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| 2. |
- Hermansson, Sven, 1978, et al.
(författare)
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Combustion Disturbances Related to the Fuel Bed in Grate Furnaces
- 2005
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Ingår i: Swedish-Finnish Flame Days 2005. - 9171781854 ; 1:1, s. 150-158
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Combustion in grate furnaces is a common method for conversion of biofuels to energy, especially in small-scale heat production. In these furnaces combustion instabilities in the fuel bed are often observed. Here, an inventory is presented of combustion disturbances found in the fuel bed in grate furnaces. The inventory was carried out by interviewing personnel responsible for operation of ten furnaces and by recording of the fuel bed in eight of them by a portable video camera. Combustion disturbances were experienced in all except one of the furnaces. The most common disturbances were burnouts in the fuel bed and channelling at the bounding furnace walls. These disturbances are affected by practical factors related to the operation of grate furnaces. Those factors are presented together with suggestions for measures to reduce the frequency and magnitude of the disturbances. Digital image analysis was used to detect and quantify the size and movement of local burnouts in the fuel bed in one of the furnaces. The method can be used to find the source of disturbances or to evaluate contra-measures against burnouts.
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| 3. |
- Johansson, Robert, 1977, et al.
(författare)
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Limitations of the porous medium approximation in modelling of fixed bed combustion
- 2005
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Ingår i: Swedish - Finnish flamedays 2005. - 9171781854
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Most models for combustion of solid fuels in fixed beds treat the bed as a porous medium and neglect gradients within the fuel particles. There is no information about the conditions for which the description of the bed as porous medium is valid. To investigate this, a one-dimensional porous bed model is used together with a two-dimensional particle model. The two models are connected to each other through the surface temperature of the particle which is given by bed simulations. The main parameter is particle size, but the influence of moisture content and inlet gas velocity is also investigated. The results show that only particles smaller than around 5mm at low gas velocities can be treated as a porous medium, without considering internal gradients.
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| 4. |
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| 5. |
- Klason, T., et al.
(författare)
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A CFD simulation of a 31 MW district heating boiler
- 2005
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Ingår i: Swedish-Finnish Flame Days 2005, International Flame Research Foundation / edited by Åse Myrhinger. - 9171781854 ; , s. 237-251
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Rupar-Gadd, Katarina, et al.
(författare)
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Evaluation of the role of microbail activity in self-jheating of stored wood based biofuels
- 2005
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Ingår i: Swedish-Finnish Flame Days. - : International Flame Research Foundation. - 9171781854 ; , s. 262-267
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Konferensbidrag (refereegranskat)abstract
- Self-ignition in storde wood based biofuels is an environmental as well as an economical problem. The amount of biofuels, which is going to be stored, might increase due to the decision taken by the European Union that the emissions of greenhouse gases should decrease. Storage of oragnic material leads to chemical as well as microbial activities. The heat released from aged sawdust (stored outside for three months), dried mixture before it was pressed to pellets and three different kinds of pellets due to microbial activity was measurede with an isothermal calorimeter (TAM Air) under various conditions.- Experiments with and without addition of Cu,Fe and Mn were performed in order to investigate if a catalytical effect could be observed. The results showed that the addition of copper had different efffects depending on which wood material that was studied and the temperature at which the samples had been stored. The addition of Fe or Mn generally did not give any measurable increase in the heat released.
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| 7. |
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| 8. |
- Strand, Michael
(författare)
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Effects on CO and particle emissions by fuel sulphur addition in a moving grate boiler fired with forest residues.
- 2005
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Ingår i: Proceedings IFRF Swedish-Finnish Flamedays. - 9171781854 ; , s. 185-192
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Konferensbidrag (refereegranskat)abstract
- Increasing the sulphur content in the fuel by has been used in boilers fired with biomass in order to prevent high temperature corrosion. The higher sulphur content can be achieved by mixing with high sulphur fuels, e.g. coal or peat or by adding of various sulphur containing chemicals. An additional effect of increasing the sulphur content is that in some cases the emissions of soot, carbon monoxide (CO) and hydrocarbons have been shown to decrease. This has lead to an increasing interest in using sulphur addition as a method to reduce these emissions in medium sized grate boilers fired with biomass fuels, that for different reasons have problems to reach the legislated limits e.g. for CO emissions. However, there have also been a few reports suggesting that the emissions of fine particles in the submicrometer size range might increase with sulphur addition (Lindau and Skog, 2003). Since medium sized grate boilers often lack efficient devises for fine particle removal, there has been a concern that the positive effects on CO emissions by sulphur addition might be accompanied by enhanced particle emissions. In this study CO and particle emissions from a 7 MW boiler fired with moist forest residues with varying admixtures of elemental sulphur were characterised.
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