The interaction of fuel-bound nitrogen and fuel-bound chlorine during air-staged incineration

The simultaneous air-staged combustion of methyl amine (CH₃NH₂) and methyl chloride (CH₃CL) was studied in a two zone turbulent flow reactor at atmospheric pressure. The temperature in the first stage was held constant at 1750 K. The feed consisted of ethylene (C₂H₄), CH₃NH₂, CH₃Cl, air and N₂ (for first stage temperature control). Fuel-lean and fuel-rich mixtures were fed into the first stage. During the fuel-rich feed runs, secondary air was injected into the second stage to make the overall system fuel-lean. Measurements of species including NO, CO, CO₂ and O₂ were made in both stages. Three major observations were made: 1) The addition of CH₃Cl during air staged combustion of CH₃NH₂ does not alter the attainment of an NO minimum emission from the second stage; 2) The optimal first stage equivalence ration corresponding to the minimum NO in the second stage outlet is approximately 1.3 in both cases; and 3) The minimum NO emission level from air staged combustion significantly decreases when CH₃Cl is added to the feed at constant equivalence ratio. A perfectly stirred - plug flow sequential reactor simulation is used with a detailed chemical reaction mechanism to model the observed species concentrations. The experimental data are well predicted, especially the staged combustion NO minimums. Model-based rate of production calculations suggests that the loss of OH radicals via OH + HCl = H₂O + Cl and the consumption of N radicals via N + Cl + M = NCl + M slow the reaction N + OH = NO + H, leading to the reduced NO minimum emission during the simultaneous air-staged combustion of the fuel-bound chlorine and nitrogen species.