Automatic control system for boiler flue gas waste heat recovery

The utility model discloses a boiler flue gas waste heat recovery automatic control system which comprises a first boiler, a second boiler, a first heat exchanger, a second heat exchanger, a heat preservation water tank, a first circulating pump, a second circulating pump, a third circulating pump and a PLC. The top of the second heat exchanger is connected to the bottom of the first heat exchanger through a smoke connecting pipe, the second boiler is connected to the smoke connecting pipe through a first smoke pipe, the first heat exchanger is connected with one end of an electromagnetic valve through a first hot water pipe, and the other end of the electromagnetic valve is connected with the top of the heat preservation water tank through a third hot water pipe. A first water return pipe is led out of the bottom of the heat preservation water tank and connected to one end of a first circulating pump, one end of a second circulating pump and one end of a third circulating pump respectively, and the other end