JP5168960B2 - Underground cryogenic liquefied gas storage tank - Google Patents

Description

  The present invention relates to an underground low-temperature liquefied gas storage tank for storing low-temperature liquefied gases such as methane, propane, nitrogen, hydrogen, and butane.

As shown in FIG. 7 , the underground low-temperature liquefied gas storage tank for storing liquefied gas such as methane generally has a side wall portion 31 installed at the periphery of the cavity portion formed in the ground, The bottom plate 32 is installed at the bottom, and the roof 33 is installed on the side wall 31. And the side wall part 31 is an external pressure load-bearing structure for securing a ground cavity part stably, for example, the underground continuous wall 34, the side wall case 35 provided in the inner periphery, and the side wall case 35 It is comprised from the cold insulating material 36 attached to the internal peripheral surface, and the membrane 37 installed so that the internal peripheral surface of this cold insulating material 36 may be covered, These each structural member has the performance shown below. (Refer nonpatent literature 1).

(1) The underground continuous wall 34 of the external pressure load-bearing structure has an external pressure load-proof performance that supports the earth pressure and groundwater pressure of the ground and a water stop performance that restricts the inflow of groundwater and the like from the ground.
(2) The side wall housing 35 has an internal pressure load-bearing performance that supports the storage pressure that the membrane 37 receives from the liquefied gas, a performance that prevents diffusion when the liquefied gas leaks, and a ground pressure of the ground as well as the underground continuous wall 34. And it has an external pressure load resistance performance that supports the groundwater pressure.
(3) The cold insulating material 36 has an internal pressure transmission performance for transmitting the storage pressure to the side wall housing 35 as well as a heat insulation performance for blocking heat flow between the outside and the liquefied gas.
(4) The membrane 37 has a pleated corrugation for absorbing heat shrinkage and thermal expansion, and has airtight / liquidtight performance for enclosing and sealing a liquefied gas.
“LNG underground storage tank guideline JGA finger-107-02”, Japan Gas Association, revised edition issued in August 2002

  However, the above-described side wall 31 is constructed such that the underground continuous wall 34 which is an external pressure load-bearing structure, the side wall housing 35 having different performance such as the liquid storage performance, the cold insulation 36 and the membrane 37 are integrated. Therefore, for example, when the membrane 37 is damaged and the fluid in the storage tank leaks, the membrane 37 itself is damaged due to a defective portion or due to external factors such as deformation of the side wall housing 35. There was a problem that the cause of the damage could not be specified because I did not know what happened. And since the cause could not be specified, there was a problem that it took time to repair.

  Further, for example, if the groundwater passes through the side wall housing 35 made of concrete, the cold insulation 36 does not have water-stopping performance. There is a problem in that the membrane 37 may be damaged by the freezing and expansion. In other words, if any one of the performances (here, water stoppage performance) decreases, the other performances (here, heat insulation performance, liquid tightness / air tightness performance) will be chained, and many performances will be performed at once. There was a problem that would decrease.

Accordingly, the present invention has been made in view of the above-described conventional problems, and the performance required for the underground cryogenic liquefied gas storage tank is divided by the structure constituting the underground cryogenic liquefied gas storage tank. and, one of performance without affecting other performance decreases, and aims to provide an underground low-temperature liquefied gas savings tank to facilitate the abnormality cause certain damage such as To do.

In order to achieve the above object, the underground cryogenic liquefied gas storage tank of the present invention is an underground cryogenic liquefied gas storage tank constructed in the ground, and is installed so as to cover the inner wall of the cavity formed in the ground. A side wall structure that does not include a bottom plate and can directly support the earth pressure and groundwater pressure of the ground, and has a water stopping performance that prevents intrusion of groundwater, and directly on the bottom ground inside the side wall structure. Alternatively, an inner storage tank that is installed through a drainage layer and has airtightness, liquid tightness, heat insulation, and self-sustainability necessary for storing the liquefied gas is provided as an independent structure, and the inner storage tank and the side wall A space is provided between the structure and the structure (first invention).

  The underground cryogenic liquefied gas storage tank according to the present invention includes a side wall structure installed to maintain stability of a cavity formed in the ground, and an inner storage tank provided inside the side wall structure. The side wall structure bears the external pressure load bearing performance that supports the earth pressure and groundwater pressure of the ground and the water stopping performance that can limit the ingress of groundwater as much as possible, and the inner storage tank bears the liquid storage performance for storing liquefied gas. That is, since the side wall structure and the inner storage tank which are independent from each other bear different performances, even if one of the performances is lowered, the other performance is not affected. Therefore, according to the present invention, it is possible to improve the safety of the underground low-temperature liquefied gas storage tank, and it is possible to quickly and surely maintain and repair as a response when one performance deteriorates.

  And, when a problem occurs in the side wall structure or the inner storage tank, the performance of the structure having the defective part (here, the side wall structure or the inner storage tank) is deteriorated, so that the structure having the defective part can be easily identified. At the same time, it becomes easy to identify the cause of the malfunction. For example, when the liquefied gas leaks, the liquid storage performance is deteriorated, so that it can be specified that there is a cause of the malfunction in the inner storage tank. If the sidewall structure around the periphery of the cavity cannot maintain the stability of the cavity, it can be determined that there is a cause for the failure in the sidewall structure because the external pressure load-bearing performance has deteriorated. Take repair measures to repair and reinforce the sidewall structure so that it can be maintained. During this time, the liquefied gas storage tank can play its original role without deteriorating the liquid storage performance. As described above, even if a problem occurs in the side portion of the underground cryogenic liquefied gas storage tank, it is easy to identify the problem location and to perform accurate repair.

  In addition, the side wall structure can be built independently by the strength required for external pressure load-bearing performance, and the inner storage tank can be constructed independently by the strength required for liquid storage performance. Therefore, it is possible to reduce the amount of materials used such as concrete and steel for low temperature.

According to a second invention, in the first invention, the inner storage tank includes an inner tank for storing the liquefied gas, a cold insulating material attached so as to cover an outer periphery of the inner tank, and an outer periphery of the cold insulating material. It is comprised from the outer tank installed so that it may cover.
According to the underground low-temperature liquefied gas storage tank according to the present invention, the inner storage tank includes an inner tank that stores the liquefied gas, a cold insulating material that blocks heat from entering and exiting, and an outer tank that prevents diffusion when the liquefied gas leaks. The inner tank bears the internal pressure load-bearing performance that supports the storage pressure of liquefied gas and the airtight / liquidtight performance that seals liquefied gas, and the cold insulation material blocks the flow of heat between the outside and the liquefied gas. The outer tank bears the anti-diffusion performance that mitigates the effects of cold and prevents diffusion when the liquefied gas leaks out. That is, the inner tank, the cold insulating material, and the outer tank, which are independent from each other, bear different performances and integrate these performances to constitute the liquid storage performance.

  According to the underground low-temperature liquefied gas storage tank and the design method of the present invention, the external pressure load-carrying performance that supports the earth pressure and groundwater pressure of the ground, and the liquid storage performance that contains the liquefied gas and stores the fluid are independent from each other. Since it does not affect the performance of one of them when the performance of one of them declines, it ensures the high safety of the underground cryogenic liquefied gas storage tank and greatly increases its reliability Can be improved. In addition, when the external pressure load-bearing performance and liquid storage performance are reduced, the shape of the side wall structure, leakage of liquefied gas, etc. are generated, respectively, and it is easy to find. Since repair may be performed, it is possible to reliably repair in a short period of time even if a failure occurs, and the maintenance repairability of the underground low-temperature liquefied gas storage tank is remarkably improved.

  Hereinafter, a preferred embodiment of an underground cryogenic liquefied gas storage tank according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic structural diagram of an underground cryogenic liquefied gas storage tank according to the present invention.
As shown in FIG. 1, an underground low-temperature liquefied gas storage tank 1 for storing a liquefied gas such as methane is installed so as to cover an inner wall of a cavity 11 formed in the ground 2, and earth pressure and groundwater pressure of the ground 2. The side wall structure 3 having a water-stopping property that can limit the ingress of groundwater as much as possible, and the airtight / liquid tightness that is provided inside the side wall structure 3 and is necessary for storing the liquefied gas The side wall structure 3 and the inner storage tank 6 are provided as structures independent of each other.

  The side wall structure 3 is generally constructed by a concrete continuous wall made of concrete, and supports the external pressure load resistance that supports the earth pressure and groundwater pressure of the ground 2 and the water stop performance that prevents the inflow of groundwater from the ground 2 as much as possible. And is constructed with a predetermined thickness up to a predetermined depth determined by design or the like.

  The inner storage tank 6 is constructed by providing the drainage layer 4 on the bottom ground of the hollow portion 11 as necessary, and has a liquid storage performance of containing the liquefied gas and storing the fluid. The inner storage tank 6 is attached so as to seal the liquefied gas and cover the inner tank 7 for supporting the storage pressure of the liquefied gas, and the bottom plate portion 7a and the side part 7b of the inner tank 7 from the outside. Is installed so as to cover the cold insulation material 8 from the outside, and when the liquefied gas leaks from the inner tank 7, the influence of the cold heat is alleviated and diffused. It is comprised from the outer tank 9 for preventing. The inner storage tank 6 is provided inside the side wall structure 3 with a predetermined interval L, and a space 5 is formed between the side wall structure 3 and the inner storage tank 6. In the present embodiment, the space 5 is provided between the side wall structure 3 and the inner storage tank 6 so that a person can enter. However, the space 5 is not limited to this size. It is sufficient that there is a gap that does not contact the inner storage tank 6. For example, the amount of deformation when a predetermined earth water pressure is applied to the side wall structure 3 by design or the like is calculated, and the gap larger than this amount of deformation is calculated. I just need it.

  The inner tank 7 is made of, for example, a low-temperature steel material such as a 9% Ni steel plate having elasticity at low temperatures, can be self-supporting, has airtight / liquidtight performance for sealing liquefied gas, and is stored in a pressurized state. It has an internal pressure load bearing performance that supports the stored pressure of the liquefied gas.

  The cold insulating material 8 is made of a cold insulating material such as polyurethane foam or pearlite, and has a heat insulating performance that blocks heat from entering and leaving between the outside and the liquefied gas.

  The outer tub 9 is made of reinforced concrete or prestressed concrete, and has a performance as a breakwater that relieves the influence of cold and prevents diffusion when liquefied gas leaks from the inner tub 7.

  The drainage layer 4 is provided as necessary. Although not shown, the drainage layer 4 is used to collect a large amount of crushed stones, a water collecting pipe for collecting water, and to collect and drain the collected water to the ground. It consists of a pump. The groundwater or the like that flows into the drainage layer 4 from the surrounding ground 2 and flows under the side wall structure 3 is collected in one place by a collecting pipe and drained to the ground by a pump. Although not shown, a pump for draining rainwater and the like in the space 5, a water detection sensor for detecting storage of rainwater, and a gas detection sensor for detecting storage of liquefied gas are also installed in the space 5. .

Next, the construction method of the underground low-temperature liquefied gas storage tank 1 will be described according to the construction procedure.
2-6 is a figure which shows the construction procedure of the underground type | mold low temperature liquefied gas storage tank 1 which concerns on this invention.

First, as shown in FIG. 2, a side wall structure 3a composed of a continuous underground wall is formed by excavating the ground 2 into a cylindrical shape to a predetermined depth, discharging excavated soil, and filling the excavated portion with concrete. Build up.
And after the desired intensity | strength of the side wall structure 3a expresses, as shown in FIG. 3, the earth and sand inside the inner peripheral surface is excavated, and the cavity part 11 which the upper part opened is constructed | assembled.

  Next, gravels, pebbles, crushed stones and the like are laid on the bottom of the cavity 11, and a drainage pipe and a pump are installed to construct the drainage layer 4.

  Next, as shown in FIG. 4, the outer tub 9 is constructed inwardly with a predetermined distance L from the inner peripheral surface of the side wall structure 3a. The outer tub 9 is constructed in the following procedure. First, a bottom plate reinforcing bar (not shown) is assembled on the drainage layer 4, and a disc-shaped bottom plate portion 9a is constructed by placing concrete. Next, after the desired strength of the bottom plate portion 9a is expressed, Side reinforcing bars (not shown) are assembled to the outer peripheral portion of the bottom plate portion 9a, and concrete side portions 9b are constructed by placing concrete. In addition, when the outer tub 9 is made of prestressed concrete, a tension material such as PC steel is installed inside the assembled bottom plate reinforcing bars and side reinforcing bars, and the concrete is cast to develop the strength of the concrete. After that, strain the tension material.

  Next, as shown in FIG. 5, the inner tank 7 is constructed. The inner tank 7 is constructed in the following procedure. First, the disc-shaped bottom plate portion 7a is constructed on the cold insulating material 8a attached to the bottom plate portion 9a of the outer tank 9, and the inner tank side wall portion 7b is constructed on the outer peripheral portion of the bottom plate portion 7a. Then, the roof portion 7c is constructed so as to cover the upper opening surrounded by the bottom plate portion 7a and the side portion 7b. When the inner tank 7 is constructed in this way, the cold insulating material 8b is filled in the gap between the inner tank 7b and the outer tank 9b.

  Finally, as shown in FIG. 6, the underground cryogenic liquefied gas storage tank 1 is constructed by extending the sidewall structure 3 b on the sidewall structure 3 a and constructing a bank around the sidewall structure 3 b. The

  According to the underground low-temperature liquefied gas storage tank 1 according to the present invention constructed as described above, the side wall structure 3 installed so as to cover the inner wall of the cavity portion 11 formed in the ground 2, and the side wall structure The side wall structure 3 bears an external pressure load-bearing performance, and the inner tank 6 bears a liquid storage performance. That is, since the side wall structure 3 and the inner storage tank 6 that are independent from each other bear different performances, even if one of the performances decreases, the other performance is not affected. Therefore, the safety of the underground low-temperature liquefied gas storage tank 1 can be improved. Moreover, since each performance is shared by structures independent from each other, it is handled and simplified individually in the designing process and the building process, thereby greatly improving the efficiency and economy in the process.

  And when a malfunction occurs in the side wall structure 3 and the inner storage tank 6, only the performance of the structure having the malfunctioning portion (here, the external pressure load resistance performance of the side wall structure 3 or the liquid storage performance of the inner storage tank 6) is deteriorated. In addition, it is easy to identify a structure having a defect location and to identify the cause of the defect. For example, when the liquefied gas leaks, the liquid storage performance is deteriorated, so that it can be specified that the inner storage tank 6 has a problem. As described above, even if a problem occurs in the side portion of the underground low-temperature liquefied gas storage tank 1, it becomes easy to identify the problem location and correct it.

  Further, since the side wall structure 3 can be constructed according to the strength required for external pressure load-bearing performance and the inner storage tank 6 can be constructed according to the strength required for liquid storage performance, the side wall structure 3 and the inner storage tank 6 can be rationally designed. It becomes possible to reduce the amount of materials such as steel and concrete.

  By providing the space 5 between the side wall structure 3 and the inner storage tank 6, the side wall structure 3 is damaged and the water stoppage is lowered, so that groundwater flows into the space 5 or the inner storage tank 6 is damaged. When the liquid storage performance deteriorates and the liquefied gas flows into the space 5, since the groundwater and the liquefied gas are stored in the space 5, the above-described water detection sensor and gas detection sensor can quickly detect a leak. It is possible that the person enters the space 5 to visually check the malfunction state. In addition, since a person, a machine, or the like can enter the space 5 and repair the damaged portion, the repair can be performed in a short time and surely.

It is a schematic structure figure of an underground type low-temperature liquefied gas storage tank concerning the present invention. It is a figure which shows the construction procedure of the underground type | mold low-temperature liquefied gas storage tank which concerns on this invention. It is a figure which shows the construction procedure of the underground type | mold low-temperature liquefied gas storage tank which concerns on this invention. It is a figure which shows the construction procedure of the underground type | mold low-temperature liquefied gas storage tank which concerns on this invention. It is a figure which shows the construction procedure of the underground type | mold low-temperature liquefied gas storage tank which concerns on this invention. It is a figure which shows the construction procedure of the underground type | mold low-temperature liquefied gas storage tank which concerns on this invention. It is a schematic structure figure of the conventional underground type low-temperature liquefied gas storage tank.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subsurface type cryogenic liquefied gas storage tank 2 Ground 3 Side wall structure 4 Drainage layer 5 Space 6 Inner storage tank 7 Inner tank 8 Cold insulation material 9 Outer tank 11 Cavity part 31 Side wall part 32 Bottom plate 33 Roof 34 Continuous underground wall 35 Side wall frame 36 Cold insulation Material 37 Membrane L Predetermined spacing

Claims (2)

An underground cryogenic liquefied gas storage tank built in the ground,
Side wall structure without bottom plate that is installed so as to cover the inner wall of the cavity formed in the ground, and can support the soil pressure and groundwater pressure of the ground independently and has a waterproof performance to prevent intrusion of groundwater. Things,
An inner storage tank that is installed directly or via a drainage layer on the inner bottom ground of the side wall structure and has airtightness, liquid tightness, heat insulation, and self-sustainability necessary for storing the liquefied gas. Provided as an independent structure ,
An underground cryogenic liquefied gas storage tank characterized in that a space is provided between the inner storage tank and the side wall structure . The inner storage tank is
An inner tank for storing the liquefied gas;
A cold insulator attached to cover the outer periphery of the inner tank;
The underground low-temperature liquefied gas storage tank according to claim 1, comprising an outer tank installed so as to cover an outer periphery of the cold insulation material.

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