DE102024200585A1 - Storage system with multiple circulation - Google Patents

Abstract

The invention relates to a storage system for storing thermal energy with a charging circuit which comprises, in direct or indirect sequence, an evaporator and a compressor and a charging heat exchanger coupled to a heat accumulator and a throttle. To increase efficiency, it is initially provided that the compression and heat transfer take place in several stages. This means that there is a multiple arrangement of compressor and charging heat exchanger with a downstream line section. According to the invention, to further increase efficiency, the charging circuit is provided in several stages with a connection between a respective separator and the associated line section, wherein the separator is arranged between a throttle of the downstream stage and a throttle associated with the stage.

Description

TECHNICAL FIELD

The invention relates to a storage system for storing thermal energy, wherein thermal energy is stored in a heat storage unit via a charging circuit. High efficiency is achieved through multiple circulation.

BACKGROUND

Especially when renewable energy is available, energy is available during periods when there is no demand for it. In contrast, periods in which the supply of renewable energy is insufficient to meet demand must be bridged. Various storage technologies are used to balance energy generation and demand.

One well-known option is to store excess heat and electricity as thermal energy in heat storage systems. This thermal energy can then be recovered at a later time.

In one known design, a charging circuit is formed with an evaporator, a compressor, the heat accumulator, and a throttle. In this case, waste heat from other processes or energy generated from renewable sources is advantageously fed to the evaporator. The compressor is also advantageously driven using energy generated from renewable sources.

If additional energy is required at a different time, the energy can be recovered from the heat storage by using it to evaporate and superheat water so that the steam can be used in a steam turbine, for example to drive a generator.

SUMMARY OF THE INVENTION

The object of the present invention is to optimize the storage and recovery of energy.

The object is achieved by an embodiment of the invention according to the teaching of claim 1. Advantageous embodiments are the subject of the subclaims.

First, a storage system is used to store thermal energy with a charging circuit, which comprises, in direct or indirect sequence, an evaporator and a compressor and a charging heat exchanger coupled to a heat storage unit and a throttle.

To increase efficiency, compression and heat transfer are initially planned to occur in multiple stages. This means that there will be multiple arrangements of compressors and charge heat exchangers with subsequent pipe sections.

According to the invention, in order to further increase efficiency, the charging circuit is provided in several stages with a connection between a respective separator and the associated line section, wherein the separator is arranged between a throttle of the subsequent stage and a throttle associated with the stage.

DESCRIPTION OF THE INVENTION

A storage system of this type is used to store thermal energy. It comprises a multi-stage charging circuit and, advantageously, a multi-stage discharging circuit.

The charging circuit comprises, in direct or indirect sequence, an evaporator, compressor, charging heat exchanger, and throttle. The charging heat exchanger is coupled to a heat accumulator for storing thermal energy.

To increase efficiency, compression and heat transfer are initially planned to occur in multiple stages. Therefore, the evaporator is followed by a first compressor and a first charge heat exchanger and a first line section, a second compressor and a second charge heat exchanger and a second line section, and a final compressor and a final charge heat exchanger. The final charge heat exchanger is directly or indirectly connected to the final throttle.

All charging heat exchangers are directly or indirectly coupled to the heat storage tank so that heat can be transferred from the heated steam into the storage medium.

According to the invention, to further increase efficiency, the charging circuit is supplemented by a second separator and a second throttle, and a first separator and a first throttle, in direct or indirect sequence between the last throttle and the evaporator. It is provided that the first separator is connected to the first line section, and the second separator is connected to the second line section.

The charging circuit operates in the charging state of the storage system. Water is first evaporated in the evaporator, and the steam is then compressed by the first compressor. The thermal energy contained in the steam is transferred proportionally to the heat storage system via the first charging heat exchanger. Steam from the first separator is then added.

In a subsequent stage, the process is repeated, with the steam being compressed by the second compressor and the thermal energy contained in the steam being transferred proportionally via the second charging heat exchanger to the heat storage tank (02). Steam from the second separator is again added.

In the final stage, the steam from the last compressor is compressed again, and the thermal energy contained in the steam is transferred proportionally to the heat storage tank via the last charging heat exchanger. The cooled steam from the last charging heat exchanger is passed through the last throttle.

To better utilize the remaining heat contained in the steam, a portion of the steam is separated by the second separator and directed to the second line section. The remaining water and, if applicable, any remaining steam are directed through the second throttle.

The process is repeated in the next stage, with steam being separated again in the first separator, which is then routed in the same way as the first section of the line. Finally, the remaining portion is passed through the first throttle.

Through multi-stage heat transfer and the multi-stage return of a portion of the steam, the thermal energy present in the circuit can be optimally utilized for heat transfer to the heat storage system. This achieves particularly high efficiency.

The efficiency of storable thermal energy can be further increased by adding one or more additional stages. The increased installation effort must be taken into account.

At least in this respect, it is advantageous if the charging circuit is further supplemented by a third compressor, a third charging heat exchanger, and a third line section, either directly or indirectly, between the second line section and the last compressor. It would also be obvious to couple the third charging heat exchanger to the heat storage unit.

If a third stage is present, it is obviously also advantageous to arrange a third separator and a third throttle in the charging circuit in direct or indirect sequence between the last throttle and the second separator, the third separator being connected to the third line section.

In order to enable greater flexibility in the process control and, in particular, to be able to better take into account different pressures and temperatures when starting up the charging circuit, it is advantageous if there is a connection from the second separator to the first line section.

In this regard, it is irrelevant whether the connections run directly from the second separator to the first line section and the second line section, or whether a common line is first divided via a branch into a feeder to the first line section and the second line section. It is also irrelevant whether the connection from the first separator and the second separator are connected separately to the first line section, or whether the connections from the first separator and the second separator are combined and then connected together to the first line section.

If a third separator is present, the above description also applies to an advantageous connection from the third separator to the second line section.

It is particularly advantageous if the respective separator is designed to separate the steam partially, so that only steam is discharged in the separated portion. Furthermore, the separator preferably effects the separation in such a way that only water remains in the non-separated portion.

Particularly preferably, control valves are arranged in the connections from the respective separators to the corresponding line sections.

It is particularly advantageous if the storage system is expanded to include a multi-stage discharge circuit.

The discharge circuit comprises, in direct or indirect sequence, a pump, a discharge heat exchanger, a steam turbine, and a condenser. The discharge heat exchanger is coupled with the heat storage to recover heat energy.

To increase efficiency, heat transfer and expansion are initially planned to occur in multiple stages. Therefore, the pump is indirectly followed by a final discharge heat exchanger, a final steam turbine, a second connecting section, a second discharge heat exchanger, a second steam turbine, a first connecting section, a first discharge heat exchanger, and a first steam turbine. The condenser is directly or indirectly connected to the first steam turbine.

All discharge heat exchangers are directly or indirectly coupled to the heat storage tank so that heat can be transferred from the heated heat storage tank to the steam.

To further increase efficiency, it is particularly preferred to insert a first separator in the first connecting section and a second separator in the second connecting section in the discharge circuit. Furthermore, a first flow heat exchanger and a second flow heat exchanger are installed in direct or indirect sequence between the pump and the last discharge heat exchanger.

The first separator is connected to the first flow heat exchanger, and the second separator is connected to the second flow heat exchanger. In each separator, the volume flow coming from the steam turbine is divided, with one portion being directed to the corresponding flow heat exchanger and the other portion to the downstream discharge heat exchanger.

The discharge circuit operates when the storage system is in the discharge state. Water is first pumped from the pump to the first flow heat exchanger, which is heated using thermal energy from the steam coming from the first separator. This process is repeated in the second flow heat exchanger. This process heats and/or evaporates the water.

Following the flow heat exchangers, the water-steam mixture is evaporated in the final discharge heat exchanger (if not already completely evaporated by the flow heat exchangers) and heated by transferring thermal energy from the heat storage tank. The heated steam then drives the final steam turbine.

To increase efficiency, the second separator is located in the directly or indirectly following second connecting section, which divides the volume flow. A portion is separated and directed to the second flow heat exchanger.

The unseparated portion is fed to the second discharge heat exchanger, where it is reheated using heat from the heat storage tank. The heated steam then drives the second steam turbine.

The process is repeated in the next stage. First, the volume flow is divided in the first separator, with one portion being discharged to the first supply heat exchanger and the other portion being forwarded to the first discharge heat exchanger. There, the steam is reheated so that the first steam turbine can be operated.

Finally, the water is cooled down in the condenser before the pump pumps it back into the discharge circuit.

Through multi-stage heat transfer and the multi-stage conversion of thermal energy into rotational energy by the steam turbines, the thermal energy stored in the heat storage system can be optimally utilized. This achieves particularly high efficiency.

The efficiency in terms of usable heat energy can be further increased by adding one or more additional stages. The increased installation effort must be taken into account.

At least in this respect, it is advantageous if the discharge circuit comprises, in direct or indirect succession between the last steam turbine and the second connecting section, a third connecting section, a third discharge heat exchanger, and a third steam turbine. Analogously, the third discharge heat exchanger is to be coupled to the heat storage unit.

If a third stage is present, it is obviously also advantageous to arrange a third separator in the third connecting section and a third flow heat exchanger downstream of the second flow heat exchanger in the charging circuit, wherein the third separator is connected analogously to the third flow heat exchanger.

In principle, it is also possible to operate the charging circuit and/or the discharging circuit with a medium other than water/steam. For example, although with a higher Effort - higher efficiency can be achieved using CO2 as a medium.

Other media, particularly those exhibiting a phase change between gaseous and liquid within a technically feasible range, can also be used. Accordingly, the use of alternative media instead of water/steam in the charging circuit and/or the discharging circuit is expressly considered to be encompassed by the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

• 1 schematically outlines an exemplary storage device with charging circuit.
• 2 schematically outlines an exemplary storage device with discharge circuit.

DESCRIPTION OF THE EMBODIMENTS

In the 1 A storage device 01 with a charging circuit 11 is shown schematically. The essential element of the storage device 01 is the heat accumulator 02. Arrows symbolize the flow direction in the circuits 11.

The charging circuit 11 comprises a first compressor 13.1 by means of which the steam in the charging circuit 11 is compressed and thus heated.

The first compressor 13.1 is followed by a first heat exchanger 12.1, which is coupled to the heat storage unit 02. In this regard, it is initially irrelevant whether the first heat exchanger 12.1 is located directly adjacent to or within the heat storage unit 02. It can also be arranged separately, and, for example, a flow of a storage medium from the heat storage unit 02 through the first heat exchanger 12.1 back into the heat storage unit 02 can be provided.

During operation of the charging circuit 11, heat energy is released via the first heat exchanger 12.1 to heat the heat storage tank 02.

The first heat exchanger 12.1 is connected via a first connecting section to a second compressor 13.2, which is followed by a second heat exchanger 12.2. The same applies here as for the first compressor 13.1 and the first heat exchanger 12.1.

Furthermore, in this embodiment, a third compressor 13.3 and a third heat exchanger 12.3 are sketched following the second connecting section 16.2.

In this embodiment, the third connecting section is followed by a final compressor 13.n and a final heat exchanger 12.n, which 12.n also transfers heat energy to the heat storage unit 02.

Subsequently, in the charging circuit 11, the design has a final throttle 15.n and an evaporator 14. Advantageously, regenerative heat energy is supplied to the evaporator 14.

To increase efficiency, additional connections are used. Between the last throttle 15.n and the evaporator 14, there are a third separator 17.3, a third throttle 15.3, a second separator 17.2, a second throttle 15.2, a first separator 17.1, and a first throttle 15.1.

In the respective separators 17.1, 17.2, and 17.3, at least a portion of steam is separated from the volume flow. Preferably, the steam is separated, which is discharged, and water, which is passed on.

For this purpose, each separator 17.1, 17.2, 17.3 and 17.4 is connected to an associated connecting section 16.1, 16.2 and 16.3.

In the 2 A storage device 01 with a discharge circuit 21 is shown schematically. The essential element of the storage device 01 is the heat accumulator 02. Arrows symbolize the flow direction in the circuits 21.

The discharge circuit 21 comprises a pump 25, by means of which water is pumped to a first flow heat exchanger 28.1, a second flow heat exchanger 28.2, and a third flow heat exchanger 28.3. The water then flows through the final discharge heat exchanger 22.n, where the water is completely evaporated and heated.

The heated steam is passed through a final steam turbine 23.n, then through a third connecting section 26.3 to a third discharge heat exchanger 22.3. A third separator 27.3 is located in the third connecting section 26.3, which separates a portion of the mass flow. The separated portion is passed to the third feed heat exchanger 28.3.

The process is repeated with the third discharge heat exchanger 22.3 and the subsequent third steam turbine 23.3. In the subsequent second connecting section 26.2, there is a second separator 27.2, which can also separate a portion of the mass flow and lead it to the second flow heat exchanger 28.2.

This is followed by the second discharge heat exchanger 22.2 and the second steam turbine 23.2 as well as the first connecting section 26.1 with the first separator 27.1.

After the first discharge heat exchanger 22.1 and the first steam turbine 23.1, the circuit closes and leads back via a condenser 24 to the pump 25.

Claims (10)

Storage system (01) for storing thermal energy with a charging circuit (11), which (11) comprises, in direct or indirect sequence, an evaporator (14) and a first compressor (13.1) and a first charging heat exchanger (12.1) and a first line section (16.1) and a second compressor (13.2) and a second charging heat exchanger (12.2) and a second line section (16.2) and a last compressor (13.n) and a last charging heat exchanger (12.n) and a last throttle (15.n), wherein the charging heat exchangers (12.1, 12.2, 12.3, 12.4) are coupled to a heat accumulator (02); characterized in that the charging circuit (11) further comprises, in direct or indirect succession between the last throttle (15.n) and the evaporator (14), a second separator (17.2) and a second throttle (15.2) and a first separator (17.1) and a first throttle (15.1), wherein the first separator (17.1) is connected to the first line section (16.1) and the second separator (17.2) is connected to the second line section (16.2). Storage facility (01) to Claim 1 , wherein the charging circuit (11) comprises, in direct or indirect succession between the second line section (16.2) and the last compressor (13.n), a third compressor (13.3) and a third charging heat exchanger (12.3) and a third line section (16.3); wherein the third charging heat exchanger (12.3) is coupled to the heat accumulator (03). Storage system according to Claim 2 , wherein the charging circuit (11) further comprises, in direct or indirect succession between the last throttle (15.n) and the second separator (17.2), a third separator (17.3) and a third throttle (15.3), wherein the third separator (17.2) is connected to the third line section (16.3). Storage facility (01) according to one of the Claims 1 until 3 , wherein the second separator (17.2) is connected to the first line section (16.1); and/or wherein the third separator (17.3) is connected to the second line section (16.2). Storage facility (01) according to one of the Claims 1 until 4 , wherein the respective separator is designed to divert the proportional steam to the corresponding line section. Storage facility (01) according to one of the Claims 1 until 5 , with a discharge circuit (21), which (21) comprises, in direct or indirect sequence, a pump (25) and a last discharge heat exchanger (22.n) and a last steam turbine (23.n) and a second connecting section (26.2) and a second discharge heat exchanger (22.2) and a second steam turbine (23.2) and a first connecting section (26.1) and a first discharge heat exchanger (22.1) and a first steam turbine (23.1) and a condenser (24), wherein the discharge heat exchangers (22.1, 22.2, 22.3, 22.4) are coupled to the heat accumulator (02); wherein the discharge circuit (21) comprises, in direct or indirect sequence between the pump (25) and the last discharge heat exchanger (22.n), a first flow heat exchanger (28.1) and a second flow heat exchanger (28.2), and in the second connecting section (26.2), a second separator (27.2) which (27.2) is connected to the second flow heat exchanger (28.2), and in the first connecting section (26.1), a first separator (27.1) which (27.1) is connected to the first flow heat exchanger (28.2). Storage facility (01) to Claim 6 , wherein the discharge circuit (21) comprises, in direct or indirect succession between the last steam turbine (23.n) and the second connecting section (26.2), a third connecting section (26.3) and a third discharge heat exchanger (22.3) and a third steam turbine (23.3); wherein the third discharge heat exchanger (22.3) is coupled to the heat accumulator (02). Storage system according to Claim 7 , wherein the discharge circuit (21) comprises, in direct or indirect succession between the second flow heat exchanger (28.2) and the last discharge heat exchanger (22.n), a third flow heat exchanger (28.3) and, in the third connecting section (26.3), a third separator (27.3), which (27.3) is connected to the third flow heat exchanger (28.3). Method for operating a storage system (01) according to one of the preceding claims, wherein - water is evaporated in the evaporator (14); - the steam is compressed by the first compressor (13.1): - the thermal energy contained in the steam is transferred proportionally via the first charging heat exchanger (12.1) into the heat storage tank (02); - steam coming from the first separator (17.1) is added: - the steam is compressed by the second compressor (13.2): - the thermal energy contained in the steam is transferred proportionally via the second charging heat exchanger (12.2) into the heat storage tank (02); - steam coming from the second separator (17.2) is added; - the steam is compressed by the last compressor (13.n): - the thermal energy contained in the steam is transferred proportionally via the last charging heat exchanger (12.n) into the heat storage tank (02); - the cooled steam is passed through the last throttle (15.n); - steam is partially separated in the second separator (17.2); - the separated steam is passed to the second line section (16.2); - the unseparated portion is passed through the second throttle (15.2); - steam is partially separated in the first separator (17.1); - the separated steam is passed to the first line section (16.1); - the unseparated portion is passed through the first throttle (15.1). A method for operating a storage system (01) according to one of the preceding claims, wherein: - water is pumped by the pump (25); - the water is heated and optionally evaporated in the first flow heat exchanger (28.1); - the water and/or steam is heated and optionally evaporated in the second flow heat exchanger (28.1); - evaporation and/or heating takes place in the last discharge heat exchanger (22.n) with transfer of thermal energy from the heat storage device (02); - the steam is passed through a last steam turbine (23.n); - steam is at least partially separated by the second separator (27.2); - the non-separated portion is heated in the second discharge heat exchanger (22.2); - the steam is passed through the second steam turbine (23.2); - steam is at least partially separated by the first separator (27.1); - the non-separated portion is heated in the first discharge heat exchanger (22.1); - the steam is passed through the first steam turbine (23.1); - cooling takes place in the condenser (24).