Technology Centre Mongstad (TCM DA) was established in 2012 to test, verify, and demonstrate different post-combustion capture (PCC) of carbon dioxide technologies. The company is a joint venture between Gassnova (on behalf of the Norwegian state), Equinor, Shell, and TotalEnergies with a common vision for testing and research and development of carbon capture for the deployment of large-scale carbon capture. The facility is located next to the Equinor refinery in Mongstad, Norway and is provided flue gas from a nearby combined cycle gas turbine-based heat-and-power (CHP) plant as well as residue fluid catalytic cracker (RFCC) flue gas from the refinery. The CESAR1 solvent, developed in the EU CESAR project, was utilized for the first time at TCM for the ALIGN CCUS (Accelerating Low Carbon Industrial Growth Through Carbon Capture Utilization and Storage) project test campaign in 2019.
CESAR1 solvent is a blend of 27% wt 2-amino-2-methylpropan-1-ol (AMP) and 13% wt piperazine (PZ). This solvent is considered a better solvent than monoethanolamine (MEA) in terms of thermal energy performance and stability (lower degradation) and has been proposed by the IEAGHG as their new benchmark solvent. TCM DA carried out baseline testing of CESAR1 solvent in June 2020 using flue gas from the CHP source, controlled at 5% CO2 to simulate state of the art gas turbine flue gas, and continued with additional testing that lasted into late 2020 using flue gas from the RFCC source that has higher CO2 concentration.
The main objectives of these campaigns were to produce knowledge and information that can be used to reduce the cost as well as technical, environmental, and financial risks of commercial-scale deployment of PCC using the CESAR1 solvent. This includes the establishment of an RFCC baseline performance with CESAR1 solvent. The Electric Power Research Institute, Inc. assessed the performance of the CESAR1 process using an independent verification protocol (IVP) previously developed for TCM DA during CHP baseline testing MEA solvent. The IVP was also previously updated for use with the RFCC flue gas as this gas contains 13–14% CO2 content whereas the CHP flue gas has ~3.5% CO2 content by volume.
The IVP provides a structured testing procedure for assessing the thermal and environmental performance of PCC processes under normal operating conditions. During the RFCC testing, TCM DA manually collected extractive samples from the depleted gas outlet and the product CO2 outlet throughout the testing period. As part of the IVP, EPRI also assessed plant critical instrumentation at TCM DA for accuracy and precision error based on a comparative analysis during testing operations and against calibration checks. The CESAR1 baseline process was evaluated during twelve individual test periods over three days in November 2020. During the tests, extractive samples were taken to measure process contaminants such as aldehydes, ketones, amines (AMP/PZ), and ammonia.
The extractive sampling and associated analysis techniques applied were consistent with the IVP recommendations. Sulfur oxides and nitrogen oxides were continuously monitored using Fourier transform infrared (FTIR) analyzers on the depleted flue gas and the product CO2 streams. Multiple measurements of the CO2 concentration (FTIR, non-destructive infra-red, and gas chromatography) are available at TCM allowing comparative confirmation of test period stability. The capture rate was calculated via four methods. CO2 recovery (mass balance) was evaluated, and the thermal performance (energy consumption) was assessed based on measured data taken during the tests.
The CO2 capture rate achieved during the testing was about 91%, providing specific reboiler duties (SRD) of 3.2–3.3 GJ/t-CO2 and the CO2 gas mass balance closures were close to 100%. These data and assessments, along with the results from TCM DA sampling during these tests, will be presented in this paper and provide a baseline case for CESAR1 solvent in higher concentration flue gas capture cases.