PRDS (Pressure Reducing & De-superheating Systems)

PRDS (Pressure Reducing & De-superheating Systems)

A Pressure Reducing and DeSuperheating Station (PRDS) is a system designed to take high-pressure, high-temperature steam from the boiler and reduce it to the required pressure and temperature for use in plant auxiliaries or industrial processes. This is accomplished by passing the steam through a pressure control valve (for pressure reduction) and then injecting atomized water into it (for temperature reduction).

How It Works

Pressure Reduction

Superheated steam is extracted from the main steam line and passed through a Pressure Control Valve (PCV). This valve throttles the steam, reducing its pressure to the desired operating level.

Desuperheating

The reduced-pressure steam is still at a high temperature. It then enters a desuperheater, where a controlled amount of finely atomized water is sprayed into the steam flow.

Steam Conditioning

The injected water rapidly evaporates, absorbing heat from the steam and lowering its temperature to the required set point, typically close to saturation temperature.

Purpose of the PRDS

Steam for Auxiliaries:
Various plant auxiliaries and systems require steam at specific pressures and temperatures that differ from the boiler output. The PRDS conditions the steam to meet these needs.
Steam Supply During Startup:
During boiler or turbine startup, the PRDS provides conditioned steam to essential auxiliaries such as gland seals and the deaerator when the main steam is not yet available or is at higher parameters.
Versatile Steam Supply:
By supplying steam at controlled pressure and temperature, the PRDS ensures safe and efficient operation of downstream equipment, preventing thermal stress or damage.

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