Dimethyl Ether Production from Gasification of Victorian Brown Coal - Process Model and Related Preliminary Experiments

Being reactive and spontaneously combustible, dried Victorian brown coals can not be exported, and have to be used in mine-mouth power stations which also suffer from low efficiency and high CO2 emission. Synthesis of dimethyl ether (DME) is an option for the production of liquid fuel, a transportable product for power generation and transportation. This paper presents a steady-state process model for DME production using brown coal. This model includes drying, an equilibrium model for coal gasification and a kinetic model for DME synthesis. Effect of various parameters on the performance of the process was evaluated. According to the simulation results, synergy of the reactive system for direct synthesis of DME is properly achieved when CO2 is removed from the fuel gas prior to feeding to the DME synthesis reactor. The yield of DME was found to be a maximum for H2 to CO molar ratio of 1.41 and 0.81 at the gasifier outlet and the DME reactor inlet, respectively. Process heat integration, and design of appropriate catalyst for gasification and DME synthesis can result in further improvements in the process. Initial gasification and catalytic water gas shift reaction experiments indicate favorable gas composition for the DME synthesis process.