Salt Solubility and Saturated Electrical Conductivity Data for Water + Monoethylene Glycol + NaCl in a Wide Temperature Range

Abstract

Monoethylene glycol (MEG) is used to prevent hydrate formation in subsea pipelines of natural gas production. MEG is recovered at an offshore regeneration unit. Sodium chloride is the predominant salt in the water−MEG streams. Thus, knowledge of NaCl solubilities in the process conditions is relevant for the design and operation of a MEG regeneration unit. Six isotherms of NaCl solubility were measured (76 data points) from T = (293.15 to 403.15) K in the whole solvent concentration range. The analytical method for salt solubility was based on the reproducibility of the concentration of two successive samples. Density measurements were accurately applied for these analyses. The temperature dependence on NaCl solubility is relatively weak. A reverse behavior with increasing temperature was observed for MEG contents higher than 90 wt %. Salt solubilities were successfully correlated with Redlich−Kister expansion (AADwNaCl = 0.0006 and ΔwNaCl = 0.47%). Electrical conductivity of NaCl - saturated solutions were measured (44 data points) at T = (293.15 to 363.15) K and correlated with a semiempirical model. A large difference in electrical conductivity for the two solvents was observed. The correlation adequately represented the data set (AADκ = 5.67 mS·cm−1 and Δκ = 5.94%). NaCl solubilities and electrical conductivities were accurately determined and are useful for the MEG regeneration process