Abstract: A method for the analysis by on-line gas phase chromatography of a gaseous phase produced by an olefin polymerization process which includes carrying out a chromatographic analysis of a gaseous phase produced by an olefin polymerization process with carrier gases containing mainly hydrogen and/or nitrogen, wherein the content of oxygen and of water of the hydrogen and the nitrogen in the carrier gases is less than 5 ppm by weight.

Abstract: A process for controlling a continuous fluidised bed reactor (co-)polymerisation process which comprises (1) withdrawing from the reactor a hot recycle stream containing a principal monomer and at least one other unreacted reactant, (2) cooling part or all of the recycle stream withdrawn from the reactor, and (3) recycling part or all of the cooled recycle stream containing the principal monomer and the unreacted reactant(s) through the polymerisation zone in the reactor in the presence of a polymerisation catalyst under reactive conditions, wherein the controlling process consists in maintaining at least one of the reactant gradients (Gri) within a range of values outside which sheeting or unstable operations would otherwise occur.

Abstract: The present invention relates to a process for controlling a continuous fluidized bed reactor (co-)polymerisation process which comprises (1) withdrawing from the reactor a hot recycle stream comprising a principal monomer and at least one other unreacted reactant, (2) cooling part or all of said recycle stream withdrawn from said reactor, and (3) recycling part or all of said cooled recycle stream comprising the principal monomer and the unreacted reactant(s) through the polymerisation zone in said reactor in the presence of a polymerisation catalyst under reactive conditions, characterised in that the said controlling process consists in maintaining at least one of the reactant gradients (Gri) within a range of values outside which sheeting or unstable operations would otherwise occur.