DE1255904B - Underground tank for liquid gases and process for its manufacture - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl:

E04h

German class: 37 f - 7/02

Number: 1255 904

File number: C 23847 V / 37 f

Filing date: April 10, 1961

Opened on: December 7, 1967

The invention relates to a container which is used to hold a liquefied gas and whose wall is formed by the soil itself containing a frozen liquid as a seal and which is provided with a device for introducing and discharging the liquefied gas, as well as a Method of manufacturing such a container.

By the term "liquefied gas" or "liquefied gas" is meant a liquid that at atmospheric Pressure evaporates at a temperature below ambient.

It is known to produce liquefied natural gas and liquefied petroleum gases in underground cavities deposits that either originated naturally or were created in rock that is impermeable to fluids are. Similar known underground storage systems have been provided in salt formations. At the places where storage is intended, however, there are useful soil formations not always available.

It is also known to create underground containers for receiving liquefied gases that exclusively Accessible via a narrow connecting shaft or tunnel opening into the surface of the earth are and their wall by containing a frozen liquid as a seal Soil itself is formed, as is also the case with the earth container mentioned at the beginning.

These well-known underground containers are located in the ground at a distance from the surface of the earth, with the result that their manufacture causes considerable difficulty and the manufacturing cost such containers are relatively high. These containers are also completely in self-contained system that is not in contact with the outside atmosphere. For this Such a known container is based on a fan, a compressor and a cooling tower comprehensive system assigned so that the constantly evolving in the upper part of the container in question Amount of steam can be discharged from the container space. This brings another significant Increase in price with itself.

The invention is based on the object of reducing the production costs of a container of the type specified at the beginning Kind of decrease significantly.

This object is achieved according to the invention in that the container has the shape of a through a thermally insulated roof has a covered recess on the surface of the earth and has an opening, by means of which the gas pressure of the liquefied gas filled into the container can be compensated.

Underground tanks for liquefied gases and processes
for its manufacture

Applicant:

Conch International Methane Limited,

Sandringham House, Nassau (Bahama Islands)

Representative:

Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse
and Dr. E. v. Pechmann, patent attorneys,
Munich 90, Schweigerstr. 2

Named as inventor:
Cedomir M. Sliepcevich,
Norman, OkIa. (V. St. A.)

Claimed priority:

V. St. v. America April 20, 1960

The inventive feature that the container has the shape of a thermally insulated Roof covered recess has in the surface of the earth, the advantage is achieved that the creation of a such a container, which is easily accessible, accomplished with simple means and in a very short time can be. By the further inventive feature that the container to compensate for the Gas pressure of the absorbed liquefied gas has an opening for pressure equalization, is achieved that the container for storing the liquefied gases no additional systems for discharging must be assigned to the constantly evolving amount of steam, as is the case with the known such containers is the case.

With the container according to the invention, large quantities of liquefied gases can be stored particularly cheaply will. A container designed according to the invention can also be built up completely safely, because if part of the container wall collapses due to careless work, the on the container bottom standing construction workers can easily free and not, as with the well-known underground Container systems, possibly completely buried by the collapsing earth.

Although it is already part of the state of the art, a container that holds a liquid

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To give the shape of a recess on the surface of the earth. In this known container, however the wall is not formed by the soil itself, which contains a frozen liquid as a seal, rather, the container wall is formed by a concrete lining of the soil, which is still must be provided with a waterproof coating to prevent leakage of the stored liquid, which is primarily oil. This known container has so in comparison a largely different structure to the container according to the invention and is suitable apart from the fact that the construction costs of such a container in terms of the concrete lining and the dense coating are relatively high in view of the dangerous thermal stresses poor in concrete for absorbing liquefied gases.

Prerequisite for proper operation with a container designed according to the invention it is that the liquid contained in the soil and acting as a seal solidifies at the evaporation point of the stored liquefied gas is. Usually this liquid consists of water, so that in the case where the earth layer concerned contains water by itself, no additional liquid has to be added to the soil layer. However, if the layer of earth in which the container is to be placed is dry, it is necessary to use the Earth with water or another liquid that solidifies at the evaporation point of the liquefied gas, to soak. Such a liquid can be made up of crude oil or a fraction or a residue Heavy oil consist.

The recess itself can be a natural hole in the surface of the earth or artificial by excavation or blowing up.

The thermally insulated roof covering the recess can be made of any suitable base material such as Steel, especially mild steel, aluminum or wood are made. If wood is used, it has to go to the Connections must be sealed accordingly. This basic material is then combined with a thermal insulating layer covered. This layer can be at the top or at the bottom or be arranged on both sides of the roof. If the insulation is under the roof, it can be in in direct contact with the underside of the roof or at a short distance from the underside of the roof be arranged.

Appropriately, the surface of the earth near the edge of the thermally insulated roof should also be isolated. This insulation can be used as a continuation of insulation on the top of the roof be executed.

Suitable thermal insulation materials for the roof and the surface of the earth adjacent to its outer perimeter are perlite, glass wool, honeycomb material made of paper and foam-shaped plastics such as foam-shaped ones Polystyrene and polyurethane. The surface of the earth surrounding the outer perimeter of the roof can also be insulated with dry clapboard, sand or concrete.

If the soil layer is such that when liquefied gas is first poured into the container a considerable part of this gas is lost through penetration into the surrounding soil two ways to prevent this from happening.

Either the surrounding soil can be frozen before the liquefied gas enters the container is filled, which can be done by allowing a coolant, such as cold salt water, through into the ground Introduced tubes is passed through. Alternatively, this can also be the recess surrounding soil additionally be sealed by a thin metal foil, or it can be a Find a layer of a heat-insulating material that is capable of removing the liquefied gas from to separate from the ground. Suitable materials are glass wool, very fine perlite or foam-shaped Plastics. Glass wool is particularly suitable as a separating layer because it is in the glass wool penetrating liquefied gas vaporizes and creates a counter pressure that allows further penetration Liquefied gases prevented. In addition, the glass wool can be applied directly to the inner wall of the recess be placed so that it comes into contact with the liquefied gas to be stored. The glass fibers are pressed firmly against the ground by the pressure of these liquefied gases and form an effective seal.

The heat-insulating layer separating the liquefied gas from the earth does not need to be too resistant, because when the container is in use for some time, the temperature of the surrounding soil gradually falls, so that the heat transfer to the liquefied gas becomes less and less. As a result, the insulation of the ground gets better and better over time, and after a few years the heat transfer is negligibly small.
The pressure equalization opening of the container, through which the gases produced in the container can escape, can be connected to a gas storage system or to a reliquefaction system. It is of course also possible to burn off the gases escaping through this opening as a torch.

A pressure control device is expediently attached to the pressure equalization opening of the container connected, with which the gas pressure in the container can be monitored. This makes it possible to use the Maintain a slight overpressure inside the container, through which air can penetrate into the Container and thus the formation of an explosive air gas mixture is prevented.

A method according to the invention for producing the container described is that on at a point in the ground containing the liquid intended for sealing, the recess made of the earth's surface, then with the thermally insulated one that allows gas pressure equalization Covered roof and then the liquefied gas is poured into the recess.

If the soil in which the recess is to be provided is very sandy, it is expedient at the point on the earth's surface intended for the recess as an alternative to the one described Process only those intended for sealing, naturally existing or artificial supplied liquid solidified by freezing and then within the solidified area made the recess, after which this with the gas pressure equalization permitting heat insulating Roof is covered. This has the advantage that when excavating the recess the container walls formed by the soil

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cannot collapse despite the sandy nature of the earth.

As already mentioned, water can be used as the liquid, for its solidification a coolant circulating in the ground is used prior to making the recess.

The invention is illustrated below with reference to schematic drawings of several exemplary embodiments explained.

F i g. 1 and 2 show vertical sections of the invention Earth containers;

Fig. 3 shows a vertical section through a Part of a thermally insulated roof covering an earth container according to the invention, while

F i g. 4 shows, on an enlarged scale, a vertical section through the upper edge of this according to the invention Earth container with the connection to the thermally insulated roof shows.

According to FIG. 1, the earth container according to the invention has the shape of a recess 2 on the surface of the earth 1. The soil surrounding the recess 3, which forms the wall of the earth container, is interspersed with a liquid that acts as a seal and through cooling devices in the frozen State has been brought. A thermally insulated roof 4 covers the recess 2, the roof 4 even by a layer 5 of a heat insulating material, e.g. B. of perlite or glass wool, covered is. This heat insulating layer 5 extends beyond the roof 4 and is with the to Roof edge adjacent area 6 on the earth's surface 1.

The earth container shown is a device for introducing and emptying the liquefied gas assigned. According to FIG. 1, this device comprises a filling pipe 7, which extends through the thermally insulated Roof 4 extends to just above the container bottom. In addition, an emptying pipe 8 is provided, which is connected to a pump 9 below the liquid level 11.

The container also has a pressure equalization opening on, which is formed by a pressure equalization tube 10, which is also insulated by the heat Roof 4 opens through into the interior of the container.

In the case of the one shown in FIG. The container shown in FIG. 2, which is similar to the container according to FIG. 1 is formed, is the Inner surface of the recess 2 by a layer 12 of a heat insulating material in the form of a glass fiber layer covered. This means that it is not necessary to fill the container with the liquid gas to freeze the surrounding soil 3, because the glass fiber layer 12 prevents the liquefied Gas penetrates through the not yet frozen layer of soil 2.

The device for introducing and discharging the liquefied gas comprises in the case of the one in FIG. 2 shown Container a single tube 13 which is passed through the heat-insulated roof 4 and in a filler neck 14 and opens into an emptying neck 15.

Although the containers shown in Figs. 1 and 2 are basin-shaped, it should be noted that they can also be cylindrical or rectangular.

The thermally insulated roof 4 comprises according to FIG. 3 a steel cover 16 with an insulating layer 17, which is spaced apart by means of supports on the underside of the cover 16.

The insulation is expediently impermeable to gases and can, for example, be made of foam-shaped Plastics with closed pores or filled honeycomb material consist of paper. The cavity between the cover 16 and the insulating layer 17 increases the thermal insulation properties of the Roof construction.

According to FIG. 4 is the cover 16 with the heat insulating layer 17 on the upper edge of the container embedded in the ground 3 to provide an effective seal against the edge of the roof 4 To create the interior of the container. This seal also includes a layer of cement 18 overlying the area the surface of the earth is applied, which is adjacent to the edge of the container. In addition, the Cement layer 18, a thermal insulation layer 6 ', for example made of perlite or glass wool, which has a a short distance also rests on the cover 16. If necessary, the top area can also be used 19 of the soil 3 are kept frozen by artificial means.

The containers described can, if necessary, be made very large, with their diameter can be between about 15 and about 60 m.

A diameter of 30 m has proven to be advantageous. Similarly, the depth of the container may vary between about 15 to about 60 m, typically a depth of about 20 to 30 m is chosen.

If the earth's surface 1 is isolated on the outer periphery of the roof 4, depends on the area for which this Isolation is required from the specific liquefied gas stored in the container and from the special prevailing atmospheric conditions. In general, it becomes the outer circumference of the roof 4 surrounding area of the earth's surface 1 to a distance of about 4.5 to 15 m insulated.

Claims (8)

Patent claims: 1. To hold a liquefied gas container, the wall of which is through the a frozen liquid as a seal containing soil itself is formed and with a Device for introducing and emptying the liquefied gas is provided, characterized in that that the container is in the form of a recess (2) on the surface of the earth covered by a thermally insulated roof (4) (1) and has an opening (pressure equalization tube 10) through which the gas pressure of the in the Container filled liquefied gas can be compensated. 2. Container according to claim 1, characterized in that the earth's surface (1) in the vicinity the edge of the thermally insulated roof (4) is thermally insulated. 3. Container according to claim 1 or 2, characterized in that the recess (2) surrounding it Earth (3) is additionally sealed by a thin metal foil. 4. Container according to one of claims 1 to 3, characterized in that the inner surface of the Recess (2) is covered by a layer (12) made of a heat insulating material. 5. Container according to one of claims 1 to 4, characterized in that the opening of the Container connected to a pressure control device monitoring the gas pressure in the container is. 6. A method for producing a container according to any one of claims 1 to 5, characterized in that that the recess (2) on the surface of the earth at a location of the soil (3) containing the liquid intended for sealing (1), then with the thermally insulated one that allows gas pressure equalization Roof (4) covered and then the liquefied gas is poured into the recess (2). '' 7. A method for producing a container according to any one of claims 1 to 5, characterized in that that at the one for the recess (2) certain point on the earth's surface (1) the naturally existing intended for sealing or artificially supplied liquid solidified by freezing and then the recess (2) produced within the solidified area and this with the gas pressure equalization permitting thermally insulated roof (4) is covered. 8. The method according to claim 7, characterized in that the sealing liquid Water and a circulating coolant is used to solidify it. Considered publications:
U.S. Patents Nos. 1,360,170, 2,932,170. 1 sheet of drawings 709 707/42 11. 67 Bundesdruckerei Berlin