Note on Process of Air Demand Combustion

Introduction:

We will discuss about the process of combustion. Combustion should be an exothermic chemical response, which is go with by growth of heat and light at a quick rate. Combustion is an exothermic reaction, in which a fuel burns in the presense of oxygen with evolution of heat and light. The chief elements present in most of the fuels are C and H. In addition, a trace amount of S, N are also present.

The Process of Combustion

These are the process of combustion

• The formula should be based on the following process assumptions.
• 1- Most of the fuels have C, H, S and O.
• 2- Calorific value is the sum of the calorific value of each element.

Therefore, the Dulong's formula can be written as follows:

GCV = 1/100 [8080 C + 34500 (H-O/8) + 2240 S] k cal/kg

C, H, O & S - % of C, H, O & S in the fuel.

LCV = (HCV-0.09H×587) k cal/kg

Process of Air Demand Combustion:-

To find the amount of oxygen and therefore the amount of air requisite process for the combustion of a component of a fuel, it is essential to be relevant the subsequent basic principles:

• Substances always combine in definite proportions and these proportions are determined by the combustion molecular masses of the substances process involved and the products formed. For example, when carbon combines with oxygen to form carbon dioxide, the equation will be,

C + O₂ ---> CO₂ + 97k cal

indicates that mass extent of hydrogen, oxygen and carbon dioxide produced are 12:32:44 correspondingly.

• Air contains 21% of oxygen by volume, and mass percent of oxygen is 23. This means that 1 kg of oxygen process is supplied by,

1×100/23 = 4.35kg of air.

• Molecular mass of air is in use as 28.94 g/mol.

• Minimum oxygen required = Theoretical oxygen required - Oxygen present in the fuel.

• Minimum oxygen required should be calculated on the basis of complete combustion. If the combustion products contain CO and O₂ is found by subtracting the amount of O₂ required to burn CO to CO₂.