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.
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