Deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device and method

Abstract

The present invention provides a gravity trap collection device and method for SF6 leakage gas in a deep underground GIL power pipe gallery. Through the synergistic effect of a heavy gas particle trap and a micro-pressure air system, and by utilizing the characteristic that the density of SF6 gas is large, a 0-pressure or micro-negative pressure collection space is formed in the heavy gas particle trap, significantly improving the capture efficiency of SF6 heavy gas particles; combined with the linkage control of the SF6 gas leakage monitoring mechanism and the micro-pressure air system, a closed-loop management of real-time leakage detection - automatic startup - rapid collection is realized, reducing the need for manual intervention, greatly enhancing the automation of SF6 gas leakage recovery, reducing greenhouse gas emissions, and at the same time avoiding potential safety hazards caused by the accumulation of SF6 gas in the pipe gallery. The present invention combines the principle of gravity sedimentation with fluid dynamics, and through structural optimization and system coordination, realizes the passive capture and active recovery of SF6 heavy gas, and is extremely suitable for the emergency treatment of dangerous heavy gas leakage in limited spaces such as deep underground pipe galleries.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechatronic engineering and relates to a leakage gas gravity trap collection device and method. Background Art

[0002] High-voltage SF6 pipe bus, abbreviated as GIL in English, is a power transmission device. The metal shell adopts a fully welded connection method, and the internal conductor is supported on the shell by supports or pot-type insulators with gas isolation functions, and is filled with 0.2 - 0.8 Mpa of SF6 insulating gas.

[0003] SF6, whose Chinese name is sulfur hexafluoride, is colorless, odorless, and non-toxic itself. However, under certain specific conditions such as in arcs, high temperatures, etc., sulfur hexafluoride may decompose to produce some toxic low fluorides, such as hydrogen fluoride, etc. If personnel inhale these decomposition products, it will cause irritation and harm to the respiratory tract, eyes, etc., and even endanger life in severe cases. Therefore, although GIL is a sealed structure, during long-term operation, due to equipment aging, seal damage, etc., there may be a situation of SF6 gas leakage. If the leaked gas accumulates in an enclosed space, it will cause asphyxiation of personnel when the concentration is too high. Moreover, the density of SF6 gas is about 6 times that of air, and it is easy to accumulate in low-lying areas after leakage. Places such as deep underground power pipe galleries are more likely to have high concentrations of SF6, increasing the safety risk when personnel enter these areas. Therefore, in engineering, GIL must monitor the concentration of SF6 gas to promptly detect leakage situations and take corresponding measures, such as ventilation and air change, to reduce the concentration of leaked gas and ensure the safety of personnel. In addition, SF6 is also a greenhouse gas, and its potential global warming impact is 23,500 times that of carbon dioxide. Although the leakage of SF6 gas in GIL is usually small, in the long run, it will also have a certain impact on the environment.

[0004] For underground power pipe galleries, monitoring and ventilation can reduce the leakage of SF6 gas and reduce the greenhouse effect on the environment. At the same time, during equipment maintenance, repair, etc., properly treating the discharged SF6 gas to avoid direct emission into the atmosphere is also an important measure and requirement that meets environmental protection requirements. However, for long-distance, multi-circuit GIL power pipe galleries in deep underground spaces, due to multi-circuits and long distances, the number of GIL gas chamber units is huge, it is difficult to comprehensively and accurately actively monitor the minute leakage and initial leakage of SF6 gas in GIL. Even if leakage is detected, due to the deep underground long-distance large space, it cannot be discharged in a timely and effective manner. Summary of the Invention

[0005] To solve the problem that the SF6 leakage gas in the deep underground GIL power pipe gallery described in the background technology cannot be discharged in time and effectively, the present invention provides a gravity trap collection device and method for SF6 leakage gas in the deep underground GIL power pipe gallery.

[0006] The device of the present invention is arranged outside the SF6 pipeline busbar. There is a GIL power pipe gallery with a smooth wall surface and no gravity depression settlement area around the SF6 pipeline busbar; a micro-pressure air system for providing longitudinal wind along the GIL power pipe gallery is arranged in the GIL power pipe gallery, and an SF6 gas leakage monitoring mechanism is arranged in the GIL power pipe gallery; a plurality of heavy gas particle traps are arranged at the bottom of the GIL power pipe gallery, and a 0-pressure or slightly negative-pressure SF6 heavy particle collection space is formed inside the heavy gas particle trap through the longitudinal wind of the micro-pressure air system; the bottom of the heavy gas particle trap is connected to a gas recovery mechanism.

[0007] Further, the heavy gas particle trap includes a groove arranged longitudinally along the GIL power pipe gallery.

[0008] Further, the transverse cross-section of the groove is semi-circular. The design of the semi-circular cross-section groove can reduce air flow disturbance and avoid secondary escape of SF6 gas.

[0009] Further, the groove is arranged in a wavy line along the longitudinal direction. The wavy longitudinal layout of the groove can extend the retention path of SF6 gas and improve the collection efficiency.

[0010] Further, the gas recovery mechanism is arranged at intervals along the longitudinal groove of the heavy gas particle trap. The interval gas recovery mechanism can balance the negative pressure distribution in the heavy gas particle trap and ensure continuous recovery.

[0011] Based on the above device, the present invention proposes a gravity trap collection method for SF6 leakage gas in the deep underground GIL power pipe gallery, including:

[0012] When the SF6 gas leakage monitoring mechanism detects SF6 gas leakage in the GIL power pipe gallery, start the micro-pressure air system;

[0013] Accelerate the air gas particles and SF6 gas particles in the GIL power pipe gallery through the longitudinal wind generated by the micro-pressure air system;

[0014] Accelerate the flow velocity of the air gas particles to be greater than the escape velocity v of the heavy gas particle trap r , so that the SF6 gas particles enter the 0-pressure or slightly negative-pressure SF6 heavy particle collection space formed inside the heavy gas particle trap;

[0015] After the SF6 gas particles enter the inside of the heavy gas particle trap and the flow velocity decreases until they lose their flow, recover the SF6 gas through the gas recovery mechanism.

[0016] The escape velocity v of the heavy gas particle trap r is a set value that needs to be between the air velocity and the heavy gas particle velocity accelerated by the longitudinal wind flow.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) High efficiency in SF6 gas collection: Through the synergistic effect of the heavy gas particle trap and the micro-pressure wind system, and by utilizing the characteristic of the large density of SF6 gas, a 0-pressure or micro-negative pressure collection space is formed inside the heavy gas particle trap, significantly improving the capture efficiency of SF6 heavy gas particles and solving the problem that it is difficult to effectively collect SF6 gas in traditional pipe galleries;

[0019] (2) Strong directivity in gas separation and recovery: The longitudinal wind generated by the micro-pressure wind system accelerates the flow of air particles, making their velocity exceed the trap escape velocity, while the SF6 gas particles are separated due to gravity sedimentation and retained inside the heavy gas particle trap, realizing the dynamic separation and directional enrichment recovery of SF6 gas;

[0020] (3) High degree of automation: By combining the linkage control of the SF6 gas leakage monitoring mechanism and the micro-pressure wind system, a closed-loop management of real-time leakage detection - automatic startup - rapid collection is achieved, reducing the need for manual intervention and greatly enhancing the automation of SF6 gas leakage recovery;

[0021] (4) Environmental protection and safety: By actively recovering SF6 gas with a high greenhouse effect potential, greenhouse gas emissions are reduced, and at the same time, potential safety hazards caused by the accumulation of SF6 gas in the pipe gallery are avoided.

[0022] All in all, the present invention utilizes the cross-sectional structure of the smooth and gravity-free depression settlement area of the deep underground GIL power pipe gallery, and by using the characteristic that the density of SF6 gas is much greater than that of air, under the condition of a certain longitudinal ventilation wind speed, the gas in the pipe gallery is actively accelerated and stratified by wind pressure, and the SF6 gas is introduced into the heavy gas particle trap of the SF6 heavy-density gas arranged at the bottom of the pipe gallery after being longitudinally stratified by gentle breeze, achieving the purpose of long-term and safe collection of SF6 leakage gas in the long-distance underground GIL power corridor. The present invention combines the gravity sedimentation principle with fluid dynamics, and through structural optimization and system coordination, realizes the passive capture and active recovery of SF6 heavy gas, and is extremely suitable for the emergency treatment of dangerous heavy gas leakage in restricted spaces such as deep underground pipe galleries. Description of the Drawings

[0023] Figure 1 It is a cross-sectional schematic diagram of the gravity trap collection device.

[0024] Figure 2 It is a longitudinal sectional schematic diagram of the gravity trap collection device.

[0025] Figure 3 It is a bottom-up schematic view of the gravity trap collection device.

[0026] Explanation of reference numerals: 1 - GIL power pipe gallery; 2 - SF6 pipe bus; 3 - micro-pressure air system; 4 - heavy gas particle trap; 5 - gas recovery mechanism. Specific embodiments

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] The SF6 pipe bus 2 is generally a high-voltage SF6 pipe bus (GIL) of 110 kV - 1000 kV, which is a power high-voltage transmission device. It adopts the full-connected welding method of the metal shell, and the internal conductor is supported on the shell by supports or pot-type insulators with gas separation functions. The internal is filled with 0.2 Mpa - 0.8 Mpa of SF6 insulating gas. Among them, the 550 kV high-voltage SF6 pipe bus is usually filled with 0.5 Mpa of SF6 insulating gas.

[0029] As Figure 1 , Figure 2 and Figure 3 shown, the deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device is arranged outside the SF6 pipe bus 2, and a GIL power pipe gallery 1 with a smooth wall surface and no gravity depression settlement area is arranged around the SF6 pipe bus 2. Specifically, the internal structural wall surface of the GIL power pipe gallery 1, the GIL pipe bus and its support structure and other equipment are all smooth, without sharp corners and without depression settlement areas in the gravity direction, that is, at the parts where SF6 gas leakage may occur in the whole gallery, in the still state without wind, the SF6 gas can sink to the bottom of the gallery or the heavy gas particle trap 4 described below.

[0030] A micro-pressure air system 3 for providing longitudinal wind along the GIL power pipe gallery 1 is arranged in the GIL power pipe gallery 1; through and by using the natural ventilation and mechanical ventilation of the micro-pressure air system 3 in the longitudinal direction of the pipe gallery, the acceleration of air and SF6 gas in the above-mentioned GIL power pipe gallery 1 is realized, and the stratification of gases with different masses is realized by using the gravity effect and the wind pressure effect, with different flow velocities, and the SF6 leakage gas is actively guided into the heavy gas particle trap 4 described below.

[0031] An SF6 gas leakage monitoring mechanism is arranged in the GIL power pipe gallery 1.

[0032] At the bottom of the GIL power pipe gallery 1, a plurality of heavy gas particle traps 4 are provided. Inside the heavy gas particle traps 4, a SF6 heavy particle collection space with a pressure of 0 or a slight negative pressure is formed by the longitudinal wind of the micro-pressure air system 3. Specifically, under a certain gentle wind pressure, the velocity of the small-density gas can be greater than the minimum wind speed entering this space, that is, the flow velocity of the small-density air gas is greater than the trap escape velocity v r and it will not enter the trap; while due to the large gas density of SF6 gas, its flow velocity is much smaller than that of air molecules under longitudinal gentle wind. When the SF6 gas molecules are smaller than the minimum escape velocity v of the trap r they will enter this space. After entering this space, the SF6 gas molecules will further decrease their velocity to 0 until they lose their flow due to the 0-pressure and slight negative-pressure environment inside the trap space, and thus completely fall into the inside of the trap.

[0033] The bottom of the heavy gas particle trap 4 is connected to the gas recovery mechanism 5.

[0034] Specifically, as Figure 1 shown, the heavy gas particle trap 4 includes a groove arranged longitudinally along the GIL power pipe gallery 1. More specifically, the transverse cross-section of the groove is semi-circular. More specifically, as Figure 3 shown, the groove is wavy along the longitudinal direction.

[0035] Specifically, as Figure 2 shown, the gas recovery mechanism 5 is arranged at intervals along the longitudinal groove of the heavy gas particle trap 4.

[0036] Based on the above-mentioned device, a method for collecting SF6 leakage gas by gravity trap in a deep underground GIL power pipe gallery is proposed, including:

[0037] When the SF6 gas leakage monitoring mechanism detects that there is SF6 gas leakage in the GIL power pipe gallery 1, the micro-pressure air system 3 is started;

[0038] The longitudinal wind generated by the micro-pressure air system 3 is used to accelerate the air gas particles and SF6 gas particles in the GIL power pipe gallery 1;

[0039] The flow velocity of the air gas particles is accelerated to be greater than the escape velocity v of the heavy gas particle trap 4 r , so that the SF6 gas particles enter the SF6 heavy particle collection space with a pressure of 0 or a slight negative pressure formed inside the heavy gas particle trap 4; among them, the escape velocity v of the heavy gas particle trap r is a set value, and this value needs to be between the velocity values of the air and heavy gas particles accelerated by the longitudinal wind flow;

[0040] After the SF6 gas particles enter the inside of the heavy gas particle trap 4 and their flow velocity decreases until they lose their flow, the SF6 gas is recovered through the gas recovery mechanism 5. Embodiment

[0041] Taking the long-distance transmission of 4 circuits of GIL (divided into three single phases) with a rated voltage of 550 kV and a rated current of 6000 A in a large underground hydropower station as an example. The inner diameter of the underground power pipe gallery is 11 m and the length exceeds 30 km. The single-phase outer shell of the 550 kV GIL is an aluminum pipe with an outer diameter of 500 mm and a thickness of 8 mm. The conductor is a pure aluminum pipe with an outer diameter of 160 mm and a thickness of 15 mm. The internal SF6 pressure is 0.5 Mpa. The length of the GIL is 10 km - 50 km, and all are located in the deep underground power pipe gallery. The GIL is in a three-single-phase split-phase mode and is evenly distributed in the circular cross-section pipe gallery.

[0042] First, a design of an underground power pipe gallery with a smooth wall surface and no gravity depression settlement area is adopted. That is, the internal structural wall surface of the underground GIL power pipe gallery 1, the GIL pipeline bus and its support structure and other equipment are all smooth, without sharp corners and without depression settlement areas in the direction of gravity. That is, in the parts where SF6 gas leakage may occur in the whole corridor, in the still air state, the SF6 gas can sink to the bottom of the corridor. In this embodiment, there are 4 circuits of 500 kV high-voltage SF6 pipeline buses (GIL) and 12 single-phase SF6 pipeline buses, which are high-voltage power transmission equipment. The metal outer shell is welded in full connection. The internal conductor is supported on the outer shell by supports or pot-type insulators with gas separation functions, and is filled with 0.2 Mpa - 0.8 Mpa (usually 0.5 Mpa for 550 kV) of SF6 insulating gas.

[0043] Three heavy gas particle traps 4 are arranged at the bottom of the GIL power pipe gallery 1. The inside of the heavy gas particle trap 4 forms a 0-pressure or slightly negative-pressure SF6 heavy particle collection space through the longitudinal wind of the micro-pressure air system 3. The heavy gas particle trap 4 is a groove arranged longitudinally along the GIL power pipe gallery 1. The transverse cross-section of the groove is semi-circular, and the groove is arranged in a wavy line along the longitudinal direction. A micro-pressure air system 3 for providing longitudinal wind along the GIL power pipe gallery 1 is arranged in the GIL power pipe gallery 1; an SF6 gas leakage monitoring mechanism is arranged in the GIL power pipe gallery 1; the bottom of the heavy gas particle trap 4 is connected to the gas recovery mechanism 5.

[0044] When the micro-pressure air system 3 is started, when there are two gases with different densities in the corridor of the GIL power pipe gallery 1 and there is a certain longitudinal wind speed, these two gases will accelerate separation. That is, the SF6 gas with a larger density will sink, and the air gas with a smaller density will rise. For the gas with a larger density, due to its own tendency to sink and the longitudinal wind speed making it move in the horizontal direction, it will move downward at a certain angle and accelerate along the wind direction, so as to separate from the gas with a smaller density faster. For the gas with a smaller density, its upward tendency plus the action of the longitudinal wind speed will make it move upward at a certain angle and accelerate along the wind direction, and will also accelerate the separation from the gas with a larger density.

[0045] The gas recovery mechanism 5 is used to collect and recover the SF6 gas falling into the heavy gas particle trap 4, and can be a mobile inspection and recovery method, or a permanent pipeline segmented connection to the heavy gas particle trap 4 for centralized recovery.

[0046] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. Deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device, which is arranged outside the SF6 pipeline busbar (2), and is characterized in that: The periphery of the SF6 pipeline busbar (2) is provided with a GIL power pipe gallery (1) with a smooth wall surface and no gravity depression settlement area; a micro-pressure air system (3) for providing longitudinal air along the GIL power pipe gallery (1) is arranged in the GIL power pipe gallery (1), and an SF6 gas leakage monitoring mechanism is arranged in the GIL power pipe gallery (1); a plurality of heavy gas particle traps (4) are arranged at the bottom of the GIL power pipe gallery (1), and an SF6 heavy particle collection space with a pressure of 0 or a slight negative pressure is formed inside the heavy gas particle trap (4) through the longitudinal air of the micro-pressure air system (3); the bottom of the heavy gas particle trap (4) is communicated with a gas recovery mechanism (5).

2. The deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device according to claim 1, characterized in that: The heavy gas particle trap (4) includes a groove arranged longitudinally along the GIL power pipe gallery (1).

3. The deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device according to claim 2, characterized in that: The transverse cross-section of the groove is semi-circular.

4. The deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device according to claim 3, characterized in that: The groove is arranged in a wavy line along the longitudinal direction.

5. The deep underground GIL power pipe gallery SF6 leakage gas gravity trap collection device according to claim 2, characterized in that: The gas recovery mechanism (5) is arranged at intervals along the longitudinal groove of the heavy gas particle trap (4).

6. A method for collecting SF6 leakage gas gravity traps in a deep underground GIL power pipe gallery using the device according to any one of claims 1-5, characterized in that, Including: When the SF6 gas leakage monitoring mechanism detects SF6 gas leakage in the GIL power pipe gallery (1), the micro-pressure air system (3) is started; The longitudinal wind force generated by the micro-pressure air system (3) accelerates the air gas particles and SF6 gas particles in the GIL power pipe gallery (1); Accelerate the flow velocity of air gas particles to be greater than the escape velocity v of the heavy gas particle trap (4), so that SF6 gas particles enter the SF6 heavy particle collection space with zero pressure or slightly negative pressure formed inside the heavy gas particle trap (4); r ​ After the SF6 gas particles enter the inside of the heavy gas particle trap (4) and the flow velocity decreases until the flow stops, the SF6 gas is recovered through the gas recovery mechanism (5).

7. The method for collecting SF6 leakage gas by gravity trap in the deep underground GIL power pipe gallery according to claim 6, characterized in that: The escape velocity v of the heavy gas particle trap r is a set value that needs to be between the velocity values of the air and the heavy gas particles accelerated by the longitudinal wind flow.

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