Low-parameter boiler with multiple flue gas recirculation rates

The invention discloses a low-parameter boiler with multiple flue gas recirculation rate, which is characterized in that a boiler preceding-stage heating surface, an economizer, an air preheater and an induced draft fan are sequentially arranged on a flue behind a combustor and a combustion chamber, a flue between the combustion chamber and the boiler preceding-stage heating surface is provided with a flue gas recirculation inlet, and a flue in front of the economizer is provided with a flue gas adjusting baffle plate; a flue between the boiler preceding-stage heating surface and the flue gas adjusting baffle is provided with a flue gas recirculation outlet; the flue gas recirculation inlet and the flue gas recirculation outlet are connected through a bypass pipeline, and a flue gas recirculation fan is arranged on the bypass pipeline; when the boiler is started, the flue is closed by the flue gas adjusting baffle, the flue gas recirculation fan is started, and when the flue gas recirculation ratio reaches a