A goaf connectivity detection system and a detection method

Abstract

The application provides a goaf connectivity detection system and a detection method. The detection system comprises a gas injection part configured to inject tracer gas into a goaf through a first borehole in the goaf, the gas injection part comprising: an ammonia storage device for storing ammonia gas as the tracer gas; and a gas collection part configured to collect gas in the goaf through a second borehole in the goaf and detect whether the tracer gas exists, the gas collection part comprising: an ammonia gas detection device for detecting whether ammonia gas exists in the collected gas. The goaf connectivity detection system of the application detects the connectivity of the goaf by detecting ammonia gas. Since the density of ammonia gas is close to the density of gas in the goaf, the gas can be discharged as much as possible while the ammonia gas is discharged, so that dangerous accidents such as explosion and combustion of the gas can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of goaf connectivity detection, and particularly relates to a system and method for detecting goaf connectivity. BACKGROUND

[0002] A goaf is a "cavity" produced by digging mineral resources under the ground. Because a large number of mining fields, chambers and roadways that have not been timely processed remain, the goaf has the characteristics of strong concealment, poor regularity of spatial distribution characteristics, and difficulty in predicting the collapse of the goaf roof, which poses great danger to the safety of new projects that will pass through or pass through the goaf. Therefore, major line projects such as railways and highways often adopt a bypass scheme when passing through a mining area. For mining areas with poor bypass conditions and high costs, reinforcement treatment is needed after the distribution characteristics of the goaf in the range on both sides of the line are checked. Therefore, accurately obtaining the spatial regularity and distribution range of the goaf within the influence range of the line is a prerequisite for bypassing or reinforcement. However, how to reasonably determine the distribution range and spatial regularity of the goaf within the influence range of the line has always been a key technical problem that has puzzled engineering personnel, especially in old mining areas and private mining areas, which often have no data to check, and the spatial regularity of the goaf distribution cannot be directly obtained by collecting mining measured data. Therefore, appropriate and effective survey methods are needed to obtain the detailed geological data required for design.

[0003] Currently, geological radar is mainly used to detect goafs, caves and the like. When the number of objects to be detected is small, the range is small, and the structural differences are large, good results can be obtained by using geological radar for detection. However, when used for detection of irregular goafs (caves) with small medium difference, low water level and wide distribution, the depth of the irregular goaf (cave), the relationship between the hole diameter and the small medium difference of the surrounding stratum, and the small medium difference of the surrounding stratum, result in inaccurate judgment of the position of the irregular goaf (cave), and the detection effect is greatly limited when the geological radar method is used for detection.

[0004] The distribution characteristics of the goaf at a certain position can be directly revealed by drilling. Generally, small goafs are arranged with equal intervals and full arrangement of drilling. As the depth and range of the goaf increase, the depth and number of drilling also increase, resulting in large drilling workload, large waste drilling of full arrangement of drilling, and low effective hole number rate. If the connectivity of the goaf can be effectively explored, the drilling arrangement can be effectively reduced within a certain range, and the survey efficiency can be improved. SF6 tracer gas technology is used to detect the connectivity of the goaf, as disclosed in "Technical Research on SF6 Tracer Gas Technology for Measuring Coal Seam Drilling Extraction Influence Radius" (Energy Technology and Management, Vol. 43, No. 6, 2018, Yin Zeyu). Specifically, SF6 gas is injected into the drill hole, and then the change of the SF6 concentration in the drill hole with time is measured, and the connectivity of the goaf and the extraction radius of the drill hole are determined.

[0005] However, the density of SF6 gas (20℃, 0.1MPa, density 6.00kg / m 3 ) is much greater than the density of air (20℃, 0.1MPa, density 1.21kg / m 3 ), and the density of gas in the goaf (20℃, 0.1MPa, density 0.66kg / m 3 ) is less than the density of air. When the SF6 gas is discharged, a large amount of gas is also discharged, which is prone to cause explosion and other dangerous situations. The detection of SF6 usually uses a gas chromatograph with an electron trap, and the cost of the detection equipment is high. Moreover, the SF6 gas needs to be stored in a high-pressure cylinder, which is not convenient to use and has a high cost. SUMMARY

[0006] Therefore, the present application aims to solve at least one of the above technical problems. To this end, the present application provides a more economical and effective system and method for detecting the connectivity of a goaf.

[0007] To achieve the above object, the technical scheme of the present application is as follows:

[0008] In a first aspect of the present application, a system for detecting the connectivity of a goaf is provided, which comprises a gas injection part configured to inject tracer gas into the goaf through a first borehole in the goaf, the gas injection part comprising: an ammonia storage device for storing ammonia as tracer gas; and a first pipeline configured to connect the ammonia storage device and the first borehole, and a gas collection part configured to collect gas in the goaf through a second borehole in the goaf and detect the presence of the tracer gas, the gas collection part comprising: an ammonia detection device for detecting the presence of ammonia in the collected gas; and a second pipeline configured to connect the second borehole and the ammonia detection device.

[0009] According to an embodiment of the present application, the gas injection part further comprises an ammonia production device configured to produce ammonia in situ, the ammonia production device having an ammonia outlet to communicate with the ammonia storage device.

[0010] According to an embodiment of the present application, the ammonia production device uses an ammonia solution and quicklime to produce ammonia.

[0011] According to an embodiment of the present application, one end of the first pipeline connected to the ammonia storage device extends close to the bottom of the ammonia storage device, and a booster pump is optionally provided between the ammonia storage device and the first borehole.

[0012] According to an embodiment of the present application, in the gas collecting part, a detection reagent or detection paper is arranged inside the ammonia gas detection device, and the second pipeline guides the collected gas to pass through the detection reagent or detection paper.

[0013] According to an embodiment of the present application, the detection reagent or detection paper comprises a substance capable of reacting with ammonia gas and changing color, preferably, the substance is an acid-base indicator.

[0014] According to an embodiment of the present application, the ammonia gas detection device has a shell which is at least partially transparent, so as to observe the detection result.

[0015] According to an embodiment of the present application, the gas collecting part further comprises a post-processing device which is in communication with the ammonia gas detection device, and is used for processing the gas discharged from the ammonia gas detection device.

[0016] According to an embodiment of the present application, the detection system comprises two or more gas collecting parts.

[0017] According to a second aspect of the present application, a goaf connectivity detection method is provided, comprising the following steps: arranging a gas injection borehole and a gas collecting borehole at a distance in a goaf to be detected; injecting a tracer gas into the gas injection borehole, and detecting whether the tracer gas exists at the gas collecting borehole; wherein the tracer gas is ammonia gas.

[0018] According to an embodiment of the present application, the distance between the gas injection borehole and the gas collecting borehole is not greater than 50 m.

[0019] According to an embodiment of the present application, the detection method uses the detection system of the present application described above.

[0020] The goaf connectivity detection system and detection method of the present application use ammonia gas as a tracer gas to detect the connectivity of a goaf. Since the density (20℃, 0.1MPa, density is 0.70kg / m 3 ) of ammonia gas is close to the density of gas in a goaf, the gas in the goaf can be discharged as much as possible while ammonia gas is discharged, so as to avoid dangerous accidents such as explosion and combustion of the gas. Moreover, the detection of ammonia gas can be conveniently detected by using an acid-base indicator, so that the goaf connectivity detection system of the present application has low cost, and is simple and portable. In addition, the goaf connectivity detection system of the present application can be further configured with an ammonia production device to generate ammonia gas in situ, so as to be more convenient to use, high in safety, and further low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 FIG. 1 is a structural schematic diagram of a goaf connectivity detection system of the present application;

[0022] Figure 2 Structure diagram of the gas injection part of an embodiment of the present application;

[0023] Figure 3 Structure diagram of the gas extraction part of an embodiment of the present application;

[0024] Figure 4 Flow chart of the gas extraction part of an embodiment of the present application;

[0025] The figures include: 100-gas injection part; 101-ammonia storage device; 102-first gas outlet pipe; 103-first valve; 104-ammonia production device; 105-reaction reagent; 106-first gas inlet pipe; 107-second valve; 108-gas pressure gauge; 109-boost pump; 110-first sealing plug; 200-gas extraction part; 201-second sealing plug; 202-second gas inlet pipe; 203-third valve; 204-ammonia detection device; 205-ammonia detection reagent; 206-putting table; 207-second gas outlet pipe; 208-alcohol lamp; 301-first drill hole (gas injection drill hole); 302-second drill hole (gas extraction drill hole); 303-gas extraction area. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] The present application will be further described below with reference to the schematic examples shown in the drawings. The advantages of the present application will be more apparent through the following description. The same reference signs in the drawings refer to the same components. The shapes and sizes of the components in the schematic drawings are only for illustration, and cannot be considered to embody the actual shapes, sizes and absolute positions.

[0028] As Figure 1As shown, the goaf 303 is generally a "cavity" formed after the mining of mineral resources, and has the characteristics of strong concealment, poor regularity of spatial distribution characteristics, and difficult prediction of collapse. The gas in the goaf is mainly methane, which flows from the surrounding rock of the goaf. Of course, the gas in the goaf can also include combustible gases such as carbon monoxide, ethane, ethylene and acetylene, among which carbon monoxide is generated by the reaction of coal with oxygen; and ethane, ethylene and other gases are generated after the cracking reaction of coal. If the spatial structure characteristics of the goaf are not clear, it is extremely dangerous to enter the goaf. Therefore, detecting the connectivity of the goaf has great significance for the prevention of safety accidents.

[0029] The gas injection drill hole 301 and the gas extraction drill hole 302 are arranged at a certain distance from the goaf 303 to be detected; the tracer gas ammonia is injected into the gas injection drill hole 301, and the tracer gas ammonia is detected at the gas extraction drill hole 302 to detect the connectivity of the goaf 303.

[0030] The position of the drill hole is not particularly limited, and after the specific position of the goaf to be detected is determined, the drill hole can be arranged on the goaf to be detected. Figure 1 Only one gas injection drill hole 301 and one gas extraction drill hole 302 are shown, and of course, the number of gas injection drill holes 301 and gas extraction drill holes 302 can be two or more. By arranging multiple gas injection drill holes and multiple gas extraction drill holes, a larger area of the goaf can be detected at the same time, and the detection efficiency is improved. The spacing between the drill holes also affects the accuracy of the connectivity detection result.

[0031] If the spacing between the gas injection drill hole and the gas extraction drill hole is too large, not only a large amount of gas needs to be injected into the goaf, but also the goaf can be misjudged as not being connected. If the spacing between the gas injection drill hole and the gas extraction drill hole is too small, the construction amount of the drill hole can be increased, causing unnecessary waste. Preferably, the distance between the gas injection drill hole 301 and the gas extraction drill hole 302 is not greater than 50 m. If the distance between the gas injection drill hole 301 and the gas extraction drill hole 302 is too large, a large amount of tracer gas needs to be injected, and it is not conducive to connectivity discrimination. In addition, the distance between the gas injection drill hole 301 and the gas extraction drill hole 302 is usually not less than 5 m.

[0032] The depth of the drill hole is not particularly limited, and after the specific position of the goaf to be detected is determined, the depth of the drill hole can be ensured to reach the goaf.

[0033] Figure 1The structure of the goaf connectivity detection system of the present application is shown. The detection system comprises a gas injection part 100 and a gas collection part 200 for the drilling of a goaf, the gas injection part 100 is configured to inject a tracer gas into a goaf 303 through a first drilling hole 301 in the goaf, and the gas collection part 200 is configured to collect the gas in the goaf 303 through a second drilling hole 302 in the goaf and detect whether the tracer gas exists. The selection of the tracer gas needs to consider many factors, for example: the goaf originally does not have the tracer gas; the physical and chemical properties of the tracer gas are relatively stable; the tracer gas is not dangerous to the human body; and the tracer gas is easy to detect. In the present application, ammonia is used as the tracer gas, and the above-mentioned gas collection part 200 comprises an ammonia detection device for detecting whether ammonia exists in the collected gas.

[0034] In the above-mentioned goaf connectivity detection system, ammonia is used as the tracer gas, because the density of ammonia is close to the density of the gas in the goaf, which can minimize the emission of gas while emitting ammonia, avoiding dangerous accidents such as explosion and combustion of gas.

[0035] Further reference Figure 1 The gas injection part 100 is in communication with the first drilling hole 301 through the first gas outlet pipe 102, that is, the tracer gas can be injected into the goaf 303 through the first drilling hole 301, and a first sealing plug 110 is arranged at the connection between the first gas outlet pipe 102 and the first drilling hole 301, which is used to realize the sealing between the first gas outlet pipe 102 and the first drilling hole 301 to prevent the tracer gas from leaking. The gas collection part 200 is in communication with the second drilling hole 302 through the second gas inlet pipe 202, that is, the gas in the goaf 303 can be collected through the second drilling hole 302, and whether the injected tracer gas exists can be detected, and a second sealing plug 201 is arranged at the connection between the second gas inlet pipe 202 and the second drilling hole 302, which is used to ensure the sealing between the second gas inlet pipe 202 and the second drilling hole 302 to avoid the leakage of the tracer gas.

[0036] The structure of the gas injection part 100 and the gas collection part 200 will be described in detail below in combination with Figure 2 and 3 .

[0037] Figure 2 The structure of the gas injection part of one embodiment of the present application is shown. The gas injection part 100 comprises a ammonia generating device 104, a first gas inlet pipe 106, a ammonia storage device 101 and a first gas outlet pipe 102 which are in communication in sequence. The ammonia generating device 104 is used to generate ammonia in situ, wherein a reaction reagent 105 capable of generating ammonia is contained, and the ammonia storage device 101 is used to store the generated ammonia.

[0038] Specifically, the reaction reagent 105 can adopt any suitable reaction reagent. More preferably, the reaction reagent is economical, safe and easy to operate. In one embodiment, the reaction reagent 105 can also be an ammonium salt and a base, for example, ammonium chloride and calcium hydroxide react to generate ammonia, calcium chloride and water. In another embodiment, the reaction reagent 105 can also be ammonia and calcium oxide, which react to generate ammonia. Ammonia is prepared by on-site reaction and can be used immediately after preparation, effectively avoiding the cost and risk of ammonia transportation.

[0039] Of course, the ammonia preparation device is not necessary, and an ammonia cylinder can be directly used to liquefy ammonia under pressure.

[0040] The ammonia prepared in the ammonia preparation device 104 enters the ammonia storage device 101 through the first gas inlet pipe 106, and then enters the first borehole through the first gas outlet pipe 102. Since the density of ammonia (20℃, 0.1MPa, density 0.70kg / m 3 ) is less than the density of air (20℃, 0.1MPa, density 1.21kg / m 3 ), the end of the first gas inlet pipe 106 extending into the ammonia storage device 101 is close to the top of the ammonia storage device; the end of the first gas outlet pipe 102 extending into the ammonia storage device 101 is close to the bottom of the ammonia storage device. After the prepared ammonia enters the ammonia storage device 101, the ammonia is at the top of the ammonia storage device 101, gradually displacing the air in the ammonia storage device 101, until the entire ammonia storage device 101 is filled with ammonia. At this time, gas injection can be started, and ammonia enters the goaf directly through the first borehole.

[0041] As shown in the gas injection part, Figure 2 , the second valve 107 and the first valve 103 can be respectively arranged on the pipelines of the first gas inlet pipe 106 and the first gas outlet pipe 102, for controlling the opening and closing of the pipelines.

[0042] As shown in the gas injection part, Figure 2 , a pressure gauge 108 can be arranged on the first gas outlet pipe 102, for displaying the ammonia content in the ammonia storage device 101.

[0043] In addition, a booster pump 109 can be arranged on the first gas outlet pipe 102, which can increase the pressure of the ammonia and then deliver it into the goaf, facilitating the circulation of the ammonia in the goaf.

[0044] Figure 3The structure of the gas collecting part of one embodiment of the present application is shown. The gas collecting part 200 comprises a second gas inlet pipe 202, an ammonia detecting device 204 and a second gas outlet pipe 207 in sequence. The ammonia detecting device 204 is used to detect whether ammonia exists in the collected gas. Preferably, a detection reagent 205 or a detection test paper can be arranged inside the ammonia detecting device 204. The collected gas is guided through the detection reagent or the detection test paper by the second gas inlet pipe 202. The detection reagent or the detection test paper contains a substance capable of reacting with ammonia and changing color. By observing the color change, it can be determined whether ammonia exists in the collected gas.

[0045] In one embodiment, the ammonia detecting device 204 can comprise an acid-base indicator test paper, for example, a test paper soaked with red litmus solution. By using the tracer gas ammonia, the color change of the test paper is observed to determine whether ammonia exists in the collected gas. If the test paper turns blue, it proves that ammonia exists.

[0046] In Figure 3 In the shown gas collecting part, the ammonia detecting device 204 can contain an ammonia detection reagent 205 in the form of a solution, for example, a phenolphthalein solution. One end of the second gas inlet pipe 202 communicates with the second borehole 302, and the other end of the second gas inlet pipe 202 directly extends into the phenolphthalein solution. The other end of the second gas outlet pipe 207 communicates with the top of the ammonia detecting device to discharge the gas after passing through the phenolphthalein solution. By observing the color change of the phenolphthalein solution, it can be determined whether ammonia exists in the collected gas. If the colorless phenolphthalein solution turns red, it proves that ammonia exists.

[0047] Of course, the ammonia detecting device 204 is not limited to the above-mentioned detection reagent or detection test paper for qualitative detection of whether ammonia exists. A detection instrument, for example, a pH meter, can also be used to qualitatively detect whether ammonia exists by using the characteristic that ammonia is alkaline when dissolved in water.

[0048] In the goaf connectivity detection system of the present application, ammonia is used as a tracer gas. The detection of ammonia can be conveniently detected by an acid-base indicator, so that the goaf connectivity detection system of the present application is low in cost and easy to use.

[0049] Preferably, if the color change of the detection reagent or the detection test paper is used to determine whether ammonia exists, the ammonia detecting device 204 can be provided with a shell that is at least partially transparent to facilitate observation of the detection result.

[0050] In Figure 3The gas collection part shown further comprises a post-processing device, which is in communication with the ammonia gas detection device 204 and is used for processing the gas discharged from the ammonia gas detection device 204. The post-processing device can be a burner for processing the discharged other gas, mainly gas, to prevent the gas from being discharged into the air and causing explosion and other hazards. Figure 3 As shown, the post-processing device is an alcohol lamp 208.

[0051] Figure 3 The gas collection part shown further comprises a placement table 206, and the ammonia gas detection device 204 is placed on the placement table 206.

[0052] Figure 3 The second gas inlet pipe 202 can further be provided with a third valve 203 for controlling the opening and closing of the pipeline.

[0053] The material of the first gas inlet pipe 106, the first gas outlet pipe 102, the second gas inlet pipe 202 and the second gas outlet pipe 207 is not particularly limited, as long as it can be used for the delivery of the tracer gas ammonia. For example, the pipeline material can be stainless steel.

[0054] The number of gas collection parts in the detection system can be more than one, for example, two, three, four or even more. By providing multiple gas collection parts, a larger area of the goaf can be simultaneously detected for connectivity, thereby improving the detection efficiency.

[0055] Figure 4 A flow chart of a goaf connectivity detection method according to an embodiment of the present application is shown. As shown, in step S801, first, the gas injection borehole and the gas collection borehole are arranged at a certain distance in the goaf to be detected; then in step S802, the tracer gas, ammonia in the present application, is injected into the gas injection borehole; after a period of time, in step S803, it is detected whether the tracer gas is collected at the gas collection borehole. The detection time for the connectivity of the goaf to be detected is generally limited to within 2h, to ensure the detection efficiency.

[0056] The goaf connectivity detection method of the present application uses ammonia gas to detect the connectivity of the goaf. Since the density of ammonia gas (20℃, 0.1MPa, density 0.70kg / m 3 ) is close to the density of the gas in the goaf, the gas can be discharged as much as possible while the gas is discharged as little as possible, to avoid explosion, combustion and other dangerous accidents of the gas.

[0057] In the method of the present application, the tracer gas ammonia can be obtained by pressurized liquefaction and then transported to the mined-out area to be detected, or can be generated in situ by a reaction and then used after the reaction is completed. Therefore, according to one embodiment, the method of the present application further comprises a step of preparing ammonia before step S802. Further, any suitable reagent can be used to prepare ammonia. For example, ammonium salt and alkali can be used to generate ammonia, or ammonia water and calcium oxide can be used to generate ammonia.

[0058] The detection of the tracer gas ammonia can be performed by a detection reagent or detection paper. Preferably, a detection reagent or detection paper is used, wherein it is particularly preferred to comprise a substance capable of reacting with ammonia and changing color, and by observing the color change, it can be determined whether ammonia exists in the collected gas. For example, an acid-base indicator or acid-base indicator paper can be used. Of course, the detection of the tracer gas ammonia can also be performed by a detection instrument, for example, a pH meter can be used to qualitatively detect whether ammonia exists by using the characteristic that ammonia is alkaline when dissolved in water.

[0059] Considering that the gas collected at the gas extraction borehole can contain not only the tracer gas ammonia but also combustible gas such as gas in the mined-out area to be detected, the method of the present application further comprises a step of post-treatment of the collected gas after step 803, for example, the post-treatment can be performed by combustion to avoid the direct discharge of combustible gas into the air.

[0060] The mined-out area connectivity detection method of the present application can be performed by using the above-mentioned detection system.

[0061] The above-mentioned only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation made according to the content of the present application specification and drawings, or direct / indirect application in other related technical fields is included in the patent protection scope of the present application.

Claims

1. A goaf connectivity exploration system, characterized in that, The detection system comprises a gas injection part and a gas collection part. The gas injection part is configured to inject tracer gas into the goaf through a first borehole in the goaf, and comprises, in sequence, an ammonia preparation device, a first gas inlet pipe, an ammonia storage device, and a first gas outlet pipe. The ammonia preparation device contains a reaction reagent that can react to generate ammonia gas, and is used to prepare ammonia gas as the tracer gas. The ammonia storage device is used to store the ammonia gas. The first gas outlet pipe is configured to connect the ammonia storage device and the first borehole. The gas collection part is configured to collect gas in the goaf through a second borehole in the goaf and detect whether the tracer gas is present, and comprises: An ammonia detection device is used to detect whether ammonia gas is present in the collected gas. The second gas inlet pipe is configured to connect the second borehole and the ammonia detection device. The ammonia detection device is internally provided with a detection reagent or test paper.

2. The probe system of claim 1, wherein, The second gas inlet pipe guides the collected gas through the detection reagent or test paper.

3. The probe system of claim 1, wherein, The detection reagent or test paper contains a substance that can react with ammonia gas and change color.

4. The probe system of claim 1, wherein, The ammonia detection device has a shell that is at least partially transparent.

5. A method of goaf connectivity exploration, characterized in that, A post-processing device is in communication with the ammonia detection device and is used to process gas discharged from the ammonia detection device. The post-processing device is a combustor. The ammonia preparation device uses ammonia water and quicklime to produce ammonia gas. One end of the first gas outlet pipe connected to the ammonia storage device extends close to the bottom of the ammonia storage device. A booster pump is provided between the ammonia storage device and the first borehole.

6. The method of claim 5, wherein the probe is a nucleic acid probe. The detection system comprises two or more gas collection parts. The detection method uses the detection system of any one of claims 1-4 to detect. The detection method comprises the following steps: First and second boreholes are arranged at a distance in the goaf to be detected. Tracer gas is injected into the first borehole. Whether the tracer gas is present is detected at the second borehole. The tracer gas is ammonia gas. The distance between the first borehole and the second borehole is not greater than 50 m.

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