JPH0699692B2 - Cuttall processing method - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for treating cut tar obtained by distilling coal tar produced as a by-product from a coke oven to remove light oil.

[Technical Background of the Invention and Problems Thereof] Coal tar produced as a by-product from a coke oven is separated by distillation in the boiling range shown below in ascending order of boiling point.

Tar light oil Boiling point 180 ℃ or less Carboru oil Boiling point 180 to 210 ℃ Naphthalene oil Boiling point 210 to 230 ℃ Absorbing oil Boiling point 230 to 270 ℃ Road tar Boiling point 270 ℃ or more Anthracene oil Boiling point 270 to 350 ℃ Pitch boiling point 350 ℃ or more What is cut tar? Distilling coal tar, boiling point 270 ℃
It refers to the heavy oil tar from which the following light oil has been removed, and there is little demand for the fraction that is the majority of tar distillation products.

Since the light oil fraction contains many compounds that are advantageous as chemical raw materials such as naphthalene and anthracene, it is in high demand and expensive compared to the heavy oil fraction, so it is desirable to increase the production of light oil. It is rare. Therefore, various methods for hydrocracking cut tar to increase the production of light oil fractions have been developed.

On the other hand, in recent years, strong coking coal, which is an important raw material for blast furnace charging coke, is expensive and is running out of stock. Therefore, we will use steam coal, which has the least fluidity possible, while saving strong coking coal. The method is being developed. This method is a method of blending a binder with coal having poor fluidity to fluidize the coal and polymerize the coal to produce strong coke suitable for blast furnace operation.

The properties required for this binder are listed below.

(A) High aromaticity for melting coal.

(B) It has a high softening point and does not volatilize during coke production.

(C) Contain many compounds that easily react with coal.

Currently used binders are roughly classified into petroleum-based and coal-based binders. Petroleum-based binders have a low aromaticity because petroleum is originally a mixture of aliphatic compounds, and thus aromatized, etc. Is used after processing. Further, the coal-based binder is obtained by heat treatment of coal tar, and since coal tar has undergone a high temperature heat history, aromaticity has been overdeveloped,
Difficult to polymerize with coal.

Further, it is known that a good quality product cannot be obtained if the hot metal produced in the blast furnace contains a sulfur content. Therefore, there are two methods for reducing the sulfur content in the hot metal: (1) reducing the sulfur content in the raw material, and (2) performing desulfurization of the hot metal, but the desulfurization cost is lower than (2). Since 1) is cheaper and easier, it is desired to use a raw material having a low sulfur content. Therefore, when the binder is used, it is naturally required that the sulfur content in the binder is low.

[Object of the Invention] The present invention has been researched and developed in view of the above-described matters, and an object of the present invention is to obtain an expensive and advantageous light oil and to extract heavy oil from the heavy oil produced in the process. It is intended to provide a method for treating cut tar, which can produce an ingredient effective as a binder having low sulfur, high caking property, and low softening point and easily reacting with coal.

[Summary of the Invention] The gist of the present invention for achieving the above object is to hydrocrack cut tar in which light oil having a boiling point of 270 ° C or less in coal tar is removed, and then distilled to obtain light oil,
This is a method for treating cut tar, characterized in that all fractions having a boiling point of higher than 270 ° C. are purified by using acetone to obtain a binder having a low sulfur content.

Therefore, in the present invention, as described in the section of the boiling point range, pitch having a boiling point of 350 ° C. or higher is also used as the binder component.

That is, the present invention is based on the following.

(1) Since the light oil content contains many promising compounds as chemical raw materials such as naphthalene and anthracene, there has been a demand to obtain the light oil content from Kattar as much as possible as described above. For that purpose, light oil can be obtained by hydrocracking cut tar and distilling. But,
On the other hand, if the application of the heavy oil obtained through hydrocracking and distillation is not sufficiently developed, the cost of performing the cut tar treatment cannot be absorbed.

(2) Then, the inventors of the present invention have advanced the application development of the heavy oil obtained, and found that it is extremely effective as a binder for the coal for charging the coke oven. The obtained heavy oil content satisfies all the above-mentioned properties as a binder, as will be shown in Examples below. It was also found that when an iron-based catalyst is used in the hydrocracking process, the sulfur content in the obtained heavy oil (pitch) is extremely low, and in this respect it is also effective as a binder for coal for charging coke ovens. It was

Specific Examples of the Invention The present invention will be described in more detail below.

The cut tar used in the present invention is obtained by distilling high-temperature tar, low-temperature tar, and the like, which are by-produced during coal carbonization, to remove a fraction having a boiling point of 270 ° C. or lower. This is because the utilization efficiency of the cut tar, the hydrogenolysis efficiency and the catalyst efficiency were taken into consideration. That is, it is better to remove the fraction having a boiling point of 270 ° C. or lower in advance, because the utilization efficiency of the cut tar, the hydrogenolysis efficiency and the catalyst efficiency are good, and it is convenient for the subsequent separation of the binder product and the light oil product. .

In the present invention, the above-mentioned cut tar is hydrocracked in the presence of a catalyst as shown in FIG. The reaction temperature at this time is 400 to 500 ° C., and the hydrogen pressure is 100 to 200 kg / cm ² G, or higher. When the reaction temperature is lower than 400 ° C, the yield of the target light oil is low as shown in Fig. 2, and at the temperature of 500 ° C or higher, the lightening reaction and the reverse polymerization reaction proceed rapidly, so the light oil yield is low. The rate drops. Also, hydrogen pressure is 100k
If it is less than g / cm ² G, the hydrogenation reaction of the aromatic ring is difficult to proceed, so that the decomposition reaction that follows the hydrogenation reaction is unlikely to occur and the yield of the target fraction is reduced, while the hydrogen pressure is If it is higher than necessary, the consumption of expensive water increases, which is uneconomical, and the cost required for pressure resistant equipment becomes expensive.

The catalyst used for hydrocracking is not particularly limited, but an iron-based catalyst that is easy to take in and inexpensive and has a desulfurizing effect as described later can be used. Examples of the iron-based catalyst include red mud and iron ore, and the amount thereof used may be about 1 to 10% based on the cut tar. The amount of the catalyst used is set to about 1 to 10% because if the catalyst concentration is less than 1%, there is no effect, and if it is 10% or more, the catalyst efficiency deteriorates.

The iron oxide in the iron-based compound used as the catalyst is effective for desulfurization of the organic sulfur-containing compound, and the desulfurization rate is also rapid. This desulfurization reaction with iron oxide is effective not only for thioalcohol but also for sulfur contained in the heterocycle. Therefore, compounds such as dibenzothiophone contained in coal tar can be desulfurized, which is useful for the production of low-sulfur binders. And, in fact,
The iron oxide after the desulfurization reaction has changed to iron sulfide, and this iron sulfide is effective for the hydrogenation reaction and the hydrocracking reaction, and therefore helps to improve the yield of light oil.

In the next distillation step, the above hydrocracking products are separated and recovered into a gas, an expensive and useful light oil fraction having a boiling point of 270 ° C or lower and a heavy oil having a boiling point of 270 ° C or higher. Further, a ketan solvent such as acetone is added to the heavy oil component having a boiling point of more than 270 ° C. to remove sludge from the insoluble component of the ketone solvent containing the catalyst and the sulfur component. The ketone solvent is distilled off to obtain a refined heavy oil. Acetone having a boiling point of 200 ° C. or lower is preferable as the ketone solvent.

The refined heavy oil has a sulfur content of 0.5% or less and a large amount of hydrogenated aromatic ring compounds, and the hydrogenated aromatic ring compounds have the following properties.

Hydrogen is rapidly supplied to and stabilized in the relatively high-molecular radicals generated by thermal decomposition of coal during the coal carbonization process, so that a large amount of polymer compounds are included, and the polymerization reaction easily proceeds during the carbonization process. .

Since it is easily decomposed by heat, the radical concentration is increased during the carbonization process, which facilitates radical polymerization.

It is effective in reducing viscosity and becomes easy to mix with coal.

Therefore, the refined heavy oil having such excellent properties can be suitably used as a binder for the coal for charging the coke oven.

[Examples] The present invention will be described in more detail with reference to Examples.

Coal tar produced as a by-product from the coke oven is distilled to a boiling point of 27
Fractions below 0 ° C. were removed, and cut tar having the elemental analysis values shown in Table 1 was hydrocracked under the operating conditions shown in Table 2 by a hydrocracker having a treatment capacity of 0.5 kg / Hr.

Further, the hydrocracking product was distilled and separated into gas, light oil having a boiling point of 270 ° C or lower and heavy oil having a boiling point of 270 ° C or higher.
The material balance is shown in Table 3.

Next, acetone is added to the hydrocracked heavy oil having a boiling point of more than 270 ° C to remove the acetone insoluble matter as sludge,
Acetone in the acetone solution was distilled off to obtain an acetone-soluble matter. By removing the acetone-insoluble matter by adding this acetone, most of the catalyst and quinoline-insoluble matter contained in the heavy oil were removed. Further, a caking property test of the acetone-soluble content was carried out. Table 4 shows the properties together with a comparative example. The comparative example is a coal tar pitch obtained by heat treating ordinary coal tar.

As is clear from Table 4, the caking property is improved and 80% of the components effective as a caking agent are contained, and the sulfur content is
It has a low sulfur content of 0.4%. When the properties of the refined heavy oil were analyzed by elemental analysis, nuclear magnetic resonance and the like, a large amount of hydrogen aromatic ring compounds not contained in conventional coal tar pitch were found.

[Effects of the Invention] As described above, according to the method of the present invention, as is clear from Tables 3 and 4 of the Examples, expensive and useful light oil is produced as a by-product, and low sulfur and high caking properties are obtained. , It is possible to obtain an effective component as a binder for the coal for charging into the coke oven, which has a low softening point and easily reacts with the coal.

[Brief description of drawings]

FIG. 1 is a process diagram according to the present invention, and FIG. 2 is a diagram showing the relationship between the reaction temperature, the light oil yield, and the hydrogen gas absorption amount in the Cattar hydrocracking reaction.

Claims (1)

[Claims] 1. A cut tar from which light oil having a boiling point of 270 ° C. or less in coal tar is removed is hydrolyzed and then distilled to obtain a light oil, and all fractions having a boiling point of 270 ° C. or higher are used with acetone. A method for treating cut tar, which comprises refining and refining to obtain a binder having a low sulfur content.