Gas processing equipment and gas processing method, and carbon dioxide capture system and carbon dioxide capture method

A gas processing method and equipment, the equipment includes an oxygen remover 2 that removes oxygen contained in exhaust gas such as combustion gas, and a gas processing device 3 such as an absorber, that processes pretreated exhaust gas from which the oxygen has been removed by the oxygen remover 2 with a treatment agent such as carbon dioxide absorbent solvent. Also disclosed is a carbon dioxide capture method and system, the system comprises an oxygen remover, an absorber that separates carbon dioxide from pretreated exhaust gas, a regenerator that diffuses the carbon dioxide from the carbon dioxide absorbent solvent discharged from the absorber, and a regenerator discharged gas containing the carbon dioxide. The gas processing method and equipment provide suppression of oxygen mixtures to a treatment agent such as an absorbent solvent thereby maintaining performance of the treatment agent.