Method and apparatus for separating carbon dioxide from a residual gas in a fluidised bed catalytic cracking plant (FCC)

A process for separating carbon dioxide from a waste gas of a fluid catalytic cracking installation containing carbon dioxide, nitrogen and carbon monoxide, the process comprising:

• i) converting at least a portion of the carbon monoxide of the waste gas into carbon dioxide to form a flow enriched in carbon dioxide by combustion,
• ii) separating at least a portion of the flow enriched in carbon dioxide from step i) by adsorption to form a gas enriched in carbon dioxide and depleted in nitrogen and a gas rich in nitrogen and depleted in carbon dioxide, and at least a portion of the gas enriched in carbon dioxide and depleted in nitrogen is separated in a separation apparatus at a temperature of less than 0° C. by partial condensation and/or by distillation to form a fluid rich in carbon dioxide and a fluid depleted in carbon dioxide and
• iii) sending a gas containing at least 90% oxygen and a gas containing at least 40% carbon dioxide, consisting either of a product of the separation of the flow enriched in carbon dioxide, or of a portion of the flow enriched in carbon dioxide, to the combustion of step i).