JP5659646B2 - Low temperature tank - Google Patents

Description

  The present invention relates to a structure and a method for installing a lightning conductor.

As is well known, a structure (building) such as an LNG tank includes a lightning protection device. Further, as a lightning-receiving part of this lightning arrester, a stylus or a raised conductor defined in JIS is known. For example, a plurality of projecting needles are provided at a predetermined interval on the roof of the LNG tank, and the raised conductor is provided at a predetermined interval along the roof surface of the LNG tank. Any lightning-receiving portion is connected to a grounding electrode (grounding conductor) buried in the ground through a lightning conductor such as a lowered conductor. When there is a lightning strike on the structure, the current caused by the lightning strikes the tip or the raised conductor → the lightning conductor → the ground electrode → the ground, thereby protecting the structure.
As a prior art related to such a lightning arrester of a structure, Patent Document 1 below discloses a method and an apparatus for installing a lightning arrester provided on a roof of a building.

JP 05-161239 A

  By the way, in a cylindrical large structure such as an LNG tank, a passage (walkway) where an operator walks is provided in an annular shape in the vicinity of the outer periphery of the roof. In an LNG tank provided with such a passage and having a lightning protection facility that uses a raised conductor as a lightning receiving portion, the raised conductor provided on the roof crosses the passage. That is, since the lightning protection equipment is provided in the LNG tank as ancillary equipment after the LNG tank is completed, the raised conductor is provided on the roof after the passage is completed on the roof. Therefore, the raised conductors must be provided across the completed passage on the roof. On the other hand, in an LNG tank including a passage and a lightning protection facility using a stylus as a lightning receiver, a lightning conductor provided on the roof crosses the passage. Such a raised conductor and a lightning conductor are obstacles to walking on the worker's passage, and in some cases, there is a risk of disconnection due to the worker's walking.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to avoid interference of a raised conductor or a lightning conductor with a passage.

  In order to achieve the above object, in the present invention, as a first solving means related to a structure, a structure provided with a lightning arrester and having a passage provided in a roof, wherein A means is adopted in which a portion of the lightning conductor that intersects the passage is buried in a groove formed in the roof.

  As a second solving means relating to a structure, in the first solving means, the buried portion is filled in the groove, a fixture for fixing the plurality of raised conductors or lightning conductors to the roof, and the groove. A means of being made of a filler is adopted.

  As the third solving means relating to the structure, in the first or second solving means, a means is adopted in which the roof is a roof of a low-temperature tank storing liquefied natural gas or liquefied petroleum gas.

  Further, in the present invention, as a first solving means related to the method of installing the lightning conductor, a structure provided with a lightning arrester and having a passage in the roof, which is a structure of a rising conductor or a lightning conductor constituting the lightning arrester. A means is adopted in which a portion intersecting with the passage is accommodated in a groove formed in a roof in advance.

  According to the present invention, since the raised conductor or the lightning conductor is buried in the groove formed in the roof, it is possible to avoid the interference of the raised conductor or the lightning conductor with the passage.

It is a top view which shows the installation state of the lightning protection equipment B in the LNG tank A which concerns on one Embodiment of this invention. It is a principal part enlarged view of the lightning protection equipment B in the LNG tank A which concerns on one Embodiment of this invention, (a) is a top view, (b) is a longitudinal cross-sectional view in the extending direction of the raising conductor 4, (c). FIG. 4 is a longitudinal sectional view in a direction orthogonal to the extending direction of the raised conductor 4.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The LNG tank A according to the present embodiment is a cylindrical structure as is well known, and as shown in FIG. 1, the roof 1, the passage 2, the raised conductor 3, the down conductor (lightning conductor) 4, and the ground conductor 5. (Grounding electrode) and a conductor burying portion 6 are provided. Of these components, the lifting conductor 3, the pulling conductor (lightning conductor) 4 and the grounding conductor 5 (ground electrode) constitute the lightning arrester B.

  The LNG tank A has a double shell structure including an outer tank made of concrete and an inner tank made of a membrane, and is a large structure that stores LNG (liquefied natural gas) in the inner tank. Generally, the LNG tank has a ground type and an underground type, but the LNG tank A is a ground type constructed on the ground, and the height of the roof 1 from the ground reaches several tens of meters. The roof 1 is made of concrete, and is provided in a circular dome shape on the top of a concrete frame erected in a cylindrical shape on the ground. The passage 2 is provided in an annular shape as a walkway where an operator walks around the periphery of the circular dome-shaped roof 1. Such a passage 2 is an incidental facility provided for an operator to pass for the purpose of maintenance of the LNG tank A or the like.

  The raised conductors 3 are conductor plates provided on the roof 1 at a predetermined interval as shown in the figure, and a total of six annular raised conductors 3a for concentrating the circular roof 1 into five blocks, It consists of a plurality of radial winding conductors 3b that connect the annular winding conductors 3a radially at a plurality of locations. As shown in the drawing, the ring-shaped conductor 3a and the radial conductor 3b are connected in a net shape as a whole. These raised conductors 3 are, for example, aluminum plate-like members.

  On the roof 1, as shown in the figure, an LNG pump platform and a safety valve platform are provided, and the annular uplifting conductor 3a and the radial uplifting conductor 3b are provided so as to avoid these platforms. Yes. The LNG pump platform is a structural part in which a LNG pump for discharging LNG (storage) stored in the LNG tank A to the outside is suspended in the LNG tank A and a discharge port is provided for taking out LNG to the outside. The safety valve platform is a structural part provided with a safety valve that functions as a safety device when the internal pressure of the LNG tank A abnormally increases.

  The down conductor 4 connects the annular conductor 3a located on the outermost periphery of the total six conductors 3a and the ground conductor 5, and the surface of the side wall of the LNG tank A as shown in the figure. Are provided in a vertical state at regular intervals. In FIG. 1, a total of six annular conductors 3a are provided and a total of 24 down conductors 4 are provided. These annular conductors 3a, down conductors 4, and radial conductors 3b are also provided. This number is appropriately set according to the size of the LNG tank A. As shown in the figure, the ground conductor 5 is a conductor provided in an annular shape in the ground around the LNG tank A, and is interconnected with the down conductor 4.

  As shown in the figure, the conductive wire burying portion 6 is provided at the intersection of the passage 2 and the radial winding conductor 3b, and is a portion in which the radial winding conductor 3b is embedded in the roof 1. The conductive wire burying portion 6 is the most characteristic component of the LNG tank A, and will be described in detail with reference to the enlarged view of FIG.

  As shown in FIG. 2, the conductor burying portion 6 accommodates the radial conductor 3b in a long groove 1a formed on the roof 1 over a predetermined length, and is provided near both ends of the long groove 1a. The fixed groove 6a fixes the two radial conductors 3b to the roof 1, and the long groove so that the surface of the filler 6b is flush with the surface of the roof 1 by the filler 6b such as mortar. 1a is embedded. Such a conductor burying portion 6 is provided at the intersection with the passage 2 and constitutes a part of the passage 2.

  In addition, in this conducting wire burying part 6, since the filler 6b is softer than concrete, two places of the radial winding conductor 3b are being fixed to the roof 1 with the fixing tool 6a. When the fixture 6a is not provided, there is a risk that the radial uplift conductor 3b may move to some extent in the relatively soft filler 6b when an operator passes through the passage 2, and in some cases the radial uplift conductor 3b may be moved. Since there exists a possibility of fracture | rupture, it is not preferable.

Next, the main function of the LNG tank A configured as described above will be described.
In the lightning arrester B provided in the LNG tank A, when the lifting conductor 3 receives lightning, the current (thunder current) caused by the lightning is increased by the lifting conductor 3 → the pulling conductor 4 (lightning conductor) → the grounding conductor 5. It flows to the ground via. That is, according to such a lightning arrester B, the lightning current can be prevented from flowing inside the LNG tank A, so that the LNG tank A can be protected.

  Further, according to the present LNG tank A, since the conductive wire burying portion 6 is provided for each radial winding conductor 3b that intersects the passage 2, it is possible to avoid the radial winding conductor 3b from interfering with the passage 2. it can. Therefore, according to the LNG tank A, each radial conductor 3b does not become an obstacle to walking on the worker's passage 2, and when the worker walks along the passage 2, the radial conductor 3b. Will not break and the lightning arrester B will not malfunction.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) The lightning arrester B of the above embodiment uses the lifting conductor 3 as the lightning receiving portion, but is not limited to this. The present invention can also be applied to a lightning arrester provided with a stylus as a lightning receiver. That is, in a structure provided with a lightning protection facility including a plurality of projecting needles as lightning receiving parts, the plurality of projecting needles are connected to the grounding conductor by lightning conductors wired on the roof and down conductors provided on the sides of the structure. . Therefore, in a structure equipped with a lightning arrester equipped with a plurality of needles as lightning receivers, lightning conductors wired on the roof interfere with the passage, but interference is avoided by embedding and accommodating the lightning conductors on the roof. can do.

(2) Moreover, although the said embodiment demonstrated the case where this invention was applied to the LNG tank A which is a kind of low temperature tank, the structure in this invention is not limited to an LNG tank. The present invention can be applied to, for example, a low temperature tank such as an LPG tank, and a structure in which a passage is provided on the roof and the passage and the raised conductor or the lightning conductor intersect.

  A ... LNG tank (structure), B ... Lightning protection equipment, 1 ... Roof, 2 ... Passage, 3 ... Raised conductor, 4 ... Down conductor (lightning conductor), 5 ... Ground conductor, 6 ... Conductor buried part

Claims (1)

A low-temperature tank with lightning protection and a passage on the roof,
The portion that intersects with said passage of chest raised conductors or lightning lead constituting the lightning protection equipment is buried in a groove formed in the roof,
The winding conductor is composed of a plurality of annular winding conductors provided concentrically on the roof, and a plurality of radial winding conductors that connect the annular winding conductors at a plurality of locations radially.
With respect to the radial winding conductor that intersects the passage, a fixture for fixing the radial winding conductor to the roof is provided in two places across the passage, and a filler is provided in the groove. A cryogenic tank that is filled .

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