JP5088748B2 - Durable member and open rack type vaporizer using the same - Google Patents

Description

  The present invention relates to a heat transfer tube of an open rack type vaporizer, or a durable member used for a heat transfer tube and a lower header tube, and an open rack type vaporizer using the durable member.

  An open rack type vaporizer (hereinafter sometimes referred to as ORV) is applied to vaporize liquefied natural gas (hereinafter sometimes referred to as LNG). The ORV is a heat exchanger that vaporizes LNG by heat exchange with seawater, which is a heat source. 5A and 5B are schematic diagrams of a conventional ORV, in which FIG. 5A is a front view thereof, FIG. 5B is a cross-sectional view thereof, and FIG. 5C is a schematic diagram showing a welded joint between a heat transfer tube and a lower header tube. .

  As shown in FIGS. 5A and 5B, seawater is stored in the trough 170 in the ORV 200. The outer surface of the heat transfer panel (heat transfer tube panel) 110 formed by arranging a large number of heat transfer tubes 120 in a panel shape and joining to the header tubes (lower header tube 130 and upper header tube 140) is discharged from the trough 170. Seawater flows down from the top. On the other hand, LNG is sent to the lower header pipe 130 via the lower manifold 150, heated by heat exchange with seawater, and vaporized and raised in each heat transfer pipe 120 of the heat transfer panel 110. Then, natural gas is led out from the upper manifold 160 through the upper header pipe 140. Further, as shown in FIG. 5C, the lower portion of the heat transfer tube 120 is welded to the lower header tube 130.

  In the ORV heat transfer tube 120, the vicinity of the welded joint portion (including the welded portion) with the header tube (the lower header tube 130 and the upper header tube 140) is subjected to changes in the metal structure such as compound precipitation due to welding, and is corroded. It is often easy to do. In addition, the lower header pipe 130 and the lower part of the heat transfer panel 110 (lower part of the heat transfer pipe 120) on the LNG introduction side are dissolved because the seawater of the heating source is low temperature (about 0 ° C) due to LNG (about -160 ° C). The environment is highly corrosive due to high oxygen concentration. For this reason, wear due to corrosion in the vicinity of the weld joint between the heat transfer tube 120 and the lower header tube 130 is significant, which affects the life of the ORV 200. Further, as described above, the lower header pipe 130 and the lower part of the heat transfer pipe 120 on the LNG introduction side are exposed to extremely low temperatures (−160 ° C.) due to the vaporization of LNG, and the heat from there There is a very high possibility that the surface of the pipe that is in contact with seawater by conduction will be at a very low temperature. Further, since seawater due to heat exchange during LNG vaporization (during operation) is constantly applied to the lower header pipe 130 and the heat transfer panel 110, the lower header pipe 130 and the surface of the heat transfer panel 110 are worn out by so-called erosion-corrosion. Is inevitable.

Therefore, various proposals have been made regarding the anticorrosion technology of ORV.
For example, Patent Document 1 proposes a technique in which a sacrificial anticorrosive metal (Al—Zn alloy or the like) is formed on a heat transfer tube surface (aluminum base material surface) by thermal spraying or cladding, thereby improving the corrosion resistance.
Japanese Patent Laid-Open No. 5-16496

  However, in the case of anticorrosion by forming a sacrificial anticorrosive metal layer, the surface of the aluminum base material can be protected only by applying the sacrificial anticorrosive metal layer by thermal spraying at the lower header tube or the lower part of the heat transfer tube. In many cases, the metal layer was consumed so rapidly that it could not fully perform its function. Moreover, in the corrosion protection by thermal spraying, there is a problem that the weld joint is insufficiently sprayed or the sacrificial corrosion-resistant metal layer contains defects and corrodes. Furthermore, when using a material in which a sacrificial anticorrosive metal layer is formed of a clad, it is necessary to remove the sacrificial anticorrosive metal layer at the welded joint between the heat transfer tube and the header tube, and thus a separate anticorrosion treatment is required.

  Although it is possible to form anti-corrosion coating such as tar epoxy paint, at the lower header and the lower part of the heat transfer tube (especially near the welded joint between the heat transfer tube and the lower header tube) Since there is a problem that the anticorrosion paint freezes and peels due to the thermal cycle by repeating with normal temperature, there are few practical examples.

  Further, it is known that when there is a temperature difference between different types of conductors in contact with different types of conductors, a potential difference is generated between the conductors due to the Seebeck effect (thermoelectric effect). Even in the ORV, it is considered that a thermoelectromotive force is generated by the Seebeck effect between the lower header tube or the heat transfer tube (aluminum base material) and the sacrificial anticorrosive metal layer. Since the thermoelectromotive force generated between different types of conductors is small compared to the electromotive force generated in a semiconductor, there has been no example so far. However, a large temperature difference like an ORV occurs in a short distance, and the long-term When placed in the state, it was found that there was an acceleration of corrosion due to thermoelectric power. As described above, the consumption of the sacrificial anticorrosive metal layer in the lower header tube or the heat transfer tube lower part on the LNG introduction side where the tube surface is extremely low is considered to be due to the influence of the thermoelectromotive force.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is an open rack type vaporizer heat transfer tube, or a heat transfer tube and a lower portion, which are less susceptible to wear due to corrosion and excellent in cryogenic durability. An object of the present invention is to provide a durable member used for a header pipe and an open rack type vaporizer using the same.

The durable member according to the present invention is a durable member used as a heat transfer tube of an open rack type vaporizer that vaporizes liquefied natural gas by heat exchange with seawater as a heat source, or as a heat transfer tube and a lower header tube, A metal tubular base material, a sacrificial anticorrosive metal layer covering a part or all of the surface of the base material, and a surface of the sacrificial anticorrosive metal layer, when the open rack type vaporizer is operated, A conductive resin layer that covers at least both the low temperature portion and the high temperature portion that does not drop to the seawater coagulation temperature, and the electrical resistivity of the conductive resin layer is 1 × 10 ² Ωcm at 0 ° C. It is characterized by the following.

  According to the durable member used for such a heat transfer tube, the conductive material having at least a predetermined electrical resistivity, covering at least both the low temperature portion and the high temperature portion of the sacrificial anticorrosive metal layer covering the surface of the base material. By providing a resin layer, the thermoelectromotive force (charge) generated by the temperature difference between the sacrificial anti-corrosion metal layer on the side in contact with seawater and the substrate on the side in contact with liquefied natural gas during the operation of the open rack type vaporizer However, the conductive resin layer moves as an electronic bypass from a low temperature region where a large thermoelectromotive force is generated to a high temperature region where a small thermoelectromotive force is generated. Thereby, the thermoelectromotive force generated in the durable member used for the heat transfer tube is reduced, and wear due to corrosion due to the thermoelectric effect is suppressed.

  Further, according to the durable member used for such a heat transfer tube and the lower header tube, in addition to the action of the durable member used for the heat transfer tube, the durable member used for the lower header tube covers the surface of the substrate. By covering the sacrificial anticorrosive metal layer to be coated and providing a conductive resin layer having a predetermined electrical resistivity, the sacrificial anticorrosive metal layer on the side in contact with seawater during operation of the open rack vaporizer, and liquefaction Conductive resin layers of both tubes from the lower header tube where large thermoelectromotive force is generated to the heat transfer tube where small thermoelectromotive force is generated due to the temperature difference with the base material in contact with natural gas Moves as an electronic bypass. Thereby, the thermoelectromotive force generated in the durable member used for the lower header pipe is reduced, and wear due to corrosion due to the thermoelectric effect is suppressed.

The durable member according to the present invention further includes an organic resin layer covering the surface of the conductive resin layer, and the electrical resistivity of the organic resin layer is 1 × 10 ⁵ Ωcm or more at 0 ° C. It is characterized by.

  According to such a durable member, the sacrificial anticorrosive metal layer and the resin layer (conductive resin layer + organic) are provided by covering the conductive resin layer and further including an organic resin layer having a predetermined electrical resistivity. The standard electrode potential difference with the resin layer) is reduced, and galvanic corrosion occurring between the sacrificial anticorrosive metal layer and the resin layer is suppressed.

  An open rack type vaporizer according to the present invention is characterized in that the durable member according to claim 1 or 2 is used.

  According to such an open rack type vaporizer, by using the durable member, in the open rack type vaporizer, the thermoelectromotive force (charge) generated by the temperature difference between the sacrificial anticorrosive metal layer and the substrate is The conductive resin layer moves as an electronic bypass from the low temperature portion to the high temperature portion of the sacrificial anticorrosive metal layer. Thereby, the thermoelectromotive force generated in the open rack type vaporizer is reduced, and wear due to corrosion due to the thermoelectric effect is suppressed.

  In addition, by covering the conductive resin layer of the durable member with an organic resin layer having a predetermined electrical resistivity, the standard electrode potential difference between the sacrificial anticorrosive metal layer and the resin layer (conductive resin layer + organic resin layer) can be reduced. The galvanic corrosion generated by the sacrificial anticorrosive metal layer and the resin layer is suppressed.

  According to the durable member of the present invention, since the conductive resin layer covering the sacrificial anticorrosive metal layer on the surface of the substrate is provided, wear due to corrosion due to thermoelectromotive force is suppressed, and the cryogenic durability is excellent. It will be a thing. And it becomes possible to use for a heat transfer tube of an open rack type vaporizer, or a heat transfer tube and a lower header tube. Note that the conductive resin layer of the durable member does not cover the entire surface of the sacrificial anticorrosive metal layer, that is, the sacrificial anticorrosive metal layer has a portion that is not covered with the conductive resin layer. The heat exchange efficiency in the lower header pipe can be improved.

  Moreover, according to the durable member which concerns on this invention, since a durable member is further provided with the organic resin layer which coat | covers a conductive resin layer, galvanic corrosion is suppressed and cryogenic durability becomes still more excellent. .

  According to the open rack type vaporizer according to the present invention, since the durable member is used, wear due to corrosion caused by the thermoelectromotive force is suppressed, and the cryogenic durability is excellent. Note that the heat transfer tube or the conductive resin layer of the heat transfer tube and the lower header tube does not cover the entire surface of the sacrificial anticorrosive metal layer, that is, the portion where the sacrificial anticorrosive metal layer is not covered with the conductive resin layer. The heat exchange efficiency in the open rack type vaporizer can be improved.

  Moreover, according to the open rack type vaporizer | carburetor which concerns on this invention, since a durable member (a heat exchanger tube or a heat exchanger tube and a lower header tube) further comprises the organic resin layer which coat | covers a conductive resin layer, a galvanic corrosion is carried out. It is suppressed and the cryogenic durability is further improved.

Next, a durable member and an open rack type vaporizer according to the present invention will be described in detail with reference to the drawings.
In the drawings to be referred to, FIG. 1 is a schematic diagram showing a configuration of an open rack type vaporizer according to the present invention, FIG. 2 is a perspective view showing a configuration of a durable member used in a heat transfer tube, and FIG. 2) is a cross-sectional view in the tube axis direction of FIG. 2, (b) is a cross-sectional view in the tube axis direction showing another embodiment of the durable member, and FIG. 4 shows the configuration of the durable member used in the lower header tube. It is sectional drawing of the pipe-axis direction shown.

≪Durable material≫
The durable member according to the present invention is used for a heat transfer tube of an open rack type vaporizer, or a heat transfer tube and a lower header tube. First, the durable member used for the heat transfer tube will be described.
As shown in FIGS. 1, 2, and 3 (a), the durable member used for the heat transfer tube 20 includes a base material 21, a sacrificial anticorrosive metal layer 22, and a conductive resin layer 23. Each configuration will be described below.

<Base material>
The base material 21 is made of a metallic tubular member. The material of the base material 21 is not particularly limited as long as it is used for a heat transfer tube of an open rack type vaporizer. Usually, a JIS standard 3000 series, 5000 series, or 6000 series aluminum alloy is used. .

<Sacrificial anticorrosive metal layer>
The sacrificial anticorrosive metal layer 22 covers part or all of the surface of the substrate 21.
Note that covering a part of the surface means that the base material 21 is sacrificed if the durable member can exhibit the extreme low temperature durability without covering the entire surface of the base material 21 with the sacrificial anticorrosive metal layer 22. There may be a portion that is not covered with the anticorrosion metal layer 22, and there may be a portion where the substrate 21 is exposed.

  The method for coating the sacrificial anticorrosive metal layer 22 is to use a metal having a natural potential in seawater (high ionization tendency) with respect to the metal constituting the substrate 21 and spraying (frame spraying, electric type). Spraying, high-speed flame spraying, etc.) or cladding. As the metal constituting the sacrificial anticorrosive metal layer 22, for example, when the metal constituting the substrate 21 is made of an aluminum alloy, an Al—Zn alloy, an Al—Mg alloy, an Al—Zn—Mg alloy, or the like may be used. it can. Moreover, when using an Al-Zn alloy, an Al-2 mass% Zn alloy is mentioned, for example. The thickness of the sacrificial anticorrosive metal layer 22 is not particularly specified, but may be about several tens of μm to several mm.

<Conductive resin layer>
The conductive resin layer 23 covers at least both the low temperature portion 22a and the high temperature portion 22b in the sacrificial anticorrosive metal layer 22. By providing the conductive resin layer 23, the thermoelectromotive force generated by the temperature difference between the base material 21 and the sacrificial anticorrosive metal layer 22 covering the surface is reduced by the conductive resin layer 23 being an electronic bypass. can do. As a result, wear due to corrosion due to the thermoelectric effect of the durable member can be suppressed, and the durability at the cryogenic temperature of the durable member is improved.

Here, the low temperature part 22a is a part which becomes below the seawater coagulation temperature due to heat conduction of LNG (extremely low temperature: T ₀ ° C) supplied from the lower header pipe 30 to the inside of the heat transfer pipe 20 during operation of the ORV 100. It corresponds to the surface portion of the sacrificial anticorrosive metal layer 22 that covers the lower portion of the heat transfer tube 20 (T ₁ ° C., the portion where LNG is not vaporized). And the high temperature site | part 22b is a site | part which does not fall to seawater coagulation temperature, when LNG which distribute | circulates the inside of a pipe | tube is vaporized by the heat exchange with the seawater supplied to the pipe outer surface of the heat exchanger tube 20 at the time of operation of ORV100. T ₂ ° C.) corresponding to the surface portion of the sacrificial anticorrosion metal layer 22 covering the top of the heat transfer tube 20.

The low temperature portion 22a has a large temperature difference between the base material 21 (T ₀ ° C) and the sacrificial anticorrosion metal layer 22 (T ₁ ° C), and the thermoelectromotive force between the base material 21 and the sacrificial anticorrosion metal layer 22 is large. It is a part that grows. The high-temperature portion 22b has a small (no) temperature difference between the base material 21 (T ₃ ° C: temperature after LNG vaporization) and the sacrificial anticorrosive metal layer 22 (T ₂ ° C), and the base material 21 and the sacrificial anticorrosive metal. This is the site where the thermoelectromotive force between the layer 22 is small (can be eliminated).

  And by providing the conductive resin layer 23 covering at least the low temperature portion 22a and the high temperature portion 22b, that is, covering the sacrificial anticorrosion metal layer 22 (heat transfer tube 20) in a wide range, the low temperature portion 22a. The charge on the outer surface side of the sacrificial anticorrosive metal layer (part having a large temperature difference) can be released to the outer surface side of the sacrificial anticorrosive metal layer in the high temperature part 22b (part having a small temperature difference) through the conductive resin layer 23. That is, the conductive resin layer 23 has an electronic bypass effect.

  Even through the sacrificial anticorrosive metal layer 22, the charge is considered to move from a portion having a large temperature difference to a portion having a small temperature difference. However, the sacrificial anticorrosive metal layer 22 includes an oxide, pores, and a penetrating sealant, and is inferior in conductivity, so that the amount of charge transfer is small.

  In order to exhibit the above-described electron bypass effect, the conductive resin layer 23 covers the entire sacrificial anticorrosive metal layer 22 as long as both the low temperature portion 22a and the high temperature portion 22b of the sacrificial anticorrosive metal layer 22 are covered. There is no need. The shape of the conductive resin layer 23 is preferably a net shape or a porous shape having an opening 24 that does not cover the sacrificial anticorrosive metal layer 22.

  The higher the coverage of the sacrificial anticorrosive metal layer 22 by the conductive resin layer 23, the higher the thermoelectromotive force suppression effect by the electronic bypass effect, but the heat exchange efficiency of the ORV 100 is lowered. Therefore, by forming the opening (non-covering portion) 24 in the conductive resin layer 23, a decrease in the heat exchange efficiency of the ORV 100 is suppressed. Further, since the conductive resin layer 23 has the opening (non-covered portion) 24, the conductive resin layer 23 can be easily coated on the base material 21 (sacrificial anticorrosive metal layer 22) having a complicated shape.

  The area ratio of the opening (non-covered portion) 24 of the conductive resin layer 23 (net-shaped or porous conductive resin layer 23) is preferably 50 area% or more. The thickness of the net-like or porous conductive resin layer 23 is preferably 0.01 to 5 mm. If the thickness is less than 0.01 mm, the strength of the conductive resin layer 23 tends to be reduced. When the thickness exceeds 5 mm, the heat exchange efficiency at the portion covered with the conductive resin layer 23 is likely to be lowered, and the base material 21 (sacrificial anticorrosion metal layer 22) having a complicated shape is covered with the conductive resin layer 23. It becomes difficult to do.

  The conductive resin constituting the conductive resin layer 23 is a composite material in which a conductive material is added (contained) to an organic resin. The type of the organic resin is not limited, and for example, various resins such as polyethylene, polypropylene, polystyrene, acrylonitrile, fluorine, nylon, polyester, polyvinyl alcohol, and unsaturated polyester are used. The type of the conductive material is not limited, and for example, carbon black, carbon fiber, carbon nanomaterial, metal / alloy particles, and the like are used.

  The content of the conductive material is preferably 1 to 30% by mass. When the conductive material is less than 1% by mass, it is difficult to control the electrical resistivity of the conductive resin layer 23 described later to a predetermined value or less. When the conductive material exceeds 30% by mass. The stability, moldability and durability at cryogenic temperatures as a conductive resin tend to be impaired.

  The conductive resin layer 23 is not limited to a single layer composed of a conductive resin, and may be composed of a plurality of layers composed of a conductive resin. In the case of multiple layers, the second layer or more is composed of conductive resins containing the same type of organic resin but containing different conductive materials in the organic resin (reducing or not including conductive materials). It is preferable because a multilayer is easy.

The conductive resin layer 23 has an electrical resistivity of 1 × 10 ² Ωcm or less at 0 ° C. When the electrical resistivity exceeds 1 × 10 ² Ωcm, the above-described electron bypass effect is not exhibited, the thermoelectromotive force at the low temperature portion 22a of the sacrificial anticorrosive metal layer 22 is increased, and wear due to corrosion is promoted.

  And the electrical resistivity of conductive resin itself or the conductive resin layer 23 can be measured with a commercially available electrical resistivity meter or electrical conductivity meter. The electrical resistivity of the conductive resin layer 23 (the electrical resistivity at the surface of the conductive resin layer 23) can also be measured by the double ring electrode method of JISK6911 or the four probe method of JISK7194. The electrical conductivity value of the conductive resin layer 23 may be measured by any method as long as it is a single layer, but in the case of multiple layers, the latter method is used.

  Although the coating method of the conductive resin layer 23 is not particularly limited, for example, the following method is recommended.

(1) The conductive resin solution is applied to the sacrificial anticorrosive metal layer 22 by a usual method such as dipping, brushing, spraying or the like.

(2) A sheet or film made of a conductive resin is adhered to the sacrificial anticorrosive metal layer 22. Further, when forming the net-like or porous conductive resin layer 23, a thread made of conductive resin is knitted into a net-like or porous shape, or a sheet or film made of conductive resin is net-like. Or what was shape | molded in the porous shape should just be wound around the sacrificial anticorrosion metal layer 22, and may be stuck.

(3) A sheet or film made of a conductive resin is bonded to the sacrificial anticorrosive metal layer 22 by thermal bonding, solder bonding, adhesive, or the like. Further, when forming the net-like or porous conductive resin layer 23, a thread made of conductive resin is knitted into a net-like or porous shape, or a sheet or film made of conductive resin is net-like. Or what was shape | molded by the porous shape should just be adhere | attached on the sacrificial anticorrosion metal layer 22. FIG.

  When bonding is performed using a different material such as solder or adhesive, the different material is a material that is more conductive (has a lower electrical resistivity) than the conductive resin, and the sacrificial anticorrosive metal layer 22 It is necessary that the material has low galvanic corrosion.

  In the case where the sacrificial anticorrosive metal layer 22 is a thermal spray coating, the outer surface of the thermal spray coating may be coated with the conductive resin layer 23. However, when a sealing agent (sealing coating) is applied to the outer surface of the thermal spray coating. It is necessary to coat the outer surface of the thermal spray coating with the conductive resin layer 23 and apply a sealing film to the outer surface of the conductive resin layer 23. However, since the sealing film is worn early due to erosion-corrosion by seawater or freezing and the sprayed coating is exposed, the outer surface of the sprayed coating may be covered with the conductive resin layer 23 after the exposure.

  As shown in FIG. 3 (b), the durable member used for the heat transfer tube 20 according to the present invention includes the conductive resin layer 23 in addition to the base material 21, the sacrificial anticorrosive metal layer 22 and the conductive resin layer 23. You may provide the organic resin layer 25 which coat | covers the surface of these.

As described above, the lower the electrical resistivity of the conductive resin layer 23 can exhibit the electron bypass effect. However, if the electrical resistivity is lowered, there is a possibility that galvanic corrosion with the sacrificial anticorrosive metal layer 22 becomes a problem. Therefore, the surface of the conductive resin layer 23 (the surface not in contact with the sacrificial anticorrosive metal layer 22) is preferably covered with an organic resin layer 25 having an electrical resistivity of 0 ° C. of 1 × 10 ⁵ Ωcm or more. .

<Organic resin layer>
The organic resin layer 25 is composed of a composite material obtained by adding (containing) a conductive material to an organic resin. The kind of the organic resin or the conductive material is not limited, and for example, the organic resin or the conductive material described in the conductive resin layer 23 is used. Then, an organic resin or a conductive material is appropriately selected so that the electric resistivity of the organic resin layer 25 is 1 × 10 ⁵ Ωcm or more. The thickness of the organic resin layer 25 is preferably 10 mm or less. When the thickness exceeds 10 mm. The heat exchange efficiency in the portion covered with the organic resin layer 25 is likely to be lowered, and the conductive resin layer 23 having a complicated shape is hardly covered with the organic resin layer 25.

Next, the durable member used for the heat exchanger tube and the lower header tube according to the present invention will be described.
As shown in FIGS. 1 and 4, the durable member used for the lower header tube 30 includes a base material 31, a sacrificial anticorrosive metal layer 32, and a conductive resin layer 33. Moreover, the durable member used for the heat exchanger tube 20 is the same as that described above.

  The base material 31, the sacrificial anticorrosive metal layer 32, the conductive resin layer 33, and the organic resin layer 35 are composed of the base material 21, the sacrificial anticorrosive metal layer 22, the conductive resin layer 23, and the durable member used in the heat transfer tube 20. Since it is the same as the organic resin layer 25, description is abbreviate | omitted.

  The conductive resin layer 33 covers a part or the entire surface of the sacrificial anticorrosive metal layer 32. Here, covering a part of the surface means that the sacrificial anticorrosive metal can be used as long as the durable member can exhibit the extreme low temperature durability during the operation of the ORV 100 without covering the entire surface of the sacrificial anticorrosive metal layer 32. This refers to a state where the layer 32 may have a portion not covered with the conductive resin layer 33. Specifically, in the lower header tube 30, a portion near both ends thereof, a portion where the heat transfer tube 20 is not welded, or an opening 34 when the conductive resin layer 33 is formed in a net shape or a porous shape. In other words, there may be a portion where the sacrificial anticorrosive metal layer 32 is exposed.

  In order for the durable member used for the lower header tube 30 to exhibit cryogenic durability during operation of the ORV 100, the conductive resin layer 33 is electrically connected to the conductive resin layer 23 of the heat transfer tube 20. Thus, it is necessary to cover the surface of the sacrificial anticorrosive metal layer 32. The sacrificial anticorrosive metal layer 32 corresponds to the low temperature portion 22a (see FIG. 3A) in the sacrificial anticorrosive metal layer 22 of the durable member used for the heat transfer tube 20.

And by providing the conductive resin layer 33, the electromotive force (charge) generated by the large temperature difference between the base material 31 (T ₀ ° C) and the sacrificial anticorrosive metal layer 32 (T ₁ ° C) is converted into the conductive resin. When the layer 33 becomes an electron bypass, the conductive resin layer 23 of the heat transfer tube 20 (specifically, as shown in FIG. 3A, the conductive resin that covers the high temperature portion 22 b of the sacrificial anticorrosive metal layer 22). It is possible to escape to layer 23). As a result, wear due to corrosion due to the thermoelectric effect of the durable member (lower header tube 30) can be suppressed, and the cryogenic durability of the durable member is improved.

≪Open rack type vaporizer≫
As shown in FIG. 1, an open rack type vaporizer 100 according to the present invention uses the above-described durable member, and specifically includes a heat transfer tube 20 using the above-described durable member. Alternatively, the heat transfer tube 20 and the lower header tube 30 using the above-described durable member are provided. Although not shown, if the open rack type vaporizer 100 includes the heat transfer tube 20 using the above-described durable member, the lower header tube is sacrificed on the surface of a conventional lower header tube (for example, an aluminum alloy tube). A lower header pipe having a corrosion-resistant metal layer may be provided. When the open rack type vaporizer 100 includes the heat transfer tube 20 using the above-described durability member, or the heat transfer tube 20 and the lower header tube 30, the cryogenic durability of the open rack type vaporizer 100 is improved.

  As the open rack type vaporizer 100, the configuration of the open rack type vaporizer generally used except that the heat transfer tube 20 using the above-described durable member or the heat transfer tube 20 and the lower header tube 30 is provided. For example, the configuration shown in FIGS. 1, 2, and 4 may be used.

That is, in the open rack type vaporizer 100, a large number of heat transfer tubes 20 produced using the durable member of the present invention are arranged in a panel shape, and a lower header tube in which LNG is introduced below the heat transfer tubes 20. 30 is welded and joined to form a heat transfer tube panel 10, and an upper header tube 40 from which vaporized LNG (natural gas) is led is welded and joined to the upper portion of the heat transfer tube panel 10 (heat transfer tube 20). The lower header pipe 30 is provided with a lower manifold 50 that controls the introduction of LNG, and the upper header pipe 40 is provided with an upper manifold 60 that controls the derivation of natural gas. And the trough 70 which supplies seawater to the outer surface of the heat exchanger tube 20 is arrange | positioned at the upper part of the heat exchanger tube 20, and the seawater supplied from the trough 70 flows down the outer surface of the heat exchanger tube 20 from the top to the bottom. Then, heat exchange is performed with LNG flowing through the inside of the heat transfer tube 20.
In the heat transfer tube panel 10, the heat transfer tube 20 and the lower header tube 30 are welded so that the conductive resin layer 23 of the heat transfer tube 20 and the conductive resin layer 33 of the lower header tube 30 are electrically connected. It is joined. Specifically, after the heat transfer tube 20 (base material 21 + sacrificial anticorrosion metal layer 22) and the lower header tube 30 (base material 31 + sacrificial anticorrosion metal layer 32) are welded, the conductive resin layer 23 and the conductive resin layer are joined. Preferably 33 is formed.

Examples of the present invention are shown below.
A tube made of aluminum alloy A5083 and having a thickness of 5 mm and an inner diameter of 100 mm was cut to a length of 300 mm, and one opening was welded to an aluminum alloy A5083 plate of the same thickness to produce a cylindrical base material. The outer peripheral surface and the outer bottom surface of the substrate are roughened by shot blasting (alumina # 16 to # 20), and the outer surface is coated with a 300 μm thermal spray coating (sacrificial anticorrosive metal layer) made of an Al-2 mass% Zn alloy. (The inner surface was not coated with a thermal spray coating.) And a sample (Experiment No. 6) was obtained. Moreover, the resin sheet after hole-drilling was wound around the outer surface of the sample (Experiment No. 6) as a conductive resin layer, and fixed tightly to obtain samples (Experiment No. 1, 2, 7, 8). Further, a resin paint was applied in a mesh form as a conductive resin layer on the outer surface of the sample (Experiment No. 6), and dried sufficiently to obtain samples (Experiment No. 3-5, 9, 10). . The sample (Experiment No. 5) was applied (dried) twice with the resin solution.

  Here, the following conductive resin was used for the resin sheet or the resin paint. Commercially available carbon black (manufactured by Lion Corporation: Ketjen Black (registered trademark) EC600JD), commercially available fluororesin (manufactured by Fuji Kasei Kogyo: ZX-007-C), metal primer resin (manufactured by Showa Polymer Co., Ltd .: Lipoxy (Registered trademark) RT-833DA) was added in an amount of 0 to 20% by mass and kneaded to obtain a conductive resin. As the resin sheet, a conductive resin was formed into a sheet having a thickness of 0.1 to 3 mm using an extrusion molding machine, and then a hole was formed. The resin coating was applied by brush coating in a mesh shape with a thickness of 0.01 to 0.3 μm.

  About the sample (Experiment No. 1-10) produced as mentioned above, the coating method of a conductive resin layer, carbon black content (addition amount), 0 degreeC electrical resistivity, thickness, and coverage are shown in Table 1. Shown in Further, the cryogenic durability of each sample was evaluated by the following procedure, and the results are shown in Table 1.

(Evaluation of cryogenic durability)
Artificial seawater whose temperature was adjusted to 30 ° C. was put in a water tank, and the sample (Experiment No. 1 to 10) was placed therein, so that artificial seawater circulated on the outer peripheral surface. Contacts were attached to the outer peripheral surface and inner peripheral surface of the sample (attachment position was 20 mm height), liquid nitrogen was continuously added to the inside of the sample to a height of 200 mm for 10 minutes, and the potential difference between the contacts was measured. Of the potential differences measured during the addition of liquid nitrogen, the cryogenic durability of each sample was evaluated based on the maximum potential difference. When the addition of liquid nitrogen was stopped, liquid nitrogen evaporated, the temperature difference between the inner and outer peripheral surfaces disappeared, and the potential difference became zero.

  And in the evaluation results (see Table 1), in the sample not having the conductive resin layer (Experiment No. 6), a potential difference of 0.36 mV at maximum occurs, and the thermoelectric effect may cause wear due to corrosion. “×” indicates low durability at cryogenic temperature. For the samples (Experiment Nos. 1 to 5, 7 to 10), compared with the sample (Experiment No. 6), if the maximum potential difference is reduced by 10% or more, “C” with high cryogenic durability, If the maximum potential difference is less than 10% reduction or equivalent, “×” indicates low cryogenic durability.

From the results of Table 1, it was confirmed that the samples (experiment Nos. 1 to 5) as examples were superior in durability at cryogenic temperatures as compared to the sample (experiment No. 6) as a comparative example. . On the other hand, a sample (experiment No. 7 to 10) as a comparative example in which the electrical resistivity of the conductive resin layer is higher than that of the example (exceeds 1 × 10 ² Ωcm) is extremely low compared to the example. It was confirmed that the durability was inferior.

  As described above, the durable member according to the present invention and the open rack type vaporizer using the durable member have been described in detail with reference to the best mode and examples, but the gist of the present invention is limited to the contents described above. The scope of rights should be broadly interpreted based on the claims. Needless to say, the contents of the present invention can be widely modified and changed based on the above description.

It is the schematic which shows the structure of the open rack type vaporizer | carburetor which concerns on this invention. It is a perspective view which shows the structure of the durable member used for the heat exchanger tube which concerns on this invention. (A) is sectional drawing of the pipe-axis direction of FIG. 1, (b) is sectional drawing of the pipe-axis direction which shows other embodiment of a durable member. It is sectional drawing of the pipe-axis direction which shows the structure of the durable member used for the lower header pipe | tube which concerns on this invention. It is the schematic of the conventional open rack type vaporizer | carburetor, (a) is the front view, (b) is the sectional drawing, (c) is a schematic diagram which shows the welding joint part of a lower header pipe | tube and a heat exchanger tube. .

Explanation of symbols

10 Heat transfer panel (heat transfer tube panel)
20 Heat transfer tube (durable member)
21 Base material 22 Sacrificial anticorrosive metal layer 22a Low temperature part 22b High temperature part 23 Conductive resin layer 30 Lower header pipe (durable member)
31 Substrate 32 Sacrificial anticorrosive metal layer 33 Conductive resin layer 100 Open rack type vaporizer (ORV)

Claims (3)

A heat transfer tube of an open rack type vaporizer that vaporizes liquefied natural gas by heat exchange with seawater as a heat source, or a durable member used as a heat transfer tube and a lower header tube,
A metallic tubular substrate;
A sacrificial anticorrosive metal layer covering a part or all of the surface of the substrate;
On the surface of the sacrificial anticorrosive metal layer, a conductive resin layer that covers at least both a low temperature portion that is equal to or lower than the seawater coagulation temperature and a high temperature portion that does not drop to the seawater coagulation temperature when the open rack type vaporizer is operated; With
The durable member, wherein the electrical resistivity of the conductive resin layer is 1 × 10 ² Ωcm or less at 0 ° C. 2. The durability according to claim 1, further comprising an organic resin layer covering a surface of the conductive resin layer, wherein the electrical resistivity of the organic resin layer is 1 × 10 ⁵ Ωcm or more at 0 ° C. Sexual member.   An open rack type vaporizer using the durable member according to claim 1 or 2.

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