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Bottom bed regimes in a circulating fluidized bed boiler

Anders Svensson (Institutionen för energiomvandling) ; Filip Johnsson (Institutionen för energiomvandling) ; Bo Leckner (Institutionen för energiomvandling)
International Journal of Multiphase Flow (0301-9322). Vol. 22 (1996), 6, p. 1187-1204.
[Artikel, refereegranskad vetenskaplig]

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.

Nyckelord: circulating fluidized beds; fluidization regimes; bubbling beds; fluid dynamics; fluctuations

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Denna post skapades 2016-06-24. Senast ändrad 2016-08-15.
CPL Pubid: 238262


Institutioner (Chalmers)

Institutionen för energiomvandling (1900-2003)


Termisk energiteknik

Chalmers infrastruktur

Chalmers Kraftcentral (CK)