Thermodynamic Data For The Assessment Of SG Blowdown Demineralizers Performance

摘要

Steam Generator BlowDown (SGBD) system reduces corrosion products accumulation leading to fouling or tube support plates (TSP) blockage. The evacuation of corrosion products at the SGBD may significantly be improved by the use of dispesant product like PolyAcrylic Acid (PAA), introduced in the SG. To study the behaviour of PAA on SGBD, a R&D program has been set up in order to get useful sorption thermodynamic data for the assessment of the blowdown effluent demineralizers performance. These purification media are a series of cation and anion exchange resins beds. The efficacy of demineralizers has been tested in several media: ammonia, ethanolamine, morpholine for sodium, acetate and sulphate removal.Besides analytical on-line control of the effluent, it is useful to be able to predict the migration rate of the contaminants through the porous beds by reactive transport calculations. This prediction requires the knowledge of the concentrations of the resins adsorption sites and the thermodynamic constants(corrected selectivity coefficients) characterising the ion-exchange equilibria taking place between the flowing interstitial liquid and the resins. These data have been determined under well-designed batch experimental conditions, using radio-isotopes and radio-labelled compounds for distribution coefficient measurements, and ion-chromatography for non-radioactive solutes analysis. In particular, ~(14)C-labelled PAA has been synthesized and involved in the study of this constituent.