二氧化碳长输管道投产置换过程模拟分析

CO_2管道是碳捕集、利用及封存(carbon capture, utilization and storage, CCUS)技术中连接CO_2排放地和封存地或注入地的关键环节,CO_2管道投产置换主要是利用N_2惰性且高吸水性的特点完成管道清洗干燥并为随后管道调试做好准备。目前关于CO_2管道投产置换的研究较为缺乏,通过SPS软件研究了延长石油某CO_2管道在不同输送介质组成、封存压力条件下的投产置换过程,并与天然气管道的投产置换过程进行对比,比较分析了CO_2与天然气投产置换过程所需N_2量、时间和升压所需气量的不同。结果表明:在压力升至CO_2临界点附近时,CO_2密度会发生突变大幅上升,且升高单位压力所需气量减少,并在升压结束时CO_2消耗量小于天然气消耗量。管内介质组成变化对N_2置换的影响不大,CO_2在管道内更易发生相变,不宜在置换完成之后直接升压投产。

Analysis and Simulation on the Commissioning replacement process of Carbon Dioxide Long-Distance Pipeline

CO2 pipeline is the key link between CO2 emission site and storage or injection site in CCUS technology. The main purpose of CO2 pipeline commissioning replacement is to clean and dry the pipeline and prepare for the subsequent commissioning of the pipeline by using the characteristics of inert and highly absorbent N2. In this paper, the process of CO2 pipeline commissioning replacement is studied by SPS software under different conditions of transport fluid mixture composition and storage pressure. The results show that the CO2 density increases abruptly when the pressure rises near the CO2 critical point, and the gas volume required per unit of pressure increasing reduces, and the CO2 consumption is smaller than the natural gas consumption at the end of the ramp-up. The change of fluid mixture composition in the pipe has little effect on nitrogen replacement, and CO2 is more likely to undergo phase change in the pipeline, so it is not suitable to put into operation directly after the replacement is completed.