[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk（the ...[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk（the stick and the root）and on the traverse direction（the cuticle,cortex and medulla）.[Result] Cotton stalk is a material of uneven and irregular texture,and there are great differences in the structure of all these parts on the longitudinal and traverse directions,especially in the contents of different components in each layer.The reaction in the stick and root becomes violent along with the increase in the rising rate of temperature,and carbon yield rate decreases in turn.Besides with the same rising rate of temperature,carbon yield rate of cotton stick is higher than the one of cotton root.Carbon yield rates of cuticle,cortex and medulla decrease in turn while the violence of the reaction in cuticle is less severe than in cortex and medulla.[Conclusion] It has provided theoretical basis for obtaining activated carbon technology of cotton stick.展开更多
Two separate experiments were carried out: the first one involved a study of the chemical and some intrinsic feed characteristics of raw cotton stalk( CS) and the efficiency of chemical,biological treatments on the im...Two separate experiments were carried out: the first one involved a study of the chemical and some intrinsic feed characteristics of raw cotton stalk( CS) and the efficiency of chemical,biological treatments on the improvement of the feed value of CS. CS was treated with chemical treatment by mixing 3% Ca( OH)2( CS + Ca),3% urea( CS + U),3% urea +3% Ca( OH)2( CS + Ca + U). Moreover,CS was treated with biological treatment by inoculation of either Lentinus edodes( CS + Po) or Pleurotus ostreatus( CS + Pl) or crushing CS by adding minor ingredient processed into pellet feed,samples from all treatment were analyzed for the nutrients,In vitro dry matter digestibility( INDMD) and free gossypol detoxification rate. The second investigated was the use of crushed or granulation CS as a test feed followed by voluntary feed intake and preference test with sheep. CS + Ca + U treatment can reach up the CP and IVDMD to 9% and 36%,respectively. CS + Po decreased the fiber component and improved CP content and IVDMD. The free gossypol content declined and the free gossypol detoxification rate reached more than 50%. By feeding sheep under the same level of concentrate and corn silage,the voluntary feed intake and daily weight gain in granulation group is higher than in crushing group( P < 0. 05). Crushing CS by adding minor ingredient processed into a pellet feed was best in terms of improved nutritional quality,feed intake and preference,and it was safe and practical method that can be widely used in sheep production systems,to promote the CS feed utilization in similar areas.展开更多
A sustainable process was explored for the preparation of 5-hydroxymethylfurfural(HMF) by catalytic degradation of the waste cotton stalk. Solid super-acid(SO_4^(2-)/ZrO_2) was used as an efficient catalyst for the de...A sustainable process was explored for the preparation of 5-hydroxymethylfurfural(HMF) by catalytic degradation of the waste cotton stalk. Solid super-acid(SO_4^(2-)/ZrO_2) was used as an efficient catalyst for the degradation of cotton stalk. Both decomposition experiments and kinetic study were conducted for the exploration of degradation condition and kinetics mechanism. The optimized experimental conditions are reaction temperature 503 K, reaction time 75 min and dosage of catalyst 30%(mass fraction) based on the decomposition experiments, under which a maximum yield of 27.2% for HMF could be achieved. Kinetic study was then carried out in the presence of SO_4^(2-)/ZrO_2. The theoretical results indicate that the activation energies for reducing sugar and HMF with catalyst are 96.71 k J/mol, 84.21 kJ/mol in the presence of SO_4^(2-)/ZrO_2, and they are 105.96 k J/mol and 119.37 k J/mol in the absence of SO_4^(2-)/ZrO_2.展开更多
The combustion kinetics of biomass-cotton stalk (CS), polymer-polypro-pylene (PP) and blend of polymer/biomass-polypropylene/cotton stalk blends were examined through thermo gravimetric analysis in this study. The exp...The combustion kinetics of biomass-cotton stalk (CS), polymer-polypro-pylene (PP) and blend of polymer/biomass-polypropylene/cotton stalk blends were examined through thermo gravimetric analysis in this study. The experiments were performed under non-isothermal conditions in the 298 - 873 K temperature interval. The heating rate of this research realized under the air atmosphere was designated as 5 K·min-1. The particle size effect on the combustion behavior of cotton stalk was also studied. A decrease in the maximum rate of decomposition and an increase in the temperature of maximum decomposition with increasing particle size were obtained. Three different models based on the Arrhenius method were used to analyze differential thermo gravimetric data. Blending ratio effects of biomass-cotton stalk and polymer-polypropylene on the combustion kinetics were further explored. Additionally, factors and kinetic parameters were also discussed. Activation energies obtained through the Arrhenius method (n = 1) were much lower than that of polypropylene for all blends. As a result of the research, as the weight percentage of polypropylene in the mixture rises, an increase in activation energy values was observed. The minimum value of the activation energy was calculated with PP/CS with 2/3 blending ratio as 35.8 kJ·mol-1.展开更多
During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials w...During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials was devised to lower the breaking rate.The cotton stalk pulling component was made up of rollers and flexible belts that pull the stalks using clamping force and the forward speed of the tractor.The influence of various factors in the equipment on the harvesting effect of cotton stalks were analyzed through response surface experiments,and a multiple quadratic regression response surface model with missing pulling rate and breakage rate as response values was established.The significant of influencing factors on the breaking rate of cotton stalks are in a descending order as:the angle of cotton stalk pulling,tractor’s forward speed,and the clamping speed of the cotton stalk component.The working parameters of the wheel-belt type cotton stalk pulling machine have been optimized using the response surface combination experimental method,and the optimal parameter combination was obtained as:tractor forward speed of 4.5 km/h,cotton stalk pulling angle of 60°,and clamping speed of the cotton stalk pulling component of 349 r/min.The results of validation experiments showed that the missing pulling rate of cotton stalks was 5.06%and the breakage rate was 13.12%,indicating a good harvesting effect of the cotton stalks.The model was reasonable and the performance parameters could meet the relevant inspection requirements.The results can provide a reference for further research on the technology of flexible cotton stalk pulling.展开更多
In Xinjiang,in the process of whole stalk harvesting of cotton stalks,there is a problem that the cotton stalks are easily pulled off,and there is an urgent need to develop flexible stalk-pulling machines.Through lite...In Xinjiang,in the process of whole stalk harvesting of cotton stalks,there is a problem that the cotton stalks are easily pulled off,and there is an urgent need to develop flexible stalk-pulling machines.Through literature,patent summary,and field research,it is found that domestic researchers have designed many kinds of machines for the problem of easy breaking of cotton stalks,but there is no flexible cotton stalk-pulling machine for the time being.In this study,two flexible cotton stalk-pulling machines were intended to address the problem of easy breakage of cotton stalks.On the basis of the first-generation machine,the design of the second-generation machine was improved.In order to further improve the operational performance of the flexible cotton stalks pulling tools,the operational mechanism of the core working parts of the tools was analyzed and a comparative test was done in a large field.Analysis and the comparative tests proved that improving the clamping working stroke s of the stalk-pulling components can effectively reduce the cotton stalks leakage rate.By using a flexible clamping process,a part of the deformation of cotton stalks can be transferred to the flexible material.To a certain extent,the deformation length L of the contact surface between the cotton stalk and the stalk pulling part is reduced,and the deformation displacementΔy is correspondingly lower.The toughness of the cotton stalk is not significantly decreased and the cotton stalk does not break easily.The improved second-generation machine has a 3.67% to 3.79% lower cotton stalks leakage rate and a 5.65% to 6.30% lower cotton stalks breakage rate than the first-generation machine.As the land in Xinjiang is clay soil,soil bonding to cotton stalks pulling force F2 is larger,resulting in cotton stalks being more difficult to be pulled out of the machine at once.The test proved that the improved second-generation implements had a significant improvement in the cotton stalk-pulling effect because of the subsequent pulling interval CD.The test results verify the analysis results and the research results can provide a theoretical basis for the subsequent structural improvement and performance enhancement of the flexible cotton stalk-pulling machine,which is of reference significance for solving the problem that the cotton stalks are easily pulled and broken in Xinjiang,China.展开更多
The restitution coefficient(RC)of cotton stalks is an important elementary physical parameter that is required to establish the crushing mechanical model and research the film residue separation machinery.In this stud...The restitution coefficient(RC)of cotton stalks is an important elementary physical parameter that is required to establish the crushing mechanical model and research the film residue separation machinery.In this study,the calculation method of restitution coefficient considering the rotation motion of stalk-shaped agricultural materials was derived based on the principle of kinematics and the energy restitution coefficient method,and a test bench for measuring the RC was designed and built.The effects of collision material,moisture content,length,diameter,release height,and collision angle respectively on the RC were investigated by single-factor experiments and orthogonal experiments,and the regression models between influence factors and the RC were established.The results showed that Q235 showed the highest value of the RC,and it was followed by cotton stalks and soil lumps,sequentially.The RC of cotton stalks decreased with the increase of moisture content and diameter,while it increased at first and then decreased with the increase of length.As the release height was less than 500 mm,the RC increased with the increased release height.As the collision angle was less than 40°,the RC showed a linear increasing trend.The significance of the effects of factors on RC decreased with the following sequence:collision angle,length,release height,diameter,and moisture content.Length,collision angle,and release height were extremely significant.The contrast test results showed that the values based on Newton’s restitution coefficient method were smaller than that based on the energy restitution coefficient method.The verification test showed that the predicted rebound height of cotton stalks calculated based on the energy restitution coefficient method was closer to the actual rebound height,and the relative error was less than 5%.展开更多
Cotton stalks(CS)are lignocellulosic agricultural by-products,a potential source for biogas production,but pretreatment must be considered since hydrolysis is the rate-limiting stage for lignocellulosic biomass substr...Cotton stalks(CS)are lignocellulosic agricultural by-products,a potential source for biogas production,but pretreatment must be considered since hydrolysis is the rate-limiting stage for lignocellulosic biomass substrates.This study investigates the feasibility of mechanical pretreatment of CS to enhance methane production.Batch anaerobic digestion of CS samples with particle sizes ranging from 0.5 to 65 mm was carried out in 1 L eudiometer batch digesters for 48 days at 37◦C.Results showed that methane yield was inversely proportional to particle size,and the quality of biogas was good(54.0-55.2%CH_(4)).Significant increases in methane yield were observed with 20.3%and 26%for samples with a particle size of 3 mm and 0.5 mm,respectively,compared to untreated CS.The coefficient of anaerobic energy turnover was relatively low(20.2-25.5%).Reduction of the CS particle size to 3 mm or less is recommended to achieve effective methane conversion and decrease the retention time in an anaerobic digester from 31 to about 25 days.However,to offset the high energy demand required for grinding,further research should be conducted in combining size reduction with chemical and physicochemical pretreatment.展开更多
Drying characteristics,energy consumption and drying kinetics modeling of crashed cotton stalks dried in a microwave dryer were investigated in this research.A microwave dryer with an output power of 1000 W and 2450 M...Drying characteristics,energy consumption and drying kinetics modeling of crashed cotton stalks dried in a microwave dryer were investigated in this research.A microwave dryer with an output power of 1000 W and 2450 MHz was employed,and the effects of material load ranging from 50 g to 250 g on drying time,drying rate,drying efficiency and specific energy consumption were evaluated.The results showed that drying rate decreased with drying duration.A rising rate period was followed by a falling rate period and the overall drying process occurred in the falling rate period.Six mathematical models were used to fit the drying rates data of crashed cotton stalks,and Midilli et al.model was found the best prediction model by comparing R2,RMSE andχ^(2)values between experimental and predicted moisture ratios.With decrease in material load from 250 g to 50 g,effective moisture diffusivity increased from 2.8668×10^(-8)m^(2)/s to 7.9817×10^(-8)m^(2)/s.Results also indicated that drying efficiency and specific energy consumption significantly increased with the increase of the material load.Average drying efficiency and specific energy consumption varied in the range of 7.52%-19.78%and 12.49-35.90 MJ/kg water,respectively.There were a lowest energy consumption of 10.99 MJ/kg water and a highest drying efficiency of 17.13%at the material load level of 250 g.展开更多
Sewage sludge produced by municipal sewage treatment plants can potentially be used as a biomass energy source because of its high organic content.Presently,the conversion and utilization of rapidly growing amounts of...Sewage sludge produced by municipal sewage treatment plants can potentially be used as a biomass energy source because of its high organic content.Presently,the conversion and utilization of rapidly growing amounts of sewage sludge represent an urgent challenge in China.Thermal conversion of sewage sludge to biochar through pyrolysis is a promising solution to this problem.However,biochar produced by pyrolysis of sewage sludge alone has a poor pore structure as a result of its low C content and high ash content.Furthermore,it is enriched in heavy metals that may pose high ecological risks.In this study,we addressed these issues through co-pyrolysis of sewage sludge and cotton stalks(1:1,wt./wt.)at different pyrolysis temperatures ranging from 350℃ to 750℃.The properties and surface characteristics of the biochars were investigated.Meanwhile,the transformation behavior of heavy metals during the co-pyrolysis process was studied,and the potential ecological risks of heavy metals in biochars were assessed.The results showed that elevated pyrolysis temperatures reduced the biochar yield and C content of the biochars,whereas such temperatures increased the pH value and ash content of the biochars.The biochars prepared at different pyrolysis temperatures were all mesoporous materials.The elevated temperatures promoted the transformation of heavy metals from mobile fractions to stable ones,thus resulting in a significant decrease in the ecological risks.In summary,co-pyrolysis of sewage sludge with cotton stalks proved to be a feasible method for the conversion and utilization of sewage sludge.展开更多
The chemical composition and thermal properties of natural fibers are the most critical variables that determine the overall properties of the fibers and influence their processing and use in different sustainable app...The chemical composition and thermal properties of natural fibers are the most critical variables that determine the overall properties of the fibers and influence their processing and use in different sustainable applications,such as their conversion into bioenergy and biocomposites.Their thermal and mechanical properties can be estimated by evaluating the content of cellulose,lignin,and other extractives in the fibers.In this research work,the chemical composition and thermal properties of three fibers,namely bagasse,kenaf bast fibers,and cotton stalks,were evaluated to assess their potential utilization in producing biocomposites and bioenergy materials.The chemical composition analysis followed the Technical Association of the Pulp and Paper Industry Standards(TAPPI)methods.The total phenol content was quantified using the Folin-Ciocalteu method,while Fourier Transform Infrared Spectroscopy(FTIR)was employed to assess the light absorption by the bonds.To evaluate thermal stability and higher heating values,Thermogravimetric Analysis(TGA),Differential Scanning Calorimetry(DSC),and bomb calorimetry were performed.The chemical analysis revealed that bagasse contained 50.6%cellulose and 21.6%lignin,kenaf bast fibers had 58.5%cellulose and 10%lignin,and cotton stalks exhibited 40.3%cellulose and 21.3%lignin.The FTIR curves demonstrated a notable similarity among the fibers.The TGA analysis showed degradation temperatures of 321°C for bagasse,354°C for kenaf bast fibers,and 289°C for cotton stalks.The DSC analysis revealed glass transition temperatures of 81°C for bagasse,66.3°C for cotton stalks,and 64.5°C for kenaf bast fibers.The higher heating values were measured as 17.3,16.6 and 17.1 MJ/kg for bagasse,kenaf bast fibers,and cotton stalks,respectively.The three fibers have a high potential for biocomposites and bioenergy material manufacturing.展开更多
文摘[Purpose]To research upon the structure and pyrolysis of cotton stalk.[Method] In this paper thermogravimetric analysis is adopted to study pyrolysis characteristics on the longitudinal direction of cotton stalk（the stick and the root）and on the traverse direction（the cuticle,cortex and medulla）.[Result] Cotton stalk is a material of uneven and irregular texture,and there are great differences in the structure of all these parts on the longitudinal and traverse directions,especially in the contents of different components in each layer.The reaction in the stick and root becomes violent along with the increase in the rising rate of temperature,and carbon yield rate decreases in turn.Besides with the same rising rate of temperature,carbon yield rate of cotton stick is higher than the one of cotton root.Carbon yield rates of cuticle,cortex and medulla decrease in turn while the violence of the reaction in cuticle is less severe than in cortex and medulla.[Conclusion] It has provided theoretical basis for obtaining activated carbon technology of cotton stick.
基金Supported by National Natural Science Foundation of China(31360565)
文摘Two separate experiments were carried out: the first one involved a study of the chemical and some intrinsic feed characteristics of raw cotton stalk( CS) and the efficiency of chemical,biological treatments on the improvement of the feed value of CS. CS was treated with chemical treatment by mixing 3% Ca( OH)2( CS + Ca),3% urea( CS + U),3% urea +3% Ca( OH)2( CS + Ca + U). Moreover,CS was treated with biological treatment by inoculation of either Lentinus edodes( CS + Po) or Pleurotus ostreatus( CS + Pl) or crushing CS by adding minor ingredient processed into pellet feed,samples from all treatment were analyzed for the nutrients,In vitro dry matter digestibility( INDMD) and free gossypol detoxification rate. The second investigated was the use of crushed or granulation CS as a test feed followed by voluntary feed intake and preference test with sheep. CS + Ca + U treatment can reach up the CP and IVDMD to 9% and 36%,respectively. CS + Po decreased the fiber component and improved CP content and IVDMD. The free gossypol content declined and the free gossypol detoxification rate reached more than 50%. By feeding sheep under the same level of concentrate and corn silage,the voluntary feed intake and daily weight gain in granulation group is higher than in crushing group( P < 0. 05). Crushing CS by adding minor ingredient processed into a pellet feed was best in terms of improved nutritional quality,feed intake and preference,and it was safe and practical method that can be widely used in sheep production systems,to promote the CS feed utilization in similar areas.
基金Project(2010DFA41440)supported by China-Japan International CooperationProject(2016TP1007)supported by the Hunan Provincial Science and Technology Plan,ChinaProject(21376269)supported by the National Natural Science Foundation of China
文摘A sustainable process was explored for the preparation of 5-hydroxymethylfurfural(HMF) by catalytic degradation of the waste cotton stalk. Solid super-acid(SO_4^(2-)/ZrO_2) was used as an efficient catalyst for the degradation of cotton stalk. Both decomposition experiments and kinetic study were conducted for the exploration of degradation condition and kinetics mechanism. The optimized experimental conditions are reaction temperature 503 K, reaction time 75 min and dosage of catalyst 30%(mass fraction) based on the decomposition experiments, under which a maximum yield of 27.2% for HMF could be achieved. Kinetic study was then carried out in the presence of SO_4^(2-)/ZrO_2. The theoretical results indicate that the activation energies for reducing sugar and HMF with catalyst are 96.71 k J/mol, 84.21 kJ/mol in the presence of SO_4^(2-)/ZrO_2, and they are 105.96 k J/mol and 119.37 k J/mol in the absence of SO_4^(2-)/ZrO_2.
文摘The combustion kinetics of biomass-cotton stalk (CS), polymer-polypro-pylene (PP) and blend of polymer/biomass-polypropylene/cotton stalk blends were examined through thermo gravimetric analysis in this study. The experiments were performed under non-isothermal conditions in the 298 - 873 K temperature interval. The heating rate of this research realized under the air atmosphere was designated as 5 K·min-1. The particle size effect on the combustion behavior of cotton stalk was also studied. A decrease in the maximum rate of decomposition and an increase in the temperature of maximum decomposition with increasing particle size were obtained. Three different models based on the Arrhenius method were used to analyze differential thermo gravimetric data. Blending ratio effects of biomass-cotton stalk and polymer-polypropylene on the combustion kinetics were further explored. Additionally, factors and kinetic parameters were also discussed. Activation energies obtained through the Arrhenius method (n = 1) were much lower than that of polypropylene for all blends. As a result of the research, as the weight percentage of polypropylene in the mixture rises, an increase in activation energy values was observed. The minimum value of the activation energy was calculated with PP/CS with 2/3 blending ratio as 35.8 kJ·mol-1.
基金financially supported by the National Nature Foundation Project(Grant No.52365038)the National Nature Foundation Project(Grant No.51865058)+3 种基金the Xinjiang Uygur Autonomous Region Agricultural Science and Technology Extension and Service Project(Grant No.NTFW-2022-17)the Xinjiang Uygur Autonomous Region Key R&D Project(Grant No.2022B02022-2)the Xinjiang Uygur Autonomous Region Key R&D Project(Grant No.2022B02023-3)the Xinjiang Uygur Autonomous Region Youth Science Fund(Grant No.2022D01B91).
文摘During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials was devised to lower the breaking rate.The cotton stalk pulling component was made up of rollers and flexible belts that pull the stalks using clamping force and the forward speed of the tractor.The influence of various factors in the equipment on the harvesting effect of cotton stalks were analyzed through response surface experiments,and a multiple quadratic regression response surface model with missing pulling rate and breakage rate as response values was established.The significant of influencing factors on the breaking rate of cotton stalks are in a descending order as:the angle of cotton stalk pulling,tractor’s forward speed,and the clamping speed of the cotton stalk component.The working parameters of the wheel-belt type cotton stalk pulling machine have been optimized using the response surface combination experimental method,and the optimal parameter combination was obtained as:tractor forward speed of 4.5 km/h,cotton stalk pulling angle of 60°,and clamping speed of the cotton stalk pulling component of 349 r/min.The results of validation experiments showed that the missing pulling rate of cotton stalks was 5.06%and the breakage rate was 13.12%,indicating a good harvesting effect of the cotton stalks.The model was reasonable and the performance parameters could meet the relevant inspection requirements.The results can provide a reference for further research on the technology of flexible cotton stalk pulling.
基金This work was supported by the Key R&D Project of Xinjiang Uygur Autonomous Region(Grant No.2022B02022-2)the Key R&D Project of Xinjiang Uygur Autonomous Region(Grant No.2022B02023-3)+3 种基金the Agricultural Science and Technology Promotion and Service Project of Xinjiang Uygur Autonomous Region(Grant No.NTFW-2022-17)the Tianshan Innovation Team Project of Xinjiang Uygur Autonomous Region(Grant No.2020D14037)the Natural Science Foundation of Xinjiang Uygur Autonomous Region(Grant No.2019D01A45)the National Natural Science Foundation of China(Grant No.51865058).
文摘In Xinjiang,in the process of whole stalk harvesting of cotton stalks,there is a problem that the cotton stalks are easily pulled off,and there is an urgent need to develop flexible stalk-pulling machines.Through literature,patent summary,and field research,it is found that domestic researchers have designed many kinds of machines for the problem of easy breaking of cotton stalks,but there is no flexible cotton stalk-pulling machine for the time being.In this study,two flexible cotton stalk-pulling machines were intended to address the problem of easy breakage of cotton stalks.On the basis of the first-generation machine,the design of the second-generation machine was improved.In order to further improve the operational performance of the flexible cotton stalks pulling tools,the operational mechanism of the core working parts of the tools was analyzed and a comparative test was done in a large field.Analysis and the comparative tests proved that improving the clamping working stroke s of the stalk-pulling components can effectively reduce the cotton stalks leakage rate.By using a flexible clamping process,a part of the deformation of cotton stalks can be transferred to the flexible material.To a certain extent,the deformation length L of the contact surface between the cotton stalk and the stalk pulling part is reduced,and the deformation displacementΔy is correspondingly lower.The toughness of the cotton stalk is not significantly decreased and the cotton stalk does not break easily.The improved second-generation machine has a 3.67% to 3.79% lower cotton stalks leakage rate and a 5.65% to 6.30% lower cotton stalks breakage rate than the first-generation machine.As the land in Xinjiang is clay soil,soil bonding to cotton stalks pulling force F2 is larger,resulting in cotton stalks being more difficult to be pulled out of the machine at once.The test proved that the improved second-generation implements had a significant improvement in the cotton stalk-pulling effect because of the subsequent pulling interval CD.The test results verify the analysis results and the research results can provide a theoretical basis for the subsequent structural improvement and performance enhancement of the flexible cotton stalk-pulling machine,which is of reference significance for solving the problem that the cotton stalks are easily pulled and broken in Xinjiang,China.
基金This work was financially supported by the funding of the Southern Xinjiang Key Industry Innovation and Development Support Program(Grant No.2020DB008)the Graduate Education Innovation Project of Xinjiang Uygur Autonomous Region(Grant No.XJ2022G085)+1 种基金the Open Fund of Jiangsu Province and Education Ministry Co-sponsored Synergistic Innovation Center of Modern Agricultural Equipment(Grant No.XTCX2006)the National Natural Science Foundation of China(Grant No.52065058).
文摘The restitution coefficient(RC)of cotton stalks is an important elementary physical parameter that is required to establish the crushing mechanical model and research the film residue separation machinery.In this study,the calculation method of restitution coefficient considering the rotation motion of stalk-shaped agricultural materials was derived based on the principle of kinematics and the energy restitution coefficient method,and a test bench for measuring the RC was designed and built.The effects of collision material,moisture content,length,diameter,release height,and collision angle respectively on the RC were investigated by single-factor experiments and orthogonal experiments,and the regression models between influence factors and the RC were established.The results showed that Q235 showed the highest value of the RC,and it was followed by cotton stalks and soil lumps,sequentially.The RC of cotton stalks decreased with the increase of moisture content and diameter,while it increased at first and then decreased with the increase of length.As the release height was less than 500 mm,the RC increased with the increased release height.As the collision angle was less than 40°,the RC showed a linear increasing trend.The significance of the effects of factors on RC decreased with the following sequence:collision angle,length,release height,diameter,and moisture content.Length,collision angle,and release height were extremely significant.The contrast test results showed that the values based on Newton’s restitution coefficient method were smaller than that based on the energy restitution coefficient method.The verification test showed that the predicted rebound height of cotton stalks calculated based on the energy restitution coefficient method was closer to the actual rebound height,and the relative error was less than 5%.
文摘Cotton stalks(CS)are lignocellulosic agricultural by-products,a potential source for biogas production,but pretreatment must be considered since hydrolysis is the rate-limiting stage for lignocellulosic biomass substrates.This study investigates the feasibility of mechanical pretreatment of CS to enhance methane production.Batch anaerobic digestion of CS samples with particle sizes ranging from 0.5 to 65 mm was carried out in 1 L eudiometer batch digesters for 48 days at 37◦C.Results showed that methane yield was inversely proportional to particle size,and the quality of biogas was good(54.0-55.2%CH_(4)).Significant increases in methane yield were observed with 20.3%and 26%for samples with a particle size of 3 mm and 0.5 mm,respectively,compared to untreated CS.The coefficient of anaerobic energy turnover was relatively low(20.2-25.5%).Reduction of the CS particle size to 3 mm or less is recommended to achieve effective methane conversion and decrease the retention time in an anaerobic digester from 31 to about 25 days.However,to offset the high energy demand required for grinding,further research should be conducted in combining size reduction with chemical and physicochemical pretreatment.
基金the Public Interest of Agricultural biomass characteristics and Sharing platform technology research(project number:201003063).
文摘Drying characteristics,energy consumption and drying kinetics modeling of crashed cotton stalks dried in a microwave dryer were investigated in this research.A microwave dryer with an output power of 1000 W and 2450 MHz was employed,and the effects of material load ranging from 50 g to 250 g on drying time,drying rate,drying efficiency and specific energy consumption were evaluated.The results showed that drying rate decreased with drying duration.A rising rate period was followed by a falling rate period and the overall drying process occurred in the falling rate period.Six mathematical models were used to fit the drying rates data of crashed cotton stalks,and Midilli et al.model was found the best prediction model by comparing R2,RMSE andχ^(2)values between experimental and predicted moisture ratios.With decrease in material load from 250 g to 50 g,effective moisture diffusivity increased from 2.8668×10^(-8)m^(2)/s to 7.9817×10^(-8)m^(2)/s.Results also indicated that drying efficiency and specific energy consumption significantly increased with the increase of the material load.Average drying efficiency and specific energy consumption varied in the range of 7.52%-19.78%and 12.49-35.90 MJ/kg water,respectively.There were a lowest energy consumption of 10.99 MJ/kg water and a highest drying efficiency of 17.13%at the material load level of 250 g.
基金supported by the National Key Research&Development Program of China(Grant NO.2017YFC0504400-1)the National Natural Science Foundation of China(Grants NO.51074170,51704016)
文摘Sewage sludge produced by municipal sewage treatment plants can potentially be used as a biomass energy source because of its high organic content.Presently,the conversion and utilization of rapidly growing amounts of sewage sludge represent an urgent challenge in China.Thermal conversion of sewage sludge to biochar through pyrolysis is a promising solution to this problem.However,biochar produced by pyrolysis of sewage sludge alone has a poor pore structure as a result of its low C content and high ash content.Furthermore,it is enriched in heavy metals that may pose high ecological risks.In this study,we addressed these issues through co-pyrolysis of sewage sludge and cotton stalks(1:1,wt./wt.)at different pyrolysis temperatures ranging from 350℃ to 750℃.The properties and surface characteristics of the biochars were investigated.Meanwhile,the transformation behavior of heavy metals during the co-pyrolysis process was studied,and the potential ecological risks of heavy metals in biochars were assessed.The results showed that elevated pyrolysis temperatures reduced the biochar yield and C content of the biochars,whereas such temperatures increased the pH value and ash content of the biochars.The biochars prepared at different pyrolysis temperatures were all mesoporous materials.The elevated temperatures promoted the transformation of heavy metals from mobile fractions to stable ones,thus resulting in a significant decrease in the ecological risks.In summary,co-pyrolysis of sewage sludge with cotton stalks proved to be a feasible method for the conversion and utilization of sewage sludge.
基金the Tenure Track Position“Bois:Biobased materials”part of E2S UPPA supported by the“Investissements d’Avenir”French Program managed by ANR(ANR-16-IDEX-0002).
文摘The chemical composition and thermal properties of natural fibers are the most critical variables that determine the overall properties of the fibers and influence their processing and use in different sustainable applications,such as their conversion into bioenergy and biocomposites.Their thermal and mechanical properties can be estimated by evaluating the content of cellulose,lignin,and other extractives in the fibers.In this research work,the chemical composition and thermal properties of three fibers,namely bagasse,kenaf bast fibers,and cotton stalks,were evaluated to assess their potential utilization in producing biocomposites and bioenergy materials.The chemical composition analysis followed the Technical Association of the Pulp and Paper Industry Standards(TAPPI)methods.The total phenol content was quantified using the Folin-Ciocalteu method,while Fourier Transform Infrared Spectroscopy(FTIR)was employed to assess the light absorption by the bonds.To evaluate thermal stability and higher heating values,Thermogravimetric Analysis(TGA),Differential Scanning Calorimetry(DSC),and bomb calorimetry were performed.The chemical analysis revealed that bagasse contained 50.6%cellulose and 21.6%lignin,kenaf bast fibers had 58.5%cellulose and 10%lignin,and cotton stalks exhibited 40.3%cellulose and 21.3%lignin.The FTIR curves demonstrated a notable similarity among the fibers.The TGA analysis showed degradation temperatures of 321°C for bagasse,354°C for kenaf bast fibers,and 289°C for cotton stalks.The DSC analysis revealed glass transition temperatures of 81°C for bagasse,66.3°C for cotton stalks,and 64.5°C for kenaf bast fibers.The higher heating values were measured as 17.3,16.6 and 17.1 MJ/kg for bagasse,kenaf bast fibers,and cotton stalks,respectively.The three fibers have a high potential for biocomposites and bioenergy material manufacturing.
