emission measurement techniques and standards

8/7/2019 Emission Measurement Techniques and Standards

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Emission MeasurementTechniques

N . S . K r i s h n a n


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NDIR

Non Dispersive Infra Red Sensors

Electro optical measurement of gas by IRabsorption

Spectroscopic Device

CO2 , NO2 , CH4, SO2, etc.,


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NDIR


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NDIR Components

Infrared Source

Sample Chamber

Wavelength Filter

Infrared Detector


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NDIR Working

Sample gas into chamber

Reference gas Nitrogen

CO2 absorbs IR radiation

Amount of absorption is measuredby optical sensor


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NDIR Working


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Advantages of NDIR

High Accuracy

Extremely versatile

Less time for measurement

Low power consumption


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Disadvantages of NDIR

Needs compensation since H2O also absorbs

IR radiation of same wavelength

Low concentration of NOx and SOx cannot be

determined in case of high COx

Expensive


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FID

Flame Ionization Detector

Gas detector used in gas chromatography

Effective method for detecting Organic Compound

Presence of carbon makes FID more suitable thanany other element


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FID Principle

Hydrogen Oxy flame or Compressed air flame

Pyrolyze the organic compound

Positive Ions and Electrons are formed

Tubular Electrodes produce current from the ions

Current is fed to pico ammeter

Carrier gas flow is not a constraint

Detector is more sensitive to mass rather thanconcentration


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FID


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Advantages ofFID

Contaminated effluents can be measured

accurately

More rugged High concentration can be

measured

Sensitive measuring elements after the FIDare not damaged by the intensity of the

effluent


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Disadvantages ofFID

Insensitive to Metallic and Organic Oxides (Alcohol,

Ketone, Aldehyde , Acid, Carbonyl, Amines, Halogens,

etc.,)

FID destroys the sample so it cannot be used for any

further analysis

It should be the last stage of measuring the gas

sample


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ChemiluminescentAnalyzers

Most used method for measuring Oxides of

Nitrogen

Reaction between Ozone and NO forming

exited NO2

NO emits light with intensity proportional to

NO concentration

Photo multiplier tube for light measurement


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Advantages of ChemiluminescentAnalyzers

Internationally accepted method for

measuring oxides of nitrogen

Accurate measurement of NO

Sulfur can also be analyzed by this process


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Disadvantages of ChemiluminescentAnalyzers

Only NO and N2O can be measured

NOx has to be converted into NO for

measuring

Ozone is expensive at this rate of use


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Gas Chromatography

Gas chromatography is used for analyze compounds

that vaporize without decomposition

Separates gases with different chemical composition

and adsorption of gas with respect to temperature

It is dependent on vapour pressure of the gas

Similar to fractional distillation

Vapour phase chromatography or Gas - Liquid

partition chromatography


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Gas Chromatography


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Smoke Meter

Smoke is Visible part of the emission

Incomplete combustion

Comparison method

Obscuration method


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Ringelmann Chart


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Light Extinction Method


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Hartridge Smoke meter

Similar to Light Extinction method

Reference tube

Light source and Photo electric cell


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Continuous Filter Type Smoke meter


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SpotFiltering Type Smoke Meter

Exhaust forced to a spot of the filter paper

Pump is used to force the air

Bosch Smoke meter is an advancement of this

type

It consists of pneumatic tripping devices andelectric output instead of comparison


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Thank You

emission measurement techniques and standards

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