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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0053—Details of the reactor
  • B01J19/006—Baffles
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/245—Stationary reactors without moving elements inside placed in series
• • 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
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/24—Stationary reactors without moving elements inside
  • B01J19/2455—Stationary reactors without moving elements inside provoking a loop type movement of the reactants
  • B01J19/246—Stationary reactors without moving elements inside provoking a loop type movement of the reactants internally, i.e. the mixture circulating inside the vessel such that the upward stream is separated physically from the downward stream(s)
• • 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
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00054—Controlling or regulating the heat exchange system
  • B01J2219/00056—Controlling or regulating the heat exchange system involving measured parameters
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
  • B01J2219/00076—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements inside the reactor
  • B01J2219/00083—Coils
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00051—Controlling the temperature
  • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
  • B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
  • B01J2219/00094—Jackets
• • 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
  • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J2219/00049—Controlling or regulating processes
  • B01J2219/00164—Controlling or regulating processes controlling the flow
  • B01J2219/00166—Controlling or regulating processes controlling the flow controlling the residence time inside the reactor vessel

Definitions

• the invention pertains to a reactor system for conducting a pre- condensation in the production of polyester.
• the invention also pertains to a method for producing a polyester pre-condensate.
• Polyesters such as Polyethylene Terephthalate (PET) are produced in batch as well as continuous processes, starting from a glycol (e.g.: Ethylene Glycol) and a di-basic acid (e.g.: Terephthalic Acid) or the corresponding methyl ester (e.g.: Dimethyl Terephthalate).
• a glycol e.g.: Ethylene Glycol
• a di-basic acid e.g.: Terephthalic Acid
• Dimethyl Terephthalate Dimethyl Terephthalate
• the first reaction serves to transform the starting materials into a pre-condensate ("monomer") releasing water (direct esterification reaction from the acid) or methanol (ester interchange reaction from the dimethylester).
• the second reaction stage is a polycondensation under vacuum, where the pre- condensate is transformed into a polymer.
• the above-mentioned first stage is normally conducted in two steps, and in at least two vessels, where the first step is under a pressure higher than the second.
• the two vessel are compacted in a single reactor multiple stage.
• the first step can be with or without mechanical agitation
• the transfer to the second stage (vessel) can be with or without pump
• the second stage (vessel) can be with or without mechanical agitation.
• one or more mechanical pumps, and/or mechanical stirrers are required to transfer the pre-condensate to the next stage. It is desired to reduce, and preferably avoid, the presence of such mechanical equipment.
• the need to install such equipment generally goes with higher investment and operational costs, as well as with problems in handling the reaction mixture which, ultimately, could adversely affect product properties.
• a reactor system for the production of polyester pre-condensate comprising at least two reaction zones, operating at substantially different pressure, wherein a first reaction zone comprises a first reactant feeding zone, a heat exchanger, preferably comprising a vapor condensing system and a jacket, and a first product discharge zone comprising a flow line to a second reaction zone; said second reaction zone comprises a second reactant feeding zone, a second product discharge zone and an internal heat exchanger, preferably a heating coil, wherein the second product discharge zone comprises an elevated inlet extending to above the lowest point of the second reaction zone, and a plurality of substantially concentric, preferably cylindrical, spacers surrounding the elevated inlet of the discharge zone, wherein the spacers are arranged so as to provide an increased path length between the reactant feeding zone and the product discharge zone, and wherein the elevated inlet of the product discharge zone is situated above the internal heat exchanger.
• the invention pertains to a process for the production of a polyester pre-condensate, comprising the following steps: (a) feeding a dihydric alcohol and a dicarboxylic acid or ester into the first zone of a reactor system as defined above so as to provide a reaction mixture;
• Figure 1 is a schematic drawing representing one embodiment (denoted "A") of a system according to the invention.
• Figures 2-6 similarly are schematic drawings representing, respectively, embodiments B-F of the invention.
• the invention presents a reactor set-up that serves to address a good conversion of the reaction mixture, as well as a good homogeneity to the outlet (pre-condensate), together with a reduction of energy requirements, and particularly allowing to use a minimum number of mechanical (rotating) devices. Further, the invention provides a compact design for a vertical reactor. Specifically the elimination of the agitator devices in the
• esterification stage 2 in the corresponding vertical room requires the insertion of the following internals.
• the first and second reaction zones are preferably placed in a vertical arrangement such that the first reaction zone comprises a separate lower vessel, and the second reaction zone comprises an upper vessel, i.e.
• the inlet of the second reaction zone is situated above the above- mentioned jacket.
• the inlet is in the form of a dip pipe extending from near the top of the vessel to the bottom of the vessel.
• the outlet of the dip pipe is positioned just below the liquid level of the reaction mixture.
• the initial esterification mixture is heated by means of an internal heat exchanger.
• spacers are provided that force the reaction mixture to reside for a sufficiently long time in the second reaction zone, so as to complete the conversion of the initial esterification mixture into a proper low-mole-weight polyester pre-condensate (preferably having a degree of polymerization of 8- 10).
• the spacers are provided in a concentric arrangement, so as to not only account for the aforementioned residence time, but also for a sufficient (non- mechanical driven) agitation so as to provide homogeneity of the reaction mixture.
• the spacers serve to create the conditions of a symmetric radial flow path for the reacting mixture, avoiding the formation of dead spots without the use of any mechanical agitation.
• the spacers serve to force the pre-condensate into a symmetric path directed to the center of the reactor.
• This inlet preferably comprises a funnel.
• the funnel is preferably designed with jagged edges.
• the product discharge zone preferably comprises a standpipe, with the inlet of the standpipe arranged as defined above.
• the concentric spacers preferably take the form of a weir (i.e. a barrier) that is designed so as to have an external weir designed with an opening cut located in the upper part opposite (i.e. at 180°) to the inlet of the discharge zone.
• the inner weir is preferably designed with an opening cut located in the bottom part, at 180° (opposite) to the external weir opening cut.
• the internal heat exchanger in the second reaction zone can be provided in any form providing a heating surface, but preferably comprises one or more heating coils.
• Such coils are preferably metal coils heated by a liquid heat transfer medium, or are embodied in an external built-in boiler-jacket.
• both the top and bottom part of the reactor can vary as is well known by the person skilled in the art.
• both the top and bottom part of the reactor are of a simple cylindrical type with or without an integrated heat exchanger.
• the reactant feeding zone is typically in the form of a dip pipe extending from the top or the side of the vessel down to below the liquid level.
• the bottom of the dip pipe will be preferably positioned at least 5 cm, more preferably at least 10 cm, most preferably at least 20 cm below the liquid level of the reaction mixture in the in the reaction zone.
• the reactor system preferably is provided with a heat exchanging system taking the heat transfer medium (preferentially a eutectic mixture of diphenyl and diphenyl oxide) in vapor phase and condensing it on its walls: the release of the condensate from the heating surface in contact with the process back to the jacket is by gravity.
• the heat transfer medium preferentially a eutectic mixture of diphenyl and diphenyl oxide
• the invention in one aspect, pertains to a plant for the production of polyester, comprising a reactor system as described hereinbefore, wherein the product discharge zone comprises a fluid connection to a polycondensation reactor.
• a reactor system as described hereinbefore, wherein the product discharge zone comprises a fluid connection to a polycondensation reactor.
• the latter refers to any suitable reactor, as is generally known to the skilled person, wherein the actual polymerization takes place, wherein pre- condensate is reacted to as to remove excess glycol, and to increase molecular weight.
• the invention pertains to a process for the production of a polyester pre-condensate, comprising the following steps:
• the invention also pertains to a process for the production of a polyester, comprising preparing a low-mole-weight polyester pre-condensate as described above, and subjecting the pre-condensate to polymerization. This process is preferably conducted in a plant as defined hereinabove.
• the dihydric alcohol is preferably ethylene glycol
• dicarboxylic compound is preferably terephthalic acid.
• the pressure in the second reaction zone (e.g. a top part of an integrated reaction vessel) is preferably from 1.0 to 1.7 bar, preferably from 1.2 to 1.5 bar, more preferably from 1.3to 1.5 bar.
• the pressure in the first reaction zone (e.g. the bottom part of an integrated reaction vessel) is from 2.0 to 4.0 bar, preferably from 2.5 to 3.5 bar, more preferably from 2.9 to 3.1 bar.
• the temperature in the second reaction zone is from 260°C to 280 °C, preferably from 265°C to275 °C, more preferably from 268 °C to 272 °C.
• the temperature in the first reaction zone is from 250 °C to 270 °C, preferably from 255 °C to 265 °C, more preferably from 259 to 261 °C.
• the conversion of terephthalic acid (generally PTA, purified terephthalic acid) in the first reaction zone is generally from 88.0 to 92.0 %, preferably from 89.0 to 91.0 %, more preferably from 89.5 to 90.5 % .
• the conversion of PTA in the second reaction zone is from 96.0 to 99.0 %, preferably from 96.5 to 98.5%, more preferably from 97.0 to 98.0%
• Fig. l schematically depicts embodiment A: a two stage reactor, El and E2 are integrated into one reaction vessel.
• the drawing includes the following references:
• Boiling medium is an eutectic mixture of Diphenyl and Diphenyl Oxide.
• E-II has a separated heat exchanger (coils) in the reactor, and here the heat exchange medium is liquid HTM (a liquid heat transfer medium, typically a mixture of heavy organic components such as hydrogenated terphenyls).
• Fig.2 schematically depicts embodiment B. This is the same as above but In El flows are affected by forced convection with the addition of a circulation pump.
• the reference list for Fig. 2 is:
• Fig.3 (Embodiment C): same as embodiment A but the heat exchanger in El reactor is free convection built-in type (calandria).
• References: 1 Esterification stage I room
• Fig.4 (Embodiment D): same as embodiment B but the heat exchanger in E2 reactor is a surface directly connected with the built-in boiler/jacket. References:
• Fig.5 same as embodiment A but the heat exchanger in E2 reactor is a surface directly connected with the built-in boiler/jacket. References:
• Fig. 6 (Embodiment F): same as embodiment C but there are two separate built-in boilers: the lower for the El stage, the upper for the E2 stage The heat exchanger in E2 reactor is a surface directly connected with the upper built-in boiler/jacket. This last is considered the preferred embodiment. References:

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Polyesters Or Polycarbonates (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (1)

Family

ID=46548786

Family Applications (1)

Country Status (3)

Family Cites Families (10)

• 2012
  • 2012-06-29 EP EP12737910.5A patent/EP2726194A2/de not_active Withdrawn
  • 2012-06-29 CN CN201280026458.3A patent/CN103702752A/zh active Pending
  • 2012-06-29 WO PCT/NL2012/050464 patent/WO2013002643A2/en not_active Ceased

Non-Patent Citations (1)

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