Combustion and emission characteristics for various swirler geometries and fuel heating values in a premixed low swirl combustor system

This study investigated combustion and emission characteristics with various swirler parameters (i.e., swirl angle and perforated screen blockage) and fuel heating values (4,000 kcal/Nm³∼9,560 kcal/Nm³, 16.3 MJ/kg∼55.5 MJ/kg in SI unit) using the premixed low swirl combustor system. Flashback limits were evaluated as a flame stability and flame structures were analyzed by acquiring chemiluminescence (OH* and CH*) and OH-Planar Laser Induced Fluorescence (PLIF) signals. NOx and CO emissions were evaluated by calculating emission indices (EINOx and EICO). As a result, the swirl angle did not affect flame stability, whereas screen blockage increased flashback limits. The highest screen blockage (β = 0.8) showed the flashback limit of 5.6 kW, around 1.5 times higher than the lowest screen blockage (β = 0.6). Also, the blockage affected the radical distributed position due to the ratio between swirling and non-swirling flow. The lower heating value fuel showed reduced flashback limits, decreased radical intensities, and lower emissions (EINOx and EICO). The lowest heating value gas (HV 4000) had an EINOx of less than 0.5 g/kg and an EICO of less than 5 g/kg, respectively. In conclusion, these findings would be helpful databases for optimizing heating values to solve environmental pollution issues.