A commercial pathway for evaluating the performance of a novel amine solvent blend in a mini-pilot plant for carbon capture

Abstract

This study investigates the performance of a novel solvent bi-blend, 4M (2:2) AMP:1-(2HE) PRLD, for CO2 capture through absorption and desorption, providing a potential alternative to the conventional 5M Monoethanolamine (MEA). The pathway utilized to assess the performance of the amine bi-blend for commercial application involved conducting carbon capture experiments in a laboratory bench-scale mini-pilot plant. This approach aimed to validate the solvent's performance under conditions that mimic a full-scale commercial industrial CO2 capture plant. The research also addresses the urgent need for more efficient and cost-effective carbon capture solutions to combat increasing greenhouse gas emissions and global warming. Experiments were conducted with varying feed gas compositions, with CO2 concentrations ranging from 4.5% to 30%, to simulate different industrial emission scenarios. Key performance metrics, including CO2 absorption efficiency, cyclic capacity, mass transfer rates, and energy consumption for solvent regeneration, were meticulously evaluated. For a CO2 partial pressure of 4.5%, the novel solvent blend demonstrated significant performance enhancements compared to 5M MEA. Specifically, the 4M (2:2) AMP:1-(2HE) PRLD blend exhibited an enhancement in absorption efficiency by up to 25% at a reboiler temperature of 110 °C, 41% at 100 °C, and over 700% at 90 °C. Additionally, there was a reduction in regeneration energy requirements by approximately 30% at 110 °C, 43% at 100 °C, and 84% at 90 °C. The novel blend showed robust performance across a wide range of these parameters, indicating its versatility and suitability for diverse industrial applications. The study also revealed an average increase of 150% in the overall gas phase volumetric mass transfer coefficient (KGav) and 110% for the overall liquid-phase volumetric mass transfer coefficient (KLav). These significant improvements emphasize the novel blend's superior mass transfer performance, which is crucial for maximizing CO2 capture efficiency and column design. Parametric studies were conducted to understand the influence of various operational parameters on mass transfer performance. It was observed that the absorption efficiency and mass transfer rates were significantly influenced by CO2 loading, gas flow rate, desorption temperature and pressure. Results from this exercise showed that there is a strong positive correlation between the reboiler temperature and the efficiency as well as the overall mass transfer coefficient. It was also noted that the mass transfer was mainly controlled by the liquid phase while increasing the desorber pressure had an inverse effect on the lean amine loading which was attributed to the higher gas solubility at the higher pressure. The effect of CO2 partial pressure was also studied and a negative correlation was observed between CO2 partial pressure and the absorber efficiency, overall gas phase mass transfer coefficient. Heat duty analysis revealed that the novel solvent blend required less energy for regeneration, thus offering a more energy-efficient solution. The specific energy consumption for the AMP-PRLD blend was found to be significantly lower than that for 5M MEA, highlighting its potential to reduce operational costs and environmental impacts. The study concludes that the novel solvent blend not only provides a more efficient CO2 capture solution but also aligns with the goals of reducing greenhouse gas emissions and achieving net-zero emissions from the indirect co-combustion of natural gas and biomass for energy generation even at relatively lower desorption temperature (100-110 °C) thus significantly contributing to energy savings.