In distillation columns, heat is supplied to the bottom in order to vaporize one or more substances from a mixture of substances. The vapors dissipate heat in the head . Since the vapor has a lower dew point than the boiling point of the sump due to its different composition , the heat drawn off at the top of the column cannot be used directly to heat the sump. With vapor compression, the vapor is compressed without the addition of heat. As a result, the temperature rises above the boiling point in the sump, so that the vapor can be used to heat the sump.
Vapor compression is only used if no cheap superheated steam is available for heating the column sump. Either mechanical vapor compression or thermal vapor compression can be used. With mechanical vapor compression, the vapor is compressed with the aid of a compressor , which is an additional part of the system that must be operated with electrical energy. In thermal vapor compression, the vapor is brought to the higher temperature with the aid of steam and a jet compressor before it is fed back into the distillation column.
- Dairy : Evaporation of milk and whey for milk powder production
- Sugar production : The process is used in the multi-stage evaporator station. The vapor from the last evaporator stage is thermally compressed with the aid of higher-quality motive steam from an intermediate extraction of the factory steam turbine and fed to the first evaporator stage.
- Salt production : Mechanical vapor compression can be used to evaporate the brine.
- Sewage treatment plant : evaporation of sewage sludge
- Chemical industry : Evaporation of aqueous process solutions
A first patent for a system with heating by vapor compression was filed by Peter von Rittinger in Austria in 1853. The patent was issued for a system for salt production that used a reciprocating compressor to compress the vapor. The compressor should be driven by a water wheel . In 1856 a test facility based on the Rittinger patent was set up in the Ebensee saltworks , but it only worked with pure water and failed to operate with brine because a coating (fouling) formed on the heat exchanger . The tests were therefore stopped in 1858 without the facility being able to be used commercially.
In 1876, the Swiss Paul Piccard built a salt production plant with vapor compression and a heat exchanger equipped with a mechanical peeling tool to remove fouling. Such a system was successfully put into commercial operation in the Bex saltworks in 1878 and is considered the first really functioning system with vapor compression. The compressor resembled a steam engine powered by a water wheel. The system known as the Piccard apparatus or Weibel-Piccard evaporator could crystallize 175 kg of table salt per hour.
Piccard was able to sell further systems that were made by a predecessor company of Ateliers Piccard-Pictet & Cie. were manufactured. In 1881 one was installed in the Ebensee saltworks, one in Maixe near Nancy in 1885 and later four in Salies-du-Salat in France, as well as one in Bad Salzelmen in Germany. Further systems were built for the production of condensed and powdered milk and installed in Switzerland and France. In 1882 the first plant for evaporating sugar molasses was delivered to the beet sugar factory in Pohrlitz , Czech Republic , where it was put into operation in 1885.
- GEA Wiegand GmbH (Ed.): Evaporation technology with mechanical vapor compression . ( gea-wiegand.de [PDF; 960 kB ]).
- Biography Ritter von Rittinger, Peter. Austria Forum, accessed on May 25, 2015 .
- Martin Zogg: History of the heat pump . Swiss contributions and international milestones. Ed .: DETEC . 2008, ISBN 978-3-03302154-9 , pp. 17–19 ( pulledg-engineering.ch [PDF; 8.5 MB ]).
- Un industriel au cœur de l'Europe: lettres à sa famille, 1857-1886 . Editions d'en bas, 2008, ISBN 978-2-8290-0356-1 ( Google Books [accessed May 16, 2015]).