Patent ID: 8506917
Filing Date: 2013-08-13
Classification: B01D,C01B,C10J,C10K,F23J

Abstract:
1. A gas treatment method for a circulating fluidized-bed gasification system, the circulating fluidized-bed gasification system comprising: a combustion furnace in a cyclic material flow communication with a cyclone collector and a gasification furnace; a catalytic denitrator in material communication with the cyclone collector; an ammonia remover in material communication with the gasification furnace; wherein the ammonia remover is in material communication via control valves with the catalytic denitrator and the combustion furnace; and the method is conducted in the circulating fluidized-bed gasification system in a sequence of operations, comprising: introducing a raw material and gasifying agent to the gasification furnace; adding a bed material to the gasification furnace to form a fluidized bed; gasifying a portion of the raw material over the fluidized bed passing gasified raw material to the ammonia remover to separate ammonia, passing char, raw material not gasified and bed material from the gasification furnace to the combustion furnace, adding an oxygen comprising gas to the combustion furnace to oxidize the raw material to obtain a gaseous oxidation mixture comprising nitrogen oxides, passing the oxidation mixture to the cyclone collector to separate bed material from the gaseous oxidation mixture and returning the separated bed material to the gasification furnace, passing the oxidation mixture as an exhaust to the catalytic denitrator, feeding gaseous ammonia separated in the ammonia remover to the catalytic denitrator, catalytically reducing the nitrogen oxides to nitrogen with the ammonia, wherein a flow rate of the ammonia to the catalytic denitrator is regulated such that a molar ratio of ammonia from the ammonia remover to nitrogen oxides in the exhaust gas from combustion furnace is kept within a setting range, a remainder of the ammonia off-gas being fed to the combustion furnace.