System and method for synchronously recovering nitrogen and carbon dioxide from boiler flue gas

A system for synchronously recovering nitrogen and carbon dioxide from boiler flue gas, characterized in that, the system comprises:

• a flue gas pretreatment system used for dehydrating and cooling a boiler flue gas;
• a carbon and nitrogen separation system communicated with the flue gas pretreatment system, and used for performing pressure swing adsorption on a pretreated flue gas and separating a nitrogen-containing vent gas and a crude carbon dioxide gas, an adsorption pressure of the carbon and nitrogen separation system being 0.20-0.40 MPa;
• a carbon dioxide secondary purification system communicated with the carbon and nitrogen separation system, and used for performing secondary purification on the crude carbon dioxide gas separated from the carbon and nitrogen separation system;
• and
• a nitrogen concentration and purification system communicated with the carbon and nitrogen separation system and the carbon dioxide secondary purification system, and used for purifying the nitrogen-containing vent gas separated from the carbon and nitrogen separation system and a vent gas generated by the carbon dioxide secondary purification system.