ASH HANDLING PLANT
INTRODUCTION TO ASH HANDLING PLANT: Large quantity of ash is generated in coal based thermal power stations. This huge quantity quantity of ash, considere considered d an environm environmental ental pollutant, pollutant, requires huge quantities of water and large tracts of land for its safe disposal disposal in the conventional conventional ash handling handling systems. systems. This huge quantity quantity of thermal plant waste i.e. ash is fast becoming a useful resource / materi material al needin needing g produc products ts qualit quality y of variou various s requir required ed standa standards rds for different applications. This emerging emerging utilization utilization potential potential of ash now calls for promoting promoting technological advancements in ash collection and storage systems with in built built facili facilitie ties s for bulk bulk utiliz utilizatio ation n applic applicatio ations ns as well well as meeti meeting ng stricter environmental norms. Keeping in line with the above requirements the dry ash handling system as NCPS / Dadri has been designed and provided with in built facilities to facilitate bulk utilization of ash besides conserving land and requiring less water for ash disposal purpose.
45
ASH HANDLING PLANT
Overview of NTPC Dadri (Thermal Plant) : •
STATION CAPACITY
: 840 MW
•
COAL CONSUMPTION
: 3.66 Million T / Year
•
ASH GENERATION
: 1.5 Million T / Year
•
ASH DISPOSAL
: Dry Ash System
•
•
•
DRY ASH SYSTEM Transportat Transportation ion
: Vac. Extraction & Pr.
WATER REQMT. FOR ASH CONDITIONING
: 20 % by Weight
ASH MOUND AREA
: 375 acre
Flue Gases & Fine Ash Coal Consumption /Day/Unit= Ash 3000T Generation /Day/Unit( 34% ) = 1000T (Approx.)
Bottom Ash Hopper
Economis er
ES P
CAT
BA + CA =20% of Total Ash System (200 T Slurry /Day /Unit)
APH
APH + ESP =80% of Total Ash Dry System (800 T /Day /Unit)
46
ASH HANDLING PLANT
CHEMICAL COMPOSITION OF FLY ASH: •
Silica, SiO2
: 64.57 %
•
Alumina, Al2O3
: 24.08%
•
Ferric Oxide, Fe2O3
: 6.4%
•
CaO
: 0.84-2%
•
MgO
: 0.84%
•
P2O5
: 0.15%
•
SO3
: 0.05%
•
Na2O
: 0.36%
•
Potassium Oxide
: 0.55%
•
Carbon, C
: 0.5 %
•
pH
: 8.10
•
Bulk Density
: 0.81 gm/ml
47
ASH HANDLING PLANT
DRY ASH HANDLING ADVANTAGES:
SYSTEM
AND
ITS
The con cept of dry ash handling has been utilized for th e first t im e i n I nd ia a t a N TP C D ad ri . C on ve nt io na l a sh h an dl in g s y st em , r eq u ir es e no rm ou s l a nd w at er a n d h a s a s so ci a te d p rob lems of l ea ch in g ef fe ct , d us t b lo w et c. S ome ma jo r aspects with respect to dry ash handling system that make it more favorable in comparison to conventional method of wet disposal are:
1.
LESS REQUIREMENT OF LAND: Approx. land required for ash mound area is 0.8 acres per MW of generation capacity for 30-35 years. At NTPC Dadri, total 375 acre land is acquired for ash mound which is designed for 25 years ash output of four 210 MW units i.e. only 0.45 acre land per MW of generation capacity for 25 years is required in dry ash handling system.
2.
LESS WATER REQUIREMENT: In conventional method i.e. lean slurry disposal system of ash, is ash is mixed with water in approx. 1 : 10 ratio and the slurry formed is transported through the pipelines to remote ash bund area by means of ash slurry disposal pumps. At NTPC Dadri, dry ash is handled and water required for this system is only for providing the moisture to ash to control the fugitive dust during process. Approximate ash water ratio in this system is 10 : 1.
3.
ELIMINATES UNDERGROUND WATER AND SURROUNDING WATER WAYS POLLUTION: At NTPC Dadri, before putting PFA, minimum 1.00 meter thick drainage blanket is laid over the ground with FBA. This layer allows water to flow freely to the perimeter ditch and protects the ground water from toxic leach ate contamination.
4.
FACILITATE LARGE SCALE UTILIZATION OF ASH.
5.
PROGRESSIVE RESTORATION OF ASH DISPOSAL SITE AS USEFUL LAND.
48
ASH HANDLING PLANT
SALIENT FEATURES OF INSTALLED SYSTEM: •
•
•
•
•
Extraction & transportation of fly ash in complete dry form. System having provision to store selected grade of ash in separate Silo (Silo-3). Complete re-circulation of water for Bottom Ash Handling System. Unloading & Transportation of conditioned ash from Silo’s & decanted bottom ash from Hydrobins on to belt conveyor’s. Construction of Ash Mound in a systematic manner.
49
ASH HANDLING PLANT
GENERAL DESCRIPTION OF ASH HANDLING HANDLING PLANT PLANT SYSTEM: The Ash Handling System at Dadri, Stage-1, is the removal of ash from 4x210 MW plant and their associated economizers, air pre-heaters and electrostatic precipitators to the ash mount area.
FURNACE BOTTOM ASH (FBA): Bottom ash, resulted from the combustion of coal, is continuously collected in water impounded bottom ash hopper and periodically transferred to the hydrobin by means of jet pumps and associated pipe lines. From hydrobin, the settled ash is transported by conveyors to the ash mound area. The decanted water from hydrobin is transferred to setting tank / surge tank for re-circulation. Hydrobin is decanted through a floating decanter and 10 stationary decanter columns. Each bin discharges de-watered ash onto its dedicated reversing belt conveyor. In one direction the ash is transported to ash mound through series of belt conveyors and in other direction ash can be loaded into lorries for various ash utilization purposes.
Bottom Ash / Coarse Ash Removal System Economiser Hoppers HBN-1
LP Water
Flushing Apparatus HBN-2
HP Water
CAT LP Water
OFT
HBN-3
Bottom Ash hopper BAH Gates
OFP-1 & 2
CG
CG
HP Water
50
ASH HANDLING PLANT
The coarse ash from economizer hoppers is also transferred to the hydrobin, via, flushing apparatus, coarse ash tank and pipe lines, for its further removal to the ash mound area. Alternative the de-watered hydrobin ash can also be unloaded to trucks through the reversible belt conveyor.
PULVERIZED FLY ASH (PFA): Fly ash from air pre-heater collection chutes and electrostatic precipitator’s collection chutes is continuously removed to the buffer hoppers located near the ESP, by means of vacuum pumps. For buffer hoppers, dry ash is pneumatically conveyed, via pipe lines to the storage silos for its further removal to the ash mound area by means of belt conveyors. Alternate arrangement is provided to load the unconditioned dry ash from silo to closed trucks. Altogether five silos are provided for all the four units. Out of five silos one silo is common which receives fly ash from both the transport lines of all the four units and remaining each silo receives fly ash from both the transport lines of only two units. Thus fly ash from unit-1 can be transferred to silo-1, silo-2 and common silo. Segregating valves in each pressure transport line. Located at the fly ash storage silo, controls which of the three silos, the fly ash is to be deposited. Provision is also made in the system to collect separately the saleable and non saleable ash. When the fly ash reaches the silo it enters a target box and falls by gravity into the silo, while the conveying air passes through a vent filter mounted on the silo roof and is discharge to the atmosphere. A pressure relief door is mounted on the top of the silo to relieve any excess pressure from the silo. The vent filter, installed on the top of the silo, is continuously cleaned during system operation. Pulsating air is supplied to clean the fly ash from the exterior surface of the filter bags. The fly ash falls from the bag filter down into the silo. Each silo is provided with three hydromix dust conditioners, two operating and one standby, for the removal and conditioning of fly ash in a moist state. The conditioned fly ash is discharged to a running belt conveyor (to be supplied by others) located below the hydromix dust conditioners. Hydromix dust conditioner is supplied with fluidizing feeder and metering cut off gate. Water is sprayed through nozzles on the fly ash inside the hydromixer to condition the ash. Air slides. Arranged fan rows around the outlet adopter opening in the silo floor, aerate the dust in the silo and functions continuously irrespective of whether silo is used as storage of being loaded/unloaded. Apart from hydromix dust conditioners, each silo is provided with three more outlets for removal of fly ash as an alternative arrangement. Each
51
ASH HANDLING PLANT
outlet is having one manual isolation valve, one solenoid operated plate valve, one rotary feeder and one telescopic chute. Ash is unloaded through feeder in dry form on to a closed truck. The unloading of silo through rotary feeder is controlled only from local control station, whereas unloading of silo through hydromix dust conditioner can be controlled either from local control station or from conveyor control panel. Each silo having the capacity of 2500 MT where as hydrobin capacity is 650 MT.
52
ASH HANDLING PLANT
DETAILED PROCESS OF ASH DISPOSAL SYSTEM: The As h Handling Pl ant comp rises of two ma jor sub- sys tems : 1.
F ro m E SP /A PH /AP H h op pe rs t o S il os t hr ou gh D ry A sh Handling System & Bottom Ash Hoppers/Economizer H op pe r s t o H yd ro bi ns t hr ou gh W et A sh H an dl in g System. DRY ASH HANDLING SYSTEM: The Dry As h is ev acu ated from 24 ESP & 4 AP H h op per s a nd is tr an sp orted to a sh s tora ge Si los continuously in two stages. •
First from ESP & APH hoppers to Buffer Hoppers through Vacuum System. There are four buffer hoppers & four Vacuum Pumps in each Unit. One set of Buffer Hopper & Vacuum Pump collects ash from 12 ESP & 2 APH hoppers. Thus two in service & two stand-by. E ac h B uf f er H op pe r i s c on n ec t ed w it h a n i n di vi d ua l V ac uu m P ump o f 5 0 m 3 / m i n c a p a c i t y a t 1 6 i n c h H g Vacuum. Bag Filters (81 nos. per Buffer Hoppers) inbuilt in the Buffer Hopper separate ash from ash-air mixture & ash is being collected in the Buffer Hopper. •
[Vacuum switches installed in the vacuum line transmit s i gn a ls t o t h e p r og ra mma b le c on t ro l le r. T h e v a ry in g line vacuum is used to control system operation. The material handling valves operate sequentially through the hopper rows. It opens initially after establishing a system operating vacuum and cycles close and open between the full load and no load set point. When the h op per i s e mp ty t he v ac uu m w il l f al l t o t he l ow s et p oi nt a nd t he ma te ri al h an dl in g v al ve c lo se s. T hi s results in increase of line vacuum. When the vacuum r ea c he s t h e s y st em v a cu u m s et p oi n t, t h e s y st em i s signaled to advance to the next hopper in sequence.] S ec on d ly f r om B uf f er H op pe r t o A sh s t or a ge Silos through pressure system. There are two sets of Transport Air Com pres sor (15 0 m 3 /min at 2.29 kg /cm 2 each) & Transport Air Line (1 km each) in each Unit. Each set is connected with two sets of Buffer Hopper. Thus one set runn ing & ot her stand-by. •
[Fly ash enters the transfer hopper (buffer hopper) and is directed downward by means of a stone box a rr an ge me nt . T he t ra ns fe r h op pe r i s p ro vi de d w it h 53
ASH HANDLING PLANT
a er at io n a ir t o a ss is t i n m ai nt ai ni ng t he f ly a sh i n fluidized condition. The bag filters, installed on the top o f t h e b u ff e r h op p er , i s c on t in u ou s ly c le an ed d u ri n g system operation through solenoid operated pulsating air system. Two air lock tanks are installed below each transfer hopper.Each air lock tank has an inlet or top gate and outlet or bottom gate to control fly ash flow f r om t ra n s h op p er t o s i lo . A er a ti on a b ov e e ac h g a te assist to maintain the fly ash in fluidized condition. An e qu a li ze r v al ve c on t ro l s t h e p re ss u re i n t he a i r l oc k chamber. When top gate is open, the equalizer valve is c on nect ed wi th t he tr an sf er h op per t o en su re t he pressure in the air lock tank is equal to the transfer hopper. When the top gate closes, the equalizer valve s hi ft s p os it io n, a ll ow in g a ir f ro m t he t ra ns po rt a ir compressor to pressurize the air lock tank and assist the flow of fly ash when bottom gate opens.] The plant has 5 fly ash storage Silo’s (300 0 m 3 each) for four units. The Silo’s 1-2-3 for Units # 1 & 2 and Silos 3-4-5 for Units # 3 & 4. Silo 3 is common for all the four Units for saleable purpose. The system has p ro vi s io n f o r s t or a ge o f s eg r eg a te d f i ne f l y a s h f r om ESP hoppers to Silo-3. •
E a ch S i lo h a s t hr ee H yd r o M ix D us t C on d it i on er s (200 T /hr each) & three Rotary Feeders. In HMDCs Fly As h i s b ei ng cond it ion ed (As h : Air :: 80 : 20 ) & u nl oa de d i n c on ve yo r b el t a nd s en t t o A sh M ou nd . Throu gh Rotary Fee der s dry ash is unloaded in cl osed truck. •
BOTTOM ASH HANDLING SYSTEM: The Bot tom Ash imp ounded into Bottom As h Hop per (194 m 3) and fed into Clinker Grinder through Bottom Ash Hopper discharge Gate. After Clinker Grinder the sl urry li ne i s eva cu ated by Hydr o ej ector ( inl et Pressure 20 kg /cm 2 & outlet Pressure 4 kg /cm 2) a n d sent to Hydrobin (650 cu. M) through Slurry Line (1 km long). •
Each Unit has four Clinker Grinders including Gate Housing and two slurry lines, operated simultaneously. The plant has six Hyd robins for four Un its. Three nos. for a group of two Units. •
54
ASH HANDLING PLANT
The coarse ash from ec on omi zer is flashed by LP wa ter a nd col lect ed in Coa rs e As h T ank . Fur th er evacuated through hydro ejector & and sent to Hydrobin through Slurry Line. •
Bottom Ash Hopper evacuation done once in shift. N or ma l e va c ua t io n t i me b y t wo h yd r o e je ct or s i s 4 5 minutes. Evacuation of Coarse Ash Tank once in a shift by 20 minutes through one hydro ejector. In Hydrobin ash is being separated & collected and water overflows t o S et tl in g T an k ( 75 0 m 3) , a nd f ur th er o ve rf lo ws t o Surge Tank (1500 m 3). All the HP & LP pumps are taking suction from Surge Tank. •
L P w at er p ump s ( ea ch 2 94 m 3 /hr a t 6 k g / cm 2) feeding water for Bottom Ash Hopper filling/over flow, Economizer flashing to Coarse Ash Tank, Seal Trough m ak e u p . A ll t he t hr ee w at er o ve rf l ow s t o O ve r F l ow Tank (24 m 3). From Over Flow Tank the water is being recycled to Settling Tank through Over Flow Pump (200 m 3 /hr) and Over Flow discharge line. •
Initially Hydrobin is filled with water. And afterwards ash settles down & water overflows to the Settling Tank. Gradually Ash level rises in the Hydrobin. Normally after six Bottom Ash Hopper deashing around 400 T of ash accumulated in the Hydrobin. Then the H yd ro bi n t ak en u nd er d ec an ta ti on . Wa te r d ra in ed through decanter plates to settling tank. It takes 8 to 1 0 h ou r s & t h en u n lo ad ed t o c on v ey or b el ts t h ro ug h Vibrofeeder and send to Ash Mound. •
2.
T ra ns po rt at io n o f c on di ti on ed A sh f ro m S il os & Decanted Bottom Ash from Hydrobins to Ash Mound T hr ou gh C on ve yo r b el ts a nd c on st ru ct io n o f A sh Mound in a systematic manner. Fly Ash collected in Silos & Bottom Ash decanted in Hydrobins transported to Ash Mound area by a series of belt conveyors system and ash is dumped in a systematic manner. •
Ash can be damped in three different areas in ash mound area depending upon the system availability and weather condition. •
Normally ash is damped in permanent ash mound area through Spreader-I & II. •
55
ASH HANDLING PLANT
SILO UNLOADING SYSTEM FROM 1ST UNIT Silo Vent Fan
BAG FILTERS
FROM 2ND UNIT BAG FILTERS
TARGET BOXES
Silo Vent Fan
.
Ash Storage Silo: Capacity 2949 m 3 each
6 deg
ROTARY FEEDER HEATER
ELESCOPIC CHUTE VENT FAN
TELESCOPIC CHUTE
DRY ASH INTO CLOSED TANKERS
SAB-2
CONDITIONED ASH INTO OPEN TRUCKS
SAB-1
HMDC
ASH MOUND
During rainy season or system non-availability, ash i s b ei ng d ump ed i n T emp or ar y S to ck Y ar d t hr ou gh Stacker from where it is reclaimed to the permanent Ash Mound through Reclaimer. •
In case of non-availability of permanent as well as temporary stock yard, ash is being dumped in Emergency Stock Pile from where it is reclaimed with the help of mobile equipments like dumpers & dozers. •
56
ASH HANDLING PLANT
THE ASH MOUND: Out of 500 acres of land for the dry ash disposal system, ash mound will spread over an area of 375 acres which will go up to a height of 55 meters with top most flat area of 140 acres. The maximum side slope of ash mound will be 1:4 it will hold 53 million cubic meters of ash. Ash mound system is designed for 25 years ash output of four 210 MW units & one 500 MW unit. The mound design covers stability, erosion and considerations of noise dust and waterborne pollution.
environmental
EXISTING OPERATIONAL PRACTICES TO UNLOAD DRY ASH FROM SILO TO ASH MOUND: •
First of all path is selected to unload fly ash / bottom ash.
•
Conveyors are selected on control desk by selector switches.
•
Selected conveyors are made healthy electrically from their modules.
•
•
•
•
•
•
•
•
•
•
Operated belt sway, pull cord etc. Protection device switches are normalized. All the flap gates are positioned on selected conveyors manually or electrically at various junction houses (JH's). Individual location operator gives the clearance through p.a. system before start the conveyor belt. For HMDC's operation - conveyor belt, M.S. water pump and silo aeration blower, Instrument air compressor should be in running condition. System is started in backward sequence from machine SP-1 / SP-2 / Stacker / SC-2 as per selection of ash unloading area. Than C-33, C32, CD/CC, CA/CB, C-30/31, C-24/25, C-22/23, C-20/21 and Silo Conveyor C-01 to C-05 or Hydrobin Conveyor C-10 to C-15 are selected and started from ash mound control room. Machine conveyors are started from its local control panel. Conveyor belt system is used to unload dry / bottom ash from silo and hydrobins. System is designed to run in two shifts. Generally silo unloading is done in 1st Shift and hydrobin in 2nd Shift or as per requirement / availability of system. Average ash unloading is done 4000 T /day. System runs 7 - 8 hours per day to evacuate this quantity of ash. Belt loading capacity is 2000 T /hr.
57
ASH HANDLING PLANT
•
•
•
•
Each silo pressure is depending on per day coal consumption. Each silo takes different time to become empty. Silos are evacuated upto empty limit daily. system runs more hours.
Due to this practice
Utility factor of this system is 32 and system running hours is 210 220 hours per month. On completion of silo / hydrobin unloading system is stopped from silo / hydrobin Conveyors and then other conveyors are also stopped in forward sequence.
ASH CAN BE DUMPED AT THREE DIFFERENT AREAS IN ASH MOUND DEPENDING UPON SYSTEM AVAILABILITY AVAILABILITY & WEATHER CONDITIONS: Normally ash is taken into permanent ash mound area with the help of boom spreader machine which receives ash from a tripper car lane the final shiftable field conveyor and deposits the ash to 15 meters height up to 60 meters from the center line of shiftable conveyor. a)
During rainy season or system non-availability (like during horizontal shifting of field conveyor), ash is dumped in "temporary stock yard area" from where ash is transferred to permanent ash mound area through re-claimer machines.
b)
In case of non-availability of systems for permanent & temporary ash mound area, ash can be transported to emergency stockpile from where it is reclaimed with the help of mobile equipment. c)
The extendable shiftable conveyors give maximum flexibility for ash mound construction to the full height over the entire area. Short, intermediate modules on pontoons are added or removed to change length. Head and tail units mounted on skids can be either towed by bulldozer sideways or lifted with a big crane to change the position of the conveyor. Modular section of belt conveyor structures of shiftable field conveyor are mounted on pontoons which can be easily towed by bulldozers sideways with the help of special shifting attachments during horizontal shifting of conveyor. Shifting attachment mounted bulldozers facilitate the shifting of conveyor in assembled condition to a new location.
58
ASH HANDLING PLANT
EQUIPMENTS OF AHP: Equipments
Transport Air Compressor Vacuum Pump Buffer Hopper Transport Air Line(300/350NB) Silo(2949m 3) Silo Aeration Blower Silo Vent Fan Hydro Mix Dust Conditioner Instrument Air Compressor Bottom Ash Hopper (194cuM) Coarse Ash Tank Clinker Grinder Hydro Ejector Over Flow Tank Over Flow Pump
Motor rating In kW 545 75 N/A N/A N/A 30 18.5 7.5 125 N/A
N/A 7.5
45
Hydrobin Settling Tank Surge Tank Sludge Pump HP Pumps
11 320
LP Pumps
75
MS Pumps
75
Seal Water Pump
45
Capacity
Pressure In kg/cm 2
Populatio n
159/147 m 3 /min 46.5 m 3 /min 28 T up to high level 55 T max. (40T avg.) 2500 T 12 m 3 /min 200 m 3 /min 200 T/hr
2.29
2*4
-400 mmHg
4*4 4* 4
0.5 - 1.5 atm
2* 4
0.7+0.7=1. 4 atm
5 2*2*5
N/A
2*5 3*5
14 m 3 /min 128 T
7 kg/cm 2
3
N/A
1*4
38 m 3
N/A
70 T/hr
Inlet Pr. 20 Outlet Pr. 4
1*4 4*4 6* 4
54 m 3 245 m 3 /hr 650 m 3 750 m 3 1500 m 3 40 400 m 3 /hr 296 m 3 /hr 296 m 3 /hr 30
2.8
1*4 2*4
3.5 20
6 2 2 2*4 6
7
6
10
3
21.6
2
59
ASH HANDLING PLANT
TECHNICAL DATA OF AHP EQUIPMENT: TRANSPORT AIR COMPRESSOR: Number
:
8 no, 2 for each units
Make
:
Khosla-Crepelle, New Delhi-55
Discharge
:
2.26 kg /cm2 (For Unit# 1 & 2)
Pressure
:
1.97 kg /cm2 (For Unit# 3 & 4)
Flow
:
159 N m3 /min (For Unit# 1 & 2)
Gear Box
:
147 N m3 /min (For Unit# 3 & 4)
Make
:
David Brown Greeves Ltd., Chinchwad, Pune.
Ratio
:
2.49 : 1
Motor
:
545 kW/ 6.6 kV
VACUUM PUMPS: Number
:
16 no, 4 for each unit (2 working, 2 standby)
Make
:
Roots Division Dressers Industries Inc, USA
Type
:
Rotary Lobe Vacuum Blower
Inlet Volume
:
46.8 m3 /min at 16 mm of Hg
Rpm
:
1057
Motor
:
75 kW
/ 415 V
BUFFER BUFFER HOPPER: Number
:
16 no, 4 for each unit (2 working, 2 standby)
Capacity
:
35 m3 up to high level
Volume of air lock tank
:
1.41 m3 (2 no below each Buffer Hopper)
Number
:
81 in each Buffer Hopper
Material
:
Nomex
Size
:
150 mm Diameter & 2750 mm long (each)
BAG FILTERS:
DRY ASH SILO: Number
:
5 no, 1-2-3 for unit 1&2 and 3-4-5 for unit 3&4 Silo no 3 for saleable purpose.
60
ASH HANDLING PLANT
Capacity
:
2949 m3
Diameter
:
15 m
SILO AERATION BLOWER: Number
:
12 no, Set of 2 blowers in series per silo (5 sets working, 1 set standby for all the
Make
:
Swam Engineering
Type
:
Twin Lobe Compressors
:
770 m3 /hr
silos)
Capacity Rpm
Stage-I : Stage-II :
1650 1250
Pressure Stage-I : Stage-II :
7000 Mmwc 14100 Mmwc
Motor
30 kW
:
/ 415 V
These blowers supply aeration air to silo by which dry ash slides towards inlet gate of Hydro Mix Dust Conditioners (HMDC).
SILO VENT FAN: Number
:
10 no, 2no per silo, (1 working, 1 standby)
Make
:
Batliboi & Co. Ltd.
Type
:
Centrifugal
Flow Rate
:
12000 m3 /hr
Motor
:
18.5 kW / 415 V
ROTARY FEEDERS: Number
:
15 no, 3 for each silo
Motor
:
2.2 kW, 415 V
TELESCOPIC CHUT VENT FAN: Number
:
5 no, 1 for each silo
Motor
:
5.5 kW, 415 V
HYDROMIX DUST CONDITIONER: Number
:
15 no, 3 for each silo (2 working, 1 standby)
Capacity
:
200 T / hr
61
ASH HANDLING PLANT
Motor
:
7.5 hp, 415 V
MIX SPRAY PUMPS: Capacity
:
196 m3 /min
Drive
:
Motor
Nos.
:
2 pumps in service and 1 pump in standby condition.
Working pressure :
10-12 kg/cm2
Mix spray water pumps are used for HMDC nozzles to condition the dry ash which passes through it. M.S. Pumps are also used for flushing of hydrobin decanters & slurry lines etc.
INSTRUMENT AIR COMPRESSORS: Number
:
3 no, (2 working, 1 standby)
Flow Rate
:
14 m3 /min (each)
: :
1.8 kg /cm2 8.0 kg /cm2
:
125 kW / 415 V
Dish. Pressure
Stage-I Stage-II
Motor
AIR DRYING PLANT : Capacity
:
1800 N m3 /hr
BOTTOM ASH HOPPER: Number
:
4 no, 1 for each unit
:
Water Impounded
Hopper
:
2 per boiler
Capacity
:
196 m3 (128 T)
Discharge Gate
:
4 no per hopper
Type Section of
COARSE ASH TANK: No
:
4 no, 1 for each unit
Capacity
:
38 m3
CLINKER GRINDERS: 62
ASH HANDLING PLANT
Number
:
16 no, 4 for each unit (2 running, 2 standby)
Type
:
Double roll
Make
:
Indure
Capacity
:
70 T / hr
Motor
:
7.5 kW / 415 V
Gear Box Ratio :
7.52 : 1
Fluid Coupling :
960 rpm
HYDRO EJECTORS (JET PUMP): Number
:
24 no, 6 no per unit (4 for Bottom Ash Hopper, 2 for Coarse Ash Tank)
Make
:
Indure
Size
:
152 mm*100 mm*150 mm (Inlet*Throat*outlet)
Nozzle size
:
44 mm
Capacity
:
70 T /hr
Head
:
208 MWC
Flow
:
400 m3
OVER FLOW TANK: Capacity
:
54 m3
OVERFLOW PUMP: Number
:
8 no, 2 per unit (1 working, 1 standby)
Make
:
Indure Ltd., Sahibabad, U.P.
Capacity
:
245 m3 /hr
Dish. Pressure
:
2.8 kg /cm2
Motor
:
45 kW / 415 V
Number
:
6 no, 3 for unit 1 & 2 and 3 for unit 3 & 4
Capacity
:
650 T
:
10.6 m
HYDROBINS:
Top Diameter
Vibrofeeder Motor:
2*4 kW / 415 V / Opposite direction
63
ASH HANDLING PLANT
SETTLING TANK: Number
:
2 no (one for unit 1&2 and one for unit 3&4)
Capacity
:
750 m3
:
20.02 m
Number
:
2 no (one for unit 1&2 and one for unit 3&4)
Capacity
:
1500 m3
:
23 m
Top Diameter
SURGE TANK:
Top Diameter
SLUDGE PUMPS: Number
:
8 no, 2 for each Settling tank & Surge tank (1 working, 1 standby)
Seal Water Pr.
:
3.5 kg /cm2
Capacity
:
50 m3 /hr
Dish. Pressure
:
3.0 kg /cm2
Motor
:
11 kW/ 415 V
HIGH PRESSURE WATER PUMP: Number
:
6 no (3 for unit 1 & 2, 3 for unit 3&4)
Make
:
Becon Weir Ltd.
Type
:
Multi Stage, Single Suction Centrifugal
Number of Stages :
7
Capacity
:
110 Litres / sec (For Hp-1, 2, 3) 112.78 Litres / sec (For Hp-4, 5, 6)
Head
:
208 Mwc (For Hp-1, 2, 3) 176 Mwc (For Hp-4, 5, 6)
Motor
:
320 kW / 6.6 kV
LOW PRESSURE WATER PUMP: Number
:
6 no (3 for unit 1 & 2, 3 for unit 3&4)
Make
:
Becon Weir Ltd.
Type
:
Single Stage, Double Suction Centrifugal
Capacity
:
81.7 Litres / sec
Head
:
63 Mwc
64
ASH HANDLING PLANT
Motor
:
75 KW
/ 415 V
MIXER SPRAY WATER PUMP: Number
:
3 no
Make
:
Becon Weir Ltd.
Type
:
Multi Stage, Double Suction Centrifugal
Number of Stages :
2
Capacity
:
81.7 Litres / sec
Head
:
63 Mwc
Motor
:
75 kW
/ 415 V
SEAL WATER PUMP: No
:
2 no, (1 working, 1 standby)
Make
:
Becon Weir Ltd.
Model
:
Fnd-9
:
Multi Stage Centrifugal Type
Type
Number of Stages :
7
Capacity
:
8.3 Litres / sec
Head
:
216 Mwc
Motor
:
45 KW / 415 V
BOOM SPREADER MACHINE (SP-1): The crawler mounted spreader machine forms the backbone of the dry ash handling system at NTPC Dadri. As the name suggests, the 300 MT machine while traveling on the crawler pads spreads and feeds ash to the permanent ash mound. Besides the long travel at approx. 6.0 meters/minute, the spreader discharge boom can slew with the machine super structure within the angle range of + 145 degree and be luffed in the vertical plane from 3 to 16 degrees making it possible to attain maximum dumping height of 15.5 meter. The magnificence of this wonder machine can be judged by the fact that it is guaranteed to give ash output of 2000 T /hr. It has already dumped approx. 68.00 lacs T. of ash on the ash mound during last five years operation.
FLY ASH TRANSPORT LINE:
LENGTH OF PRESSURE
UNIT -I
UNIT -II
UNIT -III
UNIT -IV
2 * 1 km
2 * 1.1
2 * 0.9
2 * 0.85
65
ASH HANDLING PLANT
LINE
km
km
km
50 meter
50 meter
50 meter
10 meter
10 meter
10 meter
80 meter
80 meter
80 meter
10 meter
10 meter
10 meter
a) A.C.I. (3OO NB ) 50% b) CAST BASALT(350 NB) 50% LENGTH OF ESP Vac. LINE a) A.C.I. (2OO NB) b) A, C. I (250 NB) LENGTH OF APH Vac. LINE
50 meter 10 meter
a) A.C.I. (2OO NB) b) A, C. I (250 NB)
80 meter 10 meter
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ASH HANDLING PLANT
INTRODUCTION OF MOBILE EQUIPMENTS: Mobile equipment stated there are the, equipment which are being used for the construction of ash mound and spreading of ash stacked by spreader system. Bulldozer/zero is being used for spreading of stacked ash on ash mound. Bulldozers also work as compactors because of the weight. Moor grader is used for leveling of ash. Vibratory rollers are used for compaction after final leveling is completed pipe layer is used for shifting of field conveyor. Other equipment such as Pay Loader, Excavator, Articulated Dump Truck, Tata Dumper etc. are used for lifting & shifting of ash from one place to an other place for land filling. Bowsers are water sprinklers with 5 Kl. Capacity tank. water spray on ash mound and nearby areas.
It is used for
LIST OF MOBILE EQUIPMENTS: 1.
DOZER D-355
:
1 No.
2.
DOZERS D-155
:
3 Nos.
3.
DOZERS D-50
:
2 Nos.
4.
VIBRATORY ROLLER
:
2 Nos.
5.
PAY LOADER
:
1 No.
6.
MOTOR GRADER
:
1 No.
7.
EXCAVATOR
:
1 No.
8.
ARTICULATED DUMP TRUCK
:
2 Nos.
9.
BOWSER
:
3 Nos.
10.
DUMPER
:
2 Nos.
11.
PIPE LAYER
:
1 No.
:
2 Nos.
:
1 No.
12. 13.
TRACTOR CRANE
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ASH HANDLING PLANT
REQUIREMENT & OPERATION OF VARIOUS MOBILE EQUIPMENTS: DOZER: The dozers are required for spreading, leveling and ramping the ash deposited by the boom spreader. As discharge from the boom spreader generally falls in a pile 15 M. high and will not be level nor to the specific angle required. The bulldozers provide trimming. Operation of dozers reduces the boom spreader movement particularly when it reaches at limit. Generally two D-155 dozers or one D-155 and one D-355 dozers are used for this purpose. These two dozers are also used to from the graded side and face slopes to their rough profifles and any temporary ramps and accesses. One small dozer D-50 is being used in temporary stock yard for helping the reclaimer to collect the ash near reclaimer bucket. This small dozer is also used for making ditch slopes and lagoon area for filter bed preparation.
VIBRATORY ROLLER: ROLLER: Vibratory roller is basically a compactor cum roller. This is used for compacting ash throughout the ash mound on place surface on top of mound and also on slopes. This is operated after leveling of ash on mound surface and after reaching to required level at final stage.
PAY LOADER: Requirement of Pay Loader is not connected with ash mound construction. Pay Loader is used to lift and load ash in dumpers bucket for transportation of ash from ash mound to other low laying areas or to fill the rain cuts, pay loader is also used to remove the mud and silt taken out from ditches by other machines.
EXCAVATOR: Requirement of Excavator has been felt for making peripheral ditch around ash mound & drains around ash mound. Ditch and drain cleaning was also a major problem and it was not possible to clean them manually. As before every rainy season ditch and drain cleaning was essential we preferred to purchase a excavator for this purpose. The additional work which has a major role is lifting & shifting of ash from ash mound area to other places, in the excavator plays a major role as filling of dumpers are easy with the help of excavator. Even though we 68
ASH HANDLING PLANT
have one pay loader but it was not sufficient to fill the dumpers. With help of excavator we have reduce idle time of dumpers.
MOTOR GRADER: Motor Grader is a leveler / planner. It is having a small blade between its front and rear tyres. It is used for final leveling of ash on mound and slopes to get the final profile.
ARTICULATED DUMP TRUCK: Articulated Dump Truck is being used to deposit ash in areas physically out of reach of the boom spreader. This dump truck is also used for shifting of ash from ash mound to other low laying areas for land filling purpose.
BOWSER: As water spreaying is an essential task in ash mound construction and to reduce dust emission. Bowsers are procured for this purpose. Bowser are basically water spraying vehicle. Bowser is consists of 5 Kl. Capacity tank mounted on chasis, engine driven centrifugal pump is installed on the chasis with water meter, valves, hose recl. And spray nozzles. The operation of rear engine and nozzles etc. are controlled from driver’s cabin. There bowser are also used for spraying of polymers on the ash mound finished surface to suppress dust. Polymer spray on surface on mound makes a thin film of polymer on mound surface which eliminates the dust emission even in storm.
PIPE LAYER: Pipe Layer is specially designed equipment for shifting of field conveyor a special attachment was fabricated and fitted on bulldozer model D-155 for this purpose. This pulls field conveyor along its complete length in a step of 0.5 m at a time.
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ASH HANDLING PLANT
ASH UTILIZATION: UTILIZATION: •
OPC
•
PPC (Portland Pozzolana Cement)
•
Concrete
•
Road Construction
•
Embankments
•
Land Development
•
Structural Fills
•
Lightweight Aggregates
•
Lime-Fly Ash Bricks
•
Clay-Fly Ash Bricks
•
Insulating bricks
•
Mineral Wool
•
Cenospheres
•
Colored Bricks
70
