CFD simulation of liquid distribution in different distributors in medium-low temperature coal tar hydrogenation reactor

doi:10.16085/j.issn.1000-6613.2022-1872

Abstract

Abstract:

Medium-low temperature coal tar (LTCT) is a kind of heavy oil with high density and high viscosity. Hydrotreating is an important means for clean utilization of LTCT, which is mainly completed in trickle bed reactor (TBR). As an important component of TBR, the gas-liquid distributor affects the performance of catalyst bed in the reactor. In this paper, a computational fluid dynamics (CFD) model based on Euler-Euler method was established, and the model was verified according to the cold model experiment results reported in the literature. The flow of LTCT and hydrogen in four kinds of distributors (bubble cap, multiport chimney, slot chimney and vapor-lift tube) was simulated. The liquid distribution, flow behavior and pressure drop of the distributors were compared and analyzed. In addition, the concept of liquid maldistribution factor (M_f) was introduced to quantitatively evaluate the gas-liquid distribution effect of four kinds of distributors. The results showed that the liquid phase coverage of LTCT was the widest after passing through the bubble cap. When the bubble cap was at y=-200mm section, the M_f value was 0.13, the distribution effect was the best, and the gas-liquid two-phase flow concentration phenomenon was not serious.

Key words: medium-low temperature coal tar, trickle bed reactor, gas-liquid distributor, two-phase flow, computational fluid dynamics (CFD), simulation

摘要：

中低温煤焦油（LTCT）是一种高密度、高黏度的重质油品，加氢处理是对其清洁化利用的重要手段，其过程主要在滴流床反应器（TBR）内完成。气液分配器作为TBR中的重要部件，影响着反应器中催化剂床层的表现。本文建立了基于Euler-Euler方法的计算流体力学（CFD）模型，并根据已报道的文献冷模实验结果完成模型验证，对LTCT和氢气在4种分配器（泡罩型、多孔烟囱型、齿缝烟囱型和气提管型）中的流动进行了模拟，对比分析了分配器液相的分布、流动行为以及进出口压降；并且引入液体分布不均匀度（M_f）概念，对4种分配器的气液分配效果进行了定量评价。结果表明，LTCT通过泡罩型分配器后的液相覆盖范围最广；泡罩型分配器在y=-200mm截面处M_f为0.13，分配效果最好，且气液两相流集中现象不严重。

关键词: 中低温煤焦油, 滴流床反应器, 分配器, 两相流动, 计算流体力学, 模拟

CLC Number:

TQ051.1

LUO Cheng, FAN Xiaoyong, ZHU Yonghong, TIAN Feng, CUI Louwei, DU Chongpeng, WANG Feili, LI Dong, ZHENG Hua’an. CFD simulation of liquid distribution in different distributors in medium-low temperature coal tar hydrogenation reactor[J]. Chemical Industry and Engineering Progress, 2023, 42(9): 4538-4549.

罗成, 范晓勇, 朱永红, 田丰, 崔楼伟, 杜崇鹏, 王飞利, 李冬, 郑化安. 中低温煤焦油加氢反应器不同分配器中液体分布的CFD模拟[J]. 化工进展, 2023, 42(9): 4538-4549.

Figures/Tables 15

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参数	数值
参数	实验1	实验2	实验3	实验4	实验5
空气（气相）流量/m³·h^-1	3.0	5.0	7.0	9.0	11.0
水（液相）流量/m³·h^-1	0.35	0.35	0.35	0.35	0.35
入口温度/K	298
操作压力/MPa	0.101
气相密度/kg·m^-3	1.30×10^-3
气相黏度/mPa·s	17.9×10^-3
液体密度/kg·m^-3	998
液相黏度/mPa·s	2.98
表面张力系数/N·m^-1	7.2×10^-2
重力加速度/m·s^-2	9.81

参数	数值
参数	实验1	实验2	实验3	实验4	实验5
空气（气相）流量/m³·h^-1	3.0	5.0	7.0	9.0	11.0
水（液相）流量/m³·h^-1	0.35	0.35	0.35	0.35	0.35
入口温度/K	298
操作压力/MPa	0.101
气相密度/kg·m^-3	1.30×10^-3
气相黏度/mPa·s	17.9×10^-3
液体密度/kg·m^-3	998
液相黏度/mPa·s	2.98
表面张力系数/N·m^-1	7.2×10^-2
重力加速度/m·s^-2	9.81

水（液相）流量 /m³·h^-1	空气（气相）流量 /m³·h^-1	进出口压降/Pa		相对误差 /%
水（液相）流量 /m³·h^-1	空气（气相）流量 /m³·h^-1	实验值^[15]	模拟值	相对误差 /%
3.0	0.35	654	623	4.7
5.0	0.35	667	637	4.4
7.0	0.35	683	652	4.9
9.0	0.35	769	735	4.4
11.0	0.35	856	824	3.7

水（液相）流量 /m³·h^-1	空气（气相）流量 /m³·h^-1	进出口压降/Pa		相对误差 /%
水（液相）流量 /m³·h^-1	空气（气相）流量 /m³·h^-1	实验值^[15]	模拟值	相对误差 /%
3.0	0.35	654	623	4.7
5.0	0.35	667	637	4.4
7.0	0.35	683	652	4.9
9.0	0.35	769	735	4.4
11.0	0.35	856	824	3.7

参数	数值
氢气（气相）流量/m³·h^-1	41.5
LTCT（液相）流量/m³·h^-1	2.90
入口温度/K	503
操作压力/MPa	14.0
气相密度/kg·m^-3	6.29
气相黏度/mPa·s	1.27×10^-2
液体密度/kg·m^-3	993
液相黏度/mPa·s	62.7
表面张力系数/N·m^-1	3.20×10^-2
重力加速度/m·s^-2	9.81