DE102019116399A1 - Method and device for storing fluids - Google Patents

Abstract

According to the state of the art, two separate storage containers are provided for storing educts and products in chemical processes, which results in a high installation space and investment requirement and high operating costs when compressing gaseous educts and products. The device according to the invention solves this in that educt and product (2 ', 3') of a chemical reaction are stored in a common container (9), with the two substances separated from one another in two storage volumes (2, 2) with the aid of a flexible partition (8). 3) be separated. With regard to the method according to the invention, the device is used to store in particular CO2 and CH4 in a common container (9).

Description

Due to the energy transition, the requirements regarding the stabilization of the electrical network have increased, as the need to compensate for short-term differences between energy demand and energy supply has increased. In addition, the storage of energy is essential for the implementation of the energy transition.

If the demand exceeds the current supply, power plants, engines and / or turbines are usually switched on to compensate for this difference. In contrast, if more energy is produced than can currently be consumed, it would make sense to store this energy. However, electrochemical energy storage systems are too expensive, pumped storage power plants encounter resistance from the population, so that the energy is often simply destroyed.

Another possibility is to store the excess energy in the form of chemical compounds. For example, in those phases in which the electrical network has to be stabilized by taking off energy, hydrogen can be produced by electrolysis. In order to ensure better storage and use, the hydrogen can then be oxidized to methane with the help of CO ₂ and / or CO (eg Sabatier process). H ₂ + CO ₂ → CO + H ₂ O 3 H ₂ + CO -> CH ₄ + H ₂ O

The necessary CO ₂ can be obtained, for example, from the exhaust gas of power plants, turbines or motors operated with carbonaceous fuels or fuels in the phases in which these are switched on in order to stabilize the network by supplying electrical energy. The methane generated in the phases of excess energy can be used to operate power plants, turbines or engines. In the best case, this results in a cycle of generated and used or burned methane.

Since these two processes, ie the production or accumulation of CO ₂ / CO and the generation of CH _4, take place at different times, storage of both CO ₂ / CO and CH ₄ or H _{2 is} necessary. Usually this requires at least two separate stores, whereby these are always filled or emptied alternately. This leads to a large space requirement for the storage of the individual substances.

The device according to the invention solves this problem according to claim 1, the method according to the invention solves this problem according to claim 9.

The main idea is to store two different gases in a common container that is closed to the outside. There is a flexible partition between the two gases, which creates two separate storage volumes. As a result, the two gases are permanently separated from one another, but their pressure forces act on one another.

In phases in which electrical energy is required, the power plants, motors or turbines are activated to generate electrical energy, and the CO ₂ produced during the combustion of hydrocarbons such as methane is separated from the exhaust gas and directed into one of the volumes. At the same time, the previously generated CH _{4 is taken} from the other volume to operate the power plants. This reduces the CH ₄ volume, while at the same time the volume that is temporarily storing the CO ₂ / CO increases. As a result, the flexible partition is automatically deflected in the direction of the CH ₄ volume in order to compensate for the resulting pressure difference, so that more storage volume is available for CO ₂ / CO. In the phases in which there is a surplus of electrical energy, the power plants, motors or turbines are deactivated and thus the extraction from the CH ₄ volume is stopped. At the same time, CO ₂ / CO is withdrawn, generated with the help of H ₂ methane, for example in a Sabatier process, and this is then fed to the CH ₄ volume. Ie the process described above is simply reversed.

The advantage of this procedure is that only one container is required for storage, so that the space required for the storage device for the entire cycle of CO ₂ and CH ₄ generation is halved.

The method according to the invention and the device are not limited to the storage of CO ₂ and CH ₄ , but can be used in all chemical processes in which at least one starting material and at least one product must be stored.

The storage is not limited to two fluids, but according to the invention can be expanded to more than two fluids with the aid of further partition walls when further individual volumes are formed.

At least two of the stored fluids advantageously have the same physical state.

The container can be designed as a pressure vessel. Because of the very low Pressure difference between the two volumes, the partition can be made very inexpensive in contrast to the outer wall, which is a further advantage compared to the use of separate pressure vessels. A rubber tarpaulin is ideal for this.

• - EPDM
• - EPDM- Kautschuk
• - Kautschuk
• - PTFE
• - Fluorkautschuk (FKM) (z.B. Viton)
• - Perfluorkautschuk FFKM
• - Vinyliden(di)fluorid haltige Kautschuke (VDF)
• - PVC
• - Polyester
• - Polypropylen
• - Polyethylen
• - Polyamid
• - Polyurethan

Possible other materials are

• - EPDM
• - EPDM rubber
• - rubber
• - PTFE
• - Fluororubber (FKM) (e.g. Viton)
• - Perfluorinated rubber FFKM
• - Rubber containing vinylidene (di) fluoride (VDF)
• - PVC
• - polyester
• - polypropylene
• - polyethylene
• - polyamide
• - polyurethane

All material variants can also be stabilized by means of fabric; the fabric and the sealing material are advantageously inseparable.

In addition, the above-mentioned materials can be combined with one another or with other materials, for example by arranging several films, in particular different materials, one on top of the other. A combination with other materials provides e.g. the combination of polyurethane with silanes.

Another possibility is to provide the plastic-containing wall with a metallic layer in order to minimize the diffusion of the gases through the partition. This is state of the art and can be implemented by electroplating, sputtering, vapor deposition, chemical vapor deposition, etc.

It is also possible to arrange a thin separate metal layer, in particular in the form of a metallic foil.

The elongation at break of the partition is at least 150%, advantageously at least 200%, extremely advantageously at least 300%.

The wall thickness of the partition is at least 0.5 mm, advantageously at least 1 mm, extremely advantageously at least 1.5 mm.

The density of the partition is at least 0.7 kg / dm3, advantageously at least 0.9 kg / dm3, extremely advantageously at least 1.1 kg / dm3.

The gas permeability of the partition wall at 23 ° C is a maximum of 300cm ³ / (m ² * bar * d), advantageously a maximum of 250cm ³ / (m ² * bar * d), extremely advantageously a maximum of 200cm ³ / (m ² * bar * d) , with “d” as the thickness of the wall in mm.

The tear strength with a thickness of 1.5 mm for a 5 cm test strip is at least 400N, advantageously at least 500N, extremely advantageously at least 600N.

The breaking strength at a thickness of 1.5 mm is at least 80N, advantageously at least 120N, extremely advantageously at least 150N.

In order to prevent the partition from being exposed to too high a pressure difference (e.g. whenever one of the volumes is completely emptied), the differential pressure between the two volumes and / or the position of the partition is monitored. If this exceeds a predetermined limit value, either the withdrawal or the supply is stopped and / or on the side with the higher pressure, the gas is released.

In order to prevent the partition wall from adhering to the container wall in the end positions, devices are attached between the container wall and the partition wall in order to avoid a smooth surface. This can e.g. can be achieved by knobs, ridges and grooves. When using grooves, it is advantageous to design these in such a way that they are in fluid communication with the container opening.

In order to prevent the partition wall from being pulled into the container outlet and thereby damaged, it can be reinforced in this area. The wall thickness of the wall in this area should be at least 2mm, advantageously at least 3mm, extremely advantageously at least 5mm.

Another possibility is to use a solid plate in this area of the partition, e.g. made of metal, which is larger than the container outlet. When empty, this rests on the container wall and prevents mechanical stress on the rubber wall.

Another possibility is to attach a perforated intermediate plate at least in the container outlet, on which the intermediate wall can be supported when it is empty.

Both the method and the device can be used in vehicles, in particular in Passenger cars, trucks and ships as well as construction and work machines are used.

• 1: Erfindungsgemäße Vorrichtung mit gleichmäßiger Befüllung mit zwei Gasen
• 2: Einbindung der erfindungsgemäßen Vorrichtung in das erfindungsgemäße Verfahren aus Speicherung von Energie und Speicherung von Verbrennungsprodukten
• 3a: Erfindungsgemäße Vorrichtung mit hauptsächlicher Befüllung mit dem Gas 2
• 3b: Erfindungsgemäße Vorrichtung mit hauptsächlicher Befüllung mit dem Gas 3
• 4: Schnitt durch die Behälterwand der erfindungsgemäßen Vorrichtung mit gelochter Zwischenplatte (10) im Auslassbereich (5)
• 5: Schnitt durch die Behälterwand der erfindungsgemäßen Vorrichtung mit Abstandsnoppen (21) auf der Behälterinnenwand
• 6: Schnitt durch die Behälterwand der erfindungsgemäßen Vorrichtung mit Rillen (22) auf der Behälterinnenwand
• 7: Draufsicht auf die Behälterinnenwand im Bereich des Behälteraus- und Behältereintritts (4,5) mit Rillen (22), die in fluidtechnischer Verbindung mit dem Behälteraus- und Behältereintritt (4,5) stehen

In the following, the device according to the invention and the method according to the invention will be explained with reference to figures.

• 1 : Device according to the invention with uniform filling with two gases
• 2 : Integration of the device according to the invention in the method according to the invention comprising storage of energy and storage of combustion products
• 3a : Device according to the invention with mainly filling with the gas 2
• 3b : Device according to the invention with main filling with the gas 3
• 4th : Section through the container wall of the device according to the invention with a perforated intermediate plate ( 10 ) in the outlet area ( 5 )
• 5 : Section through the container wall of the device according to the invention with spacer knobs ( 21st ) on the inside wall of the container
• 6th : Section through the container wall of the device according to the invention with grooves ( 22nd ) on the inside wall of the container
• 7th : Top view of the inner wall of the container in the area of the container outlet and container inlet ( 4th , 5) with grooves ( 22nd ), which are in fluid communication with the tank outlet and tank inlet ( 4th , 5) stand

1 shows the device according to the invention ( 1 ): With the help of a container outer wall ( 9 ) the gases ( 2 ' , 3 ') and prevented from escaping into the environment. The container ( 9 ) can be designed as a pressure vessel. In this case it is advantageously made spherical or cylindrical in order to be able to better compensate the pressure forces. Between the two gases ( 2 ' ) and (3 ') there is a flexible partition ( 8th ), which separates the two gases from each other. The two areas or partial volumes ( 2 , 3 ) can be filled or emptied with gas via at least one inlet or outlet (5, 4). According to the invention, emptying and filling take place alternately, ie the gas space ( 3 ) is filled, the gas compartment ( 2 ) emptied. This is shown by the direction of flow at the current outlet ( 5 ) and current admission ( 4th ). If, on the other hand, the gas space ( 2 ) are filled, the gas compartment ( 3 ) so that the previous inlet becomes the outlet and the previous outlet becomes the inlet (cf. 3b) . Via the valves ( 6th , 7) the inlets and outlets, i.e. the inlets and outlets ( 4th , 5 ) are locked or opened.

2 shows the device according to the invention embedded in the method according to the invention using the example of a CO ₂ / CH ₄ cycle. In the gas area ( 2 ) is methane ( 2 ' ) contain that in the mode shown 1 over the outlet 5 and the open valve ( 15th ) an internal combustion engine, especially a turbine or a motor ( 11 ) is supplied. The internal combustion engine is also supplied with air ( 32 ) supplied. The combustion of methane in the turbine or engine ( 11 ) resulting CO ₂ (3 ') is then in a corresponding device ( 12 ) from the remaining exhaust gas ( 19th ) separated and the container space ( 3 ) via the open valve ( 17th ) supplied. The separation of CO ₂ from exhaust gas is state of the art and can take place, for example, by pressure swing adsorption, gas scrubbing, membrane processes, so that this will not be discussed further. The internal combustion engine is connected to a generator (not shown), via which electrical energy is made available to consumers. It is also possible to make mechanical energy available. If the methane stored in the container is insufficient, the internal combustion engine can also be supplied with external fuel, in particular methane. In the described mode of the activated internal combustion engine, the valves ( 16 , 18th ) closed. CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O Equation I.

In mode 2 (not shown) the internal combustion engine ( 11 ) deactivated, the valves ( 15th , 17th ) closed and the valves ( 16 , 18th ) open. From the now filled container area ( 3 ) CO ₂ flows to the methanizer ( 13th ). With the help of supplied H ₂ ( 30th ), which can be produced electrolytically (not shown), methane and water are formed. CO ₂ + 4H ₂ → CH ₄ + 2H ₂ O Equation II

This can e.g. after the Sabatier process.

In the next step ( 14th ) the resulting water ( 31 ) separated in a separator and discharged. The methane is then fed into the tank space via the open valve ( 2 ), whereby this increases and the container space ( 3 ) reduced.

The device according to the invention thus stores within a total volume in a first partial volume ( 2 ) at least one educt ( 2 ' ) a reaction and in a second partial volume ( 3 ) at least one product ( 3 ' ) of this reaction whereby the partial storage volumes are separated by a partition ( 8th ) are separated from each other and increase or decrease in opposite directions. Due to the reversibility of the discharge and filling processes, the product of one reaction (e.g. CO ₂ from the combustion of Methane) to the educt of a second reaction (e.g. Sabatier process for the production of methane from CO ₂ ) and vice versa.

For the sake of clarity, conveying devices for the educts and products, such as pumps or fans, are not shown.

In order to be able to better utilize the storage volume, the containers ( 9 ) supplied gases compressed with the help of compressors (not shown here). In processes that take place at increased pressure or require the feed of the starting materials at increased pressure, this represents a further advantage of the method according to the invention: Since the pressures in the two partial volumes interact via the partition wall and are therefore almost identical, the compressors must only the change in volume during the reaction and the pressure losses in the chemical systems and piping are compensated. In the event that the amount of reactant converted and the amount of product formed are identical, there is no change in volume and only the pressure losses of the system and the piping must be expended by the compressors. An example is the above-described coupling of the combustion of methane to CO ₂ according to equation I and the formation of methane from CO ₂ according to equation II. In both cases there is a 1: 1 conversion of methane and CO ₂ , so that Total volume of CO ₂ and CH ₄ remains constant.

The method according to the invention is not limited to the storage of CO ₂ and CH ₄ , but can be used in all chemical processes in which at least one starting material and at least one product must be stored.

The storage is also not limited to two fluids, but can be expanded according to the invention to more than two fluids with the formation of further individual volumes with the aid of further partition walls.

At least two of the stored fluids advantageously have the same physical state.

For example, in the process described above with the aid of CO ₂ and CH ₄ , at least part of the water formed during the combustion of CH ₄ and / or the methanation of CO ₂ ( 19th , 31 ) in a third volume within the container ( 9 ) save.

This is also useful when coupling the electrolysis of water with a fuel cell (not shown here). As already described above for the process with CO ₂ and CH ₄ , in a first mode the hydrogen and oxygen stored separately in two partial volumes are converted into electrical current with the aid of a fuel cell. The water formed is in a third volume inside the container ( 9 ) saved. In a second mode, the water formed in the first mode is taken from the third partial volume and hydrogen and oxygen are formed via electrolysis, which are fed to the other two partial volumes separately from one another. As already described for CO ₂ and CH ₄ , a cycle can be built up through which electrical energy can be emitted and absorbed, i.e. stored.

In the 3a and 3b are different degrees of filling of the two container spaces and thus different deflections of the partition wall ( 8th ) shown. While in 3a the entire device mainly with the substance ( 3 ' ) is filled, takes in 3b the fabric ( 2 ' ) the main volume within the total container ( 9 ) a. In addition, the 3a a filling process with the gas ( 3 ' ) and an emptying process for the gas ( 2 ' ) while 3b shows the reverse process.

4th shows the section through the container ( 9 ) in the outlet area. The container is completely from the gas ( 2 ' ) via the outlet ( 5 ) emptied so that the partition wall ( 8th ) on the container ( 9 ) is present. To prevent the partition wall from entering the outlet ( 5 ) is pulled and damaged, a perforated or slotted intermediate plate ( 10 ) provided on which the partition wall ( 8th ) can support. The formation of a gap between the intermediate plate ( 10 ) and container ( 9 ) is possible (not shown).

In order to avoid the partition wall ( 8th ) when a partial volume is completely emptied on the container wall ( 9 ), nubs and / or webs ( 21st ) provided that a distance between the partition wall ( 8th ) and container wall ( 9 ) train. This is shown in 5 , which shows a section through the container wall. This creates a minimal residual volume, e.g. in the form of grooves ( 22nd ), ensured that the partition wall ( 8th ) prevented. The knobs and / or bars can be made of a different material than the container ( 9 ) are manufactured. For reasons of cost, plastics can be used here.

The same effect is achieved if the container wall ( 9 ) and knobs, ribs ( 23 ) are made of the same material ( 6th ). In terms of production technology, this can be represented by welding or gluing. In addition, the grooves can be made by milling the container wall ( 9 ) produce.

Both in the 5 and 6th described devices are used when using grooves and ribs ( 22nd ) advantageously designed so that it is fluidically connected to the container opening ( 4th , 5 ) stay in contact. In addition, the invention provides that these ribs and grooves with one another via cross connections ( 22a) are in fluid communication. This is shown in 7th covering the interior of the container ( 9 ) shows in plan view.

The description aims at a separate storage of CO ₂ and CH ₄ in the two partial volumes ( 2 ) and (3), but, as already described above, is not limited to these. In particular, separate storage of N ₂ and NH ₃ , H ₂ and NH ₃ , H ₂ and CH _4, H ₂ and HCHOH, CO ₂ and dimethyl ether (DME), CO ₂ and diethyl ether (DEE), CO _{2 is also possible} and polyoxymethylene dimethyl ether (POMDEM), H ₂ and alcohols, H ₂ and O ₂ , CO ₂ and alcohols, CO ₂ and higher hydrocarbons with a number of carbon atoms C> 3 in the partial volumes. The device according to the invention is not limited to the storage of CO ₂ and CH ₄ and the compounds described above, but can be used in all chemical processes in which at least one starting material and at least one product must be stored.

From this list it becomes clear that according to the invention not only gases are stored in the device and the method, but also liquids. Liquids can be stored due to their higher energy and storage densities compared to gases. For example, CO ₂ can be liquefied by increasing the pressure. Since this does not work for methane, the representation of dimethyl ether (DME) or longer-chain hydrocarbons such as butane, heptane or alcohols is recommended instead of methane. These can then be liquefied, analogously to CO ₂ , or are already in liquid form at ambient pressure.

In addition to hydrocarbons, ammonia is another storage medium, as it can also be easily liquefied.

The storage is not limited to two fluids, but according to the invention can be expanded to more than two fluids with the aid of further partition walls when further individual volumes are formed (not shown here).

It is advantageously provided that at least two of the stored fluids have the same physical state.

Due to the weight of the partition wall ( 8th ) if the partition wall is not arranged vertically ( 8th ) a greater pressure in the lower partial volume than in the upper partial volume. Should in both partial volumes ( 2 , 3) the same pressure prevails, the partition wall is not horizontal, but particularly advantageously vertical within the container ( 9 ) arranged.

If there is a greater pressure difference between the two partial volumes ( 2 , 3 ) desired, an additional force is applied to the partition wall in the direction of the higher volume. In the simplest case, this can be achieved by a non-vertical arrangement of the partition wall ( 9 ) and applying additional weights and / or using a thick partition. The thickness of the partition is greater than the thickness that would be necessary in terms of sealing or mechanical strength.

The operation of internal combustion engines with DME, DEE, POMDME, alcohols, higher hydrocarbons and NH ₃ is state of the art, so this will not be discussed further.

Claims (10)

Device for storing at least two different fluids (2 ', 3') in a common container (9), characterized in that with the help of at least one flexible partition (8) at least two separate storage volumes (2, 3) for the separate storage of the at least two Fluids (2 ', 3') are formed within the container (9) and these two storage areas can be filled and emptied via feed and discharge devices (4, 5). Device according to Claim 1 , characterized in that the partition (8) contains at least one of these substances: a. Rubber b. EPDM c. EPDM rubber d. Rubber e. PTFE f. Fluororubber (FKM) g. Perfluorinated rubber (FFKM) h. Vinylidene (di) fluoride containing rubbers (VDF) i. PVC j. Polyester k. Polyethylene I. Polyamide m. Polypropylene n. Polyurethane Device according to one of the preceding claims, characterized in that the elongation at break of the partition is at least 150%, advantageously at least 200%, extremely advantageously at least 300%. Device according to one of the preceding claims, characterized in that the gas permeability of the partition wall at 23 ° C is a maximum of 300 cm ³ / (m ² * bar * d), advantageously a maximum of 250 cm ³ / (m ² * bar * d), extremely advantageously a maximum of 200 cm ³ / (m ² * bar * d), where “d” represents the wall thickness in millimeters. Device according to one of the preceding claims, characterized in that the intermediate wall (8) consists of several layers and the materials of the layers differ from one another. Device according to Claim 5 , characterized in that at least one additional layer is a metallic layer, in particular a metallic foil. Device according to one of the preceding claims, characterized in that devices (21, 22) for spacing the partition wall (8) from the container wall (9), in particular knobs, grooves or webs, are applied or formed on the inside of the container (9) . Device according to Claim 7 , characterized in that the grooves (22) formed are in fluid communication with one another and / or with the feed and discharge devices (4, 5). A method for storing at least two different fluids (2 'and 3') from or for a common chemical process in which one fluid is used as an educt and the other fluid is created as a product, characterized in that the at least two fluids (2 'and 3') are stored in a common container (9), in which at least two separate storage volumes (2, 3) for the separate storage of the fluids (2 ') and (3 ') are formed and the two volumes are each filled or emptied in opposite directions. Procedure according to Claim 9 , characterized in that at least one second chemical process is coupled to the individual volumes (2, 3) and the product from the first chemical process is used as an educt for the second process and vice versa, the two processes running consecutively and via suitable shut-off devices (15, 16, 17, 18) the fluids are fed to the individual chemical processes and sub-volumes when these chemical processes are active.

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