A device for injecting a powdered compound for the abatement of pollutants of flue gases into a furnace pipe, said device comprising: - a chamber connected to a peripheral pipe and arranged to be connected on the one hand to a first blowing element arranged to blow a peripheral gas into said chamber and into said peripheral pipe and on the other hand to said furnace pipe via said peripheral pipe, - said peripheral pipe comprising a first portion having a diameter DP1, connected to the chamber, and a second portion having a diameter DP2, opposite the first portion, having a downstream end, and intended to be in communication with the furnace pipe, - a powdered compound conveying pipe intended to be connected to a second blowing element arranged to blow a conveying gas into said conveying pipe, simultaneously to the peripheral gas jet, said conveying pipe having a diameter DT and a downstream end, said first portion of the peripheral pipe being passed through by said conveying pipe concentrically and longitudinally, in such a way that the downstream end of said conveying pipe is located in a secant plane between the first and the second part of the peripheral pipe, the diameter of the conveying pipe and the diameter of the second part of the peripheral pipe being related by the following relationship: 0 < DP2 - DT < 1⁄2 DT, characterised in that said conveying pipe passes through the chamber impermeably and exits concentrically to the peripheral pipe inside said peripheral pipe, and in that the second portion of the peripheral pipe has a length L greater than or equal to the diameter of the second portion of the peripheral pipe. - a chamber connected to a peripheral pipe and arranged to be connected on the one hand to a first blowing element arranged to blow a peripheral gas into said chamber and into said peripheral pipe and on the other hand to said furnace pipe via said peripheral pipe, - said peripheral pipe comprising a first portion having a diameter DP1, connected to the chamber, and a second portion having a diameter DP2, opposite the first portion, having a downstream end, and intended to be in communication with the furnace pipe, - a powdered compound conveying pipe intended to be connected to a second blowing element arranged to blow a conveying gas into said conveying pipe, simultaneously to the peripheral gas jet, said conveying pipe having a diameter DT and a downstream end, said first portion of the peripheral pipe being passed through by said conveying pipe concentrically and longitudinally, in such a way that the downstream end of said conveying pipe is located in a secant plane between the first and the second part of the peripheral pipe, the diameter of the conveying pipe and the diameter of the second part of the peripheral pipe being related by the following relationship: 0 < DP2 - DT < 1⁄2 DT, characterised in that said conveying pipe passes through the chamber impermeably and exits concentrically to the peripheral pipe inside said peripheral pipe, and in that the second portion of the peripheral pipe has a length L greater than or equal to the diameter of the second portion of the peripheral pipe. said first portion of the peripheral pipe being passed through by said conveying pipe concentrically and longitudinally, in such a way that the downstream end of said conveying pipe is located in a secant plane between the first and the second part of the peripheral pipe, the diameter of the conveying pipe and the diameter of the second part of the peripheral pipe being related by the following relationship: 0 < DP2 - DT < 1⁄2 DT, characterised in that said conveying pipe passes through the chamber impermeably and exits concentrically to the peripheral pipe inside said peripheral pipe, and in that the second portion of the peripheral pipe has a length L greater than or equal to the diameter of the second portion of the peripheral pipe. 0 < DP2 - DT < 1⁄2 DT, characterised in that said conveying pipe passes through the chamber impermeably and exits concentrically to the peripheral pipe inside said peripheral pipe, and in that the second portion of the peripheral pipe has a length L greater than or equal to the diameter of the second portion of the peripheral pipe.