Study on C02 Absorption in Single MEA and Mixed MEA & DEA

Theoverall effect of greenhouse warming caused by increasing amount of carbon dioxide
(CO2) in the atmosphere has lead to growing interest in research for new methods to
reduce the C02 emissions. One such alternative is to recover C02 from flue gas by
chemical absorption with alkanolamines, which can be then used for CO2 sequestration.
Alkanolamines have long been used for removing CO2 and hydrogen sulfide (H2S) from
natural gas streams. The classes of alkanolamines are divided into primary amines
(monoethanolamine, MEA), secondary amines (diethanolamine, DEA) and tertiary
amines (monodiethanolamine, MDEA). The objectives of this study are to study the
effect of solvent flow rate and amine concentration in effective CO2 removal as well as to
recommend optimum percentage of mixed primary and secondary amines for efficient
C02 absorption. The use of mixture of primary and secondary amines would maximize
the individual properties of the single amines. The experiment was conducted in a wetted
wall gas absorption column with variousMEA concentrations, varying solvent flow rate
and varying mixtures of amines. From the experiment, the effect of increasing solvent
flow rate would lead to overall better CO2 removal. For solvent concentration, an
increase of amine concentration would increase the maximum overall CO2 removal
efficiency. The optimum blend of amines from this study is reported as DEA-25wt% and
MEA-10.2wt% based on the maximum total moles of C02 effectively removed with this
blend. From this study, the main factor which drives the C02 absorption process in a
mixed amine system is the concentration of MEA in the mixture. A decrease in MEA
concentration would lead to a decrease in the total moles of CO2 removed.