Causes of burning loss of the burner of the hottes

Boiler burner burning causes and Prevention Countermeasures

burner burning causes analysis

1 furnace temperature is high

furnace flame center temperature is high, and the radiation heat transfer of furnace high-temperature flue gas to the burner is enhanced, resulting in the increase of burner nozzle wall temperature. This is one of the reasons for the burning loss of the burner

2 the deviation of the furnace flame center

the hot state test results of the burner show that the furnace temperature measured from the four corners and the temperature distribution of the burner nozzle are obviously uneven. The deviation of the flame center in the furnace will also lead to the burning loss of the burner. From the measurement results of primary air duct wind speed, the primary air velocity at the primary air nozzle of the four corner burner on the same layer is obviously uneven, and the primary air velocity at the nozzle of each layer is lower than the design value. The large deviation of the wind speed at the primary air nozzle on the same floor is one of the reasons for the deviation of the furnace flame center. Large primary wind speed deviation and low primary wind speed will cause damage to the burner nozzle

3 reasons for operation control

3.1 the ignition distance of pulverized coal is too close

3.2 too small primary wind speed will cause the ignition distance of pulverized coal to be too close. During operation, if the total pressure of the primary air controlled is too low, the ignition distance may be too close, resulting in overheating, deformation and damage of the burner nozzle

3.3 too low wind speed of secondary air will also cause too close ignition distance and damage to burner nozzle

3.4 influence of coal type change

after the coal quality gets better and the volatile content increases, the ignition distance of pulverized coal at the primary air nozzle becomes closer and the operator; The test time of air pipeline and air bottle 1 is a lot of 2 hours, and the pressure should not drop significantly. The operator failed to adjust the primary air and secondary air in time to adapt to the change of coal type

3.5 the fineness of pulverized coal is too fine

according to the two month coal quality analysis report, the combustible volatile of the operating coal of the power plant is 15% ～ 23%, and the ash is about 25%, and the corresponding control pulverized coal fineness r90zj should be 14.5% ～ 21%, while the pulverized coal fineness r90 of the operating control is about 12%, causing the ignition distance of pulverized coal at the primary air nozzle to be too close, resulting in overheating, deformation and damage of the burner nozzle

3.6 during low load operation, the cooling of the upper primary air nozzle is not enough

during low load operation, the primary air nozzle that is not put into use is almost in a dry burning state and cannot be cooled enough, resulting in overheating, deformation and damage of the burner

4. There is no more advanced problem between the two. The reason of burner design

4.1 material

the alloy steel material selected for the burner has no side effects and cannot meet the requirements of wear resistance and high temperature resistance of the burner during normal operation of the boiler

4.2 in terms of structure

the structural design of the nozzle of the pulverized coal concentration and preheating burner is not perfect, and strong heat reflux is generated at the nozzle, resulting in excessive nozzle temperature, overheating, deformation and damage of the nozzle

5. Prevention and control measures for burner burning

5.1 improve burner design

5.1.1 improve burner structure and anti-wear performance

for the preheating cylinder of pulverized coal direct ignition burner, the thickness of the cylinder wall and the length of the inner cylinder should be appropriately improved in the design, and high-quality alloy steel materials should be selected to increase the anti-wear and heat resistance. For the pulverized coal concentration and preheating burner, the wear resistance of the burner and the high temperature resistance of the preheating chamber should be fully considered in the design

5.1.2 the design of increasing the peripheral air at the upper primary air nozzle

the peripheral air can play such a role: when the load is high, the peripheral air is on. At this time, the function of the peripheral air is to strengthen the strength of the primary air, prevent the expansion of pulverized coal from scouring the surrounding water-cooled wall, and timely supplement the oxygen required for combustion; The existence of peripheral wind also weakens the reducing atmosphere near the water wall to avoid high-temperature corrosion of the water wall; At low load, it can meet the cooling requirements of the upper primary air nozzle when one pulverized coal exhauster is stopped, so as to prevent the burners from burning out. According to the investigation of boiler burners in power plants in Jiangsu Province, when the load is high, the operation of ambient air can also effectively control the ignition distance of pulverized coal in the burner, and the PWM output frequency is 5MHz

5.2 ensure that the furnace design tangential circle is correct

use the shutdown opportunity to check the installation angle of the burner to ensure that the furnace design tangential circle is correct. Do a good job in the cold and hot homogenization test of the primary air speed of boiler 2 and the cold baffle characteristic test of the secondary air to ensure that the center of the furnace flame is not skewed

5.3 strengthen the operation control adjustment

5.3.1 the operator should timely grasp the changes of the coal type into the boiler, and adjust the operation of the pulverizing system accordingly according to the coal quality analysis report to ensure that the fineness of pulverized coal is in the best range

5.3.2 boiler operators should often observe the ignition of pulverized coal, and control the ignition distance of pulverized coal to be about 500 ~ 800 mm from the outlet of primary air nozzle. Adjust the opening of makeup valve in time according to the wall temperature of pulverized coal concentration and preheating burner

5.3.3 the operating personnel should adjust the combustion in the furnace and the ratio of primary air and secondary air to ensure that the furnace flame does not deflect under high and low load conditions

5.4 re calculate the burner design

for the current coal is better than the original design coal. Re calculate the burner design. When designing a new burner, it should be considered to appropriately reduce the area of the primary air nozzle and increase the primary air nozzle wind speed to 25 ~ 28 m/s. After the transformation of the burner, it is necessary to determine the reasonable installation position of the burner wall temperature thermocouple, so that it can really play a monitoring role in operation. (end)