MARIETTA, Ga. — Heat exchangers are widely used in beverage manufacture and processing for materials including purees and smoothies, coffee extract, juices and yeast-malt extracts. As well as basic heating and cooling, they are used for other processes including pasteurization, sterilization and evaporation, where many of these more complex products cause issues for simple plate and tubular heat exchangers. One way to overcome the challenges presented by complex mixtures, particulates or viscous fluids is to use a scraped surface heat exchanger, such as the patented HRS Unicus Series.
The Unicus from HRS Heat Exchangers has been specifically designed to provide unrivalled heat transfer with a wide range of difficult beverage products including fruit and vegetable smoothies, syrups, juices and extracts including coffee and malt. The products have a high fouling potential (therefore limiting heat transfer), but at the same time need delicate handling to preserve fragile product integrity. A process of continual improvement means that Unicus heat exchangers are available with a wide range of scraper types, providing even more choice for applications from cooling to sterilizing and everything in between.
The Unicus Series, which is ideal for hygienic applications, is based on traditional shell and tube heat exchangers, with the addition of a patented stainless steel scraping mechanism which is hydraulically moved back and forth within each interior tube. This movement performs two key functions. Firstly, it minimizes potential fouling of the product by keeping the tube wall clean. Secondly, the movement creates turbulence within the material. Both of these actions help to increase heat transfer rates and together, they create a highly efficient heat transfer process ideal for viscous and high fouling materials.
Another benefit is the fact that the separate hydraulic action means that the speed of the scrapers (which are available in a number of different designs) is highly controllable and can be optimized for the product being processed. This means that materials which may be susceptible to shear stress or pressure damage, such as thick juices and smoothies, can be handled gently to prevent such damage while still providing high levels of heat transfer.
Matt Hale, International Sales & Marketing Director at HRS Heat Exchangers, comments: “The HRS Unicus series has proved particularly useful in handling viscous food and drink products where texture and consistency are important attributes. For example some juices may shear when subjected to too much pressure, making them unusable. The Unicus means that effective heat transfer can be carried out at low pressure overcoming such problems.”
Each Unicus heat exchanger consists of three elements: a hydraulic cylinder and power pack, a separation chamber to ensure hygiene and preserve product separation from the motor, and the heat exchanger itself. In smaller units a pneumatic cylinder can be supplied instead of a hydraulic unit. The heat exchanger consists of a number of tubes (depending on the specification), each of which contains a stainless steel rod to which the appropriate scraping elements are fitted. Using a range of food-safe materials including Teflon and PEEK (Polyarylethe-retherketone), these provide different internal geometry setups according to the application; such as 120o scrapers for large particulates and 360o scrapers for viscous fluids without particulates.
The Unicus Series is scalable according to need, simply by increasing the shell diameter and adding more interior tubes as required, from one tube up to 80. A key feature of the unit is the specially designed seals which separate the inner tube from the separation chamber. With the exact seal design depending on the product application, this prevents leakage of the product and ensures internal and external hygiene. A standard range of models for food and beverage processing provide heat transfer areas from 0.7 to 10 m2, while larger models up to 120 m2 can be made according to specific requirements.
The prevention of fouling can be particularly important for evaporation applications, so HRS Heat Exchangers have developed a special version of the Unicus for evaporation systems where volume reduction is vital. The scraping action keeps the heat transfer surfaces clean, meaning that Unicus evaporators can concentrate materials to a level beyond that typically achieved with traditional technologies. The Unicus evaporators can be used in either multi-effect setup or in combination with mechanical vapor recompression.
“Not only does the scraping action improve heat transfer, but it also allows continuous operation in many situations, increasing plant productivity,” adds Matt. “Over many years we have developed the design of the Unicus so that we have versions and specifications that are particularly suitable for beverage applications.”
About HRS Heat Exchangers
Headquartered in the UK, HRS Heat Exchangers Ltd operates at the forefront of thermal technology, offering innovative and effective heat transfer solutions worldwide, across a diverse range of industries. With over 35 years’ experience, we specialize in the design and manufacture of an extensive range of tubular, corrugated and scraped surface heat exchangers. All our products comply with the ASME standard. HRS has a network of offices throughout the world: Spain, USA, Malaysia, Australia and India; with manufacturing plants in the UK, India and Spain.