The impact of bed temperature on heat transfer characteristic between fluidized bed and vertical rifled tubes

What is it about?

In the present work, the heat transfer study focuses on assessment of the impact of bed temperature on the local heat transfer characteristic between a fluidized bed and vertical rifled tubes (38mm-O.D.) in a commercial circulating fluidized bed (CFB) boiler. Heat transfer behavior in a 1296t/h supercritical CFB furnace has been analyzed for Geldart B particle with Sauter mean diameter of 0.219 and 0.246mm. The heat transfer experiments were conducted for the active heat transfer surface in the form of membrane tube with a longitudinal fin at the tube crest under the normal operating conditions of CFB boiler. A heat transfer analysis of CFB boiler with detailed consideration of the bed-to-wall heat transfer coefficient and the contribution of heat transfer mechanisms inside furnace chamber were investigated using mechanistic heat transfer model based on cluster renewal approach. The predicted values of heat transfer coefficient are compared with empirical correlation for CFB units in large-scale.

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Why is it important?

This work addresses an existing gap in the literature data regarding the modelling of and experimentation of heat transfer to tubes in furnace chamber [2-6], by providing experimental data from CFB unit in a large-scale. The high labour intensity and cost of carrying out large commercial-scale tests are the cause of the lack of publications of the results of investigations of heat transfer processes on a large commercial scale. In this situation, carrying out comprehensive studies would make it possible to establish the optimal heat transfer conditions in correlation with the bed hydrodynamics.