Experimental Study On Pneumatic Distribution Valve Of High Solids Flux

Dual bed technology of coal pyrolysis and gasification is the key technology for clean utilization of low rank coal. For dual bed gasification technology, one of the key issues is pneumatic distribution valve of high solids flux.Experiments were carried out in a unit experiment rig of pneumatic distribution valve and a dual-bed rig with silica. The effect of structural and operating parameters of distribution valve on the circulating and regulating characteristics were studied. The main results were as follows:1. Unit experiments of pneumatic distribution valve:1) For unit experiments, two kinds of pneumatic distribution valve were researched. Both solids flow rate increased with the increasing of their own fluidization number of the fluidized gas and the loosed gas on both single-side and dual-side performance when it was less than the maximum solid circulating rate. For pneumatic distribution valve of two U valves, distribution ratio of one side changed from0to80%; For pneumatic distribution valve of U and L valves, distribution ratio of side L valve changed from10%to65%;2)For pneumatic distribution valve of two U vales, the height of splitter plate had effect on single-side performance. With the increasing of the height of splitter plate, solids circulating rate increased. But the height had little impact on dual-side performance. Compared with pneumatic distribution valve of U-L valve, distribution valve of two U vales was more suitable for stable solid circulation and distribution under high solid flux.2. Dual-bed experiments of pneumatic distribution valve:1) Good regulating characteristics were achieved under the max total solids circulating rate GS,t(400kg/(m2·s))(solids circulating rate in riser670kg/(m2·s)) in dual-bed system. The solids circulating rate and distribution ratio of side of stand pipe and side of fluidized bed increased with the increasing of their own fluidization number of fluidized gas and the fluidization number of loosed gas on dual-side performance. As changing the fluidization number of loosed gas, distribution ratio of side of fluidized bed changed between31%and45%(the fluidization number of side of stand pipe) and between31%and45%(the fluidization number of side of fluidized bed); As changing the fluidization number of loosed gas, distribution ratio of side of fluidized bed changed between15%and54%(the fluidization number of side of stand pipe) and between10%and53%(the fluidization number of side of fluidized bed); The performance of fluidization number of fluidized gas was better than the fluidization number of loosed gas. With the increasing of total solids circulating rate GS,t, the solids circulating rate of both sides increased and distribution ratio of both sides had little difference.2) The height of splitter plate had effect on the solids circulating rate and distribution ratio. With regulating fluidization number of fluidized gas, the corresponding regulating side of pneumatic distribution valve which had no splitter plate achieved higher distribution ratio. With the increasing of the pressure difference of two sides exit, solids circulating rate of higher pressure side decreased gradually and to zero finally. The critical pressure difference was2400Pa.3) The ratio of solids circulating rate and the ratio of fluidized number of two sides had good empirical correlation.