A Study of Mass Transfer Kinetics of Carbon Dioxide in (Monoethanolamine + Water) by Stirred Cell

AbstractThe gas phase resistance in a stirred cell was investigated to understand and avoid its influence on the measurement of the reaction kinetics. To validate the influence of gas phase resistance and the experimental conditions of pseudo first order reaction for Monoethanolamine (MEA) + CO2 system, low CO2 partial pressure under various inert gas pressure were employed for CO2 the absorption into 0.5, 1, 3 and 3.6M MEA solutions with H2O and ethyleneglycol as solvents, respectively. The absorption was investigated with the stirred cell based on a fall-in-pressure technique

Process intensification for post combustion CO₂ capture with chemical absorption: a critical review

The concentration of CO₂ in the atmosphere is increasing rapidly. CO₂ emissions may have an impact on global climate change. Effective CO₂ emission abatement strategies such as carbon capture and storage (CCS) are required to combat this trend. Compared with pre-combustion carbon capture and oxy-fuel carbon capture approaches, post-combustion CO₂ capture (PCC) using solvent process is one of the most mature carbon capture technologies. There are two main barriers for the PCC process using solvent to be commercially deployed: (a) high capital cost; (b) high thermal efficiency penalty due to solvent regeneration. Applying process intensification (PI) technology into PCC with solvent process has the potential to significantly reduce capital costs compared with conventional technology using packed columns. This paper intends to evaluate different PI technologies for their suitability in PCC process. The study shows that rotating packed bed (RPB) absorber/stripper has attracted much interest due to its high mass transfer capability. Currently experimental studies on CO₂ capture using RPB are based on standalone absorber or stripper. Therefore a schematic process flow diagram of intensified PCC process is proposed so as to motivate other researches for possible optimal design, operation and control. To intensify heat transfer in reboiler, spinning disc technology is recommended. To replace cross heat exchanger in conventional PCC (with packed column) process, printed circuit heat exchanger will be preferred. Solvent selection for conventional PCC process has been studied extensively. However, it needs more studies for solvent selection in intensified PCC process. The authors also predicted research challenges in intensified PCC process and potential new breakthrough from different aspects

Gas treating: absorption theory and practice

Gas Treating: Absorption Theory and Practice provides an introduction to the treatment of natural gas, synthesis gas and flue gas, addressing why it is necessary and the challenges involved.  The book concentrates in particular on the absorption-desorption process and mass transfer coupled with chemical reaction. Following a general introduction to gas treatment, the chemistry of CO2, H2S and amine systems is described, and selected topics from physical chemistry with relevance to gas treating are presented. Thereafter the absorption process is discussed in detail, column hardware is explai

Ultrasound intensify CO2 desorption from pressurized loaded monoethanolamine solutions. II. Optimization and cost estimation

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Density Measurements of Unloaded and CO₂‑Loaded 3‑Amino-1-propanol Solutions at Temperatures (293.15 to 353.15) K

The first part of this work presents experimental density data of aqueous 3-amino-1-propanol (3A1P) solutions at different compositions and temperatures of (293.15 to 353.15) K. It was found that densities decreased with increasing temperatures and were concentration dependent. Excess molar volumes of aqueous 3A1P were also established. Five different methods were compared for correlating density data of unloaded 3A1P solutions. In the second part of this work, densities of CO₂-loaded solutions were measured at 0.1 and 0.5 mass fractions of 3A1P at increasing temperatures and CO₂-loadings. Two different models were used to regress these experimental data. The suitability of these methods to represent densities of unloaded and CO₂-loaded 3A1P solutions is evaluated

Measurements and Correlations of Diffusivities of Nitrous Oxide and Carbon Dioxide in Monoethanolamine + Water by Laminar Liquid Jet

The molecular diffusivities of nitrous oxide (N₂O) with aqueous monoethanolamine (MEA) solutions up to 12 M were studied over a temperature range from 298.15 to 333.15 K under atmospheric pressure using a laminar liquid jet absorber. The diffusivities of CO₂ in aqueous MEA solutions were calculated by the “N₂O analogy” method. A simple and effective thermal control technique was used to control the temperatures of gas and liquid in the laminar liquid jet absorber. The rates of absorption were determined by measuring the flow of gas needed to replace the gas absorbed. The results showed that the diffusivities of both N₂O and CO₂ into aqueous MEA solution decrease with the increase of the concentration of MEA, and increase with an increase of the temperature of the solution. The relationship between the diffusivity and the viscosity of the solution roughly agrees with the modified Stokes–Einstein equation, but an exponent mathematical model was employed to simulate the diffusivity data and shows a better agreement between data and model for the diffusivity of N₂O and CO₂ in the monoethanolamine + water system

Determination and Measurements of Mass Transfer Kinetics of CO₂ in Concentrated Aqueous Monoethanolamine Solutions by a Stirred Cell

The gas–liquid reaction rate was determined with a stirred cell from the fall in pressure and the reaction rate constant was determined by two data treatment methods, viz. a “differential” and an “integral” method. The liquid-side mass transfer coefficient without chemical reaction in the stirred cell reactor was determined via the pressure drop method. The kinetics of the reaction of carbon dioxide with aqueous monoethanolamine (MEA) solutions over a wide concentration range from 0.5 to 12 M at a temperature range from 298.15 to 323.15 K were studied using a stirred cell absorber with a plane gas–liquid interface. Low CO₂ partial pressure (3–4 kPa) was employed to satisfy the criterion for a pseudo-first-order reaction. Very low inert gas pressures of N₂ and solution vapor were kept, and the stirrer was sped up to reduce the gas-phase resistance. The results showed that the investigated reactions took place in the pseudo-first-order fast reaction regime. The reaction rate constant obtained for MEA with CO₂ at 298.15 K agrees with literature. The reaction activation energy (<i>E</i>_a) of aqueous MEA + CO₂ is 44.89 kJ mol^–1, and the pre-exponential factor value is 4.14 × 10¹¹. The enhanced mass transfer coefficient in the liquid phase, <i>k</i>_L<i>E</i>, initially increases with the concentration of MEA solutions but decreases when the molarity of MEA is higher than 8 M

Free Energies of Activation for Viscous Flow of Different Amine Mixtures in Post Combustion CO2 Capture

The viscosity of ternary mixtures of N-methyldiethanol amine (MDEA) + monoethanol amine (MEA) + H2O, Nmethyldiethanol amine (MDEA) + diethanol amine (DEA) + H2O and 2-amino-2-methyl-1-propanol (AMP) + diethanol amine (DEA) + H2O were correlated using Eyring’s viscosity model based on absolute rate theory. The correlations were capable of representing viscosity data within AARD 1.9%, 1.4% and 2.1% for the mixtures MDEA + MEA + H2O, MDEA + DEA + H2O and AMP + DEA + H2O respectively. These accuracies are acceptable in engineering calculations. The excess properties of volume , viscosity and free energy of activation for viscous flow Δ∗ were studied to understand the intermolecular interactions in the mixtures. The study shows that all mixtures have a negative sign for , and a positive sign for Δ∗. This indicates weak intermolecular interactions in mixtures compared to the pure liquids and strong molecular attractions like H-bonds in the mixtures.publishedVersio

Physical Properties of MEA + Water + CO2 Mixtures in Postcombustion CO2 Capture: A Review of Correlations and Experimental Studies

The knowledge of physicochemical properties of a mixture of amine, water, and CO2 is beneficial in evaluating the postcombustion CO2 capture process and process equipment design. This study reviews the literature of density, viscosity, and surface tension measurements with the evaluated measurement uncertainties and proposed correlations for monoethanol amine (MEA), water, and CO2 mixtures. Adequate research has been performed to measure and develop correlations for pure MEA and aqueous MEA mixtures, but further studies are required for CO2-loaded aqueous MEA mixtures. The correlations fit measured properties with an acceptable accuracy, and they are recommended to use in process equipment design, mathematical modelling, and simulations of absorption and desorption

Density, viscosity and free energy of activation for viscous flow of CO2 loaded 2-amino-2-methyl-1-propanol (AMP), monoethanol amine (MEA) and H2O mixtures

This work presents an experimental study of densities and viscosities of aqueous AMP (2-amino-2-methyl-1-propanol) + MEA (monoethanol amine) + H2O solutions with and without CO2. Amine concentrations were at AMP to MEA mass % ratios of 21/9, 24/6, 27/3 by maintaining 70 mass % of H2O. Density measurements were performed in a temperature range from 293.15 K to 343.15 K and viscosity was measured at temperatures from 293.15 K to 363.15 K. The excess molar volume was determined from experimental density data. A Redlich-Kister type polynomial of excess molar volume was adopted to represent the density of unloaded aqueous mixtures. For CO2 loaded solutions, Setschenow-type correlations and modified Weiland's density and viscosity correlations were used to fit density and viscosity data. Eyring's viscosity model was used to evaluate free energy of activation for viscous flow of mixtures through measured density and viscosity data. The volumetric and viscometric properties of aqueous mixtures were analyzed through the molecular structure and interactions. A correlation was proposed for the free energy of activation of viscous flow to represent viscosity of CO2 loaded solutions. The results reveal that the proposed correlations for the density and viscosity of mixtures are in good agreement with measured data