CN110055095B

CN110055095B - Method for preparing coal liquefaction raw material

Info

Publication number: CN110055095B
Application number: CN201910319765.4A
Authority: CN
Inventors: 王洪学; 舒歌平; 谢晶; 章序文; 杨葛灵
Original assignee: China Shenhua Coal to Liquid Chemical Co Ltd; China Energy Investment Corp Ltd; Shanghai Research Institute of China Shenhua Coal to Liquid Chemical Co Ltd
Current assignee: China Shenhua Coal to Liquid Chemical Co Ltd; China Energy Investment Corp Ltd; Shanghai Research Institute of China Shenhua Coal to Liquid Chemical Co Ltd
Priority date: 2019-04-19
Filing date: 2019-04-19
Publication date: 2021-02-23
Anticipated expiration: 2039-04-19
Also published as: CN110055095A

Abstract

The invention provides a method for preparing a coal liquefaction raw material, which comprises the following steps: conveying the coal powder to a distributor, so that the coal powder falls into a cylindrical dipping absorber connected with the distributor after being dispersed by the distributor; conveying the catalyst to a spray head inside the dipping absorber for atomization so as to spray the catalyst on the surface of the coal powder falling from the distributor and be absorbed by the coal powder; and conveying the coal powder mixed with the catalyst from the impregnation absorber into a dryer for drying and grinding, thereby preparing the coal liquefaction raw material with certain granularity and water content. The method integrates the preparation of the catalyst into the preparation process of the raw material coal powder, so that the direct coal liquefaction does not need to independently set a catalyst preparation device, thereby greatly saving the investment cost of the device and greatly reducing the water consumption and the energy consumption of the production; meanwhile, the catalytic active components are uniformly dispersed on all coal liquefaction feeding coal powder, so that the conversion rate of coal and the yield of coal liquefaction oil can be greatly improved.

Description

Method for preparing coal liquefaction raw material

Technical Field

The invention relates to the field of coal chemical industry, in particular to a method for preparing a coal liquefaction raw material, and more particularly to a method for integrally preparing the coal liquefaction raw material directly through a liquefaction catalyst and raw material coal.

Background

Coal resources are relatively rich in China, petroleum and natural gas resources are relatively short, the petroleum has high external dependence, and the energy safety of China is seriously threatened. Direct coal liquefaction is a clean coal technology that converts coal into liquid products under the conditions of high temperature and high pressure by the action of a hydrogen-donating solvent and a catalyst. The main products of the process are high-quality gasoline, jet fuel oil, diesel oil, aromatic hydrocarbon and carbon chemical raw materials, and the byproducts are fuel gas, liquefied petroleum gas, sulfur, ammonia and the like, and the thermal efficiency of the process is up to 70%. Therefore, the direct coal liquefaction for producing the liquid fuel is an important way for clean and efficient conversion and utilization of the coal. The first megaton-level direct coal liquefaction production line in China successfully operates for over nine years from the production in 2008 to the present, and the design and construction of the second production line and the third production line are currently carried out.

The direct coal liquefaction process is a complex physical and chemical process, and has a plurality of influencing factors, which mainly comprise: the type and nature of the coal, the reactor form, the catalyst, the solvent, the reaction temperature and time, the atmosphere, etc. The catalyst can promote the pyrolysis of coal and accelerate the hydrocracking of pyrolysis macromolecules, and improve the yield of oil and the quality of oil in products, so that how to develop and design the catalyst with high catalytic activity, good selectivity and low cost is always a hotspot of direct coal liquefaction research.

Iron element can be combined with sulfur under the coal liquefaction condition to be converted into coal liquefaction active phase Fe_1-xS, and thus a large number of inexpensive iron-containing substances such as natural iron ore, red mud as a by-product of aluminum production, synthetic ferrite, sulfides, etc. are used as the direct coal liquefaction catalyst. The iron element is used as a main active component, and a small amount of elements such as nickel, molybdenum, tungsten and the like with high hydrogenation activity are introduced as secondary active components to improve the activation capability on hydrogen, so that higher coal liquefaction oil yield is obtained, but the relatively expensive price of the elements such as nickel, molybdenum, tungsten and the like limits the large-scale use. Improving the activity and the dispersibility of the iron-based catalyst has been the key point of the development of the direct coal liquefaction catalyst. The adoption of liquefied raw material coal dust as a carrier to disperse active species is a skillful and efficient way to improve the activity of the iron catalyst. The raw material coal powder is used as a carrier, so that not only can the precursor iron species be well dispersed, but also the catalytic active component can be in zero-distance contact with the reaction raw material, and a better catalytic effect can be exerted. For example, based on the technology of patent CN 200410070249.6, etc., the world is only industrialized in millionsA ton coal direct liquefaction device uses a catalyst described in patent CN03153377.9, namely, coal liquefaction raw material coal powder (less than 150 mu m, and the water content is 0.5-4 wt%) which is ground and dried by about 1/6 is mixed with a ferrous salt solution, subjected to alkaline solution precipitation, air oxidation, filter pressing, subsequent drying and grinding and the like, and then mixed with oil coal slurry containing about 5/6 raw material coal and sent into a liquefaction reactor.

However, in the prior art, the preparation of the iron-based catalyst and the preparation of coal powder serving as a raw material for coal liquefaction are both split, i.e. the preparation of the catalyst and the preparation of the coal powder serving as the raw material are independent to form a system; meanwhile, the existing preparation of the iron catalyst usually adopts a liquid phase precipitation method, so that the process flow is long, the continuous operation difficulty of equipment is high, the water consumption is high, and the produced wastewater is more. Based on the reasons, the preparation of the catalyst is integrated into the preparation process of the raw material coal powder, and an integrated preparation method of the direct liquefaction catalyst and the raw material coal is researched to solve the problems that the preparation process of the catalyst in the prior art is long and complicated, high in water consumption and energy consumption, high in investment and production cost of direct coal liquefaction and the like.

Disclosure of Invention

The invention aims to provide a method for preparing a coal liquefaction raw material, which aims to solve the problems of poor mixing effect of a catalyst and pulverized coal and more water waste in the prior art.

The invention provides a method for preparing a coal liquefaction feedstock, the method comprising: conveying coal powder to a distributor, so that the coal powder is dispersed by the distributor and then falls into a cylindrical dipping absorber connected with the distributor; conveying a catalyst to a spray head inside the impregnation absorber for atomization so as to spray the catalyst onto the surface of the pulverized coal falling from the distributor and be absorbed by the pulverized coal; and conveying the coal dust mixed with the catalyst from the impregnation absorber into a dryer for drying and grinding, thereby preparing the coal liquefaction raw material with certain granularity and water content.

Further, the distributor is mechanical vibration distributor, mechanical vibration distributor include the distributing plate and with the vibrations mechanism that the distributing plate is connected, vibrations mechanism makes thereby the distributing plate vibrations make the buggy is in disperse on the distributing plate, the coal leakage structure has on the distributing plate.

Further, the coal leakage structure is a plurality of circular holes corresponding to the particle size of the pulverized coal, a grid shaped like a Chinese character 'jing' or an annular grid.

Furthermore, a plurality of spray gun layers are arranged in the dipping absorber along the axial direction of the dipping absorber, and one or more spray heads are distributed in each spray gun layer.

Furthermore, a plurality of spray heads in the same spray gun layer are uniformly distributed along the circumferential direction of the impregnation absorber, the spray heads in different spray gun layers are distributed along the circumferential direction of the impregnation absorber in a staggered manner, and the axial distance between the adjacent spray gun layers is 0.3-2 m.

Further, the catalyst is a solution containing a main active component iron element, and the concentration of the main active component iron element is 5 wt% to 15 wt%.

Further, the catalyst also comprises a secondary active component element, wherein the secondary active component element comprises one or more of nickel element, molybdenum element and tungsten element, and the content of the secondary active component element is 0-0.5 wt%.

Further, the catalyst is a slurry containing iron precipitate, and the slurry contains Fe (OH)₂And/or Fe (OH)₃And/or a slurry of hydrated iron oxides.

Further, hot air is blown into the dryer to dry the coal dust absorbing the catalyst, the inlet temperature of the hot air is 160-280 ℃, and the oxygen content in the hot air is less than 8%.

Further, the water content of the pulverized coal absorbing the catalyst is less than 30 wt%.

By applying the technical scheme of the invention, the preparation of the catalyst is matched with the preparation process of the raw material coal dust, the catalytic active component materials are directly immersed in all raw material coal in an atomization mode, and the coal liquefaction feeding coal dust with full-loaded active components is prepared after drying and grinding. The mode can ensure that the catalytic active components are distributed more uniformly on the surface of the coal powder, and almost all the coal powder can be in physical zero-distance contact with the catalytic active components, so that the conversion rate of coal and the yield of liquefied oil can be greatly improved. The solution or slurry of the catalytic active component is soaked on the surface of the coal powder in a spraying mode, so that the use amount of fresh water can be greatly saved, and no waste water is generated. Because a catalyst preparation device is not required to be independently arranged, the cost of the coal liquefaction device is greatly saved. The invention effectively solves the problem of poor mixing effect of the catalyst and the coal powder in the prior art.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic process flow diagram of the process for producing a coal-to-liquid feedstock of the present invention.

Fig. 2a to 2c are schematic views of three distribution plate distributions within a distributor according to the present invention, showing the distribution of circular holes, a grid in a well pattern and an annular grid, respectively.

Fig. 3a to 3c are top views of three spray gun arrangements in an immersion absorber according to the invention.

1. A crusher; 2. a pulverized coal metering tank; 3. a scraper conveyor; 4. a bucket elevator; 5. a distributor; 6. a dip absorber; 7. an iron material storage tank; 8. a metering pump; 9. a spray gun; 10. a scraper conveyor; 11. a ball milling dryer; 12. selecting a powder machine; 13. a conveying device; 14. a bag-type dust collector; 15. a storage hopper; 16. storing the raw materials in a warehouse; 17. a hot blast stove; 18. and a circulating fan.

Detailed Description

As shown in fig. 1, clean coal is crushed by a crusher 1 and then enters a pulverized coal metering tank 2, and after being metered, the clean coal is conveyed by a scraper conveyor 3 and a bucket elevator 4 to enter a distributor 5 (such as a mechanical vibration distributor), and under the vibration action, pulverized coal is distributed on a distribution plate and falls into a cylinder of a dipping absorber 6 below from holes on the distribution plate; meanwhile, the iron-containing material from the iron material storage tank 7 is pressurized by the metering pump 8 and then enters a spray head of a spray gun 9 arranged in the dipping absorber 6 for atomization, and the fog drops are contacted with the coal dust falling from the upper part and are absorbed by the coal dust. The pulverized coal absorbed with the iron-containing materials is discharged from a discharge valve at the lower part of the impregnation absorber 6, and enters a ball mill dryer 11 together with hot air from a hot blast stove 17 through a scraper conveyor 10 for drying and grinding. The material from the tail of the ball mill dryer enters a powder concentrator 12 to separate coarse powder from coarse powder, the separated coarse particle product returns to the inlet of the ball mill dryer 11 through a conveying device 13 to be ground and dried again, and the fine particle powder is brought into a bag-type dust collector 14 by gas to carry out gas-solid separation; powder products separated from the lower part of the bag-type dust remover enter a grinding storage hopper 15 and then are sent to a raw material storage bin 16 for storage, one part of gas above the bag-type dust remover is discharged, one part of gas passes through a circulating fan 18, and the other part of gas enters a hot blast stove 17 for heating and then circulates to a ball-milling dryer 11.

Based on the process flow as shown in fig. 1, the method for preparing a coal liquefaction feedstock of the present invention comprises the following steps: a, crushing directly liquefied raw material coal into coal powder with a certain granularity by a crusher; b, conveying the coal powder to a distributor 5, so that the coal powder falls into an impregnation absorber after being dispersed by the distributor 5; step c, delivering a catalyst (such as a material containing a catalytic active component) to a spray head inside the dipping absorber for atomization so as to spray on the surface of the pulverized coal falling from the distributor 5 and be absorbed by the pulverized coal; and d, conveying the coal powder mixed with the catalyst from the impregnation absorber (such as from the bottom of the impregnation absorber) into a dryer for drying and grinding, so as to prepare the coal liquefaction raw material with certain granularity and moisture. By the process, the catalytic active components are distributed more uniformly on the surface of the coal powder, almost all the coal powder can be in physical zero-distance contact with the catalytic active components, and therefore the conversion rate of coal and the yield of liquefied oil can be greatly improved.

In step a, the directly liquefied raw material coal refers to washed clean coal after washing, and is preferably young bituminous coal or lignite which has a short coal-forming period and is more easily liquefied.

In step a, the pulverized coal with a certain particle size refers to pulverized coal with a particle size smaller than 10mm, preferably pulverized coal with a particle size smaller than 5mm, and more preferably pulverized coal with a particle size smaller than 3mm, which is screened after raw material coal is crushed by a crusher. The smaller the granularity of the pulverized coal after crushing is, the larger the surface area is, the more sufficient the diffusion of the catalytic active components on the surface is, the more uniform the distribution is, the possibility of the catalytic active components aggregating to form clusters can be reduced, and the coal liquefaction efficiency can be improved.

In step b, the distributor 5 is preferably a mechanical vibration distributor; the mechanical vibration distributor comprises a distribution plate and a vibration mechanism, wherein the distribution plate is provided with a coal leakage structure, such as a plurality of circular holes which correspond to the particle size of crushed coal and can be made into grid holes in the shape of a Chinese character 'jing', or annular grid holes; the size of the holes can allow the largest coal dust to fall, and the optimal size is 1-2 mm larger than the crushed particle size of the coal dust. Under the action of vibration, the pulverized coal can be dispersed on several forms of distribution plates, such as circular holes, grid in the shape of Chinese character jing, circular grid and the like, which are distributed on the distribution plate, and can uniformly fall into the cylinder body of the impregnation absorber through the holes or grids on the distribution plate. The coal powder contacts with the catalytic active component solution or slurry of the atomized catalyst and is gradually absorbed in the falling process, so that the uniform load and distribution of the catalytic active components of the catalyst on the coal powder are realized.

In step b, the immersion absorber means a cylindrical barrel connected to the upper sparger 5; the spray guns in the same layer are preferably uniformly distributed along the circumferential direction of the barrel in the overlooking direction, the spray guns in the upper layer and the lower layer of spray guns are staggered along the circumferential direction, and the axial distance between every two adjacent spray gun layers is preferably 0.3m to 2 m; the spray gun layer and the spray head arranged in this way can more uniformly realize the distribution of the catalytic active components of the catalyst on the pulverized coal.

In step c, the spraying direction of the spray head is downward spraying along the axial direction of the cylinder.

In step c, the catalyst (i.e., theMaterial containing a catalytically active component) means a solution or a slurry containing an iron precipitate as a main active component, preferably a material containing the main active component at a concentration of 5 to 15 wt%; the material can also contain one or more minor active ingredients such as trace nickel, molybdenum, tungsten elements and the like, preferably, the minor active ingredient elements in the material are corresponding soluble salts, and preferably, the content of the minor active ingredient elements in the material is 0 to 0.5 wt%. The iron-containing solution in the main active component is preferably a ferrous sulfate and/or ferric sulfate solution; the iron-containing slurry preferably contains Fe (OH)₂And/or Fe (OH)₃And/or a slurry of hydrated iron oxides.

The dispersibility of the iron element as the main active ingredient is one of important influencing factors, and the concentration of the iron element in the solution or slurry is required to be 5 wt% to 15 wt% in the invention, because the concentration is too high, which is not favorable for atomization and dispersion, and the iron element is unevenly distributed on the surface of coal, and the concentration is too low, which makes the loading amount of the main active ingredient not reach the requirement. The addition of a very small amount of secondary active components such as nickel, molybdenum and tungsten elements with excellent hydrogenation performance is an effective means for improving the weak hydrogen activation capability of iron, but the elements are relatively expensive, and the cost is increased if the content of the elements is too high.

In the step d, blowing hot air into the dryer 11 to dry the coal dust absorbing the catalytic active components, wherein the inlet temperature of the hot air is 160-280 ℃, and the oxygen content in the hot air is required to be less than 8%; if the temperature of the hot air is too low, the water content of the product is too high, and if the temperature of the hot air is too high, the activity of active species impregnated on the product can be decomposed, so that the activity is reduced. The oxygen content in the hot air is less than 8% to avoid explosion risk.

In step d, the dryer 11 is a dryer capable of simultaneously grinding/crushing and drying the product, preferably a ball mill dryer, which has a strong grinding effect on the catalyst while drying the product, so that the yield of the product is higher.

In step d, the desired water content of the absorbed coal fines containing catalytically active components is less than 30 wt.%, preferably less than 25 wt.%. In the step d, the granularity of the coal liquefaction raw material is required to be less than 80um, the loading capacity of the main active component iron element is 0.5 wt% to 1.5 wt%, and the water content is less than 1 wt%. In step d, such coal liquefaction raw materials can be mixed with the coal liquefaction circulating solvent to directly perform the coal direct liquefaction reaction.

The production process according to the method of the invention is followed by the integrated preparation of catalyst and feed coal on a 100kg/h scale unit, with a certain bituminous coal having a particle size of less than 30mm after washing. The analysis is shown in Table 1.

TABLE 1 Industrial and elemental analysis

Example 1

Preparing a hydrated iron oxide slurry by a precipitation-air oxidation process: adding ammonia water into the ferrous sulfate solution, precipitating ferrous iron in advance, and then introducing compressed air for oxidation to prepare hydrated ferric oxide slurry, wherein the concentration of Fe in the hydrated ferric oxide slurry is 10 wt%.

The adopted raw material coal is clean coal, the coal is conveyed into a crusher to be crushed to be less than 3mm, the crushed clean coal enters a distributor 5 through a scraper conveyor and a scraper elevator, and the conveying speed is 100 kg/h; the distributor 5 is a circular distribution plate as shown in fig. 2a, and the coal is dispersed on the distribution plate and then falls from the holes into the cylinder of the impregnation absorber.

Conveying the hydrated iron oxide slurry to a spray gun nozzle in the impregnation absorber by a metering pump for atomization, wherein the feeding speed of the hydrated iron oxide slurry is 10 kg/h. The two-layer spray gun assembly shown in FIG. 3a was used with a nozzle diameter of 1 mm.

After the coal in the cylinder of the dipping absorber absorbs the hydrated ferric oxide slurry dipped and atomized at the same time, the hydrated ferric oxide slurry is continuously conveyed to a ball mill dryer; hot air is introduced into the drier, and the inlet temperature of the hot air is 200 ℃. The product (i.e., coal liquefaction feedstock, i.e., catalyst and feedstock coal integrated feedstock) obtained at the end of the preparation is numbered # 1.

Example 2

The size of the coal crushed by the crusher was changed to less than 5mm, and the product obtained was numbered 2# under the same conditions as in example 1.

Example 3

The size of the coal crushed by the crusher was changed to less than 10mm, and the product was numbered # 3 under the same conditions as in example 1.

Example 4

The concentration of Fe in the resultant hydrous iron oxide slurry was changed to 15 wt%, and a cross-hatched distribution plate as shown in FIG. 2b was used in the distributor 5, and a three-layer spray gun assembly as shown in FIG. 3b was used, and the other conditions were the same as in example 1, to obtain a product No. 4.

Example 5

The Fe concentration of the resultant hydrated iron oxide was changed to 5 wt%, and a ring-shaped distribution plate as shown in FIG. 2c was used in the distributor 5, a two-layer lance combination as shown in FIG. 3c was used, and the other conditions were the same as in example 1, and the product was manufactured with a number of # 5.

Example 6

The preparation method and concentration of the iron-containing slurry are changed, namely, ammonia water is added into the ferric sulfate solution to prepare the ferric hydroxide slurry, the concentration of Fe in the ferric hydroxide slurry is 8 wt%, other conditions are the same as those in the example 1, and the serial number of the prepared product is No. 6.

Example 7

The iron-containing material was changed to ferric sulfate solution, the concentration of Fe in the solution was 12 wt%, the other conditions were the same as in example 1, and the product was numbered 7 #.

Example 8

Ammonium molybdate was added to the hydrous iron oxide slurry so that the slurry simultaneously contained Mo in a concentration of 0.2 wt%, and the other conditions were the same as in example 1, to obtain a product No. 8.

Example 9

Ammonium molybdate and cobalt sulfate were added to the hydrous iron oxide slurry so that the slurry contained 0.2 wt% of Mo and 0.3 wt% of cobalt at the same time, under the same conditions as in example 1, and the product was numbered # 9.

Example 10

The temperature of hot air entering the ball mill dryer was changed to 160 degrees, and the product was numbered 10# as in example 1.

Example 11

The temperature of hot air entering the ball mill dryer was changed to 280 degrees, other conditions were the same as in example 1, and the product number was 11 #.

Comparative example 1

Preparing a coal powder loaded FeOOH catalyst by adopting a liquid-phase precipitation oxidation method: weighing 180g of ferrous sulfate heptahydrate, adding the ferrous sulfate heptahydrate into 1000g of deionized water to prepare a ferrous sulfate solution, adding 500g of the coal with the granularity within 150 mu m, and fully and uniformly stirring; 1000g of an aqueous ammonia solution having a concentration of 2.0 wt.% was prepared. Feeding a mixed solution of ferrous sulfate and coal powder and an ammonia solution in a parallel flow manner to enable the ferrous to be subjected to a precipitation reaction, and then introducing air to react for 1.5 hours; and centrifugally separating the mixed slurry to obtain a filter cake, adding deionized water into the filter cake for pulping and washing, drying the washed filter cake in a nitrogen drying oven at 110 ℃ for 12 hours, and grinding the solid to be below 80 mu m after drying to obtain the coal powder supported FeOOH powder catalyst. Labeled as contrast agent 1.

Evaluation of catalyst Performance

The products of the above examples and the catalysts prepared in the comparative examples were subjected to the test in a coal liquefaction autoclave.

The coal liquefaction test conditions for the products in the examples are as follows: respectively calculating and weighing the products in the above embodiments based on 28g of total dry coal, adding the products into a 500mL autoclave, and then adding 42g of coal liquefaction cycle solvent oil and 0.32g of sulfur powder; and (3) after the kettle is closed, performing three times of hydrogen replacement, setting the initial pressure of the reaction cold hydrogen of the high-pressure kettle to be 10MPa, heating to 455 ℃, keeping the temperature for 1h, after the reaction is finished, rapidly cooling the reaction system, taking a gas sample to measure the composition of the gas sample, collecting liquid and solid phases after the reaction, performing Soxhlet extraction for 48h by using normal hexane and tetrahydrofuran respectively, burning ash on the extraction residues, and calculating to obtain the data such as coal conversion rate, hydrogen consumption, gas yield, water yield, asphalt yield, oil yield and the like.

The coal liquefaction test conditions of the catalyst prepared in the comparative example 1 are the same as the reaction conditions of the examples, and the difference is that raw material coal dust needs to be additionally added, and the main principle is as follows: the total amount of coal dust added into the autoclave was 28g (consistent with the coal type and coal amount used in the examples), the catalyst was added at a weight ratio of Fe/total dry coal of 1%, and the additional amount of coal dust was 28g minus the amount of coal dust in the catalyst; similarly, the adding amount of the coal liquefaction circulating solvent is 42g, and the adding amount of the sulfur powder is 0.32 g.

All coal liquefaction test results are shown in table 2.

TABLE 2 catalyst composition and coal liquefaction results

As can be seen from the results of direct coal liquefaction in the autoclave shown in Table 2, the conversion rate of coal and the yield of liquefied oil of the raw material prepared by the process unit of the integrated preparation method of the catalyst and the raw material are both superior to those of the contrast agent, and especially, the yield of key product oil is greatly improved, so that the direct coal liquefaction efficiency and the economical efficiency are greatly improved.

Meanwhile, the method for preparing the coal liquefaction raw material provided by the application integrates the preparation of the catalyst into the preparation process of the raw material coal dust on the premise of not excessively complicating the preparation process of the raw material coal dust, so that a catalyst preparation device is not required to be independently arranged on a direct coal liquefaction production line, the overall investment of direct coal liquefaction is reduced, and the water consumption and the energy consumption in the production process can be greatly reduced.

Therefore, the method for preparing the coal liquefaction raw material has great application value, and can rapidly generate great economic benefit in the field of coal chemical industry.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a coal liquefaction feedstock, the method comprising:

conveying coal powder to a distributor (5) so that the coal powder is dispersed by the distributor and then falls into a cylindrical dipping absorber (6) connected with the distributor;

a spray nozzle (9) for conveying the catalyst to the interior of the impregnation absorber (6) is atomized to be sprayed on the surface of the pulverized coal falling from the distributor (5) and absorbed by the pulverized coal;

conveying the coal dust mixed with the catalyst from the impregnation absorber (6) into a dryer (11) for drying and grinding to prepare the coal liquefaction raw material with certain particle size and water content,

wherein the sparger (5) is arranged at the top of the cylindrical impregnation absorber (6) and is in communication with the cylindrical impregnation absorber (6), and the cylindrical impregnation absorber (6) is arranged vertically such that the coal dust from the sparger (5) falls within the cylindrical impregnation absorber (6) by means of gravity.

2. The method according to claim 1, wherein the distributor is a mechanical vibration distributor, the mechanical vibration distributor comprises a distribution plate and a vibration mechanism connected with the distribution plate, the vibration mechanism vibrates the distribution plate so that the pulverized coal is dispersed on the distribution plate, and the distribution plate is provided with a coal leakage structure.

3. The method according to claim 2, wherein the coal leakage structure is a plurality of circular holes, a "well" -shaped grid or an annular grid corresponding to the particle size of the pulverized coal.

4. The method according to claim 1, characterized in that a plurality of spray gun layers are arranged in the immersion absorber in the axial direction of the immersion absorber, in each of which spray gun layers one or more spray heads are distributed.

5. The method according to claim 4, wherein the spray heads in the same spray gun layer are uniformly distributed in the circumferential direction of the impregnation absorber, the spray heads in different spray gun layers are staggered in the circumferential direction of the impregnation absorber, and the axial distance between adjacent spray gun layers is 0.3m to 2 m.

6. The method of claim 1, wherein the catalyst is a solution comprising a major active ingredient iron element at a concentration of 5 wt% to 15 wt%.

7. The method of claim 1 or 6, wherein the catalyst further comprises a secondary active component element comprising one or more of nickel, molybdenum and tungsten, and the secondary active component element is present in an amount of 0 to 0.5 wt%.

8. The method of claim 1, wherein the catalyst is a slurry of iron-containing precipitates, the slurry comprising Fe (OH)₂And/or Fe (OH)₃And/or a slurry of hydrated iron oxides.

9. The method according to claim 1, wherein hot air is blown into the dryer to dry the pulverized coal absorbed with the catalyst, an inlet temperature of the hot air is 160 to 280 ℃, and an oxygen content of the hot air is less than 8%.

10. The method of claim 1, wherein the water content of the coal fines absorbed by the catalyst is less than 30 wt%.