Experimental investigation on flow properties of biomass and pulverized coal binary powder mixtures

Co-gasification of coal with biomass is a novel way to utilize biomass energy and is a new research focus in clean coal technology. A thorough knowledge of the flow properties of biomass and coal binary mixtures is critical for proper processing of feedstocks to solve annoying flow problems which frequently occur in the equipment. In this paper, the flow properties (angle of repose, packing properties, and gravity discharge rate) of different biomass materials and pulverized coal binary powder mixtures were analyzed experimentally with a powder comprehensive characteristic tester and a gravity discharge experimental facility. The effects of the mixture ratio on the flow properties of different binary powder mixtures were investigated. Results indicate that the effects of the mixture ratio on the angle of repose for mixtures with different biomass species are different. For different biomass species, the bulk densities and tapped densities of their mixtures with coal decrease with increased mixture ratio. In the range of 0 similar to 50% biomass mass content, as the mixture ratio increases, the discharge rates of different mixtures first increase, then decrease. When the biomass mass content is larger than 50%, arching phenomenon can be observed near the hopper outlet. A modified prediction model was proposed for the discharge rates of mixtures, with an error range from -45% to +25%.