The invention discloses a chemical chain hydrogenation device and a chemical chain hydrogenation method based on iron-based
oxygen carrier graded reduction. The device is a circulation loop composed of an air reactor, a
cyclone separator, a reduction reactor, a fuel reactor, a return feeder, a steam reactor, and an
isolator. According to the method, a Fe3O4-state iron-based
oxygen carrier is oxidized into a Fe2O3-state iron-based
oxygen carrier with air in the air reactor; separation is carried out in the
cyclone separator; the Fe2O3-state iron-based oxygen carrier enters the reduction reactor, and is reduced into Fe3O4-state iron-based oxygen carrier with weakly reductive gas; the Fe3O4-state iron-based oxygen carrier enters the fuel reactor through a
discharge pipe of the reduction reactor, and is reduced to FeO-state iron-based oxygen carrier with a gaseous fuel; the FeO-state iron-based oxygen carrier enters the steam reactor through the return feeder, and is subjected to a reaction with steam, such that the FeO-state iron-based oxygen carrier is converted into a Fe3O4-state iron-based oxygen carrier, and at a same time
hydrogen is produced and is discharged through a
hydrogen discharge pipe of the steam reactor; the Fe3O4-state iron-based oxygen carrier enters the air reactor through the
isolator, and is subjected to an oxidation reaction with air, such that the regeneration of the Fe2O3-state iron-based oxygen carrier is completed.