Start-up system is a key technology for supercritical and ultra-supercritical boilers.Start-up systems in all kinds of once-through boilers were comprehensively classified.Furthermore

technical features and safety of each start-up system were qualitatively compared.Especially

the economic efficiency and start-up speed of supercritical and ultra-supercritical boilers were quantitatively calculated.The results showed that

supercritical and ultra-supercritical boilers adopting start-up system with boiler water circulating pump(BCP)was clearly superior in economy and start-up speed.Compared with the simple start-up system with atmospheric expanding device

the system with BCP had lower heat loss and higher start-up speed

and it can increase about three hours'power generation capacity during one warm state start-up under the same conditions.Therefore

the start-up system with BCP is the best choice for supercritical and ultra-supercritical boilers.