Pilot plant demonstration of a Non-Aqueous Solvent CO₂ Capture Process for Coal-Fired Power Plants (NAS-Pilot)

The projects main objective was to demonstrate and further develop a concept using non-aqueous solvent at SINTEFs pilot plant at Tiller, Trondheim. Non-aqueous solvents (NAS) represent a relatively new concept within post-combustion CO₂ capture.

These solvents have different physical and chemical properties compared to conventional amine-based solvents and may have a potential for significant energy savings. The main research partner in the project was Research Triangle Institute (RTI, USA), who has worked with NAS solvents for some time.

Before the project started SINTEF and RTI cooperated in the CLIMIT demo project, NASCHAR, where the main focus was degradation of various NAS solvents.

In the present project the focus was on pilot testing. Totally five campaigns have been conducted. The first one was on a smaller lab pilot where the differences to water-based solvents were checked-out and a lot of practical experience with these systems was gained. Afterwards two campaigns were performed on the Tiller pilot plant, one with NAS and one with MEA for comparison.

The results showed a significant reduction in energy consumption with NAS. The results were further used for planning and implementing plant modifications such that the plant become more optimal for running NAS. Intercooling between each section in the absorber, inter-heating between each section in the desorber, an additional water wash section and increased crossover heat exchanger area were installed.

After completing the plant modification two additional campaigns were done. The solvent was tested for close to 1600 hours in these two campaigns.

The measurements showed an energy consumption as low as 2.46 MJ/kg CO₂. This corresponds to an energy consumption of 2.29 MJ/kg CO₂ if one takes the estimated heat loss of 1.5 kW into consideration.

The campaigns also showed that the technology presently has some challenges that must be solved, e.g. high amine emissions in the flue gas from the absorber.