HEAT TRANSFER PERFECTING JUICE PROCESSING
Matt Hale, international sales and marketing director at HRS Heat Exchangers, outlines the company’s complete juice processing solution, from raw material through to finished product
maximise the quality of the finished product, attention to detail is needed at every stage: from de-packing the raw material through to pasteurisation, and on to the final aseptic packing process.
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With almost 40 years’ experience in providing packing and processing solutions for fruit juice manufacturers, HRS Heat Exchangers is able to offer a complete processing solution from raw material to finished product. This not only includes thermal treatment for pasteurisation/ sterilisation, but also all the necessary equipment to handle the product from raw material to finished pack.
While fruit juice concentrate is often delivered in bulk containers, juice for the production of high quality not-from- concentrate (NFC) is usually supplied in frozen form to maintain quality and freshness. This frozen unconcentrated juice is often supplied in lined 200 litre drums. While the drums themselves are convenient and easy to handle, the frozen concentrate requires breaking up and warming before it can be processed further and packaged. The HRS I Series offers options to de-pack and crush (the IC Series) and melt (IM Series) this frozen juice (a process also sometimes known as re-melting) ready for storage or further processing. The IC Series features a roller conveyor which feeds individual drums into a tipper that empties them into the crusher. Here, a specially designed spiked roller crushes the solid ice into an icy slush, which is then transferred to the IM Series re-melting device. Based on HRS’s tubular heat exchanger
technology, the IM Series raises the temperature of the juice from frozen to around 4 deg. C. in 90 seconds. From here, the cold liquid juice can be pumped to a holding tank, or straight into the next process step.
12 FEBRUARY 2021 | PROCESS & CONTROL
rocessing fruit and juice concentrates into finished bottled drinks is relatively straightforward, but in order to
Capable of handling up to 60 drums (12,000 litres) per hour, the HRS I Series uses a number of existing HRS heat exchanger technologies (including HRS DTA Double Tube and HRS MI Multitube heat exchangers) together with an ice crusher to re-melt both large and small chunks of ice, providing optimal rates of heat transfer and energy efficiency.
One remelted, HRS can supply holding tanks of any required size, from 2,500 to 50,000 litres made to client’s bespoke specifications.
High Temperature Short Time (HTST) pasteurisation, also known as ‘flash pasteurisation’, is the preferred technique for making premium quality juice. The HRS series of MI/MR pasteurisers uses a food-grade,
the corrugated tube technique, HRS’s pasteurisation systems use water at a lower temperature to reduce the risk of product damage. Another benefit of higher heat transfer rate is that the system footprint can be reduced using shorter heat exchanger pipes. The shorter length of the heat exchanger also results in a reduction in pressure drop, which saves pumping power and reduces energy costs – often by 40%.
The corrugated design/profile of the inner tube helps reduce product fouling – it disrupts the fluid boundary layer and creates higher velocity and turbulence. As the juice travels around the system, it is less likely to stick to
multi-tube corrugated tube heat
exchanger to speed up the heat transfer, while the corrugated tubes create extra turbulence in the juice as it flows through. This extra turbulence means that the juice can be heated up to pasteurisation temperature much quicker – typically up to 30% faster. This is important as the longer the heating process, the greater the deterioration in product quality. The temperature of the heating media can also affect quality – the hotter the heating media, the more damage the tubes inside the heat exchanger pasteuriser will cause to the product.
Because of the high heat transfer rates of
the tube wall and cause corrosion and reduction in performance (which could lead to increased downtime and maintenance costs, expensive parts and reduced system lifespan).
Due to the use of a counter-current design to pump juice and heating and cooling water around the exchanger, the maximum heat transfer rates achievable by the system are also improved, making HRS MI/MR Series pasteurisers suitable for the thermal treatment of fresh and from-concentrate fruit and vegetable juices.
The smooth and economical pumping of the juice through the system is another important consideration. The HRS BP Series is a purpose-designed, hydraulically operated, reciprocating, positive-displacement pump, with an expanding cavity on the suction side
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