Modelagem termodinâmica da precipitação de halita e silvina em soluções aquosas

Abstract

The precipitation of salts is an important topic of study in petroleum extraction due to the possibility of incrustations of them in the pipes that may end up reducing or even preventing the production. The losses linked to the incidence of inlay reach, on a global scale, billions of dollars per year in the petroleum industry and, thus, the study about the favorable conditions for precipitation and the formation of these deposits are prominent in the petroleum and gas production. Consequently, it is necessary to determine under which thermodynamic circumstances this precipitation phenomenon occurs, that is, at what temperature for a given salt concentration, it begins to precipitate. In this study, the solid-liquid balance of H2O + NaCl (halite) and H2O + Kcl (silvine) was modeled thermodynamically. The method used to determine the activity coefficient was UNIQUAC + Pitzer-Debye-Huckel, due to its high efficiency in non-ideal systems and the limitation of other methods in solid-liquid equilibrium systems. The model accurately represented the precipitation of salts with a temperature between 298,15 and 353,15 K and electrolyte concentration until saturation. This model should be useful for process modeling and simulation of aqueous electrolyte solutions involving NaCl and Kcl.