It is converted to a weight flow, showing the wide rage of values. Heating values are then added, showing that there isn t enough coal coming in to match the boiler need. The coal is increased to match the boiler need. The associated weight flows and heat rates are found. Air in the predicted proportion is added.
Air is corrected for distribution problems in the furnace.
Since the air is frequently supplied from a single source, each burner or cyclone will get the same amount, which has to be that amount corresponding to the largest quantity multiplied by the number of feeders. This leads to a large excess air quantity. The excess air must be heated along with the coal and combustion air and is include in the mass flow. Being gaseous, a specific heat and temperature are added, and the total heat lost is developed. The fuel required to find this heat is priced and charged based on the operating percentage.