基于LNG冷能的膜-深冷分离碳捕集耦合系统工艺模拟与分析

Process simulation and analysis of membrane-cryogenic separation carbon capture coupling system based on LNG cool energy

开发经济、高效和节能的碳捕集工艺,是碳捕集、利用与封存技术的重点研究方向之一。针对低浓度(体积分数小于12%)CO_(2)烟气,提出了一种基于液化天然气(LNG)冷能的膜-深冷分离碳捕集耦合系统工艺,弥补了采用单一碳捕集技术的缺陷,并利用了LNG蕴含的冷能,有望实现更低能耗的CO_(2)捕集。利用Aspen Plus软件对该工艺进行了模拟,对影响系统性能的关键参数(液化温度、压缩压力和渗透气CO_(2)浓度等)进行了灵敏度分析,并开展了相关实验研究。结果表明,模拟结果与实验结果具有较好的一致性,利用该工艺可以得到符合工程或商业应用要求的液态CO_(2)产品;工艺CO_(2)捕集率与产品纯度随液化温度和压缩压力呈趋势相反的变化,即随着液化温度的降低或者压缩压力的提高,CO_(2)捕集率增加,但产品纯度降低;在达到工艺指标要求(CO_(2)捕集率大于等于85%、产品纯度大于等于90%)的前提下,工艺最低CO_(2)捕集能耗为2.183 MJ/kg(即捕集1 kg CO_(2)的能耗为2.183 MJ)。本研究为从低浓度CO_(2)烟气中分离回收CO_(2)提供了新思路。

Developing an economical,efficient and energy-saving carbon capture process is one of the key research directions in carbon capture,utilization,and storage technology.A coupling system process for carbon capture based on liquefied natural gas(LNG)cold energy was proposed to address low-concentration(volume fraction less than 12%)CO_(2) flue gas.The process combines membrane separation and cryogenic separation,compensating for the shortcomings of using a single carbon capture technology.It also utilizes the cold energy inherent in LNG,which holds the potential for achieving lower energy consumption in CO_(2) capture.The process was simulated by Aspen Plus software,and sensitivity analysis was conducted on key parameters affecting system performance,such as liquefaction temperature,compression pressure,and permeate gas CO_(2) concentration.Experimental research was also carried out to validate the simulation results.The results indicate good consistency between simulation and experimental data,showing that the proposed process can provide liquid CO_(2) products that meet engineering or commercial application requirements.The carbon capture rate and product purity exhibit an inversely related trend with liquefaction temperature and compression pressure.In other words,as the liquefaction temperature decreases or the compression pressure increases,the carbon capture rate increases while product purity decreases.Under the premise of meeting the process’s target requirements(carbon capture rate greater than or equal to 85%,product purity greater than or equal to 90%),the lowest energy consumption for carbon capture in the process is 2.183 MJ/kg(the energy required to capture 1 kg of CO_(2) is 2.183 MJ).This study provides a novel approach to separate and recover CO_(2) from low-concentration CO_(2) flue gas.