Study On Co-combustion Kinetics And Pollutant Emission Characteristics Of Phoenix Tree's Leaves And Their Biochar With Coal

Through the thermal gravimetric experiments at different heating rates,the combustion characteristics of phoenix tree's leaves and their two kinds of biomass char were studied respectively.The results showed that DTG curves of phoenix tree's leaves and hydrothermal carbon showed four mass loss peaks and pyrolytic carbon peaked at three peaks.The rate of heating has a small effect on the burnout of the sample.But it has a significant effect on the burning rate.Phoenix tree's leaves and hydrothermal carbon's intergrated combustion characteristic index S_N are high,and the ignition temperature and burnout temperature are low.Hydrothermal carbon are more suitable for use as biomass fuels because they are easier to store and transport.The combustion kinetics was analyzed based on the distributed Coats-Redfern(modified)method.The results show that the activation energy distribution of the combustion process is in the form of'N'.The activation energy in the low temperature combustion zone was higher and the activation energy in the high temperature combustion zone was lower.As the heating rate increases,the sample activation energy decreases slightly,but the overall trend remains unchanged.Based on random forest regression model,the prediction models of the activation energies of the coal mixed with the leaves,pyrolytic carbon and hydrothermal carbon were built respectively.The results showed that the R~2 of all three kinds of activation energy prediction models were in the range of 0.9716 to 0.9847,indicating that the predictive value was positively correlated with the test value.MSE were in the range of2.0956 to 5.9433,MAE were in the range of 1.1763 to 2.3000,indicating that the model prediction error is small.EVC were in the range of 0.9743 to 0.9858,indicating that the model can be explained more strongly.The CO and NO emission experiments were conducted in a tube furnace test system at different heating rates.These experiments were conducted to study the effects of sample types,blending ratios and final reaction temperature on CO and NO emissions.At 700?,the CO emission of phoenix tree's leaves and hydrothermal carbon was significantly lower than that of pyrolytic carbon and coal,but the CO emission was significantly higher at 900?.When the combustion temperature is 700?/800?/900?,the NO emission of coal is always the highest.The NO emission of phoenix tree's leaves,pyrolytic carbon and hydrothermal carbon are almost the same,about 40%less than that of coal.The samples were phoenix tree's leaves and their two kinds of biomass char mixed with coal in a 50:50 mixture.When the temperature was at 700?/800?/900?,the CO emission of the mixed samples were greatly reduced both in intensity and duration.However,the NO emission increased first and then decreased with the increase of temperature,but the variation range was smaller.