#Poor quality steam refers to high moisture content, Steam is best when
superheated. From the perspective of Process Design Engineering, we assume
that even saturated steam is dry.
*In reality, steam in most process plant
piping systems is wet. Often steam is wet because of ambient heat loss.
*Dry steam is actually invisible. Steam venting from a line
only looks white because the steam is wet.
*Wet steam is generated
from boilers because of entrainment of BFW into the evolved steam.
*Entrained
boiler feed water contains salts. The TDS of the entrained water is the same as
the boiler blowdown
*Salt content of the blowdown water is 10-20 times >
the salt content of the boiler feedwater. That’s why moisture in steam due to
entrainment is more serious than moisture in steam due to condensation.
Condensed moisture is free of salts.
️*For Steam Turbines Moisture in the
supply steam contains salts. The salts slowly accumulate on the turbine blades
and reduce horsepower output. When these deposits break off, the turbine rotor
is unbalanced. The resulting vibration will cause the shutdown of the turbine.
*️For Steam Superheat Furnace Tubes salts in entrained
moisture from a boiler will deposit inside the superheat coils. Localized
overheating and tube rupture will result.
Comments
Post a Comment