关键词: 烟道气, 二氧化碳捕集, 夹点技术, 优化, 回收, 投资成本

Abstract: Energy saving technologies for CO2 capture systems are receiving extensive attentions from both academic researchers and industries. However，most of these researches focused on the CO2 capture systems，instead of the waste heat utilization of the flue gas and practical recovery schemes. However，in order to improve the energy efficiency of the CO2 capture systems，it was very important to recover the thermal energy from the flue gas. This paper took the flue gas processing system coupled with a 660MW coal-fired power plant as an example，the temperature of pinch point was determined by use of “problem table” method. The initial heat exchanger network （HEN）was optimized by matching hot flows and cold flows. And three new retrofit schemes were obtained：The one-stage HEN for energy recovery of the flue gas was to use the flue gas to heat the makeup mono ethanol amine (MEA) solvent；the two-stage HEN could be further divided into two networks - the first one recovered the heat of the flue gas directly by letting the flue gas heat the rich solvent and the makeup MEA solvent sequentially，the second one recovered the heat of flue gas indirectly，letting the flue gas heat water first and then the heated water was sent to heat both the rich and the makeup MEA solvent. The three new HENs were compared in terms of investment cost，and it was found that the most cost effective method was one-stage HEN.

Key words: flue gas, CO2 capture, pinch technology, optimization, recovery, investment cost