Has been used a little for demonstration.

QUASITURBINE ROTARY STEAM ENGINE
Up to 1.5 kW (2 HP) UNDER 60 PSI
Pre-commercial unit for Applications test, Research and Demonstration.

High torque, low rpm, 36 cu. in. (600 cc) displacement per revolution.
Idle at 100 rpm with only a few psi.
No significant vibration compared to piston.
Shaft bearing are not pressure sealed.
External housing is 8 inches in diameter, shaft is 3/4 inch.

New technology, pre-commercial series.
Manufacturer: Under license by QT Tronconneuses in Montréal Canada.
Guarantee: One year free pick-up of defective replacement part.
Run-in: Recommended 4 hours of run-in time under compressed air.
Lubrication: Use conventional ISO460 oil.
Pressure flow energy conversion efficiency: 
Up to 80 % - (Not total system efficiency)
See manufacturer's website
(They also manufacture a 12 kW - 16 hp).

Up to 60 psi (4 bar) peak (max. 150 C; 300 F) for over 1 kW at 500 rpm.
Exhaust hose not included.