Process and apparatus for producing olefin polymers

A process for producing olefin polymers in a loop reactor, wherein at least one olefin monomer is polymerised in slurry phase in a hydrocarbon diluent or liquid monomer, said process comprising

• polymerizing at least one olefin in a loop reactor in slurry phase,
• continuously withdrawing a polymer slurry from the loop reactor,
• increasing the concentration of the polymer slurry by separating it from an overhead stream,
• recycling the overhead stream to the loop reactor,
• recycling a first part of the concentrated slurry back to the loop reactor,
• conducting a second part of the concentrated slurry to a flash unit,
• recovering the polymer from the flash unit,
• compressing a first part of the overhead gas stream in a flash compressor,
• passing the compressed flash gas stream into a heavies column in order to separate oligomers and other heavy components from the gas stream,
• passing a second part of the overhead stream from the heavies column into a flash vessel in order to form a liquid phase and a vapour phase, and
• directing at least a part of the liquid phase into a lights column in order to separate the low-boiling components from the liquid phase.