High CO2 Absorption Capacity Research Articles

Performance of MEA and amine-blends in the CSIRO PCC pilot plant at Loy Yang Power in Australia

Chemical reactive liquid absorption in post-combustion carbon capture (PCC) has sparked an interest of many researchers for improvement in creating high CO2 absorption capacity and minimising the reboiler heat duty for regeneration.This paper discusses results from performance trials on different solvents: mono-ethanolamine (MEA-baseline), a mixture of MEA with 2-amino-2-methyl-1-propanol/AMP (Blended Amine 1) and Blended Amine 2 (a propietary solvent developed by Research Institute of Innovative Technology for the Earth (RITE), Japan). The trials were carried out in CSIRO’s PCC pilot plant at Loy Yang Power. The pilot plant receives flue gas from this 2.2GW brown coal-fired power station in the Latrobe Valley, Victoria. The study has shown the benefits of using blended solvents for CO2 capture in terms of CO2 recovery and reboiler duty for solvent regeneration.The correlation of CO2 recovery and process parameters, i.e., liquid and gas (L/G) ratio and lean loading, has been established for the range of solvents tested. The results show that, in general, an increase of L/G ratio increases the CO2 recovery. It is also noted that a solvent at higher lean loading requires a greater solvent (recycle) flow rate, or vice versa, in order to capture a given amount of CO2. The effect of reducing the stripper’s bottom temperature from 115 to 112°C reduced the CO2 recovery of both MEA and Blended Amine 1 as their solvent lean loadings are raised. The same temperature change, however, did not significantly decrease CO2 recovery of Blended Amine 2, as it also shown by insignificant changes in solvent lean loadings.The results also indicate that the reboiler heat duty is dependent upon L/G ratio, solvent lean loading and blending solvent type. For the MEA-115°C, a minimum reboiler heat-duty as a function of L/G ratio is clearly observed and the Blended Amine 1–112°C has also shown a similar pattern. In contrast, Blended Amine 1–115°C showed excessive energy duty, which indicates unfavourable condition for this solvent. This is not the case for Blended Amine 2. It is observed that the reboiler heat duty decreases as stripper bottom temperature decreases, which in turn raises the lean loading for both MEA and Blended Amine 1. On the other hand, the lean loading of Blended Amine 2 in the temperature range examined did not affect the reboiler heat duty changes. The investigation also found that the magnitude of reboiler duty is decreasing following the order MEA>Blended Amine 1>Blended Amine 2.In order to obtain CO2 recovery of 85%, the Blended Amine 2–115°C (L/G=3.60) has similar reboiler duty relative to that of MEA-115°C with L/G ratio of 4.12. For the Blended Amine 1 (L/G=3.04), however, the reboiler heat duty increased by 51% at a similar temperature. The temperature reduction to 112°C decreased the reboiler heat duty of both Blended Amines 1 and 2 by 11% (L/G=4.01) and 14% (L/G=3.60) respectively. Further raising the CO2 recovery to 90–95%, in comparison to that of MEA at 115°C with L/G ratio of 4.20, the reboiler heat duty of Blended Amine 1 has risen by 49% (L/G=3.95) and of Blended Amine 2 dropped by 5% (L/G=3.52) under a similar temperature. At 112°C, the reboiler heat duty of Blended Amine 1 decreased by 18% (L/G=5.02). Blended Amine 2 may give a similar reboiler heat duty if run at a larger L/G ratio.Overall, the result of the MEA baseline and blending solvents has shown different behaviours of CO2 stripping. The distribution of the components of reboiler heat duty may explain this difference. For MEA, the condenser heat, which equals the heat needed for water evaporation, is a major contributor to the reboiler duty. For both Blended Amine solvents, the magnitude of sensible heat and the heat of CO2 desorption are more pronounced than the condenser heat. At the minimum reboiler duty reached by MEA and Blended Amine 1, the condenser heat share is lower than the other reboiler duty components. Therefore, further works involve optimisation of the PCC process with blended Amines and other blends.

Efficient Theoretical Screening of Solid Sorbents for CO<sub>2</sub> Capture Applications

By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO2 sorbent candidates from the vast array of possible solid materials has been proposed and validated. The ab initio thermodynamic technique has the advantage of allowing identification of thermodynamic properties of CO2 capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. For a given solid, the first step is to attempt to extract thermodynamic properties from thermodynamic databases and the available literatures. If the thermodynamic properties of the compound of interest are unknown, an ab initio thermodynamic approach is used to calculate them. These properties expressed conveniently as chemical potentials and heat of reactions, which obtained either from databases or from calculations, are further used for computing the thermodynamic reaction equilibrium properties of the CO2 absorption/desorption cycles. Only those solid materials for which lower capture energy costs are predicted at the desired process conditions are selected as CO2 sorbent candidates and are further considered for ex- perimental validations. Solid sorbents containing alkali and alkaline earth metals have been reported in several previous studies to be good candidates for CO2 sorbent applications due to their high CO2 absorption capacity at moderate work- ing temperatures. In addition to introducing our computational screening procedure, in this presentation we will sum- marize our results for solid systems composed by alkali and alkaline earth metal oxides, hydroxides, and carbonates/bicarbonates to validate our methodology. Additionally, applications of our computational method to mixed solid systems of Li2O with SiO2/ZrO2 with different mixing ratios, our preliminary results showed that increasing the Li2O/SiO2 ratio in lithium silicates increases their corresponding turnover temperatures for CO2 capture reactions. Overall these theoretical predictions are found to be in good agreement with available experimental findings.

Thermo Physical Analysis of 2-amino-2-methyl-1-propanol Solvent for Carbon Dioxide Removal

Removal of acid gases such as carbon dioxide (CO2) is normally carried out by aqueous solutions of alkanolamines. The traditional amines used for acid gas removal include; mono-ethanolamine (MEA), di-ethanolamine (DEA) and N-methyldiethanolamine (MDEA). There is a need to investigate new solvents to minimize the carbon emissions since the traditional amines have low CO2 loading capacity and require high energy for regeneration. Recently, a new class of amines, sterically hindered amines is identified as one of the potential solvent for acid gas removal due to their relatively higher CO2 absorption capacity, low heat of regeneration and higher values of rate constant. One of the identified solvent that has potential for commercialization is sterically hindered amine known as 2-amino-2-methyl-1-propoanol (AMP). The investigation of thermophysical properties of this solvent is essential in the design and optimization for smooth operation of acid gas removal process. The density, viscosity, surface tension and refractive index are the most important physical properties for this purpose which is presented in this paper. These properties of aqueous solutions of 2-amino-2-methyl-1propanol (AMP) are investigated over the industrially important temperature range of 298.15 K to 333.15 K. The thermal analysis of aqueous solutions was also carried out using TGA (Thermal gravity analyzer) with the heating rate of 10 °C·min under nitrogen (N2) environment in order to investigate the thermal stability of the solvent. All the investigated properties are correlated as a function of temperature for ease of usage in the design of acid gas removal system. The correlated and measured data are in good agreement.

Density, Viscosity, Heat Capacity, Surface Tension, and Solubility of CO2 in Aqueous Solutions of Potassium Serinate

The density, viscosity, and heat capacity of aqueous potassium serinate solutions were measured over the temperature range from (298.15 to 353.15) K in the mass fraction range of (7.2 to 57.3) %. Each physical property was correlated with temperature and mass fraction, by regression analysis, and the corresponding coefficients for each property are presented here. The surface tension of the aqueous potassium serinate solution was also measured over the mass fraction range of (7.2 to 57.3) % at 298.15 K. In addition, the solubility of carbon dioxide in a 14.3 mass % aqueous potassium serinate solution was measured at (313.15, 343.15, and 373.15) K over partial pressures of CO2 ranging from (0.1 to 400) kPa. It was shown that the aqueous potassium serinate solution could be a good CO2 absorbent because of its high cyclic CO2 absorption capacity. Furthermore, it might be suitable for membrane gas absorption due to its higher surface tension.

New synthesis method for CaO-based synthetic sorbents with enhanced properties for high-temperature CO2 -capture

In this paper, a new synthesis method to obtain mixed CaO/Ca12Al14O33 solids for high temperature CO2 capture is presented. The modification of a pure phase Ca3Al2O6 solid through a thermal treatment under controlled conditions leads to a high CO2 absorption capacity material, with very promising long term stability during absorption/desorption cycles. The influence of the calcination temperature during the synthesis of the Ca3Al2O6 powders, and the temperature and atmosphere applied during the thermal treatment was studied. Therefore, optimum conditions for high stabilization rate and high final CO2 absorption capacity of the sorbent could be determined. Comparison with a natural sorbent (dolomite) over 150 carbonation/calcination cycles is also included, showing a substantial improvement of the synthetic solid CO2-uptake at long term use, compared to that of natural sorbents.

CO<sub>2</sub>の高圧分離回収プロセスを用いたCCSの経済性向上

Tens of million tons per year of CO2 are being captured from raw feed gas by natural gas plants and are then being released to the atmosphere. As interest in reducing CO2 emissions from the natural gas plants has increased in recent years, CO2 capture and storage (CCS) has gained in importance. Among the several types of CO2 capture technologies, chemical solvent based technology is widely used to meet product natural gas specification in CO2 contentThis paper discusses a new chemical solvent based CO2 capture technology (HiPACT ; High Pressure Acid-gas Capture Technology), a new concept to improve economic efficiency in CCS implementation, jointly developed by JGC and BASF. The solvent has high stability against thermal degradation, which enables high pressure and elevated temperature operation during solvent regeneration to reduce CO2 compression cost downstream. The solvent also has a higher CO2 absorption capacity than commercially available solvent technologies, which results in decreased solvent circulation rates and lower AGRU (Acid Gas Removal Unit) capital and operating costs. After the concept has been confirmed with pilot plant runs with stimulant gas, a demonstration test using INPEX's commercial natural gas plant has successfully completed.

Synthesis of Zeolite A from By-Product of Aluminum Etching Process: Effects of Reaction Temperature and Reaction Time on Pore Volume

Problem statement: Increasing of the carbon dioxide (CO2) concentration in the atmosphere creates a global warming. Zeolite is used as CO2 absorbent. Approach: By-products from aluminum etching process, which carry a large amount of Al2O3 content, are useable as raw materials for synthesis zeolites type A using hydrogel process. A pore volume of zeolites is the key to achieve high CO2 absorption capacity. In this study, two-factor factorial experiments with 3 replicates and α = 0.05 have been conducted to examine the influence of reaction temperature and reaction time on the pore volume and to determine the process conditions for containing the highest pore volume. Three levels of the reaction temperature of 75, 85 and 95°C and three levels of the reaction time of 1, 2 and 3 h (s), while the stirring speed is controlled at 300 rpm, are selected for the experiment. The mole ratios of the starting reactants are fixed at 2 of SiO2/Al2O3, 2 of Na2O/ Al2O3 and 85 of H2O/Na2O. Analysis of surface area is performed by the BJH method and the DR method for analysis of gas adsorption- desorption using nitrogen. Results: The results found that there was significant interaction between the reaction temperature and the reaction time and at 95°C of 3 hours gave the highest pore volume, resulting in 0.0205cc g −1 of the BJH method and 0.0065 cc g −1 in the DR method. Besides, the CO2 absorption test is also performed with the zeolite synthesized at 95°C. Conclusion: Zeolite syntheses of by product from alkaline etching of the aluminum industry have a major analysis agree well with those of reference zeolite A. Adsorption test with CO2, yield the best result with ZA31, with the capacity of 0.1023 ccg -1 .

Synthesis and Characterization of CaO Nanopods for High Temperature CO2 Capture

A hollow structured CaO sorbent with high CO2 absorption capacity and good cyclic performance at high temperatures was derived from the corresponding CaCO3 precursor, which was prepared by bubbling...

Modified Polyamines for CO2 Absorption. Product Preparation and Characterization

Aliphatic polyamines easily absorb acidic gases but unfortunately are not suitable for industrial application because their solutions are difficult to regenerate. Molecular modification is of primary importance to reduce their basicity and to allow their use in acid gas recovery processes. Various modified polyamines were prepared by reacting tetraethylenepentamine (TEPA) with formaldehyde and formaldehyde/phenol in various molar ratios. The physical and chemical characterization of the synthesized products showed a general reduction of basicity; the modification of TEPA with formaldehyde and phenol gave products with high CO2 absorption capacity and easier regeneration; moreover, the heat of reaction during CO2 absorption was reduced. The selected compound had a TEPA/CH2O/C6H5OH ratio equal to 1/0.5/0.4. This new product showed higher cyclic capacity, higher absorption rate, and lower degradation compared with diethanolamine under the same experimental conditions. The product is stable, constant in compo...