Study On Physicochemical Properties And Emissions Of Densified Biofuels

Nowadays,the rapid development of biomss densified technology provides a good solution for those problems.But the quality of densified biofuel is not well.On the other hand,there is no relevant standards in emissions of densified biofuel.Thus,the paper studied the quality and combustion emissions of densified biofuel with typical biomass raw materials,aiming to improve the quality of biofuel and provide references for the later research and standards on emissions of biofuel.Firstly,we studied the effect of moisture on the physicochemical of densified pellets based on the LJ-470 pellet mill with horizontal and ring type die by using corn stalks,peanut shell and pine sawdust as raw materials.The results showed that the maximum density of pine sawdust,corn stalk and peanut shell were about 1180kg/m³,1220kg/m³and 1130kg/m³,the maximum drop resistance were 80%?97.02%and 71.6%,the maximum deformation resistance were 0.46 KN?1.37 KN and 1.07 KN,when the moisture content is 12%?12%?14%,respectively.It was also found that the comprehensive combustion index?14.03?of corn straw biofuel was better than that of pine sawdust biofuel?11.1?and peanut shell biofuel?10?based on the comparison of combustion performance analysis.Secondly,experiment of combustion emission with corn stalk biofuel was conducted on a domestic biomass heating stove.The effect of feed rate,volume of intake air and induced air?pressure in furnace?on the emissions of CO,CO₂,NO and NO₂ were studied.The results were as follows:The emission of CO increases with the increase of the intake air volume.The NO_xemissions are mainly consist of NO.As the induced air volume increases,in other words,pressure in furnace becomes lower gradually,NO and CO₂ emissions decrease accordingly.But the increase in the feed rate also promotes the NO and CO₂emissions.The combustion performance was good when the feed rate is 1 kg/h,the air intake is 0 mg/m³,and the furnace pressure is-15 Pa.Meanwhile,the emissions of CO,NO,NO₂and CO₂were 1493.82 mg/m³,76.63 mg/m³,23.53 mg/m³ and 1.35%.The combustion performance was good when the feed rate is 2 kg/h,the air intake is 0.6 mg/m³,and the furnace pressure is-15 Pa.At the same time,the emissions of CO,NO,NO₂ and CO₂were1133 mg/m³,170.5 mg/m³,11.88 mg/m³ and 3.27%.The combustion performance was good when the feed rate is 2 kg/h,the air intake is 0 mg/m³,and the furnace pressure is-25 Pa.Furthermore,the emissions of CO,NO,NO₂ and CO₂were 1064 mg/m³,217.57 mg/m³,26.81mg/m³ and 5.72%.Finally,under the better and worse combustion conditions,comparative experiments of temperature of the intake air,furnace and smoke were conducted.The results showed that the smoke temperature was higher under the better condition than the worse,and there were no differences elsewhere.From the characterization analysis of ash content of corn stalk biofuel after combustion,it was found that it mainly contains KCl,Si O₂,K₂SO₄,Ca CO₃ and other components.The slagging phenomenon was closely related to the combustion conditions.