A method for obtaining a dynamic threshold for gas concentration early warning and regulation in a coal mining face

Abstract

The present invention belongs to the field of gas concentration risk warning and safety prevention and control in coal mining faces, and specifically relates to a method for obtaining dynamic thresholds for warning and regulating the gas concentration in coal mining faces. The method includes the following steps: S100: Record the monitoring data of the gas concentration in the coal mining face every 20 minutes and continuously monitor and count for 20 days; S200: Calculate the characteristic time points of the time-delay response of the gas concentration; S300: Calculate the delay time and viscous increase time of the time-delay response of the gas concentration; S400: Calculate the real-time rate of the time-delay response of the gas concentration; S500: Calculate the real-time rate of the gas concentration in the viscous increase response stage; S600: Calculate the dynamic threshold for warning and regulating the gas concentration in the coal mining face during the production process. The present invention can effectively address the time-delay aftereffect problem in the process of regulating the gas concentration in coal mining faces and achieve real-time and accurate evaluation and warning of the gas concentration in coal mining faces.

Description

Technical Field

[0001] The present invention belongs to the field of gas concentration risk warning and safety prevention and control in coal mining faces, and specifically relates to a method for obtaining dynamic thresholds for gas concentration warning and regulation in coal mining faces. Background Art

[0002] Gas disasters are one of the five major disasters in coal mines. Among gas disasters, although gas overlimit accidents have relatively less impact, they are the most frequent and one of the most difficult production safety problems for safety workers to manage. Power-off and production suspension after overlimit greatly affect the safe and efficient production of enterprises. The warning and regulation threshold of gas concentration is an important parameter for dynamic risk assessment and warning of gas disasters in coal mining faces, and can provide a scientific and reasonable regulation timing for the prevention and control of gas overlimit accidents, which is of great significance for ensuring coal mine production safety.

[0003] There are double lags in time and space in the gas concentration monitoring of coal mining faces: the gas concentration reflects the distribution of gas in a three-dimensional space, while the monitoring data of sensors is only the gas concentration at a certain point in space, so there is a spatial lag in the monitoring data; production activities such as ventilation and gas drainage are often far from the working positions where gas concentration sensors are located, and it is difficult for the change of gas concentration caused by activity factors to be transmitted to the sensors in the first time, so there is a time lag in the monitoring data.

[0004] Currently, the general fixed value of 1% is used as the warning and regulation threshold for gas concentration in coal mining faces. When the gas concentration reaches or approaches 1%, regulation measures are implemented. However, due to the existence of delay lag effects, even if regulation is carried out immediately, the gas concentration cannot be immediately reduced, and gas overlimit becomes inevitable; in addition, the distances between the gas concentration and 1% at different times are different, and the time lag response forms such as the change rate of gas concentration after different measures are implemented are also different, so the time required for the gas concentration to reach 1% must be different. Setting the warning and regulation threshold to a fixed 1% and dealing with all changes with the same method, the failure of regulation is also inevitable. Summary of the Invention

[0005] In order to solve the problem that the fixed warning and regulation threshold of gas concentration cannot cope with the lag effect in gas regulation measures in coal mining faces, the present invention provides a method for obtaining dynamic thresholds for gas concentration warning and regulation in coal mining faces.

[0006] The present invention adopts the following technical solutions: A method for obtaining a dynamic threshold for warning and regulating the gas concentration in a coal mining face, comprising the following steps: S100: Record the monitoring data of the gas concentration in the coal mining face every 20 minutes, and continuously monitor and count for 20 days; S200: Calculate the characteristic time points of the time-delay response of the gas concentration according to the continuously monitored data; S300: Calculate the delay time and the viscous increase time of the time-delay response of the gas concentration according to the characteristic time points of the time-delay response of the gas concentration; S400: Calculate the real-time rate of the time-delay response of the gas concentration, that is, the delay rate, according to the real-time state of the gas concentration during the production process; S500: Calculate the real-time rate of the gas concentration in the viscous increase response stage, that is, the viscous increase rate, by using the delay rate and the viscous increase time of the time-delay response of the gas concentration; S600: Calculate the dynamic threshold for warning and regulating the gas concentration in the working face during the production process by using the delay time, the delay rate, the viscous increase time and the viscous increase rate of the time-delay response of the gas concentration.

[0007] In step S200, the characteristic time points of the time-delay response of the gas concentration in the coal mining face include the initial moment of the time-delay response of the gas concentration, the end moment of the time-delay response, and the end moment of the viscous increase response stage.

[0008] The specific calculation process of step S200 is as follows:

[0009] S201: Let x ( t i ) be the gas concentration in the coal mining face at the moment t i in the statistical data. When t i satisfies formula 1, i = 0, 1, 2, …, denote t i = t 0 , which is the initial moment of the time-delay response of the gas concentration;

[0010] (1)

[0011] S202: When t i satisfies formula 2, denote t i = t c , which is the end moment of the time-delay response of the gas concentration;

[0012] (2)

[0013] S203: When t i satisfies formula 3, denote ti = t n+ , which is the end time of the viscous increase response stage of the gas concentration;

[0014] (3).

[0015] The specific calculation process of step S300 is as follows:

[0016] S301: The delay time of the time lag response of the gas concentration in the coal mining face T c As shown in formula 4,

[0017] T c =t c - t 0 (4)

[0018] S302: The viscous increase time of the time lag response of the gas concentration in the coal mining face T n+ As shown in formula 5,

[0019] T n+ = t n+ - t c (5).

[0020] The specific calculation process of step S400 is: using the real-time concentration of gas x ( t j-2 ), x ( t j-1 ) and x ( t j ), j = 0, 1, 2, …, calculate the real-time rate of the time lag response of the gas concentration, that is, the lag rate v c ( t ), and its specific calculation process is as shown in formula 6,

[0021] (6).

[0022] The specific calculation process of step S500 is: using the lag rate v c ( t ), the viscous increase time T n+, calculate the real-time rate during the viscous increase response stage of the gas concentration, i.e., the viscous increase rate. v n+ ( t ), and its specific calculation process is as shown in Formula 7.

[0023] (7).

[0024] The specific calculation process of step S600 is as follows: Utilize the lag time T c , lag rate v c ( t ), viscous increase time T n+ and viscous increase rate v n+ ( t ) to calculate the dynamic threshold for gas concentration regulation and warning during the production process of the coal mining face as shown in Formula 8.

[0025] (8).

[0026] In the formula, 1% is the power cut threshold for the gas concentration set for the coal mining face.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] For underground coal mining, the gas concentration monitoring sensor at the coal mining face is far from the working station where the gas concentration regulation activities are carried out. The control system composed of the gas concentration and its regulation activities is a typical time-lagged and aftereffect system.

[0029] Compared with the original power cut threshold of 1% for the gas concentration at the working face, the method for obtaining the dynamic threshold for gas concentration warning and regulation of the coal mining face provided by the present invention takes the time-lagged response variables and time variables of the gas concentration after the regulation activities are changed as the reference variables for the warning threshold, constructs a time-varying threshold that varies with different time-lagged effects of gas concentration regulation, can effectively cope with the time-lagged and aftereffect problems during the gas concentration regulation process of the coal mining face, and realizes the real-time and accurate evaluation and warning of the gas concentration at the coal mining face. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flowchart of the method for obtaining the dynamic threshold for gas concentration warning and regulation of the coal mining face according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following further explains the present invention in detail with reference to the accompanying drawings of the specification, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the protection scope of the present invention more clearly defined.

[0032] Refer to Figure 1 As shown, a method for obtaining the dynamic threshold of gas concentration early warning and regulation in a coal mining face. This method first monitors and records the gas concentration in the coal mining face every 20 minutes for 20 consecutive days, and then calculates the characteristic time points of the time-delay response of the gas concentration based on the continuously monitored data. On this basis, the delay time and viscous increase time of the time-delay response of the gas concentration are calculated, and the delay rate of the time-delay response of the gas concentration is calculated using the real-time state of the gas concentration during the production process. Then, the viscous increase rate of the time-delay response of the gas concentration is calculated using the delay rate and viscous increase time of the time-delay response of the gas concentration. Finally, the dynamic threshold of the gas concentration regulation early warning in the working face during the production process is calculated using the delay time, delay rate, viscous increase time, and viscous increase rate of the time-delay response of the gas concentration.

[0033] The specific process is as follows:

[0034] S100: Record the monitoring data of the gas concentration in the coal mining face every 20 minutes and continuously monitor and count for 20 days.

[0035] S200: Calculate the characteristic time points of the time-delay response of the gas concentration according to the continuously monitored data, including the initial moment of the time-delay response of the gas concentration, the end moment of the time-delay response, and the end moment of the viscous increase response stage.

[0036] Refer to Figure 1 As shown, the specific calculation method of each characteristic time point in this embodiment is as follows:

[0037] Let x ( t i ) be the gas concentration in the coal mining face at the moment t i in the statistical data. When t i satisfies Formula 1, i = 0, 1, 2, …, record t i = t 0 , which is the initial moment of the time-delay response of the gas concentration;

[0038] (1)

[0039] When t i satisfies Formula 2, record t i = t c , which is the end moment of the time-delay response of the gas concentration;

[0040] (2)

[0041] When t i satisfies Formula 3, record t i = t n+ , which is the end time of the viscous increase response stage of the gas concentration;

[0042] (3).

[0043] S300: Calculate the hysteresis time and viscous increase time of the gas concentration time-delay response by using the initial time of the gas concentration hysteresis response, the end time of the gas concentration hysteresis response, and the end time of the viscous increase response stage of the gas concentration.

[0044] Refer to Figure 1 As shown, the specific calculation method of the hysteresis time and viscous increase time of the gas concentration time-delay response in this embodiment is as follows:

[0045] The hysteresis time of the gas concentration time-delay response in the coal mining face T c As shown in Formula 4.

[0046] T c =t c - t 0 (4)

[0047] The viscous increase time of the gas concentration time-delay response in the coal mining face T n+ As shown in Formula 5.

[0048] T n+ = t n+ - t c (5)

[0049] Taking the gas concentration monitoring data of the coal mining face "A" in a certain underground coal mine as an example, according to the monitoring data of the characteristic time points of the gas concentration time-delay response, the hysteresis time T c = 60 min, and the viscous increase time T n+ = 90 min, of the gas concentration time-delay response of this working face are calculated.

[0050] S400: Calculate the real-time rate of the gas concentration hysteresis response, that is, the hysteresis rate, by using the real-time state of the gas concentration during the production process.

[0051] Refer to Figure 1 As shown, the specific calculation method for the real-time rate of the gas concentration hysteresis response in this embodiment is as follows:

[0052] Let x ( t j-2 )、 x ( t j-1 ) and x ( t j ) be the real-time states of the gas concentration during the production process at time t j-2 , time t j-1 and time t j respectively. Let j = 0, 1, 2, …, and use the real-time states of the gas concentration x ( t j-2 ), x ( t j-1 ) and x ( t j ) to calculate the real-time rate of the gas concentration hysteresis response, that is, the hysteresis rate v c ( t ). The specific calculation process is as shown in Formula 6.

[0053] (6)

[0054] Among the gas concentration monitoring data of the coal mining face "A", the actually monitored gas concentrations at three consecutive time points are respectively x ( t j-2 ) = 0.61%, x ( t j-1 ) = 0.65%, x ( t j ) = 0.72%. Then, the gas concentration hysteresis rate t j at time v c ( t ) of the coal mining face "A" is:

[0055]

[0056] S500: Calculate the real-time rate during the viscous increase response stage of the gas concentration, i.e., the viscous increase rate, using the hysteresis rate and viscous increase time of the time-delay response of the gas concentration.

[0057] Refer to Figure 1 As shown, the specific calculation method for the viscous increase rate of the time-delay response of the gas concentration in this embodiment is:

[0058] (7)

[0059] In the gas concentration monitoring data of the coal mining face "A", the viscous increase time of the time-delay response of the gas concentration T n+ = is 90 min, t j and the hysteresis rate of the gas concentration at the v c ( t ) = 0.00275% / min. Then, the viscous increase rate of the gas concentration of the coal mining face "A" at the t j moment is:

[0060] .

[0061] S600: Calculate the dynamic threshold for regulating and warning the gas concentration of the coal mining face during the production process using the hysteresis time, hysteresis rate, viscous increase time, and viscous increase rate of the time-delay response of the gas concentration.

[0062] Refer to Figure 1 As shown, the specific calculation method for the dynamic threshold of regulating and warning the gas concentration during the production process of the coal mining face in this embodiment is:

[0063] (8)

[0064] In the formula, 1% is the power-off threshold of the set gas concentration of the coal mining face.

[0065] In the gas concentration monitoring data of the coal mining face "A", using the already calculated hysteresis time T c = of 60 min, viscous increase time T n+ = of 90 min, and the hysteresis rate t j of the gas concentration of the coal mining face "A" at the v c ( t ) = 0.00275% / min and the viscous increase rate vn+ ( t ), the calculated t j The dynamic threshold for gas concentration regulation and early warning at the coal mining face "A" at the moment is:

[0066]

[0067] At the coal mining face "A" at t j the moment, the gas concentration is x ( t j ) = 0.72%. If the original fixed early warning threshold of 1% is used, no regulation is required. However, using the dynamic threshold calculation method of the present invention, the calculated t j dynamic threshold for gas concentration regulation and early warning at the moment is . Obviously, the gas concentration at this moment exceeds the threshold at this moment, and regulation measures should be taken immediately.

[0068] The gas concentration monitoring sensor at the coal mining face in underground coal mining is far from the working station where the regulation activities of the gas concentration are located. The control system composed of the gas concentration and its regulation activities is a typical time-delay and aftereffect system. Compared with the original power-off threshold of 1%, the dynamic threshold for gas concentration early warning and regulation provided by the present invention takes the time-delay response variable and time variable of the gas concentration after the regulation activities are changed as the reference variables of the early warning threshold, and constructs a time-varying threshold that varies with different time-delay and aftereffect effects of gas concentration regulation, which can effectively cope with the time-delay and aftereffect problems in the process of gas concentration regulation at the coal mining face and realize the real-time and accurate evaluation and early warning of the gas concentration at the coal mining face.

Claims

1. A method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face, characterized in that: It includes the following steps, S100: Continuously record the monitoring data of the gas concentration in the coal mining face at regular intervals; S200: Calculate the characteristic time points of the time-delay response of the gas concentration according to the continuously monitored data; S300: Calculate the delay time and viscous increase time of the time-delay response of the gas concentration according to the characteristic time points of the time-delay response of the gas concentration; S400: Calculate the real-time rate of the time-delay response of the gas concentration, that is, the delay rate, according to the real-time state of the gas concentration during the production process; S500: Calculate the real-time rate of the gas concentration in the viscous increase response stage, that is, the viscous increase rate, by using the delay rate and viscous increase time of the time-delay response of the gas concentration; S600: Calculate the dynamic threshold of the gas concentration regulation warning in the working face during the production process by using the delay time, delay rate, viscous increase time and viscous increase rate of the time-delay response of the gas concentration.

2. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 1, characterized in that: In the step S100, it is recorded every 30 minutes and continuously monitored and statistically analyzed for 20 days.

3. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 1, characterized in that: In the step S200, the characteristic time points of the time-delay response of the gas concentration in the coal mining face include the initial moment of the time-delay response of the gas concentration, the end moment of the time-delay response, and the end moment of the viscous increase response stage.

4. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 3, characterized in that: The specific calculation process of the step S200 is: S201: Set x ( t i ) as the gas concentration of the coal mining face at t i moment in the statistical data. When t i satisfies Formula 1, i = 0, 1, 2, …, denote t i = t 0 , which is the initial moment of the gas concentration hysteretic response; （1） S202: When t i satisfies Formula 2, record t i = t c , which is the end time of the hysteretic response of gas concentration; （2） S203: When t i satisfies Formula 3, record t i = t n+ , which is the end time of the viscous increase response stage of the gas concentration; （3）。 5. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 4, characterized in that: The specific calculation process of the step S300 is: S301: Hysteresis time of the time-delay response of the gas concentration in the coal mining face T c As shown in Formula 4 T c =t c - t 0 （4） S302: Viscous increase time of gas concentration time lag response in coal mining face T n+ As shown in Formula 5 T n+ = t n+ - t c （5）。 6. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 1 or 5, characterized in that: The specific calculation process of the step S400 is: Using the real-time concentration of gas during production x ( t j-2 ), x ( t j-1 )and x ( t j ), j = 0, 1, 2, …, calculate the real-time rate of the hysteresis response of the gas concentration, that is, the hysteresis rate v c ( t ), the specific calculation process is shown in Formula 6, （6）。 7. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 6, characterized in that: The specific calculation process of the step S500 is: Hysteresis rate using the time lag response of gas concentration v c ( t ) Viscous increase time T n+ , calculate the real-time rate in the viscous increase response stage of gas concentration, that is, the viscous increase rate v n+ ( t ), and its specific calculation process is shown in Equation 7 （7）。 8. The method for obtaining the dynamic threshold of gas concentration warning and regulation in a coal mining face according to claim 7, characterized in that: The specific calculation process of the step S600 is: The hysteresis time Tc , the hysteresis rate vc ( t ), the viscous increase time Tn+ and the viscous increase rate vn+ ( t ) are used to calculate the dynamic threshold for gas concentration regulation and warning during the production process of the coal mining face as shown in Equation 8. （8） In the formula, 1% is the power-off threshold of the set gas concentration in the coal mining face.

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