温度对超临界CO_2置换CH_4的影响

为研究超临界CO_2置换CH_4过程中温度对置换效果的影响,以屯留煤样为研究对象,借助ISO-300型等温吸附仪对煤样进行了不同温度(35、45、55℃)、相同注入压力(12.7 MPa)条件下的CO_2置换解吸CH_4试验。研究结果表明:置换解吸过程中,超临界CO_2吸附相体积分数随着温度升高而增加,随压力降低而增大,CH_4吸附相体积分数呈相反变化趋势;超临界状态下,试验直接测得的气体吸附量为Gibbs吸附量,气体真实吸附量与压力之间符合Langmuir吸附曲线,且与Gibbs吸附量的差值随压力的升高而增大;试验压降范围内,温度为35℃条件时,CH_4气体单位压降解吸率最高,显示出温度接近临界温度时,超临界CO_2置换效果最佳。

Influence of temperature on the replacement of CH4 by supercritical CO2

An experiment for replacement of CH₄ by CO₂ was conducted under different temperatures (35, 45, and 55℃) and the same injection pressure (12.7 MPa) using ISO-300 isothermal adsorption experiment instrument for studying the influence of temperature on the replacement of CH₄ by supercritical CO₂. Coal samples of Tunliu mine were used as the research subjects. The results show that during the replacement and desorption process, the adsorbed phase concentration of supercritical CO₂ increased with increase of the temperature and decrease of the pressure, while the concentration variation of CH₄ was in an opposite way. Under supercritical conditions, laboratory measurement of the adsorption capacity is the adsorption of Gibbs. The relationship between real adsorption capacity and pressure accords with the Langmuir adsorption curve. With increasing pressure, the difference between calculated and Gibbs adsorption capacity increased. The CH₄ desorption rate at unit pressure drop reached the highest at the temperature of 35℃ under the experiment pressure drop, and when the temperature was close to the supercritical temperature, the replacement effect of supercritical CO₂ reached the best.