TITLE:
Refractometric Determination of Thermodynamic Hydrate Inhibitor Concentrations under Variable Operating Conditions: A Physicochemical Evaluation
AUTHORS:
Tombari Ransome Mbooh, Ogbonna Friday Joel, Nuka Dumle Nwiabu, Joe Emmanuel Akhagbeme
KEYWORDS:
Gas Hydrate, Refractive Index Measurement, Hydrate Inhibitors Optimization, Inhibitor Actual Concentration, Flow Assurance
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.16 No.4,
September
3,
2026
ABSTRACT: Accurate optimization of hydrate inhibition requires knowledge of the actual inhibitor concentration retained in the aqueous phase under operating conditions. This study applied refractometry to determine effective concentrations of monoethylene glycol (MEG) and methanol (MeOH). Calibration curves were developed using known weight-percent solutions, yielding strong correlations between refractive index and concentration (R2 > 0.98). Samples extracted from a mini-hydrate flow loop at varying pressures confirmed a linear relationship between the input dosage and the actual concentration (R2 > 0.99). MEG retained ~95% of its input dosage, while MeOH retained ~90%. Concentrations decreased slightly with lower operating pressures, reflecting volatility and gas-phase partitioning effects. These findings demonstrate refractometry as a reliable, cost-effective method for real-time monitoring and optimization of hydrate inhibitors.