flue gas analyser

7/30/2019 Flue Gas Analyser

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FLUE GAS ANALYZERS AND

AMBIENT AIR ANALYZERS



USE OF ANALYZERS IN POWER

PLANTAnalysers are used in power plant for

optimisation of fuel firing and monitoring

the environment.



TYPES OF ANALYZERS

IN-SITU ANALYSERS (CROSS DUCT

ANALYZERS)

EXTRACTIVE ANALYZERS



ANALYZERS USED AT NTPC-RIHAND

•OXYGEN ANALYZERS

•OPACITY ANALYZERS (SMOKE DENSITY)

•CO ANALYZERS

• NOX ANALYZERS

•SOX ANALYZERS

•CO2 ANALYZERS

•AMBIENY AIR ANALYZERS (SOX,NOX,CO2 AND SPM)



OXYGEN ANALYZERS

•Oxygen analysers are used to monitor the optimum air flow toboiler.

•Excess air is provided to boiler to reduce the unburnt particles

and to provide air in case coal quantity demand increased rapidly.

•Oxygen analysers are also used to detect the leakages in flue gas

ducts.



OXYGEN ANALYZERS

Installed location :

1. Flue gas economiser outlet

2. Flue gas outlet of APH (air pre heaters)

3. ID fans inlet

4. First pass of boiler at 65 meters



OXYGEN ANALYZERS

Principle: The Zirconia sensor works on the principle of NernstThe sensor works on ionic conductivity of the Oxygen ions (movement

of oxygen ions through the Zirconia) which produces a potential across

the Zirconia cell, based on the difference of partial pressure of the

oxygen across the Zirconia cell .

The formation of ions, and its movement across the Zirconia requires

that the temperature of the Zirconia is raised to above 600ºC. This is

achieved by either keeping the sensor at temperature above 600ºC, or by

heating the Zirconia cell.



OXYGEN ANALYZERS

The potential generated follows the Nernst Equation given below,

• which is used for calculating the oxygen percent from measured

values.

• E = 0.0215 * T * Ln(Pr/Px)

• where,

• E = Zirconia Cell voltage in millivolts

• T = Thermocouple temperature in Kelvin

• Pr = reference partial pressure

• Px is the unknown process oxygen in percent• 0.0215 is the cell constant

• 20.9 is the partial pressure of the oxygen of dry atmospheric air



OXYGEN ANALYZERS

• Construction and installation



OXYGEN ANALYZERS



OXYGEN ANALYZERS

Maintenance

• ROUTINE CALIBRATION

• TIMELY REPLACEMENT OF ZIRCONIA SENSOR

• NO LEAKAGES AT PROBE

• REFERENCE AIR FLOW AND PRESSURE TO BE MAINTAINED

• FILTER TO BE ROUTINELY CLEANED OR REPLACED



OPACITY ANALYZERS

• Opacity Analyzers are used to monitor the quantity of flue gases

discharge from boiler.

• These Analyzers provide an opportunity to measure the effectivenessof ESP(ELECTRO STATIC PRECIPITATOR)



OPACITY ANALYZERS

Installed location :

1. ESP outlet

2. chimney



OPACITY ANALYZERS

PRINCIPLE: When a beam of light crosses a medium containing

smoke or dust particles, some of the light is transmitted and some is

lost due to scattering. The fraction which is transmitted is called the

transmittance and the fraction which is lost is the opacity.

Transmittance = I / Io *100 %

I= intensity of light recieved

Io= intensity of light emitted

Hence opacity = 1-transmittance =(1- I/Io) *100%



OPACITY ANALYZERS

LAMBERT-BEER LAW : The law describes the correlation between the attenuated

light intensity(I) and dust concentration (c) on the measuring path (x)

-c*x*k I =Io *e

I= intensity of the light received

Io=intensity of the light emitted

K =extinction coefficientC =dust concentration

X = path length



OPACITY ANALYZERS

• Construction and installation



OPACITY ANALYZERS



OPACITY ANALYZERS

Maintenance

• ROUTINE CALIBRATION

• CLEANING OF BLOWER’S AIR FILTER

• CLENING OF FAIL SAFE SHUTTER



SAMPLE HANDLING SYSTEM FOR EXTRACTIVE

TYPE ANALYZERS



NON DESPERSIVE ANALYZERS

A simple single-beam analyzer




non-dispersive analysis begins with a light beam passingthrough a sample substance, often enclosed in a windowedsample chamber (typically called a cell ). Certain “species”of gas introduced into this cell absorb part of the incidentlight, leaving the light exiting the cell partially depleted of specific wavelengths. As the concentration of any light-absorbing gas increases in the cell, a detector placed at theother end of the cell receives less and less light of theabsorbed wavelengths. The simplest style of non-

dispersive analyzer uses a single light source, shiningcontinuously through a single gas cell, and eventuallyfalling on a small thermopile (converting the receivedinfrared light into heat, and then into a voltage signal):




placing a filter cell in the path of the light to absorb all the

wavelengths associated with the gas of interest, leaving all other

wavelengths unattenuated. One application of this technique is

called Gas Filter Correlation, or GFC Spectroscopy. (NEGATIVE

FILTERING)



CO,CO2 ANALYZERS



FLOUORESCENCE ANALYZERS

• When a high-energy photon strikes an atom, it may eject one of the lower-levelelectrons from its shell, leaving a vacancy to be filled by one of the electronsalready residing in a higher-level shell. When this happens, the electron fillingthat lower-level vacancy emits a photon of less energy than the one responsiblefor ejecting the original electron. Thus, a high-energy photon strikes the atom,and in turn the atom releases a low-energy photon. This phenomenon is known

as fluorescence.• The relationship between a photon’s energy and its frequency (and

correspondingly, its wavelength) is a well-defined proportionality of Planck’sconstant h:

•

•

• Where,

• E = Energy carried by a single “photon” of light (joules)• h = Planck’s constant (6.626 × 10-34 joule-seconds)

• f = Frequency of light wave (Hz, or 1/seconds)

• c = Velocity of light in a vacuum (≈ 3 × 108 meters per second)

• λ = Wavelength of light (meters)



SO2 ANALYZERES

• Sulphur dioxide (SO2) is an atmospheric pollutant formed by the combustion of fuels containing sulfur. This gas also happens to exhibit fluorescence under

ultraviolet light.



CHEMILUMINESCENCE

• Some exothermic reactions release energy primarily in the form of light rather than heat.The general term for this effect is chemiluminescence.

• Certain industrial compounds engage in chemiluminescent reactions, and this

phenomenon may be used to measure the concentration of those compounds. One such

compound is nitric oxide (NO), an atmospheric pollutant formed by high-temperature

combustion with air as the oxidizer.



NOX ANALYZERS

• A spontaneous chemical reaction between nitric oxide and ozone is known to produce chemiluminescence:

NO + O3 → NO2 + O2 + light



EXTRACTIVE TYPE ANALYSERS

MAINTENANCE

• FLOW LINE TO BE ROUTINELY CHECKED.

• HEAT TRACE LINE TO BE CHECKED

• PURGING SYSTEM TO BE CHECKED

• FILTERS TO BE CLEANED ROUTINELY

• CALIBRATION TO BE DONE ROUTINELY

• AIR LEAKAGES TO BE CHECKED



PARTICULATE MONITOR PM10 ,PM2.5

WC = MEASURING CHAMBER

CC = COMPENSATION CHAMBER

RS = RADIOACTIVE SOURCE

C = CHAMBER FOR PARTICULATE DEPOSITION AND MEASUREMENT

RS-C-WC = MEASUREMENT SECTION

RS-CC = COMPENSATION MEASUREMENT SECTION

F1, F2 = FILTER REELSFigure



PARTICULATE MONITOR

• In operation, suspended particles in ambient air are pulled through the PM10 inlet head

at a flow rate of 16.7 L/min. The inlet head consists of a series of impaction plates to

segregate particulate matter by size.Because of the design of the inlet, accurate sampling

is accomplished independent of wind speed anddirection.

• Air is drawn into the inlet and deflected downwards into the acceleration jet of theimpact unit. Because of their greater momentum, particles larger than the 10 micron

cutpoint impact out and are retained in the middle plenum impaction chamber, as

illustrated in Figure The particle fraction smaller than 10 microns is carried upward by

the air flow and down the vent tubes to the beta gauge sampler.



PARTICULATE MONITOR

C

14

•After traversing the inlet configuration, the PM10 particles are deposited on a glass fiber filter tape. Alow level of beta radiation is emitted from thesource and passes through the filter tape anddeposited particles. The increase of particlescollected on the tape causes a lower beta-raymeasurement in the measuring chamber, asillustrated in Figure This filter-spot position resultsin a continuous observation of the increasing

particulate mass and corresponding concentration.A compensation chamber receives an equal portionof the beta-ray and is used as a reference bycomparing the sample measurement in themeasuring chamber with transmitted radiationthrough a compensation chamber foil that exhibitsthe same absorptivity as clean filter tape.

As particles collect on the filter, the differential

reading changes, and the signal is converted by anonboard computer to PM10 concentrations.



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flue gas analyser

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