Abstract: The technical field of the invention is that of manufacturing heat treatment apparatuses such as furnaces for thermally cracking chemical substances, in particular hydrocarbons.

Abstract: The technical field of the invention is the field of methods and apparatus for thermally cracking chemicals. The present invention provides a method and apparatus for measuring the vibration of a duct in which there flows at least one fluid and which is disposed inside a thermal enclosure at high temperature, wherein a vibration sensor is used that is located inside the enclosure.

Abstract: The invention concerns a process for the production of polyolefins with a wide range of distribution in respect of molecular masses.The process comprises polymerizing ethylene, which is optionally accompanied by one or more other olefins, in contact with a catalytic system comprising:(a) a catalyst comprising a solid compound of titanium, magnesium and a halogen such as chlorine or bormine(b) one or more organometallic compounds of a metal of groups II and III of the periodic table of elements(c) one or more halogenated ethylenic hydrocarbons.The resulting polyolefins are particularly suitable for being shaped by means of extrusion-blowing.

Abstract: PCT No. PCT/FR78/00008 Sec. 371 Date Mar. 22, 1979 Sec. 102(e) Date Mar. 22, 1979 PCT Filed July 10, 1978The invention concerns a process for preventing the formation of deposits on the walls of the heating or cooling circuits of heat exchangers in which an aqueous heat-exchange liquid circulates.This process comprises mixing with the heat-exchange liquids from about 0.3 to about 5% by weight of a product of polyaddition of ethylene oxide and propylene oxide on a monohydric alcohol, water, a diol or a triol, the ethylene oxide representing from 60% to 90% by weight of the fixed alkylene oxides.This process can be used in particular in internal combustion engine cooling circuits.

Abstract: Process and apparatus for assembling tubular components of metal or thermoplastic material by frictional welding in which use is made of a short tubular connecting cuff placed between the end surfaces to be assembled of the two tubular members held in alignment with said cuff and which is rotated about an axis perpendicular to the surfaces to be welded while regulating the position of the cuff along the axis until uniform softening by friction is obtained of the contacting surfaces, the rotation of the cuff is then stopped while maintaining a pressure on the tubes until the weld is consolidated upon cooling.The apparatus is characterized by the fact that thrusts independent of one another are exerted between the cuffs and tubes so as to produce pressure contact between the two ends of the cuffs and corresponding ends of the tubes.

Abstract: The dry polymerization of olefins to produce polymers having a molecular weight above 50,000 in the presence of a catalyst system formed of a compound of a transition metal and a co-catalyst of an organo-metallic compound of a metal of Groups II or III of the periodic table, in which the polymerization reaction is carried out in a series of reaction vessels wherein the formed polymer is transferred from one to the other and in which additional co-catalyst is added to reaction vessels beyond the first, the gaseous effluent from each reaction vessel is recycled back to the reaction vessel and in which the co-catalyst is introduced into the first reaction vessel in an amount such that the atomic ratio of the metal of the co-catalyst to the transition metal is within the range of 0.1 to 10, and in which the co-catalyst is introduced into vessels other than the first in an amount such that the atomic ratio of metal of the co-catalyst to the transition metal is within the range of 0.1 to 20.

Abstract: A method for the polymerization of olefins using a catalyst in the form of a solid compound of a transition metal in which the transition metal is at least partially reduced to a valency state lower than the maximum valency state, with the transition metal compound being subjected prior to use to pre-activation by contact with magnesium and one or more halogenated hydrocarbons and one or more organo-metallic compounds of Groups II and III.

Abstract: The polymerization of olefins to form polymers having a molecular weight greater than 50,000 wherein the polymerization is carried out in the presence of a catalyst component formed of a compound of a transition metal of the sub-groups IVa, Va and VIa, and a co-catalyst component of at least one organo-metallic compound of a metal from groups II and III of the periodic table, in which the co-catalyst is in the form of a liquid which is separately introduced into the reaction vessel on a carrier formed of an inert porous powder which is impregnated with the co-catalyst.

Abstract: The method of polymerizing olefins which includes the preparation of a pre-activated compound of a transition metal of IVa, Va and VIa of the periodic table of elements, in which the transition metal is at least partially in a reduced valency state, in which the pre-activation is carried out by contacting the transition metal compound with an organomagnesium compound and then polymerizing the olefins in the presence of the pre-activated transition metal compound and an organo-aluminum compound.

Abstract: A method for producing solid polymers having a molecular weight greater than 50,000 from olefins wherein the olefin is polymerized in the absence of a liquid dispersion agent of a nature different from that of the olefin to be polymerized, and in contact with a prepolymer containing a small amount of transition metal of subgroups IV-b, V-b and VI-b having been produced by the polymerization of an olefin in a dispersion liquid containing a Ziegler-type catalyst.

Abstract: Atactic waxes and method for preparing same by polymerization of polyolefin alone or in combination with other monoolefins of the formula CH.sub.2 = CHR in which R is hydrogen or an alkyl radical having from 2 to 8 carbon atoms in which the polymerization is carried out at low pressure and in a hydrocarbon solvent in the presence of a catalyst formed of the product of the reaction of magnesium or a compound thereof, a compound of a transition metal selected from the sub-groups IVa, Va and VIa of the periodic classification of elements and an alkyl halide, and a co-catalyst in the form of an organometallic compound of a metal selected of groups II and III of the periodic classification of elements.