Abstract: Water and coal cinder in the downward drainage holes influence the effect of gas drainage. A new method is proposed to drain water and coal cinder by jets. A set of device for drain water and cinder by jets is designed. The feasibility of this method is verified by using orthogonal test and the influences of working parameters on the device performance are also researched. The results show that the device performance is most affected by compressed air pressure p. The amount of water and coal cinder increase at first and then reduce as p increases indicates that there exists an optimal air pressure p* making the device performances the best. There is a critical depth Hnp of drainage holes. When the depth of hole is less than Hnp, the amount of water and coal cinder keep invariant. However, the amount decreases gradually when the depth of hole is more than Hnp. If all other conditions do not change, the amount of water and coal cinder increase gradually as the water depth in the holes increase. The p* of the device for water and coal cinder drainage is 0.55 MPa obtained by experiments. The method of draining water and coal cinder by jets is feasible and simple to operate and available to drain water and coal cinder effectively in the drainage holes of coal mine.

Key words: gas drainage hole, water and coal cinder drainage, experimental study