Turbine Bypass Valve

Turbine Bypass Valve

  • In case of failure or malfunction of a turbine, turbine bypass valves are used to reduce the pressure and temperature of the steam medium.
  • The medium is then diverted via the bypass line directly into the medium-pressure system or into the condenser.
  • BOMAFA turbine bypass valves feature a separation of the pressure-reduction process from the cooling process.
Pressure Reduction

The pressure reduction process is characterized by various decompression stages, thereby ensuring that the decompression remains sub-critical throughout the system. The first sub-critical decompression of the medium is effected by the perforated flow restrictor of the spindle. Its exact shaping depends on the through-flow specifications to which the valve is designed. The second sub-critical decompression is effected by the seat bushing, the total controllability of which is achieved by the control flange on the elongated valve spindle.

  • The perforated bushes are located underneath the seat bushing and fastened in place so that they cannot be turned out of position
  • The hot steam medium is forced to change direction between decompression stages, causing decompression which is kept sub-critical by the special arrangement of surface ratios between the stages.
  • The division of the decompression perforated bushes into individual chambers ensures that the medium may only load the intended chambers.
  • This facilitates low-noise and low-vibration operation throughout the load range.

Cooling Hot Steam

  • Motive steam cooling
    • Internal-mixing motive steam nozzle (two-component nozzle)
    • Atomisation of water using motive steam for short vaporisation distances
  • Pressure Atomisation
    • Pressurised atomisation with a variable spring-loaded nozzle
    • Swirl atomisation

For all desuperheating systems we can provide an optional lined version to prevent heat-shock cracks in the steam pipeline.

nominal
diameter
 inlet outlet
DN 25-600 / 1"-24" DN 50-2500 / 2"-100"
nominal
pressure
 PN 16-630 / Ansi 150-4500 lb/sq.in PN 16-630 / Ansi 150-4500 lb/sq.in
material 1.0460/A 105 - 1.5415/A 182 F1 - 1.7335/A 182 F12 - 1.7380/A 182 F22 - 1.4903/A - 182 F91 - 1.4901/A 182 P92
piping connection
 welding ends or flanges in all designs possible
characteristic
 equal percent / linear / customer-specific
seat-spindle thightening
 metallic - leakage class IV or V - spindel gasket Pure graphite
throttling element
 three-tages fully controlled with additional hole bushes or perforatet up to 10 pressure stages
ratio 1:10 - 1:25 - 1:50 - 1:100
actuator
 pneumatic - electrical - multiturn - electrical - linear up to orifice plates - hydraulic - lever