Ultra-low emission denitration device for ERDIII cement plant

The utility model discloses an ultra-low emission denitration device for an ERDIII cement plant. The ultralow-emission denitration device for the ERDIII cement plant comprises a decomposing furnace and a powder denitration agent conveying device, a secondary air inlet is formed in the bottom of the decomposing furnace; the secondary air inlet is connected with a rotary cement kiln; the decomposition furnace comprises a reduction zone, a main combustion zone, a re-combustion zone and a burnout zone from bottom to top. Wherein the reduction zone is provided with a reduction zone saturated steamcatalytic combustor, the re-combustion zone is provided with a re-combustion zone saturated steam catalytic combustor, the main combustion zone is connected with tertiary air, the after-combustion zone is connected with over-fire air, a discharge pipe of the powder denitration agent conveying device is connected with a denitration agent spray gun, and the denitration agent spray gun is connected with the re-combustion zon