Method for improving a polymerization reaction by taking out and analysing a sample

A method for preparing polyethylene comprising:

• providing a first slurry loop polymerization reactor and a second slurry loop polymerization reactor, wherein the first and second slurry loop polymerization reactors are fluidically connected;
• providing a sampling device, wherein the sampling device comprises:
• a sample conduit connected to the first slurry loop polymerization reactor for receiving a sample of polymer particles in a liquid diluent from the first slurry loop polymerization reactor;
• a sample release valve disposed in the sample conduit;
• an automatic flushing mechanism in fluid connection with the sample conduit;
• a flash tank fluidically connected to the sample conduit comprising an inlet connected through a flash line to the outlet of the sample release valve, a first outlet for the removal of polymer particles from the flash tank and a second outlet for the release of gas from the flash tank;
• a sample receiving chamber having an inlet for receiving the sample of polymer particles and an analyzer;
• and
• a sample transfer line extending from the flash tank to the sample receiving chamber and provided with at least one valve with the outlet of the at least one valve connected to the sample receiving chamber;
• removing a sample from the first slurry loop polymerization reactor;
• analyzing the sample from the first slurry loop polymerization reactor;
• based on the results of the analysis of the sample, determining the reaction conditions inside the first slurry loop polymerization reactor;
• and
• based on the reaction conditions inside the first slurry loop polymerization reactor, adjusting the reaction conditions in the first slurry loop polymerization reactor.