Шляхи удосконалення ущільнень для підвищення експлуатаційної безпеки насосів АЕС

Abstract

. The sealing unit is a complex system, on which reliability, safety and durability of the pump unit is largely depend. An analysis of the existing designs of sealing units for nuclear power plants (NPP) pumps was carried out, which showed that the most widespread were hydrostatic and mechanical face seals with improved lubrication conditions. Hydrostatic seals are used as main seals for throttling high pressure. Mechanical face seals, due to their low leakage, are mainly used as closing seals. The most promising areas of sealing units design for NPP pumps have been identified. It has been determined that when choosing a seal design, it is necessary to take into account not only their direct function, that is to reduce leakages, but to provide the necessary vibration characteristics of the pump as well, it being their equally important function. The most promising is the hydrostatic seal with impulse balancing of the axially movable ring, which, when the shaft rotates, provides contactless operation with low leakage, and when stationary, it provides complete tightness. A unified approach to its computation has been developed, which is reduced to the plotting of static characteristics, that is, the dependence of the gap and flow rate on external influences, and the determination of the coefficients of static and dynamic stiffness. This makes it possible to identify dangerous ranges of rotation speeds and select the parameters of the seal so that the forced axial vibrations amplitudes of the ring should not go beyond the permissible limits. Some examples of industrial application of sealing systems based on impulse seals, that provide the necessary tightness, reliability and environmental safety in extreme conditions typical for NPP pumping equipment, have been given