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ASH HANDLING SYSTEM

Indian coal contains >30% of ash. The hourlyconsumption of coal of a 200 MW unit is about 110 tons.With this, the hourly production of ash ill be 33 tons. !sh hich as a

ma"or en#ironmental concern is fast becomin$ a useful resource,promotin$ technolo$ical ad#ancements in ash collection and stora$esystems ith in built facilities for bul utili&ation applications as ell asmeetin$ stricter en#ironmental norms.

Method of 'ollection'on#eyin$

(neumatic

MechanicalInterim stora$e)isposal of #arious types of ash residue

*ottom ash'rushed in cliner $rinder

*ed ash+ly ash

)ust 'ollectors *a$house-/(

!sh 'liners

To types of !(

)ry ash system+rom /( hopper, etc to silos

!sh slurry system!sh from furnace bottomWater impoundment at bottom/caper 'hain 'on#eyor'liner rinder produces ash slurry

/ystem 'omponents

1.!ir Intae2. +ully nclosed, uic !ctin$, /in$ )isc #al#e3. (ipe +ittin$s ith 4eplaceable, 4e#ersible, Interchan$eableWearbacs 550 *6-

7. (addle Type !sh 'onditionin$ 8nit5.!brasion 4esistant centrifu$ally 'ast'on#eyor (ipe9. /ilo :ent +ilter

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;.'entrifu$al 4ecei#er

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/T!TID6 '!(!'ITE A =70 MW

'D!C 'D6/8M(TID6 A 3.99 Million T < Eear

!/ 64!TID6 A 1.5 Million T < Eear

!/ )I/(D/!C A )ry !sh /ystem

)4E !/ /E/TM A :ac. @traction (r. Transportation W!T4 4MT. +D4 !/ 'D6)ITID6I6 A 20 % by Wei$ht

!/ MD86) !4! A 3;5 acre

DRY ASH HANDLING SYSTEM AND ITS ADVANTAGES

! LESS RE"#IREMENT $% LAND&! LESS 'ATER RE"#IREMENT(! ELIMINATES #NDERGR$#ND 'ATER AND S#RR$#NDING

'ATER 'AYS P$LL#TI$N)! %A*ILITATE LARGE S*ALE #TILI+ATI$N $% ASH,! PR$GRESSIVE REST$RATI$N $% ASH DISP$SAL SITE AS

#SE%#L LAND

SALIENT %EAT#RES $% INSTALLED SYSTEM-

@traction transportation of fly ash in complete dry form.

/ystem ha#in$ pro#ision to store selected $rade of ash in separate/ilo /iloF3-.

'omplete reFcirculation of ater for *ottom !sh andlin$ /ystem.

8nloadin$ Transportation of conditioned ash from /iloGs decanted bottom ash from ydrobins on to belt con#eyorGs.

'onstruction of !sh Mound in a systematic manner.

T./ ty0es /1 AHS

Dry Ash System 2 %r/m ESP3APH h/00ers t/ Sil/s thr/ughDry Ash Handling System

& 4/tt/m Ash H/00ers3Ec/n/mi5er H/00ers t/ Hydr/6insthr/ugh 'et Ash Handling System 7 %inally sent t/ Ash M/und

THE ASH M$#ND-Dut of 500 acres of land for the dry ash disposal system, ash moundill spread o#er an area of 3;5 acres hich ill $o up to a hei$ht of 55meters ith top most flat area of 170 acres. The ma@imum side slope

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of ash mound ill be 1A7 it ill hold 53 million cubic meters of ash. !shmound system is desi$ned for 25 years ash output of four 210 MWunits one 500 MW unit.

The mound desi$n co#ers stability, erosion and en#ironmental

considerations of noise dust and aterborne pollution.

!CT46!TI:/

*DTTDM !/ /E/TM

+CE !/ /E/TM

/C844E )I/(D/!C !6) !/ W!T4 4'D:4E /E/TM

*DTTDM !/ !6)CI6 /E/TM

/crapper 'hain and *elt 'on#eyor

+CE !/ !6)CI6 /E/TM

)ense (hase (ressure type

!/ )I/(D/!C /E/TM

Cean /lurry )isposal /ystem

Typ *ottom !sh /ystem*ottom !sh opper

Typ 7hr stora$e capacity/crapper 'on#eyor'liner rinder

/in$le

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Truc

Typ +ly !sh /ystem!(

!sh feed rate from the ash stora$e silo is preciselycontrolledWater spray feed rate is ad"usted by control #al#es.'on#eyin$ action pro#ided by the rotatin$ paddles

pro#ides continuous flo of uniformly mi@ed ash ith noe@cess ater or dustin$.

'losed

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What is Ash?

Ash is the residue remaining after the coal is incinerated

!om"osition of ash handling s#stem?

Si$%& Al%$'& (e%$'& !a$ & Mg$

Wh# Ash Handling S#stem is re)uired?

In Thermal *o+er *lant,s coal is generall# used as fuel and hence the ash is"roduced as the -#"roduct of !om-ustion Ash generated in "o+er "lant is a-out

'./0.1 of total coal consum"tion and hence the s#stem is re)uired to handle Ash

for its "ro"er utili2ation or dis"osal

Ash terminolog# in "o+er "lants?

(l# Ash 3 Around 4.1 is the 5alue of fl# ash generated6

7ottom ash 37ottom ash is %.1 of the ash generated in coal -ased "o+er stations

What is fl# ash?

Ash generated in the ES* +hich got carried out +ith the flue gas is generall#called (l# ash It also consists of Air "re heater ash 8 Economiser ash 3it is a-out

% 1 of the total ash content6

What is -ottom ash?

Ash generated -elo+ furnace of the steam generator is called the -ottom ash

9olume of ash and "ro"erties

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System Description

The ash handling s#stem handles the ash -# -ottom ash handling s#stem& coarse ash

handling s#stem& fl# ash handling s#stem& ash dis"osal s#stem u" to the ash dis"osal area

and +ater reco5er# s#stem from ash "ond and 7ottom ash o5erflo+ Descri"tion is as

follo+s:

; A. Bottom Ash Handling System

7ottom ash resulting from the com-ustion of coal in the -oiler shall fall into the o5er

ground& refractor# lined& +ater im"ounded& maintained le5el& dou-le 9/Section t#"e< Wt#"e steel/ fa-ricated -ottom ash ho""er ha5ing a hold u" 5olume to store -ottom ash and

economi2er ash of ma=imum allo+a-le condition +ith the rate s"ecified The slurr#

formed shall -e trans"orted to slurr# sum" through "i"es

; B. Coarse Ash (Economizer Ash) handling System

Ash generated in Economi2er ho""ers shall -e e5acuated continuousl# through flushing

-o=es !ontinuous generated Economi2er slurr# shall -e fed -# gra5it# into res"ecti5e-ottom ash ho""er "i"es +ith necessar# slo"e

; C. Air Pre Heater ash handling system

Ash generated from A*H ho""ers shall -e e5acuated once in a shift -# 5acuumcon5e#ing s#stem connected +ith the ES* ho""er 5acuum con5e#ing s#stem

http://thermalpowerplant.files.wordpress.com/2011/04/ashhandllingsystem.jpg

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; D. Fly Ash Handling System

(l# ash is considered to -e collected in ES* Ho""ers (l# ash from ES* ho""ers

e=tracted -# 9acuum *um"s u" to Intermediate Surge Ho""er cum 7ag (ilter for furtherDr# !on5e#ing to fl# ash silo

>nder each surge ho""er ash 5essels shall -e connected +ith $il free scre+ com"ressor

for con5e#ing the fl# ash from Intermediate Surge Ho""er to silo Total fl# ash generated

from each unit +ill -e con5e#ed through streams o"erating simultaneousl# and in"arallel

; E. Ash Slurry Disposal System

7ottom Ash slurr#& (l# ash slurr# and the !oarse Ash slurr# shall -e "um"ed from the

common ash slurr# sum" u" to the d#e area +hich is located at a distance from Slurr#"um" house

/tats

ourly consumption of ash is 33 tons.

The most common types of ash include bottom ash 30F70% in

+*'- and fly ash 90F;0% in +*'- resultin$ from the combustion Cess than 1% of ash produced

95% of fly ash produced is disposed of in landfills and ash ponds

!rea under ash in IndiaA 190 m2

+ly !sh reuseA

*rics, (ortland cement, mbanments and structuralfill,/tabili&ation of soft soils, etc.

!/ !6)CI6

Method of collection, con#eyin$, interim stora$e and load out of#arious types of ash residue

!sh handlin$ can be of to types

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)ry

Wet

+ly ash handlin$ can either be dry or et

*ottom ash handlin$ is $enerally et until recently because of itshi$her particle si&e around 25 mm -

+ly ash can either be fine or course +ine fly ash has particle si&e form 50 B 200 micron hereas

coarse fly ash has particle si&e $reater than 200 micron .

W!T4 IM(D86)) D((4

Dld process

u$e ater consumption

4ecei#es, Juenches, stores crushes and remo#e bottom ash

!sh is dischar$ed once in 9 to = hours

'liner $rinder is situated belo it

*DTTDM !/ !6)CI6F//'

//' is placed beneath the furnace

/lurry is taen up to a deFaterin$ slope before dischar$in$

Water ser#es as coolin$ medium

Water also acts as airloc for ash hoppers to a#oid air to enterthe furnace

4educed ater usa$e

4educed poer consumption

4educed operational and maintenance cost

)ry bottom ash handlin$

Water is not used

Increased boiler efficiency

4educed impurities in stac

Co maintenance cost and no ater reJuired

!):!6T!/ D+ )4E !6)CI6 D:4 //'

)ilute (hase

*oth #acuum pressure pneumatic systems

i$h #elocity

lo ash F to F air ratio

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)ense phase

(neumatic pressure system con#eyin$ dense ash

Co #elocity

i$h ash concentration

Cess ener$y due to its smaller amount of con#eyin$ air

64!C )/I6 !/('T/

*oiler desi$n and confi$uration

)isposal conditions

Water a#ailability

Type of coal

)esi$n capacity

!sh )isposal

S!I! N$

ALTERNATIVE

MERITS

DEMERITS

1. Cean /lurry)isposal/ystemC/)/-

/iloarealayoutissimple

'heaper

Car$eJuantityof aterreJuired

'i#il cost

is hi$h

2. i$h'oncentration/lurry )isposal/ystem'/)/-

Cessaterconsumption

Cessdisposal areaisreJuire

d

4eJuiresmore spacenear silo

!d#anta$es

!sh spreads in layers enablin$ #ertical fillin$, hence landreJuirement is reduced.

(umpin$ at hi$her concentration, hence lo ater consumption.

/lurry flo rate is drastically reduced.

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Citerally no ater releases out, hence no ater retainin$ dams orreco#ery system is reJuired.

4educed leaches at the ash disposal area.

Coer operatin$ poer consumption.

Coer #elocity, hence lon$er life for pipe line.

!):!6T!/ D+ /ICD /E/TM

'ommercial utili&ation of ash in A B 'ement additi#es. B *ric plants. B 4oad main$, etc.

/a#in$ of ater B a precious commodity.

i$h reliability

Ceast maintenance

n#ironment concernAB In a period, hen en#ironmental protection and aareness is a

ma"or industrial and social concern, )ense (hase pneumaticcon#eyin$, by totally enclosed handlin$ system, is particularlyamenable to the en#ironment.

B !ll con#entional problems of spilla$e, dust, contamination andstora$e are efficiently and successfully eradicated.

ASH GATE 8 H$#SING

The !sh ate and ousin$ installed belo the bottom ashstora$e hopper.

It controls the dischar$e from the stora$e hoppers.

The $ate operation is controlled hydraulically, pro#idin$ asmooth operation hen openin$ and ti$ht seatin$ hen closed.

*LIN9ER GRINDER

'oarse bottom ash or other coarsely si&ed material

4educe si&e for pneumatic con#eyance or other means of ashhandlin$

*Y*L$NES

'entrifu$al ash recei#er

Top of a silo or stora$e hopper

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The $ases after reachin$ the end of the conical portion chan$esits direction and mo#es upards toards the outlet formin$ aninner #erte@.

'ontrol hi$h concentration.

P#LSE :ET D#ST *$LLE*T$RS

4ecei#es the o#erflo airstream from the ash recei#er

'ollects ash particulates on the surface of multiple fiber ba$s

'lean filtered- air o#erflos the top of the dust collector,passin$ to the atmosphere or other processin$.

ASH *$NDITI$NERS

The ash conditioner is a totally enclosed, paddle type mi@erdesi$ned to condition fly ash, bottom ash, and other abrasi#e ordusty materials.

The unit coupled ith a rotary feeder- features the ability toaccurately control both the material feed rate and the atersupply flo rate, as ell as ensure a complete and controlledmi@in$ prior to dischar$e

SL#RRY P#MPS

The slurry solution is pumped usin$ it to land fill or transported

to a slurry to la$oon for stora$e

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ASH #NL$ADERS

Telescopic 8nloadin$ 'hute

! nife $ate is fitted to the ash silo bottom

Telescopin$ interlocin$ cones hich are encapsulated by a

fabric

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*/n

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*loer are connected to the bottom of buffer hopper forfluidi&ed air supply

+rom buffer hopper, it is transferred to Transporter.

+rom Transporter, )ry ash is con#eyed throu$h (ipe lines(neumatic 'on#eyin$-. +or pass ! * the line is !* similarly for

pass ' ) the line is ').

ECH!"#"$% & Flyash Disposal and 'tilization& he ndian Scenario

hermal *o+er stations using "ul5eri2ed coal or lignite as fuel generate large )uantitiesof ash as a -#/"roduct There are a-out 4% "o+er "lants in India& +hich form the ma@or

source of fl#ash in the countr# With the commissioning of su"er thermal "o+er "lantsand +ith the increasing use of lo+ grade coal of high ash content& the current "roductionof ash is a-out 4 million tonnes "er #ear This figure is liel# to go u"to ;.. million

tonnes "er #ear -# the #ear %... AD and "ose serious ecological "ro-lems

A""reciating the o5erall concern for the en5ironment and the need for the safe dis"osal

and effecti5e utilisation of fl#ash& De"artment of Science 8 Technolog# 3DST6 as thenodal agenc# and Technolog# Information and Assessment !ouncil 3TI(A!6 as the

im"lementing agenc# commissioned a (l#ash Mission in ;BB0Flyash Mission: a

Technology Project in Mission Mode 3T*MM6 is -eing im"lemented +ith "artici"ation ofMinistr# of En5ironment 8 (orest& Ministr# of *o+er& Thermal *o+er Stations& C8D

institutions and Industr# The focus is on demonstration of coal ash related technologiesfor de5elo"ing confidence and thus ensuring large scale ado"tion A num-er of "ro@ects

taen u" -# the industr#& C8D institutions and academia ha5e sho+n encouragingresults Some of these "ro@ects ha5e -een com"leted& multi"lier effects ha5e started and

other "ro@ects are heading to+ards meaningful com"letion A @udicious mi= of select

thrust areas ha5e -een taen u" for concerted efforts These include (l#ash!haracterisation& H#draulic Structures& Handling and Trans"ortation& Agriculture related

studies and A""lication& Ash *onds and Dams& Ceclamation of Ash *onds for Human

Settlement& Coads and Em-anments& >nderground Mine (ills and related research"ro@ects

Although the sco"e for use of ash in concrete& -ric maing& soil/sta-ili2ation treatmentand other a""lications has -een +ell recogni2ed& onl# a small )uantit# of the total ash

"roduced in India is currentl# utili2ed in such a""lications Most of the ash generatedfrom the "o+er "lants is dis"osed off in the 5icinit# of the "lant as a +aste material

co5ering se5eral hectares of 5alua-le land The -ul utili2ation of ash is "ossi-le in t+o

areas& namel#& ash d#e construction and filling of lo+/l#ing areas !oal ash has -eensuccessfull# used as structural fills in man# de5elo"ed countries Ho+e5er& this "articular

-ul utili2ation of ash is #et to -e im"lemented in India Since most of the thermal "o+er

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"lants in India are located in areas +here natural materials are either scarce or e="ensi5e&

the a5aila-ilit# of fl#ash is -ound to "ro5ide an economic alternati5e to natural soils

Flyash Characterization and esting

The "ro"erties of ash are a function of se5eral 5aria-les such as coal source& degree of"ul5eri2ation& design of -oiler unit& loading and firing conditions& handling and storage

methods Thus& it is not sur"rising that a higher degree of 5ariation can occur in ash& not

onl# -et+een "o+er "lants -ut +ithin a single "o+er "lant also A change in an# of thea-o5e factors can result in detecta-le changes in the "ro"erties of the ash "roduced The

degree to +hich an# change affects the utili2ation "otential of ash is a function of the

nature and degree of the change and the "articular a""lication for +hich the ash might -eused The "h#sical& geotechnical and chemical "arameters to characteri2e fl#ash are the

same as those for natural soils& eg& s"ecific gra5it#& grain si2e& Atter-erg limits&

com"action characteristics& "ermea-ilit# coefficient& shear strength "arameters and

consolidation "arameters The "rocedures for determination of these "arameters are also

similar to those for soils

Flyash Disposal in Ash Ponds

*rimaril#& the fl#ash is dis"osed off using either dr# or +et dis"osal scheme In dr#

dis"osal& the fl#ash is trans"orted -# truc& chute or con5e#or at the site and dis"osed off-# constructing a dr# em-anment 3d#e6 In +et dis"osal& the fl#ash is trans"orted as

slurr# through "i"e and dis"osed off in im"oundment called ash "ond Most of the

"o+er "lants in India use +et dis"osal s#stem& and +hen the lagoons are full& four -asico"tions are a5aila-le: 3a6 constructing ne+ lagoons using con5entional constructional

material& 3-6 hauling of fl#ash from the e=isting lagoons to another dis"osal site& 3c6

raising the e=isting d#e using con5entional constructional material& and 3d6 raising thed#e using fl#ash e=ca5ated from the lagoon 3ash d#e6 The o"tion of raising thee=isting d#e is 5er# cost effecti5e -ecause an# fl# ash used for constructing d#e +ould&

in addition to sa5ing the earth filling cost& enhance dis"osal ca"acit# of the lagoon The

constructional methods for an ash d#e can -e grou"ed into three -road categories: 3a6>"stream method& 3-6 Do+nstream method and 3c6 !enterline method (ig; sho+s

t#"ical configurations of em-anments constructed using the different methods The

construction "rocedure of an ash d#e includes surface treatment of lagoon ash&s"reading and com"action& -enching and soil co5er

'pstream ethod

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Do*nstream ethod

Centreline ethod

Fig. + ypical ash dy,e raising con-igurations

An im"ortant as"ect of design of ash d#es is the internal drainage s#stem The see"age

discharge from internal surfaces must -e controlled +ith filters that "ermit +ater to

esca"e freel# and also to hold "articles in "lace and the "ie2ometric surface on thedo+nstream of the d#e The internal drainage s#stem consists of construction of roc

toe& .m thic sand -lanet and sand chimne# After com"letion of the final section

including earth co5er the turfing is de5elo"ed from sod on the do+nstream slo"e

Flyash as Fill aterial

Large scale use of ash as a fill material can -e a""lied +here 3a6 fl#ash re"laces another

material and is therefore in direct com"etition +ith that material& 3-6 fl#ash itself is used

-# the "o+er generating com"an# "roducing the fl#ash to im"ro5e the economics of the

o5erall dis"osal of sur"lus fl#ash and 3c6 at some additional cost& fl#ash dis"osal iscom-ined +ith the reha-ilitation and reclamation of land areas desecrated -# other

o"erations

(ills can -e constructed as structural fills +here the fl#ash is "laced in thin lifts and

com"acted Structural fl#ash fills are relati5el# incom"ressi-le and are suita-le for thesu""ort of -uildings and other structures Non/structural fl#ash fill can -e used for the

de5elo"ment of "ars& "aring lots& "la#grounds and other similar lightl# loaded

facilities $ne of the most significant characteristics of fl#ash in its use as a fill materialis its strength Well/com"actedfl#ash has strength com"ara-le to or greater than soils

normall# used in earth fill o"erations In addition& lignite fl#ash "ossesses self/hardening

"ro"erties +hich can result in the de5elo"ment of shear strengths The addition of illite orcement can induce hardening in -ituminous fl#ash +hich ma# not self/harden alone

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Significant increases in shear strength can -e reali2ed in relati5el# short "eriods of time

and it can -e 5er# useful in the design of em-anments

Enironmental Considerations

The en5ironmental as"ects of ash dis"osal aim at minimi2ing air and +ater "ollutionDirectl# related to these concerns is the additional en5ironmental goal of aestheticall#

enhancing ash dis"osal facilities The ash "roduced in thermal "o+er "lants can cause all

three en5ironmental riss / air& surface +ater and ground+ater "ollution The "ath+a#s of"ollutant mo5ement through all these modes are schematicall# re"resented in (ig%

Fig./ Path*ays o- Pollutant oement around Ash Disposal Facility

Air "ollution is caused -# direct emissions of to=ic gases from the "o+er "lants as +ell as

+ind/-lo+n ash dust from ash mound

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-e minimised -# incor"orating engineering measures in the design of ash "onds and

continuous monitoring of surface and ground+ater +ater s#stems

Flyash E0pertise at 1anpur

IIT Fan"ur has "ioneered the de5elo"ment of the ash d#e design in India A num-er ofash dis"osal facilities across the countr# ha5e -een designed at this Institute !urrentl#& a

ma@or technolog# demonstration "ro@ect onAsh Dyke Design: Raising, Maintenance and

Monitorings"onsored -# (l#ash Mission +ith acti5e su""ort from NT*! is -einge=ecuted at the De"artment of !i5il Engineering As a "art of this "ro@ect& a detailed

manual on ash dis"osal "ractice has -een "re"ared to standardi2e the "rocedures for ash

dis"osal across the countr# Another (l#ash Mission s"onsored "ro@ect in5ol5ing detailedgeotechnical and en5ironmental in5estigation of an ashfill site near 7adar"ur& Ne+ Delhi&

is nearing com"letion 7ased on field and la-orator# in5estigations& detailed guidelines

ha5e -een "re"ared for constructing ashfills and "ossi-ilit# of ground+ater "ollution

through leaching of to=ic metals e=amined A national conference&Flyash Disposal and

Deposition: Beyond 2000 AD& organised at the Institute in (e-ruar# ;BBB& looed intoareas such as design of ash dis"osal facilit#& reclamation of ash "onds& structural filling of

lo+/l#ing areas -# fl#ash and the en5ironmental as"ects of ash dis"osal

The "ro-lems related to fl#ash are com"le= and huge& re)uiring a national effort andcommitment The e="ertise a5aila-le at different institutions has to -e full# harnessed to

de5elo" technologies for large scale eco/friendl# utili2ation of fl#ash

2a3i Sinha

Department o- Ciil Engineering

1anpur

e.mail&rsinha4iit,.ac.in

NTPCs Pioneering Activitiesin Ash Utilization Ash dyke raising Dry ash disposal system at NTPC Dadri Use of only fly ash bricks in all types of

b!ilding constr!ctions" #"$ million tonne ash of NTPC Unchahar%as !sed in Allahabad by&pass road byN'A( )*argest ever !se in single pro+ect in(ndia,"

-ine reclamation"

mailto:rsinha@iitk.ac.inmailto:rsinha@iitk.ac.inmailto:rsinha@iitk.ac.in

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Coal Ash is typically !sed in the follo%ingbeneficial applications at coal mines.

Application in Mines

Ne!tralization of acid forming materials/ 0arriers to acid mine drainage )A-D,formation1transport/ 2!bsidence control in !ndergro!ndmines/ 2oil reconstr!ction" Pit filling to reach Appro3imate 4riginal

Conto!r )A4C, in s!rface mines

2ho%&Case Pro+ects on Use of

Ash in Agric!lt!re in 5armers5ields at.2imhadriUnchaharDadri6ihand

Talcher 7Thermal

8nvironmental (ss!es

FlyashFlyash is categorised as high volume low effectwaste under Hazardous Wastes ( Management,Handling & rans!oundary movement " #ules ,$%%'hemically , flyash mainly consists of oides ofsilica, aluminium, )ron and calcium*, !esidestrace of elements li+e arsenic, !eryllium, !oron,cadmium, chromium, chromium ), co!alt, lead,

manganese, mercury, moly!denum etc*

Air Poll!tion ( Dust emission from ash pond) 9ater Poll!tion ) Contamination of gro!nd :s!rface %ater

*and degradation

Coal based plants contrib!te abo!t ;

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capacityCons!med abo!t ? million M3 %ater ann!ally for

disposal of coal ash as in slurry form/ if not !tilized

Directions /NotificationBide notification No"2"4"$#11E

New Power Plants-% . flyash utilisation within - year

?? = flyash !tilisation %ithin years Existing Power PlantsF? = flyash !tilisation %ithin < year

?? = flyash !tilisation %ithin ; years

Bac,ground

Ash dis"osal in thermal "o+er "lants& a highl#en5ironmentall# sensiti5e issue

India is currentl# "roducing in e=cess of ;.. million tonnesof !oal Ash!urrentl#& (l# ash and 7ottom/ash are -eing mi=ed together

and trans"orted h#draulicall# to ash "ondsThe end uses of 7ottom/ash and (l# ash are different& as

their "ro"erties are +idel# different

7ottom/ash is relati5el# coarse as com"ared to (l# ash&

+hich is e=tremel# fine

Mi=ing them during trans"ortation +ould affect the enduses of -oth forms of ash

Slurr# Dis"osal / !urrent Trends:

#o* Concentration Slurry Disposal (#CSD) (C* 5 +6 7 /68)

edium Concentration Slurry Disposal (CSD) (C* 5 967 :68)

a3or dra*;ac,s o- #CSD

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Water consum"tion is 5er# high and +ater reco5er# s#stems areneeded

E=cessi5e +ear due to higher trans"ortation 5elocit# and se+edconcentration "rofile& there-# affecting the life of the "i"eline

Due to e=cessi5e use of +ater& the threat of "ollution of -oth

ground and surface +ater sources e=ists

Bottom Ash

!rushed -ottom ash is e5acuated from the ho""ers using @et "um"sand dis"osed off in form of a slurr#

7ottom ash is a 5er# coarse material and is eas# to handle

Fly Ash

(l# ash is e5acuated from 5arious locations either h#draulicall# or

"neumaticall#In the "neumatic method& ash is trans"orted to a -uffer silo from

+here it can -e gi5en out for utili2ation

In the h#draulic method& ash is trans"orted to a common sum"!entrifugal slurr# "um"s are used to trans"ort the ash slurr# to ash"ond

In most of the thermal "o+er "lants& the concentration of ash in theslurr# is 5er# lo+ and is of the order of ;. ;1 -# +eightThis method is no+n as lo+ concentration slurr# dis"osal 3L!SD6T#"icall# same dis"osal s#stem is used -oth for -ottom ash as +ellas fl# ash

In one of the thermal "o+er "lants 3N!*S& DADCI6 ash is handledin com"letel# dr# form and dis"osed in the form of ash moundHo+e5er& this re)uires s"ecial e)ui"ments

High Concentration Slurry Disposal (HCSD)

The Ash !oncentration is in the range .1 -# +eight or

a-o5eS"ecial "um"s lie Ceci"rocating< Dia"hragmperating at

pressures up to -5 36)?, pressure systems can satisfyconveying capacities over :%% 3H*

H'60 (High 'oncentrationslurry disposal"

2o ash retaining dams or !unds need to !e !uilt*Ash spreads in layers hence, ash mounds

re@uires minimum land*Higher concentration hence, low water

consumption*=ower line sizes*ery little release of water at the disposal area

through rapid drying*2o apprecia!le leachate from the disposal

site*

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0isposal 6ystem (H'60"* he advantages of H'606ystems are

)n =ean phase slurry system, the concentration is

around :9$5., increaseconcentration to appro*

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>nly few cement companies in thisregion, carry fly ash from

silo at present*Farming on cultiva!le lands*iles, 1loc+s and other similar

construction materials* =and filling i*e* levelling land pitfalls for

ur!anization, colony

development and increasing cultivationhectares*

#oad construction*