Background. The presence of carbon dioxide in the steam of power boilers increases the corrosive activity of condensate and is characterized by an increase of the specific electrical conductivity of the H-cationic sample, often above the standard values. Chemical analysis of steam condensate samples for carbon dioxide content is difficult due to small values of its concentration. The removal of carbon dioxide from the condensate sample by degassing makes it possible to measure the concentration of salt impurities, which is an important indicator. It is standardized for almost all power boilers and can be represented by the value of the specific electrical conductivity of the degassed sample.
Materials and methods. Mathematical models to calculate the specific electrical conductivity of a degassed sample and the concentration of carbonic acid are based on equations of the theory of electrolyte solutions. Previously obtained expressions have been used to calculate the concentrations of impurities based on measurements of the specific electrical conductivity of direct and H-cationic samples, and pH in cooled samples.
Results. This paper presents a theoretical method to calculate the determination of a number of basic (standardized and diagnostic) quality indicators of steam of power boilers, including the concentration of carbon dioxide and the value of the specific electrical conductivity of the degassed sample. To compare calculated and measured concentrations of carbon dioxide, laboratory studies of extremely dilute model solutions of carbon dioxide have been carried out. The authors have shown the possibility to assess the reliability of calculated values of carbon dioxide concentrations in a condensate sample by experimental studies of the flow of carbon dioxide buffer solution using the industrial analyzer “Lider-APK” of “NPP Technopribor” (Moscow). An example to determine the concentration of carbon dioxide in a flow of the buffer solution using a calculation method is given. A comparison of the calculated data and the actual carbon dioxide content in the sample has been carried out.
Conclusions. The presented method to determine the carbon dioxide content includes methods to calculate the concentrations of salt components: chlorides and sodium sodium hydrogen carbonate and the specific electrical conductivity of a degassed sample. The presented method can be used for operational calculations when measuring specific electrical conductivity (c and cH) and pH in cooled samples, as well as for creation of a new analyzer of the quality of feed water, steam and condensate of power boilers and steam generators on the basis of “Lider-APK.