Impulse-Type, Two-Phase Cryogenic Expander

Allows for the expansion of liquefied gases into two-phase mixtures.

Based on proven impulse turbine blade technology, our impulse-type, two-phase cryogenic expander allows for the expansion of liquefied gases into two-phase mixtures. Harnessing the energy of two-phase expansion increases the expander’s generator output, reduces boil-off losses, and improves the overall liquefaction and cooling processes.

This cryogenic expander has optimized staging to minimize axial load at the radial ball bearings and tolerates a high content of vapor mass. Custom-designed, it is offered for liquefaction and refrigeration processes with relatively high vaporization capability in cryogenic hydrocarbon applications. The isentropic efficiency of these units is estimated at around 60% to 70%, depending on the mass flow rate and unit pressure drop.

These expanders do not require a Joule Thomson (JT) valve at the downstream as compared to a Francis-type expander. Impulse-type, two-phase cryogenic expanders have generator nameplate ratings ranging from 300 kW to 2.2 MW for a single unit. If the process requires high-flow output, these units can be installed and operated in parallel configuration. In addition, they can be retrofitted to existing LNG liquefaction and cooling applications.


Impulse-Type Two-Phase Expander with CalloutsOther Features
  • Achieves same pressure drop as expansion valve (JT valve)
  • Flashing expander that can handle high volumes of vapor formation (vapor mass fraction > 0.3)
  • Axial flow impulse design with reduced overhung design and stage reaction
  • Vertically suspended upward flow configuration
  • Single-shaft compact design with submerged generator
  • Cryogenic radial ball bearings with high contact angle to overcome axial load
  • Cooling and balance lines to adjust pressure and flow to efficiently cool submerged generator and lubricate ball bearings
  • Variable speed operation to optimize the work transfer and performance based on process requirements

Impulse-Type Two-Phase Expander Diagram