JPH05320663A - Coal liquefaction method - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a method for stabilizing the properties of hydrogenated coal liquefaction solvent. [Structure] The reaction temperature for achieving the target aromatic carbon content of the circulating solvent during the solvent hydrogenation reaction is calculated by an equation according to the activity of the catalyst, and the actual reaction temperature is ± 5 to 1
A coal liquefaction method that automatically controls to an appropriate reaction temperature when the temperature fluctuation range of 0 ° C is exceeded with a reaction temperature check frequency of 20 to 40 minutes. Where f _{0 is} the aromatic carbon content of the coal liquefaction solvent before hydrogenation, f is the aromatic carbon content of the coal liquefaction solvent after hydrogenation,
k: rate constant (hr ⁻¹ ) for nuclear hydrogenation reaction, LH
SV: liquid hourly space velocity (hr ⁻¹ ), A: frequency factor, E: activation energy (kcal / mol), R: gas constant (1.98 × 10 ⁻³ kcal / mol · K), T: reaction temperature (K)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal liquefaction method, and more particularly to a coal liquefaction method for automatically controlling the aromatic carbon content of a coal liquefaction solvent.

[0002]

2. Description of the Related Art The principle of coal liquefaction is, as is already known, a slurry prepared by mixing coal and a solvent,
Hydrogen is added under high pressure in the presence or absence of a catalyst to carry out hydrocracking to produce liquefied oil such as light oil, medium oil, and heavy oil.

A typical method thereof is to mix finely pulverized coal with a coal liquefaction solvent to form a slurry, and then add a finely pulverized coal liquefaction catalyst to the mixture under operating conditions of high temperature and high pressure in the presence of hydrogen. Liquefaction, out of the resulting liquefied oil, a portion of the heavy oil and medium oil fractions are hydrotreated in the solvent hydrogenation step, and the resulting hydrogenation solvent is circulated and used as the coal liquefaction solvent. Is the way.

In the conventional method, the operator uses solvent hydrogen so that the increase in the aromatic carbon content of the solvent in the coal liquefaction reaction step and the decrease in the aromatic carbon content in the solvent hydrogenation reaction step are equal. The target value of the liquefaction reaction temperature was set and the reaction temperature was finely adjusted to adjust the aromatic carbon fraction of the coal liquefaction solvent.

[0005]

The adjustment of the aromatic carbon content in the solvent hydrogenation step is an important control index and is essential for stable coal liquefaction reaction.

However, as described above, in the conventional method, since the operator adjusts the temperature of the solvent hydrogenation reaction tower, it takes time to feed back the temperature adjustment result and stabilize the aromatic carbon fraction. It has the drawback of requiring a long period of time and having a large variation in the aromatic carbon content.

Further, when the activity of the catalyst is lowered, it is necessary to raise the reaction temperature higher than usual in order to bring the aromatic carbon content of the coal liquefaction solvent to a predetermined value. However, the target reaction temperature could not be set when the activity of the catalyst decreased, and the aromatic carbon content fluctuated significantly.

Therefore, in order to improve these drawbacks, it was necessary to develop a method for automatically controlling the aromatic carbon content of the coal liquefaction solvent.

[0009]

As a result of intensive studies to improve the above problems, the present inventors have found that the solvent hydrogenation reaction temperature can be easily adjusted depending on the activity of the solvent hydrogenation catalyst. It has been discovered that it can be predicted and controlled, and thus the present invention has been completed in which the aromatic carbon content of the coal liquefaction solvent can be automatically controlled.

That is, the gist of the present invention is that
In a hydrogenation reaction of a coal liquefaction solvent in a coal liquefaction process, a temperature fluctuation range is set to 5 to 10 ° C, and a reaction temperature check frequency is set to 20 to 40 minutes.

More specifically, coal, a solvent for coal liquefaction and a catalyst for coal liquefaction are mixed to form a slurry, and the coal slurry is pressurized and heated in the presence of hydrogen to be pyrolyzed and hydrolyzed to obtain a liquefaction. A coal liquefaction step of separating the product into a solvent and a residue, and a solvent hydrogenation step of pressurizing and heating a part of the solvent obtained in the coal liquefaction step in the presence of a catalyst to hydrogenate the solvent. In the coal liquefaction method in which the solvent after hydrogenation obtained from the hydrogenation step is circulated and used as a coal liquefaction solvent, the aromatic carbon fraction of the target coal liquefaction solvent in the solvent hydrogenation step is based on the following formula: The reaction temperature T for achieving the above is calculated, and when the reaction temperature during hydrogenation exceeds a predetermined temperature fluctuation range at a predetermined reaction temperature check frequency, solvent hydrogenation is performed until the reaction temperature reaches a target reaction temperature T. Preheater outlet temperature Changed, and controlling the temperature of the solvent the hydrogenation reactor.

[0012]

Ln (f ₀ /f)=k/LHSV...Equation

[0013]

[Equation 4] k = A · exp (−E / RT)

Here, f ₀ : aromatic carbon fraction of coal liquefaction solvent before hydrogenation f: aromatic carbon fraction of coal liquefaction solvent after hydrogenation k: rate constant (hr ⁻ for nuclear hydrogenation reaction) ¹ ) LHSV: liquid hourly space velocity (hr ⁻¹ ) A: frequency factor E: activation energy (kcal / mol) R: gas constant (1.98 × 10 ⁻³ kcal / mol ·
K) T: Reaction temperature (K)

In particular, it is preferable to set the predetermined temperature fluctuation range to a value in the range of ± 5 to 10 ° C. and to set the reaction temperature check frequency to a value in the range of 20 to 40 minutes.

The specific contents will be described below together with the operation.

[0017]

The coal used in the present invention is lignite, lignite, subbituminous coal or bituminous coal usually used for coal liquefaction.

Further, the solvent for coal liquefaction used in the present invention is a solvent obtained by further liquefying the coal-derived solvent obtained by liquefying the raw material coal and adjusting it to a predetermined aromatic carbon content. ..

FIG. 1 shows the flow of the coal liquefaction process. The raw material coal has a solvent / coal ratio of 1.0 to 1 in consideration of the properties of the coal slurry or the reactivity of the coal.
Prepare in the range of about 3.0.

Further, an iron-based disposable catalyst is used to improve the yield of liquefied oil from coal.

The amount added is preferably about 1.0 to 4.0%. Sulfur may be added as a co-catalyst to increase the activity of the iron-based catalyst.

Subsequently, the coal slurry is sent by the high-pressure slurry supply pump 3 and is reacted with hydrogen gas for a predetermined time in the liquefaction reaction tower 4 held at high temperature and high pressure to cause thermal decomposition and hydrocracking reaction. To perform.

The conditions of thermal decomposition and hydrocracking are as follows: temperature: 430-470 ° C., pressure: 150-200 kg / c
It is carried out under conditions of m ² and a residence time of 30 to 90 minutes, and a so-called coal liquefaction reaction in which the raw material coal is converted into oil or the like by such a decomposition reaction proceeds.

Regarding the liquefied product after the reaction, after unreacted hydrogen and the produced gas are separated by the gas-liquid separation equipment 5,
The distillation equipment 6 obtains product oil separated into various fractions.

Usually, as the product oil, a light oil fraction having a boiling point of 260 ° C. or lower and a part of a middle oil fraction are separated.

After the light oil and the medium oil fraction are separated and recovered, the unrecovered fraction of the medium oil fraction is further separated in the slurry decompression tank 7, and the heavy oil fraction containing unreacted coal is decompressed. It is fed to No. 8 and distilled to recover heavy oil (boiling point of 260 ° C. or higher).

A portion of the heavy oil and the medium oil is hydrogenated as a raw material and then used as a coal liquefaction solvent.

The solvent is pressurized by a pressure boosting pump 9 and heated by a solvent hydrogenation preheater 10, and then supplied to a solvent hydrogenation reaction tower 11 which is kept under high temperature and high pressure and filled with a catalyst for a predetermined time. The hydrogen donating property is enhanced by reacting with hydrogen gas to add hydrogen, and the coal is liquefied and sent to the slurry preparation tank 2 for recycling.

This hydrotreatment is carried out by Ni--Mo, Ni--
In a fixed bed reaction column packed with a catalyst such as V or Co-Mo, the above heavy oil and medium oil were heated in the presence of hydrogen at a temperature of 280 to 280.
The reaction is performed at 380 ° C. and a pressure of 50 to 150 kg / cm ² , and by this reaction, the polycyclic aromatic compound or the like in the heavy oil component in the coal is converted into a hydrogenated aromatic compound having a hydrogen donating property. ..

If the properties of the coal liquefying solvent are not constant, the yield and properties of the liquefied product will not stabilize in the coal liquefaction reaction step due to the difference in hydrogen donating properties of the solvent.

Since the present inventors have adopted the aromatic carbon fraction as an index showing the hydrogen donating ability of the coal liquefaction solvent, by automatically controlling the aromatic carbon fraction of the coal liquefaction solvent. A coal liquefaction method for stabilizing the properties of the coal liquefaction solvent was investigated.

First, the reaction temperature for obtaining the target aromatic carbon content of the coal liquefaction solvent is calculated by the following method.

The activation energy and the frequency factor are calculated from the ratio of the aromatic carbon fractions of the circulating solvent at the inlet and the outlet of the solvent hydrogenation reaction column according to the above formula.

It is assumed that this activation energy is constant throughout the operation period, and the decrease in the activity of the catalyst is caused by the change of the frequency factor.

The aromatic carbon content of the solvent has a very good correlation with the specific gravity or the refractive index (see FIGS. 2 and 3).
Therefore, the aromatic carbon fraction of the solvent at each time point is determined from the measured values of the on-line hydrometer and refractometer.

By substituting the aromatic carbon fraction of the solvent before and after the hydrogenation treatment, the activation energy and the reaction temperature thus obtained into the equation, the frequency factor A at that time is obtained.

Next, the frequency factor A obtained here, the aromatic carbon fraction of the solvent before hydrogenation, the activation energy and the target value f of the aromatic carbon fraction of the solvent after hydrogenation are substituted into the equation again. Then, the target reaction temperature T is calculated.

The outlet temperature of the solvent hydrogenation preheater is automatically changed until the reaction temperature T obtained by the above-mentioned method is reached, and the temperature of the solvent hydrogenation reaction tower is controlled, so that The aromatic carbon content of the solvent can be controlled to be constant according to the target value.

Based on this finding, the present inventors further conducted the following examination. When the fluctuation of the hydrogenation reaction temperature of the coal liquefaction solvent is large, it takes a long time for the value of the aromatic carbon fraction of the coal liquefaction solvent to return to a stable state,
It becomes a factor that changes the properties of the liquefied product.

Therefore, focusing on the temperature fluctuation range, the relationship between the temperature fluctuation range and the variation in the aromatic carbon fraction of the coal liquefaction solvent was determined.

About the effect of the temperature fluctuation range on the 1 ton / day plant when operating with American coal A charcoal shown in Table 1 on the aromatic carbon content of the coal liquefaction solvent before and after hydrotreating The results of the investigation are shown in FIG.

As can be seen from this figure, in an actual plant, the temperature range in which the temperature fluctuation range is 5 to 10 ° C. with respect to the predetermined temperature determined by the formula is the aromatic carbon fraction of the coal liquefaction solvent. We obtained the finding that it is a stable region.

FIG. 5 shows the result of investigation on the relationship between the reaction temperature and the difference in aromatic carbon content of the coal liquefaction solvent before and after the hydrotreatment.

As can be seen from this figure, the value of 5 to 10 ° C. in the above-mentioned temperature fluctuation range has an aromatic carbon content of 0.06.
It is a factor that causes fluctuations of up to 0.09, and it has been found that this range is suitable for stable operation of the plant.

Next, the frequency of checking the reaction temperature was examined. When the temperature fluctuation range is longer than the temperature range of 5 to 10 ° C. with respect to the predetermined temperature calculated by the formula, it takes a long time to return the coal liquefaction solvent to a stable state,
It becomes a factor that changes the properties of the liquefied product.

For example, if the reaction temperature is left as it is, it may cause a runaway reaction due to the rapid increase in the hydrogenation reaction rate. If the reaction temperature is left as it is, This will cause a phenomenon of increasing the aromatic carbon content.

In order to prevent these, it is necessary to determine the frequency of checking the reaction temperature. Therefore, FIG. 6 shows the result of investigation on the relationship between the frequency of checking the reaction temperature and the variation in the aromatic carbon content of the coal liquefaction solvent.

As can be seen from this figure, in an actual plant, when the reaction temperature check frequency is set to 20 to 40 minutes, it is possible to control the reaction temperature within the temperature fluctuation range described above, and the coal liquefaction It was found that the aromatic carbon content of the solvent is in the stable range.

The effects of the present invention will be described below with reference to examples.

[0050]

【Example】

[0051]

Example 1 FIG. 4 shows an example in which the present invention is applied to a liquefaction plant of 1 ton / day, which is operated by using American charcoal A.

Under the conventional operating conditions, the temperature fluctuation range of the solvent hydrogenation reaction column was not constant, so that the aromatic carbon fraction of the solvent after hydrogenation was unstable.

Next, according to the present invention, as a result of setting the temperature fluctuation range of the solvent hydrogenation reaction tower to 5 to 10 ° C., it was possible to greatly reduce the variation in the aromatic carbon fraction of the solvent after hydrogenation.

[0054]

Example 2 FIG. 6 shows an example in which the present invention is applied to a liquefaction plant of 1 ton / day, which is operated by using American charcoal A.

Under the conventional operating conditions, the frequency of checking the temperature of the solvent hydrogenation reaction column was not constant, so that the aromatic carbon fraction of the solvent after hydrogenation was unstable.

As a result of setting the frequency of checking the temperature of the hydrogenation reaction column to 20 to 40 minutes as in the present invention, the variation in the aromatic carbon fraction of the post-hydrogenation solvent can be greatly reduced.

[0057]

Example 3 FIG. 7 shows an example in which the present invention is applied when the activity of the catalyst is lowered in the operation using the American charcoal A in the liquefaction plant of 1 ton / day.

By introducing the method of the present invention, the value of the aromatic carbon fraction after the solvent hydrogenation reaction could be controlled at a constant value without being affected by the decrease in the activity of the catalyst.

[0059]

[Table 1]

[0060]

As described above, the present invention relates to an operation method for stably controlling the aromatic carbon content of a solvent in a solvent hydrogenation reaction step of a coal liquefaction plant. It has become possible to stably obtain a coal liquefaction solvent having a high aromatic carbon content.

As a result, it is possible to stably operate the entire plant while ensuring a high liquid yield in the coal liquefaction process, and the technical and economical effects of the present invention are very large.

[Brief description of drawings]

FIG. 1 is an overall flow diagram of a coal liquefaction process.

FIG. 2 is a diagram showing a relationship between a specific gravity of a coal liquefaction solvent and an aromatic carbon fraction.

FIG. 3 is a diagram showing a relationship between a refractive index of a coal liquefaction solvent and an aromatic carbon fraction.

FIG. 4 is a diagram showing the relationship between the fluctuation range of the solvent hydrogenation reaction temperature and the variation of aromatic carbon of the coal liquefaction solvent after hydrogenation.

FIG. 5 is a diagram showing a relationship between a solvent hydrogenation reaction temperature and a difference in aromatic carbon content of a coal liquefaction solvent before and after hydrogenation.

FIG. 6 is a diagram showing a relationship between a check frequency of a solvent hydrogenation reaction temperature and a variation in an aromatic carbon fraction of a coal liquefaction solvent after hydrogenation.

FIG. 7 is a diagram showing the effect of the present invention, showing the result of automatic control of the aromatic carbon fraction of the coal liquefaction solvent when the activity of the solvent hydrogenation catalyst has decreased.

[Explanation of symbols]

 2 Slurry adjusting tank 3 High-pressure slurry supply pump 4 Liquefaction reaction tower 5 Gas-liquid separation equipment 6 Distillation equipment 7 Slurry decompression tank 8 Decompression distillation tower 9 Boost pump 10 Solvent hydrogenation preheater 11 Solvent hydrogenation reaction tower

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Terashita 1 Kimitsu, Kimitsu-shi Kimitsu Nippon Steel Co., Ltd. Kimitsu Steel Works (72) Inventor, Tomoharu Mochizuki Kimitsu, Kimitsu Shin-Nihon Steel Co., Ltd. Tsu Steel Works (72) Inventor Hisaka Yamamoto 1-6-6 Totsukahigashi, Kawaguchi City, Saitama Prefecture (6) 72 Inventor Kenji Iguchi 7-26-1 Makuhari Hongo, Chiba City Chiba Prefecture Inventor Junji Yamaura Koshigaya Saitama Prefecture 4-15-1, Osawa City

Claims (3)

[Claims] 1. A liquefaction product obtained by mixing coal, a coal liquefaction solvent and a coal liquefaction catalyst into a slurry and pressurizing and heating the coal slurry in the presence of hydrogen to pyrolyze and hydrocrack it. A coal liquefaction step of separating the substance into a solvent and a residue, and a solvent hydrogenation step of pressurizing and heating a part of the solvent obtained in the coal liquefaction step in the presence of a catalyst to hydrogenate the solvent hydrogen. In the coal liquefaction method in which the solvent after hydrogenation obtained from the liquefaction process is circulated and used as a coal liquefaction solvent, the aromatic carbon fraction of the coal liquefaction solvent targeted in the solvent hydrogenation process is based on the following formula: The reaction temperature T for achieving is calculated, and when the reaction temperature during hydrogenation exceeds a predetermined temperature fluctuation range at a predetermined reaction temperature check frequency, solvent hydrogenation preheating is performed until the target reaction temperature T is reached. Change the outlet temperature of the vessel to melt A coal liquefaction method characterized by controlling the temperature of a chemical hydrogenation reaction tower. ## EQU1 ## ln (f ₀ /f)=k/LHSV...Equation 2 k = A · exp (−E / RT) where f ₀ : aromatic of solvent for coal liquefaction before hydrogenation Carbon fraction f: Aromatic carbon fraction of solvent for coal liquefaction after hydrogenation k: Rate constant for nuclear hydrogenation reaction (hr ^-1 ) LHSV: Liquid hourly space velocity (hr ^-1 ) A: Frequency factor E: Activity Energy (kcal / mol) R: Gas constant (1.98 × 10 ⁻³ kcal / mol ·
K) T: Reaction temperature (K) 2. The coal liquefaction method according to claim 1, wherein the predetermined temperature fluctuation range is set to a value within a range of ± 5 to 10 ° C. 3. The reaction temperature check frequency is set to a value in the range of 20 to 40 minutes.
The coal liquefaction method described.