Monitoring of CO₂ Absorption Solvent in Natural Gas Process Using Fourier Transform Near-Infrared Spectrometry

Abstract

The analytical methods for the determination of the amine solvent properties do not provide input data for real-time process control and optimization and are labor-intensive, time-consuming, and impractical for studies of dynamic changes in a process. In this study, the potential of nondestructive determination of amine concentration, CO2 loading, and water content in CO2 absorption solvent in the gas processing unit was investigated through Fourier transform near-infrared (FT-NIR) spectroscopy that has the ability to readily carry out multicomponent analysis in association with multivariate analysis methods. The FT-NIR spectra for the solvent were captured and interpreted by using suitable spectra wavenumber regions through multivariate statistical techniques such as partial least square (PLS). The calibration model developed for amine determination had the highest coefficient of determination (R2) of 0.9955 and RMSECV of 0.75%. CO2 calibration model achieved R2 of 0.9902 with RMSECV of 0.25% whereas the water calibration model had R2 of 0.9915 with RMSECV of 1.02%. The statistical evaluation of the validation samples also confirmed that the difference between the actual value and the predicted value from the calibration model was not significantly different and acceptable. Therefore, the amine, CO2, and water models have given a satisfactory result for the concentration determination using the FT-NIR technique. The results of this study indicated that FT-NIR spectroscopy with chemometrics and multivariate technique can be used for the CO2 solvent monitoring to replace the time-consuming and labor-intensive conventional methods.

Enhancement of CO2 Absorption Process Using High-Frequency Ultrasonic Waves

“…The amine concentration and loading were determined by using the titration method. For amine concentration determination, the amine samples were titrated with 0.5 N hydrochloric acid (HCl) [43]. A total of 5 g of amine samples were mixed with 95 mL of distilled water and stirred at 400 rpm using a magnetic stirrer.…”

“…where V HCl (mL) is the volume of HCl used to titrate the sample in mL, N HCl is the normality of the HCl solution and W s (g) is the weight of the sample. For amine loading determination, the amine samples were titrated with 0.5 N potassium hydroxide (KOH) [43]. A total of 20 g of the amine sample was weighed.…”

Numerical Modeling and Economic Analysis of Ultrasonic-Assisted CO2 Absorption Process for Offshore Application

“…The titration method was used to determine the amine concentration and loading. For amine concentration determination, the samples were titrated with 0.5 N hydrochloric acid (HCl) [41]. 95 mL of distilled water was mixed with 5 g of amine sample and stirred at 400 rpm using the magnetic stirrer.…”

“…where V HCl (mL) was the volume of HCl used to titrate the sample, N HCl was the normality of the HCl solution, and W s (g) is the weight of the sample. For amine loading determination, the amine samples were titrated with 0.5 N potassium hydroxide (KOH) [41]. First, 125 mL of methanol was measured, and its pH was adjusted to 11.2 by adding a few drops of 0.5 N KOH.…”

“…The weight of the amine sample, the pH of the mixture before and after titration, and the volume of 0.5 N KOH used in the titration were recorded. The concentration (wt%) of acid gas in the amine solution was determined using the formula [41]:…”