A method for evaluating the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face

Abstract

The present invention belongs to the technical field of coal mine dust removal. It relates to a method for evaluating the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face. By calculating the dust reduction index B and the air control and dust removal effect E under different air control and dust removal process conditions and parameters, the dust reduction effect is evaluated by comparing the values of the dust reduction index B, and the overall air control and dust removal effect is evaluated by comparing the values of the air control and dust removal effect E. In the present invention, quantitative indicators are used to evaluate the air control and dust removal effect. Based on different roadway cross-sections and different process parameters, by establishing the flow field uniformity index and the dust reduction index, the overall dust reduction effect in the roadway is comprehensively evaluated, providing a more comprehensive evaluation method for comparing the advantages and disadvantages of the long-pressure and short-extraction systems under different process conditions and parameters, and providing a basis for judging whether the selection of parameters of the long-pressure and short-extraction systems under different process conditions is reasonable.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine dust removal, and relates to an evaluation method for the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face. Background Art

[0002] In recent years, with the continuous improvement of coal mine tunneling technology and mechanization level, the dust pollution problem in the fully-mechanized heading face has become increasingly serious, threatening the physical and mental health of workers. Long-pressure and short-extraction ventilation dust removal is one of the most effective dust prevention measures in the fully-mechanized heading face, which includes equipment such as a compressed air duct, an attached-wall duct, a dust extraction duct, and a dust collector. The compressed air duct is generally suspended on the roof on one side of the roadway. The attached-wall duct is connected to the compressed air duct and is generally located at the outlet of the compressed air duct. The dust extraction duct is generally fixed above the roadheader body and the second-conveyor bridge, and the tail is connected to the dust collector. Due to its economic and efficient characteristics, it is widely used in the fully-mechanized coal mine heading face. Due to different roadway cross-section sizes and long-pressure and short-extraction process parameters, the dust control and removal effects are also very different.

[0003] When evaluating the dust removal effect of long-pressure and short-extraction air control, the dust reduction efficiency at a certain point or several position points of the roadheader driver is usually used as the evaluation basis, which cannot directly reflect the uniformity of the controlled air flow field, nor can it reflect the influence of air control on dust migration. In the area of the fully-mechanized heading face at a certain distance from the heading face, workers at different positions will be harmed by dust to different degrees. To further reduce dust hazards, it is necessary to establish a more scientific and reasonable evaluation method according to the controlled air flow field and dust migration law of the fully-mechanized heading face, combined with two indicators of air control and dust removal, so as to comprehensively reflect the overall dust control and removal effect with a macroscopic evaluation index. Summary of the Invention

[0004] In view of this, the purpose of the invention is to solve the limitation problem of the existing evaluation method for the dust removal effect of long-pressure and short-extraction air control, and to propose an evaluation method for the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face, so as to more comprehensively evaluate the overall dust control and removal effect of the long-pressure and short-extraction system under different roadway cross-sections and different process parameters.

[0005] To achieve the above purpose, the invention provides the following technical solutions:

[0006] An evaluation method for the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face, by calculating the dust reduction index B and the dust control and removal effect E under different air control and dust removal process conditions, evaluating the dust reduction effect by comparing the dust reduction index B values, and evaluating the overall dust control and removal effect by comparing the dust control and removal effect E values; the calculation of the dust reduction index B and the dust control and removal effect E includes the following steps:

[0007] S1. Determine the roadway range and the number of cross-sections for evaluation: Select roadway cross-sections i1, i2, i3... i at different distances from the heading face n ; where the cross-section in The distance L to the head, and the length of the dust removal system is , and L is 1 to 2 times that of

[0008] S2. Measure the wind speed distribution and dust concentration at each section;

[0009] S3. Calculate the flow field uniformity index A according to the wind speed distribution combined with the flow field uniformity coefficient; calculate the dust reduction index B according to the dust concentration combined with the weight coefficient;

[0010] S4. Calculate the dust control effect E based on the flow field uniformity index A and the dust reduction index B.

[0011] Furthermore, in step S2, the section is evenly divided into j rectangular blocks, the wind speed measurement points are arranged at the center positions of each rectangular block, and the section average wind speed is calculated by using the section multi-point arithmetic mean method;

[0012] Section average wind speed is calculated according to the following formula:

[0013]

[0014] where is the velocity perpendicular to the section direction at each measurement point;

[0015] In step S3, the flow field uniformity coefficient of the section is calculated according to the standard deviation of at each measurement point of this section;

[0016] The standard deviation reflects the degree of dispersion of the wind speed at each measurement point from the average wind speed and is used to measure the uniformity of the wind speed;

[0017] The flow field uniformity index A is calculated according to the following formula:

[0018]

[0019] where , ··· are the average wind speeds of sections , ···, , ··· are the flow field uniformity coefficients of sections , ···.

[0020] Furthermore, the dust concentration measurement points are also arranged at the center positions of each rectangular block, and the section multi-point arithmetic mean method is also used, and the average dust concentration is calculated. The average dust concentration of the section is calculated according to the following formula:​

[0021]

[0022] Among them, c is the dust concentration at each measurement point of this cross-section.

[0023] Optionally, in step S2, when measuring the dust concentration, the single-point method can also be used. The dust concentration at one point is taken for each cross-section. The dust measurement points are arranged on the pedestrian side of the roadway and are not less than 0.5 m away from the roadway sidewall and at a height of 1.4 - 1.7 m from the floor.

[0024] Furthermore, the dust reduction index B is calculated according to the following formula:

[0025]

[0026] Among them, 、 ··· are the average dust concentrations of cross-sections 、 ···.

[0027] Furthermore, the dust control and removal effect E is calculated according to the following formula:

[0028]

[0029] Among them, , is the weight of the flow field uniformity index, and its value ranges from 0.3 to 0.5; is the weight of the dust reduction index, and its value ranges from 0.5 to 0.7.

[0030] Furthermore, the cross-section is evenly divided into j rectangular blocks, ; where m takes a positive integer.

[0031] Furthermore, the distance between each roadway cross-section is 5 - 10 m.

[0032] The beneficial effects of the present invention are as follows:

[0033] The method in the present invention uses quantitative indicators to evaluate the air control and dust removal effects. Based on different roadway cross-sections and different process parameters, by establishing the flow field uniformity index and the dust reduction index, the overall dust reduction effect in the roadway is comprehensively evaluated, providing a more comprehensive evaluation method for comparing the effects of the long-pressure and short-extraction systems under different process conditions and parameters, and providing a basis for judging whether the selection of each parameter of the long-pressure and short-extraction systems under different process conditions is reasonable.

[0034] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. Brief Description of the Drawings

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0036] Figure 1 It is a schematic diagram of the roadway section layout in the present invention;

[0037] Figure 2 It is a schematic diagram of the distribution of section measurement points in the section multi-point arithmetic mean method;

[0038] Figure 3 It is a layout diagram of dust measurement points in the single-point method.

[0039] Reference numerals: 1 - full-section heading machine; 2 - dust extraction air duct; 3 - dust collector; 4 - compressed air air duct; 5 - wall-attached air duct. Detailed Embodiments

[0040] The following illustrates the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0041] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, rather than physical diagrams, and cannot be understood as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, which does not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0042] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0043] Please refer to Figures 1 to 3 , which is a method for evaluating the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized tunneling face. By calculating the dust reduction index B and the air control and dust removal effect E under different air control and dust removal process conditions, the dust reduction effect is evaluated by comparing the values of the dust reduction index B, and the overall air control and dust removal effect is evaluated by comparing the values of the air control and dust removal effect E; the calculation of the dust reduction index B and the air control and dust removal effect E includes the following steps:

[0044] S1. Determine the roadway range and the number of cross-sections for evaluation: Select roadway cross-sections i1, i2, i3 ··· i at different distances from the heading face n ; among them, the distance L from cross-section i n to the heading face, and the length of the dust removal system is , L is 1 to 2 times; among them, the cross-section is evenly divided into j rectangular blocks, ; where m is a positive integer, and the distance between each roadway cross-section is 5 to 10 m.

[0045] In this embodiment, as Figure 1 shown, the long-pressure and short-extraction dust removal system includes equipment such as a compressed air duct 4, an attached wall air duct 5, a dust extraction duct 2, and a dust collector 3. The compressed air duct 4 is generally suspended on the roof on one side of the roadway. The attached wall air duct 5 is connected to the compressed air duct 4 and is located at the air outlet position of the compressed air duct 4. The dust extraction duct 2 is fixed above the body of the fully-mechanized tunneling machine 1, and the tail is connected to the dust collector 3. Among them, the length l of the long-pressure and short-extraction dust removal system is 25 m, L is taken as 50 m, and a total of 7 cross-sections are taken, which are the cross-sections at the driver's position, 5 m behind the driver, 10 m behind the driver, 15 m behind the driver, 25 m behind the driver, 35 m behind the driver, and 45 m behind the driver in sequence; and each cross-section is evenly divided into 16 rectangular blocks. As Figure 2 shown, the center position of each rectangular block is the measurement point;

[0046] S2. Test the wind speed distribution and dust concentration of each cross-section: Divide the cross-section evenly into j rectangular blocks, arrange the wind speed measurement points at the center positions of each rectangular block, and use the sectional multi-point arithmetic mean method to calculate the sectional average wind speed;

[0047] Average cross-section wind speed It is calculated according to the following formula:

[0048]

[0049] Wherein, is the velocity perpendicular to the cross-section at each measuring point;

[0050] The dust concentration measuring points are also arranged at the center positions of each rectangular block. The arithmetic mean method for multiple points on the cross-section is also adopted, and the average dust concentration is calculated. The average dust concentration of the cross-section is calculated according to the following formula:

[0051]

[0052] Wherein, c is the dust concentration at each measuring point of this cross-section.

[0053] In addition, when measuring the dust concentration, the single-point method can also be adopted. The dust concentration of one point is taken for each cross-section. As Figure 3 shown, the dust measuring points are arranged on the side where pedestrians walk in the roadway, and are not less than 0.5 m away from the roadway side and at a height of 1.4 - 1.7 m from the floor.

[0054] S3. Calculate the flow field uniformity index A according to the wind speed distribution in combination with the flow field uniformity coefficient:

[0055] The flow field uniformity coefficient of the cross-section is calculated according to the standard deviation of at each measuring point of this cross-section;

[0056] The standard deviation reflects the dispersion degree of the wind speeds at each measuring point and the average wind speed, and is used to measure the wind speed uniformity. The flow field uniformity index A is calculated according to the following formula:

[0057]

[0058] Wherein, , ··· are the average wind speeds of the cross-section , ···, , ··· are the flow field uniformity coefficients of the cross-section , ···.

[0059] Calculate the dust reduction index B according to the dust concentration in combination with the weight coefficient. The dust reduction index B is calculated according to the following formula:

[0060]

[0061] ​Among them, , ··· are the average dust concentrations of cross-sections , ···.

[0062] S4. The dust control and removal effect E is calculated based on the flow field uniformity index A and the dust settling index B. The dust control and removal effect E is calculated according to the following formula:

[0063]

[0064] Among them, , is the weight of the flow field uniformity index, and its value ranges from 0.3 to 0.5; is the weight of the dust settling index, and its value ranges from 0.5 to 0.7.

[0065] In this embodiment, the dust control and air removal effects under two different process parameter conditions are compared and evaluated. Specifically, the process parameter Ι is: the roadway cross-section width × height is 6m × 4m, the air intake volume of the compressed air duct is 400m 3 / min, the air extraction volume of the dust collector is 600m 3 / min, the ratio of the diameter-axis air volume of the attached wall air duct is 0.75, the distance from the attached wall air duct to the heading face is 10m, the length of the attached wall air duct is 8m, the distance from the dust extraction port of the dust extraction air duct to the heading face is 2m, and the length of the dust removal system is 25m;

[0066] The process parameter II is: the roadway cross-section width × height is 4.8m × 3.1m, the air intake volume of the compressed air duct is 450m 3 / min, the air extraction volume of the dust collector is 400m 3 / min, the ratio of the diameter-axis air volume of the attached wall air duct is 1.0, the distance from the attached wall air duct to the heading face is 10m, the length of the attached wall air duct is 3m, the distance from the dust extraction port of the dust extraction air duct to the heading face is 3m, and the length of the dust removal system is 25m.

[0067] The method in this embodiment is used to measure the wind speed and dust concentration respectively, and calculate the dust settling index B and the dust control and removal effect E. Among them, the wind speed measurement data and calculation results are shown in Table 1:

[0068] Table 1

[0069]

[0070] As can be seen from Table 1, the flow field uniformity indexes A1 and A2 in the two cases of process parameters 1 and 2 are 0.33 and 4.96 respectively, A1 < A2, and the flow field uniformity under the condition of process parameter Ι is better than that of process parameter II.

[0071] The dust concentration and the dust settling index are shown in Table 2:

[0072] Table 2

[0073]

[0074] As can be seen from Table 2, the dust reduction indices B1 and B2 in the two cases of process parameters I and II are 265.3 and 388.0 respectively, B1 < B2, and the dust reduction effect of process parameter I is better than that of process parameter II.

[0075] During the calculation of the dust control effect E, take , , and substitute it into the calculation to obtain:

[0076] E1 = 0.3×0.33 + 0.7×265.3 = 185.8;

[0077] E2 = 0.3×4.69 + 0.7×388.0 = 273.0;

[0078] And E1 < E2, indicating that the overall dust control effect of process parameter I is better than that of process parameter II.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for evaluating the dust removal effect of long-pressure and short-extraction air control in a fully-mechanized heading face, characterized in that: By calculating the dust reduction index B and the dust control and removal effect E under different process conditions and parameters of different air control and dust removal, comparing the dust reduction index B value to evaluate the dust reduction effect, and comparing the dust control and removal effect E value to evaluate the overall air control and dust removal effect; among them, the determination of the dust reduction index B and the dust control and removal effect E includes the following steps: S1. Determine the roadway range and the number of cross-sections for evaluation: Select roadway cross-sections i1, i2, i3 ··· i at different distances from the heading face. n Among them, for cross-section i n , the distance L from the cross-section to the heading face, and the length of the dust removal system is , where L is 1 to 2 times of S2. Measure the wind speed distribution and dust concentration of each section; evenly divide the section into j rectangular blocks, arrange the wind speed measurement points at the center positions of each rectangular block, and use the sectional multi-point arithmetic mean method to calculate the sectional average wind speed; Cross-sectional average wind speed It is calculated according to the following formula: Among them, is the velocity perpendicular to the cross-section direction at each measuring point; The dust concentration measurement points are also arranged at the center positions of each rectangular block. The multi-point arithmetic mean method for the cross-section is also adopted, and the average dust concentration is calculated. The average dust concentration of the cross-section is calculated according to the following formula: Among them, c is the dust concentration of each measurement point of this section; S3. Calculate the flow field uniformity index A according to the wind speed distribution combined with the flow field uniformity coefficient; calculate the dust reduction index B according to the dust concentration combined with the weight coefficient; Flow field uniformity coefficient of the cross-section According to the standard deviation at each measuring point of this cross-section for calculation; The flow field uniformity index A is calculated according to the following formula: Among them, , ··· are the average wind speeds of cross-sections , ···; , ··· are the flow field uniformity coefficients of cross-sections , ···. The dust reduction index B is calculated according to the following formula: Among them, , ··· are the average dust concentrations of the cross-sections , ···; S4. Calculate the dust control and removal effect E based on the flow field uniformity index A and the dust reduction index B; the dust control and removal effect E is calculated according to the following formula: Among them, , is the weight of the flow field uniformity index, and its value ranges from 0.3 to 0.5; is the weight of the dust removal index, and its value ranges from 0.5 to 0.

7.

2. The evaluation method for the long-pressure and short-extraction air control and dust removal effect in the fully-mechanized heading face according to claim 1, wherein: In step S2, when measuring the dust concentration, the single-point method is used, and the dust concentration of one point is taken for each section. The dust measurement point is arranged on the side where pedestrians pass in the roadway, and is not less than 0.5 m away from the roadway side and at a height of 1.4 - 1.7 m from the floor.

3. The evaluation method for the dust removal effect of long-pressure and short-extraction air control in the fully-mechanized heading face according to claim 1, wherein: The cross-section is evenly divided into j rectangular blocks, ; where m is a positive integer.

4. The evaluation method for the long-pressure and short-extraction air control and dust removal effect in the fully-mechanized heading face according to claim 1, wherein: The distance between the cross-sections of each roadway is 5 - 10 m.

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