JPS5926697A - Low-temperature double-shell tank construction - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The disclosed technology belongs to the technical field of measures against leakage of storage tanks for storing low-temperature liquefied gases such as LNG.

Therefore, in this invention, a cold insulator such as urethane is attached to the inner surface of an outer tank made of prestressed concrete, etc., and a cylindrical space is created between the inner tank made of aluminum alloy or the like and the cold insulator. The invention relates to a flat-bottomed cylindrical low-temperature double-shell tank structure formed and mounted on a foundation, in particular, a leak detection device provided in the space is connected to a control device, so that the control device or the liquid This relates to a low-temperature double-shell tank structure in which a pump in the middle of the piping connected to the nitrogen source is activated, and liquid nitrogen is supplied from a nozzle pipe ringed at the bottom of the space to evaporate the leaked liquid instead of evaporating it. It is an invention.

As is well known, as the storage capacity of low-temperature liquefied gas storage tanks such as LNG increases, it has become necessary to take special measures against hot water leakage.

For example, there is a method of installing a dike around the tank.
In addition to occupying a large area, if the leaked high-temperature liquid evaporates quickly and gas diffuses to the downstream area of the dike, it has the disadvantage of causing a serious disaster due to ignition, and the disadvantage is that the recovery rate of the leaked liquid is also low. There was also the problem of contamination with sand, mud, etc., which required separation.

In addition, firefighting facilities, etc. required dog crews, and their management, maintenance and inspection were also required, making operation and maintenance generally cumbersome.

The purpose of this invention is to solve the problem of leakage of low temperature liquid stored in a low temperature liquid storage tank based on the above-mentioned prior art, and to solve the problem of leakage of low temperature liquid stored in the inner tank and to secondary storage in the outer tank. To provide an excellent low-temperature double-shell tank structure that can be used for alternative evaporation using liquid nitrogen to prevent disasters from occurring to the surrounding area, can be recovered quickly, and does not cause poor purity, and can be beneficial to the field of tank utilization in the energy industry. It is something.

The structure of the present invention in accordance with the above-mentioned purpose is to fill the space between the outer tank inner surface cold insulating material provided on the foundation and the low temperature liquid storage inner tank with nitrogen gas during normal operation of the tank to prevent unexpected leakage of low temperature liquefied gas. If the stored low-temperature liquid leaks out from the inner tank, it will be secondarily stored in the space between the rigid outer tank support cold insulator and the inner tank, and the leakage will be immediately detected in the space, and the control device will be activated. Liquid nitrogen is supplied to the lower part of the space by a pump from a liquid nitrogen source through the tank, and since the liquid nitrogen's low temperature of -196°C is lower than that of the storage leakage effluent, the liquid nitrogen preferentially evaporates, and therefore The leaked liquid is difficult to evaporate, and the gas that increases pressure in the space is released outside the tank, and the released gas is mainly composed of inert nitrogen gas components, so that it does not cause any disaster to the surrounding area in principle. The gist is that technical measures have been taken.

Next, one embodiment of the present invention will be described below based on the drawings.

Reference numeral 1 denotes a low-temperature double-shell tank that constitutes the gist of the present invention, and in this embodiment, it is used for LNG storage, and has a flat bottom cylindrical dome roof type and is not provided with a liquid barrier.

An outer tank 4 made of prestressed concrete IJ-G is made of a pressure-resistant and rigid structure on the foundation 3, and a dome roof 5 made of low-temperature steel is provided from the top of the outer tank 4. Urethane cold insulation materials 6 and 7 are attached to the set thickness.

On the other hand, on the foundation 3 is an inner tank 1 in which a bottom cold insulating material 8 of foamed concrete is laid and a bottom plate 9 made of aluminum alloy is installed.
0 is erected and has a dome roof 11 integrally.

Therefore, a space 12 is formed between the inner tank 10 and the internal cold insulating material 6 of the outer tank 4, and communicates with the ceiling space 13.

In this case, depending on the design, the space 12 may be filled with an inexpensive granular heat insulating material such as pearlite to improve heat insulation and reduce costs. 8 and a part thereof is connected to a pit 14 provided in the foundation 3 through a hole, and the pit 14 is connected to another tank by a pipe 17 with a pump 16 interposed through a filter 15. There is.

Further, at the bottom of the space 12, as shown in detail in FIG.
A ring-shaped stainless steel nozzle pipe 19 having barrels 18, 1B, . It is connected to a liquid nitrogen tank 21 via 20.

A check valve 22, a pump 23, and a three-way valve 24 are installed in series in the piping 20 from the tank side, and a three-way valve is branched from the piping 20 to the dome roof 5. A check valve 26 is connected to the pipe 25 connected to the tank 24 from the tank side.
A pump 27 and an evaporator 28 are interposed in series.

Further, a well-known hot water outflow detector 29 is attached to the lower part of the space 12, and is connected to a control device 31 via wiring 30.

Thus, a wiring 32 is connected to the pump 2 from the control device 31.
3 and 16, and wires 33 and 34 are connected to the three-way valve 24.
and the pump 27.

In the above configuration, in the normal operating state, the control device 31 operates the three-way valve 24 to connect the piping 20.25 to operate the evaporator 28, and the liquid nitrogen source 2
Dry nitrogen gas from 1 is filled into the space 12 from the nozzle pipe 19 via the check valve 26 and the piping 20 to operate in preparation for unexpected leakage, and the LNG is supplied and discharged by a receiving device (not shown). .

Furthermore, in the system for supplying dry nitrogen gas to the space 12, a free tank may be installed as appropriate to control the pressure of the nitrogen gas.

As a result, cracks or the like occur unexpectedly in the inner tank 10, and LNG leaks into the space 12.

Then, the detector 29 detects this and inputs a detection signal to the control device 31 via the wiring 30, which activates the relay to stop the pump 27, and also switches the three-way valve 24 to activate the pump 23.16. do.

Therefore, liquid nitrogen is supplied to the pump 23 from the liquid nitrogen source 21.
It passes through the pipe 20 and is supplied to the lower part of the space 12 through the nozzles 18, 18, etc. of the ring-shaped nozzle pipe 19.

The LNG 2 also leaks into the space 12, but if both of them touch the side cold insulating material 6 and evaporate, the LNG will be 1162
On the other hand, since liquid nitrogen has a much lower temperature of -196°C, it selectively absorbs heat input from the outside and preferentially evaporates into gas.
hardly evaporates and remains in a liquefied state.

Then, it accumulates in the pit 14 and passes through the pipe 17 to the pump 1.
6, the liquid in tank 1 is recovered to an adjacent tank or the like, or the liquid in tank 1 is recovered to another tank by operating the original shipping pump in tank 1.

Also, the vaporized nitrogen gas increases the pressure in the space 12, but the safety valve 3
5 and released into the atmosphere.

In this case, since the side cooler 6 is stretched in a liquid-tight manner, the nitrogen gas and the effluent do not come into contact with the outer tank 4, and therefore the outer tank will not be damaged due to thermal shock or thermal stress. Moreover, the cold insulation function of the side cold insulation is not impaired due to the vaporization of nitrogen gas.

Also, during this period, the inner tank 10 is removed as soon as possible by the dispensing device.
The LNG inside is transferred to another tank, and when all the LNG is empty, the pumps 23 and '16 are stopped via the control device 31, and predetermined repairs are performed.

It goes without saying that the embodiments of this invention are not limited to the above-mentioned embodiments, and various embodiments may be adopted, for example, the two pipes 14, piping 17, etc. may be omitted, or the object may be LPG. It is possible.

As mentioned above, this invention basically allows the low-temperature liquid flowing out from the inner tank to be stored secondary in the space between the cold insulation material inside the outer tank and the inner tank without providing a liquid barrier. Not only can the tank area be made smaller, but it also has the effect of not causing an open disaster to the surrounding area.

In addition, a nozzle pipe connected to a liquid nitrogen source is provided at the lower part of the space, and the nozzle pipe is connected to a pump connected to a leak detection control device, so that accidental leakage from the inner tank to the space is possible. Even if low temperature liquid leaks out and is stored in secondary storage,
Upon this detection, liquid nitrogen is supplied to the space, and since liquid nitrogen is lower in temperature than the low temperature liquid and liquid nitrogen that coexist in the space, it is preferentially turned into a gas to prevent the evaporation of the low temperature liquid flowing out of the hot water. , the low temperature liquid gas does not leak outside the tank, no disaster occurs, and even if the nitrogen gas diffuses, it does not affect the surroundings, and during this time the low temperature liquid inside the inner tank can be pumped out and the low temperature liquid produced inside the space can be recovered. It has excellent effects.

In addition, since the recovered hot water effluent low-temperature liquid does not contain dirt or dust, the recovered low-temperature liquid can be used as is, which is an excellent effect.

[Brief explanation of drawings]

The drawings are explanatory diagrams of one embodiment of the present invention, with FIG. 1 being a general sectional view and FIG. 2 being a partial sectional view of a nozzle pipe. 4... Outer tank, 6... Cold insulation material, 12...
Space, 10...Inner tank, 3...Foundation,
1...Tank, 19...Nozzle pipe, 21
...Liquid nitrogen source, 31...Control device, 29...
Detector, 23...Pump Applicant Kawasaki Heavy Industries Co., Ltd. Agent Tomi 1) Haru Yuki

Claims (1)

[Claims] In a low-temperature double-shell tank structure in which a cold insulating material is attached to the inner surface of the outer tank, an inner tank is provided with a space between the cold insulating material and the inner tank, and these are installed on a foundation, there is a space between the inner tanks such as the side cold insulating material. A low-temperature duplex, characterized in that a nozzle pipe is arranged around the lower part of the space, and the nozzle pipe is connected to a liquid nitrogen source via a pump connected to a leakage detection control device. Shell tank structure.