermal performance Negative effects on p recipitators and scrubbers

•

High Pressure Drop Increases fan power requirements

•

Low Thermal Performance High gas outlet temperature Low air outl et temperature Lowers unit efficiency Increases leakage


Tri-Sector Air Heater Performance Build up and blo ckage of heating surface flow paths by ash and corrosion products Effects Increases pressur e drop Increases leakage Reduces thermal performance and effects b oiler operation Shortens element lif e Limits u nit capacity

Control Sootblowing Water washing Cold end temperature contro l


Tri-Sector Air Heater Performance

Surface Plugging Ineffective s ootblowing Low cold end metal temperature Incomplete water washing Ash carryover

High Leakage Deteriorated seals Incorrect seal adjustment Improper operations Rotor or sector plate problems


Air Heaters

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