Patent ID: 6951908

Claim:
A process for preparing polyethylene in tube reactors and/or in combination with autoclaves, in which a free-radical initiator is introduced into a flowing medium comprising ethylene and possibly comonomers and which comprises at least the following steps: generation of rotation by mixing two streams to be mixed ( 61 , 62 ) at an angle ( 66 ) or generation of rotation in a stream ( 61 ) by means of a swirl element ( 20 ), provision of a cross-sectional constriction ( 63 , 67 ; 71 ) with an inlet zone upstream of the feed point ( 72 , 81 ) for a free-radical initiator into a reaction tube ( 1 ), introduction of the free-radical initiator through an off-center outlet orifice ( 44 ) into the flowing, rotating medium ( 61 , 62 ; 70 ) and provision in a downstream direction of a mixing zone and a cross-sectional widening with an outlet.