Low nitrogen combustion transformation and operation optimization adjustment of boilers in thermal p - self recycling burner

Low nitrogen combustion transformation and operation optimization adjustment of boilers in thermal power plants
The emissions of nitrogen oxides (NOx) during low nitrogen combustion pose a threat to the ecological environment and human health. By adopting specialized methods to carry out low nitrogen combustion transformation and optimize operation of boilers, NOx emissions can be effectively controlled, production efficiency can be improved, and environmental and ecological problems can be reduced. This article provides a brief analysis of the current status of low nitrogen combustion technology, and proposes a renovation plan and optimized operation process for low nitrogen burners.
China attaches great importance to the emission of atmospheric pollutants from thermal power plants and has introduced various laws, regulations, and prevention policies. In addition to considering economic benefits, thermal power plants also take into account environmental issues during their development process, considering how to reduce the emissions of atmospheric pollutants and proposing effective implementation methods. In fact, the renovation of power plant boilers can effectively control NOx emissions, reduce environmental and air pollution, and achieve environmental benefits and goals.
1、 Current status of low nitrogen combustion technology.
Reducing NOx emissions can effectively control air pollution. In terms of production technology, low nitrogen combustion technology is mainly used, with flue gas denitrification as an auxiliary. Among these factors, the mechanism of nitrogen generation is related to low nitrogen combustion technology, with the main constituent elements being low oxygen combustion and flue gas recirculation. Vertical arrangement of burners promotes the formation of three plates in the oxidation-reduction, main reduction, and burnout zones. This process can also place the burners in appropriate positions according to different boiler conditions, facilitating low-temperature and low oxygen combustion of organic dyes and air distribution in the boiler, and achieving zoning and classification, effectively controlling NOx emissions to achieve good clean combustion effects.
2、 Low nitrogen burner renovation plan.
1. Select the burner.
According to actual needs, develop a scientific plan for the transformation of low nitrogen burners, as a reference, and optimize them. Horizontal and vertical thick thin burners are widely used in China. The former main function is to separate the coal powder in the horizontal direction, separating its concentration and dilution. It is widely used in desulfurization work in the furnace. In desulfurization work in the furnace, the jet is inclined towards the center position of the furnace, and has a strong effect of direct suction and wind bag coal. The vertical concentration and dilution burner has the same principle, but the usage process is exactly the opposite. It is mainly responsible for the vertical separation of coal powder, and the implementation effect is very good. The selection of burner type should not be blind. In addition to isolating the thick and thin coal powder in the furnace, it is also necessary to comprehensively grasp the separation ratio, various parameters, etc., and it is strictly prohibited to have low nitrogen residue in the furnace.
2. Renovation of the main burner.
The transformation of the main burner not only requires determining the standard height of the main burner, but also scientifically fixing the air ducts and positions of the four air boxes, replacing all nozzles, elbows, etc., to ensure that all components can meet the standards. The last layer exists in the form of an axially inserted plasma burner, which can also convert the remaining primary air burner into a thick and thin burner, with upper concentration and lower dilution or lower concentration and upper dilution. In this context, the use of high heat-resistant steel plates is effective. The secondary air nozzles in the middle of the four layers remain closed, while replacing the remaining secondary air nozzles. The layout of the wall attached air nozzles should also be considered to ensure that the surface layer of the water-cooled wall has sufficient oxygen to avoid excessive furnace temperature caused by insufficient oxygen, resulting in excessive furnace temperature, slagging, and corrosion. In addition, the remaining secondary air nozzles need to be changed to change the direction of the jet, with a focus on controlling the angle of the primary air and other secondary air nozzles, so that the oxygen deficient fuel in the early stage and the oxygen supplied in the later stage can be fully mixed.
3. Scientifically design OFA nozzles and secondary air.
Although the boiler combustion system is relatively complex, the structure of the OFA nozzle is relatively simple and widely favored in the industry. In practical application, it is necessary to apply the OFA nozzle again on the basis of the original system, leverage its advantages, take into account the anti tangential effect, effectively control the airflow inside the furnace, and make the temperature of the furnace outlet normal. Assuming that the original OFA nozzle size, wind speed setting, air volume, and other indicators cannot meet the requirements of low nitrogen combustion technology transformation, the heat-resistant version can be directly sealed or subjected to secondary transformation. The upper end of the burner is equipped with a large proportion of secondary air, which is conducive to air classification in the furnace, reduces nitrogen oxides, and enables the boiler to achieve full combustion. When designing secondary air, it is also necessary to consider indicators such as the location and area of the burnout zone.
3、 Optimization operation plan for nitrogen combustion.
1. Optimize and adjust the boundary wind of primary and secondary air.
The variation of air flow rate has a certain impact on the concentration of nitrogen oxides. If the air flow rate is too high, the furnace oxygen content and the concentration of nitrogen oxides will be lower. Based on the adjustment of the operating status of each power source and the comparison of air distribution methods such as forward and reverse tower, it can be seen that the air distribution operation of reverse tower produces less nitrogen oxides and has no impact on the atmosphere. Starting from the equivalent indicators of nitrogen oxides and boiler combustion efficiency, the opening of secondary air in each layer should not exceed 70%, and the opening of secondary air in the upper layer and the opening of each layer should be between 35% and 15% -20%, respectively.
2. Adjust the swing angle of the burner and exhaust air.
It is very important to study the generation of nitrogen oxides during low nitrogen combustion and adjust the swing angle and exhaust air of the burner. Adjusting the angle of the combustion air swing to tilt the furnace upwards can not only avoid the deviation of the furnace temperature on both sides, but also achieve a better swing angle and shorten the operating time. Optimization and adjustment of the burnout air, while stabilizing the total composition of the boiler, increases the area of the burnout air baffle according to specific operating conditions, effectively controlling the emission of nitrogen oxide and fly ash parameters.
3. Adjust the oxygen content in the furnace.
In fact, scientifically adjusting the furnace oxygen content can also optimize the operation process of low nitrogen combustion. Control the oxygen content of the furnace gas to avoid excessive production of nitrogen oxides. Under lower oxygen content conditions, the furnace will produce a small amount of nitrogen oxides. The experimental results indicate that if the oxygen content in the furnace is too low, it will increase the combustible content of fly ash. Therefore, the oxygen content in the furnace should be scientifically controlled between 2.5% and 3.5%. While effectively controlling nitrogen oxide emissions from thermal power plants, boiler combustion efficiency should also be considered.
4. Conclusion
The low nitrogen combustion transformation project of thermal power plant boilers has high technical content, high technical standards, high professional requirements, and complex implementation process. It can significantly improve the combustion efficiency of boilers, effectively control the emission of nitrogen oxides, and improve the daily work and service quality of thermal power plants. With the improvement of environmental awareness, relevant practitioners need to protect the quality of the ecological environment, upgrade and transform the low nitrogen combustion of boilers according to external conditions, make them meet the requirements of process production and social development, improve equipment performance, and achieve production and environmental benefits.