What is the problem with silica in boiler feed water?
Silica is a problem for high pressure boilers. It exhibits enough volatility that high pressure boilers will have silica carry over to the vapor partition. When the steam pressure is reduced in the low-pressure turbines, the silica will precipitate on the turbine blades as a glassy deposit which reduces turbine efficiency. Both types of silica, reactive and colloidal, can cause this problem. (At the temperatures experienced in high pressure boilers, colloidal silica will decompose to silicate, thus allowing it to evaporize.
