JPS58108289A - Liquefaction of coal - Google Patents

Abstract

PURPOSE:To improve product oil quality with effecting higher conversion to light oil, by isolating the resultant residue after a coal liquefaction, performing a solid-liquid separation of the above residue, carrying out a hydrogenation of the liquefied product and gasifying the residue using a molten metal bath. CONSTITUTION:A coal, a solvent and a catalyst are combined into a slurry through the pretreatment process 1, followed by mixing with a hydrogen gas to carry out a high-temperature reaction under high pressure in the liquefaction process 2. The resultant liquefied product is subjected to a gas-liquid separation in the process 3, followed by a solid-liquid separation of the residue containing inorganic constituents such as ash, catalyst, etc. in the process 4. Further, the resulting residue is subjected to a gasification in the presence of oxygen, water vapor etc., using a molten metal bath 8 (said metal(s) comprising at least one selected from Fe, Cr, Mo and Hi). A solid particulate generated with the gas produced is collected to use as a liquefaction catalyst. The liquefied product resulted from eliminating the residue is partly or wholly subjected to a secondary hydrogenation using a hydrogen-contg. gas.

Description

[Detailed Description of the Invention] The present invention relates to a method for liquefying coal and lightening heavy oil,
The purpose is to increase the efficiency of lightening and improve the quality of the product oil.

The principle of coal liquefaction has been known for a long time, and is the addition of hydrogen to coal to convert it into light and heavy oil components with higher hydrogen content. Since it is extremely slow, it is usually carried out at a high temperature of 400 to 500°C and under a hydrogen pressure of 100 to 500 Ky/crA or more.

Considering the economic efficiency of this liquefaction process, the reaction should be carried out at as low a temperature and pressure as possible to reduce the power cost for raising the temperature as well as equipment costs, and the high-priced hydrogen should be reacted as efficiently as possible to produce gas and water. It is important to prevent the consumption of hydrogen used for

To achieve this goal, special consideration must be given to the following two points: the catalyst in the liquefaction process and the coal slurrying solvent.

First, let us consider catalysts. The following six methods are known as coal liquefaction methods using catalysts.

The first method uses a disposable iron-based catalyst with relatively low activity, which was formerly known as the Bergius method and is currently under development in Germany. This method mixes an iron-based catalyst and coal! 100
It is a method of liquefying under high pressure hydrogen of K9/II or higher,
Liquefied oil is distilled and centrifuged 1. The catalyst used in τ' is separated by solid-liquid separation such as gravity sedimentation and is discharged from the system together with the solid residue.

The advantage of this method is that since the catalyst is disposable, there is no need to worry about catalyst deterioration due to coking, but on the other hand, cheap disposable catalysts such as ore and red mud do not have very high activity. It is necessary to add a large amount of about 5 wt% to the coal, which increases the cost of transportation from the mine and the cost of pulverizing the waste used as a catalyst, which has the drawback of increasing the cost of liquefied oil.

The second method uses a highly active catalyst such as Mo-based, Co-based, Ni-based, etc. in an ebullated bed reactor. An example is the so-called H-coal method in the United States. H-co
The al method uses M, which has high activity as a hydrogenation catalyst.

This method uses a system catalyst and liquefies it in a boiling bed. The advantage of this method is that it has high catalytic activity and the hydrogenation rate is fast, so a large amount of high-quality light oil can be obtained.However, there are problems such as loss of the catalyst due to abrasion, adsorption of metals, etc., and a decrease in catalytic activity due to coking. Therefore, a part of the catalyst is extracted and a regeneration process is set up, but since the regeneration is not complete, a new catalyst containing highly flexible metals such as Mo and Ni must be replenished secondarily, and the system is no longer available. Liquefied oil has drawbacks that lead to high costs.

The third one is as shown in Patent Application No. 99647 of 1982,
This is a method in which a fine powder solid entrained in the gas is used as a catalyst when the liquefaction residue is gasified in a molten metal bath, and has the excellent advantage of being highly active and allowing the catalyst to be recycled within the liquefaction system.

According to this method, it is possible to convert about 50% of dry coal into oil with a boiling point of 568 DEG C. or less by adding a catalyst in an amount of 1 to 1 degree, although it varies depending on the type of coal.

Next, considering the solvent, the role played by the solvent is that because coal is a solid, it is difficult to continuously feed a constant amount into a high-pressure system of about 200 K9/d, so finely pulverized coal is It mixes with a solvent to form a slurry, making it easier to feed into the system.
1 Additionally, the solvent 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 in forming a slurry but also in relaxing the liquefaction reaction conditions.

Therefore, it is desired that the solvent has properties such as a medium oil that facilitates operation and a hydrogen donating ability that promotes the reaction.

Conventionally, as a solvent for coal liquefaction for this purpose, medium/heavy oil, which is a product obtained by liquefying coal, has been recycled as it is, or medium/heavy oil that has been hydrotreated has been used. Ta. In this case, in order to stabilize the slurry, the heavier the solvent, the higher the affinity with the coal, and the higher the specific gravity, which prevents the coal from settling and prevents coking of the coal due to solvent evaporation. Therefore, it is considered suitable.

Therefore, it is best to use heavy oil obtained by liquefying coal, particularly a hydrotreated fraction with a boiling point of 400° C. or higher, as the solvent.

However, among the coal liquefaction products, the main heavy components are substances called asphaltenes and pre-asphaltenes, which have a boiling point of 450℃ or higher and a molecular weight of several 100s to several 100s.
It is a polymer compound with 0 aromatic nuclei, and even if it is liquefied in one stage using a catalyst, it will produce more than 20% of the amount per coal.

Therefore, since the heavy components have low added value as a product, they are either solid-liquid separated to produce fuel oil, or solid-liquid separated and further refined to produce light oil.

The method is called secondary hydrogenation and is 5ect in the United States.
This method is adopted by law.

The reason for performing solid-liquid separation is that ash poisons the catalyst during secondary hydrogenation, and to separate asphaltenes and glare asphaltenes from inorganic materials that cannot be separated from inorganic materials such as ash and catalyst during distillation. It is.

Based on this method, asphaltenes and glare asphaltenes, which have low value as products, are separated, and then hydrocracked.
Not only is it possible to improve the light oil yield, but if a part of the hydrogenation product is recycled to the liquefaction process as a solvent,
Becomes a high quality liquefaction solvent.

The present invention is based on the above-mentioned prior art and is a method that is further improved.

That is, the present invention gasifies the residue after coal liquefaction using a molten metal bath, and at this time, the fine powder solid produced from the metal bath along with the gas is separated and collected from the gas, and the residue is subjected to a liquefaction catalyst. a solid-liquid separation step that uses a solvent, a hydrogen-containing gas, and the catalyst to separate a liquefied residue containing an inorganic substance whose main component is a single-coal catalyst, and a liquefied product from which the residue has been removed. This method of liquefying coal is characterized by comprising a second hydrogenation step in which all or part of the coal is further hydrogenated using a hydrogen-containing gas.

According to the present invention, not only lightening and quality improvement of the product can be achieved through the secondary hydrogenation treatment, but also the recycling of the secondary hydrogenation product allows The stabilizing solvent can improve the stability and liquefaction efficiency of the slurry, and it is also possible to obtain about 60% oil per dry coal.

Next, the present invention will be explained with reference to a schematic flow sheet shown in FIG.

The pulverized raw coal, solvent, and catalyst are slurried in coal pretreatment step 1, mixed with hydrogen gas, and reacted at high temperature and pressure in liquefaction reaction step 2. The liquefied product undergoes gas-liquid separation in step 3, and then solid-liquid separation of the liquefied residue containing inorganic substances such as ash and catalyst in step 4.

As shown in Patent Application No. 99647 of 1981, the liquefaction catalyst converts the residue after liquefaction of coal into oxygen, water vapor, etc.
The gas is blown into a metal bath 8 consisting of at least one or more of e, Cr, Mo, and Ni for gasification, and the fine powder solids accompanying the generated gas are collected at 9 and used. It can be used as a catalyst as it is, pre-sulfurized with a sulfur compound as shown in 10, or added to the liquefaction process together with elemental sulfur.

The generated gas from which solids have been separated is purified in step 11 and becomes a source of hydrogen gas.

Liquefaction reaction conditions are 400-460℃, hydrogen pressure 150-20
0 K9Icell, residence time may be 0.5 to 2 hours.

The solid-liquid separation method may be any method such as centrifugation, gravity sedimentation, Kerr-McGee's critical 5 solvent method, or the like.

After removing the residue, the liquefied product is subjected to distillation 5 to separate light oil, and then subjected to secondary hydrogenation at high temperature and pressure in 6 using hydrogen gas and a catalyst, resulting in a light oil and a high hydrogen donating ability of the solvent. It can be measured. Next, in step 7, the oil is fractionated into light oil and medium oil by distillation, and all or part of the medium oil is recycled and used as a liquefaction solvent.

The secondary hydrogenation step consists of Al 203 , P2O6,T
io2, 8 io, Mo, Ni supported on a carrier consisting of at least one type of MgO.

It is carried out in a fixed-bed or ebullated-bed reactor using a catalyst containing Co or the like. The reaction conditions are 650-450
°C, hydrogen pressure 50~i 50 K9/a11 residence time 0.
5 to 2 hours is sufficient.

The present invention will be explained in more detail with reference to Examples below.

Example 1 A liquefaction experiment was conducted using the following six methods A, B, and C shown in flow sheets in FIGS. 2, 6, and 1.

The conditions for each step (a) to (e) in these three methods were as follows.

(a) Coal Pretreatment Step The coal shown in Table 1 was pulverized to a total amount of 100 pieces or less, and then mixed with a catalyst, elemental sulfur, and a solvent. The solvent was added at twice the weight of the coal, the catalyst was added at 1%, and the sulfur was added at a ratio of 0.5%.

Table 1 (b) Liquefaction reaction step (-secondary hydrogenation step) Using a continuous liquefaction reactor with a coal throughput of 1 to 9/hour, Temperature: 450°C,
The hydrogen reaction pressure was 180 K9/cd% and the reaction time was 1 hour.

(c) Solid-liquid separation process A reactor with an inner diameter of 20 cWL and a capacity of 151 was used, which could be extracted from the bottom.

Add benzene to the liquefied product and heat to 60°C, 9/9 to 50°C.
Extraction was performed for 30 minutes under the conditions of d. The precipitated residue containing minerals was extracted from the bottom, and the remainder together with benzene was extracted from the top, and then the benzene was separated and solid-liquid separation was performed.

2) Secondary hydrogenation process using fixed bed continuous reactor with treated liquid volume 2 to 9/hour, temperature 420°C, hydrogen reaction pressure 100 Kf/cl XLH8
Under the condition of V=1/hour, Mo −N i −, A l
This was carried out using a 203 series catalyst.

(e) Molten metal bath operation The liquefaction residue is blown into a molten iron bath with a bath temperature of 1,570°C together with oxygen gas to produce gas, and the entrained fine powder solids are collected and recycled for use as a liquefaction catalyst. did.

Oxygen gas has a pressure of 11 Ky/crls and a flow rate of 3 Nni.”
It was 7 o'clock. The composition of the generated gas is Co 71%, H2
26%, co, 2.2%, and the finely divided solids content in the gas was 69g1Nd.

From the I Ky coal a residue of more than 0.25 Kp was produced, and from the iron bath 90.26 Ni gas could be produced, corresponding to 10 g of finely divided solid.

Next, six methods A, B, and C will be shown.

Method A As shown in Figure 2, coal is mixed with hydrogen gas, a catalyst, and a solvent (1
After liquefying the mixture (80-400°C fraction), it is introduced into a gas-liquid separation tower to separate gas, water, etc., and the remainder is further separated into solid-liquid,
Separates inorganic substances such as ash and catalyst. Furthermore, the liquefied product after solid-liquid separation is distilled, and the fraction at 180 to 400°C is recycled and used as a solvent.

Method B As shown in Figure 6, in the above method A, 180 to 40
The fraction at 0°C is circulated as a solvent, and the remainder is used as Mo-Ni.
- Further secondary hydrogenation treatment is performed using the A1103 catalyst and hydrogen-containing gas to increase the liquid yield.

Method C corresponds to the present invention, and as shown in FIG.
A second hydrogenation treatment is further performed using a Ni-Al2O3 catalyst and a hydrogen-containing gas, and the hydrogenated product is recycled as a solvent.

An experiment was conducted under the above conditions, the liquefied product was separated by simple distillation, the amount of solvent mixed with coal was subtracted, and each yield per unit of coal was calculated. The results are shown in Table 2.

Table 2 Compared to Method A, in Method B, as7artene is hydrocracked by secondary hydrogenation to produce oil, which adds up and increases the yield.

In addition, in method C, not only the increment of the secondary hydrogenation product but also
The yield is significantly increased because the secondary hydrogenation product acts as a good hydrogen-donating solvent. In addition, the secondary hydrogenation product is hydrocracked in the liquefaction reaction step, increasing the yield of light oil.

It can be seen that the coal conversion rate increased significantly, and almost all of the coal was converted to benzene-soluble content.

Example 2 Bath temperature 1,550°C Ni 8.8 s, Mo 9.1 s
A catalyst and a liquefied residue containing ash were blown from the top of the bath together with oxygen and water into an iron alloy bath containing C5,5 and C60.

Oxygen has a pressure of 11 Kpeals and a flow rate of 7.1 Nn? /Time,
The steam temperature was 300° C., the pressure was 12 K9/al11, and the flow rate was 1.15 at 97 hours.

The resulting gas contained fine powder solids of 409/Nrd, which were collected with a Venturi scrubber.

This finely divided solid contains 2% Mo, 3% Ni, 60%
of Fe and 6% of sulfur.

This finely powdered solid was used as a catalyst and added in an amount of 1 g to coal, and coal liquefaction was carried out according to Method C of Example 1.

In addition, in order to see the effect of the addition method of sulfur added to the catalyst, three addition methods shown in Table 3 were used.As is clear from Table 3 and Table 6, when a fine powder solid containing KMo and Ni was used as a catalyst. In this case, the total oil yield is higher than that of Fe alone.

It is also clear that although there is activity without adding sulfur, it is better to sulfurize with H2S or add it together with elemental S.

[Brief explanation of drawings]

FIG. 1 is a schematic flow sheet of the present invention, and FIGS. 2 and 6 are schematic flow sheets showing Method A and Method B in Example 1. 1... Coal pretreatment 2... Liquefaction reaction (-fire hydrogenation) 6... Gas-liquid separation 4... Solid-liquid separation 5.7... Distillation 6... Secondary hydrogenation 8. ...Metal bath 9...Dust collection 10...Pre-sulfurization 11...Gas purification agent Patent attorney Satoshi Sasaki

Claims (1)

[Claims] (1) Gasification of the residue after coal liquefaction using a molten metal bath
~ At that time, the fine powder solids produced along with the gas from the metal bath are separated and collected from the gas, and the residue is gasified using a liquefaction catalyst, and the solvent, hydrogen-containing gas, and the catalyst are combined. The first hydrogenation step of the coal used, the solid-liquid separation-1' step for separating the liquefied residue containing inorganic substances mainly composed of ash catalyst from the liquefied product, and the liquefied product from which the residue has been removed. A method for liquefying coal, comprising a second hydrogenation step in which all or part of the coal is further hydrogenated using a hydrogen-containing gas. (2) The method according to claim 1, wherein the molten metal bath is a metal bath consisting of at least one or two or more of iron, chromium, molybdenum, and nickel. (6) The method according to claim 1, in which sulfur or a sulfur-containing compound is added to the separated and collected fine powder solid as a catalyst. (4) The method according to claim 1, wherein all or part of the hydrogenated product produced from the second hydrogenation step is recycled to the first hydrogenation step as a solvent. −