Numerical study of NOx formation during incineration of cellulosic and plastic materials: The combustion regime

A numerical model has been developed (Chemkin) to study combustion processes in a fixed-bed reactor. The test section is divided into several successive Perfect Stirred Reactor (PSR). At the entry, the thermal degradation species of the solid are used as input and at the exit the exhaust gases are recovered. Comparison of previously experimental results and the current model output has been compared with good agreement. The model has been used to establish the reaction pathways at different locations in the reactor. This has allowed defining what is occurring at each specific location of the reactor. A sensitivity study has been conducted varying the different operating parameters. The reaction pathways and sensitivity study have shown that the production of NO is controlled mostly by local oxygen concentration, thus the location of the NO production region depends mostly on the primary air injection. Temperature can have a significant effect on the global NO output, but only if enough oxygen is available for the reactions to proceed. Reduction reactions appear almost insensitive to temperature.