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Thermodynamics/Multiple Effect Evaporator


Hi, I'm stuck on a problem I was given to work through as preparation for an exam I have in a week and was hoping you might be able to help me.  I've drawn the flowchart and written out all the information we were given but I'm stuck on what to do about the temperatures of the concentrate.

I know the concentrate would cool after some of the water evaporated but can't work out how I would find the exact temperature since I wasn't given the mass flow of the steam. Would it be wrong to assume that once the water evaporated after the first and second effect that the temperature would return to the original temperature of the feed which was 20'C?

Thanks a million in advance

Hi Vienna,

No I think not. The best solution would be to look up the boiling point of water at the pressures indicated for both the first and second evaporators. They must achieve this temperature to get evaporation and as the liquid is boiling this temperature cannot be exceeded.

I hope this helps.
Best wishes



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Thermodynamics, chemistry, chemical reactions, kinetics, chemical reaction safety, dust explosion technology, static electricity. General science.


Over 40 years experience as a practicing thermochemist in industry. Head of the fire and explosion laboratory of a major European chemical company (Ciba-Geigy). Now retired.

Institute of Chemical Engineers. Royal Society of Chemistry.

Chartered Chemist, Member of the Royal Society of Chemistry (C.Chem MRSC). Msc Sheffield.

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