WO2015053692A1

WO2015053692A1 - Milk cooling tank and method of cooling milk

Info

Publication number: WO2015053692A1
Application number: PCT/SE2014/051159
Authority: WO
Inventors: Willem ALBERTS
Original assignee: Delaval Holding Ab
Priority date: 2013-10-07
Filing date: 2014-10-06
Publication date: 2015-04-16
Also published as: SE537535C2; SE1351183A1

Abstract

Herein a milk cooling tank (2) arranged to store milk at an animal milking site is disclosed. The milk cooling tank (2) comprises; a tank housing (4) provided with a milk storage space (18), a milk passage opening (20) in the tank housing (4) enabling passing of milk into and out of the milk storage space (18), and an evaporator (8). The milk cooling tank (2) comprises a cooling liquid passage (10) separate from the milk storage space (18). The cooling liquid passage (10) extends in thermal contact along a portion of the evaporator (8). Further, a method of cooling milk in connection with a milk cooling tank (2) is disclosed.

Description

Mi!k Cooling Tank and Method of Cooling Milk

TECHNICAL FIELD

The present invention relates to a milk cooling tank for storing milk at an animal milking site. The invention further relates to a method of cooling milk in connection with such a milk cooling tank.

BACKGROUND

At animal milking sites, milk has to be cooled over a certain period of time before milk is collected and transported to a dairy. Cooling of the milk is necessary in order for the milk quality not to deteriorate, in a milk cooling tank at an animal milking site, mi!k is stored at approximately 4 degrees Celsius.

At animal milking sites where at least one automatic milking station is used for the fully automated milking of milking animals, milk continuously flows, or intermittently flows wit comparatively short time intervals between milkings, into a milk cooling tank. This means that warm milk from the automatically milking station is continuously added to the milk cooling tank, at least for certain periods a day. The continuous addition of warm milk entails that at an inlet of the milk cooling tank it may be difficult to maintain a low temperature. For milk cooling tanks where the period between milk collections is in the range of 72 hours, this may create problems with bacteria growth.

To avoid or at least reduce bacteria growth, a so-called instant cooler, a heat exchanger such as a p!ate heat exchanger, for cooling milk with cold tap water may be arranged in the milk conduit leading from the milking station to the milk cooling tank. The milk arriving at the inlet of the milk cooling tank is thus already cooled to a lesser or greater extent.

There exists a need for an improved milk storing means where bacteria growth may be reduced.

SUMMARY

It is an object of the present invention to provide a milk cooling tank which is flexible and available for multiple tasks. According to an aspect of the invention, the object is achieved by a milk cooling tank arranged to store milk at an animal milking site, the milk cooling tank comprising: a tank housing provided with a miik storage space,

a milk passage opening in the tank housing enabling passing of milk into and out of the milk storage space, and

an evaporator adapted to evaporate therein a refrigerant in order to coo! milk in the miik storage space. The milk cooling tank comprises a cooling liquid passage separate from the milk storage space, the cooling liquid passage extending in thermal contact along a portion of the evaporator and being adapted to receive a cooling liquid to be cooled by the refrigerant.

Since the milk cooling tank comprises a cooling liquid passage extending in thermal contact along a portion of the evaporator, a cooling liquid may be produced in the cooling liquid passage readily available for cooling equipment external of the milk storage space. As a result, the above mentioned object is achieved.

It has been realised by the inventor that the evaporator of the milk cooling tank may be utilized for cooling a cooling liquid to be utilised in other equipment than the milk cooling tank itself, in particular, the cooling liquid may be utilised in a heat exchanger for cooling milk to be admitted into the storage space of the miik cooling tank. Thus, bacteria growth in the milk cooling tank may be reduced. The milk cooling tank may be adapted for use at an animal milking site comprising one or more automatic milking machines for the fully automated milking of milking animals. The milk cooling tank may thus be adapted to receive a continuous flow of milk and/or an intermittent flow of milk. Each milking may create a separate flow of milk to the milk cooling tank. In such intermittent flow of milk, an interval between two mi!kings may be within the range of seconds up to approximately an hour during daytime hours depending on the number of milking animals and the number of automatic milking machines. During night time hours the interval between two milkings may increase up to several hours. The milk cooling tank may be adapted for emptying at intervals of 48 hours, e.g. at intervals up to 72 hours. The cooling liquid passage being separate from the miik storage space means that the cooling liquid passage delimits a space separate from the milk storage space. That is, a liquid in the cooling liquid passage will not mix with a liquid in the milk storage space.

The milk cooling tank may be located in a room separate from animals in an animal holding area and separate from a milking area comprising a milking machine. The animal holding area ma be e.g. a barn or a pasture. At least one milk conduit from the automatic milking machine may lead to an inlet of the milk cooiing tank. A tank cleaning machine for automatic cleaning of the miik cooling tank may be provided in connection with the miik cooling tank. After emptying of the milk cooling tank, the tank cleaning machine is started and milk from the milking machine is not permitted to enter the mi!k cooling tank until the cleaning has finished.

According to embodiments, the cooling liquid passage may comprise a first connection point and a second connection point arranged accessible from an outer side of the tank housing and may be adapted to be connected to equipment to be cooied by a cooling liquid cooled in the cooling liquid passage, in this manner equipment utilizing a cooling liquid may be provided with cooling liquid from the milk cooling tank. Each of the first and second connection points may be provided with a connector means such as a threaded pipe end or a valve, but may also simply include a butt end of a pipe, to which butt end a connecting pipe may be welded, brazed, or crimped. According to embodiments, the evaporator may form part of a delimiting surface of the milk storage space in the tank housing, and the cooling liquid passage may be arranged on a non-milk contacting side of the evaporator. Alternatively, the evaporator may form part of a delimiting surface of the milk storage space in the tank housing, and the cooling liquid passage may be arranged on a milk contacting side of the evaporator.

According to embodiments, the milk cooling tank may comprise a pipe connector connected to the milk passage opening, the pipe connector comprising a milk inlet for connection to a milking machine of the animal milking site and a milk outlet adapted to be temporarily connected to a milk collection device when the milk cooling tank is to be emptied. The pipe connector may form a heat exchanger comprising a milk channel and a cooling liquid channel. The cooling liquid passage may be connected to the cooling liquid channel. In this manner a heat exchanger may be integrate with a miik inlet of the milk cooling tank and the milk flowing into the milk cooling tank ma be cooled upon entering the milk cooling tank. Thus, bacteria growth in the milk cooling tank may be reduced.

According to embodiments, the cooling liquid channel may comprise a cooling liquid pipe wound about a pipe body of the pipe connector.

According to other embodiments, the cooling liquid channel may be formed between a pipe body of the pipe connector and a wall element attached to the pipe body. According to embodiments the miik cooling tank may comprise a circulation pump connected to the cooling liquid passage and the cooling liquid channel. In this manner cooling liquid may be circulated between the cooling liquid passage in thermal contact with the evaporator and the cooling liquid channel to cool milk in the milk channel of the pipe connector.

It is a further object of the present invention to provide an alternative method of cooling milk in connection with a milk cooling tank.

According to an aspect of the invention, the further object is achieved by a method of cooling milk in connection with a milk cooling tank arranged to store milk at an animal milking site. The mi!k cooling tank comprises: A tank housing provided with a miik storage space and a milk passage opening in the tank housing, an evaporator, a cooling liquid passage separate from the miik storage space, the cooling liquid passage extending in thermal contact along a portion of the evaporator, and a pipe connector being connected to the milk passage opening. The pipe connector comprises a milk inlet for connection to a milking machine of the animal milking site and a miik outlet adapted to be temporarily connected to a milk collection device when the milk cooling tank is to be emptied. The pipe connector forms a heat exchanger comprising a milk channel and a cooling liquid channel. The milk cooling tank further comprises a circulation pump connected to the cooling liquid passage and the cooling liquid channel. The method comprises:

- evaporating a refrigerant in the evaporator to cooi milk in the milk storage space and to cool a cooling liquid in the cooling liquid passage, and

- circulating with the circulation pump a cooling liquid through the cooling liquid passage and the cooling liquid channel.

Since the cooling liquid is cooled in the cooling liquid passage in thermal contact with the evaporator and circulated through the cooling liquid passage and the cooling liquid channel of the pipe connector of the milk cooling tank, milk entering the pipe connector is cooled upon entering the milk cooling tank. As a result, the above mentioned object is achieved. Bacteria growth in the milk cooling tank may be reduced.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates a milk cooling tank according to embodiments.

Fig. 2 illustrates a cross section through a milk cooling tank according to embodiments, Figs. 3 and 4 illustrate a cross sections through a portions of a milk cooling tanks according to embodiments, and

Fig. 5 illustrates a method of cooling milk in connection with a milk cooling tank. DETAILED DESCRIPTION

Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 illustrates a milk cooling tank 2 according to embodiments. The milk cooling tank 2 is arranged to store milk at an animal milking site. The milk cooling tank 2 comprises a tank housing 4 provided with a milk storage space therein, A milk passage opening is arranged in the tank housing 4 enabling passing of milk into and out of the milk storage space. A pipe connector 6 is connected to the milk passage opening. The milk cooling tank 2 comprises an evaporator 8 adapted to evaporate therein a refrigerant in order to cool milk in the milk storage space. In a known manner a refrigerant circuit is formed by the evaporator 8 and non-shown compressor, condenser, and expansion device.

The milk storage space is delimited by the tank housing 4 and the evaporator 8. !n Fig. 1 portion of the tank housing 4 has been omitted to reveal a non-milk contacting side of the evaporator 8. The milk cooling tank 2 comprises a cooling liquid passage 10 separate from the milk storage space. The cooling liquid passage 10 extends in thermal contact along a portion of the evaporator 8. The cooling liquid passage 10 is adapted to receive a cooling liquid to be cooled by the refrigerant in the evaporator 8. Thus, a cooling liquid may be cooled in the cooling liquid passage, in these embodiments, the cooling liquid is utilised in an external heat exchanger 12 for cooling milk flowing from an end unit 14 of an automatic milking machine 16 to the miik cooling tank 2. The automatic milking machine 16 is connected to the pipe connector 6, The cooling liquid is circuiated through the cooling liquid passage 10 and the external exchanger 12. The milk from the automatic milking machine 16 is cooled by the cooling liquid, and the cooling liquid is heated by the milk, in the external exchanger 12. The heated cooling liquid is cooled in the cooling liquid passage 10 by the refrigerant evaporating in the evaporator 8. The milk cooling tank 2 is emptied at regular intervals. A milk collection device such as a milk collecting tank of a milk collecting truck from a dairy, is connected to the pipe connector 6 and the milk is transferred from the milk cooling tank 2 to the milk collection device.

As mentioned above, the evaporator 8 forms part of a delimiting surface of the milk storage space in the tank housing 4. In these embodiments the cooling liquid passage 10 is arranged on a non-milk contacting side of the evaporator 8.

Fig. 2 illustrates a cross section through a milk cooling tank 2 according to embodiments. Again, the milk cooling tank 2 comprises a tank housing 4 provided with a milk storage space 18. A milk passage opening 20 is arranged in the tank housing 4. A pipe connector 6 is connected to the tank housing 4 and the milk passage opening 20. The pipe connector 6 is adapted for connection of a milking machine and the empting of the milk cooling tank 2. The milk cooling tank 2 comprises an evaporator 8. The milk cooling tank 2 has an oval cross section, seen perpendicularly to the cross section shown in Fig. 2, and the evaporator 8 extends along a lower portion of the milk storage space 18 up to a level Indicated by a broken line 19.

The milk cooling tank 2 comprises a cooling liquid passage 10 separate from the milk storage space 18. The cooling liquid passage 10 extends in thermal contact along a portion of the evaporator 8. Again, the cooling liquid passage 10 is adapted to receive a cooling liquid to be cooled by the refrigerant in the evaporator 8. The evaporator 8 forms part of a delimiting surface of the milk storage space 18 in the tank housing 4. The cooling liquid passage 10 is arranged on a milk contacting side of the evaporator 8. A stirring device 21 for stirring milk in the milk storage space 18 is provided to prevent milk from freezing on a surface of the evaporator 8 in the milk storage space 18.

The cooling liquid passage 10 comprises a first connection point 22 and a second connection point arranged 24 accessible from an outer side of the tank housing 4. The first and second connection points 22, 24 are adapted to be connected to equipment to be cooled by a cooling liquid cooled in the cooling liquid passage 0. The equipment to be cooled may be e.g. an external heat exchanger as discussed in connection with Fig, 1 or a heat exchanger formed in the pipe connector 6 as discussed below with reference to embodiments disclosed in Figs. 3 or 4.

Fig, 3 illustrates a cross section through a portion of a milk cooiing tank 2 according to embodiments. The milk cooling tank 2 may be a miik cooiing tank as discussed in connection with Fig. 1 or Fig. 2. The miik cooling tank 2 comprises a pipe connector 6 connected to a milk passage opening 20. The pipe connector 6 illustrated is a t-pipe connector. The milk passage opening 20 is arranged in a tank housing 4 of the milk cooling tank 2. The pipe connector 6 comprises a miik in!et 26 for connection to a milking machine of an animal milking site, such as an automatic milking machine discussed in connection with Fig. 1. The pipe connector 6 further comprises a milk outlet 28 adapted to be temporarily connected to a milk collection device when the milk cooling tank is to be emptied. The milk collection device may be a milk collecting tank of a milk collecting truck. A removable lid 30 is provided to close the milk outlet 28. A flow path of milk flowing into the miik cooling tank 2 is indicated with wide arrows. A flow path of milk flowing out of the milk cooling tank 2 is indicated with broken wide arrows.

The pipe connector 6 forms a heat exchanger comprising a milk channel 32 and a cooling liquid channel 34. The cooiing liquid channel 34 is formed between a pipe body 36 of the pipe connector 6 and a wall element 38 attached to the pipe body 36. The cooiing liquid channel 34 extends around portions of the pipe body 36. The milk channel 32 is formed by an inferior of the pipe body 36. Connections pipes 40, 42 are provided for connecting the cooling liquid channel to a cooling liquid source. Suitably, the cooling liquid source is a cooling liquid passage 10 as discussed above in connection with Fig. 1 or Fig. 2. Arrows indicate the path of cooling liquid through the cooling liquid channel 34.

The milk cooling tank 2 comprises a circulation pump 43 connected to the cooling liquid passage 10 and the cooling liquid channel 34. Cooiing liquid is circulated by the circulation pump 43 betwee the cooling liquid passage 10 In thermal contact with the evaporator 8 of the miik cooiing tank 2 and the cooling liquid channel 34 to cool milk in the milk channel 32 of the pipe connector 6.

A control circuit 80 for controlling the circulation pump 43 is provided. The first temperature sensor 82 abuts against the pipe body 36 of the pipe connector 6. A second temperature sensor 84 is arranged in the cooling liquid channel 34. A controller 86 is connected to the first and second temperature sensors 82, 84 and the circulation pump 43. The controiier 86 is adapted to control the circulation pump 34 of cooling liquid utilising one or both of the first and second temperature sensors 82, 84. inter alia, the controller 86 is adapted to prevent freezing temperatures in the milk channel and 32.

Fig. 4 illustrates a cross section through a portion of a milk cooling tank 2 according to embodiments. The embodiments of Fig. 4 are similar to those of Fig. 3. Again, a pipe connector 6 forms a heat exchanger comprising a mi!k channel 32 and a cooling liquid channel 34. Only the main differences between the Fig. 3 and Fig. 4 embodiments will be discussed in the following. The cooling liquid channel 34 comprises a cooling liquid pipe 44 wound about a pipe body 36 of the pipe connector 6. Again, connections pipes 40, 42 are provided for connecting the cooling liquid channel 34 to a cooling liquid source such as a cooling liquid passage as discussed above in connection with Fig. 1 , Fig. 2 or Fig. 3. Again, arrows Indicate the path of cooling liquid through the cooling liquid channel 34.

Illustrated in these embodiments are also two valves arranged in the connector pipe 6, An outlet valve 46 is provided at the milk outlet 28 and a service vaive 48 is provided at the milk passage opening 20. The outlet valve 46 is provided for the lid 30 to be removed from the pipe connector 6 when the milk cooling tank 2 is to be emptied. The outlet valve 46 is not opened until the milk collection device has been connected to the milk outlet 8 of the pipe connector 6. The service valve 48 is provided for closing the milk passage opening 20 for instance, if access is to be gained to an interior of the pipe connector 6 or if a connection to the milk inlet 26 is to be opened or removed, while the milk cooling tank 2 is filled with milk. Fig. 5 illustrates a method of cooling milk in connection with a milk cooling tank arranged to store milk at an animal milking site. The milk cooling tank suitably is a milk cooling tank 2 according to any aspect or embodiment discussed herein comprising an evaporator, a milk storage space, a cooling liquid passage extending in thermal contact along a portion of the evaporator, a pipe connector forming a heat exchanger comprising a miik channel and a cooling liquid channel, and a circulation pump connected to the cooling liquid passage and the cooling liquid channel. The method comprises:

- evaporating 100 a refrigerant in the evaporator to cool milk i the milk storage space and to cool a cooling liquid in the cooling liquid passage, and

- circulating 102 with the circulation pump a cooling liquid through the cooling liquid passage and the cooling liquid channel. According to embodiments, the method may comprise:

- stopping 104 the eircuiating 102 when a temperature of the pipe connector falls below a first threshold temperature value. The first threshold temperature value may be for instance 0.5°C, c, or 2°C. In this manner freezing of mi!k in the connector pipe may be avoided. The first threshold temperature value may be sensed by a temperature sensor abutting against the pipe connector. The temperature sensor is connected to a control circuit for the circulation pump.

According to embodiments, the method may comprise:

- stopping 106 the circulating 102 while a temperature of the cooling liquid is below a second threshold temperature value. The second threshold temperature value may be for instance 0"C, TO, or 2°C. In this manner freezing of milk in the connector pipe may be avoided. The second threshold temperature value may be sensed by a temperature sensor arranged at or in the cooling liquid channel. The temperature sensor is connected to a control circuit for the circulation pump.

This invention should not be construed as limited to the embodiments set forth herein. A person skilled in the art will realize that different features of the embodiments disclosed herein may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims, it is also understood by those skilled in the art that the cooling liquid passage extending in thermal contact along a portion of the evaporator may comprise a pipe or may be formed between a wail element and the evaporator. The cooling liquid may be water containing glycol to prevent freezing of the water. A suitable amount of cooling liquid circulating in the cooling liquid passage 10 and the cooling liquid channel 34 may be about 10 - 20 litres. A suitable volume of the cooiing liquid passage 10 in thermal contact along a portion of the evaporator 8 may then be about 7 - 15 litres. The milk cooling tank 2 may have a volume of 6000 litres per automatic milking machine supplying milk to the milk cooling tank 2. Such a volume may suffice for a 72 hour emptying interval of the milk cooling tank 2.

Although the invention has been described with reference to example embodiments, many different alterations, modifications and the like will become apparent for those skilled in the art. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions or groups thereof.

Claims

1 . A milk cooling tank (2) arranged to store milk at an animal milking site, the milk cooling tank (2) comprising:

a tank housing (4) provided with a mi!k storage space (18),

a milk passage opening (20) in the tank housing (4) enabling passing of milk into and out of the milk storage space (18), and

an evaporator (8) adapted to evaporate therein a refrigerant in order to cool milk in the miik storage space (18),

characterised in that the miik cooling tank (2) comprises a cooling liquid passage (10) separate from the milk storage space (18), the cooling liquid passage (10) extending in thermal contact along a portion of the evaporator (8) and being adapted to receive a cooling liquid to be cooled by the refrigerant.

2. The milk cooling tank (2) according to claim 1 , wherein the cooling liquid passage (10) comprises a first connection point (22) and a second connection point (24) arranged accessible from an outer side of the tank housing (4) and adapted to be connected to equipment to be cooled by a cooling liquid cooled in the cooling liquid passage (10).

3. The milk cooling tank (2) according to claim 1 or 2, wherein the evaporator (8) forms part of a delimiting surface of the milk storage space ( 8) in the tank housing (4), and wherein the cooling liquid passage (10) is arranged on a non-milk contacting side of the evaporator (8).

4. The milk cooling tank (2) according to claim 1 or 2, wherein the evaporator (8) forms part of a delimiting surface of the milk storage space (18) in the tank housing (4), and wherein the cooling liquid passage (10) is arranged on a milk contacting side of the evaporator (8).

5. The milk cooling tank (2) according to any one of the preceding claims, comprising a pipe connector (6) connected to the milk passage opening (20), the pipe connector (6) comprising a miik inlet (26) for connection to a milking machine of the animal milking site and a milk outlet (28) adapted to be temporarily connected to a milk collection device when the milk cooling tank (2) is to be emptied, wherein the pipe connector (6) forms a heat exchanger comprising a milk channel (32) and a cooling liquid channel (34), and wherein the cooling liquid passage (10) is connected to the cooling liquid channel (34).

6. The milk cooling tank (2) according to claim 5, wherein the cooling liquid channel (34) comprises a cooling liquid pipe (44) wound about a pipe body (36) of the pipe connector (6).

7. The mi!k cooling tank (2) according to claim 5, wherein the cooling liquid channel (34) is formed between a pipe body (36) of the pipe connector (6) and a wall element (38) attached to the pipe body (36).

8. The milk cooling tank (2) according to any one of claims 5 - 7, comprising a circulation pump (43) connected to the cooling liquid passage (10) and the cooling liquid channel (34).

9. A method of cooling milk in connection with a milk cooling tank (2) arranged to store milk at an animal milking site, the milk cooling tank (2) comprising:

a tank housing (4) provided with a milk storage space (18) and a milk passage opening (20) in the tank housing (4), an evaporator (8), a cooling liquid passage (10) separate from the milk storage space (18), the cooling liquid passage (10) extending in thermal contact along a portion of the evaporator (8), and a pipe connector (6) being connected to the milk passage opening (20), the pipe connector (6) comprising a milk inlet for connection to a milking machine of the animal milking site and a milk outlet adapted to be temporarily connected to a milk collection device when the milk cooling tank (2) is to be emptied, wherein the pipe connector (6) forms a heat exchanger comprising a milk channel (32) and a cooling liquid channel (34), the milk cooling tank (2) further comprising a circulation pump (43) connected to the cooling liquid passage (10) and the cooling liquid channel (34), wherein the method comprises:

- evaporating (100) a refrigerant in the evaporator (8) to cool milk in the milk storage space (18) and to cool a cooling liquid in the cooling liquid passage (10), and

- circulating (102) with the circulation pump (43) a cooling liquid through the cooling liquid passage (10) and the cooling liquid channel (34).

10. The method according to claim 9, comprising:

- stopping ( 04) the circulating (102) when a temperature of the pipe connector (6) fails below a first threshold temperature value.

11. The method according to claim 9 or 10, comprising:

- stopping (1.06) the circulating (102) while a temperature of the cooling liquid is below a second threshold temperature value.