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| 2. |
- Andersson, Sven B, 1952, et al.
(författare)
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N2O-Emissions from Fluidized Bed Combustion
- 1988
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Ingår i: Proceedings of IEA AFBC Technical Meting held in November 1988 in Amsterdam, The Netherlands.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Nitrous oxide, N20, is formed during combustion. In flames the N20 is removed because of the fast destruction at high temperatures. At the temperatures of fluidized bed combustion the destruction is much slower and N20 will leave the system, normally at a concentration of 50-200 ppm when burning coal. Using the results of the preliminary model in a CFB, it can be assumed that:- N20 is formed from char nitrogen in the bottom bed because of reactions in the pores of the particle. - Only some N20 is formed when NO is reduced during its journey up through the combustion chamber. - N20 is formed from HCN. This is a slow process (taking seconds) and it therefore takes place principally above the bottom bed.
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| 3. |
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| 4. |
- Borodulya, A.V., et al.
(författare)
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Densified Biofuel - an Alternative Source of Environmentally Sound and Renewable Energy
- 2003
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Ingår i: III International conference "Industrial Heat Engineering".
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Konferensbidrag (refereegranskat)abstract
- Advantages of densified biofuels as promising renewable and environmentally sound source for sustainable heat and power generation are discussed. Combustion characteristics of single particles of seven pelletised and three natural biofuels in a fluidized bed have been experimentally studied. The data obtained are described by mathematical models of devolatilisation and char combustion and empirical correlations.
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| 5. |
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| 6. |
- Dam-Johansen, Kim, et al.
(författare)
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Influence of SO2 on the NO/N2O chemistry in fluidized bed combustion 2. Interpretation of full-scale observations based on laboratory experiments
- 1993
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Ingår i: Fuel. - 0016-2361. ; 72:4, s. 565-571
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Tidskriftsartikel (refereegranskat)abstract
- In circulating fluidized bed combustion of coal, significant interactions between desulfurization by limestone and emissions of nitrogen oxides (NO, N2O) are generally observed. In order to facilitate interpretation of experimental results obtained in a 12 MW circulating fluidized bed boiler, a series of laboratory tests have been carried out. The tests include homogeneous CO and HCN oxidation in the presence of different concentrations of SO2, CO oxidation catalysed by calcined and partly sulfated limestone particles, and formation and reduction of NO and N20 over bed material containing char. The presence of SO2 in the gas is shown to decrease the rate of homogeneous CO and HCN oxidation and thereby change the product distribution of the nitrogen-containing species. Unlike sulfated limestone, calcined limestone (CaO) is shown to be a good catalyst for oxidation of CO. A lower mean CO concentration is therefore expected in fluidized bed combustors during injection oflimestone. This indirectly influences the nitrogen chemistry. Finally, the influence of NO and O2 on the formation of N2O from char was studied.
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| 7. |
- Davidsson, Kent, 1967, et al.
(författare)
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Countermeasures against alkali-related problems during combustion of biomass in a circulating fluidized bed boiler
- 2008
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Ingår i: Chemical Engineering Science. ; 63, s. 5314-5329
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this work was to study different ways to mitigate alkali-related problems during combustionof biomass in circulating fluidized beds. Wood chips and wood pellets were fired together withstraw pellets, while the tendency to agglomerate and form deposits was monitored. In addition to areference case, a number of countermeasures were applied in related tests. Those were addition of elementalsulphur, ammonium sulphate and kaolin to a bed of silica sand, as well as use of olivine sand andblast-furnace slag as alternative bed materials. The agglomeration temperature, composition and structureof bed-ash samples were examined. The flue-gas composition, including gaseous alkali chlorides, wasmeasured in the hot flue gases and in the stack. Particles in the flue gas were collected and analysed forsize distribution and composition. Deposits were collected on a probe in hot flue gases and their amountand composition were analysed. Addition of kaolin was found to be the best method to counteract theagglomeration problem. The deposition problem is effectively counteracted with addition of ammoniumsulphate, while kaolin is too expensive to be used commercially against deposits, and sulphur is lesseffective than ammonium sulphate.
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| 8. |
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| 9. |
- Davidsson, Kent, 1967, et al.
(författare)
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Potassium, chlorine, and sulfur in ash, particles, deposits, and corrosion during wood combustion in a circulating fluidized-bed boiler
- 2007
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 21:1, s. 71-81
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the addition of chlorine and/or sulfur to the fuel on fly ash composition, deposit formation, and superheater corrosion has been studied during biomass combustion in a circulating fluidized-bed boiler. The chlorine (HCl (aq)) and sulfur (SO2 (g)) were added in proportions of relevance for the potassium chemistry. The composition of the bottom and the fly ashes was analyzed. Gas and particle measurements were performed downstream of the cyclone before the convection pass and the flue gas composition was recorded in the stack with a series of standard instruments and an FTIR analyzer. At the position downstream of the cyclone, a deposit probe was situated, simulating a superheater tube. Deposits on the probe and initial corrosion were examined. It is concluded that addition of sulfur and chlorine increases the formation of submicron particles leading to deposition of potassium sulfate and chloride. The results compare well with earlier work based on laboratory-scale experiments concerning effects of chlorine and sulfur on potassium chemistry.
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| 10. |
- Elled, Anna-Lena, 1975, et al.
(författare)
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Influence of phosphorus on sulphur capture during co-firing
- 2006
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Ingår i: Fuel. ; 85, s. 1671-1678
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Tidskriftsartikel (refereegranskat)abstract
- Interference from phosphorus on sulphur capture during co-firing of sludge with wood has been investigated in a circulating fluidised bed boiler.Chemical equilibrium analyses were performed on the combustion system to complement the experimental results. It was found that the relativelyhigh content of phosphorus in municipal sewage sludge interferes with the sulphur capture by occupying calcium, which otherwise would beavailable for reaction with sulphur. This fact must be taken into account when sulphur capture strategies are decided for reduction of sulphurdioxide emissions from sewage sludge as an additional fuel.q 2006 Elsevier Ltd. All rights reserved.
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