Direct coal liquefaction residue solvent extraction deliming method, refined asphalt and application

Abstract

The invention discloses a direct coal liquefaction residue solvent extraction deliming method, refined asphalt and application, and relates to the technical field of solid waste resource treatment. According to the method, process conditions and process parameters are reasonably controlled, the thermal dissolution effect of an extraction agent and the liquefied residues is improved, a scale inhibitor composed of a multi-element alkyl organic matter, an auxiliary and coking washing oil is mixed with the extraction agent, then the ground liquefied residues are added into a material obtained through mixing, and the extraction agent and the liquefied residues are mixed uniformly. The slurry is prepared by controlling the stirring speed, the reaction temperature and the like; due to the addition of the scale inhibitor, the concentration of the residue extraction liquid is improved, and the treatment capacity and efficiency are enhanced; and a filter used for precision filtration adopts a stainless steel metal sintered filter element, so that the filter is resistant to higher temperature and pressure, the service life can be prolonged, and the stripping of viscous materials such as asphaltene in the liquefied residues is facilitated. The ultralow-ash refined asphalt prepared by the method can be used as a high-quality raw material of a high-end carbon material.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste resource treatment, and in particular to a method for deashing by solvent extraction of coal direct liquefaction residue, refined asphalt and application thereof. Background Art

[0002] Energy endowment and economic development determine that China is the world's largest coal producer and consumer. At present, coal accounts for a high proportion in my country's energy consumption structure, while crude oil still has a high degree of external dependence. Based on the advantages of coal endowment, we vigorously develop modern coal chemical industry and are committed to the efficient conversion of coal into oil and gas. Coal direct liquefaction technology is extremely prominent in the field of coal-to-oil and has extremely important energy strategic significance.

[0003] my country is the only country in the world that has mastered the key technology of direct coal liquefaction at the million-ton level, but there has been no large-scale breakthrough in the efficient resource utilization technology of coal liquefaction residue. Coal direct liquefaction technology produces gasoline and diesel, by-product gas, water and coal liquefaction residue. The output of coal liquefaction residue is generally 30% of the raw coal. It has the characteristics of high carbon, high ash and high sulfur, and is composed of heavy oil, liquefied intermediates, unconverted coal and minerals. Traditional gasification, coking and combustion do not reflect the high added value utilization potential of liquefied residue. The preparation of high-end carbon materials from coal liquefaction residue is a hot topic in the current research field of coal direct liquefaction technology. The key to the realization of this process lies in the efficient and deep deashing of the residue. Due to the characteristics of the residue such as very small solid particle size, very high viscosity, and small density difference between the liquid phase and the granular solid, the difficulty of removing inorganic ash in liquefied asphalt is increased.

[0004] Therefore, developing efficient deep deashing technology based on the fluid characteristics and physical property differences of liquefied asphalt in the extraction system, breaking through the technical bottleneck of preparing high-end carbon materials from liquefied asphalt, and completing the development of the entire process chain are also important components of coal liquefaction process technology development and industrial chain extension. Technological breakthroughs will promote the rapid development of direct liquefaction technology, boost industry transformation and upgrading, and play a significant supporting and leading role. Summary of the invention

[0005] One of the purposes of the present invention is to provide a method for deashing coal direct liquefaction residue by solvent extraction, which improves the processing capacity, stability and continuity of the liquefaction residue extraction deashing refining process.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for deashing coal direct liquefaction residue by solvent extraction, comprising the following steps in sequence:

[0008] (1) adding the extractant and the scale inhibitor into the preparation tank in sequence, stirring and heating them; when the material temperature in the preparation tank reaches 60° C., adding the liquefied residue after grinding into the preparation tank to start slurrying; after the liquefied residue is added, N2 is introduced into the preparation tank, and the pressure is adjusted to 0.1-0.3 MPa and stirring is maintained; when the temperature of the preparation tank reaches 80-160° C., the temperature is kept constant for a period of time; the mass of the scale inhibitor accounts for 0.05-0.2% of the mass percentage of the extractant; the mass ratio of the extractant to the liquefied residue after grinding is 1-3:1;

[0009] The scale inhibitor is composed of the following components in terms of mass percentage:

[0010] Polyhydric hydrocarbon organic matter 20-30%, additive 10-20%, the balance is coking wash oil;

[0011] (2) After a period of constant temperature, the obtained slurry is pumped into a metering tank at one time, and the slurry is stably pumped into a centrifuge for centrifugal separation through the metering tank;

[0012] (3) The extract obtained by centrifugal separation enters a storage tank connected to the centrifuge, and the extract is sent from the storage tank to a filter for precision filtration. The filter element used for precision filtration is made of sintered stainless steel mesh material, and the pore size of the filter hole is 0.5 to 5 μm;

[0013] (4) The filtrate obtained after the precision filtration in step (3) enters a flash tower, and the extractant at the top of the flash tower is recycled, and the bottom of the flash tower is deashed and refined asphalt;

[0014] (5) The filter residue obtained by centrifugal separation in step (3) and the filter residue obtained after precision filtration in step (4) are passed into a dryer for drying and recycling.

[0015] In the above-mentioned method for deashing coal direct liquefaction residue by solvent extraction, in step (1), the extractant is coking wash oil; the polyalkyl organic matter is alkylphenol, alkylphenol polyoxyethylene ether, polyether polyol or polyol fatty acid ester, and the polyalkyl organic matter inhibits the deposition of asphaltene by adsorbing on the surface of the medium to form a protective layer of hydrocarbon derivatives; and the auxiliary agent is a surfactant.

[0016] In the above-mentioned method for deashing coal direct liquefaction residue by solvent extraction, the surfactant is selected from one or more of sodium dodecyl sulfonate, dodecylbenzene sulfonic acid, benzoic acid, and dodecylphenol.

[0017] In the above-mentioned method for deashing coal direct liquefaction residue by solvent extraction, in step (1), the particle size of the liquefied residue after grinding is less than 2 mm; the heating method of the configuration tank is oil bath heating, steam heating or electric heating; the stirring rate of the extractant and scale inhibitor in the configuration tank is 80 to 200 rpm, and the stirring time is 10 to 45 min; after adjusting the pressure to 0.1 to 0.3 MPa, the stirring rate is adjusted to 100 to 250 rpm; and the constant temperature time is 30 to 90 min.

[0018] In the above-mentioned method for deashing by solvent extraction of coal direct liquefaction residue, in step (2), a horizontal screw centrifuge is used for centrifugal separation, the separation linear speed of the horizontal screw centrifuge is 60-120 m / s, and the temperature inside the centrifuge is 70-120°C.

[0019] In the above-mentioned method for deashing coal direct liquefaction residue by solvent extraction, in step (3), the solid content of the extract obtained by centrifugal separation is <1-2%; the filter has a maximum pressure resistance of 2.0 MPa and a maximum temperature resistance of 260°C.

[0020] In the above-mentioned method for deashing by solvent extraction of coal direct liquefaction residue, in step (3), the specific steps of precision filtration are:

[0021] Step 1: Feeding - filtration - positive blowing: preheat the filter to 80-120℃ and keep it constant. The extract in the centrifuge is continuously pumped into the filter through the inlet. When the pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding; at this time, start N2 positive blowing mode, positive blowing pressure ≤ 3kgf / cm 2 , wait for the outlet pressure difference to be less than 0.5kgf / cm 2 Stop N2 purging, and the extract in the centrifuge is continuously pumped into the filter again. The pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding and start the positive blowing mode again. When the pressure difference between feed-filter-filter outlet is greater than 2.5kgf / cm 2 - Positive blowing - outlet pressure difference is less than 0.5kgf / cm 2 Repeat the operation cycle in this mode until the pressure difference between the inlet and outlet of the filter after positive blowing is still greater than 2.5kgf / cm 2 This mode is terminated and the backflush mode of step 2 is entered;

[0022] Step 2: Backflush: Turn on N2 backflush, backflush gas pressure ≤ 5kgf / cm 2 After a period of time, stop N2 backflushing, the filter residue on the surface of the filter element is blown to the bottom of the filter by nitrogen, the filter element restores the filtrate flux, and enters step 1. The filter residue at the bottom of the filter is discharged regularly.

[0023] The above-mentioned method for deashing coal direct liquefaction residue by solvent extraction is characterized in that: in step (5), the drying temperature of the dryer is 200-300°C and the drying time is 0.5-3h.

[0024] Another object of the present invention is to provide a refined asphalt obtained by the above-mentioned coal direct liquefaction residue solvent extraction deashing method, wherein the ash content of the deashed refined asphalt is less than 200 ppm and the quinoline insoluble matter content is less than 0.05%.

[0025] Another object of the present invention is to provide an application of the above-mentioned refined asphalt, wherein the application is to use the refined asphalt as a raw material for high-performance asphalt-based carbon fibers, foamed carbon lithium-ion battery negative electrode materials, or high-end carbon materials such as needle coke.

[0026] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0027] (1) The present invention aims at the unique structural composition of the liquefied residue and the physical properties and solubility of the mixed system with the extractant, mixes a scale inhibitor composed of a polyhydrocarbon-based organic matter, an additive and coking washing oil with the extractant, heats the scale inhibitor and the extractant to 60°C, and then adds the ground liquefied residue thereto, and prepares a slurry by controlling the stirring speed, reaction temperature, etc. The addition of the scale inhibitor increases the concentration of the residue extract and enhances the processing capacity and efficiency. In addition, the filter element of the filter used for precision filtration of the present invention is made of sintered stainless steel mesh material. The use of a stainless steel sintered filter element can improve the physical and chemical properties of the filter element surface, greatly improving the continuous operation period and stability of the process for preparing ultra-low ash (<200ppm) refined asphalt from liquefied residue.

[0028] (2) The method of the present invention is beneficial to improving the thermal dissolution efficiency of the liquefied residue, reducing the viscosity of the extraction system, improving the efficiency of traditional filtration separation, reducing the loss of the extractant, and improving the recovery efficiency of the extractant, by regulating the specific process parameters of the liquefied residue, the extractant and the scale inhibitor, which is beneficial to extending the continuous and stable operation period of the liquefied residue extraction deashing and refining process.

[0029] (3) Based on the high viscosity of asphaltene in the liquefied residue extraction suspension system, the scale inhibitor is introduced into the extraction system composed of liquefied residue and coking wash oil. This can increase the concentration of the liquefied residue extract, reduce the viscosity of the residue slurry system, improve the flow properties of the residue slurry system, help remove the viscous asphaltene on the pipe wall, facilitate the smooth flow of the pipeline for transporting the residue slurry system, extend the cleaning cycle of the residue transportation pipeline, and improve the processing capacity, stability and continuity of the liquefied residue extraction deashing and refining process.

[0030] (4) The use of stainless steel sintered metal filter elements is conducive to the stripping of high-viscosity substances such as asphaltene in the liquefied residue. In addition, the stainless steel sintered metal filter elements have multiple functions of enhancing the wear resistance, corrosion resistance and thermal stability of the filter elements, significantly improving the efficiency and economic performance of the liquefied residue extraction deashing and refining process technology.

[0031] In summary, the present invention provides a method for deashing by solvent extraction of direct coal liquefaction residue, refined asphalt and application, introduces a dispersed scale inhibitor into a high-viscosity extraction system composed of liquefied residue and wash oil, adopts a stainless steel sintered filter element, and selects a process technology for deashing and refining liquefied residue by coupling centrifugal separation and precision filtration. It has the advantages of high degree of automation, large processing capacity, safe, closed, stable and long-term operation, and is suitable for special working conditions such as high ash content in coal liquefaction residue, high viscosity system for extraction of coal liquefaction residue, ultra-high filtration accuracy and high-temperature process environment. The prepared ultra-low ash refined asphalt can be used as a high-quality raw material for high-end carbon materials (high-performance asphalt-based carbon fiber, foamed carbon, lithium-ion battery negative electrode material and needle coke, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings:

[0033] Figure 1 This is a high-resolution photo of the liquefied residue of the present invention;

[0034] Figure 2 A high-definition photo of the refined asphalt obtained by the method of the present invention;

[0035] Figure 3 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0036] The present invention proposes a method for deashing by solvent extraction of coal direct liquefaction residue, refined asphalt and application. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is further described below in conjunction with specific embodiments.

[0037] The raw materials described in the present invention can be obtained through commercial channels. Figure 1 As shown, the raw material liquefaction residue of the present invention has an appearance similar to asphalt, which is a black flaky solid, brittle and easy to break. The residue has a high sulfur content, which is caused by the use of sulfur additives in the liquefaction process, resulting in sulfur enrichment in the liquefied residue. The sulfur in the residue is mostly in the form of inorganic sulfur. The nitrogen content of the residue is 0.82%, and the ash content is 15.52%, which is mainly composed of minerals in coal and residual liquefaction catalyst. Figure 2 As shown, the ash content of the refined product of liquefied residue deashing is less than 200ppm, the QI is less than 500ppm, the sulfur content is less than 100ppm, the extraction agent recovery rate can reach 96%, and the refined asphalt yield can reach 96%.

[0038] The main technical concept of the present invention is: the use of scale inhibitors is conducive to reducing the viscosity of the extraction system, improving the agent-slag ratio, and extending the pipeline cleaning cycle; the use of stainless steel metal sintered filter elements effectively reduces the attachment of extracts on the filter element surface, which is conducive to backwashing to quickly restore the filtration efficiency; suitable hot melt-filtration process parameters are conducive to the dissolution of liquefied residues and the improvement of separation efficiency. Scale inhibitors, stainless steel sintered filter elements, and suitable process parameters, combined with horizontal screw centrifugation-precision filtration coupling technology, can achieve deep deashing of liquefied residue extraction and achieve stable long-term operation of continuous processes.

[0039] The raw material liquefaction residue, extractant and scale inhibitor required by the present invention are prepared, wherein the liquefaction residue is ground to a particle size of <2 mm for standby use, so as to shorten the dissolution time and improve the dissolution efficiency; the extractant is selected from cheap and readily available coking wash oil; the scale inhibitor is composed of the following raw material components in terms of mass percentage: 20-30% of polyalkyl organic matter, 10-20% of auxiliary agent, and the remainder of coking wash oil.

[0040] The polyhydric organic matter is preferably selected from alkylphenol, alkylphenol polyoxyethylene ether, polyether polyol or polyol fatty acid ester, etc. These polyhydric organic matter contain multiple hydroxyl groups, have strong positive charge, strong adsorption capacity, and are preferentially adsorbed on the surface of the medium to form a protective layer of hydroxyl derivatives, thereby inhibiting the deposition of asphaltene.

[0041] The above-mentioned auxiliary agent is preferably selected from one or more of sodium dodecyl sulfate, dodecylbenzene sulfonic acid, benzoic acid, and dodecylphenol. Organic acid provides lipophilic groups to ensure that asphaltene is better dissolved and dispersed in the liquefied residue washing oil extraction system. At the same time, the presence of lipophilic groups and chains in the molecular structure can be adsorbed on lipophilic surfaces such as asphaltene to hinder the aggregation, bonding, and adhesion of lipophilic solid phases, thereby reducing spatial friction and spatial structural force, and then reducing viscosity and shear force. In addition, the auxiliary agent is actually a surfactant that can reduce interfacial surface tension, so that the liquefied residue and washing oil form a stable dispersion system, effectively improving dispersibility and stability.

[0042] like Figure 3 As shown, the present invention is a method for deashing by solvent extraction of coal direct liquefaction residue, and the required system mainly includes a configuration tank, a metering tank, a centrifuge, a storage tank, a filter, a flash tower and a dryer. The configuration tank, the metering pump and the centrifuge are connected in sequence, the extraction liquid outlet of the centrifuge is connected to the storage tank, the filter residue outlet of the centrifuge is connected to the dryer, the filter adopts a maximum pressure resistance of 2.0MPa and a maximum temperature resistance of 260°C, the filter element adopts a sintered stainless steel mesh material, and the filter pore size is 0.5-5μm. The filter residue outlet of the filter is connected to the dryer, and the filtrate outlet of the filter is connected to the flash tower.

[0043] The method of the present invention specifically comprises the following steps:

[0044] Step 1: Thermal Dissolution

[0045] The extractant is added into a preparation tank, the outer shell of which is heated by oil bath, steam or electricity. The preparation tank is provided with a stirrer. The stirrer is turned on during the adding of the extractant, the stirring rate is 80-200 rpm, and the mass of the scale inhibitor accounts for 0.05-0.2% of the mass percentage of the extractant. The stirring time is 10-45 min, and the tank body of the preparation tank is heated to 80-160°C. When the temperature of the solvent in the preparation tank reaches 60°C, the residue powder (mass of the extractant / mass of the residue = 1-3:1) is added to start slurrying. After the addition of the residue powder, N2 is introduced, the pressure is adjusted to 0.1-0.3 MPa, and the stirring rate is adjusted to 100-250 rpm. When the temperature of the preparation tank reaches 80-160°C, the slurry is pumped into the metering tank once after the constant temperature is maintained for 30-90 min, and the pump at the bottom of the metering tank continuously and stably pumps the slurry into the centrifuge.

[0046] Step 2: Centrifugal separation

[0047] The present invention preferably uses a decanter centrifuge for centrifugal separation. The decanter centrifuge is a continuous feeding and discharging device, which is very suitable for large-scale, long-term continuous operation. Increasing the linear velocity and separation temperature of the decanter centrifuge can improve the separation efficiency of the extract and the residue, which is beneficial to reducing the solid content in the extract. However, too high a linear velocity and separation temperature of the decanter centrifuge will increase energy consumption. The present invention preferably has a linear velocity of 60 to 120 m / s, an internal temperature of 70 to 120°C in the centrifuge, and a solid content of <1 to 2% in the extract.

[0048] Step 3: Precision Filtration

[0049] (1) Feeding - filtration - positive blowing: The filter is preheated to 80-120℃ and kept constant. The extract in the centrifugal separation is continuously pumped into the filter. When the pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding, start N2 positive blowing (nitrogen flow direction is consistent with the filtering direction) mode, the positive blowing pressure does not exceed 3kgf / cm 2 , after 5 minutes, the outlet pressure difference is less than 0.5kgf / cm 2 Stop N2 purging, and the extract in the centrifuge is continuously pumped into the filter again. The pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding and start the positive blowing mode again. When the pressure difference between feed-filter-filter outlet is greater than 2.5kgf / cm 2 - Positive blowing - outlet pressure difference is less than 0.5kgf / cm 2 Repeat the operation cycle in this mode until the pressure difference between the inlet and outlet of the filter after positive blowing is still greater than 2.5kgf / cm 2This mode is terminated and the backflush mode is entered.

[0050] (2) Backflush: Turn on N2 backflush (a purge method in which the nitrogen gas flows in the opposite direction of the filtration direction, aiming to blow off the filter cake attached to the surface of the filter element and restore the filtration flux). The backflush gas pressure does not exceed 5kgf / cm 2 After 10 minutes, stop N2 backflushing, and the filter residue on the surface of the filter element is blown to the bottom of the filter by nitrogen. The filter element restores the filtrate flux and enters step (1). The filter residue at the bottom of the filter is discharged regularly.

[0051] Step 4: Recover the extractant from the extract by flash evaporation under reduced pressure

[0052] The filtrate in the filter enters the flash tower, the top of the tower is the extractant, which can be reused for thermal dissolution with the residue, and the bottom of the tower is the deashed refined asphalt, with an ash content of less than 200ppm and a QI (quinoline insoluble matter) content of less than 0.05%. Figure 2 It is mainly used as the raw material for high-end carbon materials such as high-performance asphalt-based carbon fiber, foamed carbon, negative electrode materials for lithium-ion batteries and needle coke.

[0053] Step 5: Dry the filter residue to recover the extractant in the residue

[0054] The centrifugal filter residue and the regularly discharged filter residue contain 20-30% of the extractant. The residual extractant in the filter residue is recovered by heating and drying (such as film drying, vacuum drying or steam stripping). The drying temperature is 200-300°C and the drying time is 0.5-3h. The recovered extractant can be mixed with the extractant recovered by vacuum distillation and reused for pulping with the residue. The dry filter residue can be used as fuel or gasification raw material.

[0055] The present invention is described in detail below through specific examples. The properties of the raw material liquefaction residue in the examples are shown in Table 1.

[0056] Table 1 Analysis of properties of liquefied residue

[0057] project <![CDATA[Q net,ar / Kcal / kg]]> 6367 <![CDATA[M t / %]]> Not detected <![CDATA[A d / %]]> 15.52 <![CDATA[V daf / %]]> 41.40 <![CDATA[S t,d / %]]> 2.02 <![CDATA[N ,d / %]]> 0.82 Quinoline insoluble matter (QI) / % 32.32

[0058] The present invention is further described in conjunction with Examples 1 to 4 and Comparative Examples 1 to 4. From the Examples shown in Table 2 and the Comparative Examples shown in Table 3, it can be learned that different process parameters, ratios, etc. affect the physical properties of refined asphalt.

[0059] Table 2 Analysis of properties of refined asphalt products in Example 1 to Example 4

[0060]

[0061] Table 3 Analysis of properties of asphalt products in Comparative Examples 1 to 4

[0062]

[0063] Parts not described in the present invention can be implemented by those skilled in the art by referring to the existing technology.

[0064] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments should fall within the scope of protection of the claims of the present application.

Claims

1. A method for deashing coal direct liquefaction residue by solvent extraction, characterized in that: The following steps are included in sequence: (1) adding the extractant and the scale inhibitor into the preparation tank in sequence, stirring and heating them; when the material temperature in the preparation tank reaches 60° C., adding the liquefied residue after grinding into the preparation tank to start slurrying; after the liquefied residue is added, N2 is introduced into the preparation tank, and the pressure is adjusted to 0.1-0.3 MPa and stirring is maintained; when the temperature of the preparation tank reaches 80-160° C., the temperature is kept constant for a period of time; the mass of the scale inhibitor accounts for 0.05-0.2% of the mass percentage of the extractant; the mass ratio of the extractant to the liquefied residue after grinding is 1-3:1; The scale inhibitor is composed of the following components in terms of mass percentage: Polyhydric hydrocarbon organic matter 20-30%, additive 10-20%, the balance is coking wash oil; (2) After a period of constant temperature, the obtained slurry is pumped into a metering tank at one time, and the slurry is stably pumped into a centrifuge for centrifugal separation through the metering tank; (3) The extract obtained by centrifugal separation enters a storage tank connected to the centrifuge, and the extract is sent from the storage tank to a filter for precision filtration. The filter element used for precision filtration is made of sintered stainless steel mesh material, and the pore size of the filter hole is 0.5 to 5 μm; (4) The filtrate obtained after the precision filtration in step (3) enters a flash tower, and the extractant at the top of the flash tower is recycled, and the bottom of the flash tower is deashed and refined asphalt; (5) The filter residue obtained by centrifugal separation in step (3) and the filter residue obtained after precision filtration in step (4) are passed into a dryer for drying and recycling.

2. A method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (1), the extractant is coking wash oil; the polyalkyl organic matter is alkylphenol, alkylphenol polyoxyethylene ether, polyether polyol or polyol fatty acid ester, and the polyalkyl organic matter inhibits the deposition of asphaltene by adsorbing on the surface of the medium to form a protective layer of hydrocarbon derivatives; and the auxiliary agent is a surfactant.

3. A method for deashing by solvent extraction of coal direct liquefaction residue according to claim 2, characterized in that: The surfactant is selected from one or more of sodium dodecyl sulfonate, dodecylbenzene sulfonic acid, benzoic acid and dodecylphenol.

4. The method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (1), the particle size of the liquefied residue after grinding is less than 2 mm; the heating method of the configuration tank is oil bath heating, steam heating or electric heating; the stirring rate of the extractant and scale inhibitor in the configuration tank is 80 to 200 rpm, and the stirring time is 10 to 45 min; after adjusting the pressure to 0.1 to 0.3 MPa, the stirring rate is adjusted to 100 to 250 rpm; and the constant temperature time is 30 to 90 min.

5. The method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (2), a decanter centrifuge is used for centrifugal separation, the separation linear speed of the decanter centrifuge is 60 to 120 m / s, and the temperature inside the centrifuge is 70 to 120°C.

6. The method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (3), the solid content of the extract obtained by centrifugal separation is less than 1-2%; the filter has a maximum pressure resistance of 2.0 MPa and a maximum temperature resistance of 260°C.

7. The method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (3), the specific steps of precision filtration are: Step 1: Feeding - filtration - positive blowing: preheat the filter to 80-120℃ and keep it constant. The extract in the centrifuge is continuously pumped into the filter through the inlet. When the pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding; at this time, start N2 positive blowing mode, positive blowing pressure ≤ 3kgf / cm 2 , wait for the outlet pressure difference to be less than 0.5kgf / cm 2 Stop N2 purging, and the extract in the centrifuge is continuously pumped into the filter again. The pressure difference between the inlet and outlet of the filter is greater than 2.5kgf / cm 2 Stop feeding and start the positive blowing mode again. When the pressure difference between feed-filter-filter outlet is greater than 2.5kgf / cm 2 - Positive blowing - outlet pressure difference is less than 0.5kgf / cm 2 Repeat the operation cycle in this mode until the pressure difference between the inlet and outlet of the filter after positive blowing is still greater than 2.5kgf / cm 2 This mode is terminated and the backflush mode of step 2 is entered; Step 2: Backflush: Turn on N2 backflush, backflush gas pressure ≤ 5kgf / cm 2 After a period of time, stop N2 backflushing, the filter residue on the surface of the filter element is blown to the bottom of the filter by nitrogen, the filter element restores the filtrate flux, and enters step 1. The filter residue at the bottom of the filter is discharged regularly.

8. The method for deashing coal direct liquefaction residue by solvent extraction according to claim 1, characterized in that: In step (5), the drying temperature of the dryer is 200-300° C., and the drying time is 0.5-3 h.

9. A refined asphalt, characterized in that: The asphalt is obtained by a coal direct liquefaction residue solvent extraction deashing method as claimed in any one of claims 1 to 8, wherein the ash content of the deashed refined asphalt is less than 200 ppm and the content of quinoline insoluble matter is less than 0.05%.

10. The use of a refined asphalt according to claim 9, characterized in that: The application is to use the refined asphalt as a raw material for high-performance asphalt-based carbon fiber, foam carbon lithium-ion battery negative electrode material or high-end carbon material of needle coke.

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