燃煤机组变负荷运行下的脱硫废水零排放流程模拟分析

doi:10.11949/0438-1157.20241509

摘要/Abstract

摘要：

通过建立300 MW燃煤机组厂级全流程模型，对比分析了40%~100%额定工况（THA）下3种不同热源驱动的脱硫废水零排放技术的性能，揭示了电厂脱硫废水在热法浓缩过程中的水-能耦合平衡关系。结果表明，当机组负荷降低，负荷偏离额定值越多，热、电负荷差距越大，在40%THA下的热负荷率为45.76%。在3种脱硫废水零排放技术中，两种三效蒸发干燥方式的单位耗热量最低，为0.017 kJ/t，不到高温烟气旁路干燥方式的1/2，节能效果良好，其中三效烟气取热干燥方式利用的是烟气废热，不损失发电量，其锅炉效率和发电效率最高，在100%THA下分别为85.59%和32.25%，在降低能源成本和减少环境污染方面具有更大优势。相关研究可以为合理选择全工况脱硫废水处理技术提供依据。

关键词: 燃煤电厂, 变负荷, 脱硫废水, 零排放, 三效蒸发

Abstract:

By developing a plant-scale model of a 300 MW subcritical unit, the performance of three zero discharge technologies of desulfurization wastewater with different heat sources was compared under 40%—100% rated condition (THA) conditions. The model can present the water-energy balance in the thermal concentrating process. The results show that the more the unit load is reduced, the more the load deviates from the rated value, and the greater the gap between thermal and electrical load rate. The thermal load rate is 45.76% under 40%THA. Among the three desulfurization wastewater zero-emission technologies, the two three-effect evaporation drying methods have the lowest unit heat consumption of 0.017 kJ/t, which is less than 1/2 of the high-temperature flue gas bypass drying method, and have good energy-saving effects. Among them, the three-effect flue gas heat drying method uses flue gas waste heat without losing power generation. Its boiler efficiency and power generation efficiency are the highest, which are 85.59% and 32.25% respectively at 100%THA, and have greater advantages in reducing energy costs and reducing environmental pollution. The findings are expected to provide a basis for the reasonable selection of desulfurization wastewater treatment technology under all operation conditions.

Key words: coal-fired power plants, variable load, desulfurization wastewater, zero discharge, triple-effect evaporation

中图分类号:

TK 223

杨文毅, 由长福, 王海名. 燃煤机组变负荷运行下的脱硫废水零排放流程模拟分析[J]. 化工学报, 2025, 76(7): 3468-3476.

Wenyi YANG, Changfu YOU, Haiming WANG. Simulation and analysis of zero discharge of desulphurization wastewater under variable load processes from coal-fired units[J]. CIESC Journal, 2025, 76(7): 3468-3476.

图/表 15

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参数	数值
连续蒸发量/（t/h）	1021
过热蒸汽压力/MPa	16.7
再热蒸汽压力/MPa	3.2
过热蒸汽温度/℃	538
再热蒸汽温度/℃	538
省煤器出口烟温/℃	370
空气预热器出口烟温/℃	208

参数	数值
连续蒸发量/（t/h）	1021
过热蒸汽压力/MPa	16.7
再热蒸汽压力/MPa	3.2
过热蒸汽温度/℃	538
再热蒸汽温度/℃	538
省煤器出口烟温/℃	370
空气预热器出口烟温/℃	208

电负荷率/%	电负荷/MM	煤/(kg/h)	煤耗/(g/(kW·h))	比煤耗	热负荷率/%
100	298.51	113700	380.89	1.00	100
80	238.81	92640	387.93	1.02	81.48
60	179.11	72104	402.58	1.06	63.42
40	119.40	52026	435.72	1.14	45.76

电负荷率/%	电负荷/MM	煤/(kg/h)	煤耗/(g/(kW·h))	比煤耗	热负荷率/%
100	298.51	113700	380.89	1.00	100
80	238.81	92640	387.93	1.02	81.48
60	179.11	72104	402.58	1.06	63.42
40	119.40	52026	435.72	1.14	45.76

实际值		模拟值		相对误差/%
电负荷/MW	电负荷率/%	电负荷/MW	电负荷率/%	相对误差/%
298.51	100	298.51	100.00	—
238.81	80	238.14	79.78	0.27
179.10	60	177.49	59.46	0.90
119.40	40	115.36	38.65	3.38