CO2置换甲烷水合物热力学影响因素实验研究

Experimental study of thermodynamic effects on replacement of methane hydrates by CO2

关键词:  CO2  甲烷水合物  置换率  热力学

Key words:  CO2  methane hydrates  replacement rate  thermodynamics

摘要:

CO2置换法作为一种集温室气体储存和天然气水合物开发于一体的方法引起了国内外学者的注意。通过检测置换过程中气相组分的变化情况,研究了压力和温度对CO2置换甲烷水合物置换率的影响。实验体系为纯水,置换反应时间为50h。实验结果表明,在CO2注入压力为2.5MPa时,当温度分别为273.15K、274.15K、275.65K、276.15K时,置换反应结束时气相中CH4的摩尔分数从置换反应开始时的1.56%分别达到39.74%、41.89%、45.45%、48.04%。在置换温度为275.65K时,当CO2注入压力分别为2.2MPa、2.5MPa、2.8MPa、3.1MPa时,置换率分别达到44.87%、45.45%、46.66%、47.21%。可见,置换温度与压力在一定范围内对置换率的影响是正向的,但影响程度不大。

Abstract:

Replacing methane with CO2 in the hydrate structure,storing CO2 and producing methane from methane hydrate reservoirs have attracted much attention of the researchers worldwide.The effects of pressure and temperature on replacement rate were investigated by measuring the change of the methane molar percentage in the gas phase.The test system was in pure water,and the replacement reaction lasted 50 hours.The experimental results show that the methane molar percentage in the gas phase at the end of replacement process is increased from the initial 1.56% to 39.74%,41.89%,45.45% and 48.04% respectively corresponding to the replacement temperature at 273.15 K,274.15 K,275.65 K and 276.15 K with the CO2 charge pressure at 2.5 MPa.On the other hand,the replacement rate respectively reach 44.87%,45.45%,46.66% and 47.21% corresponding to the CO2 charge pressure from 2.2 MPa to 2.5 MPa,2.8 MPa,3.1 MPa with the replacement temperature at 275.65 K.Therefore,it is concluded that the influence of temperature and pressure on replacement rate is positively in some ranges,but not great.