Compressed nitrogen foam and spray combined fire extinguishing system and fire extinguishing method

Abstract

The invention discloses a compressed nitrogen foam and spray combined fire extinguishing system and a fire extinguishing method. The fire extinguishing system comprises a fire pump, a control system, a foam proportioning mixer, a liquid control valve, a high-pressure nitrogen cylinder, a gas control valve, a one-way valve, a compressed nitrogen foam generator, a fire main pipe and a release pipe, an outlet of the fire pump is connected with the foam proportioning mixer through a pipeline and then connected with a liquid inlet of the compressed nitrogen foam generator through a pipeline; the high-pressure nitrogen cylinder is decompressed, sequentially passes through the gas control valve and the one-way valve through a pipeline, and then is connected with a gas inlet of the compressed nitrogen foam generator; an outlet of the compressed nitrogen foam generator is connected with a fire-fighting main pipe; the fire-fighting main pipe is connected with a release pipe; and the control system respectively controls the actions of the foam proportioning mixer, the liquid control valve and the gas control valve. The device has the functions of foam isolation covering, nitrogen inert suffocation and water mist long-time continuous cooling, and the technical problem of transformer explosion fire suppression is thoroughly solved.

Description

Technical Field

[0001] This invention belongs to the field of fire extinguishing technology for power transformers, and relates to a fire extinguishing system and method that combines compressed nitrogen foam and spray. Background Technology

[0002] Currently, fire protection systems in 220kV substations mainly consist of fixed water mist and synthetic foam spray systems. Water mist systems primarily rely on the cooling effect of water mist to extinguish fires, possessing a strong cooling capacity. However, they suffer from insufficient fire control and extinguishing capabilities when extinguishing large-scale hot oil fires. Synthetic foam spray systems use high-pressure gas to drive the release of the extinguishing medium, making them suitable for areas without or lacking water. However, their foaming time is short, their resistance to reignition is weak, and their sustained cooling capacity is poor. In numerous fire incidents, they have failed to extinguish the fires. Furthermore, the premixed foam extinguishing medium used in these systems has issues such as short shelf life and poor insulation.

[0003] Existing compressed air foam fire extinguishing systems for UHV converter stations have high fire extinguishing efficiency and strong resistance to reignition, but they have high redundancy, large flow rate, and high equipment cost. In addition, they use air compressors as air sources, which consume a lot of electricity and are not economical, and cannot meet the needs of large-scale application in 220kV substations.

[0004] It is evident that existing fixed fire extinguishing systems, such as water spray fire extinguishing systems, foam spray fire extinguishing systems, and UHV converter station compressed air foam fire extinguishing systems, have certain shortcomings in fire control and extinguishing performance, continuous cooling capacity, economy, or applicability. They cannot simultaneously possess economic efficiency, high-efficiency fire extinguishing, and continuous cooling performance, and cannot meet the actual fire prevention and control needs of large substations such as 220kV. There is an urgent need for economical, efficient, safe, and applicable fire extinguishing technologies. Summary of the Invention

[0005] In view of the shortcomings of the existing fire extinguishing technologies, the present invention provides a fire extinguishing system and method that combines compressed nitrogen foam and spray, which has the functions of foam isolation and coverage, nitrogen inert asphyxiation and long-term continuous cooling of water mist, in order to solve the technical problems of fighting transformer explosion fires.

[0006] Therefore, the present invention adopts the following technical solution: a fire extinguishing system combining compressed nitrogen foam and spray, which includes a fire pump, a control system, a foam proportioner, a liquid control valve, a high-pressure nitrogen cylinder, a gas control valve, a check valve, a compressed nitrogen foam generator, a fire main pipe and a release pipe;

[0007] The outlet of the fire pump is connected to a foam proportioner via a pipe, and then connected to the inlet of a compressed nitrogen foam generator via another pipe.

[0008] The high-pressure nitrogen cylinder, after being depressurized, passes through a pipeline in sequence through a gas control valve and a one-way valve, and is then connected to the inlet of the compressed nitrogen foam generator.

[0009] The outlet of the compressed nitrogen foam generator is connected to the fire main pipe, and the fire main pipe is connected to the release pipe, through which the fire extinguishing medium (compressed nitrogen foam, foam mixture, water, etc.) is applied.

[0010] The control system controls the foam proportioner, liquid control valve, and gas control valve respectively.

[0011] Furthermore, the fire pump is a centrifugal pump with a rated operating pressure of 0.4 MPa to 1.2 MPa, and a pressure gauge is installed at its outlet, which is controlled by a control system. The foam proportioner can be a metering injection type foam proportioner, a balanced type foam proportioner, a mechanical pump-in type foam proportioner, or a pressure foam proportioner.

[0012] Furthermore, there are multiple high-pressure nitrogen cylinders, and multiple nitrogen outlet pipes are converged into a nitrogen transmission pipe through a high-pressure gas collecting pipe. A pressure gauge is installed at the outlet of the nitrogen transmission pipe, and the pressure gauge is controlled by a control system.

[0013] Furthermore, the working pressure of the high-pressure nitrogen cylinder delivered to the gas control valve and check valve after pressure reduction is 0.4MPa to 1.6MPa.

[0014] Furthermore, the release tube includes an external conduit and an internal sliding plate that is rotatable within the external conduit;

[0015] The surface of the external pipeline has spray holes and mist holes, which serve as release channels for compressed nitrogen foam. Spray nozzles are installed in the mist holes. The spray holes and mist holes are evenly distributed in multiple rows along the circumference of the external pipeline within a certain angle range, and are also evenly distributed in multiple columns along the length of the external pipeline.

[0016] The internal sliding plate is a thin plate with a certain angled arc in its cross-section. The length of the internal sliding plate is consistent with that of the external pipeline. The arc angle of the thin plate's cross-section is selected according to the required number of spray holes and mist holes.

[0017] Furthermore, the main body of the internal sliding piece is a thin metal sheet, with rubber sealing strips on both sides, and the two sides of the thin metal sheet are fixedly connected to the rubber sealing strips.

[0018] Furthermore, the outer diameter of the arc of the metal sheet cross section is slightly smaller than the inner diameter of the external pipeline, and there is a very small gap inside. It is installed coaxially with the release pipe. The rubber sealing strip fills the gap formed by the outer diameter of the internal sliding piece being slightly smaller than the inner diameter of the external pipeline from both ends in the circumferential direction until a sealing effect is achieved.

[0019] Furthermore, bearings are installed at both ends of the release tube, and a motor is installed at the end of the external pipeline. The output shaft of the motor is connected to the internal sliding plate. The motor is a stepper motor, which rotates the internal sliding plate quantitatively through pulse signals. The rotation angle corresponding to one pulse signal of the stepper motor causes the internal sliding plate to pass over a row of spray holes or a row of spray nozzles.

[0020] When the stepper motor is controlled by the pulse signal of the control system, it drives the internal slide plate to rotate to the position that only blocks the spray hole. At this time, the release pipe is in the state of conveying compressed nitrogen foam. When the pressure of the high-pressure nitrogen cylinder is detected to decrease, the stepper motor is controlled by the pulse signal of the control system, and it drives the internal slide plate to rotate to the position that only blocks the spray hole. At this time, the release pipe is in the state of conveying foam mixture or water.

[0021] This invention also provides a fire extinguishing method using compressed nitrogen foam and spray in combination. It adopts the above-mentioned compressed nitrogen foam and spray fire extinguishing system. In daily operation, spray is used for maintenance and inspection and transformer cooling. In case of fire, it first automatically switches to the state of generating, transporting and spraying compressed nitrogen foam. The compressed nitrogen foam is used for short-term rapid and efficient fire control and extinguishing. Then, according to the nitrogen consumption, it automatically switches to the state of transporting and spraying foam mixture and water, using spray and spray for long-term continuous cooling.

[0022] Furthermore, the above-mentioned fire extinguishing method combining compressed nitrogen foam and spray specifically includes:

[0023] 1) Routine Operation and Maintenance: The control system controls the stepper motor to keep the release pipe in the state of conveying foam mixture or water, starts the fire pump, and sprays mist through the atomizing nozzle to realize the routine operation and maintenance of the fire extinguishing system; at the same time, in hot weather or when there is too much dust in the transformer, the spray is used for cooling and cleaning.

[0024] 2) Firefighting: For transformer fires, a high-pressure nitrogen cylinder is used as the foaming gas power source to generate compressed nitrogen foam. An automatic stepper motor switches the release pipe to the compressed nitrogen foam delivery state. Firefighting is then carried out through the compressed nitrogen foam release device, ensuring the entire transformer fire protection area is completely covered by foam. Through the dual effects of isolation, coverage, and inertial asphyxiation, open flames are quickly controlled and extinguished. The gas-liquid ratio of the compressed nitrogen foam is 4:1 to 40:1, and the foam mixture supply intensity is 5 L / (min·m). 2 )~30L / (min·m 2 The continuous soaking time is 3 to 30 minutes;

[0025] 3) Continuous cooling: For residual concealed flames and potentially high-temperature areas around the transformer, continue operating the fire pumps and foam proportioner. Control the stepper motor to switch the release pipe to deliver foam mixture or water, spraying mist or water vapor through atomizing nozzles to continuously cool the transformer, ensuring complete fire extinguishing and thorough cooling, effectively preventing reignition. The supply rate of foam mixture or water is 5 L / (min·m). 2 )~50L / (min·m 2 The continuous spraying time is 5 min to 200 min.

[0026] The beneficial effects of this invention are:

[0027] 1. This invention adopts a fire extinguishing method of "first using compressed nitrogen foam for a short time to quickly and efficiently control and extinguish the fire, and then using spray and spray for a long time to continuously cool down the fire". It has the characteristics of fast fire control and extinguishing speed, strong anti-reignition performance, excellent cooling and cooling capacity, safety and reliability, and economic efficiency. It solves the problem that existing technologies cannot achieve both high-efficiency fire extinguishing, continuous cooling and safety and economy at the same time.

[0028] 2. This invention uses a high-pressure nitrogen cylinder instead of an expensive and power-consuming air compressor as the power source for foaming gas. This not only achieves the replacement of compressed air foam with compressed nitrogen foam, improving the foam's fire extinguishing and anti-reignition performance, giving the foam excellent isolation coverage and inert asphyxiation dual functions, but also reduces costs and significantly reduces power consumption, fully meeting the actual fire prevention and control needs of 220kV substations.

[0029] 3. This invention uses a stepper motor to control the foam-spray conversion, which not only realizes the automatic, timely and highly reliable switching between the two states of "foam-spray", but also allows for the release of the same extinguishing medium to correspond to the fire situation at different locations and structures of the transformer. According to the actual fire situation, different numbers of pulse signals can be given in a timely manner to adjust the position of the internal sliding plate, close some holes, and increase the release pressure of the remaining holes. This allows for flexible adjustment of the position and flow rate of the extinguishing medium that can be applied, which is beneficial for targeted extinguishing of hidden fires.

[0030] 4. The fire extinguishing system of this invention is technologically advanced, economical and efficient, automatic and reliable, and easy to use. It combines the functions of foam isolation and coverage, nitrogen inert asphyxiation, and water mist for long-term continuous cooling, completely solving the technical problems of transformer explosion fire fighting and the fire prevention and control problems of major urban substations. It can be used in both newly built large substations and existing large substations. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram illustrating the principle of the compressed nitrogen foam and spray combined fire extinguishing system of the present invention;

[0033] Figure 2 This is a schematic diagram of the piping layout of the compressed nitrogen foam and spray combined fire extinguishing system of the present invention;

[0034] Figure 3 This is a schematic diagram of the release pipe structure of the compressed nitrogen foam and spray combined fire extinguishing system of the present invention;

[0035] Figure 4 This is a schematic diagram of the internal sliding plate, bearing, and stepper motor of the release tube of the present invention;

[0036] Figure 5 This is a schematic diagram of the internal structure of the release tube of the present invention when the sliding plate inside controls the release of compressed nitrogen foam;

[0037] Figure 6 This is a schematic diagram of the internal structure of the release tube of the present invention when the sliding plate controls the release of the spray.

[0038] Figure label:

[0039] 1 is a fire pump, 2 is a control system, 3 is a foam proportioner, 4 is a liquid control valve, 5 is a high-pressure nitrogen cylinder, 6 is a high-pressure gas collection pipe, 7 is a gas control valve, 8 is a check valve, 9 is a compressed nitrogen foam generator, 10 is a fire main pipe, 11 is a release pipe, 11-1 is an external pipeline, 11-1a is a sprinkler hole, 11-1b is a spray hole, 11-2 is an internal sliding vane, 11-2a is a metal sheet, 11-2b is a rubber sealing strip, 12 is a bearing, 13 is a stepper motor, and 14 is a spray nozzle. Detailed Implementation

[0040] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a fire extinguishing system that combines compressed nitrogen foam and spray, such as... Figure 1-6 As shown, it consists of a fire pump 1, a control system 2, a foam proportioner 3, a liquid control valve 4, a high-pressure nitrogen cylinder 5, a high-pressure gas collection pipe 6, a gas control valve 7, a one-way valve 8, a compressed nitrogen foam generator 9, a fire main pipe 10, and a release pipe 11.

[0043] The outlet of the fire pump 1 is connected to the foam proportioner 3 via a pipeline, and then connected to the inlet of the compressed nitrogen foam generator 9 via another pipeline. The fire pump 1 is a centrifugal pump with a rated operating pressure of 0.4 MPa to 1.2 MPa. A pressure gauge is installed at its outlet, and this pressure gauge is controlled by the control system 2. The foam proportioner 3 is a metering injection type foam proportioner, a balanced type foam proportioner, a mechanical pump-in type foam proportioner, or a pressure foam proportioner.

[0044] The high-pressure nitrogen cylinder 5, after being depressurized, passes through a pipeline sequentially via a gas control valve 7 and a one-way valve 8, and is then connected to the inlet of the compressed nitrogen foam generator 9. The high-pressure nitrogen cylinder 5 is a 40L or 60L high-pressure nitrogen cylinder with a storage pressure of 10MPa to 18MPa. After depressurization, the working pressure delivered to the gas control valve 7 and the one-way valve 8 is 0.4MPa to 1.6MPa. There are multiple high-pressure nitrogen cylinders, and multiple nitrogen outlet pipes are converged into a nitrogen delivery pipe through a high-pressure gas collecting pipe 6. A pressure gauge is installed at the outlet of this nitrogen delivery pipe, and the pressure gauge is controlled by the control system 2.

[0045] The outlet of the compressed nitrogen foam generator 9 is connected to the fire main pipe 10, which is connected to the release pipe 11 for applying the extinguishing agent. The distance between the release pipe and the transformer is not less than 1m. The release pipe is a modified TFR-100 type sprinkler pipe with a foam spray coverage distance of 2m to 12m and is made of corrosion-resistant metal material.

[0046] The control system 2 controls the operation of the foam proportioner 3, the liquid control valve 4, and the gas control valve 7 respectively.

[0047] The release tube 11 includes an external tube 11-1 and an internal sliding plate 11-2 that is rotatable within the external tube 11-1.

[0048] The surface of the external pipeline 11-1 has spray holes 11-1a and spray nozzles 11-1b, which serve as release channels for compressed nitrogen foam. Spray nozzles are installed at the spray holes, with an effective spray distance of 3 to 8 meters. They are made of corrosion-resistant metal. The spray holes 11-1a and spray nozzles 11-1b are evenly distributed in multiple rows along the circumference of the external pipeline 11-1 within a certain angle range, and are also evenly distributed in multiple columns along the length of the external pipeline 11-1.

[0049] The internal sliding plate 11-2 is a thin plate with a certain angled arc in its cross section. The length of the internal sliding plate 11-2 is consistent with that of the external pipeline 11-1. The arc angle of the thin plate cross section is selected according to the number of spray hole positions 11-1a and spray hole positions 11-1b to be set.

[0050] The main body of the internal sliding piece 11-2 is a thin metal sheet 11-2a, and the two sides are rubber sealing strips 11-2b. The two sides of the thin metal sheet 11-2a are fixedly connected to the rubber sealing strips 11-2b.

[0051] The outer diameter of the arc of the cross-section of the metal sheet 11-2a is slightly smaller than the inner diameter of the external pipe, and there is a very small gap inside. It is installed coaxially with the release pipe. The rubber sealing strip 11-2b fills part of the gap formed by the outer diameter of the inner sliding plate 11-2 being slightly smaller than the inner diameter of the external pipe 11-1 from both ends in the circumferential direction.

[0052] The release tube 11 is equipped with bearings 12 at both ends, and a motor 13 is installed at the end of the external pipe 11-1. The output shaft of the motor is connected to the internal slide plate 11-2. The motor 13 is a stepper motor, which rotates the internal slide plate 11-2 quantitatively through pulse signals. The rotation angle corresponding to one pulse signal of the stepper motor causes the internal slide plate to pass over a row of spray holes 11-1a or a row of spray holes 11-1b.

[0053] When the stepper motor is controlled by the pulse signal of the control system, it drives the internal slider 11-2 to rotate to the position that only blocks the spray hole 11-1b. At this time, the release pipe is in the state of conveying compressed nitrogen foam. When the pressure of the high-pressure nitrogen cylinder is detected to decrease, the stepper motor is controlled by the pulse signal of the control system, and drives the internal slider 11-2 to rotate to the position that only blocks the spray hole 11-1a. At this time, the release pipe is in the state of conveying foam mixture or water.

[0054] Example 2

[0055] This embodiment provides a fire extinguishing method that combines compressed nitrogen foam and spray. It adopts the compressed nitrogen foam and spray fire extinguishing system described in Embodiment 1. In daily operation, spray is used for maintenance and inspection as well as transformer cooling. In case of fire, it first automatically switches to the state of generating, delivering and spraying compressed nitrogen foam. The compressed nitrogen foam is used for short-term rapid and efficient fire control and extinguishing. Then, according to the nitrogen consumption, it automatically switches to the state of delivering and spraying foam mixture and water, using spray and spray for long-term continuous cooling.

[0056] The specific details of the above-mentioned fire extinguishing method combining compressed nitrogen foam and spray are as follows:

[0057] 1) Routine Operation and Maintenance: The control system controls the stepper motor to keep the release pipe in the state of conveying foam mixture or water, starts the fire pump, and sprays mist through the atomizing nozzle to realize the routine operation and maintenance of the fire extinguishing system; at the same time, in hot weather or when there is too much dust in the transformer, the spray is used for cooling and cleaning.

[0058] 2) Firefighting: For transformer fires, a high-pressure nitrogen cylinder is used as the foaming gas power source to generate compressed nitrogen foam. An automatic stepper motor switches the release pipe to the compressed nitrogen foam delivery state. Firefighting is then carried out through the compressed nitrogen foam release device, ensuring the entire transformer fire protection area is completely covered by foam. Through the dual effects of isolation, coverage, and inertial asphyxiation, open flames are quickly controlled and extinguished. The gas-liquid ratio of the compressed nitrogen foam is 4:1 to 40:1, and the foam mixture supply intensity is 5 L / (min·m). 2 )~30L / (min·m 2 The continuous soaking time is 3 to 30 minutes;

[0059] 3) Continuous cooling: For residual concealed flames and potentially high-temperature areas around the transformer, continue operating the fire pumps and foam proportioner. Control the stepper motor to switch the release pipe to deliver foam mixture or water, spraying mist or water vapor through atomizing nozzles to continuously cool the transformer, ensuring complete fire extinguishing and thorough cooling, effectively preventing reignition. The supply rate of foam mixture or water is 5 L / (min·m). 2 )~50L / (min·m 2 The continuous spraying time is 5 min to 200 min.

[0060] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and edibility purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A fire extinguishing system combining compressed nitrogen foam and spray, characterized in that, It includes a fire pump (1), a control system (2), a foam proportioner (3), a liquid control valve (4), a high-pressure nitrogen cylinder (5), a gas control valve (7), a check valve (8), a compressed nitrogen foam generator (9), a fire main pipe (10), and a release pipe (11); The outlet of the fire pump (1) is connected to the foam proportioner (3) through a pipe, and then connected to the inlet of the compressed nitrogen foam generator (9) through a pipe. The high-pressure nitrogen cylinder (5) is depressurized and then passes through a gas control valve (7) and a check valve (8) in sequence through a pipeline before being connected to the inlet of the compressed nitrogen foam generator (9). The outlet of the compressed nitrogen foam generator (9) is connected to the fire main pipe (10), and the fire main pipe (10) is connected to the release pipe (11); The control system (2) controls the foam proportioner (3), the liquid control valve (4) and the gas control valve (7) respectively.

2. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 1, characterized in that, The fire pump (1) is a centrifugal pump with a rated working pressure of 0.4MPa to 1.2MPa. A pressure gauge is installed at its outlet, and the pressure gauge is controlled by the control system (2).

3. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 1, characterized in that, There are multiple high-pressure nitrogen cylinders (5), and multiple nitrogen outlet pipes are converged into a nitrogen transmission pipe through a high-pressure gas collecting pipe (6). A pressure gauge is provided at the outlet of the nitrogen transmission pipe, and the pressure gauge is controlled by a control system (2).

4. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 1, characterized in that, The working pressure of the high-pressure nitrogen cylinder (5) delivered to the gas control valve (7) and the one-way valve (8) after pressure reduction is 0.4MPa to 1.6MPa.

5. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 1, characterized in that, The release tube (11) includes an external pipe (11-1) and an internal sliding plate (11-2) that is rotatable inside the external pipe (11-1); The surface of the external pipeline (11-1) has spray holes (11-1a) and spray nozzles (11-1b) to serve as release channels for compressed nitrogen foam. Spray nozzles (14) are installed in the spray holes. The spray holes (11-1a) and spray nozzles (11-1b) are evenly distributed in multiple rows along the circumference of the external pipeline (11-1) within a certain angle range, and are also evenly distributed in multiple columns along the length of the external pipeline (11-1). The inner sliding plate (11-2) is a thin plate with a certain angled arc in cross section. The length of the inner sliding plate (11-2) is consistent with that of the outer pipeline (11-1). The arc angle of the thin plate cross section is selected according to the number of spray hole positions (11-1a) and spray hole positions (11-1b) to be set.

6. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 5, characterized in that, The main body of the internal sliding piece (11-2) is a thin metal sheet (11-2a), and the two sides are rubber sealing strips (11-2b). The two sides of the thin metal sheet (11-2a) are fixedly connected to the rubber sealing strips (11-2b).

7. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 6, characterized in that, The outer diameter of the arc of the cross section of the metal sheet (11-2a) is slightly smaller than the inner diameter of the external pipeline, and there is a gap inside. It is installed coaxially with the release pipe. The rubber sealing strip (11-2b) fills the gap formed by the outer diameter of the inner sliding plate (11-2) being slightly smaller than the inner diameter of the external pipeline (11-1) from both ends in the circumferential direction.

8. The compressed nitrogen foam and spray combined fire extinguishing system according to claim 1, characterized in that, The release tube (11) is equipped with bearings (12) at both ends, and a motor (13) is installed at the end of the external pipeline (11-1). The output shaft of the motor is connected to the internal slide (11-2). The motor (13) is a stepper motor, which rotates the internal slide (11-2) quantitatively through pulse signals. The rotation angle corresponding to one pulse signal of the stepper motor causes the internal slide to pass over a row of spray holes (11-1a) or a row of spray holes (11-1b). When the stepper motor is controlled by the pulse signal of the control system, it drives the internal slider (11-2) to rotate to the position that only blocks the spray hole (11-1b). At this time, the release pipe is in the state of conveying compressed nitrogen foam. When the pressure of the high-pressure nitrogen cylinder is detected to decrease, the stepper motor is controlled by the pulse signal of the control system, and drives the internal slider (11-2) to rotate to the position that only blocks the spray hole (11-1a). At this time, the release pipe is in the state of conveying foam mixture or water.

9. A method for extinguishing fires using compressed nitrogen foam and spray in combination, comprising the compressed nitrogen foam and spray fire extinguishing system as described in any one of claims 1-8, characterized in that, In routine maintenance and inspection, as well as transformer cooling, the system uses spray for spraying. In case of fire, it automatically switches to generating, delivering, and spraying compressed nitrogen foam. The compressed nitrogen foam is used for short-term, rapid, and efficient fire control and extinguishing. Then, based on nitrogen consumption, it automatically switches to delivering and spraying foam mixture and water for long-term, continuous cooling.

10. The fire extinguishing method using compressed nitrogen foam and spray in combination according to claim 9, characterized in that, Specifically, it includes: 1) Routine Operation and Maintenance: The control system controls the stepper motor to keep the release pipe in the state of conveying foam mixture or water, starts the fire pump, and sprays mist through the atomizing nozzle to realize the routine operation and maintenance of the fire extinguishing system; at the same time, in hot weather or when there is too much dust in the transformer, the spray is used for cooling and cleaning. 2) Firefighting: For transformer fires, a high-pressure nitrogen cylinder is used as the foaming gas power source to generate compressed nitrogen foam. An automatic stepper motor switches the release pipe to the compressed nitrogen foam delivery state. Firefighting is then carried out through the compressed nitrogen foam release device, ensuring the entire transformer fire protection area is completely covered by foam. Through the dual effects of isolation, coverage, and inertial asphyxiation, open flames are quickly controlled and extinguished. The gas-liquid ratio of the compressed nitrogen foam is 4:1 to 40:1, and the foam mixture supply intensity is 5 L / (min·m). 2 )~30L / (min·m 2 The continuous soaking time is 3 to 30 minutes; 3) Continuous cooling: For residual concealed flames and potentially high-temperature areas around the transformer, continue operating the fire pumps and foam proportioner. Control the stepper motor to switch the release pipe to deliver foam mixture or water, spraying mist or water vapor through atomizing nozzles to continuously cool the transformer, ensuring complete fire extinguishing and thorough cooling, effectively preventing reignition. The supply rate of foam mixture or water is 5 L / (min·m). 2 )~50L / (min·m 2 The continuous spraying time is 5 min to 200 min.

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