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Solids back-mixing in CFB boilers

Andreas Johansson (Institutionen för energi och miljö, Energiteknik) ; Filip Johnsson (Institutionen för energi och miljö, Energiteknik) ; Bo Leckner (Institutionen för energi och miljö, Energiteknik)
Chemical Engineering Science Vol. 62 (2007), p. 561-573.
[Artikel, refereegranskad vetenskaplig]

The furnaces of circulating fluidized bed (CFB) boilers have substantially lower height-to-width ratios than most of the laboratory CFB risers from which experimental investigations on riser fluid dynamics are published. Therefore, it is uncertain whether literature expressions for prediction of the distribution of solids and the thickness of the wall layers, derived from investigations in laboratory units, are applicable to boilers. In this work, data from laboratory units are compared with boiler data, and the accuracy of literature expressions for prediction of solids distribution, solids flow and wall layer thickness is reviewed. It is found that the height-to-width ratio does have a significant impact on the flow properties. Correlations based on experiments in laboratory units show poor agreement when applied to boilers. Modifications of literature expressions for prediction of solids flow and solids distribution are proposed, and an improved expression is formulated for prediction of the thickness of the wall layer.

Nyckelord: Circulating fluidized bed; Scale-up; Hydrodynamics; Modelling; Fluidization; Particle; Wall layers



Denna post skapades 2007-01-23. Senast ändrad 2016-08-15.
CPL Pubid: 25895

 

Institutioner (Chalmers)

Institutionen för energi och miljö, Energiteknik

Ämnesområden

Teknisk mekanik

Chalmers infrastruktur