Dear all,
Why does scaling occur at boiling? (can we say that the maximum concentration increase at surface at boiling so scaling occurs?)
If boiling does not occur, Does we have scaling at the surface of heat exchangers?
Regards
Most salts become more soluble in water at higher temperatures,e.g., it is easier to dissolve NaCl salt in hot water than in cold water .However, there are salts "that are called reverse soluble salts such as calcium sulfate & calcium carbonate" which behave in an opposite way. For such salts, as temperature increases, their solubility decreases in water. When one heats a water stream containing these calcium-based salts, the salts begin to deposit on the heat exchange surface. Once this happens, the heat transfer performance of the heat exchanger will decrease rapidly until there is coating of the entire surface of the heat exchanger or what is described as "scaling". For most calcium-based salts, this scaling effect starts at around 60 °C and gets worse at higher temperatures.
Agree with the answer provided by Dr. Matar, Scales are formed by the use of hard water in the heat exchangers and boilers. Thus, for such applications it is always advised to treat the water (to minimise the hardness) before using it.
Very true. There is another reason also. Undissolved solids in the minute size (colloidal form) stick to tube surface due to friction and are also contributor of scaling in many heat exchangers.
Perfect,
Thanks all,
Could you please answer my following question if you know?
https://www.researchgate.net/post/When_does_scaling_occur
Thanks
Dear Steffen Schmid
https://www.sciencedirect.com/science/article/pii/S0032591006004980
Regards
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