WO2007103025A2 - Method and apparatus for drying carboxylic acid - Google Patents

Method and apparatus for drying carboxylic acid Download PDF

Info

Publication number
WO2007103025A2
WO2007103025A2 PCT/US2007/004935 US2007004935W WO2007103025A2 WO 2007103025 A2 WO2007103025 A2 WO 2007103025A2 US 2007004935 W US2007004935 W US 2007004935W WO 2007103025 A2 WO2007103025 A2 WO 2007103025A2
Authority
WO
WIPO (PCT)
Prior art keywords
drying
dryer
range
zone
wet cake
Prior art date
Application number
PCT/US2007/004935
Other languages
French (fr)
Other versions
WO2007103025A8 (en
WO2007103025A3 (en
Inventor
Kenny Randolph Parker
Philip Edward Gibson
Original Assignee
Eastman Chemical Company
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 Eastman Chemical Company filed Critical Eastman Chemical Company
Publication of WO2007103025A2 publication Critical patent/WO2007103025A2/en
Publication of WO2007103025A3 publication Critical patent/WO2007103025A3/en
Publication of WO2007103025A8 publication Critical patent/WO2007103025A8/en

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/18Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs
    • F26B17/20Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by rotating helical blades or other rotary conveyors which may be heated moving materials in stationary chambers, e.g. troughs the axis of rotation being horizontal or slightly inclined
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42Separation; Purification; Stabilisation; Use of additives
    • C07C51/47Separation; Purification; Stabilisation; Use of additives by solid-liquid treatment; by chemisorption
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B17/00Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement
    • F26B17/24Machines or apparatus for drying materials in loose, plastic, or fluidised form, e.g. granules, staple fibres, with progressive movement with movement performed by shooting or throwing the materials, e.g. after which the materials are subject to impact
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B21/00Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
    • F26B21/14Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects using gases or vapours other than air or steam, e.g. inert gases
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/041Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum for drying flowable materials, e.g. suspensions, bulk goods, in a continuous operation, e.g. with locks or other air tight arrangements for charging/discharging

Definitions

  • the present invention relates generally to a drying process for use in the production of a carboxylic acid. More specifically, the present invention concerns a method for drying solid particles of terephthalic acid in a drying zone where the residence time of the solid particles in the drying zone is reduced and the exit temperature of the solid particles is less than about 250 0 C. 2. Description of the Prior Art
  • CTA crude terephthalic acid
  • PTA purified terephthalic acid
  • TPA terephthalic acid
  • Such methods include the use of a rotary dryer, as well as drying the TPA wet cake by contacting it with a flow of inert gas, which can be achieved in a fluid bed dryer, a ring dryer, or in a solids conveying system.
  • a flow of inert gas which can be achieved in a fluid bed dryer, a ring dryer, or in a solids conveying system.
  • conventional methods for drying TPA can cause significant product degradation and/or sublimation, both of which are undesirable. Accordingly, there is a need for methods and/or equipment that can minimize product degradation and/or sublimation when drying a TPA product.
  • One embodiment of the present invention concerns a method for drying solid particles comprising a carboxylic acid.
  • the method of this embodiment comprises: (a) introducing a wet cake comprising the solid particles into a drying zone; and (b) drying the wet cake in the drying zone to thereby produce a substantially dry product comprising at least a portion of the solid particles, wherein the solid particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the solid particles have an exit temperature of less than about 250 0 C upon exiting the drying zone.
  • Another embodiment of the present invention concerns a method for producing a substantially dry crude terephthalic acid (CTA) particulate product.
  • the method of this embodiment comprises: (a) oxidizing an aromatic compound in an oxidation zone to thereby produce a slurry comprising solid CTA particles; (b) treating at least a portion of the slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of the solid CTA particles; and (c) drying at least a portion of the wet cake in a drying zone to thereby produce the substantially dry CTA particulate product, wherein the CTA particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the CTA particles have an exit temperature of less than about 250 0 C upon exiting the drying zone.
  • Yet another embodiment of the present invention concerns a method for producing a substantially dry purified terephthalic acid (PTA) particulate product.
  • the method of this embodiment comprises: (a) oxidizing an aromatic compound in an oxidation zone to thereby produce a first slurry comprising solid crude terephthalic acid (CTA) particles; (b) subjecting at least a portion of the CTA particles to purification in a purification zone to thereby produce a second slurry comprising solid PTA particles; (c) treating at least a portion of the second slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of the PTA particles; and (d) drying the wet cake in a drying zone to thereby produce the substantially dry PTA particulate product, wherein the PTA particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the PTA particles have an exit temperature of less than about 250 0 C upon exiting the drying zone.
  • CTA solid crude terephthal
  • Still another embodiment of the present invention concerns a method for drying a wet cake comprising terephthalic acid (TPA).
  • the method of this embodiment comprises: (a) introducing the wet cake into a dryer; and (b) drying the wet cake in the dryer to thereby produce a dry TPA product, wherein the TPA has an average residence time in the dryer of less than about 7 minutes, and wherein the dry TPA product has a temperature in the range of from about 105 to about 240°C upon exiting the dryer.
  • FIG. 1 is a process flow diagram illustrating a system for the production, purification, and drying of carboxylic acid constructed in accordance with the present invention, particularly illustrating a configuration where the crude slurry from the oxidation reactor is subjected to purification, the resulting purified slurry is subjected to product isolation, and the wet cake from the product isolation zone is subjected to drying in a drying zone;
  • FIG. 2 is a side view of a dryer that may be used in one embodiment of the present invention with certain sections being cut away to more clearly illustrate the operation of the dryer;
  • FIG. 3 is a sectional view of the dryer taken along line 3-3 in FIG. 2, particularly illustrating a rotor having a plurality of radial arms affixed thereto and paddles attached to each individual radial arm;
  • FIG. 4 is a weight percent vs. time plot depicting the thermal gravimetric analyses of purified terephthalic acid (PTA) in air, PTA in nitrogen, crude terephthalic acid (CTA) in air, and CTA in nitrogen, determined in accordance with the procedure described in Example 5; and
  • FIG. 4a is a magnified view of the plot depicted in FIG. 4, particularly illustrating the weight percent range from 95 to 100 and the time range from 185 to 285 of the weight percent vs. time plot depicted in FIG. 4.
  • FIG. 1 illustrates an embodiment of the present invention where carboxylic acid produced in an oxidation reactor and purified in a purification reactor is subjected to product isolation. A portion of the resulting wet cake from the product isolation zone is treated in a drying zone to thereby produce a substantially dry carboxylic acid particulate product.
  • Various embodiments of the drying zone are described in more detail below with reference to FIGS. 2 and 3. In the embodiment illustrated in FIG.
  • a predominately fluid-phase feed stream containing an oxidizable compound e.g., para-xylene
  • a solvent e.g., acetic acid and/or water
  • a catalyst system e.g., cobalt, manganese, and/or bromine
  • a predominately gas-phase oxidant stream containing molecular oxygen can also be introduced into oxidation zone 10.
  • the fluid- and gas-phase feed streams form a multiphase reaction medium in oxidation zone 10.
  • the oxidizable compound can undergo partial oxidation in a liquid phase of the reaction medium contained in oxidation zone 10.
  • oxidation zone 10 can comprise an agitated reactor. Agitation of the reaction medium in oxidation zone 10 can be provided by any means known in the art. As used herein, the term “agitation” shall denote work dissipated into the reaction medium causing fluid flow and/or mixing. In one embodiment, oxidation zone 10 can be a mechanically-agitated reactor equipped with means for mechanically agitating the reaction medium. As used herein, the term “mechanical agitation” shall denote agitation of the reaction medium caused by physical movement of a rigid or flexible element(s) against or within the reaction medium.
  • oxidation zone 10 can comprise a bubble column reactor.
  • bubble column reactor shall denote a reactor for facilitating chemical reactions in a multi-phase reaction medium, wherein agitation of the reaction medium is provided primarily by the upward movement of gas bubbles through the reaction medium.
  • major shall mean more than 50 percent.
  • the oxidizable compound present in the fluid-phase feed stream introduced into oxidation zone 10 can comprise at least one hydrocarbyl group.
  • the oxidizable compound can comprise an aromatic compound.
  • the oxidizable compound can comprise an aromatic compound with at least one attached hydrocarbyl group or at least one attached substituted hydrocarbyl group or at least one attached heteroatom or at least one attached carboxylic acid function (-COOH).
  • the oxidizable compound can comprise an aromatic compound with at least one attached hydrocarbyl group or at least one attached substituted hydrocarbyl group with each attached group comprising from 1 to 5 carbon atoms.
  • the oxidizable compound can be an aromatic compound having exactly two attached groups with each attached group comprising exactly one carbon atom and consisting of methyl groups and/or substituted methyl groups and/or at most one carboxylic acid group.
  • Suitable examples of the oxidizable compound include, but are not limited to, para-xylene, meta-xylene, para- tolualdehyde, meta-tolualdehyde, para-toluic acid, meta-toluic acid, and/or acetaldehyde.
  • the oxidizable compound comprises para-xylene.
  • a “hydrocarbyl group,” as defined herein, is at least one carbon atom that is bonded only to hydrogen atoms and/or to other carbon atoms.
  • a “substituted hydrocarbyl group,” as defined herein, is at least one carbon atom bonded to at least one heteroatom and to at least one hydrogen atom.
  • Heteroatoms as defined herein, are all atoms other than carbon and hydrogen atoms.
  • Aromaatic compounds as defined herein, comprise an aromatic ring and can comprise at least 6 carbon atoms and can also comprise only carbon atoms as part of the ring. Suitable examples of such aromatic rings include, but are not limited to, benzene, biphenyl, terphenyl, naphthalene, and other carbon- based fused aromatic rings.
  • the amount of oxidizable compound present in the fluid-phase feed stream introduced into oxidation zone 10 can be in the range of from about 4 to about 20 weight percent, or in the range of from 6 to 15 weight percent.
  • the solvent present in the fluid-phase feed stream introduced into primary oxidation reactor 10 can comprise an acid component and a water component.
  • the solvent can be present in the fluid-phase feed stream at a concentration in the range of from about 60 to about 98 weight percent, in the range of from about 80 to about 96 weight percent, or in the range of from 85 to 94 weight percent.
  • the acid component of the solvent can be an organic low molecular weight monocarboxylic acid having from 1 to 6 carbon atoms, or 2 carbon atoms.
  • the acid component of the solvent can comprise acetic acid.
  • the acid component can make up at least about 75 weight percent of the solvent, at least about 80 weight percent of the solvent, or in the range of from 85 to 98 weight percent of the solvent, with the balance being water.
  • the fluid-phase feed stream introduced into oxidation zone 10 can also include a catalyst system.
  • the catalyst system can be a homogeneous, liquid-phase catalyst system capable of promoting at least partial oxidation of the oxidizable compound.
  • the catalyst system can comprise at least one multivalent transition metal.
  • the catalyst system can comprise cobalt, bromine, and/or manganese.
  • the fluid-phase feed stream can comprise cobalt in an amount such that the concentration of cobalt in the liquid phase of the reaction medium is maintained in the range of from about 300 to about 6,000 parts per million by weight (ppmw), in the range of from about 700 to about 4,200 ppmw, or in the range of from 1 ,200 to 3,000 ppmw.
  • ppmw parts per million by weight
  • the fluid-phase feed stream can comprise bromine in an amount such that the concentration of bromine in the liquid phase of the reaction medium is maintained in the range of from about 300 to about 5,000 ppmw, in the range of from about 600 to about 4,000 ppmw, or in the range of from 900 to 3,000 ppmw.
  • the fluid-phase feed stream can comprise manganese in an amount such that the concentration of manganese in the liquid phase of the reaction medium is maintained in the range of from about 20 to about 1,000 ppmw, in the range of from about 40 to about 500 ppmw, or in the range of from 50 to 200 ppmw.
  • cobalt and bromine can both be present in the catalyst system.
  • the weight ratio of cobalt to bromine (Co:Br) in the catalyst system can be in the range of from about 0.25:1 to about 4:1, in the range of from about 0.5:1 to about 3:1, or in the range of from 0.75:1 to 2:1.
  • cobalt and manganese can both be present in the catalyst system.
  • the weight ratio of cobalt to manganese (Co:Mn) in the catalyst system can be in the range of from about 0.3:1 to about 40:1, in the range of from about 5 : 1 to about 30: 1 , or in the range of from 10:1 to 25 : 1.
  • the oxidizable compound e.g., para-xylene
  • the oxidizable compound can be continuously introduced into oxidation zone 10 at a rate of at least about 5,000 kilograms per hour, at a rate in the range of from about 10,000 to about 80,000 kilograms per hour, or in the range of from 20,000 to 50,000 kilograms per hour.
  • the ratio of the mass flow rate of the solvent to the mass flow rate of the oxidizable compound entering oxidation zone 10 can be maintained in the range of from about 2:1 to about 50:1, in the range of from about 5:1 to about 40:1, or in the range of from 7.5:1 to 25:1.
  • the predominately gas-phase oxidant stream introduced into oxidation zone 10 can comprise in the range of from about 5 to about 40 mole percent molecular oxygen, in the range of from about 15 to about 30 mole percent molecular oxygen, or in the range of from 18 to 24 mole percent molecular oxygen.
  • the balance of the oxidant stream can be comprised primarily of a gas or gases, such as nitrogen, that are inert to oxidation.
  • the oxidant stream consists essentially of molecular oxygen and nitrogen.
  • the oxidant stream can be dry air that comprises about 21 mole percent molecular oxygen and about 78 to about 81 mole percent nitrogen.
  • the oxidant stream can comprise substantially pure oxygen.
  • the oxidant stream can be introduced into oxidation zone 10 in an amount that provides molecular, oxygen somewhat exceeding the stoichiometric oxygen demand.
  • the ratio of the mass flow rate of the oxidant stream (e.g., air) to the mass flow rate of the oxidizable compound (e.g., para-xylene) entering oxidation zone 10 can be maintained in the range of from about 0.5:1 to about 20:1 , in the range of from about 1 :1 to about 10:1, or in the range of from 2: 1 to 6:1.
  • the liquid-phase oxidation reaction carried out in oxidation zone 10 can be a precipitating reaction that generates solids.
  • the liquid- phase oxidation carried out in oxidation zone 10 can cause at least about 10 weight percent of the oxidizable compound (e.g., para-xylene) introduced into oxidation zone. 10 to form solids (e.g., crude terephthalic acid (CTA) particles) in the reaction medium.
  • the liquid-phase oxidation carried out in oxidation zone 10 can cause at least about 50 weight percent of the oxidizable compound (e.g., para-xylene) introduced into oxidation zone 10 to form solids (e.g., CTA particles) in the reaction medium.
  • the liquid-phase oxidation carried out in oxidation zone 10 can cause at least about 90 weight percent of the oxidizable compound (e.g., para- xylene) introduced into oxidation zone 10 to form solids (e.g., CTA particles) in the reaction medium.
  • the solids content of the reaction medium can be maintained in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent.
  • solids content shall denote the weight percent solids in a multi-phase mixture.
  • the multi-phase reaction medium can be maintained at an elevated temperature in the range of from about 125 to about 200 0 C 5 in the range of from about 150 to about 18O 0 C, or in the range of from 155 to 165°C.
  • the overhead pressure in oxidation zone 10 can be maintained in the range of from about 1 to about 20 bar gauge (barg), in the range of from about 2 to about 12 barg, or in the range of from 4 to 8 barg.
  • a crude slurry can be withdrawn from an outlet of oxidation zone 10 via line 12.
  • the solid phase of the crude slurry in line 12 can be formed primarily of solid particles of CTA.
  • the liquid phase of the crude slurry in line 12 can be a liquid mother liquor comprising at least a portion of the solvent, one or more catalyst components, and minor amounts of dissolved terephthalic acid (TPA).
  • TPA dissolved terephthalic acid
  • the solids content of the crude slurry in line 12 can be the same as the solids content of the reaction medium in oxidation zone 10, discussed above.
  • the crude slurry in line 12 can comprise impurities.
  • impurities is defined as any substance other than TPA, solvent, catalyst, and water.
  • impurities can include oxidation byproducts formed during the at least partial oxidation of the above-mentioned oxidizable compound (e.g., para-xylene) including, but not limited to, benzoic acid (BA), bromo-benzoic acid, bromo-acetic acid, isophthalic acid, trimellitic acid, 2,5 s 4'-tricarboxybiphenyl, 2,5,4'- tricarboxybenzophenone, para-toluic acid (p-TAc), 4-carboxybenzaldehyde (4- CBA), monocarboxyfiuorenones, monocarboxyfluorenes, and/or dicarboxyfluorenones.
  • benzoic acid BA
  • bromo-benzoic acid bromo-acetic acid
  • isophthalic acid trimellitic
  • the crude slurry can optionally be introduced into purification zone 14 via line 12.
  • the crude slurry can be treated in purification zone 14 such that the concentration of at least one of the above-mentioned impurities in the crude slurry is reduced, thereby producing a purified slurry.
  • Such reduction in the concentration of impurities in the TPA can be accomplished by oxidative digestion, hydrogenation, and/or dissolution/recrystallization.
  • the crude slurry fed to purification zone 14 can have a 4-CBA content of at least about 100 parts per million based on the weight of the solids in the crude slurry (ppmw cs ), in the range of from about 200 to about 10,000 ppmw CS) or in the range of from 800 to 5,000 ppmw cs .
  • the crude slurry fed to purification zone 14 can have a p-TAc content of at least about 250 ppmw cs , in the range of from about 300 to about 5,000 ppmw c s, or in the range of from 400 to 1,500 ppmw cs .
  • the purified slurry exiting purification zone 14 can have a 4-CBA content of less than about 150 parts per million based on the weight of the solids in the purified slurry (ppmwps), less than about 100 ppmw ps , or less than 50 ppmw ps .
  • the purified slurry exiting purification zone 14 can have a p-TAc content of less than about 300 ppmw ps , less than about 200 ppmw ps , or less than 150 ppmw ps .
  • treatment of the crude slurry in purification zone 14 can cause the purified slurry exiting purification zone 14 to have a 4-CBA and/or p-TAc content that is at least about 50 percent less than the 4-CBA and/or p-TAc content of the crude slurry fed to purification zone 14, at least about 85 percent less, or at least 95 percent less.
  • the 4-CBA content of the crude slurry fed to purification zone 14 is 200 ppmw cs and the 4-CBA content of the purified slurry exiting purification zone 14 is 100 ppmw ps
  • the 4-CBA content of the purified slurry is 50 percent less than the 4-CBA content of the crude slurry.
  • the crude slurry can be subjected to purification by oxidative digestion in purification zone 14.
  • oxidative digestion denotes a process step or steps where a feed comprising solid particles is subjected to oxidation under conditions sufficient to permit oxidation of at least a portion of the impurities originally trapped in the solid particles.
  • Purification zone 14 can comprise one or more reactors or zones. In one embodiment, purification zone 14 can comprise one or more mechanically-agitated reactors.
  • a secondary oxidant stream which can have the same composition as the gas-phase oxidant stream fed to oxidation zone 10 discussed above, can be introduced into purification zone 14 to provide the molecular oxygen required for oxidative digestion. Additional oxidation catalyst can be added if necessary.
  • a stream comprising hydrogen can be introduced into purification zone 14 for hydrogenation of the crude slurry.
  • the temperature at which oxidative digestion is carried out can be at least about 10 0 C greater than the temperature of oxidation in oxidation zone 10, in the range of from about 20 to about 80 0 C greater, or in the range of from 30 to 50 0 C greater.
  • the additional heat required for the operation of purification zone 14 can be provided by supplying a vaporized solvent to purification zone 14 and allowing the vaporized solvent to condense therein.
  • the oxidative digestion temperature in purification zone 14 can be maintained in the range of from about 180 to about 240 0 C 5 in the range of from about 190 to about 220 0 C, or in the range of from 200 to 210 0 C.
  • the oxidative digestion pressure in purification zone 14 can be maintained in the range of from about 100 to about 350 pounds per square inch gauge (psig), in the range of from about 175 to about 275 psig, or in the range of from 185 to 225 psig.
  • purification zone 14 can include two digestion reactors/zones - an initial digester and a final digester.
  • the final digester can be operated at a lower temperature and pressure than the initial digester.
  • the operating temperature of the final digester can be at least about 2°C lower than the operating temperature of the initial digester, or in the range of from about 5 to about 15°C lower than the operating temperature of the initial digester.
  • the operating pressure of the final digester can be • at least about 5 psig lower than the operating pressure of the initial digester, or in the range of from about 10 to about 50 psig lower than the operating pressure of the initial digester.
  • the operating temperature of the initial digester can be in the range of from about 195 to about 225°C, in the range of from 205 to 215°C, or about 210 0 C.
  • the operating pressure of the initial digester can be in the range of from about 215 to about 235 psig, or about 225 psig.
  • the operating temperature of the final digester can be in the range of from about 190 to about 220 0 C, in the range of from 200 to 210 0 C, or about 205 0 C.
  • the operating pressure of the final digester can be in the range of from about 190 to 210 psig, or about 200 psig.
  • purification zone 14 can comprise optional first and second solvent swap zones.
  • Optional first and second solvent swap zones can operate to replace at least a portion of the existing solvent in a slurry with a replacement solvent.
  • Equipment suitable for such replacement includes, but is not limited to, a decanter centrifuge followed by a reslurry with replacement solvent, a disc stack centrifuge, an advancing front crystallizer, or multiple decanter centrifuges with optional counter current washing.
  • the replacement oxidation solvent can have substantially the same composition as the solvent introduced into oxidation zone 10, as described above.
  • the crude slurry fed to purification zone 14 can be treated in the optional first solvent swap zone prior to purification of the crude slurry by the above-mentioned oxidative digestion.
  • a purified slurry resulting from oxidative digestion of the crude slurry can be treated in the optional second solvent swap zone.
  • At least a portion of the displaced oxidation solvent from the optional first and/or second solvent swap zones can be discharged from purification zone 14.
  • at least a portion of the displaced oxidation solvent can be routed to oxidation zone 10.
  • purification zone 14 can comprise an optional crystallization zone and/or an optional cooling zone.
  • a purified slurry resulting from the above-mentioned oxidative digestion of the crude slurry can be treated in the optional crystallization zone to at least partially increase the particle size distribution of the purified slurry.
  • Optional crystallization zone can comprise any equipment known in the art that can operate to increase the particle size distribution of the purified slurry.
  • the purified slurry can be cooled therein to a temperature in the range of from about 20 to about 195°C.
  • the purified slurry can be treated first in the crystallization zone and subsequently in the cooling zone.
  • a purified slurry can be withdrawn from an outlet of purification zone 14 via line 16.
  • the solid phase of the purified slurry can be formed primarily of purified terephthalic acid (PTA) particles, while the liquid phase can be formed of a mother liquor.
  • the solids content of the purified slurry in line 16 can be in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent.
  • the purified slurry in line 16 can be introduced into product isolation zone 18 for at least partial recovery of the solid PTA particles.
  • at least a portion of the crude slurry in line 12 can be introduced into product isolation zone 18 via line 12a.
  • the solid phase of the crude shiny can be formed primarily of CTA particles, while the liquid phase can be formed of a mother liquor.
  • the solids content of the crude slurry in line 12a can be in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent.
  • the crude slurry in line 12a can be introduced into product isolation zone 18 for recovery of the solid CTA particles.
  • Product isolation zone 18 can separate the crude slurry and/or the purified slurry into a predominately fluid phase mother liquor and a wet cake.
  • Product isolation zone 18 can comprise any method of solid/liquid separation known in the art that is capable of generating a wet cake and a mother liquor stream.
  • Suitable equipment for use in product isolation zone 18 includes, but is not limited to, a pressure drum filter, a vacuum filter, a vacuum drum filter, a vacuum belt filter, multiple solid bowl centrifuges with optional counter current wash, or a perforated centrifuge.
  • a wash stream can be introduced into product isolation zone 18 to wash at least a portion of the wet cake generated in product isolation zone 18, thereby producing a washed wet cake.
  • the wash stream can comprise acetic acid and/or water.
  • the used wash liquor can be withdrawn from product isolation zone 18, and at least a portion of the wash liquor can be routed, either directly or indirectly, to oxidation zone 10.
  • the above-mentioned wet cake generated in product isolation zone 18 can be discharged via line 20.
  • the wet cake generated in product isolation zone 18 can primarily comprise solid particles of carboxylic acid.
  • the carboxylic acid can be an aromatic dicarboxylic acid, which can be solid TPA particles.
  • the solid TPA particles can comprise CTA and/or PTA particles.
  • the solid particles can have a mean particle size in the range of from about 1 to about 500 ⁇ m, in the range of from about 10 to about 350 ⁇ m, or in the range of from 20 to 200 ⁇ m.
  • the wet cake can comprise in the range of from about 2 to about 25 weight percent liquid, in the range of from about 4 to about 20 weight percent liquid, or in the range of from 6 to 15 weight percent liquid.
  • the wet cake in line 20 can comprise oxidation byproducts, as discussed above.
  • the wet cake in line 20 can comprise acetic acid and/or water.
  • the wet cake in line 20 can be introduced into drying zone 100 via line 20.
  • the wet cake in line 20 can be fed to drying zone 100 at a rate of at least about 20 pounds per hour per square foot (lbs/hr/ft 2 ) of the inner surface area of drying zone 100.
  • the wet cake in line 20 can be fed to drying zone 100 at a feed rate of at least about 35 lbs/hr/ft 2 , or in the range of from about 40 to about 175 lbs/hr/ft 2 .
  • the wet cake in line 20 can have an inlet temperature in the range of from about 0 to about 220°C, in the range of from about 20 to about 200 0 C, in the range of from about 40 to about 150 0 C, in the range of from about 60 to about 120 0 C, or in the range of from 65 to 105 0 C upon entering drying zone 100.
  • the term "inlet temperature” is defined as the temperature of the wet cake immediately upon being introduced into drying zone 100.
  • Drying zone 100 can operate to produce a substantially dry TPA particulate product comprising solid TPA particles.
  • substantially dry is defined as a product comprising less than about 2 weight percent liquid.
  • the substantially dry TPA particulate product can comprise less than about 1 weight percent liquid, less than about 0.5 weight percent liquid, less than about 0.2 weight percent liquid, or less than 0.1 weight percent liquid.
  • At least a portion of the vapor produced from the liquid removed from the solid TPA particles can be removed from drying zone 100 via line 22.
  • the vapor in line 22 can comprise solvent as described above in relation to the solvent contained in the fluid-phase feed stream fed ' to oxidation zone 10 (e.g., acetic acid and/or water).
  • vacuum source 24 can be used to create vacuum conditions in drying zone 100.
  • drying zone 100 can be operated at a pressure in the range of from about 50 to about 750 torr, in the range of from about 100 to about 700 torr, or in the range of from 150 to 650 torr.
  • vacuum source 24 can also operate to create vacuum conditions in product isolation zone 18, such that product isolation zone 18 and drying zone 100 share vacuum source 24.
  • a condenser (not depicted) can be disposed substantially between drying zone 100 and vacuum source 24. The condenser can operate to condense at least a portion of the vapor in line 22.
  • the solid particles can have an average residence time in drying zone 100 of less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 2 minutes, or less than 1 minute.
  • the term "residence time” is defined as the difference in time between the introduction of a solid particle into drying zone 100 via line 20 and the time when that same solid particle exits the drying zone via line 26.
  • the solid particles have a measurable exit temperature upon being withdrawn from drying zone 100 via line 26.
  • the solid particles can have an exit temperature of less than about 250 0 C, in the range of form about 105 to about 240 0 C, in the range of from about 110 to about 200 0 C, in the range of from about 1 15 to about 175°C, or in the range of from 120 to 160 0 C.
  • exit temperature is defined as the temperature of the solid particles immediately upon exiting drying zone 100 (e.g., upon introduction into line 26).
  • the exit temperature of the solid particles can be at least about 25°C greater, at least about 50 0 C greater, or at least 100 0 C greater than the inlet temperature of the wet cake as discussed above.
  • the solid particles exiting drying zone 100 via line 26 can pass through vacuum seal 28.
  • Vacuum seal 28 can operate to allow solid particles to be withdrawn from drying zone 100 while at least partially maintaining the pressure in drying zone 100.
  • vacuum seal 28 can maintain the pressure in drying zone 100 such that, upon withdrawal of solid particles, the pressure change in drying zone 100 is less than about 20 percent, less than about 10 percent, or less than 5 percent.
  • Vacuum seal 28 can be any vacuum seal device that can at least partially maintain the pressure in drying zone 100 while allowing the withdrawal of solids.
  • An example of a suitable device that can be used for vacuum seal 28 includes, but is not limited to, a rotary air lock valve.
  • drying zone 100 can comprise an inert atmosphere during drying operations.
  • inert atmosphere is defined as an atmosphere that is substantially non- reactive in the processes of the present invention.
  • Such an inert atmosphere can be achieved by introducing an inert gas into drying zone 100. Any method known in the art for introducing a gas into a vessel can be employed to introduce the inert gas into drying zone 100.
  • introduction of the inert gas can be achieved by allowing the gas to leak through vacuum seal 28 into line 26, and subsequently into drying zone 100.
  • the inert gas can be directly supplied to drying zone 100 through an inert gas inlet (not depicted).
  • the inert gas can be fed to drying zone 100 at a feed rate of less than about 5 standard cubic feet of gas per pound of wet cake in drying zone 100 (SCF/lb), less than about 3 SCF/lb, or less than 1 SCF/lb.
  • Suitable examples of inert gases useful in the present invention include, but are not limited to, nitrogen and/or air.
  • drying zone 100 can be defined within a dryer. In another embodiment, drying zone 100 can be defined within a contact dryer.
  • contact dryer is defined as a dryer where heat is transferred to the material being dried (e.g., solid TPA particles) by physically contacting the material being dried with a thermally conductive wall (e.g., a heated inner wall) that separates a heat source (e.g., a heat transfer medium) from the material being dried.
  • a thermally conductive wall e.g., a heated inner wall
  • drying zone 100 can be defined within a plurality of contact dryers arranged in series.
  • FIG. 2 illustrates one embodiment of a contact dryer 102 that can define drying zone 100.
  • dryer 102 can comprise a substantially horizontally disposed elongated tubular cylinder 104 presenting an inner surface 106.
  • dryer 102 can comprise a jacket 108 which allows a heat transfer medium to circulate therethrough.
  • dryer 102 can comprise feed inlet 1 10, product outlet 112, and vapor outlet 118.
  • a drying gas inlet 120 can also be provided.
  • cylinder 104 can have a length of less than about 80 feet, less than about 40 feet, or less than 20 feet. Additionally, cylinder 104 can have an inner diameter in the range of from about 1 to about 15 feet. Inner surface 106 can have an area in the range of from about 4 to about 40 square feet (ft 2 ), in the range of from about 6 to about 35 ft 2 , or in the range of from 8 to 30 ft 2 . In one embodiment of the present invention, jacket 108 can substantially envelop cylinder 104, thereby allowing a heat transfer medium to circulate between the outer surface of cylinder 104 and the inner surface of jacket 108.
  • the heat transfer medium circulating in jacket 108 can operate to transfer heat to cylinder 104. This transfer of heat can raise the temperature of inner surface 106, resulting in a heated inner surface.
  • inner surface 106 can have a temperature of at least about 100 0 C, in the range of from about 115 to about 265°C, or in the range of from 200 to 250°C.
  • jacket 108 can have a temperature in the range of from about 120 to about 280 0 C, in the range of from about 160 to about 250 0 C, or in the range of from 200 to 240 0 C.
  • Jacket 108 can comprise heat transfer medium inlet 114 and heat transfer medium outlet 116.
  • Heat transfer medium inlet 114 allows for the introduction of the heat transfer medium into jacket 108, and spent heat transfer medium can be withdrawn via heat transfer medium outlet 116.
  • the heat transfer medium employed in the present invention can be any medium sufficient to increase the temperature of inner surface 106 as discussed above.
  • the heat transfer medium can be a liquid and/or a gas.
  • Suitable examples of heat transfer mediums useful in the present invention include, but are not limited to, steam, water, oil, and/or commercially available natural or synthetic heat transfer medium fluids.
  • the heat transfer medium introduced into jacket 108 can have an inlet temperature in the range of from about 120 to about 280 0 C, in the range of from about 160 to about 250 0 C, or in the range of from 200 to 240 0 C.
  • the term "inlet temperature" is defined as being the temperature of the heat transfer medium immediately upon being introduced into jacket 108.
  • the heat transfer medium can have an outlet temperature in the range of from about 110 to about 270 0 C, in the range of from about 130 to about 250 0 C 5 or in the range of from 150 to 240 0 C.
  • the pressure in jacket 108 during drying operations can be maintained in the range of from about 50 to about 700 pounds per square inch gauge (psig), in the range of from about 70 to about 650 psig, or in the range of from 90 to 600 psig.
  • dryer 102 can comprise a paddle rotor 122.
  • Paddle rotor 122 can be disposed substantially coaxially within cylinder 104.
  • Paddle rotor 122 can comprise a plurality of radial arms 124.
  • Radial arms 124 can be positioned along the length of paddle rotor 122 in a substantially helical pattern.
  • Each of radial arms 124 can comprise a paddle or blade 126 rotatably attached to the end of radial arms 124.
  • Paddles 126 can be adjustably secured to the end of radial arms 124 so as to permit presetting of the pitch of each paddle 126.
  • FIG. 3 illustrates in detail radial arms 124 and paddles 126.
  • the length of radial arms 124 combined with paddles 126 can extend at least about 80 percent, at least about 85 percent, or at least 90 percent of the distance of the annular space created between paddle rotor 122's outer surface 128 and inner surface 106.
  • Paddle rotor 122 can be operable to facilitate contact of the solid particles with inner surface 106 and to facilitate movement of the solid particles through cylinder 104. To achieve such contacting and movement, paddle rotor 122 can rotate so as to impart centrifugal and axially forward forces on at least a portion of the solid particles. In one embodiment, the centrifugal force created by paddle rotor 122 can be sufficient to at least partially overcome the force of gravity, thereby forming a thin layer of the solid particles over at least a portion of inner surface 106.
  • At least about 10 percent, at least about 40 percent, or at least 70 percent of the solid particles introduced into dryer 102 can form a thin layer over at least a portion of inner surface 106.
  • the centrifugal force created by paddle rotor 122 can be sufficient to form a thin layer of solid particles over at least about 20 percent, at least about 35 percent, or at least 50 percent of inner surface 106.
  • the thin layer of solid particles created on inner surface 106 can have an average thickness of less than about 1.5 inches, less than about 1 inch, or less than 0.5 inches.
  • the axially forward forces created by paddle rotor 122 can be sufficient to transport the solid particles from feed inlet 110 to product outlet 112 within the residence times discussed above.
  • Arms 124 and paddles 126 can be oriented so that when paddle rotor 122 rotates, the solid particles follow a substantially helical path from feed inlet 110, along inner surface 106, to product outlet 112.
  • path 130 One example of a substantially helical path the solid particles could follow during drying operations is depicted by path 130.
  • paddle rotor 122 can rotate at a sufficient speed.
  • the speed of rotation of paddle rotor 122 can be measured by determining the speed at which the tips of paddles 126 are traveling (tip speed) during drying operations.
  • the tip speed of paddles 126 during drying operations can be at least about 10 cm/s, in the range of from about 20 to about 400 cm/s, in the range of from about 50 to about 300 cm/s, or in the range of from 100 to 150 cm/s.
  • Vapor discharged from vapor outlet 118 can be treated in substantially the same manner as the vapor in line 22 of FIG. 1, discussed above.
  • Vapor outlet 118 can have a diameter that is sufficiently narrow so as to at least partially prevent entrained solids from escaping dryer 102 concurrent with removed vapor.
  • vapor outlet 118 can have a diameter of less than about 15 feet, less than about 10 feet, or less than 5 feet.
  • a drying gas may be employed to facilitate at least partial direct-contact drying of the solid particles in dryer 102.
  • the drying gas can enter dryer 102 via drying gas inlet 120.
  • the drying gas employed in the present invention can be any gas capable of removing at least a portion of the liquid from the above-mentioned wet cake.
  • Suitable examples of drying gases useful in the present invention include, but are not limited to, nitrogen, TPA process off- gases, oxygen-depleted gas, carbon dioxide, carbon monoxide, and/or air.
  • TPA process off-gas is defined as a gas which was used in the oxidation step of a TPA production process.
  • the TPA process off-gas can be scrubbed and/or treated in a regenerative thermal oxidation unit prior to being employed as a drying gas.
  • oxygen- depleted gas is defined as a gas having less than about 7 mol percent oxygen.
  • the oxygen-depleted gas can have an oxygen content of less than about 5 mol percent, less than about 3 mol percent, or less than 1 mol percent.
  • the drying gas can have an inlet temperature of at least about the boiling point of the liquid to be removed from the wet cake. In another embodiment, the drying gas can have an inlet temperature in the range of from about 100 to about 250 0 C, in the range of from about 120 to about 225°C, or in the range of from 140 to 200 0 C. As used herein, when referring to the drying gas, the term "inlet temperature" is defined as being the temperature of the drying gas immediately upon being introduced into dryer 102. When a drying gas is employed in dryer 102, the pressure in dryer 102 can be up to about 1000 torr during drying operations. The pressure in dryer 102 is determined by measuring the pressure at product outlet 112.
  • the solid particles can exit dryer 102 via product outlet 112.
  • the above-mentioned substantially dry TPA particulate product can comprise at least a portion of the solid particles exiting dryer 102 via product outlet 112.
  • the solid particles exiting dryer 102 via product outlet 112 can be treated in substantially the same manner as the solid particles in line 26 of FIG. 1, discussed above.
  • dryer 102 can be a thin layer contact dryer.
  • the term "thin layer contact dryer” is defined as a contact dryer wherein at least a portion of the solid particles entering the dryer form a layer having an average thickness of less than about 1.5 inches over at least a portion of the heated inner surface of the dryer.
  • Suitable examples of commercially available thin layer contact dryers for use in the present invention include, but are not limited to, a SOLIDAIRE dryer (manufactured by Bepex International LLC, Minneapolis, Minnesota, USA), or a TURBODRYER (manufactured by VOMM S.P.A., Milan, Italy).
  • Non-continuous operations include, but are not limited to, batch-wise operations, cyclical operations, and/or intermittent operations.
  • the first class of dryer used in the examples below was represented by the TORUSDISC TD 12-4 dryer (manufactured by Bepex International LLC, Minneapolis, Minnesota, USA).
  • the TORUSDISC TD 12-4 dryer is an indirect heat exchanger having a heated dryer area of 27.6 square feet.
  • the TORUSDISC TD 12-4 represents a class of dryers characterized by a single or twin shaft heated rotor, a heated jacket, and slow, gentle movement of solids through the dryer during drying.
  • dryers in this class include the DISCOTHERM-B dryer (manufactured by LIST USA Inc., Charlotte, NC, USA), the HOLO-FLITE dryer (manufactured by Metso Minerals, Helsinki, Finland), the PORCUPINE processor (manufactured by Bethlehem Corp., Easton, PA, USA), the K-S NARA PADDLE dryer (manufactured by Komiine-Sanderson Engineering Corp., Peapack, NJ, USA), and the ROVACTOR dryer (manufactured by Buss-SMS- Canzler GmbH, Butzbach, Germany).
  • DISCOTHERM-B dryer manufactured by LIST USA Inc., Charlotte, NC, USA
  • HOLO-FLITE dryer manufactured by Metso Minerals, Helsinki, Finland
  • PORCUPINE processor manufactured by Bethlehem Corp., Easton, PA, USA
  • K-S NARA PADDLE dryer manufactured by Komiine-Sanderson Engineering Corp., Peapack, NJ, USA
  • ROVACTOR dryer
  • the second class of dryer used in the examples below was represented by the SOLIDAIRE dryer (manufactured by Bepex International LLC 5 Minneapolis, Minnesota, USA). Two different models of the SOLIDAIRE dryer were used in the examples below: the SOLIDAIRE SJS 10-6 and the SOLIDAIRE SJS 8-4.
  • the SOLIDAIRE dryers represent a class of dryers known as thin layer contact dryers, which are characterized by a heated jacket, a heated inner surface, and a paddle rotor having blades that can be angled, shaped, or oriented so as to impart centrifugal and axially forward forces to the material being dried.
  • the SOLIDAIRE dryers are capable of producing a highly agitated thin layer of cake.
  • Each of the SOLIDAIRE dryers employed can be direct and/or indirect heat exchangers.
  • the SJS 10-6 dryer has a heated drying area of 15 square feet
  • the SJS 8-4 has a heated drying area of 8 square feet.
  • Another dryer in this class is the TURBODRYER (manufactured by VOMM S.P.A., Milan, Italy).
  • EXAMPLE 3 Dryer Residence Time
  • Example 2 To compare the performance of the dryers described in Example 2, a total of 4 samples of the PTA wet cake containing 18 weight percent moisture, as prepared in Example 1, were dried in a TORUSDISC TD 12-4 dryer and a SOLIDAIRE SJS 10-6 dryer, two samples in each dryer. In each of the 4 runs, the wet cake was metered into the dryer with a screw feeder. The feed rate was varied from 27 pounds per hour per square foot of heated drying area (lbs/hr/ft 2 ) to 93 lbs/hr/ft 2 . A vacuum system was employed during the drying procedure which removed the acid vapor from the dryer. Additionally, during the drying procedure the dryer was purged with nitrogen.
  • the dried PTA was removed from the dryers via a rotary air lock valve, which allowed the dry powder to be removed from the dryer while maintaining a substantially constant level of pressure in the dryer.
  • the dry PTA temperature, the moisture content, and the residence time of the dried PTA product were then measured.
  • the jacket temperature of the dryer was maintained at 180 0 C during drying. The results are listed in Table 1 , below.
  • the effect of the jacket temperature and feed rate on dry PTA temperature, dry PTA weight percent moisture, and dryer residence time was determined by performing drying operations on five samples of the PTA wet cake containing 11 weight percent moisture, as prepared in Example 1. For this determination, a SOLIDAIRE SJS 8-4 dryer was employed. Each sample in turn was metered to the dryer using a screw feeder. The feed rate for each of the five runs was varied from 75 lbs/hr/ft 2 to 175 Ibs/hr/ft 2 . Additionally, the jacket temperature of the dryer was varied from 200°C (Runs 1-3) to 223°C (Run 4) and 244°C (Run 5).
  • the dried PTA was removed from the dryer via a rotary air lock valve, which allowed the dry powder to be removed from the dryer while maintaining a substantially constant level of pressure in the dryer.
  • the dry PTA temperature, the moisture content, and the residence time of the dried PTA product were then measured. The results are listed in Table 2, below.
  • EXAMPLE 5 Thermal Stability of Terephthalic Acid
  • TPA thermal gravimetric analysis
  • CTA crude terephthalic acid
  • PTA thermal gravimetric analysis
  • CTA crude terephthalic acid
  • PTA thermal gravimetric analysis
  • CTA crude terephthalic acid
  • PTA thermal gravimetric analysis
  • One of the PTA samples and one of the CTA samples was tested in an air environment, while the other two samples were tested in a nitrogen environment.
  • ASTM method El 131-03 Standard Test Method for Compositional Analysis by Thermogravimetry
  • the method was modified by lowering the highest testing temperature to 350 0 C.
  • the analyses were performed on a HI-RES TGA 2950 THERMOGRAVIMETRIC ANALYZER (manufactured by TA Instruments, New Castle, DE, USA). The scan rate employed in each analysis was 5°C per minute.
  • FIGS. 4 and 4a depict the results from the TGA analysis of TPA.
  • FIG. 4 depicts the thermal degradation and/or sublimation of terephthalic acid over a temperature range starting at 0 0 C and ending at 350 0 C 5
  • FIG. 4a is a magnified view of FIG. 4, depicting the thermal degradation and/or sublimation of TPA over a temperature range from 185°C to 285°C.
  • FIG. 4a it is apparent that severe thermal degradation and/or sublimation of the TPA begins to occur at temperatures greater than about 250°C.
  • Thermal degradation begins to occur at about 25O 0 C whether the sample is CTA or PTA, and occurs in both air environments and nitrogen environments.
  • the present description uses numerical ranges to quantify certain parameters relating to the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claims limitation that only recite the upper value of the range. For example, a disclosed numerical range of 10 to 100 provides literal support for a claim reciting "greater than 10" (with no upper bounds) and a claim reciting "less than 100" (with no lower bounds).
  • the present description uses specific numerical values to quantify certain parameters relating to the invention, where the specific numerical values are not expressly part of a numerical range.
  • each specific numerical value provided herein is to be construed as providing literal support for a broad, intermediate, and narrow range.
  • the broad range associated with each specific numerical value is the numerical value plus and minus 60 percent of the numerical value, rounded to two significant digits.
  • the intermediate range associated with each specific numerical value is the numerical value plus and minus 30 percent of the numerical value, rounded to two significant digits.
  • the narrow range associated with each specific numerical value is the numerical value plus and minus 15 percent of the numerical value, rounded to two significant digits.
  • the broad, intermediate, and narrow ranges for the pressure difference between these two streams would be 25 to 99 psi, 43 to 81 psi, and 53 to 71 psi, respectively.
  • the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.
  • the terms “a,” “an,” “the,” and “said” mean one or more.
  • the term “and/or,” when used in a list of two or more items means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

Abstract

Disclosed is a method and apparatus for drying a wet cake in a carboxylic acid production process. The method comprises employing a contact dryer for drying solid particles of carboxylic acid, where the solid particles can have a residence time of less than about 7 minutes in the dryer and an exit temperature of less than about 250°C upon exiting the dryer.

Description

METHOD AND APPARATUS FOR DRYING CARBOXYLIC ACID
RELATED APPLICATIONS
This application claims the priority benefit of U.S. Provisional Pat. App. Serial Nos. 60/777,906 and 60/777,908, both filed March I5 2006, the entire disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a drying process for use in the production of a carboxylic acid. More specifically, the present invention concerns a method for drying solid particles of terephthalic acid in a drying zone where the residence time of the solid particles in the drying zone is reduced and the exit temperature of the solid particles is less than about 2500C. 2. Description of the Prior Art
In conventional crude terephthalic acid (CTA) production processes, para-xylene undergoes oxidation to form CTA particles. The CTA particles are then typically subjected to isolation and washing. In a conventional purified terephthalic acid (PTA) production process, an additional step is employed where the CTA particles are purified prior to the isolation/washing step. In either a CTA or a PTA production process, the terephthalic acid (TPA) particles exiting the isolation/washing step are typically in the form of a wet cake. In some TPA production processes, the wet cake is then dried in a dryer to thereby produce a substantially dry TPA product. Various methods are known in the art for drying a TPA product. Such methods include the use of a rotary dryer, as well as drying the TPA wet cake by contacting it with a flow of inert gas, which can be achieved in a fluid bed dryer, a ring dryer, or in a solids conveying system. However, conventional methods for drying TPA can cause significant product degradation and/or sublimation, both of which are undesirable. Accordingly, there is a need for methods and/or equipment that can minimize product degradation and/or sublimation when drying a TPA product.
SUMMARY OF THE INVENTION One embodiment of the present invention concerns a method for drying solid particles comprising a carboxylic acid. The method of this embodiment comprises: (a) introducing a wet cake comprising the solid particles into a drying zone; and (b) drying the wet cake in the drying zone to thereby produce a substantially dry product comprising at least a portion of the solid particles, wherein the solid particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the solid particles have an exit temperature of less than about 2500C upon exiting the drying zone.
Another embodiment of the present invention concerns a method for producing a substantially dry crude terephthalic acid (CTA) particulate product. The method of this embodiment comprises: (a) oxidizing an aromatic compound in an oxidation zone to thereby produce a slurry comprising solid CTA particles; (b) treating at least a portion of the slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of the solid CTA particles; and (c) drying at least a portion of the wet cake in a drying zone to thereby produce the substantially dry CTA particulate product, wherein the CTA particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the CTA particles have an exit temperature of less than about 2500C upon exiting the drying zone.
Yet another embodiment of the present invention concerns a method for producing a substantially dry purified terephthalic acid (PTA) particulate product. The method of this embodiment comprises: (a) oxidizing an aromatic compound in an oxidation zone to thereby produce a first slurry comprising solid crude terephthalic acid (CTA) particles; (b) subjecting at least a portion of the CTA particles to purification in a purification zone to thereby produce a second slurry comprising solid PTA particles; (c) treating at least a portion of the second slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of the PTA particles; and (d) drying the wet cake in a drying zone to thereby produce the substantially dry PTA particulate product, wherein the PTA particles have an average residence time of less than about 7 minutes in the drying zone, and wherein the PTA particles have an exit temperature of less than about 2500C upon exiting the drying zone.
Still another embodiment of the present invention concerns a method for drying a wet cake comprising terephthalic acid (TPA). The method of this embodiment comprises: (a) introducing the wet cake into a dryer; and (b) drying the wet cake in the dryer to thereby produce a dry TPA product, wherein the TPA has an average residence time in the dryer of less than about 7 minutes, and wherein the dry TPA product has a temperature in the range of from about 105 to about 240°C upon exiting the dryer.
BRIEF DESCRIPTION OF THE DRAWING FIGURES A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein:
FIG. 1 is a process flow diagram illustrating a system for the production, purification, and drying of carboxylic acid constructed in accordance with the present invention, particularly illustrating a configuration where the crude slurry from the oxidation reactor is subjected to purification, the resulting purified slurry is subjected to product isolation, and the wet cake from the product isolation zone is subjected to drying in a drying zone;
FIG. 2 is a side view of a dryer that may be used in one embodiment of the present invention with certain sections being cut away to more clearly illustrate the operation of the dryer;
FIG. 3 is a sectional view of the dryer taken along line 3-3 in FIG. 2, particularly illustrating a rotor having a plurality of radial arms affixed thereto and paddles attached to each individual radial arm;
FIG. 4 is a weight percent vs. time plot depicting the thermal gravimetric analyses of purified terephthalic acid (PTA) in air, PTA in nitrogen, crude terephthalic acid (CTA) in air, and CTA in nitrogen, determined in accordance with the procedure described in Example 5; and
FIG. 4a is a magnified view of the plot depicted in FIG. 4, particularly illustrating the weight percent range from 95 to 100 and the time range from 185 to 285 of the weight percent vs. time plot depicted in FIG. 4.
DETAILED DESCRIPTION
FIG. 1 illustrates an embodiment of the present invention where carboxylic acid produced in an oxidation reactor and purified in a purification reactor is subjected to product isolation. A portion of the resulting wet cake from the product isolation zone is treated in a drying zone to thereby produce a substantially dry carboxylic acid particulate product. Various embodiments of the drying zone are described in more detail below with reference to FIGS. 2 and 3. In the embodiment illustrated in FIG. I5 a predominately fluid-phase feed stream containing an oxidizable compound (e.g., para-xylene), a solvent (e.g., acetic acid and/or water), and a catalyst system (e.g., cobalt, manganese, and/or bromine) can be introduced into oxidation zone 10. A predominately gas-phase oxidant stream containing molecular oxygen can also be introduced into oxidation zone 10. The fluid- and gas-phase feed streams form a multiphase reaction medium in oxidation zone 10. The oxidizable compound can undergo partial oxidation in a liquid phase of the reaction medium contained in oxidation zone 10.
In one embodiment of the present invention, oxidation zone 10 can comprise an agitated reactor. Agitation of the reaction medium in oxidation zone 10 can be provided by any means known in the art. As used herein, the term "agitation" shall denote work dissipated into the reaction medium causing fluid flow and/or mixing. In one embodiment, oxidation zone 10 can be a mechanically-agitated reactor equipped with means for mechanically agitating the reaction medium. As used herein, the term "mechanical agitation" shall denote agitation of the reaction medium caused by physical movement of a rigid or flexible element(s) against or within the reaction medium. For example, mechanical agitation can be provided by rotation, oscillation, and/or vibration of internal stirrers, paddles, vibrators, or acoustical diaphragms located in the reaction medium. In another embodiment of the present invention, oxidation zone 10 can comprise a bubble column reactor. As used herein, the term "bubble column reactor" shall denote a reactor for facilitating chemical reactions in a multi-phase reaction medium, wherein agitation of the reaction medium is provided primarily by the upward movement of gas bubbles through the reaction medium. As used herein, the terms "majority," "primarily," and "predominately" shall mean more than 50 percent.
The oxidizable compound present in the fluid-phase feed stream introduced into oxidation zone 10 can comprise at least one hydrocarbyl group. Also, the oxidizable compound can comprise an aromatic compound. In one embodiment, the oxidizable compound can comprise an aromatic compound with at least one attached hydrocarbyl group or at least one attached substituted hydrocarbyl group or at least one attached heteroatom or at least one attached carboxylic acid function (-COOH). In another embodiment, the oxidizable compound can comprise an aromatic compound with at least one attached hydrocarbyl group or at least one attached substituted hydrocarbyl group with each attached group comprising from 1 to 5 carbon atoms. In yet another embodiment, the oxidizable compound can be an aromatic compound having exactly two attached groups with each attached group comprising exactly one carbon atom and consisting of methyl groups and/or substituted methyl groups and/or at most one carboxylic acid group. Suitable examples of the oxidizable compound include, but are not limited to, para-xylene, meta-xylene, para- tolualdehyde, meta-tolualdehyde, para-toluic acid, meta-toluic acid, and/or acetaldehyde. In one embodiment of the present invention, the oxidizable compound comprises para-xylene.
A "hydrocarbyl group," as defined herein, is at least one carbon atom that is bonded only to hydrogen atoms and/or to other carbon atoms. A "substituted hydrocarbyl group," as defined herein, is at least one carbon atom bonded to at least one heteroatom and to at least one hydrogen atom. "Heteroatoms," as defined herein, are all atoms other than carbon and hydrogen atoms. "Aromatic compounds," as defined herein, comprise an aromatic ring and can comprise at least 6 carbon atoms and can also comprise only carbon atoms as part of the ring. Suitable examples of such aromatic rings include, but are not limited to, benzene, biphenyl, terphenyl, naphthalene, and other carbon- based fused aromatic rings.
The amount of oxidizable compound present in the fluid-phase feed stream introduced into oxidation zone 10 can be in the range of from about 4 to about 20 weight percent, or in the range of from 6 to 15 weight percent.
The solvent present in the fluid-phase feed stream introduced into primary oxidation reactor 10 can comprise an acid component and a water component. The solvent can be present in the fluid-phase feed stream at a concentration in the range of from about 60 to about 98 weight percent, in the range of from about 80 to about 96 weight percent, or in the range of from 85 to 94 weight percent. The acid component of the solvent can be an organic low molecular weight monocarboxylic acid having from 1 to 6 carbon atoms, or 2 carbon atoms. In one embodiment, the acid component of the solvent can comprise acetic acid. The acid component can make up at least about 75 weight percent of the solvent, at least about 80 weight percent of the solvent, or in the range of from 85 to 98 weight percent of the solvent, with the balance being water.
As mentioned above, the fluid-phase feed stream introduced into oxidation zone 10 can also include a catalyst system. The catalyst system can be a homogeneous, liquid-phase catalyst system capable of promoting at least partial oxidation of the oxidizable compound. Also, the catalyst system can comprise at least one multivalent transition metal. In one embodiment, the catalyst system can comprise cobalt, bromine, and/or manganese.
When cobalt is present in the catalyst system, the fluid-phase feed stream can comprise cobalt in an amount such that the concentration of cobalt in the liquid phase of the reaction medium is maintained in the range of from about 300 to about 6,000 parts per million by weight (ppmw), in the range of from about 700 to about 4,200 ppmw, or in the range of from 1 ,200 to 3,000 ppmw. When bromine is present in the catalyst system, the fluid-phase feed stream can comprise bromine in an amount such that the concentration of bromine in the liquid phase of the reaction medium is maintained in the range of from about 300 to about 5,000 ppmw, in the range of from about 600 to about 4,000 ppmw, or in the range of from 900 to 3,000 ppmw. When manganese is present in the catalyst system, the fluid-phase feed stream can comprise manganese in an amount such that the concentration of manganese in the liquid phase of the reaction medium is maintained in the range of from about 20 to about 1,000 ppmw, in the range of from about 40 to about 500 ppmw, or in the range of from 50 to 200 ppmw.
In one embodiment of the present invention, cobalt and bromine can both be present in the catalyst system. The weight ratio of cobalt to bromine (Co:Br) in the catalyst system can be in the range of from about 0.25:1 to about 4:1, in the range of from about 0.5:1 to about 3:1, or in the range of from 0.75:1 to 2:1. In another embodiment, cobalt and manganese can both be present in the catalyst system. The weight ratio of cobalt to manganese (Co:Mn) in the catalyst system can be in the range of from about 0.3:1 to about 40:1, in the range of from about 5 : 1 to about 30: 1 , or in the range of from 10:1 to 25 : 1.
During oxidation, the oxidizable compound (e.g., para-xylene) can be continuously introduced into oxidation zone 10 at a rate of at least about 5,000 kilograms per hour, at a rate in the range of from about 10,000 to about 80,000 kilograms per hour, or in the range of from 20,000 to 50,000 kilograms per hour. During oxidation, the ratio of the mass flow rate of the solvent to the mass flow rate of the oxidizable compound entering oxidation zone 10 can be maintained in the range of from about 2:1 to about 50:1, in the range of from about 5:1 to about 40:1, or in the range of from 7.5:1 to 25:1.
The predominately gas-phase oxidant stream introduced into oxidation zone 10 can comprise in the range of from about 5 to about 40 mole percent molecular oxygen, in the range of from about 15 to about 30 mole percent molecular oxygen, or in the range of from 18 to 24 mole percent molecular oxygen. The balance of the oxidant stream can be comprised primarily of a gas or gases, such as nitrogen, that are inert to oxidation. In one embodiment, the oxidant stream consists essentially of molecular oxygen and nitrogen. In another embodiment, the oxidant stream can be dry air that comprises about 21 mole percent molecular oxygen and about 78 to about 81 mole percent nitrogen. In an alternative embodiment of the present invention, the oxidant stream can comprise substantially pure oxygen.
During liquid-phase oxidation in oxidation zone 10, the oxidant stream can be introduced into oxidation zone 10 in an amount that provides molecular, oxygen somewhat exceeding the stoichiometric oxygen demand. Thus, the ratio of the mass flow rate of the oxidant stream (e.g., air) to the mass flow rate of the oxidizable compound (e.g., para-xylene) entering oxidation zone 10 can be maintained in the range of from about 0.5:1 to about 20:1 , in the range of from about 1 :1 to about 10:1, or in the range of from 2: 1 to 6:1.
The liquid-phase oxidation reaction carried out in oxidation zone 10 can be a precipitating reaction that generates solids. In one embodiment, the liquid- phase oxidation carried out in oxidation zone 10 can cause at least about 10 weight percent of the oxidizable compound (e.g., para-xylene) introduced into oxidation zone. 10 to form solids (e.g., crude terephthalic acid (CTA) particles) in the reaction medium. In another embodiment, the liquid-phase oxidation carried out in oxidation zone 10 can cause at least about 50 weight percent of the oxidizable compound (e.g., para-xylene) introduced into oxidation zone 10 to form solids (e.g., CTA particles) in the reaction medium. In yet another embodiment, the liquid-phase oxidation carried out in oxidation zone 10 can cause at least about 90 weight percent of the oxidizable compound (e.g., para- xylene) introduced into oxidation zone 10 to form solids (e.g., CTA particles) in the reaction medium. In one embodiment, the solids content of the reaction medium can be maintained in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent. As used herein, the term "solids content" shall denote the weight percent solids in a multi-phase mixture.
During oxidation in oxidation zone 10, the multi-phase reaction medium can be maintained at an elevated temperature in the range of from about 125 to about 2000C5 in the range of from about 150 to about 18O0C, or in the range of from 155 to 165°C. The overhead pressure in oxidation zone 10 can be maintained in the range of from about 1 to about 20 bar gauge (barg), in the range of from about 2 to about 12 barg, or in the range of from 4 to 8 barg.
In the embodiment of FIG. 1 , a crude slurry can be withdrawn from an outlet of oxidation zone 10 via line 12. The solid phase of the crude slurry in line 12 can be formed primarily of solid particles of CTA. The liquid phase of the crude slurry in line 12 can be a liquid mother liquor comprising at least a portion of the solvent, one or more catalyst components, and minor amounts of dissolved terephthalic acid (TPA). The solids content of the crude slurry in line 12 can be the same as the solids content of the reaction medium in oxidation zone 10, discussed above.
In one embodiment of the present invention, the crude slurry in line 12 can comprise impurities. As used herein, the term "impurities" is defined as any substance other than TPA, solvent, catalyst, and water. Such impurities can include oxidation byproducts formed during the at least partial oxidation of the above-mentioned oxidizable compound (e.g., para-xylene) including, but not limited to, benzoic acid (BA), bromo-benzoic acid, bromo-acetic acid, isophthalic acid, trimellitic acid, 2,5s4'-tricarboxybiphenyl, 2,5,4'- tricarboxybenzophenone, para-toluic acid (p-TAc), 4-carboxybenzaldehyde (4- CBA), monocarboxyfiuorenones, monocarboxyfluorenes, and/or dicarboxyfluorenones.
Subsequent to removal from oxidation zone 10, the crude slurry can optionally be introduced into purification zone 14 via line 12. In one embodiment, the crude slurry can be treated in purification zone 14 such that the concentration of at least one of the above-mentioned impurities in the crude slurry is reduced, thereby producing a purified slurry. Such reduction in the concentration of impurities in the TPA can be accomplished by oxidative digestion, hydrogenation, and/or dissolution/recrystallization.
In one embodiment of the present invention, the crude slurry fed to purification zone 14 can have a 4-CBA content of at least about 100 parts per million based on the weight of the solids in the crude slurry (ppmwcs), in the range of from about 200 to about 10,000 ppmwCS) or in the range of from 800 to 5,000 ppmwcs. The crude slurry fed to purification zone 14 can have a p-TAc content of at least about 250 ppmwcs, in the range of from about 300 to about 5,000 ppmwcs, or in the range of from 400 to 1,500 ppmwcs. The purified slurry exiting purification zone 14 can have a 4-CBA content of less than about 150 parts per million based on the weight of the solids in the purified slurry (ppmwps), less than about 100 ppmwps, or less than 50 ppmwps. The purified slurry exiting purification zone 14 can have a p-TAc content of less than about 300 ppmwps, less than about 200 ppmwps, or less than 150 ppmwps. In one embodiment, treatment of the crude slurry in purification zone 14 can cause the purified slurry exiting purification zone 14 to have a 4-CBA and/or p-TAc content that is at least about 50 percent less than the 4-CBA and/or p-TAc content of the crude slurry fed to purification zone 14, at least about 85 percent less, or at least 95 percent less. By way of illustration, if the 4-CBA content of the crude slurry fed to purification zone 14 is 200 ppmwcs and the 4-CBA content of the purified slurry exiting purification zone 14 is 100 ppmwps, then the 4-CBA content of the purified slurry is 50 percent less than the 4-CBA content of the crude slurry.
In one embodiment of the present invention, the crude slurry can be subjected to purification by oxidative digestion in purification zone 14. As used herein, the term "oxidative digestion" denotes a process step or steps where a feed comprising solid particles is subjected to oxidation under conditions sufficient to permit oxidation of at least a portion of the impurities originally trapped in the solid particles. Purification zone 14 can comprise one or more reactors or zones. In one embodiment, purification zone 14 can comprise one or more mechanically-agitated reactors. A secondary oxidant stream, which can have the same composition as the gas-phase oxidant stream fed to oxidation zone 10 discussed above, can be introduced into purification zone 14 to provide the molecular oxygen required for oxidative digestion. Additional oxidation catalyst can be added if necessary. In an alternative embodiment of the present invention, a stream comprising hydrogen can be introduced into purification zone 14 for hydrogenation of the crude slurry.
When oxidative digestion is employed in purification zone 14, the temperature at which oxidative digestion is carried out can be at least about 100C greater than the temperature of oxidation in oxidation zone 10, in the range of from about 20 to about 800C greater, or in the range of from 30 to 500C greater. The additional heat required for the operation of purification zone 14 can be provided by supplying a vaporized solvent to purification zone 14 and allowing the vaporized solvent to condense therein. The oxidative digestion temperature in purification zone 14 can be maintained in the range of from about 180 to about 2400C5 in the range of from about 190 to about 2200C, or in the range of from 200 to 2100C. The oxidative digestion pressure in purification zone 14 can be maintained in the range of from about 100 to about 350 pounds per square inch gauge (psig), in the range of from about 175 to about 275 psig, or in the range of from 185 to 225 psig. In one embodiment of the present invention, purification zone 14 can include two digestion reactors/zones - an initial digester and a final digester. When purification zone 14 includes an initial digester and a final digester, the final digester can be operated at a lower temperature and pressure than the initial digester. In one embodiment, the operating temperature of the final digester can be at least about 2°C lower than the operating temperature of the initial digester, or in the range of from about 5 to about 15°C lower than the operating temperature of the initial digester. In one embodiment, the operating pressure of the final digester can be at least about 5 psig lower than the operating pressure of the initial digester, or in the range of from about 10 to about 50 psig lower than the operating pressure of the initial digester. The operating temperature of the initial digester can be in the range of from about 195 to about 225°C, in the range of from 205 to 215°C, or about 2100C. The operating pressure of the initial digester can be in the range of from about 215 to about 235 psig, or about 225 psig. The operating temperature of the final digester can be in the range of from about 190 to about 2200C, in the range of from 200 to 2100C, or about 2050C. The operating pressure of the final digester can be in the range of from about 190 to 210 psig, or about 200 psig.
In one embodiment of the present invention, purification zone 14 can comprise optional first and second solvent swap zones. Optional first and second solvent swap zones can operate to replace at least a portion of the existing solvent in a slurry with a replacement solvent. Equipment suitable for such replacement includes, but is not limited to, a decanter centrifuge followed by a reslurry with replacement solvent, a disc stack centrifuge, an advancing front crystallizer, or multiple decanter centrifuges with optional counter current washing. The replacement oxidation solvent can have substantially the same composition as the solvent introduced into oxidation zone 10, as described above.
In one embodiment, the crude slurry fed to purification zone 14 can be treated in the optional first solvent swap zone prior to purification of the crude slurry by the above-mentioned oxidative digestion. In another embodiment, a purified slurry resulting from oxidative digestion of the crude slurry can be treated in the optional second solvent swap zone.
Optionally, at least a portion of the displaced oxidation solvent from the optional first and/or second solvent swap zones can be discharged from purification zone 14. In one embodiment, at least a portion of the displaced oxidation solvent can be routed to oxidation zone 10.
In another embodiment of the present invention, purification zone 14 can comprise an optional crystallization zone and/or an optional cooling zone. A purified slurry resulting from the above-mentioned oxidative digestion of the crude slurry can be treated in the optional crystallization zone to at least partially increase the particle size distribution of the purified slurry. Optional crystallization zone can comprise any equipment known in the art that can operate to increase the particle size distribution of the purified slurry. When an optional cooling zone is employed, the purified slurry can be cooled therein to a temperature in the range of from about 20 to about 195°C. When both a crystallization zone and a cooling zone are employed, the purified slurry can be treated first in the crystallization zone and subsequently in the cooling zone.
Referring again to FIG. 1, a purified slurry can be withdrawn from an outlet of purification zone 14 via line 16. The solid phase of the purified slurry can be formed primarily of purified terephthalic acid (PTA) particles, while the liquid phase can be formed of a mother liquor. The solids content of the purified slurry in line 16 can be in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent. The purified slurry in line 16 can be introduced into product isolation zone 18 for at least partial recovery of the solid PTA particles. Optionally, at least a portion of the crude slurry in line 12 can be introduced into product isolation zone 18 via line 12a. As mentioned above, the solid phase of the crude shiny can be formed primarily of CTA particles, while the liquid phase can be formed of a mother liquor. The solids content of the crude slurry in line 12a can be in the range of from about 5 to about 40 weight percent, in the range of from about 10 to about 35 weight percent, or in the range of from 15 to 30 weight percent. The crude slurry in line 12a can be introduced into product isolation zone 18 for recovery of the solid CTA particles.
Product isolation zone 18 can separate the crude slurry and/or the purified slurry into a predominately fluid phase mother liquor and a wet cake. Product isolation zone 18 can comprise any method of solid/liquid separation known in the art that is capable of generating a wet cake and a mother liquor stream. In addition, it may be desirable for product isolation zone 18 to have the capability of washing the wet cake. Suitable equipment for use in product isolation zone 18 includes, but is not limited to, a pressure drum filter, a vacuum filter, a vacuum drum filter, a vacuum belt filter, multiple solid bowl centrifuges with optional counter current wash, or a perforated centrifuge.
In one embodiment of the present invention, a wash stream can be introduced into product isolation zone 18 to wash at least a portion of the wet cake generated in product isolation zone 18, thereby producing a washed wet cake. In one embodiment, the wash stream can comprise acetic acid and/or water. Optionally, after washing the wet cake, the used wash liquor can be withdrawn from product isolation zone 18, and at least a portion of the wash liquor can be routed, either directly or indirectly, to oxidation zone 10. The above-mentioned wet cake generated in product isolation zone 18 can be discharged via line 20. In one embodiment of the present invention, the wet cake generated in product isolation zone 18 can primarily comprise solid particles of carboxylic acid. In one embodiment, the carboxylic acid can be an aromatic dicarboxylic acid, which can be solid TPA particles. The solid TPA particles can comprise CTA and/or PTA particles. In one embodiment, the solid particles can have a mean particle size in the range of from about 1 to about 500 μm, in the range of from about 10 to about 350 μm, or in the range of from 20 to 200 μm.
In one embodiment of the present invention, the wet cake can comprise in the range of from about 2 to about 25 weight percent liquid, in the range of from about 4 to about 20 weight percent liquid, or in the range of from 6 to 15 weight percent liquid. Additionally, the wet cake in line 20 can comprise oxidation byproducts, as discussed above. Furthermore, the wet cake in line 20 can comprise acetic acid and/or water. In one embodiment of the present invention, the wet cake in line 20 can be introduced into drying zone 100 via line 20. The wet cake in line 20 can be fed to drying zone 100 at a rate of at least about 20 pounds per hour per square foot (lbs/hr/ft2) of the inner surface area of drying zone 100. In another embodiment, the wet cake in line 20 can be fed to drying zone 100 at a feed rate of at least about 35 lbs/hr/ft2, or in the range of from about 40 to about 175 lbs/hr/ft2. The wet cake in line 20 can have an inlet temperature in the range of from about 0 to about 220°C, in the range of from about 20 to about 2000C, in the range of from about 40 to about 1500C, in the range of from about 60 to about 1200C, or in the range of from 65 to 1050C upon entering drying zone 100. As used herein, the term "inlet temperature" is defined as the temperature of the wet cake immediately upon being introduced into drying zone 100.
Drying zone 100 can operate to produce a substantially dry TPA particulate product comprising solid TPA particles. As used herein, the term "substantially dry" is defined as a product comprising less than about 2 weight percent liquid. In another embodiment of the present invention, the substantially dry TPA particulate product can comprise less than about 1 weight percent liquid, less than about 0.5 weight percent liquid, less than about 0.2 weight percent liquid, or less than 0.1 weight percent liquid.
In one embodiment, at least a portion of the vapor produced from the liquid removed from the solid TPA particles can be removed from drying zone 100 via line 22. The vapor in line 22 can comprise solvent as described above in relation to the solvent contained in the fluid-phase feed stream fed ' to oxidation zone 10 (e.g., acetic acid and/or water).
Referring still to FIG.. 1, in one embodiment of the present invention, vacuum source 24 can be used to create vacuum conditions in drying zone 100. During drying operations, drying zone 100 can be operated at a pressure in the range of from about 50 to about 750 torr, in the range of from about 100 to about 700 torr, or in the range of from 150 to 650 torr. In another embodiment, vacuum source 24 can also operate to create vacuum conditions in product isolation zone 18, such that product isolation zone 18 and drying zone 100 share vacuum source 24. In another embodiment, a condenser (not depicted) can be disposed substantially between drying zone 100 and vacuum source 24. The condenser can operate to condense at least a portion of the vapor in line 22.
In one embodiment of the present invention, the solid particles can have an average residence time in drying zone 100 of less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 2 minutes, or less than 1 minute. As used herein, the term "residence time" is defined as the difference in time between the introduction of a solid particle into drying zone 100 via line 20 and the time when that same solid particle exits the drying zone via line 26.
In another embodiment of the present invention, the solid particles have a measurable exit temperature upon being withdrawn from drying zone 100 via line 26. In one embodiment, the solid particles can have an exit temperature of less than about 2500C, in the range of form about 105 to about 2400C, in the range of from about 110 to about 2000C, in the range of from about 1 15 to about 175°C, or in the range of from 120 to 1600C. As used herein, the term "exit temperature" is defined as the temperature of the solid particles immediately upon exiting drying zone 100 (e.g., upon introduction into line 26). Additionally, the exit temperature of the solid particles can be at least about 25°C greater, at least about 500C greater, or at least 1000C greater than the inlet temperature of the wet cake as discussed above. In one embodiment of the present invention, the solid particles exiting drying zone 100 via line 26 can pass through vacuum seal 28. Vacuum seal 28 can operate to allow solid particles to be withdrawn from drying zone 100 while at least partially maintaining the pressure in drying zone 100. In one embodiment, vacuum seal 28 can maintain the pressure in drying zone 100 such that, upon withdrawal of solid particles, the pressure change in drying zone 100 is less than about 20 percent, less than about 10 percent, or less than 5 percent. Vacuum seal 28 can be any vacuum seal device that can at least partially maintain the pressure in drying zone 100 while allowing the withdrawal of solids. An example of a suitable device that can be used for vacuum seal 28 includes, but is not limited to, a rotary air lock valve.
In one embodiment of the present invention, drying zone 100 can comprise an inert atmosphere during drying operations. As used herein, the term "inert atmosphere" is defined as an atmosphere that is substantially non- reactive in the processes of the present invention. Such an inert atmosphere can be achieved by introducing an inert gas into drying zone 100. Any method known in the art for introducing a gas into a vessel can be employed to introduce the inert gas into drying zone 100. In one embodiment, introduction of the inert gas can be achieved by allowing the gas to leak through vacuum seal 28 into line 26, and subsequently into drying zone 100. In an alternate embodiment, the inert gas can be directly supplied to drying zone 100 through an inert gas inlet (not depicted). The inert gas can be fed to drying zone 100 at a feed rate of less than about 5 standard cubic feet of gas per pound of wet cake in drying zone 100 (SCF/lb), less than about 3 SCF/lb, or less than 1 SCF/lb. Suitable examples of inert gases useful in the present invention include, but are not limited to, nitrogen and/or air. In one embodiment of the present invention, drying zone 100 can be defined within a dryer. In another embodiment, drying zone 100 can be defined within a contact dryer. As used herein, the term "contact dryer" is defined as a dryer where heat is transferred to the material being dried (e.g., solid TPA particles) by physically contacting the material being dried with a thermally conductive wall (e.g., a heated inner wall) that separates a heat source (e.g., a heat transfer medium) from the material being dried. In an alternate embodiment, drying zone 100 can be defined within a plurality of contact dryers arranged in series.
FIG. 2 illustrates one embodiment of a contact dryer 102 that can define drying zone 100. In this embodiment, dryer 102 can comprise a substantially horizontally disposed elongated tubular cylinder 104 presenting an inner surface 106. Furthermore, dryer 102 can comprise a jacket 108 which allows a heat transfer medium to circulate therethrough. Additionally, dryer 102 can comprise feed inlet 1 10, product outlet 112, and vapor outlet 118. Optionally, a drying gas inlet 120 can also be provided.
In one embodiment of the present invention, cylinder 104 can have a length of less than about 80 feet, less than about 40 feet, or less than 20 feet. Additionally, cylinder 104 can have an inner diameter in the range of from about 1 to about 15 feet. Inner surface 106 can have an area in the range of from about 4 to about 40 square feet (ft2), in the range of from about 6 to about 35 ft2, or in the range of from 8 to 30 ft2. In one embodiment of the present invention, jacket 108 can substantially envelop cylinder 104, thereby allowing a heat transfer medium to circulate between the outer surface of cylinder 104 and the inner surface of jacket 108. During drying operations, the heat transfer medium circulating in jacket 108 can operate to transfer heat to cylinder 104. This transfer of heat can raise the temperature of inner surface 106, resulting in a heated inner surface. During drying operations, inner surface 106 can have a temperature of at least about 1000C, in the range of from about 115 to about 265°C, or in the range of from 200 to 250°C. During drying operations, jacket 108 can have a temperature in the range of from about 120 to about 2800C, in the range of from about 160 to about 2500C, or in the range of from 200 to 2400C.
Jacket 108 can comprise heat transfer medium inlet 114 and heat transfer medium outlet 116. Heat transfer medium inlet 114 allows for the introduction of the heat transfer medium into jacket 108, and spent heat transfer medium can be withdrawn via heat transfer medium outlet 116.
The heat transfer medium employed in the present invention can be any medium sufficient to increase the temperature of inner surface 106 as discussed above. In one embodiment, the heat transfer medium can be a liquid and/or a gas. Suitable examples of heat transfer mediums useful in the present invention include, but are not limited to, steam, water, oil, and/or commercially available natural or synthetic heat transfer medium fluids. The heat transfer medium introduced into jacket 108 can have an inlet temperature in the range of from about 120 to about 2800C, in the range of from about 160 to about 2500C, or in the range of from 200 to 2400C. As used herein, when referring to the heat transfer medium, the term "inlet temperature" is defined as being the temperature of the heat transfer medium immediately upon being introduced into jacket 108. Furthermore, the heat transfer medium can have an outlet temperature in the range of from about 110 to about 2700C, in the range of from about 130 to about 2500C5 or in the range of from 150 to 2400C. Additionally, the pressure in jacket 108 during drying operations can be maintained in the range of from about 50 to about 700 pounds per square inch gauge (psig), in the range of from about 70 to about 650 psig, or in the range of from 90 to 600 psig.
Referring still to FIG. 2, dryer 102 can comprise a paddle rotor 122.
Paddle rotor 122 can be disposed substantially coaxially within cylinder 104. Paddle rotor 122 can comprise a plurality of radial arms 124. Radial arms 124 can be positioned along the length of paddle rotor 122 in a substantially helical pattern. Each of radial arms 124 can comprise a paddle or blade 126 rotatably attached to the end of radial arms 124. Paddles 126 can be adjustably secured to the end of radial arms 124 so as to permit presetting of the pitch of each paddle 126.
FIG. 3 illustrates in detail radial arms 124 and paddles 126. The length of radial arms 124 combined with paddles 126 can extend at least about 80 percent, at least about 85 percent, or at least 90 percent of the distance of the annular space created between paddle rotor 122's outer surface 128 and inner surface 106.
Referring again to FIG. 2, at least a portion of the wet cake comprising the solid particles as discussed above can be introduced into dryer 102 via feed inlet 110. Paddle rotor 122 can be operable to facilitate contact of the solid particles with inner surface 106 and to facilitate movement of the solid particles through cylinder 104. To achieve such contacting and movement, paddle rotor 122 can rotate so as to impart centrifugal and axially forward forces on at least a portion of the solid particles. In one embodiment, the centrifugal force created by paddle rotor 122 can be sufficient to at least partially overcome the force of gravity, thereby forming a thin layer of the solid particles over at least a portion of inner surface 106. In one embodiment, at least about 10 percent, at least about 40 percent, or at least 70 percent of the solid particles introduced into dryer 102 can form a thin layer over at least a portion of inner surface 106. The centrifugal force created by paddle rotor 122 can be sufficient to form a thin layer of solid particles over at least about 20 percent, at least about 35 percent, or at least 50 percent of inner surface 106. The thin layer of solid particles created on inner surface 106 can have an average thickness of less than about 1.5 inches, less than about 1 inch, or less than 0.5 inches.
The axially forward forces created by paddle rotor 122 can be sufficient to transport the solid particles from feed inlet 110 to product outlet 112 within the residence times discussed above. Arms 124 and paddles 126 can be oriented so that when paddle rotor 122 rotates, the solid particles follow a substantially helical path from feed inlet 110, along inner surface 106, to product outlet 112. One example of a substantially helical path the solid particles could follow during drying operations is depicted by path 130. In order to achieve the above-mentioned centrifugal and axially forward forces on the solid particles, paddle rotor 122 can rotate at a sufficient speed. The speed of rotation of paddle rotor 122 can be measured by determining the speed at which the tips of paddles 126 are traveling (tip speed) during drying operations. The tip speed of paddles 126 during drying operations can be at least about 10 cm/s, in the range of from about 20 to about 400 cm/s, in the range of from about 50 to about 300 cm/s, or in the range of from 100 to 150 cm/s.
At least a portion of the liquid removed from the above-mentioned wet cake during drying operations can be discharged via vapor outlet 118. Vapor discharged from vapor outlet 118 can be treated in substantially the same manner as the vapor in line 22 of FIG. 1, discussed above. Vapor outlet 118 can have a diameter that is sufficiently narrow so as to at least partially prevent entrained solids from escaping dryer 102 concurrent with removed vapor. In one embodiment, vapor outlet 118 can have a diameter of less than about 15 feet, less than about 10 feet, or less than 5 feet.
In one embodiment of the present invention, a drying gas may be employed to facilitate at least partial direct-contact drying of the solid particles in dryer 102. When a drying gas is employed, the drying gas can enter dryer 102 via drying gas inlet 120. The drying gas employed in the present invention can be any gas capable of removing at least a portion of the liquid from the above-mentioned wet cake. Suitable examples of drying gases useful in the present invention include, but are not limited to, nitrogen, TPA process off- gases, oxygen-depleted gas, carbon dioxide, carbon monoxide, and/or air. As used herein, the term "TPA process off-gas" is defined as a gas which was used in the oxidation step of a TPA production process. Optionally, the TPA process off-gas can be scrubbed and/or treated in a regenerative thermal oxidation unit prior to being employed as a drying gas. As used herein, the term "oxygen- depleted gas" is defined as a gas having less than about 7 mol percent oxygen. In one embodiment, the oxygen-depleted gas can have an oxygen content of less than about 5 mol percent, less than about 3 mol percent, or less than 1 mol percent.
In one embodiment, the drying gas can have an inlet temperature of at least about the boiling point of the liquid to be removed from the wet cake. In another embodiment, the drying gas can have an inlet temperature in the range of from about 100 to about 2500C, in the range of from about 120 to about 225°C, or in the range of from 140 to 2000C. As used herein, when referring to the drying gas, the term "inlet temperature" is defined as being the temperature of the drying gas immediately upon being introduced into dryer 102. When a drying gas is employed in dryer 102, the pressure in dryer 102 can be up to about 1000 torr during drying operations. The pressure in dryer 102 is determined by measuring the pressure at product outlet 112.
As mentioned above, the solid particles can exit dryer 102 via product outlet 112. In one embodiment of the present invention, the above-mentioned substantially dry TPA particulate product can comprise at least a portion of the solid particles exiting dryer 102 via product outlet 112. In another embodiment, the solid particles exiting dryer 102 via product outlet 112 can be treated in substantially the same manner as the solid particles in line 26 of FIG. 1, discussed above.
In one embodiment of the present invention, dryer 102 can be a thin layer contact dryer. As used herein, the term "thin layer contact dryer" is defined as a contact dryer wherein at least a portion of the solid particles entering the dryer form a layer having an average thickness of less than about 1.5 inches over at least a portion of the heated inner surface of the dryer. Suitable examples of commercially available thin layer contact dryers for use in the present invention include, but are not limited to, a SOLIDAIRE dryer (manufactured by Bepex International LLC, Minneapolis, Minnesota, USA), or a TURBODRYER (manufactured by VOMM S.P.A., Milan, Italy).
It will be understood by one skilled in the art that each of the above- described embodiments, as well as any sub-parts of those embodiments, may be operated in a continuous or a non-continuous manner. Non-continuous operations include, but are not limited to, batch-wise operations, cyclical operations, and/or intermittent operations.
EXAMPLES
The following examples are intended to be illustrative of the present invention in order to teach one of ordinary skill in the art to make and use the invention and are not intended to limit the scope of the invention in any way.
EXAMPLE 1 - Preparation of PTA Wet Cake
Two batches of PTA wet cake were prepared for use in the examples below. Each batch was prepared by mixing glacial acetic acid with dry PTA powder in a 16 cubic foot ribbon mixer. Batch 1 was prepared by first adding approximately 600 lbs of dry PTA powder to the ribbon mixer and turning on the agitator. Next, approximately 67 lbs of glacial acetic acid was added over approximately a 1 hour time period. The mixer was then allowed to operate for several hours to ensure a substantially homogeneous mixture. Bach 2 was prepared in the same manner as batch 1, except approximately 150 lbs of glacial acetic acid was mixed with the 600 lbs of dry PTA powder. After mixing, each batch was analyzed to determine its moisture content. Batch 1 contained 11 weight percent moisture and batch 2 contained 18 weight percent moisture. EXAMPLE 2 - Dryers
Two different classes of dryers were compared in the examples below for their efficacy in drying a PTA-containing wet cake. The first class of dryer used in the examples below was represented by the TORUSDISC TD 12-4 dryer (manufactured by Bepex International LLC, Minneapolis, Minnesota, USA). The TORUSDISC TD 12-4 dryer is an indirect heat exchanger having a heated dryer area of 27.6 square feet. The TORUSDISC TD 12-4 represents a class of dryers characterized by a single or twin shaft heated rotor, a heated jacket, and slow, gentle movement of solids through the dryer during drying. Other dryers in this class include the DISCOTHERM-B dryer (manufactured by LIST USA Inc., Charlotte, NC, USA), the HOLO-FLITE dryer (manufactured by Metso Minerals, Helsinki, Finland), the PORCUPINE processor (manufactured by Bethlehem Corp., Easton, PA, USA), the K-S NARA PADDLE dryer (manufactured by Komiine-Sanderson Engineering Corp., Peapack, NJ, USA), and the ROVACTOR dryer (manufactured by Buss-SMS- Canzler GmbH, Butzbach, Germany).
The second class of dryer used in the examples below was represented by the SOLIDAIRE dryer (manufactured by Bepex International LLC5 Minneapolis, Minnesota, USA). Two different models of the SOLIDAIRE dryer were used in the examples below: the SOLIDAIRE SJS 10-6 and the SOLIDAIRE SJS 8-4. The SOLIDAIRE dryers represent a class of dryers known as thin layer contact dryers, which are characterized by a heated jacket, a heated inner surface, and a paddle rotor having blades that can be angled, shaped, or oriented so as to impart centrifugal and axially forward forces to the material being dried. The SOLIDAIRE dryers are capable of producing a highly agitated thin layer of cake. Each of the SOLIDAIRE dryers employed can be direct and/or indirect heat exchangers. The SJS 10-6 dryer has a heated drying area of 15 square feet, and the SJS 8-4 has a heated drying area of 8 square feet. Another dryer in this class is the TURBODRYER (manufactured by VOMM S.P.A., Milan, Italy). EXAMPLE 3 - Dryer Residence Time
To compare the performance of the dryers described in Example 2, a total of 4 samples of the PTA wet cake containing 18 weight percent moisture, as prepared in Example 1, were dried in a TORUSDISC TD 12-4 dryer and a SOLIDAIRE SJS 10-6 dryer, two samples in each dryer. In each of the 4 runs, the wet cake was metered into the dryer with a screw feeder. The feed rate was varied from 27 pounds per hour per square foot of heated drying area (lbs/hr/ft2) to 93 lbs/hr/ft2. A vacuum system was employed during the drying procedure which removed the acid vapor from the dryer. Additionally, during the drying procedure the dryer was purged with nitrogen. After drying, the dried PTA was removed from the dryers via a rotary air lock valve, which allowed the dry powder to be removed from the dryer while maintaining a substantially constant level of pressure in the dryer. The dry PTA temperature, the moisture content, and the residence time of the dried PTA product were then measured. In each of the 4 runs, the jacket temperature of the dryer was maintained at 1800C during drying. The results are listed in Table 1 , below.
Table 1 - Effect of Dryer on Residence Time
Figure imgf000025_0001
As can be seen by looking at the results listed in Table 1, each of the two dryers was able to produce a dry PTA product having less than 0.1 weight percent moisture. However, it is clear that the SOLIDAIRE dryer provides shorter residence times than the TORUSDISC dryer, while achieving the same or better level of reduction in moisture. EXAMPLE 4 - Jacket Temperature and Feed Rate
The effect of the jacket temperature and feed rate on dry PTA temperature, dry PTA weight percent moisture, and dryer residence time was determined by performing drying operations on five samples of the PTA wet cake containing 11 weight percent moisture, as prepared in Example 1. For this determination, a SOLIDAIRE SJS 8-4 dryer was employed. Each sample in turn was metered to the dryer using a screw feeder. The feed rate for each of the five runs was varied from 75 lbs/hr/ft2 to 175 Ibs/hr/ft2. Additionally, the jacket temperature of the dryer was varied from 200°C (Runs 1-3) to 223°C (Run 4) and 244°C (Run 5). After drying, the dried PTA was removed from the dryer via a rotary air lock valve, which allowed the dry powder to be removed from the dryer while maintaining a substantially constant level of pressure in the dryer. The dry PTA temperature, the moisture content, and the residence time of the dried PTA product were then measured. The results are listed in Table 2, below.
Figure imgf000026_0001
As can be seen by looking at the results listed in Table 2, the feed rate in Run 3 was increased to 150 lbs/hr/ft2 while maintaining a jacket temperature of
2000C. This resulted in a dried PTA product having an unacceptably high level of moisture content (1.1 weight percent). However, as Runs 4 and 5 demonstrate, when the dryer jacket temperature is increased, the wet cake feed rate can also be increased without having a deleterious effect on the moisture content of the dried PTA product.
EXAMPLE 5 - Thermal Stability of Terephthalic Acid The thermal stability of terephthalic acid (TPA) was determined by performing thermal gravimetric analysis (TGA) on two samples of crude terephthalic acid (CTA) and two samples of PTA. One of the PTA samples and one of the CTA samples was tested in an air environment, while the other two samples were tested in a nitrogen environment. A modified version of ASTM method El 131-03 (Standard Test Method for Compositional Analysis by Thermogravimetry) was followed for this example. The method was modified by lowering the highest testing temperature to 3500C. The analyses were performed on a HI-RES TGA 2950 THERMOGRAVIMETRIC ANALYZER (manufactured by TA Instruments, New Castle, DE, USA). The scan rate employed in each analysis was 5°C per minute.
The results from the TGA analysis of TPA are shown in FIGS. 4 and 4a. FIG. 4 depicts the thermal degradation and/or sublimation of terephthalic acid over a temperature range starting at 00C and ending at 3500C5 while FIG. 4a is a magnified view of FIG. 4, depicting the thermal degradation and/or sublimation of TPA over a temperature range from 185°C to 285°C. As can be seen by looking at FIG. 4a, it is apparent that severe thermal degradation and/or sublimation of the TPA begins to occur at temperatures greater than about 250°C. Thermal degradation begins to occur at about 25O0C whether the sample is CTA or PTA, and occurs in both air environments and nitrogen environments.
NUMERICAL RANGES
The present description uses numerical ranges to quantify certain parameters relating to the invention. It should be understood that when numerical ranges are provided, such ranges are to be construed as providing literal support for claim limitations that only recite the lower value of the range as well as claims limitation that only recite the upper value of the range. For example, a disclosed numerical range of 10 to 100 provides literal support for a claim reciting "greater than 10" (with no upper bounds) and a claim reciting "less than 100" (with no lower bounds). The present description uses specific numerical values to quantify certain parameters relating to the invention, where the specific numerical values are not expressly part of a numerical range. It should be understood that each specific numerical value provided herein is to be construed as providing literal support for a broad, intermediate, and narrow range. The broad range associated with each specific numerical value is the numerical value plus and minus 60 percent of the numerical value, rounded to two significant digits. The intermediate range associated with each specific numerical value is the numerical value plus and minus 30 percent of the numerical value, rounded to two significant digits. The narrow range associated with each specific numerical value is the numerical value plus and minus 15 percent of the numerical value, rounded to two significant digits. For example, if the specification describes a specific temperature of 62°F, such a description provides literal support for a broad numerical range of 25°F to 99°F (62°F +/- 37°F), an intermediate numerical range of 43°F to 810F (62°F +/- 19°F), and a narrow numerical range of 530F to 71°F (62°F +/- 9°F). These broad, intermediate, and narrow numerical ranges should be applied not only to the specific values, but should also be applied to differences between these specific values. Thus, if the specification describes a first pressure of 1 10 psia and a second pressure of 48 psia (a difference of 62 psi), the broad, intermediate, and narrow ranges for the pressure difference between these two streams would be 25 to 99 psi, 43 to 81 psi, and 53 to 71 psi, respectively.
DEFINITIONS
As used herein, the terms "comprising," "comprises," and "comprise" are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.
As used herein, the terms "including," "includes," and "include" have the same open-ended meaning as "comprising," "comprises," and "comprise." As used herein, the terms "having," "has," and "have" have the same open-ended meaning as "comprising," "comprises," and "comprise."
As used herein, the terms "containing," "contains," and "contain" have the same open-ended meaning as "comprising," "comprises," and "comprise."
As used herein, the terms "a," "an," "the," and "said" mean one or more. As used herein, the term "and/or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.
CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS
The forms of the invention described above are to be used as illustration only, and should not be used in a limiting sense to interpret the scope of the present invention. Obvious modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.
The inventors hereby state their intent to rely on the Doctrine of
Equivalents to determine and assess the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.

Claims

What is claimed is:
1. A method for drying solid particles comprising a carboxylic acid, said method comprising: (a) introducing a wet cake comprising said solid particles into a drying zone; and
(b) drying said wet cake in said drying zone to thereby produce a substantially dry product comprising at least a portion of said solid particles, wherein said solid particles have an average residence time of less than about 7 minutes in said drying zone, and wherein said solid particles have an exit temperature of less than about 2500C upon exiting said drying zone.
2. The method of claim 1, wherein said carboxylic acid comprises an aromatic dicarboxylic acid.
3. The method of claim 1, wherein said carboxylic acid comprises terephthalic acid.
4. The method of claim 1, wherein said solid particles comprise particles of crude terephthalic acid.
5. The method of claim 1, wherein said solid particles comprise particles of purified terephthalic acid.
6. The method of claim 1, wherein said solid particles have a mean particle size in the range of from about 1 to about 500 microns.
7. The method of claim 1, wherein said substantially dry product comprises less than about 1 weight percent liquid.
8. The method of claim 1 , wherein said substantially dry product comprises less than about 0.5 weight percent liquid.
9. The method of claim 1, wherein said solid particles have an average residence time of less than about 5 minutes in said drying zone.
10. The method of claim 1, wherein said solid particles have an average residence time of less than about 3 minutes in said drying zone.
11. The method of claim 1, wherein said exit temperature is in the range of from about 105 to about 2400C.
12. The method of claim 1, wherein said exit temperature is in the range of from about 110 to about 2000C.
13. The method of claim 1, wherein said substantially dry product comprises less than 0.2 weight percent liquid, wherein said solid particles have an average residence time of less than 2 minutes in said drying zone, and wherein said exit temperature is in the range of from 115 to 1750C.
14. The method of claim 1, wherein said wet cake comprises in the range of from about 2 to about 25 weight percent liquid.
15. The method of claim 1, wherein said wet cake further comprises acetic acid, benzoic acid, and/or water.
16. The method of claim 1, wherein said wet cake has a temperature in the range of from about 20 to about 2000C immediately prior to entering said drying zone.
17. The method of claim I5 wherein said wet cake comprises in the range of from 4 to 20 weight percent liquid, and wherein said wet cake has a temperature in the range of from 65 to 1050C immediately prior to entering said drying zone.
18. The method of claim 1, wherein said drying zone is defined within a contact dryer.
19. The method of claim 18, wherein said wet cake is fed to said drying zone at a feed rate of at least about 20 lbs/hour per square foot of heated surface area during said drying.
20. The method of claim 18, wherein said wet cake is fed to said drying zone at a feed rate in the range of from about 40 to about 175 lbs/hour per square foot of heated surface area during said drying.
21. The method of claim 18, wherein said dryer comprises at least one jacket, wherein the jacket temperature of said dryer is maintained in the range of from about 120 to about 2800C during said drying.
22. The method of claim 21, wherein the jacket temperature of said dryer is maintained in the range of from about 200 to about 2400C during said drying.
23. The method of claim 18, wherein said dryer comprises a paddle rotor comprising a plurality of radially extending paddles.
24. The method of claim 23, wherein said paddle rotor rotates at a speed such that the tips of said paddles travel at a speed of at least about 10 cm/s.
25. The method of claim 23, wherein said dryer further comprises a jacketed cylinder presenting a heated inner surface, wherein said paddle rotor is substantially disposed in said jacketed cylinder.
5 26. The method of claim 25, wherein during said drying said paddle rotor is operable to facilitate contact of said solid particles with said heated inner surface and to facilitate movement of said solid particles through said jacketed cylinder.
10 27. The method of claim 18, wherein said dryer is a thin layer contact dryer.
28. The method of claim 18, wherein said dryer is operated under vacuum conditions during said drying.
15
29. The method of claim 18, wherein the pressure in said dryer is maintained in the range of from about 50 to about 1000 torr during said drying.
30. The method of claim 18, wherein said dryer further comprises a 20 vacuum seal device through which said solid particles exit said drying zone.
31. The method of claim I5 step (b) further comprising introducing a drying gas into said drying zone to aid in drying at least a portion of said wet cake, wherein said drying gas has an inlet temperature of at least about 1000C.
25
32. A method for producing a substantially dry crude terephthalic acid (CTA) particulate product, said method comprising:
(a) oxidizing an aromatic compound in an oxidation zone to thereby produce a slurry comprising solid CTA particles; (b) treating at least a portion of said slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of said solid CTA particles; and
(c) drying at least a portion of said wet cake in a drying zone to thereby produce said substantially dry CTA particulate product, wherein said
CTA particles have an average residence time of less than about 7 minutes in said drying zone, and wherein said CTA particles have an exit temperature of less than about 2500C upon exiting said drying zone.
33. The method of claim 32, wherein said substantially dry CTA particulate product comprises less than about 1 weight percent liquid.
34. The method of claim 32, wherein said exit temperature is in the range of from about 1 10 to about 2000C.
35. The method of claim 32, wherein said wet cake comprises in the range of from about 2 to about 25 weight percent water.
36. The method of claim 32, wherein said aromatic compound comprises para-xylene.
37. The method of claim 32, wherein at least a portion of said product isolation zone is defined within a vacuum filter.
38.. The method of claim 32, wherein said drying zone is defined within a contact dryer.
39. The method of claim 38, wherein said wet cake is fed to said drying zone at a feed rate of at least about 20 lbs/hour per square foot of heated surface area during said drying.
40. The method of claim 38, wherein said dryer comprises at least one jacket, wherein the jacket temperature of said dryer is maintained in the range of from about 120 to about 2800C.
41. The method of claim 32, further comprising using a common vacuum source to create a vacuum in said product isolation zone and said drying zone during said treating and said drying.
42. A method for producing a substantially dry purified terephthalic acid (PTA) particulate product, said method comprising: (a) oxidizing an aromatic compound in an oxidation zone to thereby produce a first slurry comprising solid crude terephthalic acid (CTA) particles; (b) subjecting at least a portion of said CTA particles to purification in a purification zone to thereby produce a second slurry comprising solid PTA particles; (c) treating at least a portion of said second slurry in a product isolation zone to thereby produce a wet cake comprising at least a portion of said PTA particles; and
(d) drying said wet cake in a drying zone to thereby produce said substantially dry PTA particulate product, wherein said PTA particles have an average residence time of less than about 7 minutes in said drying zone, and wherein said PTA particles have an exit temperature of less than about 250°C upon exiting said drying zone.
43. The method of claim 42, wherein said substantially dry PTA particulate product comprises less than about 1 weight percent liquid.
44. The method of claim 42, wherein said exit temperature is in the range of from about 110 to about 2000C.
45. The method of claim 42, wherein said wet cake comprises in the range of from about 2 to about 25 weight percent water.
46. The method of claim 42, wherein said purification includes subjecting at least a portion of said CTA particles to further oxidation and/or hydrogenation.
47. The method of claim 42, wherein said drying zone is defined within a contact dryer.
48. The method of claim 47, wherein said wet cake is fed to said drying zone at a feed rate of at least about 20 lbs/hour per square foot of heated surface area during said drying.
49. The method of claim 47, wherein said dryer comprises at least one jacket, wherein the jacket temperature of said dryer is maintained in the range of from about 120 to about 2800C.
50. The method of claim 42, further comprising using a common vacuum source to create a vacuum in said product isolation zone and said drying zone during said treating and said drying.
51. A method for drying a wet cake comprising terephthalic acid (TPA), said method comprising:
(a) introducing said wet cake into a dryer; and (b) drying said wet cake in said dryer to thereby produce a dry TPA product, wherein said TPA has an average residence time in said dryer of less than about 7 minutes, and wherein said dry TPA product has a temperature in the range of from about 105 to about 240°C upon exiting said dryer.
52. The method of claim 51, wherein said TPA has an average residence time in said dryer of less than about 5 minutes.
53. The method of claim 51, wherein said dry TPA product has a temperature in the range of from about 125 to about 2000C upon exiting said dryer.
54. The method of claim 51, wherein said wet cake comprises in the range of from 1 to about 35 weight percent moisture, and wherein said dry TPA product comprises less than 1 weight percent moisture.
55. The method of claim 51, wherein said terephthalic acid is crude terephthalic acid.
56. The method of claim 51, wherein said terephthalic acid is purified terephthalic acid.
57. The method of claim 51, wherein said dryer comprises a thin layer contact dryer having a heated inner surface.
58. The method of claim 57, wherein said wet cake is fed to said dryer at a feed rate of at least about 35 lbs/hour per square foot of said heated inner surface during said drying.
59. The method of claim 51, wherein said dryer comprises a jacket, and wherein the jacket temperature of said dryer is maintained in the range of from about 120 to about 270°C during said drying.
60. The method of claim 51, wherein said dryer comprises a paddle rotor comprising a plurality of blades, wherein at least a portion of said blades are angled, shaped, and/or oriented so as to impart centrifugal and axially forward forces on said wet cake.
PCT/US2007/004935 2006-03-01 2007-02-27 Method and apparatus for drying carboxylic acid WO2007103025A2 (en)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
US77790806P 2006-03-01 2006-03-01
US77790606P 2006-03-01 2006-03-01
US60/777,908 2006-03-01
US60/777,906 2006-03-01
US11/701,129 2007-02-01
US11/701,129 US8173836B2 (en) 2006-03-01 2007-02-01 Method and apparatus for drying carboxylic acid
US11/701,128 US8173835B2 (en) 2006-03-01 2007-02-01 Method and apparatus for drying carboxylic acid
US11/701,128 2007-02-01

Publications (3)

Publication Number Publication Date
WO2007103025A2 true WO2007103025A2 (en) 2007-09-13
WO2007103025A3 WO2007103025A3 (en) 2007-11-22
WO2007103025A8 WO2007103025A8 (en) 2008-01-17

Family

ID=38472865

Family Applications (2)

Application Number Title Priority Date Filing Date
PCT/US2007/004973 WO2007103040A2 (en) 2006-03-01 2007-02-27 Method and apparatus for drying carboxylic acid
PCT/US2007/004935 WO2007103025A2 (en) 2006-03-01 2007-02-27 Method and apparatus for drying carboxylic acid

Family Applications Before (1)

Application Number Title Priority Date Filing Date
PCT/US2007/004973 WO2007103040A2 (en) 2006-03-01 2007-02-27 Method and apparatus for drying carboxylic acid

Country Status (2)

Country Link
US (2) US8173835B2 (en)
WO (2) WO2007103040A2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102538426A (en) * 2012-02-29 2012-07-04 南京天华化学工程有限公司 Continuous drying process and equipment for cyclohexanone oximation catalyst

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7452522B2 (en) * 2003-06-05 2008-11-18 Eastman Chemical Company Extraction process for removal of impurities from an oxidizer purge stream in the synthesis of carboxylic acid
US7282151B2 (en) * 2003-06-05 2007-10-16 Eastman Chemical Company Process for removal of impurities from mother liquor in the synthesis of carboxylic acid using pressure filtration
US7351396B2 (en) * 2003-06-05 2008-04-01 Eastman Chemical Company Extraction process for removal of impurities from an aqueous mixture
US7410632B2 (en) * 2003-06-05 2008-08-12 Eastman Chemical Company Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid
US7494641B2 (en) * 2003-06-05 2009-02-24 Eastman Chemical Company Extraction process for removal of impurities from an oxidizer purge stream in the synthesis of carboxylic acid
US7888530B2 (en) * 2004-09-02 2011-02-15 Eastman Chemical Company Optimized production of aromatic dicarboxylic acids
US20070238899A9 (en) * 2004-09-02 2007-10-11 Robert Lin Optimized production of aromatic dicarboxylic acids
US7959879B2 (en) 2004-09-02 2011-06-14 Grupo Petrotemex, S.A. De C.V. Optimized production of aromatic dicarboxylic acids
US7402694B2 (en) * 2005-08-11 2008-07-22 Eastman Chemical Company Process for removal of benzoic acid from an oxidizer purge stream
US7569722B2 (en) * 2005-08-11 2009-08-04 Eastman Chemical Company Process for removal of benzoic acid from an oxidizer purge stream
US20070203359A1 (en) * 2006-03-01 2007-08-30 Philip Edward Gibson Versatile oxidation byproduct purge process
US7897808B2 (en) * 2006-03-01 2011-03-01 Eastman Chemical Company Versatile oxidation byproduct purge process
US7880032B2 (en) * 2006-03-01 2011-02-01 Eastman Chemical Company Versatile oxidation byproduct purge process
US7863481B2 (en) * 2006-03-01 2011-01-04 Eastman Chemical Company Versatile oxidation byproduct purge process
FR2947044B1 (en) * 2009-06-23 2013-06-07 Asten Assistance Services Traitements Environnement Nucleaire DEVICE FOR DRYING WASTE BY EVAPORATION AND CORRESPONDING METHOD.
WO2016128801A1 (en) * 2015-02-12 2016-08-18 Sorgente Antonio Dynamic discontinuous dryer
DE102017002400A1 (en) * 2017-03-14 2018-09-20 Colak GmbH Biomass dryer and method for drying biomass
US11117093B2 (en) * 2017-09-14 2021-09-14 Perma Pure Llc Method for a portable sampling system
CN114111234B (en) * 2021-11-14 2022-07-15 江苏先锋干燥工程有限公司 Ferric phosphate dehydration crystallization equipment and operation method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152947A (en) * 1962-09-18 1964-10-13 Colgate Palmolive Co Process for drying higher fatty acid sarcosines
GB1470574A (en) * 1974-03-28 1977-04-14 Monsanto Co Resin processing method
US5271163A (en) * 1992-10-05 1993-12-21 Bepex Corporation System for treating flowable materials
EP1402942A1 (en) * 2001-05-15 2004-03-31 Mitsubishi Chemical Corporation Process for producing a compound
US20050000108A1 (en) * 2003-07-02 2005-01-06 Ragnarsson Anders T. Sludge dryer

Family Cites Families (62)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3425135A (en) * 1964-09-11 1969-02-04 Strong Mfg Co Scott Rotary solids processing apparatus and method
US3943233A (en) * 1974-02-20 1976-03-09 Engelhard Minerals & Chemicals Corporation Processing finely divided solids on a continuous vacuum belt filter
US4158738A (en) * 1977-05-26 1979-06-19 E. I. Du Pont De Nemours And Company Process for the production of fiber-grade terephthalic acid
US4330676A (en) * 1977-07-04 1982-05-18 Imperial Chemical Industries Limited Oxidation process
US4161578A (en) * 1978-05-12 1979-07-17 Bepex Corporation Process for solid phase polymerization of polyester
DE2840481A1 (en) * 1978-09-16 1980-03-27 Bayer Ag THICK LAYER CONTACT DRYER
US4219669A (en) * 1979-06-08 1980-08-26 Jgc Corporation Method of treating mother liquor of reaction in terephthalic acid production
IT1129759B (en) * 1980-01-23 1986-06-11 Montedison Spa METHOD TO RECOVER IN ACTIVE FORM THE COMPONENTS OF THE CATALYTIC SYSTEM OF THE SYNTHESIS OF TEREPHTHALIC ACID
DE3150653A1 (en) * 1981-01-10 1982-09-02 Henri Gerhard Willem Bozeat Wellingborough Northamptonshire Pierson "HORIZONTAL VACUUM BAND FILTER"
JPS60112804A (en) * 1983-11-24 1985-06-19 Chisso Corp Post-treatment device for polyolefin powder
US4658891A (en) * 1984-01-05 1987-04-21 Willow Technology, Inc. Method and apparatus for thermally processing viscous, shear sensitive materials
US4914230A (en) * 1986-07-28 1990-04-03 Amoco Corporation Catalyst recovery method
US4769489A (en) * 1986-07-28 1988-09-06 Amoco Corporation Catalyst recovery method
US4792621A (en) * 1986-07-28 1988-12-20 Amoco Corporation Method for continuous production of aromatic carboxylic acid
US5100510A (en) * 1988-04-28 1992-03-31 Colgate-Palmolive Company Apparatus for manufacturing high bulk density particulate fabric softening synthetic anionic organic detergent compositions
US4894117A (en) * 1988-04-28 1990-01-16 Colgate-Palmolive Company Process for manufacturing high bulk density particulate fabric softening synthetic anionic organic detergent compositions
US5043007A (en) * 1988-08-25 1991-08-27 Davis Bobby G Process for the production of fertilizer and the fertilizer produced thereby
US4939297A (en) * 1989-06-05 1990-07-03 Eastman Kodak Company Extraction process for removal of impurities from terephthalic acid filtrate
GB9104776D0 (en) * 1991-03-07 1991-04-17 Ici Plc Process for the production of terephthalic acid
US5200557A (en) * 1991-04-12 1993-04-06 Amoco Corporation Process for preparation of crude terephthalic acid suitable for reduction to prepare purified terephthalic acid
US5175355A (en) * 1991-04-12 1992-12-29 Amoco Corporation Improved process for recovery of purified terephthalic acid
GB9310070D0 (en) * 1992-05-29 1993-06-30 Ici Plc Process for the production of purified terephthalic acid
GB9302333D0 (en) * 1993-02-05 1993-03-24 Ici Plc Filtration process
JPH06327915A (en) * 1993-05-24 1994-11-29 Mitsui Petrochem Ind Ltd Method for recovering crystal from slurry and device therefor
US5767311A (en) * 1995-06-07 1998-06-16 Glitsch International, Inc. Method and apparatus for preparing purified terephtalic acid
US6054610A (en) * 1995-06-07 2000-04-25 Hfm International, Inc. Method and apparatus for preparing purified terephthalic acid and isophthalic acid from mixed xylenes
US5840968A (en) * 1995-06-07 1998-11-24 Hfm International, Inc. Method and apparatus for preparing purified terephthalic acid
US6013835A (en) * 1995-06-07 2000-01-11 Hfm International, Inc. Method and apparatus for preparing purified terephthalic acid
JP3729284B2 (en) * 1995-09-22 2005-12-21 三菱瓦斯化学株式会社 Method for producing high purity terephthalic acid
EP0871603B1 (en) * 1995-12-30 2001-09-05 Sunkyong Industries Co., Ltd. Process for manufacturing terephthalic acid
US6031128A (en) * 1995-12-30 2000-02-29 Sunkyong Industries Co., Ltd. Process for manufacturing terephthalic acid
US5840965A (en) * 1996-06-24 1998-11-24 E. I. Du Pont De Nemours And Company Process for the production of purified telephthalic acid
JP3757995B2 (en) * 1996-07-12 2006-03-22 三菱瓦斯化学株式会社 Method for producing high purity isophthalic acid
US5840985A (en) * 1996-07-18 1998-11-24 Stepan Company Process for the conversion of fatty amides to amines
KR100264749B1 (en) 1997-02-17 2000-09-01 나까니시 히로유끼 Production of highly pure terephthalic acid
KR20000075766A (en) * 1997-02-27 2000-12-26 메리 이. 보울러 Production of Terephthalic Acid
US5877271A (en) * 1997-04-18 1999-03-02 The Dow Chemical Company Finishing process for syndiotactic vinyl aromatic polymers
US6150553A (en) * 1998-08-11 2000-11-21 E. I. Du Pont De Nemours And Company Method for recovering methyl acetate and residual acetic acid in the production acid of pure terephthalic acid
US6245939B1 (en) * 1998-11-30 2001-06-12 E. I. Du Pont De Nemours And Company Process for producing highly pure aromatic carboxylic acids
US6153790A (en) * 1998-12-01 2000-11-28 Shell Oil Company Method to produce aromatic dicarboxylic acids using cobalt and zirconium catalysts
US6143926A (en) * 1999-09-21 2000-11-07 E. I. Du Pont De Nemours And Company Process for producing pure terephthalic acid with improved recovery of precursors, solvent and methyl acetate
JP3808672B2 (en) * 1999-11-26 2006-08-16 東洋製罐株式会社 Industrial recovery method of terephthalic acid from recovered pulverized polyethylene terephthalate
US6639104B2 (en) * 1999-12-10 2003-10-28 Inca International S.P.A. Process for the recovery of purified terephthalic acid (PTA)
WO2001053246A1 (en) * 2000-01-21 2001-07-26 Bp Corporation North America Inc. Production of high purity aromatic carboxylic acid by oxidation in benzoic acid and water solvent
EP1409445A2 (en) * 2000-01-25 2004-04-21 Inca International S.P.A. Process for the recovery of crude terephthalic acid (cta)
US6655531B1 (en) * 2000-05-23 2003-12-02 Baker Hughes Incorporated Pressure filtration device
JP4788023B2 (en) * 2000-06-27 2011-10-05 三菱瓦斯化学株式会社 Method for recovering catalyst components from liquid phase oxidation reaction mother liquor
US6765113B2 (en) * 2000-07-19 2004-07-20 E.I. Du Pont De Nemours And Company Production of aromatic carboxylic acids
JP4809534B2 (en) * 2001-01-22 2011-11-09 三菱瓦斯化学株式会社 Process for producing aromatic carboxylic acid
WO2002080685A1 (en) * 2001-04-09 2002-10-17 Cargill Incorporated Process for the production of masa flour and dough
US7196215B2 (en) * 2001-06-04 2007-03-27 Eastman Chemical Company Process for the production of purified terephthalic acid
US6638558B2 (en) * 2001-09-27 2003-10-28 Cargill, Incorporated Masa flavored cereal germ and a process for making same
US6935051B2 (en) * 2002-11-22 2005-08-30 Charles L. Stock Heating and drying apparatus for particulate material
US7074954B2 (en) * 2002-12-09 2006-07-11 Eastman Chemical Company Process for the oxidative purification of terephthalic acid
US7132566B2 (en) * 2003-09-22 2006-11-07 Eastman Chemical Company Process for the purification of a crude carboxylic acid slurry
US7193109B2 (en) * 2003-03-06 2007-03-20 Eastman Chemical Company Process for production of a carboxylic acid/diol mixture suitable for use in polyester production
US7381386B2 (en) * 2003-06-05 2008-06-03 Eastman Chemical Company Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid
US7410632B2 (en) * 2003-06-05 2008-08-12 Eastman Chemical Company Extraction process for removal of impurities from mother liquor in the synthesis of carboxylic acid
US7282151B2 (en) * 2003-06-05 2007-10-16 Eastman Chemical Company Process for removal of impurities from mother liquor in the synthesis of carboxylic acid using pressure filtration
US7214760B2 (en) * 2004-01-15 2007-05-08 Eastman Chemical Company Process for production of a carboxylic acid/diol mixture suitable for use in polyester production
US7546747B2 (en) * 2004-01-15 2009-06-16 Eastman Chemical Company Process for production of a dried carboxylic acid cake suitable for use in polyester production
US7888530B2 (en) * 2004-09-02 2011-02-15 Eastman Chemical Company Optimized production of aromatic dicarboxylic acids

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3152947A (en) * 1962-09-18 1964-10-13 Colgate Palmolive Co Process for drying higher fatty acid sarcosines
GB1470574A (en) * 1974-03-28 1977-04-14 Monsanto Co Resin processing method
US5271163A (en) * 1992-10-05 1993-12-21 Bepex Corporation System for treating flowable materials
EP1402942A1 (en) * 2001-05-15 2004-03-31 Mitsubishi Chemical Corporation Process for producing a compound
US20050000108A1 (en) * 2003-07-02 2005-01-06 Ragnarsson Anders T. Sludge dryer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102538426A (en) * 2012-02-29 2012-07-04 南京天华化学工程有限公司 Continuous drying process and equipment for cyclohexanone oximation catalyst

Also Published As

Publication number Publication date
WO2007103025A8 (en) 2008-01-17
US8173835B2 (en) 2012-05-08
US20070204479A1 (en) 2007-09-06
WO2007103040A2 (en) 2007-09-13
US20070208196A1 (en) 2007-09-06
US8173836B2 (en) 2012-05-08
WO2007103040A3 (en) 2007-11-22
WO2007103025A3 (en) 2007-11-22

Similar Documents

Publication Publication Date Title
US8173836B2 (en) Method and apparatus for drying carboxylic acid
US7462736B2 (en) Methods and apparatus for isolating carboxylic acid
EP1989165B1 (en) Carboxylic acid production process
US20070208199A1 (en) Methods and apparatus for isolating carboxylic acid
US7847121B2 (en) Carboxylic acid production process
US7956215B2 (en) Versatile oxidation byproduct purge process
EP1989167A1 (en) Methods and apparatus for producing a low-moisture carboxylic acid wet cake
US7880032B2 (en) Versatile oxidation byproduct purge process
PT1888501E (en) An enriched terephthalic acid composition
US7863481B2 (en) Versatile oxidation byproduct purge process
US7902395B2 (en) Versatile oxidation byproduct purge process
US20060264658A1 (en) Process to produce an enriched composition
BRPI0610238A2 (en) isophthalic acid composition
JP2008545806A (en) Method for enriching carboxylic acid composition
BRPI0708390A2 (en) process for treating a purge feed stream
CA2607156A1 (en) A process to produce a post catalyst removal composition

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 07751675

Country of ref document: EP

Kind code of ref document: A2