Study Of Arrangement Form And Combustion Characteristic Of SOFA On A300MW Tangential Boiler

The air-staged technology, the reburning technology and the low-NOx burner are themain measures used widly to control the NOx emission from the coal-fired power plantsall over the world. This paper focused on the tangentially fired boiler of300MW andanalyzed the impact of the arrangement from of the SOFA (Separated over fire air) on theNOx emission, the adaptation of the coal type and the self-adjustment capacity of thevarying duty. We had fully analyzed the influence of various factors on the combustionand NOx emission and the results was meaningful for research and project.Fristly, the paper used numerical calculation to simulate the operation condition ofthe boiler and compared the result of simulation with the experimental data. Thecomparison proved that the model was reliable. Based on the condition of the boiler andthe actual situation of the scene, we had proposed three projects of the arrangement formof the SOFA. Then we simulated different operation conditions for analyzing the impactof the SOFA wind rate, the excess air coefficient and the pivot angle on the combustionand NOx emission. The result proved that when the SOFA wind rate was about30%, thekey parameter of the three different forms appeared a reasonable level and NOx emissionof boiler met requirements. The relationship between the excess air coefficient and thecondition of the boiler was similar for three differernt forms. The deep air-stagedcombustion of double-section control behaved well for the combustion and burnout of theboiler and could reduce the NOx emission well. That form was more appropriate for thelow-NOx retrofitting of the boiler, because nozzles of SOFA were more flexible for thecontrol method and it was better for the adaptation of the boiler. This paper compared thecondition before the reform with the condititon after the retrofitting, which proved thatthe retrofit project was reliable. Moreover，this paper had analyzed the adaptation of the coal type and the self-adjustment capacity of the varying duty with numerical simulation. The results provedthat the adaptation of the boiler was good for high-ash bituminous coal and low-volatilebituminous coal, but the adaptation for the coal of high calorific value was worse. Theimpact of the coal mill on the combustion and NOx emission was prominent and theexcess air coefficient’s impact on that was not obvious.