Numerical investigation of the influence of operating parameters on NO_x emission characteristics under oxy-coal combustion atmosphere in a tubular combustor

In this study, NO_x emission characteristics of oxy-coal combustion atmosphere have been thoroughly investigated employing the developed and validated numerical model under oxy-coal combustion atmosphere. The influence of oxy-fuel combustion atmospheres, feed gas inlet temperatures and pressures on the NO_x emission (ppm) characteristics have been studied in detail. Influence of higher concentration steam addition on NO_x emission under oxy-coal combustion atmosphere has also been assessed employing the developed oxy-coal combustion model. Furthermore, a quantitative summary of NO_x emission at the outlet of the combustion chamber under above-mentioned operating conditions have been provided. The result showed that oxy-coal combustion cases having higher O₂ concentration in the oxidizer had produced higher NO_x emission due to an enhanced conversion rate of coal_N to NO_x. The wet oxy-fuel combustion case (10–50% H₂O in the oxidizer) has 2.5%–75% higher NO_x concentration (ppm) compared to the ideal dry-recycle oxy-fuel combustion case (0% H₂O in the oxidizer). The oxy-steam combustion case has 99% higher NO_x concentration (ppm) compared to the ideal dry-recycle oxy-fuel combustion case.