| Summary: | A flue gas internal and external double cycle low nitrogen burner was established. Using the method of orthogonal test, the number(n), inclination angle (i) and diameter (d) of the injection pipe, the end deflection angle(γ), overlap angle(β) and number (η) of the blade were set two levels respectively, and the maximum furnace temperature (Tmax), average furnace temperature (Tav) and NO emissions at the furnace outlet (MNO) were taken as experimental indexes. It is found (1) The influence degree of various factors of nozzle structure on the three indexes is n > d > i. The influence degree of cyclone structure factors on the three indexes is γ > β > η. The effects of factors i and η on the three indexes were negligible. However, the interaction of structural factors has different effects on the three indexes. (2) The size of the high temperature zone is the key reason for the formation of NOx. By adjusting the structural parameters, the fuel and oxidizer mixing process is enhanced, local high temperatures are avoided, and thermal NOx emissions are reduced. (3) In several of the cases studied, NO emissions from boilers were below 30 mg/Nm3, and in some cases below 10 mg/Nm3.
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