Device for extracting a chemical compound from an acid gas, of which the initial composition, the flow rate and the partial pressure of the chemical elements that form it are known, this device comprising a shell that defines a volume passed through by the gas and that is equipped at a first end with an inlet through which the contaminated gas rushes in and at a second end with an outlet through which the decontaminated gas escapes, the device comprising at least one decontamination stage in the shell, this decontamination stage comprising means for injecting an acid solution into the gas, characterized in that the decontamination stage comprises: - a condensate recovery plate positioned upstream of the injection means relative to the direction of movement of the gas, this recovery plate being sized so that the recovery plate seals the shell of the device, the recovery plate being permeable to gases and impermeable to liquids; - a recovery circuit comprising a recovery tank in fluidic connection, on the one hand, with the recovery plate for receiving the condensates and in fluidic connection, on the other hand, with the injection means in order to supply these means with acid solution using a fluidic pump; - means for measuring the temperature of the gases at the inlet of the decontamination stage and means for measuring the temperature of the acid solution; - a control unit in which a program is executed, this program being configured in order to carry out steps: ∘ of measuring the temperature of the gases at the inlet of the decontamination stage; ∘ of measuring the temperature of the acid solution to be sprayed; ∘ of adjusting the temperature of the acid solution so that the gases are cooled to a temperature just below the dew point or the azeotrope point of the chemical compound to be condensed; ∘ of spraying the acid solution into the decontamination stage; ∘ of recovering the chemical compound condensed in the form of liquid phase condensates; ∘ of injecting the solution recovered into the shell of the decontamination stage. - a condensate recovery plate positioned upstream of the injection means relative to the direction of movement of the gas, this recovery plate being sized so that the recovery plate seals the shell of the device, the recovery plate being permeable to gases and impermeable to liquids; - a recovery circuit comprising a recovery tank in fluidic connection, on the one hand, with the recovery plate for receiving the condensates and in fluidic connection, on the other hand, with the injection means in order to supply these means with acid solution using a fluidic pump; - means for measuring the temperature of the gases at the inlet of the decontamination stage and means for measuring the temperature of the acid solution; - a control unit in which a program is executed, this program being configured in order to carry out steps: ∘ of measuring the temperature of the gases at the inlet of the decontamination stage; ∘ of measuring the temperature of the acid solution to be sprayed; ∘ of adjusting the temperature of the acid solution so that the gases are cooled to a temperature just below the dew point or the azeotrope point of the chemical compound to be condensed; ∘ of spraying the acid solution into the decontamination stage; ∘ of recovering the chemical compound condensed in the form of liquid phase condensates; ∘ of injecting the solution recovered into the shell of the decontamination stage. ∘ of measuring the temperature of the gases at the inlet of the decontamination stage; ∘ of measuring the temperature of the acid solution to be sprayed; ∘ of adjusting the temperature of the acid solution so that the gases are cooled to a temperature just below the dew point or the azeotrope point of the chemical compound to be condensed; ∘ of spraying the acid solution into the decontamination stage; ∘ of recovering the chemical compound condensed in the form of liquid phase condensates; ∘ of injecting the solution recovered into the shell of the decontamination stage.