Prediction and validation of external cooling loop cryogenic carbon capture (CCC-ECL) for full-scale coal-fired power plant retrofit

Bench-scale experiments and Aspen Plus™ simulations document full-scale, steady-state performance of the external cooling loop cryogenic carbon capture (CCC-ECL) process for a 550 MWe coal-fired power plant. The baseline CCC-ECL process achieves 90% CO2 capture, and has the potential to capture 99+ % of CO2, SO2, PM, NO2, Hg, and most other noxious species. The CCC-ECL process cools power plant flue gas to 175 K, at which point solid CO2 particles desublimate as the flue gas further cools to 154 K. Desublimating flue gas cools in a staged column in direct contact with a cryogenic liquid and produces a CO2-lean flue gas that warms against the incoming flue gas before venting. The CO2/contacting liquid slurry separates through a filter to produce a CO2 stream that warms to 233 K and partially flashes to provide a CO2-rich product. The CO2-rich product (99.2%) liquefies under pressure to form a product for enhanced oil recovery (EOR) or sequestration. All contacting liquid streams cool and cycle back to the staged column. An internal CF4 refrigeration cycle transfers heat from melting CO2 to desublimating CO2 by cooling contact liquid. An external cooling loop of natural gas or other refrigerant provides the additional heat duty to operate the cryogenic process. The nominal parasitic power loss of operating CCC-ECL is 82.6 MWe or about 15% of the coal-fired power plant's rated capacity. In different units, the energy penalty of CCC-ECL is 0.74 MJe/kg CO2 captured and the resulting net power output is decreased to 467 MWe. Lab- and skid-scale measurements validate the basic operation of the process along with the thermodynamics of CO2 solids formation.