Study on heat transfer characteristics of the high temperature reheater tube panel in a 300 MW CFB boiler with fluidized bed heat exchanger

Abstract

On the basis of measurements on the fluidized bed heat exchanger (FBHE) of a 300 MW lean-coal-fired circulating fluidized bed (CFB) boiler under different thermal loads and numerical calculation for steam mass flow rate distribution inside the high temperature reheater (HTR) tube panels, the ash-side heat transfer coefficient distribution along the ash movement direction inside the FBHE was obtained in this paper. A cell model with energy and material balances was also developed for the FBHE. The measured and calculated results indicate that the post-combustion phenomenon exists in the FBHE. The ash-flow movement inside the FBHE has an important impact on the bed-to-tube heat transferring process. Specifically, along the ash moving direction, steam temperature at the outlet of corresponding tube panel decreases gradually, as well as the local ash-side heat transfer coefficient. These results can provide referential materials for design and operation of the FBHE in large-scale CFB boilers.