JP5339203B2 - Low temperature fluid storage facility in bedrock - Google Patents

Description

  The present invention relates to a facility for storing a low-temperature fluid such as LPG, LNG, or DME in a storage tank provided in a rock mass.

This type of facility excavates a large-scale cavity in a stable deep underground rock, and makes the cavity function as a tank (storage tank) to make LPG (liquefied petroleum gas), LNG (liquefied natural gas), DME (dimethyl ether) These are used to store low-temperature liquefied gases such as other types, or other low-temperature liquids or gases, and are roughly classified into "freezing" and "membrane-type" types depending on the lining structure provided on the inner surface of the cavity. .
The “freezing type” ensures airtightness and liquid-tightness by a stable freezing region that is naturally formed by freezing of the rock around the cavity, and the “membrane type” is airtight by the membrane material provided on the inner surface of the cavity. The former can be applied to the storage of LPG (−42 ° C.) and DME (−25 ° C.) having a relatively high boiling point. For storage at (-162 ° C), the latter is considered to be more advantageous in terms of structural stability and reliability of the storage tank.

However, in order to ensure sufficient structural stability and reliability even in membrane-type storage tanks, it is necessary to eliminate the adverse effects caused by freezing and expansion of surrounding rock mass and the groundwater pressure received from surrounding rock mass. Therefore, a membrane type rock storage tank having a structure shown in Patent Document 1 has been proposed.
This is because the lining is composed of spray concrete, frame concrete, cold insulation, membrane material, and a heating pipe network is embedded in the frame concrete to circulate a heating medium such as hot water or brine, and A drainage pipe network is buried in shotcrete to collect and drain groundwater from the surrounding rock mass.

  According to this, it is possible to prevent the surrounding rock mass from freezing by heating the concrete frame and the surrounding rock mass outside it by the heated pipeline network, and to prevent the surrounding water from being adversely affected by freezing and expansion. By collecting and draining water through the drainage pipe network, excessive groundwater pressure can be prevented from acting on the lining, thereby preventing adverse effects, and thus the structural stability and reliability of the membrane type rock storage tank It can be sufficiently secured, and is expected to spread in the future.

JP 2008-230849 A

As described above, the membrane-type rock storage tank having the structure shown in Patent Document 1 is sufficiently effective, but leaves room for improvement in the following points.
In other words, in the above structure, groundwater is drained from the surroundings of the storage tank, so there is room for lowering of the groundwater level depending on the site conditions, which has an adverse effect on the surrounding groundwater environment, and further ground subsidence. There are also concerns that arise. Therefore, a storage tank with the above structure cannot be installed in the basement of an area where there is a facility or structure where groundwater level drop or ground subsidence is not allowed, and conversely, such a facility or structure is located above the storage tank with the above structure. Since things should not be installed, the location requirements become extremely strict.
In particular, when installing this type of rock storage tank, it is also necessary to install various related facilities on the surface part directly above, but it is expected that these related facilities will be adversely affected by groundwater level drop and land subsidence. In some cases, it must be installed in a remote location where the adverse effects are not affected, and it is extremely inconvenient and unreasonable to operate the facility.

In addition, since it is not always easy to secure a site for installing this type of rock storage tank, there are many requests to make effective use of the underground of various existing facilities, but this is not realistic at this time. .
That is, if this kind of rock storage tank is installed in the basement of an existing LNG base that is already in operation, for example, it will not be necessary to secure a new site, and Coordination is also possible and is considered effective, but in order to be able to do so, ground subsidence is surely prevented in order to avoid adverse effects on existing ground facilities by installing rock storage tanks It is necessary, but at present, it is difficult to dispel the concerns about land subsidence.

  In view of the above, in order to popularize the rock storage tank with the above structure, it is necessary to prevent groundwater level drop and ground subsidence reliably in order to promote its use. Is needed.

  The present invention has been made in view of the above circumstances, and forms a lining made of sprayed concrete, reinforced concrete, cold insulation, and membrane material on the surface of a cavity excavated in the rock, and groundwater from the surrounding rock in the sprayed concrete. Membrane-type bedrock that embeds a drainage pipe network for collecting and draining water, and embeds a heating pipe network for circulating a heating medium such as warm water and brine in the concrete frame A storage tank is provided, and ground water is collected from the surrounding rock mass by the drainage pipeline network while maintaining at least the outer peripheral portion of the concrete and the outer sprayed concrete and the surrounding rock mass above the freezing temperature by the heated pipeline network. The rock storage tank is configured to store a cryogenic fluid in the rock storage tank while draining water, and water is supplied to the ground above the rock storage tank from the ground surface. Characterized by comprising comprises a groundwater recharge facility for artificially recharge groundwater with.

  As groundwater recharge equipment in the present invention, one using a plurality of water injection wells arranged above and to the side of the rock storage tank, or a water supply shaft and water injection tunnel provided above the rock storage tank and from the water injection tunnel to the surroundings It is preferable to have a large number of water injection holes formed, all of which are equipped with water supply equipment for supplying water to the water injection wells or water supply shafts, and clog the water injection wells or water injection holes as necessary. It is preferable to provide a water quality adjusting device for preventing this.

  According to the present invention, by installing the groundwater recharge facility on the ground above the rock storage tank, the groundwater level is prevented from lowering due to the rock storage tank collecting and draining the surrounding groundwater through the drainage pipe network, Therefore, the surrounding groundwater environment will not be adversely affected, and land subsidence due to lowering of the groundwater level will not occur. Therefore, the location conditions of the rock storage tank can be greatly relaxed. For example, the existing LNG base A bedrock storage tank can be installed underground.

It is a schematic diagram showing an embodiment of a cryogenic fluid storage facility in rock according to the present invention. It is a schematic diagram which shows other embodiment of the cryogenic fluid storage facility in the rock mass of this invention.

  FIG. 1 shows an embodiment of a cryogenic fluid storage facility in a rock according to the present invention. This is to prevent lowering of the groundwater level and ground subsidence resulting from it when the membrane type rock storage tank 1 having the above-described structure is installed, and a groundwater recharge facility 10 is installed for that purpose. is there.

In the present embodiment, the rock storage tank 1 is similar to that shown in Patent Document 1, and the surface of a tunnel-shaped cavity excavated in the rock is sprayed concrete 2 (in the illustrated example, primary sprayed concrete 2a and secondary sprayed concrete 2b). 2 layers), reinforced concrete 3, cold insulation 4 and membrane material 5 are formed, and groundwater is collected from the surrounding bedrock in shotcrete 2 (in the example shown, secondary shotcrete 2b). A drain pipe network 6 for draining is embedded, and a heating pipe network 7 for circulating a heating medium such as warm water or brine is embedded in the concrete frame 3.
In this rock storage tank 1, the concrete 3 and the surrounding surrounding rock mass are heated by the heating pipe network 7 to prevent the surrounding rock mass from freezing, and it is not adversely affected by freezing and expansion. The groundwater is collected by the drainage pipe network 6 and drained through the bottom drainage groove 8, thereby preventing excessive groundwater pressure from acting on the lining and preventing the adverse effects thereof. Sufficient stability and reliability can be secured.

  However, as described above, in the rock storage tank 1 having such a structure, groundwater is collected and drained from the surrounding rock as shown by the arrows in the figure, so that the groundwater level decreases as shown by the broken line in the figure. In this embodiment, by installing the groundwater recharge facility 10, the groundwater level is lowered and the ground subsidence caused by the groundwater recharge facility 10 is assumed. Is surely prevented.

The groundwater recharge facility 10 according to the present embodiment has a water supply facility 12 in which a large number of water injection wells 11 are arranged at predetermined intervals in the axial direction of the bedrock storage tank 1 above and to the sides of the bedrock storage tank 1. By supplying water to each water injection well 11, water is injected through the water injection wells 11 and into the ground above and to the side of the rock reservoir 1.
Thereby, the water supplied from each water injection well 11 flows toward the bedrock reservoir 1 as shown in the figure, and the decrease in the groundwater level due to the drainage from the surrounding bedrock of the bedrock reservoir 1 is compensated. The groundwater level can be kept high as shown by the solid line.

  The water supply facility 12 of the present embodiment is basically configured to supply supply water from the water supply tank 13 installed on the ground surface to each water injection well 11 through the water supply pipe 14. It may be due to natural flow from the supply tank 13, or may be pumped by a pump and injected under pressure if necessary. In some cases, the water supply tank 13 may be omitted, and an appropriate water source may be supplied to each water injection well 11. It may be supplied directly.

It is preferable to use industrial water, sewage treated water, and rainwater as the supply water. If possible depending on the location, river water or lake water can be used, or groundwater collected from the bedrock storage tank 1 (drainage pipe) It is conceivable to use groundwater collected by the net 6 and drained to the surface, but depending on the quality of the supplied water, the water injection well 11 may be clogged. A water quality adjusting device 15 is provided, and the water quality adjusting device 15 adjusts the water quality to a level that does not cause clogging by the water quality adjusting device 15 in front of the water supply tank 13, thereby providing stable groundwater recharge over a long period of time. Is possible.
The treatment process by the water quality adjusting device 15 may be appropriately set according to the quality of raw water and the quality of water required for the supply water, but it is fundamental to remove a large suspension to a fine suspension by a multistage treatment device. In the case where there is a concern about the growth of microorganisms or the like, a chlorine-based chemical addition device may be added, and when heavy metal ions cannot be ignored, a forced oxidation device or a filtration device may be added. Of course, if the raw water is sufficiently clean and there is no concern about clogging, the water quality adjusting device 15 may be sufficiently simple or may be omitted.

By installing the groundwater recharge facility 10 described above, the groundwater level is prevented from being lowered when the rock storage tank 1 collects and drains the surrounding groundwater through the drainage pipe network 6, and therefore the surrounding groundwater environment. It does not adversely affect the land and does not cause land subsidence due to groundwater level drop.
Therefore, the location conditions of the above-mentioned bedrock storage tank 1 are greatly eased, and it will be installed without any trouble even in an area where the conventional bedrock storage tank 1 cannot be installed due to the concern that the groundwater level will drop or the ground will sink. And the related facilities of the bedrock storage tank 1 can be installed on the surface portion directly above it without any trouble.
For the same reason, it is possible to install the rock storage tank 1 in the lower ground of an existing facility, which is not practical in the past, for example, in the basement of the existing LNG base, and thereby the rock storage tank 1 without securing a new site. It is possible to construct a new facility, and it is possible to rationally plan and operate the entire facility by linking the existing facility with the bedrock storage tank 1 newly installed in the basement.

FIG. 2 shows another embodiment of the cryogenic fluid storage facility in the rock according to the present invention. In this structure, the groundwater recharge facility 10 is constituted by a water supply shaft 16, a water injection tunnel 17, and a number of water injection holes 18 formed from the water injection tunnel 17 toward the periphery thereof. A large number of comb teeth are provided at predetermined intervals in the axial direction of the water injection tunnel 17 and are arranged so as to cover the upper part of the rock storage tank 1 as a whole.
Also in this case, the water supplied from each water injection hole 18 is supplied from the water quality adjusting device 15 to the water supply shaft 16 and supplied from the water injection tunnel 17 to the ground above the bedrock storage tank 1 through each water injection hole 18. As shown in the figure, it flows toward the rock reservoir 1 and compensates for the decrease in groundwater level due to drainage from the surrounding rock mass of the rock reservoir 1, and the groundwater level drops as shown by the broken line Therefore, it is possible to prevent the groundwater level from lowering and ground subsidence, and it is possible to recharge the groundwater stably over a long period without clogging the water injection hole 18.

  In the present invention, it is only necessary to compensate for the groundwater level drop assumed by groundwater drainage through the drainage pipe network 6 and maintain the groundwater level after recharge to be equal to the natural groundwater level. The amount of water injected should be equal to the amount of water drained from the bedrock storage tank 1, but if necessary, the amount of water injected can be controlled so that the groundwater level after recharge is maintained at the desired water level. It is also preferable to provide the groundwater recharge facility 10 with control means for constantly monitoring the groundwater level and adjusting the amount of water injection appropriately.

DESCRIPTION OF SYMBOLS 1 Bedrock storage tank 2 Sprayed concrete 2a Primary sprayed concrete 2b Secondary sprayed concrete 3 Frame concrete 4 Cold insulation material 5 Membrane material 6 Drainage pipe network 7 Heating pipe network 8 Bottom drainage groove 10 Groundwater recharge equipment 11 Injection well 12 Water supply equipment 13 Water supply tank 14 Water supply pipe 15 Water quality adjusting device 16 Water supply shaft 17 Water injection tunnel 18 Water injection hole

Claims (4)

Drainage network for collecting groundwater from the surrounding rock mass and draining it in the sprayed concrete by forming a lining made of sprayed concrete, frame concrete, cold insulation material, membrane material on the surface of the cavity excavated in the rock mass And a membrane type rock mass storage tank in which a heating pipe network for circulating a heating medium such as hot water or brine is embedded in the concrete, and the heating pipe network While maintaining at least the outer periphery of the concrete and the sprayed concrete outside and the surrounding rock mass above the freezing temperature and collecting and draining groundwater from the surrounding rock mass by the drainage pipe network, the cryogenic fluid is supplied to the rock mass storage tank. A cryogenic fluid storage facility in the rock that is configured to store,
A cryogenic fluid storage facility in a bedrock comprising groundwater recharge equipment for artificially recharging groundwater by supplying water from the surface to the ground above the bedrock storage tank. The cryogenic fluid storage facility in rock according to claim 1,
The groundwater recharge facility comprises a plurality of water injection wells arranged above and to the side of the rock storage tank, and a water supply facility for supplying water to the water injection well, wherein the cryogenic fluid storage facility in the rock mass is characterized. The cryogenic fluid storage facility in rock according to claim 1,
The groundwater recharge equipment includes a water supply shaft and water injection tunnel provided above the low-temperature rock storage tank, a number of water injection holes formed from the water injection tunnel toward the periphery thereof, and a water supply for supplying water to the water supply shaft A rock fluid cryogenic fluid storage facility characterized by comprising equipment. A cryogenic fluid storage facility in rock according to claim 2 or 3,
The rock supply cryogenic fluid storage facility, wherein the water supply facility is provided with a water quality adjusting device for preventing clogging of the water injection well or the water injection hole.

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