Influence Of Arrangement Of Tertiary Air And The Low NOx Combustion Characteristic Of A 300MW Storage Tangential Boiler

The storage tangential boiler generally adopts exhaust gas tertiary air and hot air feeding system, which is usually applied to low-volatile lean coal, this results the higher emission of NOx and high difficulty in low NOx burner transformation. In this paper, a certain storage tangential boiler was studied. Numerical calculation was applied to simulate the operation condition of the boiler and the simulation result was compared with the experimental data. Besides, five setting patterns for the tertiary air were investigated in order to find out the distinct influence of different patterns on the combustion and NOx emission characteristics inside the boiler.Firstly, we compared the working condition data of the prototype boiler before and after optimization, and the numerical simulation was conducted to vindicate the correctness of the operating modeling. Then, the objective boiler 's low-NOx burner was properly redesigned and five arrangement form of tertiary air was proposed on the basic of the characteristics of exhaust gas. The combustion characteristics and the rehabilitation programs under different arrangements were investigated. The simulation indicated that when the tertiary air in the E zone transferred to the zone of BC1, the NOx emission level was lower and lower with the decreasing speed of the tertiary wind of E zone and the NOx emission was less than that inside the optimized boiler. When the tertiary air in the E zone transferred under the bottom wind, the NOx emission was decreased to some extent compared to that of the boiler after optimization. When the tertiary air was transferred to the upper zone, the NOx emission level was lower. The key parameters should be taken into consideration in a reasonable and economic level after transformation.In the end, the paper simulated the retrofit effects at different speed of primary air and secondary air after low NOx burner transformation and analyzed the low-NOx combustion characteristics of the operation mode of tertiary air under different load. The results proved that the larger the secondary air speed, the lower the NOx emission. What is more, the increase of the primary air led to the rise of the NOx emission, While, decreasing the amount of operating mill could reduce the NOx emission. The result is instructive for the future optimization and research of low NOx burner for storage tangential boiler.