Air Pollution (QA)

7/26/2019 Air Pollution (QA)

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AIR POLLUTION


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This occurs when the air contains gases,dust, fumes or odour in harmful amounts.That is, amounts which could be harmful t

the health or comfort of humans andanimals or which could cause damage toplants and materials.

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!AT I" AIR POLLUTION #


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$missions %tra&c, industrial, domestic'(eograph) %terrain'eather conditions %rain, winds,humidit)'"eason

Time of da)Population densit)Indoor *s outdoor

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+ATOR" A++$TIN( AIR POLLUTION


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NATURAL AIR POLLUTION

+orest -resolcanoes/ust stormsPollenRadioacti*e deca)


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0AN10A/$ AIR POLLUTION

ehicle emissionsaste disposalPower plants+actoriesoo2ers

+uel


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!AT AR$ T!O"$ I0PORTANT POL

RIT$RIA POLLUTANT"33


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Nitrogen /io4ide5 NO6 7rownish gas originates from combustion %N6

is o4idi8ed'9 NO4 sum of NO, NO6, other o4idN

O8one5 (round le*el O:

Primar) constituent of urban smog

Reaction of O ; NO4 in presence of heat ;light

arbon 0ono4ide5 O

Product of incomplete combustion

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RIT$RIA POLLUTANT"5 $PA "TAN/AR/


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Lead5 Pb

tetraeth)l lead < anti 2noc2 agent ingasoline

Particulate 0atter5 P0=> %P0 6.?'

"mall particles %si8e mentioned along w

"ulfur /io4ide5 "O6

formed when fuel %coal, oil' containing "burned and metal smelting

precursor to acid rain along with NO4

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RIT$RIA POLLUTANT"5 $PA "TAN/AR/


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RIT$RIA POLLUTANT"5 $0I""ION IN U"


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Number of People Li*ing inounties with Air @ualit)oncentrations Abo*e theLe*elof the NAA@" in =

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RIT$RIA POLLUTANT"


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POLLUTANT"5 "OUR$"


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POLLUTANT"5 "OUR$"


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POLLUTANT"5 "OUR$"BTRAN"PORT


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LLUTANT"5 "OUR$"


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Primar) Air Pollutant

!armful substance9 emitted directl) into atmosphere

"econdar) Air Pollutant

!armful substance formed when a primapollutant reacts with substances normallfound in the atmosphere inthe atmosphe

with other air pollutants

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TCP$" O+ AIR POLLUTION


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Aerosols

Particulates solid phase/ust, Ash, +umes

"olid and liDuid"mo2e %from combustion',

oastal aerosolsLiDuidAggregate gases%sulfate,nitrate'(ases

O4, "O4, NO4, PA!,

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Os, NO4,N1organics, !alo1organics0etals, O

"ourcesTobacco, Power plantsIncinerators,AutomobilesIndustr)

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O07U"TIONPOLLUTANT"

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(reenhouse eEect

O8one depletion

Acidi-cation

"mog formation

$utrophication

!U0AN !$ALT!

$cos)stem health

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I0PAT


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!$ALT! $++$T"

AIR POLLUTIO


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Including pulmonar), cardiac,

*ascular, and neurologicalimpairments.

ar) greatl) from person to person.!igh1ris2 groups such as the elderl),infants, pregnant women, andsuEerersfrom chronic heart and lungdiseases are more susceptible to air

pollution.

hildren are at greater ris2 becausethe) are generall) more acti*eoutdoors and their lungs are stillde*eloping.

AIR POLLUTIO$++$T"

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AIR POLLUTIO


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$4posure to air pollution can cause both acute %shterm' and chronic %long1term' health eEects.

Acute eEects are usuall) immediate and oftenre*ersible when e4posure to the pollutant ends. "acute health eEects include e)e irritation, headacand nausea.

hronic eEects are usuall) not immediate and tento be re*ersible when e4posure to the pollutant en

"ome chronic health eEects include decreasedcapacit) and lung cancerresulting from long1tee4posure to to4ic air pollutants

AIR POLLUTIO$++$T"

AIR POLLUTIO


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R$"PIRATORC PRO7L$0"

7oth gaseous and particulate airpollutants can ha*e negati*eeEects on the lungs.

"olid particles can settle on thewalls of the trachea, bronchi, andbronchioles.

ontinuous breathing of pollutedair can slow the normal cleansingaction of the lungs and result inmore particles reaching the lowerportions of the lung.

/amage to the lungs can inhibitthis process and contribute tobronchitis, emph)sema, and

AIR POLLUTIO$++$T"

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Table 1: Sources, Health and Welfare Effects for Criteria Pollutants.

Pollutant Description Sources Health Effects Welfare Effec

CarbonMonoxide(CO)

Colorless, odorlessgas

Motor vehicle exhaust,indoor sources includekerosene or wood burningstoves.

Headaches, reduced mentalalertness, heart attack,cardiovascular diseases,impaired etal development,death.

Contribute to the ormsmog.

!ulur "ioxide(!O

#)

Colorless gas thatdissolves in water

vapor to orm acid,and interact with othergases and particles inthe air.

Coal$ired power plants,petroleum reineries,

manuacture o suluric acidand smelting o orescontaining sulur.

%&e irritation, whee'ing, chesttightness, shortness o

breath, lung damage.

Contribute to the ormacid rain, visibilit& imp

plant and water damaaesthetic damage.

itrogen"ioxide (O

#)

eddish brown, highl&reactive gas.

Motor vehicles, electricutilities, and otherindustrial, commercial, andresidential sources thatburn uels.

!usceptibilit& to respirator&inections, irritation o the lungand respirator& s&mptoms(e.g., cough, chest pain,diicult& breathing).

Contribute to the ormsmog, acid rain, watedeterioration, global wand visibilit& impairme

O'one (O+) aseous pollutant

when it is ormed in

the troposphere.

-ehicle exhaust and certainother umes. ormed rom

other air pollutants in thepresence o sunlight.

%&e and throat irritation,coughing, respirator& tract

problems, asthma, lungdamage.

/lant and ecos&stem

0ead (/b) Metallic element Metal reineries, leadsmelters, batter&manuacturers, iron andsteel producers.

1nemia, high blood pressure,brain and kidne& damage,neurological disorders,cancer, lowered 23.

1ects animals and paects a*uatic ecos&s

/articulateMatter (/M)

-er& small particles osoot, dust, or othermatter, including tin&droplets o li*uids.

"iesel engines, powerplants, industries,windblown dust, woodstoves.

%&e irritation, asthma,bronchitis, lung damage,cancer, heav& metalpoisoning, cardiovasculareects.

-isibilit& impairment,atmospheric depositioaesthetic damage.

Table;%: Sources, Effects of ir Pollutants on Vegetables


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Pollutants Sources Effects on Vegetables

ldeh!des Photoche"ical reactions The upper portions of lfalfa etc. #ill be affected toif %&' pp" of aldeh!des is present for % hrs duration

()one *(+ Photoche"ical reaction of h!drocarbon

and nitrogen o-ides fro" fuelco"bustion, refuse burning, andeaporation fro" petroleu" products.

ll ages of tobacco leaes, beans, grapes, pine, pu"and potato are affected. 0lec/, stipple, bleaching, bspotting, pig"entation, gro#th suppression, and eaabscission are the effects.

Pero-! cet!l$itrate *P$

The sources of P$ are the sa"e aso)one

oung spong! cells of plants are affected if '.'1 ppis present in the a"bient air for "ore than 2 hrs.

$itrogen dio-ide*$(%

High te"perature co"bustion of coal, oil,gas, and gasoline in po#er plants andinternal co"bustion engines.

3rregular, #hite or bro#n collapsed lesion on interctissue and near leaf "argin. Suppressed gro#th is oin "an! plants.

""onia 4 Sulfurdio-ide

Ther"al po#er plants, oil and petroleu"refineries.

5leached spots, bleached areas bet#een eins, blea"argins, chlorosis, gro#th suppression, earl! abscand reduction in !ield and tissue collapse occur.

Chlorine *Cl% 6ea/s in chlorine storage tan/s,

h!drochloric acid "ists.

3f '.1' pp" is present for at least % hrs, the epider"

"esoph!ll of plants #ill be affected.

H!drogen fluoride,Silicontetrafluoride

Phosphate roc/ processing, alu"inu"industr!, and cera"ic #or/s andfiberglass "anufacturing.

Epider"is and "esoph!ll of grapes, large seed fruitand fluorosis in ani"als occur if '.''1 pp" of H0 isfor & #ee/s.

Pesticides 4Herbicides

gricultural operations Defoliation, d#arfing, curling, t#isting, gro#th redu/illing of plants "a! occur.

Particulates Ce"ent industries, ther"al po#er plants,blasting, crushing and processingindustries.

ffects 7ualit! of plants, reduces igor 4 hardness ainterferences #ith photos!nthesis due to plugging lsto"ata and bloc/ing of light.

8ercur! *Hg Processing of "ercur! containing ores,burning of coal and oil.

9reenhouse crops, and floral parts of all egetationaffected abscission and gro#th reduction occur in

the plants.

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NIT ON$R"ION

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There are two s)stems of unit in common5

0ass per unit *olume5 usuall) Fg m1:. The masspollutant is e4pressed as a ratio to the *olume o

"ince the *olume of a gi*en parcel of air is depe

upon the temperature and pressure at the timesampling, the pollutant concentration e4pressethese units should, strictl) spea2ing, specif) thconditions at the time of sampling.

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UNIT ON$R"ION

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T=absolute temperature (K);

P=atmospheri pressure (hPa)( !emember that "elsius # 273 =Kel$i%)

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UNIT ON$R"ION

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olume mi4ing ratio5 usuall) ppm 1 parts per

%=>1G'9 or ppb 1 parts per billion %=>1'9 or ppt per trillion %=>1=6'. This is e4pressed as the raits %pollutant' *olume if segregated pure, to *olume of the air in which it is contained.

Ideal gas beha*ior is assumed and thus the

concentration is not dependent upon temperand pressureas these aEect both the pollutathe air to the same e4tent. As a conseDuencegas laws, a gas present at a *olume mi4ing rppm is not onl) = cm:per =>1Gcm:of pollutedalso = molecule per =>1Gmolecules and has a

ressure of one millionth of the atmos heric

UNIT ON$R"ION

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"ince NOH consists partl) of NO and NO6, the

*olume fraction in air ppb eDuates to a diEerconcentration in Fg m1:depending on the ratNO to NO6. +or this reason air concentrations

NOHare normall) e4pressed as Fg NOH1NO6m

all references assume that NOHis in the form

NO6.

"ome pollutants %e.g. sulphate, nitrate' are pas particles in the air and the concept of a *omi4ing ratio of gases is not ob*iousl) applicaTheir concentrations are normall) e4pressed

in Fg m1:

units.

UNIT ON$R"ION

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g ha1=)ear1=to 2ilo eDui*alents ha1=)ear1=

The unit eD %a 2eD is =>>> eD' refers to molaeDui*alent of potential acidit) resulting fromsulphur, o4idised and reduced nitrogen, as wbase cations.

+or e4ample5

= 2eD N ha1=)r1=is eDual to =J 2g N ha1=)r1=a= 2eD " ha1=)r1=is eDual to =G 2g " ha1=)r1=.

UNIT ON$R"ION


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AIR POLLUTIONONTROL $@UIP0$NT

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AIR POLLUTION5


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Principle

The particles are remo*ed b) the application centrifugal force. The polluted stream is force

*orte4. The motion of the gas e4erts a centrif

force on the particles, and the) get deposited

inner surface of the c)clones

$@UIP0$NTCLON$"

AIR POLLUTION5


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$@UIP0$NTCLON$"5 ON"TRUTION AN/ OP$RATION

The gas enters the inlet, and is

forced into a spiral.

At the bottom, the gasre*erses direction and Kowsupwards.

To pre*ent particles in theincoming stream fromcontaminating the clean gas, a*orte4 -nder is pro*ided toseparate them. The cleanedgas Kows out through the

AIR POLLUTION5


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A/ANTA($"

)clones ha*e a low capital cost

Reasonable high e&cienc) for speciall) designedc)clones.

The) can be used under almost an) operating con

)clones can be constructed of a wide *ariet) of

materials.

There are no mo*ing parts, so there are no mainte

reDuirements./I"A/ANTA($"

The) can be used for small particles

!igh pressure drops contribute to increased costs

operation.

$@UIP0$NTCLON$"

AIR POLLUTION5 $@UIP0$NT


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$@UIP0$NTCLON$"



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A c)clone with a Kow rate of =?> m:Bmin hae&cienc) of M>. $stimate the e&cienc) ifKow rate is doubled.

$@UIP0$NT

@= =?> m:Bmin

@6 :>> m:Bmin

Pt= =>> 1 M> 6>

Pt6BPt= %@=B@6'>.?

+inal $&cienc) =1 Pt6

MG

Problem



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"ettling chambers use the force of

gra*it) to remo*e solid particles. The gas enters a chamber where

the *elocit) of the gas is reduced.Large particles drop out of the gasand are recollected in hoppers.

7ecause settling chambers areeEecti*e in remo*ing onl) largerparticles, the) are used inconunction with a more e&cientcontrol de*ice.

"$TTLIN( !A07$R"$@UIP0$NT

43



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Principle

The -lters retain particles largerthan the mesh si8e

Air and most of the smallerparticles Kow through. "ome of thesmaller particles are retained dueto interception and diEusion.

The retained particles cause areduction in the mesh si8e.

The primar) collection is on thela)er of pre*iousl) depositedparticles.

$@UIP0$NT+A7RI+ILT$R"



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Fabric Filter

$@UIP0$NT+A7RI +ILT$R"



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The eDuation for fabric -lters is based on /law for Kow through porous media.

+abric -ltration can be represented b) thefollowing eDuation5

" e; sw

here,

" -lter drag, N1minBm: " PBe e4trapolated clean -lter drag, N1minBm

s slope constant. aries with the dust, g

fabric, N1minB2g1m

Areal dust densit) L t

L dust loading %gBm:', *elocit) %mBs'




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&stimate the $alues o' Kea% Ks'or the l

ra* moel+

,imesto%e ust loai%* , = 1-00 *.m3

/abri rea = 1-00 m2

ir o rate = 0-80 m3.mi%

Time (min) 5 10 15 20 25 30

Filter P (Pa) 330 490 550 600 640 700

$@UIP0$NTProblem



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"alulate the air $eloitir $eloit = 0-80 (m3.mi%).1-00 m2

= 0-80 m.mi%

etermi%e Kea% Ks*raphiall

Ke= JS> N1minBm:Ks= >.?G: N1minBg1m

= P. 412-5 612-5 687-5 750 800 875

: = ,t 4 8 12 16 20 24

$@UIP0$NT"olution



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P Total pressure drop

Pf Pressure drop due to the fabric

Pp Pressure drop due to the particulate la)er

Ps Pressure drop due to the bag house structure




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A/ANTA($"

er) high collection e&cienc)

The) can operate o*er a wide range of *olumetric The pressure drops are reasonabl) low +abric +ilter houses are modular, and can be pre1

at the factor)/I"A/ANTA($"

+abric +ilters reDuire a large Koor area. The fabric is damaged at high temperature. Ordinar) fabrics cannot handle corrosi*e gases. +abric +ilters cannot handle moist gas streams A fabric -ltration unit is a potential -re ha8ard




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Pf Pressure drop NBm6

Pp Pressure drop NBm6

/f /epth of -lter in the direction of Kow %m'

/p /epth of particulate la)er in the direction of Kow %m'

(as *iscosit) 2gBm1s

super-cial -ltering *elocit) mBminf, p Permeabilit) %-lter V particulate la)er m6'

G> on*ersion factor WBmin

@BA

@*olumetric gas Kow rate m:Bmin

Acloth area m6

$@UIP0$NT/ARCQ" $@UATION



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L /ust loading 2gBm:

t time of operation min

XL 7ul2 densit) of the particulate la)er 2gBm:

P Pf; Pp

+ilter /rag " PB

Areal dust densit) Lt

" 2=;26

$@UIP0$NT/U"T LAC$R



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&stimate the %et loth area 'or a shaer ba* housethat must lter 40


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"alulate total area a% %umber o' ompo%e%ts reuire-

= .

"alulate the area o' eah ba*-

= ? () l

"alulate the total %umber o' ba*s reuire-@umber o' ba*s reuire = Total area . rea per ba*

= 1270 ba*s

@umber o' ompartme%ts 4000 s- 't- . ompartme%t

@"olution



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Electrostatic Charging of Dust Particles Cutaway of Electrostatic Precipitator

@$L$TRO"TATI PR$IPITATORB$"P


"


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The particles in a polluted gas are charged b) passinthrough an electric -eld

The charged particles are led through collector plate The collector plates ha*e charges opposite to that on

particles

The particles are attracted to these plates and are thremo*ed from the gas steam

ON"TRUTIONBOP$RATION harging $lectrodes in the form of thin wires are plac

the path of the inKuent gas.

The charging electrodes generate a strong electric -which charges the particles as the) Kow through it.

The collector plates get deposited with the particles.particles are occasionall) remo*ed either b) rapping

$"P PRINIPL$


$"P PRINIPL$


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The e&cienc) of remo*al of particles b) an$lectrostatic Precipitator is gi*en b)

Y fractional collection efficienc)

w drift *elocit), mBmin.

A a*ailable collection area, m6

@ *olumetric Kow rate m:Bmin

$"P PRINIPL$


0I(RATION $LOITC


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here,

D charge %olumbus'

$p collection -eld intensit) %*oltsBm'

r particle radius %m'

d)namic *iscosit) of gas %Pa1"'

c unningham correction factor

0I(RATION $LOITC

UNNIN(!A0 ORR$TION +ATOR



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where,

T absolute temperature %Z2'

dp diameter of particle %m'

UNNIN(!A0 ORR$TION +ATOR


Problem


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% &P is esi*%e to treat 50


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&Bie% o' a% &letrostati Preipitator is *i$e% b

=EF (.)Gl%(1E H)I

A S>,>>> m6

@umber o' plates = total area.plate area =J>>

"olution

$L$TRO"TATI PR$IPITATORB$"P



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A/ANTA($"

er) high e&cienc), generall) of the order of .?1. "ince the $"Ps act on the particles and not on the air, thhandle higher loads with lower pressure drops.

The) can operate at higher temperatures. Operating costs are generall) low.

/I"A/ANTA($"

The initial capital costs are high. Although the) can be designed for a *ariet) of operating

conditions, the) are not *er) Ke4ible to changes in the oconditions, once installed.

Particulate with high resisti*it) ma) go uncollected.

$L$TRO"TATI PR$IPITATORB$"P

$T "RU77$R"



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Aeromix Wet Scrubber

$T"RU77$R"

$T "RU77$R"



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Floating Bed Wet Scrubber

$T"RU77$R"

$T "RU77$R"



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Principle et scrubbers are used for remo*al of particles which ha*e

diameter of the order of >.6 mm or higher. et scrubbers wor2 b) spra)ing a stream of -ne liDuid drop

on the incoming stream.

The droplets capture the particles The liDuid is subseDuentl) remo*ed for treatment.

onstructionBOperation

A wet scrubber consists of a rectangular or circular chambewhich no88les are mounted.

The no88les spra) a stream of droplets on the incoming gasstream

The droplets contact the particulate matter, and the particleget sorbed.

The droplet si8e has to be optimi8ed.

$T"RU77$R"

$T "RU77$R"



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%[ ONT/..'

"maller droplets pro*ide better cleaning, but are mdi&cult to remo*e from the cleaned stream.

The polluted spra) is collected. Particles are settled out or otherwise remo*ed from

liDuid.

The liDuid is rec)cled. et scrubbers are also used for the remo*al of gas

from the air streams

$T"RU77$R"

$T "RU77$R"



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$&cienc)

here.6 mmha*e been obtained.

$NTURI"RU77$R"



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bsolute Pressure rop

Np = pressure rop ( m o' ater)

O* = *as $eloit (m.s)

t = liui $olume o rate

* = *as $olume o rate


Problem


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:ater is i%troue i%to the throat o' a $e%turisrubber- The air $eloit throu*h the srubber is

550 'ps a% the liui to *as ratio is 8-5 *al.1000atual 't3- etermi%e the pressure rop

bsolute pressure rop is *i$e% b

p J.M


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!C/ROAR7ONONTROL

($N$RAL 0$T!O/"5 ININ$RATIONBA+T$R 7URN



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/irect Kame incineration

Thermal incineration atal)tic incineration


Problem


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"alulate the remo$al eBie% o' a bur%er i' theo%e%tratio% o' Q" as reue 'rom 1300 ppm to

!emo$al &Bie% o' the bur%er

$&cienc) %initial concentration < -nalconcentration'B initial concentration

&Bie% o' the bur%er = 92-3A

OININ$RATOR"



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OININ$RATOR"



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Principle O incinerators thermall) o4idi8e the

e\uent stream, in the presence of e4cess air.

The complete o4idation of the O results inthe formation of carbon mono4ide and water.

The reaction proceeds as follows5

4!) ; % 4 ; )BJ ' O61] O6 ; %)B6'

!6O

Operation

The most important parameters in the design

and operation of an incineration s)stem are

h ll d h

O ININ$RATOR"5 T!R$$ _T`s


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Temperature

The reaction 2inetics are *er) sensiti*e to temperatu

The higher the temperature, the faster the reaction

Timing

A certain time has to be pro*ided for the reaction to

Turbulence

Turbulence promotes mi4ing between the O^s and Proper mi4ing helps the reaction to proceed to comp

the gi*en time.

OININ$RATOR"


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OININ$RATOR"


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OININ$RATOR"


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The *arious methods for incineration are5 $le*ated -res, for concentrated streams /irect thermal o4idation, for dilute streams atal)tic o4idation, for dilute streams.

Problem


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R% a orshop a mi>ture o' hemials ere releaseture

VmE olume o' mi>ture

,&,iE ,&, o' i ompo%e%t

,&,mi>= F3000.(6000G1-4) # 1000.(6000G1-27) # 2000.

(6000G5)IE1

= 1-79A


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(A"$"BAPOUR"ONTROL

(A"$"ONTROL



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The most common method for controlling gaseous pis the addition of add1on control de*ices to reco*er o

a pollutant.

There are four commonl) used control technologies gaseous pollutants5

Absorption,

Adsorption,

ondensation, and

Incineration %combustion'

Th l f

A7"ORPTION



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The remo*al of one or moreselected components b)absorption is probabl) the

most important operation inthe control of gaseouspollutant emissions.

Absorption is a process inwhich a gaseous pollutant isdissol*ed in a liDuid.

ater is the most commonl)used absorbent liDuid.

As the gas stream passesthrough the liDuid, the liDuidabsorbs the gas, in much thesame wa) that sugar is

Typical Packed Diagram

A7"ORPTION



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Absorbers are often referred to as scrubbers, andthere are *arious 2inds of absorption eDuipment.

The main t)pes of gas absorption eDuipmentinclude spra) towers, pac2ed columns, spra)chambers, and *enture scrubbers.

In general, remo*al e&ciencies are grater than ?. One potential problem with absorption is thegeneration of waste1water, which con*erts an airpollution problem to a water pollution problem.

A/"ORPTION



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hen a gas or *apor is brought into contactwith a solid, part of it is ta2en up b) the solid.The molecules that disappear from the gaseither enter the inside of the solid, or remainon the outside attached to the surface. Theformer is termed absorption %or dissolution'and the latter adsorption.

ommon industrial adsorbents are acti*atedcarbon, silica gel, and alumina, because the)ha*e enormous surface areas per unit weight.

Acti*ated carbon is the uni*ersal standard forpuri-cation and remo*al of trace organiccontaminants from liDuid and *apor streams.

arbon adsorption s)stems are either regenerati*e

A/"ORPTION



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arbon adsorption s)stems are either regenerati*e regenerati*e.

Regenerati*e s)stem usuall) contains more than

carbon bed. As one bed acti*el) remo*es pollutaanother bed is being regenerated for future use.

Non1regenerati*e s)stems ha*e thinner beds of acarbon. In a non1regenerati*e adsorber, the spenis disposed of when it becomes saturated with thpollutant.

Non-RegenerativeCarbon Adsorption

System

Regenerative CarbonAdsorption System

A/"ORPTIONTO$R"



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ON"TRUTIONBOP$RATION

Adsorption towers consist of c)linders pac2ed with the The adsorbent is supported on a hea*) screen "ince adsorption is temperature dependent, the Kue ga

temperature conditioned.

apor monitors are pro*ided to detect for large concentthe e\uent. Large concentrations of the pollutant in thindicate that the adsorbent needs to be regenerated.

A/ANTA($"

er) low concentrations of pollutants can be remo*ed. $nerg) consumption is low. /o not need much maintenance. $conomicall) *aluable material can be reco*ered during

regeneration-

ON/$N"ATION



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It is the process of con*erting a gas or *apor to liDAn) gas can be reduced to a liDuid b) loweringtemperature andBor increasing its pressure.

The) are t)picall) considered as pretreatment de*iThe) can be used ahead of absorbers, absorbers, incinerators to reduce the total gas *olume totreated b) more e4pensi*e control eDuipment.

ondensers used for pollution control are concondensers and surface condensers.

ON/$N"ATION



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ontact condenser, the gascomes into contact with coldliDuid.

In a surfacecondenser, thegas contacts a cooled surfacein which cooled liDuid or gasis circulated, such as theoutside of the tube.

Remo*al e&cienciesrange

from ?>to more than ?,depending on design andapplications.

!urace condenser

Contact condenser

95

I i i l 2 b i i

ININ$RATION



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Incineration, also 2nown as combustion, is mosto control the emissions of organic compoundsprocess industries.

This control techniDue refers to the rapid o4idaa substance through the combination of o4)gea combustible material in the presence of heat

hen combustion is complete, the gaseous strcon*erted to carbon dio4ide and water *apor.

$Duipment used to control waste gases b)combustion can be di*ided in three categories5

/irect combustion or Karing, Thermal incineration and atal)tic incineration.

/IR$TO07U"TOR



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In/irect combustor air and all the combustiwaste gases react at the burner. omplete

combustion must occur instantaneousl) sincthere is no residence chamber.

A Karecan be used to control almost an) emstream containing *olatile organic compounThe e&cienc) of a Kare is about M .

In thermal incinerators the combustible

T!$R0ALININ$RATOR"



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In thermal incinerators the combustiblewaste gases pass o*er or around a burnerKame into a residence chamber where

o4idation of the pollutant gases iscompleted.

The e&ciencies are of the order .

Thermal incinerator general case

atal)tic incinerators are *er) similar toATALCTIININ$RATOR"



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thermal incinerators. The main diEerence isthat after passing through the Kame area,the gases pass o*er a catal)st bed.

A catal)st promotes o4idation at lowertemperatures, thereb) reducing fuel costs.$&ciencies are greater than ? .


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455

IR@UALITC 0O/$LLIN(

0O/$LLIN(

AI


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Air @ualit) 0odels are mathematicalformulations that include parameters that

aEect pollutant concentrations.

The) are used to

$*aluate compliance with NAA@"and othregulator) reDuirements

/etermine e4tent of emission reductionsreDuired

$*aluate sources in permit applications

454

0O/$LLIN(TCP$"

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!ource

"ispersion

Model

eceptor

Model

%mission

Model

Meteorological

Model

Chemical

ModelTe"poral and spatial e"ission rates

Topograph!

Che"ical Transfor"ation

Pollutant Transport

E7uilibriu" bet#een Particles and gasesVertical 8i-ing

0O/$LLIN( TCP$"AI


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$mission 0odel &stimates temporal a% spatial emissio% rates bas

ati$it le$el< emissio% rate per u%it o' ati$itmeteorolo*

0eteorological 0odel esribes tra%sport< ispersio%< $ertial mi>i%*

moisture i% time a% spae

hemical 0odel esribes tra%s'ormatio% o' iretl emitte pa

a% *ases to seo%ar partiles a% *ases;estimates the euilibrium betee% *as a% parti$olatile speies

0O/$LLIN( TCP$"AI


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"ource /ispersion 0odel Oses the outputs 'rom the pre$ious moels

estimate o%e%tratio%s measure at reeptoi%lues mathematial simulatio%s o' tra%spoispersio%< $ertial mi>i%*< epositio% ahemial moels to represe%t tra%s'ormatio%-

Receptor 0odel R%'ers o%tributio%s 'rom iCere%t primar sou

emissio%s or preursors 'rom multi$arimeasureme%ts tae% at o%e ore more reepsites-

456

0O/$LLIN(LA""I+IATIONAI


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e$elope 'or a %umber o' polluta%t tpetime perios

"hort1termmoels 'or a 'e hours to a 'eorst ase episoe o%itio%s

Long1term moels to preit seaso%al or a$era*e o%e%tratio%s; health eCets e>posure

"lassie b Non1reacti*e moels polluta%ts suh as

"W

Reacti*emoels polluta%ts suh as W3< @W2< 457

"lassie b oori%ate sstem

0O/$LLIN(TCP$"AI


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"lassie b oori%ate sstemuse

(rid1based !e*io% i$ie i%to a% arra o' ells

Ose to etermi%e omplia%e ith@

Traector) /ollo plume as it mo$es o%i%

"lassie b le$el o'sophistiatio%

"creening+ simple estimatio% usepreset< orstEase meteorolo*ialo%itio%s to pro$ie o%ser$ati$e 458

The cit) of interest is assumed to be

+IH$/17OH0O/$L"AI


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459

rectangular.

The goal is to compute the air pollutan

concentration in this cit) using the generamaterial balance eDuation.

= Rectangular cit) and L are the dimension

+IH$/17OH 0O/$L"5 A""U0PTION"AI


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45:

=. Rectangular cit). and L are the dimensionone side parallel to the wind direction.

6. omplete mi4ing of pollutants up to the height !. No mi4ing abo*e this height.

:. The pollutant concentration is uniform in the*olume of air o*er the cit) %concentrations upwind and downwind edges of the cit) asame'.

J. The wind blows in the 4 direction with *elocwhich is constant and independent of location, V ele*ation.

? The concentration of pollutant in the air enteri

+IH$/17OH 0O/$L"5 A""U0PTION"AI


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45;

?. The concentration of pollutant in the air enteri

cit) is constant and is eDual to b%for bac2grou

concentration'.

G. The air pollutant emission rate of the cit) is Q

The emission rate per unit area is q Q!A %gBs.

is the area of the cit) % 4 L'. This emission raassumed constant.

S. No destruction rate %pollutant is su&cientl) lon

li*ed'


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> %all Kow rates in' %all Kow rates

IH$/17OH 0O/$L"5 ($N$RAL 0AT$RIAL 7ALANAI


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444

The eDuation indicates that the upwind concen

is added to the concentrations produced b) the To -nd the worst case, )ou will need to 2now th

speed, wind direction, mi4ing height, and upwi%bac2ground' concentration that corresponds tworst case.

> %all Kow rates in' < %all Kow ratesout'

" u # $ b % q # & ' u # $ c

here c is the concentration in the

entire cit)

uH

qLbc +=

it has the 'olloi%* esriptio%+ W= 5 m< Lu = 3 m.s Q = 1000 m The upi% or ba

Problem


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44#

u = 3 m.s< Q = 1000 m- The upi%< or bao%e%tratio% o' "W is b= 5 *.m3- The emissio

u%it area is q= 4 > 10E6

*.s-m2

- hat is the o%co' "W o$er the it

= 25 *.m3

uH

qLbc +=

( )

( )( )m!"""m#s$

m!%"""

m&s

g!"'

mg%

(

)

$

+=

c

+IH$/17OH 0O/$L"5 O00$NT"

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44+

The -4ed1bo4 models does not distinguishbetween area sourcesandpoint sources.

7oth sources are combined in the q *alue. e2now that raising the release point of thepollutant will decrease the ground1le*elconcentration.

The -4ed1bo4 models predict concentrations fonl) one speci-c meteorological condition, buthat conditions *ar) o*er the )ear.

=' !anna %=S=' suggested a modi-cation

+IH$/17OH 0O/$L"5 O00$NT"

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446

=' !anna %=S=' suggested a modi-cationallows one to di*ide the cit) into subarea

appl) a diEerent *alue of q to each. *ariation of qfrom place to place can be obtq is low in suburbs and much higher in indareas'.

6' hanges in meteorological conditions c

ta2en into account b)

a. determine the freDuenc) distributi*arious *alues of wind direction, u, and o

b. ompute the concentration for each

c& 0ultipl) the concentrations obtained in

+IH$/17OH 0O/$L"5 O00$NT"

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447

b b) the freDuenc) and sum to -nannual a*erage

=

iesmeteorologallo*ermeteoro

occurrence

fre+uenc

ymeteorolog

for that

ionconcentrat

ionConcentrat

A*erage

Annual

/or the it i% e>ample 6-1< the meteorolo*io%itio%s esribe (u = 3 m.s< H = 1000 m

Problem


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448

o%itio%s esribe (u 3 m.s< H 1000 mour 40 pere%t o' the time- /or the remai%i

60 pere%t< the i% blos at ri*ht a%*les the iretio% sho% i% /i*- 6-1 at $eloit 6 ma% the same mi>i%* hei*ht- :hat is the a%%ua$era*e o%e%tratio% o' arbo% mo%o>ie this it

/irst e %ee to ompute the o%e%tratioresulti%* 'rom eah meteorolo*ial o%itia% the% ompute the ei*hte a$era*e-

/or u= 3 m.s a% H= 1000 m X c= 25 *.m3

For u, ) m#s and H, !""" m -

(

( ) (

(

)

$ m!"""m#s)

%""m&s

g!"'

m

g%

+=

c

"olution


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449

$$$

iesmeteorologallo*er

m

g!%"&)

m

g.&$$"&'

m

g(%

ionConcentrat

A*erage

Annual

meteorolog

ofoccurrence

ofre+uency

ymeteorolog

for that

ionconcentrat

ionConcentrat

A*erage

Annual

=+=

=

( ) (

$

m

g.&$$

=c

Plume spread and shape *ar) in response tol i l di i

(UA""IAN PLU0$ 0O/$L"

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44:

meteorological conditions


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H

=u

3


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The general eDuation to calculate the stead) stat


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y

4#4

:here;

(>


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4##

$4planation5

? +or a clear V hot summer morning with lo

speed, the sun heats the ground and the heats the air near it. Therefore air rises andpollutants well.

Unstable atmosphere and large )V 8*alu

? On a cloudless winter night, ground coradiation to outer space and therefore coair near it. !ence, air forms an in*ersion la)

"table atmosphere and inhibiting the disof pollutants and therefore small )V 8*a

Table 3E1 :ar

(UA""IAN PLU0$ 0O/$L"5 "TA7ILITC LA""$"

AI


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Table 3 1 :ar

Documents

Air Pollution (QA)