FOOD & BEVERAGE
egg; separated egg (whites or yolks); or a treated product, like salted yolk. Each type of product presents a different challenge in terms of viscosity, and products with added salt also introduce a higher likelihood of equipment degradation or corrosion.
Pasteurisation can have a number of unwanted effects, including gel formation and softening of the yolk, or irreversible denaturation of the proteins and changes to the appearance. If not handled correctly, thermal pasteurisation can decrease protein content, change physical characteristics such as texture and colour, and increase product viscosity. Choosing the right pasteurisation regime and equipment is therefore vital to minimise and prevent such unwanted effects.
LIMITATIONS OF PLATE AND SMOOTH-TUBE HEAT EXCHANGERS
In the past, many processors have used plate heat exchangers to pasteurise egg products, but these allow product to coagulate on the plate surface, fouling the heat exchanger so that frequent cleaning-in-place (CIP) is required to maintain operational efficiency. This adds time, energy and cost to the processing, and also reduces overall capacity.
Tubular heat exchangers overcome some of these problems (for example, the larger diameter helps the product to run through the heat exchanger more easily) but there can be issues around heat transfer efficiency and the necessary size of the exchanger to achieve effective pasteurisation.
WHY CHOOSE CORRUGATED HEAT EXCHANGERS?
Fortunately, all of these issues can be overcome with the use of corrugated tube technology as employed by HRS, which uses turbulent flow to reduce fouling. Because a corrugated tube has an increased heat transfer rate compared to a smooth tube of the same length, the heat exchanger can be made smaller.
It is also important that the equipment chosen allows regular inspection and suitable CIP. Not only do HRS corrugated tube heat exchangers facilitate this, but because their design helps to prevent fouling in the first place, they also reduce downtime. Therefore, the operational run times between cleaning cycles are generally much longer with corrugated tubes than smooth ones, further increasing the overall efficiency of the process.
CORRUGATED TUBE HEAT EXCHANGERS Using HRS’ corrugated tube technology, both heat transfer and efficiency are increased over standard smooth tube heat exchangers. In addition, potential fouling is minimised, making it possible to supply more compact and economical heat exchangers. HRS offers a wide product range, with models developed for various types of industries, manufactured from stainless steel. Bespoke designs and other materials are also available.
Advantages of Corrugated Heat Exchangers: • Increased heat transfer • Minimal fouling • Reduced servicing costs • Compact design
HRS offers three types of corrugated tube heat exchangers: • Annular Space Heat Exchangers • Double Tube Heat Exchangers • Multitube Heat Exchangers
SCRAPED SURFACE HEAT EXCHANGERS For difficult heat transfer applications, with high viscosities and where fouling can become a problem, the preferred option is a scraped surface heat exchanger. The reciprocating or rotating movement of the scrapers mixes the fluid whilst cleaning the heat exchange surface. This keeps heat transfer high and reduces downtime. In addition, an increase in the turbulence increases the level of heat transfer.
HRS offers two technologies for scraped surface heat transfer: Unicus series which reciprocates and R series which rotates. Both of these patented solutions are designed for specific needs.
PLATE HEAT EXCHANGERS HRS plate heat exchangers are ideal for applications where the fluids have relatively low viscosity with no particles. They are also an ideal choice where product outlet temperature is close to the service inlet temperature.
HRS Heat Exchangers
www.hrs-heatexchangers.com
FACTORY&HANDLINGSOLUTIONS | DECEMBER/JANUARY 2021 23
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