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In this article, experimental data on methane hydrate formation in mixtures of water and acetone are presented. For eight different acetone-water mixtures, the phase transition hydrate + liquid + vapor f liquid + vapor (HLV f LV) was determined in the pressure range 2.50 < p/MPa < 11.25. In addition, the experimental data obtained were described by a model that takes into account the variation of the enthalpy of hydrate formation as a function of pressure and acetone concentration. The average absolute temperature difference in the representation of the hydrate formation temperatures of methane in the presence of acetone is less than 0.32 K.

ammerschmidt (1 934) developed an empirical method for predicting the hydrate formation temperature for natural gas H constituents in the presence of alcohol. ('Alcohol' is used here to describe alcohols and polyhhydroxy alcohols, or glycols.) Subsequently, several other models have been suggested, for example, Anderson and Prausnitz (1 986) and Moshfeghian and Maddox (1 993).In the presence of electrolytes, the method of Englezos and Bishnoi (1 988) is applicable. Their procedure uses the activity model developed by Pitzer and Mayorga (1 973) to predict the water activity coefficient in the presence of electrolytes. Their model is not recommended for hydrate forming gases with high solubility in the water phase. Javanmardi and Moshfeghian (1996) and later Javanamardi et al. (1 998) took a different approach and incremented the pure water hydrate formation temperature to predict conditions of incipient hydrate formation in the presence of electrolytes. Englezos (1 992), by using flash calculation algorithms and the fugacity model of Aasberg-Peterson et al.(1 991), predicted the temperature for incipient hydrate formation in single aqueous electrolyte solutions. Javanmardi and Moshfeghian (2000) used the same activity model to predict the hydrate formation temperature in mixed aqueous electrolyte solutions. Yousif and Young (1994), based on modification of the Hammerschmidt model, developed a simple model to predict the hydrate temperature suppression of aqueous mixtures of salts and a single alcohol. Their correlation is restricted to the prediction of the hydrate condition for a specified gas mixture; however, we used it to predict hydrate formation conditions for other systems. In the Nasrifar et al.( 1 998) work, the hydrate formation temperature in the presence of mixed electrolytes and alcohols is calculated by adding a correction to the hydrate formation temperature in the presence of inhibitors. Therefore, their method is a two-step procedure.In the present work, a new method is suggested for direct prediction of hydrate temperature in the presence of both aqueous electrolyte solutions and a single alcohol. The model is based on the extension of the water activity model to the above systems. The suggested method is A new thermodynamic model for calculating the hydrate formation temperature of different hydrate formers in aqueous solutions of both electrolytes and a single alcohol has been presented. This method uses a generalization of the Aasberg-Petersen model for water activity. For calculation of water activity in the presence of electrolytes, the effect of alcohols was taken into account without using any new fitting parameters. The results are in good agreement with published experimental data.

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Experimental and thermodynamic results for methane hydrate dissociation conditions in the simultaneous presence of ethanol and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4) ionic liquid (IL) in aqueous solution are presented. Three different aqueous solutions including solution 1 (0.0142 mole fraction of ethanol, 0.0060 mole fraction of BMIM-BF4), solution 2 (0.0348 mole fraction of ethanol, 0.0059 mole fraction of BMIM-BF4) and solution 3 (0.0549 mole fraction of ethanol, 0.0058 mole fraction of BMIM-BF4) were used. An isochoric pressure-search method was used to perform the measurements. The experimental pressure and temperature ranges are (3.18 to 8.32) MPa and (273.6 to 283.3) K, respectively. The thermodynamic inhibition effects of these solutions on methane hydrate dissociation were observed and solution 3 leads to the strongest inhibition effect. The average hydrate dissociation temperature reduction for methane hydrate in the presence of solutions 1, 2, and 3 are approximately 1.0, 2.2, and 3.7 K, respectively, in comparison with the pure water case. Furthermore, to predict methane hydrate dissociation conditions, a van der Waals-Platteeuw (vdW-P) type model was used. The activity of water in the liquid/aqueous phase is computed using the NRTL activity coefficient model and the fugacity of the gas phase is accounted using the Peng–Robinson equation of state (PR EoS). Results indicate that there is a good agreement between the experimental and modeled data.

In this work, experimental hydrate dissociation conditions of methane in the presence of 0.06, 0.10, and 0.20 mass fractions of methanol and 0.10 and 0.25 mass fractions of ethane-1,2-diol in aqueous solutions are reported. In addition, phase equilibria of a ternary mixture of methane (0.9319 mole fraction) + ethane (0.0481 mole fraction) + propane (0.02 mole fraction) in the presence of 0.25 mass fraction of ethane-1,2-diol aqueous solution is investigated. A high-pressure equilibrium cell is used for measurement of hydrate dissociation conditions in the temperature range of (265.4 to 282.0) K and pressure range of (1.97 to 6.96) MPa. The experimental gas hydrate dissociation conditions are modeled using the van der Waals and Platteeuw (vdW-P) solid solution theory for dealing with the hydrate phase and the Valderrama–Patel–Teja equation of state (VPT-EoS) along with the nondensity dependent (NDD) mixing rules to account for the fluid phases. The obtained experimental data are finally compared with selected experimental data from the literature as well as the model predictions, and acceptable agreements are observed.