Numerical Simulation And Experimental For Flow Characteristics In Fluidized-Bed

It is a typical dense gas-solid flow system in the furnace of circulating fluidized bed boiler. Fluid dynamic characteristics of gas-solid flow in the furnace have a great impact on heat transfer, mass transfer and combustion properties. Appropriate initial bed height and inclined distributor plate not only are conducive to combustion in circulating fluidized bed, but also can reduce the abrasion of the furnace.In this paper, two flow model have been used to simulate the single jet fluidized bed .It has studied the gas-solid flowing processes and analyzed different initial bed height on fluidized bed inside the influence of gas-solid movement characteristics with simulate and experiment. The flow behavior of particles in the fluidized bed with∧-shaped and∨-shaped were investigated respectively. By changing the wind Angle and area ratio on the air distributors, observe the different of the circulating fluidized bed particle phase fluidization characteristics, for the circulating fluidized bed boiler design. Has received the following conclusions:①Based on the simulation and experimental found that, the particle concentration distribution shows a core–annular flow frame where the solid is denser in the annular region than core region and the particle axial velocity shows the internal circulation pattern that the particle movement is upward in the core zone and down in the annulus zone. With the initial bed height increases, the bubble diameter increases and gas leakage rate decreases, the pressure distribution is essentially the same, the non-uniformity of flow structure.②Via simulation of the∧-shaped and∨-shaped fluidized bed, it is found that∧-shaped distributor. Particles in the middle move downward under the low velocity and the action of gravity then move upward under the high velocity near the two sides. So the multiple fluidizations, in which fluidized bed exists at two sides, and moving bed exists in the middle, will form under this flow condition. While gas velocity in the middle is higher than that at the two sides in the∨-shaped distributor. The particles in the middle move upward under the high air velocity, then move downward under the low air velocity and gravity action at the two sides. So the multiple fluidizations, in which fluidized bed exists in the middle and moving bed exists at the two sides, will form under this flow condition.③Under the same inlet velocity, of with the increase of angle of air distribution plate, gas-solid mixing characteristics have been strengthened of the∧-shaped and∨-shaped fluidized bed. In the changing room area, there are different trends in∧-shaped and∨-shaped fluidized bed. With the reduction in area of air distribution, the gas-solid mixing characteristic of∧-shaped fluidized bed is increase, but the gas-solid mixing characteristic of∨-shaped fluidized bed is reduced.