CO₂ pipeline transportation characteristics with different pipe diameters under different pressures & temperatures

In order to study CO₂ pipeline transportation technology further, the CO₂ transportation project of 100×10⁴ t/a was taken as an example, the simulation software Pipephase was adopted for modeling to simulate the transportation process of CO₂ in gas phase, liquid phase and supercritical phase under the conditions of different pipe diameters, temperatures and pressures. It is indicated that in three pipeline transportation modes (i.e., gas phase, liquid phase and supercritical phase), the pressure drop is seldom affected by the pipe diameter, but only affected by the transportation distance. The density and viscosity of pipeline CO₂ are not affected by transportation distance, temperature or pressure in the transportation mode of gas phase while it is mainly affected by the temperature in the transportation modes of liquid phase and supercritical phase. It is necessary to avoid high pressure and pseudocritical regions during the transportation of gas phase, to operate under higher pressure during the transportation of liquid phase, and to prevent temperature and pressure from reaching critical points during the transportation of supercritical phase. It is shown from comprehensive comparison and analysis that as for CO₂ transportation projects with the capacity of million tons, the transportation mode of supercritical phase is preferred for moderate- and long-distance CO₂ transportation pipelines in sparsely populated regions, and the transportation mode of gas phase is preferred for moderate- and short-distance CO₂ transportation pipelines in highly populated areas.