A multi-medium mixing device and fire protection system for ultra-high voltage converter transformer

Abstract

The present invention provides a multi-medium mixing device for an ultra-high voltage converter transformer, comprising a composite venturi tube and a mixing pipe connected in sequence, wherein the composite venturi tube comprises an inner venturi tube connected to a dry powder pipe and an outer venturi tube connected to a foam pipe, the inner venturi tube is nested in the outer venturi tube, the outer venturi tube is connected to the mixing pipe, and the outlet of the inner venturi tube is located before the outer throat of the outer venturi tube. The present invention also provides a fire fighting system using the mixing device. The advantages of the present invention are that after the ultra-fine dry powder enters the inner venturi tube and passes through the inner throat, the cross-sectional area of ​​the pipe is reduced, thereby accelerating the ultra-fine dry powder, and the ultra-fine dry powder can be accelerated and mixed with the compressed air foam, and then accelerated through the outer throat, promoting uniform mixing of the two media, so that the compressed air foam can effectively wrap the ultra-fine dry powder without the phenomenon of dispersed distribution.

Description

Technical Field

[0001] The present invention relates to the technical field of fire protection facilities for ultra-high voltage power exchange stations, and in particular to a multi-medium mixing device and a fire protection system for ultra-high voltage converter transformers. Background Art

[0002] In long-distance power transmission, UHV DC transmission technology is implemented on a large scale in engineering applications because it has the characteristics of large transmission capacity, long transmission distance and small transmission loss compared with UHV AC transmission technology. However, in UHV transmission, a converter substation is required to convert DC to AC. The construction and operation costs of a converter substation far exceed those of an UHV AC substation with the same voltage level and transmission capacity. During the operation of the converter transformer, hundreds of tons of flammable transformer oil are filled inside. If a fault occurs inside the converter transformer, the converter transformer will physically explode under the action of the fault arc, and the converter transformer oil will also produce a large amount of flammable gas. The flammable gas and converter transformer oil will spray out from the weak parts / gaps of the converter transformer. When the concentration of the sprayed flammable gas and converter transformer oil in the air reaches the explosion limit, a chemical explosion will occur, accompanied by the overflow and combustion of the converter transformer oil, which will cause the fire to spread.

[0003] The foam fire fighting system is the main fire fighting measure currently used in the UHV converter station. It has good cooling capacity and fire prevention ability. However, the instantaneous fire control ability of the foam fire fighting system is relatively limited; the dry powder fire fighting system has a very strong fire control ability, but its single fire prevention ability is relatively insufficient. For this reason, in the prior art, a suspended dry powder ball is set at the UHV converter transformer tap switch and other parts prone to explosion and fire, and a temperature-sensitive glass ball is installed at the nozzle. Under normal circumstances, the upper end of the glass ball supports the sealing plate at the nozzle. When the ambient temperature rises during a fire, the liquid in the glass ball expands due to heat and breaks, and the sealing plate automatically falls off. The dry powder agent in the fire extinguishing device is sprayed out of the nozzle under the action of nitrogen to extinguish the fire. However, when the ordinary suspended dry powder ball explodes due to heat, the splashing ball fragments may damage the foam spray nozzle and cause it to malfunction or even fail.

[0004] The invention patent with publication number CN203971251U discloses a pneumatic dry powder and foam mixed liquid extinguishing device, which extinguishes fire by mixing fire water and foam stock solution in proportion and then mixing with dry powder at the nozzle inlet. However, dry powder has no water repellency and is easily mixed with water or foam at the pipe and nozzle outlet, which makes it impossible to wrap the dry powder with foam, and may even spray muddy or suspended liquid, making it difficult to cope with the various fire modes of UHV converter transformers. The invention patent with publication number CN209392657U provides a suspended dry powder fire extinguishing device linkage pneumatic system, which automatically sprays dry powder to extinguish fire when there is a fire through a starting device, but the amount of suspended dry powder is limited, and the fire may recur during the development process. The use strategy of dry powder and foam needs to be switched in conjunction with the needs of fire control or fire extinguishing. Therefore, this patent is also unable to adapt to the different fire modes of UHV converter transformers. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a multi-media mixing device capable of uniformly wrapping dry powder with foam, and a fire fighting system capable of switching fire extinguishing media according to the fire intensity and having strong fire control and fire extinguishing capabilities.

[0006] The present invention solves the above technical problems through the following technical solutions: a multi-media mixing device for an ultra-high voltage converter transformer, comprising a composite venturi tube and a mixing pipe connected in sequence, the composite venturi tube comprising an inner venturi tube connected to a dry powder pipe and an outer venturi tube connected to a foam pipe, the inner venturi tube is nested in the outer venturi tube, the outer venturi tube is connected to the mixing pipe, and the outlet of the inner venturi tube is located before the outer throat of the outer venturi tube.

[0007] In the present invention, after the ultrafine dry powder enters the inner venturi tube, the cross-sectional area of ​​the tube decreases when passing through the inner throat, thereby accelerating the ultrafine dry powder. The ultrafine dry powder leaving the inner venturi tube can be accelerated to mix with the compressed air foam in the outer venturi tube. The mixed medium is accelerated again after flowing through the outer throat, promoting uniform mixing of the two media, so that the compressed air foam can effectively wrap the ultrafine dry powder without the phenomenon of dispersed distribution, so that the fire-fighting medium can be effectively mixed to extinguish the fire.

[0008] Preferably, the throats of the inner venturi tube and the outer venturi tube are both close to their respective outlets.

[0009] Preferably, a vortex flow channel penetrating along the axial direction is provided in the mixing pipe.

[0010] Preferably, a plurality of vortex flow channels are evenly arranged along the circumference of the mixing pipe.

[0011] Preferably, the dry powder pipeline includes a high-pressure gas generating device and an ultrafine dry powder container which are connected in sequence; the high-pressure gas generating device can provide a high-speed airflow and supply it to the ultrafine dry powder container through a gas pipeline, a flow rate regulating valve is provided on the gas pipeline, an ultrafine dry powder adding pipeline is provided on the ultrafine dry powder container, and a dry powder pipeline electronic valve is provided between the ultrafine dry powder container and the composite venturi tube.

[0012] Preferably, the foam pipeline comprises a compressed air foam generating device, and a compressed air foam pipeline electronic valve is arranged between the compressed air foam generating device and the composite venturi tube.

[0013] Preferably, the dry powder pipeline electronic valve and the compressed air foam pipeline electronic valve can both be remotely controlled and manually operated.

[0014] Preferably, the outlet of the mixing pipe is connected to the main fire-fighting pipe, and the main fire-fighting pipe is provided with a plurality of release nozzles.

[0015] Preferably, the main fire-fighting pipe is nested in the explosion-proof pipe, the release nozzle is connected to the main fire-fighting pipe and exposed on the side of the explosion-proof pipe facing the converter transformer, and the position where the release nozzle is connected to the main fire-fighting pipe is hidden inside the explosion-proof pipe.

[0016] The present invention also provides a fire-fighting system using the multi-media mixing device for ultra-high voltage converter transformers, wherein the inner venturi tube accelerates ultrafine dry powder through a high-pressure gas generating device, and the outer venturi tube generates compressed air foam through a compressed air foam generating device. The fire-fighting system includes an alarm system communicatively connected to the compressed air foam generating device and the high-pressure gas generating device, and the alarm system is communicatively connected to a fire detector. When the fire detector detects the presence of an open flame, the alarm system controls the compressed air foam generating device and the high-pressure gas generating device to work simultaneously. When the fire monitor signal changes from the presence of an open flame to the absence of an open flame, the alarm system shuts down the high-pressure gas generating device, and the compressed air foam generating device keeps working.

[0017] The advantages of the multi-media mixing device and fire fighting system for ultra-high voltage converter transformer provided by the present invention are: after the ultra-fine dry powder enters the inner venturi tube and passes through the inner throat, the cross-sectional area of ​​the pipeline is reduced, thereby accelerating the ultra-fine dry powder, and the ultra-fine dry powder leaving the inner venturi tube can be accelerated and mixed with the compressed air foam in the outer venturi tube, and the mixed medium is accelerated again after flowing through the outer throat, promoting the uniform mixing of the two media, so that the compressed air foam can effectively wrap the ultra-fine dry powder, and there will be no phenomenon of dispersed distribution, so that the fire fighting medium can be effectively mixed and extinguished. The mixing pipeline is provided with a vortex flow channel, which can accelerate the fire fighting medium, improve the mixing effect, and increase the coverage of the nozzle. The high-pressure gas flow rate is adjusted by the high-pressure gas generating device and the flow rate regulating valve, which is convenient to use. The dry powder pipeline electronic valve and the compressed air foam pipeline electronic valve both support remote control operation and manual operation; convenient to use; the fire fighting system can flexibly change the fire fighting medium used according to different fire conditions, so as to carry out fire fighting operations efficiently and safely, and realize the linkage switching of dry powder and foam in fire control and fire fighting operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a multi-medium mixing device for an ultra-high voltage converter transformer provided by an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a composite venturi tube of a multi-medium mixing device for an ultra-high voltage converter transformer provided by an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a mixing pipeline of a multi-medium mixing device for an ultra-high voltage converter transformer provided by an embodiment of the present invention;

[0021] Figure 4 A cross-sectional view of a mixing pipe of a multi-medium mixing device for an ultra-high voltage converter transformer provided by an embodiment of the present invention;

[0022] Figure 5 A schematic diagram of the cooperation between the release nozzle and the main fire fighting pipeline of the multi-medium mixing device for the ultra-high voltage converter transformer provided by one of the embodiments of the present invention;

[0023] Figure 6 A schematic diagram of the cooperation between the release nozzle and the main fire-fighting pipeline of the multi-medium mixing device for the ultra-high voltage converter transformer provided in the second embodiment of the present invention;

[0024] Figure 7 A schematic diagram of the cooperation between the release nozzle and the main fire-fighting pipeline of the multi-medium mixing device for the ultra-high voltage converter transformer provided in the third embodiment of the present invention;

[0025] Figure 8A schematic diagram of the cooperation between the release nozzle and the main fire fighting pipeline of the multi-medium mixing device for the ultra-high voltage converter transformer provided in the fourth embodiment of the present invention;

[0026] Fig. 9 A schematic diagram of a multi-medium combined fire protection system for an ultra-high voltage converter transformer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0028] refer to Figure 1 This embodiment provides a multi-medium mixing device for a UHV converter transformer, comprising a composite venturi tube 1 and a mixing pipe 2 connected in sequence; Figure 2 The composite venturi tube 1 includes an inner venturi tube 11 connected to the dry powder pipeline 3, and an outer venturi tube 12 connected to the foam pipeline 4, the inner venturi tube 11 is nested in the outer venturi tube 12, the outer venturi tube 12 is connected to the mixing pipeline 2, and the outlet of the inner venturi tube 11 is located before the outer throat 121 of the outer venturi tube 12.

[0029] In this embodiment, after the ultrafine dry powder enters the inner venturi tube 11 and passes through the inner throat 111, the cross-sectional area of ​​the pipe is reduced, thereby accelerating the ultrafine dry powder. The ultrafine dry powder leaving the inner venturi tube 11 can be accelerated to mix with the compressed air foam in the outer venturi tube 12. The mixed medium is accelerated again after flowing through the outer throat 121, promoting uniform mixing of the two media, so that the compressed air foam can effectively wrap the ultrafine dry powder, and there will be no dispersed distribution phenomenon, so that the fire-fighting medium can be effectively mixed to extinguish the fire.

[0030] The throats of the inner venturi tube 11 and the outer venturi tube 12 are both arranged close to their respective outlets, so that the firefighting medium will not lose flow velocity in the composite venturi tube 1 after being accelerated through the inner throat 111 and the outer throat 121 .

[0031] Combination Figure 3 and Figure 4 The interior of the mixing pipe 2 has a vortex flow channel 21 that penetrates along the axial direction. The mixed medium of the ultrafine dry powder and the compressed air foam that flows out from the outer throat 121 of the outer venturi tube 12 enters the vortex flow channel 21 and rotates rapidly. The compressed air foam wraps the ultrafine dry powder and flows out of the mixing pipe 2 rapidly to prevent the formation of ultrafine dry powder dispersion. In this embodiment, four vortex flow channels 21 are evenly arranged along the circumferential direction on the mixing pipe 2, so as to ensure the carrying capacity and prevent the medium from accumulating at the entrance of the mixing pipe 2 and affecting the flow rate.

[0032] During the specific connection, the composite venturi tube 1 and the mixing pipe 2 are connected to each other through pipe screw connection, the inner venturi tube 11 is screwed and connected to the dry powder pipe 3; the outer venturi tube 12 is screwed and connected to the foam pipe 4 to release the nozzle.

[0033] Refer to Figure 1 , the dry powder pipeline 3 includes a high-pressure gas generating device 31 and an ultra-fine dry powder container 32 which are connected in sequence; the high-pressure gas generating device 31 can provide a high-speed airflow and supply the ultra-fine dry powder container 32 through a gas pipeline (not shown in the figure), a flow rate regulating valve 33 is provided on the gas pipeline, an ultra-fine dry powder adding pipeline 34 is provided on the ultra-fine dry powder container 32, and a dry powder pipeline electronic valve 36 is provided between the ultra-fine dry powder container 32 and the composite venturi tube 1; in this embodiment, the high-pressure gas generating device 31 can provide a gas flow rate of 10m / s to 200m / s, and the gas flow rate is controlled by the flow rate regulating valve 33, the high-speed gas enters the ultra-fine dry powder container 32, the ultra-fine dry powder enters the ultra-fine dry powder container 32 through the ultra-fine dry powder adding pipeline 34, and then enters the inner venturi tube 11 under the impact of the high-speed airflow, and the high-speed airflow passes through the inner throat 121 and generates a vacuum degree for accelerating the ultra-fine dry powder again, so as to make up for the flow rate loss in the dry powder pipeline 3 and the inner venturi tube 11.

[0034] The foam pipeline 4 includes a compressed air foam generating device 41 , and a compressed air foam pipeline electronic valve 42 is arranged between the compressed air foam generating device 41 and the composite venturi tube 1 ; the compressed air foam generating device 41 generates compressed air foam which then flows to the outer venturi tube 12 .

[0035] The dry powder pipeline electronic valve 36 and the foam pipeline electronic valve 42 are used to control the opening and closing of the corresponding pipelines respectively. In this embodiment, these two electronic valves can be operated by remote control and manual operation, so as to be convenient to use.

[0036] When in use, the outlet of the mixing pipe 2 provided in this embodiment is connected to the main fire-fighting pipe 6 , and a plurality of release nozzles 5 are arranged on the main fire-fighting pipe 6 .

[0037] refer to Figure 5 In order to improve the explosion-proof performance of the main fire-fighting pipe 6, the main fire-fighting pipe 6 is nested inside the explosion-proof pipe 7, the release nozzle 5 is screwed on the main fire-fighting pipe 6, the release nozzle 5 is arranged toward the converter transformer, the end of the release nozzle 5 is outside the explosion-proof pipe 7, and the connection position between the release nozzle 5 and the main fire-fighting pipe 6 is hidden in the explosion-proof pipe 7. In this way, the main fire-fighting pipe 6 is prevented from being damaged in the explosion, and the release nozzle 5 will not be deformed due to high temperature to cope with the envelope of the fire-fighting area.

[0038] refer to Figure 5The explosion-proof pipe 7 is fixed to the firewall and / or concrete foundation beside the converter transformer by screwing, welding or pre-embedded. The explosion-proof pipe 7 has a mounting hole 71 for the nozzle 5 to pass through. The main fire-fighting pipe 6 has a liquid outlet pipe 61 coaxial with the mounting hole 71. The liquid outlet pipe 61 is provided with an internal thread 62. The nozzle 5 has an external thread 51 screwed with the internal thread 62, so that the nozzle 5 can be screwed and fixed inside the explosion-proof pipe 7. When an explosion occurs, the main fire-fighting pipe 6 may collide with the pipe wall inside the explosion-proof pipe 7. In a preferred embodiment, a buffer pad 72 can be provided inside the explosion-proof pipe 7 for buffering protection. The buffer pad 72 can be provided inside the explosion-proof pipe 7 or outside the main fire-fighting pipe 6. For the convenience of operation, it is generally directly attached to the outside of the main fire-fighting pipe 6. At least the buffer pad 72 is provided on the side of the main fire-fighting pipe 6 facing away from the converter transformer.

[0039] The nozzle 5 includes a dome-shaped release cone 52 and a fixed pipe 53 fixedly connected to the release cone 52. The side of the release cone 52 connected to the fixed pipe 53 is a flat bottom surface. The external thread 51 is arranged on the fixed pipe 53. The surface of the release cone 52 has a release hole 54. The aperture and the number of openings of the release hole 54 are determined according to the fire extinguishing range and coverage range of the UHV converter transformer. In this embodiment, the sum of the areas of the release holes 54 is not less than the cross-sectional area of ​​the fixed pipe 53, and the diameter of the release hole 54 is 3 to 10 mm. The fire-fighting medium is sprayed out through the arc surface of the release cone 52 to extinguish the target area. The fire-fighting medium is released evenly to form a single-point multi-directional coverage, which is beneficial to improve the adaptability of the UHV converter transformer in the event of an explosion fire.

[0040] A flat gasket (not shown) and a spring gasket (not shown) are provided between the flat bottom surface of the release cone 52 and the explosion-proof tube 7, so as to improve the axial stability of the nozzle 5 and prevent shaking during explosion. Moreover, since the spring gasket is in a compressed state, it can provide axial stabilizing force when disassembling the nozzle 5, which is convenient for maintenance and replacement.

[0041] refer to Figure 6 A mounting seat (not shown) may also be fixed on the side of the mounting hole 71 facing the converter transformer, and the mounting seat is fixedly matched with the liquid outlet pipe 61, thereby fixing the liquid outlet pipe 61 and improving the stability of the main fire-fighting pipe 6. The mounting seat includes a fixing plate 81 fixedly matched with the outer pipe wall of the explosion-proof pipe 7, and the fixing plate 81 has a through hole (not shown) for allowing the nozzle 5 to pass through. The fixing plate 81 is fixedly matched with the liquid outlet pipe 61, thereby auxiliary fixing the liquid outlet pipe 61 and improving the stability of the main fire-fighting pipe 6. The shape of the fixing plate 81 is adaptively matched with the explosion-proof pipe 7. In this embodiment, the fixing plate 81 is directly welded or screwed to the end of the liquid outlet pipe 61. At this time, the shaking amplitude of the main fire-fighting pipe 6 is limited, and the buffer pad 72 for protecting the main fire-fighting pipe 6 can be cancelled.

[0042] refer to Figure 7 In this embodiment, the end of the liquid outlet pipe 61 extends outside the explosion-proof pipe 7, the diameter of the through hole on the fixed plate 81 is larger than the diameter of the liquid outlet pipe 61, and the end of the fixed plate 81 is provided with a first transition plate 82 fixedly connected to the end of the liquid outlet pipe 61, the first transition plate 82 and the fixed plate 81 are integrally formed or welded, and the first transition plate 82 is welded or screwed to the liquid outlet pipe 61. The angle between the first transition plate 82 and the fixed plate 81 is an obtuse angle, and the angle between the first transition plate 82 and the axial direction of the liquid outlet pipe 61 is an acute angle.

[0043] When the nozzle 5 is subjected to an axial explosion impact force, part of the pressure can be released through the deformation of the first transition plate 82 to prevent the nozzle 5 from being damaged.

[0044] for Figure 6 and Figure 7 For the scheme shown, since the end of the liquid outlet pipe 61 is eventually flush with or extends out of the explosion-proof pipe 7, the diameter of the explosion-proof pipe 7 needs to be larger than the main fire-fighting pipe 6 to ensure that the main fire-fighting pipe 6 with the liquid outlet pipe 61 fixed can move axially in the explosion-proof pipe 7 for nesting and matching. At the same time, after the main fire-fighting pipe 6 and the explosion-proof pipe 7 are in place, the main fire-fighting pipe 6 can be radially adjusted to allow the liquid outlet pipe 61 to extend out of the mounting hole 71.

[0045] refer to Figure 8 The mounting seat also includes an annular connecting plate 83 fixedly matched with the outer tube wall of the liquid outlet pipe 61 , the axial direction of the connecting plate 83 is parallel to the axial direction of the liquid outlet pipe 61 , and the connecting plate 83 is fixedly matched with the fixing plate 81 .

[0046] When in use, the main fire-fighting pipe 6 is sleeved into the explosion-proof pipe 7, the liquid outlet pipe 61 is aligned with the mounting hole 71, and then the mounting seat is clamped in the mounting hole 71. The fixing plate 81 can be fixedly connected to the explosion-proof pipe 7 by welding or screwing. The connecting plate 83 can also be fixedly connected to the liquid outlet pipe 61 by welding or screwing. However, when welding, only one end close to the converter transformer can be welded. It is preferred to use bolts (not shown) to radially connect the liquid outlet pipe 61 and the connecting plate 83 inside the liquid outlet pipe 61. The end of the bolt can be hidden under the pipe wall of the liquid outlet pipe 61, and it can be fixed using tools such as a socket and a wrench; in this way, multiple positions can be fixed along the axial direction.

[0047] The fixing plate 81 and the connecting plate 83 are perpendicular to each other. When the fixing plate 81 and the connecting plate 83 are directly connected, the nozzle 5 and Figure 6 and Figure 7 The same, the matching state between the liquid outlet pipe 61 and the mounting seat after installation is the same as Figure 6 and 7 About the same.

[0048] In this embodiment, a second transition plate 84 is further provided to connect the fixed plate 81 and the connecting plate 83. The second transition plate 84 is tilted toward the inside of the explosion-proof tube 7. At this time, the side of the release cone 52 connected to the fixed tube 53 is tilted to the second transition plate 84 to adapt to the cooperation. After fixation, in addition to the spring gasket, the second transition plate 84 can also wrap the nozzle 5 to improve the fixing effect of the nozzle 5 and protect the nozzle 5.

[0049] refer to Fig. 9 This embodiment further provides a multi-media combined fire protection system using the multi-media mixing device, including an alarm system that is communicatively connected to the compressed air foam generating device 41 and the high-pressure gas generating device 31. The alarm system is communicatively connected to a fire detector. When the fire detector detects the presence of an open flame, the alarm system controls the compressed air foam generating device 41 and the high-pressure gas generating device 31 to work simultaneously, and uses a mixed fire protection medium to extinguish the fire. When the open flame is extinguished, that is, when the fire monitor signal changes from the presence of an open flame to the absence of an open flame, the alarm system turns off the high-pressure gas generating device 31, and only uses the compressed air foam generating device 41 to spray compressed air foam to prevent the flame from reigniting. The compressed air foam generating device 41 is set to shut down and stop working after working for a period of time, or it can be manually shut down by the operator. The fire detector can be purchased directly, and a point-type ultraviolet flame detector, a point-type infrared flame detector, etc. can be used. The embodiment uses a dual-wavelength red-ultraviolet composite flame detector of the Yijie A710 / UVIR2 model.

[0050] Based on the above fire-fighting system, the present application can flexibly change the fire-fighting medium used according to different fire conditions, thereby performing fire-fighting operations efficiently and safely, and realizing the coordinated switching of dry powder and foam in fire control and fire extinguishing operations.

Claims

1. A multi-medium mixing device for ultra-high voltage converter transformer, characterized in that: It comprises a composite venturi tube and a mixing pipe connected in sequence, wherein the composite venturi tube comprises an inner venturi tube connected to a dry powder pipe and an outer venturi tube connected to a foam pipe, the inner venturi tube is nested in the outer venturi tube, the outer venturi tube is connected to the mixing pipe, and the outlet of the inner venturi tube is located before the outer throat of the outer venturi tube; the mixing pipe is provided with a vortex flow channel which runs through in the axial direction, the outlet of the mixing pipe is connected to a main fire-fighting pipe, and a plurality of release nozzles are provided on the main fire-fighting pipe.

2. The multi-medium mixing device for a UHV converter transformer according to claim 1, characterized in that: The throats of the inner venturi tube and the outer venturi tube are both close to their respective outlets.

3. The multi-medium mixing device for ultra-high voltage converter transformer according to claim 1, characterized in that: Four vortex flow channels are evenly arranged along the circumference of the mixing pipeline.

4. The multi-medium mixing device for a UHV converter transformer according to claim 1, characterized in that: The dry powder pipeline includes a high-pressure gas generating device and an ultra-fine dry powder container which are connected in sequence; the high-pressure gas generating device can provide a high-speed airflow and supply it to the ultra-fine dry powder container through a gas pipeline, a flow rate regulating valve is arranged on the gas pipeline, an ultra-fine dry powder adding pipeline is arranged on the ultra-fine dry powder container, and a dry powder pipeline electronic valve is arranged between the ultra-fine dry powder container and the composite venturi tube.

5. The multi-medium mixing device for ultra-high voltage converter transformer according to claim 2, characterized in that: The dry powder pipeline includes a high-pressure gas generating device and an ultra-fine dry powder container which are connected in sequence; the high-pressure gas generating device can provide a high-speed airflow and supply it to the ultra-fine dry powder container through a gas pipeline, a flow rate regulating valve is arranged on the gas pipeline, an ultra-fine dry powder adding pipeline is arranged on the ultra-fine dry powder container, and a dry powder pipeline electronic valve is arranged between the ultra-fine dry powder container and the composite venturi tube.

6. The multi-medium mixing device for a UHV converter transformer according to claim 4, characterized in that: The foam pipeline comprises a compressed air foam generating device, and a compressed air foam pipeline electronic valve is arranged between the compressed air foam generating device and the composite venturi tube.

7. The multi-medium mixing device for a UHV converter transformer according to claim 6, characterized in that: The dry powder pipeline electronic valve can be remotely operated and manually operated.

8. The multi-medium mixing device for an ultra-high voltage converter transformer according to claim 6, characterized in that: The electronic valves of the compressed air foam pipeline can be operated remotely and manually.

9. The multi-medium mixing device for an ultra-high voltage converter transformer according to claim 1, characterized in that: The main fire-fighting pipeline is nested in the explosion-proof pipe, the release nozzle is connected to the main fire-fighting pipeline and exposed on the side of the explosion-proof pipe facing the converter transformer, and the position where the release nozzle is connected to the main fire-fighting pipeline is hidden in the explosion-proof pipe.

10. The fire protection system of the multi-medium mixing device for the UHV converter transformer according to any one of claims 1 to 9, characterized in that: The inner venturi tube accelerates the ultrafine dry powder through the high-pressure gas generating device, and the outer venturi tube generates compressed air foam through the compressed air foam generating device. The fire protection system includes an alarm system that is communicatively connected to the compressed air foam generating device and the high-pressure gas generating device. The alarm system is communicatively connected to a fire detector. When the fire detector detects the presence of an open flame, the alarm system controls the compressed air foam generating device and the high-pressure gas generating device to work simultaneously. When the fire monitor signal changes from the presence of an open flame to the absence of an open flame, the alarm system shuts down the high-pressure gas generating device, and the compressed air foam generating device keeps working.

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