Circulating fluidized bed combustion technology

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Circulating fluidized bed combustion (CFBC) technology refers to a technique in which small coal particles and air are in a boiling state within the furnace, that is, high-speed air currents come into full contact with the dense suspension of coal particles to facilitate combustion. Desulfurization in circulating fluidized bed boilers is a combustion-based desulfurization process that uses limestone as the desulfurization absorbent. Coal and limestone are fed into the boiler’s combustion chamber from the bottom, while primary air is introduced from below the air distribution plate, and secondary air is supplied from the middle of the combustion chamber. Limestone decomposes when heated into calcium oxide and carbon dioxide. The airflow causes intense agitation of the coal and lime particles in the combustion chamber, creating a fluidized bed; the SO2 present in the coal combustion gases reacts chemically with calcium oxide, thereby being removed. To improve the utilization rate of the absorbent, unreacted calcium oxide, desulfurization products, and fly ash are sent back to the combustion chamber for recycling. When the calcium-sulfur ratio reaches around 2–2.5, the desulfurization rate can exceed 90%. The characteristics of fluidized bed combustion are as follows: 1. Clean combustion, with a desulfurization rate of 80%–95%, and NOx emissions can be reduced by 50% ； 2. It has strong fuel adaptability, being particularly suitable for medium- and low-sulfur coal ； 3. High combustion efficiency, ranging from 95% to 99% ； 4. Good load adaptability. The load regulation range is 30% to 100%.