Twister® Supersonic Separator

How it works

The Twister® Supersonic Separator has thermodynamics similar to a turbo-expander, combining the following process steps in a compact, tubular device:

  • expansion
  • cyclonic gas/liquid separation
  • re-compression

Whereas a turbo-expander transforms pressure to shaft power, Twister achieves a similar temperature drop by transforming pressure to kinetic energy (i.e. supersonic velocity):

  • Multiple inlet guide vanes generate a high vorticity, concentric swirl (up to 500,000g)
  • A Laval nozzle is used to expand the saturated feed gas to supersonic velocity, which results in a low temperature and pressure.
  • This results in the formation of a mist of water and hydrocarbon condensation droplets.
  • The high vorticity swirl centrifuges the droplets to the wall.
  • The liquids are split from the gas using a cyclonic separator.
  • The separated streams are slowed down in separate diffusers, typically recovering 70 – 75% of the initial pressure.
  • The liquid stream contains slip-gas, which will be removed in a compact liquid de-gassing vessel and recombined with the dry gas stream.

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Figure 1 shows a cross-section of a Twister tube with typical process conditions.

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Figure 2 compares the thermodynamics of Twister with conventional Joule-Thomson expansion. In this example, the same feed conditions (100 bar/1450 psi, 40°C/104°F) and the same pressure drop (30%) has been assumed for both processes.