工业规模CO_2管道泄放过程中的压力响应及相态变化

Pressure response and phase transition in process of CO_2 pipeline release in industrial scale

基于CO2相态分别进行了气相、气液两相和超临界状态的3组工业规模CO2管道(长256 m,内径233 mm)泄放实验,分析了CO2管道泄放过程中的压力响应和相态转变过程。研究表明:在管道内,气相CO2泄放开始时压力发生突降,而后压降停滞或减慢;管内相态主要为气态,但管道末端温度大幅下降使该处形成气液均相CO2。泄放口位于气液界面之上的气液两相CO2泄放中,减压波多次反射并导致多次压力突降和反弹;管内相态由气液分层向气液均相转变,管道顶部和底部气液均相CO2先后向气相CO2转变。超临界CO2泄放中的压力突降和反弹发生在临界区域附近,且压力穿过临界压力时,压变速率会停滞或减慢;管内相态经历了超临界、气液均相和气相泄放3个过程。

Three groups of CO2 pipeline release experiments were performed using an industrial scale （256 m long, 233 mm id） instrumented pipeline with CO2 pre-discharge phase of gas phase, gas-liquid phase and supercritical phase, respectively. The pressure response and the phase transition were recorded and analyzed in the process of CO2 pipeline release. The results showed that when the pressure wave front arrived, the pressure fall and stagnation appeared in the process of gaseous CO2 release. The phase of CO2 in the pipeline during the gaseous CO2 release was mainly in gas state, but the temperature at the end pipe decreased sharply, leading to the formation of gas-liquid homogeneous CO2. The decompression multiple reflection led to multiple pressure fall sharply and rebound in the release of gas-liquid CO2. Gas-liquid layered CO2 transformed to gas-liquid homogeneous CO2 in the phase transition process of gas-liquid CO2, and then the gas-liquid homogeneous CO2 at the top of pipeline transformed to the gas CO2 and consequently the bottom. The pressure fall sharply and rebound appeared near critical region in the release of supercritical CO2. When the pressure passed through the critical pressure line, the pressure change rate could be stagnation and slow down. The discharge of the supercritical CO2, gas-liquid homogeneous CO2 and gas CO2 appeared in the process of supercritical CO2 release.