JP2015183175A - Treatment method of coal tar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method that can easily remove low boiling point components at a low cost by distillation without causing trouble in a distillation apparatus even if coal tar has a high quinoline insoluble content.SOLUTION: A solvent 2 having a lower boiling point than that of coal tar is mixed with raw material coal tar 1, and then the mixture is left at rest to precipitate a quinoline insoluble by a difference in specific gravity. Consequently, the mixture is separated into clear liquid 3, which is a mixture of coal tar and the solvent and contains no quinoline insoluble, and precipitated liquid 6, which is a mixture of coal tar and the solvent and has a content of the quinoline insoluble of 30 mass% or more and 45 mass% or less. The precipitated liquid 6 is continuously supplied to a thin film distillation apparatus 11 to be subjected to vacuum distillation, whereby the solvent is continuously distilled off to obtain a recovered solvent 7, and concentrated pitch 8, which is quinoline insoluble-concentrated coal tar, is continuously discharged.

Description

  The present invention relates to a treatment method for removing low-boiling components from coal tar containing quinoline insoluble matter.

  As a method for removing quinoline insoluble matter in coal tar, a solvent having a boiling point lower than that of coal tar is added to coal tar, and the quinoline insoluble matter is precipitated and separated by a difference in specific gravity to obtain a clarified liquid containing no quinoline insoluble matter. A method is known in which the clarified liquid is distilled to remove the solvent to produce coal tar containing no quinoline insoluble matter. For example, Patent Documents 1 and 2 disclose a method in which an aromatic hydrocarbon solvent or an aliphatic hydrocarbon solvent is added to coal tar at a predetermined ratio to efficiently precipitate and separate quinoline insoluble matter. .

The methods disclosed in Patent Documents 1 and 2 can treat a large amount of coal tar as compared with other separation methods such as filtration and centrifugation, and contain quinoline insolubles in the clarified liquid. Since the rate is low and easy to control, it is used industrially.
In addition, according to the methods disclosed in Patent Documents 1 and 2, a sedimentation solution (lower layer) containing a large amount of quinoline insoluble matter is generated together with the clarified liquid by sedimentation separation, and any of these liquids contains the solvent. It is. Therefore, from the viewpoint of reducing the cost required for the quinoline insoluble content removal treatment, it is general to recover the solvent from the sedimented solution by distillation and reuse it for the quinoline insoluble content removal treatment.

Japanese Patent Laid-Open No. 52-28501 JP-A-52-78201

  The quinoline insoluble matter contained in coal tar is generally considered to be solid matter, and as the content of quinoline insoluble matter in coal tar increases, the solid matter that blocks the piping increases and the viscosity of the sedimented liquid Is increased exponentially, troubles such as clogging are likely to occur in the piping and distillation tower of the distillation apparatus. Therefore, when continuously distilling the sediment using the distillation apparatus, in order to continuously recover the solvent from the sediment and discharge the distillation residue from the distillation apparatus, it is used to remove quinoline insoluble matter. It was necessary to limit the content of the quinoline insoluble content of the coal tar (hereinafter also referred to as “raw coal tar”) to less than about 5 to 10% by mass.

When the above-described quinoline insoluble content removal treatment is performed on the raw material coal tar having a quinoline insoluble content of 10% by mass or more, it is possible to obtain a clarified liquid containing no quinoline insoluble content, Since it becomes difficult to recover the solvent from the sedimented solution by distillation or the recovery rate of the solvent is greatly deteriorated, there is a possibility that the cost required for the removal treatment of the quinoline insoluble matter may increase.
Therefore, the present invention solves the above-mentioned problems of the prior art, and even if it is coal tar having a high content of quinoline insoluble matter, it can be easily and at low cost without causing trouble in the distillation apparatus. An object of the present invention is to provide a treatment method capable of removing low boiling point components by distillation.

In order to solve the above problems, a method for treating coal tar according to one embodiment of the present invention includes a quinoline-insoluble component and a low-boiling component, and the content of the quinoline-insoluble component is 30% by mass or more and 45% by mass or less. The tar is continuously supplied to a thin film distillation apparatus, and the low boiling point component is continuously distilled off from the coal tar.
In this method for treating coal tar, the low boiling point component is a solvent having a boiling point lower than that of the coal tar, and the coal tar is mixed with the raw material coal tar, and the mixture is allowed to stand to change the specific gravity difference. The lower layer sediment containing the quinoline insoluble matter obtained by precipitating the quinoline insoluble matter and separating and removing the upper clarified liquid may be used.

  According to the method for treating coal tar according to the present invention, even if coal tar having a high content of quinoline insolubles is used, it is easy and low-cost without causing trouble in the distillation apparatus. Can be removed.

It is a figure explaining one Embodiment of the processing method of coal tar concerning the present invention.

An embodiment of a method for treating coal tar according to the present invention will be described below in detail with reference to the drawings.
When coal tar containing quinoline-insoluble components and low-boiling components is distilled using a batch-type distillation apparatus equipped with a distillation column, and low-boiling components are distilled from coal tar, quinoline-insoluble components in coal tar When the content of is high, troubles such as blockages are likely to occur in the piping and distillation tower. In order to continuously perform the distillation by continuously supplying coal tar to the distillation apparatus, it is necessary to continuously distill off the low-boiling components and discharge the distillation residue from the distillation apparatus. If the content of quinoline insoluble matter is high, the above trouble may occur, and it may be difficult to continuously distill off the low-boiling components and discharge the distillation residue.

  According to the coal tar treatment method of the present embodiment, since the coal tar is distilled by a thin film distillation apparatus, even if the coal talin insoluble content is 30% by mass or more and 45% by mass or less, The low boiling point component can be distilled off and the distillation residue can be continuously discharged without any trouble. Therefore, coal tar can be continuously supplied to a thin-film distillation apparatus and vacuum distillation can be performed to continuously distill off low-boiling components from coal tar. For example, pitch is produced by continuously supplying coal tar having a high content of quinoline-insoluble matter to a thin-film distillation apparatus and performing distillation under reduced pressure to continuously distill low-boiling components having a boiling point of 400 ° C. or lower. be able to.

The following is an example of recovering a solvent by distillation using a thin film distillation apparatus from coal tar having a quinoline insoluble content of 30% by mass to 45% by mass and containing a solvent, as shown in FIG. The method for treating coal tar according to the present embodiment will be described with reference to FIG.
In order to remove the quinoline insoluble matter in the coal tar (raw material coal tar) 1, the following treatment is performed. Solvent 2 having a boiling point lower than that of coal tar (corresponding to “low-boiling component” which is a constituent requirement of the present invention) corresponds to coal tar 1 (“raw coal tar” which is a constituent requirement of the present invention). The mixture is allowed to stand in the sedimentation tank 9 and the quinoline insoluble matter is allowed to settle due to the difference in specific gravity. Then, the upper clarification liquid 3 which is a mixture of coal tar and a solvent and does not contain quinoline insoluble matter, and a lower layer whose content of quinoline insoluble matter which is a mixture of coal tar and a solvent is 30% by mass or more and 45% by mass or less. Separated into sediment 6.

If the clarified liquid 3 and the sedimented liquid 6 are separated and the clarified liquid 3 is distilled under reduced pressure, for example, by a distillation apparatus 10 to remove the solvent, the coal tar 5 containing no quinoline-insoluble matter is obtained and the recovered solvent 4 is obtained. Coal tar 5 containing no quinoline-insoluble component can be used as a raw material for various products. Since the clarified liquid 3 contains almost no quinoline insoluble matter, a thin-film distillation apparatus can be used as the distillation apparatus 10, and a batch type distillation apparatus equipped with a distillation column can also be used.
Since the content of the quinoline insoluble component is as high as 30% by mass or more and 45% by mass or less, the sediment 6 is distilled using the thin film distillation apparatus 11. Distillation residue 8 which is coal tar in which quinoline insoluble matter is concentrated, while continuously collecting sediment solution 6 to thin-film distillation apparatus 11 and performing, for example, vacuum distillation, continuously distilling off solvent to obtain recovered solvent 7. (Hereinafter also referred to as “concentrated pitch 8”) is continuously discharged. In this way, it is possible to treat the sediment 6 generated when the quinoline insoluble matter is removed from the raw coal tar 1. The concentrated pitch 8 can be used as a raw material for various products.
If the thin film distillation apparatus 11 is used for distillation of the sedimentation liquid 6, even if the content rate of the quinoline insoluble content of the sedimentation liquid 6 is high, distillation can be easily performed without causing the trouble in the distillation apparatus. When a batch type distillation apparatus equipped with a distillation column is used, the content of the quinoline insoluble component of the raw coal tar is limited to less than about 5 to 10% by mass. Raw material coal tar having a content of up to 25% by mass can be processed.

Therefore, conventionally, the raw material coal tar having a quinoline insoluble content of 10% by mass or more and 25% by mass or less has been difficult to industrially remove the quinoline insoluble component. According to this, it is easy to industrially remove the quinoline insoluble matter. Therefore, when manufacturing a product using coal tar as a raw material, the range of selection of coal tar is widened, and low-quality coal tar can be effectively used.
Moreover, the recovered solvents 4 and 7 obtained by distillation can be reused for the process which mixes with the raw material coal tar 1 and removes a quinoline insoluble matter. Therefore, the process which removes the quinoline insoluble content in coal tar can be performed at low cost.
Although the kind of solvent to be used is not particularly limited, a solvent having a boiling point of 300 ° C. or lower is preferable, and specific examples include gasoline, light oil, and kerosene. A solvent may be used individually by 1 type and may use 2 or more types together.

The present invention will be described more specifically with reference to the following examples.
(Reference example)
Kerosene and creosote oil as a solvent are mixed with the raw material coal tar having a quinoline insoluble content (QI content) of 9.4% by mass, and this mixture is allowed to stand in a settling tank and quinoline insoluble due to the difference in specific gravity. Minutes were allowed to settle. Then, it separated into the clear liquid of the upper layer which is a mixture of coal tar and a solvent and does not contain a quinoline insoluble matter, and the lower sedimentary liquid which is a mixture of coal tar and a solvent and contains a quinoline insoluble matter. The content of quinoline insoluble matter in the sedimented liquid was 18.5% by mass.

  Next, the precipitated liquid is continuously supplied to the thin film distillation apparatus and distilled under reduced pressure. The solvent is continuously distilled off from the precipitated liquid, and the concentrated pitch, which is coal tar in which the quinoline insoluble matter is concentrated, is obtained by the thin film distillation apparatus. Discharged continuously. By using a thin film distillation apparatus, it was possible to continuously recover the solvent from the sediment and discharge the concentrated pitch. The content of quinoline insolubles in the concentrated pitch was 27.6% by mass. Further, the recovery rate of the solvent from the sedimented liquid (amount of solvent recovered / amount of solvent in the sedimented liquid) was 98.2% by mass. The results are summarized in Table 1.

Example 1
The sedimentation liquid was treated in the same manner as in the reference example except that the content of the quinoline insoluble content of the raw material coal tar was 17.0% by mass. By using a thin film distillation apparatus, it was possible to continuously recover the solvent from the sediment and discharge the concentrated pitch. The content of quinoline insoluble matter in the sedimented liquid was 33.7% by mass. The results are as shown in Table 1.
(Example 2)
The sedimentation solution was treated in the same manner as in the reference example except that the content of the quinoline insoluble component of the raw material coal tar was 24.7% by mass. By using a thin film distillation apparatus, it was possible to continuously recover the solvent from the sediment and discharge the concentrated pitch. The content of quinoline insoluble matter in the sedimented liquid was 43.2% by mass. The results are as shown in Table 1.

(Comparative Example 1)
Except for using a batch-type distillation apparatus equipped with a distillation column as the distillation apparatus, the sedimentation liquid was treated in the same manner as in the reference example. Since the content of quinoline insolubles in the raw coal tar was low, it was possible to recover the solvent from the sediment and discharge the concentrated pitch without causing problems such as clogging in the piping and distillation column of the distillation equipment. . The results are as shown in Table 1.
(Comparative Example 2)
The sedimentation liquid was treated in the same manner as in Example 1 except that a batch distillation apparatus equipped with a distillation tower was used as the distillation apparatus. Due to the high content of quinoline insolubles in the raw coal tar, clogging of distillation equipment piping and distillation towers occurred. Therefore, the recovery of the solvent from the sedimentation liquid and the discharge of the concentrated pitch cannot be performed continuously, and the quinoline insoluble content in the concentrated pitch and the recovery ratio of the solvent from the sedimentation liquid are accurate. The value could not be calculated.

(Comparative Example 3)
The sedimentation liquid was treated in the same manner as in Example 2 except that a batch distillation apparatus equipped with a distillation tower was used as the distillation apparatus. Due to the high content of quinoline insolubles in the raw coal tar, clogging of distillation equipment piping and distillation towers occurred. Therefore, the recovery of the solvent from the sedimentation liquid and the discharge of the concentrated pitch cannot be performed continuously, and the quinoline insoluble content in the concentrated pitch and the recovery ratio of the solvent from the sedimentation liquid are accurate. The value could not be calculated.

DESCRIPTION OF SYMBOLS 1 Raw material coal tar 2 Solvent 3 Clear liquid 4 Recovery solvent 5 Coal tar which does not contain quinoline insoluble matter 6 Precipitation liquid 7 Recovery solvent 8 Concentration pitch 9 Settling tank 10 Distillation apparatus 11 Thin film distillation apparatus

Claims (2)

  Coal tar containing a quinoline-insoluble component and a low-boiling component and having a content of the quinoline-insoluble component of 30% by mass or more and 45% by mass or less is continuously supplied to a thin-film distillation apparatus. Is a method of treating coal tar, characterized in that the coal tar is distilled off continuously. The low boiling point component is a solvent having a lower boiling point than the coal tar,
The coal tar is obtained by mixing the solvent with the raw material coal tar, allowing the mixture to stand, precipitating the quinoline insoluble matter due to the difference in specific gravity, and separating and removing the upper clarified liquid. The method for treating coal tar according to claim 1, wherein the method is a lower layer sedimentation solution containing the coal tar.

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