CN201902228U - Automatic regulation and control early warning system for underground gas extraction pipeline concentration - Google Patents

Abstract

The underground gas drainage pipeline concentration automatic regulation and early warning system is equipped with a signal acquisition unit and an execution unit on the gas drainage pipeline, wherein the signal acquisition unit is connected to the input end of the control unit, and the execution unit is connected to the output end of the control unit; the signal The acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the execution unit is composed of electric valves. The utility model scientifically and automatically regulates the gas extraction concentration of the pipeline, improves and stabilizes the gas extraction concentration in the pipeline, and satisfies the needs of gas utilization and pipeline safety within a certain range. The pipeline safety mentioned here refers to: adjust the concentration of gas drainage to be beyond the explosion limit as much as possible, in addition, give an early warning of the spontaneous combustion of the coal body in the borehole caused by the gas leakage in the borehole and the sudden drop in the concentration caused by the damage of the pipeline. When the negative pressure in the extraction pipeline suddenly drops or suddenly changes to positive pressure, close the valve quickly.

Description

Automatic control and early warning system for underground gas drainage pipeline concentration

technical field

The utility model relates to the technical field of gas drainage in coal mines, in particular to a method for regulating gas concentration in an underground gas drainage pipeline and a hidden danger early warning method.

Background technique

In the past ten years, my country's coal output has increased from 1 billion tons to 3 billion tons, and the mining depth has increased year by year. There are more and more high-gas mines and coal and gas outburst mines. The state stipulates that gas drainage must be implemented in high-gas mines and coal and gas outburst mines, and mining is not allowed if the drainage does not meet the standards. Underground gas drainage is one of the main means of coal mine gas control. It is an important safety guarantee for high output and high efficiency in high outburst mines, and it is also the basis and premise of gas utilization.

Underground coal mine gas drainage by borehole drilling usually involves constructing a large number of boreholes into the coal seam, then sealing and connecting the holes, and finally connecting them to the drainage pipeline in the roadway. The vast majority of coal seams in my country are low-permeability coal seams, and gas drainage is difficult, and there are relatively serious gas leakage in sealing holes and gas leakage in joint holes, which have not been solved yet. After the drilling hole leaks, the overall concentration of gas drainage will decrease. If the gas concentration in the drainage pipeline is within the explosion limit (methane content of 5%-16%), it will bring safety problems to the drainage pipeline. There have been cases in China where gas explosions led to explosions in drainage pipelines, which magnified the accident.

If the gas extraction concentration is too low to reach the usable concentration, the low concentration gas will be forced to be discharged into the atmosphere, which not only increases the emission of greenhouse gases, but also wastes energy resources. In the early Ruhr mining area abroad, for the purpose of gas utilization and pipeline safety, the drainage pipeline was shut down and started regularly in order to obtain a safe and usable gas concentration. In some domestic mining areas, in order to increase the concentration of pipeline drainage, they basically rely on closing holes. If any drilling concentration is found to be low, it will be closed without analysis. Sometimes a drilling hole leaks through the drainage system of the entire roadway. To deal with it will cause great waste, fail to eliminate the sudden effect, and also leave a safety hazard for future coal mining.

Although the above method can increase the concentration of gas drainage to a certain extent, the gas is not fully released due to the closed holes, which not only reduces the efficiency of resource utilization but also leaves a safety hazard for coal mining. At the same time, this part of the gas is directly discharged into the atmosphere. It will aggravate the greenhouse effect and pollute the atmospheric environment.

In short, due to the gas leakage problem in drilling and sealing, and the difference in drilling depth, the change of coal seam permeability and the difference in sealing quality, the gas drainage concentration of drilling in this coal seam has the following problems:

1. The gas concentration control is not considered as a whole from the coal seam's own conditions, gas permeability, gas content, gas pressure and other combination points;

2. The drainage concentration of different boreholes in the same area varies from high to low, while the rate of decay of gas concentration varies from fast to slow, with large differences;

3. How much negative pressure should be used for extraction depends entirely on experience. There is no specific concentration control theory and application method for guidance, which is too one-sided and sloppy.

Utility model content

The key technical problem to be solved by the utility model is to change the current situation of manual adjustment and blind regulation of the gas concentration in the existing gas drainage pipeline, and to solve the matching problem between the negative pressure of the gas drainage pipeline and the gas concentration and flow rate; the purpose is to provide An automatic control and early warning system for the concentration of an underground gas drainage pipeline and a use method thereof, which improve and stabilize the gas concentration in the drainage pipeline, and implement early warning of hidden dangers in the drainage pipeline.

In order to achieve the above object, the utility model adopts the following technical solutions:

The automatic regulation and early warning method for the concentration of an underground gas drainage pipeline comprises the following steps:

①. Assemble the signal acquisition unit and the execution unit into one, and install it on the gas drainage pipeline; the signal acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the described The execution unit is composed of electric valves;

②. Operate the execution unit to determine the longest negative pressure lag time and the highest pipeline gas concentration between pipeline gas concentration and drainage negative pressure, so as to obtain the change curve of pipeline gas concentration and drainage negative pressure;

③. According to the obtained longest negative pressure lag time and the highest pipeline gas concentration, set the early warning gas concentration and early warning negative pressure lag time; the set value of the early warning gas concentration is lower than the maximum pipeline gas concentration value, and the high The minimum value required for gas drainage; the warning negative pressure lag time is 1.5 to 2 times the longest negative pressure lag time;

④. Collect the current gas concentration value and negative pressure value in real time; if the current gas concentration value is greater than the maximum pipeline gas concentration, it will prompt that the maximum pipeline gas concentration is wrong, and re-execute step ②; if the current gas concentration value is lower than the maximum pipeline gas concentration concentration, but greater than the pre-alarm gas concentration set value, keep the electric valve opening unchanged; if the current gas concentration value is Continue to extract gas under negative pressure;

⑤. After the system is running normally, repeat steps ②～④ regularly.

The pipeline negative pressure sensor, gas concentration sensor, carbon monoxide sensor and pipeline flow tester of the signal acquisition unit are integrated and installed in one section of pipeline, and this section of pipeline is installed on the side with lower negative pressure of the electric valve device.

In the above step ②, the determination of the longest negative pressure lag time is to close the opening of the electric valve from above 90% to below 10%, and at the same time inject a small amount of carbon monoxide at the end of the pipeline and start timing. The timing ends when the adjacent carbon monoxide sensor detects CO.

In step ②, by closing the electric valve at an angle of 1%~5% each time, after waiting for the longest negative pressure lag time, record the pipeline concentration value and pipeline negative pressure value, and repeat this process to obtain the pipeline gas concentration The graph of the variation curve with the negative pressure of drainage, so as to determine the negative pressure corresponding to the highest pipeline gas concentration.

In the above step ④, the step of searching for the optimal negative pressure for drainage is: fully open the electric valve, wait for the lag time, record the initial concentration value C0, negative pressure value P0 and flow value Q0, and close the electric valve for 1 %~5% angle, wait for the lag time to read the new concentration value Ci, negative pressure value Pi and flow value Qi (i=1, 2, 3...n), record the current electric valve opening Ki; when the electric valve Stop the valve closing operation when the opening Ki>=99%, and find the maximum concentration value Cmax from the concentration value Ci (i=0, 1, 2, 3...n), and then judge whether the negative pressure corresponding to Cmax is unique, If it is unique, the electric valve opening Ki corresponding to the maximum value Cmax is sent to the electric valve device, and if not unique, the valve opening Ki when the negative pressure is high is sent to the electric valve device.

In the underground gas drainage pipeline concentration automatic regulation and early warning system implementing the above method, a signal acquisition unit and an execution unit are arranged on the gas drainage pipeline, wherein the signal acquisition unit is connected to the input end of the control unit, and the execution unit is connected to the output end of the control unit; The signal acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the execution unit is composed of an electric valve.

The pipeline negative pressure sensor, gas concentration sensor, carbon monoxide sensor and pipeline flow tester in the signal acquisition unit are integrated and installed in a section of pipeline, and this section of pipeline is installed on the side with lower negative pressure of the electric valve device .

The utility model adopts the above-mentioned technical scheme, aims at the coal seam conditions in different mining areas, studies the interchanging relationship between the extraction concentration and the extraction negative pressure at different extraction stages, and proposes an automatic control and early warning system for the concentration of underground gas extraction pipelines The gas extraction concentration of the pipeline is scientifically and automatically regulated to improve and stabilize the gas drainage concentration in the pipeline, and meet the needs of gas utilization and pipeline safety within a certain range. The pipeline safety mentioned here refers to: adjust the concentration of gas drainage to be beyond the explosion limit as much as possible, in addition, give an early warning of the spontaneous combustion of the coal body in the borehole caused by the gas leakage in the borehole and the sudden drop in the concentration caused by the damage of the pipeline. When the negative pressure in the extraction pipeline suddenly drops or suddenly changes to positive pressure, close the valve quickly.

Description of drawings

Fig. 1 is a functional block diagram of the utility model.

Fig. 2 is a structural diagram of the utility model.

Fig. 3 is a flow chart of the control and early warning program in the utility model.

Fig. 4 is a flow chart of the optimal drainage negative pressure search program in the utility model.

Fig. 5 is a flow chart of the curve drawing program in the utility model.

Figure 6 is a graph showing the relationship between the initial drainage borehole concentration and negative pressure.

Fig. 7 is a graph showing the relationship between concentration and negative pressure in boreholes in the later stage of drainage.

Detailed ways

Before designing the utility model, the following analysis and research were done: the relationship between the concentration of gas drainage and the negative pressure of gas drainage in different extraction stages is changing, and the requirements for the level of negative pressure are different in different stages. Use negative pressure. As shown in Figure 6, excessively high negative pressure at the initial stage of drainage will lead to a decrease in drainage concentration, and too low negative pressure in the middle period of drainage will also lead to a decrease in drainage concentration. Relationship, as shown in Figure 7, if the negative pressure is too high or too low, the extraction concentration will decrease, and there will be a peak extraction concentration. Based on the above findings, the utility model can automatically adjust the pipeline drainage negative pressure at different drainage stages, stabilize the gas drainage concentration, and provide early warning for pipeline abnormalities.

In the utility model, the automatic regulation and early warning method for the concentration of the underground gas drainage pipeline includes the following steps:

①. Assemble the signal acquisition unit and execution unit into one, and install it on the gas drainage pipeline; the above-mentioned signal acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the above-mentioned execution unit Includes valves and electric valve devices. Better, the pipeline negative pressure sensor, gas concentration sensor, carbon monoxide sensor and pipeline flow tester of the signal acquisition unit can be integrated and installed in a section of pipeline, and this section of pipeline can be installed in the electric valve device with low negative pressure. side.

②. Operate the execution unit to determine the longest negative pressure lag time and the highest pipeline gas concentration between pipeline gas concentration and drainage negative pressure, so as to obtain the change curve of pipeline gas concentration and drainage negative pressure.

The above-mentioned maximum negative pressure lag time is determined as follows: Since the gas drainage pipeline is very long, after the electric valve for adjusting the negative pressure is activated, the gas concentration in the pipeline will change, and finally reach a new concentration value. This process requires The time is the longest negative pressure lag time.

In the actual measurement, the determination of the longest negative pressure lag time is to close the electric valve opening from more than 90% to less than 10%, and at the same time inject a small amount of carbon monoxide at the end of the pipeline and start timing. When the carbon monoxide sensor next to the valve Timing ends when CO is detected. It should be noted that the opening of the electric valve is fixed at two openings. After the concentration is stable at 90% opening, close the valve to less than 10% and inject CO at the same time. When CO diffuses to the sensor, it can be considered that at this time The concentration in the pipeline is uniform. The recorded time is actually the time it takes for CO to diffuse from the end of the line to where the sensor is located.

The above-mentioned maximum pipeline gas concentration is determined as follows: the above-mentioned process of determining the longest negative pressure lag time is executed multiple times, and each process increases the negative pressure by closing the valve at a certain angle, and a set of concentrations can be obtained. And the corresponding curve of negative pressure, this is the change curve of pipeline gas concentration and drainage negative pressure. When the negative pressure increases to a certain level, the concentration in the pipeline will no longer rise, and sometimes it will drop instead. This is because the airtightness of the pipeline is not good enough, and the increase of negative pressure leads to an increase in the amount of air leakage in the pipeline, which in turn reduces the gas concentration in the pipeline. When the curve is determined, the negative pressure corresponding to the highest pipeline gas concentration is determined. During the specific implementation, by closing the valve at any angle of 1%, 2%, 3%, 4%, and 5% each time, after waiting for the longest negative pressure lag time, record the pipeline concentration value and pipeline negative pressure value, and repeat this process The change curve graph of pipeline gas concentration and drainage negative pressure can be obtained.

③. According to the obtained longest negative pressure lag time and the highest pipeline gas concentration, set the early warning gas concentration and early warning negative pressure lag time; the above-mentioned early warning gas concentration setting value is lower than the maximum pipeline gas The minimum value required for gas drainage; the warning negative pressure lag time is 1.5 to 2 times the longest negative pressure lag time.

The setting value of early warning gas concentration is set according to the requirements of mines. Different coal mines have different setting values. Some require the gas concentration to reach 30%, and some require 25%. Others are only 5%. The gas with such a concentration on the ground can be used for power generation, heat supply, etc., and can also be stored. If the concentration is too low, it will be directly discharged into the atmosphere. The two parameters of early warning gas concentration and early warning negative pressure lag time are set to ensure that the gas concentration extracted from the gas pipeline meets the ground use conditions. When the gas concentration in the pipeline does not reach the set early warning gas concentration, the Call the police. The setting of the early warning negative pressure lag time is to ensure that the gas concentration in the pipeline is uniform and stable, so that the alarm will not be issued in advance when the concentration is not uniform.

④. Collect the current gas concentration value and negative pressure value in real time; if the current gas concentration value is greater than the maximum pipeline gas concentration, it will prompt that the maximum pipeline gas concentration is wrong, and re-execute step ②; if the current gas concentration value is lower than the maximum pipeline gas concentration concentration, but greater than the pre-alarm gas concentration set value, keep the valve opening unchanged; if the current gas concentration value is Gas extraction continues on negative pressure.

In the above step ④, the steps to search for the optimal extraction negative pressure are: fully open the valve, wait for the lag time, record the initial concentration value C0, negative pressure value 0 and flow value Q0, and close the electric valve by 1%~ 5% angle, wait for the lag time to read the new concentration value Ci, negative pressure value Pi and flow value Qi (i=1, 2, 3...n), record the current electric valve opening Ki; when the electric valve opening Stop the valve closing operation when Ki＞=99%, and find the maximum concentration value Cmax from the concentration value Ci (i=0, 1, 2, 3...n), and then judge whether the negative pressure corresponding to Cmax is unique, if unique The electric valve opening Ki corresponding to the maximum value Cmax is sent to the electric valve device, and if not unique, the valve opening Ki when the negative pressure is high is sent to the electric valve device.

⑤. After the system is running normally, repeat steps ②～④ regularly. The above-mentioned period means that after the system has been working for one or two years, the downhole pressure, gas concentration and other parameters have changed greatly, and the set concentration, concentration and negative pressure lag time need to be corrected and adjusted again. Adjustment.

The automatic control and early warning system of the underground gas drainage pipeline concentration and its use method of the utility model, firstly, the processing unit judges whether the gas concentration in the gas drainage pipeline is greater than or equal to The set concentration value, if it is greater than the set concentration value, the execution unit will not act, if it is close to or less than the set concentration value, the processing unit will drive the execution unit to act, adjust the gas extraction negative pressure in the pipeline through the valve opening of the execution unit, and follow the procedure The command searches for a reasonable extraction negative pressure. A reasonable extraction negative pressure refers to the negative pressure under which the gas extraction concentration is higher than the set concentration value, and the pure methane flow rate is the largest under this concentration. In addition, when the processing unit receives a carbon monoxide signal, the early warning unit will issue a carbon monoxide alarm; when the processing unit detects a sudden change in the gas concentration, the early warning unit will issue a concentration alarm. The processing unit directly displays the signals obtained by the sensors and testing instruments on the display unit, and the scalar gas extraction per unit time is calculated by the program.

The utility model also provides an automatic regulation and early warning system for the concentration of the underground gas drainage pipeline, which is provided with a signal acquisition unit 4 and an execution unit 1 on the gas drainage pipeline, wherein the signal acquisition unit 4 is connected to the input end of the control unit 3, The execution unit 1 is connected to the output end of the control unit 3, and the above-mentioned control unit 3 is composed of a control cabinet 8 and a programmable controller 7 located in the control cabinet. The above-mentioned signal acquisition unit 4 is a sensor group 6, and the sensor group 6 includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the execution unit includes a valve and an electric valve device.

Preferably, the pipeline negative pressure sensor, gas concentration sensor, carbon monoxide sensor and pipeline flow tester in the signal acquisition unit can be integrated and installed in a section of pipeline, which is located on the main gas drainage pipeline 9, and Install this section of pipeline on the side with lower negative pressure of the electric valve device.

In the above solution, the signal acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor, and a pipeline flow tester, etc., and the signals collected by them are respectively connected to the input terminals of the processing unit. The execution unit is the numerical control electric valve 2, which includes two parts: the valve and the valve electric device. The CNC electric valve receives the control signal from the processing unit, and can perform operations such as full opening, full closing, jog opening, jog closing, etc.; it can precisely adjust the opening of the valve, and feed back the information of the opening of the valve to the processing unit. The control signal of the numerical control electric valve is connected with the output node of the processing unit, and the valve opening signal of the numerical control electric valve is connected with the input node of the processing unit. The processing unit is a programmable controller, and the display unit can be LCD, LED or touch screen.

Claims (2)

1. The underground gas drainage pipeline concentration automatic regulation and early warning system is characterized in that: a signal acquisition unit and an execution unit are set on the gas drainage pipeline, wherein the signal acquisition unit is connected to the input end of the control unit, and the execution unit is connected to the output of the control unit end; the signal acquisition unit includes a pipeline negative pressure sensor, a gas concentration sensor, a carbon monoxide sensor and a pipeline flow tester; the execution unit is composed of an electric valve. 2. The underground gas drainage pipeline concentration automatic regulation and early warning system according to claim 1, characterized in that: the pipeline negative pressure sensor, gas concentration sensor, carbon monoxide sensor and pipeline flow tester in the signal acquisition unit It is integrated and installed in a section of pipeline, and this section of pipeline is installed on the side with lower negative pressure of the electric valve device.

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