Storage system with process steam supply

Abstract

The invention relates to a storage system for storing thermal energy with a charging circuit comprising, in direct or indirect sequence, an evaporator and a compressor, a charging heat exchanger coupled to a heat storage device, and a throttle. Furthermore, a process steam line suitable for supplying external systems with process steam is required. The charging circuit further comprises, in direct or indirect sequence between the charging heat exchanger and the throttle, an extraction throttle and a separator. The separator is connected directly or indirectly to the process steam line via a process steam heat exchanger.

Description

TECHNICAL FIELD

[0001] The invention relates to a storage system for storing thermal energy and for providing process steam, wherein thermal energy is stored in a heat storage unit via a charging circuit and discharged as process steam. BACKGROUND

[0002] Especially when renewable energy is available, energy is temporarily available for periods without a corresponding demand. On the other hand, 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.

[0003] One well-known option is to store excess heat and electricity in the form of thermal energy in heat storage systems. This thermal energy can then be recovered at a later time.

[0004] 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.

[0005] If additional energy is needed 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.

[0006] Regardless of the storage and staggered use of the stored energy, some plants require an essentially continuous supply of process steam.

[0007] If sufficient renewable energy is available, the process steam can be generated directly without environmental pollution.

[0008] If no renewable energy is immediately available, the process steam is usually generated through combustion processes or with electricity.

[0009] A disadvantage of the known design is that the use of renewable energy is not sufficiently taken into account when generating process steam. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to enable a substantially continuous supply of process steam with the best possible use of regeneratively generated energy.

[0011] The object is achieved by an embodiment of the invention according to the teaching of claim 1. Advantageous embodiments are the subject of the dependent claims.

[0012] 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.

[0013] Furthermore, a process steam line is required which is suitable for supplying external systems with process steam.

[0014] According to the invention, the charging circuit further comprises, in direct or indirect sequence between the charging heat exchanger and the throttle, a discharge throttle and a separator, wherein the separator is connected directly or indirectly to the process steam line via a charging process steam heat exchanger. DESCRIPTION OF THE INVENTION

[0015] A storage system of this type is used to store thermal energy. It comprises a charging circuit and a discharging circuit.

[0016] The charging circuit comprises, in direct or indirect sequence, an evaporator, a compressor, a charging heat exchanger, and a throttle. The charging heat exchanger is coupled to a heat accumulator for storing thermal energy.

[0017] The charging circuit operates when the storage system is in a charging state. Water is first evaporated as it passes through the evaporator. The steam is then compressed by the evaporator and thus heated. As the steam flows through the charging heat exchanger, the thermal energy contained in the steam is partially removed and transferred to the heat storage tank. The cooled steam then passes through the throttle before flowing back to the evaporator.

[0018] Furthermore, a process steam line is provided, as is typical for the system. This process steam line is intended to supply external systems with process steam.

[0019] According to the invention, the charging circuit is expanded such that a bleeder throttle and a separator are arranged in direct or indirect sequence between the charging heat exchanger and the throttle. It is provided that at least a portion of the steam can be separated from the discharging circuit via the separator.

[0020] If the separated steam has the right properties, it can be used directly as process steam. For this purpose, the process steam line is connected directly to the separator.

[0021] Alternatively, the separated steam can be fed to a charging process steam heat exchanger connected to the process steam line. This results in an indirect transfer of heat from the charging circuit to the process steam.

[0022] It is advantageous to have a connection from the charging process steam heat exchanger back to the charging circuit in the section between the throttle and the evaporator.

[0023] According to the invention, the volume flow is separated before being returned to the evaporator. For this purpose, the cooled steam is first passed through a bleed throttle. This is followed by a separation into a volume flow containing water and a portion of steam, which is then passed on to the throttle provided by the respective type. On the other hand, the separator separates a portion of steam, which is then fed either directly into the process steam line as process steam or to a process steam heat exchanger for transferring the thermal energy to process steam.

[0024] The embodiment according to the invention allows process steam to be generated using renewably obtained energy at the same time as storing excess energy.

[0025] The design of the storage system is particularly advantageous if process steam can be made available without reduction during the standstill of the storage system, ie during periods in which neither the charging circuit nor the discharging circuit is in operation.

[0026] For this purpose, a standby heat exchanger is planned to be connected to the heat storage system. The standby heat exchanger can then transfer thermal energy from the heat storage system to the process steam while the storage system is shut down.

[0027] In a first particularly advantageous variant, the process steam can be passed directly through the standby heat exchanger.

[0028] Alternatively, it is also possible to transfer heat energy from the standby heat exchanger to a standby process steam heat exchanger, which in turn is flowed through by the process steam.

[0029] In any case, the design with the standby heat exchanger is particularly advantageous, as it allows process steam to be generated largely independently of the current availability of renewable energy.

[0030] To recover the energy stored in the heat storage system, a discharge circuit is advantageously used. A discharge circuit of this type comprises, in direct or indirect sequence, a pump and a discharge heat exchanger, a steam turbine, and a condenser. To recover the thermal energy, the discharge heat exchanger is coupled to the heat storage system.

[0031] Typically, the discharge circuit of the storage system is operated in a discharge state. Water is first pumped by a pump and fed to the discharge heat exchanger. There, thermal energy from the heat storage tank is transferred to the medium flowing in the discharge heat exchanger, thus evaporating and heating the water. The heated steam is then fed to the steam turbine. The steam turbine output is fed back to the pump via a condenser.

[0032] A further supply of process steam during the operation of the discharge circuit is made possible by proportionally diverting steam from the steam turbine between the inlet and the outlet.

[0033] If the separated steam has the right properties, it can be used directly as process steam. For this purpose, the process steam line is connected directly to the steam turbine.

[0034] Alternatively, it is also possible to feed the separated steam to a discharge process steam heat exchanger connected to the process steam line. This results in an indirect transfer of heat from the discharge circuit to the process steam.

[0035] Accordingly, it is particularly advantageous to separate a proportion of steam from the steam turbine and feed it to a process steam line as process steam or to a discharge process steam heat exchanger to transfer the thermal energy to process steam.

[0036] In principle, it is also possible to operate the charging circuit and / or the discharging circuit – provided the process steam line is indirectly connected – with a medium other than water / steam. For example, higher efficiency can be achieved using CO2 as the medium – albeit with greater effort.

[0037] 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 The Fig. 1 schematically outlines an exemplary storage device 01 with charging circuit 11 and discharging circuit 21 as well as a process steam line 31. The Fig. Figure 2 schematically outlines an alternative storage device 41, wherein an indirect transfer of the heat energy to the process steam takes place. DESCRIPTION OF THE EMBODIMENTS

[0038] In the Fig. Figure 1 schematically shows a storage device 01 with a charging circuit 11 and a discharging circuit 21. The essential element of the storage device is the heat accumulator 02. Arrows symbolize the flow direction in the two circuits 11, 21.

[0039] The charging circuit 11 comprises a charging heat exchanger 12, which is coupled to the heat storage tank 02. In this regard, it is initially irrelevant whether the charging heat exchanger 12 is located directly on or in the heat storage tank 02. It can also be spaced apart, and, for example, a flow of a storage medium from the heat storage tank 02 through the charging heat exchanger 12 back into the heat storage tank 02 can be provided.

[0040] During operation of the charging circuit 11, heat energy is released via the charging heat exchanger 12 to heat the heat storage tank 02.

[0041] The embodiment according to the invention has a bleed throttle 16 in the charging circuit 11. This is followed by a separator 17, through which, during operation of the charging circuit 11, a portion of the steam flowing through the separator 17 is discharged as process steam to a process steam line 31.

[0042] The separator 17 is followed by a throttle 15 and an evaporator 14. Advantageously, regenerative heat energy is supplied to the evaporator 14.

[0043] The steam generated by the evaporator 14 is then compressed by the compressor 13 and fed to the charging heat exchanger 12.

[0044] Furthermore, a discharge circuit 21 is present, which also has a discharge heat exchanger 22. This is coupled to the heat storage unit 02 in the same way as the charging heat exchanger 12.

[0045] During operation of the discharge circuit 21, heat is released from the heat storage 02 to the discharge heat exchanger 22, so that the supplied water evaporates and the steam is heated.

[0046] In the discharge circuit 21, a steam turbine 25 is connected to the charging heat exchanger 12, by means of which, for example, a generator can be driven.

[0047] In the discharge circuit 21 there follows a condenser 24 for recooling and condensing the steam, wherein preferably the heat dissipated in the condenser 24 is used.

[0048] A pump 23 is connected to the condenser 24, by means of which the water can be pumped back to the discharge heat exchanger 22.

[0049] In the example shown, it is further provided that steam is discharged from the steam turbine 25 as process steam to the process steam line 31.

[0050] In the Fig. 2 shows an alternative embodiment of a storage device 41 according to the invention. The charging circuit 11 and the discharging circuit 21 correspond to the embodiment of Fig. 1 and in this respect reference is made to previous explanations.

[0051] To transfer the thermal energy from the storage system 01 to the process steam, process steam heat exchangers 42, 43, 44 are now used to separate the media from the storage system 01 and the process steam line 31.

[0052] It is provided that a charging process steam heat exchanger 42 is connected to the separator 17. A return line from the charging process steam heat exchanger 42 leads back into the charging circuit 11 to the section between the throttle 15 and the evaporator 14.

[0053] Similarly, a discharge process steam heat exchanger 44 is provided to be connected to the steam turbine 25. A return line from the discharge process steam heat exchanger 44 leads back into the discharge circuit 21 to the section between the steam turbine 25 and the condenser 24.

[0054] Furthermore, it is provided that a standby process steam heat exchanger 43 is connected to the standby heat exchanger 32.

[0055] The existing process steam heat exchangers 42, 43, 44 are connected to the process steam line 31 so that, depending on the operating state of the storage system 31, a supply of process steam is always possible.

Claims

[1] 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 compressor (13) and a charging heat exchanger (12) and a throttle (15), wherein the charging heat exchanger (12) is coupled to a heat accumulator (02); and with a process steam line (31) which (31) is suitable for supplying external systems with process steam; characterized by , that the charging circuit (11) further comprises, in direct or indirect sequence between the charging heat exchanger (12) and the throttle (15), a discharge throttle (16) and a separator (17); wherein the separator (17) is connected directly or indirectly to the process steam line (31) via a charging process steam heat exchanger. [2] Storage system (01) according to claim 1, wherein a standby heat exchanger (32) is coupled to the heat storage unit (02); wherein the standby heat exchanger (32) is connected directly or indirectly via a standby process steam heat exchanger to the process steam line (31). [3] Storage facility (01) according to 1 or 2, with a discharge circuit (21) which (21) comprises in direct or indirect sequence a pump (23) and a discharge heat exchanger (22) and a steam turbine (25) and a condenser (24), wherein the discharge heat exchanger (22) is coupled to the heat accumulator (02); wherein the steam turbine (25) is connected directly or indirectly to the process steam line (31) via a discharge process steam heat exchanger. [4] Method for operating a storage system (01) according to one of the preceding claims, where in a charging state - water is evaporated in the evaporator (14); - the steam is compressed by the compressor (13); - the thermal energy contained in the steam is transferred proportionally via the charging heat exchanger (12) into the heat storage tank (02); - the cooled steam is passed through a bleeder throttle (16); - the remaining steam is at least partially separated by the separator (17), wherein the separated steam is fed to a process steam line (31) as process steam or to a charging process steam heat exchanger for transferring the thermal energy to process steam. [5] Method according to claim 4, wherein, when the storage system (01) is at a standstill, thermal energy from the heat storage (02) is transferred to process steam by the standby heat exchanger (32) directly or indirectly via a standby process steam heat exchanger. [6] Method according to claim 4 or 5, where in a discharge state - water is pumped by a pump (23); - thermal energy is transferred from the heat storage (02) in the discharge heat exchanger (22) and the water is evaporated; - the steam is fed to a steam turbine (25) and is fed proportionally from the steam turbine (25) to the condenser (24), wherein steam is separated proportionally from the steam turbine (25) and fed to a process steam line (31) as process steam or to a discharge process steam heat exchanger for transferring the thermal energy to process steam.

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