The combustion condition of the low nitrogen burner is not only affected by the air distribution condition, but also related to the load of the burner.
In order to ensure the correct flame center position and avoid flame deflection, the load of each burner put into operation should be distributed as evenly and symmetrically as possible, that is, the air volume and powder feeding volume of each burner should be adjusted to be consistent. But in practice, the powder feeding amount of each nozzle cannot be exactly the same. In addition, due to differences in structure, installation, manufacture and arrangement, the characteristics of each burner cannot be exactly the same. Burners that are suitable for high loads may not be suitable for low loads; the adaptability of each burner to coal types and the influence on steam temperature, flame distribution, slagging, etc. are also different.
In terms of the operation mode of coal mills, A, B, C, and D mills are the main coal mills, and E and F coal mills are generally used as backup mills, and some power plants will use A mill as a backup mill when designing. When it is necessary to start the spare coal mill for loading, it should be determined according to the overall operation of the boiler. Starting the upper-layer pulverizing system can increase the main and reheat steam temperature, but the exhaust gas temperature will increase accordingly, and the heat loss of the mechanical incomplete combustion will increase; starting the A-layer pulverizing system, the combustion stability is good, and the exhaust gas temperature and mechanical incomplete combustion will increase. The heat loss of complete combustion is reduced, the heat absorption of the water wall is strengthened, and the temperature of the main and reheated steam of the boiler is reduced. The phenomenon of high steam pressure and low steam temperature during high-load operation can be solved by blowing soot in the flue, switching the operation of the upper pulverizing system, adjusting the speed of each coal feeder and the opening of the auxiliary wind baffle.
When the load is high, due to the high heat load of the furnace, the ignition and combustion are relatively stable. The main problems are high steam temperature and easy slagging. Therefore, care should be taken to keep the steam temperature stable during high-load operation, and at the same time try to avoid slagging. When the boiler is running at low load, the heat load of the furnace is low and it is easy to extinguish the fire. Therefore, we should first pay attention to maintaining the stability of combustion and the influence on steam temperature, and then consider economic indicators. In order to prevent fire extinguishing, the negative pressure value of the furnace can be appropriately reduced, the auxiliary wind baffle between the operating burners should be closed, the fuel volume and air volume should be adjusted to be uniform, and excessive fluctuations in wind speed should be avoided, and the monitoring of poorly burning nozzles should be strengthened . If necessary, an oil gun can be used to support the combustion and stabilize the flame.
When the boiler is running at low load, as long as the stability of the ignition and combustion process can be maintained, the number of coal mills should be reduced and the concentration of pulverized coal should be kept as high as possible. Of course, in order to increase the concentration of pulverized coal, the corresponding mill air volume and total boiler air volume should be reduced to ensure that the combustion at this time still works under a good air-to-powder ratio. This is not only conducive to mutual ignition between flames, but also easy to adjust and adapt to load changes; moreover, this operation is also better for air powder mixing and flame fullness, which can make combustion more stable and complete.
The swing-type direct current burner arranged at four corners is quite effective in adjusting the position of the combustion center and changing the combustion perfection of the steam temperature and pulverized coal, so attention should be paid to making full use of the adjustable inclination angle of this burner. Generally, under the condition of ensuring normal steam temperature, increase the downtilt angle as much as possible to obtain higher combustion economy, but care should be taken to avoid slagging of the cold ash hopper due to excessive temperature, and attention should also be paid to the adjustment of the burner inclination angle. The four corners are not linked, destroying the combustion dynamic field in the furnace. The speed can be faster when the inclination angle of the burner is adjusted at high load, and the speed should be slowed down as much as possible at low load.
In addition to the situation of forced shutdown, sometimes when the boiler is running at low load, in order to maintain the rationality of the primary and secondary air speeds of the burner, it is necessary to stop using a layer of burners. Under normal circumstances, which layer of burners should be stopped? , should be considered comprehensively. Under the load permitting conditions, the burners in A, B, C, and D layers should be kept running as much as possible, and from the perspective of operation, economy and safety should be considered.
In the process of switching on and off the burner or changing the load of the burner, attention should be paid to the coordination of its air volume and coal volume. When the coal mill is out of service due to maintenance failure, due to the possible interlayer operation, the operation mode must be reasonably arranged. The impact on high load is small. At low load, attention should be paid to stable combustion. burn.
The combustion condition of the low nitrogen burner is not only affected by the air distribution condition, but also related to the load of the burner.
In order to ensure the correct flame center position and avoid flame deflection, the load of each burner put into operation should be distributed as evenly and symmetrically as possible, that is, the air volume and powder feeding volume of each burner should be adjusted to be consistent. But in practice, the powder feeding amount of each nozzle cannot be exactly the same. In addition, due to differences in structure, installation, manufacture and arrangement, the characteristics of each burner cannot be exactly the same. Burners that are suitable for high loads may not be suitable for low loads; the adaptability of each burner to coal types and the influence on steam temperature, flame distribution, slagging, etc. are also different.
In terms of the operation mode of coal mills, A, B, C, and D mills are the main coal mills, and E and F coal mills are generally used as backup mills, and some power plants will use A mill as a backup mill when designing. When it is necessary to start the spare coal mill for loading, it should be determined according to the overall operation of the boiler. Starting the upper-layer pulverizing system can increase the main and reheat steam temperature, but the exhaust gas temperature will increase accordingly, and the heat loss of the mechanical incomplete combustion will increase; starting the A-layer pulverizing system, the combustion stability is good, and the exhaust gas temperature and mechanical incomplete combustion will increase. The heat loss of complete combustion is reduced, the heat absorption of the water wall is strengthened, and the temperature of the main and reheated steam of the boiler is reduced. The phenomenon of high steam pressure and low steam temperature during high-load operation can be solved by blowing soot in the flue, switching the operation of the upper pulverizing system, adjusting the speed of each coal feeder and the opening of the auxiliary wind baffle.
When the load is high, due to the high heat load of the furnace, the ignition and combustion are relatively stable. The main problems are high steam temperature and easy slagging. Therefore, care should be taken to keep the steam temperature stable during high-load operation, and at the same time try to avoid slagging. When the boiler is running at low load, the heat load of the furnace is low and it is easy to extinguish the fire. Therefore, we should first pay attention to maintaining the stability of combustion and the influence on steam temperature, and then consider economic indicators. In order to prevent fire extinguishing, the negative pressure value of the furnace can be appropriately reduced, the auxiliary wind baffle between the operating burners should be closed, the fuel volume and air volume should be adjusted to be uniform, and excessive fluctuations in wind speed should be avoided, and the monitoring of poorly burning nozzles should be strengthened . If necessary, an oil gun can be used to support the combustion and stabilize the flame.
When the boiler is running at low load, as long as the stability of the ignition and combustion process can be maintained, the number of coal mills should be reduced and the concentration of pulverized coal should be kept as high as possible. Of course, in order to increase the concentration of pulverized coal, the corresponding mill air volume and total boiler air volume should be reduced to ensure that the combustion at this time still works under a good air-to-powder ratio. This is not only conducive to mutual ignition between flames, but also easy to adjust and adapt to load changes; moreover, this operation is also better for air powder mixing and flame fullness, which can make combustion more stable and complete.
The swing-type direct current burner arranged at four corners is quite effective in adjusting the position of the combustion center and changing the combustion perfection of the steam temperature and pulverized coal, so attention should be paid to making full use of the adjustable inclination angle of this burner. Generally, under the condition of ensuring normal steam temperature, increase the downtilt angle as much as possible to obtain higher combustion economy, but care should be taken to avoid slagging of the cold ash hopper due to excessive temperature, and attention should also be paid to the adjustment of the burner inclination angle. The four corners are not linked, destroying the combustion dynamic field in the furnace. The speed can be faster when the inclination angle of the burner is adjusted at high load, and the speed should be slowed down as much as possible at low load.
In addition to the situation of forced shutdown, sometimes when the boiler is running at low load, in order to maintain the rationality of the primary and secondary air speeds of the burner, it is necessary to stop using a layer of burners. Under normal circumstances, which layer of burners should be stopped? , should be considered comprehensively. Under the load permitting conditions, the burners in A, B, C, and D layers should be kept running as much as possible, and from the perspective of operation, economy and safety should be considered.
In the process of switching on and off the burner or changing the load of the burner, attention should be paid to the coordination of its air volume and coal volume. When the coal mill is out of service due to maintenance failure, due to the possible interlayer operation, the operation mode must be reasonably arranged. The impact on high load is small. At low load, attention should be paid to stable combustion. burn.