(572c) Evaluation of Consumption Energy in CO2 Absorption Processes with Two-Liquid Phase Separation Type

The global issue of climate change is receiving ever-increasing attention. One of the main focuses of this attention is the reduction of CO₂ emission from activities such as power generation, iron and steels making process. The technology that has the potential to make a significant impact on emission is CO2 capture and storage.

The aqueous of amine CO2 capture proses can remove CO2 from exhaust gas in some industrial process. The major aqueous amine absorbent which is applied in industrial process are primary amines, the secondary amines and the tertiary amines. The aqueous of amine CO2 capture proses are consumed thermal energy for CO2 desorption. A previous study has revealed that a lot of energy for CO2 desorption are CO2 desorption heat, sensible heat of the aqueous for desorption temperature and the heat of vaporization the aqueous.

We suggest new CO₂ absorption processes with two-liquid phase separation type for reducing consumption energy. Absorbing liquid in new process consist of H2O, amines and ether or alcohol additive. In CO2 absorption section, the CO2 react to amine in absorber column. The CO2-rich solution liquid is transferred to the decanter. In the decanter, the CO2-rich solution liquid was separated hydrophilic liquid and hydrophobic liquid. Carbamate and bicarbonate ion exist in hydrophilic liquid. Hydrophobic liquid is only additive. The hydrophilic liquid is transferred to the stripper where comparatively high temperature is used to desorb the CO2. The hydrophobic liquid is transferred to mixer. It is mixed with hydrophobic liquid returned to stripper. The new CO₂ absorption processes can be reduced energy consumption for sensible heat of the aqueous for desorption temperature and the heat of vaporization the aqueous. In this work, we select 2-(Ethyl amino) ethanol, water and diethylene glycol diethyl ether to Absorbing liquid. We examine the CO2 absorption characteristics. We study the effect of the new Absorbing liquid on energy consumption for process. We determine the comparison of absorbing liquid. (H2O, EAE, diethylene glycol diethyl ether = 10, 30, 60 wt%) We measure the solubility of CO2 on this absorbing liquid. In experiment, we obtained amount of CO2 are measured to be 0.3 (mol-CO2/mol-amine) at absorber temperature 40 degree C. The new absorbing liquid has the enough loading amount of CO2. We find out that the enough performance is obtained as absorbing solution.

Consumption energy of the new process is calculated by process simulator. The consumption energy is calculated to be 2.5 (GJ/t-CO2). This value is lower than that obtained for MEA absorption process. Thus, CO₂ absorption processes with two-liquid phase separation type can be valuable in CO2 capture and separation technology.