JPS5917152B2 - Coal liquefaction method - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for liquefying coal, and aims to improve the performance of a solvent used when liquefying coal, as well as simultaneously improving the safety of equipment operation and increasing the efficiency of the reaction. That is.

Coal liquefaction is aimed at producing light oil and heavy oil, and the principle of the liquefaction reaction has been known for a long time.

The liquefaction principle is usually to convert coal, which is a high molecular compound, into light and heavy oil components, which are low molecular compounds.
The method involves adding hydrogen to coal and liquefying it under high temperature and pressure.

A solvent is generally required in such a coal liquefaction reaction, and the reason for this is that coal is solid, so 200%
It is difficult to continuously feed a constant amount of coal into a high-pressure system of about 5,000 yen, so pulverized coal is mixed with a solvent to form a slurry to facilitate feeding into the system.

On the other hand, the solvent also has the ability to uniformly disperse and stabilize the liquefied product.

Further, when the solvent has hydrogen donating ability, it plays an important role not only for forming a slurry but also directly influencing the liquefaction reaction.

Therefore, it can be said that the best properties that the solvent should have are that it is a medium oil that facilitates operation, and that it has hydrogen donating ability that promotes the reaction.

Conventionally, as a solvent for coal liquefaction, a heavy component obtained by liquefying coal has been recycled as it is, or a solvent obtained by hydrogenating the heavy component has been used.

This heavy component has a strong affinity with coal and has an appropriate viscosity, so when mixed with pulverized coal to form a slurry, it forms a stable slurry without solid-liquid two-phase separation. It was possible.

That is, if the slurry undergoes solid-liquid separation and solid coal powder settles in the equipment piping, causing pipe blockage or slurry drift, it will seriously impede the continuous operation of the equipment.

However, a slurry made by directly using the heavy components obtained by liquefying coal as a solvent does not exhibit such a precipitation phenomenon and is suitable as a slurry-forming solvent.

However, although this heavy component has the ability to act as a medium oil, it has a poor ability to donate hydrogen to coal in a liquefaction reaction.

In order to make the heavy component have the above-mentioned hydrogen donating ability in addition to its ability as a medium oil, the heavy component is generally subjected to a hydrogenation treatment.

This hydrogenation process converts heavy components into hydrogen-donating components.

This hydrogen-donating component donates hydrogen to coal under liquefaction reaction conditions and contributes to hydrocracking and liquefaction of coal.

By the way, the highly prized component obtained by liquefying coal is a mixture composed of various substances, and among these are originally
There are also substances that are difficult to convert into hydrogen-donating components, or substances that generate by-product gases such as methane and ethane during the hydrogenation process.

Due to these various factors, the yield of hydrogen-donating components obtained by hydrotreating heavy components obtained by liquefying coal is generally about 30% at maximum.

This means that even if the hydrogenation reaction conditions are harsh, by-product gas and
The yield of light oil only increases, but the yield of hydrogen-donating components does not increase; on the contrary, what is once converted to hydrogen-donating properties is further hydrogenated and undergoes decomposition, etc., and becomes non-hydrogen-donating components. This is because the yield of the hydrogen-donating component decreases.

On top of that. When a solvent with a low hydrogen-donating component content is used, the amount of hydrogen for liquefying coal is insufficient.

Therefore, either reduce the amount of coal processed per unit amount of solvent or
Alternatively, if the amount of coal processed cannot be reduced, the liquefaction yield will decrease unless hydrogen gas is pressurized into the liquefaction reaction system to compensate for the hydrogen shortage.

As is well known, the liquefaction of coal is generally carried out at a reaction temperature of 400~
Because the process is carried out at a high temperature and pressure of 450℃ and a pressure of 100 to 200℃, it becomes more dangerous to introduce hydrogen gas, which has the property of igniting at around 400℃, into the high-pressure liquefaction reaction system, and it is difficult to supply hydrogen. Requires advanced technology.

However, if hydrogen gas is not used, the liquefaction efficiency decreases, making it uneconomical.

Until now, technologically excellent inventions such as the SRC method and the EXXON method in the United States have been known for methods of liquefying coal, but the economic efficiency, safety, and stability of operation have not yet been confirmed. There is still room for consideration.

This invention proposes a coal liquefaction method using a coal liquefaction solvent that has high hydrogen donating ability and high reaction efficiency, and is free from operational troubles due to poor slurry properties and has high safety in equipment operation. It is something.

The inventors subdivided the product obtained by liquefying coal into appropriate boiling point ranges, and compared and studied the performance of each fractionated component as a solvent for coal liquefaction.

That is, the fraction with a boiling point of 200°C or higher obtained by liquefying coal is a component with a boiling point of 200 to 210°C (hereinafter referred to as component A for convenience of explanation), a component of 211 to 230°C (hereinafter referred to as component B for convenience of explanation), 231 C. or higher (hereinafter referred to as component C for convenience of explanation) and examined the performance of each component, it was found that component A was relatively rich in hydrogen donating ability.

Furthermore, when each fractionated component was subjected to hydrogenation treatment, it was found that component B was most easily converted into a hydrogen-donating component in a high yield.

Therefore, if the hydrotreated component B and component A are mixed and used as a coal liquefaction solvent, the coal liquefaction reaction will be greatly accelerated since both components are rich in hydrogen-donating components.

However, since the amounts of component A and component B produced are relatively small, a problem arises in that they are insufficient in quantity when used as a solvent for coal liquefaction.

As a method for solving this problem, the inventors have previously applied for a coal liquefaction method (Japanese Patent Publication No. 56-3571).
No. 2).

In this invention method, the boiling point obtained by liquefying coal is 200℃.
The above fractions were hydrogenated and dealkylated to increase the amount of components A and B produced.

However, through subsequent research, the inventors found that there were still some points to be improved in the invention of the earlier application.

One of them is to hydrogenate and dealkylate the entire fraction with a boiling point of 200° C. or higher.

This method has the disadvantages that the amount of treatment is too large relative to the amount of component A or component B obtained, and that expensive hydrogen is likely to be used in large quantities for reactions other than dealkylation. be.

Another problem is that high pressure is difficult to utilize effectively.

That is, the invention of the earlier application has a boiling point of 2 obtained by liquefying coal.
Heavy oil at a temperature of 00°C or higher was first hydrotreated, then the A component and B component were separated, and the B component was further hydrotreated.

Therefore, the fraction with a boiling point of 200° C. or higher that has been hydrogenated under high pressure is returned to normal pressure to separate the A and B components, and then the B component is hydrogenated again under high pressure.

The inventors conducted various studies to improve the above-mentioned disadvantages existing in the invention of the earlier application, and found that among the fractions with a boiling point of 211 to 25
By hydrotreating the 0°C fraction, dealkylation progresses, and the amount of component A or B produced increases to the same level or more than when the entire fraction with a boiling point of 200°C or higher is hydrotreated. There was found.

Since the heavy components obtained by liquefying coal are a mixture of various substances, some of these substances do not originally participate in the dealkylation reaction or tend to inhibit the dealkylation reaction. expected to contain ingredients.

Therefore, by hydrogenating the boiling point 211-250°C fraction, A
The fact that a large amount of the component or component B can be obtained means that the components within this boiling point range are likely to be dealkylated, and it is thought that there are few reaction-inhibiting components within this range.

According to the method of this invention, by hydrogenating and dealkylating components that have been separated in advance by distillation etc., components that are easily converted into hydrogen-donating components can be obtained in high yield. It becomes possible to perform the next hydrogenation treatment as it is, that is, while maintaining the high pressure.

Therefore, the product obtained by liquefying coal has a boiling point of 200
After separating the ~210°C component (A component) and the 211~250°C component (hereinafter referred to as the component for convenience of explanation),
If the product obtained by hydrotreating component D is further hydrotreated and mixed with component A and used as a solvent for coal liquefaction, the above-mentioned quantitative problem will be solved and the product will have excellent hydrogen donating ability. Becomes a solvent.

However, it was found that when this mixed solvent was mixed with coal to form a slurry, solid-liquid two-phase separation occurred and the state of the slurry was poor.

This is because the viscosity of the mixed solvent of component A and hydrogenated component D is considerably lower than that of conventionally used liquefaction solvents, and because it is rich in hydrogen-donating components, it has relatively low aromaticity. It was confirmed that this is due to the deterioration of affinity with highly aromatic coal.

Therefore, the inventors investigated a product obtained by liquefying coal, which has a high viscosity and relatively high aromaticity, and has a boiling point of 25%.
As a result of investigating a method of mixing an appropriate amount of a component above 1°C (hereinafter referred to as component E for convenience of explanation) into the slurry, the condition of the slurry was greatly improved, the problem of solid-liquid separation was solved, and the reaction became stable. It has been confirmed that this will be done.

However, component E has almost no hydrogen-donating ability, so if a large amount of this component E is mixed with component A or hydrogenated component D, the hydrogen-donating ability of the solvent as a whole will decrease, and under general liquefaction conditions. The mixing ratio of solvent and coal is (
Mixing ratio of solvent to coal 1) 1 to 5, the liquefaction rate of coal will decrease significantly if the content of E component exceeds 50%, so the mixing ratio of E component in the solvent should be 50% or less. It turned out to be.

For example, at a mixing ratio of 5, it is possible to liquefy coal even if 50% of the E component is mixed, but at a mixing ratio of 3 to 1, a decrease in the liquefaction rate can be prevented by reducing the content of the E component.

Based on the above facts, this invention extracts components with a boiling point of 200 to 210 °C and boiling points of 211 to 250 °C from the product obtained by liquefying coal.
°C component, after separating the components above 251 °C, the boiling point is 21 °C.
After hydrogenating the 1-250°C component and further hydrogenating the resulting product, it is mixed with the whole amount or a part of the component with a boiling point of 200-210°C, and then 50% or more of the mixture has a boiling point of 251°C or higher. It is characterized in that 50% or less of the components are mixed and the resulting mixture is used as a solvent for coal liquefaction.

Next, an example of an apparatus for industrially implementing the method of this invention will be described based on the block diagram shown in FIG.

In the figure, 1 is a stirring tank for stirring and mixing coal 7 and solvent 8;
2 is a heating furnace, 3 is a dissolution tank, 4 is a distillation column, and 5 and 6 are hydrogenation groups, respectively.

That is, the coal 7 and the solvent 8 are sufficiently stirred in the stirring tank 1,
Mix to make a slurry.

This slurry is sent into the heating furnace 2 by a force pump and heated to a predetermined temperature.

- The heated slurry completes the liquefaction reaction in the dissolution tank 3.

Since some gas is generated here, it is extracted from the upper part and separated into gas, light oil, etc.

The liquid in the dissolution tank 3 overflows and enters the distillation column 4, where the reactants are separated into light components with a boiling point of 200°C or less and a boiling point of 2
00~210°C component (A component) and boiling point 211~250
It is separated into a component with a boiling point of 251°C or higher (component E).

Then, component D is introduced into the next hydrogenation group 5 together with hydrogen gas 9 and subjected to hydrogenation treatment.

The hydrogenated reactant is then introduced into the next hydrogenation group 6 together with hydrogen gas 9 to be hydrogenated.

Then, the A component and the E component are mixed with the D component that has left the hydrogenation group 6, and the mixture is recycled and used as a coal liquefaction solvent.

Examples of the present invention will be described below.

Example 1 Using a rotary autoclave with an internal volume of 51 cm, a solvent-free hydrogenation experiment of coal was conducted under the conditions of a reaction temperature of 450° C., a reaction time of 240 minutes, and an initial hydrogen pressure of 100% G.

After the reaction, a portion of the gas in the autoclave is extracted and used as a gas analysis sample, and the remaining components in the autoclave are separated into components with boiling points of 200°C or lower (hereinafter referred to as O components) and boiling points of 200 to 210°C in an atmospheric distillation column. °C component (
A component), boiling point 211-230°C component (B component), boiling point 231-250°C component (hereinafter referred to as F component), boiling point 2
It was separated into a component with a temperature of 51°C or higher (component E).

This solvent-free hydrogenation experiment of coal was carried out at 1 kg/time.

It was carried out five times under the same conditions, and a total of 5 kg of coal was liquefied.

Table 1 shows the product yields obtained as an average value of the five experiments.

Of the obtained product, 115 pieces each of components A, B, F, and E were sampled and remixed to adjust the components with a boiling point of 200°C or higher, and 115 pieces each of components B and F were sampled. The mixture was remixed and a component with a boiling point of 211 to 250°C (component D) was adjusted.

These two readjusted solvents were dealkylated using a Cr catalyst under the reaction conditions of a reaction temperature of 450° C., a reaction time of 60 minutes, and an initial hydrogen pressure of 30 G using the same experimental apparatus as described above.

The product after dealkylation was separated into the same components as above in an atmospheric distillation column.

Table 2 shows the yield (maximum) of each fractionated component based on raw coal (anhydrous and ashless standard).

As is clear from the results in Table 2, components with a boiling point of 200°C or higher (A+B+F+E) or components with a boiling point of 211 to 250°C
When dealkylating the °C component (B+F or D component), the amount of A+B component is reduced to the original yield after liquefaction (14.5%
-Table 1), the increase was 21.0%, is, and i%, respectively.

In particular, in the case of component D, if 3.3% of the original component A is added, the total amount of components A and B after dealkylation becomes 21.4%, and when components with a boiling point of 200°C or higher are dealkylated. An A+B component equal to or greater than that can be obtained.

Example 2 The A and E components obtained in Example 1 and the dealkylated D component (referred to as the Do acid component) were mixed in an internal volume of 500
Reaction temperature 400℃ in TLl shaking autoclave
Co-
Hydrotreating was performed using a Mo catalyst to obtain a hydrotreated product A' 5 D'01 B'.

Using the thus obtained A', D'os E' and the original A, D, E components as a solvent for coal liquefaction,
Reaction temperature 400℃, reaction time 60 minutes, initial nitrogen pressure 705G
, a coal liquefaction experiment was conducted at a mixing ratio of 5.

Benzene was extracted from the liquefied product to calculate the liquefaction rate.

The results are shown in Table 3. From the results in Table 3, A
It can be seen that the liquefaction rate is very good when the components are used as solvents.

Therefore, component A can be fully utilized as it is as a liquefaction solvent without being subjected to hydrogenation treatment.

Next, it can be seen that when the hydrogenated A', D'o, and E' acid component solvents are used, the liquefaction rate of the A' and D'o components is high.

Especially for the D'o component, the original glue.

Considering that the liquefaction rate when using these components is as low as 24.9%, the liquefaction rate is dramatically increased by the hydrogenation treatment.

On the other hand, in the case of A' component, the liquefaction rate of the original A component is 80
% or more, it can be seen that there is no need for hydrogenation treatment, and that hydrogenation treatment has no effect.

Therefore, take the A component.

D' whose components were hydrogenated. If the components are mixed and used as a coal liquefaction solvent, it can be expected that a good coal liquefaction rate will be obtained.

Example 3 Among the components obtained in Example 1, component A and D'.

Using an appropriate amount of component E as a solvent, the reaction temperature was 400°C and the reaction time was 60 minutes in a shaking autoclave with an internal volume of 500 m1.
A coal liquefaction experiment was conducted under the conditions of an initial nitrogen pressure of 70 G and a mixing ratio of 5.

Then, the product after liquefaction was extracted with benzene, and the liquefaction rate was calculated.

The results are shown in Table 4. From Table 4, when the content of A+D'o components is low, the liquefaction rate is low, but in the case of a solvent containing 60% or more of A+D'o components, the liquefaction rate is good at approximately 80%. I understand.

Therefore, when the mixing ratio is 5, it is presumed that in order to obtain a high liquefaction rate, the content of the A+'o component in the solvent should be 50% or more.

Next, using a high-pressure flow experimental device with a slurry processing rate of 21/Hr, under the conditions of room temperature and pressure of 50 to 50 G, a typical example of the mixed solvent shown in Table 4 was used as a coal slurry solvent. A slurry flow experiment was conducted using this method.

The properties of the slurry at that time and the properties of the slurry after flow are also listed in Table 4.

As is clear from the results in Table 4, when the slurry was formed using only the A+D'o component as a solvent, the mixing ratio of the solvent and coal after flow was considerably high.

That is, it can be seen that the slurry underwent solid-liquid two-phase separation during flow, and solid coal powder remained precipitated in the experimental equipment.

On the other hand, by mixing component E as a solvent component, the mixing ratio of the solvent and coal before and after the experiment was almost constant, and it can be confirmed that mixing component E is very effective in stabilizing the slurry.

[Brief explanation of drawings]

The drawing is a schematic diagram showing an example of an apparatus for carrying out the method of the invention. In the figure, 1... stirring tank, 2... heating furnace,
3...Dissolution tank, 4...Distillation column, 5,6
...Hydrogenated group, 7...Coal, 8...
...Solvent, 9...Hydrogen.

Claims (1)

[Claims] 1 Boiling point 200-2 from the product obtained by liquefying coal
After separating the 10°C component, the 211-250°C component, and the 251°C or higher component, the component with a boiling point of 211-250°C is hydrogenated, and the resulting product is further hydrogenated, with a boiling point of 200-210°C. A method for liquefying coal, which comprises mixing the whole amount or part of a component, further mixing 50% or more of the mixture with a component with a boiling point of 251°C or higher and 50% or less, and using the resulting mixture as a solvent for coal liquefaction. .