JP2002226407A - Evaporation method for dicyclopentadiene, evaporating apparatus and thermal cracking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deposition of polymers and tar on the wall of a vaporizer and a cracking furnace and on the inner wall of piping in the production of cyclopentadiene, etc., by evaporating dicyclopentadiene and thermally cracking in vapor phase. SOLUTION: A dicyclopentadiene fraction containing inert hydrocarbon having a boiling point of >=300 deg.C is introduced as a descending stream into a vaporizer and evaporated. The inert hydrocarbon is removed by a demister attached to the discharging part of the evaporation equipment and the evaporated dicyclopentadiene fraction is introduced into a cracking furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for vaporizing a dicyclopentadiene fraction and a method for thermally decomposing dicyclopentadiene.

[0002]

2. Description of the Related Art Conventionally, a method of producing a crude dicyclopentadiene fraction from a pyrolysis (cracking) product such as naphtha or gas oil, and producing cyclopentadiene by thermal decomposition in a liquid or gas phase of the fraction. Has been put to practical use.

[0003] Many methods have been proposed as thermal decomposition methods for dicyclopentadiene. For example, a boiling point of 190
A method of thermally depolymerizing dicyclopentadiene in a liquid phase in a hydrocarbon fraction at ~ 250 ° C (GB Patent 612,
No. 893), a method of thermally depolymerizing dicyclopentadiene in a liquid phase in a hydrocarbon fraction having a boiling point of 250 to 350 ° C. (US Pat. No. 2,831,904, British Patent No. 769,813). And so on. Furthermore, a method has been proposed in which dicyclopentadiene is thermally decomposed in the gas phase in the presence of a diluent gas such as steam or nitrogen (US Pat. No. 2,582,920).

In any of the above-mentioned methods of thermally depolymerizing dicyclopentadiene in a hydrocarbon oil and the method of thermally decomposing in the gas phase, a polymer such as dicyclopentadiene is contained in a depolymerization or thermal decomposition apparatus. In addition, there is a problem that tar accumulates and blocks the piping of the reactor.

[0005] Therefore, several studies have been reported for preventing the blockage of the piping by the polymer and tar. For example, (1) the crude dicyclopentadiene fraction is vaporized by contacting it with superheated steam in a flash drum, and the polymer and tar are removed in the flash drum by a demister composed of a wire mesh; (2) a method in which superheated steam is mixed with dicyclopentadiene in a vaporization zone and superheated, and then a cyclopentadiene is introduced into a decomposition zone (JP-A-51-29145). No. 63151), (3) An apparatus is configured so that a mixture of a crude dicyclopentadiene fraction and water or / and steam forms a downward flow in a decomposition tube, and a polymer adheres to an inner wall of the decomposition tube. Thermal decomposition method of dicyclopentadiene to discharge the outside of the system (JP-A-5-78263).

[0006] However, in the above method (1), the polymer and tar are removed in the demister's droplet separation zone, but the treatment by a flash drum equipped with the demister is complicated. The use of superheated steam in the above method (2) is not economical because the equipment cost is high. The above method (3) has a problem that the removal of the polymer and the tar is not sufficient, and the flow of the vaporized dicyclopentadiene fraction causes the polymer to adhere to the pipe leading to the decomposition pipe (decomposition furnace). was there.

[0007]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a method for producing cyclopentadiene by pyrolyzing dicyclopentadiene in the gas phase to obtain a polymer or the like. An object of the present invention is to provide a vaporization method and a vaporization apparatus for a dicyclopentadiene fraction that can be stably operated for a long period of time without causing clogging of a pipe or the like due to tar. Further, another object of the present invention is to provide
It is an object of the present invention to provide a method for thermally decomposing dicyclopentadiene, which does not easily cause clogging of a pipe or the like caused by a polymer or tar and can be stably operated for a long period of time.

[0008]

The present inventors have conducted intensive studies on a method for producing cyclopentadiene by pyrolyzing a dicyclopentadiene fraction in the gas phase, and as a result, the polymer and tar are mainly produced in a vaporizer. It was found that the polymer and tar remained in the cracker furnace inlet pipe from the vaporizer outlet and clogged the pipe due to accumulation for a long time. Then, a dicyclopentadiene fraction preliminarily coexisting with a specific hydrocarbon is introduced (supplied) to the vaporizer, and a coexisting inert hydrocarbon is removed by a demister provided at a discharge section of the vaporizer. It has been found that the above object can be achieved by introducing the vaporized dicyclopentadiene fraction to a cracking furnace.

Thus, according to the first aspect of the present invention,
A dicyclopentadiene fraction in which an inert hydrocarbon having a boiling point of 300 ° C. or higher coexists is introduced into a vaporizer by a downward flow to be vaporized, and the inert hydrocarbon is passed through a demister provided at a gas discharge portion of the vaporizer. And a method for vaporizing dicyclopentadiene.

According to a second aspect of the present invention, the vaporizer is configured such that the dicyclopentadiene fraction coexisting with an inert hydrocarbon having a boiling point of 300 ° C. or higher forms a downward flow in the vaporizer. A demister for removing the inert hydrocarbon is disposed at a gas discharge portion of the vaporizer, and a lower end of the gas discharge portion is provided so that a discharged gas passes through a mist separation zone of the demister. And a vaporizer for dicyclopentadiene, wherein the vaporizer is open in the demister.

Further, according to a third invention of the present invention, the vaporized dicyclopentadiene fraction obtained by the method of the first invention is introduced into a cracking furnace to be thermally decomposed. A method for pyrolyzing dicyclopentadiene is provided.

[0012]

DETAILED DESCRIPTION OF THE INVENTION In the vaporization method and vaporizer present invention, crude dicyclopentadiene used as a raw material, the C ₅ fraction by-produced during the pyrolysis of naphtha treated dimerization, the unreacted material And by-products are removed to increase the content of dicyclopentadiene. Also,
Also it is obtained by treating the dimerization and the remaining spent -C ₅ fractions extracted isoprene from the C ₅ fraction.

The crude dicyclopentadiene is fed to a vaporizer after the concentration of dicyclopentadiene is usually increased to 60% by weight or more, preferably 70% by weight or more by distillation.
The residual components of the crude dicyclopentadiene obtained by such distillation are, for example, vinyl norbornene, isopropenyl norbornene, propenyl norbornene, tricyclopentadiene and the like.

In the method for vaporizing dicyclopentadiene according to the present invention, the crude dicyclopentadiene is mixed with an inert hydrocarbon having a boiling point of 300 ° C. or higher, that is, in the presence of an inert hydrocarbon having a boiling point of 300 ° C. or higher. It is essential to supply to

The inert hydrocarbon having a boiling point of 300 ° C. or higher is not particularly limited. Examples thereof include biphenyls substituted with an alkyl group such as diethyl biphenyl and triethyl biphenyl; ortho-triphenyl, meta-triphenyl, para-triphenyl Triphenyls obtained by thermal condensation of benzene; hydrogenated triphenyls obtained by nuclear hydrogenation of the above triphenyls; alkyls such as 1,2,3-trimethylnaphthalene and 1,2,5-trimethylnaphthalene Substituted naphthalenes; triphenylmethane, 1,
Alkanes substituted by a phenyl group such as 1,2-triphenylethane and 1,1,1-triphenylethane; benzenes having a substituent such as dibenzylbenzene and dibenzyltoluene;

These hydrocarbons may be used alone or in combination of two or more. The amount used (weight basis) is usually 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the crude dicyclopentadiene.
% By weight. If the amount is too small, the production of the polymer becomes remarkable. If the amount is too large, it is not economical because an excessive heat supply to the vaporizer is required.

The above-mentioned inert hydrocarbon having a boiling point of 300 ° C. or higher is generally known as an “organic heat carrier” in the field of the chemical industry, and a commercially available product can be obtained and used. Examples of such commercially available products include “Therms 700”, “Therms 800”, “Therms 900”, “Purified Triphenyl Mixture” manufactured by Nippon Steel Chemical Co., Ltd., and “Neo SK” manufactured by Soken Chemical Co., Ltd.
-L400 "and" Neo SK-OIL1400 ".

A mixture of the crude dicyclopentadiene and the inert hydrocarbon having a boiling point of 300 ° C. or higher may further contain a diluent, if desired. As the diluent, those which are inert, have high thermal stability, and have a lower boiling point than dicyclopentadiene are preferable. Specific examples of such a diluent include n-propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, n-heptane, and n-propane.
-Saturated aliphatic hydrocarbons such as octane and n-nonane; saturated alicyclic hydrocarbons such as cyclopentane and cyclohexane; unsaturated aliphatic hydrocarbons such as pentene and hexene;
Examples thereof include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene. The amount of diluent added
It is usually 2 to 50% by weight, preferably 5 to 30% by weight, based on the crude dicyclopentadiene.

The vaporizer may be either a packed tower or a spray tower. A mixture of crude dicyclopentadiene and an inert hydrocarbon having a boiling point of 300 ° C. or higher is introduced into a vaporizer in a downward flow, and then heated in the vaporizer to 140 to 240 ° C. From the demister (mist separator)
Guided inside. Inert hydrocarbons having a boiling point of 300 ° C. or higher
Although it does not evaporate in the vaporizer, it passes through the vaporizer in the form of a mist due to the completely vaporized gas flow of dicyclopentadiene, is discharged with the gas into the demister, and is removed there. .

As shown in FIG. 1, the gas discharge part of the vaporizer 1 is constituted by a discharge pipe 2 directed downward. The lower end of the discharge pipe 2 opens into the demister 3. The inert hydrocarbon having a boiling point of 300 ° C or higher coexisted in the dicyclopentadiene fraction passes through the vaporizer in a downward flow together with the vaporized dicyclopentadiene, so that the polymer and tar adhere to the inner wall surface of the vaporizer. I will not. The polymer and tar are washed off into the demister 3 by the inert hydrocarbon.

The capacity of the demister 3 is not particularly limited, and may be selected to a size corresponding to the capacity of the vaporizer 1. The shape is not particularly limited, and may be, for example, a cylindrical shape. Although the material is not limited, for example, S
Stainless steel with good corrosion resistance, such as US304 and SUS316, is preferable.

A mist separator 4 made of wire mesh or the like is provided in the upper part of the demister 3, and the discharge pipe 2 penetrates the mist separator 4 and opens downward. The inert hydrocarbons discharged in the form of a mist from the discharge pipe are condensed and removed when passing through the mist separation zone 4, but the dicyclopentadiene gas passes through the mist separation zone 4 as it is. The mist separation zone 4 also prevents the polymer and tar from being led to the next thermal decomposition step.

The size of the wire mesh is not particularly limited, but usually, about 80 to 100 mesh is preferably used. The material is not particularly limited, but preferably does not cause any trouble such as corrosion. For example, SUS3
04, stainless steel such as SUS316 is used.
The mist separator 4 may be a layer filled with a metal or porcelain lahishling, in addition to a wire mesh.

The inert hydrocarbons, polymer and tar removed by the mist separation zone 4 are discharged from the demister wall through a discharge pipe 6. The dicyclopentadiene fraction that has been vaporized and passed through the mist separation zone is then led to the pyrolysis furnace 5. The pyrolysis furnace 6 has a temperature sufficient to pyrolyze dicyclopentadiene into cyclopentadiene,
Usually, it is kept at about 250 to 450 ° C. The cracked gas derived from the pyrolysis furnace is guided to a cyclopentadiene separation step according to a conventional method. The undecomposed dicyclopentadiene recovered here can be reused in the vaporization step of the present invention.

[0025]

EXAMPLES The present invention will be described below in detail with reference to examples, but the scope of the present invention is not limited by these examples.

Example 1 Crude dicyclopentadiene was diluted with cyclopentene,
Further, Neo-SK OIL L is used as an inert hydrocarbon.
-400 (manufactured by Soken Chemical; standard boiling point: 460 ° C)
A mixture having the composition shown in Table 1 (area% by Guss chromatography analysis) was prepared. About 115
° C and fed to the vaporizer at a rate of 9 g / min. The vaporizer was constituted by vertically inserting a SUS304 stainless steel tube having an inner diameter of 2 mm into a SUS304 stainless steel tube having an inner diameter of 3 mm and a length of 1,000 mm so that the raw material mixture could flow through the gap. The inside of the vaporizer was electrically heated and maintained at 170 ° C. Outer diameter about 8 as demister
0 mm, depth of about 400 mm cylindrical container (SUS304
Wire mesh provided inside the demister (SUS304, mesh size: about 90 mesh)
The lower end (gas discharge part) of the vaporizer stainless steel pipe having the layer penetrated was opened at a position 15 cm from the bottom of the demister. The demister was also electrically heated and kept at 250 ° C.
The mixture introduced into the demister was passed through a wire mesh and led to a pyrolysis furnace. The pyrolysis furnace was maintained at 340 ° C. by electric heating. From the bottom of the demister, a mixture of polymer, tar and inert hydrocarbon was withdrawn at any time. The composition of the gas derived from the pyrolysis furnace was as shown in Table 1. After the operation was continued for 400 hours, substantially no deposits such as polymers were found on the piping from the vaporizer, the demister to the pyrolysis furnace, and the inner wall of the pyrolysis furnace.

[0027]

[Table 1]

Comparative Example 1

The dicyclopentadiene vaporization and decomposition apparatus was operated in the same manner as in Example 1 except that the inert hydrocarbon used in Example 1 was not added.
After a lapse of time, the polymer was contaminated on the lower end of the vaporizer and on the inner surface of the pipe from the demister to the pyrolysis furnace.

[0030]

According to the method for vaporizing dicyclopentadiene of the present invention, clogging of pipes or the like due to a polymer or tar hardly occurs, and stable continuous operation can be performed for a long period of time. .

[Brief description of the drawings]

FIG. 1 is a view showing a vaporization step and a pyrolysis step of dicyclopentadiene according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vaporizer 2 vaporizer gas discharge section 3 demister 4 mist separation zone 5 pyrolysis furnace 6 discharge pipe for inert hydrocarbon, polymer and tar

Claims (3)

[Claims] 1. A dicyclopentadiene fraction in which an inert hydrocarbon having a boiling point of 300 ° C. or higher coexists is introduced into a vaporizer by a downward flow to be vaporized, and is vaporized by a demister provided at a gas discharge portion of the vaporizer. A method for vaporizing dicyclopentadiene, comprising removing the inert hydrocarbon. 2. A vaporizer is configured such that a dicyclopentadiene fraction coexisting with an inert hydrocarbon having a boiling point of 300 ° C. or higher forms a downward flow in the vaporizer, and a gas discharge portion of the vaporizer is provided. A demister for removing the inert hydrocarbon is provided, and the lower end of the gas discharge portion is opened in the demister so that the discharged gas passes through the mist separation zone of the demister. Characteristic vaporizer for dicyclopentadiene. 3. A method for thermally decomposing dicyclopentadiene, comprising introducing a vaporized dicyclopentadiene fraction obtained by the vaporization method according to claim 1 into a cracking furnace for thermal decomposition.