Record number :
1704995
Title of article :
Numerical studies of solid–solid mixing behaviors in a downer reactor for coal pyrolysis
Author/Authors :
Cheng، نويسنده , , Yongpan and Zhang، نويسنده , , Wenbiao and Guan، نويسنده , , Guoqing and Fushimi، نويسنده , , Chihiro and Tsutsumi، نويسنده , , Atsushi and Wang، نويسنده , , Chi-Hwa، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2014
Pages :
11
From page :
722
To page :
732
Abstract :
A downer reactor is ideal for fast pyrolysis during coal gasification as solids holdup distributions and residence time distribution in the reactor are fairly uniform and residence time is short. Because pyrolysis is a rapid reaction, in the downer solid–solid mixing is critical to promote pyrolysis reaction. Thus, solid–solid mixing in the downer was studied through numerical modeling in this study. An Eulerian–Lagrangian method was applied and implemented by combining Computational Fluid Dynamics and Discrete Element Method (CFD–DEM). The heat carrying media of silica sand was modeled to flow from the top of the downer while coal particles were introduced through two lateral nozzles in normal and tangential arrangements. Numerical results showed that tangential arrangement had lower solids holdups while higher particle velocities than normal arrangement. Mixing among binary solid particles was poor at the entrance of downer. The extent of mixing increased rapidly and approached an almost constant value in the downstream regions of the downer. High air velocity and small solid particle size could lead to better mixing for both normal and tangential arrangements. But tangential arrangement had better mixing of binary solid particles than normal arrangement, and when the particle sizes were reduced from 2 to 1 mm, the influence of nozzle arrangement was reduced.
Keywords :
Mathematical Modeling , Discrete element method , Multiphase flow , Downer , Mixing
Journal title :
Powder Technology
Journal title :
Powder Technology
Serial Year :
2014
Link To Document :
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