A hydrogen pipeline pigging and launching system and method

Abstract

This invention discloses a safe pigging system and method for hydrogen pipelines. To overcome the problem that excessively high temperatures in some gases may occur after hydrogen pressurization, leading to material performance degradation and safety risks within the pigging system, this invention incorporates the following components into the pipeline pigging circuit: a flow control unit, located in the bypass of the shut-off valve on the large cylinder branch between the upstream hydrogen pipeline and the pigging cylinder, to detect and control the pressurization flow rate; a pressure monitoring unit, located at the blind flange port of the pigging cylinder, to monitor the pressure at the port; and a temperature monitoring unit, distributed along the pigging direction of the pigging cylinder, to monitor the temperature at each location. By identifying the potential for short-term high temperatures during hydrogen pipeline pigging operations and implementing flow control and temperature monitoring, this invention effectively overcomes the problem of localized high gas temperatures during hydrogen filling and pressurization, ensuring the safe implementation of hydrogen pipeline pigging operations.

Description

Technical Field

[0001] This invention relates to the field of hydrogen pipeline transportation, and in particular to a safe pipeline cleaning and pigging system and method for hydrogen pipelines. Background Technology

[0002] Hydrogen, as a key development direction for new energy sources, boasts significant advantages over traditional fossil fuels, including high calorific value, environmentally friendly combustion products, wide availability, and renewability. It is hailed as a clean energy source of the future and will become a new pathway for humanity to address increasingly severe energy and environmental challenges. Hydrogen transportation is a crucial link in hydrogen energy utilization. Employing reliable pipeline transportation to connect hydrogen sources with target users is key to optimizing energy consumption and promoting hydrogen energy utilization.

[0003] Hydrogen pipeline transportation operates similarly to natural gas pipelines, typically requiring functions such as pipeline cleaning, metering, safety shut-off, and dust removal. Regarding the physical characteristics of the medium, hydrogen exhibits a significant anti-coke-Thomson effect compared to natural gas. This means that after pressure regulation and throttling in the pipeline, the medium temperature remains essentially constant, while natural gas experiences a substantial drop. Therefore, conventional natural gas pipelines pay particular attention to pressure regulation during operation, focusing on the temperature drop and low-temperature issues caused by throttling. In contrast, due to the unique anti-coke-Thomson effect of hydrogen, temperature drop caused by pressure regulation and throttling does not need to be considered during hydrogen operation.

[0004] During pipeline cleaning, high-pressure hydrogen needs to be introduced from the main pipeline into the purged atmospheric pressure pigging system to establish a pressure almost equal to that of the downstream pipeline before the pig can be deployed. Due to the unique anti-Jack-Thomson effect of hydrogen, and the gas laws governing conventional gases, this pressurization process is similar to strongly pressurizing the initially introduced low-pressure, room-temperature hydrogen.

[0005] Currently, there are automatic pigging devices for natural gas pipelines. For example, a fully automatic pigging device and its usage method disclosed in Chinese patent literature, CN113333409A, includes a pigging pipe section, a pigging ball valve B, an automatic ball changing mechanism, and a hydraulic system connected in sequence. The pigging pipe section consists of a section of pipe with the same diameter as the gas transmission pipeline. The pigging pipe section has one end connected to the gas transmission pipeline, and the other end of the pigging pipe section is connected to the pigging ball valve B. The pigging pipe section is equipped with a pressure sensor. The hydraulic system includes a hydraulic cylinder. The end of the pigging ball valve B away from the pigging pipe section is connected to the automatic ball changing mechanism, and the end of the automatic ball changing mechanism away from the pigging ball valve B is connected to the hydraulic cylinder. It also includes a PLC controller. The pigging pipe section, the pigging ball valve B, the automatic ball changing mechanism, and the hydraulic system are all connected to the PLC controller via electrical signals.

[0006] However, compared to natural gas, hydrogen, at the same pressure ratio and initial temperature, reaches a much higher temperature after pressurization. Therefore, this could cause some of the gas to overheat, leading to material degradation in pipeline materials and seals within the pigging system, posing a safety risk.

[0007] Currently, there are few public reports on pigging systems specifically designed for hydrogen pipelines, and the unique problems inherent in this operation are easily overlooked during the design phase. Therefore, it is necessary to discuss the safety features of pigging systems for hydrogen pipelines. Summary of the Invention

[0008] This invention primarily addresses the issue that, compared to natural gas, hydrogen, under the same pressure ratio and initial temperature, reaches a much higher temperature after pressurization. This can lead to excessively high temperatures in parts of the gas, causing material degradation in pipeline materials and seals within the pigging system, posing safety risks. The invention provides a safe pigging system and method for hydrogen pipelines. Based on the typical reverse coke-like properties of hydrogen and combined with the adiabatic compression temperature rise law of gases, it identifies potential short-term high-temperature characteristics during hydrogen pipeline pigging operations. By setting up systems such as flow control and temperature monitoring, it effectively overcomes the problem of localized high gas temperatures during the filling and pressurization process of high-pressure hydrogen into the atmospheric-pressure pigging cylinder. This avoids the use of excessively high-grade materials or operational risks to pipeline materials, seals, and pigs, ensuring the safe implementation of hydrogen pipeline pigging operations.

[0009] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0010] A safe pipeline cleaning and launching system for hydrogen pipelines includes a pipeline cleaning circuit. The cleaning and launching cylinder in the pipeline cleaning circuit forms a loop with the main hydrogen pipeline, the main cylinder branch, and the main cleaning pipeline. The pipeline cleaning circuit is equipped with:

[0011] The flow control unit is located in the bypass of the shut-off valve on the large cylinder branch between the upstream hydrogen pipeline and the pigging cylinder, and detects and controls the pressurization flow.

[0012] The pressure monitoring unit is installed at the blind flange port of the pigging launcher to monitor the pressure at the port;

[0013] Temperature monitoring units are distributed along the pigging direction of the pigging launcher to monitor the temperature at each location.

[0014] Based on the typical reverse coke-like properties of hydrogen and combined with the temperature rise law of gas adiabatic compression, the solution identifies the short-term high-temperature characteristics that may exist in the pigging operation of hydrogen pipelines. By setting up systems such as flow control and temperature monitoring, it can effectively overcome the problem of local gas high temperature during the filling and pressurization process of high-pressure hydrogen from the trunk line to the atmospheric pressure pigging cylinder, avoid using excessively high-grade materials or causing operational risks to pipes, seals, pigs, etc., and ensure the safe implementation of hydrogen pipeline pigging operations.

[0015] Preferably, the pressure monitoring unit includes a pressure transmitter, which is installed at the port of the pigging tube.

[0016] The pressure transmitter is used to monitor the pressure at the corresponding location in real time, namely the pressure value at the outlet port of the pigging and launching cylinder. The pressure value at this location is used to determine the overall pressure change inside the pigging and launching cylinder, so as to avoid the pressure rising too quickly during internal stamping.

[0017] Preferably, the temperature monitoring unit includes several temperature transmitters; the first temperature transmitter is located at the port of the pigging and launching cylinder; the second temperature transmitter is located at the width change point of the pigging and launching cylinder; and the third temperature transmitter is located at the other end away from the port of the pigging and launching cylinder.

[0018] Temperature transmitters are set along the gas flow direction to detect the local temperature at various locations inside the pigging and launching cylinder in real time, thus avoiding localized high temperatures during stamping.

[0019] Preferably, the flow control unit includes a large cylinder branch regulating valve and a large cylinder branch flow transmitter; the large cylinder branch is located between the pigging launcher and the upstream hydrogen pipeline, and several shut-off valves are installed on the large cylinder branch, with the large cylinder branch regulating valve and the large cylinder branch flow transmitter located on the bypass of the same shut-off valve.

[0020] The large cylinder branch flow transmitter is installed on the bypass of the large cylinder branch shut-off valve to detect the charging flow of the large cylinder branch; the large cylinder branch regulating valve is installed on the bypass of the large cylinder branch shut-off valve, normally closed, and only opened when gas is charged from the large cylinder branch to the pigging cylinder to control the charging flow.

[0021] Preferably, the pipeline cleaning circuit includes a pigging launcher, which comprises a large cylinder and a small cylinder with different diameters; the large cylinder and the small cylinder are connected by a transition pipe.

[0022] Gas is pumped from the large cylinder into the small cylinder to pressurize the low-pressure, room-temperature hydrogen.

[0023] Preferably, one end of the small cylinder is connected to the pigging main line, and the branch line of the large cylinder is located between the upstream hydrogen pipeline and the large cylinder; the hydrogen main line within the station is located between the branch line of the large cylinder and the pigging branch line.

[0024] Preferably, a first shut-off valve and a second shut-off valve for pigging are sequentially installed on the pigging branch; a first shut-off valve for the main hydrogen line is installed on the station's main line; and a first shut-off valve for the main cylinder branch and a second shut-off valve for the main cylinder branch are sequentially installed on the main cylinder branch.

[0025] A method for safe pigging and launching of hydrogen pipelines, employing a safe pigging and launching system for hydrogen pipelines, includes the following steps:

[0026] S1: Initialize the hydrogen pipeline safety pigging system, close the shut-off valves on each branch, and open the shut-off valves on the main hydrogen pipeline and the external transmission pipeline within the station.

[0027] S2: Before planned pigging, perform pig insertion and replacement operations; perform hydrogen filling operation inside the pigging launcher; control the flow rate based on the real-time monitored temperature and pressure values ​​compared with thresholds;

[0028] S3: Hydrogen filling is complete, real-time pigging operation begins; the shut-off valves on the main cylinder branch and the pigging branch are opened; the shut-off valve on the hydrogen main line in the station is closed, the medium is introduced into the pigging launcher, and the pig is launched.

[0029] Preferably, the pig insertion and replacement operation is as follows:

[0030] Open the blind flange of the pigging launcher, place the pig into the small cylinder, and replace the internal air through the replacement pipeline configured in the pigging launcher.

[0031] After the replacement is completed, the pigging tube is kept at normal pressure.

[0032] Preferably, the hydrogen filling operation inside the pigging and launching tube specifically includes:

[0033] Open the first shut-off valve of the main cylinder branch, while keeping the second shut-off valve of the main cylinder branch, the first shut-off valve of the pigging pipeline, and the second shut-off valve of the pigging pipeline closed;

[0034] Open the main cylinder branch regulating valve to fill the high-pressure hydrogen in the station's hydrogen trunk line into the pigging and launching cylinder, and open the cylinder connection shut-off valve.

[0035] Monitor the temperature transmitter. When the temperature exceeds the maximum design operating temperature of the pigging cylinder, immediately close the regulating valve of the main cylinder branch.

[0036] The alternating operation continues until the pressure inside the pigging tube rises to near the main line pressure, indicating that the pressure filling is complete and the pressure in the large and small pigging tubes has reached equilibrium.

[0037] The beneficial effects of this invention are:

[0038] 1. Based on the typical reverse coke properties of hydrogen and combined with the temperature rise law of gas adiabatic compression, the short-term high temperature characteristics that may exist in the pigging operation of hydrogen pipeline were identified. By setting up systems such as flow control and temperature monitoring, the problem of local gas high temperature during the filling and pressurization process of high-pressure hydrogen from the trunk line to the atmospheric pressure pigging cylinder was effectively overcome. This avoids the use of excessively high-grade materials or the operational risks to pipes, seals, pigs, etc., and ensures the safe implementation of the pigging operation of hydrogen pipeline.

[0039] 2. The pressure transmitter is used to monitor the pressure at the corresponding location in real time, that is, the pressure value at the outlet port of the pigging and launching cylinder. The pressure value at this location is used to judge the overall pressure change inside the pigging and launching cylinder, so as to avoid the pressure rising too quickly during internal stamping.

[0040] 3. Temperature transmitters are set along the gas flow direction to detect the local temperature at various locations inside the pigging and launching cylinder in real time, thus avoiding localized high temperatures during stamping. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the connection of the hydrogen pipeline safety cleaning and launching system of the present invention.

[0042] Figure 2 This is a flowchart of the hydrogen pipeline safe cleaning and launching method of the present invention.

[0043] In the diagram: 1. Hydrogen trunk line within the station; 2. First shut-off valve of the trunk line; 3. First shut-off valve of the pigging line; 4. Second shut-off valve of the pigging line; 5. Pigging trunk line; 6. External output shut-off valve; 7. External output trunk line; 8. Pigging launch tube; 11. First shut-off valve of the main cylinder branch; 12. Second shut-off valve of the main cylinder branch; 13. Main cylinder branch; 17. Cylinder connecting pipe; 18. Cylinder connecting shut-off valve; 21. Regulating valve of the main cylinder branch; 22. Flow transmitter of the main cylinder branch; 31. Pressure transmitter; 32. First temperature transmitter; 33. Second temperature transmitter; 34. Third temperature transmitter. Detailed Implementation

[0044] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0045] Example 1:

[0046] This embodiment describes a safe pipeline cleaning and pigging system for hydrogen pipelines, such as... Figure 1As shown, it includes the following components: 1. Hydrogen trunk line within the station; 2. First shut-off valve of the trunk line; 3. First shut-off valve of the pigging pipeline; 4. Second shut-off valve of the pigging pipeline; 5. Pigging trunk line; 6. External output shut-off valve of the external output pipeline; 7. Pigging pigging launch tube; 8. First shut-off valve of the main cylinder branch; 11. Second shut-off valve of the main cylinder branch; 12. Main cylinder branch; 13. Main cylinder connecting pipe; 17. Main cylinder connecting shut-off valve; 18. Regulating valve of the main cylinder branch; 21. Flow transmitter of the main cylinder branch; 22. Pressure transmitter; 31. First temperature transmitter; 32. Second temperature transmitter; 33. Third temperature transmitter; and 34.

[0047] The basic pipeline pigging system consists of the following components: hydrogen trunk line 1, trunk line first shut-off valve 2, pigging first shut-off valve 3, pigging second shut-off valve 4, pigging trunk line 5, external transmission shut-off valve 6, external transmission trunk line 7, pigging launching cylinder 8, main cylinder branch first shut-off valve 11, main cylinder branch second shut-off valve 12, main cylinder branch 13, cylinder connecting pipe 17, and cylinder connecting shut-off valve 18. This system supports long-term transportation, pigging operations, and switching between these functions.

[0048] In this embodiment, the pigging launch tube 8 includes a large tube and a small tube. The first end of the large tube is connected to the first end of the small tube through a large tube-small tube transition tube. The large tube-small tube transition tube is a frustum-shaped tube. The bottom of the large tube-small tube transition tube, the bottom of the large tube, and the bottom of the small tube are located at the same horizontal position. The large tube and the small tube are placed horizontally. A blind plate is provided at the other end of the large tube.

[0049] It should be noted that the terms "large" and "small" in this embodiment refer to the shape-size relationship based on the shape-size relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific size. Therefore, the terms used to describe shape-size in the present invention are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood in conjunction with the accompanying drawings and according to the specific circumstances.

[0050] The large cylinder and the small cylinder are connected by a cylinder connecting pipe 17. One end of the cylinder connecting pipe 17 is connected to the side of the large cylinder near the large cylinder-small cylinder connection pipe, and the other end of the cylinder connecting pipe 17 is connected to the small cylinder. A cylinder connection shut-off valve 18 is installed on the cylinder connecting pipe 17.

[0051] The second end of the small cylinder is connected to the pigging trunk line 5. On the pigging trunk line 5, a first pigging shut-off valve 3 and a second pigging shut-off valve 4 are sequentially installed in the direction away from the small cylinder.

[0052] The end of the pigging trunk line 5 furthest from the small cylinder is connected to the external transmission trunk line 7 and the station's internal hydrogen trunk line 1. An external transmission shut-off valve 6 is installed on the external transmission trunk line 7, and a trunk line first shut-off valve 2 is installed on the side of the internal hydrogen trunk line 1 closest to the pigging trunk line 5. The other end of the internal hydrogen trunk line 1 is connected to a hydrogen pipeline from upstream.

[0053] One end of the large cylinder branch 13 is connected to the side of the hydrogen main line 1 in the station near the upstream hydrogen pipeline, and the other end of the large cylinder branch 13 is connected to the large cylinder. On the hydrogen main line 1 in the station, a first shut-off valve 11 and a second shut-off valve 12 of the large cylinder branch are installed in sequence in the direction of approaching the large cylinder.

[0054] The principle of the pipeline cleaning system is as follows:

[0055] When the pipeline is operating normally, keep the first shut-off valve 11 of the main cylinder branch, the second shut-off valve 12 of the main cylinder branch, the first shut-off valve 3 of the pigging pipeline, and the second shut-off valve 4 of the pigging pipeline closed; keep the first shut-off valve 2 of the main line and the external transfer shut-off valve 6 open.

[0056] Before planned pigging, the pig insertion and replacement operation is carried out first. Specifically, the blind flange of the pig launching cylinder 8 is opened, the pig is placed in the small cylinder, and the internal air is replaced through the replacement pipeline configured in the pig launching cylinder 8. After the replacement is completed, the pig launching cylinder 8 is kept at normal pressure.

[0057] Before the planned pigging operation, hydrogen is filled into the pigging launcher 8. Specifically, the first shut-off valve 11 and the second shut-off valve 12 of the main cylinder branch are opened, while the first shut-off valve 3 and the second shut-off valve 4 of the pigging operation remain closed. High-pressure hydrogen from the station's main hydrogen line 1 is then introduced into the pigging launcher 8, and the cylinder connection shut-off valve 18 is opened.

[0058] After filling is complete, the pigging operation is carried out. Specifically, the first shut-off valve 11 and the second shut-off valve 12 of the main cylinder branch are opened, and the cylinder connection shut-off valve 18 is closed; the first shut-off valve 3 and the second shut-off valve 4 of the pigging are opened, and the first shut-off valve 2 of the main line is closed, so that the medium of the hydrogen main line 1 in the station is introduced into the pigging cylinder, and the pig is pushed out. Then, the first shut-off valve 11, the second shut-off valve 12 of the main cylinder branch, the first shut-off valve 3 of the pigging, and the second shut-off valve 4 of the pigging are kept closed; the first shut-off valve 2 of the main line and the external output shut-off valve 6 are kept open, and the pigging operation is completed.

[0059] In the hydrogen pipeline safe pigging and launching system of this embodiment, the large cylinder branch regulating valve 21 and the large cylinder branch flow transmitter 22 constitute a flow control system. The flow control system is mainly used to monitor and control the flow when the hydrogen trunk line fills the pigging and launching cylinder with gas, so as to avoid the excessive filling flow causing the internal pressure of the pigging and launching cylinder to rise too quickly, and to provide support for limiting the local high temperature during the filling of the pigging and launching cylinder.

[0060] Specifically, the regulating valve 21 of the large cylinder branch is located on the bypass of the second shut-off valve 12 of the large cylinder branch. It is normally closed and only opens when gas is being filled from the large cylinder branch to the pigging cylinder, and is used to control the charging flow rate. The flow transmitter 22 of the large cylinder branch is located on the bypass of the second shut-off valve 12 of the large cylinder branch and is used to detect the charging flow rate of the large cylinder branch.

[0061] In the hydrogen pipeline safety pigging system of this embodiment, pressure transmitter 31, first temperature transmitter 32, second temperature transmitter 33 and third temperature transmitter 34 constitute a pressure and temperature monitoring system. The pressure and temperature monitoring system is used to monitor the pressure and temperature changes during the filling process at multiple points.

[0062] Specifically, the pressure transmitter 31 is located at the end of the large cylinder; the first temperature transmitter 32 is located at the end of the large cylinder; the second temperature transmitter 33 is located near the transition pipe between the large and small cylinders; and the third temperature transmitter 34 is located at the end of the small cylinder. Each temperature transmitter and pressure transmitter is used to detect the temperature and pressure at the corresponding location in real time.

[0063] The working principle of this invention is as follows:

[0064] The pipeline cleaning function of hydrogen pipelines is a fundamental element supporting pipeline integrity management, making it necessary to include cleaning operation functionality. Similar to natural gas pipelines, hydrogen pipelines generally require functions such as pipeline cleaning, metering, safety shut-off, and dust removal. In terms of medium physical characteristics, hydrogen exhibits a significant anti-coke-Thomson effect compared to natural gas. This means that after pressure regulation and throttling in the pipeline, the medium temperature remains essentially constant, while natural gas experiences a significant temperature drop. Therefore, conventional natural gas pipelines pay particular attention to pressure regulation during operation, focusing on the temperature drop and low temperature issues caused by throttling. In contrast, due to the unique anti-coke-Thomson effect of hydrogen, the temperature drop caused by pressure regulation and throttling does not need to be considered during hydrogen operation. During pipeline cleaning, high-pressure hydrogen needs to be introduced from the main pipeline into the purged atmospheric pressure pigging system to establish a pressure almost equal to that of the downstream pipeline before the pig can be deployed. During this process, the high-pressure hydrogen, maintaining an almost constant temperature after throttling, enters the cleaning system, continuously increasing the system pressure—a typical pressure filling process. Because hydrogen exhibits a unique anti-Jack-Thomson effect and follows the gas laws of conventional gases, this pressurization process is similar to drastically pressurizing initially introduced low-pressure, room-temperature hydrogen. Compared to natural gas, hydrogen, at the same pressure ratio and initial temperature, reaches a much higher temperature after pressurization. Therefore, this could cause excessively high temperatures in some parts of the gas, leading to material degradation in pipeline materials and seals within the pigging system, posing a safety risk.

[0065] This invention addresses the issues of the reverse coke-sodium effect of hydrogen and the severe temperature rise during the pressurization process by setting up a flow control system, which controls the injection rate through regulating valves to avoid the formation of an "adiabatic expansion" scenario; and by setting up a pressure and temperature monitoring system to detect the temperature at multiple points and directly guide the operation process.

[0066] Example 2:

[0067] This embodiment describes a safe pipeline cleaning and pigging method for hydrogen pipelines, such as... Figure 2 As shown, it includes the following steps:

[0068] Step 1: During normal pipeline operation, all valves remain in their initial state. The specific initial state of each valve is as follows:

[0069] Keep the first shut-off valve 11, the second shut-off valve 12, the regulating valve 21, the first shut-off valve 3, and the second shut-off valve 4 of the main cylinder branch closed; keep the first shut-off valve 2 of the main line and the external output shut-off valve 6 open.

[0070] In the initial state of the valve, hydrogen from upstream flows sequentially through the station's hydrogen main line 1 and the external transmission main line 7.

[0071] Step Two: Before planned pigging, perform pig insertion and replacement operations. The specific process of pig insertion and replacement is as follows:

[0072] Open the blind flange of the pigging launcher 8, place the pig into the small cylinder, and perform internal air replacement through the replacement pipeline configured in the pigging launcher 8. After replacement, the pigging launcher 8 is kept at normal pressure. In this embodiment, the replacement pipeline is the cylinder connecting pipe 17, which balances the air pressure between the large and small cylinders inside the pigging launcher 8.

[0073] Step 3: Before the planned pigging operation, perform hydrogen filling of the pigging launcher 8. The specific process for hydrogen filling is as follows:

[0074] Open the first shut-off valve 11 of the main cylinder branch, while keeping the second shut-off valve 12 of the main cylinder branch, the first shut-off valve 3 of the pigging pipeline, and the second shut-off valve 4 of the pigging pipeline closed. Open the regulating valve 21 of the main cylinder branch, and the high-pressure hydrogen in the hydrogen trunk line 1 in the station is filled into the pigging launcher 8. Open the cylinder connection shut-off valve 18 and monitor the temperature of the temperature transmitter.

[0075] During hydrogen filling, hydrogen from upstream enters the pigging and launching cylinder 8 sequentially through the first shut-off valve 11 of the large cylinder branch and the regulating valve 21 of the large cylinder branch. The gas pressure inside the large and small cylinders of the pigging and launching cylinder 8 is balanced through the cylinder connection shut-off valve 18.

[0076] When the temperature exceeds the maximum design operating temperature of the pigging launcher, immediately close the main cylinder branch regulating valve 21. Specifically, when any temperature transmitter detects a local temperature higher than the preset maximum operating temperature, immediately close the main cylinder branch regulating valve 21. When all temperature transmitters detect a temperature lower than the set maximum operator temperature, then open the main cylinder branch regulating valve 21 to perform the hydrogen filling operation.

[0077] This alternating operation continues until the pressure inside the pigging and launching cylinder 8 rises to near the pressure of the hydrogen main line 1 in the station, indicating that the pressure filling is complete and the pressure of the large cylinder and the small cylinder have reached equilibrium.

[0078] A pressure transmitter 31 is used to monitor the pressure inside the pigging launcher 8 to determine whether hydrogen filling is complete. In this embodiment, when the pressure difference between the pigging launcher 8 and the main line pressure is within ±3% of the main line pressure, it indicates that the pressure inside the pigging launcher 8 has risen to near the pressure of the hydrogen main line 1 in the station.

[0079] Furthermore, in this embodiment, when operating the branch regulating valve, the flow transmitter data is monitored, and the flow velocity in the downstream pipeline of the regulating valve must not exceed 30m / s.

[0080] Step 4: After filling is complete, perform the pipeline cleaning operation, specifically as follows:

[0081] Open the first shut-off valve 11 and the second shut-off valve 12 of the main cylinder branch, close the regulating valve 21 and the cylinder connection shut-off valve 18 of the main cylinder branch, open the first shut-off valve 3 and the second shut-off valve 4 of the pigging pipeline, close the first shut-off valve 2 of the main line, introduce the medium of the main line 1 into the pig launching cylinder, and push out the pigging device. Then restore the valve status of step one to complete the pigging operation.

[0082] Based on the typical reverse coke-like properties of hydrogen and combined with the temperature rise law of gas adiabatic compression, this embodiment identifies the short-term high temperature characteristics that may exist in the pigging operation of hydrogen pipelines. By setting up systems such as flow control and temperature monitoring, it can effectively overcome the problem of local gas high temperature during the filling and pressurization process of high-pressure hydrogen from the trunk line to the atmospheric pressure pigging cylinder, avoid using excessively high-grade materials or causing operational risks to pipes, seals, pigs, etc., and ensure the safe implementation of hydrogen pipeline pigging operations.

[0083] It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A safe pipeline cleaning and launching system for hydrogen pipelines, comprising a pipeline cleaning circuit, wherein the cleaning and launching cylinder (8) in the pipeline cleaning circuit forms a circuit with the main hydrogen pipeline (1), the main cylinder branch (13), and the main cleaning pipeline (5) within the station, characterized in that, The pipeline pigging circuit is equipped with: The flow control unit is located on the bypass of the shut-off valve of the large cylinder branch between the upstream hydrogen pipeline and the pigging cylinder (8) to detect and control the pressurization flow rate; the flow control unit includes the large cylinder branch regulating valve and the large cylinder branch flow transmitter. The pressure monitoring unit is installed at the blind flange port of the pigging launcher (8) to monitor the pressure at the port; Temperature monitoring units are distributed along the pigging direction of the pigging launcher (8) to monitor the temperature at each location; the temperature monitoring unit includes several temperature transmitters; the temperature transmitters are respectively set along the gas flow direction to detect the local temperature at each location inside the pigging launcher in real time. During the hydrogen filling process inside the pigging and launching cylinder, the temperature transmitter continuously monitors the temperature. When the detected local temperature is higher than the preset maximum operating temperature, the main cylinder branch regulating valve is closed. The hydrogen filling operation is then performed again when the temperature values ​​monitored by all temperature transmitters are lower than the set maximum operating temperature.

2. The hydrogen pipeline safety pigging and launching system according to claim 1, characterized in that, The pressure monitoring unit includes a pressure transmitter (31), which is located at the port of the pigging tube (8).

3. The hydrogen pipeline safety pigging and launching system according to claim 1, characterized in that, The temperature monitoring unit includes several temperature transmitters; the first temperature transmitter (32) is located at the port of the pigging launcher (8); the second temperature transmitter (33) is located at the width change point of the pigging launcher (8); and the third temperature transmitter (34) is located at the other end away from the port of the pigging launcher (8).

4. A hydrogen pipeline safety pigging and launching system according to claim 1, 2, or 3, characterized in that, The flow control unit includes a large cylinder branch regulating valve (21) and a large cylinder branch flow transmitter (22); the large cylinder branch (13) is located between the pigging and launching cylinder (8) and the upstream hydrogen pipeline, and several shut-off valves are installed on the large cylinder branch (13). The large cylinder branch regulating valve (21) and the large cylinder branch flow transmitter (22) are located on the bypass of the same shut-off valve.

5. A hydrogen pipeline safety pigging and launching system according to claim 1, 2, or 3, characterized in that, The pipeline cleaning circuit includes a pigging launcher (8), which includes a large cylinder and a small cylinder with different diameters; the large cylinder and the small cylinder are connected by a transition pipe.

6. A hydrogen pipeline safety pigging and launching system according to claim 5, characterized in that, One end of the small cylinder is connected to the pigging main line (5), and the large cylinder branch line (13) is set between the upstream hydrogen pipeline and the large cylinder; the station hydrogen main line (1) is set between the large cylinder branch line (13) and the pigging branch line (5).

7. A hydrogen pipeline safety pigging and launching system according to claim 1 or 6, characterized in that, The main pipeline (5) is equipped with a first shut-off valve (3) and a second shut-off valve (4) in sequence; the hydrogen main pipeline (1) in the station is equipped with a first shut-off valve (2); the main pipeline branch (13) is equipped with a first shut-off valve (11) and a second shut-off valve (12) in sequence.

8. A method for safe pigging and launching of hydrogen pipelines, employing a safe pigging and launching system for hydrogen pipelines as described in any one of claims 1-7, characterized in that, Includes the following steps: S1: Initialize the hydrogen pipeline safety pigging system, close the shut-off valves on each branch, and open the shut-off valves on the main hydrogen pipeline and the external transmission pipeline within the station. S2: Before planned pigging, perform pig insertion and replacement operations; perform hydrogen filling operation inside the pigging launcher; control the flow rate based on the real-time monitored temperature and pressure values ​​compared with thresholds; S3: Hydrogen filling is complete, real-time pigging operation begins; the shut-off valves on the main cylinder branch and the pigging branch are opened; the shut-off valve on the hydrogen main line in the station is closed, the medium is introduced into the pigging launcher, and the pig is launched.

9. A method for safe pipeline cleaning and pigging of hydrogen pipelines according to claim 8, characterized in that, The pig insertion and replacement operation is specifically as follows: Open the blind flange of the pigging launcher, place the pig into the small cylinder, and replace the internal air through the replacement pipeline configured in the pigging launcher.

10. A method for safe pipeline cleaning and pigging of hydrogen pipelines according to claim 8, characterized in that, The hydrogen filling operation inside the pigging and launching tube specifically includes: Open the first shut-off valve of the main cylinder branch, while keeping the second shut-off valve of the main cylinder branch, the first shut-off valve of the pigging pipeline, and the second shut-off valve of the pigging pipeline closed; Open the main cylinder branch regulating valve to fill the high-pressure hydrogen in the station's hydrogen trunk line into the pigging and launching cylinder, and open the cylinder connection shut-off valve. Monitor the temperature transmitter. When the temperature exceeds the maximum design operating temperature of the pigging cylinder, immediately close the regulating valve of the main cylinder branch.

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