Ethylene polymerization processes and reactor systems for the production of multimodal polymers using combinations of a loop reactor and a fluidized bed reactor

A polymerization reactor system for producing a multimodal ethylene polymer, the system comprising:

• (a) a first loop reactor configured to contact a catalyst composition with ethylene, an optional first olefin comonomer, and optional hydrogen in an inert hydrocarbon diluent under slurry or supercritical polymerization conditions to produce a first ethylene polymer,
• wherein the first loop reactor is further configured to maintain a Dean number of from 3,000,000 to 15,000,000 for a reaction mixture flowing through two or more elbow sections in the first loop reactor;
• (b) a second loop reactor configured to contact a first reactor effluent containing the first ethylene polymer with ethylene, an optional second olefin comonomer, and optional hydrogen under slurry or supercritical polymerization conditions to produce a second ethylene polymer;
• (c) a transfer line configured to withdraw the first reactor effluent containing the first ethylene polymer from the first loop reactor and to introduce the first reactor effluent into the second loop reactor;
• (d) a second discharge line configured to withdraw a second reactor effluent containing the second ethylene polymer from the second loop reactor;
• (e) a separator configured to remove a light fraction comprising hydrogen from the second reactor effluent to form an intermediate material containing the second ethylene polymer, wherein hydrogen is present in the first loop reactor, the second loop reactor, or both;
• and
• (f) a fluidized bed reactor configured to contact the intermediate material containing the second ethylene polymer with ethylene and an optional third olefin comonomer in an inert gas and/or hydrocarbon under gas phase polymerization conditions to produce the multimodal ethylene polymer;
• wherein the transfer line is configured to withdraw the first reactor effluent from the first loop reactor at a discharge location downstream of a first loop reactor circulating pump and to introduce the first reactor effluent into the second loop reactor at a feed location upstream of a second loop reactor circulation pump.