WO2000004969A1

WO2000004969A1 - Method and device for separating emulsions from process and/or waste water

Info

Publication number: WO2000004969A1
Application number: PCT/EP1999/005012
Authority: WO
Inventors: Michael Betz; Matthias Nomayo
Original assignee: Michael Betz; Matthias Nomayo
Priority date: 1998-07-22
Filing date: 1999-07-15
Publication date: 2000-02-03
Also published as: DE19832916A1; DE19981352D2; AU5159899A; PE20001163A1

Abstract

The invention relates to a method and a device for separating process and/or waste water having a defined concentration of coagulable constituents into a hydrophobic phase and a clear phase. The waste water to be separated is filled into a vessel (1) on the head side and withdrawn in the bottom area. The waste water filled into the vessel is heated from the base of the vessel (1) so as to create temperature inversion layers in said vessel (1). The hydrophobic constituents coagulate as they descend to a defined depth which corresponds to a coagulation layer and as a result of the inverse temperature gradient from there rise to the hydrophobic phase situated near the surface, where they are skimmed off. Below the coagulation layer the clear phase forms near the bottom, where it is withdrawn.

Description

METHOD AND DEVICE FOR SEPARATING EMULSIONS FROM PROCESS AND / OR WASTE WATER

Description:

The invention relates to a method for separating process and / or waste water with a predetermined concentration of coagulable, hydrophobic constituents into a hydrophobic phase and a clear phase.

In the case of waste water with a high concentration of coagulable, hydrophobic constituents, there is the problem that these constituents or constituents cannot be separated by customary processes, such as, for example, B. Sieve, filter or press to separate from the rest of the wastewater. It is therefore not possible to separate the phases into a hydrophobic phase and a clear phase. This also applies in the event that flotation or sedimentation processes are used.

This applies in particular to blood-containing waste water from the fish meal industry. Such waste water has an organic solids content of more than 3% by weight. Even at the aforementioned concentrations, there is no longer a possibility (by means of flotation or similar processes) of concentrating the ingredients in question so that they can be skimmed off in the hydrophobic phase.

DE-C 30 11 025 has disclosed a process for separating, if appropriate with degreasing, solids, in particular organic substances, from liquids, the liquids containing solid substances which can be aggregated and / or dewatered by the action of heat. In the known method, by aggregating particles in the liquid and / or reducing the water content thereof by the action of heat and then separating

REPLACEMENT SHEET (RULE 23) the particles worked out of the liquid and drying. A corresponding system is equipped with a collection container, a quick heater and a heat treatment unit.

The invention is based on the technical problem of specifying a process for the separation of process water and / or waste water with a predetermined concentration of coagulable, hydrophobic constituents of the type described at the outset, which provides a perfect separation of the hydrophobic phase and clear phase - even at a high concentration of coagulable, hydrophobic components organic components - enables. In addition, a particularly suitable system should be specified.

To solve this technical problem, the invention relates to a process for separating process and / or waste water with a predetermined concentration of coagulable, hydrophobic constituents into a hydrophobic phase and a clear phase with the following process steps:

the wastewater to be separated is poured into a container, especially a concentration tank, at the top and drawn off as clear water in the bottom area;

the filled wastewater is heated on the foot side of the container by setting an inverse temperature stratification with at least two layers of different temperature in the container;

the hydrophobic components coagulate when sinking in a predetermined coagulation layer height and rise from there due to the inverse temperature gradient to the near-surface hydrophobic phase, where they are skimmed off;

below the coagulation layer height, the clear phase near the ground forms, which is subtracted.

It is usually carried out in such a way that the wastewater is discharged just below the surface in the tank, within the framework of a uniform, non-turbulent flow. The clear water in the bottom area is drawn off evenly and not turbulently, so as not to endanger the temperature stratification that arises due to the turbulence that forms in the tank.

To adjust the inverse temperature stratification, a heater adapted to the cross section of the container is provided, which, for. B. is heated by means of steam or electrical energy. There are usually three layers. The inverse temperature stratification is generally set so that temperatures between 80 ° C. to 95 ° C. are established in the layer immediately above the heating device, temperatures between 55 ° C. and 75 ° C. are present in the area of the layer with the coagulation layer height and Finally, temperatures of approx. 30 ° C to 50 ° C can be reached in the near-surface layer, the temperature stratification being set as a function of the nature and quantity of the waste water introduced and the coagulation temperature of the hydrophobic constituents. In particular, the temperature stratification is largely set in a controlled manner, at least the temperature of a layer and the amount of incoming wastewater being used as control input variables and the heating energy required for heating the heating device being used as a control variable. A convection counteracting the temperature stratification is preferably prevented by baffles arranged in the direction of the temperature gradient of the layers.

Overall, continuous or discontinuous operation is possible. For this purpose, work is carried out with a continuous inflow and outflow of the waste water or clear water or with a corresponding discontinuous inflow and outflow of the waste water or clear water in the so-called "batch" mode. If the wastewater is saline, the invention recommends introducing fresh water into the container near the surface in order to reduce the salt content of the hydrophobic phase.

The invention is based first of all on the knowledge that waste water contaminated with coagulable, hydrophobic, organic constituents not only damage the environment, but that the abovementioned organic constituents can be advantageously recovered. These organic components can be proteins that are produced in fish meal production. Nowadays, these proteins are discharged into the sea with virtually no clarification and contribute to a not inconsiderable level of pollution. They are also irretrievably lost for further processing and accordingly represent an economic loss in fish meal processing. The invention has now recognized that these hydrophobic organic constituents, ie insoluble sediments, usually coagulate within a certain temperature range, in other words can be converted into sedimentable precipitates by physicochemical processes. This means that the previously dispersed to colloidal hydrophobic constituents experience, as it were, particle enlargement. This coagulation process takes place in a specific layer of the container, the coagulation layer height. In the case of proteins, the coagulation temperature, ie the temperature at which the aforementioned coagulation process begins, is approximately 60 ° C to 70 ° C.

The filled waste water is generally heated on the foot side of the container by means of steam bubbles which emerge from the heating device, rise in the container and give off energy while heating. The height of the container is dimensioned such that the vapor bubbles have disappeared or been resorbed or converted at the top of the container. The desired inverse temperature stratification is achieved by the (cold or colder) waste water filled in at the head, the heating on the foot side and the constant removal of the waste water from the floor area, as will be explained in more detail with reference to the figure description. In other words, a relatively cold wastewater layer forms in the upper region of the tank (on the head side), which is constantly supplied with fresh water. The warmer water layers underneath tend to rise within the tank through convection.

However, this is (for the most part) due to the waste water discharge in the (below, hot or warm) clear phase and, on the other hand, compensated in such a way as a result of the (cold) wastewater constantly coming in (from above) that the desired temperature stratification occurs.

As is known, protein molecules consist of hundreds to thousands of amino acid residues which are linked to one another by peptide bonds. This means that, like cellulose and starch, proteins are macromolecular natural substances with molecular weights between 10,000 and several million. Proteins that are absorbed by water form colloidal solutions because the diameter of their molecules is 10 to 10 cm; accordingly, they do not diffuse through a membrane and can therefore be separated out (up to a certain concentration in water) using membrane filters.

The invention now enables a perfect separation into the hydrophobic phase and the clear phase. The proteins change their coagulation layer height when they clot or coagulate, their structure and their chemical and physical properties

Properties and can float close to the surface in the container due to the inverse temperature stratification. This flotation process succeeds without the usual air injection simply because the hydrophobic suspended particles or flakes, which are specifically lighter (than the process or waste water), can rise to the hydrophobic phase. In contrast, their movement in the opposite direction is inhibited. This can be attributed to the energy gain of the suspended particles or flakes by convection. As a result, the inverse temperature stratification achieved according to the invention in still water represents a metastable equilibrium, from which the specifically lighter, suspended particles or flakes can rise in an improved manner while gaining energy, while their movement is inhibited in the opposite direction. This results in a flotation effect which, on the one hand, leads to an improved concentration of the hydrophobic constituents in the flotate or in the hydrophobic phase and, on the other hand, requires a sharp dividing line between the flotate or hydrophobic phase and the clear (water) phase. Due to the above-mentioned principle of the process, especially with process or waste water with a high content of e.g. B. blood proteins compared to currently conventional flotation processes with, for example, chemical or thermal coagulation, an improved separation of the hydrophobic constituents at a higher organic dry matter content in the organic substance between clear water and flotate is achieved. This means that the skimmed off hydrophobic phase can be processed further to a dry substance which has a high organic content and is therefore particularly suitable for (fish meal) processing. The invention also relates to a device which is particularly suitable for carrying out the method described and is described in claims 10 to 17.

In the following, the invention is explained in more detail with reference to a drawing showing only one embodiment; show it:

Fig. 1 shows the device according to the invention and Fig. 2 shows a plant for wastewater treatment, which has the device of FIG. 1.

The figures show a device for separating process and / or waste water with a predetermined concentration of coagulable, hydrophobic constituents into a hydrophobic phase and a clear phase. In its basic construction, this device has a (rotationally symmetrical) cylindrical container 1, in particular a concentration tank 1, with a (waste) water inlet 2 at the head. The container 1 or concentration tank 1 has a conical base 3 with a sediment discharge 4. In addition, there is a heating device 5 arranged on the foot side in the container 1. This heating device 5 has (not shown) internal (flow) holes for (water) steam and is supplied with the required heating energy via a control device 6. Of course, an electrical or other type of heating of the heating device 5 is also possible. The aforementioned heating device 5 serves to set the previously described inverse temperature stratification in the container 1 with layers A, B and C of different temperatures in the container 1.

According to the exemplary embodiment, the (throughflow) bores in the heating device 5 are made in a sintered plate and are dimensioned such that this sintered plate or the heating device 5 leave vapor bubbles with a diameter of approximately 2 mm and below and rise in the container 1. Of course, the use of an end plate drilled by means of laser beams is also conceivable at this point, as long as appropriately small steam bubbles be generated. These ensure the necessary energy transfer to the filled wastewater, which is heated by means of steam at a temperature of approx. 100 ° C (pressure: 1.1 bar) in the manner described below. It has been found that a height of approximately 2.50 m is sufficient for the container 1 to be able to represent the desired heat transfer from the steam to the waste water with the help of the steam bubbles. It has also been shown that this transfer is relatively independent of the temperature difference between the steam (approx. 100 ° C) and the filled waste water (approx. 30 - 50 ° C). So it is regularly ensured that this wastewater in the area of the heating device 5 and above is heated by approximately 10 ° C. to 50 ° C., preferably approximately 20-30 ° C.

In the present case, roughly three layers A, B and C can be distinguished. Temperatures between 80 ° C. and 95 ° C. are usually reached in the layer A arranged directly above the heating device 5. For this purpose, the heating device 5 is acted upon accordingly by the control device 6. The temperature reached is reported back via temperature sensors 7, which are arranged on the inner wall side of the container 1 and are connected to the control device 6. According to the exemplary embodiment, each layer A, B and C is assigned its own temperature sensor 7.

Layer B, which forms above layer A, has temperatures between 55 ° C. and 75 ° C. The coagulation of the hydrophobic constituents of the waste water takes place in this second layer B, specifically at a certain coagulation layer height, which ultimately depends on the low temperature of the components. In any case, the inverse temperature stratification in the container 1 is set so that the coagulation layer height is arranged approximately in the middle of the rotationally symmetrical cylinder container or concentration tank 1.

This is followed by layer C with temperatures of approx. 30 ° C to 50 ° C, in which the hydrophobic phase forms on the surface. In order to be able to skim off the flakes that form, a skimmer 8 near the surface, according to the exemplary embodiment a rotating paddle 8 with an overflow 9, is realized for the flotate. While the hydrophobic phase consequently forms in layer C, the clear phase or clear water phase is arranged in layer A, so that a sharp separation of the two phases is achieved. For the rest, a clear water drain 10 is provided in the area of the clear phase.

In order to set the inverse temperature stratification as stable as possible, the heating device 5 is designed as a circular disk adapted to the cylinder cross section of the container or concentration tank 1. In addition, there are two hollow cylinders 11 with openings 12 to prevent a convection that counteracts the temperature stratification. Since the heating energy required for heating the heating device 5 depends on the water inflow (and its temperature), a corresponding measuring device 13 is provided in the (waste) water inlet 2, which determines the temperature and flow of the water. Like the temperature sensors 7, this measuring device 13 is connected to the control device 6. The aforementioned devices 7, 13 provide control input variables for the control device 6, which controls the heating energy supplied to the heating device 5 on the output side as a function thereof. Accordingly, the heating energy supplied is the manipulated variable of the control device 6. Also indicated is the further possibility of controlling the water outflow via the clear water drain 10 in terms of quantity and / or temperature, which can also be done via the control device 6. The same applies with regard to the skimming device 8. These additional options are represented by dashed connecting lines to the control device 6 in FIG. 1. It is always ensured that the temperature and amount of the waste water supplied via the water inlet 2 as well as the temperature and amount of the clear water discharged by means of the clear water drain 10 are set such that the temperature profile described is obtained. Of course, the water drawn off by means of the skimming device 8 is also taken into account, although its effect is marginal due to the small amount.

To display the inverse temperature stratification, it is generally also necessary to work with containers 1 whose volume is below 1 m ³ , preferably below 0.6 m ³ . At a height of 2.50 m, the base area according to the exemplary embodiment is approximately 0.1 m ² , so that a volume content of approximately 0.3 m ^{3 is} established. Alternatively, a container 1 in the form of a round concentration tank 1 with approximately 1 m can also be used

Diameter can be used, which is evenly in four 90 ° circle segment sections with approximately 0.5 m edge width is divided. The floor space realized in this way is approx. 0.2 m ² , so that there is a volume of approximately 0.5 m ³ .

In addition, square shapes of the container or concentration tank 1 with the aforementioned base area of approximately 0.1 m ² (or also above) are also conceivable. This embodiment offers itself due to the small space requirement and the representation of batteries on containers or concentration tanks 1. Of course, honeycomb, ie hexagonal, configurations are also conceivable.

Instead of the rotating paddle or the skimming device 8, a suction pump with a possibly connected suction nozzle can also be provided in order to be able to remove the flakes which form or the hydrophobic phase. The amount of wastewater drawn off in relation to the amount of water in the concentration tank 1 is adjusted so that a larger amount is drawn off on the foot side via the clear water drain 10 than with the aid of the pump device described above. This is necessary in order to maintain the inverse temperature stratification described unchanged.

Finally, it is conceivable that an inert gas is supplied via the heating device 5 in addition to the (hot) water vapor. This supports the floating of the coagulate. This inert gas can be air, which is added to the water vapor in small quantities. Hydrogen is even more suitable here, because of its special adsorption capacity and the achievable rate of buoyancy due to the low Weight. Of course, CO ₂ or nitrogen can also be used in the present case.

2 shows a flow diagram of a wastewater treatment in connection with the previously described device with inverse temperature stratification. An input buffer 14 with sludge discharge (dashed line) is provided on the input side. In the example described, the wastewater drawn off from this has a temperature of approximately 20 ° C. and a protein content of approximately 4% by weight. It also contains about 3% by weight fish oil. This (waste) water is heated via two heat exchangers 15, 16 to temperatures of approximately 30 ° C. after the first heat exchanger 15 and approximately 50 ° C. after the second heat exchanger 16. The (waste) water then passes through the (waste) water inlet 2 into the container or concentration tank 1. The inverse temperature stratification already described and the associated metastable equilibrium are established. The average temperature of the (waste) water in concentration tank 1 is approx. 70 ° C.

In the present case, the heating device 5 is heated with steam. On the output side, a flotate is drawn off via the overflow 9, which has about 8% by weight of protein and about 7% by weight of fish oil. This flotate has a temperature of approx. 40 ° C to 50 ° C. Following this, the flotate is heated to approximately 70 ° C. by means of a third heat exchanger 17 and fed to a coagulator 18 and a tricanter 19. The tricanter 19 is used to concentrate the protein and to separate (fish) oil and water. Some of the proteins not coagulated in the water are removed from the tricanter 19 and, if necessary, returned to the concentration tank 1. The concentrate from the tricanter 19 is fed to further processing and has more than 20% by weight of protein in the dry substance. The branch leaving Tricanter 19 also represents the separated (fish) oil.

The clear water obtained from the concentration tank 1 is drawn off via the clear water drain 10 and the heat exchanger 16 and only has about 1% by weight of organic constituents.

If the (waste) water is saline, fresh water can be introduced into the concentration tank 1 near the surface in order to achieve a reduction in the salt content of the hydrophobic phase, which would be disadvantageous in the subsequent treatment to the end product.

Claims

Patent claims:

1. Process for separating process and/or wastewater with a given concentration of coagulable, hydrophobic components into a hydrophobic phase and a clear phase with the following process steps:

1.1) The wastewater to be separated is filled at the top into a container (1), in particular a concentration tank (1), and in the bottom area as

Clear water withdrawn;

1.2) the filled waste water is placed at the foot of the container (1) while setting an inverse temperature stratification with at least two layers

(A, B and C) are heated at different temperatures in the container (1);

1.3) the hydrophobic components coagulate as they sink in a predetermined coagulation rate

layer height and from there rise due to the inverse temperature gradient to the hydrophobic phase near the surface, where they are skimmed off;

1.4) Below the coagulation layer height, the clear phase near the bottom forms and is drawn off.

2. The method according to claim 1, characterized in that the wastewater is introduced just below the surface that appears in the container (1), namely as part of a uniform, non-turbulent flow.

3. The method according to claim 1 or 2, characterized in that the clear water in the bottom area is drawn off evenly and not turbulently.

4. The method according to any one of claims 1 to 3, characterized in that a heating device (5) adapted to the cross section of the container (1) is provided to adjust the inverse temperature stratification, which z. B. is heated using steam or electrical energy.

5. The method according to one of claims 1 to 4, characterized in that there are essentially three layers (A, B, C), the inverse temperature stratification being set so that in the layer (A) is immediately above the heating device (5) Set temperatures between 80 °C and 95 °C, in the area of the layer (B) with the coagulation layer height there are temperatures between 55 °C and 75 °C and finally in the layer close to the surface (C) there are temperatures of approx. 30 °C to 50 °C can be achieved, with the temperature stratification being adjusted depending on the nature and quantity of the wastewater filled in and the coagulation temperature of the hydrophobic components.

6. The method according to one of claims 1 to 5, characterized in that the temperature stratification is set in a controlled manner, with at least the temperature of one layer (A, B and C) and the amount of incoming wastewater as control input variables and those for heating the heating device (5 ) required heating energy can be used as a manipulated variable.

7. The method according to one of claims 1 to 6, characterized in that convection counteracting the temperature stratification is prevented by baffles (11) arranged in the direction of the temperature gradient of the layers (A, B, C).

8. The method according to one of claims 1 to 7, characterized in that work is carried out with continuous inflow and outflow of the wastewater or clear water or discontinuously in "batch" operation.

9. The method according to any one of claims 1 to 8, characterized in that the wastewater contains salt and fresh water is introduced into the container (1) close to the surface in order to achieve a reduction in the salt content of the hydrophobic phase.

10. Device for separating process and/or wastewater with a predetermined concentration of coagulable, hydrophobic components into a hydrophobic phase and a clear phase, for carrying out the method according to one of claims 1 to 9

10.1) a container (1), in particular a concentration tank (1), with a (drain) water inlet (2) at the top,

10.2) a heating device (5) arranged on the foot side in the container (1) for adjusting the inverse

Temperature stratification with at least two layers (A, B, C) different temperatures in the container (1),

10.3) a skimming device (8) close to the surface, e.g. B. paddle (8), for skimming the hydrophobic components from the hydrophobic phase, and with

10.4) a bottom-side clear water outlet (10) below the coagulation layer height.

11. The device according to claim 10, characterized in that the container (1) is designed as a rotationally symmetrical cylindrical container with a conical bottom (3).

12. The device according to claim 10 or 11, characterized in that the heating device (5) is designed as a circular disk adapted to the cylinder cross section.

13. Device according to one of claims 10 to 12, characterized in that the heating device (5) is on the inside

Has holes for the application of (water) steam.

14. Device according to one of claims 10 to 13, characterized in that at least one hollow cylinder (11) is provided as a guide plate (11) with openings (12) to prevent convection that counteracts the temperature stratification.

15. Device according to one of claims 10 to 14, characterized in that at least one temperature sensor (7) is attached to the inside wall of the container (1) in order to detect the inverse temperature stratification.

16. Device according to one of claims 10 to 15, characterized in that a flow measuring device (13) is arranged in the (waste) water inlet (2) in order to determine the wastewater flow.

17. Device according to one of claims 10 to 16, characterized in that a control device (6) is implemented, to which the temperature sensor (7) and the flow measuring device (13) are connected on the input side and the heating device (5) on the output side.

CHANGED REQUIREMENTS

[received by the International Bureau on December 21, 1999 (12/21/99); original claims 1-17 replaced by new claims 1-18 (5 pages)]

1.1) the wastewater to be separated is filled at the top into a container (1), in particular a concentration tank (1), and drawn off in the bottom area as clear water;

1.2) the filled waste water is heated at the foot of the container (1) by setting an inverse temperature stratification with at least two layers (A, B and C) of different temperatures in the container (1);

1.3) the hydrophobic components coagulate as they sink to a predetermined coagulation layer height and from there rise due to the inverse temperature gradient to that near the surface

Hydrophobic phase where they are skimmed off;

2. The method according to claim 1, characterized in that the wastewater is located just below the container (1). surface is introduced, within the framework of a uniform, non-turbulent flow.

4. The method according to any one of claims 1 to 3, characterized in that to adjust the inverse temperature stratification a heating device (5) adapted to the cross section of the container (1) is provided, which z. B. is heated using steam or electrical energy.

5. The method according to claim 4, characterized in that via the heating device (5) next to the (hot) (water)

Steam is an inert gas, e.g. B. air is supplied in small quantities.

6. Method according to one of claims 1 to 5, characterized in that essentially three layers (A, B,

C) are present, the inverse temperature stratification being adjusted so that temperatures between 80 ° C and 95 ° C are set in the layer (A) immediately above the heating device (5), in the area of the layer (B) with the coagulation layer height Temperatures between 55 ° C and 75 ° C are present and finally in the layer near the surface (C) temperatures of approx. 30 ° C to 50 ° C are reached, with the temperature stratification depending on the nature and amount of the wastewater filled in and the coagulation temperature of the hydrophobic components are adjusted.

7. The method according to one of claims 1 to 6, characterized in that the temperature stratification is set in a controlled manner, with at least the temperature of one layer (A, B and C) and the amount of incoming wastewater as control input variables and those for heating the heating device (5 ) required heating energy can be used as a manipulated variable.

8. The method according to one of claims 1 to 7, characterized in that convection counteracting the temperature stratification is prevented by baffles (11) arranged in the direction of the temperature gradient of the layers (A, B, C).

9. The method according to one of claims 1 to 8, characterized in that work is carried out with continuous inflow and outflow of the wastewater or clear water or discontinuously in “batch” operation.

10. The method according to any one of claims 1 to 9, characterized in that the wastewater contains salt and fresh water is introduced into the container (1) close to the surface in order to achieve a reduction in the salt content of the hydrophobic phase.

11. Device for separating process and/or wastewater with a predetermined concentration of coagulable, hydrophobic components into a hydrophobic phase and a clear phase, for carrying out the method according to one of claims 1 to 10

10.1) a container (1), in particular concentration tank (1), with a (drain) water inlet (2) at the top,

10.2) a heating device (5) arranged on the foot side in the container (1) for setting the inverse temperature stratification with at least two layers (A, B, C) of different temperatures in the container (1),

10.3) baffles (11) arranged in the direction of the temperature gradient of the layers (A, B, C) in order to prevent convection that counteracts the inverse temperature stratification,

10.4) a skimming device (8) close to the surface, e.g. B. paddle (8), for skimming the hydrophobic components from the hydrophobic phase, and with

10.5) a bottom-side clear water outlet (10) below the coagulation layer height.

12. Device according to claim 11, characterized in that the container (1) is rotationally symmetrical

Cylindrical container is formed with a conical bottom (3).

13. Device according to claim 11 or 12, characterized in that the heating device (5) is designed as a circular disk adapted to the cylinder cross section.

14. Device according to one of claims 11 to 13, characterized in that the heating device (5) has internal bores for the application of (water) steam.

15. Device according to one of claims 11 to 14, characterized in that at least one hollow cylinder (11) is provided as a guide plate (11) with openings (12) to prevent convection that counteracts the temperature stratification.

16. Device according to one of claims 11 to 15, characterized in that at least one temperature sensor (7) is attached to the inside wall of the container (1) in order to detect the inverse temperature stratification.

17. Device according to one of claims 11 to 16, characterized in that a flow measuring device (13) is arranged in the (waste) water inlet (2) in order to determine the wastewater flow.

18. Device according to one of claims 11 to 17, characterized in that a control device (6) is implemented, to which the temperature sensor (7) and the flow measuring device (13) are connected on the input side and the heating device (5) on the output side.