The Advantages and Disadvantages of Low NOx Burners
The Advantages and Disadvantages of Low NOx Burners
Advantages of low NOx burners
Due to the stretching of the combustion zone, some of the combustion intensity is weakened, and the components of NOx are inhibited for a certain period of time. Low load stable combustion. Due to the reduction of air volume below, fuel combustion in low concentration is also very stable. It can even achieve stable combustion at 40% load. When the load is low, the flame in the furnace is full. The heat is uniformly absorbed by the water-cooled wall.
Disadvantages of low NOx burners
Due to the position of the air for complete combustion, many air currents leave the furnace without participating in combustion, and this part of the hot air also absorbs a large amount of heat from the air preheater, which will cause the phenomenon of low exhaust gas temperature. Especially at low load. Due to the weakening of the air inlet below the furnace, the support of the secondary air below may be weakened, and the amount of slag and the carbon content of the slag will increase, especially at high loads. Because it weakens the air inlet below the furnace, the rigidity of the air decreases, and the combustion area expands. When the load is high, the water-cooled wall is only carbonized. Due to the low oxygen combustion in the bottom of the furnace, a large amount of reducing gas is produced, reducing the ash melting point, and even forming a cold slag hopper with carbon deposition. Due to the extension of the combustion zone, overheating and insufficient water cooling of the superheater will occur during high load. In serious cases, even a sieve bed carbonization phenomenon can occur. Due to the expansion of many recuperative gases and the combustion zone, serious carbon deposition occurs in the lower middle of the water-cooled wall. There will be phenomena such as extinguishing, violent combustion, and damage to the slag-conveying machine due to carbon removal. High-load carbonization affects the heat absorption of the water-cooled wall, causing the temperature at the bottom of the furnace to increase. Due to its position, the overfire air can only cool the upper flue gas, which has no effect on the temperature at the bottom of the furnace. Therefore, the increase in NOx at the bottom of the furnace increases carbonization. The longer the duration of high load, the smaller the reduction effect of NOx, and even exceed the original NOx level. The combustion of the evaporative part in the furnace bottom and the theoretical “evaporative part” → evaporation combustion → carbon combustion → In the case of ash shedding, the theoretical “continuous separation of ash from the situation” does not match. Therefore, when the load is high, the burning time of a large amount of coal powder is prolonged, and unburned coal powder enters the flue gas. Adding fly ash carbon content is formed.