Pressure-Reducing and Desuperheating Stations

The pressure-reducing and desuperheating stations (PRDS) and fast-response pressure-reducing and desuperheating stations (FRPRDS) are used in circuits of power generating units for reduction of pressure and steam temperature to the preset parameters.

The desuperheating stations (DS) provide only the steam temperature reduction, while the pressure-reducing stations (PRS) ensure only steam pressure reduction.
PRDSs are used for boiler lighting-up, reservation of production bleedings of turbines in the circuits of power generating units of medium and low pressure, steam discharge to the production bleedings, for own needs of power generation plants and in case of absence of other steam sources with the required parameters.

FRPRDSs are designed for discharge of steam which is produced by a boiler or steam generator, but not consumed by the turbine on start-up and variable modes of the unit. The steam goes into the steam receivers of the condenser or in the auxiliary collector of the unit for power reservation of driving turbines of the feed pumps and blowers, as well as for the steam supply for heating-up of the intermediate superheating pipelines.

An installation set may include:

• A shutoff gate on the station inlet and outlet.
• A control valve on the live steam line or a control valve with combined reducing and cooling functions (on the live steam line).
• A steam desuperheater with nozzles.
• A throttling device.
• Gate control and check valves, filters installed on the injection line of cooling
  water.
• Valves on the drain lines.
• PC or POSV (on the reduced or cooled steam line).
• Pipeline elements for connection of all items to a complete whole.

The specific composition of valves of PRDS (FRPRDS, DS, PRS) is determined on the basis of terms of reference (configuration data sheet).

Gate
2. Control valve (steam)
3. Steam desuperheater or noise damper unit with throttle-cooling grid
4. Pressure safety valve
5. Pulse valve
6. Control valve (water)
7. Gate valve
8. Needle valve
9. Filter
10. Check valve