基于自热再生的化学吸收法CO2捕集工艺模拟及节能分析

Process simulation and energy saving analysis of CO2 capture by chemical absorption method based on self-heat recuperation

基于能量集成,将化学吸收CO2捕集工艺与烟道气余热回收单元耦合,应用自热再生理论对其优化,挖掘捕集过程高耗能单元的节能潜力,并使用计算机模拟软件Aspen Plus对该过程建模分析。优化后的捕集工艺实现了捕集过程反应热的回收,将塔顶蒸气的冷凝潜热回收作为塔底再沸器的热源,合理利用了烟道气余热和换热后的贫液能量,降低了系统对额外热源的需求。模拟结果表明,优化后的捕集工艺最小能耗为1.46 GJ/(t CO2),节能约41.36%。综合投资成本和运行费用对工艺进行经济性评价,优化后的捕集成本为326.70 CNY/(t CO2),较传统化学吸收法降低了12%。

Based on energy integration, the process of chemical absorption of CO2 is coupled with the flue gas waste heat recovery unit, and is optimized by self-heat recuperation to minimize the exergy loss of the high energyconsuming unit in the capture process, and the process was modeled by using computer simulation software Aspen Plus. The optimized process uses the heat recovery of the reaction heat released from the capture process for the endothermic reaction in the desorption process, realizing the recovery of reaction heat in the capture process.Meanwhile, by compressing the waste steam to recuperate the heat, which is exchanged with the liquid vaporization heat;flue gas waste heat and lean amine energy are rationally utilized. Moreover, the recuperated heat results in the reduction of the energy consumption for the desorption process so that the additional heat requirements are reduced in the capture system. The simulation results show that the optimized energy consumption of the capture process is1.46 GJ/(t CO2) and the energy saving is about 41.36%. The economic evaluation of the process is performed by the investment cost with the operating cost. As a result, the total cost of the optimized capture process is 326.70 CNY/(t CO2), which is 12% less than the traditional chemical absorption method. It indicates that the self-heat recuperation has great energy saving potential and could solve the sharp contradiction between the energy supply and the demand for a practical process.