(1) Insufficient air volume, improper air distribution, low furnace temperature: boiler usually equipped with air preheater, but when the air preheater has leakage, hot air flow doesn’t satisfy the need of burning, smoke will happen.

(2) In the case of stalling situation in full automatic oil-fired boiler: significant increase of furnace negative pressure, no flame can be seen from the inspection hole, steam pressure and steam temperature drop, the steam flow decreases sharply. The water level drops suddenly and then rises sharply.

(3) Incomplete fuel burning: this is the main cause of boiler smoke, in the operation, some combustible gases such as carbon monoxide, hydrogen, methane will be generated in addition to carbon dioxide, sulphur dioxide, water vapor and oxygen, nitrogen, etc. during incomplete combustion. They burn and generate black smoke. Incomplete combustion of fuel will not only lead to black smoke, but also increase the use of fuel, increasing the operating cost of enterprises.

(4) Bad atomization effect of fuel oil and secondary combustion of gas duct: especially when high viscosity residue is burned, black smoke will come out of the boiler due to bad atomization effect.

Troubleshooting:

(1) Timely and appropriately feed into the root air inlet, adjust the primary and secondary air, mix oil mist and air correctly, and prevent hypoxia.

(2) Avoid excessive discharge, leading to insufficient oxygen intake and insufficient combustion.

(3) Ensure that oil supply, oil return pressure and fuel viscosity index are correct in boiler operation.

(4) Try to raise the temperature of air and furnace.