Foaming is the formation of thick layer of steam bubbles on the top of the water surface inside the boiler due to:
> Increased level of dissolved solids
> High impurities
> Increase in water level
> High dosage of chemicals
How to Prevent Foaming
To prevent foaming, surface or scum blow down should done frequently to expel any floating impurities for the boiler and no lube oil should be allowed to enter the boiler.
Priming
Priming is the condition in which large amount of water are carried along with the steam into the steam line because of,
> Excessive foaming
> Improper amount of steam space
> By a sudden rush of steam (Eg: Sudden opening of steam stop valve)
Action In Case Of Priming & Foaming
> Scum Blow Down
> Reduce boiler feed rate
> Check Chemicals are excess
> If the situation is bad shut down boiler do the servising