化工学报 ›› 2022, Vol. 73 ›› Issue (6): 2708-2721.DOI: 10.11949/0438-1157.20220399
收稿日期:
2022-03-22
修回日期:
2022-05-11
出版日期:
2022-06-05
发布日期:
2022-06-30
作者简介:
石孝刚(1987—)男,博士,副教授,基金资助:
Xiaogang SHI(),Chengxiu WANG,Jinsen GAO,Xingying LAN()
Received:
2022-03-22
Revised:
2022-05-11
Online:
2022-06-05
Published:
2022-06-30
摘要:
提升管反应器存在典型的颗粒聚团介尺度结构,其分布特性对气固流动、反应有重要影响,对介尺度结构影响规律进行分析有助于为反应器的设计与优化操作提供基础信息。采用基于能量最小多尺度(EMMS)方法的曳力模型建立了提升管气固两相流动模型,考虑了颗粒聚团对气固相间动量传递的影响。此外,进一步通过考虑颗粒聚团的存在以及颗粒聚团的非均匀性对化学反应的影响,提出了描述介尺度结构对反应速率影响的修正因子,与气固流动模型进行耦合,建立了基于介尺度结构的流动-反应综合数学模型,并进行了模型验证。进一步应用该模型,对工业催化裂化提升管反应器的流动-反应特性进行了模拟分析。结果表明,该模型可以合理描述提升管气固相互作用,能够预测出壁面附近存在较多介尺度结构的分布特性,由于聚团的存在使得重油组分难以与催化剂充分接触,生成汽柴油的反应速率较低,转化较慢,聚团的分布特性导致靠近边壁处的重油组分浓度较高,汽柴油组分浓度较低;汽柴油在聚团内部的流动阻力较大,在聚团内发生过量的二次反应生成较多焦炭,导致壁面处焦炭浓度较高。与传统基于平均化而未考虑聚团影响的模型相比,基于介尺度结构的模型所预测的汽油收率最佳值与工业实际相接近。因此,基于介尺度结构的流动-反应综合数学模型可以合理描述提升管内进行的流动-反应耦合特性,并能揭示介尺度结构对催化裂化反应过程的影响,有望为工业提升管装置反应终止剂技术的开发提供重要的基础信息。
中图分类号:
石孝刚, 王成秀, 高金森, 蓝兴英. 提升管反应器介尺度结构影响规律的数值模拟研究[J]. 化工学报, 2022, 73(6): 2708-2721.
Xiaogang SHI, Chengxiu WANG, Jinsen GAO, Xingying LAN. Numerical simulation study on influence of mesoscale structure in riser reactor[J]. CIESC Journal, 2022, 73(6): 2708-2721.
项 目 | 方程表达式 |
---|---|
曳力模型系数β | |
曳力系数修正因子 | |
εg>0.997 | |
0.997>εg>0.99 | |
0.99>εg>0.545 | |
0.545>εg>0.4 |
表1 EMMS曳力模型表达式
Table 1 EMMS model equations
项 目 | 方程表达式 |
---|---|
曳力模型系数β | |
曳力系数修正因子 | |
εg>0.997 | |
0.997>εg>0.99 | |
0.99>εg>0.545 | |
0.545>εg>0.4 |
空隙率 | 气速/(m/s) | 短轴 | 长短轴比 | 倾角/(°) | ||
---|---|---|---|---|---|---|
一次反应Hc,1 | 二次反应Hc,2 | |||||
0.83 | 0.1 | 0.67 | 1 | 0 | 0.1560 | 0.8900 |
0.83 | 0.5 | 0.67 | 1 | 0 | 0.1930 | 0.9589 |
0.83 | 1 | 0.67 | 1 | 0 | 0.2107 | 0.9937 |
0.83 | 1.5 | 0.67 | 1 | 0 | 0.2228 | 1.0165 |
0.83 | 2 | 0.67 | 1 | 0 | 0.2325 | 1.0339 |
0.83 | 2.5 | 0.67 | 1 | 0 | 0.2409 | 1.0484 |
0.83 | 3 | 0.67 | 1 | 0 | 0.2485 | 1.0609 |
0.90 | 5 | 0.5 | 1 | 0 | 0.4511 | 1.1105 |
0.90 | 7.5 | 0.5 | 1 | 0 | 0.5242 | 1.1119 |
0.90 | 10 | 0.5 | 1 | 0 | 0.5828 | 1.1073 |
0.96 | 0.5 | 0.5 | 1 | 0 | 0.5638 | 1.0498 |
0.96 | 1 | 0.5 | 1 | 0 | 0.6299 | 1.0522 |
… | … | … | … | … | … | … |
表2 颗粒聚团上的平均反应速率和单颗粒上的反应速率的比值
Table 2 Ratio of reaction rate on cluster to that on single particle
空隙率 | 气速/(m/s) | 短轴 | 长短轴比 | 倾角/(°) | ||
---|---|---|---|---|---|---|
一次反应Hc,1 | 二次反应Hc,2 | |||||
0.83 | 0.1 | 0.67 | 1 | 0 | 0.1560 | 0.8900 |
0.83 | 0.5 | 0.67 | 1 | 0 | 0.1930 | 0.9589 |
0.83 | 1 | 0.67 | 1 | 0 | 0.2107 | 0.9937 |
0.83 | 1.5 | 0.67 | 1 | 0 | 0.2228 | 1.0165 |
0.83 | 2 | 0.67 | 1 | 0 | 0.2325 | 1.0339 |
0.83 | 2.5 | 0.67 | 1 | 0 | 0.2409 | 1.0484 |
0.83 | 3 | 0.67 | 1 | 0 | 0.2485 | 1.0609 |
0.90 | 5 | 0.5 | 1 | 0 | 0.4511 | 1.1105 |
0.90 | 7.5 | 0.5 | 1 | 0 | 0.5242 | 1.1119 |
0.90 | 10 | 0.5 | 1 | 0 | 0.5828 | 1.1073 |
0.96 | 0.5 | 0.5 | 1 | 0 | 0.5638 | 1.0498 |
0.96 | 1 | 0.5 | 1 | 0 | 0.6299 | 1.0522 |
… | … | … | … | … | … | … |
Hr表达式 | εg范围 |
---|---|
[0.4,0.4162] | |
[0.4162,0.4257] | |
[0.4257,0.5457] | |
[0.5457,1.0] |
表3 非均匀的颗粒聚团对化学反应速率的影响因子表达式[19]
Table 3 Correlation for influence factor of heterogeneous cluster on reaction rate[19]
Hr表达式 | εg范围 |
---|---|
[0.4,0.4162] | |
[0.4162,0.4257] | |
[0.4257,0.5457] | |
[0.5457,1.0] |
参数 | 数 值 |
---|---|
提升管直径D/m | 0.076 |
提升管高度h/m | 10 |
颗粒粒径dp/μm | 76 |
颗粒密度ρp/(kg/m3) | 1780 |
气体密度ρg/(kg/m3) | 1.1795 |
表4 模拟对象尺寸和物性
Table 4 Size of simulation set-up and properties of materials
参数 | 数 值 |
---|---|
提升管直径D/m | 0.076 |
提升管高度h/m | 10 |
颗粒粒径dp/μm | 76 |
颗粒密度ρp/(kg/m3) | 1780 |
气体密度ρg/(kg/m3) | 1.1795 |
图2 提升管内臭氧浓度的轴向分布(Ug=9 m/s,虚线代表基于平均化的模型,实线代表基于介尺度结构的模型)
Fig.2 Axial distribution of ozone concentration in riser (Ug=9 m/s, dash line is for homogeneous model while solid line for mesoscale model)
图3 提升管内臭氧浓度的径向分布(Ug=9 m/s,虚线代表基于平均化的模型,实线代表基于介尺度结构的模型)
Fig.3 Radial distribution of ozone concentration in riser(Ug=9 m/s, dash line is for homogeneous model while solid line for mesoscale model)
参 数 | 数值 |
---|---|
原料油质量流率/(t/h) | 152 |
雾化蒸汽质量流率/(t/h) | 9.6 |
预提升蒸汽质量流率/(kg/h) | 4070 |
催化剂循环量/(t/h) | 1156 |
剂油比 | 7 |
物料混合温度/℃ | 550 |
表5 工业提升管反应器工艺参数
Table 5 Simulation parameter for industrial FCC riser
参 数 | 数值 |
---|---|
原料油质量流率/(t/h) | 152 |
雾化蒸汽质量流率/(t/h) | 9.6 |
预提升蒸汽质量流率/(kg/h) | 4070 |
催化剂循环量/(t/h) | 1156 |
剂油比 | 7 |
物料混合温度/℃ | 550 |
图14 提升管高度方向上各产物产率变化(实线为基于介尺度结构的模型,虚线为基于平均化的模型)
Fig.14 Yield of different components along riser height (solid line for mesoscale model, and dash line for homogeneous model)
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