Investigation of the components nature and concentration influence on carbon dioxide equilibrium in the system CaCl2-Na2CO3-NaOH-H2O by potentiometric titration

Abstract

The modern thermal power plants equipment requires strict deposits control on the surfaces. Such deposits are formed from impurities entering the cycle with water, the amount of which has significantly increased at modern powerful thermal power plants. At the modern level of the coolant water treatment, it is possible to exclude most of the impurities responsible for salt deposition. Analysis of various types of the sediments has shown that carbonate deposits are an integral part of them. Modern research methods (potentiometric titration in combination with methods of mathematical modelling) for carbonate, silicate, phosphate water systems have shown the existence of phase-unstable states leading to salt deposition during the coolant circulation. In this article, the carbonate system CaCl2-Na2CO3-NaOH-H2O was studied by potentiometric titration with a glass indicator electrode. The influence of the components nature (Li2CO3, Na2CO3, Ca2CO3, LiOH, NaOH, KOH, CaCl2, MgCl2) and the conditions for the existence of phase-unstable systems with varying concentrations of these components were studied. It is known that organic phosphonates are effective inhibitors of deposits in the carbonate system. In this paper, the action of two compounds of the specified class is considered. The concentration limits of their inhibitory action have been determined.