In-Line Turboexpanders

for Gas Pressure Reduction and Clean Power Generation

The FreeSpin™ In-line Turboexpander (FIT) provides a way to capture the energy lost in pressure reduction. Turboexpander systems with Calnetix’s Magnaforce™ motor generators extract kinetic energy from the pressure reduction at the various stages of gas processing and distribution and allow for the generation of electricity with no added pollution.

The FIT system consists of an integrated high-speed turbine and high-efficiency generator that runs on magnetic bearings in a hermetically sealed, lubrication-free unit to provide more efficient and reliable performance. The company offers standard or custom-engineered turboexpanders to meet customer requirements in any industry for applications, such as air separation, natural gas pressure letdown, geothermal power recovery, steam pressure letdown, gas liquification and distribution, chemicals and petrochemicals and gas turbine power recovery.


For more than a decade, Calnetix has been at the forefront of turboexpander technology, designing, implementing and manufacturing some of the most innovative solutions for expanders across many industries. The unique advantages of Calnetix’s FreeSpin™ system include the following:

Proven Fuel-free Power Generation 

Calnetix’s FreeSpin™ In-line Turboexpander uses zero fuel and produces zero emissions, so there are no contaminants that could seep into the production process.

The simplicity of the FIT design enables a cost-effective solution for power generation. The average payback on a system is approximately one to two years, depending on the wholesale price of electricity. Calnetix’s turboexpander technology, utilized in industrial waste heat recovery systems, has accumulated millions of operating hours through its over 400 fielded units.

Hermetically Sealed Module


The FreeSpin™ In-line Turboexpander runs on magnetic bearings and is hermetically sealed into a single unit, eliminating the need for a gearbox and a lubrication system. It does not require dynamic seals, which often cause environmental hazards upon failure.


High-speed Permanent Magnet Generator


The high-speed permanent magnet motor generator used in Calnetix’s turboexpander is simply constructed and operates with very little losses, which translates into low cost of ownership. FIT’s highly efficient motor generator has variable speed and load capabilities and provides a greater power density and a smaller footprint than conventional systems. The Calnetix turboexpander produces power up to 125 kW at a continuous speed of 25,000 rpm and provides a system efficiency above 95 percent. Higher power models are available as well.


Reliable Active Magnetic Bearings


While maintaining a similar cost structure to conventional oil lubricated bearing systems, the Powerflux™ active magnetic bearings in FreeSpin™ systems eliminate physical contact between rotating and stationary components, as well as eliminate lubrication, lubrication systems and seals, which provide users with the following benefits:

  • Higher reliability

  • Lower maintenance

  • Longer lifespan

How In-Line Turboexpanders™ Work

The FreeSpin™ In-line Turboexpander (FIT) provides a way to capture the energy lost in pressure reduction. This is how they work.

The Process

The Process

  1. The pre-heated high-pressure gas flows into the turboexpander
  2. The gas expands through the radial turbine wheel
  3. The low-pressure gas exits the FIT and is ready for delivery to residential and commercial users
  4. The energy wasted during the pressure reduction process is recovered by the FIT and converted to electrical power
  5. Any excess high-pressure gas not directed through the FIT is expanded by the conventional pressure regulator
  6. The produced electricity enters the Vericylce™ Bi-directional Power Electronics Unit, which can be programmed to specific power requirements
How In-Line Turboexpanders Work