Hoechst Aktiengesellschaft

Karl Kaiser

Bernhard Kuxdorf

Manfred Scholz

Alexander Ohorodnik

Kurt Wissel

Rudolf Wesselmann

Horst Semmler

Robert Willms

Polyolefins which are made by subjecting .alpha.-olefins to catalytic polymerization are freed from residual liquid hydrocarbons by means of steam and water. To this end, the invention provides:

Continuous removal of residual hydrocarbons from polyolefins

An apparatus for drying moist chlorinated polymers, which are separated from an aqueous suspension, comprises a centrifugal nozzle structure which has a discharge outlet associated with it and a fluidized bed drier provided with a closable discharge outlet. The discharge outlet of the centrifugal nozzle structure opens into the upper portion of the fluidized bed drier.

Apparatus for drying chlorinated polymers

A degassing column comprising a tubular shell provided with a plurality of apertured plates; the plates are vertically spaced within said shell; a gap uniform in width over the periphery is left between each plate and said shell; each of said plates is penetrated by at least one eccentrically arranged conduit comprising a draining shaft in the upper portion thereof and a feed shaft in the lower portion below the penetrated plate; the apertures in said plates have a diameter of less than 5 mm; and a surface portion of each plate underneath each conduit is impermeable, said impermeable surface portion being one to two times the cross-section of said conduit. More specifically, each plate is supported by a plurality of generally wedge-shaped mountings fastened to the inside of the shell, and by a ring which is level with the said mountings and is fastened to the inside of the shell, the ring being interrupted at least in the regions of the said mountings. A capping sleeve is slipped over each draining shaft. The capping sleeve comprises an upper portion whose cross-section is similar to that of the draining shaft, and a lower portion of larger cross-section, which lower portion overlaps and is securely connected to the upper portion.

Degassing column

The invention relates to an improved process, wherein polyolefins are freed from saturated liquid residual hydrocarbons with the aid of water and steam. The improvement comprises

Process and apparatus for the continuous removal of residual

Moist chlorinated polymers, which are separated from an aqueous suspension, are dried. To this end the moist polymers are pre-dried in a centrifugation zone and the pre-dried polymers are completely dried in a fluidization zone which is arranged downstream of the centrifugation zone and in which a bed of fluidized material is continually maintained. The apparatus used for carrying out the drying process comprises a centrifugal nozzle structure which has a discharge outlet associated with it and a fluidized bed drier provided with a closable discharge outlet. The discharge outlet of the centrifugal nozzle structure opens into the upper portion of the fluidized bed drier.

Process and apparatus for drying chlorinated polymers

Monomeric matter is removed from an aqueous dispersion of a polymer containing at least 50 weight % of polymerized vinyl chloride. To this end, the dispersion is introduced into the upper portion of a column provided with sieve plates and contacted therein for 10 seconds up to 20 minutes, under 600 up to 1200 mm Hg, with hot steam at 100.degree. up to 150.degree. C. flowing countercurrently with respect to the dispersion. The polymer dispersion so treated is removed from the column base portion; and a vaporous matter mixture issuing at the head of the column is condensed stagewise so as to recover an aqueous phase and the monomeric matter.

Process for continuously removing monomers from an aqueous dispersion of

An aqueous polymer dispersion containing approximately 1 to 60 weight % of solid polymer particles with an average size of 20 to 500 microns and 5000 to 15,000 ppm of monomer(s), is freed from monomeric material. More specifically, the aqueous dispersion is preheated to 60.degree. to 90.degree. C. and introduced continuously into an upper portion of a column accommodating a plurality of apertured trays disposed one above another of which each has at least one eccentric aqueous dispersion descent shaft. The aqueous dispersion is introduced at a rate of a 5 to 35 m.sup.3 per m.sup.2 of tray area per hour and contacted countercurrently with steam at 80.degree. to 150.degree. C., under 0.5 to 5 bars, and in a proportion of 30 to 100 kg of steam per m.sup.3 of dispersion, for a mean period of 1 to 30 minutes; the pressure drop for steam ascending through one tray in the column being lower than that which would occur upon the undesirable passage of steam through one of the said shafts. At the column base, aqueous dispersion freed from monomeric material is removed and a vapor mixture emerging at an upper level of the column, is condensed, and monomeric material and an aqueous phase are recovered therefrom.

Continuous removal of monomers from an aqueous dispersion of a polymer

Chlorinated polymers obtained by a filter-separation procedure, in a moist form, especially a water-containing moist form, are dried. To this end, the moist polymer is predried in a first fluidized-bed drying zone, this being continuously operated, and is thereafter further dried in one or more further fluidized-bed drying zones disposed downstream, of the said first drying zone.

Process for drying chlorinated polymers

In a degassing column with several perforated plates arranged over one another and at a distance from one another in a column housing there is left free, between each plate and the column housing, a gap which is as small as possible and is uniform over the periphery, and the apertures in the plates have a diameter of less than 5 mm. Each plate is penetrated by at least one eccentrically arranged draining shaft, and at least one eccentrically arranged feed shaft ends above each plate. Finally, below each feed shaft on the plate an area is impermeable which is at least as large as the cross-section of the feed shaft.

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Bruhl, Germany

Karl Kaiser