Product-to-product tubular heat exchangers: surprisingly versatile
Many people involved in food and beverage processing are not aware of just how versatile product-to-product (P2P) tubular heat exchangers are. But just some of the products currently being processed in this equipment are UHT milk, chocolate and flavoured milk, cream, drinking yoghurt, juices with or without fibres, nectars, soups, coffee and tea.
In fact, Tetra Pak has 8,000 different food products in its database and a large number of them can be used in product-to-product tubular heat exchangers. Everything from low- to medium-viscosity products are suitable. The exceptions are few: thick products such as fruit concentrates, purees, custards, sauces, puddings and spoonable yoghurts.
In contrast, plate heat exchangers are actually limited when it comes to handling products with fibres and particles because of the narrow channels between the plates. This is where tubular heat exchangers come into their own. The product flows more easily and the diameter of the tubes can be dimensioned according to the product.
Longer time between cleaning
Tubular designs also come into their own in dairies for processing UHT milk. A plate heat exchanger processing milk at temperatures of up to 137-140°C usually has to be cleaned after about ten hours due to fouling. In comparison, a tubular heat exchanger (including product-to-product designs) can go on working for up to 40 hours before it needs cleaning.
Plant-based beverages that are fortified with protein can also cause similar fouling due to the protein precipitating out of the liquid as a solid. Here again, a tubular heat exchanger is a good choice if you want to maximize production time. Indeed, this type of heat exchanger is becoming more and more popular for plant-based beverages.
Ordinary pasteurized milk is not subject to the same high temperatures as UHT milk, and has different demands for cleaning. Tubular heat exchangers can also be used here except when processing at very high capacities of more than 60,000 litres per hour.
Though product-to-product heat transfer has been a familiar concept in plate heat exchangers since the 1950s, the use of product-to-product regeneration in tubular heat exchangers is still relatively new. Food manufacturers often do not know just how versatile this tubular application is.
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