A desuperheater is a device that cools superheated steam to a temperature close to its saturation temperature, ususally by spraying atomised droplets of water into the flow of supeheated steam. Superheated steam is steam that is at a temperature above its saturation temperature.
Desuperheating of steam is an almost universal feature of a sugar factory. This is for two reasons
There are numerous methods of desuperhing steam each with their own advantages and disadvantages: a good discussion on the various approaches to desuperheating is given by Spirax Sarco
A heat and mass balance over the desupeheater yield two equations
ms2hs2 = ms1hs1 + mwhw
ms2 = ms1 + mw
Combining these yields
mw = ms1 · (hs1 - hs2) / (hs2 - hw)