DE102018008011A1 - Energy storage with cryogenic fluids - Google Patents

Abstract

The invention relates to a device (1) for storing and storing electrical energy, comprising a system for liquefying air gases (2), a tank (3) for liquefied air gases, and a tank (3) via a first line (4). connected pump (5), a first heat exchanger (7) connected to the pump (5) via a second line (6) and a second heat exchanger (8) downstream of the first heat exchanger (7), and a second heat exchanger (8) downstream of the second heat exchanger (8) first turbine (9) with a first generator (10), a third line (11) connecting to the outlet of the first turbine (9) and opening into the first heat exchanger (7), the third line (11) downstream of the first A third heat exchanger (12) is connected to the heat exchanger (7), a first valve (13) being connected downstream of the third heat exchanger (12) in the third line (11), the third line being downstream of the first Valve opens into the tank (3) for liquefied air gases and a fourth line (14) leads from the tank (3) for liquefied air gases to the third heat exchanger (12), with a second valve in the fourth line downstream of the third heat exchanger (12) (15) is switched and the fourth line (14) leads to the atmosphere. The invention further relates to a method for storing and storing electrical energy.

Description

The invention relates to a device for storing and storing electrical energy, and to a corresponding method.

Since the share of renewable energy generation such as wind energy, photovoltaics etc. is increasing more and more, the electrical power that is fed into the power grid and cannot be regulated thereby has to be adjusted either with the help of conventional power plants or through energy storage in accordance with the current needs of consumers.

From the point of view of sustainability and economy, it is desirable to use an energy storage device that is quickly available, has a high capacity and a large output range, does not pollute the environment with toxic substances, is independent of geographical conditions and, if possible, has a long service life and a long one Offers efficiency with low investment costs.

One way to meet the above criteria is to store energy in the form of liquid air (LAES = Liquid Air Energy Storage). Here, excess electrical power is used to liquefy air and store it in tanks. If electrical power is to be delivered, the liquid air is removed from the tank, pumped to a higher pressure, evaporated and warmed with the aid of ambient heat or other heat sources, and, as a rule, expanded in a turbine in several stages with intermediate heating with power output. The air leaves the system almost without pressure.

In order to increase the efficiency, the compression waste heat resulting from the air liquefaction can be stored in heat stores in order to raise the turbine inlet temperature. Cold storage can also be used for the evaporation and heating of the air to minimize energy consumption during the liquefaction cycle. The heat and cold storage can consist, for example, of a bed of rock.

Furthermore, further LAES processes were developed, which other processes such as incorporate LNG (liquefied natural gas) regasification or waste heat from industrial plants in order to either minimize the energy required for air liquefaction or to increase the power output.

Other LAES processes use the air turbine to relax the compressed air to a pressure level that is suitable for entry into the combustion chamber of a gas turbine and thus integrate a gas turbine process into the LAES process. The hot exhaust gas from the gas turbine is used to increase the inlet temperature into the air turbine and thus the efficiency.

For the regasification of cryogenic fluids such as The supercritical regasification process was designed for LNG, which recirculates a partial flow of the total flow exiting the turbine via a heat exchanger for recuperation, and combines the cooled and liquefied partial flow exiting the heat exchanger with the high pressure flow leading to the turbine using a recirculation pump.

The object of the invention is to provide a device and a method for storing and storing electrical energy with a high degree of efficiency, which are at the same time inexpensive, require only a few components and offer high availability.

The invention achieves the object aimed at a device by providing that in such a device for storing and storing electrical energy, comprising a system for liquefying air gases, a tank for liquefied air gases, a tank connected to the tank via a first line Pump, a first heat exchanger connected to the pump via a second line and a second heat exchanger downstream of the first heat exchanger, and a first turbine downstream of the second heat exchanger with a first generator, a third line connects to the outlet of the first turbine and opens into the first heat exchanger , a third heat exchanger being connected in the third line downstream of the first heat exchanger, a first valve being connected downstream of the third heat exchanger in the third line, the third line being downstream of the first valve in the tank f r liquefied air gases opens and wherein a fourth conduit leading from the tank for liquefied air gases to the third heat exchanger wherein in the fourth line downstream of the third heat exchanger, a second valve is connected and wherein the fourth line leading to the atmosphere.

The basic idea of the invention is to recover (recuperate) the cold potential of the liquefied air gas, which is a cryogenic fluid, as much as possible by relaxing the fluid warmed up by ambient heat, low-value waste heat or stored heat to a lower but supercritical pressure in the first turbine and thus the degree of cruelty at the cold end of the first heat exchanger is minimized, which leads to a low outgassing fraction after the pressure has been reduced to the tank pressure level. The gas is degassed in the third heat exchanger Part used to lower the temperature of the fluid even further before the pressure was reduced, thus reducing the proportion of outgassing again. The lower the outgassed fraction, the higher the storage capacity of the device for storing and releasing energy or the lower the power consumption during the liquefaction process of the air gases in order to fill up the tank for liquid air gases. Thus, the invention ensures that the cold potential is recovered in the form of liquid air gases during the delivery of electrical power instead of filling up cold stores during the delivery of electrical power, as in the known LAES methods, which can then only be used during the liquefaction cycle in order to achieve the To reduce liquefaction work. As a result, the device for storing and storing energy with a similar degree of efficiency is significantly more cost-effective since the cold stores are eliminated. The overall system becomes simpler and clearer. In contrast to the supercritical regasification process described above, according to the invention, no partial stream is recirculated via a recirculation pump, but rather the entire fluid stream that emerges from the first turbine is cooled and liquefied and returned to the tank.

In an advantageous embodiment of the invention, a fourth heat exchanger is connected downstream of the pump, a fifth heat exchanger being connected in the second line between the fourth heat exchanger and the first heat exchanger, a fifth line branching upstream of the first heat exchanger from the third line, which line downstream of the first heat exchanger opens into the third line, a third valve being connected in the fifth line and a fourth valve being connected downstream of the branch of the fifth line from the third line and upstream of the confluence of the fifth line and the third line, so that on the high-pressure side or on the side of the lower, supercritical pressure, a fifth heat exchanger can be connected between the first and fourth heat exchangers, via which heat can be absorbed from the environment or released to the environment ann, wherein the fourth line downstream of the third heat exchanger opens into the fourth heat exchanger and wherein the second valve is connected downstream of the fourth heat exchanger in the fourth line. The fifth heat exchanger can reduce temperature fluctuations and thus thermal stresses within the first and fourth heat exchangers during starting or shutting down or during load ramps. There is also the possibility of raising the inlet temperature into the first turbine solely by entering ambient heat into the fifth heat exchanger if it is not possible to store stored waste heat or low-quality waste heat in the second heat exchanger, with the flow being the only entry of ambient heat on the side of lower, supercritical pressure with the help of the fifth line around the first heat exchanger. The fact that the fourth line opens into the fourth heat exchanger after it emerges from the third heat exchanger means that the outgassing fraction is further reduced and the efficiency is increased.

In an alternative advantageous embodiment, the third heat exchanger and the fourth heat exchanger are integrated in one component.

In a further advantageous embodiment, the third line opens into a degassing container, at the bottom of which a sixth line connects, which opens into the tank for liquefied air gases, a fifth valve being connected in the sixth line and the fourth line connecting in the gas space of the degassing container . Because the outgassing takes place in a separate container, costs for securing the tank for liquid air gases can be reduced.

In a further advantageous embodiment, a seventh line branches off upstream of the first valve from the third line, which ends in a second turbine which is coupled to a second generator, an eighth line connecting to the outlet of the second turbine and downstream of the first valve the third line opens. By relaxing the cryogenic fluid from a lower, supercritical pressure to a lower, subcritical pressure in the second turbine instead of in the second valve, the outgassing fraction can be further reduced and additional electrical power can be generated.

In a further advantageous embodiment, a non-return valve is connected in the second line downstream of the pump, a ninth line branching off from the second line downstream of the non-return valve and opening into a pressure tank, a tenth line connecting to the pressure tank, which line upstream of the first heat exchanger into the second line opens, a sixth valve being connected in the ninth line, a seventh valve being connected in the tenth line, the pressure tank being connected to an air-heated pressure build-up evaporator and an eighth valve being connected in the liquid-carrying line of the pressure build-up evaporator. The pressure tank can be designed for subcritical pressure and is used to temporarily provide a pressure drop for the first turbine even without a pump, which in connection with Heat input from the environment causes the black start ability.

In a preferred embodiment of the invention, the tank for liquefied air gases contains nitrogen. However, liquid air, liquid oxygen or liquid argon are also possible fluids.

In a further advantageous embodiment, an eleventh line branches off from the third line downstream of the first turbine and leads to a third turbine coupled to a third generator, a sixth heat exchanger being connected to the eleventh line and a twelfth at the outlet of the third turbine Lead to the atmosphere. With the help of the partial flow branched off from the total flow via the twelfth line, the increase in the oxygen concentration in the tank can be limited if air is used as the cryogenic fluid. In addition, the straightness at the cold end of the first heat exchanger can be reduced so that the outgassing fraction is reduced in the first valve after the cryogenic fluid has expanded. Ambient heat, stored heat or low-value waste heat can be entered via the sixth heat exchanger in order to raise the entry temperature into the third turbine. Alternatively, a multi-stage relaxation with intermediate heating is also possible.

The object directed to a method is therefore achieved by a method for storing and withdrawing electrical energy, in which air gases are liquefied and stored in a tank for storing electrical energy, and in which the stored liquid air gas is withdrawn via a second line through a first and a second heat exchanger is pumped to a first turbine, the air gas being heated in the first and second heat exchangers and expanded in the first turbine to drive a first generator, the air gas emerging from the first turbine first being the first heat exchanger and then the third heat exchanger is supplied, the cooled and liquefied from the third heat exchanger liquefied air gas via a first valve to the pressure prevailing in the tank for liquefied air gases and then passed into the tank for liquefied air gases, the outgassed cryogenic portion of the air gas is supplied to the third heat exchanger and emerges partially heated from this third heat exchanger, and the outgassed portion of the air gas is blown off into the atmosphere via a second valve.

It is advantageous if the liquefied air gas removed from the tank by means of a pump is brought to a pressure of over 170 bara.

The fluid is expediently removed from a tank. For smaller tank volumes, the tank can be designed as a pressure tank, which reduces the pump output and thus increases the efficiency. Large flat-bottom tanks with only a slight overpressure of 50-80 mbar are suitable for realizing larger storage capacities.

It is advantageous if the air gas is heated to the highest possible temperature before entering the first turbine. This can be caused by ambient heat or by stored heat, e.g. through stored compression waste heat from the liquefaction process for air gases, stored heat from an electrothermal energy storage (ETES = Electric Thermal Energy Storage), or with low-quality waste heat, e.g. the waste heat from a main air compressor of an air separation plant is produced.

If an electrothermal energy store is used, it is advantageous if the inlet temperature into the first turbine transmits above 500 ° C.

It is also advantageous if the lower supercritical pressure when using nitrogen is above 50 bara. As already mentioned above, the advantages of supercritical expansion are that a high proportion of the cold potential can be recovered by minimizing the degree of predilection at the cold end of the first heat exchanger, since the fluid mass flow, which is at a lower but supercritical pressure level, does not change phases goes through.

It is also advantageous if the portion of the expanded fluid mass flow which has been outgassed after the expansion from lower, supercritical pressure to the tank pressure level of the fluid mass flow emerging from the first heat exchanger cools the fluid mass flow to be expanded as much as possible, so that the outgassing portion is as low as possible. is in particular less than one seventh of the total mass flow. The outgassing fraction represents the loss of working capacity of the energy store during the withdrawal phase, and thus minimizing this loss is desirable in order to minimize the energy expenditure for the injection phase.

Since mixtures of liquefied air gases, e.g. Air, when degassing after a pressure reduction changes the concentration in the liquid phase and the proportion of higher-boiling components increases, it is advantageous to use pure air gases such as e.g. To use nitrogen.

It is also advantageous if an air separation plant with a large liquefaction capacity is used as the plant for the liquefaction of air gases.

• - Kostengünstige und effiziente Lösung für die Energiespeicherung,
• - Kostengünstige und effiziente Lösung für die Lastflexibilisierung von Luftzerlegungsanlagen,
• - Kostensparend auf Grund der Verwendung nur eines Pumpentyps,
• - Kostensparend auf Grund der Verwendung nur einer Turbinenstufe, die z.B. als Radialturbine ausgeführt werden kann,
• - Kostensparend, da keine Zwischenaufwärmung zwischen mehreren Turbinenstufen notwendig ist, wodurch nur eine geringere Anzahl von Wärmeübertragern benötigt wird,
• - Verflüssigung und Abgabe elektrischer Leistung können entkoppelt werden, wodurch Kosten und Komplexität verringert werden und die Flexibilität erhöht wird,
• - Schnelle Startfähigkeit, da im Gegensatz zu Wasser-Dampf-Kreisläufen nicht auf Dampfreinheit für die Dampfturbine gewartet werden muss,
• - Schnelle Lastrampen,
• - Schwarzstartfähigkeit kann problemlos integriert werden,
• - Primärfrequenzregelfähigkeit,
• - Auch bei längeren Anlagenstillständen treten keine Korrosionsprobleme auf,
• - Keine Notwendigkeit für chemische Konditionierung des Arbeitsmediums wie z.B. bei Wasser-Dampf-Kreisläufen,
• - Einfache Regelung,
• - Hohe Verfügbarkeit durch die Möglichkeit, alternativ Umgebungswärme zu verwenden,
• - Weiter Lastbereich und hoher Teillastwirkungsgrad, da Radialturbinen mit Düsenringverstellung verwendet werden können.

The supercritical recuperation process described here is a simple and stable process with which the cold potential of cryogenic fluids can be used efficiently to generate electrical power. The combination with a liquefaction process for air gases and the use of low-quality waste heat or stored heat offers the following advantages:

• - Inexpensive and efficient solution for energy storage,
• - Inexpensive and efficient solution for the load flexibility of air separation plants,
• - Cost-saving due to the use of only one pump type,
• - Cost-saving due to the use of only one turbine stage, which can be designed as a radial turbine, for example,
• - Cost-saving, since no intermediate heating between several turbine stages is necessary, which means that only a smaller number of heat exchangers is required,
• - Liquefaction and delivery of electrical power can be decoupled, which reduces costs and complexity and increases flexibility,
• - Fast start-up since, unlike water-steam cycles, there is no need to wait for steam to be cleaned for the steam turbine,
• - fast load ramps,
• - Black start capability can be easily integrated,
• - primary frequency controllability,
• - Even with long plant downtimes there are no corrosion problems,
• - No need for chemical conditioning of the working medium, such as in water-steam cycles,
• - simple regulation,
• - High availability due to the possibility of alternatively using ambient heat,
• - Wide load range and high partial load efficiency, as radial turbines with nozzle ring adjustment can be used.

• 1 Eine Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie nach der Erfindung,
• 2 Eine Variante der Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie zur Reduzierung der thermischen Spannungen in den Wärmeübertragern,
• 3 Eine Variante der Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie mit Ausgasung des auf unterkritischen Druck entspannten Fluids in einem Ausgasungsbehälter,
• 4 Eine Variante der Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie mit Entspannung des überkritischen Fluids niedrigeren Drucks in einer Flüssigturbine,
• 5 Eine Variante der Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie mit einem Drucktank für die Bereitstellung von Schwarzstartfähigkeit.
• 6 Eine Variante der Vorrichtung zur Ein- und Ausspeicherung elektrischer Energie mit einer Abzweigung eines Teilstroms im nichtkryogenen Bereich.

The invention is explained in more detail by way of example with reference to the drawings. They show schematically and not to scale:

• 1 A device for storing and storing electrical energy according to the invention,
• 2nd A variant of the device for storing and storing electrical energy to reduce the thermal stresses in the heat exchangers,
• 3rd A variant of the device for the storage and storage of electrical energy with outgassing of the expanded fluid to subcritical pressure in a outgassing container,
• 4th A variant of the device for storing and withdrawing electrical energy with relaxation of the supercritical fluid at lower pressure in a liquid turbine,
• 5 A variant of the device for storing and storing electrical energy with a pressure tank for the provision of black start capability.
• 6 A variant of the device for storing and storing electrical energy with a branch of a partial flow in the non-cryogenic area.

The 1 shows schematically and by way of example a device 1 for storing and storing electrical energy, comprising a system for liquefying air gases 2nd and a tank 3rd for liquefied air gases. The device further comprises a via a first line 4th with the tank 3rd connected pump 5 , one with the pump 5 via a second line 6 connected first heat exchanger 7 and one to the first heat exchanger 7 downstream second heat exchanger 8th , as well as the second heat exchanger 8th downstream first turbine 9 with a first generator 10th .

At the outlet of the first turbine 9 closes a third line 11 and flows into the first heat exchanger 7 , which is the third heat exchanger 12th is connected downstream.
Downstream of the third heat exchanger 12th is on the third line 11 the first valve 3rd downstream. The third line 11 opens downstream of the first valve 3rd in the tank 3rd . Via the first valve 3rd According to the invention, the pressure of the fluid is reduced from supercritical pressure to the tank pressure level. At the tank 3rd closes a fourth line 14 and ends in the third heat exchanger 12th . Downstream of the third heat exchanger 12th is on the fourth line 14 a second valve 15 switched, via which the portion degassed by the pressure reduction via the third line 11 in the tank 3rd flowing fluids to the atmosphere or for further use by consumers of unpressurized air gases.

In the 2nd the circuit shown is optimized to reduce thermal stresses, those in the heat exchangers when operating with a higher inlet temperature into the turbine 9 may occur. The entry temperature into the turbine 9 is about heat input through stored heat or waste heat in the second heat exchanger 8th raised. In order to reduce the thermal stresses, especially when there are load changes, a warm first heat exchanger is used 7 and a cold fourth heat exchanger 17th used. The fifth heat exchanger 16 is an example here on the high pressure side between the fourth heat exchanger 17th and the first heat exchanger 7 has been switched and allows an additional reduction in temperature fluctuations within the first heat exchanger by heat input from the environment or heat dissipation to the environment 7 and the fourth heat exchanger 17th . Should not be a heat source with a higher temperature than the ambient temperature for the heat input into the second heat exchanger 8th are available, so the first heat exchanger 7 on the side of lower but supercritical pressure via the fifth line 18th be bypassed by the third valve 19th on the fifth line 18th opened and the fourth valve 20th in line 11 is closed, so that electrical power can be generated only with a heat input from the environment.

3rd shows an embodiment in which the outgassing of the first valve 13 escaping cryogenic fluid downstream of the first valve 13 in a degassing tank 21 instead of in the tank 3rd he follows. The liquid phase is through the sixth line 22 into which the fifth valve 23 is switched into the tank 3rd headed. The fourth line 14 closes on the degassing tank 21 instead of on the tank 3rd at.

The embodiment of the 4th serves to optimize efficiency. Instead of that from the third heat exchanger 12th escaping cryogenic fluid in the first valve 13 To relax at the tank pressure level, the fluid passes through a seventh line 24th to a second turbine 25th passed to a second generator 26 is coupled. From the exit of the second turbine 25th the cryogenic fluid passes through an eighth line 27 downstream of the first valve 13 to the third line 11 initiated which in the tank 3rd flows into. If the second turbine 25th is in operation, is the first valve 13 closed. The first valve 13 is used to start the system and in the event that the second turbine 25th is not available.

5 shows an embodiment with black start ability. A pressure tank 31 is on a ninth line 29 in which a sixth valve 30th is switched with the second line 6 connected. The ninth line 29 is used to fill the pressure tank 31 by the sixth valve 30th with the pump running 5 is opened and is closed after filling is complete. In addition, the bottom of the pressure tank 31 over the tenth line 32 in which a seventh valve 33 is switched with the second line 6 connected. A pressure build-up evaporator 34 , in which via an eighth valve 35 Liquid from the pressure tanks 31 can be initiated, is on the liquid and gas side with the pressure tank 31 connected. If electrical power is to be generated in the event of a black start, the seventh valve is used 33 opened, so even without a running pump 5 pressurized cryogenic fluid into the first turbine 9 leading second line 6 can be fed. The pressure in the pressure tank 31 through the pressure build-up evaporator operated with ambient heat 34 maintained by the amount to be evaporated required for pressure maintenance via the eighth valve 35 in the pressure build-up evaporator 34 is initiated. To prevent cryogenic fluid from flowing backwards over the non-running pump 5 in the tank 3rd is pressed is in the second line 6 downstream of the pump 5 and upstream of the ninth line branch 29 a check valve 28 switched.

The embodiment of the 6 serves to limit the oxygen concentration in the tank 3rd in the case of using liquid air as a cryogenic fluid. From the third line 11 branches downstream of the first turbine 9 an eleventh line 36 starting in the third turbine 39 which leads to a third generator 40 is coupled. Via the sixth heat exchanger, which is connected in the eleventh line upstream of the third turbine, the inlet temperature of the third turbine is determined with the aid of ambient heat, stored heat or low-value waste heat 39 raised. At the exit of the third turbine 39 closes a twelfth line 38 that leads to the atmosphere.

Reference list

1

Device for storing and storing electrical energy

2nd

Plant for the liquefaction of air gases

3rd

Liquefied air gas tank

4th

first line

5

pump

6

second line

7

first heat exchanger

8th

second heat exchanger

9

first turbine

10th

first generator

11

third line

12th

third heat exchanger

13

first valve

14

fourth line

15

second valve

16

fifth heat exchanger

17th

fourth heat exchanger

18th

fifth line

19th

third valve

20th

fourth valve

21

Outgassing tank

22

sixth line

23

fifth valve

24th

seventh line

25th

second turbine

26

second generator

27

eighth line

28

Check valve

29

ninth line

30th

sixth valve

31

Pressure tank

32

tenth line

33

seventh valve

34

Pressure build-up evaporator

35

Eighth valve

36

eleventh line

37

sixth heat exchanger

38

twelfth line

39

third turbine

40

third generator

Claims (16)

Device (1) for storing and withdrawing electrical energy, comprising a system for liquefying air gases (2), a tank (3) for liquefied air gases, a pump (5) connected to the tank (3) via a first line (4) ), a first heat exchanger (7) connected to the pump (5) via a second line (6) and a second heat exchanger (8) connected downstream of the first heat exchanger (7), and a first turbine (9) connected downstream of the second heat exchanger (8) ) with a first generator (10), characterized in that a third line (11) connects to the outlet of the first turbine (9) and opens into the first heat exchanger (7), the third line (11) downstream of the first heat exchanger (7) a third heat exchanger (12) is connected, a first valve (13) being connected downstream of the third heat exchanger (12) in the third line (11), the third line being downstream of the first vent ils (13) opens into the tank (3) for liquefied air gases and a fourth line (14) leads from the tank (3) for liquefied air gases to the third heat exchanger (12), the fourth line (14) downstream of the third heat exchanger (12) a second valve (15) is connected and the fourth line (14) leads to the atmosphere. Device after Claim 1 , The pump (5) is followed by a fourth heat exchanger (17), a fifth heat exchanger (16) being connected in the second line (6) between the fourth heat exchanger (17) and the first heat exchanger (7), the upstream of the first heat exchanger (7) branches off from the third line (11) a fifth line (18) which opens downstream of the first heat exchanger (7) into the third line (11), a third valve (19 ) is connected and a fourth valve (20) downstream of the branch of the fifth line (18) from the third line (11) and upstream of the junction of the fifth line (18) into the third line (11) into the third line (11) is switched, the fourth line (14) downstream of the third heat exchanger (12) opening into the fourth heat exchanger (17) and the second valve (15) downstream of the fourth heat exchanger (17) opening into the fourth line (14) is switched. Device after Claim 2 , wherein the third heat exchanger (12) and the fourth heat exchanger (17) are integrated in one component. Device according to one of the preceding claims, wherein the third line (11) opens into a degassing tank (21), to which a sixth line (22) adjoins, which opens into the tank (3) for liquefied air gases, the sixth line ( 22) a fifth valve (23) is connected and the fourth line (14) connects in the gas space of the outgassing container (21). Device according to one of the preceding claims, wherein upstream of the first valve (13) from the third line (11) branches off a seventh line (24) which opens into a second turbine (25) which is coupled to a second generator (26) , an eighth line (27) connecting to the outlet of the second turbine and opening downstream of the first valve (13) into the third line (11). Device according to one of the preceding claims, wherein a non-return valve (28) is connected in the second line (6) downstream of the pump (5), a ninth line (29) branching off from the second line (6) downstream of the non-return valve and into a pressure tank (31) opens, a sixth valve (30) being connected in the ninth line, a tenth line (32) connecting to the pressure tank (31), which opens downstream of the branch of the new line (29) into the second line (6), whereby a seventh valve (33) is connected into the tenth line (32), the pressure tank (31) being connected to a pressure build-up evaporator (34) heated by ambient air, and an eighth valve (35) being connected into the liquid-carrying line of the pressure build-up evaporator. Device according to one of the preceding claims, wherein downstream of the first turbine (9) branches off from the third line (11) an eleventh line (36) which leads to a third turbine (39) coupled to a third generator (40), upstream a sixth heat exchanger (37) is connected to the third turbine (39) in the eleventh line (36) and a twelfth line (38) is connected to the outlet of the third turbine (39) and leads to the atmosphere. Method for storing and withdrawing electrical energy, in which air gases are liquefied and stored in a tank (3) for storing electrical energy, and in which the stored liquid air gas is extracted via a second line (6) through a first heat exchanger (7) and a second heat exchanger (8) is pumped to a first turbine (9), the air gas being heated in the first heat exchanger (7) and second heat exchanger (8) and in the first turbine (9) for driving a first generator (10) is relaxed, the air gas emerging from the first turbine (9) first being fed to the first heat exchanger (7) and then to the third heat exchanger (12), the air gas emerging from the third heat exchanger (12) being cooled and liquefied via a first valve (13) to the pressure prevailing in the tank (3) for liquefied air gases and then into the tank (3) for liquefied Air gases is passed, the outgassed cryogenic portion of the air gas being fed to the third heat exchanger (12) and exiting partially heated from this third heat exchanger (12), and the outgassed portion of the air gas being blown off into the atmosphere via a second valve (15) . Procedure according to Claim 8 , wherein the outlet pressure from the first turbine (9) is higher than the critical pressure of the fluid used. Procedure according to one of the Claims 8 or 9 , the tank (3) being designed as a pressure tank. Procedure according to one of the Claims 8 or 9 , the tank (3) being designed as a flat-bottom tank. Procedure according to one of the Claims 8 to 11 , an air separation plant being used as the plant for liquefying air gases (2). Procedure according to one of the Claims 8 to 12th , the fourth line (14) leading into the warm part of an air separation plant. Procedure according to one of the Claims 8 to 13 The compression heat of a main air compressor of an air separation plant is used to raise the inlet temperature of the first turbine (9) via the second heat exchanger (8). Procedure according to one of the Claims 8 to 13 , With the second heat exchanger (8), stored heat from an electrothermal energy store is used to raise the inlet temperature of the first turbine (9). Procedure according to one of the Claims 8 to 15 , wherein the cryogenic fluid removed from the tank (3) is liquid nitrogen, liquid air, liquid oxygen or liquid argon.

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