To the untrained eye, steam comes in one form. It’s the stuff that you see after a
summer rain, or the annoying liquid-turned-gas that fogs up the mirror. But there’s
more to steam, and knowing the differences between the types is key to taking full
advantage of their properties.
Today, we’ll take a look at the similarities and differences between saturated and
superheated steam, including how and why they are used in applications.
Turn Up the Heat
The basics behind steam are simple: when water is heated, it will be vaporized into
steam. During this vaporization process, the steam changes from a liquid phase into a gas phase that can be used and controlled in many industrial processes.
But, it is when the temperature is increased (by an independent 'super heater') that the saturated steam becomes superheated steam. In short, superheated steam’s name is
exactly what it is: saturated steam that’s had its temperature significantly raised.
It is important to note, however, that the moment that saturated steam becomes
superheated steam is dependent on the steam’s pressure and temperature. That means that once the steam is heated over its boiling point for that specific pressure, it will become
A Place for Each
With the versatility of steam, it’s no surprise that saturated steam has a variety of use
cases. Primarily, saturated steam’s big advantage is its adaptability to temperature
changes through pressure. The temperature of saturated steam is directly related
to its pressure, meaning that controlling it is as easy as increasing or decreasing the pressure. By contrast, the temperature of superheated steam is not related to its pressure.
Additionally, saturated steam’s ability for even heating throughout allows for a more
useful and usable product. An application example of putting saturated steam to use
can be found here:
Electronic Temperature Control of Saturated Steam
Superheated steam is not as ubiquitous, but still has an important use case: turbines.
Since superheated steam won’t form into droplets at its high temperature, it can keep
its machinery dry, saving them from becoming water damaged. This is incredibly
important, as any damage to turbines can be catastrophic to both the process and the
cost of the machine.
For other applications, superheated steam falls flat because of its high expense to
produce, requiring costly machines to create the right temperature. Additionally, its
temperature isn’t as easy to maintain with pressure as saturated steam, posing a difficult
challenge to its users.
Burling Valve is capable of working with saturated steam across multiple applications
and pressures, including up to 450ºF and 400 PSI.