NOX CONTROL METHOD FOR COAL FIRED BOILER

摘要

PURPOSE:To decrease a variation of NOx at the outlet portion of a boiler by detecting NOx within the exhaust gas at the outlet of the boiler, and by controlling a flow of the air for fuel to the over air port on the basis of the detected NOx value. CONSTITUTION:NOx meter to detect a NOx value within the exhaust gas 7 is established at the outlet portion, leading the detected NOx value 17 of NOx meter 16 to a subtractor 18, seeking for the difference thereof by comparing it with NOx setting 19, and adjusting an OAP flow control damper 14 of the over air port through the PI controller on the basis of the differential signal 20. Therefore, the OAP flow control damper 14 can be automatically controlled to decrease a variation of NOx volume at the outlet of the boiler 5, and also stabilization of control of denitrification plant on the downstream can be attained.