A method of using oxygen or peroxide as initiator to polymerize ethylene into low density polyethylene. Ethylene enters the reactor after two-stage compression, where it is polymerized into polyethylene under pressure of 100-300 MPa, temperature of 200-300°C and the action of initiator. The reactants are separated under reduced pressure, so that unreacted ethylene is recycled and melted. After adding plastic additives, the polyethylene is extruded and pelletized.
There are two types of polymerization reactors: tubular reactor (tube length up to 2000 m) and tank reactor. The single-pass conversion rate of the tubular process is 20% to 34%, and the single-line annual production capacity is 100 kt. The single-pass conversion rate of the kettle process is 20%-25%, and the single-line annual production capacity is 180 kt.