Abstract: The invention relates to a device for taking out and analysing a sample from a polymerisation reactor comprising one or more sample conduits (2), for taking a sample out of said reactor and for conducting said sample to one or more sample flash tanks (3), whereby said conduits each are in communication with said reactor (19) and each are provided with at least two sampling valves (4, 5); comprising one or more sample flash tanks (3), for separating said solid particles and evaporated gas, whereby said sample flash tanks are connected to said conduits (2) and provided with means for analysing said evaporated gas (7), and comprising one or more sample receivers (6), for purifying said solid particles, whereby said receivers are connected to said sample flash tanks (3) and provided with means (8) for analysing said solid particles. The invention further relates to a method for improving a polymerisation reaction in a polymerisation reactor.

Abstract: The present invention provides a multiple loop reactor suitable for polymerizing olefins comprising at least two interconnected loop reactors, whereby said connection essentially consists of one or more transfer lines suitable for transferring polymer slurry from a reactor to another reactor and whereby said transfer line extends substantially horizontally. The invention further relates to a process for producing olefin polymers in a multiple loop react or according to the invention. The invention also relates to the use of a transfer line for transferring polymer slurry from a reactor to another reactor in a multiple loop reactor comprising at least two interconnected loop reactors, whereby said transfer line extends substantially horizontally.

Abstract: The present invention relates to an apparatus and process for polymerizing olefins. One embodiment comprises polymerizing at least one monomer in a first loop reactor in the presence of a catalyst to produce a first polyolefin fraction. A portion of the first polyolefin fraction is transferred to a second loop reactor, connected in series with the first loop reactor. The process further comprises polymerizing in the second loop reactor at least one monomer in the presence of a catalyst to produce a second polyolefin fraction in addition to the first polyolefin fraction. The combination of the first and second polyolefin fractions can produce a polymer resin fluff having bimodal molecular weight distribution.

Abstract: A process for producing polyethylene having improved crack resistance, the process comprising copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, in the presence of a chromium-based catalyst in a first reactor, feeding the polyethylene copolymer thereby produced and the chromium-based catalyst to a second reactor, and in the second reactor copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms, in the presence of the chromium-based catalyst thereby to produce a second polyethylene product, the first and second polyethylene products forming a combined polyethylene having a monomodal molecular weight distribution.

Abstract: Process for the preparation of polyethylene by the homopolymerization of ethylene or by the copolymerization of ethylene and of at least one alpha-olefinic comonomer containing from 3 to 10 carbon atoms, in two reactors for loop polymerization in liquid phase which are connected in series in the presence of a chromium catalyst, in which ethylene and the chromium catalyst are first introduced into the first reactor at a temperature of 95 to 110.degree. C. to produce an ethylene homopolymer of low molecular weight of a melt index MI.sub.2 of at least 1 g/10 minutes and in which the ethylene homopolymer thus obtained is next transferred into the second reactor to which ethylene and optionally the alpha-olefinic comonomer is added, at a temperature of 80 to 90.degree. C. to obtain an ethylene copolymer of high molecular weight.

Abstract: In a process for the copolymerization of ethylene in two liquid full loop reactors in series wherein the average molecular weight is regulated, the introduction of the comonomer is made in the first reactor, and high and low average molecular weight polymers are produced respectively in the first and second reactor, the improvement which consists in using one or more settling legs of the first reactor for the transfer.