JP2003287198A - Low temperature storage tank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low temperature storage tank capable of securing strength and airtightness of a membrane at a nozzle penetration part of a roof part inner surface without increasing the execution term and execution costs. <P>SOLUTION: A plurality of nozzles penetrating through the roof part are provided to satisfy conditions 1-3 described below at the nozzle penetration part of the membrane in a low temperature storage tank having a parallel contraction type membrane structure on a storage tank inner surface of the roof part. 1, A center of the nozzle penetration part is positioned at a part corresponding to a cross part of a corrugation. 2, The nozzle penetration part is provided not to cross with other corrugation excluding two corrugations composing the cross part mentioned above. 3, The nozzle penetration part is not arranged adjacently via one corrugation in parallel. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-temperature storage tank suitable for storing low-temperature liquefied gas such as LNG and LPG. 2. Description of the Related Art In the case of an underground storage tank for storing low-temperature liquefied gas such as LNG and LPG, a membrane structure provided with a corrugated corrugation for absorbing deformation due to thermal contraction and thermal expansion of the storage tank inner surface. It is often done. In the membrane structure, a cold insulation panel is laid on the entire inner surface of a substantially cylindrical concrete outer tank, and further, a thin plate-shaped membrane component member having liquid tightness and air tightness is provided on the entire inner surface side of the cold insulation panel. It is constructed by welding. In such an underground storage tank, the stored liquid is discharged by a pump barrel that penetrates a roof and reaches the bottom of the storage tank. In recent years, as the size of the storage tank has been increased, a membrane structure has also been used for the inner surface of the roof. However, when the inner surface of the roof has a membrane structure and the diameter of the pump barrel is larger than the interval of corrugations provided in the membrane, the penetrating portion (nozzle penetrating portion) of the pump barrel intersects with the corrugation and corrugates. Will be disrupted. In this case, the deformation due to thermal contraction and thermal expansion of the membrane cannot be sufficiently absorbed by corrugation around the through portion of the pump barrel, and the strength of the membrane may be reduced due to metal fatigue. Therefore, in the prior art, as shown in FIG. 4, a part of the inner surface of the roof has a seal plate structure.
By concentrating the pump barrel on that part,
The aim was to ensure strength against deformation due to thermal expansion and airtightness. [0006] However, in the above-mentioned seal plate structure, the structure for ensuring airtightness is complicated, and as a result, the length of the welding line is very long. Also, reinforcement work for the roof concrete where the seal plate is provided was required. Furthermore, after the seal plate is installed, after the test for confirming the airtightness of the seal plate portion is completed, it is necessary to provide a cool insulator or the like in the seal plate portion to form a cool structure. Therefore, when the seal plate structure is adopted, there is a problem that the construction period is lengthened and the construction cost is increased. The present invention has been made to solve the above problems, and provides a low-temperature storage tank capable of securing the strength and airtightness of a membrane in a nozzle penetration portion on the inner surface of a roof without increasing the construction period and construction cost. The purpose is to do. Means for Solving the Problems The present inventors have studied a nozzle penetrating portion structure which can ensure the strength and airtightness of the membrane at the nozzle penetrating portion on the inner surface of the roof without employing a seal plate structure. Was done. In this study, the positions of the nozzle penetration portions were variously changed in consideration of the relative positional relationship between the plurality of nozzle penetration portions, and a membrane strength test was performed by a strain measurement test. Further, a leak test was performed at the nozzle penetrating portion of the membrane, and an airtightness confirmation test was performed. As a result, it has been found that the strength and airtightness of the membrane can be secured by providing the nozzle penetrating portion at a specific position of the corrugation provided on the membrane on the inner surface of the roof. The present invention has been made based on such findings, and is a low-temperature storage tank having the following features. [1] In a low-temperature storage tank having a parallel-shrinkable membrane structure on the inner surface of the storage tank including the roof, a plurality of nozzles penetrating the roof are formed by the following nozzles 1) to
A low-temperature storage tank provided so as to satisfy the condition of 3). 1) The center of the nozzle penetrating portion is located at a portion corresponding to a cross portion of corrugation. 2) The nozzle penetrating portion is provided so as not to intersect other corrugations other than the two corrugations constituting the cross portion. 3) Do not arrange the nozzle penetrating parts in parallel adjacent to each other via one corrugation. An embodiment of the low-temperature storage tank according to the present invention will be described below. FIGS. 1 to 3 show a plurality of pump barrels 1 penetrating through a roof in an underground storage tank for low-temperature liquefied gas such as LNG and LPG having a parallel-shrinkable membrane structure on the inner surface of the tank including the roof. FIG. 3 is a diagram showing a membrane structure in a penetrating portion (nozzle penetrating portion) of FIG. FIG. 1 is a plan view showing a membrane structure at a nozzle penetrating portion, FIG. 2 is a cross-sectional view at a nozzle penetrating portion, and FIG. 3 is an enlarged view showing a membrane structure around the nozzle penetrating portion. In FIG. 1, reference numeral 2 denotes a manhole provided on the roof, and a penetrating portion (nozzle penetrating portion) formed by the manhole 2 has the same membrane structure as the nozzle penetrating portion formed by the pump barrel 1. be able to. Therefore, in the following description, the structure of the nozzle penetrating portion by the pump barrel 1 is equivalent to the manhole 2 provided on the roof portion.
Can be read as the membrane structure in the through portion (nozzle through portion). As shown in FIGS. 1 to 3, in the present invention, a plurality of pump barrels 1 penetrating a roof portion are provided at a nozzle penetrating portion A of a membrane so as to satisfy the following conditions 1) to 3). Things. 1) The center of the nozzle penetrating portion A is located at a portion corresponding to the cross portion X of corrugation. 2) The nozzle penetrating portion A is provided so as not to intersect with the other corrugations 5c, 5d, 5e, 5f except for the two corrugations 5a, 5b constituting the cross portion X. 3) The nozzle penetrating portions A are not arranged side by side in a state adjacent to each other via one corrugation. Here, the pump barrel 1 penetrating the roof portion
The center of the nozzle penetrating section A is the cross section X of the corrugation.
, The absorption of the deformation due to the corrugation cut off by the nozzle penetrating portion A allows the corrugations 5c and 5 around the nozzle penetrating portion A to be absorbed.
d, 5e, 5f. Further, the nozzle penetration portion A of the pump barrel 1 penetrating the roof portion has another corrugation 5 except for the two corrugations 5a and 5b constituting the cross portion X.
By providing so as not to intersect with c, 5d, 5e, 5f, only the absorbed amount of deformation due to corrugation cut off by the nozzle penetrating portion X needs to be absorbed by the surrounding corrugations 5c, 5d, 5e, 5f. Can be minimized. Further, in order to suppress an increase in the burden due to corrugation around the nozzle penetrating portion A, the nozzle penetrating portions A of the plurality of pump barrels 1 penetrating the roof are arranged in parallel in a state adjacent to each other via one corrugation. It is necessary not to arrange. This is because, if the nozzle penetrating portions A are arranged in parallel, a load of twice the amount of deformation absorption is applied to the intermediate corrugation, which may cause a problem in strength. That is, in FIG.
a, b, c adjacent to the area surrounded by c, 5d, 5e, 5f via corrugations 5c, 5d, 5e, 5f;
Other nozzle penetrations cannot be arranged in the area (d), but other nozzle penetrations can be arranged in the area (e). Thus, even when a plurality of pump barrels are made to penetrate the roof, it is possible to ensure sufficient strength of the membrane at the nozzle penetrating portion without employing a seal plate structure for the roof. Referring to FIG. 3, an example of the membrane airtight structure of the pump barrel penetration will be described. A sleeve 3 is usually provided around the portion of the pump barrel 1 that penetrates the roof, in order to reduce the influence of the heat shrinkage / expansion of the pump barrel on the roof. Therefore, FIG. 3 shows a case with a sleeve, but it goes without saying that the same can be applied to a case without a sleeve. Here, the sleeve 3 is welded to the pump barrel 1 while ensuring airtightness. The airtight structure of the membrane nozzle penetrating portion on the inner surface of the roof is such that a donut-shaped fitting plate 4 is welded and joined around a sleeve 3 provided around the pump barrel 1, and further, the fitting plate 4 and the nozzle penetrating portion are joined together. The hermeticity is ensured by welding to the peripheral membrane 7. Furthermore, the ends of the corrugations 5a and 5b cut off by providing the nozzle penetration portions are welded to the ends of the corrugations 5a and 5b and the fitting plate 4 using the sealing cap 6 to ensure airtightness. Thus, the airtightness of the membrane nozzle penetrating portion on the inner surface of the roof can be ensured without employing a seal plate structure. Since a special structure such as a seal plate according to the related art is not used around the nozzle penetrating portion, the test for airtightness can be performed by the same method as the test for airtightness of a normal membrane structure. Therefore, there is no need for a special airtightness confirmation test to be performed on the seal plate structure, and workability is improved. With the above configuration, it is possible to secure sufficient strength and airtightness in the membrane nozzle penetrating portion on the inner surface of the roof without employing a seal plate structure. The low-temperature storage tank according to the present invention is not limited to the above-described underground storage tank, but is similarly applicable to, for example, an above-ground storage tank. As described above, according to the present invention, a low-temperature storage tank capable of ensuring the strength and airtightness of the membrane at the nozzle penetration portion on the inner surface of the roof without increasing the construction period and construction cost. Provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a membrane structure in a nozzle penetrating portion in one embodiment of the present invention. FIG. 2 is a cross-sectional view of a nozzle penetrating portion in one embodiment of the present invention. FIG. 3 is an enlarged view showing a membrane structure around a nozzle penetrating portion in one embodiment of the present invention. FIG. 4 is a view showing a seal plate structure of a nozzle penetrating portion according to the related art. [Description of Signs] 1 Pump barrel 2 Manhole 3 Sleeve 4 Connecting plate 5 Corrugation 6 Sealing cap 7 Membrane

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Hisaya Koga             1-2-1 Marunouchi, Chiyoda-ku, Tokyo Sun             Honko Co., Ltd. (72) Inventor Keiji Yarimizu             1-2-1 Marunouchi, Chiyoda-ku, Tokyo Sun             Honko Co., Ltd. (72) Inventor Makoto Suga             Tokyo Gas, 1-5-20 Minato-ku, Tokyo             Inside the company (72) Inventor Shingo Arai             Tokyo Gas, 1-5-20 Minato-ku, Tokyo             Inside the company (72) Inventor Tomoaki Matsumura             Tokyo Gas, 1-5-20 Minato-ku, Tokyo             Inside the company F-term (reference) 3E070 AA03 AB32 DA02 GB04 GB06                       LA07 MA01 NA01 QA04                 3E073 AA01 BA01 BA38 BB02 CA01

Claims (1)

Claims: 1. A low-temperature storage tank having a parallel-shrinkable membrane structure on the inner surface of a storage tank including a roof part, wherein a plurality of nozzles penetrating the roof part are formed by the following nozzle-penetrating parts of the membrane: A low-temperature storage tank provided so as to satisfy the condition of 3). 1) The center of the nozzle penetrating portion is located at a portion corresponding to a cross portion of corrugation. 2) The nozzle penetrating portion is provided so as not to intersect other corrugations other than the two corrugations constituting the cross portion. 3) Do not arrange the nozzle penetrating parts in parallel adjacent to each other via one corrugation.