Abstract:
Combusting oil shale or similar fuel in a circulating fluidized bed boiler by introducing primary air to the furnace at a rate providing a fluidizing velocity of less than 2.5 m/s at the bottom part of the furnace. Advantageously, the fluidizing velocity in the upper portion of the furnace is less than 4.0 m/s, the fuel has an average particle size of about 1 mm to about 2 mm, the proportion of the primary air ranges from 35 % to 38 % of the total air introduced to the furnace, and the temperature in the furnace is maintained within the range of about 600 degrees Celcius to about 820 degrees Celcius.