Simulation and sensitivity analysis of flue gas environmental protection island system in coal-fired unit based on ASPEN Plus

doi:10.16085/j.issn.1000-6613.2021-1502

Abstract

Abstract:

The removal process of flue gas pollutants in the environmental protection island system of a 600MW coal-fired power unit was modeled with ASPEN Plus. Simulations were carried out to perform sensitivity analysis of ammonia-nitrogen molar ratio, pH of the circulating slurry, desulfurization tower liquid-gas ratio, flue gas temperature and flue gas flow from the perspective of system engineering. Further the static response characteristics of the environmental protection island system to these parameters were obtained. Results showed that the molar ratio of NH₃ to nitrogen should be slightly higher than 0.92 to reduce operating costs and NH₃ escape in SCR reaction based on vanadium-titanium catalyst. When the amount of escaped NH₃ was within the allowable range, increasing the pH of the circulating slurry is beneficial to enhance desulfurization and increase gypsum production. At the same time, the liquid-gas ratio should be as low as possible to reduce operating costs and nevertheless was not lower than 8. Otherwise, the desulfurization efficiency will be greatly decreased. The flue gas temperature at the outlet of the economizer should be less than 350℃, and within the range of 310—350℃, the system showed a comprehensive better desulfurization and denitrification efficiency. The environmental protection island system had strong adaptability to flue gas flow changes. The simulation results provided a quantitative reference for the optimal operation and intelligent control of the environmental protection island system.

Key words: environmental protection island, flue gas, process systems, simulation, sensitivity analysis, molar ratio of NH₃ to nitrogen, pH of circulating slurry, liquid-gas ratio

摘要：

以某600MW燃煤机组环保岛系统为研究对象，利用ASPEN Plus软件对烟气污染物脱除过程进行建模，并通过仿真实验对氨氮摩尔比、循环浆液pH、脱硫塔液气比、烟气温度、烟气流量等运行参数进行了敏感性分析，获得了烟气污染物脱除系统对各参数的静态响应特性。结果表明，对于在钒钛基催化剂上发生的选择性催化还原脱硝反应，氨氮摩尔比应略高于0.92，以保证脱硝效率，减小运行成本和氨逃逸量；当氨逃逸量在允许范围内时，提高浆液pH有利于增强脱硫作用和增加石膏产量，同时，应尽量降低脱硫塔液气比以减小运行成本，但液气比不可小于8，否则系统脱硫效率将大幅下降；省煤器出口烟温应小于350℃，控制在310～350℃时，系统综合脱硫脱硝效果较好；对于烟气流量变化，环保岛系统具备较强的适应能力。这些结果为环保岛系统的优化运行和智能控制提供了定量参考。

关键词: 环保岛, 烟道气, 过程系统, 模拟, 敏感性分析, 氨氮摩尔比, 浆液pH, 液气比

CLC Number:

X773

LIU Zuoren, XU Chuanlong, TANG Guanghua. Simulation and sensitivity analysis of flue gas environmental protection island system in coal-fired unit based on ASPEN Plus[J]. Chemical Industry and Engineering Progress, 2021, 40(12): 6564-6573.

刘祚人, 许传龙, 汤光华. 基于ASPEN Plus的燃煤机组环保岛系统仿真与敏感性分析[J]. 化工进展, 2021, 40(12): 6564-6573.

Figures/Tables 18

References 23

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粒径/μm	质量分数/%
合计	100
0.7~1.0	2
1.0~2.5	4.3
2.5~6.0	28.3
6.0~10.0	29.1
10.0~100	36.3

粒径/μm	质量分数/%
合计	100
0.7~1.0	2
1.0~2.5	4.3
2.5~6.0	28.3
6.0~10.0	29.1
10.0~100	36.3

污染物	入口浓度 /mg·m^-3		出口浓度 /mg·m^-3		脱除率 /%		脱除率相对误差绝对值/%
污染物	模型	实际	模型	实际	模型	实际	脱除率相对误差绝对值/%
NO	251.9	246.8	22.0	27.2	91.26	88.98	2.56
SO₂	1605	1578	11.2	10.5	99.34	99.33	0.01
烟尘	21553	22561	2.69	2.94	99.986	99.987	0.001

污染物	入口浓度 /mg·m^-3		出口浓度 /mg·m^-3		脱除率 /%		脱除率相对误差绝对值/%
污染物	模型	实际	模型	实际	模型	实际	脱除率相对误差绝对值/%
NO	251.9	246.8	22.0	27.2	91.26	88.98	2.56
SO₂	1605	1578	11.2	10.5	99.34	99.33	0.01
烟尘	21553	22561	2.69	2.94	99.986	99.987	0.001

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