DE102018101946A1 - Generation of liquefied gas in a gas storage - Google Patents

Abstract

In particular, there is disclosed a method performed by one or more devices, the method comprising: reducing a pressure of natural gas stored in a gas reservoir, wherein after the reduction, the natural gas has a predetermined constant pressure; Cleaning of natural gas stored in a gas storage; and generation of liquefied gas based on the purified natural gas, wherein the generation of the liquefied gas in the context of the withdrawal of natural gas stored in the gas storage is carried out in a gas network connected to the gas storage. Furthermore, an apparatus and a system are disclosed.

Description

area

Exemplary embodiments of the invention relate to the generation of LPG in a gas storage.

background

In Europe, an increase in LPG is expected in the coming years. In the media, liquefied petroleum gas is traded as a bridge technology in decarbonization. Especially in long-distance transport, LPG is mentioned as a possible substitute for diesel fuel. If liquefied petroleum gas gains acceptance as an alternative fuel to diesel, for heavy-duty traffic or even for shipping (in particular inland shipping), a technical supply concept would be desirable.

Flexible supply of various customer groups (eg inland navigation, filling stations for heavy goods traffic, to name only a few non-limiting examples) with liquefied petroleum gas as fuel would be desirable, in particular falling gas volumes in gas networks and trade could be reduced.

The conventional production of LPG is very energy intensive. The main cost drivers are the operating costs. Due to the costs, liquefied petroleum gas has so far only been used as an energy source in selected niches.

Furthermore, it is known that cold arising in the storage of natural gas in a gas storage is cost-intensive and wasted unused.

It would be desirable to be able to provide a solution in order to be able to generate liquefied gas in a cost-optimized manner.

Summary of Some Exemplary Embodiments of the Invention Against the background of this prior art, it is an object of the present invention to provide a solution for generating liquefied gas as inexpensively as possible.

This object is achieved by a method having the features of claim 1.

• - Reduzierung eines Drucks von in einem Gasspeicher gespeicherten Erdgas, wobei nach der Reduzierung das Erdgas einen vorbestimmten konstanten Druck aufweist;
• - Reinigung von in dem Gasspeicher gespeicherten Erdgas; und
• - Erzeugung von Flüssiggas basierend auf dem gereinigten Erdgas, wobei die Erzeugung des Flüssiggases im Rahmen der Ausspeicherung von in dem Gasspeicher gespeicherten Erdgas in ein mit dem Gasspeicher verbundenes Gasnetz durchgeführt wird.

According to a first exemplary aspect of the invention, a method, in particular for producing liquefied gas, carried out by one or more devices is described, comprising the method:

• Reducing a pressure of natural gas stored in a gas reservoir, wherein after the reduction, the natural gas has a predetermined constant pressure;
• - Cleaning of stored natural gas in the gas storage; and
• - Generation of LPG based on the purified natural gas, wherein the generation of the liquefied gas is carried out in the context of the withdrawal of stored in the gas storage natural gas in a gas storage connected to the gas network.

It requires a differential pressure of about 55 bar to convert natural gas as a raw material into liquid gas through expansion. This differential pressure is already regularly as a difference of stored in the gas storage natural gas and a pipeline of a transport network to transport the natural gas z. B. to consumers available. In order to produce liquefied gas cost-optimized, therefore, the existing pressure difference in a gas storage is used.

The method according to the first aspect can be carried out in particular by a device (for example device for producing liquefied gas). The method according to the first aspect may also be used in particular by a plurality of devices, e.g. B. a device for the purification of natural gas and another device for generating LPG are performed together. The one or more devices are arranged to carry out and / or control the method according to the first aspect of the invention or comprise respective means for carrying out and / or controlling the steps of the method according to the first aspect of the invention.

In the case that the method according to the first aspect of the invention is performed by one or more devices (eg, apparatus for purifying natural gas and another apparatus for producing liquefied gas) together, the respective apparatuses may respectively have respective means for execution and / or control of the respective steps performed by the corresponding device (eg device for purifying natural gas or another device for producing liquefied gas). For example, not all steps of the method according to the first aspect of the invention are performed by one of the devices.

According to a second exemplary aspect of the invention, there is disclosed an apparatus arranged to carry out and / or control the method according to the first aspect of the invention, or respective means for execution and / or Controlling the steps of the method according to the first aspect of the invention. In this case, either all steps of the method can be controlled, or all steps of the method can be executed, or one or more steps can be controlled and one or more steps can be executed. One or more of the means may also be executed and / or controlled by the same unit. For example, one or more of the means may be formed by one or more processors.

According to a third exemplary aspect of the invention, a system is disclosed which comprises one or more devices arranged to carry out and / or control the method according to the first aspect of the invention or means for carrying out and / or controlling the steps of the method according to the first aspect of the invention. In this case, either all steps of the method can be controlled, or all steps of the method can be executed, or one or more steps can be controlled and one or more steps can be executed.

These three aspects of the present invention have u. a. the below described - partly exemplary - properties.

The term "expansion" is understood to mean in particular a relaxation of natural gas, wherein after the expansion of the natural gas is at least under lower pressure than before expansion.

The term "liquefied gas" is understood in particular liquefied natural gas, also referred to as liquid natural gas (LNG). In particular, this does not include the so-called Liquified Petroleum Gas (LPG), which is often used for example by cars z. B. is usable by a corresponding conversion of the vehicle as a fuel.

A "gas storage" is understood to mean a natural gas storage. Such natural gas storage are in particular large, mostly underground storage facilities, with which, for example, seasonal fluctuations in demand by a storage of previously stored in the memory natural gas is possible.

The gas network is for example a transport network in which natural gas with a predefined pressure of z. B. is transported about 30 bar.

In a gas storage, in particular, there is a sufficient pressure difference (differential pressure Δp, also referred to as delta p) between the natural gas stored in the gas storage and the gas network into which stored natural gas can be stored from the gas storage to produce liquefied gas (LNG) to perform in such gas storage in the context of the withdrawal.

It is thus possible to produce liquefied petroleum gas by gas expansion in a gas reservoir. Generated liquid gas can also be stored at least temporarily.

The amount of energy that was used to increase the pressure prior to the storage of natural gas in the gas storage (eg., Formed as a cavern underground storage), is at a withdrawal of the gas z. As in the gas network (eg., Transport network) not entirely lost, since in carrying out the method according to the first aspect of the invention, this amount of energy, for the production of liquefied natural gas (LNG) is used or used.

The generation of liquefied gas, in particular by an expansion of natural gas, which is stored in a gas storage, is based on the finding that the pressure difference, z. B. in caverns large gas storage or in the outsourcing to the transport network for the production of liquefied natural gas is available. A gas storage with, for example, two caverns with different pressures (eg 50 bar and 200 bar) or a cavern or storage in the pore rock (eg 200 bar) with a connection to the natural gas transport network (eg 30-50 bar) can be used for example objectively. During expansion (i.e., expansion) from one cavern to the other, or into the natural gas transport network, the Joule-Thompson effect can be used to generate cold and thus reduce the temperature of the natural gas. This resulting expansion energy is at least partially used in the relocation or outsourcing of natural gas to produce liquefied petroleum gas (LNG). Since such a rearrangement and / or expansion is carried out in the transport network in the regular operation of the gas storage, consequently, the liquefied gas can be generated in particular inexpensively.

The pressure reduction takes place in order to have a so-called constant system in the context of the production of liquefied gas, so that always with the one or more devices, the process in which as a result LPG is produced, can be performed. The pressure reduction may be necessary, for example, because the prevailing pressure in the gas storage (eg cavern pressure) changes over the course of the year. This can be done for example by external and naturally conditioned environmental influences. In particular, gas reservoirs designed as cavern storage are subject to such pressure fluctuations. The pressure reduction can, for example, by means of a pressure control valve, an expander, or a vortex tube to give just a few non-limiting examples. The purification of the natural gas may include a drying of the natural gas. Such drying of the natural gas changes the natural gas such that sometimes water taken from the natural gas is taken out of the natural gas. The cleaning and drying of the natural gas can take place, for example, in a single step. Alternatively, the purification and drying of the natural gas may each be separate steps of the method according to the first aspect of the invention. Accordingly, the purification and drying of the natural gas may be performed by a single device, or alternatively by two separate devices. For example, in the case where the purification and the drying of the natural gas are performed as steps separately from each other, the order of the steps may be changed. Accordingly, for example, the first purification of the natural gas, and then its drying. Alternatively, for example, first the drying of the natural gas take place, and then its purification.

The cleaning and / or drying of the natural gas stored in the gas storage comprises or is carried out, for example, by equipment comprising components such. As water and carbon dioxide, which complicate the production of liquefied gas, extract the natural gas. This enables a stable subsequent generation of the liquefied gas.

• - Kühlen des gereinigten Erdgases vor der Erzeugung des Flüssiggases, wobei das Kühlen des gereinigten Erdgases mittels eines ersten Wärmetauschers erfolgt und dabei kondensiert, und wobei ein erster Teil des gekühlten Erdgases an einen zweiten Wärmetauscher geleitet wird und durch Unterkühlung und Expansion Flüssiggas erzeugt wird; und wobei das Kühlen des Erdgases durch eine Expansion mittels eines Differenzdrucks, der bei einem Einspeichern des in dem Gasspeicher gespeicherten Erdgases aufgebracht wird, erfolgt.

According to another embodiment in all aspects, the method further comprises:

• - cooling the purified natural gas prior to the generation of the liquefied gas, wherein the cooling of the purified natural gas takes place by means of a first heat exchanger and condenses, and wherein a first portion of the cooled natural gas is passed to a second heat exchanger and is generated by subcooling and expansion of liquid gas; and wherein the cooling of the natural gas is carried out by an expansion by means of a differential pressure, which is applied when storing the natural gas stored in the gas storage.

The cooling is done for example by means of a pre-cooling and natural gas expansion. To generate the liquefied gas, a differential pressure of at least 50 to 55, 51 to 54, 52 to 53, preferably at least 55 bar is required in order to be able to produce liquefied gas in a cost-effective manner using this process according to the first aspect of the invention. This differential pressure can be found in underground storage - as stated above.

The generation of the liquefied gas takes place, for example, such that no negative influence on the usual storage operation takes place.

Apart from the footprint for the device or devices to be retrofitted (eg installations and / or components), in contrast to conventional liquid gas production, no further landscape consumption takes place.

With the generation of liquid gas in the gas storage (eg underground storage) an existing gas storage can take on new tasks in the liquefied gas generation in addition to its previous tasks in the gas network.

The expansion by which the liquefied gas is generated is, for example, such that the natural gas after the expansion is cooled so as to change in its state of aggregation and accordingly change from a gaseous state to a liquid state. This aggregate state change, which is necessary for the production of the liquefied gas, takes place approximately at a temperature of -160.degree. The cooling of the natural gas to achieve this temperature takes place at least partially by means of the expansion. It is envisaged that this differential pressure already arises during the storage of natural gas in the gas storage. By shifting the production of the liquefied gas into a process of the withdrawal of natural gas from the gas storage, the energy already used to compressed natural gas at a pressure increased in the gas storage compared to the gas network (ie reduced in volume) can be used to generate liquefied gas be used. This energy would otherwise be destroyed in an ordinary withdrawal of natural gas from the gas storage by the expansion of the natural gas to equalize the pressure that the natural gas has in the gas storage, to the pressure of the gas network, unused.

An embodiment according to all aspects provides that the generation of the liquefied gas is carried out substantially simultaneously to a withdrawal of natural gas stored in the gas storage.

The production of the liquefied gas takes place, for example, based on stored in the gas storage natural gas, which is to be stored, for example, to compensate for fluctuations in consumption in the gas network in the gas network.

The ordinary operation of the gas storage used to generate the liquefied gas is consequently not disturbed.

A further embodiment according to all aspects provides that wherein the liquefied gas is generated after passing through at least two heat exchangers, wherein in particular a Joule-Thompson expansion of the natural gas is carried out.

In particular, the liquefied gas is generated by a total of two heat exchangers.

In the Joule-Thompson expansion, a temperature change of the natural gas used to produce LPG occurs at a pressure reduction. As a result, when falling below a predetermined temperature (about -160 ° C), the natural gas is liquefied, whereby the liquefied gas (LNG) is generated.

In one embodiment according to all aspects, the liquid gas produced is stored at least temporarily in a liquid gas storage.

Generated liquefied gas can in particular be stored at least temporarily. After this temporary storage Boil-off gas (BOG) arising at least during storage must be removed from the storage. The BOG can be used to refuel CNG (compressed natural gas) vehicles or fed back into the gas grid. Accordingly, produced liquefied gas should be continuously consumed, since during storage just this boil-off gas is produced.

In a further embodiment according to all aspects required for the production of the liquefied gas is generated at least partially based on that natural gas, which is to be stored on the one hand, and on the other hand to be generated from the liquefied gas.

Accordingly, needed refrigeration is also obtained, at least in part, also based on the natural gas that is to be stored on the one hand, and on the other hand is to be generated from the liquefied gas (by a corresponding conversion of at least a portion of the second part of the cooled natural gas).

Accordingly, the energy required for the generation, which is needed especially for cooling the natural gas, so that the natural gas changes its state of aggregation from gaseous to liquid, whereby liquefied gas is generated.

An embodiment according to all aspects provides that the first part of the cooled natural gas can be ausspeicherbar after reducing the pressure in a gas network. The pressure reduction ensures in particular that cold arises. This cold is used, for example, to generate liquefied gas. A pressure reduction is also required in order to be able to store natural gas, which is stored in the gas storage, in a pipeline of the gas network. The stored natural gas in the gas storage is brought, for example, by the pressure reduction to the pressure present in a gas network into which the natural gas is to be stored.

In one embodiment, in all aspects, the storage of the generated liquefied gas causes leakage (eg, escape) of a quantity of natural gas, wherein the amount of natural gas exiting the liquefied gas storage by heating the stored liquefied gas is usable for further use.

During the storage of liquefied gas, the temperature of the stored liquefied gas increases. This increase in temperature of the stored liquefied gas leads to the escape of at least part of the stored liquefied gas, which is also referred to as boil-off gas (BOG).

Instead of leaving this boil-off gas unused, for example by the boil-off gas fizzling, this can be used, for example, for further use.

For example, this amount of natural gas escaping (or vaporizing) from a reservoir in which the generated LPG is stored may be subject to further use. For example, after a pressure adjustment that is sometimes required (for example due to compression), this evaporated natural gas can be stored out into the gas network. In this case, natural gas evaporated from a liquid gas reservoir generally has a lower pressure than the pressure which prevails in the gas network connected to the gas storage, which comprises the liquid gas reservoir. Accordingly, a compression of the natural gas may be necessary to be able to store this natural gas in the gas network can.

Accordingly, a further embodiment according to all aspects, that the amount of natural gas for further use a third heat exchanger for heating natural gas is supplied (or is supplied).

The third heat exchanger heats, for example, natural gas before a storage of the stored natural gas in the gas storage in the gas network or in a pipeline of the gas network. Accordingly, the third heat exchanger, for example, z. B. connected via an interface with the gas network or the pipeline of the gas network.

An embodiment according to all aspects provides that a quantity of liquefied gas can be used as fuel for further use.

For this purpose, for example, the amount of liquid gas in a corresponding (eg mobile) memory, for. For example, be stored in the manner of a tank, so that the amount of gasified LPG from this mobile tank as a fuel to be supplied to a motor can be fed. This amount may be used, for example, for vehicles (eg, trucks, locomotives, ships, to name just a few non-limiting examples).

For example, the boil-off gas may also be used as fuel for traffic.

In one embodiment according to all aspects of the gas storage is an underground gas storage.

Gas storage are u. a. Underground storage, also referred to as Underground Gas Storage (UGS), where natural gas can be stored in natural or artificial cavities beneath the surface of the earth by means of such underground storage. Such gas storage are, for example, aquifer and pore storage, cavern storage or tube storage. Tubular storage systems are medium sized natural gas storage tanks to compensate for fluctuations in demand. Tube stores are used, for example, to cover daily demand peaks, as they have high output and feed-in capacities.

In the underground storage, there is sufficient pressure difference (between the natural gas stored in the underground storage and the gas network into which stored natural gas can be stored from the underground storage) to carry out generation of liquefied natural gas (LNG) in such gas storages can.

In a further embodiment according to all aspects, the one or more devices are included in the gas storage or part of the gas storage.

The one or more devices that perform and / or control the method according to the first aspect are in particular in the immediate vicinity of the gas storage, or are even within the gas storage, which is formed in this case, in particular as underground storage. The one or more devices are arranged, for example, between the interface via which the gas storage can store stored natural gas (for example into a pipeline) and the interface via which natural gas stored in the gas storage can be stored out of the storage , Further details can be found in the section "Detailed description of some exemplary embodiments of the invention".

A further embodiment according to all aspects provides that the cooling is performed at least partially by cooling the natural gas by a refrigeration system.

In an embodiment according to all aspects, the first part of the cooled natural gas is subject to a pressure increase by means of a compressor.

In the event that an amount of natural gas on which at least partially based on the production of the liquefied gas is carried out, for the withdrawal from the gas storage in the gas storage is too low pressure, by means of the compressor, the pressure of the natural gas can be increased. Too low a pressure may, for example, arise because during the evaporation of the liquefied gas, in which the natural gas is heated (in its temperature is increased by the storage), too much expanded. This may be the case, for example, if the cold needed to produce the liquefied gas for cooling the natural gas could not yet be completely generated by expansion of the natural gas. Accordingly, in this case, a further expansion of the natural gas take place in order to generate this required refrigeration for the production of the liquefied gas.

In a further embodiment, in all aspects, a fourth heat exchanger heats the first portion of the cooled natural gas for compression by the compressor and / or for withdrawal from the first portion of the cooled natural gas into the gas network.

In particular, the pressure of the natural gas to the gas network or to a connected to the gas storage pipeline, in which the natural gas is stored, for example, by means of the fourth heat exchanger, the temperature of the natural gas auszuspeichernden be increased. This also indirectly causes a change in the pressure under which the natural gas is, so that is adjusted accordingly in the sequence by the heating of the pressure of auszuspeichernden natural gas to that pressure of the gas network or the pipeline or is.

In one embodiment according to the third aspect of the invention, the one or more devices together execute and / or control an objective method according to the first aspect of the invention.

In a further embodiment according to the third aspect of the invention, the one or more devices according to the second aspect of the invention are formed.

In an exemplary embodiment according to the third aspect, the system comprises at least a natural gas storage facility, and at least one apparatus for producing liquefied petroleum gas, wherein the at least one apparatus for generating liquefied gas is adapted thereto or comprises corresponding means for carrying out and / or controlling a method according to the first aspect of the invention.

The one device is for example a single device. Alternatively, the method according to the first aspect of the invention is performed and / or controlled by a plurality of devices (i.e., at least two devices, e.g., each formed as plant parts). For example, one of the plurality of devices is configured and / or includes such means to perform a natural gas purification (eg, natural gas purification system), and another device of the plurality of devices is configured and / or includes such means to facilitate liquefied gas production (e.g. B. a liquefied gas generating plant).

• i) Einen oder mehrere Wärmetauscher;
• ii) Einen oder mehrere Druckminderer;
• iii) Einen oder mehrere Druckerhöher (z. B. Kompressor, oder ein Druckerhöher mit Kühler);
• iv) Eine oder mehrere Kälteanlagen;
• v) Eine oder mehrere Speicher zur Speicherung (z. B. Lagerung) von erzeugtem Flüssiggas;
• vi) Eine oder mehrere Schnittstelle zur Ausspeicherung von während der Erzeugung des Flüssiggases verwendetem Erdgas in ein Gasnetz (z. B. Verteilnetz, und/oder Transportnetz);
• vii) Einen oder mehrere Reinigungsanlagen; und
• viii) eine oder mehrere Trocknungsanlagen

The apparatus for producing liquefied gas may comprise, for example, one or more of the following components i) to viii):

• i) one or more heat exchangers;
• ii) one or more pressure reducers;
• iii) one or more booster units (eg compressor, or a booster with radiator);
• iv) one or more refrigeration systems;
• v) one or more stores for storage (eg storage) of generated liquefied gas;
• (vi) one or more interfaces for the withdrawal of natural gas used during the production of the liquefied gas into a gas network (eg distribution network and / or transport network);
• vii) one or more cleaning installations; and
• viii) one or more drying plants

A possible, fundamental structure of a device for producing liquefied gas in a gas storage (for example underground storage) can be designed, for example, as follows:

• - Eine erste Druckreduzierung ist zu errichten oder eine vorhandene zu nutzen
• - Eine Erdgasreinigungs- und eine optionale Trocknungsanlage, die z. B. von der Erdgasreinigungsanlage umfasst ist,] ist zu errichten;
• - Eine Verflüssigungsanlage ist zu errichten;
• - Ein Behälter für die Lagerung von LNG ist aufzustellen;
• - Eine Abfüllanlage ist aufzubauen (der Einsatz einer mobilen LNG Tankstelle und/ oder CNG-Tankstelle ist optional möglich); und
• - Schließlich sind Verrohrungen und Steuerung, auch der bestehenden Komponenten anzupassen.

To z. For example, in order to fully recover the underground storage for the production of LPG, the following equipment and components should be installed:

• - A first pressure reduction is to be built or to use an existing one
• - A natural gas cleaning and an optional drying plant, the z. B. of the natural gas purification plant is included,] is to be erected;
• - A liquefaction plant is to be built;
• - A container for the storage of LNG must be set up;
• - A bottling plant is to be set up (the use of a mobile LNG filling station and / or CNG filling station is optional); and
• - Finally, piping and control, including the existing components to adapt.

Accordingly, for example, today's underground storage already have at least part of the necessary infrastructure.

The exemplary embodiments described above in this description are to be understood as disclosed in all combinations with each other. In particular, exemplary embodiments are to be understood in terms of the different aspects disclosed.

In particular, the preceding or following description of method steps according to preferred embodiments of a method also discloses corresponding means for carrying out the method steps by preferred embodiments of a device. Likewise, by the disclosure of means of a device for carrying out a method step, the corresponding method step should also be disclosed.

Further advantageous exemplary embodiments can be taken from the following detailed description of some exemplary embodiments, in particular in conjunction with the figures. However, the figures should only serve the purpose of clarification, but not to determine the scope. The figures are not to scale and are merely intended to exemplify the general concept. In particular, features included in the figures are by no means considered necessary components.

list of figures

• 1 eine schematische Darstellung eines Ausführungsbeispiels eines Systems gemäß der Erfindung;
• 2a, b jeweils eine schematische Darstellung eines ersten Teils des gemäß 6 gezeigten Ausführungsbeispiels eines Systems gemäß der Erfindung;
• 3 eine schematische Darstellung eines zweiten Teils des gemäß 6 gezeigten Ausführungsbeispiels eines Systems gemäß der Erfindung, welches basierend auf dem in 2 gezeigten Teils erweitert wurde;
• 4 eine schematische Darstellung eines dritten Teils des gemäß 6 gezeigten Ausführungsbeispiels eines Systems gemäß der Erfindung, welches basierend auf dem in 3 gezeigten Teils erweitert wurde;
• 5 eine schematische Darstellung eines vierten Teils des gemäß 6 gezeigten Ausführungsbeispiels eines Systems gemäß der Erfindung, welches basierend auf dem in 4 gezeigten Teils erweitert wurde;
• 6 eine schematische Darstellung eines weiteren Ausführungsbeispiels eines Systems gemäß der Erfindung; und
• 7 ein Flussdiagramm eines Ausführungsbeispiels eines Verfahrens gemäß der Erfindung.

In the drawing shows

• 1 a schematic representation of an embodiment of a system according to the invention;
• 2a, b in each case a schematic representation of a first part of according to 6 shown embodiment of a system according to the invention;
• 3 a schematic representation of a second part of according to 6 shown embodiment of a system according to the invention, which is based on the in 2 extended part was expanded;
• 4 a schematic representation of a third part of according to 6 shown embodiment of a system according to the invention, which is based on the in 3 extended part was expanded;
• 5 a schematic representation of a fourth part of according to 6 shown embodiment of a system according to the invention, which is based on the in 4 extended part was expanded;
• 6 a schematic representation of another embodiment of a system according to the invention; and
• 7 a flowchart of an embodiment of a method according to the invention.

Detailed Description of Some Exemplary Embodiments of the Invention

1 shows a schematic representation of an embodiment of a system according to the invention.

The system 100 includes a gas storage 110 , a device for natural gas purification 120 , a device for generating LPG 130 , and an optional device for storage of the generated liquefied gas 140 ,

The of the system 100 included devices 120 and 130 are in particular each devices according to the second aspect of the present invention.

In exemplary embodiments of the invention, natural gas is from the gas storage 110 popped. The natural gas to be evacuated is from natural gas purification 120 cleaned. On the basis of the purified natural gas is then from the device 130 Liquefied gas is generated, wherein the purified natural gas is cooled by supplying cold (cooling of the purified natural gas), whereby the purified natural gas changes the state of matter from gaseous to liquid, whereby liquefied gas (LNG) is generated. Subsequently, the liquid gas produced can optionally be stored or stored in a corresponding liquid gas storage. Natural gas, which was not used to produce LPG, can be put into a gas network (in 1 not shown), with the gas storage 110 connected, be stored out. Alternatively, the natural gas that is not used to generate LPG may be re-introduced into the gas storage 110 be stored. For this purpose, it may be necessary for the natural gas to be stored in the gas storage 110 must be compressed.

6 shows a schematic representation of another embodiment of a system according to the invention.

The system 600 includes - analogous to the system 100 according to 1 - a gas storage 610 (In the present case a underground storage, which is designed as a cavern with a pressure of about 85 to 200 bar), a device for natural gas purification and natural gas drying 620 , as well as a device for generating LPG 630 , The system 600 further comprises a device for preheating natural gas and reducing pressure 615 , a store 640 for storage or storage of the liquefied gas produced, as well as a connection to a pipeline 650 a gas network (eg a transport network). Before the withdrawal of natural gas into the pipeline 650 Optionally, a natural gas measurement from a corresponding device for measuring natural gas 660 be performed.

The device for generating LPG is so from the gas storage 610 includes, in particular in the context of the withdrawal of in the gas storage 610 stored natural gas, a generation of liquefied gas is feasible. For this, the present differential pressure between that in the gas storage 610 stored natural gas and the required pressure of the natural gas for the withdrawal into the gas network or in the pipeline 650 used the gas network to supply the natural gas via an expansion of natural gas, so that in the sequence of liquefied natural gas (LNG) is generated.

The device 630 for the production of liquefied gas in the present case comprises five heat exchangers 630-1 to 630-5 , a first Joule-Thompson expansion 630-8 , a second Joule-Thompson expansion 630-9 , a third Joule-Thompson expansion 630 -10, a refrigeration system 630-6 , as well as a compressor 630-7 ,

The device for preheating 615 includes a heat exchanger by means of the gas storage 610 taken natural gas is preheated. After preheating, a first Joule-Thompson expansion, wherein the natural gas is reduced in pressure, z. B. from 200 bar in the stored state in the gas storage 610 to about 85 bar after performing the Joule-Thompson expansion.

Subsequently, the natural gas in the device 620 to be cleaned for natural gas purification.

• - Erdgasreinigung/Erdgastrocknung u. a. Wasserstoff und Kohlendioxid werden adsorbiert,

In the context of natural gas purification, the following is carried out in the present case:

• - Natural gas purification / natural gas drying, etc. Hydrogen and carbon dioxide are adsorbed,

After natural gas cleaning and natural gas drying 620 there is a division of the natural gas (or the volume or mass flow of natural gas), wherein a first part of the natural gas to a heat exchanger 630-2 and a second portion of the natural gas to a heat exchanger 630-1 be directed. In the present case, a larger proportion of the mass flow (eg 75%) of the natural gas is used as the first part (to the heat exchanger 630-2 ), and smaller portion (eg, 25%) as the second part (to the heat exchanger 630 -1) split. The second part of the natural gas is by means of the heat exchanger 630-1 cooled, wherein the natural gas condenses after cooling a temperature. The of the heat exchanger 630-1 cold used to cool the second portion of the split natural gas is based at least in part on the first portion of the split natural gas.

The first part of the divided natural gas is by means of the heat exchanger 630-2 and 630-4 pre-cooled. The part of the natural gas from which the energy for cooling by the heat exchanger 630-2 or. 630-4 can be related to the natural gas measurement 660 for example, in the pipeline 650 be guided, as by necessary in the cooling energy by an expansion of the in the heat exchanger 630-2 , such as 630-4 derived natural gas is obtained. The expansion means that the natural gas, for example, has a pressure of about 30 bar, so that it can be fed into the pipeline.

In the 6 is also the system 600 continuous mass flow indicated m, the first by a pressure flow control 615-3 is produced. As a result, there is a mass flow m at a constant pressure.

Thereafter, the mass flow m passes through the natural gas purification plant 620 , which also performs a natural gas drying in the present case.

This mass flow m is divided into the mass flows m1 (about 25% of the total mass flow m) and m2 (about 75% of the total mass flow m). The mass flow m2 serves as the first cooling for m1. The mass flow m2 is through the heat exchangers 630-2 and 630-4 pre-cooled and brought to a low temperature by a refrigeration system. By the subsequent natural gas expansion 630-9 is the cooled natural gas for cooling the mass flow m1 in the heat exchanger 630-1 used. Thereafter, the mass flow m2 continues through the heat exchanger 630-2 heated and led to gas purification, as a regeneration in the natural gas purification plant 620 to serve. From there, the mass flow m2 becomes the gas network 650 about a natural gas measurement 660 comprises, supplied.

The in the heat exchanger 630-1 cooled mass flow m1 condenses and divides into the mass flows m3 (about 15% of the total mass flow m) and m4 (about 10% of the total mass flow m). The mass flow m4 is further cooled down by expansion 630 -10 and serves for the second cooling of the mass flow m3.

The mass flow m4 is after heating in the heat exchanger 630-3 the BOG mixed and over the heat exchanger 630-4 heated and brought by means of a compressor to the required pipeline pressure. From there, the mass flow m4 becomes the gas network 650 fed via a natural gas measurement.

The mass flow m3 is after cooling in the heat exchanger 630-3 through the expansion 630-8 cooled to the required liquefied natural gas (LNG) temperature and then stored. The LNG can z. For example, for LNG refueling, the BOG be used for CNG refueling.

After passing through the heat exchanger 630-4 becomes that part of the natural gas by means of the refrigeration system 630-6 , which obtains its energy for cooling, for example, from an external energy source (eg propylene), further cooled. This is in the present case by means of the heat exchanger 630-5 that with the refrigeration system 630-6 connected, performed. This so cooled natural gas is after an expansion in the heat exchanger 630-1 initiated, whereby, as already stated above, the second part of the divided natural gas can be cooled.

In order to achieve the required temperature of about -160 ° C for the production of liquefied natural gas (LNG) by cooling the natural gas, a Joule-Thompson expansion takes place 630 -10 based on another part of the natural gas, which is the heat exchanger 630-1 has already gone through. The through this Joule-Thompson expansion 630 -10 energy is generated by the heat exchanger 630-3 used that in the heat exchanger 630-3 initiated natural gas continues to cool. After passing through the heat exchanger 630-3 As a rule, the natural gas does not quite have the temperature necessary for the production of liquefied natural gas (LNG), so that a further Joule-Thompson expansion 630-8 of the natural gas reduces this in temperature so that subsequently liquefied gas is generated. This generated LPG can be used for example in the liquefied gas storage 640 get saved.

During the storage or storage of the produced liquefied gas in the liquefied gas storage 640 arises boil-off gas, in 6 denoted by the abbreviation BOG. Again 6 can be seen, this BOG can continue to be used, in this case, this example, after a run of the compressor 630 -7 in the pipeline 650 the gas network are initiated or fed.

• - Nach der Erzeugung des Flüssiggases, wird das erzeugte Flüssiggas (LNG) gelagert. Diese Lagerung kann beispielsweise derart erfolgen, dass ein LKW bzw. ein entsprechend ausgebildeter und von dem LKW transportierter Behälter als Speicher genutzt wird. Derart kann das erzeugte Flüssiggas (LNG) transportiert werden, z. B. zur weiteren Verwendung. Der zum Transport verwendete Behälter muss dicht und isoliert sein. Der Behälter ist beispielsweise ein passiver Behälter, der also insbesondere keine aktive Kühlung des gespeicherten Flüssiggases durchführt. Dies ermöglicht insbesondere eine flexible Versorgung von diversen Kundengruppen.

In the context of the production of the liquefied gas, the following is carried out in the present case:

• After the generation of the liquefied gas, the produced liquefied gas (LNG) is stored. This storage can for example be such that a truck or a suitably trained and transported by the truck container is used as storage. In this way, the produced liquefied gas (LNG) can be transported, e.g. B. for further use. The container used for transport must be tight and insulated. The container is, for example, a passive container, which therefore in particular does not carry out active cooling of the stored liquid gas. This enables in particular a flexible supply of various customer groups.

In particular, refrigeration is required for the production of liquefied gas (LNG production), for example, about 85% of the natural gas, on the basis of which the production of the liquefied gas is carried out, is used for the refrigeration production. The remaining approximately 15% (25% divided into 10% and 15%) of the natural gas are converted into liquefied petroleum gas. It is advantageous, in particular, that the quantities of natural gas used for refrigeration (for example, about 85%) are not lost but can continue to be used, since they are stored out into the gas network, for example after refrigeration. From there, the natural gas, for example, again in the gas storage, was originally stored by the natural gas used to produce the liquefied gas, are stored.

The prevailing temperatures and pressures of the natural gas, which this each after passing through a device covered by the system ( 610 to 660 ) 6 in each case by an appropriate indication, which at the respective device in 6 is shown, are taken. These indications of temperatures and pressures should also be understood as being disclosed in connection with all aspects of the present invention.

The in the 2a to 5 used reference numerals correspond to those in the 6 used reference numerals. It is understood that this is not limiting to the subject matter. All of the in the 2a to 5 shown and of the respective systems according to the 2a to 5 used entities (eg preheating 615 , Natural gas cleaning and drying 620 , Liquefied gas production 630 ) can each with each other according to the 2a to 5 as well as of the entities of 6 be independent. The in the 2a to 6 For example, entities represented schematically may be the same, and accordingly not the same.

2a shows a schematic representation of a first part of the according to 6 shown embodiment of a system according to the invention. 2 B shows the according to 2a represented part of the system, with respect to 2a arranged after the pressure reduction, a heat exchanger which uses at least a portion of the gas before the pressure reduction for the corresponding heat exchange.

In Ausspeicherstrand two pressure reductions are provided. The first one serves to generate a constant mass flow. After natural gas cleaning and drying, the second pressure reduction takes place, during which the expansion (expansion) causes cold.

Across from 2a is in 2 B a second mass flow is present, which is discharged after the purification and cooled by a heat exchanger and condenses.

3 shows a schematic representation of a second part of the according to 6 shown embodiment of a system according to the invention, which is based on the in 2 shown part was extended.

The condensed mass flow is after cooling and condensation (see. 2 B) again divided, wherein the derived mass flow is further cooled by a third pressure reduction.

This creates again cold, which is exchanged via a heat exchanger, which is to produce the liquefied gas (LNG). Thereafter, the mass flow is passed through a further heat exchanger, which serves as a pre-cooling for the mass flow in the Ausspeicherstrang. Via a compressor, this mass flow is brought back to pipeline pressure.

4 shows a schematic representation of a third part of the according to 6 shown embodiment of a system according to the invention, which is based on the in 3 shown part was extended.

The mass flow condensed through the second mass flow is then expanded by a fourth pressure reduction. The resulting cold of - 160 ° C is reached and LPG (LNG) can then be stored.

The BOG can z. B. are used for CNG refueling or re-stored in the gas storage.

5 shows a schematic representation of a fourth part of the according to 6 shown embodiment of a system according to the invention, which is based on the in 4 shown part was extended.

In order to start the liquefied gas production and to keep it stable, a refrigeration system is provided in Ausspeicherstrang. This refrigeration system can also be used to apply a sometimes necessary energy to start the method according to the first aspect of the invention, by the system 600 is performed.

7 shows a flowchart of an embodiment of a method according to the invention. The flowchart 700 For example, from the devices 120 and 130 to 1 performed and / or controlled.

In a first step 701 a cleaning is carried out in a gas storage (eg a gas storage designed as an underground storage, eg gas storage 110 to 1 , stored natural gas.

In a second step 702 There is a generation of LPG based on the purified natural gas. The generation of liquefied gas can be achieved, for example, by means of the device for producing liquefied gas 130 to 1 be performed and / or controlled. The generation of the liquefied gas takes place in the context of the withdrawal of stored in the gas storage natural gas in a gas storage connected to the gas network, the withdrawal covers, for example, a corresponding need of the gas network. For the purpose of evacuation, an expansion of the natural gas stored in the gas reservoir is required, the natural gas stored in the gas reservoir being reduced in its pressure. In the present case, this is used to use at least part of the natural gas stored in the gas storage to generate liquefied gas.

In an optional third step 703 Storage of the generated liquefied gas, z. B. a storage of the liquefied gas in a separate memory, which is for example covered by the gas storage. Alternatively or additionally, the generated liquid gas or at least a portion of the produced liquefied gas can be stored or stored in a container which is transportable. The transportable container can be transported for example by means of a truck or a train.

The exemplary embodiments of the present invention described in this specification and the respective optional features and properties cited in this context should also be understood to be disclosed in all combinations with one another. In particular, the description of a feature encompassed by an exemplary embodiment is - unless explicitly explained to the contrary - not be understood in the present case that the feature for the function of the embodiment is essential or essential. The sequence of the method steps described in this specification in the individual flowcharts is not mandatory, alternative sequences of the method steps are conceivable. The method steps can be implemented in various ways, so an implementation in software (by program instructions), hardware, or a combination of both to implement the method steps is conceivable.

Terms used in the claims, such as "comprising," "comprising," "including," "containing," and the like, do not exclude other elements or steps. The phrase "at least partially" includes both the "partial" and "full" cases. The expression "and / or" should be understood to mean that both the alternative and the combination should be disclosed, ie "A and / or B" means "(A) or (B) or (A and B)". The use of the indefinite article does not exclude a majority. A single device can perform the functions of several units or devices mentioned in the claims. Reference signs indicated in the claims should not be regarded as limitations on the means and steps employed.

Claims (15)

A method performed by one or more devices (110, 120, 130, 610, 620, 630) comprising: Reducing a pressure of natural gas stored in a gas reservoir (110, 610), the natural gas having a predetermined constant pressure after the reduction; - Cleaning of natural gas stored in a gas storage (110, 610); and - Generation of LPG based on the purified natural gas, wherein the generation of the liquefied gas in the context of the withdrawal of stored in the gas storage (110, 610) natural gas in a gas with the memory (110, 610) connected gas network (650) is performed. Method according to Claim 1 , further comprising: - cooling the purified natural gas prior to the production of the liquefied gas, wherein the cooling of the purified natural gas is effected by means of a first heat exchanger (630-2) and thereby condensing, and wherein a first portion of the cooled natural gas to a second heat exchanger (630-2) 1) is passed and produced by subcooling and expansion liquefied gas; and wherein the cooling of the natural gas by an expansion (630-8, 630-10) by means of a differential pressure, which is applied when storing the stored gas in the gas storage (110, 610), takes place. Method according to one of the preceding claims, wherein the generation of the liquefied gas is carried out substantially simultaneously to a withdrawal of natural gas stored in the gas reservoir (110, 610). Method according to one of the preceding claims, wherein the liquefied gas is generated after passing through at least two heat exchangers (630-1, 630-3), wherein in particular a Joule-Thompson expansion (630-10) of the natural gas is carried out. Method according to one of the preceding claims, wherein the generated liquid gas in a liquid gas storage (140, 640) is stored at least temporarily. Method according to one of the preceding claims, wherein generated for generating the liquefied gas at least partially based on the natural gas that is to be stored on the one hand, and on the other hand to be generated from the liquefied gas. Method according to one of the preceding claims, wherein the first part of the cooled natural gas after a pressure reduction (630-8) in a gas network (650) is auszusicherbar. Method according to one of Claims 5 to 7 wherein storage of the generated liquefied gas causes leakage of an amount of natural gas, wherein the amount of natural gas exiting the liquefied gas storage (140, 640) by heating the stored liquefied gas is usable for further use. Method according to Claim 8 wherein the amount of natural gas for further use to a third heat exchanger (630-4) can be supplied to heat natural gas. Method according to one of the preceding claims, wherein the one or more devices (110, 120, 130, 610, 620, 630) from the gas storage (110, 610) comprises or part of the gas reservoir (110, 610). Method according to one of the preceding claims, wherein the gas storage (110, 610) is a background gas storage. Method according to one of the preceding claims, wherein the cooling is performed at least partially by cooling the natural gas by a refrigeration system (630-6). Method according to one of the preceding claims, wherein the first part of the cooled natural gas by means of a compressor (630-7) is subject to a pressure increase. Device which is adapted or comprises corresponding means, a method according to one of Claims 1 to 13 perform and / or control. A system comprising one or more devices which together comprise a method according to any one of Claims 1 to 13 execute and / or control.

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