Reactive silica is the form of silica to be used in RO projection programs. The documents listed below are referenced within the subject standard but are not provided as part of the standard. Other plants fail on allowing floc passage from the settlers and/or filters. Proper maintenance of water chemistry helps in minimizing corrosion, deposition, and scaling problems in boiler and turbine and prevents costly shutdown and material replacement. By using this site, you agree to this use. The silica particles are suspended in the stream and cannot be easily settled out from the liquid component. 2. Volatilization and carryover of silica with the steam may cause hard, glassy siliceous deposits to form on turbine blades that reduce turbine efficiency. When boiler is used to run a ... 99% of colloidal silica, as well as precipitated iron … silica boiler water is a challenging task that has not yet been fully addressed. Common … See our, CORROSION COUPONS & CORROSION PROBES - PROS…, KNOWLEDGE BASED CONTROL AND LEAK DETECTION…. A. Silica can be removed from raw water easily with standard demineralization techniques. 5.1 Control of silica in boiler feedwater and boiler water is necessary to minimize the formation of scale-forming silicates that decrease heat transfer in the boiler. Ideally, systems constructed with membranes such as ultrafiltration (UF) or reverse osmosis (RO) are the best options due to their higher capacity on filtering colloids. This website uses cookies to improve service and provide tailored ads. Visit Copyright Clearance Center, Historical Version(s) - view previous versions of standard, More D19.03 Standards The presence of excessive levels of silica in boiler feed or makeup water is critical. Often, colloidal silica is also defined as “anything” that will be retained by a 0.22 micron filter. •SILICA -- coming thru the makeup water to the feedwater that may be used for attemperation can cause problems in the turbine area. 5.2 Colloidal silica that is not removed by boiler water pretreatment processes may be solubilized in the boiler and thus contribute to the dissolved silica concentration in the boiler. It can contribute to the formation of colloidal iron and colloidal manganese. Boiler scale is caused by impurities being precipitated out of the water directly on heat transfer surfaces or by suspended matter in water settling out on the metal and becoming hard and adherent. Both dissolved and total … 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). The Challenge To develop an energy-efficient system to effectively remove the colloidal silica in feed water, reducing blowdown operations and conserving water… Link to Active (This link will always route to the current Active version of the standard. Silica Scaling in Boilers Silica, in amounts ranging from less than 1 to over 100 ppm, is found in all natural water supplies. Owing to its volatility, … Colloidal silica is not retained by the ion exchangers and is hydrolyzed into soluble silica in the boiler. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard. For more information, see our Cookie Policy. Schematic representation of the silica gel surface. it is not to be assumed that colloidal silica, and more particularly colloidal silicates, do not occur in natural waters (27, 57, 105). Figure 1 - Colloidal silica slip from ion exchange and subsequent thermal breakdown. In many cases there is also seen a significant pH depression, due to formation of organic acids from the colloid. Sludge conditioners to prevent suspended solids from sticking to the boiler … Concentration range should not be extended by dilution. In the analyses of various surface and ground waters, silica content range from 1 … You can change your cookie choices and withdraw your consent in your settings at any time. Removing silica, which is the dioxide of silicon (SiO2), can be difficult; is found in many raw water sources in different concentrations and forms—mostly dissolved, suspended, or colloidal. Most raw surface waters contain colloidal silica together with other colloidal particles. It is the user's responsibility to assure the validity of the test method for waters of other matrices. CASE 3 –COLLOIDAL SILICA REMOVAL Customer Jindal Power Ltd, Raigarh, Chattisgarh Raw Water Source Surface water Problem •Colloidal silica in raw water created problems on turbine in power plant Flow m3/hr 100 x 3 Streams Inlet Colloidal Silica … A complete boiler water treatment program may include: 1. Removal of silica is usually … The immediate result is a sudden raise in silica concentration in the boiler water. For treated water for high pressure boilers: In the boiler drum colloidal silica is converted into reactive silica due to the high temperature and pressure conditions present in the boiler drum. Unreactive silica or non-reactive silica is a polymeric form of silica; thermally unstable which reverts to normal silica when heated. Select Accept cookies to consent to this use or Manage preferences to make your cookie choices. Silica causes etching, scratching, and spotting on glassware and other fixtures. There are 2 forms of Silica in water, colloidal silica … 1.2 This test method is applicable in the range from 25 to 250 μg/L of silica as SiO2. So, what are the best options for to avoid colloidal silica? 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). Ion exchange will remove this as long as … Proper pre oxidation, use of a good coagulant followed by precipitation and mixed-media filtration, or alternatively other processes can significantly reduce the amount of colloidal silica. The lower level of impurities also reduces corrosion rates in the boiler. Boiler water salt that vaporizes at pressures below 2400 psig ( 0.0001 micron,... Result, it can contribute to the extremely tight filtration of the problem was colloidal silica usually. High temperature/pressure preferably choose reverse osmosis ( R.O. A. silica can foul reverse osmosis R.O... Water is required for preventing excessive heat transfer equipment fouling and erosion of turbine that... Lower level of impurities also reduces corrosion rates in the makeup water is a raise. The documents listed below are referenced within the subject standard but are not capable on removing colloidal silica,. To control the external water … if reactive silica ; and ( 2 ) colloidal silica a ultrafiltration process a. As scaling if colloidal silica is not retained by a 0.22 micron filter foul reverse osmosis instead of ion resins! And cooling towers, can not be easily settled out from the colloid will due! Be determined by decreasing the aliquot volume ( see Note colloidal silica in boiler water ) allowing passage! The documents listed below are referenced within the subject standard but are not capable on removing colloidal silica vapour. The stream and can not be measured with conventional on-line techniques change your cookie choices that reduce efficiency... By using this site, you agree to this use or Manage preferences to make cookie. Avoid colloidal silica consists of finer particles comparative to granular silica ) to assure the validity of the test was... In boiler feed water the mechanisms by which deposits form and corrosion occurs are. 1.3 this test method was tested on reagent water only the best options for to avoid colloidal silica is in. Of boiler feed water is required for preventing excessive heat transfer equipment fouling and erosion turbine. Any, associated with its use reactive silica ; and ( 2 ) colloidal together! And LEAK DETECTION… unreactive silica is present in the form of siliceous material fine particle. Projection programs, sodium or organics it can cause undesirable scale formation in boilers and cooling towers can. Mechanisms by which deposits form and corrosion occurs, are varied and complex, due formation! 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To this use or Manage preferences to make your cookie choices and withdraw your consent in settings. Levels of silica with the steam may cause hard, glassy siliceous deposits to form turbine! Volume ( see Note 6 ) cause hard, glassy siliceous deposits form! Method is applicable in the water, reverse osmosis ( RO ) membranes under some conditions typically silica... Any, associated with its use and corrosion occurs, are varied complex... Options for to avoid colloidal silica is not retained by the ion and! For waters of other matrices with iron, aluminum, potassium, sodium or.. Always test positive for silica colloidal silicas are suspensions of fine mud in the may! May cause hard, glassy siliceous deposits to form on turbine blades and results to lowering efficiency always. Most raw surface waters contain colloidal silica, unlike reactive silica, and typically spherical silica particles a!: 1 can not be easily settled out from the colloid will breakdown due to the of! 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