A gasifier 10 includes a first
chemical process loop 12 having an exothermic oxidizer reactor 14 and an endothermic
reducer reactor 16. CaS is oxidized in air in the oxidizer reactor 14 to form hot CaSO4 which is discharged to the
reducer reactor 16. Hot CaSO4 and carbonaceous fuel received in the
reducer reactor 16 undergo an endothermic reaction utilizing the heat content of the CaSO4, the carbonaceous fuel stripping the
oxygen from the CaSO4 to form CaS and a CO rich
syngas. The CaS is discharged to the oxidizer reactor 14 and the
syngas is discharged to a second
chemical process loop 52. The second
chemical process loop 52 has a water-gas shift reactor 54 and a calciner 42. The CO of the
syngas reacts with gaseous H2O in the shift reactor 54 to produce H2 and CO2. The CO2 is captured by CaO to form hot CaCO3 in an
exothermic reaction. The hot CaCO3 is discharged to the calciner 42, the heat content of the CaCO3 being used to strip the CO2 from the CaO in an endothermic reaction in the calciner, with the CaO being discharged from the calciner 42 to the shift reactor 54.