Main benefits
  • Modular hydraulics for high efficiency in a wide range of operating conditions as required for gas-fired combined-cycle power plants
  • Optimized design for thermal conditions as applicable in gas-fired combined-cycle power plants
  • Centerline mounted with large branch sizes for optimized inlet flow, low noise level, and higher allowable forces and moments
  • Unaffected by rapid temperature variations and therewith highly suitable for gas-fired combined-cycle power plants where frequent start-stop operation is specified
  • Stiff shaft design for critical speeds above the maximum operating speed
  • Multiple screws mechanical tensioners are used on large sizes to allow simpler tightening and loosening
Main applications

The MD pumps are suitable for pumping clean or slightly polluted, hot or cold water. They have been specifically designed for application such as:

  • Main boiler feedwater pump in captive, independent, biomass, and industrial power plants
  • Main feedwater pump in gas-fired combined-cycle and concentrated solar power plants
  • Start-up boiler feedwater pump in utility thermal power plants
  • High-pressure water pump in general industry
Features and benefits
Cutaway of MD
1. Casing support

Centerline mounting absorbs high forces and moments. Pre-warming not required

2. Impeller
  • Several hydraulic sets per pump size guarantee high efficiencies and low operating costs over a wide operating range
  •  Low Net Positive Suction Head Required (NPSHR) first stage; double suction first stage can be provided for selected sizes
3. Shaft

 Transmits the required torque and minimizes deflection

4. Rotor design

 Stacked rotor with staggered keyways to transmit torque

5. Intermediate take-off

 Reduces head losses; large take-off flow is available on certain sizes

6. Hydraulic thrust balancing system
  • Balance drum and axial thrust bearing designed for long life under extreme operating conditions
  • Balance disc and lift-off device (mechanical and magnetic) available for frequent start-stop operation
7. Bearings and lubrication
  • Sleeve radial and tilting pad thrust bearings are optional for high power and thrust duties
  • External lube oil supply can be provided for high power and thrust duties
8. Discharge casing and nuts
  • Mechanical tensioners allow simple tightening and loosening and provide high security against loosening (no special tooling required)
  • High-pressure version available up to 350 bar MAWP (5'080 psi) and able to accept downward thermal transients
Operating data
50 Hz 60 Hz
Discharge sizes up to 200 mm up to 8 in
Capacities up to 1,200 m3/h up to 5,300 US gpm
Heads up to 2,800 m up to 9,200 ft
Suction pressures up to 50 bar up to 725 psi
Discharge pressures up to 350 bar up to 5,080 psi
Temperatures up to 210°C* up to 410°F*
Performance range
MD performance range 50 Hz
Performance range 50 Hz
MD performance range 60 Hz
Performance range 60 Hz
Pump part Material
Suction stage and discharge casings Chrome steel
Impellers Chrome steel
Shaft Chrome steel
Balancing system Chrome steel
  • Boiler feed pump (BFP) for biomass waste
    Boiler feed pumps for biomass firing power plants applications are typically small/medium ring section type. Axially split multistage pumps are also available when required. The pump size and the design pressure will depend very much of type and the output of the power plant.

  • Boiler feed water and booster pumps
    Feed water pumps (FWP) pump the feed water from the de-aerator through the HP heaters to the boiler. The major characteristic of FWP is their high differential head.

  • Feed water pump (FWP) for gas-fired
    Feed water pumps (FWP) pump the feed water from the de-aerator through the HP heaters to the heat recovery steam generator. The major characteristic of the FWP is their high differential head. In all sizes of gas-fired combined-cycle power plants, the FWP are horizontal ring section type; occasionally, they could also be barrel or axially split type.

  • Feed water pumps for solar power generation
    Feed water pumps (FWP) pump feed water from the de-aerator through the HP heaters to the solar steam generator. The major characteristic of FWP is their high differential head. The FWP are usually horizontal ring section type, but depending on customer requirements, they can also be barrel or axially split type.

  • Power plants
    Sulzer’s extensive product portfolio to maximize the performance and reliability of your solid organic fuel biomass power plant, solid industrial or municipal waste fuel biomass power plant, and liquid or gaseous organic fuel biomass power plant processes.
Optional designs
MD balance drum
Balance drum
Balance drum

The balance drum device carries the major proportion of the hydraulic thrust. The drum diameters are chosen to minimize the thrust at normal operating point. The residual and additional thrust loads occurring above/below the normal operating point are carried by the thrust bearing, typically a tilting pad.

The balance drum is suitable for:

  • Pumps operating at the end of the curve, up to 120% of the best efficiency point
  • Frequent start-stop applications thanks to nearly wear-free device
MC & MD high pressure pump balance disc
Balance disc
Balance disc

With a balance disc, the axial force is completely compensated; no axial thrust bearing is required. Due to the smaller balancing leakage flow, total efficiency of the pump is higher than the pump efficiency with the balance drum design.

For pumps with frequent start-stop operations, the installation of a mechanical or magnetic (PERMAVORTM) lift-off device is recommended.

Mechanical or magnetic (PERMAVORTM) lift-off devices


  • Prevent touching and wear of disc/counter disc operation at low speed such as start-up and shut-down
  • Self-controlling passive systems
  • Reduce load on balance disc under normal operation
  • Offer long service life
MD high pressure pump (up to 350 bar)
MD high pressure pump (up to 350 bar)
High pressure design
  • Design pressure (MAWP) up to 350 bar
  • Extended flow and head range meet the requirements of the steam-water cycle for the latest heavy-duty high-output gas turbine developments
  • Advanced design to accommodate steep thermal transient conditions (upwards and downwards)
Case studies
  • Case studies
    Wherever fluids are pumped, mixed, controlled or applied, we are there. See how our solutions create value for customers and learn how we can make your pumping and mixing processes more efficient and profitable, safeguarding your production and ensuring lasting reliability.

  • Matching feedwater pump designs with advances in gas fired power plants
    As the global demand for electrical energy continues to grow, more power plants are being built and their designs have to accommodate the changing requirements of the power generation market. Gas turbine manufacturers have developed larger and more efficient units, which need to be supported by advanced feedwater pumps (FWP) to ensure long-term reliability as well as cost-effectiveness. Sulzer's pumps offer industry-leading availability with a robust construction and very low maintenance requirements.
Contact us