JPH11270996A - Lng vaporizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LNG vaporizer that can easily perform PT inspection near the welding joint part of a heat transfer pipe and a lower header where a thermal load is repeatedly applied causing the problem of thermal fatigue strength and at the same time obtains a sacrifice anode effect due to the flame spraying covering of Al-Zn alloy or the like and further a sacrifice anode effect due to a sacrifice anode material. SOLUTION: In an LNG vaporizer 1, a panel 3 with an LNG channel and a cooling fin is welded between headers 6 and 7 being arranged up and down and sea water is allowed to flow down along the surface of the panel 3 for vaporizing LNG. In the LNG vaporizer 1, a welding joint part 5 between the lower header 7 and the panel 3 or an area 12 including the welding joint part 5 are allowed to remain as an inspection surface, and the flame spraying layer of a corrosion resistance metal covering 13 is executed to the entire surface of the upper and lower headers 6 and 7 and the panel 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LNG (liquefied natural gas) vaporizer, and more particularly, to LNG flowing in a heat transfer tube using seawater or the like as a heating medium to convert the LNG into NG (natural gas).
The present invention relates to an LNG vaporizer.

[0002]

2. Description of the Related Art An open rack type vaporizer (hereinafter referred to as an ORV) is usually used for vaporizing LNG. LNG is flowed in a heat transfer tube of the vaporizer, and seawater or the like (hereinafter, seawater is taken as an example) on an outer surface of the tube. NG conversion is performed by flowing seawater (described below).

FIG. 4 is an explanatory diagram showing a schematic configuration of a main part of the ORV. In the ORV, a panel 22 having a plurality of heat transfer tubes 21 arranged in a curtain shape and a panel unit 25 including an upper header 23 and a lower header 24 connected to the upper and lower portions of the panel 22 are arranged in parallel. At the same time, a trough 26 for flowing seawater W as a heat source is disposed above the panel 22 of each panel unit 25, and is basically configured. Seawater W as a heat source is a seawater header not shown.
The water is accumulated in each trough 26 through a watering nozzle, and overflows from the side edge of the trough 26 and flows down along the outer surface of the panel 22. The flowing seawater W is discharged to the outside through a seawater pool 27 below the panel 22. On the other hand, LNG is sent from the LNG manifold 28 to the LNG header 24,
Is heated and vaporized by this heating and rises,
The NG header 23 is guided to the NG manifold 29.

The panel 22 has a structure in which vertical heat-transfer tubes 21 having heat radiation fins formed on the outer surface thereof are usually arranged in a row. An Al alloy is generally used because workability for molding and high thermal conductivity are required.
However, since the Al alloy is susceptible to pitting in a seawater environment, a sacrificial anode film such as an Al-Zn alloy having a lower natural potential than the Al alloy is applied to the surface of the heat transfer tube 21 by thermal spraying for the purpose of preventing corrosion. In addition, the sacrificial anticorrosive action of the coating protects the Al alloy as a base material. (Japanese Unexamined Patent Publication No. 1-114698
No., Japanese Patent Publication No. 7-1157)

[0005] However, in the above-mentioned prior art, the sacrificial corrosion-preventing action of the coating of the Al-Zn alloy or the like sprayed on the surface can suppress the corrosion and erosion of the heat transfer tube made of the Al alloy as the base material. In the actual operation, there is the following problem since the aluminum alloy heat transfer tube at the counter electrode is prevented from corrosion by electrochemically dissolving, that is, being consumed by itself.

That is, a film of an Al—Zn alloy or the like serving as a sacrificial anode is formed by thermal spraying and is applied to the entire surface of the panel. At the connection with the lower part of the heat pipe and the lower header, as shown in FIG. 4b, the flowing seawater with the momentum collides, and is accelerated synergistically by the separation phenomenon due to the falling energy, so that the sprayed coating is quickly consumed. . When the thermal spray coating on the surface wears out, the heat transfer tube itself also wears and pits and loses its thickness, and it is not possible to maintain the structural strength as it is, so the spent thermal spray coating requires respraying each time. Become.

On the other hand, Japanese Patent Laying-Open No. 9-178391 proposes an LNG vaporizer in which the above problem is improved. In the proposed LNG vaporizer, the panel lower part and the lower header of the panel unit are immersed in seawater retained in a water receiving container or the like, and immersed in the lower header in seawater retained in the water receiving container or the like. The sacrificial anode is electrically connected, and the lower part of the panel and the lower header are immersed in seawater stagnated in a water receiving container, etc., so that the lower part of the heat transfer tube and the connection part with the lower header are connected. Can prevent direct spraying of the flowing seawater, prevent peeling of the sprayed coating on the part, and electrically connect the sacrificial anode, so that the lower header and the surface of the panel can be sprayed. This has the advantage that the wear of the coating and the corrosion of the heat transfer tube itself that occurs subsequently after the wear can be reduced.

[0008]

The conventional LN
As described above, the G vaporizer is provided with a thermal spray coating of an Al-Zn alloy or the like serving as a sacrificial anode on the entire panel including the upper and lower headers, and further by separately providing a sacrificial anode material.
Although the anti-corrosion effect of Al alloy panels has been greatly improved, the connection between the heat transfer tubes constituting the panels and the upper and lower headers is usually made by welding, while the heat transfer tubes are connected during the operation of the LNG vaporizer. Since a large heat load is repeatedly applied, the thermal fatigue strength particularly near the welded joint between the heat transfer tube and the lower header becomes a problem, and there is a concern that the heat tube portion may be cracked or damaged. However, as described above, the entire surface of the panel including the upper and lower headers is provided with a thermal spray coating of an Al-Zn alloy or the like serving as a sacrificial anode. LN)
At the site where the G vaporizer is installed, it is necessary to polish and remove the sprayed coating each time, and after the PT inspection, the sprayed coating must be applied again. The fact is that no inspection has been done.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a heat transfer tube and a lower header in the vicinity of a welded joint where heat load is repeatedly applied and thermal fatigue strength is problematic. A PT test can be easily performed, and A
It is an object of the present invention to provide an LNG vaporizer capable of enjoying a sacrificial anode effect by a thermal spray coating such as an l-Zn alloy, and furthermore, a sacrificial anode effect by a sacrificial anode material.

[0010]

In order to achieve the above object, an LNG vaporizer according to the present invention (claim 1) comprises a panel having an LNG flow path and a radiating fin between headers arranged vertically. In an LNG vaporizer, which is made by welding and allows seawater or the like to flow down along the surface of the panel to vaporize LNG, a weld joint between the lower header and the panel or the vicinity including the weld joint is left as an inspection surface. The thermal spray coating of the anticorrosion metal film is applied to the upper and lower headers and the entire panel.

[0011] In the structure of the LNG vaporizer, the Al-Zn alloy is located near the welded joint between the lower header and the panel or in the vicinity of the welded joint, particularly where thermal load is repeatedly applied and thermal fatigue strength is a problem. No need to remove the anticorrosion metal film prior to the PT inspection because there is no thermal spray coating of the anticorrosion metal film, etc. In each case, the PT inspection can be easily performed at the installation site, so that cracks, damages, and the like of the heat transfer tubes can be grasped before the damages are serious. Further, the thickness of the heat transfer tube can be measured without an error due to the thermal spray coating.

The LNG vaporizer according to the present invention (claim 2) is obtained by welding a panel having an LNG flow path and a radiating fin between headers arranged above and below, so that seawater or the like is spread along the surface of the panel. In an LNG vaporizer for vaporizing LNG by flowing down, a thermal spray prevention member is detachably provided in a welded joint between a lower header and a panel or in a vicinity including the welded joint, and an anticorrosive metal film is formed on the entire upper and lower headers and panel. It is formed by applying a thermal spray layer.

[0013] In the structure of the LNG vaporizer, the first aspect is as follows.
In comparison with the above, the thermal spray prevention member is detachably provided near the welded joint between the lower header and the panel or near the welded joint, so that when spraying the anticorrosion metal film, It can be performed without concern that spraying will occur, and when PT inspection is required, it can be easily performed at the installation site by removing it, thereby causing major damage such as cracks and damage of the heat transfer tube You can figure out before. Further, the thickness of the heat transfer tube can be measured without an error due to the thermal spray coating.

In the LNG vaporizer according to the second aspect, the thermal spray prevention member may be an adhesive tape or a sacrificial anode material. The latter case is preferable because an anticorrosion effect can be expected in the vicinity including the welded joint between the lower header and the panel.

Further, the above-mentioned (claim 1, 2 or 3) LN
In the G vaporizer, the lower header and the panel may be immersed in the water-receiving vessel, and the sacrificial anode material may be detachably attached to the immersion site. In addition to the effect, in the vicinity of the welded joint between the lower header and the panel, there is no direct collision of the vibrant seawater flowing down the panel surface, and the corrosion and erosion due to the seawater are reduced, which is preferable. .

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a schematic configuration of a main part of an ORV which is one embodiment of an LNG vaporizer according to the present invention, wherein a is a perspective view, and b is an X of a shown excluding a trough.
-X arrow view, c is a Y part enlarged explanatory view of b.

The entire structure of the LNG vaporizer 1 is basically the same as that of the conventional one, and a panel 3 in which a plurality of heat transfer tubes 2 made of Al alloy are arranged in a curtain shape, Panel units 8 composed of an aluminum alloy upper header 6 and a lower header 7 connected by welding to upper and lower parts (welded joints 4 and 5) are arranged in parallel, and the panel of each panel unit 8 is arranged. A trough 9 for letting seawater W flow down is provided above and between the three. In addition,
Reference numeral 10 denotes a lower manifold for supplying LNG, and 11 denotes an upper manifold for sending out vaporized NG.

Then, the panel unit 8 is arranged as shown in FIG.
As shown in FIGS. 2B and 2C, a thermal spray coating 13 of an Al—Zn alloy or the like is formed on the entire surface of the panel 3 except for the welded joint 5 between the heat transfer tube 2 and the lower header 7 and the vicinity 12 thereof.
It is needless to say that a sacrificial anode material or the like is attached to the welded joint portion 5 where the thermal spray coating 13 is not applied and its vicinity 12 at the time of practical use for corrosion prevention of the portion.

The operation of the LNG vaporizer 1 having the above-described structure is performed in the same manner as in the prior art as follows. That is, seawater W as a heat source is supplied and stored from a seawater header (not shown) through a branch supply pipe, overflows from the side edge of the trough 9, and flows down along both surfaces of the panel 3. Seawater W flowing down
Is discharged outside through a seawater pool (not shown) below the panel 3. On the other hand, LNG is the lower manifold 10
Is heated by the seawater W, is vaporized in the heat transfer tube 2 of the panel 3, rises as NG, and is guided from the upper header 6 to the upper manifold 11. The gas is sent to a gas line (not shown) via the manifold 11.

By the above operation, the heat load is repeatedly applied to the heat transfer tubes 2 of the panel 3 and the thermal fatigue strength becomes a problem.
In particular, a thermal spray coating 13 of an Al—Zn alloy or the like is not applied to the welded joint 5 between the lower header 7 and the heat transfer tube 2 of the panel 3, which is problematic due to its reduced thermal fatigue strength, and its vicinity 12. Therefore, not only the periodic inspection but also the PT inspection can be easily performed at the installation site whenever necessary. Further, the thickness of the heat transfer tube can be measured without an error due to the thermal spray coating.

In the above example, when the coating 13 of an Al--Zn alloy or the like is applied by thermal spraying, the thermal spraying is carried out except for the welded joint 5 between the lower header 7 and the heat transfer tube 2 of the panel 3 and the vicinity 12 thereof. Although the example has been described, the present invention is not limited to this example. For example, as shown in FIG. 2, the welded joint 5 between the lower header 7 and the heat transfer tube 2 of the panel 3 and the vicinity 12 thereof are provided. The thermal spray prevention member 14 may be sandwiched from both sides of the panel 3 and may be detachably attached by bolts and nuts (not shown). In this case, after the thermal spray prevention member 14 is mounted, the coating such as an Al—Zn alloy is formed. 13 can be sprayed,
Weld joint 5 between lower header 7 and heat transfer tube 2 of panel 3
And thermal spraying except for the vicinity 12 thereof is facilitated. In addition, as the weld joint 5, if it is only to facilitate thermal spraying,
An Al alloy block or a resin block of the same material as that of the heat transfer tube 2 or an adhesive tape may be used.
The lower header 7 and the panel 3 which are not sprayed by using a material which becomes a sacrificial anode such as n alloy are used.
The anti-corrosion effect of the welded joint 5 with the heat transfer tube 2 and the vicinity 12 thereof can be obtained.

In the above example, the panel unit 8
An example has been described in which the lower header 7, the welded joint 5, and the lower part of the panel 3 in the vicinity 12 are located above the sea surface of a seawater pool (not shown), but the present invention is limited to this example. Instead, for example, as shown in FIG. 3, they may be immersed and arranged in the seawater of the seawater pool 15 and the sacrificial anode material 16 may be removably attached to the immersion site. With the structure, in addition to the operation and effect of the above-described example, the seawater with the momentum flowing down on the surface of the panel 3 directly collides with the welded joint 5 with the lower header 7 and the panel 3 and the vicinity 12 thereof. This is preferable because corrosion and erosion due to seawater are reduced.

[0023]

As described above, the LN according to the present invention is
According to the G vaporizer, the PT inspection near the welded joint between the heat transfer tube and the lower header, in which the thermal load is repeatedly applied and the thermal fatigue strength becomes a problem while enjoying the sacrificial anode effect of the thermal spray coating of an Al-Zn alloy or the like. Can be easily performed at the installation site, as well as at regular intervals, as well as during periodic inspections, so that cracks, damages, and the like in the heat transfer tubes near the welded joint can be ascertained before significant damage occurs.

In addition, a thermal spray prevention member can be detachably provided near the welded joint between the lower header and the panel or in a vicinity including the welded joint. Thermal spraying can be performed without fear that thermal spraying will occur. In addition, when PT inspection is required, the PT inspection can be easily performed at the installation site by removing the thermal spray prevention member. Further, by forming the thermal spraying prevention member from a sacrificial anode material, it is possible to prevent corrosion in the vicinity of a welded joint where thermal spraying is not straightened. Also,
Since the PT inspection surface has no thermal spray coating, the thickness of the heat transfer tube can be measured without error by using the surface.

[Brief description of the drawings]

FIG. 1 is an embodiment of an LNG vaporizer according to the present invention;
It is explanatory drawing which shows the schematic structure of the principal part of RV, a is a perspective view, b is the XX arrow view of a shown except a trough, c is b
3 is an enlarged explanatory view of a Y part of FIG.

FIG. 2 is an explanatory view showing the vicinity of a welded joint according to another embodiment of the present invention.

FIG. 3 is an explanatory view showing the vicinity of a welded joint according to another embodiment of the present invention.

FIG. 4 is an explanatory view showing a schematic configuration of a main part of an ORV which is a conventional LNG vaporizer, wherein a is a perspective view and b is a Z- of FIG.
It is a Z sectional view.

[Explanation of symbols]

1: LNG vaporizer 2: Heat transfer tube
3: Panel 4: Upper weld joint 5: Lower weld joint
6: Upper header 7: Lower header 8: Panel unit
9: Trough 10: Lower manifold 11: Upper manifold 1
2: Near the weld joint 13: Thermal spray coating 14: Thermal spray prevention member 1
5: Seawater pool W: Seawater

Claims (5)

[Claims] 1. An LNG header is arranged between upper and lower headers.
In an LNG vaporizer in which a channel and a panel having a radiation fin are welded and seawater or the like flows down along the surface of the panel to vaporize LNG, a weld joint or a weld joint between the lower header and the panel is formed. An LNG vaporizer characterized in that a sprayed layer of an anticorrosive metal film is applied to the upper and lower headers and the entire panel while leaving the vicinity including the surface as an inspection surface. 2. An LNG header between upper and lower headers.
In an LNG vaporizer in which a channel and a panel having a radiation fin are welded and seawater or the like flows down along the surface of the panel to vaporize LNG, a weld joint or a weld joint between the lower header and the panel is formed. An LNG vaporizer characterized in that a thermal spraying preventive member is detachably provided in the vicinity thereof and a thermal spray layer of an anticorrosive metal film is applied to the upper and lower headers and the entire panel. 3. The LNG vaporizer according to claim 2, wherein the thermal spray prevention member is an adhesive tape. 4. The LNG vaporizer according to claim 2, wherein the thermal spraying prevention member is a sacrificial anode material. 5. The LNG vaporizer according to claim 1, 2 or 3, wherein the lower header and the panel are immersed in a water receiving container, and a sacrificial anode material is detachably attached to the immersion site. .