Combustion behaviors and flame structure of methane/coal dust hybrid in a vertical rectangle chamber

Methane/coal dust hybrid flame propagating in a vertical rectangle chamber was examined experimentally. In these experiments, the coal dusts were dispersed into the chamber by premixed methane/air mixture flow to form a methane/coal dust/air hybrid and the hybrid was ignited by an electrode spark. A high-speed video camera was used to record the images of the propagating flame, and a photodiode was used to study the emitting light characteristics of the flame. Micro-thermocouples and ion current probes were used to obtain temperature profiles and reaction behaviors of the combustion zone, respectively. Based on experimental results, combustion behaviors and flame structure of methane/coal dust hybrid propagating flame were analyzed. After the methane/coal dust hybrid is ignited by the electrode spark, the flame begins to propagate in the chamber. The flame front propagates downwards in the initial 20ms, and then propagates upwards. The flame emits strong yellow light and the luminous zone length increases during propagation. The measured temperature starts to increase at a position about 2.15cm ahead of the reaction zone, then to a maximum value near the end of the reaction zone and then subsequently decreases. The chemical reaction begins while the temperature is about 200 degrees C, and the reaction intensity increases quickly with the temperature increasing. The reaction intensity increases to the maximum value while the temperature is about 500 degrees C and then decreases gradually. According to the measured temperature and ion current curves, the preheated zone of the methane/coal dust hybrid is about 2.15cm in width.