TWI359132B - Improved recovery of energy during the production - Google Patents

Description

Nine, invention description: t Ming technology ^ ig " collar 3 The invention relates to improved energy recovery technology during the manufacture of aromatic acid retardants. C Prior Art 发明 Background of the Invention For many chemicals and polymer products, aromatic acid retardants such as benzoic acid, phthalic acid, terephthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid , trimesic acid and naphthalene dicarboxylic acid are important intermediates. The aromatic acid can be produced by liquid phase oxidation of a suitable aromatic hydrocarbon feed. For example, U.S. Patent No. 2,833,816, the disclosure of which is incorporated herein by reference in its entirety, the disclosure of the entire disclosure of the entire disclosure of the disclosure of the entire disclosure of the disclosure of the disclosure of the entire disclosure of the disclosure of the entire disclosure of the disclosure of the entire disclosure of the disclosure of the entire disclosure of acid. Another example is the disclosure of the liquid phase oxidation of dimethylnaphthalene to form naphthalenedicarboxylic acid in the liquid phase of the formation of naphthalene dicarboxylic acid in the U.S. Patent No. 5,1,3,933, the disclosure of which is incorporated herein by reference. It is completed in the presence of a catalyst containing manganese. The aromatic carboxylic acid is typically purified in a subsequent process, including contacting in a reducing environment to contact the crude aromatic carboxylic acid with a catalyst and hydrogen, as described in the following patents: U.S. Patent No. 3,584, 〇39 No. 4,892,972 and U.S. Patent No. 5,362,900. The liquid phase oxidation of an aromatic hydrocarbon to form an aromatic carboxylic acid is carried out using a reaction mixture containing an aromatic hydrocarbon and a solvent. This solvent typically comprises a CVC8 monocarboxylic acid, such as acetic acid or benzoic acid, or a mixture thereof with water. By 'aromatic hydrocarbon', it is meant a molecule of 1359132 consisting of a carbon atom and a hydrogen atom, and having one or more aromatic rings, such as a benzene ring or a naphthalene ring. For the purposes of this application, "aromatic hydrocarbons" "includes a molecule having one or more heteroatoms such as oxygen or nitrogen. An aromatic hydrocarbon suitable for liquid phase oxidation to form an aromatic carboxylic acid typically comprises a 5-aromatic hydrocarbon having at least one substituent which can be oxidized to a carboxylic acid, For example, alkyl aromatic hydrocarbons such as dimethylbenzene and dimethylnaphthalene. As used herein, "aromatic carboxylic acid" means an aromatic hydrocarbon having at least one carboxylic acid group. A catalyst is also present in the oxidation reaction mixture. The catalyst contains an accelerator, for example, and at least one suitable heavy metal component. Suitable heavy metals include heavy metals having an atomic weight ranging from about 23 to about 178. Example 10 includes knot, lanthanum, cerium, indium, chromium, iron, nickel. , wrong, decorative or lanthanide metals such as bells. Suitable forms of these metals include, for example, acetates, hydroxides and carbonates. A source of molecular oxygen is also introduced into the reactor t. Usually, the oxygen system Used as a source of molecular oxygen, and mixed in a liquid phase reaction mixture by means of a bubble or other means. 15. Air is usually used to supply oxygen. Subsequent purification processes usually involve reducing the aromatic aromatic carboxylic acid under reducing conditions. The solution of the oxidation reaction product is contacted with hydrogen and a catalyst. The catalyst used for this purification typically contains one or more active hydrogenation metals such as ruthenium, linkages, palladium on a suitable support such as carbon or titanium dioxide. There are a number of variations and improvements in the liquid phase oxidation process. For example, U.S. Patent No. 6,194,607 to Jhung et al. discloses the use of an alkali or alkaline earth in the oxidation of diterpenic benzene isomers to phthalic acid. The metal is added to the reaction mixture; the addition of ruthenium to the oxidation catalyst is disclosed in U.S. Patent No. 5,112,992 issued to Belmonte et al.

The adjustment of the acetic acid concentration to control the oxidation rate is disclosed in U.S. Patent No. 5,81,290 to Partenheimer et al. The oxidation reaction in the liquid phase oxidation reaction of cigarettes is an exothermic reaction. The heat of reaction is usually removed by boiling the liquid reaction mixture. As a result, a gas phase is formed above the liquid in the reactor. This gas phase usually contains a large amount of a reaction solvent. The column gas is typically removed from the reactor to control the exotherm of the reaction. However, such removal of the overhead gas represents a significant loss of solvent. Significant loss of solvent is disadvantageous and it is advantageous to recover the solute from the gas phase. The removed overhead gas can be at least partially condensed and recycled to the reactor as condensate or used elsewhere in the process, downstream process steps or integrated operations. The overhead gas removed from the oxidation reaction is usually under high pressure, and the energy recovery from the gas phase of the phase-containing U-autolysis reactor will significantly reduce the total energy of the aromatics. The demand for global energy increases. As the demand for special aromatics has also increased, this important collection of energy recovery has continued to increase, and environmental and legislative changes to many energy production methods have increased the importance of shouting process energy. Efforts have been made to recover energy from the high-pressure overhead vapor, using the gas stream to exchange (iv) (iv) heat (s) steam. In this condensation operation, all the water or substantially all of the gas entering the condenser The water is condensed into a liquid state. U.S. Patent Nos. 5'723,656 and 5,612, 〇〇7 to Abrams (incorporated herein by reference), the portion of the basin is exposed - liquid reduction 24, The oxidation reaction overhead gas 1359132 is introduced into a high pressure, high efficiency separation unit to remove at least 95% by weight of the solvent from the oxidation reaction overhead gas and form a high pressure overhead gas stream which is directed An energy recovery device is disclosed in U.S. Patent No. 6,504,051, the entire disclosure of which is incorporated herein by reference. Wherein the oxidation reaction overhead gas is directed to a water removal column from which an overhead gas stream containing deoxygenated waste gas, water and a small amount of solvent and reaction by-products is obtained. Miller et al. disclose separation of the overhead gas stream The first portion can be led to a first portion of an energy recovery device 10 and a second portion that is directed to a condenser. The condensable components are returned from the condenser to the water removal column, and the remaining gas can be directed to Energy recovery unit.

The energy recovery maps disclosed by Abrams and Miller et al. can recover large amounts of energy from the high pressure overhead gas stream. However, there is still a large amount of energy in the high pressure overhead gas stream that is not utilized. In the past, attempts to recover energy by condensing all or a portion of the high pressure overhead stream were based on complete condensation. Other attempts have been to expand the uncondensed or non-condensable gas stream from the complete condensate stream to recover energy. As the overall energy demand increases, the demand for specific aromatic carboxylic acids increases, and the environment for energy production methods and 20 legislative restrictions increase, the importance of recycling at least some of this unused energy is also increased. . Therefore, there is a need for an improved process for recovering energy from the generated overhead gas during the liquid phase oxidation reaction of aromatic hydrocarbons to form aromatic carboxylic acids. [Abstract] Summary of the Invention We have discovered that in aromatic hydrocarbons During the liquid phase oxidation reaction to form an aromatic carboxylic acid, partial condensation is used, and then the energy is recovered into a "work" form, 5 which can recover a surprising amount of energy from the high pressure overhead gas stream formed by the overhead vapor of the reaction column, preferably An isentropic energy recovery method is used, and an expander is more preferably used. Unlike the previous energy recovery method that extracts thermal energy by means of substantially complete condensation, partial condensation of the high pressure overhead gas stream can achieve significant heat recovery, while still retaining considerable energy in the high pressure exhaust gas leaving the condenser, which 10 Some energy can be recycled into the form of “work”. This combination of thermal energy extraction and "work" extraction energy recovery advantageously employs each energy recovery method at its appropriate point. In one embodiment, the present invention is an energy recovery method during the formation of an aromatic carboxylic acid by an aromatic hydrocarbon via a liquid phase oxidation reaction in which a reaction overhead vapor containing a reaction solvent and water is formed. The method comprises the steps of: efficiently separating the overhead vapor of the reaction to form a high pressure overhead gas stream comprising water and an organic solvent; recovering thermal energy from the high pressure overhead gas stream by heat exchange with a suitable heat dissipating material Forming a condensate and a high pressure exhaust gas containing from about 20% by weight to about 60% by weight of water present in the high pressure overhead gas stream; and recovering energy from the high pressure exhaust gas into a "work" form . The present method may optionally further comprise the step of subjecting the high pressure exhaust gas to a thermal oxidation reaction to oxidize at least a portion of the organic impurities prior to recovering the energy from the high pressure exhaust gas to a "work" form. Preferably, such thermal oxidation reaction is a catalytic reaction. Recycling from high pressure exhaust gas

9 1359132 The step of energy becoming a form of "work" preferably includes directing at least a portion of the high pressure exhaust gas to an expander. The step of recovering energy from the high-pressure exhaust gas into a "work" form is preferably carried out by an isentropic energy recovery method, more preferably using an expander. In another embodiment, the invention provides a method for making an aromatic carboxylic acid. The process comprises the steps of: in a reaction zone containing at least one reactor, in the presence of a catalyst and a dentate promoter, in a reaction solvent containing a CkCs monocarboxylic acid, and at about 120 ° C Oxidizing the aromatic hydrocarbons to form an aromatic tetacid with a oxidizing gas in a liquid phase condition to a temperature range of about 250 ° C. The catalyst contains at least one heavy metal having an atomic weight of from about 23 to about 178 to form an aromatic rebellion. An acid product and a reaction overhead vapor containing water and solvent vapor; a high efficiency separation of the reaction overhead vapor to form a bottom liquid stream and a high pressure overhead gas stream, the bottom liquid stream containing the reaction column At least 95% by weight of the solvent of the overhead vapor, the high pressure overhead gas 15 stream containing at least 50% by weight of water from the overhead vapor of the reaction; heat exchange with a high pressure overhead gas stream with a suitable heat dissipating material to Recycling into heat to form a condensate and a high pressure exhaust gas containing from about 20% to about 60% by weight of water in the high pressure overhead gas stream; and energy from the high pressure exhaust gas Harvest in the form of "work". 20 The method may optionally include the step of returning all or a portion of the bottoms stream to the reaction zone. Preferably, the step of recovering energy into a "work" form includes introducing at least a portion of the high pressure exhaust gas to an expander. Preferably, the step of recovering energy from the high pressure exhaust gas into a "work" form employs an isentropic energy recovery means, more preferably an expander.

10 1359132 In another embodiment, the present invention provides an apparatus for efficiently recovering energy in an overhead vapor formed during the manufacture of a fragrance carboxylic acid by an aromatic hydrocarbon via a liquid phase oxidation reaction. The apparatus comprises a reactor. , having a venting opening for discharging the reaction overhead vapor; a high efficiency separating device in fluid communication with the counter reactor, having at least one gas inlet for receiving the reaction overhead vapor from the reactor, at least one liquid An inlet for receiving a liquid in reverse contact with the vapor of the reaction overhead, at least one liquid outlet for removing the liquid, and at least one gas outlet for removing the high pressure overhead gas stream; a condenser being in fluid communication with the high efficiency separation device The condenser is adapted to extract energy from the high pressure overhead gas stream by partially condensing at least one portion of the high pressure overhead gas stream and heat exchange with a heat dissipating material; and an expander in fluid communication with the condenser And having at least one inlet for receiving the exhaust gas containing water, and at least one outlet for discharging the exhaust gas having a lower pressure than the exhaust gas. The high efficiency separation unit can be one or more high efficiency distillation columns. Preferably, condenser 15 is adapted to condense from about 20% to about 60% by weight of water present in the high pressure overhead gas stream. Preferably, the apparatus further comprises a thermal oxidation unit in fluid communication with the condenser and the expander. Optionally, the condenser is adapted to return the condensed liquid from the condenser to the high efficiency separation unit. BRIEF DESCRIPTION OF THE DRAWINGS 20 FIG. 1 is a flowchart of a method representative of an embodiment of the present invention. Figure 2 represents a prior art scheme for recovering energy during liquid phase oxidation of aromatic hydrocarbons to form aromatic carboxylic acids. Figure 3 is a graph representing energy recovery based on two existing schemes compared to energy recovery in accordance with an embodiment of the present invention. 11 1359132 [Solid package method 3 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention provides an improved method and apparatus for use in a reactor overhead vapor produced from the liquid phase oxidation reaction of aromatic hydrocarbons to produce aromatic carboxylic acids. 5 Recover energy. The energy is recovered from a high pressure overhead gas stream which is obtained by performing a highly efficient separation of the reactor overhead vapor. The energy is recovered into the form of thermal energy and the form of "work". The combination of these two forms of energy recovery results in a greater total energy recovery. The water present in the high pressure overhead gas stream represents a significant source of energy 10 . We have found that extracting energy from water into a form of heat and a form of "work" is a form of heat that is mainly a form of heat or a form of "work" that can result in significantly greater total energy recovery. When the high pressure overhead gas stream is at its highest temperature, it is most efficient to extract energy from the gas stream. As the airflow cools, the extraction of thermal energy becomes less efficient than the way in which the extracted energy becomes "work". This energy recovery combined with the extraction of thermal energy and "work" advantageously employs each energy recovery method at its appropriate point. Surprisingly, with this combination, significantly more energy is recovered. In one embodiment, 20 energy is recovered as heat from the high pressure overhead gas stream by condensing only a portion of the water present, and by expanding a gas stream containing uncondensed water. And the energy recovery is "work". As used herein, "condensing" refers to water, together with other species that condense under similar conditions, condense into a stream. As used herein, "completely condensing" means that more than 90% by weight of the water in the gas 12 1359132 stream is condensed. The "heat" is extracted by partial condensation of the high pressure overhead gas stream and the "work" is extracted from the uncondensed portion of the high pressure overhead gas stream. The energy recovery obtained by the combination of the two is significantly higher than that obtained from the industrial examples. Energy recovery, a conventional technique for recovering energy from an aqueous high pressure overhead stream using expansion without condensation, or a conventional technique for energy recovery using a combination of complete condensation and expansion. The energy recovery that can be provided by the method and apparatus of the present invention will now be described in more detail. The reaction of the liquid phase oxidation of aromatic hydrocarbons to aromatic decanoic acid can be carried out by a batch process, a continuous process or a semi-continuous process. A reaction mixture is formed by combining an aromatic hydrocarbon feedstock, a solvent, and a catalyst having a promoter (usually bromine). In a continuous or semi-continuous process, the components of the reaction mixture are preferably combined in a mixing flask prior to being introduced into the reaction zone, but the reaction mixture 15 can also be formed in the reaction zone. Aromatic carboxylic acids suitable for use in the process of the present invention include monocarboxy and polycarboxy species having one or more aromatic rings which can be produced by the reaction of a gas phase with a liquid phase reactant in a liquid phase system. Examples of aromatic carboxylic acids which are particularly suitable for use in the present invention include terephthalic acid, succinic acid, trimellitic acid, 20 phthalic acid, isomeric acid, benzoic acid and naphthalene dicarboxylic acid. Suitable fragrant raw materials generally comprise an aromatic hydrocarbon having at least one group which can be oxidized to a carboxylic acid group. The substituent which may be oxidized may be an alkyl group such as a mercapto group, an ethyl group or an isopropyl group. It may also be a group which originally contains oxygen, such as a burnt group, a mercapto group or a ketone group. The substituents may be the same or different. original

The aromatic moiety of the 13 compound may be a benzene nucleus or may be a bicyclic or polycyclic ring such as a naphthalene nucleus. The number of oxidizable substituents on the aromatic portion of the starting compound may be equal to the number of positions taken by the aromatic month b but is usually less than the total number of these positions, preferably from 1 to about 4, and more preferably 1 To 3. Examples of useful compounds include oxime, ethylbenzene, o-xylene, p-nonylbenzene, m-nonylbenzene, 1-hydrazino-4-methylbenzene, 1-hydroxyindole-4-indole Benzobenzene, anthracene, 2'4-dimethylbenzene, U-mercapto-2,4-dimethylbenzene, 1,2,4,5-tetradecyl-styl-yl-methylmethyl-methyl- And fluorenyl-substituted naphthalene compounds, such as 2'6- and 2'7-monomethylcaxene, 2-branched- 6 methyl-Cai, 2-branched- 6-methylnaphthalene' 2_methyl_6· Ethyl-Cate and 2,6-diethylnaphthalene, anthracene-substituted, phenyl-substituted phthalene-substituted naphthalene's benzoic acid, methyl acetophenone, decyl benzyl alcohol, and succinct compounds Partially oxidized intermediates and any combination thereof. An aromatic carboxylic acid is produced by an oxidation reaction of a corresponding aromatic hydrocarbon precursor, for example, from the para-substituted silly to produce terephthalic acid, or from a disubstituted Cai to produce a naphthalenedicarboxylic acid, preferably Preferably, the content of the precursor corresponding to the desired acid in the raw material used is at least about 95% by weight, and more preferably at least 98% by weight or more, using a relatively pure raw material. A preferred aromatic hydrocarbon feedstock for the manufacture of terephthalic acid comprises p-nonylbenzene. It is a preferred raw material for the manufacture of benzoic acid. It is preferred to contain a liquid acid such as a benzoic acid, especially a lower alkyl group (e.g., crc 8), a monocarboxylic acid such as acetic acid, because they are not easily used under typical oxidation reaction conditions for producing aromatic carboxylic acids. The oxidation reaction is carried out to increase the efficiency of the catalyst in the oxidation reaction. Specific examples of suitable carboxylic acids include acetic acid, propionic acid, butyric acid, benzoic acid, and mixtures thereof. Ethanol and other cosolvent materials which oxidize to monocarboxylic acids under typical oxidation conditions of 1359132 can be used directly or in combination with carboxylic acids with good results. Of course, for the efficiency of the overall process and to minimize the separation, when a solvent containing a mixture of a monocarboxylic acid and such a cosolvent is used, it is preferred that the 5 cosolvent should be oxidized to the monocarboxylic acid used therewith. acid. The catalyst used in accordance with the present invention contains a material which is effective in catalyzing the oxidation reaction of an aromatic hydrocarbon material to form a fragrant acid. Preferably, the catalyst is dissolved in the liquid oxidation reaction mixture to promote contact between the catalyst, oxygen and liquid feed; however, non-homogeneous catalysts or catalysts may also be used. Typically, the catalyst contains a bromine promoter and at least one suitable heavy metal component such as a metal having an atomic weight of from about 23 to about 178. Examples of suitable heavy metals include start, manganese, vanadium, turn, chromium, iron, nickel, erbium, ruthenium or a lanthanide metal such as a feed. Suitable forms of these metals include, for example, acetates, hydroxides, and carbonates. The catalyst preferably contains only the cobalt compound, or 15 or one or more of the following compounds: a manganese compound, a ruthenium compound, a chelate compound or a compound. Generally, an accelerator is used to increase the oxidation activity of the catalyst metal, preferably without producing undesirable by-products' and preferably in a form soluble in the liquid phase reaction mixture. The dentate compound is often used as a 20-accelerator, such as a functional hydrogen, a sodium hydride, a potassium halide, a functional ammonium, a halogen-substituted hydrocarbon, an i-substituted carboxylic acid, and other compounds. Preferably, a bromine compound is used as a promoter. Suitable bromine promoters include molybdenum, Bi:2, HBr, NaBr, KBr, NH4Br, benzyl bromide, bromoacetic acid, dibromoacetic acid, tetrabromoethane, dibromoethane, ethidium bromide or mixture.

15 1359132 5 10 15 20 The oxidation reaction is carried out in the reaction zone. The reaction zone typically contains one or more reactors. The appropriate oxidation reactor is constructed to withstand high pressure and high temperature conditions and is resistant to the presence of corrosive liquids and gas phase components present in the reaction zone. The reaction zone allows the addition of catalysts, liquid and gaseous reactants and solvent systems. And mixing therein, the aromatic carboxylic acid product or the liquid containing the product for recovery can be removed, and the high pressure vapor generated by the liquid phase oxidation reaction can be removed to control the heat of the reaction. Types of reactors that may be used include, but are not limited to, continuous stirred tank reactors and plug flow reactors. Typically, the oxidation reactor comprises a cylindrical vial, typically having a central axis that extends vertically when the reactor has been positioned for use in the process, having - or a plurality of mixing features to disperse oxygen in one The liquid phase is boiled in the reaction mixture. Typically, the hybrid feature includes - or a plurality of impellers mounted on a rotating shaft or a shaft that is otherwise moved. For example, the impeller can extend from a central vertical axis of rotation. The reactor can be constructed of materials designed to withstand specific temperatures, pressures, and reactive compounds used. In summary, suitable oxidation reactors are constructed of inert, corrosion-resistant materials such as titanium, or may be lined with materials such as bristles or glass to improve corrosion resistance and other adverse effects. For example, 'titanium and broken glass, or other suitable anti-corrosion materials are used as reaction II and some other process equipment - solvent to produce p-dicarboxylic acid under typical reaction conditions, the solvent contains Acetic acid and - including catalyst systems with desert promoters, because acid solvents and certain reaction products such as methyl bromide are corrosive. A source of molecular oxygen is also introduced into the reaction zone. Typically, an oxidizing gas system is used as a gaseous source of molecular oxygen. Air can be conveniently used

16 1359132 As a source of molecular oxygen. Oxygen-enriched air, pure oxygen, and other gaseous mixtures containing molecular oxygen (usually at least about 5% by volume) can also be used. It can be appreciated that the demand for the compressor and the need to treat the inert gas in the reactor off-gas are reduced when the molecular oxygen content of the source is increased. The molecular oxygen source can be introduced into one or more of the reaction zones and is typically introduced in a manner that enhances contact between the molecular oxygen and other reactive compounds. Usually, the oxidizing gas system is introduced into the lower portion of the oxidation reactor and dispersed by a mixing device such as ~ or a plurality of impellers mounted on a rotating shaft. The molecular oxygen content of the oxidizing gas can vary, but is typically between about 5 and 1 〇〇 10 vol% molecular oxygen. To avoid the formation of potentially explosive mixtures, the addition of oxidizing gases typically results in unreacted oxygen in the vapor phase above the liquid reaction mixture in the reaction zone being below the flammability limit. The oxygen content of the vapor phase can be kept below the flammability limit by adjusting the mode and rate of oxygen introduction, the rate of reaction (which is affected by the reaction conditions), and the recovery of the exhaust gas. The amount of oxygen supplied is related to these operating parameters such that the vapor phase above the reaction mixture contains from about 0.5 to about 8 volume percent oxygen (measured on a solvent free basis). The ratio of starting materials, catalysts, oxygen, and solvent is not critical to the present invention' and varies with the choice of feed and target product, as well as the choice of process equipment and operating parameters. The weight ratio of solvent to feed is suitably from about 1:1 to about 30:1. The oxidizing gas is usually used in an amount of at least a stoichiometric amount based on the raw material, but does not cause the unreacted oxygen in the vapor phase above the reaction liquid to exceed the flammability limit. The use of the catalyst, based on the concentration of the catalyst metal (based on the aromatic hydrocarbon feed and solvent weight 1 of 17 1359132), is preferably greater than about 500 ppmw, and less than about 10,000 ppmw, and preferably less than about 6, 〇〇〇ppmw, more preferably less than about 3000 ppmw, is more suitable. Preferably, a halogen promoter, more preferably bromine, is present in an amount such that the atomic ratio of halogen to catalyst metal is suitably greater than about 0.1:1, preferably greater than about 0.2:1, and Suitably below about 4:1, preferably below about 3:1. The atomic ratio of halogen to catalyst metal is preferably from about 0.25:1 to about 2:1. The oxidation of the fragrant raw material to form a reaction system containing an aromatic acid retardation product is carried out under the oxidation reaction conditions. The reaction is carried out at a temperature sufficient to drive the oxidation reaction, to provide the desired purity, and to limit the combustion of the solvent. The heat generated by the oxidation reaction is dissipated to maintain the reaction conditions. Typically, the heat of reaction is removed from the reaction zone by boiling the reaction mixture and vaporizing the boiling. Generally, the 'suitable temperature is more than 12 (rc, preferably more than _ C, and less than about 250 ° C, preferably less than about 23 { rc. Many aromatic 15 carboxylic acids, such as for stupi dicarboxylic acid, Benzoic acid and naphthalene dinuclear, the manufacturing process. The reaction temperature is usually between about 145t and about 23 (rc. When the temperature is lower than about 12 〇, the oxidation reaction will proceed slowly, resulting in insufficient purity of the product, and conversion The rate is undesirably low. For example, less than about 12 Torr. At the temperature of 〇, the reaction of p-xylene to oxidize to stupid acid may take more than 24 hours to proceed to completion. The resulting p-dicarboxylic acid product, Because of its high impurity content, significant additional processing may be required. At temperatures above 25 〇 0 (:, significant solvent loss occurs due to solvent combustion. The magnitude of the pressure at which the oxidation reaction is carried out, at least W is maintained in the reactor Liquid phase, containing feed and solvent. Usually, about 5iU〇kg/cm2 gauge pressure

18 1359132 The preferred pressure for a particular 'specific process' varies with feed and solvent composition, temperature and other factors, but is usually between about 10 and about 3 〇 kg/cm2. The residence time in the reaction zone can be appropriately changed depending on the set productivity and conditions, and is approximately suitable for a plurality of processes from about 2 Torr to about 15 minutes. For the process in which the aromatic acid product is substantially dissolved in the reaction solvent, for example, in the process of producing trimellitic acid by oxidation reaction of diphenylbenzene (pseudo-pure phuedocumene) in an acetic acid solvent, the solid concentration in the liquid is Ignored. In other processes, such as the oxidation of diphenylene, the use of acetic acid and water as a solvent for the reaction mixture produces terephthalic acid or isophthalic acid, wherein the solids content can be as high as about 50 weights of the liquid reactant. %, usually at a concentration of from about 10 to about 35% by weight. As will be appreciated by those skilled in the art of aromatic acid manufacture, the preferred conditions and operating parameters will vary with the process of the product and may vary within the scope or even exceed the range. The aromatic carboxylic acid reaction product dissolved or slurried in a portion of the liquid phase reaction mixture from the liquid phase oxidation reaction can be treated by conventional techniques to recover the aromatic carboxylic acid reaction product contained therein. . Typically, the aromatic carboxylic acid products and by-products which are slurried, dissolved or slurried in the liquid reaction mixture and which are dissolved are removed and recovered from the reaction zone by suitable techniques. Therefore, in addition to the oxidation reaction step, the liquid phase oxidation reaction may comprise the step of recovering a product containing an aromatic carboxylic acid and impurities including reaction by-products from a liquid phase oxidation reaction mixture. The product soluble in the liquid can be recovered by crystallization, which is usually achieved by cooling or depressurizing the liquid slurry from the oxidation reaction zone. Forming a solid product in the form of a slurry, and from the reaction solution or from the crystallization solution

The solid precipitated by V 19 is conveniently separated by centrifugation, over-treatment or a combination of centrifugation and extinction. The solid product recovered from the reaction liquid by this technique contains an aromatic carboxylic acid and an impurity, which contains a by-product of the aromatic raw material. The liquid remaining after recovering the solid product from the liquid reaction mixture is generally called an oxidizing mother liquid 'comprising Solvent monocarboxylic acids, water, catalysts and promoters, soluble by-products of liquid phase oxidation reactions and impurities which may be present, for example from impurities in the recycle stream. The oxidizing mother liquor usually also contains a small amount of aromatic carboxylic acid, and the partial oxidation product or intermediate oxidation reaction product of the aromatic raw material has not been recovered from the liquid. At least a portion of the mother liquor is returned to the reaction zone of at least one liquid phase oxidation reaction such that it can be used in a liquid phase reaction, such as a catalyst, a solvent, and a by-product which can be converted to the desired aromatic carboxylic acid, to be reused. In a preferred embodiment of the present invention, the liquid phase reaction product mixture comprising the aromatic carboxylic acid and the liquid phase oxidation reaction by-product obtained by oxidation is recovered in a liquid by crystallization by stages, for example, in a series of crystallization vessels, The temperature and pressure are sequentially decreased from the early stage to the later stage to increase the recovery of the product. Crystallization is carried out in two to four stages, for example, from an oxidation reaction temperature of from about 140 to about 250 ° C and a pressure of from about 5 to 40 kg/cm 2 gauge, to a final crystallization temperature of from about 110 to about 150 ° C and a pressure of atmospheric pressure. To a pressure of about 3 kg/cm2 gauge, the solid aromatic carboxylic acid product can be substantially crystallized. The oxidized mother liquor separated from the solid product by crystallization can be returned to the reaction zone as described above. The gas phase formed by flashing or otherwise reducing the pressure of the reaction product mixture removes heat from the crystallization vessel, and the vapor phase removed from one or more stages is preferably condensed and directly or indirectly The ground is passed through one or more additional recovery stages, as described below, and at least a portion is returned to the reaction zone for use in a liquid phase oxidation reaction. The solid product recovered from the liquid phase oxidation reaction, usually containing an aromatic carboxylic acid and an impurity of an intermediate oxidation product including an oxidation by-product such as an aromatic raw material, may be any suitable from the liquid oxidizing mother liquid obtained by recovering the solid product. Separated by technology. Examples include centrifugation, vacuum filtration, pressure filtration, and filtration using a belt filter. The obtained solid product is preferably washed after separation using a liquid containing water (such as pure water) and a cleaning liquid containing a small amount of a solvent monocarboxylic acid, a catalyst, an aromatic raw material, and an oxidation reaction product. Alternatively or in combination, the liquid may advantageously be recycled to the oxidation reaction, either directly or in combination with other liquids, such as oxidizing mother liquor recycle or other liquids that are returned to the reaction zone. The separation of the solid, impurity-containing aromatic carboxylic acid recovered from the oxidizing mother liquor and the cleaning of the solid product can be conveniently accomplished by a solvent exchange pressure filtration using a pressurized filter, such as disclosed in U.S. Patent No. 5,679,846. And those disclosed in No. 5,200,557. A preferred filter unit for performing the separation is a BHS Fest filter, which is described in detail in U.S. Patent No. 5,200,557. The oxidizing mother liquor and washing liquid removed from the filter cake can be directly or indirectly transferred to a liquid phase oxidation reaction. The solid product is washed in multiple stages using a cleaning solution with a 20-fold increase in purity, for example with the liquid removed from the filter cake in the downstream stage as the washing liquid in the previous stage, by moving from the filtered solids The removal of the solvent monocarboxylic acid for concentration to return to the oxidation reaction provides additional advantages. In a more specific embodiment, the filter cake wetted with the cleaning fluid obtained from such advantageous removal filtration is directed from a final cleaning stage to a

twenty one

V 1359132 The drying stage 'in this drying stage is selectively contacted with an inert gas, usually at low to medium pressures' to remove most of the residual liquid from the filter cake. After cleaning the solid product containing aromatic carboxylic acids and by-products and removing most of the liquid therein, the resulting solid can be dried and stored or 5 directed to other steps, including preparation of a solid product for purification. Reaction solution. Preferably, the residual solution monocarboxylic acid contained in the solid product guided to the purification reaction is contained in an amount of about 5 〇〇〇 ppmw or less. The solid product can be dried with a stream of nitrogen or other inert gas to reduce the amount of residual solvent. The vapor phase (also known as the reaction overhead vapor or reaction vapor phase) in the reaction zone above the liquid reaction mixture contains solvent and water. The overhead vapor may also contain unreacted oxidizing gases, gaseous reaction by-products such as carbon oxides, gaseous by-products such as methyl bromide, catalysts or combinations thereof. If air is used as the oxidizing gas, then the overhead vapor of the reaction typically contains solvent, water, 15 excess oxygen (if any), carbon oxides, nitrogen, and reaction by-products. A portion of the reaction vapor phase is moved from the reaction zone to a separation zone where high efficiency separation is carried out to separate the solvent and moisture from the overhead vapor of the reaction. As used herein, "high-efficiency separation" means separating a component mainly containing a reaction solvent from a reaction overhead vapor such that at least about 95% by weight of the reaction solvent present in the reaction overhead vapor is removed. Preferably, the high-efficiency separation is carried out such that the reaction solvent content in the generated high-pressure overhead gas stream does not exceed about 5% by weight, more preferably not more than about 2% by weight, most preferably not more than about 2% by weight, of the reaction solvent in the overhead vapor. Good land does not exceed 1% by weight. Efficient separation helps reduce solvent loss and helps reduce the amount of supplemental solvent used in the reaction. High efficiency separation also leaves most of the water in the gas phase for t recovery. This high-efficiency separation produces a bottoms stream and a high-pressure tower overhead gas. The bottom of the column is returned to the reaction zone in whole or in part to enhance the flow of the bottoms. The bottoms stream may also contain heavy impurities, by-products, catalysts, water or a combination thereof. Preferably, the two liquid machine 3 has a separation of 35 wt% of water, more preferably less than wt%, of such enthalpy efficiency, under a pressure such that the ε force of the high pressure tower top gripper is a reaction The pressure is at least about 8%, preferably at least about 9 (10), and more preferably at least about 95%. Those skilled in the art will appreciate that high efficiency separations can be carried out at pressures greater than the reaction pressure, but in practice, such high efficiency separations are preferably carried out under pressure to allow the pressure of the high pressure overhead gas stream to eve The predetermined pressure of the apparatus for the separation pressure of about 丨 (8)% of the reaction zone is preferably at least about 8 G% of the oxidizing reactor or the pressure of the reaction zone of the oxidation step of the process, and more preferably touches about 1 vent. The phase is derived from the reaction zone for separation. The reaction vapor phase can be directly moved from the reaction zone of the liquid phase oxidation reaction to the separation zone where the BU is directly connected to the oxidation reactor or other anti-ship or directly connected to it, or indirectly installed. For example, by appropriate conduits, valves, pumps, and the like, it is possible to achieve the purpose of transportation. A small portion of the high pressure and high temperature reaction vapor phases from the liquid phase oxidation reaction can be directed to other uses, such as for the production of high pressure vapors and heat exchange fluids. Preferably, the vapor phase moved to the separation unit is maintained at a sufficient temperature and pressure such that at least a substantial portion of the reaction vapor phase entering the separation zone is retained and the reaction vapor phase provides sufficient heat for separation. 1359132 Contact with the return liquid supplied to the separation zone. Optimally, the passage from the reaction vapor phase to the separation zone is either directly from the reaction zone or via a suitable pressure rating line such that the temperature of the vapor phase entering the separation zone is not colder than the reaction temperature in the liquid phase deuteration reaction. The pressure of the vapor phase 5 entering the separation zone is not more than about 3 kg/cm 2 or more than the pressure in the liquid phase oxidation reaction. According to the present invention, the separation zone for treating the vapor phase of the reaction may comprise any means suitable for separating the water in the high temperature and high pressure reaction vapor phase from the solvent mono-acid. 'δ玄反应Vapor phase system from the liquid phase oxidation reaction It is taken out and stored in the apparatus at a high temperature and a high pressure to obtain a solvent-free monocarboxylic acid-containing bottom liquid stream, and a high-pressure overhead gas stream containing water, as described above. Preferred separation devices are various columns or columns, commonly referred to as distillation or distillation columns, dehydration columns, rectification tubes, water removal lines, and high efficiency separation units designed to pass gas and liquid phases therethrough. Contacting to effect mass conversion between phases in multiple theoretical equilibrium stages 'sometimes also referred to as 'theoretical trays,', 15 so that the gas phase is separated or distributed into parts with various boiling ranges, making it rich A liquid phase having at least one higher boiling component (e.g., the solvent monoterpene acid in the process) is condensed from the vapor phase, leaving substantially less than the one or more lower boiling points The gas of the species (e.g., water in the gas phase of the oxidation reaction in the present process). The temperature of the autoclaved gas phase removed from the oxidation reaction is generally sufficiently high that there is no need to re-boiling outside the liquid phase oxidation reaction. The reverse flow of the gas phase and the liquid phase, for example, by introducing a gas phase into the lower portion of the device and refluxing the liquid in the upper portion, such reverse flow is to increase the contact between the gas phase and the liquid phase in the separation device. Best embodiment provided by the internal structure of the gas - liquid contact surface of such contact can also improve the lift.

twenty four

V For example, the separation zone consists of a steaming tunnel containing high-efficiency packing, sifting elements, valve parts or bubble cap trays. One of the industrially available high efficiency fillers for high efficiency steam tubes is Koch FLEXIPAC from KGGP LLC. Preferably such a distillation tube has at least about 30 theoretical stages' more preferably at least about 5 theoretical plates. The reflux of such a distillation column may include a mother liquor from a compatible process, such as a mother liquor from an aromatic carboxylic acid purification process. An aqueous reflux system is supplied to the separation zone for contact with the high pressure reaction vapor. Any suitable source of liquid containing water and substantially free of impurities that are detrimental to separation may be employed. A preferred source of reflux liquid comprises a liquid condensed from a high pressure gas removed from the separation and/or condensation zone of the process. In a preferred embodiment, described in greater detail herein, the purified mother liquor obtained by recovering the purified aromatic carboxylic acid product from a purified liquid reaction mixture is sent for separation such that the reflux liquid supplied to the separation zone contains the purified mother liquor. The supply of the reflux liquid is supplied at a rate and temperature of heat welding of the liquid phase oxidation reaction which is effective to move the oxidation reaction to the separation zone in the reaction vapor phase. When the separation zone is coupled to the reactor from a liquid phase oxidation reaction to substantially move the reaction vapor phase from the oxidation reaction to the separation zone, the function of the reactor is as a reboiler. In such an embodiment, the rate at which the reflux liquid is supplied to the separation zone is conveniently expressed as the weight of the liquid supplied to the zone relative to the weight of the aromatic hydrocarbon feed to the liquid phase oxidation reaction. Preferably, the temperature of the reflux liquid supplied to the separation zone is from about 120 ° C to about 170 in accordance with the present method. The range of (:, more preferably, the range of from about 13 CTC to about 160 ° C. At such a temperature, the liquid is preferably introduced into the separation zone at a rate of 4 1359132 to 5 parts by weight of liquid per part by weight. An aromatic hydrocarbon precursor to the liquid phase oxidation reaction. The separation zone according to the present invention may comprise a single device or multiple devices arranged in sequence, such as columns, columns or other structures. When two or more devices arranged in sequence are used When they are formed and their respective inlets and outlets are connected, the high pressure reaction vapor phase removed from the oxidation reactor flows into and through these devices, and the water and high pressure reaction vapor phase and countercurrent are contained therein. The C1-C8 monocarboxylic acid in the liquid is separated, and the countercurrent liquid comprises a reflux liquid separated from the high pressure reaction vapor phase and a liquid containing 10 monocarboxylic acid, which is located inside or between the devices, so that the solvent is rich in monocarboxylic acid. The acid but the liquid containing a small amount of water can be withdrawn from the first device arranged in sequence, and the high-pressure gas-phase overhead gas stream separating the obtained water vapor and substantially free of the low molecular weight monocarboxylic acid solvent can be obtained from the The last device in the arrangement is removed. A high pressure overhead gas stream is withdrawn from the separation zone. Other gas streams can also be selectively withdrawn from the separation zone or from the high pressure overhead gas stream. This other gas stream can be used It can be routed to downstream or upstream equipment, for example, or can be used in other processes to provide high pressure overhead gas flow or to extract heat. Typically, the high temperature overhead gas stream leaves the separation zone. More than about 100 ° C, preferably greater than about 120 ° C, and less than about 250 ° C, preferably less than 20 ° C, and a pressure in the range of from about 4 to about 40 kg / cm 2 gauge. Usually, The temperature of the high pressure overhead stream leaving the separation zone is about 〇 ° C to 20 ° C lower than the temperature of the oxidation reactor, preferably about 5 ° C to 15 ° C lower than the temperature of the oxidation reactor. Usually, high pressure The pressure of the gas stream overhead stream exiting the separation zone is about 0 to lkg/cm2 gauge pressure lower than the pressure of the oxidation reactor. 26 1359132 The high pressure overhead gas stream contains most of the water in the overhead vapor of the reaction column, typically greater than about 35 % by weight, preferably at least 50% by weight, more preferably 70% by weight» Preferably, the high pressure overhead gas stream contains at least about 60% by volume water, preferably at least about 65% by volume water. Typically, the high pressure overhead gas stream may also contain carbon oxides, nitrogen, unconsumed molecules. Oxygen and oxidation by-products such as alkyl bromide. The high pressure overhead stream from the separation zone is directed to a condensing zone where thermal energy is withdrawn from the high pressure overhead gas stream. The condensing zone may comprise any which may be substantially free of Means of impurities and condensation of water introduced into the condensing zone from the high pressure gas, the apparatus is also capable of extracting thermal energy, preferably substantially not reducing the pressure by 10, thereby reducing energy loss. Preferably, the condensing zone includes One or more condensers or heat exchange means, preferably a heat exchange fluid, providing an indirect heat transfer between the high pressure overhead gas stream and a suitable heat dissipating material. A single device or multiple devices in series can be used. Shell and tube heat exchangers and kettle condensers are examples of preferred devices. All or 15 substantially all of the high pressure overhead gas stream resulting from the separation is preferably directed to the condensation zone so that the energy and materials can be recovered substantially therefrom. The cooling is preferably carried out under conditions such that the pressure is substantially not lower than the condensation zone of the high pressure gas introduced into the condensation zone. The exhaust gas still exists after being condensed and is withdrawn from the condensation zone. The condensing zone exhaust gas comprises water, 20 parts of non-condensable high-pressure gas from the separation zone, gas phase reaction by-products and a small amount of aromatic raw materials, the temperature of which is preferably about 50 to about 15 GC ' and the pressure is not condensed. The pressure of the gas in the zone is lower than about 3 kg/cm2. More preferably, the pressure difference between the gas withdrawn from the separation device and the condensing zone exhaust gas after condensation of the condensate is about 2 kg/cm2 or less, preferably about 0.5 to about 1 kg/cm2.

27 Misplaced heat exchange with a heat dissipating material, heat is extracted from the high pressure overhead gas stream, and the heat dissipating material is heated. The heat dissipating material is preferably a hot liquid, preferably S water. When the water is aged, the heat exchange with the separated pressurized gas preferably converts the water into a vapor which can be introduced into other elements of the process for heating or similar to the method. The heat can be extracted from the high pressure overhead stream by heat exchange with liquid from other process steps. In a preferred embodiment of the method of the present invention, heat is extracted from the high pressure overhead gas stream by heat exchange with an aqueous heat exchange fluid, and the heat exchange is at a series of continuously cooled temperatures. The heat exchange of the lower operation is performed such that vapors of different pressures can be generated from the heat exchange hydrophobic water. The vapors of different pressures are preferably directed to one or more process steps, the towels of which are heated under the corresponding pressure. In this series of heat exchangers, a condensate containing water having a continuously reduced temperature is produced. The extraction of heat energy in the condensation zone can be carried out in a single step. It can also be carried out in multiple steps to carry a high pressure column which is removed from the separation zone. The gas stream of the top gas stream is cooled to a first temperature in a first stage to produce a first stage condensate and an uncondensed gas portion, and then the gas portion is condensed to a lower portion in a second stage. Temperature to provide a second stage condensate, and an uncondensed portion of the gas introduced to the second stage, and one or more additional stages as needed, wherein the gas from the previous stage The uncondensed portion is condensed at a lower temperature than the previous stage to form a condensate and a remaining uncondensed gas portion. By means of the pressurized gas and the uncondensed portion of the condenser in each stage The heat exchange between the gases and the heat extracted from the high pressure overhead gas stream provides heat exchange fluids of different pressures and temperatures, 1359132 such as medium pressure and low pressure steam, which can be used for heating in other process steps or for use in the process. In addition, in a preferred embodiment of the invention, two or more levels of vapor are produced for energy recovery, which may conveniently be accomplished by a condensing or other low pressure steam turbine. In this embodiment, Condensate removed at 5 different temperatures can be introduced into other processes with corresponding temperatures, thereby eliminating additional heating or cooling of the condensate. At higher temperatures (eg, about 13 〇. 16 (TC range) recovered condensate, very suitable for reflux to the separation zone, either alone or in combination with aqueous solutions from other process steps, for example, with one purification step and/or separation The mother liquor retained after the aromatic carboxylic acid is combined. The low temperature condensate, for example, the temperature is fine to the thief, and is not suitable for the use of the feed condensate, such as the cleaning solution used for product separation, and the seal in the liquid gas oxidation reaction. The rinsing liquid, even the cooler condensate, for example from about 4 Torr to about 5 Torr, is used as a cold condensate, such as a cleaning solution. The use of certain condensates may include the treatment of steam. To remove impurities, or to change the composition or state of the condensate. The enthalpy is extracted from the condensing zone so that only a portion of the water in the high pressure overhead gas stream is condensed in the condensing zone. The condensate from the high pressure overhead gas stream is formed in a condensation zone containing about 60% by weight of water, preferably 5% by weight or less, and more than 20% of the high pressure overhead gas stream. The weight %, preferably more than 3% by weight, reduces the efficiency of heat exchange as an energy recovery method when each additional weight % of water is condensed. Partial condensation in such a range increases the total amount of energy recovery, but avoids a range in which the heat exchange efficiency is greatly reduced. Partial condensation

29 1359132 enables heat to be recovered from the high pressure overhead stream, leaving a sufficient amount of uncondensed water for further energy recovery in the form of “work”. Even if only a small amount of energy is recovered through the partial condensation step itself, the uncondensed portion of the high pressure overhead vapor retains a considerable amount of energy and can be recovered into a "work" shape, so that the total energy recovered from both Energy that is greater than the energy recovered from the complete condensation process or from a process that only recovers energy in the form of "work". The extracted heat can be used elsewhere in the process or in related processes. The portion of the high pressure overhead vapor that is not condensed in the condensation zone, referred to herein as high pressure exhaust gas, retains from about 40% to about 80% by weight of water from the high pressure overhead stream. The high pressure exhaust gas is sent directly or indirectly to an expansion zone where energy is recovered from the high pressure exhaust gas in the form of "work". The expansion zone includes one or more devices for recovering energy in the form of "work", preferably in an isentropic manner, and more preferably one or more expanders or devices. Those skilled in the art will understand that isentropic devices are not really isentropic. In fact, changes in entropy can occur. Preferably, however, the isentropic energy recovery mode employed has a change in entropy of less than about 30%, more preferably less than about 25% change in entropy, and optimally less than about 20% change in entropy. In the extraction zone, "work" is extracted from the high pressure exhaust gas and an outlet gas vapor having a lower pressure than the high pressure exhaust gas 20 is formed. In the expansion zone, "work" extracted from the high pressure exhaust gas can be used, for example, using a generator to generate electrical energy, or for operating a configuration requiring mechanical work, such as a compressor. This extracted energy can be used in the process, used in other processes, can be stored or sent to a power grid for delivery to

30 1359132 Other premises. In certain embodiments, 'reactors are placed in accordance with this aspect of the invention, which are rated at -the first pressure and are suitable for liquid phase oxidation reactions'. The reaction is an aromatic hydrocarbon feedstock with gaseous oxygen in a single In a liquid phase reaction mixture of acid and water, the reaction conditions are such that the reaction mixture can be maintained and a high pressure vapor phase is produced, the reactor having up to 1 vent to discharge high pressure overhead vapor from the reactor; Arranging the system at a second pressure, which is less than the first pressure, and 10 contains at least a gas inlet that is in fluid communication with the reactor for receiving at least one vent from the reactor The high pressure overhead vapor exiting, w.v. the liquid inlet, for directing the reflux liquid to the high efficiency separation unit, at least the emulsion outlet for removing the high pressure overhead vapor from the apparatus, at least one liquid outlet for The high-efficiency separation device removes the bottom liquid stream, and a sub-diet zone, located between at least one gas inlet and at least one gas outlet, and capable of separating 15 20 of efficiency, and will be charged to the reactor tower in the apparatus The solvent monocarboxylic acid disk in the top vapor is separated by water to form a bottom liquid stream and a high pressure overhead gas stream, the bottom liquid stream containing less than 35% by weight water, preferably less than 25% by weight water, The high pressure overhead gas stream comprises water and no more than 5% by weight, preferably no more than 2% by weight, more preferably no more than 1% by weight of the solvent monocarboxylic acid present in the overhead vapor of the reactor; a condensing unit containing at least a gas inlet for receiving a high pressure overhead gas stream removed from at least one gas outlet of the separation device; a heat exchange interface for transferring heat from a high pressure overhead vapor in the condensation device to a suitable heat dissipation material Having a condensate containing from about 2% by weight to about 60% by weight of water in the high pressure overhead gas stream condensed from the high pressure overhead gas stream

31 to 'and form a high-pressure exhaust gas containing about 40% by weight to about 80% by weight of the adjacent water in the high-pressure overhead gas stream' and a suitable heat-dissipating material to form a higher temperature or pressure; and an expansion device for extracting energy to become "work" , in the form of, containing at least - gas human alpha for receiving high pressure exhaust gas directly or indirectly from the condensing device, and at least - gas out σ for discharging the outlet gas vapor, the dust force being lower than the inlet pressure. It is understood that energy is a form of work before it is understood. It can be understood that this treatment affects the amount of energy that can be recovered from high-pressure exhaust gas. Preferably, a combination of treatments or treatments, if used, is a high-pressure exhaust gas. The water in the extraction zone is sufficiently gaseous in the extraction zone to be sufficiently gaseous before the recovery of the working energy, so that the recovery of the working energy does not cause significant condensation of the water. A combination of various treatments can also be used. For example, the town conducts high-pressure exhaust gas. Treatment to remove corrosive or flammable materials. Although any treatment can be used to remove corrosive or flammable from high pressure exhaust gases. Preferably, the condensation of liquid water is preferably not carried out, preferably by subjecting the high-pressure exhaust gas to thermal oxidation treatment, and more preferably to catalytic thermal oxidation treatment. This treatment usually involves heating an uncondensed pressurized gas. The gas comprises pressurized exhaust gas removed by condensation, or after washing or other treatment, and gaseous oxygen having high pressure and high temperature in the combustion zone, the pressure is not significantly lower than the pressurized gas, and the temperature is sufficient to oxidize An organic, combustible and rotten component that becomes a less corrosive or environmentally compatible gas containing carbon dioxide and water. It is heated under pressure with oxygen, preferably in a suitable oxidation catalyst. Exist in the combustion zone to interrupt the flow of pressurized gas therethrough. The pressurized gas can be selectively preheated by 1359132 before the oxidation reaction. Preheating can be accomplished by any suitable means, for example by Heat exchange, direct vapor injection or other suitable means. Alternatively, the combustion treatment may also include washing a pressurized gas obtained by combustion to remove acid. Inorganic substances, for example, when bromine is derived from a liquid phase oxidation reaction, 5 bromine and hydrogen bromide formed by oxidation of an alkyl bromide present in the exhaust gas of the condenser. Catalyst for catalytic oxidation reaction Containing at least one transition metal element in the periodic table ((1) pAC). The third group metal is preferred, and platinum, palladium and its combination with one or more additional or auxiliary metals are particularly preferred. The agent metal may be used in a composite form, such as an oxide. Typically, the catalyst metal is on a carrier or carrier material that has a lower catalytic activity or no catalytic activity, but has sufficient strength and stability. The oxidizing environment is suitable for the temperature and high pressure of the combustion zone. Suitable catalyst carrier materials include metal oxides containing one or more metals, such as aluminum-rich 15 andalusite, spinel, stone less ore, Shi Xishi, Ming Shi Xi Shao Shi, titanium dioxide oxidation error. Various crystalline forms of such materials can be used, such as alpha, ruthenium, § and ^alumina, rutile and anatase titanium dioxide. The loading amount of the catalyst metal on the carrier composition is preferably several parts by weight. When a gas containing a large amount of water vapor content (e.g., 20% by volume or more) is treated, the higher the loading amount, the more suitable it is. The catalyst can be used in any convenient form, shape or size. For example, the catalyst can be in the form of flakes, granules, rings, spheres or the like, and can preferably be formed or placed in a honeycomb, perforated or porous configuration to aid in the presence of gases in the combustion zone. Contact without blocking the flow of gas through the zone. According to the present invention, in the exhaust gas treatment, a specific example of the catalytic oxidation reaction catalyst used for the combustion treatment of the condensed shifted exhaust gas contains about half to about 1% by weight of palladium supported on the aluminite monolithic support. The high pressure exhaust gas or a portion thereof may also be selectively heated to preserve the water contained in the high pressure exhaust gas completely converted into steam before the energy is recovered into a "work" form, and to avoid condensation of water in the extraction zone. The equipment used for the injury. This heating step may occur before or after any other treatment, such as before or after, such as a thermocatalytic oxidation reaction. In this embodiment, the heating of the exhaust gas may be accomplished by any suitable means, such as heat. Exchanger, direct vapor injection or other means known to those skilled in the art. Heating to a temperature of about 2 ° C or more is generally sufficient to avoid condensation of water in the expansion zone, preferably at a temperature of from 25 ° C to about 350 ° C. When the working energy is extracted from the high pressure exhaust gas, the exhaust gas obtained from the expansion zone is preferably subjected to additional treatment, for example, washing with an alkali to remove any adverse atmospheric emissions of compounds such as bromine or other teeth. a compound. The water in the exhaust gas can be withdrawn and recycled for use in other methods 'or abandon' or undergo further processing or other techniques. Known uses. In the past, attempts have been made to recover energy from the high-pressure overhead gas stream formed during the liquid phase oxidation of aromatic hydrocarbons to produce aromatic tannic acid, either without a condenser or by means of complete condensation. Even if condensing and then expanding in the recycling scheme in the past month, it only uses the complete condensation method. σ人.3⁄4 poetry discovery 'borrower makes partial pressure condensation on the top of the tower pressure' Energy is drawn 1359132 by heat exchange with a suitable heat dissipating material, and the working energy is recovered from the resulting high pressure exhaust gas, and the energy recovery thus achieved is significantly more condensed than all or substantially all of the water in the high pressure vapor. The method or the method of recovering energy in the form of "work" mainly achieves a greater amount of energy recovery. Only the water of part 5 of the high-pressure overhead vapor is condensed, and remains in the high-pressure exhaust gas leaving the condenser. There is a sufficient amount of water to help the energy recovery into a form of “work.” Industrially, in the process of producing aromatic carboxylic acids from aromatic hydrocarbons, The process of extracting energy from the overhead vapor of the reactor includes expanding the exhaust gas by substantially completely condensing and then expanding the exhaust gas, by separately extracting the working energy, 10 or by subjecting the high pressure overhead gas to each of the methods. While some of these methods provide significant advantages, some of the above-described various preferred embodiments do not cause significant differences in total energy. This result implies partial condensation and then extraction of working energy. A large amount of energy is obtained. This result means that the energy recovered without condensing through the high pressure overhead vapor is approximately equivalent to the energy recovered from the subsequent working energy extraction. I was surprised to find that by partially condensing the high pressure overhead vapor The recovery of energy, as well as the recovery of additional energy from subsequent work energy extraction, has a significant increase in energy recovery. In a particular embodiment, the invention is a boiling liquid phase for a 20 aromatic hydrocarbon feedstock containing para-xylene. The oxidation reaction produces terephthalic acid. The liquid component containing the aromatic hydrocarbon raw material and the solvent is continuously introduced into the reactor. Catalysts and promoters are introduced into the reactor, and are preferably dissolved in a solvent. Acetic acid or acetic acid solution is a preferred solvent, and a solvent to raw material ratio of about 2:1 to 5:1 is preferred. The catalyst preferably contains a combination of manganese, decoration, error, or

35 its combination, and the source of bromine. The catalyst is suitably present in an amount to provide from about 600 ppmw to about 25 ppm by weight of catalyst metal based on the weight of the aromatic hydrocarbon and solvent. The promoter is preferably present in an amount such that the atomic ratio of bromine to catalyst metal is from about 0.4:1 to about L5:1 beta oxidizing gas, most preferably air, supplied to the reactor at a rate of energy per mole of aromatic hydrocarbon feedstock. Effectively providing at least about 3 to 5.6 moles of oxygen such that the reactor overhead vapor contains from about 5 to about 8 volume percent oxygen (measured on a solvent free basis). In this particular embodiment, the reactor is preferably maintained at a pressure of from about 15 Torr to about 225 ° C and a pressure of from about 5 to 40 kg/cm 2 . Under such conditions, contact of oxygen and the feedstock in the liquid causes The formation of solids on the formation of stearic acid crystals. The knot B0 is usually in the form of particles. The solids content of the Fotten slurry is usually up to about 40% by weight, preferably from about 35% by weight of the Congru, and the water content is usually from about 5 to about 20% by weight on the basis of the weight of the solvent. Boiling (4) to control the exotherm of the reaction causes the volatile components of the liquid, including the solvent and water of the reaction, to evaporate in the liquid. Unreacted oxygen and evaporated liquid components will detach from the liquid and carry out the reactor space above the liquid. Other species, such as nitrogen and other blunt gases (if air is used as the oxidizing gas), carbon oxides and by-products of evaporation, such as decyl acetate or decyl bromide, may also be present in the overhead vapor of the reactor. . The aromatic citric acid reaction mixture is slurried or partially dissolved in the liquid and removed from the reactor. The product vapor can be treated by conventional techniques to separate its components and recover the aromatic carboxylic acid contained therein, usually by crystallization, liquid-solid separation and drying. A more convenient way is to centrifuge, filter or centrifuge and filter the slurry of the solid product in multiple stages. The tetra-product can be recovered by crystallization in a liquid. The liquid H, which contains an aqueous, solvent, unreacted starting material, and usually also contains - or a multi-agent, a promoter and a reaction intermediate, can be returned to the anti-silk. The aromatic acid-acid product recovered from the liquid can be used directly or stored, or it can be purified or otherwise cured. Purification aids in the removal of by-products, as well as the recovered aromatic acid, which is present as impurities. For aromatic tracing acids, such as for stearic dicarboxylic acid and isophthalic acid, purification preferably includes hydrogenation of the oxidation product, the oxidation product is usually dissolved in water or other aqueous solvent, and the hydrogenation reaction is at high temperature and pressure. Next, in the presence of a catalyst, the catalyst contains - a metal having hydrocatalytic activity, such as p-, ruthenium, or ruthenium, which is typically supported on carbon, titanium oxide or other suitable chemically resistant support or carrier material. Above, as a catalyst metal. For example, U.S. Patent No. 4,782, 181, U.S. Patent No. 4,626,598, U.S. Patent No. 4,892,972. If the purification is water as a solvent, washing with water to remove residual oxidation reaction solvent from the solid aromatic carboxylic acid may be used instead of drying. This cleaning can be accomplished by a suitable solvent exchange device, such as a filter, such as U.S. Patent Nos. 5,679,846 and 5,175,355. Alternatively, the mother liquor from the purification process may be sent, in whole or in part, directly or indirectly to a high efficiency separation unit. For example, if one or more high efficiency distillation tubes are used to perform a high efficiency separation, all or a portion of the purification mother liquor can be used as a reflux for one or more such hot tubes. Typically, the oxidizing mother liquor is separated from the unpurified aromatic carboxylic acid product by conventional separation techniques, such as filtration 'centrifugation, or a combination of known methods 1359132. Preferably, at least a portion of the mother liquor is recovered, and industrial operations typically recover a substantial portion of the mother liquor. For example, such a mother liquor can be recovered directly or indirectly to an oxidation reactor or a high efficiency separation unit. The mother liquor can be separated from the purified aromatic carboxylic acid product by a similar technique' and such a 5 mother liquor can be recycled for use in other stages of the process or in other processes. In detail, according to the present invention, a preferred purification step comprises: dissolving a solid product containing an aromatic carboxylic acid and an impurity in an aqueous liquid to form a purified reaction solution at a high temperature and a high pressure. The purified solution is contacted with hydrogen in the presence of a hydrogen catalyst 10 to form a purified liquid reaction mixture. A solid purified product is recovered from the purified liquid reaction mixture, which contains an aromatic carboxylic acid and a lower amount of impurities, and a recovered solid state. An aqueous liquid purification mother liquor containing oxidation by-products, hydrogenated products thereof, and combinations thereof is isolated from the purified product. The impurity-containing aromatic carboxylic acid is subjected to a hydrogenation reaction to reduce the impurity content. This hydrogenation reaction is carried out in an aqueous solution using an impure acid. The concentration of the impure aromatic carboxylic acid to be treated in a purification step in the purification solvent is sufficiently low that the impure acid is substantially soluble and sufficiently high enough for the actual process operation, and for efficient use and handling. 20 is a liquid as a solvent, and remains as a purification mother liquid after recovering a pure aromatic carboxylic acid containing a lower impurity from the purification reaction mixture. More suitably, from about 5 to about 5 parts by weight of impure aromatic carboxylic acid per 100 parts by weight of the solution provides a solubility sufficient for practical operation at the process temperature. The preferred 38 5 't-tonification reaction solution contains from about 10 to 40% by weight, preferably from about 20 to 35% by weight, of the impure aromatic carboxylic acid at a temperature to be purified by catalytic hydrogenation. The catalyst used in the purification of the hydrogenation reaction comprises one or more metals which are catalytically active for the hydrogenation reaction of impurities in the impure aromatic carboxylic acid product, such as oxidation reaction intermediates and by-products and/or aromatic carbonyl complexes. 10 15 The tincture metal is preferably supported or supported on a carrier material. The carrier material is insoluble in water and under the conditions of the purification method, the catalyst metal with the aromatic (tetra) nucleus is not suitable for the antibiotic, and the elemental periodic table (lupAc) Version) The vm family 2 genus' includes ΐε, m, hungry, sputum, silver, and combinations thereof. It is best to combine the combination of these or sharp metals. It has hundreds or thousands of surfaces, has sufficient strength under operating conditions, and has extended use: shellfish: carbon or activated carbon is a preferred carrier. The metal loading is not, but a preferred loading of from about 0.1% to about 5 parts by weight, based on the total weight of the support and catalyst metal. The preferred catalyst for the conversion of (4) in the presence of (π) aryl (tetra) (tetra) filaments contains about this, pure (4) (10)% metal. For the intended use, the metal is best contained. For practical applications, The catalyst is used, for example, in a granular form to form a granule, globular or granular form, although other solid beds may be used; Purify the reactor, but make the purified anti-product ~ drop through the catalyst particles. The preferred average county... 胄 Unwanted pressure screen occurs: in order to make the catalyst pole pass through the -2- mesh - stay A 24' mesh screen (US mesh series), and preferably 39 1359132, passes through a 4-mesh screen, but remains on a 12-mesh screen, optimally 8 · In the presence of a catalyst for purification, the contact of the purified aqueous solution with hydrogen is preferably at a high temperature and a high pressure, and the temperature ranges from 200 to about 37 〇〇c, and 225 to about 5 325 ° C is preferred, and Approximately 240 to about 3 〇〇t is optimal. The pressure is sufficient to maintain the liquid phase containing the reaction. The level of the solution. The total pressure is at least equal to the sum of the partial pressure of the hydrogen which is preferably introduced into the process at the operating temperature and the partial pressure of the water vapor which is boiled from the aqueous solution. The preferred pressure is about 35. More preferably, about 70 to about 5 kg/cm2. 10 The contact of the purified aqueous solution with hydrogen is carried out under hydrogenation conditions, as described above, and is capable of withstanding the reaction temperature and pressure and the acidity of the liquid. The intrinsic reactor is carried out. A preferred reactor shape is a rounded body reactor having a generally central axis which is vertical when the reactor is positioned for process use. Upflow and downflow The reactors can all be used 15. The catalyst is typically present in the reactor in one or more solid particle beds maintained by a mechanical support to maintain the 2 catalyst particles in the particle bed. While the reaction solution can be relatively free between the flow faces, a single catalyst bed is generally preferred, although multiple beds of the same or different catalysts, or with multiple layers of different catalysts (eg, for large particles) J, force 20 hydrogen catalyst metal or metal loading, or a single bed containing catalyst and other substances used to protect the λ catalyst, such as abrasives, may also be used and may have advantages. Mechanical carriers are often used. Such as a flat screen or a grid formed by suitably spaced parallel lines. Other suitable catalyst retention devices include, for example, Johnson screen or a perforated plate. Inner enthalpy 40 1359132 兀 and reactor The surface and the mechanical carrier of the catalyst bed have a suitable anti-corrosion property to resist corrosion caused by contact with the acidic reaction solution and the reaction product mixture. The carrier of the catalyst bed has an opening of about 1 mm or less. The best 'and is made of metal, Example 5 is not mine, titanium or Hastelloy c. In a preferred embodiment of the invention, the impure aromatic acid aqueous solution to be purified is added to the reactor from the top and near the top of the reactor at elevated temperature and pressure, in the presence of hydrogen. The solution flows downward through a catalyst bed housed in the reactor, wherein the impurities are reduced by hydrogen and are reduced to a hydrogenated product in a state of more than 10 conditions, the solubility in the reaction mixture being greater than the desired aromatic carboxylic acid, or The tendency to form a color is low. In this preferred mode, the liquid purification reaction mixture containing the aromatic carboxylic acid and the hydrogenated impurities are removed from the lower portion of the reactor or near the bottom of the vessel. 15 The reactor used for purification can be operated in various modes. One mode is to maintain a predetermined level in the reactor and to feed hydrogen at a rate sufficient to maintain a predetermined level for a predetermined reactor pressure. The difference between the actual reactor pressure and the vapor pressure of the evaporated purified solution present in the reactor overhead space is the partial pressure of hydrogen in the overhead space or 20 'hydrogen can be mixed with an inert gas such as nitrogen or steam. Feed, in this case, the difference between the actual reactor pressure and the vapor pressure of the evaporated reaction solution present in the reactor overhead space is the sum of the partial pressure of hydrogen and the partial pressure of the mixed inert gas. In this case, the partial pressure of hydrogen can be calculated from the known relative amount of hydrogen and inert gas present in the mixture.

41 1359132 In another mode of operation, the reaction solution can be injected into the reactor such that there is substantially no space for the reactor vapor at the top of the reactor or at the top of the reactor, and only gas bubbles, which expand or contract The space providing the top of the reactor is such that the hydrogen gas fed to the reactor can be dissolved in the injected pure 5 reaction solution. In this embodiment, the reactor is operated as a liquid-filled system, and the dissolved hydrogen is fed into the reactor by a flow controller. The concentration of helium in the solution can be adjusted by introducing hydrogen into the reactor. The flow rate is adjusted. If desired, a hypothetical partial pressure of hydrogen can be calculated from the hydrogen influx of the solution, which is then correlated with the flow of hydrogen flowing into the reactor. When operating, the control of the process is affected by adjusting the partial pressure of hydrogen to affect the partial pressure of hydrogen in the reactor, preferably from 1/2 to about 15 kg/cm2 gauge or higher, depending on the rated pressure of the reactor, impure aroma. The impurity content of the carboxylic acid, the activity and lifetime of the catalyst, and other considerations known to those skilled in the art. In some modes of operation involving direct adjustment of the hydrogen concentration in the feed solution, the solution is typically below saturation for hydrogen and the reactor itself is liquid filled. Therefore, adjusting the rate of hydrogen flow into the reactor controls the concentration of hydrogen in the solution. The space velocity, expressed as the weight per unit weight of the catalyst per hour, and the weight of the impure aromatic 20 aromatic acid in the purification reaction solution, 'the space velocity is usually about 1 hour to about 25 hours during the hydrogenation process,' And preferably from about 2 hours to about 15 hours. The residence time of the purified liquid stream in the catalyst bed varies depending on the space velocity. The pure aromatic carboxylic acid is recovered from the liquid purification reaction mixture.

42 1359132 The article 'has less impurities than the crude aromatic carboxylic acid or the other impure aromatic carboxylic acid product used to prepare the purification reaction mixture. a purified reaction mixture containing an aqueous reaction solvent in which an aromatic carboxylic acid and a hydrogenated aromatic impurity are dissolved, the solubility of which is greater in the aqueous reaction liquid than their unhydrogenated precursor, and the purified reaction mixture is cooled down to A pure solid aromatic carboxylic acid containing a small amount of impurities is separated from the reaction mixture, leaving a liquid purification mother liquid in which hydrogenated impurities are dissolved. Separation is usually achieved by cooling to a crystallization temperature which is low enough to crystallize the aromatic carboxylic acid, thereby forming crystals in the liquid phase. The crystallization temperature is sufficient so that the dissolved impurities and the reduced product obtained from the hydrogenation remain dissolved in the liquid phase. The crystallization temperature is usually up to 160 ° C, preferably up to about 150 t. In a continuous operation, the separation typically involves removing the liquid purification reaction mixture from the purification reactor and crystallizing the aromatic carboxylic acid in one or more crystallization vessels. When crystallization is carried out in a series of stages or in a series of separate crystallization vessels 15 'the temperatures in the different stages or vessels may be the same or different, and preferably from each stage or vessel to the next stage or vessel. . Crystallization also typically causes the liquid to flash from the purified liquid reaction mixture, which may be recovered or recycled to one or more purification zones, one or more upstream crystallization stages, or, in a preferred embodiment of the invention, It is recovered or recycled to the separation zone, 20 to separate the solvent monooleic acid from the water vapor in the south pressure gas phase from the liquid gas oxidation reaction. The crystalline, purified aromatic carboxylic acid product is then separated from the purified mother liquor, including hydrogenated impurities dissolved therein. The separation of the crystalline product is usually carried out by centrifugation or filtration. A preferred method of separation comprises pressurizing a pure 43 aqueous aromatic acid aqueous slurry and filtering the resulting filter cake with an aqueous liquid embryo/month wash, as described in U.S. Patent No. 5,175,355. As a reference. The purified mother liquor remaining after recovery of the solid purified aromatic carboxylic acid from the purified reaction mixture contains water and a hydrogenated derivative of by-products or impurities present in the impure aromatic carboxylic acid starting material. The mother liquor also typically contains a small amount of aromatic carboxylic acid remaining in the solution. Such hydrogenated derivatives include compounds suitable for conversion to aromatic carboxylic acids by liquid phase oxidation reactions. Thus, in a preferred embodiment of the invention, at least a portion of such hydrogenated derivatives are directly or indirectly Move into a liquid phase oxidation reaction. The residual aromatic acid retardant present in the mother liquor may be directly or indirectly transferred to the liquid phase oxidation reaction after separation from the oxygenated derivative or, more preferably, with the hydrogenation derivative. The derivative and aromatic carboxylic acid are conveniently transferred to the oxidation reaction by directing at least a portion of the purified mother liquor remaining after separation of the solid, pure aromatic carboxylic acid to a liquid phase oxidation step. The water content of the purified mother liquor will disturb the balance of water in the oxidation reaction, unless the water from the purified mother liquor introduced into the oxidation reaction is exactly equivalent to other liquids which can be returned to the deuteration reaction. Preferably, the migration to the liquid phase together with the aromatic rebellion present in the mother liquor is preferably accomplished without disturbing the water balance in the oxidation reaction. More preferably, at least a portion of the liquid mother liquor remaining after separation of the solid purified aromatic carboxylic acid from the liquid purification reaction mixture, at most substantially, is directly or indirectly transferred to a separation zone for treatment of the exhaust gas, the exhaust gas The treatment is used to treat the high pressure gas phase removed from the oxidation reaction according to the invention, where it is used as a reflux. For example, if one or more column columns are used to separate the solvent monocarboxylic acid and water in the high pressure gas phase formed by the liquid phase oxidation reaction of the aromatic raw material, the purified mother liquor may be used in whole or in part as one or Reflow of multiple columns. The water present in the mother liquor added as the reflux liquid is substantially completely evaporated, enters the gas phase in the column, and the water remaining in the vapor phase from the 5 open column becomes a part of the separated pressurized gas. Higher boiling components in the mother liquor, including hydrogenated impurities, such as by-products of liquid phase oxidation of aromatic feedstocks used for oxidation, and aromatic carboxylic acids, if present, remain substantially liquid phase and may be directly or indirectly Returning to the liquid phase oxidation reaction mixture, for example, as a liquid phase rich in solvent monocarboxylic acid in the liquid stream obtained by separation or removal from the separation reaction 10. The morphological and operational details of the purification reactor and catalyst bed used in the process of the present invention, as well as the crystallization and product recovery techniques and equipment, are described in more detail in U.S. Patent No. 3,584,039, U.S. Patent No. 4,626,: 598, U.S. Patent. No. 4, 629, 715, U.S. Patent No. 4,782,181, U.S. Patent No. 4,892,972, U.S. Patent No. 5,175,355, U.S. Patent No. 5,354,898, U.S. Patent No. 5,362,908, and U.S. Patent No. 5,616,792. Reference materials. Figure 1 illustrates a preferred embodiment of the present invention. The figure shows a preferred apparatus form comprising a reactor having a nominal pressure, the container 20 being formed into a substantially closed interior space 'suitable for accommodating a liquid reaction mixture and a reaction vapor phase, and comprising at least one inlet For introducing a liquid into the internal space, at least one inlet for introducing an oxygen-containing pressurized gas to the internal space 'at least one liquid product outlet for removing a liquid-containing or solid slurry-containing product from the internal space, and at least one exhaust gas a hole 'for removing a 45 1359132 high pressure reaction overhead vapor from the interior space; a separation device in fluid communication with the reactor for containing the high pressure reaction overhead vapor removed from at least one venting port in the reactor, and Included in at least one column containing at least one vapor inlet for receiving the high pressure reaction overhead vapor to flow through the column, at least one liquid inlet, suitable for retracting the liquid to reverse the vapor of the high pressure reaction column Flowing through the column; a device disposed in the column between the vapor and the liquid inlet and providing contact between the gas phase and the liquid phase in the column The surface is such that the high-pressure reaction vapor phase containing the gaseous C1-8 monocarboxylic acid and the water vapor in the charge column is separated into a liquid phase and a high pressure overhead gas stream, which is rich in C1-8 10 monocarboxylic acid But containing only a small amount of water, the high pressure overhead gas stream containing water and no more than about 10% of the C1-8 monocarboxylic acid contained in the high pressure reaction overhead vapor in the column, at least one liquid outlet for removal a liquid, and at least one venting opening, located above the liquid inlet for removing the aqueous high pressure overhead gas stream from the column; at least one condensing device in fluid communication with the separation device for receiving 15 aqueous sorghum tower a top gas stream comprising at least one gas inlet for receiving an aqueous high pressure overhead gas stream, at least one gas outlet for exhaust gas from the heat exchange device, and a heat transfer device for a high pressure overhead gas stream and a heat introduced into the heat exchange device Heat exchange between the transfer medium and condensing a portion of the aqueous liquid from the gas; and expansion means for extracting energy into a "work" form, 20 comprising at least one gas inlet for receiving from the cold It means high-pressure exhaust gas, and at least one gas outlet for discharging waste gas flow pressure lower than inlet pressure. As shown in Fig. 1, the oxidation reactor 4 comprises a substantially cylindrical casing which encloses a substantially closed interior space. When used, the internal space

46 1359132 The lower portion contains a liquid reactant and the reaction overhead vapor is contained in a portion of the internal space above the liquid level. The internal space is communicated with the outside of the reactor via a plurality of inlets through which liquid aromatic feedstock, solvent and soluble catalyst are introduced, and compressed air or another source of oxygen 5 gas is supplied from a compressor Or other suitable device (not shown) is introduced. The locations of these inlets are preferably such that liquid and gaseous components are directed to the interior of the vessel below the liquid level. The oxidation reactor 4 also includes at least one outlet for internally removing a liquid phase reaction mixture comprising a crude product comprising an aromatic carboxylic acid and an oxidation by-product, which is typically present in solution in liquid form, or The solid particles are suspended in a liquid or slurried in a liquid, or simultaneously dissolved and suspended in a liquid. Reactor 4 also includes at least one vent or outlet for removing a high pressure reaction vapor phase evaporating from the liquid phase reactant via line m from the interior of the reactor. The location of such vents preferably corresponds to the upper portion of the container 15 when positioned for process use. A preferred reactor design is a generally cylindrical container having a central axis that extends generally perpendicularly when the container is positioned for process use. The container is adapted for use with a stirring mechanism having a shaft on which one or more impellers are mounted for rotation within the reactor for agitating the liquid reaction mixture present in the vessel during use in the course of 20 passes . In a preferred embodiment of the invention, at least two impellers or mixing equipment are mounted on the shaft for mixing the gaseous and liquid components of the liquid reactant without allowing the solids to settle in the lower portion of the vessel. An axially flowing impeller, generally in the form of a propeller, a radially flowing mixer, such as a flat-blade turbine and sub-div

47 Disc 'Spiral Stirring Element' slanted-blade turbine with blade angle for upflow or down<, anchor mixer, providing flow primarily in tangential direction, and other forms suitable for mixed liquors The phase oxidation reaction system, and preferably used in various combinations, to provide a higher solids content in the lower region of the liquid reaction mixture, and to make the upper portion of the gas content more 'and change throughout the liquid Other features of the liquid phase reaction mixture. Other designs are disclosed in U.S. Patent No. 5,198,156, which is incorporated herein by incorporated herein by reference in its entirety in its entire entire entire entire entire entire portion Blade morphology having a discontinuous leading edge, a continuous trailing edge, no outer recessed surface and an open outer end, and preferably used with a vertical s or perforated gas spray for dispersing gas, and U.S. Patent No. 5,904,423, the disclosure of which is incorporated herein incorporated by incorporated herein incorporated by incorporated herein in the the the the the the Up wedge-shaped, the edge of the radially inner end of the blade angle outwardly in the moving direction of the blade, for introducing a gas into a central recess of the shank at a conical formed from below the agitator. The mixing shaft and the process are in use of a mixing element that contacts the liquid phase reaction mixture with the reaction overhead and gas, and at least these components of the reactor are composed of a corrosion resistant material. Examples include titanium metal and double-refined steel. Metals are preferred. In Figure 1, the reaction overhead vapor from reactor 4 is directed via line U1 to a high efficiency steam column column 6, which contains a highly efficient filler, such as Koch FLEXIPAC, a structural filler from KG (} p llc, and having at least 20, preferably at least 3, theoretical plates. Preferably, the sump column is a column or tower having a rated dust force, or a series of columns or towers. At least one inlet for receiving a high pressure reaction overhead vapor, at least one inlet for introducing a reflux liquid, one outlet for removing the high pressure overhead stream obtained by the separation, and a fractionation zone containing an internal structure to provide a surface for promoting reverse flow The mass conversion between the gas phase and the liquid phase is sufficient to provide a suitable theoretical equilibrium stage for separating the solvent monocarboxylic acid and water in the vapor phase, which is a preferred separation device. Preferably, the device is designed to Introducing an inert gas into the lower portion of the tube or column, and introducing a reflux liquid at a plurality of upper positions relative to the gas inlet, and having a one-stage fractionation zone in the middle such that the upward passage of the gas phase causes passage of the gas The reverse flow 'and the downward flow of liquid that is provided as a reflux and condensed from the rising vapor phase under gravity. Additional features of such a column or column may include one or more outlets or inlets a hole for removal or addition - or a plurality of gas streams or streams, for example, to remove a monocarboxylic acid-rich liquid separated from the vapor phase. The separation device may also have a reboiler or other suitable device. In order to supplement the heat input, although the high-pressure reaction vapor phase from the liquid phase oxidation reactor is not substantially cooled, that is, substantially introduced into the device, such a device does not require 'because of the exothermic nature of the oxidation reaction The oxidation reaction benefit can be effectively used as a monumental device. In a preferred embodiment, a direct connection between the oxidation reaction benefits or the plurality of outlet gases D and the separation device or the plurality of gas inlets or via appropriate A pressure-rated line or other conduit is used to connect the 'oxidation reaction with the separation unit to achieve direct or close coupling so that the reaction H vapor phase is reacted under liquid phase reaction conditions. The separation device is introduced into the separation device at substantially the same temperature and pressure as the reaction zone. 49 1359132 The separation device is preferably capable of separating water in the high pressure reaction overhead vapor introduced into the device from the solvent monocarboxylic acid vapor, Forming a liquid phase containing at least 60 to 85 parts by weight of the solvent monocarboxylic acid per hundred parts by weight of the liquid, and containing 45 to 65 parts by weight of water per high pressure gas per hundred parts. To achieve such a separation, the separation device The fractionation zone is formed with a plurality of balance wheel plates which may be provided by internal disc 'structural packing or other means which may provide a surface inside the apparatus for mass conversion of the gas phase and the liquid phase in the apparatus. For the separation, at least about 2 theoretical plates are preferred. The separation efficiency increases as the theoretical balance plate increases, and the other items remain equal, 10 thus the theoretical tower that can be included in the separation device used in the present invention. There is no theoretical upper limit on the number of plates. However, for practical purposes, the separation is carried out such that the outlet gas from the separation unit contains 10% by weight or less of the solvent monocarboxylic acid content into the inlet vapor phase of the unit, such separation can be achieved by At least about 20 theoretical equilibrium trays are completed, and the degree of separation provided by more than 7 to 15 such trays makes additional trays impractical or economical. A preferred separation apparatus containing structured packing has at least 3 packed bed or packing zone 1 and more preferably about 6 such beds to provide sufficient surface and theoretical equilibrium trays for separation. Example 2 of a suitable filler material is a BeXlpac structured packing from KGGPLLC, which is a corrugated flaky metal arranged in a cross-shaped relationship to create a flow channel and to make the cross-section liquid phase and gas phase of t Mix the dots. In the case of a preferred separating device having a plate, a mesh type disk or a bubble cap tray type is preferred, and preferably has a separation efficiency of from about 4 Torr to about 6%. In terms of a set theoretical balance of 50 1359132 plates, the number of plates can be calculated by dividing the number of theoretical plates by the efficiency of the plates. In the use of the process, the gas phase and the liquid phase introduced into the separation device are at a high temperature, and include water, monocarboxylic acid and other corrosive components, such as bromine compounds and their decomposed products, For example, when the catalyst used in the oxidation reaction contains a source of bromine, hydrogen bromide is present in the gas at the top of the oxidation reaction. Thus, in a preferred embodiment of the invention, the internal structure of the separation device and other features that allow gas-liquid contact during process operation are constructed of a suitable metal to resist the rot caused by such contact and 10 Other damage. Titanium is a preferred material for the construction of such surfaces, including discs, packing or other structures in the fractionation zone. Titanium surfaces of this configuration are likely to be improperly accumulated by solid deposits including iron oxides in impurities present in various process liquids circulating in the apparatus. The method of controlling the accumulation of iron oxide deposits or the amount of soluble iron impurities in the process liquid is described in U.S. Patent No. 6,852,879 and U.S. Patent Application Serial No. 2002/374, the entire disclosure of which is incorporated herein by reference. As shown in Fig. 1, the high efficiency distillation column 6 performs a highly efficient separation of the reaction overhead vapor. The bottoms stream 121 from the high efficiency separation unit and containing primarily acetic acid solvent is returned to the reactor 4. 20 The separation device in the apparatus according to this aspect of the invention is in fluid communication with the condensing means. The condensing device is adapted to receive a gas stream comprising a high pressure overhead gas stream removed from the separation device and adapted to condense a condensate from the high pressure overhead gas stream, the condensate containing water substantially free of organic impurities, and Leaving a high pressure condenser exhaust gas, including the introduction and separation device

The non-condensable component of the gas in 51 1359132, and from about 40% to about 8% water vapor present in the high pressure overhead gas stream. The condensing device also includes at least one outlet for removing condensate condensed from the gas introduced therein, and an indirect heat exchange device for performing heat transfer between the inlet gas and the heat exchange liquid, the heat exchange liquid system Lower temperature or pressure is introduced into the unit and removed at a higher temperature or pressure. The condensing unit optionally also includes means for introducing the condensate into the purification apparatus, the apparatus preferably being in fluid communication with at least one of the containers or the liquid holding means in the purification apparatus, such that the condensate removed via the outlet can be Move directly to the purification unit. The condensing unit 10 may comprise a single or a series of heat exchange devices, such as a shell and tube heat exchanger 'plate and frame heat exchanger or other suitable heat exchange device, wherein heat from the inlet gas is transferred to a heat exchange medium For example, water, steam or another heat transfer liquid 'to increase the temperature or pressure of the heat exchange liquid. It is advantageous to use a series of multiple heat exchange devices to generate vapors or other heat exchange fluids of different pressures or temperatures 15, as well as condensates of different temperatures for use in different vapor pressures and liquid temperatures. . The condenser is typically constructed of a metal or alloy having corrosion resistant characteristics suitable for high temperature vapor phase vapors during circulation and for use in circulating or cooling fluids present therein. It is preferred to not record the inner surface of the steel, although other metals or alloys are also suitable. 20 Referring again to Figure 1 'High pressure overhead gas stream 123 from the high efficiency separation unit and containing primarily unreacted oxidizing gas, is introduced into a condenser 8' and partially condensed therein so that the high pressure overhead gas stream 123 The water, preferably from about 30% to about 50% by weight of the water present in the high pressure overhead stream, is converted to a liquid form and sent via line 125 to the top of the high efficiency steam 52 column 6 For use as a reflux liquid in the column. During partial condensation, energy is extracted by exchanging heat from the condenser 8 with a suitable heat dissipating material such as water. The high pressure exhaust gas 127 is introduced from the condenser 8 into a preheater 10' where it is preheated. The heated high pressure exhaust gas 129 is introduced into the oxidation treatment unit 12' wherein the by-products of the organic component and the heated high pressure exhaust gas 129 are oxidized to a compound more suitable for environmentally friendly treatment. The oxidized high pressure exhaust gas 131 is introduced into an expander 14 which is coupled to a generator 16. The energy from the oxidized high pressure exhaust gas 131 is converted into a "work" form in the expander 14, and this "work" is converted into electrical energy 135 by the generator 16. The exhaust gas 133 exiting the expander 14 is released It is treated before it is sent to the atmosphere. This treatment may include cleaning prior to atmospheric discharge to remove any remaining impurities, such as bromine. This treatment may also include removal of water, which may be used in the process. For the related process, or for other processes, or to abandon. In the existing energy recovery scheme, instead of using the condenser 8 to partially condense the high pressure overhead gas stream 123, the high pressure overhead gas stream 123 is completely condensed. And by exchanging heat with a suitable heat-dissipating material to extract energy during complete condensation. The high-pressure exhaust gas obtained by complete condensation is mostly composed of nitrogen and other uncooled components, and contains only a very small amount of water (if any). The high-pressure exhaust gas from complete condensation can be further recovered by an expander. However, the heat recovery and energy achieved by partial condensation according to the present invention can be achieved. A combination of successful recovery forms, this complete condensation scheme results in significantly less energy recovery. Although partial condensation can result in less energy recovery from the heat extraction process, extraction from ''work,' The resulting increase in energy recovery is greater than the energy of 1359132 that is not recovered from the heat extraction process. The unpredictable beneficial effects of the present invention can be further illustrated with reference to Figure 2, which is a comparative example of a liquid phase from an aromatic hydrocarbon. The energy is recovered in the reaction of oxidizing to form an aromatic carboxylic acid, and is referred to Fig. 3. In Fig. 2, the reaction overhead vapor from reactor 4 is introduced into a high efficiency distillation column column to the reaction column. The top vapor ηι performs a high efficiency separation. The bottom liquid stream 121 from the high efficiency steaming column 6 is returned to the reaction 4. In Fig. 2, the 'high pressure overhead gas stream 223 is introduced into a preheater 20' It is heated and prepared for oxidation treatment to decompose organic impurities in the exhaust gas. 10 The heated high pressure gas stream 229 is introduced into a catalytic oxidation treatment unit 22, in which the organic component in the heated high pressure gas stream 229 is introduced. The by-product is oxidized to a compound more suitable for environmentally friendly treatment. The oxidized high pressure gas stream 231 is directed to an expander 24 for energy recovery, and the exhaust gas 233 after the energy is withdrawn exits the expander 24. The high pressure gas stream from oxidation 231 The energy is converted to "work" in expander 15 24, and this "work is converted to electrical energy 235 by generator 26". Figure 3 illustrates the surprisingly advantageous achieved in an embodiment of the invention. Energy recovery, comparable examples compared to some other methods under similar process conditions. Examples A, B, and C present the energy recoverable from a liquid phase oxidation method of 20 For converting aromatic hydrocarbons to aromatic carboxylic acids, the stoichiometry of which consumes 2 moles of oxygen per mole of aromatic hydrocarbon, wherein the reactor is operated at about 197 ° C and about 1 6 kg/cm 2 , and wherein the acetic acid system It was used as a reaction solvent, and the liquid phase was maintained at about 14% by weight of water, and wherein the reactor overhead vapor contained about 5% by weight of oxygen. In this process, 54 1359132 performs a high efficiency separation of the reactor overhead vapor such that more than 98% by weight of the acetic acid present in the reactor overhead vapor is removed to form a high pressure overhead gas stream. The energy received in this method 'if the complete condensation of the top gas stream of the high pressure column 5 is used to extract the energy in the form of heat, and the extra energy is extracted as "work," which is the high pressure from the complete condensation. Exhaust gas (mainly containing nitrogen and other non-condensing components) undergoes further energy recovery, using an expander, in the form of "work,". The area filled in the strip represents the form in which the energy is recovered into "work" by expansion, and the 10 areas in the strip are representative of the form in which the condenser is used to recover energy to become "hot". The energy recovery achieved by the same oxidation conditions and high-efficiency separation method as the strip A is performed as shown in Fig. 2. The method of Fig. 2 does not include the heat recovery by condensation. The energy 15 is recovered into a "work" form only by introducing a high pressure overhead gas stream into an expander. The strip C represents a method of using the same oxidation conditions and high efficiency separation as the strip 8 The energy recovery achieved is if the energy recovery is carried out according to an embodiment of the invention. A comparison between the strips A and B shows that the method is carried out according to Fig. 2 or that complete condensation is used and then the uncondensed gas is expanded. The energy recovery side 20 case has a difference of less than 2% in energy recovery. According to the energy recovery of the prior art, the oxidation reactor of the aromatic carboxylic acid is formed from the liquid phase oxidation reaction of aromatic hydrocarbons. Recovering energy, the method performed in accordance with the present invention is not expected to have a significant increase in energy recovery. However, as shown by the strip C, 'I have surprisingly found that compared to the strip A, the present invention achieves Energy recovery

55 1359132 increased by more than 16%. Even though less energy is recovered from partial condensation, a surprisingly large increase in energy recovered from the expander results in greater overall energy recovery. The significantly greater energy recovery achieved by the present invention makes energy utilization 5 more efficient and results in a significant reduction in the net energy consumption of aromatic carboxylic acids from aromatic hydrocarbons. Moreover, such significantly higher energy recovery results in a significant reduction in the energy required to produce chemicals and polymer compounds derived from aromatic carboxylic acids. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of a method, which represents an embodiment of the present invention. Figure 2 represents a prior art scheme for recovering energy during liquid phase oxidation of aromatic hydrocarbons to form aromatic carboxylic acids. Figure 3 is a graph representing energy recovery based on two existing schemes compared to energy recovery in accordance with an embodiment of the present invention. 15 [Explanation of main component symbols] 4.. Reactor 6.. High-efficiency distillation column 8. Condenser 10.. Preheater 12.. Oxidation treatment single 14.. Expander 16. . Generator 20.. . Preheater 24 .. . Expander 26 .. . Generator 111.. . Pipe, reaction overhead steam 121.. bottom flow 123.. high pressure overhead flow 125··· Pipeline 127... High-pressure exhaust gas 129.. Heated high-pressure exhaust gas 22... Catalytic oxidation treatment unit 131... Oxidized high-pressure exhaust gas 56 1359132 133.. . vent gas 231.. 135...electric energy 233.· 223 .. . high pressure tower top gas stream 235.. 229.. . heating high pressure gas stream. oxidation high pressure gas stream. exhaust gas.

Claims (1)

1359132 Patent Application No. 95112111 Patent Application Revision No. 100.12.05. X. Patent Application Range: 1. A method for recovering the amount of aromatic carboxylic acid during the manufacture of aromatic carboxylic acid, the production of the aromatic acid retardant A liquid phase oxidation reaction of an aromatic hydrocarbon in which a reaction overhead vapor containing a reaction solvent and water is formed, the method comprising the steps of: η a) separating the vapor at the top of the reaction to remove at least 95% by weight of the reaction solvent present in the vapor at the top of the reaction, and forming at least one high-pressure overhead gas stream containing water and organic impurities; b) by using one The heat dissipating material is subjected to heat exchange to recover thermal energy from the high pressure overhead gas stream, such that a condensate comprising 2% to 60% by weight of water present in the high pressure overhead gas stream is formed and a condensate is present in the high pressure overhead gas stream 40 The high pressure exhaust gas to 80% by weight of water remains uncondensed; c) expanding the high pressure exhaust gas from step (b) which remains uncondensed to recover energy from the high pressure exhaust gas in the form of work. 2. The method of claim 2, further comprising the step of: oxidizing the high-pressure exhaust gas to a thermal oxidation reaction to oxidize at least a portion of the high-pressure exhaust gas before recovering the energy in the form of work Organic impurities. 3. The method of claim 1, wherein the aromatic carboxylic acid is produced by a process comprising the steps of: promoting a catalyst and a halogen in a reaction zone containing at least one reactor The oxidizing agent is used to oxidize the aromatic hydrocarbon to form an aromatic carboxylic acid in the presence of a reagent in a reaction solvent containing an eves monocarboxylic acid and in a liquid phase at a temperature ranging from 12 Torr to 25 ° C. The catalyst contains at least one atomic weight range 58 1359132 - Patent No. 9512111 Patent Application No. 100.12.05. Heavy metals in 23 to 178 form an aromatic carboxylic acid product and a reaction tower containing water and solvent vapor The overhead vapor, and comprising the steps of: a) separating at least a portion of the reaction overhead vapor to form a bottoms stream and a high pressure overhead stream, the bottoms stream comprising at least 95% by weight from the reaction column a solvent for the overhead vapor, the high pressure overhead gas stream containing at least 50% by weight of water from the removed partial reaction overhead vapor; Φ b) by means of a heat dissipating material and heat exchange with the high pressure overhead gas stream To recover energy in the form of heat, such that a condensate comprising 20% to 60% by weight of water in the high pressure overhead stream and a high pressure exhaust comprising 40 to 80% by weight of the high pressure overhead stream are maintained Not condensing; and c) expanding the high pressure exhaust gas from step (b) to maintain uncondensed to recover energy from the high pressure exhaust gas in the form of work. 4. The method of claim 3, further comprising the step of returning at least a portion of the bottoms stream to the reaction zone. 5. The method of claim 1 or 3, wherein the heat dissipating material comprises water, such that heat exchange with the high pressure overhead gas stream in step (b) produces steam. 6. The method of claim 3, wherein the Ci-Cs monocarboxylic acid solvent is acetic acid. 7. The method of claim 3, wherein the at least one heavy metal comprises a knot and one or more second metals selected from the group consisting of sputum, sputum, sputum and sputum. 8. The method of claim 7, wherein at least one heavy metal is present in the range of 100 ppm to 6000 ppmw. 9. The method of claim 7, wherein the halogen promoter is a bromine promoter. 10. The method of claim 9, wherein the bromine promoter comprises - or more selected from the group consisting of Br2, HBr, NaBr, KBr, NH4Br, benzyl bromide, bromoacetic acid, dibromoacetic acid, tetrabromoethane, A bromine compound of the group consisting of dibromoethane, bromoethane bromide, bromodeuterium and dibromoindole. 11. The method of claim 9, wherein the heat dissipating material comprises water to cause heat exchange with the high pressure overhead gas stream in step (b) to produce steam. 12. The method of claim 3, wherein the oxidation reaction is carried out at a pressure in the range of 5 to 4 〇 kg/cm2. 13. The method of claim 12, wherein the aromatic carboxylic acid is p-dicarboxylic acid. 14. The method of claim 13, wherein the aromatic hydrocarbon comprises p-xylene. 15. A device for efficiently recovering energy from a reaction overhead vapor formed during the manufacture of an aromatic carboxylic acid, the aromatic carboxylic acid being produced by liquid phase oxidation of aromatic tobacco, the apparatus comprising: a) - a reactor having a venting port for discharging the reaction overhead vapor; b) a separating element capable of separating at least 95% by weight of the reaction solvent from the reaction overhead vapor from the reactor and in fluid communication with the reactor And the element has at least one gas inlet for receiving the reaction overhead vapor from the modification of the patent application scope of the patent application No. 95, 129, 127, 127, 127, pp. a liquid; at least one liquid outlet for removing the liquid, and at least one gas outlet for removing the high pressure overhead gas stream; c) a condenser in fluid communication with the separation element, the condenser being adapted to a portion of the high pressure overhead gas stream partially condenses and exchanges heat with a heat dissipating material to extract energy from the high pressure overhead gas stream; d) - an expander in fluid communication with the condenser, the expander having at least one inlet for receiving exhaust gas containing water, and at least one outlet for discharging exhaust gas having a lower pressure than the exhaust gas. 16. The device of claim 15 wherein the separating element is one or more steaming columns. 17. The apparatus of claim 16 wherein the condenser is adapted to condense from 20% to 60% by weight of water present in the high pressure overhead gas stream. 18. The device of claim 15 further comprising a thermal oxidation unit in fluid communication with the condenser and the expander. 19. The apparatus of claim 15 wherein the condenser is further adapted to return the condensed liquid from the condenser to the separation element. 20. The method of claim 3, wherein the heat exchange with the high pressure overhead stream in step (b) is carried out in stages to produce vapors of different pressures. 21. The method of claim 3, wherein the vapor produced by the heat exchange of step (b) is directed to another portion of the method for heating. 22. The method of claim 5, wherein the heat exchange in the step (b) is in accordance with the high-pressure process of the patent application. To produce steam at different pressures. 23. The method of claim 1, wherein the heat energy extracted in step (b) is used in another portion of the method for heating. 24. The method of claim 3, wherein the energy recovered in the form of heat in the step (b) is used in another portion of the method for heating. 62 S