Hydrogen and carbon dioxide recovery from the petrochemical flare gas to methanol production using adsorption and absorption combined high-efficient method

Abstract

Today, one of the challenging issues all over the world is the global warming which can be attributed to the emission of greenhouse gases into the environment as well as burning of gases in flare gas stream of industrial units. The latter can not only cause environmental problems but also is accompanied by wasting a great deal of energy. To deal with the aforementioned issue, the flare gas stream can be recycled after separating some species. In this investigation, the objective is to separate CO2 and H2 from the flare gas in addition to methanol production. In this regard, a separation with sorbent/solvent method is used which is divided into two stages: (1) H2 separation by sorbent, (2) CO2 separation by monoethanolamine solvent. From the obtained results in this study, in the first stage, H2 and CO2 can be purified up to 75% and 99.83%, respectively. Beside, methanol synthesis is compared in three different cases: (1) industrial unit, (2) CO2 is fed into the reactor instead of CO, and (3) CO2 and H2 are fed to the reactor with stoichiometric coefficients. The obtained methanol production of the case (1) is approximately close to that of the case (3) and it is reduced 4% in case (3).