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02206 Pyrolysis of two agricultural residues: Olive and grape bagasse. Influence of particle size and temperature
07
hardwoods on a laboratory scale. It is likely a pelletized coal product using lignin waste derived from the wood hydrolysis stage of the Et alcohol conversion process will also be able to be made in the future.
IISc-DASAG biomass gasifiers: development, tech98io2200 nology, experience and economicsShara. H. N. et al. Dev. Thermochemical Biomass Cowers., 1997, 2, 10581072. ‘Edited by Bridgwater, A. V. and Boocock, D. G. B., Blackie, London, UK. The R&D team at the Combustion, Gasification and Propulsion Laboratory (CGPL) of the Indian Institute of Science, Bangalore, developed open top gasifier’technology, which was used successfully to run irrigation pumping sets, replacing diesel oil by producer gas. The technology was developed further for power generation, also with promising results. The paper describes the gasifier and presents details of its performance both in the laboratory and in the field, including experience of a plant running in an Indian village, results of tests carried out jointly by Indo-Swiss teams in Bangalore and the results of the initial operation of a plant in Chatel-StDenis, Switzerland. Details of a commercial 80 kWe cogeneration plant supplying electricity and process heat for drying to a hand-made paper factory have also been presented. The paper gives details of steps taken to commercialize the technology and puts forward the concept of Independent Rural Power Producers (IRPPs) for setting up decentralized power stations in villages. Data on the cost of power generation in biomass based IRPPs are given and the economics of electricity supplied from such decentralized plants is compared with those of coal based electricity supplied by the Indian power grid.
Alternative
energy sources (bioconversion
energy)
pyrolysis rates of any plant species might be predicted in terms of the pyrolytic characteristics of their cellulose, hemicellulose and lignin components. gal02205 Power production based on biofuels Nielson, L. and Nielsen, C. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., Znd, 1995, 533-542.
A poster presenting the Danish Biomass Programme and displaying ELSAM incentives to burn biofuels in power plants and activities to that end. ELSAM is one of the two power pools dividing Denmark into east and west. Due to government demands. ELSAM has to burn aooroximatelv 600,000 tonnes-of straw and 100,000 tonnes of wood chips by the year 2006, equivalent to approximately 10 PJ or 8% of ELSAM’s power production. To aihieve the national carbon dioxide goal of a 20% reduction by the year 2005, ELSAM plans to utilize biofuels to the equivalent of approximately 25 PJ or 15% of its power production. The company has the following goals for carbon dioxide reduction: (1) identification of suitable biofuels (e.g. straw, miscanthus, wood chips), (2) co-firing of coal and straw in 150-250 MW pulverized fuel units, (3) commercialization of loo-250 MW 50-100% biofuel-fired power plants, (3) increased efficiency on coal-fired plants through ultra super critical cycle, (4) gasification of biofuels and coal, and (5) natural gas firing in existing or new units. Information about the 9th European Bioenergy Conference, in Copenhagen on 24-28 June, 1996, is also given.
Pyrolysis of two agricultural residues: olive and grape bagasse. Influence of particle size and temperature
98lO2206
Influence of calcinatlon and reduction conditions 98/02201 on the catalyst performance in the pyrolysis process of biomass Garcia, L. et al. Energy Fuels, 1998, 12, (1) 139-143. Several preparation parameters were investigated for their effect on the performance of a co-precipitated nickel alumina catalyst for use in the pyrolysis of lignocellulosic residues. The variables considered were calcination temperature, reduction time and hydrogen flow in the reduction step. The catalyst performance was evaluated on a bench scale plant eouiooed with a continuous fluidized bed reactor usina the Waterloo fast p&!&is process (WFPP) technology. Pine sawdust wasised as the biomass and the reaction temperature was 650°C. The results show that more severe operating conditions-on the reduction process must also be applied, with higher calcination temperature, but catalyst sintering can appear when very severe reduction conditions are used.
Maximising the production of fuelwood in different silvlcultural systems
gal02202
Gambore. C. Biomass and Bioenerw. 1997. 13. (l/2). 75-81. DifferenT’ways of increasing the pro&ction’of whole-tree chips for energy production are addressed. The influence of selected silvicultural factors, such as tree species, thinning programme and especially plant density and the quality of nurse trees on the production of wood chips are examined. Calculations based on Danish vield tables and results from exoeriments on plant density and thinning grade in Denmark show an increase of 30-40% in chip harvest when the plant density is increased from an average of 4500 tree species, such as common to 6560 plants haa’. Using light-demanding alder or hybrid larch as a nurse tree in Norway spruce or beech stands can substantially increase the whole-tree chip yield if the nurse trees are chipped in the early thinnings. It is stressed that the production of wholetree chips should not jeopardise the general forest management objectives.
Modelling biomass pyrolysis in combustion 90102203 Chen, Y. et al. Chemical Physical Processes Combust., 1997, 147-150. Successful modification of the FG-DVC coal pyrolysis model means it can now be applied to biomass. Preliminary results show that it is possible to model the pyrolysis behaviour of different biomass feedstocks using kinetic parameters and product yields approximated by selected standards based on the comparison of the feedstock elemental composition. Phenomenological models of cellulose pyrolysis 98102204 Green, A. B. S. et al. Biomass and Bioenew, 1997, 13, (l/2), 15-24. An approximate total gaseous yield function- Y(t,T) was established using yields vs residence time and temperature from 50 to 1000 ms and 650900°C measured with the ultra pyrolysis system at the University of Western Ontario (UWO). With UWO data, approximate correlations were also established between individual gaseous yields and the total gaseous yield that could be used to give Y(t,T) for individual gases. Y(t,T) was extended further using shock tube pyrolysis measurements from 0.3 to 2 ms and 900 to 2100°C made at Kansas State University (KSU). In doing so, a global decay model has been developed giving analytical time and temperature dependencies for cellulose, activated cellulose, tar, prompt total gas and late total gas. Next, the impact of heating rates and heat transfer upon pyrolysis of cellulose using slow pyrolysis data obtained by thermogravimetric analysis at the Colorado School of Mines (CSM). In this effort, an accurate general relationship for Boltzmann integrals is first developed. Then, using an analytically convenient Arrhenius reaction rate (ARR) data taken at varying heating rates and with three Biot numbers was examined. Some phenomenological analytical relationships giving ARR parameter dependencies on heating rate and particle size that-appear indicative of heat transfer impacts. If adequate data becomes available these relationships might be applied to hemicellulose and lignin. Then the
Encinar, J. M. et al. Biomass and Bioenergy, 1996, 11, (5), 397-409. With the aim of determining the main characteristics of the charcoals formed and the nature and ouantitv of eases and liauids produced, the pyrolysis of olive and grape bagassd has-been studied. Temperature was varied between 300 and 900°C and particle size between 0.4 and 2 mm diameter and the experiments were carried out isothermally. Particle size does not generally exert any influence, whereas temperature is a very significant variable. Thus an increase in this variable vields an increase in thi fixed carbon content, gases produced and, to a lesser extent, ash percentage. On the other hand, volatile material and solid yields decrease with increasing temperature. The principal gases generated are Hz, CH4, CO and CO, while among the liquid components the presence of methanol, acetone, furfuryl alcohol, phenol, furfural, naphthalene and ocresol has to be highlighted. Heating values of both gas and solid phases were determined from gas composition and elemental carbon analysis. The best temperature for the pyrolysis was concluded to be between 600 and 7Oo”C, at which the production of liquids is at its maximum. Finally, a kinetic study of the pyrolysis, based on gas generation from thermal decomposition of residues, has been carried out. From this model, rate constants for the formation of each gas and their corresponding activation energies were determined. 98102207
Rheological studies on a slurry biofuel to aid in evaluating its suitability as a fuel
Natarajan, V. P. and Suppes, G. J. Fuel, 1997, 76, (14/15), 1527-1535. As biomass is an often abundant, renewable, low ash and low sulfur fuel, biofuels are promising alternatives for traditional petroleum-based fuel applications; however, traditional biofuels for internal combustion engines are not cost comoetitive with gasoline. diesel or fuel oils. One method to reduce the cost oi biofuels is to use slurry fuels which have a potential lower cost than liquid biofuels due to high conversion efficiencies. Slurry biofuels, such as a mixture of corn and water, could provide a biofuel alternative for diesel engines pressurized gasifiers and heating oil applications such as burners or gas turbines. Use of these biomass slurries poses important questions about their stability and suitability for practical applications in internal combustion engines and combustors. This work reports rheological data for stable corn-starch water slurries (CSWS) which used a polyacrylate acid thickener to eliminate settling of the slurry and to provide desirable shear-thinning behaviour for most of the compositions evaluated. The effect of shear rate on the viscosity of the CSWS was studied using a BOHLINcontrolled stress (CS) rheometer. The well-known Ostwald-de Waele power law and Sisko models for viscosity fit the data. The favourable shear thinning properties were observed for starch contents up to 45% starch and should aid pumping, injection and spraying. The heating values of the slurries, however, are undesirably low. 98/02208
Stabilisation of biofuel ashes for recycling to forest
soil fSS5ui,
B.-M. and Lindqvist,
0.
Biomass and Bioenergv,
1997, 13, (l/2),
For several years a Swedish research programme concerning the technical and ecological effects of wood fuel ash recycling to forest biotopes has been carried out. Within this oroeramme. a studv of the stabilization of ash bv the so-called self-harder&g r)rocess was cariied out. Based on results from chemical analysis, X-ray diffraction, FTIR spectroscopic and scanning electron microscopy analysis, the chemical reactions oc&rring in the ash materials on water addition and during solidification were identified. The stability and importance of the individual reaction products are discussed.
Fuel and Energy Abstracts
May 1998
199
hardwoods on a laboratory scale. It is likely a pelletized coal product using lignin waste derived from the wood hydrolysis stage of the Et alcohol conversion process will also be able to be made in the future.
IISc-DASAG biomass gasifiers: development, tech98io2200 nology, experience and economicsShara. H. N. et al. Dev. Thermochemical Biomass Cowers., 1997, 2, 10581072. ‘Edited by Bridgwater, A. V. and Boocock, D. G. B., Blackie, London, UK. The R&D team at the Combustion, Gasification and Propulsion Laboratory (CGPL) of the Indian Institute of Science, Bangalore, developed open top gasifier’technology, which was used successfully to run irrigation pumping sets, replacing diesel oil by producer gas. The technology was developed further for power generation, also with promising results. The paper describes the gasifier and presents details of its performance both in the laboratory and in the field, including experience of a plant running in an Indian village, results of tests carried out jointly by Indo-Swiss teams in Bangalore and the results of the initial operation of a plant in Chatel-StDenis, Switzerland. Details of a commercial 80 kWe cogeneration plant supplying electricity and process heat for drying to a hand-made paper factory have also been presented. The paper gives details of steps taken to commercialize the technology and puts forward the concept of Independent Rural Power Producers (IRPPs) for setting up decentralized power stations in villages. Data on the cost of power generation in biomass based IRPPs are given and the economics of electricity supplied from such decentralized plants is compared with those of coal based electricity supplied by the Indian power grid.
Alternative
energy sources (bioconversion
energy)
pyrolysis rates of any plant species might be predicted in terms of the pyrolytic characteristics of their cellulose, hemicellulose and lignin components. gal02205 Power production based on biofuels Nielson, L. and Nielsen, C. Proc. Biomass Conf. Am.: Energy, Environ., Agric. Ind., Znd, 1995, 533-542.
A poster presenting the Danish Biomass Programme and displaying ELSAM incentives to burn biofuels in power plants and activities to that end. ELSAM is one of the two power pools dividing Denmark into east and west. Due to government demands. ELSAM has to burn aooroximatelv 600,000 tonnes-of straw and 100,000 tonnes of wood chips by the year 2006, equivalent to approximately 10 PJ or 8% of ELSAM’s power production. To aihieve the national carbon dioxide goal of a 20% reduction by the year 2005, ELSAM plans to utilize biofuels to the equivalent of approximately 25 PJ or 15% of its power production. The company has the following goals for carbon dioxide reduction: (1) identification of suitable biofuels (e.g. straw, miscanthus, wood chips), (2) co-firing of coal and straw in 150-250 MW pulverized fuel units, (3) commercialization of loo-250 MW 50-100% biofuel-fired power plants, (3) increased efficiency on coal-fired plants through ultra super critical cycle, (4) gasification of biofuels and coal, and (5) natural gas firing in existing or new units. Information about the 9th European Bioenergy Conference, in Copenhagen on 24-28 June, 1996, is also given.
Pyrolysis of two agricultural residues: olive and grape bagasse. Influence of particle size and temperature
98lO2206
Influence of calcinatlon and reduction conditions 98/02201 on the catalyst performance in the pyrolysis process of biomass Garcia, L. et al. Energy Fuels, 1998, 12, (1) 139-143. Several preparation parameters were investigated for their effect on the performance of a co-precipitated nickel alumina catalyst for use in the pyrolysis of lignocellulosic residues. The variables considered were calcination temperature, reduction time and hydrogen flow in the reduction step. The catalyst performance was evaluated on a bench scale plant eouiooed with a continuous fluidized bed reactor usina the Waterloo fast p&!&is process (WFPP) technology. Pine sawdust wasised as the biomass and the reaction temperature was 650°C. The results show that more severe operating conditions-on the reduction process must also be applied, with higher calcination temperature, but catalyst sintering can appear when very severe reduction conditions are used.
Maximising the production of fuelwood in different silvlcultural systems
gal02202
Gambore. C. Biomass and Bioenerw. 1997. 13. (l/2). 75-81. DifferenT’ways of increasing the pro&ction’of whole-tree chips for energy production are addressed. The influence of selected silvicultural factors, such as tree species, thinning programme and especially plant density and the quality of nurse trees on the production of wood chips are examined. Calculations based on Danish vield tables and results from exoeriments on plant density and thinning grade in Denmark show an increase of 30-40% in chip harvest when the plant density is increased from an average of 4500 tree species, such as common to 6560 plants haa’. Using light-demanding alder or hybrid larch as a nurse tree in Norway spruce or beech stands can substantially increase the whole-tree chip yield if the nurse trees are chipped in the early thinnings. It is stressed that the production of wholetree chips should not jeopardise the general forest management objectives.
Modelling biomass pyrolysis in combustion 90102203 Chen, Y. et al. Chemical Physical Processes Combust., 1997, 147-150. Successful modification of the FG-DVC coal pyrolysis model means it can now be applied to biomass. Preliminary results show that it is possible to model the pyrolysis behaviour of different biomass feedstocks using kinetic parameters and product yields approximated by selected standards based on the comparison of the feedstock elemental composition. Phenomenological models of cellulose pyrolysis 98102204 Green, A. B. S. et al. Biomass and Bioenew, 1997, 13, (l/2), 15-24. An approximate total gaseous yield function- Y(t,T) was established using yields vs residence time and temperature from 50 to 1000 ms and 650900°C measured with the ultra pyrolysis system at the University of Western Ontario (UWO). With UWO data, approximate correlations were also established between individual gaseous yields and the total gaseous yield that could be used to give Y(t,T) for individual gases. Y(t,T) was extended further using shock tube pyrolysis measurements from 0.3 to 2 ms and 900 to 2100°C made at Kansas State University (KSU). In doing so, a global decay model has been developed giving analytical time and temperature dependencies for cellulose, activated cellulose, tar, prompt total gas and late total gas. Next, the impact of heating rates and heat transfer upon pyrolysis of cellulose using slow pyrolysis data obtained by thermogravimetric analysis at the Colorado School of Mines (CSM). In this effort, an accurate general relationship for Boltzmann integrals is first developed. Then, using an analytically convenient Arrhenius reaction rate (ARR) data taken at varying heating rates and with three Biot numbers was examined. Some phenomenological analytical relationships giving ARR parameter dependencies on heating rate and particle size that-appear indicative of heat transfer impacts. If adequate data becomes available these relationships might be applied to hemicellulose and lignin. Then the
Encinar, J. M. et al. Biomass and Bioenergy, 1996, 11, (5), 397-409. With the aim of determining the main characteristics of the charcoals formed and the nature and ouantitv of eases and liauids produced, the pyrolysis of olive and grape bagassd has-been studied. Temperature was varied between 300 and 900°C and particle size between 0.4 and 2 mm diameter and the experiments were carried out isothermally. Particle size does not generally exert any influence, whereas temperature is a very significant variable. Thus an increase in this variable vields an increase in thi fixed carbon content, gases produced and, to a lesser extent, ash percentage. On the other hand, volatile material and solid yields decrease with increasing temperature. The principal gases generated are Hz, CH4, CO and CO, while among the liquid components the presence of methanol, acetone, furfuryl alcohol, phenol, furfural, naphthalene and ocresol has to be highlighted. Heating values of both gas and solid phases were determined from gas composition and elemental carbon analysis. The best temperature for the pyrolysis was concluded to be between 600 and 7Oo”C, at which the production of liquids is at its maximum. Finally, a kinetic study of the pyrolysis, based on gas generation from thermal decomposition of residues, has been carried out. From this model, rate constants for the formation of each gas and their corresponding activation energies were determined. 98102207
Rheological studies on a slurry biofuel to aid in evaluating its suitability as a fuel
Natarajan, V. P. and Suppes, G. J. Fuel, 1997, 76, (14/15), 1527-1535. As biomass is an often abundant, renewable, low ash and low sulfur fuel, biofuels are promising alternatives for traditional petroleum-based fuel applications; however, traditional biofuels for internal combustion engines are not cost comoetitive with gasoline. diesel or fuel oils. One method to reduce the cost oi biofuels is to use slurry fuels which have a potential lower cost than liquid biofuels due to high conversion efficiencies. Slurry biofuels, such as a mixture of corn and water, could provide a biofuel alternative for diesel engines pressurized gasifiers and heating oil applications such as burners or gas turbines. Use of these biomass slurries poses important questions about their stability and suitability for practical applications in internal combustion engines and combustors. This work reports rheological data for stable corn-starch water slurries (CSWS) which used a polyacrylate acid thickener to eliminate settling of the slurry and to provide desirable shear-thinning behaviour for most of the compositions evaluated. The effect of shear rate on the viscosity of the CSWS was studied using a BOHLINcontrolled stress (CS) rheometer. The well-known Ostwald-de Waele power law and Sisko models for viscosity fit the data. The favourable shear thinning properties were observed for starch contents up to 45% starch and should aid pumping, injection and spraying. The heating values of the slurries, however, are undesirably low. 98/02208
Stabilisation of biofuel ashes for recycling to forest
soil fSS5ui,
B.-M. and Lindqvist,
0.
Biomass and Bioenergv,
1997, 13, (l/2),
For several years a Swedish research programme concerning the technical and ecological effects of wood fuel ash recycling to forest biotopes has been carried out. Within this oroeramme. a studv of the stabilization of ash bv the so-called self-harder&g r)rocess was cariied out. Based on results from chemical analysis, X-ray diffraction, FTIR spectroscopic and scanning electron microscopy analysis, the chemical reactions oc&rring in the ash materials on water addition and during solidification were identified. The stability and importance of the individual reaction products are discussed.
Fuel and Energy Abstracts
May 1998
199