METHODS, SYSTEMS AND INSTALLATIONS FOR THE COMPRESSION, EXPANSION AND/OR STORAGE OF A GAS
This method is used to manage a pressure accumulator (1) as a component of an energy storage system, consisting of a work machine (4), a collecting tank (7), a displacement apparatus (6) and a pressure accumulator (1) for storing a pressurised gaseous medium. The pressure accumulator (1) is partially filled with a liquid medium so as to be able to control the gas storage volume therewith. Feeding compressed gas (3) into the pressure accumulator (1) involves removing liquid (2). Removing compressed gas (3) from the pressure accumulator (1) involves feeding in liquid (2) so that the storage pressure is kept under control as necessary, in particular is kept constant. To this end, one pressurised unit of gas (3) is introduced into the pressure accumulator (1) with the removal of one unit of liquid (2) from the pressure accumulator (1) by means of the displacement apparatus (6) and vice versa. The present method and the present arrangement make it possible to fill the pressure accumulator (1) completely with and to empty the pressured storage unit (1) completely of pressurised gas (3) at a controllable pressure, which leads to improved utilisation of the pressure accumulator volume and thus increases the energy density of the energy storage system. The method further makes it possible to operate the energy storage system at a constant operating point, thus increasing the efficiency of the individual components and of the entire system, and minimising the compression and expansion processes in the pressure accumulator (1).
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This application is a national stage entry of PCT/EP2019/062592 filed May 16, 2019, which claims priority benefit to CH 00609/18 filed May 16, 2018, each of which is expressly incorporated herein in its entirety.
This method is used to manage a pressure storage tank as a component of an energy storage system, consisting of a working machine, a collecting basin for receiving liquid, a shifting device and a pressure reservoir for storing a pressurized gaseous medium. The pressure reservoir is filled to a certain extent with a liquid medium in order to be able to control the gas storage volume, whereby the charging of the pressure reservoir with pressurized gas is accompanied by the withdrawal of liquid. The withdrawal of pressurized gas from the pressure storage tank is accompanied by the charging of liquid, in particular so that the pressure storage tank pressure is kept constant by introducing a pressurized unit of gas with the unit of liquid withdrawn from the pressure storage tank into the pressure storage tank by means of the shifting device. Conversely, a unit of gas to be removed from the pressure storage tank is conveyed out of the pressure storage tank by the unit of liquid introduced into the pressure storage tank by means of the shifting device. This method or arrangement makes it possible to fill and empty the pressure storage tank completely with pressurized gas, which leads to a better utilization of the pressure storage volume and thus increases the energy density of the energy storage system. In addition, the pressure fluctuations in the pressure storage tank are minimized, which reduces the loads on the pressure storage tank and minimizes the heat flows into and out of the pressure storage tank. The working machine can be optimized for one operating point, independent of the filling level of the pressure storage tank, which brings further advantages.
Energy storage systems, such as a battery or a pumped storage power station, are used to store energy that is made available again in times of high energy demand. Energy storage is established in conventional energy production and is increasingly required for the generation of renewable, electric power in order to prevent overcapacities in the generation and distribution of electricity. Since, for example, the solar and wind energy generated depends on local weather conditions and can therefore be adjusted poorly or not at all to the current energy demand, possibilities for energy storage are in demand.
Storage systems that store energy in the form of a pressurized gas use energy generated during off-peak periods to compress a gaseous medium, primarily ambient air, and store the pressurized gas in a pressure storage tank. The energy stored in the pressure storage tank can be recovered by using the pressurized gas to drive an expansion machine, which for example drives a generator. This concept is known in various forms as CAES, an abbreviation for Compressed Air Energy Storage. In the following description of the invention, the term “air” may be used, although a wide variety of gaseous media can of course be used in accordance with the invention, such as natural gas taken from the pipeline network and stored under higher pressure in a pressure storage tank, which is later expanded to the pressure of the pipeline network. In general, gas withdrawn from a first reservoir is compressed by increasing the pressure and stored in a second reservoir which has an increased pressure level compared to the first reservoir, and/or gas withdrawn from the second reservoir is expanded and fed to a third reservoir which is at a lower pressure level than the second reservoir, this “third reservoir” may also be the first reservoir.
During the compression of air, almost all of the compression energy used is converted into heat, which is removed from the compressed air either during compression or afterwards in order to store the compressed air at moderate temperatures. If the heat dissipation occurs mainly during compression, the compressed air heats up less than if the heat is dissipated from the air only after compression. Depending on the maximum temperature difference of the air (difference between the temperature of the air at the beginning of compression and the maximum temperature during compression), it is spoken of isothermal compression (heat is largely dissipated during compression and the temperature difference remains minimal), polytropic compression (heat is partially dissipated during compression and the temperature difference lies between the minimum and maximum difference) or adiabatic compression (heat is largely dissipated after compression, resulting in a maximum temperature difference). The same applies to the expansion of compressed air, except that here the heat flow is reversed. If heat is added to the compressed air during the expansion, the air cools down less than if heat is only added to the air before or after the expansion, whereby the air experiences a maximum temperature difference. A difference in the design of the different CAES concepts occurs in where and at what temperature difference the heat flows are dissipated before, during and/or after compression, where the heat for the expansion of the compressed air comes from, and at what temperature difference the heat is supplied to the air before, during and/or after expansion of the air.
Besides the type of compression and expansion (isothermal, polytropic, adiabatic/single or multi-stage/with reversible working machine or with a compressor and expansion machine separately, under combustion of fuels), CAES concepts differ in the type of the pressure storage concept used. Here, a distinction is made as to whether a constant or variable pressure storage volume is used. If a constant pressure storage volume is charged or discharged with compressed air, the pressure of the compressed air in the pressure storage changes linearly with the stored amount of compressed air. This requires a working machine that can adapt to the storage pressure and usually prevents the complete emptying of the pressure storage tank, since the working machine can only work in a certain pressure range. As a result, a certain amount of compressed air must always remain in the pressure storage tank in order not to fall below the minimum working pressure of the working machine. Depending on the pressure storage tank, the pressure may only fluctuate within a certain range in order not to overload the pressure storage tank, which also makes it impossible to completely empty the pressure storage tank. The thermal heat flows into and out of the pressure storage tank are also not negligible, since the compressed air in the pressure storage tank is also compressed or expanded during filling and emptying.
When loading or unloading a pressure storage tank with variable storage tank volume, the pressure change of the compressed air in the pressure storage tank can be controlled. This is usually done with the aim of keeping the pressure of the air in the pressure storage tank constant or at least within a certain range during filling or discharging of the pressure storage tank. A constant storage pressure makes it possible to fill and empty the pressure storage tank completely with compressed air without having to adjust the operating parameters of the working machine to the filling level. In addition, the pressure storage tank experiences no or only minimal pressure fluctuations, which reduces the load on the pressure storage tank. Heat flows into and out of the pressure storage tank are also minimized.
During the realization of the different concepts different technical problems arise, which are shown in the following. DE19803002892/U.S. Pat. No. 4,392,354, for example, reveal an arrangement of a partially water-filled pressure storage tank in which the pressure of the compressed air in the pressure storage tank is kept constant by a water column. In order to absorb the displaced water when the pressure storage tank is loaded with compressed air, a collecting basin must be located at the upper end of the water column. At a storage pressure of 60 bar, for example, the water column must be 600 m high, which leads to a geographical dependency for the pressure storage tank.
US20120174569 A1/U.S. Pat. No. 9,109,512 B2 show an arrangement with a higher collecting basin and a hydraulically driven 2-stage piston compressor/expander. When emptying the pressure storage tank, the hydrostatic pressure of the water column maintains the minimum pressure in the pressure storage tank. To bring the pressure storage tank to a higher pressure level than the difference in height between the pressure storage tank and the collecting basin allows, only the collecting basin has to be isolated from the pressure storage tank. As soon as the pressure in the pressure storage tank corresponds to the hydrostatic pressure of the water column when the pressure storage tank is discharged, the collecting basin is reconnected to the pressure storage tank and keeps the pressure above the minimum storage pressure when the pressure storage tank is further emptied. Here, too, there is a geographical dependency for a higher-lying collecting basin.
US20120305411A1/U.S. Pat. No. 8,801,332B2 shows a construction of a pressure storage tank, which is installed under water. At the lower end of the pressure storage tank there is an opening through which the water is pressed into the pressure storage tank by the hydrostatic pressure. Compressed air is led into or out of the tank by a working machine located above the water level. There are further versions of underwater (constant) pressure storage tanks, for example in the form of an air-filled balloon which is kept under water. All these configurations depend on the geography and the pressure tank experiences a buoyancy force due to the stored compressed air, which has to be compensated to keep the pressure storage tank under water.
Furthermore, a system is known from the state of the art according to WO1993006367A1 in which two washed out salt caverns are partly filled with liquid and have a fluidic connection on the liquid and gas side. Such salt stocks for the leaching of salt caverns only exist in very few selected geographical areas. The system can only be set up and operated in such regions and is therefore very limited in its implementation. When filling the deeper-lying cavern with compressed air, the pressure fluctuation in the cavern is reduced by the simultaneous removal of liquid. The system is dependent on a higher-lying collecting basin and the two caverns must be located at different depths, which corresponds to a geographical dependency. If the existing height difference is too small, i.e. the hydrostatic pressure is lower than the pressure in the lower-lying cavern, the pressure in the cavern is regulated with a liquid motor or a liquid pump. This fluid motor or fluid pump reduces the overall efficiency and the power input or output of the system. The system according to WO1993006367A1, and in particular the design example according to
In order to eliminate the geographical dependency or the required altitude difference, the pressure in the pressure storage tank can be controlled with a liquid, as shown in WO2012160311A2, by charging the pressure storage tank with compressed air and expanding the liquid from the pressure storage tank by means of a liquid motor into a collecting basin, which does not have to have an altitude difference. Conversely, when taking compressed air out of the pressure storage tank, liquid is pumped from the collecting basin into the pressure storage tank to control the pressure in the pressure storage tank. This has the disadvantage that the overall efficiency and the total power consumption of the system (in relation to the installed air compressor/expander power and liquid motor/pump power) becomes smaller, because when compressing air and filling the pressure storage tank, liquid must be expanded from the pressure reservoir at the same time and vice versa when expanding air, liquid must be pumped into the pressure storage tank at the same time.
The teachings of WO2008023901 A1/US20090200805 A1/U.S. Pat. No. 7,663,255 B2 eliminate the geographical dependency and the problem of power and efficiency reduction by an additional liquid pump/motor, because in addition to the first pressure storage tank, which is partially filled with a liquid and connected to the air compressor/expander, a second pressure storage tank must be available, which again must be partially filled with a liquid. This second pressure storage tank is hermetically sealed on the gas side and connected to the first pressure storage tank via a line, so that when the first pressure storage tank is loaded with compressed air, a liquid pump built into the line pumps liquid from the first to the second pressure storage tank, where it compresses the enclosed gas. When the first pressure tank is empty, i.e. filled with liquid, the gas trapped in the second pressure storage tank is at the minimum system pressure. When the first pressure storage tank is filled with compressed air and the liquid has been pumped into the second pressure storage tank, the pressure in the second pressure tank is several times higher than in the first pressure tank. The second pressure storage tank can store little energy in relation to the maximum operating pressure and its volume, which makes the system expensive.
Accordingly, the task of the present invention is to create a structurally simple, inexpensive and reliable pressure storage system which is capable of controlling the pressure of the compressed air in the pressure storage tank during the loading or unloading of the pressure storage tank with compressed air with a liquid,
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- firstly, without having to rely on the hydrostatic pressure of a column of liquid (higher level collecting basin or underwater storage tank), that means no height difference between two containers is necessary,
- and secondly, no hermetically sealed gas cushion in one or more pressure storage tanks and/or containers is necessary,
- and thirdly, without the disadvantage of the above-mentioned reduction in power and efficiency, that means that for the shifting of liquid only the overcoming of a pressure difference caused by friction and flow losses as well as a pressure difference caused by a possibly existing height difference is necessary,
and with the advantage of a high energy density in the system, and with good control over the heat flows into and out of the system, which complements the actual pressurized storage system with an efficient and flexible heat or cold generation.
This task is solved by a pressurized storage system according to the characteristics of patent claim 1 for a process and according to the characteristics of patent claim 8 for an installation for carrying out the process.
The property of controlling the pressure in the pressure storage tank during filling with compressed gas or withdrawal of compressed gas with a liquid, in particular to keep it constant,
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- firstly, without having to rely on the hydrostatic pressure of a column of liquid (higher level collecting basin or underwater storage tank), that means no height difference between two containers is necessary,
- and secondly, no hermetically sealed gas cushion in one or more pressure storage tanks and/or containers is necessary,
- and thirdly, without the disadvantage of the above-mentioned reduction in power and efficiency, that means that for the shifting of liquid only the overcoming of a pressure difference caused by friction and flow losses as well as a pressure difference caused by a possibly existing height difference is necessary,
we designate in the following also as when required low-power filling of the pressure storage with compressed gas or when required low-power withdrawal of compressed gas from the pressure storage, or in general when required low-power displacement of compressed gas into or out of the pressure storage. The system does not depend on any height difference, but can, for example, work with a height difference between two containers of 10 meters, which may be due to a requirement for a specific installation site. With this height difference of 10 meters, a hydrostatic pressure of 1 bar can be built up from a water-liquid column, which is technically not usable for energy storage due to the low energy density. The maximum energy density that can be achieved by this hydrostatic pressure of 1 bar is given when the collecting basin or the lower pressure level is at 1 bar ambient pressure and the storage pressure can be doubled with the hydrostatic pressure from 1 bar to 2 bar. Then the following energy density results:
This low energy density is not technically usable to store energy. Technically useful energy densities for energy storage start at around 1 kWh/m3. Systems that achieve a reasonable energy density in this order of magnitude with hydrostatic pressure are dependent on significant height differences above 100 meters. Therefore, these existing processes, systems and the equipment necessary for the implementation of compression, expansion and/or storage of a gas can be clearly distinguished from such known systems. Furthermore, the displacement or shifting of compressed gas into or out of the pressure reservoir for the displacement or shifting of liquid only involves a pressure difference for overcoming friction and flow losses as well as a pressure difference caused by any existing altitude difference. The resulting combined pressure difference is made up of the friction and flow losses plus the hydrostatic pressure of a water-liquid column, which is 1 bar for example at a height difference of 10 meters. At this pressure difference, the reduction in performance and efficiency is further negligible and the method of the present invention can be applied analogously.
The fact that the charging of the pressure storage tank with compressed air is accompanied by the withdrawal of liquid from the pressure storage tank and that the withdrawn liquid is used to move the compressed air into the pressure storage tank at the same time means that the pressure in the pressure storage tank can be controlled, and in particular kept constant. The compressed air can also be introduced into the pressure storage tank without further compressing the compressed air in the pressure storage tank. The quantity of liquid removed from the pressure storage tank is moved to the collecting basin after the shifting process for introducing compressed air into the pressure storage tank, in order to be shifted back into the pressure storage tank when compressed air is removed from the pressure storage tank.
In order to fill or empty the pressure storage tank with working machines (compressor/turbine) of any design, a shifting device is required in addition to the pressure storage tank and the collecting basin. This shifting device can additionally be used as a compression stage or as a pressure expansion stage. The shifting device can also be arranged parallel and/or serially. Since the shifting device can also be used as compressor/expansion stage, an additional working machine (compressor/turbine) is not necessarily required, or at least one compressor/expansion stage in the working machine can be replaced by the shifting device.
The liquid in the system can be used as a heat buffer if required to store compression heat and reuse this heat later during expansion to prevent the system from overcooling. It is also possible to use the compression heat in other ways (e.g. in buildings for hot water and heating) and to return the heat for expansion to the system from the environment, or vice versa, the compression heat can be released to the environment and heat for expansion can be returned to the system from other sources (e.g. for cooling buildings). Of course, the compression heat can be used elsewhere and the heat for expansion can be drawn from an object to be cooled. This makes sense because the compression heat can be released at a different temperature level than the temperature level at which the heat for expansion is fed back into the system.
A constant pressure in the pressure storage tank means that the compression or expansion processes in the pressure storage tank itself are eliminated, so that the heat flows into and out of the pressure storage tank are also eliminated and all compression heat and/or expansion cold can be dissipated at the compressor or expander. This results in a pressure storage system combined with efficient heat or cold generation by minimizing the heat flows into and out of the pressure storage tank. A so-called system with trigeneration, a combined heat-power-cold coupling enables the sectorial coupling of electricity, heat and cold production.
In order to eliminate the given dependencies between heat generation and filling of the pressurized storage tank as well as cold generation and emptying of the pressure storage tank and to achieve full flexibility with regard to the satisfaction of demand for electricity, heat and cold, the pressurized storage system must contain at least two compressor/expansion stages arranged in parallel. This allows heat or cold to be generated independently of the level of the pressure storage tank by simultaneously compressing air and expanding air.
Preferably, the shifting container is partially filled with a solid mass which serves as regenerator mass. For example, metal or ceramics, preferably with a large surface area compared to the volume, can be used to dissipate heat into or out of the air, which is then absorbed or released consecutively by the liquid or by a heat exchanger.
It is understood that the liquid can be in direct contact with the air or can be separated from the air by various media separation devices such as bubbles, pistons, membranes, etc. The fluid can either be displaced directly by a fluid pump/motor or by pistons, which are displaced for example by a hydraulic or pneumatic piston or by a crankshaft with connecting rod.
The invention is described below using the figures and its function is explained. It shows:
The shifting device 6 is characterized by the fact that on the gas side a fluidic connection 11, 12 can be established to the working machine 4 and/or the pressure storage tank 1 and that on the liquid side a fluidic connection 13, 14 can be established to the pressure storage tank 1 and/or the collecting basin 7, namely in such a way that it is possible to transport liquid into or out of the pressure reservoir 1 or the collecting basin 7 and in the same time to shift, compress or expand gas which is in the shifting device 6 or the pressure storage tank 1.
By moving liquid from the pressure storage tank 1 or the collecting basin 7 into the shifting device 6, the gas in the shifting device 6 can be shifted into the pressure storage tank 1 or into the working machine 4 and/or the gas can be compressed by means of the shifting device 6, depending on whether the gas in the shifting device 6 is connected with a fluidic connection 11, 12 to the working machine 4 or to the pressure storage tank 1 or whether the connections 11, 12 are interrupted. The flow directions of the flows generated by the shifting device 6 and/or by the working machine 4 through the fluidic connections 10, 11, 12, 13, 14 are shown with arrows.
By shifting liquid from the shifting device 6 into the pressure storage tank 1 or into the collecting basin 7, gas from the pressure storage tank 1 or from the working machine 4 can be sucked into the shifting device 6 or can move up and/or the gas in the shifting device 6 can be expanded by the shifting device 6, depending on whether there is a fluidic connection 11, 12 to the working machine 4 or to the pressure storage tank 1 for the gas in the shifting container or whether the connections 11, 12 are interrupted.
In the case of an existing fluidic connection 11 of the shifting device 6 to the working machine 4, there may also be a connection to the gas source/sink 5 or to gas at a pressure level between that of the pressure storage tank 1 and that of the gas source/sink 5 or to gas at or above the pressure level of the pressure storage tank 1 or generally to gas at any pressure level.
The arrangement of
The arrangement of
At this point it should also be mentioned that the shifting mechanism 61 must of course also be driven or braked, and that this can be done in various ways, for example by a mechanical connection to the working machine and its drive and output, or by a separate drive or output respectively. This mechanical connection or this input and output are not shown in
The various operating modes resulting from the arrangement of
The process shown in
Then the fluidic connection 11 between the working machine 4 and the shifting container 60 is interrupted and the fluidic connection 12 between the shifting container 60 and the pressure storage tank 1 is established and the cycle starts again with the changed contents of the pressure storage tank 1 with the condition according to
The process shown in
This procedure is in principle identical to the procedure described in the operating mode “Compression mode without post-compression” (2b to 2f) and is not explained further.
Depending on the application, the shifting container 60 can be directly connected to the gas source 5 and the shifting mechanism 61 can be equipped with the drive 8 of the working machine 4 so that no working machine 4 is required for pre-compression. In the following, this is referred to as “compression mode with post-compression”, even if the shifting device 6 is used to withdraw gas from the gas source 5 and to compress this same gas without using a working machine 4 in the pressure storage system.
The process shown in
After reaching the condition as shown in
The process described in
If necessary, the procedure shown in
Depending on the application, the shifting container 60 can be directly connected to the gas source 5 and the shifting mechanism 61 can be equipped with the output 8 of the working machine 4, so that no working machine 4 is required for pre-expanding. In the following, the term “expansion mode with pre-expansion” can be used, even if the shifting mechanism 6 is used to withdraw gas from the pressure storage tank 1 and to expand this gas without using a working machine 4 in the pressure storage system.
The pressure storage tank 1, the collecting basin 7 and other components such as the working machine 4 are not shown in
A multi-stage or serial arrangement makes sense in the operating modes “compression mode with post-compression” and “expansion mode with pre-expansion”. The advantages of feeding compressed gas to the pressure storage tank 1 or withdrawing compressed gas from the pressure storage tank 1 by means of the shifting device 6 have been explained in the previous text. However, the same shifting process can also be applied between two different pressure stages within the shifting device 6. In the following it is being spoken of a first and second stage, whereby further stages can be added according to the same principle.
Claims
1. A method for managing a pressure storage system with at least one pressure storage tank, the method comprising:
- filling the pressure storage tank with compressed gas; and/or
- withdrawing compressed gas from the pressure storage tank,
- wherein the pressure storage tank is partially filled with liquid and the rest of the volume is filled with compressed gas, wherein the charging of the pressure storage tank with a unit of compressed gas is accompanied by the withdrawal of a unit of liquid from the pressure storage tank, whereby the withdrawn unit of liquid is being used to displace the unit of compressed gas into the pressure storage tank by means of a shifting device consisting of at least one shifting mechanism and at least one shifting container, or vice versa the withdrawal of a unit of compressed gas from the pressure storage tank is accompanied by the charging of the pressure storage tank with a unit of liquid, whereby the unit of liquid is being used to withdraw the unit of compressed gas from the pressure storage tank by means of the shifting device, whereby the shifting of compressed gas into or out of the pressure storage tank is performed at low power when required, which means that no height difference between the pressure storage tank and the shifting device is necessary, and no hermetically sealed gas cushion in the pressure storage tank and/or in the shifting device is necessary, and for the shifting of the unit of liquid only the overcoming of a pressure difference caused by friction and flow losses as well as a pressure difference caused by a possibly existing height difference is necessary.
2. The method for operating a pressure storage system according to claim 1, wherein a working machine is used to compress gas using mechanical energy or vice versa to expand compressed gas by releasing mechanical energy which is provided or absorbed by a drive or output correspondingly, and wherein this working machine is fluidically connected to a gas source/sink, wherein from the shifting device on the side of the gas when required a fluidic connection to the working machine and/or the pressure storage tank is established and that on the side of the liquid when required a fluidic connection to the pressure storage tank and/or to the collecting basin is established by opening of respective valves in order to enable the shifting of liquid between the shifting device and the pressure storage tank or the collecting basin and in order to enable the shifting of gas between the shifting device and the pressure storage tank or the working machine at the same time.
3. The method for managing a pressure storage system according to claim 2, wherein the shifting device is operated inter alia with several, separate and/or combined shifting containers, which are mechanically or fluidically connected to one another and are arranged in parallel and/or serially.
4. The method for managing a pressure storage system according to claim 2, wherein the shifting device is used for compressing gas or expanding gas, respectively, by selectively shifting liquid between the shifting device and the pressure storage tank, the collecting basin or within the shifting device itself, i.e. between shifting containers.
5. The method for managing a pressure storage system according to claim 2, wherein liquid which is located within the shifting device, the pressure storage tank or the collecting basin is used as heat transfer medium and/or heat storage medium in order to supply or remove heat to or from the gas before, during and/or after the compression or expansion of gas, within a shifting container.
6. The method of managing a pressure storage system according to claim 2, wherein the heat exchange between the gas and the liquid within the shifting containers is increased by means of a regenerator to transfer heat from the gas to the liquid or to transfer heat from the liquid to the gas.
7. The method for managing a pressure storage system according to claim 2, wherein the pressure storage tank consists of at least two separate pressure containers and during the charging of the first pressure container with compressed gas, the liquid is displaced into a second pressure container, which is charged with compressed gas after the first pressure container has been charged, and the liquid is only displaced into the collecting basin during the charging of the last pressure container, wherein the procedure is the same when removing compressed gas from the pressure storage tank, in that the individual pressure containers are emptied one after the other.
8. A system for operating a pressure storage system, the system comprising:
- at least one pressure storage tank,
- a collecting basin both partly filled with a liquid and partly filled with gas,
- a working machine for converting compressed gas into mechanical energy and vice versa, connected to a gas source/sink,
- wherein a shifting device is present, with fluidic connections on the liquid side to the pressure storage tank and to the collecting basin and with fluidic connections on the gas side to the working machine and to the pressure storage tank, wherein the shifting device comprises at least one separate or combined shifting container, and valves for selectively shutting off one or more of the fluidic connections for gas or liquid, wherein no height difference between the pressure storage tank, the shifting device and/or the collecting basin is necessary, and wherein no hermetically sealed gas cushion in the pressure storage tank, in the shifting device and/or in the collecting basin is necessary, and wherein, in the case of the shifting compressed gas into or out of the pressure storage tank for the shifting of liquid, only the overcoming of a pressure difference caused by friction and flow losses as well as of a pressure difference caused by a possibly existing height difference is necessary.
9. The system for operating a pressure storage system according to claim 8, wherein the pressure storage system includes at least the following components:
- the pressure storage tank, partially filled with liquid and compressed gas, whereby these two media being openly adjacent to each other or separated from each other by a suitable separating device, namely by means of a bladder, piston or membrane, and a collecting basin,
- a shifting device, consisting of at least one separate or combined shifting container, wherein the media contained therein being openly adjacent to each other or separated from each other by a suitable separating device in the form of a bladder, a piston or a membrane, and a shifting mechanism for the displacement of liquid within the shifting device, i.e. between shifting containers and/or between the shifting device and the pressure storage tank or the collecting basin,
- a fluidic connection between the shifting device and the pressure storage tank for the at low power when required displacement of fluid between the shifting device and the pressure storage tank,
- a fluidic connection between the shifting device and the collecting basin for the at low power when required displacement of fluid between the shifting device and the collecting basin,
- a fluidic connection between the shifting device and the pressure storage tank for the at low power when required displacement of gas between the shifting device and the pressure storage tank,
- a fluidic connection between the shifting device and the working machine and/or the gas source/sink for the at low power when required displacement of gas between the shifting device and the working machine and/or the gas source/sink,
- controllable valves to define the flow directions of the fluid and gas during operation,
- a working machine, for compressing and/or expanding gas,
- an input/output drive for converting energy from any form of energy into mechanical energy in order to drive the working machine and, if necessary, the shifting mechanism or vice versa, suitable for receiving mechanical energy from the working machine and, if necessary, from the shifting mechanism and for converting and outputting it in any form of energy.
10. The system for operating a pressure storage system according to claim 9, wherein the shifting mechanism is integrated into the working machine or combined with the working machine or replaces it or forms one to several stages of it.
11. The system for operating a pressure storage system according to claim 9, wherein the shifting mechanism has a separate drive/output or is coupled to the drive/output of the working machine and consists of a piston or a pump.
Type: Application
Filed: May 16, 2019
Publication Date: Aug 12, 2021
Applicant: Green-Y Energy AG (Hasle bei Burgdorf)
Inventors: Rafik BARHOUMI (Hasle bei Burgdorf), Patrick BAUMANN (Olten), Dominik SCHNARWILER (Sursee)
Application Number: 17/055,978