Development and technical progress in large-scale circulating fluidized bed boiler in China

Circulating fluidized bed (CFB) boilers has realized the clean and efficient utilization of inferior coal like gangue and coal slime, high sulfur coal, anthracite, petroleum coke, oil shale and other resources. As a country with the largest amount of CFB boilers and the largest installed capacity in the world, China has 440 100-600 MWe CFB boilers with a total capacity of 82.29 GW(e), including 227 units of 135 MWe, 95 units of 300 MWe, and 24 supercritical units. The statistics of typical 100-300 MWe CFB boilers showed that the average number of unplanned shut-down was only 0.37 times per year, among which the 135 MWe was 0.26 times per year and 300 MWe was 0.46 times per year. The auxiliary power ratio of some 300 MWe CFB boilers based on flow-pattern reconstruction can be reduced to about 4%, which is closed to the same level of pulverized coal (PC) boilers. This paper summarizes the development process and application status of China's large-scale CFB boilers, analyzes the characteristics and technical performance of the iconic units, and introduces solutions to the problems such as water wall wear and bottom ash cooling.