IceDry® Increases Efficiency of Unilever Freezer
20 July 2004 10:49
In freezer production, icing often causes interruptions, food releases moisture and becomes water vapour, which coupled with the moisture in the air and cleaning can all make the equipment ice up rapidly. The consequence is frequent productions stoppages to defrost and clean.
Productivity improvement and safeguarding quality are a constant concern, especially in freezer production, where avoiding stoppages due to defrosts and unnecessary cleaning due to ice build up means significant productivity gains.
At the Technology-Centre of Langnese-Iglo part of the Unilever Group, the team adapt existing production methods to the new conditions, to stay competitive in the European market
The production of bread and pastry snacks (frozen Bistro-baguettes brand) is an around the clock, three-shift-operation. The cause of the disruption was the icing up of the freezer. The baguettes are packed after being frozen, to avoid sticking together of the topping with the packaging. However the fresh ingredients release a lot of moisture. Also the difference in pressure between the air in the freezer and the surrounding air causes moist outside air to be drawn into the freezer. All this causes condensation and icing up of the evaporators, which in turn reduces the cooling effect and the conveyor belt has to run slower so that the products can be frozen sufficiently.
After four shifts, production was stopped to defrost and clean the freezer. “Each defrost meant up to six hours production interruption and the employment of two staff, who have to defrost the freezer with water,” explained the Head of the Technology Centre. “The freezer is the central part of the production line with a life span of 10–20 years”, said Langanese –Iglo. The solution came from Munters who extract moisture from the air before it condenses on the evaporator and slowly ices up, at the product entry into the freezer. The air is sucked into the air-lock through Munters IceDry® system, which is installed on top of the freezer, then dehumidified air goes through the air-lock and back into the production area.
To avoid moist air reaching the freezer through the product entry and exit, the IceDry® air is supplied using a positive pressure and therefore an air exchange with the warm, moist surrounding air is avoided.
By using Munters IceDry® the freezing of the evaporator was reduced, previously the freezer had to be defrosted and cleaned after 3-4 shifts, now this has been extended to 6-7 shifts. That’s not only almost doubling the running time, but also a constant running speed.
At Langnese-Iglo they also produce high quality frozen ready-meals. Here frozen ingredients are mixed in the freezer installation and are dealt with by electronic scales, which always empty their small bowls, when the right amount of frozen vegetables are weighed. Since this is carried out under freezing temperatures, the scales often malfunction because of the ice build up.
Every time during cleaning, moisture entered the air in the room, which after a short time formed frost. The fine mechanism of the bowls jammed and production had to stop”, explained the Head of the Technology Centre. “In addition the floor was icing up badly and the accident risk for staff increased. Besides regular stoppages, the safety risk was not acceptable for us”.
With Munters IceDry® when cooling to minus temperatures no ice forms because the air has low moisture. In production disruption through new frost forming has been significantly reduced with the help of dry air being blown in and the safety risk for employee slips has dropped considerably. The Munters IceDry® system takes care that the highly precise scales providing a trouble free operation.
For more information on this company:
Munters - Frost Prevention in Freezing and Cold Storage with Humidity Control
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