Why do gas-fired boilers emit white smoke during operation?

When the boiler flue gas is saturated wet flue gas, the flue gas contains a large amount of water vapor. At this time, if the flue gas is directly discharged from the chimney and enters the low-temperature ambient air, and the saturated humidity of the ambient air is relatively low, the water vapor in the flue gas will condense to form wet plumes, which is often called "white smoke".

The water in the flue gas of the boiler is produced during the combustion of the hydrogen element of hydrocarbon, which is discharged into the atmosphere and condensed to cause white smoke. Removing white smoke in the boiler is to change the flue gas temperature or humidity to avoid the condensation of supersaturated water vapor caused by the decrease of flue gas temperature in the process of mixing flue gas with ambient air, thus reducing the water carried by flue gas, further reducing pollutant emissions and eliminating visual white smoke.

There are mainly the following three methods for the removing white smoke during operation:

1. Direct heating of flue gas

The relative moisture content of the wet flue gas decreases, and the wet flue gas will not become saturated in the process of changing from state point B to ambient air state point F, and will not form wet plume;

2. Cooling and reheating

The absolute moisture content of wet smoke can be reduced and the relative moisture content of wet smoke can be reduced, and the wet smoke plume will not be formed in the process of changing into ambient air state point F;

3. Direct cooling of flue gas

Direct flue gas cooling will change the state point of wet flue gas from A to E, and the wet flue gas will not become saturated and will not form wet plume in the process of changing from E to F of ambient air.

The flue gas of coal-fired boilers is mostly wet desulfurized before being discharged. When the temperature drops to a certain temperature, the flue gas at this time is usually saturated wet flue gas, which contains a large amount of water vapor, which contains more soluble salts, SO3, gel dust, fine dust, etc. (all of which are the main components of smog).

In view of the phenomenon of white smoke feedback from ZOZEN users, ZOZEN Boiler will analyze the specific reasons according to the actual operation of gas-fired boilers, and give reasonable suggestions for eliminating white smoke from gas-fired boilers. Please consult online customer service for details.