Superheated steam is steam at a temperature higher than water's boiling point. If saturated steam is heated at constant pressure, its temperature will also remain constant as the steam quality (think dryness) increases toward 100% Dry Saturated Steam. Continued heat input will then generate superheated steam. This will occur if saturated steam contacts a surface with a higher temperature. The steam is then described as superheated by the number of degrees it has been heated above saturation temperature.
Superheated steam and liquid water cannot coexist under thermodynamic equilibrium, as any additional heat simply evaporates more water and the steam will become saturated steam. However this restriction may be violated temporarily in dynamic (non-equilibrium) situations. To produce superheated steam in a power plant or for processes (such as drying paper) the saturated steam drawn from a boiler is passed through a separate heating device (a 'super heater') which transfers additional heat to the steam by contact or by radiation.
Superheated steam is not suitable for sterilization. This is because the superheated steam is dry. Dry steam must reach much higher temperatures and the... Read More