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Case Study

Power plant

A gas-fired cogeneration power plant in Germany replaced turbine drain valves to reduce steam and energy losses.

Customer benefits


During turbine start-up, drain valves must be open to ensure large quantities of condensate generated during warm-up are removed quickly, to ensure rapid start-up to meet demand and avoid damage. This application requires reliable and robust severe service valves to discharge flashing water at high pressures, and then to have a tight shut-off when closed.

Any steam passing through the turbine drain valves once these are closed (known as leakage) will have an impact on the efficiency of the turbine. An energy and power generation company were experiencing leaks as a result of drain valve trim and seat erosion.

This was increasing maintenance time and spare part replacement cost. The leaks meant the customer was losing "high value" steam and energy from their turbine, and this was impacting the vacuum of the condenser downstream.

Contol valve for servere services


After walking the plant, GESTRA recommended replacing the existing turbine drain valves with GESTRA's ZK 313 as a drain and warm-up valve solution; this would avoid leaks and steam losses, save energy, and ensure the vacuum of the condenser downstream was not being affected.

Summary of technical solution

  • Ideal for service applications in steam, condensate and water cycles
  • Handling of high differential pressure
  • Zero leakage tight shut off trim
  • Wear resistance trim parts against flashing water and 2-phase flow


The ZK 313 drain valve was able to operate reliably in this severe service drain application, ensuring efficient drainage at start-up followed by highly effective tight shut-off once the system was up-and-running.

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