O2 + O O3
However the removal of the ozone occurs when NO reacts with ozone to produce oxygen and NO2 .A constant rate is reached in the formation of ozone in reaction () and () which equals the removal rate of O3 in equation (), thus leaving the concentration rate constant.
If the concentration of hydrocarbon and oxides of nitrogen increase it would causes more hydrocarbons to break down to form CO2 and H2O. Hydrocarbons are attached by a radical OH and breaks down.
Reaction 6 is important because it converts no into no2, which in reaction () no2 is the sources of the spare oxygen atom used in the production of 03.The break down of hydrocarbon cause the concentration of o3to increase.
OH are produced when ozone absorbs light and thus break down to form an oxygen atom molecules and oxygen atom
The oxygen atom reacts with water to form OH radicals.
Ozone’s leads to the production of two radical. Each radical leads to production of two radical. Each radical leads to production of O3 via reaction ()()(()()(()()()()(()().O3 is the main ingredient that reacts to produce photochemical smog .This concentration increases. in the ozone there are two oxidising species present ,which are hydrogen peroxide ,which reacts with co no oh to produce HO2
HO2 + HO2
Second is peroxy nitrate, which reacts NO2 to produce peroxy nitrate.
The hydrocarbonis attacked by the hydroxyl radical Ohwhich cause the breakdown of hydrocarbons which can be illustrated below
BPEOS at longannet was used to minims the output of particlur waste material such as SOx and NOx Have put lonanner at forefront of the development and application of new technologny to deal with these pollutants. There are two different sorts of method of lower the emission of NOx.Most large combustion plantsuses low NOx Burners.The rate of reaction increase with temperature and if the temperature of combustion of the fuel is lower ,the rate of production of thermal NOx will be less.In the low NOx burners are air is introduced to the finely ground coal to give lower remperature flames,as a result significant reduction of thermal NOx and fuel NOx. If combustion not complete maxium haet is not realeased..high temperature stem enables most efficient conversionsof heat into electrictal energy.Gas reburn is another mehod which reduces nox emission and removes
Most large combustion plants now uses low NOx burners .In low NOx burner the introduction of air to the finely ground coal is controlled to give low temperature as a result reduction to the thermal NOx and fuel NOx. It’s important that controlled air supply does not reduce stem temperature or coal completely oxidised. High temperature stem enables conversion of heat energy into electrical energy. If the combustion is not complete the maximum heat is not released from fuel, thus stem not as high as might be.
Gas reburn is another method, which produces less NOx emission and removes any NOx formed. In Fig () in the primary combustion zone powered coal is oxidised in less air than normal, which will lower the combustion rate and less NOx produced. The injection of natural gas into the boiler just above reburning zone. No x react with alkanes to produce:
CH4 +4NO 2N2 +CO2 + 2H2O
The excess alkane are oxidised in the cooler third and heated to contribute to generating electricity.
On way of controlling SOx emission is by reacting so2 with limestone and eventually forming calcium sulphate (caSO4).The flue glue pass through the limestone process into the surry of ground limestone.
The seawater scrubbing process is less commonly used, where the sulphur dioxide are passed through seawater which has a pH of 7.5 forming sulphide ions. The water is aerated to oxidise the sulphide to more harmless sulphate and move it back into the sea. The pH changes from 7.5 to pH 6.
Photochemical smog contains much chemical substance such as ozone, which is a powerful oxidising agent a major component. Ozone is called secondary pollutant because it is formed in chemical reactions that take place when sunlight shines on a mixture of primary pollutants. Photochemical smog is formed best at high pressure (anticyclones) conditions in the lower troposphere. These conditions usually give rise to still air, in which there is little mixing with high altitude air. The pollutants are trapped closes to the ground .If an occurrence of light prevailing wind; the polluted air mass is moved from urban areas to rural regions. The highest ozone recorded was recorded over rural areas because chemical reaction producing the secondary pollutants. In 1995 the bright sunshine and still air provided the ideal condition for photochemical smog. The smog caused havoc and was very dangerous to people with asthmatics and many old and young people. As the hot weather continued, weather showed high concentration of ozone in the country.
Flue gases contain oxides of nitrogen(no) for two reasons. firstly ,fuels contain compounds of nitrogen, formed from proteins contained in organism. When the fuel is burnt ,these nitrogen compounds are oxidised to form what is called fuel NOx. secondly at high temperature of combustion ,atmospheric nitrogen and oxygen combine to form what is called thermal NO x. most of the NOx emissions are thermal NOx
All living organism contain compounds of sulphur and these are the origin of the sulphur found in coal. when coal burns ,the sulphur compounds are converted to oxides of sulphur (Sox).because some organism contain more sulphur than others, the amount of sulphur in coal varies according to the types of organisms from which the coal was originally formed.
