JP2582042B2 - Portable ultra-low temperature liquefied gas container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable ultra-low temperature liquefied gas container used as a movable storage and consumption equipment, and more particularly to a ultra-low temperature liquefied gas stored by significantly improving the heat insulation performance as compared with conventional containers. The present invention relates to a portable ultra-low temperature liquefied gas container in which the evaporation loss of the gas is minimized.

[0002]

2. Description of the Related Art A portable ultra-low temperature liquefied gas container has been widely used as a simple and portable storage and consumption facility for ultra-low temperature liquefied gas such as liquefied nitrogen gas and liquefied oxygen gas. In this portable ultra-low temperature liquefied gas container, the material is specified in Article 7, item 5 of the High Pressure Gas Control Law, and the design elements such as allowable stress are specified in item 6, and the entire structure itself is known. is there. FIG. 4 shows an overall view of a typical portable ultra-low temperature liquefied gas container of the related art (and the present invention).

In the portable ultra-low temperature liquefied gas container shown in FIG. 4, the temperature of the ultra-low temperature liquefied gas contained in the inner tank (1) varies depending on the internal pressure during storage. -196 ° C (at 1 atm) to -169 ° C
(At 10 atm), inner tank in contact with liquefied nitrogen gas
(1) is also cooled to the same ultra-low temperature.

On the other hand, the outer tank (2) has the same temperature as the outside air (for example, 20 ° C.) because it is in contact with the outside air. Therefore, the temperature difference between the inner tank (1) and the outer tank (2) is 216-189.
° C, and the evaporation loss is large if it is used as it is, so that the contained liquefied nitrogen gas evaporates to the atmosphere in a short time, and is not practical.

In order to prevent evaporation of liquefied nitrogen gas and the like, a heat insulating layer (5) (for example, a super insulation material) is provided in the hollow portion of the double shell structure of the inner tank (1) and the outer tank (2). After inserting and installing, a vacuum heat insulation system is adopted in which high vacuum evacuation is performed and then sealing is performed. In addition, in this portable ultra-low temperature liquefied gas container, a neck tube (4) is used as a member connecting the inner tank (1) and the outer tank (2), and the inner tank (1) is removed by the neck tube (4). The neck tube (4) is suspended and fixed to the tank flange (3), and the neck tube (4) is used as a communication opening for piping for inflow and outflow of ultra-low temperature liquefied gas. Note that the inner tank (1) bottom plate and outer tank
(2) A lower steady rest (6) is provided between the bottom plate and the bottom plate.

[0006]

When the portable ultra-low temperature liquefied gas container described above is used in view of the recent spread of the two-day work week and the securing of security during suspension due to the prolongation of summer and winter vacations and the economic aspect. There is a strong demand from users for improving the heat insulation performance to reduce the amount of evaporation loss.

[0007] In order to meet this demand, the present inventors have measured and analyzed the heat invading into the inner tank (1) from each part of the existing ultra-low temperature liquefied gas container as part of the technical development for improving the heat insulation performance. Was performed, the results shown in the following Table 1 were obtained.

[0008]

[Table 1] Heat penetration from each part of the container to the inner tank (1) Heat penetration part Heat penetration (kcal / h) Ratio (%) Penetration from neck tube (4) 4.96 56.3 From heat insulation layer (5) Penetration 3.37 38.3 Penetration from bottom steady rest (6) 0.48 5.4 Penetration heat in the whole container 8.81 100

From these results, it is the most important issue to improve the heat insulation performance of the container to reduce the invasion heat from the neck tube (4), which accounts for 56.3% of the total infiltration heat and the majority thereof. You can see that.

The neck tube (4) is required to satisfy the following requirements (a) and (b) according to the High Pressure Gas Control Law. (A) Since the container contains an ultra-low temperature liquefied gas, a material that can withstand an ultra-low temperature of -196 ° C. (in the case of 1 atm), which is the boiling point of liquefied nitrogen gas, is used. (B) Since it is a container for storing and consuming an ultra-low temperature liquefied gas under pressure (for example, 10 atm), it has a pressure resistance. Furthermore, it must have the mechanical strength necessary to hold the load of the inner tank and the load of the ultra-low temperature liquefied gas contained therein.

Conventionally, as a material satisfying both the conditions (a) and (b), a nickel-chromium alloy (for example, J
Austenitic stainless steel pipe made of SUS304Tp specified in IS G3459)
Used as (4).

[0012] To improve the heat insulation performance using the above-mentioned conventional stainless steel pipe, there is a restriction that the condition (b) for ensuring mechanical strength is satisfied. The wall thickness of the neck tube (4) made of stainless steel can be reduced to a small value, for example, 10% less than the current wall thickness, and it has been found that there is a limit to a large improvement in heat insulation performance.

Under such a background, the present invention provides a portable ultra-low temperature liquefaction that can withstand ultra-low temperatures, have the required pressure resistance and mechanical strength, and can significantly reduce the amount of heat infiltration as compared with the prior art. It is intended to provide a gas container.

[0014]

The portable ultra low temperature liquefied gas container of the present invention has a double shell structure of an inner tank (1) and an outer tank (2), and both tanks have a neck tube (4). The upper end of the neck tube (4) is connected to the outer tank (2).
(3) The lower end of the neck tube (4) is formed by welding a nickel-molybdenum alloy plate as the neck tube (4) in an ultra-low temperature liquefied gas container having a structure welded to the inner tank (1) top plate. After the bending process, the joints are butt-welded to form a cylinder, and the straight portion (4) except for the welded joints (4a) and (4a) at the upper and lower ends of the cylinder is formed.
b) The whole is machined to a predetermined thickness.

Hereinafter, the present invention will be described in detail with reference to the drawings.

As shown in FIG. 4, the portable ultra-low temperature liquefied gas container of the present invention has a double shell structure of an inner tank (1) and an outer tank (2). Both tanks are connected via a neck tube (4) .The upper end of the neck tube (4) is connected to the outer tank (2), the outer tank flange (3) of the top plate, and the lower end of the neck tube (4) is connected to the inner tank (1). ) Each is welded to the top plate. That is, the inner tank (1) is suspended and fixed to the outer tank flange (3) by the neck tube (4). The neck tube (4) also serves as a pipe communication opening for inflow and outflow of ultra-low temperature liquefied gas.

A heat insulating layer (5) (for example, a super insulation material) is inserted and installed in the hollow portion of the double shell structure composed of the inner tank (1) and the outer tank (2). Sealed from.

In order to prevent the inner tank (1) from swaying during transportation or handling, a lower steady rest (6) is provided between the bottom plate of the inner tank (1) and the bottom plate of the outer tank (2).

In FIG. 4, (7) is a liquid discharge pipe, (8) is a liquid level gauge,
(9) is a holding coil, (10) is a handle ring, and (11) is a foot ring.

In the present invention, as the neck tube (4), a nickel-molybdenum alloy plate is bent into a cylindrical shape, and its joint is butt-welded to form a cylinder. The entire straight portion (4b) excluding the welded joint portions (4a) and (4a) on the side is machined to a predetermined thickness. This is a feature of the present invention that is different from the related art.

The nickel-molybdenum alloy plate is JIS
It is standardized by H4551 (1991), and commercially available products include the symbols NM1P (1 type) and NM2P (2 types). The chemical composition is shown below.

NM1P Type: Nickel-molybdenum alloy sheet 1 Chemical composition (unit:%): Ni: balance, Cr: 1.0 or less, Fe:
4.0-6.0, Mo… 26.0-30.0, Cu…-, Mn… 1.0 or less, Co
… 2.5 or less, C… 0.05 or less, W…-, Si… 1.0 or less, P
… 0.04 or less, S… 0.03 or less, Al…-, Ti…-, V… 0.2
-0.4, Nb + Ta…-

NM2P Type: Nickel-molybdenum alloy plate 2 Chemical components (unit:%): Ni: balance, Cr: 1.0 or less, Fe:
2.0 or less, Mo… 26.0-30.0, Cu…-, Mn… 1.0 or less, Co
… 1.0 or less, C… 0.02 or less, W…-, Si… 0.10 or less, P
… 0.04 or less, S… 0.03 or less, Al…-, Ti…-, V…-,
Nb + Ta…-

Next, the specific heat and thermal conductivity of one of the above-mentioned nickel-molybdenum alloy plates (NM1P) were measured using the SUS3 of austenitic stainless steel tube conventionally used.
Table 2 shows a comparison with No. 04.

[0025]

[Table 2] Thermal conductivity type NM1P SUS304 specific heat (cal / g. ℃) 0.09 0.12 Thermal conductivity (kcal / mhdeg) 7.5 10.0

That is, the nickel-molybdenum alloy plate N
By using M1P, the thermal conductivity can be reduced by 25%. Since the thermal conductivity of the nickel-molybdenum alloy plate NM1P is smaller than that of NM2P, NM1P is used as the neck tube (4).
Is excellent.

Further, Table 3 shows the tensile strength of the nickel-molybdenum alloy sheet NM1P, which is the basis of the mechanical strength, in comparison with SUS304 used conventionally.

[0028]

[Table 3] Mechanical strength type NM1P SUS304 tensile strength (kg / mm ² ) 81.0 or more 53 or more 0.2% proof stress (kg / mm ² ) 35.2 or more 20.9 or more

That is, the nickel-molybdenum alloy plate N
By using M1P, the mechanical strength can be reduced by the conventional S
It can be seen that the calculation can be performed with a 50% increase from US304. Therefore, a neck tube that retains the same mechanical strength as before
When (4) is manufactured, the thickness applied to the conventional SUS304 can be greatly reduced.

The reduction of the used wall thickness is an important means for accelerating the reduction of the thermal conductivity inherent in the used material by 25%, and the addition of these two elements greatly improves the heat insulation performance ( That is, a large decrease in the amount of invading heat is realized.

Further, the nickel-molybdenum alloy plate is a material that can be used even at an extremely low temperature of, for example, -196 ° C. without causing a large decrease in mechanical strength.
It is described in the American Society of Mechanical Engineers (ASME) standard "Boiler and Pressure Vessel Standards Section VIII, Subsection C and Table UNF-23.3".

As described above, it has been found that the nickel-molybdenum alloy plate is much superior to the conventional austenitic stainless steel tube as a material of the neck tube (4) in each characteristic value. Neck tube (4) is a material that has never been used for ultra-low temperature liquefied gas containers, and there is no standard tube product available at low cost. went.

That is, after the nickel-molybdenum alloy plate was bent into a cylindrical shape using a roll winding machine, the joint was butt-welded by TIG welding or the like to form a cylinder. There are various types of welding rods that can be used for welding at this time, but since it is necessary to add mechanical cutting in a later step, the flow characteristics of the molten metal for preventing pinholes and blowholes are the best. A JIS Y Ni Mo
It has been found that JIS Y Ni Cr Mo-4 obtained by adding Cr to -7 is optimal.

As for the shape of the neck tube (4), FIGS. 1 and 2 show a longitudinal sectional view and a plan view of the neck tube (4) used in the present invention, and FIG. 3 shows the neck tube (4).
As shown in the installation drawing, the weld joints on the upper and lower ends of the neck tube (4) to be welded to the inner tank (1) and outer tank (2)
(4a) and (4a) need to be thick joints in order to maintain welding strength.

On the other hand, in the lengthwise direction of the neck tube (4),
The thickness of the straight portion (4b) occupying 0% or more can be put to practical use as long as it satisfies the above-mentioned mechanical strength regulated by the High Pressure Gas Control Law. Therefore, NM1
In order to reduce the wall thickness by cutting only the straight portion (4b) of the thick plate of P, the wall thickness is calculated by the calculation method described in Article 14, Paragraph 1, etc. of the High Pressure Gas Control Law specific equipment inspection rules. Was calculated.

The calculation of the thickness of the straight portion (4b) varies depending on factors such as the design capacity of the container, the type of ultra-low temperature liquefied gas to be stored, the design pressure, and the like. Table 4 shows the wall thickness calculation results when
Shown in

[0037]

[Table 4] Straight part wall thickness calculation result Design pressure (A) 15kg / cm ² (B) 26kg / cm ² Minimum thickness + thread height + decay allowance 0.23mm 0.40mm

Actually, in addition to the above-mentioned calculated values, load calculation of various kinds of ultra-low temperature liquefied gas containing different liquid densities, stress calculation values such as vibration calculation at the time of transportation because of a portable container, and processing accuracy Is added, practically 0.40mm ~ 0.9mm
Thickness is optimal.

The welded joints (4a), (4a) at the upper and lower ends of the neck tube (4) shown in FIGS.
a) is welded to the inner tank (1) and the outer tank flange (4) by TIG welding or the like as shown in FIG. 3 to produce an airtight double shell structure composed of the inner and outer tanks. A heat insulation layer (5) such as a well-known super-insulation material is inserted and installed in advance in the hollow part of the double shell structure, and high vacuum evacuation is performed from the exhaust port attached to the outer tank (2), and then vacuum sealing Stop.

As a result, a portable ultra-low temperature liquefied gas container can be manufactured in which the amount of heat intrusion is minimized, and the evaporation loss of the ultra-low temperature liquefied gas contained therein is also minimized.

The ultra-low temperature liquefied gas contained in the portable ultra-low temperature liquefied gas container includes liquefied nitrogen gas, liquefied oxygen gas,
Various ultra-low temperature liquefied gases including liquefied argon, liquefied carbon dioxide, and liquefied natural gas can be mentioned.

The portable ultra-low temperature liquefied gas container of the present invention is a portable and convenient storage and consumption equipment for various ultra-low temperature liquefied gases such as a liquefied gas for welding cutting work and a liquefied gas for sealing to prevent oxidation of food and drink. Useful as

[0043]

According to the portable ultra-low temperature liquefied gas container of the present invention, a neck tube connecting the inner tank (1) and the outer tank (2) is provided.
(4) After bending a nickel-molybdenum alloy plate into a cylindrical shape, the joints are butt-welded to form a cylinder, and the welded joints (4
Since the entire straight part (4b) excluding (a) and (4a) has been cut to a predetermined thickness, the heat insulation performance has been significantly improved, and the heat intrusion has been significantly reduced compared to the conventional type. At the same time, the evaporation loss of the cryogenic liquefied gas is minimized. The neck tube (4) withstands extremely low temperatures and has the required pressure resistance and mechanical strength.

[0044]

The present invention will be further described with reference to the following examples.

Embodiment 1 As described above, FIG. 1 is a longitudinal sectional view of the neck tube (4) of the portable ultra-low temperature liquefied gas container of the present invention, and FIG. 2 is a plan view thereof. FIG. 3 is a mounting view of the neck tube (4). FIG. 4 is an overall view of the present invention and a conventional portable ultra-low temperature liquefied gas container.

As an alloy plate for producing the neck tube (4), a nickel-molybdenum alloy plate (JIS H4551, NM1
P) "Hastelloy B" of Mitsubishi Materials Corporation
Was prepared, the alloy plate was bent into a cylindrical shape, and the joint was butt-welded to form a cylinder (see FIG. 1). In FIG. 1, (x) is a weld.
At this time, JIS Y Ni Cr Mo-4 was used as the welding rod,
TIG welding was performed while performing argon gas back sealing to obtain an airtight integrated structure.

Next, prior to welding the cylindrical alloy plate to the inner tank (1) and the outer tank flange (4), the straight portion (4b) excluding the welded joints (4a) and (4a) at the upper and lower ends. ) The entire outer peripheral part was reduced to a thickness of 0.75 mm by cutting (see Fig. 2).

The neck tube thus manufactured
(4) was attached to the inner tank (1) and the outer tank flange (4) as shown in FIG. That is, the neck tube is attached to the inner tank (1) made of SUS304 and the outer tank flange (3) made of SUS304.
The circumferentially welded portions (4a) and (4b) of (4) were welded by TIG welding. In FIG. 3, (y) and (z) are circumferential welds at that time. Also in this case, JIS Y NiCrMo-4 was used as a welding rod while performing an argon back seal so as to form an airtight double shell integrated structure. (W) is the outer tank (2) −
This is the weld between the outer tank flanges (4).

After the portable ultra-low temperature liquefied gas container of the present invention was completed in this way, liquefied nitrogen gas as an example of the ultra-low temperature liquefied gas was accommodated in the container, and the amount of evaporation loss was measured. The measurement method was based on the high-pressure gas control law vessel security regulation related standard "insulation performance test of ultra-low temperature vessel". The results at this time are shown in Table 5 together with the measured values under the same conditions of an existing container manufactured using a SUS304 neck tube (straight wall thickness 1 mm) as a control.

[0050]

[Table 5] Insulation performance test record Existing container of the present invention Test container Evaporation loss (g / day) Test container Evaporation loss (g / day) No. 1 1,146 No. 1 '1,674 No. 2 1,087 No. 2 '1,701 No. 3 1,056 No. 3' 1,681 No. 4 1,072 No. 4 '1,648 No. 5 1,048 No. 5' 1,656 Average 1,082 Average 1,672 Ratio 0.65 1.0

From Table 5, it can be seen that the evaporation loss of the portable ultra-low temperature liquefied gas container of the present invention is only 65% of the evaporation loss of the existing container. Therefore, for the user using the container of the present invention, the amount of the ultra-low temperature liquefied gas that can be substantially used is increased, and the resources are effectively used. In addition, since the rate of increase in the internal pressure of the container is proportionally reduced in accordance with the 35% reduction in the evaporation loss, the safety is improved.

[0052]

In the portable ultra-low temperature liquefied gas container of the present invention, the material of the neck tube (4) connecting the inner tank (1) and the outer tank (2) is more heat conductive than the conventional SUS304 steel pipe. In addition to the thermophysical properties effect of selecting a nickel-molybdenum alloy plate with a much lower rate, the SUS
By applying the optimum cutting process by utilizing the mechanical strength characteristics much higher than that of 304 steel pipe, the minimum amount of heat infiltration was realized. The amount can be significantly reduced.

Therefore, the portable ultra-low temperature liquefied gas container of the present invention can be used in a wide range of industries that store and consume ultra-low temperature liquefied gas such as liquefied nitrogen gas, liquefied oxygen gas, liquefied argon, liquefied carbon dioxide gas, and liquefied natural gas. On the other hand, the economic loss due to the evaporation loss can be greatly reduced, and the safety when the evaporative gas is released to the atmosphere can be ensured. Therefore, the present invention can greatly contribute to society.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a neck tube (4) of a portable ultra-low temperature liquefied gas container of the present invention.

FIG. 2 is a plan view of the neck tube (4) of FIG.

FIG. 3 is a mounting view of the neck tube (4) of FIG. 1;

FIG. 4 is an overall view of the present invention and a conventional portable ultra-low temperature liquefied gas container.

[Explanation of symbols]

 (1) ... inner tank, (2) ... outer tank, (3) ... outer tank flange, (4) ... neck tube, (4a) ... welded joint, (4b) ... straight part, (5) ... heat insulating layer , (6)… Lower steady rest, (7)… Liquid outlet pipe, (8)… Liquid level gauge, (9)… Holding coil, (10)… Handle ring, (11)… Foot ring, (w) , (x), (y), (z)… weld

Claims (3)

(57) [Claims] An inner tank (1) and an outer tank (2) have a double shell structure, both tanks are connected via a neck tube (4), and the upper end of the neck tube (4) is an outer tank. (2) Top plate outer tank flange
In (3), the lower end of the neck tube (4) is formed by welding a nickel-molybdenum alloy plate as the neck tube (4) in an ultra-low temperature liquefied gas container having a structure welded to the inner tank (1) top plate. After bending, the joint is butt-welded to form a cylinder, and the entire straight portion (4b) except for the welded joints (4a) and (4a) at the upper and lower ends of the cylinder is formed to a predetermined thickness. A portable ultra-low temperature liquefied gas container characterized by using a material that has been cut to the maximum. 2. The nickel-molybdenum alloy plate is JIS H
The portable ultra-low temperature liquefied gas container according to claim 1, which has a symbol number NM1P (1 kind) of No. 4551 (1991) and the welding rod used for the welding is JIS Y NiCr Mo-4. 3. The thickness of the straight portion (4b) after cutting is
The portable ultra-low temperature liquefied gas container according to claim 1, which has a thickness of 0.4 to 0.9 mm.