Outcomes from pilot plant trials of precipitating potassium carbonate solvent absorption for CO2 capture from a brown coal fired power station in Australia

A precipitating potassium carbonate (K2CO3) based solvent absorption process has been developed for capturing carbon dioxide (CO2) from industrial sources. Demonstration of this process has been completed using real flue gas in a pilot plant located at Hazelwood power station in Victoria, Australia. The pilot plant was designed to capture up to 1 tonne per day of CO2 and was operated over a number of campaigns to test the absorption performance of a liquid solvent (30 wt% K2CO3), a precipitating solvent (45 wt% K2CO3) and a promoted precipitating solvent (promoter with 45 wt% K2CO3). The main aim of this study was to collect operational data from the industry based pilot plant absorber in order to validate thermodynamic experiments and further improve simulation models developed from lab-scale precipitating column trials using synthetic feed gas. The performance of the industry based absorber including CO2 capture rate, pressure drop, solvent loadings and temperature profile, has been measured over a range of operating conditions. The CO2 capture rate improved when operating with a lower gas flow rate, higher solvent temperature and when a rate promoter was added to the solvent. The highly concentrated solvent trials created some difficulties with absorber flooding and intermittent operation due to blockages at start-up but minimal issues were encountered once the system was stabilized. Process simulations have been developed to successfully predict the pilot plant performance over a range of operating conditions. Completion of these pilot plant trials has provided confidence in plant operation and will enable an improved full-scale design and costing of this slurry based solvent process to be completed for commercial scale.