| 1. |
- Brage, C., et al.
(författare)
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Tar evolution profiles obtained from gasification of biomass and coal
- 2000
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 18:1, s. 87-91
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Tidskriftsartikel (refereegranskat)abstract
- The tar content of the product gases from gasification of biomass is one of the major factors affecting the subsequent process stages. In this work, evolution profiles of the main tar constituents, i.e. benzene, toluene, indene, naphthalene and phenol were obtained during about 1 h gasification runs of biomass and coal in a pressurised fluidised-bed at 700 and 900 degrees C, 0.4 MPa. Sampling and analysis was achieved, using the solid-phase adsorption (SPA) method, previously developed in our laboratory. Our main objectives were: (1) to illustrate the usefulness of the SPA method; (2) to shed new light on the main factors governing tar evolution. It was found that temperature and the type of feedstock used mainly affected tar yields. For both biomass and coal the concentration of tar products decreased with increasing run time at a rate that was fastest initially. This behaviour, which was much more pronounced for coal, provides evidence that char catalytically affects tar evolution. Accordingly, char accumulates in the bed to a various extent depending on fuel and gradually approaching steady state. Biomass char, contrary to coal char, is readily oxidised during gasification, and thus only small steady-state amounts are available to catalyse tar cracking reactions.
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| 2. |
- 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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| 3. |
- Simell, P., et al.
(författare)
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Provisional protocol for the sampling and anlaysis of tar and particulates in the gas from large-scale biomass gasifiers. Version 1998
- 2000
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 18:1, s. 19-38
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents tar sampling protocols for pressurised and atmospheric large scale gasification processes. Methods for constructing sampling lines either to on-line analysers or into sampling systems are described. The tar sampling system consists of a heated probe, a particulate filter and a series of impinger bottles. Dichloromethane is used as the tar absorbing solvent. The solvent containing bottles are placed in a cold bath so that gradual cooling of the sampled gas from about 0 degrees C to the final temperature -79 degrees C takes place in them. Recommendations for suitable sampling gas flow rates and gas temperatures are given. Tar characterisation methods based on different garvimetric measurements and GC analysis are described.
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| 4. |
- Zanzi, Rolando, et al.
(författare)
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Rapid pyrolysis of agricultural residues at high temperature
- 2002
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Ingår i: Biomass and Bioenergy. - 0961-9534 .- 1873-2909. ; 23:5, s. 357-366
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with rapid pyrolysis of agricultural residues such as olive waste and straw at high temperature (800 -1000degreesC) in a free-fall reactor at pilot scale. The conditions are of interest for gasification in fluidized beds where rapid pyrolysis plays an important role as first stage. The objective of the work is to study the effect of the process conditions such as heating rate, temperature and particle size on the product distribution, gas composition and char reactivity. A higher temperature and smaller particles increase the heating rate resulting in a decreased char yield. The cracking of the hydrocarbons with an increase in the hydrogen content is favoured by a higher temperature and by using smaller particles. Wood gives more volatiles and less char than straw and olive waste. The higher ash content in agricultural residues favours the charring reactions. The higher lignin content in olive waste results in a higher char yield in comparison with straw. Chars from olive waste and straw are more reactive in gasification than chars from birch because of the higher ash content.
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| 5. |
- Liliedahl, Truls, et al.
(författare)
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Defluidisation of fluidised beds during gasification of biomass
- 2011
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 35:SUPPL. 1, s. S63-S70
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Tidskriftsartikel (refereegranskat)abstract
- Defluidisation and agglomeration during fluidised bed gasification of biomass is analysed and discussed. It is argued that the agglomeration and defluidisation processes, in principle, closely resemble those that determine the behaviour of glass during glass processing. Crucial properties for working with glass melts are the viscosity, stickiness, surface tension, etc. It is, however, (very) difficult to theoretically quantify these properties through thermodynamics or other theoretical means. Hence it will be problematic to theoretically predict agglomeration and defluidisation. Models for predicting defluidisation must therefore probably be of an empirical nature. As a consequence of this, a number of fluidised bed gasification tests were empirically analysed with respect to defluidisation. In total 145 tests were evaluated; of these 51 defluidised or exhibited some kind of bed disturbance. A number of fuels and bed materials were included in the analysis using a multivariate statistical approach.Based on the analysis an empirical regression equation for predicting the defluidisation temperature during fluidised bed gasification is suggested.
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