Jorgensen, Thomas | Search NASA

DOE OSTI2022

Efficient carbon capture using sub-textured polymer packing surfaces via 3D printing

Gas absorption is a common unit operation whose performance deeply relies on the gas liquid contact behavior. In this work, we report a solid polymeric surface feature containing microscale striation to improve the solid-liquid and gas-liquid contact and facilitate mass transfer. As a proof of concept, the surface feature is adopted for CO 2 capture absorber packing via 3D printing. Besides traditional embossing texture, an additional laminar striation is applied to the packing surface as a sub-texture. The packing shows notable CO 2 mass transfer increase without interfering with other key operating characteristics including pressure drop and liquid holdup. The improvement is based on the synergy of favorable wettability, thin liquid film and increased liquid mixing from rougher surface. In the demonstration test, the packing height could decrease by 33% using the advanced packing with same CO 2 removal, leading to a significant decrease in equipment size and capital expense for commercial CO 2 capture systems.

3D printing↗

DOE OSTI2022

Oxygen Solubility in Aqueous Amine Solvents with Common Additives Used for CO 2 Chemical Absorption

Major sources of anthropogenic CO 2 are power generation and transportation industries where researcher continue to explore CO 2 emission mitigation strategies as applied to these CO 2 sources through carbon capture, utilization, and sequestration (CCUS). The most mature CO 2 capture technology is post-combustion carbon capture (PCCC) using aqueous amine solutions/solvents, however solvent degradation and regeneration costs are slowing the widespread adoption of PCCC. Solvent degradation of the aqueous amine solutions is mainly caused from the temperature gradient between the absorber and stripper columns and common flue gas components such as SOx, NOx, and oxygen (O 2 ). The two main classifications of solvent degradation are thermal degradation, occurring when the amine reacts with itself at elevated temperatures and anaerobic conditions and oxidative degradation. Oxidative degradation reactions can occur from oxygen mass transfer and free radical oxidation. Metals, such as iron from the corrosion of steel structures used in industrial applications such as PCCC, can help to catalyze these reactions. Various oxidative degradation studies have shown how O 2 concentrations in flue gas and, to a lesser extent, temperature influence the extent of oxidative degradation. Accurately measuring the O 2 solubility, commonly referred to as dissolved oxygen (DO), in a quick, continuous, and efficient manner in aqueous amine solvents should contribute to determine the effectiveness of mitigation strategies for oxidative degradation. Knowing that commercial PCCC amine solvents contain components beyond water, amine, carbonate species and CO 2 , this investigation was conducted to determine the oxygen solubility changes of common aqueous amines solutions with commonly used and published solvent additives. The impact of carbon loadings with and without the additives was also examined. A commercial dissolved oxygen probe was used to measure the DO concentrations and compared them against standard Winkler Method titration values. The results show that antifoam shows minimal change in [DO]. MBT yielded lower DO values, and NaVO 3 showed a higher DO concentration due to interferences. These results indicate that most common amine solvent additives should be expected to minimally impact oxygen solubility and amine oxidative degradation.

60 APPLIED LIFE SCIENCES↗