The fluidized-bed reactor is a system where the heat transfer rate is rapid. This design gives low liquid yields and high gas yields. In the fluidized bed, the feed is injected into a hot bed of agitated solids. To keep the bed in the fluid state, the system passes gas upward through the bed. If air is introduced into the bed, the oxygen contacts and reacts with the pyrolysis gas more readily than the char does, reducing the gas yield. To assure that the produced pyrolysis gas does not react with oxygen, operators can remove the char produced and burn it in a separate unit and return the hot gas used to pyrolyze the feed into the fluidized bed. The capacity is limited by the sensible heat available from this gas. In a fluidized bed, circulating the solids in the bed adds heat. The heat source necessary to pyrolyze the feed can be heated solids which can be easily added and removed in the fluidized bed.
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