Refrigeration – Liquid contacting discrete commodity – With article conveyer or transporter
Patent
1990-02-06
1990-11-27
Capossela, Ronald C.
Refrigeration
Liquid contacting discrete commodity
With article conveyer or transporter
62 63, 62380, F25D 2504
Patent
active
049726811
DESCRIPTION:
BRIEF SUMMARY
The present invention generally relates to a freezing device for freezing products, such as foodstuffs, which freezing device is designed as a substantially closed container having a top side provided with a feed opening and a discharge opening, and particularly to a new device for maintaining constant the level of a cooling medium in such a container.
It is known to design a freezing device as a substantially closed container in order to enclose a cooling medium in the container.
EP No. -A3-0,084,683, for example, discloses a freezing device which is designed as a substantially closed container having a feed opening and a discharge opening, in which container a cooling medium is enclosed if conveyors provided in the container maintain a certain feed rate, such that the product flow counteracts the flow of cooling medium, whereby equilibrium is achieved and the cooling medium is enclosed in the container.
U.S. Pat. No. 3,485,055 and U.S. Pat. No. 3,774,524 also disclose devices which are designed as substantially closed containers, the latter reference in particular illustrating in one embodiment product infeed and outfeed through a water bath, thus preventing a gaseous cooling medium from escaping from the container.
Enclosing a cooling medium in a container which is provided with openings and also charged with products to be frozen, in which case the cooling medium is evaporated and thus is more liable to escape from the container, and maintaining the cooling medium on a constant level thus are problems which are difficult to solve in an appropriate way.
U.S. Pat. No. 4,448,029, for example, discloses a device for removing excess cooling medium formed when freezing various products, such as foodstuffs, in which device a pipe system is connected to a fan continuously sucking a mixture of air and gaseous cooling medium out of the freezer.
The said container and suction devices however suffer from a number of serious drawbacks. In many devices, there is a very substantial risk of leakage of cooling medium through the feed and/or the discharge opening. The cooling medium, most often being liquid nitrogen, evaporates and produces nitrogen gas which, in connection with functional trouble or upon a rapid increase of the amount of nitrogen gas, may escape from the freezing device, the leaking nitrogen gas cooling the ambient air and, at worst, may reduce the oxygen content of the air in the working premises to a critical limit.
A further drawback inherent in the prior art technique when sucking off the excess nitrogen gas formed during the freezing of different products is that the removal of the gas by suction creates a depression within the freezer. This depression is equalized by relatively warm ambient air being sucked through openings into the freezer where it gives rise to increased production of nitrogen gas. This phenomenon reduces the efficiency of the freezer since part of the nitrogen takes up the heat from the air and not from the products to be frozen.
The drawback of letting the products pass a water bath separating the interior of the freezer from the surroundings is, for instance, that the products must be resistant to moisture, which is quite inconvenient, inter alia in respect of food technology requirements, hygiene and appearance.
One object of the present invention therefore is to provide a device for maintaining constant the level of a cooling medium in a freezing device.
Another object of the present invention is to enhance the degree of utilization of the freezing device and to protect the environment proximate to the freezing device from undesired emissions of cooling medium from the freezing device.
Also, the new device for maintaining the cooling medium on a constant level should be of simple construction, it should not restrict the field of use of the freezing device, and it should be inexpensive to manufacture.
These and other objects of the invention are achieved by means of a freezing device using a cooling medium which takes up heat during the freezing process and which then at le
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Capossela Ronald C.
Frigoscandia Contracting AB
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