Boiling Point Elevation
also known as BPE
Dissolved salts lower the vapour pressure of a solution, so it boils at a higher temperature than pure water at the same pressure. The difference, the boiling point elevation, grows with salt concentration and reaches several degrees in saturated brines. It effectively reduces the temperature difference available for heat transfer in an evaporator.
Why it matters in practice
Boiling point elevation silently consumes driving force. A three-effect train designed on water properties can lose a meaningful share of its available temperature difference to BPE in the later, more concentrated effects — which is why later effects must be sized generously.
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Reference entry GL-BOILING-POINT-ELEVATION. Definitions on this page describe engineering practice in hydrometallurgical process design; they are not a substitute for test work on your own material.