Establishing a low-NOx and high-burnout performance in a large-scale, deep-air-staging laboratory furnace fired by a heavy-oil swirl burner

摘要

A combustion configuration consisting of a low-NOx heavy-oil swirl burner along with overfire air (OFA) and flue gas recirculation (FGR), was developed for the low-NOx heavy oil combustion in a lab-scale furnace. Combustion experiments were performed with various heavy-oil supply temperatures, different oil spray nozzle types, and with or without feeding FGR. The combustion configuration was found to achieve low NOx and acceptable CO emissions (levels of 240-286 mg/m(3) and 45-175 mg/m(3) at 3% O-2, respectively), even under the conditions without FGR. Increasing the FGR ratio from 0 to 10% attained a NOx reduction of 9% without an obvious increase in CO emission. In the oil atomizing nozzle type aspect, a radial bias pattern, which was designed to lower NOx emissions and improve ignition by regulating fuel bias combustion, actually resulted in higher NOx and CO emissions than those using a uniformly atomizing pattern. Decreasing the heavy-oil supply temperature (from 154 degrees C to 132 degrees C) prolonged the fuel combustion process and reduced NOx emissions. Finally, the optimized operation with low NOx and CO emissions (240 mg/m(3) and 45 mg/m(3) at 3% O-2, respectively) was established. (C) 2015 Elsevier Ltd. All rights reserved.