CN105985234B

CN105985234B - Preparation of aromatic dicarboxylic acids

Info

Publication number: CN105985234B
Application number: CN201510079767.2A
Authority: CN
Inventors: 郑东晖; 阿努伊·古普塔; 安东尼·彼得·约翰·林巴赫; 西蒙·安德鲁·沃德
Original assignee: Invista Textiles UK Ltd
Current assignee: Koch Technology Solutions UK Ltd
Priority date: 2014-10-23
Filing date: 2015-02-13
Publication date: 2021-06-01
Anticipated expiration: 2035-02-13
Also published as: WO2016062810A1; CN204714731U; CN105985234A; GB201418900D0

Abstract

The present invention provides a process for the preparation of a purified aromatic dicarboxylic acid, wherein the coolant system is configured to direct at least a portion of the second cooling liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system configured to cool the second cooling liquid if the measured temperature of the second cooling liquid downstream of the first condenser is greater than or equal to a first preset temperature and/or the measured flow rate of the second cooling liquid is less than or equal to a preset flow rate. The invention also provides a device for implementing the method.

Description

Preparation of aromatic dicarboxylic acids

Technical Field

The present invention relates to a process and an apparatus for the preparation of aromatic dicarboxylic acids.

Background

Aromatic dicarboxylic acids are typically produced by the catalytic oxidation of a hydrocarbon precursor in an organic solvent. An example is Terephthalic Acid (TA), which is widely used in the manufacture of polyesters, such as poly (ethylene terephthalate) (PET). The TA required as a reactant for PET production is known as "purified terephthalic acid" (PTA) and typically contains more than 99.97 wt.%, preferably more than 99.99 wt.% terephthalic acid, and less than 25ppm 4-carboxybenzaldehyde (4-CBA). On an industrial scale, PTA suitable for use in PET production is typically produced in a two-stage process. First, para-xylene is oxidized (e.g., using air) in the presence of a metal catalyst (e.g., cobalt and/or manganese salts or compounds) to provide "crude terephthalic acid" (CTA), as described in, for example, US 2,833,816. The CTA produced by this oxidation reaction is then purified because it is typically contaminated with impurities such as 4-CBA, p-toluic acid, and various colored impurities that impart a yellowish color to the TA. Purification of CTA typically requires at least one chemical conversion (e.g., hydrogenation) to produce PTA, in addition to at least one physical process (e.g., crystallization, washing, etc.).

PTA is generally considered a bulk commodity item with an annual production of millions of tons, and manufacturers therefore desire to reduce their cost to maximize the economics and efficiency of PTA production. This can be achieved by reducing capital costs (e.g., equipment costs) and variable costs (e.g., costs associated with waste disposal, use of starting materials, organic solvents, heating fuels, and deionized water).

In a typical commercial PTA plant, the vent gas from the oxidation reaction described above is separated in a distillation section into an organic solvent-rich liquid stream and a water-rich vapor stream. The water-rich vapor stream is condensed by transferring heat to cooling water from the auxiliary water vapor/water system of the plant, which typically produces water vapor. The CTA product stream from the oxidation reaction is passed to a crystallization section to form a CTA slurry and an overhead vapor. The overhead vapor may be condensed using a cold water feed, which may then be cooled (e.g., in a cooling tower) to dissipate the heat removed from the overhead vapor. However, dissipation of the heat removed from the overhead vapor (and the resulting losses) can be avoided by condensing the overhead vapor using a water stream from the auxiliary vapor/water system of the plant, allowing hot re-use elsewhere in the plant. In particular, the water stream may be derived in part from water vapour generated during condensation of the water-rich vapour stream.

If the oxidation reaction is shut down (e.g., due to a malfunction), the formation of overhead vapors in the crystallization section does not immediately stop. Thus, the provision of a water stream for condensing the overhead vapor must continue in a manner sufficient to provide the level of overhead vapor cooling (and thus the level of condensation required) necessary to avoid the build-up of pressure in the crystallization section that would otherwise occur, thereby potentially resulting in unsafe pressures. However, if the oxidation reaction is shut down, the generation of exhaust gases and hence water vapour during condensation of the water rich vapour stream will be reduced. This in turn reduces the flow rate of the water stream derived from the water vapor (which can be used to condense the overhead vapor from the crystallization section) and thus reduces the capacity of the plant to cool the overhead vapor.

It is an object of the present invention to provide a more economical and more efficient process for the manufacture of aromatic dicarboxylic acids, in particular a process which overcomes the aforementioned disadvantages. Further objects will be apparent from the description below.

Disclosure of Invention

The present invention provides a process for the preparation of a purified aromatic dicarboxylic acid, comprising the steps of:

i) catalytically oxidizing in an oxidation stage a hydrocarbon precursor in an organic solvent to form a product stream and an exhaust gas;

ii) separating the vent gas from the oxidation stage in a distillation stage into a liquid stream rich in organic solvent and a vapour stream rich in water;

iii) condensing the water rich vapour stream from the distillation section into a condensate stream and a vapour stream in a first condensation section by transferring heat from the water rich vapour stream to a first cooling liquid flowing in a coolant system;

iv) forming a slurry of crude aromatic dicarboxylic acid crystals and an overhead vapor from the product stream from the oxidation section in a crystallization section; and

v) purifying the crude aromatic dicarboxylic acid crystals to produce the purified aromatic dicarboxylic acid,

characterized in that the method further comprises the steps of:

vi) condensing at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid flowing in the coolant system, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid, wherein the condensing at least a portion of the overhead vapor from the crystallization section is performed in a second condensing section comprising a first condenser; and

vii) measuring the temperature of the second cooling liquid in the coolant system downstream of the first condenser and/or measuring the flow rate of the second cooling liquid in the coolant system;

wherein the coolant system is configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system configured to cool the second coolant liquid if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature and/or the measured flow rate of the second coolant liquid is less than or equal to a preset flow rate.

The present invention also provides a process for cooling overhead vapor from a crystallization section in a process for producing an aromatic dicarboxylic acid, the process comprising the steps of:

ii) separating the vent gas from the oxidation stage in a distillation stage into an organic solvent-rich liquid stream and a water-rich vapor stream;

iii) condensing the water rich vapour stream from the distillation section into a condensate stream and a vapour stream in a first condensation section by transferring heat from the water rich vapour stream to a first cooling liquid flowing in a coolant system; and

iv) forming in said crystallization section a slurry of crude aromatic dicarboxylic acid crystals and an overhead vapor from said product stream from said oxidation section,

characterized in that the method further comprises the steps of:

v) condensing at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid flowing in the coolant system, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid, wherein the condensing at least a portion of the overhead vapor from the crystallization section is performed in a second condensing section comprising a first condenser; and

vi) measuring the temperature of the second cooling liquid in the coolant system downstream of the first condenser and/or measuring the flow rate of the second cooling liquid in the coolant system;

The present invention also provides an apparatus for producing an aromatic dicarboxylic acid, comprising:

a) an oxidation stage for catalytically oxidizing a hydrocarbon precursor in an organic solvent to form a product stream and an exhaust gas;

b) a distillation section configured to separate the vent gas from the oxidation section into an organic solvent-rich stream and a water-rich vapor stream;

c) a first condensing section configured to condense the water-rich vapor stream from the distillation section into a condensate stream and a vapor stream by transferring heat from the water-rich vapor stream to a first cooling liquid flowing in a coolant system; and

d) a crystallization section configured to form a slurry of crude aromatic dicarboxylic acid crystals and an overhead vapor from the product stream from the oxidation section;

characterized in that the device further comprises:

e) a second condenser section configured to condense at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid, and wherein the second cooling liquid flows in the coolant system, wherein the second condenser section comprises a first condenser; and

f) a measuring device configured to measure a temperature of the second cooling liquid in the coolant system downstream of the first condenser, and/or a measuring device configured to measure a flow rate of the second cooling liquid in the coolant system,

In normal operation, the coolant system is suitably configured to provide the second cooling liquid to the first condenser in a manner (e.g., at a suitable temperature and at a suitable flow rate) sufficient to provide the desired level of overhead vapor cooling (and thus the desired level of condensation). The first predetermined temperature of the second cooling liquid may be a threshold above which the second cooling liquid no longer provides the desired level of overhead vapor cooling in the first condenser. Similarly, the preset flow rate of the second cooling liquid may be a threshold below which the second cooling liquid no longer provides the desired level of overhead vapor cooling in the first condenser. Thus, if the temperature and/or flow rate of the second cooling liquid is such that the second cooling liquid no longer provides the desired level of overhead vapor cooling in the first condenser, at least a portion of the second cooling liquid can be directed from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system. The feedback system is configured to cool the second cooling liquid, for example, it may include a heat exchanger configured to transfer heat away from the second cooling liquid. The temperature of the second cooling liquid that is recycled back to the first condenser is thus reduced, thereby increasing the ability of the second cooling liquid to accept heat from the overhead vapor in the first condenser. The coolant system can thus be configured to maintain the supply of the second cooling liquid to the first condenser in a manner sufficient to provide the desired level of overhead vapor cooling. The location in the coolant system downstream of the first condenser from which the second coolant is led to the location in the coolant system upstream of the first condenser is suitably located downstream of the location at which the temperature of the second coolant in the coolant system downstream of the first condenser is measured.

Preferably, the temperature of the second coolant liquid in the coolant system downstream of the first condenser is measured, and the coolant system is thus configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system configured to cool the second coolant liquid if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature, because in this configuration the coolant system increases directly in response to any measured value of the temperature of the second coolant liquid, which is indicative of under-cooling of the overhead gas.

The first and second cooling fluids are preferably water. Accordingly, water vapor is suitably generated from the first cooling liquid in the first condensation stage. The water vapor is preferably directed to a steam turbine to recover energy therefrom. Suitably the water vapour is cooled to form at least part of the second cooling liquid.

The present invention thus maintains the supply of the second cooling liquid to the first condenser in a manner sufficient to provide the desired level of cooling of the overhead vapor. In particular, the invention maintains the provision of such a second cooling liquid in the event that the oxidation stage is switched off and the water vapour produced by the first condensation stage, which ultimately forms at least part of the second cooling liquid, is thus reduced. The present invention thus allows the crystallization section to continue to operate safely after the oxidation section is shut down.

Drawings

Fig. 1 is a schematic diagram of a method and apparatus according to the present invention.

Detailed Description

Various embodiments of the invention are described herein. It is to be understood that the features specified in each embodiment may be combined with other specified features to provide further embodiments.

As used herein, "upstream" and "downstream" are set forth with respect to the direction of flow of the second cooling liquid. As used herein, at least a portion of "can refer to at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the associated stream.

It will be appreciated that the general operation of the process and apparatus for the preparation of aromatic dicarboxylic acids by catalytic oxidation of a hydrocarbon precursor in an organic solvent is well known. For example, as noted above, terephthalic acid suitable for use in PET production (i.e., purified terephthalic acid) is typically produced in a two-stage process. First, para-xylene is oxidized (e.g., using air) in the presence of a metal catalyst (e.g., cobalt and/or manganese salts or compounds) to provide crude terephthalic acid. Then, the crude terephthalic acid produced by the oxidation reaction is purified to remove impurities such as 4-CBA and p-toluic acid to produce purified terephthalic acid. The purification of crude terephthalic acid generally requires at least one chemical conversion (e.g., hydrogenation) in addition to at least one physical process (e.g., crystallization, washing, etc.).

Preparation of aromatic dicarboxylic acids

The aromatic dicarboxylic acid produced in the process and apparatus of the present invention is preferably selected from the group consisting of terephthalic acid, phthalic acid and isophthalic acid. The aromatic dicarboxylic acid is preferably terephthalic acid. Hydrocarbon precursors are compounds that can be oxidized to form aromatic dicarboxylic acids. Thus, the hydrocarbon precursor is typically substituted with a carboxylic acid such as C at the desired position in the final product_1-6Alkyl, formyl or acetyl substituted benzene or naphthalene. The preferred hydrocarbon precursor is C_1-6An alkyl-substituted benzene, specifically, p-xylene. The organic solvent is typically an aliphatic carboxylic acid, such as acetic acid, or a mixture of one or more such aliphatic carboxylic acids with water. The oxidation reaction may be carried out under any conditions in which oxygen is present, for example, the reaction may be carried out in air. The reaction catalyst typically comprises cobalt and/or manganese in soluble form (e.g. of the same)Acetate salt) using a bromine source (e.g., hydrogen bromide) as a promoter. The temperature of the oxidation reaction is typically in the range of about 100 ℃ and 250 ℃, preferably about 150 ℃ and 220 ℃. Any conventional pressure may be used for the reaction to suitably maintain the reaction mixture in the liquid state.

The oxidation stage, which typically includes an oxidation reactor, performs the function of catalytically oxidizing the hydrocarbon precursor in the organic solvent to form a product stream and an exhaust gas. The product stream is passed to a crystallization section, typically comprising one or more crystallizers, to form a slurry of crude aromatic dicarboxylic acid crystals and an overhead vapor. The slurry of crude aromatic dicarboxylic acid crystals is typically passed to a separation section where the mother liquor is separated from the crude aromatic dicarboxylic acid crystals and may then be mixed with an aqueous liquid to form a second slurry of crude aromatic dicarboxylic acid crystals. This second slurry of crude aromatic dicarboxylic acid crystals is typically passed to a purification apparatus, heated and hydrogenated, and then cooled to form a slurry of purified aromatic dicarboxylic acid crystals.

In the distillation section, the off-gas from the oxidation section is separated into a liquid stream rich in organic solvent and a vapour stream rich in water. The organic solvent-rich liquid stream from the distillation section typically comprises 80-95% w/w organic solvent and is returned to the oxidation section. The water-rich vapour stream from the distillation section typically comprises from 0.1 to 5.0% w/w organic solvent and is condensed in a first condensation section, typically comprising one or more condensers, in which heat is transferred from the water-rich vapour stream to a first cooling liquid flowing in a coolant system, to form a condensate stream and an overhead gas. A portion of the condensate stream is typically used as the source of aqueous liquid for forming the second slurry of crude aromatic dicarboxylic acid crystals described above. A portion of the condensate stream also typically forms a source of scrubbing fluid for the purified aromatic dicarboxylic acid crystals from the purification apparatus.

Overhead vapor from the crystallization section, typically containing organic solvent, a derivative of the organic solvent (e.g., methyl acetate), and water, is condensed in a second condensation section comprising a first condenser by transferring heat from the overhead vapor to a second cooling liquid flowing in a coolant system, at least a portion of the second cooling liquid being derived from the first cooling liquid, thereby forming a condensate stream and an overhead gas.

Coolant system

The coolant system is suitably configured to recover heat removed from the overhead vapour from the crystallization section so that it can be used elsewhere in the plant. For example, the coolant system may be configured to direct at least a portion of the second cooling liquid from the second condenser section to a downstream unit, such as a deaerator, which may be used to deaerate the demineralized water to make it suitable for use elsewhere in the coolant system. The coolant system may be configured to direct all of the second cooling liquid from the second condenser section to the downstream unit in normal operation (i.e. when the measured temperature of the second cooling liquid downstream of the first condenser is below a first preset temperature and the measured flow rate of the second cooling liquid is above a preset flow rate). In addition, the coolant system is also suitably configured to recover heat from the water-rich vapor stream from the distillation section as it is passed to the first cooling liquid in the first condensation section. The first cooling liquid, typically water, may be supplied to the first condensation section together with the second cooling liquid from the deaerator, optionally via one or more intermediate units. The first condensing section typically comprises one or more condensers, each of which typically receives a separate supply of the first cooling liquid, through which the water-rich vapor stream from the distillation section flows in sequence. Thus, as the water-rich vapour stream is cooled through the first condenser stage, it transfers heat to the first cooling liquid at a successively lower temperature in each successive condenser, and the water vapour generated in each successive condenser has a lower pressure than the water vapour generated in front of it. These vapors are typically fed to a steam turbine along with steam from elsewhere in the plant to recover mechanical energy therefrom. This mechanical energy may be used to generate electricity by way of a generator driven by a steam turbine that may be used elsewhere in the plant. The spent steam exiting the steam turbine may thus be passed to a turbine condenser to cool the spent steam to form a condensate, which may optionally be combined with other coolant streams to form a second cooling liquid.

The coolant system typically includes a pump that delivers the second coolant from the turbine condenser to the second condenser section, which typically maintains a constant discharge pressure of the second coolant under normal operation.

The second condensation stage comprises a first condenser wherein heat is transferred from at least a portion of the overhead vapor from the crystallization stage to a second cooling liquid. The temperature of the second coolant liquid downstream of the first condenser is measured and, if the temperature is greater than or equal to a preset temperature, the coolant system directs at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system. As mentioned above, the first predetermined temperature of the second cooling liquid may be a threshold above which the second cooling liquid no longer provides the desired level of cooling of the overhead vapor in the first condenser. The first predetermined temperature of the second cooling liquid is suitably 50 ℃, or 55 ℃, or 60 ℃, or 65 ℃, or 70 ℃, or 75 ℃, or 80 ℃, or 85 ℃. Preferably, the first preset temperature of the second cooling liquid is about 70 ℃.

The feedback system suitably comprises a heat exchanger configured to transfer heat away from the second cooling liquid, for example, the heat exchanger may be provided with a cold water feed which may optionally be subsequently used to cool the used water vapour in a turbine condenser, and then cooled (e.g. in a cooling tower) to dissipate the heat removed from the overhead vapour. Thus, the feedback system provides a means for removing heat from the overhead vapor from the plant when needed. The feedback system also suitably includes a valve that opens in response to the measured temperature of the second coolant downstream of the first condenser being greater than or equal to a first preset temperature and/or in response to the measured flow rate of the second coolant being less than or equal to a preset flow rate, thereby causing the second coolant to flow through the feedback system. The coolant system temperature control and/or flow rate control is suitably performed via a Distributed Control System (DCS) or a Programmable Logic Controller (PLC). Thus, the following steps can be performed by DSC or PLC: at least a portion of the second coolant liquid is directed from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via a feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature and/or the measured flow rate of the second coolant liquid is less than or equal to a preset flow rate. Thus, the DCS-based or PLC-based control may be configured to respond to the measured temperature of the second cooling liquid downstream of the first condenser being greater than or equal to a first preset temperature and/or the measured flow rate of the second cooling liquid being less than or equal to a preset flow rate by actuating a valve.

The second condensation section may comprise a second condenser. Thus, the temperature of the second cooling liquid in the coolant system may be measured downstream of the second condenser, e.g. by a suitably positioned measuring device, and the coolant system may further be configured to direct at least a portion of the second cooling liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the second condenser via the feedback system, if the measured temperature of the second cooling liquid downstream of the second condenser is greater than or equal to a second preset temperature. Accordingly, the valve in the feedback system is suitably opened in response to the measured temperature of the second coolant liquid downstream of the second condenser being greater than or equal to a second preset temperature. The second cooling liquid suitably flows from the first condenser to the second condenser. The location at which the temperature of the second cooling liquid in the coolant system downstream of the first condenser is measured is therefore expediently upstream of the second condenser. Typically, the second predetermined temperature is higher than the first predetermined temperature. Thus, the second predetermined temperature of the second cooling liquid is suitably 90 ℃, or 95 ℃, or 100 ℃, or 105 ℃, or 110 ℃, or 115 ℃, or 120 ℃. Preferably, the second preset temperature of the second cooling liquid is about 120 ℃. The coolant system may thus be configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature and/or the measured flow rate of the second coolant liquid is less than or equal to a preset flow rate, and the coolant system may thus be further configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to a second preset temperature. The following steps may be performed by the DCS or PLC: directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via a feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature, and directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via a feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to a second preset temperature. Accordingly, the DCS-based or PLC-based control may be further configured to respond to the measured temperature of the second coolant downstream of the second condenser being greater than or equal to a second preset temperature by actuating a valve.

Crystallization stage

The crystallization section typically comprises at least one crystallizer. In particular, the crystallization section may comprise a first crystallizer and a second crystallizer. The crystallization section may comprise one or more additional crystallizers between the second crystallizer and the oxidation section. Alternatively, the second crystallizer may receive a product stream from the oxidation stage. The crystallization section may comprise one or more further crystallizers between the first crystallizer and the second crystallizer. Typically, a slurry of crude aromatic dicarboxylic acid crystals flows from the second crystallizer to the first crystallizer via any intervening crystallizers. Accordingly, the first condenser is suitably configured to receive the overhead vapor from the first crystallizer. The second condenser, if present, is suitably configured to receive overhead vapor from the second crystallizer.

The invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a method and apparatus according to a preferred embodiment of the present invention. Oxidation reactor 10 is fed with an aqueous organic solvent, preferably aqueous acetic acid, a reaction catalyst, air and a hydrocarbon precursor, preferably p-xylene (inlet not shown). The exhaust gas 10a is passed from the oxidation reactor 10 to the distillation section 20. A liquid stream 20a rich in organic solvent is passed from the distillation section 20 to the oxidation reactor 10. The water-enriched vapor stream 20b is passed from distillation section 20 to first condensation section 30 where it is cooled by heat exchange with first coolant liquid stream 30 a. Condensate stream 30b is removed for use elsewhere in the process and apparatus.

Product stream 10b is passed to a crystallization section 80 comprising crystallizer 90 and crystallizer 100. The crystallization section 80 may include one or more additional crystallizers (not shown) between the oxidation reactor 10 and the crystallizer 90, between the crystallizer 90 and the crystallizer 100, and/or after the crystallizer 100. The overhead vapor stream 90a is passed from crystallizer 90 to condenser 92, and the condenser outlet stream 92a is removed for further processing or partially recycled to crystallizer 90. Product stream 90b is passed to crystallizer 100. The overhead vapor stream 100a is passed from crystallizer 100 to condenser 102, and the condenser outlet stream 102a is removed for further processing or partially returned to crystallizer 100. Product stream 100b is removed for further processing.

The steam 30c, which may be combined with steam from elsewhere in the process, is sent to a steam turbine 40 to recover energy from the steam. The spent water vapor 40a is passed to a turbine condenser 50 and forms a condensate stream 50 a. The cooling water stream 50b is sent to the turbine condenser 50 while the cooling water stream 50c is cooled, for example, in a cooling tower. Pump 70 delivers a second coolant stream 70a to condenser 102 to cool crystallizer overhead vapor stream 100 a. The second coolant stream 102b is passed to the condenser 92 to cool the crystallizer overhead stream 90 a. In normal operation, second coolant stream 92b is removed for further processing and use (e.g., in an auxiliary steam system).

If the temperature of the second coolant stream 102b, as measured by the temperature controller TC1, and/or the temperature of the second coolant stream 92b, as measured by the temperature controller TC2, exceeds a threshold value, the valve V1 begins to open, causing the second coolant stream 92c to flow to the heat exchanger 60, where it is cooled by the flow of cooling water 60 a. The cooling water stream 60b can be used to form the cooling water stream 50b or be cooled, for example, in a cooling tower. Second coolant stream 60c is combined with condensate stream 50a and removed to pump 70.

According to an embodiment of the present disclosure, the following is provided.

Scheme 1

A process for the preparation of a purified aromatic dicarboxylic acid, said process comprising the steps of:

characterized in that the method further comprises the steps of:

Scheme 2

A process for cooling overhead vapor from a crystallization section in a process for producing an aromatic dicarboxylic acid, the process comprising the steps of:

iv) forming in said crystallization section a slurry of aromatic dicarboxylic acid crystals and an overhead vapor from said product stream from said oxidation section;

characterized in that the method further comprises the steps of:

Scheme 3

The method of scheme 1 or scheme 2, wherein step vi) comprises measuring a temperature of the second coolant liquid in the coolant system downstream of the first condenser, and wherein the coolant system is configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

Scheme 4

The method of any of the preceding aspects, wherein the feedback system comprises a heat exchanger configured to transfer heat away from the second cooling liquid.

Scheme 5

The method of any one of the preceding aspects, wherein the first cooling fluid and the second cooling fluid are water.

Scheme 6

The method of scheme 5, wherein water vapor is generated from the first cooling liquid in the first condenser section.

Scheme 7

The method of scheme 6, wherein the water vapor is directed to a steam turbine.

Scheme 8

The method of scheme 6 or scheme 7, wherein the water vapor is cooled to form at least a portion of the second cooling liquid.

Scheme 9

The method according to any one of the preceding solutions, wherein the second condensation section comprises a second condenser, and step vi) further comprises measuring the temperature of the second cooling liquid in the coolant system downstream of the second condenser, wherein the coolant system is further configured to direct at least a portion of the second cooling liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the second condenser via the feedback system, if the measured temperature of the second cooling liquid downstream of the second condenser is greater than or equal to a second preset temperature.

Scheme 10

The method of claim 9, wherein the second cooling fluid flows from the first condenser to the second condenser.

Scheme 11

The method of claim 10, wherein the second preset temperature is higher than the first preset temperature.

Scheme 12

The method of either scheme 10 or scheme 11, wherein the coolant system is configured to, if the measured temperature of the second cooling liquid downstream of the first condenser is greater than or equal to the first preset temperature, directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system, and wherein the coolant system is further configured to, if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature, at least a portion of the second coolant liquid is directed from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system.

Scheme 13

The process of any of schemes 9-12, wherein the crystallization section comprises a first crystallizer and a second crystallizer, wherein a slurry of crude aromatic dicarboxylic acid crystals flows from the second crystallizer to the first crystallizer, and wherein

The first condenser is configured to receive overhead vapor from the first crystallizer, and the second condenser is configured to receive overhead vapor from the second crystallizer.

Scheme 14

The method according to any of the schemes 1-8, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

Scheme 15

The method according to any of the schemes 9-13, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature, and directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature.

Scheme 16

An apparatus for producing an aromatic dicarboxylic acid, the apparatus comprising:

d) a crystallization section configured to form a slurry of aromatic dicarboxylic acid crystals and an overhead vapor from the product stream from the oxidation section;

characterized in that the device further comprises:

f) a measuring device configured to measure a temperature of the second cooling liquid in the coolant system downstream of the first condenser, and/or a measuring device configured to measure a flow rate of the second cooling liquid in the coolant system;

Scheme 17

The apparatus of claim 16, wherein the apparatus comprises a measuring device configured to measure a temperature of the second coolant liquid in the coolant system downstream of the first condenser, and wherein the coolant system is configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature.

Scheme 18

The apparatus of claim 16 or claim 17, wherein the feedback system comprises a heat exchanger configured to transfer heat away from the second cooling liquid.

Scheme 19

The apparatus of any of claims 16-18, wherein the first cooling fluid and the second cooling fluid are water.

Scheme 20

The apparatus of scheme 19, wherein the first condenser stage is configured to produce water vapor from the first cooling liquid.

Scheme 21

The apparatus of scheme 20, further comprising a steam turbine configured to receive the water vapor.

Scheme 22

The apparatus of scheme 20 or scheme 21, further comprising a coolant condenser configured to cool the water vapor to form at least a portion of the second cooling liquid.

Scheme 23

The apparatus according to any of the aspects 16-22, wherein the second condensation section comprises a second condenser, and the apparatus further comprises a measuring device configured to measure a temperature of the second cooling liquid in the coolant system downstream of the second condenser, wherein the coolant system is further configured to direct at least a portion of the second cooling liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the second condenser via the feedback system if the measured temperature of the second cooling liquid downstream of the second condenser is greater than or equal to a second preset temperature.

Scheme 24

The apparatus of scheme 23, wherein the coolant system is configured such that the second cooling liquid flows from the first condenser to the second condenser.

Scheme 25

The apparatus of scheme 24, wherein the second preset temperature is higher than the first preset temperature.

Scheme 26

The apparatus of scheme 24 or scheme 25, wherein the coolant system is configured to, if the measured temperature of the second cooling liquid downstream of the first condenser is greater than or equal to the first preset temperature, directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system, and wherein the coolant system is further configured to, if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature, at least a portion of the second coolant liquid is directed from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system.

Scheme 27

The apparatus of any of schemes 23-26, wherein the crystallization section comprises a first crystallizer and a second crystallizer and is configured such that a slurry of crude aromatic dicarboxylic acid crystals flows from the second crystallizer to the first crystallizer, and wherein

Scheme 28

The apparatus according to any of the claims 16-22, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

Scheme 29

The apparatus according to any of the claims 23-27, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature, and directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature.

Furthermore, in some embodiments, the present disclosure also includes the following additional aspects.

Additional scheme 1

b) a distillation section separating the vent gas from the oxidation section into an organic solvent-rich stream and a water-rich vapor stream;

c) a first condensing section that condenses the water-rich vapor stream from the distillation section into a condensate stream and a vapor stream by transferring heat from the water-rich vapor stream to a first cooling liquid flowing in a coolant system to produce water vapor; and

d) a crystallization section for forming a slurry of aromatic dicarboxylic acid crystals and an overhead vapor from said product stream from said oxidation section;

wherein the apparatus further comprises:

e) a second condenser section to condense at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid, and wherein the second cooling liquid flows in the coolant system, wherein the second condenser section comprises a first condenser; and

f) a measuring device that measures the temperature of the second cooling liquid in the coolant system downstream of the first condenser, and/or a measuring device that measures the flow rate of the second cooling liquid in the coolant system.

Additional scheme 2

The apparatus according to additional scheme 1, wherein the crystallization section comprises one or more crystallizers.

Additional scheme 3

The apparatus of additional scheme 1, wherein the coolant system comprises a feedback system that cools the second coolant, wherein the feedback system connects a location downstream of the first condenser to a location in the coolant system upstream of the first condenser.

Additional scheme 4

The apparatus of additional scheme 3, wherein the feedback system comprises a heat exchanger that transfers heat away from the second cooling liquid.

Additional embodiment 5

The apparatus of additional aspect 3, wherein the feedback system comprises a valve.

Additional embodiment 6

The apparatus of additional aspect 1, further comprising a steam turbine that receives steam generated from the first coolant.

Additional embodiment 7

The apparatus of addition 1, further comprising a steam turbine condenser that condenses water vapor exiting the steam turbine.

Additional embodiment 8

The apparatus of additional scheme 7, wherein the coolant system comprises a pump that conveys the second coolant liquid from the steam turbine condenser to the second condenser section.

Additional embodiment 9

The apparatus according to any one of additional aspects 1 to 8, wherein the second condensation section comprises a second condenser, and the apparatus further comprises a measuring device that measures the temperature of the second cooling liquid in the cooling liquid system downstream of the second condenser, wherein the cooling liquid system further connects a location in the cooling liquid system downstream of the second condenser to a location in the cooling liquid system upstream of the second condenser via a feedback system.

Additional embodiment 10

The apparatus of additional aspect 9, wherein the second condenser is connected to the first condenser.

Additional embodiment 11

The apparatus of additional scheme 9, wherein the second condenser is downstream of the first condenser.

Additional embodiment 12

The apparatus according to any of additional aspects 1-11, wherein the crystallization section comprises a first crystallizer and a second crystallizer, and the first crystallizer is connected to the second crystallizer, wherein

The first condenser receives overhead vapor from the first crystallizer and the second condenser receives overhead vapor from the second crystallizer.

Additional embodiment 13

The apparatus according to any one of additional aspects 1 to 12, wherein the coolant system control device is implemented by a distributed control system or a programmable logic controller.

Claims

1. A process for the preparation of a purified aromatic dicarboxylic acid, said process comprising the steps of:

characterized in that the method further comprises the steps of:

vi) condensing at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid flowing in the coolant system, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid by cooling water vapor produced from the first cooling liquid in the first condensation section, wherein the condensing at least a portion of the overhead vapor from the crystallization section is conducted in a second condensation section comprising a first condenser; and

2. A process for cooling overhead vapor from a crystallization section in a process for producing an aromatic dicarboxylic acid, the process comprising the steps of:

characterized in that the method further comprises the steps of:

v) condensing at least a portion of the overhead vapor from the crystallization section by transferring heat from the overhead vapor to a second cooling liquid flowing in the coolant system, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid by cooling water vapor produced from the first cooling liquid in the first condensation section, wherein the condensing at least a portion of the overhead vapor from the crystallization section is conducted in a second condensation section comprising a first condenser; and

3. A method according to claim 1 or claim 2, wherein step vi) comprises measuring the temperature of the second coolant liquid in the coolant system downstream of the first condenser, and wherein the coolant system is configured to direct at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

4. The method of any one of the preceding claims, wherein the feedback system comprises a heat exchanger configured to transfer heat away from the second cooling liquid.

5. The method of any one of the preceding claims, wherein the first cooling liquid and the second cooling liquid are water.

6. The method of claim 5, wherein water vapor is generated from the first cooling liquid in the first condenser section.

7. The method of claim 6, wherein the water vapor is directed to a steam turbine.

8. The method according to any one of the preceding claims, wherein the second condensation section comprises a second condenser, and step vi) further comprises measuring the temperature of the second cooling liquid in the coolant system downstream of the second condenser, wherein the coolant system is further configured to direct at least a portion of the second cooling liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the second condenser via the feedback system, if the measured temperature of the second cooling liquid downstream of the second condenser is greater than or equal to a second preset temperature.

9. The method of claim 8, wherein the second cooling fluid flows from the first condenser to the second condenser.

10. The method of claim 9, wherein the second preset temperature is higher than the first preset temperature.

11. The method of claim 9 or claim 10, wherein the coolant system is configured to, if the measured temperature of the second cooling liquid downstream of the first condenser is greater than or equal to the first preset temperature, directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system, and wherein the coolant system is further configured to, if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature, at least a portion of the second coolant liquid is directed from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system.

12. The process of any one of claims 8-11, wherein said crystallization section comprises a first crystallizer and a second crystallizer, wherein a slurry of crude aromatic dicarboxylic acid crystals flows from said second crystallizer to said first crystallizer, and wherein

13. The method according to any one of claims 1-7, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

14. The method according to any of claims 8-12, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature, and directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature.

15. An apparatus for producing an aromatic dicarboxylic acid, the apparatus comprising:

characterized in that the device further comprises:

e) a second condensing section configured to condense at least a portion of the overhead vapor from the crystallizing section by transferring heat from the overhead vapor to a second cooling liquid, wherein at least a portion of the second cooling liquid is derived from the first cooling liquid by cooling water vapor produced by the first cooling liquid in the first condensing section, and wherein the second cooling liquid flows in the coolant system, wherein the second condensing section comprises a first condenser; and

16. The apparatus of claim 15, wherein the apparatus comprises a measuring device configured to measure a temperature of the second coolant liquid in the coolant system downstream of the first condenser, and wherein the coolant system is configured to direct, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to a first preset temperature.

17. The apparatus of claim 15 or claim 16, wherein the feedback system comprises a heat exchanger configured to transfer heat away from the second cooling liquid.

18. The apparatus of any one of claims 15-17, wherein the first cooling fluid and the second cooling fluid are water.

19. The apparatus of claim 18, wherein the first condenser section is configured to generate water vapor from the first cooling liquid.

20. The apparatus of claim 19, further comprising a steam turbine configured to receive the water vapor.

21. The apparatus of claim 19 or claim 20, further comprising a coolant condenser configured to cool the water vapor to form at least a portion of the second cooling liquid.

22. The apparatus of any one of claims 15-21, wherein the second condensation section comprises a second condenser, and the apparatus further comprises a measuring device configured to measure a temperature of the second coolant liquid in the coolant system downstream of the second condenser, wherein the coolant system is further configured to direct, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the second condenser if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to a second preset temperature.

23. The apparatus of claim 22, wherein the coolant system is configured such that the second cooling liquid flows from the first condenser to the second condenser.

24. The apparatus of claim 23, wherein the second preset temperature is higher than the first preset temperature.

25. The apparatus of claim 23 or claim 24, wherein the coolant system is configured to, if the measured temperature of the second cooling liquid downstream of the first condenser is greater than or equal to the first preset temperature, directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system, and wherein the coolant system is further configured to, if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature, at least a portion of the second coolant liquid is directed from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system.

26. The apparatus of any one of claims 22-25, wherein the crystallization section comprises a first crystallizer and a second crystallizer, and is configured such that a slurry of crude aromatic dicarboxylic acid crystals flows from the second crystallizer to the first crystallizer, and wherein

27. The apparatus of any one of claims 15-21, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing, via the feedback system, at least a portion of the second coolant liquid from a location in the coolant system downstream of the first condenser to a location in the coolant system upstream of the first condenser if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature.

28. The apparatus of any one of claims 22-26, wherein the following steps are performed by a distributed control system or a programmable logic controller: directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the first condenser is greater than or equal to the first preset temperature, and directing at least a portion of the second coolant liquid from a location in the coolant system downstream of the second condenser to a location in the coolant system upstream of the first condenser via the feedback system if the measured temperature of the second coolant liquid downstream of the second condenser is greater than or equal to the second preset temperature.