流化床射流区域颗粒浓度分布的实验研究

Experimental Study of Particle Concentration in the Jet Region of a Fluidized Bed

为了掌握操作条件对流化床射流区域颗粒浓度分布的影响,应用光纤颗粒浓度测量系统,对直径为1 m的半圆射流流化床射流区域颗粒浓度分布进行了考察,以聚苯乙烯颗粒为物料研究了不同操作状况(环管气速,射流气速和分布板气速)对流化床射流区域时均颗粒浓度分布的影响,分析了不同操作工况下颗粒浓度分布变化的规律.结果表明:在3种气速共同作用下射流区域颗粒浓度在径向上逐渐增大,在轴向上随着气泡的逐渐增大到崩塌其颗粒时均浓度逐渐降低.由于射流气速增加导致射流深度增加,继而固体颗粒的循环速率增大,射流区颗粒的体积浓度随射流气速的增加先降低后增大.随着分布板气速的增加射流区域时均颗粒浓度增大,环管气速增加其射流区颗粒浓度逐渐降低.

The influence of operating conditions on the particle concentration in the jet region of a fluidized bed was studied using an optical fiber probe. The experiments were carried in a 1 m diameter semicircular jetting fluidized bed with polystyrene particles as the fluidized material. The time-averaged particle volume concentration was tested under different conditions, including jet gas-velocity, distributor gas-velocity and annular gas-velocity, and the change of particle concentration under different operating conditions were evaluated. The results show that the concentration of particles increased along the radial under the co-action of three gas velocities, and decreased gradually with the bubbles growth and break along the axial. With the increasing of jet gas velocity, the jet penetration depth increased and the circular velocity of solid particles increased as well. However, the concentration of particles in the jet region decreased at the start, then increased in the process. The time-averaged particles volume concentration increased in the jet region with the distributor gas-velocity increasing, and decreased with the increasing of annular gas-velocity.