Searching for dependent air currents in a mine ventilation network using the connected graph disconnection method

Ventilation networks in underground hard coal and copper ore mines are usually designed with branches with dependent air currents. Among these, branches connecting sub-networks of main fans may be distinguished. In view of ventilation hazards: fire hazard, gas hazard, thermal hazard and coal dust explosion hazard, the presence of dependent air-currents may be both desirable and adverse. Information regarding the possible presence and character of the dependent air currents in the mining plant's ventilation network is thus significant. The paper presents a method, based on graph theory, allowing to determine the presence of dependent air currents and their affiliation with the supplied (fresh) air or the removed (used) air. This allows to obtain information whether air currents connecting the main fan sub-networks exist in a ventilation network. The method is applicable in all ventilation networks under the condition of the previous reduction of parallel connections. The paper presents an example of a ventilation network with three main fans, where the method in concern was applied. The algorithm presented in the article allowed to determine the existence of dependent currents in each of the air zones. Additionally, it allowed to identify the main ventilator sub-networks that are interconnected.