Refrigeration – Withdrawable liquid – e.g. – dispenser
Reexamination Certificate
1999-04-01
2001-04-10
McDermott, Corrine (Department: 3744)
Refrigeration
Withdrawable liquid, e.g., dispenser
C062S392000
Reexamination Certificate
active
06212899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus and cooling system particularly, but not exclusively, for use in the food or liquor industry.
2. Description of the Related Art
A known form of cooling system which is utilized in the dairy industry includes a ply heat exchanger for cooling milk from dairy cows to a temperature of about 4° C., to inhibit bacterial growth whilst the milk is in a storage vat awaiting transport to a milk tanker. The bottom of the vat may be formed of a second “dimple plate” heat exchanger which is cooled by refrigerant or chilled water to maintain the milk at a low temperature. A mechanical agitator may also be provided in the vat to circulate the milk so as to maximize efficiency of the dimple plate heat exchanger, prevent separation of the milk particles and also to prevent stratification of the milk.
The plate heat exchanger is form of a plurality of thin plates which are connected in a sandwich type construction. Each plate has chilled water running through it for heat exchange with milk running over the plate. The manifold structure of the plate heat exchanger makes it prone to bacterial contamination. After each milking, the heat exchanger is taken out of line and flushed clean. Less frequently, the entire heat exchanger needs to be disassembled either for removing clogging deposits or for regulatory inspection. Assembly and disassembly of the plate heat exchanger is extremely labor and time consuming.
Aside from the above disadvantages, the conventional milking system has limited capacity for fluctuation in milk volume or flow rate due to limited supply of chilled water. The chilled water is obtained from a water tank, which may be cooled by refrigeration, or from an “ice bank” tank. The dimple plate heat exchanger may also be cooled by chilled water from either the water tank or ice bank tank. Known forms of ice bank tanks and water tanks for use in the above system have a large volume and are usually cooled to, for example, 0° C. overnight to capitalize on offpeak power rates. The volume of the tank is generally sufficient to cater for a day's milking. However, when the amount of milk to be cooled is greater than normal, the capacity of the tank may not be sufficient, and the milk consequently may not be cooled to a low enough temperature. Further, the plate heat exchanger is generally constructed to cool a certain volume of milk over a predetermined time, i.e., at a given cooling rate. If the rate at which milk is collected from the cows is greater than normal, the milk will again not be sufficiently cooled. The capacity of the plate heat exchanger may be increased by connecting more plates to the beat exchanger but this is a rather complicated and time consuming process.
If the milk is not adequately cooled by the plate heat exchanger, supplementary cooling may be effected by the dimple plate exchanger on the bottom of the vat, but such cooling is not as efficient as the plate heat exchanger.
An arrangement is disclosed in GB 1465516 (Alfa-Laval Industrie-Technik GmbH, filed Jul. 14, 1973) where a two stage cooling process is utilized. Milk is firstly pre-cooled by an in-line heat exchanger and delivered to a vat, in a conventional manner. The pre-cooled milk is then recycled back through the heat exchanger after completion, or during interruption, of a milking operation to achieve a storage temperature of about 4° C. The arrangement includes non-return valves for controlling fluid flow during each cooling stage.
OBJECT OF THE INVENTION
The object of the arrangement is to cool and maintain milk at a required storage temperature without the need for additional cooling devices, such as the above described dimple plate heat exchanger, in the vat itself. To applicants knowledge, the arrangement has never been commercially adopted. A possible reason could be regulatory, since the one way valves, essential for correct fluid flow of milk through the heat exchanger, provide ideal sites for bacterial growth. In any event, the arrangement would still have all the attendant disadvantages when used in conjunction with a conventional plate heat exchanger in the above described system.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a cooling system for cooling liquid transferred into a vat along a fist flow path, the system including an apparatus for heat exchange with liquid passing therethrough, wherein a second flow path is provided for circulating the liquid in the vat through the apparatus and the second flow path is isolated from the first flow path. Preferably, the apparatus includes a casing through which the liquid flows and a refrigeration element in the form of a cylindrical coil mounted within the casing, the coil having a refrigerant input and refrigerant output provided at one end thereof and the casing including a close portion, remote from the one end of the coil, wherein the closure portion is releasable to allow the casing to be removed by sliding over the coil in a direction away from the one end.
Preferably the system includes a coupling device which is adapted to selectively connect and disconnect the cooling apparatus between the second flow path and a third flow path, the third flow path being for transfer of a second liquid between a storage tank, connected to the coupling device via a pair of transfer pipes arranged to allow flow of the second liquid from the tank to the cooling apparatus and to return the cooled second liquid from the apparatus to the tank, the storage tank being in fluid communication with a plate heat exchanger and first and second conduits being provided to circulate the second liquid from the tank through the heat exchanger and back into the tank.
Preferably, the liquid in the vat comprises milk. Preferably, the second liquid in the tank comprises water.
Preferably, the second flow path is external to the vat.
As can be appreciated from the above, the present invention diverges from known cooling systems in that pre-vat cooling need not be applied. The resulting isolation of the second flow path allows the cooling system of the invention to operate independently of fluid flow in the first flow path, thereby dispensing with the need one way for flow control valves in the second flow path. In addition, the specific construction of the cooling apparatus described above allows for ready inspection and cleaning of the apparatus, as compared with a known plate heat exchanger.
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patent: WO 98/15787 (1998-04-01), None
Jenkens & Gilchrist
Jiang Chen-Wen
McDermott Corrine
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