What are upward ventilation and downward ventilation?

Upward ventilation and downward ventilation refer to the airflow direction of inclined shafts and inclined lanes (especially coal mining faces). Upward flow means upward ventilation; On the contrary, it is downward ventilation. As far as the coal mining face is concerned, the elevation of the air inlet roadway is lower than that of the return roadway, and the airflow flows upward in the inclined direction, which is called upward ventilation of the working face, and vice versa. Upward ventilation is adopted in most coal mining faces in China, and its main advantage is that the gas discharged from the face is fully diluted and discharged.

Characteristics of reverse ventilation. The characteristic of this ventilation mode is that the airflow direction of the air inlet roadway and the air return roadway in the working face is opposite and parallel. The main advantages of this ventilation mode are that the air leakage rate of goaf is small; Its disadvantage is that the airflow speed is low, and gas is easy to accumulate near the upper corner of the working face, which affects safety production.

Co-ventilation mode. The characteristic of this ventilation mode is that the air inlet roadway and the air return roadway flow in the same direction.

Extended data:

The return air of the working face is discharged from the return air lane of the goaf (gob-side entry retaining) and the boundary of the mining area up the mountain. Its advantage is that the goaf air leakage is used to bring the gas into the airflow of the return air roadway of the working face, so as to prevent the goaf gas from rushing to the working face or accumulating in the upper corner of the working face. But its disadvantage is that there is more air leakage in goaf, which is easy to cause spontaneous combustion.

Ventilation mode of opposite-pulling face. The opposite working face is a ventilation system composed of three roadways, which is divided into two ventilation modes: one in one out and one in one out. Compared with reverse ventilation and co-direction ventilation, this ventilation mode has the advantages of large ventilation volume, small resistance and less air leakage in goaf. But they all have the disadvantage of downward ventilation.