Case Study

Scraped Surface Heat Exchanger Solves Uneven Cooling Problem for Poultry Processor

Foster Farms is one of the largest and best-known poultry companies in the U.S. The company employs 7000 people in all, a thousand of whom work at the facility in Turlock, California - which processes turkey products. After the fleshiest parts - the thighs and breasts - have been removed from the carcass, there is a lot of meat left that must be utilized economically and efficiently. As much as 70% of the total carcass weight is pure meat. The carcass is deboned and the meat is ground. Among other things, the product is used in hot dogs, cold cuts and as raw material for the food industry.

During the deboning process temperature is increased in the product. Strict demands apply to hygiene. To prevent the growth of bacteria, the product is cooled down from 13 to 2.5° C.

"We used to use the traditional method of cooling the mechanically deboned meat with CO2," says Jim Theis, director of operations. "That method had a lot of disadvantages. In the long run, the cost of CO2 was way too high, and the cooling was uneven. In practice that meant that we had to cool some of the product so drastically that it froze, in order to be sure of getting a low enough temperature through the entire batch. That meant inconsistent quality, and sometimes product shutdowns."

The solution to Foster Farms' problem was Contherm, a cylindrical scraped-surface heat exchanger from Alfa Laval, specially constructed for heating or cooling viscous, sticky and chunky products.

In the Contherm, products are chilled or heated without air contact. Its construction is well thought through - Conterm requires little floor space, cuts down on labor and needs minimum maintenance. The apparatus is also easy to clean, even though it handles demanding products. Contherm comes in various sizes and offers a number of features that can be adapted for different applications. Ammonia is the cooling medium used in the Contherm units at Foster Farms. The combined capacity of the two units used in this application is 3,600 kg of product per hour.

How Contherm Works
Product is pumped into the lower end of the heat exchange cylinder. As product flows through the cylinder, it is continuously agitated and removed from the cylinder's precisely finished walls by the scraping blades. This scraping action results in thin film product heating or cooling, a surface free from fouling deposits, and a corresponding high heat transfer rate.

The rotor can be driven by either a top mounted electric (belt & sheave or direct coupled) or hydraulic motor drive. Product flow and rotor speed can be varied to suit the properties of the product flowing through the cylinder.

The rotors and tangential inlet/outlet ports are specially designed to improve food processing. Rotor diameter and pin/blade configurations can vary to suit different applications. Smaller diameter rotors allow larger particles to pass through the cylinder, while larger diameter rotors result in shorter residence times and improved thermal performance.

Heating or cooling media flow in the annular space between the heat exchange cylinder and the insulated jacket.

Processing Costs Reduced
Jim Theis is pleased: "Our two Contherm units have radically reduced processing costs. The investment paid for itself in less than two years. And at the same time, we have gained much better control over the cooling process. Contherm provides absolutely uniform cooling, and now we can cool all the deboned meat to exactly the right temperature, which results in an end product of both high and consistent quality. Changing over from the old system posed some problems, but we got the support we needed from Alfa Laval, and we are absolutely delighted with the final result."

For more information contact Alfa Laval Thermal Food Center, 111 Parker St., Newburyport, MA 01950. Tel: 978-465-5777; Fax: 978-465-6006.