Method for characterizing gas desorption law in gas-containing coal crushing process

Abstract

The present application belongs to the field of porous solid medium gas desorption diffusion determination, and relates to a method for characterizing gas desorption law in a coal crushing process, comprising the following steps: step 1, washing and drying the coal sample; step 2, measuring and counting the particle size characteristics and morphology of the coal sample to obtain the characteristic parameters of the particle size and morphology of the coal sample before crushing; step 3, testing the gas adsorption amount of the coal sample before crushing; step 4, crushing the coal sample and measuring the gas desorption amount of the coal sample during the crushing process; step 5, analyzing and comparing the characteristic parameters of the particle size and morphology of the coal sample before and after crushing to obtain the characteristic change parameters; step 6, according to the characteristic change parameters, analyzing and comparing the change degree of the gas desorption degree with the particle size characteristic or morphology characteristic change parameters to screen out the characteristic change parameters for characterizing the gas desorption degree; and step 7, calculating the gas desorption law characterization parameters in the coal crushing process by combining the gas desorption amount with the characteristic change parameters.

Description

Technical Field

[0001] The invention belongs to the field of gas desorption and diffusion measurement in porous solid media, and relates to a method for characterizing gas desorption laws in a gas-containing coal crushing process. Background Art

[0002] The stripping and crushing of coal is often accompanied by the escape of gas, which can easily cause gas accumulation in enclosed underground spaces, posing a hidden danger to coal mine safety production, leading to the suspension of work at the coal mining face, and even triggering disasters such as gas explosions. Understanding the patterns of gas escape is a necessary basis for mine production capacity and ventilation design. In addition, the fracture and crushing of coal during coal and gas outbursts is also accompanied by large amounts of gas escape. Understanding the desorption and diffusion of gas caused by changes in coal particle size can also help prevent and control dynamic disasters such as coal and gas outbursts. Post-mine activities of coal, such as changes in coal size caused by coal washing, storage, and transportation, and the amount of gas escape are closely related to the measurement of methane gas emissions from post-mine activities.

[0003] In summary, it is extremely necessary to understand the gas leakage during the crushing of gas-containing coal. However, the current measurement and characterization methods are mainly aimed at measuring the gas leakage in gas-containing coal of specific particle size. There is still a lack of an effective measurement and characterization method for the gas leakage during the crushing of gas-containing coal.

[0004] Therefore, there is an urgent need for a method to characterize the gas desorption law during the crushing process of gas-containing coal, so as to effectively measure the gas escape during the crushing process of gas-containing coal. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for characterizing the gas desorption law during the crushing process of gas-containing coal, so as to effectively measure the gas escape situation during the crushing process of gas-containing coal.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for characterizing gas desorption law during the crushing process of gas-containing coal comprises the following steps:

[0008] Step 1. Coal sample pretreatment: cleaning and drying the coal sample to remove impurities on the surface of the coal sample, wherein the coal sample is gas-containing coal;

[0009] Step 2. Statistics of particle size and morphology characteristics of coal samples before crushing: Measure and count the particle size characteristics and morphology of the coal samples, and obtain characteristic parameters of the particle size and morphology of the coal samples before crushing;

[0010] Step 3. Coal sample adsorption test: Test the gas adsorption capacity of the coal sample before crushing;

[0011] Step 4. Coal sample crushing and desorption test: crush the coal sample and measure the gas desorption amount of the coal sample during the crushing process;

[0012] Step 5. Statistics of particle size and morphology characteristics of the coal sample after pulverization: The particle size characteristics and morphology of the coal sample after pulverization are measured and statistically analyzed to obtain characteristic parameters of the particle size and morphology of the coal sample after pulverization, and the characteristic parameters are analyzed and compared with the particle size and morphology of the coal sample before pulverization to obtain characteristic change parameters used to represent the degree of change of the particle size characteristics and morphology characteristics of the coal sample before and after pulverization;

[0013] Step 6. Analysis of the sensitivity of desorption degree to coal sample particle size and morphological characteristics: Based on step 5, characteristic change parameters representing the degree of change in particle size or morphological characteristics of the coal sample before and after crushing are obtained. The correlation between the gas desorption degree and the characteristic change parameters of the coal sample particle size and the correlation between the gas desorption degree and the morphological change parameters are analyzed and compared to screen out characteristic change parameters for characterizing the gas desorption degree;

[0014] Step 7. Characterization of the desorption amount during coal sample crushing: The desorption amount measured during coal sample crushing obtained in step 4 is combined with the characteristic change parameters obtained by analysis in step 6 to obtain a method for characterizing the gas desorption amount during coal sample crushing.

[0015] Furthermore, in step 1, the coal sample is cleaned by gas jet cleaning, and cleaning and drying are performed alternately.

[0016] Furthermore, in steps 2 and 5, the particle size of the coal sample is characterized by one of the parameters including triaxial diameter, projection diameter or spherical equivalent diameter, and the morphology of the coal sample is characterized by one of the parameters including shape index, sphericity, roundness, aspect ratio, convexity, angularity index or roughness.

[0017] Furthermore, the coal sample particle size uses the spherical equivalent diameter d as a characteristic parameter.

[0018]

[0019] Where S is the projected area of ​​the coal sample and π is the pi.

[0020] Furthermore, the morphology of the coal sample uses roundness F as a characteristic parameter.

[0021]

[0022] Where S is the projected area of ​​the coal sample, L is the projected circumference of the coal sample, and π is the pi.

[0023] Furthermore, in step 5, the particle size and morphology characteristics of the coal sample before and after crushing are statistically analyzed using the same characterization parameters, and the characteristic change parameter representing the degree of change in particle size or morphology of the coal sample before and after crushing is Ro[];

[0024]

[0025] Among them, x bm 、x am are the characteristic parameters of the particle size or morphology of the coal sample before and after crushing, x bm 、x am When is the characteristic parameter of the particle size of the coal sample before and after crushing, Ro[] is the particle size characteristic change parameter, x bm 、x am When is the characteristic parameter of the morphology of the coal sample before and after crushing, Ro[] is the parameter of the morphological characteristic change.

[0026] Furthermore, the gas adsorption capacity Q of the coal samples before crushing was determined. ad () and the amount of gas desorption during coal sample crushing, and the Q de With Q ad The ratio Qo characterizes the degree of desorption during the crushing process:

[0027]

[0028]

[0029] And according to the size of the ratio Mo[] of Qo to Ro[], the analysis of the desorption sensitivity of the crushing process is expressed, and the characteristic change parameter Ro[] representing the crushing process is determined according to the size of the desorption sensitivity.

[0030] Furthermore, the coal sample particle size uses the sphere equivalent diameter d as the characteristic parameter, and the coal sample morphology uses the roundness F as the characteristic parameter. The particle size and morphology characteristic parameters of the coal sample before crushing are respectively

[0031]

[0032]

[0033] Where S is the projected area of ​​the coal sample, L is the projected circumference of the coal sample, and π is the pi;

[0034] The Ro[] are Ro[] and Ro[] respectively,

[0035]

[0036]

[0037] Where, d 50 Indicates the particle size of 50% of the cumulative distribution of particles, subscripts a and b represent the coal sample after crushing and before crushing, respectively; the Mo[] are Mo[] and Mo[], respectively. When the Mo[]>Mo[],

[0038]

[0039] When Mo[]<Mo[],

[0040]

[0041] The q is a parameter characterizing the gas desorption law during the crushing process of gas-containing coal.

[0042] The beneficial effects of the present invention are:

[0043] The present invention provides a method for characterizing the gas desorption law in the crushing process of gas-containing coal, which combines the statistics of the particle size and morphological characteristics of the gas-containing coal before crushing and the gas adsorption amount, and the desorption diffusion measurement and particle size and morphological characteristics statistics during the crushing process of the gas-containing coal, and analyzes and compares the sensitivity of the desorption degree to the changes in the particle size and morphological characteristics of the coal sample, so as to select characteristic change parameters that match the gas desorption degree in the crushing process of the gas-containing coal from the particle size characteristic change parameters and the morphological characteristic change parameters of the gas-containing coal, and combine them with the gas desorption amount in the crushing process of the gas-containing coal to obtain a method for characterizing the gas desorption amount in the crushing process of the gas-containing coal, thereby effectively measuring and characterizing the gas escape situation in the crushing process of the gas-containing coal, and providing an effective basis for mine production capacity and ventilation design and prevention and control of dynamic disasters such as coal and gas outbursts.

[0044] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0046] Figure 1 Schematic diagram of a flow chart of a method for characterizing gas desorption law in a gas-containing coal crushing process according to the present invention;

[0047] Figure 2 Schematic diagram of the three-axis diameter method and projection of particle size characteristics statistics in the present invention;

[0048] Figure 3 Schematic diagram of the principle of the adsorption-desorption measurement system of the present invention.

[0049] Reference numerals: sample cell 1 , reference tank 2 , gas pipe 3 , first valve 4 , second valve 5 , pressure gauge 6 . DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0051] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0052] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0053] See also Figures 1 to 3 , is a method for characterizing the gas desorption law during the crushing process of gas-containing coal, comprising the following steps:

[0054] Step 1. Coal sample pretreatment mainly involves cleaning and drying the collected coal samples to remove impurities such as scum and coal ash on the surface of the coal samples. Specifically, the cleaning and drying in the coal sample pretreatment are performed alternately, and the coal sample surface is cleaned by gas jet to eliminate small particles of coal dust adhering to the surface of the coal sample.

[0055] Step 2. Measure the particle size and morphological parameters of the coal sample before crushing, refer to Figure 2 , a particle size and morphology scanner is used to measure and count the particle size characteristics and morphology characteristics of the coal sample, and the coal particle size and morphology characteristic parameters are characterized; in this example, the spherical equivalent diameter (equivalent circle diameter) d of the coal sample projection area is used to represent the particle size characteristic parameters of the coal sample particles, and the coal sample projection roundness F is used to represent the morphology characteristic parameters of the coal sample particles.

[0056]

[0057]

[0058] Where d is the equivalent diameter of a sphere, S is the projected area of ​​the particle, π is the circumference of a circle, F is the roundness, and L is the projected circumference of the particle.

[0059] Step 3. Carry out adsorption test on coal sample and load it into adsorption and desorption determination system. Figure 3 The adsorption-desorption measurement system includes a sample pool 1 and a reference tank 2 connected by an air pipe 3, and the air pipe 3 is connected to an external pipeline at one end close to the reference tank 2 and is provided with a second valve 5. A first valve 4 is provided on the air pipe 3 between the sample pool 1 and the reference tank 2. A pressure gauge 6 is also provided on the air pipe 1 between the first valve 4 and the second valve 5, and the pressure gauge 6 is directly connected to the reference tank 2. After the coal sample is loaded into the adsorption-desorption measurement system, gas sealing verification, high-temperature degassing, free space correction, and adsorption to equilibrium are carried out, and the gas adsorption amount of the coal sample is calculated.

[0060] Specifically, the gas tightness verification is to put the coal sample into the sample cell 1 in the adsorption and desorption measurement system and seal it. After sealing, the entire adsorption and desorption measurement system is kept in a constant temperature environment. Helium gas of a specified pressure is filled into the end of the gas pipe 3 close to the reference tank 2 to test the pressure drop rate of the helium gas, thereby verifying the gas tightness. After completing the gas tightness test of the system, the coal sample is vacuumed and degassed. The free space is corrected and the volume V is increased. r The reference tank 2 is filled with a pressure of P r Then close the second valve 5 and open the first valve 4. When the pressure of the sample pool 1 and the reference tank 2 reaches equilibrium, record the pressure P at this time. t , the free space volume Vf is obtained by pressure change f In this example, when the system is at low pressure and the reference tank and the sample cell have the same temperature, the calculation can be done simply using the following formula:

[0061]

[0062] Similarly, when calculating the adsorption capacity by the volumetric method, since the coal sample has adsorption properties to the gas charged, such as gas, when the first valve 4 is closed, the reference tank 2 is charged with a pressure of P r After the gas is discharged, close the second valve 5, open the first valve 4, and record the pressure P changing with time. t (t), which gradually decreases due to the adsorption of coal samples, and the amount of gas that decreases is the gas adsorption amount Q of the coal sample before crushing ad (), then:

[0063]

[0064] Where R is the gas constant, T is the temperature, K;

[0065] Step 4. Crush the coal sample and measure the desorption. Crush the coal sample containing gas and measure the gas desorption amount during the crushing process. de In the process, it is assumed that the gas pressure of the reference tank 2 before the measurement is P r0 、The gas pressure of sample cell 1 is P t0 After opening the first valve 4, the pressure in the adsorption-desorption measurement system changes with time to Under low pressure desorption and constant temperature environment,

[0066]

[0067] Step 5. Statistics of the particle size and morphology of the coal sample after crushing. The particle size and shape of the coal sample after crushing are statistically analyzed and compared with the particle size and shape of the coal sample before crushing to obtain the changes in the particle size and morphology parameters before and after crushing. The statistical method of the coal sample particle size and morphology characteristics in this step is similar to the statistical method of the coal sample particle size and morphology characteristics in step 2. The parameters Ro of the coal sample particle size and morphology characteristics before and after crushing are calculated and analyzed respectively. The d before and after crushing are used. 50 The degree of change of the index represents the particle size characteristic change parameter.

[0068]

[0069] Where, d 50 The particle size value corresponding to the cumulative distribution percentage reaching 50% is represented by a and b, respectively, after pulverization and before pulverization. In this example, the roundness F of the coal sample is used to describe the morphology of the coal sample, and the following is obtained:

[0070]

[0071] Step 6. First analyze the sensitivity of gas desorption to changes in particle characteristic parameters, and measure the adsorption amount Q during the experiment. ad () and gas desorption amount Q during crushing process de (), and the ratio of desorption amount to adsorption amount Q o Characterize the degree of desorption during the crushing process:

[0072]

[0073] And according to the ratio Mo of the gas desorption degree and the characteristic change parameters of each parameter, the sensitivity of crushing to desorption is analyzed, and the characteristic change parameters representing the crushing process are determined according to the sensitivity. According to step 5, the change of coal sample particle size before and after crushing is measured, and its characteristic changes are statistically analyzed.

[0074]

[0075]

[0076] The particle characteristic parameters are determined through sensitivity analysis. When Mo[]>Mo[], the spherical equivalent diameter d is selected as the characterization value of the coal sample particle size during the coal sample crushing process; when Mo[]<Mo[], the coal sample roundness F is selected as the characterization value of the coal sample particle size during the coal sample crushing process.

[0077] Step 7. Analyze and calculate the desorption law characterization during the crushing process. In this embodiment, when Mo[]>Mo[], the spherical equivalent diameter d is selected as the characterization value of the coal sample particle size during the coal sample crushing process, and the crushing degree Ro[] corresponding to the particle characteristic parameters and the desorption kinetic data Q of the gas-containing coal are used. de () represents the gas desorption law.

[0078]

[0079] The q is a parameter characterizing the gas desorption law during the crushing process of gas-containing coal.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for characterizing gas desorption law during the crushing process of gas-containing coal, characterized in that: The following steps are involved: Step 1. Coal sample pretreatment: clean and dry the coal sample to remove impurities on the surface of the coal sample; Step 2. Statistics of particle size and morphology characteristics of coal samples before crushing: Measure and count the particle size characteristics and morphology of the coal samples, and obtain characteristic parameters of the particle size and morphology of the coal samples before crushing; Step 3. Coal sample adsorption test: measure the gas adsorption capacity of the coal sample before crushing; Step 4. Coal sample crushing and desorption test: crush the coal sample and measure the gas desorption amount of the coal sample during the crushing process; Step 5. Statistics of particle size and morphology characteristics of the coal sample after pulverization: The particle size characteristics and morphology of the coal sample after pulverization are measured and statistically analyzed to obtain characteristic parameters of the particle size and morphology of the coal sample after pulverization, and the characteristic parameters are analyzed and compared with the particle size and morphology of the coal sample before pulverization to obtain characteristic change parameters used to represent the degree of change of the particle size characteristics and morphology characteristics of the coal sample before and after pulverization; Step 6. Analysis of the sensitivity of desorption degree to coal sample particle size and morphological characteristics: Based on step 5, characteristic change parameters representing the degree of change in particle size or morphological characteristics of the coal sample before and after crushing are obtained. The correlation between the gas desorption degree and the characteristic change parameters of the coal sample particle size and the correlation between the gas desorption degree and the morphological change parameters are analyzed and compared to screen out characteristic change parameters for characterizing the gas desorption degree; Step 7. Characterization of the desorption amount during the coal sample crushing process: The desorption amount measured during the coal sample crushing process obtained in step 4 is combined with the characteristic change parameters obtained by analysis in step 6 to obtain a method for characterizing the gas desorption amount during the coal sample crushing process; Wherein, in step 2 and step 5, the particle size of the coal sample is characterized by one parameter selected from the group consisting of triaxial diameter, projection diameter, or spherical equivalent diameter, and the morphology of the coal sample is characterized by one parameter selected from the group consisting of sphericity, roundness, aspect ratio, convexity, angularity index, or roughness; When the coal sample particle size is measured using the spherical equivalent diameter As a characteristic parameter, Where S is the projected area of ​​the coal sample, is pi; The morphology of the coal sample uses roundness F as a characteristic parameter. Where S is the projected area of ​​the coal sample, L is the projected perimeter of the coal sample, is pi; In step 5, the particle size and morphology characteristics of the coal sample before and after crushing are statistically analyzed using the same characterization parameters. The characteristic change parameter representing the degree of change in particle size or morphology of the coal sample before and after crushing is ; in, 、 are the characteristic parameters of the particle size or morphology of the coal sample before and after crushing, 、 When is the characteristic parameter of the particle size of the coal sample before and after crushing, is the particle size characteristic variation parameter, 、 When is the characteristic parameter of the coal sample morphology before and after crushing, is the morphological feature change parameter; Determine the gas adsorption capacity of coal samples before crushing and gas desorption during coal sample crushing , and adopt and Ratio Characterize the degree of desorption during the crushing process: And according to and Ratio The size of represents the analysis of the desorption sensitivity of the crushing process to the desorption degree, and the characteristic change parameter representing the crushing process is determined according to the size of the desorption sensitivity. ; wherein They are and , Where, It represents the particle size at which the cumulative distribution of particles is 50%, and the subscripts a and b represent the coal sample before and after crushing, respectively; described They are and , when the > hour, When the < hour, described It is a parameter that characterizes the gas desorption law during the crushing process of gas-containing coal.

2. The method for characterizing gas desorption law during the crushing process of gas-containing coal according to claim 1, characterized in that: In step 1, the coal sample is cleaned by gas jet cleaning, and cleaning and drying are performed alternately.

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