The Study of Process Design for Production of the Clean Fuel Dimethyl Ether (DME)

You-Syuan Chen, Jyun-Da Lin, Jhen-Ren Lee, An-Li Shieu, Jing-Jie Lan, and Gow-Bin Wang. Department of Chemical and Materials Engineering / Green Technology Research Center, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan, 33302, Taiwan

It is known that dimethyl ether (DME) has wide application, such as solvent, propellant, chemical intermediate, refrigerant replacement, LPG substitute and transportation fuel. Furthermore, DME has currently attracted considerable attention as an alternative clean fuel for diesel engines because it can emit much less pollutants such as CO, NOx and particulates. Traditionally, in industrial processes, DME is produced by dehydration of methanol using acidic porous catalyst. Methanol is commercially synthesized from CO/CO2 hydrogenation over Cu-based catalyst. Thus one can prepare DME from synthesis gas (syngas) in a two-step (or indirect) process of syngas to methanol and further to DME. Recently, it has been reported that DME can be synthesized from syngas in a single-step (or direct) process, which is more thermodynamically and economically favorable than the indirect process.

By studying the process development of the DME synthesis presented in the literature, this work first use commercial process simulators to analyze the traditional DME processes. The engineering economic analysis and optimal operating conditions of the processes are clearly evaluated. Plantwide control schemes are then developed to meet the desired production specifications. For the newly developed DME processes such as single-step process and two-step process, process simulators are used for designing preliminary process flow diagrams (PFDs). Results of the steady-state and dynamic simulations of these DME processes are then used to demonstrate those shown in the literature. Finally, the most feasible DME process flowsheet is presented to the academic and industrial societies for further studies.

Keywords: Clean Fuel, DME process, Process design, Process flowsheet, Plantwide control