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On the cold front: Heat exchanger cools bulk marinades fast without damaging the product

Ready Foods has long used water baths to chill its kettle-cooked products, which are typically packaged in small pouches. But when a customer requested much larger quantities of the company’s adobo marinade, Ready Foods realized that water baths just wouldn’t cut it. That’s when the Denver, Colorado-based processor turned to HRS Heat Exchangers for a turnkey heat exchanger system that could cool its adobo marinade in bulk capacities much faster and increase throughput.

The family-owned food company manufactures about 150 products, ranging from sauces and soups to beef fillings and Spanish rice, for food manufacturers and restaurants in the Western and Rocky Mountain regions of the United States. It kettle-cooks the products in small batches and hot-fills them into 5-lb and 10-lb pouches before sending them off to be cooled in a water bath system. That cooling system is a cost-efficient solution for Ready Foods’ usual 5-lb and 10-lb pouches. But the company knew it would have to come up with an alternative cooling solution when a leading Mexican quick-service restaurant chain asked the company to prepare its adobo marinade in 2,000-lb totes. Ready Foods recognized that its water bath system would not be able to chill that larger capacity quickly enough to fulfill the customer’s order on a regular basis. 

Cooling-off period

The processor decided to work with HRS Heat Exchangers to customize a two-stage heat exchanger system that could chill the adobo marinade from 200°F to 38°F safely and efficiently without damaging the gritty, viscous product. The system consists of two Unicus reciprocating scraped surface heat exchangers and 10 AS 3 Series triple-tube heat exchangers, both driven by BP-6 hydraulic piston pumps. 

After the adobo marinade is cooked and steamed, transfer pumps move the hot product from the cook kettles to the balance tank. Once the tank is full, the BP-6 hydraulic piston pumps push the marinade through the system in a slow, up-and-down motion to ensure minimal shearing of the product and prevent friction. The marinade, which ranges in temperature from 185°F to 200°F at this stage, first flows through the AS 3 Series triple-tube heat exchangers, which serve as a pre-cooling mechanism. The pumps transport the product through the annular space, while chilled water is pumped through the inner and outer tubes to ensure even cooling. Once temperature transmitters indicate that the marinade temperature has been reduced to at least 70°F, the pumps move the product to the Unicus reciprocating scraped surface heat exchangers for final cooling. 

The Unicus reciprocating scraped surface heat exchanger features a traditional shell and tube design with scraping elements attached to a shaft inside each tube. Nontoxic glycol flows through the shell to cool the marinade, which is pumped through the tube. Instead of rotating the shaft as is typical with other types of scraped surface heat exchangers, the Unicus moves the shaft with the scrapers back and forth in the tube. That reciprocating motion minimizes shearing on the product, scrapes the inner surface of the tube to prevent fouling and increases turbulence of the viscous product so that it cools down faster. 

When the marinade is chilled to about 38°F in the Unicus heat exchangers, the piston pumps take the product to a three-way valve. If the temperature transmitters on the valve determine that the temperature target for the product was met, the valve will send the marinade to a filler tank. If the marinade doesn’t meet the temperature target or the filler tank is full, the valve will divert the marinade back to the balance tank.

Chilling effects

Since Ready Foods began using the HRS heat exchanger system in September of 2018, the company has been able to cut the chilling time of its marinade by one-third. “So we’re cooling the same amount of product in a batch, which is roughly 2,400 pounds, in less time,” says Greg Hefter, director of engineering at Ready Foods. “To cool 2,400 pounds in 10-pound pouches took three hours. To cool 2,400 pounds in the HRS system for filling a tote, we can do that in one hour.”

Ready Foods has also been able to increase throughput. The company is producing about 240,000 lb of marinade a week by running the heat exchanger system 24 hours a day for five days a week. “When we started using the HRS equipment, our requirements were 60 to 70 batches a week. Now we’re up to 110 batches,” Hefter says. “So we’ve gone from a two-shift operation to a three-shift operation five days a week.”

Ready Foods also appreciates that HRS created a cooling system that is appropriate for a medium-sized company like itself. For example, HRS was able to provide a complete turnkey system and integrate it into Ready Foods processing line. In addition, Ready Foods says the HRS system is simple for its operators to use, including a user-friendly human machine interface (HMI) with specifications and alarms programmed into it. And because many of the employees speak Spanish, HRS incorporated a feature on the main page of the HMI that allows them to toggle between English and Spanish. The three-skid system also takes up a smaller footprint than other systems the company looked into. 

“We are a medium-sized company, but it became clear that most of the equipment suppliers we talked to were accustomed to dealing with much larger firms than ours. Their proposals were totally unsuitable for our size of operation,” says Marco Antonio Abarca, president and owner of Ready Foods. “What we liked about the HRS system is that it’s well-designed, rugged and not overly complex. It’s the right technology for us to handle at this time.”