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Title: Water-Lean Solvents for Post-Combustion CO 2 Capture: Fundamentals, Uncertainties, Opportunities, and Outlook

Abstract

Capturing CO2 from the exhaust of coal-fired power plants is a daunting task, requiring selective removal from a dilute gas stream of millions of pounds per hour of a molecule that is considered thermodynamically and kinetically stable. There are commercial solvent technologies containing proprietary blends of aqueous amines such as Econamine FG+, KS-1, Oase® Blue, and Cansolv that may achieve this task, though only one of them has been deployed at scale, albeit in the natural gas industry.1 The Achilles’ heel of amine blends is the energy loss involved with regenerating the solvent, i.e., boiling and condensing millions of pounds of water per hour. This energy loss translates to a sizeable parasitic load on a coal-fired plant, requiring the plant to burn more coal to get back to its nameplate capacity.2 Unsurprisingly, a considerable amount of research has focused on the design of more efficient technologies to lessen this parasitic load. Liquid systems are the lowest hanging fruit from a time and cost perspective, as they have the potential to use aqueous amine infrastructure, with potential for more rapid ascent up the development ladder than porous solids or membranes.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1]
  1. Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1406697
Report Number(s):
PNNL-SA-122499
Journal ID: ISSN 0009-2665; KC0302020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemical Reviews; Journal Volume: 117; Journal Issue: 14
Country of Publication:
United States
Language:
English

Citation Formats

Heldebrant, David J., Koech, Phillip K., Glezakou, Vassiliki-Alexandra, Rousseau, Roger, Malhotra, Deepika, and Cantu, David C. Water-Lean Solvents for Post-Combustion CO 2 Capture: Fundamentals, Uncertainties, Opportunities, and Outlook. United States: N. p., 2017. Web. doi:10.1021/acs.chemrev.6b00768.
Heldebrant, David J., Koech, Phillip K., Glezakou, Vassiliki-Alexandra, Rousseau, Roger, Malhotra, Deepika, & Cantu, David C. Water-Lean Solvents for Post-Combustion CO 2 Capture: Fundamentals, Uncertainties, Opportunities, and Outlook. United States. doi:10.1021/acs.chemrev.6b00768.
Heldebrant, David J., Koech, Phillip K., Glezakou, Vassiliki-Alexandra, Rousseau, Roger, Malhotra, Deepika, and Cantu, David C. 2017. "Water-Lean Solvents for Post-Combustion CO 2 Capture: Fundamentals, Uncertainties, Opportunities, and Outlook". United States. doi:10.1021/acs.chemrev.6b00768.
@article{osti_1406697,
title = {Water-Lean Solvents for Post-Combustion CO 2 Capture: Fundamentals, Uncertainties, Opportunities, and Outlook},
author = {Heldebrant, David J. and Koech, Phillip K. and Glezakou, Vassiliki-Alexandra and Rousseau, Roger and Malhotra, Deepika and Cantu, David C.},
abstractNote = {Capturing CO2 from the exhaust of coal-fired power plants is a daunting task, requiring selective removal from a dilute gas stream of millions of pounds per hour of a molecule that is considered thermodynamically and kinetically stable. There are commercial solvent technologies containing proprietary blends of aqueous amines such as Econamine FG+, KS-1, Oase® Blue, and Cansolv that may achieve this task, though only one of them has been deployed at scale, albeit in the natural gas industry.1 The Achilles’ heel of amine blends is the energy loss involved with regenerating the solvent, i.e., boiling and condensing millions of pounds of water per hour. This energy loss translates to a sizeable parasitic load on a coal-fired plant, requiring the plant to burn more coal to get back to its nameplate capacity.2 Unsurprisingly, a considerable amount of research has focused on the design of more efficient technologies to lessen this parasitic load. Liquid systems are the lowest hanging fruit from a time and cost perspective, as they have the potential to use aqueous amine infrastructure, with potential for more rapid ascent up the development ladder than porous solids or membranes.},
doi = {10.1021/acs.chemrev.6b00768},
journal = {Chemical Reviews},
number = 14,
volume = 117,
place = {United States},
year = 2017,
month = 5
}
  • Here, we present here an overview of water-lean solvents that compares their projected costs and performance to aqueous amine systems, emphasizing critical areas of study needed to evaluate their performance against their water-based brethren. The work presented her focuses on bridging these knowledge gaps. Because the majority of water-lean solvents are still at the lab scale, substantial studies are still needed to model their performance at scale. This presents a significant challenge as eachformulation has different physical and thermodynamic properties and behavior, and quantifying how these different properties manifest themselves in conventional absorber-stripper configurations, or identifying new configurations that aremore » specific for a solvent’s signature behavior. We identify critical areas of study that are needed, and our efforts (e.g. custom infrastructure, molecular models) to predict, measure, and model these behaviors. Such findings are critical for determining the rheology required for heat exchanger design; absorber designs and packing to accommodate solvents with gradient changes (e.g. viscosity, contact angle, surface tension), and stripper configurations without direct steam utilization or water reflux. Another critical area of research need is to understand the molecular structure of the liquid interface and bulk as a function of CO 2 loading, and to assess whether conventional film theories accurately quantify solvent behavior, or if thermodynamic models adequately quantify activity coefficients of ions in solution. We conclude with an assessment of our efforts to aid in bridging the knowledge gaps in understanding water-lean solvents, and suggestions of what is needed to enable large-scale demonstrations to meet the United States Department of Energy’s year 2030 goal.« less
  • Amine solvents are of great interest for post-combustion CO{sub 2} capture applications. Although the development of new solvents is predominantly conducted at the laboratory scale, the ability to assess the performance of newly developed solvents at the process scale is crucial to identifying the best solvents for CO{sub 2} capture. In this work we present a methodology to evaluate and objectively compare the process performance of different solvents. We use Aspen Plus, with the electrolyte-NRTL thermodynamic model for the solvent CO{sub 2} interactions, coupled with a multi-objective genetic algorithm optimization to determine the best process design and operating conditions formore » each solvent. This ensures that the processes utilized for the comparison are those which are best suited for the specific solvent. We evaluate and compare the process performance of monoethanolamine (MEA), diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP) in a 90% CO{sub 2} capture process from a 550 MW coal fired power plant. From our analysis the best process specifications are amine specific and with those specific, optimized specifications DEA has the potential to be a better performing solvent than MEA, with a lower energy penalty and lower capital cost investment.« less
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