CH4-H2O体系中的热力学计算及甲烷水合物相平衡

Thermodynamic calculations in the system CH4-H2O and methane hydrate phase equilibria.

作者信息

Circone Susan, Kirby Stephen H, Stern Laura A

机构信息

U.S. Geological Survey, 345 Middlefield Rd. MS 977, Menlo Park, California 94025, USA.

出版信息

J Phys Chem B. 2006 Apr 27;110(16):8232-9. doi: 10.1021/jp055422f.

DOI:10.1021/jp055422f

PMID:16623501

Abstract

Using the Gibbs function of reaction, equilibrium pressure, temperature conditions for the formation of methane clathrate hydrate have been calculated from the thermodynamic properties of phases in the system CH4-H2O. The thermodynamic model accurately reproduces the published phase-equilibria data to within +/-2 K of the observed equilibrium boundaries in the range 0.08-117 MPa and 190-307 K. The model also provides an estimate of the third-law entropy of methane hydrate at 273.15 K, 0.1 MPa of 56.2 J mol(-1) K(-1) for 1/nCH4.H2O, where n is the hydrate number. Agreement between the calculated and published phase-equilibria data is optimized when the hydrate composition is fixed and independent of the pressure and temperature for the conditions modeled.

摘要

利用反应的吉布斯函数，根据CH₄-H₂O系统中各相的热力学性质，计算了甲烷笼形水合物形成的平衡压力和温度条件。该热力学模型在0.08 - 117 MPa和190 - 307 K范围内，能将已发表的相平衡数据精确再现到观测平衡边界的±2 K以内。该模型还给出了在273.15 K、0.1 MPa下，1/nCH₄·H₂O（其中n为水合数）甲烷水合物的第三定律熵的估计值为56.2 J mol⁻¹ K⁻¹。当水合物组成固定且与所模拟条件下的压力和温度无关时，计算得到的相平衡数据与已发表数据之间的一致性达到最佳。