Developing a mathematical model for the complete kinetic cycle of direct synthesis of DME from Syngas through the CFD technique

Abstract

Abstract It is well known that the direct synthesis of Di-Methyl Ether (DME) from the Syngas is highly exothermic; therefore, the temperature control for its production and hence a suitable heat transfer pattern is of ought most significance to the success of such process. As such, slurry bubble column reactor is recognized to be a more suitable means for this purpose than other choices including fixed bed reactor which is the usual type of system in which direct DME synthesis takes place. In other words, slurry reactors are desirable due to having suitable heat and mass transfer properties. In this research a mathematical model for direct synthesis of DME from synthesis gas in a slurry reactor for a complete kinetic cycle including; CO consumption, Water-Gas shift reaction and methanol dehydration steps has been developed and evaluated. This is done through FLUENT software incorporating k-ɛ model with 10% intensity (i.e.; usual industrial value) and reactor hydrodynamic diameter of 8 cm. Then, investigation of effects of various parameters such as pressure (in the range of 25 to 40 bars), temperature (between 220-280 °C), inlet feed flow rate (of 200 ml/min) and inlet feed composition (of CO:H2 = 1:1) on the performance of the reactor in terms of CO conversion and selectivity toward production of the DME in this process were undertaken. It is noteworthy, that the maximum error resulted from comparison of results obtained from current model and those of experimental data is less than 10% for conversion of CO selectivity toward DME which are reasonable considering assumptions utilized.