A method for calculating pressure loss in long-distance transportation of compressed air foam suitable for ultra-high voltage stations

Abstract

This invention discloses a method for calculating the pressure loss of long-distance compressed air foam transportation, applicable to ultra-high voltage stations. This method relates to the field of compressed air foam fire extinguishing. The method comprises a main pipeline, branch pipelines, extension pipelines, and a discharge hole. Multiple branch pipelines and multiple extension pipelines are connected to the main pipeline, forming a multi-layered spray pipeline structure between a firewall and a transformer. Discharge holes are provided on each of the main pipeline, branch pipelines, and extension pipelines. The advantages of this invention are that it effectively increases the spray range and coverage area, ensuring uniform and efficient distribution of compressed air foam within the protected area, and achieving good coverage.

Description

Technical Field

[0001] The present invention relates to the field of compressed air foam fire extinguishing, and in particular to a method for calculating the pressure loss of compressed air foam during long-distance transportation, which is applicable to ultra-high voltage stations. Background Art

[0002] The compressed air foam fire extinguishing system is a foam fire extinguishing system based on positive pressure foam production. Its foam is uniform and fine, highly stable, highly effective in extinguishing fires, and has excellent resistance to burning and re-ignition. It also possesses unique technical advantages such as resistance to explosion shock, high temperature, and smoke. It can effectively meet the fire prevention and control needs of UHV converter stations and represents a major technological revolution in the field of fixed fire extinguishing technology. The terminal release device is a key component of the compressed air foam fire extinguishing system, distributing foam. It typically includes a compressed air foam spray pipe, a compressed air foam gun, and a compressed air foam cannon. The compressed air foam spray pipe offers excellent coverage, high flexibility, and the ability to conserve fire extinguishing agents, making it particularly advantageous for responding to small and medium-sized fires.

[0003] However, large oil-filled substation equipment, with its high voltage, high energy, and extensive oil storage capacity, is extremely challenging to extinguish after an explosion or fire. Main transformers, in particular, differ significantly from converter transformers and other conventional oil-immersed transformers in layout, structural characteristics, volume, and site conditions, making fire scenarios more severe and complex. Existing full-scale, real-scale water spray fire extinguishing tests have shown that existing fire extinguishing systems are highly susceptible to damage from high-temperature flames and explosions, reducing or even completely eliminating their firefighting capabilities and failing to meet the actual needs of substation firefighting.

[0004] Patent document CN114100044A discloses a sprinkler system for a compressed air foam fire extinguishing system, comprising a main protective pipe with locally reinforced pipes and branch pipes. Existing compressed air foam sprinkler pipes are arranged along the plane of the fire wall, resulting in a small spray range and coverage area, and poor coverage. This makes it difficult to meet the requirements of substations with large fire walls spanning large oil-filled equipment and asymmetrical arrangements between the main transformer and the fire walls. Existing compressed air foam sprinkler pipes also struggle to ensure that water pressure meets predetermined standards throughout the system. Furthermore, these pipes are installed on the fire wall via spaced-apart support brackets, resulting in poor resistance to high temperatures and explosion shocks. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to improve the covering effect of compressed air foam and ensure that the water pressure at various locations in the system meets predetermined standards.

[0006] The present invention solves the above-mentioned technical problems through the following technical means: a method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations, wherein a compressed air foam spray pipe includes a main pipe, a branch pipe, an extension pipe, and a release hole; a plurality of branch pipes and a plurality of extension pipes are respectively connected to the main pipe, and the main pipe, branch pipes, and extension pipes form a multi-layer spray pipe structure layered along the distance direction between the firewall and the transformer equipment; the main pipe, branch pipes, and extension pipes are all provided with a release hole;

[0007] The method for calculating the pressure loss of compressed air foam long-distance transmission applicable to UHV stations includes the following steps:

[0008] Step 1: Use the formula Obtain the resistance loss H along the way y , where g is the acceleration due to gravity, d is the pipe diameter, and C w is the William roughness coefficient, q is the flow rate, l is the pipe length, ρ is the fluid density, and u is the flow velocity;

[0009] Step 2: Obtain the local resistance loss H through the following steps j :

[0010] Step 2.1: By formula Obtain the local loss coefficient ξ of the elbow W , where d w is the diameter of the elbow, r w is the centerline diameter of the elbow, θ is the bending angle of the elbow;

[0011] Step 2.2: By formula Get the local loss coefficient ξ of the nozzle P , where A0 is the diameter of the pipe where the nozzle is located, A1 is the diameter of the nozzle connection part after the sudden contraction, and A2 is the diameter of the nozzle discharge part;

[0012] Step 2.3: Obtain the local loss coefficient ξ of the tee and gate valve T ,ξ Z ;

[0013] Step 2.4: By formula Get the local resistance loss H j , where ρ is the fluid density and u is the flow velocity;

[0014] Step 3: Use formula H g =ρgh to obtain the potential loss H g , where ρ is the fluid density, g is the acceleration due to gravity, and h is the height difference;

[0015] Step 4: Obtain the total hydraulic pressure loss H based on the sum of the along-line resistance loss, local resistance loss, and position difference loss f, the total hydraulic pressure loss calculation formula is:

[0016] H f =H y +H j +H g ;

[0017] Step 5: Monitor and calculate the total hydraulic pressure loss at each sprinkler in real time, and adjust the pressure at the water supply point if insufficient pressure is found.

[0018] The present invention effectively improves the range and coverage area of ​​the spray by designing a multi-layer spray pipe structure, ensures that the compressed air foam is evenly and efficiently distributed in the protection area, has a good coverage effect, and meets the use requirements under the conditions of large spans of the firewalls on both sides of the large oil-filled equipment in the substation and asymmetric arrangement of the main transformer and the firewalls on both sides; based on the relative position with the water supply outlet point, the pressure loss of each point in the system is quickly calculated, so as to quantify the loss in the energy transfer process; through real-time monitoring and calculation of the total hydraulic pressure loss at each nozzle, the situation of insufficient pressure can be discovered in time, and when insufficient pressure is discovered, the pressure at the water supply point is adjusted to ensure that the performance requirements of the system under working conditions are met and that the water pressure at each point of the system meets the predetermined standards.

[0019] As an optimized technical solution, the main pipeline and the branch pipeline are located on the same layer and are fixedly connected to the firewall respectively. The extension pipeline is located between the main pipeline and the transformer equipment. Multiple extension pipelines form one or more layers.

[0020] As an optimized technical solution, the compressed air foam sprinkler pipe also includes channel steel. The main and branch pipes are both placed within the channel steel, which is installed close to the fire wall. The channel steel wraps around the pipes at an angle of 150 to 180 degrees. The wall thickness of the extension pipe is greater than that of the main and branch pipes, and the extension pipe is fixedly connected to the fire wall via a bracket. The main and branch pipes are placed within the channel steel, and the wall thickness of the extension pipe is greater than that of the main and branch pipes. This improves the sprinkler pipe's resistance to high temperatures and explosion shock, ensuring that the fire extinguishing system can function properly before and after a casing explosion or fire.

[0021] As an optimized technical solution, the compressed air foam spray pipe also includes a first connecting pipe and a second connecting pipe. The main pipe is connected to the branch pipe via the first connecting pipe, and the first connecting pipe is connected to the extension pipe via the second connecting pipe. Both the first connecting pipe and the second connecting pipe have a multi-way structure. The length of the branch pipe and the extension pipe can be adjusted according to different working conditions to achieve rapid fire extinguishing.

[0022] As an optimized technical solution, the compressed air foam spray pipe also includes interface flanges and sealing gaskets. The interfaces between the main, branch, and extension pipes and the connecting pipes are each equipped with two interface flanges, with a sealing gasket positioned between them. The interface flanges are adjustable in angle and made of high-temperature-resistant material. The angles of the branch and extension pipes can be adjusted to suit different operating conditions, enabling rapid fire extinguishing.

[0023] As an optimized technical solution, the compressed air foam spray pipe also includes a diversion pipe and a foam generating device, and the foam generating device is connected to the main pipes on both sides through the diversion pipe.

[0024] As an optimized technical solution, the compressed air foam spray pipe further includes an end plugging piece, and the open ends of the main pipe, branch pipe and extension pipe are all provided with plugging pieces.

[0025] As an optimized technical solution, the main, branch, and extension pipes are all horizontally arranged. The main pipe is installed at least 0.5 meters above the surface of the oil filling equipment, the branch pipes are installed above the top surface of the key protection areas of the oil filling equipment, and the extension pipes are installed at least 0.5 meters above the top surface of the key protection areas of the oil filling equipment. The main span of the UHV converter station oil filling equipment is large. To ensure better foam coverage, multiple streams of foam are required to spray the equipment body. The height of the main, branch, and extension pipes is conducive to spray coverage.

[0026] As an optimized technical solution, the discharge holes are arranged in three rows on the pipe surface: upper, middle, and lower. The holes in each row are evenly distributed, and the diameter of the holes in the middle row is larger than those in the upper and lower rows. This can protect key areas of the oil-filled equipment.

[0027] As an optimized technical solution, the main pipeline, branch pipelines and extension pipelines are all made by 3D printing.

[0028] The advantages of the present invention are:

[0029] 1. The present invention effectively improves the range and coverage area of ​​the spray by designing a multi-layer spray pipe structure, ensuring that the compressed air foam is evenly and efficiently distributed in the protection area, with good coverage effect, and meeting the use requirements under the conditions of large spans of firewalls on both sides of large oil-filled equipment in substations and asymmetric arrangement of the main transformer and the firewalls on both sides; based on the relative position with the water supply outlet point, the pressure loss of each point in the system is quickly calculated, thereby quantifying the loss in the energy transfer process; by real-time monitoring and calculation of the total hydraulic pressure loss at each nozzle, insufficient pressure can be discovered in time, and when insufficient pressure is discovered, the pressure at the water supply point is adjusted to ensure that the performance requirements of the system under working conditions are met and that the water pressure at each point in the system meets the predetermined standards.

[0030] 2. The main pipeline and branch pipeline are arranged in the channel steel, and the wall thickness of the extended pipeline is greater than that of the main pipeline and branch pipeline, which improves the high temperature resistance and explosion impact resistance of the sprinkler pipe and ensures that the fire extinguishing system can work normally before and after the casing explosion and fire.

[0031] 3. The length and angle of branch pipes and extension pipes can be changed according to different working conditions to achieve the purpose of rapid fire extinguishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is an axonometric schematic diagram of a compressed air foam spray pipe according to an embodiment of the present invention.

[0033] Figure 2 This is an axonometric schematic diagram of a compressed air foam spray pipe installed on a firewall according to an embodiment of the present invention.

[0034] Figure 3 It is a cross-sectional schematic diagram of the main pipeline and channel steel according to an embodiment of the present invention.

[0035] Figure 4 It is a partial cross-sectional schematic diagram of the first connecting pipe in an embodiment of the present invention.

[0036] Figure 5 Schematic diagram of delivery holes of different sizes and shapes according to an embodiment of the present invention.

[0037] Figure 6 It is a schematic diagram of the distribution of the release holes on the main pipeline according to an embodiment of the present invention.

[0038] Figure 7 The present invention is a program diagram of a method for calculating the pressure loss of compressed air foam in long-distance transportation applicable to ultra-high voltage stations.

[0039] Figure 8 It is a calculation diagram of a method for calculating the pressure loss of compressed air foam long-distance transportation applicable to ultra-high voltage stations according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0041] An embodiment of the present invention discloses a method for calculating the pressure loss of compressed air foam during long-distance transportation, which is applicable to ultra-high voltage stations.

[0042] like Figures 1 to 4As shown, the compressed air foam spray pipe includes a main pipe 1, a branch pipe 2, an extension pipe 3, a release hole 4, a first connecting pipe 5, a second connecting pipe 6, an interface flange 7, a sealing gasket 8, a channel steel 9, a diversion pipe 10, a foam generating device 11 and an end sealing piece 12.

[0043] The main pipeline 1, branch pipeline 2 and extension pipeline 3 are all made by 3D printing, and multiple branch pipelines 2 and multiple extension pipelines 3 are respectively connected to the main pipeline 1; the main pipeline 1, branch pipeline 2 and extension pipeline 3 form a multi-layer spray pipeline structure layered along the distance direction between the firewall 14 and the transformer equipment 13. The main pipeline 1 and the branch pipeline 2 are located on the same layer and are respectively fixedly connected to the firewall 14. The extension pipeline 3 is located between the main pipeline 1 and the transformer equipment 13. Multiple extension pipelines 3 form one or more layers according to the actual environment of the substation site; the main pipeline 1, branch pipeline 2 and extension pipeline 3 are all provided with a release hole 4.

[0044] The main pipeline 1, branch pipeline 2 and extension pipeline 3 are all arranged horizontally. The installation height of the main pipeline 1 is more than 0.5m higher than the surface of the main body of the oil filling equipment, the installation height of the branch pipeline 2 is slightly higher than the upper surface of the key protection part of the oil filling equipment, and the installation height of the extension pipeline 3 is more than 0.5m higher than the upper surface of the key protection part of the oil filling equipment. It should be noted that the main body span of the UHV converter station oil filling equipment is large. In order to ensure better coverage of the foam, multiple streams of foam need to be sprayed onto the main body of the equipment. The heights of the main pipeline 1, branch pipeline 2 and extension pipeline 3 are the optimal values ​​obtained from the test. Below this height, it is not conducive to the coverage of the spray.

[0045] The main pipe 1 is connected to the branch pipe 2 through the first connecting pipe 5, and the first connecting pipe 5 is connected to the extension pipe 3 through the second connecting pipe 6. The first connecting pipe 5 and the second connecting pipe 6 are both multi-way structures. The branch pipe 2 and the extension pipe 3 can change their lengths according to different working conditions to achieve the purpose of rapid fire extinguishing.

[0046] Two interface flanges 7 are provided at the interfaces between the main pipeline 1, branch pipeline 2 and extension pipeline 3 and the connecting pipeline, and a sealing gasket 8 is provided between the two interface flanges 7; the interface flange 7 adopts a flanging ring plate loose sleeve steel pipe flange, and the implementation standard is GB / T9122. This type of flange can adjust the angle to ensure that the pipeline can be adjusted at any angle; the sealing gasket 8 is made of high-temperature resistant materials such as stainless steel to ensure good sealing effect at high temperatures.

[0047] The main pipe 1 and the branch pipe 2 are both arranged in the channel steel 9 installed horizontally close to the fire wall 14. The wrapping angle of the channel steel 9 to the pipe is 150~180°. The wall thickness of the extension pipe 3 is greater than that of the main pipe 1 and the branch pipe 2. The extension pipe 3 is fixedly connected to the fire wall 14 through a bracket. The above method improves the high temperature resistance and explosion impact resistance of the sprinkler pipe, ensuring that the fire extinguishing system can work normally before and after the casing explosion and fire.

[0048] The foam generating device 11 is connected to the main pipes 1 on both sides through the branch pipe 10. The compressed air foam generated by the foam generating device 11 enters the main pipe 1 through the branch pipe 10 and is then transported from the main pipe 1 to the branch pipe 2 and the extension pipe 3.

[0049] The open ends of the main pipeline 1, the branch pipeline 2 and the extension pipeline 3 are all provided with a blocking member 12. The blocking member 12 can be a pipe cap, a sealing plate or a flange cover to block the pipeline.

[0050] like Figure 5 As shown, the delivery hole 4 can be of various sizes, and the hole shape can be circular, oval, rectangular, diamond, triangular or other shapes.

[0051] like Figure 6 As shown, the release holes 4 are arranged in three rows on the surface of the pipeline, namely, upper, middle and lower rows. The release holes 4 in the same row are evenly distributed, the spacing between adjacent rows of release holes 4 is 20mm to 200mm, the angle between adjacent rows of release holes 4 is 0 to 35°, the apertures of the upper and lower rows of release holes 4 are 5mm to 15mm, and the aperture of the middle row of release holes 4 is 15mm to 25mm. The larger aperture of the middle row of release holes 4 is to protect key areas of the oil-filled equipment.

[0052] like Figure 7 、 Figure 8 As shown in FIG, the method for calculating the pressure loss of compressed air foam long-distance transmission applicable to UHV stations includes the following steps:

[0053] Step 1: When the fluid passes through the straight pipe section, the friction between the fluid and the pipe wall causes energy loss. This energy loss is defined as the resistance loss along the way. Obtain the resistance loss H along the way y , where g is the acceleration due to gravity, d is the pipe diameter, and C w is the William roughness coefficient, q is the flow rate, l is the pipe length, ρ is the fluid density, and u is the flow velocity.

[0054] Step 2: When the fluid passes through local obstacles such as bends, expansion sections, contraction sections, and various valves, the fluid will encounter local obstructions, resulting in changes in flow rate and flow state, which in turn causes energy loss. This energy loss is defined as local resistance loss. The local resistance loss H is obtained through the following steps: j :

[0055] Step 2.1: By formula Obtain the local loss coefficient ξ of the elbow W , where d w is the diameter of the elbow, r w is the centerline diameter of the elbow, and θ is the bending angle of the elbow.

[0056] Step 2.2: By formula Get the local loss coefficient ξ of the nozzle P , where A0 is the pipe diameter where the nozzle is located, A1 is the pipe diameter of the nozzle connection part after the sudden contraction, and A2 is the pipe diameter of the nozzle discharge part.

[0057] Step 2.3: Refer to Table 1 and Table 2 to obtain the local loss coefficient ξ of the tee and gate valve T ,ξ Z .

[0058] Table 1. Local loss coefficient ξ of T-shaped tee T

[0059]

[0060] Table 2. Local resistance coefficient ξ of valve port Z

[0061]

[0062] Step 2.4: By formula Get the local resistance loss H j , where ρ is the fluid density and u is the flow velocity.

[0063] Step 3: When the fluid flows in the pipeline system and the pipeline height changes, the difference in gravitational potential energy will cause the fluid pressure to change, resulting in energy loss. This pressure loss is called potential loss or height loss. It can be expressed by the formula H g =ρgh to obtain the potential loss H g , where ρ is the fluid density, g is the acceleration due to gravity, and h is the height difference.

[0064] Step 4: Obtain the total hydraulic pressure loss H based on the sum of the along-line resistance loss, local resistance loss, and position difference loss f , quantifying the loss during energy transfer.

[0065] The total hydraulic pressure loss calculation formula is:

[0066] H f =H y +H j +H g

[0067]

[0068] Step 5: Real-time monitoring and calculation of the total hydraulic pressure loss at each nozzle can promptly detect insufficient pressure. When insufficient pressure is found, the pressure at the water supply point is adjusted to ensure that the performance requirements of the system under working conditions are met.

[0069] The following describes the working process of the method embodiment of the present invention through a specific example: Assuming that the flow rate of the foam generating device 11 is 0.033m 3 / s, the pipe material is assumed to be new cast iron pipe C w =130, the fluid in the pipe is water, with a density of 1000 kg / m 3 The lengths of the branch pipe 10, the main pipe 1, the first connecting pipe 5 and the second connecting pipe 6 are 4m, 6m, 4m and 2m respectively, the length of the extension pipe 3 is 2m, the height difference between the extension pipe 3 and the outlet of the foam generating device 11 is 6m, the diameter of all pipes is 0.1m, and the radius of the centerline of the elbow is r w The length is 0.05m, the number of elbows is 2, the bending angle of the elbow is 90°, and the positions of the tee pipe, spray pipe, etc. are as follows: Figure 2-6 As shown, there are four nozzles with a diameter of 10 mm. Assuming that the distance between the nozzles on the pipeline 3 is 0.5 m, the pressure loss at the most unfavorable position of the device can be calculated by referring to the pressure loss calculation function, which is the nozzle position at the farthest end of the pipeline 3.

[0070] By formula Calculate the resistance loss H along the way y It is 30275Pa.

[0071] By formula Calculate the local resistance loss H j It is 32534Pa.

[0072] By formula H g =ρgh, calculate the potential loss H g It is 58860Pa.

[0073] In summary, through formula H f =H y +H j +H g Calculate the total hydraulic pressure loss H f It is 121669pa.

[0074] The present invention is aimed at the pipeline layout of the foam spray system. Since its layout method may change in different scenarios, the configuration of the water supply pipeline of the spray pipeline may change. Such changes may include changes in pipeline length, diameter, material, and connection method, all of which may affect the water supply pressure of the system. In order to ensure that the water supply pressure meets the requirements of system operation, the present invention proposes a pressure calculation method for quickly calculating the pressure loss at each nozzle position. This method is based on the principles of fluid mechanics and takes into account factors such as along-the-line resistance loss, local resistance loss, and position difference loss. It can accurately evaluate the water pressure of the system under different working conditions. By real-time monitoring and calculation of the pressure loss at each nozzle, insufficient pressure can be discovered in time, and the pressure at the water supply can be adjusted to ensure that the performance requirements of the system under working conditions are met. The implementation of this method not only improves the stability and reliability of the system, but also helps to reduce energy consumption and maintenance costs, and improves the overall efficiency and economic benefits of the foam spray system.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations, characterized by: The compressed air foam spray pipe includes a main pipe, branch pipes, extension pipes and a discharge hole; a plurality of branch pipes and a plurality of extension pipes are respectively connected to the main pipe, and the main pipe, branch pipes and extension pipes form a multi-layer spray pipe structure layered along the distance direction between the firewall and the transformer equipment; the main pipe, branch pipes and extension pipes are all provided with a discharge hole; The method for calculating the pressure loss of compressed air foam long-distance transmission applicable to UHV stations includes the following steps: Step 1: Use the formula Obtain the resistance loss H along the way y , where g is the acceleration due to gravity, d is the pipe diameter, and C w is the William roughness coefficient, q is the flow rate, l is the pipe length, ρ is the fluid density, and u is the flow velocity; Step 2: Obtain the local resistance loss H through the following steps j : Step 2.1: By formula Obtain the local loss coefficient ξ of the elbow W , where d w is the diameter of the elbow, r w is the centerline diameter of the elbow, θ is the bending angle of the elbow; Step 2.2: By formula Get the local loss coefficient ξ of the nozzle P , where A0 is the diameter of the pipe where the nozzle is located, A1 is the diameter of the nozzle connection part after the sudden contraction, and A2 is the diameter of the nozzle discharge part; Step 2.3: Obtain the local loss coefficient ξ of the tee and gate valve T ,ξ Z ; Step 2.4: By formula Get the local resistance loss H j , where ρ is the fluid density and u is the flow velocity; Step 3: Use formula H g =ρgh to obtain the potential loss H g , where ρ is the fluid density, g is the acceleration due to gravity, and h is the height difference; Step 4: Obtain the total hydraulic pressure loss H based on the sum of the along-line resistance loss, local resistance loss, and position difference loss f , the total hydraulic pressure loss calculation formula is: H f =H y +H j +H g ; Step 5: Monitor and calculate the total hydraulic pressure loss at each sprinkler in real time, and adjust the pressure at the water supply point if insufficient pressure is found.

2. The method for calculating the pressure loss of compressed air foam for long-distance transportation applicable to UHV stations according to claim 1 is characterized in that: The main pipeline and the branch pipeline are located on the same layer and are respectively fixedly connected to the firewall. The extension pipeline is located between the main pipeline and the transformer equipment. Multiple extension pipelines form one or more layers.

3. The method for calculating the pressure loss of compressed air foam for long-distance transportation applicable to UHV stations according to claim 2 is characterized in that: The compressed air foam spray pipe also includes a channel steel. The main pipe and the branch pipe are both arranged in the channel steel installed close to the firewall. The wrapping angle of the channel steel to the pipe is 150 to 180 degrees. The wall thickness of the extension pipe is greater than that of the main pipe and the branch pipe. The extension pipe is fixedly connected to the firewall through a bracket.

4. The method for calculating the pressure loss of compressed air foam long-distance transportation applicable to UHV stations according to claim 2 is characterized in that: The compressed air foam spray pipe also includes a first connecting pipe and a second connecting pipe. The main pipe is connected to the branch pipe through the first connecting pipe, and the first connecting pipe is connected to the extension pipe through the second connecting pipe. The first connecting pipe and the second connecting pipe are both multi-way structures.

5. The method for calculating the pressure loss of compressed air foam long-distance transportation applicable to UHV stations according to claim 4 is characterized in that: The compressed air foam spray pipe also includes an interface flange and a sealing gasket. Two interface flanges are provided at the interfaces of the main pipe, branch pipe, extension pipe and connecting pipe. A sealing gasket is provided between the two interface flanges. The interface flange can adjust the angle, and the sealing gasket is made of high-temperature resistant material.

6. The method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations according to claim 1 is characterized in that: The compressed air foam spray pipe further comprises a diversion pipe and a foam generating device, and the foam generating device is connected to the main pipes on both sides via the diversion pipe.

7. The method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations according to claim 1 is characterized in that: The compressed air foam spray pipe further comprises an end blocking piece, and the open ends of the main pipe, the branch pipe and the extension pipe are all provided with blocking pieces.

8. The method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations according to claim 1 is characterized in that: The main pipeline, branch pipeline and extension pipeline are all arranged horizontally. The installation height of the main pipeline is more than 0.5m higher than the main surface of the oil filling equipment. The installation height of the branch pipeline is higher than the upper surface of the key protection part of the oil filling equipment. The installation height of the extension pipeline is more than 0.5m higher than the upper surface of the key protection part of the oil filling equipment.

9. The method for calculating the pressure loss of compressed air foam in long-distance transportation suitable for ultra-high voltage stations according to claim 1, characterized in that: The release holes are arranged in three rows of upper, middle and lower on the pipeline surface. The release holes in the same row are evenly distributed, and the aperture of the release holes in the middle row is larger than that of the release holes in the upper and lower rows.

10. The method for calculating the pressure loss of compressed air foam long-distance transportation applicable to UHV stations according to claim 1, characterized in that: The main pipeline, branch pipeline and extension pipeline are all made by 3D printing.

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