JPS5952679B2 - Coal liquefaction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for liquefying coal powder by treating it with a solvent.

More specifically, petroleum is thermally decomposed at a temperature of 700℃ or higher,
A heat-treated oil obtained by heat-treating a fraction with an initial boiling point of 150°C or higher among produced oils obtained by steam cracking or catalytic cracking, or a thermally stable oil obtained by further distilling this heat-treated oil to separate the pitch component. The present invention relates to a method for liquefying coal, which is characterized by using high-temperature oil alone or mixed with coal-based heavy oil as a solvent.

Coal was used in large quantities as a solid fuel for many years until oil was produced in large quantities.

Coal has lost its place to oil because it is solid and contains a large amount of non-flammable ash.

In recent years, the reuse of coal has been attracting attention due to predictions that petroleum resources will gradually decline, and many methods have been proposed to remove ash by liquefying coal in order to eliminate its drawbacks as a fuel.

On the other hand, a major use of coal at present is as coking coal for manufacturing coasters for steel manufacturing, but due to the increasing global demand for pig iron and the depletion of coking coal as a raw material, the availability of coking coal is low. It is necessary to coagulate steam coal, and many proposals have been made for this purpose.
There is a method of using ned coal), and methods for liquefying coal for this purpose are being researched as well as for fuel use.

In addition to the conventional direct hydrogenation method, in which coal is directly hydrogenated and liquefied with hydrogen under high pressure and high temperature in the presence of a hydrogenation catalyst, coal is liquefied under milder conditions using a solvent. A method is proposed.

Methods using this solvent can be roughly divided into the following two types.

One is a method in which the reaction is carried out under hydrogen pressure, and the other is a method in which only a dissolution reaction is carried out without using hydrogen.

The solvents used in both of these two methods are mostly coal-based heavy oils such as anthracene oil, creosote oil, pitch oil, and coal tar, and petroleum-based heavy oils are not compatible with coal. It was hardly used.

However, Japanese Patent Publication No. 52-30282 discloses a method for producing ashless fuel by mixing coal and petroleum-based heavy oil, heat-treating the mixture at 400 to 450°C, and then separating the aggregates in this heat-treated product. As the petroleum-based heavy oil, crude oil residual oil from atmospheric distillation, residual oil from vacuum distillation, asphalt 1~, and naphtha thermal decomposition byproduct tar are used.

In this method, a high temperature of 400 to 450°C is required to aromatize the residual oil containing a lot of aliphatic hydrocarbons, and it also has a higher solubility in coal than coal-based heavy oil. It has the disadvantage of being low.

In addition, naphtha thermal decomposition by-product tar is highly aromatic as it is, but it contains a large amount of olefins, and if used as is, the olefins will polymerize, producing high-molecular-weight pitch and reducing the dissolution of coal. It has become clear that it has some drawbacks.

The present invention uses petroleum pyrolysis product oil including naphtha pyrolysis by-product tar, which has such drawbacks, and removes these drawbacks by appropriately treating the oil, and furthermore, uses these as a solvent to produce coal. He discovered a method to liquefy

In other words, the present invention uses a fraction having an initial boiling point of 150°C or higher of oil obtained by thermally cracking, steam cracking, or catalytic cracking of petroleum at a temperature of 700°C or higher at normal pressure or 200°C.
At a pressure of g/cm2G and at a temperature of 250 to 500℃ for 15 minutes or more
After heat treatment for 10 hours, the heat treated product or the fraction obtained by distilling it is used alone or mixed with coal-based heavy oil as a solvent, and this solvent is mixed 1 to 10 times by weight with respect to coal powder. The reaction pressure is normal pressure to 200kg/cm□G,
This is a method of liquefying coal by treating the coal at a reaction temperature of 300 to 500°C for a reaction time of 0.5 to 5 hours.

The specially treated oil produced by thermal decomposition of petroleum, which is the solvent used in the present invention, can be obtained as follows.

First, when petroleum is thermally cracked or catalytically cracked at a temperature of 700° C. or higher in the presence or absence of steam, a large amount of liquid oil is obtained in addition to gas.

Here, liquid product oil obtained as a by-product when producing olefins such as ethylene and propylene by decomposing petroleum is preferably used.

Of these liquid product oils, a fraction with a boiling point of 150° C. or higher, preferably a boiling point of 200° C. or higher, is then heat-treated under specific conditions.

This heat treatment stabilizes unstable components such as olefins, resulting in an oil suitable as a solvent for coal liquefaction.

Although a fairly wide range of conditions can be used for the heat treatment, generally the reaction pressure is from normal pressure to 200 kg/cm2G, preferably 2 to 20 kg/cm2G, and the reaction temperature is 250 to 50 kg/cm2G.
The reaction time is 15 minutes to 10 hours, preferably 1 to 5 hours.

This reaction can be carried out batchwise or continuously in one stage or in multiple stages of two or more stages.

As an example of the reaction conditions when carrying out the reaction in two stages, the following conditions can also be used.

In the first stage reaction, the reaction pressure is 2 kg/cm2G or more, preferably 5 to 20 kg/cm2G, and the reaction temperature is 250 to 36 kg/cm2.
Heat treatment is performed at 0°C, preferably 300 to 350°C, for 15 minutes or more, preferably 1 to 5 hours.

Subsequently, in the second stage reaction, the reaction pressure was 2 to 20 kg/cm□G.
, preferably 5 to 15 kg/cm2G, reaction temperature 370
~450°C, preferably 30°C under conditions of 390~430°C
The heat treatment is carried out for 1 to 10 hours, preferably 1 to 5 hours.

In this case, preferably, a method is adopted in which the raw material is continuously introduced into the first-stage stirring vessel through continuous operation, and the heat-treated oil is continuously extracted from the first-stage stirring vessel and introduced into the second-stage stirring vessel. .

This heat treatment reaction may be carried out by adding mineral acids, solid acids, Friedel-Crafts catalysts, peroxides, and other substances that promote the polymerization reaction of olefins as catalysts.

The heat-treated oil thus obtained may be used as a solvent as it is, or preferably a fraction obtained by distilling it may be used.

For example, after distilling this heat-treated oil and removing the fraction with a boiling point of 400°C or higher as pitch, the boiling point range is 200 to 400°C, preferably 24°C, from which the light fraction of the oil components is removed.
A fraction of 0 to 330°C, more preferably 240 to 300°C, is separated by distillation and, if necessary, subjected to hydrorefining for use.

As the solvent for coal liquefaction of the present invention, this heat-treated oil or a fraction obtained by further distillation of the heat-treated oil can be used alone, but coal-based heavy oils such as creosote oil, anthracene oil, coal tar, and pitch oil can be used alone. Alternatively, a mixture of fractions equivalent to the solvent recovered from coal liquefied oil can also be used as the coal liquefaction solvent of the present invention.

When using a mixture of these, the amount of heat-treated oil or the fraction obtained by distilling it is 0.1 to 10 times the volume of coal-based heavy oil, preferably 0.5 to 5 volumes. Use twice.

When these coal-based solvents are used in combination with the heat-treated oil of the present invention, poor workability due to high viscosity, which is a disadvantage of coal-based solvents, can be improved, and the hydrogen-donating properties of this heat-treated oil can also improve the coking of coal. It is effective in preventing this by taking advantage of the fact that it is higher than coal-based solvents.

The coal referred to in the present invention is ordinary coal, such as various brown coals, lignites, subbituminous coals, bituminous coals, etc., which is pulverized into powder, usually 20 meshes or less, for example 100 meshes or less. .

In the present invention, the amount of solvent used is 1 to 10 times the weight of coal, preferably 1.5 to 5 times by weight.

If the amount of solvent used is less than 1 times the weight, the dispersion of the reaction product will be poor, and uniform dispersion will not be achieved, resulting in mechanical difficulties in feeding the mixture of coal powder and solvent into the reaction vessel. be.

Furthermore, increasing the amount of solvent by more than 10 times by weight not only does not have much effect on the solubility of coal, but also has disadvantages such as lowering the efficiency of coal liquefaction treatment.

The reaction pressure for coal liquefaction treatment is normal pressure to 200 kg/
cm2G is used, but higher pressures do not have much effect on the solubility of coal, and are not practical due to high equipment and operating costs.

Also, the reaction temperature is 300-500°C, preferably 350-400°C.
A temperature of 50°C is used; however, at temperatures lower than 300°C, the liquefaction reaction of the coal does not occur and physical swelling of the coal occurs, and at temperatures higher than 500°C, coking and decomposition reactions of the coal occur.
The desired liquefaction reaction hardly occurs.

The reaction time is 0.5 to 5 hours, preferably 0.5 to 2 hours.

If the reaction time is shorter than 0.5 hours, the coal liquefaction reaction will not take place sufficiently, and if the reaction time is longer than 5 hours, the secondary polymerization reaction, decomposition reaction, etc. of the reaction products will become active and interfere with the desired coal liquefaction reaction. have the effect of

In the present invention, it is preferable to use hydrogen in this reaction.

Of course, hydrogen is not always necessary.

When using hydrogen, it is effective to prevent secondary polymerization and increase the stability of the liquefied product by hydrogenating the coal dissolved in the solvent, but even when hydrogen is not used, it is effective to hydrogenate the coal dissolved in the solvent. It is also possible to prevent secondary polymerization by taking it out of the system and cooling it.

The use of hydrogen is selected depending on the solubility of the coal used and the required properties of the liquid coal to be produced.

Further, in the coal liquefaction reaction of the present invention, a catalyst may be used to promote the reaction, but it is not always necessary.

Catalysts that are normally used in coal liquefaction reactions can be used for this catalyst, such as single or mixed oxides and sulfides of elements belonging to the iron group such as Co, Co, and Ni, or oxides of molybdenum and tungsten. and sulfides supported on various carriers, or Friedel-Crafts type catalysts such as aluminum chloride, zinc chloride, tin chloride, nickel chloride, etc., and composite oxides (silica-alumina, silica-titania, Silica/zirconia, zinc/alumina, titania/alumina, zirconia/alumina, etc.) can be used.

The liquefied coal obtained in this way, that is, the solvent-refined coal, can be either liquid or solid at room temperature depending on the reaction conditions, but when used as a non-productive fuel, it is centrifuged to remove the ash content. and filtration are performed.

When used as a caking aid for highly caking coal, ash removal is not necessary at all, or when coal with a high ash content is processed, ash removal may be performed by filtration or centrifugation. will be held.

Next, examples of the present invention will be described.

These are for specifically explaining the present invention, and the present invention is not limited thereto.

Example 1 A fraction of naphtha pyrolysis residue with a boiling point of 150°C or higher was placed in an autoclave and heat-treated at 400°C for 3 hours at 15 kg/cm2·G.

After heat treatment, the heat treated product is distilled under reduced pressure to have a boiling point of 240 in terms of normal pressure.
The fraction at ~300°C was collected.

This fraction was added 3 times by weight to Yubari coal crushed to less than 100 mesh, and then heated to 45kg/cm2G in an autoclave offshore.
, and treated at 400°C for 2 hours.

The liquefaction rate of the coal after treatment was 60%.

This treated product was filtered through a pre-coat filter to obtain solvent purified charcoal.

This refined coal is solid at room temperature, but melts when heated to about 100°C.

Elemental analysis of coking coal shows C86,1, H6,3,05,4
,N2,0. So, 3%, but solvent refined coal has C9
0,2,H6,2,N2,6. So was 1%, and its calorific value was approximately 9000 Kcal/kg compared to 8500 Kcal/kg for coking coal.

Example 2 A fraction of the naphtha pyrolysis residue with a boiling point of 150°C or higher was placed in an autoclave and heat-treated at 400°C for 2 hours under a pressure of 10 kg/cm2・G, and the heat-treated product was distilled under reduced pressure to determine the boiling point in terms of normal pressure. A fraction of 230-330°C was obtained.

Mix the same volume of distillate oil with anthracene oil, add 2 times the weight of this mixture to Taiheiyo Coal, and apply a pressure of 30 kg/cm.
□G, treated at a temperature of 410°C for 2 hours.

The liquefaction rate of the treated coal was about 80%.

Example 3 Naphtha was pyrolyzed at 850° C. and then distilled to obtain a heavy residual oil.

This fraction has a specific gravity (15℃/4℃) of 1.047 and an initial boiling point of 1.
56℃, 50% distillation point 269℃, end point 70%, 346℃
It had the following properties.

This residual oil was first heated to 350° C. through a steel pipe with an inner diameter of 4 mm, and then continuously poured into a container equipped with a stirrer for heat treatment.

At this time, the pressure was 15 kg/cm□G, and the average residence time was 1
It was time.

The heat-treated material continuously extracted from the first stage stirring vessel is heated to 400°C through the second stage pipe steel.
The mixture was placed in a second-stage stirring reactor and subjected to heat treatment.

At this time, the pressure was 10kg/cm"G, the temperature was 400℃,
Average residence time was 1 hour.

Next, the heat-treated product is continuously extracted from the second stage reactor, and the
The mixture is introduced into a flash distillation column operated at 50° C. and 10 mmHg, and separated into a fraction with a boiling point lower than 400° C. and a heavier fraction.

The distillate oil with a boiling point of 400°C or less obtained in this way is introduced into the attached vacuum distillation equipment, and the distillate has a boiling point of 240 to 30°C in terms of normal pressure.
The 0°C fraction was collected.

The specific gravity of this oil was (15°C/4°C) and 01.

(This oil is referred to as A oil) Next, 3 times the weight of this oil A was added to Yubari coal crushed to 200 mesh or less, and the mixture was treated at a reaction pressure of 60 kg/cm2G and a reaction temperature of 400° C. for 1 hour.

The liquefaction rate of the treated coal was about 60%.

Example 4 Hydrorefining was performed using oil A obtained in Example 3 as a raw material.

The catalyst used was a commercially available N1-W-A1203 catalyst, the reaction pressure was 50 kg/cm2G, the reaction temperature was 350°C, and LH3VI
I(z/H, C capacity ratio 600).

This treated oil was added 4 times by weight to Yubari coal crushed to less than 200 mesh and heated at 420℃ under hydrogen pressure at 40kg/
When treated at cm2G for 2 hours, the liquefaction rate of coal was 83%.
Met.

Example 5 Oil A obtained in Example 3 was mixed in a ratio of 1:10 with a recycled oil having almost the same boiling point range as Oil A obtained by vacuum distillation from coal liquefaction.

Next, this mixed oil was added twice by weight to Pacific coal crushed to less than 200 mesh, and the mixture was placed in an autoclave at a pressure of 60 kg.
/cm2G and a temperature of 380°C for 2 hours.

The liquefaction rate of the coal after treatment was 80%.

Example 6 Oil A shown in Example 3 was added 3 times by weight to Akahira coal crushed to 200 mesh or less to make a paste, 1 wt% of zinc chloride was added as a catalyst, and the mixture was heated to 70 kg/cm2G in an autoclave. , and treated at 380° C. for 1 hour and 30 minutes.

The liquefaction rate of the coal after treatment was 72%.

Example 7 Oil A shown in Example 3 was added 5 times by weight to Miike charcoal crushed to 150 mesh or less, and N1-W- was added as a catalyst.
Added 2 wt% of TiO2-8iO2 (5 wt% as NiO, 22% as WO3, Ti:Si = 1 mol 1 mol) catalyst and heated to 63k in an autoclave under hydrogen pressure.
g/cm2G and treated at 390°C for 2 hours.

The liquefaction rate of the coal after treatment was 79%.

Claims (1)

[Scope of Claims] 1 Oil obtained by thermally cracking, steam cracking or catalytically cracking petroleum at a temperature of 700°C or higher and having an initial boiling point of 1
The fraction above 50°C is heat-treated at a pressure of normal pressure to 200 kg/cm2G at a temperature of 250 to 500°C for 15 minutes to 10 hours, and the heat-treated product or the fraction obtained by distilling it is used alone or in combination with coal. It is mixed with heavy oil and used as a solvent.
This solvent is mixed 1 to 10 times by weight with respect to coal powder, reaction pressure is normal pressure to 200 kg/cm2G, and reaction temperature is 300 to 200 kg/cm2G.
A method for liquefying coal, characterized by treating at 500°C for a reaction time of 0.5 to 5 hours. 2. The method according to claim 1, wherein the heat treatment pressure is 2 to 20 kg/cm2 and the heat treatment temperature is 300 to 450°C. 3 The fraction obtained by distilling the heat-treated product has a boiling point of 200 to 400
2. A method according to claim 1, characterized in that the temperature is 0.degree. 4. The method according to claim 1, wherein the heat-treated oil or the fraction obtained by distilling the same is used in an amount of 0.1 to 10 times the volume of coal-based heavy oil. 5. The method according to claim 1, characterized in that the treatment of coal powder using the melting temperature 1j is carried out in the presence of hydrogen.