Abstract: Abstract:The protection mechanism of ammoniahydrazine passivation drying method was introduced. It is difficult to keep the mass concentration of the hydrazine in required value during idle boiler preservation. Aiming at above problem, some measures, such as to adjust the equipment function, to improve the chemicals feed mode and others, were proposed. Taking the supercritical unit of Hunan Huadian Changsha Power Generation Company Limited as example, the implementation key points of the idle boiler preservation were given. The tubecut inspection data during overhaul show that the preservation result is favourable.

Key words: Keywords:supercritical unit, ammoniahydrazine passivation drying method, idle boiler preservation, hydrazine, passivation