Precessing jet burners for stable and low NOx pulverised fuel flames - preliminary results from small-scale trials

A new technique for stabilising pulverised coal flames for rotary kilns was demonstrated at 150 kW scale in a model kiln using a burner consisting of a central precessing air jet nozzle and an outer annular coal transport channel. Effective flame stabilisation was achieved by the influence of the precessing air jet on particle trajectories resulting in a reduction in ignition distance by a factor of three compared to a mono-channel burner. A corresponding reduction in CO emissions from 810 to 190 ppm (0% O2 basis) and an increase in carbon burnout from 84 to 92% were achieved without any increase in NOx emissions, which were in the region of 85-100 ppm (0% O2). © 1998 Elsevier Science Ltd. All rights reserved