When processing any kind of remotely viscous food product, it is inevitable that a certain amount will adhere to surfaces, such as the inside of vessels and pipe work, or be left in equipment after processing. The potential value of this lost product can add up, especially when handling large quantities of viscous, valuable products such as honey, syrups and purées.
Globally, an estimated 30 percent of the food produced for human consumption is lost or wasted somewhere in the supply chain1. Approximately 185 million tons of food is lost and wasted in North America each year, and of this some 57 million tons are lost in the United States between harvest and the consumer2. At a time when all forms of food waste is under increasing scrutiny, it is important that all parts of the food chain are as efficient as possible when it comes to wastage.
The good news is that the processing and packaging part of the food chain is already efficient, accounting for just four percent of overall food losses according to the UN Food and Agriculture Organization (FAO)3. However, there is always room for improvement and management processes and equipment design are two tools food manufactures have at their disposal.
There are two ways of minimizing such losses in equipment, and in an ideal situation they will be used in combination. The first involves designing equipment, such as tubular heat exchangers, which prevent product adhering to the surface in the first place – keeping it flowing through the system. The second aspect is the use of dedicated systems to clean and recover product from equipment after processing, and before full cleaning occurs.
Many modern heat exchangers are designed to handle viscous fluids without fouling. Some of these units use the corrugated tube designs, while other units used in more demanding situations use scrapers to continually remove residues from the surface of the tubes before they build up. These heat exchangers can be used for numerous processes, including heating and cooling, cooking, concentrating, pasteurizing and sterilizing.
This self-cleaning provides two advantages. First, as the foodstuff being treated is kept moving and does not adhere to the tube surface, losses during processing are minimized. Secondly, because a ‘fouling layer’ is not built up, the optimal thermal performance of the heat exchanger is maintained, which increases process efficiency and reduces energy use or treatment times.
No matter how good your equipment is at preventing product build-up, there will come a time when cleaning, usually in the form of cleaning-in-place (CIP), needs to happen. Depending on the range of products handled and product complexity, this may be required several times a day. If product remaining in equipment is ‘flushed’ through as part of cleaning procedures then hundreds of thousands of pounds of product could be lost each year.
Traditionally the problem has been overcome by the use of ‘pigging systems’ to physically push product through key parts of the system or to use water or air to push product through/ All have certain disadvantages, including added complexity and the potential to dilute or contaminate products.
Another option is to use a heat exchanger that is capable of emptying itself of produce before the cleaning cycle commences. This range of tube-in-tube heat exchangers uses a scraper bar within each inner tube to enhance product flow, prevent fouling and minimizing pressure drop. A unique feature of the HRS R Series is that the scraper bar features a helical screw which rotates at high speed. When configured correctly, this screw can be run in reverse, effectively emptying the heat exchanger tubes of product without damaging it or changing its characteristics.
Due to the amount of product saved, and the fact that it is often unnecessary to install additional product recovery systems, these heat exchangers can quickly pay for themselves. In the long term, this can be a more economic option than alternative systems which have lower capital costs.
Located in Phoenix and Atlanta, HRS Heat Exchangers is an industry leader in thermal technology and heat transfer solutions. The company specializes in the design and manufacture of tubular, corrugated and scraped surface heat exchangers.
1 Global Initiative on Food Loss and Waste Reduction (2015) https://www.fao.org/3/i4068e/i4068e.pdf
2 Food Loss and Waste in North America http://www.cec.org/files/documents/publications/11772-characterization-and-management-food-loss-and-waste-in-north-america-en.pdf
3 Reducing Food Loss and Waste. World Resources Institute Working Paper. http://www.unep.org/pdf/WRI-UNEP_Reducing_Food_Loss_and_Waste.pdf