Title of Invention	"A NOVEL METHODOLOGY/PROCESS TO DETERMINE COLLOIDAL SILICA IN RAW & DM WATER."
Abstract	This invention relates to a novel clean process to determine colloidal silica in raw and DM water using microwave power (800 watt) at 200-260°C, 60 Bar pressure wherein colloidal silica gets converted into reactive silica in closed system.

Full Text

"A novel methodology/process to determine colloidal silica in raw & DM water." Field of Invention This invention relates to a methodology to determine colloidal silica in raw & DM water. Background of Invention Silica is generally found in water supplies in three different forms; reactive, colloidal and suspended particles (e.g., sand). The reactive silica can easily be determined and removed, whereas colloidal silica creates problems for water treatment due to its stability as an un-ionized compound, making it difficult to remove using ion-exchange resins 8B conventional filtration methods. Colloidal silica estimation methods are time consuming (lengthy analytical methods) and are not standardized. Moreover, standard colloidal silica solutions are not available. As such there is a need to optimize the methodology for the determination of colloidal silica. Most of the process industries are facing the problems of colloidal silica. This leads to increased alum dosing and higher blow down. The problem becomes acute during rainy season when colloidal silica levels in raw water go very high. The colloidal silica is observed in the range of 2-20 ppm in raw waters, and 0-0.5 ppm in DM waters used for boiler feed water. In absence of a suitable analytical method for colloidal silica & due to its non reacting nature (particle size 10-100 nm), it is difficult to control in the pre-treatment and DM stage and this enters in the feed water & eventually into boiler/steam cycle. It can cause resin fouling and turbine deposit. Often operating steam pressures have to be reduced in order to avoid silica carryover and deposition on the turbine blades. These deposits are hard to remove, cause vibrations in turbine and reduce operating efficiency. In view of the impact of colloidal silica on power plant components it was felt that a detailed analysis/investigation of colloidal silica in water system including Raw water 8B DM water, is necessary to improve power plant performance. Colloidal silica is considered as most detrimental contaminant in process water mainly due to its properties like its polymeric nature and non responsive nature for colorimetric analysis. Not many reports are available on testing of colloidal silica in raw and DM water. As such there is a need to optimize the methodology for the determination of colloidal silica and to assess the efficacy of different control technique for colloidal silica removal. Colloidal silica is known to get convert into reactive silica at high temperature and pressure condition. Therefore, it gets carried over with steam and deposited in later stages of turbine blades at lower temperature, pressure conditions. Silica in water has two parts colloidal ( polymeric silica) and reactive silica. Only reactive silica can be checked/controlled using different pretreatment methods but colloidal silica escaped undetected ( due to its non reactive nature). In all the known methods the colloidal silica is converted into reactive silica. After conversion there is increase in silica content in sample. Colloidal silica is determined by difference between silica before and after treatment. Different analytical methods which are in practice have one problem or other as revealed by following data i.e. results are not consistent, conversion to reactive silica not complete, solution gets turbid or hazardous chemicals are used. The method being filed is clean method without using hazardous chemical, gives consistent results and also offers a altogether a new concept i.e. other than chemical method for conversion of colloidal into reactive silica. The process under claim is novel/unique and based on the principle of conversion to colloidal to reactive silica using microwave power under given conditions. Method-1: HF Boric acid: DM water sample treated with HF + ZrOC12, followed by heating 8B addition of boric acid (Table Removed) Limitation: Inconsistent results, Conversion not complete, solution get turbid Method 2: Alkali molybdate method; Samples were treated with 0.1M KOH and heated at high temperature (225°C) in Teflon beaker (Table Removed) Limitations: Though there was some conversion but heating in open conditions causes loss of sample by evaporation, so results were erratic. Method 3: Bomb digestion method followed by AAS/ spectrophotometric analysis for colloidal silica estimation. (Table Removed) Samples were heated in a digester bomb to develop the pressure inside. There was no improvement in the silica concentration before and after the treatment. No conversion takes place. Objects of Invention The main object of this invention is to develop a process to determine colloidal silica in raw & DM water. Other object is to check the ingress of silica into the steam leading to glassy deposits on turbine blade which causes imbalance and loss of generation through precise measurement of silica. Another object is to develop a process wherein reaction of colloidal silica with other boiler water contaminants which causes boiler tube deposits can be minimized. Yet another object is to check the fouling of the resin in ion exchanger beds. Further object is to avoid hazardous chemical for the determination of colloidal silica unlike other process. Other object is to develop a process wherein the complete conversion of colloidal into reactive silica is assured. Another object is also to analyze colloidal silica quantitatively using a clean method. Statement of Invention This invention relates to a novel clean process to determine colloidal silica in raw and DM water using microwave power (800 watt) at 200-260°C, 60 Bar pressure wherein colloidal silica gets converted into reactive silica in closed system. Detailed description of the Invention Based on this principal that at high temperature and pressure colloidal silica gets converted into reactive silica, a clean method to determine colloidal silica was devised. In the first part of the study different methods in use for colloidal silica measurement were compared and it was observed that in HF-Boric acid method results were inconsistent, conversion from colloidal to reactive silica was not complete and some time solutions get turbid. There was no improvement in he silica concentration before and after the treatment when the samples were subjected to bomb digestion. Though there was some conversion in Alkali molybedate method but heating in open conditions causes loss of sample by evaporation, so results were erratic. Finally to utilize the fact that colloidal silica gets converted into reactive silica at elevated temperature and pressure conditions, water samples were digested in Microwave digester high temperature & pressure conditions (60 Bar, 200-250 °C). The samples from raw water and DM water were analysed for silica by conventional method (ANSA) before and after the digestion in microwave digester. The difference in the results were taken as colloidal silica. Results obtained by this method were consistent, complete conversion was there and it was a simple & clean method as no hazardous chemicals were used. A novel method for the analysis of colloidal silica has been established. The basic approach was the conversion of colloidal silica into reactive silica and there analysis as per standard methods using UV spectrophotometery. The water samples were subjected to microwave power (Model: Multiwave3000; Perkin Aimer/Anton Par) at temperature; upto-260°C, pressure in Vessel; up-to 60 bar and 800 wait. Samples were digested for the duration of 30-60 minutes (till the attainment of temperature above 200°C). The method was validated from the analysis of Raw water to steam cycles from two plants. The results were also compared with existing method for colloidal silica. To ensure heating in closed system at high pressure Microwave digester was used for conversion of colloidal to reactive silica: Temperature: upto-260 °C Pressure in Vessel: 60 bar, Watt: 800 DM water samples were subjected to microwave radiations followed by spectrophotometric analysis. (Table Removed) Clean method, Consistent results, no use of hazardous chemical. We Claim 1. A novel clean process to determine colloidal silica in raw and DM water using microwave power (800 watt) at 200-260°C, 60 Bar pressure wherein colloidal silica gets converted into reactive silica in closed system. 2. A novel clean process to determine colloidal silica in raw and DM water as described in claim 1, wherein silica before treatment and after treatment are as described and illustrated herein.

Documents:

96-del-2009-Abstract-14-08-2014.pdf

96-del-2009-abstract.pdf

96-del-2009-Claims-(14-08-2014).pdf

96-del-2009-claims.pdf

96-del-2009-Correspondence Others-(08-01-2013).pdf

96-del-2009-Correspondence Others-(11-10-2013).pdf

96-del-2009-Correspondence Others-(14-08-2014).pdf

96-del-2009-Correspondence Others-(23-01-2013).pdf

96-DEL-2009-Correspondence-Others-(03-08-2009).pdf

96-del-2009-Correspondence-Others-(24-09-2009).pdf

96-del-2009-correspondence-others.pdf

96-del-2009-description (complete).pdf

96-DEL-2009-Form-1-(03-08-2009).pdf

96-del-2009-Form-1-(14-08-2014).pdf

96-del-2009-form-1.pdf

96-del-2009-Form-18.pdf

96-del-2009-form-2.pdf

96-DEL-2009-GPA-(03-08-2009).pdf

96-DEL-2009-Petition-137-(03-08-2009).pdf