A device for circulating a gas in a closed circuit, has an upstream end and a downstream connected to the circuit, the device including: a first chamber defining a first internal volume and having an at least partially conical shape having a minimum diameter situated at a level of the upstream end; a second chamber defining a second internal volume and positioned downstream of the first chamber and having an at least partially conical shape having a minimum diameter situated at a level of the downstream end; an impeller including blades arranged regularly around an axis of rotation, the impeller positioned between the first and second chambers; and a rotation device to rotate the impellers. The first internal volume is larger than the second internal volume. The conical shape of the first chamber has an angle (αA) smaller than the angle (αB) of the conical shape of the second chamber.