Device for heating liquid food

Abstract

A device for heating liquid foodstuffs, in particular milk, comprises a pumping device for conveying the liquid foodstuff from a storage container to an outlet, and a heating device arranged between the pumping device and the outlet. The heating device is designed as a steam-heated heat exchanger having two fluidically separated flow paths in mutual thermal contact, wherein a first flow path is connectable or connected to a steam generator on the inlet side, and a second flow path is connectable or connected to the pumping device on the inlet side and to the outlet on the outlet side.

Description

[0001] The present invention relates to a device for heating liquid foodstuffs, in particular milk, comprising a pumping device for conveying the liquid foodstuff from a storage container to an outlet and comprising a heating device arranged between the pumping device and the outlet.

[0002] In hot drink machines such as fully automatic coffee machines, beverage components such as milk or other liquid foods are held in storage containers and heated and, if necessary, frothed when dispensed. Two different technologies have been established for heating the beverage: either the medium can flow through a heat exchanger or instantaneous water heater such as a thermoblock and is heated in the process, or hot steam can be mixed with the medium when dispensed (steam injection). A combination of the above-mentioned processes is also known. EP 2 583 596 B1, for example, describes a two-stage heating process for milk. In a first heating stage, the milk is heated in the instantaneous water heater. Subsequently, steam is added for additional heating in a second heating stage.

[0003] A flow-through heater requires a relatively large surface area for heat exchange to transfer the required energy. This results in a large volume of milk that must be rinsed and cleaned. The milk in the line is discarded during each cleaning or rinsing process.

[0004] When heating milk or other protein-containing foods, deposits can form on the inner wall of the instantaneous water heater. The rate of deposits depends largely on the temperature and the length of time the instantaneous water heater is in contact with the milk or other foods. This means that the temperature must be limited to approximately 65°C. While this time can be reduced by regular rinsing, this leads to significant milk and energy loss. As a result, maximum milk temperatures of approximately 55°C are possible with a conventional thermoblock.

[0005] Due to its design, a thermoblock has a high thermal mass. This means that cold milk cannot be dispensed through the thermoblock, even if it is not heated. If cold milk is to be dispensed in addition to warm milk, an additional switching valve is required.

[0006] The advantage of a continuous flow heater is that the indirect heating does not destroy cold, fine-pored milk foam and largely retains its properties.

[0007] With direct steam addition, the condensation energy of steam is used to heat the milk. Heating with steam can be achieved very quickly and in a small installation space.

[0008] However, adding steam is not suitable for heating milk foam, as adding steam will destroy cold-produced milk foam, or at least impair its appearance. Furthermore, adding steam can cause noise and impair the quality of the dispensing process due to steam hammer.

[0009] An object of the invention is to provide an improved device for heating liquid foods.

[0010] The problem is solved by the features of claim 1. Advantageous embodiments can be found in the dependent claims.

[0011] In a device of the type mentioned at the outset, the invention provides that the heating device is designed as a steam-heated heat exchanger which has two fluidically separated flow paths which are in mutual thermal contact, wherein a first flow path is connectable or connected to a steam generator on the inlet side and a second flow path is connectable or connected to the pumping device on the inlet side and to the outlet on the outlet side.

[0012] By regulating the steam supply, the heating output can be easily controlled. At the same time, the high condensation energy of steam allows for a higher energy density than electric heaters, allowing the heat exchanger to be designed very compactly. A steam-heated heat exchanger can be designed with a comparatively low thermal mass.

[0013] Due to the low thermal mass and the controllable steam supply, the steam-heated heat exchanger can be brought to a non-deposit-critical temperature at the end of a product dispensing cycle, for example, by shutting off the steam supply early. This allows for a higher product temperature to be achieved. At the same time, cold products can also be dispensed without the need for an additional switching valve.

[0014] The connection between the first flow path and the steam generator can be made directly or by switching via a valve device. Likewise, the connection between the second flow path and the outlet can be made directly or by switching.

[0015] Preferably, the first flow path can be connected to a steam control device, in particular a metering valve, on the inlet or outlet side. This allows for simple control or regulation of the steam supply and thus the heating output.

[0016] The device according to the invention can preferably be equipped with a selectively operable frothing device. Such a device can be implemented, for example, by an air supply upstream of the pumping device and a flow resistance such as a baffle or a static mixer downstream of the pumping device. The liquid food is frothed by the air supply arranged on the suction side of the pumping device and the increase in pressure in the pumping device due to the flow resistance. The frothing device can be deactivated by closing the air supply. The foam consistency can be influenced by controlling the air supply and / or the power of the pumping device. The frothing process is particularly successful when a gear pump is used as the pumping device.

[0017] In a preferred embodiment of the invention, the first flow path is connectable or connected on the outlet side to a food line leading from the second flow path to the outlet, preferably via a three-way connector. This allows residual steam downstream of the primary circuit of the heat exchanger to be mixed with the heated food, thus achieving reheating. The heat exchanger can be designed to be compact and require only a lower heating output. With a lower steam supply, the steam condenses in the heat exchanger, and the heat is transferred to the liquid food. If, however, the heating output is increased by increasing the steam supply, the uncondensed residual steam is automatically injected, thus resulting in reheating.

[0018] For example, solid foam requires little heating power, allowing all the steam to condense in the heat exchanger. The fact that the condensed steam (water) is subsequently added to the foam does not affect the foam consistency. This does not destroy the solid foam, unlike the addition of steam. Liquid foam or unfoamed milk, on the other hand, requires more heating power. The heat exchanger may be designed in such a way that it would not provide sufficient power on its own. Therefore, the uncondensed steam is subsequently added to the milk or liquid milk foam, thus providing reheating.

[0019] Instead of adding the condensed steam (water) to the foamed food, the connection between the outlet side of the first flow path and the food line leading to the outlet can be established via a valve arrangement. This can alternatively connect the first flow path to a drain, allowing the condensed water to be drained away when heating solid milk foam instead of mixing it into the milk foam.

[0020] The second flow path can also be connected either to the outlet or a drain via a (further) valve arrangement. This allows the heat exchanger's second flow path to be connected to the drain for rinsing, preventing residual milk and / or rinsing liquid from being discharged to the outlet and accidentally ending up in a user's drinking vessel. The heat exchanger's second flow path can also be connected to the drain for automatic cleaning cycles using a special cleaning agent.

[0021] In a particularly preferred embodiment, the device can be equipped with a steam control device arranged on the inlet or outlet side of the first flow path and with a selectively operable frothing device and with a control device which is programmed to control the frothing device and / or the pumping device to produce a solid food foam in a first operating mode and to control the steam control device to deliver a first, lower amount of steam and to control the frothing device and / or the pumping device to produce a liquid food foam in a second operating mode or to deactivate the frothing device to deliver unfoamed food and to control the steam control device to deliver a second, higher amount of steam.

[0022] In this case, it can be expediently provided that the first, lower steam quantity is set so that the steam condenses completely within the heat exchanger and the second, higher steam quantity is set so that steam still escapes on the outlet side of the first flow path, which is fed via a three-way connector to a food line leading from the second flow path to the outlet.

[0023] The two flow paths of the heat exchanger can be designed coaxially, with the first flow path preferably surrounding the second flow path. This results in a particularly compact and energy-efficient design.

[0024] The two flow paths of the heat exchanger can be connected in countercurrent. This achieves particularly effective heat transfer from the steam to the liquid food.

[0025] The device can be equipped with a temperature sensor communicating with the second flow path on the outlet side for measuring the temperature of the heated liquid food. This allows for measurement of the product temperature and, if necessary, control of the steam supply and / or the power of the pumping device to achieve a predetermined outlet temperature.

[0026] The first flow path can be connected to a cold water supply line via a valve on the inlet side. This allows the heat exchanger to be rinsed with cold water and cooled down for dispensing a cold food product.

[0027] Further advantages and features of the invention will become apparent from the following description of exemplary embodiments with reference to the figures. It shows: Fig. 1 is a water flow diagram of a device according to the invention with a steam-heated heat exchanger for heating milk in a first embodiment; Fig. 2 a second embodiment with an electric instantaneous water heater connected upstream of the steam-heated heat exchanger; Fig. 3 a third embodiment with a control valve arranged on the output side of the primary circuit of the heat exchanger; Fig. 4 shows a fourth embodiment with a valve arrangement arranged on the outlet side of the primary circuit of the heat exchanger, with which condensed steam can be directed into a drain; and Fig. 5 a fifth embodiment in which the primary circuit of the heat exchanger can be connected to a cold water supply line on the inlet side via a valve.

[0028] A first embodiment of a device for heating milk is shown in Fig. 1 is shown schematically. The milk is stored in a storage container 11. Via a suction line 12, it can be conveyed by a milk pump 13 towards a beverage outlet 27. The pressure side of the milk pump 13 is guided over a static mixer 14 (helical mixer), which acts as a flow resistance and thereby contributes to an increase in pressure in the milk pump 13. An air supply line 15 with a check valve, which prevents milk from escaping, and an air valve 17 for controlling the air supply opens into the suction line 12. The air valve can be an intermittently operated switching valve or a throttle valve such as a needle valve. The storage container 11 is housed together with the milk pump 13 in a refrigerator 18 so that the milk in the storage container 11 and the subsequent conveying line remains cool.

[0029] The milk pumped by the milk pump 13 flows via a delivery line 19 into a heating device 20, which is designed as a steam-heated heat exchanger. This is coaxially constructed with an inner flow path 21 through which milk flows and an outer flow path 22, which is connected on the inlet side via a control valve 23 to a steam generator 24 (shown only schematically here), e.g., a steam boiler, through which steam flows.

[0030] The outlet of the milk-flowing inner flow path 21 is connected to the beverage outlet 27 via a milk line 24 and an optional 3 / 2-way valve, which serves as a switching valve. Warmed milk or milk foam is dispensed in portions into a drinking vessel located below the beverage outlet. The switching valve 26 connects the milk line 25 to a drain 28 or a drainage vessel for emptying, rinsing, or cleaning.

[0031] The outlet of the steam-flowing outer flow path 22 is connected to the milk line 25 via a line 29 and a check valve 30 via a three-way connector 31. The three-way connector 31 can be designed as a T-piece with or without an integrated mixing chamber. Any remaining steam that has not yet condensed is fed into the milk line via line 29 after passing through the outer flow path of the heat exchanger 20, where it automatically reheats the milk that has been (pre-)heated in the heat exchanger.

[0032] The check valve prevents milk from being sucked into the steam line 29 during cooling of the heat exchanger and condensation of any residual steam remaining in the outer flow path 22.

[0033] A temperature sensor 32 connected to the milk line 25 serves to measure the milk temperature upstream of the outlet 27, thus enabling active control of the milk temperature. The milk temperature can be adjusted by dosing the steam quantity via the control valve 23, by controlling the milk quantity by adjusting the power of the milk pump 13, or by a combination of the aforementioned measures.

[0034] By supplying air to the intake line 12 on the intake side of the milk pump 13 via the air supply line 15, milk foam is generated in the milk pump 13 and via the static mixer 14. The consistency of the milk foam can be adjusted by adjusting the air volume.

[0035] If thicker milk foam is to be produced, more air is supplied by opening the air valve for a longer time (e.g., adjusting the duty cycle for a pulsed control) or wider (in the case of a throttle valve). In this case, the milk foam should not be destroyed by adding steam downstream of the heat exchanger. The steam quantity is therefore adjusted via the control valve 23 so that the steam condenses completely in the heat exchanger 20. Due to the higher air content, thicker milk foam has a significantly lower heat capacity, so even the reduced steam quantity is sufficient for heating.

[0036] If, on the other hand, liquid milk foam is to be produced, the air supply is throttled so that less air is supplied. Since milk foam has a rather liquid consistency anyway, adding steam downstream of the heat exchanger does not significantly affect the consistency of the milk foam. The amount of steam is therefore adjusted via the control valve 23 so that more steam flows through the heat exchanger 20, so that at most a portion of the steam condenses. The remaining steam is injected into the heated milk foam downstream of the heat exchanger 20 via the three-way connector 31, providing additional reheating with steam. Liquid milk foam can therefore be dispensed at a higher temperature than is the case when using an electric instantaneous water heater.

[0037] To dispense unfoamed milk, the air supply is closed, and the steam quantity is also increased compared to solid milk foam. Since unfoamed milk has a greater heat capacity than liquid milk foam due to the air content, the steam quantity for heating unfoamed milk can be larger than for liquid milk foam. This allows a larger amount of steam, or steam at a higher final temperature, to be injected into the heated milk, thus resulting in greater reheating. This allows milk to be heated to a significantly higher temperature during dispensing than would be possible with an electric instantaneous water heater.

[0038] In Fig. Figure 2 shows a second embodiment in which, based on the first embodiment, a conventional electric flow heater 40, in the form of a thermoblock, is additionally arranged between the milk pump 13 and the heat exchanger 20. The three-stage heating (electric flow heater, heat exchanger with steam, and subsequent steam injection) allows the initial temperature to be further increased and / or the amount of steam to be reduced, so that less water is added to the milk.

[0039] Since the flow heater 40 has a higher thermal mass than the heat exchanger 20, it cannot cool down quickly after a product has been dispensed. Therefore, if cold milk or cold milk foam is to be dispensed, a valve arrangement with two parallel shutoff valves 41, 42 is provided, with which the optionally foamed or unfoamed milk can be directed from the milk pump either through the flow heater 40 or via a bypass line 43, bypassing the flow heater 43, directly to the heat exchanger 20. Instead of two individual shutoff valves, a 3 / 2-way valve can also be used to switch the flow path between the flow heater 40 and the bypass line 43.

[0040] In Fig. 3 shows a variant as a third embodiment in which, starting from the first embodiment, the control valve 23 for adjusting the amount of steam that is passed through the outer flow path 22 of the heat exchanger 20 is now arranged on the outlet side of the outer flow path 22 in the line 29 between the heat exchanger 20 and the three-way connector 31 instead of between the steam generator 24 and the outer flow path 22 of the heat exchanger 20.

[0041] In Fig. 4 shows a fourth embodiment in which, starting from the first embodiment, the outer, steam-flown flow path 22 can be connected via a switching valve 44 either to the three-way connector 31 or alternatively to an outlet 45. Thus, it is possible to choose whether the residual steam is injected into the heated milk for reheating or discarded via the outlet 45. The latter is particularly useful when the amount of steam has been reduced to such an extent that the steam is completely or at least largely condensed in the heat exchanger 20 and / or when solid milk foam is to be produced that is not to be impaired by the introduction of steam and / or when the water condensed in the flow heater is not to be fed into the beverage.

[0042] In the event that only condensate water, i.e. the condensed steam, is to be discharged into the drain 45, a condensate separator can be used in addition to or instead of the changeover valve 44.

[0043] In Fig. Finally, Figure 5 shows a fifth embodiment, a variant based on the first embodiment, in which the outer flow path 22 of the heat exchanger 20 can be connected on the inlet side via a 3 / 2-way valve 46 either to the steam generator or to a cold water supply line 47. Thus, after a product has been dispensed, the heat exchanger can be flushed with cold water and thus cooled. This can be useful as a supplementary measure if cold, i.e., unheated, milk or milk foam is to be dispensed subsequently.

[0044] Of course, it is possible and included within the scope of the present invention to Fig.2 to 5 modifications and additions shown can be combined in any way. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 583 596 B1

[0002]

Claims

[1] Device for heating liquid foodstuffs, in particular milk, with a pumping device (13) for conveying the liquid foodstuff from a storage container (11) to an outlet (27) and with a heating device (20) arranged between the pumping device (13) and the outlet (27), characterized by in that the heating device (20) is designed as a steam-heated heat exchanger which has two fluidically separated flow paths (21, 22) which are in mutual thermal contact, wherein a first flow path (22) is connectable or connected on the inlet side to a steam generator (24) and a second flow path (21) is connectable or connected on the inlet side to the pump device (13) and on the outlet side to the outlet (27). [2] Device according to claim 1, wherein the first flow path (22) is connected on the inlet or outlet side to a steam control device (23), in particular a metering valve. [3] Device according to claim 1 or 2 with a selectively operable foaming device (14, 15, 17). [4] Device according to one of the preceding claims, in which the first flow path (22) is connectable or connected on the outlet side to a food line (259) leading from the second flow path (21) to the outlet, preferably via a three-way connector (31). [5] Device according to one of the preceding claims, in which the second flow path (21) can be connected selectively to the outlet (27) or a drain (28) via a first valve arrangement (26). [6] Device according to claim 4, wherein the connection between the outlet side of the first flow path (22) and the food line (25) leading to the outlet (27) is made via a second valve arrangement (45), via which the first flow path (22) can alternatively be connected to a drain (45). [7] Device according to claim 1, with a steam control device (23) arranged on the inlet or outlet side of the first flow path (22) and a selectively operable frothing device (14, 15, 17) and with a control device which is programmed to control the frothing device (14, 15, 17) and / or the pumping device (13) in a first operating mode to produce a solid food foam and to control the steam control device (23) to deliver a first, lower amount of steam and, in a second operating mode, to control the frothing device (14, 15, 17) and / or the pumping device (13) to produce a liquid food foam or to deactivate the frothing device (14, 15, 17) to deliver unfoamed food and to control the steam control device (23) to deliver a second, higher amount of steam. [8] Device according to claim 7, in which the first, lower steam quantity is set so that the steam condenses completely within the heat exchanger (20) and the second, higher steam quantity is set so that steam still emerges on the outlet side at the first flow path (22), which steam is fed via a three-way connector (31) to a food line (25) leading from the second flow path (21) to the outlet (27). [9] Device according to one of the preceding claims, in which the flow paths (21, 22) are coaxial, wherein preferably the first flow path (22) surrounds the second flow path (21). [10] Device according to one of the preceding claims, in which the flow paths (21, 22) are connected in countercurrent. [11] Device according to one of the preceding claims with a temperature sensor (32) communicating with the second flow path (21) on the output side for measuring the temperature of the heated liquid food. [12] Device according to one of the preceding claims, in which the first flow path (22) is connectable on the inlet side via a valve (46) to a cold water supply line (47).

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