DEVICE FOR STORING A LIQUID

Abstract

The invention relates to an apparatus for storing a liquid, comprising at least two series-connected storage cells (3), with hot liquid being able to be supplied to, or removed from, a first storage cell (3) via a first central line (35) and with cold liquid being able to be supplied to, or removed from, a final storage cell of the series-connected storage cells (3) via a second central line (33), and with the temperature of the liquid in the series-connected storage cells (3) decreasing in each case from the first storage cell (3) to the final storage cell (3), and the individual storage cells (3) being connected to one another in each case via a connection (5; 7) from the lower region (11) of the warmer storage cell (3) to the upper region (15) of the colder storage cell (3), and with at least one storage cell (3) being closed by a cover (27) and therefore a gas space (25) being formed between the liquid in the storage cell (3) and the cover (27), wherein a gas line (29) branches off from at least one gas space (25) and enters into the liquid of a colder storage cell (3) or into the liquid in the connection (5; 7) of two adjacent storage cells (3), at least one of the adjacent storage cells (3) having a lower temperature than the temperature of the storage cell (3), from the gas space (25) of which the gas line (29) branches off.

Claims

1.-17. (canceled)

18. An apparatus for storing a liquid, comprising at least two series-connected storage cells (3), with hot liquid being able to be supplied to, or removed from, a first storage cell (3) via a first central line (35) and with cold liquid being able to be supplied to, or removed from, a final storage cell of the series-connected storage cells (3) via a second central line (33), and with the temperature of the liquid in the series-connected storage cells (3) decreasing in each case from the first storage cell (3) to the final storage cell (3), and the individual storage cells (3) being connected to one another in each case via a connection (5; 7) from the lower region (11) of the warmer storage cell (3) to the upper region (15) of the colder storage cell (3), and with at least one storage cell (3) being closed by a cover (27) and therefore a gas space (25) being formed between the liquid in the storage cell (3) and the cover (27), wherein a gas line (29) branches off from at least one gas space (25) and enters into the liquid of a colder storage cell (3) or into the liquid in the connection (5; 7) of two adjacent storage cells (3), at least one of the adjacent storage cells (3) having a lower temperature than the temperature of the storage cell (3), from the gas space (25) of which the gas line (29) branches off.

19. The apparatus according to claim 18, wherein the connection (5; 7) between two storage cells (3) comprises an intercellular space (7), the intercellular space (7) being separated from the colder storage cell (3) by pan overflow (23) and from the warmer storage cell (3) by a partition (17) with an opening (9) in the lower region (11), and therefore, during flow through the storage cells (3) from the hot first storage cell (3) to the cold final storage cell (3), the liquid flows in each case into the intercellular space (7) through the opening (9) in the lower region (11) of the partition (17) and out of the intercellular space (7) into the colder storage cell (3) via the overflow (23), or, in the event of flow in the opposite direction, flows into the intercellular space (7) via the overflow (23) and out of the intercellular space (7) into the warmer storage cell (3) through the opening (9) in the lower region (11) of the partition (17).

20. The apparatus according to claim 18, wherein a gas line (39) branches off from at least one gas space (25) of a storage cell (3) and enters into the liquid of a warmer storage cell (3).

21. The apparatus according to claim 18, wherein all of the storage cells (3) are closed by a cover (27), and a gas line (29) branches off at the cover (27) from all of the storage cells (3) apart from the coldest storage cell, said gas line leading into the adjacent colder storage cell (3) or into the connection (5; 7) of the storage cell (3) to the adjacent colder storage cell (3), and a gas outlet (31) branches off from the cover (27) of the coldest storage cell (3).

22. The apparatus according to claim 20, wherein all of the storage cells (3) are closed by a cover (27), and, from all of the storage cells (3) apart from the warmest storage cell, a gas line (39) branches off from the cover (27) and enters into the liquid of the adjacent warmer storage cell (3).

23. The apparatus according to claim 18, wherein a gas distributor (27) with which gas flowing through the gas line (29; 39) enters into the melt is formed at at least one end of the gas line (29; 39), which end has entered the liquid.

24. The apparatus according to claim 18, wherein the gas lines (29; 39) branching off from the cover (27) enter at least into the lower third of the liquid when the storage cell (3) is filled as far as the overflow (23).

25. The apparatus according to claim 18, wherein a compressor (38) with which the gas is transported into the liquid of the adjacent storage cell (3) or into the intercellular space (7) is accommodated in the gas line (29; 39).

26. The apparatus according to claim 18, wherein an apparatus for conveying the liquid is arranged in the connection (5; 7) between two adjacent storage cells (3).

27. The apparatus according to claim 26, wherein a level controller is installed in the storage cells (3), the level controller being designed in such a manner that, when a maximum level is reached, liquid is conveyed into an adjacent storage cell (3).

28. The apparatus according to claim 18, wherein each storage cell (3) is equipped with a heat exchanger (41), the heat exchangers (41) of adjacent storage cells (3) in each case being connected to one another and a heat transfer medium flowing through all of the heat exchangers (41) in series.

29. The apparatus according to claim 18, wherein the storage cells (3) are arranged helically around a center point.

30. The apparatus according to claim 29, wherein the first storage cell (3) is arranged in the center of the helically arranged storage cells (3) and the final storage cell (3) is arranged at the outer edge.

31. The apparatus according to claim 29, wherein a pressure-bearing wall (45) is constructed around the outermost storage cell of the helically arranged storage cells (3).

32. The apparatus according to claim 29, wherein a thermal insulating means (53) is accommodated between adjacent storage cells (3) in the helical arrangement that are not connected to one another via an intercellular space (7).

33. The apparatus according to claim 18, wherein each storage cell (3) has a thermal compensating profile (47).

34. The apparatus according to claim 33, wherein the thermal compensating profile (47) has at least one indentation protruding into the storage cell (3).

Description

[0046] Examples of the invention are illustrated in the figures and are explained in more detail in the description below.

[0047] In the figures:

[0048] FIG. 1 shows a plurality of series-connected storage cells, with a gas line branching off from the gas space of each storage cell and leading into the liquid of an adjacent storage cell,

[0049] FIG. 2 shows a storage cell, from the gas space of which a gas line branches off and leads into an intercellular space between two storage cells,

[0050] FIG. 3 shows a plurality of series-connected storage cells, with a gas line branching off from the gas space of each storage cell and leading into the liquid of an adjacent, colder storage cell and with a gas line branching off from said gas space and leading into the liquid of an adjacent, warmer storage cell,

[0051] FIG. 4 shows a plurality of series-connected storage cells, in each of which a heat exchanger is accommodated,

[0052] FIG. 5 shows a top view of a helical arrangement of the storage cells,

[0053] FIG. 6 shows a top view of a storage cell of a helical arrangement with thermal compensating profiles,

[0054] FIG. 7 shows a sectional illustration through two adjacent storage cells with a thermal compensating profile in the base.

[0055] FIG. 1 illustrates a plurality of series-connected storage cells, with a gas line branching off from the gas space of each storage cell and leading into the liquid of an adjacent storage cell.

[0056] An apparatus 1 for storing a liquid comprises a plurality of storage cells 3 which are in each case in the form of stratified accumulators, and therefore the liquid is warmer at the top and colder at the bottom in each storage cell 3 in accordance with the density thereof.

[0057] Two respectively adjacent storage cells 3 have a connection 5 which is designed in such a manner that the warmer, upper region of a colder storage cell 3 is connected to the lower, colder region of a warmer storage cell 3. By this means, the temperature of the warmer liquid in the colder storage cell 3 corresponds in each case to the temperature of the colder liquid in the warmer storage cell 3.

[0058] In the embodiment illustrated here, the connection 5 is designed in the form of an intercellular space 7. In order for liquid to be able to be transported via the intercellular space 7, the intercellular space 7 is connected via a lower opening 9 to the lower region 11 of the warmer storage cell 3 and via an upper opening 13 to the upper region 15 of the colder storage cell 3. The intercellular space 7 and the openings 9, 13 can be realized, for example, in such a manner that the intercellular space 7 is delimited from the warmer storage cell 3 by a first: wall 17 and from the colder storage cell 3 by a second wall 19. The first wall 17 here ends above the base 21 of the warmer storage cell 3 and of the intercellular space 7, and therefore the lower opening 9 is formed between the base 21 and the first wall 17. Alternatively, it is, of course, also possible to form a sufficiently large opening in the first wall 17. In contrast, the second wall 19 stands on the base between the intercellular space 7 and the colder storage cell 3, the second wall 19 ending at an overflow 23 below the maximum filling height of the colder storage cell 3, and therefore the liquid flows out of the colder storage cell into the intercellular space 7 via the overflow 23. However, as an alternative to the overflow 23, it is also possible to form an opening, through which the liquid can flow, at a corresponding position in the second wall 19.

[0059] In order to minimize a transfer of the heat of the liquid from the intercellular space 7 to the liquid in the storage cells 3, it is preferred if at least the second wall 19, but preferably the two walls 17, 19, is or are manufactured from a thermally insulating material or has or have a thermal insulating means.

[0060] A gas space 25 is located in each storage cell 3 above the liquid. According to the invention, the gas space 25, and therefore the storage cell 3, is closed by a cover 27. A gas line 29 branches off from the gas space 25. The gas line 29 here is guided in such a manner that said gas line leads into the liquid in a colder storage cell 3. So that positive pressure does not build up in the coldest storage cell 3, the coldest storage cell 3 is provided with a gas outlet 31 through which the gas can be removed. The gas removed from the gas outlet 31 can either be dispensed into the environment orin particular if the gas in the gas spaces 25 of the storage cells is an inert gas or has a composition with which regeneration of the liquid in the storage cells 3 is possiblecan be conducted into a gas accumulator.

[0061] The liquid stored in the apparatus can be used, for example, as a heat accumulator. This is advantageous particularly in solar power stations so that the latter can be operated not only in the event of solar irradiance, but also at times in which solar irradiance is not available.

[0062] In order to heat up the liquid, the latter is removed from the coldest storage cell 3 through a second central line 33, wherein the second central line 33 is arranged in the lower region of the coldest storage cell 3. The removed liquid absorbs heat in a solar array and the liquid heated in this manner is supplied to the warmest storage cell 3 via a first central line 35. The first central line 35 here is arranged in the upper region of the warmest storage cell. In order to equalize the liquid between the individual storage cells, liquid flows through the connections 5 between two storage cells from the warmest storage cell 3 in the direction of the coldest storage cell 3. The stored heat can be used at times at which solar irradiance is not available. For this purpose, the liquid is removed from the warmest storage cell 3 via the first central line 35, is supplied to a heat exchanger in which the heat is dispensed to a steam circuit, and the liquid cooled in this manner is then returned to the coldest storage cell 3 via the second central line. In this case, liquid between the individual storage cells 3 is then equalized by liquid flowing in each case from a colder storage cell 3 into the adjacent, warmer storage cell 3 via the connection 5 of the adjacent storage cells 3.

[0063] As an alternative to the connection 5, which is illustrated here, between two storage cells 3 in the form of an intercellular space 7, it is also possible, for example, to design the connection 5 in the form of a pipeline. In addition, it is possible to accommodate an apparatus for conveying the liquid, for example a pump, in the connection 5 between two storage cells 3. In the embodiment illustrated here with the intercellular space 7, the pump is preferably positioned in the lower opening 17. In this connection, use can either be made of one pump, the conveying direction of which can be reversed, or, alternatively, of two adjacent pumps with respectively opposed conveying directions. If the connection 5 is a pipeline, the pump can be positioned at any suitable location in the pipeline.

[0064] FIG. 2 shows a storage cell, from the gas space of which a gas line branches off and leads into an intercellular space between two storage cells.

[0065] As an alternative to the embodiment which is illustrated in FIG. 1 and in which the gas line 29 leads into the liquid in a colder storage cell 3, the gas line 29, according to the embodiment illustrated in FIG. 2, leads into the connection 5 between two adjacent storage cells 3. This has the advantage that the temperature stratification of the liquid in a storage cell 3 is not disturbed by gas flowing in.

[0066] In addition, in the embodiment illustrated in FIG. 2, the gas line 29 ends lower in the liquid. This has the further advantage that longer contact of the liquid with the gas can be realized.

[0067] This is desirable in particular if the liquid can be regenerated by the contact of the liquid with the gas.

[0068] For improved regeneration, good exchange between the gas and the liquid is necessary. This can be realized, for example, by the use of a suitable gas distributor 37 with which the gas is fed in the form of small froth bubbles into the liquid.

[0069] In order to be able to overcome the hydrodynamic pressure and to be able to feed the gas into the liquid, the gas line 29 additionally accommodates a compressor 38 with which the gas is sucked out of the gas space 25 and introduced into the liquid.

[0070] Of course, the entry depth of the gas line and the use of a gas distributor for producing fine gas bubbles can also be used in the arrangement illustrated in FIG. 1.

[0071] FIG. 3 illustrates a plurality of series-connected storage cells, with a gas line branching off from the gas space of each storage cell and leading into the liquid of an adjacent, colder storage cell and with a gas line branching off from said gas space and leading into the liquid of an adjacent, warmer storage cell.

[0072] The embodiment illustrated in FIG. 3 differs from that illustrated in FIG. 1 in that, in addition, a second gas line 39 branches off from each gas space and leads into the liquid of a warmer storage cell 3. This enables pressure to be equalized both in the direction of the colder storage cells 3 and in the direction of the warmer storage cells 3.

[0073] In the embodiment illustrated in FIG. 4, a heat exchanger is accommodated in each of a plurality of series-connected storage cells.

[0074] A respective heat exchanger 41 can additionally be accommodated in the storage cells 3. In the embodiment illustrated here, each storage cell 3 is equipped with a heal: exchanger 41. The heat exchangers 41 here are connected in series, and therefore the heat transfer medium flows through all of the heat exchangers 41 in the series. The heat exchangers can firstly provide additional safety by being able to be usedin particular when the apparatus is used in solar power stationsin order, after a prolonged shut down, again to preheat salt which is stored in the apparatus and, secondly, the liquid stored in the apparatus can also be used directly as a heat carrier in order to heat the heat transfer medium flowing through the heat exchangers 41. In this connection, it is also possible, for example, for the heat exchangers 41 to be used as steam generators and for the heat transfer medium flowing through the heat exchangers 41 to be water which is first of all heated, then evaporated and superheated. The heat transfer medium here can flow through the heat exchangers 41 either in the direction from the coldest storage cell 3 to the warmest storage cell 3 or in the opposite direction from the warmest storage cell 3 to the coldest storage cell 3.

[0075] In order to be able to arrange the series-configured storage cells 3 as compactly as possible and in order, in addition, to be able to save on insulating material and construction material, it is preferred to arrange the storage cells 3 helically. Such a helical arrangement of the storage cells is illustrated in a top view in FIG. 5.

[0076] It is particularly preferred if, in the helical arrangement, the hottest storage cell 3 is arranged in the center and the coldest storage cells 3 arranged at the edge. By this means, the entire apparatus needs to be insulated from the environment only in respect of the colder liquid. By means of the helical arrangement, the intercellular walls 43 can be configured, as described above, to have less stability since adjacent cells stabilize one another by means of the liquid contained therein. Only the outermost storage cells 3 have to be supported by a pressure-bearing wall 45 which surrounds the entire helical arrangement.

[0077] In order to compensate for changes in geometry occurring due to temperature fluctuations, it is advantageous if the storage cells are equipped with thermal compensating profiles 47. A top view of a storage cell 3 of a helical arrangement with thermal compensating profiles 47 is illustrated in FIG. 6. The thermal compensating profile can be designed here, for example as illustrated here, in the form of an indentation running from the top downward in the wall of the storage cell 3.

[0078] FIG. 7 illustrates a sectional illustration through two adjacent storage cells with a thermal compensating profile in the base.

[0079] So that no heat is dispensed to the base from the arrangement, the storage cells 3, as illustrated in FIG. 7, have an insulating means 51 preferably at the base 49. The base 49 of the storage cell 3, which base rests on the insulating means 51, can additionally be configured with a thermal compensating profile 47 to compensate for thermally induced changes in length.

[0080] So that no heat is dispensed from one storage cell to adjoining storage cell, it is furthermore advantageous if a wall insulating means 53 is formed between two storage cells. In addition, the wall insulating means 53 is preferably pressure resistant so that pressure forces acting on the walls of the storage cells 3 can be compensated for by the pressure forces acting on the wall of the adjacent storage cell 3.

LIST OF REFERENCE NUMBERS

[0081] 1 Apparatus for storing liquid [0082] 3 Storage cell [0083] 5 Connection of two storage cells 3 [0084] 7 Intercellular space [0085] 9 Lower opening [0086] 11 Lower region [0087] 13 Upper opening [0088] 15 Upper region [0089] 17 First wall [0090] 19 Second wall [0091] 21 Base [0092] 23 Overflow [0093] 25 Gas space [0094] 27 Cover [0095] 29 Gas line [0096] 31 Gas outlet [0097] 33 Second central line [0098] 35 First central line [0099] 37 Gas distributor [0100] 38 Compressor [0101] 39 Second gas line [0102] 41 Heat exchanger [0103] 43 Intercellular walls [0104] 45 Pressure-bearing wall [0105] 47 Thermal compensating profile [0106] 49 Base [0107] 51 Insulating means [0108] 53 Wall insulating means