| 1. |
- Lyngfelt, Anders, 1955, et al.
(författare)
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Reduction of N2O Emissions from Fluidised Combustion by Reversed Air Staging
- 1995
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Ingår i: Second International Conference on Combustion and Emissions Control, The Institute of Energy, London. ; , s. 89-100
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Konferensbidrag (refereegranskat)abstract
- A new method, reversed air staging, for decreasing N2O from fluidised bed combustion, was investigated in a 12 MW circulating fluidised bed boiler. Previous measurements, showing that the N2O is decreased to one fourth (25 ppm), and NO to half(40 ppm) with maintained sulphur capture, were confirmed. Supplementary information on reversed air staging was obtained from additional measurements. By adjusting the temperature and the air ratio it was possible to reduce the CO emission. Thus, the N2O emission can be reduced to the level of 25 ppm, with the emissions of NO, SO2 and CO maintained at about same level as with normal air staging. Low load in combination with reversed air staging resulted in:further reduced emissions. The effect of reversed air staging on the emissions from peat is similar to that of bituminous coal. There is no negative effect of reversed air staging on the combustion efficiency.
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| 2. |
- Na, Yongjie, et al.
(författare)
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Large and small particles in CFB combustors
- 1996
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Ingår i: Proc of the 5th International Conference on Circulating Fluidized Bed. ; 5, s. 194-199
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Konferensbidrag (refereegranskat)abstract
- The behaviour of coarse particles was studied in a fluidized bed rig and in a 12 MW CFB boiler. Minimum fluidization velocity and the entrainment rate of course particles from a bed with and without fine sand were measured in the cold rig. A series of solid samples were talen from the boiler furnace in different points with suction probes under various test conditions. The amount of coarse particles was analysed. Bulk densities at different heights with and without coarse particles were compared. It was found that both the minimum fluidisation and terminal velocities were influenced by the flux of fine particles.
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| 3. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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Fuel Loading of a Fluidized Bed Combustor Burning Bituminous Coal, Peat or Wood Chips
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Characterisation of gas- and particle phases in the combustion chamber of a commercial size circulating fluidized bed (CFB) boiler has been carried out during tests with three different fuels: bituminous coal, peat and wood chips, for typical operating conditions of a CFB boiler. The evaluation of the test results aims at presenting data on the fuel loading in parallel with the vertical profiles of oxygen concentration to be used for validation of models and for modelling of the fuel loading. The measurements show that the char loading during peat combustion is 13% of the amount found during coal combustion. Wood combustion results in even less char, only 3.5% of the concentration during coal combustion. For all fuels, more than 80% of the mass of char is retained in the lower part of the combustion chamber, below 2 meter from the bottom plate. The oxygen concentration profiles show large variations over the cross section for all three fuels, explained as an effect of insufficient penetration of secondary air in combination with partial plugging of some of the secondary air nozzles. In the peat and wood cases some of the variation over the cross section is caused by the high volatile content of the fuel in combination with a fuel supply from only one of the furnace walls.
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| 4. |
- Åmand, Lars-Erik, 1957, et al.
(författare)
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Measurement of the concentration of ammonia and ethene in the combustion chamber of a circulating fluidised-bed boiler
- 1997
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Ingår i: Journal of the Institute of Energy. ; :70, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of measuring the ammonia and ethene concentration profiles in the combustion chamber of a circulating fluidised-bed boiler. The boiler was operated in three air-staging conditions with peat as fuel, and with the addition of lime. Two sampling techniques were used for the analysis of ammonia: gas-sampling probe connected to a Fourier transformed infra-red (FTIR) instrument, and a gas-quenching (GQ) probe where the sample was quenched directly in the probe tip by a trapper solution. Both techniques are accurate enough to distinguish the influence on air staging of the level of ammonia in the combustion chamber. Comparison of the concentration profiles for ammonia measured by the two procedures shows similar results. The levels of ammonia and ethene measured by FTIR follow each other in the combustion chamber for all three staging conditions. The FTIR spectra were evaluated by three methods: spectral subtraction, differential absorbance and the multiple variable analysis method named 'partial least square' (PLS). Almost equal levels of concentration of ammonia and ethene were found, regardless of the method employed. The measurement error from reactions with ammonia at the GO probe tip was estimated in a simple model.
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