High-pressure polymerization process of ethylenically unsaturated monomers in a polymerization reactor

A process for polymerizing ethylene, and optionally one or more comonomers, to obtain an ethylene-based polymer in a high-pressure polymerization system comprising

• a) a continuously operated polymerization reactor having a reactor inlet and having a reactor outlet and
• b) a reactor blow down system comprising a fluid communication system, adapted and arranged to be in fluid communication with the polymerization reactor via the fluid communication system, comprising
• b1) a reactor blow down vessel containing an aqueous quenching medium,
• b2) a first emergency valve arranged in the fluid communication system and adapted to open and close fluid communication between the polymerization reactor and the reactor blow down system,
• b3) a reactor blow down dump vessel arranged and adapted to be in fluid communication with the reactor blow down vessel, and
• b4) a drain valve in the fluid communication system between the reactor blow down vessel and the reactor blow down dump vessel adapted and arranged to open or close fluid communication between the reactor blow down vessel and the reactor blow down dump vessel,
• wherein the reactor blow down vessel is installed above the reactor blow down dump vessel, and
• wherein the process comprises the steps of
• A) monitoring the high-pressure polymerization system for a disturbance, and
• B) opening the first emergency valve, thereby allowing a content of the high-pressure polymerization system comprising polymer and gaseous components to expand into the reactor blow down vessel via the fluid communication system, when a disturbance occurs and wherein the drain valve is closed,
• C) contacting the content of the polymerization system in the reactor blow down vessel with the aqueous quenching medium, thereby obtaining an aqueous polymer slurry,
• D) separating the aqueous polymer slurry and the gaseous components, and
• E) transferring the aqueous polymer slurry to the reactor blow down dump vessel by opening the drain valve.