Comparative study on flow characteristic of supercritical water fluidized bed and traditional fluidized bed

Supercritical water fluidized bed is a novel efficient gasification reactor, its flow characteristics is diverse from that of traditional gas-solid fluidized bed. The contrast of flow characteristics is made between supercritical water fluidized bed and traditional gas-solid fluidized bed with the model which is developed based on DEM-CFD coupled method. According to the simulation, we can get following result: traditional gas-solid fluidized bed translate to the bubbling fluidized state when the inlet superficial gas velocity is just above minimum fluidization velocity, while supercritical water fluidized bed experiences a period of uniform expansion after the superficial gas velocity exceeds the minimum fluidization velocity, then it reaches the bubbling fluidized state; bed pressure drop fluctuations of supercritical water fluidized bed is less than that of traditional gas-solid fluidized bed; supercritical water fluidized bed has a higher bed expansion height under the conditions of the same fluidization number (u/u_mf); In the bubbling fluidized state, the bubble diameter increase with the rise of the bed height in both of the fluidized bed; the average equivalent bubble diameter of supercritical water fluidized bed is less than that of the traditional fluidized bed under the conditions of the same fluidization number.