JPH07280186A - Portable type super low temperature liquefied gas container - Google Patents

Abstract

PURPOSE:To provide a portable type super low temperature liquefied gas container which can withstand the super low temperature, has the required pressure resistance and mechanical strength, and remarkably reduces the heat conduction compared with the conventional one. CONSTITUTION:In super low temperature liquefied gas container, a double shell structure consisting of the inner tank and the outer tank is provided, and the respective tanks are connected to each other through a neck tube 4, and the upper end of the neck tube 4 is welded to an outer tank flange of an outer tank top plate, and the lower end of the neck tube 4 is welded to an inner tank top plate respectively. The neck tube 4 to be used is made by bending a nickel- molybdenum alloy sheet with the symbol number NM1P(Grade 1) of JISH4551(1991) in a cylindrical shape, executing the butt welding of the seam to form a cylinder, and cutting the whole straight part 4b except the welded parts 4a, 4a on the upper and lower end side of the cylinder to the wall thickness of 0.4-0.9mm.

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 / consumption facility, and particularly to a stored ultra-low temperature liquefied gas container by significantly improving 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 is minimized.

[0002]

2. Description of the Related Art Portable ultra-low temperature liquefied gas containers have hitherto been widely used as convenient and portable storage and consumption equipment for ultra-low temperature liquefied gases such as liquefied nitrogen gas and liquefied oxygen gas. This portable ultra-low temperature liquefied gas container is specified in the high pressure gas control law, Container Safety Regulations, Article 7 No. 5 as materials, and in No. 6 as design elements such as allowable stress, and its overall structure is known. is there. FIG. 4 shows an overall view of a typical conventional (and present invention) portable ultra-low temperature liquefied gas container.

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

On the other hand, since the outer tank (2) is in contact with the outside air, it has the same outside air temperature (for example, 20 ° C.). Therefore, the temperature difference between the inner tank (1) and the outer tank (2) is 216-189.
Since the temperature reaches ℃, and the evaporation loss is large as it is, the stored liquefied nitrogen gas evaporates to the atmosphere within a short time and cannot be used for practical use.

Therefore, in order to prevent evaporation of liquefied nitrogen gas and the like, a heat insulating layer (5) (for example, 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 insertion and installation, a vacuum heat insulation system is adopted in which it is evacuated to a high vacuum and then sealed to reduce the evaporation loss of the stored liquefied nitrogen gas etc. and put it into practical use. Further, in this portable ultra-low temperature liquefied gas container, a neck tube (4) is used as a member for connecting the inner tank (1) and the outer tank (2), and the inner tube (1) is removed by the neck tube (4). The neck tube (4) is fixed to the tank flange (3) by being suspended and fixed, and the neck tube (4) is used as a communication opening for piping for inflow and outflow of ultra-low temperature liquefied gas. In order to prevent the inner tank (1) from swinging during transportation, the inner tank (1) bottom plate and outer tank should be
(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, from the viewpoints of securing the security during a suspension due to the recent spread of the two-day weekly holiday system and the extension of summer and winter vacations, and the economy. There is a strong demand from users to improve the heat insulation performance in order to reduce the amount of evaporation loss.

In order to meet this demand, the present inventors measured and analyzed the heat of invasion 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. The results shown in Table 1 below were obtained.

[0008]

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

From these results, in order to improve the heat insulation performance of the container, it is the most important issue to reduce the heat of penetration from the neck tube (4), which accounts for 56.3% of the total heat of penetration and most of the heat. I understand.

Now, the neck tube (4) is required to satisfy the following requirements (a) and (b) according to the High Pressure Gas Control Law. (A) Since it is a container that stores ultra-low temperature liquefied gas, use a material that can withstand the ultra-low temperature of -196 ° C (at 1 atm), which is the boiling point of liquefied nitrogen gas. (B) Since it is a container that stores and consumes ultra-low temperature liquefied gas under pressure (for example, 10 atm), it must have 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, nickel-chromium alloy (for example, J
Neck tube made of austenitic stainless steel pipe made of SUS304Tp etc. specified in IS G3459)
It is used as (4).

Therefore, the above-mentioned conventional stainless steel pipe was used to try to improve the heat insulating performance. However, the current stainless steel pipe is restricted because the condition (b) for ensuring the mechanical strength is satisfied. It has been found that the wall thickness of the neck tube (4) made of steel can be reduced to a small width, for example, 10% less than the current wall thickness, and there is a limit to the large improvement in heat insulation performance.

Under such circumstances, the present invention is a portable ultra-low temperature liquefaction which can withstand ultra-low temperature, has required pressure resistance and mechanical strength, and can significantly reduce the amount of heat penetration as compared with the conventional one. 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) by the outer tank flange of the top plate.
In (3), the lower end of the neck tube (4) is a cryogenic liquefied gas container having a structure in which each is welded to the inner tank (1) and the top plate.As the neck tube (4), a nickel-molybdenum alloy plate is cylindrical. After bending, the joints are butt-welded to form a cylinder, and the straight joints (4a) and (4a) excluding the weld joints (4a) and (4a) on the upper and lower ends of the cylinder are formed.
b) It is characterized in that it is made by cutting the whole to a predetermined wall thickness.

The present invention will be described in detail below with reference to the drawings.

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) as shown in FIG. Both tanks are connected via a neck tube (4), the upper end of the neck tube (4) is the outer tank flange (3) of the outer tank (2) and the lower end of the neck tube (4) is 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 communication opening for piping for inflow and outflow of ultra-low temperature liquefied gas.

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

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

In FIG. 4, (7) is a liquid extraction 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 above-mentioned neck tube (4), after bending a nickel-molybdenum alloy plate into a cylindrical shape, the joints are butt-welded to form a cylinder, and both upper and lower ends of the cylinder are formed. The whole straight portion (4b) excluding the welded portions (4a), (4a) on the side is cut to a predetermined wall thickness. This point is a feature of the present invention different from the conventional one.

The nickel-molybdenum alloy plate is JIS
It is standardized by H4551 (1991), and commercial products have the symbols NM1P (1 type) and NM2P (2 types). Their chemical compositions are shown below.

NM1P type: Nickel-molybdenum alloy plate type 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: 2 types of nickel-molybdenum alloy plate Chemical composition (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, among the above, the specific heat and thermal conductivity of the nickel-molybdenum alloy plate type 1 (NM1P) are set to SUS3 of the austenitic stainless steel pipe which has been conventionally used.
The results are shown in Table 2 in comparison with 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
The thermal conductivity can be reduced by 25% by using M1P. Since NM1P has a lower thermal conductivity than NM2P among the nickel-molybdenum alloy plates, NM1P can be used as a neck tube (4).
Is excellent.

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

[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 of conventional S
It can be seen that it can be calculated by increasing 50% of US304. Therefore, a neck tube that maintains the same mechanical strength as before
When manufacturing (4), the thickness applied to the conventional SUS304 can be greatly reduced.

The reduction of the wall thickness used is an important means as an acceleration factor for reducing the thermal conductivity peculiar to the material used by 25%. By adding these two factors, the heat insulation performance is greatly improved ( In other words, a large reduction in the amount of heat that enters 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 significant decrease in mechanical strength.
It is described in the American Society of Mechanical Engineers (ASME) standard "Boiler and Pressure Vessel Standard Section VIII, Subsection C and Table UNF-23.3".

As described above, it has been found that the nickel-molybdenum alloy plate has material properties far superior to those of the conventional austenitic stainless steel pipe as the material of the neck tube (4). The neck tube (4) is a material that has never been put to practical use for the purpose of ultra-low temperature liquefied gas containers, and there is no tubular standard product that can be obtained at low cost. went.

That is, a nickel-molybdenum alloy plate was bent into a cylindrical shape by using a roll winding machine, and then its joint was butt-welded by TIG welding or the like to form a cylinder. There are various welding rods that can be used for welding work at this time, but since it is necessary to add mechanical cutting processing in the subsequent process, it has the best molten metal flow characteristics to prevent pinholes and blowholes. There is JIS Y Ni Mo
It was found that JIS Y Ni Cr Mo-4 with Cr added to -7 was optimal.

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

On the other hand, the length of the neck tube (4) is 7
The wall thickness of the straight portion (4b), which accounts for 0% or more, can be put to practical use if it satisfies the mechanical strength above that regulated by the above-mentioned high-pressure gas control law. Therefore, NM1
For the purpose of reducing the wall thickness by cutting only the straight part (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 Specified Equipment Inspection Regulation of the High Pressure Gas Control Law. Was calculated.

The calculation of the wall 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, etc. Table 4 shows the wall thickness calculation results when
Shown in.

[0037]

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

In addition to the above calculated values, in reality, in addition to the above calculated values, the load calculation of various cryogenic liquefied gases having different liquid densities, the stress calculation values such as the vibration calculation at the time of transportation because it is a portable container, and further the processing accuracy. In consideration of, 0.40mm-0.9mm in practical use
The optimum thickness is.

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

As a result, a portable ultra-low temperature liquefied gas container in which the heat of invasion is minimized and the evaporation loss of the ultra-low temperature liquefied gas to be accommodated is also minimized is manufactured.

As the ultra-low temperature liquefied gas contained in the portable ultra-low temperature liquefied gas container, liquefied nitrogen gas, liquefied oxygen gas,
There are various ultra-low temperature liquefied gases such as liquefied argon, liquefied carbon dioxide and liquefied natural gas.

The portable ultra-low temperature liquefied gas container of the present invention is a portable and simple storage and consumption facility for various ultra-low temperature liquefied gases such as liquefied gas for welding cutting work and liquefied gas for encapsulation to prevent oxidation of food and drink. Is useful as

[0043]

In the portable ultra-low temperature liquefied gas container of the present invention, the neck tube for connecting the inner tank (1) and the outer tank (2)
As (4), after bending the nickel-molybdenum alloy plate into a cylindrical shape, the joints are butt-welded to form a cylinder, and the welded joints (4
Since the whole straight part (4b) excluding a) and (4a) was cut to the specified wall thickness, the heat insulation performance was significantly improved, and therefore the amount of heat intrusion was significantly higher than before. The evaporation loss of the ultra-low temperature liquefied gas is minimized as well. The neck tube (4) withstands ultra-low temperature and has necessary pressure resistance and mechanical strength.

[0044]

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

Embodiment 1 As described above, FIG. 1 is a vertical 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 typical conventional portable cryogenic liquefied gas container.

A nickel-molybdenum alloy plate (JIS H4551, NM1) is used as an alloy plate for producing the neck tube (4).
P) 's "Hastelloy B" from Mitsubishi Materials Corporation
A sheet having a plate thickness of 4.0 mm was prepared, and after bending this alloy plate into a cylindrical shape, the joints were butt-welded to form a cylinder (see FIG. 1). In FIG. 1, (x) is a welded portion.
At this time, using JIS Y Ni Cr Mo-4 as the welding rod,
TIG welding was performed while performing an argon gas back seal to form an airtight integral structure.

Next, prior to welding the cylindrical alloy plate to the inner tank (1) and the outer tank flange (4), the straight portion (4b) except the welded joint portions (4a), (4a) on both upper and lower end sides is welded. ) Cutting the entire outer peripheral portion to a wall thickness of 0.75 mm (see Fig. 2).

Neck tube produced in this way
(4) was attached to the inner tank (1) and the outer tank flange (4) as shown in FIG. That is, the inner tube (1) made of SUS304 and the outer tank flange (3) made of SUS304 are attached to the neck tube.
The welded joints (4a) and (4b) of (4) were circumferentially welded by TIG welding. In FIG. 3, (y) and (z) are circumferential welds at that time. Also in this case, JIS Y NiCr Mo-4 was used as the welding rod while performing the argon back-sealing so as to form an airtight double shell integral structure. Note that (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 placed in the container and the evaporation loss amount was measured. The measurement method complied with the high pressure gas control law container safety regulation related standard “insulation performance test of ultra-low temperature container”. The results at this time are shown in Table 5 together with the measured values under the same conditions of the existing container manufactured using the SUS304 neck tube (straight part thickness 1 mm) as a comparative control.

[0050]

[Table 5] Adiabatic performance test record Container of the present invention Existing container Test container Evaporation loss amount (g / day) Test container Evaporation loss amount (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

It can be seen from Table 5 that the evaporation loss amount of the portable ultra-low temperature liquefied gas container of the present invention is 65% of the evaporation loss amount of the existing container. Therefore, for the user who uses the container of the present invention, the usable amount of the ultra-low temperature liquefied gas that can be substantially used is increased, and the effective use of resources is achieved. In addition, the rate of increase in the internal pressure of the container decreases in proportion to the 35% decrease in evaporation loss, so that the safety aspect can be improved.

[0052]

In the portable ultra-low temperature liquefied gas container of the present invention, the material for 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 effect by selecting a nickel-molybdenum alloy plate with a much lower rate, the SUS of that alloy plate
Optimum cutting process is applied by taking advantage of the mechanical strength property which is much higher than 304 steel pipe, resulting in the minimum heat penetration amount. The amount can be significantly reduced.

Therefore, the portable cryogenic liquefied gas container of the present invention can be used to store and consume ultracold liquefied gas such as liquefied nitrogen gas, liquefied oxygen gas, liquefied argon, liquefied carbon dioxide gas and liquefied natural gas. On the other hand, economic loss due to evaporation loss can be greatly reduced, and safety can be ensured when evaporative gas is released into the atmosphere. Therefore, the present invention can greatly contribute to society.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a neck tube (4) of a portable cryogenic liquefied gas container of the present invention.

2 is a plan view of the neck tube (4) of FIG. 1. FIG.

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

FIG. 4 is an overall view of a typical portable cryogenic liquefied gas container of the present invention and the related art.

[Explanation of symbols]

 (1)… Inner tank, (2)… Outer tank, (3)… Outer tank flange, (4)… Neck tube, (4a)… Welding joint part, (4b)… Straight section, (5)… Insulation layer , (6)… Lower steady rest, (7)… Liquid take-out pipe, (8)… Liquid level gauge, (9)… Pressurizing coil, (10)… Handle ring, (11)… Foot ring, (w) , (x), (y), (z) ... Weld

Claims (3)

[Claims] 1. A double shell structure comprising an inner tank (1) and an outer tank (2), both tanks being connected via a neck tube (4), and the upper end of the neck tube (4) is an outer tank. (2) Outer tank flange on the top plate
In (3), the lower end of the neck tube (4) is a cryogenic liquefied gas container having a structure in which it is welded to the inner tank (1) and the top plate, respectively.As the neck tube (4), a nickel-molybdenum alloy plate is cylindrical. After bending, the joints are butt-welded to form a cylinder, and the entire straight portion (4b) except for the welded joints (4a), (4a) on both upper and lower ends of the cylinder has a predetermined wall thickness. A portable ultra-low temperature liquefied gas container, which is characterized by being cut. 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 (Type 1) of 4551 (1991) and a welding rod used for the welding is JIS Y Ni Cr 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 is 0.4 to 0.9 mm.