| 11. |
- Gabra, M., et al.
(författare)
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Evaluation of cyclone gasifier performance for gasification of sugar cane residue : Part 2: Gasification of cane trash
- 2001
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 21:5, s. 371-380
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Tidskriftsartikel (refereegranskat)abstract
- In Part 1 of this two-part paper, results from gasification of bagasse in a cyclone gasifier have been reported. In this paper results from gasification of cane trash in the same cyclone gasifier are presented. The cane trash powder is injected into the cyclone with air as transport medium. The gasification tests were made with two feeding rates, 39 and 46 kg/h at two equivalence ratios of 0.25 and 0.20 and the gasification temperature ranging from 820°C to 850°C. It was found that the heating value of the producer gas is in the range of 4.5-4.8 MJ/Nm3(dry gas), which is sufficient for stable gas turbine combustion. Significant alkali separation has been achieved in the cyclone stage. However, the alkali levels and carryover particle concentrations in the producer gas were found to be higher than allowable in a gas turbine. Despite high ash melting temperatures found by the TGA-DTA, deposition problems cannot be excluded since some carryover panicles in the producer gas seem to have been melted and since some gasification of K and Na compounds is indicated. As an overall assessment, cane trash appears as a more problematic fuel than bagasse for this application. Integrated experiments with a gas turbine need to be done for accurate evaluation of the possibilities to use the producer gas from the gasification of cane trash to run a gas turbine without problems of hard deposits and corrosion on the turbine blades. © 2001 Published by Elsevier Science Ltd.
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| 12. |
- Hassan, Salman, et al.
(författare)
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Pneumatic conveying of wood powder by using a steam-jet ejector
- 2000
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 19:2, s. 103-117
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Tidskriftsartikel (refereegranskat)abstract
- Wood powder and sawdust are two fuels which will be tested in a pressurized cyclone-gasifier. The gasifier will be a part of combined cycle power plant where a gas turbine is run by the product gases from the gasifier and a steam boiler will use the exhaust gas from the turbine. To inject the fuel into the cyclone, a steam-jet ejector seems to be appropriate due to its simplicity and the possibility of using the steam produced by the boiler for feeding of the fuel. Three types of wood powder with different particle-size distribution have been tested in different ejector geometries. The results show that the steam-jet ejector is suitable as a feeding pump for wood powder and sawdust. For commercial wood powder fuel with particle size below 1 mm, a powder to steam mass flow ratio of about 25 and with coarser sawdust a mass flow ratio of at least 10 can be reached. The pressure gain required to overcome the pressure drop in the cyclone gasifier can be achieved. The relative pressure gain seems to be independent of the size distribution of the particles.
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| 13. |
- Joppich, A., et al.
(författare)
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Wood powder feeding, difficulties and solutions
- 1999
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 16:3, s. 191-198
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Tidskriftsartikel (refereegranskat)abstract
- A pneumatic fuel feeding system for wood powder fired gas turbines was incorporated at the Vienna University of Technology. One of the most important requirements of fuel feeding is a very homogeneous mass flow of wood powder. Therefore, the performance of the mechanical conveying part of the feeding system has been studied experimentally at flow rates corresponding to the operation range. Beside screw feeding, a vibrator is used to homogenize the flow rate. While the screw feeder shows large fluctuations, the vibrator conveyer reduces them considerably. The tests also show that for each flow rate a certain optimum amplitude of the vibrator exists at which the fluctuations reach a minimum. Furthermore, a linear function is observed between optimum oscillation amplitude and feeding rate.
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| 14. |
- Koullas, D.P., et al.
(författare)
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Effect of alkali delignification on wheat straw saccharification by fusarium oxysporum cellulases
- 1993
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 4:1, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- The effect of alkaline delignification of wheat straw on the chemical composition and the subsequent enzymic hydrolysis of the pretreated straw are reported. Both hot (120°°C) and cold (20–36°°C) delignification were investigated, using either aqueous or organic alkaline solutions. The treated lignocellulosic materials were hydrolyzed by the cellulases of Fusarium oxysporum strain F3. Both delignification and saccharification yield showed linear relationships with the level of alkali used. Under the chosen experimental conditions 70–100% hydrolysis was achieved either by hot or cold delignification. Delignification to at least 50% appeared crucial for total polysaccharide conversion.
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| 15. |
- Lagerkvist, Anders
(författare)
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Landfill gas activity of the IEA bioenergy agreement
- 1995
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 9:1-5, s. 399-413
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Tidskriftsartikel (refereegranskat)abstract
- Landfill gas (LFG) is a renewable source of useful energy. Its world wide annual energy potential is in the range of a few hundred TWh. Today it is only marginally exploited. LFG is also an important contributor to the atmospheres CH4-content, it can be estimated to contribute about 25% of the methane coming from anthropogenic sources. In comparison to many other sources of methane emissions such as peat bogs, rice paddies, termites and sheep, landfills can be considered to be point sources, i.e. they are stationary and of limited extension. For this reason landfill gas (LFG) utilisation is one of the most cost effective ways to combat the greenhouse effect. The aim of the IEA activity on LFG is to promote information exchange and co-operation between national programmes in order to promote the proliferation of landfill gas utilisation. During the period 1992–1994 the LFG activity has had six participating countries: Canada, Denmark, Norway, The Netherlands, Sweden, UK and USA. In the past three-year period, the activity has been mainly directed towards establishing networks and obtaining an over-view of data related to LFG in the member countries. Numerous contacts have been established and perhaps of most importance for the future of the activity are the links towards organisations involved in the development of landfill technology, such as ISWA and SWANA. The gathering and evaluation of data within the LFG area from the member countries has resulted in a number of documents that are to be published within the near future. These documents cover information on LFG utilisation, landfill research, landfill gas potentials, landfill emission assessment and also non-technical barriers to LFG utilisation.
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| 16. |
- Lundgren, Joakim, et al.
(författare)
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Experimental studies during heat load fluctuations in a 500 kW wood-chips fired boiler
- 2004
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 26:3, s. 255-267
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Tidskriftsartikel (refereegranskat)abstract
- Several long-term experiments with fluctuating thermal outputs have been carried out in a newly developed biomass fuelled boiler suitable for small district heating networks. The experiments have been performed by either using the furnace only or the furnace together with a water heat store. Comparisons between these two operation strategies have been made concerning emissions and overall performance. Furthermore, the plant has been run to match a simulated heat demand during different seasons, in order to study the performance of the system during more realistic operation conditions. The results are very satisfactory concerning both performance and emissions, using any of the control strategies. Typical emissions of CO and NOx during the experiments are in the range of 10–50 mgNm−3 (5–25 mgMJ−1) and 130–175 mgNm−3 (60–90 mgMJ−1), respectively. However, during summer when the heat demand is low or zero, operational problems will occur if the heat store is excluded. Therefore, the main conclusion is that the most appropriate solution for a small district-heating system is to use a water heat store to match the heat load variations, while the furnace operates at as constant thermal output as possible.
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| 17. |
- Mamma, D., et al.
(författare)
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An alternative approach to the bioconversion of sweet sorghum carbohydrates to ethanol
- 1995
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 8:2, s. 99-103
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Tidskriftsartikel (refereegranskat)abstract
- The ethanol fermentation of juice and press cake, resulting from the squeezing of sweet sorghum stalks at high pressure, was investigated. The juice was fermented by Saccharomyces cerevisiae and yielded 4.8 g ethanol per 100 g of fresh stalks. The press cake was fermented directly to ethanol by a mixed culture of Fusarium oxysporum and Saccharomyces cerevisiae and yielded 5.1 g ethanol per 100 g of fresh stalks. An overall ethanol concentration and yield of 5.6% (w/v) and 9.9 g of ethanol per 100 g of fresh stalks respectively was obtained. Based on soluble carbohydrates, the ethanol yield from press cake was doubled while the overall theoretical yield was enhanced by 20.7% due to the bioconversion of a significant portion of cell wall polysaccharides to ethanol. The process was found promising for further investigation.
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| 18. |
- Myrén, Carin, et al.
(författare)
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Catalytic tar decomposition of biomass pyrolysis gas with a combination of dolomite and silica
- 2002
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 23:3, s. 217-227
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Tidskriftsartikel (refereegranskat)abstract
- In this study the catalytic effects of dolomite and silica on biomass tar decomposition were investigated. The concentration of naphthalene is of particular interest since it is the most difficult compound to decompose when dolomite is used as catalyst. The two catalysts were tested in different combinations to see whether synergetic effects on the cracking of naphthalene could be found. Thermal and catalytic cracking were carried out at 700-900degreesC under ambient pressure in a fixed bed reactor using a tar-rich gas obtained from pyrolysis of different biomass materials. Characterisation of light components of tars using the solid phase adsorption method was also performed. Experimental results indicate that when a pure silica is placed in a layer above the dolomite, considerably less naphthalene and total light tar remains after cracking.
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| 19. |
- Möllersten, Kenneth, 1966-, et al.
(författare)
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Potential market niches for biomass energy with CO2 capture and storage : Opportunities for energy supply with negative CO2 emissions
- 2003
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 25:3, s. 273-285
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents an analysis of biomass energy with CO2 capture and storage (BECS) in industrial applications. Sugar cane-based ethanol mills and chemical pulp mills are identified as market niches with promising prospects for BEGS. Calculations of CO2 balances of BECS in these applications show that the introduction of CO2 capture and storage in biomass energy systems can significantly increase the systems' CO2 abatement potentials. CO2 emissions of the total systems are negative. The CO2 reduction potentials of these technologies are discussed in regional and global contexts. An economic assessment of each system is carried out and opportunities for cost-effective technologies for CO2 capture, transportation and storage are identified. Furthermore, potentials for system improvements that could substantially decrease the CO2 abatement cost are addressed.
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| 20. |
- Natarajan, E, et al.
(författare)
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Experimental determination of bed agglomeration tendencies of some common agricultural residues in fluidized bed combustion and gasification
- 1998
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 15:2, s. 163-169
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Tidskriftsartikel (refereegranskat)abstract
- Ever increasing energy demand and the polluting nature of existing fossil fuel energy sources demonstrate the need for other non-polluting and renewable sources of energy. The agricultural residues available in abundance in many countries can be used for power generation. The fluidized bed technology seems to be suitable for converting a wide range of agricultural residues into energy, due to its inherent advantages of fuel flexibility, low operating temperature and isothermal operating condition. The major ash-related problem encountered in fluidized beds is bed agglomeration which, in the worst case, may result in total defluidization and unscheduled downtime. The initial agglomeration temperature for some common tropical agricultural residues were experimentally determined by using a newly developed method based on the controlled fluidized bed agglomeration test. The agricultural residues chosen for the study were rice husk, bagasse, cane trash and olive flesh. The results showed that the initial agglomeration temperatures were less than the initial deformation temperature predicted by the ASTM standard ash fusion tests for all fuels considered. The initial agglomeration temperatures of rice husk and bagasse were more than 1000°C. The agglomeration of cane trash and olive flesh was encountered at relatively low temperatures and their initial agglomeration temperatures in gasification were lower than those in combustion with both bed materials. The use of lime as bed material instead of quartz improved the agglomeration temperature of cane trash and olive flesh in combustion and decreased the same in gasification. The results indicate that rice husk and bagasse can be used in the fluidized bed for energy generation since their agglomeration temperatures are sufficiently high.
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