JPH0681835B2 - Liquefaction method of coal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is directed to the fractionation of liquefied oil produced during the liquefaction of coal and separation of normal paraffin in the boiling point of 200 to 350 ° C. TECHNICAL FIELD The present invention relates to stable operation of a liquefaction process and a liquefaction method of coal for producing a high-quality, high-yield liquefied oil product.

(Prior Art) In a coal liquefaction method, ordinary coal and a solvent containing medium and heavy oil produced from coal as a main component are heated together with a catalyst under hydrogen pressure. At that time, as a coal liquefaction solvent, the following ~
Is needed.

In order to dissolve highly aromatic coal, a highly aromatic solvent is required.

A solvent having a high hydrogen donating property is required to suppress recrystallization or polymerization of coal, which is easily decomposed by heat, and increase the liquid yield.

In order to accelerate the thermal decomposition of coal and increase the liquid yield,
A slightly polar solvent is required.

By the way, coal contains normal paraffin, which is thought to be derived from the wax component of the root plant, and it is difficult to decompose when medium / heavy oil in liquefied oil is reused as a liquefaction solvent. Regular paraffin gradually thickens.
When the normal paraffin is concentrated in the circulating solvent, all of the properties required for coal liquefaction solvent are lost.

That is, as for, the regular paraffin is an aliphatic compound and has a weak ability to dissolve coal.

As for the hydrogen donating property, the bond dissociation energy of carbon-hydrogen bond is mentioned, and the bond dissociation energy of a hydrogen donating solvent is usually about 82 Kcal / mol, but for normal paraffin it is about 90 Kcal / mol. There is a difference of 10 Kcal / mol, and normal paraffin has a property that it is difficult to donate hydrogen. The hydrogen donating property is gradually deteriorated due to the concentration of the regular paraffin in the solvent. Furthermore, since the normal paraffin itself is also thermally decomposed, the hydrogen-donating solvent is consumed by the normal paraffin, and the hydrogen-donating property of the solvent is further reduced.

With respect to, normal paraffin is non-polar, and accelerated thermal decomposition cannot be expected.

Therefore, reducing or removing normal paraffins from coal liquefaction solvents is an important requirement. Therefore, the inventors of the present invention previously disclosed JP-A-61-73794 and JP-A-61-101591.
In No. 5, a method of using a paraffin-rich component as a part of a liquefaction solvent after removing a paraffin-rich component from a component having a boiling point of 350 to 450 ° C was provided.

(Technical problem to be solved) However, the melting point of regular paraffin having a boiling point of 350 ° C. or higher is 41 ° C. for heneicosane having a boiling point of 357 ° C., and it is a solid at room temperature. Further, the liquefied oil fraction having a boiling point of 350 ° C. or higher is also a semi-solid, and it is not easy to separate the solid fraction from the semi-solid fraction, and the above method has a problem in this respect. In the above method, a method is used in which normal paraffin is separated after heating or diluting with a fraction having a boiling point of 350 ° C. or lower to form a liquid.

On the other hand, regular paraffin has characteristics such as low odor, low toxicity, low viscosity, poor reactivity, and easy decomposition by microorganisms. Due to this characteristic, the normal paraffin is widely used as it is in various solvents, lubricants, etc., and is also used as a raw material for various surfactants. That is,
Normal paraffins with a boiling point of 350 ° C or higher are used as lubricants and paper processing agents, and normal paraffins with a boiling point of 350 ° C or lower are used as a raw material for solvents and surfactants. In the future, soft detergents or higher alcohols will be used. As a detergent raw material
Increased usage is expected.

Further, the normal paraffin is a clean fuel having a large calorific value, and it is desired that a large amount of the normal paraffin be contained in the liquefied oil product (particularly, naphtha fraction).

(Object of the Invention) The present invention has been made in view of the above circumstances, and not only prevents the reduction of the liquefied oil yield by separating the normal paraffin that inhibits the liquefaction of coal by a simple operation from the medium oil, but also the product. It provides high-value liquefied oil and regular paraffin.

(Structure of the invention) The gist of the present invention is to fractionate coal liquefied oil, and especially to have a boiling point of 200 to 3
After removing the normal paraffin from the 50 ° C component (medium oil), it is mixed with a boiling point of 350 to 540 ° C component (heavy oil), and this mixture is used as a solvent for circulation after hydrogenation treatment. First
The figure is a flow sheet of the present invention. The present invention will be described with reference to the drawings. A slurry in which coal, a solvent, and a catalyst are mixed performs a liquefaction reaction of coal in a liquefaction process. The product after the reaction is fractionally distilled in a distillation process into light oil (boiling point 200 ° C or lower), medium oil (boiling point 200 to 350 ° C) and heavy oil (boiling point 350 to 540 ° C). Of these components, the medium oil is used as a liquefaction solvent after being mixed with heavy oil after separating the normal paraffin. If necessary, the medium oil and the heavy oil may be used by appropriately mixing the whole amount or a part thereof.

The liquefaction conditions in the liquefaction process are reaction temperature 430 to 470.
Desirably, the reaction temperature is 0.5 to 2.0 hours, and the hydrogen pressure is 100 to 200 kg / cm ² .

As shown in Fig. 2, when the reaction temperature is lower than 430 ° C, the target liquefied oil yield for coal liquefaction is low.
The production amount of gas and residue increases, the liquefied oil yield decreases, and operating troubles due to coking increase.

When the hydrogen pressure is less than 100 kg / cm ² , the hydrogenation reaction of the aromatic ring is unlikely to occur, the decomposition reaction subsequent to the hydrogenation reaction is less likely to occur, and the liquid yield is reduced. On the other hand, if the hydrogen pressure becomes higher than necessary, the amount of expensive hydrogen consumed will increase and the cost required to manufacture pressure resistant equipment will become relatively high.

The catalyst for coal liquefaction is not particularly limited, and an iron-based compound that is easily available and inexpensive can be used. Examples of iron-based catalysts include red mud, iron ore, iron mill waste such as converter dust, and waste from the coal gasification process, and the amount used may be 1 to 5% by weight with respect to coal. . Further, it is desirable to use a sulfur compound as a co-catalyst in an amount of 1 to 5% by weight based on coal, similar to the iron catalyst. If the catalyst concentration is less than 1%, there is almost no effect of improving the liquid yield by the iron-based catalyst, and if it exceeds 5%, the catalyst efficiency deteriorates.

The obtained liquefied product is separated by atmospheric distillation or vacuum distillation into a light oil fraction with a boiling point of up to 200 ° C, a medium oil fraction with a boiling point of 200-350 ° C, and a heavy oil fraction with a boiling point of 350-540 ° C. To be done.
Since this middle oil fraction is a liquid, it does not need to be heated and is sent to the normal paraffin separation step as it is. The method for separating the regular paraffin is not particularly limited. Separated into normal paraffins and aromatic compound-rich components by molecular sieve, urea addition method, solvent extraction method and the like. The regular paraffin and the above-mentioned light oil fraction are taken out of the system as products.

The boiling temperature of the medium oil sent to the separation step of the normal paraffin is preferably 200 to 350 ° C. It is better to take light oil with a boiling point of less than 200 ° C as it is out of the system as it is, to improve the efficiency of separating normal paraffin, and to secure a solvent for liquefaction and to lighten liquefied products. As described above, a fraction having a boiling point of 350 ° C. or more is a semi-solid and needs to be heated in order to be treated as a liquid. Therefore, the operation for separating the regular paraffin becomes expensive. Furthermore, when normal paraffin is separated from liquefied oil containing a fraction with a boiling point of 350 ° C or higher, it may be possible to dilute it with a fraction with a boiling point of 350 ° C or lower. In addition, it is necessary to separate the normal paraffin having a boiling point of 350 ° C or less and high product value and the normal paraffin having a boiling point of 350 ° C or more again. Therefore, the boiling point is 350 ° C
It is most desirable to separate normal paraffins from the following medium oils.

Furthermore, according to the experiments conducted by the present inventors, liquefaction conditions (450
The decomposition reaction of normal paraffin at 1 ° C for 1 hour
The average decomposition rate was about 50% for normal paraffins above 350 ℃, and about 20% for normal paraffins with a boiling point below 350 ℃. Therefore, it is considered that the normal paraffin that is concentrated in the solvent under the liquefaction condition is the normal paraffin having a boiling point of 350 ° C or less, and the efficient removal of the normal paraffin outside the reaction system prevents the normal paraffin from inhibiting the liquefaction reaction. I found that it can be prevented.

The medium oil from which the normal paraffin has been removed is mixed with the heavy oil and sent to the solvent hydrogenation step. In the solvent hydrogenation step, for example, Ni-Mo
Hydrogen is 0.5 to 2.0 per solvent due to hydrogenation catalyst such as / Al ₂ O _3.
Wt% is added.

If it is less than 0.5%, the effect of improving the hydrogen donating ability of the solvent is not recognized, and if it exceeds 2%, the amount of expensive hydrogen consumed is large and excessive hydrogenation impairs the hydrogen donating ability.

Hydrogenation conditions include a reaction temperature of 300 to 400 ° C and a reaction time of 0.5.
A hydrogen pressure of 100 to 200 Kg / cm ² is desirable for up to 2.0 hours. If the reaction temperature is lower than 300 ° C., the hydrogenation of the solvent is not sufficiently carried out, and if the reaction temperature exceeds 400 ° C., the decomposition reaction of the solvent is likely to proceed, and the dehydrogenation reaction occurs simultaneously.

Further, if the reaction time is less than 0.5 hours, sufficient hydrogenation reaction is not performed, and if the reaction time exceeds 2 hours, excessive hydrogenation impairs the hydrogen donating property of the solvent. Furthermore, hydrogen pressure
If it is less than 100 kg / cm ² , sufficient hydrogenation cannot be performed, and 200 kg / cm ²
Above this, the cost required for the high-pressure container will be high. The medium / heavy oil that has undergone this hydrogenation step is circulated again as a liquefaction solvent in the liquefaction step after removing the light oil.

Next, the present invention will be described with reference to examples.

(Example) Wanduan charcoal was used as liquefaction coal. The elemental analysis values are shown in Table 1.

Liquefaction-solvent hydrogenation was repeated under the operating conditions shown in Table 2 by a coal liquefaction continuous facility having a treatment capacity of 4 / hr and a solvent hydrogenation device having a treatment capacity of 2 / hr to reach this steady state. Table 3 shows the material balance as Comparative Example 1 at that time.

In addition, as shown in FIG. 4, using the same apparatus, the material balance when the normal paraffin is removed from the heavy oil fraction having a boiling point of 350 ° C. or higher after the liquefaction step is shown in Table 3 as Comparative Example 2.

Further, Table 3 shows the material balance when the normal paraffin was removed from the medium oil fraction having a boiling point of 200 to 350 ° C. after the liquefaction step, similarly as an example. From Table 3, the liquid yield (light oil + medium oil + heavy oil) was reduced from 48% to 50 by removing the normal paraffin.
It is recognized that it increases to%.

Further, it is recognized that removing normal paraffin from the fraction having a boiling point of 350 ° C. or higher drastically reduces the amount of normal paraffin contained in the solvent and the light oil as a product, and the light oil yield.

However, when normal paraffin is removed from the boiling point fraction of 200 to 350 ° C, the amount of normal paraffin contained in the solvent is decreased, but the yield of light oil and the amount of normal paraffin in the light oil are only slightly decreased.

The solvent extraction method was used as the operation for removing the normal paraffin. That is, 5-fold amount of DMSO (dimethyl sulfoxide), medium oil, and the same amount of cyclohexane as medium oil were mixed at room temperature to separate a cyclohexane layer and a DMSO layer.

The cyclohexane layer was distilled to separate cyclohexane and regular paraffin, and cyclohexane was recovered. Also, when removing regular paraffin from heavy oil, 60
After dissolution by heating at ℃, the same operation was performed to obtain solid regular paraffin. The results of analysis of these normal paraffins by gas chromatography are shown in FIG.

From FIG. 3, it is recognized that the normal paraffin separated from the heavy oil has a peak around 25 carbon chains and the normal paraffin separated from the medium oil has a peak around 15 carbon chains.

Regular paraffins having about 15 carbon chains are useful as a raw material for surfactants, and their use amount is expected to increase in the future.

An equal amount of water was added to the DMSO layer to separate it into an aqueous layer and an oil layer, and DMSO was recovered from the aqueous layer by distillation. The oil layer was mixed with the heavy oil fraction as it was and sent to the solvent hydrogenation device.

(Effects of the Invention) As is clear from the examples, according to the present invention, the liquefied oil yield is improved.

Light oil is obtained in high yield.

A high quality liquefied product is obtained.

Easy separation of normal paraffin.

The separated normal paraffin can be an excellent industrial raw material.

It is an invention that is extremely industrially beneficial and has the effects described above.

[Brief description of drawings]

FIG. 1 is a block diagram showing the method of the present invention. FIG. 2 is a diagram showing the relationship between reaction temperature and liquid yield in this method. FIG. 3 is a diagram showing the analysis results of normal paraffin separated in Examples and Comparative Examples. FIG. 4 is a block diagram showing a conventional method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kazuhito Kurachi, 1-3, Nishi-Nagasu Hon-dori, Amagasaki City, Hyogo Prefecture, Sumitomo Metal Industry Co., Ltd. Toru 1-3, Sumitomo Metal Industries, Ltd. Central Research Laboratory (56) References Japanese Patent Publication No. 3-67549 (JP, B2)

Claims (1)

[Claims] 1. A product obtained by liquefying coal has a boiling point of 20.
After fractional distillation to components of 0 ° C or less, boiling point of 200 to 350 ° C, boiling point of 350 to 540 ° C, and boiling point of 540 ° C or more, boiling point of 200 to 35
The normal paraffin is separated from all or part of the 0 ° C component, and all or part of the separated boiling point 200 to 350 ° C component is mixed with all or part of the boiling point 350 to 540 ° C component, and the resulting mixture is A method for liquefying coal, which comprises using as a solvent for coal liquefaction after hydrogenation treatment.