Design, Build and Field Trial of Steam Expander-Generator (SLDE)


A global industrial engineering group required a system utilising energy waste produced during steam pressure reduction, otherwise dissipated into the environment, to exploit a unique market opportunity.


In 2016 D&T developed a 50kW steam let-down turbo-expander (SLDE). It was designed to operate in parallel with a pressure reducing valve.

This unit was a back-pressure expander producing 50kW electrical power from the expansion of steam from a saturated or superheated state with pressure up to 14barg at the inlet.

It consists of a highly efficient radial turbine directly connected to a permanent magnet generator suspended on gas bearings. It converts exergy of the steam into electrical at significantly higher efficiency than competing technologies.


The turbo-expander was extensively tested and completed a 1000-hour client site endurance test followed by more than 8000 hours of operation in an industrial environment connected to an end user’s factory steam grid with no maintenance and zero blade erosion at the end of the operational tests. The project was subsequently cancelled when TPG D&T was dissolved.

Architecture Single stage, permanent magnet motor with gas bearings
Process media Steam
Inlet temperature Saturated/ Superheated
Inlet pressure 7-14barg
Outlet pressure 1-4barg
Rated power 50kW(net)
Rotational speed 70,000rpm

Note: TPG D&T business was dissolved in 2017. Its core Technical Team, who pioneered this project formed C2 Technology, to continue D&T’s business of developing innovative technologies for energy industry.

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