Refrigeration – Processes – Treating an article
Patent
1997-08-19
1999-03-16
Capossela, Ronald
Refrigeration
Processes
Treating an article
62 74, 62 78, 62374, F25D 1306
Patent
active
058815619
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for freezing fluid substances with the aid of a cryogenic fluid, in particular with the aid of liquid nitrogen.
It is known to freeze the fluid with a view to the preservation of fluids. In cases of fluids of this kind this may involve, for example, suspensions of bacteria, solutions of albumen or inoculation serums. The freezing procedure should take place as quickly and as uniformly as possible, to prevent damage due to the cold, which could appear as a result of the growth of ice crystals. The freezing procedure is usually performed by making use of a fluid gas with a low boiling point, in particular of liquid nitrogen.
A device for freezing fluid substances with the aid of a cryogenic fluid is described by J. Buchmuller and G. Weyermann in the paper called "Cryopel: Ein neues Verfahren zum Pelletieren und Frosten biologischer Substrate" device includes an immersion freezer compartment which is constructed basically in a U shape, metering equipment and withdrawing equipment. A cryogenic fluid is in the immersion freezer compartment. By virtue of the metering equipment which is constructed in the form of equipment producing a drop, a fluid is introduced into the immersion freezer compartment. By virtue of the immersion of the drop in the cryogenic fluid the fluid freezes very abruptly at its surface. A conveyor belt which has driving members is placed in the immersion freezer compartment with a view to the removal by conveying of the pellets thus produced. The conveyor belt is endless.
A device for freezing fluid substances with the aid of a cryogenic fluid, in particular with the aid of liquid nitrogen, is known from U.S. Pat. No. 4,982,577. The device includes a receptacle in the form of a small cask, in which a conveying channel designed in the shape of a screw is placed. The conveying channel forms a slipway on which the cryogenic fluid slides with the fluid to be frozen in the form of pellets in the direction of a withdrawing equipment.
SUMMARY AND OBJECTS OF THE INVENTION
The fundamental objective of the present invention is to provide a device and a process by virtue of which it is possible to reach a high freezing efficiency, the size of the pellets being as uniform as possible.
This objective is obtained by virtue of a device according to and a process according to described below. Subsequent advantageous developments form the subject of the secondary claims.
The device according to the invention is characterized in that the conveying channel has, from the view point of the conveying direction, at least one section which is inclined to the horizontal, to which is adjoined a section arranged essentially horizontally. The section arranged horizontally has conveying equipment.
The fluid to be frozen in the form of drops is removed by conveying with the aid of the cryogenic fluid which flows in the section which is inclined in relation to the horizontal of the conveying channel. By virtue of the removal of the fluid to be frozen by immediate conveying it is ensured that the drops or the pellets do not collide with one another. It is by virtue of the fact that a collision of the drops with one another does not take place that virtually all the drops are of a uniform size.
The pellets undergo a commencement of freezing in an outer region in the section which is inclined in relation to the horizontal of the conveying channel. In the section arranged essentially horizontally of the conveying channel, which adjoins the section which is inclined in relation to the horizontal, each pellet is completely frozen individually. This is produced by the fact that the section arranged essentially horizontally has a conveying equipment, with the aid of which the speed of conveying of the pellets in the cryogenic fluid can be adjusted.
The conveying equipment is formed by virtue of the section which is inclined in relation to the horizontal, which is connected to a vibrating drive. Preference is given to a vibrating drive which involves, for example, an ultrasonic source which in
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patent: 3228838 (1966-01-01), Rinfret et al.
patent: 3413818 (1968-12-01), Pelmulder
patent: 4655047 (1987-04-01), Temple et al.
patent: 4748817 (1988-06-01), Oura et al.
patent: 4982577 (1991-01-01), Milankov et al.
patent: 5299426 (1994-04-01), Lermeuzeaus
Capossela Ronald
L'Air Liquide Societe Anonyme pour L'Etude et L'Exploitation des
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