Method of producing aromatic carboxylic acid

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing aromatic carboxylic acid. Said method involves an oxidative step for oxidising an alkyl aromatic compound in the presence of a bromine compound to obtain an aromatic carboxylic acid; and a step for burning exhaust gas formed at the oxidation step in an incinerator. The gas obtained after burning the exhaust gas at burning temperature ranging from 450°C to 1000°C is cooled to 250°C or lower, and the time for cooling from 450°C to 250°C in the cooling process is not more than 1 second.

EFFECT: use of the present method enables to inhibit formation of bromine-containing dioxins.

11 cl, 1 tbl, 4 ex, 3 dwg

 

The technical field to which the invention relates

The present invention relates to a method of manufacturing aromatic carboxylic acid.

Background of invention

Aromatic carboxylic acids such as terephthalic acid, useful as raw materials for the synthesis of polymeric esters or the like, for Example, for the production of terephthalic acid, a typical representative of aromatic carboxylic acids, industrial use, the way in which conduct the reaction liquid-phase oxidation of p-xylene by gas containing molecular oxygen at elevated pressures. Usually the reaction liquid-phase oxidation is carried out in the oxidation reactor, applying a solvent containing an aliphatic carboxylic acid, such as acetic acid, in the presence of a catalyst based on heavy metal containing mainly cobalt or manganese, and bromine compounds.

With this method of production from the oxidation reactor is formed of exhaust gas of high pressure. This exhaust gas contains, for example, the residual oxygen; p-xylene as unreacted raw material; aliphatic carboxylic acid as solvent; carbon monoxide, esters of aliphatic carboxylic acids and methyl bromide as a by-product or the like As is but the exhaust gas released into the atmosphere, if necessary, extracting useful components and energy, removing pollutants, etc.

The bromide formed among the components of the exhaust gas from bromine compounds, used as an auxiliary catalytic means or the like, is one of the substances contributing to the thinning of the ozone layer. Accordingly, it is desirable not to produce methyl bromide in the atmosphere with the exhaust gas, preferably, removing it from the exhaust gas.

As a method of processing flue gas containing hydrogen bromide, usually spend processing by incineration. For example, offer to burn the exhaust gas summing gas containing molecular oxygen, a means of supporting combustion, etc. in the presence of a catalyst (Patent documents 1 and 2). However, the disadvantages of this method are the short service life of the catalyst and the high cost of processing the waste gas.

Therefore, a method for processing a combustion exhaust gas containing methyl bromide, with fuel in regenerative thermal oxidation furnace (Patent Document 3). In Patent Document 3 is disclosed that, according to this method, the exhaust gas can be effectively treated by incineration without the use of a catalyst.

[Patent Document 1] JP-A-2000-189753

[Patent Document 2] JP-T-2001-515576 (the Term "JP-T", ispolzuemyi this document, means a "published Japanese translation patent applications under the PCT")

[Patent Document 3] JP-A-2004-257606

Disclosure of invention

The technical problem

In recent years it has become widely known harmfulness of chlorinated dioxins; fear and harm from bromodomain dioxins, which may be formed during combustion bromodomain materials that makes it desirable control over their appearance. However, in Patent Document 3 is not paid attention to the education bromodomain dioxins during the combustion of methyl bromide, are not disclosed and conditions of the combustion needed to slow the education bromodomain dioxins, etc.

Therefore, the aim of the present invention is the treatment of combustion with simultaneous inhibition of education bromodomain of dioxins in the production method of aromatic carboxylic acids, which includes a stage of processing of combustion flue gas generated at the stage of oxidation.

In addition, usually the lower the concentration of bromide, the harder it is to achieve complete combustion and processing. In Patent Document 3 describes only the processing of combustion flue gas containing hydrogen bromide in an amount of about 30 ppm million, and not tested treatment of waste gas containing methyl bromide at concentrations of n is how many frequent./million to levels above 10 ppm million

Therefore, another objective of the present invention is the treatment of combustion exhaust gas containing methyl bromide at low concentrations, difficult to handle, in the production method of aromatic carboxylic acids, which includes a stage of processing of combustion flue gas generated at the stage of oxidation.

Technical solution

As a result of intensive research conducted by the authors of the present invention to achieve the above objectives, it was found that the above objective can be achieved through the combustion exhaust gas containing methyl bromide, in special circumstances, and thus was established the present invention.

The essence of the present invention is described as follows.

[1] method for the production of aromatic carboxylic acids, which comprises oxidizing phase oxidation of alkylaromatic compounds in the presence of bromine compounds for the preparation of aromatic carboxylic acids and stage of combustion exhaust gas generated at the stage of oxidation, in installations for the incineration, where post-combustion flue gas at the combustion temperature 450-1000°C gas after combustion is cooled to 250°C or below and cooling from 450 to 250°C. in the cooling process does not exceed 1 CE is Andy.

[2] the production Method of aromatic carboxylic acids by p. [1], where the cooling time from the burning temperature up to 250°C does not exceed 1 second.

[3] the production Method of aromatic carboxylic acids by PP. [1] or [2], where the gas after combustion is cooled heat-retaining material.

[4] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[3], where the combustion is carried out in the absence of catalyst combustion.

[5] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[4], where the installation for incineration is a regenerative thermal oxidizing the installation.

[6] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[5], where the concentration bromodomain dioxins in Gaza after cooling does not exceed 1 ng-TEK/m3in units of toxic equivalent.

[7] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[6], where the phase oxidation in a solvent based aliphatic carboxylic acid, and this method includes a stage of separation of solids and liquids, in which a suspension containing aromatic carboxylic acid, obtained in stage of oxidation, and the solvent is separated into solid and liquid, obtaining the weight of the aromatic carboxylic acid and a mother liquor, and adieu returning the mother liquor, on which at least a portion of the mother liquor is re-used at the stage of oxidation.

[8] the production Method of aromatic carboxylic acids by p. [7], where the phase oxidation reuse at least 50% by weight of the mother liquor.

[9] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[8], where the concentration of bromide in the exhaust gas does not exceed 100 ppm million by volume.

[10] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[9], where the alkylaromatic compound is p-xylene.

[11] the production Method of an aromatic carboxylic acid according to any one of paragraphs. [1]-[10], where the aromatic carboxylic acid is terephthalic acid.

Beneficial effects

According to the present invention, in the method of production of aromatic carboxylic acids, which includes a stage of processing of combustion flue gas generated at the stage of oxidation, the exhaust gas containing methyl bromide, can be processed by combustion with simultaneous inhibition of education bromodomain dioxins, so that the present invention is useful because it can be reduced adverse impact on the environment.

According to the present invention, the exhaust gas containing methyl bromide at low concentrations, can be takeeffect treated by incineration.

In addition, according to the present invention, is not required to deliver a large amount of gas containing oxygen, such as air, is not required to supply fuel for combustion and burning is possible even in the absence of a catalyst so that the exhaust gas containing methyl bromide, can be effectively treated by incineration. Therefore, the present invention is useful because it can be reduced operating costs, installation costs and energy consumption.

In addition, according to the present invention, can be ingibirovalo the formation of NOX (nitrogen oxide).

According to this, the production method of an aromatic carboxylic acid according to the present invention is very safe, does not create a large adverse impact on the environment and its cost and power consumption are low.

Brief description of drawings

Figure 1 is a process flow diagram showing an example of the processing stage exhaust gas according to the present invention.

Figure 2 is a flowchart showing an example of a method of producing terephthalic acid according to the present invention.

3 is a flowchart showing another example of the production method therephtale the Oh of the acid according to the present invention.

Explication

1: vent gas phase oxidation

2: Solvent

3: Exhaust gas absorber

4: Liquid containing extractable aliphatic carboxylic acid

5: a Liquid containing the extracted esters of aliphatic carboxylic acids

6: Exhaust gas

7: Exhaust gas incinerators

8: Exhaust gas absorber

11: Absorber high pressure

12: heat Exchanger

13: Expander gas (gas throttle)

14: Installation for burning

15: Absorber

21: Reactor oxidation

22: Separator solids and liquids

23: Installation for washing

24: Separator solids and liquids and washing machine

25: Dryer

26: Refrigerator

31: Reactor oxidation

32: Reactor additional low-temperature oxidation

33: Pump

34: Heater

35: Reactor additional high temperature oxidation

36: Evaporator instant action

37: Separator solids and liquids

38: Washing machine

39: Separator solids and liquids and washing machine

40: Dryer

41: Refrigerator reactor oxidation

42: Refrigerator reactor additional low-temperature oxidation

43: Refrigerator reactor additional high temperature oxidation

44: Chilling the nick evaporator instant action

A: p-Xylene

B: the Gas containing molecular oxygen

C: Suspension

D: the Mass of terephthalic acid

E: the mother solution

F: Mass of terephthalic acid (after washing)

G: Crude crystals of terephthalic acid

H: reusable (returnable) mother solution

J: Drain the mother liquor

K: Washing fluid

L: Waste washing liquid

M: Exhaust gas oxidation reactor (up-condensing)

N: Liquid condensate

P: Exhaust gas oxidation reactor (after condensation)

Q: reusable (returnable) aliphatic carboxylic acids and esters of aliphatic carboxylic acids

a: p-Xylene

b: the Gas containing molecular oxygen

c: Suspension

d: Suspension stage additional low-temperature oxidation

e: Suspension stage additional high temperature oxidation

f: Mass of terephthalic acid

g: mother solution

h: Weight of terephthalic acid (after washing)

i: the Crystals of terephthalic acid

j: reusable (returnable) mother solution

k: Pour out the waste mother liquor

l: Washing fluid

m: Waste washing liquid

n: Exhaust gas oxidation reactor (up-condensing)

o: Liquid condensate

p: Exhaust gas oxidation reactor (after condensation)

q:Exhaust gas reactor low temperature oxidation (up-condensing)

r: Liquid condensate

s: Exhaust gas reactor low temperature oxidation (after condensation)

t: the Exhaust gas reactor of additional high-temperature oxidation (up-condensing)

u: Liquid condensate

v: Exhaust gas reactor additional high-temperature oxidation (after condensation)

w: Exhaust gas evaporator (up-condensing)

x: Liquid condensate

y: the Exhaust gas evaporator (after condensation)

z: reusable (returnable) aliphatic carboxylic acids and esters of aliphatic carboxylic acids

The best way of carrying out the invention

The present invention relates to a method of manufacturing aromatic carboxylic acids, which includes a stage of oxidation, which alkylaromatic compound oxidizes in the presence of bromoacetamide connection, receiving an aromatic carboxylic acid, and the stage at which the exhaust gas generated at the stage of oxidation, burn in the combustion, where post-combustion flue gas at a temperature of 450-1000°C gas after combustion is cooled to 250°C or below and cooling from 450°C to 250°C at the cooling stage does not exceed 1 second.

That is, the present invention can inhibit the formation of bromodomain of dioxins oposredstvovanii exhaust gas, containing methyl bromide, in the special conditions of combustion and cooling.

The production method according to the present invention will be described in detail below. In this connection it should be pointed out that in the following description, the value of pressure means the absolute pressure and the normal pressure is usually 0,101 MPa, unless otherwise specified.

Method for the production of aromatic carboxylic acids according to the present invention includes at least a stage of oxidation, which alkylaromatic compound oxidised to produce an aromatic carboxylic acid, and the stage of processing the exhaust gas, in which the exhaust gas generated at the stage of oxidation, burn in the combustion, and preferably additionally includes a stage of separation of solids and liquids and the stage of returning the mother liquor.

Kind of aromatic carboxylic acids to which the present invention is applicable is not specifically limited, and you can specify, for example, orthophthalic acid, isophthalic acid, terephthalic acid, trimellitic acid (benzotriazolyl acid), 2,6 - or 2,7-naphthaleneboronic acid, 4,4'-biphenyldicarboxylic acid, etc. In a group of these aromatic carboxylic acids the present invention is preferably used for the production of phthalic acids (ortoft the left acids, isophthalic acid, terephthalic acid or the like), and particularly preferably be used for the production of terephthalic acid.

Alkylaromatic compound source material is also not specifically limited, and the aromatic ring may be monocyclic or polycyclic. As alkyl groups you can specify, for example, methyl group, ethyl group, n-sawn group, isopropyl group, etc.

As specific examples of alkylaromatic compounds include, for example, di - and trialkylated, di - and trialkylated and di - and trialkylsilanes. Preferred examples are m-diisopropylbenzene, p-diisopropylbenzene, o-diisopropylbenzene, cimen, m-cYmen, p-cYmen, o-xylene, m-xylene, p-xylene, trimethylbenzene, 2,6 - or 2,7-dimethylnaphthalene, 2,6-diisopropylnaphthalene, 4,4'-dimethylbiphenyl or the like Due to its high reactivity, more than all the preferred alkyl benzenes, alkylnaphthalene, alkylbiphenyls etc. having from 2 to 4 alkyl groups having from 1 to 4 carbon atoms, such as methyl group, ethyl group, n-sawn the group and the isopropyl group.

Alkylaromatic compounds may be partially oxidized. These are compounds in which the alkyl groups of alkylaromatic compounds are oxidized to the aldehyde group, acyl group, to boxilai group, hydroxyalkyl group, or the like, but they are not oxidized to such an extent to become a true aromatic carboxylic acid. Specifically, for example, can be called 4-carboxybenzene (hereinafter referred to in this document abbreviated referred to as "4CBA"), 3-methylbenzaldehyde, 4-methylbenzaldehyde, m-Truelove acid, p-Truelove acid, p-Truelove aldehyde, 3-formylbenzoate acid, 4-formylbenzoate acid, 2-methyl-6-formylation etc.

These source materials can be used individually or two or more materials can be used in combinations.

In General, as the source materials preferred xylenes (o-xylene, m-xylene and p-xylene), and particularly preferred p-xylene. When p-xylene is used as the source material, aromatic compounds having partially oxidized alkyl groups are, for example, SWA, p-Truelove aldehyde, p-tolarova acid, etc. and as an aromatic carboxylic acid to obtain terephthalic acid.

As an example of the method for the production of terephthalic acid from p-xylene as a starting material will be explained below oxidation step (I), phase separation of solids and liquid (II), the stage of returning the mother liquor (III) and stage of processing exhaust gas (IV), but the production of other aromatics is their carboxylic acids may similar production with arbitrary changes in these stages.

<oxidation step (I)>

At the stage of oxidation (I) an aromatic carboxylic acid is obtained by oxidation of alkylaromatic compounds in the presence of bromoacetamide connection. For example, you can specify that the suspension, consisting mainly of an aromatic carboxylic acid and solvent, is produced by oxidation of alkylaromatic compounds used as starting material, the solvent gas containing molecular oxygen in the oxidation reactor. In the above oxidation steps (I) above oxidation reaction (oxidation) can be carried out only once or it may be performed two or more times. When the oxidation reaction (the oxidation processing) is carried out two or more times, its conditions can be the same as the conditions of the first oxidation reaction (oxidation processing), or they can be different from the first oxidation reaction (oxidation processing).

When for the production of aromatic carboxylic acid is terephthalic acid, usually as a source material can be applied to p-xylene, but, as described above, the source material, in addition to p-xylene may contain intermediate compounds or impurities, such as p-tolarova acid, p-Truelove aldehyde or SWA. Preferably, at the stage of oxidation (I) m is it 90% by weight of p-xylene was oxidized to terephthalic acid, more preferably, if the oxidized at least 95% by mass.

Typically, the solvents are mainly aliphatic carboxylic acid. Aliphatic carboxylic acid is not specifically limited, but preferred any acid from the group comprising acetic acid, propionic acid, formic acid and butyric acid. In this connection it should be stated that the terms "contain mostly" means content not less than 60% by weight of the total solvent. Of these preferred solvents containing mainly acetic acid, due to its solubility, boiling point and ease of handling. The most preferred solvents are mixtures of acetic acid and water. Regarding the mixture of acetic acid and water, the quantity of water usually amounts to not less than 1 part by mass, and preferably not less than 5 parts by weight and usually not more than 40 parts by weight, preferably not more than 25 parts by mass, and more preferably, not more than 15 parts by weight per 100 parts by weight of acetic acid. The best reaction efficiency is possible when the amount of water relative to the amount of acetic acid does not exceed the above upper limit; for inhibiting thermal decomposition of acetic acid during the oxidation reaction, it is D. what should be not lower than the above lower limit; this makes it possible to reduce costs, which is preferable in the aspect of energy saving and efficiency.

The amount of solvent is usually not less than 100 parts by mass, and preferably not less than 200 parts by weight and usually not more than 600 parts by mass, and preferably not more than 400 parts by weight per 100 parts by weight alkylaromatic compounds used as the starting material. When the amount of solvent is not lower than the above lower limit, the concentration of the suspension obtained in the oxidation reaction, becomes satisfactory, and it is unlikely complications such as blockage of pipes. In addition, if the amount of solvent does not exceed the above upper limit, it is possible to miniaturize the equipment, which is preferable in the aspect of economy.

In addition, it is preferable to reuse the mother liquor is returned with the following phase separation of solids and liquid (II), as part of the solvents used at the stage of oxidation (I).

As a gas containing molecular oxygen, it is possible to use any gas, under the condition that the gas contains molecular oxygen; for example, you can use air, oxygen-enriched air, and oxygen diluted with an inert gas. From this the x preferred gases air, due to its low cost and practicality. The supply rate of the gas containing molecular oxygen, is usually 3 to 100 times the number of moles of molecular oxygen per alkylaromatic compound source material.

Method for the production of aliphatic carboxylic acids according to the present invention includes a stage of oxidation, which alkylaromatic compound oxidizes in the presence of bromoacetamide connection to obtain an aromatic carboxylic acid. Bromododecane connection described herein is not specifically limited, but you can specify, for example, bromide heavy metal used as a catalyst, bromoacetamide auxiliary catalytic tool or the like

At the stage of oxidation of alkylaromatic compounds typically used in the catalyst. The catalyst is not specifically limited, provided that they are capable of oxidizing alkylaromatic compound, converting it into an aromatic carboxylic acid, but is usually used compounds of heavy metals and as an auxiliary catalytic funds are used bromododecane connection. To accelerate the reaction can be used in combination with sovmestnolm tool.

As elements of heavy metals, used the x in the compounds of heavy metals, can be called, for example, cobalt, manganese, Nickel, chromium, zirconium, copper, lead, hafnium, cerium, etc. These elements can be used individually or in combinations. Particularly preferably using a combination of cobalt and manganese. As such compounds of heavy metals include, for example, acetate, nitrate, acetylacetonate, naphthenate, stearate, bromide, etc. heavy metal, and particularly preferred acetate or chloride of heavy metal.

As bromodomain compounds, used as an auxiliary catalytic means, can be called, for example, molecular bromine, hydrogen bromide, sodium bromide, potassium bromide, cobalt bromide, manganese bromide or the like, and organic bromoacetamide connection, for example, methyl, metropolit, bromoform, benzylbromide, bromelicola, dibromethane, tribromide, tetrabromide or the like, These bromoacetamide connection can also be used individually or as a mixture of two or more types.

The concentration of the catalyst is not specifically limited, provided that it is within the range capable of accelerating the oxidation reaction, but as the concentration of heavy metal in the solvent, the concentration is typically 10 ppm million or more, preferably at least 100 ppm million and, more preferably, 200 ppm million or more and usually 1000 ppm million or less, preferably 5000 ppm million or less and, more preferably 3000 ppm million or less. When the concentration of heavy metal in the solvent is at a level above the lower limit or above, the reaction rate is preferably increased. In addition, if the concentration of heavy metal in the solvent exceeds the above upper limit, can be reduced manufacturing costs and at the same time can be reduced concentration of heavy metal and bromine concentration in the liquid effluent and waste gas, which is preferable in the aspects of safety and environmental protection.

When using the catalyst on the basis of heavy metal in combination with a bromine-containing compound, the amount of the bromine atom is usually not less than 0.05 mol, preferably not less than 0.1 mol, and more preferably not less than 0.5 mol and usually not more than 10 mol, preferably not more than 7 mol and, more preferably, not more than 5 mol per 1 mol of atoms of heavy metal. When the molar ratio of compounds of heavy metal and bromoacetamide connection is in this range, the catalytic activity best way increases.

When terephthalic acid is obtained using p-xylene as a starting material, a catalyst is used, the pre is respectfully, or a compound of cobalt or a compound of manganese, or both the compound and, preferably, apply bromododecane connection as an auxiliary catalytic means. A particularly preferred combination of cobalt acetate, manganese acetate and hydrogen bromide.

When the catalyst is used a compound of cobalt, compound of manganese and bromododecane connection, the applicable amounts of these compounds are as follows. The amount of cobalt (calculated as metal) is usually not less than 10 ppm million by weight, preferably not less than 100 ppm million by weight and, more preferably, not less than 200 ppm million by weight and usually not more than 2000 ppm million by weight and preferably not more than 1000 ppm million by weight based on the solvent. The amount of manganese (calculated as metal) is usually not less than 1 part./million by weight and, preferably, not less than 5 ppm million by weight and usually not more than 1000 ppm million by weight and preferably not more than 500 ppm million by weight based on the solvent. The number of bromine (calculated as elemental bromine) is usually not less than 10 ppm million by weight and, preferably, not less than 100 ppm million by weight and usually not more than 3000 ppm million by weight and preferably not more than 2000 ppm million by weight based on the solvent.

To increase the deposits of the reaction efficiency of the oxidation reaction pressure stage of oxidation is such pressure, when mixture of solvent and starting material alkylaromatic compound retains the liquid phase at the reaction temperature or higher pressure. In this document the term "save the liquid phase" means "at least to have a liquid phase.

The pressure at the stage of oxidation is usually higher than normal pressure, preferably not less than 0.2 MPa and, more preferably, not less than 0.4 MPa and usually not more than 10 MPa, preferably not more than 7 MPa, more preferably not more than 5 MPa and, more preferably, not more than 3 MPa. When the pressure at the stage of oxidation is in this range, it is possible to control side reactions and decomposition of compounds, so can be a useful way to limit the reduction of the yield. In addition, by controlling the pressure stage of oxidation at the minimum possible level in the above range, it is possible to use a reactor having a low baristanet, and reduce the value.

The temperature of the reaction at the stage of oxidation (I) (temperature of the oxidation reaction) is usually not less than 100°C, preferably at least 140°C, more preferably not less than 150°C and, more preferably, not less than 170°C and usually not more than 300°C, preferably not more than 250°C, more preferably not more than 230°C and, more preferably, not more than 210°C. When the reaction temperature okelani what is in the above range, increases the reaction rate and can increase the output. When the temperature of the oxidation reaction is in the above range, it is possible to reduce the loss of solvent due to combustion, and, in addition, it is possible to control side reactions and decomposition of compounds, so can be a useful way to reduce the decrease in the output.

When the oxidation reaction is conducted continuously, the preferred way productivity is increased and the reaction time (average residence time) is preferably not less than 20 minutes, more preferably not less than 30 minutes and, more preferably, at least 40 minutes and preferably not more than 300 minutes, more preferably not more than 150 minutes and, more preferably, not more than 120 minutes. When the reaction time is not less than the above lower limit, the reaction can be quite advanced and can be obtained aromatic carboxylic acid having a high purity. When the reaction time is not more than the above upper limit, it is possible to reduce the loss of solvent due to combustion, and to reduce cost. In addition, it is preferable from the point of view of possible capacity reduction reactor.

The types of reactors that can be applied at the stage of oxidation (I)is not specifically limited, and can be applied traditionally known what these reactors. For example, you can use any of these reactor as a reactor with a stirrer, a bubble tower reactor, the reactor piston flow type (continuous tubular type) or the like, To improve the efficiency of the reaction is preferred hull reactors complete mixing with a stirrer. The inlet gas containing molecular oxygen, usually carried out in the lower part of the reactor.

The gas containing molecular oxygen is supplied from an inlet in the lower part of the reactor used in the oxidation of alkylaromatic compounds source material and then removed from the upper head of the reactor in the form of a gas containing a large quantity of vapor of the solvent. Then the solvent is mostly separated from the extracted gas in the condenser and the distillation tower, and the remainder is produced in the form of exhaust gas. It is advisable separated solvent partially gidrolizovat by distillation or the like and returned to the oxidation reactor. Removing water in the solvent, prevents the increase in solvent content water formed as a by-product of the oxidation reaction.

The oxygen concentration in the exhaust gas is not specifically limited, but usually it is advisable to install the concentration of about 1.0% by volume or more, preferably 1.5% by volume or more and, more preferably of 2.0% by volume or more and usually about to 8.0% by volume or less, and preferably, 7.0 percent by volume or less. The oxygen concentration in the exhaust gas, which is not lower than the above lower limit, the best way increases the efficiency of the reaction in the combustion exhaust gas, as described below (the combustion efficiency of bromide). When the oxygen concentration in the exhaust gas does not exceed the above upper limit, increases security. In addition, if the oxygen concentration in the exhaust gas is in the range between the upper limit and the lower limit of this exhaust gas can be directly put in the following regenerative thermal oxidation reactor that is preferred.

If required, at the stage of oxidation (I) according to the present invention after the above oxidation reaction can be further oxidation. Additional oxidation must carry out the oxidation reaction mixture obtained in the above oxidation reaction, by supplying a gas containing molecular oxygen, without the introduction of additional source material.

A preferred example of the additional oxidation is an additional oxidation reaction mixture at a lower temperature than the temperature of the first oxidation reaction (hereinafter in this document which is called "additional low-temperature oxidation"). Preferably, the temperature of the additional low-temperature oxidation was lower than the temperature of the first oxidation reaction of 1-20°C., more preferably below 5°C or more and, more preferably below 15°C or less. When the temperature of the additional low-temperature oxidation is in the above range, it is possible to control side reactions and decomposition of compounds. Pressure for additional low-temperature oxidation is the pressure at which the mixture in the reactor can maintain the liquid phase at least at the reaction temperature or higher pressure, and this pressure is preferably from 0.2 to 10 MPa and, more preferably, not more than 5 MPa. If the pressure at low temperature oxidation does not exceed the above upper limit, it is possible to control side reactions and decomposition of compounds, so that you can best way to inhibit the reduction of the yield. Usually prefer to pressure for additional low-temperature oxidation was lower than the pressure in the first oxidation reaction. Preferably, additional low-temperature oxidation is carried out continuously, and the reaction time is preferably from 5 to 150 minutes.

As a gas containing molecular oxygen supplied to nicotinuric REGO additional oxidation; you can use the same gas as in the first oxidation reaction. Supply rate of molecular oxygen in the calculation of the number of alkylaromatic compound source material is, preferably, not less than 1/10000 (volume ratio, and so forth herein), more preferably, not less than 1/1000 and, more preferably, not less than 1/100, and preferably not more than 1/5, and more preferably not more than 1/10 in the calculation of the feed rate of the molecular oxygen used in the first oxidation reaction.

In addition, the preferred range of oxygen concentration in the exhaust gas discharged from the additional low-temperature oxidation, and justification are the same as for the above oxidation reaction.

Another preferred example of the additional oxidation is an additional oxidation reaction mixture at a higher temperature than the temperature of the first oxidation reaction (hereinafter referred to in this document it is called "additional high temperature oxidation"). When additional high temperature oxidation of the particles of the aromatic carboxylic acid in the suspension obtained by the first oxidation reaction, is dissolved in a solvent. While the particles are oxidized intermediate Oka the amplifier (pollution, which were not oxidized to the target aromatic carboxylic acid) and high purity aromatic carboxylic acid. Preferably, the temperature of the additional high temperature oxidation is higher than the temperature of the first oxidation reaction, 1-150°C, more preferably 30°C or more and, more preferably, 50°C or more and, more preferably, 100°C or less and, more preferably, 80°C or less.

In the case where terephthalic acid is obtained with p-xylene as a starting material, the reaction temperature additional high temperature oxidation is specifically preferably not less than 235°C., more preferably not less than 240°C and, preferably, not higher than 290°C and, more preferably, not more than 280°C. When the reaction temperature additional high temperature oxidation is not lower than the above lower limit, the particles of terephthalic acid is easily dissolved and cleanliness should be increased. On the other hand, when the temperature of the reaction additional high temperature oxidation does not exceed the above upper limit, has inhibited the formation of coloring impurities.

Pressure for additional high temperature oxidation is the pressure at which the mixture in the reactor can in order to maintain the liquid phase at least at the reaction temperature, or higher pressure, and this pressure is preferably not less than 0.5 MPa, more preferably not less than 1 MPa and, more preferably, not less than 3 MPa and usually not more than 10 MPa. When the pressure in the high additional oxidation does not exceed the above upper limit, it is possible to control side reactions and decomposition of compounds, so that it is possible to reduce the decrease in the output. Usually prefer to pressure at high temperature additional oxidation was lower than the pressure in the first oxidation reaction. Preferably, additional high temperature oxidation is carried out continuously, and the reaction time is preferably from 5 to 150 minutes.

As a gas containing molecular oxygen supplied to additional low-temperature oxidation, it is possible to use the same gas as in the first oxidation reaction. Supply rate of molecular oxygen in the calculation of the number of alkylaromatic compound source material is, preferably, not less than 0,003 times the number of moles, more preferably not less than 0.01 times the number of moles and preferably not more than 0.3 times the number of moles and, more preferably, not more than 0.1 times the number of moles based on the amount of aromatic carboxylic acid in susp is nsii. If the supply of molecular oxygen not lower than the above lower limit, the effect of additional oxidation tends to increase. In addition, if the supply of molecular oxygen does not exceed the above upper limit, should be avoided combustion of the solvent with oxygen.

In addition, the oxygen concentration in the exhaust gas discharged from the additional high temperature oxidation, preferably, is low for regulating the combustion of the solvent, and the desirable range is from 0 to 0.5% by volume.

Additional oxidation can be performed two or more times. For example, additional low-temperature oxidation can be performed two or more times, or additional low-temperature oxidation and high temperature additional oxidation can be performed one or more times each, or additional high temperature oxidation can be performed two or more times. According to the present invention, additional oxidation is carried out, preferably, one or more times.

The suspension containing aromatic carboxylic acid, obtained in stage of oxidation (I), usually directed to phase separation of solids and liquid (II) after passing through an intermediate manufacturing stage, if necessary. Intermediate processing is yuusha stage is not essential, and there are two or more intermediate processing stages. As an intermediate processing stages can be called unit operations, such as cooling, heating, increased blood pressure, reduced pressure, concentration, dilution, sedimentation, addition, etc; are typically conduct crystallization or dissolution. For example, when you wish to increase the degree of extraction of the target aromatic carboxylic acid, conduct crystallization, and if you want to improve cleanliness, conduct dissolution. These intermediate processing stage is chosen arbitrarily depending on the type of the target aromatic carboxylic acid, the quality of the target product, etc.

When as an intermediate manufacturing stage, carry out the crystallization, the crystals containing aromatic carboxylic acid as the main component, usually extract, cooling the suspension in the mold under reduced pressure. The mold may be the only, but it is preferable to carry out the crystallization in the form of a multi-stage process, providing a sequence of several molds. However, if the subsequent phase separation of solids and liquid (II) is carried out at elevated pressure, there are cases when the crystallization is accompanied by a pressure drop, prefer not Provo is resolved. In this regard, it should be stated that, according to the present invention, the expression "at high pressure" or "heightened pressure" means a pressure higher than normal pressure.

<phase separation of solids and liquid (II)>

The suspension obtained by oxidation reaction, then, preferably, directed to the phase separation of solids and liquid (II) and divide by the mass of an aromatic carboxylic acid and mother liquor. Phase separation of solids and liquid (II) can be carried out either at normal pressure or at elevated pressure or at reduced pressure, but it is preferable to carry it out at normal pressure or at elevated pressure and, more preferably, in a state of heightened pressure.

When the separation of solids and liquids is carried out in condition of high pressure, you can get a detached mass, having a large internal energy, and can easily carry out drying of the mass. The pressure of the slurry in the separator, the solids and liquid is preferably not less than 0.2 MPa and, more preferably, not less than 0.3 MPa and usually not more than 5 MPa, preferably not more than 3 MPa, more preferably not more than 2 MPa, more preferably not more than 1.5 MPa, and particularly preferred is equipment, not more than 1.2 MPa. When the pressure of the slurry in the separator solids and liquids is lower pressure in the above range, baristanet separator solids and liquids can be done cheaper, making it possible to reduce the cost of installation of equipment.

The mother liquor obtained by separating solids and liquids, containing mainly solvent; and contains dissolved aromatic carboxylic acid, unreacted alkylaromatic compound, catalyst, by-products, water, etc. In this connection it should be stated that the terms "includes mainly" means "not less than 60% by weight of the total amount". In addition, the separated mass obtained by separating solids and liquids, also holds the mother liquor. Therefore, to prevent reduction of the purity of the aromatic carboxylic acid, this separated the weight it is advisable to wash. Washing-up liquid is not specifically limited, if the conditions of pressure and temperature in the separator, the solids and liquid they are in a liquid state, but usually use the same connection with the solvent used for example acetic acid or water. Because after washing the aromatic carboxylic acid is dissolved in the liquid waste to prevent loss target is obratno this aromatic carboxylic acid to extract or re-use. Reuse of waste liquid after washing can be carried out either at the stage of oxidation (I)or the intermediate technology stage or at the stage of separation of solids and liquid (II).

The amount of wash liquid is preferably not less than 0.03 times the number, more preferably not less than 0.05 times the number, and more preferably not less than 0.1 times the number and, preferably, not more than 5.0 times the number, more preferably not more than 4.0 times the quantity and, more preferably, not more than 3.0-fold amount based on the weight content of solid substances are separated in the mass. To prevent boiling of the leaching fluid, the pressure in the separator solids and liquids which enter the wash liquid preferably is higher than the vapor pressure of the rinsing fluid. The difference between the vapor pressure of the rinsing fluid and pressure in the separator, the solids and liquid in the rinsing is preferably not less than 0.01 MPa, more preferably not less than 0.02 MPa and, preferably, not more than 2.0 MPa, more preferably not more than 1.0 MPa and, more preferably, not more than 0.5 MPa.

You can apply the well-known separators, solids and liquids, but when the application is Aut preferred installation, capable as the separation of solids and liquid, and washing, these stages are simplified. As such plants include, for example, a tank with mesh basket, a sump with a solid basket, rotary vacuum filter, horizontal belt filter, rotary filter press, etc. of these devices are preferred by those who are able to carry out the separation of solids and liquids in a state of high pressure, and, specifically, the settling tank with mesh basket, cage with a solid basket and a rotary filter press.

The liquid content in the mass, is separated into solid and liquid and, if necessary, washed, is usually not more than 50 mass%, preferably not more than 30 mass%, more preferably not more than 20% by mass, and particularly preferably not more than 15% by weight and usually at least 0.5% by weight and, preferably, not less than 1 mass%. The separated mass is directed to the step of drying and receive crystals of the aromatic carboxylic acid. The obtained crystals of the aromatic carboxylic acid, if necessary, subjected to further purification process, including the stage of the hydrogenation stage of crystallization, phase separation of solids and liquids, the stage of drying, etc. and get an aromatic carboxylic acid having a higher purity.

lt; Stage return the mother liquor (III)>

The production method according to the present invention, preferably, has a stage of returning the mother liquor (III). Stage return the mother liquor (III) represents a stage of re-use part of the mother liquor obtained at the stage of separation of solids and liquid (II), by returning to the stage of oxidation (I). The mother liquor obtained at the stage of separation of solids and liquid (II)may be re-used at intermediate processing stages or on the above-mentioned phase separation of solids and liquid (II), but these stages should not be included in the stage of returning the mother liquor (III).

From research conducted by the authors of the present invention, it was found that when conducting stage return the mother liquor (III), the concentration of bromide in the exhaust gas oxidation steps (I) is reduced to values in the range from several frequent./million to ten and more frequent./million Reason of this fact is not clear, but suggest that the increase in catalytic activity in the reaction system due to return catalytic component contained in the mother solution, to the stage of oxidation (I), probably reduced as a result of decomposition of bromine compounds and education METI the bromide. In addition, through the stage of returning the mother liquor the overall process can increase the yield of aromatic carboxylic acid, which is preferable.

When the production method according to the present invention includes a stage of returning the mother liquor (III), the degree of return of the stock solution of [(mass returned to the mother liquor)/(total mass of stock solution)×100] is preferably not less than 50% by mass, and more preferably not less than 70% by weight. The higher the degree of return, the less you best way to make the concentration of bromide in the exhaust gas. The degree of return may be 100% by weight, but preferably it is not more than 95% by mass, and more preferably, not more than 90 mass%. When the degree of return is in the above range, it is possible to slow down the accumulation of impurities in the reaction system and the best way to improve the quality of the product aromatic carboxylic acid.

The mother liquor obtained at the stage of separation of solids and liquid (II), if necessary, accumulate in the tank for the mother liquor or the like and then share in return the mother liquor and the mother liquor is sent to waste, and return the mother liquor is introduced at the stage of oxidation (I). The degree of return can control is activated by throttling the mother liquor, sent to waste. The mother liquor is sent to waste, usually discarded after extraction of useful components, such as solvents, catalysts, etc.

Recycled mother liquor, preferably, return to the stage of oxidation (I) in the condition of high pressure. Specifically, for example, as a stage of oxidation (I), and phase separation of solids and liquid (II), etc. is carried out at elevated pressure, and the resulting mother liquor return to the stage of oxidation (I), maintaining the condition of high pressure. If necessary, at intermediate stages, you can re-raise the pressure of the mother liquor. As a result of this recycled mother liquor return to the stage of oxidation (I), maintaining high pressure, high temperature and high catalytic activity, so that the concentration of bromide in the exhaust gas can be made lower. In addition, you can save energy required for re-heating the mother liquor returned to the stage of oxidation (I), which is preferable.

According to this, the pressure of the recycled mother liquor is the same as the pressure on the side of the slurry in the separator, the solids and liquid, and is preferably not less than 0.2 MPa and, more preferably, the e is less than 0.3 MPa. Maintaining a high pressure returned the mother liquor, can be maintained high and the temperature returned the mother liquor. On the other hand, the pressure returned the mother liquor is usually not more than 5 MPa, preferably not more than 3 MPa, more preferably not more than 2 MPa, more preferably not more than 1.5 MPa, and particularly preferably not more than 1.2 MPa. The low pressure return stock solution makes it possible for cost-effective installation with a somewhat smaller baristanet.

<processing stage off-gas (IV)>

Next, with reference to Figure 1, explanation will be given of the preferred option implementation stage of processing exhaust gas (IV) according to the present invention.

At the stage of oxidation (I) the gas produced from the oxidation reactor, the usual way is cooled in the refrigerator, attached to the oxidation reactor. Condensates, such as solvents, drain back into the oxidation reactor, and the remaining gas is released in the form of exhaust gas 1 stage of oxidation. The refrigerator may be replaced by a distillation tower or the like, When the production method includes a stage additional low-temperature oxidation and high temperature additional oxidation gases from the reactor additional oxidation also is treated in a similar manner, and they become waste gas 1 stage of oxidation. These exhaust gases can be processed individually or can be processed together.

Components included in the exhaust gas are usually solvents, unreacted starting materials, oxygen, waste products, etc. of the Exhaust gas is usually under high pressure, and the pressure is preferably not less than 0.2 MPa and, preferably, not less than 0.4 MPa and usually not more than 5 MPa, preferably not more than 3 MPa and, more preferably, not more than 2 MPa. To remove dirt exhaust gas is usually treated by combustion in the plant for combustion and release into the atmosphere after separation and return of the various components contained therein, and energy recovery, such as pressure and heat.

When terephthalic acid is obtained with p-xylene as a starting material, the components included in the exhaust gas are aliphatic carboxylic acid, such as acetic acid, as a solvent, p-xylene as unreacted starting material; an ester of an aliphatic carboxylic acid, such as methyl acetate, methyl bromide, carbon monoxide, carbon dioxide, etc. as by-products. The content of these components in the exhaust gas is, for example, not more than 10% by volume of the mu aliphatic carboxylic acids or esters of aliphatic carboxylic acids, no more than 8% by volume of oxygen, not more than 6% by volume of the amount of carbon monoxide and carbon dioxide, not more than 25 ppm million by volume of methyl bromide, not more than 20 ppm million by volume of p-xylene, etc.

First off-gas phase oxidation of 1 is introduced into the lower part of the absorber high pressure 11, while the solvent 2 supplied from the upper part, and aliphatic carboxylic acid and its esters are dissolved and absorbed by the solvent 2 and removed from the flue gas. The design of the absorber high pressure 11 is not specifically limited, but is used in the printed column, a column with a spray irrigation, the column with irrigated walls, etc. and prefer printed column. As the solvent 2 is usually applied water.

In the upper part of absorber high pressure 11 absorbed aliphatic carboxylic acid, and esters are dissolved and absorbed absorbed aliphatic carboxylic acid in the lower part. The liquid containing the extracted esters of aliphatic carboxylic acids 5, released from the bottom of the column, and the liquid containing the extracted aliphatic carboxylic acid, 4, produced from the middle part of the column, and the off-gas absorber 3 are released from the upper head part.

When the liquid containing the extracted esters of carboxylic acids 5, the TP is to participate in a stage of oxidation (I) and re-use, support equilibrium quantity, so that, preferably, to inhibit the further side esters.

When the liquid containing the extracted aliphatic carboxylic acid 4 return to the stage of oxidation (I) and re-use can be preferably ingibirovany loss of solvent at the stage of oxidation. In addition, when the water contained in the solvent 2, it is advisable to return to the stage of oxidation (I) to carry out the dehydration solvent 2 in sulemaniyah the tower.

The exhaust gas absorber 3 still maintains a high pressure, and it is reasonable to recover and reuse the energy of this pressure. As a method of recovery can be called the method of energy recovery turbines of various types or the like after processing the waste gas combustion and method for processing exhaust gas after burning the recovery of energy from the gas orifice (gatorshield) or the like, Taking into account energy losses at the stage of processing of combustion, the latter method is preferred.

Specifically, after heating the exhaust gas at about 150-160°C. in the heat exchanger 12 energy Recuperat with gas throttle (gatorshield) 13 and released by the exhaust gas of the gas throttle (getoraclearray) 6 are processed by combustion in the plant for see the project 14. The energy recovered from the gas orifice (gatorshield) 13, is used as the source of power of the air compressor used at the stage of oxidation (I), or, if necessary, the energy can be used in the generator, so that the efficient use of energy is possible.

Because of harmful gases such as carbon monoxide, methyl bromide, are contained in the exhaust gas of the gas throttle (getoraclearray) 6, the exhaust gas produced after processing, carried out to remove contaminants. Of the components contained in the gas, are the most difficult to recycle bromide, and typically used in the combustion process in the presence or in the absence of catalyst. However, the cost of the combustion process in the presence of the catalyst is high, while the combustion in the absence of catalyst requires large amounts of energy. In addition, the lower the concentration of bromide in the exhaust gas, the more difficult is the process of complete combustion. In addition, methyl bromide, when it is subjected to the combustion process becomes bromine and hydrogen bromide, but, depending on combustion conditions, it further reacts with carbon monoxide and aromatic compound remaining after combustion, and possibly education bromodomain dioxins.

In addition, assume that the bromide in the exhaust the AZE is related to the fact, the bromide of heavy metal as a catalyst and bromododecane connection as an auxiliary catalytic tool caused side reactions with the solvent, etc. at the stage of oxidation (I).

In these circumstances, the flue gas recycle combustion in the combustion according to the present invention, and the combustion process is carried out at specific conditions.

The concentration of bromide in the exhaust gas supplied to the installation for incineration of 14, is not limited, but for off-gas oxidation steps in the production method of an aromatic carboxylic acid of this concentration is usually not more than 100 ppm million by volume, preferably not more than 50 ppm million by volume and, more preferably, not more than 29 ppm million by volume, and typically not less than 1 part./million by volume, preferably not less than 2 ppm million by volume and, more preferably, not less than 3 ppm million by volume. When the concentration of bromide in the exhaust gas is less than the above lower limit, processing, combustion becomes more difficult, but you need less processing required to remove the dirt.

In order to reduce the concentration of bromide in the exhaust gas, it is desirable to increase the catalytic activity on oxidation steps (I). Means for increasing the catalytic AK is Yunosti at the stage of oxidation (I) is not specifically limited and can be called a means for increasing the concentration of cobalt in the reaction solution, means for reducing the concentration of bromine in the reaction solution in such a way that does not deactivate the catalyst, and means for increasing the degree of reuse of the mother liquor at the stage of returning the mother liquor (III).

Of these funds, it is preferable to increase the degree of reuse of the mother liquor at the stage of returning the mother liquor (III) up to 50% by weight or more and preferably 70 mass% or more. When the degree of reuse of the mother liquor is in the above range, it becomes possible to reduce the concentration of bromide in the exhaust gas up to 29 ppm million by volume or less and up to 25 ppm million by volume or less. In addition, by optimizing the concentration of cobalt in the reaction solution, the concentration of bromine in the reaction solution and the degree of reuse of the mother liquor, it is possible to increase the concentration of bromide to 20 ppm million by volume or less and up to 15 ppm million by volume or less.

The oxygen concentration in the exhaust gas supplied to the installation for incineration of 14 is not limited, and is usually not less than 1.0% by volume, preferably at least 1.5% by volume and, more preferably, not less than 2.0% by volume and usually not more than 8,0% by volume and preferably not more than 7.0% by volume. When the concentration of the oxygen in the exhaust gas is at a level above the lower limit or greater than the burning bromide becomes easy. But when it does not exceed the above upper limit, the waste gas phase oxidation can be applied directly, which is very advantageous. In particular, when the incinerators used the following apparatus regenerative thermal oxidation good combustion can be achieved even with such exhaust gas, which has a low concentration of oxygen.

The exhaust gas can be used directly, but with appropriate dilution and concentration can be adjusted concentration of bromide and oxygen concentration.

According to the present invention, the education bromodomain dioxins inhibit specific combustion conditions and the conditions of cooling of the exhaust gas.

The temperature of the combustion exhaust gas in the combustion 14 is usually not less than 450°C, preferably at least 550°C and, more preferably, not less than 600°C and usually not more than 1000°C, preferably not more than 900°C and, more preferably, not more than 850°C. When the temperature of the combustion exhaust gas is at a level above the lower limit or above can be easily carried out complete combustion of methyl bromide and can also be ingibirovalo education bromodomain dioxins. When the temperature siganidae gas does not exceed the above upper limit, can be reduced energy costs.

Gas after combustion is cooled to 250°C or below, preferably up to 200°C or below, more preferably, up to 170°C or below and, more preferably, up to 150°C or below. According to this, the temperature of the exhaust gas incinerators 7 is not more than 250°C, preferably not higher than 200°C, more preferably not more than 170°C and, more preferably, not more than 150°C. When the temperature of the gas after combustion is in the above range, it is possible to slow down the formation of bromodomain dioxins in the gas after combustion. The lower limit of the cooling temperature of the gas after combustion (temperature exhaust gas incinerators 7 is also the same) is not limited, but preferably it is not less than 70°C and, more preferably, not less than 80°C, whereby to reduce the cooling time and save energy.

According to the present invention, during the cooling of the gas after combustion time of cooling from 450°C to 250°C does not exceed 1 second and the time of cooling from 450°C to 200°C does not exceed 1 second (according to the present invention, the time required for cooling the gas after combustion, sometimes referred to simply as "cooling period"). In addition, it is preferable that the cooling time from the combustion temperatures up to 250°C not more than 1 seconds and a cooling gap is placed from the combustion temperatures up to 200°C did not exceed 1 second. As much as possible by reducing the residence time in the temperature range of about 300°C. during the cooling of the gas after combustion, can effectively inhibit the formation of bromodomain dioxins.

Rapid cooling of the gas after combustion is not limited, and include, for example, a method of reduction of gas after combustion in contact with the cooling means, a method of reduction of gas after combustion in contact with the heat sink or heat-retaining material, the method of mixing this gas with an inert gas at a low temperature method of irrigation gas after burning water in the scrubber or the like, the method of introduction of the gas after-burning in water, etc.

According to the present invention, the concentration bromodomain dioxins in Gaza after cooling can be reduced to such a low level as 1 ng-TEK/m3or less, preferably, 0.1 ng-TEK/m3or less, more preferably of 0.01 ng-TEK/m3or less and, more preferably, to 0.007 ng-TEK/m3or less. Bromoacetamide dioxins include the isomers having the dioxin ring, and isomers having dibenzofurane ring. As examples, you can specify polybrominated dibenzo-para-dioxins (PBDDs), polybrominated dibenzofurans (PBDFs), etc. in Addition, according to the present invention, can you eyesanime way to control the concentration bromodomain of dioxins in the exhaust gas with a low concentration of bromide, complete burning which I believe is traditionally difficult and which likely bromodomain dioxins.

According to the present invention, as the method of analysis and evaluation bromodomain dioxins, after determining the amount of each isomer bromodomain dioxins according to the "Preliminary method research polypageant-para-dioxin and polybromdibenzofurans" of the Ministry of environmental protection (2002), bromoacetamide dioxins calculated as the value of the toxic equivalent (Toxic Equivalent, hereafter in this document referred to as FEC)based on the concepts described in the Reference Data 3 Report the results of a study of present conditions emissions bromodomain dioxins" (2002). That is, when the toxicity of 2,3,7,8-TCDD (tetrachlorodibenzo-p-dioxin), take a 1, the values of the toxicity of other dioxins rely strictly in units of a toxic equivalency factor Toxic Equivalent Factor, hereafter in this document referred to as "TEF") and find the total number, which is the FEC. In addition, you can also refer to "Environmental Health Criteria No. 205, polybrominated dibenzo-para-dioxins and dibenzofurans", published by the Center for Environmental Information Sciences (October 2000).

Types of installation is OK for burning for use according to the present invention is not limited and examples include the installation of direct combustion, which does not apply the catalyst combustion, catalytic combustion, in which the used catalyst combustion, regenerative thermal oxidation reactor, which apply heat storage material and the like, and you can apply any of these incinerators. The preferred regenerative thermal oxidation reactor and installation of direct combustion, suitable for high temperature incineration.

As incinerators, applicable according to the present invention, the preferred installation, the installation for the combustion of the combustion chamber and the refrigerator. Because incinerators with this design, can cool the gas directly after combustion, it is possible to prevent the formation bromodomain dioxins. Also from this point of view the preferred regenerative thermal oxidation reactor or install direct combustion.

In addition, as incinerators, according to the present invention, the preferred installation with heat-retaining material installation for burning. Using incinerators with this construction, it is possible to prevent the formation bromodomain dioxins, because these plants have excellent combustion efficiency and good stability is when the combustion temperature, and with them you can easily carry out rapid cooling.

In this connection it should be stated that the above catalyst combustion is not particularly limited, but specifically, can be called manganese oxide, copper oxide, chromium oxide, the catalyst based on palladium, platinum-based, etc., another catalyst that is resistant to Halogens, etc.

Installation of direct combustion are usually equipped with a camera pre-heating the exhaust gas furnace (combustion chamber), which can burn the waste gas in absence of the catalyst combustion, and a refrigerator, in which Recuperat heat from the flue gas after combustion. The exhaust gas is preheated in the heat exchanger chamber preheating, mix with either fuel or air or both of them in the combustion chamber during a certain time period is heated at a temperature exceeding the ignition temperature, and then oxidize and decompose and release after cooling in the refrigerator. It is advisable to use heat recovered in the fridge, preheat the exhaust gas.

Regenerative thermal oxidation reactor includes a chamber pre-heating, provided with a heat storage material filled with ceramic filler, almost eliminating heat loss, combustion chamber the La in which the process of combustion exhaust gas, preheated teploakkumuliruyushchikh material, and the camera heat recovery (refrigerator) for heat recovery gas after combustion; regenerative thermal oxidation reactor is designed to maintain the temperature in the combustion chamber even with the turned off burner. In addition, regenerative thermal oxidation reactor has a design, which can alternately reversible switch camera preheating and chamber heat recovery, varying the exhaust gas channel. For example, you can use the installation disclosed in JP-A-2002-303415.

In addition, the model is suitable for applications in which it is possible burning and cooling, you can choose from among commercially available regenerative thermal oxidation reactors, such as Regenerative Thermal Oxidizer (Dürr Company, Germany), the Rotary Regenerative Thermal Oxidizer (Chugai Ro. Co., Ltd.), Twin-tower Regenerative Thermal Oxidizer (Chugai Ro. Co., Ltd.) and Single-tower, Multi-room Regenerative Thermal Oxidizer (Chugai Ro. Co., Ltd.).

In regenerative thermal oxidation reactor exhaust gas is usually heated to the prescribed temperature thermal storage material in the chamber pre-heating and then burned in the combustion chamber. The combustion temperature can be adjusted by the amount of fuel and the quantity of combustible materials in the exhaust gas. Gas after combustion is directed into the chamber of recuperational, absorb heat of this gas within a short period of time its cool thermal storage material and the gas is released to the external space incinerators.

In regenerative thermal oxidation reactor cooling rate of the gas after combustion can be adjusted by optimizing the flow quantity of the exhaust gas and the quantity and external forms Packed thermal storage material or the like So that the cooling time of the gas from 450°C to 250°C or lower in the chamber of the heat recovery can be increased to 1 second or less and, in addition, the time of cooling from 450°C to 200°C or lower can be reduced to 1 second or less. In addition, the cooling time from the combustion temperatures up to 250° or below can be reduced to 1 second or less, additionally, the cooling from the combustion temperatures up to 200°C or lower can be reduced to 1 second or less. It is preferable to use the heat recovered in the refrigerator, for preheating the exhaust gas. As described above, the flow of exhaust gas and the release of exhaust gas after combustion can be switched by valves distribution device alternately between cameras. In recent years, regenerative thermal oxidation reactors are mainly systems with rotary valves, but they do not specifically limited is s, provided that they are consistent with the essence of the present invention.

Regenerative thermal oxidation reactors, it is advantageous that the combustion process can be carried out without the supply of oxygen from the outside even when the oxygen concentration in the exhaust gas is not more than 8,0% by volume and not more than 4.0% by volume or concentration of bromide in the exhaust gas is not more than 25 ppm million by volume or less, and not more than 15 ppm million by volume, and particularly not more than 10 ppm million by volume. In addition, regenerative thermal oxidation reactor is possible to obtain a high degree of heat recovery can significantly reduce the cost of burning and can save energy.

When burning with the use of regenerative thermal oxidation reactor to accelerate the combustion is possible to apply the above catalysts combustion or the like, but given the high temperature of combustion and reduce emissions and costs, it is preferable to carry out the combustion exhaust gas in the absence of catalysts burning.

Compared to direct combustion installations, regenerative thermal oxidation reactors have high temperature stability of the combustion, and the combustion temperature is controlled to a low temperature, and can easily be rapidly cooled, so that you can best way inhibin is to NOX (nitrogen oxide). Regenerative thermal oxidation reactors have a high technological efficiency, and can reduce the number of such facilities, thereby reducing the cost of equipment.

Components such as bromine and hydrogen bromide, usually remain in the exhaust gas of incineration 7, so it is advisable to absorb these residues by gas-liquid contact with alkalis and reducing agents in the absorber 15 and then release the gas into the atmosphere. As the alkali, preferably used sodium hydroxide, potassium hydroxide, etc. and as reducing agents, preferably used sodium sulfite, urea and the like, but are not limited to these substances. As the absorber can be applied scrubber or the like, along with a tower with a nozzle, a tower with a spray irrigation and the column with irrigated walls. The exhaust gas absorber 8 release after receiving confirmation that the gas is in a state allowing release into the atmosphere.

When terephthalic acid is obtained with p-xylene as a starting material, this terephthalic acid industrial produce in two ways - by way of the MOUTH and the way QTA, taking into account differences in the quality required and the like, and the present invention is effectively applicable to both methods. Examples of the application of this image is placed to the two processes described below.

An explanation of the way the MOUTH is given first with reference to Figure 2. If not indicated otherwise, the process conditions are the same as in the above explanation.

At the first stage of oxidation (I) p-xylene And oxidizing gas containing molecular oxygen in the oxidation reactor 21 in a solvent in the presence of a catalyst, obtaining a suspension, containing terephthalic acid and the solvent. The reaction temperature is the same as above, but in the way the MOUTH is the most preferred temperature is from 170 to 200°C.

The off-gas M reactor oxidation of the oxidation reactor 21, after condensation and separation in the refrigerator 26 condensed liquid N, containing mainly solvent, produced from the oxidation reactor 21 as flue gas R reactor oxidation and direct to the stage of processing exhaust gas (IV). Refrigerator 26 may be single-stage or multistage, and a similar separation is possible even when instead of the refrigerator 26 is used distillation column. The water content in the reaction solution is adjusted, relieving a portion of the condensed liquid N, obtained by the condensation off-gas M reactor oxidation, of the reaction system. The oxygen concentration in the exhaust gas P is usually from 1.0 to 8.0% by volume, but in the way of the MOUTH, this concentration must be nemnogone. For example, this concentration is not more than 4% by volume.

If necessary, after the oxidation reaction in the reactor 21 can be additional low-temperature oxidation. The exhaust gas produced additional low-temperature oxidation, can also be addressed at the stage of processing exhaust gas (IV). In the way of the MOUTH, the oxygen concentration in the exhaust gas produced additional low-temperature oxidation, also should be a little lower, like the main oxidation reaction.

The resulting suspension To share on the weight of terephthalic acid D and the mother liquor in the separator 22 for separating solids and liquid phase separation of solids and liquid (II), if necessary, through an intermediate manufacturing stage. If necessary, the mass of terephthalic acid D is washed with a washing liquid To the washing installation 23 and get a lot of terephthalic acid (after washing) F and liquid waste washing liquid L. As shown by the dashed line in part 2, it is possible to apply the installation of 22 to separate solids and liquids and flush installation 23 in one unit 24, capable of separating solid and liquid, and to washing.

The resulting mass is F dried in the dryer 25 and get the crude crystals of terephthalic acid G. then p is acesso for hydrogenation refining (the stage of dissolution, stage hydrogenation stage of crystallization, phase separation of solids and liquids, stage of leaching, phase drying or the like), not shown in the figure, of the crude crystals of terephthalic acid G get the crystals of terephthalic acid of high purity.

On the other hand, part stock solution E obtained at the stage of separation of solids and liquid (II), preferably, direct to the stage of oxidation (I) through the stage of returning the mother liquor (III). That is, the mother solution E, after accumulation in the tank for the mother liquor or the like, if necessary, divided into recycled mother liquor N and pour out the waste mother liquor J, and recycled mother liquor N returned to the oxidation reactor 21 through the oxidation of (I). If necessary, liquid waste washing liquid L can also be returned to the oxidation reactor 21 through the oxidation of (I).

The exhaust gas obtained at the above stages, direct to the stage of processing exhaust gas (IV) and subjected to processing.

The liquid containing the extracted aliphatic carboxylic acid 4, and the liquid containing the extracted esters of aliphatic carboxylic acids 5, obtained at the stage of processing exhaust gas (IV), can be returned to the oxidation reactor 21 and, if necessary, after about the abode in a dehydration column or the like, as reusable aliphatic carboxylic acids and esters of aliphatic carboxylic acids Q.

Next, an explanation of how QTA with reference to Figure 3. The process conditions are the same as in the above explanation, unless otherwise specified.

At the stage of oxidation (I) p-xylene oxidized gas b containing molecular oxygen in the oxidation reactor 31 in a solvent in the presence of a catalyst, obtaining a suspension, containing terephthalic acid and the solvent. The reaction temperature and pressure are the same as above, but in the way QTA most preferred conditions are 180-230°C and 1-3 MPa. At the stage of oxidation is more preferable oxidation of at least 98% para-xylene by weight.

The exhaust gas reactor of the oxidation of n from the oxidation reactor 31, after condensation and separation in the refrigerator 41 condensed liquid on containing mainly solvent, released as exhaust gas p reactor oxidation and direct to the stage of processing exhaust gas (IV). Refrigerator 41 may be single-stage or multistage, and a similar separation is possible even when instead of the refrigerator 41 apply the distillation column. The water content in the reaction solution is adjusted, relieving a portion of the condensed liquid on the obtained condensation from tamago gas n, from the reaction system. The oxygen concentration in the exhaust gas p is usually from 1.0 to 8.0% by volume, but in the way QTA this concentration should be slightly larger. For example, this concentration is not less than 4% by volume.

In the way QTA additional high temperature oxidation is carried out after the oxidation reaction in the oxidation reactor 31 at the stage of oxidation (I). At this time, it is preferable to conduct additional low-temperature oxidation reaction between the oxidation and additional high temperature oxidation. The reason for this is that terephthalic acid having a high purity can be obtained by preliminary additional low-temperature oxidation to additional high temperature oxidation.

Suspension, obtained in the oxidation reactor 31, is directed into the reactor additional low-temperature oxidation 32 and conduct additional low-temperature oxidation, optionally supplying gas b containing molecular oxygen. It is desirable that additional low-temperature oxidation was carried out continuously and the reaction time was a little shorter than the primary oxidation reaction, preferably from 5 to 90 minutes.

The exhaust gas released additional low-temperature oxidation, can also be sent out to the e to the stage of processing exhaust gas (IV). That is, the exhaust gas q reactor oxidation of the oxidation reactor 32, after condensation and separation in the refrigerator 42 condensed liquid r, containing mainly solvent, released as exhaust gas s reactor oxidation and direct to the stage of processing exhaust gas (IV). Refrigerator 42 may be single-stage or multistage, and a similar separation is possible even when instead of the refrigerator 42 apply the distillation column. In the way QTA oxygen concentration in the exhaust gas produced additional low-temperature oxidation, also should be a little more similar to the primary oxidation reaction.

In the resulting suspension d additional low-temperature oxidation usually increase the pressure by means of pump 33 and then it is heated to a prescribed temperature by the heater 34, is transferred into the reactor additional high temperature oxidation 35 and optionally oxidised to supplying gas b containing molecular oxygen. Preferably, this additional high temperature oxidation was carried out continuously and the reaction temperature was preferably from 5 to 120 minutes.

The exhaust gas released additional high temperature oxidation, can also be addressed at the stage of processing exhaust gas (IV). That is, from odasi gas t reactor oxidation of the oxidation reactor 35, after condensation and separation in the fridge 43 condensed liquid u, containing mainly solvent, released as exhaust gas v oxidation reactor and sent to the machining stage off-gas (IV). Fridge 43 may be single-stage or multistage, and a similar separation is possible even when instead of the fridge 43 used distillation column. The oxygen concentration in the exhaust gas, manufactured additional high temperature oxidation is low, but this exhaust gas can be processed at the processing stage of the flue gas (IV), combining with the exhaust gases p and s, having a high concentration of oxygen.

The resulting suspension E. additional high temperature oxidation sent to phase separation of solids and liquid (II) after her, if necessary, subjected to intermediate processing stages, and usually it is subjected to reduced pressure and cooled to the prescribed temperature and pressure in the evaporator instantaneous 36 and then divide the mass of terephthalic acid f and the mother solution g in the separator, the solids and liquid 37. Suspension e can also be subjected to the separation of solids and liquids without pressure reduction and cooling, but, for the inhibition of the decomposition of some quantity is of solvent, the temperature is still desirable to some extent be reduced by reducing the pressure and conducting cooling. In addition, when the conduct described below stage returning the mother liquor (III), preferably, the temperature returned the mother liquor does not greatly exceed the pressure and temperature of the oxidation reactor 31, so it is advisable to reduce pressure and to carry out cooling. The preferred pressure after pressure reduction is close to the preferred pressure phase separation of solids and liquid (II), as described above. In addition, gas w evaporator instant action from the evaporator instantaneous 36 released as exhaust gas from the evaporator instant action after condensation and separation in the refrigerator 44 condensed liquid x, containing mainly solvent. If necessary, the exhaust gas evaporator instant action can also be processed at the processing stage of the flue gas (IV).

If necessary, the resulting mass of terephthalic acid f is washed with a washing liquid l in the washing installation 38 and get a lot of terephthalic acid after washing h and liquid waste washing liquid m. As shown by the dashed line in part 3, you can use the installation 37 for separating solids and liquid, and wash the installation of one unit 38b 39, able to separate the solid and liquid and to washing.

If necessary, the resulting mass is h, optionally dried in the dryer 40 and receive in the form of crystals of terephthalic acid i.

On the other hand, the part of the mother liquor (g, obtained at the stage of separation of solids and liquid (II), preferably, direct to the stage of oxidation (I) through the stage of returning the mother liquor (III). That is, the mother liquor (g, after accumulation in the tank for the mother liquor or the like, if necessary, divided into recycled mother liquor j and pour out the waste mother liquor k and recycled mother liquor j returned to the oxidation reactor 31 to the stage of oxidation (I). If necessary, liquid waste washing liquid m can also be returned to the oxidation reactor 31 to the stage of oxidation (I).

The exhaust gas obtained at the above stages, direct to the stage of processing exhaust gas (IV) and subjected to processing.

The liquid containing the extracted aliphatic carboxylic acid 4, and the liquid containing the extracted esters of aliphatic carboxylic acids 5, obtained at the stage of processing exhaust gas (IV), can be returned to the oxidation reactor 31 and, if necessary, after treatment in a dehydration column or the like, as re-use what has been created aliphatic carboxylic acids and esters of aliphatic carboxylic acids z.

EXAMPLE

Hereinafter the present invention will be described specifically with reference to examples, but they are in no way limit the present invention.

The measurement method

(1) the Concentration of bromide

The concentration of bromide was measured by gas chromatographic analysis under the following conditions. Used gas chromatograph GC-14B and chromatopack C-R3A (both manufactured by Shimadzu Corporation). Used glass column having a diameter of 3 mm and a length of 5 m, and as a filler in silicone DC 550 (manufactured by SHINWA CHEMICAL INDUSTRIES, LTD.). As the carrier gas was applied nitrogen, and the flow rate was 30 ml/min

The temperature of the column during the analysis was 45°C and the detector temperature was 100°C.

(2) the Concentration bromodomain dioxins

After determining the amount of each isomer bromodomain dioxins according to the "Preliminary method research polypageant-para-dioxin and polybromdibenzofurans" of the Ministry of environmental protection (2002), the concentration bromodomain dioxins was calculated as the value of the toxic equivalent (FEC)based on the concepts described in the Reference Data 3 Report the results of a study of present conditions emissions bromodomain dioxins", (2002).

Bromoacetamide dioxins included from the career, having dioxin ring, and isomers having dibenzofurane ring.

EXAMPLES AND COMPARATIVE EXAMPLES

In the following Examples and Comparative Examples as a reactor in the oxidation reaction, including low-temperature and high-temperature advanced oxidation, was used hull reactors complete mixing with a stirrer. The pressure value was an absolute pressure.

EXAMPLE 1

In a reactor made of 1 part by weight of p-xylene, 3.35 parts by weight of a solution containing the catalyst (cobalt acetate, manganese acetate and hydrogen bromide was dissolved in acetic acid containing 14% by weight water), and 6,24 parts by weight of recycled mother liquor in the state, is substantially maintained such pressure and temperature as they were during its separation from the following installation, separation of solids and liquids were injected air, creating a 20-fold excess of molecular oxygen relative to p-xylene, and carried out the oxidation reaction at a temperature 195°C, pressure of 1.34 MPa (absolute pressure) and the reaction time (average residence time) for 60 minutes. The concentration of cobalt/manganese/bromine in the reaction solution was 300/300/1000 frequent./million by weight, respectively. The oxygen concentration in the exhaust gas was set at 5.0-7.0% as of the Yamu.

The exhaust gas from the reactor was finally cooled to a temperature of 45°C and a pressure of 1.16 MPa in multistage refrigerator, combined condensates obtained from each refrigerator part was removed, and the residue was returned to the reactor. The recoverable amount of condensation was installed so that the water concentration in the mother solution, the suspension was 10 mass%.

The suspension, containing mainly the crude terephthalic acid and the solvent was removed from the reactor of the oxidation reaction. In of 5.84 parts by weight of a suspension of the crude terephthalic acid was 2,05 parts by weight, the mother liquor was 3,79 parts by weight, the suspension concentration was 35% by mass.

This suspension (5.84 parts by weight) was continuously introduced into the reactor additional low-temperature oxidation and conducted additional low-temperature oxidation, by setting the temperature of 183°C., the pressure was 1.04 MPa and the reaction time is 30 minutes. The amount of injected air was 1/44,6 of the quantities introduced in the previous oxidation reactions. The oxygen concentration in the exhaust gas regulating air in the range from 5.0 to 7.0% by volume.

The exhaust gas from the reactor additional low-temperature oxidation was finally cooled to a temperature of 45°C and a pressure of 1.16 MPa in megastudy the m-refrigerator, the condensates obtained from each refrigerator were combined and returned to the reactor additional low-temperature oxidation.

Then, the suspension is extracted from the reactor additional low-temperature oxidation, was heated and increased its pressure; the suspension is continuously introduced into the reactor additional high temperature oxidation and conducted additional high temperature oxidation, setting the temperature to 260°C., a pressure of 5.5 MPa and a reaction time of 50 minutes. The air is introduced so that the molar ratio of molecular oxygen to terephthalic acid was 0.12. The oxygen concentration in the exhaust gas was set in the range from 0 to 0.5% by volume.

The exhaust gas from the reactor additional high temperature oxidation was finally cooled to a temperature of 45°C and a pressure of 1.16 MPa in multistage refrigerator, condensates obtained from each refrigerator were combined and returned to the reactor additional high temperature oxidation.

The suspension is extracted from the reactor additional high temperature oxidation, were subjected to decompression and evaporator instant action was cooled to achieve a range of temperature and pressure of the first reactor, and then is sent to a settling tank with mesh basket and carried out the separation of solid substances is a and the liquid, maintaining the temperature and pressure, and shared a lot of terephthalic acid and mother liquor. This mass was washed with acetic acid in the mesh part of the sump and was released from the exhaust valve; the pressure was continuously reduced to atmospheric pressure for evaporation of trapped liquid, then spent drying and received and 1.56 parts by weight of crystals of terephthalic acid.

On the other hand, the mother liquor obtained by separating the solids and liquids were separated by 35% by weight of the mother liquor sent to pour out the waste, and 65% by weight of the mother liquor for reuse, keeping the temperature and pressure, and transferred recycled mother liquor in the first reactor. Pour out the waste mother liquor, after the extraction of useful components, such as terephthalic acid, acetic acid and the catalyst was sent for reuse, and the residue is purified from impurities and released into outer space.

Exhaust gases from the reactor, the reactor additional low-temperature oxidation and high temperature reactor additional oxidation were United through the above refrigerator and processed as waste gas having a temperature of 45°C and a pressure of 1.16 MPa, at a stage of processing the exhaust gas, as shown in figure 1.

On the other hand, gas 3, representing the remainder of the flue gas leaving the upper head part of the absorber and is heated at 155°C in the heat exchanger 12. After that, the gas 3 were sent to the gas orifice (ghazarossian) 13 and used as part of the power source air compressor in the form of exhaust gas 6, which had a pressure of 0.1 MPa. The oxygen concentration in the exhaust gas 6 was 6.4% by volume and the concentration is a function of bromide was 13.7 frequent./million volume.

The exhaust gas 6 is introduced into the regenerative thermal oxidation reactor used as incinerators 14, and spent the combustion temperature of the combustion temperature in the combustion chamber) 820°C, cooling time in the cooling chamber, not exceeding 1 second, and final temperature (the temperature of the exhaust gas) 80-90°C (herein the cooling means, the cooling time of the gas after burning up to 200°C or below, the same hereinafter). Namely, the cooling time required for cooling the gas at 820°C after combustion in regenerative thermal oxidation reactor to 200°C or below, less than 1 second. In this regard, it should be stated that after increasing the temperature to the temperature of the combustion air and the fuel is not provided.

When measuring the concentration of bromide in the exhaust gas incinerators its value was at the level of the detection limit or below, i.e. was less than 0.1 ppm million by volume. The measured concentration bromodomain of dioxins in exhaust gas of incineration was at the detection limit or below, i.e. was less than 0,007 ng-TEK/m3. According to this, I suppose, what has been achieved complete combustion of methyl bromide, which was almost completely converted to bromine. The results are shown in Table 1.

Then t is the cue components of the exhaust gas incinerators, as the bromine and hydrogen bromide, were absorbed by the gas-liquid contact with an alkali and a reducing agent in the absorber 15 and the gas, after receiving confirmation of his harmless the state, was released into the atmosphere.

EXAMPLE 2

The exhaust gas 6 received from the gas throttle (getoraclearray) 13 in the same manner as in Example 1. The oxygen concentration in the exhaust gas 6 6.6% by volume, and the concentration of bromide was 13.9 frequent./million by volume (oxygen concentration and the concentration of bromide were slightly different from concentrations of Example 1 due to operational variations). The exhaust gas 6 is introduced in the same regenerative thermal oxidation reactor as in Example 1, and subjected to combustion at the combustion temperature of 600°C, cooling time, not exceeding 1 second, and an outlet temperature of 80-90°C. the Time required for cooling the gas with a temperature of 600°C after combustion in regenerative thermal oxidation reactor to 200°C or below, does not exceed 1 second. In this regard, it should be stated that after increasing the temperature to the temperature of the combustion air and the fuel is not provided.

In the result, the concentration of bromide in the exhaust gas of incinerators was 1.1 ppm million by volume. Concentration bromodomain of dioxins in the exhaust gas is stop burning was at the detection limit or below, i.e. was less than 0,007 ng-TEK/m3. According to this, I suppose, what has been achieved complete combustion of methyl bromide, which was almost completely converted to bromine. The results are shown in Table 1.

EXAMPLE 3

The exhaust gas 6, obtained from the gas throttle (getoraclearray) 13 in the same manner as in Example 1, was diluted with gaseous nitrogen, resulting in oxygen concentration was 2.0% by volume and the concentration of bromide was 4.1 ppm million by volume (the ratio of oxygen concentration to the concentration of bromide was slightly different from this ratio in Example 1 due to operational variations). The exhaust gas 6 is introduced in the same regenerative thermal oxidation reactor as in Example 1, and subjected to combustion at the combustion temperature of 820°C, cooling time, not exceeding 1 second, and an outlet temperature of 80-90°C. the Time required for cooling the gas with a temperature of 820°C. after combustion in regenerative thermal oxidation reactor to 200°C or below, does not exceed 1 second. In this regard, it should be stated that after increasing the temperature to the temperature of the combustion air and the fuel is not provided.

In the result, the concentration of bromide in the exhaust gas of incinerators was at the detection limit or below, i.e. was less than 01 frequent./million in volume. Concentration bromodomain of dioxins in exhaust gas of incineration was at the detection limit or below, i.e. was less than 0,007 ng-TEK/m3. According to this, I suppose, what has been achieved complete combustion of methyl bromide, which was almost completely converted to bromine. The results are shown in Table 1.

EXAMPLE 4

The exhaust gas 6 received from the gas throttle (getoraclearray) 13 in the same manner as in Example 1. The oxygen concentration and the concentration of bromide in the exhaust gas 6 was 6.4% and 13.7 ppm million by volume, respectively. The exhaust gas 6 is introduced in the installation of direct combustion, used as incinerators 14, and spent the combustion at the combustion temperature of 1000°C, cooling time, not exceeding 1 second, and final temperature of 180°C. That is, the cooling time required for cooling gas at a temperature of 1000°C after combustion installation for direct combustion to 200°C or below, does not exceed 1 second. In this regard, it should be stated that to maintain the temperature of combustion at 1000°C continued to provide air and fuel (heavy fuel oil).

In the result, the concentration of bromide in the exhaust gas of incinerators was at the detection limit or below, i.e. was less than 0.1 ppm million poojaa. The measured concentration bromodomain of dioxins in exhaust gas of incineration was at the detection limit or below, i.e. was less than 0,007 ng-TEK/m3. According to this, I suppose, what has been achieved complete combustion of methyl bromide, which was almost completely converted to bromine. The results are shown in Table 1.

COMPARATIVE EXAMPLE 1

The exhaust gas 6 received from the gas throttle (getoraclearray) 13 in the same manner as in Example 1. The oxygen concentration in the exhaust gas 6 ranged from 5.0 to 7.0% by volume, and the concentration of bromide was 13.2 frequent./million by volume. The exhaust gas 6 is introduced into the catalytic combustion is used as incinerators 14, and was in the process of combustion, using the oxidation catalyst based on palladium, at a temperature of combustion equal to 352°C., and outlet temperature equal to 352°C.

As a result the measured concentration of bromide in the exhaust gas of incinerators was 0.8 ppm million by volume. The measured concentration bromodomain of dioxins in exhaust gas of incineration was 120 ng-TEK/m3. The results are shown in Table 1.

After that, the exhaust gas catalytic combustion was subjected to absorption by gas-liquid contact with the alkali, and in what stenopetalum in the absorber 15.

COMPARATIVE EXAMPLE 2

The exhaust gas 6 received from the gas throttle (getoraclearray) 13 in the same manner as in Example 1. The oxygen concentration in the exhaust gas 6 ranged from 5.0 to 7.0% by volume, and the concentration of bromide was 13,0 frequent./million by volume. The exhaust gas 6 is introduced into the catalytic combustion is used as incinerators 14, in the same way as in Comparative Example 1, except that the temperature of the combustion amounted to 401°C and the outlet temperature was 401°C.

As a result the measured concentration of bromide in the exhaust gas of incinerators was at the detection limit or below, i.e. was less than 0.1 ppm million by volume. Concentration bromodomain of dioxins in exhaust gas of incineration was 31 ng-TEK/m3. The results are shown in Table 1.

Applicability in industrial conditions

According to the present invention, the exhaust gas can be treated by incineration, inhibiting the formation of bromodomain dioxins, thanks to which this method is applicable in a production environment as a production method of an aromatic carboxylic acid, which reduces the adverse impact on the environment.

Moreover, according to the us is oasea the invention, the bromide in the exhaust gas can be effectively treated by incineration, due to which this method is applicable in a production environment as a production method of an aromatic carboxylic acid, which can lower operating costs, the installation costs and energy consumption.

In addition, according to the present invention, the exhaust gas can be treated by incineration, inhibiting the formation of not only bromodomain dioxins, and aromatic compounds such as benzene and NOX (nitrogen oxide), so that this method is applicable in a production environment as a production method of an aromatic carboxylic acid, which reduces the adverse impact on the environment.

The present invention is based on Japanese patent application No. 2007-278939, filed October 26, 2007, and Japanese patent application No. 2007-278940, filed October 26, 2007, descriptions, claims, drawings and abstracts are incorporated herein by reference.

1. Method for preparation of aromatic carboxylic acids, comprising: oxidizing phase oxidation of alkylaromatic compounds in the presence of bromine compounds for the preparation of aromatic carboxylic acids and stage of combustion exhaust gas generated at the stage of oxidation, the moustache is the time for burning,
where post-combustion flue gas at the combustion temperature from 450 to 1000°C gas after combustion is cooled to 250°C or below and cooling from 450 to 250°C. in the cooling process does not exceed 1 C.

2. Method for preparation of aromatic carboxylic acid according to claim 1, where the cooling time from the burning temperature up to 250°C does not exceed 1 C.

3. Method for aromatic carbon. acid according to claim 1 or 2, where the gas after combustion is cooled heat-retaining material.

4. Method for preparation of aromatic carboxylic acid according to claim 1 or 2, where the combustion is carried out in the absence of catalyst combustion.

5. Method for preparation of aromatic carboxylic acid according to claim 1 or 2 where installation for burning is a regenerative thermal oxidizing the installation.

6. Method for preparation of aromatic carboxylic acid according to claim 1 or 2 where the concentration bromodomain dioxins in the gas after cooling is not more than 1 ng-TEK/m3in units of toxic equivalent.

7. Method for preparation of aromatic carboxylic acid according to claim 1 or 2, where the phase oxidation in a solvent based aliphatic carboxylic acid, and this method includes a stage of separation of solids and liquids, in which a suspension containing aromatic carboxylic acid, obtained in stage of oxidation, and RAS is veritel, divided into solid and liquid, obtaining the weight of the aromatic carboxylic acid and a mother liquor, and the stage of returning the mother liquor, on which at least a portion of the mother liquor is re-used at the stage of oxidation.

8. Method for preparation of aromatic carboxylic acid according to claim 7, where at the stage of oxidation reuse at least 50% by weight of the mother liquor.

9. Method for preparation of aromatic carboxylic acid according to claim 1 or 2, where the concentration of bromide in the exhaust gas does not exceed 100 million-1volume.

10. Method for preparation of aromatic carboxylic acid according to claim 1 or 2, where the alkylaromatic compound is p-xylene.

11. Method for preparation of aromatic carboxylic acid according to claim 1 or 2, where the aromatic carboxylic acid is terephthalic acid.



 

Same patents:

Combustion chamber // 2462662

FIELD: power industry.

SUBSTANCE: combustion chamber includes a pipe closed on one end with a cover with combustible gas mixture supply branch pipe, diaphragm with holes, which is installed in the pipe on the side of its covered end, neck connected to the pipe on the side of its open end, and ignition plug mounted in pipe wall after diaphragm in gaseous flow movement direction. Pipe is equipped with air supply nozzle mounted in the wall in the section between diaphragm and neck, to which annular pipe which is coaxially installed in the pipe and provided with perforations made on concave wall and facing the pipe centre is connected.

EFFECT: higher heat release velocity from burnt combustible gas mixture to combustion chamber walls.

1 dwg

Afterburner chamber // 2447364

FIELD: power industry.

SUBSTANCE: afterburner chamber of combined-cycle plant is installed in transitional gas flue connecting gas turbine exhaust with waste heat boiler. Chamber contains several orders of flame tube heads of diffusion stabilising type, including angle stabilisers or gas collectors with fuel feed spray injectors located inside them. Flame tube heads are assembled of modules on top of which there are transversal angle bars inclined to output side spaced with pitch equal to distance between burner units. Transversal angle bars have shot fuel collectors in-between, which are connected with main collector. Flame tube heads arranged along the chamber length. Burner unit is the first unit installed upstream in the centre of afterburner chamber; it should be switched on first of all at start-up.

EFFECT: provision of temperature field uniformity before heat exchanger within all range of loads, reduction of hydraulic losses in gas flue, reduction of labour and installation content.

3 dwg

FIELD: chemistry.

SUBSTANCE: method involves burning a mixture of chlorine-containing organic substances in the first zone of a three-zone reactor at temperature 3500°C and pressure P=106 Pa. The products of combustion and decomposition of chlorine-containing organic substances, steam from cooling water and hardening liquid are then mixed in an agitator while lowering temperature of the mixture to 1200°C. Said mixture is held in the second zone of the reactor for 1 ms. After the second hardening step at the boundary of the second and third zones, the mixture is held in the third zone until complete evaporation of the hardening liquid and then output therefrom through a critical nozzle into a condenser. The water condensate of said vapour-gas mixture is neutralised with soda to obtain sodium chloride as a commercial product. The device for realising said method is described.

EFFECT: high efficiency of thermal decontamination of chlorine-containing organic substances.

8 cl, 1 tbl

FIELD: power industry.

SUBSTANCE: thermal processing device of organic materials includes bath from heat-conducting material, which has bottom part and inner wall, and outer wall from insulating material; at that, the above walls restrict the passage; arch covering the above bath and forming together with the above inner wall the chamber for technological processing at least with one access hole through which the above organic materials can be added to the above chamber; furnace opening to the above passage and supporting the flame, adapted for generation of gaseous combustion products circulating through the above passage for heating of the above organic material through inner wall; the first channel passing between the above chamber and the above furnace for transfer of gases evolved from organic materials to the flame; the second channel passing between chamber and external side of the above device for introduction of fresh air to chamber; mixer arranged inside the above chamber; heat exchanger connected to the above passage and to the above second channel; at that, the above heat exchanger is located inside the above chamber. Method of thermal processing of organic materials is described.

EFFECT: removal of odours at reduction of labour costs and power consumption for processing of organic materials.

8 cl, 3 dwg

FIELD: power industry.

SUBSTANCE: combustion device of chlorine-containing gases and liquids, namely of gasification and pyrolysis products of wastes, includes combustion chamber, regenerator and air supply and combustion products outlet units. Combustion chamber includes two parts separated between each other with partition and interconnected for passage of gases between them. Heat exchanger has the possibility of its being filled with gas or liquid and contains two parts that are located from above of each of two above parts of combustion chamber. Above each of the above parts of heat exchanger there located are two cavities; some of the above cavities are located above low-temperature sections of heat exchanger, and the others are located above high-temperature sections. In each cavity located above high-temperature section of heat exchanger there is high-temperature filter and regenerative packing. Each of the above cavities located above high-temperature or low-temperature sections of heat exchanger is connected to air supply and combustion products discharge units so that when the cavity located above high-temperature section of one of the parts of heat exchanger is connected to air supply unit, the cavity located above low-temperature section of the same part of heat exchanger and the cavity located above high-temperature section of the other part of heat exchanger are connected to combustion products discharge unit. Device includes supply assembly of burned gases or liquids, which is located between parts of combustion chamber.

EFFECT: use of additional fuel is avoided and quick cooling is provided in order to avoid reduction of dioxins.

5 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to chemistry and is meant for after-burning tail gases from Claus units. The device for after-burning gases has a vertical cylindrical vessel 9, lined inside with refractory material 10, a furnace chamber 1, a reaction chamber 7, an annular chamber for distributing the gas to undergo after-burning 4, whose top part is fitted with an inlet nozzle 6 and has rows of gas discharge holes in the top 5 and bottom part 11 of the furnace chamber 1. Presence of chamber for distributing the gas to undergo after-burning 4 enables feeding the said gas through the top row of gas discharge holes 5 into the top part of the furnace chamber 1, where this portion is mixed with flue gases from the burner and is heated to burning point of combustible components of the said gas, thus after-burning the said components. Heat from combustion of the components of the gas goes to heating the remaining portion of the gas to undergo after-burning in the bottom part of the furnace chamber 1.

EFFECT: invention reduces fuel consumption, increases reliability and service life.

1 dwg

FIELD: heating.

SUBSTANCE: invention refers to chemical, oil and gas and processing industries, and can be used for combustion of waste gas at factories. Device for forced combustion of waste gas includes Venturi tube with gas supply tube with conical outlet, which is installed in it coaxially and forms an annular gap in Venturi tube neck. Gas supply tube is equipped with the bell covering Venturi tube neck. On the bell a cone with cross cuts is installed. Venture tube is two-walled, hollow, and annular gap of which is installed on ventilation torus-duct. At that, internal wall of Venturi tube is provided with cross cuts offset relative to cross cuts of cone of gas supply tube as per the comb scheme. Ventilation torus-duct is connected to distribution tubes of ventilation header having normally open shutters and connection pipe for connection of forced-draft fans.

EFFECT: increasing combustion efficiency of waste gas in open atmosphere, and reduction of hazardous emissions of incomplete combustion.

FIELD: heating.

SUBSTANCE: portal of flare pipe includes gas-intake pipe and stabiliser of flame in the form of hollow geometric body, installed on top end of gas-intake pipe. Additionally stabiliser is located co-axial outside the gas-intake pipe. Under stabiliser it is co-axial and with gap is installed sleeve with central and peripheral holes in bottom, herewith by central opening sleeve is fixed on gas-intake pipe, and into peripheral hole it is built-in piston acoustic air pump.

EFFECT: reliability and effectiveness growth of burning gases combustion.

4 cl, 1 dwg

Boiler-utiliser // 2365818

FIELD: chemistry.

SUBSTANCE: boiler-utiliser is intended for neutralisation and utilisation of smoke gas heat and can be used in coke-chemical, metallurgical, chemical and other branches of industry. Boiler-utiliser contains joining pipe for smoke gas supply, joining pipe for smoke gas output, reactor supplied with cyclone combustion chamber, including burner device, into which tangentially joining pipe for smoke gas supply is joined, system of heat utilisation, which includes heat-exchanging surfaces and is connected with reactor and joining pipe for smoke gas output. Boiler-utiliser is supplied with system of enriching smoke gases with fuel and air, which is connected with joining pipe for smoke gas supply. Reactor additionally contains at least one cyclone combustion chamber and is supplied with chamber of after-burning connected with cyclone combustion chambers and forming together with them working volume of reactor, ratio of after-burning chamber volume to working volume of reactor being determined by the following dependence: 0.43<V1/V2≤0.85, where V1 is after-burning chamber volume, m3; V2 is working volume of reactor, m3.

EFFECT: ensuring high degree of smoke gas purification from admixtures, as well as increase of reliability of boiler-utiliser work and efficiency of utilisation of heat of smoke gases released from fuel-burning aggregates.

12 cl, 10 dwg, 2 tbl

FIELD: technological processes.

SUBSTANCE: invention may be used for reduction of poisonous exhausts of combustion products generated in process of fossil fuel burning. Method for reduction of combustion products in exhaust gases includes re-burning of exhaust gases prior to their outlet into environment. Exhaust gases are supplied into radiation reactor of combustion that comprises radiation chamber of combustion and facilities for energy supply into radiation chamber of combustion. Radiation reactor of combustion prevents transformation of supplied energy into radiation energy radiated into radiation chamber of combustion. Exhaust gases are exposed to effect of radiation energy in radiation reactor of combustion for increase of temperature of exhaust gases up to value sufficient for provision of spontaneous ignition. Device is also suggested for reduction of combustion products, as well as system including device for fuel burning and device for treatment of exhaust gases.

EFFECT: removal of poisonous components from exhaust gases and increase of efficiency of carbon particles burning.

44 cl, 18 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of processing polyethylene terephthalate wastes. The method involves ethanolysis of polyethylene terephthalate (PET), in which material containing PET reacts with ethanol. Ethylene glycol and an aromatic diethyl ester, such as diethyl isophthalate and/or diethyl terephthalate, are separated. PET or a terpolymer containing a terephthalate monomer and ethylene glycol monomers react with ethanol and ethanol, diethyl terephthalate, ethylene glycol and optionally diethyl isophthalate are separated. The separated diethyl components can undergo liquid-phase oxidation to obtain an aromatic carboxylic acid. Acetic acid can also be obtained via liquid-phase oxidation of the separated diethyl components. Aromatic carboxylic acid can be used to obtain polymers. The invention also describes apparatus for processing polyethylene terephthalate wastes. The apparatus includes a reactor, a distillation column operating at atmospheric pressure and a vacuum distillation column.

EFFECT: high efficiency of the method.

29 cl, 1 dwg, 8 tbl, 8 ex

FIELD: chemistry.

SUBSTANCE: method of producing a polycarboxylic acid composition involves: (a) oxidation of a multiphase reaction medium containing an oxidisable starting aromatic compound, a solvent and water, in a primary oxidation zone to obtain a starting suspension containing crude terephthalic acid; (b) oxidative combustion of at least a portion of said starting suspension in a combustion zone to obtain a combustion product suspension having one or more of the following characteristics: (i) contains less than 9000 ppm isophthalic acid; (ii) contains less than 15000 ppm benzoic acid, (iii) contains less than 64 ppm 4,4'-dicarboxybiphenyl, (iv) contains less than 70 ppm 2,6-dicarboxyfluorenone, (v) contains less than 12 ppm 2,7-dicarboxyfluorenone, (vi) contains less than 12 ppm 9-fluorenone-2-carboxylic acid, (vii) contains less than 4 ppm 4,4'-dicarboxystilbene, (viii) contains less than 6 ppm 4,4'-dicarboxyanthraquinone; (c) cooling at least a portion of said combustion product suspension in a cooling zone to obtain a cooled suspension containing cooled liquid and solid phases; and (d) using the solvent cleaning system to remove at least one aromatic impurity containing benzoic acid, para-toluic acid, 4-carboxy-benzaldehyde and/or trimellitic acid, present in the solvent cleaning charge, fed into said solvent cleaning system, where said cooled liquid phase of said cooled suspension forms at least 20 wt % of said solvent cleaning charge.

EFFECT: invention discloses systems for more efficient and cheap production of polycarboxylic acid.

112 cl, 30 dwg, 4 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing crude terephthalic acid for use at a hydrogenation purification step via liquid-phase oxidation with an oxygen-containing gas in an oxidation reactor fitted with a mixer, using as the starting material para-xylene in a solvent - acetic acid, in the presence of a metal-containing catalyst which contains cobalt (Co), manganese (Mn) and bromine (Br) as an oxidation promoter, where the oxidation reaction temperature is controlled such that is lies in the interval from 185 to 197°C, average dwell time of the starting mixture in the reactor for liquid-phase oxidation ranges from 0.7 to 1.5 hours, content of water in the reaction solvent is controlled such that it ranges from 8 to 15 wt %, and the composition of the catalyst in the solvent is controlled in a range defined depending on the reaction temperature such that it includes: (1) a catalytically active metal (Co+Mn) in amount of 2650 ppm or less and in amount equal to or more than a value determined by the following relationship: (Co+Mn) = -0.460(t-185)3+18.4(t-185)2-277.5(t-185)+2065, in which (Co+Mn) is the content of (Co+Mn) in ppm, t is the reaction temperature (°C) (temperature range from 185 to 200°C), (2) weight ratio Mn/Co is controlled in a range from 0.2 to 1.5, preferably from 0.2 to 1; (3) content of Br is equal to or less than 1.7, if represented by a value Br/(Co+Mn) in form of weight ratio, and in amount equal to or greater than a value given by the equation: Br/Mn = -0.00115(t-185)3+0.0362(t-185)2-0.5803(t-185)+5.18, in which Br/Mn is weight ratio Br/Mn (wt/wt), and t is reaction temperature (°C) (temperature range from 185 to 200°C), and crude terephthalic acid is obtained with content of 4-carboxybenzaldehyde in amount from 2000 to 3500 ppm as an intermediate product of liquid-phase oxidation. The method provides cheap production of crude terephthalic acid for use in hydrogenation purification and use of a controlled amount of oxidation catalyst, which does not have undesirable effect on the life of a hydrogenation purification catalyst, as well as conditions for carrying out the corresponding reaction.

EFFECT: obtaining terephthalic acid during liquid-phase oxidation of the corresponding dialkylated aromatic hydrocarbon using a solvent, acetic acid, carried out by reducing the oxidised amount of acetic acid lost during oxidation, limiting formation of ash in the obtained terephthalic acid, and enabling control of the composition of the oxidation catalyst depending on reaction temperature.

12 tbl, 7 dwg, 15 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of producing a composition of aromatic dicarboxylic acid, involving (a) oxidation of a multiphase reaction medium in a primary oxidation reactor to obtain a first suspension; (b) further oxidation of at least a portion of said first suspension in a secondary oxidation reactor which is of the bubble column type, wherein the method further involves feeding an aromatic compound into said primary oxidation reactor, where at least about 80 wt % of said aromatic compound fed into said primary oxidation reactor is oxidised therein, wherein head gases are moved from the top of the secondary oxidation reactor into the primary oxidation reactor. Disclosed are an optimised process and equipment for more efficient and cheaper liquid-phase oxidation. Such liquid-phase oxidation is carried out in a bubble column type reactor which ensures a highly efficient reaction at relatively low temperatures. When the oxidised compound is para-xylene and the oxidation reaction product is crude terephthalic acid (TPA), such a product, TPA, can e purified and extracted using cheaper methods than when TPA is obtained using the conventional high-temperature oxidation process.

EFFECT: improved method of producing a composition of aromatic dicarboxylic acid.

30 cl, 4 tbl, 31 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to improved methods of producing aromatic carboxylic acids, involving bringing material containing at least one initial substituted aromatic hydrocarbon, where the substitutes are oxidisable to carboxylic acid groups, with oxygen gas in a liquid-phase oxidation reaction mixture containing a monocarboxylic acid as a solvent and water, in the presence of a catalyst composition containing at least one heavy metal, which is effective for catalysing oxidation of the substituted aromatic hydrocarbon to an aromatic carboxylic acid, in a reaction section at high temperature and pressure, effective for keeping the liquid-phase oxidation reaction mixture in a liquid state and forming an aromatic carboxylic acid, and impurities containing by-products of oxidation of the initial aromatic hydrocarbon, which are dissolved or suspended in the liquid-phase oxidation reaction mixture, and a high-pressure vapour phase containing a solvent - monocarboxylic acid, water and small amounts of the initial aromatic hydrocarbon and by-products; transferring the high-pressure vapour phase from the reaction section into a separation section sprinkled by a liquid reflux containing water and capable of almost completely separating the solvent - monocarboxylic acid and water in the high-pressure vapour phase to form a liquid rich in solvent - monocarboxylic acid and depleted of water, high-pressure gas containing water vapour; transferring the high-pressure gas containing water vapour from the separation section without processing to remove organic impurities into a condensation section and condensation of the high-pressure gas to form a liquid condensate containing water and exhaust gas from the condensation section under pressure, containing non-condensed high-pressure gas components, transferred into the condensation section; removal from the condensation section of a liquid condensate containing water and suitable for use without further processing as at least one liquid containing water in a method of purifying aromatic carboxylic acids; and feeding the liquid condensate containing water removed from the condensation section during purification of aromatic carboxylic acids in which at least one step includes: (a) preparing a purification reaction solution containing an aromatic carboxylic acid and impurities which are dissolved or suspended in a liquid containing water; (b) bringing the purification reaction solution containing aromatic carboxylic acid and impurities in the liquid containing water, at high temperature and pressure, into contact with hydrogen in the presence of a hydrogenation catalyst to form a liquid purification reaction mixture; (c) separating the solid purified product containing carboxylic acid from the liquid purification reaction mixture containing aromatic carboxylic acid and impurities in the liquid containing water; and (d) using at least one liquid containing water to wash the obtained purified solid aromatic carboxylic acid separated from the liquid purification reaction mixture containing aromatic carboxylic acid, impurities and the liquid containing water; such that the liquid containing water on at least one step of the purification method contains a liquid condensate containing water and which needs processing to remove organic impurities.

EFFECT: invention also relates to apparatus for producing aromatic carboxylic acids.

44 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of drying aromatic carboxylic acid, involving drying of aromatic carboxylic acid precipitate using a fluidised bed drier, where the precipitate is fed into the drier at a rate of 50 kg/h or higher, and a drying gas at temperature 80-160°C is fed into the drier with reduced speed of 0.3-1 m/s, so that content of liquid in the precipitate is equal to or less than 14 wt %; as well as to an improved method of obtaining dry aromatic carboxylic acid, involving continuous drying of aromatic carboxylic acid precipitate using a fluidised bed drier to obtain ready aromatic carboxylic acid, where the precipitate is fed into the drier at a rate of 50 kg/h or higher, and drying gas at temperature 80-160°C is fed into the drier at reduced speed of 0.3-1 m/s so that content of liquid in the precipitate is equal to or less than 14 wt %. The aim of the invention is to develop a method of drying aromatic carboxylic acid and a method of drying aromatic carboxylic acid, each method solving problems associated with use of a fluidised bed drier, such as clogging by crystals or aromatic carboxylic acid crystals sticking in the drier, and low efficiency of the drier.

EFFECT: ensuring stable operation of a fluidised bed drier.

8 cl, 5 dwg, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of recovering energy during production of aromatic carboxylic acids via liquid phase oxidation of aromatic hydrocarbons wherein vapour containing reaction solvent and water forms in the top part of the reactor, and the method comprises the following steps: a) high efficiency separation of the vapour from the top part of the reactor to form at least a high-pressure gas stream containing water and organic impurities; b) recovering heat of the high-pressure gas stream via heat exchange with a heat sink, where a condensate forms, said condensate containing approximately 20-60 wt % water, present in the high-pressure gas stream, and high-pressure exhaust gas containing approximately 40-80 wt % water present in the high-pressure gas stream, remains uncondensed and temperature or pressure of the heat sink increases; and c) expansion of the high-pressure exhaust gas which is uncondensed at step (b), containing approximately 40-80 wt % water, present in the high-pressure gas stream, in order to recover energy of the high-pressure exhaust gas in form of work; and d) directing the heat sink, whose temperature and pressure increases at step (c), to another step of the method for heating or using outside the method. The invention also relates to a method of producing aromatic carboxylic acids with energy recovery and a device for recovering energy.

EFFECT: invention significantly lowers power consumption during production of aromatic carboxylic acids.

16 cl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to an improved continuous method of producing terephthalic acid, involving (a) feeding para-xylene into an oxidation reactor; (b) oxidation of at least a portion of said para-xylene in the liquid phase of a multi-phase reaction medium contained in said oxidation reactor until crude terephthalic acid is obtained, where said oxidation results in production of carbon dioxide, carbon monoxide and/or methyl acetate; and maintaining, during said oxidation, the molar ratio of obtained carbon oxides to said para-xylene in the range from 0.02:1 to 0.24:1. The invention also relates to a continuous method of producing terephthalic acid, involving (a) feeding para-xylene into an oxidation reactor; (b) oxidation of at least a portion of said para-xylene in the liquid phase of a multi-phase reaction medium, contained in said oxidation reactor, until crude terephthalic acid is obtained; and (c) maintaining, during said oxidation, molar ratio of persistence of said para-xylene in the range from 99.0 to 99.7%.

EFFECT: more efficient and cheaper liquid-phase oxidation of an oxidisable compound.

33 cl, 35 dwg, 7 tbl, 4 ex

FIELD: process engineering.

SUBSTANCE: invention relates to processing waste gases in production of aromatic dicarboxylic acid by liquid phase oxidation of aromatic dialkyl hydrocarbon, an initial substance, using acetic acid as a solvent, in the presence of metallic catalyst containing, as a promoter, cobalt, manganese and bromine at reactor temperature of 185 to 205°C and using oxygen-containing gas, that comprises the following stages: oxidation reaction waste gas is cooled down and separated. After condensation, waste gas condensing components are separated at high pressure. Obtained waste gas is subjected to wet cleaning at 40°C or lower temperature in high-pressure absorption columns by rinsing fluid into two stages to reduce concentration of components contained therein. Said waste gas at 12.0-16.0 kg/cm2(surplus) is forced through two-stage pressure turbines after heating of said gas fed to turbine first and second stage by steam at pressure of approx. 5 kg/cm2 (surplus) to 140°C - 150°C. Note here that two-stage turbines are used with second stage-to-first stage power ratio varying from 1 to 1.4 to obtain heat- and waste-gas-generated power in compliance with the formula below: (T2/T1)γ=(P2/P1)(γ-1), where γ = Cp/Cv = 1.4, T1, P1 are temperature and pressure at inlet side, T2, P2 are those at outlet side, γ is relation between specific heat capacity at constant pressure Cp to specific heat capacity at constant volume Cv.

EFFECT: efficient process and system.

6 cl, 9 tbl, 3 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to methods of producing aromatic carboxylic acids. The method involves the following, for example: bringing material which contains at least one substituted aromatic hydrocarbon, in which the substitutes can be oxidised to carboxyl groups, with oxygen gas in a liquid-phase oxidation reaction mixture which contains monocarboxylic acid as a solvent and water, in the presence of a catalyst composition meant for oxidising the substituted aromatic hydrocarbon to an aromatic carboxylic acid, containing at least one heavy metal, in a reaction section at high temperature and pressure sufficient for preservation of the liquid-phase oxidation reaction mixture and formation of an aromatic carboxylic acid and impurities containing by-products of the reaction, dissolved or suspended in the liquid-phase oxidation reaction mixture and a high-pressure vapour phase which contains a solvent - monocarboxylic acid, water and small quantities of the initial aromatic hydrocarbon and by-products of oxidation of the initial aromatic hydrocarbon and the solvent - monocarboxylic acid; moving the high-pressure vapour phase from the reaction section to a separation section in which the solvent - monocarboxylic acid, water and oxidation by-products are separated into at least one first liquid phase rich in the solvent - monocarboxylic acid and at least one second liquid phase rich in water, and at least one second high-pressure vapour phase stripped of the solvent - monocarboxylic acid, which contains water vapour, so that by-products of oxidation of the initial aromatic hydrocarbon are preferably in the first liquid phase and by-products of oxidation of the solvent - monocarboxylic acid are preferably in the second high-pressure vapour phase; and removal from the separation section in separate streams of the first liquid phase which is rich in the solvent - monocarboxylic acid, and the second liquid phase rich in water, which contains less than 5 wt % solvent - monocarboxylic acid and by-products of its oxidation, and the second high-pressure vapour phase which virtually contains less than 2 wt % by-products of oxidation of the initial aromatic hydrocarbon.

EFFECT: invention relates to an apparatus for producing aromatic carboxylic acids.

45 cl, 2 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to a method of processing polyethylene terephthalate wastes. The method involves ethanolysis of polyethylene terephthalate (PET), in which material containing PET reacts with ethanol. Ethylene glycol and an aromatic diethyl ester, such as diethyl isophthalate and/or diethyl terephthalate, are separated. PET or a terpolymer containing a terephthalate monomer and ethylene glycol monomers react with ethanol and ethanol, diethyl terephthalate, ethylene glycol and optionally diethyl isophthalate are separated. The separated diethyl components can undergo liquid-phase oxidation to obtain an aromatic carboxylic acid. Acetic acid can also be obtained via liquid-phase oxidation of the separated diethyl components. Aromatic carboxylic acid can be used to obtain polymers. The invention also describes apparatus for processing polyethylene terephthalate wastes. The apparatus includes a reactor, a distillation column operating at atmospheric pressure and a vacuum distillation column.

EFFECT: high efficiency of the method.

29 cl, 1 dwg, 8 tbl, 8 ex

Up!