An oxy-fuel combustion based tri-reforming coupled methanol production process with improved hydrogen utilization

CO2 valorization has been identified as an alternative to sequestration in view of its significant economic potential. The first pre-requisite in most of the CO2 valorization processes is an energy consuming capture step, which is avoided in the tri-reforming process. However, direct utilization of flue gas also posed a problem due to the presence of non-reactive nitrogen which severely limited its process efficacy. Coupling of the conventional process with an oxygen-oxidant based power plant addressed this problem in an earlier study where coupling of water electrolysis process supported the upstream plant while furthering the CO2 valorization objective (Dwivedi et al., 2018). This paper further addresses three aspects of the proposed valorization process: (i) low in-reactor hydrogen utilization, (ii) lower profit metric, and (iii) atmospheric pressure operation (that inevitably lead to large reactor sizes) of the tri-reformer. The following contributions have therefore been made in this paper: (i) evaluation of the role of tri-reforming reactor pressure on the relative performance of the modified process over the conventional process, at higher tri-reforming reactor pressures, and (ii) improved the process efficacy in terms of in-reactor hydrogen utilization (from approximate to 30 % to 81.61 %) of the coupled process (by employing higher pressure in the tri-reformer and a two-staged methanol reactor setup) thereby mitigating the major drawback of lower profit metric with respect to the conventional process. Simulation runs of the modified and conventional processes have been executed in Aspen Plus V8.4 in order to establish their relative efficacy.