An investigation to define the physical/chemical constraints which limit NO sub x emission reduction achievable by reburning

Abstract

Reburning is a combustion modification technique which removes NO{sub x} from combustion products by using fuel as a reducing agent. Previous studies have shown that natural gas is more effective than coal as a reburning fuel. Objectives of this program are to define the chemical and physical constraints which prevent the attainment of 80% NO{sub x} reduction with reburning and to test improved configurations for reburning as an advanced NO{sub x} control technique for coal-fired boilers. Bench scale studies are designed to screen the chemical and physical means for enhancing reburning efficiency. Pilot studies will evaluate the impacts of finite rate mixing on the effectiveness of the various concepts. The program consists of the following: bench scale studies of N{sub 2} formation in reburning zone and XN conversion in burnout zone; pilot scale studies; interpretation and generalization, and a final report. This report documents the experimental results obtained in the bench scale studies. The focus is on the chemistry of N{sub 2} formation in the reburning zone. Experiments were conducted in the bench scale Control Temperature Tower (CTT).