A gas-accumulation-free water outlet pipe, a pipeline system and a gas-accumulation-free method

Abstract

The application provides a kind of no gas water outlet pipe, pipeline system and no gas method, comprising: upper section water outlet pipe (1) and lower section water outlet pipe (2);Upper section water outlet pipe (1) and lower section water outlet pipe (2) are vertically arranged with ground;Upper section water outlet pipe (1) includes: water inlet pipe (1.1), water flow outlet pipe (1.2) and elbow pipe (1.3), elbow pipe (1.3) is n type structure;Water inlet pipe and water flow outlet pipe (1.2) are connected by elbow pipe (1.3);Water flow outlet pipe (1.2) is connected with lower section water outlet pipe (2) after being connected with water outlet of converter valve;Water inlet pipe (1.1) and lower section water outlet pipe (2) are each provided with water inlet, and each water inlet is connected with each branch pipe of converter valve;The structure of the application is improved, so that a part of cooling medium in water inlet pipe is driven by gas bubble from bottom to top and flows into lower section water outlet pipe (2), and then is collected with another part of cooling medium flowing into lower section water outlet pipe (2), so that the flow is increased to discharge gas bubble.

Description

Technical Field

[0001] This invention patent relates to the field of power electronics manufacturing technology, specifically to a non-air-accumulating water outlet pipe, pipeline system, and non-air-accumulating method. Background Technology

[0002] The flexible DC converter valve is a core piece of equipment in DC transmission projects. To ensure effective heat dissipation of the IGBT power devices in the converter valve, water cooling is configured for it. The cooling pipeline is an important part of the cooling system. The cooling medium at a certain flow rate is pressurized by the water pump and enters the heat sink of the IGBT power device to be cooled through the power equipment cooling pipeline, carrying away the heat generated by the power device. Then the cooling medium enters the outdoor heat exchange equipment, where the heat is discharged into the air. The cooled low-temperature medium is then pressurized by the water pump and enters the power device to be cooled, forming a closed loop to ensure that the operating temperature of the power device of the flexible DC converter valve is within the safe operating range.

[0003] The existing cooling water piping for flexible DC converter valves mainly includes the main inlet pipe, main return pipe, branch pipes, electrodes, flanged straight tees, butterfly valves, and vent valves. Currently, flexible DC transmission projects suffer from severe air accumulation in the water-cooled piping, resulting in low system venting efficiency. Recently, several converter stations have experienced converter valve closure due to leaks in the vent valves. Air accumulation in the piping poses a serious hazard, specifically including: ① If gas is trapped in the pipeline for a long time without being discharged, it reduces the cross-section of the water flow. In severe cases, it may even cut off most of the water flow, causing difficulties in water supply or even pipe bursting.

[0004] ② Air accumulation in the pipeline can easily lead to water hammer during pump switching, causing severe vibration in the pipeline, which can seriously damage the pipeline.

[0005] ③ The gas in the pipeline increases the local water flow resistance, causing uneven water flow distribution among modules, affecting heat dissipation, and in severe cases, causing the IGBT junction temperature to be too high.

[0006] ④ If gas accumulates inside the module, it is detrimental to insulation and can easily cause water pipes to break down, leading to water leakage.

[0007] ⑤ Gas accumulation in the pipeline accelerates electrode corrosion and scaling, affecting electrode lifespan and increasing maintenance frequency and difficulty.

[0008] Therefore, air accumulation in the converter valve water cooling system and potential leakage in the vent valve are serious hidden dangers affecting the reliable operation of DC projects. Currently, on-site venting mainly relies on commissioning personnel manually venting based on experience, which is extremely inefficient and cannot completely solve the problem. Therefore, the issue of air accumulation in pipelines urgently needs to be studied and resolved. Summary of the Invention

[0009] To overcome the problem of severe air accumulation in the cooling water pipes of existing flexible DC converter valves, this invention proposes an air-free water outlet pipe, comprising: Upper water outlet pipe (1) and lower water outlet pipe (2); both the upper water outlet pipe (1) and the lower water outlet pipe (2) are arranged perpendicular to the ground; The upper water outlet pipe (1) includes: an inlet pipe (1.1), a water outlet pipe (1.2), and a bend (1.3), wherein the bend (1.3) has an n-shaped structure; the inlet pipe and the water outlet pipe (1.2) are connected by the bend (1.3); The water outlet pipe (1.2) is connected to the outlet of the converter valve after being connected to the lower water outlet pipe (2); Both the inlet pipe (1.1) and the lower outlet pipe (2) are equipped with inlets, and each inlet is connected to a branch pipe of the converter valve. The cooling medium containing air bubbles flows into the inlet pipe (1.1) after passing through a branch pipe connected to the inlet pipe (1.1). The water and air in the inlet pipe (1.1) move in the same direction, and the cooling medium flows from bottom to top, pushing the gas through the bend (1.3) and into the water outlet pipe (1.2) and the lower outlet pipe (2). The water and air in the lower outlet pipe (2) move in opposite directions, and the cooling medium flows from top to bottom. After merging with part of the cooling medium flowing into the lower outlet pipe (2), the gas is driven to flow out through the converter valve.

[0010] Preferably, when the water inlet pipe (1.1) includes two water inlets, the water inlet pipe (1.1) includes a water flow inlet pipe (1.1.1), and the water outlet pipe further includes several flanges and straight tees; Both ends of the water inlet pipe (1.1.1) are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the water inlet pipe (1.1.1) is the water inlet; The lower port of the straight tee near the ground connected to the water inlet pipe (1.1.1) is closed; The upper port of the straight tee, which is far from the ground and connected to the water inlet pipe (1.1.1), is connected to the bend (1.3).

[0011] Preferably, when the water inlet pipe (1.1) includes two or more water inlets, the water inlet pipe (1.1) includes several water inlet pipes (1.1.1), and the water outlet pipe also includes several flanges and straight tees; Both ends of several water inlet pipes (1.1.1) are connected to the upper or lower port of a straight tee via flanges, and the flanges and straight tees are connected in series to form a pipeline; The side port of the straight tee connected to the aforementioned water inlet pipes (1.1.1) is the water inlet; The lower port of the straight tee near the ground in the pipeline is closed, and the upper port of the straight tee away from the ground is connected to the bend (1.3) through a flange.

[0012] Preferably, when the water inlet pipe (1.1) includes a water inlet, the water inlet pipe (1.1) does not have a water flow inlet pipe (1.1.1), the water inlet pipe (1.1) includes a straight tee, and the water outlet pipe further includes several flanges and straight tees; The inlet of the water inlet pipe (1.1) is a side port of a straight tee. The upper port of the straight tee is connected to the bend pipe (1.3) through a flange, and the lower port is closed.

[0013] Preferably, when the lower water outlet pipe (2) includes two water inlets, the number of the lower water outlet pipe (2) is one section, and the water outlet pipe also includes several flanges and straight tees; Both ends of the lower water outlet pipe (2) are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the lower outlet pipe (2) is the inlet; The upper end of the straight tee far from the ground, which is connected to the lower water outlet pipe (2), is connected to the water outlet pipe (1.2) via a flange; The lower port of the straight tee near the ground, which is connected to the lower section of the water outlet pipe (2), is connected to the outlet of the converter valve through a flange.

[0014] Preferably, when the lower water outlet pipe (2) includes two or more water inlets, the number of the lower water outlet pipe (2) is several segments, and the water outlet pipe also includes several flanges and straight tees; Both ends of each lower section of the water outlet pipe (2) are connected to the upper or lower port of the straight tee through flanges, and a water outlet pipeline is formed by connecting the flanges and the straight tee in series. The side port of the straight tee connected to the lower outlet pipe (2) is the inlet; The upper end of the straight tee in the water outlet pipeline that is far from the ground is connected to the water outlet pipeline (1.2) through a flange, and the lower end of the straight tee that is close to the ground is connected to the outlet of the converter valve through a flange.

[0015] Preferably, when the lower water outlet pipe (2) includes a water inlet, the water outlet pipe does not have a lower water outlet pipe (2), the water inlet is a side port of a straight tee, and the water outlet pipe also includes several flanges and straight tees; The upper port of the straight tee is connected to the water outlet pipe (1.2) via a flange, and the lower port is connected to the outlet of the converter valve via a flange.

[0016] Preferably, the bend (1.3) and the water outlet pipe (1.2) are integrally formed or connected by a flange.

[0017] Based on the same inventive concept, the present invention also provides a non-gas-accumulation flexible direct current converter valve pipeline system, characterized in that it includes: The main inlet pipe (3) and the main outlet pipe, as well as multiple branch pipes, are arranged perpendicular to the ground. The main water outlet pipe adopts a non-air-accumulating water outlet pipe as described above; The inlet of the main water inlet pipe (3) is connected to the cooling medium source; The main inlet pipe (3) has multiple outlets on its pipe wall; Each branch pipe is respectively set and fixed between each outlet of the main water inlet pipe (3) and each inlet of the main water outlet pipe.

[0018] Preferably, each branch pipe is respectively installed and fixed between each outlet of the main inlet pipe (3) and each inlet of the main outlet pipe, including: The inlet of each branch pipe is located either below or at the same height as the outlet of the branch pipe.

[0019] Preferably, each branch pipe is equipped with several radiators.

[0020] Based on the same inventive concept, this invention also provides a method for preventing air accumulation in a flexible DC converter valve pipeline, characterized in that the method is implemented using a non-air-accumulation flexible DC converter valve pipeline system as described above, comprising: Cooling medium containing air bubbles flows upward through the main inlet pipe (3) arranged vertically to the ground into multiple branch pipes for convective heat exchange. After convective heat exchange, the cooling medium is divided into two parts by the multiple branch pipes. One part of the cooling medium flows upward into the inlet pipe (1.1) in the same direction as the air bubbles, and after passing through the bend pipe (1.3), it flows into the water outlet pipe (1.2). In the water outlet pipe (1.2), the cooling medium flows downward, carrying the air bubbles into the lower outlet pipe (2), where it merges with the other part of the cooling medium flowing into the lower outlet pipe (2) and carries the air bubbles away.

[0021] Compared with the closest existing technology, the present invention has the following beneficial effects: This invention proposes a non-air-accumulating water outlet pipe, a piping system, and a non-air-accumulating method, comprising: an upper water outlet pipe (1) and a lower water outlet pipe (2); both the upper water outlet pipe (1) and the lower water outlet pipe (2) are arranged perpendicular to the ground; the upper water outlet pipe (1) includes: an inlet pipe (1.1), a water outlet pipe (1.2), and a bend (1.3), the bend (1.3) being an n-shaped structure; the inlet pipe and the water outlet pipe (1.2) are connected by the bend (1.3); the water outlet pipe (1.2) is connected to the lower water outlet pipe (2) and then connected to the outlet of a converter valve; the inlet pipe... Both (1.1) and the lower water outlet pipe (2) are equipped with water inlets, and each water inlet is connected to a branch pipe of the converter valve. The cooling medium with air bubbles flows into the water inlet pipe (1.1) after passing through a branch pipe connected to the water inlet pipe (1.1). The water and air in the water inlet pipe (1.1) are in the same direction, and the cooling medium flows from bottom to top, pushing the gas through the bend pipe (1.3) and into the water outlet pipe (1.2) and the lower water outlet pipe (2). The water and air in the lower water outlet pipe (2) are in opposite directions, and the cooling medium flows from top to bottom. After merging with part of the cooling medium flowing into the lower water outlet pipe (2), the gas is driven to flow out through the converter valve. This invention improves the structure of the main return water pipe of the flexible DC converter valve by dividing it into upper and lower parts. The water flow direction in the upper part of the pipe is from bottom to top, while the water flow direction in the lower part of the pipe is from top to bottom. This ensures that the air and water flow in the upper part of the main return water pipe are in the same direction, pushing the gas into the lower part of the return water pipe. The cooling medium in the lower part of the return water pipe undergoes multiple confluences, resulting in a large flow rate and high velocity, which effectively carries away the air bubbles. This effectively solves the problem of severe air accumulation in the water-cooled pipes of current flexible DC transmission projects. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a non-air-accumulating water outlet pipe structure provided by the present invention; Figure 2 A schematic diagram of a non-gas-accumulation flexible direct current converter valve piping system provided by the present invention; Figure 3 This invention provides a schematic diagram of the cooling medium flow direction in a non-gas-accumulating pipeline system. Detailed Implementation

[0023] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] Example 1: A schematic diagram of a non-air-accumulating water outlet pipe provided by the present invention is shown below. Figure 1 As shown, it includes: Upper water outlet pipe 1 and lower water outlet pipe 2; both the upper water outlet pipe 1 and the lower water outlet pipe 2 are arranged perpendicular to the ground; The upper water outlet pipe 1 includes: an inlet pipe 1.1, a water outlet pipe 1.2, and a bend 1.3, wherein the bend 1.3 has an n-shaped structure; the inlet pipe and the water outlet pipe 1.2 are connected by the bend 1.3. The water outlet pipe 1.2 is connected to the lower outlet pipe 2 and then connected to the outlet of the converter valve; Both the inlet pipe 1.1 and the lower outlet pipe 2 are equipped with inlets, and each inlet is connected to a branch pipe of the converter valve. The cooling medium containing air bubbles flows into the water inlet pipe 1.1 after passing through a branch pipe connected to the water inlet pipe 1.1. The water and air in the water inlet pipe 1.1 move in the same direction, and the cooling medium flows from bottom to top, pushing the gas through the bend 1.3 and into the water outlet pipe 1.2 and the lower water outlet pipe 2. The water and air in the lower water outlet pipe 2 move in opposite directions, and the cooling medium flows from top to bottom. After merging with part of the cooling medium flowing into the lower water outlet pipe 2, the gas is driven to flow out through the converter valve.

[0025] Wherein, when the water inlet pipe 1.1 includes two water inlets, the water inlet pipe 1.1 includes a water flow inlet pipe 1.1.1, and the water outlet pipe also includes several flanges and straight tees; Both ends of the water inlet pipe 1.1.1 are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the water inlet pipe 1.1.1 is the water inlet; The lower port of the straight tee near the ground connected to the water inlet pipe 1.1.1 is closed; The upper port of the straight tee, which is far from the ground and connected to the water inlet pipe 1.1.1, is connected to the bend pipe 1.3.

[0026] Wherein, when the water inlet pipe 1.1 includes two or more water inlets, the water inlet pipe 1.1 includes several water inlet pipes 1.1.1, and the water outlet pipe also includes several flanges and straight tees; Both ends of several water inlet pipes 1.1.1 are connected to the upper or lower port of a straight tee via flanges, and the flanges and straight tees are connected in series to form a pipeline; The side port of the straight tee connected to the aforementioned water inlet pipes 1.1.1 is the water inlet; The lower port of the straight tee near the ground in the pipeline is closed, and the upper port of the straight tee away from the ground is connected to the bend 1.3 via a flange.

[0027] Wherein, when the water inlet pipe 1.1 includes a water inlet, the water inlet pipe 1.1 does not have a water flow inlet pipe 1.1.1, the water inlet pipe 1.1 includes a straight tee, and the water outlet pipe also includes several flanges and straight tees; The inlet of the water inlet pipe 1.1 is a side port of a straight tee. The upper port of the straight tee is connected to the bend pipe 1.3 through a flange, and the lower port is closed.

[0028] Wherein, when the lower water outlet pipe 2 includes two water inlets, the number of lower water outlet pipes 2 is one section, and the water outlet pipe also includes several flanges and straight tees; Both ends of the lower water outlet pipe 2 are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the lower water outlet pipe 2 is the water inlet; The upper end of the straight tee, which is far from the ground and connected to the lower water outlet pipe 2, is connected to the water outlet pipe 1.2 via a flange; The lower port of the straight tee near the ground, which is connected to the lower section of the water outlet pipe 2, is connected to the outlet of the converter valve via a flange.

[0029] Wherein, when the lower water outlet pipe 2 includes two or more water inlets, the number of the lower water outlet pipe 2 is several sections, and the water outlet pipe also includes several flanges and straight tees; Both ends of each lower section of the water outlet pipe 2 are connected to the upper or lower port of a straight tee via flanges, and the flanges and straight tee are connected in series to form a water outlet pipeline; The side port of the straight tee connected to the lower water outlet pipe 2 is the water inlet; In the aforementioned water outlet pipeline, the upper port of the straight tee furthest from the ground is connected to the water outlet pipeline 1.2 via a flange, and the lower port of the straight tee closest to the ground is connected to the outlet of the converter valve via a flange.

[0030] Wherein, when the lower section water outlet pipe 2 includes a water inlet, the water outlet pipe does not have a lower section water outlet pipe 2, the water inlet is a side port of a straight tee, and the water outlet pipe also includes several flanges and straight tees; The upper port of the straight tee is connected to the water outlet pipe 1.2 via a flange, and the lower port is connected to the outlet of the converter valve via a flange.

[0031] The bend 1.3 and the water outlet pipe 1.2 are integrally installed or connected by a flange.

[0032] Example 2: Based on the same inventive concept, this invention also provides a non-gas-accumulation flexible DC converter valve piping system. A schematic diagram of the structure of the non-gas-accumulation flexible DC converter valve piping system provided by this invention is shown below. Figure 2 As shown in the diagram, the flow direction of the cooling medium in the pipeline system of the non-gas-accumulation flexible direct converter valve is as follows: Figure 3 As shown, it includes: The main inlet pipe 3 and the main outlet pipe, as well as multiple branch pipes, are arranged perpendicularly to the ground. The main water outlet pipe adopts a non-air-accumulating water outlet pipe as described above; The inlet of the main water inlet pipe 3 is connected to the cooling medium source; The main water inlet pipe 3 has multiple water outlets on its pipe wall; Each branch pipe is respectively installed and fixed between each outlet of the main water inlet pipe 3 and each inlet of the main water outlet pipe.

[0033] Each branch pipe is respectively installed and fixed between each outlet of the main inlet pipe 3 and each inlet of the main outlet pipe, including: The inlet of each branch pipe is located either below or at the same height as the outlet of the branch pipe.

[0034] Each of the branch pipes is equipped with several radiators.

[0035] Specifically, the main inlet water pipe flows from bottom to top. The main return water pipe is divided into upper and lower sections. The upper section initially flows from bottom to top, then changes direction to top to bottom via a bend, before connecting in series with the lower section of the main return water pipe. The internal water flow is from top to bottom. The main inlet water pipe is arranged vertically to the ground, with its bottom end connected to a butterfly valve via a flange. The remaining pipe sections are connected to the inter-floor branch pipes via flanged tees. The main return water pipe is also arranged vertically to the ground, with its bottom end connected to a butterfly valve via a flange. The remaining pipe sections are connected to the inter-floor branch pipes via flanged tees. The branch pipes typically span 4-5 floors and are arranged in a series-parallel configuration. They mainly include inter-floor module water pipes and radiator water pipes. The sub-module radiator pipes are connected in series, while other pipes are arranged in parallel.

[0036] Cooling water flows in from the bottom of the main inlet pipe on the left, flows upward, and then flows layer by layer into five horizontal branch pipes. The cooling water in the branch pipes flows sequentially through several radiators connected in series. The cooling water from the top three branch pipes converges into the upper part of the main return pipe on the right, flows upward to the top, and then turns downward along a bend. The cooling water from the bottom two branch pipes converges into the lower part of the main return pipe on the right, flowing downward to the bottom of the main return pipe. The water in the upper part of the main return pipe turns downward at the top along a bend, then connects with the lower part of the main return pipe, flowing towards the bottom of the main return pipe.

[0037] Example 3: Based on the same inventive concept, this invention also provides a method for preventing air accumulation in the pipeline of a flexible DC converter valve, comprising: Cooling medium containing air bubbles flows upward through the main inlet pipe 3, which is arranged vertically to the ground, into multiple branch pipes for convective heat exchange. After convective heat exchange, the cooling medium is divided into two parts by the multiple branch pipes. One part of the cooling medium flows upward into the inlet pipe 1.1 in the same direction as the air bubbles, and after passing through the bend 1.3, it flows into the outlet pipe 1.2. In the outlet pipe 1.2, the cooling medium flows downward, carrying the air bubbles into the lower outlet pipe 2. After merging with the other part of the cooling medium flowing into the lower outlet pipe 2, the air bubbles are carried away.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the scope of protection of the claims pending approval.

Claims

1. A non-gas-accumulating flexible direct current converter valve piping system, characterized in that, include: The main inlet pipe (3) and the main outlet pipe, as well as multiple branch pipes, are arranged perpendicular to the ground. The main water outlet pipe is an air-free water outlet pipe; The inlet of the main water inlet pipe (3) is connected to the cooling medium source; The main inlet pipe (3) has multiple outlets on its pipe wall; Each branch pipe is respectively installed and fixed between each outlet of the main inlet pipe (3) and each inlet of the main outlet pipe; The air-free water outlet pipe includes: Upper water outlet pipe (1) and lower water outlet pipe (2); both the upper water outlet pipe (1) and the lower water outlet pipe (2) are arranged perpendicular to the ground; The upper water outlet pipe (1) includes: an inlet pipe (1.1), a water outlet pipe (1.2), and a bend (1.3), wherein the bend (1.3) has an n-shaped structure; the inlet pipe and the water outlet pipe (1.2) are connected by the bend (1.3); The water outlet pipe (1.2) is connected to the outlet of the converter valve after being connected to the lower water outlet pipe (2); Both the inlet pipe (1.1) and the lower outlet pipe (2) are equipped with inlets, and each inlet is connected to a branch pipe of the converter valve. The cooling medium containing air bubbles flows into the water inlet pipe (1.1) after passing through a branch pipe connected to the water inlet pipe (1.1). The water and air in the water inlet pipe (1.1) move in the same direction, and the cooling medium flows from bottom to top, pushing the gas through the bend pipe (1.3) and into the water outlet pipe (1.2) and the lower water outlet pipe (2). The water and air in the lower water outlet pipe (2) move in opposite directions, and the cooling medium flows from top to bottom. After merging with part of the cooling medium flowing into the lower water outlet pipe (2), the gas is driven to flow out through the outlet of the converter valve. When the water inlet pipe (1.1) includes two water inlets, the water inlet pipe (1.1) includes a water flow inlet pipe (1.1.1), and the upper water outlet pipe also includes several flanges and straight tees; Both ends of the water inlet pipe (1.1.1) are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the water inlet pipe (1.1.1) is the water inlet; The lower port of the straight tee near the ground connected to the water inlet pipe (1.1.1) is closed; The upper end of the straight tee, which is far from the ground and connected to the water inlet pipe (1.1.1), is connected to the bend (1.3); When the lower water outlet pipe (2) includes two water inlets, the number of the lower water outlet pipe (2) is one section, and the lower water outlet pipe also includes several flanges and straight tees; Both ends of the lower water outlet pipe (2) are connected to the upper or lower port of a straight tee via flanges; The side port of the straight tee connected to the lower outlet pipe (2) is the inlet; The upper end of the straight tee far from the ground, which is connected to the lower water outlet pipe (2), is connected to the water outlet pipe (1.2) via a flange; The lower port of the straight tee near the ground, which is connected to the lower section of the water outlet pipe (2), is connected to the outlet of the converter valve through a flange.

2. The system as described in claim 1, characterized in that, When the water inlet pipe (1.1) includes two or more water inlets, the water inlet pipe (1.1) includes several water inlet pipes (1.1.1), and the upper outlet pipe also includes several flanges and straight tees; Both ends of several water inlet pipes (1.1.1) are connected to the upper or lower port of a straight tee via flanges, and the flanges and straight tees are connected in series to form a pipeline; The side port of the straight tee connected to the aforementioned water inlet pipes (1.1.1) is the water inlet; The lower port of the straight tee near the ground in the pipeline is closed, and the upper port of the straight tee away from the ground is connected to the bend (1.3) through a flange.

3. The system as described in claim 1, characterized in that, When the lower water outlet pipe (2) includes two or more water inlets, the number of the lower water outlet pipe (2) is several sections, and the lower water outlet pipe also includes several flanges and straight tees; Both ends of each lower section of the water outlet pipe (2) are connected to the upper or lower port of the straight tee through flanges, and a water outlet pipeline is formed by connecting the flanges and the straight tee in series. The side port of the straight tee connected to the lower outlet pipe (2) is the inlet; The upper end of the straight tee in the water outlet pipeline that is far from the ground is connected to the water outlet pipeline (1.2) through a flange, and the lower end of the straight tee that is close to the ground is connected to the outlet of the converter valve through a flange.

4. The system as described in claim 1, characterized in that, The bend (1.3) and the water outlet pipe (1.2) are either integrally installed or connected by a flange.

5. The system as described in claim 1, characterized in that, Each branch pipe is respectively installed and fixed between each outlet of the main inlet pipe (3) and each inlet of the main outlet pipe, including: The inlet of each branch pipe is located either below or at the same height as the outlet of the branch pipe.

6. The system as described in claim 5, characterized in that, Each of the branch pipes is equipped with several radiators.

7. A method for preventing air accumulation in the pipeline of a flexible DC converter valve, characterized in that, The method for eliminating air accumulation in a flexible DC converter valve pipeline is implemented using an air-accumulation-free flexible DC converter valve pipeline system as described in any one of claims 1 to 6, comprising: Cooling medium containing air bubbles flows upward through the main inlet pipe (3) arranged vertically to the ground into multiple branch pipes for convective heat exchange. After convective heat exchange, the cooling medium is divided into two parts by the multiple branch pipes. One part of the cooling medium flows upward into the inlet pipe (1.1) in the same direction as the air bubbles, and after passing through the bend pipe (1.3), it flows into the water outlet pipe (1.2). In the water outlet pipe (1.2), the cooling medium flows downward, carrying the air bubbles into the lower outlet pipe (2), where it merges with the other part of the cooling medium flowing into the lower outlet pipe (2) and carries the air bubbles away.

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