To explore suitable pipe-blowing methods for ultra supercritical double-reheat units

a decompression combined pipe-blowing method was proposed and put into practice on the domestic first double-reheat boiler. This new method is a combination of "one section pipe-blowing" method's structure and "two-section pipe-blowing"method's operating characteristics. The superheater

primary reheater

secondary reheater and its associated pipelines were connected in series in one time. The whole system is divided into three parts

and each part is purged and targeted separately. For the problem that the steam purge coefficient does not satisfy the standard

field test and theoretical analysis were carried out. Some measures

such as increasing the separator outlet steam pressure

opening multiple valves simultaneously

were taken into practice to eliminate the blocking flow effect and guarantee the purging quality. The final target plate tests results show that

the depression combined pipe-blowing method completed the purging of double-reheat boiler heating surfaces with high quality. This method can provide practical reference for other similar units.