CO2超临界态输送技术研究

为了提高CO₂管道输送效率，一般采用超临界密相输送。为此，利用组分热力学模型以及水力学模型，分别对CO₂液化管道输送、超临界输送和密相输送进行分析研究，对不同相态条件下的管道输送规律进行了模拟计算，得到了压力、温度等在输送过程的变化规律，并就压降-长度关系、压降-二氧化碳摩尔流量关系和压降-内径关系对3种输送方式进行了对比，得到如下结论：在相同的情况下，超临界输送时的压降比液化输送和密相输送的压降值要大，而液化输送的压降比密相输送大；超临界输送和密相输送的压力都很高，输送过程中基本不会发生气化，而液化输送随着输送过程中压力的降低、温度的升高，CO₂很容易气化；不同的输送方式无论从经济性还是能耗上都有很大的差别，输送状态的选择要根据整个系统的具体情况进行综合分析和评价。

Research on CO2 supercritical transportation technology

In order to improve pipeline transporting efficiency, CO_2 is generally transported in supercritical dense phase. By use of the component thermodynamic model and the hydromechanic model, this paper made in-depth investigation into three types of CO_2 transmission methods, namely CO_2 liquefaction pipeline transportation, supercritical transportation, and dense-phase transportation. It simulates and calculates the pipeline transportation regularity under different phase conditions and obtains the changing laws of pressure and temperature during the transportation process. It also conducts comparison studies on the relationships between the pressure drop and the length of pipeline, CO_2 molar flow, and the internal diameter of pipeline, respectively, of these three types of transmission methods. The results show that the pressure drop value of supercritical transmission is higher than that of the other two methods; and that of liquefaction pipeline transportation is higher than that of dense-phase transmission. The pressure of supercritical transmission and dense-phase transmission is high and gasification is basically impossible. However, in liquefaction pipeline transportation, as the pressure decreases, its temperature rises, and CO_2 can be easily gasified. The transportation methods differ greatly from each other economically and in terms of energy consumption. The transportation state should be selected in accordance with the integrative analysis and evaluations of the condition of the entire system. This provides good references to the design of CO_2 transportation pipelines.