A mine methane concentration monitoring system and its monitoring method

Abstract

The present invention relates to the technical field of mine methane concentration monitoring, and in particular to a mine methane concentration monitoring system and its monitoring method, which includes an explosion-proof housing, a molecular sieve for absorbing excess H20 and S02 interference gases in underground air, an air inlet hole reflector, an optical gas chamber, a pyroelectric detector, and an infrared light source. The molecular sieve, the air inlet hole reflector, and the optical gas chamber are installed inside the explosion-proof housing. The molecular sieve is closely attached to the optical gas chamber through the air inlet hole reflector. A pyroelectric detector and an infrared light source are installed inside the optical gas chamber. In the present invention, the service life of the optical gas chamber is effectively extended, the interference of the underground environment on the optical system is reduced, the stable operation of the system in a harsh environment is ensured. At the same time, by adopting a calculation method for the replacement cycle of the filtering device based on an optimization model, the replacement time of the molecular sieve is accurately predicted, unnecessary maintenance is avoided, and the operation efficiency of the system and the accuracy of the detection data are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of mine methane concentration monitoring, and specifically to a mine methane concentration monitoring system and its monitoring method. Background Art

[0002] A mine methane concentration monitoring system is a device specifically designed to monitor the methane gas concentration in coal mines. It is crucial for preventing gas explosions and other related safety accidents;

[0003] Existing methane concentration monitoring systems in coal mines usually use traditional methane sensors for monitoring. However, these systems have low intelligence and are difficult to achieve linkage with other safety control systems. In addition, the optical system has high requirements for the working environment and may not work properly when directly placed underground. Therefore, a filtering device is needed to absorb interfering gases in the underground air, such as water vapor (H 2 O), sulfur dioxide (SO 2 ) etc., to ensure the long-term stable operation of the optical system;

[0004] Currently, the filtering device usually uses molecular sieve to absorb these interfering gases. If the replacement cycle of the molecular sieve cannot be accurately calculated, during the process of replacing the molecular sieve, if the replacement is too early, the replacement frequency will increase, and if the replacement is too late, the accuracy of the detection data will be affected. Therefore, a mine methane concentration monitoring system and its monitoring method are proposed for the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a mine methane concentration monitoring system and its monitoring method to solve the problem that the filtering device usually uses molecular sieve to absorb these interfering gases. If the replacement cycle of the molecular sieve cannot be accurately calculated, during the process of replacing the molecular sieve, if the replacement is too early, the replacement frequency will increase, and if the replacement is too late, the accuracy of the detection data will be affected.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A mine methane concentration monitoring system and its monitoring method, including an explosion-proof housing, used to absorb the excess H 2 0, SO 2Molecular sieve for interfering gas, intake hole reflector, optical gas chamber, pyroelectric detector and infrared light source. Inside the explosion-proof housing, there are a molecular sieve, an intake hole reflector and an optical gas chamber installed. The molecular sieve is in close contact with the optical gas chamber through the intake hole reflector. Inside the optical gas chamber, there are a pyroelectric detector and an infrared light source installed. The infrared light source is of the thermal radiation type. The pyroelectric detector is configured with two independent probes, and a filter film and a filter are respectively set with a size of 1.2 mm × 1.2 mm. The inside of the optical gas chamber is smooth, and there is an infrared light optical path inside the reflective gas chamber;

[0008] An electronic tag is provided on the molecular sieve, and a monitoring system is provided outside the molecular sieve. The monitoring system includes an information input module for model variable input, an optimization model algorithm module, a positioning module and a display module. The model variables include replacement cycle T, filtration equipment efficiency η(t), initial filtration efficiency η0, minimum filtration efficiency ηmin, filtration efficiency decay coefficient λ, maintenance cost C(T), average filtration efficiency e(T), and objective function f(T). According to the filtration equipment efficiency η(t), initial filtration efficiency η0, minimum filtration efficiency ηmin, filtration efficiency decay coefficient λ, maintenance cost C(T), and average filtration efficiency e(T) information input by the information input module, an optimization model for calculating the replacement cycle of the molecular sieve at the corresponding position is constructed. The expression of the filtration efficiency of the molecular sieve at time t is:

[0009] η(t) = η0·e -t

[0010] The expression of the optimization model for the replacement cycle of the molecular sieve at the corresponding position is:

[0011]

[0012] In the formula: is the objective function of the optimization model for the replacement cycle of the molecular sieve at the corresponding position; s.t.{ are the constraint conditions of the optimization model, T min and T max are respectively the minimum and maximum values of the working temperature of the gas chamber, and Hmin and Hmax are respectively the minimum and maximum values of the relative humidity of the gas chamber.

[0013] As a further optimized content of the present invention, wherein: the molecular sieve adopts a detachable design and is convenient to replace through the side interface of the explosion-proof housing.

[0014] As a further optimized content of the present invention, wherein: the wavelength selection of the filter film and the filter provided inside the pyroelectric detector matches the absorption peak of methane, and the wavelength range of the light wave emitted by the infrared light source includes the characteristic absorption wavelength of methane, 3.31 μm.

[0015] As a further optimized content of the present invention, wherein: the infrared light source has a function of automatically adjusting the light intensity, and dynamically adjusts the infrared light intensity according to the actual environmental conditions in the gas chamber.

[0016] As a further optimized content of the present invention, wherein: the positioning module of the monitoring system adopts a wireless sensor network to achieve real-time positioning and data transmission of multiple monitoring points in the mine.

[0017] As a further optimized content of the present invention, wherein: the model variables further include environmental temperature, humidity and air pressure, and the optimization model algorithm module can dynamically adjust the replacement cycle of the molecular sieve according to these variables.

[0018] As a further optimized content of the present invention, wherein: the information input module for the input of the model variables supports an automatic data acquisition function and can directly obtain real-time environmental data from the sensor network.

[0019] As a further optimized content of the present invention, wherein: the optical gas chamber adopts an anti-reflection coating design.

[0020] As a further optimized content of the present invention, wherein: the display module is equipped with a visualization interface, which can real-time display the methane concentration in the gas chamber, the working state of the equipment and the remaining life of the molecular sieve, and provide warning and alarm functions.

[0021] As a further optimized content of the present invention, wherein: S1: Data acquisition: Obtain the optical signal of the methane concentration in the optical gas chamber through a pyroelectric detector and an infrared light source;

[0022] S11: Setting and data collection: Set the irradiance I of the initial light 0 , the length L of the gas chamber, and the wavelength λ, and collect the data of the effective length L of the gas chamber and the absorption coefficient a(v) on the v wave;

[0023] S12: Methane concentration calculation: S121: Calculation of the light intensity after passing through the gas chamber:

[0024] ∑I t (v)=∫I 0 (v)exp[-a(v)cL]dv

[0025] S122: Calculation of the concentration of the gas to be measured:

[0026]

[0027] In the formula: I 0 (v) is the light intensity distribution information obtained by directly irradiating the interference system with the laser without passing through the gas chamber, and I t (v) is the light intensity distribution information of the laser after passing through the gas chamber and then passing through the interference system;

[0028] S2: Signal processing: The molecular sieve in the filtering device is used to absorb interfering gases to ensure the normal operation of the optical system, and the signal processing module amplifies and filters the optical signal;

[0029] S3: Optimization model: The monitoring system collects the working status information of the molecular sieve through the model variable input module, calculates the replacement cycle of the molecular sieve at different positions based on the optimization algorithm, and gives an alarm reminder.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. In the present invention, the service life of the optical gas chamber is effectively extended, the interference of the underground environment on the optical system is reduced, the stable operation of the system in harsh environments is ensured. At the same time, by adopting the calculation method of the replacement cycle of the filtering device based on the optimization model, the replacement time of the molecular sieve is accurately predicted, unnecessary maintenance is avoided, the operation efficiency of the system and the accuracy of the detection data are improved. At the same time, the system design has high scalability and intelligence, can be linked with other coal mine safety monitoring systems, and provides an effective guarantee for the safe production of the mine;

[0032] 2. In the present invention, by setting core components such as an explosion-proof housing, an optical gas chamber and a pyroelectric detector, the normal operation of the system in the complex environment of the coal mine is ensured. By monitoring and optimizing the filtering device, the effective working time of the system is greatly extended. And through the set electronic tag, the replacement time of the molecular sieve inside the methane concentration monitoring system installed at different positions can be calculated more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 is a flowchart of a mine methane concentration monitoring system and its monitoring method of the present invention.

[0035] In the figure: 1. Explosion-proof housing; 2. Molecular sieve; 3. Inlet hole reflector; 4. Optical gas chamber; 5. Pyroelectric detector; 6. Infrared light source. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] Please refer to Figure 1-2 , the present invention provides a technical solution:

[0037] A mine methane concentration monitoring system and its monitoring method, including an explosion-proof housing 1, used to absorb the excess H in the underground air 2 0, SO 2Molecular sieve 2 for interfering gas, intake hole reflector 3, optical gas chamber 4, pyroelectric detector 5 and infrared light source 6. Inside the explosion-proof housing 1, there are installed molecular sieve 2, intake hole reflector 3 and optical gas chamber 4. Molecular sieve 2 is in close contact with optical gas chamber 4 through intake hole reflector 3. Inside optical gas chamber 4, there are installed pyroelectric detector 5 and infrared light source 6. Infrared light source 6 is of the thermal radiation type. Pyroelectric detector 5 is configured with two independent probes, and filter plates and optical filters with a size of 1.2 mm × 1.2 mm are respectively set. The inside of optical gas chamber 4 is smooth, and an infrared light optical path is provided inside the reflective gas chamber 4;

[0038] An electronic tag is provided on molecular sieve 2, and a monitoring system is provided outside molecular sieve 2. The monitoring system includes an information input module for inputting model variables, an optimization model algorithm module, a positioning module and a display module. The model variables include replacement period T, filtration equipment efficiency η(t), initial filtration efficiency η0, minimum filtration efficiency ηmin, filtration efficiency decay coefficient λ, maintenance cost C(T), average filtration efficiency e(T), and objective function f(T). According to the information of filtration equipment efficiency η(t), initial filtration efficiency η0, minimum filtration efficiency ηmin, filtration efficiency decay coefficient λ, maintenance cost C(T), and average filtration efficiency e(T) input by the information input module, an optimization model for calculating the replacement period of molecular sieve 2 at the corresponding position is constructed. The expression of the filtration efficiency of the molecular sieve at time t is:

[0039] η(t) = η0·e -t

[0040] The expression of the optimization model for the replacement period of molecular sieve 2 at the corresponding position is:

[0041]

[0042] In the formula: is the objective function of the optimization model for the replacement period of molecular sieve 2 at the corresponding position; s.t.{ are the constraint conditions of the optimization model, T min and T max are respectively the minimum and maximum values of the working temperature of the gas chamber, and Hmin and Hmax are respectively the minimum and maximum values of the relative humidity of the gas chamber.

[0043] As a further technical solution of this scheme, molecular sieve 2 adopts a detachable design and is convenient to replace through the side interface of explosion-proof housing 1. Through the above settings, the safety and convenience of the equipment during maintenance are ensured;

[0044] As a further technical solution of this scheme, the wavelength selection of the filter plate and optical filter set inside pyroelectric detector 5 matches the absorption peak of methane. The wavelength range of the light wave emitted by infrared light source 6 includes the characteristic absorption wavelength of methane, 3.31 μm. Through the above settings, the detection accuracy of the methane concentration of the system is improved;

[0045] As a further technical solution for the implementation of this solution, the infrared light source 6 has the function of automatically adjusting the light intensity, dynamically adjusts the infrared light intensity according to the actual environmental conditions in the gas chamber 4, and optimizes the detection signal through the above settings;

[0046] As a further technical solution for the implementation of this solution, the positioning module of the monitoring system uses a wireless sensor network to achieve real-time positioning and data transmission of multiple monitoring points in the mine, so as to independently manage and optimize the molecular sieves (2) at different positions;

[0047] As a further technical solution for the implementation of this solution, the model variables also include environmental temperature, humidity and air pressure. The optimization model algorithm module can dynamically adjust the replacement cycle of the molecular sieve 2 according to these variables. Through the above settings, it can cope with the changes in the environmental conditions in the mine;

[0048] As a further technical solution for the implementation of this solution, the information input module for the input of model variables supports the automatic data collection function, can directly obtain real-time environmental data from the sensor network, reduces manual intervention and improves the real-time response ability of the system;

[0049] As a further technical solution for the implementation of this solution, the optical gas chamber 4 adopts an anti-reflection coating design to reduce optical interference and reflection loss, and improve the detection sensitivity and accuracy of the system;

[0050] As a further technical solution for the implementation of this solution, the display module is equipped with a visual interface, which can real-time display the methane concentration in the gas chamber, the working state of the equipment and the remaining life of the molecular sieve 2, and provide warning and alarm functions. Through the above settings, it can ensure that the operator can timely know the operation situation of the equipment;

[0051] As a further technical solution for the implementation of this solution, S1: Data collection: Obtain the optical signal of the methane concentration in the optical gas chamber 4 through the pyroelectric detector 5 and the infrared light source 6;

[0052] S11: Setting and data collection: Set the irradiance I 0 of the initial light, the length L of the gas chamber, and the wavelength λ, and collect the data of the effective length L of the gas chamber and the absorption coefficient a(v) on the v wave;

[0053] S12: Methane concentration calculation: S121: Calculation of the light intensity after passing through the gas chamber:

[0054] ΣI t (v) = ∫I 0 (v)exp[-a(v)cL]dv

[0055] S122: Calculation of the concentration of the gas to be measured:

[0056]

[0057] Where: I 0 (v) is the light intensity distribution information obtained by directly irradiating the interference system with the laser without passing through the gas chamber, and I t (v) is the light intensity distribution information of the laser passing through the gas chamber and then passing through the interference system;

[0058] S2: Signal processing: The molecular sieve 2 in the filtering device is used to absorb interfering gases to ensure the normal operation of the optical system, and the signal processing module amplifies and filters the optical signal;

[0059] S3: Optimization model: The monitoring system collects the working state information of the molecular sieve 2 through the model variable input module, calculates the replacement cycle of the molecular sieve 2 at different positions based on the optimization algorithm, and gives an alarm reminder.

[0060] In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above examples is only used to help understand the method of the present invention and its core idea. The above is only the preferred implementation manner of the present invention. It should be noted that due to the limited nature of written expression and objectively infinite specific structures, for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, should all be regarded as the protection scope of the present invention.

Claims

1. A mine methane concentration monitoring system, comprising an explosion-proof housing (1), a molecular sieve (2) for absorbing excess H2O and SO2 interfering gases in underground air, an air inlet reflector (3), an optical air chamber (4), a pyroelectric detector (5) and an infrared light source (6), characterized in that: The explosion-proof housing (1) is internally installed with a molecular sieve (2), an air inlet reflector (3) and an optical air chamber (4); the molecular sieve (2) is closely attached to the optical air chamber (4) via the air inlet reflector (3); a pyroelectric detector (5) and an infrared light source (6) are internally installed in the optical air chamber (4); the infrared light source (6) is of a thermal radiation type; the pyroelectric detector (5) is configured with two independent probes, each of which is provided with a 1.2 mm×1.2 mm filter and a filter; the interior of the optical air chamber (4) is smooth, and an infrared light path is provided inside the reflector air chamber (4); The molecular sieve (2) is provided with an electronic tag, and a monitoring system is provided outside the molecular sieve (2), wherein the monitoring system comprises an information input module for inputting model variables, an optimization model algorithm module, a positioning module and a display module, wherein the model variables comprise a replacement cycle T, a filter device efficiency η(t), an initial filter efficiency η0, a minimum filter efficiency ηmin, a filter efficiency attenuation coefficient λ, a maintenance cost C(T), an average filter efficiency e(T), and an objective function f(T). Based on the filter device efficiency η(t), the initial filter efficiency η0, the minimum filter efficiency ηmin, the filter efficiency attenuation coefficient λ, the maintenance cost C(T), and the average filter efficiency e(T) information inputted by the information input module, an optimization model for calculating the optimization of the replacement cycle of the molecular sieve (2) at the corresponding position is constructed, wherein the filter efficiency expression of the molecular sieve at time t is: η(t)=η0·e -t The expression of the optimization model for the replacement cycle optimization of the corresponding molecular sieve (2) is: Where: The objective function of the optimization model for optimizing the replacement cycle of the molecular sieve (2) at the corresponding position; To find the constraints of the optimization model, Tmin and Tmax are the minimum and maximum values ​​of the air chamber working temperature, Hmin and Hmax are the minimum and maximum values ​​of the air chamber relative humidity, respectively. The monitoring method of the mining methane concentration monitoring system comprises the following steps: S1: Data acquisition: obtaining the optical signal of methane concentration in the optical gas chamber (4) through the pyroelectric detector (5) and the infrared light source (6); S11: Setting and data collection: Setting the radiance I0 of the initial light, the length L of the air chamber, and the wavelength λ, and collecting data on the effective length L of the air chamber and the absorption coefficient a(v) on the v wave; S12: Calculation of methane concentration: S121: Calculation of light intensity after passing through the gas chamber: ∑I t (v)=∫I0(v)exp[-a(v)cL]|dv S122: Calculation of gas concentration to be measured: Where: I0(v) is the light intensity distribution information obtained by directly irradiating the interference system without passing through the gas chamber, I t (v) is the light intensity distribution information after the laser passes through the gas chamber and then through the interference system; S2: signal processing: using the molecular sieve (2) in the filter device to absorb the interfering gas to ensure the normal operation of the optical system, the signal processing module amplifies and filters the optical signal; S3: Optimizing the model: The monitoring system collects the working status information of the molecular sieve (2) through the model variable input module, calculates the replacement cycle of the molecular sieve (2) at different positions based on the optimization algorithm, and issues an alarm.

2. A mining methane concentration monitoring system according to claim 1, characterized in that: The molecular sieve (2) is designed to be detachable and can be easily replaced through the side interface of the explosion-proof housing (1).

3. A mining methane concentration monitoring system according to claim 1, characterized in that: The wavelengths of the filter and the optical filter arranged inside the pyroelectric detector (5) are selected to match the absorption peak of methane, and the wavelength range of the light waves emitted by the infrared light source (6) includes the characteristic absorption wavelength of methane, 3.31 μm.

4. A mining methane concentration monitoring system according to claim 1, characterized in that: The infrared light source (6) has the function of automatically adjusting the light intensity, and dynamically adjusts the infrared light intensity according to the actual environmental conditions in the air chamber (4).

5. A mining methane concentration monitoring system according to claim 1, characterized in that: The positioning module of the monitoring system adopts a wireless sensor network to achieve real-time positioning and data transmission of multiple monitoring points in the mine.

6. A mining methane concentration monitoring system according to claim 1, characterized in that: The model variables also include ambient temperature, humidity and air pressure, and the optimization model algorithm module can dynamically adjust the replacement cycle of the molecular sieve (2) according to these variables.

7. A mining methane concentration monitoring system according to claim 1, characterized in that: The information entry module for the model variable input supports an automatic data collection function and can directly obtain real-time environmental data from the sensor network.

8. A mining methane concentration monitoring system according to claim 1, characterized in that: The optical air chamber (4) is designed with an anti-reflection coating.

9. A mining methane concentration monitoring system according to claim 1, characterized in that: The display module is equipped with a visual interface, which can display the methane concentration in the gas chamber, the working status of the equipment and the remaining life of the molecular sieve (2) in real time, and provide early warning and alarm functions.

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