Study On Piecewise Combustion Kinetics Of Briquette And NO Release Under Different Combustion Modes

Coal is a traditional fossil fuel which account for 59% of primary energy in China.The annual bulk coal consumption in China is about 600 million tons,being 20% of the total coal consumption.Due to lack of pollutants control measures,e emissions from bulk coal combustion is up to 15 times that of power plants.More seriously,the emission height is very low,these in all have a significant impact on environment.Briquetting is a clean utilization of bulk coal,which can improve the efficiency of bulk coal utilization and reduce pollutant emission.To provide some ideas for the development of clean briquette suitable for civilian decoupling furnaces,NO emission tendency of briquette under different manufacturing conditions was studied.In this paper,the large-dose thermobalance was used to explore the kinetics of briquette combustion.Meanwhile the emission reduction mechanism of briquette selfdecoupling and decoupling combustion in the whole furnace was explained.The effects of briquetting pressure,briquette quality,binder type,bulk coal type,and the ratio of the biomass briquette on the pollutant emission were explored employing different combustion technologies in the double-layer fixed-bed.The main conclusions are as follows:1.The large-dose thermobalance and the Coats-Redfern integration method are used to investigate the influence of heating rate,briquette forming pressure,the quality of briquette and the type of coal on weight loss and segmented apparent activation energy of briquette combustion.The results show that the decrease of the heating rate,the sample quality,and volatile content in samples can all increase the activation energy of the volatilization at different extents.2.Results of traditional combustion and the calculated kinetic parameters confirm the existence of the self-decoupling effect of briquette.Compared with pulverized coal,the NO emitted from briquette combustion of has been reduced.Larger briquette size leads to less NO emission is more distinctive self-decoupling phenomenon.3.NO emission adopting different combustion technologies is affected by both the volatile and N content in the fuel.The amount of NO during traditional combustion is mainly determined by the N content of the fuel.For traditional combustion,6.0 g of bulk coal and 80 k N of forming pressure form the NMP briquette with highest denitrification efficiency and discharges NO 3.22% lower than that of pulverized coal.2.0 g of the bulk coal and 80 k N of the forming pressure manufacture the EP briquette with the highest desulfurization efficiency.Different from traditional combustion,the NO emission from decoupling combustion is mainly determined by the volatile content in the fuel.Higher content of volatile results in better denitration efficiency.6.0 g of bulk coal and 60 k N of the forming pressure give rise to denitrification efficiency of up to 40.51% during decoupling combustion of NMP briquette with NO emission 21.09%lower than that of pulverized coal.