Tuesday, February 12, 2013

HOW TO IMPROVE AIR QUALITY BY CONTROLLING AIR POLLUTION

Premature combustion of petrol in car engines result in knocking which causes loss in the power of the car.To prevent knocking,lead compounds such as tetra-ethyl lead is added to the fuel.however,during combustion,the lead compound react with other addictives in petrol to form a volatile lead halide which comes out of the car exhaust as smoke..lead is toxic,it causes anaemia,damages the nervous system and the kidney..thus it is therefore needed to use unleaded petrol to reduce the amount of toxic lead compound in the air..So the first point here is THE USE OF UNLEADED PETROL..

INSTALLATION OF CATALYTIC CONVERTER IN CAR EXHAUST SYSTEM
NO,CO and unburnt hydrocarbon present in car exhaust sysem makes it a major source of air pollutants.the installation of catalytic converter in the car exhaust system helps to reduce the emission of these pollutants..after installation of these converter..oxidation and reduction takes place.CO is oxidized to CO2..NO is reduced to N,unburnt hydrocarbon is oxidized to CO2 and H2O...The converter catalyst includes precious metal as RHODIUM,PLANTINUM[oxidation] and PALLADIUM..these catalyst are poisoned by lead..that is why it is essential to use UNLEADED PETROL..

DESULPHURIZATION OF FLUE GAS
A major air pollutants is released during the combustion of coal which contains sulphur,by using coal of low sulphur content,the quality
of SO2 emission will be reduced greatly..the generating unit coal-fired plants in many countries is equipped with a flue gas...A system called  THE WET LIMESTONE GYPSUM PROCESS SCRUBY PROCESS  which is capable of removing 90 percent of the SO2 emitted from the boiler plant when burning coal with a wide range of sulphur.Flue gas from the boiler plant is directed to the absorber which contain a recycle slurry of limestone for the removal of SO2.The CAS04 formed is oxidized to CASO4[VI] by the air blown to the bottom part of the absorber.The chemical reaction of the absorbing and oxidation process can be represented as
SO2 +H20-----H2SO3 [ABSORPTION]
CACO3 +H2SO3----CASO3+CO2+H20 [NEUTRALIZATION]
CASO3 + 1/2 O2-----CASO4 [OXIDATION]

CASO3 +1/2 H20------CASO3.1/2H20 [CRYSTALLIZATION]

CASO4 +2H20-------CASO4.2H2O [CRYSTALLIZATION]

The treated flue gas leaves the absorber and is then directed to the chimney for the disposal to the atmosphere..The gypsum bye product has a purity of over 90percent, it is exported for industrial application for the production of cement..

INSTALLATION OF ELECTROSTATIC PRECIPITATOR IN POWER PLANT
Coal always contain a proportion of starch which cannot be burnt..the power plants should be equipped with electrostatic precipitator..the flue gas from the boiler is then passed through a chamber and become charged.the charged particle later get attracted to a collecting electrode..the charges on the particles are neutralized on the collection electrode where they are deposited or precipitated and removed.the clean flue gas is then discharged through the chimney..

INSTALLATION OF LOW NITROGEN OXIDE BURNER IN POWER PLANT
Nitrogen monoxide and nitrogen dioxide, they are formed during combustion of fuel in two ways.
nitrogen in the air reacts in a series of complex reaction to form nitrogen monoxide
N2 + O2-------2NO

when released into the atmosphere NO reacts with O2 to form NO2
2NO + O2-------2NO2

They are known as thermal NO2 because of the way they are formed..fossil fuels contain nitrogen compounds,when the fuel are burnt, the nitrogen compounds are oxidized,the NO formed in this way are called ''FUEL NO''.power plants should be equipped with low  NO burner system..this system utilizes a combustion control method in which the operating condition for combustion are modified to reduce NO formation..The combustion control method limits the formation of NO in the burner by

REDUCING THE FLAME TEMPERATURE IN THE COMBUSTION ZONE
REDUCING THE AVAILABILITY OF OXYGEN GAS IN THE NO FORMATION ZONE..

So if the above are strictly followed,it will greatly cause reduction in environmental pollution most especially air pollution and also cause a significant reduction in various disease such as cancer,anaemia,impaired lung cleavage,heart disease and so many others and the world will be a better place to live in...

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