Abstract:

Coking occurs more frequently in the start-up process of circulating fluidized bed boiler （CFBB） with heavy oil ignition over bed. Based on a coking accident during the start-up process of a new CFBB, this paper analyzed the coking reasons that were improper wind-oil ratio, design defect of oil gun shield, incorrect positioning of oil gun, mixed burning time of oil and coal being too long, bad atomization of heavy oil gun, combustion adjustment being no in time in later coal feeding, et al. Finally, according to these reasons, the corresponding preventive measure of coking was put forward, whose effect was obvious: there was no coking in bed material and the region nearby oil gun shield.

Key words: circulating fluidized bed boiler, ignition over bed, heavy oil, coking