The influence of generator gas composition on pollutant emissions

PURPOSE. Determination of quantitative characteristics of nitrogen oxide emissions during combustion of gas mixtures containing hydrogen, carbon monoxide and methane.
RESULTS. Several types of gases with different chemical compositions and quantitative content of components were considered: CH₄; CO; H₂; 7 types of synthesis gas with different content of CH₄, CO, H₂, CO₂, N₂. These types of synthesis gas had low, medium and high values of heat of combustion. When performing numerical studies of the parameters and composition of combustion products, an approach based on the chemical equilibrium state of a multicomponent reacting mixture at a minimum value of isobaric-isothermal potential was used. The values of the main parameters of combustion products and estimates of nitrogen oxide emissions were obtained at different ratios of the initial components in the gas mixture and different values of the excess air coefficient. The values of the relative indicators of combustion product consumption correlate quite strongly with the values of the relative indicators of nitrogen oxide emissions.
CONCLUSION. Numerical estimates of the relationship between the combustion heat of generator gases, the flow characteristics of the combustion products determined by the composition of the initial gas mixture, and nitrogen oxide emissions are obtained. The quantitative indicator W_ps, determined by the ratio of the mass flow rates of the combustion products of the base fuel and alternative generator gas, under the condition of the same thermal power of the power plant, makes it possible to preliminary compare the expected level of NO_x emissions. At W_ps ≈ 1, the level of NO_x emissions for the compared fuel compositions is approximately the same. Accordingly, at values of this indicator greater or less than one, the levels of nitrogen oxide emissions during combustion of the alternative generator gas are higher or lower than during combustion of the base fuel. The practical use of the W_ps indicator is most effective at the stages of development and design of new power plants, including optimization of planning of computational and full-scale experiments, as well as during the transfer of operating power plants to alternative gas fuel.

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