Factors affecting the effectiveness of low nitrogen combustion transformation
1、 Research and analysis on the influence of superheated and reheated steam temperatures.
After the transformation of the low nitrogen burner, the nozzle of the low nitrogen burner is about 1m lower than before. During the analysis process, based on the bottom burner, the height of the remaining burners moves downwards, causing the flame center to decrease simultaneously, and the heat absorbed by all heating surfaces to decrease, thereby lowering the outlet smoke temperature. The renovated low nitrogen burner has a significant impact on the temperature of the reheated steam. Due to slow coordination of the boiler unit, pressure tracking and adjustment are not coordinated, which can easily lead to excessive adjustment and unstable steam temperature.
In addition, due to the need to pay attention to low oxygen combustion during the primary and secondary air ratio process, the adjustment of steam temperature will be limited to a certain extent, and the entire adjustment time cannot be shortened, and the operating efficiency of the unit cannot be improved. In order to ensure that the outlet temperature is within the standard range, an upper powder manufacturing system can be used in the low load stage, and the height of the nozzle can be appropriately increased. However, this adjustment can allow low nitrogen steam to enter the standard range, which becomes an important issue in the transformation of low nitrogen burners.
During the renovation process, adjustments can be made to the nozzle of the exhaust air. If the nozzle of the exhaust air is adjusted to an upward swinging type, the temperature of the reheated steam will rise. If the nozzle of the exhaust air is adjusted to a downward swinging type, the temperature of the reheated steam will decrease until it is within the standard range. Therefore, Through this principle, appropriate adjustments can be made to the low nitrogen burner during boiler operation.
2、 The blending of coal into the boiler resulted in coking and extinguishing the fire.
Slag and high-temperature corrosion have always been problems for coal-fired boilers in power plants, and their severity can even affect the safe operation of boilers. With the application of low NOX combustion technology, oxygen deficiency in the main combustion zone forms a reducing atmosphere, reduces the ash melting point, and causes slag and high-temperature corrosion; At the same time, staged combustion in the furnace leads to flame extension, difficult coke combustion, and heating of surface slag at the furnace outlet. The melting point temperature of coal ash affects the performance of boiler slag. For boilers that burn low ash melting point coal, most of the low nitrogen burners will experience slagging problems after renovation, which may even affect the safe operation of the boiler.
3、 The boiler was designed to extinguish the fire.
The horizontal cutting angle in the initial stage of boiler burner design can be adjusted. According to some experimental results of the boiler, the A layer of the low nitrogen modified boiler will produce a reverse cutting effect, causing turbulence in the rotating airflow inside the boiler and abnormal changes in wind speed. The stability of the boiler during combustion is not as good as before, resulting in stalling inside the chamber. The burner renovation project is unreasonable, and the design error of the reverse tangent angle of the combustion separator is too large; The renovation design destroyed the original imaginary circle, which is manifested by the larger cutting edge of the secondary air. Due to changes in the horizontal and vertical blunt bodies during the renovation process, the rotational power of the secondary air is insufficient to maintain the stability of domestic flames, and the anti-interference ability is weak, which can easily cause flame jumping and wall sticking.