Effect of volatile and ash contents on cloud ignition behaviors were examined for pulverized coal dust clouds, that were suspended in a laminar upward flow and heated by a single-pulsed YAG laser. We compared burning times of volatile matter, flame propagation velocities and lean flammability limits for several coals. The coals contains almost same volatile matter, but different ash. The present results showed that the burning time of volatile matter, flame propagation velocity and lean flammability limit were mainly determined by volatile content. The effects of ash content were small. The maximum flame propagation velocity increased with volatile content. The velocity increased the third as much as when volatile content increased from 10% to 20%.
