Experimental investigation of lean premixed swirl burner

The possibility of improving lean stability and reduction of emission level of the combustion system is explored experimentally extensively in the present work. The present experiment is conducted using a coflow premixed swirl burner at atmospheric pressure using liquefied petroleum gaseous (LPG) fuel. The effects of swirl numbers (0.13 & 0.67) on the lean stability and emission levels are studied for two different coflow cases. It has been found that there is an improvement of the stability limit and CO emission level for high swirl number (0.67) case as compared to low swirl number (0.13). On the contrary, the NO emission level is enhanced considerably with increase of swirl number particularly for higher coflow velocity, which may be due to the higher temperature prevailing in the burner. An attempt is also made to use air-fuel premixed mixture instead of air in the coflow stream. For lower coflow velocity, the stability and CO emission level for low swirl number show an improvement due to presence of improved fuel distribution. In contrast, the CO emission level is increased in the case of low swirl number with higher coflow velocity (Vcf= 2.56). In the case of low swirl number, the NO emission level is improved particularly at high core flow velocity with addition of fuel-air mixture to the coflow. But, the NO emission level does not display any significant change at high swirl number. However, there is a reduction of CO emission level with increasing coflow velocity at high swirl number.