GB2484351A

GB2484351A - Cooling milk

Info

Publication number: GB2484351A
Application number: GB1017062.9A
Authority: GB
Inventors: Philip Guest; Lee Page; Trevor Taylor; Christopher Strutt
Original assignee: DAIRY GREEN Ltd
Current assignee: DAIRY GREEN Ltd
Priority date: 2010-10-09
Filing date: 2010-10-09
Publication date: 2012-04-11
Also published as: GB201017062D0

Abstract

Apparatus and method for cooling milk from cows, sheep or goats in a milking parlour. The milk is passed directly to a heat pump 10 where heat is removed and transferred to water 11 to produce either warm or hot water for use elsewhere in the milk production process. The milk is cooled from the animal's body temperature (about 37Â°C) to nominally 4Â°C, suitable for storage 7 until transferred to a dairy 9 for further processing. The heat pump has multiple settings allowing production of either warm water, e.g. about 55Â°C, or hot water, e.g. up to 80Â°C. The warm water is used for lactating cows to drink, so increasing their milk yields, and / or for mixing with milk and feeding to calves. The hot water is used for sterilising the milk production apparatus. Either / both warm or / and hot water may be used for space heating, under floor heating or keeping access areas ice-free in winter. A controller monitors the milk production, its cooling and whether warm or hot water is produced. Additional chilling of the milk may be provided, if required, as may additional heating, if the temperature of the hot water is insufficient for sterilisation purposes.

Description

COOLING MILK

This specification relates to the cooling of milk directly from cows, goats or sheep, etc. as they are being milked on the farm to reduce it to a temperature appropriate for bulk storage until it is further processed on the farm or taken away to a Dairy for processing there.

Cows, goats and sheep, etc. are warm blooded and, when lactating, the milk in their udders is at body temperature so that it is palatable for their young to drink. For this specification, the description will be written on the basis of cows and cow's milk, as this is the most widely used milk, but the teaching applies equally well to milk from goats, sheep or other mammals. The cow's body temperature will be assumed to be 37°C.

Current practice in farms (Fig. 1, Prior Art) is to pass the milk 2 from the cow in the milking parlour I (at a temperature of 37°C) directly 6 to insulated, refrigerated tank 7 where it is is cooled to 4°C. Optionally, a plate cooler 3 (shown dashed) is used between parlour I and tank 7 to pre-cool milk 2, using water 5 at 8-9°C. The cold milk is retained in tank 7 until it is collected, usually on a daily basis, by refrigerated tanker 8 and taken to a dairy 9.

The present invention is to place a heat pump 10 (Fig. 2) in pipeline 2, 6 between parlour 1 and tank 7 and cool the milk down to 4°C much more quickly and efficiently than could be achieved either by refrigerated tank 7 alone or in conjunction with pre-cooler 3. The greater efficiency of heat pump 10 will reduce electricity consumption compared to that used by refrigerator 7. I-teat pump 10 will also produce heated water as a by-product.

Milk production is highly competitive and operates on very small margins, so, with the exception of a few specialist producers, requires large-scale units to be economic. Clearly large-scale units have high overall capital and running 4 costs but do also have opportunities to justify investment in new equipment to reduce net energy bills. Thus, there is a need for cost-effective means to reduce overall energy consumption in milk production facilities (Fig. 1).

According to the invention, there is provided apparatus for chilling milk on continuous basis comprising a heat pump to cool the milk and produce heated water for use elsewhere in the milk production facility.

According to a first variation of the apparatus of the invention, the milk comes from any lactating animal(s).

According to a second variation of the apparatus of the invention, the lactating animals are cows, goats or sheep.

According to a third variation of the apparatus of the invention, the milk is passed directly from the animals being milked to the milk chilling heat pump.

According to a fourth variation of the apparatus of the invention, the heat pump removes heat from the milk at body temperature and transfers it to water, raising its temperature.

According to a fifth variation of the apparatus of the invention, the water is mains water.

According to a sixth variation of the apparatus of the invention, the water from the heat pump is warm and suitable for cows to drink and / or for mixing with milk for calves to drink.

According to a seventh variation of the apparatus of the invention, the water from the heat pump is hot water suitable for sterilising apparatus.

According to an eighth variation of the apparatus of the invention, the water from the heat pump is used either directly or indirectly for heating.

According to a ninth variation of the apparatus of the invention, the heating is underfloor heating.

According to a tenth variation of the apparatus of the invention, the heating is space heating.

According to an eleventh variation of the apparatus of the invention, the warm water and hot water is stored in different tanks.

According to a twelfth variation of the apparatus of the invention, the heat pump has separate settings to produce either warm water or hot water, as required.

According to a thirteenth variation of the apparatus of the invention, the hot water is used for sterilisation of the milk production equipment.

According to a fourteenth variation of the apparatus of the invention, the warm or hot water is used to keep access areas ice-free.

According to a fifteenth variation of the apparatus of the invention, a controller is provided S with means to a monitor parameter(s) of the output(s) of the heat pump against predetermined value(s) and to take remedial action when the monitored parameter(s) deviate from the preset value(s).

According to a sixteenth variation of the apparatus of the invention, the remedial action involves control of a valve(s) in a flow line(s).

According to a seventeenth variation of the apparatus of the invention, the remedial action involves control of the compressor in the heat pump.

According to an eighteenth variation of the apparatus of the invention, the remedial action involves providing additional chilling.

According to a nineteenth variation of the apparatus of the invention, the remedial action involves providing additional heating.

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According to the invention, there is provided a method for chilling milk on continuous basis comprising:-i) providing a milking parlour where lactating animals are milked,ihe milk being at the animals' body temperature; ii) passing the milk from the parlour to a heat pump; iii) cooing the milk in the heat pump and extracting heat therefrom; iv) passing the cooled milk to a storage means for immediate, or subsequent, processing; v) using the heat extracted from the milk to produce heated water; characterised in that the heated water has a temperature higher than that of the body temperature of the animals being milked and that the heated water and / or heat in the heated water is used elsewhere in / around the milk production facility.

According to a first variation of the method of the invention, the milk is cooled to a temperature suitable for an extended period of storage, without there being significant deterioration of its condition. It According to a second variation of the method of the invention, the heat pump is used to produce both warm water for drinking and hotter water for use sterilising the milk production equipment.

S According to a third variation of the method of the invention, the warm water is fed to lactating cattle and / or mixed with milk and fed to calves.

According to a fourth variation of the method of the invention, the holler water is used, either directly or with additional heating, to sterilise the milk production equipment.

According to a fifth variation of the method of the invention, the heated water is used for space heating.

According to a sixth variation of the method of the invention, the heated water is used for keeping access areas frost / ice free.

In a preferred application of the invention, the heat pUmp is located in a milk production facility, taking milk directly from the animals / cows in the milking parlour and is used to cool the milk from the animals' / cows' body temperature down to the milk storage temperature so that it can be passed to an insulated storage tank. The heat in the milk is used to warm water, producing either warm water for drinking by the cows or calves or hot water to sterilise the milk production equipment. Alternatively, the heat may be used for space heating or de-icing access areas, adjacent to the milk production facility.

The apparatus of the invention may be controlled automatically, with separate settings for producing the warm or hot water, as required.

For a clearer understanding of the invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the following drawings in which:-Figure 1 is a block diagram of a current milk production process (Prior Art); Figure 2 is a block diagram of the milk production process, according to the invention; and Figure 3 is a block diagram of the principle of the heat pump, according to the invention.

In the following description, the same reference numeral is used for identical components in different Figures or for different components fulfilling identical functions.

Before commencing the description, it is necessary to understand the difference between heat and temperature. The thermodynamic term for heat is enthalpy, which is the total amount of heat in a body or system. Thus, the enthalpy of a large body at a low temperature may actually be greater than that of a smaller body at a higher temperature.

This is the principle on which a heat pump operates, i.e. taking low temperature heat from a large body and converting it to higher temperature heat in a smaller body. Clearly, the Laws of Thermodynamics and principle of conservation of energy apply as does the efficiency of the items forming the heat pump.

Referring to Fig. 2, cow I is used to indicate a milking parlour; though only a single cow 1.

is shown, this represents a herd of cows, with animals being milked together in groups and the milking taking place over a period of (usually) hours. Cows are normally milked twice a day, with their milk being fed via a pipe 2 to heat pump 10. Heat pump 10 is powered by mains 4 and draws water 11, e.g. from the mains, warms it and discharges it into pipe 12.

The cooled milk passes 6A to storage tank 7. A standby chiller 3A is provided (shown dashed), connected 3B, 3C to pipe 6A, so that by if heat pump 10 is not able to cool the milk to the required temperature, the milk 6 may be diverted 3B through chiller 3A, via valves (not shown). Storage tank 7 would be insulated and provided with a refrigeration means (not shown). Though cows 1 are normally milked twice a day, the road tanker collecting the milk and taking it 8 to dairy 9 usually calls only once a day, so that means of keeping the milk cold 7 is essential.

The heated water 12 may be either warm water 13 at, say, 55°C, sent to a first storage tank (not shown) or hot water 14 at, say 80°C, sent to a second storage tank (not shown).

Either of these sources 13 or 14 may be used for space heating, whether via underfloor piping or via conventional radiators. Areas to be heated would be, for example, where newborn calves are kept or, perhaps, external access paths subject to ice during winter.

Cows I prefer to drink warm (e.g. 40-45°C) water 13 rather than cold mains water 11 and they will drink more of it, leading to an increased milk yield. This is only really practical in winter, when the cattle are indoors, but, as the increase in yield can be as much as 10%, it is a valuable addition. Warm water may also be provided before, during or after milking, so that some of this benefit will be available throughout the year. The hot (e.g. 80°C) water is used for sterilising the udder cups (not shown) and piping 2, 6A, 3A, 3B and 3C after every milking. Tank 7 may be sterilised, when empty.

The principle of a heat pump is shown in Fig. 3; it uses the Carnot Thermodynamic Cycle, which is also used in refrigerators. Pump 17 compresses the cool, working fluid from pipe 23 and passes it, as a hot gas, intb pipe 20. The input of energy raises the temperature of the working fluid and, in heat exchanger 18, the hot working fluid passes heat into cold S water 11, which leaves as hot water 12. The cooling of high pressure gas 20 causes it to condense, giving up latent heat to water 11, heating it 12. The working fluid in pipe 21 is now a cool, high pressure liquid. This liquid is expanded adiabatically through valve 19, causing it to cool in a stepwise manner with the temperature dropping by several tens of degrees Centigrade almost instantaneously. The cold, low pressure liquid flows along pipe 22 to a second heat exchanger 16 where it gains heat from the warm milk 2, causing it to evaporate as it gains both sensible heat and latent heat from milk 2. In heat exchange 16, the warm milk 2 is cooled 6A and the cold liquid working fluid evaporated to become a cool gas, which flows along pipe 23 back to compressor 17 to restart the whole cycle again.

Controller 25 monitors and controls the operation of heat pump 10. A temperature / Indictor I Controller 26 monitors the temperature of cooled milk 6A and adjusts 27A the flowrate via valve 28, under the guidance 27 of controller 25. To accommodate variations in flow 6A, a buffer tank (not shown) may be incorporated in pipe 2. If heat pump 10 could not maintain the required temperature of milk 6A, controller 25 will bring standby chiller 3A into operation via a control linkage (not shown). This may be on either a continuous or intermittent basis, as required.

Similarly, temperature / indicator / controller 29 monitors and controls the output temperature of water 12 and maintains it 30A as required 13, or 14 or 15 via valve 31, under the guidance 30 of controller 25. With at least two potential water output requirements 13, 14 and 15, heat pump 10 can be provided with appropriate modes of operation, via means 32 and I or 33 controlling the settings 19A of expansion valve 19 and / or the speed of the motor (not shown) driving compressor 17 respectively.

Temperature sensors 34 and 35 may be provided to heat exchangers 16 and 17 respectively, if required.

Heat exchangers are designed on the basis of log, mean temperature differences and both units 16 and 18 are shown with countercurrent flows. To understand the principle of heat pump 10 in this application, a simple example will be considered. For simplicity, assume that the specific heats of water and milk are the same.

Milk 2 enters heat exchanger 16 at (an assumed) 37°C and leaves at 4°C, i.e. 37 -4 = 33°C of sensible heat are removed. Mains water 11 enters exchanger 18 at, say, 10°C and leaves at 55°C, i.e. gains 55 -10 = 45°C of sensible heat. Assuming that heat pump 10 is 67% efficient, this means that: 1 litre of milk from the cow will produce 33 x 2 = 0.49 litres of warm water. 3

Similarly, if water 12 is heated to 80°C, it gains 80-10 = 70°C of sensible heat, so that: llitre of milk from the cow will produce x 2 = 0.31 litres of hot water. 3

If the parameters of heat pump 10 were unable to produce water 14 at 80°C, but only, say 65°C, the 15° shortfall would be made up by mains heating 4 (not shown). By careful monitoring of the feedbacks 27, 30, 34 and 35 and control of valves 19, 28 and 31, via means 32, 27 and 30 respectively, and control 33 of compressor 171 controller 25 has a range of options to govern the outpUts 6A and 12 (13, 14 and 15) to achieve the required outputs 6A and 12 and to optimise the overall efficiency of heat pump 10.

To achieve a cold milk 6A temperature of 4°C, the working fluid temperature in pipe 22 would have to be at about -5°C and it would leave exchanger 16 in pipe 23 at, perhaps, 30°C. Compressor 17 would have to raise the working fluid temperature in pipe 20 to, say, 65°C and 90°C to produce 55°C and 80°C water respectively. The condensed working fluid would leave exchanger 18 at, say, 20°C via pipe 21 and expand through valve 19 down to about -5°C.

The above examples are given only to illustrate the principle of the invention and the skilled man will understand what is achievable in practice. Even if all these ideals cannot be fully achieved and it is necessary to provide additional chilling 3A and ? or mains 4 top up heating to 80°C (not shown), calculations show that major cost savings can be gained and, on a farm producing 14000 litres of milk per day, the pay-back period for the installation would be under two years. (This is above the average level of milk production with 3-4000 litres I day being more usual but, even at this level, significant savings are achievable.) In a practical use of the apparatus of the invention in winter, the aim would be to maximise warm water production 13 so heat pump 10 would be operated at this setting. However, for, perhaps, the last half hour of the milking operation, the selling would be changed to the hot water 14 output, so that enough freshly heated water was available for the S sterilisation of the equipment 2, 16, 6A (and 3A, 38, 3C, if required). This would optimise the system in winter. The same procedure may be adopted in summer, allowing the cows to have a good drink before they left parlour 1 and returned to the field.

In addition to direct cost savings on power 4 for chiller 3 (Fig. 1) and the provision of hot water for sterilising twice a day, other benefits provided by the apparatus of the invention are space heating for the calf nursery and warming the drinking water (especially in winter), with its attendant increase of milk production. An extra, undefinable Health & Safety benefit is the use of warm water to de-ice external access ways to the dairy, e.g. after winter snowfa Ils.

Thus, the skilled man will appreciate the comprehensive advantages of the invention to modern milk production.

S

Claims

Claims:..1. Apparatus for chilling milk on continuous basis comprising a heat pump to cool the milk and produce heated water for use elsewhere in the milk production facility.S
2. Apparatus for chilling milk, as claimed in claim 1, wherein the milk comes from any lactating animal(s).
3. Apparatus for chilling milk, as claimed in claim 2, wherein the lactating animals are cows, goats or sheep.
4. Apparatus for chilling milk, as claimed in any preceding claim, wherein the milk is passed directly from the animals being milked to the milk chilling heat pump.
5. Apparatus for chilling milk, as claimed in claim 4, wherein the heat pump removes heat from the milk at body temperature and transfers it to water, raising its temperature.
6. Apparatus for chilling milk, as claimed in claim 5, wherein the water is mains water.
7. Apparatus for chilling milk, as claimed in claims 5 or 6, wherein the water from the heat pump is warm and suitable for cows to drink and I or fpr mixing with milk for calves to drink.
8. Apparatus for chilling milk, as claimed in claims 5 or 6, wherein the water from the heat pump is hot water suitable for sterilising apparatus.
9. Apparatus for chilling milk, as claimed in claims 7 or 8, wherein the water from the heat pump is used either directly or indirectly for heating.
10. Apparatus for chilling milk, as claimed in claim 9, wherein the heating is undertloor heating.
11. Apparatus for chilling milk, as claimed in c!aim 9, wherein the heating is space heating.
12. Apparatus for chilling milk, as claimed in claims 7 or 8, wherein the warm Water and hot water is stored in different tanks.
13. Apparatus for chilling milk, as claimed in any preceding claim, wherein the heat pump has separate settings to produce either warm water or hot water, as required.
14. Apparatus for chilling milk, as claimed in claim 1, wherein the hot water is used for sterilisation of the milk production equipment.
15. Apparatus for chilling milk, as claimed in any preceding claim, wherein the warm or hot water is used to keep access areas ice-free.
16. Apparatus for chilling milk, as claimed in any preceding claim, wherein a controller is provided with means to a monitor parameter(s) of the output(s) of the heat pump against predetermined value(s) and to take remedial action when the monitored parameter(s) deviate from the preset value(s).
17. Apparatus for chilling milk, as claimed in claim 16, wherein the remedial action involves control of a valve(s) in a flow line(s).
18. Apparatus for chilling milk, as claimed in claim 16, wherein the remedial action involves control of the compressor in the heat pump.
19. Apparatus for chilling milk, as claimed in claim 16, wherein the remedial action involves providing additional chilling.
20. Apparatus for chilling milk, as claimed in claim 16, wherein the remedial action involves providing additional heating.
21. A method for chilling milk on continuous basis comprising:-i) providing a milking parlour where lactating animals are milked, the milk being at the animals' body temperature; ii) passing the milk from the parlour to a heat pump; iii) cooing the milk in the heat pump and extracting heat therefrom; iv) passing the cooled milk to a storage means for immediate, or subsequent, processing; v) using the heat extracted from the milk to produce heated water; characterised in that the heated water has a temperature higher than that of the body temperature of the animals being milked and that the heated water and I or heat in the heated water is used elsewhere in I around the milk production facility.
22. A method of cooling milk, as claimed in claim 21, wherein the milk is cooled to a temperature suitable for an extended period of storage, without there being significant deterioration of its condition.
23. A method of cooling milk, as claimed in claim 21, wherein the heat pump is used to produce both warm water for drinking and hotter water for use sterilising the milk production equipment.
24. A method of cooling milk, as claimed in claim 23, wherein the warm water is fed to lactating cattle and / or mixed with milk and fed to calves.
25. A method of cooling milk, as claimed in claim 23, wherein the hotter water is used, either directly or with additional heating, to sterilise the milk production equipment.
26. A method of cooling milk, as claimed in claim 23, wherein the heated water is used for space heating.
27. A method of cooling milk, as claimed in claim 23, wherein the heated water is used for keeping access areas frost / ice free.
28. Apparatus and method of cooling milk on a continuous basis as described in and by the above statement with reference to the accompanying drawings.