Flue gas waste heat utilization system based on boiler system

The invention belongs to the technical field of boilers, and particularly relates to a flue gas waste heat utilization system based on a boiler system. According to the technical scheme, the flue gas waste heat utilization system based on the boiler system comprises a boiler body, the tail of the boiler is connected with an inlet flue, the inlet flue is connected with an air preheater, the other end of the air preheater is connected with an outlet flue, and the flue gas waste heat utilization system further comprises a primary air flue and a secondary air flue; the primary air duct and the secondary air duct pass through the air preheater, the primary air duct is connected to the coal mill, the outlet end of the coal mill is connected with the boiler body through a pipeline, and the secondary air duct is connected to the boiler body; a bypass heating system is connected between the inlet flue and the outlet flue, and the bypass heating system is connected to a pipeline between the coal mill and the boiler bod