基于钠基吸附剂的烟气脱碳系统余热利用研究

Waste heat recovery from sodium-based CO2 capture process in coal-fired power plants

针对基于钠基固体吸附剂的燃烧后脱碳技术应用于燃煤电厂后综合能耗偏高的问题,本文提出与供热机组结合的碳捕集/供热双机组系统,利用低温热网回水回收系统低品位余热。依据双机组的抽汽混合与否构建了两种系统流程,分析了两种不同方案下的系统性能。研究结果表明,在有效回收脱碳系统碳酸化反应余热后,独立抽汽方案中碳捕集综合能耗从4.05GJ/tCO2降低至1.26GJ/tCO2,而混合抽汽方案中碳捕集综合能耗降低至1.13GJ/tCO2,同时双机组系统的热网供热量较单供热机组分别增加了67.5%和72.8%,经济效益显著。分析了混合抽汽方案的系统中碳捕集综合能耗随相关运行参数变化的规律,发现碳酸化反应温度和热网回水温度因为能够直接影响系统余热利用程度因而更易对碳捕集综合能耗产生影响。

Focused on the huge energy consumption by sodium-based CO2 capture process of the postcombustion CO2 capture technology,a cogeneration unit(CU)was integrated into the coal-fired power plant with the CO2 capture process(CCPP),in which the returned water from the heat network could be used to recover the lower-grade waste heat.Two different configurations of this CCPP-CU system,namely the separated extraction configuration and the mixed extraction configuration,were proposed,and the thermal performance of these two configurations was analyzed.Results showed that the comprehensive energy consumption of the separated extraction configuration and the mixed extraction configuration could be reduced from 4.05GJ/t CO2 to 1.26GJ/t CO2 and 1.13GJ/t CO2,respectively.Besides,the corresponding heat capacity of the CCPP-CU system was increased by 67.5%and 72.8%,which showed remarkable economic benefits.Effects of key parameters on the energy consumption of the mixed extraction configuration were investigated,which showed that the carbonation reaction temperature and the heat network return water temperature had great impact on the utilization ratio of the waste heat and the energy consumption of CO2 capture system.