Effect of Steam Superheat

            You would think superheating steam would always increase the usefulness of the steam. This is not always true. A few examples:
 

·         Steam superheat is bad for amine reboilers. The superheated steam increases the shell side tube temperature and accelerates H₂S corrosion.

·         Steam superheat is bad for jets. The superheated steam increases the volumetric flow through the steam nozzle, and thus reduces the height flow of steam.

·         Steam superheat is neutral for reboilers in general. The LMTD is not increased by using superheated steam. It’s the saturation temperature which determines the LMTD.

·         Steam superheat is slightly helpful when stripping a product. But the effect is so minor that I typically ignore superheat in my steam stripper calculations.

 

The real value of superheating steam is the guarantee that it is dry. Dry steam is critical for steam strippers, jets, and turbines.