CN112494852A - Overhead fire insulation method and device for preventing extra-high voltage converter transformer fire from expanding - Google Patents

Overhead fire insulation method and device for preventing extra-high voltage converter transformer fire from expanding Download PDF

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CN112494852A
CN112494852A CN202011094101.1A CN202011094101A CN112494852A CN 112494852 A CN112494852 A CN 112494852A CN 202011094101 A CN202011094101 A CN 202011094101A CN 112494852 A CN112494852 A CN 112494852A
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oil
transformer
layer
fire
pit
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CN112494852B (en
Inventor
黄玉彪
张佳庆
黄勇
李金忠
王庆
张民
谭静
王刘芳
程登峰
田宇
柯艳国
罗沙
谢佳
范明豪
李伟
过羿
尚峰举
刘睿
苏文
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Anhui Electric Power Co Ltd
State Grid Economic and Technological Research Institute
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State Grid Corp of China SGCC
Electric Power Research Institute of State Grid Anhui Electric Power Co Ltd
State Grid Economic and Technological Research Institute
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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
    • A—HUMAN NECESSITIES
    • A62—LIFE-SAVING; FIRE-FIGHTING
    • A62C—FIRE-FIGHTING
    • A62C31/00—Delivery of fire-extinguishing material
    • A62C31/02—Nozzles specially adapted for fire-extinguishing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/08—Cooling; Ventilating
    • H01F27/10—Liquid cooling
    • H01F27/16—Water cooling

Abstract

The invention discloses an overhead fire insulation method and device for avoiding the expansion of an extra-high voltage converter transformer fire, wherein the method is applied to the overhead fire insulation device for avoiding the expansion of the extra-high voltage converter transformer fire, and comprises the following steps: acquiring the infiltration time of the transformer oil in the oil pit, and acquiring the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit according to the infiltration time of the transformer oil in the oil pit; acquiring the heat release quantity of the transformer oil; acquiring the heat absorption capacity of the cobble layer; obtaining a relational expression of the thickness of the critical cobblestone layer and the overflow flow of the transformer oil and a relational expression of the thickness of the critical cobblestone layer and the overflow time of the transformer oil; obtaining the minimum thickness and the maximum thickness of the cobblestone layer, and setting the thickness of the cobblestone layer within the thickness range of the cobblestone layer so as to achieve the best fire extinguishing effect; the invention has the advantages that: the optimal fire insulation effect is realized, the oil pit below the cobblestones is ensured not to be ignited, and the hidden danger of fire hazard is avoided.

Description

Overhead fire insulation method and device for preventing extra-high voltage converter transformer fire from expanding
Technical Field
The invention relates to the technical field of fire fighting, in particular to an overhead fire insulation method and device for avoiding the expansion of an extra-high voltage converter transformer fire.
Background
The transformer belongs to large-scale oil-containing equipment, and a single transformer contains about 200 tons of oil. Once a fire occurs, a large-scale fire spreading phenomenon may be caused. In order to reduce the fire scale of transformer oil, an oil pit is generally arranged under a transformer and is connected with a remote accident oil pool through an accident oil discharge pipeline, and the development of fire is effectively inhibited in a mode of reducing combustibles in a fire area. In order to prevent the transformer oil flowing into the oil pit from being continuously combusted, a cobble layer is arranged inside the oil pit and used for isolating fire.
The existing cobble layer is generally laid on the ground. However, several accidents in recent years have shown that the floor-type laying scheme has its limitations, and cannot rapidly discharge a large amount of transformer oil in a short time, and in order to rapidly discharge the transformer oil, an overhead laying scheme has appeared, for example, chinese patent publication No. CN209249235U, which discloses an on-site automatic oil discharge device for a transformer, comprising: the transformer comprises a first valve communicated with a transformer body, an oil discharge pipeline with one end communicated with the first valve, and an oil storage pool below the transformer body, wherein the other end of the oil discharge pipeline is communicated with the oil storage pool; the electric valve or the electromagnetic valve is arranged on the oil discharge pipeline and is used for controlling the on-off of the oil discharge pipeline; and the vacuumizing device is arranged between the first valve and the electric valve or the electromagnetic valve, is communicated with the oil discharge pipeline through a second valve, and is used for controlling the on-off between the vacuumizing device and the oil discharge pipeline. A base is arranged between the lower side of the transformer body and the ground, a cobble layer is arranged on the periphery of the base, and the cobble layer is arranged on the ground on the upper side of the oil storage pool. Meanwhile, a certain height distance is reserved between the transformer body and the ground, namely between the transformer body and the surrounding cobblestone layers. The utility model discloses a though set up cobblestone built on stilts device and separate the fire, it has following problem nevertheless: 1. the critical conditions for the lower part of the pebble layer to be ignited due to different overhead conditions (pebble thickness, overhead height) are not yet clear; 2. the overhead laying is beneficial to discharging transformer oil, but the lower space is easy to burn, the fire risk exists in the accident pipeline, and how to avoid the fire is not given.
In summary, the conventional converter transformer overhead fire insulation method and device cannot achieve the optimal fire insulation effect, cannot ensure that an oil pit below cobblestones cannot be ignited, and have fire hazard.
Disclosure of Invention
The invention aims to solve the technical problems that the method and the device for preventing the expansion of the fire of the extra-high voltage converter transformer in the prior art cannot realize the optimal fire insulation effect, cannot ensure that an oil pit below cobblestones cannot be ignited, and have fire hazard.
The invention solves the technical problems through the following technical means: the utility model provides an avoid extra-high voltage converter transformer conflagration to enlarge built on stilts fire insulation method, is applied to and avoids extra-high voltage converter transformer conflagration to enlarge built on stilts fire insulation device, fire insulation device includes transformer, oil pit, cobblestone layer and supporting layer, set up the supporting layer in the oil pit, lay the cobblestone layer above the supporting layer, place the transformer above the cobblestone layer, the method includes:
the method comprises the following steps: obtaining the infiltration time of the transformer oil in the oil pit;
step two: obtaining the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit according to the infiltration time of the transformer oil in the oil pit;
step three: and obtaining the heat transfer critical heat insulation time of the cobblestone layer and the critical thickness of the cobblestone layer.
The thickness of the cobble layer is set, so that the cobble layer does not penetrate and catch fire within the thickness range, certain fire insulation capability can be realized under the condition of meeting the requirement of oil discharge, the optimal fire insulation effect is realized, an oil pit below cobbles is ensured not to be ignited, and fire hazard is avoided.
Further, the first step comprises:
by the formula
Figure BDA0002723099110000031
Obtaining the infiltration time of the transformer oil in the oil pit, wherein t is the time required for the transformer oil to infiltrate to the bottom of the oil pit through the upper surface of the oil pit, and hStone (stone)Laying thickness v for cobble layer in oil pitOilThe infiltration speed of the transformer oil in the cobble layer, H is the oil pit depth, gHeavy loadIs the acceleration of gravity.
Further, the second step comprises:
according to the infiltration time of the transformer oil in the oil pit, the formula is adopted
Figure BDA0002723099110000032
Obtaining the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit, wherein QFaceThe critical flow rate is that the transformer oil does not overflow after flowing into the oil pit, lambda is the permeability of the cobblestone layer, S1Is the total surface area of the oil sump, S2Occupying area for equipment in the oil pit.
Further, the third step includes:
step 301: acquiring the heat release quantity of the transformer oil;
step 302: acquiring the heat absorption capacity of the cobble layer;
step 303: obtaining a relational expression of the thickness of the critical cobblestone layer and the overflow flow of the transformer oil and a relational expression of the thickness of the critical cobblestone layer and the overflow time of the transformer oil;
step 304: the minimum thickness and the maximum thickness of the cobblestone layer are obtained, and the thickness of the cobblestone layer is set within the thickness range of the cobblestone layer, so that the optimal fire extinguishing effect is achieved.
Still further, the step 301 includes: by the formula mOil＝vOilρOiltOilAcquiring the quality of the transformer oil overflowing to the cobblestone layer, wherein vOilIs the overflow rate per unit time, rho, of the transformer oilOilIs the transformer oil density, tOilThe overflow time of the transformer oil;
according to the quality of the transformer oil overflowing to the cobble layer, the formula Q is usedOil＝mOilcP oil(TOil 1-TOil 2) Obtaining the heat release of the transformer oil, wherein cP oilIs the constant pressure specific heat capacity, T, of the transformer oilOil 1For initial oil temperature of spilled transformer oil, TOil 2The temperature of the transformer oil after penetrating through the cobblestone layer.
Still further, the step 302 includes: :
by the formula mStone (stone)＝((a+l)(b+l)-ab)hStone (stone)(1-λ)ρStone (stone)Obtaining the quality of a cobblestone layer contacted with transformer oil, wherein a is the length of the transformer, b is the width of the transformer, l is the coverage width of the transformer oil overflowing to the surface of the cobblestone layer along the transformer body, and rho isStone (stone)The density of the cobble layer;
according to the quality of a cobble layer contacted with transformer oil, the quality of the cobble layer is determined by a formula QStone (stone)＝mStone (stone)cP stone(TStone 2-TStone 1) Obtaining the heat absorption capacity of the cobble layer, wherein cP stoneIs the constant pressure specific heat capacity of the cobble layer, TStone 2Is the temperature, T, of the transformer after heat absorptionStone 1The initial temperature of the cobbles.
Still further, the step 303 includes:
obtaining a relation formula between the thickness of the critical cobble layer and the overflow flow of the transformer oil according to the critical flow of the transformer oil which does not overflow after flowing into the oil pit, the heat release of the transformer oil and the heat absorption of the cobble layer as follows
Figure BDA0002723099110000041
Obtaining a relation between the thickness of the critical cobble layer and the overflow time of the transformer oil according to the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit, the heat release of the transformer oil and the heat absorption of the cobble layer as follows
Figure BDA0002723099110000042
Still further, the step 304 includes:
the critical condition of the minimum thickness of the cobble layer without penetrating and firing is tOilThe total oil amount overflowing in time is equal to all the transformer oil in the transformer body, so the minimum thickness of the cobblestone layer is
Figure BDA0002723099110000051
In order to ensure that the transformer can be smoothly discharged from the cobblestone layer, the shortest time for the cobblestone layer to penetrate and catch fire is longer than the time required for the transformer oil in the transformer to overflow or discharge, namely tFruit of Chinese wolfberry≥tOilWherein, tFruit of Chinese wolfberryThe actual required time for the transformer oil to completely overflow from the transformer body is calculated
Figure BDA0002723099110000052
So that the maximum thickness of the cobble layer is
Figure BDA0002723099110000053
The invention also provides a device using the transformer fire insulation method, which comprises a transformer, an oil pit, a cobble layer, a plurality of support columns and a support layer, wherein the support layer is arranged in the oil pit, the cobble layer is laid above the support layer, the transformer is placed above the cobble layer, the bottoms of the support columns are fixed at the bottom of the oil pit, the tops of the support columns sequentially penetrate through the support layer and the cobble layer and are fixed at the bottom of the transformer, a gap is formed between the support layer and the bottom of the oil pit, and the bottom of the oil pit is communicated with an accident oil pool through a pipeline.
Furthermore, a plurality of water spray nozzles are arranged in the oil pit, and the spray range of the plurality of water spray nozzles covers all areas of the bottom of the oil pit.
Further, the cobble layer is cobbles.
Further, the supporting layer is a steel wire mesh.
The invention has the advantages that:
(1) the thickness of the cobble layer is set, so that the cobble layer does not penetrate and catch fire within the thickness range, certain fire insulation capability can be realized under the condition of meeting the requirement of oil discharge, the optimal fire insulation effect is realized, an oil pit below cobbles is ensured not to be ignited, and fire hazard is avoided.
(2) The transformer fire-insulating device is characterized in that the oil pit is internally provided with a water spray nozzle, the lower part of the cobblestone is provided with a water spray fire-extinguishing system, so that the transformer oil seeped to the bottom of the oil pit can be extinguished and cooled, the risk of ignition of the oil pit is reduced to the maximum extent, the transformer oil entering the accident oil discharge pipeline is prevented from being exposed to the fire, other adjacent converter transformers are prevented from being ignited, meanwhile, the fire-extinguishing medium is selected from water spray with good fluidity and relatively small flow, and the transformer oil and the water spray can be quickly discharged.
Drawings
FIG. 1 is a flow chart of an overhead fire insulation method for avoiding the expansion of an ultra-high voltage converter transformer fire in the embodiment 1 of the invention;
fig. 2 is a schematic structural diagram of an overhead fire-insulating device for preventing an extra-high voltage converter transformer fire from expanding in embodiment 2 of the invention;
FIG. 3 is a graph showing the relationship between the thickness of cobblestones and the infiltration time of a transformer in an overhead fire barrier apparatus for preventing the fire from spreading due to an extra-high voltage converter transformer, which is disclosed in embodiment 2 of the present invention;
fig. 4 is a graph showing a relationship between a thickness of a cobble layer and a critical overflow rate in an overhead fire barrier apparatus for preventing an extra-high voltage converter from fire expansion, which is disclosed in embodiment 2 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
As shown in fig. 1 and 2, an overhead fire insulation method for preventing an extra-high voltage converter transformer fire from expanding is applied to an overhead fire insulation device for preventing an extra-high voltage converter transformer fire from expanding, the fire insulation device comprises a transformer 1, an oil pit 2, a cobble layer 3 and a supporting layer 5, a supporting layer 5 is arranged in the oil pit 2, a cobble layer 3 is laid above the supporting layer 5, and the transformer 1 is placed above the cobble layer 3, and the method comprises the following steps:
step S1: acquiring the infiltration time of transformer oil in the oil pit 2, and acquiring the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit 2 according to the infiltration time of the transformer oil in the oil pit 2, wherein the transformer oil refers to the oil in the transformer 1, and for convenience of description, the transformer oil is completely called as transformer oil in the application; the specific process is as follows:
by the formula
Figure BDA0002723099110000071
Obtaining the infiltration time of the transformer oil in the oil pit 2, wherein tThe time required for the transformer oil to seep down to the bottom of the oil pit 2 through the upper surface of the oil pit 2, hStone (stone)The thickness v is laid for the cobble layer 3 in the oil pit 2OilThe infiltration speed of the transformer oil in the cobble layer 3, H is the depth of the oil pit 2, gHeavy loadIs the acceleration of gravity;
step S2, obtaining the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit, and the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit 2
Figure BDA0002723099110000072
Wherein, VPoolIs the effective oil-holding volume of the oil pit 2, and VPool＝λ*(S1-S2)hStone (stone)+(S1-S2)(H-hStone (stone)) Therefore, it is
Figure BDA0002723099110000073
Wherein Q isFaceThe critical flow rate of the transformer oil which does not overflow after flowing into the oil pit 2, lambda is the permeability of the cobble layer 3, S1Is the total surface area of the oil sump 2, S2Occupying area for equipment in the oil pit 2.
Step S3: obtaining the heat transfer critical heat insulation time of the cobblestone layer and the critical thickness of the cobblestone layer;
first, step 301: acquiring the heat release quantity of the transformer oil; the critical ignition of the cobblestone layer is determined according to the fact that the heat release amount of the transformer oil is equal to the heat absorption amount of cobblestones, at the moment, the temperature of the transformer oil penetrating through the bottom of the cobblestone layer is the flash point temperature (138 ℃) of the transformer 1, and the cobblestone temperature is increased from the normal temperature to the flash point temperature (138 ℃) of the transformer oil.
By the formula mOil＝vOilρOiltOilObtaining the quality of the transformer oil overflowing to the cobblestone layer 3, wherein vOilIs the overflow rate per unit time, rho, of the transformer oilOilIs the transformer oil density, tOilThe overflow time of the transformer oil;
according to the quality of the transformer oil overflowing to the cobblestone layer 3, the formula Q is adoptedOil＝mOilcP oil(TOil 1-TOil 2) Obtaining a transformationHeat release of the oil, whereinP oilIs the constant pressure specific heat capacity, T, of the transformer oilOil 1For initial oil temperature of spilled transformer oil, TOil 2The temperature of the transformer oil after penetrating the cobble layer 3.
Next, step 302: acquiring the heat absorption capacity of the cobble layer; the specific process is as follows:
by the formula mStone (stone)＝((a+l)(b+l)-ab)hStone (stone)(1-λ)ρStone (stone)Obtaining the mass of the cobble layer 3 contacted with the transformer oil, wherein a is the length of the transformer 1, b is the width of the transformer 1, l is the coverage width of the transformer oil overflowing to the surface of the cobble layer 3 along the body of the transformer 1, and rho isStone (stone)The density of the cobble layer 3;
according to the quality of the cobble layer 3 contacted with the transformer oil, the formula Q is passedStone (stone)＝mStone (stone)cP stone(TStone 2-TStone 1) Obtaining the heat absorption capacity of the cobble layer, wherein cP stoneIs the constant pressure specific heat capacity, T, of the cobble layer 3Stone 2Is the temperature, T, of the transformer 1 after heat absorptionStone 1The initial temperature of the cobbles.
Then, step 303: obtaining a relational expression of the thickness of the critical cobble layer 3 and the overflow flow of the transformer oil and a relational expression of the thickness of the critical cobble layer 3 and the overflow time of the transformer oil; the specific process is as follows:
according to the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit 2, the heat release quantity of the transformer oil and the heat absorption quantity of the cobble layer, the relation between the thickness of the critical cobble layer 3 and the overflow flow rate of the transformer oil is obtained as follows
Figure BDA0002723099110000081
According to the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit 2, the heat release quantity of the transformer oil and the heat absorption quantity of the cobble layer, the relation between the thickness of the critical cobble layer 3 and the overflow time of the transformer oil is obtained as follows
Figure BDA0002723099110000091
Finally, step 304: obtain 3 minimum thickness and the maximum thickness of cobble layer, set up its thickness in 3 thickness ranges on cobble layer to reach best fire control effect, concrete process is:
the critical condition of the minimum thickness of the cobble layer 3 without penetrating and firing is tOilThe total amount of oil overflowing in time is equal to the total transformer oil in the transformer 1, so the minimum thickness of the cobblestone layer 3 is
Figure BDA0002723099110000092
In order to ensure that the transformer 1 can be smoothly discharged from the cobble layer 3, the shortest time for the cobble layer 3 to be penetrated and ignited is longer than the time required for the transformer oil in the transformer 1 to overflow or be discharged, i.e. tFruit of Chinese wolfberry≥tOilWherein, tFruit of Chinese wolfberryThe actual required time for the transformer oil to completely overflow from the transformer 1 body is
Figure BDA0002723099110000093
So that the maximum thickness of the pebble layer 3 is
Figure BDA0002723099110000094
Through the technical scheme, the thickness of the cobble layer 3 is set in the embodiment 1 of the invention, so that the cobble layer 3 does not penetrate and catch fire within the thickness range, certain fire insulation capability can be realized under the condition of meeting the requirement of oil discharge, the optimal fire insulation effect is realized, the oil pit 2 below the cobbles is ensured not to be ignited, and the fire hazard is avoided.
Example 2
As shown in fig. 2, the transformer fire insulation device comprises a transformer 1, an oil pit 2, a cobble layer 3, a plurality of support columns 4 and a support layer 5, wherein the cobble layer 3 is cobbles. And a supporting layer 5 is arranged in the oil pit 2, and the supporting layer 5 is a steel wire mesh. Cobblestones are laid above the supporting layer 5, the transformer 1 is placed above the cobblestones, the bottoms of the supporting columns 4 are fixed to the bottom of the oil pit 2, the tops of the supporting columns 4 sequentially penetrate through the supporting layer 5 and the cobblestones to be fixed to the bottom of the transformer 1, a gap is formed between the supporting layer 5 and the bottom of the oil pit 2, the bottom of the oil pit 2 is communicated with an accident oil pool through a pipeline, and the thickness of the cobblestones is set by using the fire insulation method disclosed in embodiment 1, so that the cobblestones do not penetrate and catch fire within the thickness range.
After the transformer oil seeps into the oil pit 2 through the cobblestone layer, the transformer oil is discharged to a general accident oil pool (not shown) through an accident oil discharge pipeline. Since the accident pipe 7 is connected with 6 transformers 1 of the single valve bank, there is a risk that other 5 converter transformers of the valve bank are ignited and catch fire, and therefore, it is further ensured that no open fire occurs before transformer oil enters the accident pipe 7. In order to improve the fire insulation and extinguishing capabilities of the cobblestone overhead system, a fire extinguishing system under the cobblestone overhead laying condition is provided for extinguishing fire.
The fire extinguishing system fire extinguishing apparatus of the cobblestone overhead scheme mainly includes two parts: the first part is the complete setting of putting out a fire below the cobble layer, specifically sets up to: a plurality of water spray nozzles 6 are arranged in the oil pit 2, and the spray range of the water spray nozzles 6 covers all areas of the bottom of the oil pit 2. The second part is a local fire extinguishing enhancement measure of an accident oil drain pipeline port. The fire extinguishing medium is water spray with good fluidity and relatively small flow, and the transformer oil and the water spray can be quickly discharged. The whole water spray fire extinguishing system under the cobblestones can realize the functions of extinguishing and cooling transformer oil seeping downwards to the bottom of the oil pit 2, and the risk of catching fire of the oil pit 2 is reduced to the maximum extent. The local reinforcement measure of the accident oil discharge port is mainly to ensure that the transformer oil entering the accident oil discharge pipeline has no open fire, and protect the risk of other converter transformers catching fire.
Because the liquid reserved in the oil pit 2 has the risk of overflowing, the overflow flow risk of the transformer oil needs to be considered simultaneously on the basis of ensuring the fire extinguishing efficiency of the flow of the water spray fire extinguishing system, namely the flow of the water spray needs to meet the formula VWater (W)≤QFace-VOil。
The working process of embodiment 2 of the present invention is described below by way of specific examples:
taking a certain converter station as an example, the volume of single transformer oil is 155.6m3, and the volume of the single transformer oil is 140 t; the total area of the oil pit 2 is 176.5m2, wherein the occupied area of the equipment base is 82.5m 2; the porosity of the pebble layer is calculated according to 25 percent; according to the American standard NFPA850, the flow velocity of the transformer oil is 0.0817m/s through cobblestone layer; the depth of the foundation pit is 1.25 m. According to the formula
Figure BDA0002723099110000111
The time distribution required for the transformer oil to flow from the upper surface of the pebble layer to the bottom of the oil pit 2 through the pebble layers with different thicknesses can be obtained, as shown in fig. 3. It is obvious that the larger the thickness of the cobblestone layer is, the longer the time required for the transformer oil to seep to the bottom of the oil pit 2 is, and the greater the risk that the transformer oil is accumulated and spilled in the oil pit 2 is.
Combined type
Figure BDA0002723099110000112
And VPool＝λ*(S1-S2)hStone (stone)+(S1-S2)(H-hStone (stone)) The critical flow rate of the transformer oil overflowing from the body when the oil pit 2 overflows critically can be obtained, as shown in fig. 4. It can be seen from the figure that the smaller the thickness of the cobblestones, the greater the critical flow rate at which spillage occurs and the less the risk of transformer oil spilling from the oil sump 2. In general, the smaller the thickness of the cobblestones is, the more beneficial the fire accident oil discharge is, and the greater the probability of fire risk of the oil pit 2 is.
To ensure the fire-insulating capability of the cobble layer before all the transformer oil is discharged smoothly, the method is as follows
Figure BDA0002723099110000113
The critical minimum cobble thickness obtained is 0.76 m.
According to the formula
Figure BDA0002723099110000114
The thickness of different cobblestone layers and all transformer oil can be obtained and discharged from the oil pit 2The time relationship of (a) is shown in Table 1.
TABLE 1 Table of the relationship between the thickness of different cobble layers and the time of discharging all transformer oil from the oil sump 2
Figure BDA0002723099110000121
According to the formula
Figure BDA0002723099110000122
The thickness of the obtained cobble layer is less than 0.875 m.
The thickness range of the cobblestone layer is the best range from 0.76m to 0.875m, which can ensure the smooth discharge of the transformer oil and the fire-proof capability of the cobblestone layer in the whole oil discharge process.
Through the technical scheme, in the embodiment 2 of the invention, the cobblestones are arranged between the transformer 1 and the oil pit 2, and the cobblestones and the bottom of the oil pit 2 are provided with gaps, so that overhead arrangement is realized, a large amount of transformer oil can be rapidly discharged in a short time, the overhead arrangement can increase the ignition risk of the oil pit 2 and an accident oil discharge pipeline, in order to avoid ignition caused by overhead arrangement, the thickness of the cobblestones is set, the cobblestones do not penetrate and ignite in the thickness range, certain fire insulation capability can be realized under the condition of meeting the oil discharge requirement, the optimal fire insulation effect is realized, the oil pit 2 below the cobblestones is not ignited, and the fire hazard is avoided.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (12)

1. The utility model provides an avoid built on stilts fire insulation method that extra-high voltage converter changes conflagration to enlarge which characterized in that, is applied to and avoids built on stilts fire insulation device that extra-high voltage converter changes conflagration to enlarge, fire insulation device includes transformer, oil pit, cobblestone layer and supporting layer, set up the supporting layer in the oil pit, lay the cobblestone layer above the supporting layer, place the transformer above the cobblestone layer, the method includes:
the method comprises the following steps: obtaining the infiltration time of the transformer oil in the oil pit;
step two: obtaining the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit according to the infiltration time of the transformer oil in the oil pit;
step three: and obtaining the heat transfer critical heat insulation time of the cobblestone layer and the critical thickness of the cobblestone layer.
2. The method for preventing the expansion of the ultra-high voltage converter transformer fire disaster as claimed in claim 1, wherein the first step comprises:
by the formula
Figure FDA0002723099100000011
Obtaining the infiltration time of the transformer oil in the oil pit, wherein t is the time required for the transformer oil to infiltrate to the bottom of the oil pit through the upper surface of the oil pit, and hStone (stone)Laying thickness v for cobble layer in oil pitOilThe infiltration speed of the transformer oil in the cobble layer, H is the oil pit depth, gHeavy loadIs the acceleration of gravity.
3. The method for preventing the expansion of the ultra-high voltage converter transformer fire disaster as claimed in claim 1, wherein the second step comprises:
according to the infiltration time of the transformer oil in the oil pit, the formula is adopted
Figure FDA0002723099100000012
Obtaining the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit, wherein QFaceThe critical flow rate is that the transformer oil does not overflow after flowing into the oil pit, lambda is the permeability of the cobblestone layer, S1Is an oil pit assemblySurface area, S2Occupying area for equipment in the oil pit.
4. The method for preventing the expansion of the ultra-high voltage converter transformer fire disaster as claimed in claim 1, wherein the third step comprises:
step 301: acquiring the heat release quantity of the transformer oil;
step 302: acquiring the heat absorption capacity of the cobble layer;
step 303: obtaining a relational expression of the thickness of the critical cobblestone layer and the overflow flow of the transformer oil and a relational expression of the thickness of the critical cobblestone layer and the overflow time of the transformer oil;
step 304: the minimum thickness and the maximum thickness of the cobblestone layer are obtained, and the thickness of the cobblestone layer is set within the thickness range of the cobblestone layer, so that the optimal fire extinguishing effect is achieved.
5. The method for preventing the expansion of the EHV converter transformer fire according to claim 4, wherein the step 301 comprises:
by the formula mOil＝vOilρOiltOilAcquiring the quality of the transformer oil overflowing to the cobblestone layer, wherein vOilIs the overflow rate per unit time, rho, of the transformer oilOilIs the transformer oil density, tOilThe overflow time of the transformer oil;
according to the quality of the transformer oil overflowing to the cobble layer, the formula Q is usedOil＝mOilcP oil(TOil 1-TOil 2) Obtaining the heat release of the transformer oil, wherein cP oilIs the constant pressure specific heat capacity, T, of the transformer oilOil 1For initial oil temperature of spilled transformer oil, TOil 2The temperature of the transformer oil after penetrating through the cobblestone layer.
6. The method of claim 4, wherein the step 302 comprises:
by the formula mStone (stone)＝((a+l)(b+l)-ab)hStone (stone)(1-λ)ρStone (stone)Obtaining the quality of a cobblestone layer contacted with transformer oil, wherein a is the length of the transformer, b is the width of the transformer, l is the coverage width of the transformer oil overflowing to the surface of the cobblestone layer along the transformer body, and rho isStone (stone)The density of the cobble layer;
according to the quality of a cobble layer contacted with transformer oil, the quality of the cobble layer is determined by a formula QStone (stone)＝mStone (stone)cP stone(TStone 2-TStone 1) Obtaining the heat absorption capacity of the cobble layer, wherein cP stoneIs the constant pressure specific heat capacity of the cobble layer, TStone 2Is the temperature, T, of the transformer after heat absorptionStone 1The initial temperature of the cobbles.
7. The method for preventing the expansion of the EHV converter transformer fire according to claim 4, wherein the step 303 comprises:
obtaining a relation formula between the thickness of the critical cobble layer and the overflow flow of the transformer oil according to the critical flow of the transformer oil which does not overflow after flowing into the oil pit, the heat release of the transformer oil and the heat absorption of the cobble layer as follows
Figure FDA0002723099100000031
Obtaining a relation between the thickness of the critical cobble layer and the overflow time of the transformer oil according to the critical flow rate of the transformer oil which does not overflow after flowing into the oil pit, the heat release of the transformer oil and the heat absorption of the cobble layer as follows
Figure FDA0002723099100000032
8. The method of claim 4, wherein the step 304 comprises:
the critical condition of the minimum thickness of the cobble layer without penetrating and firing is tOilThe total oil amount overflowing in time is equal to all the transformer oil in the transformer body, so the minimum thickness of the cobblestone layer is
Figure FDA0002723099100000033
In order to ensure that the transformer can be smoothly discharged from the cobblestone layer, the shortest time for the cobblestone layer to penetrate and catch fire is longer than the time required for the transformer oil in the transformer to overflow or discharge, namely tFruit of Chinese wolfberry≥tOilWherein, tFruit of Chinese wolfberryThe actual required time for the transformer oil to completely overflow from the transformer body is calculated
Figure FDA0002723099100000034
So that the maximum thickness of the cobble layer is
Figure FDA0002723099100000041
9. An apparatus for using the overhead fire insulation method for avoiding the fire expansion of the ultra-high voltage converter transformer according to any one of claims 1 to 8, which is characterized by comprising a transformer, an oil pit, a cobble layer, a plurality of supporting columns and a supporting layer, wherein the supporting layer is arranged in the oil pit, the cobble layer is laid above the supporting layer, the transformer is placed above the cobble layer, the bottoms of the supporting columns are fixed at the bottom of the oil pit, the tops of the supporting columns sequentially penetrate through the supporting layer and the cobble layer to be fixed at the bottom of the transformer, a gap is formed between the supporting layer and the bottom of the oil pit, and the bottom of the oil pit is communicated with an accident oil.
10. The overhead fire barrier for preventing the expansion of an EHV converter transformer fire disaster as claimed in claim 9, wherein a plurality of water spray nozzles are arranged in the oil pit, and the spraying range of the plurality of water spray nozzles covers all areas of the bottom of the oil pit.
11. An overhead fire insulation device for preventing fire of an extra-high voltage converter transformer from spreading according to claim 9, wherein the cobble layer is cobble.
12. The overhead fire insulation device for avoiding the expansion of the ultra-high voltage converter transformer fire disaster as claimed in claim 9, wherein the supporting layer is a steel wire mesh.
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CN104319669A (en) * 2014-10-30 2015-01-28 国网上海市电力公司 Transformer substation with spray cooling device
CN208093295U (en) * 2018-04-26 2018-11-13 湖南天跃电气有限公司 A kind of fire-type oil-immersed power transformer

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2383189Y (en) * 1999-07-02 2000-06-14 卢培铨 Current guide fire-proof device of oil immersed transformer
RU17759U1 (en) * 2001-01-26 2001-04-27 Закрытое акционерное общество "АРТСОК" EXPLOSION, FIRE AND FIRE FIGHTING PREVENTION SYSTEM
CN101202153A (en) * 2007-10-23 2008-06-18 上海宝钢工程技术有限公司 Foundation construction for installation of oil-immersed type transformer
CN201817818U (en) * 2010-06-22 2011-05-04 河南省电力公司南阳供电公司 Basic equipment for supporting main transformer
CN201883446U (en) * 2010-11-12 2011-06-29 河南省电力公司南阳供电公司 Stone pit foundation structure for main transformer
CN202081428U (en) * 2011-05-30 2011-12-21 内蒙古电力勘测设计院 Oil pit pebble bracket of transformer
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