基于CFD模拟的催化裂化沉降器跑剂异常诊断

doi:10.16085/j.issn.1000-6613.2024-1681

摘要/Abstract

摘要：

沉降器内部异常的气固两相流动状态会影响装置的分离能力，造成催化剂大量跑损，严重影响装置长周期安全稳定的运行。本文采用计算流体力学（CFD）模拟的方法考察装置原料处理量变化、催化剂循环量变化以及分离系统出现磨损穿孔、堵塞等机械故障时装置内部气固两相流动、传热和分离过程，并建立一种沉降器跑剂异常诊断的方法。研究结果表明，沉降器操作参数改变时装置内气固含量发生变化，顶旋入口条件偏离正常运行范围时，装置会出现阵发性的跑剂异常；沉降器发生机械故障时，内部出现窜气、短路流等异常气固流化状态，进而影响装置内速度、温度和压力分布，导致顶旋的分离能力急剧降低，装置出现持续性的跑剂异常。基于沉降器跑剂机理和数值模拟结果，建立了针对沉降器操作参数改变和设备机械故障跑剂的诊断方法，并通过工业实例证实了该方法的准确性。本文为沉降器跑剂问题的预防及应急处理提供理论支持，有助于催化裂化装置高效运行。

关键词: 催化裂化沉降器, 操作参数, 设备机械故障, 跑剂, 数值模拟, 异常诊断

Abstract:

Abnormal gas-solid two-phase flow states inside the disengager impair the unit's separation capacity and cause substantial catalyst loss. Abnormal operating conditions of the catalyst loss severely affect the long-term safe and stable operation of the unit. This study employs numerical simulation to investigate the variation laws of gas-solid two-phase flow, heat transfer, and separation processes inside the disengager under conditions of changes in the oil gas flow, changes in catalyst circulation flow, and mechanical failures in the separation system. Additionally, a method for diagnosing abnormal catalyst loss in the disengager is established. The results show that changes in the disengager's operating parameters alter the internal gas-solid content. When the inlet conditions of the top cyclone deviate from the normal operating range, the disengager exhibits intermittent abnormal catalyst loss. Mechanical failures in the disengager cause abnormal gas-solid fluidization states such as gas in-leakage and short-circuit flows, which further disturb the velocity, temperature, and pressure distributions inside. This disruption sharply reduces the top cyclone's separation capacity, leading to sustained abnormal catalyst loss.Based on the catalyst loss mechanism and numerical simulation results, a diagnostic method is established for catalyst loss caused by changes of the operating parameters and equipment mechanical failure. Its accuracy is validated through industrial cases. This study provides theoretical support for preventing and handling catalyst loss in the disengager, facilitating the efficient operation of fluidized catalytic cracking units.

Key words: fluidized catalytic cracking (FCC) disengager, operating parameter, mechanical failure of equipment, catalyst loss, numerical simulation, abnormal diagnosis

中图分类号:

TE624.41

李增, 赵云鹏, 李宇慧, 柳楠, 朱春梦, 石孝刚, 高金森, 蓝兴英. 基于CFD模拟的催化裂化沉降器跑剂异常诊断[J]. 化工进展, 2025, 44(8): 4430-4442.

LI Zeng, ZHAO Yunpeng, LI Yuhui, LIU Nan, ZHU Chunmeng, SHI Xiaogang, GAO Jinsen, LAN Xingying. Abnormal diagnosis of catalyst loss for FCC disengager based on CFD simulation[J]. Chemical Industry and Engineering Progress, 2025, 44(8): 4430-4442.

图/表 15

图1 基于数值模拟的沉降器跑剂异常诊断模型

图2 沉降器几何模型及计算网格

表1 物性参数

物质	密度/kg·m^-3	比热容/J·kg^-1·K^-1	黏度/Pa·s
水蒸气	2.54	2.2×10³	2.858×10^-5
混合油气	4.42	3.2×10³	1.741×10^-5
催化剂	1.5×10³	1.1×10³	—

图3 沉降器边界条件示意图

表2 模拟参数

参数	数值
原料油流量/kg·s^-1	124.2
预提升蒸汽流量/kg·s^-1	7.3
汽提蒸汽流量/kg·s^-1	1.9
防焦蒸汽流量/kg·s^-1	1.7
剂油比	6.0
混合油气温度/℃	512.0
顶旋出口压力/kPa	253.0
待生催化剂出口压力/kPa	415.0

表3 模拟数据与工业数据对比

项目	快分出口油气线速度/m·s^-1	顶旋入口油气线速度/m·s^-1	沉降器出口压力/kPa	汽提段压降/kPa	稀相空间温度/℃	催化剂跑损量/kg·s^-1
模拟数据	20.6	22.3	253.1	74.5	443.0	0.025
工业数据	18.8	20.3	253.7	76.6	436.5	0.023
相对误差	9.6%	9.9%	0.2%	2.8%	1.5%	8.7%

图4 不同原料处理量对特征参数变化的影响

图5 不同催化剂循环量对特征参数变化的影响

图6 设备机械故障对特征参数变化的影响

图7 旋流快分头器壁穿孔时沉降器内各物理场分布

图8 顶旋壁面穿孔时沉降器内各物理场分布

图9 顶旋翼阀窜气时沉降器内各物理场分布

图10 顶旋料腿堵塞时沉降器内各物理场分布

图11 沉降器典型跑剂异常工况诊断流程

图12 沉降器跑剂异常期间历史运行数据

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