Mine ventilation

(2) Mine ventilation equipment

1. Fan classification

At present, there are two kinds of fans used in mine, one is axial fan and the other is centrifugal fan. The axial flow fan is characterized by a straight line between the air inlet direction and the air outlet direction, and is parallel to the axis. When the working wheel keeps rotating, because the blade is an airfoil shape and has a certain Angle with the rotating surface, a low pressure area is generated behind the advancing blade to inhale air, and a high pressure area is generated in front of the advancing blade to press out air. The centrifugal fan is characterized by the air inlet direction and the air outlet direction are perpendicular to each other. When the working wheel rotates in the spiral housing, due to the centrifugal force generated by the blade, the air flows in the housing along the path of the blade movement from the tangential direction of the working wheel. In this way, a low pressure area is generated in the central part of the working wheel to inhale air; The rim creates a high pressure that pushes air out of the diffuser.

Compared with the centrifugal fan, the axial fan has high efficiency and light weight, and the Angle of the driving wheel blade can be adjusted. At present, the metal mine is widely used, but its noise is large and its maintenance is complicated.

The fans used in the mine are divided into the following types according to their uses: the fans used for the ventilation of the whole mine, that is, the main fans; A fan used to enhance the ventilation of a certain section, that is, an auxiliary fan, that is, a fan used for ventilation of a single-head working face, that is, a local fan.

2. Working mode of the fan

The working mode of the fan can be divided into three kinds: pressing type, pulling type, pressing and pulling combined type.

3. Anti-wind device

The main ventilator must have a reverse air device. When the mine fire and mine dust explosion occur, in order to prevent the expansion of disaster and adapt to the requirements of rescue work, sometimes it is necessary to change the direction of mine air flow. The air reflux device is related to the fan type. Figure 3-10 shows the common air reflux device of the axial fan. Lift gate 1 and lower gate 2 on reverse wind.

(3) Mine ventilation structures

Devices used to guide, interrupt and regulate air flow are collectively referred to as ventilation structures.

Ventilation structures can be divided into two categories, one is the structure that passes through the air flow, including wind bridge, wind deflector, wind barrier and regulating wind window; the other is the ventilation structure that interrupts the air flow, including sealing walls and air doors.

1. Wind Bridge

When the inlet air duct and exhaust air duct cross in the ventilation system, in order to separate the fresh air and the dirty air, it is necessary to build a wind bridge. The requirements for the wind bridge are strong, tight, less air leakage, small wind resistance, and the wind speed through the wind bridge should be less than 10m/s.

The wind bridge cut in the upper mine rock at the intersection of the roadway is called the bypass type wind bridge, which has the least air leakage and can pass through a large air volume, and is suitable for the main wind road.

At the intersection of the roadway, concrete wind bridge can be built, it is relatively strong, can be used for the air volume of not more than 20m³/s roadway can also set up simple iron drum wind bridge, iron drum can be made of round or torch shape, iron plate thickness is not less than 5mm, suitable for the air volume of less than 10m³/s in the secondary wind path.

2. Air deflector

The following types of air deflectors are used in mine ventilation.

(1) Air guide plate. In order to prevent air leakage at the bottom of the mine, the air guide plate is installed at the intersection of the air inlet stone door and the stage transportation roadway, and the direction of the wind flow pressure is used to reduce short circuit air leakage. The wind deflector can be made of wood, iron or concrete. The intersection Angle between the air inlet roadway and the transport roadway should be 45°, the roadway Angle and the air deflector should be rounded, and the length of the air deflector should exceed a certain distance (0.5~1m) from the roadway intersection.

(2) reduced resistance wind deflector. In order to reduce the ventilation resistance at the right-angle transition of the roadway with large airflow volume, the airfoil or ordinary curved wind deflector can be made of iron plate to reduce the energy loss of airflow impact. The open Angle of the air deflector at the right corner can be 100°, and the installation Angle can be 45° to 50°. After the installation of the air guide plate, the local resistance coefficient of the right Angle turn can be reduced to 1/4 to 1/3 of the original.

(3) Bus deflector plate. At the fork of the shaft and lane, when the two air currents meet and converge together, a herring-shaped wind deflector can be installed to reduce the impact energy loss when the air currents collide.