| 1. |
- Johnsson, Filip, 1960, et al.
(författare)
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Fluidization regimes in boilers
- 1995
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Ingår i: Preprints of Fluidization VIII. ; , s. 129-136
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The fluid dynamics were studied in a fluidized bed boiler and in two laboratory fluidized beds under ambient conditions. The beds had different geometries but were all of a non-slugging type operated with Geldart Group B and D particles. The bed geometry was found to strongly influence the fluid dynamics of the bed.
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| 2. |
- Johnsson, Filip, 1960, et al.
(författare)
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Optical and momentum probe measurements in a CFB boiler
- 1996
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Ingår i: Proc of the 5th International Conference on Circulating Fluidized Bed. ; , s. 652-657
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Konferensbidrag (refereegranskat)abstract
- Methods for the characterization of the two-phase flow in the transport zone of circulating fluidized bed (CFB) boilers are discussed based on measurements of fluctuations in local solids concentration and momentum flux using an optimum probe and a momentum probe. Both probes were designed to withstand the environment inside a furnace during combustion. The dynamic information on the flow obtained by the two probes was in agreement. The time-resolved measurements in the core region as well as in the wall layer by continuous increases and decreases in solids concentration and momentum flow from a base level at low solids concentration.
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| 3. |
- Svensson, Anders, 1960, et al.
(författare)
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Bottom bed regimes in a circulating fluidized bed boiler
- 1996
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Ingår i: International Journal of Multiphase Flow. - 0301-9322. ; 22:6, s. 1187-1204
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Tidskriftsartikel (refereegranskat)abstract
- This paper extends previous work on the fluidization regimes of the bottom bed of circulating flyidized bed (CFB) boilers. Pressure measurements were performed to obtain the time-average bottom bed voidage and to study the bed pressure fluctuations. The measurements were carried out in a 12 MWth CFB boiler operated at 850°C and also under ambient conditions (40°C). Two bubbling regimes were identified: a “single bubble regime” with large single bubbles present at low fluidization velocities, and, at high fluidization velocities, an “exploding bubble regime” with bubbles often stretching all the way from the air distributor to the surface of the bottom bed. The exploding bubble regime results in a high through-flow of gas, indirectly seen from the low average voidage of the bottom bed, which is similar to that of a stationary fluidized bed boiler, despite the higher gas velocities in the CFB boiler. Methods to determine the fluidization velocity at the transition from the single to the exploding bubble regime are proposed and discussed. The transition velocity increases with an increase in particle size and bed height.
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| 4. |
- Svensson, Anders, 1960, et al.
(författare)
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Fluidization regimes in non-slugging fluidized beds: the influence of pressure drop across the air distributor
- 1996
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Ingår i: Powder Technology. - 1873-328X .- 0032-5910. ; 86:3, s. 299-312
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present work is to study the influence of the pressure drop across the air distributor on the bubbling conditions of thebottom bed of circulating fluidized beds (CFB). The bottom bed is the dense bubbling zone just above the distributor. The experimental workwas carried out in a 12 MWm CFB boiler and in a cold CFR Three different distributions of the bubble flow in time and space, termedfluidization regimes, were identified in the cold CFB: the multiple bubble regime with many small bubbles evenly distributed in the bed; thesingle bubble regime, characterized by the presence of only one bubble at a time in the bed; and the exploding bubble regime with large,single, irregular voids stretching from the air distributor to the bed surface. These bubbling conditions were observed during variations in thegas velocity and the distributor pressure drop. A comparison with the 2 mz cross-section CFB boiler showed that the boiler always operatesin the single or in the exploding bubble regime, which indicates a bubble flow that is not continuous and not well distributed over the crosssectionof the bed. The conditions in the boiler are influenced by the relatively large area of gas passage and the low pressure drop of theboiler air distributor.
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| 5. |
- Johnsson, Filip, 1960, et al.
(författare)
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Air-plemum pressure fluctuations in a circulating fluidized bed boiler
- 1997
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Ingår i: Proc of the 2nd European Conference on Fluidization. - 8475859259 ; , s. 223-230
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Konferensbidrag (refereegranskat)abstract
- Interactions between in-bed (furnace) and air-plenum pressure fluctuations were studied in a 12 MWth CFB boiler under various operation conditions. The influence of a change in the characteristics of the air-feed system was studied by changing the pressure drop of the air-distributor dpdist, by means of equal throttling of all nozzles of the air-distributor. The measured pressure fluctuations were characterized by amplitude and power spectra.
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| 6. |
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| 7. |
- Johnsson, Filip, 1960, et al.
(författare)
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Characteristics of the formation of particle wall-layers in CFB boilers
- 1995
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Ingår i: Proc of the 2nd International Conference on Multiphase Flow. ; 3, s. FB1-25-FB1-32-
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Konferensbidrag (refereegranskat)abstract
- The character of the vertical two-phase flow in circulating fluidized bed (CFB)boiler furnaces is compared with results from small CFB risers presented in literature. The particle flow in furnaces as well as in the smaller risers shows a core/wall-layer structure. In the CFB boilers the particle flow pattern develops up through the furnace with the major back-flow caused by separation to the furnace walls. Both the particle wall-layer thickness and the downward flux within this layer increase downwards along the furnace walls. In the smaller units this downward increase is either absent or much smaller, a consequence of a more developed particle flow profile, which, typically, is parabolic in shape.
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| 8. |
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| 9. |
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| 10. |
- Johnsson, Filip, 1960, et al.
(författare)
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Solids segregation in a CFB-boiler furnace
- 1998
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Ingår i: Fluidization IX / Fan, L-S., Knowlton, T.. - 0939204568 ; , s. 757-764
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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