Integrally Geared Compressors – Reliable, Proven Technology

Integrally Geared Compressors

From its invention in 1948, Siemens has perfected the design and manufacture of integrally geared compressors. Today, more than 2,200 units have been installed globally proving their worth with a wide reference base in a wide range of industries and process applications.

Product Information

Integrally geared compressors

Integrally geared compressors are multi-shaft machines. Several pinion shafts with two impellers each are arranged around a central bull gear. For each pinion shaft a perfect combination of shaft speed and impeller size can be realized. All impellers are of overhung design and can be fitted with adjustable inlet guide vanes in front of each impeller. Inter-stage cooling of the gas stream can be done after each impeller discharge. The combination of these features allows for high volume flows, outstanding energy efficiency even under part load, all in a compact design.


For small- to medium-size compressor sizes, Siemens offers a package design. The package includes the compressor, driver, process gas coolers, lube oil console, process piping, and all tubing and wiring. The package design leads to significantly reduced on-site installation time. For large-size units all main train components are delivered separately on site and installation is on a concrete foundation.


Customized Design

Customized compressors

Our customized line of integrally geared machines can accommodate up to four pinion shafts with up to eight impellers total resulting in impressive pressure ratios which can be achieved in a compact design. Compressors can be designed according to API 617 or API 672 and customer specifications. Driver options depend on process and energy resources and can be electric motor, steam turbine or gas turbine and are suitable for direct turbine-drive or integrated turbine design.

Customized compressors with integrated radial expansion turbine

A variant of the customized integrally geared compressor allows the integration of a single- or two-stage radial expansion turbine as a direct drive option for the compressor. This allows the direct recovery and conversion of energy from pressurized high temperature process gas streams into kinetic energy driving the compressor. Depending on the amount of available energy this drive option can serve as a sole, main or auxiliary driver in combination with e.g. an electric motor or motor generator.


  • All gear components designed and manufactured within our own supply chain
  • High efficiency and outstanding operating range
  • Axial inlet impellers for high volume flow
  • Multi-service capability 
  • Up to eight impellers / stages
  • Four-shaft gear for cost sensitive motor driven trains
  • Inter-cooling between stages
  • Design options for any kind of gas
  • Designed according to API 617, API 672 and customer specifications
  • Comprehensive driver options

Technical data

  • Volume flow rates up to 1,000,000 m³/h / 590,000 cfm
  • Discharge pressure up to 200 bar / 2,900 psi 
  • Gear box ratings up to 65,000 kW / 87,000 hp


  • Air separation
  • Fertilizer
  • Synthetic fibers (PTA, DMT, Caprolactam)
  • Metallurgy
  • Refining
  • Petrochemicals
  • Carbon capture and storage
  • Compressed air energy storage (CAES)
  • Fuel gas
Standardized Design

Standardized Compressors

Our standardized designs come with up to two pinion shafts with two impellers each. Standardized integrally machines come in two groups of frame sizes.

The first group is available in nine frames (sizes 10-100) and offers a wide range of options and can be packaged as compact single-lift units. The product line is the compact and standardized version of the customized integrally geared compressor series, the trusty workhorse of the air separation and process industries. Its high degree of standardization results in lower capital cost and shorter delivery times as compared with fully customized compressors.

The second group extends the available range of volume flow rates to between 120,000–400,000m3/h capacities with additional five frame sizes (165-400). Eighty percent of the machine is pre-engineered for consistency and repeatability. 20 percent of the machine can be customized for specific customer process needs.

Frame sizes 10 - 100


  • Compact, single-lift unit
  • Maximum performance due to predesigned gears, highest efficiency impellers, tailored aerodynamics, and predefined auxiliaries
  • Up to four impellers

Technical data

  • Flow rates from 3,600 to 120,000 m³/h (2,120 to 70,680 cfm)
  • Pressure ratio up to 20
  • Electric motor drive (fixed speed)


  • Air separation
  • Plant air
  • Nitrogen

Frame sizes 165 - 400


  • Efficiencies are comparable with customized series by use of same well proven flow components
  • High flexibility derived from large number of fixed options

Technical data

  • Flow rates from 120,000 to 400,000 m³/h (70,680 to 235,600 cfm)
  • Pressure ratio up to 6.5
  • Electric motor drive (fixed speed)


  • Air separation (main air compressor)
Gearless Compressor

Single Stage Centrifugal Compressor

Our single stage centrifugal compressor is the perfect fit for atmospheric air compression at low pressure ratios. It covers a large flow range from small to very high volumes of up to 1.000.000 m3/h. This compressor uses well proven components from our integral geared compressor line and is designed in accordance with API 617. State-of-the-art aerodynamic parts allow a compact, single stage design. If necessary, an external gear box is used to match the driver speed. This modular design offers the advantage of an unchanged compressor design irrespective whether the machine is driven by a steam turbine, gas turbine or electric motor.


Our single stage overhung compressor boasts a simple and robust design with well referenced components, smaller dimensions and less weight at the highest efficiency level, and low maintenance requirements.

In case of higher pressure ratio requirements, the configuration comprises two single stage overhung machines driven by a double-ended steam turbine drive between the compressors. 


  • Large flow range
  • Simple, robust design in accordance with API 617
  • High efficiency
  • Highest reliability due to well referenced components
  • Low service intensity
  • Easy maintenance
  • Small dimensions
  • Low weights
  • Low spare part costs

Technical data

  • Volume flow rates up to 1,000,000 m³/h / 590,000 cfm
  • Pressure ratio up to ~3 (up to ~6.5 in case of 2 units)
  • Suitable for electric motor, steam turbine or gas turbine drive 


  • Regeneration air applications in PDH (Propane DeHydrogenation) plants
  • Blast furnace blowers (2 units)
  • Fluid Catalytic Cracking (2 units)
  • Main Air Compressor for Air Separation units (2 units)

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