关键词: 二氧化碳, 管道泄放, 压力响应, 相变, 气液两相流

Abstract:

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.

Key words: carbon dioxide, pipeline release, pressure response, phase change, gas-liquid flow