Changes of ventilation by a mine fire

摘要

The airflow rate of ventilation changes when a mine fire occurred.The direction of ventilation changes when the airflow rate changes in large extent.The fire gas flows to not only the downwind side but also the upwind side along the roadway ceiling even in a horizontal roadway.As a result,the harmful gas generated by the mine fire might flow to the place where is not anticipated.Therefore,the persons who are doing the extinction work or rescue operations might encounter the harmful gas suddenly,and they suffer.It is necessary to know the changes in ventilation under the mine fire accurately to prevent such a disaster,and to execute the effective extinction measures.In this paper,the changes in ventilation under the actual mine fire are described.Then the results of mine fire experiments carried out to examine the backflow of the fire gas are described.A series of experiments concerning the flow of the fire gas by a small model are carried out.It was shown that the direction of ventilation might be completely reversed in the entire mine by the thermo dynamic effects of the fire.It was also shown that there is a possible high risk even in the upwind side of the fire because the fire gas will flow there after the reversal of the direction of the ventilation air.