No abstract

Amine emissions from a post-combustion CO 2 capture process can lead to solvent loss and serious environmental issues. The emission characteristics of amine mixtures and influencing factors are seldom reported. This work comprehensively investigated emissions of AMP (2-amino-2-methyl-1propanol)/MEA (monoethanolamine) from a 3.6 Nm 3 /h flue gas CO 2 capture platform. The condensation nuclei in flue gas dominated the generation of amine aerosols and resulted in a heavy total amine loss of over 1400 mg/Nm 3 , which is equivalent to 5.88 kg/t CO 2 captured under the high nuclei concentration scenario. Inside the absorber, a higher CO 2 concentration and lower lean solvent CO 2 loading can significantly promote the growth of aerosols due to the intensive reaction of CO 2 absorption. The maximum amine emissions were observed at 8−12 vol % CO 2 . The flue gas temperature and liquid/gas ratio had insignificant effects on aerosol emissions, while amine emissions after the absorber increased 340−500% as the lean solvent temperature increased from 30 to 50 °C. A synergistic control strategy of nuclei pretreatment, operating optimization, and water scrubbing can effectively reduce amine emissions to 4.0 mg/Nm 3 MEA and 8.3 mg/ Nm 3 AMP.

CO2 capture using biphasic solvents is a promising technology for a significant reduction in regeneration energy. However, the existing biphasic solvents suffer significant amine loss because volatile tertiary amines with a high concentration (∼60 wt %) are used as the phase separation promoter. To address this drawback, high boiling point physical solvents were employed into aqueous alkanolamines to exploit a biphasic solvent for CO2 capture. We utilized diethylene glycol dimethyl ether (DEGDME) and sulfolane as the phase separation promoters and developed 2-amino-2-methyl-1-propanol (AMP)/monoethanolamine (MEA) blend-based physical–chemical biphasic solvents. Distribution of CO2 loading, amine species, physical solvents, and water in the two phases after CO2 absorption were investigated to optimize the phase separation behavior. 13C NMR analysis indicated that CO2 absorption in an AMP/MEA-based physical–chemical solution is first dominated by CO2 reaction with MEA and then followed by the hydrolysis reaction of AMP carbamate at high CO2 loading. The physical solvents facilitate the extraction of water and CO2 reaction products and result in liquid phase separation. The CO2 absorption rate in AMP/MEA-based physical–chemical solution is faster than in aqueous AMP/MEA. The optimal AMP/MEA-based physical–chemical biphasic solvent shows a 69% higher CO2 capacity and a 36% lower regeneration energy than 30% MEA. Further, both effects of increased viscosity and the phase separation on the regeneration energy were evaluated.

The main research objective of this paper was to optimize the design parameters of the hybrid membrane-absorption CO2 capture process in Natural Gas-steam Cycle (NGCC) power plants. To predict the CO2 concentration in permeate gas and required membrane area, a mass transfer calculation model of CO2/N2/H2O separation membrane was established in Aspen plus. Effect of CO2 recovery rate of membrane unit, operating pressure proportion of feed gas pressure over permeate gas pressure and flue gas flow ratio on membrane area, compressor power and solution regeneration duty were studied based on membrane calculation model. The optimal parameter of feed/permeate side pressure ratio and flow ratio are 10:1 and 50% respectively. The solution regeneration duty of hybrid process reduced at over 20.7% than traditional chemical absorption process.

Using the biphasic solvent for CO2 capture is a novel strategy to reduce the effect of increased viscosity on the regeneration energy.