HEAT TRANSFER FEATURE Manufacturers in highly regulated


industries such as food and pharmaceuticals cannot overlook the importance of maintenance in times of pressure, particularly when working with heat transfer fluids. Once a thermal oil enters a heat transfer system, the manufacturer can no longer see its condition — so might not notice issues until they impact production. Inefficient heat transfer caused by


degradation of thermal oil can lead to poor quality products, from inconsistent cooking of food to improper blending of ingredients for tablets. If manufacturers cannot prove that the product is safe, entire batches of product must be thrown out. Manufacturers using thermal fluids should consider how to manage its degradation to adhere to regulations, minimise risk and maintain productivity. The reason that these problems can


DON’T NEGLECT MAINTENANCE IN TIMES OF PRESSURE


Clive Jones, managing director of Global Heat Transfer, explores the importance of maintenance in these times of increased pressure, and outlines the risks of neglecting maintenance tasks


T


he current Coronavirus outbreak has led to increased pressure on the food


industry. For example, a penchant for lockdown baking means that grocery sales of flour increased in the UK by 92 per cent. This caused smaller mills, such as one in Oxfordshire, to begin running at 24-hour operations for the first time in its 125-year history. When under pressure to upscale production, manufacturers cannot forget the importance of good practice, particularly in highly regulated industries. Food, beverage and pharmaceutical


manufacturers are under growing pressure to continue delivering high-quality products in reaction to customer


behaviour. As well as stockpiling, disruption is causing shortages that will impact critical industries. For example, demand for gas in the US has dropped, leading to manufacturers also reducing the production of ethanol and its by-product — CO2. Without CO2 supply, beverage manufacturers have to pay more for the gas to continue beer and soda production. In times of changing demand,


manufacturers operating with skeleton staff may postpone less important processes to increase production. However, neglecting any process that can negatively impact quality or safety can lead to costly and wasteful recalls.


ACCURATE TEMPERING SPEEDS UP CHOCOLATE MAKING


Tempering, or the controlled heating and cooling, of chocolate is an essential step in the manufacturing process and has traditionally been carried out in batches, with many companies still using traditional methods. However, one forward-thinking UK chocolate supplier has introduced a new system for tempering its chocolate, based on the HRS R Series of scraped surface heat exchangers. Tempering chocolate is necessary to produce consistently small crystals of cocoa butter when it is heated


and cooled. Without this strict temperature control, the chocolate will ‘bloom,’ having a matt appearance and waxy texture, and often white patches where the cocoa fat has separated. Without tempering it is impossible to get the characteristic ‘snap’ and glossy finish. The client processes chocolate from a number of suppliers which is generally delivered in bulk. Historically


the tempering process was carried out by hand using traditional methods. They had also tried tempering the chocolate in specialist vessels, but it was still quite a slow process. Following successful trials, the client worked with HRS to develop a solution which could be mounted on a


process skid. This comprises three HRS R Series rotary scraped surface heat exchangers in series; the first raises the temperature by 19°C, the second cools it back down by 2°C, before the final heat exchanger raises the temperature to a level allowing the chocolate to be transported and worked elsewhere in the factory. The heat exchangers have speeded up the tempering process, increasing the volume of product the factory can handle. The R Series features a patented helical scraper bar design which prevents the build-up of viscous products,


such as molten chocolate, on the tube surface to maintain efficient heat transfer. The scrapers also help to mix the product in the tube, improving the homogeneity and effectiveness of heat transfer. HRS Heat Exchangers


www.hrs-heatexchangers.com / PROCESS&CONTROL


Maintenance is important because once a thermal oil enters a heat transfer system, the manufacturer can no longer see its condition — so might not notice issues until they impact production


occur is that over time, the molecules in a thermal fluid will break down by a process called thermal cracking, which creates volatile light-ends and heavy-ends. The build-up of light end components is a potential fire risk because they decrease the ignition temperature of the heat transfer fluid. The accumulation of heavy- ends results in the formation of sticky carbon deposits or sludge, which reduces the efficiency of the system and may cause it to break down. Regular heat transfer fluid sampling is


the best way to ensure that thermal oil will not negatively impact production. Engineers should take samples when the thermal fluid is hot and circulating to ensure it is an accurate representation of fluid condition inside the system. Engineers should then send the sample


to a reputable thermal fluid specialist for analysis. The specialist will conduct tests to measure parameters such as flash point temperature, carbon levels and total acid number (TAN). A final report will show findings on the oil’s condition and provide recommendations on how to maintain thermal fluid efficiency. Regular sampling gives engineers the insight needed to anticipate fluid lifespan and mitigate degradation, optimising system productivity, reducing the risk to safety of employees, and avoiding downtime. All manufacturers, from the small


Oxfordshire mill to large US beverage manufacturers must respond to changes in demand to continue stocking shelves during this time of disruption. Manufacturers also have a responsibility to keep staff and production as safe and efficient as possible to supply high-quality and safe products to the market, so maintenance must remain a priority.


Global Heat Transfer www.globalhtf.com


PROCESS & CONTROL | JULY/AUGUST 2020 15


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