Societe Chimique Des Charbonnages-cdf Chimie

Guy Jouffroy

Pierre Durand

Bernard Martinot

Pierre Charlon

Polyethylene is produced in at least one reactor under a pressure of 800 to 2500 bars and a temperature of 150.degree. to 350.degree. C., and the reaction mixture exiting the reactor through an expansion valve and supplied to a separator under a pressure of 50 to 400 bars is cooled by passing a flow Q of the mixture through a turbine. The turbine comprises at least one stage with a fixed nozzle and a bladed wheel having a rotation speed of between 12,000 and 40,000 r.p.m. Ethylene discharged from the separator is recycled to the inlet of a compressor, and the discharge from the compressor is supplied to the reactor.

Energy-saving process for manufacturing polyethylene and the related

Energy-saving device for manufacturing polyethylene

The danger of explosion due to decomposition of high-pressure industrial process gases, such as ethylene, is reduced by maintaining in an inert atmosphere at least part of an evacuation system included between a pressurized vessel within which the decomposition may take place, on the one hand, and the atmosphere, on the other. The evacuation system to the atmosphere for the gases contained in the high-pressure vessel, includes

Process for reducing the chances of ignition and explosion due to the

Process and device for cooling a mixture of polymer and monomer from a reactor in which ethylene is polymerized or copolymerized at a pressure greater than 1,000 bars between a pressure-reduction valve located downstream of the reactor and a medium pressure separator. The cooling is achieved by injecting monomer at a pressure below that of the separator using a device with a nozzle distance S.sub.1 and corresponding cross-section A.sub.1 the mixture from the reactor passes, a convergent mixing zone in which the mixture is mixed with the monomer injected, which is supplied at a flow rate q, and a diffuser of throat distance S.sub.3 and corresponding cross-section A.sub.3, which makes it possible to bring the mixture to the pressure of the separator. The dimensions of the device are such that the ratio Q/A.sub.1 is between 0.20 and 1.35 t/hr.mm.sup.2 and the ratio ##EQU1## is between 0.1 and 0.3 t/hr.mm.sup.2.

Process for the polymerization and copolymerization of ethylene, using a

Apparatus for reducing the chances of ignition and explosion due to the

Process and device for cooling a mixture of polymer and monomer from a reactor in which ethylene is polymerized or copolymerized at a pressure greater than 1,000 bars between a pressure-reduction valve located downstream of the reactor and a medium pressure separator. The cooling is achieved by injecting monomer at a pressure below that of the separator using a device with a nozzle cross-section S.sub.1 through which the mixture from the reactor passes, a convergent mixing zone in which the mixture is mixed with the monomer injected, which is supplied at a flow rate q, and a diffuser of throat cross-section S.sub.3, which makes it possible to bring the mixture to the pressure of the separator. The dimensions of the device are such that the ratio Q/S.sub.1 is between 0.20 and 1.35 t/hr.mm2 and the ratio (q+Q/S.sub.3 is between 0.1 and 0.3 t/hr.mm2.

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Lillebonne, France

Guy Jouffroy