JP6766528B2 - Hydrogenated coal tar pitch manufacturing equipment - Google Patents

Description

The present invention relates to an apparatus for producing a hydrogenated coal tar pitch by hydrogenating a coal tar pitch. More specifically, the present invention relates to an apparatus for producing hydrogenated coal tar pitch by desulfurizing and denitrifying coal tar pitch by hydrogenation treatment.

Coal tar, which is produced as a by-product during carbonization of coal, is mostly composed of condensed polycyclic aromatic compounds, and has long been used as a raw material for various carbon products. The composition ratio of the coal tar-based product group is obtained from the product group such as creosote oil and naphthalene obtained from the distillate oil component in about 30%, and the coal tar pitch of the heavy component in which the remaining 70% is the non-distillate component. It is a product group that can be used.
Of these, needle coke produced from coal tar pitch occupies an important position as a particularly high value-added product, and is mainly used as an aggregate for graphite electrodes for electric steelmaking. In the process of manufacturing a graphite electrode, first, needle coke grains and a binder pitch are mixed in a predetermined ratio, heat-kneaded, and then extruded to manufacture a raw electrode. Graphite electrode products can be obtained by firing this raw electrode, graphitizing it, and then processing it.

Since this graphite electrode is used under harsh high temperature conditions, extremely high thermal shock resistance is required. Needle coke with a small coefficient of thermal expansion (CTE) is required to produce graphite electrodes with high thermal shock resistance. Needle coke made from coal tar pitch (hereinafter, may be referred to as pitch-based needle coke) has the smallest coefficient of thermal expansion among all cokes, and is therefore the most preferable as a raw material for graphite electrodes. However, while pitch-based needle cox provides high-quality graphite electrodes, it tends to cause an irreversible expansion phenomenon called puffing in the process of graphitizing the electrodes, and cracks occur in the product when it is rapidly graphitized. Therefore, it has the disadvantage that the yield is significantly reduced.

Therefore, in the production of graphite electrodes, it is necessary to raise the temperature for graphitization over a long period of time, and the productivity is extremely low.
This puffing phenomenon is caused by abnormal expansion due to rapid volatilization of nitrogen from heterocompounds contained in pitch-based needle coke and sulfur in the region of 2500 to 2800 ° C, mainly in the region of 1500 to 2000 ° C in the graphitization process. It is believed that.

In order to eliminate such a puffing phenomenon, some methods have been adopted in the manufacturing process of graphite electrodes. For example, by adding a small amount of iron oxide in the process of mixing pitch-based needle coke and binder pitch, which is a binder, a method of forming a stable compound of sulfur and iron in coke during graphitization to suppress puffing. , There is a method of adjusting the bulk density of graphite electrodes in the molding step to facilitate the volatilization of gas generated during graphitization. However, although the former method has a certain effect in reducing the expansion derived from sulfur, the effect of reducing the expansion derived from nitrogen is not seen, and the latter method mechanically reduces the bulk density of the graphite electrode. There was a problem that it led to a decrease in strength.

In addition to the above, various methods for suppressing puffing during the production of graphite electrodes using needle coke have been proposed.
Patent Documents 1 and 2 propose a method of reducing puffing by heat-treating pitch coke at 1500 ° C. or higher to denitrify it. Further, Patent Document 3 discloses a method in which raw coke is pretreated in advance by an oxidation treatment or the like and then heat-treated at a normal baking temperature. These methods have a problem that the former method consumes a large amount of energy due to high-temperature heating, and the latter method complicates the process as compared with the conventional method.

Regarding pitch-based needle coke, Patent Document 4 discloses a method for producing needle coke in which coal tar pitch from which quinoline insoluble matter has been substantially removed and petroleum-based heavy oil are mixed and the mixture is carbonized. However, this method does not have a sufficient effect of suppressing puffing.
In Patent Document 5, raw coke is produced from a raw material obtained by mixing coal-based heavy oil and petroleum-based heavy oil so that both nitrogen content and sulfur content are adjusted to be equal to or less than a specific value, and this raw coke is used. It is said that needle coke with low puffing can be obtained by baking in two stages. However, the effect of this method is limited, and there is a concern that the coke yield may decrease due to two-stage calcination and the bulk density of the graphite electrode may decrease due to the porosity of coke.

Patent Document 6 describes that when a hydrogenated coal tar-based raw material is used, needle coke with reduced puffing can be obtained. This is a process that is expected to improve the quality of needle coke by structural changes of condensed polycyclic aromatic compounds, in addition to the direct effect of removing sulfur and nitrogen by hydrorefining coal tar-based raw materials. However, the hydrogenation treatment disclosed here applies the reaction conditions of the hydrodesulfurization process using atmospheric residual oil as a raw material oil in the petroleum refining industry, so that the production cost is high and the coke yield is low. The problem that hydrogenation reduces the amount of aromatic compounds that are characteristic of pitch-based heavy oils still remains.

Under the above circumstances, the present inventors have clarified suitable hydrogenation conditions and the like when hydrogenating coal tar pitch to produce hydrogenated coal tar pitch (Patent Documents 7 and 8). Furthermore, it was also found that the needle coke thus obtained had a low CTE and suppressed puffing.

Japanese Unexamined Patent Publication No. 60-33208 Japanese Unexamined Patent Publication No. 60-208392 Japanese Unexamined Patent Publication No. 63-135486 Japanese Patent Application Laid-Open No. 3-25090 JP-A-5-163491 JP-A-59-12258 JP 2015-166443 JP 2015-166444

In Patent Documents 7 and 8, it has been found that by optimizing the hydrogenation conditions, needle coke having a low CTE and suppressed puffing can be obtained. However, according to the studies by the present inventors, a large amount of energy is required to hydrogenate the coal tar pitch by the methods described in these documents, and the amount of hydrogen required for hydrogenation is also large. Became clear. Furthermore, it has been found that it is difficult to control the temperature in the hydrogenation reaction, which is an exothermic reaction and is a high temperature reaction.

The present invention has been made in view of the above circumstances, and it is possible to efficiently produce a hydrogenated coal tar pitch capable of obtaining a pitch-based needle coke having a small coefficient of thermal expansion and sufficiently suppressed puffing. The purpose is to provide various devices.
Another object of the present invention is to provide a manufacturing apparatus capable of reducing hydrogen consumption and performing an efficient hydrogenation reaction when producing hydrogenated coal tar pitch from coal tar pitch. ..
Another object of the present invention is to provide a manufacturing apparatus capable of performing a hydrogenation reaction by controlling the temperature when producing hydrogenated coal tar pitch from coal tar pitch.

As a result of diligent studies on the above problems, the present inventors separated the light oil from the hydrogenated coal tar pitch in an apparatus for producing the hydrogenated coal tar pitch by hydrogenating the raw material coal tar pitch, and hydrogenated the separated light oil. The present invention has been found to be able to solve the above-mentioned problems by providing an apparatus provided with a recycling circuit for supplying the chemical processing apparatus.

That is, the gist of the present invention is the following [1] to [11].
[1] A hydrogenation treatment device for hydrogenating the raw coal tar pitch, a separation device for separating light oil from the hydrogenated coal tar pitch discharged from the hydrogenation treatment device, and a light oil separated by the separation device. A hydrogenated coal tar pitch manufacturing device equipped with a recycling circuit that supplies the hydrogenated coal tar pitch.

[2] The hydrogenated coal tar pitch manufacturing apparatus according to [1], wherein the recycling circuit is a circuit for supplying light oil to the hydrogenation treatment apparatus together with the raw material coal tar pitch.
[3] Described in [1] or [2], wherein the hydrogenation treatment apparatus is provided with a temperature sensor and has a function of controlling the amount of light oil supplied to the hydrogenation treatment apparatus according to the temperature information from the temperature sensor. Hydrogenated coal tar pitch manufacturing equipment.
[4] The hydrogenated coal tar pitch manufacturing apparatus according to [1] or [2], wherein the recycling circuit is a circuit for supplying light oil to a plurality of locations of the hydrogenation treatment apparatus.

[5] The hydrogenation treatment apparatus is provided with a plurality of temperature sensors, and has a function of controlling the supply amount of a plurality of circuits for supplying light oil to the hydrogenation treatment apparatus according to the temperature information from the temperature sensors [5]. 4] The hydrogenated coal tar pitch manufacturing apparatus.

[6] The apparatus for producing a hydrogenated coal tar pitch according to any one of [1] to [5], wherein the recycling circuit is provided with a cooling device for cooling light oil.
[7] The hydrogenated coal tar pitch manufacturing apparatus according to [6], wherein the cooling device is a heat exchanger.
[8] The apparatus for producing a hydrogenated coal tar pitch according to any one of [1] to [7], wherein the hydrogenation treatment apparatus is a continuous fixed bed reactor.
[9] The apparatus for producing a hydrogenated coal tar pitch according to any one of [1] to [8], wherein the separator is a distillation column or a gas-liquid separator.
[10] The hydrogenation treatment apparatus has a line for supplying raw material coal tar pitch and hydrogen, and the line for supplying coal tar pitch and the line for supplying hydrogen are previously merged [1]. ] To [9]. The hydrogenated coal tar pitch manufacturing apparatus.
[11] The hydrogenation treatment apparatus has a raw material coal tar pitch supply port and a hydrogen supply port, and at least one hydrogen supply port is provided on the downstream side of the raw material coal tar pitch supply port. The apparatus for producing a hydrogenated coal tar pitch according to any one of [1] to [9].

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an apparatus capable of efficiently producing a hydrogenated coal tar pitch suitable as a raw material for pitch-based needle coke having a small coefficient of thermal expansion and sufficiently suppressed puffing.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a manufacturing apparatus capable of reducing hydrogen consumption and performing an efficient hydrogenation reaction when producing hydrogenated coal tar pitch from coal tar pitch.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a manufacturing apparatus capable of performing a hydrogenation reaction by controlling the temperature when producing hydrogenated coal tar pitch from coal tar pitch.

It is a schematic diagram which shows an example of the manufacturing apparatus of the hydrogenated coal tar pitch of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus of the hydrogenated coal tar pitch of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus of the hydrogenated coal tar pitch of this invention. It is a schematic diagram which shows an example of the manufacturing apparatus of the hydrogenated coal tar pitch of this invention.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and carried out without departing from the gist of the present invention. In the following, "% by mass" and "% by weight", and "parts by mass" and "parts by weight" are synonymous with each other.
In the present invention, "pitch-based" and "coal-based" are treated as synonymous terms.

The "sulfur content" as used in the present invention means a value measured according to JIS M8813 for coal tar pitch, JIS K2541 for petroleum oil, and JIS M8813 for coke.
The "nitrogen content" as used in the present invention means a value measured according to JIS M8819 for coal tar pitch, JIS K2609 for petroleum oil, and JIS M8819 for coke.
The specific gravity of coal tar pitch, quinoline insoluble content, toluene insoluble content, and fraction below 360 ° C. all mean values measured according to JIS K2425, and viscosity means values measured with a B-type rotational viscometer. ..

The present invention includes a hydrogenation treatment device for hydrogenating the raw coal tar pitch and a separation device for separating light oil from the hydrogenated coal tar pitch discharged from the hydrogenation treatment device, and is separated by the separation device. It is a device equipped with a circuit that supplies light oil to the hydrogenation treatment device. Hereinafter, the present invention will be described in detail with reference to the drawings.

[1. Raw material coal tar pitch]
In the present invention, the raw material coal tar pitch supplied to the hydrogenation treatment apparatus is not limited, but it is preferably one having the following characteristics.
The manufacturing method (pre-adjustment method) and manufacturing equipment of the raw material coal tar pitch are not limited, but in general, the quinoline insoluble matter is substantially removed from the coal tar-based heavy oil in advance, or the coal tar-based heavy oil is used. It can be obtained by substantially removing the quinoline insoluble matter after mixing with petroleum-based heavy oil.

A known method can be applied as a means for removing the insoluble quinoline, and examples thereof include a method of treating a coal tar-based heavy oil with an aromatic oil or an aliphatic oil, and a mixed solvent thereof. It is also preferable to treat with. As the aliphatic oil, an alicyclic compound such as cyclohexane or cyclopentane, a compound having a carbonyl group such as acetone or ether, a light oil or the like can be used. As the aromatic oil, tar-based cleaning oil, anthracene oil and the like can be used. The pitch and solvent are mixed under appropriate conditions, heated and then allowed to stand as necessary, and then the mixture is distilled to distill off low boiling point components to obtain a raw material coal tar pitch containing almost no quinoline insoluble matter. Can be done.

It is preferable that the raw material coal tar pitch has a good growth state of a liquid crystal called mesoface in the process of coking. Mesoface is an intermediate product formed by thermal decomposition and polycondensation caused by heat treatment of raw material oil, and a series of aromatic rings is developed along the same plane. It is thought that the coefficient of thermal expansion of needle coke can be reduced if this mesoface grows large and is oriented in the uniaxial direction. Therefore, it is preferable to generate a mesoface with highly developed crystals.

The quinoline insoluble content of the raw material coal tar pitch is preferably 0.2% by weight or less. When the quinoline insoluble content of the raw material coal tar pitch exceeds 0.2% by weight, the growth of the mesoface in the coking process is suppressed, so that the coefficient of thermal expansion of the needle coke tends to increase. The lower limit of the quinoline insoluble content of the raw material coal tar pitch is not limited, but is usually 0.0001% by weight or more. If the quinoline insoluble content is less than 0.0001% by weight, it is difficult to obtain it, and in such a raw material coal tar pitch, the content ratio of light oil is high, and the coke yield tends to be low. Furthermore, the effect of performing the hydrogenation treatment using the apparatus of the present invention tends to be difficult to be exhibited. Further, the quinoline insoluble content is more preferably 0.001 to 0.1% by weight for the same reason as described above.

The sulfur content of the raw material coal tar pitch is preferably 0.4 to 0.8% by weight. If the sulfur content of the raw material coal tar pitch exceeds 0.8% by weight, the sulfur content in the pitch after hydrogenation using the apparatus of the present invention will not be sufficiently reduced, so that puffing of needle coke should be suppressed. May not be possible. Further, the sulfur content is more preferably 0.7% by weight or less, and further preferably 0.65% by weight or less for the same reason as described above.

The nitrogen content of the raw material coal tar pitch is preferably 0.9 to 1.5% by weight. If the nitrogen content of the raw material coal tar pitch exceeds 1.5% by weight, the nitrogen content in the pitch after hydrogenation using the apparatus of the present invention does not sufficiently decrease, so that puffing of needle coke is suppressed. May not be possible. Further, the nitrogen content is more preferably 1.3% by weight or less, and further preferably 1.2% by weight or less for the same reason as described above.

Although it is possible to reduce the sulfur content and nitrogen content in the coal tar pitch by hydrogenating with a hydrogenation treatment device described later, the above-mentioned sulfur content is required for stable hydrogenation treatment. , It is preferable to perform hydrogenation using coal tar pitch within the range of nitrogen content as a raw material.
Coal tar pitch is mostly composed of aromatic compounds, but there is an aromatic index as an index showing aromaticity. The larger the aromatic index, the more preferable, for example, 0.9 or more. In the coal tar pitch, when the aromatic index becomes small, the growth of the mesoface becomes insufficient, and the coefficient of thermal expansion (CTE) of the needle coke obtained from the hydrogenated coal tar pitch tends to be insufficiently suppressed.

The fraction of the raw material coal tar pitch at 360 ° C. or lower is preferably 8 to 30% by weight. When the fraction of the raw material coal tar pitch at 360 ° C. or lower is less than 8% by weight, the viscosity of the coal tar pitch becomes high, and a uniform hydrogenation reaction may be difficult to occur. On the other hand, when the fraction of the raw material coal tar pitch of 360 ° C. or lower exceeds 30% by weight, the hydrogenation reaction is concentrated on the light oil component in the raw material coal tar pitch, and as a result, sulfur and nitrogen in coke The reduction tends to be inadequate. The fraction of 360 ° C. or lower is preferably 9 to 20% by weight, more preferably 9.5 to 15% by weight, for the same reason as described above.

The viscosity of the raw material coal tar pitch at 100 ° C. is preferably 30 to 300 mPa · s. When the viscosity of the raw material coal tar pitch at 100 ° C. is less than 30 mPa · s, the hydrogenation reaction is concentrated on the light oil component in the raw material coal tar pitch, resulting in insufficient reduction of sulfur and nitrogen in coke. It tends to be. On the other hand, if the viscosity of the raw material coal tar pitch at 100 ° C. exceeds 300 mPa · s, the viscosity of the coal tar pitch becomes high, and a uniform hydrogenation reaction may be difficult to occur. Further, the viscosity at 100 ° C. is more preferably 100 to 250 mPa · s for the same reason as described above.

The raw material coal tar pitch preferably has a ratio (H / C) of hydrogen atoms to carbon atoms of 0.5 to 0.7.
When the H / C of the raw material coal tar pitch is less than 0.5, the amount of hydrogen consumed in the hydrogenation reaction tends to increase. On the other hand, when the H / C of the raw material coal tar pitch exceeds 0.7, the content of the aliphatic content increases, and the coefficient of thermal expansion (CTE) of the needle coke obtained from the hydrogenated coal tar pitch tends to increase. .. Further, the H / C is more preferably 0.55 to 0.68 for the same reason as described above.
In addition, "H / C" means a value measured in accordance with JIS M8819, and the measuring method described in Examples described later shall be adopted.

The specific gravity of the raw material coal tar pitch at 15 ° C. is preferably 1.15 to 1.4. Here, the specific gravity at 15 ° C. means the ratio of the density at 15 ° C. to the density of water at 4 ° C.
When the specific gravity (15 ° C./4 ° C.) of the raw material coal tar pitch is less than 1.15, the yield of coke tends to decrease and the coefficient of thermal expansion of coke tends to increase. On the other hand, when the specific gravity (15 ° C./4 ° C.) of the raw material coal tar pitch exceeds 1.4, the content of heavy components contained in the raw material coal tar pitch increases, and the coke of the raw material coal tar pitch after the hydrogenation treatment The thermal expansion coefficient of needle coke tends to increase because the growth rate of the mesoface during the conversion process is too high. Further, the specific gravity (15 ° C./4 ° C.) is more preferably 1.15 to 1.25 for the same reason as described above.
The characteristics of the raw material coal tar pitch described above are independent of each other, and it is not always necessary to combine all the characteristics.

<Separation of light oil from coal tar pitch>
In the present invention, the raw material coal tar pitch described above may be used as a raw material for hydrogenation as it is, but a light oil separated from the coal tar pitch and removed may be used as the raw material coal tar pitch ( Hereinafter, it may be referred to as "light oil separation coal tar pitch").
In the present invention, the method and apparatus for separating the light oil from the coal tar pitch are not limited, and examples thereof include centrifugation, solvent extraction, stripping, steam distillation, flash distillation, thin film distillation, atmospheric distillation, and vacuum distillation. (Not shown).
The light oil in the present invention is not limited as long as it is generally called light oil (light oil). The carbon number of the compound constituting the light oil is not limited, but is usually 36 or less, preferably 24 or less. Light oil may be a single compound, but is usually a mixture of multiple compounds.

When the light oil is separated by the above-mentioned distillation means, the substance (light fraction) obtained from the upper part of the distillation apparatus is used as the light oil. That is, if it is obtained from the upper part of the distillation apparatus, the one containing a substance other than the light oil component exemplified above is also referred to as "light oil". The temperature of the upper part of the distillation apparatus for separating the light oil is not particularly limited, but it is 400 ° C. or lower, preferably 360 ° C. or lower, more preferably 320 ° C. or lower in atmospheric distillation.
On the other hand, the heavy oil in the present invention means a component having a boiling point higher than that of the light oil defined above. The number of carbon atoms of the polymer compound constituting the heavy oil is not limited, but is usually 24 or more, preferably 36 or more. When heavy oil is obtained by the above-mentioned distillation means, the substance (heavy fraction) obtained from the lower part of the distillation apparatus is used as heavy oil. The temperature at which the heavy oil is obtained is not particularly limited, but when the atmospheric distillation is performed, it is desirable to distill at the temperature at which the above-mentioned light oil is separated.

In the present invention, the proportion of light oil separated from the coal tar pitch is not limited, but is usually 6% by weight or more, preferably 10% by weight or more, while usually 40% by weight or less, preferably 30% by weight or less. .. When the ratio of the gas oil to be separated is less than the lower limit, the amount of the gas oil separated in the distillation column is small and weeping may occur. On the other hand, if the proportion of light oil to be separated exceeds the upper limit, a large amount of heat is required to separate the light oil in the distillation column, and the diameter of the distillation column needs to be increased, which is economical. It tends to be unfavorable in terms of aspects.

The use of light oil separated from coal tar pitch is not limited, but it is not only used as fuel, but also as a raw material for carbon black and other various chemical industries, solvents, lubricants, modifiers, refrigerants (cooling oil), etc. Can be usefully used as.

In the present invention, the light oil separation coal tar pitch is not limited, but it is preferably one having the following characteristics.
The quinoline insoluble content of the light oil-separated coal tar pitch in the present invention is not limited, but is usually 0.02% by weight or less, preferably 0.01% by weight or less, and more preferably 0.008% by weight or less. .. By setting the content of the quinoline insoluble matter in the above range, the pitch-based needle coke obtained by hydrogenating the quinoline insoluble content not only shows a low puffing value, but also shows a sufficiently small coefficient of thermal expansion. I tend to be able to do it.
The lower limit of the quinoline insoluble content of the light oil-separated coal tar pitch in the present invention is not limited and is preferably a lower value, but it can be set to 0 (zero) as long as coal tar is used as a starting material. Due to the difficulty, it is usually 0.0001% by weight or more.

The sulfur content of the light oil-separated coal tar pitch in the present invention is not limited, but is usually 0.9% by weight or less, preferably 0.8% by weight or less, and more preferably 0.7% by weight or less. By setting the sulfur content in the above range, the pitch-based needle coke obtained by hydrogenating the sulfur content can not only show a low puffing value but also a sufficiently small coefficient of thermal expansion. There is a tendency.
The gas oil-separated coal tar pitch in the present invention is not limited to the lower limit of the sulfur content and is preferably a lower value, but it is difficult to set it to 0 (zero) as long as coal tar is used as a starting material. Therefore, it is usually 0.05% by weight or more.

The nitrogen content of the light oil-separated coal tar pitch in the present invention is not limited, but is usually 1.4% by weight or less, preferably 1.3% by weight or less, and more preferably 1.2% by weight or less. By setting the nitrogen content in the above range, the pitch-based needle coke obtained by hydrogenating the nitrogen content can not only show a low puffing value but also a sufficiently small coefficient of thermal expansion. There is a tendency.
The lower limit of the nitrogen content of the light oil separated coal tar pitch in the present invention is not limited and is preferably a lower value, but it is difficult to set it to 0 (zero) as long as coal tar is used as a starting material. Therefore, it is usually 0.20% by weight or more.

The fraction of the light oil-separated coal tar pitch of 360 ° C. or lower in the present invention is not limited, but is preferably 9% by weight or less. When the fraction below 360 ° C. exceeds 9% by weight, the coke yield tends to be low. Further, the fraction of 360 ° C. or lower is more preferably 7% by weight or less for the same reason as described above. On the other hand, the lower limit of the fraction at 360 ° C. or lower is preferably 0.02% by weight or more, and more preferably 0.5% by weight or more. 36
If the fraction below 0 ° C. is less than the above lower limit, the liquidus viscosity during mesoface growth tends to increase and the mesoface growth tends to be inhibited.

The viscosity of the light oil-separated coal tar pitch in the present invention at 100 ° C. is preferably 500 to 3000 mPa · s. When the viscosity at 100 ° C. is less than 500 mPa · s, it tends to be difficult to transfer the liquid when using a pump that handles a highly viscous fluid, and there is a large amount of light oil contained in the coal tar pitch, so that needle coke The coefficient of thermal expansion tends to be high. On the other hand, if the viscosity at 100 ° C. exceeds 3000 mPa · s, the fluidity becomes extremely low, which tends to make transportation by piping difficult. Further, the viscosity at 100 ° C. is more preferably 350 to 2500 mPa · s for the same reason as described above.

The light oil-separated coal tar pitch in the present invention preferably has a ratio (H / C) of hydrogen atoms to carbon atoms of 0.5 to 0.8. When the H / C is less than 0.5, the amount of heavy components is large, the growth of the mesoface is hindered, and the coefficient of thermal expansion (CTE) of the obtained needle coke tends to be high. On the other hand, when the H / C exceeds 0.8, the content of the aliphatic compound tends to increase, and the coefficient of thermal expansion of the obtained needle coke tends to increase. Further, the H / C is more preferably 0.55 to 0.7 for the same reason as described above.

The specific gravity of the light oil-separated coal tar pitch in the present invention at 15 ° C. is preferably 1.0 to 1.4. When the specific gravity (15 ° C./4 ° C.) of the light oil separated coal tar pitch is less than 1.0, the coke yield tends to be low. On the other hand, when the specific gravity (15 ° C./4 ° C.) of the light oil-separated coal tar pitch exceeds 1.4, the content of heavy components is high and the growth of mesoface tends to be inhibited. Further, the specific gravity (15 ° C./4 ° C.) is more preferably 1.1 to 1.3 for the same reason as described above.
The characteristics of the above-mentioned light oil-separated coal tar pitch are independent of each other, and it is not always necessary to have all the characteristics.

As described above, a separation device for separating light oil from coal tar pitch is provided, and good characteristics are obtained by performing a hydrogenation reaction using the light oil separation coal tar pitch as a raw material using a hydrogenation treatment device described later. Needle coke with has a tendency to be obtained.
Needle coke is thought to have a low coefficient of thermal expansion due to its needle-shaped crystal structure. This developed needle-like structure is thought to be formed by the generation of gas, especially hydrogen, from the aromatic ring generated during the formation of mesofaces. Therefore, by distilling off light oil having a low contribution to coking and increasing the viscosity at the time of gas generation, the growth of mesoface is promoted more efficiently, and the coefficient of thermal expansion of the obtained needle coke is lowered. It is considered that there is a high tendency to cause it.

Light oil separation The coal tar pitch has a higher viscosity and a lower fluidity than before the light oil was separated. Therefore, when this is used as the raw material coal tar pitch, the contact efficiency with the catalyst is lowered in the hydrogenation treatment, and the desulfurization rate and the denitrification rate may be lowered. However, in the present invention, as will be described later, the above problem can be solved by using the device configuration in which the raw material coal tar pitch and the light oil separated from the hydrogenated coal tar pitch are used together as the raw material to be supplied to the hydrogenation treatment device. be able to. Therefore, in the apparatus of the present invention, the light oil-separated coal tar pitch can be effectively used as the raw material coal tar pitch.

<Petroleum-based heavy oil>
In the present invention, as a raw material to be hydrogenated, a device configuration capable of using a petroleum-based heavy oil mixed with the above-mentioned raw material coal tar pitch may be used. Further, the apparatus may be configured as a raw material for mixing the raw material coal tar pitch and petroleum-based heavy oil, and then separating and hydrogenating the light oil. Further, the apparatus may be configured as a raw material for mixing and hydrogenating light oil-separated coal tar pitch and petroleum-based heavy oil.

Petroleum-based heavy oils to be mixed and used are not limited, but for example, liquid catalytic decomposition oil, atmospheric distillation residual oil, vacuum distillation residual oil, shale oil, tar sand bitumen, orinocotal, coal liquefied oil, ethylene bottom oil and Examples include heavy oil obtained by hydrorefining these. In addition to the above, relatively light oils such as straight-run gas oil, vacuum gas oil, desulfurization gas oil, and desulfurization gas oil may be further contained. Among these, cracked cracked oil and atmospheric distillation residual oil are particularly preferable because they contain a relatively large amount of aromatic components.

The sulfur content of the petroleum-based heavy oil is preferably 1.0% by weight or less, and more preferably 0.5% by weight or less. The nitrogen content of the petroleum-based heavy oil is preferably 0.7% by weight or less, and more preferably 0.4% by weight or less. If the sulfur content and nitrogen content of the petroleum-based heavy oil to be mixed exceed the above upper limit values, the puffing of needle coke may not be sufficiently suppressed.

The mixing ratio of petroleum-based heavy oil is not limited, and is appropriately optimized by calculating from the nitrogen content and sulfur content in coal tar or coal tar pitch, and the nitrogen content and sulfur content in petroleum-based heavy oil. It is preferable to mix the mixed oil so that the sulfur content is 1.0% by weight or less and the nitrogen content is 0.9% by weight or less. The lower limit of each component in the mixed oil is not limited, but it is usually preferable to mix in a proportion such that the sulfur content is 0.3% by weight or more and the nitrogen content is 0.1% by weight or more. Specifically, it is preferable to mix coal tar or coal tar pitch in a proportion of 50 to 80% by weight and petroleum-based heavy oil in a proportion of 50 to 20% by weight. In general, petroleum-based heavy oil tends to have a lower nitrogen content and a higher sulfur content than coal tar, but the nitrogen content and sulfur content after mixing the two are mixed and used so as to be within the above range. As a result, the effects of the present invention can be effectively exerted.

When the above petroleum-based heavy oil contains a large amount of saturated hydrocarbons, especially aliphatic components, a cross-linking reaction occurs in addition to polymerization and polycondensation of aromatic components, so that crystals having a three-dimensional structure grow and mesofaces are formed. It is believed that it does not grow sufficiently, resulting in a large thermal expansion coefficient. Since the raw material coal tar pitch used in the apparatus of the present invention is made from coal tar, it has extremely high aromaticity and is suitable as a raw material for needle coke, but as a petroleum-based heavy oil used as a mixed raw material oil. Although the proportion of aromatic components is smaller than that of coal tar, the above-mentioned cracked cracking oil and atmospheric distillation residual oil are preferable because they have a relatively large amount of aromatic components.

[2. Hydrogenation treatment equipment]
In the apparatus of the present invention, the raw material coal tar pitch (including the case where petroleum-based heavy oil is mixed and used as described above) is charged into the hydrogenation treatment apparatus and hydrogenated to hydrogenate the raw material coal tar pitch. It can be a coal tar pitch (see FIG. 1).
The apparatus of the present invention has a mechanism for supplying the light oil separated by the separation apparatus described later to the hydrogenation treatment apparatus together with the raw material coal tar pitch, and this feature will be described later.
Further, as a raw material to be supplied to the hydrogenation step, a raw material other than the above (hereinafter, may be referred to as “other raw material”) may be used in combination. Other raw materials are not limited, but from the viewpoint of low hydrogen consumption, a carbon-based compound having a high degree of saturation and a carbon-based compound having a low aromaticity are preferably used.

In the present invention, the hydrogenation treatment apparatus is an apparatus for reducing the sulfur concentration and the nitrogen concentration in the pitch-based raw material oil by using a catalyst in the presence of high-pressure hydrogen.
The specific method of the hydrogenation treatment apparatus is not limited, but a continuous reaction type apparatus is preferable from the viewpoint of reactivity and productivity. The catalyst layer can be a fluidized bed, a fixed bed, or a combination thereof, but a fixed bed type is preferable from the viewpoint of easy long-term operation and economic efficiency such as construction cost. That is, a continuous fixed bed type hydrogenation treatment apparatus is suitable for the present invention. The batch reactor may not be preferable because of its low hydrogenation reaction rate.
The shape and material of the hydrogenation treatment apparatus are not limited as long as they are designed to withstand high-temperature reactions containing hydrogen.

Usually, the raw material coal tar pitch is transferred at a temperature of about 100 to 280 ° C. On the other hand, the hydrogenation reaction by the hydrogenation treatment apparatus is usually carried out at a temperature of about 300 to 450 ° C. as described later. Therefore, the raw material coal tar pitch and hydrogen need to be heated to a temperature higher than the temperature at which the hydrogenation reaction starts and supplied to the hydrogenation treatment apparatus. Therefore, it is preferable to use a device provided with a device for heating the raw material to be supplied to the hydrogenation treatment device (not shown, hereinafter may be referred to as a “heating device”). The type of the heating device is not limited, and examples thereof include a heat exchanger and a heating furnace using heat medium oil or steam as a heat source.

On the other hand, as will be described later, the light oil separated by the separation device is usually discharged at a high temperature of about 250 to 400 ° C. Therefore, it is also preferable to use light oil separated by a separating device as the heat medium of the heat exchanger.
Further, it is also preferable to heat the raw material by mixing the raw material coal tar pitch and the light oil recycled at a high temperature. By this method, it can be used as a substitute for the heating device or a means for complementing the function of the heating device. Further, in the case of this method, the cooling device shown in FIG. 1 may not be used, or the scale may be reduced.

The method of supplying hydrogen is not limited, but when it is supplied in the same direction as the flow of the raw material coal tar pitch, it may be supplied from one place or divided into a plurality of places. Further, a part of hydrogen may be mixed with the raw material coal tar pitch, and the remaining hydrogen may be supplied to a hydrogenation treatment apparatus through which the raw material coal tar pitch flows during the reaction, but hydrogen is mixed in advance with the raw material coal tar pitch. It is desirable to supply the hydrogenated product in a state. More specifically, as shown in FIG. 1, in the hydrided coal tar pitch manufacturing apparatus of the present invention, the hydride processing apparatus has a line for supplying the raw material coal tar pitch and hydrogen, and the line is called. It is preferable that the line for supplying the tar pitch and the line for supplying hydrogen are previously merged, and in such a device, entrainment or flooding (the supplied raw material coal tar pitch is contained in the reactor. It is preferable from the viewpoint of preventing a phenomenon in which hydrogen rising from the lower side and gas generated by the reaction cause the hydrogen to be lifted to the upper side of the hydrotreating apparatus).

Further, hydrogen may be supplied in the direction opposite to the flow of the raw material coal tar pitch as shown in FIG. 2, or can be supplied from the vicinity of the outlet of the hydrogenation treatment apparatus. In this case, the hydrogen supply location may be one location or may be divided into a plurality of locations for supply. A part of hydrogen may be supplied from the outlet of the hydrogenation treatment device, and the remaining hydrogen may be supplied to the hydrogenation treatment device through which the raw material coal tar pitch during the reaction flows, or may be discharged from the outlet of the hydrogenation treatment device. It is possible to mix hydrogenated coal tar pitch and hydrogen and supply only hydrogen to the hydrogenation treatment device, but in order to prevent backflow of hydrogenated coal tar pitch, from the vicinity of the outlet of the hydrogenation treatment device. It is desirable to supply hydrogen. More specifically, in the hydrogenated coal tar pitch manufacturing apparatus of the present invention, the hydrogenation treatment apparatus has a raw material coal tar pitch supply port and a hydrogen supply port, and at least one hydrogen supply port is provided. , It is preferable that the raw material is provided on the downstream side of the supply port of the raw material coal tar pitch, and in such an apparatus, the hydrogenation reaction can proceed more satisfactorily in the hydrogenation treatment apparatus. preferable.

The method of mixing the raw material coal tar pitch and hydrogen is not limited, and these may be independently supplied to the hydrogenation treatment apparatus or may be supplied to the hydrogenation treatment apparatus in a premixed state, but the latter Is preferable.
When the raw material coal tar pitch and hydrogen are independently supplied to the hydrogenation treatment equipment, if low-temperature hydrogen is mixed with the high-temperature raw material coal tar pitch, the temperature of the raw material coal tar pitch drops, so hydrogenation The reactivity of the reaction may decrease, or it may become difficult to supply the raw material coal tar pitch to the hydrogenation treatment apparatus. Therefore, it is preferable to heat and supply hydrogen as well.

On the other hand, when the raw material coal tar pitch and hydrogen are mixed in advance and supplied to the hydrogenation treatment apparatus, the above-mentioned problems can be solved. In the case of this method, it is desirable to mix the raw material coal tar pitch and hydrogen immediately before the heating device or the hydrogenation treatment device. When mixing both fluids only by connecting the hydrogen supply pipe and the raw material coal tar pitch supply pipe, for the above reason, the length of the pipe from the place where both fluids are mixed to the heating device or the hydrogenation treatment device. Is desirable to be as short as possible.

The material of the pipe for charging the raw material coal tar pitch into the hydrogenation treatment apparatus is not limited as long as it does not cause corrosion due to the raw material coal tar pitch, and can be appropriately selected and used. On the other hand, for the piping for charging hydrogen into the hydrogenation treatment device, it is necessary to select a material that can withstand corrosion by hydrogen and does not allow hydrogen to permeate. Further, when the raw material coal tar pitch and hydrogen are mixed and charged into the hydrogenation treatment apparatus, it is preferable that the material of the piping in that range is the same as that of the piping for transferring hydrogen.

In the present invention, the method of hydrogenating the raw material coal tar pitch using the hydrogenation treatment apparatus is not limited, but a specific method will be described below.
Examples of the catalyst used in the hydrogenation treatment include a Ni-Mo-based catalyst, a Co-Mo-based catalyst, a Ni-Co-Mo-based catalyst, or a catalyst in which these are combined, and commercially available products may be used for these. .. Among these, Ni-Mo-based catalysts are preferable because they have high desulfurization and denitrification activities and can suppress hydrogen consumption.

The temperature of the hydrogenation treatment is not limited, but is usually 300 to 450 ° C. When the temperature of the hydrogenation treatment is less than 300 ° C., the desulfurization rate and the denitrification rate tend to decrease, and the suppression of needle coke puffing tends to be insufficient. On the other hand, if the temperature exceeds 450 ° C., problems such as a decrease in catalyst life tend to occur. The temperature of the hydrogenation treatment is preferably 350 to 420 ° C., more preferably 360 ° C. to 400 ° C. for the same reason as described above.

The hydrogen / pitch flow rate ratio in the hydrogenation treatment is not limited, but is usually 100 to 700 Nm ³ / m ³ per 1 m ^{3 of} pitch. When the hydrogen / pitch flow rate ratio is less than 100 Nm ³ / m ³ , the desulfurization rate and denitrification rate tend to decrease due to insufficient hydrogenation, and the suppression of needle coke puffing tends to be insufficient. .. Furthermore, the CTE of needle coke tends to be high due to insufficient growth of the mesoface. On the other hand, when the hydrogen / pitch flow rate ratio exceeds 700 Nm ³ / m ³ , hydrogenation tends to proceed excessively, lightening progresses, and the yield of coke tends to decrease. The hydrogen / pitch flow rate ratio in the hydrogenation treatment is preferably 200 to 600 Nm ³ / m ³ and more preferably 250 to 500 Nm ³ / m ³ for the above reasons.

The partial pressure of hydrogen in the hydrogenation treatment is not limited, but is usually 5 to 20 MPa. If the hydrogen partial pressure is less than 5 MPa, the desulfurization rate and denitrification rate due to the hydrogenation reaction are small, and as a result, the puffing suppression of needle coke tends to be insufficient. Further, when the partial pressure of hydrogen exceeds 20 MPa, the decomposition of the pitch-based raw material oil proceeds too much, so that not only the yield of coke when coked is lowered, but also the coefficient of thermal expansion of coke tends to increase. is there.
For the same reason as described above, the hydrogen partial pressure in the hydrogenation treatment is preferably 8 MPa or more, more preferably 10 MPa or more, further preferably 12 MPa or more, and preferably 18
It is MPa or less, more preferably 16 MPa or less.

The liquid space velocity (LHSV) in the hydrogenation treatment is not limited, but is usually 0.1 to 2.0 h- ¹ . When the liquid space velocity (LHSV) exceeds 2.0 h- ¹ , sufficient hydrogenation is not performed, so that the desulfurization rate and denitrification rate decrease, and the suppression of needle coke puffing tends to be insufficient. .. Furthermore, the CTE of needle coke tends to be high due to insufficient growth of the mesoface. On the other hand, when the liquid space velocity (LHSV) is less than 0.1h- ¹ , hydrogenation proceeds excessively, lightening progresses, and the yield of coke tends to decrease. The liquid space velocity in the hydrogenation treatment is preferably 0.3 to 1.6 h ^-1 , more preferably 0.3 to 1.3 h ^-1 , and even more preferably 0.5 to 0.5 for the same reason as described above. It is 1.0h ^-1 .

The conditions for the hydrogenation treatment described above are independent of each other, and it is not always necessary to combine all the conditions.
By using the hydrogenation treatment apparatus of the present invention and setting the reaction temperature, hydrogen / pitch flow rate ratio, hydrogen partial pressure, and liquid space velocity (LHSV) within the above ranges, optimum hydrogenation proceeds and puffing is sufficiently suppressed. The desulfurization rate and denitrification rate are such that the obtained needle coke can be obtained, and further, it is possible to promote the growth of a mesoface sufficient to obtain needle coke having a low coefficient of thermal expansion.

[3. Separator]
In the present invention, the coal tar pitch hydrogenated by the hydrogenation treatment apparatus is separated into the hydrogenated coal tar pitch and the light oil by the separation apparatus. In the present invention, the light oil separated from the coal tar pitch hydrogenated by the hydrogenation treatment apparatus may be referred to as "hydrogenated oil".
The specific method of the separation device is not limited, and examples thereof include centrifugation, solvent extraction, stripping, steam distillation, flash distillation, thin film distillation, atmospheric distillation, and vacuum distillation. The separation device is appropriately selected according to these methods, and specifically, a centrifuge, an extractor, a gas-liquid separator, various distillation columns such as a steam distillation column and an atmospheric distillation column, a thin film distillation column, and the like are used. Be done. Of these, a distillation column or a gas-liquid separator is preferable.

In the present invention, the method for separating the hydrogenated coal tar pitch and the hydrogenated oil using a separation device is not limited, but a specific method will be described below.
When the hydrogenated oil is separated by atmospheric distillation, the upper temperature of the distillation apparatus (distillation column) is not limited, but is usually 400 ° C. or lower, preferably 380 ° C. or lower, and more preferably 360 ° C. or lower.
The proportion of hydride oil separated from the coal tar pitch obtained by the hydrogenation treatment is not limited, but is usually 2% by weight or more, preferably 10% by weight or more, while usually 40% by weight or less, preferably 35% by weight. It is less than% by weight. If the proportion of hydrogenated oil to be separated is less than the above lower limit, the amount of hydrogenated oil to be recycled to the hydrogenation treatment apparatus is reduced, so that the effect of lowering the viscosity of the raw coal tar pitch and the reaction heat in the hydrogenation reaction are removed. In some cases, the effects of the present invention, such as the effect of hydrogenation, cannot be fully exerted. On the other hand, when the ratio of the hydrogenated oil to be separated exceeds the upper limit value, the production efficiency of the hydrogenated coal tar pitch tends to decrease.

In the separation device, not only the hydrogenated oil can be separated from the coal tar pitch obtained by the hydrogenation treatment, but also the reaction gas generated by the hydrogenation reaction and the unreacted hydrogen can be separated. The number of separation devices installed is not particularly limited, but when there is a large amount of reaction gas or unreacted hydrogen, a plurality of separation devices are installed and the pressure of the separation device is changed stepwise to hydrogenate the above-mentioned gas. It is desirable to separate the oil to obtain hydrogenated oil. In this case, a gas discharge circuit that discharges only the above-mentioned gas may be provided.

By coking the hydrogenated coal tar pitch obtained by separating the hydrogenated oil with a separating device, puffing can be sufficiently suppressed and needle coke having a small coefficient of thermal expansion can be obtained.

<Hydrogenated oil>
The characteristics of the hydrogenated oil separated by the separation device are not limited, but as will be described later, by recycling to the hydrogenation treatment device, the effect of lowering the viscosity of the raw coal tar pitch and the heat of reaction in the hydrogenation reaction are removed. It is desirable to have the following characteristics because it produces the following effects.
It is not necessary to use the entire amount of the hydrogenated oil in the recycling process described later, and a part of the hydrogenated oil can be extracted and used for other purposes. Specifically, hydrogenated oil can also be usefully used as a refrigerant (cooling oil), a raw material for various chemical industries, a solvent, a lubricant, a modifier, a fuel, and the like. The circuit for extracting and discharging a part of the hydrogenated oil will be described later.

The sulfur content of the hydrogenated oil is preferably 0.6% by weight or less, and more preferably 0.3% by weight or less. When the sulfur content in the hydrogenated oil exceeds 0.6% by weight, the desulfurization reaction generated in the hydrogenation treatment apparatus becomes excessive, and the amount of hydrogen consumed in the hydrogenated oil tends to increase.
The nitrogen content of the hydrogenated oil is preferably 0.7% by weight or less, and more preferably 0.4% by weight or less. When the nitrogen content in the hydrogenated oil exceeds 0.7% by weight, the denitrification reaction generated in the hydrogenation treatment apparatus becomes excessive, and the amount of hydrogen consumed in the hydrogenated oil tends to increase.
The ratio of the number of hydrogen atoms to the number of carbon atoms (H / C) of the hydride oil is preferably 0.8 or more, and more preferably 1.0 or more. When the H / C of the hydride oil is less than 0.8, the amount of hydrogen used for hydrogenation of the hydride oil tends to increase, and the reaction efficiency tends to decrease.

The viscosity of the hydrogenated oil at 100 ° C. is preferably 6 mPa · s or less, and more preferably 2 mPa · s or less.
If the viscosity of the hydrogenated oil at 100 ° C. exceeds 6 mPa · s, it tends to be difficult to mix with the raw material coal tar pitch. Therefore, when it is used for the purpose of lowering the viscosity of the raw material coal tar pitch, the viscosity tends not to be lowered sufficiently, and when it is used as a refrigerant in a hydrogenation reaction, it flows in the hydrogenation treatment apparatus. It is not sufficiently mixed with the reaction solution (raw material coal tar pitch or hydrogenated coal tar pitch), and there is a tendency that uniform cooling of the hydrogenation treatment apparatus is not performed.

The specific gravity of the hydrogenated oil at 15 ° C. is preferably 0.8 to 1.2.
When hydride oil is used for the purpose of lowering the viscosity of the raw material coal tar pitch, if the specific gravity of the hydride oil is less than 0.8 or more than 1.2, the difference in specific gravity from the raw material coal tar pitch is large. , Tends to be difficult to mix with raw coal tar pitch. Therefore, the hydrogenated oil is not sufficiently mixed with the raw material coal tar pitch, and the viscosity of the raw material coal tar pitch tends not to be sufficiently lowered.
Further, when hydrogenated oil is used as a hydrogenator in a hydrogenation reaction, if the specific gravity of the hydrogenated oil is less than 0.8, there are many light boiling components, vaporization occurs in the hydrogenation treatment apparatus, and uniform cooling is achieved. On the other hand, when the specific gravity of the hydrogenated oil is 1.2 or more, there are many heavy components and the reaction solution (raw material coal tar pitch or hydrogenated coal tar pitch) flowing in the hydrogenation treatment apparatus. ), And there is a tendency that uniform cooling of the hydrogenation treatment equipment is not performed.

[4. Recycling circuit]
The present invention has a recycling circuit that supplies light oil (hydrogenated oil) separated by a separation device to a hydrogenation treatment device. That is, at least the raw material coal tar pitch and hydrogenated oil are supplied to the hydrogenation treatment apparatus.
By supplying the hydrogenated oil to the hydrogenation treatment apparatus, it has the effect of lowering the viscosity of the raw material coal tar pitch and also has the effect of controlling the reaction temperature of the hydrogenation step, which is an exothermic reaction. Since the hydrogenated oil is a light oil that has already been hydrogenated, the reaction activity is low even if it is subjected to the hydrogenation treatment apparatus again. Moreover, since it is not a foreign substance with respect to the target coal tar pitch, there is no problem of forming a circulation circuit. Therefore, it is effective to provide a separation device and a recycling circuit in order to exhibit the above two effects while suppressing the consumption of hydrogen.
The material of the piping constituting the recycling circuit is not limited as long as it is not corroded by hydrogenated oil, and can be appropriately selected and used.

The method and location of supplying hydrogenated oil to the hydrogenation process are not limited. Therefore, the line configuration of the recycling circuit is not limited.
The recycling circuit may have a structure in which hydrogenated oil is mixed with a raw material coal tar pitch and supplied to the hydrogenation treatment apparatus, or these may be independently supplied to the hydrogenation treatment apparatus. The mechanism for mixing the raw material coal tar pitch and the hydrogenated oil and supplying them to the hydrogenation treatment apparatus is not limited, and it may be a mixing means such as a stirring tank, or only the lines (piping) are merged. It may be a structure. Further, the structure may be such that the hydrogenated oil is supplied in the middle of the hydrogenation treatment apparatus, that is, in the middle of the hydrogenation reaction.
The recycling circuit may be a circuit for supplying light oil to a plurality of locations of the hydrogenation treatment apparatus.

When recycling hydrogenated oil for the purpose of reducing the viscosity of the raw coal tar pitch, it is desirable to mix the raw coal tar pitch and the hydrogenated oil with a structure that only merges the lines (pipes) (Fig. 1). reference). Furthermore, it is desirable that the piping and the like are designed so that the fluid after merging them becomes a turbulent flow. The location of the mixing mechanism is not limited, but it is desirable that it is immediately before the hydrogenation treatment device.

On the other hand, when the hydrogenated oil is recycled for the purpose of controlling (adjusting) the reaction temperature of the hydrogenation process, not only the structure of supplying the hydrogenated oil together with the raw material coal tar pitch at the inlet of the hydrogenation treatment device but also the hydrogenation treatment device It is also preferable that the structure is supplied in the middle of the above (see FIG. 3).
As described above, since the hydrogenation reaction by the hydrogenation treatment apparatus is a very high temperature and is an exothermic reaction, it may be necessary to remove (cool) the reaction heat. For this reason, by adopting a structure that supplies hydrogenated oil adjusted to a temperature lower than the reaction temperature at the relevant location in the middle of the hydrogenation treatment device, it is possible to efficiently cool and control the reaction temperature and reaction rate. Can be done. The position of the hydrogenation treatment device that supplies the hydrogenated oil is not limited, but for example, in the case of a device in which the catalyst layer is installed in a shelf shape, the structure in which the hydrogenated oil is charged at the position of the catalyst layer is Can be mentioned. The hydrogenated oil may be charged into one place in the apparatus, or may be charged from two or more places.

The apparatus of the present invention may include a temperature sensor in the hydrogenation treatment apparatus and may have a function of controlling the amount of hydrogenated oil supplied to the hydrogenation treatment apparatus according to the temperature information from the temperature sensor (Fig.). Not shown). This function is particularly preferable when the hydrogenated oil is recycled for the purpose of controlling the reaction temperature of the hydrogenation step. It is preferable that the apparatus of the present invention has this function because the temperature of the hydrogenation reaction can be efficiently controlled. When the hydrogenated oil is supplied to a plurality of locations of the hydrogenation treatment apparatus by branching the recycling circuit, the hydrogenation treatment apparatus is provided with a plurality of temperature sensors, and the temperature information from the plurality of temperature sensors is provided. It may be a function of controlling each supply amount according to the above.

In addition, in order to remove (cool) the heat of the hydrogenation reaction, means other than the above recycling circuit can be used in combination. Specifically, a device configuration for supplying a refrigerant other than hydrogenated oil (hereinafter, may be referred to as “other refrigerant”) to the hydrogenation treatment device may be added. Other refrigerants are not limited, and examples thereof include hydrogen gas, other recycled gases, and hydrocarbons. When hydrocarbons are used as other refrigerants, saturated hydrocarbons are preferable because they are less susceptible to hydrogenation reactions.

A cooling device may be provided in the recycling circuit. By providing a cooling device in the recycling circuit, the hydrogenated oil can be cooled and supplied to the hydrogenation treatment device. When there are a plurality of circuits for supplying hydrogenated oil to the hydrogenation processing apparatus, a cooling device may be provided in each circuit, or a cooling device may be provided in a position before the recycling circuit branches. The method and structure of the cooling device are not limited, and examples thereof include a heat exchanger using a refrigerant and a water tube boiler using a fluid as a heat source.
By providing a cooling device in the recycling circuit, it is possible to supply low-temperature hydrogenated oil to the hydrogenation treatment device. Therefore, especially when recycling hydrogenated oil for the purpose of controlling the reaction temperature of the hydrogenation process. It is effective. In this case, it is desirable to cool the hydrogenated oil to a lower temperature because the amount of recycled hydrogenated oil can be reduced.

Further, the recycling circuit shown in FIG. 4 may be used. That is, the recycling circuit is branched, and the cooling device is not used (or the scale is reduced) in the circuit for the purpose of reducing the viscosity of the raw material coal tar pitch, and the reaction temperature of the hydrogenation step is controlled. A cooling device may be provided in the target circuit.

[5. Discharge circuit]
As described above, in the present invention, it is not necessary to supply the entire amount of the hydrogenated oil separated by the separating device to the hydrogenation processing device, and a circuit for extracting and discharging a part of the hydrogenated oil may be provided (FIG. 1). reference). The method of discharging the hydrogenated oil is not limited, but if the pressure of the hydrogenated oil flowing through the recycling circuit is sufficiently high, it is sufficient to branch the flow path such as piping. If the pressure of the hydrogenated oil flowing through the recycling circuit is not sufficiently high, the pressure may be increased by a transfer pump or the like, or the oil may be discharged to a container such as a tank once. Further, a method in which the supply destination of the hydrogenated oil can be switched by using a three-way valve, a four-way valve, a shutoff valve, or the like may be used. Here, the type of valve is not limited, and examples thereof include a ball valve, a gate valve, a glove valve, a butterfly valve, and a diaphragm valve. Further, the hydrogenated oil may be supplied to a structure capable of controlling distribution to the hydrogenation treatment apparatus and the discharge circuit. When performing such control, an automatic valve that adjusts the opening / closing or opening degree of a valve that adjusts the amount of hydrogenated oil supplied to each device while monitoring the discharge flow rate to each device, hydrogenation processing An automatic valve that opens / closes or adjusts the opening / closing of a valve that discharges hydrogenated oil from the recycling circuit while monitoring the temperature of the apparatus, or a back pressure valve that opens / closes at a constant pressure may be provided.
The supply destination of the hydrogenated oil discharged from the discharge circuit is arbitrary, and may be a storage tank or a manufacturing facility. Further, the discharge circuit may discharge the reaction gas or unreacted hydrogen gas generated by the hydrogenation reaction separated by the separation device, or a gas discharge circuit for discharging only these gases may be provided for hydrogenation. The oil and the above-mentioned gas may be discharged separately.

[6. Hydrogenated coal tar pitch]
The various characteristics of the hydrogenated coal tar pitch obtained by separating from the hydrogenated oil by the separating device as described above are not limited, but those having the following characteristics are preferable. Pitch-based needle coke obtained from these values of coal tar pitch hydride as a raw material is preferable because it not only exhibits a low puffing value but also a sufficiently small coefficient of thermal expansion.

The hydrogenated coal tar pitch obtained by the production apparatus of the present invention has a quinoline insoluble content of preferably 0.02% by weight or less, more preferably 0.01% by weight or less, still more preferably 0.005% by weight. It is less than or equal to, and particularly preferably 0.003% by weight or less. By setting the content of the quinoline insoluble matter in the above range, the pitch-based needle coke obtained from this can show not only a low puffing value but also a sufficiently small coefficient of thermal expansion. ..
The hydrogenated coal tar pitch obtained by the production apparatus of the present invention is not limited to the lower limit of the quinoline insoluble content and is preferably a lower value, but is 0 (zero) as long as the coal tar pitch is used as a raw material. Since it is difficult to make it, it is usually 0.0001% by weight or more.

The hydrogenated coal tar pitch obtained by the production apparatus of the present invention has a sulfur content of preferably 0.3% by weight or less, and more preferably 0.25% by weight or less. By setting the sulfur content in the above range, the pitch-based needle coke obtained by using this as a raw material can not only show a low puffing value but also a sufficiently small coefficient of thermal expansion.
The hydrogenated coal tar pitch obtained by the production apparatus of the present invention is not limited to the lower limit of the sulfur content and is preferably a lower value, but it is 0 (zero) as long as the coal tar pitch is used as a raw material. It is usually more than 0.05% by weight because it is difficult to do.

The hydrogenated coal tar pitch obtained by the production apparatus of the present invention has a nitrogen content of preferably 0.90% by weight or less, more preferably 0.85% by weight or less, still more preferably 0.80% by weight or less. It is particularly preferably 0.75% by weight or less. By setting the nitrogen content in the above range, the pitch-based needle coke obtained by using this as a raw material can not only show a low puffing value but also a sufficiently small coefficient of thermal expansion.
The hydrogenated coal tar pitch obtained by the production apparatus of the present invention is not limited to the lower limit of the nitrogen content and is preferably a lower value, but it is set to 0 (zero) as long as the coal tar pitch is used as a raw material. Since it is difficult to do so, it is usually 0.20% by weight or more.

The fraction of the hydrogenated coal tar pitch obtained by the production apparatus of the present invention at 360 ° C. or lower is preferably 40% by weight or less. When the fraction of the hydrogenated coal tar pitch at 360 ° C. or lower exceeds 40% by weight, the coke yield tends to be low. Further, for the fraction of 360 ° C. or lower, the upper limit is more preferably 35% by weight or less for the same reason as described above. On the other hand, the lower limit of the distillate of the hydrogenated coal tar pitch at 360 ° C. or lower is preferably 2% by weight or more, more preferably 10% by weight or more, and further preferably 15% by weight or more. If the fraction below 360 ° C. is less than the above lower limit, the liquidus viscosity during mesoface growth tends to increase and the mesoface growth tends to be inhibited.

The viscosity of the hydrogenated coal tar pitch obtained by the production apparatus of the present invention at 100 ° C. is preferably 50 to 500 mPa · s. When the viscosity of the hydrogenated coal tar pitch at 100 ° C. is less than 50 mPa · s, a large amount of light oil is contained in the hydrogenated coal tar pitch, and the coefficient of thermal expansion of needle coke tends to be high. On the other hand, when the viscosity of the hydrogenated coal tar pitch at 100 ° C. exceeds 500 mPa · s, the liquidus viscosity during the growth of the mesophase tends to be high, the growth of the mesoface is inhibited, and the coefficient of thermal expansion tends to be high. Further, the viscosity at 100 ° C. is more preferably 80 to 200 mPa · s for the same reason as described above.

The hydrogenated coal tar pitch obtained by the production apparatus of the present invention preferably has a ratio (H / C) of hydrogen atoms to carbon atoms of 0.8 or more. When the H / C of the hydrogenated coal tar pitch is less than 0.8, the formation of naphthenic rings is small, the liquidus viscosity during mesoface growth is high, and the coefficient of thermal expansion (CTE) of the obtained needle coke is high. Tend. Also,
The upper limit of H / C is preferably 1.2 or less.

The specific gravity of the hydrogenated coal tar pitch obtained by the production apparatus of the present invention at 15 ° C. is preferably 1.0 to 1.2. When the specific gravity (15 ° C./4 ° C.) of the hydrogenated coal tar pitch is less than 1.0, the coke yield tends to be low. On the other hand, when the specific gravity (15 ° C./4 ° C.) of the hydrogenated coal tar pitch exceeds 1.2, the content of heavy components is large and the growth of mesoface tends to be inhibited. Further, the specific gravity (15 ° C./4 ° C.) is more preferably 1.08 to 1.19 for the same reason as described above.

Conventionally, as long as coal tar pitch is used as a raw material, it has been extremely difficult to obtain coal tar within the range of the above-mentioned characteristics, but in the present invention, as described above, the hydrogenation treatment apparatus and separation A hydrogenated coal tar pitch satisfying the above-mentioned characteristics can be obtained by configuring the device with the device and the recycling circuit.
The characteristics of the hydrogenated coal tar pitch described above are independent of each other, and it is not always necessary to combine all the characteristics.

[7. Coke]
By coking the hydrogenated coal tar pitch obtained by the production apparatus of the present invention, it is possible to obtain a pitch-based needle coke having a small coefficient of thermal expansion and sufficiently suppressed puffing. The production of needle coke will be described below.
The method for coking the hydrided coal tar pitch obtained by the production apparatus of the present invention is not limited, and examples thereof include a delayed caulking method, a bisbraking method, a flexi caulking method, and an Eureka process. The delayed caulking method is preferable from the viewpoint of coke productivity and quality stability.

In the delayed coking method, the hydrogenated coal tar pitch rapidly passes through the heating tube while being heated, and is introduced into the coke drum to cause coking. The caulking conditions are not particularly limited, but the temperature is preferably 400 to 600 ° C, more preferably 450 to 550 ° C. The caulking time is preferably 18-72 hours, more preferably 20-40 hours.
Further, it is preferable to calcinate the coke thus obtained in a rotary kiln, a shaft furnace or the like. The temperature at the time of calcination is preferably 1000 to 1500 ° C., and the time is preferably 1 to 6 hours.

As the raw material used for coking, other raw materials may be used in combination with the hydrogenated coal tar pitch obtained by the production apparatus of the present invention. Such raw materials are not limited, and examples thereof include petroleum-based heavy oils. The petroleum-based heavy oil used in combination with the hydrogenated coal tar pitch is not limited, and examples thereof include those exemplified as the petroleum-based heavy oil that can be used together with the raw material coal tar pitch during the cracking treatment described above. Of these, liquid catalytic cracking oil and atmospheric distillation residual oil are particularly preferable.
The mixing ratio of the hydrogenated coal tar pitch and other raw materials is not limited, but the hydrogenated coal tar pitch is usually used at a ratio of 50% by weight or more, preferably 60% by weight or more, and more preferably 70% by weight or more. Is preferable.

Using the hydrogenated coal tar pitch obtained by the production apparatus of the present invention, the pitch-based needle coke obtained as described above has a low coefficient of thermal expansion and puffing because the content ratios of sulfur and nitrogen are low. Can be a pitch-type needle coke in which is sufficiently suppressed. Specifically, the sulfur content of the pitch-based needle coke can be 0.3% by weight or less, further 0.15% by weight or less, and the nitrogen content can be 0.8% by weight or less, further 0.6% by weight. It can be less than or equal to%.

The resulting pitch-based needle coke has a coefficient of thermal expansion (CTE) of 3.4 × 10 ^-7.
It is / ° C. or lower, further 3.2 × 10 ^-7 / ° C. or lower, and the puffing can be 3.4% or lower, further 3.0% or lower. Here, the puffing value means the elongation of the dimensions of the test piece when the temperature is raised from room temperature to 2600 ° C. at a heating rate of 20 ° C./min.
Therefore, the obtained pitch-based needle coke can be suitably used as an aggregate for graphite electrodes for electric furnace steelmaking. As a method for producing a graphite electrode product using the obtained pitch-based needle coke, a raw material obtained by adding an appropriate amount of binder pitch to needle coke is heated and kneaded, and then the raw electrode obtained by molding is fired to graphitize. After that, there is a method of processing.

Claims (7)

A hydrogenation treatment device for hydrogenating the raw coal tar pitch, a separation device for separating light oil from the hydrogenated coal tar pitch discharged from the hydrogenation treatment device, and hydrogenation of the light oil separated by the separation device. Equipped with a recycling circuit to supply to the processing equipment
The recycling circuit is a circuit that supplies light oil to a plurality of locations in the hydrogenation treatment apparatus.
The hydrogenation treatment apparatus is provided with a plurality of temperature sensors, and has a function of controlling the supply amount of a plurality of circuits for supplying light oil to the hydrogenation treatment apparatus according to the temperature information from the temperature sensors.
A hydrogenated coal tar pitch manufacturing device provided with a cooling device for cooling light oil in the recycling circuit. The apparatus for producing a hydrogenated coal tar pitch according to claim 1, wherein the raw material coal tar pitch is a light oil separated coal tar pitch obtained by separating and removing light oil from the coal tar pitch. The hydrogenated coal tar pitch manufacturing apparatus according to claim 1 or 2 , wherein the cooling device is a heat exchanger. The apparatus for producing a hydrogenated coal tar pitch according to any one of claims 1 to 3 , wherein the hydrogenation treatment apparatus is a continuous fixed bed reactor. The hydrogenated coal tar pitch manufacturing apparatus according to any one of claims 1 to 4 , wherein the separation apparatus is a distillation column or a gas-liquid separator. Claims 1 to 5 have a line for supplying raw material coal tar pitch and hydrogen to the hydrogenation treatment apparatus, and the line for supplying coal tar pitch and a line for supplying hydrogen are previously merged. The apparatus for producing a hydrogenated coal tar pitch according to any one of the above items. The claim that the hydrogenation treatment apparatus has a raw material coal tar pitch supply port and a hydrogen supply port, and at least one hydrogen supply port is provided on the downstream side of the raw material coal tar pitch supply port. The apparatus for producing a hydrogenated coal tar pitch according to any one of 1 to 6 .

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