A mine fire model gallery has been designed and constructed on the premises of the Central Mining Research Institute, Dhanbad, India to perform systematic in-depth studies on various aspects of mine fires. The gallery is 65.5 m long and 5.86 m2 in cross-section and it is divided into firing and non-firing zones. It is equipped with a computer-aided online telemonitoring system that has 130 sensors, two data loggers and computer peripherals for continuous recording of various fire parameters. A fan to generate airflow through the gallery has been installed at its end. Two sliding doors and one rolling shutter were also provided for sealing and regulation of airflow.
Two sets of experiments have been carried out in the model gallery maintaining air velocity of 1 and 1.5 m/s through it. In the experiments, the inner sides of the firing zone, 22 m in length, were lined with a thin layer (8–10 cm thick) of coal slabs. Two fire suppression techniques viz. flushing of liquid nitrogen (LN2) and infusion of high pressure high stability (HPHS) nitrogen foam were tried to quantify their effectiveness under dynamic fire conditions.
The paper addresses important design features of the gallery, its instrumentation system, the experimental procedure adopted and important findings from the experiments.
It has been observed that the intensity of the fire was very high after one hour of its initiation and continued for 3–4 hours. During the period, frequent backlash with smoke and flame was noticed. The efficacy of the fire suppression techniques has been assessed in terms of reduction in temperature, generation rate of CO2 and CO, and heat release rate. The study reveals that high pressure high stability (HPHS) nitrogen foam is more effective in controlling open fires than liquid nitrogen is.