1. The amount of air required for combustion
The oxygen required for combustion is generally obtained directly from the air. If the small amount of carbon dioxide and other rare gases contained in the air are not considered, the volume composition of dry air can be calculated as 21% oxygen and 79% nitrogen.
During the combustion of gas, an appropriate amount of air should be supplied, too much or too little will have an adverse effect on combustion.
2. Theoretical air requirement
Theoretical air requirement refers to the amount of air required for complete combustion of 1m (or kg) of gas according to the combustion reaction measurement equation, which is the minimum amount of air required for complete combustion of gas, and the unit is m/m or m/kg when the gas component When known, according to the reaction equation of each component, the theoretical air volume required for gas combustion can be calculated.
3. Actual air requirement
The theoretical air requirement is the minimum amount of air required for complete combustion of the gas. Since the mixture of gas and air is difficult to achieve complete uniformity, if only the theoretical amount of air is supplied in the actual combustion device, it is difficult to ensure sufficient mixing and contact of gas and air, so complete combustion cannot be achieved. Therefore, the actual amount of air supplied should be greater than the theoretical air demand, that is, a part of excess air should be supplied.
The existence of excess air increases the chances of the gas molecules contacting the air molecules, and also increases their chances of interaction, thus promoting their complete combustion.
In the combustion process, correct selection and control. The size of the value is very important, if a is too small or too large, it will lead to bad results. If a is too small, it will lead to incomplete combustion, resulting in waste of energy and pollution to the environment; if a is too large, the volume of the flue gas will increase, and the temperature of the furnace and flue gas will decrease, resulting in a decrease in the heat transfer efficiency of the heat exchange equipment and heat loss from the exhaust gas. The increase also causes a waste of energy. Therefore, advanced combustion equipment should try to make the value of a close to 1 under the premise of ensuring complete combustion.