By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolys...By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolysis zone of downdraft gasifier. The simulation results in inert atmosphere and pyrolysis zone agree well with the published experimental results. The pyrolysis of biomass pellets in pyrolysis zone is investigated, and the results show that the estimated convective heat transfer coefficient and emissivity coefficient are suitable. The mean pyrolysis time is 15.22%, shorter than that in inert atmosphere, and the pellet pyrolysis process in pyrolysis zone belongs to fast pyrolysis. Among the pyrolysis products, tar yield is the most, gas the second, and char the least. During pyrolysis, the temperature change near the center is contrary to that near the surface. Pyrolysis gradually moves inwards layer by layer. With the increase of pyrolysis temperature and pellet diameter, the total pyrolysis time, tar yield, char yield and gas yield change in different ways. The height of pyrolysis zone is calculated to be 1.51—3.51 times of the characteristic pellet diameter.展开更多
The use of biomass is increasing because it is a form of renewable energy that provides high heating value.Rapid measurements could be used to check the quality of biomass pellets during production.This research aims ...The use of biomass is increasing because it is a form of renewable energy that provides high heating value.Rapid measurements could be used to check the quality of biomass pellets during production.This research aims to apply a near-infrared(NIR)hyperspectral imaging system for the evaluation of the true density of individual biomass pellets during the production process.Real-time measurement of the true density could be beneficial for the operation settings,such as the ratio of the binding agent to the raw material,the temperature of operation,the production rate,and the mixing ratio.The true density could also be used for rough measurement of the bulk density,which is a necessary parameter in commercial production.Therefore,knowledge of the true density is required during production in order to maintain the pellet quality as well as operation conditions.A prediction model was developed using partial least squares(PLS)regression across different wavelengths selected using different spectral pre-treatment methods and variable selection methods.After model development,the performance of the models was compared.The best model for predicting the true density of individual pellets was developed with first-derivative spectra(D1)and variables selected by the genetic algorithm(GA)method,and the number of variables was reduced from 256 to 53 wavelengths.The model gave R_(cal)^(2),R_(val)^(2),SEC,SEP,and RPD values of 0.88,0.89,0.08 g/cm^(3),0.07 g/cm^(3),and 3.04,respectively.The optimal prediction model was applied to construct distribution maps of the true density of individual biomass pellets,with the level of the predicted values displayed in colour bars.This imaging technique could be used to check visually the true density of biomass pellets during the production process for warnings to quality control equipment.展开更多
Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the cor...Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the corresponding flocculating efficiency. The atomic force microscope ( AFM) images of mycelial surface indicate that the mycelia pellet can immobilize bioflocculant-producing bacteria F2 and F6 as a biomass carrier. The flocculating efficiency of bioflocculant produced by this combined organism was studied under the optimum flocculating conditions obtained by Response Surface Methodology ( RSM ) . The fermentation yield of the combined mycelial pellet is about 2. 6 g / L,which is higher than that of the free bacteria ( only 2. 2 g / L) . Flocculating efficiency of the combined mycelial pellet was comparable with that of bioflocculant generated by the free bacteria. The bioflocculant yield is enhanced and the flocculating efficiency of the co-culture is uninfluenced after immobilized with mycelial pellet as a carrier. In conclusion,the mycelial pellet is feasible as a biomass carrier for the immobilization of bioflocculant-producing bacteria.展开更多
A disruptive approach to a fundamental process has been applied in a biomass combustion device with two variable speed fans to supply air for gasification and another for combustion processes,separately.Besides,the pr...A disruptive approach to a fundamental process has been applied in a biomass combustion device with two variable speed fans to supply air for gasification and another for combustion processes,separately.Besides,the preheating of secondary air,required for combustion process was also ensured through annulus chamber before being fed into the combustion chamber.The turbulent flow and homogenous mixing were also ensured by controlling the flow rate resulting in the reduced emissions of carbon monoxide(CO)and fine particulate matter(PM 2.5,particulate matter having aerodynamic diameter<2.5 micron).The design approach applied here has also ensured the homogeneous mixing of preheated air with the volatiles,resulted in cleaner combustion.This arrangement has led to the emissions of PM2.5 and CO much better than those of the earlier cookstove models,and very close to that of a liquefied petroleum gas(LPG)stove.Further,the comparative analysis based on the modified star rating of total 15(14 are biomass and another LPG)cookstove models tested using the same standard methodology has been done and presented in this study.Based on the star rating,the performance of the LPG stove was found to be best and assigned as a 5-star product followed by the IITD model(4-star),while the other 13 models got different ratings starting from 1-star to 3-star,respectively.Also,the thermal performance of the IITD cookstove model is found to be the highest,while the emission characteristics are found to be the least among all biomass cookstove models,presented here.展开更多
Biomass is a renewable, economic and readily available resource of energy that has potential to substitute fossil fuels in many applications such as heat, electricity and biofuels. The increased use of the agricultura...Biomass is a renewable, economic and readily available resource of energy that has potential to substitute fossil fuels in many applications such as heat, electricity and biofuels. The increased use of the agricultural biomass can help the agricultural based societies in achieving energy security and creating employment without causing environmental degradation. However, the viability and feasibility of electricity generation from agricultural biomass depends upon the availability of biomass supply at a competitive cost. The present study investigates the availability of agricultural biomass for distributed power generation in Greece (Kozani). The study concludes with a discussion on significance and challenges of decentralized electricity generation for rural energy supply, including brief description about economical, social, environmental and technical aspects of bioelectricity. With the application of the life cycle analysis applied, the environmental and economic impacts that will occur in the region of Kozani in Greece, where a biomass wood pellets production workshop is operating, have been assessed. The total annual emission of CO 657.9 gr, HC 22.36 gr, PM 67.94 and NOx 8.832,2 gr was calculated. The economic evaluation estimated the payback period for the investment in this plant to be approximately 3 years.展开更多
In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG ...In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG at different heating rates were revealed by the thermogravimetric method and differential thermogravimetric method.The ignition temperature,burnout temperature,and maximum weight loss rate were measured,and the comprehensive combustion and flammability indexes were calculated.The results showed that the composite combustion characteristic index and flammability index increased with the increase in heating rate.The addition of PE and CG additives could effectively extend the combustion time.The Coats-Redfern(C-R)reaction model and N-order reaction model were used to evaluate the kinetic parameters of the blends.The results showed that 12.5%PE+12.5%CG particles had the lowest activation energy(Ea=103.73 kJ·mol^(-1))at the volatile combustion stage.The dynamics conform to the third-order dynamics model.In addition,the applicability of C-R model,Flynn-Wall-Ozawa(FWO)model,and Starink model in the calculation of activation energy was explored,and it was found that the FWO model is not suitable for the calculation of activation energy of biomass pellet combustion kinetics.This study provides a new method for the development and utilization of mixed fuel particles of cotton stalk and solid waste and expands the application prospect of biomass.展开更多
文摘By coupling the heat transfer equation with semi-global chemical reaction kinetic equations, a onedimensional, unsteady mathematical model is developed to describe the pyrolysis of single biomass pellet in the pyrolysis zone of downdraft gasifier. The simulation results in inert atmosphere and pyrolysis zone agree well with the published experimental results. The pyrolysis of biomass pellets in pyrolysis zone is investigated, and the results show that the estimated convective heat transfer coefficient and emissivity coefficient are suitable. The mean pyrolysis time is 15.22%, shorter than that in inert atmosphere, and the pellet pyrolysis process in pyrolysis zone belongs to fast pyrolysis. Among the pyrolysis products, tar yield is the most, gas the second, and char the least. During pyrolysis, the temperature change near the center is contrary to that near the surface. Pyrolysis gradually moves inwards layer by layer. With the increase of pyrolysis temperature and pellet diameter, the total pyrolysis time, tar yield, char yield and gas yield change in different ways. The height of pyrolysis zone is calculated to be 1.51—3.51 times of the characteristic pellet diameter.
基金supported by Research and Graduate Studies,Khon Kaen University,Khon Kaen,Thailand.
文摘The use of biomass is increasing because it is a form of renewable energy that provides high heating value.Rapid measurements could be used to check the quality of biomass pellets during production.This research aims to apply a near-infrared(NIR)hyperspectral imaging system for the evaluation of the true density of individual biomass pellets during the production process.Real-time measurement of the true density could be beneficial for the operation settings,such as the ratio of the binding agent to the raw material,the temperature of operation,the production rate,and the mixing ratio.The true density could also be used for rough measurement of the bulk density,which is a necessary parameter in commercial production.Therefore,knowledge of the true density is required during production in order to maintain the pellet quality as well as operation conditions.A prediction model was developed using partial least squares(PLS)regression across different wavelengths selected using different spectral pre-treatment methods and variable selection methods.After model development,the performance of the models was compared.The best model for predicting the true density of individual pellets was developed with first-derivative spectra(D1)and variables selected by the genetic algorithm(GA)method,and the number of variables was reduced from 256 to 53 wavelengths.The model gave R_(cal)^(2),R_(val)^(2),SEC,SEP,and RPD values of 0.88,0.89,0.08 g/cm^(3),0.07 g/cm^(3),and 3.04,respectively.The optimal prediction model was applied to construct distribution maps of the true density of individual biomass pellets,with the level of the predicted values displayed in colour bars.This imaging technique could be used to check visually the true density of biomass pellets during the production process for warnings to quality control equipment.
基金Sponsored by the National Hi-Tech Research and Development Program (Grant No. 2009AA062906)the National Creative Research Group from the National Natural Science Foundation of China (Grant No. 51121062)+1 种基金the State Key Lab of Urban Water Resource and Environment,Harbin Institute of Technology (Grant No. 2010DX09,2010TX03)the Science and Technology Development Program of Jilin Province (Grant No. 201101108)
文摘Bioflocculant-producing bacteria Agrobacterium tumefaciens F2 and Bacillus sphaeicus F6 were immobilized onto mycelial pellets to investigate the bioflocculant-producing potential of this combined organism and the corresponding flocculating efficiency. The atomic force microscope ( AFM) images of mycelial surface indicate that the mycelia pellet can immobilize bioflocculant-producing bacteria F2 and F6 as a biomass carrier. The flocculating efficiency of bioflocculant produced by this combined organism was studied under the optimum flocculating conditions obtained by Response Surface Methodology ( RSM ) . The fermentation yield of the combined mycelial pellet is about 2. 6 g / L,which is higher than that of the free bacteria ( only 2. 2 g / L) . Flocculating efficiency of the combined mycelial pellet was comparable with that of bioflocculant generated by the free bacteria. The bioflocculant yield is enhanced and the flocculating efficiency of the co-culture is uninfluenced after immobilized with mycelial pellet as a carrier. In conclusion,the mycelial pellet is feasible as a biomass carrier for the immobilization of bioflocculant-producing bacteria.
基金financial assistance provided by IIT Delhi under new faculty start-up grant for establishing the testing facilities at the laboratory in the Department of Energy Science and Engineering.
文摘A disruptive approach to a fundamental process has been applied in a biomass combustion device with two variable speed fans to supply air for gasification and another for combustion processes,separately.Besides,the preheating of secondary air,required for combustion process was also ensured through annulus chamber before being fed into the combustion chamber.The turbulent flow and homogenous mixing were also ensured by controlling the flow rate resulting in the reduced emissions of carbon monoxide(CO)and fine particulate matter(PM 2.5,particulate matter having aerodynamic diameter<2.5 micron).The design approach applied here has also ensured the homogeneous mixing of preheated air with the volatiles,resulted in cleaner combustion.This arrangement has led to the emissions of PM2.5 and CO much better than those of the earlier cookstove models,and very close to that of a liquefied petroleum gas(LPG)stove.Further,the comparative analysis based on the modified star rating of total 15(14 are biomass and another LPG)cookstove models tested using the same standard methodology has been done and presented in this study.Based on the star rating,the performance of the LPG stove was found to be best and assigned as a 5-star product followed by the IITD model(4-star),while the other 13 models got different ratings starting from 1-star to 3-star,respectively.Also,the thermal performance of the IITD cookstove model is found to be the highest,while the emission characteristics are found to be the least among all biomass cookstove models,presented here.
文摘Biomass is a renewable, economic and readily available resource of energy that has potential to substitute fossil fuels in many applications such as heat, electricity and biofuels. The increased use of the agricultural biomass can help the agricultural based societies in achieving energy security and creating employment without causing environmental degradation. However, the viability and feasibility of electricity generation from agricultural biomass depends upon the availability of biomass supply at a competitive cost. The present study investigates the availability of agricultural biomass for distributed power generation in Greece (Kozani). The study concludes with a discussion on significance and challenges of decentralized electricity generation for rural energy supply, including brief description about economical, social, environmental and technical aspects of bioelectricity. With the application of the life cycle analysis applied, the environmental and economic impacts that will occur in the region of Kozani in Greece, where a biomass wood pellets production workshop is operating, have been assessed. The total annual emission of CO 657.9 gr, HC 22.36 gr, PM 67.94 and NOx 8.832,2 gr was calculated. The economic evaluation estimated the payback period for the investment in this plant to be approximately 3 years.
基金supported by the Scientific and Technological Innovation Leading Talents of Shihezi University(Grant No.CZ002703)Science and Technology Innovation Talents Program of Shihezi University(Grant No.ZG010603)+1 种基金Backbone Technical Innovation Talents of Enterprises(Grant No.2023CB014)Science and Technology Planning Project(Grant No.2023AB032).
文摘In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG at different heating rates were revealed by the thermogravimetric method and differential thermogravimetric method.The ignition temperature,burnout temperature,and maximum weight loss rate were measured,and the comprehensive combustion and flammability indexes were calculated.The results showed that the composite combustion characteristic index and flammability index increased with the increase in heating rate.The addition of PE and CG additives could effectively extend the combustion time.The Coats-Redfern(C-R)reaction model and N-order reaction model were used to evaluate the kinetic parameters of the blends.The results showed that 12.5%PE+12.5%CG particles had the lowest activation energy(Ea=103.73 kJ·mol^(-1))at the volatile combustion stage.The dynamics conform to the third-order dynamics model.In addition,the applicability of C-R model,Flynn-Wall-Ozawa(FWO)model,and Starink model in the calculation of activation energy was explored,and it was found that the FWO model is not suitable for the calculation of activation energy of biomass pellet combustion kinetics.This study provides a new method for the development and utilization of mixed fuel particles of cotton stalk and solid waste and expands the application prospect of biomass.
