Suggestions on low nitrogen burner transformation and operation measures
1、 Research and analysis of fly ash and boiler efficiency.
During the formation of nitrogen oxides, the main factors that affect the formation of nitrogen oxides are: combustion flame temperature, oxygen content concentration in the burner section, time of combustion products in the high temperature area and coal quality. According to these influencing factors, nitrogen oxides can be reduced in the following two ways: first, reduce the combustion flame temperature properly to avoid excessive local temperature; The second is to control the air coefficient in the combustion environment, limit the oxygen content, and ensure the combustion of pulverized coal in the anoxic environment. After transformation, the main combustion zone generally adopts low oxygen combustion with low air coefficient. Only the burnout air at the top can burn, and the pulverized coal will not burn out. The online fly ash collection shows that the fly ash is too large. The increase of boiler fly ash content will lead to incomplete combustion of pulverized coal, thus limiting the combustion efficiency of the boiler. During boiler operation, excessive fly ash particles will also shorten the wear and service life of the heating surface at the rear of the boiler.
2、 Combustion optimization and adjustment after low nitrogen burner transformation.
After the low nitrogen transformation of the burner, the original combustion method must be modified to ensure that the adjusted scheme can meet the safety requirements and meet the relevant ultra-low nitrogen emission standards. Specifically, the emission of NOX should be controlled within the safe concentration index. The following points should be noted:
1. Operation mode of burner. For the transformation of low nitrogen burner, the focus is on how to improve the rated temperature of furnace and the stability of pulverized coal combustion, and try to avoid sudden shutdown or insufficient power of burner.
2. Boiler secondary air distribution mode. The secondary air distribution mode of the boiler shall meet certain basic needs to ensure that the excess air coefficient in the main combustion zone is within a reasonable range; When the burner is shut down, the corresponding damper shall be properly closed, and the opening and closing degree of the damper shall be determined by the corresponding flow curve; During boiler operation, it is necessary to ensure that the air pressure of the bellows is normal and the air pressure is normal.
3. Oxygen content of boiler operation. Control the oxygen content during boiler operation within a reasonable range. The optimal oxygen content during boiler combustion needs to be determined according to the actual combustion test results.
4. Control the accuracy of pulverized coal. If SOFA combustion classification technology is adopted, the accuracy of pulverized coal needs to be adjusted.
3、 Burner transformation and installation.
At the installation stage, the horizontal angle of the burner must be strictly calibrated according to the design requirements. Measure and verify the installation deflection angle of the burner, measure and verify the synchronization of the same angle and swing of the same layer of the burner, and ensure that the nozzle size of the burner, nozzle shaft, and burner circle diameter meet the design requirements.