213557 DECAB: A New Process for Post Combustion Capture of CO2

Wednesday, March 16, 2011: 8:05 AM
Buckingham (Hyatt Regency Chicago)
Erin E. Kimball, Earl L.V. Goetheer and Eva Sanchez Fernandez, Separation Technology, TNO, Delft, Netherlands

Contribution AIChE meeting

DECAB: a new process for post combustion capture of CO2

E.L.V. Goetheer, E. Kimball and E. Sanchez Fernandez

This work describes the conceptual design of a novel separation process for CO2 removal from flue gas based on precipitating solvents. The process here described (DECAB) is an enhanced CO2 absorption based on the Le Chatelier's principle, which states that reaction equilibrium can be shifted by removing one of the constituents in the reaction. Depending on the type of amine different species are predominantly formed. In the case of primary amines carbamate is predominantly formed according to the equilibrium reaction (1).

                    (1)

In reaction (1), the equilibrium can be shifted to the formation of carbamate (R-NHCOO-) by removing the protonated amine (R-NH3+) from the reaction medium. This will result in a higher absorption capacity. For this purpose an amino acid species has been selected. Amino acids react with CO2 in principle in the same way as alkanol amines ([5]).

(2)

A conceptual design of this process has been developed based on literature data, thermodynamic principles and a limited number of experiments. The Figure below shows a block diagram that includes the main steps / functions of the process. The flue gas needs to be contacted with the solvent (absorption block). The CO2 reacts with the solvent, as in reaction (2) resulting in a slurry that contains the carbamate and the precipitated amino acid. Crystals are dissolved (crystal dissolution block) and then the solvent is regenerated (Regeneration block) and the resulting CO2 product is compressed.

 Block diagram showing the structure of the process

As solvent example, the potassium salt of taurine was selected. The strategy followed is based on the compilation and determination of the key properties and parameters that govern the absorption and regeneration of the solvent. Then, the performance of the process is evaluated with the aid of short cut design methods. Results show that the key advantages of this process are environmental friendliness (no emissions to the air) and low energy consumption related to a lower vapor pressure of the solvent and higher net loading than conventional processes. The design developed allows for future economic evaluation and assessment of options that will further lead to benefits over conventional processes.


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