Application of response surface methodology for optimization of purge gas recycling to an industrial reactor for conversion of CO2 to methanol

Nowadays, by the increasing attention to environment and high rate of fuel production, recycling of purge gas as reactant to a reactor is highly considered. In this study, it is proposed that the purge gases of methanol production unit, which are approximately 15.018 t·h^-1 in the largest methanol production complexes in the world, can be recycled to the reactor and utilized for increasing the production rate. Purge gas streams contain 63% hydrogen, 20% carbon monoxide and carbon dioxide as reactants and 17% nitrogen and methane as inert. The recycling effect of beneficial components on methanol production rate has been investigated in this study. Simulation results show that methanol production enhances by recycling just hydrogen, carbon dioxide and carbon monoxide which is an effective configuration among the others. It is named as Desired Recycle Configuration (DRC) in this study. The optimum fraction of returning purge gas is calculated via one dimensional modeling of process and Response Surface Methodology (RSM) is applied to maximize the methanol flow rate and minimize the carbon dioxide flow rate. Simulation results illustrate that methanol flow rate increases by 0.106% in DRC compared to Conventional Recycle Configuration (CRC) which therefore shows the superiority of applying DRC to CRC.