CN115435182B

CN115435182B - Vacuum pipeline and preparation process thereof

Info

Publication number: CN115435182B
Application number: CN202211298618.1A
Authority: CN
Inventors: 杜国鑫; 高海妹; 赵焕章
Original assignee: Sichuan Air Separation Plant Group Co ltd
Current assignee: Sichuan Air Separation Plant Group Co ltd
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2023-01-06
Anticipated expiration: 2042-10-24
Also published as: CN115435182A

Abstract

The invention discloses a vacuum pipeline and a preparation process thereof, belonging to the technical field of pipelines, wherein the vacuum pipeline comprises an outer pipe and an inner pipe which are coaxially arranged, and an interlayer space is formed between the outer side wall of the inner pipe and the inner side wall of the outer pipe; the cylinder is positioned in the interlayer space, sleeved on the inner pipe, and two ends of the cylinder are connected with the inner pipe to form sealing; a filling space is formed between the inner side wall of the cylinder and the outer side wall of the inner pipe; the adsorbent bag is fixedly arranged in the filling space; the cylinder is provided with a plurality of through holes, and the through holes are plugged by thermoplastic materials so that the cylinder and the outer side wall of the inner tube form sealing; and (3) pumping the interlayer space to vacuum, heating to melt the thermoplastic material, opening all the through holes, adsorbing the interlayer space by the adsorbent bag, and maintaining the vacuum degree of the interlayer space. The preparation process is used for preparing the vacuum pipeline, the adsorbent of the vacuum pipeline can fully exert the function of the vacuum pipeline, the vacuum degree of the interlayer space at low temperature is kept, and the service life of the vacuum degree is prolonged.

Description

Vacuum pipeline and preparation process thereof

Technical Field

The invention relates to the technical field of pipelines, in particular to a vacuum pipeline and a preparation process thereof.

Background

An adsorbent is generally disposed in a sandwich space of a vacuum low-temperature heat insulation pipe (hereinafter referred to as a "vacuum pipe"), and the adsorbent plays an important role in obtaining and maintaining a vacuum degree of the sandwich at a low temperature. The vacuum life of the interlayer depends to a large extent on the nature of the adsorbent, the loading and whether its action is fully exerted.

The traditional manufacturing process of the vacuum pipeline is that firstly, the temperature of more than 600 ℃ is used for activating the adsorbent to prepare the adsorbent bag, the adsorbent bag is compounded on the inner pipe, then the inner pipe and the outer pipe are compounded, the leakage detection is carried out on the vacuum pipeline after the compounding, and then the heating and vacuumizing work is carried out until the requirement of the vacuum degree is met. In the vacuum pipeline obtained by the process, the water absorbed by the adsorbent in the interlayer in the preparation process is difficult to desorb completely, so that the adsorption performance is reduced, and the service life of the vacuum degree is short.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a vacuum pipeline and a preparation process thereof, the vacuum pipeline fills an adsorbent in a cylinder with a plurality of through holes, the cylinder and an inner pipe are sealed by spot welding, the through holes are sealed by thermoplastic materials, the adsorbent is prevented from adsorbing moisture, the vacuum pipeline is heated after vacuumizing is finished, the thermoplastic materials are melted, the through holes are all opened, the adsorbent starts to adsorb, and the vacuum degree is maintained. In the preparation process of the vacuum pipeline, the adsorbent absorbs less moisture and does not need high-temperature desorption, so that the adsorbent can fully exert the function of the adsorbent, the vacuum degree of the interlayer at low temperature is maintained, and the service life of the vacuum degree is prolonged.

The technical scheme adopted by the invention is as follows:

a vacuum conduit, comprising:

an outer tube;

the inner pipe is arranged inside the outer pipe and is coaxial with the outer pipe, and an interlayer space is formed between the outer side wall of the inner pipe and the inner side wall of the outer pipe;

the cylinder is positioned in the interlayer space, is sleeved on the inner pipe, and is connected with the inner pipe at two ends to form sealing; a filling space is formed between the inner side wall of the cylinder and the outer side wall of the inner pipe;

the adsorbent bag is fixedly arranged in the filling space;

the cylinder is provided with a plurality of through holes, and the through holes are plugged by thermoplastic materials so that the cylinder and the outer side wall of the inner tube form sealing; and vacuumizing the interlayer space, heating to melt the thermoplastic material, opening the through holes completely, adsorbing the interlayer space by the adsorbent bag, and maintaining the vacuum degree of the interlayer space.

In the vacuum pipeline, the axial length of the cylinder is 20 to 200mm.

In the vacuum pipeline of the application, the aperture of the through hole is smaller than the diameter of the adsorbent particles in the adsorbent bag.

Based on the same inventive concept, the invention also discloses a preparation process of the vacuum pipeline, and particularly,

the preparation process of the vacuum pipeline comprises the following steps:

s1, selecting a plate according to the interlayer space of the vacuum pipeline and the required vacuum degree of the vacuum pipeline, and forming a plurality of through holes in the plate;

s2, selecting an inner tube, rolling and welding the plate into a cylinder, and sleeving the inner tube; one end of the cylinder is connected with the inner tube in a spot welding mode to form a seal;

s3, activating the adsorbent, and loading the adsorbent into the cylinder from the other end of the cylinder to compound the adsorbent with the inner side wall of the cylinder and the outer side wall of the inner tube to form an adsorbent bag; the other end of the cylinder is connected with the inner tube in a spot welding mode to form sealing; heating and melting the thermoplastic material, and pouring the thermoplastic material on the through hole of the cylinder to completely seal the cylinder and the inner tube;

s4, compounding the inner pipe and the outer pipe to form a vacuum pipeline, and detecting the leakage of the interlayer space of the vacuum pipeline;

s5, after leak detection, the vacuum pipeline enters a furnace and is vacuumized; and pumping the interlayer space to vacuum, heating to completely melt the thermoplastic material, opening the through holes, adsorbing the interlayer space by the adsorbent, and maintaining the vacuum degree of the interlayer space.

In the process for preparing the vacuum pipeline disclosed by the application, the adsorbent is a 5A molecular sieve and palladium oxide.

In the preparation process of the vacuum pipeline disclosed by the application, the packing density of the 5A molecular sieve is not less than 0.65g/mL.

In the preparation process of the vacuum pipeline disclosed by the application, the loading amount of the palladium oxide is 1-5 g.

In the preparation process of the vacuum pipeline disclosed by the application, the melting point of the thermoplastic material is 80-90 ℃.

In the preparation process of the vacuum pipeline disclosed by the application, the plate is made of austenitic stainless steel, and the thickness of the plate is 0.3-0.5 mm.

In the preparation process of the vacuum pipeline disclosed by the application, in the step S4, before the inner pipe and the outer pipe are compounded, the outer side surfaces of the inner pipe and the cylinder are wrapped with 16-18 layers of heat insulating materials.

Compared with the prior art, the invention has the beneficial effects that:

the utility model provides a vacuum pipeline packs the adsorbent in the drum that has a plurality of through-holes, and is sealed with drum and inner tube spot welding again, and the through-hole passes through thermoplastic material and seals, seals the adsorbent in filling the space, avoids in vacuum pipeline's preparation process, and moisture and gas in the adsorbent absorption intermediate layer space heat after vacuum pipeline takes out to the vacuum, make thermoplastic material melt, and the through-hole is all opened, and the adsorbent begins to adsorb, maintains the vacuum in intermediate layer space. In the preparation process of the vacuum pipeline, the adsorbent absorbs less water and does not need high-temperature desorption, so that the adsorbent can fully exert the function, the vacuum degree of the interlayer at low temperature is maintained, and the service life of the vacuum degree is prolonged.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic view of a vacuum line;

FIG. 2 is a flow chart of a process for preparing a vacuum tube.

Reference numerals:

1. an outer tube; 2. an inner tube; 3. an interlayer space; 4. a cylinder; 5. a filling space; 6. an adsorbent pack; 7. and a through hole.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not limiting of the application. It should be further noted that, for the convenience of description, only some of the structures related to the present application are shown in the drawings, not all of the structures. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The terms "comprising" and "having," and any variations thereof, in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein may be combined with other embodiments.

Referring to fig. 1~2, an embodiment of the present application provides a vacuum pipeline and a preparation process thereof, and mainly aims to solve the problems that water adsorbed by an adsorbent in an interlayer of an existing vacuum pipeline is difficult to desorb completely in a preparation process, so that adsorption performance is reduced and a vacuum degree life is short.

The application discloses a vacuum pipe includes:

an outer tube 1;

the inner tube 2 is arranged inside the outer tube 1 and is coaxial with the outer tube 1, and an interlayer space 3 is formed between the outer side wall of the inner tube 2 and the inner side wall of the outer tube 1;

the cylinder 4 is positioned in the interlayer space 3, is sleeved on the inner pipe 2, and is connected with the inner pipe 2 at two ends to form sealing; a filling space 5 is formed between the inner side wall of the cylinder 4 and the outer side wall of the inner tube 2;

an adsorbent pack 6 fixedly disposed in the filling space 5;

wherein, a plurality of through holes 7 are arranged on the cylinder 4, and the through holes 7 are plugged by thermoplastic materials, so that the cylinder 4 and the outer side wall of the inner tube 2 form a seal; the interlayer space 3 is vacuumized and then heated, so that the thermoplastic material can be melted, the through holes 7 are all opened, the adsorbent bag 6 adsorbs the interlayer space 3, and the vacuum degree of the interlayer space 3 is maintained.

Activated carbon and 5A molecular sieve are two common adsorbents in the vacuum pipeline interlayer space 3, and the 5A molecular sieve is taken as an example for illustration. The traditional manufacturing process of the vacuum pipeline is that the 5A molecular sieve is activated at the temperature of more than 600 ℃ to prepare the adsorbent bag 6, the adsorbent bag is compounded on the inner pipe 2, then the inner pipe and the outer pipe are compounded, the leakage detection is carried out on the vacuum pipeline after compounding, and then the heating and vacuumizing work is carried out until the requirement of the vacuum degree is met.

The traditional manufacturing process of the vacuum pipeline can cause the adsorbent to lose partial activity, and the specific reasons are as follows:

first, the 5A molecular sieve is greatly affected by the environment before and after activation, especially the air humidity, and the longer the exposure time in the air, the more moisture the 5A molecular sieve adsorbs. Because under atmospheric conditions, the 5A molecular sieve pairs

，

The adsorption amount of the main component of air such as Ar is small and the like to

And

has a large adsorption amount, but

The content in the atmosphere is very small, so that water is mainly adsorbed, and the 5A molecular sieve still has water absorption capacity under the extremely low water vapor partial pressure, so that the water adsorbed in the atmosphere by the 5A molecular sieve is difficult to be desorbed completely in the vacuumizing and degassing process of the interlayer space 3. Secondly, after the 5A molecular sieve is quickly compounded with the inner pipe 2, the molecular sieve which is already subjected to the high Wen Huohua begins to play a role, a large amount of air still exists in the interlayer space 3 between the inner pipe and the outer pipe at this time, the time for waiting before the vacuum pipe enters the furnace for vacuumizing (the vacuum pipe needs to enter the furnace in batches) is changed relative to the number of the vacuum pipe, and during the time, the 5A molecular sieve bag continues to absorb the moisture in the interlayer space 3. Finally, the vacuum pipeline is heated in a furnace, and the vacuum pumping is started, and the processes of firstly pumping to common vacuum, continuously pumping to high vacuum and then heating to 100 ℃ and above are carried out, and the 5A molecular sieve is wrapped and absorbed

，

After waiting for the gas, the performance is degraded. In practice, it is often difficult to effectively heat the 5A molecular sieve in the interlayer space 3 to above 100 ℃, thereby limiting the thoroughness of dehydration of the 5A molecular sieve in the interlayer space 3 during the vacuum degassing process.

The application of the vacuum pipeline fills the adsorbent in the cylinder 4 with a plurality of through holes 7, and is sealed with the cylinder 4 and the inner tube 2 again, and the through hole 7 is sealed through thermoplastic material, seals the adsorbent in the filling space 5, avoids the adsorbent to adsorb moisture and gas in the interlayer space 3, heats after the vacuum pipeline vacuumization is finished, makes thermoplastic material melt, and the through hole 7 is all opened, and the adsorbent begins to adsorb, maintains the vacuum degree of the interlayer space 3, improves the vacuum degree life-span.

In one embodiment, the two ends of the cylinder 4 are spot welded to the inner tube 2 to ensure that the cylinder 4 is sealed to the inner tube 2 to prevent the adsorbent in the filling space 5 from adsorbing moisture and gas in the interlayer space 3.

In one embodiment, the axial length of the cylinder 4 is 20 to 200mm, and the appropriate length of the cylinder 4 can be selected according to the change of the caliber of the vacuum pipeline.

In one embodiment, the aperture of the through holes 7 is smaller than the diameter of the sorbent particles in the sorbent cartridge 6, preventing the sorbent particles from falling out of the cylinder 4 through the through holes 7.

The above-mentioned embodiments describe the structure of the vacuum pipe in more detail, and the following embodiments will attempt to briefly describe the method for manufacturing the vacuum pipe, that is, the process for manufacturing the vacuum pipe, including the following steps:

s1, selecting a plate according to an interlayer space 3 of a vacuum pipeline and the required vacuum degree of the vacuum pipeline, and forming a plurality of through holes 7 in the plate;

s2, selecting an inner tube 2, rolling and welding a plate into a cylinder 4, and sleeving the inner tube 2; one end of the cylinder 4 is connected with the inner tube 2 in a spot welding mode to form a seal;

s3, activating the adsorbent, and loading the adsorbent into the cylinder 4 from the other end of the cylinder 4 to compound the adsorbent with the inner side wall of the cylinder 4 and the outer side wall of the inner tube 2 to form an adsorbent bag 6; the other end of the cylinder 4 is connected with the inner tube 2 in a spot welding mode to form sealing; heating and melting the thermoplastic material, and pouring the thermoplastic material on the through hole 7 of the cylinder 4 to completely seal the cylinder 4 and the inner tube 2;

s4, compounding the inner pipe 2 and the outer pipe 1 to form a vacuum pipeline, and detecting the leakage of the interlayer space 3 of the vacuum pipeline;

s5, after leak detection, the vacuum pipeline enters a furnace and is vacuumized; and vacuumizing the interlayer space 3, heating to completely melt the thermoplastic material, opening all the through holes 7, and adsorbing the interlayer space 3 by the adsorbent to maintain the vacuum degree of the interlayer space 3.

In one embodiment, the adsorbent is 5A molecular sieve and palladium oxide. In case of air leakage (

，

Ar) and material outgassing (mainly

) Among the two factors, the ratio of the total weight of the rubber,

the hydrogen absorbing agent, namely palladium oxide, is added into the adsorbent for pairing the hydrogen and the hydrogen, namely the palladium oxide, with the consideration that all the conventional adsorbents cannot absorb hydrogen (the adsorption capacity is extremely low) at the temperature of liquid oxygen and liquid nitrogen

Adsorption was carried out and the palladium oxide was not associated with 5A molecular sieve.

Specifically, the packing density of the 5A molecular sieve is not less than 0.65g/mL.

Specifically, the loading of palladium oxide is 1 to 5g, that is, the loading of palladium oxide may be 1g, 2g, 3g, 4g, 5g, or the like, preferably 2g.

The table below shows the amount of adsorbent used in the vacuum line.

In one specific implementation scenario, a 6 meter DN50 vacuum pipe is taken as an example: the spherical 5A type molecular sieve has a diameter of 3.0-3.3mm and a volume of 85 mm ³ The amount of molecular sieve is 80 × 6=480g, the bulk density is more than or equal to 0.65g/mL, the volume is 739 mL, and if the outer diameter of the cylinder is 580mm and the outer diameter of the inner pipe is 570mm, the length of the cylinder is 21mm.

In one embodiment, the melting point of the thermoplastic material should not be too low, preferably within the range of 80 to 90 ℃, so that the vacuum pipeline can be completely melted when heated to 100 ℃ or above, and the openings are completely opened. The material for plugging the through-hole 7 in the present invention may be a material having plasticity such as wax.

In one embodiment, the plate is made of austenitic stainless steel, the thickness of the plate is 0.3-0.5 mm, and the plate is convenient to machine.

In one embodiment, in step S4, before the inner pipe 2 and the outer pipe 1 are combined, 16 to 18 layers of heat insulating material are wrapped on the outer surfaces of the inner pipe 2 and the cylinder 4. The thermal insulation material serves to insulate thermal radiation. It should be noted that the thermal insulation material does not affect the function of the adsorbent, and the vacuum loss of the vacuum pipeline is shown in the stage of five to ten years of use, and the adsorbent mainly absorbs hydrogen dissipated by the inner pipe material in the early stage.

According to the preparation process of the vacuum pipeline, a proper plate is selected according to the interlayer space 3 of the vacuum pipeline and the required vacuum degree of the vacuum pipeline, a plurality of through holes 7 are formed in the plate, the plate is coiled into the cylinder 4 to be sleeved on the inner pipe 2, one end of the cylinder 4 is plugged first, then the activated adsorbent is filled, the other end of the cylinder is plugged, then the through holes 7 in the plate are all plugged by the thermoplastic material, a large amount of water is prevented from being adsorbed by the adsorbent through the through holes 7, after the thermoplastic material is completely solidified, the inner pipe 2 is made into the vacuum pipeline meeting the requirements, the vacuum pipeline is vacuumized in a furnace, the thermoplastic material is not melted in the process of pumping to the common vacuum, the gas and the water in the vacuum pipeline cannot be adsorbed, the temperature is heated to 100 ℃ or above, the thermoplastic material is completely melted, all open holes are opened, the adsorbent starts to adsorb, the vacuum degree is maintained, and the service life of the vacuum degree is prolonged. In the preparation process of the vacuum pipeline, the adsorbent absorbs less water and does not need high-temperature desorption, so that the adsorbent can fully exert the function, the vacuum degree of the interlayer at low temperature is maintained, and the service life of the vacuum degree is prolonged.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vacuum conduit, comprising:

an outer tube;

the adsorbent bag is fixedly arranged in the filling space;

2. The vacuum pipe according to claim 1, wherein the cylinder has an axial length of 20 to 200mm.

3. The vacuum conduit according to claim 1, wherein the apertures of the through holes are smaller than the diameter of the adsorbent particles in the adsorbent bag.

4. The preparation process of the vacuum pipeline is characterized by comprising the following steps of:

s2, selecting an inner tube, rolling and welding the plate into a cylinder, and sleeving the cylinder on the inner tube; one end of the cylinder is connected with the inner tube in a spot welding mode to form a seal;

5. The process for preparing a vacuum tube according to claim 4, wherein the adsorbent is 5A molecular sieve and palladium oxide.

6. The process for preparing a vacuum tube according to claim 5, wherein the packing density of the 5A molecular sieve is not less than 0.65g/mL.

7. The manufacturing process of the vacuum pipeline as claimed in claim 5, wherein the loading amount of the palladium oxide is 1 to 5g.

8. The manufacturing process of the vacuum pipeline as claimed in claim 4, wherein the melting point of the thermoplastic material is 80-90 ℃.

9. The manufacturing process of the vacuum pipeline as claimed in claim 4, wherein the plate is made of austenitic stainless steel and has a thickness of 0.3 to 0.5mm.

10. The manufacturing process of the vacuum pipeline according to claim 4, wherein in the step S4, before the inner pipe and the outer pipe are compounded, the outer side surfaces of the inner pipe and the cylinder are wrapped with 16-18 layers of heat insulation materials.