Abstract
Capture and storage of carbon dioxide (CO{sub 2}) from power plants is generally considered to be one of the main options for reducing man made atmospheric emissions of CO{sub 2}. One of the most feasible options is the absorption processes used for post combustion CO{sub 2} capture. These technologies are proven at smaller scale for power plant exhaust gases and at large scale for natural gas treating. High CO{sub 2} capture efficiencies can be achieved, but the capital and operating costs are still high. In particular the costs and efficiency drop caused by the energy use of these processes is an obstacle to world-wide use. In the beginning of the 20th century sodium carbonate solutions were used in dry ice plants to separate CO{sub 2} from flue gases. After alkanolamines were introduced the use of sodium carbonate solutions rapidly decreased. This was mainly due to the fact that CO{sub 2} absorption was faster with alkanolamine solutions and that very high CO{sub 2} removal efficiencies could be achieved. However, carbonate systems have been used for special applications for many decades and recently the use of carbonates for post combustion CO{sub 2} removal has gained renewed interest because of the potentially low
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Citation Formats
Knuutila, Hanna.
Carbon dioxide capture with carbonate systems.
Norway: N. p.,
2009.
Web.
Knuutila, Hanna.
Carbon dioxide capture with carbonate systems.
Norway.
Knuutila, Hanna.
2009.
"Carbon dioxide capture with carbonate systems."
Norway.
@misc{etde_1010755,
title = {Carbon dioxide capture with carbonate systems}
author = {Knuutila, Hanna}
abstractNote = {Capture and storage of carbon dioxide (CO{sub 2}) from power plants is generally considered to be one of the main options for reducing man made atmospheric emissions of CO{sub 2}. One of the most feasible options is the absorption processes used for post combustion CO{sub 2} capture. These technologies are proven at smaller scale for power plant exhaust gases and at large scale for natural gas treating. High CO{sub 2} capture efficiencies can be achieved, but the capital and operating costs are still high. In particular the costs and efficiency drop caused by the energy use of these processes is an obstacle to world-wide use. In the beginning of the 20th century sodium carbonate solutions were used in dry ice plants to separate CO{sub 2} from flue gases. After alkanolamines were introduced the use of sodium carbonate solutions rapidly decreased. This was mainly due to the fact that CO{sub 2} absorption was faster with alkanolamine solutions and that very high CO{sub 2} removal efficiencies could be achieved. However, carbonate systems have been used for special applications for many decades and recently the use of carbonates for post combustion CO{sub 2} removal has gained renewed interest because of the potentially low energy requirements of the process This thesis presents experimental, theoretical and modeling work on using the sodium and potassium carbonate for CO{sub 2} capture from power plants: The vapor-liquid equilibria (VLE) of sodium carbonate-CO{sub 2} water system were modeled using the electrolyte NRTL model to predict the activities of the liquid phase. Experimental data were obtained to validate the model. The kinetics of aqueous sodium and potassium carbonate solutions were measured with a string of discs contactor. By using monoethanolamine (MEA) and 3-metylaminopropylamine (MAPA) the effect of amine promotion was studied. Adding amines as promoter gives a tenfold increase in absorption rates compared to pure carbonate solutions. To deduce reaction rate constants from the kinetic data the physical solubility of CO{sub 2} is needed. Therefore, the solubility of N{sub 2}O in aqueous sodium and potassium carbonate with and without MEA and MAPA was measured. In addition, parameters for a N{sub 2}O solubility model available in the literature were refitted to a wider temperature as well as carbonate concentration range. Lab-scale pilot tests with aqueous 10 wt-% sodium carbonate solution confirmed the results of the slow kinetics of unpromoted carbonate systems. Operationally the system behaved well and no problems were encountered. Furthermore, the feasibility of a CO{sub 2} capture system based on a sodium carbonate-bicarbonate slurry was studied by modelling. The theoretically low energy consumption made the system interesting. Nevertheless, due to the slow absorption rate of sodium carbonate the process was found not to be feasible without promoter. Finally, the integration of a CO{sub 2} capture system with power production was studied. Due to high energy efficiency a combined heat and power plant was found to be an attractive option for CO{sub 2} capture. In this power plant it is also possible to divide the energy loss between district heat and electricity according to demand. (Author)}
place = {Norway}
year = {2009}
month = {Jul}
}
title = {Carbon dioxide capture with carbonate systems}
author = {Knuutila, Hanna}
abstractNote = {Capture and storage of carbon dioxide (CO{sub 2}) from power plants is generally considered to be one of the main options for reducing man made atmospheric emissions of CO{sub 2}. One of the most feasible options is the absorption processes used for post combustion CO{sub 2} capture. These technologies are proven at smaller scale for power plant exhaust gases and at large scale for natural gas treating. High CO{sub 2} capture efficiencies can be achieved, but the capital and operating costs are still high. In particular the costs and efficiency drop caused by the energy use of these processes is an obstacle to world-wide use. In the beginning of the 20th century sodium carbonate solutions were used in dry ice plants to separate CO{sub 2} from flue gases. After alkanolamines were introduced the use of sodium carbonate solutions rapidly decreased. This was mainly due to the fact that CO{sub 2} absorption was faster with alkanolamine solutions and that very high CO{sub 2} removal efficiencies could be achieved. However, carbonate systems have been used for special applications for many decades and recently the use of carbonates for post combustion CO{sub 2} removal has gained renewed interest because of the potentially low energy requirements of the process This thesis presents experimental, theoretical and modeling work on using the sodium and potassium carbonate for CO{sub 2} capture from power plants: The vapor-liquid equilibria (VLE) of sodium carbonate-CO{sub 2} water system were modeled using the electrolyte NRTL model to predict the activities of the liquid phase. Experimental data were obtained to validate the model. The kinetics of aqueous sodium and potassium carbonate solutions were measured with a string of discs contactor. By using monoethanolamine (MEA) and 3-metylaminopropylamine (MAPA) the effect of amine promotion was studied. Adding amines as promoter gives a tenfold increase in absorption rates compared to pure carbonate solutions. To deduce reaction rate constants from the kinetic data the physical solubility of CO{sub 2} is needed. Therefore, the solubility of N{sub 2}O in aqueous sodium and potassium carbonate with and without MEA and MAPA was measured. In addition, parameters for a N{sub 2}O solubility model available in the literature were refitted to a wider temperature as well as carbonate concentration range. Lab-scale pilot tests with aqueous 10 wt-% sodium carbonate solution confirmed the results of the slow kinetics of unpromoted carbonate systems. Operationally the system behaved well and no problems were encountered. Furthermore, the feasibility of a CO{sub 2} capture system based on a sodium carbonate-bicarbonate slurry was studied by modelling. The theoretically low energy consumption made the system interesting. Nevertheless, due to the slow absorption rate of sodium carbonate the process was found not to be feasible without promoter. Finally, the integration of a CO{sub 2} capture system with power production was studied. Due to high energy efficiency a combined heat and power plant was found to be an attractive option for CO{sub 2} capture. In this power plant it is also possible to divide the energy loss between district heat and electricity according to demand. (Author)}
place = {Norway}
year = {2009}
month = {Jul}
}