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POLLUTION CONTROL IN

REFINERIES & PETROCHEMICALUNITS

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INTRODUCTIONPOLLUTION ROUTES

Crude oil production & Transportation-

Oil spillages

Pollution while processing

Thermal pollution of water bodies.

PROCESS LIQUIDWASTES

Distillation NH3, H2S,phenols

Desalting NaCl,phenols,H2S

VaccumDistillation

Phenol & Oil

Naphthahydrotreating

Sourcondensate

CatalyticHydrotreatin

g

H2S,Phenols,

Cyanides

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CHARACTERISTICS OF LIQUIDEFFLUENTS

Waste Concentration

Free oil 2000-3000mg/l

H2S & Sulphides 10-220 mg/l

Phenols 12-30 mg/l

Suspended Solids 200-400 mg/l

5 Day BOD at 20dgC 100-300 mg/l

Alkalinity 10-250 mg/l

In a n average refinery

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In a petrochemical industry

waste Concentration

pH 5.5-9.0

Suspended solids 100 mg/l

Dissolved O2 5 mg/l

BOD 100 mg/l

COD 250 mg/lPhenolic compounds 1 mg/l

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TREATMENT METHODS INPLANT MEASURES

STEAM STRIPPING

OXIDATION

REMOVAL OF PHENOLS

BIOLOGICAL TREATMENT DISPOSAL OF SLUDGES

LIQUID EFFLUENT TREATMENT

AIR POLLUTION CONTROL

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INPLANT MEASURESProper maintenance of pumps to prevent

water leakages

Isolation of oil-water emulsion stream andseparation by air flotation->COD 60-80%

Rectangular separator-Gravity settling

use Tilted plate separator

Oil droplets impinge , coalesce, & collecton top.

Acids & Coalesce aiding membrane structures

Good house kee in

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Tilted plate separator

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Corrugated plate interceptor

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Corrugated plate rack

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Steam strippingDuring catalytic reduction & distillation->sour

water containing NH3 , H2S & mercapton are formed

To remove this sour water strippers are used.

Physico- chemical & biological treatment isused

Air stripping at higher pH NH3.OxidationNH3 water & N2Sulphides thiosulphatesAir as an oxidizing agent

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Removal of phenolsA multistage modified activated sludge

process

Adsorption of phenol on activated charcoalBiological oxidation if specially cultured

microrganisms & optimum conditions exist

Solvent extraction->to recover phenols fromcaustic cresylates.

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BIOLOGICAL TREATMENTTrickling filters

Multistage activated sludge

Oxidation ponds

Aerated lagoons

Anaerobic digestion

Ferrobiological process

UNOX process

Maximum efficiencies for biological treatment-

>(80-95)%

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Oxidation pond

SOUR TASTE

WATERSTRIPP

ER

STORMWATER

PROCESS

WATERSEWE

RBASI

NAPISEPARATO

R

RETENTIONPOND OXIDATION

PONDLAGOO

N

ACID/ALKALINEUTRALIZEDWATER

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Oxidation ponds

Used for the treatment of integral effluents

Removal of oil, sulphides, phenols, BOD,

suspended solids.Includes API separator, chemical treatment, &

clariflocculator.

Coke-bed separator->removal of fine carbonparticles.

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Sludge disposalOil Sludge Chemical

SludgeBiological

Sludge

Formation Oil water

separations,precipitation

Chemical &

Oilprocessing

Biological

Oxidation

Processing Thickeningby gravity,centrifugation, filtration

Chemicalrecovery,cementmanufacture,land fills,

drained.

Anaerobicdigestion forbiogasproduction

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Treatment of effluentsfrom petrochemicals Process similar to refinery

For chemical recovery

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Air pollution

Air pollutants-H2S, NH3, SO2, NOx,mercaptons.

1)CONTROL OF SULPHUR DIOXIDE Recovered to meet shortage & pollution

control.

Acceptable range-50-500 ppm

Processes most commonly used & feasible

Cat-OX=>SO->catalyst->SO3->Sulphuric acid

Cal-OX=>SO2->Scrubbed with alkalinesolution ->lime re eneration

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B) REMOVAL OF H2S

Regenerative

H2S conc is high

CO2 is present

Scrubbed at low T with an alkaline solution inpacked plate units

Nonregenerative

H2S conc is low

Sulphur recovery isnot economical.

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Processes for removal of

H2SEthyl Amine Proces

Monoethyl amine-Highest capacity,

combines with CO2Diethyl amine- meets most requirements

triethyl amine -

-is used for absorption of H2S, CO2.Absorption efficiency->high at lower temp.

Phosphate process

Dilute potassium phosphate soln as scrubber

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K3PO4+H2S K2HPO4+KHS

Chemicals- nonvolatile & stable

ADSORPTION

By activated carbon, alumina, zeolite, bauxite

or iron oxideSpent adsorbant regenerated by roasting in

air.

OTHER PROCESSES

Thylox

Arsenite arsenate

Iron cyanide

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REMOVAL OF AMMONIA

Absorption by dilute sulphuric acid

Oxidation to NO2->absorption in water-

>HNO3REMOVAL OF PARTICULATES, NOX& HYDROCARBONS

A). PARTICULATESCyclone seperators

Scrubbers

Filters

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B).Nox

Less air, 2 stage combustion, recirculate partof flue gas

C).HYDROCARBONS

Cooling & adsorption

Disposed of by catalytic or non catalytic

combustion

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THANK YOU