Evaporation

Evaporation is a widely used technique for concentration of fluids. By removal of fluid as vapour, the concentration of dry solid will increase in the remaining fluid. Normally the fluid is water. However, the technique can be applied to most fluids.

The reasons for application of evaporation can be:

  • The product should have a high concentration of dry solid
  • The quality and stability of the product can be improved by removal of water
  • Reduction in the volume of the fluid will reduce the cost of transportation and storage
  • Removal of water will reduce the cost of waste handling
  • Concentration of dry solid for reuse
  • Recycling of purified fluid can be obtained by condensation of the vapour

Evaporation can be applied to most fluids, e.g.:

  • Food articles as milk, fruit juice extracts, fish proteins
  • Chemical fluids
  • Process and waste water
  • Mineral slurries

Previously, evaporation was an energy demanding process. However, by implementation of modern technology the energy consumption has been drastically reduced. Today, the evaporators can be operated 24 hours a day, without continuous monitoring. In addition, the maintenance costs are very low. The evaporation plants can be designed with a minimum of installation time and with minor adjustment of the building structure.

Specification of the correct evaporation method is determined by the characteristics of the fluid, the production volume, space available, energy cost etc. EPCON is a supplier of both falling film and flash evaporators.


Falling film evaporator
This evaporator consists of vertical heating tubes where the liquid is boiling as it falls down as a film inside the tubes. Falling film evaporators are compact facilities with very low energy consumption. They are particularly suitable for fluids that to a minimal extent will form precipitates on the tube walls.

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Flash evaporator
The flash evaporator is suitable for fluids with a high viscosity and where deposition of solid material in the evaporator could be a problem. The fluid is heated and introduced into a chamber, which is kept at a lower pressure than the corresponding saturation pressure of the heated water. Upon entering the chamber, a portion of the heated water will immediately boil or “flash” into vapour.

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Flash cooler
If the fluid mixture is hot, a flash cooler can be applied to lower the temperature. This process will in addition provide a small increase in the concentration of dry solid. The flash cooler is particularly suitable for viscous or sensitive fluids where a high content of dry solid is required.

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Energy supply
Efficient energy utilisation is an important factor in evaporation. The energy supply for the boiling process can be by:

  • Direct steam
  • Recompression of exhaust steam /MVR, TVR)
  • Surplus energy from other processes

Correct selection of energy supply is very often decisive in obtaining a cost efficient evaporation process.
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EPCON is a company with several years of experience as a supplier of evaporators. We have developed high theoretical and practical competence within specification of technology and equipment. This competence is based on detailed knowledge about fluid properties. This is of outmost importance in the design of evaporation plants. To ensure optimal solutions, we carry out analyses and tests on fluids in our test laboratory. The test results and conclusions form the basis for the individual design of each installation.

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