High-pressure free radical ethylene polymerization system and ethylene polymerization method

The invention relates to the field of olefin high-pressure polymerization, and discloses a system for high-pressure free radical polymerization of ethylene and an ethylene polymerization method, the system comprises a polymerization unit, a fluid suction conveying unit, an initiator supply unit and a chain transfer agent supply unit; wherein the polymerization unit comprises a first-stage polymerization unit and a multi-stage polymerization unit connected in series at the downstream of the first-stage polymerization unit; the primary polymerization unit comprises at least two tubular reactors which are connected in parallel; the fluid sucking and conveying unit comprises one or at least two fluid sucking and conveying devices which are arranged in parallel and is used for sucking and conveying at least one stream of reaction monomer flow containing an ethylene source and part of materials at a discharge hole of at least one tubular reactor in the primary polymerization unit; the primary polymerization unit at