Research On The Characteristics Of Mixed Molding Of Waste Plastics And Biomass-pyrolysis Into Charcoal

The conversion of biomass into high quality biomass charcoal by pyrolysis is one of the effective ways to improve the quality of biomass energy.In order to prepare high-grade molded biomass charcoal with high value and strong physical properties,this paper uses biomass formed by mixing waste plastic and pine wood chips as raw materials,and selects the best molding conditions for pyrolysis into carbon.?1?The physical properties of molded biomass are affected by factors such as raw material mixing ratio,molding heating rate,final molding temperature,molding pressure and other factors.Under the same molding heating rate,the relaxation density of the molding biomass increased with the increase of the mass fraction of pine sawdust.Under the same mixing ratio,too fast molding heating rate is unfavorable to biomass strength,and the increase of heating rate leads to a sharp decline in the tumbling strength of the molding biomass.Under the same final temperature of molding,the content of pine wood chips had no obvious effect on the crash-resistance strength of the molding biomass,while the addition of waste plastics significantly improved the relaxation density of the molding biomass hot pressing.Under the same mixing ratio,too low molding final temperature will lead to a significant decrease in the relaxation density and anti-crash strength of the molded biomass,while too high molding pressure will damage the internal structure of the molded biomass and reduce its physical properties.Considering comprehensively,the optimal parameters for the mixing molding of waste plastics and pine wood chips are as follows:the mass ratio of pine wood chips/waste plastic is 3:1,the molding heating rate is 20?/min,the final molding temperature is 150?,and the molding pressure is 15MPa.?2?The effects of the mixing ratio of pine sawdust and waste plastic and the pyrolysis temperature on the pore structure and heat value of the molding-pyrolysis carbon were analyzed in N2 atmosphere.The results showed that the pyrolysis temperature determined the pore structure of biomass carbon,and the addition of plastics increased the heat value of biomass carbon,but too much addition would damage the pore structure of biomass carbon.When it is lower than 500?,the pore formation rate of biomass charcoal is poor and the micropore is small.When the temperature is higher than 500?,the specific surface area of biomass carbon increases from 50.559 m²·g^-1,50.833 m²·g^-1,and 70.001 m²·g^-1 to 103.216 m²·g^-1,116.290 m²·g^-1,and 227.896 m²·g^-1,respectively,with the increase of pyrolysis temperature.When the pyrolysis temperature is 600?,the proper addition of waste plastics helps to increase the heat value of biomass charcoal.When the pine sawdust/waste plastics is 3:1,the heat value increases from 25.1217 MJ·kg^-1 of pure sawdust to 30.2419 MJ·kg^-1,and does not affect the porous pore structure of biomass charcoal.However,as the pyrolysis temperature continues to rise to 700?,the pore structure of carbon collapses,the activity of alkaline substances in the pyrolysis carbon decreases,the combustion performance deteriorates,and the heat value decreases.?3?TG and DTG were used to study and analyze the combustion characteristics of biomass pyrolysis carbon with plastic added.The comprehensive combustion performance S value of pyrolytic carbon decreases with the increase of waste plastics added in the raw material,among which the S value of pure wood chips pyrolyzed into carbon is t.he highest,which is 8.02×10¹¹.Adding waste plastics will change the combustion process of molding biomass charcoal.The combustion mechanism of biomass charcoal prepared by pure wood chips is spherical internal diffusion combustion,while that of biomass charcoal added with waste plastics is spherical chemical reaction control combustion mechanism.By comparing the best pyrolysis under the condition of forming block and grind into powder of pyrolytic carbon dynamics analysis,forming the massive biomass char combustion reaction mechanism is divided into three sections:the temperature is 393??466?,the combustion reaction mechanism function for cylindrical internal diffusion mechanism,the temperature is 467??597?,the reaction mechanism for the spherical chemical reaction control mechanism,the temperature is 598??697?,the combustion reaction mechanism for chip internal diffusion control mechanism.