Multi-Stage Vacuum System for Power Applications

Associated Equipment:

  • Steam valves
  • Vacuum service valves
  • Steam traps
  • Instrumentation
  • Flow measurement
  • Relief valves
  • Silencers
  • Y Strainers
Two Stage Twin Element Vacuum System Package designed for a capacity of 15.0 SCFM consisting of a high vacuum ejector, low vacuum ejector, hogging ejector, single shell inter/after condenser with dividing tubesheet


Multi-Stage Vacuum Systems for Power Applications are developed for the power industry for air removal from main turbine condensers.

Due to their large sizes and capacities, these systems are also applicable to the chemical, petrochemical, petroleum, pharmaceutical, food processing, and metal refining industries. These systems may also be modified for geothermal applications where high levels of H2S (hydrogen sulfide) and non-condensable gases in the motive and suction streams call for special materials and design considerations.

Vessel evacuation and vacuum conditions are achieved by two steam jets operating in series. These jets are specifically designed to handle the rated capacity of the standard units or per customer requirements. Variations in the standard system set up, i.e., twin element, 200% condensers etc., does not impact the standard sizing of the steam jets since each jet in a twin element system handles 100% of the design load. Other capacity combinations (e.g., 40 – 60% ejectors or 2 – 75% ejectors, etc.) may be accommodated upon request.


Every Schutte & Koerting standard two-stage vacuum system is supplied with a shell and tube intercondenser and aftercondenser.

The condensers are responsible for removing all steam utilized by the steam jets and exhausting the non-condensable load from the vessel source.

The condensers are thermally guaranteed and mechanically guaranteed per ASME Code Section VIII, Division 1 and TEMA C, Type BEM (Connect Heads & Fixed Tubes) requirements. Other TEMA classes, types and codes are available upon request.

All condensers are designed utilizing a fouling factor of 0.001 on both the shell and tube side of the condenser. Cooling water temperature is set at 100°F and maximum pressure drops are 10 psia on the tube side and 0.1 psia on the shell side. Larger fouling factors and various cooling water temperatures can be accommodated upon request. System condensers are designed to utilize cooling water in series with inlet to the intercondensers and discharge from the aftercondenser.


When starting a turbine, it is desirable to reduce the condenser pressure from atmospheric to a lower pressure quickly.

This can be accomplished by utilizing a hogger ejector. The capacity of the hogging ejector is dependent upon the effectiveness of the turbine gland seals, the volume of the condenser shell and the turbine casing, as well as the time desired for a specific pressure reduction.

Hogging jets use large quantities of steam; but are only in operation for startup. When a desired vacuum is achieved, the hogger is shut off and the staged jet system starts. The hoggers typically do not discharge to a condenser and are normally supplied with a silencer.

All S&K steam jets:

  • Are individually performance tested;
  • Designed with pressure & vacuum taps, for convenient data collection;
  • Air designed for stable operation down to zero suction flow;
  • Mechanically designed to 150 psig at 365°F per the guidelines of the ASME Code (higher pressure and temperature ratings can be designed upon request).  The base unit operating steam pressure is 115 psig at dry and saturated conditions.  Minimal system change is encountered if superheated steam or steam pressure other than 115 psig is required.
  • The extraction of a mixture of water vapor and air from an air cooled condenser in a power plant.
  • Geothermal applications.
  • Large capacity systems applicable to the chemical, petrochemical, petroleum, pharmaceutical, food processing, and metal refining industries.