Complete catalyst roasting or regenerating method

An industrial furnace (1) for roasting or regenerating spent petroleum catalysts containing sulfur and carbon, comprising:

• an inlet for catalysts in the form of a plurality of spent solids, called spent catalysts, and an outlet for the catalysts in the form of a plurality of roasted or regenerated solids, called roasted or regenerated catalysts, after desulfurization via exothermal reaction in the presence of oxygen;
• a device for setting the catalysts in motion along the bottom of the furnace to cause the catalysts to circulate from the inlet towards the outlet (40) of the furnace;
• a first zone in the vicinity of the inlet of the furnace decarbonizing the spent catalysts to obtain decarbonized catalysts, followed by:
• a second zone located between the first zone and the outlet of the furnace, said second zone comprising a plurality of oxygen feed devices distributed along the length of the second zone and placing the decarbonized catalysts in contact with the feed oxygen;
• said second zone also comprising one or more variators of the oxygen feed flow rate as a function of the temperature of the catalysts moving in the second zone, said second zone desulfurizing the decarbonized catalysts to obtain roasted or regenerated catalysts;
• and
• a device to evacuate the roasted or regenerated catalysts on leaving the furnace.