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Title: Innovative absorber/stripper configurations for CO{sub 2} capture by aqueous monoethanolamine

Abstract

The state-of-the-art technology to capture CO, from coal-fired power plants is absorption/stripping with aqueous monoethanolamine (MEA). The energy consumption in stripping can be 15-30% of the power-plant output. A rigorous rate-based model for CO{sub 2}-MEA-H{sub 2}O qas used to simulate several flowsheet alternatives that reduce the energy requirement using Aspen Plus with RateFrac. Results were calculated for vapor recompression, multipressure, and simple strippers at 5 and 10{sup o}C approach temperatures and 70, 90, and 95% CO{sub 2} removal. The 'equivalent work of steam/mole of CO{sub 2} removed' and the reboiler duty were used to compare the proposed schemes and to show the shift of energy use from work to heat. The total equivalent work for multipressure was less than that for the simple stripper by 0.03-0.12 GJ/(ton of CO{sub 2}), and the reboiler duty was less by 0.15-0.41 GJ/(ton of CO{sub 2}). The multipressure with vapor recompression is an attractive option because it utilizes the overhead water vapor latent heat to reduce reboiler duty load, recovers the work of compression to strip more CO{sub 2}, and shows more reversible behavior.

Authors:
;  [1]
  1. University of Bahrain, Isa Town (Bahrain). Dept. of Chemical Engineering
Publication Date:
OSTI Identifier:
20752215
Resource Type:
Journal Article
Resource Relation:
Journal Name: Industrial and Engineering Chemistry Research; Journal Volume: 45; Journal Issue: 8
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 20 FOSSIL-FUELED POWER PLANTS; CAPTURE; CARBON DIOXIDE; FOSSIL-FUEL POWER PLANTS; COAL; ENERGY CONSUMPTION; COMPUTERIZED SIMULATION; SCRUBBING; WATER VAPOR; COMPRESSION; FLUE GAS

Citation Formats

Jassim, M.S., and Rochelle, G.T. Innovative absorber/stripper configurations for CO{sub 2} capture by aqueous monoethanolamine. United States: N. p., 2006. Web. doi:10.1021/ie050547s.
Jassim, M.S., & Rochelle, G.T. Innovative absorber/stripper configurations for CO{sub 2} capture by aqueous monoethanolamine. United States. doi:10.1021/ie050547s.
Jassim, M.S., and Rochelle, G.T. Wed . "Innovative absorber/stripper configurations for CO{sub 2} capture by aqueous monoethanolamine". United States. doi:10.1021/ie050547s.
@article{osti_20752215,
title = {Innovative absorber/stripper configurations for CO{sub 2} capture by aqueous monoethanolamine},
author = {Jassim, M.S. and Rochelle, G.T.},
abstractNote = {The state-of-the-art technology to capture CO, from coal-fired power plants is absorption/stripping with aqueous monoethanolamine (MEA). The energy consumption in stripping can be 15-30% of the power-plant output. A rigorous rate-based model for CO{sub 2}-MEA-H{sub 2}O qas used to simulate several flowsheet alternatives that reduce the energy requirement using Aspen Plus with RateFrac. Results were calculated for vapor recompression, multipressure, and simple strippers at 5 and 10{sup o}C approach temperatures and 70, 90, and 95% CO{sub 2} removal. The 'equivalent work of steam/mole of CO{sub 2} removed' and the reboiler duty were used to compare the proposed schemes and to show the shift of energy use from work to heat. The total equivalent work for multipressure was less than that for the simple stripper by 0.03-0.12 GJ/(ton of CO{sub 2}), and the reboiler duty was less by 0.15-0.41 GJ/(ton of CO{sub 2}). The multipressure with vapor recompression is an attractive option because it utilizes the overhead water vapor latent heat to reduce reboiler duty load, recovers the work of compression to strip more CO{sub 2}, and shows more reversible behavior.},
doi = {10.1021/ie050547s},
journal = {Industrial and Engineering Chemistry Research},
number = 8,
volume = 45,
place = {United States},
year = {Wed Apr 12 00:00:00 EDT 2006},
month = {Wed Apr 12 00:00:00 EDT 2006}
}
  • Aqueous absorption/stripping is the state-of-the-art technology for the capture of CO{sub 2} from coal-fired power plants. This technology is energy-intensive and has been applied to CO{sub 2} removal from natural gas, ammonia, and hydrogen gas streams. Energy requirements can be reduced by the use of a more-reactive solvent, operating the cross exchanger at a lower temperature, optimizing the stripper operation, and using innovative stripper configurations (vacuum and multipressure). This work calculates stripper performance with an algorithm in Aspen Custom Modeler (ACM) that incorporates thermodynamic studies, reaction rate measurements, physical properties, and contactor-specific information for three stripper configuration-a simple stripper operatingmore » at 160 kPa, a multipressure stripper operating at three pressures (330/230/160 kPa), and a vacuum stripper (30 kPa) for two solvents: 7m (30 wt %) monoethanolamine (MEA) and 5m K{sup +}/2.5m piperazine. The temperature approach is varied from 5 to 10{sup o}C. With some approximations, we predict the influence of using solvents with varying heats of desorption {Delta}H{sub des}) on the reboiler duty and the equivalent work for stripping (reboiler duty as equivalent Carnot work plus compression work). With a rich solution giving PCO{sub 2}{asterisk} = 2.5 kPa at 40{sup o}C, the vacuum stripper is favored for solvents with Delta H{sub des} {<=} 21 kcal/(gmol of CO{sub 2}) while the multipressure configuration is attractive for solvents with {Delta}(H{sub des} {>=} 21 kcal/(gmol of CO{sub 2}).« less
  • Aqueous absorption/stripping is a promising technology for the capture of CO{sub 2} from existing or new coal-fired power plants. Four new stripper configurations (matrix, internal exchange, flashing feed, and multipressure with split feed) have been evaluated with seven model solvents that approximate the thermodynamic and rate properties of 7m (30 wt %) monoethanolamine (MEA), potassium carbonate promoted bypiperazine (PZ), promoted MEA, methyldiethanolamine (MDEA) promoted by PZ, and hindered amines. The results show that solvents with high heats of absorption (MEA, MEA/PZ) favor operation at normal pressure. The relative performance of the alternative configurations is matrix > internal exchange > multipressuremore » with split feed > flashing feed. MEA/PZ and MDEA/PZ are attractive alternatives to 7m MEA. The best solvent and process configuration, matrix with MDEA/PZ, offers 22 and 15% energy savings over the baseline and improved baseline, respectively,with stripping and compression to 10 MPa. The energy requirement for stripping and compression to 10 MPa is about 20% of the power output from a 500 MW power plant with 90% CO{sub 2} removal.« less
  • A dynamic rate-based model was developed for stripping in CO{sub 2} capture from coal-fired power plants with 30 wt% monoethanolamine (MEA). The model, created in a flow sheet of Aspen Custom Modeler, was based on the film theory for liquid and vapor phases. It takes into account the impact of equilibrium reactions on the mass transfer, thermodynamic nonidealities, and the hydraulics of the structured packing. With this model, steady state analyses were. carried out for the stripper to understand the effect of the leah loading and the height of the packing on total equivalent work and find optimum operating conditionsmore » that minimize power plant lost work. Two dynamic strategies with control configurations are proposed to run the stripper in a flexible operation during the period of electricity peak load and prices. Open loop responses demonstrated some differences in dynamic behavior and steady state values for proposed dynamic strategies. One of the approaches increased the CO{sub 2} removal by 1% at the reduced steam rate and provided faster response of the stripper to a step change in the reboiler heat rate.« less
  • Rate-based process modeling technology has matured and is increasingly gaining acceptance over traditional equilibrium-stage modeling approaches. Recently comprehensive pilot plant data for carbon dioxide (CO{sub 2}) capture with aqueous monoethanolamine (MEA) solution have become available from the University of Texas at Austin. The pilot plant data cover key process variables including CO{sub 2} concentration in the gas stream, CO{sub 2} loading in lean MEA solution, liquid to gas ratio, and packing type. In this study, we model the pilot plant operation with Aspen RateSep, a second generation rate-based multistage separation unit operation model in Aspen Plus. After a brief reviewmore » of rate-based modeling, thermodynamic and kinetic models for CO{sub 2} absorption with the MEA solution, and transport property models, we show excellent match of the rate-based model predictions against the comprehensive pilot plant data and we validate the superiority of the rate-based models over the traditional equilibrium-stage models. We further examine the impacts of key rate-based modeling options, i.e., film discretization options and flow model options. The rate-based model provides excellent predictive capability, and it should be very useful for design and scale-up of CO{sub 2} capture processes.« less