Solids back-mixing in CFB boilers
Artikel i vetenskaplig tidskrift, 2007

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.

Wall layers

Scale-up

Modelling

Circulating fluidized bed

Fluidization

Particle

Hydrodynamics

Författare

Andreas Johansson

Chalmers, Energi och miljö, Energiteknik

Filip Johnsson

Chalmers, Energi och miljö, Energiteknik

Bo G Leckner

Chalmers, Energi och miljö, Energiteknik

Chemical Engineering Science

Vol. 62 561-573

Ämneskategorier

Maskinteknik