Method for controlling nitrogen content in Al deoxidization steel by converter process

The invention belongs to the technical field of ferrous metallurgy, in particular relates to a method for controlling nitrogen content of aluminum killed steel produced in a converter process, and is used for preventing the problem that the nitrogen content increases in the aluminum killed steel produced in the converter process. The technical problem is solved by controlling the nitrogen content of the aluminum killed steel produced in the converter process according to the technical proposal as follows: the alkalinity of converter slag CaO/SiO2 is adjusted to 5-7 when a converter starts to produce the slag, the denitrification rate can be increased in the converter smelting process by controlling the alkalinity of the converter slag, the denitrification rate is increased from 50%-70% to 65%-85%, and the terminal nitrogen content of the molten steel in the converter can be controlled within 15PPm. The alkalinity is controlled, special slag is added, and a seal washer with brim is employed to seal between a steel ladle lower opening and a protection tube before starting continuous casting, thus realizing the stable control that the casting blank nitrogen content is not more than 35PPm by an LD-LF-SCC process and the casting blank nitrogen content is not more than 30PPm by an LD-LF-RH-BCC process.