DE102014004237A1 - Device for generating an electric current - Google Patents

Abstract

A device (1) for generating an electric current, which has at least one pressure vessel (4) for storing a gas under overpressure gas and at least one turbine (22) for driving a generator (2) is characterized in that the device ( 1) at least one mixing element (10) having at least one mixing chamber (12), at least one gas inlet (14) for introducing gas from the pressure vessel (4) into the mixing chamber (12), at least one liquid inlet (16) for introducing a liquid into the mixing chamber (12) and at least one outlet opening (20) and the mixing element (10) is formed such that the liquid is accelerated by the gas in the mixing chamber (12) so that it through the outlet opening (20) on the turbine (22).

Description

The invention relates to a device for generating an electric current having at least one pressure vessel for storing a gas under gas pressure and at least one turbine for driving a generator.

Such devices are known as parts of storage power plants, in particular of compressed air storage power plants, from the prior art.

In particular, in the generation of electricity by renewable energy, for example by wind or solar energy, the problem arises that the amount of electricity generated can not be adapted to the power requirements at certain times. The electricity can be generated, for example, during the use of solar energy via photovoltaic systems only during the day. When using wind power via wind turbines, electricity can only be generated if sufficient wind blows. Consequently, there is the problem of how the current generated at these times, which may not or not yet needed, can be cached.

This happens, for example, in so-called pumped storage power plants in which water is pumped into a reservoir located at a high level, for example a mountain lake or reservoir, with the electric current generated. If electricity is required at a later date, the water can drive turbines and generators via downpipes so that electricity can be generated again. The disadvantage is that such pumped storage power plants need a large water storage, which must be located much higher than the generator. This is not possible in all areas.

A form of energy storage which is also possible, especially in the lowlands, is the so-called compressed air storage power plants. Air is pumped with excess flow into a pressure vessel in which the pressure is thereby increased. If electrical power is required at a later date, the air is released from the tank and directed to a turbine that drives the generator. A disadvantage, however, is that during the compression of the air in the pressure vessel, this air is strongly heated. It is quite possible to achieve several hundred degrees Celsius of air temperature. The heat generated during the compression of the air must be dissipated and is often released into the environment unused. Now, if the air is relaxed again at a later time, the pressure in the interior of the pressure vessel thus lowered, it comes to a significant cooling of the air, if necessary, well below freezing. This can lead to icing of the entire system, so that the power generation does not work properly.

Conventionally, therefore, when expanding the pressurized gas, for example, natural gas is added and burned, so that the otherwise strong cooling is prevented and the required amount of heat is supplied. Alternatively, of course, external heat can also be added by other methods. However, this greatly reduces the efficiency of such compressed air storage power plants and also possibly leads to a further use of fossil fuels.

Under the product name "Adele", a compressed air storage power plant is currently being developed in which the heat generated during the compression of the air is stored in separate heat accumulators intended for this purpose in order to reuse it as the compressed air expands later. For this purpose, the heat storage, however, must be able to store large amounts of heat, for example, at over 600 ° C for at least several hours, which requires an immense amount of equipment.

From the US 8,539,763 B2 It is known from the air to be compressed and a liquid in which different additives are contained to form a foam, which can then be compressed or relaxed. As a result, a very good thermal contact between the gas to be compressed and the surrounding liquid is achieved.

The invention is therefore based on the object, so to develop a device for generating an electric current according to the preamble of claim 1 that it is simple, reliable and can be operated without much equipment.

The invention solves this problem by a generic device for generating an electric current according to the preamble of claim 1, which is characterized in that the device at least one mixing element with at least one mixing chamber, at least one gas inlet for introducing gas from the pressure vessel in the Mixing chamber, at least one liquid supply line for introducing a liquid into the mixing chamber and at least one outlet opening, wherein the mixing element is designed such that the liquid is accelerated by the gas in the mixing chamber such that it hits through the outlet opening on the turbine.

The inventive design of the device several advantages are achieved. The fact that the gas when expanding from the Pressure vessel comes into contact with the liquid, which has a certain temperature, the necessary during expansion of the gas to avoid icing heat amount of liquid can be removed. If, for example, air is used as the gas and water as the liquid, for example, the higher heat capacity of the water relative to the air causes the temperature of the water to decrease much more slowly than would be the case with air. In addition, during operation of the device, fresh liquid is permanently introduced into the mixing chamber, which removes the heat during expansion of the gas, thereby avoiding icing, in particular of the turbine. In addition, through the outlet opening of the mixing chamber, a mixture of the gas and the liquid, advantageously a mixture of air and water, emerges, which hits the turbine. Thereby, the high-efficiency turbines designed for driving by liquid can be used, whereby the efficiency of the device is further increased. The gas thus expands when leaving the pressure vessel and cools down. However, since it comes into thermal contact with the liquid having a temperature which is higher than that of the cooled or cooling gas, the cooled gas removes heat from the liquid. As a result, icing of the components involved is reliably avoided. In a particularly advantageous embodiment, the entire system with liquid reservoir and all components involved is operated almost adiabatically.

To the device, a compressor may be connected or be, through which the air is introduced into the pressure vessel or compressed in this. The gas overpressure may be, for example, 46 bar to 72 bar, in particular 60 bar. In principle, the maximum usable gas pressure is limited by the mechanical stability of the pressure vessel. If, for example, steel tubes are used as pressure vessels, as are also used in high-pressure lines or high-pressure gas lines, gas excess pressures of 200 bar and more can be achieved. This leads to a strong increase in the temperature of the gas. The resulting heat is advantageously dissipated and is optionally available for other applications. This can be done, for example, with heat exchangers known in principle from the prior art.

If the gas supplied from the pressure vessel to the mixing element, it may be useful to reduce the gas pressure to a respective operating pressure, which may be, for example, 10 bar. This can be done, for example, via reduction valves which are also known in principle from the prior art.

In a preferred embodiment of the device, the liquid feed line has a guide element which projects into the mixing chamber. It has been found to be advantageous if the guide element is a deflecting element projecting into the mixing chamber, in particular a deflection plate. This can be curved or obliquely formed, for example, with a curvature, for example, facing the convex side of the gas supply line.

The deflection element can also have further flow-conducting elements, which are arranged, for example, on the side of the deflection element facing the gas supply line. Through these elements, the flow resistance, which opposes the deflecting element to the gas flowing through the gas inlet, is reduced. This allows more energy from the gas to be used to accelerate the fluid accordingly.

Advantageously, the at least one mixing chamber is cylindrical and the at least one liquid feed line is arranged in a lateral surface of the mixing chamber. At one of the two end faces of the mixing chamber is in this case the outlet opening, while preferably at the opposite end, but optionally also in the lateral surface of the cylinder, the gas supply line is arranged.

Advantageously, the at least one liquid supply flow direction behind the at least one gas supply line is arranged. It is also possible to arrange the gas supply line and the at least one liquid supply line in the flow direction at the same height, so that the gas from the at least one gas supply line and the liquid from the at least one liquid supply lines of equal length travel within the mixing chamber.

Regardless of the exact configuration of the mixing chamber, the outlet opening is preferably a nozzle. This means that the outlet opening has a smaller cross section than the mixing chamber, so that the mixture of gas and liquid, preferably of air and water, which is produced in the mixing chamber, is accelerated again as it exits through the outlet opening before it strikes the turbine arranged behind it through which a connected generator can be driven. It ultimately generates the electrical current.

In a preferred embodiment of the device, the at least one liquid feed line is connected to a liquid reservoir. The liquid reservoir is preferably under a liquid overpressure. The liquid overpressure is greater than the surrounding Atmospheric pressure. By using such a liquid reservoir, it is also possible to use the liquid in a circuit. After the mixture of gas and liquid has hit the turbine, the liquid, for example water, is returned to the reservoir. The reservoir can be a tank or a cavern but also a lake, reservoir, river or a sea. Since, unlike pumped storage power plants, the water pressure is not the decisive factor for power generation, in this way it is also possible to profitably use only small liquid overpressures. Particularly in the case of a very large reservoir, for example in the form of a natural or artificially created reservoir, the amount of heat taken from the water during the expansion of the gas does not lead to any appreciable cooling of the reservoir.

Preferably, the released in the compression of the gas heat is supplied to the liquid reservoir. In particular, in the case of a particularly large reservoir, this does not lead to a significant change in the temperature of the liquid. Overall, in this case, therefore, both the compression and the expansion of the gas can be almost isothermal. The overall system with liquid reservoir and all components involved preferably represents at least almost adiabatic, in the optimal case as completely adiabatic dar. This is preferably independent of what happens with the heat generated during the compression of the gas. This can be used as waste heat unexploited or stored, for example, and then be used again during expansion of the gas. In particular, a large liquid reservoir offers itself as storage.

A storage of extremely large amounts of heat at very high temperatures is therefore not necessary. It therefore also eliminates the components that have to withstand high thermal loads partially withstand extreme pressures. The construction of such a device is therefore considerably simplified compared with a device of the prior art and reduces the manufacturing costs.

The liquid overpressure is preferably smaller than the gas overpressure. The higher the gas overpressure is formed, the greater the amount of gas that can be stored in a given volume. This achieves high storage densities and high energy densities.

In an advantageous embodiment of the device, the device has an adjusting device, by means of which a mixing ratio between gas and liquid in the mixing chamber, preferably during operation of the device, is adjustable. This is done for example via reduction valves and / or a pump, by which the amount of inflowing liquid, which can be adjusted by the at least one liquid feed into the mixing liquid, which is introduced by the at least one liquid feed into the mixing chamber. Depending on the existing gas overpressure or the set operating pressure of the gas introduced through the at least one gas supply line, different amounts of liquid are optimal. By the adjustment means, the optimum ratio between gas and liquid in the mixing chamber can be achieved for each of the set pressures, whereby the efficiency of the device is further increased.

Advantageously, the turbine is a Pelton turbine. This turbine has a particularly high efficiency, especially when using a liquid as a drive medium. Of course, the use of other turbines, such as a Francis turbine is possible.

In order to be able to optimally use the accelerated mass of the mixture of gas and liquid which emerges from the outlet opening of the mixing chamber, the turbine is advantageously surrounded by a housing. This is preferably located as close as possible to the wings of the respective turbine in order to reduce as much as possible the proportion of the gas-liquid mixture which does not hit the turbine blades. For this purpose, it may also be useful to arrange beam shaping elements at the outlet opening or to give the outlet opening itself a jet-shaping shape.

The invention also solves the problem posed by a mixing element for a device described here.

With a mixing element described here, which can be formed for example as a jet nozzle, an efficiency of 95% can be achieved. This means that 95% of the kinetic energy initially contained in the gas can be transferred to the liquid in the mixing chamber.

As a result, a compressed air storage power plant can be achieved, which can be operated isothermally or at least almost isothermally and / or adiabatically, without, for example, having to additionally supply energy through the combustion of fossil fuels. The design is very simple and has in particular compared to the current tested device "Adele" a variety of design advantages, in particular, no thermally highly stressed components must be developed and installed and also specially developed for Adele heat exchanger are not needed. The components used for the device described here are known per se from the prior art almost all known and developed for mass production and highest efficiency. A further advantage of the device described here is that the at least one pressure vessel in which the gas is stored can be produced and used in virtually any desired size. In addition to high-pressure tanks, which are manufactured especially for this application, natural caverns, for example, in rocks or salt flats or undersea water bubbles can be used. Therefore, the pressure vessels are almost arbitrarily scalable and also the amount of electricity or electrical power that can be generated by the device can be adapted to the respective needs. In particular, in underwater or otherwise underwater pressure vessels arranged in which the applied pressure is applied by the water column located above the container, there is the advantage that this pressure, regardless of the level of the pressure vessel in which the gas is compressed, almost or advantageously even completely remains constant. While in rigid overpressure containers, such as caverns or containers, the pressure within the container increases upon compression of the gas and decreases upon expansion of the gas, in pressure vessels in which the pressure is applied by a water column disposed above the container, regardless of the amount of gas filled the gas should always be used under the same high pressure.

In a preferred embodiment, the device is set up to be operated in a pulsed mode. The device has in particular a closure device for closing the outlet opening, as well as a gas supply valve and a liquid supply valve. In pulsed operation, the outlet opening of the mixing chamber is now closed by the closure device. The liquid supply valve is opened while the gas supply valve is closed. In this state, liquid is thus introduced into the mixing chamber, while gas can not penetrate. Once the mixing chamber is filled to a predetermined degree, for example, up to one-half, three-quarters or full, the liquid supply valve is closed to prevent liquid from being forced out of the mixing chamber through the liquid supply line. Subsequently, the gas supply valve and closing device for the outlet opening are opened, so that the liquid located in the mixing chamber is forced out of the mixing chamber by the gas emerging from the gas inlet line and expanding, leaving it through the outlet opening. In this case, for example, the closure device for the outlet opening and the gas supply valve can be opened simultaneously. Alternatively, it is also possible to first open the gas supply valve and only a predetermined period later to open the closure device for the outlet opening.

After a predetermined period of time, within which a predetermined proportion of the liquid located in the mixing chamber has left the mixing chamber, the gas supply valve and the closure device for the outlet opening is closed. This can also be done simultaneously or successively, wherein advantageously first the gas supply valve and then the closure device is closed. Now, the liquid supply valve is opened and again introduced liquid into the mixing chamber. This method can be cyclically operated so that the device is operable in a pulsed mode.

In a preferred embodiment of the device, the device has an electrical control which is set up to carry out such a method. It is advantageously arranged to control a gas supply valve, a liquid supply valve and / or a closure device for the outlet opening of the mixing chamber and to open and / or close by control signals.

With the aid of a drawing, an embodiment of the present invention will be explained in more detail below. It shows

1 - The schematic representation of a device according to a first embodiment of the present invention with generator disposed therein and

2 - A schematic sectional view through a mixing element.

1 shows the schematic representation of a device 1 according to a first embodiment of the present invention, to which a generator 2 is arranged. In a pressure vessel 4 there is a gas, in particular air, at a gas pressure. The pressure vessel 4 is via a pressure line 6 with a compressor 8th connected. Excessive power generated, for example, by regenerative energy sources, but not currently needed, can be used to drive the compressor 8th be used so that air through the pressure line 6 in the pressure vessel 4 is pressed. This increases the gas pressure inside the pressure vessel 4 at.

The device 1 also has a mixing element 10 with a mixing chamber 12 one gas supply 14 and a liquid supply line 16 , About the gas supply 14 can gas out of the pressure vessel 4 into the mixing chamber 12 be initiated. For this purpose, valves or other adjustment may be present in order to adjust the amount of incoming gas can. About the liquid supply 16 which is connected to a liquid reservoir, can liquid in the mixing chamber 12 be initiated. The mixing element 10 also has an outlet opening 20 through a mixture of water and air or liquid and gas from the mixing chamber 12 can escape. It then hits a turbine 22 which is thereby rotated and the generator 2 drives. The liquid on the turbine 22 is taken, is via a return line 24 again the liquid reservoir 18 , which may be a lake or river, for example.

Preferably, the liquid from the liquid reservoir 18 via the liquid supply line 16 under a liquid overpressure standing in the mixing chamber 12 initiated. This can be done by the compressor 8th via a second pressure line 26 about which he deals with the fluid reservoir 18 connected, apply the required liquid pressure.

When compressing the gas in the compressor 8th the gas is heated. The amount of heat released is particularly dependent on the gas pressure and can to temperatures of several hundred degrees Celsius within the pressure vessel 4 lead if the heat is not dissipated. Therefore, in the 1 shown embodiment, a dashed heat removal line 32 present the compressor 8th with the liquid reservoir 18 combines. In a structurally particularly simple embodiment, liquid from the liquid reservoir 18 to the compressor 8th passed there and absorbs the resulting from the compression of the gas and released heat. Through the heat removal line 32 the liquid thus heated is returned to the liquid reservoir. The resulting heating of the liquid in the liquid reservoir 18 In addition to the liquid used, of course, the size of the liquid reservoir 18 and optionally the thermal insulation of the liquid reservoir 18 dependent. Used as a liquid reservoir 18 For example, a thermally insulated and insulated cavern or a pressure vessel used, the from the compressor 8th over the heat removal line 32 dissipated heat in the liquid reservoir 18 get saved.

When expanding the gas in the pressure vessel 4 is stored, it comes to a cooling of the environment, since the gas absorbs heat during expansion. This is via the liquid from the liquid reservoir 18 passing through the liquid supply line 16 into the mixing chamber 12 initiated, provided. The better the thermal insulation of the liquid reservoir 18 The less the original was the liquid discharge line 32 the liquid reservoir 18 Heat supplied has been lost and must now be replaced by other means.

Becomes the liquid reservoir 18 chosen large enough and designed, for example, as an artificial reservoir or natural lake, which leads from the compressor 8th over the heat removal line 32 Dissipated heat does not lead to a significant increase in temperature of the liquid in the liquid reservoir 18 so that the entire process of compressing, storing and expanding the gas can be isothermal or at least nearly isothermal. As a result, the components used thermally hardly loaded, making them easier and cheaper to produce.

2 shows the schematic sectional view through the mixing element 10 out 1 , You can see the mixing chamber 12 , the gas supply 14 as well as the liquid supply 16 , At the in 2 right end of the mixing chamber 12 is the exit opening 20 that's here as a nozzle 28 is trained. In the in 2 the embodiment shown, the flow direction of the mixing chamber extend 12 , in the 2 from left to right, and the flow direction within the liquid supply line 16 at a right angle to each other. Therefore, it is advantageous if as in 2 shown a deflecting element 30 into the mixing chamber 12 protrudes. Liquid, especially water, through the liquid supply 16 in 2 from bottom to top in the mixing chamber 12 flows in, is through the deflecting element 30 at least partially deflected, so that the flow direction contains at least one component which is in the direction of the outlet opening 20 is directed. Depending on the size and design of the deflecting element 30 and the liquid overpressure with which the liquid passes through the liquid feed line 16 into the mixing chamber 12 flows in, this component is more or less large. In the gas supply 14 and / or the liquid supply line 16 Valves may be present, by which the respective amount of the inflowing medium can be reduced or increased, so that the optimum mixing ratio between gas and liquid inside the mixing chamber 12 can be adjusted.

LIST OF REFERENCE NUMBERS

1

contraption

2

generator

4

pressure vessel

6

pressure line

8th

compressor

10

mixing element

12

mixing chamber

14

gas supply

16

liquid supply

18

liquid reservoir

20

outlet opening

22

turbine

24

Return line

26

Second pressure line

28

jet

30

deflecting

32

Wärmeabführleitung

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 8539763 B2 [0008]

Claims (9)

Contraption ( 1 ) for generating an electric current, the at least one pressure vessel ( 4 ) for storing a gas under gas pressure and at least one turbine ( 22 ) for driving a generator ( 2 ), characterized in that the device ( 1 ) at least one mixing element ( 10 ) with at least one mixing chamber ( 12 ), at least one gas supply line ( 14 ) for the introduction of gas from the pressure vessel ( 4 ) into the mixing chamber ( 12 ), at least one fluid supply line ( 16 ) for introducing a liquid into the mixing chamber ( 12 ) and at least one exit opening ( 20 ), wherein the mixing element ( 10 ) is formed such that the liquid by the gas in the mixing chamber ( 12 ) is accelerated so that it passes through the outlet opening ( 20 ) on the turbine ( 22 ) meets. Contraption ( 1 ) according to claim 1, characterized in that the at least one liquid feed ( 16 ) has a guide element, which in the mixing chamber ( 12 ) protrudes. Contraption ( 1 ) according to claim 2, characterized in that the guide element into the mixing chamber ( 12 ) projecting deflecting element ( 30 ), in particular a baffle, is. Contraption ( 1 ) according to one of the preceding claims, characterized in that the at least one mixing chamber ( 12 ) is cylindrical and the at least one liquid supply ( 16 ) in a lateral surface of the mixing chamber ( 12 ) is arranged. Contraption ( 1 ) according to one of the preceding claims, characterized in that the at least one liquid feed line ( 16 ) with a liquid reservoir under liquid pressure ( 18 ) connected is. Contraption ( 1 ) according to claim 5, characterized in that the liquid pressure is less than the gas pressure. Contraption ( 1 ) according to one of the preceding claims, characterized in that the device ( 1 ) has an adjusting device, by which a mixing ratio between gas and liquid in the mixing chamber ( 12 ), preferably also during operation of the device ( 1 ), is adjustable. Contraption ( 1 ) according to one of the preceding claims, characterized in that the turbine ( 22 ) is a Pelton turbine. Mixing element ( 10 ) for a device ( 1 ) according to any one of the preceding claims.

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