Vapor-Liquid Equilibrium of a Ternary System containing Dimethyl ether (DME) and Light Hydrocarbons

Recently, dimethyl ether (DME) has been paid much attention as a clean fuel. DME has many advantages as a substitute for liquefied petroleum gas (LPG). Sulfur oxides (SOx), and particulate matters (PM) are not produced at the combustion. Infrastructures and equipments for LPG can be used with slight improvements, because physical properties of DME are similar to those of light hydrocarbons, propane and butane. Now, the industrial production of DME is about 10,000 ton/year in Japan, and the DME has been mainly used as an aerosol propellant. In this last decade, DME can be directly synthesized from water gas, carbon monoxide and hydrogen, by use of a new type catalyst dispersed in fluids, and a pilot plant has already produced DME with a rate of 100 ton/day. So, a huge amount of DME will be supplied in the future of Japan. Though the experimental data of vapor-liquid equilibrium (VLE) are essential for the practical usage of fuel mixture, there are few data containing DME and light hydrocarbons. In this study, a recirculate type apparatus was designed to measure VLE, and the experimental VLE data were obtained for the three binary, propane + DME, DME + butane, propane + butane, and a ternary, propane + DME + butane, systems at 313.15 K. The binary data were correlated with Benedict-Webb-Rubin (BWR) equation of state and a conventional mixing rule. Using the optimized binary interaction parameters, VLE was estimated for the ternary system.