Local fan discharge gas
Gas discharge when the excavation work faces the wind
1. Winding cylinder method: Before starting the bureau fan, first tie the air duct in front of the bureau fan, leaving only the small hole, start the local fan, and supply the wind to the working surface. The gas moves outwards in the laneway as a whole. It is diluted into the full wind pressure, and the size of the air duct is determined by the amount of gas. Finish the gas and open the air duct.
2. Blocking fan method: Before the starter fan, use the wooden board or belt to block the upper part of the fan, then start the local fan, determine the size of the block according to the gas condition, and wait until the gas is exhausted to remove the baffle or belt.
3. Set the three-pronged air duct gas: set a three-fork air duct in front of the local fan, one fork supplies air to the working surface, and the other fork is normally ventilated when the fork is not allowed to leak air. When it is necessary to open the gas, the three forks are opened, and then The bureau fan is activated, and a part of the fresh air is supplied to the working face. A part of the fresh air comes out at the trigeminal and directly enters the return airway. The wind flow in the working face is also to push the gas in the roadway to the full wind pressure and then dilute it. According to the gas condition, the air volume at the trigeminal is controlled until the gas is exhausted and the air is tight.
4. Disconnect the air cylinder method: Before starting the local fan, the gas ventilator checks the gas in the direction of the working face. When the gas concentration reaches 1%, the air cylinder is disconnected, and the local fan is directly activated. The air cylinder is half according to the gas concentration. Docking, one person checks the gas at a distance of 5 meters to 10 meters behind the air duct. The concentration is not allowed to exceed 1.5%. When it is over, the air tube is removed, and more fresh air. When the concentration drops, the air tube is more than the upper point. Children, so repeated until the gas is not over, all connected to the air duct.
Compare these four methods of exhaust gas: the advantages of the first three methods are simple and easy. Its principle is to reduce the supply of wind to the working face, the gas as a whole goes outward, and the gas is diluted to the full wind. Disadvantages: First, the supply of air is small, and the gas moves slowly. If a roadway is a few hundred meters or the kilometer is too long. Second, it is difficult to master the high-concentration gas at the full wind pressure. It is necessary to check the gas frequently, and people are easily exposed to high-concentration gas. The third is when the gas is discharged, the wind is too large and it is a wind. The fourth is to adjust the air volume is near the local fan, the noise is large, the connection is inconvenient.
The advantage of the fourth method is that the gas is diluted by all the local fan air, the discharge time is short, the gas concentration is easy to control, the human does not touch the high concentration gas, and the high concentration gas is only in the high gas area. The disadvantage is that the air duct needs to be disconnected, and then the local fan is activated outside. In case of sudden power failure, the personnel should immediately withdraw the tunnel. It is safer to withdraw people because the outside gas is below 1.5%.
The first three methods have many disadvantages. If the full wind pressure returning to the air duct is steep uphill or standing, it is very difficult to check the gas. The fourth method has strong adaptability. Generally, the roadway is excavated. If there is no special gas emission point, the gas emission time of the outer roadway is long, the gas emission is reduced, and the gas is gradually extended from the working surface to the over-limit area. With the broken air tube method, the gas can be quickly discharged, the time for gas accumulation is reduced, and the normal ventilation is quickly restored.
If the gas emission from the roadway is particularly large, the gas in the entire roadway is over-limit, and the gas concentration must be controlled at the full wind pressure. Special measures should be taken when starting the fan. The fan collector can be blocked by a belt or a wooden board, and the belt or wood board can be gradually removed according to the gas condition after the fan is started. This method is suitable for the operation of gas drainage with a large wind pressure and large wind supply. In 1991 a new coal mine excavation team 003 West Main transportation construction two-level roadway, section 16㎡, three 28KW wind for local fan for air volume 840m3 / min, maximum gas emission amounted to 10 m3 / min. (At that time, there was no gas drainage work). The wind-stop gas was over-limit, and the concentration of 500 m to 600 m was over 3%. The working face is to open up the roadway, and the return air enters the production level into the wind. The air volume at the full wind pressure is more than 6000 m3/min, which is to use this method to discharge the gas. 005 digs two 28KW bureau fans to supply air, several power outages and winds over the gas limit, also use this method to exhaust gas.
Some mines use the method of intermittently stopping the fan to discharge gas. This is the most unfavorable method and the danger is very large. Hair Dryers iron wire hanging due to open a large fan-duct shake strength, hairdryer rings with wire friction sparks hit easily, inducing gas.
Gas discharge in front of the front roadway (long-term non-ventilated roadway discharge)
Before the roadway runs through, the gas in the other lane must be discharged. There are several situations:
1. There is a duct in the roadway: If it is a single lane, and there is a set of ducts in the lane, such as the upper lane in place, the downhill is not in place, and the upper lane is closed when considering the need to exhaust gas. The downtime is not long. The air duct in the closed area of ​​the upper lane can not be removed, and there is no need to reset the air duct when discharging gas. After the airtightness is closed, the air duct is first sealed. The air supply to the single head should be determined according to the gas concentration. When the gas concentration is less than 1.5% at the full wind pressure of 10 meters, the air duct is connected to the air. Then, the gas is discharged as in the above-mentioned broken air cylinder method.
2. There is no air duct in the roadway:
When there is no air duct in the roadway, it is necessary to connect one section from the outside to the inside. Each time the air duct of the air duct is to be blown for a while, to ensure that the gas inside the air duct is not more than 1.5% within 10 meters, and then the next full section of the air duct is laid. Open, but also slow docking, the latter one to check the gas (method same as before) If the gas concentration of the roadway is particularly high, you can prepare a half-meter 5 meter long air duct, and the whole section of the 10 meter long wind tube is connected backwards. Pay attention to the gas in the roadway along the empty roadway. Because the gas in the goaf is constantly pouring out, every time a wind tube is connected, the gas concentration can not drop below the specified concentration for several tens of minutes. Do not rush to connect the air duct, causing the return air gas. Overrun). Until the entire lane of gas is discharged.
3. Breaking the closed gas:
Breaking tool must be sealed copper brazing copper hammer, typically by a rescue team construction, check before the gas sealed closed prior to the break, the first open hole may be observed if the observation hole, check the gas, if not directly broken overrun closed. In the case where there is no observing hole and the closed inner gas is not known, the local fan and the air duct must be set before breaking the airtight, the local fan is started, and the closed fan is blown, and the small hole of not more than 10 cm in diameter is broken by the copper brazing, and the gas condition is observed. If the gas pressure is large when the hole is broken, it is not allowed to ream the hole. It must wait until the pressure disappears and no longer spray the gas and re-expand the hole. At the same time, check the gas concentration of the return air. If the gas concentration drops below 1% after the gas concentration drops below 1%. Continue to break the airtightness, and then use the above-mentioned roadway without the air duct to discharge the gas.
For safety reasons, the personnel should be closed and the miner's lamp can be removed when the conditions permit. Others should give illumination at the full wind pressure (the general condition is not more than 5 meters at the full wind pressure) to prevent the mine lamp from detonating when the gas concentration reaches the explosion limit. Detonate the gas.
Full wind pressure gas
Full-air pressure-discharge gas refers to the use of the main fan to exhaust the gas, and the closed roadway that has formed the wind path, such as the alternate mining face or the roadway that is reasonably idle for the ventilation system, needs to discharge the gas in the roadway before returning to normal ventilation.
The full-air pressure-discharged gas should adhere to the principle of first breaking the wind-side sealing, and then breaking into the wind-side sealing. The method of breaking the airtightness is the same as above. In order to accurately control the gas flow, when the wind is closed, the area can be broken, and then the board, the belt or the bricks are first plugged, and after the air inlet side is closed, according to the gas condition, on the return air side. Gradually open the bricks or planks to enter the return air duct gas concentration is not exceeded, until all the gas is exhausted.
Slow emission methods are sometimes used. Time is allowed in the roadway that does not need to restore ventilation immediately, and the air-tight closed observation hole is opened in advance to make the gas slowly release for a long time. As long as the fence is set at the full wind pressure on the return air side, a special person is guarded to prevent high contact. Concentration gas can be used. Some closed inner gas is larger, after a few days of release, when the gas is broken, the gas has dropped below the safe concentration. This method is often used in actual production processes.
Preparation of gas emission regulations
Regardless of which gas venting method is used, it is necessary to prepare an exhaust gas operation procedure and report it to the technical person in charge for approval. The preparation of the procedures shall be prepared by the ventilation area or the technician of the mining area. The regulations shall have construction instructions, the length of the gas discharged, the estimated gas emissions, and the situation of the gas emission area and the wind flow. All exhaust gas lanes must be powered off, evacuated, clear the person responsible for the power outage and the switch required for power outage. All the passages leading to the gas roadway and the return roadway are set to be vigilant. It is strictly forbidden for the unrelated personnel to enter the roadway through which the gas is returned to the exhaust gas. The ventilation system diagram of the gas drainage area shall be drawn, and the warning position shall be marked on the map.
The procedure should clearly stipulate the discharge of the gas commander and the person in charge of the alert. The alert personnel are not notified, they are not allowed to leave the alert position, who is the security guard, who ordered the withdrawal. Every time the gas is checked, it is determined that the working surface gas is not overrun. Gas can not ignore the gas accumulation in the local high-top, there is a local wind accumulation plate, or use the air duct to remove the gas.
Every gas-fired personnel, security personnel, and electricians who participate in the gas exhaustion must listen to the technician's implementation of the approved discharge regulations and sign.
In summary, the discharge of gas is a relatively dangerous job, but as long as we strictly follow the rules, it is safe to discharge gas.
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