Abstract: Along with the state’s environmental protection standards becoming increasingly stringent, coal-fired units are required to install denitrification devices to ensure that the flue gas NO_x emission concentration complies with the environmental standards. In this paper, aiming at the frequent scaling and blocking of the air preheater due to the ammonia slipping after the denitrification devices being put into use, the intelligent optimization system is proposed for the SCR denitrafication device to improve the control quality of the denitrafication control system through the budget function of the multi-input and multi-output model, which can reasonably control the ammonia injection volume and reduce the amount of ammonia slip on the premise of meeting the environmental standards. In addition, when slight air preheater fouling blockage occurs, the original online program control soot blowing mode is changed to the manual directed soot blowing mode which focuses on the fouling areas to reduce the risk of blocking the air preheater. The two measures effectively reduce the occurrence of the air preheater blocking problem caused by the operation of the denitrafication device.

Key words: SCR, denitrification control system, intelligent optimization system, NOx, air preheater