| Shaanxi province is the best apple production area worldwide,accounting for nearly 1/3 of the total planting area in China and 1/7 of the world,respectively.Each year,near 5 million T of the dry apple pruning braches are produced in Shaanxi.Carbonization as a way of thermochemical conversion of the pruning apple branches can generate two types of clean and renewable energy simultaneously:including biocarbon and pyrolysis gas,which has great potential in solving environmental pollution in rural areas,reducing the rural energy supply pressure,and expanding the resource recycling and utilization.In this study,based on our previous research results of reaction temperature effects on carbonization of the three components of biomass,we use apple pruning branch as the research object to investigate the influence of pyrolysis temperature,heating rate,and holding time on the characteristics of biocarbon and pyrolysis through the analysis of single factor test and response surface experimental designs.The results could provide experimental and technical support reference for the retorting of apple pruning branches in future.The main conclusions of this thesis are listed as follows:?1?Taking biomass three components as experimental object,the effect of temperature on the carbonization characteristics of biomass three component preparation of biochar was studied.The results were shown as follows:wth the increase in temperature,the yield of biochar,volatile content,and the content of H,O,N obtained from carbonization of cellulose,hemicellulose and lignin decreased gradually,while the ash content,fixed carbon,calorific value and C content increased gradually.When the temperature was at 500 oC,biochar from cellulose and hemicellulose processed optimal specific surface area,micropore volume,and the maximum iodine adsorption values of 422.46 mg/g and 115.06 mg/g,respectively.When the temperature reached 600 oC,biochar form lignin showed the optimal specific surface area,micropore volume,and the maximum iodine value of 460.35 mg/g.?2?The effects of temperature,heating rate and holding time on the characteristics of biochar obtained through carbonization of Apple pruning branches were studied.The results were shown as follows:with the increase in temperature,the biochar yield and volatile matter gradually decreased,the ash content gradually increased,the fixed carbon content increased first and then decreased.With the increase of heating rate,the biochar yield,the ash content and the fixed carbon gradually decreased,and the volatile content increased gradually.With the elongation of the holding time,the biochar yield and the volatile content gradually decreased,the ash content and the fixed carbon gradually increased.Temperature,heating rate and holding time showd significant main effect on the biocarbon yield,the effect of temperature and holding time on the biochar yield and fixed carbon content showed interaction.In these interaction,under each of the following three cases:the temperature between 500 oC530 oC,the heating rate of 2 oC/min3 oC/min;the temperature between 500 oC530 oC,the holding time of 170 min180 min;the minimum heating rate and the longest holding time,the fixed carbon in biocarbon can reach the maximum value higher.?3?The effects of temperature,heating rate and holding time on the characteristics of pyrolysis gas obtained through carbonization of Apple pruning branches were studied.The results were shown as follows:With the increase in temperature,the pyrolysis gas yield decreased gradually,and the calorific value of the product gas increased first and then decreased,the CO content decreased first and then increased,the CO2 content decreased gradually,the CH4 content increased first and then decreased,the H2content increased gradually.With the increase in heating rate,the pyrolysis gas yield gradually decreased,and its calorific value did not change,the CO content increased gradually,the CO2 content gradually decreased,the CH4 content decreased first and then increased,the H2 content increased first and then decreased.With the elongation of the holding time,the pyrolysis gas yield gradually increased,and its calorific value did not change,the CO content decreased first and then increased,the CO2 and CH4 content gradually decreased,the H2 content gradually increased.Under these interactions in their respective range,in each of the following three cases:the maximum temperature and the minimum heating rate,the maximum temperature and the longest holding time;the minimum heating rate and the longest holding time,the pyrolysis gas yield reached the maximum value. |
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