JP2011162205A - Double-shell tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the leak detection reliability of a double-shell tank. <P>SOLUTION: The double-shell tank 10 includes an inner shell tank 80, a sheet-like member 90, a plurality of cord-like members 100, and an outer shell tank 110. The cord-like members 100 serve as gap holding members for holding a leak detection gap 120 between the inner and outer shell tanks 80 and 110, and are attached along the outer periphery of the inner shell tank 80 so as to be parallel to each other. A leak detection tube 130 is inserted into the leak detection gap 120. Each leak detection tube 130 is formed from a resin tube, and one end 132 extends to the bottom of the double-shell tank 10. The other end 134 of the each leak detection tube 130 is inserted into the flange 14 of the top of the tank and communicates with a narrow tube inserted into a liquid recovering portion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double shell tank, and more particularly to a double shell tank used as a tank for storing oil.

  For example, as a tank for storing oil liquid, there is a double shell tank in which a steel inner shell tank and a reinforced plastic outer shell tank are combined (for example, see Patent Document 1).

  In addition, in the case of double-shell tanks buried underground, it is configured to detect the presence or absence of oil leakage in the underground, and a thin resin film is interposed between the inner shell tank and the outer shell tank. A leak detection device is provided that forms a minute gap (space) and detects a change in pressure in the gap to detect the occurrence of pinholes in the inner shell tank or the outer shell tank.

  In addition, the resin film covers the surface of the inner shell tank to prevent the liquid plastic material from adhering to the surface of the inner shell tank when coating the reinforced plastic. It is a sheet-like member for forming a gap for leakage detection with the (outer shell tank). Therefore, the leak detection gap formed by the resin film is formed extremely thin.

JP 2009-113859 A

  However, in the structure of the above-mentioned double shell tank, the inner shell tank and the outer shell tank are caused by the shrinkage of the tank due to the ambient temperature change, the earth pressure due to the buried earth and sand, and the hydraulic pressure of the unloaded oil liquid. There is a problem that it is difficult to efficiently perform leak detection due to a change in pressure in the leak detection gap.

  Therefore, in view of the above circumstances, an object of the present invention is to provide a double shell tank that solves the above problems.

In order to solve the above problems, the present invention has the following means.
(1) The present invention comprises an inner shell tank,
A sheet-like member for forming a gap covering the outside of the inner shell tank;
In a double shell tank having an outer shell tank made of a reinforced plastic layer formed so as to cover the outside of the sheet-like member,
A plurality of string-like members are provided at predetermined intervals between the outside of the inner shell tank and the sheet member,
By attaching the sheet-like member to the outer side of the inner shell tank and the outer side of the string-like member, a leak detection gap corresponding to the thickness of the string-like member is provided between the outer side of the inner shell tank and the sheet-like member. It is characterized by forming.
(2) The said string-like member of this invention has many unevenness | corrugations on the surface, It is characterized by the above-mentioned.
(3) The string-like member of the present invention is formed in a wide belt shape, the back surface of the wide portion is in contact with the outside of the inner shell tank, and the sheet member is in contact with the front surface of the wide portion. It is characterized by being.
(4) In the present invention, a pressure detection tube is inserted into the leakage detection gap, and one end of the pressure detection tube is positioned between the bottom of the inner shell tank and the bottom of the outer shell tank. And the other end of the pressure detection tube is drawn out of the leak detection gap.

  According to the present invention, a plurality of string-like members are interposed at predetermined intervals between the outer side of the inner shell tank and the sheet member, thereby reducing the thickness of the string-like member between the inner shell tank and the sheet-like member. It is possible to form a gap for leak detection according to the inner shell tank, for example, by shrinkage due to temperature change around the tank, earth pressure due to buried earth and sand, or liquid pressure of unloaded oil liquid. It is possible to prevent the leak detection gap between the outer shell tank and the leak detection accuracy from being narrowed.

It is a front longitudinal cross-sectional view of one Example of the double shell tank by this invention. It is a side surface longitudinal cross-sectional view which follows the II line | wire in FIG. It is an expanded sectional view which expands and shows the A section in FIG. It is an expanded sectional view which expands and shows the B section in FIG. It is a front view which shows the state which attached the string-shaped member to the outer periphery of an inner shell tank. It is a perspective view which shows the state which attached the string-like member to the outer periphery of an inner shell tank. It is a longitudinal cross-sectional view which shows the structure of a double shell tank. FIG. 8 is a transverse sectional view taken along line II-II in FIG. 7. It is a perspective view which shows the structure of a leak detection tube. It is a longitudinal cross-sectional view which shows the cross-section of a leak detection tube. It is a longitudinal cross-sectional view which shows the state which the pressure acted on the leak detection tube.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a front longitudinal sectional view of an embodiment of a double shell tank according to the present invention. As shown in FIG. 1, the double-shell tank 10 is used as an underground tank buried in a base of a gas station, for example, and the surroundings are covered with earth and sand or concrete when installed in the basement. The double shell tank 10 is used as a storage tank for storing oil liquid, and is used to store fuel such as gasoline and light oil, or used engine oil (waste oil), for example. .

  Thus, when storing an oil liquid underground, the leak detection apparatus 20 which detects the presence or absence of the leak of the double shell tank 10 is provided. At the top of the double shell tank 10, a flange portion 12 to which the liquid level sensor 30 is attached and a flange portion 14 to which the leak detection device 20 is attached are provided.

  The leak detection device 20 and the liquid level sensor 30 are accommodated in a manhole 40 formed above the double shell tank 10 and are installed in a ground office 50 through signal lines 41 to 43. A detection signal is output to 60. The display device 60 is composed of, for example, a liquid crystal monitor, and performs display according to the input leakage detection signal and liquid level detection signal to notify the staff at the gas station.

  The liquid level sensor 30 measures the liquid level height position of the oil liquid stored in the double shell tank 10 and outputs a detection signal corresponding to the measured liquid level height position. The display 60 calculates and displays the storage amount from the height position of the liquid level based on the detection signal from the liquid level sensor 30.

  Further, the leak detection device 20 includes a liquid recovery unit 22 that recovers liquid (oil liquid or groundwater) leaked from the double shell tank 10, a liquid detection sensor 24 provided in the liquid recovery unit 22, and a liquid recovery unit 22. A window 26 that allows the inside to be visually observed, a drain cock 28 provided at a lower portion of the liquid recovery unit 22, and a pressure sensor 70 are provided.

  The liquid recovery unit 22 communicates with a leakage detection gap of the double shell tank 10 through a leak detection tube described later. A pinhole (small hole) is generated in the inner shell tank 80, and the inner portion of the inner shell tank 80 is increased. When the oil liquid flows into the leak detection gap, or when a pinhole (small hole) is generated in the outer shell tank 110 and the groundwater outside the outer shell tank 110 flows into the leak detection gap, the inflowed liquid Is configured to accumulate inside. The liquid detection sensor 24 outputs a detection signal to the display 60 when a predetermined amount of liquid has accumulated in the liquid recovery unit 22 (the liquid in the liquid recovery unit 22 has reached a predetermined height position).

  Further, the liquid staying in the liquid recovery unit 22 can be extracted by opening the drain cock 28. Further, by connecting the drain cock 28 and the suction port of the vacuum pump with a pressure hose, the leakage detection gap can be evacuated via the liquid recovery unit 22 and a leakage detection tube described later, and the liquid Continuous recovery is possible.

  The pressure sensor 70 is connected to the liquid recovery part 22 so as to detect the pressure of the liquid recovery part 22 communicated with the leakage detection gap of the double shell tank 10. Further, when a pinhole (small hole) is generated in the inner shell tank 80 and the oil (or gas) in the inner shell tank 80 flows into the leakage detection gap, or a pinhole (small hole) is formed in the outer shell tank 110. When groundwater (or gas) outside the outer shell tank 110 flows into the leakage detection gap, the pressure of the liquid recovery unit 22 increases due to the inflow. Therefore, the pressure sensor 70 can detect a leak in the double shell tank 10 by detecting a pressure change of the liquid recovery unit 22 in the leak detection gap of the vacuum shelled double shell tank 10. .

  The indicator 60 displays the occurrence of leakage in the double shell tank 10 based on the detection signal output from the liquid detection sensor 24 or the pressure sensor 70 and notifies the staff at the gas station.

  Further, since the liquid recovery part 22 is provided with the window 26 at the upper part, the clerk can visually confirm the inside of the liquid recovery part 22 by opening the lid 44 of the manhole 40. In the liquid recovery unit 22, an end of a leak detection tube, which will be described later, stands up to a predetermined height position so that the liquid (oil liquid or groundwater) discharged from the leak detection tube does not flow backward due to pressure fluctuations. It is configured.

  Further, since the capacity of the liquid recovery unit 22 that can store leaked liquid is set according to the total volume of the leakage detection gap of the double shell tank 10, for example, the oil liquid storage capacity of the double shell tank 10 is 2KL. -10 KL, which is selectively set as appropriate. That is, when a pinhole (small hole) due to corrosion occurs in the leak detection gap of the evacuated double-shell tank 10, fluid (gas, oil or groundwater) enters the leak detection gap and is described later. The pressure of the liquid recovery part 22 communicated with the leak detection gap is increased via the leak detection tube. For this reason, in the present embodiment, for example, when a pinhole is generated at the bottom of the inner shell tank 80, when the pressure in the inner shell tank 80 and the pressure in the liquid recovery portion 22 are balanced, leakage detection is performed from the pinhole. The movement of the oil liquid to the liquid recovery part 22 through the gap for use is stopped, but the capacity of the liquid recovery part 22 to accommodate the leaked liquid and the degree of vacuum so that the oil liquid reaches the liquid recovery part 22 Is set.

  Here, the structure of the double shell tank 10 will be described. FIG. 2 is a side longitudinal sectional view taken along line II in FIG. FIG. 3 is an enlarged cross-sectional view showing an A portion in FIG. FIG. 4 is an enlarged cross-sectional view showing the portion B in FIG.

  As shown in FIGS. 2 to 4, the double shell tank 10 includes an inner shell tank 80, a sheet-like member 90, a plurality of string-like members 100, and an outer shell tank 110.

  The inner shell tank 80 is a tank made of steel (or a resin such as fiber reinforced plastic (FRP)), and a liquid phase portion LA in which an internal space stores an oil liquid and a gas phase in which vapor stays. Divided into part LB.

  The sheet-like member 90 is made of a resin film that is attached so as to cover the inner shell tank 80 and the surfaces of the plurality of string-like members 100, and forms a leak detection gap (leakage detection space) 120 corresponding to the thickness dimension. It functions as a partition wall. Further, the sheet-like member 90 is not limited to the resin film, and may be a flat sheet such as paper or cloth.

  The plurality of string-like members 100 are gap holding members for securing a leakage detection gap 120 between the inner shell tank 80 and the outer shell tank 110, and are attached in parallel along the outer periphery of the inner shell tank 80. It has been. The string-like member 100 is made of, for example, a belt-shaped resin tape having a lateral width of about 1 cm to 2 cm, the back surface of the wide portion abuts the outside of the inner shell tank 80, and the front surface of the wide portion is a sheet shape. It contacts the inside of the member 90.

  Further, since the string-like member 100 has a shape having a large number of irregularities on the surface, it does not adhere to the outside of the inner shell tank 80, and always forms a minute gap with the outside of the inner shell tank 80. In addition, when the string-like member 100 is made of a resin tape, irregularities of a certain size are formed in a uniform pattern, and when weaving fibers, irregularities of different sizes are irregular patterns. Formed with.

  The outer shell tank 110 is made of fiber reinforced plastic (FRP) and is formed so as to cover the outside of the sheet-like member 90. The outer shell tank 110 is formed by applying a liquefied fiber reinforced plastic to the outside of the sheet-like member 90, and then drying until the solvent contained in the fiber reinforced plastic evaporates and solidifies. There is a method or a method of sticking a fiber-reinforced plastic sheet solidified in advance to the outside of the sheet-like member 90.

  Further, the outer shell tank 110 has a position of the maximum liquid level height Hmax corresponding to the maximum storage amount of the double shell tank 10, and is formed near the top portion above the maximum liquid level height Hmax. Not. A seal layer 160 made of a resin material or the like is formed on the surface of the inner shell tank 80 above the maximum liquid level height Hmax.

  As shown in FIG. 4, a leak detection tube 130 is inserted into the leak detection gap 120. The leak detection tube 130 is made of a resin tube, and one end (leakage liquid suction port) 132 extends to the bottom of the double shell tank 10. In the double shell tank 10, the liquid flowing into the leak detection gap 120 from the pinhole generated in the inner shell tank 80 or the outer shell tank 110 accumulates at the bottom of the leak detection gap 120. Therefore, in the present embodiment, the tip of the leak detection tube 130 is inserted to the bottom of the tank (the bottom of the leak detection gap 120), so that the liquid flowing into the leak detection gap 120 is transferred to the liquid recovery section. 22 is configured to be easily collected.

  The other end (leakage liquid discharge port) 134 of the leak detection tube 130 is inserted into the flange portion 14 through the seal layer 160 at the top of the tank and communicated with the narrow tube 21 inserted in the liquid recovery portion 22. Therefore, the leak detection tube 130 extracts the liquid (oil liquid or groundwater) flowing into the leak detection gap 120 from the thin tube 21 to the liquid recovery unit 22, and the fluid flowing into the leak detection gap 120 is a gas. In that case, the pressure in the liquid recovery unit 22 is increased.

  As described above, when the liquid leaked into the liquid recovery unit 22 is injected, a detection signal is output from the liquid detection sensor 24 described above, and the gas flows into the leak detection gap 120 and the liquid recovery unit 22 When the pressure rises, a detection signal is output from the pressure sensor 70, and a leak detection of the double shell tank 10 is displayed on the display 60.

  Here, the attachment state of the string-like member 100 will be described. FIG. 5 is a front view showing a state in which a string-like member is attached to the outer periphery of the inner shell tank. FIG. 6 is a perspective view showing a state in which a string-like member is attached to the outer periphery of the inner shell tank. FIG. 7 is a longitudinal sectional view showing the structure of the double shell tank. FIG. 8 is a transverse sectional view taken along line II-II in FIG.

  As shown in FIGS. 5 to 8, in the manufacturing process of the double shell tank 10, after the steel plate is processed into a cylindrical shape and the inner shell tank 80 is manufactured, a plurality of string-like members are formed on the outer periphery of the inner shell tank 80. 100 are mounted in parallel. The string-like member 100 is made of a resin tape or the like. For example, only the upper end is attached to the outer periphery of the inner shell tank 80. Note that the attachment pattern and fixing method of the string-like member 100 may be arbitrarily changed.

  Further, the plurality of string-like members 100 may be arranged so as to hang down from both sides of the inner shell tank 80. Furthermore, the string-like member 100 is also arranged at the bottom of the inner shell tank 80 so as to extend in the tank longitudinal direction, and is provided so as to intersect with the string-like member 100 along the other outer periphery.

  The plurality of string-like members 100 are disposed so that the sheet-like member 90 covers the outside of the inner shell tank 80 and is held in an attached state in contact with the outside of the inner shell tank 80.

  As shown in FIG. 8, when the sheet-like member 90 is disposed outside the inner shell tank 80, a plurality of string-like members 100 are latticed between the outer side of the inner shell tank 80 and the inner side of the sheet-like member 90. Therefore, a gap corresponding to the thickness of the string-like member 100 is formed as a leakage detection gap 120 between the outer side of the inner shell tank 80 and the inner side of the sheet-like member 90.

  Therefore, by attaching a plurality of string-like members 100 to the outside of the inner shell tank 80, the tank shrinks due to changes in the surrounding temperature, the earth pressure due to buried earth and sand, and the hydraulic pressure of the unloaded oil liquid. Even when the gap between the inner shell tank 80 and the outer shell tank is narrowed, the leak detection gap 120 can be secured, and the leak detection device 20 detects the leakage of the inner shell tank 80 and the outer shell tank 110. The accuracy can be increased.

  Further, when the double shell tank 10 is used as an underground tank, the maximum storage amount of the oil liquid is determined, and the position of the maximum liquid level height Hmax is defined according to the maximum storage amount. For this reason, the leakage detection gap 120 and the outer shell tank 110 need only be provided at the position of the maximum liquid level height Hmax, and therefore do not need to be provided up to the tank top portion that is the peripheral portion of the flange portion 14. Therefore, the upper ends of the plurality of string-like members 100 only need to reach the position of the maximum liquid level height Hmax.

  Here, the structure of the leak detection tube 130 will be described. FIG. 9A is a perspective view showing the structure of a leak detection tube. FIG. 9B is a longitudinal sectional view showing a sectional structure of the leak detection tube. FIG. 9C is a longitudinal sectional view showing a state in which pressure is applied to the leak detection tube.

  As shown in FIGS. 9A and 9B, in the leak detection tube 130, a small diameter thin wire 150 is inserted into a hollow portion 140 of a resin tube having relatively flexibility. The thin wire 150 is made of, for example, a metal wire having a circular cross-sectional shape in the radial direction or a resin wire material having rigidity, and has strength to withstand pressure from the outside.

  Therefore, as shown in FIG. 9C, even if the outside of the leak detection tube 130 is compressed into an elliptical shape, the thin wire 150 inserted into the hollow portion 140 does not deform, so that there is a leak detection space in the hollow portion 140 for a crescent moon. It remains as a passage with a cross-section. That is, the leak detection tube 130 inserted into the leak detection gap 120 is formed by the inner shell tank due to the shrinkage of the tank due to the ambient temperature change, the earth pressure due to the buried earth and sand, or the hydraulic pressure of the unloaded oil liquid. Even when the leakage detection gap 120 between the outer shell 80 and the outer shell tank 110 is narrowed, the hollow portion 140 of the leakage detection tube 130 is not blocked.

  Therefore, even if some pressure (internal pressure increase due to expansion of the inner shell tank 80 or external pressure due to contraction of the outer shell tank 110 due to earth pressure) acts on the leak detection tube 130, a space is always formed inside the leak detection tube 130. Thus, a flow path for the leaked liquid and an air suction passage for evacuation are ensured. As a result, the leakage detection tube 130 is prevented from closing and the leakage detection accuracy of the inner shell tank 80 and the outer shell tank 110 by the leakage detection device 20 can be maintained.

  Needless to say, the cross-sectional shape of the thin wire 150 may be a shape other than a circle (for example, a square, a hexagon, etc.).

  In the above-described embodiment, a double shell tank used as an underground tank of a gas station has been described as an example. However, the present invention is not limited to this, and the present invention has, for example, a number of vehicles such as trucks, buses, taxis, The present invention can be applied to a case where it is used as an oil supply facility of a company, or can be applied to an underground tank installed in an automobile maintenance company or an automobile sales company that performs oil exchange.

DESCRIPTION OF SYMBOLS 10 Double shell tanks 12 and 14 Flange part 20 Leak detection device 22 Liquid recovery part 24 Liquid detection sensor 26 Window 28 Drain cock 30 Liquid level sensor 40 Manhole 41-43 Signal line 60 Display 70 Pressure sensor 80 Inner shell tank 90 Sheet -Like member 100 String-like member 110 Outer shell tank 120 Leakage detection gap 130 Leakage detection tube 132 One end 134 The other end 140 Hollow portion 150 Thin wire

Claims (4)

An inner shell tank,
A sheet-like member for forming a gap covering the outside of the inner shell tank;
In a double shell tank having an outer shell tank made of a reinforced plastic layer formed so as to cover the outside of the sheet-like member,
A plurality of string-like members are provided at predetermined intervals between the outside of the inner shell tank and the sheet member,
By attaching the sheet-like member to the outer side of the inner shell tank and the outer side of the string-like member, a leak detection gap corresponding to the thickness of the string-like member is provided between the outer side of the inner shell tank and the sheet-like member. A double-shell tank characterized by forming.   The double-shell tank according to claim 1, wherein the string-like member has a large number of irregularities on a surface thereof.   The string-like member is formed in a wide belt shape, the back surface of the wide portion is in contact with the outside of the inner shell tank, and the sheet member is in contact with the front surface of the wide portion. The double shell tank according to claim 1 or 2. A pressure detection tube is inserted into the leakage detection gap, and one end of the pressure detection tube is disposed between the bottom of the inner shell tank and the bottom of the outer shell tank, and the pressure detection tube The double-shell tank according to any one of claims 1 to 3, wherein the other end of the tube is pulled out of the leakage detection gap.

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