JP7358072B2 - Thermal insulation material for liquefied natural gas tanks, its construction method, and liquefied natural gas tanks - Google Patents

Thermal insulation material for liquefied natural gas tanks, its construction method, and liquefied natural gas tanks Download PDF

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JP7358072B2
JP7358072B2 JP2019092827A JP2019092827A JP7358072B2 JP 7358072 B2 JP7358072 B2 JP 7358072B2 JP 2019092827 A JP2019092827 A JP 2019092827A JP 2019092827 A JP2019092827 A JP 2019092827A JP 7358072 B2 JP7358072 B2 JP 7358072B2
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insulating material
heat insulating
natural gas
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steel plate
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正明 加藤
久美 後藤
直樹 鎌田
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Ask Sanshin Engineering Corp
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本発明は、液化天然ガスタンク用断熱材およびその施工方法並びに液化天然ガスタンクに関し、詳しくは、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも亀裂や剥離等が抑制され、施工も容易な液化天然ガスタンク用断熱材およびその施工方法並びに該断熱材を備えてなる液化天然ガスタンクに関する。 The present invention relates to a heat insulating material for a liquefied natural gas tank, a method of installing the same, and a liquefied natural gas tank, and more particularly, the present invention relates to a heat insulating material for a liquefied natural gas tank, a method for installing the same, and a liquefied natural gas tank. The present invention relates to a heat insulating material for a liquefied natural gas tank, a method for constructing the same, and a liquefied natural gas tank equipped with the heat insulating material.

液化天然ガス（以下、ＬＮＧと呼ぶことがある）を運搬または燃料とするＬＮＧ運搬船は、－１６３℃ともなる極低温のＬＮＧを貯蔵するＬＮＧタンクを備えている。ＬＮＧタンクにおいては、国際海事機関（ＩＭＯ）によって基準が定められ、その内、自立タンク方式としては完全二次防壁のタイプＡ、部分二次防壁のタイプＢ、二次防壁不要の圧力容器であるタイプＣの各ＬＮＧタンクがある。 LNG carriers that transport or use liquefied natural gas (hereinafter sometimes referred to as LNG) as fuel are equipped with LNG tanks that store LNG at an extremely low temperature of -163°C. Standards for LNG tanks have been established by the International Maritime Organization (IMO), and among these, self-supporting tank systems include type A with a complete secondary barrier, type B with a partial secondary barrier, and pressure vessels that do not require a secondary barrier. There are each type C LNG tank.

前記タイプＣのＬＮＧタンクは一般的に、非大型船舶に搭載され、ＬＮＧの内部圧力に十分耐え得る鋼製となっている。またＬＮＧは上記のように極低温であるがために、タイプＣのＬＮＧタンクの外表面には例えば樹脂発泡体からなる多数の断熱材ボードが設けられている。 The Type C LNG tank is generally mounted on a non-large ship and is made of steel that can sufficiently withstand the internal pressure of LNG. Further, since LNG is at an extremely low temperature as described above, a large number of heat insulating boards made of resin foam, for example, are provided on the outer surface of a type C LNG tank.

しかしながら、従来の前記断熱材ボードは、亀裂や剥離が生じ易いという問題点がある。その理由として、鋼製のＬＮＧタンクが内部に存在する極低温のＬＮＧによって顕著に収縮し、断熱材ボードが収縮した鋼に追随できないことが挙げられる。
一方、ＬＮＧタンクの外表面に多数の断熱材パネルを設けると、ＬＮＧタンクと断熱材パネルとの間の固定部や断熱材パネルの目地部により断熱効果が低下してしまうという問題点もある。 However, the conventional heat insulating board has a problem in that it is prone to cracking and peeling. The reason for this is that the steel LNG tank contracts significantly due to the extremely low temperature LNG inside, and the insulation board cannot follow the shrinkage of the steel.
On the other hand, when a large number of heat insulating panels are provided on the outer surface of the LNG tank, there is a problem that the heat insulating effect is reduced due to the fixing portion between the LNG tank and the heat insulating panel and the joints between the heat insulating panels.

かかる問題点を解消するために、例えば特許文献１（特開平６－７４３９４号公報）には、タンク鋼鈑の外表面にグラスウールを貼着し、該グラスウール上にグラスクロスを貼着固定し、該グラスクロス上に樹脂発泡材を吹き付け、該吹き付けた樹脂発泡材上に耐食性金属からなる金網を取り付け、該金網上から再度樹脂発泡材を吹き付けてなることを特徴とする低温貯蔵用金属製タンクの保冷構造が開示されている。
しかし、特許文献１に開示された技術でも、鋼板の収縮による樹脂発泡材の亀裂や剥離の問題点が依然として残り、またその施工にも高いコストがかかるという問題点がある。 In order to solve this problem, for example, Patent Document 1 (Japanese Unexamined Patent Publication No. 6-74394) discloses that glass wool is attached to the outer surface of a tank steel plate, and a glass cloth is attached and fixed on the glass wool. A metal tank for low-temperature storage, characterized in that a resin foam material is sprayed onto the glass cloth, a wire mesh made of a corrosion-resistant metal is attached to the sprayed resin foam material, and the resin foam material is again sprayed onto the wire mesh. A cold storage structure is disclosed.
However, even with the technique disclosed in Patent Document 1, there still remains the problem of cracking and peeling of the resin foam material due to shrinkage of the steel plate, and there is also the problem that the construction thereof is expensive.

特開平６－７４３９４号公報Japanese Patent Application Publication No. 6-74394

したがって本発明の目的は、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも亀裂や剥離等が抑制され、施工も容易な液化天然ガスタンク用断熱材およびその施工方法を提供することにある。
また本発明の別の目的は、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも亀裂や剥離等が抑制された前記断熱材を備えてなる液化天然ガスタンクを提供することにある。 Therefore, an object of the present invention is to provide a heat insulating material for a liquefied natural gas tank that suppresses cracking, peeling, etc. even when a steel plate of a liquefied natural gas tank undergoes significant thermal contraction, and is easy to install, and a method for installing the same. .
Another object of the present invention is to provide a liquefied natural gas tank equipped with the above-mentioned heat insulating material that suppresses cracking, peeling, etc. even when significant thermal contraction occurs in the steel plate of the liquefied natural gas tank.

本発明者らは鋭意研究を重ねた結果、断熱材としてタンク鋼板側から外側に向かって密度が減少する樹脂発泡体を用いることにより、前記課題を解決できることを見い出し、本発明を完成するに至った。
すなわち本発明は以下の通りである。 As a result of extensive research, the present inventors have discovered that the above problem can be solved by using a resin foam whose density decreases from the tank steel plate side outward as a heat insulating material, and have completed the present invention. Ta.
That is, the present invention is as follows.

１．液化天然ガスタンクのタンク鋼板の外表面に設けられる断熱材であって、
前記断熱材は、樹脂発泡体を含み、
前記断熱材は、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が減少する密度勾配を有する
ことを特徴とする液化天然ガスタンク用断熱材。
２．前記樹脂発泡体が、ポリウレタンフォームであることを特徴とする前記１に記載の液化天然ガスタンク用断熱材。
３．前記断熱材は、前記タンク鋼板側から外側に向かって、８０ｋｇ／ｍ３～３０ｋｇ／ｍ３の範囲で前記樹脂発泡体の密度が減少する密度勾配を有することを特徴とする前記１または２に記載の液化天然ガスタンク用断熱材。
４．前記断熱材の厚さが、３００ｍｍ～５００ｍｍの範囲内であることを特徴とする前記１～３のいずれかに記載の液化天然ガスタンク用断熱材。
５．前記断熱材は、厚さ方向において密度が異なる樹脂発泡体の複数の層からなることにより、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が段階的に減少する密度勾配を有することを特徴とする前記１～４のいずれかに記載の液化天然ガスタンク用断熱材。
６．前記断熱材の厚さ方向と直交する方向に平面を有するように、ガラスメッシュが設けられてなることを特徴とする前記１～５のいずれかに記載の液化天然ガスタンク用断熱材。
７．液化天然ガスタンクのタンク鋼板の外表面に、樹脂発泡体を含む断熱材を設ける断熱材形成工程を有し、
前記断熱材形成工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が減少する密度勾配を有する
ことを特徴とする液化天然ガスタンク用断熱材の施工方法。
８．前記樹脂発泡体が、ポリウレタンフォームであり、
前記断熱材形成工程は、前記ポリウレタンフォームを吹き付ける吹付工程を含み、
前記吹付工程は、密度の異なるポリウレタンフォームを複数回にわたり吹き付けて前記タンク鋼板の外表面に断熱材を形成するものであり、
前記吹付工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記ポリウレタンフォームの密度が減少する密度勾配が形成される
ことを特徴とする前記７に記載の液化天然ガスタンク用断熱材の施工方法。
９．前記１～５のいずれかに記載の液化天然ガスタンク用断熱材が、タンク鋼板の外表面に設けられ、前記断熱材は、前記タンク鋼板側から外側に向かって前記ポリウレタンフォームの密度が減少する密度勾配を有する
ことを特徴とする液化天然ガスタンク。
１０．船舶に固定される前記９に記載の液化天然ガスタンク。
１１．タイプＣである前記１０に記載の液化天然ガスタンク。 1. A heat insulating material provided on the outer surface of a tank steel plate of a liquefied natural gas tank,
The heat insulating material includes a resin foam,
A heat insulating material for a liquefied natural gas tank, wherein the heat insulating material has a density gradient in which the density of the resin foam decreases from the tank steel plate side toward the outside.
2. 2. The heat insulating material for a liquefied natural gas tank as described in 1 above, wherein the resin foam is a polyurethane foam.
3. 1 or 2 above, wherein the heat insulating material has a density gradient such that the density of the resin foam decreases in a range of 80 kg/m 3 to 30 kg/m 3 from the tank steel plate side to the outside. Insulation material for liquefied natural gas tanks as described.
4. 4. The insulation material for a liquefied natural gas tank according to any one of items 1 to 3 above, wherein the thickness of the insulation material is within a range of 300 mm to 500 mm.
5. The heat insulating material is composed of a plurality of layers of resin foam having different densities in the thickness direction, so that the heat insulating material has a density gradient in which the density of the resin foam gradually decreases from the tank steel plate side toward the outside. 5. The insulating material for a liquefied natural gas tank according to any one of 1 to 4 above, characterized by:
6. 6. The heat insulating material for a liquefied natural gas tank according to any one of items 1 to 5 above, characterized in that a glass mesh is provided so as to have a plane in a direction perpendicular to the thickness direction of the heat insulating material.
7. A heat insulating material forming step of providing a heat insulating material containing a resin foam on the outer surface of a tank steel plate of a liquefied natural gas tank,
A method for constructing a heat insulating material for a liquefied natural gas tank, wherein the heat insulating material has a density gradient in which the density of the resin foam decreases from the tank steel plate side toward the outside in the heat insulating material forming step.
8. The resin foam is polyurethane foam,
The heat insulating material forming step includes a spraying step of spraying the polyurethane foam,
The spraying step involves spraying polyurethane foam with different densities multiple times to form a heat insulating material on the outer surface of the tank steel plate,
7. The heat insulating material for a liquefied natural gas tank as described in 7 above, wherein the spraying step forms a density gradient in the heat insulating material in which the density of the polyurethane foam decreases from the tank steel plate side toward the outside. Construction method.
9. The liquefied natural gas tank heat insulating material according to any one of 1 to 5 above is provided on the outer surface of a tank steel plate, and the heat insulating material has a density such that the density of the polyurethane foam decreases from the tank steel plate side toward the outside. A liquefied natural gas tank characterized by having a slope.
10. 10. The liquefied natural gas tank according to 9 above, which is fixed to a ship.
11. 11. The liquefied natural gas tank according to 10 above, which is Type C.

本発明の液化天然ガスタンク用断熱材は、液化天然ガスタンクのタンク鋼板の外表面に設けられ、樹脂発泡体を含むとともに、前記タンク鋼板側から外側に向かって樹脂発泡体の密度が減少する密度勾配を有することを特徴としているので、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも、高密度の樹脂発泡体が前記鋼板の熱収縮に追随し、断熱材の亀裂や剥離等を抑制できる。また高密度の樹脂発泡体は断熱性を低下させるが、低密度の樹脂発泡体は断熱性に優れるので、高密度の樹脂発泡体の有する前記欠点を補うことができる。また、樹脂発泡体の密度は、発泡剤の量により容易に制御できるため、施工性にも優れる。
また本発明の液化天然ガスタンク用断熱材の施工方法は、液化天然ガスタンクのタンク鋼板の外表面に、樹脂発泡体を含む断熱材を設ける断熱材形成工程を有し、前記断熱材形成工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が減少する密度勾配を有することを特徴としているので、施工が容易であるとともに、コスト面にも優れる。また、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも、断熱材の亀裂や剥離等を抑制できる。
また本発明の液化天然ガスタンクは、前記本発明の断熱材を備えていることを特徴としているので、液化天然ガスタンクの鋼板に顕著な熱収縮が生じた場合でも亀裂や剥離等が抑制される。また、断熱性および施工性にも優れる。 The heat insulating material for a liquefied natural gas tank of the present invention is provided on the outer surface of a tank steel plate of a liquefied natural gas tank, contains a resin foam, and has a density gradient in which the density of the resin foam decreases from the tank steel plate side to the outside. Even if the steel plate of the liquefied natural gas tank undergoes significant thermal contraction, the high-density resin foam will follow the thermal contraction of the steel plate, suppressing cracks and peeling of the insulation material. can. Further, although high-density resin foam reduces heat insulating properties, low-density resin foam has excellent heat insulating properties, so it can compensate for the above-mentioned drawbacks of high-density resin foam. Furthermore, since the density of the resin foam can be easily controlled by adjusting the amount of blowing agent, it has excellent workability.
Further, the method for constructing a heat insulating material for a liquefied natural gas tank of the present invention includes a heat insulating material forming step of providing a heat insulating material containing a resin foam on the outer surface of a tank steel plate of a liquefied natural gas tank, and the step of forming a heat insulating material includes: The heat insulating material is characterized by having a density gradient in which the density of the resin foam decreases from the tank steel plate side toward the outside, so it is easy to construct and is also excellent in terms of cost. Further, even if significant thermal contraction occurs in the steel plate of the liquefied natural gas tank, cracking or peeling of the heat insulating material can be suppressed.
Furthermore, since the liquefied natural gas tank of the present invention is characterized by comprising the heat insulating material of the present invention, cracking, peeling, etc. are suppressed even if significant thermal contraction occurs in the steel plate of the liquefied natural gas tank. It also has excellent heat insulation properties and workability.

本発明に適用され得るタイプＣの液化天然ガスタンクを説明するための図である。FIG. 2 is a diagram for explaining a type C liquefied natural gas tank that can be applied to the present invention. 本発明の液化天然ガスタンク用断熱材を説明するための断面図である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view for explaining a heat insulating material for a liquefied natural gas tank according to the present invention. 本発明の液化天然ガスタンク用断熱材の別の形態を説明するための断面図である。It is a sectional view for explaining another form of the heat insulating material for liquefied natural gas tanks of the present invention. 本発明の液化天然ガスタンク用断熱材の別の形態を説明するための断面図である。It is a sectional view for explaining another form of the heat insulating material for liquefied natural gas tanks of the present invention.

以下、本発明の実施形態を図面を参照しながらさらに説明する。
図１は、本発明に適用され得るタイプＣの液化天然ガスタンクを説明するための図であり、図１（ａ）は液化天然ガスタンクの長手方向の側面図であり、（ｂ）は液化天然ガスタンクの直径方向の正面図である。 Embodiments of the present invention will be further described below with reference to the drawings.
FIG. 1 is a diagram for explaining a type C liquefied natural gas tank that can be applied to the present invention, FIG. 1(a) is a longitudinal side view of the liquefied natural gas tank, and FIG. FIG.

図１において、タイプＣの液化天然ガスタンク（ＬＮＧタンク）１は、円筒状の圧力容器１２を備え、圧力容器１２は架台１４によって支持されている。一般的にタイプＣのＬＮＧタンクは、３０～１０，０００ｍ３の容量を有し、タンクの数量としては１個または複数個である。圧力容器１２は、アルミニウム、ステンレス鋼、ニッケル鋼等の鋼板から構成される。 In FIG. 1 , a type C liquefied natural gas tank (LNG tank) 1 includes a cylindrical pressure vessel 12 , and the pressure vessel 12 is supported by a frame 14 . Generally, Type C LNG tanks have a capacity of 30 to 10,000 m 3 , and the number of tanks is one or more. The pressure vessel 12 is made of a steel plate such as aluminum, stainless steel, or nickel steel.

圧力容器１２における鋼板の熱膨張収縮特性の一例として、ステンレス鋼からなる圧力容器に、－１６３℃ともなる極低温のＬＮＧを貯蔵すると、ステンレス鋼が１ｍあたり約３ｍｍ熱収縮する。 As an example of the thermal expansion and contraction characteristics of a steel plate in the pressure vessel 12, when LNG at an extremely low temperature of -163° C. is stored in a pressure vessel made of stainless steel, the stainless steel thermally contracts by about 3 mm per meter.

本発明の断熱材は、圧力容器１２の外表面に設けられる。
図２は、本発明の断熱材を説明するための断面図である。
図２において、本発明の断熱材２０は、圧力容器の鋼板１２１上に、鋼板１２１側から外側（Ａ方向）に向かって樹脂発泡体２２、２４が設けられ、樹脂発泡体２４の密度は、樹脂発泡体２２の密度よりも低く設定されている。すなわち、本発明の断熱材２０は、圧力容器の鋼板１２１側から外側（Ａ方向）に向かって樹脂発泡体の密度が減少する密度勾配を有する。また、樹脂発泡体２４の上部、すなわち断熱材の最表面側には、さらに亀裂や剥離を抑制する目的でＦＲＰ（繊維強化プラスチック）やポリウレア樹脂からなる補強層２６を設けることもできる。 The heat insulating material of the present invention is provided on the outer surface of the pressure vessel 12.
FIG. 2 is a sectional view for explaining the heat insulating material of the present invention.
In FIG. 2, in the heat insulating material 20 of the present invention, resin foams 22 and 24 are provided on a steel plate 121 of a pressure vessel from the steel plate 121 side toward the outside (direction A), and the density of the resin foam 24 is as follows. The density is set lower than the density of the resin foam 22. That is, the heat insulating material 20 of the present invention has a density gradient in which the density of the resin foam decreases from the steel plate 121 side of the pressure vessel toward the outside (direction A). Further, a reinforcing layer 26 made of FRP (fiber reinforced plastic) or polyurea resin may be provided on the upper part of the resin foam 24, that is, on the outermost surface side of the heat insulating material, for the purpose of further suppressing cracking and peeling.

本発明では、断熱材２０が鋼板１２１側から外側に向かって、８０ｋｇ／ｍ３～３０ｋｇ／ｍ３の範囲で樹脂発泡体の密度が減少する密度勾配を有することが好ましい。このように密度を設定することで、断熱材の亀裂や剥離等をさらに抑制することができる。 In the present invention, it is preferable that the heat insulating material 20 has a density gradient in which the density of the resin foam decreases from the steel plate 121 side toward the outside in a range of 80 kg/m 3 to 30 kg/m 3 . By setting the density in this way, it is possible to further suppress cracking, peeling, etc. of the heat insulating material.

なお本発明で言う密度は、ＪＩＳ Ｋ ７２２２ 「発泡プラスチック及びゴム－見掛け密度の求め方」により一般的に測定される。 Note that the density referred to in the present invention is generally measured according to JIS K 7222 "Foamed plastics and rubber - How to determine apparent density."

例えば図２に示す形態において、樹脂発泡体２２の密度は、例えば、３５ｋｇ／ｍ３～８０ｋｇ／ｍ３であり、好ましくは５０ｋｇ／ｍ３～６５ｇ／ｍ３である。また、樹脂発泡体２４の密度は、例えば３０ｋｇ／ｍ３～５５ｋｇ／ｍ３であり、好ましくは３５ｋｇ／ｍ３～５０ｋｇ／ｍ３である。なお、樹脂発泡体２２と２４との密度差は、例えば５ｋｇ／ｍ３～２５ｋｇ／ｍ３であり、好ましくは１０ｋｇ／ｍ３～２０ｋｇ／ｍ３である。 For example, in the form shown in FIG. 2, the density of the resin foam 22 is, for example, 35 kg/m 3 to 80 kg/m 3 , preferably 50 kg/m 3 to 65 g/m 3 . Further, the density of the resin foam 24 is, for example, 30 kg/m 3 to 55 kg/m 3 , preferably 35 kg/m 3 to 50 kg/m 3 . The density difference between the resin foams 22 and 24 is, for example, 5 kg/m 3 to 25 kg/m 3 , preferably 10 kg/m 3 to 20 kg/m 3 .

本発明の断熱材２０の合計の厚さは、３００ｍｍ～５００ｍｍであることが好ましく、３５０ｍｍ～４５０ｍｍであることがさらに好ましい。 The total thickness of the heat insulating material 20 of the present invention is preferably 300 mm to 500 mm, more preferably 350 mm to 450 mm.

図２に示す形態において、樹脂発泡体２２の厚さとしては、例えば２０ｍｍ～１００ｍｍであり、４０ｍｍ～８０ｍｍが好ましい。樹脂発泡体２４の厚さとしては、例えば２００ｍｍ～４８０ｍｍであり、２５０ｍｍ～４５０ｍｍが好ましい。 In the embodiment shown in FIG. 2, the thickness of the resin foam 22 is, for example, 20 mm to 100 mm, preferably 40 mm to 80 mm. The thickness of the resin foam 24 is, for example, 200 mm to 480 mm, preferably 250 mm to 450 mm.

なお本発明の断熱材は、図２に示す形態に制限されない。例えば図３に示すように、樹脂発泡体２２と樹脂発泡体２４との間にｎ個の断熱材の層を介在させ、鋼板１２１側から外側に向かって樹脂発泡体の密度が段階的に減少する密度勾配を持たせてもよい。この形態では、様々な形状の圧力容器に対応が可能であり、断熱材の亀裂や剥離を抑制できる。なお、ｎは０～４が好ましい。 Note that the heat insulating material of the present invention is not limited to the form shown in FIG. For example, as shown in FIG. 3, n layers of heat insulating material are interposed between the resin foam 22 and the resin foam 24, and the density of the resin foam is gradually decreased from the steel plate 121 side to the outside. It is also possible to have a density gradient. This form can be applied to pressure vessels of various shapes, and can suppress cracking and peeling of the heat insulating material. Note that n is preferably 0 to 4.

このように本発明の断熱材は、厚さ方向において密度が異なる樹脂発泡体の複数の層からなることにより、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が段階的に減少する密度勾配を有することが好ましい。このような形態によれば、施工が容易であるとともに、断熱材の亀裂や剥離を良好に抑制できる。 In this way, the heat insulating material of the present invention is composed of a plurality of layers of resin foam having different densities in the thickness direction, so that the density of the resin foam gradually decreases from the tank steel plate side to the outside. It is preferable to have a density gradient. According to such a form, construction is easy and cracking and peeling of the heat insulating material can be suppressed well.

また本発明の別の形態によれば、断熱材の厚さ方向と直交する方向に平面を有するように、ガラスメッシュを設けてもよい。このような形態によれば、断熱材の亀裂や剥離がさらに抑制される。図４は、ガラスメッシュを設けた本発明の断熱材を説明するための断面図である。樹脂発泡体２２と樹脂発泡体２４との間に、ガラスメッシュ４２が設けられている。ガラスメッシュ４２の目幅は、例えば５ｍｍ～１５ｍｍであり、好ましくは７．５ｍｍ～１２．５ｍｍである。なお、このようなガラスメッシュ４２は、図３で示したように樹脂発泡体２２と樹脂発泡体２４との間にｎ個の断熱材の層を介在させた場合は、密度の異なる層を積層する毎にガラスメッシュ４２を設置してもよい。 According to another aspect of the present invention, a glass mesh may be provided so as to have a plane in a direction perpendicular to the thickness direction of the heat insulating material. According to such a configuration, cracking and peeling of the heat insulating material are further suppressed. FIG. 4 is a sectional view for explaining the heat insulating material of the present invention provided with a glass mesh. A glass mesh 42 is provided between the resin foam 22 and the resin foam 24. The mesh width of the glass mesh 42 is, for example, 5 mm to 15 mm, preferably 7.5 mm to 12.5 mm. Note that when n layers of heat insulating material are interposed between the resin foam 22 and the resin foam 24 as shown in FIG. The glass mesh 42 may be installed every time.

なお、樹脂発泡体２２、２４は、鋼板１２１の熱収縮に対する追随性が良好であるという観点から、かつ施工性に優れるという観点から、２液型のポリウレタンフォームであることが好ましい。 Note that the resin foams 22 and 24 are preferably two-component polyurethane foams from the viewpoint of good ability to follow the thermal contraction of the steel plate 121 and from the viewpoint of excellent workability.

ポリウレタンフォームの密度は、発泡剤（例えばハイドロフルオロカーボンＨＦＣや水等）の注入量により制御することが可能である。 The density of the polyurethane foam can be controlled by the amount of blowing agent (eg, hydrofluorocarbon HFC, water, etc.) injected.

樹脂発泡体２２の引張強さは、亀裂や剥離をさらに抑制するという観点から、例えば常温（２０℃）において２０～５５Ｎ／ｃｍ２であることが好ましく、樹脂発泡体２４の前記引張強さは、１０～３５Ｎ／ｃｍ２であることが好ましい。
引張強さは、ＪＩＳ Ａ ９５１１「発泡プラスチック保温材」により一般的に測定される。 The tensile strength of the resin foam 22 is preferably 20 to 55 N/cm 2 at room temperature (20° C.), for example, from the viewpoint of further suppressing cracking and peeling, and the tensile strength of the resin foam 24 is , 10 to 35 N/cm 2 is preferable.
Tensile strength is generally measured according to JIS A 9511 "Foamed plastic insulation materials."

本発明の液化天然ガスタンク用断熱材の施工方法は、液化天然ガスタンクのタンク鋼板の外表面に、樹脂発泡体を含む断熱材を設ける断熱材形成工程を有し、前記断熱材形成工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が減少する密度勾配を有することを特徴とする。
とくに好適な前記施工方法は、前記樹脂発泡体が、ポリウレタンフォームであり、前記断熱材形成工程は、前記ポリウレタンフォームを吹き付ける吹付工程を含み、前記吹付工程は、密度の異なるポリウレタンフォームを複数回にわたり吹き付けて前記タンク鋼板の外表面に断熱材を形成するものであり、前記吹付工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記ポリウレタンフォームの密度が減少する密度勾配が形成されるというものである。
ポリウレタンフォームの吹き付けは公知技術を適用することができる。例えばポリウレタンフォームを２液型とし、圧力および温度を制御しながら２液を撹拌し、スプレーにより吹き付ける方法が挙げられる。 The method for constructing a heat insulating material for a liquefied natural gas tank according to the present invention includes a step of forming a heat insulating material containing a resin foam on the outer surface of a tank steel plate of a liquefied natural gas tank, and in the step of forming the heat insulating material, the The heat insulating material is characterized in that it has a density gradient in which the density of the resin foam decreases from the tank steel plate side toward the outside.
In the particularly preferred construction method, the resin foam is polyurethane foam, and the heat insulating material forming step includes a spraying step of spraying the polyurethane foam, and the spraying step includes spraying polyurethane foam with different densities multiple times. A heat insulating material is formed on the outer surface of the tank steel plate by spraying, and the spraying process forms a density gradient in the heat insulating material in which the density of the polyurethane foam decreases from the tank steel plate side toward the outside. This means that
For spraying the polyurethane foam, known techniques can be applied. For example, there is a method in which polyurethane foam is made into a two-component type, the two components are stirred while controlling the pressure and temperature, and then the foam is sprayed.

また、例えば樹脂発泡体２２、２４の形成は、それぞれの発泡体が所定の厚さとなるまで、複数回吹き付けてもよい。例えば樹脂発泡体２２の厚さが厚い場合（例えば１００ｍｍ程度）、１回の吹き付け厚を４０ｍｍ以下とし、この吹き付けを複数回繰り返すことにより、所定の厚さ（１００ｍｍ）に樹脂発泡体２２を形成することができる。その他の発泡体の層についても同様である。 Further, for example, the resin foams 22 and 24 may be formed by spraying multiple times until each foam reaches a predetermined thickness. For example, when the thickness of the resin foam 22 is thick (for example, about 100 mm), the thickness of one spraying is 40 mm or less, and this spraying is repeated multiple times to form the resin foam 22 to a predetermined thickness (100 mm). can do. The same applies to other foam layers.

本発明の液化天然ガスタンクは、本発明の断熱材を備えていることを特徴とする。すなわち、本発明の断熱材をタンク鋼板の外表面に設け、断熱材が前記タンク鋼板側から外側に向かってポリウレタンフォームの密度が減少する密度勾配を有することを特徴とする。本発明のＬＮＧタンクは、船舶に固定された、とくにタイプＣのＬＮＧタンクとするのが好適である。上述のように、タイプＣのＬＮＧタンクは、船舶の大きさ等によって様々な形状を取り得るが、本発明の断熱材を適用することにより、ＬＮＧタンクの鋼板に顕著な熱収縮が生じた場合でも亀裂や剥離等が抑制される。 The liquefied natural gas tank of the present invention is characterized by being equipped with the heat insulating material of the present invention. That is, the heat insulating material of the present invention is provided on the outer surface of a tank steel plate, and the heat insulating material has a density gradient in which the density of the polyurethane foam decreases from the tank steel plate side toward the outside. The LNG tank of the present invention is preferably a type C LNG tank fixed to a ship. As mentioned above, Type C LNG tanks can take various shapes depending on the size of the ship, etc., but if significant heat shrinkage occurs in the steel plate of the LNG tank by applying the insulation material of the present invention, However, cracking and peeling are suppressed.

なお、本発明者らは、タイプＣのＬＮＧタンクにＬＮＧを貯蔵し、圧力容器の鋼板側から外側に向かって樹脂発泡体の密度が減少する密度勾配を有する断熱材を用いることにより、鋼板が熱収縮しても断熱材に亀裂や剥離が生じないことを確認している。
具体的には、図２に示す形態において、樹脂発泡体２２および２４として２液型のポリウレタンフォームを用い、樹脂発泡体２２の密度を６０ｋｇ／ｍ３、樹脂発泡体２４の密度を４０ｋｇ／ｍ３とし、断熱材の合計厚さを４００ｍｍとしたときに、鋼板が熱収縮しても断熱材に亀裂や剥離が生じないことを確認している。 The present inventors stored LNG in a type C LNG tank and used a heat insulating material with a density gradient in which the density of the resin foam decreases from the steel plate side to the outside of the pressure vessel. We have confirmed that the insulation material does not crack or peel even when it shrinks due to heat.
Specifically, in the form shown in FIG. 2, two-component polyurethane foam is used as the resin foams 22 and 24, and the density of the resin foam 22 is 60 kg/m 3 and the density of the resin foam 24 is 40 kg/m 3 . 3 , and when the total thickness of the heat insulating material is 400 mm, it has been confirmed that the heat insulating material does not crack or peel even if the steel plate shrinks due to heat.

１ タイプＣの液化天然ガスタンク
１２ 圧力容器
１４ 架台
２０ 本発明の断熱材
２２ 樹脂発泡体
２４ 樹脂発泡体
２６ 補強層
１２１ 鋼板
４２ ガラスメッシュ 1 Type C liquefied natural gas tank 12 Pressure vessel 14 Frame 20 Insulating material of the present invention 22 Resin foam 24 Resin foam 26 Reinforcement layer 121 Steel plate 42 Glass mesh

Claims (7)

タイプＣの液化天然ガスタンクのタンク鋼板の外表面に設けられる断熱材であって、
前記断熱材は、樹脂発泡体を含み、
前記断熱材は、前記タンク鋼板側から外側に向かって８０ｋｇ／ｍ３～３０ｋｇ／ｍ３の範囲で前記樹脂発泡体の密度が減少する密度勾配を有し、
前記断熱材の厚さが、３００ｍｍ～５００ｍｍの範囲内である、
ことを特徴とする液化天然ガスタンク用断熱材。 A heat insulating material provided on the outer surface of a tank steel plate of a type C liquefied natural gas tank,
The heat insulating material includes a resin foam,
The heat insulating material has a density gradient in which the density of the resin foam decreases in a range of 80 kg/m 3 to 30 kg/m 3 from the tank steel plate side to the outside,
The thickness of the heat insulating material is within the range of 300 mm to 500 mm.
A heat insulating material for liquefied natural gas tanks characterized by: 前記樹脂発泡体が、ポリウレタンフォームであることを特徴とする請求項１に記載の液 化天然ガスタンク用断熱材。 The heat insulating material for a liquefied natural gas tank according to claim 1, wherein the resin foam is a polyurethane foam. 前記断熱材は、厚さ方向において密度が異なる樹脂発泡体の複数の層からなることにより、前記タンク鋼板側から外側に向かって前記樹脂発泡体の密度が段階的に減少する密度勾配を有することを特徴とする請求項１または２に記載の液化天然ガスタンク用断熱材。 The heat insulating material is composed of a plurality of layers of resin foam having different densities in the thickness direction, so that the heat insulating material has a density gradient in which the density of the resin foam gradually decreases from the tank steel plate side toward the outside. The heat insulating material for a liquefied natural gas tank according to claim 1 or 2, characterized by: 前記断熱材の厚さ方向と直交する方向に平面を有するように、ガラスメッシュが設けられてなることを特徴とする請求項１～３のいずれかに記載の液化天然ガスタンク用断熱材。 The insulating material for a liquefied natural gas tank according to any one of claims 1 to 3, characterized in that a glass mesh is provided so as to have a plane in a direction perpendicular to the thickness direction of the insulating material. タイプＣの液化天然ガスタンクのタンク鋼板の外表面に、樹脂発泡体を含む断熱材を設 ける断熱材形成工程を有し、
前記断熱材形成工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって８０ｋｇ／ｍ３～３０ｋｇ／ｍ３の範囲で前記樹脂発泡体の密度が減少する密度勾配を有し、
前記断熱材の厚さが、３００ｍｍ～５００ｍｍの範囲内である
ことを特徴とする液化天然ガスタンク用断熱材の施工方法。 It has a heat insulating material forming process in which a heat insulating material containing resin foam is provided on the outer surface of the tank steel plate of a Type C liquefied natural gas tank,
In the heat insulating material forming step, the heat insulating material has a density gradient in which the density of the resin foam decreases in a range of 80 kg/m 3 to 30 kg/m 3 from the tank steel plate side to the outside,
A method for constructing a heat insulating material for a liquefied natural gas tank, characterized in that the thickness of the heat insulating material is within a range of 300 mm to 500 mm. 前記樹脂発泡体が、ポリウレタンフォームであり、
前記断熱材形成工程は、前記ポリウレタンフォームを吹き付ける吹付工程を含み、
前記吹付工程は、密度の異なるポリウレタンフォームを複数回にわたり吹き付けて前記タンク鋼板の外表面に断熱材を形成するものであり、
前記吹付工程によって、前記断熱材は、前記タンク鋼板側から外側に向かって前記ポリウレタンフォームの密度が減少する密度勾配が形成される
ことを特徴とする請求項５に記載の液化天然ガスタンク用断熱材の施工方法。 The resin foam is polyurethane foam,
The heat insulating material forming step includes a spraying step of spraying the polyurethane foam,
The spraying step involves spraying polyurethane foam with different densities multiple times to form a heat insulating material on the outer surface of the tank steel plate,
The heat insulating material for a liquefied natural gas tank according to claim 5, wherein the spraying step forms a density gradient in the heat insulating material in which the density of the polyurethane foam decreases from the tank steel plate side toward the outside. construction method. 請求項２に記載の液化天然ガスタンク用断熱材が、タンク鋼板の外表面に設けられ、前記断熱材は、前記タンク鋼板側から外側に向かって前記ポリウレタンフォームの密度が減少する密度勾配を有することを特徴とするタイプＣの液化天然ガスタンク。 The heat insulating material for a liquefied natural gas tank according to claim 2 is provided on the outer surface of a tank steel plate, and the heat insulating material has a density gradient in which the density of the polyurethane foam decreases from the tank steel plate side toward the outside. A Type C liquefied natural gas tank featuring:
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Citations (3)

* Cited by examiner, † Cited by third party
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JP2000079987A (en) 1998-07-24 2000-03-21 Gaz Transport & Technigaz Improvement in impermeable insulated tank comprising assembled panel
JP2018176996A (en) 2017-04-13 2018-11-15 三井Ｅ＆Ｓ造船株式会社 Vessel
JP2019018512A (en) 2017-07-20 2019-02-07 旭化成建材株式会社 Resin foam composite body

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JPS5880071A (en) * 1981-11-02 1983-05-14 岡田　直樹 Construction of heatproof apparatus of tank

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000079987A (en) 1998-07-24 2000-03-21 Gaz Transport & Technigaz Improvement in impermeable insulated tank comprising assembled panel
JP2018176996A (en) 2017-04-13 2018-11-15 三井Ｅ＆Ｓ造船株式会社 Vessel
JP2019018512A (en) 2017-07-20 2019-02-07 旭化成建材株式会社 Resin foam composite body

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