Alkali-nitrate interactions in water-ethylene-glycol mixtures. Conductometric measurements at 25°C

A comprehensive thermodynamic model has been developed for calculating thermodynamic and transport properties of mixtures containing monoethylene glycol (MEG), water, and inorganic salts and gases. The model is based on the previously developed mixed-solvent electrolyte (MSE) framework, which has been designed for the simultaneous calculation of phase equilibria and speciation of electrolytes in aqueous, nonaqueous, and mixed solvents up to the saturation or pure solute limit. In the MSE framework, the standard-state properties of species are calculated from the Helgeson–Kirkham–Flowers equation of state, whereas the excess Gibbs energy includes a long-range electrostatic interaction term expressed by a Pitzer–Debye–Hückel equation, a virial coefficient-type term for interactions between ions and a short-range term for interactions involving neutral molecules. Model parameters have been established to reproduce the vapor pressures, solubilities of solids and gases, heat capacities, and densities for MEG + H2O + solute systems, where the solute is one or more of the following components: NaCl, KCl, CaCl2, Na2SO4, K2SO4, CaSO4, BaSO4, Na2CO3, K2CO3, NaHCO3, KHCO3, CaCO3, HCl, CO2, H2S, and O2. In particular, emphasis has been put on accurately representing the solubilities of mineral scales, which commonly appear in oil and gas environments. Additionally, the model predicts the pH of mixed-solvent solutions up to high MEG contents. On the basis of speciation obtained from the thermodynamic model, the electrical conductivity of the MEG + H2O + NaCl + NaHCO3 solutions is also calculated over wide ranges of solvent composition and salt concentration. Additionally, associated models have been established to compute the thermal conductivity, viscosity, and surface tension of aqueous MEG mixtures.

Section: Resultsmentioning

confidence: 99%

Section: Evaluation Of Model Parametersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ethylene Glycol and Its Mixtures with Water and Electrolytes: Thermodynamic and Transport Properties

Wang

Kosinski

Anderko

et al. 2013

“…Specifically, the Walden’s product, ηΛ o was calculated from measurements of the limiting conductance, Λ ο , of calcium ion solutions and of the viscosity, η, over a range of MEG–water mixtures (10–90%v/v MEG) (Supplement S3). This parameter shows the influence by the asymmetry of the co-ordination spheres which formed by the hydration of the CaCO 3 lattice ions.…”

Section: Resultsmentioning

confidence: 99%

Precipitation of Calcium Carbonate (CaCO₃) in Water–Monoethylene Glycol Solutions

Natsi

Rokidi

Koutsoukos

2019

The influence of monoethylene glycol (MEG) on the precipitation process of calcium carbonate at constant supersaturation, 25 °C, and pH 8.5 was investigated. MEG aqueous solutions supersaturated with respect to all calcium carbonate polymorphs were used since they are often encountered in oil production processes where they are used as a hydrate inhibitor. Both seeded and unseeded experiments were done in aqueous supersaturated calcium carbonate solutions containing MEG over the concentration range 0–80% v/v. The presence of MEG affected the induction times and the subsequent rates of precipitation in unseeded, spontaneous precipitation of calcium carbonate. At low values of the supersaturation ratio (SRcalcite = 77.62–15 135.61 or σcalcite = 7.81–122) and for MEG concentrations in the range 30–80% v/v, the solutions were stable for 4 days. At lower than 30% v/v MEG concentrations, calcium carbonate precipitation took place past induction periods between 160 and 500 min. The morphological examination of the precipitates showed that in the presence of low MEG concentrations (10–20% v/v) the precursor vaterite was stabilized. The homogeneous nucleation and growth of calcium carbonate in the absence and in the presence of MEG was also investigated by the inoculation of stable supersaturated solutions with quartz and calcite seed crystals. In both cases nucleation and growth of calcium carbonate was significantly reduced with increasing MEG concentration in the solutions.

“…(E) Surface tension (σ): □, Ref ; △, Ref ; ○, Ref ; and ☆, Ref . (F) Dynamic viscosity (η): □, Ref ; △, Ref ; ⬠, Ref ; ×, Ref ; ☆, Ref ; and ○, Ref .…”

Section: Methodsmentioning

confidence: 99%

Simulation and Analysis of MEG Reclamation and Regeneration Unit in Offshore Natural Gas Plants

Moura-Neto,

Monteiro,

Pereira

et al. 2023

Monoethylene glycol (MEG) is applied to mitigate natural gas hydrate in subsea pipelines. MEG is injected into the wellheads and flows with reservoir fluids to the platform. MEG reclamation and regeneration are conducted, allowing the inhibitor reuse and thus minimizing operational costs and environmental impacts. Four process configurations were evaluated using OLI software, i.e., Full-Stream (FS) and Slip-Stream (SS) processes with and without atmospheric distillation. The operational conditions from the Mexilhaõ unit (Petrobras/BS) were applied. MEG recovery > 99% was obtained. Although the FS process demanded higher energy (22.3 GW•h −1 ), the achieved lean-MEG purity was also higher (97 wt %). Whereas the SS configuration required lower energy (≤18 GW•h −1 ) and resulted in higher water content in lean-MEG. Phase behavior and physicochemical properties were accurately described. Furthermore, MRU was successfully implemented in OLI demonstrating it to be valuable for process design and analyses, allowing the understanding of variables and regeneration efficiency.