The plate evaporator version chillers with most rapidly gaining popularity. It is a relic of plate and frame heat exchanger, which was used in the food industry for many decades. Plate and frame heat exchanger consists of a set of plates, which are gasketed so that, when these plates are bolted together one of the liquid flows between two plates, and other liquids between pairs of adjacent plates. Corrugated plates with a herringbone pattern that physically strengthens plates, and also contributes to the turbulence of the fluid, providing excellent convection heat transfer coefficients. This type of heat exchanger is attractive for such branches of food industry, as dairies, because at the end of the working shift bolts of fastening of plates in a position can be relaxed, allowing access to any surface cleaning. 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.
Operation Product and heating media are transferred in counterflow through their relevant passages. Defined plate distances in conjunction with special plate shapes generate strong turbulence, resulting in optimum heat transfer. Intensive heat transfer causes the product to boil while the vapor formed drives the residual liquid, as a rising film, into the vapor duct of the plate package. Residual liquid and vapors are separated in the downstream centrifugal separator. The wide inlet duct and the upward movement ensure optimum distribution over the total cross-section of the heat exchanger.
Use of different heating media – due to plate geometries, the system can be heated with both hot water as well as with steam.
High product quality – due to especially gentle and uniform evaporation during single-pass operation.
Little space required – due to compact design, short connecting lines and small overall height of max. 4 - 6 m.
Easy installation requiring little time – due to pre-assembled, transportable construction units.
Flexible evaporation rates – by adding or removing plates.
Ease of maintenance and cleaning – as plate packages can be easily opened.
Fields of application
For low to medium evaporation rates.
For liquids containing only small amounts of undissolved solids and with no tendency to fouling.
For temperature-sensitive products, for highly viscous products or extreme evaporation conditions, a product circulation design is chosen.