Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D1/00—Evaporating
  • B01D1/06—Evaporators with vertical tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D1/00—Evaporating
  • B01D1/04—Evaporators with horizontal tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D19/00—Degasification of liquids
  • B01D19/0021—Degasification of liquids by bringing the liquid in a thin layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/008—Liquid distribution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/12—Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/50—Details of extruders
  • B29C48/76—Venting, drying means; Degassing means
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F6/00—Post-polymerisation treatments
  • C08F6/001—Removal of residual monomers by physical means
  • C08F6/003—Removal of residual monomers by physical means from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/07—Flat, e.g. panels
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S159/00—Concentrating evaporators
  • Y10S159/10—Organic
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S159/00—Concentrating evaporators
  • Y10S159/15—Special material

Definitions

• the invention relates to a strand evaporator with a degassing container, a product inlet with at least one distributor pipe, a product distributor, a product outlet and a vapor outlet.
• Such strand evaporators are used in particular in polymer production to remove the volatile constituents from the product stream (see, for example, R.J. Albalak, "Polymer Devolatilization", Marcel Dekker Inc., 1996, p. 8). Attempts are made to divide the heated product stream (e.g. liquefied polymer free-falling) into as many (polymer) strands as possible within the degassing container in order to achieve the highest possible surface area. Thin strands enable more strands to be accommodated per unit area. The string length and thus the height of the degassing container should, however, remain within reasonable limits.
• Perforated plates must be very strong due to the required product pre-pressure to reliably prevent them from sagging.
• a larger plate diameter requires longer holes in the perforated plate, so that the product pre-pressure rises to even higher values, which in turn affect the required plate thickness.
• Due to the limited product throughput in plate distributors a strand evaporator provided with such a plate distributor cannot be used arbitrarily enlarge, in particular high polymer throughputs (> 10 t / h) are not possible for most polymers with their typically high melt viscosity.
• the invention is therefore based on the object of designing and developing a strand evaporator mentioned at the outset and described in more detail above, in such a way that, especially in large production plants, an optimum occupancy density
• a strand evaporator device which has at least one degassing container, a product inlet, a product distributor, a product outlet and a vapor outlet, characterized in that the product distributor is designed as a pipe distributor with at least one distributor pipe and with a plurality of nozzle pipes arranged in parallel, which have a plurality of openings in the tube wall.
• the product distributor is designed as a pipe distributor with at least one distributor pipe and with a plurality of nozzle pipes arranged in parallel, which have a plurality of openings in the tube wall.
• Nozzle pipes arranged in several levels one above the other and offset from one another.
• the inventive arrangement of the individual pipes in the degassing tank allows an optimally uniform and dense distribution of the product strands over the Cross section of the container take place so that the volume of the degassing container can be fully utilized.
• there are also advantages for the vapor guidance since the volatile constituents of the product stream can be removed without any design effort above the product outlet and thus the risk of a strand deflection by side extraction is eliminated.
• the volatile constituents can flow countercurrent to the freely falling strands and upward in the edge region of the container.
• nozzle tubes are laterally spaced, regardless of whether they are arranged in one plane or in several superimposed planes.
• the individual tubes can have a (circular) round or oval cross-section, each with openings directed downwards (e.g. bores).
• openings directed downwards e.g. bores.
• a combination of such and the tube shapes mentioned below can also be expedient.
• the individual tubes are designed as half tubes, each of which is directed downwards through one, in particular a flat
• Perforated plate are limited. In this way, almost the entire diameter of the half-tubes can be used to form strands.
• the plate thickness of the half pipes or wall thickness of the oval pipes required for strength reasons can be considerably smaller than the plate thickness in conventional plate distributors.
• a triangular or rectangular cross section can be realized from thick-walled sheets or drawn profiles.
• Another special embodiment of the invention provides that the nozzle pipes, in particular falling towards their ends, are arranged inclined to the horizontal in order to ensure an angle ⁇ of up to 15 °, in particular 10 °, in order to ensure that the pipes run empty when the product feed is switched off ,
• the nozzle tubes are attached directly to the distributor tube of the product entry, so that in the
• connection can be made by welding or releasable attachment e.g. can be achieved by means of flange and screws.
• a further special embodiment of the invention provides that the ends (endings) of the nozzle pipes are made acute-angled by chamfering in order to minimize the dead space at the pipe end.
• the product distributor has a plurality of distributor pipes which are arranged in the degassing container, so that the product stream is divided into partial streams within the degassing container.
• the distributor pipe can run in a curved manner in the inner upper region of the degassing container.
• the product distributor it is also possible for the product distributor to have a plurality of distributor pipes located outside the degassing container, so that the product stream is divided into partial streams outside the degassing container.
• This alternative embodiment has the advantage that, if necessary, a single blocked pipe can be replaced with less effort than with “internal distributors”
• the advantage is paid for with the disadvantage of more complex sealing (vacuum resistance).
• a further special embodiment of the invention provides that the nozzle pipes of the pipe distributor are provided with additional heating pipes.
• This configuration also has great advantages in terms of product quality. Because, for example, significant in the production of polycarbonate, the temperature in the preliminary stage can be reduced, since the energy input required to heat the polycarbonate stream to the degassing temperature can only be realized "at the last moment". The pretreatment of the product makes the color of such polymers and thus improving product quality.
• a further preferred embodiment of the invention provides that the heating tubes are designed as half tubes, possibly with a smaller diameter than the nozzle tubes, and are applied to the nozzle tubes from above.
• Such an embodiment is structurally relatively complex, but this increased effort can be easily compensated for by the advantages associated with it.
• other cross-sections can also be used, in particular those with an oval cross-section.
• All parts in contact with the product flow can be made from any material.
• these parts are preferably made of a low-iron material with an iron content of at most 10% if, for example, iron-catalyzed heat-induced decomposition of the product results, as has been observed with polycarbonate. All products in contact with the product are particularly preferred
• alloys such as AUoy 59 (2.4605), Inconell 686 (2.4606), Alloy-B2, Alloy-B3, Alloy-B4, Alloy-C22, Alloy-C276, Alloy-C4 or Alloy 625.
• materials with high thermal conductivity are particularly preferred.
• a preferred embodiment of the strand evaporator is characterized in that the openings are arranged in a plurality of parallel rows along the nozzle tubes, the adjacent rows having a center distance of 1.0 to 20 mm, preferably 2.0 to 10 mm.
• the respectively adjacent rows of openings along the tube length are particularly preferably offset from one another.
• the adjacent openings in a row have a center distance of 1.5 to 20 mm, preferably 2 to 10 mm, from one another.
• the diameter of the openings is preferably from 0.1 to 10 mm, particularly preferably from 0.5 to 5 mm, very particularly preferably 1 to 3 mm.
• the openings in the nozzle tubes are preferably drilled.
• the bores are preferably carried out in such a way that the surface roughness of the bores is not too high, so that the roughness value R a is at most 12.5 ⁇ m.
• Roughness classes N6 to N9 according to ISO 1302 for the holes have proven to be particularly favorable.
• the preferred deburring of the bore ends is important for producing a stable polymer strand. Lowering the holes at the outlet is particularly advantageous for some polymers.
• the countersink angle is preferably in the range from 60 to 120 °. A countersink angle of approximately 90 ° is particularly preferred.
• the nozzle tubes are therefore provided with openings with an enlarged diameter in the direction of the polymer flow in order to achieve a largely constant throughput per opening.
• the throughput along the nozzle tubes is evened out through the openings through a different number of openings per unit length of the nozzle tube.
• the pressure gradient along the nozzle tubes is reduced and thus the throughput per opening is evened out. This prevents the throughput at individual openings from becoming so low that the polymer threads emerging at the openings tear off when the overall throughput is low. The degassing performance then fell.
• the strand evaporator according to the invention can be used to remove volatile components from solutions of any liquid or meltable polymers and similar substances.
• the volatile components in addition to the solvent can be non-polymerized monomers or oligomers as well as other low molecular weight starting materials.
• the invention furthermore relates to the use of the strand evaporator according to the invention for removing volatile constituents, in particular
• Solvents and / or monomers or oligomers from melts or solutions gene of thermally sensitive substances, in particular of polymers, medicinal substances, natural substances or food.
• the strand evaporator according to the invention is preferably used for degassing thermoplastic polymers.
• These polymers include all plastics that become fluid under the influence of pressure and temperature. Examples include polycarbonate, polystyrene, polyphenylene sulfide, polyurethane, polyamide, polyester, polyacrylate, polymethyl (meth) acrylate, SAN resin and their copolymers and possible mixtures of the polymers.
• FIG. 1 shows the arrangement of the nozzle pipes of the pipe distributor, schematically in cross section in a perspective view
• FIG. 2 shows a variant of the pipe distributor from FIG. 1 in a side view
• Fig. 4 shows the object of Fig. 1 with heated tubes
• Fig. 6 is a schematic longitudinal section through the entire arrangement of the
• FIG. 7 shows a cross section through the strand evaporator according to FIG. 6.
• a strand evaporator is shown in cross section in FIG. 7.
• Product flows through the product entry 11 to the product distributor 17 from the distributor pipe 1 and the nozzle pipes 2 branching therefrom (see FIG. 6). The product stream emerges from the openings
• the nozzle tubes are arranged next to one another in one plane (see FIGS. 6 and 7).
• the product distributor of the strand evaporator is shown schematically in Fig. 1, the product flow through a manifold 1 of a plurality of individual in the
• Distributor tube 1 is fed to nozzle tubes 2, which are designed as half tubes 2 in the illustrated and in this respect preferred embodiment, and are closed at the bottom by perforated plates 3. It can quickly be seen that the fact that the individual nozzle tubes 2 are attached directly to the distributor tube 1 of the product entry means that no product dead spaces can arise in the distributor tube 1. In contrast to the embodiment according to FIG. 7, the nozzle tubes 2 according to FIG. 1 are arranged next to one another offset in two superposed planes.
• the nozzle pipes 2 preferably have a slight inclination to the horizontal in the direction of their ends and are also provided with a stopper 4 at their ends (see FIG. 2a) ,
• the improved occupancy density that is to say the product throughput per unit area, can be clearly seen from the schematic illustration in FIGS. 3a to 3d.
• tubes (“lances”) 7 which are spaced apart from one another are carried through the wall of the degassing container 6 and, in the test example, were nested into one another from two sides.
• 3c shows that the same number of bores can be accommodated on half the diameter of an internal distributor with the solution by means of offset half-tubes 2. This means that the assignment (number of holes per unit area) is four times as large as in the above arrangement. With a triangular arrangement of the bores, the densest possible assignment can be achieved.
• the minimum diameter is 1130 mm.
• FIG. 3 c shows a curved distributor pipe which has nozzle pipes 2 of different lengths in the bore area and thus different ones
• FIG. 3b Due to the throughputs per tube, a straight distributor tube 1 is shown in FIG. 3b, which leads to the same tube lengths and the same throughput per tube 2.
• the pipe distributor can have a central distributor pipe 1, from which nozzle pipes 2 branch in two directions.
• FIGS. 4 and 5 show that heating of the pipe distributor is also possible.
• a heating tube 8 is applied to the individual half-tubes 2, the diameter of which is slightly smaller than that of the half-tube 2 in order to avoid impairment.
• a heating medium is fed to the individual heating pipes in the direction of the arrow at inlet 9 and along the arrow at outlet
• the strand evaporator according to the invention leads to a high occupancy density and extremely high flexibility with regard to product throughput and material selection. Further advantages result from the manufacturing effort and the material availability, since the individual
• Pipes can be easily prefabricated. As already stated, the vapors can also be guided optimally, since the volatile constituents can be removed with the arrangement according to the invention of the individual tubes without any design effort above the product outlet.
• styrene-containing SAN copolymer with a content of approx. 2000 ppm of volatile compounds (styrene, acrylonitrile, ethylbenzene (solvent)) is evaporated. At a product temperature of 220 ° C, the viscosity is over 1000 Pa.s.
• a pipe distributor according to FIGS. 6 and 7 with half pipes lying in one plane (similar to FIG. 1 a) is used.
• the downward-closing half-tube plate 3 has a wall thickness of 25 mm.
• the holes 15 are stepped, they taper from 3 to 2 mm. In the area of the bore diameter of 3 mm, the average roughness value is R a
• the average roughness value R a is 1.6 ⁇ m.
• the bore ends are deburred and have a countersink. With a throughput of approx. 100 g per hour and bore, a strand evaporator with 6 m long polymer thread results in a residual volatile compound content of 100 ppm in the degassed product.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Dispersion Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Details Of Indoor Wiring (AREA)

Priority Applications (8)

Applications Claiming Priority (2)

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Cited By (7)

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Citations (4)

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• 1999
  • 1999-11-29 DE DE19957458A patent/DE19957458A1/de not_active Withdrawn
• 2000
  • 2000-11-17 JP JP2001541583A patent/JP2004502564A/ja not_active Withdrawn
  • 2000-11-17 EP EP00976044A patent/EP1242156B1/de not_active Expired - Lifetime
  • 2000-11-17 AU AU13951/01A patent/AU1395101A/en not_active Abandoned
  • 2000-11-17 BR BR0015935-2A patent/BR0015935A/pt not_active Application Discontinuation
  • 2000-11-17 US US10/130,757 patent/US6780281B1/en not_active Expired - Fee Related
  • 2000-11-17 WO PCT/EP2000/011468 patent/WO2001039856A1/de not_active Ceased
  • 2000-11-17 ES ES00976044T patent/ES2248145T3/es not_active Expired - Lifetime
  • 2000-11-17 MX MXPA02005297A patent/MXPA02005297A/es unknown
  • 2000-11-17 KR KR1020027006793A patent/KR100677792B1/ko not_active Expired - Fee Related
  • 2000-11-17 DE DE50011659T patent/DE50011659D1/de not_active Expired - Lifetime
  • 2000-11-17 CN CNB008164118A patent/CN1224440C/zh not_active Expired - Fee Related
  • 2000-11-28 TW TW089125166A patent/TW523422B/zh not_active IP Right Cessation

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