Why Plate Heat Exchangers with special design can operate as perfect Condensers / Evaporators

Once upon the time Plate and Frame HE's were considered beautiful tools in Heat Transfer only when high DP's were available.

How can get low pressure inside flow channels if pressing depth was so narrow? It was impossible to think about a falling film evaporator with plates...

                                                                                       

Shell & Tube HE's in vertical arrangement have been for years traditional set up and later on surface dimpled plate HE's

But in the late 1980's  plate evaporator as result of development work done in collaboration with beet sugar manufacturers started to be used. This new type of cost-effective rising film evaporator rapidly became a success in the beet sugar industry and has subsequently spread to many other applications

AlfaVap uses the cassette concept with the plates welded in pairs. The heating steam is condensed in the welded channels while the evaporated product passes through the gasketed channels.

The Concitherm Series provides particularly high performance in rising film plate evaporators often found in the sugar processing industry. They can also be used as boosters in combination with conventional tube-type evaporators. The optimised plate structure of the Concitherm Series makes it possible to have wide gaps with no contact points over up to 3 m2 of heat transfer area. At the same time these PHEs offer a convincing 100 % higher transfer compared to conventional shell-and-tube heat exchangers.

SIGMASTAR® forms strong pseudo “tubes”.Combines mechanical rigidity with excellent low shear heat transfer geometry. Even product distribution to all “tubes” due to communicting tubes effect.The superior distribution eliminates dead flow areas and hot spots.

Basically special design of these PFHE's is focused on low pressure drop and large amount of volumes of vapours, so that corrugation is partially "flat type" to create geometry of flow channels similar to small tubes.

Modern plates with special design have been produced recently:  SWC136 Sondex condenser is specially developed for condensing of low pressure vapour.

The plate is designed as a semi-welded cassette, with a welded channel for the condensing side. On the medium side there is a traditional plate heat exchanger gasket. The unique plate design makes it possible to utilize almost the whole plate area as heat transmission area. This plate is designed in two different plate patterns on the welded side. For dirty and fibre products, the plate is designed with a wide gap plate pattern. For clean products the plate pattern is on both the welded side as well as the medium side a herring bone pattern. The plate has a combination of two different plate patterns heights. This makes it optimal for keeping a low pressure drop on the welded side and at the same time a high turbulence on the medium side. This results in a high heat transmission U value

                               

  

The DN800/32” vapour connection makes it possible to cover many duties in a single pass solution. All connections will thus be on the head of the heat exchanger, which is of big advantage during service work. The plate pattern and inlet area are also designed for CIP cleaning making the service of the PHE easy.

PFHE can be used, as mentioned, also as Rising Film Evaporator. The SEC174 Sondex plate evaporator is a specially developed unit for evaporation duties.

The plate is designed as a semi-welded cassette, with a welded channel for the medium side, and on the evaporation side there is a traditional plate heat exchanger gasket. The unique plate design ensures an even distribution of the product over the whole plate making optimal rising film evaporation. The special designed plate pattern ensures a high turbulence of the fluids on both sides, resulting in a high heat transmission co-efficient.This results in a very compact heat exchanger with a small hold-up volume.

The unique evaporator and condenser plates from Sondex are especially designed for condensing low temperatures, vapour and for multistage evaporation of highly concentrated products.
The unique asymmetric large port holes ensures an optimal exploitation of the available heat transfer area. The unique inlet design and high thermal efficiency is what makes these plates the most efficient in the market today.

 

Therefore if you have to design  unique evaporator and condenser plates especially designed for condensing low temperatures, vapour and for multistage evaporation of highly concentrated products start to consider PFHE's special design as valide alternative to S&T HE's or Tube in Tube HE's...