Abstract
The combustion process in a fluidized bed has been recognized as a promising combustion processes for Refuse Derived Fuel (RDF). To explain the behavior of chlorine compound during the combustion of RDF in the fluidized bed process, two kinds of RDF were burnt in a 0.3×0.3m bubbling-type fluidized bed combustor. One was model RDF produced from raw materials with controlled combination ratios, simulating the RDF produced from municipal solid waste (MSW), and the other was commercial RDF produced from MSW. Combustion test were carried out for a extenden period under steady state conditions. The hydrogen chloride (HCl) concentration in the flue gas was measured on various points in the process and the total weight of solid in the bed, from the cyclone, from the gas cooler and from the bag filter was measured after each test run. Material balances of silica sand, ash, and chlorine were calculated. It was found that the material balance between feed rate and outflow rate of chlorine compound agreesd within 10%. For the model RDF, 80% of fed chlorine was removed by solid components during RDF combustion in the bed and only 4.1% chlorine was discharged with the flue gas in the combustor exit. The chlorine captured by calcium remaining in the bed was 46.7% and the rest was captured by the particles entrained from the bed. For the RDF from MSW, 50% chlorine was removed by solid components in the bed and 21.9% chlorine was discharged with flue gas from the bed. 27.7% of the chlorine captured by calcium compound remained in the bed and the rest was entrained from the bed. Although potassium and sodium contained in the sand and in the RDF are assumed to completely react with chlorine, more than 80% of chlorine for the case of model RDF and more than 50% of chlorine for RDF from MSW are captured as CaCl2.
