Prediction of the heat flux profile on the furnace wall of circulating fluidized bed boilers

The purpose of this work is to investigate and develop a correlation for predicting the profile of heat flux on the crest of the membrane water wall tube along the height of circulating fluidized bed furnaces. The heat conduction equation for the tube was solved numerically under various operating conditions and furnace sizes. It was found that the temperature and heat flux profiles decreased rapidly in the region above the secondary air ports and then were found to be nearly constant. In addition, the heat flux increased as the Froude number increased or as the bed particle to the furnace diameter ratio decreased. The results were used to develop a correlation for predicting the heat flux profiles of the boilers having capacities from 12 MWth to 165 MWth in terms of dimensionless temperature, the Froude number, the diameter ratio and the height from the ports to the total height ratio.