Numerical Simulations Of SNCR System In CFB Boiler And Its Application

Nitrogen oxides(NOx), one of the main gaseous pollutants, have received lots of research attentions. Several NOx emmison control technologies have been developed and comericially applied. Among them, Selective Non-Catalytic Reduction (SNCR) has become one of the promising NOx removal methods due to its short construction period and low investment. As the high requirements of the flow field and gas mixture, numerical simulation becomes the nessesary demands in the SNCR projects application. In this dissertation, the numerical modeling of SNCR System in CFB boiler was systematically investigated. Furthermore, the industrial test was conducted based on the simulation results.Firstly, Computational Fluid Dynamic(CFD) numerical simultations regarding a lab-scale oil-boiler burner have been carried out. Base on the analysis of fluid flow, heat-transfer and combustion reactions, NOx formation during the combustion System and the mixing behaviros of NH3 after injection in the experimental platform were simultated. Moreover, the simultation results of the flow filed, the temperature and NOx distributions on the experiment platform were obtained.Secondly, the flow field, the temperature distribution and SNCR reactions on a 200Nm3/h burning experiment platform was measured. Compared with the simulation results, the temperature deviation is less than 3.5%, and the speed deviation is almost zero. The experimental results verified the veracity of the simulation results.Thirdly, numerical simulation of the flow field on a 75t/h CFB boiler of a paper manufactory was conducted. Through the numiercal analysis, the injector parameters were obtained with ensuring NH3 coverage exceeding 80%. Considering the SNCR reaction under this condition, the NOx removel efficiency was predicted to be over 65%.Finally, the SNCR project of a paper manufactor was constructed through the CFD report. The testing showed that, within the temperature rang of 830～920℃, the NOx removal efficiency was around 65% at a NSR of 1.5, which was in accordance with the simulation results.