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Boiler burners are classified into: a. Diffusion burners, b. Partially premixed (atmospheric) burners, c. Forced draft burners. Among atmospheric burners, there are those that use natural draft and those that use forced air. I. Characteristics of boiler burners (1) High thermal efficiency: It can adapt to pressure fluctuations and adjust the primary air supply automatically (that is, when the gas pressure is high, more primary air is drawn in) ； Low gas pressure results in less primary air being drawn in); combustion is thorough, resulting in high thermal efficiency ； (2) High safety: This burner is equipped with a low flame. When starting the boiler, low heat is applied first; only once the combustion at low heat is stable does the automatic control system open the main gas valve, allowing fuel to enter the boiler for normal combustion and preventing any detonation ； (3) Strong fuel adaptability: This type of burner can be adapted to natural gas, liquefied petroleum gas, city gas, liquefied petroleum gas mixtures, and other types of fuels by simply replacing a few components. II. Analysis of the reasons for burner damage in boilers 1. Excessively high furnace temperature: The temperature at the center of the flame in the furnace is too high, and the high-temperature flue gases in the furnace increase the radiative heat transfer to the burner, resulting in an increase in the temperature of the burner nozzles. This is one of the reasons for burner burnout. 2 Deviation of the furnace flame center: The results of the burner hot-test show that the temperature distribution in the furnace as measured at the four corners, as well as at the burner nozzles, is significantly uneven. A skewed flame center in the furnace can also cause damage to the burner. Based on the measurements of the primary air flow velocity in the air ducts, it is evident that the velocity of the primary air at the nozzles of the burners located in the four corners of the same floor is highly uneven; the primary air velocity at the nozzles on each floor is below the design values. Large wind speed variations at the primary air nozzles in the same layer are one of the reasons for the deviation of the furnace flame center. Large deviations in the primary air velocity, as well as low primary air velocities, can cause damage to the burner nozzles. 3 Reasons related to operation control 3.1 The ignition distance of the coal powder is too short 3.2 A too low primary air velocity can result in a too short ignition distance for the coal powder. During operation, if the total pressure of the primary air controlled is too low, it may result in an excessively short ignition distance, thereby causing the burner nozzles to overheat and deform until they are damaged. 3.3 Too low a secondary air velocity can also result in an excessively short ignition distance, leading to damage to the burner nozzles. 3.4 Impact of coal type changes: As the quality of coal improves and its volatile content increases, the ignition distance of the coal powder at the primary air nozzles becomes shorter. Operators fail to adjust the primary and secondary air in a timely manner to adapt to these changes in coal type. 3.5 The coal powder is too fine. According to the two-month coal quality analysis reports, the combustible basis volatile matter of the coal used in the power plant ranges from 15% to 23%, while the ash content is around 25%. Accordingly, the controlled range for the coal powder fineness R90zj should be 14.5% to 21%; however, the actual value of R90 for the coal powder under operation is around 12%. This results in the ignition distance of the coal powder at the primary air nozzles being too short, leading to overheating and deformation of the burner nozzles, and ultimately to their damage. 3.6 Insufficient cooling of the upper primary air nozzles during low-load operation: During low-load operation, the primary air nozzles that are not in use are almost in a state of dry burning, receiving insufficient cooling; this leads to overheating, deformation, and ultimately damage of the burner. 4. Reasons related to the design of boiler burners 4.1 Material aspects The alloy steel material used for the burners does not meet the requirements for wear resistance and high-temperature tolerance necessary for the proper operation of the boiler. 4.2 In terms of structure, the design of the nozzles in the coal powder concentration and preheating burners is not sufficient; intense heat recirculation at these nozzles leads to excessively high temperatures, causing the nozzles to overheat and become deformed or damaged. III. Countermeasures to Prevent Burnout of Boiler Burners 1. Improving burner design 1.1 Enhancing burner structure and wear resistance For the preheating cylinder of coal dust direct ignition burners, the wall thickness and length of the inner cylinder should be appropriately modified during design; high-quality alloy steel materials should be used to improve wear and heat resistance. For coal powder concentration and preheating burners, the wear resistance of the burner and the high-temperature tolerance of the preheating chamber must be fully considered during design. 1.2 Addition of a perimeter air design to the upper primary air nozzles: Perimeter air can serve the following purpose: during high load conditions, this air is activated; its function is to enhance the intensity of the primary air, prevent the spread of coal powder from eroding the surrounding water-cooled walls, and supply the oxygen required for combustion in a timely manner ； The presence of perimeter wind also weakens the reducing atmosphere near the water wall, preventing high-temperature corrosion of the water wall ； At low load, it can meet the cooling requirements of the upper primary air nozzles when one powder exhaust fan is shut down, thereby preventing damage to the burner. Based on the investigation of boiler burners in power plants in Jiangsu Province, it can be seen that at high loads, the use of peripheral air can effectively control the coal powder ignition distance of the burners. 2 Ensure that the furnace design circle is correct. Take advantage of the downtime to check the installation angle of the burners, to confirm that the furnace design circle is accurate. Conduct uniformity tests for the primary air flow rate in both cold and hot conditions for Furnace No. 2, as well as tests on the baffle characteristics of the secondary air in cold conditions, to ensure that the center of the flame in the furnace does not shift. 3 Strengthen operation control adjustments 3.1 Operators should keep track of any changes in the type of coal fed into the furnace, and based on the coal quality analysis reports, adjust the operation of the coal grinding system accordingly to ensure that the fineness of the coal powder remains within the optimal range. 3.2 Boiler operators should regularly monitor the ignition condition of the coal powder, ensuring that the ignition distance from the outlet of the primary air nozzles is approximately 500–800 mm. Adjust the opening degree of the make-up air valve in a timely manner based on the coal powder concentration and the wall temperature of the preheating burner. 3.3 During both high and low load conditions, operators should adjust the combustion inside the furnace and optimize the ratio of primary air to secondary air to ensure that the flame in the furnace does not deviate. 4 Redo the burner design calculations, taking into account the fact that the current coal type is of better quality than the one specified in the original design. Reperform the burner design calculations. When designing a new burner, it is necessary to consider appropriately reducing the area of the primary air nozzles and increasing the wind speed at these nozzles to 25–28 m/s. After the burner is modified, it is necessary to determine an appropriate installation location for the burner wall temperature thermocouples, so that they can effectively perform monitoring during operation.