IMPRESS – Pilot scale demonstration of high pressure stripping in a Mixed Salt based absorption process for CO₂ capture

The major purpose of the IMPRESS project was to develop and demonstrate in a modified configuration at the Tiller pilot in Trondheim a novel, water-lean, mixed-salt-based solvent technology. The project was originally divided into two phases of which the present project (phase 1) has focused on optimization of the solvent system for establishing the basis for a dual-stage process configuration, which enables CO₂ stripping at elevated pressure (high pressure stripping) and at the same time minimizes the emission of solvent and solvent degradation.

The project was based on work with the mixed-salt solvent system (ammonia, potassium carbonate-water system) and associated dual stage process developed by SRI International in Menlo Park, California. The solvent development of this system in the present project implies replacing some of the water with an amine to further enhance the CO₂ absorption rate and reduce the total energy use of an integrated capture plant. The work was done in a joint project with SRI International, in which the two partners focused on different amines in the solvent blend. It turned out that the performance of the two blends was quite similar, but to further improve, SINTEF introduced a blend containing a faster reacting promoter. Preliminary testing of this blend shows promising results, but it should be noted that solvents with NH3 will have significant operational challenges related to emissions, solvent management, and possible precipitation.

The goal of the first phase was not completely reached as the new blend needs further improvement and more testing for validation before the second planned demonstration phase of this project. However, the planned modifications for testing of high-pressure (HP) stripping is presently being implemented at the Tiller pilot in a different project. Since HP-stripping concepts are capable of reducing the compressor duty approximately by 50%, which furthermore implies significant positive effect on the CAPEX and OPEX of the capture plant, solvents targeted for such operation is important for further cost reduction.

More information:
• Project information for DOE project: Mixed-Salt Based Transformational Solvent Technology for CO₂ Capture, https://www.netl.doe.gov/project-information?p=FE0031597
• I. Jayaweera, P. Jayaweera, Y. Yamasaki and R. Elmore, “Mixed-Salt Solutions for CO₂ Capture,” in Absorption-Based Post-combustion Capture of Carbon Dioxide, Elsevier, 2016, pp. 167-200
• Indira Jayaweera, Palitha Jayaweera, Prodip Kundu, Andre Anderko, Kaj Thomsen, Gianluca Valenti, Davide Bonalumi, and Stefano Lillia, (2016), Results from Process Modeling of the Mixed-salt Technology for CO₂ Capture from Post-combustion-related Applications, Presented at GHGT-13 in Lausanne, Switzerland, Nov. 2016, published in Energy Procedia, 114, July 2017, pp. 771-780