UNDERGROUND BUFFER STORAGE DEVICE AND METHOD FOR BUFFER STORAGE IN A HEAT STORAGE MEDIUM

Abstract

A buffer storage device and method including an underground storage chamber filled with a brine as a heat storage medium, a primary circuit filled with a first heat transfer medium, and a secondary circuit filled with a second heat transfer medium. A first heat exchanger in the primary circuit, through which the first heat transfer medium flows, is set up so as to transfer excess heat fed into the primary circuit from the first heat transfer medium to the brine in the underground storage chamber. A second heat exchanger in the secondary circuit, through which the second heat transfer medium flows, is set up so as to transfer, as required, at least some of the excess heat stored in the brine in the underground storage chamber to the second heat transfer medium. The secondary circuit is coupled to at least one heat consumer load.

Claims

1. A buffer storage device, comprising: an underground storage chamber filled with a brine as a heat storage medium: a primary circuit filled with a first heat transfer medium; a secondary circuit filled with a second heat transfer medium; a first heat exchanger provided in the primary circuit and through which the first heat transfer medium flows, wherein the first exchanger is set up so as to transfer excess heat fed into the primary circuit from the first heat transfer medium to the brine in the underground storage chamber; and a second heat exchanger provided in the secondary circuit and through which the second heat transfer medium flows, wherein the second heat exchanger is set up so as to transfer, as required, at least some of the excess heat stored in the brine in the underground storage chamber to the second heat transfer medium; and wherein the secondary circuit is coupled to at least one heat consumer load.

2. The buffer storage device according to claim 1, wherein the underground storage chamber is a cavity in a water-impervious rock layer.

3. The buffer storage device according to claim 1, wherein the brine is an aqueous solution of salts with at least 14 g of dissolved substances per 1 litre of water.

4. The buffer storage device according to claim 1, wherein the brine contains sodium chloride in a dissolved form.

5. The buffer storage device according to claim 4, wherein the brine contains sodium chloride in a dissolved form, with a concentration of from 2% to 30% by weight.

6. The buffer storage device according to claim 1, wherein the brine contains potassium chloride in a dissolved form.

7. The buffer storage device according to claim 6, wherein the brine contains potassium chloride in a dissolved form with a concentration of from 2% to 30% by weight.

8. The buffer storage device according to claim 1, wherein the first heat transfer medium of the primary circuit is one of water, alcohol-water solution, salt-water solution, and thermal oil.

9. The buffer storage device according to claim 1, wherein the second heat transfer medium of the secondary circuit is one of water, alcohol-water solution, ammonia, carbon dioxide, hydrocarbons, and halogenated hydrocarbons.

10. A method for a buffer storage of excess heat in a heat storage medium, comprising steps of: feeding of excess heat to be stored into a primary circuit filled with a first heat transfer medium; transfer of the excess heat with a first heat exchanger arranged in the primary circuit, through which the first heat transfer medium flows, to an underground storage chamber filled with a brine as a heat storage medium; intermediate storage of the excess heat in the brine of the underground storage chamber; removal, as required, of at least some of the excess heat temporarily stored in the brine, by transfer of the excess heat from the brine to a second heat transfer medium, by means of a second heat exchanger arranged in a secondary circuit, and through which a second heat transfer medium flows; and discharge of the excess heat to at least one heat consumer load coupled to the secondary circuit.

11. The buffer storage method according to claim 10, wherein the primary circuit with the first heat exchanger and the secondary circuit with the second heat exchanger, are in each case coupled in a heat-conducting manner to the underground storage chamber and to the brine located therein.

12. The buffer storage method according to claim 10, wherein the underground storage chamber is arranged in a cavity in a water-impervious rock layer, and the first heat transfer medium in pipework of the primary circuit, and the second heat transfer medium in pipework of the secondary circuit, are in each case led from a ground surface to the storage chamber and back to the ground surface.

13. The buffer storage method according to claim 10, wherein an aqueous solution of salts with at least 14 g of dissolved substances per 1 litre of water is deployed as the brine.

14. The buffer storage method according to claim 10, wherein the brine contains sodium chloride and/or potassium chloride in a dissolved form.

15. The buffer storage method according to claim 14, wherein the brine contains sodium chloride and/or potassium chloride in a dissolved form, with a concentration of 2% to 30% by weight.

16. The buffer storage device according to claim 2, wherein the cavity is in a salt dome.

17. The buffer storage device according to claim 5, wherein the brine contains sodium chloride in a dissolved form, with a concentration of from 10% to 30% by weight.

18. The buffer storage device according to claim 7, wherein the brine contains potassium chloride in a dissolved form with a concentration of from 10% to 30% by weight.

19. The buffer storage method according to claim 12, wherein the underground storage chamber is arranged in a cavity in a salt dome.

20. The buffer storage method according to claim 15, wherein the brine contains sodium chloride and/or potassium chloride in a dissolved form with a concentration of from 10% to 30% by weight.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0057] FIG. 1 is a schematic cross sectional side view of a buffer storage device in accordance with the present disclosure.

DETAILED DESCRIPTION

[0058] In what follows the accompanying FIGURE is described in detail.

[0059] The FIGURE shows in a schematic cross-sectional side view a buffer storage device 1 in accordance with the invention, wherein here, within a rock layer 2, an underground cavity 3 is used as an underground storage chamber 3, as a storage container for a heat storage medium. A contour 4 of the underground storage chamber 3, that is to say, the underground cavity 3, forms the boundary between the cavity 3 and the surrounding rock 2. The storage chamber 3, or cavity 3, is filled with a brine 5 as a heat storage medium. The underground storage chamber 3 is located entirely below the ground surface 6. A primary circuit 10 and a secondary circuit 20 are only sketched in the FIGURE to the extent that the corresponding components of the two circuits 10, 20 are also arranged underground.

[0060] In the primary circuit 10, a hot first heat transfer medium 11, which was previously charged with excess heat, or waste heat, for example from an industrial operation, is pumped through pipework R1 of the primary circuit 10 in the direction of the arrow 11, by means of a pump P1, in the direction of the underground storage chamber 3. The industrial operation in which the excess heat there present was fed into the primary circuit 10, for example by means of a further heat exchanger, or heat transfer device, is not illustrated in the FIGURE. The apparatus and components required for feeding the excess heat into the first heat transfer medium 11 within the primary circuit 10, such as a further heat exchanger, are also not explicitly shown, but are adequately familiar to the person skilled in the art. The hot first heat transfer medium 11 is thus pumped within the pipework R1 to a heat exchanger W1 of the primary circuit 10, through which the first heat transfer medium flows. In the heat exchanger W1, the excess heat is transferred to the brine 5 as a heat storage medium in the underground storage chamber 3, that is to say, delivered to the latter, whereby the first heat transfer medium cools down and returns to the ground surface as a comparatively cold first heat transfer medium 12 in the primary circuit 10. As mentioned earlier, the primary circuit 10 and the secondary circuit 20 described below are in each case closed circuits, which for simplicity are shown exposed in the FIGURE in the region of the level of the ground surface 6. In actual fact, the cold first heat transfer medium 12, symbolised in the FIGURE by an arrow 12, and apparently emerging from the ground surface 6, and also the hot first heat transfer medium 11, symbolised by an arrow 11, continue to be located within the closed pipework R1 of the primary circuit 10. The cold first heat transfer medium 12 can in turn be charged with excess heat, or waste heat, for example from an industrial operation, in order to serve again as the hot first heat transfer medium 11 for purposes of heating the brine 5 in the storage chamber 3.

[0061] Advantageously, the storage chamber 3 is very well thermally insulated by virtue of the surrounding rock 2, which is why heat losses during buffer storage can be reduced.

[0062] A separate secondary circuit 20 contains a second heat transfer medium, which serves to remove, that is to say, deplete, the heat buffered in the storage chamber 3. In an analogous manner to the structure of the primary circuit 10, the secondary circuit 20 also comprises a pump P2, pipework R2 and a heat exchanger W2. The arrow 21 symbolises the cold second heat transfer medium 21, which is pumped in the direction of the arrow 21 in the secondary circuit 20 within the pipework R2 towards the underground storage chamber 3. Buffered excess heat is transferred in the heat exchanger W2 from the previously heated brine 5 inside the storage chamber 3 to the cold second heat transfer medium 21 that flows through the heat exchanger W2. Through appropriate heat transfer, at least some of the excess heat is transferred to the second heat transfer medium, which is thereby heated. The arrow 22 symbolises the heated, that is to say, hot, heat transfer medium 22, which then travels upwards within the secondary circuit 20 to the ground surface 6, and there—still located within the pipework R2—transfers the absorbed buffered heat to a heat consumer load coupled to the secondary circuit 20. The heat consumer load, for example a heating system of a building, as well as the apparatus and equipment required for heat removal, such as a further heat exchanger, are not illustrated in the FIGURE for the sake of simplicity. The second heat transfer medium is cooled down accordingly, and is again available within the closed secondary circuit 20 for the absorption of heat as a cooled, that is to say, cold, second heat transfer medium 21.

LIST OF REFERENCE SYMBOLS

[0063] 1 Buffer storage device

[0064] 2 Rock

[0065] 3 Underground storage chamber, cavity

[0066] 4 Contour of the underground storage chamber or cavity

[0067] 5 Brine

[0068] 6 Ground surface

[0069] 10 Primary circuit

[0070] 11 Hot heat transfer medium of the primary circuit (arrow)

[0071] 12 Cold heat transfer medium of the primary circuit (arrow)

[0072] P1 Pump in the primary circuit

[0073] R1 Pipework of the primary circuit

[0074] W1 Heat exchanger of the primary circuit

[0075] 20 Secondary circuit

[0076] 21 Cold heat transfer medium of the secondary circuit (arrow)

[0077] 22 Hot heat transfer medium of the secondary circuit (arrow)

[0078] P2 Pump in the secondary circuit

[0079] R2 Pipework of the secondary circuit

[0080] W2 Heat exchanger of the secondary circuit