CN114635738A - Fire extinguishing mine for inhibiting heating oxidation of coal in goaf and arrangement method thereof - Google Patents
Fire extinguishing mine for inhibiting heating oxidation of coal in goaf and arrangement method thereof Download PDFInfo
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- CN114635738A CN114635738A CN202210256633.3A CN202210256633A CN114635738A CN 114635738 A CN114635738 A CN 114635738A CN 202210256633 A CN202210256633 A CN 202210256633A CN 114635738 A CN114635738 A CN 114635738A
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
- E21F5/00—Means or methods for preventing, binding, depositing, or removing dust; Preventing explosions or fires
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- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62C—FIRE-FIGHTING
- A62C99/00—Subject matter not provided for in other groups of this subclass
- A62C99/0009—Methods of extinguishing or preventing the spread of fire by cooling down or suffocating the flames
- A62C99/0018—Methods of extinguishing or preventing the spread of fire by cooling down or suffocating the flames using gases or vapours that do not support combustion, e.g. steam, carbon dioxide
Abstract
The invention discloses a fire extinguishing mine for inhibiting heating oxidation of coal in a goaf and an arrangement method thereof, wherein the fire extinguishing mine comprises an inner shell, an inner heat insulation layer, an outer heat insulation layer, a three-way pipe, a pneumatic switch, a valve rod and a butterfly valve; wherein the inner shell is used for holding liquid nitrogen, interior heat preservation and outer heat preservation all play and reduce the heat exchange efficiency of inner shell and external, the inside external temperature of while of outer heat preservation rises the back gaseous atmospheric pressure that thermal expansion increases provides drive power for pneumatic switch's start-up, pneumatic switch passes through the valve rod and is connected with the butterfly valve in the tee bend pipe, when the piston rod pressurized removal in pneumatic switch, it can drive the valve rod and rotate, and then make the butterfly valve open, liquid nitrogen rapid gasification and spout around through the tee bend pipe in the inner shell this moment, make its coal that can be in the goaf heat up oxidation stage and cool down and prevent it from developing into the coal spontaneous combustion promptly, and need not to lay the pipeline from the goaf outside during the cooling, thereby avoided taking place by the condition that the waste rock of whereabouts pounded, finally guarantee the fire control effect to the goaf.
Description
Technical Field
The invention belongs to the technical field of spontaneous combustion prevention and control of coal in a goaf, and particularly relates to a fire extinguishing mine for inhibiting heating oxidation of coal in the goaf and an arrangement method thereof.
Background
The goaf is a space left after underground coal mine resource mining, and displacement, cracking, crushing and caving are caused by instability of surrounding rocks until the whole overlying strata sinks and bends to cause deformation and damage of the earth surface. In addition, a large amount of residual coal and gangue exist in the goaf, the residual coal in the goaf is contacted with oxygen to be oxidized and generate heat due to the mining of a coal mine, and when the heat generated by oxidation is accumulated to a certain temperature (namely, an oxidation temperature rise stage), a spontaneous combustion phenomenon can occur. In order to prevent underground coal resources from being lost and influence on safe production of coal, a reasonable solution is provided for the spontaneous combustion problem of the coal in the goaf.
At present, a plurality of technical measures exist for preventing and controlling spontaneous combustion of coal in a goaf, for example, the invention discloses a high-position drilling and grouting fire extinguishing technology for preventing and controlling spontaneous combustion of coal in the goaf, which is to construct drilling holes in a crossheading close to a spontaneous combustion area of the coal in the goaf and fill loess slurry into the goaf through the drilling holes so as to effectively control the range of a dangerous area of spontaneous combustion of the coal in the goaf and reduce the temperature of the dangerous area and the concentration of toxic and harmful gases; the Chinese patent with publication number CN110847948A discloses a fire prevention and extinguishing system injected with compound inert gas, which firstly analyzes CO2And N2The composite inert gas prepared by mixing in different proportions has the coal spontaneous combustion inhibiting effect on the coal quality of the spontaneous combustion ignition place of the goaf, the optimal mixing proportion of the composite inert gas is determined, and then the composite inert gas is injected into the crossheading through a gas transmission pipelineAnd in the pre-buried pipeline, the drilling holes among the racks and the drilling holes of the coal pillars, the all-dimensional coverage of the spontaneous combustion dangerous area of the coal in the goaf is realized.
The fire prevention and extinguishing technologies play a certain role in coal spontaneous combustion prevention and control of the goaf, but the fire extinguishing materials are input into the goaf on the working face through various transmission means, but the existing mining mines mostly mainly use large mines, the fire prevention and extinguishing technologies cannot completely cover the coal spontaneous combustion dangerous area of the whole goaf, and the fire extinguishing materials are generally injected into the goaf for fire extinguishing treatment after the coal spontaneous combustion temperature is higher than the critical temperature due to the external input mode, so that the fire extinguishing at the moment not only needs more fire prevention and extinguishing materials, but also greatly prolongs the fire extinguishing time. In addition, the exhaust pipeline laid in the goaf is easily broken by falling gangue, so that the transmission of fire prevention and extinguishing materials cannot be realized, and the fire extinguishing effect is finally lost. Therefore, how to provide a device and a method can reduce the temperature of the coal in the goaf in a temperature-rise oxidation stage to prevent the coal from developing into spontaneous combustion, and pipelines do not need to be laid outside the goaf during temperature reduction, so that the situation that the coal is smashed by falling gangue is avoided, and the fire prevention and extinguishing effect on the goaf is finally ensured.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a fire extinguishing mine for inhibiting heating oxidation of coal in a goaf and an arrangement method thereof, which can cool the coal in the goaf in a heating oxidation stage to prevent the coal from developing into spontaneous combustion, and pipelines do not need to be laid outside the goaf during cooling, so that the condition that the coal is smashed by falling waste rocks is avoided, and the fire extinguishing effect on the goaf is finally ensured.
In order to achieve the purpose, the invention adopts the technical scheme that: a fire extinguishing mine for inhibiting heating and oxidation of coal in a goaf comprises an inner shell, an inner heat insulation layer, an outer heat insulation layer, a three-way pipe, a pneumatic switch, a valve rod and a butterfly valve;
the inner heat-insulating layer is wrapped outside the inner shell, the outer heat-insulating layer is wrapped outside the inner heat-insulating layer and is a bag body, a certain amount of mixed gas is filled in the bag body, the three-way pipe is positioned above the inner shell and consists of an air inlet section and two air exhaust sections, and the air inlet section of the three-way pipe is communicated with the inner cavity of the inner shell; the inner shell is provided with a nitrogen injection hole which penetrates through the inner heat-insulating layer and the outer heat-insulating layer to enable the inner cavity of the inner shell to be communicated with the outside, liquid nitrogen is injected into the inner cavity of the inner shell through the nitrogen injection hole, and the nitrogen injection hole is sealed through a sealing plug;
the pneumatic switch comprises an air cylinder, two pistons, a piston rod, a pressure regulating spring and a crank, wherein the two pistons are respectively fixed at the two ends of the piston rod, the piston rod is positioned in the air cylinder, the two pistons are in sliding seal with the inner wall of the air cylinder, the pressure regulating spring is positioned in the air cylinder, one end of the pressure regulating spring is fixedly connected with the upper end of the air cylinder through a spring fixing seat, the other end of the pressure regulating spring is connected with one of the pistons of the piston rod, the air cylinder is vertically fixed at one side of an air inlet section of the three-way pipe, and the lower end of the air cylinder is communicated with the interior of the outer heat insulation layer; valve rod and butterfly valve are in the section of admitting air, and the butterfly valve is fixed on the valve rod, and valve rod one end is passed section lateral part of admitting air and cylinder lateral part and is got into in the cylinder, and valve rod one end is passed through the crank and is connected with the piston rod middle part, when the piston rod reciprocated in the cylinder, can drive the valve rod through the crank and rotate, and then make the butterfly valve rotate and seal or open the section of admitting air.
Further, the mixed gas filled in the capsule body is formed by mixing argon and helium. Because argon is an inert gas, the heat conducting performance is lower, the chemical structure is more stable, and in addition, helium and argon belong to the same inert gas, the chemical structure is stable, and the mutual reaction cannot be realized.
Furthermore, the inner heat-insulating layer is an interlayer between the inner shell and the outer heat-insulating layer, metal foils are respectively adhered to the outer surface of the inner shell and the inner wall of the outer heat-insulating layer, glass fiber cloth with low heat conductivity coefficient is filled in the interlayer, and the interlayer is vacuumized to keep the vacuum degree of the interlayer at 1.333 multiplied by 10-1To 1.333X 10-6Pa. Wherein the metal foil can reduce outside coefficient of thermal radiation, and low coefficient of thermal conductivity's glass fiber cloth and vacuum environment also can reduce heat conduction efficiency simultaneously to effectively reduce the inside and external heat exchange of inner shell, and then guarantee that the liquid nitrogen in the inner shell is putting out a fire land mine annThe gasification amount of the coal is reduced in the process of storage in the goaf.
Further, the shape of the inner shell is spherical. The shape ensures that the fire extinguishing mine is dispersed in stress and is not easy to damage when being hit by gangue.
An arrangement method for suppressing heating and oxidizing of coal in a goaf to extinguish fire is disclosed, which comprises the following steps:
step one, determining the opening temperature of a valve
Collecting coal samples on the site of a goaf where a fire extinguishing mine is required to be laid, and measuring the coal spontaneous combustion critical temperature T of the coal samples by carrying out a programmed heating experiment on the collected coal samples1And determining the temperature as a valve opening temperature; in the initial state, the butterfly valve seals the air inlet section due to the initial force of the pressure regulating spring on the piston rod;
step two, determining the concentration of each gas in the mixed gas of the external heat-insulating layer, comprising the following steps:
A. setting the starting pressure of the pneumatic switch to be P1Under the condition of equal volume, when the temperature of the mixed gas in the external heat-insulating layer reaches T1When the gas mixture generates thrust on the piston, the thrust is equal to or more than the starting pressure P of the pneumatic switch1；
B. Setting the initial temperature of the mixed gas of the external heat-insulating layer as T0Initial pressure of P0The amount of the substance of argon is nAThe amount of helium is nBThe volume expansion coefficient of argon is alpha, the volume expansion coefficient of helium is beta, and the initial volume of the mixed gas is V0Then according to the formula PV ═ nRT, where R is the ideal gas constant, the volume of the gas mixture after expansion is obtained
Simultaneous V1＝VmnA(1+αΔT)+VmnB(1+ β Δ T) and P1V1＝(nA+nB) RT gives nAAnd nBA value of (b), wherein VmIs the molar volume of the gas, and DeltaT is the coal spontaneous combustion critical temperature T1Initial temperature T with outer insulation layer0Difference of (2)Further, the concentration of argon and helium in the mixed gas in the outer heat-insulating layer can be obtained;
step three, burying the fire-extinguishing mine, comprising the following steps:
firstly, the volume of liquid nitrogen contained in the fire extinguishing mine is set as V0The densities of liquid nitrogen and nitrogen are respectively rho0、ρ1According to
Obtaining the mass m of the liquid nitrogen, and
obtaining the volume V of the fire-extinguishing mine after filling liquid nitrogen and gasifying1(ii) a Knowing that the coal void ratio of the goaf is n, the action range of the fire extinguishing mine in the goaf is obtained
Then V is put in2Bringing in
Obtaining the influence radius r of the gasified liquid nitrogen in the fire extinguishing mine in the goaf; then according to the set liquid nitrogen volume V0Liquid nitrogen is injected into the fire extinguishing mines through the nitrogen injection holes of the fire extinguishing mines to complete the preparation work of the fire extinguishing mines;
setting the distance between each fire extinguishing mine in the goaf according to the obtained influence radius of the fire extinguishing mines, wherein the arrangement distance l between two adjacent fire extinguishing mines is less than or equal to 2r, and the arrangement distance l between the fire extinguishing mines is smaller than or equal to 2 r;
thirdly, in order to avoid the impact and the damage of rocks collapsed by the roof plate of the goaf to the fire extinguishing mine, the working face is selectedAfter the periodic pressure comes, the caving rock mass is buried in a relatively stable stage, the fire extinguishing mines are buried in the goaf through the gaps between the frames during the moving and driving of the goaf, the fire extinguishing mines gradually enter the deep part of the goaf along with the continuous movement of the working face, when the temperature of the peripheral area of a certain fire extinguishing mine is increased by oxidizing residual coal, the heat is transferred to the outer heat-insulating layer, the mixed gas in the outer heat-insulating layer is heated and expanded to increase the internal pressure, and when the temperature is increased to the set temperature T1At the moment, the pressure exerted by the mixed gas on the piston and the piston rod in the cylinder is larger than the starting pressure P1The piston rod begins at the inside rebound of cylinder, at the piston rod removal in-process, drive the valve rod through the crank and rotate, and then make the butterfly valve rotate and make it open, liquid nitrogen in the inner shell gasifies rapidly this moment, and through the section of admitting air from two exhaust sections to regional release a large amount of low temperature nitrogen gas on every side, and then cool down rapidly to this high temperature coal body around the land mine of putting out a fire, the oxygen gas around the land mine of putting out a fire of nitrogen gas replacement forms the anaerobic environment of a period simultaneously, effectively prevent that the further oxidation of left coal heaies up, realize the goaf effect of putting out a fire.
Compared with the prior art, the invention has the following advantages:
1. the invention adopts a double-layer heat preservation structure in the aspect of structure, the mixed gas filled in the outer heat preservation layer strengthens the heat insulation effect of the inner heat preservation layer, the liquid nitrogen in the inner shell of the device is ensured to be reduced by the influence of the ambient temperature in the transportation and installation process or after being buried in a goaf, and the gasification degree is not reached to the set temperature, meanwhile, the mixed gas in the outer heat preservation layer can be used as the driving force of a pneumatic switch, the mixed gas in the outer heat preservation layer is influenced by the ambient high-temperature coal after being buried in the goaf, the piston and the piston rod in the cylinder are extruded by the expansion of the mixed gas in the outer heat preservation layer under the heat, so that the crank drives the valve rod to rotate and further open the butterfly valve, the low-temperature nitrogen gasified by the liquid nitrogen in the inner shell is sprayed out from the two exhaust sections of the three-way pipe, thereby effectively inhibiting the oxidation and temperature rise of the residual coal, and more timely preventing and controlling the spontaneous combustion of the goaf;
2. the invention has high utilization rate, the pressure regulating spring in the pneumatic switch can reversely act on the piston and the piston rod when the pressure of the mixed gas in the external heat-insulating layer is reduced and drive the butterfly valve in the three-way pipe to reset and close, so that the subsequent collectable fire extinguishing mines can fill liquid nitrogen into the three-way pipe again, thereby realizing multiple recycling;
3. according to the invention, when the temperature reaches the set opening temperature, liquid nitrogen in the fire extinguishing mine is gasified, a large amount of cold energy is released to the surrounding environment, the high-temperature coal body around the fire extinguishing mine is rapidly cooled, and meanwhile, the surrounding oxygen can be replaced by low-temperature nitrogen, so that an anaerobic environment is created around the fire extinguishing mine for a period of time, and the process of oxidation heating of coal is further blocked, because 1m of the environment is 1m3Can expand to 696m3The pure gaseous nitrogen can finally completely cover the whole goaf, and the fire prevention and extinguishing effects of all positions of the goaf are ensured.
Drawings
FIG. 1 is a schematic view of the construction of the fire extinguishing mine of the present invention
FIG. 2 is a schematic view of the pneumatic switch of the present invention
FIG. 3 is a schematic view of the arrangement of the fire extinguishing mines in the invention
In the figure: 1. the fire extinguishing mine comprises a fire extinguishing mine body, 2, an inner shell, 3, an inner heat insulation layer, 4, an outer heat insulation layer, 5, a three-way pipe, 6, a pneumatic switch, 7, a valve rod, 8, a butterfly valve, 9, a nitrogen injection hole, 10, a piston, 11, a piston rod, 12, a pressure regulating spring, 13, a crank, 14, a cylinder, 15, an air inlet lane, 16 and an air return lane.
Detailed Description
The present invention will be further described below.
As shown in figure 1, the fire extinguishing mine for inhibiting heating and oxidation of coal in a goaf comprises an inner shell 2, an inner heat-insulating layer 3, an outer heat-insulating layer 4, a three-way pipe 5, a pneumatic switch 6, a valve rod 7 and a butterfly valve 8;
the inner heat-insulating layer 3 is wrapped outside the inner shell 2, the outer heat-insulating layer 4 is wrapped outside the inner heat-insulating layer 4, the outer heat-insulating layer 4 is a bag body, a certain amount of mixed gas is filled in the bag body, the three-way pipe 5 is positioned above the inner shell 2, the three-way pipe 5 consists of an air inlet section and two exhaust sections, and the air inlet section of the three-way pipe 5 is communicated with the inner cavity of the inner shell 2; a nitrogen injection hole 9 is formed in the inner shell 2, the nitrogen injection hole 9 penetrates through the inner heat-insulating layer 3 and the outer heat-insulating layer 4, so that the inner cavity of the inner shell 2 is communicated with the outside, liquid nitrogen is injected into the inner cavity of the inner shell 2 through the nitrogen injection hole 9, and the nitrogen injection hole 9 is sealed through a sealing plug;
as shown in fig. 2, the pneumatic switch 6 includes two air cylinders 14, two pistons 10, a piston rod 11, two pressure regulating springs 12 and a crank 13, the two pistons 10 are respectively fixed at two ends of the piston rod 11, the piston rod 11 is located inside the air cylinder 14, the two pistons 10 are in sliding seal with the inner wall of the air cylinder 14, the pressure regulating springs 12 are located inside the air cylinder 14, one end of each pressure regulating spring is fixedly connected with the upper end of the air cylinder 14 through a spring fixing seat, the other end of each pressure regulating spring 12 is connected with one piston 10 of the piston rod 11, the air cylinder 14 is vertically fixed at one side of an air inlet section of the three-way pipe 5, and the lower end of the air cylinder 14 is communicated with the inside of the outer heat insulation layer 4; valve rod 7 and butterfly valve 8 are in the section of admitting air, and butterfly valve 8 fixes on valve rod 7, and 7 one end of valve rod passes in section lateral part of admitting air and 14 lateral parts of cylinder get into cylinder 14, and 7 one end of valve rod is connected with 11 middle parts of piston rod through crank 13, when piston rod 11 reciprocated in cylinder 14, can drive valve rod 7 through crank 13 and rotate, and then made butterfly valve 8 rotate and seal or open the section of admitting air.
Further, the mixed gas filled in the capsule body is formed by mixing argon and helium. Because argon is an inert gas, the argon gas has lower heat-conducting property and a more stable chemical structure, and helium has the characteristic of good heat-conducting property, belongs to the inert gas with argon gas, has a stable chemical structure and cannot react with each other.
Further, the inner insulating layer 3 is an interlayer between the inner shell 2 and the outer insulating layer 4, metal foils are adhered to the outer surface of the inner shell 2 and the inner wall of the outer insulating layer 4 (namely two side walls of the interlayer), glass fiber cloth with low heat conductivity coefficient is filled in the interlayer, and the interlayer is vacuumized to keep the vacuum degree of the interlayer at 1.333 x 10-1To 1.333X 10-6Pa. Wherein the metal foil can reduce outside thermal radiation coefficient, and low coefficient of thermal conductivity's glass fiber cloth and vacuum environment also can reduce heat conduction efficiency simultaneously to effectively reduce the inside and external heat exchange of inner shell, and then guarantee that the liquid nitrogen in the inner shell 2 reduces its gasification volume in installation of the land mine 1 of putting out a fire and follow-up storage in the collecting space area in-process.
Further, the shape of the inner case 2 is spherical. The shape ensures that the fire extinguishing mine 1 is dispersed in stress when being hit by gangue and is not easy to damage.
As shown in fig. 3, the fire extinguishing mine 1 of the present invention is applied to the coal spontaneous combustion prevention project of a certain mine 1708 working face for inhibiting the heating and oxidation of coal in a goaf, and the specific arrangement method is as follows:
step one, determining the opening temperature of a valve
Collecting coal samples on the site of a goaf where the fire extinguishing mine 1 needs to be laid, and measuring the coal spontaneous combustion critical temperature T of the coal samples by carrying out a programmed heating experiment on the collected coal samples1At 70 ℃ and this temperature was determined as the valve opening temperature; in the initial state, the butterfly valve 8 seals the air inlet section due to the initial force of the pressure regulating spring 12 on the piston rod 11;
step two, determining the concentration of each gas in the mixed gas of the external heat-insulating layer, comprising the following steps:
A. the volume of the external heat-insulating layer 4 is determined to be 2L, the environmental pressure of the working surface is 0.101MPa, the relative pressure of the pneumatic switch 6 for opening the valve is 0.3MPa, and the absolute pressure for opening the valve is P10.401MPa (the value changes with the environmental pressure), the initial temperature of the mixed gas filled in the external heat-insulating layer 4 is 25 ℃, the initial pressure is 0.2MPa, and the volume expansion coefficient of the argon in the mixed gas is 2.4760 multiplied by 10-3The volume expansion coefficient of helium is 4.0360X 10-2Let the amount of the substance of argon be nAThe amount of helium is nBAccording to the formula
Simultaneous V1＝VmNA(1+αΔT)+VmnB(1+ β AT) and P1V1＝(nA+nB) RT gives nAAnd nBThe concentration of argon and helium in the mixed gas in the outer heat-insulating layer can be respectively 75% and 25%;
step three, burying the fire extinguishing mine, comprising the following steps:
filling 1L of liquid nitrogen into an inner shell 2 of each fire extinguishing mine, wherein the average porosity of the goaf is 0.3, and the influence radius of the gasified liquid nitrogen in the fire extinguishing mine in the goaf is about 10m according to a formula; completing the preparation work of the fire extinguishing mine 1;
setting the distance between each fire extinguishing mine 1 in the goaf according to the obtained fire extinguishing mine influence radius by combining the difference of coal spontaneous combustion danger degrees of the goaf air inlet lane 15 side and the air return lane 16 side, wherein the arrangement distance between two adjacent fire extinguishing mines 1 is 20m, and because coal spontaneous combustion three zones of the goaf continuously move along with the propulsion of a working face and air leakage easily occurs at the goaf air return lane 16 side in the actual mining process, the arrangement distance of the fire extinguishing mines 1 at the goaf air return lane 16 side is smaller than that at the goaf air inlet lane 15 side, the interval between the fire extinguishing mines 1 is gradually increased along with the distance from the air return lane, and the fire extinguishing mines 1 at the air inlet lane 15 side are buried more deeply into the goaf;
thirdly, for avoiding the impact and the destruction of the rocks collapsed by the roof plate of the goaf on the fire extinguishing mine 1, the period of the working face is chosen to be pressed, the stage of the collapsed rocks which is relatively stable is buried, and the fire extinguishing mine 1 is buried into the goaf through the gap between the frames during the driving period of the goaf, the fire extinguishing mine 1 gradually enters the deep part of the goaf along with the continuous transition of the working face, when the oxidizing and the temperature rise of the residual coal appear in the peripheral area of a certain fire extinguishing mine 1, the heat is transferred to the outer heat-insulating layer 4 of the fire extinguishing mine 1, the mixed gas in the outer heat-insulating layer 4 is heated and expanded to cause the internal pressure to rise, and when the temperature rises to the set temperature T1At this time, the pressure of the mixed gas applied to the piston 10 and the piston rod 11 in the cylinder 14 is larger than the starting pressure P10.401MPa, piston rod 11 begins at the inside rebound of cylinder 14, at piston rod 11 removal in-process, drive valve rod 7 through crank 13 and rotate, and then make butterfly valve 8 rotate and make it open, the liquid nitrogen in inner shell 2 gasifies rapidly this moment, and through the section of admitting air from two exhaust sections to regional release a large amount of low temperature nitrogen gas on every side, and then carry out rapid cooling to this high temperature coal body around the mine of putting out a fire 1, the oxygen around the mine of putting out a fire of nitrogen gas replacement forms the anaerobic environment of a period of time simultaneously, effectively prevent that the coal that remains further oxidation heaies up, realize the goaf effect of preventing and putting out a fire.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (5)
1. A fire extinguishing mine for inhibiting heating and oxidation of coal in a goaf is characterized by comprising an inner shell, an inner heat-insulating layer, an outer heat-insulating layer, a three-way pipe, a pneumatic switch, a valve rod and a butterfly valve;
the inner heat-insulating layer is wrapped outside the inner shell, the outer heat-insulating layer is wrapped outside the inner heat-insulating layer and is a bag body, a certain amount of mixed gas is filled in the bag body, the three-way pipe is positioned above the inner shell and consists of an air inlet section and two air exhaust sections, and the air inlet section of the three-way pipe is communicated with the inner cavity of the inner shell; the inner shell is provided with a nitrogen injection hole which penetrates through the inner heat-insulating layer and the outer heat-insulating layer to enable the inner cavity of the inner shell to be communicated with the outside, liquid nitrogen is injected into the inner cavity of the inner shell through the nitrogen injection hole, and the nitrogen injection hole is sealed through a sealing plug;
the pneumatic switch comprises a cylinder, two pistons, a piston rod, a pressure regulating spring and a crank, wherein the two pistons are respectively fixed at two ends of the piston rod, the piston rod is positioned in the cylinder, the two pistons are in sliding seal with the inner wall of the cylinder, the pressure regulating spring is positioned in the cylinder, one end of the pressure regulating spring is fixedly connected with the upper end of the cylinder through a spring fixing seat, the other end of the pressure regulating spring is connected with one piston of the piston rod, the cylinder is vertically fixed at one side of an air inlet section of the three-way pipe, and the lower end of the cylinder is communicated with the interior of the external heat insulation layer; valve rod and butterfly valve are in the section of admitting air, and the butterfly valve is fixed on the valve rod, and valve rod one end is passed section lateral part of admitting air and cylinder lateral part and is got into in the cylinder, and valve rod one end is passed through the crank and is connected with the piston rod middle part, when the piston rod reciprocated in the cylinder, can drive the valve rod through the crank and rotate, and then make the butterfly valve rotate and seal or open the section of admitting air.
2. The fire extinguishing mine for inhibiting heating up and oxidation of coal in a goaf according to claim 1, wherein the mixed gas filled in the capsule is formed by mixing argon and helium.
3. The fire extinguishing mine for inhibiting heating up and oxidation of coal in goaf according to claim 1, wherein the inner insulation layer is an interlayer between the inner shell and the outer insulation layer, metal foils are adhered to both the outer surface of the inner shell and the inner wall of the outer insulation layer, glass fiber cloth with low thermal conductivity coefficient is filled in the interlayer, and the interlayer is vacuumized to keep the vacuum degree at 1.333 x 10-1To 1.333X 10-6Pa。
4. The fire fighting mine of claim 1, wherein the inner shell is spherical in shape.
5. The arrangement method for inhibiting the heating up and oxidizing of the coal in the goaf to extinguish the fire according to any one of claims 1 to 4, which is characterized by comprising the following specific steps:
step one, determining the opening temperature of a valve
Collecting coal samples on the site of a goaf where a fire extinguishing mine is required to be laid, and measuring the coal spontaneous combustion critical temperature T of the coal samples by carrying out a programmed heating experiment on the collected coal samples1And determining the temperature as a valve opening temperature; in the initial state, the butterfly valve seals the air inlet section due to the initial force of the pressure regulating spring on the piston rod;
step two, determining the concentration of each gas in the mixed gas of the external heat-insulating layer, comprising the following steps:
A. setting the starting pressure of the pneumatic switch to be P1Under the condition of equal volume, when the temperature of the mixed gas in the external heat-insulating layer reaches T1When the gas mixture generates thrust on the piston, the thrust is equal to or more than the starting pressure P of the pneumatic switch1；
B. Setting the initial temperature of the mixed gas of the external heat-insulating layer as T0Initial pressure of P0The amount of the substance of argon is nAThe amount of helium is nBVolume of argon gasThe expansion coefficient is alpha, the volume expansion coefficient of helium is beta, and the initial volume of the mixed gas is V0Then according to the formula PV ═ nRT, where R is the ideal gas constant, the volume of the gas mixture after expansion is obtained
Simultaneous V1＝VmnA(1+αΔT)+VmnB(1+ β Δ T) and P1V1＝(nA+nB) RT gives nAAnd nBA value of (b), wherein VmIs the molar volume of the gas, and DeltaT is the coal spontaneous combustion critical temperature T1Initial temperature T with outer insulation layer0The concentration of argon and helium in the mixed gas in the outer heat-insulating layer can be further obtained;
step three, burying the fire extinguishing mine, comprising the following steps:
firstly, the volume of liquid nitrogen contained in the fire extinguishing mine is set as V0The densities of liquid nitrogen and nitrogen are respectively rho0、ρ1According to
Obtaining the mass m of the liquid nitrogen, and
obtaining the volume V of the fire-extinguishing mine after the liquid nitrogen is gasified1(ii) a Knowing that the coal void ratio of the goaf is n, the action range of the fire extinguishing mine in the goaf is obtained
Then V is put in2Bringing in
Obtaining the influence radius r of the gasified liquid nitrogen in the fire extinguishing mine in the goaf; then according to the set liquid nitrogen volume V0Liquid nitrogen is injected into the fire extinguishing mines through the nitrogen injection holes of the fire extinguishing mines to complete the preparation work of the fire extinguishing mines;
setting the distance between each fire extinguishing mine in the goaf according to the obtained influence radius of the fire extinguishing mines, wherein the arrangement distance l between two adjacent fire extinguishing mines is less than or equal to 2r, and the arrangement distance l between the fire extinguishing mines is less than or equal to 2 r;
thirdly, in order to avoid impact and damage of rocks collapsed due to the fact that a top plate of the goaf bears pressure on the fire extinguishing mine, after periodic pressure of a working face is exerted, the collapsed rocks are buried in a relatively stable stage, the fire extinguishing mine is buried in the goaf through gaps between frames during moving and driving of the goaf, the fire extinguishing mine gradually enters deep parts of the goaf along with continuous pushing of the working face, when the temperature of coal left in the peripheral area of a certain fire extinguishing mine is increased through oxidation and heating, heat is transferred to an outer heat insulation layer, mixed gas in the outer heat insulation layer is heated and expanded to enable the internal pressure intensity of the mixed gas to be increased, and when the temperature is increased to the set temperature T1At the moment, the pressure exerted by the mixed gas on the piston and the piston rod in the cylinder is larger than the starting pressure P1The piston rod begins at the inside rebound of cylinder, at the piston rod removal in-process, drive the valve rod through the crank and rotate, and then make the butterfly valve rotate and make it open, liquid nitrogen in the inner shell gasifies rapidly this moment, and through the section of admitting air from two exhaust sections to regional release a large amount of low temperature nitrogen gas on every side, and then cool down rapidly to this high temperature coal body around the land mine of putting out a fire, the oxygen gas around the land mine of putting out a fire of nitrogen gas replacement forms the anaerobic environment of a period simultaneously, effectively prevent that the further oxidation of left coal heaies up, realize the goaf effect of putting out a fire.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116878310A (en) * | 2023-07-20 | 2023-10-13 | 中国矿业大学(北京) | Circulation water type coal storage pile oxidation heat energy utilization and spontaneous combustion control system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116878310A (en) * | 2023-07-20 | 2023-10-13 | 中国矿业大学(北京) | Circulation water type coal storage pile oxidation heat energy utilization and spontaneous combustion control system |
| CN116878310B (en) * | 2023-07-20 | 2023-12-08 | 中国矿业大学(北京) | Circulation water type coal storage pile oxidation heat energy utilization and spontaneous combustion control system |
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