Stoppage plan of gas drainage and safety technical

2022-10-01
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According to the arrangement of Shanxi jiaomeihan [2012] No. 372 document "work arrangement on grasping the safety of low concentration gas drainage and transportation" and the notice of hmdtz [2013] No. 10 document "about strengthening the management of gas drainage system", our mine specially formulates the gas drainage shutdown plan and air drainage safety technical measures, The specific plans and measures are formulated as follows:

I. mine gas emission

1. Mine gas grade identification in 2011:

according to the reply on the 2011 mine gas grade identification results of Shanxi Coking Coal Group Co., Ltd. issued by the Department of coal industry of Shanxi Province, the absolute gas emission of our mine is 2.99m3/min, and the relative gas emission is 0.53m3/t, The absolute emission of carbon dioxide is 4.86 m3/min, and the relative emission is 0.85m3/t. The identification result is a low gas mine

2. Current gas emission of mining face:

at present, there is one fully mechanized mining face and seven tunneling faces arranged under the mine. The heading face has one blasting face and six comprehensive excavation faces. At present, the maximum gas concentration of the return air flow in the mining face is 0.1%, the absolute gas emission is 2.1 m3/min, the relative gas emission is 0.304 m3/t, and the maximum gas concentration of the return air flow in the heading face is 0.06%, the maximum absolute gas emission is 0.27 m3/min

3. Gas content in goaf

at present, there are three old goaf areas in our mine, which are goaf of working face, goaf of working face and goaf of working face. The gas concentration in goaf is analyzed according to the test of beam tube monitoring system. The highest gas concentration in goaf of working face is 10.89%, goaf is 5.12% and goaf is 3.57%

4. Gas source analysis

① the working face of our mine adopts the comprehensive mechanized coal mining method of full height mining at one time, and the coal seams are 1#, 2# coal coalbed. Through the detection of gas emission in 20 120 meter deep coal water injection drill holes outside the working face in August 2012, it was found that the gas concentration in the new construction drill holes was up to 27%, and the concentration could be reduced to 0.7% after nearly a week of diffusion. According to this situation, it is preliminarily judged that the gas in the upper corner mainly comes from this coal seam

② after a month's observation in August 2012, it was found that the gas concentration in the upper corner would rise significantly when the shearer was cut to the tail section and the old gob roof of the tail frame of the puller fell, so it can be preliminarily judged that the gas mainly came from this coal seam

II. Basic situation during the operation of the gas drainage system

1. The gas drainage pump station

the gas drainage pump station is set in the rail triple lane of mining area 1. The pump station has an independent ventilation system and is currently equipped with an air volume of 300m3/min

two zwy150/200 mobile gas pumps (one for use and one for standby) are installed in the underground mobile extraction pump station, with the motor power of 200kW and the rated flow of 150m3/min, which are mainly used to discharge the gas in the working face and the goaf of the working face. At the same time, the construction of the pump station has a volume of 20m. These pipes will be placed in a circulating water tank 3 on the sea, equipped with two anti backwater and air return devices, two water seal explosion-proof devices, one negative pressure waterproof device, one positive pressure waterproof device, one slag remover, one orifice flowmeter and one anti backfire device

the pumping station adopts double circuit power supply to ensure that there is always a pumping pump in the hot standby state at all times

2. Drainage method and effect

when the gas drainage system of our mine is used to drain the upper corner of the working face and the old goaf in the early stage, the gas concentration in the pipeline of the pump station is between 5% and 7%, and the gas emission in the upper corner of the working face and the old goaf can be effectively controlled through the gas drainage system

① drainage method and effect analysis of the working face

the working face adopts the upper corner intubation method for gas drainage, and the maximum concentration of drainage is 0.5%. The absolute emission of gas in the front of the work is 1.56 m3/min, and the net amount of gas drainage is 0.65m3/min. After drainage, the gas concentration in the upper corner is stable below 0.3%. In order to further enhance the effect of gas drainage, the next step is to carry out gas pre drainage on the mining face by means of high-level drilling (drill yard) and gas drainage of this coal seam, so as to maximize the efficiency of the drainage system

②. Analysis of the drainage method and effect of the goaf in the working face

the goaf in the working face adopts the fully closed drainage method for gas drainage, and the maximum drainage concentration can reach more than 5%. After closed drainage, the gas concentration in front of the closed wall of the main and auxiliary roadways in the goaf is less than 0.1%. At the same time, the ventilation team is required to manually sample and analyze the concentration of fire gas in the goaf every five days, and take corresponding fire prevention and extinguishing measures immediately if the index exceeds the limit

3. The gas drainage pipeline

is laid to the upper corner of the working face, the goaf and the upper corner of the working face respectively through the return air roadway of the first mining area. The gas drainage pipeline of the working face and the goaf is hung with a 40 # galvanized flat iron processing bracket. The gas drainage pipeline of the return air roadway of the first mining area is hung with a 10 # channel steel processing bracket. The hanging height, anti-skid measures The anti-static measures and the installation of water drainers can be constructed in strict accordance with the requirements of the specification for gas drainage in coal mines (AQ). The total laying of pumping and discharging pipelines is 5020m, and the diameter of main and main pipelines is Φ 280mm special PE gas drainage pipe

4. Measures and management means for slag filtration and slag removal of extraction pipelines at various locations

① a drainage pipeline slag remover is installed in the gas drainage pump station of our mine. It is required to clean up the sundries in the slag remover once a week. At the same time, closely observe the pressure changes in each branch pipe through the U-shaped water column meter. If the pressure is abnormal, immediately check the pipeline and clean up the sundries sucked in by the pipeline

② iron gauze is installed at the suction port of the extraction pipeline to ensure that sundries cannot enter the pipeline during the extraction process

III. mine mobile gas and Ali's data capacity drainage system shutdown plan

1. The goaf of the working face

at present, there is a closed connection in the main roadway of the working face Φ 280mmpe gas drainage pipe, the butterfly valve has been closed to stop drainage. The air distribution volume of the original roadway before the closure of the wall is 900 m3/min, which is currently increased to 1400m3/min. By increasing the air distribution volume, the gas concentration before the closure of the wall is maintained at about 0.2% to ensure that gas does not accumulate before the closure of the wall

2. Upper corner of the working face

at present, the upper corner of the working face is connected once Φ 280mmpe gas drainage pipe adopts intubation drainage method for drainage. At present, the working face is in the stage of support withdrawal. Considering that the roof of the working face withdrawal channel collapses and falls behind during the support withdrawal, the air volume of the working face may be reduced or there may be no wind. In order to ensure that the gas of the working face does not exceed the limit during the withdrawal, the arrangement of not stopping the gas drainage system of the working face during the withdrawal is adopted. Stop the operation of the pumping system after all the supports and equipment of the working face are withdrawn and the sealing conditions are met

3. Upper corner of the working face

at present, the upper corner of the working face is connected once Φ 280mmpe gas drainage pipe was originally planned to be drained by intubation. Considering that the gas concentration in the working face and the upper corner is not more than 0.2% when the air distribution volume of the working face increases to 2200m3/min, the air and gas drainage can basically meet the requirements, so it is decided to stop pumping it

IV. safety technical measures for air and gas drainage

the main purpose of installing mobile gas drainage system in our mine is to solve the problem of gas overrun in the upper corner of the coal mining face. Now, the safety technical measures for air and gas drainage in the upper corner are formulated as follows:

1. Diluting the gas concentration in the upper corner by using the air curtain to guide the air

diluting the gas in the upper corner by using the air curtain to guide the air is the first simple method used. The method is to use an air duct with appropriate size to cover the airflow of the mining face on the windward side of the upper corner, so as to change the flow direction, lead the wind to the upper corner, and blow away the gas accumulated in the upper corner

2. Use the telescopic air duct to guide the air

select a 104.6 m-long telescopic air duct. If the sample is not easy to take out, fix one end of the telescopic air duct in the support channel at the end of the working face, lead one end to the upper corner, and use the telescopic air duct to guide the fresh air flow of the working face to the upper corner of the working face, so as to increase the air volume there, so as to achieve the effect of diluting the gas concentration

3. Air volume and air pressure regulation method

that is to set up regulating air windows in the air return roadway of the working face close to the air return roadway of the servo valve area after mining and cleaning, reasonably allocate the air volume of the working face, and use the air windows to increase part of the air pressure, so that the air pressure and the air resistance and air volume of the working face match the passing capacity of the working face, so as to reduce the excess air volume entering the goaf, reduce the width of the air leakage zone, and increase part of the air pressure, Reduce the emission of gas from coal seams and goaf, so as to reduce the gas concentration

4. Timely retract the column and force caving method

as the working face advances, timely remove the tray and bolts of anchor support near the upper corner, so that the top plate of the upper corner falls with the mining, and is aligned with the working face, so as to minimize the space of the upper and lower corners, cut off the gas channel in the goaf, and change the distribution of air leakage in the goaf

5. Use compressed air pipeline to increase the air flow diffusion coefficient in the gas accumulation area in the upper corner and improve the ability of air flow to disperse locally accumulated gas

use the compressed air pipeline near the upper corner to connect a branch pipe to dilute the locally accumulated gas at the upper corner. Through practical tests, under the existing gas emission conditions, the gas concentration in the upper corner can be effectively controlled below 0.5%. The compressed air pipeline is one of the "three lifelines" responsible for the safety of mine workers. It advances synchronously with the working face for a long time. It is convenient to access and disable the switch, and there is no need to add additional electrical equipment (directly supply to each mining working face from the ground air compressor room). It has high safety and strong adaptability

6. Upper limit air distribution

by adjusting the angle of the main fan blade of the mine, increase the air volume of each air using place in the mine, ensure that all points can distribute air according to the upper limit air distribution principle, and solve the gas problem through air exhaust to the greatest extent

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