AT518299B1 - Process for regasifying cryogenic liquefied gas - Google Patents

Abstract

In a process for regasifying cryogenic liquefied gas, such as e.g. Methane or air, in which a subset of the in a tank (1) located cryogenic liquefied gas from the tank (1) via a pressure lock an evaporator (17) is supplied, in which evaporates the subset, whereupon the vaporized gas in a high-pressure gas storage (39 ), is fed into a pipeline network or fed to an energy converter for generating electrical energy, the pressure lock comprises two chambers (27,28) which are alternately filled with a subset of the cryogenic liquefied gas from the tank (1), wherein the with Subset filled chamber (27,28) after the respective filling of the tank (1) separated and connected to the evaporator (17), whereupon a pressure equalization between the evaporator (17) and the chamber connected thereto (27,28) established. Subsequently, at least one displacement body (21, 22) is displaced in such a way that the gas contained in the chamber (27, 28) which is under evaporator pressure is at least partially displaced into the evaporator (17).

Description

Description The invention relates to a method for regasifying cryogenic liquefied gas, e.g. Methane or air, in which a part of the cryogenic liquefied gas in a tank is fed from the tank via a pressure lock to an evaporator, in which the part evaporates, whereupon the evaporated gas is filled into a high-pressure gas storage, fed into a pipeline network or an energy converter for generation electrical energy is supplied.

[0002] Gases liquefied at low temperatures are becoming increasingly important. They are transported and stored at low pressure. The use generally requires the conversion from the liquid state to the gas phase. For further use in the high-pressure area, the product is stored at the place of use in low-pressure tanks (e.g. max. 37 bar) and then regasified the cryogenic liquefied gas. For this purpose, it is placed in evaporators, in which the evaporation takes place with the addition of energy. The high pressure phase previously requires high pressure pumps for cryogenic liquids that push the liquids into the evaporator. The pump supplies the compression and evaporation energy with the evaporator.

Alternatively, the compression can be done with a compressor. For this purpose, the liquid is converted into the gas phase at tank pressure before compression in the evaporator and then compressed with the compressor.

Both procedures are energy-intensive processes that require maintenance-intensive machines with high investment costs. So far, this application has been limited to a few systems, which as a whole are economically insignificant. With increasing market penetration of natural gas refueling (this has so far been carried out with conventional compressors), new gas supply solutions have to be found. With compressors, all of the compression energy must be supplied via the power grid and the supply gas lines must have the required productivity. Both are only partially available.

The alternative is LNG, cryogenic liquefied natural gas. The liquefied gas is transported to the end user or to the petrol station in special, insulated tankers. There it is stored in special tanks and has to be regasified and compressed. So far, this requirement in the high-pressure range can only be met with known high-pressure piston pumps. The main disadvantage of the piston pump is that it shows signs of wear after a relatively short period of time, which leads to gas slip, which is extremely dangerous from an ecological and safety point of view, for example with methane, and high maintenance costs have to be planned. In addition, the driving motor requires external energy (electricity).

The documents WO 2007/128023 A1 and WO 2013/182907 A2 describe methods for regasifying cryogenic liquefied gases which allow the process to be continued by relieving or throttling the storage tank. Both methods do not require electricity for compression. The necessary re-liquefaction, but only a very small part of the regasified product, is, as mentioned, solved by pressure relief or throttling.

In the known methods for regasifying cryogenic liquefied gas, the liquid phase of the gas liquefied by cold is stored in an insulated tank. From this it has to be brought into the high-pressure section for evaporation, so that the gas pressure is set as a function of the amount of liquid product supplied, the volume of the evaporation space and the corresponding energy supply. The tank has a much lower pressure than the evaporator, which is under high pressure. Both systems must therefore be connected to one another via a so-called pressure lock. A dosing reservoir was used as the pressure lock in the processes according to the documents WO 2007/128023 A1 and WO 2013/182907 A2.

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AT518 299 B1 2018-03-15 Austrian

Patent office A disadvantage of the methods mentioned is that a relatively high proportion of energy must be used to re-liquefy part of the regasified product.

The present invention therefore aims to provide a process for the regasification of cryogenic liquefied gases which requires a smaller amount of product to be reliquefied and / or in which the energy required for the reliquefaction can be reduced.

To achieve this object, the invention in a method of the type mentioned essentially consists in the fact that the pressure lock comprises two chambers which are filled alternately with a portion of the cryogenic liquefied gas from the tank, the chamber filled with the portion after the respective filling process, it is separated from the tank and connected to the evaporator, whereupon a pressure equalization between the evaporator and the chamber connected to it is established, and that at least one displacement body is then displaced such that it is contained in the chamber under evaporator pressure Gas is at least partially, preferably completely, displaced into the evaporator and the other chamber is filled with a portion of the cryogenic liquefied gas from the tank. Because at least one displacement body is provided, the amount of the regasified product remaining in the respective chamber after the pressure equalization with the evaporator is pressed into the store. The fact that the amount of the regasified product remaining in one chamber is squeezed out during the displacement of the displacement body and at the same time new liquid product is filled in from the tank in the other chamber can be ensured in a simple and reliable manner. The displacement body can be guided displaceably in a cylinder, the displacement body dividing the cylinder into the two chambers, so that both chambers are realized in the same cylinder. Alternatively, the first and the second chamber can each be formed in a separate cylinder, in each of which an associated displacement body is slidably guided. In this context, a preferred embodiment provides that each chamber is assigned its own displacement body, the displacement bodies being moved synchronously to simultaneously displace the gas from one chamber into the evaporator and to fill the other chamber with cryogenic liquefied gas from the tank.

A preferred embodiment provides that the two chambers are alternately connected to the tank and to the evaporator. This means that one chamber is first connected to the tank and filled with liquid product from the tank and then separated from the tank and connected to the evaporator. After pressure equalization with the evaporator, the amount of gas or liquid remaining in the chamber is squeezed out and the process can begin again, i.e. the chamber can be filled with liquid product from the tank again. The other chamber is also connected alternately to the tank and the evaporator in an analogous manner, but the individual steps take place at different times from the other chamber.

A particularly economical procedure is made possible if the liquefied gas is preferably moved from the chamber into the evaporator under the geodetic pressure. Alternatively, the required pressure difference can also be applied or supported by a circulation pump. The filling of the chamber advantageously includes the establishment of a pressure equalization between the tank and the chamber. In order to enable the chamber to be filled under the geodetic pressure of the tank, it is preferably provided that the liquid inlet into the chamber is arranged lower than the liquid outlet from the tank.

The gas is preferably moved from the chamber into the evaporator via a heat exchanger in which heat is supplied to the liquid gas. The required heat, or a part thereof, can be extracted from a gas stream to be liquefied in order to enable it to condense and be returned to the tank.

A particularly energy-efficient procedure is guaranteed if, like this

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AT518 299 B1 2018-03-15 Austrian patent office corresponds to a preferred training, the pressure after the pressure equalization between the

Evaporator and the chamber connected to it is in the supercritical range.

The displacement of the displacement body or bodies can in principle be done with any drives, such as with an electric drive. However, the drive is advantageously carried out hydraulically or pneumatically, in particular with the aid of a fluid pressure generated from the process itself. In this case, the procedure is preferably such that the displacement of the displacement body or bodies takes place by applying gas pressure, in particular gas pressure from a high-pressure gas store fed by the evaporator.

The pneumatic actuation is preferably carried out via a separate piston. In this context, a preferred procedure provides that an actuating piston is displaceable in an actuating cylinder and is mounted for synchronous movement with the displacement body (s), and the displacement of the displacement body (s) is caused by one-sided loading of the actuating piston with the one preferably generated in the system Gas pressure occurs after or while there is (is) a pressure release on the opposite side of the actuating piston. The gas pressure required for the shift is preferably stored in a separate store and, if necessary, filled from the system or called into the system.

The pressure release is preferably carried out by the fact that the gas on the opposite side of the actuating piston is preferably cooled to condensation and then expanded and is returned to the tank as a liquid and liquid / gas phase or only as a gas phase ,

A particularly energy-efficient procedure for liquefying the gas in connection with the pressure release provides that the gas is led to its cooling and condensation via the heat exchanger and is cooled in heat exchange with the liquid led from the chamber into the evaporator, the condensation is preferably carried out in the heat exchanger up to a point in the T, s diagram which is to the left of the critical point. It is advantageous if the pressure remains constant.

The method according to the invention for the regasification of cryogenic liquefied gas can preferably be used in a method for the demand-dependent regulation and delivery of the electrical output power of an energy converter operated with regenerative energy, in particular an electrical generator. For energy converters operated with regenerative energy, e.g. In the case of energy converters driven by wind energy, solar energy or tidal energy, there is the problem that the generation of electrical energy, which is dependent on external conditions, cannot readily be brought into line with the respective demand. For example, energy generation in solar systems relies on sunlight, with a first peak in energy consumption usually occurring when electrical lighting fixtures are switched on after sunset. In the case of energy sources which, to make matters worse, their performance is not readily predictable, and especially when using wind energy, these disadvantages become particularly clear when using regenerative energy sources.

For the purpose of equalizing or smoothing the electrical output power of such energy converters operated with regenerative energy, it has already been proposed to store the energy generated in times of lower demand accordingly. The energy can e.g. be stored in the form of a liquefied gas, as described in AT 506779 B. For this purpose, the electrical energy supplied by the energy converter is used to liquefy a gas. The gas is stored in liquefied form and can be regasified using comparatively simple devices, the energy released due to the increase in volume during the regasification being converted into electrical energy in a simple and conventional manner and made available to electrical consumers. The method is preferably suitable for the use of air or components thereof, e.g. Nitrogen, or other gases, e.g. Methane, as a storage medium.

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AT518 299 B1 2018-03-15 Austrian Patent Office [0021] However, the efficiency achieved by the method described in AT 506779 B has proven to be unsatisfactory. In addition, in the case of the process described in AT 506779 B and in other similar processes, it was assumed that at the moment the

Air liquefaction electricity is available such that the operation of the air liquefier or

Air separator can be done at the optimal point. However, that seems unrealistic.

If one considers the calculation of the efficiency in more detail, one always starts from the incorrectly applied ratio of stored current to current fed into the network, instead of calculating the realistic ratio of the wind turbine / photovoltaic panel generated to the current fed into the network. Storage by means of liquefaction only makes sense if an electrical efficiency that is well above 50% is achieved. Apart from the pumped storage plant and its modifications, no solutions are known to date for this. The disadvantage of the pumped storage power plant is that it is bound to precise geological conditions that are only available to a limited extent.

In a non-claimed embodiment, therefore, a method for storing and supplying the electrical energy generated by an energy converter operated with regenerative energy, which is characterized by a higher efficiency, is to be created.

Here, a method for demand-based control and delivery of the electrical output power of an energy converter operated with regenerative energy, in particular electrical generator, is provided, wherein a gas, in particular air, is liquefied in a device coupled to the energy converter, the liquefied gas preferably without pressure is stored in a tank and the liquefied gas is regasified if necessary and energy released from the gas is converted into electrical energy and made available to electrical consumers, the conversion of the energy released into electrical energy comprising the following steps:

- Driving a pressure increasing device by means of the pressure of the regasified gas, - Using the pressure increasing device to compress a liquid medium, for example water, and to press it into a turbine, - Driving an electric generator with the help of the Turbine to receive electrical energy.

Furthermore, a method for utilizing energy stored in cryogenic liquefied gas is provided according to a non-claimed embodiment, in which the liquefied gas stored in a tank is regasified and energy released from the regasified gas is converted into electrical energy and available to electrical consumers The conversion of the energy released into electrical energy comprises the following steps:

- Driving a pressure increasing device by means of the pressure of the regasified gas, - Using the pressure increasing device to compress a liquid medium, for example water, and to press it into a turbine, - Driving an electric generator with the help of the Turbine to receive electrical energy.

The regasification of the liquefied gas can be carried out in a particularly advantageous manner with a method according to the invention.

The gas pressure resulting from the regasification of e.g. > 200 bar, is relieved via a turbine if necessary. In contrast to AT 506779 B, however, there is no direct relaxation, but indirect use of the energy released from the gas. With the gas pressure a pressure increasing device, e.g. a piston driven that

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AT518 299 B1 2018-03-15 Austrian patent office instead of gas a liquid medium, e.g. water in an expansion machine, e.g.

a turbine, pushes. The expansion machine is coupled to a generator, so that electricity is generated as required.

The expansion machine is coupled to a generator, so that electricity is generated as required.

The liquid medium, for example water, is preferably expanded to atmospheric pressure by the expansion machine, a preferred embodiment of the method providing that the liquid medium, for example water, expanded in the expansion machine is returned to the pressure-increasing device. The returned liquid medium is then compressed again in the pressure increasing device. The liquid medium is thus circulated.

To drive the pressure increasing device, the regasified, high pressure gas is preferably a drive chamber, such as e.g. a drive cylinder of the pressure increasing device, wherein the gas located in the drive chamber preferably drives a piston which drives or is coupled to a pressure increasing means acting on the liquid medium. The pressure increasing means can in turn comprise a piston of a piston pump.

The pressure increasing device thus preferably has a drive element acted upon by the high pressure gas, such as e.g. a piston, and pressure-increasing means acting on the liquid medium, the drive element driving the pressure-increasing means.

[0038] After the high-pressure gas has emerged from the pressure-increasing device, the gas is preferably passed through a heat exchanger. At the outlet, a residual pressure of the gas is preferably maintained, which is in the Ts diagram to the left of the critical point. In the heat exchanger, the gas is preferably cooled at constant pressure (preferably to the left of the critical point in the Ts diagram), so that part of the gas is liquefied.

Furthermore, it is advantageous if the gas cooled in the heat exchanger is expanded via a throttle point in the tank. The gas is liquefied in the tank using the JouleThomsen effect and is available again for the regasification process.

This method makes it possible to decouple the network requirement from the direct generation on the wind turbine or the photovoltaic system or the like and to supply the network exclusively from the liquid gas storage. Is the power on the energy converter operated with renewable energy, e.g. too low on the wind turbine, the condenser is operated in standby mode. If the electricity generated by the energy converter rises above the possible efficiency, the condenser is switched on. The prerequisite for this is that the efficiency allows electricity generation that exceeds the losses.

Furthermore, the method for utilizing energy stored in cryogenic liquefied gas allows inexpensive storage of the energy in the form of liquefied gas and a demand-oriented conversion of the energy stored therein into electrical energy.

[0042] The liquid gas can be used, for example, to generate electricity in a motor vehicle. There is a vacuum-insulated low-pressure tank in the vehicle in which the liquid is filled. If necessary, the liquid can be regasified and an energy conversion into electrical energy can be carried out.

The vehicle runs as usual with a battery that can be small but powerful. The driving cycle is shown via the battery. If the voltage and current in the battery have dropped to a lower limit, the electricity generation based on the liquefied gas starts and charges the battery while driving or while standing. A different stationary charging of the battery is no longer necessary because the charging process takes place while driving. Air is released as “exhaust gas.

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AT518 299 B1 2018-03-15 Austrian Patent Office According to one aspect, an apparatus for regasifying cryogenic liquefied gas is provided, comprising a tank for the cryogenic liquefied gas, an evaporator and a pressure lock arranged between the tank and the evaporator , which is characterized in that the pressure lock comprises two chambers which can be filled alternately with a subset of the cryogenic liquefied gas from the tank and which can be separated from the tank and connected to the evaporator after the respective filling process, and that at least one displacement body is provided is arranged to displace the gas contained in the chamber under evaporator pressure into the evaporator.

A preferred embodiment (FIG. 1) provides that the at least one displacement body is designed as a displacement piston which is displaceably mounted in a cylinder.

Another preferred embodiment provides that the two chambers are each connected to the tank and to the evaporator via shut-off devices, so that they can be connected alternately to the tank and to the evaporator.

Each chamber advantageously has its own displacement body, the displacement bodies of both chambers being indissolubly coupled to one another for synchronous movement.

Preferably, the displacement body, in particular as a displaceably mounted displacement piston in a respective cylinder, is coupled to an actuating piston displaceably mounted in an actuating cylinder for synchronous movement.

For actuating the actuating piston, an advantageous embodiment provides that at least one line which can be acted upon by gas pressure opens into the actuating cylinder, so that the displacement of the displacement body or bodies is effected by acting on the actuating piston with the gas pressure on one side.

In particular, two lines are provided on both sides of the actuating piston which open into the actuating cylinder and can each be acted upon by the gas pressure.

According to a preferred embodiment it is provided that the line connecting a chamber and the evaporator in each case leads via a heat exchanger.

In order to keep the fluid in the tank and in the pressure lock in a liquid state, it is preferably provided that the tank and the chambers of the pressure lock are thermally insulated.

[0053] Furthermore, the volume of the chambers is preferably smaller than the volume of the evaporator.

Furthermore, an unused device for utilizing potential energy stored in cryogenic liquefied gas can be provided, comprising a tank for storing the liquefied gas, a regasification device connected to the tank for regasifying the liquefied gas, an energy converter for converting the gas Regasifying released energy into electrical energy, the electrical energy supplied by the energy converter being made available to electrical consumers, the energy converter comprising a pressure increasing device which can be driven by the pressure of the regasified gas, the pressure increasing device being arranged around a liquid supplied to the pressure increasing device To compress medium, for example water, the energy converter further comprising an expansion machine, in particular a turbine, to which the pressure-increasing device is connected in order to expa nsionsmaschine to supply the compressed liquid medium, and wherein the energy converter further comprises an electrical generator which can be driven by the expansion machine.

[0055] The pressure increasing device is preferably designed as a pump, in particular a piston pump.

[0056] The expansion machine is preferably connected to the printer 6/15 via a return line

AT518 299 B1 2018-03-15 Austrian patent office connected to the elevation device in order to return the liquid medium, e.g. water, which has been expanded in the expansion machine, to the pressure increase device, preferably through the inlet above the geodetic height.

[0057] The drive side of the pressure increasing device is preferably connected to a heat exchanger in order to conduct the gas leaving a drive chamber of the pressure increasing device through the heat exchanger.

Preferably, the heat exchanger is connected to the tank via a throttle point in order to supply the gas cooled in the heat exchanger to the tank.

The regasification device is particularly preferably designed in accordance with the above-described device for the regasification of cryogenic liquefied gas.

The device described above for utilizing energy stored in liquefied gas can be used particularly advantageously in the following context, namely in a device for demand-based regulation and delivery of the electrical output power of an energy converter operated with regenerative energy, in particular an electrical generator, comprising a with the energy converter coupled gas liquefaction device, a tank for storing the liquefied gas and the device for converting the energy stored in the cryogenic liquefied gas into electrical energy.

The invention is explained in more detail below with reference to an exemplary embodiment shown schematically in the drawing. 1 shows a block diagram of a regasification system for the purpose of pressure storage and [0063] FIG. 2 shows a block diagram of a system for demand-dependent regulation and delivery of the electrical output power of an energy converter operated with regenerative energy.

1 comprises a vacuum-insulated tank 1 in which cryogenic liquefied gas, e.g. Methane or another cryogenic liquefied gas. The tank 1 is connected via a line 2 and shut-off devices 3 and 4 either to the inlet 5 of the cylinder 6 or the inlet 7 of the cylinder 8. The cylinders 6 and 8 are thermally insulated, in particular vacuum insulated. The gas drop 9 of the cylinder 6 and the gas drop 10 of the cylinder 8 are each connected to the gas space of the tank 1 via a shut-off device 11 or 12. The inlet 5 of the cylinder 6 and the inlet 7 of the cylinder 8 are each connected to an evaporator 17 via a shut-off device 13 or 14, a line 15 and a heat exchanger 16. The gas drop 9 of the cylinder 6 and the gas drop 10 of the cylinder 8 are each connected to the evaporator 17 via a shut-off device 18 or 19 and a line 20.

In the cylinder 6, a displacement piston 21 is slidably mounted and in the cylinder 8, a displacement piston 22 is slidably mounted. The two pistons 21, 22 are connected to one another by means of a rigid connection on the rod 23 and are thus mounted so that they can be moved together. The outer chambers 25 and 26 of the cylinders 6 and 8 are constantly connected to one another during operation, which is done, for example, by means of an axial pressure compensation bore 24. The inner chambers 27 and 28 of the cylinders 6 and 8 are those chambers of the cylinders 6 and 8 which can be filled with fluid from the tank 1 via the inlet 5 or 7.

To actuate the displacement pistons 21 and 22 in the direction of the double arrow 30, an actuating piston 40 is displaceably guided in a cylinder 29 and rigidly connected to the rod 23. At its opposite ends, the cylinder has inlets or outlets 30 and 31, via which pressure medium can be supplied on one side, while pressure relief is carried out on the other side. For the supply of pressure medium, the inlets and outlets 30 and 31 are connected to a pressure accumulator 34 via shut-off elements 32 and 33. To relieve pressure, the inlets and outlets 30 and 31 are via shut-off devices 35

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AT518 299 B1 2018-03-15 Austrian patent office and 36, a line 37 and the heat exchanger 16 connected to the gas space of the tank 1.

A gas bottle 39 is connected to the evaporator via a shut-off device 38 and can be filled with the medium regasified in the evaporator 17 and then transported away. The pressure container 34 can also be fed by the evaporator 17.

The operation of the regasification system shown in Fig. 1 is now as follows. From the vacuum-insulated tank 1, the liquefied gas flows into the chamber 27 solely by the geodetic pressure. For this purpose, the shut-off device 3 is opened and a connection to the gas space of the tank 1 is established by opening the shut-off device 11 (gas decrease). If the chamber 27 is filled and the gas that may be formed flows out of the chamber 27 into the tank 1, the chamber 27 is separated from the tank 1 by closing the shut-off elements 3 and 11. Now the connection to the evaporator 17 is established by opening the shut-off element 13. Here, too, there is a gas drop from the evaporator outlet via the line 20 to the gas drop 9 of the chamber 27 by opening the shut-off member 18, which creates a pressure compensation and enables the chamber 27 to be emptied quickly by the geodetic pressure.

Between chamber 27 and evaporator 17 is a heat exchanger 16 in a row intermediate store. The product flows through the geodetic pressure from the chamber 27 first into the heat exchanger 16 upstream of the evaporator 17. This is located below the chamber 27, but above the evaporator 17. Therefore, the liquid only flows into the heat exchanger 16 by the geodetic pressure and fills it , Excess product flows through this into the evaporator 17 located there, where there is a sudden evaporation, so that the product can continue to flow until the chamber 27 is emptied.

In the chamber 27, the same pressure is set as in the evaporator 17. In the chamber 27 there is the piston rod 23 on which the pistons 21, 40 and 22 are located. It is assumed that the piston 21 is in the end position on one side of the chamber. The piston 21 is driven by the piston 40, which on the other side also moves a piston 22 with the same function. The piston 40 is acted upon by the gas pressure from the gas storage 34, so that the piston 40 is moved by its gas pressure. The piston 40 has a larger contact surface than the pistons 21 and 22 and presses the pistons 21 and 22 up to the other chamber wall, whereby the gas from the chamber 27 is pressed into the evaporator 17 until the chamber 27 is depressurized on this side , While one chamber 27 is being emptied, the other chamber 28 is filled with medium from the tank 1 when the shut-off elements 4 and 12 are open.

To move the piston 40, the pressure of the gas from the gas reservoir 34 opposite side of the cylinder 29 must be relieved of pressure. For this purpose, the pressure on this side of the cylinder 29 is reduced as a function of the substance data, with methane being reduced to preferably 100 bar. The chamber of the cylinder 29 to be relieved is therefore connected to the gas space of the tank 1 by opening the shut-off member 36, so that the gas drops to the predetermined pressure by throttling or an expansion machine in the connecting line 37. The pressure is established by an overflow upstream of the tank 1. Before the gas reaches the overflow, it flows through the heat exchanger 16 and is cooled there with the liquid of the tank 1 at the boiling temperature. The gas temperature drops below the critical temperature in the heat exchanger 16 and the gas condenses. Liquid is present at the overflow under very high pressure. The pressure is reduced by opening the overflow to the set pressure by releasing pressure into the tank, the throttling producing liquid and gas phase or only liquid. Liquefied gas and possibly some gas enters tank 1. The pressure does not rise since liquid previously flowed from the tank 1 into the chamber 28 and the liquid level was lowered.

The process described is now repeated by connecting the chamber 28, which has been filled with liquid medium from the tank 1, to the evaporator 17.

2 comprises a vacuum-insulated tank 41, in which cryogenic ver8 / 15

AT518 299 B1 2018-03-15 Austrian patent office for liquid gas, e.g. Methane or another cryogenic liquefied gas. The tank 41 is optionally connected to the chamber 45 or the chamber 46 of the cylinder 47 via a line 42 and shut-off devices 43 and 44. The cylinder 47 is thermally insulated, in particular vacuum insulated. The gas return 48 of the chamber 45 and the gas return 49 of the chamber 46 are each connected to the gas space of the tank 41 via a shut-off device 50 and 51, respectively. The inlet of the chamber 45 and the chamber 46 are each connected to an evaporator 56 via a shut-off device 52 or 53, a line 54 and a heat exchanger 55. The gas return 48 of the chamber 45 and the gas return 49 of the chamber 46 are each connected to the evaporator 56 via a shut-off device 57 or 58 and a line 59.

In the cylinder 47, a displacement piston 60 is slidably mounted. The piston 60 is connected by means of a rigid connection on the rod 61 to an actuating piston 62 which is displaceably guided in a cylinder 63. At its opposite ends, the cylinder 63 has inlets or outlets 64 and 65, via which pressure medium can be supplied on one side, while pressure relief is carried out on the other side. For the supply of pressure medium, the inlets and outlets 64 and 65 are connected to a pressure accumulator 68 via shut-off devices 66 and 67. To relieve pressure, the inlets and outlets 64 and 65 are connected via shut-off devices 69 and 70, a line 71 and the heat exchanger 55 to the overflow valve 72, where the gas relaxes to tank pressure (intermediate tank 73, which is connected to the tank 41) becomes.

A pressure accumulator 75 is connected to the evaporator 56 via a shut-off element 74, which is filled with the medium regasified in the evaporator 56 and can then be transported away. The pressure vessel 68 can also be fed by the evaporator 56 via a shut-off element 76.

The operation of the regasification system shown in Fig. 2 is now as follows. The liquefied gas flows from the vacuum-insulated tank 41 into the chamber 46 solely by the geodetic pressure.

For this purpose, the shut-off element 43 is opened and a connection to the gas space of the tank 41 is established by opening the shut-off element 51 (gas decrease). If the chamber 46 is filled and the gas that may be formed flows out of the chamber 46 into the tank 41, the chamber 46 is separated from the tank 41 by closing the shut-off elements 43 and 51. Now the connection to the evaporator 56 is established by opening the shut-off device 52. Here, too, there is a gas drop from the evaporator outlet via line 59 to gas drop 49 of the chamber 46 by opening the shut-off member 58, which creates a pressure equalization and enables the chamber 46 to be emptied quickly by the geodetic pressure.

Between chamber 46 and evaporator 56 is a heat exchanger 55 in a row intermediate store. The product flows through the geodetic pressure from the chamber 46 first into the heat exchanger 55 upstream of the evaporator 56. This is located below the chamber 46, but above the evaporator 56. Therefore, the liquid only flows into the heat exchanger 55 by the geodetic pressure and fills it , Excess product flows through this into the evaporator 56 underneath. There is a sudden evaporation, so that the product can continue to flow until the chamber 46 is emptied.

The same pressure is set in the chamber 46 as in the evaporator 56. In the running process, this must be a pressure in the supercritical range. The pistons 60 and 62 are located on the piston rod 61. It is assumed that the piston 60 is in the end position on one (right) side of the cylinder 47. The piston 60 is driven by the actuating piston 62. The piston 62 is acted upon by the gas pressure from the gas storage 68, so that the piston 62 is moved by its gas pressure. The piston 62 has a larger contact surface than the piston 60 and presses the piston 60 against the other wall of the cylinder 47, whereby the gas is pressed from the chamber 46 into the evaporator 56 until the chamber 46 is depressurized. While one chamber 46 is being emptied, the other chamber 45 is filled with medium from the tank 41 when the shut-off elements 44 and 50 are open.

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AT518 299 B1 2018-03-15 Austrian

Patent Office To move the piston 62, the side of the cylinder 63 opposite the pressurization by the gas from the gas reservoir 68 must be relieved of pressure. For this purpose, the pressure on this side of the cylinder 63 is reduced as a function of the substance data, with methane being reduced to preferably 100 bar. The pressure moves on an isobar that never reaches the vapor space of the gas. The chamber of the cylinder 63 to be relieved is therefore connected to the gas space of the tank 41 by opening the shut-off device 69 or 70 via the line 71, so that the gas drops to the predetermined pressure by throttling or an expansion machine in the connecting line. The pressure is established by an overflow valve 72 connected upstream of the tank 41. Before the gas reaches the overflow valve 72, it flows through the heat exchanger 55 and is cooled there with the liquid in the tank 41 at the boiling temperature. The gas temperature in the heat exchanger 55 drops below the critical temperature and the gas condenses. Liquid is present at the overflow 72 under very high pressure. The pressure is reduced by opening the overflow valve 72 to the set pressure by expansion into the tank 41, the throttling producing liquid and gas phase or only liquid. Liquefied gas and possibly some gas enters the tank 41. The pressure does not rise since liquid previously flowed from the tank 41 into the chamber 45 and the liquid level was lowered.

The process described is now repeated by connecting the chamber 45, which has been filled with liquid medium from the tank 41, to the evaporator 56.

Up to this point, the exemplary embodiment according to FIG. 2 essentially corresponds to the exemplary embodiment according to FIG. 1. On the basis of FIG. 2, it is now to be shown that the regasification method described above is part of a system for regulating and delivering the electrical output power as required regenerative energy operated energy converter can be used. For this purpose, an energy converter is provided as a wind power plant 77. The electricity generated by the wind turbine 77 is supplied to a device 78 which is capable of switching back and forth between different electricity sources or interconnecting them in order to supply an air liquefaction system or an air separator 79 with electricity. The system 79 now liquefies the ambient air, for example, the liquid product being stored in an atmospheric tank 80. From there, the liquid product reaches the low-pressure tank 41 via a pump 81.

In times of an excess supply of electricity, the electricity generated by the wind turbine 77 is used for the operation of the air liquefaction system 79. The energy stored in the liquid product can be recovered if necessary by regasifying the liquefied gas, which can be done with the method described above. The high pressure gas generated in this way is stored in the gas storage, e.g. stored in gas cylinders 75. As described below, the energy released by the regasification can be converted into electrical energy as follows:

- driving a pressure increasing device by means of the pressure of the regasified gas, - using the pressure increasing device to compress a liquid medium, for example water, and to press it into a turbine, where it is expanded, - driving one electrical generator using the turbine to receive electrical energy.

In the exemplary embodiment according to FIG. 2, the pressure increasing device comprises a pressure lock 82 which comprises a cylinder 83 on one side and a cylinder 84 with a smaller cross section on the other side. A piston 85, 86 is slidably guided in cylinder 83 and cylinder 84, the two pistons 85, 86 being rigidly coupled to one another. On the side with the larger piston diameter, the pressure lock is acted upon by the gas from the gas accumulator 75 by opening the shut-off element 87 or 88. The pressure relief on the opposite side of the cylinder 83 takes place via the shutoff 10/15

AT518 299 B1 2018-03-15 Austrian

Patent Office organ 89 and 90, the heat exchanger 91 and the overflow valve 92 to the tank pressure of the

Tanks 41 and 73, respectively.

The smaller side of the pressure lock 82, i.e. the chambers of the cylinder 84 are alternately filled with a liquid, preferably water. This water is pressed with the gas pressure into the turbine 94, which is coupled to a generator 95. The generator generates the electricity for the grid requirement. As the piston 86 moves in one direction, the liquid or water is pressed into the turbine 94 and water flows in on the rear of the piston. The gas pressure and consequently the pressure on the smaller piston 86 is provided by the piston 85 of the large cylinder 83. In order for this to move, the gas pressure on the other side of the piston is lowered, so that the differential pressure which is established defines the inlet pressure to the turbine 94.

The process is controlled by shut-off valves. Through the opening thereof, the respective cylinder chamber is advantageously filled with pressureless water, or the pressure gas-carrying side is lowered to a low pressure. The pressure should be to the left of the critical point in the TS diagram. The outflowing gas is passed into the heat exchanger 91, where it is cooled below the critical temperature, so that part of the gas condenses. In the overflow valve 92 the expansion to tank pressure takes place. The gas fraction describes the possible efficiency of the process.

With regard to process control, the energy storage process consists of two circuits that work completely independently of one another. One is the gas liquefaction process. In this, the volatile current of the wind turbine or a photovoltaic system in the condenser 79 is used entirely for gas liquefaction. The liquefied gas is the storage medium and is stored in appropriate tanks. If the power to be supplied to the network is required, liquid is removed from this storage and fed to the regasification so that the gas can be used to drive the electricity-generating turbine 94, coupled to the generator 95, and to supply the power network as required.

It is unlikely that the wind turbine / photovoltaic system will supply electricity that ensures the operation of the condenser 79 at the optimum point. If the condenser 79 does not work at the optimal operating point, the liquid yield is low, so that the efficiency that can be achieved under favorable conditions is not achieved. In order to avoid this condition, enough power can be generated on the turbine 95 of the network supply that current is branched off for the optimal operation of the condenser 79 (power connection 96) and, if necessary, the network is 100% supplied.

If the power requirement for the condenser 79 to be produced by the turbine 95 is less than the loss due to a poor efficiency of the condenser 79, the condenser 79 can be switched off or go into stand-by mode.

Example: The condenser 79 has a requirement of 100 units, the efficiency of the liquefaction is 80%. If the turbine 94 performs 100 units and the wind turbine 77 produces 10 units, the condenser will go into stand-by mode. If the wind turbine produces 30 units, a net 10 units are saved.

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AT518 299 B1 2018-03-15 Austrian patent office

Claims (10)

claims 1. Methods for regasifying cryogenic liquefied gas, such as Methane, in which a portion of the cryogenic liquefied gas in a tank is fed from the tank via a pressure lock to an evaporator, in which this portion evaporates, whereupon the vaporized gas quantity is filled into a high-pressure gas store, fed into a pipeline network or an energy converter for generating electrical energy is supplied, characterized in that the pressure lock comprises two chambers (27, 28) which are alternately filled with a partial amount of the cryogenic liquefied gas from the tank (1), the chamber (27; 28) filled with the partial amount after the respective filling process is separated from the tank (1) and connected to the evaporator (17), whereupon a pressure equalization between the evaporator (17) and the chamber (27; 28) connected to it is established, and that at least one displacement body (21 ; 22) is displaced in such a way that it is contained in the chamber (27; 28) under evaporator pressure A gas is at least partially displaced into the evaporator (17) and the other chamber (28; 27) is filled with a portion of the cryogenic liquefied gas from the tank (1). 2. The method according to claim 1, characterized in that the two chambers (27, 28) are alternately connected to the tank (1) and to the evaporator (17). 3. The method according to claim 1 or 2, characterized in that the partial amount of cryogenic liquefied gas from the tank (1) is filled under the geodetic pressure in the chamber (27,28). 4. The method according to claim 1, 2 or 3, characterized in that the gas is brought under the geodetic pressure from the chamber (27, 28) into the evaporator (17). 5. The method according to any one of claims 1 to 4, characterized in that the gas is transferred from the chamber (27, 28) into the evaporator (17) via a heat exchanger (16), in which heat is supplied to the liquefied gas. 6. The method according to any one of claims 1 to 5, characterized in that each chamber (27; 28) is assigned its own displacement body (21; 22), the displacement body (21; 22) for simultaneously displacing the gas from the one chamber (27; 28) in the evaporator (17) and filling the other (28; 27) chamber with cryogenic liquefied gas from the tank (1) can be moved synchronously. 7. The method according to any one of claims 1 to 6, characterized in that the displacement of the displacement body or bodies (21, 22) is carried out by applying gas pressure, in particular gas pressure from a high-pressure gas store (34) fed by the evaporator (17). 8. The method according to any one of claims 1 to 7, characterized in that an actuating piston (40) in an actuating cylinder (29) is displaceable and for synchronous movement with the displacement body (s) (21) (22) and the displacement of the displacement body (s) (21, 22) is carried out by acting on one side of the actuating piston (40) with gas pressure, after or while on the opposite side of the actuating piston (40) a pressure release has taken place or has taken place. 9. The method according to claim 8, characterized in that the pressure release takes place in that the gas located on the opposite side of the actuating piston (40) is preferably cooled to condensation and expanded by throttling and as a liquefied and gaseous gas the tank ( 1) is returned. 12/15 AT518 299 B1 2018-03-15 Austrian patent office 10. The method according to claim 9, characterized in that the gas is condensed via the heat exchanger (16) and cooled in heat exchange with the liquid from the chamber (27, 28) into the evaporator (17), the condensation in the heat exchanger (16) is preferably carried out at constant pressure and is cooled down to an isobar in the T, s diagram which is to the left of the critical point and outside the steam range.