Multi-objective optimization of FCC separation system based on improved NSGA-Ⅱ

doi:10.11949/0438-1157.20201335

Abstract

Abstract:

The process simulation software HYSYS was used to simulate the whole process of a 650000 t/a heavy oil catalytic cracking unit in a refinery. An improved non-dominated sorting genetic algorithm (NSGA-Ⅱ) was used for the multi-objective optimization of the FCC separation system, with the maximum yield of target products (gasoline + LPG) and minimum energy consumption of separation system as the optimization objectives. A meticulous multi-objective optimization method was established through the optimal selection of decision variables, the study of optimal algorithm parameters (including population, P_c, P_m adaptive strategy, and generation), and the optimal decision. The optimization results showed that the yield of the target products (gasoline + LPG) increased by 4.32 percentage points and the energy consumption of the separation system decreased by 16.88%. The optimization results provided important data support and optimization suggestions for the optimization of the operating variables of the FCC separation system.

Key words: FCC, separation system, NSGA-Ⅱ, multi-objective optimization, energy conservation

摘要：

应用流程模拟软件HYSYS对某炼厂65万吨/年重油催化裂化装置进行全流程模拟。以最大目的产品（汽油+液化气）收率与最小分离系统能耗为优化目标，采用改进的非支配排序遗传算法（NSGA-Ⅱ）对FCC分离系统进行多目标优化。通过对决策变量的择优选取、最优算法参数的研究（包括种群规模、P_c与P_m自适应策略、遗传代数）、最优点的决策建立了一套缜密的多目标优化方法。优化结果显示，目的产品（汽油+液化气）收率提升4.32个百分点，分离系统能耗降低16.88%，为FCC分离系统的操作变量优化提供了重要的数据支持与优化建议。

关键词: 催化裂化, 分离系统, NSGA-Ⅱ, 多目标优化, 节能

CLC Number:

TE 624

WEI Bin, ZHOU Xin, WANG Yaowei, GUO Zhenlian, CHEN Xiaobo, LIU Yibin, YANG Chaohe. Multi-objective optimization of FCC separation system based on improved NSGA-Ⅱ[J]. CIESC Journal, 2021, 72(5): 2735-2744.

魏彬, 周鑫, 王耀伟, 郭振莲, 陈小博, 刘熠斌, 杨朝合. 基于改进NSGA-Ⅱ算法的FCC分离系统多目标优化[J]. 化工学报, 2021, 72(5): 2735-2744.

Figures/Tables 18

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校准参数	数值
activity on pathways to C lump	0.8577
activity on pathways to G lump	0.2776
activity on pathways to L lump	1.322
metals coke activity	0.00886
catalyst deactivation factor	0.7987
catalyst surface area parameter	-10.72
effluent per mass of catalyst into stripper	73.27
stripper parameter	3.066
heat of cracking parameter	0.0029
H to C ratio for coke	0.7468
coke burn activity	15.43
kinetic coke activity factor	0.01287

校准参数	数值
activity on pathways to C lump	0.8577
activity on pathways to G lump	0.2776
activity on pathways to L lump	1.322
metals coke activity	0.00886
catalyst deactivation factor	0.7987
catalyst surface area parameter	-10.72
effluent per mass of catalyst into stripper	73.27
stripper parameter	3.066
heat of cracking parameter	0.0029
H to C ratio for coke	0.7468
coke burn activity	15.43
kinetic coke activity factor	0.01287

参数	标定值	模拟值	相对误差
主分馏塔塔顶/底温度/℃	117/345	118.1/347.3	0.94%/0.67%
吸收塔塔顶/底温度/℃	37/45	34.6/44.3	6.49%/1.56%
解吸塔塔顶/底温度/℃	59/119	56.6/116.4	4.07%/2.18%
再吸收塔塔顶/底温度/℃	29/43	26.3/40.6	9.31%/5.59%
稳定塔塔顶/底温度/℃	57/175	60.6/180.7	6.31%/2.11%
富气流量/(t/h)	15.8	15.24	3.54%
粗汽油流量/(t/h)	26.2	26.77	2.18%
粗汽油干点/℃	199.3	201.5	1.10%
轻柴油95%馏出点/℃	358.7	363.4	1.31%

参数	标定值	模拟值	相对误差
主分馏塔塔顶/底温度/℃	117/345	118.1/347.3	0.94%/0.67%
吸收塔塔顶/底温度/℃	37/45	34.6/44.3	6.49%/1.56%
解吸塔塔顶/底温度/℃	59/119	56.6/116.4	4.07%/2.18%
再吸收塔塔顶/底温度/℃	29/43	26.3/40.6	9.31%/5.59%
稳定塔塔顶/底温度/℃	57/175	60.6/180.7	6.31%/2.11%
富气流量/(t/h)	15.8	15.24	3.54%
粗汽油流量/(t/h)	26.2	26.77	2.18%
粗汽油干点/℃	199.3	201.5	1.10%
轻柴油95%馏出点/℃	358.7	363.4	1.31%

参数	模拟值	指标
干气C₃体积分数/%	0.94	<2%
液化气C₂体积分数/%	0.22	<0.5%
液化气C₅体积分数/%	0.02	<1.5%
稳定汽油雷德蒸气压/kPa	57.8	45~85