STP742

    Continuous Conductivity Monitoring of Anions in High-Purity Water

    Published: Jan 1981


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    Abstract

    This paper describes the continuous and accurate monitoring of electrical conductivity of anions in feedwater and turbine condensate by two new instruments, a Feedwater Analyzer and a Condensate Reboiler. As has been pointed out, the advantages of this testing technique are that carbon dioxide and ammonia interferences are eliminated, the conductivity is measured at constant temperature, and increased sensitivity to anions is attained by measuring the conductivity of anions in the acidic and more conductive form. Design changes in this equipment have made possible more accurate conductivity measurement in the range of 0.01 to 0.1 S/cm at atmospheric boiling water temperature. This results in increased sensitivity of measurement, so that 1 to 5 ppb of Cl + SO=4 can be determined.

    An advantage is shown in that low levels of 0.01 to 0.05 mg/litre of carbon dioxide (CO2) have a lower conductivity at atmospheric boiling temperature than at room temperature (25°C). More accurate cation conductivity results may therefore be expected by measurement at atmospheric boiling water temperature than by degassing with nitrogen.

    By including pH measurements along with conductivity and temperature measurements at room temperature, it is shown that ammonia and carbon dioxide of this two-component system may be calculated. Calculated ammonia and carbon dioxide results are shown not to be appreciably affected by the presence of 10 ppb chloride or more. The presence of 100 ppb total organic carbon (TOC) (as acetic acid) in steam condensate is also shown to have a negligible effect on the calculated ammonia and carbon dioxide results above 3 to 4 μS/cm.

    Keywords:

    feedwater analysis, condensate analysis, newly designed instruments, improved cation conductivity accuracy, ammonia, carbon dioxide, pH, conductivity, temperature, power plants, instrumentation, water quality


    Author Information:

    Lane, RW
    Principal scientist, principal chemist, and chemist, Illinois Institute of Natural Resources, State Water Survey Div., Urbana, Ill.

    Sollo, FW
    Principal scientist, principal chemist, and chemist, Illinois Institute of Natural Resources, State Water Survey Div., Urbana, Ill.

    Neff, CH
    Principal scientist, principal chemist, and chemist, Illinois Institute of Natural Resources, State Water Survey Div., Urbana, Ill.


    Paper ID: STP28287S

    Committee/Subcommittee: D19.08

    DOI: 10.1520/STP28287S


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