Ash Handling System for EET-r3
Transcript of Ash Handling System for EET-r3
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Ash HandlingSystem
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WHY ASH HANDLING?Ash content of Indian coal used in power station is about 30 to 40 %.
A typical 2000 MW station produce around 9000T to 12000T of ash per day.This huge amount of ash needs to be disposed off continuously.
Necessary care to be taken for preventing pollution
Ash Handling system takes care the above requirement
Typical Ash Data
210 MW 500 MW 660 MW
TOTAL ASH 75 180 240
BOTTOM ASH 11.25 28 36
ECONOMISER ASH 2.25 6 7
AIR PREHEATERASH
1.5 4 5
ESP ASH 60 144 192
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WHAT HAPPENS TO THE ASH
PRODUCED?20 % Of the ash falls at the bottom of the furnace known
as Bottom Ash (BA).
80 % of the ash carried away with flue gas known as Fly
Ash.BA can form slag and clinker depending on the temp.
of the combustion zone and environment inside.
reducing environment (Less O2) reduces ash MP.BA is disposed off through BA disposal system.
FA is collected through ESP and disposed through FA
disposal system.
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Coal Seam
Surge Pile
Pulverize (-150)
Overburden
Fly Ash
Flue Gas
Electrostatic Precipitator
Flue Gas
Boiler
Fly AshBottom Ash
SmokeStack
Fly AshBottom
Ash
Schematics of Ash Generation
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Ash volumes and properties
ESP
Pulverized
Coal
Furnace
(1300 - 1500C)
Electrostatic
Precipitator
Sta
geA:80%
Sta
geB:17%
80-90 %
Sta
geC:3%
Fly ash
Air
preheater
APH
Economizer
Eco Ash APH Ash
1 % 1 %
Stack
Fineness
Bottom AshCoal
10-20 %100 % Ash
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Bottom Ash HandlingSystem
Wet Type
Continuous
ScrapperConveyor
ScrewConveyor
Intermittent
Jet Pump /Ejector
Dry type
Pneumatic Conveyor
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BA Handling SystemBA can be collected at furnace bottom as Wet or Dry form.
Wetbottom ash system consists of i)Trough seal, ii)BA
gate, iii)Hopper, iv)Scrapper Conveyer, v)Clinker grinder,
vi)BA trench, vii)BA tank, viii)BA pump, ix)BA pond.
DryBA consists of i)Trough seal, ii)BA gate, iii)Hopper,iv)Scrapper Conveyer, v)Clinker grinder, vi)Silo.
Trough seal: A channel around the furnace bottom
filled with water where the furnace bottom end is
immersed in water. This is to prevent air ingression in the
boiler during operation.
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BA Handling System
BA Gate: Each hopper has separate gate to isolate Scrapper conveyorfrom running furnace for any repairing at scrapper.
Scrapper Conveyer : Consists of number of scrapper bars fasten atboth the ends with two chain which can run on chain pulley and drivenby scrapper conveyor motor. The whole conveyor is submerged inwater for wet BA system. Bottom ash after falling on scrapper isscrapped away by the running conveyor to one end of the conveyor toclinker grinder.
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SCRAPER CHAIN CONVEYOR
ONE REFRACTORY-LINED TRANSITION HOPPER WITH ISOLATION GATES FOR EMERGENCYSTORAGE OF ASH FOR 3 TO 4 HOURS
2 X 100% ( ONE WORKING + ONE STANDBY) , OR 2 X 50% (TWO WORKING + TWO STANDBY)DEPENDING ON SUPPLIERS CAPABILITY
WATER SUPPLIED CONTINUOUSLY
FOR SPRAY-QUENCHING OF ASH IN TRANSITION HOPPER
FOR COOLING OF ASH IN TROUGH. OVERFLOW WATER FROM TROUGH RECYCLED IN ASHHANDLING PLANT AFTER SETTLING OUT CARRY OVER ASH
DEWATERED ASH FALLING FROM SSC SLUICED THROUGH TRENCH TO LOCAL BOTTOM ASH
SLURRY SUMP BOTTOM ASH
SLURRY PUMPED OUT BY HEAVY DUTY CENTRIFUGAL PUMPS TO MAIN SLURRY DISPOSAL
PUMPHOUSE
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Wet Bottom Ash System with Scrapper Conveyor
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BA Handling SystemClinker grinder : Any big size ash clinker is crushed to enable to becarried away by water jet through BA trench.
BA trench : Through water jet ash slurry is carried awayto BA tank
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SCREW CONVEYOR
ONE TRANSITION HOPPER PER UNIT
WATER SPRAYED ON BOTTOM ASH FALLING THROUGHHOPPER FOR QUENCHING
ASH FALLS INTO TROUGH BELOW HOPPER
ONE SCREW CONVEYOR ,INCLINED UPWARDS,PROVIDED IN TROUGH TO REMOVE THE ASH
CONTINUOUSLY DEWATERED ASH SLUICED VIA TRENCH TO SLURRY
DISPOSAL PUMPHOUSE
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WATER IMPOUNDED HOPPER WITH JET PUMPS
HOPPER EVACUATED ONCE IN 4 HOURS OR 8 HOURSUSING JET PUMPS SUPPLIED WITH HIGH PRESSURE
WATER FROM DEDICATED PUMPS. ASH SLUICED VIA
PIPELINES TO MAIN SLURRY PUMPHOUSE.
LOWER CAPITAL COST
EASIER MAINTENANCE- FEWER MOVING PARTS
HOPPER DISCHARGE GATES LEAKAGEPRONE
HIGHER WATER AND POWER CONSUMPTION OVERALL OF ASHPLANT DUE TO UNEVEN WATER AND SLURRY FLOWS
WIDELY EMPLOYED
PROS AND CONS
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Dry BA Handling System
DryBA collection system after clinker grinder collect ash
to silo through a transport mechanism for further transportthrough road system.
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ECONOMISER ASH HANDLING SYSTEMS
WET TYPE
- FLUSHING BOX
- FEEDER EJECTOR
DRY TYPE
VACUUM TYPE PNEUMATIC CONVEYING PRESSURE TYPE PNEUMATIC CONVEYING
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ECO ASH SYSTEMS
FLUSHING BOX BASED SYSTEMS CONTINUOUS ASH REMOVAL
CAN BE COMBINED WITH CONTINUOUS -TYPE BOTTOM ASHREMOVAL SYSTEMS( SSC , SCREW CONVEYOR) TO OPTIMISEWATER AND POWER CONSUMPTION AND LAYOUT
PREFERRED , AS HOT ASH IS CONTINUOUSLY COOLED AND
REMOVED
FEEDER EJECTOR BASED SYSTEMS INTERMITTENT ASH REMOVAL
CAN BE COMBINED WITH INTERMITTENT TYPE BOTTOM ASH
REMOVAL SYSTEMS (WIH) TO OPTIMISE WATER AND POWERCONSUMPTION AND LAYOUT
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AIR PREHEATER ASH REMOVAL
SYSTEMS
SIMILAR TO ECONOMISER ASH REMOVAL SYSTEMS
RELATIVELY EASIER DUE TO LOWER ASH
TEMPERATURE( 150-200 DEG. C)
MAY BE COMBINED WITH ESP DRY ASH REMOVAL
SYSTEM
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Dry FA Handling System
Hydrobackter is a vacuum device to collect ash from thehopper.
Water jet ejectors used for creating vacuum.
Dry ash thus collected to silo through belt conveyor.
Dry ash is disposed through road transport to a dry ash
disposal system. Part of it sold for commercial purpose
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ESP ASH REMOVAL SYSTEMS
ESP AshRemoval
Wet
Continuous Intermittent
Dry
DryExtractionfrom Silo
PressureType
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FA Handling SystemFA is collected from Air heater hopper, Eco hopper andESP hopper.
Either through flushing apparatus or hydrobactur system.
In Flushing apparatus system ash is allowed to fall influshing apparatus under gravitation.
Water jet in flushing apparatus carries away the ash to FAtrench
High pressure jets further carries it to FA sump.Series pumping carries the ash slurry to FA pond.
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ESP ASH REMOVAL SYSTEMS
CONTINUOUS TYPE
- FLUSHING BOX AND TRENCH SLUICE (WET
SYSTEM)
- PNEUMATIC TYPE (DRY SYSTEM)
INTERMITTENT TYPE
- FEEDER EJECTOR AND TRENCH SLUICE (WETSYSTEM)
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ESP ASH REMOVAL SYSTEMS
(AS PER STATUTORY REQUIREMENTS)
DRY ASH EXTRACTION FROM ESP
PROVISION OF ASH SILOS FOR SALE OF ASH
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ESP ASH EXTRACTION
SYSTEMS
DRY CONVEYING FROM ESP HOPPERS , AND
FURTHER REMOVAL EITHER BY WET SYSTEM AS
SLURRY FOR ONWARD DISPOSAL TO ASH POND OR BY
DRY SYSTEM TO STORAGE SILO FOR SALE
PNEUMATIC SYSTEMS
- VACUUM TYPE- PRESSURE TYPE
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ESP ASH REMOVAL SYSTEMS
VACUUM TYPE SYSTEMS
- SUITED FOR REMOVING MATERIAL FROM MANYCOLLECTION POINTS AND DISCHARGE TO ONEPOINT(ESP)
- MATERIAL CONVEYED AS A SUSPENSION IN THE PIPEAT HIGH VELOCITIES
- VACUUM PRODUCED USING
- LIQUID-RING VACUUM PUMP, IF ASH IS TO BE CONVERTEDTO SLURRY FOR DISPOSAL
- LOBE-TYPE AS VACUUM PUMPS IF ASH IS TO BE HANDLEDDRY
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VACUUM TYPE SYSTEMS PROS AND CONS
SIMPLE LAYOUTDOES NOT REQUIRE MUCH HEADROOM BELOWESP
SIMPLE IN OPERATION
NO LEAKAGE OF ASH
EASY TO MAINTAIN
HIGH WEAR AND TEAR ,ESPECIALLY AT VALVES AND BENDS
RESTRICTION ON CONVEYING RATE/DISTANCEMAX. 60 TPH/150 M.
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PRESSURE SYSTEMS
LOW
PRESSURE
MEDIUM
PRESSURE
HIGH
PRESSURE
MATERIALTRANSPORT MODE
SUSPENSION PARTLY INSUSPENSION,
PARTLY ASMOVING BED
SLUG (DUNE ORPLUGS FILLINGWHOLE PIPESECTION)
TYPICALCONVEYING AIRPRESSURE (BAR)
1-1.5 1.5-3 >3
TYPICAL AIR/ASHRATIO BY WT.
10-15 20-30 >50
TYPICALCONVEYINGVELOCITIES(M/S)
20-25 10-15 5-8
TYPICAL AIRSOURCE
BLOWER/COM-PRESSOR
SINGLE-STAGESCREWCOMPRESSOR
TWO-STAGESCREWCOMPRESSOR
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ESP ASH HANDLING
SINGLE STAGE CONVEYING TO SILO BY
VACUUM SYSTEM IF TONNAGE IS WITHIN 60 TPHAND/OR DISTANCE IS WITHIN 150 M
OTHERWISE, PRESSURE SYSTEM FOR DISTANCEWITHIN 400M FROM ESP
TWO-STAGE CONVEYING SYSTEM FOR DISTANCE MORETHAN 400M
VACUUM EXTRACTION+PRESSURE TRANSPORTATION
PRESSURE EXTRACTION+PRESSURETRANSPORTATION
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ASH SLURRY DISPOSAL
BOTTOM ASH AND FLY ASH DISPOSED OFF AS COMBINEDSLURRY
ASH PUMPED AS LEAN SLURRY MAX. 25% FOR BA/BA+FA
MAX. 30% FOR FA ONLY
HORIZONTAL, CENTRIFUGAL ,SLURRY DUTY PUMPS USED PUMPS COUPLED IN SERIES TO ACHIEVE DESIRED TOTAL HEAD
TYPICALLY FOUR PUMPS PER SERIES TO PUMP UPTO 10KM
TOTAL NO. OF DISPOSAL SERIES IS NO. OF UNITS +2
GARLANDING OF ASH POND FOR EFFECTIVE FILLING ANDCONSTRUCTION AND OPERATIONAL FLEXIBILITY
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Ash Pipe line System
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ASH WATER SYSTEM
RAW WATER,CW BLOWDOWN, RECYCLED WATER FROM
ASH POND USED FOR ASH SLUICING
CLARIFIED WATER FOR SEALING/COOLING
HORIZONTAL, CENTRIFUGAL PUMPS WIDELY USED LESSER COST
EASIER TO INSPECT AND MAINTAIN
ASH POND WATER RECYCLED TO SAVE ON WATERCONSUMPTION AND FROM ENVIRONMENT ANGLE
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BA Handling System
BA pump : Ash slurry handling pump. It carries ash to the BA pond.Depending on the distance of BA pond two or more BA pumpsconnected in series.
BA pond : Finally ash is discharged to ash pond. It is a large areasurrounded by embankment. Ash mixed with water is allowed to settle
for considerable time. Water from top surface is allowed to go out fromthe pond through a designed escape route. Quality of water discharge isalways monitor for turbidity and heavy metal. Piezo meter is used formonitoring the slope stability of the embankment.
BA Supporting water pumpsLP BA pump : Supply water to trough seal, scrapper conveyor sump,BA sump and LP jets.
HP BA pump : HP jets in BA trench and line cleaning.
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Typical Ash Dyke Design
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Typical Ash Dyke Design
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Ash Pond in Google Map
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Initially in an endeavor to utilize around 100 MMT of ashgenerated in the country Ministry of Environment and Forest
(MoEF) came up with a notification (S.O. 763(E) Dt.
14.9.1999)(Annexue-5) which allows the ash users (e.g.-
Cement companies, Asbestos manufacturing companies,
brick manufacturers etc.) to take ash "Free of cost" from
power generating companies till Sep-2009. During the period of ten years, ash utilization has increased
from 12% to 40% and is growing at fast rate. Ash user
companies especially Cement, and Asbestos sheet
manufacturing companies used this opportunity and
exploited pozzolanic properties of ash by using ash as a raw
material in the manufacturing of their products. In line with the practices followed in western countries, like
USA and Europe, in April -2007 Ministry of Environment and
Forest (MoEF) came up with a draf t not i f icat ion w hich allow
sale of Ash
Ash Utilization Govt Initiatives
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ASH UTILISATIONMajor usage of ash
Fly ash bricks / blocks
Cellular concrete products
Light weight aggregates
Concrete and mortar
In manufacture of cementIn manufacture of asbestos products
Road construction
Embankment/back fills/land development
Controlled low strength material (CLSM)In agriculture
Mine filling
Manufacture of fertilizer
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Other usageManufacture of distemper
Floor and wall tiles
Refractory bricks
Manufacture of ceramics
Use with Ferro cement
Recovery of metalsUse in grouting
Manufacture of alum
Extraction of Cenospheres
Domestic cleaning powderIn synthetic wood
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THANK YOU
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Direct Disposal