LI Jiangfei, DUAN Xinghua, LI Yanfang, ZHANG Kang, ZOU Zhenchun, WU Changchun, CHEN Yingchao, LU Guoqiang
Pipeline transportation is regarded as an economical and effective way to transport CO2. The captured CO2 generally contains such impurities as N2, O2, CH4, Ar, and H2O. The type and content of impurities will impact the properties of CO2-rich mixture and subsequently the flow characteristics. The physical properties of pure CO2 were calculated and analyzed using Matlab based on Span Wagner EOS. Then the uniformly most accurate EOS for CO2-rich mixture was selected by comparing the calculation accuracy of the BWRS, SRK and PR EOS. Based on PR EOS, which has been proved to be the most proper EOS for CO2-rich mixture, a one-dimensional compressible flow model was developed to describe the steady and transient flow characteristics of CO2-rich mixture in the pipeline. Finally, the steady simulation under different flow states (supercritical state, dense phase, liquid state, gaseous state), impurities (type and content), and pipe parameters was conducted. The results show that PR EOS is the most proper EOS for CO2-rich mixture. Compared with gas transportation of CO2 pipeline, the pressure drop of dense phase and supercritical state transportation is relatively small, while the pressure drop of dense phase transportation is the least. Different types of impurities have different effects on broadening the gas-liquid two-phase region of CO2-rich mixture. Compared with that of natural gas pipeline, laws of steady flow of CO2-rich mixture pipeline are revealed, which may provide theoretical guidance for efficient operation and safe control of CO2 pipeline.
