High-pressure gas cylinder applied to liquid nitrogen environment and processing method of high-pressure gas cylinder

Abstract

The invention discloses a high-pressure gas cylinder applied to a liquid nitrogen environment and a machining method of the high-pressure gas cylinder, and relates to the technical field of high-pressure containers. The high-pressure gas cylinder applied to the liquid nitrogen environment comprises a high-pressure gas cylinder body and a coating layer coating the outer surface of the high-pressure gas cylinder body, the shell wall of the high-pressure gas cylinder body sequentially comprises a metal lining cylinder and a composite material layer from inside to outside, the coating layer and the composite material layer are bonded through low-temperature epoxy glue, and the metal lining cylinder is made of a metal material. The metal lining bottle is formed by bonding alloy metal powder and a chelating agent at high temperature. 3D printing is adopted for the metal lining bottle, and spiral winding and annular winding are adopted for the composite material layer. By means of the design, the safety performance and stability of the gas cylinder in the liquid nitrogen environment can be effectively improved, meanwhile, the weight of the gas cylinder can be reduced, the service life of the gas cylinder is prolonged, and the high engineering application value is achieved.

Description

Technical Field

[0001] The present application relates to a high-pressure gas cylinder for use in a liquid nitrogen environment and a processing method thereof, and belongs to the technical field of high-pressure containers. Background Art

[0002] High-pressure gas cylinders are containers for storing compressed gas and are widely used in various fields, especially in scientific research and industrial applications under liquid nitrogen environments. Gas cylinders are usually processed using stamping, heat treatment, welding, machining and other process methods. The welding forming technology is to split the high-pressure gas cylinder to be manufactured into several main parts and then machine them together, and then use welding to connect these parts together to form a high-pressure gas cylinder.

[0003] On the one hand, this method has a long production cycle and is accompanied by serious material waste during the manufacturing process. On the other hand, welding technology, as a special processing method, is difficult to control, and stress concentration will occur at the junction of the weld and the substrate, causing the pressure bearing capacity of the entire weld to be lower than that of the substrate, which limits the improvement of pressure vessel professional technology to a certain extent. There are also problems such as pollution of materials by harmful substances in unwelded and heat treatment and the amount of metal cutting during machining, which leads to high manufacturing costs. Summary of the invention

[0004] In order to solve the above problems, a high-pressure gas cylinder for use in a liquid nitrogen environment and a processing method thereof are provided, which can effectively improve the safety performance and stability of the gas cylinder in a liquid nitrogen environment, while also reducing the weight of the gas cylinder and increasing its service life.

[0005] The present invention provides the following scheme:

[0006] A high-pressure gas cylinder for use in a liquid nitrogen environment comprises a high-pressure gas cylinder body and a coating layer coated on the outer surface of the high-pressure gas cylinder body, the shell wall of the high-pressure gas cylinder body comprises a metal liner bottle and a composite material layer from the inside to the outside, the coating layer and the composite material layer are bonded by low-temperature epoxy adhesive, and the metal liner bottle is formed by high-temperature bonding of alloy metal powder and a chelating agent.

[0007] Optionally, the covering layer may be a carbon fiber layer.

[0008] Optionally, the chelating agent is a multifunctional carboxylate powder. Preferably, the specific component of the chelating agent is at least one of sodium citrate, tartrate, succinate and sodium ascorbate. Preferably, the chelating agent is sodium citrate.

[0009] Optionally, the alloy metal powder comprises, by mass fraction, 95.8-98.6% aluminum, 0.8-1.2% magnesium, 0.4-0.8% silicon, 0-0.7% iron, 0-0.4% copper, 0-0.15% manganese, 0-0.15% titanium, and 0-0.1% zinc. Specifically, the weight ratio of the chelating agent to the metal powder is 1:(5-9).

[0010] Optionally, the metal lined bottle includes a bottle body in the middle, an air inlet bottle mouth and a bottle bottom respectively arranged at two ends of the bottle body, and the air inlet bottle mouth and the bottle body are connected by a bottle shoulder arc transition.

[0011] Optionally, the bottle bottom is any one of an ellipsoidal shape, a disc shape or a hemispherical shape.

[0012] Optionally, the rated pressure of the metal lined bottle is 35-70Mpa.

[0013] According to another aspect of the present application, a method for processing any of the above-mentioned high-pressure gas cylinders for use in a liquid nitrogen environment is provided, comprising the following steps:

[0014] (1) According to the calculation formula:

[0015]

[0016] Calculate the wall thickness parameter δ of each section of the mouth, shoulder, body and bottom of the metal lined bottle under the design pressure;

[0017] δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure;

[0018] n: safety factor, which is a design parameter and is derived from usage requirements;

[0019] p: design working pressure;

[0020] D: Calculate the diameter of the pressure-bearing section;

[0021] σ: allowable stress of material;

[0022] K: 3D printing coefficient; specifically, the final value of K is between 2 and 6. Further, the wall thickness of the bottle mouth is greater than the thickness of the bottle body, and the wall thickness of the bottle shoulder is between the bottle mouth and the bottle body. For example, the thickness of the bottle shoulder gradually decreases from the bottle mouth toward the bottle body, and the thickness of the bottle bottom can be greater than or equal to the thickness of the bottle body. The specific thickness can be adjusted by those skilled in the art according to the application scenario of the gas cylinder.

[0023] (2) according to the wall thickness parameters δ of the bottle mouth, bottle shoulder, bottle body and bottle bottom obtained in step (1), a three-dimensional solid model of the high-pressure gas cylinder is designed using three-dimensional modeling software, and then the three-dimensional model is sliced ​​and layered using slicing software to obtain contour data of each cross section, and a laser selective melting molding device is used to mold the bottle body according to the contour data to obtain a bottle body;

[0024] (3) Wrapping the composite material layer around the outside of the metal-lined bottle.

[0025] Optionally, the composite material layer adopts a combination of circumferential and spiral linear winding of composite fibers; specifically, the composite fibers are spirally wound and circumferentially wound on the body of the metal lined bottle, the composite fibers are spirally wound at the mouth and bottom of the metal lined bottle, and the composite fibers are gradually spirally wound at the shoulder.

[0026] Optionally, the thickness ratio of the winding layer at the bottle shoulder to the winding layer at the bottle body is (1.2-1.5): 1. For example, the bottle shoulder may be thinned first and then thickened during the winding process.

[0027] Optionally, the ratio of the winding thickness of the winding layer at the bottle mouth and the bottle bottom to the winding thickness at the bottle body is (1.3-1.6):1.

[0028] Optionally, the thickness ratio of the wrapping layer at the bottom of the bottle to the wrapping layer at the bottle body is (1.0-1.2):1.

[0029] Optionally, the preparation method of the composite fiber includes the following steps: melt-blending the reinforcing fiber, styrene-butadiene-styrene block copolymer and lignin at a temperature of 120°C-180°C, then adding acrylonitrile copolymer to continue the reaction, and finally adding N,N-dimethylformamide to obtain a spinning solution, and spinning to obtain the composite fiber.

[0030] The mass ratio of the reinforcing fiber, the styrene-butadiene-styrene block copolymer and the lignin is 1:3-5:2-7, and the mass ratio of the acrylonitrile copolymer and the lignin is 2-3:1.

[0031] The reinforcing fiber is one or more of carbon fiber, aramid fiber or basalt fiber.

[0032] The reinforcing fibers prepared by this method can improve the compatibility with the metal liner and the strength of the composite material layer, thereby further improving the safety of the gas cylinder.

[0033] The beneficial effects of the present invention include but are not limited to:

[0034] 1. According to a high-pressure gas cylinder for use in a liquid nitrogen environment and a processing method thereof provided in this application, the extremely low temperature of liquid nitrogen will cause the metal material in the high-pressure gas cylinder to become very brittle, which may cause brittle fracture of the cylinder wall, thereby reducing the pressure resistance of the cylinder; in a liquid nitrogen environment, the seals and sealing materials in the high-pressure gas cylinder may become hard and brittle, resulting in a decrease in sealing performance and possible gas leakage; the temperature of liquid nitrogen is very low, and the gas in the high-pressure gas cylinder may condense into a liquid or even solidify into a solid in the part contacted by the liquid nitrogen, which may cause changes in the internal pressure of the cylinder and may even cause explosion or leakage; this application comprehensively considers factors such as materials, design and manufacturing process, which is helpful to improve the safety, reliability and durability of high-pressure gas cylinders for use in liquid nitrogen environments.

[0035] 2. According to the high-pressure gas cylinder for liquid nitrogen environment application and its processing method provided in this application, advanced three-dimensional modeling software design and laser selective melting molding technology are used to accurately manufacture high-pressure gas cylinders that meet the design requirements, ensuring the accuracy and consistency of the bottle body.

[0036] 3. According to a high-pressure gas cylinder for use in a liquid nitrogen environment and a processing method thereof provided in this application, the design parameters such as the winding thickness, winding angle and number of winding layers of the gas cylinder limiting winding layer are determined based on the grid theory, and the combined linear winding technology of the circumferential and spiral directions of the composite fibers is adopted. The tensile strength and impact resistance of the bottle body can be effectively enhanced, thereby improving the overall performance of the high-pressure gas cylinder.

[0037] 4. According to a high-pressure gas cylinder for use in a liquid nitrogen environment and a processing method thereof provided in this application, based on the ratio of the winding layer at the bottle shoulder, bottle mouth, and bottle bottom to the winding layer at the bottle body, the bottle body can have a suitable thickness at different positions, thereby evenly distributing the stress and improving the pressure resistance and impact resistance of the bottle body. DETAILED DESCRIPTION

[0038] In order to more clearly explain the overall concept of the present application, a detailed description is given below with reference to examples.

[0039] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0041] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicating orientation or positional relationships are based on orientation or positional relationships and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0043] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0045] Example 1

[0046] The embodiment of the present application discloses a manufacturing process of a metal-lined cylinder of a high-pressure gas cylinder, comprising the following steps:

[0047] According to the calculation formula:

[0048]

[0049] Calculate the wall thickness parameter δ of the mouth, shoulder, body and bottom of the metal-lined bottle under the design pressure

[0050] δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure;

[0051] n: safety factor, which is a design parameter and is derived from usage requirements;

[0052] p: design working pressure;

[0053] D: Calculate the diameter of the pressure-bearing section;

[0054] σ: allowable stress of material;

[0055] K: 3D printing coefficient. The final value of 3D printing coefficient K is between 2 and 6.

[0056] In the manufacturing process of high-pressure gas cylinders, the 3D printing coefficients of the bottle mouth, bottle shoulder, bottle body and bottle bottom are involved. Taking into account the characteristic requirements of laser selective melting technology, for example, laser selective melting of inclined structures greater than 45 degrees is basically unfeasible or costly, so the shape parameters are set according to engineering experience and assigned to the 3D printing coefficient. In addition, the formula also takes into account the hot melting of metal powder. Laser selective melting technology is different from traditional casting. Its characteristics require that the comprehensive influence of heat of different materials and structures on the material must be fully considered during structural design calculations. Therefore, based on engineering experience, the influence of metal hot melting is also assigned to the 3D printing coefficient.

[0057] In the casting process of metal-lined bottles, the 3D printing coefficients of the bottle mouth, bottle shoulder, bottle body and bottle bottom are mainly involved. Taking into account the characteristics of laser selective melting technology, such as laser selective melting of inclined structures greater than 45 degrees, which is basically impossible to achieve or the cost is high, the shape parameters are set according to engineering experience and assigned to the 3D printing coefficient; in addition, the formula also takes into account the hot melting of metal powder. Laser selective melting technology is different from traditional casting. Its characteristics require that different materials and the comprehensive influence of heat of different structures on materials must be fully considered in structural design calculations. Therefore, the influence of metal hot melting is also assigned to the 3D printing coefficient according to engineering experience.

[0058] According to the above formula, the design wall thickness parameter δ required for each section of the high-pressure gas cylinder under the design pressure is calculated, and the wall thickness parameter of the high-pressure gas cylinder is input into the laser selective melting forming equipment to form the bottle body. After the bottle body is produced, the existing conventional technology is used to perform subsequent finishing processing on the bottle body to improve the quality and processing accuracy of the bottle body.

[0059] In this embodiment, casting and subsequent performance test experiments of high-pressure gas cylinders with design pressures of 35MPa and 70MPa were carried out. The materials used in the casting were alloy metal powders of 95.8-98.6% aluminum, 0.8-1.2% magnesium, 0.4-0.8% silicon, 0-0.7% iron, 0-0.4% copper, 0-0.15% manganese, 0-0.15% titanium, and 0-0.1% zinc. The chelating agent was at least one of sodium citrate, tartrate, succinate, and sodium ascorbate. The experimental data are shown in the following table:

[0060] Example 2

[0061] On the basis of Example 1, the casting materials are changed. The materials used in casting are alloy metal powders of 95.8-98.6% aluminum, 0.8-1.2% magnesium, 0.4-0.8% silicon, 0-0.7% iron, 0-0.4% copper, 0-0.15% manganese, 0-0.15% titanium, 0-0.15% manganese, and 0-0.1% zinc. The chelating agent is one of sodium citrate, tartrate, succinate, and sodium ascorbate used in batches.

[0062] Example 3

[0063] Based on the metal lined bottle obtained in Examples 1 and 2, the fiber layer is wound, the composite fiber is spirally wound and hoop-wound at the body of the metal lined bottle, the composite fiber is spirally wound at the mouth and bottom of the metal lined bottle, the composite fiber is gradually spirally wound at the shoulder, the winding thickness ratio of the winding layer at the shoulder to the body is (1.2-1.5): 1; the winding thickness ratio of the winding layer at the mouth and bottom to the body is (1.3-1.6): 1. The bursting pressure of the gas cylinder is predicted using the fiber tensile fracture criterion.

[0064] Test example

[0065] The performance tests of Examples 1-3 were performed, and the results are shown in the following table:

[0066] The high-pressure gas cylinder obtained in Example 1 was tested. The materials used in casting were alloy metal powders of 97.2% aluminum, 1.0% magnesium, 0.6% silicon, 0.4% iron, 0.2% copper, 0.08% manganese, 0.06% titanium, 0.11% manganese, and 0.08% zinc, and the chelating agent was sodium citrate. Where r is the radius of the inner diameter of the bottle mouth.

[0067] Table 1

[0068]

[0069] As described in Table 1 above, the high-pressure gas cylinder manufactured by the laser selective melting molding technology and the subsequent finishing technology has the entire bottle body formed in one piece, with fast production speed and high material utilization rate. It can be input remotely and can realize the molding of 35-70MPa working pressure thin-walled high-pressure gas cylinders. In addition, the finishing technology is used to finish the bottle body to ensure the manufacturing quality of the high-pressure gas cylinder.

[0070] The materials used in casting are alloy metal powders of 97.2% aluminum, 1.0% magnesium, 0.6% silicon, 0.4% iron, 0.2% copper, 0.08% manganese, 0.06% titanium, 0.11% manganese, and 0.08% zinc. The chelating agents are sodium citrate, tartrate, succinate, and sodium ascorbate. The obtained high-pressure gas cylinders are subjected to compression tests. The results are shown in Table 2.

[0071] Table 2

[0072] raw materials Compressive modulus Compressive strength Sodium citrate 40.58MPa 0.88MPa Tartrate 39.21MPa 0.71MPa Succinate 36.15MPa 0.58MPa Ascorbic acid sodium salt 37.68MPa 0.62MPa

[0073] Chelating agents with more coordination sites favor the formation of Al-chelate complexes. The promoted chelation leads to stronger bonding between metal particles, thus increasing the mechanical strength of 3D printed objects. Objects printed using NaCit have the highest compressive strength and compressive modulus, which can meet the requirements of use in liquid nitrogen environments.

[0074] Based on the metal lined bottle obtained in Examples 1 and 2, the materials used in casting are alloy metal powders of 97.2% aluminum, 1.0% magnesium, 0.6% silicon, 0.4% iron, 0.2% copper, 0.08% manganese, 0.06% titanium, 0.11% manganese, and 0.08% zinc, and the chelating agents are sodium citrate; the thickness ratio of the winding layer at the bottle shoulder to the winding layer at the bottle body is (1.2-1.5): 1; the thickness ratio of the winding layer at the bottle mouth and the bottle bottom to the winding layer at the bottle body is (1.3-1.6): 1; the thickness ratio of the winding layer at the bottle bottom to the winding layer at the bottle body is (1.0-1.2): 1, and the fiber tensile fracture criterion is used to predict the bursting pressure of the gas cylinder. Specifically, the thickness ratio of the winding layer at the bottle shoulder to the winding layer at the bottle body is 1.2-1.4: 1, the winding is first thinned and then thickened, and the thickness ratio of the winding layer at the bottle bottom to the bottle body is 1.2: 1. The results are shown in Table 3.

[0075] Table 3

[0076]

[0077] As shown in Table 3, it can be seen that the bursting pressure of the gas cylinder of the present application is not less than 220 MPa. Through the metal lining and the reasonable design of the winding thickness ratio of the bottle shoulder, bottle mouth and bottle bottom to the winding thickness ratio of the bottle body, the bottle body can have a suitable thickness at different parts, thereby evenly distributing the stress and improving the pressure resistance and impact resistance of the bottle body.

[0078] Example 4

[0079] Based on Example 3, the main difference is that the preparation method of the composite fiber includes the following steps: melt blending carbon fiber, styrene-butadiene-styrene block copolymer and lignin at a mass ratio of 1:3:2 at a temperature of 150°C, then adding acrylonitrile copolymer to continue the reaction, and finally adding N,N-dimethylformamide to obtain a spinning solution, and spinning to obtain the composite fiber. The mass ratio of acrylonitrile copolymer to lignin is 2:1.

[0080] The composite fiber prepared in Example 4 was applied to the metal liner, and the performance of the gas cylinder was tested, as shown in Table 4.

[0081] Table 4

[0082]

[0083] In summary, the high-pressure gas cylinder for use in a liquid nitrogen environment prepared in the present application has a bursting pressure greater than the standard requirement of 157.5 MPa under a working pressure of 70 MPa, a higher safety factor, and a longer service life.

[0084] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0085] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A high-pressure gas cylinder for use in a liquid nitrogen environment, characterized in that: It includes a high-pressure gas cylinder body and a coating layer coated on the outer surface of the high-pressure gas cylinder body. The shell wall of the high-pressure gas cylinder body includes a metal liner bottle and a composite material layer from the inside to the outside. The coating layer and the composite material layer are bonded by low-temperature epoxy adhesive. The metal liner bottle is made of alloy metal powder and chelating agent bonded at high temperature.

2. The high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 1, characterized in that: The chelating agent is a multifunctional carboxylate powder. Furthermore, the specific component of the chelating agent is at least one of sodium citrate, tartrate, succinate and sodium ascorbate.

3. The high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 1, characterized in that: Calculated by mass fraction, the specific components of the alloy metal powder include: 95.8-98.6% aluminum, 0.8-1.2% magnesium, 0.4-0.8% silicon, 0-0.7% iron, 0-0.4% copper, 0-0.15% manganese, 0-0.15% titanium, and 0-0.1% zinc.

4. The high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 1, characterized in that: The metal lined bottle comprises a bottle body in the middle, an air inlet bottle mouth and a bottle bottom respectively arranged at two ends of the bottle body, and the air inlet bottle mouth and the bottle body are connected by a bottle shoulder arc transition.

5. The high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 1, characterized in that: The bottle bottom is any one of an ellipsoidal shape, a dish shape or a hemispherical shape.

6. The high-pressure gas cylinder according to claim 1, characterized in that: The rated pressure of the metal lined bottle is 35-70Mpa.

7. A method for processing a high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in any one of claims 1 to 6, characterized in that: The processing method comprises the following steps: (1) According to the calculation formula: Calculate the wall thickness parameter δ of each section of the mouth, shoulder, body and bottom of the metal lined bottle under the design pressure; δ: Design wall thickness, i.e. the minimum wall thickness that can withstand the design pressure; n: safety factor, which is a design parameter and is derived from usage requirements; p: design working pressure; D: Calculate the diameter of the pressure-bearing section; σ: allowable stress of material; K: 3D printing coefficient; (2) according to the wall thickness parameters δ of the bottle mouth, bottle shoulder, bottle body and bottle bottom obtained in step (1), a three-dimensional solid model of the high-pressure gas cylinder is designed using three-dimensional modeling software, and then the three-dimensional model is sliced ​​and layered using slicing software to obtain contour data of each cross section, and a laser selective melting molding device is used to mold the bottle body according to the contour data to obtain a bottle body; (3) Wrapping the composite material layer around the outside of the metal lined bottle.

8. The method for processing a high-pressure gas cylinder for use in a liquid nitrogen environment according to claim 7, characterized in that: The composite material layer adopts a combination of circumferential and spiral linear winding of composite fibers; preferably, the composite fibers are spirally wound and circumferentially wound on the body of the metal lined bottle, the composite fibers are spirally wound at the mouth and bottom of the metal lined bottle, and the composite fibers are gradually spirally wound at the shoulder.

9. The method for processing a high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 8, characterized in that: The thickness ratio of the winding layer at the bottle shoulder to the winding layer at the bottle body is (1.2-1.5):

1.

10. The method for processing a high-pressure gas cylinder for use in a liquid nitrogen environment as claimed in claim 8, characterized in that: The thickness ratio of the winding layer at the bottle mouth to the winding layer at the bottle body is (1.3-1.6):1.

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