A goaf oxygen concentration monitoring method, system and device

Abstract

The application relates to the technical field of oxygen concentration monitoring, in particular to a goaf oxygen concentration monitoring method, system and equipment, which comprises the following steps: presetting measuring points at different positions of a ventilation side of a goaf, collecting oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measuring point in real time; obtaining oxygen concentration abnormal values, residual coal oxidation change rates and oxygen concentration retention coefficients of each measuring point at each moment, and screening to obtain reliable oxygen concentration data at each moment; simulating oxygen concentration simulation distribution diagrams of the goaf at each moment and each moment before the moment, obtaining simulation difference degrees of the reliable oxygen concentration data, extracting oxygen concentration simulation values from the oxygen concentration simulation distribution diagrams, and using the oxygen concentration simulation values and the reliable oxygen concentration data together for spontaneous combustion three-zone division of the ventilation side. The application aims to improve the quantity and accuracy of oxygen concentration data used for spontaneous combustion three-zone division, so as to improve the precision of spontaneous combustion three-zone division.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oxygen concentration monitoring, in particular to a goaf oxygen concentration monitoring method, system and equipment. BACKGROUND

[0002] The goaf is a hollow area left after coal mining. Due to roof collapse and rock movement, the internal environment is complex and changeable. The residual float coal in the goaf is prone to low-temperature oxidation under the condition of air leakage and oxygen supply. If the heat is not dissipated, it will lead to spontaneous combustion, which is one of the major disasters in coal mine safety production. Goaf coal spontaneous combustion is the coupling effect of air seepage, oxygen transport and heat transfer. Intelligent monitoring of the oxygen concentration field distribution in the goaf is the basis for the division of the "three zones" of spontaneous combustion and fire prevention and extinguishing engineering.

[0003] At present, the oxygen concentration monitoring in the goaf generally uses beam tube monitoring technology. By regularly extracting gas samples from the goaf, the measured oxygen concentration data of the measuring points in the goaf can be obtained. However, due to the fast advancing speed of the fully mechanized working face, the sampling distance of the adjacent goaf gas sampling monitoring at the same measuring point is large, and the measured oxygen concentration data is greatly different.

[0004] The prior art needs to obtain more oxygen concentration data by interpolation or fitting method, and then realize the division of the "three zones" of spontaneous combustion in the goaf based on the critical oxygen concentration method. However, due to the influence of factors such as dust, coal slurry flooding and pipeline gas leakage, the accuracy of the measured oxygen concentration data is difficult to identify, the error of the interpolation or fitting method is increased, and the precision of the "three zones" division in the goaf is reduced, so that it is difficult to accurately judge the actual influence of the fire prevention and extinguishing scheme on the oxygen concentration in the goaf, which is not conducive to timely optimization and adjustment. SUMMARY

[0005] In view of the above, it is necessary to provide a goaf oxygen concentration monitoring method, system and equipment. Compared with the traditional goaf oxygen concentration monitoring method, the number and accuracy of the oxygen concentration data used for the division of the three zones of spontaneous combustion are improved, so as to improve the precision of the division of the three zones of spontaneous combustion:

[0006] In the first aspect, the embodiments of the present application provide a goaf oxygen concentration monitoring method, which comprises the following steps:

[0007] Pre-set measuring points at different positions of the ventilation side of the goaf, and real-time collection of oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measuring point;

[0008] By comparing the oxygen concentration data of each measuring point at each time with that at the adjacent time, and comparing the oxygen concentration data of all measuring points at each time, the oxygen concentration abnormal value of each measuring point at each time is obtained; by the change of the carbon monoxide concentration data and the carbon dioxide concentration data of each measuring point at each time and before each time, and the correlation between the carbon monoxide concentration data, the carbon dioxide concentration data and the oxygen concentration data of each measuring point at each time and before each time, the residual coal oxidation change rate of each measuring point at each time is obtained, and combined with the oxygen concentration abnormal value, the oxygen concentration retention coefficient of each measuring point at each time is obtained, and then the reliable oxygen concentration data of each time is screened from the oxygen concentration data of all measuring points at each time and before each time;

[0009] By the actual size of the working face, the goaf, the air inlet roadway and the air return roadway at each time and before each time, the oxygen concentration simulation distribution diagram of the goaf at each time is simulated, and the simulation oxygen concentration data of the reliable oxygen concentration data is obtained from the position of each measuring point for comparison, to obtain the simulation difference degree of the reliable oxygen concentration data, so as to extract the oxygen concentration simulation value from the oxygen concentration simulation distribution diagram, and the reliable oxygen concentration data is used together for the spontaneous combustion three-zone division of the ventilation side.

[0010] In one of the embodiments, the oxygen concentration abnormal value is obtained by:

[0011] The difference value of the oxygen concentration data of each measuring point at each time and the adjacent previous time is calculated.

[0012] The number of measuring points is 2, and the difference amount of the oxygen concentration data of each measuring point and another measuring point at each time is calculated.

[0013] The oxygen concentration abnormal value is the normalized value of the product of the positive proportional mapping result of the difference value and the difference amount.

[0014] In one of the embodiments, the residual coal oxidation change rate is obtained by:

[0015] The distance from each measuring point to the working face is obtained in real time, which is recorded as the depth of each goaf.

[0016] The correlation between the carbon monoxide concentration data, the carbon dioxide concentration data and the oxygen concentration data of each measuring point at each time and before each time is recorded as the first correlation and the second correlation, respectively.

[0017] The fitting curve functions of the carbon monoxide concentration data and the carbon dioxide concentration data of each measuring point at each time and before each time are recorded as the first fitting curve function and the second fitting curve function, respectively, wherein the abscissa is the depth of the goaf; the derivative values of the first fitting curve function and the second fitting curve function at the depth of the goaf of each measuring point at each time are recorded as the first derivative value and the second derivative value, respectively.

[0018] The oxidation change rate of the residual coal is obtained by the first correlation degree, the first derivative value, the second correlation degree and the second derivative value.

[0019] In one embodiment, the method for obtaining the oxidation change rate of the residual coal comprises:

[0020] The product of the first correlation degree and the absolute value of the first derivative value is denoted as a first product;

[0021] The product of the second correlation degree and the absolute value of the second derivative value is denoted as a second product;

[0022] The oxidation change rate of the residual coal is the sum of the first product and the second product.

[0023] In one embodiment, the method for obtaining the oxygen concentration retention coefficient comprises:

[0024] The reciprocal of the sum of the oxygen concentration abnormal value and a preset positive number is calculated, and the reciprocal is mapped to a value greater than 1;

[0025] The mapped value is used as the base of an exponential function with the oxidation change rate of the residual coal as the index, and the oxygen concentration retention coefficient is the calculation result of the exponential function.

[0026] In one embodiment, the method for obtaining the reliable oxygen concentration data comprises:

[0027] The oxygen concentration data corresponding to the oxygen concentration retention coefficient greater than a preset retention threshold in the normalization result are used as the reliable oxygen concentration data.

[0028] In one embodiment, the method for obtaining the simulation difference degree comprises:

[0029] The deviation value between the reliable oxygen concentration data and the simulation oxygen concentration data thereof is calculated, and the simulation difference degree is the ratio of the deviation value to the reliable oxygen concentration data.

[0030] In one embodiment, the simulation oxygen concentration value extracted from the oxygen concentration simulation distribution map and the reliable oxygen concentration data are used together for the spontaneous combustion three-zone division of the ventilation side, which comprises:

[0031] The simulation oxygen concentration data corresponding to the reliable oxygen concentration data less than or equal to a preset difference threshold are selected, and the oxygen concentration simulation values at the adjacent positions of the selected results in the oxygen concentration simulation distribution map and the goaf depth are extracted;

[0032] An oxygen concentration monitoring curve is constructed according to the extraction results and the reliable oxygen concentration data, and is used for the spontaneous combustion three-zone division of the ventilation side.

[0033] In a second aspect, the embodiments of the present application further provide a goaf oxygen concentration monitoring system, which comprises:

[0034] a concentration monitoring module, configured to collect oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measuring point in real time at preset measuring points at different positions of the ventilation side of the goaf;

[0035] a concentration analysis module, configured to obtain oxygen concentration outliers of each measuring point at each time point by comparing the oxygen concentration data of each measuring point at each time point with the oxygen concentration data of the measuring point at the adjacent time point, and comparing the oxygen concentration data of all measuring points at each time point; obtain the oxygen oxidation change rate of each measuring point at each time point by the change of the carbon monoxide concentration data and the carbon dioxide concentration data of each measuring point at each time point and before each time point, and the correlation between the carbon monoxide concentration data, the carbon dioxide concentration data and the oxygen concentration data of each measuring point at each time point and before each time point; obtain the oxygen concentration retention coefficient of each measuring point at each time point in combination with the oxygen concentration outliers; and further screen reliable oxygen concentration data of each time point from the oxygen concentration data of all measuring points at each time point and before each time point;

[0036] a spontaneous combustion three-zone division module, configured to simulate an oxygen concentration simulation distribution map of the goaf at each time point by the actual size of the working face, the goaf, the air inlet roadway and the air return roadway at each time point and before each time point, and obtain simulated oxygen concentration data of the reliable oxygen concentration data by comparing the position of each measuring point, to obtain the simulation difference of the reliable oxygen concentration data, so as to extract oxygen concentration simulation values from the oxygen concentration simulation distribution map, and use the oxygen concentration simulation values and the reliable oxygen concentration data to divide the spontaneous combustion three-zone of the ventilation side.

[0037] In a third aspect, the embodiments of the present application further provide a goaf oxygen concentration monitoring device, which comprises a memory, a processor and a computer program stored in the memory and running on the processor, and the processor implements the steps of the goaf oxygen concentration monitoring method of any one of the above aspects when executing the computer program.

[0038] The present application has at least the following beneficial effects:

[0039] The application can effectively detect abnormal conditions in the goaf oxygen concentration monitoring data by calculating the oxygen concentration abnormal value, which helps to improve the accuracy of subsequent spontaneous combustion three-zone division; by calculating the residual coal oxidation change rate, the intensity change of the residual coal oxidation reaction in the goaf can be measured, which helps to identify the area close to the spontaneous combustion "three-zone" boundary with intense oxidation reaction, and at the same time, combined with the oxygen concentration abnormal value, the reliability of each oxygen concentration data for spontaneous combustion "three-zone" division is quantified, the high-value oxygen concentration monitoring data is retained, and the influence of factors such as dust, coal slurry flooding and pipeline gas leakage is avoided, so as to ensure the accuracy of spontaneous combustion "three-zone" division;

[0040] Further, combined with numerical simulation and field monitoring data, the field monitoring data is supplemented, the data quantity for spontaneous combustion "three-zone" division is increased, and the spontaneous combustion "three-zone" division can be more accurately realized, so as to provide more accurate decision basis for fire prevention engineering. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 A step flow chart of a goaf oxygen concentration monitoring method provided by an embodiment of the application is shown in the figure;

[0043] Figure 2 A goaf gas concentration beam tube monitoring schematic diagram is shown in the figure;

[0044] Figure 3 A reliable oxygen concentration data screening process schematic diagram is shown in the figure;

[0045] Figure 4 An inert coupling gas fire prevention and extinguishing equipment system schematic diagram is shown in the figure. DETAILED DESCRIPTION

[0046] In the description of the embodiments of the application, the words "exemplary", "or", "for example" are used to represent an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of the application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words "exemplary", "or", "for example" are intended to present the relevant concept in a specific manner.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. It will be understood that unless otherwise specified, "or" as used herein is inclusive or meant to be the same as "and / or." It will be further understood that the use of relational terms, if any, such as first, second, third, and the like, are used solely to distinguish one from another entity or action without necessarily implying a sequence or order to such entities or actions.

[0048] In addition, it should be pointed out that the terms "first", "second" in the present application are used to distinguish similar objects, and are not used to describe a specific sequence or order.

[0049] The specific scheme of the goaf oxygen concentration monitoring method, system and device provided by the present application will be specifically described below in combination with the drawings.

[0050] Please refer to Figure 1 , which shows the step flow chart of a goaf oxygen concentration monitoring method provided by an embodiment of the present application, and the method comprises the following steps:

[0051] Step 1, presetting beam tube measuring points at different positions of the ventilation side of the goaf, and collecting oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each beam tube measuring point in real time.

[0052] Affected by the blocking of the hydraulic support canopy beam, the present application is provided with a set of goaf gas sampling monitoring system in the air inlet roadway and the air return roadway of the working face, and the goaf gas sampling monitoring system comprises a beam tube measuring point, a beam tube and a ZQC6 / 6 underground beam tube gas sampling device. The goaf gas concentration beam tube monitoring schematic diagram is shown in Figure 2 , Figure 2 1 is a working face, the working face is pushed in the direction from right to left, 2 is a goaf, 3 is a support, 4 is an air inlet roadway, 5 is an air return roadway, 6 is a steel sleeve with a built-in beam tube, 71 is an air inlet side beam tube measuring point, 72 is an air return side beam tube measuring point, 8 is a ZQC6 / 6 underground beam tube gas sampling device. Among them, the air inlet side beam tube measuring point and the air return side beam tube measuring point are both two, the air inlet side beam tube measuring point 71 comprises a beam tube measuring point 711 and a beam tube measuring point 712, the air return side beam tube measuring point 72 comprises a beam tube measuring point 721 and a beam tube measuring point 722, the air inlet side and the air return side are collectively referred to as the ventilation side, and the air inlet side beam tube measuring point and the air return side beam tube measuring point are collectively referred to as the ventilation side beam tube measuring point.

[0053] The beam tube measuring point 711 and the beam tube measuring point 712 respectively extend 5m and 6m into the goaf, and the beam tube measuring point 721 and the beam tube measuring point 722 also respectively extend 5m and 6m into the goaf, and the height of each beam tube measuring point from the floor is 0.1m. In order to protect the beam tube from being damaged by the falling gangue, the beam tube is placed in a steel casing. Among them, 5m and 6m are only one embodiment of the present application, and the implementer can set its specific value according to the actual situation under the condition of ensuring that the distance between the beam tube measuring point 711 and the beam tube measuring point 712 is close, and the distance between the beam tube measuring point 721 and the beam tube measuring point 722 is close; 0.1m is only one embodiment of the present application, and the implementer can set its specific value according to the actual situation.

[0054] With the advancing of the working face, the ZQC6 / 6 underground beam tube gas sampling device is used, and sampling is taken at each beam tube measuring point every 12h to monitor the gas concentration data of each beam tube measuring point at each time, including oxygen concentration data, carbon monoxide concentration data, and carbon dioxide concentration data. At the same time, the distance of each beam tube measuring point from the working face at each time is recorded, which is recorded as the goaf depth of each beam tube measuring point at each time. Among them, 12h is only one embodiment of the present application, and the implementer can set its specific value according to the actual situation, and the present application does not make special limitations.

[0055] Step 2, obtaining the oxygen concentration abnormal value of each beam tube measuring point at each time and the residual coal oxidation rate of each beam tube measuring point, and then obtaining the oxygen concentration retention coefficient of each beam tube measuring point at each time, and screening each reliable oxygen concentration data of each time from the oxygen concentration data of all beam tube measuring points at each time and before each time.

[0056] Step 2.1, by comparing the oxygen concentration data of each beam tube measuring point at each time and the adjacent time, and comparing the oxygen concentration data of all beam tube measuring points at each time, the oxygen concentration abnormal value of each beam tube measuring point at each time is obtained.

[0057] With the advancing of the working face, the distance of the beam tube measuring point from the working face increases. Since the maximum depth of the beam tube measuring point into the goaf at the initial time is 6m, the beam tube measuring point is located in the goaf area close to the working face at this time, the roof falling rock mass is loose and accumulated, the porosity between the broken rock masses is large, and the initial oxygen concentration is relatively high. With the continuous advancing of the working face and the increase of the goaf depth, the compaction degree of the falling and broken rock mass in the goaf is greater, the porosity of the coal and rock mass gradually decreases, and the oxygen concentration in the goaf gradually decreases. Therefore, with the increase of the distance of the beam tube measuring point from the working face, the oxygen concentration value should gradually decrease until it is almost close to 0.

[0058] The application utilizes the beam tube measuring point 711 and the beam tube measuring point 712 which are close to each other to monitor the oxygen concentration of the air inlet side goaf, and the oxygen concentration distribution of the beam tube measuring point 711 and the beam tube measuring point 712 should be similar, and the beam tube measuring point 711 and the beam tube measuring point 712 are equivalent measuring points. The beam tube measuring point 721 and the beam tube measuring point 722 are also equivalent measuring points.

[0059] Since the beam tube is easily compacted by the falling gangue in the goaf, and the coal slurry formed after the water source such as working face production water and roof water enters the goaf also easily blocks the beam tube measuring point, thus leading to the measured oxygen concentration result being smaller. Taking the tth moment as an example, by comparing the oxygen concentration data of any beam tube measuring point at the tth moment and the adjacent moment, and comparing the oxygen concentration data of the any beam tube measuring point and its equivalent measuring point at the tth moment, the oxygen concentration abnormal value of the any beam tube measuring point at the tth moment is obtained, specifically as follows:

[0060] calculating the difference value of the oxygen concentration data of the any beam tube measuring point at the tth moment and the adjacent previous moment;

[0061] calculating the difference amount of the oxygen concentration data of the any beam tube measuring point and its equivalent measuring point at the tth moment;

[0062] The oxygen concentration abnormal value is the normalized value of the product of the positive proportional mapping result of the difference value and the difference amount.

[0063] It should be noted that the effect of positively proportional mapping of the difference value is to amplify the difference value when the oxygen concentration data at the tth moment does not conform to the oxygen concentration decreasing feature. When calculating the oxygen concentration abnormal value of the any beam tube measuring point at the 1th moment, the oxygen concentration abnormal value is the difference amount at the 1th moment.

[0064] In this embodiment, the expression of the oxygen concentration abnormal value of the any beam tube measuring point at the tth moment is as follows:

[0065] ; in the formula, indicates the oxygen concentration abnormal value of the any beam tube measuring point at the tth moment; exp( ) indicates an exponential function with a natural constant as the base number; , respectively indicate the oxygen concentration data of the any beam tube measuring point at the tth moment and the t-1th moment; indicates an absolute value operation; indicates the oxygen concentration data of the equivalent measuring point of the any beam tube measuring point at the tth moment; norm( ) indicates a normalization function.

[0066] In this embodiment, the normalization function is a Min-Max normalization method, which is a known technology, and the application will not be described again.

[0067] Need to explain: based on the downhole beam tube monitoring characteristics, when the oxygen concentration distribution does not meet the decreasing characteristics, it is very likely that the oxygen concentration data Abnormal phenomenon occurs in gas sampling monitoring process, resulting in oxygen concentration data Less than oxygen concentration data The greater; Reflects the oxygen concentration deviation of two equivalent measuring points at the same time, The greater, the greater the monitoring deviation of oxygen concentration data, the higher the abnormal degree, and the greater the oxygen concentration abnormal value The greater.

[0068] Step 2.2, through the change of carbon monoxide concentration data, carbon dioxide concentration data of each beam tube measuring point at each time and before each time, and the correlation between carbon monoxide concentration data, carbon dioxide concentration data and oxygen concentration data of each beam tube measuring point at each time and before each time, get the change rate of residual coal oxidation of each beam tube measuring point at each time.

[0069] Further, the beam tube monitoring in the goaf mainly uses the critical oxygen concentration method to divide the “three zones” of spontaneous combustion. In the oxidation spontaneous combustion zone, oxygen and residual coal are easy to have residual coal oxidation reaction. Oxygen is the raw material of residual coal oxidation reaction, and carbon monoxide and carbon dioxide concentration is the product of residual coal oxidation reaction. The more intense the residual coal oxidation reaction, the more oxygen is consumed, and the greater the increase of carbon monoxide and carbon dioxide concentration.

[0070] Because the heat generated by residual coal oxidation continues to accumulate in the oxidation spontaneous combustion zone, the local temperature of residual coal in the goaf rises sharply, and the risk of spontaneous combustion is high. In order to prevent spontaneous combustion of residual coal in the goaf and provide decision basis for working face advancing speed and goaf fire prevention and extinguishing, more attention should be paid to the gas concentration data reflecting the degree of residual coal oxidation reaction. These gas concentration data are most likely to be near the boundary of the “three zones” of spontaneous combustion.

[0071] Based on the above analysis, the change of carbon monoxide concentration data and carbon dioxide concentration data of each beam tube measuring point at the tth time and before each time, and the correlation between carbon monoxide concentration data, carbon dioxide concentration data and oxygen concentration data of each beam tube measuring point at the tth time and before each time are obtained. The change rate of residual coal oxidation of each beam tube measuring point at the tth time is obtained, which is:

[0072] Based on the above analysis, the correlation between carbon monoxide concentration data, carbon dioxide concentration data and oxygen concentration data of each beam tube measuring point at the tth time and before each time is calculated, and is recorded as the first correlation and the second correlation.

[0073] ​All carbon monoxide and carbon dioxide concentration data of each bundle tube measuring point at time t and before are arranged in ascending order of goaf depth to form the carbon monoxide concentration sequence and carbon dioxide concentration sequence of each bundle tube measuring point at time t. The fitting curve functions of the carbon monoxide concentration sequence and carbon dioxide concentration sequence of each bundle tube measuring point at time t are denoted as the first fitting curve function and the second fitting curve function, respectively, where the horizontal axis is the goaf depth. The derivative values ​​of the first fitting curve function and the second fitting curve function at the goaf depth of each bundle tube measuring point at time t are denoted as the first derivative value and the second derivative value, respectively.

[0074] The expression for the rate of change of residual coal oxidation at each measuring point of the bundle tube at time t is:

[0075] In the formula, This represents the rate of change of residual coal oxidation at any of the bundle tube measuring points at time t. , Let represent the first correlation degree and the second correlation degree of any bundle tube measuring point at time t, respectively; , Let represent the absolute values ​​of the first derivative and the second derivative at any bundle tube measuring point at time t, respectively. Let it be the first product, and... This is denoted as the second product.

[0076] In this embodiment, the correlation between carbon monoxide concentration data, carbon dioxide concentration data, and oxygen concentration data at each bundle tube measuring point before and at time t is calculated using the grey relational analysis method. The grey relational analysis method is a known technology. As other implementation methods, based on the ability to measure the correlation between carbon monoxide concentration data, carbon dioxide concentration data, and oxygen concentration data at each bundle tube measuring point before and at time t, implementers may adopt other existing feasible technologies. This application does not impose any special restrictions.

[0077] In this embodiment, the least squares method is used to obtain the first fitting curve function and the second fitting curve function respectively. The least squares method is a well-known technique and will not be described in detail in this application. As other implementation methods, based on the ability to obtain the first fitting curve function and the second fitting curve function, the implementer may select other existing feasible techniques. This application does not impose any special restrictions.

[0078] It should be noted that: The rate of change in the oxidation reaction of residual coal is reflected by the carbon monoxide concentration in the goaf. The higher the correlation between oxygen concentration and carbon monoxide concentration in the goaf, the better. The greater the carbon monoxide produced by the oxidation reaction of residual coal is, the more the carbon monoxide concentration change feature can evaluate the degree of the oxidation reaction of residual coal, and The greater the change rate of the product carbon monoxide concentration is, the greater the change rate of the oxidation reaction of residual coal is, The greater the change rate of the product carbon monoxide concentration is, the greater the change rate of the oxidation reaction of residual coal is, The greater the correlation between the oxygen concentration and the carbon dioxide concentration in the goaf is, The greater the carbon dioxide produced by the oxidation reaction of residual coal is, the more the carbon dioxide concentration change feature can evaluate the degree of the oxidation reaction of residual coal, and The greater the change rate of the product carbon dioxide concentration is, the greater the change rate of the oxidation reaction of residual coal is, The greater the change rate of the product carbon dioxide concentration is, the greater the change rate of the oxidation reaction of residual coal is.

[0079] Step 2.3, by the change rate of the oxidation reaction of residual coal of each beam tube measuring point at each time, combined with the oxygen concentration abnormal value, the oxygen concentration retention coefficient of each beam tube measuring point at each time is obtained, and then the reliable oxygen concentration data at each time is obtained from the oxygen concentration data of all beam tube measuring points at each time and before each time.

[0080] The greater the change rate of the oxidation reaction of residual coal at the tth time is, the more significant the change of the oxidation reaction of residual coal in the goaf at the tth time is, and the more likely the goaf at the tth time is near the boundary of the spontaneous combustion "three zones". At the same time, in order to prevent the spontaneous combustion of residual coal in the goaf, the working face advancing speed and the goaf fire prevention and extinguishing are provided with decision basis, the gas concentration data reflecting the boundary of the spontaneous combustion "three zones" should be paid more attention to, and the abnormal oxygen concentration data of the boundary of the spontaneous combustion "three zones" should be removed.

[0081] Further, by the change rate of the oxidation reaction of residual coal of each beam tube measuring point at the tth time and the oxygen concentration abnormal value, the oxygen concentration retention coefficient of each beam tube measuring point at the tth time is obtained, specifically:

[0082] The reciprocal of the sum of the oxygen concentration abnormal value of each beam tube measuring point at the tth time and the preset positive number is calculated, the reciprocal is mapped to a value greater than 1; the value obtained by mapping is taken as the base number of the exponential function with the change rate of the oxidation reaction of residual coal of each beam tube measuring point at the tth time as the index; the calculation result of the exponential function is taken as the oxygen concentration retention coefficient of each beam tube measuring point at the tth time.

[0083] In this embodiment, the expression of the oxygen concentration retention coefficient of each beam tube measuring point at the tth time is:

[0084] In the formula, represents the oxygen concentration retention coefficient of any beam tube measuring point at the tth time; represents the oxygen concentration abnormal value of any beam tube measuring point at the tth time. represents the residual coal oxidation change rate of the any one beam tube measuring point at the tth moment; a represents a preset positive number, and the role is to prevent the denominator from being 0, the value of a is artificially preset, and the value of a in the embodiment is 0.01; the calculation The sum of 1 is to prevent the base number of the exponential function from being less than 1.

[0085] It should be noted that: for reflecting the importance of the gas concentration data of the goaf at the depth at the tth moment, The greater the value is, the more likely the goaf at the depth is near the boundary of the spontaneous combustion “three zones”; in order to realize accurate division of the spontaneous combustion “three zones”, the oxygen concentration data of the goaf at the depth should have a greater authenticity requirement, for reflecting the authenticity of the oxygen concentration data of the goaf at the depth, The greater the value is, the more similar the oxygen concentration data distribution of the same measuring point is, and the more the oxygen concentration data should be retained, The greater the value is, the more reliable the oxygen concentration data is, and the more the oxygen concentration data should be retained.

[0086] Further, in order to avoid the influence of factors such as dust and coal slurry flooding, pipeline gas leakage and the like in the measurement process, the oxygen concentration data with lower abnormal value and higher value should be retained, the oxygen concentration retention coefficients of all beam tube measuring points at all moments are normalized, and then reliable oxygen concentration data at each moment is selected from the oxygen concentration data of all beam tube measuring points at each moment and before each moment, and is used to construct the oxygen concentration measurement graph of the air inlet side and the oxygen concentration measurement graph of the air return side. Specifically,

[0087] For the air inlet side, the oxygen concentration data corresponding to the oxygen concentration retention coefficient with a normalized result greater than a preset retention threshold is retained, the retained oxygen concentration data is taken as reliable oxygen concentration data, and the oxygen concentration measurement graph of the air inlet side is constructed with the goaf depth as the horizontal coordinate and the oxygen concentration data as the vertical coordinate. Figure 3 The selection process of reliable oxygen concentration data is shown in the schematic diagram.

[0088] For the air return side, the oxygen concentration data corresponding to the oxygen concentration retention coefficient with a normalized result greater than a preset retention threshold is retained, and the oxygen concentration measurement graph of the air return side is constructed with the goaf depth as the horizontal coordinate and the oxygen concentration data as the vertical coordinate.

[0089] In the embodiment, the value of the preset retention threshold is 0.4, the greater the value of the preset retention threshold is, the lower the tolerance of abnormal data of the goaf oxygen concentration monitoring is, and the higher the accuracy requirement is, and the value of the preset retention threshold is artificially preset, and the implementer can set the value of the preset retention threshold according to the actual situation.

[0090] In this embodiment, the Min-Max normalization method is used to normalize the oxygen concentration retention coefficient. The Min-Max normalization method is a known technology, and will not be described here.

[0091] Step 3: By the actual size of the working face, goaf, air inlet roadway and air return roadway at each time and each time before the time, the oxygen concentration simulation distribution map of the goaf at each time is simulated, and the simulation oxygen concentration data of each reliable oxygen concentration data is obtained from the oxygen concentration simulation distribution map to compare the simulation difference of each reliable oxygen concentration data, so as to extract the oxygen concentration simulation value from the oxygen concentration simulation distribution map, and the reliable oxygen concentration data is used together for spontaneous combustion three-zone division of the ventilation side.

[0092] The numerical simulation is not limited by the site conditions, and the beam tube site monitoring result is not much different from the numerical simulation result. By the actual size of the working face, goaf, air inlet roadway and air return roadway at each time and each time before the time, the oxygen concentration simulation distribution map of the goaf at each time is simulated, and the oxygen concentration simulation distribution map of the goaf at each time is simulated. Specifically, taking the tth time as an example, at the tth time, the actual size of the coal mine working face, goaf, air inlet roadway and air return roadway is obtained as the underground coal mining geometric model parameters, the working face size specifically includes the cross section length, width, height; the goaf size includes the strike length, tendency length, caving zone height, fracture zone height; the air inlet roadway size is the cross section width and height; the air return roadway size is the cross section width and height, and the underground coal mining geometric model is established.

[0093] At the same time, in order to simplify the numerical simulation model of the oxygen concentration in the goaf, the goaf is approximately regarded as a porous medium area, it is assumed that the model gas is an incompressible ideal gas, the flow mode is turbulent motion, the air volume is set to 1440m 3 / min, the velocity inlet boundary is used for the import boundary, the gas volume fraction at the air inlet is set to: 21%, 79%, the environmental temperature is set to , and the air inlet velocity is set to 1.6m / s. The oxygen concentration simulation distribution map of the goaf at z=0.1m is obtained by solving the FLUENT software. According to the method of obtaining the oxygen concentration simulation distribution map of the goaf, the oxygen concentration simulation distribution map of the goaf is obtained.

[0094] The positions of the air inlet side beam tube measuring points 711 and 712 are recorded, all the simulation oxygen concentration data with the same position as the beam tube measuring points 711 and 712 in the oxygen concentration simulation distribution map of the goaf at each time are obtained, and the oxygen concentration simulation curve of the air inlet side at the tth time is composed in the order of the goaf depth from small to large.

[0095] According to the method for obtaining the air inlet side oxygen concentration simulation curve at the t-th moment, the air inlet side oxygen concentration simulation curve at the t-th moment is obtained for the beam tube measuring points 721 and 722 on the air return side.

[0096] For the air inlet side, the air inlet side oxygen concentration measured graph is constructed by the goaf depth and the collected oxygen concentration data. For each oxygen concentration data in the air inlet side oxygen concentration measured graph, the simulated oxygen concentration data with the same goaf depth is found from the air inlet side oxygen concentration simulation curve. The deviation value between each reliable oxygen concentration data and the simulated oxygen concentration data is calculated. The ratio of the deviation value to each reliable oxygen concentration data is taken as the simulation difference degree of each reliable oxygen concentration data. The simulated oxygen concentration data corresponding to each reliable oxygen concentration data with the simulation difference degree less than or equal to the preset difference threshold value is selected. The oxygen concentration simulation value and the goaf depth at the adjacent position of the location of the selection result in the oxygen concentration simulation distribution graph are extracted. The extraction result is inserted into the air inlet side oxygen concentration measured graph to increase the number of data in the air inlet side oxygen concentration measured graph and improve the accuracy of the spontaneous combustion "three-zone" division. The insertion method is as follows: taking the goaf depth as the horizontal coordinate and the oxygen concentration simulation value as the vertical coordinate, the oxygen concentration measured data points are formed and inserted into the air inlet side oxygen concentration measured graph.

[0097] In this embodiment, the value of the preset difference threshold value is 0.9. The value of the preset difference threshold value is preset by human and can be set by the implementer according to the actual situation. The present application does not make special limitations.

[0098] In this embodiment, the adjacent positions of the location of the simulated oxygen concentration data are positions with a goaf depth difference of 0.1 m, 0.2 m, -0.1 m and -0.2 m from the location of the simulated oxygen concentration data. 0.1 m, 0.2 m, -0.1 m and -0.2 m are only one embodiment of the present application. The implementer can set the specific value according to the actual situation. The present application does not make special limitations.

[0099] According to the finally obtained air inlet side oxygen concentration measured graph, the air inlet side oxygen concentration monitoring curve is constructed. According to the method for obtaining the air inlet side oxygen concentration monitoring curve, the air return side oxygen concentration monitoring curve is obtained. Then, the spontaneous combustion "three-zone" division of the goaf air inlet side and the air return side is realized based on the critical oxygen concentration method, wherein the oxygen concentration critical value is 18% and 8%, respectively.

[0100] In addition, the present application adopts the following inert coupling gas fire extinguishing equipment system to prevent and extinguish the fire in the underground goaf. The schematic diagram of the inert coupling gas fire extinguishing equipment system is shown in Figure 4 . Figure 41 is a working face, 2 is a goaf, 11 is a nitrogen generator, 12 is a liquid carbon dioxide tank truck, 13 is an inert gas coupling fire extinguishing device, 131 is a coal, electric water bath type vaporizer, 132 is a balance tank, 14 is a conveying pipeline, 15 is the ground, and 16 is an underground pipeline.

[0101] The inert gas coupling fire extinguishing equipment system is composed of a ground liquid carbon dioxide tank truck, a nitrogen generator, a conveying pipeline, an inert gas coupling fire extinguishing device and an underground pipeline.

[0102] The liquid carbon dioxide tank truck and the inert gas coupling fire extinguishing device are placed near the nitrogen generator, the outlet of the nitrogen generator is connected to the inlet of the balance tank of the inert gas coupling fire extinguishing device through the conveying pipeline, the outlet of the liquid carbon dioxide tank truck is connected to the inlet of the coal, electric water bath type vaporizer of the inert gas coupling fire extinguishing device, the gas outlet of the coal, electric water bath type vaporizer is connected to the inlet of the balance tank, and the gas outlet of the balance tank is connected to the underground pipeline.

[0103] The working process of the inert gas coupling fire extinguishing equipment system is as follows: the nitrogen generator is started, nitrogen is conveyed into the balance tank of the inert gas coupling fire extinguishing device, at the same time, the liquid carbon dioxide in the liquid carbon dioxide tank truck is input into the coal, electric water bath type vaporizer of the inert gas coupling fire extinguishing device, vaporized into carbon dioxide gas, then input into the balance tank according to a certain proportion, coupled with nitrogen to form inert coupling gas, and injected into the goaf of the working face of the easily self-igniting coal seam underground through the underground pipeline, so as to realize the fire extinguishing treatment of the goaf underground.

[0104] Based on the same inventive concept as the above method, the embodiments of the present application also provide a goaf oxygen concentration monitoring system, comprising:

[0105] A concentration monitoring module is configured to collect oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measuring point in real time at different positions of the goaf ventilation side.

[0106] A concentration analysis module is configured to obtain oxygen concentration abnormal values of each measuring point at each time point by comparing oxygen concentration data of each measuring point at each time point with oxygen concentration data of each measuring point at adjacent time points, and comparing oxygen concentration data of all measuring points at each time point; obtain the oxidation change rate of residual coal of each measuring point at each time point by the change of carbon monoxide concentration data and carbon dioxide concentration data of each measuring point at each time point and before each time point, and the correlation between carbon monoxide concentration data, carbon dioxide concentration data and oxygen concentration data of each measuring point at each time point and before each time point; obtain the oxygen concentration retention coefficient of each measuring point at each time point by combining the oxygen concentration abnormal values; and further screen reliable oxygen concentration data of each time point from oxygen concentration data of all measuring points at each time point and before each time point.

[0107] The spontaneous combustion three-zone division module is used for obtaining the oxygen concentration simulation distribution diagram of the goaf at each time point by simulating the actual size of the working face, the goaf, the air inlet roadway and the air return roadway at each time point and before each time point, and obtaining the simulation oxygen concentration data of the reliable oxygen concentration data from the oxygen concentration simulation distribution diagram according to the positions of the measuring points, comparing the simulation oxygen concentration data, obtaining the simulation difference degree of the reliable oxygen concentration data, and extracting the oxygen concentration simulation value from the oxygen concentration simulation distribution diagram, which is used for spontaneous combustion three-zone division of the ventilation side together with the reliable oxygen concentration data.

[0108] Based on the same inventive concept as the above method, the embodiments of the present application also provide a goaf oxygen concentration monitoring device, which comprises a memory, a processor and a computer program stored in the memory and running on the processor, and the processor implements the steps of any one of the above goaf oxygen concentration monitoring methods when executing the computer program.

[0109] In summary, the present application can effectively detect abnormal conditions in goaf oxygen concentration monitoring data by calculating oxygen concentration outliers, which helps to improve the accuracy of subsequent spontaneous combustion three-zone division; by calculating the residual coal oxidation change rate, the strength change of the residual coal oxidation reaction in the goaf can be measured, which helps to identify areas with intense oxidation reaction and close to the boundary of the spontaneous combustion "three-zone", and at the same time, combined with the oxygen concentration outliers, the reliability of each oxygen concentration data for spontaneous combustion "three-zone" division is quantified, high-value oxygen concentration monitoring data is retained, and the influence of factors such as dust, coal slurry flooding and pipeline leakage is avoided, to ensure the accuracy of spontaneous combustion "three-zone" division;

[0110] Further, combined with numerical simulation and field monitoring data, the field monitoring data is supplemented, the amount of data for spontaneous combustion "three-zone" division is increased, and spontaneous combustion "three-zone" division can be more accurately realized, which provides more accurate decision basis for fire prevention engineering.

[0111] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0112] It is apparent that a person skilled in the art can make a variety of modifications to the application described herein, without departing from the spirit and scope of the application. Therefore, the described embodiments are to be considered in all respects as illustrative and not restrictive.

Claims

1. A method of monitoring oxygen concentration in a gob, characterized by, The method comprises the following steps: presetting measurement points at different positions of the ventilation side of the goaf, collecting oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measurement point in real time; calculating the difference between the oxygen concentration data of each measurement point at each time and the oxygen concentration data of the adjacent previous time; the number of measurement points is 2, and the difference between the oxygen concentration data of each measurement point and the oxygen concentration data of the other measurement point at each time is calculated; the oxygen concentration abnormal value of each measurement point at each time is the normalized value of the product of the positive proportional mapping result of the difference and the difference amount; the distance from each measurement point to the working face is obtained in real time, which is recorded as the depth of each goaf; the correlation between the carbon monoxide concentration data and the carbon dioxide concentration data of each measurement point at each time and before each time and the oxygen concentration data is recorded as a first correlation and a second correlation, respectively; the fitting curve functions of the carbon monoxide concentration data and the carbon dioxide concentration data of each measurement point at each time and before each time are recorded as a first fitting curve function and a second fitting curve function, respectively, wherein the abscissa is the depth of the goaf; the derivative values of the first fitting curve function and the second fitting curve function at the depth of each measurement point of each goaf at each time are recorded as a first derivative value and a second derivative value, respectively; the residual coal oxidation change rate of each measurement point at each time is obtained through the first correlation, the first derivative value, the second correlation and the second derivative value, the reciprocal of the sum of the oxygen concentration abnormal value and a preset positive number is calculated, and the reciprocal is mapped to a value greater than 1; the value obtained by mapping is used as the base number of an exponential function with the residual coal oxidation change rate as the index; the oxygen concentration retention coefficient of each measurement point at each time is the calculation result of the exponential function, and each oxygen concentration data corresponding to the oxygen concentration retention coefficient with a normalized result greater than a preset retention threshold is used as each reliable oxygen concentration data; by the actual sizes of the working face, the goaf, the air inlet roadway and the air return roadway at each time and before each time, the oxygen concentration simulation distribution map of the goaf at each time is simulated, and the simulation oxygen concentration data of the reliable oxygen concentration data is obtained from the map for comparison to obtain the simulation difference degree of the reliable oxygen concentration data, so that the oxygen concentration simulation value is extracted from the oxygen concentration simulation distribution map and used together with the reliable oxygen concentration data for spontaneous combustion three-zone division of the ventilation side.

2. The method of monitoring oxygen concentration in a goaf according to claim 1, wherein, The method for obtaining the residual coal oxidation change rate is: the product of the first correlation and the absolute value of the first derivative value is recorded as a first product; the product of the second correlation and the absolute value of the second derivative value is recorded as a second product; the residual coal oxidation change rate is the sum of the first product and the second product.

3. The method of monitoring oxygen concentration in a gob as recited in claim 1, wherein, The obtaining process of the simulation difference degree is: the deviation value between the reliable oxygen concentration data and the simulation oxygen concentration data thereof is calculated, and the simulation difference degree is the ratio of the deviation value to the reliable oxygen concentration data.

4. The goaf oxygen concentration monitoring method of claim 1, wherein, The oxygen concentration simulation value extracted from the oxygen concentration simulation distribution map and used together with the reliable oxygen concentration data for spontaneous combustion three-zone division of the ventilation side comprises: The simulated oxygen concentration data of the reliable oxygen concentration data corresponding to the simulated difference degree less than or equal to the preset difference threshold is selected, and the oxygen concentration simulation value at the adjacent position of the position of the selection result in the oxygen concentration simulation distribution diagram and the goaf depth are extracted; An oxygen concentration monitoring curve is constructed according to the extraction result and the reliable oxygen concentration data, and is used for spontaneous combustion three-zone division of the ventilation side.

5. A gob oxygen concentration monitoring system using the gob oxygen concentration monitoring method according to claim 1, characterized by, The oxygen concentration monitoring system comprises: A concentration monitoring module is configured to collect oxygen concentration data, carbon monoxide concentration data and carbon dioxide concentration data of each measuring point in real time at preset measuring points at different positions of the ventilation side of the goaf. A concentration analysis module is configured to obtain oxygen concentration outliers of each measuring point at each time by comparing oxygen concentration data of each measuring point at each time and adjacent time, and comparing oxygen concentration data of all measuring points at each time; obtain oxidation change rates of each measuring point at each time by changes of carbon monoxide concentration data and carbon dioxide concentration data of each measuring point at each time and before the time, and correlation between carbon monoxide concentration data, carbon dioxide concentration data and oxygen concentration data of each measuring point at each time and before the time; obtain oxygen concentration retention coefficients of each measuring point at each time by combining the oxygen concentration outliers and the oxidation change rates; and further screen reliable oxygen concentration data at each time from oxygen concentration data of all measuring points at each time and before the time. A spontaneous combustion three-zone division module is configured to simulate oxygen concentration simulation distribution diagrams of the goaf at each time by actual sizes of the working face, the goaf, the air inlet roadway and the air return roadway at each time and before the time, and obtain simulated oxygen concentration data of the reliable oxygen concentration data by comparing the simulated oxygen concentration data of the reliable oxygen concentration data from the oxygen concentration simulation distribution diagrams according to positions of the measuring points, to extract oxygen concentration simulation values from the oxygen concentration simulation distribution diagrams, and to use the oxygen concentration simulation values and the reliable oxygen concentration data for spontaneous combustion three-zone division of the ventilation side.

6. A goaf oxygen concentration monitoring apparatus comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, The processor executes the computer program to realize the steps of the goaf oxygen concentration monitoring method according to any one of claims 1-4.

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