Grocery store milk aisle

Heat exchangers have long been a vital tool for pasteurization, sterilization, and other food processing needs. And while the technology is mature, there’s still plenty of innovation happening.

To learn more about it, we talked with Melissa Fryer, an engineer with 20 years’ experience and a food industry veteran who’s currently a manager for the food and beverage market at Kelvion, Inc.

Fryer describes Kelvion as “a new brand in heat exchange.” But she emphasizes that it’s only the brand and name that’s new. Kelvion was formerly the heat transfer arm of GEA and was divested in October 2014, with the new brand launching in November 2015. Despite the new name, “we’ve been doing heat exchangers for many, many years,” Fryer says. In fact, the company got its start in 1920.

While Kelvion provides a variety of heat transfer equipment across all markets — food and beverage, chemical, marine, industrial, oil and gas, and so on — Fryer’s focus is on the food industry. We talked with her about current challenges and opportunities facing processors, including:

  • Maximizing run times
  • Promoting cleanability
  • Keeping up with food trends
  • New heat exchanger technologies

Heat exchangers in the food industry

First, a bit of background. Simply speaking, a heat exchanger is a device used to transfer heat between two or more fluids. In the food and beverage industry, heat exchangers are often used to reduce or eliminate microbials, thereby making products safe for consumption and extending their shelf life. A heat exchanger may also be used to heat or cool products prior to filling, drying, concentration, or other processes.

Certain heat exchanger designs are better suited to products with certain attributes. Qualities like viscosity and particle size can help determine which type of exchanger is best for any given need.

While several types of heat exchangers are used in the food industry, Fryer says that the most common are plate heat exchangers. “Plate heat exchangers have been around for a long time,” she says. “They’re one of the most efficient methods of heat transfer for fluid products.”

On a basic level, plate exchangers consist of multiple plates installed inside a frame. Fluid passes through the plates, allowing for heat transfer from the hot to the cold side. Fryer explains that plate heat exchangers must provide a sufficient velocity across the plate to effectively transfer heat while also controlling pressure drops.

Plate heat exchangers are all based on the same general principles. But they can be customized for different users and functions. “We have standard models,” Fryer says, “but how the plates are arranged into those models is different for every application.”

She notes that well-designed plate heat exchangers can help meet three of the industry’s biggest challenges: maximizing run times, promoting cleanability, and keeping up with food trends.

Maximizing run times

Fryer says some of her customers’ biggest concerns have to do with run times. She often hears the question, “how can we get the longest possible run out of our heat exchanger?” The issue is especially significant in the dairy market, where products with high protein content tend to foul exchangers more easily.

According to Fryer, the answer to the run time challenge is in sizing and design. Proper sizing of a heat exchanger ensures the longest possible run. And when it comes to design, a good one can make all the difference. An even flow across the plates, for instance, helps to maximize operation time.

Fryer believes that current run times attained by the best equipment may not get much longer. “I think we’ve achieved maximum run times,” she says. “Many companies are operating for 20 hours.”

Of course, when choosing a heat exchanger, it’s important to remember that run times vary across products. And different processors have different requirements. As Fryer puts it, “what’s a long run for one product may be short for another.” The best course is for a company to assess its individual needs, and then find an exchanger that best fulfills them.

Promoting cleanability

Food safety and sanitation best practices are a major focus for the food industry — now even more so, as FSMA deadlines approach. Clearly, part of a good hygiene program is making sure that equipment not only is easy to clean, but also stays as clean as possible for as long as possible.

As such, Fryer says her customers are always concerned about the cleanability and overall hygiene of their heat exchangers. Here, similar to run times, design is a major factor, specifically as it relates to flow rate during CIP.

“For plates, cleanability is highly dependent on flow rate. You want to have a high enough flow rate to provide good velocity and turbulence to remove whatever’s built up on the plates.”

She adds that a properly designed plate heat exchanger should be able to clean all sections at the same flow rate. “We build that into the design of what we provide for our customers,” she says. “We keep the cleaning aspect in mind.”

Quality of the materials of construction can also be a factor in promoting cleanability. Kelvion utilizes a high annealed surface finish for the material that is typically used in the food industry. This results in lower roughness, which provides the benefits of less fouling and longer production time.

To ensure that heat exchangers are properly cleaned and sanitized, processors should also use certified parts, address surface anomalies, and perform regular maintenance and inspections, among other things. This article from Dairy Foods has more detailed advice on the topic from Fryer and other experts.

Keeping up with food trends

Innovation in heat exchangers is often driven by food trends. “I’ve watched a lot of food trends come through the heat exchanger market,” Fryer says, citing everything from fat-free products to energy drinks. She notes that current hot products include smoothies and different types of beer.

With each new trend, engineers have to figure out how best to handle the product. Fryer offers the example of fat-free products, which act differently from their full-fat counterparts.

“What’s odd with fat-free products is that when they hit a certain temperature, they get very viscous. So they’re more viscous on the cooling side than on the heating side.” She explains that during the fat-free craze, engineers had to adjust the design of heat exchangers to compensate for those properties.

Today’s smoothie trend presents a different challenge, similar to other products that may contain pulp or particulate. Fryer says that while some plate heat exchangers can’t be used for such products, Kelvion’s Free Flow plates are designed to process them effectively.

“We have a Free Flow plate with an even 5-millimeter gap where the product flows,” she explains. “The exchangers can handle more fine particulate, so products like pulpy juices, smoothies, and sauces can be processed on a plate heat exchanger instead of processors having to go with another technology that isn’t as efficient.”

While Fryer isn’t sure what trends will come next, she says engineers will be ready to make the necessary adjustments.

New heat exchanger technologies

The cutting edge technology in plate heat exchangers is apparent in equipment like Kelvion’s NT line, which Fryer calls “one of the most technologically advanced on the market.” In developing this line, the engineers used computer modeling to address common plate issues.

For instance, “one of the inherent problems of plate heat exchangers is that there is  a higher flow and velocity on one side of the plate than on the other.” Computer modeling allowed Kelvion to design a plate that provides an even flow, “so you don’t have to worry about those areas of low velocity, which minimizes fouling rates, plate count, and cost.” Fryer explains that this is achieved by making the entire plate — rather than just the top portion — an area of flow distribution.

Kelvion’s products are also a good example of the latest in self-aligning plates. “We have a corner interlocking system, and the whole gasket groove is a plate alignment,” Fryer says. “That allows you to button up the heat exchanger and have it in alignment much easier.”

An easy closure feature with the Eco-Axs frame adds to this efficiency. “If there’s a breakdown, everyone is concerned about getting in, fixing the problem, and getting out as fast as possible.” Fryer points out that quickly opening and closing the machine is helpful for inspections, as well, which may become more frequent with FSMA implementation.

Kelvion offers several control options for its Eco-Axs frame, including a fully automated and “smart” system, as well as one that requires a bit more human oversight. In both cases, closure to the desired dimension is achieved with the pressing of a button. “You don’t need to have people with wrenches tightening down the nuts and bolts,” Fryer says.

As heat exchanger technology continues to advance, Fryer hopes to see more processors adopting the new and more efficient machines that are available today. She says that familiarity with older equipment can make businesses reluctant to change. But once they do, they’ll see immediate gains in hygiene productivity and profitability.