An Experimental Study of a Syngas Burner with Low NOx Emission

• Main Authors: Ih-yang Wu, 吳志陽
• Other Authors: Shenq-yang Shy
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/61569047961087945009

碩士 === 國立中央大學 === 機械工程研究所碩士在職專班 === 99 === The basic design concept of weak-swirl-jet burner (WSJB) is coming from Bédat & Cheng (1995). To settle a weak jet swirl generator in advance position, produce a stable diverging flow field at the lower reaches and a bowl-shaped premixed turbulent flame. Then, this generator is made by 4 tangential weak air jets at 20 degree_inclination. Syngas, a mixture of mainly carbon monoxide (CO) and hydrogen (H2), is an important fuel in Integrated Gasification Combined Cycles. The most of previous studies in the feature of syngas combustion are limited in the laminar flame regime, and it’s scanty of studies to focus on turbulence combustion of syngas. However, utilizing the fast mixing apparatus and the lean turbulent combustion technique developed in our laboratory, we investigated the turbulent burning velocities (ST) and the exhaust emissions of the premixed lean syngas flames in the WSJB at two equivalence ratios of equivalence rate = 0.5 and equivalence rate = 0.7. The syngas used is the product from fluidized bed, with 65% CO and 35% H2. We identified the stable operation regime of the burner. Using particle image velocimetry and a gas analyzer, we measured the turbulent burning velocities and the emissions of NOx and CO under different equivalence ratios, mixture flow rates (characterized by the jet Reynolds number Rej ), and swirl strength (characterized by the swirl number S). The main results from our experiments include: (1) On the (Rej , S) plane, the stable operation region for equivalence rate equivalence rate = 0.7 is broader than that for equivalence rate = 0.5; (2) Increasing the concentration of H2 extends the flammable limits of the syngas and increases the ST ; (3) Both ST and turbulent intensity increase with the increase of Rej ; (4) Turbulent burning velocities normalized by the laminar burning velocity, ST/SL, of the bowl-shaped flames in the WSJB are higher than the turbulent spherical flames under the same conditions; and (5) Over the range of Rej and S explored, the NOx emission is always below 10 ppm, with the minimum below 5 ppm for equivalence rate = 0.5. Our experiment demonstrated that the WSJB is superb burner in terms of reducing NOx emission. Moreover, our study improves to understanding the turbulent flame of syngas feature and practical apply limitation. That benefits the development of Integrated Gasification Combined Cycles (IGCC).