WO2014189818A1 - Récupération de puissance destinée à être utilisée dans le démarrage ou le redémarrage d'un procédé de production d'acide téréphtalique pur - Google Patents

Récupération de puissance destinée à être utilisée dans le démarrage ou le redémarrage d'un procédé de production d'acide téréphtalique pur Download PDF

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Publication number
WO2014189818A1
WO2014189818A1 PCT/US2014/038546 US2014038546W WO2014189818A1 WO 2014189818 A1 WO2014189818 A1 WO 2014189818A1 US 2014038546 W US2014038546 W US 2014038546W WO 2014189818 A1 WO2014189818 A1 WO 2014189818A1
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Prior art keywords
stream
gaseous
icocgt
heat
compressor
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PCT/US2014/038546
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English (en)
Inventor
Clive T. ROBINS
Harald B. Carrick
Graham Aird
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Invista Technologies S.À.R.L.
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Priority claimed from US13/901,666 external-priority patent/US20130255259A1/en
Application filed by Invista Technologies S.À.R.L. filed Critical Invista Technologies S.À.R.L.
Publication of WO2014189818A1 publication Critical patent/WO2014189818A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C6/00—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use
    • F02C6/18—Plural gas-turbine plants; Combinations of gas-turbine plants with other apparatus; Adaptations of gas-turbine plants for special use using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
    • F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
    • F01K25/14—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours using industrial or other waste gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C3/00—Gas-turbine plants characterised by the use of combustion products as the working fluid
    • F02C3/20—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products
    • F02C3/22—Gas-turbine plants characterised by the use of combustion products as the working fluid using a special fuel, oxidant, or dilution fluid to generate the combustion products the fuel or oxidant being gaseous at standard temperature and pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B1/00—Methods of steam generation characterised by form of heating method
    • F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
    • F22B1/18—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines
    • F22B1/1807—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines
    • F22B1/1815—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being a hot gas, e.g. waste gas such as exhaust gas of internal-combustion engines using the exhaust gases of combustion engines using the exhaust gases of gas-turbines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2220/00—Application
    • F05D2220/60—Application making use of surplus or waste energy
    • F05D2220/62—Application making use of surplus or waste energy with energy recovery turbines

Definitions

  • This invention relates to a method for recovering power from the gaseous stream ("off-gas") produced by an oxidation reaction, for example the oxidations of para-xylene (pX) to terephthalic acid (TA) and dimethyl terephthalate (DMT) or of cyclohexane to cyclohexanone / cyclohexanol.
  • an oxidation reaction system comprising a power recovery system and a method for the recovery of energy as a high grade heat source such as high pressure steam, hot oil or the like, for use in starting, running or re-starting a PTA production process.
  • acetic acid, molecular oxygen in the form of air, para-xylene and catalyst are fed continuously into the oxidation reactor at elevated temperature and pressure, typically a temperature from about 150°C to about 250°C and a pressure from about 600 kPa to about 2500 kPa.
  • Para-xylene oxidation produces a high-pressure gaseous stream (or "off- gas") which comprises nitrogen, unreacted oxygen, carbon dioxide, carbon monoxide and, where bromine is used as a promoter, methyl bromide.
  • off- gas gaseous stream
  • the acetic acid solvent is frequently allowed to vaporize to control the reaction temperature and is removed in the gaseous stream. This vapour is typically condensed and most of the condensate is refluxed to the reactor, with some condensate being withdrawn to control reactor water
  • the portion of the gaseous stream which is not condensed is either vented, or passed through a catalytic combustion unit (CCU) to form an
  • Catalytic combustors have been deployed on TA plants typically upstream of an expander. Their function is to catalytically combust volatile organic compounds (VOC's) and carbon monoxide.
  • VOC's volatile organic compounds
  • the gaseous stream from the reactor contains a significant amount of energy. This energy can be recovered to offset, at least partially, the cost of obtaining the high temperatures and pressures required in the oxidation reactor.
  • WO 96/11899 and JP 8-155265 disclose directing the high pressure gaseous stream to a means for recovering energy, for example an expander, which is connected to an electric generator or other equipment requiring mechanical work, such as a compressor. Power recovery using an expander (for example as disclosed in WO 96/39595) is conventionally carried out at temperatures from about
  • the TA manufacturing process requires a source of heat above 300°C to heat the feed stream to the Purification plant hydrogenation reactor.
  • This duty is typically accomplished using a source of High Pressure (HP) Steam (for example at about 100 bara, 3 1°C) or hot oil at similar or even higher temperatures.
  • HP steam for this purpose is imported from a Utility provider or raised on site following installation of a packaged boiler assembly.
  • Improvements have been made to the energy efficiency of the PTA production process, however, the improvements comprise multiple and separate systems, adding additional complexity to the normal operation of the production process. Further, additional sources of high grade heat are required to start-up the production process or when the oxidation reactor is not in normal operation, such as an unplanned process interruption or stop ("Trip").
  • Trip process interruption or stop
  • the invention disclosed herein provides for improved processes for the production of PTA, and specifically to modifications of the operation of Internal Combustion Open Cycle Gas Turbines ICOCGTs to improve the thermodynamic efficiency of the terephthalic acid purification step of the PTA production process. As disclosed herein, the process generates high grade heat while eliminating the requirement for separate sources of high temperature heat or the provision of a high grade heat source utility system for the PTA production process.
  • a process for recovering power from a paraxylene - air oxidation reaction to produce terephthalic acid, where the oxidation reaction produces a gaseous stream comprises: (a) heating the gaseous stream to a temperature of at least 600°C; (b) sending the gaseous stream to an expander that drives a compressor, wherein the compressor compresses air which is fed to the oxidation reactor and the expander emits a gaseous vent stream; (c) feeding the gaseous vent stream to a heat recovery system to produce recovered heat; and (d) generating high grade heat from the recovered heat.
  • the expander can drive the compressor via a shaft that couples the two together.
  • the heat recovery system can be a heat exchanger or a combustor feed interchanger.
  • the high grade heat can be high pressure steam or hot oil.
  • the high grade heat generated can be used, for example, when the oxidation reactor operation is interrupted or experiences a process upset ("Trip") (which prevents the generation and reuse of energy from the process itself) to maintain the terephthalic acid purification stage and subsequently to restart the oxidation reactor.
  • Trip process upset
  • a paraxylene - air oxidation reaction to produce terephthalic acid system comprises: (a) an oxidation reactor comprising an oxidant inlet and a gaseous stream outlet, wherein the reactor emits a gaseous stream from the gaseous stream outlet; (b) a power recovery system connected to the gaseous stream outlet comprising: (i) a heater for receiving and heating the gaseous stream connected downstream of the gaseous stream outlet; and (ii) an expander positioned downstream of the heater that drives a compressor, wherein the compressor produces a compressed air stream and the expander emits a gaseous vent stream; and (c) a heat recovery system for receiving the gaseous vent stream and producing a high grade heat stream.
  • the heat recovery system can be a heat exchanger or a combustor feed interchanger.
  • the expander can drive the compressor via a shaft that couples the two together.
  • the heat stream can be used, for example, when the oxidation reactor operation is interrupted or experiences a process upset ("Trip") (which prevents the generation and reuse of energy from the process itself) to maintain the terephthalic acid purification stage and subsequently to restart the oxidation reactor.
  • Trip process upset
  • a process for maintaining the operation of a terephthalic acid oxidation plant during a process interruption comprises: (a) retaining a concentration of oxygen in a first combustor sufficient to sustain combustion and generate a combusted gas stream; (b) feeding the combusted gas stream to an expander, which produces a vent gas stream; (c) feeding the vent gas stream to a heat recovery system, with an optional auxiliary combustor, to produce recovered heat; and (d) using the recovered heat to maintain the operation of the terephthalic acid oxidation plant duties.
  • the recovered heat can be high pressure steam or hot oil.
  • the recovered heat can be used in the terephthalic acid purification stage, oxidation stage to start-up an oxidation reaction, re-start an oxidation reaction, or a combination.
  • Gaseous stream gas stream produced from an oxidation reaction.
  • Gaseous vent stream gas stream that emits from an expander.
  • Figure 1 is a schematic diagram of one aspect of the process.
  • Figure 2 is a schematic diagram that illustrates an interrupted oxidation reaction where the compressed air by-passes the oxidation reactor and is fed directly to the combustion chamber and expander.
  • a generator can be attached to the expander.
  • the net power generated can be used to offset the power requirement of the PTA plant.
  • Surplus power can be exported from the plant.
  • the present invention can be characterized by a process for recovering power from an oxidation reaction that produces a gaseous stream.
  • the process comprises: (a) heating the gaseous stream to a temperature of at least 600°C; (b) sending the gaseous stream to an expander that drives a compressor, wherein the compressor compresses air which is fed to the reactor and the expander emits a gaseous vent stream; (c) feeding the gaseous vent stream to a heat recovery system to produce recovered heat; and (d) generating high grade heat from the recovered heat.
  • the high grade heat can be used in part at least to heat high temperature process streams in the process plant.
  • terephthalic acid air is fed to an oxidation reactor wherein paraxylene is oxidized to terephthalic acid in a reaction whose liquor comprises acetic acid, paraxylene, cobalt acetate, manganese acetate and hydrogen bromide where the crude terephthalic acid is generated as a solid in the reaction slurry.
  • the slurry is typically cooled in a series of crystallisers and then isolated by solid-liquid using a suitable device such as a rotary drum filter, a belt filter or a centrifuge.
  • the acetic acid-wet TA cake is then optionally either dried to form a dry crude terephthalic acid or is washed using water to create a water-wet TA cake.
  • the resulting dry or water-wet cake is slurried in water and heated to sufficient temperature to dissolve the (relatively insoluble) TA in water. This is typically done industrially at a temperature of above 230 degrees C.
  • the high grade heat generated from the use of the gas turbine can be used to heat high temperature streams in a terephthalic acid purification process and TA oxidation process where temperatures of >230°C are required.
  • the expander can drive the compressor via a shaft that couples the two together.
  • the heat recovery system can be a heat exchanger or a combustor feed interchanger.
  • the high grade heat can be high pressure steam or hot oil.
  • an auxiliary combustor can be used to heat the gaseous vent stream prior to feeding the stream to a heat recovery system.
  • the high grade heat can also be used to heat high temperature streams to maintain the terephthalic acid purification stage and subsequently to restart the oxidation reactor when the oxidation reactor operation is interrupted or experiences a process upset ("Trip") which prevents the generation and reuse of energy from the process itself.
  • Trip process upset
  • sufficient high pressure steam or hot oil can continue to be supplied to the production process, even if the oxidation reaction exotherm is not recovered.
  • steam raised by the combustor can be used, when the oxidation reactor operation is interrupted or experiences a process upset, to maintain the terephthalic acid purification state in operation and subsequently to restart the oxidation stage of the production process.
  • This booster compressor can be either upstream of the oxidation reactor if the ICOCGT compressor discharges at a pressure lower than the oxidation reaction pressure, or downstream if the ICOCGT compressor discharges at a higher pressure than the oxidation reaction pressure.
  • solvent in the gaseous stream for example acetic acid in TA production
  • solvent in the gaseous stream for example acetic acid in TA production
  • separation apparatus such as a distillation column or overhead condensers.
  • pX paraxylene
  • the gaseous stream when it leaves the reactor, typically has a temperature from 150 to 220°C and a pressure from 600 kPa to 2500 kPa.
  • the temperature and pressure of the reactor can be selected to optimize the operation of the reactor and the downstream processes. Different temperatures apply for other processes.
  • the gaseous stream leaving the reactor is heated to at least 600°C with any suitable heater or combination of heaters.
  • suitable heater or combination of heaters might be a process heat exchanger heated by available hot utility source (such as steam or hot oil) or an available hot process stream, a direct heater of the gaseous stream (such as a combustor fuelled for example with natural gas or fuel oil), or an indirect heater of the gaseous stream (such as a furnace fuelled for example with natural gas or fuel oil).
  • fuel and oxidant for example from the reactor oxidant feed
  • a furnace heats the gaseous stream indirectly, i.e.
  • fuel and oxidant for example air
  • oxidant for example air
  • Indirect heating can be advantageous as it does not require additional oxidant to be fed above atmospheric pressure to the gaseous stream to burn the fuel.
  • indirect heating can involve combustion of fuel using atmospheric air.
  • auxiliary heaters can be used in addition to the heater for heating the gaseous stream.
  • the gaseous stream Prior to heating (i.e. upstream of the heater), the gaseous stream can be fed to a catalytic combustion unit (CCU). CCUs are typically used for environmental reasons to remove organic compounds and reactor byproducts in the gaseous stream and operate by flameless oxidation of the organic compounds etc. (e.g. MeBr).
  • the gaseous stream leaving the CCU has a temperature of from about 350°C to about 600°C.
  • the gaseous stream can be heated with an interchanger, i.e. a heat exchanger that transfers heat between a process stream and the gaseous stream.
  • the temperature of the gaseous stream entering the CCU can be about 250°C to about 400°C, for example about 300°C, to ensure stable combustion in the CCU.
  • the gaseous stream Prior to treatment with the CCU, can be heated from about 200°C to about 350°C, for example from about 300°C to about 350°C.
  • a steam heater provided upstream of the CCU can be used to achieve such heating.
  • the steam heater can use steam produced as a by-product of the oxidation reaction to heat the gaseous stream.
  • the gas can be treated, for example by scrubbing (for example by use of a scrubber), to remove reactive components such as HBr and Br 2 prior to feeding to a gas heater.
  • scrubbing for example by use of a scrubber
  • One way of heating the gaseous feed stream to the CCU can be to interchange heat with the CCU exit stream.
  • Air can also be added to the gaseous stream or the compressed air stream to increase the oxygen concentration of the mixed air / catalytically combusted gaseous stream to the combustion chamber of the ICOCGT or else added directly to the combustor.
  • the gaseous stream, immediately prior to entering the expander (stream 9) has a temperature of at least 600°C, including from about 600°C to 1400°C, from 600°C to about 1100°C, from 800°C to about 1100°C, 900°C, 950°C, 000°C, and 1050°C. Air can be added to the gaseous stream to
  • the mass flow of added air can be in the range of from about 0% to about 35% of the mass flow of the compressed air to the reactor, for example during normal operation about 20% , of the mass flow of the compressed air to the reactor.
  • Air compression is a costly step in the reaction process, therefore, this cost should be partially offset by power recovery from the gaseous stream.
  • the temperature of the compressed air stream can be excessively high to be fed directly to the oxidation reactor and can be used as a heating medium, for example, to displace the use of steam and thereby improving the overall energy efficiency of the production process.
  • the gas turbine used in the disclosed processes can be of a standard design and construction (as stated above) with only minor modifications.
  • the disclosed processes use a gas turbine designed for the temperatures, pressures, and flow rates of the gaseous stream, and that needed for compressing the air fed to the reactor.
  • an additional compressor or booster can be used before the compressed air inlet to the reactor or to increase the pressure of the gaseous stream.
  • Multiple gas turbines can be used in parallel to optimize the compressed air flow rates to match the PTA production plant capacity.
  • a heater indirect or direct can be provided to heat the air.
  • a "gas turbine” refers to a standard gas turbine, for example those described and listed in API 616 Gas Turbines for the Petroleum, Chemical and Gas Industry Services and Turbomachinery International Handbook 2006, vol. 46, no. 6, comprising a compressor coupled to an expander by one or more shafts.
  • the expander is connected to the gaseous stream downstream of the heater.
  • the compressor is connected to the oxidant inlet of the reactor and compresses the gaseous oxidant fed to the reactor.
  • the expander power generated will be greater than the compressor power consumption.
  • the gas turbine used in the invention can be of a standard design and construction with only minor modification.
  • the present invention selects a gas turbine designed for the temperatures, pressures and flow rates of the gaseous stream, and the power requirements of the compressor for compressing the oxidant feed.
  • An expander or booster compressor can be provided downstream of the gas turbine compressor on the gaseous oxidant feed. This expander or compressor allows adjustment of the gas turbine's compressor discharge to match the optimum pressure of gaseous oxidant into the reactor in order to assist with the integration of the gas turbine with the remaining components of the power recovery system and the reactor, and to allow optimisation of the power recovery.
  • This embodiment can be particularly advantageous, as it enables de-coupling of the requirements of the gas turbine and reactor, thereby allowing the reactor and gas turbine operations to be optimised independently.
  • a booster compressor can be located downstream of the oxidation reactor and upstream of the heater to adjust and optimise the pressure of the gaseous stream into the expander.
  • Gas for example steam or air
  • gas can be added to the gaseous stream, prior to, or simultaneously with, feeding the gaseous stream to the expander inlet.
  • gas can be added to the gaseous stream prior to feeding the gaseous stream to the expander inlet (i.e. upstream of the expander) and, therefore, in the power recovery system of the invention, the steam (or air) inlet is upstream of the expander.
  • This can be advantageous to match the compressor and expander duties, enabling the use of a standard gas turbine.
  • air can be added to the compressed air stream from the ICOCGT to provide the matching of compressor and expander duties. This arrangement reduces the amount of compressed air that needs to be extracted from the ICOCGT compressor and returned externally to the ICOCGT combustor.
  • An Internal Combustion Open Cycle Gas Turbine as disclosed in API 616 Gas Turbines for the Petroleum, Chemical and Gas Industry Services, comprises a compressor, a combustor and an expander and is optimized to generate power.
  • An embodiment of the present invention utilizes an ICOCGT to beneficially recover power from the gaseous stream produced by an oxidation reaction.
  • the compressor stage of the ICOCGT compresses the oxidant feed to the reactor (at greater than atmospheric pressure) thereby at least partially offsetting the cost of providing the high temperature and pressure reaction conditions in the reactor.
  • the expander stage of the ICOCGT expands the heated gaseous stream from the oxidation reactor recovering energy to power the compressor and a hot gas stream, for example to raise steam downstream of the ICOCGT.
  • the net power generated can be used to offset the power requirement of the PTA plant. Surplus power can be exported from the plant.
  • the reactor is a continuous flow reactor, meaning a reactor in which reactants are introduced and mixed and products withdrawn simultaneously in a continuous manner, as opposed to a batch-type reactor.
  • a standard oxidation reactor for example as disclosed in US 7,153,480, can be used.
  • Standard reactants and operating conditions for example as disclosed in US 7,153,480, can also be used.
  • the oxidant in the invention can be molecular oxygen, for example air (including oxygen-depleted air and oxygen enriched air).
  • Oxidation reactions are typically exothermic and heat can be removed, in order to control the reaction temperature, by removing the volatile components, condensing them, and returning the condensate to the reactor.
  • the heat of reaction can be removed from the reaction by heat exchange with a heat-accepting fluid, according to conventional techniques known to those skilled in the art.
  • the reactor is generally operated in a continuous mode. By carrying out the process in a continuous flow reactor, the residence time for the reaction can be made compatible with the attainment of conversion of the precursors to the desired product without significant production of degradation products.
  • the gaseous stream can be heated to a temperature to at least 600°C, including from about 600°C to 1400°C, from 600°C to about 1 100°C, from 800°C to about 1100°C, 900°C, 950°C, 1000°C, and 1050°C
  • reference to the production of a carboxylic acid includes reference to the production of its ester. As will be evident to the skilled person, whether a carboxylic acid or its ester is produced will depend on the conditions in the reactor and/or the conditions used to purify the products.
  • aromatic carboxylic acid precursor or “precursor” means an organic compound, preferably a hydrocarbon, capable of being oxidised to a specific aromatic carboxylic acid in a majority yield in the presence of selective oxidising conditions.
  • aromatic carboxylic acid precursor is paraxylene.
  • isophthalic acid precursor is metaxylene.
  • the disclosed processes can comprise feeding solvent, oxidant, precursor and catalyst into an oxidation reactor that is maintained at a temperature in the range of from about 150°C to about 250°C, for example about 175°C to about 225°C, and a pressure in the range of from about 100 kPa to about 5000 kPa, for example about 1000 kPa to about 3000 kPa.
  • the oxidation reaction can be carried out in the presence of an oxidation catalyst.
  • the catalyst can be substantially soluble in the reaction medium comprising solvent and the aromatic carboxylic acid precursor(s).
  • the catalyst can comprise one or more heavy metal compounds, for example cobalt and/or manganese
  • the catalyst can take any of the forms that have been used in the liquid phase oxidation of aromatic carboxylic acid precursors such as terephthalic acid precursor(s) in aliphatic aromatic carboxylic acid solvent, for example bromides, bromoalkanoates or alkanoates (usually C-1-C4 alkanoates such as acetates) of cobalt and/or manganese.
  • aromatic carboxylic acid precursors such as terephthalic acid precursor(s) in aliphatic aromatic carboxylic acid solvent
  • bromides, bromoalkanoates or alkanoates (usually C-1-C4 alkanoates such as acetates) of cobalt and/or manganese for example bromides, bromoalkanoates or alkanoates (usually C-1-C4 alkanoates such as acetates) of cobalt and/or manganese.
  • Compounds of other heavy metals such as vanadium, chromium, iron, molybdenum, a
  • the catalyst system can include manganese bromide (MnBr 2 ) and/or cobalt bromide (CoBr 2 ).
  • the oxidation promoter where employed, can be in the form of elemental bromine, ionic bromide (for example HBr, NaBr, KBr, NH4Br) and/or organic bromide (for example bromobenzenes, benzyl-bromide, mono- and di-bromoacetic acid, bromoacetyl bromide, tetrabromoethane, ethylene-di-bromide, etc.).
  • ionic bromide for example HBr, NaBr, KBr, NH4Br
  • organic bromide for example bromobenzenes, benzyl-bromide, mono- and di-bromoacetic acid, bromoacetyl bromide, tetrabromoethane, ethylene-di-bromide,
  • any suitable solvent in which the oxidation reaction can take place can be used.
  • the solvent can be an aliphatic monocarboxylic acid having from 2 to 6 carbon atoms, for example, the solvent can be acetic acid.
  • Acetic acid can be particularly useful as the solvent since it is relatively resistant to oxidation in comparison with other solvents and increases the activity of the catalytic pathway.
  • the reaction can be effected by heating and pressurising the precursor, catalyst and solvent mixture followed by introduction of the oxidant into the reactor via the oxidant inlet.
  • the effluent, i.e. reaction product, from the oxidation reactor can be a slurry of aromatic carboxylic acid crystals which are recovered from the slurry by filtration and subsequent washing.
  • the main impurity in crude TPA is 4-carboxybenzaldehyde (4-CBA), which is incompletely oxidized paraxylene, although other oxidation products and precursors to terephthalic acid such as p-tolualdehyde and p-toluic acid can also be present as contaminants.
  • 4-CBA 4-carboxybenzaldehyde
  • FIG. 2 Disclosed in Figure 2 is one aspect of a process for maintaining the operation of a TA oxidation plant during a process interruption.
  • the compressed air stream is isolated from the oxidation reactor and diverted directly to the combustion chamber and then fed to the gas turbine expander.
  • the catalytic combustor can also optionally be isolated in this scenario.
  • the compressed air stream can flow through the catalytic combustor to the combustion chamber, followed by an optional and a small flow or no make-up air flow to the combustion chamber. This change separates the operation of the oxidation reactor and the gas turbine.
  • the gas turbine continues to operate, producing steam in the steam generator, enabling other stages of the process to continue in operation.
  • controlling the operation of the ICOCGT increases output of high grade heat, such as high pressure steam from the steam generator.
  • high grade heat such as high pressure steam from the steam generator.
  • This increase is achieved by retaining oxygen in the ICOCGT sufficient to sustain combustion and feeding the vent gas stream (still containing the oxygen not consumed in the oxidation reactor) from the expander to an auxiliary combustor together with more fuel.
  • the increased heat output in the absence of heat from the oxidation reactor, can be designed to be sufficient to keep the terephthalic acid purification stage in routine operation, start-up the oxidation stage of the process after a process interruption and supply other process uses, thereby eliminating the need for other sources of high grade heat, such as high pressure steam.
  • With high pressure steam as the steam generator operates continuously when the oxidation stage of the production process is in operation, its change of duty to generate steam when the oxidation reactor operation is interrupted can be handled very rapidly, enabling the reset of the production stages to remain in routine operation.
  • the heat recovery system can be a heat exchanger or a combustor feed interchanger.
  • the power recovery system comprises an expander that drives a compressor.
  • the expander can drive the compressor via a shaft that couples the two together.
  • the system that utilizes the expander vent gas can be employed in situations where process interruptions occur.
  • the heat recovered from the heated vent stream is sufficient enough to generate high pressure steam or hot oil for use in the terephthalic acid purification stage, the paraxylene - air oxidation stage, start-up, re-starting of the process, or a combination. Examples
  • Table 1 (below) assumes the use of high pressure (“HP") steam and shows the relative mass flows, compared to the normal generation of high pressure steam, for the two modes of operation.
  • HP high pressure
  • ambient air is compressed and heated to about 365°C before flowing to the combustor feed interchanger, where it is cooled, before feeding to the oxidation reactor.
  • the gaseous stream vented from the oxidation reactor flows to a condenser to remove condensables, before the gaseous stream temperature is increased in the combustor feed interchanger and heater.
  • the heated gaseous stream flows to the catalytic combustor, where volatile organics and other gaseous components are combusted.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention concerne un procédé et un système permettant de récupérer de la puissance à partir d'un flux gazeux produit par une réaction d'oxydation paraxylène/air. Plus particulièrement, l'invention repose sur le chauffage du flux gazeux provenant de la réaction d'oxydation à une température d'au moins 600°C, la récupération de l'énergie par le biais d'un détendeur, le chauffage du flux provenant de l'orifice d'aération du détendeur et la récupération de la chaleur provenant du flux de l'orifice d'aération. La chaleur récupérée est utilisée pour assurer le maintien du procédé d'oxydation et du procédé de purification et pour démarrer ou redémarrer le procédé après une interruption.
PCT/US2014/038546 2013-05-24 2014-05-19 Récupération de puissance destinée à être utilisée dans le démarrage ou le redémarrage d'un procédé de production d'acide téréphtalique pur WO2014189818A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US13/901,666 2013-05-24
US13/901,666 US20130255259A1 (en) 2008-10-24 2013-05-24 Power recovery for use in start-up or re-start of a pure terephthalic acid production process

Publications (1)

Publication Number Publication Date
WO2014189818A1 true WO2014189818A1 (fr) 2014-11-27

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PCT/US2014/038546 WO2014189818A1 (fr) 2013-05-24 2014-05-19 Récupération de puissance destinée à être utilisée dans le démarrage ou le redémarrage d'un procédé de production d'acide téréphtalique pur

Country Status (2)

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TW (1) TW201512165A (fr)
WO (1) WO2014189818A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131920B1 (fr) * 1983-07-18 1991-04-03 Air Products And Chemicals, Inc. Expansion contrôlée de la température dans la préparation d'oxygène au moyen de sels fondus de métaux alcalins
EP0301844B1 (fr) * 1987-07-29 1993-06-09 Btg International Limited Procédés chimiques à réaction exotherme
EP0513186B1 (fr) * 1990-01-31 1997-07-30 Modar, Inc. Procede d'oxydation de matieres dans l'eau a des temperatures supercritiques
US7622033B1 (en) * 2006-07-12 2009-11-24 Uop Llc Residual oil coking scheme
EP2495405A2 (fr) * 2008-05-06 2012-09-05 Invista Technologies S.à.r.l. Récupération d'énergie

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131920B1 (fr) * 1983-07-18 1991-04-03 Air Products And Chemicals, Inc. Expansion contrôlée de la température dans la préparation d'oxygène au moyen de sels fondus de métaux alcalins
EP0301844B1 (fr) * 1987-07-29 1993-06-09 Btg International Limited Procédés chimiques à réaction exotherme
EP0513186B1 (fr) * 1990-01-31 1997-07-30 Modar, Inc. Procede d'oxydation de matieres dans l'eau a des temperatures supercritiques
US7622033B1 (en) * 2006-07-12 2009-11-24 Uop Llc Residual oil coking scheme
EP2495405A2 (fr) * 2008-05-06 2012-09-05 Invista Technologies S.à.r.l. Récupération d'énergie

Also Published As

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