JPS60245694A - Treatment of cut tar - Google Patents

Abstract

PURPOSE:To treat cut tar advantageously, by removing a light oil fraction from coal tar, hydrocracking the resulting cut tar, distilling the hydrocracked product to obtain light oils and refining the resulting high-boiling fraction to obtain a binder component having a low sulfur content. CONSTITUTION:Coal tar formed as by-product during dry distillation of coal is distilled to obtain a fraction having a b.p. of 270 deg.C or below. The resulting cut tar is hydrocracked in the presence of a catalyst at 400-500 deg.C under a hydrogen pressure of 100-200kg/cm<2>G. The hydrocracked product is distilled to recover a valuable light oil fraction having a b.p. of 270 deg.C or below and a heavy oil fraction having a b.p. higher than 270 deg.C. A ketone solvent is added to the heavy oil fraction to remove the catalyst and a solvent-insoluble matter contg. sulfur as sludge. The solvent is then removed by distillation, whereby a binder component having a low sulfur content suitable for use as a binder for coke oven coal can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for treating cut tar obtained by distilling coal tar by-produced from a coke oven to remove light oil components.

[Technical background of the invention and its problems] Coal tar produced as a by-product from a coke oven is distilled and separated in the following boiling point ranges in descending order of boiling point.

Tar light oil Boiling point 180°C or lower Carpol oil Boiling point 180-210°C Naphthalene oil Boiling point 210-230°C Absorption oil Boiling point 230-270°C Road tar Boiling point 270'C or higher - Anthracene oil Boiling point 270-350°C Pitch Boiling point 350'
C or higher cut tar is distilled coal tar with a boiling point of 270
It refers to tar from heavy oils from which light oils below °C have been removed, and although it is a distillate that makes up the majority of tar distillation products, demand is low.

Light oil fractions contain many compounds useful as chemical raw materials, such as naphthalene and anthracene, so they are in greater demand than heavy oil fractions and are more expensive, so it is desirable to increase the production of light oils. It is rare. Therefore, various methods have been developed to increase the production of light oil fractions by hydrocracking cut tar.

On the other hand, in recent years, strong caking coal, which is an important raw material for coke for blast furnace charging, is expensive and in short supply, so it is necessary to use steam coal, which has poor fluidity, as much as possible while trying to save on strong caking coal. A method has been developed. This method involves adding a binder to coal, which has poor fluidity, to fluidize the coal, and polymerizing it with the coal to produce strong coke suitable for blast furnace operation.

The properties necessary for this binder are listed below.

(a) Highly aromatic to dissolve coal.

(b) It has a high softening point and does not volatilize during coke production. (c) Contains many compounds that easily react with coal.

The binders currently in use are roughly divided into petroleum-based and coal-based. Petroleum-based binders have low aromaticity because petroleum is originally a mixture of aliphatic compounds, and are less aromatic. It is used after being processed. In addition, coal-based binders are obtained by heat-treating coal tar, and because coal tar has undergone a high-temperature thermal history, its aromaticity has developed too much.
It is difficult to polymerize with coal.

Furthermore, it is known that if hot metal produced in a blast furnace contains sulfur and carbon, high-quality products cannot be obtained. Therefore, there are two methods for reducing the sulfur content in hot metal: (1) reducing the sulfur content in the raw material, and (2) desulfurizing the hot metal, but the desulfurization cost is lower than (2). Method 1) is available, but since method (1) is cheaper and easier to desulfurize, it is desired to use a raw material with a low sulfur content. Therefore, when using a binder, it is natural.

It is also required that the sulfur content contained in the binder be low.

[Objective of the Invention 1 The present invention has been researched and developed in view of the above-mentioned problems, and the purpose of the present invention is to obtain expensive and useful light oil and to remove the heavy oil produced in the process. An object of the present invention is to provide a method for treating cut tar that can produce a component effective as a caking agent that has low sulfur, high caking property, and a low softening point and does not easily react with coal.

[Summary of the Invention J The gist of the present invention to achieve the above object is to hydrocrack cut tar from which light oil components with a boiling point of 270°C or less in coal tar have been removed, and then distill it to obtain a light oil. This is a method for treating cut tar, which is characterized by producing a fraction with a boiling point exceeding 270°C to obtain a component for a binder with a low sulfur content.

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

Since (+) light oil contains many compounds that are promising as chemical raw materials such as naphthalene and anthracene, as mentioned above, there is a desire to obtain light oil from cut tar as much as possible. For this purpose, light oil can be obtained by hydrogenolyzing cut cool and distilling it. However, on the other hand, unless the use of heavy oil obtained through hydrocracking and distillation is sufficiently developed, the cost of carrying out cut tar treatment cannot be absorbed.

(2) Therefore, the present inventors proceeded with the development of uses for the obtained heavy oil and found that it is extremely effective as a caking agent for coal for coke oven charging. The obtained heavy oil satisfies all of the above-mentioned properties as a binder, as shown in the examples below. It has also been found that when an iron-based catalyst is used in the hydrocracking process, the sulfur content in the resulting heavy oil (pitch) is significantly reduced, and in this respect it is also effective as a binder for coal for coke oven charging. Ta.

[Specific examples of the invention j The present invention will be explained in further detail below.

The cut tar in this invention is obtained by distilling high-temperature tar, low-temperature tar, etc. that are produced as a by-product during coal carbonization, and has a boiling point of 270°C.
The following fractions are removed by 1 and used. This is due to consideration of cut tar usage efficiency, hydrogen cracking efficiency, and catalyst efficiency. In other words, it is better to remove the fraction with a boiling point of 270°C or lower in advance, which improves the utilization efficiency, hydrogen cracking efficiency, and catalyst efficiency of cut tar, and is convenient for the subsequent separation of binder products and light oil products. be.

In the present invention, the above-mentioned cut tar is hydrogenolyzed in the presence of a catalyst as shown in FIG. The reaction temperature at this time is 400-500℃, and the hydrogen pressure is 100-200 kg/
Keep crn'G or higher. The reaction temperature is 40
At temperatures below 0°C, the yield of the desired light oil is low, as shown in Figure 2, and at temperatures above 500°C, the lightening reaction and its reverse polymerization reaction proceed rapidly, resulting in a decrease in the yield of light oil. do.

In addition, when the hydrogen pressure is less than 100 kg/cm'G, the hydrogenation reaction of aromatic rings is difficult to proceed, so the decomposition reaction that follows the hydrogenation reaction is difficult to occur, and the yield of the target fraction is reduced. On the other hand, if the hydrogen pressure becomes higher than necessary, the amount of expensive hydrogen consumed increases, which is uneconomical, and the cost required for pressure-resistant equipment becomes relatively high.

Note that the catalyst used for hydrogenolysis is not particularly limited, but an iron-based catalyst that is easy to prepare, inexpensive, and has a desulfurization effect as described later can be used. Examples of iron-based catalysts include red mud and iron ore, and the amount used may be about 1-10% based on cut tar. The reason why the amount of catalyst used is about 1 to 10% is that if the catalyst concentration is less than 1%, there is no effect, and if it is more than 10%, the catalyst efficiency becomes poor.

Iron oxide in the iron-based compound used as a catalyst is effective in desulfurizing organic sulfur-containing compounds, and the desulfurization rate is rapid. This desulfurization reaction using iron oxide is effective not only for thioalcohols but also for sulfur contained in heterocycles. Therefore, it becomes possible to desulfurize compounds such as dibenzothiophene contained in coal tar, which is useful for producing a low-sulfur binder. And, in fact,
After the desulfurization reaction, iron oxide has changed to iron sulfide, and this iron sulfide is effective in hydrogen reactions and hydrocracking reactions, so it is useful for improving light oil yield.

The above hydrocracked product is converted into gas and an expensive and useful light oil fraction with a boiling point of 270°C or less in the next distillation step.
It is separated and recovered from heavy oil with a temperature exceeding 0°C. Further, a ketone solvent such as acetone is added to the heavy oil having a boiling point of over 270° C. to remove the catalyst and the ketone solvent-insoluble components including sulfur content into sludge. The ketone solvent is removed by distillation to obtain refined heavy oil. As a ketone solvent, acetone has a boiling point of 2.
00°C or less is preferable.

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

■During the coal carbonization process, hydrogen is quickly provided to relatively high-molecular radicals generated by the thermal decomposition of coal to stabilize them, resulting in a high content of high-molecular compounds, which facilitates the polymerization reaction during the carbonization process. do.

■Since it is easily thermally decomposed, the radical weight increases during the carbonization process, making it easier to radical polymerize.

■Effective in reducing viscosity and easy to blend into coal.

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

Examples] Further, the present invention will be explained in detail with reference to Examples.

Coal tar produced as a by-product from coke ovens is distilled to a boiling point of 2.
The fraction below 70°C was removed, and the cut tar having the elemental analysis values shown in Table 1 was hydrocracked using a hydrocracker with a processing capacity of 0.5 kg/Hr under the operating conditions shown in Table 2. did.

Table 1 Elemental analysis values of Cut Cool Table 2 Hydrogenolysis conditions Further, the hydrogenolysis product was distilled to produce a gas with a boiling point of 270°C.
It was separated into the following light oil and heavy oil with a boiling point exceeding 270°C. The material balance is shown in Table 3.

Table 3 Next, acetone is added to the hydrocracked heavy oil with a boiling point of over 270°C to remove the acetone-insoluble content by turning it into sludge, and the acetone in the acetone solution is distilled off to remove the acetone-soluble content. I got it. By removing acetone-insoluble components by adding acetone, most of the catalyst and quinoline-soluble components contained in the heavy oil were removed. In addition, a caking test for acetone soluble content was conducted. Table 4 shows its properties along with comparative examples. A comparative example is coal tar pitch obtained by heat treating ordinary coal tar.

Table 4 As is clear from Table 4, the caking property is improved, and 80% of the component effective as a caking agent is contained, and the sulfur content is 0.4%, which is a low sulfur content.

Furthermore, when the properties of the refined heavy oil were analyzed by elemental analysis, nuclear magnetic resonance, etc., it was found that a large amount of hydrogen aromatic ring compounds, which are not contained in conventional coal tar pitch, were present.

[Effects of the Invention] As shown in the following, according to the method of the present invention, as is clear from Examples Table 3 and Table 4, expensive and useful light oil is produced as a by-product, and it also has low sulfur and high caking properties. , it is possible to obtain a component effective as a binder for coal for coke oven charging, which has a low softening point and easily reacts with coal.

[Brief explanation of the drawing]

Figure ff51 is a process diagram according to the present invention, and Figure 2 is a diagram showing the relationship between reaction temperature, light oil yield, and hydrogen gas absorption amount in the cut-cool hydrocracking reaction. Patent applicant: Sumitomo Metal Industries, Ltd. Representative Patent Attorney Yoshihisa Nagai Figure 1 Figure 2 F! Hitoshi Asa (0C)

Claims (1)

[Claims] (1) The cut tar from which the light oil with a boiling point of 270°C or less in coal tar has been removed is hydrocracked and then distilled to obtain a light oil, and the fraction with a boiling point of over 270°C is purified to reduce A method for processing cut tar characterized by obtaining a sulfur-containing binder component.