Numerical simulation and cold experimental research of a low-NOx combustion technology for pulverized low-volatile coal

Large quantities of low-volatile coal are utilized in power plants throughout China. With increasingly stringent environmental regulations, it is important to develop and deploy low-NOx combustion technologies for pulverized coal boilers burning low-volatile coal. The objective of this study was to investigate a novel decoupling combustion system for low-volatile coal via experiments and computational fluid dynamics (CFD). The combustion system includes horizontal fuel-rich/lean low-NOx burners (LNB) and the associated air distribution system for a polygonal tangentially fired boiler (PTFB). The effects of coal particle diameter and coal feeding rate on the gas/particle flow characteristics of the burner, and the cold state aerodynamic field of the PTFB were analyzed in detail. The structural design of the LNB results in advantageous gas/particle flow characteristics and the PTFB improved the distribution of the flow field. The CFD models and simulation results were validated by comparing with those of cold experiments data. The simulation results demonstrated that this low-NOx combustion technology enhances staged combustion at different scales, which can reduce NOx generation significantly. In the industrial application on a 300 MW pulverized coal boiler, installation of the LNBs improved the stability of low-volatile coal combustion and reduced NOx emissions significantly. These research findings provide valuable guidance to the design of low-NOx combustion system for pulverized coal boilers using low volatile coal.