加压循环流化床气固流动特性实验研究Ⅱ:气固滑移特性

Experimental research of gas-solid flow behaviors in pressurized circulating fluidized bed—Ⅱ:gas-solid slip behaviors

针对加压煤燃烧、气化和化学链燃烧的发展需求,建立了一种上升管内径为0.068m、高5.2 m的加压循环流化床冷态实验装置,研究了不同操作压力(0.1～0.5 MPa)下,平均粒径为137μm、密度为2 490 kg/m3的Geldart B类颗粒的气固滑移特性.实验结果表明,在固体通量和状态表观气速一定的情况下,随操作压力的增加,上升管内颗粒的表观滑移速度和表观滑移因子逐渐减小,但并未对上升管内的气固滑移特性造成本质影响.与常压情况类似,加压下表观滑移速度、状态表观气速和表观颗粒体积分数之间存在显著的相关性.无量纲滑移速度随表观颗粒体积分数的增加呈幂函数型增加,表观滑移因子随无量纲滑移速度的增加呈指数型增加.

According to the development requirement of pressurized coal combustion, gasification and chemical looping combustion, a cold-model experimental facility of a pressurized circulating fluidized bed with the riser diameter of 0.068 m and the height of 5.2 m is built. The slip behaviors of Geldart group B particles with the mean diameter of 137 μm and the density of 2 490 kg/m3 are investigated under different operating pressure （0. 1 to 0.5 MPa）. The experimental results show that both the average slip velocity and the slip factor decrease with the increase of the operating pres- sure under the same pressurized state apparent gas velocity and solid mass flux. The elevating operat- ing pressure does not essentially influence the gas-solid slip behaviors in the riser. At the elevated pressure, the significant correlation exists among the average slip velocity, the pressurized state superficial gas velocity and the apparent solid holdup, which is similar to the relativity at the atmos- pheric condition. The dimensionless slip velocity increases with the increase of the apparent solid holdup following the power function. In addition, the average slip factor increases exponentially with the increase of the dimensionless slip velocity.