Process Design of a Novel Low Temperature Methanol Synthesis Process Using an Air-blown Autothermal Reformer

Abstract

Methanol (MeOH) synthesis at low temperature (100 oC) presents an opportunity for full syngas conversion per pass. This presents a cheaper alternative for MeOH synthesis using an air-blown autothermal reformer (ATR) rather than the conventional high temperature (>250 oC) MeOH synthesis approach which requires an expensive cryogenic O2-blown ATR. The aim of this work was to use the process simulation program Aspen HYSYS to simulate and optimize the reactor conditions for a complete MeOH process design using an air-blown ATR. Our results revealed that, while syngas produced from ‘normal’ air-blown ATR (syngas composition 0.20CO:0.40H2:0.39N2) required 100 bar to obtain full conversion per pass, syngas produced from enriched airblown ATR (syngas composition 0.31CO:0.62H2:0.07 N2) required 60 bar total syngas pressure to achieve the same. Even though the energy generated in both processes was enough to cover the heating demand in the total process with surplus, the enriched air-blown system provides a better energy recovery if the surplus energy is not used for extra power generation. The total process energy demand due to compression was estimated to be 2270 and 983 MJ/ton MeOH product for the normal air-blown and enriched air-blown systems respectively. A process design was proposed based on the optimized conditions for the enriched air-blown process.