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On the basis of measurements on the fluidized bed heat exchanger (FBHE) in a 600MW supercritical CFB boiler fueled by lean coal under different boiler load, the actual operation characteristics of the FBHEs, such as post-combustion characteristics and heat absorption shares in the FBHE were obtained in this paper, as well as ash flow rate through the FBHE. The measured and calculated results indicate that the post-combustion phenomenon exists in the FBHEs of the boiler fueled by lean coal. As steam parameter raises from subcritical to supercritical parameter, heat absorption share of heating surface in the FBHEs are quite different from each other regardless of boiler load. Moreover, as the boiler load decreases, ash flow rate through FBHE arranging reheater is almost the same, while ash flow rate through FBHE arranging superheater changes significantly. These results can provide referential materials for the optimized design and operation of the FBHE in large-scale CFB boilers.

To meet the requirements of the power grid’s deep peak shaving, a 300MW CFB boiler in a power plant transformed the flue gas recirculation. After the transformation, it is found that after putting into the flue gas recirculation, the main parameters of the boiler such as environmental protection emission value, the boiler operating bed temperature, and the inlet temperature of the separator had changed. To analyze the changes, this paper was carried out by related thermal state tests during the start-up or the normal operation of the boiler. The operating data of the boiler was collected before and after putting into the flue gas recirculation, and the influence of the gas recirculation on the main parameters and economic indicators of the boiler is quantitatively analyzed and discussed. The result shows that the technology of the flue gas recirculation can reduce the oxygen content in the dense phase area of the furnace and increases the reducing gas atmosphere to reduce the generation of NOX emission during the start-up or in the normal operation of the boiler. This provides a technical reference that optimizes the operation mode of the flue gas recirculation during the deep peak shaving in the CFB boiler.

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