烟气CO2捕集热能梯级利用节能工艺耦合优化

醇胺法捕集CO₂技术是一种较成熟的CO₂捕集技术，具有吸收速度快、脱除效果好等显著优点，但其操作费用高、解吸能耗大。本文以降低醇胺法捕集烟气中CO₂系统再生能耗为出发点，对常规醇胺法捕集CO₂工艺统进行了节能优化研究。在常规工艺流程基础上引入压缩式热泵节能技术，并利用Aspen Plus软件建立了基于压缩式热泵技术的CO₂捕集工艺流程模型。研究了压缩式热泵与机械蒸汽压缩回收（MVR）热泵、分流解吸、分布式换热、级间冷却4种节能工艺耦合，通过模拟计算与优化，结果说明了最佳节能工艺组合为“解吸塔压缩式热泵+贫液MVR热泵+分流解吸+级间冷却”耦合的CO₂捕集工艺流程，当解吸塔顶气体分流比为0.25∶0.75、冷富液分流比为0.05∶0.95、级间冷却器位于吸收塔17块塔板位置、吸收塔输入冷量为-3.0GJ/h时，系统再生能耗最低，为2.533 GJ/tCO₂，相比常规有机胺工艺（再生能耗4.204GJ/tCO₂）节能率39.748%。

Coupling optimization of energy-saving technology for cascade utilization of flue gas CO2 capture system

The alcohol-amine method is a mature CO₂ capture technology, which has the advantages of high absorption speed and good removal effect, but its operation cost is high and desorption energy consumption is large. Therefore, based on reducing regeneration energy consumption of CO₂ capture system in flue gas by amine method, the energy saving of conventional CO₂ capture system by amine method was studied in this paper. Based on the energy-saving research of conventional amine CO₂ process, the energy-saving technology of compressed heat pump was introduced, and the CO₂ capture process model based on compressed heat pump technology was established by Aspen Plus software. The coupling of compressed heat pump with MVR heat pump, split-flow desorption, distributed heat transfer and inter-stage cooling was studied. By simulation and optimization, the optimal energy-saving process combination was finally obtained as CO₂ capture process of “desorption tower compressed heat pump+lean-liquid MVR heat pump+split-flow desorption + inter-stage cooling” coupling. When the split-flow ratio of top gas of desorption tower was 1/3, the split-flow ratio of rich and cold liquid was 0.05. The inter-stage cooler was located on 17 trays of the absorption tower. When the input cooling capacity of the absorption tower was -3.0GJ/h, the regeneration energy consumption of the system was the lowest, which is 2.533GJ/t CO₂. Compared with the conventional organic amine process, the energy saving rate was 39.748%.