Field Report: Rebuilt cooling system puts wasted time and money on ice

Frozen food plant upgrade yields 13-15 percent savings.

The upgraded vacuum cooling system at the Heinz Dundalk plant is larger than the original, offering additional capacity. Before the new condenser was received, plant personnel modified the platform to accommodate its longer length. Source: Croll Reynolds.

WITH 20 TONS OF PRODUCT RUNNING THROUGH ITS plant and another 20 tons in preparation at any given time, keeping cool at the Heinz Frozen Foods plant in Dundalk, Ireland, is imperative. The plant produces a variety of beef, lamb and vegetable sauces that, with added ingredients, become ready-made frozen dinners. Five five-ton cooking kettles are used, served by four five-ton stock tanks, to hold the sauce on line and ready for filling into the kettles.

"We use two three-stage vacuum cooling systems for five kettles," says Micheal McNally, utility supervisor for the plant. "Cooking isn't everything in the food processing industry. With the amount of product we have in preparation, expedited cooling is equally vital."

Management at the Heinz Dundalk facility realized just how vital cooling could be when one of its vacuum cooling systems started to deteriorate rapidly, wasting large amounts of cooling water and ejector motive steam. With production running six days a week, 24 hours each day, the system needed to be brought back on line quickly. "Since Croll Reynolds originally manufactured the system, they were the logical choice to ask to rebuild and modernize it," says McNally.

The team designed the replacement elements to fit into the existing system. Those elements included a new main intercondenser and a liquid ring vacuum pump, which would replace the failing second-stage ejector, secondary intercondenser, third-stage ejector and aftercondenser. The existing two-stage low vacuum ejector system was replaced with two, 30 HP single-stage Robuschi liquid ring vacuum pumps, only one of which operates at any given time. "The two vacuum pumps run on a controlled system, so if one doesn't start up or trips out, the other will automatically come on," says McNally. "We also stagger pump operation so that both pumps receive equal wear."

The new system also features a condenser shell equipped with hinged channel covers. To inspect or clean the tubes, the channel cover bolts are loosened and the channel cover is swung away on a davit hinge. To further simplify maintenance, 25 mm tubes, as opposed to 19 mm, were installed because they can be easier to clean and, according to the system's designers, can be expected to stay clean longer.

Cooling for a typical 4 1⁄2-ton batch, which in the past required approximately 70 to 90 minutes, can now be completed in 50 minutes. The Heinz Dundalk plant is also saving water thanks to the new arrangement. In the original system, the failing third-stage ejector and the 75 kW water pump supplying cooling water to the existing aftercondenser ran continuously. The renewed system circulates water on demand; the water pump runs only when a batch is actually being cooled. "This is virtually a complete new system," says McNally. "We estimate a 13-15 percent savings for the upgraded system and we have the greater benefit of faster process time."

For more information:
Henry Hage, Croll Reynolds, 908-232-4200,
hhage@croll.com