GB2136102A - Milk cooler - Google Patents

Abstract

This invention relates to milk coolers and comprises a container 18 into which is fitted a cooling coil 20. The container has a milk inlet 12 and an outlet 15A, the latter of which is connected to a source of vacuum. A further vacuum source 21 is introduced into the container above the outlet so that once milk is introduced into the vessel there are oppositely acting vacuum forces on the milk and the flow of milk into the outlet is restricted. Means 23 are provided for closing the further vacuum source 21 whenever the level of milk reaches a predetermined level, and hence efficient cooling is achieved. <IMAGE>

Description

SPECIFICATION Improvements in or relating to liquid coolers This invention relates to liquid coolers and in particular, but not exclusively, to milk coolers.

It is desirable to precool milk before it is delivered into a bulk milk tank so that the hot milk does not raise the temperature of the milk already in the tank and to avoid related health hazards.

However, the whole concept of milking machines is to provide a pulsed vacuum in the teat cups and hence an intermitent flow of milk. This presents problems for cooling the milk efficiently and to date it is generally done by trickling the milk over a cooled corrugated surface. This arrangement is neither efficient nor hygienic.

It is an object of this invention to provide an improved liquid cooler.

From one aspect the invention consists in a liquid cooler comprising a vessel, a liquid inlet, a liquid outlet, a heat exchanger in the vessel for cooling the liquid, and means for restricting a flow of liquid from the outlet whenever the liquid in the vessel falls below a pre-determined level.

In a preferred embodiment the level is that at which at least the working part of the heat exchanger is covered and is below the top of the vessel.

The restricting means may include a source of vacuum disposed above the predetermined level and acting in a sense to prevent or reduce the flow of liquid from the outlet. The restricting means may further comprise a valve for closing the vacuum source whenever the liquid reaches the predetermined level, in which case the valve may be operated by the level sensor.

The source of vacuum may include an outlet disposed in the vessel in which case the restricting means may comprise a valve float for floating on the liquid to close off the outlet when the liquid rises to the predetermined level. Conveniently, the vacuum outlet may comprise a peripheral aperture in a pipe extending into the vessel and the float valve may encircle the pipe. Lock means may be provided for retaining the float valve in its closed position.

In an alternative arrangement the cooler may include a level sensor and means for rendering the source of vacuum inoperative when the sensor detects a predetermined level of liquid in the vessel.

In any of these arrangements the liquid outlet may be connected to the vacuum source and may be defined in a common pipe with the source of vacuum of the restricting means; the common pipe extending downwardly into the vessel.

Alternatively the liquid outlet and the source of vacuum of the restricting means may be connected to a common vacuum source.

From another aspect the invention comprises a liquid container comprising a vessel having an inlet and an outlet and having a vacuum source for acting on liquid within the vessel to limit the rate of flow of liquid through the outlet and means for reducing the strength of the source such that liquid can flow freely through the outlet.

The invention may be performed in a variety of ways and a specific embodiment will now be described with reference to the accompanying drawing, which is a diagrammatic view of part of a milking system including the cooler of the invention.

A milking system generally indicated at 10, has a number of clusters (one of which is indicated at 11) which are connected to a milk pipe 12 via a manifold 1 3. The milk pipe 12 enters the top of a milk cooler 14 which is itself connected to a separator 1 5 by an outlet pipe 15A. The separator 1 5 is connected at its lower end to its bulk tank (not shown) by the pump 16 and at its upper end to a vacuum source (not shown) by pipe 17.

The milk cooler 14 comprises a cylindrical reservoir 18, having a lid 19, and a heat exchanger 20. The outlet pipe 1 5A extends from a point just above the bottom of the reservoir 18 upwardly through the centre of the coil of the heat exchanger 20 and through the lid 19.

The outlet pipe 15A is provided with peripheral perforations 21 above the top of the coil of the heat exchanger 20. An annular float 22 encircles the outlet pipe 15A and has an upstanding collar 23 dimensioned to close off the perforations 21 when the float 22 reaches a predetermined level in the reservoir 1 8.

The float 22 is provided with an annular seat 24 to prevent it dropping to the bottom of the reservoir 18 and has an associated latch 24 mounted in the lid 19 for engaging a radial flange 23A on the collar 23 to lock the float in the position in which it closes off perforations 21.

In use the vacuum source (not shown) is switched on and a pulsed suction passes through the separator 15, outlet pipe 15A, reservoir 18, milk pipe 12 and manifold 13 to the clusters 11.

As milk is drawn off by each cluster it passes into the reservoir 1 8. Because the milk entering the reservoir 18 experiences opposed suctions, from the outlet formed at the bottom of outlet pipe 1 5a and through the performations 21, little or no milk is drawn into the outlet pipe 15A and thus the level of milk in the reservoir quickly rises to cover the coil 20A of the heat exchanger 20. As the reservoir is filling up the milk at the bottom is being cooled and is already at an acceptable temperature by the time the coil 20A is covered.

When the milk rises a little above this level it lifts the float 22 off the seat 24 until the collar 23 covers the perforations 21. At this moment the secondary vacuum source is removed from the reservoir 1 8 and milk can readily be drawn up the outlet pipe 15A into the separator 1 5. As this milk is taken from the bottom of the reservoir 1 5 it is already cooled to the desired temperature.

Once the level of milk falls as a result of the withdrawal of the cold milk the float drops down again revealing the perforations 21 and hence restricting the flow of milk into the outlet pipe 15A. The cooler operates in this cycle many times during milking, always ensuring that the milk is properly cooled before it is withdrawn into the separator.

When milking comes to an end the milk is left in the cooler 18 for sufficient time for all of it to be properly cooled and the flaot is then caught by latch 24 and locked into the position in which it closes off perforations 21. The whole cooler 14 can then be emptied into the separator 1 5. As is well known milk entering separator 1 5 is pumped to the bulk tank (not shown) by pump 16.

Claims (17)

1. A liquid cooler comprising a vessel, a liquid inlet, a liquid outlet, a heat exchanger in the vessel for cooling the liquid, and means for restricting a flow of liquid from the outlet whenever the liquid in the vessel falls below a pre-determined level.

2. A cooler as claimed in Claim 1, wherein the level is that at which at least the working part of the heat exchanger is covered.

3. A cooler as claimed in Claim 1 or 2, wherein the level is below the top of the vessel.

4. A cooler as claimed in any one of the preceding claims wherein the restricting means include a source of vacuum disposed above the pre-determined level and acting in a sense to prevent or reduce the flow of liquid from the outlet.

5. A cooler as claimed in Claim 4 wherein the restricting means further comprises a valve for closing the vacuum source whenever the liquid reaches the pre-determined level.

6. A cooler as claimed in Claim 5, wherein the valve is operated by a level sensor.

7. A cooler as claimed in Claim 4, wherein the source of vacuum includes an outlet disposed in the vessel.

8. A cooler as claimed in Claim 7 wherein the restricting means further comprises a valve float for floating on the liquid to close off the outlet when the liquid rises to the pre-determined level.

9. A cooler as claimed in Claim 8 wherein the vacuum outlet comprises a peripheral aperture in a pipe extending into the vessel and wherein the float valve encircles the pipe.

10. A cooler as claimed in Claim 8 or Claim 9 further comprising lock means for retaining the float valve in its closed position.

11. A cooler as claimed in Claim 4 further comprising a level sensor and means for rendering the source of vacuum inoperative when the sensor detects a pre-determined level of liquid in the vessel.

12. A cooler as claimed in any one of the Claims 4 to 11 wherein the liquid outlet is connected to a vacuum source and is disposed below the pre-determined level.

13. A cooler as claimed in Claim 12 wherein the liquid outlet and the source of vacuum of the restricting means are formed in a common pipe extending downwardly into the vessel.

14. A cooler as claimed in Claim 12 wherein the liquid outlet and the source of vacuum of the restricting means are connected to a common vacuum source.

1 5. A liquid container comprising a vessel having an inlet and an outlet and having a vacuum source for acting on liquid within the vessel to limit the rate of flow of liquid through the outlet and means for reducing the strength of the source such that liquid can flow freely through the outlet.

16. A milking machine incorporating a cooler as claimed in any one of the preceding claims.

17. A milking machine as claimed in Claim 16 wherein the cooler is upstream of the dairy collector.