The influence of mixing between NH 3 and NO for a De-NOx reaction in the SNCR process

Abstract

The objective of this study was to determine the mixing effect on De-NOx in the selective non-catalytic reduction (SNCR) process using NH 3 as a reductant. A bench scale reactor set-up was used to perform experimental investigations on the mixing in the SNCR process, using an injection of NH 3, with or without an air injection, into the bulk gas. Mixing between NH 3 and NO is a very important parameter, as are kinetic parameters, such as the NSR and reaction temperature. The type of NH 3 with NO mixing method caused different De-NOx results, in which for the case of NH 3 injected with air was more effective for NO reduction than under NH 3 premixing conditions. For the case of air injection conditions, the NO reduction efficiency increased with increasing NSR, initial NO concentration, and retention time. The temperature for the maximum NO removal efficiency was 900 °C with ammonia premixing conditions, but was around 800 °C when ammonia was premixed and air was injected at the same time. That is, the optimization of the reductant mixing and injection conditions are very useful for improving the NO removal efficiency, as well as lowering the reaction temperature to that were optimal efficiency is observed. The optimum momentum ratio ( J), which refers to the mixing characteristics, was found to be about 100 in this study.