روند همگرايي محاسبات تعادلي هيدرات گازي متان در تعادل (جامد-بخار) و (جامد-مايع)

Convergence Procedure of Methane Gas Hydrate Equilibrium Calculation in HV and HLW Equilibrium

In some special conditions of hydrate forming, three hydrate-vapor-liquid phases are equilibrated together. In this research, thermodynamic hydrate equilibrium in binary mixture of methane and water with VPT equation of state and Danesh mixing rule and using Van der Waals Plauteeuw model for hydrate solid phase by attending to (HVL W) equilibrium phases is studied. In this purpose equilibrium pressure, once by using HV state and another time with HL W. and by two suggested algorithm is calculated. Comparison between calculation results and available experimental data in 262.4-285.9 K temperature range for methane hydrate pressure, shows that if two phases chosed from three equilibrium phases, HV equilibrium phases must be used and then equilibrium percent in other phases will obtain. Calculated average error percent in HV equilibrium state of two methods is 9.21%, although this percent in HL W state is 23.23%.