Comparison of aqueous and non-aqueous alkanolamines solutions for carbon dioxide desorption in a microreactor

Anthropogenic climate change due to, among other causes, unhindered CO 2 emissions is a major concern worldwide. The postcombustion capture (PCC) process using a solvent, known as chemical absorption, is currently the most effective way to reduce CO 2 emissions from large point sources. However, high capital investment costs when using the conventional packed bed absorber/desorber technology and high energy requirements during solvent regeneration are the primary obstacles for its large-scale implementation. Different process intensification (PI) technologies to desorb CO 2 from the solvent have been introduced to mitigate the energy consumption compared to the conventional packed bed technology. This work reviews different technologies for intensification of CO 2 desorption. In this context, rotating packed beds, microreactors, and membrane contactors have been explored as potential alternatives to intensify the desorption because of their superior mass and heat transfer. Alternative energy sources like ultrasound and microwaves have also been used to improve the desorption performance of conventional equipments. PI can also be realized by using novel solvents with improved desorption kinetics in combination with intensification equipment. Thus in this review, a comprehensive assessment of different existing PI technologies based on regeneration energies and regeneration efficiencies relative to conventional technology is presented. The intensification of mass transfer for the different technologies is compared, and a new parameter, named the regeneration factor, is proposed to evaluate the performance of PI equipment. This study outlines the advances in process intensification of CO 2 desorption technologies to date and presents an overview of the merits and limits of all technologies.

Section: Conventional Packed Bed Technologymentioning

confidence: 99%

Process Intensification of CO₂ Desorption

Gecim

Ouyang

Roy

et al. 2022

“…9 At present, only a few reports have been published on the microreactor applications for CO 2 desorption. For instance, Aghel et al 151 compared the CO 2 desorptions of MEA, DEA, and A-MDEA in aqueous and nonaqueous (methanol) environments using microreactors. The authors highlighted that the desorption energy consumption could be reduced by 88.0% using microreactors compared to the conventional packed-bed contactors.…”

Section: Absorbent Concentrationmentioning

confidence: 99%

Recent Advancements on Hydrodynamics and Mass Transfer Characteristics for CO₂ Absorption in Microreactors

Pasha

Liu

Zhang

et al. 2022

Process intensification for CO 2 absorption using microreactors has received growing interest from both academia and industry because of their great ability to overcome the mass transfer resistance across the phases boundaries, giving rise to significant improvement in process efficiency. Mass transfer is strongly linked with two-phase flow patterns of CO 2 -absorbent in microreactors and, subsequently, overall volumetric mass transfer coefficient (ka) intensification relies on hydrodynamics, microreactor structures and applied absorbents. Reviewed literature on this subject indicated that the Taylor flow pattern, spiral and meandering microreactor structures, and primary and secondary amines absorbents were preferred to use for the CO 2 absorption in microreactors. Moreover, ka models developed through offline and online characterizations were presented to analyze the contribution of liquid film and bubble caps in mass transfer. Economic analysis was executed to assess the operating feasibility of microreactors at industrial scale throughputs of feed gas and absorbent. The results indicated that the capital expenses of microreactors were significantly higher than those of conventional absorbers because of their extensive number of units and complex design of flow distribution network requirements with high throughputs. However, microreactors exhibited lower operating expenditures than conventional absorbers because of their excellent transport characteristics. Finally, the persisting challenges and remarking conclusions are presented relating to the implementation of microreactors for CO 2 absorption.

“…Three organic groups are bonded to the nitrogen atom in the tertiary amines. The general formula for tertiary amines is R 3 N. Cyclic amines can be either secondary or tertiary amines having rings. − …”

Section: Introductionmentioning

confidence: 99%

Experimental Measurement and Thermodynamic Modeling of Methane Hydrate Dissociation Conditions in the Presence of Diglycolamine Aqueous Solution

Zoj

Javanmardi

Rasoolzadeh³

et al. 2022

Diglycolamine (DGA) aqueous solution is a sweetening agent that can be used in the natural gas processing plants to absorb acid gases. It can also be used for partial dehydration of natural gas. Since DGA has a hydroxyl functional group, it can connect with water molecules through hydrogen bonds, lowering the water activity and acting as a thermodynamic hydrate inhibitor. This work aims to investigate the impact of DGA aqueous solution on methane hydrate dissociation conditions. In this regard, a total of 39 dissociation data of methane hydrate in the presence of four DGA aqueous solutions (3.5, 10.0, 15.0, and 20.0 wt %) were experimentally measured in the pressure range of 3.49− 8.11 MPa and temperature range of (275.3 to 283.4) K. To do so, a stainless steel (SS-316) cell was utilized, and the isochoric pressure-search method was applied to measure the hydrate dissociation conditions. It was observed that by increasing the DGA concentration in aqueous solution, the inhibition effect of DGA is increased. The average hydrate dissociation temperature suppressions for 3.5, 10.0, 15.0, and 20.0 wt % DGA in aqueous solution are 0.5, 1.4, 2.2, and 3.5 K, respectively, which are very close to the inhibition strength of triethylene glycol (TEG), diethanolamine (DEA), and methyl diethanolamine (MDEA). In the thermodynamic modeling section, the van der Waals− Platteeuw (vdW−P) model is applied for the hydrate (solid) phase to calculate the methane hydrate dissociation conditions. Three activity coefficient models are employed for the aqueous phase: NRTL, UNIQUAC, and Wilson. Also, for the vapor/gas phase, three cubic equations of state (EoSs) are taken into account, namely, the Peng−Robinson (PR EoS), the Soave−Redlich−Kwong (SRK EoS), and the Valderrama−Patel−Teja (VPT EoS). All the models benefit from no parameter optimization. Among all the thermodynamic packages, the combinations of the (vdW−P + NRTL + VPT) and (vdW−P + UNIQUAC + PR) models are the best choices, with an average absolute deviation of 0.2 K in the determination of methane hydrate dissociation temperature.