基于PIV的注液流化床内颗粒运动分析

Analysis of Particle Movement in Liquid Injected Fluidized Bed Based on PIV

为了考察反应器中物料的流动模式,为反应器优化提供参考,利用粒子图像测速技术(PIV)对注液气固流化床内颗粒运动的湍流场进行了测量。统计了颗粒在边壁区和中心区的运动速度,并利用本征正交分解方法(POD)对获得流场进行处理,提取场内相干结构并分析注液对湍流场造成的影响。运动速度统计结果表明,注入少量液体时颗粒运动变得更加剧烈,由于侧壁影响,颗粒在边壁区速度波动较中心区更大。POD分解得到的空间模态图表明,流场中大尺度相干结构主要出现在边壁区,相干结构呈波纹状并随液体的逐渐加入向小尺度结构发展。所以,少量液体的注入增加了流化床内颗粒运动,对于提高反应器效率有利。

In order to investigate the flow pattern of materials in the reactor and provide information for reactor optimization, particle image velocimetry (PIV) was used to carefully measure the turbulent flow field of particles in a liquid injected gas-solid fluidized bed. The velocity of particles in the sidewall area and central area was statistically analyzed, the proper orthogonal decomposition (POD) was used to decompose and reconstruct the flow field, the coherent structure was extracted and the effect of the injected liquid on the turbulent flow field was analyzed. The statistical results of velocity showed that the particle movement became more intense when small amount of liquid was injected, and the velocity fluctuation of particles in the sidewall area was larger than that in the center region because of the side wall effect. The spatial modal diagrams obtained by POD showed that the large-scale coherent structure mainly appeared in the sidewall area, and the coherent structure was corrugated and developed to the small-scale structure with the gradual addition of liquids. Therefore, the injection of a small amount of liquid promotes the particle movement in the fluidized bed, which is beneficial to improve the efficiency of the reactor.