Why do we test for silica in boiler water?
Boiler water will always test positive for silica because of the small reactive SiO2 leakage by the demin plant. A colloidal silica slip will significantly increase the SiO2 levels in the boiler water, well above typical values of 2-20 ppm (for pressures > 900 psig).
What is silica in boiler water?
Silica is the only boiler water salt which vaporizes at pressures below 2400 psig. It can vaporize at pressures as low as 400 psig. This has caused deposition problems in numerous turbines. The solubility of silica in steam increases with increased temperature: silica becomes more soluble as steam is superheated.
How do I control silica in my boiler water?
After silica enters the boiler water, the usual corrective action is to increase boiler blowdown (to decrease the boiler water silica to acceptable levels) and then to correct the condition that caused the silica contamination.
What causes high silica in water?
Water passing through or over the earth dissolves silica from sands, rocks and minerals as one of the impurities it collects. The silica content in natural waters is commonly in the 5 to 25 mg/L range, although concentrations over 100mg/L occur in some areas.
Why does silica increase in boiler drum?
Due to silica content in the feed water goes to steam drum where separation of wet steam and water takes place and in this way silica content increased in Boiler drum.
How do you treat silica in water?
If reactive silica is present in the water, reverse osmosis (R.O.) is the most appropriate treatment approach in a residential environment. Due to the extremely tight filtration of the R.O. membrane (0.0001 micron), the membrane separates the silica from the water. R.O. will reduce both reactive and colloidal silica.
Is silica safe in water?
Fortunately, like hard water, silica does not pose a danger to health. Silica is not considered harmful if ingested in small quantities in drinking water. In fact, many foods such as onions, wheat, oats, root vegetables, and strawberries contain silica.
What causes foaming in boiler?
Bubbles or froth actually build up on the surface of the boiler water and pass out with the steam. This is called foaming and it is caused by high concentration of any solids in the boiler water.
What is silica testing?
The silica physical exam requires that a PLHCP reviews the employee’s complete medical and job history. Employees will be asked about exposure to silica and other chemicals, breathing problems, tuberculosis, tobacco use, and any heart conditions.
How does silica increase in boiler drum?
Silica build-up is monitored inside the boiler drum. The silica concentration is distributed between the water and vapour phases in a boiler. As the temperature and pressure are increased, more silica becomes present in the steam.
How do I remove silica from my water supply?
Silica can be removed by reverse osmosis or by strong base anion resin.