Modified grate furnace waste incineration device

The invention discloses a modified grate furnace waste incineration device. An air vent is formed in the rear arch of a hearth of a waste incineration furnace, is connected with the air chamber of a fire grate at the drying section of an incinerator through a pipeline, and is also connected with an outlet flue of the hearth of the incinerator through the pipeline; the coal economizer outlet of a waste heat boiler joins the pipeline connected with the air vent of the rear arch of the hearth through the pipeline; a circulating fan is further arranged on the pipeline; an air conditioning bypass is arranged at the inlet of the circulating fan. According to the invention, partial hot smoke containing certain content of oxygen at the tail part of the hearth and the partial hot smoke at the outlet of the coal economizer are recycled, so that drying and preheating of waste and disturbance and combustion support of smoke are met, the fed combustion air amount and the total smoke amount can be effectively reduced, the oxygen content of a combustion area is reasonably controlled, improvement of the waste combustion quality is facilitated, improvement of the utilization efficiency of combustion thermal energy is also facilitated, and the content of pollutants in the discharged flue gas is decreased.