Liquid amine–solid carbamic acid phase-separation system for direct capture of CO2 from air

The phase separation between a liquid amine and the solid carbamic acid exhibited >99% CO2 removal efficiency under a large-scale gas stream of 400 ppm CO2. Isophorone diamine [IPDA; 3-(aminomethyl)-3,5,5-trimethylcyclohexylamine] reacted with CO2 in the CO2/IPDA molar ratio of ≥ 1 even in H2O as a solvent. The captured CO2 was completely desorbed at 333 K because the disolved carbamate ion releases CO2 at low temperature. The reusability of IPDA under CO2 adsorption-and-desorption cycles without degradation, the >95% efficinecy kept for 100 hours under direct air capture condition, and high CO2 capture rate (214 mmol/h for 1 mol amine) suggest that the phase separation system using IPDA is robust and durable for practical use.

Investigation on the Removal of Carbon Dioxide Exhausted from Industrial Units in a Lab-Scale Fluidized Bed Reactor

In this study, CO2 removal efficiency from flue gas was investigated in a fluidized bed reactor under semi-dry conditions. A lab-scale fluidized bed reactor, filled with inert glass beads, was used to investigate the effect of operating parameters on the CO2 removal efficiency using calcium hydroxide slurry as the absorbent. The Taguchi design method was used to design the experiments. The maximum inlet concentration of CO2 was 3 vol%. The most important factors were the reaction surface area, inlet gas velocity, inlet CO2 concentration, absorbent solution flow rate, inlet gas temperature and calcium hydroxide slurry concentration. The experimental results indicated that the CO2 removal efficiency increased when increasing the effective surface area of the reaction. Moreover, the removal efficiency increased by decreasing the input gas flow rate and inlet CO2 concentration. By performing experiments under optimum conditions, the maximum obtained CO2 removal efficiency was 79%. Copyright © 2020 BCREC Group. All rights reserved

Mass Transfer Performance Study for CO2 Absorption into Non-Precipitated Potassium Carbonate Promoted with Glycine Using Packed Absorption Column

The removal of carbon dioxide (CO2) at offshore operation requires an absorption system with an environmentally friendly solvent that can operate at elevated pressure. Potassium carbonate promoted with glycine, PCGLY, is a green solvent that has potential for offshore applications. For high solvent concentrations at elevated pressure, the by-product of CO2 absorption consists of precipitates that increase operational difficulty. Therefore, this study was done to assess the CO2 absorption performance of non-precipitated PCGLY with concentration 15wt%PC+3wt%GLY, which is known to have comparable solubility performance with MDEA. A packed absorption column was used to identify the CO2 removal efficiency, mass transfer coefficient in liquid film, k l a e , and overall volumetric mass transfer coefficient, K G a v . A simplified rate-based model was used to determine k l a e and K G a v based on the experimental data with a maximum MAE value, 0.057. The results showed that liquid flow rates and liquid temperature gives significant effects on the k l a e and K G a v profile, whereas gas flow rate and operating pressure had little effect. The CO2 removal efficiency of PCGLY was found to be 77%, which was only 2% lower than 1.2 kmol/m3 MDEA. K G a v of PCGLY is comparable with MDEA. The absorption process using PCGLY shows potential in the CO2 sweetening process at offshore.

Modelling and simulation study of CO2 capturing process in coal fired power plant using various amine solvents

In the present world, Scientists are very much concern on to reduce the concentration level of carbon dioxide in environment to save the world. In the present work, the CO2 capturing efficiencies of three different amine solvents were analyzed. The selected solvents were mono-ethanol amine (MEA), solvent containing mixture of methyl diethanol amine (MDEA) and piperazine (PZ) called activated -MDEA and aqueous ammonia (NH3) solution. Rigorous simulation method was considered in the current study. The effects of different key parameters for different solvents on the CO2 removal efficiency were analyzed. Packing height, solvent temperature and absorber height were the significant influential parameters for MEA system whereas for activated-MDEA (a-MDEA), those are the ratio of the solvent to feed quantity and the mixed solvent PZ concentration level. For aqueous NH3 solution, absorber and stripper’s temperature, CO2 loading, concentration of NH3, height of the absorber, lean and rich solvent flow rate, boil up ratio, regeneration energy, temperature of the condenser, and duty of the reboiler were considered. The comparative study showed that MEA process recovered the maximum CO2 from flue gas. But it was suffered by the maximum regeneration duty. a-MDEA with PZ recovered 91% CO2. Overall, technically, a-MDEA was the best choice as solvent. Compared to a-MDEA and MEA, aqueous ammonia was identified as more propitious and environment friendly solvent due to its satisfactory performance and easy availability.

CO2 Capture of the Gas Emission, Using a Catalytic Converter and Airlift Bioreactors with the Microalga Scenedesmus dimorphus

A process composed by a catalytic converter and three sequential Airlift photobioreactors containing the microalga Scenedesmus dimorphus was studied to capture CO2, NOx, and CO from emissions of a steam boiler which was burning diesel. The catalytic converter transformed to CO2 a maximum of 78% of the CO present in the combustion gas. The effects of shear rate, light intensity, and light/dark cycles on the biomass growth of the algae were studied. It was observed that at low shear rates (Re ≈ 3200), a high productivity of 0.29 gcel L−1 d−1 was obtained. When the microalga was exposed to 60.75 µmol·m−2·s−1 of intensity of light and a light/dark cycle of 16/8 h, a maximum productivity of 0.44 gcel L−1 d−1 and a maximum CO2 fixation rate 0.8 g CO2 L−1·d−1 were obtained. The maximum CO2 removal efficiency was 64.3%, and KLa for CO2 and O2 were 1.2 h−1 and 3.71 h−1 respectively.

CO2 REMOVAL EFFICIENCY FROM NATURAL GAS AT ELEVATED PRESSURE OF PACKED ABSORPTION COLUMN USING POTASSIUM CARBONATE PROMOTED WITH GLYCINE

This article reports the absorption removal efficiency for carbon dioxide (CO2) capture from natural gas using an environmental friendly solvent, potassium carbonate promoted with glycine. Recently, CO2 capture using this solvent (with precipitating) was studied by previous researchers. However, the precipitates of the solvent increase the potential of blockage in the packing and piping thus result failure in absorption processes. Therefore, this study focused to assess the CO2 removal efficiency of non-precipitating potassium carbonate promoted with glycine. This green solvent contains aqueous blend of 20 wt% potassium carbonate and 8 wt% glycine. The absorption performance of the solvent was obtained by demonstrated a few experimental works using a bench scale packed absorption column. The packing type was Sulzer metal gauze and the column consisted of six sampling point which located equidistance along the packing The system was running over a range of liquid flow rate 1.81-7.22 m3/m2.h at fixed operating pressure (4 Mpa), CO2 inlet concentration (20%), gas flow rate (33 kmol/m2.h) and solvent temperature (60 . The effect of liquid flow rate was assessed in term of its CO2 removal efficiency and concentration profile along the packing. The study shows the increasing trend of CO2 removal as liquid flow rate increases. Higher liquid/molar flow rate gas (L/G) offers a better absorption performance compared to lower L/G ratio. This study demonstrated the efficient absorption up to 77 % using non-precipitating potassium carbonate promoted with glycine.

Biotechnology Carbon Capture and Storage (CCS) by Mix-culture Green Microalgae to Enhancing Carbon Uptake Rate and Carbon Dioxide Removal Efficiency with Variation Aeration Rates in Closed System Photobioreactor

Carbon dioxide (CO2) sequestration by green microalgae is receiving increased attention in alleviating the impact of increasing CO2 in the atmosphere. The goal of this study was to explore the capacity of mixed culture green microalgae Chlorella sp, Scenedesmus obliquus, and Ankistrodesmus sp. as carbon capture and storage agent to enhance CO2 uptake rate and CO2 removal efficiency which was observed at elevated CO2 aeration rates of 2, 5, and 8 L min-1 supplied to vertical photobioreactor continuously in batch system culture. The operation condition of this research were 6.5-7.5 pH, temperature of 300C, light intensity of 4000 lux with 16 hours light period and 8 hours dark period, and high pure CO2 elevated level of 5 to 18 (concentration in %; v/v in the aeration gas) as inorganic carbon. The maximum CO2 removal efficiency of the mix culture was 59.80% when the biomass was obtained at 4.90 gL-1 and CO2 flow rate (Lmin-1) of 5 vvm in a vertical photobioreactor. The value of CO2 removal efficiency improved by almost 200% and 120% as compared to that in the low and high aeration rate (2 Lmin-1 and 8 Lmin-1) respectively. The CO2 up take rate of a mixed culture reach 979.62 mg carbon L-1day-1, which was enhancing by 3-fold in high aeration rate (8 Lmin-1). The results showed that the CO2 removal efficiency and carbon uptake rate was related to biomass concentration and aeration rate of CO2 supplied.