Development of an Online Monitoring Method of a CO₂ Capture Process

Abstract

One possible way to reduce our carbon footprint is using postcombustion capture (PCC) processes to remove CO 2 from flue gases. Because of the highly dynamic characteristics of such processes, real-time performance monitoring is a very complex task. This paper presents a method for monitoring the concentrations of CO 2 , SO x , and a CO 2 capturing agent (β-alanine) during a process in a PCC pilot plant. A partial least-squares (PLS) model was built to estimate these concentrations from Fourier transform infrared (FTIR) spectra of the capturing solvent during processing in a model PCC plant. The model predicts the species concentrations to within 0.05 mol/L, provided that the concentrations stayed within the calibration window of the model. Next to that, it is paramount that the solutions used for model calibration consist of the same solution matrix as the real process medium. The model was eventually used to monitor an emulated PCC process online during 24 h of processing. This demonstrated that events such as saturation of the capturing agent with CO 2 , water replenishment, and switching to safety protocols can be followed accurately. The combination of an FTIR spectrometer and a PLS model can be used to extract process information in real-time.

ATR-FTIR Model Development and Verification for Qualitative and Quantitative Analysis in MDEA–H2O–MEG/TEG–CO2 Blends

“…The four-component system models were able to predict the actual concentrations with >95% accuracy except for boundary regions (1-10 wt% and 90-99 wt%). A similar precision was obtained by Geers et al [21] for three-component systems; attaining the same precision for four-component systems confirms the accuracy of the model. A periodical pattern can be observed in the results of weight residuals as a function of actual wt% because the total sum of wt% remained 100 for each sample in all systems.…”

“…It requires calibration and validation datasets, which cover a full range of process gas pressures and amine concentrations, however, this combination does not provide accurate results outside the calibration and validation dataset [19]. The FTIR and PLS combination has been used successfully to extract process information data from the CO 2 absorption system [20] and also from the simultaneous absorption of the CO 2 and SO 2 in a pilot plant [21]. Furthermore, FTIR was used to measure both inorganic and organic compounds in amine-based post-combustion carbon capture (PCCC) in flue gas [22][23][24] and also in an ammonia-based CO 2 capture process [25].…”

Inline Monitoring of CO2 Absorption Processes Using Simple Analytical Techniques and Multivariate Modeling

“…In order to enable the real-time monitoring of both the solvent concentration and acid gas loading, attempts have been made to apply Fourier transform infrared (FTIR) spectroscopy in combination with a multivariate analysis method, also known as chemometrics [7][8][9]. Using FTIR for the in situ analysis of aqueous alkanolamine solutions has first been applied aiming at more accurate vapor-liquid equilibrium data for such systems.…”

“…In [7], it is proven in a laboratory environment that the increase in CO 2 concentration in aqueous solutions of NaOH, MEA, AMP, and MDEA can be monitored using FTIR. The most extensive work done in this research direction is described in [8], focusing at an equimolar solution of b-alanine and potassium hydroxide (K-b-ala). In addition to the concentrations of K-b-ala and CO 2 , absorbed SO 2 and NO 2 were also included in the analysis.…”

Online composition analysis of phase separation solvent for carbon dioxide capture using ATR‐FT‐IR

“…Attempts to determine the liquid phase composition using Raman and Fourier transform infrared (FT-IR) spectroscopy have been performed recently for a small number of aqueous amine systems. [18][19][20][21][22] Although Raman spectroscopy was also examined as an online monitoring method, only FT-IR spectroscopy exhibited the ability to resolve the spectra for both laboratory and pilot plant samples. [19] The heat generated by irradiating the Raman beam onto the sample caused localized inconsistencies in CO 2 species, which was a disadvantage of this method.…”