Combustion control retrofits

Combustion Process

The most common fuels consist of carbon and hydrogen. Combustion is the rapid oxidation,
i.e., rapid combination with oxygen, of a fuel release heat. Stoichiometric, or perfect, combustion combines the exact proportions of fuel and oxygen to obtain complete conversion of the carbon and hydrogen to yield water vapor, carbon dioxide, and heat. The ideal proportions of fuel and air vary directly with the BTU content of the fuel. Too much air results in energy losses up the stack. Insufficient air results in loss of heat generation due to incomplete fuel combustion.

A certain amount of excess air is required to ensure that complete combustion occurs within the combustion chamber and to compensate for delays in fuel-air ratio control action during load changes.

The purpose of the combustion control system is to maintain constant steam pressure at the super heater outlet header for all loads by varying the rate of combustion in boiler furnaces. The control also maintains the proper ratio of fuel and air at all rates of combustion.

To change the steaming rate, the automatic combustion control must adjust the following:
1. Fuel oil to the furnace
2. Combustion air to the furnace

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