What Is Superheated Steam?

Production

• Superheated steam production begins in a boiler, where water is heated up to 100 degrees Celsius, giving off saturated steam. The vapor then passes through a heated coil of copper tubing, a second heat exchanger, or a separate super heater unit, which brings the saturated steam's temperature beyond the boiling point. This must be performed separately, as adding more heat to the boiler would simply result in the further evaporation of water. After superheating, the steam contains enough energy to ignite a match.

Properties

• Because superheated steam production entails the further heating of saturated steam, all traces of moisture would have then vanished, leaving behind dry steam. It contains more energy than saturated steam but much less useful heat content. Superheated steam has about the same heat transfer coefficient as air, making it an insulator and a poor conductor of heat. It is therefore rarely used as a heat transfer medium, as it does not cool down easily to yield its energy.

Power Generation

• Because of its unique properties, superheated steam finds its most important application in power generation, where it is used nearly exclusively to run turbines. Its dryness makes it ideal for this purpose maintenance-wise, as any water droplets present in the steam would unbalance and break the vanes. Unlike saturated steam, superheated steam will not condense even after losing some of its energy to the turbine rotor. Superheated steam therefore improves the turbine's overall thermal efficiency.

Other Applications

• Aside from being an ideal energy source for power generation, superheated steam finds further use in several other industrial applications such as drying, stripping and cleaning. It is widely used in large-scale epoxy drying, catalyst film production, steam oxidation, surface drying and different nanotechnology applications. Superheated steam is also used to power steam locomotives, again being the more powerful and economical alternative to saturated steam in that it gives the engine a higher thermal efficiency and contains little or no moisture.