Charging and discharging of a thermal energy storage system with integrated gas separation

Abstract

The invention relates to a method for charging and / or discharging a thermal energy storage system (12) by means of a gas mixture stream (14) comprising a gas component (16) and for separating the gas component (16) from the gas mixture stream (14), comprising: compressing the gas mixture stream (14); charging and / or discharging a high-temperature heat storage device (28) by means of the gas mixture stream (14); expanding the gas mixture stream (14); charging and / or discharging a low-temperature cold storage device (32) by means of the gas mixture stream (14); wherein the gas component (16) is separated from the gas mixture stream (14) before or after the charging and / or discharging of the high-temperature heat storage device (28) and / or before or after the charging and / or discharging of the low-temperature cold storage device (32).

Description

[0001] The invention relates to the field of thermal storage systems and the separation of gas components from a gas mixture stream. The invention relates to a method and a device for charging and / or discharging at least one thermal energy storage device and for separating at least one gas component from a gas mixture stream.

[0002] Renewable energy sources (e.g., solar, wind, and hydropower) are inherently characterized by highly fluctuating power generation profiles. For a high share of renewable energy in electricity generation, especially at shares exceeding 50%, compensation measures are necessary to balance fluctuations both within a single day and over several days.

[0003] One approach is the use of large-scale energy storage systems (e.g., batteries, pumped-storage hydroelectric plants) with capacities ranging from 1 MWh to over 1 GWh. However, currently available storage technologies are reaching their limits in terms of scalability, cost, lifespan, and geographical and topographical requirements.

[0004] An alternative approach is to operate thermal power plants (e.g., using fossil fuels, hydrogen, synthetic natural gas (SNG), biomass, or biomethane) flexibly to compensate for fluctuations. However, this approach requires costly retrofitting or new construction and generally leads to additional carbon dioxide (CO2) emissions.

[0005] At the same time, the use of fossil fuels, SNG, or biomass / biomethane in electricity generation and energy-intensive industrial processes (e.g., cement production) causes significant amounts of carbon dioxide. Reducing CO2 emissions is a key element in limiting global warming.

[0006] Although CCU / CCS technologies (CCU: Carbon Capture and Utilization, CCS: Carbon Capture and Storage) represent possible means of CO2 capture, they often have high energy demands, complex integration requirements, and significant investment and operating costs.

[0007] Increasing the thermal efficiency of power plants can also contribute to reducing emissions, although the efficiency gains achievable in practice, especially in modern thermal power plants in most industrialized nations, are usually limited.

[0008] Currently, technical concepts and solutions exist that each address only a part of the aforementioned problems – either the short-term compensation of fluctuations in renewable energy or electricity generation, or the reduction or capture of CO2 emissions. Since each concept pursues only one of these two solutions, the totality of approaches is neither economically optimal nor, in many cases, economically feasible.

[0009] In addition to CO2 capture / reduction, there is also a fundamental industrial need for the cost-effective, energy-efficient and targeted capture of other gas components from gas mixture streams for gas purification or separation, e.g. nitrogen oxide capture from exhaust gases or oxygen extraction from air.

[0010] The invention is based on the objective of providing an integrated process that both balances the fluctuations in renewable energy generation, particularly electricity generation, over time and enables the effective reduction of CO2 emissions or other gas components in gas mixture flows in power plant and industrial processes. The aim is to overcome the disadvantages of existing storage and compensation solutions as well as the high costs and energy consumption of CCU / CCS processes or gas purification / gas separation processes in order to realize an economically viable overall solution.

[0011] The problem underlying the invention is solved by a method with the features of claim 1. The invention relates to a method for charging and / or discharging a thermal energy storage system using a gas mixture stream. The gas mixture stream comprises at least one gas component to be separated and at least one further gas component. The method further relates to separating the at least one gas component from the gas mixture stream. The method comprises the following steps, in particular in the order mentioned: compressing the gas mixture stream; charging and / or discharging at least one high-temperature thermal storage system using the gas mixture stream; expanding the gas mixture stream; charging and / or discharging at least one low-temperature cold storage system using the gas mixture stream.Before or after the charging and / or discharging of the at least one high-temperature thermal storage unit and / or before or after the charging and / or discharging of the at least one low-temperature cold storage unit, the at least one gas component is partially or completely separated from the gas mixture stream. After partial separation, a relevant portion of the gas component to be separated remains in the gas mixture stream. After complete separation, no relevant portion of the gas component to be separated remains in the gas mixture stream. It is also conceivable that before the charging and / or discharging of the at least one high-temperature thermal storage unit and / or after the charging and / or discharging of the at least one low-temperature cold storage unit, the at least one gas component to be separated is partially or completely separated from the gas mixture stream.

[0012] The process is based on the concept of integrating and combining renewable energy sources in electrical power supply systems with measures to reduce CO2 emissions during electricity generation and / or with measures for gas purification / separation of gas mixture streams. The high fluctuations of renewable energy in electricity generation can be compensated for by thermal energy storage, while simultaneously ensuring the minimization of greenhouse gases in power plants and energy-intensive industrial processes, or purifying / separating gas mixture streams. The combination of thermal energy storage and the compression and expansion of the gas mixture stream forms the basis of a power-to-heat-power storage system, or a Carnot battery, and is based on a (partially) closed or open Joule-Brayton cycle. The Carnot battery includes, among other things, power-to-heat conversion, heat storage, and the recovery of electricity from heat.

[0013] First, thermal energy from the gas mixture stream is stored in the thermal energy storage system (charging), during which the gas component is separated. The stored thermal energy can be used directly (power-to-heat-and-cold) to, for example, generate steam. For simplicity, the direct use of the thermal energy is also referred to as charging a thermal energy storage system. This involves mechanical charging with CO2 separation and a purely thermal discharge. Alternatively, the stored thermal energy can be converted back into electricity using the working machines (discharging), and the electricity can be fed into the grid (power-to-heat-and-cold-to-power). Thus, mechanical charging is followed by mechanical discharge.

[0014] If a gas component is separated during a process (loading or unloading), the process can be designed as an open process or a partially closed cycle. If no gas component is separated during a process (loading or unloading), the process can be designed as a closed cycle.

[0015] It is particularly advantageous that during the charging and / or discharging process of thermal energy storage systems, especially high-temperature (HT) thermal storage systems, medium-temperature (MT) thermal storage systems, and / or low-temperature (LT) cold storage systems (HT: high temperature, MT: medium temperature, LT: low temperature), at least one gas component can be selectively separated from the gas mixture stream in a process-integrated manner, close to the process. During charging, the process phase after the gas mixture stream has released heat at a high or medium temperature, e.g., to an HT thermal storage system and / or MT thermal storage system, and / or before the gas mixture stream absorbs heat at a low or medium temperature, e.g., from an LT cold storage system, an MT cold storage system, and / or the environment, is particularly advantageous. During discharging, the process phase before the gas mixture stream absorbs heat at a high or medium temperature, e.g.,particularly advantageous after the gas mixture flow has released heat at a low or medium temperature, e.g. to a low-temperature cold storage and / or to a medium-temperature cold storage and / or to the environment (or has absorbed cold from the low-temperature cold storage = discharge of the low-temperature cold storage).

[0016] The thermal storage systems are designated here according to the temperature ranges specified below, at which heat transfer between the thermal storage system and the gas (mixture) flow takes place. In a high-temperature (HT) thermal storage system, heat is preferably transferred at a high temperature between 350°C and 1200°C, particularly between 500°C and 1000°C. In a medium-temperature (MT) thermal storage system, heat is preferably transferred at a medium temperature between -50°C and 350°C, particularly between 0°C and 200°C. In a low-temperature (LT) cold storage system, heat is preferably transferred at a low temperature between -200°C and -50°C, particularly between -150°C and -100°C. The terms "high," "medium," and "low" are to be understood in relation to one another. Thus, for example, the temperature of heat transfer in an HT thermal storage system is higher than in an LT cold storage system.The temperature of the heat transfer in the MT heat storage system is preferably between the high temperature and the low temperature.

[0017] During the charging of the thermal energy storage system (charging process), after charging the at least one high-temperature (HT) heat storage unit and / or before charging the at least one low-temperature (NT) cold storage unit, at least one gas component can be partially or completely separated from the gas mixture stream. The charging process can then be followed by a simple thermal discharge without compression and / or expansion. Therefore, the stored thermal energy is not converted back into electricity. Alternatively, reconversion into electricity can also take place.

[0018] During the discharge of the thermal energy storage system (discharge process), after the discharge of the at least one low-temperature cold storage unit and / or before the discharge of the at least one high-temperature heat storage unit, the at least one gas component can be partially or completely separated from the gas mixture stream.

[0019] In a first embodiment, the method comprises the following steps, in particular in the order mentioned: compressing the gas mixture stream; charging the high-temperature (HT) heat storage unit using the gas mixture stream; expanding the gas mixture stream; charging the low-temperature (NT) cold storage unit using the gas mixture stream; wherein, after charging the HT heat storage unit and / or before charging the NT cold storage unit, the gas component is separated from the gas mixture stream (meaning heat extraction from the NT cold storage unit) in one or more steps.

[0020] In a second embodiment, the method comprises the following steps, in particular in the order mentioned: compressing the gas mixture stream; discharging the high-temperature (HT) heat storage unit using the gas mixture stream; expanding the gas mixture stream; discharging the low-temperature (LT) cold storage unit using the gas mixture stream; wherein, before discharging the HT heat storage unit and / or after discharging the LT cold storage unit, the gas component is separated from the gas mixture stream, and / or wherein, after discharging the LT cold storage unit and / or before discharging the HT heat storage unit, the gas component is separated from the gas mixture stream in one or more steps.

[0021] In a third embodiment, the method comprises the following steps, in particular in the order mentioned: compressing the gas mixture flow; charging the high-temperature (HT) heat storage unit using the gas mixture flow; expanding the gas mixture flow; charging the low-temperature (LT) cold storage unit using the gas mixture flow (meaning heat extraction from the LT cold storage unit); compressing the gas mixture flow; discharging the HT heat storage unit using the gas mixture flow; expanding the gas mixture flow; discharging the LT cold storage unit using the gas mixture flow;wherein, after charging the high-temperature (HT) heat storage unit and / or before charging the low-temperature (NT) cold storage unit, the gas component is separated from the gas mixture stream in one or more steps, and / or wherein, before discharging the HT heat storage unit and / or after discharging the NT cold storage unit, the gas component is separated from the gas mixture stream, and / or wherein, after discharging the NT cold storage unit and / or before discharging the HT heat storage unit, the gas component is separated from the gas mixture stream in one or more steps.;

[0022] It is conceivable that the HT heat storage or the NT cold storage will be replaced or supplemented by an MT heat storage or MT cold storage.

[0023] An advantageous aspect of the invention provides that the gas mixture stream is an exhaust gas, in particular flue gas, preferably from a production and / or power plant. The gas component to be partially or completely separated from the gas mixture stream can be CO2. Alternatively or additionally, other gas components, such as water vapor, nitrogen oxides, or oxygen, can also be separated. The dehumidified exhaust gas can, for example, consist of the following substances: 80 vol% N2, 15 vol% CO2, 5 vol% other trace gases.

[0024] An advantageous aspect of the invention provides that, particularly during the charging of the thermal energy storage system, during or after the charging of the high-temperature (HT) thermal storage unit, and / or during or before the charging of the low-temperature (LT) cold storage unit, the gas mixture flow is isobarically cooled in at least one first heat exchanger and / or expanded in a gas turbine and / or in an expander and / or in at least one throttle and / or in at least one nozzle, so that the gas component condenses and / or resublimates from the gas mixture flow. Accordingly, the gas component can be separated from the gas mixture flow or from the remaining parts of the gas mixture flow while maintaining essentially constant pressure.

[0025] An advantageous aspect of the invention provides that, particularly during the discharge of the thermal energy storage system, during or after the discharge of the low-temperature cold storage unit and / or before the discharge of the high-temperature heat storage unit, the gas mixture stream is isobarically cooled in at least a second heat exchanger and / or expanded in a gas turbine and / or in an expander and / or in at least one throttle and / or in at least one nozzle, such that the gas component condenses and / or resublimates from the gas mixture stream. The phase change of the gas component can occur between the charging of the high-temperature heat storage unit and the charging of the low-temperature cold storage unit. The charging process can be an open Joule-Brayton cycle. The phase change of the gas component can occur between the discharge of the low-temperature cold storage unit and the discharge of the high-temperature heat storage unit. The discharge process can be a closed Joule-Brayton cycle.

[0026] An advantageous aspect of the invention provides that, during the expansion of the gas mixture flow, the gas mixture flow expands in at least one gas turbine and / or in at least one expander and / or in at least one throttle and / or at least one nozzle, causing the gas component to condense and / or resublimate from the gas mixture flow. Thus, when generating technical work from a gas turbine, the gas component to be separated can be simultaneously separated from the gas mixture flow or from the remaining parts of the gas mixture flow. Consequently, a process step of the Carnot battery can be used to selectively separate a gas component, such as CO2.

[0027] An advantageous aspect of the invention provides that the charging of the HT heat storage unit is carried out by heat transfer from the compressed gas mixture stream to the HT heat storage unit, and / or that the discharging of the HT heat storage unit is carried out by heat transfer from the HT heat storage unit to the compressed gas mixture stream.

[0028] An advantageous aspect of the invention provides that the charging of the NT cold storage unit is carried out by heat transfer from the NT cold storage unit to the expanded gas mixture flow, and / or that the discharging of the NT cold storage unit is carried out by heat transfer from the expanded gas mixture flow to the NT cold storage unit.

[0029] An advantageous aspect of the invention provides that the charging and / or discharging of the high-temperature (HT) heat storage unit is carried out using a first heat transfer fluid or by direct contact between the compressed gas mixture stream and a first storage material of the HT heat storage unit. The HT heat storage unit can be designed as a fixed-bed heat storage unit. Alternatively, the HT heat storage unit can also be designed as a liquid tank heat storage unit.

[0030] An advantageous aspect of the invention provides that the charging and / or discharging of the low-temperature (LT) cold storage unit is carried out using a second heat transfer fluid or by direct contact between the expanded gas (mixture) flow or remaining gas (mixture) flow and a second storage material of the LT cold storage unit. The LT cold storage unit can be designed as a fixed-bed cold storage unit. Alternatively, the LT cold storage unit can also be designed as a liquid tank cold storage unit.

[0031] An advantageous aspect of the invention provides that the charging and / or discharging of the MT thermal storage unit is carried out using a third heat transfer fluid or by direct contact between the compressed or expanded gas (mixture) flow or remaining gas (mixture) flow and a third storage material of the MT thermal storage unit and / or MT cold storage unit. The MT thermal storage unit can be configured as a fixed-bed thermal storage unit and / or the MT cold storage unit can be configured as a fixed-bed cold storage unit. Alternatively, the MT thermal storage unit can be configured as a liquid tank thermal storage unit and / or the MT cold storage unit can be configured as a liquid tank cold storage unit.

[0032] The first, second, and / or third heat transfer fluid can be liquid or gaseous. The first and / or second heat transfer fluids can be identical or different. The first and / or second heat transfer fluid can be chosen from, for example, one of the following substances: water, oil, molten salt, liquid metal, air, helium, nitrogen, CO2.

[0033] The first and / or second storage material can be solid or liquid. The first and / or second storage material can be identical or different. The first and / or second storage material can be selected from, for example, one of the following materials: ceramics, such as aluminum oxide or silicon carbide; bulk materials, such as quartz sand or basalt; concrete or ceramic- or cement-based precast concrete blocks; graphite; or carbon materials. The following liquid materials can be used for the construction of heat and / or cold storage systems as liquid tank storage: molten salts (e.g., nitrate mixtures) and thermal oils. For low-temperature cold storage, pressurized liquefied gases, such as liquid CO2, can also be used.

[0034] An advantageous aspect of the invention provides that the separated gas component, in particular the separated CO2, is stored in a storage tank, especially a CO2 storage tank, in gaseous, liquid, and / or solid form. For the sake of simplicity, it will continue to be described as a gas component, even if it exists in a different state of matter due to condensation or resublimation. The storage tank ensures that the separated gas component does not remix with the gas mixture stream or escape uncontrollably into the environment. Furthermore, the gas component can be further processed, for example, by producing dry ice from it, or transported further, for example, by conveying the gas component in liquid form through pipelines or trucks.

[0035] An advantageous aspect of the invention provides that the separated gas component is stored in solid form in the storage tank and subsequently used to cool the gas mixture flow during the charging or discharging process of the thermal energy storage system. This is achieved by utilizing the phase transition of the separated gas component from solid to liquid and the associated enthalpy of fusion. This results in heat being extracted from the gas mixture flow during the charging or discharging process of the thermal energy storage system and supplied to the solid separated gas component for melting or liquefaction. A recuperator or a heat exchanger can be provided for heat transfer, with the piping system guiding the gas mixture flow to or through the storage tank. In a further embodiment, an additional heat transfer fluid could be used in a separate heating circuit to transfer heat from the process to the storage tank.This allows for further process control and increased efficiency. In particular, the separation rate of the gas component can be increased.

[0036] An advantageous aspect of the invention provides that the gas (mixture) stream remaining after the separation of the gas component is at least partially recycled back into the process. Accordingly, it is conceivable that the gas mixture stream consists partly of exhaust gas from a power plant or production facility and partly of a gas (mixture) stream with reduced or no separating gas component content. The loading process is therefore at least partially closed. By separating the gas component only partially, rather than completely, in one process cycle and then separating it again in a subsequent cycle, the process can be operated with particular efficiency. The mass ratio of the exhaust gas and the gas mixture stream with reduced separating gas component content is preferably in the range of 70:30 to 95:5, and particularly between 80:20 and 90:10.

[0037] An advantageous aspect of the invention provides that the gas mixture stream is pre-treated, intermediately treated, and / or post-treated before, during, or after the respective steps of the process. Furthermore, it is conceivable that multiple compression stages, multiple expansion stages, and / or multiple heat exchanger stages are provided. This allows the efficiency of the process to be further increased.

[0038] An advantageous aspect of the invention provides that, during the loading process, the gas mixture stream is pre-compressed in at least one compression unit with a compressor and intermediately cooled by a heat exchanger before being compressed to the maximum process pressure. Subsequently, the gas mixture stream can be compressed to the maximum process pressure in a compressor.

[0039] Cooling and / or heating can be achieved either via a heat exchanger or a recuperator. In a heat exchanger, heat is added to or removed from the system from the outside. In a recuperator, a gas mixture stream from one process step is cooled or heated by a gas mixture stream from another process step, so that the heat remains within the system.

[0040] An advantageous aspect of the invention provides that, during the charging process, the gas mixture flow is cooled after the HT heat storage unit has been charged.

[0041] An advantageous aspect of the invention provides that during the loading process, the gas mixture stream expands in at least one gas turbine. It is advantageous if the gas component is separated both upstream and downstream of the at least one gas turbine. For this purpose, a separator can be provided upstream and downstream of each gas turbine. It is conceivable that in a separator located upstream of an expander and / or gas turbine, the gas component is separated in liquid form, and in a separator located downstream of the expander and / or gas turbine, the gas component is separated in liquid and / or solid form. Multiple expansion stages can also be provided, such that several expanders are used, e.g., several gas turbines, or at least one gas turbine and at least one throttle, or at least one gas turbine and at least one nozzle. Furthermore, the gas component can be separated in liquid and / or solid form between two adjacent expanders.

[0042] An advantageous aspect of the invention provides that, during discharge, the gas mixture flow is preheated before being heated by the high-temperature heat storage system, particularly in a heat exchanger or recuperator. A further advantageous aspect of the invention provides that this preheating takes place before compression or the first compression stage.

[0043] An advantageous aspect of the invention provides that the gas mixture flow is pre-cooled after driving the working machine and / or gas turbine and / or before cooling by the NT cold storage, in particular in or at a medium temperature storage and / or at the environment and / or at a heat consumer and / or at a recuperator.

[0044] The problem underlying the invention is also solved by a device with the features of claim 9. The invention relates to a device for charging and / or discharging a thermal energy storage system by means of a gas mixture stream comprising a gas component, in particular CO2, and for separating this gas component from the gas mixture stream, comprising: a piping system for guiding the gas mixture stream; at least one compressor for compressing the gas mixture stream; a high-temperature thermal storage unit for storing and / or releasing thermal energy at a high temperature; in particular, expansion of the gas mixture stream by means of at least one expansion unit and / or gas turbine and / or throttle and / or nozzle and / or expander;at least one heat exchanger for transferring thermal energy at a low temperature and / or one low-temperature cold storage unit for storing and / or releasing thermal energy at a low temperature;At least one separator, in particular a CO2 separator, for separating the gas component from the gas mixture stream, wherein the at least one separator is arranged between the high-temperature (HT) thermal storage tank and the low-temperature (LT) cold storage tank or between the HT thermal storage tank and the at least one heat exchanger. It is also conceivable that the at least one separator is arranged between the LT cold storage tank and the HT thermal storage tank or between the at least one heat exchanger and the HT thermal storage tank. The piping system preferably connects the further components of the device in the following order: at least one compressor, at least one HT thermal storage tank, at least one separator and at least one heat exchanger and / or at least one LT cold storage tank and / or at least one expander and / or at least one expansion unit.

[0045] The device is also based on the concept of integrating gas separation into the charging and / or discharging process. It is particularly advantageous that, during the charging and / or discharging process of the thermal energy storage system, at least one gas component can be selectively separated from the gas mixture stream in a process-integrated manner. The process range is particularly advantageous after the gas mixture stream has released heat at a high or medium temperature, e.g., to an HT storage system and / or MT storage system and / or the environment, and / or before the gas mixture stream absorbs heat at a low temperature, e.g., from an LT storage system.The fact that it has been transferred to an NT memory, an MT memory and / or the environment is also particularly advantageous.

[0046] An advantageous aspect of the invention provides that the at least one compressor, the high-temperature heat storage unit, the at least one heat exchanger and / or the low-temperature cold storage unit and the separator and in particular the expansion unit, preferably the gas turbine, are connected to each other by the piping system in such a way that a gas component from a gas mixture flow conveyed through the piping system can be separated or is separated in the at least one separator.

[0047] An advantageous aspect of the invention provides that the device includes a phase change unit for changing the phase of the gas component. The phase change unit preferably comprises at least one of the following components: at least one further heat exchanger for cooling the gas mixture flow, in particular isobarically; at least one gas turbine for expanding the gas mixture flow; and / or at least one throttle for expanding the gas mixture flow; and / or at least one nozzle for expanding the gas mixture flow. The phase change unit is preferably configured such that the at least one gas component to be separated condenses and / or resublimes within the phase change unit.

[0048] An advantageous aspect of the invention provides that the device includes a driven machine, in particular a gas turbine. The driven machine can be driven by the gas mixture flow. The enthalpy flow of the gas mixture flow can be converted into electrical current by means of the driven machine. It is conceivable that the at least one compressor is driven by the at least one driven machine. The at least one compressor and the at least one driven machine can be arranged on a common drive shaft. The electrical current can be fed into the grid (with the exception of the power consumption of the at least one compressor).

[0049] An advantageous aspect of the invention provides that the at least one separator is arranged upstream and / or downstream of the machine. The terms "upstream" and "downstream" are to be understood within the context of the disclosure as "upstream of the process" and "downstream of the process," respectively. For example, if a separator is arranged upstream of a machine, this means that the gas mixture flow first passes through the separator and then through the machine (the separator is upstream of the machine). It is conceivable that a CO2 separator, particularly directly, is arranged upstream and a CO2 separator, particularly directly, is arranged downstream of the gas turbine. Within the context of the disclosure, the term "directly" means that only the piping system and no other component, such as a heat exchanger, is arranged between the components in question.

[0050] An advantageous aspect of the invention provides that the HT heat storage unit is a fixed-bed heat storage unit and / or the NT cold storage unit is a fixed-bed cold storage unit.

[0051] An advantageous aspect of the invention provides that the HT heat storage unit can also be a liquid tank heat storage unit, and / or the NT cold storage unit can be a liquid tank cold storage unit.

[0052] An advantageous aspect of the invention provides that at least one compressor unit for pretreating the gas stream is connected upstream of the compressor, wherein the at least one compressor unit comprises at least one further compressor and a compressor heat exchanger and / or a compressor recuperator. This allows the efficiency of the process to be further increased.

[0053] An advantageous aspect of the invention provides that at least one working machine unit is connected upstream of the at least one working machine, wherein the at least one working machine unit comprises a further working machine, in particular a gas turbine, and a heat transfer system with the high-temperature heat storage unit. This allows the efficiency of the process to be further increased.

[0054] An advantageous aspect of the invention provides that the device further comprises: a medium-temperature storage unit for storing thermal energy at a medium temperature.

[0055] An advantageous aspect of the invention provides that the device includes a previously described separation storage unit. It is conceivable that the device further includes a dry ice production plant for producing dry ice from the separated gas component, in particular for CO2 dry ice.

[0056] The problem underlying the invention is also solved by a system with the features of claim 14. The system comprises a previously described device and a power plant or production plant, wherein exhaust gas from the power plant or production plant can be supplied to the device as a gas mixture stream. For this purpose, the system preferably has an exhaust gas line that fluidically connects the device and the power plant or production plant. Preferably, the device is designed and configured to carry out the previously described method such that thermal energy storage devices can be charged and / or discharged and a gas component can be separated from the gas mixture stream or is separated. The system preferably has at least one separation storage device.

[0057] The problem underlying the invention is also solved by a method with the features of claim 15. The invention relates to a method for charging and discharging a thermal energy storage system. The method comprises the following steps, preferably in the order mentioned: charging the thermal energy storage system using a gas mixture stream comprising a gas component, in particular CO2, wherein, during charging the thermal energy storage system, at least a portion of the gas component is separated from the gas mixture stream, so that a gas component-reduced or gas component-free, in particular CO2-reduced or CO2-free, gas (mixture) stream is provided; and discharging the thermal energy storage system using the gas component-reduced or gas component-free gas (mixture) stream provided during charging the thermal energy storage system.The thermal energy storage system preferably comprises a high-temperature (HT) heat storage unit and a low-temperature (NT) cold storage unit. The gas component is preferably separated between the charging of the HT heat storage unit and the charging of the NT cold storage unit. Furthermore, during the discharging of the thermal storage system, the gas component can be further separated from the gas-component-reduced gas mixture stream. The charging and discharging process can be repeated multiple times.

[0058] An advantageous aspect of the invention provides that the discharge of the thermal energy storage system takes place with or without the separation of a gas component from the gas component-reduced, in particular CO2-reduced, gas mixture stream.

[0059] Further advantages, features, and details will become apparent from the following description, in which various embodiments of the invention are illustrated with reference to the drawing. The features mentioned in the claims and the description can each be essential to the invention individually or in any combination.

[0060] They show: Fig. 1 a first embodiment for charging and / or discharging a thermal energy storage system and for separating a gas component; Fig. 2 a second embodiment for charging and / or discharging a thermal energy storage device and for separating a gas component; Fig. 3 a third embodiment for charging a thermal energy storage device and for separating a gas component; Fig. 4 a fourth embodiment for charging a thermal energy storage device and for separating a gas component; Fig. 5 a fifth embodiment for discharging a thermal energy storage device; Fig. 6 a sixth embodiment for discharging a thermal energy storage device; and Fig. 7 a seventh embodiment for discharging a thermal energy storage device.

[0061] According to Fig. 1. The device 10 for charging and / or discharging a thermal energy storage system 12 by means of a gas mixture stream 14 comprises a gas component 16. The device is preferably integrated into a process between a power plant or production plant 18 and a separation storage unit 20 for separating the gas component 16 from the gas mixture stream 14. Furthermore, a connection to an energy source or a power grid 19 may be provided.

[0062] Accordingly, exhaust gas, in particular flue gas, from power plant 18 can be supplied to the device 10 as a gas mixture stream 14. It is therefore advantageous if the device 10 is located close to the power plant. The device 10 stores the energy of the compressed enthalpy stream of the exhaust gas in the thermal energy storage system 12 (difference between compression and expansion power) and also separates a gas component 16 from the exhaust gas. This is particularly well suited for separating CO2 from CO2-containing exhaust gas. Other gas mixtures can also be used as the gas mixture stream 14. Depending on their composition, other gas components can also be separated from the gas mixture stream 14. The separated gas component 16 can then be stored in the separation storage tank 20 in solid and / or liquid form. The separated gas component 16, stored in the separation storage tank 20, can be transported further in liquid form.It is also conceivable that the separated gas component 16 could be used to produce dry ice. It is conceivable that the device 10 separates a gas component 16 from a gas mixture stream 14 during the discharge of the thermal energy storage system 12.

[0063] The device 10 has according to Fig. 2. A compressor 22 is used to compress the gas mixture stream 14. The gas mixture stream 14 can be, as previously described, exhaust gas from a power plant or production facility 18, which is fed to the compressor 22. In the compressor 22, the gas mixture stream 14 can be compressed to a final pressure of 10 bar to 150 bar. For a gas composition of approximately 85 vol.% N2 and approximately 15 vol.% CO2, approximately 20 bar to 25 bar, in particular 22 bar, are required for a CO2 separation efficiency of 30%, and approximately 65 bar to 75 bar, in particular 70 bar, are required for a CO2 separation efficiency of 90%. The device 10 also has a piping system 24 with several lines. The piping system 24 connects the compressor 22 to a first heat exchanger 26 or to a high-temperature heat storage tank 28 (HT heat storage tank). Depending on the process (charging or discharging), the HT heat storage unit 28 is charged or discharged by the gas mixture flow 14.During charging, heat is transferred from the gas mixture stream 14 to the high-temperature (HT) thermal storage unit 28. During discharging, heat is transferred from the HT thermal storage unit 28 to the gas mixture stream 14. The first heat exchanger 26 can be arranged between the gas mixture stream 14 and the HT thermal storage unit 28, with heat transfer taking place via a first heat transfer fluid. Alternatively, the gas mixture stream 14 can flow directly through the HT thermal storage unit 28. The HT thermal storage unit 28 can be designed as a fixed-bed storage unit.

[0064] The device 10 further features according to Fig. 2. A working machine 30, in particular a gas turbine, is used. The first heat exchanger 26 or the high-temperature heat storage unit 28 and the working machine 30 are connected to each other by means of the piping system 24. The working machine 30 is driven by the gas mixture flow 14. It is conceivable that the working machine 30 drives the compressor 22. Alternatively or additionally, the compressor 22 can be supplied with energy from an external source. Alternatively or additionally to the working machine 30, a throttle and / or a nozzle can be provided. In the working machine 30 and / or throttle and / or nozzle, the gas mixture flow 14 can be expanded, in particular to a final pressure of typically atmospheric pressure of approximately 1 bar.

[0065] The device 10 has according to Fig. 2. A low-temperature cold storage unit 32 (LT cold storage unit) is provided. Depending on the process (charging or discharging), the LT cold storage unit 32 is charged or discharged by the gas mixture flow 14. During charging, heat is transferred from the LT cold storage unit 32 to the gas mixture flow 14. During discharging, heat is transferred from the gas mixture flow 14 to the LT cold storage unit 32. A second heat exchanger 34 can be arranged between the gas mixture flow 14 and the high-temperature heat storage unit 28, with heat transfer taking place via a second heat transfer fluid. Alternatively, the gas mixture flow 14 can flow directly through the LT cold storage unit 32. The high-temperature heat storage unit 28 can be designed as a fixed-bed storage unit. The piping system 24 connects the working machine 30 to the LT cold storage unit 32.

[0066] Between the high-temperature (HT) heat storage tank 28 and the low-temperature (NT) cold storage tank 32, at least one separator 36 is provided for separating at least one gas component 16 from the gas mixture stream 14. The at least one separator 36 can be configured as at least one CO2 separator 36, wherein the gas mixture stream 14 comprises CO2. According to Fig. 2. A first separator 36 is located upstream of the working machine 30, and a second separator 36 is located downstream of the working machine 30. It is also conceivable that only one separator 36 is provided. The device 10 is preferably designed such that the gas component 16 separates from the gas mixture stream 14, in particular by the gas component 16 condensing (gaseous -> liquid) and / or resublimating (gaseous -> solid). This can be achieved by means of and / or in a phase change unit. The phase change unit can be designed as a heat exchanger, recuperator, gas turbine, throttle, and / or nozzle, which is designed such that the at least one gas component condenses and / or resublimates.

[0067] The separated gas component 16 can then be separated in the separator 36 and fed to the separator storage tank 20. The gas component-reduced or gas component-free gas (mixture) stream 14 can be processed according to Fig. 3. The gas mixture is then fed to a gas storage tank 38. It is conceivable that a portion of the gas-component-reduced gas mixture flow 14 is additionally fed to the compressor 22, e.g., alongside the exhaust gas. Another portion of the gas-component-reduced gas mixture flow 14 can be fed to the gas storage tank 38. Another portion of the gas-component-reduced gas mixture flow 14 can be emitted into the environment.

[0068] The loading process can preferably be designed as an open modified Joule-Brayton process. The unloading process can preferably be designed as a closed modified Joule-Brayton process, wherein preferably the gas-component-reduced gas mixture stream 14 or the gas-component-free gas (mixture) stream 14 from the previous loading process is used.

[0069] During the charging and / or discharging process, the piping system 24 connects the components of the device 10 such that the gas mixture flow 14 first passes through the compressor 22, the high-temperature (HT) thermal storage unit 28, the driven machine 30, and then the low-temperature (LT) cold storage unit 32. During the charging process, the gas mixture flow 14 preferably passes through the at least one separator 36 after the HT thermal storage unit 28 and before the LT cold storage unit 32. During the discharging process, the gas mixture flow 14 preferably passes through the at least one separator 36 after the LT cold storage unit 32 and before the HT thermal storage unit 28, in which case at least one separator 36 is arranged alternatively or additionally after the LT cold storage unit 32 and before the HT thermal storage unit 28. Alternatively, it is conceivable that the at least one gas component 16 is separated only during the charging of the thermal energy storage unit 12. Separation can be omitted during unloading.In this case, the arrangement of at least one separator 36 after the high-temperature (HT) heat storage tank 28 and / or before the low-temperature (NT) cold storage tank 32 is sufficient. It is also conceivable that only the HT heat storage tank 28 is provided, whereby the heat transfer to the NT cold storage tank 32 can be replaced by heat transfer to the environment.

[0070] The efficiency of loading, unloading, and separation can be improved by further measures. Further embodiments of the device 10 according to Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. Figure 7 shows these measures in different forms. The embodiments can include, among other things, the components of the embodiments described above. Fig. 1 or Fig. 2 exhibit. The measures described below can also be applied to device 10 according to Fig. 1 or Fig. 2 can be applied.

[0071] According to Fig. The device 10 includes a compressor unit 40. Depending on the composition (proportion of the gas component 16 to be separated) and condition (temperature, pressure) of the gas mixture stream 14, the compressor unit 40 pre-treats the gas mixture stream. The compressor unit 40 comprises a pre-compressor 42 and a compressor heat exchanger 44, or a heat exchanger downstream of the compressor. One or more compressor units 40 can be provided as one or more compression stages. Accordingly, the gas mixture stream 14 can be pre-compressed and / or preheated and / or pre-cooled one or more times.

[0072] Furthermore, heat transfer for cooling the gas mixture flow 14 can take place downstream of the high-temperature (HT) heat storage unit 28. For this purpose, a third heat exchanger 46 and / or a first recuperator 48 can be provided. The piping system 24 connects the HT heat storage unit 28 and the working machine 30 to the third heat exchanger 46 and / or the first recuperator 48. The gas mixture flow 14, expanded in the working machine 30, can be used for cooling in the first recuperator 48. Several expansion stages can also be provided. For this purpose, several working machines 30 can be arranged in the piping system 24 between the HT heat storage unit 28 and the low-temperature (LT) cold storage unit 32. A separator 36 can be installed upstream of each working machine 30. Furthermore, a separator 36 can be provided downstream of at least one working machine 30 and upstream of the LT cold storage unit 32.Additionally, a throttle 50, in particular a nozzle, can be provided between the at least one working machine 30 and the downstream separator 36 to further expand the gas mixture flow 14. As previously described, the expanded gas mixture flow 14 can pass through the first recuperator 48 either before or after the low-temperature cold storage tank 32. Thus, the expanded gas mixture flow 14 is preheated before the low-temperature cold storage tank 32 or reheated after the low-temperature cold storage tank 32. Finally, the gas mixture flow 14 can be discharged from the system. It is conceivable that a portion of the gas mixture flow 14 is returned to the process.

[0073] According to Fig. 3. It is conceivable that the supplied gas mixture stream 14 is further pretreated for charging. For this purpose, a first medium-temperature storage tank 52 can be provided upstream of the compressor 22. The first medium-temperature storage tank 52 can be charged and / or discharged at a medium temperature using the gas mixture stream 14. This preferably preheats the gas mixture stream 14 before compression during the charging process using the first medium-temperature storage tank 52.

[0074] According to Fig. 5. The discharge process can be designed as a cyclic process. The device 10 indicates this as shown in [reference]. Fig. 3. One or more compressor units 40 are located upstream of the compressor 22. The device 10 preferably has a fourth heat exchanger 54, which is located downstream of the compressor 22 and upstream of the high-temperature heat storage tank 28. By means of the fourth heat exchanger 54, the gas mixture flow 14 can be pre-cooled or pre-heated upstream of the high-temperature heat storage tank 28.

[0075] The device 10 can also be operated as a power-to-heat-and-cold system without reconversion to electricity. In this case, at least one high-temperature (HT) heat storage tank 28 would be provided for releasing the heat and at least one low-temperature (NT) cold storage tank 32 for releasing the cold, e.g., to a connected industrial process. In this case, the circulation of a gas mixture flow 14 can be omitted. In this embodiment, separation of a gas component between the HT heat storage tank 28 and the NT cold storage tank 32 can also occur. The phase change for the separation can be effected by heat release at the HT heat storage tank 28 and / or by expansion in an expansion unit.

[0076] Furthermore, according to Fig. 5. It is conceivable that several working machines 30 are provided. The compressors 22 can be driven by the working machines 30. Between two adjacent working machines 30, the piping system 24 can be designed such that the expanded gas mixture flow 14 is routed past the high-temperature heat storage unit 28, so that the high-temperature heat storage unit 28 can be discharged by the gas mixture flow 14 in several discharge stages. In Fig. In example 5, no gas component 16 is separated, so that the piping system 24 or the gas mixture flow 14 is fluidically separated from the separator storage tank 20. A fifth heat exchanger 56 can be provided between the working machine 30 and the low-temperature cold storage tank 32 for pre-cooling the expanded gas mixture flow 14.

[0077] According to Fig. 5 and Fig. 6. The heat absorption of the expanded gas mixture flow 14 can occur in several discharge stages. According to Fig. A second recuperator 58 is provided in section 5. In the second recuperator 58, the gas mixture flow 14 cooled in or at the low-temperature cold storage tank 32 is used to pre-cool the expanded gas mixture flow 14. Accordingly, the piping system 24 is designed such that the gas mixture flow 14 after the low-temperature cold storage tank 32 is routed past the gas mixture flow 14 before the low-temperature cold storage tank 32.

[0078] Alternatively or additionally, it is conceivable that according to Fig. 6. A second medium-temperature storage tank 60 is connected upstream of the low-temperature cold storage tank 32. The second medium-temperature storage tank 60 is preferably arranged between the driven machine 30 and the low-temperature cold storage tank 32. Accordingly, during discharge, the gas mixture flow 14 is first cooled to a medium temperature at or within the second medium-temperature storage tank 60 and then cooled to a low temperature at or within the low-temperature cold storage tank 32. Finally, the gas mixture flow 14 is returned to the compressor 22 or the compressor unit 40. It is conceivable that the first medium-temperature storage tank 52 and the second medium-temperature storage tank 60 are designed as a single medium-temperature storage tank, with the gas mixture flow 14 interacting with the medium-temperature storage tank in different process steps depending on the process type.

[0079] The above information regarding the arrangement of components refers to the flow direction of the gas mixture stream 14, which runs clockwise in the figures unless explicitly stated otherwise. Thus, for example, the arrangement of a second medium-temperature storage tank 60 between a working machine 30 and a low-temperature cold storage tank 32 means that the gas mixture stream 14 first passes through the working machine 30, then the second medium-temperature storage tank 60, and then the low-temperature cold storage tank 32.

[0080] In Fig. Figure 4 shows a further embodiment of a device 10 during loading. In this embodiment, a first medium-temperature storage tank 52 for preheating the gas mixture flow 14, a compressor unit 40 and a compressor 22 for staged compression of the gas mixture flow 14, a high-temperature heat storage tank 28, a first recuperator 48, a working machine 30 coupled to the compressor 22 and the compressor unit 40, a separator 36 downstream of the working machine 30, and a low-temperature cold storage tank 32 are provided in the specified order. The gas component 16 separated in the separator 36 can be stored in liquid or solid form in the separator storage tank 20 and further processed there, for example, for dry ice production or liquefied for onward transport. The gas component-reduced gas (mixture) flow is finally withdrawn from the process and, for example, released into the environment.

[0081] In Fig. Figure 7 shows another embodiment of a device 10 during unloading. In comparison to Fig. 2. No separator 36 is provided. In addition, a heat exchanger 54 is provided between the compressor 22 and the high-temperature (HT) thermal storage tank 28 for pre-cooling or pre-heating the compressed gas mixture flow 14. Furthermore, a second medium-temperature storage tank 60 and a low-temperature (LT) cold storage tank 32 are provided. For further pre-treatment before discharging the second medium-temperature storage tank 60 and the LT cold storage tank 32, another heat exchanger 56 can be provided for pre-cooling or pre-heating the expanded gas mixture flow 14. The discharge process can also be designed as a cycle. The gas mixture flow 14 can be the gas mixture flow 14 previously reduced in gas components during the charging process or a gas component-free gas flow.

[0082] The piping system 24 can be designed such that switching between the loading and unloading processes is possible, for example, by opening and closing valves. Accordingly, for example, a Fig. The separator 36 shown in Figure 3 is active during loading and inactive during unloading. It is conceivable that the gas mixture flow 14 is directed through the separator 36 during loading and through a bypass (not shown) during unloading. Reference symbol list 10 Device 12 thermal energy storage system 14 Gas mixture flow or gas flow 16 gas component to be separated 18 Power or production plant 20 separator tanks 22 Compressor 24-pipe system 26 first heat exchanger 28 High-temperature heat storage (HT heat storage) 30 working machine 32 Low-temperature cold storage units (LT cold storage units) 34 second heat exchanger 36 separators 38 gas storage tanks 40 compressor unit 42 Pre-compressor 44 Compressor heat exchangers 46 third heat exchanger 48 first recuperator 50 throttle / nozzle 52 first medium-temperature heat storage (first MT heat storage) 54 fourth heat exchanger 56 fifth heat exchanger 58 second recuperator 60 second medium-temperature heat storage (second MT heat storage)

Claims

Method for charging and / or discharging a thermal energy storage system (12) using a gas mixture stream (14) comprising a gas component (16) and for separating the gas component (16) from the gas mixture stream (14), comprising: a) compressing the gas mixture stream (14); b) charging and / or discharging a high-temperature thermal storage device (28) using the gas mixture stream (14); c) expanding the gas mixture stream (14); d) charging and / or discharging a low-temperature cold storage device (32) using the gas mixture stream (14); wherein the gas component (16) is separated from the gas mixture stream (14) before or after charging and / or discharging the high-temperature thermal storage device (28) and / or before or after charging and / or discharging the low-temperature cold storage device (32). Method according to claim 1, wherein the gas mixture stream (14) is an exhaust gas, in particular flue gas, of a production and / or power plant (18), and wherein the gas component (16) is CO2. A method according to claim 1 or 2, wherein, during the charging of the thermal energy storage system (12) according to step b) and before step c), the gas mixture flow (14) is cooled isobarically in at least one first heat exchanger (26) and / or, according to step c), expands in at least one gas turbine and / or in at least one throttle (50) and / or in at least one nozzle, such that the gas component (16) from the gas mixture flow (14) condenses and / or resublimates, and / or wherein, during the discharging of the thermal energy storage system (12) according to step d) and before step b), the gas mixture flow (14) is cooled isobarically in at least one second heat exchanger (34) and / or expands in at least one throttle (50) and / or in at least one nozzle, such that the gas component (16) from the gas mixture flow (14) condenses and / or resublimates. Method according to one of the preceding claims, wherein according to step b) the charging of the high-temperature heat storage (28) is carried out by heat transfer from the compressed gas mixture flow (14) to the high-temperature heat storage (28), and / or wherein according to step b) the discharging of the high-temperature heat storage (28) is carried out by heat transfer from the high-temperature heat storage (28) to the compressed gas mixture flow (14), and / or wherein according to step d) the charging of the low-temperature cold storage (32) is carried out by heat transfer from the low-temperature cold storage (32) to the expanded gas mixture flow (14), and / or wherein according to step d) the discharging of the low-temperature cold storage (32) is carried out by heat transfer from the expanded gas mixture flow (14) to the low-temperature cold storage (32). Method according to claim 4, wherein according to step b) the charging and / or discharging of the high-temperature heat storage (28) is carried out using a first heat transfer fluid or by direct contact between the compressed gas mixture flow (14) and a first storage material of the high-temperature heat storage (28), and / or wherein according to step d) the charging and / or discharging of the low-temperature cold storage (32) is carried out using a second heat transfer fluid or by direct contact between the expanded gas mixture flow (14) and a second storage material of the low-temperature cold storage (32). Method according to one of the preceding claims, wherein the separated gas component (16), in particular CO2, is stored in liquid and / or solid form in a separation storage tank (20), in particular a CO2 storage tank. Method according to one of the preceding claims, wherein the gas component-reduced gas mixture flow (14) or gas component-free gas mixture flow (14) or gas component-free gas flow obtained after separation of the gas component (16) is at least partially recycled to the method. Method according to one of the preceding claims, wherein the gas mixture stream (14) according to step c) expands in at least one working machine (30), wherein the gas component (16), in particular CO2, is separated from the gas mixture stream (14) before and / or after the at least one working machine (30). Device (10) for charging and / or discharging a thermal energy storage system (12) by means of a gas mixture stream (14) comprising a gas component (16) and for separating the gas component (16) from the gas mixture stream (14), comprising: - a piping system (24) for conducting the gas mixture stream (14); - at least one compressor (22) for compressing the gas mixture stream (14); - a high-temperature thermal storage unit (28) for storing and / or releasing thermal energy at a high temperature; - at least one heat exchanger (26, 34, 46, 54, 56) for transferring thermal energy at a low temperature and / or a low-temperature cold storage unit (32) for storing and / or releasing thermal energy at a low temperature;- at least one separator (36) for separating the gas component (16) from the gas mixture stream (14), wherein the at least one separator (36) is arranged between the high-temperature heat storage (28) and the low-temperature cold storage (32) or between the low-temperature cold storage (32) and the high-temperature heat storage (28) or between the high-temperature heat storage (28) and the at least one heat exchanger (26, 34, 46, 54, 56). Device (10) according to claim 9, wherein the at least one compressor (22), the high-temperature heat storage unit (28), the at least one heat exchanger (26, 34, 46, 54, 56) and / or the low-temperature cold storage unit (32) and the separator (36) are connected to each other by the piping system (24) in such a way that a gas component (16) from a gas mixture flow (14) conveyed through the piping system (24) can be separated or is separated in the at least one separator (36). Device (10) according to claim 9 or 10, wherein the device (10) comprises a phase change unit (14, 30, 50) for changing the phase of the gas component (16), wherein the phase change unit (14, 30, 50) comprises at least one of the following components: - at least one or more heat exchangers for isobarically cooling the gas mixture flow (14), and / or - at least one working machine (30), in particular a gas turbine, for expanding the gas mixture flow (14), and / or - at least one throttle (50) for expanding the gas mixture flow (14), and / or - at least one nozzle for expanding the gas mixture flow (14), wherein the phase change unit (14, 30, 50) is configured such that the gas component (16) condenses and / or resublimates in the phase change unit (14, 30, 50). Device (10) according to one of claims 9 to 11, wherein the at least one separator (36) is provided for separating CO2 from the gas mixture stream (14), wherein the at least one CO2 separator (36) is located upstream or downstream of the at least one working machine (30). Device (10) according to one of claims 9 to 12, wherein the device (10) further comprises: - medium temperature storage (52, 60) for storing and / or releasing thermal energy at a medium temperature. System comprising a device (10) according to any one of the preceding claims 9 to 13 and a power plant (18) or a production plant, wherein an exhaust gas from the power plant (18) or production plant can be supplied to the device (10) as a gas mixture stream (14) or is supplied to it. A method for charging and discharging a thermal energy storage system (12), comprising: - charging the thermal energy storage system (12) using a gas mixture stream (14) comprising a gas component (16), in particular CO2, wherein, during charging the thermal energy storage system (12), at least a part of the gas component (16) is separated from the gas mixture stream (14), so that a gas component-reduced, in particular CO2-reduced, gas mixture stream (14) or a gas component-free, in particular CO2-free, gas mixture stream (14) is provided, and - discharging the thermal energy storage system (12) using the gas component-reduced, in particular CO2-reduced, gas mixture stream (14) or the gas component-free, in particular CO2-free, gas mixture stream (14) provided during charging the thermal energy storage system (12).especially CO2-free, gas-generated electricity (14). Method according to claim 15, wherein the discharge of the thermal energy storage system (12) is carried out with or without the separation of a gas component (16) from the gas component-reduced, in particular CO2-reduced, gas mixture stream (14).

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