FIELD: chemical industry. SUBSTANCE: device for production of ethylene polymer has pipelines including tied vertically installed pipes in which, at least, one of vertical tied pipes has coaxial outer pipe tied with it. Outer pipe forms heat-exchange jacket, means for introduction of reagent for polymerization and cold carrier, means for discharge of reaction products and cold carrier, and means for producing flow in pipelines. Vertically installed pipes are connected to form closed circuit, and, at least, one vertical pipe has outer surface made of rolled sheet whose two edges are connected to form seam. Method for production of ethylene polymer includes introduction into reaction pipeline of, at least, one monomer, catalyst and diluent to form polymerization reaction mixture passing through pipeline. Polymerization process is effected in closed circuit of pipeline. In this case, at least, one monomer includes, mainly, ethylene, or at least, one monomer contains ethylene and the other monomer contains olefin whose weight amounts to less than 25%. EFFECT: higher efficiency. 9 cl, 3 dwg
