Full-automatic steel cylinder passivation method and system

Abstract

The invention relates to the technical field of steel cylinder passivation, in particular to a full-automatic steel cylinder passivation method and system.The method comprises the steps that a gradient passivation and high-purity fluorine passivation combined mode is adopted, inert gas and fluorine gas pipeline valve switches are interlocked with system pressure, nitrogen partial pressure and fluorine partial pressure which are filled into a system are controlled, and the pressure of the system is controlled; therefore, gradient passivation of passivation mixed gases with different concentrations is realized. In the passivation process, evacuation, replacement and purging of the system are repeatedly carried out for multiple times, so that the gas purity in the fluorination process is ensured. The steel cylinder is passivated in a gradient passivation and high-purity fluorine gas passivation mode, passivation mixed gas with gradient concentration and high-purity fluorine gas react with the inner wall of the steel cylinder to form a layer of firm passivation film, and therefore effective passivation of the steel cylinder is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of steel cylinder passivation, and in particular to a fully automated steel cylinder passivation method and system. Background Art

[0002] The concentration of high-purity specialty gases can reach over 99.999%, and the impurity content is required to be extremely low. High-purity specialty gases are generally stored in steel cylinders. In industry, steel cylinders are often passivated in advance to form a passivation film to prevent the surface of the cylinder from reacting with the specialty gas and bringing in impurities, thereby affecting the purity and properties of the stored gas. Many cylinder passivations use the method of heating with reactive gases, which increases the complexity of the cylinder passivation system and makes the operation complicated.

[0003] At present, the automation level of cylinder passivation technology is not high, and the manual operation is cumbersome. It is difficult to passivate multiple cylinders at the same time. At the same time, the labor intensity is high and the cylinder passivation efficiency is low. Therefore, it is necessary to design a cylinder passivation system with high automation level, safety and reliability, including pipelines, valves, vacuum generators and other devices and corresponding automatic control systems. Summary of the invention

[0004] Based on this, the present invention proposes a fully automated passivation method and system for steel cylinders, establishes a fully automated passivation system for steel cylinders, and realizes fully automated passivation operation of multiple steel cylinders.

[0005] According to a first aspect of the present invention, a method for passivating a steel cylinder is provided, comprising: combining gradient passivation with high-purity fluorine gas passivation, interlocking the inert gas and fluorine gas pipeline valve switches with the system pressure, controlling the nitrogen partial pressure and the fluorine gas partial pressure filled into the system, thereby achieving gradient passivation of passivation mixed gases of different concentrations;

[0006] During the passivation process, the system is evacuated, replaced and purged repeatedly to ensure the gas purity of the fluorination process.

[0007] According to an embodiment of the present invention, the following steps are included:

[0008] Before connecting the new cylinder to the cylinder passivation system, conduct leak detection and evacuation replacement;

[0009] The new cylinder is connected to the system for evacuation and replacement, and the environment in the system is replaced with a mixed gas including He, F2, and N2;

[0010] He gas is injected into the system until the pressure in the system is displayed as 500 kPa;

[0011] Filling the steel cylinder with a fluorine-nitrogen mixed gas, and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner;

[0012] The method of increasing the fluorine gas content in a gradient manner includes: increasing the fluorine gas content in the fluorine-nitrogen mixed gas for multiple times so that the fluorine gas content is 10% to 50% of the total mass of the fluorine-nitrogen mixed gas;

[0013] After the steel cylinder is evacuated, fluorine gas is filled into the steel cylinder and maintained for 24 hours;

[0014] After the passivated steel cylinder is purged with nitrogen, the steel cylinder is disassembled.

[0015] According to an embodiment of the present invention, the step of filling the steel cylinder with a fluorine-nitrogen mixed gas and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner includes:

[0016] Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 10% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 to 3 hours;

[0017] Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 21% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 hours to 3 hours;

[0018] Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 30% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 to 3 hours;

[0019] The steel cylinder is filled with a fluorine-nitrogen mixed gas, wherein the fluorine gas content is 50% of the total mass of the fluorine-nitrogen mixed gas, and maintained for 2 to 3 hours.

[0020] According to an embodiment of the present invention, the leak detection and evacuation replacement before connecting the new cylinder to the cylinder passivation system includes:

[0021] Before installing the cylinder, first conduct positive pressure and negative pressure to maintain the side leakage of the system;

[0022] Inert gas is filled into the steel cylinder, and then the system is evacuated, replaced and purged by combining venturi vacuuming and vacuum pump vacuuming;

[0023] After the replacement purge is completed, observe whether the leak test is qualified.

[0024] According to an embodiment of the present invention, the inert gas is high-purity He or high-purity N2.

[0025] According to an embodiment of the present invention, the absolute pressure of the positive pressure maintaining pressure is ≤600kPa; the absolute pressure of the negative pressure maintaining pressure is ≤7kPa.

[0026] According to an embodiment of the present invention, the step of filling the steel cylinder with an inert gas and then performing an evacuation, replacement and purging operation on the system by a combination of venturi vacuuming and vacuum pump vacuuming includes:

[0027] First, use Venturi to evacuate the air, and the N2 pressure next to the Venturi tube is 100kPa~200kPa;

[0028] When the Venturi is evacuated to a system pressure of -80kPa to -60kPa, use a vacuum pump to evacuate the system, and the final absolute pressure is between 0kPa and 7kPa.

[0029] According to a second aspect of the present invention, there is provided a fully automated steel cylinder passivation system used in the above-mentioned steel cylinder passivation method, comprising:

[0030] A main pipe is provided with a pressure sensor, and the pressure sensor is used to detect the air pressure in the passivation system;

[0031] A steel cylinder installed on the main pipe of the passivation system;

[0032] A first nitrogen source is connected to the main pipeline through a first pipeline, and a vacuum generator and a first valve group are arranged on the first pipeline;

[0033] a vacuum pump connected to the main pipeline via a second pipeline, wherein a second valve group is provided on the second pipeline;

[0034] an inert gas source connected to the main pipeline via a third pipeline, wherein a third valve group is provided on the third pipeline;

[0035] A second nitrogen source is connected to the main pipeline through a fourth pipeline, and a fourth valve group is provided on the fourth pipeline;

[0036] A fluorine source is connected to the main pipeline via a fifth pipeline, and a fifth valve group is provided on the fifth pipeline;

[0037] A venturi vacuum tube connected to the vacuum generator of the first pipeline;

[0038] Among them, the first valve group of the first nitrogen source, the fourth valve group of the second nitrogen source and the fifth valve group of the fluorine source are interlocked with the pressure sensor of the passivation system to control the nitrogen partial pressure and the fluorine partial pressure filled into the system.

[0039] It can be seen from the above technical scheme that the fully automated cylinder passivation method and system provided by the present invention have the following beneficial effects:

[0040] (1) The present invention establishes a fully automated passivation system for steel cylinders by organically combining valves, pipelines, vacuum generators, venturi vacuum tubes, vacuum pumps and other devices as well as corresponding automatic control systems, thereby realizing fully automated passivation operations for multiple steel cylinders.

[0041] (2) The steel cylinder is passivated by gradient passivation and high-purity fluorine gas passivation. The gradient concentration passivation mixed gas and high-purity fluorine gas react with the inner wall of the steel cylinder to form a strong passivation film, thereby achieving effective passivation of the steel cylinder.

[0042] (3) The present invention adopts fully automated control, which greatly reduces the labor intensity of the staff, increases the safety of system operation, improves the safety of the staff, increases the speed of cylinder passivation operation, and greatly improves production efficiency.

[0043] (4) The present invention adopts the method of first venturi vacuuming and then vacuum pump vacuuming to perform the vacuum replacement operation, which solves the problem that the vacuum pump cannot directly draw positive pressure. At the same time, the Venturi tube has a simple structure and can achieve the vacuum effect with the vacuum generator, reducing system energy consumption and simplifying system equipment.

[0044] (5) The system of the present invention adopts a pressure reducing valve to ensure that the inlet gas pressure of the cylinder is stable and easy to control; a check valve is adopted to ensure that the system will not have gas backflow and pollute the pipeline, gas source, etc., thereby increasing the safety and ease of operation of the system; while the micro-leakage valve controls the gas flow, the removal of the cylinder under a slightly positive pressure condition also ensures that the pipeline system is not polluted by air. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a diagram of the fully automated passivation operating system for cylinders.

[0046] Reference numerals:

[0047] Pneumatic diaphragm valve three-1, pneumatic diaphragm valve five-2, pneumatic diaphragm valve one-3, pneumatic diaphragm valve four-4, pneumatic diaphragm valve two-5, pneumatic diaphragm valve six-6, pneumatic diaphragm valve eight-7, pneumatic diaphragm valve seven-8, gasket filter two-9, gasket filter one-10, gasket filter three-11, gasket filter four-12, gasket filter five-13, manual diaphragm valve one-14, manual diaphragm valve two-15, manual diaphragm valve three-16, the first manual diaphragm valve-17, the second manual diaphragm valve-18, The third manual diaphragm valve-19, the fourth manual diaphragm valve-20, the pneumatic micro-leakage valve one-21, the pneumatic micro-leakage valve two-22, the check valve one-23, the check valve two-24, the check valve three-25, the vacuum generator-26, the pressure reducing valve one-27, the pressure reducing valve two-28, the pressure sensor two-29, the pressure sensor three-30, the first pressure sensor-31, the pressure gauge two-32, the pressure gauge three-33, the first pressure gauge-34, the first steel cylinder-35, the second steel cylinder-36, the third steel cylinder-37, the fourth steel cylinder-38. DETAILED DESCRIPTION

[0048] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0049] According to a first aspect of the present invention, a method for passivating a steel cylinder is provided, comprising: combining gradient passivation with high-purity fluorine gas passivation, interlocking the inert gas and fluorine gas pipeline valve switches with the system pressure, controlling the nitrogen partial pressure and the fluorine gas partial pressure filled into the system, thereby achieving gradient passivation of passivation mixed gases of different concentrations;

[0050] During the passivation process, the system is evacuated, replaced and purged repeatedly to ensure the gas purity of the fluorination process.

[0051] According to an embodiment of the present invention, the following steps are included:

[0052] S1: Before connecting the new cylinder to the cylinder passivation system, perform leak detection and evacuation replacement;

[0053] S2: A new cylinder is connected to the system for evacuation and replacement, and the environment in the system is replaced with a mixed gas including He, F2, and N2;

[0054] S3: Inject He gas into the system until the pressure in the system shows 500 kPa;

[0055] S4: Filling the steel cylinder with a fluorine-nitrogen mixed gas, and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner;

[0056] The method of increasing the fluorine gas content in a gradient manner includes: increasing the fluorine gas content in the fluorine-nitrogen mixed gas for multiple times so that the fluorine gas content is 10% to 50% of the total mass of the fluorine-nitrogen mixed gas;

[0057] S5: After the steel cylinder is evacuated, fluorine gas is filled into the steel cylinder and maintained for 24 hours;

[0058] S6: After purging the passivated cylinder with nitrogen, disassemble the cylinder.

[0059] According to an embodiment of the present invention, in S4, a fluorine-nitrogen mixed gas is filled into the steel cylinder, and the steel cylinder is passivated by increasing the fluorine gas content in a gradient manner, including:

[0060] Fill the cylinder with a fluorine-nitrogen mixed gas, where the fluorine content is 10% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2h to 3h;

[0061] Fill the cylinder with a fluorine-nitrogen mixed gas, where the fluorine content is 21% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2h to 3h;

[0062] Fill the cylinder with a fluorine-nitrogen mixed gas, where the fluorine content is 30% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2h to 3h;

[0063] Fill the cylinder with a fluorine-nitrogen mixed gas, in which the fluorine content is 50% of the total mass of the fluorine-nitrogen mixed gas, and maintain it for 2h to 3h.

[0064] According to an embodiment of the present invention, in S1, before connecting a new cylinder to the cylinder passivation system, leak detection and evacuation replacement are performed, including:

[0065] Before installing the cylinder, first conduct positive and negative pressure maintenance on the system to check for side leakage;

[0066] Fill the cylinder with inert gas, and then use a combination of venturi vacuuming and vacuum pump vacuuming to evacuate, displace and purge the system;

[0067] After the replacement purge is completed, observe whether the leak test is qualified.

[0068] According to an embodiment of the present invention, in S1, the inert gas is high-purity He or high-purity N2.

[0069] According to an embodiment of the present invention, in S1, the absolute pressure of the positive pressure maintaining step is ≤600kPa; the absolute pressure of the negative pressure maintaining step is ≤7kPa.

[0070] According to an embodiment of the present invention, in S1, the inert gas is selected to be high-purity He, the positive pressure maintaining pressure is 500 kPa (gauge pressure), the negative pressure maintaining pressure is 7 kPa (absolute pressure), the Venturi is evacuated to -60 kPa (gauge pressure), and the control conditions of the vacuum pump evacuating to 7 kPa (absolute pressure) are more preferred.

[0071] According to an embodiment of the present invention, in S1, an inert gas is filled into the cylinder, and then the system is evacuated, replaced and purged by a combination of venturi vacuuming and vacuum pump vacuuming, including:

[0072] First, use Venturi to evacuate the air, and the N2 pressure next to the Venturi tube is 100kPa~200kPa;

[0073] When the Venturi is evacuated to a system pressure of -80kPa to -60kPa, use a vacuum pump to evacuate the system, and the final absolute pressure is between 0kPa and 7kPa.

[0074] According to an embodiment of the present invention, it is more preferred that the Venturi tube is equipped with N2 of 200 kPa (gauge pressure).

[0075] According to an embodiment of the present invention, in S5, after the passivation is completed, the pressure of the system positive pressure maintenance operation is ≤600 kPa (absolute pressure), and the negative pressure maintenance pressure is ≤7 kPa (absolute pressure).

[0076] According to an embodiment of the present invention, in S6, after the side leakage is qualified, the cylinder is removed while maintaining a slight positive pressure of the He pipeline, i.e., 0.1-0.5 kPa.

[0077] According to an embodiment of the present invention, in S4, the N2 partial pressure is controlled to be 90 kPa (absolute pressure), the F2 gradient partial pressure is controlled to be 10 kPa, 25 kPa, 40 kPa, and 90 kPa, and the passivation holding time is 3 h, which is more preferred.

[0078] According to an embodiment of the present invention, in S5, when the system is passivated with high-purity fluorine gas, the system Venturi is evacuated to -80 kPa (gauge pressure) and the fluorine gas is filled with a partial pressure of 200 kPa (absolute pressure), which is a more preferred condition.

[0079] According to an embodiment of the present invention, in S6, after the passivation is completed, the positive pressure maintaining operation pressure is 500 kPa (gauge pressure), and during the negative pressure maintaining operation, the system is venturi evacuated to -80 kPa (gauge pressure), and the condition of the vacuum tube pump evacuating the pressure to 0.1 kPa is more preferred.

[0080] According to an embodiment of the present invention, in S6, after the side leakage is qualified, it is more preferable to maintain a slight positive pressure condition of 0.5 kPa in the He pipeline.

[0081] According to a second aspect of the present invention, Figure 1 As shown, a fully automated steel cylinder passivation system used in the above-mentioned steel cylinder passivation method is provided, comprising:

[0082] A main pipe is provided with a pressure sensor, and the pressure sensor is used to detect the air pressure in the passivation system;

[0083] A steel cylinder installed on the main pipe of the passivation system;

[0084] A first nitrogen source is connected to the main pipeline through a first pipeline, and a vacuum generator and a first valve group are arranged on the first pipeline;

[0085] a vacuum pump connected to the main pipeline via a second pipeline, wherein a second valve group is provided on the second pipeline;

[0086] an inert gas source connected to the main pipeline via a third pipeline, wherein a third valve group is provided on the third pipeline;

[0087] A second nitrogen source is connected to the main pipeline through a fourth pipeline, and a fourth valve group is provided on the fourth pipeline;

[0088] A fluorine source is connected to the main pipeline via a fifth pipeline, and a fifth valve group is provided on the fifth pipeline;

[0089] A venturi vacuum tube connected to the vacuum generator of the first pipeline;

[0090] Among them, the first valve group of the first nitrogen source, the fourth valve group of the second nitrogen source and the fifth valve group of the fluorine source are interlocked with the pressure sensor of the passivation system to control the nitrogen partial pressure and the fluorine partial pressure filled into the system.

[0091] According to an embodiment of the present invention, four steel cylinders can be provided and installed on the main pipe of the passivation system. A manual diaphragm valve can be installed between the steel cylinder and the main pipe, which may include: a first steel cylinder 35 installed on the main pipe through a first manual diaphragm valve 17, a second steel cylinder 36 installed on the main pipe through a second manual diaphragm valve 18, a third steel cylinder 37 installed on the main pipe through a third manual diaphragm valve 19, and a fourth steel cylinder 38 installed on the main pipe through a fourth manual diaphragm valve 20.

[0092] According to the embodiment of the present invention, a first pressure sensor 31 and a first pressure gauge 34 are installed in the main pipeline.

[0093] According to an embodiment of the present invention, the first valve group includes: a pneumatic micro-leakage valve 21, a check valve 23, a vacuum generator 26, a pneumatic diaphragm valve 3, a gasket filter 10 and a pneumatic diaphragm valve 5.

[0094] According to an embodiment of the present invention, the second valve group includes: a pneumatic diaphragm valve three 1, a gasket filter two 9 and a pneumatic diaphragm valve four 4;

[0095] Among them, the gasket filter 3 11, the pneumatic diaphragm valve 5 2 and the second pressure sensor are connected in parallel between the gasket filter 2 9 and the pneumatic diaphragm valve 4 4.

[0096] According to an embodiment of the present invention, the third valve group includes: a manual diaphragm valve 14, a pneumatic micro-leakage valve 22, a check valve 24, and a pneumatic diaphragm valve 66.

[0097] According to an embodiment of the present invention, the fourth valve group includes: a manual diaphragm valve 2 15, a gasket filter 4 12, a pressure gauge 2 32, a pressure reducing valve 1 27, a pressure sensor 2 29, a check valve 3 25, and a pneumatic diaphragm valve 7 8.

[0098] According to an embodiment of the present invention, the fifth valve group includes: a manual diaphragm valve three 16, a gasket filter five 13, a pressure gauge three 33, a pressure reducing valve two 28, a pressure sensor three 30 and a pneumatic diaphragm valve eight 7.

[0099] Through the organic combination of valves, pipelines, vacuum generators, venturi vacuum tubes, vacuum pumps and other devices as well as the corresponding automatic control system, the fully automated passivation operation of multiple cylinders is realized. The gradient passivation is combined with the high-purity fluorine gas passivation. The inert gas and fluorine gas pipeline valve switches are interlocked with the system pressure to control the nitrogen partial pressure and fluorine partial pressure filled into the system, thereby realizing the gradient passivation of the passivation mixed gas of different concentrations. During the passivation process, the system is repeatedly evacuated, replaced and purged to ensure the gas purity of the fluorination process.

[0100] According to an embodiment of the present invention, the pneumatic diaphragm valve below the Venturi vacuum and vacuum pump pipeline is a safety valve, which remains normally open during the entire operation process. The following Venturi vacuum and vacuum pump evacuation pipeline pneumatic diaphragm valve is a pneumatic diaphragm valve above the safety valve.

[0101] Example 1

[0102] S1: Before connecting the new cylinder to the cylinder passivation system, perform leak detection and evacuation replacement; including:

[0103] (1) Positive pressure maintenance: Close the Venturi vacuum and vacuum pump pneumatic diaphragm valves, close the manual diaphragm valves above the He and F2 pipelines, and open the manual diaphragm valves below the He and F2 pipelines.

[0104] The pneumatic diaphragm valve and the manual valve of the N2 pipeline are filled with N2 until P1 and P2 display 500kPa, and the manual diaphragm valve of the N2 pipeline is closed, and the positive pressure is maintained for 30 minutes;

[0105] (2) Negative pressure maintenance: (first venturi evacuation, then vacuum pump evacuation) Open the pneumatic diaphragm valve of the Venturi pipeline and start Venturi vacuum evacuation. When the vacuum gauge P3 = 63 kPa, the pneumatic diaphragm valve of the Venturi pipeline is interlocked and closed. At the same time, the pneumatic diaphragm valve of the vacuum pump pipeline is automatically opened and the vacuum pump evacuation is started. When P3 = 93 kPa, the pneumatic valve is automatically closed and the negative pressure is maintained for 30 minutes.

[0106] (3) Evacuate and replace:

[0107] ① Filling with helium: Open the manual diaphragm valve of the He pipeline, fill the system with He, and when P2=500kPa, close the manual valve.

[0108] ②Open the pneumatic diaphragm valve of the Venturi pipeline and start the Venturi vacuum pumping. When P3=63kPa, the pneumatic diaphragm valve of the Venturi pipeline is interlocked and closed. At the same time, the pneumatic diaphragm valve of the vacuum pump pipeline is automatically opened to start the vacuum pump vacuum pumping. When P3=100kPa, the pneumatic valve of the vacuum pump pipeline is closed. This completes one purge, which can be repeated to complete multiple purges. (After the purge is completed, the system pressure vacuum is 100kPa)

[0109] ③After the purge is completed, close the pneumatic diaphragm valves of the He, F2, and N2 pipelines

[0110] S2: The new cylinder is connected to the system for evacuation and replacement, and the environment in the system is replaced with a mixed gas including He, F2, and N2; including:

[0111] (1) Connect a new cylinder to the system, open the cylinder manual valve and cylinder pipeline manual valve. Open the manual diaphragm valves of He, F2, and N2 pipelines. (Note: All diaphragm valves are closed at this time)

[0112] (2) The pneumatic diaphragm valve of the Venturi pipeline is automatically opened to start the Venturi vacuum pumping. When P3 = 63 kPa, the pneumatic valve of the Venturi pipeline is interlocked and closed. At the same time, the pneumatic valve of the vacuum pump pipeline is automatically opened to start the vacuum pumping. When P3 = 100 kPa, the pneumatic valve of the vacuum pump pipeline is automatically closed.

[0113] S3: Inject He gas into the system until the pressure in the system is displayed as 500 kPa; including:

[0114] (1) The pneumatic diaphragm valve of the He pipeline is automatically opened and filled with He until P2 displays 500 kPa, and the pneumatic diaphragm valve is automatically closed.

[0115] (2) The pneumatic diaphragm valve of the Venturi pipeline is automatically interlocked to open, and the Venturi vacuum is started. When P3 = 63kPa, the pneumatic valve of the Venturi pipeline is interlocked to close, and the pneumatic valve of the vacuum pump pipeline is automatically opened at the same time, and the vacuum pump starts to evacuate. When P3 = 100kPa, the pneumatic valve of the vacuum pump pipeline is automatically closed. This completes one purge, and can be repeated to complete multiple purges. (After the purge is completed, P3 = 100kPa)

[0116] S4: Filling the steel cylinder with a fluorine-nitrogen mixed gas, and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner;

[0117] The method of increasing the fluorine content in a gradient manner includes: increasing the fluorine content in the fluorine-nitrogen mixed gas for multiple times so that the fluorine content is 10% to 50% of the total mass of the fluorine-nitrogen mixed gas; including:

[0118] (1) 10% fluorine-nitrogen mixed gas: automatically open the pneumatic diaphragm valve of the N2 pipeline, fill the cylinder with 90kPa of N2, and when P2 on the N2 pipeline is 90kPa, the pneumatic diaphragm valve of the N2 pipeline is automatically interlocked and closed. Automatically open the pneumatic diaphragm valve of the F2 pipeline, fill it with 10kPa of F2, and at this time P2 is 10kPa, and the pneumatic diaphragm valve of the F2 pipeline is automatically interlocked and closed, and maintained for 2h~3h.

[0119] (2) 21% fluorine-nitrogen mixed gas: After the holding time is over, the pneumatic diaphragm valve of the F2 pipeline is automatically opened, and F2 is filled until the pressure sensor P2 on the F2 pipeline reaches 25kPa, and the diaphragm valve is automatically interlocked and closed, and maintained for 2h to 3h.

[0120] (3) 30% fluorine-nitrogen mixed gas: After the holding time is over, the pneumatic diaphragm valve of the F2 pipeline is automatically opened, and F2 is filled until the pressure sensor P2 on the F2 pipeline reaches 40 kPa, and the diaphragm valve is automatically interlocked and closed, and maintained for 2h to 3h.

[0121] (4) 50% fluorine-nitrogen mixed gas: After the holding time is over, the pneumatic diaphragm valve of the F2 pipeline is automatically opened, and F2 is filled until the pressure sensor P2 on the F2 pipeline reaches 90 kPa, and the diaphragm valve is automatically interlocked and closed, and maintained for 2h to 3h.

[0122] S5: After the cylinder is evacuated, fill it with fluorine gas and keep it for 24 hours; including:

[0123] High concentration F 2( 95%) passivation: After the gradient passivation is completed, the pneumatic diaphragm valve on the Venturi vacuum pipeline is opened, the Venturi is evacuated to P2 = -80 kPa, and the pneumatic diaphragm valve is automatically closed.

[0124] (6) The pneumatic diaphragm valve on the F2 pipeline is opened by automatic interlocking, and F2 is filled until the pressure sensor P2 on the F2 pipeline reaches 200 kPa, and the pneumatic diaphragm valve is closed by automatic interlocking. Maintain for 24 hours, and the passivation is completed.

[0125] S6: After purging the passivated cylinder with nitrogen, disassemble the cylinder; including:

[0126] (1) Positive pressure maintenance: After the passivation is completed, the pneumatic diaphragm valve of the N2 pipeline is automatically opened, and N2 is filled until the pipeline pressure P2 = 500kPa. The pneumatic diaphragm valve of the N2 pipeline is automatically interlocked and closed, and the pressure is maintained for 30 minutes.

[0127] (2) Evacuate, replace and purge:

[0128] ① Vacuuming: Automatically open the pneumatic diaphragm valve of the Venturi pipeline to start Venturi vacuuming. When P2 = -80kPa, interlock and close the pneumatic diaphragm valve below the Venturi pipeline. At the same time, open the pneumatic valve of the vacuum pump pipeline to start vacuum pumping. When P3 = 100kPa, close the pneumatic valve of the vacuum pump pipeline.

[0129] ② Filling with nitrogen: automatically open the pneumatic diaphragm valve of the N2 pipeline, fill with N2, until P2 displays 500kPa, automatically close the pneumatic diaphragm valve, and evacuate according to step ①. This completes one purge, and repeats to complete multiple purges. (After the purge is completed, P3 = 100kPa)

[0130] (3) Negative pressure maintenance: After purging is completed, close all pipeline pneumatic diaphragm valves and maintain for 30 minutes to perform negative pressure maintenance to detect leaks.

[0131] After the negative pressure leak test is qualified, open the manual valve of the cylinder pipeline, open the pneumatic valve below the He pipeline and the manual valve of the upper pipeline, and when P2 displays a positive pressure of 500Pa, remove the cylinder. The specific embodiments described above further explain the purpose, technical scheme and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for passivating a steel cylinder, characterized in that: include: The gradient passivation is combined with high-purity fluorine gas passivation. The valve switches of the inert gas and fluorine gas pipelines are interlocked with the system pressure to control the nitrogen partial pressure and fluorine partial pressure of the system, thereby achieving gradient passivation of passivation mixed gases of different concentrations. During the passivation process, the system is evacuated, replaced and purged repeatedly to ensure the gas purity of the fluorination process.

2. The method according to claim 1, characterized in that The steps include: Before connecting the new cylinder to the cylinder passivation system, conduct leak detection and evacuation replacement; The new cylinder is connected to the system for evacuation and replacement, and the environment in the system is replaced with a mixed gas including He, F2, and N2; He gas is injected into the system until the pressure in the system is displayed as 500 kPa; Filling the steel cylinder with a fluorine-nitrogen mixed gas, and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner; The method of increasing the fluorine gas content in a gradient manner includes: increasing the fluorine gas content in the fluorine-nitrogen mixed gas for multiple times so that the fluorine gas content is 10% to 50% of the total mass of the fluorine-nitrogen mixed gas; After the steel cylinder is evacuated, fluorine gas is filled into the steel cylinder and maintained for 24 hours; After the passivated steel cylinder is purged with nitrogen, the steel cylinder is disassembled.

3. The method according to claim 2, characterized in that The method of filling the steel cylinder with a fluorine-nitrogen mixed gas and passivating the steel cylinder by increasing the fluorine gas content in a gradient manner includes: Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 10% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 to 3 hours; Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 21% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 hours to 3 hours; Fill the steel cylinder with a fluorine-nitrogen mixed gas, wherein the fluorine content is 30% of the total mass of the fluorine-nitrogen mixed gas, and keep it for 2 to 3 hours; The steel cylinder is filled with a fluorine-nitrogen mixed gas, wherein the fluorine gas content is 50% of the total mass of the fluorine-nitrogen mixed gas, and maintained for 2 to 3 hours.

4. The method according to claim 2, characterized in that: The leak detection and evacuation replacement before connecting the new cylinder to the cylinder passivation system includes: Before installing the cylinder, first conduct positive pressure and negative pressure to maintain the side leakage of the system; Inert gas is filled into the steel cylinder, and then the system is evacuated, replaced and purged by combining venturi vacuuming and vacuum pump vacuuming; After the replacement purge is completed, observe whether the leak test is qualified.

5. The method according to claim 4, characterized in that The inert gas is high-purity He or high-purity N2.

6. The method according to claim 4, characterized in that The absolute pressure of the positive pressure maintaining step is ≤600kPa; the absolute pressure of the negative pressure maintaining step is ≤7kPa.

7. The method according to claim 4, characterized in that The inert gas is filled into the cylinder, and then the system is evacuated, replaced and purged by a combination of venturi vacuuming and vacuum pump vacuuming, including: First, use Venturi to evacuate the air, and the N2 pressure next to the Venturi tube is 100kPa~200kPa; When the Venturi is evacuated to a system pressure of -80kPa to -60kPa, use a vacuum pump to evacuate the system, and the final absolute pressure is between 0kPa and 7kPa.

8. A fully automated steel cylinder passivation system used in the method for passivating steel cylinders according to any one of claims 1 to 7, characterized in that: include: A main pipe is provided with a pressure sensor, and the pressure sensor is used to detect the air pressure in the passivation system; A steel cylinder installed on the main pipe of the passivation system; a first nitrogen source, connected to the main pipeline through a first pipeline, wherein a vacuum generator and a first valve group are provided on the first pipeline; a vacuum pump connected to the main pipeline via a second pipeline, wherein a second valve group is provided on the second pipeline; an inert gas source connected to the main pipeline via a third pipeline, wherein a third valve group is provided on the third pipeline; A second nitrogen source is connected to the main pipeline through a fourth pipeline, and a fourth valve group is provided on the fourth pipeline; A fluorine source is connected to the main pipeline via a fifth pipeline, and a fifth valve group is provided on the fifth pipeline; A venturi vacuum tube connected to the vacuum generator of the first pipeline; Among them, the first valve group of the first nitrogen source, the fourth valve group of the second nitrogen source and the fifth valve group of the fluorine source are interlocked with the pressure sensor of the passivation system to control the nitrogen partial pressure and the fluorine partial pressure filled into the system.

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