Determination of P–V–T–x properties of the CO2–H2O system up to 573.15K and 120MPa—Experiments and model
Determination of P–V–T–x properties of the CO2–H2O system up to 573.15K and 120MPa—Experiments and model
复制标题
测定高达 573.15K 和 120MPa 的 CO2-H2O 体系的 P-V-T-x 特性——实验和模型
DOI：
10.1016/j.chemgeo.2016.01.011
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Lantao Geng
中科院分区：
文献类型：
--
作者：
Qingcheng Hu;Huirong Guo;Xinbiao Lü Wanjun Lu;Ying Chen;Yan Zhu;Lantao Geng
作为本研究的一部分，正在开发一种新的方法来测量CO2-H2O系统在273.15至513.15 K和30至120 MPa压力下的压力-体积-温度-组成（P-V-T-x）特性。CO2-H2O溶液的密度是通过测量密封在毛细管高压光学池（HPOC）中的溶液的体积变化，通过系统校正来确定的。这项研究部分填补了稀CO2-H2O系统的电流密度/摩尔体积数据缺口。结果表明，CO2-H2O混合物的密度在298.15 K以下变化不大，然后在常压下随温度升高比ρ H2O下降得更快，最后在高温区（如30 MPa下489 K以上）低于ρ H2O。该枢转温度（Tp，在此温度以上ρCO2-H2O变得低于ρH2O）随着压力的增加而单调增加（当压力达到120 MPa时达到575 K）。计算得到的CO2在水中的表观摩尔体积（VΦ，CO2）与CO2浓度无关，但在温度高于298.15 K时与压力呈负相关。在此基础上提出了一个适用于稀CO2-H2O体系的修正V Φ，CO2模型。这个修正后的模型可以再现当前和以前的密度数据与可接受的误差范围内的温度高达573.15 K和压力高达120 MPa。它可以可靠地用于模拟CO2到含水层中的地质封存，并用于研究地质流体的P-V-T-x演化（例如，含CO2的含水成矿流体）。
A new method is being developed as part of this study to measure the Pressure–Volume–Temperature–composition (P–V–T–x) properties of the CO2–H2O system at temperatures from 273.15 to 513.15 K and pressures from 30 to 120 MPa. The density of a CO2–H2O solution is determined by measuring the volumetric change of the solution sealed in a capillary High-Pressure Optical Cell (HPOC), through a systematic correction. This study partially fills the current density/molar volume data gap for dilute CO2–H2O systems. Data show that the density of CO2–H2O mixture (ρCO2–H2O) changes little below 298.15 K, then decreases more rapidly thanρH2Owith increasing temperature at constant pressure, and eventually becomes lower thanρH2Oin high temperature range (for example, above 489 K at 30 MPa). This pivoting temperature (Tp, above whichρCO2–H2Obecomes lower thanρH2O) monotonously increases with increasing pressure (to 575 K as the pressure reaches 120 MPa). The calculated apparent molar volume of CO2in water (VΦ,CO2) is independent of CO2concentration, but is negatively correlated to pressure when the temperature is above 298.15 K. A revisedVΦ,CO2model for dilute CO2–H2O systems is proposed based on this study. This revised model can reproduce both the current and previous density data with an acceptable error range at temperatures up to 573.15 K and pressures up to 120 MPa. It can be used reliably to simulate geological sequestration of CO2into water aquifers, and in the study ofP–V–T–xevolution of geo-fluids (e.g., CO2-bearing aqueous ore forming fluids).