Thermodynamic Study of Associated Petroleum Gas Reforming to Methane

The equilibrium constants and heats of reactions of reforming of associated petroleum gas (APG) with different concentrations of methane homologues in the temperature range of 300-475 degrees C have been calculated. It has been shown that methanation proceeds in two stages, one of which is the hydrogenolysis of methane homologues. The effect of parameters (temperature, pressure, APG composition) on the equilibrium composition of pre-reforming products, autothermality, and the formation of elemental carbon has been examined. The calculations have been carried out with allowance for nonideality of the gas components (Peng-Robinson model) in the temperature range of 350-450 degrees C at a pressure of 0.1-2.0 MPa. It has been found that at 350-400 degrees C and a pressure of 2.0 MPa, the autothermal reforming of methane homologues is theoretically possible at a steam : gas ratio of 1 : (1-1.25) (for APG with a methane equivalent of 1.8 to 2.6). With such parameters, the formation of elemental carbon is thermodynamically impossible.