二氧化碳长输管道投产置换过程模拟分析

Analysis and Simulation on the Commissioning Replacement Process of Carbon Dioxide Long-distance Pipeline

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。

CO_(2) pipeline is the key link between CO_(2) emission site and storage or injection site in carbon capture,utilization and storage(CCUS)technology.The main purpose of CO_(2) 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 N_(2).At present,there is a lack of research on the production and replacement of CO_(2) pipeline.The production and replacement process of a CO_(2) pipeline in Yanchang oil company under different transmission medium composition and storage pressure was studied by using SPS software,and compared with the production and replacement process of natural gas pipeline.The differences of nitrogen amount,time and pressure rise required in the production and replacement process of CO_(2) and natural gas were analyzed.The results show that the CO_(2) density increases abruptly when the pressure rises near the CO_(2) critical point,and the gas volume required per unit of pressure increasing reduces,and the CO_(2) 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 CO_(2) 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.