JPH055831U - Reactor for aromatic carboxylic acid, crystallizer and suspension washer - Google Patents

Abstract

(57) [Summary] (Modified) [Constitution] Reactor for producing an aromatic carboxylic acid by reacting an alkyl aromatic hydrocarbon and / or an oxidation product thereof with molecular oxygen in a liquid phase. 1. A crystallizer and a suspension washer, which are located near the top of the reactor and the like, and a liquid reservoir 3 attached to a stirring rotary shaft 2 and a solvent dispersion pipe 4 located at an outer peripheral portion of the liquid reservoir, and It is characterized in that it has a solvent dispersion unit comprising a solvent supply pipe 5 located above the liquid reservoir. [Effect] The inner wall of a reactor or the like can be uniformly and efficiently washed with a very small amount of solvent.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to a reactor, a crystallizer and a suspender used for producing an aromatic carboxylic acid. To do.

[0002]

[Prior art]

  Aromatic carboxylic acids generally contain alkyl aromatic hydrocarbons in the liquid phase in the presence of a catalyst. A method of reacting with molecular oxygen under the present circumstances is adopted. In the reaction, an aromatic catalyst is usually used. Rubic acid forms in the liquid phase as a poorly soluble crystalline material.   For example, terephthalic acid is usually prepared by converting para-xylene into acetic acid solvent, heavy metal and bromine. The method of production by liquid phase oxidation with molecular oxygen in the presence of a compound is widely practiced. ing. In this method, the terephthalic acid produced has a low solubility in a solvent and is Many precipitates as crystals. Then, it was carried along with the solvent to the gas phase section above the reactor. Crystals of terephthalic acid adhered to the inner wall of the reactor and solidified, making recovery from the reactor difficult. Become.

[0003]   Therefore, conventionally, part of the condensate of evaporated acetic acid contained in the exhaust gas of the reactor was It is shown that the inner wall of the reactor is washed by returning it to the upper part (Japanese Patent Publication No. 57-4465). 4). In addition, the raw material para-xylene and the solvent acetic acid are continuously added to the gas phase region above the reactor. It is known to be supplied in the form of mist or droplets (Japanese Examined Patent Publication No. 45-30812). ).   In addition, a flat plate-shaped obstacle is installed in the middle of the solvent flow to supply the solvent to the reactor. It is also possible to spread it over many parts of the inner wall of the.

[0004]   On the other hand, it is possible to use a non-adhesive material for the reactor, but When handling highly corrosive aromatic carboxylic acids under high pressure, the materials are titanium and zirco. It is limited to some metallic materials such as metal.   Regarding the above points, the crystallizer in the post-treatment step of the carboxylic acid obtained in the reactor, This was a common problem that could be encountered in a water washer.

[0005]

[Problems to be solved by the device]

  However, if the condensate is circulated, in reality, the entire amount of condensate is However, it was difficult to wash the inner wall of the reactor uniformly and sufficiently even after returning to the above condition. Also mist Or, in order to effectively wash with a solvent in the form of droplets, a high-pressure compressor for solvent supply is used. Had to control the ssser.

[0006]

[Means for Solving the Problems]

  The present inventor has conducted various investigations in view of the above circumstances, and as a result, If a solvent dispersion unit is installed, the inner wall of the reactor top can be efficiently used with a very small amount of solvent. They have found that they can be washed uniformly, and have reached the present invention.

[0007]   That is, the technical idea of the present invention is used in the production of aromatic carvone. It is embodied in three modes: a reactor, a crystallizer, and a suspender. What is the reactor of the first aspect? , Alkylaromatic hydrocarbons and / or their oxidation products in the liquid phase A reactor for producing an aromatic carboxylic acid by reacting with an element, said reactor A liquid reservoir located near the top of the tank and attached to the stirring rotary shaft. A solvent dispersion pipe located at the top and a solvent supply pipe located above the liquid reservoir. A reactor for an aromatic carboxylic acid, which has a unit for dispersing a medium. .   Hereinafter, the present invention will be described in detail focusing on the above-mentioned reactor.

[0008]   Aromatic carboxylic acids covered by the present invention include terephthalic acid and isophthalic acid. , Phthalic acid, benzoic acid, paratoluic acid, naphthalenedicarboxylic acid, etc. are exemplified. , The corresponding alkyl aromatic hydrocarbons and / or their oxidation products as raw materials Then, it is produced by reacting with molecular oxygen in the liquid phase.

[0009]   For example, with respect to terephthalic acid, paraxylene is added to cobalt in acetic acid solvent. In the presence of catalysts containing heavy metals such as manganese and manganese, and bromine compounds, the reaction with molecular oxygen The method of adapting is adopted. In addition, after taking out the reaction solution from the reactor once, Furthermore, para-toluic acid, which is an intermediate of the oxidation reaction from para-xylene to terephthalic acid, , 4-carboxybenzaldehyde and other oxidation products, and residual para-xylene The present invention is also applicable to the case of additional oxidation reaction.

[0010]   The ratio of para-xylene to the solvent supplied to the reactor is usually 2 to para-xylene. 6 times by weight, and when the amount of the solvent is too small, the reactor is well stirred. Absent.   Hereinafter, the reactor of the present invention will be described with reference to the drawings. FIG. 1 shows an example of the present invention. 2 is a schematic view of a longitudinal section of a reactor for aromatic carboxylic acids, FIG. 2 being A--A in FIG. 'It is a cross section. 1 and 2, 1 is a reactor, 2 is a stirring rotary shaft, and 3 is a liquid. The reservoir 4 is a solvent dispersion pipe, 5 is a solvent supply pipe, 6 is a liquid surface, and 7 is a stirring blade.

[0011]   The unit for dispersing a solvent, which is a feature of the reactor of the present invention, is the top of the reactor. Liquid reservoir 3 located in the vicinity and attached to the stirring rotary shaft 2, and an outer peripheral portion of the liquid reservoir 3. The solvent dispersion pipe 4 located at the upper part of the liquid reservoir, and the solvent supply pipe 5 located above the liquid reservoir. Consists of

[0012]   The solvent used for dispersion may be newly supplied from the outside or a part of the reaction solution. Is continuously vaporized, and most of the liquid discharged from the reactor and condensed is discharged from the reactor. It may be circulated to the bottom and a part of the condensate may be used as a dispersion solvent. Dispersion solvent The supply amount is the same when the amount of the reaction mixture in the reactor is 100 volume in the steady state. A very small amount of solvent such as 0.2 to 10 volume / hr, preferably 1 to 4 volume / hr. The entire inner wall of the reactor can be sufficiently washed with.

[0013]   The liquid reservoir 3 is located near the top of the reactor and is installed on the stirring rotary shaft 2. reaction The shape of the reactor is not particularly limited, but in the case of a cylindrical reactor as shown in FIG. From the viewpoint of cleaning effect, it is preferable that the position is 10 to 30% of the total length of the reactor from the top. Set up. The shape of the cross section of the liquid reservoir 3 is circular, oval, equilateral triangle, square or polygon. Any shape is possible, but it is preferably circular. The volume of the liquid reservoir 3 is It is usually 0.01 to 1%, preferably 0.05 to 0.5% of the total volume of the reactor.

[0014]   Next, the solvent dispersion pipe 4 is installed on the outer peripheral portion of the liquid reservoir 3. The number of solvent dispersion tubes There is no particular limitation, and 1 to 4 are usually installed. Also, the mounting angle of the dispersion pipe is washed In consideration of the effect, it can be installed diagonally upward or downward, but facing the liquid surface It can also be installed in parallel (right angle to the side wall of the reactor). The diameter of the dispersion tube is Usually 0.001 to 0.02 times the diameter of the cross section of the reactor, preferably 0.0 It is from 02 to 0.01 times. In addition, the tip of the dispersion tube is usually 50 to 50 mm of the radius of the reactor. 90%, preferably 60-75%.   Furthermore, the shape of the vertical section of the dispersion pipe is a divergent type, a squeezed type, or a straight type. Any of these types may be used, but preferably the solvent outflow linear velocity is high and the cleaning effect is high. It is a dead-end type.

[0015]   Finally, regarding the solvent supply pipe 5, the solvent can be supplied to the liquid reservoir 3. It suffices to install it on the upper part of the liquid reservoir 3, and there is no limitation on the shape or the like.   Since the above-mentioned solvent dispersion unit is installed on the stirring rotary shaft 2, during the reaction, In this case, it may be used with stirring and rotating the stirring blade 7, and a new rotating device is installed. You don't have to.

[0016]   The features of the reactor of the present invention described above are that the carboxylic acid obtained in the reactor is recovered and Crystallizer for precipitation, and for suspending the obtained carboxylic acid crystals with a solvent The same can be applied to the suspension washing machine.   That is, the second aspect of the present invention relates to an alkyl aromatic hydrocarbon and / or its oxidation. Recover the aromatic carboxylic acid obtained by reacting the product with molecular oxygen in the liquid phase A crystallizer for use in agitation, which is located near the top of the crystallizer and attached to a stirring rotary shaft. A liquid dispersion pipe located at the outer peripheral portion of the liquid reservoir and the upper part of the liquid reservoir A solvent supply pipe located in the A crystallizer for aromatic carboxylic acids.

[0017]   Further, a third aspect of the present invention relates to an alkyl aromatic hydrocarbon and / or its oxidation. Aromatic carboxylic acid suspension washers obtained by reacting the product with molecular oxygen in the liquid phase Is located near the top of the suspension washer and is attached to the stirring rotary shaft. Solvent dispersion pipe located in the outer peripheral portion of the liquid reservoir and solvent located in the upper portion of the liquid reservoir Aromatic carvone characterized by having a solvent dispersion unit consisting of a supply pipe Located in the acid suspension washer.   The above crystallizer and suspension washer may be used with the same configuration as the above-mentioned reactor.

[0018]

[Effect of device]

  By using the reactor, crystallizer and suspension washer of the present invention, it is possible to react with a very small amount of solvent. The inner wall of the reactor can be cleaned uniformly and efficiently, and the reaction of aromatic carboxylic acid crystals It is possible to prevent the adhesion and solidification to the reactor or the like. Also, in the case of a reactor, especially Since the foam layer on the reaction interface can be made small, the vapor and heat in the reactor can be dissipated. It also has the effect of smoothing the production of aromatic carboxylic acids such as terephthalic acid for a long time. It can be performed stably for a while.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a reactor for producing an aromatic carboxylic acid showing an example of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ in FIG.

[Explanation of symbols]

(1): Reactor (2): Agitating rotary shaft (3): Liquid reservoir (4): Solvent dispersion tube (5): Solvent supply pipe (6): Liquid level (7): Stirrer

Claims (3)

[Scope of utility model registration request] 1. A reactor for producing an aromatic carboxylic acid by reacting an alkylaromatic hydrocarbon and / or an oxidation product thereof with molecular oxygen in a liquid phase,
A solvent dispersion unit including a liquid reservoir located near the top of the reactor and attached to a stirring rotary shaft, a solvent dispersion pipe located at an outer peripheral portion of the liquid reservoir, and a solvent supply pipe located above the liquid reservoir. A reactor for an aromatic carboxylic acid, which comprises: 2. A crystallizer for recovering an aromatic carboxylic acid obtained by reacting an alkylaromatic hydrocarbon and / or an oxidation product thereof with molecular oxygen in a liquid phase, A liquid reservoir located in the vicinity of the top of the crystallizer and attached to a stirring rotary shaft, a solvent dispersion pipe located at an outer peripheral portion of the liquid reservoir, and a solvent supply pipe located above the liquid reservoir;
A crystallizer for an aromatic carboxylic acid, comprising a solvent dispersion unit comprising 3. A suspension washer of an aromatic carboxylic acid obtained by reacting an alkyl aromatic hydrocarbon and / or an oxidation product thereof with molecular oxygen in a liquid phase, the suspension washer. And a solvent dispersion pipe which is located near the top of the liquid reservoir and is attached to the stirring rotary shaft and is located in the outer peripheral portion of the liquid reservoir and a solvent supply pipe located above the liquid reservoir. A suspension washing device for aromatic carboxylic acids, characterized in that