Mechanical activation of micronized coal: Prospects for new combustion applications

The paper presents experimental studies of the effects of enhanced mechanical activation of microground coal on its inflammability and combustion efficiency. Experimental test of reactivity of pulverized coal milled in a new rotating impact disintegrator developed at the IT SB RAS (Novosibirsk, Russia) showed that the coal activation threshold was reduced by a factor of two or more, making it easier to ignite and burn more efficiently. The preliminary experiment in a pilot-scale 1 MW rig, followed by more detailed experimental and numerical investigations in a cylindrical swirl combustor of 5 MW thermal power, confirmed the earlier visual observations and measurements that the mechanically disintegrated micro-ground coal behaves much like heavy oil. This offers prospects for designing new coal-dust burner that will ensure ignition at much lower temperatures, more efficient and more stable combustion and lower NOx emission compared with coal of the same granulation (about 40 μm) obtained in conventional mills. The research offers new opportunities for replacing liquid fuels by coal in various combustion applications for heating and electricity production from coal as well as new prospects for efficient coal gasification.