School of Environmental Science and Engineering, Tianjin University
CHN Energy New Energy Technology Research InstituteCo., Ltd.
Department of Thermal Engineering,Xi’an Jiaotong University
Institute of Thermal EnergyEngineering, Shanghai Jiaotong University

Co⁃firing of carbon⁃neutral biomass with coal is the most economic and promising technology to reduce CO2emission from coal combustion currently. Limited by the biomass distribution feature and collection cost in China, thebiomass co⁃firing in large⁃scale coal power plants can only be at a small ratio of biomass. However, for the industrialboilers used for distributing energy system, it is able to co⁃fire biomass at a high ratio and even purely burn biomass.Biomass combustion in the grate furnace and circulated fluidized bed has been widely adopted, in contrast, the studyand application of biomass co⁃firing in the pulverized coal industrial boilers of higher efficiency and automation degreeat a high⁃ratio is rare. In this paper, the biomass high⁃ratio co⁃firing in a new developed pre⁃pyrolysis pulverized coalindustrial boiler is studied. The effects of biomass co⁃firing ratio on temperature distribution, wall heat flux, spe⁃cie distribution and NOx emission are discussed. The CFD modeling results show that biomass co⁃firing or evenpure combustion follows the similar temperature and specie distribution of pure coal combustion. With the increase ofbiomass co⁃firing ratio, the combustion in the primary zone is strengthened, however, due to the higher moisture con⁃tent in biomass, the flame is overall delayed, the oxygen consumption rate decreases, and the volatile and CO concen⁃trations increases in the primary combustion zone. Because of the dual effects from flame delay and higher nitro⁃gen content in biomass, with the increase of biomass co⁃firing ratio, the NOx emission increases first and then decrea⁃ses. This study indicates that the pre⁃pyrolysis pulverized coal combustion technology is feasible to co⁃fire biomass ata high ratio and even hundred percent. When the nitrogen content of biomass is controlled, the NOx emission can besignificantly reduced by biomass co⁃firing.