WO2005068063A9 - Procede et appareil de refroidissement de polymeres - Google Patents

Procede et appareil de refroidissement de polymeres

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Publication number
WO2005068063A9
WO2005068063A9 PCT/US2004/000144 US2004000144W WO2005068063A9 WO 2005068063 A9 WO2005068063 A9 WO 2005068063A9 US 2004000144 W US2004000144 W US 2004000144W WO 2005068063 A9 WO2005068063 A9 WO 2005068063A9
Authority
WO
WIPO (PCT)
Prior art keywords
gas
section
reactor
dispensing section
polymer solids
Prior art date
Application number
PCT/US2004/000144
Other languages
English (en)
Other versions
WO2005068063A1 (fr
Inventor
James F Mcgehee
Guiseppina R Boveri
Paul A Sechrist
Original Assignee
Uop Llc
James F Mcgehee
Guiseppina R Boveri
Paul A Sechrist
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Uop Llc, James F Mcgehee, Guiseppina R Boveri, Paul A Sechrist filed Critical Uop Llc
Priority to EP04700380A priority Critical patent/EP1701783A1/fr
Priority to BRPI0418356-8A priority patent/BRPI0418356A/pt
Priority to CNA2004800423119A priority patent/CN1925907A/zh
Priority to PCT/US2004/000144 priority patent/WO2005068063A1/fr
Publication of WO2005068063A1 publication Critical patent/WO2005068063A1/fr
Publication of WO2005068063A9 publication Critical patent/WO2005068063A9/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/005—Separating solid material from the gas/liquid stream
    • B01J8/006—Separating solid material from the gas/liquid stream by filtration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/1836—Heating and cooling the reactor
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C08G63/785—Preparation processes characterised by the apparatus used
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C08G63/80—Solid-state polycondensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00327—Controlling the temperature by direct heat exchange
    • B01J2208/00336—Controlling the temperature by direct heat exchange adding a temperature modifying medium to the reactants
    • B01J2208/00353—Non-cryogenic fluids
    • B01J2208/00371—Non-cryogenic fluids gaseous
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00548—Flow
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16—Dicarboxylic acids and dihydroxy compounds
    • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/181—Acids containing aromatic rings
    • C08G63/183—Terephthalic acids

Definitions

  • the present invention relates to a process for cooling or heating polymer in a polymerization reactor.
  • the invention specifically relates to cooling polymerized solids in a polycondensation reactor.
  • the invention particularly relates to cooling polyester, polyamide or polycarbonate chips in a solid-state polycondensation (SSP) reactor.
  • SSP solid-state polycondensation
  • PET resins Polyethylene terephthalate (PET) resin.
  • PET polyethylene terephthalate
  • aromatic polyester resins particularly PET, copolymers of terephthalic acid with lower proportions of isophthalic acid and polybutylene terephthalate are used in the production of beverage containers, films, fibers, packages and tire cord.
  • SSP solid-state polycondensation or polymerization
  • the intrinsic viscosity of the resin must generally be between 0.6 and 0.75 dl/g, higher values are necessary for molding materials such as containers and tire cord. Higher intrinsic viscosity such as greater than 0.75 dl/g can only with difficulty be obtained directly through polycondensation of molten PET, commonly called the melt phase process.
  • the SSP process pushes polymerization to a higher degree thereby increasing the molecular weight of the polymer by the heating and removal of reaction products.
  • the polymer with higher molecular weight has greater mechanical strength and other properties useful for production of containers, fibers and films, for example.
  • the SSP process starts with polymer chips that are in an amorphous state.
  • US-A- 4,064,112 Bl teaches crystallizing and heating the chips in a crystallizer vessel under agitation to a density of 1.403 to 1.415 g/crn ⁇ and a temperature ranging between 230° and 245°C (446° and 473°F) before entering into the SSP reactor. Otherwise the tacky chips tend to stick together.
  • the SSP reactor may consist of a cylindrical reactive section containing a vertical mobile bed into which the polymer chips are introduced from above and a frusto-conical portion of a dispensing section at the base for dispensing the product chips
  • the polycondensation reactor typically operates at temperatures between 210° and 22O 0 C (410° and 428 0 F)
  • the polyester chips move through the cylindrical reactive section of the polycondensation reactor by gravity in plug-flow
  • the chips enter the frusto- conical portion of the dispensing section at the base of the polycondensation reactor, they enter into a non-flat velocity profile which interjects a non-uniformity in the amount of time that the chips are in the polycondensation reactor Accordingly, a chip-to-chip variation in the degree of polymerization occurs due to the variation in residence time
  • the chips are subjected to a consolidation pressure that may be several times the normal radial axial pressure
  • Inert gas such as nitiogen is intioduced into the crystallizer vessel and the polycondensation reactor to strip the developing polymer of volatile impurities generated by the polycondensation reaction
  • Impurities include ethylene glycol and acetaldehyde if PET is produced
  • US-A-5,708,124 B l discloses maintaining the ratio of the mass flow rate of inert gas to the mass flow rate of PET polymer solids to below 0 6 in an SSP reactor
  • the conventional method used for the purification of an inert gaseous stream recycled from an SSP process includes an oxidation step for converting the organic impurities to CO 2 and a drying step to eliminate the water formed in the polymerization process and the oxidation step.
  • the oxidation step is carried out with gas containing oxygen by using an oxygen concentration of no more than in slight excess of the stoichiometric quantity with respect to the organic impurities.
  • the oxidation step is controlled according to US-A-5,612,011 Bl so that the inert gaseous stream at the outlet contains an oxygen concentration of not more than 250 ppm and preferably according to TJS-A-5, 547,652 B 1 so that the inert gaseous stream at the outlet contains an oxygen concentration of not more than 10 ppm.
  • PA6,6, PAl 1, PA12 and their copolymers find wide application both in the fiber and flexible packaging sectors, and in the manufactured articles production by blow and extrusion technology. While the resin relative viscosity for fibers is low at 2.4 to 3.0, higher relative viscosities of 3.2 to 5.0 are needed for articles produced by blow and extrusion technologies. The relative viscosity is increased to above 3.0 by means of an SSP process operating at temperatures of between 140° and 230 0 C (284° and 446 0 F), depending on the polyamide types used. US-A-4,460,762 B 1 describes an SSP process for a polyamide and different methods to accelerate this reaction.
  • the molecular weight of polycarbonate can be increased through an SSP process.
  • the polymer chips exiting from an SSP reactor must be cooled to below the glass transition temperature for packaging purposes, especially to avoid heat damage to packaging containers, such as sacks and boxes.
  • the desired packaging temperature is below 80 0 C (176 0 F) for PET chips.
  • US-A-5, 817,747 B l teaches two-stage cooling of the polymer chips after exiting the polycondensation reactor.
  • the first cooling stage is a bed fluidized with nitrogen used for purging impurities from the SSP process after the nitrogen has been purified.
  • the fluidizing gas entrains and separates the polymer dust from the polymer chips while cooling them to 160° to 180 0 C (320° to 356 0 F).
  • the polymer dust is formed in the processing apparatuses by the action of rotating parts of an agitator in contact with the polymer chips in the crystallizer vessel and the sliding friction between the chips and the walls of the polycondensation reactor.
  • the second cooling stage is a shell and tube or wall-type heat exchange cooler which uses water as the cooling fluid to cool the chips to between 40° and 6O 0 C (104° and 140 0 F).
  • US-A-5,662,870 Bl discloses a fluidized bed with two chambers for cooling polymer chips exiting the SSP reactor in a single stage. Fluidizing gas from the hotter chamber into which hot chips enter from the SSP reactor is recycled to heat the SSP reactor after it is de- dusted through a cyclone. Fluidizing gas from the cooler chamber is also de-dusted through a cyclone and recycled to the fluidizing bed. The amount of dust collected in the fluidizing gas from a fluidized bed is significant and must be removed.
  • JP 5-253468 Al teaches introducing a nitrogen gas into a vessel surrounding a dispensing cone at the bottom of a reaction chamber to indirectly cool a product, solid-gas mixture in the cone without causing turbulence within the cone.
  • Polietilentereftalato (1984-85) discloses an SSP reactor with nitrogen gas distributors located along the height of the reactor of which the bottom nitrogen distributor cools polyester chips to below a temperature at which oxidation can occur such as to 177 0 C (351 0 F). The chips would have to be subsequently cooled to lower temperatures to permit packaging.
  • a presentation by A. Christel entitled “Advanced PET Bottle-to-Bottle Recycling” given at the Polyester 2000 World Congress discloses directly cooling recycled PET flakes at an outlet of a hopper of an SSP reactor with cold nitrogen.
  • Cooling the polymer chips after exiting the polycondensation reactor requires at least one cooling device, a gas mover such as a fan and a dust removal device. Either this equipment has to be located beneath the reactor or a pickup point and pneumatic conveying means has to be used to carry the hot chips to the top of a cooling section.
  • a gas mover such as a fan and a dust removal device.
  • pneumatic conveying means has to be used to carry the hot chips to the top of a cooling section.
  • Each approach involves additional equipment and building costs.
  • the former approach requires a taller overall SSP complex.
  • US-A-4,255,542 Bl discloses an exothermic gas phase polymerization process in a fluidized bed reactor which is cooled by indirect cooling within the reactor.
  • US-A-3,227,527 B l discloses a catalytic reactor vessel in which product gas permeates a truncated cone section at the base of the reactor to be cooled by quench liquid before exiting the reactor. These patents do not involve direct cooling of polymer solids in a packed bed with a gas.
  • an object of the present invention is to eliminate the additional cooling equipment required to cool the chips to a packaging temperature after exiting the SSP reactor.
  • An additional object of the present invention is to consolidate the equipment used for cooling polymer solids and for introducing purge gas to the SSP reactor for the purging of impurities.
  • An additional object of the present invention is to cool the polymer chips entering the dispensing section of the SSP reactor and therefore make the dispensing section a non-reactive region and to prevent the hot, tacky polymer chips from lumping when they are subjected to the consolidation pressure upon entering the frusto-conical portion of the dispensing section.
  • An even further object of the present invention is to be able to eliminate the need for expensive dust removal equipment required with post-polycondensation reactor cooling equipment.
  • the present invention relates to an apparatus for
  • the apparatus comprises a reactor including a heated
  • the reactive section in which substantial polymerization of polymer solids therein occurs and a dispensing section for dispensing polymer solids from the reactor.
  • the dispensing section defines an interior volume preferably in a shape that reduces its flow area in the direction
  • a gas inlet connective with the interior volume of the dispensing section
  • the present invention relates to a process for cooling
  • process comprises delivering polymer solids to the top of the reactive section.
  • the polymer solids are polymerized as they flow downwardly in the reactive section so as to increase the molecular weight of the polymer solids.
  • the polymer solids are dispensed from the
  • the present invention relates to a process for
  • the process comprises delivering solids to a first section of the vessel.
  • the solids are
  • the heat capacity of the solids over a temperature range in the reactor is at least one.
  • FIG. 1 is a schematic view of a polymerization flow scheme of the present invention.
  • FIG. 2 is a partial, enlarged view of a reactor dispensing section and cooling apparatus of FIG. 1.
  • FIG. 3 is a partial, enlarged view of an alternative reactor dispensing section and cooling apparatus of FIG. 1.
  • FIG. 4 plots a temperature profile through the dispensing section of a reactor.
  • SSP solid-state polycondensation
  • the SSP process can be used to increase the intrinsic viscosity of polyester, polyamide and polycarbonate components.
  • the present invention may be used with other types of polymerization processes in which cooling of the polymer solid product is necessary.
  • Polyester resins usable in the SSP process are products of polycondensation of aromatic bicarboxylic acid, particularly terephthalic acid or its esters with diols with 1 to 12 carbon atoms such as ethylene glycol, 1,4-dimethylolcyclohexane and 1,4-butanediol.
  • Polyethylene terephthalate (PET) and polybutylene terephthalate are the preferred resins.
  • Polyester resins usable in the SSP process also may include elastomeric polyester resins, including segments deriving from polyethylene glycol, and copolyesters containing up to 20% of units deriving from aromatic bicarboxylic acids different from terephthalic acid, such as isophthalic acid.
  • PET resins to be subjected to SSP can contain a resin-upgrading additive to accelerate the SSP reaction.
  • the preferred upgrading compounds are the dianhydrides of tetracarboxylic aromatic acids, and particularly pyromellitic dianhydride.
  • the upgrading agent is generally used in a quantity of 0.05 to 2% by weight.
  • Conventional additives, like stabilizers, dyes, flame-retardants and nucleants can also be present in the resin.
  • Polyester resins useful for upgrading in SSP processes can also be material produced from recycled containers which have been washed, shredded and dried. Typically, the recycled material is remelted and pelletized before being sent to the SSP process.
  • Polyamide resins usable in the process of the invention include polyamide 6 derived from caprolactam, polyamide 6,6 obtained from hexamethylenediamine and adipic acid, polyamide 11 obtained from aminoundecanoic acid, and 12 polylaurilacetone copolyamides 6/10 and 10/12 and also polyamides of metaxylene diamine.
  • FIG. 1 is an example of an SSP process for upgrading PET chips with the present invention.
  • the SSP process in FIG. 1 can process up to 100 metric tons/day and more of polymer solids and typically 300 to 500 metric tons/day of polymer solids.
  • the polyester SSP process comprises feeding amorphous, clear polyester chips having an intrinsic viscosity usually ranging from 0.57 to 0.65 dl/g to a hopper 12 through a line 10.
  • the intrinsic viscosity or molecular weight of the starting material is immaterial to the practice of the invention.
  • the SSP process can be successfully performed with feeds across a wide range of values.
  • a starting material having a degree of polymerization as low as 2-40 by US-A-5,540,868 Bl, US-A-5,633,018 Bl and US-A-5,744,074 B l which contemplate eventually undergoing SSP processing to raise the molecular weight sufficient to make useful resins.
  • the starting intrinsic viscosity in the case of post-consumer recycle material can be at levels of above 0.65 dl/g.
  • the hopper 12 feeds the chips through a line 14 and a control valve 16 to a fluidized bed pre-crystallizer 18.
  • the pre- crystallizer 18 operates at 17O 0 C (338°F) and 10.3 kPa gauge (1.5 psig) to achieve 35%
  • crystallinity of the polyester chips are then fed from the pre-crystallizer 18 through a line 20 and a control valve 22 into a first crystallizer 24. If more capacity is necessary, a second crystallizer 28 may be utilized which the first crystallizer 24 feeds through a line 26.
  • the chips are eventually preheated or cooled in some cases to an SSP reaction temperature while subjected to mechanical agitation to prevent the chips from sticking to each other. The chips leaving the crystallizer will exhibit 45% crystallinity. Crystallizing PET granules prior to polycondensation prevents the granules from sticking during the SSP reaction.
  • the chips leaving the crystallizer(s) are then fed through a line 30 and a control valve 32 to a moving packed bed SSP reactor 34 operated suitably at 150° to 240 0 C (302° to 464 0 F) and preferably at 210° to 22O 0 C (410° to 428°F) for PET.
  • the chips move by gravity through a heated reactive section 70 in which polymerization occurs for 12 to 36 hours to yield crystalline, opaque pellets with an intrinsic viscosity of 0.75 dl/g or greater depending upon the application to which the polyester pellets will be put.
  • the chips are withdrawn from the reactor 34 through a line 36.
  • An oxygen-free inert gas typically nitrogen, purges the polymerization reactor, the crystallizers and the pre-crystallizer to remove impurities given off by the chips.
  • the inert gas is delivered through a line 38 into the reactor 34.
  • a gas line 42 removes inert gas with impurities from the reactor 34 and splits into a recycle line 44 and a crystallizer line 46.
  • the crystallizer line 46 delivers the inert gas to the second crystallizer 28 and a line 48 delivers inert gas from the second crystallizer 28 to the first crystallizer 24.
  • a line 50 delivers inert gas with impurities to the pre-crystallizer 18 and a line 52 delivers inert gas with impurities to join the recycle line 44.
  • the inert gas recycled in a combined recycle line 53 is preferably at a temperature between 200° and 22O 0 C (392° and 428°F).
  • the combined recycle line 53 runs the inert gas with impurities through a filter 54. After the recycled inert gaseous stream is filtered, air is injected by a line 57 into a line 56 exiting the filter 54.
  • the air/inert gaseous mixture is carried by a line 59 through a heater (not shown), if necessary to achieve the desired oxidation reaction temperature, into an oxidation reactor 58 where the organic impurities are combusted by circulating the stream over a catalyst bed including an oxidation catalyst.
  • Oxygen is injected by the line 57 in substantially stoichiometric quantities to assure the complete combustion of the organic impurities in the oxidation reactor 58.
  • the oxidation reactor 58 can be operated with these conversions at temperatures ranging from 200° to 35O 0 C (392° to 662 0 F) depending on the catalyst.
  • a line 60 withdraws the effluent from the oxidation reactor 58 that contains only nitrogen, carbon dioxide, water and traces of oxygen. The carbon dioxide content stabilizes at a certain level due to the losses through the SSP plant and acts like an inert gas due to its chemical inertia.
  • the exiting gaseous stream in the line 60 may be circulated through a heat exchanger (not shown) for heat recovery or to condense and dispose of part of the water by cooling the oxidation reactor effluent.
  • the gaseous stream is delivered by the line 60 to a dryer 62 preferably operating at 200 0 C (392 0 F).
  • the dryer 62 preferably contains molecular sieves for adsorbing the water.
  • the effluent of the dryer 62 is transported through a line 64 after having been filtered (not shown) of possible particles deriving from the molecular sieves.
  • the line 38 collects the combined contents of lines 64 and 74.
  • the line 38 recycles the gaseous stream to the reactor 34.
  • the regeneration of the molecular sieves bed is performed according to known methods (not shown).
  • the reactor 34 includes the heated cylindrical active or reactive section 70 that is preferably heated by a circulating oil jacket.
  • the reactor 34 also includes a dispensing or inactive section 72 comprising a cylindrical disengaging portion 88 and an inverted, generally frusto-conical consolidating portion 90.
  • the inert gas preferably nitrogen, enters an interior volume 91 defined by the dispensing section 72 through the line 38.
  • the inert gas directly cools the polymer solids in the dispensing section down to below 175 0 C (347°F), suitably below 100 0 C (212°F), preferably down to below 80 0 C (176 0 F) and perhaps to below 5O 0 C (122 0 F) if desired.
  • the cooled polymer solids can then be transported to storage through the line 36 without the need for any additional cooling equipment.
  • a portion of the inert gas is withdrawn from the reactor 34 proximate to the dispensing section 72 by a line 76 and enters a dust removal device 78.
  • Proximate to the dispensing section 72 means, the withdrawal point of the line 76 is either in the dispensing section 72 or not above the lower quarter of the reactive section 70 and preferably not above the lower tenth of the reactive section 70.
  • the de-dusted gas is transported from the dust removal device 78 through a line 80 and is moved by a fan 82 through a line 84 to a cooler 86 and is combined with the line 64 to be recycled to the dispensing section 72 of the reactor 34 by the line 38.
  • FIG. 2 gives a partial view of the reactor 34.
  • the cylindrical disengaging portion 88 has an inner diameter that is greater than the inner diameter of the reactive section 70.
  • Gas is withdrawn from the reactor 34 into line 76 through at least one outlet nozzle 92.
  • the outlet nozzle is preferably disposed in the disengaging portion 88 of the dispensing section 72. Although only one outlet nozzle 92 is shown in FIG. 2, a plurality of the radially disposed outlet nozzles 92 is contemplated. The remaining gas will ascend through the reactive section 70 of the reactor 34 and purge impurities stripped from the developing polymer.
  • the dust removal device 78 is either a dust-removing cyclone or a filter, which can operate continuously. The quantity of dust removed by the cooling gas flowing through the moving packed bed of polymer solids is low because it is only taken from the top-most layer of the polymer.
  • the cooler 86 removes the heat that the gas acquired in the dispensing section 72 by indirect heat exchange with a cooling medium such as water.
  • the flow rate of the gas removed proximate to the dispensing section 72 may be set by a variable capacity characteristic of the fan or by a control valve (not shown).
  • the excess inert gas equal to the flow of gas from the dryer 62 in the line 64, ascends into the reactive section 70 from the dispensing section 72.
  • Control valve 40 regulates the flow of gas through the line 64.
  • control valve 40 ensures that the mass flow ratio of gas to solids is less than 0.6, taking into account the gas removed from the reactor for cooling and recirculation.
  • the temperature of the ascending and withdrawn gas is set by the temperature of the gas fed to the dispensing section 72 plus the temperature rise caused by the removal of heat from the polymer solids.
  • the variable capacity fan 82 or a control valve can regulate the temperature of the polymer solids exiting the outlet 100 of the reactor 34. For example, setting the fan 82 or the control valve for a very low flow rate or no flow at all, raises the temperature of the gas in the line 38 since it mixes with less cooled gas from the line 74.
  • the polymer solids exiting the outlet 100 can have sufficient temperature for direct conveyance to a molding process such as injection molding which requires a polymer solids temperature above the glass transition temperature for moldability.
  • the flow rate of coolant circulated through the cooler 86 can regulate the temperature of solids exiting the reactor without affecting the flow rate of gas circulated through nozzles 92 and nozzle 96.
  • the inlet nozzle 96 distributes the gas via a ring distributor 98 in the form of annulus of a pipe (not shown) or annulus around the inside diameter of the dispensing section 72.
  • the ring distributor 98 has openings distributed radially around its circumference for distributing gas into the dispensing section 72.
  • the distributor Preferably the distributor not extend into the reactor 34 to avoid obstructing the flow of polymer solids.
  • FIG. 3 shows a different device for injecting the inert gas into the dispensing section 72 and that includes a control valve 94 in a bypass line 68.
  • a distributor 98' in FIG. 3 injects cooling gas around the periphery of the dispensing section 72 of the reactor 34.
  • the distributor 98' injects the cooling gas into the dispensing section 72 through perforations (not shown) in the wall of the dispensing section 72. Slots, bands or profile wire screen may define the perforations of distributor 98'.
  • the distributor 98' does not extend substantially into the reactor 34.
  • control valve 94 regulates the temperature of the polymer solids leaving the outlet 100.
  • a combined line 104 joins the line 64 from the dryer 62 and communicates with the inlet nozzle 96 via line 38.
  • Control valve 94 regulates the bypassing of gas through line 68 to control the temperature of the gas in the line 104 and ultimately line 38. Opening control valve 94 more cools less recirculating gas in the cooler 86 to reduce cooling of the solids and vice versa.
  • a temperature indicator controller (not shown) automatically regulate control valve 94 based on desired temperature of the solids exiting the outlet 100.
  • the local actual velocity of the cooling gas in all sections of the dispensing section not exceed 75% of the minimum fluidization velocity of polymer solids.
  • This preference primarily avoids agitation of the solids which may lead to flow mal-distribution and subsequent loss of cooling efficiency.
  • fluidization of the polymer solids may upset the mass flow of solids through disturbances in the bed which could lead to wider residence time distribution and variability in intrinsic viscosity.
  • a thermal mass ratio "R" be greater than or equal to 1.
  • the thermal mass ratio is as follows:
  • equation (1) can be reworked as follows:
  • Cooling is accomplished efficiently in the dispensing section 72 of the reactor 34 without wasting extra space or using additional equipment. Typically, the cooling equipment is below the reactor 34. Removing the conventional cooling equipment reduces capital cost and the overall height of the SSP. Alternatively, no pickup point is required to convey hot polymer solids to a cooling zone which is not situated below the polycondensation reactor.
  • the dispensing section of the present invention was tested in a pilot reactor of 618 mm inside diametei Nitrogen cooling gas was injected radially at a point in the frusto-conical portion of the dispensing section corresponding to a gas velocity of approximately 0 6 m/sec The cooling gas was withdrawn at the top of the frusto-conical portion of the dispensing section PET copolymer having an intrinsic viscosity of 0 6 dl/g was raised to 0 8 dl/g in the reactor and the product leaving the frusto-conical portion of the dispensing section had a temperature of approximately 45 0 C (113°F) The mass flow rate ratio of gas to solids in the dispensing section was 2 0 and the gas was injected at approximately 42°C (108 0 F) Pellet temperatures were measured by sliding a thermocouple approximately at centerline and the results were that the heat transfer was accomplished at slightly higher than 1 reactor diameter A plot of the temperature profile is shown in FIG 4 Because it was

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Other Resins Obtained By Reactions Not Involving Carbon-To-Carbon Unsaturated Bonds (AREA)
  • Polyesters Or Polycarbonates (AREA)

Abstract

L'invention concerne un procédé et un appareil qui permet de chauffer ou de refroidir des solides polymères dans une section de distribution (72) d'un réacteur de polycondensation à l'état solide (34). Un gaz (38) est fourni à la section de distribution du réacteur dans lequel il refroidit des polymères solides dans la section de distribution par échange thermique direct. Une partie du gaz est retirée au niveau d'un point (92) à proximité de la section de distribution du réacteur et est refroidie. Le reste du gaz monte dans une section de réaction du réacteur et purge les solides polymères de leurs impuretés. Les impuretés du gaz retiré de la section de réaction du réacteur sont oxydées et le gaz est séché et combiné au gaz retiré à proximité de la section de distribution du réacteur. Afin d'obtenir un chauffage ou un refroidissement uniforme des solides polymères dans la section de distribution, un rapport préféré débit massique du gaz sur débit massique des solides est recommandé.
PCT/US2004/000144 2004-01-06 2004-01-06 Procede et appareil de refroidissement de polymeres WO2005068063A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP04700380A EP1701783A1 (fr) 2004-01-06 2004-01-06 Procede et appareil de refroidissement de polymeres
BRPI0418356-8A BRPI0418356A (pt) 2004-01-06 2004-01-06 aparelho para conduzir um processo de polimerização, e, processo para resfriar sólidos poliméricos em um reator
CNA2004800423119A CN1925907A (zh) 2004-01-06 2004-01-06 冷却聚合物的方法和装置
PCT/US2004/000144 WO2005068063A1 (fr) 2004-01-06 2004-01-06 Procede et appareil de refroidissement de polymeres

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2004/000144 WO2005068063A1 (fr) 2004-01-06 2004-01-06 Procede et appareil de refroidissement de polymeres

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WO2005068063A1 WO2005068063A1 (fr) 2005-07-28
WO2005068063A9 true WO2005068063A9 (fr) 2006-09-14

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EP (1) EP1701783A1 (fr)
CN (1) CN1925907A (fr)
BR (1) BRPI0418356A (fr)
WO (1) WO2005068063A1 (fr)

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Publication number Priority date Publication date Assignee Title
US4197660A (en) * 1975-12-24 1980-04-15 Hoechst Aktiengesellschaft Process for crystallizing and drying polyethylene terephthalate and apparatus to carry out said process
US4223128A (en) * 1978-05-16 1980-09-16 Celanese Corporation Process for preparing polyethylene terephthalate useful for beverage containers
US4276261A (en) * 1979-07-16 1981-06-30 The Goodyear Tire & Rubber Company Polymerization apparatus and process
IT1285524B1 (it) * 1996-10-18 1998-06-08 Sinco Eng Spa Procedimento per il raffreddamento di resine poliestere e/o poliammidiche

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EP1701783A1 (fr) 2006-09-20
BRPI0418356A (pt) 2007-05-08
WO2005068063A1 (fr) 2005-07-28
CN1925907A (zh) 2007-03-07

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