FEASIBILITY ANALYSIS OF TERNARY FEED MIXTURES OF METHANE WITH OXYGEN,STEAM, AND CARBON-DIOXIDE FOR THE PRODUCTION OF METHANOL SYNTHESIS GAS

The feasibility of ternary feed mixtures of CH4 with O-2, H2O, and CO2 is analyzed in relation to the production of methanol syngas. Stoichi ometric constraints are formulated in terms of three parameters charac terizing the steam, partial oxidation, and carbon dioxide reforming re actions of methane. The equilibrium analysis is conducted using the me thanol balance ratio mu and methane slip fraction chi as explicit desi gn parameters. General results are derived for the feasibility of each ternary feed combination as a function of pressure and temperature in the range 1 < mu < 3 under carbon-free conditions. Numerical calculat ions indicate that CH4/O-2/CO2 feeds can be used in single-stage adiab atic reformers at low values of mu, but the produced syngas requires f urther treatment. Reforming based on CH4/O-2/H2O feeds is endothermic at mu greater than or equal to 2 under typical reaction conditions, th us requiring the application of a two-stage process involving primary and secondary reformers. Utilization of CH4/O-2/H2O feeds in single-st age adiabatic reactors is feasible for mu = 1.7-1.9, yielding syngas w hich can be upgraded by partial CO2 removal. The endothermic CH4/CO2/H 2O feed combination is always feasible for 1 < mu < 3.