Combustion and reformulation characteristics of biogas in plasma assisted combustion using microwave induced non-equilibrium plasma

To utilize biogas validly, we have applied plasma assisted combustion using microwave to the combustion and reformulation of biogas. In this study, the characteristics of combustion and reformulation of biogas have been investigated by comparing of large and small nozzle. In case of small nozzle, the combustion and reformulation of biogas stably occurs over a wider equivalence ratio area than that in case of large nozzle, because the damping of microwave is inhibited. N₂ and OH radical decrease, and H, CO, CH and C₂ radicals increase as equivalence ratio. H₂ and CO concentrations increase, and CO₂ concentration decreases with increasing equivalence ratio. In this method, since the reaction of CO₂ + e → CO + O occurs, the amount of CO₂ of produced gas is less than the amount of supplied CO₂ in high equivalence ratio region. Cold gas efficiency increases with increasing H₂ and CO concentrations. When CH₄ is completely reformed into H₂ and CO, cold gas efficiency is about 95 %. However, the maximum value of cold gas efficiency is approximately 110 % at small nozzle, because CO₂, which does not have calorific value, is decomposed into CO, which has calorific value.