Bulk Density and Heat Transfer in Cirulating Fluidized Bed Boilers

摘要

In this study available theories and mathematical models are applied to results from measurements in full-scale boilers. A CFBB is defined as a boiler with a non-stationary bed, that is the bed material recirculates to an extent controlled by operating parameters such as the fluidizing velocity, the rate of aeration of an L-valve and the amount of bed material in the boiler. The thesis consists of the following parts: - A report on bulk density and heat transfer in CFBB's, this part. - Heat Transfer in FBB - discussion on models. Paper presented at the IEA meeting on mathematical modeling, Boston, May 1987. - Heat flow measurements in fluidized bed boilers. Paper presented at the 9th International Conference on Fluidized Bed Combustion, Boston, May 1987. A probe for Heat Flow Measurements in Fluidized Bed Boilers. Paper presented at the 14th IEA AFBC Technical Meeting, Boston, May 1987. The first part of the thesis concerns a bulk density and heat transfer study carried out on a CFBB. Flow regimes are discussed, and measurements of the bulk density and heat transfer distribution in a CFBB are presented together with results obtained with a mathematical model for calculating the heat transferred to the walls of the combustion chamber. The heat transfer model is presented in the second part. This paper also includes a comparison of the vertical bulk density distribution in a CFBB and an SFBB and a comparison with results obtained from a cold model. The third part consists of a comparison between the heat transfer in an SFBB and that in a CFBB. An investigation of the heat flow meters used is presented in the fourth part.