JP2014015227A - Tank for storing low-temperature liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tank for storing a low-temperature liquid which can surely eliminate outside tensile bending moment and tensile stress occurring in an underside end of a dike, and reduce an amount of a longitudinal PC steel material and a reinforcing steel (steel material amount).SOLUTION: In a concrete tank body part 10 composed of a bottom plate 2 and a dike 3, a plurality of longitudinal PC steel materials 11 for introducing pre-stress in a vertical direction of the tank body part 10 and a plurality of lateral PC steel materials 7 for introducing the pre-stress in a peripheral direction of the tank body part 10 are buried. In the longitudinal PC steel material 11, a PC steel rod provided with a fixing part is used in an upper end 11b side and in an under end 11a side, and the longitudinal PC steel materials 11 are compactly arranged in an under end 3a side of the tank body part 10 and are arranged with an interval in the peripheral direction of the tank body part 10. Furthermore, the longitudinal PC steel materials 11 adjacent to each other in the peripheral direction are arranged so that positions of both upper ends 11b shift vertically from each other and positions of both under ends 11a shift vertically from each other.

Description

  The present invention relates to a cryogenic liquid storage tank used for storing a cryogenic liquid such as liquefied natural gas.

  Conventionally, as shown in FIG. 5, a tank for storing a low temperature liquid 1 such as liquefied natural gas (LNG) or liquefied petroleum gas (LPG) (low temperature liquid storage tank A) includes a bottom plate 2 and a bottom plate 2. A cylindrical breakwater 3 that is erected by connecting the lower end 3 a to the bottom, and a metal storage tank (inner tank) 4 that is disposed inside the bottom plate 2 and the breakwater 3. There is something configured. Further, this type of cryogenic liquid storage tank A is generally provided with a flat plate-like or dome-like roof 5 at the top, and a cold insulating material 6 is provided between the storage tank 4 and the bottom plate 2, the liquid barrier 3 and the roof 5. Provided and constructed (see, for example, Patent Document 1 and Patent Document 2).

  The breakwater 3 is used to localize (prevent) the diffusion of the low temperature liquid 1 in the unlikely event that the low temperature liquid 1 leaks from the storage tank 4, and its lower end 3 a is rigidly connected to the bottom plate 2. Is provided. Furthermore, the breakwater 3 is constructed of reinforced concrete and is constructed by introducing prestress by the transverse PC steel material 7 arranged in the circumferential direction (lateral direction). The prestress by the transverse PC steel material 7 causes cracking. Generation | occurrence | production is prevented and the low temperature liquid 1 can be reliably hold | maintained at the time of a liquid leak.

  Further, the pre-stress acting in the circumferential direction on the liquid breakwater 3 generates an external tensile bending moment on the lower end 3 a side, and consequently, a tensile stress on the outer peripheral surface 3 b side on the lower end 3 a side of the liquid breakwater 3. Further, the bottom plate 2 is heated by a heater (the heater 8 embedded in the bottom plate 2) so that the ground G under the bottom plate 2 is not frozen. Under the influence of outside temperature, the summer expands and the winter contracts. When contracted due to such seasonal fluctuations, an external tensile bending moment is generated on the lower end portion 3a side of the breakwater 3 and a tensile stress is generated on the outer peripheral surface 3b side on the lower end portion 3a side.

  For this reason, as shown in FIGS. 5 and 6, the breakwater 3 has an intermediate portion with a thickness on the lower end 3a side for the purpose of counteracting the external tensile bending moment and tensile stress generated mainly by the above factors. , Larger than the general portion on the upper end 3c side, and the amount of bar arrangement on the lower end 3a side portion is increased. 9 is embedded and prestress is introduced in the vertical direction. At this time, the breakwater 3 is on the outer peripheral surface 3b side radially outside the longitudinal PC steel 9 so as to surround the plurality of longitudinal PC steels 9 arranged at predetermined intervals in the circumferential direction. The horizontal PC steel material 7 is disposed on the side.

Japanese Patent No. 3839448 JP 2005-350092 A

  Here, it is desirable that the vertical PC steel material 9 is disposed in a proper amount in a proper position so that the external tensile bending moment and tensile stress generated on the lower end 3a side of the breakwater 3 can be canceled. Actually, as in the conventional case, the vertical tendon 9 is used to dispose prestress in a wide range from the lower end 3a to the upper end 3c of the breakwater 3. The conventional breakwater 3 is constructed by arranging a large number of reinforcing bars in the lower end portion 3a side portion in order to resist the external tensile bending moment and tensile stress generated on the lower end portion 3a side. ing. For this reason, in the conventional low-temperature liquid storage tank A (breakwater 3), it has been strongly desired to reduce the amount of steel as much as possible and to reduce the cost.

  In view of the above circumstances, the present invention can reduce the amount of vertical PC steel and reinforcing bars (the amount of steel material) while reliably canceling the external tensile bending moment and tensile stress generated on the lower end side of the breakwater. It is an object of the present invention to provide a cryogenic liquid storage tank that makes it possible.

  In order to achieve the above object, the present invention provides the following means.

  The cryogenic liquid storage tank according to the present invention is disposed in a bottom plate, a cylindrical liquid breakwater standing upright with a bottom end rigidly connected to the bottom plate, and an interior surrounded by the bottom plate and the liquid breakwater. A cryogenic liquid storage tank comprising a storage tank for storing a cryogenic liquid, wherein the concrete tank main body portion including the bottom plate and the liquid barrier is prestressed in the vertical direction of the tank main body portion. A plurality of vertical PC steel materials to be introduced and a plurality of horizontal PC steel materials to introduce prestress in the circumferential direction of the tank main body are embedded, and the vertical PC steel materials have fixing portions on the upper end side and the lower end side. PC steel rods are used, and the vertical PC steel material is intensively arranged on the lower end side of the tank main body part, and is arranged at intervals in the circumferential direction of the tank main body part, and The vertical PC steel materials adjacent to each other in the circumferential direction Characterized in that it is arranged by shifting the location vertically.

  Moreover, in the cryogenic liquid storage tank of the present invention, it is desirable that the vertical PC steel material is disposed closer to the outer peripheral surface of the tank body than the horizontal PC steel material.

  In the low-temperature liquid storage tank of the present invention, the vertical PC steel material of the PC steel rod is arranged on the lower end side of the breakwater where an external tensile bending moment and tensile stress are generated, so that it is reliably and effectively performed. It is possible to cancel the external tensile bending moment and tensile stress.

  Moreover, at this time, the vertical PC steel materials adjacent to each other in the circumferential direction are arranged by shifting the positions of the upper ends and the lower ends of each other up and down, so that the vertical PC steel materials are densely arranged in the circumferential direction. It becomes possible to counteract the external tensile bending moment and tensile stress by the longitudinal PC steel material more reliably and effectively. It is possible to reduce the amount of reinforcing bars.

  Thereby, in the cryogenic liquid storage tank of the present invention, by introducing the prestress by the vertical PC steel material, it is possible to surely cancel out the external tensile bending moment and tensile stress generated on the lower end side of the breakwater. In addition, it becomes possible to reduce the amount of vertical PC steel and reinforcing bars (the amount of steel), and it is possible to construct a low-temperature liquid storage tank at a lower cost than in the past.

  Further, in the low-temperature liquid storage tank of the present invention, the vertical PC steel is disposed on the outer peripheral surface side of the tank main body portion rather than the horizontal PC steel, so that the vertical PC steel is changed from the horizontal PC steel as in the prior art. Compared with the case where it is arranged on the inner surface side of the tank main body, it is possible to effectively cancel the external tensile bending moment and the tensile stress by the prestress by the vertical PC steel material. Thereby, it is possible to reduce the amount of vertical PC steel for canceling the external tensile bending moment and tensile stress, and to further reduce the amount of steel and to reduce the cost of the cryogenic liquid storage tank.

It is sectional drawing which shows the cryogenic liquid storage tank which concerns on one Embodiment of this invention. It is a figure which shows an example of the arrangement | positioning state of the reinforcing bar and PC steel material of the lower end part side of the breakwater (tank main-body part) of the cryogenic liquid storage tank which concerns on one Embodiment of this invention. It is a figure which shows the arrangement | positioning state of the vertical PC steel material of the lower end part side of the breakwater (tank main-body part) of the cryogenic liquid storage tank which concerns on one Embodiment of this invention. It is a figure which shows an example of the arrangement | positioning state of the reinforcing bar and PC steel material of the upper end part side of the breakwater (tank main-body part) of the cryogenic liquid storage tank which concerns on one Embodiment of this invention. It is sectional drawing which shows the conventional tank for low-temperature liquid storage. It is a figure which shows an example of the arrangement | positioning state of the reinforcing bar and PC steel material of the lower end part side of the breakwater (tank main-body part) of the conventional cryogenic liquid storage tank.

  Hereinafter, a cryogenic liquid storage tank according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. The present embodiment relates to a tank used for storing a low-temperature liquid such as liquefied natural gas.

  As shown in FIG. 1, the low-temperature liquid storage tank B of the present embodiment is a flat plate-shaped bottom plate 2, a cylindrical breakwater 3, and a low-temperature liquid 1, as in the conventional low-temperature liquid storage tank A. It is constructed with a metal storage tank 4, a roof 5, and a cold insulation material 6. In the present embodiment, the tank body 10 is constituted by the liquid barrier 3 and the bottom plate 2.

  Further, the liquid breakwater 3 is made of reinforced concrete, prevents the occurrence of cracks, and the horizontal PC steel material 7 arranged in the circumferential direction for the purpose of securely holding the low temperature liquid 1 at the time of leakage, and the liquid breakwater 3 Is formed by embedding in concrete a vertical PC steel material 11 arranged in the vertical direction for the purpose of canceling the external tensile bending moment and tensile stress generated on the lower end 3a side. In other words, the breakwater 3 is constructed as a prestressed concrete structure in which prestress is introduced in each of the circumferential direction and the vertical direction.

  Further, the liquid breakwater 3 is formed such that the lower end 3a side rigidly connected to the bottom plate 2 gradually increases in thickness as it goes from the upper end 3c side to the lower end 3a. Then, the outer peripheral surface 3b of this thickened portion is formed as a tapered surface that is gradually inclined outward in the radial direction toward the lower end portion 3a. Further, the breakwater 3 is thickened by providing a step on the upper end 3c side, and a portion having a certain thickness in the middle in the vertical direction is a general portion. The lower end 3a side of the breakwater 3 may be formed with a large thickness by providing a step, similarly to the upper end 3c side.

  Further, in the breakwater 3 of the present embodiment, as shown in FIGS. 1 to 3, PC steel as a vertical PC steel material is formed along the tapered surface (or along the vertical direction) on the lower end 3 a side. A plurality of bars 11 are arranged. Further, at this time, the plurality of PC steel bars 11 are provided with the lower end 11a fixed to the bottom plate 2 and the upper end 11b fixed to a general part located slightly above the tapered surface. Further, as shown in FIG. 3, the plurality of PC steel bars 11 are arranged at predetermined intervals in the circumferential direction, and the PC steel bars 11 adjacent to each other in the circumferential direction are connected to each other between the upper ends 11 b and the lower ends. 11a is shifted up and down. That is, the other PC steel bar 11 is shifted up and down with respect to one PC steel bar 11 adjacent in the circumferential direction, and a plurality of PC steel bars 11 are alternately shifted up and down.

  Further, in the present embodiment, as shown in FIGS. 1 to 3, the plurality of PC steel bars 11 are disposed on the radially outer side of the breakwater 3 relative to the horizontal PC steel material 7, that is, on the outer peripheral surface 3 b side. Yes.

  Furthermore, in the breakwater 3 of this embodiment, as shown in FIG.1 and FIG.4, multiple PC steel rods 12 as vertical PC steel material are arrange | positioned along the vertical direction also at the upper end part 3c. Yes.

  In the low-temperature liquid storage tank B of the present embodiment having the above-described configuration, first, the PC steel rod 11 (12) is used as the vertical PC steel material, and the breakwater 3 in which the external tensile bending moment and tensile stress are generated. By being arranged intensively on the lower end 3a side and introducing pre-stress, that is, by placing the PC steel material 11 at the right place and introducing pre-stress, it is reliable and effective. Thus, the external tensile bending moment and tensile stress are canceled out.

  Further, the PC steel bars 11 adjacent to each other in the circumferential direction are arranged by shifting the positions of the upper ends 11b and the lower ends 11a, which are fixing portions of the PC steel bars 11, up and down, thereby providing a plurality of PC steel bars. 11 can be densely arranged in the circumferential direction. For this reason, pre-stress can be introduced more effectively by each PC steel rod 11, and the outer tensile bending moment and tensile stress are canceled out surely and effectively, and accordingly, on the lower end 3a side of the breakwater 3 The amount of reinforcing bars can be reduced.

  Furthermore, by arranging the plurality of PC steel bars 11 on the outer side in the radial direction of the breakwater 3 than the horizontal PC steel material 7, that is, on the outer peripheral surface 3b side where a larger tensile stress is generated, the PC steel bars The prestress by 11 will cancel the tensile stress more effectively.

  Therefore, in the cryogenic liquid storage tank B of the present embodiment, the vertical PC steel material 11 of the PC steel bar is arranged on the lower end 3a side of the breakwater 3 where the external tensile bending moment and tensile stress are generated. Thus, the external tensile bending moment and tensile stress can be canceled out reliably and effectively.

  At this time, the vertical PC steel materials 11 adjacent to each other in the circumferential direction are arranged by shifting the positions of the upper ends 11b and the lower ends 11a from each other up and down. It is possible to dispose the outer tensile bending moment and tensile stress by the longitudinal PC steel material 11 more reliably and effectively.

  Thereby, in the low-temperature liquid storage tank B of the present invention, the introduction of prestress by the vertical PC steel material 11 surely cancels the external tensile bending moment and tensile stress generated on the lower end portion 3a side of the liquid-proof bank 3. It is possible to reduce the amount of the vertical PC steel material 11 and the reinforcing bars (the amount of steel material) while enabling the low-temperature liquid storage tank B to be constructed at a lower cost than in the past.

  Further, in the cryogenic liquid storage tank B of the present embodiment, the vertical PC steel material 11 is disposed closer to the outer peripheral surface 3b side of the tank body 10 than the horizontal PC steel material 7, so that the conventional vertical PC steel material is used. Compared with the case where 9 is disposed closer to the inner surface side of the tank body 10 than the horizontal PC steel material 7, the external tensile bending moment and the tensile stress can be effectively canceled by the prestress by the vertical PC steel material 11. Thereby, it is possible to reduce the amount of the vertical PC steel material 11 for canceling the external tensile bending moment and the tensile stress, and to further reduce the amount of the steel material and to reduce the cost of the low-temperature liquid storage tank B. .

  As mentioned above, although one embodiment of the cryogenic liquid storage tank according to the present invention has been described, the present invention is not limited to the above embodiment, and can be appropriately changed without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Low temperature liquid 2 Bottom plate 3 Liquid breakwater 3a Lower end part 3b Outer peripheral surface 3c Upper end part 4 Storage tank 5 Roof 6 Cold insulation material 7 Horizontal PC steel material 8 Heater 9 Vertical PC steel material (vertical tendon)
10 Tank body 11 Vertical PC steel (PC steel bar)
11a Lower end 11b Upper end 12 Vertical PC steel (PC steel bar)
A A conventional cryogenic liquid storage tank B A cryogenic liquid storage tank

Claims (2)

A bottom slab, a cylindrical liquid breakwater erected with a bottom end rigidly connected to the bottom slab, and a storage tank for storing a cryogenic liquid disposed inside the bottom slab and the liquid breakwater A cryogenic liquid storage tank provided,
A concrete tank body made of the bottom plate and the liquid barrier is introduced with a plurality of vertical PC steel materials for introducing prestress in the vertical direction of the tank body and prestress in the circumferential direction of the tank body. A plurality of horizontal PC steel materials are embedded,
For the vertical PC steel, a PC steel rod having fixing portions on the upper end side and the lower end side is used,
The vertical PC steel material is intensively arranged on the lower end side of the tank main body, and is arranged at intervals in the circumferential direction of the tank main body and adjacent to the circumferential PC. A cryogenic liquid storage tank, characterized in that the steel materials are arranged by shifting the positions of the upper and lower ends of each other up and down. The cryogenic liquid storage tank according to claim 1,
The cryogenic liquid storage tank, wherein the vertical PC steel is disposed closer to the outer peripheral surface of the tank body than the horizontal PC steel.

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