Pilot Testing of Calcium Looping at TRL7 with CO₂ Capture Efficiencies toward 99%

Postcombustion CO₂ capture by calcium looping using circulating fluidized bed technology, CFB-CaL, is evolving to tackle industrial sectors that are difficult to decarbonize. In addition to the known advantages of CFB-CaL (i.e., retrofittability and competitive energy efficiencies and cost), the fuel flexibility by using renewable biomass in the oxy-fired CFB calciner and the possibility to reach extremely high CO₂ capture efficiencies in the carbonator are demonstrated in this paper. Results from the latest experimental campaigns in the TRL7 CFB-CaL pilot of the La Pereda are reported, treating over 2000 N m³/h of flue gases in the carbonator with a firing capacity of biomass pellets up to 2 MW_th in the oxy-fired calciner. A new strategy to reach high CO₂ capture efficiencies (above 99% in some cases) in the carbonator has been tested. This involves decoupling the carbonator in two temperature zones by cooling the solids-lean top region to below 550 °C and ensuring that a sufficient flow of active CaO reaches such a region.