DE102011000492A1 - Liquefied gas tank with a power supply device for electrical equipment and method for generating electricity of an electrical device - Google Patents

Abstract

The invention relates to a liquid gas tank (10) comprising a power supply device for at least one electrical device (20, 28). The invention is characterized in that the power supply device comprises at least one energy converter (16) which generates electrical energy using the temperature difference between the liquid gas tank (10) or the components (24) connected to it and the environment, and with the electrical device ( 20, 28) is connected.

Description

The invention relates to a power supply device for electrical devices on a liquid tank according to the preamble of claim 1 and a method for powering an electrical device according to the preamble of claim 9.

Liquefied gas tanks are used for storing liquefied gases such. As nitrogen, argon, oxygen, carbon dioxide or combustible gases. These tanks are thermally insulated from the environment, in particular by vacuum insulation. Typical operating parameters, for example for nitrogen, are 10 bar pressure and -168 ° C temperature. Liquefied gas tanks require in a known manner electrical devices, for example, to monitor the level or the temperature or the like. The measured value obtained can either be displayed locally or be transmitted remotely by means of a radio module to a corresponding administration point. For the operation of these electrical equipment, an energy supply is necessary. This is done by connecting the electrical device to a power grid or by replacing batteries or accumulators.

However, these methods have the disadvantage that, on the one hand, long electrical lines are necessary, since liquefied gas tanks are generally installed on a site in separate areas. The installation of a fixed power supply is correspondingly expensive. When using rechargeable batteries or batteries there is the possibility that the replacement can be forgotten or a high temperature sensitivity in batteries or accumulators is present and thus the functionality of the electrical equipment can not be granted.

It is an object of the invention to provide a liquefied gas tank with an independent power supply device for at least one electrical device which is attached to a liquefied gas tank. Furthermore, the object is that the power supply is designed such that it can supply the electrical devices reliably and permanently with electrical energy in a simple manner without the connection to a power grid.

The object is solved by the characterizing features of claim 1 in conjunction with its generic features.

The dependent claims form advantageous developments of the invention.

According to the invention, an energy generator is provided for supplying an electrical device to a liquefied gas tank, which generates energy by utilizing the temperature difference between the liquefied gas tank or the components connected thereto. For the purposes of the invention, the fluidically coupled to the liquid gas tank components, such as outlet and possibly connected heat exchanger, are seen as part of the liquid gas tank.

Since extremely low temperatures occur during the storage of liquefied gas, a very high temperature difference results from the gas tank to the environment, which is used to generate energy. This has the advantage that on-site resources due to the low temperature in the gas tank and the resulting temperature difference electrical energy can be generated, with the result that batteries or batteries do not need to be replaced or on the other hand no power lines are placed in remote locations for liquefied gas tanks and yet the benefits of electrical equipment in the LPG tank can be exploited.

In a particularly advantageous embodiment, the energy converter is designed as a thermoelectric generator, in particular as a Peltier generator. Peltier generators are a proven and effective way to convert temperature differences into electrical energy. Such thermoelectric generators are based on the "Seebeck" effect, which describes charge separation based on a temperature difference.

As with a corresponding thermoelectric generator can thus be easily and inexpensively generated energy in place of the liquefied gas tank.

As an alternative to a Peltier generator, a thermoelectric generator can also be designed as a Stirling generator, wherein the heated area is formed by the ambient temperature and the cooled area is cooled by the extremely low gas temperature. For this purpose, corresponding devices may be provided between the first and second tank wall. This embodiment has the advantage that the temperature difference can be used to generate energy as long as there is LPG in the tank.

In an advantageous embodiment, the liquid gas tank comprises an inner tank wall and an outer tank wall, wherein the inner tank wall is vacuum-insulated from the outer tank wall and / or can also be filled with a perlite insulating powder. In this embodiment, it proves to be advantageous thermally between the energy converter the inner tank wall and the environment to couple, since the inner tank wall has the greatest temperature difference to the environment and can provide accordingly for the highest power generation.

In a further advantageous embodiment, the coupling can take place via a suspension of the inner tank in the outer tank.

In an alternative embodiment, the thermal coupling of the energy converter via a separate heat conductor z. As a copper rod to be implemented by this is coupled at one end to the inner tank wall with its other side to the outer tank wall or the surrounding atmosphere.

In a further advantageous embodiment, the energy converter can be coupled to the withdrawal line of the tank. This type of coupling has the advantage that the extraction line is easily accessible and a cooling release in this area is essential anyway. This increases the efficiency of the system.

The coupling of the energy converter to the extraction line of the tank or the upstream heat exchanger has the disadvantage that although a high temperature difference to the environment occurs during the removal of the liquefied gas or the heat exchanger, but on the other hand at standstill of the heat exchanger or Discharge line to the ambient temperature level adapt, which prevents a thermoelectric power generation.

Surprisingly, however, it follows that during filling and removal of. Liquefied gas in the tank so much energy can be produced in this way and this can be cached in designated accumulators to ensure a power supply to the electrical equipment, and to bridge for longer downtime. Thus, in all phases of operation, a supply of electrical equipment by the energy converter in conjunction with connected accumulators can be ensured. No external energy needs to be supplied, making it unnecessary to replace energy storage units or connect to a power grid.

In an alternative embodiment, the energy generator may be thermally coupled to the outer tank wall. Especially at support points or on the suspensions of the inner tank still results in a permanent temperature difference between the suspensions and the environment. In this way, systemic cold bridges can be used to generate electrical energy to ensure the electrical power supply of electrical equipment.

As an electrical device according to the invention, among other actuators, such. As motor-operated relief valves, sensors in general such. As temperature sensors, pressure sensors or level sensors, understood. Also metrological evaluation and pressure transfer or memory modules are included.

In an advantageous embodiment, a controller and an energy store can be integrated into an electrical device to be supplied, whereas the thermal generator is connected via electrical lines to the electrical device. The components of the power supply device according to the invention can be distributed accordingly.

In order to reduce the energy consumed, moreover, it is proposed that the electrical device have a kind of sleep mode in which they are put into a standby state and are switched on only at certain intervals in order to carry out a measurement and then return it to standby mode become. This ensures significantly lower energy consumption and supports the supply system of a complete power supply.

Further proposed in the invention is a method for supplying energy to an electrical device to a liquefied gas tank by means of a power supply device, which is characterized in that an electric energy generator is used on a liquefied gas tank, which uses the temperature difference between LPG and environment for energy production. The temperature difference is preferably converted via a thermogenerator into electrical energy. This can then be supplied to an electrical energy store, which can be encompassed by the power supply device. From the power supply device, the electrical energy is transmitted to the electrical device, which is diverted either directly from the energy fed by the thermogenerator or from the existing energy storage.

Preferably, the electrical devices are turned off as soon as the LPG tank is empty. Since the electrical devices are used in particular for monitoring the LPG tank, and monitoring of an empty tank is not necessary, energy can be saved in this way. As soon as the liquefied gas tank is refilled, the electrical device is switched on again.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

In the description, the claims, and the drawing, the terms and associated reference numerals used in the list of reference numerals below are used. In the drawing:

1 a schematic view of a liquefied gas tank.

1 shows a liquefied gas tank 10 , which is executed in two-shell technique. On the one hand is schematically the inner tank wall 12 and the outer tank wall 14 shown. Between the tank walls 12 . 14 On the one hand there is a vacuum and on the other hand an insulating powder in the form of perlite. From liquefied gas tank 10 leads a withdrawal or supply line 24 via a heat exchanger 26 to a potential consumer. For monitoring parameters of the LPG tank is a measuring device 20 provided in the an energy storage 22 is integrated. The measuring device 20 is via lines with at least one thermogenerator 16 as well as at least one associated sensor 28 connected. For thermal coupling of the thermal generator 16 to the liquefied gas tank 10 and the environment there are a variety of possibilities, which are explained below by way of example.

In the schematic representation, for reasons of clarity, the thermogenerator 16 always shown outside the LPG tank, which also between the two tank walls 12 . 14 can be integrated, which does not support subsequent assembly.

In the schematic representation of 1 is each a thermogenerator 16 via connection points 30 . 32 . 34 . 36 . 38 . 40 . 42 with its cold side thermally to the gas tank 10 or coupled to a component connected thereto. The warm side represents the ambient air. It is also conceivable that a thermal coupling of several coupling points 30 . 32 . 34 . 36 . 38 . 40 . 42 on the thermogenerator 16 can be merged. Since this is not the preferred embodiment of the invention, this will not be explained in detail at this point.

In the following, the different, favored thermal coupling points are shown.

Schematically are different coupling points 30 . 32 . 34 . 36 . 38 . 40 . 42 shown which the cold side of the thermal generator 10 thermally with one with the liquefied gas tank 10 coupled component coupled.

For example, the thermogenerator 16 with a heat conductor at a contact point 42 to the inner tank 12 coupled or via a thermowell 34 in the outer tank wall 14 be introduced. As a result, it is brought closer to the inner container wall.

Another alternative embodiment is the coupling to a thermal conductor 40 the thermally insulated from the outer wall, however, projects into the free space of the insulation.

Another possibility is the coupling of the thermogenerator 16 on the outer skin 14 at a connection point 36 on which the suspensions or straps 18 of the inner liquefied gas tank 12 connected. These are inherently cold bridges and can therefore be used well for generating energy, especially since they are also very easily accessible from the outside.

Alternative embodiments also form the coupling to the removal or supply line 24 , preferably at the outlet of the removal or supply line 24 from the liquefied gas tank 10 , Also conceivable is a coupling via the coupling point 30 at the heat exchanger 26 ,

The thermal couplings can be combined in such a way that the heat coupling produced at the cold bridges is used all the time. In addition, when removing or filling, the at the sampling line 24 or at the heat exchanger 26 incurred temperature difference used for energy.

1 shows possibilities of thermal coupling of a thermogenerator 16 to a liquid tank 10 , The coupling points shown can be used individually or in any combination within the meaning of the invention.

By using the energy stored in the temperature difference, a self-sufficient power supply for electrical equipment on the liquefied gas tank can be ensured.

LIST OF REFERENCE NUMBERS

10

LPG tank

12

inner tank wall

14

outer tank wall

16

thermogenerator

18

suspension

20

measuring device

22

accumulator

24

Sampling supply line

26

heat exchangers

28

sensor

30

coupling point

32

coupling point

34

coupling point

36

coupling point

38

coupling point

40

coupling point

42

coupling point

Claims (11)

Liquefied gas tank ( 10 ) comprising a power supply device for at least one electrical device ( 20 . 28 ), characterized in that the power supply device at least one energy converter ( 16 ) taking advantage of the temperature difference between the liquid gas tank ( 10 ) or related components ( 24 ) and the environment generates electrical energy, and with the electrical device ( 20 . 28 ) connected is. Liquefied gas tank according to claim 1, characterized in that the energy converter based on the Seebeck effect, in particular as a Peltier generator ( 16 ) is trained. Liquefied gas tank ( 10 ) according to one of the preceding claims, characterized in that the liquefied gas tank ( 10 ) an inner tank wall ( 12 ) and an outer tank wall ( 14 ), wherein the energy converter ( 16 ) via a thermal coupling ( 42 . 36 ) to an inner tank wall ( 12 ) is coupled. Liquefied gas tank ( 10 ) according to one of the preceding claims, characterized in that the energy converter ( 16 ) to a sampling line ( 24 ) of the LPG tank ( 10 ) is coupled. Liquefied gas tank ( 10 ) according to one of the preceding claims, characterized in that the liquefied gas tank ( 10 ) an inner tank wall ( 12 ) and an outer tank wall ( 14 ), wherein the energy converter ( 16 ) thermally to the outer tank wall ( 14 ) is coupled. Liquefied gas tank ( 10 ) according to one of the preceding claims, characterized in that the liquefied gas tank ( 10 ) an inner tank wall ( 12 ) and an outer tank wall ( 14 ), wherein the energy converter ( 16 ) thermally to the suspension of the inner tank ( 14 ) is coupled. Liquefied gas tank ( 10 ) according to one of the preceding claims, characterized in that the power supply device comprises a current memory ( 22 ) associated with the energy converter ( 16 ) connected is. Liquefied gas tank ( 10 ) according to one of claims 6 to 8, characterized in that the power supply device comprises a control device which stores the current memory ( 22 ) during power generation of the energy converter ( 16 ). Method for supplying energy to an electrical device on a liquefied gas tank ( 10 ), characterized in that for generating energy at least one electric thermal generator ( 16 ) is used. A method according to claim 9, characterized in that by the thermogenerator ( 16 ), if energy is generated, an energy store ( 22 ) is charged, by which provided no more energy from the thermogenerator ( 16 ) is generated, the at least one electrical device ( 20 . 28 ) supplied with energy. Method according to one of claims 9 or 10, characterized in that the electrical device ( 20 . 28 ) is switched off when the LPG tank ( 10 ) is empty.

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