DE202017004193U1 - Plant for storing and recovering energy - Google Patents

Abstract

System for storing and recovering energy, in particular electrical energy, which is set up for operation in a first operating mode and in a second operating mode, wherein means are provided which are configured to - in the first operating mode, use air with the use of electrical energy compressing to provide a liquid air product using at least a portion of the compressed air and at least partially storing the liquid air product in a tank system, in the second mode of operation at least partially storing the liquid air product stored in the tank system in the first operating mode to obtain a pressurized fluid heat and at least partially relax the pressurized fluid to recover electrical energy, - in the first mode of operation, to at least partially remove and store heat of compression in the compressed air after compression, and store it in a heat storage unit, and In the second mode of operation, to use the heat of compression temporarily stored in the heat storage unit in the first mode of operation to heat the liquid air product, characterized by an electric heater adapted to provide heat in the first mode of operation and means arranged therefor are to store the heat provided by the electric heater in the first operating mode at least partially in addition to the heat of compression in the heat storage unit.

Description

The present invention relates to a system for storing and recovering energy, in particular electrical energy.

State of the art

Systems for storing electrical energy in times of high electricity supply and for the recovery of the stored electrical energy in times of low electricity supply gain in importance, especially in view of the increasing use of non-baseload energy sources for power generation.

The storage and recovery of energy using liquid air is known and is referred to in English as Liquid Air Energy Storage (LAES). A corresponding plant is in the EP 3 032 203 A1 disclosed.

In times of high electricity supply, in LAES systems, in a first operating mode, air is condensed under power consumption, cooled, liquefied and stored in an insulated tank system. At times low supply of electricity in a second mode of operation stored in the tank system liquefied air, in particular after an increase in pressure by means of a pump, warmed and thus converted into the gaseous or supercritical state. A pressurized stream obtained thereby is expanded in an expansion turbine which is coupled to a generator. The electrical energy obtained in the generator is, for example, fed back into an electrical network.

A corresponding storage and recovery of energy is basically not only possible using liquid air. Rather, in the first mode of operation, other cryogenic liquids formed using air may be stored and used in the second mode of operation to generate electrical energy. Examples of corresponding cryogenic liquids are liquid nitrogen or liquid oxygen or

Component mixtures consisting predominantly of liquid nitrogen or liquid oxygen.

Conventional air separation plants can serve to provide the corresponding cryogenic liquids. If liquid air is used, it is also possible to use pure air liquefaction plants. As a generic term for air separation plants and air liquefaction plants, the term "air processing plants" is used below. The cryogenic liquids formed by such systems using air are hereinafter also referred to as "air products". In the context of the following explanations, if the term "LAES" is used in a simplified way, this term should also cover installations using other air products as part of the storage and recovery of energy. In addition to the cryogenic air product, further deep-frozen liquids can be stored in the tank system of an LAES plant, which can be evaporated in the second operating mode or converted into the supercritical state.

In related processes, external heat and fuel may be coupled to increase efficiency and output, particularly using a gas turbine whose exhaust gas is vented along with the pressure stream formed from the air product in the second mode of operation.

There is basically a need for further improvements in corresponding plants, in particular in order to increase their efficiency.

Disclosure of the invention

Against this background, a system for storing and recovering energy, in particular of electrical energy, with the features of claim 1 protection is proposed. Preferred embodiments are the subject of the following description.

In principle, in a system for storing and recovering energy, ie a LAES system, in which, as explained above, air is compressed in a first operating mode and the compressed air is used to form a cryogenic liquid air product, the compressed air is deprived of heat and be cached in a heat storage unit. The cached heat may then be used in the second mode of operation in the vaporization of the air product.

A basic idea of the present invention is, in this connection, to provide an additional electric heater which is set up to raise the temperature level at which the intermediate storage takes place in the heat storage unit, for example from 300 to 600 ° C. In this way, the system technology used is specifically cheaper because an electric heater offers corresponding cost advantages and the heat storage unit is better utilized due to the higher temperature. Furthermore, the use of an electric heater causes a faster variable electrical power consumption, so that overall a highly dynamic Operation mode and the thermal capacity is better used. The advantages mentioned outweigh any possibly lower efficiency by a few percentage points.

For example, is from the DE 10 2014 008 120 A1 a system is known which is set up for storing electrical energy by means of gas compression. In this, a gas, preferably ambient air in the normal state, compressed, heat of compression is dissipated, the gas is at least once further compressed, it is discharged again heat of compression and the compressed gas is stored in a gas pressure accumulator. If required, the compressed gas is discharged and released. It is envisaged that when dissipating the heat of compression, they are transferred to a storage medium and the storage medium is stored in at least one heat accumulator. When storing the storage medium, the temperature of the storage medium is at least partially raised by means of a heater from an initial temperature to a storage temperature. The thus stored heat of compression is used for the heating of the gas during expansion of the compressed gas. The present invention employs appropriate heating associated with the storage and vaporization of a liquid air product.

In known LAES systems, the freezing during the transfer of the liquid air product in the gaseous or supercritical state during the second mode of operation can be stored and used during the first operating mode to provide cold for the recovery of the air product. So is out of the WO 2014/026738 A2 It is known to cool the compressed feed air used to recover the air product in the energy storage period countercurrent to two cooled organic refrigerants at two different temperature levels and to heat the described cryogenic process liquid against the then heated refrigerant in the energy recovery period, whereby the refrigerants are cooled again. The development of a corresponding system is, as with reference to the attached 1A and 1B explained, provided in an embodiment of the present invention.

If a "power generation unit" is referred to below, this is understood to mean an installation or an installation part which is or is set up to generate electrical energy. In the context of the present invention, an energy-generating unit typically comprises at least one expansion turbine, which is advantageously coupled to at least one electric generator. A relaxation machine coupled to at least one electric generator is commonly referred to as a "generator turbine". The mechanical power released during the expansion of a pressurized fluid, which is formed at least partially using the air product, in the at least one expansion turbine or generator turbine can be converted into electrical energy in the generator (s) of the energy production unit.

The production of air products in the liquid or gaseous state by cryogenic separation of air in air separation plants is known and, for example at H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH, 2006, especially Section 2.2.5, "Cryogenic Rectification" , described. Air separation plants have distillation column systems which can be designed, for example, as two-column systems, in particular as classic Linde double-column systems, but also as three-column or multi-column systems. In addition to the distillation columns for the recovery of nitrogen and / or oxygen in the liquid and / or gaseous state (for example, liquid oxygen, LOX, gaseous oxygen, GOX, liquid nitrogen, LIN and / or gaseous nitrogen, GAN), ie the distillation columns for nitrogen-oxygen Separation, distillation columns can be provided for obtaining further air components, in particular the noble gases krypton, xenon and / or argon.

The present invention involves the recovery of an air product using compressed feed air. The plants or plant components used for this purpose, as already mentioned above, here summarized under the concept of "air handling plant". This is understood in the parlance of the present application, a plant which is set up to obtain at least one air product using compressed feed air. Sufficient for a processing plant for use in the present invention, it is that a corresponding cryogenic air product can be obtained by this, which can be used as a storage liquid and transferred to a tank system. This may be an air separation plant, as explained above, but also, as mentioned, merely a pure air liquefaction plant which does not have a distillation column system. Incidentally, the structure of an air liquefaction plant may correspond to that of an air separation plant with the discharge of an air product. Of course, liquid air can be generated as an air product in an air separation plant.

The provision of the compressed feed air, from in the corresponding Air handling equipment an air product is produced, can be in a known main (air) compressor with booster or any other device for the condensation of air done, as can also be used in conventional air separation plants. For details refer to the literature cited with reference to air separation plants.

An "air product" is any product that can be produced, at least by compressing and cooling air, and in particular, but not necessarily, by subsequent cryogenic rectification. In particular, these may be liquid or gaseous oxygen (LOX, GOX), liquid or gaseous nitrogen (LIN, GAN), liquid or gaseous argon (LAR, GAR), liquid or gaseous xenon, liquid or gaseous krypton, liquid or gaseous neon , liquid or gaseous helium, etc. but also, for example, liquid air (LAIR). The terms "oxygen", "nitrogen", etc. are intended to denote in each case also cryogenic liquids or gases which have the respective air component in an amount which is above that atmospheric air. It does not have to be pure liquids or gases with high contents.

A "heat exchanger" is used for the indirect transfer of heat between at least two z. B. countercurrently guided to each other streams, such as a warm compressed air stream and one or more cold streams or a cryogenic liquid air product and one or more hot streams. Typically countercurrent heat exchangers are used in the context of the present invention. A heat exchanger may be formed from a single or a plurality of parallel and / or serially connected heat exchanger sections, for. B. from one or more plate heat exchanger blocks or wound heat exchangers. An arrangement referred to herein as a "heat exchange unit" may include one or more heat exchanger blocks or one or more heat exchangers.

The present application uses the terms "pressure level" and "temperature level" to characterize pressures and temperatures, thereby indicating that corresponding pressures and temperatures in a given plant need not be used in the form of exact pressure or temperature values. However, such pressures and temperatures typically range in certain ranges that are, for example, ± 1%, 5%, 10%, 20% or even 50% about an average. Corresponding pressure levels and temperature levels can be in disjoint areas or in areas that overlap one another. In particular, for example, pressure levels include unavoidable or expected pressure drops, for example, due to cooling effects. The same applies to temperature levels.

Advantages of the invention

The present invention is based on a system for storing and recovering energy, in particular electrical energy, which is set up for operation in a first operating mode and in a second operating mode. This plant comprises means adapted to compress air in the first mode of operation using electrical energy, to provide a cryogenic liquid air product using at least a portion of the compressed air, and to at least partially store the liquid air product in a tank system , Furthermore, the system has means which are set up in the second operating mode to heat the liquid air product stored in the first operating mode in the tank system at least partially to obtain a pressurized fluid and to convert it into the gaseous or supercritical state and at least partially submerge the pressurized fluid Gaining electrical energy to relax. A corresponding "pressurized fluid" can, as already mentioned, be present in a gaseous or supercritical state. As also mentioned, it is also possible in corresponding systems to store further cryogenic liquids in the tank system. These can also be used in the second operating mode in the formation of the pressurized fluid. Even in such a case, however, the liquid air product stored in the first operating mode in the tank system is at least partially heated to obtain the pressurized fluid and transferred to the gaseous or supercritical state.

A corresponding system further comprises means which are adapted to extract in the first operating mode of the compressed air after compression at least partially heat of compression and buffered in a heat storage unit. A corresponding heat storage unit may for example comprise one or more heat storage fluids, which in turn under Use of the condensed air extracted heat of compression can be heated. Suitable heat storage fluids are, for example, pressureless and pressurized water, thermal oils and molten salts. In principle, however, it is also possible to form a heat storage unit as a fixed bed storage unit, in which case instead of a heat storage fluid, a solid material, such as a stone or gravel, ceramic or concrete blocks or aluminum and / or Stahlfüllkörper, for example in the form of scrap to Heat storage is used and heated using the condensing air extracted heat of compression. In the context of the present invention, means are furthermore provided which are set up, in the second operating mode, to use the heat of compression temporarily stored in the heat storage unit in the first operating mode at least partially for heating the liquid air product.

According to the invention, such a system has an electrical heater arranged to provide heat in the first mode of operation, and means adapted to heat the electrical heater provided in the first mode of operation at least partially in addition to the heat of compression in the thermal storage unit save.

There are basically several options for positioning or for the use of a corresponding electric heater possible, which are also explained below with reference to the accompanying drawings. For example, in the context of the present invention, an electric heater can be used so that it heats the compressed air after compression. For this purpose, for example, the compressed air can be passed through heating channels of an electric heater, which can be heated, for example, resistively or inductively. In this way, the compressed air is acted upon by both the heat of compression and with the heat additionally provided by the electric heater or in each case a part thereof. The entire heat or a corresponding part can be transferred into the heat storage unit in the manner explained below. Alternatively, it is also possible to provide the heat storage unit itself with a corresponding electric heater, for example, by suitable electric heating coils, which are guided through a container in which a heat storage fluid is kept, or by appropriate heating coils, which are arranged in a fixed bed storage are. An inductive heating of a suitable heat exchange unit is basically possible. In this way, only the heat of compression or a part thereof is transported to the heat exchange unit by the compressed air.

The heat of compression can be supplied directly to the heat storage unit in the context of the present invention in that the compressed air or the pressure fluid is passed through a corresponding heat storage unit. For example, the already mentioned container, in which a heat storage fluid is kept ready to be provided with passages through which the compressed air can be passed. The same is possible in a comparable manner even when using fixed bed storage. In order to ensure a particularly good heat exchange with the heat storage fluid or the fixed bed storage, appropriate channels or passages with surface-enlarging structures, such as rib structures, as they can be used in principle in heat exchangers, be provided.

However, it can also be provided in principle to carry out an indirect heating of the heat storage unit, in particular by an intermediate circuit between a heat exchanger, which is in the heat exchanger with the compressed air or the pressure fluid, and the heat storage unit, in which optionally a further heat exchanger can be provided provided.

The present invention may in particular be configured such that the compressed air is cooled in a first heat exchange unit of a heat exchange system in the first operating mode in countercurrent to a heat transfer fluid and the liquid air product is heated in the first heat exchange unit in the second operating mode in countercurrent to the heat transfer fluid, such as especially in the EP 3 032 203 A1 explained. The use of a heat transfer fluid has in the context of this embodiment of the present invention has the particular advantage that additional organic refrigerant, which may contain flammable hydrocarbons are not passed through the same heat exchanger as the compressed air or the pressure fluid and therefore not compressed in leaks with oxygen Air or the pressurized fluid, as far as contained therein, can come into contact. For this purpose, the heat transfer fluid used is preferably free of or poor in oxidizing and combustible components, in particular oxygen-free in the sense explained below. The heat transfer fluid is thus advantageously neither fire-promoting nor self-combustible, "fire-promoting" a property is understood to maintain under the prevailing conditions in a corresponding heat exchanger combustion even in the absence of atmospheric oxygen.

Furthermore, in a further development of the embodiment just described, the present invention provides that the heat transfer fluid is cooled and heated in the second operating mode at least in part by means of at least two further heat exchange units of the heat exchange system operated at different temperature levels and with at least one organic refrigerant becomes. In this case, it can be provided, in particular, that the directions in which the heat carrier fluid and the compressed air are guided through the first heat exchange unit in the first operating mode are opposite to the directions in which the Heat transfer fluid and the pressurized fluid are passed through the first heat exchange unit in the second operating mode. This makes it possible, in each case the temperature profiles, according to which a cooling or heating of corresponding fluids takes place close to each other, because the heat transfer fluid and the feed gas, which flow in countercurrent to each other through the first heat exchange unit, each with the lowest possible temperature difference passed through them can be.

In the embodiment just described, the invention further provides, in particular, for the heat transfer fluid and the compressed feed gas to be passed through the first heat exchange unit at a first pressure level and the heat transfer fluid and the process fluid are passed through the first heat exchange unit at a second pressure level in the second operating mode first pressure level is at least 5 bar above the second. In other words, the operating pressures of the heat transfer fluid are different in the first and second modes of operation. For this purpose, a pressure control device can be provided. The pressure of the heat transfer fluid depends in each case on the pressure of the feed gas or the process liquid in the first heat exchange unit, so that a particularly effective heat transfer is also possible for this reason. In principle, however, it is also possible to use equal pressure levels in the first and the second operating mode or a lower pressure level in the second operating mode than in the first operating mode.

The present invention thus provides in the embodiments just described, in addition to the liquid air product, which is provided using the compressed air and stored in the first operating mode and evaporated in the second operating mode or in the supercritical state, further cold storage fluids in the form of provide organic refrigerant, which are not formed from the compressed air. The at least two further cold storage fluids, ie the organic refrigerants, are preferably configured to store cold at different temperature levels, ie they have different boiling points, for example, which make them suitable for use at different temperatures. In this way, the cooling of the compressed feed gas in the first operating mode is particularly efficient. The same applies to the heating of the cryogenic process fluid in the second operating mode. Overall, the present invention allows a particularly efficient operation by using a total of at least three cold storage fluids, namely the liquid air product formed using the compressed air, and the at least two organic refrigerants, for example hydrocarbons.

As already explained, an oxygen-free or essentially oxygen-free gas mixture is advantageously used as the difficultly or non-inflammable heat transfer fluid. It is understood that a correspondingly "oxygen-free" gas mixture may also contain residual oxygen contents, for example 1%, 0.5%, 0.1% or 0.01% oxygen or less. Correspondingly low oxygen contents sufficiently reduce the risk of ignition when in contact with a flammable organic refrigerant.

In principle, additionally or at least partially as an alternative to the use of corresponding liquid media, it is also possible to use fixed-bed cold storage devices which can be designed as described above for the heat storage. These can also be operated at different temperature levels and be designed with and without safety intermediate circuit, for example with nitrogen as the heat transfer fluid. The person skilled in the art makes the combination of liquid and fixed bed cold storage as required.

For further embodiments, which in the context of the embodiments just described in the context of the present invention, in principle, also individually or in combination, are possible on the EP 3 032 203 A1 in particular with reference to the local embodiments, referenced.

The invention and preferred embodiments of the invention will be explained in more detail with reference to the accompanying drawings.

Brief description of the drawings

1A FIG. 2 illustrates a system which can be further developed according to the invention in a first operating mode on the basis of a process flow diagram, FIG.

1B illustrates the system according to 1A in a second mode of operation based on a process flow diagram.

2 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

3 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

4 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

5 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

6 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

7 1 illustrates a plant according to an embodiment of the invention, a second operating mode based on a process flow diagram.

Detailed description of the drawings

In the figures, corresponding elements and fluid streams are illustrated with identical reference numerals. In all figures, systems or plant components are illustrated in different operating modes, which in addition to the elements shown have other elements such as valves and valves. Corresponding valves and fittings are not illustrated for the sake of clarity, for illustration, however, blocked by valves and valves fluid paths or correspondingly inactivated currents are shown crossed. Mainly or exclusively gaseous streams are illustrated in the form of unfilled (white) arrow triangles, predominantly or exclusively liquid streams in the form of filled (black) arrow triangles. The invention will be illustrated with reference to an air treatment unit as a gas treatment unit.

The 1A and 1B illustrate a plant, which can be further developed according to an embodiment of the invention, in a first ( 1A ) and in a second operating mode ( 1B ) using process flow diagrams.

In the in 1A operating mode shown is feed air in the form of a current a by means of a main air compressor 2 with not separately designated intercoolers through a filter 1 sucked. The feed air of stream a is in the main air compressor 2 For example, compressed to a pressure of about 5 to 7 bar. A correspondingly compressed stream, now denoted b, becomes a cooling unit operated with cooling water streams which are not separately designated 3 fed, where the current b is removed from the previously supplied heat of compression. A correspondingly cooled stream, now designated c, is placed in an adsorptive cleaning unit 4 , which may comprise, for example, a pair of molecular sieve filled, not separately designated Adsorberbehälter, freed of the majority of the water contained and carbon dioxide. A stream purified in this way, now denoted d, becomes a re-compressor 5 fed and nachverdichtet in this to a pressure of, for example, about 9 bar. A correspondingly recompressed stream, now denoted by e, is in a heat exchange system, which here with a total of 10 is designated, fed.

In the heat exchange system 10 becomes the compressed feed air of the stream e in a first heat exchange unit 11 cooled against a flow f of a heat transfer fluid to obtain a corresponding cooled stream g. The cooled stream g is in the example shown in a generator turbine 12 and possibly one of these downstream, not separately designated expansion valve relaxes. The correspondingly relaxed stream g is transferred to a separator tank 13 in whose sump a liquid fraction and at whose head a gaseous fraction is formed. The liquid fraction from the bottom of the separator tank 13 is in the form of the stream h in a tank system 20 in which it is stored in the first operating mode. The tank system 20 In addition to the stream h, as already mentioned above, it can also be charged with further liquid cryogenic streams. The tank system 20 In the first mode of operation no fluid is withdrawn in the example shown.

The gaseous fraction from the top of the separator tank 13 is withdrawn in the form of the current i and in a further heat exchange unit 14 here opposite the second and third heat exchange units discussed below 16 and 18 as fourth heat exchange unit 14 is called, heated. In the fourth heat exchange unit 14 In this case, cooling of the current i can be transferred to a current k, which likewise comprises a heat transfer fluid and is combined with a further corresponding current I to the already mentioned current f of the heat transfer fluid. By the current f and the currents k and l partial circuits of a heat transfer fluid are formed by means of a pump 15 be driven and in this, as well as in the first heat exchange unit 11 , are linked together. It should be emphasized that in the mentioned subcircuits no cold-performing expansion of a corresponding heat transfer fluid takes place, this serves essentially only for the transfer of heat, but not for their production.

The current I is before the connection to the stream f and the feed into the heat exchanger 11 by means of the pump 15 , or after the division of the flow f into the flows k and l downstream of the heat exchange unit 11 , ie at its warm end, by the already mentioned two further heat exchange units 16 and 18 namely, a second heat exchange unit 16 and the third heat exchange unit 18 , in which the current l respectively by means of organic refrigerant, each by means of refrigerant units 17 and 19 be prepared, is cooled. Details of the heat exchange units 16 and 18 and the refrigerant units 17 and 19 are for example with reference to the 2A and 2 B such as 3A and 3B in the EP 3 032 203 A1 explained.

To provide additional cooling, a partial flow m can be branched off from the compressed feed air of the flow d, in the heat exchanger 14 Cooled to an intermediate temperature, cooled in a non-designated generator turbine and cooled by the heat exchanger 14 to be led back. A correspondingly recirculated stream can, for example, in the form of stream n as a regeneration gas in the adsorptive cleaning unit 4 be used. The current i can, for example, upstream of the booster 5 be combined with the stream d.

In the in 1B shown second operating mode of the system, the stream e is not provided, the main compressor 2 and the re-compressor 5 may be out of order or operated in a standby mode. The adsorptive cleaning device 4 can during the in 1B illustrated second operating mode, for example, be regenerated. Accordingly, in the generator turbine 12 also no cooled, compressed feed air relaxed and no fluid in the tank system 20 transferred. Also in the first operating mode according to 1A by the flow k realized refrigerant circuit through the fourth heat exchange unit 14 here is typically not in operation.

Instead, in the second mode of operation according to 1B the tank system 20 Fluid in the form of the current o, so a storage fluid, taken and provided in the form of a cryogenic process fluid. In the first operating mode according to 1A was in the tank system 20 a cryogenic air product from the bottom of the separator tank 13 fed. The current o becomes in the second operating mode in the heat exchanger 11 heated and evaporated or, at the appropriate pressure, transferred to the supercritical state. The current o transmits its coldness to a flow p, which consists of the same heat transfer fluid of the flows f, k and l of the first operating mode 1A is formed here, but here for the better distinctness is called divergent. One in the second operating mode according to 1B The refrigerant circuit realized by the current p also includes the aforementioned second and third heat exchange units 16 and 18 or the associated refrigerant units 17 and 19 ,

By heating and evaporating the stream o, ie the cryogenic process liquid, a gaseous or supercritical pressurized fluid in the form of the stream q is provided, that of a power generation unit 120 is supplied. In the power generation unit 20 the current q is generated to generate electrical energy in a generator turbine 21 relaxed. A correspondingly relaxed fluid flow is designated by r. The stream q can previously through a heat exchanger 22 guided and in this by means of an exhaust gas flow of a combustion chamber 23 or a heat engine, in particular a gas turbine, in which a fuel is burned with air or other oxygen-containing gas, are heated.

In 2 a system according to an embodiment of the invention is illustrated. This installation can, with the exception of the following, additional elements, basically comparable to those in the 1A and 1B be constructed plant, also here a (in 2 simplified) main air compressor 2 is provided, which sucks the air flow a. Other elements like the one in the 1A and 1B shown filters 1 as well as the aftercooler 3 , the facilities 4 for air purification and the booster 5 are not shown here. As part of a heat exchange system, which is basically comparable to the heat exchange system 10 according to the 1A and 1B may be formed, for the sake of clarity, only a heat exchange unit 110 and a heat exchange unit 140 shown, which are essentially the heat exchange units 11 and 14 according to 1A and 1B can correspond. Also the other elements of the heat exchange system 10 according to the 1A and 1B may be present and operated in accordance with or in a similar manner. The same applies to the following figures, but the heat exchange system can also be designed differently. The essential function of the heat exchange unit 140 is the liquefaction, the essential function of the heat exchange unit 110 the evaporation, wherein a heat exchange or an intermediate storage of deprived of heat during cooling for evaporation can take place.

The presentation in the 2 As well as the following figures shows both operating modes, it being understood that in each of the two operating modes only certain system components are in operation, as previously with reference to the 1A and 1B explained. Thus, they are also in 2 and in the following figures fluid flows a, b, q and r typically each used or provided only in one of the operating modes.

According to 2 is an electric heater 41 provided by the main air compressor 2 compressed air stream b, which already by the compression of the main air compressor 2 has undergone warming, further heated. In a heat exchanger 42 is the heat of compression and the additional, in the electric heater 41 transferred to the compressed air flow b heat at least partially removed from the compressed air flow b and in a heat storage unit 40 , which may be formed as explained above, transmitted.

The heat transfer into the heat storage unit 40 usually takes place exclusively in the first operating mode. Typically, only in the second mode of operation, heat is removed from the heat storage unit 40 by means of a heat exchanger 43 for example, transferred to the gaseous or supercritical fluid pressure of the current q. Also, transmission to other fluid streams used to provide a corresponding flow is possible.

While 2 an indirect transfer of heat into the heat storage unit 40 illustrates, for example via the use of heat transfer fluids, it is also possible in principle, the compressed air flow b and the flow q or these corresponding fluid flows directly through the heat storage unit 40 respectively. This embodiment of the present invention is in 3 illustrated by a corresponding process flow diagram.

According to another, in 4 illustrated embodiment, it is also possible, the compressed air flow b first by one of the better distinctness with half 44 to lead designated heat exchanger and only then by means of the electric heater 41 to warm up. The correspondingly heated compressed air flow b can subsequently through the heat storage unit 40 guided and via a not separately designated pump through the heat exchanger 44 pumped and then the liquefaction unit using the heat exchanger described several times 14 be supplied.

The same applies in a comparable manner for the pressurized fluid of the stream q, the first through a heat exchanger 45 passed, then by means of a pump through the heat storage unit 40 guided, and over the heat exchanger 45 the relaxation is supplied.

According to the in the 5 and 6 illustrated embodiments, there is no heating of the compressed air streams b. Rather, here (not separately designated and illustrated only in the form of a voltage arrow) electrical heaters are provided for heating the material of the heat storage units 40 are set up. Otherwise, the explanations regarding the 2 and 3 corresponding.

According to the in 7 illustrated further embodiment of the present invention is a combined cold and heat storage unit 50 provided, wherein the cold storage unit again as in the previously described embodiments and in particular according to the 1A and 1B may include a number of other components. The compressed air flow b, here in particular by the electric heater 41 can be heated (but also an embodiment without a corresponding heating is possible), is comparable to that in in 2 illustrated embodiment, by a heat exchanger 42 led, where the compressed air flow b withdrawn heat and in the heat storage unit 40 can be transferred. The in the heat exchanger 42 cooled compressed air flow is in the liquefaction unit or their exemplified here heat exchanger 14 liquefied. During liquefaction, a heat exchanger with the cold storage unit takes place here through the heat exchanger 11 is illustrated.

The embodiment according to 7 finds particular application when a liquid cold storage medium is used in the cold storage unit, such as propane. In this case, a connection of the cold storage unit is typically provided via an intermediate circuit for safety reasons. Again, the above to the embodiments according to 3 to 6 explained embodiments such as direct indirect heating and the heating in the heat exchange unit 40 be provided by the electric heater.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 3032203 A1 [0003, 0028, 0034, 0049]
• DE 102014008120 A1 [0013]
• WO 2014/026738 A2 [0014]

Cited non-patent literature

• H.-W. Häring (ed.), Industrial Gases Processing, Wiley-VCH, 2006, especially Section 2.2.5, "Cryogenic Rectification" [0016]

Claims (1)

System for storing and recovering energy, in particular electrical energy, which is set up for operation in a first operating mode and in a second operating mode, wherein means are provided which are set up for In the first mode of operation, to compress air using electrical energy, to provide a liquid air product using at least a portion of the compressed air, and to store the liquid air product at least partially in a tank system, In the second mode of operation, at least partially warming the liquid air product stored in the tank system in the first operating mode to obtain a pressurized fluid and at least partially relaxing the pressurized fluid to generate electrical energy, - In the first operating mode of the compressed air after compression at least partially remove heat of compression and buffer in a heat storage unit, and In the second operating mode, to use the heat of compression temporarily stored in the heat storage unit in the first operating mode, at least partly for heating the liquid air product, marked by An electrical heater configured to provide heat in the first mode of operation, and means configured to store the heat provided by the electrical heater in the first operating mode at least in part in addition to the heat of compression in the thermal storage unit.

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