Studies On Combustion Techology Of Multi-staging Central-fuel-rich Swirl Coal Combustion Burner Burning Low-volatile Coal

With the improvement of citizens’ quality, more and more people pay attention tothe whole world environment issues. Even through our nation has many kinds of coals,there are still many problems when the power plant boiler is running, owing to the raggedquality of coals. It is difficult to keep stable stratification combustion and often causesmore emission. Consequently, more and more new technique has been adopted. Based onthis situation, this thesis is conducted on the central-fuel-rich swirl coal combustionburner which is burning with the low-volatile coal. In this study, a cold state test schemewas designed, and researched on the cold aerodynamic field in the exit flow field ofburner with different burner geometry. Then this thesis also analyzed combustioncharacteristic and NO_x pollution of the No.11boiler in Guotai Power Co., Ltd throughsome industrial tests.The ribbon tracer method was used to study the characteristics of the coldaerodynamic field at the nozzle zone of burner in different cases, while the blade angleand flaring length of the inner secondary air was changing. Besides, this thesis had testedthe burning condition when the blade angle of the inner and outer secondary air was25°and64°. The diameter of the recirculation region was largest while the flaring distance ofthe secondary air was88.2mm with the same operation condition above, which was themost appropriate mode for burning.Some hot state experiments have been accomplished on a1025t/h power stationboiler which is equipped with twenty-four central-fuel-rich swirl coal combustion burnerin three storeys while burning with the low-volatile coal. Specifically, the componentsand quality of smoke around combustion nozzle and the NO_x emission of the airpreheater outlet had been analyzed with different load conditions, secondary air and thevalve-position of over-fire air while burning. It has been certificated that the averageexhausting quantity of NO_x around the air preheater outlet is877mg/m3（O₂＝6%） andthe boiler efficiency is89.21%while the valves of secondary air and over-fire air openscompletely with the load of300MW. These tests indicate that the comprehensiveindicators of this boiler can satisfy the needs of industrial production well. Nevertheless,while the opening degree of the secondary air middle and lower layer baffle is60%and100%and the valve of over-fire completely opens completely, the generalperformance of the boiler is better with the average exhausting quantity of NO_x aroundthe air preheater outlet is750mg/m3（O₂＝6%） and the boiler efficiency is88.87%withthe load of230MW. Central-fuel-rich swirl coal combustion burner can significantly reduce NO_xemissions, and it can improve the efficiency of the boiler.