A multi-gas monitoring method for early warning of underground coal mine fire

Abstract

The invention discloses a multi-gas monitoring method for early warning of underground coal mine fire, which relates to the technical field of coal mine fire monitoring, and comprises the following steps: S1: taking coal seam coal samples according to the coal seam coal quality characteristics, and conducting simulation experiments on the production law of spontaneous combustion gas products; S2: using CO sensors, C2H4 sensors and C2H2 sensors to monitor spontaneous combustion in goaf areas according to the selected spontaneous combustion marker gas and marker gas index; S3: arranging marker gas sensors for U-shaped ventilation working faces and Y-shaped ventilation working faces; S4: when the data is abnormal, the marker gas sensor alarms, and the signal is transmitted to the underground switch through the monitoring substation. The multi-gas monitoring method for early warning of underground coal mine fire has short analysis time, sensitive signals, accurate results, and can be connected to the monitoring and surveillance system of the mine to realize data sharing. It is simple to use and operate, with low investment and convenient maintenance.

Description

Technical Field

[0001] The invention relates to the technical field of coal mine fire monitoring, and in particular to a coal mine underground fire early warning multi-gas monitoring method. Background Art

[0002] The spontaneous combustion process of coal can be divided into three stages, namely the latent period, the self-heating period and the combustion period; there are generally no obvious signs during the latent period; during the self-heating period, the oxidation rate of coal accelerates, the oxygen content in the air decreases, and the carbon monoxide and carbon dioxide content increases. This period is easy to make early forecasts and take preventive measures; according to the different levels of spontaneous combustion danger of floating coal in the goaf, the goaf can be divided into a heat dissipation zone, an oxidation zone and a suffocation zone, namely the "three zones" of spontaneous combustion. The distribution characteristics of the "three zones" of spontaneous combustion are an important basis for preventing and controlling spontaneous combustion in goafs. Most of the spontaneous combustion of coal in goafs occurs in the oxidation zone among the "three zones" of spontaneous combustion in goafs;

[0003] With the application of gas chromatography technology in underground coal mines, the mine bundle pipe monitoring system has become an indispensable technical equipment for coal mine fire prevention and extinguishing. It can monitor the goaf and confined areas in real time, and collect and analyze the index gas in the monitoring area, so as to achieve early warning of spontaneous combustion of coal, which plays an important role in the prevention and control of spontaneous combustion fires in mines; the bundle pipe monitoring system is the main analysis tool used in the marker gas analysis method, mainly composed of gas analyzer (gas chromatograph) and its auxiliary equipment, gas circuit control cabinet, vacuum pump, gas-water separator box, bundle pipe branch box, bundle pipe cable, etc.; by laying bundle pipe cables from the monitoring room to the monitoring location, using the vacuum pump to take the analysis gas to the gas circuit control cabinet, waiting for detection, the gas circuit control solenoid valves of the gas circuit control cabinet act in sequence according to the start-up sequence set in the monitoring computer, and send the gas at the underground monitoring location into the analysis instrument, and display the analysis data on the monitoring computer to analyze the oxidation stage of the residual coal at the underground monitoring location;

[0004] However, the existing mine bundle pipe monitoring system has the following problems when in use:

[0005] The monitoring data has a certain time lag; the bundle tube detection system can monitor the goaf in real time, but the monitoring data displayed by the system is not the current time, but a certain time in the past. There are two main reasons for this: first, it takes a certain amount of time for the gas sample to be transmitted from the monitoring area to the analysis instrument, and in order to ensure the accuracy of the gas sample, the pipeline must be flushed. Depending on the length of the pipeline, the time required for flushing the pipeline will vary, generally about 10 minutes; second, for the gas chromatograph, it also takes a certain amount of time to analyze a single gas sample;

[0006] The management and maintenance of the pipeline in the later stage are difficult; the pipeline is to ensure the purity of the gas sample. The gas sample must be collected from the probe and sent to the chromatograph through the pipeline without contamination. If the gas sample is contaminated, the results detected by the bundle tube detection system cannot correctly reflect the changes in the spontaneous combustion of coal in the monitoring area, which will lead to misjudgment by management personnel and serious consequences. Therefore, the bundle tube system has very high requirements for the sealing of the pipeline; however, in the actual application of the bundle tube system in coal mines, no matter whether the laid bundle tube pipeline is arranged at the top, middle or bottom of the tunnel, it will be affected by the mine. The influence of pressure is very likely to damage the pipeline and cause gas leakage. Moreover, the laying distance of the pipeline is often several thousand meters. Therefore, some joints will inevitably be formed in the pipeline, and these joints are also potential gas leakage hazards. It is very difficult to find the fault point of the pipeline. The maintenance personnel are required to search the bundled pipe pipeline from beginning to end. The bundled pipe pipeline is not only long in distance, but also numerous in number. Maintenance is time-consuming and laborious, and the overall efficiency is low, which affects the real-time monitoring of underground coal mine gas by the coal mine gas bundle pipe monitoring device, and may cause safety accidents.

[0007] In order to solve the above problems, a multi-gas monitoring method for underground coal mine fire prediction is proposed. Summary of the invention

[0008] The purpose of the present invention is to provide a multi-gas monitoring method for coal mine underground fire warning, so as to solve the problem that the existing mine bundle pipe monitoring system proposed in the above background technology has a certain time lag in monitoring data and is difficult to manage and maintain the pipeline in the later stage. The technical solution of the present invention aims at the technical problem that the existing technical solution is too single, and provides a solution that is significantly different from the existing technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a multi-gas monitoring method for early warning of underground coal mine fire, the monitoring method comprising the following steps:

[0010] S1: Take coal samples according to the coal seam coal quality characteristics, conduct simulation experiments on the production rules of spontaneous combustion gas products, and select the spontaneous combustion marker gas and marker gas index suitable for this coal seam;

[0011] S2: For the selected spontaneous combustion sign gas and sign gas index, CO sensor, C2H4 sensor and C2H2 sensor are used to monitor the spontaneous combustion in the goaf. The alarm value of each sign sensor is determined according to the sign gas product concentration and the corresponding temperature value obtained from the coal spontaneous combustion simulation gas product analysis experiment;

[0012] S3: Arrange the signature gas sensors for the U-shaped ventilation working face and the Y-shaped ventilation working face. The signature gas sensors are arranged at the upper corner of the return air of the U-shaped ventilation working face, and the signature gas sensors are arranged in the Y-shaped ventilation working face according to the air leakage distribution status of the goaf;

[0013] S4: When the data is abnormal, the iconic gas sensor alarms, and the signal is transmitted to the downhole switch through the monitoring substation, and then transmitted to the ground through the downhole switch. Based on this, timely adjustments are made to make corresponding emergency responses.

[0014] Preferably, the coal spontaneous combustion simulation gas product analysis experiment is to subject a certain amount of coal sample to programmed temperature increase under laboratory conditions, cyclically analyze the type and concentration of gas products in each temperature range and the temperature change characteristics of the coal sample, and based on this, select the applicable spontaneous combustion marker gas and its indicators.

[0015] Preferably, the measurement range of the CO sensor is 0 to 1000×10 -6 The measurement range of C2H4 sensor is 0~1000×10 -6 、The measurement range of C2H2 sensor is 0~100×10 -6 .

[0016] Preferably, the method for confirming the air leakage distribution state of the goaf in the Y-shaped ventilation working face is:

[0017] Conduct SF6 tracer gas release experiments in Y-type ventilation working surfaces;

[0018] Determine the width of the air leakage zone along the gob-side tunnel;

[0019] Marking gas sensors are arranged within the air leakage zone and close to the side of the goaf retained tunnel.

[0020] Preferably, the signature gas sensor is connected to the coal mine underground safety monitoring system and, as a subsystem of the whole mine safety monitoring system, performs data aggregation, sharing, and fusion analysis with the safety monitoring system.

[0021] Preferably, the underground switch is transmitted to the ground switch via optical fiber or ring network, and is connected to the WEB server and database server of the ground production safety monitoring center.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. In order to solve the problems of long bundle pipe lines, many joints, and inaccurate results caused by gas leakage in the traditional bundle pipe monitoring process, the present invention uses sensors to monitor the natural combustion characteristic gas in the goaf. When the characteristic gas concentration is too high, the concentration variable is converted into an output signal corresponding to it. The signal is transmitted to the switch and transmitted to the ground through optical fiber or ring network. Compared with the traditional bundle pipe monitoring process, the gas transmission time and instrument analysis time are reduced, and the monitoring accuracy is significantly improved. At the same time, due to the different coal qualities of different coal mines and different coal seams, the arrangement of characteristic gas sensors for working faces of different ventilation systems is determined through tracer gas release experiments and other methods, and it is more scientific and reasonable to select characteristic gas sensors based on the conclusions drawn from the coal natural combustion simulation gas product analysis experiment;

[0024] 2. The present invention can be used as an independent fire monitoring and early warning system, or it can be connected to the coal mine underground safety monitoring system as a subsystem of the whole mine safety monitoring system, and perform data aggregation, sharing, and fusion analysis with the safety monitoring system, further improving the coal mine underground complex disaster monitoring and comprehensive risk analysis and assessment capabilities;

[0025] 3. Compared with the traditional bundle tube monitoring process, the present invention does not need to lay traditional bundle tube equipment such as bundle tube pipelines, drainage devices, sampling boxes, etc. deep in the goaf. It only needs to arrange the signature gas sensor at the return air corner of the working face; the signature gas sensor is connected to the mine safety monitoring system; the signature gas sensor is arranged at the return air corner of the working face as the coal mining working face advances, and the natural combustion of residual coal in the goaf of the working face can be monitored; at the same time, the number of equipment invested is small, the investment is low, and the equipment maintenance workload is reduced, and it can be maintained together with the coal mine safety monitoring system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the multi-gas monitoring process for early warning of underground fire in coal mines according to the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the flow chart of the iconic gas sensor arrangement of the present invention;

[0028] Figure 3 This is a schematic diagram of the layout of the gas sensors on the U-shaped ventilation working surface of the present invention;

[0029] Figure 4 It is a schematic diagram of the arrangement of the iconic gas sensors on the Y-shaped ventilation working surface of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] See also Figure 1-Figure 4 The present invention provides a technical solution: a multi-gas monitoring method for early warning of underground coal mine fire, the monitoring method comprising the following steps:

[0032] S1: Take coal samples according to the coal seam coal quality characteristics, conduct simulation experiments on the production rules of spontaneous combustion gas products, and select the spontaneous combustion marker gas and marker gas index suitable for this coal seam;

[0033] S2: For the selected spontaneous combustion sign gas and sign gas index, CO sensor, C2H4 sensor and C2H2 sensor are used to monitor the spontaneous combustion in the goaf. The alarm value of each sign sensor is determined according to the sign gas product concentration and the corresponding temperature value obtained from the coal spontaneous combustion simulation gas product analysis experiment;

[0034] S3: Arrange the signature gas sensors for the U-shaped ventilation working face and the Y-shaped ventilation working face. The signature gas sensors are arranged at the upper corner of the return air of the U-shaped ventilation working face, and the signature gas sensors are arranged in the Y-shaped ventilation working face according to the air leakage distribution status of the goaf;

[0035] The method for confirming the air leakage distribution status of the goaf in the Y-type ventilation working face is:

[0036] Conduct SF6 tracer gas release experiments in Y-type ventilation working surfaces;

[0037] Determine the width of the air leakage zone along the gob-side tunnel;

[0038] Arrange landmark gas sensors within the air leakage zone and close to the side of the gob retaining tunnel;

[0039] Since the production conditions and ventilation conditions of different working faces are not the same, the airflow flowing through the "three zones" of spontaneous combustion in the goaf will flow out from the return air corner. By setting a landmark gas sensor at the return air corner of the working face, the CO, C2H4, and C2H2 gas concentrations in the spontaneous combustion process of the residual coal in the goaf can be monitored, thereby realizing early monitoring and early warning of natural combustion of the residual coal in the goaf. At the same time, only after determining the air leakage distribution status of the goaf of the Y-type ventilation working face and mastering the distribution law of the leakage flow field, can the location of the landmark gas sensor of the Y-type ventilation working face be determined.

[0040] S4: When the data is abnormal, the signature gas sensor alarms, and the signal is transmitted to the underground switch through the monitoring substation, and then transmitted to the ground through the underground switch and used as a basis for timely regulation and control, and corresponding emergency response; the signature gas sensor is connected to the coal mine underground safety monitoring system, as a subsystem of the whole mine safety monitoring system, and performs data aggregation, sharing, and fusion analysis with the safety monitoring system; the underground switch transmits to the ground switch through optical fiber or ring network, and is connected to the WEB server and database server of the ground safety production monitoring center; it is convenient to connect to the mine monitoring system to realize data sharing, and at the same time, it requires less investment and is easy to maintain;

[0041] The coal spontaneous combustion simulation gas product analysis experiment is to program a certain amount of coal sample under laboratory conditions, cyclically analyze the type and concentration of gas products in each temperature range and the temperature change characteristics of the coal sample, and then select the appropriate spontaneous combustion marker gas and its index; the measurement range of the CO sensor is 0~1000×10 -6 The measurement range of C2H4 sensor is 0~1000×10 -6 、The measurement range of C2H2 sensor is 0~100×10 -6 .

[0042] The contents not described in detail in this specification belong to the prior art known to the professional and technical personnel in this field. In the description of the present invention, unless otherwise specified, "multiple" means two or more; the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-gas monitoring method for early warning of underground coal mine fire, characterized in that: The monitoring method comprises the following steps: S1: Take coal samples according to the coal seam coal quality characteristics, conduct simulation experiments on the production rules of spontaneous combustion gas products, and select the spontaneous combustion marker gas and marker gas index suitable for this coal seam; S2: For the selected spontaneous combustion sign gas and sign gas index, CO sensor, C2H4 sensor and C2H2 sensor are used to monitor the spontaneous combustion in the goaf. The alarm value of each sign sensor is determined according to the concentration of the sign gas product and the corresponding temperature value obtained by the coal spontaneous combustion simulation gas product analysis experiment. The coal spontaneous combustion simulation gas product analysis experiment is to program a certain amount of coal sample under laboratory conditions, cyclically analyze the type and concentration of gas products in each temperature section and the temperature change characteristics of the coal sample, and select the appropriate alarm value accordingly; S3: Arrange the signature gas sensors for the Y-shaped ventilation working face, wherein the signature gas sensors are arranged in the Y-shaped ventilation working face according to the air leakage distribution state of the goaf; The method for confirming the air leakage distribution state of the goaf in the Y-type ventilation working face is: Conduct SF6 tracer gas release experiments in Y-type ventilation working surfaces; Determine the width of the air leakage zone along the gob-side tunnel; Arrange landmark gas sensors within the air leakage zone and close to the side of the gob retaining tunnel; S4: When the data is abnormal, the iconic gas sensor alarms, and the signal is transmitted to the downhole switch through the monitoring substation, and then transmitted to the ground through the downhole switch. Based on this, timely adjustments are made to make corresponding emergency responses.

2. A coal mine underground fire early warning multi-gas monitoring method according to claim 1, characterized in that: The measurement range of the CO sensor is 0~1000×10 -6 The measurement range of C2H4 sensor is 0~1000×10 -6 、The measurement range of C2H2 sensor is 0~100×10 -6 .

3. A coal mine underground fire early warning multi-gas monitoring method according to claim 1, characterized in that: The iconic gas sensor is connected to the coal mine underground safety monitoring system and, as a subsystem of the entire mine safety monitoring system, performs data aggregation, sharing, and fusion analysis with the safety monitoring system.

4. A coal mine underground fire early warning multi-gas monitoring method according to claim 1, characterized in that: The underground switch is transmitted to the ground switch via optical fiber or ring network, and is connected to the WEB server and database server of the ground production safety monitoring center.

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