How to classify the ventilation methods during roadway excavation, what are the advantages and disadvantages of each?

The tunneling ventilation mode can be divided into three types: press-in type, draw-out type and hybrid type.
Press-in ventilation: The local fan blows fresh air into the working surface through the air cylinder, and the dirty air flows out along the roadway. During the ventilation process, the gun smoke is gradually discharged with the wind. When the concentration of the gun at the exit of the roadway drops to the allowable concentration, it is considered that the exhausting process is over and the personnel can enter the working surface. Press-in ventilation has a large fresh air flow, short ventilation time and good effect, but it is easy to cause sewage circulation. Therefore, the local fan must be installed in the roadway through which fresh air flows, and the distance from the roadway of the roadway should not be less than 10m.
Withdraw ventilation: fresh air enters the working surface from the roadway, and the dirty air is pumped out through the air duct and discharged into the return airway. The advantages and disadvantages of extractive ventilation are the opposite of the push-in type. The exhaust vent of the air duct must be located below the main roadway in the direction of wind flow, and the distance from the roadway of the roadway should not be less than 10m.
Hybrid ventilation: Hybrid ventilation is a combination of press-in and extractive ventilation, and has the advantages of the first two ventilation modes, suitable for ventilation under long road conditions.


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