JPS59164499A - Double shell low temperature tank structure - Google Patents

Abstract

PURPOSE:To prevent breakdown of tank body by supporting the outer tank roof with liquid prevention bank thereby preventing destruction of outer tank even when it is damaged. CONSTITUTION:When the inner tank 5 is cracked due to earthquake while the outer tank 3' is damaged due to thermal shock to flow out the stored liquid 6, the entirety of outer tank is never destroyed because the outer tank roof 3'' installed with various pipes and machineries is supported by a liquid prevention bank 8', and never cause secondary or tertiary disaster. When low temperature liquidized gas 6 starts to flow out through crack, it is detected by a sensor 17 to input a signal to a controller 19 thus to remote open a valve provided in exhaust gas pipe 15. Liquidized gas 6 is gasified to increase pressure in a void space 9' then discharged through a discharge gas pipe 15 to a vent stack 16.

Description

[Detailed Description of the Invention] Technical Classification and Field The disclosed technology belongs to the field of liquid barrier structure technology for storage tanks for low-temperature and liquefied gases such as LPG and LNG.

〈Explanation of the gist〉 Therefore, the invention of @ is that the inner tank made of low-temperature material such as 9%Nl steel or aluminum alloy is connected to the inside of the carbon steel outer tank through a heat insulating material such as 9% Nl steel or aluminum alloy. An invention relating to a double-shell low-temperature tank structure in which a concrete dike is installed around the entire circumference of the tank body through a void space of a cylindrical space on the outside of the outer tank side plate of the tank body. In particular, the void space of the nuclear liquid dike is narrowed and the height is extended to the outside of the outer tank side plate, so that the capacity is sufficiently l-1. The roof of the outer tank should be installed close to the top of the dike, and the roof of the outer tank should be installed on the top of the dike, either with a gap or sealed all around. This invention relates to a double-shell low-temperature tank structure in which an emergency leakage gas discharge device such as a vent stack or an exhaust gas pipe communicating with exhaust gas treatment equipment such as a flare stack is provided in the soil part of the space.

<Prior art> As is well known, low-temperature liquefied gas tanks such as LNG and LPG are becoming larger in size reflecting the recent energy situation, and flat-bottomed cylindrical tanks are being used in view of ease of construction, cost, operating conditions, capacity, etc. Double-shell cryogenic tanks with dome roofs were widely adopted, and
As shown in the figure, an outer tank 3 made of carbon steel is installed on a foundation 2 provided in a setting area 1, and an inner tank made of 9% Nl steel, aluminum alloy, etc. A tank 5 is provided, and in the inner tank 5 1 c of low-temperature liquefied gas 6 such as LNG, LPG, etc.
I try to pay the savings and drive.

Therefore, if a load such as an earthquake is applied to the tank body 7 during operation and the stored liquid leaks unexpectedly, the tank body 7 is spaced a predetermined distance apart from the outside of the tank body 7 to prevent it from leaking over a wide area and causing a secondary disaster. A concrete liquid barrier 8 is installed at the site to form a void space 9, which is a storage space for the total amount of liquid stored, between the tank body 7 and the tank body 7.

<Problems with the Prior Art> However, in the structure of the conventional double-shell cryogenic tank described above, the tank body 7 and the dike 8 are substantially separated and separated, so that unexpected problems may occur. If a defect occurs in the inner tank 5 and the low-temperature storage liquid 6 flows out and comes into contact with the outer tank 3, the outer tank 3 may be damaged due to the thermal shock or lack of low-temperature toughness of the outer layer 3. In this case, the weight of the outer tank plain wood, roof, piping, and attached equipment is considerable, so there is a risk that not only the VC 43 but also the roof and attached equipment will collapse as shown in Figure 2. There was a certain drawback.

This (1) caused the problem that the stored liquid 6 leaked out all at once, causing the dike 8 to overflow due to the energy of the spill, potentially causing secondary and tertiary disasters.

In particular, there is a high probability that the effluent gas will rise and touch the roof of the outer tank, which has the disadvantage that there is a risk of damage to the outer tank and many of the attached equipment installed in the outer tank.

Furthermore, even if the outer tank 3 had not been damaged in this way, as shown in FIG. 6 is a dike 8, an outer tank 3, a tank 3, and a void space 9 at room temperature.
It absorbs the sensible heat of the gas inside and evaporates, forming gas 6 as shown in Figure 4.
′ increased, overflowing the dike 8, and gaining heat from the outside, which could cause ignition, explosion, and fire as shown in Figure 5.

<Object of the Invention> The object of the invention of this application is to solve the problem of mud leakage from a double-shell cryogenic tank having a liquid barrier based on the above-mentioned prior art, and to Although the leakage of stored liquid is caused by an unavoidable f@@bank, it is ensured and safely stored and discharged in the void space, and the tank roof is supported by the liquid protection bank to prevent damage to the tank body. It is an object of the present invention to provide an excellent double-shell cryogenic tank structure that is beneficial to the field of tank application in industry.

<Structure of the Invention> In accordance with the above-mentioned objective 1, the structure of the invention of this application whose gist is the scope of the above-mentioned claims is to solve the above-mentioned problems by storing low-temperature liquefied gas such as LNG or LPG in a double-shell cryogenic tank. If a crack or the like occurs unexpectedly in the inner tank during liquid storage operation, and the stored liquid flows out from the inner and outer tanks into the void space, the outer tank will be damaged.
The gas is gasified in the void space between the dikes installed in close proximity to each other, collected by the leakage gas exhaust device installed above the void space, and sufficiently disposed of by the flare stack, vent stack, etc. outside the tank. To prevent secondary and tertiary disasters caused by gas spreading outside the dike and igniting, in this case, the outer layer roof should be supported on the top of the dike, so that even if the outer tank υζ is accidentally damaged, it will not cause a secondary or tertiary disaster. Preventing the tank from collapsing,
To prevent damage to the outer tank roof and attached equipment, and
Technical means to seal the support bearing part at least in abnormal situations, and to install insulation material on the inner surface as necessary, to improve the low temperature resistance reliability of the structure and further weaken the thermal shock of the support part. This study included the following.

<Embodiment - Configuration> Next, an embodiment of the invention of this application will be described as follows based on the drawings from FIG. 6 onwards. Note that the same parts as in FIGS. 1 to 5 will be described using the same reference numerals.

7' is a double shell low temperature tank which constitutes the gist of the invention of this application, and in the illustrated embodiment, it is used, for example, for LNG storage;
A liquid barrier 8' made of concrete is constructed integrally with or around the concrete foundation 2' of the setting area 1.

Inside the liquid barrier 8', an outer tank 3' of the tank body is provided via a void space 9' which is narrower than a conventional general void space but has sufficient height, and inside the outer tank 3', there is a side wall such as perlite. An inner tank 5 is installed via a bottom cold insulating material 4 and a bottom cold insulating material 4' such as foamed concrete, and is operated to store LNG 5.

For convenience of illustration, pipes, manholes, and other accessories are omitted.

Therefore, in the invention of this application, the outer tank side plate is the liquid barrier 8.
The end of the outer tank roof 3'' is fixed to the top of the nuclear liquid dike 8', and its phraseological aspect is the seventh.
As shown in the figure, the beams 10 of the roof are connected to the body plates 11'VC, and the body plates 11 are fixed to the top 8'' of the dike 8', and these beams 10 are covered with the cutouts 12 to form a continuous roof. Therefore, the void space 9' is sealed by the liquid barrier 8', the outer tank 3', the cover 12, and the body plate 11.

However, I will make it an open type according to the design and seal it as appropriate5.
1/! :Means such as providing a shutoff valve may be used.

If there is a risk that these support materials and cover materials may become brittle due to leaked gas, use a low temperature material such as Nl steel or aluminum alloy, or provide a low temperature resistant lining.

That is, as in the embodiment shown in FIG. 8, supporting material tc urethane heat insulating material 13 and the like are added in preparation for unexpected situations to cope with leakage gas contact and to cope with thermal shock.

As shown in detail in FIG. 6, a ring pipe or nozzle 14 as an emergency leakage gas discharge device having a predetermined number of suction ports is installed at any location in the void space 9'. An exhaust gas pipe 15 is connected and extended through the top part 8'/ of the liquid barrier 8' and the continuous cover part 11 of the outer tank roof 3, and a vent is provided at a predetermined position outside the liquid barrier 8'. It is connected to the stack 16 via a suction pump (not shown).

In this case, depending on the design, the exhaust gas pipe 15 may be connected to the outer tank interior space at the same time as shown by the dotted line in FIG.

A well-known suitable leakage gas (liquid) sensor 17 is installed at the bottom of the void space 9' or inside the cold storage 4 in the outer tank, and is connected to a control device attached to the vent stack 16 via a cable 18. 19 to control the start and stop of the suction pump.

<Embodiment - Effect> In the above-described configuration, during the process of storing LNG 6 in the double-shell low temperature tank 7 and performing receiving and discharging operation (during the process, an unexpected crack occurs in the inner tank 5 due to an earthquake or the like, and the outer tank 3' Even if damage 20 occurs due to thermal shock and the stored liquid 6 begins to flow out, the outer tank roof 3" on which various pipes and equipment are attached, as described above,
is supported by the dike 8' by the supporting material 10, so even if the outer JlvJ3' deteriorates as shown in FIG. 2, the roof is supported by the dike 8', so the entire outer tank Therefore, there is no risk of secondary or tertiary damage such as further destruction of the inner tank due to wear and tear, and the original structure can be easily repaired.

As shown in FIGS. 1I and 12, when the low-temperature liquefied gas 6 of LNG begins to flow out from the crack 20, the sensor 1γ immediately detects this and sends a detection signal to the control device 19 via the cable 18. is input, thereby manually or automatically remotely opening the valve provided in the exhaust gas pipe 15 and starting the function of the exhaust gas treatment system.

Therefore, when the pressure inside the void space 9' (and the outer tanks 3', 3'') increases due to the outflow gasification of the liquefied gas 26, the gas is discharged to the vent stack 16 via the exhaust gas vibrator 15 due to this pressure and is processed as specified. and does not dissipate around the tank at all.

Therefore, release of evaporative gas outside the system, ignition, explosion, etc. do not occur.

During this time, the emergency device is operated to transfer the remaining liquid 6 in the inner tank 5 to another tank, and after a predetermined purge, inspection and repair of the damaged area is started as appropriate.

<Other implementations 0> It goes without saying that the embodiments of the invention of this application are not limited to the above-mentioned embodiments. For example, if the emergency gas discharge device is complete, the insulation material of the outer tank roof support material It may be possible to do without attaching an attachment, or to install a freeze prevention hole on the tank foundation, or to take the target tank underground (in this case, the underground concrete wall is equivalent to a dike), or to prevent voids. Various aspects can be adopted, such as providing a safety valve in the space.

<Effects of the Invention> According to the invention of this application, basically, even if low-temperature stored liquid accidentally leaks from the inner tank of a double-shelled low-temperature tank and the outer tank is damaged due to thermal shock, etc., the outer tank roof will remain intact. Because it is supported by the dike, not only the outer tank itself, but also the outer membrane receiver, pipes, and attached equipment can be inspected and repaired without damage, which has the excellent effect of preventing major damage. It is played.

In addition, as the gas leaks into the void space formed between the dike and the outer tank, as it rises, it is collected and completely discharged by the emergency leakage gas exhaust device to prevent it from leaking out of the system from the dike. As a result, an excellent effect can be achieved without causing any risk of secondary or tertiary disasters such as diffusion, ignition, or explosion.

Furthermore, by supporting the outer tank roof end on the top of the dike and sealing it at least in the event of an abnormality, it is possible to ensure that leaked gas does not leak outside the dike, and by lining the supporting portion with a heat insulating material. This has the advantage that the support part is less likely to be damaged by thermal shock ((), and its durability is improved.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a double-shell cryogenic tank based on the prior art;
Figure 2 is a cross-sectional view explaining damage to the tank body, Section 3.4.5
Figure 6 is a side view explaining the disaster caused by the leaked liquid, Figure 6 and subsequent figures are detailed explanatory views of the invention of this application, Figure 6 is a sectional view of the double shell low temperature tank, and Figure 7 is an enlarged cross section of the outer tank roof support. Figure, 8th
The figures are a sectional view of another embodiment equivalent to Fig. 7, Fig. 9.1o is a side view illustrating damage to the tank, and Figs. 11, 12, and 13 are side views illustrating leakage gas discharge. 3'...outer tank, 4.4'...insulation material 5
・Inner 4th tank, 9'...Hoid space, 8'...Dike, 7'...Double shell low temperature tank, 8"...Top, 3"...Outer tank roof, 14...Emergency Leakage gas exhaust device, 13・Insulation (Applicant: 111 Saki Heavy Industries Co., Ltd.

Claims (2)

[Claims] (1) An inner tank is installed through a heat insulating material to the outer tank.
In a double-shell cryogenic tank structure in which a liquid barrier is installed surrounding the outside of the outer tank side plate M + C void space, the nuclear liquid barrier is installed close to the outer tank side plate with the void space narrowed. , its height is set to near the top of the outer tank side plate, and the outer tank roof is supported by the upper end 6 of the liquid barrier, and an emergency leakage gas discharge device is provided above the void space. A double-shell cryogenic tank structure characterized by: (2) In a double-shell cryogenic tank structure in which an inner tank is provided to the outer tank via a heat insulating material, and a liquid barrier is installed surrounding the outer tank side plate via a void space, nuclear protection The liquid bank is provided close to the outer tank IP+U plate by narrowing the void space, and its height is set to near the top of the outer tank side plate, and the outer tank roof is placed all over the upper end of the liquid bank. 17. A double-shell cryogenic tank, characterized in that the tank is supported in a sealed manner and a heat insulating material is provided on the support portion, and an emergency leakage gas exhaust device is provided above the void space. structure.