Modeling and Simulation of an Integrated Micro Packed Bed Reactor-Heat Exchanger Configuration for Direct Dimethyl Ether Synthesis

Abstract

The application of an integrated micro packed bed reactor-heat exchanger for highly exothermic syngas conversion to dimethyl ether was investigated by numerical simulation. A three-dimensional pseudo-homogeneous model was developed to describe concentration and temperature distributions inside a single reaction slit. The model was adopted at low Reynolds numbers (small catalyst particles and long residence times). The simulation results reveal that the micro packed reaction slit is close to isothermal, and a negligible temperature gradient is predicted also for a doubling of the critical reaction slit dimension, i.e. the reaction slit height. The flow in the reaction slit was modelled by Brinkman's equation and it was found that the pressure drop in wide range of gas velocity was not significant. The reactor simulation showed good agreement with experimental results and could be further developed to assess the potential of microstructured packed bed reactors to intensify large-scale industrial processes.

Direct dimethyl ether synthesis from synthesis gas: The influence of methanol dehydration on methanol synthesis reaction

“…The reactor consists of a 6 cm long reaction slit with rectangular cross section of 8.8 × 1.5 mm 2 , sandwiched between cross flow channels for circulation of a heat transfer oil. Such reactors have been studied earlier under similar operating conditions for the methanol [21][22][23] and the direct DME [24][25][26] syntheses, and established as practically isothermal, isobaric, free from mass transfer limitations, and with a narrow residence time distribution. Premixed synthesis gas with H 2 to CO molar ratio of either 1 (Syngas-1) or 2 (Syngas-2) was used as feed.…”

Catalyst Deactivation During One-Step Dimethyl Ether Synthesis from Synthesis Gas

“…The pressure drop of the catalyst bed was measured before and after each experiment using a pressure transducer to confirm insignificant changes in catalyst packing. The micro-structured reactor has been thoroughly studied earlier in our group for methanol [48][49][50], direct DME [51][52][53] and Fischer-Tropsch [54] syntheses, and has been established as practically isothermal, isobaric and free from mass transfer limitations under conditions similar to the ones applied in the present study.…”

Modelling and simulation of a single slit micro packed bed reactor for methanol synthesis

“…For example, packed channels may provide less efficient heat removal as compared to wall-coated ones due to less contact area between the catalyst and the walls [4]. Since true catalyst temperature measurements are difficult [11,17] the development of models to facilitate insight to the temperature distribution within the catalyst bed in microreactors is relevant. Such models could also be used to provide indepth understanding of reactor performance under different operating conditions and hence be applied for further improvement of heat and mass transfer.…”

“…They also investigated Fischer-Tropsch synthesis in a microchannel reactor [19] and demonstrated capability of these reactors for improved heat removal and enhanced productivity with less selectivity to methane. Hayer et al [17] applied a 2D-dispersion model to represent a micro-packed bed reactor for direct DME synthesis. They demonstrated superior heat removal capability of the reactor at typical operating conditions of a direct DME process.…”

“…In previous publications we have performed experimental investigations on different aspects of methanol synthesis from synthesis gas in an Integrated Micro Packed Bed Reactor-Heat Exchanger (IMPBRHE) [11,17,20]. The purpose of this paper is to describe the advanced transfer characteristics of the IMPBRHE observed in the experimental work through a model that includes the main governing phenomena involved.…”