Evaporators

  • Evaporators are a common process whenever large amounts of water or another solvent are to be separated from relatively non-volatile components.
  • They function by simply boiling the volatile component away.
  • They are often seen when large amounts of fresh water are required. For example, drinking water on ships or for steam ship boilers ( top product).
  • Evaporators are also used to concentrate aqueous solutions such as fruit juice or orange juice (bottom product).
  • They are common when the process fluid contains precipitates that need to be crystallised.
Advert for evaporators (circa 1900).
  • When designing your evaporator, you start with a feed stream, and you have to achieve an output specification.
  • For example, you have a feed stream of 1000 kg/hr of orange juice with a solids concentration of 7.08 w/w.
  • You need to concentrate it to 50 w/w solids content before it is economical to ship it overseas.
  • How big should our exchanger be to achieve this? What is the heat transfer area required? What utilities (steam) will be used? What is the overall duty of the evaporator?
Evaporators