Modelstudy on dynamics of open fire in underground coal mines under varied air flow

A small scale model representing mine gallery has been designed, constructed and installed at Central Mining Research Institute, Dhanbad, India. The basic purpose of the model gallery was to study the complex phenomenon of open fires in simulated underground mine condition. The model is 19 m long having hvo segments. The first one is 10m long insulated rectangular segment having cross section of 45 cm × 57 cm. Insulation lining of fire bricks leaves space of 13 cm × 13 cm for air flow through the model. The second segment is 9m long, 30 cm diameter, circular section having a centrifugal exhaust fan installed at its end. Two sets of experiments were carried out in the model at air velocities 1.0 m/s and 1.5 m/s using coal blocks of 5 cm thickness lined in all four inner sides of the model. The coal lining was made for a length of 3 m starting from 1 in of the model entry. After establishing the desired airflow inside the model, fire was initiated artificially at the begining of the coal zone. Governing parameters such as gas concentration, temperature, pressure drop across fire zone, air velocity and dust concentration inside the model were continuously monitored for about 8 to 9 hours. The paper highlights the salient features of the model, instrumentation system, experimental procedure, important observations, results of the experiment and correlation of findings with particular reference to gas concentration, temperature and fire size.