Process for Improving the Polymerization of Ethylene and One or More Optional Comonomer(s) in a Polymerization Loop Reactor

A double loop reactor comprising:

• a first loop reactor and a second loop reactor in series having a flow path for a polymer slurry, wherein the polymer slurry comprises monomer, one or more optional co-monomers, a polymerization catalyst, liquid diluent and solid ethylene polymer particles;
• multiple means for feeding hydrogen into the double loop reactor, which are positioned spatially separated along a path of the double loop reactor;
• a pump suitable for maintaining the polymer slurry in circulation in said reactor;
• one or more controllers adapted to control a hydrogen:monomer along the flow path by feeding hydrogen into the multiple means for feed hydrogen and reducing the variation in the hydrogen:monomer ratio between the ratio at the double loop reactor inlet and at the double loop reactor outlet to a variation that is lower than 40%;
• one or more settling legs connected to the pipes of the double loop reactor for settling of polymer slurry;
• and
• one or more lines for discharging settled polymer slurry out of the double loop reactor.