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File Name: Conductivity.pptFeb 2001 Conductivity Theory Applied to Proper Hardware Selection.

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Presentation on theme: "File Name: Conductivity.pptFeb 2001 Conductivity Theory Applied to Proper Hardware Selection."— Presentation transcript:

1 File Name: Conductivity.pptFeb 2001 Conductivity Theory Applied to Proper Hardware Selection

2 File Name: Conductivity.pptFeb 2001 Conductivity Measurement Used to Measure and Control the Percent Concentration of Acids, Bases and Salts in Solution Measures Total Concentration Not Ion Specific May be Used to Determine the Dominant Chemical

3 File Name: Conductivity.pptFeb 2001 Electrolytes Acids Substances which ionize in solution and produce hydrogen ions, H + Hydrochloric Acid (HCl) dissociates into H + + Cl - Bases Substances which ionize in solution and produce hydroxide ions, OH - Sodium Hydroxide, NaOH, dissociates into Na + + OH - Salts Substances which ionize in solution and produce neither hydrogen or hydroxide ions Sodium Chloride, NaCl, dissociates into Na + + Cl -

4 File Name: Conductivity.pptFeb 2001 Typical Conductivity Values

5 File Name: Conductivity.pptFeb 2001 Conductivity Measurement Units of Measurement U.S. Units = Micromhos/cm International Units = MicroSiemens/cm 1.0 S/cm = 1,000 mS/cm = 1,000,000 uS/cm umho/cm = uS/cm Conductivity is the Reciprocal of Resistance 1.0 MicroSiemen/cm = 1,000,000 Ohms/ - cm 1,000,000 MicroSiemens/cm = 1.0 Ohm/ - cm

6 File Name: Conductivity.pptFeb 2001 Conductivity Measurement High Purity Water Applications Power & Semiconductor Manufacturing Conductivity Measured as Resistivity in MegOhms/cm Pure Water = Meg Ohms/ - cm = uS/cm Water & Water Treatment Applications Industrial Boilers & Cooling Towers Conductivity Measured in Total Dissolved Solids (TDS)

7 File Name: Conductivity.pptFeb 2001 Conductance of Common Acids, Bases and 25 o C

8 File Name: Conductivity.pptFeb 2001 Conductivity Measurement Each Acid, Base and Salt has Its Own Temperature Vs. Concentration Curve The Temperature Slope Varies for Different Chemicals Acids 1.0% - 1.6% / o C Natural Waters 2.0%/ o C Bases > %/ o C High Purity Water 2.3% - 7.3%/ o C

9 File Name: Conductivity.pptFeb 2001 Specific Conductivity of Sulfuric Acid

10 File Name: Conductivity.pptFeb % Sulfuric Acid Solution

11 File Name: Conductivity.pptFeb 2001 Change in Temperature Slope/ o C

12 File Name: Conductivity.pptFeb 2001 Conductivity Measurement Apply an AC Voltage to Two Electrodes of Exact Dimensions Acids, Bases and Salts (NaCl) Dissolve in Solution and Act as Current Carriers The Current Flow is Directly Proportional to the Total Dissolved Solids in Solution The Physical Dimensions of a Conductivity Electrode are Referred to as the Cell Constant Cell Constant is Length/Area Relationship Distance Between Plates = 1.0 cm Area of Each Plate = 1.0 cm x 1.0 cm Cell Constant = 1.0 cm - 1 Cell Constant Used to Determine the Measuring Range of the Analyzer Acts as Multiplier Used to Calibrate Analyzer Determined Using NBS Standards Can be NIST Traceable Na + Cl -

13 File Name: Conductivity.pptFeb 2001 Four Electrode Conductivity Cells Measures Current and Voltage Drop Current Increases with an Increase in Voltage Drop Across Electrodes Compensates for Minor Coatings on Conductivity Electrodes Used for Higher Range Measurement V

14 File Name: Conductivity.pptFeb 2001 Inductive Conductivity Also Known as Toroidal and Electrodless Principle of Measurement Two Sealed Wire Wound Coils Electrically Coupled by Solution Conductivity Advantage No Electrodes Exposed to the Measured Solution Not Affected by Coating Disadvantage +- 10% Accuracy High Range Measurement Only > 100 uS/cm

15 File Name: Conductivity.pptFeb 2001 RO Unit Reverse Osmosis Unit Acid Feed Feed Water Tank Conductivity Transmitter pH Transmitter Feed Water Waste

16 File Name: Conductivity.pptFeb 2001 Demineralizer Unit Cation Bed Mixed Bed Anion Bed To Water Storage Acid RegenerationCaustic Regeneration Conductivity Transmitter Conductivity Transmitter Conductivity Transmitter Conductivity Transmitter Conductivity Transmitter

17 File Name: Conductivity.pptFeb 2001 TypeNumber Conductivity4 Concentration2 pH1 Total7 Usually 2 per generation unit (make up & polisher) and built in pairs Total X 4 = 28 Analyzers per Unit Two Units Built at a time = 56 Analyzers Power Utilities Average Number of Analyzers for Each Demin Unit

18 File Name: Conductivity.pptFeb 2001 Analyzer Type Number pH5 Specific Conductivity6 Cation Conductivity11 Condensate Analyzer1 Total23 Usually Units Built in Pairs = 46 Analyzers Power Utilities Average Number of Analyzers Per Generating Unit

19 File Name: Conductivity.pptFeb 2001 Boiler Blowdown and Condensate Return Lines Steam Drum Heat Exchanger Condensate Return Top Blowdown Line Conductivity Transmitter Blowdown Valve Steam Header Conductivity Transmitter Waste Mud Drum Manual Blowdown Valve Do Not Automate ! Feed Water Tank Flash Tank

20 File Name: Conductivity.pptFeb 2001 Clean in Place (CIP) Conductivity Transmitter Caustic Dilution Tank Solution Recovery Process Vessels Water Conductivity Transmitter CIP Return Lines Caustic


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