CN107737430A - For the design method of the water smoke live-wire fire fighting device of power transformer fire - Google Patents
For the design method of the water smoke live-wire fire fighting device of power transformer fire Download PDFInfo
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62C—FIRE-FIGHTING
- A62C37/00—Control of fire-fighting equipment
- A62C37/50—Testing or indicating devices for determining the state of readiness of the equipment
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62C—FIRE-FIGHTING
- A62C3/00—Fire prevention, containment or extinguishing specially adapted for particular objects or places
- A62C3/16—Fire prevention, containment or extinguishing specially adapted for particular objects or places in electrical installations, e.g. cableways
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- A—HUMAN NECESSITIES
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Abstract
The invention discloses a kind of design method of the water smoke live-wire fire fighting device for power transformer fire, including to water smoke parameter Preliminary design；Simulate fire-extinguishing test and the water smoke parameter to Preliminary design optimizes；The water smoke live-wire fire fighting device of power transformer is designed；Distance is discharged in design, ensures the safety of live-wire fire fighting.The design method of this water smoke live-wire fire fighting device for power transformer fire provided by the invention, for the concrete application of power transformer fire, the powered safety conditions of water smoke and high-effect fire-extinguishing requirement are considered comprehensively, it is proposed is directed to the powered high-effect fire-extinguishing equipment Design of water smoke and application process of power transformer fire, design for the powered high-effect fire-extinguishing equipment of power transformer fire provides feasible scheme with application, and the inventive method considers the working environment parameter of power transformer comprehensively, design result is more accurate, safe and reliable.
Description
Technical Field
The invention particularly relates to a design method of a water mist electrified fire extinguishing device for a power transformer fire.
Background
With the development of national economic technology and the improvement of living standard of people, electric energy becomes essential secondary energy in daily production and life of people, and brings endless convenience to the production and life of people. However, in recent years, with the accelerated construction of the global energy internet and the extra-high voltage power grid, power fires frequently occur, large-scale and long-time power failure accidents are often caused, and the safe operation of the power grid is seriously influenced. The electric fire prevention and control needs to meet the requirements of live fire extinguishing and efficient fire extinguishing at the same time, so the prevention and control difficulty is high, and the electric fire prevention and control method is an international problem in the field of fire prevention and control.
The power transformer contains a large amount of hydrocarbon mineral oil, has strong flammability, and has fire and explosion risks when a fault occurs. The transformer is a power hub of the power energy Internet, and in case of fire, a large-area and long-time power failure accident is caused, so that the protection risk cannot be ignored. The existing power transformer fire prevention and control all adopt fixed fire extinguishing systems, and the water spraying and foam spraying fixed fire extinguishing systems (such as patent CN 203108057U) which are used in large quantity at present adopt spraying water and foam with strong conductivity, so that the electrified fire extinguishing can not be realized, and short circuit trip is easily caused during misoperation, so that great operation risk exists.
Disclosure of Invention
The invention aims to provide a design method of a water mist live fire extinguishing device for a power transformer fire, which is designed for the power transformer fire, can carry out live fire extinguishing and ensures the system safety.
The invention provides a design method of a water mist electrified fire extinguishing device for a power transformer fire, which comprises the following steps:
s1, preliminarily designing parameters of water mist according to the safety requirement of charged fire extinguishing;
s2, according to the water mist parameters designed in the step S1, carrying out a fire simulation fire extinguishing test aiming at the specific type of the power transformer fire, and thus optimizing the preliminarily designed water mist parameters;
s3, designing a water mist electrified fire extinguishing device of the power transformer according to the water mist parameters optimized in the step S2;
s4, designing the discharge distance of the water mist to the electrified end in the power transformer, thereby ensuring the safety of electrified fire extinguishing.
The safety requirement in the step S1 is specifically to prevent flashover, tripping and power failure between high-voltage bushings of the power transformer or from the bushings to the ground.
The safety requirement is that the breakdown field intensity of the water mist is not less than 0.9 time of the breakdown flashover phenomenon of the air under the same condition.
And S1, preliminarily designing parameters of the water mist according to the safety requirement of charged fire extinguishment, specifically simulating a haze pollution level and a high-voltage bushing pollution level in an application environment of the power transformer according to the highest withstand voltage, water agent conductivity, atmospheric pressure and an electrode model, and preliminarily designing the parameters of the water mist.
The maximum withstand voltage adopts the rated voltage of a power transformer.
The electrode model adopts a spray head-high voltage sleeve model.
The atmospheric pressure is selected by adopting the following principle: the atmospheric pressure in the area below the altitude of 2000m is selected to be 101kPa, and the atmospheric pressure in the area above the altitude of 2000m is selected to be 80kPa; the temperature of the atmosphere is fixed at 20 ℃, and the humidity of the atmosphere is fixed at 50%.
The haze pollution grade adopts a three-level haze pollution grade specified by the national standard, and the high-voltage bushing pollution grade adopts a five-level pollution grade specified by the national standard.
The parameters of the water mist are preliminarily designed in the step S1, and specifically, the parameters of the water mist and the fog drops comprise volume characteristic diameter, mean particle size of Sotella, concentration of the fog drops and three-dimensional speed of the fog drops.
The specific type of the power transformer fire in step S2 is specifically determined by adopting the following rules: determining the fire type of the power transformer as B-type oil fire; the simulated combustion of fire adopts 25# or 40# paraffin-based transformer oil or naphthenic transformer oil.
S3, designing the water mist electrified fire extinguishing device of the power transformer, specifically adopting the following steps to design:
A. designing a water mist spray head according to the following formula:
in the formula q i The flow rate of a single spray head, K is the flow coefficient of the spray head, and P is the designed working pressure of the spray head;
B. the design of the pipeline transmission system is carried out according to the following formula:
wherein Q is the design flow of the fire extinguishing device, n is the total number of the spray heads, and Q is the total number of the spray heads i The flow of the ith nozzle is shown, i is a natural number;
C. the pressure system design is carried out according to the following formula:
H＝∑h+P 0 +h z
where H is the supply pressure of the pump head or system inlet, Σ H is the accumulated value of the loss of water head along the pipeline and part, P 0 The operating pressure of the worst spray point (the lowest spray pressure of the spray head due to the longest distance from the pressure source, the longest distance to be delivered, or the highest vertical distance), h z The lift difference between the spraying point of the least favorable water mist and the central line of the lowest water mist or system horizontal water supply inlet pipe is obtained;
wherein the pipeline on-way and local head loss comprises pipeline head loss, equipment valve head loss and pipe fitting local head loss;
the pipeline head loss is calculated by adopting the following formula:
in the formula h g F is friction resistance loss, f is a friction coefficient, L is the length of the pipeline, rho is liquid density, Q is flow, and d is the diameter of the pipeline;
the friction coefficient f is obtained by inquiring a Modi diagram according to the Reynolds number; the Reynolds number is calculated by the following formula:
in the formula, re is Reynolds number, mu is absolute dynamic viscosity;
D. and designing a control system of the automatic fire extinguishing device so as to realize automatic fire extinguishing.
Step S4, designing the discharge distance of the charged end, specifically, designing by using the following principle: dividing the safe distance of the existing power equipment by the electrified safe correction coefficient to obtain the safe distance under the water mist environment, and designing the water mist discharge distance according to the safe distance under the water mist environment; the electrified safety correction coefficient is defined as the ratio of the breakdown voltage of the water mist to the breakdown voltage of the air under the same condition.
The design method of the water mist electrified fire extinguishing device for the power transformer fire provided by the invention comprehensively considers the water mist electrified safety condition and the high-efficiency fire extinguishing requirement aiming at the specific application of the power transformer fire, provides the design and application method of the water mist electrified high-efficiency fire extinguishing device for the power transformer fire, and provides a feasible scheme for the design and application of the power transformer fire electrified high-efficiency fire extinguishing device.
Drawings
FIG. 1 is a flow chart of the method of the present invention.
Fig. 2 is a schematic diagram of water mist parameter initialization design parameters in an embodiment of the invention.
Detailed Description
FIG. 1 shows a flow chart of the method of the present invention: the invention provides a design method of a water mist electrified fire extinguishing device for a power transformer fire, which comprises the following steps:
s1, preliminarily designing parameters of water mist according to the safety requirement of charged fire extinguishing;
the safety requirement is specifically to prevent flashover, tripping and power failure between high-voltage bushings of the power transformer or between the bushings to the ground; due to the existence of water mist, the specific embodiment of preventing flashover tripping and power failure is as follows: the breakdown field intensity of the water mist in the breakdown flashover phenomenon is not less than 0.9 time of the breakdown field intensity of the air in the breakdown flashover phenomenon under the same condition;
preliminarily designing the parameters of the water mist, specifically simulating the pollution level of the haze and the pollution level of a high-voltage bushing in the application environment of the power transformer according to the highest withstand voltage, the conductivity of the water agent, the atmospheric pressure and an electrode model, and preliminarily designing the parameters of the water mist;
in specific implementation, the rated voltage of the power transformer is adopted as the highest withstand voltage;
the electrode model adopts a spray head-high voltage sleeve model;
the selection principle of atmospheric pressure is as follows: atmospheric pressure affects the breakdown voltage of water mist. The lower the atmospheric pressure, the lower the breakdown voltage. However, for high altitude areas such as non-Tibet plateau, cloud plateau and the like, the difference of the atmospheric pressure is small; therefore, the atmospheric pressure in the area with an altitude of 2000m or less is selected to be 101kPa, and the atmospheric pressure in the area with an altitude of 2000m or more is selected to be 80kPa; the temperature of the atmosphere is fixed to be 20 ℃, and the humidity of the atmosphere is fixed to be 50%;
the haze pollution grade adopts a three-level haze pollution grade specified by the national standard, and the high-voltage bushing pollution grade adopts a five-level pollution grade specified by the national standard;
the conductivity of the water agent is the conductivity of the selected fire extinguishing water agent and is a fixed value;
in addition, the parameters of the water mist are preliminarily designed, and specifically, the parameters of the water mist droplets comprise volume characteristic diameter Dv99, sotella mean particle diameter SMD, droplet concentration and droplet three-dimensional speed;
in the research process, the haze pollution level and the high-voltage bushing pollution level of the application environment obviously influence the insulation performance of the water mist, wherein the haze pollution level influences the breakdown voltage of the water mist, and the high-voltage bushing pollution level obviously influences the surface flashover voltage of the water mist on the high-voltage bushing of the transformer. Moreover, for similar altitude areas all over the country, the haze pollution level and the high-voltage bushing pollution level are obviously different, so that the targeted research and design are needed. Aiming at different haze pollution levels and high-voltage bushing pollution levels, the parameters of the water mist and fog drops suitable for electrified fire extinguishment have obvious differences. Therefore, when the preliminary design is carried out, the electrified safety of the water mist is initially designed according to the haze pollution level and the high-voltage bushing pollution level of the application environment, and a fog droplet parameter interval graph which accords with the electrified safety standard is drawn: the graph is divided into areas according to the haze pollution level and the high-voltage bushing pollution level, and then the area is divided into areas for researching a charged safe fog drop parameter interval, and is specifically shown in figure 2; in the figure, dv99 is the volume characteristic diameter, dv90 is the particle size corresponding to 90% in the volume distribution, SMD is the sotalol average particle size, and the K value is the ratio of the breakdown voltage of the water mist to the breakdown voltage of the air under the same conditions;
s2, according to the water mist parameters designed in the step S1, carrying out a fire simulation fire extinguishing test aiming at the specific type of the power transformer fire, and thus optimizing the preliminarily designed water mist parameters;
the specific type of power transformer fire is determined as follows: determining the fire type of the power transformer as B-type oil fire; the simulated combustion of the fire adopts 25# or 40# paraffin-based transformer oil or naphthenic transformer oil;
when a fire simulation fire extinguishing test is carried out in a large-scale artificial environment laboratory, parameters such as atmospheric pressure, temperature and humidity, haze pollution level and high-pressure sleeve pollution level in the laboratory are all controllable, an atmospheric pressure adjusting system is adopted for adjusting the atmospheric pressure, a temperature and humidity control system is adopted for adjusting the temperature and the humidity of the laboratory, a haze generating device is adopted for simulating haze pollution, and a national standard method is adopted for coating simulation of high-pressure sleeve pollution;
s3, designing a water mist electrified fire extinguishing device of the power transformer according to the water mist parameters optimized in the step S2; the design of the flow and the total flow of the water mist spray heads in the fire extinguishing equipment refers to the existing GB50898-2013 standard, the hydraulic design refers to the existing GB50898-2013 standard, GB 50151-2010 standard and NFPA 750 standard and a Darcy-Weis-bach (Darcy-Weiz) formula, and the design is specifically carried out by adopting the following steps:
A. designing a water mist spray head according to the following formula:
in the formula q i The flow rate of a single spray head, K is the flow coefficient of the spray head, and P is the designed working pressure of the spray head;
B. the pipeline transmission system is designed according to the following formula:
wherein Q is the design flow of the fire extinguishing device, n is the total number of the spray heads, and Q is the total number of the spray heads i The flow of the ith nozzle is shown, i is a natural number;
C. the pressure system design is carried out according to the following formula:
H＝∑h+P 0 +h z
where H is the supply pressure of the pump head or system inlet, Σ H is the accumulated value of the loss of water head along the pipeline and part, P 0 The operating pressure of the worst spray point (the lowest spray pressure of the spray head due to the longest distance from the pressure source, the longest distance to be delivered, or the highest vertical distance), h z The lift difference between the spraying point of the least favorable water mist and the central line of the lowest water mist or system horizontal water supply inlet pipe is obtained;
wherein the pipeline on-way and local head loss comprises pipeline head loss, equipment valve head loss and pipe fitting local head loss;
the pipeline head loss is calculated by adopting the following formula:
in the formula h g F is friction resistance loss, f is a friction coefficient, L is the length of the pipeline, rho is liquid density, Q is flow, and d is the diameter of the pipeline;
the friction coefficient f is obtained by inquiring a Modi diagram according to the Reynolds number; the Reynolds number is calculated by the following formula:
wherein Re is Reynolds number, mu is absolute dynamic viscosity;
D. a control system of the automatic fire extinguishing device is designed, so that automatic fire extinguishing is realized;
s4, designing the discharge distance of the water mist to a charged end in the power transformer, so that the safety of charged fire extinguishing is ensured; the design is specifically carried out by adopting the following principle: dividing the safe distance of the existing power equipment (for example, 1.5m when the electrified safe distance is 110kV, the electrified safe distance of 220kV is 3.0 m) by the electrified safe correction coefficient to obtain the safe distance under the water mist environment, and designing the water mist discharge distance according to the safe distance under the water mist environment; the electrified safety correction coefficient is defined as the ratio of the breakdown voltage of the water mist to the breakdown voltage of the air under the same condition.
The process of the invention is further illustrated below with reference to two examples:
the first embodiment is as follows: design of electrified high-efficiency fire extinguishing device for outdoor unattended transformer of certain 220kV in Tangshan
1) The outdoor unattended transformer water mist voltage class of a certain 220kV in Tangshan is 220kV, and because a fixed fire extinguishing device is adopted for fire extinguishing and unattended operation is adopted, the safety requirement of preventing flashover tripping and power failure between high-voltage bushings or between bushings to the ground is only required to be met.
2) The voltage class of the transformer is known to be 220kV, namely the highest endurance voltage is 220kV; the transformer is located in an area with an altitude of less than 150m, so that a standard atmospheric pressure of 101kPa is adopted; the conductivity of the adopted fire extinguishing water agent is 400 mu s/cm; the electrode model adopts a spray head-high voltage sleeve model.
3) Carrying out a water mist insulation performance test; the fine water mist generating pump set generates fine water mist with adjustable droplet parameters; measuring the fog drop parameters by adopting PDPA; generating high voltage by adopting a power supply module; the atmospheric pressure is adjusted by an atmospheric pressure adjusting device, and the environmental temperature is controlled to be 20 ℃ and the humidity is controlled to be 50% by a temperature and humidity control system. A haze generating device is adopted to simulate haze pollution, and a coating method is adopted to coat the insulating sleeve with dirt. Breakdown voltage test of the test the water mist breakdown voltage value was measured using a 50% withstand voltage method. Simulating the haze pollution level and the high-voltage bushing pollution level of an application environment, carrying out initialization design on the electrified safety of water mist, and drawing a fog drop parameter interval graph and an electrified safety correction coefficient K value graph which accord with the electrified safety standard;
4) As the Tangshan belongs to the China heavy industry base, the environmental pollution is serious, the haze pollution level reaches 2-3 levels, and the high-voltage bushing pollution level reaches 3-4 levels, so that the fog drop parameter interval meeting the electrified safety requirement standard of the ground is Dv99:<325mm；Dv90：<450mm；SMD：<, 538mm; fog drop concentration:<6g/m 2 s; three-dimensional speed of fog drops:&7m/s; k value: 0.91.
5) Aiming at the specific type of the fire, a fire simulation test is developed to obtain the optimal droplet diameter parameter of the water mist capable of realizing charged high-efficiency fire extinguishing. The transformer oil fire is a B-type fire, and the transformer fire is simulated by using the oil fire model. The design wind speed of the Tangshan area is 4 grades, which is in accordance with the annual larger wind power level of the Tangshan area. And obtaining the relation between the simulated fire extinguishing efficiency and the fog drop parameters. In the droplet diameter parameter section which is obtained in the previous step and can be applied to charged fire extinguishing, the droplet diameter parameter of the charged high-efficiency fire extinguishing of the water mist is optimized and selected, so that the water mist has the charged fire extinguishing performance and the high-efficiency fire extinguishing performance simultaneouslyThe parameters are: dv99:280-300mm; dv90:400mm; SMD:488mm; fog drop concentration: 6g/m 2 S; three-dimensional speed of fog drops: 5-6m/s; .
5) The diameter optimization parameters of the droplets of the electrified and efficient water mist fire extinguishing device obtained by the design are utilized to comprehensively design the electrified water mist fire extinguishing device, and the electrified water mist fire extinguishing device comprises a water mist spray head, a device pressure system, a pipeline transmission system and an automatic electrified fire extinguishing system. The specific design process is as follows:
(1) and designing a water mist spray head. By adjusting the K coefficient, pressure and flow value of the spray head, the spray droplet parameters of the spray head are designed to basically accord with the design parameters. Single nozzle flow q i Calculated according to the following formula:
calculating to obtain the flow q of a single spray head i ＝15L/min。
(2) Designing a pipeline transmission system. The 50 nozzle design is used, therefore, the total flow design for the pipeline is calculated according to the following formula:
calculated Q =750L/min.
The design requirement according to the pipeline diameter is as follows: the flow rate of the liquid in the pipe is preferably less than 5m/s, the pipe diameter being chosen to be 80mm. The pipeline material is stainless steel pipe.
(3) And designing a pressure system of the device. The supply pressure of the fire-extinguishing installation is calculated using the following formula:
H＝∑h+P 0 +h z
where, Σ h = h g (pipeline head loss) + h f (local head loss of equipped valves, pipes, etc.), wherein: h is the supply pressure (MPa) of the water pump lift or the system inlet, and the local head loss H of equipment valves, pipe fittings and the like f Explained by using the current national standard GB 50084 and GB 50219Calculating data to obtain sigma h =2MPa;
P 0 the working pressure of the worst water mist spraying point is set as the highest pressure of the equipment, namely 7MPa; h is a total of z The lift difference between the spraying point of the least favorable water mist and the central line of the lowest water mist or the horizontal water supply inlet pipe of the system is 5MPa.
Finally, the water pump lift or the supply pressure H =7+5+2=14MPa at the system inlet is obtained through calculation. This value is the head pressure required for the equipment design. The pressure system selects a plunger pump as the pressure pump group.
(4) The automatic induction fire extinguishing of the fire extinguishing device is controlled, and the electrified high-efficiency fire extinguishing is realized.
6) According to the electrified safety correction coefficient K value graph, parameters of water mist discharge distance and equipment installation distance are designed, and the electrified safety requirement is guaranteed. The charged safety distance under 220kV air is 3.0m. Therefore, according to the K value of 0.91 obtained above, the water mist electrification safety distance and the equipment installation distance of the embodiment are designed to be 3.3m, and the electrification safety requirement is met.
Example 2: design and application method of electrified high-efficiency fire extinguishing device for certain 220kV outdoor unattended transformer at sea opening
1) According to a similar embodiment, the water mist voltage grade of a certain 220kV outdoor unattended transformer at the sea is 220kV, and due to the fact that a fixed fire extinguishing device is adopted for fire extinguishing and unattended operation, the safety requirement of preventing flashover, tripping and power failure between high-voltage bushings of the transformer or between the bushings to the ground is only required to be met.
2) The voltage class of the transformer is known to be 220kV, namely the highest endurance voltage is 220kV; the transformer is located in an area with an altitude of less than 150m, so that a standard atmospheric pressure of 101kPa is adopted; the conductivity of the adopted fire extinguishing water agent is 400 mus/cm; the electrode model adopts a spray head-high voltage sleeve model.
3) Carrying out a water mist insulation performance test; the fine water mist generating pump set generates fine water mist with adjustable droplet parameters; measuring the fog drop parameters by adopting PDPA; generating high voltage by adopting a power supply module; the atmospheric pressure is adjusted by an atmospheric pressure adjusting device, and the environmental temperature is controlled to be 20 ℃ and the humidity is controlled to be 50% by a temperature and humidity control system. And (3) simulating haze pollution by using a haze generating device, and coating the insulating sleeve with a coating method to form dirt. Breakdown voltage test of the test the water mist breakdown voltage value was measured using a 50% withstand voltage method. Simulating the haze pollution level and the high-voltage bushing pollution level of an application environment, carrying out initialization design on the electrified safety of water mist, and drawing a fog drop parameter interval graph and an electrified safety correction coefficient K value graph which accord with the electrified safety standard;
4) As the seaport belongs to the Chinese seaside city, the environmental pollution is light, the haze pollution level reaches 0-1 level, and the high-voltage bushing pollution level reaches 0-1 level, the fog drop parameter interval meeting the electrified safety requirement standard of the ground is Dv99:<399mm；Dv90：<615mm；SMD：&868mm; fog drop concentration:<10g/m 2 s; three-dimensional speed of fog drops:&10m/s; k value: 0.99.
5) Aiming at the specific type of fire, a fire simulation test is carried out to obtain the diameter optimization parameters of the fog drops, which can realize the electrified high-efficiency fire extinguishing. The transformer oil fire is a B-type fire, and the transformer fire is simulated by using an oil fire model. The outdoor power transformer fire belongs to outdoor fire, so that a windy working condition is simulated. The design wind speed in the seaport area is 5 grades, and meets the annual large wind power level of the seaport area. And obtaining the relation between the simulated fire extinguishing efficiency and the fog drop parameters. In the droplet diameter parameter section which is obtained in the previous step and can be applied to charged fire extinguishing, the droplet diameter parameter of the charged efficient fire extinguishing of the water mist is optimally selected, so that the water mist has the charged fire extinguishing performance and the efficient fire extinguishing performance at the same time, and the parameters are as follows: dv99:310mm; dv90:580mm; SMD:641mm; fog drop concentration: 9g/m 2 S; three-dimensional speed of fog drops: 8-9m/s; .
5) The diameter optimization parameters of the droplets of the electrified and efficient water mist fire extinguishing device obtained by the design are utilized to comprehensively design the electrified water mist fire extinguishing device, and the electrified water mist fire extinguishing device comprises a water mist spray head, a device pressure system, a pipeline transmission system and an automatic electrified fire extinguishing system. The specific design process is as follows:
(1) and designing a water mist spray head. By adjusting the spray head KCoefficient, pressure, flow value, and design nozzle droplet parameters basically accord with the design parameters. Single nozzle flow q i Calculated according to the following formula:
calculating to obtain the flow q of a single spray head i ＝12L/min。
(2) And (4) designing a pipeline transmission system. The 60 nozzle design is used, therefore, the total flow design of the pipeline is calculated according to the following formula:
calculated Q =720L/min.
The design requirement according to the pipeline diameter is as follows: the flow rate of the liquid in the pipe is preferably less than 5m/s, and the pipe diameter is selected to be 80mm. The pipeline material is stainless steel pipe.
(3) And designing a pressure system of the device. The supply pressure of the fire-extinguishing installation is calculated using the following formula:
H＝∑h+P 0 +h z
where, Σ h = h g (pipeline head loss) + h f (local head loss of valves, pipes, etc.) in which: h is the supply pressure (MPa) of the water pump lift or the system inlet, and the local head loss H of equipment valves, pipe fittings and the like f Calculating by using data explained in the current national standard GB 50084 and GB 50219, and obtaining sigma h =2MPa;
P 0 the working pressure of the most unfavorable water mist spraying point is set as the highest pressure of the equipment of 6MPa; h is z The lift difference between the spraying point of the least favorable water mist and the central line of the lowest water mist or the horizontal water supply inlet pipe of the system is 5MPa.
Finally, the water pump lift or the supply pressure H =6+5+2=13MPa at the system inlet is obtained through calculation. This value is the head pressure required for the equipment design. The pressure system selects a plunger pump as the pressure pump group.
(4) The automatic induction fire extinguishing of the fire extinguishing device is controlled, and the electrified high-efficiency fire extinguishing is realized.
6) According to the electrified safety correction coefficient K value diagram, parameters of water mist discharge distance and equipment installation distance are designed, and the electrified safety requirement is guaranteed. The charged safety distance under 220kV air is 3.0m. Therefore, according to the K value of 0.99 obtained above, the water mist electrification safety distance and the equipment installation distance of the embodiment are designed to be 3.0m, and the electrification safety requirement is met.
Claims (9)
1. A design method of a water mist electrified fire extinguishing device for a power transformer fire disaster comprises the following steps:
s1, preliminarily designing parameters of water mist according to the safety requirement of charged fire extinguishing;
s2, according to the water mist parameters designed in the step S1, carrying out a fire simulation fire extinguishing test aiming at the specific type of the power transformer fire, and thus optimizing the preliminarily designed water mist parameters;
s3, designing a water mist electrified fire extinguishing device of the power transformer according to the water mist parameters optimized in the step S2;
s4, designing the discharge distance of the water mist to the electrified end in the power transformer, thereby ensuring the safety of electrified fire extinguishing.
2. The design method of the mist charged fire extinguisher for power transformer fire according to claim 1 is characterized by the safety requirements of step S1, specifically to prevent the flashover trip outage between the high voltage bushings or bushing to ground of the power transformer.
3. The design method of the water mist electrified fire extinguishing device aiming at the power transformer fire is characterized in that the safety requirement is that the breakdown field intensity of the water mist in the breakdown flashover phenomenon is not less than 0.9 times of the breakdown field intensity of the air in the breakdown flashover phenomenon under the same condition.
4. The design method of the mist fire extinguisher for power transformer fire according to claim 3, characterized in that the maximum withstand voltage is the rated voltage of the power transformer; the electrode model adopts a spray head-high voltage bushing model; the atmospheric pressure is selected by adopting the following principle: the atmospheric pressure of the area below the altitude of 2000m is selected to be 101kPa, and the atmospheric pressure of the area above the altitude of 2000m is selected to be 80kPa; the temperature of the atmosphere is fixed to be 20 ℃, and the humidity of the atmosphere is fixed to be 50%; the haze pollution grade adopts a three-level haze pollution grade specified by the national standard, and the high-voltage bushing pollution grade adopts a five-level pollution grade specified by the national standard.
5. The design method of the water mist electrified fire extinguishing device aiming at the power transformer fire disaster is characterized in that the parameters of the water mist are preliminarily designed according to the safety requirement of electrified fire extinguishing in the step S1, and specifically, the parameters of the water mist are preliminarily designed by simulating the haze pollution level and the high-pressure sleeve pollution level in the power transformer application environment according to the highest withstand voltage, the water agent conductivity, the atmospheric pressure and the electrode model.
6. The design method of the mist charged fire extinguisher for power transformer fire according to the claim 5, characterized in that the parameters of the mist in the step S1 are preliminarily designed, specifically, the parameters of the mist droplets include the volume characteristic diameter, the Sortell average particle diameter, the concentration of the mist droplets and the three-dimensional velocity of the mist droplets.
7. The method according to claim 6, wherein the specific type of the power transformer fire is determined by the following rules: determining the fire type of the power transformer as B-type oil fire; the simulated combustion material of the fire adopts 25# or 40# paraffin-based transformer oil or naphthenic transformer oil.
8. The method according to claim 7, wherein the step S3 is carried out to design the electrified water mist fire extinguisher of the power transformer, and specifically comprises the following steps:
A. designing a water mist spray head according to the following formula:
in the formula q i The flow rate of a single spray head, K is the flow coefficient of the spray head, and P is the designed working pressure of the spray head;
B. the pipeline transmission system is designed according to the following formula:
wherein Q is the design flow of the fire extinguishing device, n is the total number of the spray heads, and Q is i The flow of the ith nozzle, wherein i is a natural number;
C. the pressure system design is carried out according to the following formula:
H＝∑h+P 0 +h z
where H is the supply pressure at the pump head or system inlet, and Σ H is the accumulated value of the loss of water head along the pipeline and local head, P 0 Working pressure of the most unfavorable spray point, h z The lift difference between the spraying point of the least favorable water mist and the central line of the lowest water mist or system horizontal water supply inlet pipe is obtained;
wherein the pipeline on-way and local head loss comprises pipeline head loss, equipment valve head loss and pipe fitting local head loss;
the pipeline head loss is calculated by adopting the following formula:
in the formula h g F is friction resistance loss, f is a friction coefficient, L is the length of the pipeline, rho is liquid density, Q is flow, and d is the diameter of the pipeline;
the friction coefficient f is obtained by inquiring a Modi diagram according to the Reynolds number; the Reynolds number is calculated by the following formula:
in the formula, re is Reynolds number, mu is absolute dynamic viscosity;
D. and designing a control system of the automatic fire extinguishing device so as to realize automatic fire extinguishing.
9. The method for designing a mist fire extinguisher according to claim 8, wherein the discharge distance of the charged end is designed in step S4, specifically, the following principles are adopted: dividing the safe distance of the existing power equipment by the electrified safe correction coefficient to obtain the safe distance under the water mist environment, and designing the water mist discharge distance according to the safe distance under the water mist environment; the electrified safety correction coefficient is defined as the ratio of the breakdown voltage of the water mist to the breakdown voltage of the air under the same condition.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU622471A1 (en) * | 1977-02-15 | 1978-09-05 | Всесоюзный научно-исследовательский институт противопожарной обороны | Powder-type fire extinguisher |
| CN204655840U (en) * | 2015-05-19 | 2015-09-23 | 湖南省湘电试研技术有限公司 | The high-lift live-wire fire fighting device of electrical network mountain fire |
| CN106680016A (en) * | 2017-03-10 | 2017-05-17 | 国网湖南省电力公司 | Method and device for testing water spray insulated electrified extinguishment |
| CN106880916A (en) * | 2017-02-24 | 2017-06-23 | 湖南省湘电试研技术有限公司 | A kind of powered high-lift fire extinguishing equipment Design method of transmission line forest fire |
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2017
- 2017-10-24 CN CN201711001703.6A patent/CN107737430B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU622471A1 (en) * | 1977-02-15 | 1978-09-05 | Всесоюзный научно-исследовательский институт противопожарной обороны | Powder-type fire extinguisher |
| CN204655840U (en) * | 2015-05-19 | 2015-09-23 | 湖南省湘电试研技术有限公司 | The high-lift live-wire fire fighting device of electrical network mountain fire |
| CN106880916A (en) * | 2017-02-24 | 2017-06-23 | 湖南省湘电试研技术有限公司 | A kind of powered high-lift fire extinguishing equipment Design method of transmission line forest fire |
| CN106680016A (en) * | 2017-03-10 | 2017-05-17 | 国网湖南省电力公司 | Method and device for testing water spray insulated electrified extinguishment |
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