Numerical Simulation and Optimization of "Non-Catalytic Reduction" Process for Circulating Fluidized Bed Boiler Based on Properties of Materials

Abstract:

The selective non-catalytic reduction (SNCR) process of a 480tžh^-1 CFB boiler was simulated with the Reynolds Stress Model (RSM) model. The effects of injection position, normalized stoichiometric ratio (NSR) and reaction temperature on the NO_x removal process were studied with urea and ammonia as reducing agents. While three spray guns were set at the outside of the separator entrance and two spray guns at the up side, the system can reach the highest NO_x removal efficiency. The NO_x reduction efficiency of ammonia is about 20%-25% higher than that of urea, but the ammonia slip is also higher. The NO_x reduction efficiency and ammonia slip both increases with the increase of NSR. Raising the inlet gas temperature of cyclone separator can significantly improve the NO_x removal efficiency and reduce ammonia slip. At the temperature of 925 C, the ammonia slip of the two reducing agents are both less than 10μl/l. Simulation results are comparatively consistent with the experiment datas cited form authoritative journals.

• Periodical: Advanced Materials Research (Volume 886)
• Pages: 45-50
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.886.45
• Online since: January 2014
• Authors: Wen Yan Li, Yan Kong*, Li Tan, Zhi Xiang Sun
• Keywords: Ammonia Slip, Circulating Fluidized Bed, NO_X Removal Efficiency, Simulation, SNCR

References

[1] ZHOU Xing-long, Research on the hydrodynamics and heat transfer in a 600MW CFB boiler furnace[D] ．Hangzhou: Zhejiang University, (2010).

[2] LIU Shu-yan, ZHANG Ya, WANG Bao-guo, Cyclone Separator Three-Dimensional Turbulent Flow-Field Simulation Using the Reynolds Stress Model[J]. Transactions of Beijing Institute of Technology．2005, 25(5): 377-383.

[3] Aoki H, Fujiwara T, Morozumi Y, et al．Measurement of urea thermal decomposition reaction rate for NO selective non-catalytic reduction[C]/Fifth International Conference on Technologies and Combustion for a Clean Environment . Lisbon, Portugal, 1999 : 115-118.

[4] Nguyen T D B, Lim Y, Kim S, et al．Experiment and computational fluid dynamics (CFD)simulation of urea-based selective non-catalytic reduction (SNCR) in a pilot-scale flow reactor[J]．Energy & Fuels, 2008, 22(6) : 3864-3876.

DOI: 10.1021/ef8004652

[5] LI Ke-fu, WU Shao-hua, LI Zhen-zhong, et al．Pilot-scale Experimental Study of NOxOUT Process [J]. Proceedings of the CSEE, 2006, 26(25): 97-101.

[6] Lü Hong-kun. Experimental and mechanism study on selective non-catalytic reduction and advanced reburning [D]. Hangzhou：Zhejiang University, (2009).

[7] LIANG Xiu-jin, ZHONG Zhao-ping. Simulation of Selective Non-catalytic Reduction Process by the Model of Laminar Finite Rate With FLUNT [J], Proceedings of the CSEE, 2009, 29 (35): 96-101.