喷管型气体分布器和颗粒物性对提升管内气固两相流动行为的联合影响

Combination Effect of Nozzle Gas Distributor and Particle Properties on Gas-Solid Flow Behaviors in CFB Risers

在两套均采用喷管型气体分布器的循环流化床实验装置上分别采用河沙和FCC颗粒系统测试了提升管内的轴向压力梯度分布和局部颗粒浓度,研究了气体分布器结构和颗粒直径及密度对上行气固两相流动行为的共同影响。结果表明,当表观气速小于8.0m?s?1时,粗重的河沙颗粒在喷管型气体分布器效应逐渐消失的过程中会出现不同程度的减速,而细轻的FCC颗粒在本实验的测试范围内则不存在上述现象。当采用喷管型气体分布器时,粗重的河沙颗粒在加速过程中,不仅其颗粒浓度显著高于FCC,而且其沿径向分布的不均匀程度也明显大于FCC;但在充分发展段,河沙的颗粒浓度不仅比FCC低,而且在径向的分布也更为均匀。

The influence of nozzle gas distributor design on the axial and radial flow structure for FCC and sand particles was investigated in two 100 mm i.d., 15.1 m and 10.5 m long risers with nozzle gas distributor separately by measuring axial pressure gradient profiles, axial and radial profiles of solids holdup. Results show that the nozzle gas distributor design has different effects on the axial and radial flow structure for the FCC and sand particles. At lower superficial gas velocity of less than 8.0 m.s^-1, the upward gas-solid flow of the sand particle decelerates to various degrees with the disappearance of nozzle gas distributor effect. The upward gas-solid flow of the FCC particles, however, does not have noticeable deceleration although the nozzle gas distributor design is also used. It is also found that, when the nozzle gas distributor is employed, the radial distributions of local solids holdup of the FCC particles in the acceleration section are more uniform than those of sand particles under the same operating conditions; while in the fully developed zone, the radial distributions of local solids holdup of the sand particles are more uniform than those of the FCC particles under the same operating conditions.