Catalytic Combustion in a Fluidized Bed: Achievements and Problems
A catalytic method of combustion of a solid fuel in a fluidized bed is compared with a noncatalytic method. It is shown that the use of catalysts reduces the fuel consumption and sizes of heat generators approximately by an order of magnitude, while the specific load on the reactor volume increases by more than a factor of 20. Emission of toxic substances with fuel combustion products drastically decreases. Comparative stability of oxide non-platinum catalysts is estimated in the course of catalytic burning of the fuel with addition of an inert material. In burning fuels with a large content of sulphur, the maximum deactivation is found to occur within the first several tens of hours; this process is accompanied by sulphur accumulation in catalysts. Later on, the catalyst activity remains almost unchanged. It is found that a critical factor of catalyst stability is attrition resistance. The prospects of fuel burning in a layer of cermet honeycomb catalysts are demonstrated. Pilot tests of the brown coal combustion over porous honeycomb cermet catalyst bed have been carried out. The higher coal combustion as well as a low emission of gas contaminants compared to non-catalytic combustion had been demonstrated. Some processes of the catalysts’s ageing have been studied and discussed. The catalyst reveals a good attrition resistance making it promising for the oxidation of other solid particulate fuels like lignite and peat as well as wastes.
Support by RFBR Projects No 14-08-00251a is gratefully acknowledged