In steam-using industries, two commonly referred to types of steam are dry steam (also called
Saturated steam) and wet steam.
Dry steam applies to steam when all its water molecules remain in the gaseous state. It's a transparent gas.
Wet steam applies to steam when a portion of its water molecules have given up their energy (latent heat) and condense to form tiny water droplets. Take the example of kettle boiling water. Water is first heated using an element. As water absorbs more and more heat from the element, its molecules become more agitated and it starts to boil. Once enough energy is absorbed, part of the water vaporizes, which can represent an increase as much as 1600X in molecular volume.
In a boiler, energy from the fuel is transferred to liquid water in order to create steam. At first, cold water gets warmer and receives energy in the form of “sensible heat”, right until the boiling point.