化工学报 ›› 2019, Vol. 70 ›› Issue (5): 1682-1692.DOI: 10.11949/j.issn.0438-1157.20190016
佟颖1,2,Ahmad Nouman1,鲁波娜1,2,3(),王维1,2
收稿日期:
2019-01-07
修回日期:
2019-02-22
出版日期:
2019-05-05
发布日期:
2019-05-05
通讯作者:
鲁波娜
作者简介:
鲁波娜(1979—),女,博士,副研究员,<email>bnlu@ipe.ac.cn</email>
基金资助:
TONG Ying1,2,AHMAD Nouman1,LU Bona1,2,3(),WANG Wei1,2
Received:
2019-01-07
Revised:
2019-02-22
Online:
2019-05-05
Published:
2019-05-05
Contact:
LU Bona
摘要:
双分散气固鼓泡流化床中颗粒通常具有不同粒径或密度,导致产生颗粒偏析等现象,影响传递和反应行为。颗粒分离和混合与气泡运动密不可分,其中相间曳力起关键作用。最近Ahmad等提出了一种基于气泡结构的双分散介尺度曳力模型,能成功预测双分散鼓泡流化床的床层膨胀系数。本研究耦合该曳力模型与连续介质方法,模拟了两种不同的双分散鼓泡流化床,通过分析不同流化状态下的气泡运动、颗粒浓度比的轴向分布等参数,进一步检验模型的适用性。研究表明,当双分散颗粒处于完全流化状态时,耦合双分散介尺度曳力模型可合理预测不同颗粒的分离现象;而其处于过渡流化状态时,新曳力模型和传统模型均无法获得合理结果,此时调节固固曳力可改进模拟结果。
中图分类号:
佟颖, Ahmad Nouman, 鲁波娜, 王维. 基于EMMS介尺度模型的双分散鼓泡流化床的模拟[J]. 化工学报, 2019, 70(5): 1682-1692.
TONG Ying, AHMAD Nouman, LU Bona, WANG Wei. Numerical investigation of bubbling fluidized bed with binary particle mixture using EMMS mesoscale drag model[J]. CIESC Journal, 2019, 70(5): 1682-1692.
参数 | 石英砂 (silica sand) | 玻璃珠 (glass bead) | 硅胶 (silica gel) |
---|---|---|---|
系统1 | √ (浮料) | √ (沉料) | |
系统2 | √ (沉料) | √ (浮料) | |
Sauter平均粒径/μm | 125 | 500 | 375 |
球形度 | | 1 | |
密度/(kg·m-3) | 2600 | 2540 | 600 |
Geldart分类 | B | B | A-B |
终端速度/(m·s-1) | 0.80 | 4.10 | 1.25 |
最小流态化速度/(m·s-1) | 0.022 | 0.23 | 0.032 |
表1 两个双分散流态化系统的物性参数
Table 1 Material properties used in two systems of binary particle mixtures
参数 | 石英砂 (silica sand) | 玻璃珠 (glass bead) | 硅胶 (silica gel) |
---|---|---|---|
系统1 | √ (浮料) | √ (沉料) | |
系统2 | √ (沉料) | √ (浮料) | |
Sauter平均粒径/μm | 125 | 500 | 375 |
球形度 | | 1 | |
密度/(kg·m-3) | 2600 | 2540 | 600 |
Geldart分类 | B | B | A-B |
终端速度/(m·s-1) | 0.80 | 4.10 | 1.25 |
最小流态化速度/(m·s-1) | 0.022 | 0.23 | 0.032 |
操作参数 | 系统1 | 系统2 |
---|---|---|
颗粒堆料量/kg | 2.8 | 2.85 |
沉料的初始体积比 | 0.5 | 0.2 |
初始堆料高度/m | 0.135 | 0.4 |
表观气速/(m·s-1) | 0.07,0.09 | 0.032,0.152 |
表2 两个双分散流态化系统的操作条件
Table 2 Operating conditions for two systems of binary particle mixtures
操作参数 | 系统1 | 系统2 |
---|---|---|
颗粒堆料量/kg | 2.8 | 2.85 |
沉料的初始体积比 | 0.5 | 0.2 |
初始堆料高度/m | 0.135 | 0.4 |
表观气速/(m·s-1) | 0.07,0.09 | 0.032,0.152 |
Parameter | Specification |
---|---|
transient formulation | second-order implicit |
pressure-velocity coupling | phase coupled SIMPLE |
gradient discretization | green-Gauss cell based |
momentum discretization | second-order upwind |
volume fraction discretization | quick |
granular temperature | algebraic |
granular viscosity | Syamlal-O’Brien |
granular bulk viscosity | Lun-et-al |
frictional viscosity | Schaeffer |
angle of internal friction | 30 |
frictional pressure | based-ktgf |
frictional modulus | derived |
friction packing limit | 0.5 |
solid pressure | Lun-et-al |
radial distribution | Ma-Ahmadi |
elasticity modulus | derived |
gas-solid drag | binary EMMS-bubbling or Gidaspow model |
solid-solid interaction | Syamlal-O’Brien symmetric model |
packing limit | 0.62 |
restitution coefficient | 0.9 |
physical time step | 0.0001 s |
表3 模拟的具体设置
Table 3 Simulation settings
Parameter | Specification |
---|---|
transient formulation | second-order implicit |
pressure-velocity coupling | phase coupled SIMPLE |
gradient discretization | green-Gauss cell based |
momentum discretization | second-order upwind |
volume fraction discretization | quick |
granular temperature | algebraic |
granular viscosity | Syamlal-O’Brien |
granular bulk viscosity | Lun-et-al |
frictional viscosity | Schaeffer |
angle of internal friction | 30 |
frictional pressure | based-ktgf |
frictional modulus | derived |
friction packing limit | 0.5 |
solid pressure | Lun-et-al |
radial distribution | Ma-Ahmadi |
elasticity modulus | derived |
gas-solid drag | binary EMMS-bubbling or Gidaspow model |
solid-solid interaction | Syamlal-O’Brien symmetric model |
packing limit | 0.62 |
restitution coefficient | 0.9 |
physical time step | 0.0001 s |
网格尺寸 | 全床平均气含率 | H=0.8对应的X 2 |
---|---|---|
5 mm ×5 mm | 0.8063 | 0.4460 |
3 mm ×3 mm | 0.8077 | 0.4572 |
2 mm ×2 mm | 0.8081 | 0.4610 |
表4 不同网格下的全床平均气含率和某截面高度的X 2
Table 4 Average gas volume fraction and X 2 at height of 0.8 under three grid resolutions
网格尺寸 | 全床平均气含率 | H=0.8对应的X 2 |
---|---|---|
5 mm ×5 mm | 0.8063 | 0.4460 |
3 mm ×3 mm | 0.8077 | 0.4572 |
2 mm ×2 mm | 0.8081 | 0.4610 |
图8 采用不同气固曳力模型的X 2轴向分布(系统1:U g=0.07 m·s-1,K=0.005)
Fig.8 Comparison of axial profiles of volume ratio of jetsam using different gas-solid drag models(system 1: U g=0.07 m·s-1, K=0.005)
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