Coal Chemical-Looping Combustion for Electricity Generation: Investigation for a 250 MWe Power Plant

Chemical-looping combustion (CLC) is generally based on interconnected fluidized beds where a solid oxygen carrier provides the oxygen for combustion in a fuel reactor (FR). The reduced oxygen carrier is then regenerated to oxidized state in an air reactor (AR) before being recycled to FR to complete the loop. CLC may be suitable and highly promising for power plants with near-zero CO2 emissions. This paper presents, from process thermodynamic modelling, a theoretical investigation of coal chemical-looping combustion for electricity generation with usual steam cycle. The technical issue of unburned compounds minimization at FR outlet is examined through direct oxygen injection in FR. Heat recovery systems are combined on the one hand with a supercritical seam cycle suited to low corrosivity of depleted air from AR, and on the other hand with a sub-critical steam cycle used in open-loop for steam production to fluidize oxygen carrier in FR and gasify char obtained from coal pyrolysis. The integrated configuration presented at one design point is shown to be promising in terms of net plant efficiency (41.6%LHV) including CO2 capture and compression.