AU2014255683B2

AU2014255683B2 - Storage tank for liquefied flammable gases

Info

Publication number: AU2014255683B2
Application number: AU2014255683A
Authority: AU
Inventors: Matthias BRUENTRUP; Josef IRL; Marian Krol
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2013-04-17
Filing date: 2014-04-17
Publication date: 2018-03-22
Anticipated expiration: 2034-04-17
Also published as: CN105358895B; EP2986884A1; AU2014255683A1; RU2678159C2; RU2015149215A; CN105358895A; WO2014170416A1

Abstract

In order to improve storage tanks for cryogenic liquid gases, a full integrity spherical storage tank(80) is proposed, said tank(80) comprising: -an inner tank(82) of cryogenic steel; -an outer tank(83) of cryogenic steel; -a support structure(81); and -an outlet pipe(84) communicating with the interior of the inner tank(82).

Description

The present invention relates to storage tanks for liquefied flammable gases, such as Liquefied Natural Gas (LNG).

Background of the present invention

In order to protect against the catastrophic release of flammable gas from a liquefied flammable gas storage tank, such as an LNG storage tank, safety regulations have been established. Current LNG safety standards provide safety classification of flat bottom LNG storage tanks as single, double and full containment.

This classification does not extend to spherical type LNG tanks. To make the safety designations of all types of tanks comparable, different storage tanks have now been classified according to their level of integrity:

A single level integrity is the lowest classification wherein catastrophic failure of the inner container will cause an uncontrolled spill of natural gas and release of vapour to the atmosphere.

At the double level of integrity, failure of the inner container will not cause a liquid release, but such will result in uncontrolled release of natural gas vapour to the atmosphere.

The highest level is labelled as full integrity and provides for retention of any liquid spill and allows only controlled release of vapour to the atmosphere.

For example, various configurations of flat bottom tanks are shown in FIG. 1 to FIG. 5. FIG. 6 and FIG. 7 show configurations of spherical tanks.

FIG. 1 shows a double level of integrity flat bottom tank 10, having a concrete base 11, an inner tank 12 of cryogenic steel, an outer tank 13 of non-cryogenic steel and an additional tank cup 14 of cryogenic steel. Also shown is an outlet pipe 15.

FIG. 2 shows another configuration of a double level of integrity flat bottom tank 20, having a concrete base 21, and earthen bund 22, an inner tank 23 of cryogenic steel, an outer tank 24 of noncryogenic steel and outlet pipe 25.

FIG. 3 shows a third configuration of a double level of integrity flat bottom tank 30, having a concrete base and liquid containment structure 31, an inner tank 32 of cryogenic steel, an outer tank 33 of non1

2014255683 23 Feb 2018 cryogenic steel and outlet pipe 34.

FIG. 4 shows a full level of integrity flat bottom tank 40, having a concrete base 41, an inner tank 42 of cryogenic steel, an outer tank 43 of cryogenic steel and outlet pipe 44.

FIG. 5 shows a second configuration of a full level of integrity flat bottom tank 50, having an inner tank 52 of cryogenic steel, a non-self standing outer tank 53 of non-cryogenic steel supported on a concrete base and full containment structure 51 and outlet pipe 54.

FIG. 6 shows a single level of integrity spherical tank 60, having steel feet on concrete supports 61, an inner tank and support structure 62 of cryogenic steel, an insulation layer 63 and outlet pipe 64.

FIG. 7 shows a double level of integrity spherical tank 70, having a concrete base and liquid containment structure 71, an inner tank and support structure 72 of cryogenic steel, an insulation i layer 73 and outlet pipe 74.

Currently there are no available configurations of spherical tanks that can be classified as full level of integrity tanks; i.e. that offer a safety level comparable to a full-containment flat bottom tank.

I The full level of integrity is generally required for storage of liquefied flammable gas in populated areas.

This is because single or double integrity tanks do not provide enough of a safeguard against the consequences of a failure of the inner storage container. In particular, those designs do not provide for containment of the vapour release that will occur rapidly in the event of a liquefied gas leak into the area surrounding the tank or the tank secondary containment.

In addition, catastrophic failure of the primary container may result in a large, cold gas cloud that represents a major hazard to the surrounding population because of a heightened risk of fire or explosion. While a full integrity storage tank may release vapour to the atmosphere through pressure release valves, such a release is carried out in a controlled manner and is significantly smaller in quantity.

For all of the above reasons, there remains a need in the art for improvements to storage tanks for cryogenic liquid gases.

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

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Disclosure of the present invention: object, solution, advantages

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

It is an object of a preferred embodiment of the present invention to improve storage tanks for cryogenic liquid gases.

According to a first aspect, the present invention provides a full integrity spherical storage tank comprising:

an inner tank of cryogenic steel; an outer tank of cryogenic steel; a support structure;

an outlet pipe communicating with the interior of the inner tank, and a burst disc in the outer tank.

Unless the context clearly requires otherwise, throughout the description and the claims, the words comprise”, “comprising, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

The present invention provides new configurations of full integrity spherical storage tanks for cryogenic liquid gases. In particular, the present invention provides a full integrity spherical type tank for storage of liquefied flammable gases, such as for storage of liquefied natural gases (LNG).

The full integrity spherical type tank of the present invention is achieved by having both the inner tank as well as the outer tank made of cryogenic steel. The full integrity spherical tank of the present invention comprises feet, in particular made of steel, for example made of cryogenic steel, on a support structure, in particular made of steel, for example made of cryogenic steel, and an outlet pipe communicating with the interior of the inner tank.

The advantages of the spherical tank of the present invention include the following:

Even if there is a leak from the inner tank, the outer tank will not fail from brittle fracture. In other words, by having the outer tank made of cryogenic steel, the design of the spherical tank of the present invention will survive even a catastrophic inner tank leak.

In addition, a burst disc can be provided in the outer tank to allow for controlled release of vapour to a safe location in the event of an inner tank leak. No containment pit, dike or bund is required.

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In addition, by including an Emergency Shut Down (ESD) valve within the inner tank, it is possible to shut down the system in the event of an adjacent piping leak or rupture. This is different from conventional designs of storage tanks where the ESD valve is located externally to the tank.

Such a location for the ESD valve is not a safeguard against a total loss of tank inventory in the event of a pipe rupture or leak upstream of the ESD valve. As noted, by locating the ESD valve internally to the tank according to the present invention, the disadvantages of prior art tank designs are overcome.

Other advantages of the present invention are that the spherical tanks meet the requirements for classification as full integrity storage tanks, and therefore could be used instead of full containment flat bottom tanks currently used in the industry. For many storage capacities, particularly lower capacity storage, spherical tanks are easier, quicker and less costly to construct and install and therefore provide advantages with respect to capital expenditure and construction costs over flat bottom tanks.

In addition, the required footprint for the spherical tanks of the present invention is smaller than that of a flat bottom tank or a standard spherical tank within a dike. This is especially advantageous for

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LNG storage at fuel stations, for example servicing trucks, because the highest level of safety is achieved in the smallest possible area, often surrounded by high population density.

Brief description of the drawings

For a more complete understanding of the present inventive embodiment disclosures and as already discussed above, there are several options to embody as well as to improve the teaching of the present invention in an advantageous manner. To this aim, the present invention is described in more detail below; in particular, reference may be made to the claims dependent on claim 1; further improvements, features and advantages of the present invention are explained below in more detail with reference to a preferred embodiment by way of non-limiting example and to the accompanying drawings taken at least partly in connection with the following description of the embodiments, of which:

FIG. 1 is a schematic layout for a first example of a double level of integrity flat bottom tank according to the prior art;

FIG. 2 is a schematic layout for a second example of a double level of integrity flat bottom tank according to the prior art;

FIG. 3 is a schematic layout for a third example of a double level of integrity flat bottom tank according to the prior art;

FIG. 4 is a schematic layout for a first example of a full level of integrity flat bottom tank according to the prior art;

FIG. 5 is a schematic layout for a second example of a full level of integrity flat bottom tank according to the prior art;

FIG. 6 is a schematic layout for an example of a single level of integrity spherical tank according to the prior art;

FIG. 7 is a schematic layout for an example of a double level of integrity spherical tank according to the prior art; and

FIG. 8 is a schematic layout for an example of a full level of integrity spherical tank according to the present invention.

Detailed description of the drawings;

best way of embodying the present invention

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FIG. 8 shows a full level of integrity spherical type storage tank 80, having steel feet for supporting the storage tank 80 on concrete supports 81, an inner tank 82 of cryogenic steel, an outer tank and support structure 83 of cryogenic steel, and an outlet pipe 84 communicating with the interior of the inner tank 82; in particular, the support structure 81 may be integrally formed with the outer tank 83.

In addition, the spherical tank 80 includes an in tank (= located internal to the inner tank 82) Emergency Shut Down (ESD) valve 85, which is connected to the outlet pipe 84. This ESD valve 85 enables a shut down in the event of an adjacent piping leak or rupture.

A burst disc is provided in the outer tank 83, said burst disc allowing for controlled release of vapour to a safe location in the event of a leak of the inner tank 82.

The storage tank 80 of FIG. 8 is provided for the storage of cryogenic liquid gases, in particular for 15 the storage of liquefied flammable gases, for example for the storage of liquefied natural gases (LNG), such as for the LNG storage at fuel stations for servicing trucks.

It is anticipated that other embodiments and variations of the present invention will become readily apparent to the skilled artisan in the light of the foregoing description, and it is intended that such embodiments and variations likewise be included within the scope of the present invention as set out in the appended claims.

List of reference numerals full integrity spherical storage tank support structure inner tank outer tank outlet pipe emergency shut down (ESD) valve

Claims

Claims

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1. A full integrity spherical storage tank comprising: an inner tank of cryogenic steel;

an outer tank of cryogenic steel; a support structure;

j - an outlet pipe communicating with the interior of the inner tank, and a burst disc in the outer tank.
2. The full integrity spherical storage tank according to claim 1, further including an emergency shut down valve.

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3. The full integrity spherical storage tank according to claim 2, wherein the emergency shut down valve is connected to the outlet pipe.
4. The full integrity spherical storage tank according to claim 2 or 3, wherein the emergency shut j down valve is located inside the inner tank.
5. The full integrity spherical storage tank according any one of claims 2 to 4, wherein the emergency shut down valve enables a shut down in the event of an adjacent piping leak or rupture.

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6. The full integrity spherical storage tank according to any one of claims 1 to 5, wherein the burst disc allows for controlled release of vapour.
7. The full integrity spherical storage tank according to claim 6, wherein the vapour is released to a i safe location in the event of a leak of the inner tank.
8. The full integrity spherical storage tank according to any one of claims 1 to 7, wherein the support structure is made of cryogenic steel.

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9. The full integrity spherical storage tank according to any one of claims 1 to 8, wherein the support structure is integrally formed with the outer tank.
10. The full integrity spherical storage tank according to any one of claims 1 to 9, being provided for the storage of cryogenic liquid gases.
11. The full integrity spherical storage tank according to claim 10, being provided for the storage of liquefied flammable gases.

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12. The full integrity spherical storage tank according to claim 11, being provided for the storage of liquefied natural gases (LNG).
13. The full integrity spherical storage tank according to claim 12, being provided for the LNG storage at fuel stations.
14. The full integrity spherical storage tank according to claim 13, being provided at fuel stations for servicing trucks.

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FIG. 2

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FIG. 3

FIG. 4

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PIG. 5

FIG. 6

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FIG. 7

FIG. 8