A closed-loop nitrogen transport system including a first transfer line configured for nitrogen pressure conveyance of a polymer fluff from at least one upstream vessel to at least one downstream vessel, a second transfer line configured to return a nitrogen gas stream comprising primarily nitrogen from the at least one downstream vessel to the at least one upstream vessel, a conveyor blower operable to provide flow throughout the closed loop, and a treatment unit operable to remove hydrocarbons from at least a portion of the nitrogen gas stream comprising primarily nitrogen, to provide a purified nitrogen stream.