Questions about MVR evaporators
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Does the secondary steam (saturated steam) coming out of the separation chamber of the MVR evaporator become superheated steam after passing through the compressor? If so, how can it be turned into saturated steam? Is it water? So the amount of compressed raw steam is greater than the amount of secondary steam?
The amount of saturated steam after adding quench water is indeed greater than the amount of raw steam drawn out by the compressor from the evaporator, and it is also greater than the amount of steam generated by evaporation in the evaporator.
So how can we determine the amount of secondary steam that becomes raw steam after compression, and then the amount of raw steam that turns into saturated condensate through heat exchange?
I’ve seen that MVR evaporators require continuous addition of fresh water! I haven’t thought carefully about the specific principle! Write it down and come back to study it later*
The compressed steam is supersaturated; water injection is used to remove the supersaturation
Then how is the amount of compressed saturated steam calculated, and how is the amount of condensate water after passing through the heating chamber calculated?
In a vertical forced-circulation MVR evaporation system, are the temperatures of the liquid entering the circulation system and those of the liquid leaving the circulation system below the boiling point?
In MVR systems, the temperature difference between the material entering and leaving the forced circulation is kept relatively low (within 2 degrees), which is determined by the low effective heat transfer temperature difference. There is also a benefit to this: forced-circulation heaters basically do not form scum at the outlet! The heat exchanger, which has been in use for two years, still appears very smooth when opened.
Answer to the original poster: Since the steam entering the compressor is saturated steam, it will become superheated upon compression, regardless of how much the temperature rises (by 6–20°). As for the amount of water sprayed, it is determined by the superheat, which is the increase in the enthalpy of the steam at the outlet relative to that at the inlet; this value corresponds to the temperature rise during compression. This difference can be eliminated by spraying water, causing it to vaporize into steam, thereby reducing the superheat.