Mechanical seals for condensate pumps

Condensate pumps are employed at power stations in the main condensate circuit and in the secondary condensate recycling system. Their job is to remove under vacuum the steam precipitating in the condenser as water (condensate). The typical condensate pump is a centrifugal pump usually of vertical arrangement (main condensate pump). It has only one seal (practically always a mechanical seal) positioned on the pump pressure side. When condensate pumps are at standstill, the mechanical seal is usually under vacuum, so steps must be taken to provide lubrication of the sliding faces in this state, i.e. even after the medium falls, condensate must be present at the mechanical seal for the restarting phase. It is also necessary for the stationary seat to have a stationary seat lock. The mechanical seals used for condensate pumps are single-acting designs with quenching fluid, tandem arrangements with pressureless quenching fluid, and double-acting designs with buffer system.