EP2835506A1 - Method for generating electrical energy and energy generation system - Google Patents

Abstract

A method of generating electrical energy in a combined power plant (100, 200) comprising an air handling unit (10) and a power plant unit (20) is proposed. In a first operating mode (liquefaction operation), a first warm compressed air flow (f) is cooled in a heat exchanger system (15) of the air treatment unit (10) to a first cold compressed air flow (h), wherein the first cold compressed air flow (h) is a first cryogenic liquid flow (i) is produced and transferred to a liquid reservoir (17) of the air treatment unit (10). In a second operating mode (removal operation), a second warm compressed air flow (b) in the heat exchanger system (15) is cooled to a second cold compressed air flow (m), the second cold compressed air flow (m) being carried in a cold compressor system (16) of the air treatment unit (10). is compressed to a first high pressure stream (s). In the second mode of operation, a second cryogenic liquid stream (p) is further withdrawn from the storage tank (17) and vaporized or pseudo-evaporated in the heat exchanger system (15) to a second high pressure stream (s), the first and second high pressure streams (15). s) are combined to form a collecting stream (t). Finally, in the second operating mode, the collecting stream (t) or a stream (u) derived therefrom is expanded in at least one turbine (23) of the power station unit (20) coupled to a generator (G). It is provided that the first warm compressed air flow (f) in the first operating mode in the heat exchanger system (15) is cooled at least in part against a flow (k) of a liquid refrigerant. It is further provided that the second cryogenic liquid stream (p) in the second operating mode in the heat exchanger system (15) is at least partially heated against a flow (k) of the liquid refrigerant. A power generation plant (100, 200) is also an object of the invention.

Description

The invention relates to a method for generating electrical energy in a combined power generation plant comprising an air treatment unit and a power plant unit, and a corresponding power generation plant according to the preambles of the independent claims.

State of the art

For example DE 31 39 567 A1 and WO 2007/096656 A1 It is known to use liquid air or liquid nitrogen, ie cryogenic air liquefaction products, for grid control and for the provision of control power in power grids.

At low flow times or excess flow times, air in an air separation plant with an integrated condenser or in a dedicated liquefaction plant, generally referred to herein as an air treatment unit, is liquefied in whole or in part to form such an air liquefaction product. The air liquefaction product is stored in a tank system with cryogenic tanks. This mode of operation is referred to herein as "liquefaction operation".

At peak load times, the air liquefaction product is withdrawn from the tank system, pressure increased by a pump and warmed to about ambient temperature or higher and thus converted to a gaseous or supercritical state. A thus obtained high-pressure stream is expanded in a power plant unit in an expansion turbine or more expansion turbines with reheating to ambient pressure. The thereby released mechanical power is converted into electrical energy in one or more generators of the power plant unit and fed into an electrical grid. This mode of operation is referred to herein as "picking operation".

Corresponding methods and devices, as well as the method and the device of the invention, in principle also with an air liquefaction product working, which contains more than 40 mole percent oxygen. However, this has been excluded here in order to avoid confusion with methods and apparatus in which a particularly oxygen-rich fluid is introduced to promote oxidation reactions in a gas turbine.

The released during the transfer of the air liquefaction product in the gaseous or supercritical state cold can also be stored during the extraction operation and used during the liquefaction operation to provide cold for the recovery of the air liquefaction product.

Finally, compressed air storage power plants are known in which the feed air is not liquefied, but compressed in a compressor and stored in an underground cavern. In times of high electricity demand, the compressed air from the cavern is directed into the combustion chamber of a gas turbine. At the same time, the gas turbine is supplied via a gas line fuel, such as natural gas, and burned in the atmosphere formed by the compressed air. The formed exhaust gas is expanded in the gas turbine, thereby generating energy.

The economics of such methods and devices are greatly affected by the overall efficiency. The invention has for its object to improve appropriate methods and devices in their economics.

Disclosure of the invention

This object is achieved by a method for generating electrical energy in a combined power generation plant comprising an air treatment unit and a power plant unit, and a corresponding power generation plant having the features of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

Before explaining the features and advantages of the proposed measures according to the invention, some terms used below are explained.

A "power station unit" is understood here to mean a system or a system component which is or is set up for the generation of electrical energy. A power plant unit comprises at least one expansion turbine, which is coupled to at least one generator. The released during the relaxation of a fluid in the at least one expansion turbine mechanical power can therefore be converted into electrical energy.

An "air treatment unit" is understood here to mean an installation which is set up for the purpose of obtaining at least one "air liquefaction product" from air. As explained above, this can be an air separation plant which can be set up to obtain corresponding air fractions or else only a liquefaction unit of such a plant or a dedicated liquefaction unit. Sufficient for an air treatment unit for use in the present invention is that it can be obtained by this a corresponding cryogenic air liquefaction product, which can be used as a storage liquid and transferred to a tank system. An "air separation plant" is charged with atmospheric air and has a distillation column system for decomposing the atmospheric air into its physical components, particularly nitrogen and oxygen. For this purpose, the air is first cooled to near its dew point and then introduced into the distillation column system. For example, methods and apparatus for cryogenic separation of air are known Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, chapter 4 (pages 281 to 337 ) known. In contrast, an "air liquefaction plant" does not include a distillation column system. Incidentally, their structure corresponds to that of an air separation plant with the delivery of an air liquefaction product. Of course, liquid air can be generated as a by-product in an air separation plant.

An "air liquefaction product" is any product that can be produced, at least by compressing, cooling, and then deflating air in the form of a cryogenic liquid. In particular, an air liquefaction product may be liquid air, liquid oxygen, liquid nitrogen and / or a liquid noble gas such as liquid argon. The terms "liquid oxygen" and "liquid nitrogen" in each case also designate a cryogenic liquid which has oxygen or nitrogen in an amount above that atmospheric air lies. It does not necessarily have to be pure liquids with high contents of oxygen or nitrogen. Liquid nitrogen is thus understood to mean either pure or substantially pure nitrogen, as well as a mixture of liquefied air gases whose nitrogen content is higher than that of the atmospheric air. For example, it has a nitrogen content of at least 90, preferably at least 99 mole percent.

Under a "cryogenic" liquid, or a corresponding fluid, air liquefaction product, electricity, etc., a liquid medium is understood, the boiling point is well below the respective ambient temperature and, for example, 200 K or less, in particular 220 K or less. Examples of such cryogenic media are liquid air, liquid oxygen and liquid nitrogen.

A "heat exchanger system" is used to transfer heat indirectly between at least two countercurrent streams, such as a warm compressed air stream and one or more cold streams or a cryogenic air liquefaction product, and one or more hot streams. A heat exchanger system may be formed of a single or multiple heat exchanger sections connected in parallel and / or in series, e.g. from one or more plate heat exchanger blocks.

A "compressor system" is a device designed to compress at least one gaseous stream from at least one inlet pressure at which it is supplied to the compressor system to at least one final pressure at which it is taken from the compressor system. The compressor system forms a structural unit, which, however, can have a plurality of "compressor stages" in the form of known piston, screw and / or Schaufelrad- or turbine assemblies (ie radial or Axialverdichterstufen). In particular, these compressor stages are driven by means of a common drive, for example via a common shaft and / or a common electric motor. Several compressor systems, for example a main compressor and a secondary compressor of an air treatment unit, can form a "compressor arrangement".

A "cold compressor system", such as the compressor systems just discussed, may have one or more compressor stages driven by a common shaft, is a compressor system that compresses gas streams in the cryogenic state. Cold compressors are characterized in particular by at least one radial compressor stage, a low-temperature housing and / or an electric drive unit with integrated storage.

A "single cold compressor system" or a "single compressor system" is designed as a structural unit, which is present only once in a corresponding system, but may include one or more compressor stages. If several compressor stages are provided, these are coupled via a common shaft to a common compressor drive. The single cold compressor system or the single compressor system fluid is supplied in particular in the form of only one fluid stream, which is compacted with the one compressor stage in one step or with multiple compressor stages successively in several steps.

An "expansion turbine", which can be coupled via a common shaft with other expansion turbines or energy converters such as oil brakes, generators or compressor stages, is set up for the relaxation of a gaseous or at least partially liquid stream. Partial expansion turbines may be designed for use in the present invention as a turboexpander. If one or more expansion turbines designed as turboexpanders are coupled to one or more compressor stages, for example in the form of centrifugal compressor stages, and if necessary mechanically braked, but these are operated without externally supplied energy, for example by means of an electric motor, the term "booster turbine" is used for this purpose. used. Such a booster turbine compresses at least one current by the relaxation of at least one other current, but without external, for example by means of an electric motor, supplied energy.

In the context of the present application, a "gas turbine" is understood to mean an arrangement of at least one combustion chamber and at least one of these downstream expansion turbines (the gas turbine in the narrower sense). In the latter, hot gases are released from the combustion chamber to perform work. A gas turbine may further comprise at least one of the expansion turbine via a common shaft driven compressor stage, typically with at least one radial compressor stage, have. Some of the mechanical energy generated in the expansion turbine is usually used to drive the at least one compressor stage. Another part is regularly converted to generate electrical energy in a generator.

As a modification of a gas turbine, a "combustion turbine" only has the aforementioned combustion chamber and one of these downstream expansion machine. A compressor is usually not provided.

In contrast to a gas turbine, instead of a combustion chamber, a "hot gas turbine" has a heater. A hot gas turbine can be designed in one stage with a heater and an expansion turbine. Alternatively, however, several expansion turbines, preferably with intermediate heating, may be provided. In any case, in particular downstream of the last expansion turbine, a further heater can be provided. The hot gas turbine is also preferably coupled to one or more generators for generating electrical energy.

In the context of this application, a "heater" is understood to mean a system for indirect heat exchange between a heating fluid and a gaseous fluid to be heated. By means of such a heater, residual heat, waste heat, process heat, solar heat, etc. can be transferred to the gaseous fluid to be heated and used for energy generation in a hot gas turbine.

A "waste heat steam generator", also referred to as a heat recovery steam generator (HRSG), is capable of generating steam by heating water or for further heating, e.g. from cold steam to superheated steam, by means of a waste heat stream, for example one of a still hot or postheated gas stream downstream of a gas turbine or hot gas turbine.

In the context of the present invention, a "tank system" is understood to mean an arrangement having at least one cryogenic storage tank which is designed to store a cryogenic air liquefaction product. A corresponding tank system has insulation means and is mounted, for example, together with an air treatment unit in a cold box.

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 to realize the innovative concept. 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 pressure drops or expected pressure drops, for example, due to cooling effects. The same applies to temperature levels. The pressure levels indicated here in bar are absolute pressures.

If cryogenic air liquefaction products or corresponding liquid streams are "converted into a gaseous or supercritical state by heating in the context of the present application, this includes, on the one hand, a regular phase transition by evaporation, if this takes place at subcritical pressure. However, if such cryogenic air liquefaction products or corresponding liquid streams are heated at a pressure which is above the critical pressure, when heated above the critical temperature, no phase transition in the strict sense, but a transition from the liquid to the supercritical state, for which here Term "pseudoevaporating" is used.

For the purposes of this application, a "collecting stream" is understood to mean a total of two or more streams, for example two or more compressed air streams at the same or different pressure, which is transferred from a first functional or constructional unit of a plant into a second functional or structural unit. In the context of this application, for example, such a collecting stream is transferred from an air treatment unit into a power plant unit. A collecting stream can be routed in one or more lines. A "formation" of a corresponding collective stream is therefore its provision by the first functional or structural unit to the second functional or structural unit. The two or more streams will be there especially in a common direction. However, this need not necessarily be done, a collecting stream, as mentioned, are also performed in two or more lines.

Advantages of the invention

The present invention is based on a previously explained method for generating electrical energy in a combined power generation plant comprising an air treatment unit and a power plant unit.

In the method, in a first operating mode, the already mentioned liquefaction operation, a first warm compressed air flow in a heat exchanger system is cooled to a first cold compressed air flow. From the first cold compressed air stream, a first cryogenic liquid stream of an air liquefaction product is produced, which is stored in a tank system. As mentioned, the first cryogenic liquid stream is liquefied air or another air fraction, such as liquid nitrogen or a nitrogen-enriched fraction. Preferably, however, the cryogenic liquid stream contains significantly less than 40 mole percent oxygen. An appropriately stored cryogenic air liquefaction product thus forms a storage medium which is produced in low-flow times or excess-current periods and can be kept available for high-current cycle times.

In a second mode of operation, the aforementioned removal operation, which is typically performed during the high-current cycle times, on the other hand, a second warm compressed air stream in the heat exchanger system is cooled to a second cold compressed air stream, the second cold compressed air stream being compressed in a cold compressor system to a first high pressure stream. Preferably, only exactly one cold compressor system is used in the context of the present invention. Further preferably, the second cold compressed air stream is fed to the cold compressor system at the lowest temperature level which can be provided by the heat exchanger system, in particular at -140 to -180 ° C., for example at -150 to -170 ° C.

The first compressed air flow of the first mode of operation is provided by compression in a main compressor system and repressurization in a post-compressor system. Both the main and the Nachverdichtersystem can thereby comprise a plurality of compressor stages, which, as already explained above, are driven by a common compressor drive via a common shaft. The main compressor system and the Nachverdichtersystem can also have means for intermediate and post-cooling. Furthermore, in the first operating mode, a compressed-air flow downstream of the after-compressor system can be increased again by a booster turbine. The correspondingly compressed first compressed air flow can also be at least partially expanded in an expansion turbine integrated in the heat exchanger system, which can be coupled to a generator, for example, whereby cold can be generated for operation of the heat exchanger system.

The second warm compressed air flow of the second operating mode, however, is preferably compressed only by compression in the main compressor system. It is thus preferably provided at a lower pressure level than the first compressed air flow and fed into the heat exchanger system.

The upstream and downstream of the main compressor system, the post-compressor system, the booster turbine, an expansion turbine in a liquefaction system and the cold compressor system typically present hereinbelow will be further explained with reference to the accompanying drawings.

The first and second warm compressed air streams are respectively cooled to the first and second cold compressed air streams, wherein equal or different temperature levels can be generated by removing the first and second cold compressed air streams from the heat exchanger system at different locations. Preferably, the first and the second warm compressed air stream in the heat exchanger system, which may in particular comprise two heat exchanger blocks, passed through different passages. The first and the second warm compressed air stream can each be provided in different volume flows.

The first warm compressed air flow of the first mode of operation is diverted from a main stream that has been compressed in the main and in the Nachverdichtersystem. A remaining flow is also cooled in the heat exchanger system or in a part of this heat exchanger system, for example a first heat exchanger block. The correspondingly cooled residual flow is subsequently expanded in an expansion turbine, which is part of the previously explained booster turbine, by means of which the first warm compressed air flow is provided. As a result, the cooling required for Luftverflüsigung is generated and uses the released mechanical power. The residual stream which has been relieved in the booster turbine can then preferably be warmed up in the heat exchanger system and, for example, fed again to the after-compressor system. Details of this are shown in the attached figures and will be explained in more detail with reference to these.

In the second operating mode, a second cryogenic liquid stream is also removed from the tank system, pressure-increased by means of a pump and heated in the heat exchanger system and thus converted into a gaseous or supercritical state, ie vaporized or pseudo-vaporized to a second high pressure stream. The second high-pressure stream is combined with the first high-pressure stream, which, as explained above, is obtained from the second cold compressed air stream by means of the cold-compressor system, to form a collecting stream. The collecting stream, which is present at a pressure level of in particular 12 bar or more, or a stream derived from the collecting stream, is expanded in at least one expansion turbine coupled to a generator of the illustrated power plant unit. As explained, a "collecting stream" can also be conducted at several pressure levels in different lines.

In the method according to the invention, the volume flow of the collecting stream advantageously comprises at most 110% of the combined volume flows of the first and second high-pressure streams. In particular, the collecting stream is formed exclusively from the first and the second high-pressure stream, which does not preclude, however, diverting partial streams from the first and / or the second high-pressure stream before combining them with the collecting stream and being able to be fed again to the respective streams. These can be used, for example, for the regeneration of a cleaning system or adsorbent container used herein. It follows that no further streams are combined to form the collecting stream. This means that advantageously only a single second compressed air flow generated with a cold compressor system is used or only a single cold compressor system is used in the system according to the invention. In other words, the cold compressor system used to compress the second cold compressed air stream is advantageously the only cold compressor system used in the power plant. It should be noted that a cold compressor system is powered by means of a drive powered by external energy, such as an electric motor, and thereby different from a booster turbine.

Since the first and second cryogenic liquid streams are stored in and removed from the same tank system, the first and second cryogenic liquid streams i.d.R. an identical composition, ie consist of the same air liquefaction product. In this connection, it should be emphasized that in the first operating mode, preferably only the first warm and the first cold compressed air flow are provided and that in the second operating mode, preferably only the second hot and the second cold compressed air flow are provided. Corresponding streams may, unless otherwise indicated, each have an identical composition and / or identical temperature levels and / or be conducted in the same lines. Therefore, a distinction between "first" and "second" hot and cold compressed air streams is therefore partially made to identify differences between the first and second modes of operation.

In the method according to the invention, therefore, in the second operating mode, the evaporation or pseudo-vaporization of the second cryogenic liquid stream is carried out in the heat exchanger system of the air treatment unit. This means that during the second mode of operation, the cryogenic liquid stream is not introduced into a separate heat exchanger and evaporated or pseudo-vaporized, for example against atmospheric air or hot (water) steam, but this step is performed in the heat exchanger system of the air treatment unit, anyway the cooling of the first warm compressed air flow in the first operating mode is present. At first glance, this seems unfavorable, because it no longer makes inexpensive heating media such as the atmosphere or steam but a heating medium compatible with the air handling unit needs to be generated and fed into the heat exchanger system to provide the heat needed for the vaporization or pseudo-vaporization. However, it has been found that this results in a total economically advantageous system.

It is favorable if feed air in the form of the second warm compressed air flow in the heat exchanger system is also cooled in the second operating mode. Thus, a required for the evaporation of the second cryogenic liquid flow heating medium is generated using the existing air treatment unit and this does not have to be turned off.

It also initially appears unfavorable, in the second operating mode in which the energy price is high, to continue operating the air treatment unit and in particular a corresponding main compressor system. However, it has also been found here that this high operational advantages are connected, because the main compressor system when switching between the operating modes does not have to be switched off and on, but can continue to run continuously. In addition, from the second warm compressed air stream obtained here, as explained, the first high-pressure stream can be obtained in an especially energy-efficient manner, since the compaction generally requires less energy at low temperatures. Therefore, in this way, additional electrical energy can be obtained very favorably from the first high-pressure current.

According to the invention, in the first operating mode in the heat exchanger system, the first hot compressed air stream, mentioned several times, is cooled at least partially against a flow of a liquid refrigerant, and the second low-temperature liquid stream in the second operating mode in the heat exchanger system partly against a flow of liquid Is heated refrigerant.

In another part of the first warm compressed air flow in the first operating mode in the heat exchanger system against a relaxed and cooled compressed air stream, namely the above-mentioned residual flow, cooled. Of the second cryogenic liquid stream, however, is heated in the second mode of operation in the heat exchanger system to another part against the second warm compressed air stream.

With appropriate refrigerants, the heat exchange diagram of a heat exchanger system used can be made particularly favorable. As a liquid refrigerant in particular methanol (range up to -95 ° C) is used. A liquid refrigerant for use in the invention is particularly selected based on its boiling point. This must be selected so that the liquid refrigerant is liquid in the entire work area. Suitable for this purpose, as mentioned, in particular methanol, but also ethanol. In addition to methanol and ethanol, the nidederwertigen alcohols listed in the following table can also be used as a refrigerant in the present invention. Surname Melting point in ° C Boiling temperature in ° C methanol -97.8 64.7 ethanol -114.1 78.3 Propane-1-ol -126.2 97.2 Butane-1-ol -89.3 117.3 Pentane-1-ol -78.2 138 Hexan-1-ol -48.6 157.5 Propane-2-ol -88.5 82.3 Butane-2-ol -114.7 99.5 2-methyl propane-1-ol -108 108 Pentane-2-ol -50 118.9 2-methylbutane-1-ol -70 129 3-methyl-1-ol -117 130.8 1,2-propanediol -68 188 Butane-1,2-diol -114 192 Butane-1,3-diol below -50 207.5 Prop-2-en-1-ol -129 97 Pentane-1-ol -78.2 128.0

Of course, one or more further liquid, possibly organic, refrigerants can be used in the invention. As a result, the heat exchange can be further optimized; However, the apparatus and control engineering effort is higher. The liquid or the liquid refrigerant are guided in corresponding heat exchanger sections or heat exchanger blocks of the heat exchanger system and stored in suitable cold-insulated refrigerant tanks.

In the method according to the invention, the respective flow of liquid refrigerant in the first operating mode is advantageously taken from a first coolant tank, heated in the heat exchanger system and transferred to a second coolant tank. In the second mode of operation, the flow of liquid refrigerant is taken from the second refrigerant tank, cooled in the heat exchanger system, and transferred to the first refrigerant tank.

Furthermore, a non-condensing gas, for example nitrogen, superimposed on the liquid refrigerant in the first and second refrigerant tanks is advantageously used here. This is taken from the first refrigerant tank in the first operating mode, cooled in the heat exchanger system and transferred to the second refrigerant tank. In the second mode of operation, the illustrated flow of non-condensing gas is taken from the second refrigerant tank, heated in the heat exchanger system, and transferred to the first refrigerant tank. As a result, a completely self-sufficient, reversible cooling possibility for the currents described above is created on the whole, which does not rely on the supply of external refrigerants and is capable of reversibly storing the respective supplied or discharged cold.

As an alternative to the use of the liquid refrigerant proposed according to the invention, further cooling for cooling the first warm compressed air flow to the first cold compressed air flow in the first operating mode could also be provided by relaxation of further compressed air. However, this would have to be provided in a larger amount, which requires additional energy. At the same time, the released during the relaxation of such additional compressed air mechanical performance can be recovered only insufficient. A corresponding process is thus highly irreversible.

Correspondingly, the cold (thermal energy) resulting from the evaporation or pseudo-vaporization of the second cryogenic liquid stream in the second operating mode could also be converted into mechanical energy (compressed air energy) by means of an additional cold compressor system. However, this process is also highly irreversible, causing thermodynamic losses and has a negative effect on the efficiency of a corresponding system.

It is therefore desirable to limit such highly irreversible processes and replace them with less irreversible processes. This is made possible by the use of the liquid refrigerant.

The method according to the invention proves to be particularly advantageous over likewise fundamentally possible methods, in which the provision of the currents relaxed in the power unit takes place by means of at least two parallel-connected cold compressor systems. The at least two cold compressor systems can have the same or different inlet temperature. Although such methods can be carried out in a relatively efficient manner and the amount of additional air can be flexibly adapted to the current needs. However, it has been found that the use of only a single cold compressor system together with the use of the liquid refrigerant operational advantages, in particular a 3 to 5% increased efficiency results.

In a first variant of the method according to the invention, in the second operating mode, at least part of the generation of electrical energy from the collecting stream is carried out in an expansion turbine of a gas turbine of the power station unit. The expansion turbine of the gas turbine is supplied with a current derived from the collecting stream. For this purpose, the collecting stream is introduced into a combustion chamber of the gas turbine into which a fuel, for example natural gas, biogas or the like, is simultaneously introduced. The fuel is burned in the combustion chamber in an atmosphere created at least in part by the collection stream. Of course, the combustion chamber, however, also other streams, such as an oxygen-rich stream, are supplied.

The expansion turbine of the gas turbine is thus supplied with a fluid derived from the collecting stream (by the admission of the exhaust gas of the combustion in the combustion chamber and the partial conversion of the oxygen possibly contained in the collecting stream). By the exhaust gas combustion in the combustion chamber, the volume is further increased. Typically, only part of the collected stream, for example 4 to 5%, is chemically reacted in the combustion chamber with the fuel by combustion, i. The fuel is reacted in the combustion chamber with a significantly more than stoichiometric amount of the collecting stream or the oxygen contained therein.

At least part of the generation of mechanical energy from the collecting stream or a stream derived therefrom is carried out in this variant in the gas turbine of the power plant unit, ie in an apparatus already present in the power plant unit for converting pressure energy into mechanical drive energy. An additional separate system for work-performing expansion of the collecting stream or a stream derived therefrom can be less complicated in the context of the invention or omitted altogether. In the simplest case, in the invention, the entire generation of mechanical or electrical energy from the collecting stream or a current derived therefrom in the gas turbine can be made.

In a second variant, the expansion turbine in which the collecting fluid or the fluid derived therefrom is expanded, part of a hot gas turbine, which comprises at least one heater in addition to the expansion turbine. The heater is operated in particular by means of solar heat and / or waste heat from other processes, so that the process is particularly economical.

The two variants mentioned can also be combined by using a power station unit with both one or more hot gas turbines and with one or more gas turbines. In this case, the collecting stream or a stream derived therefrom, for example, relaxed in two steps, the first step as work-performing relaxation in the hot gas turbine (after previous heating in a heater) and the second step as work-related relaxation in the gas turbine (after passing through the combustion chamber) performed become. The collecting stream is in particular in the hot gas turbine of a Hot gas turbine inlet pressure relaxed on a hot gas turbine outlet pressure. The hot gas turbine outlet pressure increases again in the downstream combustion chamber of the gas turbine, so that a corresponding flow is again pressure-increased fed to the expansion turbine of the gas turbine.

To reduce or symmetrize an axle load of a generator used in the invention, this may also be formed with an axle or shaft which is equipped with expansion turbines arranged on both sides of the generator. By such a symmetrical arrangement, a one-sided stress of a generator is reduced. It is particularly advantageous to divide the collecting stream or the stream derived therefrom, for example upstream or downstream of a heater and / or a combustion chamber, into two or more substreams, each of which is expanded in a relaxation machine coupled to a common generator.

A corresponding expansion turbine can also be followed by other plants or facilities for the recovery of energy. For example, at least one waste heat steam generator can be provided. By means of the waste heat steam generator, which may for example be connected downstream of a gas turbine or hot gas turbine, residual heat can be used from an exhaust gas stream obtained there to generate steam. The steam can in turn be used to operate a generator.

In the context of the present invention may finally be provided to store or feed the cryogenic, liquefied stream into the tank system under superatmospheric pressure, for example at a pressure level of 8 to 12 bar or at atmospheric pressure. Storage at superatmospheric pressure makes it possible to dispense with subcooling of a corresponding flow, which reduces the refrigeration requirement and thus the amount of air required in the system.

The power generating plant also provided according to the invention benefits from the advantages explained above, to which reference is expressly made. This has in particular a control device which at least accomplishes the automatic control of the power generation plant during the first operating mode and during the second operating mode.

The invention will be explained in more detail below with reference to the accompanying drawings which show, inter alia, preferred embodiments of the invention in different operating modes.

Figur 1A

zeigt eine Energieerzeugungsanlage gemäß einer Ausführungsform der Erfindung in einem ersten Betriebsmodus.

Figur 1 B

zeigt die Energieerzeugungsanlage der Figur 1A in einem zweiten Betriebsmodus.

Figur 2A

zeigt eine Energieerzeugungsanlage gemäß einer Ausführungsform der Erfindung in dem ersten Betriebsmodus.

Figur 2B

zeigt die Energieerzeugungsanlage der Figur 2A in dem zweiten Betriebsmodus.

Figur 3A

zeigt ein Speichersystem gemäß einer Ausführungsform der Erfindung in dem ersten Betriebsmodus.

Figur 3B

zeigt das Speichersystem der Figur 3A in dem zweiten Betriebsmodus.

Figur 4

zeigt eine Kraftwerkseinheit gemäß einer Ausführungsform der Erfindung.

Figur 5

zeigt eine Kraftwerkseinheit gemäß einer Ausführungsform der Erfindung.

Figur 6

zeigt eine Kraftwerkseinheit gemäß einer Ausführungsform der Erfindung.

Figur 7

zeigt eine Kraftwerkseinheit gemäß einer Ausführungsform der Erfindung.

Figur 8

zeigt eine Kraftwerkseinheit gemäß einer Ausführungsform der Erfindung.

Brief description of the drawings

Figure 1A

shows a power plant according to an embodiment of the invention in a first mode of operation.

Figure 1 B

shows the power plant of the Figure 1A in a second mode of operation.

FIG. 2A

shows a power plant according to an embodiment of the invention in the first mode of operation.

FIG. 2B

shows the power plant of the FIG. 2A in the second mode of operation.

FIG. 3A

shows a storage system according to an embodiment of the invention in the first mode of operation.

FIG. 3B

Figure 3 shows the memory system of Figure 3A in the second mode of operation.

FIG. 4

shows a power plant unit according to an embodiment of the invention.

FIG. 5

shows a power plant unit according to an embodiment of the invention.

FIG. 6

shows a power plant unit according to an embodiment of the invention.

FIG. 7

shows a power plant unit according to an embodiment of the invention.

FIG. 8

shows a power plant unit according to an embodiment of the invention.

Detailed description of the drawings

In the figures, corresponding elements carry identical reference numerals. A repeated explanation is omitted for clarity. All figures show plant diagrams of power generation plants or their parts in a highly simplified, schematic representation. Here are partially different modes of operation (see. Figure 1A . 2A and 3A opposite Figure 1 B . 2B and 3B ) compared to each other. These operating modes differ, inter alia, in the circuit of a plurality of valves provided in a corresponding system. The valves are not shown in detail. This applies in particular to conductive (permeable) switched valves. However, lines blocked by corresponding valves or inactive currents are shown crossed (-x-).

Figure 1A shows a power plant according to an embodiment of the invention in a first mode of operation. The power generation plant is designated 100 in total. It has components of an air handling unit, dashed and total of 10, and components of a power plant unit, which are dashed and total 20. The Indian Figure 1A shown first operating mode of the power generation plant 100 corresponds to the previously explained in more detail liquefaction operation.

By means of a main compressor system 11 of the air treatment unit 10, which may be preceded by an air filter 111, ambient air AIR is sucked in and compressed. The main compressor system 11 may comprise a plurality of compressor stages (here without a separate designation) as well as means for intermediate and after-cooling. The compressor stages of the main compressor system 11 can be driven by a common compressor drive M. For aftercooling it is also possible, for example, to provide a heat exchanger 112 which can be operated with a stream taken downstream in the air treatment unit 10 (see links 1 and 2).

A stream a provided by the main compressor system 11 may be supplied to a purification system 12 having suitable means for purifying the flow a, for example a pair of adsorbent vessels 121 and 122 filled, for example, with molecular sieve. The latter can be used in alternating operation for the purification and regenerated, including suitable switching means (not illustrated in detail) are provided. For the regeneration of the adsorber vessels 121 and 122, streams can be used which are taken downstream in the air treatment unit 10 (see links 3 and 4). A correspondingly purified stream b can then be fed to a post-compressor system 13 of the air treatment unit 10. The secondary compressor system 13, like the main compressor system 11, can have a plurality of compressor stages (not designated in any more detail) with means for intermediate and after-cooling and can be driven by means of a common compressor drive M. A current c thus obtained can be further increased in pressure in a compressor stage 141 of a booster turbine 14. The compressor stage 141 of the booster turbine 14 is mechanically coupled to an expansion turbine 142 which may be driven by means of an expanding stream diverted downstream from the stream d (see below).

A further pressure d in the booster turbine 14 can be fed into a heat exchanger system 15 of the air treatment unit. In the illustrated example, the heat exchanger system 15 of the air treatment unit 10 has a first heat exchanger block 151 and a second heat exchanger block 152. Before feeding into the heat exchanger system 15, the stream d is split into a first substream e and a second substream f. Both partial flows are supplied to the first heat exchanger block 151 of the heat exchanger system 15 at its warm end.

The first partial flow e passes through the first heat exchanger block 151 of the heat exchanger system 15 up to its cold end. He is then relaxed in the expansion turbine 142 of the previously explained Boosterturbine 14. After expansion, this stream is fed to the cold end of the second heat exchanger block 152 of the heat exchanger system 15 and heated there. After further heating in the first heat exchanger block 151 of the heat exchanger system 15, the correspondingly obtained warm stream is fed again to the after-compressor system 13.

The second partial flow f (the previously mentioned "first warm compressed air flow") passes through the first heat exchanger block 151 of the heat exchanger system 15 almost to its cold end and is taken there as stream g. After a further cooling in the second heat exchanger block 152 of the heat exchanger system 15, this is present as stream h (the "first cold compressed air stream"). The stream h is then liquefied and subcooled in a liquefaction system 16 comprising a braked turbine 161, a separator 162 and a subcooler 163. The subcooler 163 may also be operated with a partial flow j of a cryogenic liquid stream i obtained by the liquefaction. The stream j is warmed in the heat exchanger system 15 and discharged to the amb environment. The deep-drawn liquid stream i withdrawn from the sump of the separator 162 is fed into a tank system 17 as a cryogenic air liquefaction product. The cryogenic air liquefaction product is also referred to as LAIR and represents liquefied air in the example shown. As explained in more detail, liquid nitrogen products, impure nitrogen and the like can also be used as air liquefaction products.

The cooling of the corresponding streams in the first heat exchanger block of the heat exchanger system 17 takes place at least in part by means of expansion cooling, which is generated by the expansion turbine 142. Further cold is provided in the context of the present invention by means of a refrigerant system 18. The refrigerant system 18 shown in FIGS. 3A and 3B 3B is illustrated in detail, has at least two refrigerant tanks and is adapted to be used in the Figure 1A illustrated first mode of operation to conduct a cooled liquid refrigerant as stream k from the cold end to the warm end through the heat exchanger block 151 of the heat exchanger system 15. The cooled liquid refrigerant is thus heated against a stream e or f to be cooled in the first heat exchanger block 151 of the heat exchanger system 15. In contrast to the theoretically also possible use of a further expansion turbine for generating cold, the use of the refrigerant system 18 allows the reversible supply of cold to the streams passing through the first heat exchanger block 151 of the heat exchanger system 15.

The power plant unit 20 is in the in Figure 1A The first operating mode shown is not in operation or is fed exclusively by means of a fuel F. The power plant unit 20 will therefore be described with reference to the following FIG. 1 B explained in more detail.

The FIG. 1B shows the power generation plant 100, which is also in Figure 1A is shown in the multiply explained second operating mode, the removal operation.

The stream b likewise provided in the removal operation is not recompressed in the after-compressor system 13 in the second operating mode. In the illustrated example, this stream b (the "second warm compressed air stream") is completely cooled in the first heat exchanger block 151 and the second heat exchanger block 152 of the heat exchanger system 15. A cold compressed air flow m obtained thereby (the "second cold compressed air flow") is then compressed in a multi-stage cold compressor 19, the compressor stages of which can in turn be driven by means of a common compressor drive M. A partially heated and compressed stream n obtained by the heat of compression and the compressor capacity of the cold compressor 19 is further heated in the first heat exchanger block 151 of the heat exchanger system 15 and leaves it as a warm high pressure stream o ("first high pressure stream").

Further, in the second mode of operation, the cryogenic air liquefaction product LAIR fed into the first operating mode from the tank system 17 is taken as stream p (the "cryogenic liquid stream"), liquid pressure increased by a pump 171, and stream q at superatmospheric pressure in the tank Heat exchanger system 15 is converted into a gaseous or supercritical state. For this purpose, the stream q is first supplied to the second heat exchanger block 152 of the heat exchanger system 15 and taken almost at its warm end. The withdrawn stream is then passed through the first heat exchanger block 151 of the heat exchanger system 15 and expanded in an expansion turbine 152, which may be coupled to a generator G. As a result, additional energy and cold can be gained. The correspondingly relaxed stream, which has undergone renewed cooling due to the expansion, is fed again near its cold end to the first heat exchanger block 151 of the heat exchanger system 15. It leaves the first heat exchanger block 151 of the heat exchanger system 15 as a warm high pressure stream s ("second high pressure stream"). The first high-pressure stream o and the second high-pressure stream s are combined to form a collecting stream t and discharged from the air treatment unit 10. The collecting stream t is introduced into the power plant unit 20.

In the power plant unit 20, the collecting stream t first passes through a heat exchanger 21. Subsequently, the collecting stream t is passed through a combustion chamber 22, in which a suitable fuel F, for example natural gas, is burned. By the formed exhaust gas, the volume of the collecting stream t increases, and it is obtained from the collecting stream derived current u. This is supplied to an expansion turbine 23, which may be formed for example as part of a gas turbine and is coupled to a generator G. The mechanical power dissipated by the relaxation of the current u derived from the collecting current t can thus be converted into electrical energy. The heat exchanger 21, which is used for further heating of the collecting stream t, can be operated by means of an exhaust gas v from the expansion turbine 23. Regenerating gas can also be heated for regeneration in the cleaning unit 12 by means of the heat exchanger 21 (cf., link 1 to stream s, links 1 and 2 in the heat exchanger 112, links 2 and 3 in the heat exchanger 21, links 3 and 4 in the cleaning system 12 , Link 4 to stream t).

The power generation plant 100 of Figures 1A and 1 B or their air treatment unit 10 and thus the tank system 17 are set up for storage of the cryogenic air liquefaction product LAIR at atmospheric pressure. The FIGS. 2A and 2 B on the other hand show a power generation plant 200 according to another embodiment of the invention, in which the air treatment unit 10 and the tank system 17 are arranged for a pressure storage of the cryogenic air liquefaction product LAIR. In the FIGS. 2A and 2 B a corresponding power generation plant 200 is shown again in the already explained operating modes (liquefaction operation and removal operation). The operation of the system is not explained repeatedly.

The energy generation plant 200 or its air treatment unit 10 differs from the energy generation plant 100 or its air treatment unit 10 in particular by the absence of the heat exchanger or subcooler 163, which is operated with the current j. Due to the pressure storage of the cryogenic air liquefaction product LAIR in the tank system 17, a corresponding system can therefore be operated more efficiently, because no portion of the cryogenic air liquefaction product LAIR (cf flow j in FIG Figure 1A ) must be used for the subcooling in the heat exchanger 163.

The in the FIGS. 1A to 2B shown currents can be present in particular at the following pressure levels: Stream a, b 3 to 8 bar, in particular 4 to 6 bar Electricity c 30 to 100 bar, in particular 30 to 50 bar Stream d, e, f 45 to 100 bar, in particular 50 to 70 bar Electricity i 1 to 8 bar, in particular 1 to 6 bar Stream n, o, s, t, u 10 to 40 bar, in particular 12 to 20 bar Electricity q 30 to 100 bar, in particular 40 to 80 bar Electricity v Atmospheric pressure or 1 to 1.2 bar

Figures 3A and 3B show a refrigerant system 18, which in its basic. Function has already been explained above, in the previously explained operating modes (first operating mode or liquefaction operation in Figure 3A, second operating mode or removal operation, in FIG. 3B ). The already partially explained currents I and k are in the figures 3A and 3B shown again. Furthermore, FIGS. 3A and 3B show 3B the first heat exchanger block 151 of the heat exchanger system 15, which has already been explained above in its integration into corresponding power generation plants 100 and 200 or their air treatment units 10.

In the highly simplified representation here, the first heat exchanger block 151 of the heat exchanger system 15 is flowed through here only by a current e or f (liquefaction operation) and o or s (removal operation). In the first operating mode (FIG. 3A, liquefaction operation), cold is transferred from a liquid refrigerant to the flows e or f; in the second operating mode, cold is transferred from the cold flows o or s to the liquid refrigerant. The designation of the currents k and I corresponds to that of the FIGS. 1A to 2B ,

The refrigerant system 18 comprises a first refrigerant tank 181 and a second refrigerant tank 182, in each of which the liquid refrigerant is superimposed by a gaseous, non-condensing medium, for example gaseous nitrogen. The gaseous nitrogen forms the current I, the liquid refrigerant the current k. In the first operating mode (FIG. 3A), the liquid refrigerant from the second refrigerant tank 182 is pumped by means of a pump 183 from the cold end to the warm one End passed through the first heat exchanger block 151 of the heat exchanger system 15 as a current k. The current k can thereby heat up. It is then transferred into the first refrigerant tank 181 and displaces there the gaseous medium, which is guided as current I against the current k through the first heat exchanger block 151 of the heat exchanger system 15. Operation in the second operating mode (removal operation, FIG. 3B ) takes place in the opposite way and results directly from the FIG. 3B ,

In the FIGS. 4 to 8 different embodiments of the power plant unit 20 are shown, which can be used alternatively or optionally in combination in the context of the present invention. Already explained elements are not discussed again for clarity.

In the in FIG. 4 illustrated embodiment of the power plant unit 20, in all FIGS. 4 to 8 can be realized as so-called "Power Island" is, as already explained above, a combustion chamber 22 is present. A heat exchanger 21 is not shown in the example shown, but can also be realized here. To use the residual heat from the expansion turbine 23, a waste heat steam generator 24 is additionally provided here. In this way, by means of the generator G, which is coupled to the expansion turbine 23, a first power component P1, and via the waste heat steam generator 24, a second power component P2 can be obtained. The waste heat steam generator 24 is configured, for example, to generate high-pressure steam, which can be used in a downstream turbine and / or in other system components.

In the FIG. 5 illustrated embodiment of the power plant unit 20 differs from that in the FIGS. 1A to 2B shown embodiments, characterized in that instead of the combustion chamber 22, a supplied with externally supplied heat Q1 heater 25 is provided. This can represent, for example, waste heat of another process, heat from a heat storage system and / or heat from a solar system. By providing the heater 25 instead of the combustion chamber 22, a particularly resource-saving operation of a corresponding system can be realized.

In the FIGS. 6 to 8 Power plant units 20 are shown, which allow a reduction of an axle load on a generator G. The elements used in this case have already been explained predominantly. The reduction of the axle load on the generator G results essentially by the provision of paired components. For example, in the in FIG. 6 illustrated embodiment, the combustion chamber 22 easily available. However, a stream from the combustion chamber 22 is divided downstream of the combustion chamber 22 into two sub-streams (without designation), which are separately fed into each one expansion turbine 23 a and 23 b and relaxed in this. By means of the generator G, the common mechanical power of the expansion turbines 23a and 23b can thus be set into electrical power P.

Also in the in FIGS. 7 and 8 illustrated embodiments, two expansion turbines 23a and 23b are provided in each case. In FIG. 7 In addition, two separate combustion chambers 22a and 22b are present, which in FIG. 8 embodiment shown further comprises two separate heat exchanger blocks 21 a and 21 b. Due to the symmetrical arrangement of the expansion turbines 23a and 23b in the previously explained FIGS. 6 to 8 the axle load is transmitted symmetrically to the generator G.

Claims (14)

Method for generating electrical energy in a combined power generation plant (100, 200) comprising an air treatment unit (10) and a power plant unit (20), In a first operating mode (liquefaction operation): a first warm compressed air flow (f) in a heat exchanger system (15) of the air treatment unit (10) is cooled to a first cold compressed air flow (h), wherein a first cryogenic liquid flow (i) is produced from the first cold compressed air flow (h) and a tank system (17) is transferred to the air treatment unit (10), And in a second operating mode (unloading operation): - a second warm compressed air stream (b) is cooled in the heat exchanger system (15) to a second cold compressed air stream (m), wherein the second cold compressed air stream (m) in a cold compressor system (16) of the air treatment unit (10) to a first high pressure stream (n ) is compressed a second cryogenic liquid stream (p) is taken from the tank system (17) and vaporized or pseudo evaporated in the heat exchanger system (15) to a second high pressure stream (s), wherein from the first (n) and second high pressure streams (s) Aggregate flow (t) is formed, and the collecting stream (t) or a stream (u) derived therefrom is expanded in at least one expansion turbine (23) of the power station unit (20) coupled to a generator (G),
characterized, That the first warm compressed air flow (f) in the first operating mode in the heat exchanger system (15) is cooled at least in part against a flow (k) of a liquid refrigerant, and • that the second cryogenic liquid stream (p) in the second operating mode in the heat exchanger system (15) is at least partially heated against a flow (k) of the liquid refrigerant. The method of claim 1, wherein the liquid refrigerant comprises at least one lower alcohol and / or one liquefied alkane. The method of claim 1 or 2, wherein the flow (k) of the liquid refrigerant Taken in the first operating mode from a first refrigerant tank (181), is heated in the heat exchanger system (15) and transferred to a second refrigerant tank (181), and Is removed from the second refrigerant tank (182) in the second operating mode, cooled in the heat exchanger system (15), and transferred to the first refrigerant tank (181). The method of claim 3, wherein a stream (I) of a non-condensing gas overlying the liquid refrigerant in the first (181) and second refrigerant tanks (182) In the first operating mode, taken from the first refrigerant tank (181), cooled in the heat exchanger system (15) and transferred to the second refrigerant tank (181), and Is removed from the second refrigerant tank (182) in the second operating mode, heated in the heat exchanger system (15), and transferred to the first refrigerant tank (181). Method according to one of the preceding claims, in which the mass flow of the collecting stream (t) corresponds to at most 110 percent of the combined mass flows of the first (n) and the second high-pressure stream (s). A method according to any one of the preceding claims, wherein the cold compressor system (16) used to compress the second cold compressed air stream (m) is the only cold compressor system used in the power plant (100, 200). Method according to one of the preceding claims, in which a current (u) derived from the collecting stream (t) is expanded in the at least one expansion turbine (23) of the power station unit (20) coupled to the generator (G), t) derived current (u) is formed by burning a fuel (F) in a gas at least formed by the collecting stream (t) gas atmosphere. Method according to one of the preceding claims, in which the collecting stream (t) or a stream (u) derived therefrom is heated prior to its expansion in the at least one expansion turbine (23) of the power station unit (20) coupled to the generator (G). Method according to one of the preceding claims, in which waste heat of the collecting stream (t) or of the stream (u) derived therefrom, after its expansion in the at least one expansion turbine (23) coupled to the generator (G), is used to generate steam. Method according to one of the preceding claims, in which the collecting stream (t) or the stream (u) derived therefrom is divided into two sub-streams, each of which is expanded in an expansion turbine (23a, 23b) coupled to a common generator (G). A power generation plant (100, 200) for generating electrical energy comprising an air handling unit (10) combined with a power plant unit (20) and adapted to • in a first operating mode (liquefaction mode): to cool a first hot compressed air stream (f) by means of a heat exchanger system (15) of the air treatment unit (10) to a first cold compressed air stream (h), from this by means of a liquefaction system (16) of the air treatment unit (10) a first cryogenic liquid stream (i) and to transfer the first cryogenic liquid stream (i) into a tank system (17) of the air treatment unit (10), • and in a second operating mode (unloading operation): to cool a second hot compressed air stream (b) by means of the heat exchanger system (15) to a second cold compressed air stream (m) and to compact it by means of a cold compressor system (16) of the air treatment unit (10) into a first high pressure stream (n), - To remove a second cryogenic liquid stream (p) from the tank system (17) and this by means of the heat exchanger system (15) to a evaporating or pseudo-evaporating the second high-pressure stream (s) and forming a collecting stream (t) from the first and second high-pressure streams (s), and to relax the collecting stream (t) or a stream (u) derived therefrom in at least one expansion turbine (23) of the power station unit (20) coupled to a generator (G), characterized
that a refrigerant system (18) is provided, which is set up To cool the first warm compressed air flow (f) in the first operating mode in the heat exchanger system (15) at least partially against a flow (k) of a liquid refrigerant, and • heat the cryogenic liquid stream (p) in the second operating mode in the heat exchanger system (15) at least in part against a flow (k) of the liquid refrigerant. A power plant (100, 200) according to claim 11, comprising a control system adapted to switch from the first to the second operating mode depending on a level of the liquid reservoir (17), a time of day and / or an external request. A power plant (100, 200) according to claim 11 or 12, comprising a refrigerant system (18) having first (181) and second refrigerant reservoirs (182) and configured to control the flow (k) of the liquid refrigerant • In the first operating mode to remove the first refrigerant storage (181), in the heat exchanger system (15) to heat and transfer to the second refrigerant storage (181), and • In the second operating mode to remove the second refrigerant storage (182), to cool in the heat exchanger system (15) and to transfer in the first refrigerant storage (181). A power plant (100, 200) according to any one of claims 11 to 13, comprising exactly one cold compressor system (16).

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