GB1580742A

GB1580742A - Immersion cooler for cooling milk or other liquids

Info

Publication number: GB1580742A
Application number: GB1768277A
Authority: GB
Original assignee: Westfalia Separator GmbH
Current assignee: GEA Mechanical Equipment GmbH
Priority date: 1976-05-06
Filing date: 1977-04-27
Publication date: 1980-12-03
Also published as: FR2350560A1; FR2350560B1; DE2620024A1; DE2620024C3; CH614105A5; AT349502B; ATA215977A; NL7704817A; DE2620024B2; IE45137B1; IE45137L

Abstract

An agitating mechanism which can be immersed in a cooling tank and is driven via a shaft by a motor arranged outside the tank has an immersion body with inner and outer evaporators (5, 6) which are designed as double hollow cylinders. The outer evaporator (6) surrounds the inner evaporator (5) and the agitating mechanism (1, 2) situated below the latter, at a distance from them both. The inner evaporator (5) is connected to the feed pipe (9) and the outer evaporator (6) is connected to the discharging pipe for the refrigerating agent. The spaces (12, 13) formed by the evaporators (5, 6) are axially permeated by the liquid and permit even and intensive cooling, it being possible to maintain, for a given cooling surface, the low height of the immersion cooler which is desired so that the liquid can be treated in a gentle manner. <IMAGE>

Description

(54) IMMERSION COOLER FOR COOLING MILK OR OTHER LIQUIDS (71) We, WESTFALIA SEPARATOR AG, A German Body Corporate, of, 4740 Oelde 1/Westfalen, Postfach 2420, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to an immersion cooler for cooling milk or other liquids in a milk or other container, comprising a stirrer which can be immersed in the milk, which via a shaft is rigidly connected to a motor located in use, above the milk and produces an axial flow of the milk, an evaporator comprising a double walled cylinder, said evaporator being spaced from and freely surrounding the drive shaft of stirrer and at least partly immersible in the milk and being connected via a feed line, e. g. for the liquid refrigerating agent and a drain line for the refrigerating agent vapour with a refrigerating unit located outside the milk container.

An immersion cooler of this type is for example known from DOS 1,501,170. In immersion coolers of this type, the stirring apparatus is constructed with a propeller stirrer, in which the blades of the stirrer propeller are so crossed or given such a pitch that they convey axially upward the entrained milk within the cylindrical evaporator, and guide plates are fitted in longitudinally directed manner on the inside of the evaporator and inhibit the rotary movement of the milk.

The milk flowing out of the chamber formed within the inner of the double walls of the evaporator passes into the chamber between the inner wall of the container and the outer wall of the evaporator, whereby the continual circulation of the milk past the inner and outer cooling surface of the evaporator leads to a heat exchange between the milk and the refrigerating agent and a uniform distribution of the milk fat in the milk, whilst preventing creaming of the milk.

However, it has been found to be a disadvantage of such immersion coolers that although due to the greater turbulence there is a good heat exchange on the inside of the evaporator, this heat exchange becomes increasingly ineffective on the outside of the evaporator with the increasing diameter of the milk container, because there is a constant reduction in the speed and consequently the turbulence of the circulated milk on the outside of the evaporator with increasing distance from the inner wall of the container. This leads to a poorer heat exchange in the evaporator, so that undesired icing of the outside of the evaporator occurs. For example, non-evaporating refrigerating agent can enter the refrigerating unit compressor and produces harmful water hammer in the compressor cylinder.

To obviate these disadvantages, DOS 2, 147,959 proposes an immersion cooler with a flow guide mechanism, in which the evaporator is provided with a spacedly surrounding cylindrical guide surface, so that the milk to be cooled initially necessarily flows along the outer surface of the evaporator and is subsequently axially pumped by means of a propeller stirrer through the hollow cylinder of the evaporator. However, the necessarily powerful pumping action of the propeller leads to a very powerful suction action between evaporator and cylindrical guide surface, so that the milk rising within the evaporator and passing over the edge of said evaporator is immediately supplied between evaporator and cylindrical guide surface in circulation to the propeller stirrer, thereby counteracting a continuous good mixing of the cooled and uncooled milk. The cooling time is unnecessarily increased and the structure of the milk is unnecessarily damaged.

Evaporators of the known immersion coolers either have a large overall height with a small internal diameter of a very limited overall height with a large internal diameter.

In order to obtain the necessary pressure head of the milk in the taller evaporators, particularly when the containers are only partly filled with milk, it is either necessary to increase the diameter or the pitch of the propeller stirrer in the case of constant motor speed. On the one hand, this requires more power and on the other the milk is churned to such an extent that there is danger of butter grains forming in the milk. Furthermore, on reaching the upper edge of the evaporator, the milk is centrifuged outwards and with increasing height thereof and limited filling of the container it falls very heavily onto the surface of the milk in the chamber beneath the evaporator to produce aTr pockets.

In the case of a larger internal diameter of the evaporator on the one hand large propellers are necessary which also require more power and on the other considerable difficulties are caused by the distribution of milk on the inner surface of the evaporator. It has bcen found that it is more advantageous to use evaporators with a lower overall height.

The problem of the invention is to provide an immersion cooler with a constant cooling surface, reduced overall height and improved efficiency.

It is based on the fundamental principle that for maintaining the natural structure of the milk fat in the milk and to avoid formation of butter grains, a small diameter and reduced pitch of the propeller stirrer are desired, so that a low overall height of the evaporator is necessary.

According to the present invention an immersion cooler for cooling milk or other liquids in a milk or other container comprises a stirrer which can be immersed in milk. which via a shaft is rigidly connected to a motor located in use, above the milk and ada-d to produce an axial flow of the milk, an evaporator comprising a double walled cylinder the evaporator being spaced from and surrounding the drive shaft of the stirrer and at least partly immersible in the milk and being connected via a feed line, e. g. for a liquid refrigerating agent and a drain line for the refrigerating agent vapour with a refrigerating unit located outside the container, in which the cooling surface of the immersion cooler is divided into an inner evaporator and an outer evaporator each constructed in the form of a double walled cylinder, the inner evaporator and the stirrer being spacedly surrounded by the outer evaporator, both evaporators communicat mg with one another bv tubes and the feed line for the liquid refrigerating agent being connected with the inner evaporator and the drain line for the refigerating agent vapour being connected with the outer evaporator and the stirrer being arranged below the inner evaporator and within the outer evaporator so that it produces an axial flow of the milk through the chambers bounded by the evaporators.

The subdividing of the cooling surface of the immersion cooler into two seriesarranged evaporators and the resulting low overall height considerably increases the exchange surface in the turbulent inner zone produced by the propeller stirrer thus improving both the evaporation of the refrigerating agent and the efficiency of the immersion cooler.

The invention may be performed in various ways and one specific embodiment will now be described by way of example with reference to the accompanying drawing which is an elevation of an immersion cooler according to the present invention.

In the drawing a stirrer shaft 1 and a stirrer propeller 2 are rigidly connected to and driven by a motor 4 fixed to a plate 3.

The stirrer shaft is surrounded by an evaporator 5 constructed as a double walled cylinder which, according to the invention is spacedly surrounded by a further evaporator 6 constructed as a double walled cylinder.

The two evaporators are interconnected by means of tubes 7. The stirrer propeller 2 is arranged below the inner evaporator 5 and the outer evaporator 6 extends below the inner evaporator and surrounds the propeller stirrer. A ribbed guide member 8 is arranged above the propeller stirrer and beneath the inner evaporator and serves for mounting shaft 1 and and to guide the milk and inhibit axial rotation thereof.

The inner evaporator 5 is connected with a feed line 9 for a liquid refrigerating agent and the outer evaporator 6 with a drain line tO for the refrigerating unit (not shown).

For centering the evaporator relative to the drive shaft and the propeller, the outer evaporator 6 is connected with plate 3 by means of a support 11.

Immersion coolers of this type can be used not only for cooling milk but also for cooling other liquids.

Claims

WHAT WE CLAIM IS : 1. An immersion cooler for cooling milk or other liquids in a milk or other container. comprising a stirrer which can be immersed in the milk, which via a shaft is rigidly connected to a motor located in use above the milk and adapted to produce an axial flow of the milk, an evaporator comprising a doux-ive walled cylinder the evaporator being spaced from and surrounding the drive shaft of the stirrer and at least partly immersible in the milk, and being connected via a feed line e. c. for a liquid refrigerating agent and a drain for refrigerating agent vapour with a refrigerat- ing unit located outside the container, in which the cooling surface of the immersion cooler is divided into an inner evaporator