WO2021253593A1 - Downhole liquid co2 phase transition-powered multi-functional filling system and usage method - Google Patents

Abstract

A downhole liquid CO₂ phase transition-powered multi-functional filling system, which belongs to the technical field of fire preventing and extinguishing for a coal mine. Said filling system comprises a power system, an injection system for filling a fire preventing and extinguishing material into a goaf, and a foam system, and the power system comprises a liquid CO₂ storage and transport tank (1) and a main pipeline connected thereto; the liquid CO₂ enters a material storage tank (3) through a first branch pipeline after being vaporized under the action of a vaporizer (8), and the pressurized material storage tank (3) has sufficient power and fills the fire preventing and extinguishing material into the goaf through a third pipeline; and when a foam gel-type fire preventing and extinguishing material needs to be filled, the pressurized material storage tank (3) is connected to a fourth pipeline, and then is combined with the foam system connected to a second branch pipeline, so that the foam gel-type fire preventing and extinguishing material is filled into the goaf by means of foams generated by a foam maker. Also disclosed is a method for using the downhole liquid CO₂ phase transition-powered multi-functional filling system. The filling system does not require a power device, allows for filling of different fire preventing and extinguishing materials, and has widespread applicability.

Description

Underground liquid CO2 phase change power multifunctional perfusion system and use method Technical field

The invention relates to the technical field of coal mine fire prevention and extinguishing, in particular to a multifunctional perfusion system capable of perfusing different fire extinguishing materials and a use method thereof.

Background technique

Fires caused by spontaneous combustion of coal have caused huge economic losses, casualties, and environmental pollution. At present, fire-fighting technologies such as grouting, inert gas injection, and gel injection have effectively inhibited the spontaneous combustion of coal, but the power for injecting these fire-fighting materials comes from pneumatic grouting pumps, screw pumps, and air compressors. For example, 201810247360.X discloses a grouting tank for fire extinguishing and grouting in coal mines, including a main chamber, agitator, filter chamber and a starting motor. The main chamber is connected to the filter chamber, and the connection is provided with a filter. The upper part of the side is provided with a water filling port, and the lower right part of the main chamber is connected with the slurry storage tank. A power engine is arranged in the slurry storage tank, and a slurry pipeline is provided on the power engine. It mainly uses the power engine as the power source. However, these power devices have problems such as complicated operation process, high noise, and high maintenance cost. In addition, the infusion system of inert gas (such as CO ₂ , N ₂ ) fire-fighting technology is mostly set on the ground, and the deep mine transportation pipeline is long, which is prone to technical problems such as pressure loss, gas leakage, pipeline blockage, etc., reducing its fire-fighting efficient.

Existing fire-fighting equipment can only infuse a single kind of fire-fighting material, for example, foam gel cannot be infused while injecting inert gas. Based on this, the research on a multifunctional infusion system that does not rely on conventional power devices, but can also inject different fire extinguishing materials into the goaf area has become a major technical problem that needs to be solved by those skilled in the art.

Technical solutions

One of the objectives of the present invention is to provide a downhole liquid CO ₂ phase change power multifunctional injection system, which does not rely on conventional power devices. It uses the liquid CO ₂ phase change pressure as the power source, and the liquid CO ₂ enters the material storage after vaporization. Tanks, pressurized material storage tanks have sufficient power, continuous and stable high-pressure infusion is conducive to the uniform distribution of fire-fighting materials in the goaf, and can effectively cover high fire sources in the goaf. According to the needs of on-site fire-fighting work, the perfusion system of the present invention can spray anti-extinguishing materials such as inhibitors, water injection, and three-phase foam injection into the goaf.

In order to achieve the above objectives, the technical problems that the present invention needs to overcome are:

How to continuously and stably pour fire-fighting materials into the goaf without relying on conventional power plants;

How to inject a variety of fire-fighting materials into the goaf.

In order to solve the above technical problems, the present invention adopts the following technical solutions:

An underground liquid CO ₂ phase change power multifunctional infusion system, which includes a power system and a grouting system and a foam system for injecting fire-fighting materials into the goaf. The power system includes a liquid CO ₂ storage and transportation tank and transportation and liquid CO main duct connecting the tank _2, the main pipe is provided with a respective evaporator, temperature control and monitoring unit, a vaporizer for liquid CO ₂ storage and transportation of liquid CO ₂ in tank Carry out vaporization, and carry out real-time monitoring and control _{of the CO 2} temperature in the main pipeline through the temperature control and monitoring unit;

The other end of the main pipeline is connected to two branch pipelines, which are the first branch pipeline and the second branch pipeline respectively;

The grouting system includes a material storage tank, related valves, atomizing nozzles, and the first branch pipeline, and the material storage tank, related valves, and atomizing nozzles are all located in the first branch pipeline superior;

The foam system includes a foamer, a related control valve and a second branch pipeline, and the foamer and the relevant control valve are all located on the second branch pipeline;

At the end of the material storage tank are connected two pipelines, a third pipeline and a fourth pipeline, the third pipeline leads to the goaf, and the fourth pipeline is connected to the generator Bubbler

After the liquid CO ₂ is vaporized under the action of the vaporizer, it enters the material storage tank through the first branch pipeline, and the pressurized material storage tank has sufficient power and passes through the third The pipeline is filled with fire-fighting materials into the goaf; when it is necessary to fill foam-gel fire-extinguishing materials, the pressurized material storage tank is connected to the fourth pipeline, and then combined with the second branch pipeline. Foam system, inject foam gel fire-extinguishing materials into the goaf through a foamer.

The beneficial technical effects directly brought about by the above technical solutions are:

The above-mentioned main technical concept "using the liquid CO ₂ phase change pressure as the power source" can avoid the use of conventional power devices, and further avoid some of the disadvantages of conventional devices in the prior art due to complex operation, high noise, and high maintenance costs. Specifically, in the present invention, the liquid CO ₂ storage tank enters the material storage tank after being vaporized by the vaporizer, and the pressurized material storage tank has sufficient power, that is, the material storage tank obtains the pressure of the _{liquid CO 2 phase change} This sufficient power source, therefore, the continuous and stable high-pressure material storage tank is conducive to pouring fire-fighting materials into the goaf, and makes the fire-fighting materials evenly distributed, thereby effectively covering the high fire sources in the goaf.

The above technical solution includes a grouting system and a foam system. Through the adjustment of related valves, the grouting system can be used to inject fire-preventing materials such as slurry and water into the goaf according to actual needs. The foam system can also be used for mining. Three-phase foam, foam gel and other fire-fighting materials are poured into the empty area. Therefore, the infusion system of the present invention is multifunctional. It can not only inject a single fire-extinguishing material, but also inject a variety of fire-extinguishing materials into the goaf.

As a preferred solution of the present invention, the liquid CO ₂ storage tank is filled with liquid CO ₂ by a liquid CO ₂ tanker on the well, and the filled liquid CO ₂ storage tank is transported to the well. The temperature The control unit is a temperature controller, the temperature monitoring unit is a temperature detector, and the vaporizer, temperature controller, and temperature detector are respectively arranged on the main pipeline from front to back; in the liquid CO ₂ storage The main pipeline between the tank and the vaporizer is also provided with a liquid inlet and outlet valve.

In the above technical scheme, the _{liquid CO 2} storage and transportation tanks are filled with liquid CO _{2 through the liquid CO 2} tanker on the well, which avoids the pressure loss caused by the long-distance transportation of the ground direct injection CO ₂ fire-fighting system, and the problems of icing and pipe blockage are avoided. . Particularly, when the fire-extinguishing material is _{poured, CO 2 is} injected into the goaf along with the pipeline to give play to the excellent suffocation, cooling and inerting characteristics of the inert gas.

As another preferred solution of the present invention, the relevant valves in the grouting system include a first flow control valve, a first stabilizing valve, a first one-way valve, a first pressure gauge, a first shutoff valve, and a first Two shut-off valves, a first pressure relief valve, and a second pressure relief valve, wherein the first flow control valve, the first stabilizing valve, and the first one-way valve are respectively arranged in the first branch from front to back. On the road pipeline, a first metal hose is provided on the first branch pipeline between the first pressure regulator valve and the first one-way valve, and the material storage tank is provided on the first branch pipeline. Behind the valve, the first pressure gauge is connected above the material storage tank, the first shutoff valve and the second pressure relief valve are sequentially connected to the third pipeline, and the first The second shutoff valve and the first pressure relief valve are sequentially connected to the fourth pipeline.

In the above technical solution, _{the flow and pressure of CO 2} in the grouting system are monitored and adjusted through the relevant valves. The purpose is to maintain sufficient power in the material storage tank. The specific monitoring and adjustment methods are described in the specific implementation examples. Will explain in further detail.

Further, the materials in the above-mentioned material storage tank include coagulant, inhibitor, water, foaming agent, bentonite or a mixture thereof.

In the above technical solution, the material in the material storage tank may include, in addition to the above fire-fighting materials, fire-fighting materials not limited by the present invention.

Further, the relevant control valve in the aforementioned foam system includes a third shutoff valve, a second flow control valve, a second pressure regulator valve, a second pressure gauge, and a second check valve, which are sequentially arranged on the second branch pipeline. The aforementioned foamer is located behind the aforementioned second one-way valve, and a second metal hose is provided on the second branch pipe between the aforementioned second regulator valve and the second pressure gauge.

Further, the above foamer includes a foamer main body, a slurry inlet, a carbon dioxide gas inlet, and a fire-extinguishing material outlet are provided on the foamer main body, and a carbon dioxide gas introduction gap is provided in the foamer main body. , Venturi tube, current collector, foam net.

Further, the aforementioned foamed mesh includes a stainless steel cross fixing frame, stainless steel bolts, a stainless steel disc, and a stainless steel mesh. The aforementioned stainless steel bolts are fixed in the middle of the aforementioned stainless steel cross fixing frame, and the ends of the aforementioned stainless steel fixing frame are just clamped. On the inner wall of the above-mentioned stainless steel disc.

Further, the aforementioned first pressure relief valve and second pressure relief valve discharge gas or liquid in the pipeline when the pressure in the pipeline is higher than 2.4-3.4MPa; the aforementioned first pressure regulator valve and second pressure regulator valve Allow gas or liquid with pressure higher than 1.5-2MPa in the pipeline to pass through.

Further, the above-mentioned atomization nozzle is a detachable design. The atomizing nozzle is set as a detachable type. According to the different fire-fighting materials in the material storage tank, matching nozzles are used to inject different fire-fighting materials into the goaf.

Another object of the present invention is to provide a _{method for using the above-mentioned downhole liquid CO 2} phase change power multifunctional injection system, which sequentially includes the following steps:

a. Connect the multifunctional perfusion system one by one, and check the air tightness;

b. Pouring fire-fighting materials into the goaf through the grouting system:

Connect the third pipeline connected to the goaf and close the fourth pipeline, open the main liquid _{inlet and outlet valves connected to the liquid CO 2} storage tank, adjust the vaporizer to observe the temperature monitoring unit, and open the temperature control unit to keep the temperature appropriate;

Adjust the relevant valves of the grouting system, observe the proper value of the pressure gauge on the material storage tank, install the atomizing nozzle to spray the inhibitor, and disassemble the atomizing nozzle to inject water and yellow mud;

c. Pouring foam gel fire-fighting materials into the goaf through the foam system:

Close the third pipeline, connect the fourth pipeline, open the main liquid _{inlet and outlet valves connected to the liquid CO 2} storage and transportation tank, adjust the vaporizer to observe the temperature monitoring unit, and open the temperature control unit to keep the temperature appropriate;

Adjust the relevant control valves of the foam system. After the value of the pressure gauge on the material storage tank continues to stabilize, use the foamer to infuse the hindered foam, three-phase foam or foam gel.

Beneficial effect

Compared with the prior art, the present invention brings the following beneficial technical effects:

(1) The multifunctional perfusion system of the present invention can be equipped with a variety of fire-fighting materials, and the material storage tank can be filled with coagulant, inhibitor, water, foaming agent, bentonite, etc. The foam system plays a role when injecting fire-fighting materials such as foam gel, barrier foam and three-phase foam; the grouting system plays a role when grouting, spraying inhibitors, and water injection.

(2) The multifunctional perfusion system of the present invention is _{a power system with a liquid CO 2} storage and transportation tank as the main body. This part can not only provide sufficient power, but also can exert the excellent cooling, suffocation and explosion suppression functions of the inert gas. The liquid CO ₂ The storage and transportation tanks can be repeatedly poured on the ground, and the storage and transportation tanks can be used in turn to provide sufficient power; the fire-fighting material system with material storage tanks as the main body can be preferably sprayed with chemical inhibitors and injection Phase foam, yellow mud, foam gel and other materials can significantly improve the efficiency of coal fire prevention.

(3) In the use method of the multifunctional perfusion system of the present invention, by switching related pipes and valves, different types of fire-fighting materials can be poured into the goaf.

Description of the drawings

The present invention will be further explained below in conjunction with the accompanying drawings:

Figure 1 is a schematic diagram of the structure of the downhole liquid CO _{2 phase change power multifunctional injection system of the present invention;}

Figure 2 is a schematic diagram of the structure of the foaming device of the present invention;

Figure 3 is a schematic diagram of the structure of the foaming net in the foaming device of the present invention;

In the picture: 1-liquid CO ₂ storage and transportation tank, 2-temperature controller, 3-material storage tank, 4-foamer, 5-liquid CO ₂ tanker, 6-inlet and outlet main valve, 7-infusion valve, 8 -Vaporizer, 9- Temperature detector, 10- First flow control valve, 11- First regulator valve, 12- First metal hose, 13- First check valve, 14- First pressure gauge, 15- The second flow control valve, 16-second regulator valve, 17-second metal hose, 18-second pressure gauge, 19-second check valve, 20-first shut-off valve, 21-second shut-off valve , 22-Third shut-off valve, 23-First pressure relief valve, 24-Second pressure relief valve, 25-Atomization nozzle, 4-1-Slurry inlet, 4-2-Carbon dioxide gas introduction gap, 4-3- Venturi tube, 4-4-carbon dioxide gas inlet, 4-4-5 collector, 4-6-foam net, 4-6-1-stainless steel cross fixing frame, 4-6-2-stainless steel bolts, 4- 6-3-stainless steel disc, 4-6-4-stainless steel net, 4-7-fire-extinguishing material outlet.

Embodiments of the present invention

The present invention proposes a downhole liquid CO ₂ phase change power multifunctional injection system and a method of use. In order to make the advantages and technical solutions of the present invention clearer and clearer, the present invention will be described in detail below with reference to specific embodiments.

The present invention is an underground liquid CO ₂ phase change power multifunctional perfusion system, as shown in Fig. 1, comprising a liquid CO ₂ storage and transportation tank 1, a temperature controller 2, a material storage tank 3, a foamer 4, and a liquid CO ₂ tanker 5. Liquid inlet and outlet valve 6, filling valve 7, vaporizer 8, temperature detector 9, first flow control valve 10, first stabilizing valve 11, first metal hose 12, first one-way valve 13, first Pressure gauge 14, second flow control valve 15, second regulator valve 16, second metal hose 17, second pressure gauge 18, second check valve 19, first shutoff valve 20, second shutoff valve 21, The third shutoff valve 22, the first pressure relief valve 23, the second pressure relief valve 24, and the atomization nozzle 25.

Among them, the liquid CO ₂ storage and transportation tank 1, the temperature controller 2, the liquid inlet and outlet valve 6, the vaporizer 8, and the temperature detector 9 together constitute a power system. Among them, the liquid CO ₂ storage and transportation tank 1 is connected to the main pipeline, and the main pipeline is The main valve for inlet and outlet, the vaporizer 8, the temperature controller 2, and the temperature detector 9 are respectively provided. The liquid CO ₂ tanker 5 is located on the ground and _{fills the liquid CO 2} storage and transportation tank 1 with liquid CO ₂ , and the liquid CO ₂ storage and transportation tank 1 is filled and transported downhole to connect the vaporizer 8, the temperature controller 2 and the temperature detector 9 in turn.

The above-mentioned main pipeline branches into two branch pipelines, namely the first branch pipeline and the second branch pipeline, wherein the first branch pipeline is connected to the grouting system, and the second branch pipeline is connected to the foaming system.

Connect the first flow control valve 10, the first stabilizing valve 11, the first metal hose 12 and the first one-way valve 13 to the first branch pipeline of the grouting system, and then connect the first pressure gauge 14 The end of the material storage tank 3 is connected to the third pipeline and the fourth pipeline, and the first shutoff valve 20 and the first pressure relief valve 24 are connected to the third pipeline to lead into the goaf;

Foaming system, connect the third cut-off valve 22, the second flow control valve 15, the second stabilizing valve 16, the second metal hose 17, the second pressure gauge 18 and the second one-way valve to the second branch pipeline 19. At the end, connect to the carbon dioxide gas inlet 4-4 of the foamer.

The end of the material storage tank is connected to the slurry inlet 4-1 of the foamer through a fourth pipe.

As shown in combination with Figures 2 and 3, the foamer includes a foamer main body, on which a slurry inlet 4-1, a carbon dioxide gas inlet 4-4, and a fire-extinguishing material outlet 4-7 are provided. The main body of the foamer is provided with a carbon dioxide gas introduction gap 4-2, a venturi tube 4-3, a current collector 4-5, and a foaming net 4-6. Foam mesh 4-6 includes stainless steel cross fixing frame 4-6-1, stainless steel bolt 4-6-2, stainless steel disc 4-6-3 and stainless steel mesh 4-6-4, stainless steel bolt is fixed on stainless steel cross fixing frame In the middle, the end of the stainless steel fixing frame happens to be clamped on the inner wall of the stainless steel disc.

Preferably, the aforementioned first pressure relief valve and second pressure relief valve discharge the gas or liquid in the pipeline when the pressure in the pipeline is higher than 2.4-3.4MPa; the aforementioned first pressure regulator valve and second pressure regulator valve Allow gas or liquid with pressure higher than 1.5-2MPa in the pipeline to pass through.

Preferably, the above-mentioned atomizing nozzle is a detachable design, which is convenient for replacement.

The method of using the multifunctional perfusion system of the present invention will be described in detail below.

Specifically include the following steps:

Step one, grouting system

Connect all parts of the system and check the air tightness. Open the first shut-off valve 20, close the second shut-off valve 21 and the third shut-off valve 22, open the downhole inlet and outlet main valve 6, adjust the vaporizer 8 and observe the temperature detector 9, Turn on the temperature controller 2 to keep the temperature appropriate; adjust the first flow control valve and the first stabilizing valve, observe that the pressure gauge on the material storage tank is suitable, install the atomizing nozzle to spray the inhibitor, and disassemble the atomizing nozzle to inject water and yellow mud.

Step two, foaming system

Connect all parts of the system, close the first shut-off valve 20, open the second shut-off valve 21 and the third shut-off valve 22, open the downhole inlet and outlet main valve 6, adjust the vaporizer 8 to observe the temperature detector 9, and turn on the temperature controller 2. Keep the temperature appropriate;

Adjust the second flow control valve 15 and the second stabilizing valve 16, after the value of the pressure gauge on the material storage tank 3 continues to stabilize, the foamer 4 is used to infuse hindered foam, three-phase foam, foam gel, etc.

The present invention will be described in detail below in conjunction with specific embodiments.

Example 1:

The liquid CO ₂ storage and transportation tank 1 is connected to the liquid CO ₂ tanker 5 through the inlet and outlet main valve 6 and the filling valve 7 on the ground. The inlet and outlet main valves 6 and the filling valve 7 are opened to remove the liquid CO ₂ in the liquid CO _{2 tanker 5} Fill the liquid CO ₂ storage and transportation tank 1, and transport the liquid CO ₂ storage and transportation tank 1 to the well. Connect the inlet and outlet main valve 6, vaporizer 8, temperature controller 2, temperature detector 9, and first flow control valve 10 through pipelines. , The first regulator valve 11, the first metal hose 12, the first one-way valve 13, the material storage tank 3 containing the inhibitor, the material storage tank 3 is connected to the first shutoff valve 20 and the second pressure relief valve in sequence 24 and atomizing nozzle 25. The first step is to open the liquid inlet and _{outlet valve 6 to let the liquid CO 2} flow out, adjust the vaporizer 8 to vaporize the liquid CO ₂ , and observe the temperature detector 9 at the same time. The controller 2 adjusts the temperature to above 0°C, and in the second step, open and adjust the first flow control valve 10 and the first stabilizing valve 11 to adjust the values to the target position. After the above operations are completed, the inhibitor can be sprayed to the goaf _{, The liquid CO 2} storage and transportation tank 1 can be rotated according to the specific implementation conditions, and the temperature and pressure of each part of the system can be adjusted according to site requirements.

Example 2:

The liquid CO _{2 storage and transportation tank 1 is connected to the liquid CO 2} tanker 5 through the liquid inlet and outlet main valve 6 and the filling valve 7 on the ground. The liquid inlet and _{outlet main valve 6 and the filling valve 7 are opened to fill the liquid CO 2} into the storage and transportation tank 1. Connect the liquid CO ₂ storage tank 1 to the main inlet and outlet valve 6, the vaporizer 8, the temperature controller 2, and the temperature detector 9. After the temperature detector 9, it is divided into two branch pipelines, the first branch pipeline Connect the first flow control valve 10, the first stabilizing valve 11, the first metal hose 12, the first one-way valve 13 and the material storage tank 3 containing foaming liquid in sequence, and the material storage tank is connected to the second shutoff valve 21 The end of the second pressure relief valve 23 is connected to the foamer slurry inlet 4-1. The second branch pipeline is successively connected with the third shut-off valve 22, the second flow control valve 15, the second stabilizing valve 16, the second metal hose 17, the second pressure gauge 18, and the second one-way valve 19, and finally It is connected to the carbon dioxide gas inlet 4-4 of the foamer.

The first step is to close the first shut-off valve 20, open the second shut-off valve 21, and the third shut-off valve 22, open the liquid inlet and _{outlet valve 6 to let the liquid CO 2} flow out, and vaporize the liquid CO ₂ through the vaporizer 8 while observing the temperature detection If the temperature is lower than 0℃, in order to avoid freezing of the pipeline, immediately turn on the temperature controller 2 to keep the temperature above 0℃; in the second step, open and adjust the first flow control valve 10 and the first regulator valve 11. As well as the second flow control valve 15, the second pressure regulator valve 16, adjust the value to the desired position. After completing the above operations, observe the foam shape at the outlet of the pipeline. If the foam shape does not meet the requirements, adjust the pressure valve. Fill the goaf with foam fire-fighting materials such as barrier foam and foam gel. The liquid CO ₂ storage and transportation tank 1 can be rotated according to the specific implementation conditions. The temperature and pressure of each part of the system can be adjusted according to the field application.

The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto.

Although terms such as liquid CO ₂ storage tank, temperature controller, material storage tank, foamer, etc. are used more in this article, the possibility of using other terms is not ruled out. The use of these terms is only for more convenience Describe and explain the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

It should be further explained that the specific embodiments described in this document are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or additions to the specific embodiments described or use similar alternatives, but they will not deviate from the spirit of the present invention or exceed the definitions defined in the appended claims. Range.

Claims (10)

1. An underground liquid CO ₂ phase change power multifunctional infusion system, which includes a power system, a grouting system and a foam system for injecting fire-fighting materials into the goaf, and is characterized in:

   The power system includes a liquid CO ₂ storage and transportation tank and _{a main pipeline connected to the liquid CO 2} storage and transportation tank. A vaporizer, a temperature control and monitoring unit are respectively provided on the main pipeline, and the vaporizer is used To vaporize the liquid CO ₂ in the liquid CO ₂ storage tank, and to monitor and control the temperature _{of the CO 2} in the main pipeline in real time through the temperature control and monitoring unit;

   The other end of the main pipeline is connected to two branch pipelines, which are the first branch pipeline and the second branch pipeline respectively;

   The grouting system includes a material storage tank, related valves, atomizing nozzles, and the first branch pipeline, and the material storage tank, related valves, and atomizing nozzles are all located in the first branch pipeline superior;

   The foam system includes a foamer, a related control valve and a second branch pipeline, and the foamer and the relevant control valve are all located on the second branch pipeline;

   At the end of the material storage tank are connected two pipelines, a third pipeline and a fourth pipeline, the third pipeline leads to the goaf, and the fourth pipeline is connected to the generator Bubbler

   After the liquid CO ₂ is vaporized under the action of the vaporizer, it enters the material storage tank through the first branch pipeline, and the pressurized material storage tank has sufficient power and passes through the third The pipeline is filled with fire-fighting materials into the goaf; when it is necessary to fill foam-gel fire-extinguishing materials, the pressurized material storage tank is connected to the fourth pipeline, and then combined with the second branch pipeline. Foam system, inject foam gel fire-extinguishing materials into the goaf through a foamer.
2. The downhole liquid CO ₂ phase change power multifunctional injection system _{according to claim 1, wherein the liquid CO 2} storage and transportation tank is filled with liquid CO _{2 through a liquid CO 2 tanker on the well.} The latter liquid CO ₂ storage tank is transported downhole, the temperature control unit is a temperature controller, the temperature monitoring unit is a temperature detector, and the vaporizer, temperature controller, and temperature detector are self-determined. It is then arranged on the main pipeline; the main pipeline between the liquid CO ₂ storage and transportation tank and the vaporizer is also provided with a liquid inlet and outlet valve.
3. The downhole liquid CO ₂ phase change power multifunctional injection system according to claim 1, characterized in that: the relevant valves in the grouting system include a first flow control valve, a first stabilizing valve, and a second A one-way valve, a first pressure gauge, a first shutoff valve, a second shutoff valve, a first pressure relief valve, and a second pressure relief valve, wherein the first flow control valve, the first pressure regulator valve, and the second pressure relief valve A one-way valve is arranged on the first branch pipeline from front to back, and a first metal soft pipe is arranged on the first branch pipeline between the first regulator valve and the first one-way valve. Pipe, the material storage tank is arranged behind the first one-way valve, the first pressure gauge is connected above the material storage tank, the first shutoff valve and the second pressure relief The valve is connected to the third pipeline in sequence, and the second shutoff valve and the first pressure relief valve are connected to the fourth pipeline in sequence.
4. The underground liquid CO ₂ phase change power multifunctional injection system according to claim 3, characterized in that: the material in the material storage tank includes coagulant, inhibitor, water, foaming agent, bentonite Or a mixture thereof.
5. _{The downhole liquid CO 2} phase change power multifunctional injection system according to claim 1, wherein the relevant control valve in the foam system includes a third shutoff valve sequentially arranged on the second branch pipeline , The second flow control valve, the second pressure regulator valve, the second pressure gauge and the second one-way valve, the foamer is located behind the second one-way valve, in the second pressure regulator A second metal hose is provided on the second branch pipeline between the valve and the second pressure gauge.
6. The downhole liquid CO ₂ phase change power multifunctional infusion system according to claim 5, wherein the foamer includes a foamer main body, and a slurry inlet is provided on the foamer main body. , Carbon dioxide gas inlet and fire-extinguishing material outlet, the main body of the foamer is provided with a carbon dioxide gas introduction gap, a venturi tube, a current collector, and a foaming net.
7. _{The underground liquid CO 2} phase change power multifunctional infusion system according to claim 6, wherein the foamed mesh includes a stainless steel cross fixing frame, a stainless steel bolt, a stainless steel disc, and a stainless steel mesh. The stainless steel bolt is fixed in the middle of the stainless steel cross fixing frame, and the end of the stainless steel fixing frame is just clamped on the inner wall of the stainless steel disc.
8. The downhole liquid CO ₂ phase change power multifunctional injection system according to claim 3, characterized in that: the first pressure relief valve and the second pressure relief valve when the pressure in the pipeline is higher than 2.4-3.4 MPa The gas or liquid in the gas or liquid is discharged; the first and second regulator valves allow the gas or liquid whose pressure in the pipeline is higher than 1.5-2MPa to pass through.
9. The downhole liquid CO ₂ phase change power multifunctional injection system according to claim 1, wherein the atomization nozzle is a detachable design.
10. _{The use method of a downhole liquid CO 2} phase change power multifunctional injection system according to any one of claims 1-9, characterized in that it comprises the following steps in sequence:

    a. Connect the multifunctional perfusion system one by one, and check the air tightness;

    b. Pouring fire-fighting materials into the goaf through the grouting system:

    Connect the third pipeline connected to the goaf and close the fourth pipeline, open the main liquid _{inlet and outlet valves connected to the liquid CO 2} storage tank, adjust the vaporizer to observe the temperature monitoring unit, and open the temperature control unit to keep the temperature appropriate;

    Adjust the relevant valves of the grouting system, observe the proper value of the pressure gauge on the material storage tank, install the atomizing nozzle to spray the inhibitor, and disassemble the atomizing nozzle to inject water and yellow mud;

    c. Pouring foam gel fire-fighting materials into the goaf through the foam system:

    Close the third pipeline, connect the fourth pipeline, open the main liquid _{inlet and outlet valves connected to the liquid CO 2} storage and transportation tank, adjust the vaporizer to observe the temperature monitoring unit, and open the temperature control unit to keep the temperature appropriate;

    Adjust the relevant control valves of the foam system. After the value of the pressure gauge on the material storage tank continues to stabilize, use the foamer to infuse the hindered foam, three-phase foam or foam gel.