Combined reforming and partial oxidation of CO2-containing natural gas using low-temperature gliding arc discharge : effect of stage number of plasma reactors

Abstract

The effect of the stage number of a multistage AC gliding arc discharge system on the system performance of the combined reforming and partial oxidation of simulated CO₂-containing natural gas having a CH₄:C₂H₆:C₃H₈:CO₂ molar ratio of 70:5:5:20 was investigated. For the experiments with partial oxidation, either pure oxygen or air was used as an oxygen source, with a hydrocarbons-to-oxygen molar ratio of 2/1. Without partial oxidation at a fixed feed flow rate, all conversions of hydrocarbons, except CO₂, greatly increased with increasing number of stages from 1 to 3; but beyond 3 stages, the reactant conversions remained almost unchanged. However, for a fixed residence time, only C₃H₈ conversion gradually increased, whereas the conversions of other reactants remained almost unchanged with increasing number of stages. The addition of oxygen was found to significantly enhance the system performance of natural gas reforming. The utilization of air as an oxygen source showed a superior system performance to pure oxygen in terms of reactant conversions, desired product yields and selectivities, and power consumptions. The optimum power consumptions of 3.21x10ˉ¹⁸ Ws per molecule of reactant converted and 2.57x10ˉ¹⁸ Ws per molecule of hydrogen produced were obtained using air as an oxygen source and 3 stages of plasma reactants at a fixed residence time of 4.38 s.