"Calcium chloride solubility in mixtures of water and monoehtylene glycol"
Calcium Chloride, solubility, MEG, water, density, conductivity.
In the oil and gas industry, the hydrates formation is one of the issues related to the production in natural gas wells. One of the most employed techniques to avoid the hydrates formation is the injection of inhibitors compounds, like the monoethylene glycol (MEG) into the well. However, the MEG stream returns to the surface impregnated with water and many salts coming from the rock sediments. Then, the MEG must be regenerated to assure the process environmental and economic viability. In order to optimize the operationals conditions of the reclamation process, this work aimed to determine the solubility of the salt calcium chloride in aqueous mixtures of MEG, in the temperatures of 25 and 50°C. The proposed methodology had the intent of obtaining solubility data by using indirect proprieties, the density and the conductivity. Therefore, the performed analyzes were, mainly, densimetry, condutimetry, and beyond them, thermogravimetry and Karl Fischer titration to determine the reagents moisture content. Observing the developed curves od density and conductivity versus calcium chloride concentration, it was detected the motone behavior for the density in function of the salt concentration, while the conductivity showed a no-monotone behavior. In the solubility experiments, the taken samples were utilized to determine the concentration based on the density data. The developed isotherms illustrate the solubility versus MEG concentration in the solvents mixture. The isotherms analyze make it possible to notice the slight relevance of the salting-out effect, caused by the MEG presence in the solvent, until the concentration of 50% salt –free MEG. From that point, there are changes in the inclination of both isotherms and the solubility decreases more pronouncedly. In terms of the temperature increase, the calcium chloride solubility showed a positive effect. Setchenov equation and the UNIQUC model, together with thermochemical data, were applied to describe the experimental data. In the UNIQUAC approach, it was not considered the possible change in the formed solid phase.