Evaporation Technology

Evaporation Technology Evaporation plants are used as a thermal separation technology, for the concentration or separation of liquid solutions, velopment work spanning many decades, and the experience of A liquid concentrate that can still be pumped is generally the several thousand installed refer- desired final product. Evaporation may however also aim ences, GEA Wiegand continues to at separating the volatile constituents, or distillate, as would provide the broadest technical ex- be the case in a solvent separation system. During these pro- pertise and the respected ability cesses, it is...

Reference Products from GEA Wiegand Evaporation Plants The following list shows groups of products Chemical and Pharmaceutical Industries that are successfully concentrated in more than 4.000 GEA Wiegand evaporation plants. Caustic solutions Caustic soda solution, caustic potash solution Additional products are detailed in our refe- Organic acids Ascorbic acid, citric acid rence lists. Inorganic acids Phosphoric acid, nitric acid Saline solutions Ammonium nitrate, ammonium sulphate, sodium sulphate Urea, diethyl amine Methanol, ethanol, glycerine, glycol, isopropanol Organic products Aromatic...

Evaporator Types FALLING FILM EVAPORATORS Design Vertical shell-and-tube heat exchanger, with laterally or concentrically arranged centrifugal separator. Operation The liquid to be concentrated is supplied to the top of the heating tubes and distributed in such a way as to flow down the inside of the tube walls as a thin film. The liquid film starts to boil due to the external heating of the tubes and is partially evaporated as a result. The downward flow, caused initially by gravity, is enhanced by the parallel, downward flow of the vapour formed. Residual film liquid and vapour is separated...

that will lead to incrustation and the build-up of deposits. For complete wetting it is important that a suitable distribution system is selected for the head of the evaporator. Wetting rates are increased by using longer heating tubes, dividing the evaporator into several compartments or by recirculating the product. Particular features Best product quality – due to gentle evaporation, mostly under vacuum, and extremely short residence times in the evaporator. High energy efficiency – due to multiple-effect arrangement or heating by thermal or mechanical vapour recompressor, based upon the lowest...

Evaporator Types FORCED CIRCULATION EVAPORATORS Design Horizontal or vertical shell-and-tube heat exchanger or plate heat exchanger as the calandria, with flash vessel/separator arranged above the calandria, circulation pump. Flash vessel/separator Heating steam Concentrate Condensate

Operation The liquid is circulated through the calandria by means of a circulation pump, where it is superheated at an elevated pressure, higher than its normal boiling pressure. Upon entering the separator, the pressure in the liquid is rapidly reduced resulting in some of the liquid being flashed, or rapidly boiled off. Since liquid circulation is maintained, the flow velocity in the tubes and the liquid temperature can be controlled to suit the product requirements independently of the pre-selected temperature difference. Particular features Long operating periods – boiling/evaporation does...

Evaporator Types PLATE EVAPORATORS Design Plate heat exchanger, separator. A plate-and-frame configuration employs special plates, with alternate product and heating channels. The plates are sealed by gaskets located within specially designed slots that do not require adhesives. These gaskets can be inserted and removed without special tools. Vapour Main separator Pre-separator Plate calandria Heating steam

Particular features Product and heating media are transferred in counterflow Use of different heating media – due to plate geometries, through their relevant passages. Defined plate distances in con- the system can be heated with both hot water as well as with junction with special plate shapes generate strong turbulence, resulting in optimum heat transfer. High product quality – due to especially gentle and uniform Intensive heat transfer causes the product to boil while the evaporation during single-pass operation. vapour formed drives the residual liquid, as a rising film, into Little space...

Evaporator Types CIRCULATION EVAPORATORS Particular features content of the evaporator is very low due to the relatively short Vertical shell-and-tube heat exchanger of length and small diameter of the heating tubes (1- 3 m). Quick start-up and large specific capacity – the liquid short tube length, with lateral separator arranged at the top. Fields of application For the evaporation of products insensitive to high temperatures, where large evaporation ratios are required. For products which have a high tendency to foul and for non-Newtonian products, where the apparent viscosity may be The liquid...

Special Evaporator Types FLUIDISIED BED EVAPORATORS FALLING FILM, SHORT PATH EVAPORATORS Design Vertical fluidised bed heat exchanger (on the tube side solid particles such as glass Vertical shell-and-tube heat exchanger or ceramic beads, or stainless steel wire equipped with concentrically arranged particles are entrained in the liquid), condenser tubes within the heating tubes flash/vessel separator and circulation and integrated separator in the lower part Operation Operation The liquid is evenly distributed over the heating tubes by Same principle as for the forced circulation evaporator....

Special Evaporator Types RISING FILM EVAPORATORS COUNTERFLOW-TRICKLE EVAPORATORS Design Vertical shell-and-tube heat exchanger with top-mounted vapour separator. Shell-and-tube heat exchanger, lower part of calandria larger than that of e.g. the rising film evaporator, top-mounted separator equipped with integrated liquid distribution system. Operation The liquid to be concentrated is supplied to the bottom and rises to the top in accordance with to the “mammoth pump” principle, or rising film principle. Due to external heating, the liquid film starts to boil on the inside walls of the tubes...