Diffusion coefficient of solid particles in turbulent fluidized bed

doi:10.11949/j.issn.0438-1157.20151492

Abstract

Abstract:

Based on particle image velocity (PIV) technology and particle diffusion law, the diffusion coefficient of SAPO-34 catalyst particles in turbulent fluidized bed for methanol to olefins (MTO) was studied. A two dimensional transparent glass fluidized bed reactor was used to study the particle diffusion coefficient as functions of operating gas velocity and particle size. The motion of SAPO-34 particles was recorded by high speed camera, based on which both longitudinal and lateral velocities were calculated via image processing technology, hence the diffusion coefficient was obtained according to particle diffusion law. It showed that both longitudinal and lateral diffusion coefficient of SAPO-34 particles (Geldart A) increased with operating gas velocity. The longitudinal diffusion coefficient ranged from 10^-3 m²·s^-1 to 10^-2 m²·s^-1, and the lateral diffusion coefficient from 10^-1 m²·s^-1 to 10^-2 m²·s^-1. In addition, under the same fluidization operating gas velocity, the particles with smaller particle size possessed larger diffusion coefficient than those with larger one. It is of significance for the research related to the motion law of particles in turbulent fluidized bed.

Key words: turbulence, fluidization, PIV, diffusion coefficient, MTO

摘要：

将高速摄影及基于互相关原理的图像处理技术与颗粒扩散规律的研究进行结合,对湍动流化床中甲醇制烯烃催化剂SAPO-34颗粒的扩散系数进行了实验研究。实验表明,对于Geldart A类的SAPO-34颗粒,颗粒纵向扩散系数在10^-2～10^-1 m²·s^-1量级之间,横向扩散系数在10^-3～10^-2 m²·s^-1量级之间,两者均随流化风速的上升而增大。另外,在相同的流化风速下,粒径较小的颗粒具有更大的扩散系数。该结果对湍动床颗粒运动规律的研究有一定意义。

关键词: 湍动, 流态化, 粒子图像测速, 扩散系数, 甲醇制烯烃

CLC Number:

TQ13

ZHOU Bihui, ZHAO Ming, LIANG Junyu, LU Yong, XIAO Rui. Diffusion coefficient of solid particles in turbulent fluidized bed[J]. CIESC Journal, 2016, 67(5): 1741-1747.

周弼辉, 赵明, 梁俊宇, 陆勇, 肖睿. 湍动流化床内固体颗粒扩散系数[J]. 化工学报, 2016, 67(5): 1741-1747.

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