Alternative fuels — How to increase the use of coarse alternative fuels in the cement industry

Abstract

Alternative Fuels are successfully used in the Cement Industry in order to reduce production costs, to preserve fossil fuel resources and to minimize anthropogenic CO2 emissions. For co-combustion with standard equipment in cement plants the waste derived fuels have to be prepared in mechanical fuel preparation plants. The fuel must be sized to less than 25/80 mm so that it is entrained in the gas stream or flame and totally burns out within the short retention time in the calciner or in the kiln. To increase the fuel input especially of coarse alternative fuels e.g. tires chips with dimension up to 150 mm, an adapted fuel handling and dosing system is necessary. Alternatively to the direct dosing into the calciner, coarser fuels with dimension of up to 300 mm can be treated in a specialized combustion system that is connected to a standard calciner system. The paper gives insight into the introduction of tire chips to a calciner in Morocco and the arrangement of the first installation of the “Step Combustor” system in Germany.