Prud'Hon Capus boiler

The Prud'Hon Capus boiler tried to improve the poor water circulation in the common Scotch fire-tube boilers by adding water tubes in a dry-back combustion chamber.
It was claimed that this modification made the Prud'Hon Capus boiler 10 per cent more efficient than conventional Scotch fire tube marine boilers.
The Prud'Hon Capus as well as the Howden-Johnson boilers failed to make an impact despite of these advantages, the disadvantages of the hybrid arrangement being greater than the advantages.

The red coil, to the right of the
convection water-tubes, is the superheater.

A Prud'Hon Capus marine steam boiler with the common dry-back combustion chamber open for service.
Two fire-tubes and some of the convection water-tubes are visible on this picture.

Thirty-two Prud'Hon Capus boilers were installed onboard the cruise liner Ile de France in 1927. The operation pressure was 16 bar.
The swedish steamer Soya Lovisa was equipped with two Prud'Hon Capus boilers in 1954.