superheater

noun

1. A component of a boiler system that heats the steam above its saturation temperature to prevent it condensing, and in the case of a steam engine to improve its efficiency.

   “In addition to all this, the fluidity of the steam itself was much increased by high superheat, usually achieved by means of the Houlet superheater. […] When the engine is working hard, the temperature of the steam is usually raised by the superheater to about 750° F.”