JP2018127611A - Method for manufacturing coal tar pitch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a coal tar pitch having a high softening point and a high β-resin content.SOLUTION: A method for manufacturing a coal tar pitch having a softening point of 120-140°C and a β-resin content of 20 mass% or more of the present invention comprises: a distillation step for distilling a coal tar and obtaining an intermediate pitch; and a thermally modification step for thermally modifying the intermediate pitch obtained by the distillation step whose temperature lies in a range of 360-380°C while water vapor is blown in the intermediate pitch, where a weight ratio of steam/pitch is in a range of 40-150 kg (steam)/t (pitch).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing coal tar pitch.

  Conventionally, coal tar pitch has been used as a binder for refractory materials such as casting materials for steel refractories, repair materials for steel refractories, graphite crucibles for melting metals, granulated activated carbon, special carbon fibers, graphite electrodes and other special carbon materials. It is used.

  For example, when a refractory is produced using coal tar pitch as a binder, the aggregate and raw materials such as coal tar pitch are mixed and then fired. For this reason, the binder may be required to have an appropriate fluidity and a softening point higher than the boiling point of water so that cracking of the refractory does not occur when water evaporates during firing.

  Further, when a special carbon material such as a graphite electrode is manufactured using coal tar pitch as a binder, graphite (aggregate) and coal tar pitch are combined and molded, and then fired and graphitized. Therefore, the coal tar pitch may be required to have a high β resin content in order to improve the compatibility with graphite (aggregate).

  In Patent Document 1, the first heat treatment is performed within a temperature range of 300 ° C. or more and 400 ° C. or less after performing the first stage heat treatment for 10 hours or less at a predetermined temperature within a temperature range of 300 ° C. or more and 400 ° C. or less. A technique for producing a binder pitch having a high β component concentration by performing the second stage heat treatment within 10 hours at a temperature different from the stage temperature is disclosed.

JP-A-8-218078

  An object of the present invention is to provide a method for producing a coal tar pitch having a high softening point and a high β resin content.

The present invention has the following aspects.
Distillation step of coal tar to obtain an intermediate pitch, and the intermediate pitch obtained in the distillation step within a temperature range of 360 to 380 ° C., water vapor is 40 to 150 kg. In the range of steam / t · pitch, a thermal reforming step of obtaining a coal tar pitch by thermal reforming while blowing into the intermediate pitch, having a softening point of 120 to 140 ° C. and having a β resin content The manufacturing method of coal tar pitch which is 20 mass% or more.

According to the present invention, it is possible to provide a method for producing a coal tar pitch having a high softening point and a high β resin content.
Since the coal tar pitch by the production method of the present invention has a softening point sufficiently higher than the boiling point of water, it can maintain its shape without being softened when water evaporates in the firing step, and cracks in the molded product due to water evaporation. Can be prevented. In addition, the coal tar pitch produced by the production method of the present invention has a high β resin content and excellent compatibility with aggregate coke. Therefore, the coal tar pitch according to the present invention is suitable as a binder for refractories and special carbon materials.

FIG. 1 is an explanatory view for explaining an embodiment of a method for producing a coal tar pitch of the present invention.

  Hereinafter, an embodiment of a method for producing a coal tar pitch of the present invention will be described with reference to FIG. However, the present invention is not limited to the following embodiments.

  FIG. 1 is an explanatory view for explaining an embodiment of a method for producing a coal tar pitch of the present invention. The method for producing coal tar pitch of the present invention includes a distillation step for distilling coal tar to obtain an intermediate pitch, and the intermediate pitch obtained in the distillation step within a temperature range of 360 to 380 ° C. And a thermal reforming step of obtaining a coal tar pitch by thermal reforming while blowing into the intermediate pitch within a range of 40 to 150 kg · steam / t · pitch in an amount / pitch weight ratio.

<Distillation process>
In the distillation process, coal tar as a raw material is charged into a dehydrating tower and dehydrated, and then charged into a fractionating tower and distilled to distill low-boiling oil (naphthalene oil, anthracene oil, etc.). Get an intermediate pitch.
The intermediate pitch is obtained as a residue (residue) after distilling off the low-boiling oil, and the softening point is preferably 70 to 90 ° C.
Moreover, as coal tar used as a raw material, it is preferable to use a component in which components are adjusted in a prior coal tar blending step so that the quinoline insoluble content is adjusted to 4.5 to 15% by mass.

  Moreover, it is preferable to perform the said distillation process by a continuous process (continuous distillation). In the embodiment shown in FIG. 1, an example is shown in which a dehydration tower and a fractionation tower are arranged in series, and both the dehydration treatment and the distillation treatment are performed in a continuous process. In the embodiment shown in FIG. 1, coal tar as a raw material is continuously charged into a dehydration tower, dehydrated continuously in the dehydration tower, and then continuously discharged from the dehydration tower. The discharged coal tar is continuously charged into a fractionation tower by a piping line, continuously distilled in the fractionation tower to obtain an intermediate pitch, and continuously discharged from the fractionation tower. It is comprised so that.

<Thermal reforming process>
In the thermal reforming step, the intermediate pitch obtained in the distillation step is charged into a reforming tank to perform thermal reforming.
In this thermal reforming step, the steam is blown at a steam volume / pitch weight ratio (weight (kg) of steam blown per unit weight (t) of pitch) of 40 while the intermediate pitch is set to a temperature range of 360 to 380 ° C. In the range of ˜150 kg · steam / t · pitch, the coal tar pitch is obtained by thermal reforming while blowing into the intermediate pitch.

  In the present invention, the temperature of the intermediate pitch is within the above range, and heat reforming is performed while blowing water vapor into the intermediate pitch within the above range, so that a softening point of 120 to 140 ° C. and a β resin of 20% by mass or more are obtained. A coal tar pitch having a content can be obtained.

  If the temperature of the intermediate pitch in the thermal reforming step is less than 360 ° C., the intermediate pitch is not sufficiently increased in weight, and a coal tar pitch having a desired softening point and β resin content cannot be obtained. In addition, the time required for the thermal reforming becomes longer and the production efficiency is lowered. On the other hand, if the temperature of the intermediate pitch in the heat reforming step is higher than 380 ° C., the mesophase which is a quinoline insoluble component increases, and a coal tar pitch having a desired β-resin content cannot be obtained. Further, the coal tar pitch becomes too heavy, or a part of the coal tar pitch is thermally decomposed, making it difficult to obtain a coal tar pitch having a desired softening point.

In addition, if the amount of steam blown in the thermal reforming process is less than 40 kg · steam / t · pitch, the light component cannot be sufficiently distilled, and the coal tar pitch has a low softening point and has a desired softening point. Tar pitch cannot be obtained. On the other hand, if the amount of steam blown in the thermal reforming step is more than 150 kg · steam / t · pitch, the coal tar pitch has a too high softening point and a coal tar pitch having a desired softening point cannot be obtained.
The amount of steam blown in the thermal reforming step is preferably 40 to 120 kg · steam / t · pitch, and more preferably 50 to 100 kg · steam / t · pitch in terms of the steam amount / pitch weight ratio.
The steam used in the thermal reforming process is not particularly limited, and examples thereof include saturated steam that can be used in a factory.

  The heat reforming time is preferably 8 to 16 hours. If the heat reforming time is less than 8 hours, the intermediate pitch is not sufficiently heavier and a coal tar pitch having a desired softening point and β resin content may not be obtained. On the other hand, if the heat reforming time exceeds 16 hours, the mesophase, which is insoluble in quinoline, increases, and a coal tar pitch having a desired β-resin content may not be obtained. Further, the coal tar pitch becomes too heavy, or a part of the coal tar pitch is thermally decomposed, making it difficult to obtain a coal tar pitch having a desired softening point.

The thermal reforming in the thermal reforming step is preferably performed by a continuous process (continuous thermal reforming). Further, the thermal reforming is preferably performed using a plurality of reforming tanks. In the embodiment shown in FIG. 1, an example in which two reforming tanks (reforming tank 1 and reforming tank 2) are arranged in series and thermal reforming is performed by a continuous process is illustrated. In the embodiment shown in FIG. 1, the intermediate pitch discharged from the fractionation tower in the distillation step is continuously charged into the reforming tank 1 and thermally reformed in the reforming tank 1, and then the reforming tank. 1 is continuously discharged. The intermediate pitch discharged from the reforming tank 1 is continuously charged into the reforming tank 2 through a piping line, and is thermally reformed in the reforming tank 2 to be a coal tar pitch. 2 is configured to be continuously discharged. At this time, the thermal reforming in the reforming tank 1 and the reforming tank 2 is performed within the temperature range of the predetermined intermediate pitch, and the steam in the reforming tank 1 and the reforming tank 2 is changed. The total amount of blowing is performed under conditions within the range of the predetermined amount of blowing water vapor. The thermal reforming time is the sum of the thermal reforming time in the reforming tank 1 and the thermal reforming time in the reforming tank 2 (the residence time in the reforming tank 1 and the reforming tank 2). In total, 8 to 16 hours are preferable.
By performing the thermal reforming in the thermal reforming process in a continuous process, the thermal reforming efficiency can be increased, and the coal tar pitch production efficiency can be increased. Furthermore, by performing the thermal reforming in a continuous process using a plurality of reforming tanks, the production efficiency of coal tar pitch can be further increased.

The conditions for thermal reforming in the reforming tank 1 and the reforming tank 2 (intermediate pitch temperature, steam blowing amount, thermal reforming time) may be the same or different. As an example, the conditions for the thermal reforming are as follows. In the reforming tank 1, the temperature of the intermediate pitch is in the range of 372 to 376 ° C., the amount of steam blown is in the range of 30 to 45 kg · steam / t · pitch, 5 After performing the thermal reforming for ˜6 hours, in the reforming tank 2, the temperature of the intermediate pitch is in the range of 372 to 376 ° C., and the amount of steam blown is in the range of 30 to 45 kg · steam / t · pitch, Examples include thermal reforming conditions for performing thermal reforming for 5 to 6 hours. The amount of steam blown in the case of performing thermal reforming in a continuous manner using a plurality of reforming tanks is the total amount of steam blown in each reforming tank.
In addition, in embodiment shown in FIG. 1, although the example which has arrange | positioned two reforming tanks and performed thermal reforming is shown, it is not limited to this, The reforming tank used by the thermal reforming process of this invention The number of is arbitrary.

Furthermore, in the present invention, it is preferable that the distillation step and the thermal reforming step are performed in a continuous process. In the embodiment shown in FIG. 1, an example in which a fractionation tower in a distillation step and a reforming tank 1 in a thermal reforming step are arranged in series, and the distillation step and the thermal reforming step are performed in a continuous process. Show. In the embodiment shown in FIG. 1, the intermediate pitch continuously discharged from the fractionation tower is continuously charged into the reforming tank 1 through a piping line and subjected to predetermined thermal reforming. Has been.
By producing coal tar pitch by such a continuous process, the production efficiency of coal tar pitch can be further increased.

  Through the above steps, the coal tar pitch of the present invention is produced. The produced coal tar pitch may be appropriately cooled and solidified using an apparatus such as a cooler.

(Coal tar pitch)
Through the above steps, a coal tar pitch having a softening point of 120 to 140 ° C. and a β resin content of 20% by mass or more is produced.
The upper limit of the β resin content of the coal tar pitch is not particularly limited, but is preferably 30% by mass or less.
Since the coal tar pitch according to the present invention has a softening point sufficiently higher than the boiling point of water, the shape can be maintained without being softened when water evaporates in the baking process, and cracking of the molded body due to water evaporation can be prevented. it can. Further, the β resin content is large and the compatibility with the aggregate coke is also excellent. Therefore, it is suitable as a binder for refractories and special carbon materials.

In addition, the measurement conditions of the softening point and β resin content in the present invention are as follows.
[Measurement conditions for softening point]
The softening point is JIS K 2425: 2006 (creosote oil, processed tar and tar pitch test method). The tar pitch was measured according to the softening point measurement method (ring ball method).
[Measurement conditions for β resin content]
The difference (TI-QI) between the toluene insoluble content (TI) content (% by mass) and the quinoline insoluble content (QI) content (% by mass) was determined, and this was defined as the β resin content (% by mass).
Toluene insoluble content (TI) content is measured according to JIS K 2425: 2006 (Creosote oil, processed tar and tar pitch test method) 14.2 (Toluene insoluble content determination method of processed tar and tar pitch). did.
The quinoline insoluble content (QI) content was measured in accordance with 15.1 (filtration method) of JIS K 2425: 2006 (creosote oil, processed tar and tar pitch test method).

Example 1
According to the embodiment shown in FIG. 1, a coal tar pitch was produced.
<Coal tar blending process>
Coal tar generated when coal was carbonized was blended to obtain raw material coal tar having a quinoline insoluble content adjusted to 7.0% by mass.
<Distillation process>
The raw coal tar was subjected to dehydration treatment and distillation treatment by a continuous process to obtain an intermediate pitch having a softening point of 85 ° C.
<Thermal reforming process>
The intermediate pitch obtained in the distillation step was processed by continuous thermal reforming. That is, the intermediate pitch is continuously charged into the reforming tank 1 and subjected to thermal reforming at an intermediate pitch temperature of 372 ° C. and a steam blowing amount of 45 kg · steam / t · pitch. The intermediate pitch thermally modified in the tank 1 is continuously charged into the reforming tank 2 through a piping line, and the temperature of the intermediate pitch is 372 ° C. and the steam blowing amount is 45 kg · steam / t · pitch. Coal tar pitch was manufactured with quality. The total thermal reforming time in the reforming tank 1 and the reforming tank 2 was 11 hours.
Thereafter, the obtained coal tar pitch was charged into a cooler and solidified by water cooling to obtain a rod-like pitch. Table 1 shows production conditions, properties of coal tar pitch (product), and production efficiency.

(Examples 2 and 3)
A coal tar pitch was produced in the same manner as in Example 1 except that the conditions in the raw material coal tar and the thermal reforming step were changed as shown in Table 1. Table 1 shows production conditions, properties of coal tar pitch (product), and production efficiency.

Example 4
A coal tar pitch was produced in the same manner as in Example 1 except that the thermal reforming in the thermal reforming step was performed in a batch mode (batch mode).
That is, in the same manner as in Example 1, the coal tar blending step and the distillation step were performed to obtain an intermediate pitch having a softening point of 85 ° C. And the said intermediate pitch was charged into the reforming tank, and the thermal reforming in the said reforming tank was performed by the batch type (batch type). As the conditions for the thermal reforming, the temperature of the intermediate pitch was 372 ° C., the steam blowing amount was 90 kg · steam / t · pitch, and the thermal reforming was performed for 11 hours. In addition, it took a total of 4 hours to put the intermediate pitch into the reforming tank, raise the temperature, cool after completion of thermal reforming, and pay it out to the tank outside the reforming tank. Table 1 shows production conditions, properties of coal tar pitch (product), and production efficiency.

(Comparative Example 1)
The intermediate pitch obtained by the same coal tar blending step and distillation step as in Example 1 (however, the distillate component was adjusted and the softening point was adjusted to 135 ° C. in the distillation step) was compared with that of Comparative Example 1. Coal tar pitch was used. That is, in Comparative Example 1, no thermal reforming process was performed. Table 1 shows the properties of the coal tar pitch (product).

(Comparative Example 2)
The raw material coal tar that has undergone the same coal tar blending step as in Example 1 is subjected to dehydration treatment and distillation treatment by a continuous process to obtain an intermediate pitch with a softening point of 70 ° C. Continuously charged, the intermediate pitch temperature is 360 ° C., the steam blowing amount is 15 kg · steam / t · pitch, and then the intermediate pitch is thermally reformed in the reforming tank 1. The reforming tank 2 was continuously charged through a piping line, and the temperature of the intermediate pitch was 360 ° C., and the steam was blown into 22 kg · steam / t · pitch for thermal reforming to produce coal tar pitch. The total thermal reforming time in the reforming tank 1 and the reforming tank 2 was 10 hours. Table 1 shows production conditions, properties of coal tar pitch (product), and production efficiency.

As shown in Table 1, the coal tar pitches of Examples 1 to 4 manufactured by the manufacturing method of the present invention have a desired softening point and β resin content. Since the coal tar pitch of Examples 1 to 4 has a softening point sufficiently higher than the boiling point of water, the shape can be maintained without being softened when water evaporates in the firing step, and cracks of the molded body due to water evaporation can be maintained. Can be prevented. Further, the β resin content is large and the compatibility with the aggregate coke is also excellent.
Furthermore, in Examples 1 to 3, by making the thermal reforming a continuous process, it was possible to further improve the coal tar pitch production efficiency compared to Example 4 in which the thermal reforming was a batch type. .
On the other hand, in Comparative Example 1 in which the thermal reforming of the present invention was not performed, the β resin content could not be sufficiently increased, and a coal tar pitch having a desired β resin content could not be produced. In Comparative Example 2, a coal tar pitch having a desired softening point could not be produced because the amount of steam blown in the thermal reforming process was small.

Claims (1)

A distillation step of distilling coal tar to obtain an intermediate pitch;
While the intermediate pitch obtained in the distillation step is set to a temperature range of 360 to 380 ° C., water vapor is blown into the intermediate pitch at a steam amount / pitch weight ratio of 40 to 150 kg · steam / t · pitch. A thermal reforming step of obtaining a coal tar pitch by thermal reforming,
A method for producing coal tar pitch, which has a softening point of 120 to 140 ° C. and a β resin content of 20% by mass or more.

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