Method for rapidly predicting gas concentration of working face after blowing-out

Abstract

The invention relates to a method for rapidly predicting the gas concentration of a working face after blowing-out, and belongs to the field of coal mine safety. The method comprises the following steps of: acquiring starting and stopping state information of a fan on an excavation working face in real time from a coal mine safety monitoring system; and after judging that the working face stops blowing, immediately starting quick gas concentration prediction after blowing stopping. Recording the blowing-out moment of the working face, and processing the gas concentration information in a period of time before blowing-out as a future gas concentration prediction basic value; calculating the accumulated gas emission amount of the working face in a future period of time, and calculating the average gas concentration of the working face at any time after blowing out according to the gas emission amount; correcting the average gas concentration predicted value of the working face according to the position of the gas sensor on the working face to obtain a meter gas concentration predicted value; and guiding the gas emission time and taking corresponding measures by utilizing the predicted average gas concentration value and the predicted surface gas concentration value. According to the invention, automation of wind stopping prediction can be realized through a gas disaster early warning system or a safety monitoring system.

Description

Technical Field

[0001] The invention belongs to the field of coal mine safety and relates to a method for quickly predicting gas concentration in a working face after ventilation is stopped. Background Art

[0002] During the operation and maintenance of the mining or excavation face, especially during the coal tunnel excavation, sometimes unplanned ventilation stops due to maintenance, sudden power outages or fan failures. For the mining face that is cutting coal, the sources of gas outflow after ventilation stop include coal wall and coal falling. For the mining face during maintenance or non-coal cutting, the main source of gas outflow after ventilation stop is coal wall. Since there is no fresh air volume to carry away the gas in the working face after ventilation stop, the gas in the tunnel continues to accumulate, and the gas concentration will increase rapidly and may reach the limit concentration area of ​​gas explosion, which has the potential risk of gas explosion. Due to the increase in gas concentration, the decrease in oxygen concentration also poses a risk of suffocation to the workers in the mining face. It can be seen that unplanned ventilation stops are extremely dangerous to mines and workers. Unplanned ventilation stops in mining faces are often sudden and urgent, so a simple method that can quickly predict the gas concentration in a short period of time is needed so that managers can make decisions quickly and deal with sudden ventilation stops. Therefore, in response to the sudden ventilation stoppage event at a mining face, the present invention invents a method for quickly predicting gas concentration in the mining face where ventilation stoppage occurs, predicts the gas concentration in the tunnel area after the ventilation stoppage, and provides a theoretical basis for calculating the time required for safe gas discharge. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for quickly predicting the gas concentration of a working face after air stoppage.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for quickly predicting gas concentration in a working face after air is stopped, the method comprising the following steps:

[0006] S1: Collect the start and stop status information of the fan of the mining working face in real time from the coal mine safety monitoring system; when it is determined that the working face has stopped ventilation, immediately start the rapid prediction of gas concentration after ventilation stops;

[0007] S2: Record the time when the working face stops ventilation, and process the gas concentration information before the ventilation stops as the basic value C for predicting the future gas outflow 0 ;

[0008] S3: Predict the basic value C based on the gas outflow 0 Calculate the cumulative gas outflow Q of the working face in the future period, and calculate the average gas concentration of the working face at any time after the air is stopped based on the gas outflow;

[0009] S4: Correcting the predicted value of average gas concentration of the working face according to the position of the gas sensor on the working face to obtain the predicted value of surface gas concentration;

[0010] S5: Use the predicted average gas concentration value and surface gas concentration value to guide the gas emission time and take corresponding measures.

[0011] Furthermore, in S2, the method for determining whether the working face has stopped ventilation is that all the main and standby fans are powered off.

[0012] Further, in S2, the gas concentration information of a period of time before the wind stop is used, which is characterized by using the average gas concentration C of the five minutes before the wind stop. 0 As the basic value for wind stop prediction.

[0013] Further, in S3, the calculation method of the cumulative gas emission of the working face in the future period of time is:

[0014] Q=C 1 sl / 100+C 0 tf / 100

[0015] In the formula, C 0 is the average gas concentration five minutes before the wind stops; C 1 is the gas concentration at the time of air stoppage; t is the air stoppage time, in min; Q is the gas outflow during the air stoppage, in m 3 ; f is the air volume of the working surface, unit is m 3 / min; s is the cross-sectional area of ​​the tunnel, in m 2 ; l is the distance between the predicted location and the working surface, in meters.

[0016] Furthermore, in S3, the method for calculating the predicted value of the average gas concentration for a period of time after the air is stopped is:

[0017] C 2 =(C 0 tf+C 1 sl) / (C 0 tf+100sl)

[0018] In the formula, C 2 It is the predicted value of average gas concentration after ventilation is stopped.

[0019] Furthermore, in S4, the average gas concentration prediction value correction method is:

[0020] C 4 =kC 2

[0021] In the formula, C 4 is the surface gas concentration value after the air is stopped at the working face; k is the surface gas concentration correction coefficient.

[0022] Further, the method for determining the surface gas concentration correction coefficient is:

[0023] S41: Use a handheld gas concentration meter to measure the average gas concentration C of the section where the sensor is suspended 3 ;

[0024] S42: Record the gas concentration of the sensor at the same time C 5 ;

[0025] S43: Calculate the gas concentration correction factor k i =C 5 / C 3 ;

[0026] S44: Repeat S41 to S43 five times and calculate the correction coefficient k each time i , and find the fifth-order correction coefficient k i The average value of is used to obtain the final gas concentration correction coefficient k;

[0027] Furthermore, in S41, the average gas concentration C 3 The determination method is:

[0028] S411: Divide the tunnel section into 9 to 16 grids according to the size of the tunnel cross-section;

[0029] S412: The gas concentration measuring instrument is placed in each grid for the same time to measure the gas concentration of each grid;

[0030] S413: Calculate the average gas concentration of each grid as the average gas concentration C of the section 3 .

[0031] The beneficial effect of the present invention is that the gas concentration change law after the air stoppage and the quantitative functional relationship between the gas outflow and the gas concentration over time can be quickly obtained through the gas concentration before the air stoppage, and then the specific time when the gas concentration exceeds the limit or reaches a certain value can be obtained, which provides a basis for taking subsequent air stoppage measures and prevents the occurrence of gas explosions or gas asphyxiation accidents. The method is conducive to realizing the automation of air stoppage prediction through a gas disaster early warning system or a safety monitoring system, and has the advantages of few parameters, high degree of automation, fast prediction speed, and relatively safe prediction results.

[0032] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0034] Figure 1 A flow chart of a method for quickly predicting gas concentration in a working face after air stoppage provided by an embodiment of the present invention;

[0035] Figure 2 A graph showing the change of gas concentration over time at a working surface after air is stopped provided in an embodiment of the present invention; DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0037] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0038] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are 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, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0039] The present invention provides a method for quickly predicting gas concentration in a working face after air is stopped. Figure 1 As shown, the following steps are included:

[0040] S1: Collect the start and stop status information of the mining face fan in real time from the coal mine safety monitoring system; when it is determined that the working face has stopped ventilation, immediately start the rapid prediction of gas concentration after ventilation stops.

[0041] S2: Record the time when the ventilation stops at the working face, and process the gas concentration information before the ventilation stops as the basic value C for predicting the future gas outflow 0 ;

[0042] S3: Calculate the cumulative gas outflow Q of the working face in the future, and calculate the average gas concentration of the working face at the air stop time t based on the gas outflow;

[0043] S4: Correcting the predicted value of average gas concentration of the working face according to the position of the gas sensor on the working face to obtain the predicted value of surface gas concentration;

[0044] S5: Use the predicted gas concentration to guide the gas emission time and take corresponding measures.

[0045] The technical principle of the present invention is to use the characteristics that the gas emission volume is basically unchanged or does not change much in a short period of time (for example, half an hour, 1 hour) after the working face stops the ventilation, and predict the gas emission volume after the ventilation stops by the gas emission volume in the period before the ventilation stops, and then calculate the average gas concentration real value and its apparent gas concentration value corresponding to different prediction times by parameters such as coal body cross-sectional area and tunnel length. The present invention is suitable for predicting the gas emission volume in a short period of time (for example, half an hour, 1 hour) after the ventilation stops, and in coal mine practice, the ventilation stops often have the characteristics of suddenness and urgency, and the ventilation stops generally will not be too long (mostly half an hour to 2 hours), and it is often necessary to make a quick decision and take corresponding measures after the ventilation stops, so a method with fast response, simplicity and convenience that can immediately give a prediction of the trend of gas concentration changes after ventilation stops is needed, and the method is required to have a high degree of automation and less manual intervention, and be able to predict the gas concentration within a certain time range. The present invention has the advantages of being simple, not requiring advance investigation of the gas emission attenuation law, and being conducive to realizing automatic air stop prediction through software. The present invention is applicable to both excavation working faces and coal mining working faces, as well as to chambers, tunnels and other locations, and has the advantage of a wide range of adaptability.

[0046] In this embodiment, the method for determining whether the working face has stopped ventilation as described in S1 is that all the main and standby fans are powered off.

[0047] In S2, the gas concentration information before the air stop is used, which is characterized by using the average gas concentration C of the five minutes before the air stop. 0 As the basic value for wind stop prediction, the average value C 0 The calculation method is:

[0048]

[0049] Where n is the number of gas concentration samples five minutes before the wind stop; i is 1, 2, 3, etc.; C i is the gas concentration.

[0050] In order to more clearly show the process of obtaining the basic value of gas concentration prediction, the following example is given: Taking the excavation working face of the south wing of a mine as an example, the gas concentration before and after the air is stopped is shown in Table 1.

[0051] Table 1

[0052]

[0053]

[0054] In this case, the south wing air intake tunnel excavation face stopped ventilation at 20:46:52 on 2024-6-22. The average gas concentration during the five minutes before the ventilation stop, i.e., 20:41:53 to 20:46:52, should be taken as the predicted basic value C of gas outburst after ventilation stop. 0 , that is, C 0 =0.27%.

[0055] In S3, the calculation method of the cumulative gas outburst volume of the working face in the future period is:

[0056] Q=C 1 sl / 100+C 0 tf / 100(2)

[0057] In the formula, C 0 is the average gas concentration five minutes before the wind stop; t is the wind stop time, in min; Q is the gas outflow during the wind stop, in m 3 ; f is the air volume of the working surface, unit is m 3 / min,C 1 is the gas concentration at the moment of air stop; l is the distance between the working surface sensor and the working surface, in meters;

[0058] In order to more clearly show the calculation method of the cumulative gas outflow in S3 of this embodiment, an example is given:

[0059] Using the gas outburst prediction basic value obtained from the S2 case in this example, the air volume f of the working face of the south wing air inlet tunnel is set to 360m 3 / min,s=20m 2 , l = 5m Substituting into formula (2), we can get the law of cumulative gas emission changing with time:

[0060] Q=360×0.266×t / 100+100×0.28 / 100=0.95t+0.28

[0061] In S3, the method for calculating the predicted value of the actual gas concentration for a period of time after the air is stopped is:

[0062] C 2 =(C 0 tf+C 1 sl) / (C 0 tf+100sl)(3)

[0063] Where C 2 is the predicted value of the actual gas concentration after the ventilation is stopped; s is the cross-sectional area of ​​the tunnel, in m 2 ;

[0064] In order to more clearly demonstrate the calculation method of the actual gas concentration prediction value in S3 of this embodiment, an example is given:

[0065] Using the equation (3) of the cumulative gas outflow after ventilation shutdown obtained in the S4 case in this example, the cross-sectional area of ​​the south wing air inlet tunnel is s = 20m 2 , l = 5m and substituting into formula (3), we can obtain the time variation characteristics of the predicted value of the actual gas concentration after the air is stopped:

[0066] C 2 =(0.95t+0.28) / (0.95t+100)(4)

[0067] Using formula (4), we can get the curve of the predicted value of the actual gas concentration after the air is stopped and the change with the air stop time as follows: Figure 2 As shown by Figure 2 It can be seen that gas accumulates rapidly after the ventilation is stopped at the working face: at a distance of 5m from the working face, the gas concentration exceeds 5% after 6 minutes of ventilation, reaches 8.1% after 10 minutes of ventilation, further increases to 21.8% after 30 minutes, and reaches 36.09% after 60 minutes of ventilation.

[0068] In S4, the surface gas concentration correction method is:

[0069] C 4 =kC 2

[0070] Where C 4 is the predicted value of gas concentration after correction after the ventilation of the working face is stopped, that is, the surface gas concentration value; k is the correction coefficient;

[0071] Whether the gas concentration exceeds the limit is generally determined by the working face sensor, and the sensor is generally suspended in the middle and upper part of the tunnel. Therefore, the gas concentration measured by the sensor is generally larger than the actual gas concentration average.

[0072] The correction coefficient k is determined as follows:

[0073] S41: Use a handheld gas concentration meter to measure the average gas concentration C of the section where the sensor is suspended 3 ;

[0074] S42: Record the gas concentration C of the sensor at the same time 5 ;

[0075] S43: Calculate the gas concentration correction coefficient k i =C 5 / C 3 ;

[0076] S44: Repeat the above steps 5 times to find the correction coefficient k each time i , and calculate the average value of 5 times to determine the final gas concentration correction coefficient k.

[0077] The average gas concentration of S41 is C 3 The determination method is:

[0078] S411: Divide the tunnel section into 9 to 16 grids according to the size of the tunnel section;

[0079] S412: The gas concentration measuring instrument is placed in each grid for the same time to measure the gas concentration of each grid;

[0080] S413: Finally, the average gas concentration of each grid is calculated as the average gas concentration C of the section. 3 .

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for quickly predicting gas concentration in a working face after air stoppage, characterized in that: The method comprises the following steps: S1: Collect the start and stop status information of the fan of the mining working face in real time from the coal mine safety monitoring system; when it is determined that the working face has stopped ventilation, immediately start the rapid prediction of gas concentration after ventilation stops; S2: Record the time when the ventilation is stopped at the working face, and process the gas concentration information for a period of time before the ventilation is stopped as the basic value C0 for predicting the future gas outflow; S3: Calculate the cumulative gas outflow Q of the working face in the future period based on the predicted basic value of gas outflow C0, and calculate the average gas concentration of the working face at any time after the air is stopped based on the gas outflow; S4: Correcting the predicted value of average gas concentration of the working face according to the position of the gas sensor on the working face to obtain the predicted value of surface gas concentration; S5: Use the predicted average gas concentration value and surface gas concentration value to guide the gas emission time and take corresponding measures.

2. The method for quickly predicting gas concentration in a working face after air stoppage according to claim 1 is characterized in that: In S2, the method for determining whether the working face has stopped ventilation is that all the main and standby fans are powered off.

3. The method for quickly predicting gas concentration in a working face after air stoppage according to claim 1 is characterized in that: In S2, the use of the gas concentration information of a period of time before the wind stoppage is characterized in that the average gas concentration C0 five minutes before the wind stoppage is used as the basic value for wind stoppage prediction.

4. The method for quickly predicting gas concentration in a working face after air stoppage according to claim 1 is characterized in that: In S3, the calculation method of the cumulative gas outflow volume of the working face in the future period of time is: Q=C1sl / 100+C0tf / 100 In the formula, C0 is the average gas concentration five minutes before the wind stop; C1 is the gas concentration at the wind stop; t is the wind stop time, in min; Q is the gas outflow during the wind stop, in m 3 ; f is the air volume of the working surface, unit is m 3 / min; s is the cross-sectional area of ​​the tunnel, in m 2 ; l is the distance between the predicted location and the working surface, in meters.

5. The method for rapid prediction of gas concentration in a working face after air stoppage according to claim 1 is characterized in that: In S3, the method for calculating the predicted value of the average gas concentration in the future period after the air is stopped is: C2=(C0tf+C1sl) / (C0tf+100sl) Where C2 is the predicted value of the average gas concentration after ventilation is stopped.

6. The method for rapid prediction of gas concentration in a working face after air stoppage according to claim 1 is characterized in that: In S4, the average gas concentration prediction value correction method is: C4=kC2 Where, C4 is the surface gas concentration value after the air flow is stopped at the working face; k is the surface gas concentration correction coefficient.

7. A method for quickly predicting gas concentration in a working face after air stoppage according to claim 6, characterized in that: The method for determining the surface gas concentration correction coefficient is: S41: Use a handheld gas concentration meter to measure the average gas concentration C3 of the section where the sensor is suspended; S42: Record the gas concentration of the sensor at the same moment C5; S43: Calculate the gas concentration correction factor k i =C5 / C3; S44: Repeat S41 to S43 five times and calculate the correction coefficient k each time i , and find the fifth-order correction coefficient k i The average value of the gas concentration is obtained to obtain the final gas concentration correction coefficient k.

8. According to claim 7, a method for quickly predicting gas concentration in a working face after air stoppage, characterized in that: In S41, the method for determining the average gas concentration C3 is: S411: Divide the tunnel section into 9 to 16 grids according to the size of the tunnel cross-section; S412: The gas concentration measuring instrument is placed in each grid for the same time to measure the gas concentration of each grid; S413: Calculate the average gas concentration of each grid as the average gas concentration C3 of the section.

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