Oxy-fuel combustion based enhancement of the tri-reforming coupled methanol production process for CO2 valorization

Abstract

Capture and conversion of carbon dioxide from fossil fuel power generation systems is an important consideration. Tri-reforming of combustion exhausts (i.e. flue gas) with methane, which avoids the capture step, so as to produce synthesis gas for methanol production, has been proposed as a viable CO2 valorization alternative for conventional air-combustion systems. However, the presence of nitrogen that is not a reactive component results in increased reactor sizes and decreased efficacy of the tri-reforming based process. In this paper, we explore the use of tri-reforming with an oxy-fuel combustion process, where the nitrogen content of the combustion exhaust gas is considerably reduced, and therefore a carbon dioxide enriched feed is utilized for the tri-reforming coupled methanol production process. Also, to support the oxy-fuel combustion process, we propose utilization of water electrolysis as an oxygen source, while also utilizing the generated hydrogen in the downstream methanol production. The main contributions of this paper are therefore (i) the proposition of combining oxy-fuel combustion with the tri-reforming coupled methanol production process to mitigate the above drawback, and (ii) utilization of water electrolysis as a source of oxygen and an evaluation of the impact of the generated hydrogen on the CO2 valorization potential of the process. These two propositions have been implemented as process improvements on the conventional tri-reforming coupled methanol process. The resultant processes have been simulated using Aspen Plus V8.4, optimized and compared in this paper to justify their efficacy.