JP2016043957A - Float roof type tank grounding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a float roof type tank grounding device which can detect cut-off of a conductor.SOLUTION: A ferrite magnet 54 contacts by self-weight to a lead switch 72. When a conductor 23 is cut, the conductor 23 is wound to a drum by energization force of a power spring. At the time, a cut-end part of the conductor 23 which is wound to the drum, flip ups a metal plate 52 and the ferrite magnet 54, thereby distance between the lead switch 72 and the ferrite magnet 54 is maintained, so that, two contact parts of the lead switch 72 are opened.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a grounding device for a floating roof type tank.

  As a background art in this technical field, there is JP 2008-213886 A (Patent Document 1). In this publication, “a tank body 2 for storing the liquid 1, a floating roof 3 that is floated on the liquid surface in the tank body, and a sloshing suppression that is provided on the floating roof and suppresses the sloshing of the liquid. The sloshing suppression device 5 includes a first suppression member 51 disposed at the bottom of the floating roof 3 in a form along the liquid level of the liquid 1 and a form suspended from the floating roof 3 in the liquid. The first suppressing member 51 and the second suppressing member 52 are formed of a porous material that generates a fluid resistance necessary for suppressing the sloshing of the liquid by relative movement with the liquid 1. (See summary).

Japanese Patent Laid-Open No. 2008-213886

  Patent Document 1 describes a floating roof tank. However, the floating roof type tank has a gap between the floating roof and the side wall of the tank body, and its electrical contact is not guaranteed. For this reason, when the two are not in contact with each other, a spark may be generated between the two due to static electricity or the like. Therefore, it is conceivable to electrically connect the floating roof and the tank body with a long conductor that can be pulled out and stored from the housing in accordance with the height of the floating roof.

However, the floating roof does not necessarily go down little by little as the oil in the tank body decreases, and the floating roof may suddenly come off from the state of being caught on the side wall of the tank body, and may drop rapidly. In addition, it may shake tremendously when an earthquake occurs. For this reason, the long conductor may be cut off due to these reasons, and such a situation should be detected quickly.
Then, this invention makes it a subject to provide the grounding apparatus for floating roof type tanks which can detect the cutting | disconnection of a conductor.

  In order to solve the above-described problem, an embodiment of the present invention includes a long conductor that electrically connects a container body of a floating roof tank and the floating roof, and a detection unit that detects cutting of the conductor. Have.

ADVANTAGE OF THE INVENTION According to this invention, the grounding apparatus for floating roof type tanks which can detect the cutting | disconnection of an electric conductor can be provided.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

FIG. 1 is an explanatory view showing an installation example of a grounding device for a floating roof type tank according to an embodiment of the present invention to the floating roof type tank. FIG. 2 is a side view of a floating roof tank grounding device according to an embodiment of the present invention. FIG. 3 is a perspective view of a floating roof tank grounding device according to an embodiment of the present invention. FIG. 4 is an exploded perspective view of a floating roof tank grounding device according to an embodiment of the present invention. FIG. 5 is an enlarged longitudinal sectional view of the entrance / exit portion of the conductor of the grounding device for a floating roof type tank according to one embodiment of the present invention. FIG. 6 is a perspective view of the detection unit of the floating roof tank grounding device according to the embodiment of the present invention. FIG. 7 is an explanatory view for explaining the operation of the floating roof tank grounding device according to one embodiment of the present invention. FIG. 8 is an explanatory diagram for explaining the operation of the floating roof tank grounding device according to one embodiment of the present invention. (A) shows the state where the reed switch and the ferrite magnet are in contact, and (b) shows the state where the reed switch and the ferrite magnet are separated. FIG. 9 is an explanatory diagram for explaining the operation of the floating roof tank grounding device according to one embodiment of the present invention. FIG. 10 is a circuit diagram of a detection circuit using a reed switch of a floating roof tank grounding device according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of installation of the floating roof tank grounding device 10 according to the present embodiment on the floating roof tank 100.

  First, as shown in FIG. 1, a floating roof tank 100 for storing a liquid such as crude oil outdoors includes a floating roof 102 provided with a floating 101 called a pontoon, and a container body 103. The floating roof 102 moves up and down as the crude oil or the like increases or decreases.

  Because of such a configuration, there is a gap between the side wall 104 of the cylindrical container body 103 in which crude oil or the like is stored and the floating roof 102 that floats on the crude oil or the like inside the container body 103. The electrical contact between the two is not always guaranteed. Therefore, when the floating roof 102 is charged by static electricity, when the side wall 104 and the floating roof 102 come into contact with each other, a spark may be generated due to discharge of the charged static electricity. Also, when a lightning strike occurs on the floating roof, there is a risk that a spark discharge will occur between the side wall 104 and the floating roof 102 due to a lightning surge.

In order to prevent the occurrence of such sparks, the floating roof 102 and the side wall 104 are electrically connected while corresponding to the vertical movement of the floating roof 102 due to increase or decrease of crude oil or the like, and both are maintained at the same potential. A grounding device 10 for a floating roof type tank is required as a device for this purpose.
However, since the floating roof tank 100 is installed outdoors, the grounding device 10 for the floating roof tank is always exposed to wind and rain, and is exposed to the risk of damage due to corrosion caused by the attachment of rainwater and various foreign substances. It is.

In particular, some crude oil in the floating roof tank 100 contains hydrogen sulfide depending on the production area. Hydrogen sulfide (H ₂ S) has a specific gravity of 1.1905 and is a gas heavier than air, and an aqueous solution (hydrosulfuric acid) in which hydrogen sulfide is dissolved in water is hydrogen sulfide ions (HS ⁻ ) and hydrogen ions (H ⁺ ). And is weakly acidic. On the other hand, since the floating roof tank 100 is installed outdoors, the hydrogen sulfide easily dissolves in the rainwater to produce an aqueous solution of hydrogen sulfide. Since the floating roof tank grounding device 10 uses metal or the like to ensure conductivity, the floating roof tank 100 is exposed to a risk of being corroded by the aqueous solution of hydrogen sulfide. There is a bug.

Therefore, hereinafter, the floating roof tank grounding device 10 that is protected from such deterioration as corrosion and can be used for a long time will be described.
2 is a side view of the floating roof tank grounding device 10 according to the present embodiment, FIG. 3 is a perspective view thereof, and FIG. 4 is an exploded perspective view thereof. 2 and 3 show the X, Y, and Z directions. The X direction is the vertical vertical direction when the floating roof tank grounding device 10 is installed as shown in FIG. 1, the Y direction is the direction perpendicular to the X direction and the page of FIG. 2, and the Z direction is perpendicular to the X direction and the Y direction. Direction.

  As shown in FIGS. 2 to 4, the floating roof tank grounding device 10 includes a box-shaped casing 11. As shown in FIG. 4, the casing 11 includes a casing 11a and a casing 11b. One end of a shaft 13 is fixed to the inner wall surface 12 of the housing 11b, and the other end side of the shaft 13 extends in the Y direction toward the front side of the sheet of FIG. A drum 15 is attached to the shaft 13 via a pair of bearing mechanisms 14 so as to be rotatable forward and backward in the circumferential direction. The drum 15 includes a disk 16 attached to the bearing mechanism 14 and a reel-shaped frame body 17 formed on the outer periphery of the disk 16. An inner peripheral portion 18 of the drum 15 surrounded by the disc 16 and the frame body 17 forms a space.

  A mainspring spring 21 serving as a biasing member is provided in the inner peripheral portion 18. Near the frame 17 of the disc 16 of the drum 15, a pin 22 is formed extending in the Y direction toward the front side of the sheet of FIG. 2. The spiral outermost end of the mainspring spring 21 is fixed to the pin 22, and the innermost end is fixed to the shaft 13. A circular lid 20 (FIG. 4) is attached to the inner peripheral portion 18 in which the mainspring 21 is accommodated. Reference numeral 26 denotes a shaft slip-off preventing member such as the drum 15. A long conductor 23 is wound around a reel-shaped portion of the frame body 17. Below one X direction at both ends in the Z direction of the frame body 17, an entrance / exit 24 through which the conductor 23 enters and exits the inside and outside of the housing 11 is formed in the housing 11 (the entrance / exit plate 28 attached to the housing 11). . Thereby, the mainspring spring 21 biases the drum 15 in the direction in which the conductor 23 is wound up by the frame body 17 of the drum 15.

  A connecting member 31 for connecting the leading end portion 25 to the upper portion 105 (FIG. 1) of the floating roof 102 of the floating roof type tank 100 is provided at the leading end portion 25 on the pulling side from the entrance / exit 24 of the conductor 23. Yes. Further, a fixing member 32 for fixing the floating roof tank grounding device 10 to the side wall 104 (FIG. 1) of the floating roof tank 100 is provided on the outer wall surface 19 of the housing 11.

  The drum 15 is made of metal and is electrically connected to the housing 11 made of metal (such as a stainless steel plate such as SUS304) via the bearing mechanism 14. On the other hand, the mainspring 21 is also made of metal such as spring steel or stainless steel, and is electrically connected to the drum 15 and the pin 22. Therefore, from the front end portion 25 (connecting member 31) of the conductor 23 to the housing 11 (fixing member 32), an electrical path is formed in which each member formed of a conductor is connected. Therefore, if the connection member 31 is connected to the floating roof 102 and the fixing member 32 is fixed to the side wall 104 of the floating roof tank 100, the floating roof 102 and the side wall 104 are connected via the conductor 23 drawn from the housing 11. Are electrically connected.

Further, the drum 15, the bearing mechanism 14 that supports the drum 15, and the electrical connection path of the housing 11, the drum 15, the pin 22, and the mainspring spring 21, are electrically connected to the housing 11 by the pin 22. The path to be connected is electrically connected in parallel. This contributes to the reduction of electrical resistance and the redundancy of the connection path when the connection is temporarily unstable due to poor contact.
Therefore, the floating roof 102 and the side wall 104 are electrically connected by the floating roof tank grounding device 10, and both are maintained at the same potential. Therefore, it is possible to prevent the occurrence of a spark due to the static electricity or the lightning surge between the floating roof 102 and the side wall 104.

In addition, if the crude oil in the container body 103 decreases and the position of the floating roof 102 decreases, the conductor 23 is pulled out from the housing 11 against the urging force of the mainspring spring 21 due to the weight of the floating roof 102. When the crude oil in the container body 103 increases and the position of the floating roof 102 rises, the drum 15 winds up the conductor 23 by the urging force of the mainspring spring 21. Therefore, since the length of the conductor 23 drawn from the housing 11 varies corresponding to the variation in the height of the floating roof 102, the floating roof 102 and the side wall 104 are not affected by the variation in the height of the floating roof 102. Are always electrically connected in the shortest distance in which the conductor 23 is stretched in a straight line.
As shown in FIGS. 2 to 4, the mainspring spring 21 is surrounded by the disc 16, the frame body 17, and the lid body 20, and is provided in the inner peripheral portion 18 of the sealed drum 15. In addition, the entire periphery of the drum 15 is covered with the housing 11 and is substantially sealed except for the entrance / exit 24.

  Thus, the mainspring spring 21 is housed in the inner peripheral portion 18 of the drum 15 surrounded by the disc 16, the frame body 17, and the lid body 20 and is protected by the drum 15, and further, the outer side of the mainspring spring 21 is disposed on the casing 11. Covered with double protection. Therefore, the mainspring spring 21 is protected from intrusion of external rainwater and foreign matter, and is protected from deterioration such as corrosion due to an aqueous solution of hydrogen sulfide and can be used for a long time.

  FIG. 5 is an enlarged vertical sectional view of the entrance / exit 24 portion. As shown in FIGS. 4 and 5, a guide plate 42 serving as a pair of foreign matter removing members that sandwich the conductor 23 is provided at the entrance / exit 24 portion on the lower surface 41 side of the housing 11. Each guide plate 42 is in contact with both surfaces of the conductor 23 wound by the drum 15 and removes foreign matters on the surface of the conductor 23. As a result, when the drum 15 winds up the conductor 23, the guide plate 42 drains rainwater adhering to the conductor 23 and removes the foreign matter so as not to enter the housing 11. As the material of the guide plate 42, a fluororesin having low friction and excellent wear resistance, an inexpensive polyacetal resin, or the like is preferable. The entrance / exit 24 is formed in an entrance / exit plate 28 in which the slit-like entrance / exit 24 is formed. The entrance / exit plate 28 is bolted to a rectangular entrance / exit portion 46 formed in the lower surface 41 of the housing 11. . A pair of guide plates 42 are bolted to the entrance / exit plate 28.

In this case, the bolt holes to be bolted are elongated holes, and when the resin guide plate 42 is worn, the interval between the guide plates 42 can be adjusted. For this reason, the space between the pair of guide plates 42 is widened due to wear, and draining and removal of foreign matter are not hindered.
As described above, the guide plate 42 prevents rainwater and foreign matter from entering the housing 11, so that the members such as the drum 15 and the mainspring spring 21 in the housing are deteriorated by corrosion due to an aqueous solution of hydrogen sulfide. Protects from long-term use.

  By the way, the floating roof 102 is not necessarily lowered little by little as the crude oil or the like in the container body 103 decreases, but may suddenly come off from the state of being caught on the side wall 104 of the container body 103 and may fall rapidly. In addition, it may shake tremendously when an earthquake occurs. For this reason, the long conductor 23 may be cut off due to these reasons, and it is desirable to detect such a situation quickly. Therefore, in this embodiment, as shown in FIGS. 2 to 4, a detection unit 51 is provided. Below, the detection part 51 is demonstrated in detail.

As shown in FIGS. 2 to 4, the detection unit 51 is provided in the housing 11 so as to be positioned above the drum 15.
FIG. 6 is a perspective view of the detection unit 51. The detection unit 51 is a non-magnetic and corrosion-resistant material. For example, the detection unit 51 is made of SUS304 or the like, and is formed by attaching a ferrite magnet 54 to the tip 53 of a metal plate 52 bent in an L shape. A body 55 is provided. The bracket 61 has a central portion 62 bent into a convex shape, and both ends 63 are attached to the inner wall surface 12 (FIGS. 2 to 4) of the housing 11b. The base end portion 56 of the detection body 55 is inserted into a portion of the central portion 62 of the bracket 61 that is bent in a convex shape, and is prevented from coming off by an overhang portion 57 that protrudes from the base end portion 56. There is sufficient play in inserting the base end portion 56 of the detection body 55 into the central portion 62 of the bracket 61, so that the distal end portion 53 of the metal plate 52 can move up and down to some extent.

Further, a base 71 (FIG. 6) made of SUS304, which is a corrosion-resistant, nonmagnetic metal, is fixed to the housing 11b (FIG. 4). A main body 73 of the reed switch 72 is fixed on the base 71 with an adhesive or the like. The ferromagnetic lead of the reed switch 72 is soldered to the signal line 74 (reference numeral 75 indicates a soldered connection portion). And the ferrite magnet 54 of the front-end | tip part 53 of the metal plate 52 is located above the main body 73 of the reed switch 72. Usually, the detection body 55 is inclined downward, and the ferrite magnet 54 is reed by its own weight. 72 is in contact with the main body 73.
Below the detection body 55, the conductor 23 wound around the drum 15 is positioned such that its longitudinal direction is substantially orthogonal to the longitudinal direction of the metal plate 52.

The reed switch 72 including the solder connection portion 75 with the signal line 74 is molded with acrylic resin or epoxy resin, or coated by coating or dipping, etc., so that moisture can enter or corrosive atmosphere. Can be cut off.
The metal plate 52 can also be reduced in weight by using anodized aluminum, phosphor bronze thin plate, resin material, wire-like material, or the like.

  Next, the operation of the detection unit 51 will be described. With the above configuration, in the floating roof tank grounding device 10 installed as shown in FIG. 1, if the conductor 23 is cut halfway, the drum 15 causes the conductor 23 to be pulled by the urging force of the mainspring spring 21. It will be wound up. At this time, as shown in FIG. 7, the cut end portion (cut portion) 23a of the conductor 23 is lifted by an elastic force more than the conductor 23 wound around the drum 15, and the cut portion 23a. , The metal plate 52, and consequently the ferrite magnet 54, jumps up for a moment (in the direction of arrow “a” in FIG. 6) to take a distance between the reed switch 72 and the ferrite magnet 54.

  As described above, when the detection body 55 is inclined downward and the ferrite magnet 54 is in contact with the main body 73 of the reed switch 72 by its own weight, as shown in FIG. The two contact portions 73b in the glass tube 73a are closed. As is well known, the ferrite magnet 54 in contact with the main body 73 of the reed switch 72 applies a magnetic field in the axial direction of the signal line 74, thereby magnetizing the signal line 74 and closing the two contact portions 73b. It is.

However, as described above, when the cut portion 23a passes under the detection unit 51, the metal plate 52 and eventually the ferrite magnet 54 are sprung up, and as shown in FIG. When the distance from the magnet 54 is taken, the two contact portions 73b are opened. As described above, when the reed switch 72 is opened, the disconnection of the conductor 23 can be detected.
As shown in FIG. 9, even if the cut portion 23 a is curled, the metal plate 52, and consequently the ferrite magnet 54, can be flipped up to keep the distance between the reed switch 72 and the ferrite magnet 54. .

  FIG. 10 is a circuit diagram of a detection circuit using the reed switch 72. A reed switch 72, a relay contact 82a, and a relay main body 82b connected in series are connected to the power source 81. A set switch 83 is connected in parallel to the relay contact 82a. Further, a lamp 84 and a relay contact 82 c connected in series are connected to the power source 81.

As described above, since the reed switch 72 is normally closed, when the set switch 83 is turned ON, the relay body 82b operates to close the relay contacts 82a and 82c, and the relay contacts 82a and 82c are closed. Self-holding. At this time, the lamp 84 is lit. However, when the cut portion 23a jumps up the metal plate 52 and eventually the ferrite magnet 54 for a moment due to the cutting of the conductor 23, the reed switch 72 is opened and the energization to the relay body 82b is cut off, and the relay contacts 82a and 82c are closed. Self-holding of state is released. As a result, the lamp 84 is extinguished, and the fact that the conductor 23 is cut can be notified to the surroundings.
In addition, it is desirable to install about 4 to 6 floating roof type tank grounding devices 10 in one floating roof type tank 100 as shown in FIG. Further, circuit elements other than the reed switch 72 of the circuit of FIG. 10 may be installed at a position where there is no influence of corrosive gas, and the lamp 84 may be installed on the ground so that the abnormality can be easily checked. desirable.

According to the floating roof tank grounding device 10 of the present embodiment described above, even if the conductor 23 is cut when it is installed in the state of FIG. 1, the detection unit 51 detects the fact of the cutting. can do.
The detection unit 51 uses a reed switch 72 as a switch for detecting the disconnection of the conductor 23. Since the reed switch 72 encloses two contact portions 73b in a glass tube 73a enclosing an inert gas, it is not easily corroded by the hydrogen sulfide or the like. In addition, there is no danger of causing a flammable explosion even in a flammable gas environment.
Furthermore, since the detection unit 51 uses the ferrite magnet 54 as a magnet, it is not easily corroded by the hydrogen sulfide or the like.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

10 Grounding device for floating roof type tank 15 Drum 21 Mainspring spring (biasing member)
23 conductor 23a cutting part 51 detection part 54 ferrite magnet (magnet)
72 Reed switch 100 Floating roof tank 102 Floating roof 103 Container body

Claims (3)

A long conductor electrically connecting the container body of the floating roof tank and the floating roof;
A drum that is rotatably supported in a circumferential direction and around which the conductor is wound;
An urging member provided in an inner peripheral portion of the drum and urging the drum in a direction of winding the conductor;
A grounding device for a floating roof type tank, comprising: a detection unit that detects cutting of the conductor. The detector is
A reed switch,
A magnet for closing the contact portion of the reed switch by magnetic force;
With
When the cut conductor is wound up by the biasing member, the cut portion of the conductor jumps up the magnet and opens the contact portion by taking a distance between the reed switch and the magnet. The grounding device for a floating roof type tank according to claim 1.   The grounding device for a floating roof type tank according to claim 2, wherein the magnet is a ferrite magnet.

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