The application of low-nitrogen burners is widespread, and more and more boiler manufacturers have retrofitted their burners with low-nitrogen burners. Riello manufacturers will tell you the advantages and disadvantages of low-nitrogen burners.
1. Advantages of low nitrogen burner:
1. Due to stretching the combustion area, part of the combustion intensity is weakened, and the formation of NOx is suppressed within a certain period of time.
2. Low-load combustion is stable. Because the lower air volume is reduced, the fuel burns very smoothly at low concentration. It can even achieve stable combustion at 40% load.
3. When the load is low, the furnace flame is full. The water wall absorbs heat evenly.
2. Disadvantages:
1. Due to the position of the overfired air, a large amount of supply air does not participate in combustion when it leaves the furnace, and this part of hot air also absorbs a large amount of heat from the air preheater, which will cause the exhaust gas temperature to be too low. Especially at low loads.
2. Due to the weakening of the air intake of the lower furnace, the support ability of the secondary air is weakened, the amount of slag discharge is increased, and the carbon content of the slag discharge is increased, especially when the load is high.
3. Since the air intake in the lower furnace is weakened, the rigidity of the air is weakened, and the combustion area is expanded. When the load is high, coking of the water wall is prone to occur.
4. Due to the lack of oxygen in the lower part of the furnace, a large amount of reducing gas is produced, which reduces the melting point of ash and even causes coking in the cold slag bucket.
5. Due to the stretching of the combustion area, in the period of high load, the overheating of the superheater will be caused, and the amount of desuperheating water will be insufficient. In severe cases, it will even cause coking on the screen.
6. Due to a large amount of reducing gas and the expansion of the combustion area, the middle and lower parts of the water wall are seriously coked, and the phenomena of fire extinguishing, deflagration and damage to the slag removal machine due to decoking have occurred.
7. Because the coking at high load affects the heat absorption of the water wall, the temperature of the lower part of the furnace rises, and the position of the overfire air can only cool the flue gas in the upper part of the furnace, but has no effect on the temperature of the lower furnace, so the lower part of the furnace The generation of NOx increases with coking, and the longer the high load lasts, the smaller the effect of reducing NOx, even exceeding the original NOx amount.
8. The theory of burning volatiles in the lower part of the furnace and burning coke in the upper part of the furnace is different from the theory of "volatile matter precipitation → volatile matter combustion → coke combustion → shell ash peeling off, and volatile matter is continuously precipitated with the peeling of the shell ash" in pulverized coal combustion. match. Therefore, when the load is high, the combustion time of a large amount of pulverized coal is prolonged, and the pulverized coal that is not completely burned is brought into the flue. This increases the carbon content of the fly ash.
The application of low-nitrogen burners is widespread, and more and more boiler manufacturers have retrofitted their burners with low-nitrogen burners. Riello manufacturers will tell you the advantages and disadvantages of low-nitrogen burners.
1. Advantages of low nitrogen burner:
1. Due to stretching the combustion area, part of the combustion intensity is weakened, and the formation of NOx is suppressed within a certain period of time.
2. Low-load combustion is stable. Because the lower air volume is reduced, the fuel burns very smoothly at low concentration. It can even achieve stable combustion at 40% load.
3. When the load is low, the furnace flame is full. The water wall absorbs heat evenly.
2. Disadvantages:
1. Due to the position of the overfired air, a large amount of supply air does not participate in combustion when it leaves the furnace, and this part of hot air also absorbs a large amount of heat from the air preheater, which will cause the exhaust gas temperature to be too low. Especially at low loads.
2. Due to the weakening of the air intake of the lower furnace, the support ability of the secondary air is weakened, the amount of slag discharge is increased, and the carbon content of the slag discharge is increased, especially when the load is high.
3. Since the air intake in the lower furnace is weakened, the rigidity of the air is weakened, and the combustion area is expanded. When the load is high, coking of the water wall is prone to occur.
4. Due to the lack of oxygen in the lower part of the furnace, a large amount of reducing gas is produced, which reduces the melting point of ash and even causes coking in the cold slag bucket.
5. Due to the stretching of the combustion area, in the period of high load, the overheating of the superheater will be caused, and the amount of desuperheating water will be insufficient. In severe cases, it will even cause coking on the screen.
6. Due to a large amount of reducing gas and the expansion of the combustion area, the middle and lower parts of the water wall are seriously coked, and the phenomena of fire extinguishing, deflagration and damage to the slag removal machine due to decoking have occurred.
7. Because the coking at high load affects the heat absorption of the water wall, the temperature of the lower part of the furnace rises, and the position of the overfire air can only cool the flue gas in the upper part of the furnace, but has no effect on the temperature of the lower furnace, so the lower part of the furnace The generation of NOx increases with coking, and the longer the high load lasts, the smaller the effect of reducing NOx, even exceeding the original NOx amount.
8. The theory of burning volatiles in the lower part of the furnace and burning coke in the upper part of the furnace is different from the theory of "volatile matter precipitation → volatile matter combustion → coke combustion → shell ash peeling off, and volatile matter is continuously precipitated with the peeling of the shell ash" in pulverized coal combustion. match. Therefore, when the load is high, the combustion time of a large amount of pulverized coal is prolonged, and the pulverized coal that is not completely burned is brought into the flue. This increases the carbon content of the fly ash.