摘要：

In a demonstration project supported by an European Community Thermie Fund a biomass gasifier for bark, wood chips, saw dust, etc. has been installed by Austrian Energy and Environment at the 137 MW{sub el} pulverized-coal fired power station in Zeltweg, Austria. The project title BioCoComb is an abbreviation for Preparation of Biofuel for Co-Combustion, where co-combustion means combustion together with coal in existing power plants. According to the thermal capacity of 10 MW the produced gas substitutes approx. 3% of the coal fired in the boiler. Only the coarse fraction of the biomass has to pass a shredder and is then fed together with the fine fraction without any further pretreatment into the gasifier. In the gasification process the biomass will combust in a substoichiometric atmosphere, create the necessary temperature of 820 C and partly gasify due to the lack of oxygen in the combustion chamber (autothermal operation). The gasifier uses circulating fluidized bed technology, which guarantees even relatively low temperatures in all parts of the gasifier to prevent slagging. The intense motion of the bed material also favors attrition of the biomass particles. Via a hot gas duct the produced low calorific value (LCV) gas is directly led intomore the furnace of the existing pulverized coal fired boiler for combustion. The gas also contains fine wood char particles, that can pass the retention cyclone and burn out in the furnace of the coal boiler. The main advantages of the BioCoComb concept are: low gas quality sufficient for co-firing; no gas cleaning or cooling; no predrying of the biomass; relatively low temperatures in the gasifier to prevent slagging; favorable effects on power plant emissions (CO{sub 2}, NO{sub x}); no severe modifications of the existing coal fired boiler; and high flexibility in arranging and integrating the main components into existing plants. The plant started its trial run in November 1997 and has been in successful commercial operation since January 1998.less

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