EP4317761A1 - Storage device for storing gas - Google Patents

Abstract

The present invention relates, among other things, to a storage device (40) for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, comprising an expandable storage chamber (41), which is designed as a piston accumulator, with a first piston storage element designed as a liquid chamber ( 42), into which liquid (46) can be filled up to a defined liquid level (47) or into which liquid (46) is filled up to a defined liquid level (47), with a second piston accumulator element (48) designed as a reciprocating piston element, the Piston storage elements (42, 48), in particular concentric, are placed inside one another in opposite directions, the piston storage elements (42, 48) being axially movable relative to one another, and with a gas inlet line (54) and with a gas outlet line (56). In order to be able to release the stored gas to the outside in a particularly controlled manner, the first piston storage element (42) is located on the outside in relation to the second piston storage element (48) and between an outer surface (81) of the second piston storage element (48) and an inner surface (82) of the first Piston storage element (42) is formed with a, in particular circumferential, gap (53). Furthermore, it is provided that the gas inlet line (54) and the gas outlet line (56) end (55, 57) above the defined liquid level (47) for the liquid (46) in the second piston storage element (48).

Description

The present invention firstly relates to a storage device for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, according to the preamble of patent claim 1. Furthermore, the invention relates to an energy system, in particular a building energy system, according to the preamble of patent claim 11, as well a method for absorbing and/or temporarily storing gas, in particular purge gas discharged during a purge process, according to the preamble of patent claim 13.

Energy systems of the generic type are already known in many ways in the prior art. Such systems usually generate and provide energy for a wide variety of application areas.

In a known type of such energy system, electrical energy is converted into chemical energy for storage. Hydrogen, for example, can be used as an energy source. The hydrogen is produced, for example, in an electrolysis device and stored in a storage device. This is, for example, a first mode of operation of the energy system. During operation of the energy system, the hydrogen is removed from the storage device and consumed in an energy sink device. This is, for example, a second mode of operation of the energy system. Such an energy sink device is, for example, a fuel cell device. The above-described components of the energy system are usually spatially separated from one another and connected to one another via a connecting line device. Both of the aforementioned operating modes usually require different pressure levels. While pressures of 20 to 60 bar prevail in the first operating mode with electrolysis, for example as a starting situation for storage at increased pressure, pressures of less than 20 bar are advantageous for operating the fuel cell device in the second operating mode.

As part of the operation of such an energy system, it is necessary to regularly flush the fuel cell device, in particular on its anode side, and/or the electrolysis device, in particular on its cathode side. Flushing, which is also referred to as “purging” in the following, is particularly necessary to remove unwanted foreign gas components and liquid water that accumulates locally in the cell structures, which can negatively influence the performance and lifespan of the fuel cell device and/or the electrolysis device. to be dissipated at regular intervals or depending on the operating conditions. Rinsing is carried out using a suitable rinsing system.

A known flushing system on which the present invention is based is in the EP 3 380 652 B1 disclosed and described by the applicant. In this known solution, a flushing gas volume flow loaded with hydrogen is generated during the flushing process and initially stored in a storage chamber. The storage chamber serves as a buffer storage or as a temporary storage. From the storage chamber, the purge gas volume flow loaded with hydrogen is then released into the environment as a discharge volume flow via an outflow device. The storage chamber is an expandable storage chamber, which is designed as a piston accumulator. This storage chamber has a first piston storage element designed as a liquid chamber, into which liquid is filled. Furthermore, the storage chamber has a second piston storage element designed as a reciprocating piston element, the piston storage elements being inserted into one another in opposite directions, and the piston storage elements being axially movable relative to one another. The first piston accumulator element is external to the second piston accumulator element. The storage chamber also has a gas inlet line and a gas outlet line.

The purging gas volume flow discharged during the purging process must not be released to the outside in an uncontrolled manner, otherwise an explosive zone can form. It is therefore necessary that the gas temporarily stored in the storage chamber, which is purge gas or "purge gas", is released to the outside in a controlled manner.

Storage devices for storing gas are also known in a different form in the field of large-scale industrial systems. Here the storage facilities serve as gas storage facilities for storing large quantities of gas, up to 100,000 m ³ . Such large gas storage facilities are often referred to as gasometers. For safety reasons, the gas is stored at normal pressure or at pressures less than or equal to atmospheric pressure. Such a large gas storage facility is, for example, in the US 1894,536 B described. This known gas accumulator is also designed as a piston accumulator, consisting of a first, static piston accumulator element and a second movable reciprocating piston accumulator element, the piston accumulator elements being inserted into one another in opposite directions, and the piston accumulator elements being axially movable relative to one another. In order to be able to operate the large gas storage tank at normal pressure, the reciprocating piston element has support so that it can be moved at all. This support consists of weights attached to ropes. By means of deflection rollers, the wipers are attached to the movable reciprocating piston element in such a way that the weights move in the direction of the container bottom of the first piston storage element due to the weight force, whereby the movable reciprocating piston element is lifted and moves upwards.

In contrast, the one in the EP 3 380 652 B1 The storage device described, as well as the storage device according to the invention, is a small-scale system. However, the principles that apply to large-scale systems cannot easily be transferred to such small-scale systems. The sizes of the components, as well as the amounts of stored gas, are much smaller in small-scale systems than in large-scale systems, so that completely different physical relationships and requirements prevail here.

The present invention is therefore based on the object of further advantageously modifying and optimizing a generic storage device, which is designed in particular for an energy system, i.e. a small-scale system, for the purposes of a controlled release of gas, by means of structurally simple and cost-effective measures.

This object is achieved according to the invention by the storage device with the features according to independent claim 1, which represents the first aspect of the invention, by the energy system with the features according to the independent Claim 11, which represents the second aspect of the invention, and by the method having the features according to independent claim 13, which represents the third aspect of the invention. Further features and details of the invention emerge from the subclaims, from the description and from the drawings. Features and details that are disclosed in connection with the first aspect of the invention also apply in full in connection with the second and third aspect of the invention, and vice versa, so that with regard to the disclosure of one of the aspects of the invention, full reference is always made to the other aspects of the invention and this is referred to.

The invention is initially directed to a storage device. The storage device is preferably part of an energy system. The energy system is, in particular, a whole consisting of several components, with the components being connected to one another to form a dedicated unit. In the present case, the energy system is preferably a system for generating or providing energy, preferably electrical energy. In principle, the invention is not limited to certain types of energy systems. Various preferred exemplary embodiments are described below in this regard.

In a preferred embodiment, the energy system is a building energy system. Building energy systems are generally known from the prior art and are used to supply buildings, for example low-energy buildings, passive buildings or zero-energy buildings, with energy in the form of heat and in particular in the form of electricity, for example electricity from renewable energy sources such as photovoltaic (PV) generators or small wind turbines. Such a building energy system creates the basis for the energy requirements of a building, both in terms of electricity and heat requirements, to be completely covered by renewable energy sources and thus to be completely CO ₂ -free during operation. But at least the electricity requirements of a building can be covered almost entirely from renewable energy sources, in particular by means of a PV generator and/or a small wind turbine, in the sense of increasing self-consumption.

Such a building energy system is, for example, in the patent applications WO 2017/089468 A1 and WO 2017/089469 A1 disclosed and described by the applicant, the disclosure content of which is included in the description of the present patent application.

• einen DC-Einspeisepunkt, bevorzugt ausgebildet für eine Nenn-Spannung von 48 Volt oder für eine Nennspannung zwischen 200 und 1000 Volt und/oder einem AC-Einspeisepunkt, bevorzugt ausgebildet für eine Spannung von 230 Volt oder 110 Volt oder einer 3-phasigen Einspeisung bei pro Phase 230 Volt oder 110 Volt, wobei der DC-Einspeisepunkt und/oder der AC-Einspeisepunkt im Betrieb zumindest zeitweise mit einem elektrischen Verbraucher, der eine Verbrauchs-Leistung aufweist, verbunden ist,
• einen elektrisch mit dem DC-Einspeisepunkt wenigstens zeitweise verbundenen PV-Generator zum Erzeugen einer elektrischen PV-Leistung,
• eine elektrisch mit dem DC-Einspeisepunkt oder mit dem AC-Einspeisepunkt wenigstens zeitweise verbundene Brennstoffzelleneinheit zum Erzeugen einer elektrischen Brennstoffzellen-Leistung,
• eine elektrisch mit dem DC-Einspeisepunkt oder mit dem AC-Einspeisepunkt wenigstens zeitweise verbundene Elektrolyseeinheit zum Erzeugen von durch die Brennstoffzelleneinheit zu verbrauchendem Wasserstoff, wobei die Elektrolyseeinheit im Betrieb mit einer elektrischen Elektrolyse-Eingangsleistung gespeist wird,
• einen Wasserstofftank, insbesondere als Langzeitenergiespeicher, der mit der Brennstoffzelleneinheit und der Elektrolyseeinheit wenigstens zeitweise fluidverbunden ist und zum Speichern von mittels der Elektrolyseeinheit zu erzeugendem und durch die Brennstoffzelleneinheit zu verbrauchendem Wasserstoff ausgebildet ist,
• eine Speicher-Batterieeinheit, insbesondere als Kurzzeitenergiespeicher, die elektrisch mit dem DC-Einspeisepunkt oder über einen vorzugsweise bidirektionalen Wechselrichter mit dem AC-Einspeisepunkt wenigstens zeitweise verbunden oder zu verbinden ist, so dass eine elektrische PV-Leistung und eine elektrische Brennstoffzellen-Leistung in die Speicher-Batterieeinheit eingespeichert werden kann und eine elektrische Elektrolyse-Eingangsleistung und eine Verbrauchs-Leistung aus der Speicher-Batterieeinheit entnommen werden können; und
• ein Steuermodul zum Steuern der Gebäudeenergieanlage.

According to a preferred embodiment, a building energy system of the type mentioned has the following basic features:

• a DC feed point, preferably designed for a nominal voltage of 48 volts or for a nominal voltage between 200 and 1000 volts and / or an AC feed point, preferably designed for a voltage of 230 volts or 110 volts or a 3-phase feed 230 volts or 110 volts per phase, the DC feed point and/or the AC feed point being connected at least temporarily during operation to an electrical consumer that has a consumption output,
• a PV generator that is electrically connected to the DC feed point at least temporarily to generate electrical PV power,
• a fuel cell unit electrically connected to the DC feed point or to the AC feed point at least temporarily for generating electrical fuel cell power,
• an electrolysis unit electrically connected at least temporarily to the DC feed point or to the AC feed point for generating hydrogen to be consumed by the fuel cell unit, the electrolysis unit being fed with an electrical electrolysis input power during operation,
• a hydrogen tank, in particular as a long-term energy storage device, which is at least temporarily fluidly connected to the fuel cell unit and the electrolysis unit and is designed to store hydrogen to be produced by the electrolysis unit and consumed by the fuel cell unit,
• a storage battery unit, in particular as a short-term energy storage device, which is electrically connected or is to be connected at least temporarily to the DC feed point or via a preferably bidirectional inverter to the AC feed point, so that an electrical PV power and an electrical fuel cell power are in the Storage battery unit can be stored and an electrical electrolysis input power and a consumption power can be removed from the storage battery unit; and
• a control module for controlling the building energy system.

The basic idea of the present invention is to provide a specially designed storage device for gas. The gas is in particular hydrogen or a gas containing hydrogen, and therefore an explosive gas if the gas mixture contains an oxygen content of more than 4 percent by volume, even temporarily. Any kind of ignition sources within the storage device must therefore be strictly avoided. This occurs in particular during a flushing process, which is also referred to below as a “purge process”. The operation of the fuel cell device and the electrolysis device requires cyclic cleaning of the reactive surfaces of, among other things, nitrogen and water. Cleaning or rinsing is also referred to below as “purging”. Cleaning is preferably carried out using a pressure surge. A purge process can also make sense if the operating pressure of the fuel cell or electrolysis needs to be quickly relaxed to a lower pressure, for example as part of controlled shutdown processes. At operating pressure, which is around 350 mbar for fuel cells and around 30 bar for electrolyzers, a respective purge valve is briefly opened against the atmosphere. The resulting pressure difference across the purge valve generates a gas volume flow that discharges reaction-inhibiting substances and is transported into the storage device used by the fuel cell and the electrolyzer, preferably dual. The discharged moist purge gas must not be released outside in an uncontrolled manner, for example into the environment or into a system cabinet, otherwise an explosive zone can form. However, controlled release can occur through permanent technical ventilation, in particular at least 100 m ³ /h. For this purpose, the purge gas must be collected in the storage device, which is in particular a buffer storage or an intermediate volume, and then released from the storage device in a controlled manner.

The storage device is preferably a passive assembly for receiving/temporarily storing the flushing gas or purge gas.

If the storage device is used for such an energy system, it is in particular a small-scale system in the above sense. The knowledge known from the field of large-scale technical systems can be drawn from the above Therefore, for reasons not easily transferred to the storage device according to the present invention.

According to the first aspect of the invention, a storage device for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, is provided, which has the features of independent claim 1.

The storage device has an expandable, that is to say a volume-variable, storage chamber.

This storage chamber is designed as a piston accumulator. A piston accumulator is in particular a memory which has at least two piston accumulator elements which interact with one another, with at least one of the piston accumulator elements being movable, preferably axially movable. The piston storage elements form or delimit in particular a closed hollow space, the volume of which changes as a result of the movement.

The storage device according to the invention has a first piston storage element designed as a liquid chamber, into which liquid, for example in the form of water, can be filled up to a defined liquid level or into which liquid, for example in the form of water, is filled up to a defined liquid level. When the storage device is used as intended, the liquid is located in the first piston storage element. The liquid level is in particular a defined height up to which liquid may be filled or up to which liquid is filled during proper operation. This height must be maintained for proper operation. According to one embodiment, the amount of liquid to be held in the liquid chamber is less than 50 liters, preferably between 1 and 5 liters.

The first piston accumulator element preferably has a base element and a side wall projecting from the base element. At the free end of the side wall, which lies opposite the base element, the first piston accumulator element is preferably open. Carried liquid drops from the stored purge gas are deposited into the first piston storage element.

Furthermore, the storage chamber has a second piston storage element designed as a reciprocating piston element. The second piston accumulator element preferably has a base element and a side wall projecting from the base element in the direction of the first piston accumulator element. At the free end of the side wall, which lies opposite the base element and which faces the first piston accumulator element, the second piston accumulator element is open. With respect to the entire storage chamber consisting of the first and second piston storage element, the base element of the second piston storage element represents a cover element of the storage chamber.

In one embodiment, the second piston storage element has a gas volume for gas to be absorbed of less than 10 liters, preferably less than 5 liters, preferably between 0.5 liters and 3 liters. The gas volume is in particular the volume that is or may be introduced into the second piston storage element when the storage device is used as intended. The gas volume is, in particular, the useful volume. The useful volume indicates the maximum amount of gas that can be stored in the second piston storage element. This means that the storage device differs fundamentally from the storage devices in the form of large-scale systems. As will be explained in more detail below, the deflection of the reciprocating piston element occurs solely due to the gas inlet. Due to the small volume that the reciprocating piston element has, the pressure of the gas to be stored alone is sufficient to deflect the reciprocating piston element. In contrast to large-scale systems, the deflection in the storage device according to the invention occurs in particular due to a gas pressure that is above atmospheric pressure. In addition, the deflection occurs without the aid of external forces such as counterweights, motors or spring forces. This means that the second piston storage element is provided for deflection due to the gas fed in.

The first piston accumulator element and the second piston accumulator element are preferably matched to one another in terms of their size, geometry, contour and capacity.

The transition between the base element and the side wall of the second piston accumulator element preferably has rounded corners or edges. If in the If condensate accumulates in transition areas, in particular in the corner areas or edge areas, this will definitely be drained away, preferably into the liquid located in the first piston accumulator element.

The two piston accumulator elements are, in particular concentric, inserted into one another in opposite directions and are axially movable relative to one another. In one embodiment, the first piston storage element is fixed, that is, immovable, while the second piston storage element is movable. Of course, constellations are also conceivable in which both piston accumulator elements are movable, or only the first piston accumulator element.

In the first-mentioned, preferred embodiment, the second piston storage element is deflected by the release of purge gas from the fuel cell device and/or the electrolysis device. The counterpressure resulting from the deflection, in particular caused by the weight of the second piston accumulator element, must not impair the dynamics and pressure ratio of the purge process. Due to the weight of the second piston accumulator element, the purge gas is pushed out of the second piston accumulator element again after the deflection has ended, as will be described in more detail below.

In a first operating state, which is also referred to as the rest state, the storage chamber is not expanded. For example, the second piston accumulator element is not deflected. In a second operating state, which is also referred to as a storage state, the storage chamber is in an expanded state. For example, the second piston storage element is deflected due to the stored purge gas. While the first operating state is preferably a static state, the second operating state is preferably a dynamic state.

In one embodiment, the first piston accumulator element and/or the second piston accumulator element is/are designed to be monolithic, that is to say consisting of one piece. The gas space in which the purge gas is/is stored is therefore separated from the environment by a coherent, one-piece geometry and, as will be explained in more detail below, is only supplied by the liquid in the first piston accumulator element poetic. Thanks to this design, the bearings of the second piston accumulator element are also sealed outside the gas space and always via the liquid.

Preferably, the first piston accumulator element and/or the second piston accumulator element is/are cup-shaped or cylindrical. A cup-shaped piston storage element is in particular a vessel that is open at the top and closed on the sides and bottom for holding liquid and/or gas. For example, such a vessel can be cylindrical.

Preferably, the first piston accumulator element and the second piston accumulator element are designed to be rotationally symmetrical.

In order to introduce gas into and discharge gas from the second piston storage element, the storage device has a gas inlet line and a gas outlet line, which open into the storage chamber. Purge lines of the fuel cell device and the electrolysis device converge in the gas inlet line. In this way, the storage device can be used either to store purge gas from the fuel cell device or the electrolysis device.

According to the invention, the first piston accumulator element is external in relation to the second piston accumulator element. This means in particular that the side wall of the first piston accumulator element at least partially surrounds the side wall of the second piston accumulator element.

A gap, in particular a circumferential gap, is formed between an outer surface, in particular the side wall or part of the side wall, of the second piston accumulator element and an inner surface, in particular the side wall or part of the side wall, of the first piston accumulator element. If there is liquid in the first piston accumulator element and the second piston accumulator element is inserted into the first piston accumulator element in the manner described above, there will therefore also be liquid in the gap.

In a preferred embodiment, the volume of liquid in an internal volume of the second piston accumulator element is in a defined ratio to the volume of liquid in the gap between the first and second piston accumulator elements.

The main reason for this is that a seal formed by the liquid is balanced. This will be explained in more detail below in connection with a sealing device. Preferably the ratio is greater than or equal to 3:1, preferably greater than 5:1. A volume ratio defined in this way also has a significant influence on oscillation/settlement after the purge.

According to the invention, it is further realized that the gas inlet line and the gas outlet line end above the defined liquid level for the liquid in the second piston storage element. This means that the mouth, i.e. the end, of the gas inlet line and the gas outlet line protrude above the liquid level or beyond the liquid located in the first piston accumulator element. The stored gas is thus stored in a liquid-free gas space, which is located in particular in the second piston storage element. This means that there is no liquid displacement when the flushing gas is introduced, which reduces the back pressure during flushing. The lower the back pressure, the better the cleaning can be done. This is because a reduced back pressure during flushing can make the discharge of reaction-inhibiting media, such as nitrogen, water, and the like, from the fuel cell device and/or electrolysis device more effective, shorter and therefore more efficient. The design according to the invention creates a counterpressure that hardly increases during the purge, since, for example, the spring constant of a bellows is eliminated and the mouth of the gas inlet line protrudes above the liquid level. There is therefore no displacement of water when the flushing gas is introduced. Reduced back pressure during flushing can make the discharge of reaction-inhibiting media such as nitrogen, water and the like from the fuel cell or electrolysis more effective, shorter and therefore more efficient.

In the flushing device according to the invention, the counterpressure is preferably created solely by the weight of the second piston accumulator element. By introducing purge gas into the second piston accumulator element, the second piston accumulator element is deflected. The counterpressure created by the deflection, resulting from the weight of the second piston accumulator element and from the dynamic inertia force of the second piston accumulator element, which was initially accelerated during the purging process, must not impair the dynamics of the purging process and the pressure ratio. After the gas introduction has ended, the deflection of the second piston accumulator element stops, and the flushing gas is released by the weight of the second piston accumulator element after the end of the gas introduction Deflection pushed out again through the gas outlet line. As a result, the second piston accumulator element lowers again in the direction of the first piston accumulator element.

In one embodiment, the storage device is assigned a control device. A control device is in particular the entirety of all components that influence the storage device. The control device can be designed in the form of hardware components or software components, or as a combination thereof. In particular, the control device has a processor device in which at least parts of the method according to the invention run according to the third aspect of the invention. The control device preferably has interfaces to various components of the storage device, for example to valve devices and/or sensor devices. Depending on the design, the control device is at least partially part of the storage device. Or the control device is a component external to the storage device, which is then connected and communicates at least temporarily, for example wirelessly or wired, via the interfaces with the storage device. In one embodiment, the control device is a component, or even the control device itself, of an energy system, such as the energy system according to the second aspect of the invention.

Via the gas inlet line, the purge gas is introduced into the second piston storage element above the liquid level, that is, above the liquid level, in any case, at least briefly, above or above the liquid surface.

For this purpose, the gas inlet line preferably has a valve device on the inlet side. This valve device is preferably at least temporarily connected to the control device via an interface.

In order to release the gas stored in the storage chamber in a controlled, time-delayed manner and with a significantly reduced gas mass flow, in addition to the measures described above, it is preferably implemented that the gas outlet line has a metering device or a throttle element or a diaphragm and/or a filter element on the outlet side. In this way, the discharged moist purge gas is prevented from being released into the environment, for example into a system cabinet, without being throttled. Instead, the delivery can be done in doses. Delivery preferably takes place without an actively controlled valve or control.

The first piston storage element preferably has a liquid inlet and/or a liquid outlet. This can be a single component or two separate components. In the former case, this interface is used bidirectionally in the first piston accumulator element to fill and empty.

To ensure that the aforementioned components are not contaminated with possible contaminants or deposits, a filter element is preferably used.

The inventive design of the storage chamber ensures in particular that liquid in the first piston storage element seals the buffer volume created by deflection of the second piston storage element from the environment. Drops of water carried along from the fuel cell device or the electrolysis device are separated here before the purge gas is released through the metering device, the throttle element or the aperture to the outside, for example into a system air stream. The second piston accumulator element is cyclically emptied and refilled to remove any residue or excess liquid. Newly added liquid is preferably cleaned via a filter device, for example an osmosis membrane, in order to exclude limescale deposits, for example. The liquid level is preferably measured via a sensor element, as will be explained in more detail below.

Due to the inventive design of the storage device, in particular the storage chamber, the flushing gas for storage does not enter the liquid located in the first piston storage element, but rather into a space above it in which there is no liquid. Aerosols or droplets carried along are discharged by deflection and changing the flow velocity and are preferably separated gravimetrically and/or, if the purge gas is introduced with a tangential component, via centrifugal forces before the purge gas enters the gas outlet line. Delivery is preferably carried out without a valve or control.

Preferably, the gas inlet line and the gas outlet line are guided anti-parallel with respect to the gas flow path.

In a preferred embodiment, the gas inlet line and the gas outlet line are guided from below through the first piston accumulator element, in particular through its base element, into the second piston accumulator element.

The invention is not limited to specific embodiments for the second piston accumulator element. In a simple embodiment, the second piston accumulator element has a flat, straight or horizontally extending base element, from which the side wall projects, preferably perpendicularly or vertically, in particular in the direction of the first piston accumulator element, in particular in the direction of the base element of the first piston accumulator element. In another embodiment, the base element of the second piston accumulator element can, for example, be curved and, for example, have a dome-like or dome-like configuration. It is also not necessary for the side wall of the second piston accumulator element to project vertically from its base element. It is also conceivable that the side wall protrudes from the base element at an angle, or that the side wall has a curved course.

In a preferred embodiment, the second piston accumulator element has a first portion which faces a base element of the first piston accumulator element. In addition, the second piston accumulator element has a second portion which faces away from the base element of the first piston accumulator element. In this embodiment, the first partial area is designed differently than the second partial area, so that the height of the second piston accumulator element changes. It is preferably realized that the volume of the second subregion is smaller than the volume of the first subregion, and/or that the cross-sectional area of the second subregion is smaller than the cross-sectional area of the first subregion. In this case, the second piston accumulator element has a step-shaped course in its height extent.

In the selected embodiment of the first and second piston storage element, it is preferred that the dead volume, in which there is no liquid, and into which the purging gas reaches for the purpose of storage, is in the idle state of the storage chamber in which it is not expanded, in particular when the second Piston accumulator element is not deflected is as low as possible. By designing the second piston accumulator element with the two partial areas, the dead volume can be further reduced. In one embodiment, this dead volume is less than 10% of the total volume of the second piston storage element. In particular, the dead volume is preferably between 0.1 liter and 1 liter.

If the second piston storage element has a base element and a side wall projecting from the base element in the direction of the first piston storage element, the gas inlet line is in a non-expanded state, that is to say in the rest state, of the storage chamber, in which the second piston storage element is not expanded in relation to the first piston storage element and the gas outlet line in a preferred embodiment immediately in front of the base element of the second piston accumulator element. These preferably end in its second section. This means that the gas inlet line and the gas outlet line end in the idle state just below the floor element at a short distance from the floor element. The distance can vary depending on the design and dimensioning of the piston accumulator elements, in particular the second piston accumulator element, and/or with regard to the quantities of gas to be stored and is preferably in the range of a few millimeters to a few centimeters. In particular, the distance is preferably between 1mm and 5mm. This also keeps the dead volume described above low.

The purge gas entering via the gas inlet line above the liquid hits the bottom element of the second piston storage element, which in this case also represents a cover element of the storage chamber. As a result, on the one hand, the second piston accumulator element is deflected. At the same time, the gas is diverted at the base element. In a preferred embodiment, it is therefore realized that when the gas is introduced into the second piston accumulator element, it is directed against the base element of the second piston accumulator element and is deflected from there before it enters the gas outlet line and is derived from there from the second piston accumulator element. Droplets and aerosols in the gas stream are separated and at the same time the flow speed of the gas is reduced. Additional upstream components are not required. The design is very robust and also leads to a saving in installation space.

In a preferred embodiment, the storage device has a sealing device for sealing the gap against the atmosphere between the first piston storage element and the second piston storage element. This results in a sealing of the storage chamber designed as an expandable piston accumulator, or the Gas volume during purging compared to the surrounding atmosphere. In this way, the storage chamber is robust against the entry of moisture and robust, error-free operation of the storage device is guaranteed. In a preferred embodiment, the sealing device is/is formed by liquid filled into the first piston accumulator element. The liquid in the first piston accumulator element, and in particular in the gap between the first and second piston accumulator element, seals the buffer volume created by deflection of the second piston accumulator element from the environment, for example a system cabinet. This liquid seal is preferably balanced in a special way, for example by providing the volume ratios of liquid described above between the internal volume of the second piston accumulator element and the gap volume between the first and second piston accumulator element.

Alternatively or additionally, the storage device preferably has an overpressure protection, which is preferably formed by the gap between the first piston storage element and the second piston storage element. This overpressure protection is illustrated using an example. For example, a quantity of purge gas flows into the second piston storage element through the gas inlet line, for example by opening a valve, for approximately 300 ms. During proper operation, a "normal" deflection occurs, in particular of the second piston accumulator element, which is detected, for example, with a sensor element. At the end of the inflow process, the valve is closed. During proper operation, the pressure slowly reduces via the gas outlet line. The overpressure protection is a type of automatically acting safety mechanism, for example if the valve does not close or does not close properly and the second piston accumulator element has reached its maximum deflection, or if the second piston accumulator element tilts. In these cases, the gas pressure in the second piston accumulator element increases. This causes the water column to be displaced downwards. The water column in the gap between the first and second piston storage elements naturally increases at the same time. Water and the gas contained therein “bubble” outwards through the open end of the gap. This prevents the storage chamber from bursting.

Alternatively or additionally, the first piston storage element preferably has a protective outlet in a side wall, below the end of the gas inlet line and the gas outlet line. This protective outlet protects the gas inlet line and the gas outlet line from filling up with liquid in the event of a fault. The The height of the protective outlet is preferably between the defined liquid level of liquid and the ends of the gas inlet line and the gas outlet line.

In order to be able to monitor the proper operation of the storage device, a series of sensor elements are preferably provided, which are described in more detail below. Depending on requirements, the sensor elements, at least individual sensor elements, can be connected to the control device via suitable interfaces.

The storage device preferably has at least one sensor element for determining the pressure in the gas outlet line. In particular, the internal pressure in the storage chamber, in particular in the second piston storage element, can be determined in this way. The gas is released from the storage chamber preferably without a valve or control and is throttled to the system air, for example by a diaphragm or another metering device or a throttle element. Between the buffer volume and the aperture there is preferably a pressure measuring point in the form of the sensor element mentioned, which represents the internal pressure of the storage chamber with sufficient accuracy.

The storage device preferably has at least one sensor element for determining the position of the second piston storage element. The sensor element is preferably a contactless and/or capacitive sensor element. The height or deflection of the second piston accumulator element can be determined and determined via this sensor element. In particular, the nominal height up to which the second piston accumulator element may be deflected by storing purge gas, or whether the second piston accumulator element has reached this nominal height, can also be determined.

The storage device preferably has at least one sensor element for measuring the liquid level in the first piston storage element. For example, a further sensor element can also be provided which measures the liquid height in the gap between the first and second piston accumulator elements. The sensor element(s) is preferably a contactless and/or capacitive sensor. The sensor element is used to determine in particular whether the liquid is in the area of the defined liquid level. Is the recorded one If the liquid level is above or below, the liquid inlet or outlet can be activated in a suitable manner.

As already described above, according to the invention it is realized that the first piston accumulator element is axially movable against the second piston accumulator element. In a preferred embodiment, the first piston accumulator element is fixed, i.e. immovable, while the second piston accumulator element is movable, i.e. deflectable. In a preferred embodiment, the storage device has a guide device, in particular a linear guide device, for the second piston storage element for the axial mobility of the first piston storage element relative to the second piston storage element. Such a guide device is particularly free-moving, robust and does not lead to any intervention in the overall system. No fixed bearings are required, especially with a linear guide. This leads to the smallest possible transverse forces and prevents the use of flexible materials. This increases the lifespan of the storage device.

By means of the guide device, the second piston storage element slides upwards, preferably linearly, when purge gas is absorbed and preferably triggers a sensor element for determining the position at a defined deflection. The second piston accumulator element is preferably guided by at least one, preferably two plain bearings on a guide rod. The plain bearing is in particular a cylindrical plain bearing. The plain bearing is designed in particular in the form of a self-lubricating plastic bushing. The plain bearing is preferably ultrapure water-resistant, cycle-proof and suitable for the applied load. The guide rod is preferably surrounded by a hollow profile element, for example a tube, in particular a stainless steel tube, which represents the actual guide of the second piston accumulator element, and at each end of which there is a plain bearing. The guide rod runs through the hollow profile element, which is connected to the second piston accumulator element. The hollow profile element slides along the guide rod, whereby the second piston accumulator element is moved, in particular deflected. The guide rod is preferably mounted/fastened in the first piston accumulator element. The guide rod should not penetrate the first piston accumulator element to avoid potential leak points.

Preferably, the storage device has a frame device, which is arranged or formed in particular on the first piston storage element. The frame device serves in particular to support and support the piston accumulator elements and the guide rod of the guide device. The storage device can also be mounted on other components of an energy system, for example in a system cabinet, via the frame device. Preferably, the guide device, in particular the guide rod of the guide device, is part of the frame device.

In a preferred embodiment, the second piston accumulator element has one or more stabilization element(s), which is/are designed, for example, as a stabilization rib(s). The at least one stabilizing element is preferably arranged or formed on the outside of the base element of the second piston accumulator element and is preferably arranged at one end on the hollow profile element of the guide device or connected to it. The at least one stabilizing element serves in particular to secure the contour of the second piston accumulator element so that it does not deform or tilt. This ensures that the second piston accumulator element is always guided smoothly during its deflection movement. In addition, the second piston storage element, in particular its base element, is prevented from deforming if the gas pressure inside the storage chamber becomes too high.

In a further embodiment, the second piston accumulator element has at least one activation device for activating or triggering a sensor element as described above for determining the position of the second piston accumulator element. The activation device is designed, for example, in the form of an activation ring which is arranged or formed on the outside of the second piston accumulator element.

In a further embodiment, the storage device has a fastening device by means of which the storage device, in particular its storage chamber, can be fastened to a component of an energy system, for example on/in a system cabinet. The fastening device preferably has a number of different elements. For example, the fastening device can have at least one pin for fixing the position. This preferably projects downwards from the bottom element of the first piston accumulator element. The pen works with a corresponding Receiving opening together into which the pen is inserted. In this way, the storage device is brought into the desired/required position when it is attached. Furthermore, the fastening device preferably has at least one fastening element, by means of which the storage device, in particular the storage chamber, is arranged on an external component, for example on/in a system cabinet, preferably releasably. The fastening element is preferably a fastening bracket, which is made, for example, from sheet metal. The receiving opening for the pin described above can be formed in particular in the fastening element. The storage device, in particular the storage chamber, can be attached, preferably releasably, to the at least one fastening element via a fastening clamp or a fastening band. The fastening device makes it possible in a simple manner to fasten the storage device, in particular the storage chamber, and to dismantle it again if necessary, for example if an exchange is necessary.

According to the second aspect of the invention, an energy system, in particular a building energy system, is provided which has the features of independent patent claim 11. The energy system, which is designed in particular as a building energy system, has an electrolysis device, a fuel cell system, optionally a high-pressure storage device or another suitable storage device for hydrogen, in particular a medium-pressure storage device or a metal hydride storage device, and a connecting line device via which the electrolysis device, the fuel cell system and optionally the storage device are connected to each other.

According to the invention, the energy system is characterized in that it has at least one storage device for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, according to the first aspect of the invention. In order to avoid repetition, reference is made here in full to the statements on the storage device according to the first aspect of the invention as well as to the general description of the energy system above.

Preferably, the storage device is arranged in a first subsystem of the energy system. In particular, the storage device is in a, in particular ventilated, preferably arranged in a stationary system cabinet of the energy system. The storage device arranged in a system cabinet is thus protected from weather influences, for example from rain, frost, UV radiation, and the like. During operation, a constant volume of air flows through the system cabinet, for example at temperatures between 5°C and a maximum of 70°C. The purge gas temporarily stored in the storage device is preferably introduced into this air volume flow in a controlled manner, so that no undesirable, harmful ignition sources can arise.

According to the third aspect of the invention, a method is provided which has the features of independent claim 13. The method is used to absorb and/or temporarily store gas, in particular purge gas discharged during a purge process. Preferably, the method is carried out using a storage device according to the first aspect of the invention and/or in an energy system according to the second aspect of the invention. To avoid repetition, at this point, in particular with regard to how the method works, we also refer in full to the general description of the energy system above as well as to the comments on the storage device according to the first aspect of the invention and to the comments on the energy system according to the second aspect of the invention Referenced and referenced.

The method according to the invention takes place in an expandable storage chamber, which is designed as a piston accumulator, of a storage device. The storage chamber has a first piston storage element designed as a liquid chamber, into which liquid is filled up to a defined liquid level, and a second piston storage element designed as a reciprocating piston element, the piston storage elements being inserted into one another, in particular concentrically, aligned in opposite directions, the piston storage elements being axially movable relative to one another , and wherein the first piston accumulator element is external in relation to the second piston accumulator element and an, in particular circumferential, gap is formed between an outer surface of the second piston accumulator element and an inner surface (82) of the first piston accumulator element.

1. a) Über eine Gaseingangsleitung, die im zweiten Kolbenspeicherelement endet, wird Gas oberhalb des definierten Flüssigkeitslevels für die Flüssigkeit in das zweite Kolbenspeicherelement eingeleitet. Der Betrieb der Brennstoffzelleneinrichtung und der Elektrolyseeinrichtung erfordert ein zyklisches Spülen beziehungsweise Bereinigen der reaktiven Oberflächen von unter anderem Stickstoff und Wasser, beispielsweise durch einen Druckstoß. Vorzugsweise wird dazu ein jeweiliges Purgeventil gegen Atmosphäre kurz geöffnet. Die entstehende Druckdifferenz über das Purgeventil erzeugt einen Volumenstrom, der reaktionshemmende Stoffe austrägt und in die, vorzugsweise von der Brennstoffzelleneinrichtung und der Elektrolyseeinrichtung dual genutzte expandierbare Speicherkammer befördert. Durch den sich aufbauenden Gasdruck, insbesondere durch diesen allein, wird das erste Kolbenspeicherelement axial gegen das zweite Kolbenspeicherelement verschoben. Beispielsweise wird das zweite Kolbenspeicherelement, vorzugsweise mittels einer Führungseinrichtung, ausgelenkt, vorzugsweise bis zu einer definierten Nennhöhe beziehungsweise Nennauslenkung. Diese Auslenkung wird insbesondere durch den sich im zweiten Kolbenspeicherelement aufbauenden Überdruck, das heißt einen Druck oberhalb des Atmosphärendrucks, getrieben.

According to the invention, the method is characterized by the following steps:

1. a) Gas above the defined liquid level for the liquid is introduced into the second piston storage element via a gas inlet line that ends in the second piston storage element. The operation of the fuel cell device and the electrolysis device requires cyclic flushing or cleaning of the reactive surfaces of, among other things, nitrogen and water, for example by a pressure surge. For this purpose, a respective purge valve against the atmosphere is preferably opened briefly. The resulting pressure difference across the purge valve generates a volume flow that discharges reaction-inhibiting substances and transports them into the expandable storage chamber, which is preferably used dual by the fuel cell device and the electrolysis device. Due to the gas pressure that builds up, in particular due to this alone, the first piston accumulator element is displaced axially against the second piston accumulator element. For example, the second piston accumulator element is deflected, preferably by means of a guide device, preferably up to a defined nominal height or nominal deflection. This deflection is driven in particular by the excess pressure that builds up in the second piston accumulator element, that is, a pressure above atmospheric pressure.

Preferably, the gas is introduced into the second piston storage element per storage cycle for a defined period of time, for example for a period of less than a second, for example for 300 ms, and/or up to a defined nominal height of the second piston storage element. The nominal height can, for example, be a certain percentage of the maximum volume of the second piston element, for example a volumetric expansion of greater than 50%, for example 60%. The gas is introduced over a certain period of time, for example via a corresponding position of a valve device in the gas inlet line. The valve device is preferably controlled by means of the control device. Likewise, a sensor element for determining the position of the second piston accumulator element can forward the determined values to the control device via an interface. In one embodiment, the gas introduction is controlled solely based on the defined time period via a corresponding position of the valve device. In another embodiment, the gas introduction is controlled solely on the basis of the determined position determination, i.e. deflection, of the second piston accumulator element. In a third embodiment, the gas introduction is controlled based on a combination of the two previously described embodiments. This also allows possible errors to be detected and the valve to be closed if necessary. In the control device, the duration of the A period of time can be stored for how long gas is introduced into the second piston storage element of the storage device. At the beginning, the valve device is opened using the control device and closed again when the time period is reached. Alternatively or additionally, the position values of the second piston accumulator element detected by the sensor device are transmitted to the control device and evaluated there. Once a specified position value is reached, the valve for gas introduction is closed again. The control device generates suitable commands that are transmitted to the valve device and based on which the valve device is opened and closed again.
b) After the introduction of the gas has ended, for example after the purge valve has been closed, the deflection stops and the gas in the second piston storage element is discharged via the gas outlet line, which ends above the liquid level for the liquid in the second piston storage element, preferably solely by means of the weight of the second Piston storage element, discharged from the second piston storage element. This means that the weight of the second piston storage element pushes the purge gas outwards, for example into a system air flow, preferably through a defined aperture.

Preferably, when the gas is introduced into the second piston accumulator element with the effects described in the context of the first aspect of the invention, it is directed against a base element of the second piston accumulator element and is deflected from there before it enters the gas outlet line and is derived from there from the second piston accumulator element.

Preferably, the gas flow from the gas outlet line is adjusted by means of a metering device or a throttle element or an orifice, and/or the gas flow is filtered from the gas outlet line by means of a filter element, which is described in detail in connection with the first aspect of the invention. In this way, the purge gas discharged from the storage device, which is often still moist, is not unthrottled and is therefore released to the outside, for example into the system cabinet, with a gas volume flow leaving the piston storage element that is significantly reduced compared to the gas volume flow flowing into the piston storage element, which is why no explosive zone is formed can.

In order to be able to monitor the proper operation of the storage device, a series of sensor elements are preferably provided, the structure and functioning of which are explained in connection with the first aspect of the invention. The sensor elements preferably have suitable interfaces by means of which the measured values are transmitted to a sour device, for example a safety control device.

Figur 1

in schematischer Ansicht ein erfindungsgemäßes Energiesystem mit einer erfindungsgemäßen Speichervorrichtung;

Figur 2

den grundlegenden Aufbau eines ersten Ausführungsbeispiels der erfindungsgemäßen Speichervorrichtung;

Figuren 3 bis 8

verschiedene Betriebszustände einer Speichervorrichtung, insbesondere gemäß dem ersten Ausführungsbeispiel;

Figuren 9 und 10

den grundlegenden Aufbau sowie verschiedene Betriebszustände eines zweiten Ausführungsbeispiels der erfindungsgemäßen Speichervorrichtung.

The invention will now be explained in more detail using various exemplary embodiments with reference to the accompanying drawings. Show it

Figure 1

a schematic view of an energy system according to the invention with a storage device according to the invention;

Figure 2

the basic structure of a first exemplary embodiment of the storage device according to the invention;

Figures 3 to 8

different operating states of a storage device, in particular according to the first exemplary embodiment;

Figures 9 and 10

the basic structure and various operating states of a second exemplary embodiment of the storage device according to the invention.

The present invention relates to a storage device for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, the storage device being used in an energy system. The energy system is in particular a building energy system.

In Figure 1 The basic structure of the energy system 10 is first described.

How out Figure 1 As can be seen, the energy system 10 initially has a first subsystem 11, which is designed as an internal system. This means that the first subsystem 11 is located inside the building. The individual components of the first subsystem 11 are housed in a system cabinet 12 in the example shown. In addition, the energy system 10 has a second subsystem 13 in the form of an external system. This means that the second subsystem 13 is located outside the building.

The first subsystem 11 has an electrolysis device 14 for producing hydrogen. In addition, the first subsystem 11 has a fuel cell device 15. The second subsystem 13 also has a high-pressure storage device 21. The hydrogen produced in the electrolysis device 14 is stored in the high-pressure storage device 21 at up to 700 bar. In addition, the second subsystem 13 has a medium-pressure storage device 22 in which the hydrogen produced is temporarily stored at pressures between 20 and 60 bar before it is finally stored from there in the high-pressure storage device 21.

The individual components of the energy system 10 are connected to one another via a connecting line device 16, which consists of a number of different line sections. Individual line sections are designed as so-called bidirectional line sections.

The hydrogen produced in the electrolysis device 14 leaves the electrolysis device 14 via a line section of the connecting line device 16, in which, in the flow direction of the hydrogen produced, there is, for example, a check valve device 17 and subsequently a filter device 18 and a dryer device 19, in which the hydrogen produced is filtered and dried . The filter device 18 and the dryer device 19 can alternatively also be located in the second subsystem 13.

From the dryer device 19, the hydrogen generated flows via further line sections of the connecting line device 16 to a further check valve device 25 in the second subsystem 13. From there, the hydrogen generated reaches the medium-pressure storage device 22, which via a valve device 23, which is in particular as a check valve, for example in the form a solenoid valve, is formed, is connected to the connecting line device 17. A compressor device 24, in particular in the form of a piston compressor, is located in the connecting line device 16 in front of the high-pressure storage device 21. The hydrogen temporarily stored in the medium-pressure storage device 22 is stored in the high-pressure storage device 22 by actuating the compressor device 24.

This production process of the hydrogen up to its storage in the high-pressure storage device 21 represents a first mode of operation of the energy system 10. In this first mode of operation of the energy system 10, there is a pressure of 20 to 60 bar in the connecting line device 16. Such a pressure also exists in the medium-pressure storage device 22. The hydrogen removed from the medium-pressure storage device 22, which is an intermediate storage device, is compressed via the compressor device 24 to such an extent that it is stored in the high-pressure storage device 21 at pressures of up to 700 bar can be.

The hydrogen stored in the high-pressure storage device 21 is used to operate the fuel cell device 15. The operation of the fuel cell device 15 takes place in the second operating mode of the energy system 10. However, the fuel cell device 15 can only work at pressures of less than 20 bar. In the second mode of operation of the energy system 10, the hydrogen is removed from the high-pressure storage device 21 and expanded via an expansion device 26 in the form of a pressure reducer before it enters the fuel cell device 15. To measure the pressure, at least one pressure measuring device 20, for example in the form of a pressure sensor, is provided.

This in Figure 1 Energy system 10 shown represents a subarea of an overall building energy system, which is an electrically self-sufficient multi-hybrid building energy storage system based entirely on renewable energies.

The multihybrid building energy storage system makes it possible to distribute the electrical energy generated by a photovoltaic (PV) system, a small wind turbine or the like over the entire year based on demand. The system acts as an island system independent of the electrical network. Rather, the system is intended to ensure the building's electrical self-sufficiency, so that no electrical energy has to be drawn from the power grid throughout the year.

The primary task of the building energy system is to make the electrical energy obtained from photovoltaic (PV) modules or the like available to the consumer in the building. Secondarily, excess electrical energy can be temporarily stored in a short-term battery storage system during times of low load or high irradiation. Tertiary, the electrical energy can be stored in gaseous form in long-term hydrogen storage Hydrogen can be stored in the medium to long term for periods of low radiation such as night, winter or the like and made available again at any time as needed using fuel cells.

In addition to energy-related tasks, the system also functions as controlled living space ventilation using a built-in ventilation device.

The hydrogen produced in the electrolysis device flows via the hydrogen line into the pressure storage system installed outside.

If there is no or insufficient PV energy, energy is taken from the battery to cover the consumer load. If the energy stored in the short-term storage is not sufficient, the fuel cell device can cover the additional electrical energy requirements. In fuel cell operation, the hydrogen flows via the hydrogen line from the pressure storage system to the fuel cell device.

Simultaneous operation of the fuel cell device and the electrolysis device is excluded in regular operation, as this would make no sense in terms of energy. However, simultaneous operation for a very short period of time and for defined system conditioning purposes cannot be ruled out. The entire system is operated centrally via an Energy Manager with predictive energy management.

The second subsystem is in principle intended for operation outdoors, but under certain conditions can also be installed and operated within a specific area of the house.

During operation of the energy system 10, it is necessary for the electrolysis device 14 and the fuel cell device 15 to be flushed regularly, with the fuel cell device 15 being flushed in particular on the anode side and the electrolysis device 14 in particular on the cathode side. Flushing is particularly necessary in order to remove unwanted foreign gas components, as well as liquid water that accumulates locally in the cell structures, which can negatively influence the performance and service life of the fuel cell device 15 and/or the electrolysis device 14, at regular intervals or depending on the operating conditions.

Rinsing is carried out with the help of a rinsing system. The moist purging gas discharged during the purging process, which is also referred to as purge gas, must not be easily released to the outside, for example into the system cabinet 12, in particular not without being throttled, since otherwise an explosive zone can form. In order to enable controlled delivery, the discharged purge gas is collected in a storage device 40. For this purpose, the storage device 40, which is an expandable storage device 40 with an expandable storage chamber 41 in the form of a piston accumulator, is connected to the electrolysis device 14 via a first line section 27 and to the fuel cell device 15 via a second line section 28. As a result, the storage device 40 can optionally be used for temporarily storing purge gas from the electrolysis device 14 and the fuel cell device 15. From the storage device 40, the temporarily stored purge gas can then be given in a controlled manner into the system air flow 29, for example into the system cabinet 12 or outside.

Based on Figures 2 to 10 Various exemplary embodiments will now be described as to how a storage device 40 according to the invention can be designed.

The Figures 2 to 8 relate to a first embodiment of the storage device 40, while the Figures 9 and 10 a second embodiment of the storage device 40 relate.

In connection with Figure 2 The general structure of the memory device 40 according to the first exemplary embodiment will first be described. The Figures 3 to 5 show a first operating state of the storage device 40, which is a rest state in which the storage device 40 is not expanded. The Figures 6 to 8 show a second, operational operating state of the storage device 40, in which the storage device 40 is expanded.

According to the first exemplary embodiment, the storage device 40 has an expandable storage chamber 41 designed as a piston accumulator. The storage chamber 41 initially has a cylindrical or cup-shaped first piston storage element 42, consisting of a base element 43 and a side wall 44 projecting from it. The base element 43 and side wall 44 delimit Receiving volume 45, in which liquid 46 in the form of water is filled up to a defined liquid level 47. If necessary, liquid 46 can be admitted into or drained from the first piston accumulator element 42 via a liquid inlet/liquid outlet 63, which is used bidirectionally in the example shown. The level of liquid 46 in the first piston accumulator element 42 is measured via a sensor element 61 for measuring the level.

Furthermore, the storage chamber 41 has a second piston storage element 48 in the form of a reciprocating piston, which also has a base element 49 and a side wall 50. The second piston accumulator element 48 is also cylindrical or cup-shaped. Both the first piston accumulator element 42 and the second piston accumulator element 48 are open at their free ends of the side walls 45, 50, which lie opposite the respective base elements 43, 49, these openings facing one another. The two piston accumulator elements 42, 48 are monolithic and are concentrically and rotationally symmetrically aligned in opposite directions, inserted into one another and axially movable relative to one another.

In the first exemplary embodiment, the second piston accumulator element 48 is stepped in its height orientation and consists of a first, lower subregion 51 and a second, adjoining upper subregion 52, the first subregion 51 being larger in cross-sectional area than the second subregion 52. The floor element 49 has a corresponding, also step-shaped course. Between an outer surface 81 of the second piston accumulator element 48 and an inner surface 82 of the first piston accumulator element 42, which is particularly the case in the Figures 9 and 10 is shown for the second exemplary embodiment, but also applies analogously to the first exemplary embodiment, there is an annular circumferential gap 53, which is also filled with liquid 46.

The gas to be stored is introduced into the second piston storage element 42 and stored there via a gas inlet line 54, which is guided through the base element 43 of the first piston storage element 42 into the second piston storage element 48. It is provided that the upper end 55 of the gas inlet line ends above the defined liquid level 47, and thus in an area above the liquid 46, in the second piston accumulator element 48. The upper end 55 of the gas inlet line 54 is located in the immediate vicinity of the base element 49 of the second Piston storage element 48. In a similar manner, a gas outlet line 56 is also provided, via which the stored gas can be removed again from the storage chamber 41, in particular from the second piston storage element 48. The gas outlet line 56 is also guided through the base element 43 of the first piston accumulator element 42 into the second piston accumulator element 48. Here too it is provided that the upper end 57 of the gas outlet line 56 ends above the defined liquid level 47, and thus in an area above the liquid 46, in the second piston accumulator element 48. The upper end 57 of the gas outlet line 56 is located in the immediate vicinity of the base element 49 of the second piston accumulator element 48.

To ensure that the storage chamber 41 is sealed against the atmosphere so that stored gas cannot escape from the storage chamber 41 in an uncontrolled manner, the storage chamber 41 has a sealing device 58. This sealing device 58 is formed in a structurally simple manner by the gap 53 or by liquid 46 located in the gap 53. Depending on the design of the energy system, embodiments for the storage device 40 are also possible in which a corresponding seal can be dispensed with. In a similar way, the gap 53 also takes on the function of an overpressure protection 59. This overpressure protection and its functionality are explained in connection with the second exemplary embodiment according to Figures 9 and 10 described in detail, but is also valid in an analogous manner for the first exemplary embodiment described here.

In the side wall 45, the first piston storage element 42 has a protective outlet 60 below the end 55, 57 of the gas inlet line 54 and the gas outlet line 56. This protective outlet 60 protects the gas inlet line 54 and the gas outlet line 56 from filling up with liquid 46 in the event of a fault. The height of the protective outlet 60 lies between the defined liquid level 47 on liquid 46 and the ends 55, 57 of the gas inlet line 54 and the gas outlet line 56 .

In the first exemplary embodiment shown, it is realized that the first piston accumulator element 42 is fixed, that is to say immovable, while the second piston accumulator element 48 is movable, that is to say it can be deflected. The storage device 40 has a guide device 65 for the axial mobility of the second piston storage element 48 on, which is designed in the form of a linear guide. By means of the guide device 65, the second piston storage element 48 slides upwards, preferably linearly, when purge gas is absorbed and preferably triggers a sensor element 62 for determining the position at a defined deflection. The second piston accumulator element 48 is guided on a guide rod 76 by two plain bearings 75. The guide rod 76 is surrounded by a hollow profile element 66 in the form of a guide tube, which represents the actual guide of the second piston accumulator element 48, and at the ends of which the sliding bearings 75 are located. The guide rod 76 runs through the hollow profile element 66, which is connected to the second piston accumulator element 48. The hollow profile element 66 slides along the guide rod 76, whereby the second piston accumulator element 48 is moved, in particular deflected. The guide rod 76 is stored/fastened in the first piston accumulator element 42.

The storage device 40 has a frame device 64 which is arranged on the first piston storage element 42. The frame device 64 serves to support and store the piston accumulator elements and the guide rod 76 of the guide device 65.

According to the first exemplary embodiment, it is realized that the gas inlet line 54 and the gas outlet line 56 end above the defined liquid level 47 for the liquid 46 in the second piston storage element 48. The stored gas is thus stored in a liquid-free gas space, which is located in the second piston storage element 48. Gas above the defined liquid level 47 is introduced into the second piston storage element 48 via the gas inlet line 54. The operation of the fuel cell device 15 and the electrolysis device 14 (see Figure 1 ) requires cyclic flushing or cleaning of the reactive surfaces of, among other things, nitrogen and water, for example through a pressure surge. For this purpose, a respective purge valve against the atmosphere is preferably opened briefly. The resulting pressure difference across the purge valve generates a volume flow that discharges reaction-inhibiting substances and transports them into the expandable storage chamber 41, which is preferably used dual by the fuel cell device 15 and the electrolysis device 14. As a result of the gas pressure that builds up, the second piston accumulator element 48 is deflected by means of the guide device 65, preferably up to a defined nominal height or nominal deflection, which is detected via the sensor element 62.

Preferably, the gas is introduced into the second piston storage element 48 for a defined period of time, for example for 300 ms, and/or up to a defined nominal height of the second piston storage element 48 per storage cycle.

After the introduction of the gas has ended, for example after closing the purge valve, the deflection stops and the gas located in the second piston accumulator element 48 is discharged from the second piston accumulator element 48 via the gas outlet line 56, preferably solely by means of the weight of the second piston accumulator element. This means that the weight of the second piston storage element 48 pushes the stored purge gas outwards, for example into a system air flow.

When the gas is introduced into the second piston accumulator element 48, it is directed against the bottom element 49 of the second piston accumulator element 48 and is deflected from there before it enters the gas outlet line 56 and is derived from there from the second piston accumulator element 48.

In the Figures 3 to 5 a first operating state of the storage device 40 is shown, in which the storage chamber 41 is not expanded. In the Figures 6 to 8 a second operating state of the storage device 40 is shown, in which the storage chamber 41 is expanded due to the stored gas.

How to do that in particular Figures 5 and 8th can be seen, the second piston accumulator element 48 has a series of stabilizing elements 69 in the form of stabilizing ribs on its outside of the base element 49. Furthermore, the second piston accumulator element 48 has an activation device 74 in the form of an activation ring for activating or triggering the sensor element 62 for determining the position of the second piston accumulator element 48. In addition, the storage device 40 also has a fastening device 70, by means of which the storage device 40, in particular its storage chamber 41, can be attached to a component of an energy system 10, for example on/in a system cabinet. The fastening device 70 preferably has a number of different elements. For example, the fastening device can have at least one pin 71 for fixing the position. This projects downwards from the bottom element 43 of the first piston accumulator element 42. Furthermore, the Fastening device 70 has at least one fastening element 72 in the form of a fastening bracket, by means of which the storage device 40, in particular the storage chamber 41, is arranged on an external component, for example on/in a system cabinet, preferably releasably. The storage device 40, in particular the storage chamber 41, is releasably attached to the at least one fastening element 72 via a fastening clamp 73.

In the Figures 9 and 10 a second exemplary embodiment of the storage device 40 is shown. In terms of its basic structure and its mode of operation, the storage device 40 of the second exemplary embodiment corresponds to the storage device of the first exemplary embodiment, so that identical components are provided with identical reference numerals. Likewise, the disclosure of the first exemplary embodiment can also be applied to the disclosure of the second exemplary embodiment, and vice versa. Some features of the storage device 40 and their functionality are either only explained in connection with the first or second exemplary embodiment, but are also applicable to the other exemplary embodiment. The two exemplary embodiments differ in that the second piston accumulator element 48 is each designed differently. In the first exemplary embodiment Figures 2 to 8 the second piston accumulator element 48 is designed in a step-shaped manner, consisting of two different partial areas 51, 52, with a correspondingly step-shaped base element 49. In the second exemplary embodiment according to Figures 9 and 10 the second piston accumulator element 48 has a flat, horizontally oriented base element 49 and a side wall 50 projecting vertically therefrom. Furthermore, in the Figures 9 and 10 some features presented in the Figures 2 to 8 are not explicitly shown, but can also be applied in an analogous manner to the first exemplary embodiment.

According to the second exemplary embodiment, the storage device 40 also has an expandable storage chamber 41 designed as a piston accumulator. The storage chamber 41 has a cylindrical or cup-shaped first piston storage element 42, consisting of a base element 43 and a side wall 44 projecting from it. Base element 43 and side wall 44 delimit a receiving volume 45 in which up to a defined liquid level 47 liquid 46 in the form of water is filled. If necessary, liquid 46 can be fed into the first via a liquid inlet/liquid outlet 63, which is used bidirectionally in the example shown Piston storage element 42 can be inserted or drained from it. The level of liquid 46 in the first piston accumulator element 42 is measured via a sensor element 61 for measuring the level.

Furthermore, the storage chamber 41 has a second piston storage element 48 in the form of a reciprocating piston element, which also has a base element 49 and a side wall 50. The second piston accumulator element 48 is also cylindrical or cup-shaped. The second piston storage element 48 has a gas volume 48a, that is to say a useful volume, of less than or equal to ten liters. Both the first piston accumulator element 42 and the second piston accumulator element 48 are open at their free ends of the side walls 45, 50, which lie opposite the respective base elements 43, 49, these openings facing each other. The two piston accumulator elements 42, 48 are monolithic and are concentrically and rotationally symmetrically aligned in opposite directions, inserted into one another and axially movable relative to one another.

Between an outer surface 81 of the second piston accumulator element 48 and an inner surface 82 of the first piston accumulator element 42 there is an annularly circumferential gap 53, which is also filled with liquid 46. The ratio of the volume of liquid 46 in an internal volume 67 of the second piston accumulator element 48 and the volume 68 of liquid 46 in the gap 53 between the first and second piston accumulator elements 42, 48 is preferably greater than 5:1.

The gas to be stored is introduced into the second piston storage element 42 and stored there via a gas inlet line 54, which is guided through the base element 43 of the first piston storage element 42 into the second piston storage element 48. It is provided that the upper end 55 of the gas inlet line ends above the defined liquid level 47, and thus in an area above the liquid 46, in the second piston accumulator element 48. The upper end 55 of the gas inlet line 54 is located in the immediate vicinity of the base element 49 of the second piston storage element 48. When the storage chamber 41 is in the unexpanded state, the upper end 55 of the gas inlet line 54 is closed with a closure element 79 located on the base element 49.

In a similar manner, a gas outlet line 56 is also provided, via which the stored gas can be removed again from the storage chamber 41, in particular from the second piston storage element 48. The gas outlet line 56 is also guided through the base element 43 of the first piston accumulator element 42 into the second piston accumulator element 48. Here too it is provided that the upper end 57 of the gas outlet line 56 ends above the defined liquid level 47, and thus in an area above the liquid 46, in the second piston accumulator element 48. The upper end 57 of the gas outlet line 56 is located in the immediate vicinity of the base element 49 of the second piston accumulator element 48. In order to be able to release the gas in a controlled manner, an aperture 80 is provided on the outlet side of the gas outlet line 56. The gas pressure inside the storage chamber 41 is measured by means of a pressure sensor element 77, which is also arranged in the goose output line 56.

To ensure that the storage chamber 41 is sealed against the atmosphere so that stored gas cannot escape from the storage chamber 41 in an uncontrolled manner, the storage chamber 41 has a sealing device 58. This sealing device 58 is in turn formed by the gap 53 or by liquid 46 located in the gap 53. In a similar way, the gap 53 also takes on the function of an overpressure protection 59. This overpressure protection 59 functions as follows: For example, a quantity of purging gas flows through the gas inlet line 54, for example by opening a valve (not shown), into the second piston accumulator element 48, for approximately 300 ms . During proper operation, a "normal" deflection occurs, in particular of the second piston accumulator element 48, which is detected, for example, with a sensor element (not shown). At the end of the inflow process, the valve is closed. During normal operation, the pressure slowly reduces via the gas outlet line 56. The overpressure protection 59 is a kind of emergency solution, for example if the valve does not close or does not close properly and the second piston accumulator element 48 has reached its maximum deflection, or if the second piston accumulator element 48 tilts. In these cases, the gas pressure in the second piston storage element 48 increases. This causes the water column to be displaced downwards. The water column in the gap 53 between the first 42 and second 48 piston storage element naturally increases at the same time. Water and the gas contained therein thus “bubble” outwards via the open end 83 of the gap 53. This prevents the storage chamber 41 from bursting.

In the side wall 45, the first piston storage element 42 has a protective outlet 60 below the end 55, 57 of the gas inlet line 54 and the gas outlet line 56.

In the second exemplary embodiment shown, it is also realized that the first piston accumulator element 42 is fixed, that is to say immovable, while the second piston accumulator element 48 is movable, that is to say deflectable. For the axial mobility of the second piston accumulator element 48, the accumulator device 40 has a guide device 65, which is designed in the form of a linear guide. By means of the guide device 65, the second piston storage element 48 slides upwards, preferably linearly, when purge gas is absorbed and preferably triggers a sensor element 62 for determining the position at a defined deflection. As in the first exemplary embodiment, the second piston accumulator element 48 is guided by two plain bearings 75 on a guide rod 76. The guide rod 76 is surrounded by a hollow profile element 66 in the form of a guide tube, which represents the actual guide of the second piston accumulator element 48, and at the ends of which the sliding bearings 75 are located. The guide rod 76 runs through the hollow profile element 66, which is connected to the second piston accumulator element 48. The hollow profile element 66 slides along the guide rod 76, whereby the second piston accumulator element 48 is moved, in particular deflected. The guide rod 76 is stored/fastened in the first piston accumulator element 42. The guide device 65 is sealed at the top by a sealing element 78.

Associated with the storage device 10 is a control device 85, which is connected to other components of the storage device 10 via suitable interfaces. In Figure 10 is shown by way of example that the control device 85 is connected via an interface 84a to a valve device 84 in the gas inlet line 54, and via an interface 62a to the sensor element 62 for determining the position of the second piston accumulator element 48. Such a design can also be used in the Figures 2 to 8 illustrated embodiment can be realized.

The functionality of the storage device 40 is described below:
Initially, the storage chamber 41 is in the unexpanded state, which is in Figure 9 is shown. Via the gas inlet line 54, which is in the second piston accumulator element 48 ends, gas above the defined liquid level 47 for the liquid 46 is introduced into the second piston accumulator element 48 by opening the valve device 84.

As a result of the gas pressure that builds up, the second piston accumulator element is displaced axially against the first piston accumulator element, which in Figure 10 is shown. The second piston accumulator element 48 is deflected by means of the guide device 65, preferably up to a defined nominal height or nominal deflection, which is detected by the sensor element 62.

After the introduction of the gas has ended, the deflection stops and the gas located in the second piston accumulator element 48 is discharged via the gas outlet line 56, which ends above the liquid level 47 for the liquid 46 in the second piston accumulator element 56, preferably solely by means of the weight of the second piston accumulator element 48 the second piston accumulator element 48 is discharged. This means that the weight of the second piston storage element 48 pushes the purge gas, preferably through the aperture 80, outwards, for example into a system air flow.

Preferably, when the gas is introduced into the second piston accumulator element 48, it is directed against the base element 49 of the second piston accumulator element 48 and is deflected from there before it enters the gas outlet line 56 and is derived from there from the second piston accumulator element 48.

For example, the gas is introduced into the second piston storage element 48 for a defined period of time per storage cycle, for example for a period of less than a second, for example for 300 ms, and/or up to a defined nominal height of the second piston storage element 48. The gas is introduced over a certain period of time via a corresponding position of a valve device 84 in the gas inlet line 54. The valve device 84 is controlled by means of the control device 85 via the interface 84a. Likewise, the sensor element 62 forwards the determined values to the control device 85 via the interface 62a to determine the position of the second piston accumulator element 48. At the beginning, the valve device 84 is opened by means of the control device 85 and closed again when the time period has been reached. Alternatively or additionally, the position values of the second piston accumulator element 48 detected by the sensor device 62 are transmitted to the control device 85 and evaluated there. The control device 85 generates suitable commands that are sent to the Valve device 84 are transmitted, and due to which the valve device 84 is opened and closed again.

Reference symbol list

10

Energy system (building energy system)

11

First subsystem (internal system)

12

System cabinet

13

Second subsystem (external system)

14

Electrolysis device

15

Fuel cell device

16

Connection line device

17

Check valve device

18

Filter device

19

Dryer facility

20

Pressure measuring device

21

High pressure storage device

22

Medium pressure storage device

23

Valve device

24

Compressor device

25

Check valve device

26

Relaxation device (pressure reducer)

27

First line section

28

Second line section

29

System airflow

40

Storage device

41

Expandable storage chamber (piston storage)

42

First piston accumulator element

43

Floor element

44

side wall

45

Recording volume

46

liquid (water)

47

Fluid level

48

Second piston accumulator element

48a

Gas volume

49

Floor element

50

side wall

51

First section

52

Second section

53

gap

54

Gas inlet line

55

Upper end of the gas inlet line

56

Gas outlet line

57

Upper end of the gas outlet line

58

Sealing device

59

Overpressure protection

60

Protective spout

61

Sensor element for measuring the liquid height

62

Sensor element for determining the position of the second piston accumulator element

62a

Interface to control device

63

Liquid inlet/liquid outlet

64

Frame setup

65

Guide device (linear guide device)

66

Hollow profile element (guide tube)

67

Internal volume of liquid of the second piston storage element

68

Volume of liquid in the gap

69

Stabilizing element

70

Fastening device

71

Pin for position fixing

72

Fastening element (sheet metal angle)

73

Fastening clamp

74

Activation device for activating a sensor element to determine position

75

bearings

76

Guide rod

77

Pressure sensor element

78

Sealing element

79

Closure element

80

cover

81

Outer surface of the second piston accumulator element

82

Inner surface of the first piston accumulator element

83

Open end of the gap

84

Valve device

84a

Interface to control device

85

Control device

Claims (15)

Storage device (40) for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process, having an expandable storage chamber (41), which is designed as a piston accumulator, with a first piston storage element (42) designed as a liquid chamber, into which liquid (46) can be filled up to a defined liquid level (47) or into which liquid (46) is filled up to a defined liquid level (47), with a second piston accumulator element (48) designed as a reciprocating piston element, wherein the piston accumulator elements (42, 48), in particular concentrically, are inserted into one another in opposite directions, wherein the piston accumulator elements (42, 48) are axially movable relative to one another, and with a gas inlet line (54) and with a gas outlet line (56), characterized, in that the first piston accumulator element (42) is external in relation to the second piston accumulator element (48) and between an outer surface (81) of the second piston accumulator element (48) and an inner surface (82) of the first piston accumulator element (42) there is a, in particular circumferential, gap ( 53) is trained, and that the gas inlet line (54) and the gas outlet line (56) end (55, 57) above the defined liquid level (47) for the liquid (46) in the second piston storage element (48). Storage device according to claim 1, characterized in that the gas inlet line (54) and the gas outlet line (56) are guided anti-parallel with respect to the gas flow path, and / or that the gas inlet line (54) and the gas outlet line (56) from below through the first piston storage element (42 ) are guided into the second piston accumulator element (48). Storage device according to claim 1 or 2, characterized in that the second piston storage element (48) has a gas volume for gas to be absorbed of less than 10 liters, preferably less than 5 liters, preferably between 0.5 liters and 3 liters. Storage device according to one of claims 1 to 3, characterized in that the second piston storage element (48) has a first portion (51) which has a Bottom element (43) of the first piston storage element (42) faces, that the second piston storage element (48) has a second portion (52) which faces away from the bottom element (43) of the first piston storage element (42), that the volume of the second portion ( 52) is smaller than the volume of the first subregion (51) and/or that the cross-sectional area of the second subregion (52) is smaller than the cross-sectional area of the first subregion (51). Storage device according to one of claims 1 to 4, characterized in that the second piston storage element (48) has a base element (49) and a side wall (50) projecting from the base element (49) in the direction of the first piston storage element (42), and that in one In the unexpanded state of the storage device (40), the gas inlet line (54) and the gas outlet line (56) end (55, 57) immediately in front of the base element (49) of the second piston storage element (48), preferably in its second portion (52). Storage device according to one of claims 1 to 5, characterized in that the storage device (40) has a sealing device (58) for sealing the gap (53) against the atmosphere between the first piston storage element (42) and the second piston storage element (48), and that the sealing device (58) is/is preferably formed by liquid (46) filled into the first piston storage element (42), and/or that the storage device (40) has an overpressure protection (59) which passes through the gap (53) between the first Piston storage element (52) and the second piston storage element (48) is formed, and / or that the first piston storage element (42) is formed in a side wall (44), below the end (55, 57) of the gas inlet line (54) and the gas outlet line (56) , has a protective outlet (60). Storage device according to one of claims 1 to 6, characterized in that the volume ratio of liquid between an internal volume (67) of the second piston storage element (48) and a volume (68) of the gap (53) between the first and second piston storage elements (42, 48 ) is greater than or equal to 3:1, preferably greater than 5:1. Storage device according to one of claims 1 to 7, characterized in that the storage device (40) has at least one sensor element (77) for determining the pressure in the gas outlet line (56) or in the second piston storage element (48). and/or at least one sensor element (62) for determining the position of the second piston accumulator element (48) and/or at least one sensor element (61) for measuring the liquid level in the first piston accumulator element (42). Storage device according to one of claims 1 to 8, characterized in that the gas inlet line (54) has a valve device (84) on the inlet side, and/or that the gas outlet line (56) has a metering device or a throttle element or a diaphragm (80) on the outlet side and/or has a filter element, and / or that the first piston storage element (42) has a liquid inlet (63) and / or a liquid outlet. Storage device according to one of claims 1 to 9, characterized in that the storage device (40) for the axial mobility of the first piston storage element (42) against the second piston storage element (48) has a guide device (65), in particular a linear guide device, for the second piston storage element ( 48). Energy system (10), in particular building energy system, comprising an electrolysis device (14), a fuel cell system (15), optionally a high-pressure storage device (21), and a connecting line device (16), via which the electrolysis device (14), the fuel cell system (15) and optionally the high-pressure storage device (21) are connected to one another, characterized in that the energy system (10) has a storage device (40) according to one of claims 1 to 10 for receiving and/or temporarily storing gas, in particular purge gas discharged during a purging process. Energy system according to claim 11, characterized in that the storage device (40) is arranged in a first subsystem (11) of the energy system (10), and / or that the storage device (40) in a, in particular ventilated, system cabinet (12) of the energy system (10) is arranged. Method for receiving and/or temporarily storing gas, in particular purge gas discharged during a purge process, in an expandable storage chamber (41), which is designed as a piston accumulator, a storage device (40), wherein the storage chamber (41) is a first designed as a liquid chamber Piston storage element (42), into which liquid (46) is filled up to a defined liquid level (47), and a second piston storage element (48) designed as a reciprocating piston element, wherein the piston storage elements (42, 48), in particular concentrically, are inserted into one another in opposite directions are, wherein the piston accumulator elements (42, 48) are axially movable relative to one another, and wherein the first piston accumulator element (42) is external with respect to the second piston accumulator element (48) and between an outer surface (81) of the second piston accumulator element (48) and an inner surface (82) of the first piston accumulator element (42) a, in particular circumferential, gap (53) is formed, characterized by the following steps: a) Gas above the defined liquid level (47) for the liquid (46) is introduced into the second piston storage element (48) via a gas inlet line (54), which ends in the second piston storage element (48) (55), and the second piston storage element (48 ), preferably deflected by means of a guide device (65); b) After the introduction of the gas has ended, the gas located in the second piston storage element (48) is preferably discharged via the gas outlet line (56), which ends above the liquid level (47) for the liquid (46) in the second piston storage element (48). solely by means of the weight of the second piston accumulator element (48), discharged from the second piston accumulator element (48). Method according to claim 13, characterized in that gas is introduced into the second piston storage element (48) for a defined period of time and/or up to a defined nominal height of the second piston storage element (48). Method according to one of claims 13 or 14, characterized in that the gas, when introduced into the second piston accumulator element (48), is directed against a base element (49) of the second piston accumulator element (48) and is diverted from there before it enters the gas outlet line ( 56) occurs and is derived from there from the second piston accumulator element (48).

Images