Scaling and development of low-swirl burners for low-emission furnaces and boilers

• Published in: Proceedings of the Combustion Institute 2000, Vol.28 (1), p.1305-1313
• Main Authors: Cheng, R.K., Yegian, D.T., Miyasato, M.M., Samuelsen, G.S., Benson, C.E., Pellizzari, R., Loftus, P.
• Format: Article
• Language: English
• ISSN: 1540-7489; 1873-2704
• DOI: 10.1016/S0082-0784(00)80344-6

A low-swirl burner (LSB) developed for laboratory research has been scaled to the thermal input levels of a small industrial burner. The purpose was to demonstrate its viability for commercial and industrial furnaces and boilers. The original 5.28 cm i.d. LSB using an air-jet swirler was scaled to 10.26 cm i.d. and investigated up to a firing rate of Q=586 kW. The experiments were performed in water heater and furnace simulators. Subsequently, two LSBs (5.28 and 7.68 cm i.d.) configured to accept a novel vaneswirler design were evaluated up to Q=73 kW and 280 kW, respectively. The larger vane-LSB was/studied in a boiler simulator. The results show that a constant velocity criterion is valid for scaling the burner diameter to accept higher thermal inputs. However, the swirl number needed for stable operation should be scaled independently using a constant residence time criterion. NO x emissions from all the LSBs were found to be independent of thermal input and were only a function of the equivalence ratio. However, emissions of CO and unburned hydrocarbons were strongly coupled to the combustion chamber size and can be extremely high at low thermal inputs. The emissions from a large vane-LSB were very encouraging. Between 210 and 280 kW and 0.8