II.stack Monitoring Gaseous Pollutants

39
COURSE MODULE ON STATIONARY SOURCE SAMPLING AND ANALYTICAL METHODS FOR GASEOUS POLLUTANTS FOR INDUSTRIAL POLLUTION PREVENTION AND CONTROL (IPPC) DR. AMBEDKAR INSTITUTE OF PRODUCTIVITY MADRAS PREPARED BY V.S.S.Bhaskara Murty Director (Environment) Dr Ambedkar Institute of Productivity National Productivity Council, Chennai 1995 1.0 INTRODUCTION

Transcript of II.stack Monitoring Gaseous Pollutants

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COURSE MODULE ON

STATIONARY SOURCE SAMPLING AND ANALYTICAL METHODS

FOR GASEOUS POLLUTANTS

FOR

INDUSTRIAL POLLUTION PREVENTION AND CONTROL (IPPC)

DR. AMBEDKAR INSTITUTE OF PRODUCTIVITY

MADRAS

PREPARED BY

V.S.S.Bhaskara Murty Director (Environment)

Dr Ambedkar Institute of Productivity National Productivity Council, Chennai

1995

1.0 INTRODUCTION

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Many industrial processes, such as Smelters, Fertiliser plants

fossil fuel combustions etc. emits gaseous air pollutant. The gas

sampling method constitutes the collection of representative gas

sample from the parent gas stream in a suitable absorbing media

and analysing the grab samples by wet chemical analysis.

The representative gas samples are collected through the sampling

port from any point across the cross section of the duct since

the gas composition is uniform. However proportional sampling

techniques have to be implemented if the source is unsteady and

vary with time.

Most frequently measured gas components viz. sulfur dioxide

(SO2), sulfur trioxide (SO3), acid mist, Nitrogen Oxides NOx) are

described below.

2.0 SULFUR DIOXIDE AND SULFUR TRIOXIDE

CPCB has prescribed emission standards for SO2 and SO3 for

different industrial operations as given in the Annexure-1. For

sulfuric acid manufacture these two gas components are analysed

combinedly interms of SO2 and in addition acid mist concentration

is another important parameter. The emission load of SO2 has

importance in calculating the minimum stack height requirements

of industrial operations.

2.1 PRINCIPLE AND APPLICABILITY

The basic problem is to detect SO2 in the presence of SO3 and

H2SO4. Therefore the latter components first must be removed

from the sample. The sulfur dioxide is then absorbed in a

hydrogen peroxide solution and eventually is determined

quantitatively by titration with barium perchlorate or barium

chloride. Thorin is used as a color indicator for this

titration.

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2.2 INTERFERENCES

Metal sulfates, phosphates, sulfuric acid mist, and cations which

complex with the thorin indicator or coprecipitate with barium,

interfere but can be eliminated by proper use of a filter.

2.3 SAMPLING TRAIN

The sampling train is similar to that of particulate sampling as

shown in Fig-1 except for the dust collecting thimble holder

which is replaced by a set of midget impingers for the absorption

of the gaseous components.

2.3.1 Sampling probe: A short sampling probe Pyrex or quartz is

used to prevent condensation prior to sample collection. Quartz

of Pyrex glass wool is placed in the entry of the probe to

prevent particulate matter from entering the scrubbers.

Alternatively a midget bubbler stuffed with glass wool is placed

at the end of the sampling probe along with the gas absorption

equipment. The particulate matter contains sulfates and also

other impurities which may precipitate with barium or complex

with the thorin indicator. Acid mist is also removed at this

point.

2.3.2 Absorption equipment: The sample collector consists of

three midget impingers (Fig-2) placed in an ice bath. The first

midget impinger contains 100 ml of 80% isopropyl alcohol

solution. This removes the SO3 and any carry over H2SO4 from the

filter. Some glass wool is placed at the top of the midget

bubbler to act as a filter and thus preventing any H2SO4 mist

from carrying over into the following midget impingers. The gas

stream becomes saturated with the isopropyl alcohol vapor, which

inhibits the oxidation of SO2 to SO3 because the alcohol is more

readily oxidized.

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The SO2 is removed in the next two midget impingers, which

contain 100 ml each of hydrogen peroxide solutions. SO2 is

absorbed in the impingers and converted to form H2SO4.

2.3.3 Flow metering: Finally the gases are passed through silica

gel drying column to protect the Dry Gas Meter which follow it.

To achieve the optimum absorption efficiency, the sampling flow

rate has to be set at a minimum constant flow rate of 2 lpm with

the help of rota meter and the needle valve.

2.3.4 Vacuum pump: Since the sampling flow rates are very low

the pressure drop across the sampling train is around 10 to 15

mmHg and hence a small capacity vacuum pump is enough for such

purpose.

2.4 GLASSWARE & REAGENTS

The following reagents and glass ware have to be kept ready in

the laboratory for analysis of the field samples.

2.4.1 Glassware: - Glass wash bottle to hold the deionized water - Polyethylene storage bottles for storing impinger samples prior to analysis. - Transfer pipettes: 5 ml and 10 ml sizes with 0.1 ml divisions and 25 ml size with 0.2 ml divisions - Volumetric flasks : 50 ml, 100 ml and 1000 ml - Burettes : 5 ml and 50 ml - Erlenmeyer flask : 125 ml - Dropping bottle for indicator solution.

2.4.2 Reagents:

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2.4.3 deionized distilled water

2.4.4 Hydrogen peroxide,(3% solution): Prepare by diluting 100

ml of 30% hydrogen peroxide to 1 liter with deionized water.

Caution: the 30% H2O2 is a strong skin irritant which is not

noticeable until a few minutes after the injury occurs. This

solution must be prepared daily.

2.4.5 Isopropyl alcohol,(80% solution): Prepare by mixing 80 ml

of isopropyl alcohol with 20 ml of deionized water. This

solution is stable.

2.4.6 Thorin indicator: [1-(0-arsonophenylazo) -2-naphthol-3,

6-disulfonic acid, disodium salt (or equivalent)]. Prepare by

dissolving 0.2 grams in 100 ml of deionized distilled water. It

should be stored in a polyethylene container since it tends to

deteriorate if stored in glass.

2.4.7 Barium perchlorate (0.01N): Prepare by dissolving 1.95

grams of barium perchlorate, Ba(ClO4)2 3H2O in 200 ml of

deionized water. Then dilute to 1 liter using isopropyl alcohol.

Alternatively, dissolve 1.22 grams of barium chloride,

BaC12.2H2O, in 200 ml deionized water and then dilute to 1 liter

with the isopropyl alcohol. The normality of this solution

should be standardized with standard sulfuric acid.

2.4.8 Sulfuric acid standard (0.01N): Purchase or standardize

to + or - 0.0002 N against 0.01 NaOH which has previously been

standardized against primary standard grade potassium acid

phthalate.

2.5 SAMPLING PROCEDURE

This method determines only the concentration in the gas stream.

The volumetric flow rate of the stack must be determined

according to EPA methods 1 and 2. The same sampling port which is

used for the velocity monitoring can be used for the gaseous

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sampling. Eventhough the gas composition is uniform across the

cross section of the duct, it is advised to collect the sample at

the centroid of the duct or not closer than 200mm to the duct

wall.

The sampling train is assemble as shown in the Fig-1 and leak

tested by plugging the probe inlet and pulling 300mmHg vacuum.

Observing the dry gas meter, the leakage rate should not exceed

1% of the desired sampling rate. If the leakage is severe, each

joint of the train should be inspected and the leak test

performed again. A thin film of silicone grease often helps to

make the joints leak tight.

The impingers are filled with the reagents as given in 5.2. The

initial reading of the DGM is recorded and a sampling flow rate

of 2 lpm is maintained at the rotameter. In case of unsteady

source conditions, " proportionate sampling" is implemented by

introducing the Pitot tube in to the duct along with the sampling

probe and the sampling flow rate varies with the variations in

the velocity of the gas stream. Gas samples are collected for a

minimum period of 20 to 30 minutes and the final DGM reading,

meter temperature and pressure are recorded.

At the end of the sampling disconnect the sampling probe from

impingers and flush the impingers with about 10 litres of

atmospheric air by turning on the vacuum pump. It is necessary to

transfer the entrapped SO2 in the first impinger and absorbed in

the following impingers. Transfer the contents of the impingers

into the polythene bottles and continue sampling for next set of

samples. A minimum of two samples have to be collected to get

consistent and representative data.

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2.6 ANALYTICAL PROCEDURES

2.6.1 Sulfur Trioxide (SO3): Transfer the sample from the first

impinger to a 100ml volumetric flask and make up to the mark with

distilled, deionized water. SO3 is absorbed by water and forms

H2SO4. Pipette a 10 ml aliquot to a 125-ml Erlenmeyer flask and

add 40 ml of isopropanol and 2 to 4 drops of the Thorin indicator

solution. The solution will then have a yellow-orange color.

The sulfuric acid is titrated against standardized barium usually

as the perchlorate or chloride. Thorin is used, which acts to

complex, and excess barium is added, thus giving a color

indicator. Titrate to a pink end point with the 0.01 N barium

perchlorate and record results.

During the titration the barium is consumed by the sulfate and

forms, in the presence of isopropyl alcohol, a gelatinous type of

precipitate which equilibrates rapidly. At the first presence of

any excess barium, a pink barium-thorin complex forms indicating

that all of the sulfate has been consumed. The determination of

the end point by the color change may take some practice on the

part of the analyst; it is less vivid than some other

calorimetric indicators but nonetheless proves to be quite

adequate.

The standard laboratory procedure of using a blank of deionized

water should be used for all sets of samples, allowing any

systematic error due to the reagents or procedures to be

accounted for.

2.6.2 Sulfur Dioxide (SO2): Transfer the samples from the two

midget impingers in to two 100ml volumetric flasks separately and

make up to the mark with distilled water. The SO2 has been

oxidized to SO3 with H2O2 and hydrolyzed to form sulfuric acid in

the impingers. Follow the same analytical procedure as given in

2.6.1 for the samples in both the impingers separately to check

the absorption efficiency and to ensure that there is no escape

of SO2 along with the gas.

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2.7 DATA ANALYSIS

2.7.1 Volume of the gas sampled: The difference of the initial

and final readings of DGM gives the gas volume sampled at meter

temperature (Tm) and Pressure (Pm) conditions. This can be

further converted to normal conditions as

Tn x Pm Qn = Qm --------- . . . (1) Tm x Pn Where Qn .. Volume of gas sample under normal condition, NM3 Qm .. Volume of gas sample under meter conditions, M3 Tn .. The absolute gas temperature at normal conditions,298 oK Tm .. The absolute dry gas meter temperature, oK Pn .. The absolute pressure at normal conditions, 760 mmHg Pm .. The absolute pressure at the gas meter, mmHg 2.7.2 SO3 concentration:

The concentration of SO3 in the gases is determined using the

following expression:

(A-B) x V x N x 40 CSO , mg/NM3 = ----------------------- . . . (2) 3 v x Qn

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Where A .. Volume of the Ba(ClO4)2 consumed by the sample aliquot,ml B .. Volume of the Ba(ClO4)2 consumed by the blank,ml v .. Volume of the aliquot,ml V .. Volume of the absorbing solution,ml N .. Normality of Ba(ClO4)2 48 .. Equivalent weight of SO3, gm/gm mole 2.7.3 SO2 concentration:

The concentration of SO2 in the gases is determined using the

same expression for SO3 by replacing the equivalent weight with

36 gm/gm mole. The average concentration of SO2 is estimated by

considering the arithmetic average of both the impinger readings.

2.8.0 SUMMARY

Laboratory analysis is completely wet chemical and several

hazardous solutions are used. For example extreme care must be

used when working with the 30% hydrogen peroxide solution. This

strong oxidant is a harsh skin irritant, the effect of which is

unnoticed until about 5 minutes after exposure.

3.0 ACID MIST CONCENTRATION

Acid mist from sulfuric acid plant emissions is sampled by

isokinetic sampling techniques using a glass fibre thimble since

the acid mist also persists in different droplet sizes. The

sampling train similar to particulate matter concentration

measurements is employed for acid mist sampling as shown in

Fig-3.

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For analysis the thimble is thoroughly washed with distilled

water and the resultant solution is titrated against Ba(ClO4)2 as

given in 2.6.1. The concentration of acid mist is calculated by

using the same (2) for SO3 estimation by replacing the equivalent

weight by 49 gm/gm mole.

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4.0 NITROGEN OXIDES (NOx)

Nitrogen oxides mainly consisting nitrogen dioxide (NO2) and

nitrous oxide (NO) forms by the combustion reactions. Combustion

temperatures up to about 600oC NO2 formation is maximum. Normally

in industrial operations where the combustion temperatures are

about 1000oC, Nitrogen Oxides comprise of about 90-95% of NO and

remaining NO2. CPCB has prescribed standard procedure for

sampling and analysis of NOx based on the method EPA-7. However

CPCB has not yet prescribed any standards for the NOx emissions.

However NOx is a dominant pollutant in atmospheric reactions and

formation of secondary pollutants.

4.1 PRINCIPLE AND APPLICABILITY

The sample is removed by a grab sampling technique. It is

captured in a 1-litre grab pipette or a 1-litre evacuated flask

which contains an absorbing solution of hydrogen peroxide and

sulfuric acid which converts the NOx (except N2O) in the captured

gas to HNO3 in solution. The amount of nitrate in solution is

determined by the phenoldisulfonic acid method. The amount of

nitrate (NOx) is then determined by calorimetric comparison to

standard solutions of potassium nitrate.

4.2 INTERFERENCES

Phenoldisulfonic acid (PDS) forms a strong color complex with NOx

and no interferences are reported.

4.3.0 SAMPLING TRAIN

The sampling train for collection and analysis of NOx samples by

grab pipette is shown in Fig-4. Quartz or Pyrex wool is packed in

the glass probe to prevent particulate matter from entering the

flask. A vacuum pump draws the gas sample through the grab

pipette. The sampling flow rate is adjusted at 2 lpm by a needle

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valve so that there is excessive vacuum build up in the grab

pipette.

The method EPA-7 suggest evacuated flask method as shown in

Fig-5. The stopcocks and the T-bore insure the proper sequence

for evacuating, purging and sampling. A high capacity vacuum

pump pulls the vacuum in the flask up to a maximum of 70 mmHg

(absolute). The evacuated flask as a part of the sampling train

is connected to the source and with the help of the T-bore the

sample is drawn in to the flask. The accuracy of measurement

depends on the maximum vacuum created in the sample flasks. If

the vacuum pump has no enough capacity to draw the vacuum it is

suggested to use the grab pipette method which can produce the

results with acceptable range of error.

4.4.0 GLASSWARE, EQUIPMENT AND REAGENTS 4.4.1 Glassware - Beakers or casseroles, 250 ml - Volumetric pipettes, 1, 2 and 10 ml - Transfer pipette, 10 ml with 0.1 ml divisions - Volumetric flasks : 100 ml for each sample; 1000 ml for standard - Graduated cylinder, 100 ml with 1.0 ml divisions 4.4.2 Equipment - Steam bath - Spectrophotometer, measurement at 420 nm - Analytical balance, measure to 0.1 mg. 4.4.3 Reagents - Concentrated H2SO4 - 3% H2O2

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- Distilled water - 1 N NaOH solutions (add 40 g NaOH in distilled water and dilute to one liter) - Red litmus paper - Phenoldisulfonic acid (PDS) - Potassium nitrate

4.5.0 SAMPLING PROCEDURES

4.5.1 Laboratory procedure

The volume of the flask/grab pipette must be determined. This is

done by filling the flask/grab pipette with water and then

measuring the volume of water with a graduated cylinder. Record

the volume on each flask/grab pipette.

The absorbing solution is prepared by adding 2.8 ml of

concentrated H2SO4 to 1 liter of distilled water. To this mixed

solution, add 6 ml of 3% hydrogen peroxide. Fresh solution

should be prepared weekly and protected from heat or sunlight.

4.5.2 Field procedure

This method determines only the concentration in the gas stream.

The volumetric flow rate of the stack must be determined

according to EPA methods 1 and 2.

Three repetitions are required per test and two grab samples are

required per source. These two samples should be taken over a

two-hour interval, if the process characteristics are not known.

If the process is known to be steady, then the time can be

shortened. Clean justification of this modification should be

included in the final report.

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4.5.2.1 Grab pipette: Connect the grab pipette (Fig-4) to the

sampling probe and the vacuum pump through the rotameter and

needle valve. Set the sampling flow rate at 2 lpm. Insert the

sampling probe into the duct, open both the stop cocks of the

pipette and allow purging for about 5 minutes with the process

gas. Close the stop cocks at the out let of the pipette first and

the second one immediately so that there is no evacuation of the

gas from the pipette or the gas collection is under vacuum.

4.5.2.2 Sampling in evacuated flask: Pipette 25 ml of absorbing

solution into a sample flask. Insert the flask valve stopper

into the flask with the valve in the "purge" position. Assemble

the sampling train as shown in Fig-5 and place the probe at the

sampling point. Turn the flask valve and the pump valve to their

"evacuate" positions. Evacuate the flask to at least 70mmHg

absolute pressure. Turn the pump valve to its "vent" position

and turn off the pump. Check the manometer for any fluctuation

in the mercury level. If there is a visible change over the span

of one minute, check for leaks. Record the initial volume,

temperature, and barometric pressure. Turn the flask valve to its

"purge" position, and then do the same with the pump valve.

Purge the probe and the vacuum tube using the squeeze bulb. If

condensation occurs in the probe and flask valve area, heat the

probe and purge until the condensation disappears. Then turn the

pump valve to its "vent" position. Turn the flask valve to its

"sample" position and allow sample to enter the flask for about

15 seconds. After collecting the sample, turn the flask valve to

its "purge" position and disconnect the flask from the sampling

train. Shake the flask for 5 minutes.

4.6.0 Analytical procedure

4.6.1 Recovery: This method specifies a minimum sample

absorption time of 16 hours. Margolis and Driscolls

theoretically predicted a 97% recovery would require 28.7 hrs.

Hence the absorption process is the slowest step in the NOx

procedure. The samples may be returned to the laboratory in the

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flask/pipette and kept in a cool and dark place for a minimum

period of 24 hrs.

4.6.2 Analysis: After the absorption period shake the contents

of the flask/pipette for 2 minutes. The contents of the flask are

then transferred to 100 ml china dish. The flask/pipette is

rinsed with two small portions of distilled water (10 ml). An

accompanying blank of absorbing solution, along with an equal

amount of rinse, is also processed. Then 1.0 N NaOH is added to

the absorbing solutions until they are alkaline to litmus paper.

Evaporate the solution to dryness on a steam bath and then cool.

Add 2 ml phenoldisulfonic acid solution to the dried residue and

dissolve all the residue thoroughly using a glass rod. Make sure

the solution contacts all the residue. Add 1 ml distilled water

and 4 drops of concentrated sulfuric acid. Heat the solution on

a steam bath for 3 minutes with occasional stirring if any

undissolved matter presents. Cool, add 20 ml distilled water,

mix well by stirring, and add concentrated ammonium hydroxide

drop wise with constant stirring until alkaline to litmus paper.

Transfer the solution to a 100 ml volumetric flask and wash the

beaker three times with 4 to 5 ml portions of distilled water.

Dilute to the mark and mix thoroughly. If the sample contains

solids, transfer a portion of the solution to a clean, dry

centrifuge tube, and centrifuge, or filter a portion of the

solution. Measure the absorbance/extintion of each sample in a

spectro photometer at 420 nm using the blank solution as a zero.

Read the amount of NO2 value "m" correspond to the

absorbance/extintion value from the standard calibration grab

drawn following the procedure given in 4.6.3. Dilute the sample

and the blank with a suitable amount of distilled water if

absorbance falls outside the range of calibration.

4.6.3 Calibration

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The standard solution is prepared by dissolving 0.5495 g of KNO3

in distilled water and diluting to 1 liter. The working solution

is prepared by diluting a 10-ml portion of the standard solution

to 100 ml; 1 ml of this solution then is equivalent to 25 ug of

NO2. The calibration curve is prepared by adding 0.0 to 16.0 ml

of standard solution to a series of china dishes. To each dish

add 25 ml of absorbing solution and follow the same analytical

procedure given in 4.6.2. A calibration graph (Fig-6) is then

drawn in micro grams of NO2 per sample versus

absorbance/extintion at 420 nm.

4.7.0 DATA ANALYSIS

4.7.1 Sample gas volume in evacuated flask

The sample volume at normal conditions is calculated by the

following expression.

a) For Evacuated flask _ _ | | | Pf Pi | Tn Vn = (Vf-Va) x |----- - ---- | x -- | Tf Ti | Pn |_ _| b) For Grab pipette Ps x Tn Vn = (Vf-Va) x --------- Pn x Ta Where

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Vn .. Dry sample volume at normal conditions, ml Vf .. Volume of flask and valve, ml Va .. Volume of absorbing solution, 25 ml Pf .. Final absolute pressure of flask, mmHg Pi .. Initial absolute pressure of flask, mmHg Ps .. Absolute stack pressure, mmHg Ta .. Absolute ambient temperature, oK Tf .. Final absolute temperature of flask, oK Ti .. Initial absolute temperature in flask, oK

The calibration curve is used in conjunction with the following

expression to determine stack gas concentration. m x 1000 CNOx,mg/NM3 = ---------- Vn Where CNOx .. Concentration of NOx as NO2 (dry basis), mg/NM3 m .. Micro gram of NO2 from the calibration graph

4.8 SUMMARY

The NOx field test can be conducted easily by one person. In

fact this field test can be run at the same time as other

pollutant tests. Thus if a team of 2 or 3 people is conducting

an isokinetic particulate matter test, the NOx samples can be run

concurrently.

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The NOx laboratory procedure is lengthy, requires a number of

steps and analysis must be performed by a qualified chemist or

laboratory technician. Errors may arise due to improper

procedures and deterioration of reagents.

The velocity traverse must be run concurrently with this NOx

test. Also the pertinent process information for the sampling

period is essential. Remember, the NOx concentration data may

only be part of what is needed to determine compliance.

Regulations are sometimes stated on the basis of pounds per

million BTU's input or pounds per ton of process weight.

5.0 OTHER GASEOUS COMPONENTS

The sampling and analytical procedures for other frequently

encountered gases like Ammonia, Urea (dust), Fluorides are given

in Annexures 6 to 8.

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ANNEXURE -

DIFFERENT INDUSTRIAL EMISSION STANDARDS FOR

GASEOUS POLLUTANTS - PRESCRIBED BY CPCB ------------------------------------ 1. SULFURIC ACID MANUFACTURE ---------------------------------------------------------------- Process Sulphur dioxide Acid mist emission emission ----------------------------------------------------------------- Single conversion 10 Kg/tonne of 50 mg/Nm3 Single absorption concentrated (100%) acid produced Double conversion 4 Kg/tonne of 50 mg/Nm3 Double absorption concentrated (100%) acid produced. ---------------------------------------------------------------- 2.0 NITRIC ACID --------------------------------------------------------------- Standard for oxides of nitrogen, NOx 3Kg of Nox per tonne of weak acid (before concentration) produced. --------------------------------------------------------------- 3.0 OIL REFINERIES: ----------------------------------------------------------------- Process Emission Limit ----------------------------------------------------------------- Standard for sulphur dioxide Distillation 0.25 Kg/Te of feed* (Atmospheric Plus Vacuum) Catalytic Cracker 2.5 Kg/Te of feed Sulphur Recovery Unit 120 Kg/Te of Sulphur in the feed --------------------------------------------------------- * Feed indicates the feed for that part of the process under

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consideration only. 4.0 COKE OVEN ----------------------------------------------------------------- Standard for Carbon monoxide 3.0 kg/T of coke produced ----------------------------------------------------------------- 5.0 POWER GENERATION BOILERS ----------------------------------------------------------------- ----------------------------------------------------------------- Boiler size Stack height ----------------------------------------------------------------- Standard for Sulphur dioxide control (through stack height) Less than 200 MW H = 14 (Q) 0.3 200 MW to less than 500 MW 220 meters 500 MW and more 275 meters ----------------------------------------------------------------- Q = Sulphur Dioxide emission in kg/hr H = Stack height in meters 6.0 STACK HEIGHT FOR COAL FIRED BOILERS --------------------------------------------------------- Capacity of Steam generation Stack height --------------------------------------------------------- 1. Less than 2 tons/hour Two and a half times (or 2.6 MT/day of coal used) the neighboring building height of 9.0 m whichever is more 2. More than 2 tons/hr to 5 tons/ 12.0 m hour (or 2.6 MT/day to 6.5 MT/day of coal used) 3. More than 5 tons/hr to 10 tons/ 15.0 m hour (or 6.5 MT/day to 13 MT/ day of coal used)

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4. More than 10 tons/hr to 15 tons 18.0 m /hour(or 13 MT/day to 19.5 MT/day of coal used) ----------------------------------------------------------------- Contd .... --------------------------------------------------------- Capacity of Steam generation Stack height --------------------------------------------------------- 5. More than 15 tons/hr or 20 tons 21.0 m /hour (or 19.5 MT day to 26.0 MT/day of coal used) 6. More than 20 tons/hr to 24.0 m 25 tons/hour (or 26 MT/day of coal used) 7. More than 25 tons/hr to 30 27.0 m tons/hour (or 32.5 MT day 39 MT/day of coal used) 8. More than 30 tons/hour (or 30.0 m or using the than 39 MT/day of coal used) formula H=14) where H=minimum stack height required in metres. Q is sulfur dioxide emissions in kg/hr, whichever is more) --------------------------------------------------------

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ANNEXURE - 2

MODEL PROBLEM FOR SULFUR DIOXIDE AND SULFUR TRIOXIDE ANALYSIS AND ESTIMATION

------------------------------------------------------------ 1.0 A Fertiliser plant has a 100 TPD sulfuric acid plant producing concentrated sulfuric acid (98%) through DCDA process. Source emission monitoring was conducted at the stack located at the end of the second absorption column. The flow rate of the gases was measured to be 12,500 NM3/hr at 52oC following the EPA standards methods 1 to 4. 1.1 Sulfur trioxide and sulfur dioxide samples were collected and analysed by EPA standard method 6. The data collected are as follows: Volume of the gas sample collected = 50 lit DGM temperature = 35oC Vacuum at DGM = 14 mmHg Volume of the absorption media for SO3 estimation = 98 ml Volume of the absorption media for SO2 estimation = 192 ml Volume of the aliquot for both SO2 & SO3 analysis = 20 ml Ba(ClO4)2 consumption by SO2 aliquot = 9.8 ml Ba(ClO4)2 consumption by SO3 aliquot = 3.5 ml Ba(ClO4)2 consumption by blank = 1.2 ml Ba(ClO4)2 normality = 0.00987N Atmospheric pressure = 740 mmHg Calculate the concentrations of SO2 and SO3 in the emissions and also check whether the emissions comply with emission regulations.

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1.2 The acid mist sample in the emissions was also collected following the method EPA-8 and the collected data are as follows: Volume of the gas sample collected across the duct through isokinetic sampling = 345 lit DGM temperature = 35oC Average vacuum recorded in the DGM = 18 mmHg Volume of the sample after thible wash = 250 ml Volume of the aliquot for analysis = 50 ml Ba(ClO4)2 consumption by the aliquot = 4.6ml Ba(ClO4)2 consumption by blank = 1.2 ml Ba(ClO4)2 normality = 0.00987N Calculate the concentrations of acid mist in the emissions and also check whether the emissions comply with emission regulations. 2.0 SOLUTIONS: 2.1 Estimation of SO3 Volume of the gas sample collected = 50 lit Under normal conditions, Qn 0.05 x 726 x 298 Qn = ----------------- = 0.046 NM3 760 x 308 Concentration of sulfur trioxide is calculated by (A-B) x V x N x 40 CSO , mg/NM3 = --------------------- . . . (2) 3 v x Qn

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Where A .. Volume of the Ba(ClO4)2 consumed by the sample aliquot,ml B .. Volume of the Ba(ClO4)2 consumed by the blank,ml v .. Volume of the aliquot,ml V .. Volume of the absorbing solution,ml N .. Normality of Ba(ClO4)2 48 .. Equivalent weight of SO3, gm/gm mole (3.5-1.2) x 98 x 0.00987 x 40 CSO , mg/NM3 = -------------------------------- 3 20 x 0.046 = 96.7 or 29.6 ppm SO3 emission load = SO3 conc. x emission flow rate = 96.7 mg/NM3 x 12,500 NM3/hr = 1.21 kg/Hr H2SO4 manufacture = 100 TPD (98%) = 98 TPD (100%) = 4.08 T/Hr 1.21 SO emission factor = ---- = 0.3 kg/T of 100% acid 3 4.08 2.2 Estimation of SO2 Concentration of sulfur dioxide is calculated by

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(A-B) x V x N x 32 CSO , mg/NM3 = --------------------- . . . (2) 2 v x Qn Where A .. Volume of the Ba(ClO4)2 consumed by the sample aliquot,ml B .. Volume of the Ba(ClO4)2 consumed by the blank,ml v .. Volume of the aliquot,ml V .. Volume of the absorbing solution,ml N .. Normality of Ba(ClO4)2 32 .. Equivalent weight of SO2, gm/gm mole (9.8-1.2) x 192 x 0.00987 x 32 CSO , mg/NM3 = -------------------------------- 2 20 x 0.046 = 567 or 434 ppm SO2 emission load = SO2 conc. x emission flow rate = 567 mg/NM3 x 12,500 NM3/hr = 7.09 kg/Hr 7.09 SO emission factor = ---- = 1.74 kg/T of 100% acid 2 4.08 SO2 emissions are satisfying the CPCB standards of 4kg of SO2 per T of 100% sulfuric acid produced. 2.3 Estimation of Acid mist

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Volume of the gas sample collected = 345 lit Under normal conditions, Qn 0.345 x 722 x 298 Qn = ----------------- = 0.317 NM3 760 x 308 Concentration of sulfuric acid mist is calculated by (A-B) x V x N x 48 C H SO mist, mg/NM3 = --------------------- 2 4 v x Qn Where A .. Volume of the Ba(ClO4)2 consumed by the sample aliquot,ml B .. Volume of the Ba(ClO4)2 consumed by the blank,ml v .. Volume of the aliquot,ml V .. Volume of the absorbing solution,ml N .. Normality of Ba(ClO4)2 48 .. Equivalent weight of H2SO4, gm/gm mole (4.6-1.2) x 250 x 0.00987 x 48 CSO , mg/NM3 = -------------------------------- 2 50 x 0.317 = 25.4

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ANNEXURE - 3

MODEL PROBLEM FOR NITROGEN OXIDES ANALYSIS AND ESTIMATION ------------------------------------------------------------ A) PROBLEM A source sampling test was conducted on a 200 KVA diesel generator set. The flue gas analysis reveals 13% - CO2, 1.0% - CO and 5% - O2. Flue gas temperature measured to be 370oC. The samples for nitrogen oxide analysis were collected in an evacuated flask. The collected samples were analysed by Phenol Disulfonic Acid method following the standard EPA - 7 method. The analysis data are as follows Volume of the evacuated flask,ml : 960 Absolute flask pressure before sampling,mmHg : 70 Absolute stack pressure,mmHg : 735 Atmospheric pressure,mmHg : 740 Ambient temperature,oC : 35 Volume of the absorbing solution,ml : 25 Dilution ratio : 1:2 Extintion reading : 0.348 Corresponding NO2 value from calibration graph, ug : 350 NO2 quantity considering dilution, ug : 700 Calculate the concentration of NOx in the DG set exhaust gases in mg/NM3. B) SOLUTION Concentration of the NOx using evacuated flask method and with the given data can be calculated by using the following equation

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_ _ | | | Pf Pi | Tn Vn = (Vf-Va) x |----- - ---- | x -- | Tf Ti | Pn |_ _| m x 1000 CNOx,mg/NM3 = ---------- Vn Where Vn .. Dry sample volume at normal conditions, ml Vf .. Volume of flask and valve, ml Va .. Volume of absorbing solution, ml Pf .. Final absolute pressure of flask, mmHg Pi .. Initial absolute pressure of flask, mmHg Ps .. Absolute stack pressure, mmHg Ta .. Absolute ambient temperature, oK Tf .. Final absolute temperature of flask, oK Ti .. Initial absolute temperature in flask, oK CNOx .. Concentration of NOx as NO2 (dry basis), mg/NM3 m .. Micro gram of NO2 from the calibration graph _ _ | | | 735 70 | 298 Vn = (960-25) x |----- - -----| x --- | 308 308 | 760 |_ _| = 792

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700 x 1000 CNOx,mg/NM3 = ---------- Vn = 884

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----------------------------------------------------------------- S No. C O N T E N T S Page No. ----------------------------------------------------------------- 1.0 Introduction . . . . . . . . . . . . . 1 2.0 Sulfur Dioxide and sulfur trioxide (EPA - 6) . . 1 3.0 Acid mist concentration (EPA - 8) . . . . . . . 10 4.0 Nitrogen oxides estimation(EPA -7) . . . . . . . 12 5.0 Other gases . . . . . . . . . . . . . . . . 21 ANNEXURES 1 Emission standards for gaseous pollutants - CPCB . . . . 22 2 Model problem and calculation for analysis of SO2 & SO3 . . . . 25 2A Computerised data sheets for SO2 analysis . . . 30 3 Model problem and calculation for analysis of NOx . . . . 31 3A Computerised data sheets for NOx analysis . . . 33 4 Sampling and analysis of ammonia emissions. . . 34 5 Sampling and analysis of Urea emissions . . . 41 6 Sampling and analysis of Fluoride emissions . . 46 7 Sampling and analysis of H2S and CS2 . . . . . 51 8 References . . . . . . . . . . . . . . . 58 -----------------------------------------------------------------

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ANNEXURE - 7

SAMPLING AND ANALYSIS HYDROGEN SULFIDE AND CARBON DISULFIDE ___________________________________________________________ 1.0 PRINCIPLE:

The gas containing hydrogen sulfide and carbon disulfide is

initially passed through cadmium chloride solution. Hydrogen

sulfide reacts with cadmium chloride and precipitated as cadmium

sulfide which is quantitatively estimated by iodometric

titration. Subsequently the gas containing only carbon disulfide

is passed through potassium hydroxide solution where CS2 froms

potassium xanthate which is estimated quantitatively by

iodometric tritration.

2.0 SAMPLING EQUIPMENT AND THE CHEMICALS: 2.1 EQUIPMENT FOR SAMPLE COLLECTION: Sampling probe: Sampling probe made of corrosion resistant material like quartz or stainless steel Quartz wool filter: About 10mm - 15 mm dia and 150 mm long heated quartz wool filter Five Glass impingers: Mid-jet impingers of 250 ml capacity Ice bath: Leak proof ice bath to accomodate five impingers Suction pump:

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To facilitate 60 lit/hr flow rate. Gas volume meter: Suitable for 60 lit/hr flow rate. Thermometer: To measure the gas temperature at the Gas volume meter. Barometer: To measure the atmospheric pressure at the sampling site. 2.2 GLASS WARE FOR ANALYSIS: Burette: 25ml capacity with 0.05 ml minimum graduations - 2 Nos Erlenmeyer Flask: 300 ml capacity, Wide mouth with ground stopper joint.- 6 Nos 2.3 CHEMICALS: All chemicals should be of Analytical grade should be used.

Cadmium chloride solution: 25g of cadmium chloride is dissolved

with 900 ml of double distilled water in 1.0 lit volumetric

flask. Add 20 ml of 0.5N NaoH and make it upto 1.0 lit.

Iodine solution: 0.1N and 0.01N Iodine solutions

Sodium thiosulfate solution: 0.1N Sodium thiosulfate solution.

Acetic acid: 100 ml of acetic acid is diluted to 1000 ml with

double distilled water in a volumetric flask.

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Starch solution: 1.0g of starch dissolved in 100ml of double

distilled water.

Potassium Hydroxide: 5 gm of KOH dissolved in 2-3 ml of

distilled water, cooled in ice bath and make it to 100 ml with

absolute alcohol/methy alcohol.

Phenolpthaline indicator:

3.0 SAMPLING TRAIN

The sampling train is similar to that of EPA -5 for particulate

sampling except for the dust collecting thimble holder which is

replaced by a set of midget impingers for the absorption of the

gaseous components as given in Fig - A.

3.1 Sampling probe: A short sampling probe Pyrex or quartz is

used to prevent condensation prior to sample collection. Quartz

of Pyrex glass wool is placed in the entry of the probe to

prevent particulate matter/water droplets from entering the

impingers. Alternatively an additional midget bubbler stuffed

with glass wool is placed at the end of the sampling probe along

with the gas absorption equipment.

3.2 Absorption equipment: The sample collector consists of four

midget impingers placed in an ice bath. The first two midget

impingers contain 100 ml of calcium chloride solution. This

removes the H2S. To ensure efficient absorption a second

impinger with 100 CaCl2 is placed. Two impingers with 100 ml

each of alcoholic potassium hydroxide are placed in series to

absorb carbon disulfide. A fifth impinger in series is preferred

to trap the liquid droplets. It is essential to keep the the

implinger set in ice/chilled water bath to prevent the escape of

CS2 while sampling.

3.3 Flow metering: Finally the gases are passed through silica

gel drying column to protect the Dry Gas Meter which follow it.

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To achieve the optimum absorption efficiency, the sampling flow

rate has to be set at a minimum constant flow rate of 2 lpm with

the help of rota meter and the needle valve.

3.4 Vacuum pump: Since the sampling flow rates are very low the

pressure drop across the sampling train is around 10 to 15 mmHg

and hence a small capacity vacuum pump is enough for such

purpose.

4.0 SAMPLING AND ANALYTICAL PROCEDURE:

4.1 SAMPLING:

The first two impingers are filled with 100ml each of cadmium

chloride solution. The following two impingers are filled with

100 ml each of potassium hydroxide. The fifth imger is kept

empty to trap any carry over moisture droplets. Gas sample is

drawn through the probe and the quartz filter and bubbled through

the impingers. A sampling flow rate of 1.0 lpm is maintained. If

the sample time is limited then the flow rate has to be increased

accordingly. Generally the sample volumes of 30 to 50 lit are

being collected to get the repersentative data. However it

should be ensured that the absorption is completed in the first

impinger itself and the quantity of gas component in the second

impinger is negligible.

Cadmium chloride is white turbid solution and when it reacts with

H2S it becomes yellow precipitate. The strength of the color

depends on the amount of cadmium sulfide forms and care should be

taken that the sampling should be stopped before the solution the

second impinger turns pale yellow.

The reaction of CS2 with KOH can also be observed by changing its

color to pale yellow with high concentrations. care should be

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taken that the second following impinger should not change its

color.

4.2 ANALYSIS:

4.2.1 Hydrogen Sulfide, H2S:

The solution from the impingers are transfered independently in

to two iodometric flasks. Add 20 to 50ml of 0.1N iodine depending

on the quantity of CdS in the solution. Add 25 ml of 10% acetic

acid, close the stoppers and keep the flasks in dark for about 10

to 15 mts. Titrate the solution with standardised 0.1N Na2S2O3

till pale yellow and add two drops of stacrch to get dark blue

color. Continue the titration till it becomes colorless. Repeat

the titration for blank starting with cadmium chloride solution

and following the same analytical procedure parallely. Record

both the sample and blank readings.

4.2.2 Carbon Disulfide:

Transfer the contents in two 250ml Erlenmeyer flask and cool the

sample in chilled water for 10 to 15 mts. Neutralise the

solution with 10% acetic acid using phenolpthaline as indicator.

Add starch and titrate with 0.01N iodine solution till the buff

color end point appears. Repeat the procedure with blank.

5.0 CALCULATIONS: 5.1 HYDROGEN SULFIDE (H2S) Concentration of H2S in the gas sampled is calculated by the following equation (Yo - Y) x 1.702 C H2S = ----------------- Vn

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Qm x Pm x Tn Q = -------------- n Pn x Tm Where C H2S .. Concentration of H2S in the sample gas, mg/NM3 Yo .. Consumption of 0.1N sodium thiosufate by the blank Y .. Consumption of 0.1N sodium thiosufate by the sample Qn .. Sample gas volume at normal conditions,NM3 (25oC,760mmHg) Qm .. Sample gas volume, M3 P , T .. Pressure and temperature n n under normal condition (25oC,760mmHg) 1.702 .. mg of H2S per ml 5.2 CARBON DISULFIDE (CS2) Concentration of CS2 in the gas sampled is calculated by the following equation (P - Po) x 0.38 C CS2 = ----------------- Qn Qm x Pm x Tn Q = -------------- n Pn x Tm Where C CS2 .. Concentration of H2S in the sample gas, mg/NM3 Po .. Consumption of 0.1N Iodine by the blank P .. Consumption of 0.1N Iodine by the sample

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Qn .. Sample gas volume at normal conditions,NM3 (25oC,760mmHg) Qm .. Sample gas volume, M3 P , T .. Pressure and temperature n n under normal condition (25oC,760mmHg) 0.38 .. mg of CS2 per ml 6.0 RANGE OF APPLICABILITY: Minimum quantity .. 0.05 mg Minimum concentration .. 1.0 mg/Nm3 ( 50 L sample volume) Standard deviation .. 0.5 mg/NM3 at 25 mg/NM3

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ANNEXURE - 9

REFERENCES

1. Air Pollution - Vol - III, 3rd edition, A.C.Stern, Academic Press, New York 2. Emission regulations - Part-III, Comprehensive Industry Document Series, COUINDS/20/1984-85 - CPCB, New Delhi 3. EPA-Code of Federal Regulations, Title-40: Standards of Performance for new Stationary Sources - reference methods 4. Industrial source sampling, D.L. Brenchley et.al, Ann arbor Publishers, Inc., Michigan 5. Hand book of air pollution analysis, II edition - Roy.M.Harison et.al., University Press, Cambridge.

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