WO2015018641A2

WO2015018641A2 - Steam generator for generating water vapor and system for food preparation comprising such a steam generator

Info

Publication number: WO2015018641A2
Application number: PCT/EP2014/065829
Authority: WO
Inventors: Herbert Mederer
Original assignee: Pasta E Sughi Sa
Priority date: 2013-08-06
Filing date: 2014-07-23
Publication date: 2015-02-12
Also published as: DE102013215399B3; WO2015018641A3

Abstract

The invention relates to a steam generator (3) for generating water vapor, comprising a pressure vessel (11) having a longitudinal pressure vessel axis (13), a floor (14), a side wall (15) connected to the floor (14), a cover (17), which is removably connectable to the side wall (15), and an interior chamber (20) enclosed by the floor (14), the side wall (15) and the cover (17), a heating element (21) arranged in the interior chamber (20), a water supply line (22), led out of the interior chamber (20) in a sealed manner, for supplying water to the pressure vessel (11), wherein the water supply line (22) has a water supply opening (24) which protrudes into the interior chamber (20), at least one steam withdrawal valve, led out from the interior chamber (20) in a sealed manner, for withdrawing steam from the pressure vessel (11), wherein the at least one steam withdrawal valve (27, 29) has a steam withdrawal opening (28, 20) which protrudes into the interior chamber (20), wherein the water supply line (22) and the at least one steam withdrawal valve are each led out of the interior chamber (20) through the cover (17).

Description

Steam generator for generating water vapor and plant for food preparation comprising such a steam generator

The content of German Patent Application 10 2013 215 399.6 is incorporated herein by reference.

The invention relates to a steam generator for generating steam and a plant for food preparation comprising such a steam generator.

Steam generators have long been known for example from DE 27 42 876 AI. Such steam generators are used for heating a fluid, in particular water, for transferring from the liquid to the gaseous vapor phase. The known from the prior art steam generators are complicated and limited in their application.

It is an object of the present invention to improve a steam generator for generating water vapor such that the structure of the steam generator is simplified.

This object is achieved by a steam generator having the features specified in claim 1. The essence of the invention is that all lines for supplying and discharging fluids in and out of the steam generator are led out through a lid of a pressure vessel. The pressure vessel has a pressure vessel longitudinal axis, a bottom and a side wall connected to the bottom. In particular, the floor is welded to the side wall. The floor may, for example, be arched and is essentially in particular lowered. oriented right to the pressure vessel longitudinal axis. The side wall is designed substantially tubular with a circular contour perpendicular to the pressure vessel longitudinal axis. The lid is detachably connectable to the side wall, for example by screwing. The cover is sealingly connected to the side wall and oriented in particular perpendicular to the pressure vessel longitudinal axis. From the bottom, the side wall and the lid, an interior of the pressure vessel is surrounded. In the interior, a heating element is arranged to heat the supplied fluid, in particular water. The feeding of water into the interior takes place by means of a water supply line. The water supply line is guided from the outside into the interior of the pressure vessel. The Wasserzuführ- line has a water supply opening, which projects into the interior. The water supply line is also sealed out of the interior. In particular, the water supply line is welded to the lid. Furthermore, at least one steam extraction valve is provided to remove steam which has been generated from the water in the interior by heating via the steam extraction valve and in particular to feed it to a further use. The at least one steam extraction valve is thus guided from the outside into the interior of the pressure vessel. For this purpose, the steam extraction valve has a

Steam discharge opening, which projects into the interior of the pressure vessel. The steam extraction valve is led out of the interior sealed and welded in particular on the lid. In particular, a first steam extraction valve with a first steam discharge opening and a second steam extraction valve with a second steam discharge opening are provided, wherein the steam discharge openings are arranged along the pressure vessel longitudinal axis spaced from each other. As a result, a removal of steam from the pressure vessel at different positions, in particular along the pressure vessel longitudinal axis spaced positions, possible. Possibly in the pressure vessel prevailing inhomogeneities of the steam, such as temperature or moisture content, can be compensated. The steam extraction valves are for this purpose brought together by means of a connecting line and discharged together for further use. It is also possible to provide exactly one then discharge valve, which is guided from the outside in the interior of the pressure vessel. A connecting line, which is arranged in particular outside the interior, is unnecessary. The fact that all supply and discharge lines are led out through the lid from the interior, in particular no additional openings and seals in the pressure vessel are required. This means that the pressure vessel can be designed to be particularly compact and robust. This makes it possible to tolerate higher loads in the interior of the pressure vessel. Higher loads may result due to an increased process temperature and / or due to a higher vapor pressure. In particular, the pressure vessel is capable of tolerating temperatures of up to about 400 ° C and especially up to about 450 ° C. A possible operating pressure is at least 3 bar, in particular at least 4 bar and in particular at least 5 bar. The pressure vessel according to the invention is particularly suitable for permanent and in particular for repeated use or steam generation. The effort to seal the pressure vessel is reduced. In particular, the number of required sealing elements is reduced. Advantageously, a steam generator in which the water supply opening and / or the at least one steam discharge opening are arranged in a non-zero, oriented along the pressure vessel longitudinal axis distance to the lid in the interior. In this case, it is possible to supply spatially targeted water needed for steam generation. In particular, the water can be supplied at a position spaced from the lid in the interior of the pressure vessel. The steam generation is thereby more effective. The production of dry steam is improved. In particular, it is also possible to selectively remove steam from the pressure vessel via the steam discharge openings arranged at a distance from the lid.

Particularly advantageous is a steam generator in which the distance of the water supply opening between 20% of a longitudinal extent of the inner space and 80% of the longitudinal extent, in particular between 30% of the longitudinal extent and 70% of the longitudinal extent, in particular between 40% of the longitudinal extent and 60% the longitudinal extent and in particular about 50% of the longitudinal extent is. This makes it possible to supply water in relation to the longitudinal extent of the interior in approximately centrally to the pressure vessel. It has been found that a water supply in this area leads to the fact that the supplied water can be evaporated particularly effectively in dry steam. Depending on the design of the heating element and a water supply via the water supply opening closer to the lid, so with a smaller distance to the lid or at a greater distance, ie with an increased distance to the lid. It is essential that water does not run uncontrollably over an opening arranged in the top of the lid, in particular not at a predetermined location, into the pressure space. Particularly advantageous is a steam generator in which at least two steam discharge openings are provided, wherein a first distance of the first steam discharge opening is smaller than a second distance of the second steam discharge opening, wherein in particular the first distance of the first steam discharge opening between 1% a longitudinal extension of the Numenraums and 20% of the longitudinal extent, in particular between 5% of the longitudinal extent and 15% of the longitudinal extent and in particular about 10% of the longitudinal extent, and wherein the second distance between 5% of the longitudinal extent of the interior and 100% of the longitudinal extent, in particular between 20 % of the longitudinal extent and 90% of the longitudinal extent, in particular between 40% of the longitudinal extent and 70% of the longitudinal extent, in particular between 50% of the longitudinal extent and 60% of the longitudinal extent and in particular about 55% of the longitudinal extent. In particular, it is thus ensured that the steam discharge openings have a mutually different distance to the lid. This ensures that steam is taken at different spatial positions within the interior of the pressure vessel. Possibly existing inhomogeneities of the steam with regard to temperature and / or moisture content can thereby be compensated. Inhomogeneities of the vapor within the pressure vessel may be locally different. Locally dependent inhomogeneities can be compensated and, in particular, equalized by taking the steam at different positions. Location-dependent inhomogeneities of the steam can result, for example, from locally different temperature and / or pressure conditions. In particular, the inhomogeneities can also be time-dependent. The inhomogeneities can be compensated in particular for a permanent removal of steam to be carried out over a longer period of time. A permanent, over a longer period to take place steam extraction can also mean that the steam is not removed continuously, but in portions, for example in a period of one hour zigfach or hundred times a steam extraction for about a few seconds, especially in the form of short bursts of steam. Advantageous is a steam generator in which the heating element is designed as a heating coil, which is fastened in particular on the cover. The heating coil can be arranged concentrically to the pressure vessel longitudinal axis in the interior. As a result, a uniform heating of the volume located in the interior is equally possible. The heating coil allows quick and direct heating of the water. In particular, the heating coil has an enlarged surface.

Particularly advantageous is a steam generator in which the heating coil along the pressure vessel longitudinal axis extends such that a longitudinal extent of the heating coil along the pressure vessel longitudinal axis substantially corresponds to a longitudinal extent of the interior along the pressure vessel longitudinal axis. In particular, the longitudinal extension of the heating coil is at least 95% of the longitudinal extent of the interior, in particular at least 98% and in particular at least 99%. This makes it possible to heat the entire interior quickly and in particular homogeneously. In the interior of sprayed water is evaporated quickly and reliably. In addition, it is possible to evaporate residual condensation water present in the pressure vessel.

According to an advantageous embodiment, the water supply line is arranged concentrically to the pressure vessel longitudinal axis. This ensures that the water to be supplied is centrally introduced into the interior of the pressure vessel.

According to a further advantageous embodiment, the water supply line comprises a water supply nozzle for spraying the water into the interior. The water supply nozzle thus has the water supply opening. The water supply nozzle allows the supply of water in defi- ned and especially small doses. In particular, the supplied water is swirled through the nozzle such that small water droplets are generated and thus the surface of the supplied water is increased. This supplied water mist can be quickly and reliably converted into water vapor by the heated heating coil. The production of water vapor is thus faster and more reliable possible.

According to a further advantageous embodiment, the side wall has a connecting flange. The connecting flange is welded in particular to the side wall. The connecting flange allows the detachable attachment of the lid. The connecting flange is attached to an end facing the cover. The connecting flange has in particular a plurality of threaded bores on the front side for receiving fastening screws for screwing on the cover.

According to a further advantageous embodiment, the steam generator has at least one Meßinstrument- recording, which is mounted on an outer side of the pressure vessel. The fact that the at least one Meßinstrument- recording is arranged on the outside of the pressure vessel, it is not necessary to provide additional holes or openings in the container to supply measuring instruments in the interior. Such feeding into the interior can be dispensed with since the required process temperatures can be measured reliably on the outside. Although the temperatures determined on the outside of the pressure vessel may differ from the process temperatures in the interior. However, such a deviation can be determined as part of a calibration to be performed initially and taken into account for the temperature control during operation of the system. It is also conceivable that one Temperature difference between the outside of the pressure vessel and the interior is so small that the temperature difference is negligible and therefore is not taken into account in the control of the system. According to a further advantageous embodiment, at least one temperature measuring instrument is provided to measure the temperature in the interior of the pressure vessel. In particular, two temperature measuring instruments are provided, in particular two temperature measuring instruments based on different measuring principles. This reduces the risk of incorrect temperature determination.

According to a further advantageous embodiment, a sealing element between the side wall and the lid for improved sealing of the interior is provided. In particular, the sealing element is metallic. In particular, the metallic sealing element is in particular a frontally circumferential annular seal with a C-shaped cross section. Such a seal can be loaded up to about 450 ° C. Alternatively, the sealing element may be a plate spring seal, which is particularly cost-executable. It is also possible to use a flat gasket with graphite and spit sheet insert. Such a seal is available at low cost.

According to a further advantageous embodiment, the steam generator on an insulating cover which surrounds the pressure vessel in particular completely. Completely in this context means that the outsides, so the surfaces of the pressure vessel are completely enclosed by the insulating cover. The insulating cover has only openings to lead out the water supply line and the at least one steam extraction valve. It is particularly advantageous if the insulating cover has a particular inner insulating core layer for abutment against the pressure vessel and a particular external, the insulating core layer enveloping Isulier outer shell. The insulating outer shell serves, in particular, for the protection of the insulating core layer, which is embodied, for example, as a material which is particularly thermally insulating, for example as a plastic foam material. The insulating outer shell serves to protect the insulating core layer. The insulating core layer has in particular a layer thickness which is significantly greater than the layer thickness of the insulating outer shell.

According to a further advantageous embodiment, the insulating cover comprises a support member for supporting the pressure vessel. This ensures that the insulating cover is not damaged due to the weight of the pressure vessel.

According to a further advantageous embodiment, at least one moisture content measuring instrument is provided for measuring the moisture content of the fluid arranged in the interior. The moisture content of the dam is an essential characteristic and therefore the quality of the

Steam central. This can be avoided that, for example, steam is dissipated with too little or too much moisture for further processing. The quality of the steam generation is improved. The moisture content measuring instrument is designed in particular as a weighing device. The weighing device serves to determine a mass difference of the condensed water in the pressure vessel before and after steam generation. From the difference in the mass of the condensed water directly results in the mass of the evaporated water and thus the proportion of water supplied in the steam. It is another object of the present invention to provide a food preparation plant in which steam for food preparation can be provided reliably and with predetermined steaming properties.

The problem is solved by a system with the features specified in claim 14. The essence of the invention is that a plant for food preparation comprises a steam generator according to the invention. The steam generator is connected to an osmosis device. The osmosis device serves to provide water for steam generation. Furthermore, a food container connected to the steam generator is provided in which food is prepared by means of the generated steam. For this purpose, the generated steam is supplied to the food container. The supplied steam is used in particular for heating the food and can particularly advantageously also serve for stirring or mixing the food arranged in the food container.

According to a further advantageous embodiment, a control / regulating unit is provided to control the steam generation in the steam generator and / or to regulate. Additionally or alternatively, the control / regulating unit can serve to control and / or regulate the steam supply into the food container. Both the features specified in the claims and the features specified in the following embodiment of the system according to the invention are each suitable alone or in combination with each other to further develop the subject invention. The respective combinations of features provide with regard to the further fertilize the subject invention is not limiting, but have essentially only exemplary character.

Further features, advantages and details of the invention will become apparent from the following description of an embodiment with reference to the drawing. Show it:

1 is a schematic representation of an arrangement for food preparation,

Fig. 2 is a perspective view of an inventive

Steam generator,

1 is a longitudinal section along section line III-III in Fig. 2, Fig. A side view of a pressure vessel of the steam generator,

Fig. 5 is a plan view of the lid with connecting lines arranged thereon, and

6 is a side view of the lid of FIG .. 5

A highly schematically illustrated plant 1 for food preparation in FIG. 1 comprises an osmosis device 2 for providing water for steam generation. The osmosis device 2 is connected to a steam generator 3 by means of a connecting line 4. The supply of water from the osmosis device 2 in the steam generator 3 is shown by the arrow 5. In the steam generator 3, as will be explained in detail later, 5 steam is generated from the supplied water. Of the Steam is, as symbolically represented by the arrow 6, discharged via a feed line 7 from the steam generator 3. The steam is supplied to a food container 8 connected via the feed line 7 for preparing the food present in the food container 8. In addition, a control / regulation unit 9 is provided. The control / regulation unit 9 serves to control and / or regulate the generation of steam in the steam generator 3 and / or the steam supply into the food container 8. For this purpose, the control / regulation unit 9 via each bidirectional signal connection lines 10 with the osmosis device 2, the steam generator 3 and the food container 8 connected.

Subsequently, the structure of the steam generator 3 according to the invention will be explained in more detail with reference to FIGS. 2 to 6. The steam generator 3 serves to generate water vapor, which can be used in particular for heating and mixing food.

The steam generator 3 comprises a pressure vessel 1 1, which is completely enclosed by an insulating cover 12. The pressure vessel 1 1 is designed substantially cylindrical and has a pressure vessel longitudinal axis 13. At a bottom end shown in Fig. 3 below, the pressure vessel 1 1 has a curved bottom 14. The bottom 14 is welded to a cylindrical tube side wall 15. The side wall 15 is oriented concentrically to the pressure vessel longitudinal axis 13. At an upper end of the side wall 15, opposite the bottom 14, a connecting flange 16 is welded. The connecting flange is designed in particular annular and has in each case parallel to the pressure vessel longitudinal axis 13 oriented, not shown threaded bores, which serve to receive connecting screws. At the connecting flange 16, a lid 17 is screwed. The lid 17 is so detachably connectable connected to the side wall 15. For this purpose, the lid 17 eight through holes 18, can be inserted through the connecting screws for screwing into the threaded holes of the connecting flange 16.

Characterized in that the connecting flange 16 is firmly and permanently welded to the side wall 15, the connecting flange 16 is part of the side wall 15. Between the connecting flange 16 and the cover 17, ie between the side wall 15 and the cover 17, is a sealing element 19th intended. According to the embodiment shown, the sealing element is a metallic sealing element in the form of a ring seal with a C-shaped cross section. It is also conceivable to carry out the metallic sealing element as a plate spring seal. In particular, the metallic sealing element is designed to run circumferentially on the side wall 15.

The bottom 14, the side wall 15 and the cover 17 surround and enclose an interior 20 of the pressure vessel 1 1. In the interior 20, a heating element in the form of a heating coil 21 is arranged. The heating coil 21 is attached to the lid 17 with two connections 39. The terminals 39 serve for the power supply for an electrical heating of the turns of the heating coil 21. In particular, the heating coil comprises twenty-two turns. For example, a power supply of 400V at a power of 3500W is required. The heating coil 21 is arranged concentrically to the pressure vessel longitudinal axis 13 such that the turns of the coil run along a cylinder jacket surface arranged concentrically to the pressure vessel longitudinal axis 13. The cylindrical surface has a diameter of at least 30 mm. This ensures that there is sufficient space in the space covered by the heating del 21 enclosed interior prevails, for example, to arrange further components there. Along the pressure vessel longitudinal axis 13, the heating coil 21 has a longitudinal extension L _H. Along the pressure vessel longitudinal axis 13, its interior 20 has a longitudinal extent Li. In particular, L _H > 0.95 · L _l5, in particular L _H > 0.98 · Li and in particular L _H > 0.99 · L

The steam generator 3 further has a water supply line 22 which is brought out of the interior 20 sealed. For this purpose, the water supply line 22 is welded to the cover 17. The water supply pipe has a water supply nozzle 23 with a water supply opening 24. The water supply nozzle 23 is used for spraying water into the inner space 20 of the pressure vessel 1 1. The water supply line 22 led out from the inner space 20 is connected to the osmosis device 2 via the connecting line 4. The water supply line 22 is arranged concentrically to the pressure vessel longitudinal axis 13. That is, the heating coil 21 is disposed around the water supply pipe 22 on the outside. The water supply line 22 is surrounded by the heating coil 21 at least partially.

In order to ensure a controlled and in particular regulated supply of water via the water supply line 22, the steam generator 3, a solenoid valve 25 and a gear pump 26, which are arranged between the connecting line 4 and the water supply line 22.

At one end remote from the interior 20, the water supply line 22 is fitted with a check valve which prevents steam from passing from the interior 20 to the solenoid valve 25. The check valve blocks the water supply line 22 in a flow direction out of the interior 20 of the pressure vessel 1 1 out. The gear pump 26 can - in contrast to Fig. 2 shown directly on the water supply line 22 moniert - arranged in combination with an expansion vessel and a pressure switch in the region of the connecting line 4 in front of the connected to the osmosis device 2 solenoid valve 25 be. Specifically, the gear pump 26, the expansion vessel and the pressure switch are connected to the control / regulation unit 9. In such an arrangement of the gear pump 26, the pressure vessel 1 1 can be connected to any osmosis device, in particular with an existing osmosis device 2, if only parts of the system 1 to be provided. The expansion device is connected with a pressure difference of about 7 bar to 8 bar to prevent the motor of the gear pump 26 is not overloaded. The metering of the necessary small amounts of water is controlled by the solenoid valve 25.

In the water supply line 22, an unillustrated throttle valve may be provided. The throttle valve causes a throttling of the interior 20 supplied amount of water. In particular, the throttle valve is disposed in a portion of the water supply pipe 22 disposed outside of the inner space 20. Specifically, the throttle valve is disposed in the water supply pipe 22 between the solenoid valve 25 and the lid 17. It is also conceivable that the throttle valve is arranged in the water supply line 22 within the inner space 20. In any case, the throttle valve is disposed in the water supply pipe 22 in front of the water supply nozzle 23. The water supply nozzle 23 is arranged, in particular, at one end of the water supply line 22 within the inner space 20. Characterized in that the reduced in the amount of water supplied, which in the interior 20 of the pressure vessel 1 1 existing Heat sufficient to evaporate the amount of water in the water supply line 22, at least partially. About the water supply nozzle 23 is then at least partially already evaporated water, ie water vapor, supplied to the interior. The supply of water vapor is improved. In particular, over the predeterminable amount of water and the temperature and the pressure within the inner space 20, a complete evaporation of the water supplied within the water supply line 22 can be ensured. The water supply line 22 represents a first steam generating chamber. The first steam generating chamber is located upstream of the inner space 20. The interior 20 represents a second steam generating chamber. Due to the two-stage steam generation, the result, ie the homogeneity of the steam generated and discharged via the steam extraction valves, is improved and its water content is reduced.

For discharging the steam generated in the inner space 20 from the pressure vessel 11, a first steam extraction valve 27 with a first steam discharge opening 28 and a second steam extraction valve 29 with a second steam discharge opening 30 are used in that the steam discharge openings 28, 30 of the two steam extraction valves 27, 29 are arranged at respectively different heights along the pressure vessel longitudinal axis 13. This means that the steam at different height positions in the interior 20 of the pressure vessel 1 1 is removed. The steam extraction valves 27, 29 are connected to each other via a connecting hose 38. The total of the steam taken by means of the steam extraction valves 27, 29 is provided via the feed line 7, not shown in FIG. 2, to a food container. The steam extraction valves 27, 29 are off sealed led out of the interior 20 and welded in particular to the cover 17.

This means that both the water supply line 22 and the two steam extraction valves 27 and 29 are led out of the inner space 20 through the cover 17. In particular, it is not necessary that additional bores and / or openings be provided on the side wall 15 or on the bottom 14. The number of openings is reduced. The number of required seals is reduced. Such a pressure vessel is robust and stable.

In the interior 20, a Ablussrohr 40 is further provided, which is fixed by means of an oval flange 41 on the cover 17. The tube 40 is connected to the oval flange 41 in such a way that the drainage tube 40 does not protrude at the connecting flange 41 at the end. In particular, the drainage pipe 40 is circumferentially welded to the oval flange 41, on an outer cylinder jacket surface of the drainage pipe 40. At a lower end opposite the oval flange 41, the drainage pipe 40 is curved in such a way that a lower opening 42 of the drainage pipe 40 is arranged centrally in the region of a lowest point of the bottom 14 of the pressure vessel 11. The Ablussrohr 40 allows with the thus arranged opening 42 an effective and straightforward suction of condensed water, which collects in the region of the lowest point at the bottom 14 of the pressure vessel 1 1.

The drainage pipe 40 has two functions. When commissioning the system 1, the temperature in the interior 20 is first increased via the heating coil 21. At the same time, the vapor pressure increases. It is possible, thereby the operational readiness of the plant 1 and in particular of the steam generator gers 3 produce. If too much water in the pressure vessel 1 1, the existing amount of water should be too large, for example, by manual intake, an automatic rinsing process can be performed via the drain pipe 40. As a result of the vapor pressure present in the interior 20 of the pressure vessel 11, excess, not yet evaporated water in the region of the lowest point of the bottom 14 is pushed out of the pressure vessel 11 via the opening 42 into the drainage pipe 40 and through the drainage pipe 40. The discharged via the drain pipe 40 water can be advantageously fed to the food container 8. This makes it possible to clean the connecting line 7 between the steam generator 3 and the food container 8 and other components connected thereto. Another function of the exhaust pipe 40 is the possibility of vapor mixing from below or from above. For example, it is possible to change the water content in the inner space 20 of the pressure vessel 1 1 in order to control the quality of the steam. This is done in particular via the steam extraction valves 27 and 29. Steam can also be transported via the drain pipe 40 to the food container 8. In this function, the drainage pipe 40 is a third steam extraction valve. The first steam extraction valve 27 is connected to the drainage pipe 40. The connection between the first steam extraction valve 27 and the drain pipe 40 may also be omitted. In particular, the connection is not mandatory.

At the pressure vessel 1 1, a first measuring instrument receptacle 32 and a second measuring instrument receptacle 33 are provided on an outer side 31. The Meßinstrument- recordings 32, 33 are welded to the outside 31 of the pressure vessel 1 1. The first Meßinstrument- recording 32 serves to receive a resistance sensor. The resistance sensor is used for temperature measurement. At an in Fig. 4 below darge The opening is the first meter 32 receptacle axially limited with a weld drop. There are also other limiting means possible. The second Meßinstrument- recording 33 serves to accommodate a built-in thermostat, which is axially fixed by means of a bead 34. The built-in thermostat is used to monitor the temperature in the interior 20 of the pressure vessel 1 1. The built-in thermostat is electrically switchable. In particular, the built-in thermostat is designed such that it automatically interrupts the further heating of the interior 20 via the heating coil 21 upon reaching an upper temperature threshold, which may be set, for example, at 350 ° C. After falling below a lower one

Temperature threshold, the heating coil 21 is activated again and a heating of the interior 20 continues. For this purpose, the built-in thermostat with the control / egelungseinheit 9 in signal communication. The built-in thermostat and the resistance sensor are temperature measuring instruments for measuring the temperature in the interior 20.

In addition, an unillustrated moisture content measuring instrument can be provided for measuring the moisture content of the fluid arranged in the interior. This makes a moisture measurement and thus a determination of the steam quality possible. In particular, it is possible to maintain a predetermined desired range of moisture content, for example, to add additional water if the desired minimum moisture content is exceeded or to produce higher temperatures for evaporation, if a maximum moisture content is exceeded. The moisture content measuring instrument is in signal connection with the control unit 9.

The insulating cover 12 comprises an inner insulating core layer 35 for direct contact with the pressure vessel 1 1. The insulating core layer is made of a thermally well insulating material, in particular of a plastic foam material. The insulating core layer 35 has in comparison to the pressure vessel 1 1 an increased layer thickness. The insulating core layer 35 is surrounded by an enveloping insulating outer shell 36. The insulating outer shell 36 is thin compared to the insulating core layer. The insulating outer shell 36 serves as protection for the insulating core layer 35. The insulating cover 12 has a support element 37 arranged in the region of the bottom. The support member 37 serves to support the pressure vessel 1 1, in order to avoid that the insulating cover 12 could be damaged due to the weight of the pressure vessel 1 1. In particular, due to the light and soft consistency of the insulating core layer, the support member 37 is advantageous. The support element 37 is arranged concentrically to the pressure vessel longitudinal axis 13. The support member 37 is bolted to the insulating outer shell 36. The pressure vessel 1 1 lies with the bottom 14 loosely on the support member 37. The support member 37 is rigid. The insulating outer shell 36 has a thickness of 1, 5 mm with a container diameter of about 260 mm. The insulating outer shell 36 is made thin-walled. The insulating core layer 35 is made substantially tubular, wherein a wall thickness corresponding to an insulating layer between the pressure vessel 1 1 and the insulating outer shell 36, about 50 mm. This means that the layer thickness of the insulating core layer 35 is about 30 times greater than the layer thickness of the insulating outer shell 36. In particular, the layer thickness of the insulating core layer 35 is about 10 times to 50 times the layer thickness of the insulating outer shell 36, in particular 20 times up to 40 times and especially 30 times to 35 times.

The function of the plant 1 for food preparation and in particular of the steam generator 3 will be explained in more detail below. By means of osmo- se-device 2 osmosis water is supplied to the steam generator 3 with a water pressure of 7 to 8 bar via the solenoid valve 25. The osmosis device 2 is used in particular to filter out ingredients of the tap water. The water provided by means of the osmosis device 2 is about 98% pure water. This means that at most 2% ingredients are present in the water. This ensures the taste neutrality of the food to be produced. In addition, the risk of calcification of the components, in particular the piping systems and the pressure vessel, significantly reduced. A permanent operation of the steam generator 3 and the plant 1 in total would not be possible by means of tap water. In this case, the water is provided by the osmosis device 2 itself with about 3 to 4 bar available, the gear pump 26 increases the pressure on said 7 to 8 bar. The target pressure of 7 to 8 bar can be controlled via the control / regulation unit 9. For this purpose, the gear pump 26 with the control

/ Control unit 9 in signal connection. In particular, the control and / or regulation takes place via an electronic program, in particular via a computer program, ie software-controlled. By means of such Computeφrogramms the water supply in the steam generator can be set arbitrarily, for example by timed running the pump or not operated. The timed pump operation, for example, when reaching a maximum predetermined operating pressure, for example, 5 bar in the interior 20 of the pressure vessel 1 1 are turned off. The operating pressure in the interior 20 is achieved by the formation of steam. In a corresponding, pulsed water supply water in small quantities, ie in small doses, through the water supply line 22 to the water supply nozzle 23 is promoted. In that the water supply pipe 22 is surrounded by the heating coil 21, the Wasserzuführ- line 22 is already heated, so that the subsidized in the water supply line 22 water is also already heated. Accordingly, heated water and / or steam can escape from the water supply port 24 at the water supply nozzle. The water and / or steam emerging from the water supply nozzle 23 is in particular sprayed directly onto the heating coil 21 and converted there into dry steam. The dry steam is taken up via the steam discharge openings 28, 30 in the steam extraction valves 27, 29 and discharged together.

In the method according to the invention for generating steam, the pressure vessel 1 1 is initially heated to 250 ° C. with only a small amount of osmosis water. The pressure in the interior 20 rises at this temperature without water to about 3 bar. From this condition, osmosis water is automatically sprayed in until the pressure has risen to around 5 bar. The compute program can be used to monitor and in particular influence the pressure build-up.

After reaching a predefinable desired temperature and / or a specifiable desired pressure, the heating element 21 can be switched off. Due to the inertia of the systems, in particular due to the inertia of the heating element 21, the heated heating element 21 causes a further increase in temperature and / or pressure in the interior 20 of the pressure vessel 1 1. By means of the drain pipe 40 of this unintentional temperature and / or or pressure increase can be countered, in which a controlled discharge of water vapor is made possible via the outlet pipe 40. The drain pipe 40 is a third steam extraction valve. An additional steam extraction valve is thus unnecessary. Additionally or alternatively, the computer program may be designed such that a shutdown of the heating element 21 takes place before the desired temperature is reached. In particular, depending on the control and regulation behavior of the heating element 21, a temperature threshold value and / or a pressure threshold value can be defined for this, which effects a regulation and in particular a switching off of the heating element 21. As a threshold for the removal of water vapor, for example, be 8 bar.

In addition, an unillustrated pressure relief valve may be provided on the pressure vessel 1 1. The pressure relief valve enables pressure reduction at a predeterminable maximum pressure, such as 10 bar. The predeterminable maximum pressure at which the pressure relief valve triggers is in particular greater than the threshold value for the removal of the steam via the third steam extraction valve 40. It is also conceivable to use the overpressure valve with the third steam extraction valve 40 in an integrated overpressure / steam extraction Valve. Such a valve has a high functional integration. The number of with the pressure vessel 1 1 and in particular with the interior 20 to be connected components is reduced.

Investigations have shown that incurred in the process for generating steam and the subsequent removal of the vapor from the pressure vessel 1 1 about 35g to 45g of condensation. The amount of condensation is low and does not affect steam production or steam discharge. With the stated amount of condensation water, the discharged steam is wet enough to allow sufficient heat transfer to warm up the food. The discharged steam is also dry enough to avoid watering down the food to be cooked. Investigations have shown that with a larger amount of water can dilute the food to be produced. As a result, the quality of the food to be produced may be impaired. With a reduced amount of condensed water, sufficient heat transfer from the discharged steam to the food to be heated is not guaranteed.

It is sufficient if exactly one steam extraction valve is present or used. This may be either the first steam extraction valve 27, the second steam extraction valve 29 or the third steam extraction valve 40. Characterized in that the steam discharge openings 28, 30, 42 of the steam extraction valves 27, 29, 40 are arranged at different height positions in the interior 20 of the pressure vessel 1 1, a targeted steam extraction can take place. In particular, with knowledge of an inhomogeneous distribution of the properties of the steam within the interior 20, steam can be removed with desired properties, in particular temperature and moisture content, via the controlled removal at a specific steam extraction valve.

Studies have shown that the vapor generated in the interior 20 has homogeneously distributed properties. A local dependence is virtually undetectable. As a result, the expenditure on equipment is reduced.

Claims

claims

A steam generator for generating water vapor, wherein the steam generator (3) comprises

a. a pressure vessel (1 1) with

i. a pressure vessel longitudinal axis (13)

ii. a floor (14),

iii. a side wall (15) connected to the floor (14), iv. one with the side wall (15) releasably connectable lid (17),

v. one of the bottom (14), the side wall (15) and the lid (17) surrounded interior (20),

b. a heating element (21) arranged in the interior space (20), c. a water supply pipe (22) led out of the inner space (20) for supplying water into the pressure vessel (11), the water supply pipe (22) having a water supply opening (24) opening into the inner space (20 protruding, d. at least one steam extraction valve (27, 29) led out of the interior space (20) for discharging the steam from the pressure vessel (11), wherein the at least one steam extraction valve (27, 29) has a steam discharge opening (28, 30 ), which projects into the interior space (20),

wherein the water supply line (22) and the at least one steam extraction valve (27, 29) are each led out through the lid (17) from the interior (20).

2. Steam generator according to claim 1, characterized in that the water supply opening (24) and / or the at least one

Steam discharge opening (28, 30) in a non-zero, long the pressure vessel longitudinal axis (13) oriented distance to the cover (17) in the interior (20) are arranged.

Steam generator according to claim 2, characterized in that the distance of the water supply opening (20) between 20% of a longitudinal extent (Li) of the interior (20) and 80% of the longitudinal extent (Lj), in particular between 30% of the longitudinal extent (Li) and 70% of the longitudinal extent (Li), in particular between 40% of the longitudinal extent (Li) and 60% of the longitudinal extent (Li) and in particular about 50% of the longitudinal extent (Li).

Steam generator according to claim 2 or 3, characterized in that at least two steam discharge openings (28, 30) are provided, wherein along the pressure vessel longitudinal axis (13) oriented first distance of the first steam discharge opening (28) is smaller than a along the pressure vessel longitudinal axis (13) oriented second distance of the second steam discharge opening (30), wherein in particular the first distance of the first steam discharge opening (28) between 1% of a longitudinal extent (Li) of the interior (20) and 20% of the longitudinal extent (Li), in particular between 5% of the longitudinal extent (Li) and 15% of the longitudinal extent (Li) and in particular about 10% of the longitudinal extent (Li), and wherein the second distance between 5% of the longitudinal extent (Li) of the interior (20 ) and 100% of the longitudinal extent (Li), in particular between 20% of the longitudinal extent (Li) and 90% of the longitudinal extent (Li), in particular between 40% of the longitudinal extent (Li) and 70% de r longitudinal extent, in particular between 50% of the longitudinal extent (Li) and 60% of the longitudinal extent (Li) and in particular about 55% of the longitudinal extent (Li).

5. Steam generator according to one of the preceding claims, characterized in that the heating element is a heating coil (21), in particular on the cover (17) is fixed, wherein the heating coil (21) in particular along the pressure vessel longitudinal axis (13) , wherein a longitudinal extent (L _H ) of the heating coil (21) along the pressure vessel longitudinal axis (13) substantially corresponds to a longitudinal extent (L ^ of the interior (20) along the pressure vessel longitudinal axis (13), wherein in particular L _H > 0 , 95 ^■ L _l5 in particular L _H > 0.98 ^■ Li and in particular L _H > 0.99 ^■ L

6. Steam generator according to one of the preceding claims, characterized in that the water supply line (22) is arranged concentrically to the pressure vessel longitudinal axis (13). 7. Steam generator according to one of the preceding claims, characterized in that the water supply line (22) comprises a water supply nozzle (23) having the water supply nozzle (23) for spraying water. 8. Steam generator according to one of the preceding claims, characterized in that on the side wall (15) on a cover (17) facing the end face a connecting flange (16) is provided for releasably attaching the lid (17). 9. Steam generator according to one of the preceding claims, characterized by at least one on an outer side (31) of the pressure vessel (1 1) mounted Meßinstrument- recording (32, 33) for receiving in each case a measuring instrument.

10. Steam generator according to one of the preceding claims, characterized by at least one temperature-measuring instrument, in particular two temperature-measuring instruments, for measuring the temperature in the interior (20).

1 1. Steam generator according to one of the preceding claims, characterized by a between the side wall (15) and the cover (17) arranged sealing element (19) for sealing the interior (20), wherein in particular the metallic sealing element (19) one, in particular the front side circumferential, ring seal with C-shaped cross section or a plate spring seal is.

12. Steam generator according to one of the preceding claims, characterized by an insulating cover (12) surrounding the pressure vessel (1 1), in particular completely, wherein in particular the insulating cover (12) has an insulating core layer (35) for abutment on the pressure vessel (1 1) and the insulating core layer (35) enveloping insulating outer shell (36), and wherein in particular the insulating cover (12) has a support member (37) for supporting the pressure vessel (13).

13. Steam generator according to one of the preceding claims, characterized by at least one moisture content measuring instrument for measuring the moisture content of the interior (20) arranged fluid.

14. Plant for preparing meals comprising

a. a steam generator (3) according to one of the preceding claims, b. an osmosis device (2) connected to the steam generator (3) for providing water for steam generation, c. a food container (8) connected to the steam generator (3) to which the generated steam is supplied for preparing food.

Installation according to claim 14, characterized by a control unit (9) for controlling and / or regulating the generation of steam in the steam generator (3) and / or the steam supply to the food container (8).