Tag Archives: concentration

Freeze Concentration – Equipment Series

A while back I wrote about pressure processing which was driven by the “fresher flavour” of juice that is not heated. Freeze concentration is driven by the same quality concerns and is an alternative to concentration by boiling off water. 

IFT Web Article on FReeze Concentrationclick the image to visit the website 

This article from the Institute of Food Technologists covers freeze concentration in a few pages giving information on the process and discussing the advantages and disadvantages of the technology 

 
Interesting is that the energy needed to melt a kg of ice is several times lower than that required to evaporate a kg of water. In these days of high energy costs and carbon footprints this would seem to be an advantage. However, the freeze concentrator can not be run in mutiple effect plants which allows an evaporator with sufficient effects to use almost the same energy. 

 
Even more disadvantageous, is that the freeze concentrator is often unable to reach the concentration required and a thermal evaporator has to be used as a finisher. 

 

Falling Film Evaporator – Equipment Series

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click image to visit GEA Process Engineering site

 

In falling film evaporators the liquid product (A) usually enters the evaporator at the head (1) of the evaporator. In the head the product is evenly distributed into the heating tubes. A thin film enters the heating tube are it flows downwards at boiling temperature and is partially evaporated. In most cases steam (D) is used for heating the evaporator. The product and the vapor both flow downwards in a parallel flow. This gravity-induced downward movement is increasingly augmented by the co-current vapor flow. The separation of the concentrated product (C) form its vapor (B) is undergoing in the lower part of the heat exchanger (3) and the separator (5).

Falling Film Evaporator – Equipment Series

Falling Film Evaporators are designed for the production of concentrates from heat sensitive liquids.

 

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from: GEA-Wiegand
(click image for full story online)

 

The text on the above image from a Wiegand brochure reads:

FALLING FILM EVAPORATORS

Design
Vertical shell-and-tube heat exchanger, with laterally or con- centrically 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 in the lower part of the calandria and in the downstream centrifugal droplet separator. It is essential that the entire film heating surface, es- pecially in the lower regions, be evenly and sufficiently wetted with liquid. Where this is not the case, dry spots will result

 

Tomato Cultivation and Processing – Free Online Technical Manual

Another document available for free from The ACP-EU Technical Centre for Agricultural and Rural Cooperation (CTA) through Anancy.

 

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from: Anancy
(click image for full story online)

 

This uninspiring cover hides the value of the information and misleads on it breadth – it covers processing and business issues in 16 pages of concise and clear information.

The information covers post harvest handling, quality, hygiene, drying, heat treatment, concentration, pulping and pasting. It includes a very interesting process for the large scale production of paste using muslin bag filtration.