Design And Numerical Simulation Of A New Flue Gas Internal Recirculation Low-NO_x Burner

With the increasing attention of China to pollution control and environmental protection,NOx produced in combustion process have become the focus of the research on combustion pollution emission because of their difficult and harmful characteristics.In this paper,a new type of flue gas internal recirculation low-NOx burner(FIR)is designed and related research is carried out.By combining numerical simulation and experiment,the characteristics of flame combustion and NOx emission of flue gas internal recirculation and blunt body design are investigated.The control variable method and the high precision numerical simulation are used to obtain the data of the flow field in the burner,and the influence of thermal power and swirl angle on the flame characteristics is explored.In addition,the new type of flue gas internal recirculation low-NOx burner is further processed and assembled in the heating furnace.The flame structure in the burner is observed by experiment and the emission of nitrogen oxides is obtained by using the flue gas analyzer.By comparing the experimental measurement results with the numerical simulation results under different thermal power,this paper verifies the accuracy of the numerical simulation and makes a comprehensive analysis of the operation effect of the FIR.The results show that:(1)Low thermal power(10 kW)makes the temperature uniformity in the combustion chamber better,but failing to establish effective swirl effect,and the combustion is unstable while the higher thermal power(30 k W)leads to a longer residence time in the high temperature zone,promotes the generation of thermal type NOx and deteriorates the temperature uniformity in the combustion chamber.(2)The large swirling angle(40°)makes the shear layer affected by reflux and unable to stabilize combustion.When the swirl angle is 35°,the low-NOx emission is lower,but the combustion is unstable.When the swirl angle is 30°,the flame stability is higher and the temperature uniformity in the combustion chamber is better.(3)When the swirl angle of the low nitrogen burner is 30°and the thermal power is 20 k W,the nitrogen oxide emission can be effectively controlled below 50 mg/Nm~3 and the combustion is stable.