CN116151612A - Method for classifying spontaneous combustion dangerous grades of coals with different metamorphism degrees - Google Patents
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 40
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Abstract
The invention discloses a method for classifying coal spontaneous combustion danger grades with different metamorphism degrees, which comprises the following steps: selecting multiple groups of coal samples with different varieties and different deterioration degrees, and respectively performing low-temperature oxidation temperature programming experiments on the coal to obtain CO and C 2 H 4 Obtaining the initial temperatures of two gases according to the change curve of the temperature; then fitting by using a Logistic regression function respectively; furthermore, normal inspection is carried out on the initial temperature and fitting parameters of the coal sample respectively to obtain median or average value; obtaining a first inflection point temperature and a second inflection point temperature of CO according to the Logistic functionAnd a third inflection point temperature; finally, the initial temperature of CO and C 2 H 4 The 5 characteristic temperatures of the initial temperature, the CO first inflection point temperature, the CO second inflection point temperature and the CO third inflection point temperature are critical values, and the coal spontaneous combustion dangerous grade state is divided. The invention provides a coal spontaneous combustion danger grade classification method aiming at coal samples with different deterioration degrees for the first time, and provides a new thought for guiding the accurate control of spontaneous combustion of working face coal.
Description
Technical Field
The invention relates to the field of coal spontaneous combustion early warning, in particular to a method for classifying coal spontaneous combustion danger grades with different metamorphic degrees.
Background
Under the coal mine, spontaneous combustion of coal is one of main disasters affecting safe stoping of working faces, and the deterioration degree of coal has obvious influence on the change rule of spontaneous combustion early warning indexes of coal. The existing coal spontaneous combustion early warning is mainly carried out by CO and O 2 The concentration and the like are used as indexes to judge the spontaneous combustion risk degree of the coal, but the concentration of the gas changesThe degradation is affected by a plurality of factors, including whether the ventilation system is stable, the mining speed, the roof collapse and the like, and the probability of misjudgment is high. The temperature is the most direct factor for representing the spontaneous combustion degree of the coal, and is less influenced by the outside. At present, the coal spontaneous combustion early warning does not consider the influence of the deterioration degree of coal on early warning indexes, so that the application range of the existing early warning system is limited. In view of the above problems, it is necessary to provide a more reasonable and effective method for constructing a coal spontaneous combustion danger classification method aiming at coal samples with different deterioration degrees, so as to ensure the high efficiency and effectiveness of coal spontaneous combustion early warning.
Disclosure of Invention
The invention aims to provide a method for classifying coal spontaneous combustion danger grades with different metamorphic degrees, which improves coal spontaneous combustion early warning.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a method for classifying coal spontaneous combustion risk grades with different metamorphism degrees, comprising the following steps:
step one, selecting a plurality of groups of coal samples with different types and different deterioration degrees, and respectively performing low-temperature oxidation temperature programming experiments on the coal to obtain marking gases CO and C 2 H 4 The CO and the C are obtained along with the change curve of the coal temperature 2 H 4 Is a first-occurrence temperature of (a);
step two, CO and C of each group of coal samples 2 H 4 Respectively carrying out normal examination on the initial temperature to respectively obtain CO and C 2 H 4 Average value of initial temperature;
fitting a curve of CO changing along with the temperature by using a Logistic regression function to obtain a fitting equation;
step four, determining three characteristic temperatures of each group of coal samples according to a fitting equation: a first inflection point temperature, a second inflection point temperature, and a third inflection point temperature;
step five, respectively carrying out normal inspection on the first inflection point temperature, the second inflection point temperature and the third inflection point temperature of each group of coal samples, and obtaining an average value of the three inflection point temperatures for each metamorphic coal sample;
step six, using the initial temperature of CO and C 2 H 4 First-occurrence temperature, CO first inflection point temperature and CO second inflection pointThe 5 characteristic temperatures of the point temperature and the third inflection point temperature of CO are critical values, and the coal spontaneous combustion dangerous grade state is divided: safety, low risk, risk of stroke, high risk, and catastrophe condition.
As a preferred aspect of the present invention, the coal spontaneous combustion dangerous level state in the sixth step is indicated as follows: the temperature is less than the initial temperature of CO, so that the method is safe; a CO initial temperature of greater than or equal to the first occurrence temperature of less than C 2 H 4 The initial temperature is low in risk; c is greater than or equal to C 2 H 4 The initial temperature is less than the first inflection point temperature of CO, and medium risk is achieved; the temperature of the first inflection point of CO is higher than or equal to that of the second inflection point of CO, so that the risk is high; and the temperature of the third inflection point of CO is more than or equal to the temperature of the third inflection point of CO, and the catastrophe state is achieved.
In the first step, 3 groups of coal samples with low deterioration degree, coal samples with medium deterioration degree and coal samples with high deterioration degree are selected.
As a preferred aspect of the present invention, the fitting process of the fitting equation in step three is: (1) Four parameters A for determining a Logistic function based on statistics 1 、A 2 、x 0 、p 0 The method comprises the steps of carrying out a first treatment on the surface of the (2) Carrying out normal inspection on the four parameters to obtain respective average values; (3) Substituting the average value into a Logistic regression function to obtain a model of the change of the CO concentration along with the temperature.
As a preferred embodiment of the present invention, the specific steps of the coal low-temperature oxidation temperature programming experiment in the step one are: (1) Placing the crushed coal sample in a coal sample tank in a temperature programming box, connecting a gas circuit and a temperature probe, checking air tightness, and introducing 50mL/min of dry air; (2) And (3) heating, when the temperature in the coal sample tank reaches the specified test temperature, taking a gas sample after the temperature is constant, and analyzing the gas components and the concentration by using a gas chromatograph.
Compared with the prior art, the coal spontaneous combustion danger classification method aiming at the coal samples with different deterioration degrees is provided for the first time, a new thought is provided for guiding the accurate control of the spontaneous combustion of the coal on the working face, and the effectiveness of the coal spontaneous combustion early warning is ensured.
Drawings
FIG. 1 is a graph showing the CO concentration of three groups of low metamorphic coal samples as a function of temperature and fitting the graph.
FIG. 2 is a graph of three groups of low metamorphic coal samples C 2 H 4 Concentration as a function of temperature and fitting a curve.
FIG. 3 shows a low deterioration degree coal sample C 2 H 4 Normal check-up of the initial temperature.
Fig. 4 is a normal test plot of low metamorphic coal sample CO concentration fitting four sets of parameters.
FIG. 5 is a graph of a low metamorphic coal sample Logistic fit equation.
FIG. 6 is a graph of the classification of the spontaneous combustion level of a coal sample with low deterioration.
FIG. 7 is a graph showing the classification of the spontaneous combustion level of coal samples with medium deterioration degree.
FIG. 8 is a graph of the classification of the spontaneous combustion level of a coal sample with a high deterioration degree.
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific examples.
The invention provides a method for classifying spontaneous combustion dangerous grades of coal with different metamorphic degrees, which aims at 3 coal samples with different metamorphic degrees: low (long flame coal: D1, D2, D3), medium (fat coal, coking coal, fat coal: Z1, Z2, Z3) and high (lean coal, lean coal: G1, G2, G3) were tested separately.
Example 1: coal sample with low deterioration degree
Step one: the curve of CO variation with temperature obtained by the low-temperature oxidation temperature programming experiment of coal is shown in figure 1, C 2 H 4 The concentration as a function of temperature is shown in FIG. 2, respectively.
The specific steps of the coal low-temperature oxidation temperature programming experiment are as follows: (1) Placing the crushed coal sample (50-80 meshes) in a coal sample tank in a temperature programming box, connecting a gas circuit and a temperature probe, checking air tightness, and introducing 50mL/min of dry air; (2) And (3) heating, when the temperature in the coal sample tank reaches the specified test temperature, taking a gas sample after the temperature is constant for 5min, and analyzing the gas components and the concentration by using a gas chromatograph.
Step two: the initial CO temperatures corresponding to the coal samples with low deterioration degree in FIG. 1 are all 30 ℃, and C in FIG. 2 can be obtained 2 H 4 Is at the initial temperature of (2)110 ℃, 120 ℃ and 120 ℃, respectively. C (C) 2 H 4 Initial temperature normal test as shown in fig. 3, the average temperature was taken to be 117 ℃.
Step three: wherein the Logistic function equation is:
wherein y is the volume fraction of the marking gas,%; a is that 2 The maximum value corresponding to the model; a is that 1 The minimum value corresponding to the model; x is the temperature of the coal, and the temperature is lower than the temperature; x is x 0 Is the inflection point of the curve; p is p 0 Is the amount at the inflection point of the curve that is related to the slope of the curve.
CO was fitted according to the Logistic function in fig. 1, and the fitting parameters are shown in table 1.
TABLE 1 fitting parameters for CO concentration of coal samples with low deterioration degree
| A 1 | A 2 | x 0 | p 0 |
| 79.76619 | 13651.47 | 257.98 | 11.9711 |
| 42.49296 | 12881.27 | 269.83 | 11.57086 |
| 34.18399 | 15379.8 | 270.88 | 10.24304 |
For four sets of parameters (A 1 、A 2 、x 0 、p 0 ) A normal test was performed, as shown in fig. 4, resulting in four sets of parameters with average values of 52, 13971, 266, and 11, respectively. The equation of the change of the CO of the low metamorphic coal sample along with the temperature is as follows:
wherein 266 ℃ is the second inflection point temperature of CO.
And fourthly, carrying out local peak searching on the curve of the equation (2) by using Origin drawing software, and obtaining the first inflection point temperature 212 ℃ and the third inflection point temperature 318 ℃ of CO as shown in figure 5.
Step five, selecting the initial temperature (30 ℃) of CO and C 2 H 4 The coal spontaneous combustion was classified by using the initial temperature (117 ℃) and the CO first inflection point temperature (212 ℃) and the second inflection point temperature (266 ℃) and the CO third inflection point temperature (318 ℃) as indexes, and the classification results are shown in FIG. 6. It can be seen that below 30 ℃ is the safe zone, 30-117 ℃ is low risk, 117-212 ℃ is medium risk, 212-266 ℃ is high risk, 266-318 ℃ is the catastrophe state.
Example 2: coal sample with medium deterioration degree
The method for classifying the spontaneous combustion grades of the coal sample with medium deterioration degree is the same as that of example 1, and the classification result of the spontaneous combustion danger grades of the coal is shown in fig. 7. It can be seen that below 30 ℃ is a safe zone, 30-123 ℃ is a low risk, 123-232 ℃ is a medium risk, 232-281 ℃ is a high risk, 281-328 ℃ is a catastrophe state.
Example 3: coal sample with high deterioration degree
The method for classifying the spontaneous combustion grades of the coal sample with high deterioration degree is the same as that of the embodiment 1, and the classification result of the spontaneous combustion danger grades of the coal is shown in fig. 8. It can be seen that below 30 ℃ is the safety zone, 30-137 ℃ is the low risk, 137-267 ℃ is the medium risk, 267-327 ℃ is the high risk, 327-386 ℃ is the catastrophe state.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (5)
1. A method for classifying coal spontaneous combustion risk grades with different metamorphic degrees, which is characterized by comprising the following steps:
step one, selecting a plurality of groups of coal samples with different types and different deterioration degrees, and respectively performing low-temperature oxidation temperature programming experiments on the coal to obtain marking gases CO and C 2 H 4 The CO and the C are obtained along with the change curve of the coal temperature 2 H 4 Is a first-occurrence temperature of (a);
step two, CO and C of each group of coal samples 2 H 4 Respectively carrying out normal examination on the initial temperature to respectively obtain CO and C 2 H 4 Average value of initial temperature;
fitting a curve of CO changing along with the temperature by using a Logistic regression function to obtain a fitting equation;
step four, determining three characteristic temperatures of each group of coal samples according to a fitting equation: a first inflection point temperature, a second inflection point temperature, and a third inflection point temperature;
step five, respectively carrying out normal inspection on the first inflection point temperature, the second inflection point temperature and the third inflection point temperature of each group of coal samples, and obtaining an average value of the three inflection point temperatures for each metamorphic coal sample;
step six, using the initial temperature of CO and C 2 H 4 The 5 characteristic temperatures of the initial temperature, the CO first inflection point temperature, the CO second inflection point temperature and the CO third inflection point temperature are critical values, and the coal spontaneous combustion dangerous grade state is divided.
2. The method for classifying coal spontaneous combustion risk levels according to claim 1, wherein the indexes of the coal spontaneous combustion risk level states in the sixth step are: the temperature is less than the initial temperature of CO, so that the method is safe; a CO initial temperature of greater than or equal to the first occurrence temperature of less than C 2 H 4 The initial temperature is low in risk; c is greater than or equal to C 2 H 4 The initial temperature is less than the first inflection point temperature of CO, and medium risk is achieved; the temperature of the first inflection point of CO is higher than or equal to that of the second inflection point of CO, so that the risk is high; and the temperature of the third inflection point of CO is more than or equal to the temperature of the third inflection point of CO, and the catastrophe state is achieved.
3. The method for classifying spontaneous combustion risk levels of coal having different levels of deterioration according to claim 1, wherein in the first step, 3 groups of the low-level coal, the medium-level coal and the high-level coal are selected.
4. The method for classifying coal spontaneous combustion risk levels according to claim 1, wherein the fitting process of the fitting equation in the third step is: (1) Four parameters A for determining a Logistic function based on statistics 1 、A 2 、x 0 、p 0 The method comprises the steps of carrying out a first treatment on the surface of the (2) Carrying out normal inspection on the four parameters to obtain respective average values; (3) Substituting the average value into a Logistic regression function to obtain a model of the change of the CO concentration along with the temperature.
5. The method for classifying coal spontaneous combustion risk levels with different deterioration degrees according to claim 1, wherein the specific steps of the coal low-temperature oxidation temperature programming experiment in the step one are as follows: (1) Placing the crushed coal sample in a coal sample tank in a temperature programming box, connecting a gas circuit and a temperature probe, checking air tightness, and introducing 50mL/min of dry air; (2) And (3) heating, when the temperature in the coal sample tank reaches the specified test temperature, taking a gas sample after the temperature is constant, and analyzing the gas components and the concentration by using a gas chromatograph.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116864024A (en) * | 2023-09-05 | 2023-10-10 | 中国矿业大学(北京) | Coal spontaneous combustion tendency judging method and system based on carbon monoxide generation index |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116864024A (en) * | 2023-09-05 | 2023-10-10 | 中国矿业大学(北京) | Coal spontaneous combustion tendency judging method and system based on carbon monoxide generation index |
| CN116864024B (en) * | 2023-09-05 | 2023-12-01 | 中国矿业大学(北京) | Coal spontaneous combustion tendency judging method and system based on carbon monoxide generation index |
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