Experiment Study On The Solid Recycle Devices In Dense Transport Bed

Wang Jiachang (Thermal Engineering) Directed by Dr. Xiao Yunhan, ProfessorThe pulverized coal pressurized dense transport bed gasification technology is a next-generation coal gasification technology, which is to adapt to the characteristics of China's development of IGCC and the developing coal-based poly-generation. This thesis is aimed to study on gas-solid flow in the solids recycle devices, one of the key unit components in dense transport bed. Through experimental research, the structures and operating conditions of the standpipe and solids feeders, which could meet the stable operation for dense transport bed, were obtained. The results could support the gasifier reactor design and operation of the overall structure.The cold experiment rig was assembled, which is round cross-section (Φ0.191×10m) with the silica sand as the bed material and the L-valve as the solids feeding device. In this experiment rig, it was found that some factors, as the system solids inventory, the standpipe construction and the aeration positions affected the solids mass flux (Gs) and the flow stability. With enlarging the standpipe's diameter and adding high position aerations, the maximum Gs can increase significantly. It was obtained that the aeration, which was located in the position of twice the diameter upon the L-valve's horizontal section, had the best ability to regulate the Gs.In order to study dense transport bed more comprehensively, a new organic glass experiment rig was founded. Three kinds of solids feeders (long inclined tube J-valve, short inclined tube J-valve and L-valve) were employed. The aerations in different positions played different role in all feeders. To achieve the maximum Gs, aeration rate of every position was required appropriate. For short inclined tube J-valve, the maximum solid mass flux in riser can reach more than 637 kg/(m2s).The results showed that the aeration in standpipe could ensure gas-solid slip velocity stability. Thereby the highly and stably particle velocity guaranteed the greater solid mass flux in the standpipe and solid feeders. Combined the operating conditions, this thesis presents the design method for solids recycle devices in dense transport bed.