Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs

doi:10.1016/j.cjche.2016.12.009

›› 2017, Vol. 25 ›› Issue (7): 848-861.DOI: 10.1016/j.cjche.2016.12.009

• Fluid Dynamics and Transport Phenomena • 上一篇下一篇

Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs

Asheesh Nautiyal, Chien-Song Chyang, Pin-Wei Li, Hsin-Yung Hou

Department of Chemical Engineering, Chung Yuan Christian University, Taoyuan 320, Taiwan, China

收稿日期:2016-06-22 修回日期:2016-12-08 出版日期:2017-07-28 发布日期:2017-08-17
通讯作者: Chien-Song Chyang,E-mail address:cschyang@cycu.edu.tw

Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs

Asheesh Nautiyal, Chien-Song Chyang, Pin-Wei Li, Hsin-Yung Hou

Department of Chemical Engineering, Chung Yuan Christian University, Taoyuan 320, Taiwan, China

Received:2016-06-22 Revised:2016-12-08 Online:2017-07-28 Published:2017-08-17

摘要/Abstract

摘要： In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, D_x and D_y, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted. Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that D_x and D_y are nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on D_x is minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor.

关键词: Gas dispersion coefficient, Horizontal mixing, Wall effect, Surface modeling

Abstract: In a rectangular fluidized bed combustor, the tracer gas is injected continuously into the bed from a point source at the center of the distributor plate. In this study, a general governing equation is formulated for tracer gas dispersion in the bed. An analytical solution is derived to estimate the dispersion coefficients, D_x and D_y, in a horizontal plane. The concentration profiles at different sampling heights with various gas velocities are plotted. Subsequently, to estimate the dispersion coefficients, surface fitting of the obtained analytical solution to the experimental data is performed. The dispersion coefficients obtained from this model are compared with those of a conventional model. Additionally, the effect of walls, bed height and gas injection rate on the dispersion coefficients in a horizontal plane is investigated, and the effect of distributor design on the dispersion coefficients in a horizontal plane is investigated with different tracer positions. It is found that D_x and D_y are nearly equivalent at a lower tracer gas ratio of the injected gas to the total gas flow rate. It is also demonstrated that the effect of bed height on D_x is minor. This model is also able to estimate the dispersion coefficients in the case of a multihorizontal nozzle distributor.

Key words: Gas dispersion coefficient, Horizontal mixing, Wall effect, Surface modeling

Asheesh Nautiyal, Chien-Song Chyang, Pin-Wei Li, Hsin-Yung Hou. Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs[J]. , 2017, 25(7): 848-861.

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Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs

Horizontal gas mixing in rectangular fluidized bed:A novel method for gas dispersion coefficients in various conditions and distributor designs

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