JP6310603B1 - Underground tank structure - Google Patents

Abstract

An underground tank structure capable of reducing a temperature load applied to a tank housing is provided. An underground tank structure 1 stores a low-temperature liquefied gas such as LNG, has a tank housing including a bottom plate 5 and a side wall 7, and has a freezing line b indicating a position at which the temperature becomes 0 ° C. as the tank is operated. The bottom plate 5 and the side wall 7 are located at substantially the same distance from the inner surface of the tank housing. The position of the freezing line b is managed by circulating a heat medium through the heater tubes 13 and 22 at the side and bottom of the tank housing, and the heater tubes 13 and 22 are arranged at substantially the same distance from the inner surface of the tank housing. Is done. [Selection] Figure 1

Description

  The present invention relates to an underground tank structure provided with a heater facility.

  There is an underground tank as a facility for storing low-temperature liquefied gas such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas). In recent underground tanks, after excavating the inside of the underground continuous wall, which is a mountain retaining, a tank frame comprising a bottom slab 5 made of reinforced concrete and a side wall 7 is constructed inside the underground continuous wall 9 as shown in FIG. In general, a steel roof 8 is provided thereon. Although illustration is omitted, a membrane is provided on the inner surface of the tank housing via a heat insulating material. A water collecting layer 4 made of crushed stone or the like is provided below the bottom plate 5.

  The bottom plate 5 and the side wall 7 may be pin-coupled or slide-coupled, but recently, the bottom plate 5 and the side wall 7 are often connected and integrated to form a rigid connection. This is due to the advantage of the water stop surface and the need for a support structure between the bottom plate 5 and the side wall 7. In the case of such a structure type, it is common to provide a haunch 6 at the corners of the bottom plate 5 and the side wall 7 to smooth the flow of stress.

  Because underground tanks store liquefied gas such as LNG at low temperatures, heaters are installed on the side and bottom to prevent freezing of the surrounding ground when the tank is operating, and temperature stability is achieved. The position of the line indicating the position is maintained and managed (for example, Patent Documents 1-5). Some heater equipment uses a planar heating element, but many of them control the position of the freezing line by circulating a heat medium through the heater tube and exchanging the heat.

  In the example of FIG. 14, a heater tube 103 is embedded in the surrounding ground 3 as a side heater facility. The heater pipe 103 is, for example, a double pipe type in which an inner pipe is inserted into an outer pipe, and the upper end of the inner pipe and the outer pipe is connected to the header pipe 101 on the heat medium supply side via the branch pipe, and the header pipe on the recovery side. 105, respectively. In the side heater facility, the freezing line is managed at a position about 1 m outside the underground continuous wall 9 by exchanging heat between the heat medium in the heater tube 103 and the surrounding ground 3.

  On the other hand, as the bottom heater equipment, a brine heater for circulating a heat medium is installed in a heater tube 201 embedded in the vicinity of the lower surface of the bottom slab 5, and the freezing line is managed at the bottom of the bottom slab 5 so that the ground below the bottom slab 5 Prevents freezing.

Japanese Patent Laid-Open No. 11-182797 Japanese Patent Publication No.61-31360 Japanese Unexamined Patent Publication No. 8-145297 Patent No. 2789299 Japanese Patent Publication No.58-6118

  A load caused by a temperature drop of the tank housing and a load caused by a temperature difference between the tank housings are applied to the tank housing of the underground tank. The former is a load generated when the temperature of the tank housing constructed at normal temperature is lowered by the low-temperature liquefied gas when the tank is operating, and the latter is a load generated by a temperature difference between the inner and outer surfaces of the tank housing.

  In the former case, the contraction of the bottom plate and the side wall accompanying the temperature drop is constrained by the frictional force with the surrounding ground, so that an axial force (temperature load) is generated in the cross section of the bottom plate and the side wall.

  In the latter case, the temperature of the inner surface of the tank housing is lowered by the low-temperature liquefied gas such as LNG when the tank is in operation, but the temperature of the outer surface of the side wall is not lowered because it is heated by the side heater equipment. A temperature difference occurs between the inner surface of the side wall (the inner surface of the tank housing). Similarly, a temperature difference also occurs between the lower surface of the bottom plate in which the heater pipe is embedded and the upper surface of the bottom plate (the inner surface of the tank housing). In this case, the inner surface of the side wall and the upper surface of the bottom plate, where the temperature decreases, tend to shrink, but a bending moment (temperature load) is generated by restraining the shrinkage by the side wall and the bottom plate.

  As a result of such a temperature load, the underground tank needs to be reinforced by increasing the amount of reinforcing bars on the bottom plate and the side wall, which causes an increase in the cost of the underground tank.

  This invention is made | formed in view of said problem, and it aims at providing the underground tank structure which can reduce the temperature load added to a tank housing.

The present invention for solving the above-mentioned problem is an underground tank structure provided on the ground, and has a tank casing including a bottom plate and a side wall, and a freezing line indicating a position at which the tank becomes 0 ° C. as the tank is operated, position near made in the bottom plate and the side wall from the inner surface of the tank skeleton substantially the same separation distance is, the position of the frost line is, the heater tube side of said tank skeleton, the heater tube the bottom of the tank skeleton The heater tube at the side of the tank housing and the heater tube at the bottom of the tank housing are arranged at substantially the same distance from the inner surface of the tank housing, and are managed by circulating a heat medium. A side heater pipe is embedded in the side wall of the tank casing, and the freezing line is formed inside the heater pipe on the side of the tank casing .

  In the present invention, in the tank housing including the bottom plate and the side wall, the position of the freezing line is set in the side wall so as to be close to the inner surface of the tank housing. It is set so as to be substantially the same as the freezing line in the side wall. As a result, the distance between the inner surface of the tank housing and the freezing line is the same on the bottom plate and the side wall, and the position of the freezing line is close to the inner surface of the tank housing. However, it is preferable. That is, the amount of temperature drop from the time of construction of the tank housing can be made as small as possible, the temperature difference between the inner and outer surfaces of the tank housing can be reduced, and the amount of rebar can be reduced by extremely reducing the temperature load. It is. In addition, since the frozen concrete having substantially the same thickness can be formed on the tank housing, a reliable and reliable water stop can be achieved.

Position of the frozen connections can be managed by circulating heat medium to the heater tube side and the bottom of the tank skeleton. By making these heater tubes the same distance from the inner surface of the tank housing, the distance from the inner surface of the tank housing to the freezing line can be easily aligned between the bottom plate and the side wall.

It is often provided a heater tube surrounding ground in traditional second heater equipment, close to the inner surface of the tank precursor by the heater tube in the present invention is embedded in the side walls, located close to the inner surface of the tank precursor freezing line Can be managed with. In addition, drilling work when installing a heater pipe on the surrounding ground is unnecessary, and construction is facilitated.

It is desirable that the heater tube at the side of the tank housing and the heater tube at the bottom of the tank housing are continuous.
By making the side and bottom heater pipes of the tank housing continuous, it is easier to align the distance from the inner surface of the tank housing to the freezing line between the bottom plate and the side wall.

For example, the heater pipe at the bottom of the tank housing is arranged in a substantially horizontal direction, both ends are connected to the heater pipe on the side of the tank housing, and the heater pipe on the side of the tank housing is arranged in a substantially vertical direction. The heater tube at the bottom of the tank housing is arranged in a substantially V-shaped or L- shaped shape on a plane.
In addition, a plurality of heater tubes may be provided at the bottom of the tank housing, and the plurality of heater tubes at the bottom of the tank housing may be arranged such that the position of the bent tip is at a different distance from the plane center of the bottom plate. .
In this case, the side and bottom heater tubes are made continuous so that it is easy to make the separation distance uniform as described above. Cost.

The heater pipe at the side of the tank casing and the heater pipe at the bottom of the tank casing preferably have pipes arranged along the circumferential direction of the tank casing.
In addition, hunches are provided at the corners of the bottom plate and the side wall, the pipes of the heater pipes at the bottom of the tank housing are arranged in a substantially spiral shape, and the pipes at the outer peripheral part are located higher on the outer side. It may be arranged along the inclination of the haunch.
Thus, by making the heater tube of the side part and the bottom part of the tank housing have a similar annular structure, it is possible to easily prevent the freezing line from coming out at the corner part of the bottom plate and the side wall.

The bottom plate and the side wall are preferably rigidly connected.
Since the temperature load often increases when the bottom plate and the side wall are rigidly connected, the present invention can be particularly suitably applied in such a case.
The heater pipe at the bottom of the tank housing is preferably embedded between the outer periphery of the bottom plate and the plane center of the bottom plate, and has a substantially the same pipe diameter from the outer periphery to the plane center.

  The present invention can provide an underground tank structure capable of reducing the temperature load applied to the tank housing.

The figure which shows the underground tank structure 1. FIG. The figure which shows arrangement | positioning of the heater pipe | tube 13. FIG. The figure which looked at the plane of heater pipe 22. FIG. The example of the temperature distribution of the side wall 7 and the bottom plate 5 is shown. The figure which shows heater pipe | tube 13 '. The figure which shows the underground tank structure 1a. The figure which shows the heater pipe | tube 13a. The figure which shows the example which makes the heater pipes 13a and 22 continue. The figure which shows heater pipe | tube 13a '. The figure which shows the underground tank structure 1b. The figure which shows the plane of the heater pipe | tube 32. FIG. The figure which shows the plane of the heater pipe | tube 32a. The figure which shows the plane of the heater pipe | tube 32b. An example of a conventional underground tank.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(1. Underground tank structure 1)
FIG. 1 is a diagram showing an underground tank structure 1 according to a first embodiment of the present invention. The underground tank structure 1 is provided on the ground, and stores (extremely) low-temperature liquefied gas (low-temperature liquid) such as LNG or LPG in the tank.

  As in the example of FIG. 14, the underground tank structure 1 excavates the inside of the underground continuous wall 9, which is a mountain retaining, and then constructs the tank frame with the bottom slab 5 and the side wall 7 made of reinforced concrete inside the underground continuous wall 9. The steel roof 8 is provided thereon. Although not particularly illustrated, a heat insulating material is provided on the inner surface of the tank housing, and a membrane and the like are further provided on the inner side. “Inside” means the one closer to the center of the tank housing, and “outside” means the opposite side.

  The side wall 7 is formed in a cylindrical shape on the bottom plate 5 and is thinner than the bottom plate 5. The bottom plate 5 and the side wall 7 are connected and integrated (rigidly connected), and a haunch 6 is provided at a corner portion thereof. The underground continuous wall 9 is provided in a cylindrical shape in the peripheral ground 3 outside the side wall 7. A water collection layer 4 made of crushed stone or the like is also provided below the bottom plate 5.

  Since underground tanks store low-temperature liquefied gases of less than 0 ° C, especially about -160 ° C, such as LNG, as in the example of Fig. 14, A partial heater facility and a bottom heater facility are provided.

  The side heater equipment is a circulation type heater equipment that circulates a heat medium, and includes a heating equipment, a circulation pump (not shown), header pipes 11 and 15, a heater pipe 13 and the like. The heater tube 13 is a heater tube on the side of the tank housing and is provided in the side wall 7. The header pipes 11 and 15 are provided in an annular shape along the circumferential direction of the tank housing at the top of the side wall 7.

  In the side heater equipment, the heating medium is circulated in the order of the heating equipment and the circulation pump, the header pipe 11, the heater pipe 13, the header pipe 15, and the heating equipment, and the concrete of the side wall 7 and the heat medium in the heater pipe 13 are circulated. Heat exchange between them.

  The bottom heater equipment is also a circulation type heater equipment that circulates the heat medium. The heat medium is supplied to the heater pipe 22 (the heater pipe at the bottom of the tank housing) in the bottom plate 5 using a heating equipment or a circulation pump (not shown). The heat is exchanged between the concrete of the bottom plate 5 and the heat medium in the heater tube 22 by circulation.

  In this embodiment, the heater pipe 13 of the side heater equipment and the heater pipe 22 of the bottom heater equipment are arranged along a line segment a similar to the inner surface shape of the tank housing as a whole, and the inner surface of the side wall 7 (the tank housing) The separation distance from the inner surface) to the heater tube 13 and the separation distance from the upper surface of the bottom plate 5 (the inner surface of the tank housing) to the heater tube 22 are substantially the same. This separation distance is about 2.5 m, for example.

  Each heater facility circulates a heat medium through the heater pipes 13 and 22, and performs heat exchange between the heat medium and the concrete of the side wall 7 and the bottom plate 5, so that the freezing line b enters the bottom plate 5 and the side wall 7. Maintain.

  In the present embodiment, by adjusting the pipe diameters of the heater pipes 13 and 22, the pipe interval, the temperature of the heat medium, etc., the freezing line b as a whole becomes a line segment similar to the inner surface shape of the tank housing, and the bottom plate 5 and the side wall 7, the separation distance from the inner surface of the tank housing to the freezing line b is made substantially the same. For example, the pipe diameters of the heater tubes 13 and 22, the interval between the pipes, and the temperature of the heat medium are the same, and the temperature of the heat medium is, for example, the surface average temperature of the heater pipes 13 and 22 (heater pipe line (the pipes of the heater pipes 13 and 22 The average temperature) of the side surfaces) should be about 3 ℃.

  The above separation distance is, for example, about 2.5 m from the inner surface of the tank housing, and frozen concrete having substantially the same thickness (about 1.5 m) is formed on the tank housing to realize efficient and reliable water stoppage. As the heat medium, an antifreeze such as Nybrine (registered trademark) is used to prevent the heat medium from freezing.

(2. Heater pipe 13 of side heater equipment)
FIG. 2 is a diagram showing the arrangement of the heater tubes 13 of the side heater equipment, and is a diagram showing a circumferential section of the side wall 7.

  As shown in FIG. 2, the heater pipe 13 is a plurality of pipes arranged at substantially equal intervals along the circumferential direction of the side wall 7 in the vicinity of the outer boundary portion of the side wall 7. The heater tube 13 is embedded and integrated in the concrete of the side wall 7 so as to follow the displacement of the side wall 7.

  The heater tube 13 is of the double tube type as described above, and is configured by inserting the inner tube 131 into the outer tube 132. For the outer tube 132, for example, an STPG tube (carbon steel tube for pressure piping) can be used.

  The upper end of the heater tube 13 protrudes from the top of the side wall 7, and the upper end of the inner tube 131 is connected to the header tube 11 on the heat medium supply side via a branch tube. The upper end of the outer pipe 132 is connected to the header pipe 15 on the heat medium recovery side via a branch pipe. The lower end of the heater tube 13 is below the upper end of the haunch 6. In the heater pipe 13, the heat medium supplied from the header pipe 11 passes through the inner pipe 131, passes between the inner pipe 131 and the outer pipe 132, and is collected in the header pipe 15.

  When the side wall 7 is constructed, a receiving jig (not shown) is installed on the inner surface of the underground continuous wall 9, and the outer tube 132 is temporarily received by the receiving jig and arranged. Thereafter, the reinforcing bars of the side walls 7 are installed, the outer pipes 132 are attached to the outer side of the outer reinforcing bars 41, the concrete of the side walls 7 is placed, the inner pipes 131 are inserted into the outer pipes 132, and the inner pipes 131 and the outer pipes are inserted. The upper end of 132 is connected to the header pipes 11 and 15 by branch pipes.

(3. Heater tube 22 of bottom heater equipment)
The heater tube 22 of the bottom heater facility is embedded in the concrete at the top of the bottom plate 5. The heater tube 22 is disposed at a higher position as compared with the case where the heater tube 22 is embedded in the lower surface of the bottom plate 5 as in the prior art.

  FIG. 3 is a plan view of the heater tube 22. In FIG. 3, the position of the bottom plate 5 and the side wall 7 disposed thereon and the position of the bottom plate 5 and the corner portion of the side wall 7 are indicated by broken lines.

  The heater tube 22 is arranged in a substantially spiral shape. More specifically, the heater pipe 22 has a plurality of circumferential pipes 222 arranged concentrically at substantially equal intervals. These circumferential pipes 222 are arranged along the circumferential direction of the tank housing, and the circumferential pipes 222 adjacent to each other inside and outside are connected by oblique pipes 223 inclined with respect to the circumferential pipe 222 in a plane, and are configured in a single stroke. Is done.

  The circumferential piping 222 is arranged on the upper portion of the bottom plate 5, but the circumferential piping 222 on the outer peripheral portion is arranged along the inclination of the haunch 6 so that the outer one is positioned on the upper side as shown in FIG. The outermost circumferential pipe 222 reaches the top of the haunch 6. Thereby, also in the corner part of the bottom plate 5 with the haunch 6 and the side wall 7, the separation distance from the inner surface of the tank housing to the freezing line b can be made uniform. The lower end of the heater pipe 13 on the side wall 7 is located below the outermost (uppermost) circumferential pipe 222 and prevents the freezing line b from coming out of the heater pipes 13 and 22 at the corner.

  The innermost circumferential pipe 222 and the outermost circumferential pipe 222 are respectively connected to substantially vertical vertical pipes 221 and 224 embedded in the side wall 7. These vertical pipes 221 and 224 protrude outward from the outer peripheral surface of the side wall 7 and form a closed flow path outside. Heating equipment and a circulation pump are arranged in this flow path.

(4. Temperature distribution in the side wall 7 and the bottom plate 5)
Figures 4 (a) and 4 (b) show the tank housing in an underground tank that stores LNG at -162 ° C. The tank housing has a side wall thickness of 2.35 m, a bottom plate thickness of 9.8 m, and an underground continuous wall thickness of 1.5 m. It is an example of the temperature distribution of the side wall 7 and the bottom slab 5 in the steady state when the tank is operating when the average temperature during construction is 16 ° C.

  4A and 4B, the distance A from the inner surface of the side wall 7 to the heater tube 13 is 2.35 m, and the distance from the upper surface of the bottom plate 5 to the heater tube 22 is 2.35 m. It is an example of the temperature distribution of the side wall 7 and the bottom plate 5 when the distance is substantially the same. The surface average temperature of the heater tubes 13 and 22 when the tank is operating (average temperature in the heater tube line) is 3 ° C.

  In this case, the freezing line b indicating the position at 0 ° C. is formed in the side wall 7 and the bottom plate 5, and the distance from the inner surface of the tank housing to the freezing line b is approximately the same as about 2.0 m on the side wall 7 and the bottom plate 5. The temperature difference between the inner surface and the outer surface of the side wall 7 is 19.6 ° C., and the temperature difference between the upper surface and the lower surface of the bottom plate 5 is 33.2 ° C. In addition, the temperature drop of the side wall 7 and the bottom slab 5 from the time of construction of the tank housing is 22.8 ° C. and 6.6 ° C. on average in the thickness direction.

  On the other hand, line B in FIGS. 4 (a) and 4 (b) indicates that the heater tube 103 of the side heater equipment is embedded in the peripheral ground 3 as shown in FIG. 14, and the distance from the inner surface of the side wall 7 is 5.85m. The heater tube 201 of the bottom heater equipment is embedded in the bottom surface of the bottom plate 5 so that the distance from the top surface of the bottom plate 5 is 9.8 m, and the surface average temperatures of the heater tubes 103 and 201 when the tank is operating are 8.0 ° C. and 10.0 ° C., respectively. This is an example.

  In this case, the temperature difference between the inner surface and the outer surface of the side wall 7 is 17.4 ° C., and the temperature difference between the upper surface and the lower surface of the bottom plate 5 is 63.3 ° C. In addition, the temperature drop of the side wall 7 and the bottom slab 5 from the time of construction of the tank housing is 40.7 ° C and 37.7 ° C on average in the thickness direction.

  As can be seen from the example of line A above, in this embodiment, the amount of temperature drop from the time of construction of the tank housing can be reduced as a whole, and the temperature difference between the inner surface and the outer surface of the tank housing is small (particularly in the bottom plate 5). Therefore, the temperature load is greatly reduced. As a result, the amount of reinforcing bars required for the bottom slab 5 and the side wall 7 is greatly reduced, and the construction cost of the underground tank can be reduced.

  As described above, in the present embodiment, in the tank housing including the bottom plate 5 and the side wall 7, the position of the freezing line b is set in the side wall 7 to approach the inner surface of the tank housing, and the freezing line b in the bottom plate 5. Is also set so that the distance from the inner surface of the tank housing is substantially the same as the freezing line b in the side wall 7. Accordingly, the bottom plate 5 and the side wall 7 have the same distance from the inner surface of the tank housing to the freezing line b, and the position of the freezing line b is close to the inner surface of the tank housing, thereby reducing the temperature load of the tank housing. It is advantageous from the viewpoint of the water stoppage.

  That is, as described above, the amount of temperature decrease from the time of construction of the tank housing can be made as small as possible, the temperature difference between the inner and outer surfaces of the tank housing can be reduced, the temperature load can be made extremely small, and the amount of rebar can be reduced. It is possible to reduce. In addition, since the frozen concrete having substantially the same thickness can be formed on the tank housing, a reliable and reliable water stop can be achieved.

  The position of the freezing line b can be managed by circulating a heat medium through the heater tubes 13 and 22 at the side and bottom of the tank housing. By making the distances of the heater tubes 13 and 22 from the inner surface of the tank housing the same, the distance from the inner surface of the tank housing to the freezing line b can be easily aligned between the bottom plate 5 and the side wall 7.

  Further, in the conventional side heater equipment, the heater pipe is often provided on the peripheral ground 3, but in this embodiment, the heater pipe 13 is embedded in the side wall 7 so as to be close to the inner surface of the tank casing, and the freezing line b is set in the tank. It can be managed at a position close to the inner surface of the housing. Also for the heater tube 22 of the bottom plate 5, the distance from the inner surface of the tank housing is the same as that of the heater tube 13 in the side wall 7, and is close to the inner surface of the tank housing.

  In addition, the heater tube 13 of the side heater facility can be constructed according to the above-described procedure, and the drilling operation when the heater tube is installed on the peripheral ground 3 is not necessary and the construction becomes easy. Since the heater pipe 13 is embedded in concrete, there is no need to use a PL pipe (polyethylene lining steel pipe) from the viewpoint of corrosion prevention as in the case where the heater pipe is embedded in the surrounding ground 3, and an inexpensive STPG pipe is used. Cost reduction is possible.

  Further, the temperature load is often increased when the bottom plate 5 and the side wall 7 are rigidly connected, but the configuration of the heater tubes 13 and 22 of the present embodiment for reducing the temperature load is particularly suitable in such a case. Can be applied. In addition, it is easy to secure the same frozen concrete thickness at the corner portion (haunch 6) of the bottom plate 5 and the side wall 7 by making the heater pipe away from the tank inner surface at the corner portion where the haunch 6 is located in the same manner as the others. Become.

  However, the present invention is not limited to this. For example, the specific positions of the heater tubes 13 and 22 are not limited to the above, and are determined according to the dimensions of the members of the bottom plate 5 and the side wall 7, the thickness of the heat insulating material, and the heat insulating performance. There may be some differences in temperature. Further, when the side wall thickness is thin, the heater pipe 13 of the side heater equipment may be embedded in the underground continuous wall 9. Furthermore, it is also possible to manage the position of the freezing line b by using a planar heating element instead of the heater tubes 13 and 22.

  Further, the position of the freezing line b is not limited to the above, and the distance from the inner surface of the tank housing is set to 2 m or less by reducing the piping interval of the heater pipes 13 and 22, for example, the separation distance is set to about 1 m. Is also possible. In addition, it is desirable to secure the thickness of frozen concrete at least about 1 to 2 m from the viewpoint of securing watertightness and airtightness by performing freeze-stopping.

  The shape of the heater tubes 13 and 22 is not particularly limited. For example, in the present embodiment, a double tube type is used for the heater tube 13, but a U-shaped tube type shown in a heater tube 13 ′ in FIG. 5 may be used.

  In this case, both ends of the heater tube 13 ′ are projected from the top of the side wall 7, and one end is connected to the header tube 11 on the supply side and the other end is connected to the header tube 15 on the recovery side. A plurality of heater tubes 13 'are arranged along the circumferential direction of the side wall 7 (corresponding to the left-right direction in FIG. 5) so that the distances D1 between the vertical tubes are substantially equal.

  Hereinafter, another example of the present invention will be described as second and third embodiments. The second and third embodiments will be described with respect to differences from the embodiments described so far, and the same points will be denoted by the same reference numerals in the drawings and the like, and description thereof will be omitted.

[Second Embodiment]
FIG. 6 is a view showing an underground tank structure 1a according to the second embodiment, and FIG. 7 is a view showing a heater pipe 13a of a side heater facility. The second embodiment differs from the first embodiment in that the heater pipe 13a of the side heater facility has a circumferential pipe 134 arranged in the circumferential direction of the tank housing.

  The heater tube 13a is a heater tube on the side of the tank housing, and is embedded in the vicinity of the outer boundary portion of the side wall 7 and arranged in a substantially spiral shape. More specifically, as shown in FIG. 7A, the heater pipe 13a has a plurality of upper and lower circumferential pipes 134, and the upper and lower circumferential pipes 134 are inclined with respect to the circumferential pipe 134 at an elevation. Connected in a single stroke by the inclined pipe 135. The distance between the upper and lower circumferential pipes 134 is adjusted to the distance between the inner and outer circumferential pipes 222 at the bottom of the tank housing.

  The lowermost and uppermost circumferential pipes 134 of the heater pipe 13a are connected to vertical pipes 133 and 136, respectively. These vertical pipes 133 and 136 protrude outward from the outer peripheral surface of the side wall 7 and form a closed flow path outside. A heating facility and a circulation pump (not shown) are provided in this flow path. In this embodiment, a heat medium is circulated through the heater pipe 13a in the side wall 7 using a heating facility or a circulation pump, and heat exchange is performed between the concrete on the side wall 7 and the heat medium in the heater pipe 13a.

  The pipe diameter and length of the heater pipe 13a are determined by design according to the capacity and flow rate of the circulation pump. In the present embodiment, a JIS standard 2B pipe is used as the heater pipe 13a and the length is about 1500 m at the maximum. As shown in FIG. 7B, the heater pipe 13a has a plurality of upper and lower stages depending on the height of the side wall 7. Buried in The construction method of the side wall 7 in which the heater tube 13a is embedded is substantially the same as in the first embodiment.

  As in the first embodiment, the heater tube 13a of the side heater equipment and the heater tube 22 of the bottom heater equipment are arranged along a line segment a similar to the inner surface shape of the tank housing as a whole, and from the inner surface of the tank housing. The separation distances to the heater tubes 13a and 22 are substantially the same. This separation distance is about 2.5 m, for example.

  Also in the present embodiment, in each heater facility, the heat medium having the same temperature is circulated through the heater tubes 13a and 22 and heat exchange is performed between the heat medium and the concrete of the side wall 7 and the bottom plate 5 to obtain the first As in the embodiment, the freezing line b is maintained and managed in the bottom plate 5 and the side wall 7, and the freezing line b as a whole is a line segment similar to the inner surface shape of the tank housing, and from the inner surface of the tank housing in the bottom plate 5 and the side wall 7. The separation distance to the freezing line b is made substantially the same. Thereby, the temperature load reduction effect similar to 1st Embodiment is acquired.

  In this embodiment, the heater pipes 13a and 22 of the side heater equipment and the bottom heater equipment have a similar annular structure, and the heater pipes 13a and 22 are separated from the inner surface of the tank housing, the pipe interval, the heat Since the medium temperature and the like are the same and have the same specifications, it is possible to easily prevent the freezing line b from coming off at the corner portions of the bottom plate 5 and the side wall 7. In the first embodiment, in order to prevent the freezing line b from coming out of the heater pipes 13 and 22 at the corner portion, the lower end of the heater pipe 13 of the side heater equipment is about 2.0 to 3.0 m, and the heater of the bottom heater equipment is used. Although it is necessary to bring the pipe 22 below the upper end, such waste is eliminated in the present embodiment. Further, the header tubes 11 and 15 as in the first embodiment are not required.

  In the present embodiment, the workability is improved by connecting the pipes 134 in the horizontal direction along the horizontal plane, and the pipes are connected by the diagonal pipe 135. It is good also as a shape arrangement.

  In this embodiment, the heater pipe 13a of the side heater equipment is a 2B pipe and the maximum length is 1500 m. However, the present invention is not limited to this, and the capacity of the circulation pump and the heat medium between both ends of the heater pipe 13a. It is determined in consideration of the temperature drop. For example, the heater tube 13a can be made thicker (for example, as a 3B tube), and the maximum length can be increased to about 2000 m.

  In addition, in the present embodiment, the heater tube 13a may be continuous with the heater tube 22 at the bottom of the tank housing. That is, as shown in FIG. 8, the outermost circumferential pipe 222 of the heater pipe 22 is connected to the lowermost circumferential pipe 134 of the heater pipe 13a on the side of the tank housing by an oblique pipe 135 or the like.

  Conventionally, the side heater equipment and the bottom heater equipment are generally provided on the side wall 7 and the bottom plate 5 as separate heaters, respectively, but in the example of FIG. Since it is continuous between the side walls 7, it becomes easier to align the separation distance from the inner surface of the tank housing to the freezing line b in the bottom plate 5 and the side walls 7. Further, it is possible to easily prevent the freezing line b from coming out at the corner portions of the bottom plate 5 and the side wall 7.

  In the example of FIGS. 7B and 8, the heater tube 13 a and the like are divided into a plurality of upper and lower stages due to the restriction of the flow path length. However, in the case of a small tank, FIG. 8) The heater tube 13a and the like in FIG. 8 can be realized as a single heater tube without dividing into blocks.

  Further, as shown in FIG. 9, both end portions of a plurality of circumferential pipes 138 in the upper and lower stages of the heater pipe 13 a ′ on the side of the tank housing can be connected to vertical pipes 137 and 139, respectively. As described above, the vertical pipes 137 and 139 protrude outward from the outer peripheral surface of the side wall 7 and form a closed flow path outside. Heating equipment and a circulation pump are arranged in this flow path.

  Since the heater pipe 13a has a long flow path length, the heater pipes 13a are arranged in a plurality of stages in the side wall 7 due to the restriction of the flow path length. However, the heater pipe 13a ′ in FIG. Therefore, if the necessary circumferential pipes 138 are attached to the vertical pipes 137 and 139, there is no need to install the heater pipes 13a ′ in a plurality of stages. The vertical pipes 137 and 139 have the same function as the header pipes 11 and 15 of the first embodiment, but have a length longer than that of the header pipes 11 and 15 that need to be arranged over the entire circumference of the tank. It can be shortened and the cost is low. When the heater pipe at the bottom of the tank casing is connected to the heater pipe 13a 'as in the example of FIG. 8, the lower ends of the vertical pipes 137 and 139 are extended to the plane center of the bottom slab 5, and What is necessary is just to connect the both ends of each circumferential piping of the heater pipe | tube of a bottom part.

[Third Embodiment]
FIG. 10 is a view showing an underground tank structure 1b according to the third embodiment. In the third embodiment, a heater pipe 32 continuous between the bottom plate 5 and the side wall 7 is provided, and the heater pipe 32 is piped in a substantially horizontal direction and a substantially vertical direction respectively at the bottom plate 5 and the side wall 7. Different from the second embodiment.

  The heater pipe 32 has a configuration in which a vertical pipe 321 in a substantially vertical direction and a horizontal pipe 322 in a substantially horizontal direction are connected by a connection pipe 323. For example, 2B pipes are used for these pipes. The vertical pipe 321 is a heater pipe on the side of the tank housing, and is embedded in the vicinity of the outer boundary of the side wall 7. The horizontal pipe 322 is a heater pipe at the bottom of the tank casing and is embedded in the upper part of the bottom plate 5. The connection pipe 323 has an inclination in the vertical plane along the haunch 6.

  The heater pipe 32 is disposed along a line segment a similar to the inner surface shape of the tank housing as a whole, and the distance from the inner surface of the tank housing to the heater tube 32 is substantially the same. This separation distance is about 2.5 m, for example. In this embodiment, after placing the heater tube 32 on the reinforcing bars and the cradle of the bottom plate 5 and the side wall 7, the bottom plate 5 and the side wall 7 in which the heater tube 32 is embedded are formed by placing concrete on the bottom plate 5 and the side wall 7. Can be built.

  FIG. 11 is a view showing the plane of the heater tube 32 in the same manner as FIG. Note that FIG. 11 shows only a quarter range in the circumferential direction of the plane of the bottom slab 5, but the other portions have the same shape.

  As shown in FIG. 11, the horizontal pipe 322 is substantially V-shaped or substantially U-shaped in plan view, and both ends thereof are connected to the vertical pipe 321 via the connection pipe 323. The upper parts of both vertical pipes 321 exit from the top of the side wall 7 and are connected to header pipes 31 and 33 (see FIG. 10), respectively. The header pipes 31 and 33 are arranged at the top of the side wall 7 in the circumferential direction of the tank housing.

In the present embodiment, the plurality of heater tubes 32 are arranged along the circumferential direction of the tank housing, and the distance D2 between the vertical pipes 321 is approximately equal to about 2.0 m, for example, about 1.5 to 2.0 m. Although the horizontal pipe 322 extends toward the plane center of the bottom slab 5, the position of the tip of the horizontal pipe 322 differs from the plane center of the bottom slab 5 in order to prevent the pipe from becoming too dense near the plane center of the bottom slab 5. It is shifted in such a way that r ₁ ~r _4.

  In the present embodiment, the heating medium and the circulation pump (not shown), the header pipe 31, the heater pipe 32, the header pipe 33, and the heating equipment are circulated in this order, and the concrete of the bottom plate 5 and the side wall 7 and the heater pipe 32 are circulated. By performing heat exchange with the internal heat medium, the freezing line b is maintained and managed in the bottom plate 5 and the side wall 7 in the same manner as in the first embodiment, and the freezing line b as a whole has the shape of the inner surface of the tank housing. The line segments are similar to each other, and the distance from the inner surface of the tank housing to the freezing line b in the bottom plate 5 and the side wall 7 is made substantially the same. Thereby, the temperature load reduction effect similar to 1st Embodiment is acquired.

  Also in the present embodiment, similarly to the example of FIG. 8, by using the heater tube 32 having the same specification that is continuous between the bottom plate 5 and the side wall 7, the bottom plate 5 and the side wall 7 can extend from the inner surface of the tank housing to the freezing line b. It is easier to align the separation distances. In addition, it is easy to align the separation distance of the freezing line b in the corner portion where the haunch 6 is located with the others, and in order to prevent the freezing line b from coming out of the heater tube in the corner portion, There is no waste of bringing the lower end of the pipe below the upper end of the heater pipe of the bottom heater equipment by about 2.0 to 3.0 m.

  Furthermore, in this embodiment, since the flow path length per heater tube is short and a long pipe is not required, a heater pipe 32 of about 2B pipe can be adopted, resulting in low cost.

  In this embodiment, the vertical pipe 321 of the heater pipe 32 is embedded in the side wall 7. However, as in the first embodiment, the vertical pipe 321 is embedded in the underground continuous wall 9 when the side wall thickness is thin. It is also possible to do. The heater pipe 32 is, for example, an STPG pipe, but may be a SUS pipe (stainless steel pipe) or a PL pipe.

  Further, the shape of the heater tube is not limited to the above example. For example, in the example of FIG. 12, the horizontal pipes 322a of the heater pipes 32a are substantially L-shaped, and a plurality of the horizontal pipes 322a are arranged along a predetermined radial direction (upper right direction in the example of the figure) from the plane center of the bottom plate 5. The distance D3 between the sides of the adjacent horizontal pipes 322a is substantially equal. On the other hand, in the example of FIG. 13, the horizontal pipes 322b of the heater pipes 32b are substantially linear, and a plurality of them are arranged in parallel with the intervals D3 being substantially equal.

  In the example of FIGS. 12 and 13, the temperature difference between the heater tubes 32a and 32b is reduced by making the flow of the heat medium of the adjacent heater tubes 32a and 32b face each other as indicated by arrows f1 and f2. be able to.

  In the example of FIGS. 12 and 13, the distance D3 is set to a maximum of 2.0 m, for example, about 1.5 to 2.0 m in accordance with the distance D2 between the vertical pipes 321. In order to match the distances D2 and D3, in these examples, the connection pipe 323 is bent in a plane with respect to the horizontal pipes 322a and 322b, and some of the heater pipes 32a and 32b are substantially L-shaped or substantially straight. No vertical horizontal pipes 322a and 322b are provided, and the lower ends of the vertical pipes 321 are formed in a substantially U shape (for example, the heater pipe 32a on the upper right in FIG. 12).

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1, 1a, 1b: Underground tank structure 3: Peripheral ground 4: Catchment layer 5: Bottom plate 6: Haunch 7: Side wall 8: Steel roof 9: Underground continuous walls 11, 15, 31, 33, 101, 105: Header pipes 13, 13 ′, 13a, 13a ′, 22, 32, 32a, 32b, 103, 201: heater pipe 41: reinforcing bar 131: inner pipe 132: outer pipe 133, 136, 137, 139, 221, 224, 321 : Vertical piping 134, 138, 222: Circumferential piping 135, 223: Diagonal piping 322, 322a, 322b: Horizontal piping 323: Connection piping

Claims (8)

An underground tank structure provided on the ground,
A tank housing including a bottom plate and side walls;
Freezing lines indicating the position where the 0 ℃ with the tank operating is Ri position near to a substantially same distance from the inner surface of the tank skeleton in the side wall and the bottom plate,
The position of the freezing line is managed by circulating a heat medium to the heater pipe on the side of the tank casing and the heater pipe on the bottom of the tank casing,
The heater tube at the side of the tank housing and the heater tube at the bottom of the tank housing are arranged at substantially the same distance from the inner surface of the tank housing,
The underground tank structure according to claim 1, wherein a heater pipe on a side of the tank casing is embedded in the side wall of the tank casing, and the freezing line is formed inside a heater pipe on the side of the tank casing . Underground tank structure according to claim 1 in which the heater tube side of said tank skeleton, a heater tube in the bottom of the tank precursor is characterized by continuous. The heater tube at the bottom of the tank housing is arranged in a substantially horizontal direction, and both ends are connected to the heater tube on the side of the tank housing,
The heater pipe on the side of the tank housing is arranged in a substantially vertical direction,
The tank skeleton bottom heater tube of the substantially V-shaped in plan, the underground tank structure according to claim 2, characterized in that it is arranged either in the form of a substantially L-shaped. A plurality of heater tubes at the bottom of the tank housing;
The underground tank structure according to claim 3, wherein the plurality of heater tubes at the bottom of the tank housing are arranged such that the positions of the bent tips are different distances from the plane center of the bottom plate. A heater tube side of said tank skeleton, a heater tube in the bottom of the tank skeleton is claimed in claim 1 or claim 2, characterized in that it comprises a pipe disposed along the circumferential direction of the tank skeleton Underground tank structure. Haunches are provided at the corners of the bottom plate and the side wall,
The pipe of the heater pipe at the bottom of the tank housing is arranged in a substantially spiral shape, and the pipe of the outer peripheral part is arranged along the inclination of the haunch so that the outer one is located above. The underground tank structure according to claim 5. The heater pipe at the bottom of the tank housing is embedded between the outer peripheral part of the bottom plate and the plane center of the bottom plate, and has a substantially same pipe diameter from the outer peripheral part to the plane center. The underground tank structure according to any one of claims 1 to 6.   The underground tank structure according to any one of claims 1 to 7, wherein the bottom plate and the side wall are rigidly connected.

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