Denitration treatment system and denitration treatment method for pellet roasting flue gas of chain grate rotary kiln

The invention provides a denitration treatment system and a denitration treatment method for pellet roasting flue gas of a chain grate rotary kiln. The denitration system comprises a chain grate machine, a rotary kiln and an annular cooler, which are connected in sequence; wherein the chain grate machine is used for drying and preheating green pellets and conveying the green pellets into the rotary kiln to be roasted, the rotary kiln is used for roasting the dried and preheated pellets, and the annular cooler is used for cooling the roasted pellets; the rotary kiln is further circularly connected with a chain grate machine through a flue gas return pipeline, and a selective non-catalytic reduction device is arranged on the flue gas return pipeline; and the chain grate is sequentially connected with an ozone generation device and a desulfurization device along the flow direction of the roasting flue gas. According to the invention, staged treatment of NOx is realized, the denitration efficiency of flue gas is