Study On Pyrolysis Characteristic And Process Parameter Of Pine Nut Shell

There are a wide variety of technologies to utilize biomass in modern world,and the four main categories are respectively direct combustion,thermochemical conversion,biochemistry and liquefaction technology,while it is attached importance to biomass pyrolysis technology belonging to the process of thermochemical conversion,biomass raw materials possesses significant potential as a renewable energy source to be transformed into high-value and high-grade charcoal,bio-oil and combustible gas by pyrolysis method,which has a very broad market prospect by appropriate treatment.In this paper,red pine nut shell in the northeast was considered as raw material of study.In order to research the effects of reaction temperature and reaction time on the yield and quality of pyrolysis products,pyrolytic charcoal,bio-oil and gas products were gained at different reaction temperatures and time by biomass continuous pyrolysis reaction device with a variable pitch spiral conveyor.The structure characterization,chemical composition and properties of pyrolysis products were in-depth analyzed,which provided theoretical basis for experimental study of pine nut shell continuous pyrolysis.The work was summarized as follows:(1)Biomass raw material was investigated by basal composition analysis and thermo-gravimetric analysis(TGA),and the range of reaction temperature and time was determined.The conditions of experiment on biomass continuous pyrolysis were conducted at different reaction temperatures(300?.400?.500?.600? and 700?)and different reaction time(4min?6min?8min?10min and 12min).(2)The charcoal was gained from pine nut shell pyrolysis,its yield and trends of indicators under different pyrolysis process conditions were investigated,and its characterization was thoroughly studied.The results were as follows:with pyrolysis temperature increasing,the yield of pyrolytic charcoal decreased rapidly;the content of ash increased slowly and the content of fixed carbon increased quickly;while the content of volatile decreased rapidly;heating value of pyrolytic charcoal first increased quickly until the temperature reached about 600?,which got the maximum heating value,then reduced gradually;and adsorption value of iodine was up to maximum at about 500? at first,then decreased;the density of pyrolytic charcoal showed a decreasing trend.Compared with the reaction temperature,the influence of pyrolysis time on the yield and trends of indicators of pyrolytic charcoal was not apparent;pore structure of charcoal was more developed at 500 ? than other temperatures.(3)The bio-oil was got from pine nut shell pyrolysis,its yield and trends of indicators under different pyrolysis process conditions were investigated,and its chemical composition and properties were studied in detail.The results were as follows:with pyrolysis temperature increasing,the yields of bio-oil and wood vinegar first increased until the temperature reached 500? which got the maximum yield respectively,then reduced with temperatures further rising,and water content and the viscosity of wood vinegar reduced gradually;and pH value also appeared an slow decreasing,while the yield of tar continued to rise,which got high yield when the temperature was about 500 ?;heating value of tar was soon up to maximum at about 600? at first,then decreased quickly,but the viscosity and pH value of tar showed declining trends by different degrees.Compared with the reaction temperature,the influence of pyrolysis time on the yield and trends of indicators of bio-oil was not evident.In addition,it indicated that wood vinegar was prepared on the condition that pyrolysis temperature was 500 ? and pyrolysis time was 8min;its main ingredients were phenols and ketones,respectively 53.88%and 20.93%;the tar obtained on the same pyrolysis condition mainly included phenols and aldehydes,respectively 60.76%and 8.98%.The rate that wood vinegar received at 500? 8min scavenges hydroxyl radical was 66.63%,which showed that the wood vinegar possessed evident scavenging action to hydroxyl radical,had strong antioxidant activity;pH value of wood vinegar gained at 500 ?,8min was low,but had weak corrosion.(4)The gas product was gained from pine nut shell pyrolysis,its yield and trends of indicators under different pyrolysis process conditions were investigated,and its composition was thoroughly studied.The results were as follows:with pyrolysis temperature increasing,the yield of pyrolytic gas increased rapidly;H2 showed the same trend;the yield of CO rose first until the temperature reached about 500?,which got the maximum yield,then reduced gradually;the yield of CH4 increased rapidly;the yield of CO2 decreased rapidly;the yield of C2H4 and C2H6 increased by degrees;heating value of pyrolytic gas increased in a short time.Compared with the reaction temperature,the influence of pyrolysis time on the yield and trends of indicators of pyrolytic gas was not obvious.