Combustion

Combustion is the formation of heat and other combustion products by the reaction of fuels with oxygen. We perform combustion by mixing the fuel with the oxygen in the air. Whether this amount of air is less or more than necessary determines the characteristics of combustion. Therefore, the amount of heat generated and the type and amount of other combustion products are determined by the combustion air. Therefore, the combustion in the fuel-air mixture, depending on the weather, we call

            a) Combustion with little air

            b) Combustion with excess air

            c) Complete combustion.

a) Combustion with little air

The most distinctive feature of combustion with little air is that the laser gas is very dark and sooty. In addition, the flame color is darker than it should be. In addition, when the measurement is made with the flue gas analyzer, CO (carbon monoxide) will be seen too much. In this case, smut and soot will accumulate on the heat transfer surfaces and heat transfer will be difficult. Our fuel consumption increases both for this reason and because we cannot convert all of the chemical energy of the fuel we burn into heat. In addition, we cause environmental pollution because we exhaust CO, flue gas, soot and smut from the chimney, which is a toxic gas.

As it is known, this is a great harm to both the business economy, the country's economy and the environment we live in.

b) Combustion with excess air

In case of combustion with excess air, the flame color is very light and bright. Flue gas is almost invisible. In this case, the furnace temperature drops. The flue gas temperature increases. So we have to burn more fuel to get the same amount of steam. As we burn more fuel, we exhaust more flue gas. Therefore, we pollute the environment more than necessary. Again, a negative situation will arise in terms of both the business economy, the country's economy and environmental health.

This means that burning with too little air and burning with too much air are equally harmful.

c) Complete combustion

In complete combustion, the flame color is usually light yellow – orange in solid and liquid fuels. In gaseous fuels, it is blue. If there is no combustible material in the combustion products and the remaining parts, the combustion is complete combustion. The presence of CO (carbon monoxide) in the flue gas will both harm the environment and increase the amount of fuel. In addition, with the O2 measurement, it should be investigated whether the combustion is in the direction of excess air. Apart from these, flue gas temperature also plays a direct role on boiler efficiency. The flue gas temperature depends on the fuel type and fuel components. In fuels containing sulfur and sulfur compounds, the flue gas temperature should not be lowered below 160°C. Otherwise, sulfur combines with the oxygen and hydrogen in the air, allowing the formation of sulfuric acid. In an ideal combustion, the flue gas should consist of carbon dioxide and nitrogen gas. But we usually do the combustion with some excess air. In addition, since there is no sulfur in natural gas, the flue gas temperature can be reduced to 56°C. An increase in the amount of carbon in the fuel causes the color of the flame to turn red, and an increase in the amount of hydrogen causes an increase in the amount of water (water vapor) formed as a result of combustion. As a result of a good combustion, there should be 12-13% CO2 in the flue gas, and the amount of CO should be as low as possible.