Pilot testing of a non-aqueous solvent (NAS) CO2 capture process

Abstract

RTI International and SINTEF with funding from the US Department of Energy and Gassnova have been working on advancing
RTI’s non-aqueous solvent (NAS) technology for CO2 capture from flue gases. The process technology has the potential to
substantially reduce the regenerator heat duty to less than 2.0 MJ/kg-CO2 captured, a 30% to 50% reduction compared to state-of
the-art post-combustion CO2 capture processes using aqueous amine solvents. RTI and SINTEF have carried out pilot-scale
testing of NAS at SINTEF’s Tiller CO2 capture test facility using coal burner derived flue gas. This publication focuses on the
NAS performance based on test results from SINTEF pilot test facilities.
The substantial reduction in the regeneration energy is the result of reducing the contribution from the heat of absorption (ΔHabs),
essentially eliminating the heat of vaporization contribution due to the low water content and high boiling point of the NASs at
the regeneration temperatures and reducing the sensible heat contribution by lowering the specific heat capacity and increasing
the working capacity (Δα) under process conditions.
The NAS CO2 Capture Process has been tested and benchmarked with monoethanolamine (MEA) based on a conventional CO2
capture process at SINTEF’s Tiller plant. The team has determined the optimal conditions and configurations to run the NAS at
bench scale to realize the reduction in regenerator heat duty. A few, yet significant modifications, have been made to the
conventional aqueous amine pilot test facility at Tiller to obtain optimal performance of the NAS. Several key aspects of the NAS
CO2 Capture Process have been extensively evaluated during pilot testing with emphasis on understanding the operation of the
NAS process and the effect that water from the flue gas has on the NAS CO2 capture process, specifically in terms of system
operability, CO2 capture efficiency, water balance, and energy consumption.
In this publication, we will focus on discussing test results from the pilot test. We will show why and how the existing process
equipment at Tiller was modified with NAS-specific process equipment, and ultimately establish process feasibility and prove
substantially lower solvent regeneration energy of the NAS CO2 capture process. The overarching objective of the current
development phase is to finalize the process design aspects that are specific to the NAS CO2 capture process, reduce the uncertainty and risks related to the process and economic variables, and ready the NAS process for large scale testing and demonstration.