Process modelling of dimethyl ether production from Victorian brown coal—Integrating coal drying, gasification and synthesis processes

Power plants using Victorian brown coal operate at low efficiency. Being reactive and spontaneously combustible, dried brown coals cannot be exported either. Synthesis of dimethyl ether (DME) is one option for the production of liquid fuel, an exportable product for power generation and transportation. This paper presents a steady-state process model for DME production using brown coal including drying, gasification and DME synthesis. The yield of the DME was a maximum for H2 to CO molar ratio of 1.41 and 0.81 at the gasifier outlet and the DME reactor inlet respectively. A process efficiency of 32% and CO2 emission of 2.91 kg/kg of DME was obtained. Improved yield of DME is achieved when CO2 is removed from the fuel gas prior to feeding to the synthesis reactor. Integration of waste heat and design of appropriate catalyst for gasification and DME synthesis can result in further improvements in the process.

► Process model for DME synthesis from Victorian brown coal.
► Model includes drying of as-mined coal, gasification and DME synthesis.
► Steam drying of coal is beneficial than nitrogen drying.
► DME production from brown coal is more efficient than conventional power generation.
► First such work using brown coal.