Investigation of the effect of the precessing jet nozzle in the combustion of pulverised coal

Abstract

The effect of the Precessing Jet flow-field on the coal burnout, gas species concentrations (CO, NO, SO2, N2O) and gas temperature of a pulverised coal flame was investigated. Two burner arrangements were used with a central Precessing Jet nozzle for air or gas supply inside an annulus for coal delivery. Four flames were examined of heat input of 110-140 kW. The flames were compared with 110 kW flames from the literature. It was deduced that the Precessing Jet nozzle can be used to make a monochannel flame approach the profiles of coal burnout, concentration of CO and gas temperature of a swirl-stabilised flame, without the need for swirling the secondary air and quarl application. Furthermore, the flue gas emissions of NO did not exceed 43% of the levels expected for a swirl-stabilised coal flame of similar thermal load, while the emissions of N2O were negligible.