Research On Combustion And Pollutant Characteristics Of Civil Blended Briquette

Civil coal combustion has a serious impact on the atmospheric environment.Briquette technology can effectively reduce the emission of pollutants from coal combustion.As a widely used means to improve the characteristics and emission of coal combustion,coal blending is rarely used to study civil briquette.Through coal quality analysis,a large number of coal blending thermobalance experiments and blended briquette combustion experiments simulating the actual situation,this paper studies the influence of coal blending on the actual briquette combustion and emission,and provides guidance for the actual civil briquette blending scheme.The experimental results show that when the particle size of Xiyang coal,Shouyang coal and Youhun coal is less than 6mm,the difference of coal quality and combustion characteristics is very small.The average variation range of ignition temperature and burnout temperature is about2%.Through the thermobalance experiment of 7 kinds of raw coal and 23 kinds of blended coal including Xiyang coal and Youhun coal,it is found that the thermogravimetric combustion curve of blended coal can be obtained by linear superposition of the thermogravimetric curve of raw coal,and the correlation coefficient between the thermogravimetric curve and the calculated curve is more than 0.999.Xiyang coal and Youhun coal were blended to carry out briquette combustion experiment on the self-designed civil briquette experimental platform,and the combustion characteristics and pollutant emission characteristics of blended briquette were studied.The results show that the peak temperature of flue gas at the furnace outlet is equivalent to that of Youhun coal when the blended coal is 30%,and the average time difference is reduced by 15.6%compared with the pure Xiyang coal;the peak temperature has a linear positive correlation with the blending proportion,and the heating rate increases with the increase of the blending proportion,and the heating rate increase rate of Youhun coal is 152.7%;the blending of Youhun coal is beneficial to improve the burnout rate.In addition,the highest increase rate is 31.9%when the blending ratio is 30%.In terms of pollutant emission characteristics,the SO₂ emission of Xiyang coal is far less than that of Youhun coal;the conversion rate of gaseous sulfur increases to 16%with 30%blended coal,and 36%with 50%blended coal;the no emission concentration of Youhun coal is more than4 times of that of Xiyang coal.With the increase of the proportion of Youhun coal in Xiyang coal,the mass concentration of SO₂ and no also increases.The emission of particulate matter is concentrated in the ignition stage,and almost no particulate matter is produced in the peak stage.The change of PM₁ emission factor will change with the proportion of PM₁.When the blending proportion is 30%,the emission peak and duration of PM_2.5 are similar to those of Xiyang coal;when the blending proportion is 50%,the emission peak of PM_2.5 is similar to that of Youhun coal;the emission duration of PM₁₀ is almost the same as that of PM_2.5.