Experiment On The Adjusting Characteristics Of A Pneumatic Distribution Valve

With the development of circulating fludized bed technology, there appears many new technology, for instance, circulating fluidized bed multi-generation systems and related systems with extenal beds. The critical technology of the systems is distribution of the hot ash. The distribution of the hot ash, a part return to pyrolysis chambers and other part retrun to parallel fluidized beds is diffcult for multi-genneration systems and dual-bed systems.Based on a review of the existing research works, a new type of pneumatic control distribution device, so called as Pneumatic Distribution Valve (PDV), was designed. The boundary condition and the adjusting characteristics of the PDV were studied, its work principle was analysed with experiment results.The cold test rig of PDV was a unit rig. The returning critical pressure and the rate of discharge of the soild material were investigated under different pressures, fluidization air and leg heights of sand.The experiments results demonstrate that the returning critical pressure of the fixed structure PDV is not invariable, but changes along with the control parameter. Adjusting the control parameter can enlarge the PDV working region at the certain range which is very limited. This PDV has a good capability of adjusting the rate of discharge of the soild material when the pressure is smaller than the returning critical pressure.Based on the experiments, the controlling mechanism of PDV is given, the pressure distribution in PDV and the relationship between upward gas and pressure distribution is analysed. The quantity of upward gas is calculated by experiments result, and usablity of the Ergun formula in PDV is analysed.