Effects of exhaust tube vortex on the in-furnace phenomena in a swirl-stabilized pulverized coal flame

This paper presents an experimental investigation of the effects of the exhaust tube vortex (ETV) on pollutant emissions and carbon burnout performance. The novelty in this study is to improve understanding of combustion behavior with the ETV structure via detailed in-furnace measurements (temperature, gas-phase species concentration, carbon burnout, emissions, and etc.) in a 16-kW(th) coal-fired furnace. The experiment considered two different swirling flames (co- and counter-swirl) with four air staging positions. A hollow tubular structure such as the ETV structure has been created under the co-swirl condition. The values of NOx emissions are about 430 ppm, but the CO emission is lower and carbon burnout is approximately 2% higher than that of the counter-swirl unstaging condition at the furnace outlet. For the air staging conditions, the air staging position 3 (SL3) maintained the generated ETV structure stronger in the primary combustion zone. The SL3 condition produced the lowest CO emission at about 275 ppm, and a relatively low emission of NOx showed with the highest carbon burnout performance of approximately 94.5% or more. The SL3 condition is the most favorable condition for the synergistic effect of air staging technology on the ETV structure with a low-NOx swirl-stabilized burner. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This paper presents an experimental investigation on the effects of the exhaust tube vortex (ETV) on pollutant emissions and carbon burnout performance. The results show that under the co-swirl condition, the ETV structure can reduce CO emissions and improve carbon burnout performance. Among the air staging positions, position 3 maintains the ETV structure in the primary combustion zone better and results in the lowest CO emissions, relatively low NOx emissions, and the highest carbon burnout performance.