The Influence Of Structure And Combustion Adjustment Parameters Of Swirling Burners On NO_X Emissions On Lignite-fired Boilers

Nitrogen oxides, referred to as NO_x, is a primary pollution source of coal-firedboilers. NO_xpollutant will cause acid rain and photochemical smog, which seriouslyharms health. According to the latest national standard GB13223-2011, the NO_xemissions limit for coal-fired boilers has been further reduced from the limit of450mg/Nm~3in the standard of2003to100mg/Nm~3, but the NO_xemissions of existingcoal-fired boiler are still far from up to this standards. Hence, NO_xemission reduction isan important task nowadays.In the case of the high cost of the flue gas denitration, furnace denitration is moreeconomical. For the implementation of furnace denitration in existing boilers, variousadjustments can be estimated through numerical simulation, which will provide outlookand is feasible and convenient.In this paper, FLUENT software is used to simulate the combustion of a swirling-combustion lignite-fired opposed-firing boiler in Qinghe Power Plant. It is analysed howto choose the models of turbulence, homogeneous reaction, devolatilization, charheterogeneous reactions and NO_x. Finally, some relatively reasonable setting methods andthe calculated value of NO_xemissions which is close to the measured value are acquiredNext, the furnace and the export zones of a single burner are respectively simulated.As a result, the two keys to reduce NO_xemissions are pointed. It is discussed how NO_xemissions change in different swirling intensity, radial velocity of outer secondary air, thebias, the ratio of outer secondary air, the OFA rate and the number of OFA layers. Theflow field in the export zones of a single burner is also simulated, aimed to analyze thereasons why NO_xemissions change in different conditions.Finally, through the adjustment of these parameters, it is predicted that the NO_xemissions of this boiler will be reduced from418mg/Nm~3to238mg/Nm~3, which isreduced by43%.