Device for recirculating an at least partially gaseous composition containing hydrogen and fuel cell system

A dry rotary pump for recirculation of an at least partially gaseous composition containing hydrogen, the dry rotary pump comprising a first rotating shaft and a second rotating shaft driving respectively a first piston with claws and a second piston with claws in rotation in a pumping chamber comprising an inlet orifice and an outlet orifice for the gaseous composition, the first rotating shaft and the second rotating shaft being configured to be driven in rotation by a drive situated in a gear chamber,

• a first pair of seals and a second pair of seals, each comprising a first shaft seal and a second shaft seal, the first pair of seals being provided around the first rotating shaft and the second pair of seals being provided around the second rotating shaft between the pumping chamber and the gear chamber,
• a pressure equalization chamber in fluid connection with a gap present between the first shaft seal and the second shaft seal of the first and of the second pair of shaft seals to regulate a pressure in the gap,
• the gear chamber being in fluid connection with the gap, and
• the pumping chamber being in fluid connection with the first shaft seal of the first pair of shaft seals and with the first shaft seal of the second pair of shaft seals by a pulsation attenuation chamber.