Device for the heat treatment of wort

Abstract

The invention relates to a device (1) for heat treatment of wort comprising a vessel (2) with a bottom (3) for receiving the wort, at least one heating element (4) for heating supplied wort, and at least one outlet (5) for removing wort from the vessel (2), wherein the device (1) comprises at least one bottom-side arranged inlet (6) for predominantly horizontal return of the heated wort to the vessel (2).

Description

[0001] The invention relates to a device for the heat treatment of wort.

[0002] In distilling or brewing, especially beer, a crucial process step is the heat treatment of the wort. This is primarily intended to kill microorganisms in the wort and to cause proteins to coagulate and precipitate for removal. Furthermore, it is important to remove unwanted flavor compounds, particularly dimethyl sulfide (DMS), from the wort. Steam is a particularly effective method for removing these flavor compounds. Other reasons for heat treatment are well known to experts.

[0003] A device operating on this principle is known from DE 10 2015 111 837 B3. In this process, wort is drawn from a vessel directly below its surface, heated, and returned to the vessel at the bottom. The returned wort is at a higher temperature and pressure than the wort in the vessel, causing steam bubbles to form upon its introduction. These bubbles rise in the wort and carry away the unwanted flavor compounds. The introduction is vertical. The steam bubbles are formed by flash evaporation.

[0004] A disadvantage of flash evaporation is its lower efficiency in terms of flavor removal compared to evaporation at constant atmospheric pressure. This is because, during flash evaporation, the gas phase is not in equilibrium with the pressurized liquid (wort), but rather with the depressurized liquid. As a result, fewer volatile compounds are removed relative to the evaporated wort, leading to lower relative evaporation efficiency and requiring more energy for the same result. Flash evaporation is achieved by heating the wort in a vessel to a temperature above its boiling point at ambient pressure. This process is used, for example, in wall-heated kettles.

[0005] Wall-heated kettles, however, generally have a lower efficiency than systems with heating elements for heating smaller quantities of wort and for recirculating the heated wort. Another method that uses evaporation to heat the wort is rectification, which requires a separate device with corresponding space and cost requirements.

[0006] There is therefore a great need for a device that enables the efficient, cost-effective, and space-saving removal of flavorings. Particular emphasis is placed on the ease of retrofitting existing systems.

[0007] This problem is solved in a surprisingly simple but effective way by a device for the heat treatment of wort according to the teaching of main claim 1.

[0008] According to the invention, a device for the heat treatment of wort is proposed, wherein the device comprises a vessel with a bottom for receiving the wort, at least one heating element for heating the supplied wort, and an outlet for removing wort from the vessel or the heating element. The device is characterized in that it includes an inlet arranged at the bottom for the predominantly horizontal return of the heated wort to the vessel.

[0009] Within the scope of the invention, it has been recognized that a pressure gradient exists in the liquid wort, extending from the bottom to the surface, which, as with all liquids, arises due to the liquid's own weight. Due to the relationship between boiling point and pressure, the boiling point also decreases from the bottom to the surface of the wort in the vessel. This means that wort at the bottom of the vessel boils at a higher temperature than wort at the surface. To achieve boiling of the wort, the drawn-off wort is heated to a temperature that corresponds to or is slightly lower than the boiling point at the bottom of the vessel. The horizontal introduction prevents flash evaporation, which would occur due to a rapid pressure drop caused by accelerating the wort horizontally.The pressure drop arises from the decrease in the gravitational pressure exerted on the wort layers above the incoming wort in the vessel, caused by the rising wort and the resulting reduction in the number of wort layers. Due to known physical phenomena, the heated wort rises through the cooler wort in the vessel, reaching pressure layers where its temperature is sufficient for boiling. Boiling therefore occurs as a true evaporation process under equilibrium conditions, and not based on flash evaporation. Preferably, the wort reaches such a pressure layer after rising 5 to 100 cm in the brew kettle. A further advantage of horizontal introduction is that it prevents the wort from rising too quickly within the vessel.A vertical inlet accelerates the upward movement caused by the temperature difference to such an extent that flash evaporation occurs rather than boiling, since the vertical inlet accelerates the wort in a vertical direction. Furthermore, with a horizontal inlet, an energy exchange of excess energy—that is, from the excessively high temperature of the wort, which would cause flash evaporation—to the cooler wort at the bottom of the vessel is possible. The fundamental idea of ​​the invention is therefore to achieve boiling of the wort by specifically utilizing the pressure gradient and the associated gradient of the boiling point within the wort. This is made possible by the horizontal inlet of the wort at the bottom of the vessel. It is preferably conceivable that the setting of the correct temperature is monitored by means of at least one sensor, in particular a pressure sensor arranged at the bottom of the vessel and / or a temperature sensor arranged at the inlet.The sensor is connected in particular to a control unit which can control the heating element.

[0010] The device for heat-treating wort comprises a vessel that receives the wort. For this purpose, the vessel has a bottom and at least one wall extending from the bottom, the bottom and wall enclosing a cavity into which the wort is introduced. The vessel is preferably a wort kettle, a brew kettle, a brewing kettle, a brewing vessel, a brewing kettle, and / or a still. It is irrelevant what type of wort is heat-treated in the device according to the invention; in particular, but by no means exclusively, it can be beer wort or fermented wort. Furthermore, it is conceivable that the wort contains at least partially fermented mash and / or is produced from it. The term "wort" is familiar to those skilled in the art.

[0011] The device further comprises a heating element for heating the supplied wort. The method of wort supply is irrelevant. Supply can be effected by a wort intake device, such as a pump, and / or by a line. Preferably, the heating element is an external boiler, which is supplied by a line connected to the outlet. Alternatively, the heating element can be an internal boiler, which is arranged upstream of the outlet. In this case, a device for assisting wort intake by suction is preferred, in particular a pump. The pump draws the wort past or through the internal boiler into the outlet, thus enabling the return of the heated wort according to the invention. The purpose of the heating element is to heat at least a portion of the wort that is supplied to the horizontal return flow in the vessel.

[0012] The device further comprises an outlet through which wort can be drawn from the vessel. The drawn wort can be drawn past and / or through an internal boiler or fed to an external boiler. In the simplest embodiment, the outlet is an opening in the vessel wall or bottom. It is also conceivable that the outlet comprises a tube or that a tube is arranged in front of the outlet, extending into the vessel. In this way, wort can be drawn from any point within the vessel. Preferably, the device comprises several outlets, in particular 2, 3, 4, 5, 6, 7, 8, 9, or 10 outlets, which allow for wort to be drawn from different locations.

[0013] At its base, the device comprises at least one inlet for the predominantly horizontal return of the heated wort to the vessel. In other words, the quantity of wort heated by the heating element is returned to the vessel via the inlet, with the return occurring in one or more directions, the directional component parallel to the horizontal being greater than the directional component perpendicular to the horizontal plane. The method of achieving the horizontal return is arbitrary; in particular, a corresponding arrangement of the inlet and / or a deflection device within the vessel is conceivable. More preferably, the device comprises several inlets, in particular 2, 3, 4, 5, 6, 7, 8, 9, or 10 inlets, which allow for return at various points. The inlets are also preferably arranged regularly around the circumference of the vessel.

[0014] The method of conveying the wort from the outlet to the heating element or to the inlet, or vice versa, is fundamentally arbitrary; preferably, it is conveyed by means of at least one line, in particular at least one pipe. Furthermore, it is conceivable that the device includes additional inlets and / or outlets, by means of which the supply and / or removal of wort is made possible, particularly before or after heat treatment. It is also conceivable that the device includes a lid or is closed, thereby allowing an increase in pressure and / or temperature, in particular of gas located above the wort, especially vapors. Particularly preferably, the temperature of the gas corresponds to the boiling point of the wort. This prevents flash evaporation at the surface of the wort. The boiling point of the wort at atmospheric pressure is approximately 100°C. Preferably, the temperature of the wort in the vessel and of the gas is 100°C.The boiling point of the wort at the inlet depends on the height of the wort level relative to the inlet. The higher the wort level, the higher the pressure at the inlet and therefore the boiling point. At a wort level of 3 meters relative to the inlet, the boiling point is approximately 103°C.

[0015] Advantageous further developments of the invention, which can be implemented individually or in combination, are presented in the dependent claims.

[0016] It is conceivable that the recirculation occurs at an angle of -40° to +40° to the horizontal. It has been shown that recirculation at this angle particularly effectively prevents flash evaporation during recirculation. More preferably, the recirculation occurs at an angle of -30° to +30° to the horizontal, even more preferably at an angle of -20° to +20° to the horizontal, and most preferably at an angle of -10° to +10° to the horizontal.

[0017] Furthermore, it is conceivable that the inlet comprises a bottom opening with a cover having a rim positioned above it, the rim of which is spaced away from the bottom. This design is a particularly simple way to enable horizontal recirculation, as the wort returned through the opening is deflected by the cover and flows out at the rim of the cover into the vessel. Additionally, heat exchange can be effected via the cover between the heated, recirculated wort and the wort still in the vessel. By spacing the rim of the cover from the bottom, the heated wort can be recirculated horizontally, or predominantly horizontally, into the vessel. The angle of recirculation is determined by a possible curvature of the bottom or the cover itself.It is evident to the expert that the angle of the return flow is determined immediately upon entry into the vessel, since the heated wort instantly experiences a buoyancy force in the colder wort contained in the vessel, in addition to the return angle.

[0018] In a further development, it is conceivable that the cover has a raised section in the center, with a shield-like structure arranged around this raised section, curving towards the bottom. The raised section is oriented towards the top of the vessel containing the wort, while the curvature is formed towards the bottom. A bottom-side opening located centrally beneath the cover is particularly preferred. This design serves to keep the flow area for the wort constant and / or to reduce it towards the outside, with the curvature being determined taking into account the shape of the bottom. This also helps to maintain a constant wort pressure.

[0019] Furthermore, it is conceivable that at least one flow area, spanning circumferentially between the cover, particularly the rim, and the bottom, is essentially equal to and / or smaller than the area of ​​the bottom opening. This results only in a deflection of the wort and not in any acceleration or deceleration as it flows into the vessel. This makes the inflow of heated wort particularly easy and effective to control. The calculation of the flow area and the bottom opening depends on the geometry. If the bottom opening is a circle, the area is calculated by multiplying π by the square of the radius.If the opening is an annular opening, as described elsewhere, the area is calculated as π multiplied by the difference between the square of the outer radius and the inner radius of the annular opening. The flow area A(r) for a circular cover and an inlet positioned centrally beneath the cover is calculated using the formula A(r) = 2πrh. r , where r is the distance to the inlet (radius) and h r The distance between the floor and the cover (height) is [value missing]. Preferably, the cross-sectional area of ​​a pipe connected to the inlet is equal to the area of ​​the opening on the floor. Calculation methods for other geometries are well known.

[0020] The term "essentially" means that there is only a minor, and in particular non-significant, change, modification, and / or deviation from the relevant conditions, namely the equality of the areas. Specifically, a deviation of a maximum of 30% from the smaller of the two areas is covered by the term "essentially".

[0021] Furthermore, it is conceivable that the radius of the cover is at least 10% of the radius of the vessel. More preferably, the radius of the cover is at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the radius of the vessel. This allows for a uniform and efficient introduction of the heated wort, preferably with premature heat exchange via the cover. The heated wort thus causes the wort in the vessel above the cover to boil, as it is under lower pressure, and effectively prevents flash evaporation, since the heated wort has already cooled somewhat.

[0022] It is also conceivable that the cover is rotationally symmetrical, in particular a body of revolution. The opening at the bottom is preferably located centrally beneath the cover. This results in identical or nearly identical conditions for the heated wort upon entry into the vessel. In other words, it is irrelevant at which point in the cover the heated wort enters the vessel. This prevents turbulence that could promote flash evaporation. The wort then rises continuously through the wort in the vessel, primarily due to buoyancy, thus promoting boiling.

[0023] The term "rotationally symmetric" refers to a geometry that transforms into itself when rotated by an angle other than 360°.

[0024] The term "solid of revolution" refers to a geometry that is created by rotating a curve 360° around an axis.

[0025] Furthermore, it is conceivable that the cover includes at least one recess in the area of ​​the rim. As the heated wort flows into the vessel below the cover, some of the less hot wort from the vessel is drawn through the recess under the cover. This results in an exchange of heat beneath the cover, which promotes the boiling of the wort and largely prevents flash evaporation. The cover preferably comprises two to 20 recesses distributed regularly or irregularly around the rim.

[0026] The term "in the area of ​​the edge" refers to an area that is directly adjacent to the edge. In particular, the term "in the area of ​​the edge" refers to the outer 20% of the cover that is directly adjacent to the edge.

[0027] In a further development, it is conceivable that the outlet is arranged centrally in the vessel. This results in a particularly low-turbulence and uniform distribution of heat from the heated wort. Even more preferably, the wort is returned horizontally from the centrally arranged outlet in a 360° radius. This can be achieved in particular by a cover as described elsewhere, wherein the edge of the cover rises from the base at every point, except for a small number of supports if necessary, and wherein the distance from the base to the edge is the same at every point. Particularly preferably, the central extraction is achieved by a pipe extending towards the center of the vessel. The cover can be attached to the pipe. The inlet is an annular opening arranged around the pipe.This design results in a particularly even heat distribution due to the very favorable flow behavior of the wort in the vessel.

[0028] In an alternative embodiment of the invention, it is conceivable that the outlet is arranged in the lower third, particularly directly at the bottom, of the vessel. This allows the relationships between the pressure of the wort in the vessel and the boiling caused by the recirculated wort, described in detail elsewhere, to be utilized particularly efficiently.

[0029] In one embodiment of the invention, the heating element is an external boiler, wherein an outlet line is arranged between the outlet and the heating element, and an inlet line is arranged between the inlet and the heating element. A first bypass line, running parallel to the heating element, is arranged between the inlet line and the outlet line. Within the scope of the invention, it has been recognized that an external boiler is a very efficient way to heat the wort, and the external boiler operates particularly efficiently when heating occurs at a high flow rate. At lower flow rates, so-called fouling occurs, which refers to deposits on the heating elements that reduce the efficiency of the heating elements and necessitate time-consuming and expensive cleaning.Furthermore, heating to temperatures above 100°C is preferred, as the conversion of dimethylsulfonium propionate (DMSP) to DMS is accelerated at these temperatures, ultimately increasing ejection efficiency. The arrangement of the first bypass allows at least a portion of the wort to be passed through the external boiler multiple times, thus maintaining a high temperature in the external boiler despite a high flow rate. Particularly when the wort in the vessel has a lower temperature, especially below 80°C, it is process-wise more efficient to introduce the heated wort at only a few degrees above the vessel temperature. To enable this while still operating the external boiler efficiently, a portion of the heated wort can be recirculated via the bypass line by feeding it back to the heating element through the first bypass line.This allows the external boiler to be operated optimally while simultaneously heating the wort in the vessel only slowly. Ideally, the wort in the vessel should be at a temperature of 100°C, and the heated and recirculated wort should have a temperature corresponding to the boiling point of the wort at the bottom of the vessel. In particular, it is conceivable that the heated and recirculated wort has a temperature between 90°C and 110°C.

[0030] In a further development of the invention, it is conceivable that a lockable non-return valve with a flow direction from the inlet line to the outlet line is arranged in the first bypass line. This allows the flow through the bypass line to be easily regulated and prevents backflow of the heated wort to the outlet line. The wort can therefore be passed through the external boiler multiple times. Alternatively, it is conceivable that a lockable non-return valve with a flow direction from the outlet line to the inlet line is arranged in the first bypass line. This allows cooler wort from the vessel to be mixed with the heated wort to reduce or regulate the temperature of the wort during recirculation. Particularly preferred is the non-return valve being controllable by means of a control unit described elsewhere, which receives data from at least one sensor.

[0031] Furthermore, it is conceivable that a second bypass line is arranged between the inlet and outlet lines, with the second bypass line being located upstream of the first bypass line in the outlet line, particularly immediately after the outlet, and downstream of the first bypass line in the inlet line, particularly immediately before the inlet. This makes it possible to mix colder wort directly from the vessel with the heated wort before recirculation. This generally allows the temperature in the external boiler to be increased while still allowing the wort to be recirculated at a lower temperature. Simultaneously, it is possible to return the wort to the vessel at a lower temperature, thus decoupling the temperature in the external boiler from the temperature in the vessel.It is possible to achieve slow heating at a high temperature in the outdoor cooker, in order to utilize both effects as efficiently as possible.

[0032] In a further development, it is conceivable that a lockable check valve with a flow direction from the outlet line to the inlet line is arranged in the second bypass line. This allows the flow rate to be regulated and backflow and its associated disadvantages to be prevented. Particularly preferred is the check valve being controllable by means of a control unit described elsewhere, which receives data from at least one sensor.

[0033] Furthermore, it is conceivable that the vessel includes a tap. Preferably, the tap is connected to the inlet line downstream of the first bypass line. The tap can be used, like the second bypass line, to mix colder wort into the inlet stream. Even more preferably, a lockable non-return valve and / or a pump can be arranged in or on the tap.

[0034] Further details, features, and advantages of the invention will become apparent from the following description of the preferred embodiments in conjunction with the dependent claims. The respective features can be implemented individually or in combination with one another. The invention is not limited to the embodiments shown. The embodiments are illustrated schematically in the figures. Identical reference numerals in the individual figures denote identical or functionally equivalent elements, or elements that correspond to one another with respect to their function.

[0035] Specifically, we show: Fig. 1: a schematic representation of a first embodiment of a device according to the invention; Fig. 2: a schematically represented section of a second embodiment of a device according to the invention; Fig. 3: a schematically represented section of a third embodiment of a device according to the invention; Fig. 4: a schematic representation of a fourth embodiment of a device according to the invention; Fig. 5: a schematic representation of a fifth embodiment of a device according to the invention; Fig. 6: a schematic representation of a sixth embodiment of a device according to the invention; and Fig. 7: a schematic representation of a seventh embodiment of a device according to the invention.

[0036] Fig. Figure 1 shows a schematic representation of a first embodiment of a device 1 according to the invention. The device 1 comprises a vessel 2, which is a brewing kettle. The vessel 2 can hold wort. The vessel 2 has a lid that can be opened. The first embodiment includes a heating element 4 designed as an external boiler. An outlet 5 for drawing wort from the vessel 2 is arranged centrally on a base 3 of the vessel 3. A pipe is connected to the outlet 5, extending to the center of the vessel 2, so that the wort is drawn from the center of the vessel 2. The drawn wort is directed to the heating element 4 for heating. An inlet 6 for returning the wort heated by the heating element 4 to the vessel 2 is arranged around the pipe. The inlet 6 is designed as an annular opening with a cover 7 arranged over it, whereby the wort is deflected horizontally during the return flow. The cover 7 is held by the pipe.The flow direction of the wort in device 1 is shown by arrows. Horizontal recirculation prevents flash evaporation. The recirculated wort is hotter than the wort in vessel 2 and therefore rises. As it rises, the pressure decreases, and the recirculated wort boils when the decreasing liquid pressure allows it.

[0037] Fig. Figure 2 shows a schematically represented section of a second embodiment of a device 1 according to the invention. The second embodiment essentially corresponds to the first embodiment (see Figure 2). Fig. 1) wherein the cover 7 is designed differently and the pipe connected to the outlet 5 is shorter. The cover 7 includes a rim 8 which, together with the base 3, encloses an area through which the wort flows back into the vessel 2. This area is the same size as the cross-sectional area of ​​the annular opening. This ensures that the wort is returned to the vessel 2 with minimal turbulence. The cover 7 further includes a screen 10 with a raised section 9 or a bulge, which is intended to keep the flow area constant, at least towards the rim 8. This helps to keep the flow velocity and / or pressure in the heated wort as constant as possible.

[0038] Fig. Figure 3 shows a schematically represented section of a third embodiment of a device 1 according to the invention. The third embodiment essentially corresponds to the first and second embodiments (see Figure 3). Fig. 1 and Fig. 2), wherein the cover 7 has recesses 11 in the area of ​​the rim 8. Since the heated wort flows under the cover and since flowing liquids have a lower static pressure than stagnant liquids, some of the wort from the vessel 2 is drawn through the recesses 11 under the cover 7 and mixes there with the recirculated wort. This promotes temperature equalization with the advantages described elsewhere. The direction of wort flow in the device 1 is shown by arrows.

[0039] Fig. Figure 4 shows a schematic representation of a fourth embodiment of a device 1 according to the invention. The fourth embodiment essentially corresponds to the first, second and third embodiments (see Figure 4). Fig. 1, Fig. 2 and Fig. 3), wherein the third embodiment comprises a heating element 4 designed as an internal boiler. The heating element 4 is arranged upstream of the outlet 5. To effect the circulation of the wort from the outlet 5 to the inlet 6, the device 1 includes a pump 12. The direction of flow of the wort in the device 1 is shown by arrows.

[0040] Fig. Figure 5 shows a schematic representation of a fifth embodiment of a device 1 according to the invention. The fifth embodiment is essentially the same as the first embodiment (see Figure 5). Fig. 1) wherein an outlet line 13 connects the outlet 5 to the heating element 4 and an inlet line 14 connects the heating element 4 to the inlet 6. The outlet line 13 is connected to the inlet line 14 via a first bypass line 15. The flow direction and flow rate can be determined by means of a controllable non-return valve (not shown). The first bypass line 15 allows a portion of the wort taken from the vessel 2 and heated to be returned to the heating element 4. This allows the heating element 4 to be operated at a higher temperature, thereby increasing efficiency. The flow direction of the wort in the device 1 is indicated by arrows.

[0041] Fig. Figure 6 shows a schematic representation of a sixth embodiment of a device 1 according to the invention. The sixth embodiment essentially corresponds to the fifth embodiment (see Figure 6). Fig. 5), wherein, in addition to the first bypass line 15, a second bypass line 16 is arranged between the inlet line 14 and the outlet line 13. The second bypass line 16 is arranged upstream of the first bypass line 15 in the inlet line 14 and downstream of the first bypass line 15 in the outlet line 13. The second bypass line 16 preferably allows, by means of a controllable reflux valve (not shown), the targeted addition of cooler wort from the vessel 2 to the wort heated by the heating element 4. This allows the wort in the vessel to be heated slowly, and the recirculated wort to be only a few degrees warmer than the wort in the vessel 2, while the heating element 4 can still be operated at a high temperature, which overall increases the efficiency of the device 1.The device 1 preferably comprises at least one temperature sensor, wherein the controllable backflow valve in the first bypass line and / or in the second bypass line is controlled taking into account the temperature measured by the temperature sensor. Temperature sensors are preferably arranged in the vessel 2, in the outlet line 13 and / or in the inlet line 14. The flow direction of the wort in the device 1 is shown by arrows.

[0042] Fig. Figure 7 shows a schematic representation of a seventh embodiment of a device 1 according to the invention. The seventh embodiment essentially corresponds to the sixth embodiment (see Figure 7). Fig. 6), the function of the second bypass line being taken over by a connection 17. The connection 17 connects the vessel 2 at its bottom to the inlet line 14. The direction of flow of the wort in the device 1 is shown by arrows.

Claims

[1] Device (1) for heat treatment of wort comprising a vessel (2) with a bottom (3) for receiving the wort, at least one heating element (4) for heating supplied wort, and at least one outlet (5) for taking wort from the vessel (2), characterized by , that the device (1) comprises at least one bottom-mounted inlet (6) for the predominantly horizontal return of the heated wort to the vessel (2). [2] Device (1) according to claim 1 characterized by , that the return is carried out at an angle of -40° to +40° to the horizontal. [3] Device (1) according to claim 1 or 2, characterized by , that the inlet (6) comprises a bottom opening with a cover (7) arranged above it having a rim (8), wherein the rim (8) of the cover (7) is spaced away from the bottom (3). [4] Device (1) according to claim 3, characterized by, that the cover (7) has a central elevation (9), wherein a screen (10) with a curvature towards the ground (3) is arranged around the elevation (9). [5] Device (1) according to claim 3 or 4, characterized by , that at least one flow area, which is spanned in the circumferential direction between the cover (7), in particular the edge (8), and the bottom (3), is substantially equal to the area of ​​the bottom-side opening and / or smaller than the area of ​​the bottom-side opening. [6] Device (1) according to any one of claims 3 to 5, characterized by , that the radius of the cover (7) is at least 10% of the radius of the ground (3). [7] Device (1) according to any one of claims 3 to 6, characterized by , that the cover (7) is rotationally symmetric, in particular a body of revolution. [8] Device (1) according to any one of claims 3 to 6, characterized by, that the cover (7) in the area of ​​the edge (8) includes at least one recess (11). [9] Device (1) according to any of the preceding claims, characterized by , that the outlet (5) is located in the center of the vessel. [10] Device (1) according to any one of claims 1 to 8, characterized by , that the outlet (5) is located in the lower third of the vessel. [11] Device (1) according to any of the preceding claims, characterized by , that the heating element (4) is an external cooker, that an outlet line (13) is arranged between the outlet (5) and the heating element (4) and an inlet line (14) is arranged between the inlet (6) and the heating element (4) and that a first bypass line (15) running parallel to the heating element (4) is arranged between the inlet line (14) and the outlet line (13). [12] Device (1) according to claim 11, characterized by, that in the first bypass line (15) a lockable backflow valve is arranged with a flow direction from the inlet line (14) to the outlet line (13) or with a flow direction from the outlet line (13) to the inlet line (14). [13] Device (1) according to claim 11 or 12, characterized by , that a second bypass line (16) is arranged between the inlet line (14) and the outlet line (13), wherein the second bypass line (16) is arranged upstream to the first bypass line (15) in the outlet line (13), in particular immediately after the outlet (5), and downstream to the first bypass line (15) in the inlet line (14), in particular immediately before the inlet (6). [14] Device (1) according to claim 13, characterized by , that in the second bypass line (16) a lockable backflow valve with a flow direction from the outlet line (13) to the inlet line (14) is arranged. [15] Device (1) according to any of the preceding claims, characterized by , that the vessel (2) includes a puncture (17).

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