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Posted by Vern on February 19, 2002 at 07:46:56:
In Reply to: High silica content ! posted by Ramesh R on February 18, 2002 at 19:46:06:
: im having high silica content in my raw water (20 ppm)& in boiler water reading is about 300ppm.Is there any way i can reduce silica content in boiler water to prevent silica scales?what is the permittable amount of silica content in boiler water?
The recommended industry standard for silica in boiler water is 150 to 200 ppm, dependent
upon who you talk to. It has been my experience in boilers operating around 100 psi to 200 psi
steam pressure, silica levels as high as 400 ppm present no problem as long as you maintain
proper alkalinities somewhere between 500 to 1000 ppm. If you wish to lower the level of silica
you presently have, you need to lower your cycles of concentration. To do this you must blowdown
more frequently to remove lots more water. Unless you operate in the higher psi regions, say 600 or
so or higher, I wouldn't worry about it unless visual inspection indicates you are having silica
deposition. To remove silica from raw water use reverse osmosis, or deionization. Hope this helps.