Running Hot and Cold
by Lynn Petrak
The latest heat exchanger technologies reflect
improvements on a classic design.
Hot things should stay hot.
Cold things should stay cold. Perishables should stay safe.
Those are not complex concepts, but in the production
of dairy products, controlling the heating and cooling process comes down
to the reliability of equipment.
Heat exchangers, including sanitary heat exchangers
used during product processing, are critical in dairy processing facilities
because of their function in heating, cooling and pasteurizing dairy
beverages and foods. As a testament to their function and performance, heat
exchangers have been around for decades, with some models in today’s
plants dating back decades.
Despite the longevity and proven track record of heat
exchangers, equipment manufacturers continue to tweak heat exchanger
designs to increase efficiency, help save resources and accommodate for
different product types and resulting flow rates. Enhancements have been
made for different types of heat exchangers — including plate heat
exchangers, tubular heat and scraped-surface exchangers — as well as
for gasketed and welded units. Suppliers are updating both sanitary heat
exchangers and heat exchangers for utility purposes.
John Bohn, director of engineering, co-owner and
founder of AGC Engineering, Bristow, Va., has seen firsthand the evolution
in dairy manufacturing and its impact on basic equipment like heat
exchangers. “The technology many people have in their plants was
developed in the 1950s. When I mean upgrade, I really mean we can help
bring them into the 21st century,” he says.
Another supplier who says the time is right for a fresh
take on this equipment mainstay is Carl Lemke, business development
manager, plate heat exchangers, for the Pleasant Prairie, Wis., sanitary
segment group of Alfa Laval Inc. “A lot of our customers are taking a
look at new technology to replace things that have been around for 40
years,” he says.
Whether they are replacing aging systems or building
new plants with state-of-the-art systems, processors want modern heat
exchangers to deliver a multitude of benefits. “All of our
clients are concerned with expanding capacity while minimizing capital
investment and conserving floor space. The driving forces are the combined
demands from expanding business, competitive pricing, and the consolidation
of plants,” says Tony Mathis, technical product manager for Waukesha
Cherry-Burrell, a unit of Delavan, Wis.-based SPX Process Equipment.
According to Don Bohner, manager, heat exchangers for
Vernon Hills, Ill.-based Tetra Pak Inc., plants have the same requirements
for heat exchangers as they do for other types of equipment — namely,
performance. “Energy, efficiency and flexibility are all important,
but when it boils down to what is really important to the processors is,
will the heat exchanger process their specific product, at the desired flow
rate, at the required temperatures, and do this with little or no
breakdowns,” he says, adding that downtime is a luxury that
today’s processors cannot afford.
To Bohner’s point, reliability is a key demand of
today’s dairy companies, including both large dairy conglomerates
that continue to consolidate operations and smaller, regional companies
trying to stay competitive and rein in costs. As part of their own R&D
process, suppliers of heat exchangers have worked to improve the
performance of their respective heat exchanger models.
Tetra Pak, which supplies a range of plate and tubular
heat exchangers, has introduced new units and features in response to
customer demands for consistency and low maintenance. Recently, the company
refined its technology to bring together its Tetra Plex M and Tetra Plex
MBasic range of plate heat exchangers into one range. “We combined
the low cost of the Tetra Plex MBasic frame with the more robust Tetra Plex
M frame into one frame that will not only meet the new 3A Sanitary
Standards, but will be a great value with much higher operating
pressures,” Bohner explains.
In addition, Tetra Pak is now offering a larger
scraped-surface heat exchanger that enables users to reduce the number of
required cylinders and hence lower maintenance costs. Processors also can
choose from the supplier’s Tetra Plex range of plate heat exchangers
with high pressure frames that have a maximum operating pressure of up to
290 psi. “The higher-pressure frame addresses the need for more
reliability thus decreasing downtime,” Bohner says, adding that
low-carb and lowfat products also tend to create higher pressures.
Alfa Laval, for its part, has pursued what it deems to
be the next generation of heat exchangers. Its most recent sanitary heat
exchanger is a unit called the AlfaNova. “That is a solid heat
exchanger with completely stainless steel construction created using a
special fusion process. It is able to handle very high temperatures and is
compact and efficient,” explains Lemke, echoing the fact that
customers are seeking consistent, high-quality performance. “They
want something that is very reliable.”
The R&D team at Waukesha Cherry-Burrell is also
driven by manufacturers’ demands for reliability. A year and a half
ago, the company upgraded its 4x120 scraped-surface heat exchanger for
medium to light-duty applications. “We eliminated the drive coupling,
improved the jacket design and changed to a high-performance plastic for
the molded scraping blades,” Mathis says.
Waukesha Cherry-Burrell also has enhanced its
Votator-II line of scraped-surface heat exchangers, which were developed in
1998 for medium to heavy-duty heating or cooling applications. “We
have continuously refined and simplified maintenance items like blades and
mechanical seals and improved design of our refrigeration control
circuits,” says Mathis, noting that the Votator II series can be used
for the injection of viscous variegates into ice cream, process cheese,
yogurt, whey concentrates and sour cream.
Meanwhile, as dairies continue to diversify their
businesses and introduce new product lines, reliability is just as
important for emerging processes. Viscosity, for instance, has been a key
variable in the manufacture of many of today’s dairy-based foods and
beverages. “We have seen an increase in more viscous products or
those with particulates that require processing,” says Damon Wright,
who works in heat exchanger projects for Lake Mills, Wis.-based Invensys
APV, a division of Invensys plc that supplies plate heat exchangers and
tubular heat exchangers for heating as well as for flash cooling.
To help manufacturers solve challenges with more
viscous products, APV offers its R5 Quad-Drive plate exchanger and is
working on a soon-to-be-introduced V plate that can be used for low-flow
applications. For dairies that are implementing more ultra-high-temperature
(UHT) processes, APV’s tubular units can be used, says Wright.
“In higher fouling applications like UHT, then a tubular can provide
longer run times and provide flexibility with products with
particulates,” he says.
AGC, too, has worked with dairies encountering
challenges with products that are more viscous and that contain more
particulates “Things like lowfat and low-carb ice cream mixes have
high solids and are unpredictable,” explains Bohn. “With our
Pro5, you can process varying range of viscous mixes from soft serves that
are real light and low solids to something that is 45 percent solids and 15
to 18 percent fat and heavily stabilized.”
Even new products currently in the R&D phase are
being processed using heat exchanger technology created to be more flexible
and reliable than ever. Microthermics Inc., Raleigh, N.C., offers
compact heat exchangers as part of its comprehensive processing systems
used to replicate plant conditions in pilot facilities and R&D
“With our plates, you can change the amount of
heat exchange area in your final heat sections and cooling. It literally
gives you an endless set of permutations you can reach,” says company
vice president David Miles.
Sizing it Up
In addition to reliability and versatility, another
trend impacting heat exchanger technology relates to size. “If
anything, capacities are getting larger, which is causing suppliers to look
at larger capacity equipment,” Bohner says.
Lemke concurs. “Everything is getting bigger.
Companies are consolidating and small dairies are becoming two or three big
dairies. They are looking for bigger units to meet demand,” he says.
In response to bigger-is-better movement, providers of
heat exchangers are offering models designed to handle a greater volume and
range of products. In addition to Alfa Laval’s AlfaNova and Tetra
Pak’s latest high-capacity designs, AGC is promoting its Pro5 and
Pro5 Plus series of heat exchangers to dairies with greater capacities.
“If you have a typical unit running 5,000 gallons an hour, you can go
to 6,500 to 7,000 gallons an hour with no piping changes by upgrading the
heat exchanger with a Plus plate,” Bohn says, adding that higher flow
rates can translate into real bottom-line improvements. “When you
talk about production, time is money.”
Waukesha Cherry-Burrell also has altered heat exchanger
technology for capacity purposes. Among other upgrades, the company
expanded its Votator-II platform into heavy-duty applications, according to
Even as heat exchangers are designed to go with a
bigger flow, so to speak, dairy processors don’t want units, whether
large plates or extensive tubular systems, taking up too much space.
According to Lemke, the new Alfa Nova is “a fraction” of the
footprint of traditional heat exchanger systems. Other contemporary heat
exchangers, including tubular, plate and scraped surface designs, have been
created to help processors save on floor space, which is at a premium in
Energy and Utility Issues
Operational considerations can play into heat exchanger
technology as well. The desire to save energy — to both
conserve resources and cut costs — is one factor in heat exchanger
purchases and upgrades and has been a related topic for years.
“Energy concerns have been an issue since the early 1980s and even
earlier,” Bohner says, adding that Tetra Pak provides milk
pasteurizers with regeneration (regen) efficiencies of up to 96 percent.
Energy issues often vary by region. “In states
where water is limited or power consumption issues, like in the Southwest
or California, we have seen more requests to maximize regen on a plate heat
exchanger,” says Wright, who notes that APV’s plates provides
90 percent regen for most dairy applications. Mathis also points out that
incentives also differ based on geography. “There are states or
regions where our customers receive discounts from their energy suppliers
for the use of high-efficiency electric motors.”
In response to dairies’ desire to conserve energy
and reduce utility costs, many of today’s heat exchangers include
energy-efficient features. According to Mathis, Waukesha Cherry-Burrell
helps customers optimize energy consumption by dividing cooling duty.
For example, some Votator units pre-cool the product using a low-cost
tower water supply before the final temperature is reached, using Votator
units with a less energy-efficient chilled water or direct expansion
refrigerant like ammonia. “Often a single extra Votator unit can be
added to reduce the required refrigeration compressor duty by 50 percent,
compared to doing the entire cooling range with refrigerant,” Mathis
Finally, in addition to sanitary heat exchangers that
have been created or upgraded to run as efficiently as possible, utility
heat exchangers are also focal points of improvements.
Alfa Laval, for instance, has come out with a TS6 model
developed to replace traditional tube and shell systems, according to
Lemke. “It takes up a small footprint and is more flexible. The TS6
models are also prepackaged and shipped to the consumer, which reduces
fright costs,” he says.
Tetra Pak also has launched a compact tubular heat
exchanger for utility functions. The Tetra Spiraflo CIP and Water Heater is
used to heat clean-in-place (CIP) solutions and to make hot water that can
be mounted off the floor in a vertical or horizontal position.
“Maintenance is extremely low,” Bohner says, “and we are
now stocked for immediate delivery.”
Lynn Petrak is a freelance journalist based in the
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