JP2013119931A - Underground freezing control type storage facility of low-temperature liquefied gas - Google Patents

Abstract

An object of the present invention is to provide an underground freezing control type storage facility that can economically maintain and maintain a frozen ground around an underground storage tank for a long period of time.
A storage tank for cold and liquefied gas LG constructed by vertically excavating a plurality of points Q1, Q2, Q3, Q4,... ,... At a plurality of positions along a boundary line R between the heating medium pipes 10U vertically drilled at a plurality of positions along the annular line U and adjacent points Q1, Q2, Q3, Q4,. A heating medium pipe 10R drilled vertically and a heating medium circulation device 15 that circulates the heating medium T in each heating medium pipe 10U, 10R are provided, and the freezing around each storage tank 2 is controlled by the circulation of the heating medium T. To do. Preferably, the heat medium circulation device 15 includes control means 16U and 16R for independently controlling circulation of the heat medium T with respect to the heat medium tubes 10U and 10R. Further, the plurality of points Q1, Q2, Q3, Q4,... Can be the respective vertex positions of the polygon on the ground surface E.
[Selection] Figure 1

Description

  The present invention relates to a cryogenic liquefied gas underground freezing controlled storage facility, and more particularly to a facility for storing cryogenic liquefied gas underground while controlling freezing of the ground / rock (hereinafter sometimes referred to as the ground).

  Gaseous fuels (such as natural gas and petroleum gas that are gaseous at normal temperature and pressure) that are used as energy sources for thermal power generation, etc., are disadvantageous for transportation and storage compared to solid and liquid fuels (coal, oil, etc.). However, it can be transported and stored as liquefied gas (hereinafter referred to as low temperature liquefied gas) by pressurization and cooling. In Japan, low-temperature liquefied gases such as LNG and LPG are imported from the country of origin and stored in a domestic storage facility (acceptance base). ing. Conventionally, metal double-shell type ground tanks have been used as storage facilities for low-temperature liquefied gas, but liquefied gas leakage countermeasures are indispensable for ground tanks, and the outflow range at the time of leakage is localized around the tank. A relatively large site area is required to construct a liquid bank (see Non-Patent Document 1). In contrast, underground storage facilities have been developed in which most or all of the facilities are buried underground to reduce the risk of liquefied gas flowing out to the ground (see Patent Documents 1 to 3).

  For example, in Patent Documents 1 and 2, as shown in FIG. 4 (A), the inside of the underground continuous wall 21 constructed in a cylindrical shape is excavated to the deepest part, and a concrete side wall 22 and a bottom wall 23 are formed inside thereof. An underground storage tank 20 is disclosed in which a housing (bottomed tank body) is formed by casting and the opening of the housing is covered with a dome-shaped roof 24. A steel material layer called a membrane and a heat insulating material layer 26 (see FIG. 4B) are laid on the entire inner surface of the housing (the side wall 22 and the bottom wall 23), and the low temperature liquefied gas LG is introduced from the receiving line 4 and stored. To do. The stored liquefied gas LG can be appropriately discharged from the discharge line 5 via the vaporizer 5a. The underground storage tank 20 in the illustrated example has a skeleton under the ground surface and only the dome-shaped roof 24 can be seen from the ground, so that the surrounding landscape is not impaired and the liquefied gas LG is less likely to leak to the ground. Since there is no need for such a site, there is an advantage that the use efficiency of the site is high. Further, since the tank 20 in the illustrated example may cause the liquefied gas LG to leak into the atmosphere if the roof 24 is damaged, the dome-shaped roof 24 is buried in the ground as in Patent Document 3 to reduce the risk of leakage. A more conserved underground tank has also been proposed.

  The underground storage tank 20 for storing the cryogenic liquefied gas LG (for example, LNG at −162 ° C.) is frozen, although the surrounding ground (groundwater) is frozen by cold heat, so that the liquid and air tightness of the tank is improved. Because of the frost heaving (the phenomenon that the ground rises and deforms due to the formation of an ice layer) due to the expansion of the surface, there is a risk of applying large pressure (freezing earth pressure) to the tank housing, so the surrounding freezing is artificially done for safety Need to control. For example, as shown in FIG. 4B, side heaters 27 and bottom heaters 28 (for example, pipes having a diameter of about 10 cm arranged at intervals of about 4 m) are laid along the outer surface of the underground tank 20 to heat for heating. The medium (for example, warm water or brine using steam or the like as a heat source) is circulated, and the progress and expansion of the frozen ground F are stopped by thermally balancing the cold heat of the liquefied gas LG and the heat of the heaters 27 and 28 (non- Patent Document 2). On the other hand, in order to suppress the vaporization and transpiration of the liquefied gas LP in the tank 20, it is effective to make the frozen ground F thick enough to prevent natural heat input from the surroundings. Control to be thick. In the illustrated example, the heater 28 is disposed in the ground. However, a heating medium is supplied to a method in which a hot water pipe or the like is embedded in the concrete of the bottom wall 23 or a gravel layer laid below the bottom wall 23. It can also be a method or the like.

JP 2000-130698 A JP 2002-004627 A Japanese Patent Laid-Open No. 4-312297

Japan Energy Academic Natural Gas Division, “All about Natural Gas” Corona, 106-113 (3.4 LNG receiving terminal and storage tank), issued October 3, 2008 Goto Sadao and Tanaka Masuhiro “Soil Freezing and Geotechnical Engineering 10. Soil Freezing Control around LNG Underground Tank”, Soil and Foundation, Geotechnical Society, December 2003, Vol. 86-91

  However, as shown in FIG. 4B, the method of controlling the frozen ground F by providing the side heater 27 and the bottom heater 28 around the underground tank 20 avoids the generation of a large frozen earth pressure and designs the underground storage facility. Although it is effective for facilitating the construction, it requires maintenance and management costs to keep circulating the heat medium through the heaters 27 and 28 during storage of the low-temperature liquefied gas LG. For example, recently, it has been studied to store a large amount of low-temperature liquefied gas LG for a long time using a plurality of underground tanks in order to cope with seasonal fluctuations in energy demand, etc., but as shown in FIG. In the method of controlling the frozen ground F by providing 27 and 28, the maintenance cost of the storage facility becomes enormous. When multiple underground tanks are used, it is possible to devise heat input and output by arranging adjacent tanks, and the frozen ground F is controlled by arrangement and operation of heaters 27 and 28 different from the case of one tank. Therefore, it is desired to keep the maintenance management cost as small as possible.

  Therefore, an object of the present invention is to provide an underground freezing control type storage facility that can economically maintain and maintain the frozen ground around the underground storage tank for a long period of time.

  1 and 2, the low temperature liquefied gas underground freezing controlled storage facility according to the present invention has a plurality of points Q1, Q2, Q3, Q4,... Each of which is constructed by drilling vertically) in the storage tank 2 of the cold and warm liquefied gas LG, and vertically at a plurality of positions along an annular line U (see FIG. 2) surrounding a plurality of points Q1, Q2, Q3, Q4,. The heating medium pipe 10R drilled vertically at a plurality of positions along the boundary line R (see FIG. 2) between adjacent points Q1, Q2, Q3, Q4,. The heating medium circulation device 15 that circulates the heating medium T in each of the heating medium tubes 10U and 10R is provided, and the freezing around each storage tank 2 is controlled by the circulation of the heating medium T.

  Preferably, as shown in FIG. 1, the heat medium circulating device 15 includes control means 16U and 16R for independently controlling circulation of the heat medium T to the heat medium pipes 10U and 10R. Moreover, as shown in FIG. 2 (A), a plurality of points Q1, Q2, Q3, Q4,... In this case, as shown in FIG. 2 (B), the inner heat medium pipes 10N are vertically arranged at a plurality of positions along the periphery of the inner area N surrounded by the plurality of points Q1, Q2, Q3, Q4,. The inner region N can be prevented from freezing by being pierced and circulating the heat medium T from the heat medium circulating device 15 to each inner heat medium pipe 10N.

  More preferably, as shown in FIGS. 3 (C) to 3 (D), each storage tank includes a heat medium switching device 19 for switching between a heating heat medium T and a cooling heat medium T ′ in the heat medium circulating device 15. The cooling medium T ′ is circulated through the heating medium pipes 10U and 10R before receiving the cold / liquefied liquefied gas LG to 2 to freeze around the storage tank, and after receiving the heating medium pipes 10U and 10R, the heating medium for heating. Circulate T to control freezing around the storage tank. As shown in FIGS. 3A to 3C, the heating medium pipes 10U and 10R are drilled in advance in the storage tanks 2, and the cooling heating medium is circulated through the heating medium pipes 10U and 10R. It is also possible to construct each storage tank 2 by excavating the formed frozen region F vertically.

  Desirably, as shown in FIG. 1, each storage tank 2 has a main body portion 2a having a predetermined diameter W2 extending vertically downward from a predetermined depth D underground, and a diameter W3 having a reduced diameter at the top end of the main body portion 2a. The low temperature liquefied gas LG more than the capacity | capacitance of the main-body part 2a is received in each storage tank 2 including the guiding shaft part 2b connected with E, and it stores it, keeping a liquid level in the guiding tunnel part 2b.

  A cryogenic liquefied gas underground freezing control type storage facility according to the present invention constructs an underground storage tank 2 for cold and liquefied liquefied gas LG by vertically excavating a plurality of points Q1, Q2, Q3, Q4,. A plurality of heating medium pipes 10U are vertically drilled along an annular line U surrounding a plurality of points Q1, Q2, Q3, Q4,... And between adjacent points Q1, Q2, Q3, Q4,. A plurality of heat medium pipes 10R are vertically drilled along the boundary line R, and the heat medium T is circulated from the heat medium circulation device 15 to each of the heat medium pipes 10U and 10R, thereby freezing around each storage tank 2. Since the ground is controlled, the following advantageous effects are obtained.

(A) By sharing the heat medium pipe 10R at the boundary portion R of the plurality of underground tanks 2 and simultaneously controlling the frozen ground F around the underground tanks 2 on both sides by circulation of the heat medium T of the heat medium pipe 10R, Compared to the conventional method of providing a heat medium pipe for each underground tank 2, the number of heat medium pipes 10 can be saved, and the maintenance cost of the frozen ground F can be suppressed.
(B) Further, since the boundary portion R suppresses natural heat input from the surroundings compared to the outer annular portion U surrounding the plurality of underground tanks 2, the circulation of the heat medium T to the heat medium pipe 10R on the boundary line is prevented. It can be expected that the maintenance cost of the frozen ground F can be further reduced by controlling the heating medium pipe 10U on the annular line independently and operating efficiently.
(C) Furthermore, a heating medium pipe 10N is provided along the periphery of the inner area N surrounded by the plurality of underground tanks 2, and the freezing of the inner area N is prevented by circulation of the heating medium T to the inner heating medium pipe 10N. By doing so, it becomes possible to use the underground of the area where there is a structure or natural vegetation where the influence of freezing should be avoided as a storage facility for low temperature liquefied gas.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments and examples for carrying out the present invention will be described with reference to the accompanying drawings.
These are explanatory drawings of one Example of the underground freezing control type | mold storage facility by this invention. These are horizontal sectional views of the underground freezing control type storage facility according to the present invention. These are explanatory drawings of the construction method and operation method of the underground freezing control type | mold storage facility of FIG. These are explanatory drawings of the conventional underground storage facility of low-temperature liquefied gas.

  FIG. 1 shows an embodiment of the underground freezing control type storage facility of the present invention, and FIG. 2 (A) shows a horizontal sectional view of the storage facility. The storage facility 1 in the illustrated example has four storage tanks 2 constructed by excavating each vertex position Q1, Q2, Q3, Q4 of the quadrangle on the ground surface E vertically, and four sets separated from each other. Between a heat medium pipe 10U (hereinafter, sometimes referred to as an annular heat medium pipe 10U) vertically drilled at a plurality of positions along the outer annular line U of the surface E surrounding the storage tank 2 and the adjacent storage tank 2 Heat medium pipes 10R (hereinafter also referred to as boundary heat medium pipes 10R) that are vertically drilled at a plurality of positions along the boundary line R. Each of the heat medium pipes 10U and 10R is connected to the heat medium circulation device 15, and the heating medium T (for example, hot water or brine) is sent to the heat medium pipes 10U and 10R from the circulation device 15 and returned. The thickness of the frozen ground F formed around each storage tank 2 is controlled by circulating them.

  Each of the storage tanks 2 in the illustrated example has a main body 2a having a predetermined diameter W2 extending vertically downward from a predetermined depth D below, and a guide shaft connected to the surface E by a diameter W3 having a reduced diameter at the top end of the main body 2a. Part 2b. Moreover, in each storage tank 2, the receiving line 4 which sends the low temperature liquefied gas LG which should be stored in the main-body part 2a via the guide shaft part 2b, and the discharge which sends out the low-temperature liquefied gas LG currently stored from the bottom part of the main-body part 2a A line 5 and a BOG line 6 for discharging a boil-off gas (hereinafter sometimes referred to as BOG) in which a part of the liquefied gas LG is vaporized and evaporated during storage from the guide shaft portion 2b are provided. After laying a membrane (steel material layer and heat insulation material layer) 26 inside each storage tank 2 (see FIG. 4B), a low-temperature liquefied gas LG having a liquid volume larger than the volume of the main body 2a is received from the receiving line 4. The main body 2a is filled with the liquefied gas LG, and a part of the liquefied gas LG overflows into the guide shaft portion 2b, and the liquefied gas is stored in each storage tank 2 while keeping the liquid level in the guide shaft portion 2b. Store LG. If necessary, it is also effective to provide lateral shafts that interconnect the four storage tanks 2 in order to balance the storage tanks 2.

  By reducing the diameter W3 of the guide shaft portion 2b as compared to the diameter W2 of the main body portion 2a of the storage tank 2 and forming a liquid level in the guide shaft portion 2b as in the illustrated example, the inside of the main body portion 2a As compared with the case where the liquid level is formed, the evaporation area and evaporation rate of the liquefied gas LG can be suppressed to be small, and the amount of BOG generated during storage in the storage tank 2 can be reduced. Further, by connecting the guide shaft portion 2b to the top end of the main body portion 2a, the whole main body portion 2a is filled with the liquefied gas LG when receiving the liquefied gas LG so that no gas phase portion such as an air pocket remains. be able to. Desirably, the top surface of the main body 2a is formed in a hemispherical shape or a conical shape as in the illustrated example, and when the liquefied gas LG is received, all of the residual gas is sent out to the tunnel portion 2b by the rise of the liquid level in the main body 2a. Like that.

  The annular heat medium pipe 10U of the illustrated example has small diameters drilled vertically downward from the ground surface E at a plurality of portions with a predetermined interval GU along the outer annular line U surrounding the main body 2a of the storage tank 2 with a gap SU. A shaft, for example, a boring hole having a diameter of about 10 cm can be used. As shown in FIG. 2A, the heating medium T is circulated from the heating medium circulating device 15 to maintain each heating medium tube 10U at a non-freezing temperature (0 ° C. or higher), and a plurality of annular heating medium tubes 10U. Are thermally coupled to form an annular wall having a non-freezing temperature surrounding the four storage tanks 2, thereby preventing the frozen ground F from expanding beyond the outer annular line U. 1 indicates an ambient temperature distribution curve of the storage tank 2. As can be seen from the curve C, the inside of the tank 2 for storing the liquefied gas LG is at a low temperature (for example, −162 ° C. for LNG). The temperature rises rapidly at the side wall (membrane and heat insulating material layer) of the tank 2, and the outside of the tank 2 shows a temperature gradient that gradually rises toward the outer annular line U at the non-freezing temperature.

  In FIG. 2A, the mutual interval GU of the annular heat medium pipes 10U is a non-freezing temperature surrounding the four storage tanks 2 when the heat medium pipes 10U are thermally coupled to each other, for example, when the heat medium T is circulated. Using an analysis method such as excavation analysis, heat conduction analysis, thermal stress analysis, etc., so that the annular wall is formed, and the stability of the ground is not impaired in consideration of ground strength, initial ground pressure, etc. Can be designed. The gradient of the temperature distribution curve C between the storage tank 2 and the heat transfer pipe 10U (see FIG. 1) changes according to the gap SU between the two, but by selecting an appropriate mutual interval GU according to the gap SU. The thickness of the frozen ground F along the annular line U can be controlled uniformly. It is also possible to adjust the flow rate, temperature, etc. of the heat medium T to be circulated for each heat medium pipe 10U.

  On the other hand, the boundary heat transfer medium pipe 10R in the illustrated example is a vertical shaft drilled vertically downward from the ground surface E at a plurality of portions with a predetermined interval GR along an intermediate boundary line R separated from the adjacent storage tank 2 by a gap SR. It can be set as the boring hole similar to the annular heat medium pipe | tube 10U mentioned above. For example, as shown in FIG. 2 (A), the boundary heat medium pipe 10R is drilled at the same interval GR (= interval GU) as the outer annular line U, and heat for heating is supplied from the heat medium circulation device 15 to each heat medium pipe 10R. By circulating the medium T and maintaining it at a non-freezing temperature (for example, 0 ° C.), the adjacent heat medium pipes 10R are thermally coupled to form a non-freezing temperature annular wall extending along the boundary line R. The thickness of the frozen ground F at the boundary between the four storage tanks 2 can be controlled to the same extent as the outer annular line U. As shown in the illustrated example, the heat medium pipes 10R are arranged in a row along the boundary line R of the storage tank 2, and the frozen ground F on both sides is simultaneously controlled by the heat medium pipes 10R. Compared with the conventional method (refer FIG. 4 (B)) which arrange | positions a medium pipe, the installation number of the heat medium pipe | tube 10R can be saved, and the maintenance management cost of the frozen ground F can be suppressed.

  Moreover, the thickness of the frozen ground F in the inner boundary line R surrounded by the plurality of storage tanks 2 is not necessarily the same as the frozen ground F of the outer annular line U surrounding the plurality of storage tanks 2 as in the illustrated example. In some cases. The outer annular line U has no upper limit on the thickness of the frozen ground F, and the frozen earth pressure acting on the tank 2 increases as the thickness increases. For example, when the gap SR between the storage tank 2 and the boundary heat medium pipe 10R is narrow, the entire case may be covered with the frozen ground F. In such a case, considering the ground strength, initial ground pressure, etc., the boundary heat medium pipe 10R is set to a gap GR (> gap GU) larger than the outer annular line U within a range where the stability of the ground is not impaired. It is possible to control so that the freezing of the frozen ground F proceeds unnecessarily due to the circulation of the heating medium T to the heat medium pipe 10R and secondary freezing is not generated. By increasing the interval GR between the boundary heat medium pipes 10R, the number of installed heat medium pipes 10R can be saved, and the maintenance cost of the frozen ground F can be further suppressed.

  If necessary, as shown in FIG. 2 (B), the inner heat is applied vertically downward from the ground surface E to a plurality of positions at predetermined intervals GN along the periphery of the inner area N surrounded by the plurality of storage tanks 2. The medium pipe 10N is vertically drilled, and freezing into the inner region N can be prevented by circulating the heat medium T from the heat medium circulation device 15 to each inner heat medium pipe 10N. It is necessary to construct various facility structures on the surface E of the storage facility 1, and there may be natural ecosystems to be protected. For example, in the illustrated example, when the facility structure is provided in the inner area N surrounded by the storage tank 2, storage of the facility structure is prevented by preventing freezing of the inner side U by circulation of the heat medium T from the circulation device 15. The influence of the liquefied gas LG can be avoided. Further, like the inner area N in the illustrated example, the inner heat transfer pipe 10N is drilled so as to surround the natural ecosystem to be protected, thereby preventing the expansion of the frozen area. Can be used as the storage facility 1 for the low-temperature liquefied gas LG.

  Furthermore, since the inner boundary line R surrounded by the plurality of storage tanks 2 suppresses natural heat input from the surroundings compared to the outer annular line U, the circulation of the heat medium T to the boundary heat medium pipe 10R is circular. It can be expected that the maintenance cost of the frozen ground F can be further reduced by controlling the heat medium pipe 10U independently and operating efficiently. The illustrated heat medium circulation device 15 includes circulation control means 16U and 16R that separately control the circulation of the heat medium T to the annular heat medium pipe 10U and the circulation of the heat medium T to the boundary heat medium pipe 10R. . While cold heat flows from the main body 2 on one side into the annular line U, cold heat flows from the main body 2 on both sides into the boundary line R. Therefore, circulation of the heat medium T to the heat medium tubes 10U and 10R is performed. By dividing, the frozen ground F around each storage tank 2 can be controlled rationally and efficiently. For example, the flow rate or temperature of the heat medium T circulated through the boundary heat medium pipe 10R is increased as compared with the heat medium T circulated through the annular heat medium pipe 10U. In this way, by independently controlling the circulation of the heat medium T for each of the heat medium pipes 10U and 10R, it can be expected that the maintenance cost of the frozen ground F is further suppressed.

  Thus, the provision of the “underground freezing control type storage facility capable of economically maintaining and managing the frozen ground around the underground storage tank” for a long time, which is the object of the present invention, can be achieved.

  1 and 2, only the annular heat transfer medium pipe 10U and the boundary heat transfer medium pipe 10R arranged at the side of the underground storage tank 2 are shown, but if necessary, the same as in the case of FIG. 4B. In addition, the thickness of the frozen ground F can be controlled by laying a heat transfer pipe at the bottom of the storage tank 2. For example, the heat transfer medium pipe is installed at the bottom of the storage tank 2 by overdrilling in internal excavation, free boring (curved boring) or the like. Further, in the illustrated example, a plurality of storage tanks 2 are arranged at the respective quadrature vertex positions Q1, Q2, Q3, and Q4 on the ground surface E, but the arrangement of the storage tanks 2 is not limited to the illustrated example. For example, the storage tank 1 of the present invention can be configured by arranging the storage tank 2 at each vertex position of a triangle or a polygon of pentagon or more. Further, even when a plurality of storage tanks 2 are arranged in a line, the boundary heat medium pipes 10R are provided in a row along the boundary line R of the storage tanks 2 to simultaneously control the frozen ground F on both sides. By doing, it is also possible to set it as the value storage facility 1 of this invention which suppresses the maintenance management cost of the frozen ground F.

  Moreover, the amount of BOG generation | occurrence | production is produced by storing the low temperature liquefied gas LG, using the storage tank 2 which has the diameter reduced diameter guide shaft part 2b like the example of illustration, and maintaining a liquid level in the guide hole part 2b. However, it is difficult to completely suppress the generation of BOG, and during the storage of the liquefied gas LG for a long period of time, BOG is gradually generated and accumulated in the main body portion 2 and the guide shaft portion 2b. sell. In the illustrated example, the internal pressure of the storage tank 2 is detected by a pressure gauge 7a of the BOG line 6, and the opening degree of the pressure control valve 8 is adjusted by a control signal of the pressure control device 7 according to the detection signal, thereby causing the BOG line 6 to The BOG accumulated in the guide shaft portion 2b is appropriately discharged, and the storage tank 2 is maintained at an appropriate internal pressure (for example, a positive pressure of about 10 kPa). It is also possible to provide a BOG compressor 9 in the BOG line 6 as necessary, and convert the discharged BOG into a compressed liquid and return it to the storage tank 2. The liquefied gas LG in the storage tank 2 can be discharged through the discharge line 5 and the vaporizer 5a by the pump P at the bottom of the main body 2 as necessary.

  FIG. 3 shows another embodiment of the underground freezing control type storage facility of the present invention including the heat medium circulating device 15 and the heat medium switching means 19 for switching the heating heat medium T and the cooling heat medium T ′. As described with reference to FIGS. 1 and 2, in the storage facility 1 of the present invention, the annular heat medium pipe 10U and the boundary heat outer pipe 10R provided in a row along the periphery and boundary of the storage tank 2 are respectively provided. Although the thickness of the frozen ground F can be economically controlled by circulating the heating medium T from the heating medium circulating device 15, each heating medium tube can be obtained by circulating the cooling heating medium T ′ from the circulating device 15. 10U and 10R can be used for purposes other than controlling the thickness of the frozen ground F. The circulation device 15 in the illustrated example is connected to a heat source 18 and a cold source 17 via a heating medium switching means 19 such as a switching valve, and the switching means 19 causes a heating heat medium T and a cooling heat medium T ′ to be connected. Can be switched and supplied to the heat medium pipes 10U and 10R.

  3 (A) to 3 (C), an annular heat medium pipe 10U and a boundary heat outer pipe 10R are drilled prior to excavation of the storage tank 2 in the storage facility 1 of the present invention (FIG. 3 (A)). The frozen ground region F is formed by circulating the cooling heat medium T ′ through each of the heat medium pipes 10U and 10R (FIG. 5B), and each frozen storage region F is vertically excavated to construct each storage tank 2. (Example (C)). That is, for example, in FIG. 2A, the heat medium pipe 10U along the outer annular line U and the heat outer pipe 10R along the boundary line R are perforated prior to the construction of the storage tank 2, and each heat is supplied from the circulation device 15. The cooling medium T ′ is introduced into the medium pipes 10U and 10R, and the ground is solidified and stabilized by forming the frozen ground region F inside the outer annular line U. The ground is perpendicular to the frozen ground region F from the surface E. The storage tank 2 is constructed by a freezing method in which the guide shaft portion 2b having a diameter W3 is first excavated downward to a predetermined depth D, further expanded to the diameter W2 and the main body portion 2a is excavated vertically downward. However, the freezing method is not essential for the present invention, and the storage tank 2 and the heating medium pipes 10U and 10R can be constructed by directly excavating a stable hard ground or the like as it is.

  After constructing a plurality of storage tanks 2 in FIG. 3 (C), the low-temperature liquefied gas LG is received after laying the receiving line 4, the dispensing line 5, the BOG line 6 and the like. The formed frozen ground region F is also effective for cool-down that reduces the amount of BOG generated when receiving the low-temperature liquefied gas LG. That is, as in the case of FIG. 3B, the cooling medium T ′ is circulated through the heating medium pipes 10U and 10R before the cold and liquefied gas LG is received after the storage tank 2 is completed. Is frozen to form a frozen ground region F for cool-down. In addition, when a cryogenic liquefied gas LG (for example, LNG at −162 ° C.) is directly put into the room temperature storage tank 2, the thermal environment changes drastically, and a large thermal stress is generated until the whole reaches a stable state. Since there is a possibility of occurrence in various places of the structure, the precooling around the storage tank 2 by circulating the cooling medium T ′ to the heating medium pipes 10U, 10R has the effect of alleviating this dramatic change in temperature environment. Can also be expected. After the cold / hot liquefied gas LG is received in each storage tank 2, the switching means 19 of the circulation device 15 is switched to circulate the heating medium T in the heating medium tubes 10U, 10R, referring to FIG. 1 and FIG. As described above, the cold / hot liquefied gas LG is stored for a long period of time while controlling the thickness of the frozen ground F around each storage tank 2.

DESCRIPTION OF SYMBOLS 1 ... Underground storage facility 2 ... Storage tank 2a ... Main part 2b (of storage tank) Leading part 4 (of storage tank) 4 Reception line 5 ... Discharge line 5a ... Vaporizer 6 ... BOG line 7 ... Pressure control apparatus 7a DESCRIPTION OF SYMBOLS ... Pressure gauge 8 ... Pressure control valve 9 ... BOG compressor 10U ... Annular heat medium pipe 10R ... Boundary heat medium pipe 10N ... Inner heat medium pipe 15 ... Circulation device 16 ... Circulation control means 17 ... Cooling heat source 18 ... Heat source 19 ... Switching means 20 ... underground storage tank 21 ... underground connecting wall 22 ... bottom wall 23 ... side wall 24 ... roof 25 ... notch 26 ... membrane 27 ... side heater 28 ... bottom heater D ... depth of top end of main body of storage tank E ... Ground surface F ... Frozen ground G ... Mutual gap (gap) between heat transfer tubes
L: Depth (length in the vertical direction) LG ... Low temperature liquefied gas N ... Inner zone P ... Pump Q ... Excavation point of storage tank R ... Boundary line S ... Distance between storage tank and heat transfer pipe T ... Heat transfer medium (heat) )
T '... heat medium (cold heat) U ... annular line W2 ... diameter of main part of storage tank W3 ... diameter of main shaft part of storage tank

Claims (7)

Cold and liquefied liquefied gas storage tanks constructed by vertically excavating a plurality of points separated from each other on the ground surface, heat transfer pipes vertically drilled at a plurality of positions along an annular line surrounding the points, and the adjacent points A heat medium pipe vertically drilled at a plurality of positions along a boundary line between the heat medium pipes, and a heat medium circulation device that circulates the heat medium in each heat medium pipe. Low temperature liquefied gas underground freezing controlled storage facility with controlled freezing. 2. The storage facility according to claim 1, wherein the heat medium circulation device includes a control means for independently controlling circulation of the heat medium with respect to each heat medium pipe. 3. The storage facility according to claim 1 or 2, wherein the plurality of points are polygonal apex positions on the ground surface. The storage facility according to claim 3, wherein inner heat medium pipes are vertically drilled at a plurality of positions along a peripheral edge of the inner area surrounded by the plurality of points, from the heat medium circulation device to each inner heat medium pipe. An underground freezing controlled storage method for low-temperature liquefied gas that prevents freezing of the inner zone by circulating a heat medium. The storage facility according to any one of claims 1 to 4, wherein the heating medium circulating device includes heating medium switching means for switching between a heating heating medium and a cooling heating medium, and before receiving the cold and liquefied liquefied gas in each of the storage tanks. A cooling heat medium is circulated in each heat medium pipe to freeze around the storage tank, and after receiving, a heating heat medium is circulated in each heat medium pipe to control freezing around the storage tank. Underground freezing controlled storage facility. In the storage facility according to any one of claims 1 to 5, a freezing region formed by piercing each heat medium pipe in advance of each storage tank and circulating a heat medium for cooling through each heat medium pipe. A cryogenic liquefied gas underground freezing controlled storage facility constructed by digging vertically and building each storage tank. 7. A storage facility according to claim 1, wherein a main body portion having a predetermined diameter extending vertically downward from a predetermined depth underground and a top end of the main body portion are connected to the ground surface with a reduced diameter in each storage tank. An underground freezing controlled storage facility for low-temperature liquefied gas that is stored in the storage tank while receiving a low-temperature liquefied gas that is larger than the volume of the main body and keeping the liquid level in the guide pit.

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