EP2389557A2

EP2389557A2 - Heat accumulator

Info

Publication number: EP2389557A2
Application number: EP10705564A
Authority: EP
Inventors: Günter Richter
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-01-19
Filing date: 2010-01-19
Publication date: 2011-11-30
Also published as: WO2010081908A3; KR20110112815A; CN102264531A; WO2010081908A2

Abstract

The invention relates to a thermal energy accumulator (10, 50, 70, 80, 90) that comprises a large-volume storage tank (12) for storing a storage medium (18) and that is arranged in the ground during use, wherein the storage tank (12) comprises an inner tank (14) and an outer tank (16). The inner tank (14) is made of a temperature-resistant thermoplastic plastic, and the outer tank (16) is made of a pressure-resistant thermoplastic plastic. A thermally insulating material is arranged in an intermediate space (20) between the inner tank (14) and the outer tank (16).

Description

heat storage

The invention relates to a heat accumulator, comprising a large-volume storage container for storing a storage medium, in particular hot water, and to processes for its production.

The operation of heating systems or the provision of hot water is often done with the help of heat storage. In principle, a heat storage heat from a heat source, such as a solar system, record and store long term. If necessary, the stored energy can be removed from the heat storage again and used, for example, for heating.

From DE 2005 037 997 A1, a heat accumulator is known which comprises at least one storage container arranged in the ground, the storage container being formed from a pressure-resistant material and surrounded by a heat-insulating, pressure-resistant material. One way of designing heat accumulators is to construct the heat accumulators to include an inner container, an outer container, and a thermal insulation disposed between the inner and outer containers. The inner container is designed such that it withstands the internal pressure caused by the storage medium accommodated in the heat accumulator. The heat insulation is arranged without pressure around the inner container. Neither the heat insulation nor the protective outer shell serving as a protective cover take up a significant part of the internal pressure. The internal pressure is thus almost completely absorbed by the inner container. If the inner container is made of plastic, then it must have a very large wall thickness in order to have sufficient strength to withstand the internal pressure permanently. The higher the temperature of the storage medium stored in the heat accumulator, the greater the necessary wall thickness. From a creep-internal pressure diagram of a thermoplastic material it can be seen that over the time axis temperature-dependent, the comparison voltage decreases. The higher the temperature, the lower the comparison voltage for the same service life. The thus required large wall thicknesses of the inner container are disadvantageous, since the weight of the heat accumulator is thereby increased, which makes handling difficult and transport costs are increased, higher costs incurred by the higher material consumption and thus the outer diameter of the heat accumulator is relatively large. If the heat accumulator is intended for use in a house, its outside diameter may advantageously not exceed the standard door width of 79 cm. A large wall thickness thus causes the inner diameter of the heat tank is reduced and thus the maximum volume of the heat accumulator is limited. It is an object of the invention to provide a large-volume heat storage, which is inexpensive in construction and relatively easy to produce and can store heat efficiently over a longer period of time.

This object is solved by the features of claim 1. Advantageous developments of the invention are specified in the dependent claims.

According to the invention, the large-volume storage container of the heat accumulator comprises an inner container and an outer container, wherein the inner container made of a temperature-resistant thermoplastic material and the outer container is made of a pressure-resistant thermoplastic material. In a space between the inner container and the outer container, a pressure-resistant, heat-insulating material is arranged.

It is advantageous if the wall thickness of the outer container is greater than the wall thickness of the inner container. In particular, it is advantageous if the outer container, the inner container and the heat-insulating material are designed in such a way that a pressure exerted on the heat accumulator is absorbed essentially by the outer container. Such a pressure exerted on the heat accumulator is, in particular, an internal pressure exerted by the storage medium accommodated in the heat accumulator. Alternatively or additionally, an external pressure can act on the heat accumulator. This is particularly the case when the heat storage is absorbed in the soil and is not or only partially filled with a storage medium. Characterized in that the pressure substantially from the outer container and not or only to a small extent by the inner container and the heat insulating is received material, it is achieved that the sum of the wall thicknesses of the outer container and the inner container is lower than if the pressure would be absorbed only by the inner container. From a creep internal pressure diagram of a thermoplastic material, it follows that the lower the temperature, a smaller wall thickness is needed to accommodate the same pressure. Since the inner container has almost the temperature of the storage medium, but the outer container, however, only the room temperature or the temperature of the soil in which it is located, the required summed wall thickness is lower. The reduced summed wall thickness reduces the weight of the heat accumulator and reduces material costs. Here, the material costs can be reduced to about 50%. Furthermore, such lower wall thicknesses can be more easily controlled in terms of manufacturing technology, and transport and the associated transport costs are facilitated due to the low weight. Furthermore, a low cooling time of the inner and outer container is achieved in the manufacturing process.

Furthermore, it is advantageous that the plastic from which the outer container is formed, is suitable to be received in the ground. As a result, the heat storage can be arranged to save space in the ground.

A particular advantage of the heat accumulator according to the invention is that the storage container can be produced in a particularly simple and inexpensive manner, since the production of the storage container, which is to be formed from a low-cost, thermoplastic material can be done in a relatively easy to carry out B las molding process. In an advantageous embodiment of the invention, the storage container substantially in the form of a sphere, an ellipsoid of revolution or a cylinder. Preferably, the spherical shape when used in the soil to choose because due to the ratio of surface area to volume, the ball the least heat loss can be expected and the ball can demonstrate a high compressive strength at the same time.

The temperature-resistant plastic of the inner container is preferably polypropylene (PP) or polyethylene (PE), since PP or PE has a heat resistance up to 95 ° C and is thus adapted to the temperature conditions of the storage medium, if the inner container, for example, for receiving of hot water is used. This has the advantage that in the manufacture of the inner container, the wall thickness of the inner container can be relatively thin and thus material costs can be saved.

The pressure-resistant plastic of the outer container is preferably polyethylene (PE), a thermosetting plastic or a plastic reinforced with glass fibers (GRP).

The heat-insulating, pressure-resistant material of the intermediate layer between the outer container and the inner container is a rigid foam, preferably polyurethane (PU) ₅ since polyurethane may have a strength which is in the pressure conditions in the inner container, which are in the range of 100 to 200 kPa , is adjusted

Furthermore, it is advantageous that the outer container comprises at least a first part and a second part. It is particularly advantageous if these parts have a maximum dimension in a direction smaller than 79 cm, for example each maximum 79 cm long. In this way, the parts of the outer container can be easily transported through a standard door with a width of 79 cm. Due to the structure of the outer container of several parts, a larger filling volume of the heat accumulator can be realized and this heat storage can still be easily transported into interiors.

Another aspect of the invention relates to a method for producing a large-volume storage element for storing heat energy, in which an inner container made of thermoplastic material is produced in a blow molding process. In a further blow molding process, an outer container with a larger diameter than the inner container made of thermoplastic material. The outer container is divided into at least two parts. These parts are arranged at a predetermined distance from the outer surface of the inner container with a gap therebetween. Subsequently, the parts of the outer container are interconnected and the space between the inner container and outer container is filled with plastic foam material.

A further aspect relates to a further method for producing a large-volume storage container for storing heat energy, in which in a blow molding process, an inner container made of thermoplastic material and in a further blow molding at least two parts of an outer container with a larger diameter than the inner container made of thermoplastic material , On the inside of the parts of the outer container, which faces the inner container in the assembled state, a layer of plastic foam material is applied in each case in a foaming process, which is dimensioned such that an intermediate region between the inner container and the outer container is at least partially filled by this layer. The parts of the outer container are arranged around the inner container and then connected to each other.

It is particularly advantageous if the inner container and the parts of the outer container are transported individually to the place where the storage container is to be set up, and assembled there. In this way, the transport of the heat accumulator or the individual components of the heat accumulator is simplified and the parts can be easily transported through doors or other smaller openings.

The parts of the outer container are preferably connected to each other via at least one screw connection formed by at least one external thread and at least one internal thread. The threads can be easily formed during the manufacture of the parts in the blow molding process. Furthermore, such a screw connection when disassembling a heat storage can be solved non-destructive.

Alternatively, the parts of the outer container may be interconnected by a clamping ring.

The method claims relate to manufacturing processes for the various products according to the invention, as defined in the patent claims on the basis of structural and functional characteristics. To specify the manufacturing steps for different product examples, these features can be included. The invention will be explained below with reference to embodiments in conjunction with drawings. It shows:

FIG. 1 shows a simplified sectional illustration of a heat accumulator arranged in the ground,

FIG. 2 is a detailed sectional view of the heat accumulator according to FIG. 1 in a neck region;

3 is a simplified sectional view of three heat accumulators of different volumes,

FIG. 4 is a simplified sectional view of a heat accumulator for above-ground use according to a first embodiment of the invention,

5 is a simplified sectional view of a heat storage device for above-ground use according to a second embodiment of the invention,

6 is a simplified sectional view of a heat accumulator for above-ground use according to a third embodiment of the invention,

7 is a simplified sectional view of a heat accumulator for above-ground use according to a fourth embodiment of the invention, and Figures 8 to 10 examples of a three-layer wall structure for the inner container.

FIG. 1 shows, in a simplified sectional representation, a spherical heat accumulator 10 with a storage container 12, which comprises an inner container 14 and an outer container 16. The storage container 12 is arranged in this example in use in the ground. The inner container 14 is made by a blow molding process and is formed of a temperature resistant thermoplastic, preferably solid (i.e., non-foamed) polypropylene (PP). The inner container 14 can be filled with hot water as a storage medium 18, for example. The material of the inner container 14 is chosen so that a durability of the material against the operating temperature of the storage medium 18, in this case hot water, of up to 95 ° C is guaranteed. The capacity of the storage container 14 is in this embodiment, about 3000 1, which corresponds to a diameter of the spherical storage container 12 of about 2.10 to 2.20 m. The outer container 12 is also formed of plastic. The size and weight of the storage container 14 are thus well suited for load transport of the storage container 14, for example, for long-distance transport in a truck.

The outer container 16, which is also made in the B las molding process, consists of a pressure-resistant thermoplastic material, preferably solid polyethylene (PE) in order to achieve a sufficiently high resistance of the outer container 16 against the earth's external pressure of the soil. As a result, a particularly high stability of the storage container 12 is achieved. A gap 20 is formed between the inner container 14 and the outer container 16, which is filled with a heat-insulating, pressure-resistant rigid foam, preferably polyurethane (PU). The gap 20 is loaded by the pressure of existing in the irrigation tank 14 hot water 18. By filling the gap 20 with the heat-insulating, pressure-resistant rigid foam is achieved that the heat losses of the storage medium 18 are minimized in the inner container 14, while compressing the gap 20 by the internal pressure of the inner container 14, which is in the range of 100 to 200 kPa (about 10 to 20 m water column) is avoided.

The storage container 12 closes up pressure-resistant with a pressure cover 22 made of steel, wherein the pressure lid 22 for a possible inspection of the inner container 14 is removable. The heat accumulator 10 is coupled to an energy transport system (not shown here), wherein a tube 24 is provided in the storage container 12 for discharging the storage medium 18 and another tube 40 for supplying the storage medium 18. A mounting housing 26, which is formed for example from a plastic cylinder, is arranged in a neck region 28 of the storage container 12 and lies with its underside on the outer container 16. It can be welded to the outer container 16 there. This mounting housing 26, which includes an insulating ring 30, serves to protect the arranged in a mounting area for connections 32 (not shown here) fittings from rainwater and soil. The insulating ring 30 is made of insulating plastic material, such as polyurethane (PU), and protects against heat loss, which may occur in the region of the pressure cover 22, since there is a heat-conducting bridge. Figure 2 shows a detailed sectional view of the neck portion 28 of the storage container 12 of Figure 1. In this embodiment, a pipe is provided by guide 34 at the neck 36 of the storage container 12 for the supply and / or discharge of the storage medium 18. The tube 24 is fixedly connected to the inner wall of the inner container 14 in the region of the pipe duct 34 for better sealing by means of a weld 44. The pipe 24 is flanged in the region of the pipe duct 34 of the outer container 16 by means of a flange 46. A clamping ring 42 serves to lock the pressure cover 22. Above the pressure cover 22, a further lid 38 is arranged. This cover 38 is formed of a heat-insulating plastic and serves to heat insulation of the storage container 12 in the region of the pressure cover 22, which is formed of steel.

FIG. 3 shows, in a sectional view, three heat accumulators 10a, 10b, 10c, which differ in their different capacities of the respective inner container 14 and, in this exemplary embodiment, have a capacity of 2000, 3000 or 4000 l. The first heat storage 10a with the capacity of 2000 1 comprises a spherical inner container 14a ₅ which has a diameter of 1.60 m and a spherical outer container 16a, which has a diameter of 1.80 m. The second heat storage 10b has the capacity of 3000 l and comprises an inner container 14b with the diameter of 1.80 m and an outer container 16b with the diameter of 2.00 m. The third heat storage 10c with the capacity of 4000 liters comprises an inner container 14c with the diameter of 2.00 m and an outer container 16c with the diameter of 2.20 m. The respective inner container 14 and the respective outer container 16 of the spherical heat accumulator 10 are, as already mentioned, produced in the blow molding process.

The blow molding process is used to produce the respective inner container 14 or the outer container 16 made of plastic. In this blow molding process, plastic granulate, which forms the basis of the thermoplastic, is first melted in an extruder, and a hot plastic tube is passed through a nozzle into an open blow mold. Subsequently, the blow mold is closed and the enclosed plastic hose inflated with compressed air and pressed against the contours of the blow mold. Due to the cold surface of the blow mold, the plastic tube cools quickly, with the plastic has adapted to the shape of the blow mold and is firm. By varying the material thickness in the plastic tube, the thickness of the walls of the hollow body can be controlled. At the end of the cooling process, the hollow body can be removed from the blow mold.

The storage container 12 can be manufactured in a simple manner by the inner container 14 is made of thermoplastic material in a blow molding process as described above and is produced in a further blow molding process, the outer container 16 made of thermoplastic material, wherein the outer container 16 each have a larger diameter than the Inner container 14 has. Subsequently, the outer container 16 is divided into at least two parts and arranged the parts of the divided outer container 16 at a predetermined distance from the outer surface of the inner container 14, wherein the parts of the outer container 16 by means of a welding process interconnected with each other. are and the gap 20 between the inner container 14 and the outer container 16 is filled with plastic foam material.

When B las molding process are required to make the inner container or the outer container different blow molding. These blow molds are relatively expensive to produce and are expensive. Therefore, the blow molding method can be configured to use the same blow molds for the manufacture of a plurality of different volume storage tanks for the required inner tanks and the outer tanks. The small-sized storage container 10a shown in FIG. 3 has an outer container 16a made by means of a blow mold having an outer diameter of 1.80 m. The same blow mold can be used for the medium volume storage vessel 10b to fabricate the inner vessel 14b of a different plastic material. The blow mold for the outer container 16b may be used for the storage container 10c to manufacture the inner container 14c. In order to produce the three storage containers 10a, 10b, 10c shown in FIG. 3, six blow molds are therefore not required, but only four. The diameters of the outer container and inner container must be matched accordingly, so that the same blow mold can be used once for an outer container and once for an inner container. In an analogous manner, this can also be continued for a larger number of storage containers.

FIG. 4 shows a simplified sectional illustration of a heat store 50 for above-ground use according to a first embodiment of the invention. Elements with the same structure or the same function have the same reference numerals. The heat accumulator 50 is used primarily in heating systems in conjunction with thermal solar systems, heat pumps, solid fuel boilers, boilers and gas water heaters. The heat accumulator 50 is filled with a storage medium 18. The task of the heat accumulator 50 is to store the heat of the storage medium 18 over as long a period as possible.

As the certain for use in the soil heat storage 10 of Figures 1 to 3 and the above-ground heat storage 50 of Figure 4 comprises an in a B las molding produced inner container 14 and also in a B las molding produced outer container 16. The inner container 14 made of plastic, especially polypropylene. The outer container is made of a thermoplastic material, in particular polyethylene, polypropylene or a thermosetting plastic. The outer diameter of the inner container 14 is smaller than the inner diameter of the outer container 16. The intermediate space formed in this way between the inner container 14 and the outer container 16 is filled with a heat-insulating, pressure-resistant rigid foam, preferably hard polyurethane. The use of plastics ensures that the heat of the storage medium 18 can be stored for a long time. The thermal conductivity of plastics is significantly lower than the thermal conductivity of metallic materials, so that the heat losses are lower.

The outer container 16 has the largest dimension an outer diameter of at most 79 cm. In this way it is achieved that the heat storage 50 can be easily transported through standardized doors with a width of 80 cm, so that the heat storage 50 to simple Way, without having to be broken down into its individual parts, in homes, especially in cellars, can be built. The heat accumulator 50 has a capacity of about 400 1.

The bottom 15a of the inner container 14 is hemispherical in shape. Similarly, the bottom 15a opposite segment 15b, in which the opening portion of the inner container 14 is formed, formed hemispherical. The intermediate region 15c between the bottom 15a and the segment 15b is cylindrical. By this geometric configuration of the inner container 14, a high compressive strength is achieved. The outer container 16 has approximately the same shape as the inner container 14. The bottom 17 of the outer container 16 is not completely hemispherical in shape but flattened so that the heat accumulator 50 can safely stand upright on this flattened bottom in use.

Alternatively, both the inner container 14 and the outer container 16 may be formed completely spherical. In this way, a very high pressure resistance of the heat accumulator 50 is achieved.

The heat accumulator 50 has on the side opposite the bottom of a container opening which is pressure-tight with the aid of a pressure cap 58. The pressure cover 58 comprises a plurality of openings 60, 62 through which various components, in particular heat exchangers, temperature sensors, filling lines and / or discharge lines, can be introduced. Further, the opening of the heat accumulator 50 and the pressure lid 58 are covered by a pot-like insulating hood 64. The insulating hood 64 comprises an insulating disk and two interconnected semi-annular elements which enclose the insulating disk. The The insulating cover 64 serves, on the one hand, to protect the components introduced via the openings 60, 62 and to isolate the heat accumulator 50.

The outer container 16 includes a first part 52 and a second part 54 which are fixedly connected to each other via a welded joint 56. The welded connection 56 is preferably arranged in the cylindrical intermediate region of the outer container 16.

By the storage medium 18, an internal pressure is exerted on the heat accumulator 50. Due to the internal pressure of the heat accumulator 50 is claimed by a hoop stress. The internal pressure is to be absorbed in particular by the inner container 14, the outer container 16 and the hard foam insulation. From a creep internal pressure diagram for the plastics used, the maximum tolerable reference voltage can be determined for a desired service life and the corresponding operating temperature of the components. The components are to be dimensioned such that the circumferential stress caused by internal pressure is less than or equal to this determined reference voltage. If the actually occurring stress is greater than the reference stress, the desired service life at the operating temperature is not achieved. The higher the internal pressure, the greater the wall thickness of the respective component must be selected, so that the comparison voltage is not exceeded. The higher the temperature of the component, the lower the comparison voltage. The heat accumulator 50 is dimensioned such that a large part of the load caused by the internal pressure is absorbed by the outer container 16. The outer container 16 has a temperature substantially equal to the room temperature, that is about 2O ⁰ C corresponds. The mean temperature of the inner container 14, however, is due to the warm storage medium 18th significantly higher. The storage medium has a temperature of 95 ⁰ C, the average temperature of the inner container 14 is between 60 to 70 ⁰ C. The outer container 16 thus requires a much smaller wall thickness than the inner container 14 in order to withstand the same internal pressure. The sum of the wall thickness of the inner container 14 and the wall thickness of the outer container 16 of the heat accumulator 50 is substantially less than the summed wall thickness of an inner container and an outer container in a heat accumulator, in which the load caused by an internal pressure is substantially absorbed by the inner container. This saves up to 50% of the material. Furthermore, the heat accumulator 50 thereby becomes lighter, so that it is easier to handle and can be transported more cheaply. Likewise, the cooling time is significantly reduced in the blow molding process by the smaller wall thickness.

In the invention, for all examples, the wall thickness of the outer container 16 by a factor of 1.5 to 2.5 greater than the wall thickness of the inner container 14th

Advantageously, the inner container 14 and the rigid foam insulation are constructed such that they have long-term creep behavior, which are coordinated with one another in such a way that a minimum remaining running time is ensured. Further, it is advantageous that the outer container 16 has a strength which is sufficient after reaching this minimum remaining time to absorb the full load caused by the internal pressure.

FIG. 5 shows a simplified sectional view of a heat store 70 for above-ground use according to a second embodiment of the invention. Compared with the heat shown in FIG. Memory 50, the cylindrical intermediate portion of the heat accumulator 70 is longer, so that the heat accumulator 70 of Figure 5 has a larger capacity than the heat storage tank 50 of Figure 4 has. In use, the heat storage 70 is upright on the floor 16a.

The respective inner container 14 and outer container 16 of the heat storage 50, 70 of Figures 4 and 5 are, as already mentioned, produced in a blow molding process. The heat accumulator 50, 70 according to FIG. 4 or 5 can be produced in a simple manner with the method described in connection with the heat accumulator 10 intended for use in the soil in the description of FIG.

FIG. 6 shows a simplified sectional illustration of a heat accumulator 80 for above-ground use according to a third embodiment of the invention. The outer diameter of the inner container 14 is about 79 cm. The outer container 16 comprises two parts 52, 54. The two parts 52, 54 of the outer container 16 are dimensioned such that they each do not exceed a maximum dimension in a direction of 79 cm. In this way it is achieved that both the inner container 14 and the two parts 52, 54 of the outer container 16 can be easily transported individually through a standard door with a width of about 80 cm, thereby setting up the heat storage 80 in homes , especially in cellars, is easily possible.

The first part 52 of the outer container 16 and the second part 54 of the outer container 16 are connected to one another via a screw connection. For this purpose, one of the two parts 52, 54 has an internal thread 82 and the other part 52, 54 has an external thread 84 which is complementary to the internal thread 82. By screw connection, the two parts 52, 54 of the outer container 16 when installing the heat accumulator 80 are connected to one another at its destination in a simple manner. Likewise, the two parts 52, 54 in a disassembly in a simple manner can be separated from each other destructively. The coherent screw connection reduces heat losses.

Alternatively, the parts 52 and 54 may be connected together by a clamping ring.

FIG. 7 shows a simplified sectional view of a heat accumulator 90 for above-ground use according to a fourth embodiment of the invention. The heat storage 90 comprises an inner container 14 with a diameter of about 79 cm. The outer container 16 is divided into three parts 92, 94, 96. The three parts 92, 94, 96 are dimensioned such that they each do not exceed a length of 79 cm. The first part 92 is connected to the second part 94 via a first screw connection 98, and the second part 94 is connected to the third part 96 via a second screw connection 100. The screw 98, 100 are each formed by an internal thread and an external thread complementary to this internal thread.

Both the outer and the inner thread are formed in the blow molding process to the parts 92, 94, 96 with. Due to the multi-part design of the heat accumulator 90, a larger volume is achieved.

In alternative embodiments of the invention, the heat accumulator 90 can also consist of more than three parts, eg four parts, whereby a larger volume of the heat accumulator is achieved and / or the size of the components is reduced, so that the heat storage can be transported through smaller doors or other openings.

The storage containers 12 of the heat storage 80, 90 of Figures 6 and 7 can be prepared in a simple manner by means of a blow molding process. For this purpose, in a first blow molding process, as described in connection with Figure 3, the inner container 14 made of thermoplastic material. In further blow molding processes, the individual parts 52, 54, 92, 94, 96 of the outer container 16 are produced, wherein the respective inner and outer threads 82, 84 are formed directly with. In the next step, the hard foam insulation is attached to the individual parts 52, 54, 92, 94, 96. For this purpose, the parts 52, 54, 92, 94, 96 of the outer container 16 are filled with rigid foam material with the aid of foam molds, each of which has an inner core whose diameter corresponds to the outer diameter of the inner container 14. In this process, the parts 52, 54, 92, 94, 96 respectively form the outer mold and the inner cores of the foam molds the corresponding inner shape. The space between the parts 52, 54, 92, 94, 96, and the inner cores is respectively filled with the insulating foam, so that the insulation is formed. The hard foam insulation remains after removal of the inner cores to the parts 52, 54, 92, 94, 96 adhere. The inner container 14 and the parts 52, 54, 92, 94, 96 of the outer container are individually transported to the site of the heat accumulator 80, 90 and assembled at the site by the parts 52, 54, 92, 94, 96 via the inner container 14th be slipped and firmly connected to each other with the help of the internal and external threads 82, 84 formed screw. The heat accumulator 50, 70, 80, 90 described in FIGS. 4 to 7 is set upright for operation, ie its longitudinal axis is vertical. The outer parts 52, 54, 92, 94, 96 and the associated hard foam insulation thus have horizontal dividing lines, which brings considerable technical advantages. A vertical separation of the insulation and the outer parts leads to a relatively long separation line. Now, if a pressure force is exerted on the outer shell of the inner container 14 due to its internal pressure on the rigid foam insulation, so a gap increases along this parting line between the parts and it increases the output via this gap heat loss. In the present invention, in particular in a screwing of the parts, relatively short separation paths and a better tightness are achieved, so that the heat loss is reduced.

In the previous embodiments, the inner container 14 is a single layer of solid PE or PP. In order to improve the property of heat storage even further, the inner container 14 may have a three-layer wall structure. The examples of Figures 8, 9 and 10 show such embodiments for an inner container 14 having an inner layer 102, a middle layer 104 and an outer layer 106. Preferably, the inner layer 102 comprises solid PP or solid PE and the outer layer 106 comprises solid PP or solid PE. The middle layer 104 comprises foamed PP or foamed PE (FIG. 8).

A further development is shown by the example according to FIG. 9, in which the middle layer 104 consists of solid or foamed PP or PE and additionally contains a reinforcement 108 made of glass fiber 108. In this way, the pressure stability of the inner container 14 can be further improved. Optionally, to further increase the compressive strength also a outer glass fiber reinforcement 110 of the outer layer 106 may be provided with polyester resin or epoxy resin. Example 9 may be modified such that the inner layer 102 and the outer layer 106 are made of solid PE or PP and the middle layer 104 is made of foamed PE or PP. The outer layer 106 then comprises a glass fiber reinforcement 110. With such a structure, the foamed middle layer 104 results in an improvement of the thermal insulation and by the Glasfaserarmierung 110 an improvement in the compressive strength.

Of great importance in heating technology is oxygen diffusion. This should be below a limit to ensure a high corrosion resistance of the heating pipes. For this purpose, DIN 4726 is to be fulfilled. In the examples according to the invention, the ratio of container volume to the container surface is relatively large and the wall thickness of the inner container 14 is large, so that only an extremely low oxygen diffusion can occur. A further improvement can be achieved by an oxygen barrier layer in the inner container 14. In the example of FIG. 10, the middle layer 112 used is a barrier layer known as EVOH (ethylene-vinyl alcohol) or SELAR (product name). This layer 112 can also be combined with the middle layer 104 according to the examples of FIGS. 8 and 9. Alternatively or additionally, an external fluorination and / or an internal fluorination of the inner container 14 can be carried out. LIST OF REFERENCE NUMBERS

10, 10a, 10b, 10c, 50, 70, 80, 90 heat storage

12, 12a, 12b, 12c storage container

14, 14a, 14b, 14c inner container

16, 16a, 16b, 16c outer container

18 storage medium, hot water

20 space

22 pressure lid

24 outlet pipe

26 mounting housing

28 neck area

30 insulating ring

32 Mounting area for connections

34 pipe feedthrough

36 neck

38 end cover

40 inlet pipe

42 clamping ring

44 weld

46 flange

52, 54, 92, 94, 96 parts of the outer container

56 White link

58 pressure lid

60, 62 holes

64 insulating hood

82, 84 threads

98, 100 s Ehrub connection

102 inner layer 104 middle class

106 outer layer

108 glass fiber reinforcement

110 fiberglass reinforcement

1 12 barrier layer

Claims

claims

A heat storage device (10, 50, 70, 80, 90) comprising a large-volume storage container (12) for storing a storage medium (18), the storage container (12) comprising an inner container (14) and an outer container (16),

characterized in that the inner container (14) made of a temperature-resistant thermoplastic material and the outer container (16) is formed from a pressure-resistant thermoplastic material,

a heat-insulating material is arranged in a gap (20) between the inner container (14) and the outer container (16),

and that the wall thickness of the outer container (16) by a factor of 1.5 to 2.5 is greater than the wall thickness of the inner container (14).

2. heat storage (10, 50, 70, 80, 90) according to claim 1, characterized in that the inner container (14) has a wall thickness of 4 to 10 mm, preferably 6 to 8 mm.

3. heat storage (10, 50, 70, 80, 90) according to any one of the preceding claims, characterized in that the outer container (16) has a wall thickness of 8 to 20 mm, preferably from 10 to 15 mm.

4. heat accumulator (10, 50, 70, 80, 90) according to any one of the preceding claims, characterized in that the distance between the outer circumferential surface of the inner container and the inner circumferential surface of the outer container 50 to 100 mm, preferably 70 to 90 mm.

5. heat accumulator (10, 50, 70, 80, 90) according to any one of the preceding claims, characterized in that the outer diameter of the outer container in the range between 500 and 1000 mm, preferably between 750 and 800 mm.

6. heat storage (10, 50, 70, 80, 90) according to any one of the preceding claims, characterized in that the inner container (14) has a volume of 200 to 6000 1, preferably for use outside a building 2000 to 4000 1 and for the use within a building has 200 to 800 1.

7. Heat storage according to one of the preceding claims, characterized in that the inner container (14) has a three-layer structure, wherein the inner layer comprises solid PP or solid PE and the outer layer of solid PP or PE.

8. Heat storage according to claim 7, characterized in that the middle layer comprises PP foam or PE foam.

9. Heat storage according to claim 7, characterized in that the middle layer comprises PE or PP and in each case a glass fiber reinforcement.

10. Heat accumulator according to one of claims 7 to 9, characterized in that the outer layer of the inner container (14) additionally comprises a glass fiber reinforcement.

11. Heat storage according to one of claims 7 to 10, characterized in that to reduce the oxygen diffusion of the inner container (14) comprises an oxygen barrier layer and / or an outer fluorination and / or an inner fluorination.

12. heat accumulator (10, 50, 70, 80, 90) according to any one of the preceding claims, characterized in that the outer container (16) comprises at least a first part (52) and a separate second part (54).

13. Heat storage according to claim 12, characterized in that the length of each part (52, 54) in the longitudinal axis is smaller than the diameter of the part (52, 54).

14. heat storage (10, 50, 70, 80, 90) according to claim 12 or 13, characterized in that the parts (52, 54, 92, 94, 96) of the outer container (16) each have a maximum of 790 mm long.

15. heat storage (10, 50, 70, 80, 90) according to claim 12 to 14, characterized in that the first part (52) or the second part (54) of the outer container (16) comprises an external thread, the other part comprises internal thread complementary to the external thread and the first part (52) and the second part (56) can be connected to one another by means of the screw connection formed by the external thread and the internal thread.

16. heat accumulator (10, 50, 70, 80, 90) according to claim 12 to 14, daduch in that the first part (52) and the second part (54) are connectable by a clamping ring.

17. Method for producing a large-volume storage container (12) for storing heat energy, in which an inner container (14) made of thermoplastic material is produced in a blow-molding process,

in a further blow molding process, an outer container (16) with a larger diameter than the inner container (14) is produced from thermoplastic material,

the outer container (16) is divided into at least two parts in annular form (52, 54) and the parts of the outer container (16) are arranged at a predetermined distance from the outer surface of the inner container (14) with a gap (20) between them,

then the parts of the outer container (16) are interconnected,

and in which the intermediate space (20) between the inner container (14) and the outer container (16) is filled with plastic foam material.

18. The method according to claim 17, characterized in that the annular parts (52, 54) of the outer container (16) are connected to each other via at least one screw.

19. The method according to any one of claims 17 to 18, wherein a plurality of storage containers (10a, 10b, 10c) are made with different volumes, wherein for a storage container (10b) with a medium volume as a blow mold for the inner container (14b), the blow mold of the outer container (16a) of the reduced volume storage container (10a) is used.

20. The method of claim 19, wherein for the storage container (10b) with a medium volume as a blow mold for the outer container (12b), the blow mold for the inner container (14c) of the storage container (10c) is used with increased volume.

21. Method for producing a large-volume storage container (12) for storing heat energy,

in which an inner container (14) made of thermoplastic material is produced in a blow-molding process,

in a further blow molding process, at least two parts (52, 54, 92, 94, 96) of an outer container (16) having a larger diameter than the diameter of the inner container (14) are made of thermoplastic material,

on the inside of the parts (52, 54, 92, 94, 96) of the outer container (16), which in the assembled state faces the inner container, in each case a layer of plastic foam material is applied, which is dimensioned so that an intermediate region ( 20) between the inner container (14) and the outer container (16) is at least partially filled by this layer,

the parts (52, 54, 92, 94, 96) of the outer container (16) are arranged around the inner container (14), and

then the parts (52, 54, 92, 94, 96) of the outer container (16) are interconnected.

22. The method according to claim 21, characterized in that the parts (52, 54, 92, 94, 96) of the outer container (16) in each case via at least one external thread and at least one internal thread formed screw connection are interconnected and the internal thread and the external thread in the blow molding process for producing the parts (52, 54, 92, 94, 96) of the outer container (16) with the respective parts (52, 54, 92, 94, 96) are integrally formed.