Journals Proceedings

Abstract

This study investigates numerically the NOx reduction by SNCR in a CO boiler. The combustion and fluid flow in the FPC CO boiler is examined with emphasis on the effects of injection amount and hole size of reducing agent on NOx reduction. Simulation results indicate that NOx is formed mainly in the high temperature region near the boiler inlet where the mixing caused by swirler is strong. When reducing agent is injected from the boiler inlet, NOx reduction efficiency increases with the amount of reducing agent but gradually levels off. When the amount of reducing agent is increased to 2.5 times the default value, NOx reduction efficiency is 53%. On the other hand, when reducing agent is injected from 3.6m behind the boiler inlet, NOx concentration is not significantly influenced by the amount of reducing agent injected. Finally, when reducing agent is injected from the boiler inlet, the best NOx reduction efficiency is achieved when the size of reducing agent injection hole is the smallest. However, on the condition of fixed amount of reducing agent injected, NOx concentration is not significantly influenced by the injection hole size of reducing agent. On the other hand, when reducing agent is injected from 3.6m behind the boiler inlet, NOx concentration is not significantly influenced by the injection hole size of reducing agent.