Method and system for desolidification and deashing of coal direct liquefaction residue and separation of components

Abstract

The present application relates to a method and system for desolidification and deashing of coal direct liquefaction residue and component separation, the method comprising: mixing coal direct liquefaction residue raw material with a first extraction solvent to perform extraction to obtain a first extraction phase and a first extraction residue phase; contacting the first extraction residue phase with a second extraction solvent to perform extraction to obtain a second extraction phase and a second extraction residue phase; contacting the first extraction phase and the second extraction phase with a third extraction solvent to perform extraction to obtain a third extraction phase; mixing the second extraction residue phase with a fourth extraction solvent to perform separation to obtain a solid product and a gas product; performing separation on the third extraction phase to obtain a light extraction component phase and a heavy extraction component phase; performing separation on the light extraction component phase to obtain a solvent and a light extraction component phase; the first extraction solvent, the second extraction solvent, the third extraction solvent and the fourth extraction solvent comprising one or more of C5-C8 hydrocarbons, low-carbon alcohols and low-carbon ethers. The method can realize component separation while removing solid powder through solvent extraction.

Description

Technical Field

[0001] This invention relates to the field of coal direct liquefaction residue treatment technology, specifically to a method and system for desolidification, deashing, and component separation of coal direct liquefaction residue. Background Technology

[0002] Coal direct liquefaction residue is a byproduct of coal hydroliquefaction. The liquefaction product contains oil produced during the hydrocracking process. After atmospheric or vacuum distillation, the oil is extracted from the top and side streams of the distillation column. The bottom product contains complex, high-boiling-point organic compounds, known in the industry as bitumen, with a content exceeding 50%. This bitumen can be used as a raw material for the preparation of carbon materials and has high application value. However, the residue also contains a large amount of unconverted coal powder, ash, and catalyst powder, with an average particle size generally less than 50 μm. Due to the high softening point and high viscosity of the residue, it is difficult to remove these solid powders using simple sedimentation separation methods. There is no unified definition of solids in coal liquefaction residue; different separation methods will yield different solid contents. Generally, the content of quinoline insolubles (QI) is used as a benchmark, and its content can even reach 50 wt%, with ash content exceeding 15 wt%. Currently, industrial methods for removing powdery solids include solvent sedimentation and solvent centrifugal separation sedimentation. Due to the small particle size of powdery solids, solvent sedimentation is extremely time-consuming, sometimes taking up to 72 hours. Solvent centrifugation, on the other hand, has limited capacity per unit, requiring multiple centrifuges for large-scale industrial coal direct liquefaction plants. The reproducibility of separation conditions across multiple units makes it difficult to maintain consistent product quality. Furthermore, while both methods offer some descaling and ash removal, they struggle to achieve complete component separation.

[0003] Supercritical solvent extraction not only boasts high yield and selective extraction capabilities but also rapid mass transfer. In the petroleum industry, solvent deasphalting widely employs subcritical extraction and supercritical solvent recovery. During extraction, the settling and separation time of the residue oil is only tens of minutes, while the residence time in supercritical solvent recovery is only a few minutes. Conventional solvent deasphalting typically uses C3-C5 light hydrocarbons as solvents. The asphalt components in the separated feedstock residue oil are essentially free of toluene-insoluble matter and have very low ash content. The resulting raffinate is generally discharged as liquid asphalt. In cases where the deasphalted asphalt has a high softening point (90-110℃), it can be granulated in water after high-temperature stripping to separate the solvent. There are also cases where supercritical extraction of high-softening-point asphalt is coupled with granulation. The separated high-softening-point asphalt (up to 180℃) is directly granulated. The gas-solid separation temperature in the granulation tower is relatively low, but the solvent involved is relatively light. Nitrogen is directly injected into the granulation tower to enhance solvent separation. This method is not suitable for removing solid powdery substances discharged under the high extraction temperatures required for coal liquefaction residue extraction.

[0004] Therefore, there is an urgent need to develop a method to better solve the problem of solidification and separation of coal liquefaction residue, and to achieve the separation of components. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for desolidification, deashing, and component separation of coal direct liquefaction residue. This method can achieve component separation while removing solid powder through solvent extraction.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for desolidification, deashing, and component separation of coal direct liquefaction residue, the method comprising: The raw material of direct coal liquefaction is mixed with the first extraction solvent in a mixer and then fed into an extraction tower for extraction to obtain the first extract phase and the first raffinate phase. The first raffinate phase is contacted with the second extraction solvent for extraction to obtain the second extract phase and the second raffinate phase. The first and second extract phases are contacted with a third extract solvent for extraction to obtain a third extract phase. The second raffinate phase is mixed with the fourth extraction solvent and then fed into the raffinate residue granulation tower for gas-solid phase change separation under nitrogen medium to obtain solid products and gaseous products. The third extraction phase is subjected to extraction component separation to obtain a light extraction component phase and a heavy extraction component phase; The light extractable phase is subjected to solvent separation in a solvent recovery tower after being heated or depressurized to obtain the solvent and the light extractable phase. The gaseous product is condensed and used as the fourth extraction solvent for the gas-solid phase change separation; the solvent is cooled and used as the first, second, and third extraction solvents for the extraction, respectively. The first extraction solvent, the second extraction solvent, the third extraction solvent, and the fourth extraction solvent each independently include one or more of C5-C8 hydrocarbons, C1-C4 low-carbon alcohols, and C1-C4 low-carbon ethers.

[0007] Optionally, the C5-C8 hydrocarbons include one or more of isopentane, n-pentane, n-hexane, cyclopentane, cyclohexane, benzene, toluene, ethylbenzene, and xylene; The C1-C4 low-carbon alcohols include one or more of methanol, ethanol, n-propanol, and isopropanol; The C1-C4 low-carbon ethers include one or more of dimethyl ether, methyl ethyl ether, and diethyl ether; Optionally, the mass ratio of the first extraction solvent to the coal direct liquefaction residue raw material is 0.2-2.0:1; The mass ratio of the second extraction solvent to the coal direct liquefaction residue raw material is 0.2-3.0:1; The mass ratio of the third extraction solvent to the coal direct liquefaction residue raw material is 0.1-1.0:1.

[0008] Optionally, the extraction temperature is 120-350℃, the pressure is 1.6-12.0MPa, and the time is 15-120min.

[0009] Optionally, the mass ratio of the fourth extraction solvent to the second raffinate phase is 0.1-0.5:1.

[0010] Optionally, the gas-solid phase change separation temperature is higher than the boiling point of the fourth extraction solvent; The extraction components are separated at a temperature of 125-400℃ and a pressure of 1.6-12.0 MPa. The solvent separation temperature is 200-360℃, the pressure is 1.6-12.0MPa, and the time is 3-30min.

[0011] Optionally, the method further includes: stripping the light extraction component phase and the heavy extraction component phase with high-temperature steam to obtain a gaseous solvent, and then condensing and recycling the gaseous solvent.

[0012] The second aspect of this invention provides a system for desolidification, deashing, and component separation of coal direct liquefaction residue. This system is used to implement the method for desolidification, deashing, and component separation of coal direct liquefaction residue provided in the first aspect of this invention. The system includes a raw material pump, a mixer, an extraction tower, a heat exchanger, an extraction component separation tower, a heater, and a solvent recovery tower connected in sequence. The solvent recovery tower is connected to a solvent recovery pump and an air cooler in sequence through the heat exchanger. The extraction tower is also connected in sequence to a granulation tower for raffinate residue, a gas-solid separator for raffinate powder, a first solvent condenser, a solvent N2 separator, a solvent tank, a solvent booster pump, and an air cooler. The extraction residue granulation tower is connected to a nitrogen source; the air cooler is returned to both the extraction tower and the extraction residue granulation tower.

[0013] Optionally, the extraction component separation tower is further connected to a heavy extraction component stripping tower; the solvent recovery tower is further connected to a light extraction component stripping tower; the light extraction component stripping tower and the heavy extraction component stripping tower are respectively connected to the solvent tank through a second solvent condenser.

[0014] Through the above technical solution, this invention uses C5-C8 hydrocarbons, low-carbon alcohols, low-carbon ethers, or mixtures thereof as solvents. While removing solid powders through solvent extraction in a liquid or subcritical state, the ash content in coal liquefaction residue containing solid powders can be reduced to below 0.1%. The extracted components can be further separated to meet the raw material requirements for producing higher value-added carbon materials. By heating or depressurizing the extract phase to reach a supercritical state for solvent separation, solvent recovery and recycling can be achieved. Furthermore, by mixing the raffinate phase with a fourth extraction solvent for gas-solid phase change separation, the solvent becomes gaseous and is condensed and recovered. This solves various problems encountered in conventional solvent sedimentation and centrifugal separation processes, such as the long time required for solvent precipitation and the need for multiple centrifugal separation units.

[0015] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system for desolidification, deashing, and component separation of coal direct liquefaction residue according to the present invention.

[0017] Explanation of reference numerals in the attached figures 01-Raw material pump; 02-Mixer; 03-Extraction tower; 04-Heat exchanger; 05-Extraction component separation tower; 06-Heater; 07-Solvent recovery tower; 08-Solvent recovery pump; 09-Residue granulation tower; 10-Residue powder gas-solid separator; 11-Powder cooler; 12-First solvent condenser; 13-Light extraction component stripping tower; 14-Second solvent condenser; 15-Heavy extraction component stripping tower; 16-Solvent N2 separator; 17-Solvent tank; 18-Solvent booster pump; 19-Air cooler. Detailed Implementation

[0018] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] The first aspect of this invention provides a method for desolidification, deashing, and component separation of coal direct liquefaction residue, the method comprising: The coal direct liquefaction residue raw material is mixed with the first extraction solvent in mixer 02 and then fed into extraction tower 03 for extraction to obtain the first extract phase and the first raffinate phase. The first raffinate phase is contacted with the second extraction solvent for extraction to obtain the second extract phase and the second raffinate phase. The first and second extract phases are contacted with a third extract solvent for extraction to obtain a third extract phase. The second raffinate phase is mixed with the fourth extraction solvent and then fed into the raffinate residue granulation tower 09. Gas-solid phase change separation is carried out under nitrogen medium to obtain solid products and gaseous products. The third extraction phase is subjected to extraction component separation to obtain a light extraction component phase and a heavy extraction component phase; The light extractable phase is subjected to solvent separation in solvent recovery tower 07 after being heated or depressurized to obtain solvent and light extractable phase; The gaseous product is condensed and used as the fourth extraction solvent for the gas-solid phase change separation; the solvent is cooled and used as the first, second, and third extraction solvents for the extraction, respectively. The first extraction solvent, the second extraction solvent, the third extraction solvent, and the fourth extraction solvent each independently include one or more of C5-C8 hydrocarbons, C1-C4 low-carbon alcohols, and C1-C4 low-carbon ethers.

[0020] In this invention, the coal direct liquefaction residue is a byproduct of the coal hydrogenation liquefaction process. The liquefied coal product contains oil produced during the hydrogenation process, including a large amount of unconverted coal powder and ash, etc. After atmospheric or vacuum distillation, the oil is extracted from the top and side stream of the column, but the powdery solids remain in the bottom products of atmospheric and vacuum distillation, resulting in atmospheric residue, vacuum residue, and a mixture of vacuum residue and vacuum side stream, with a density at 20°C higher than 1.300 g / cm³. 3 Its viscosity at 350℃ is less than 3000 mPa·s, of which the fraction with a boiling point <350℃ does not exceed 5 wt%, and its softening point is below 250℃.

[0021] According to the present invention, optionally, the solid powder in the coal direct liquefaction residue raw material is based on quinoline insoluble matter (including ash), the quinoline insoluble matter content is less than 50 wt%, the ash content is not more than 15 wt%, the average particle size is 30-100 μm, and the maximum particle size is ≤240 μm.

[0022] According to the present invention, optionally, the temperature of the coal direct liquefaction residue feedstock in the static mixer is 50°C higher than its softening point, preferably 100°C higher than the softening point, but the maximum temperature is lower than 350°C, the discharge temperature is 150~350°C, and the pressure is 1.6~12.0MPa, which can be connected with the upstream process to maintain suitable fluidity without overheating and coking.

[0023] According to the present invention, optionally, the C5-C8 hydrocarbons include one or more of isopentane, n-pentane, n-hexane, cyclopentane, cyclohexane, benzene, toluene, ethylbenzene, and xylene; the C1-C4 low-carbon alcohols include one or more of methanol, ethanol, n-propanol, and isopropanol; and the C1-C4 low-carbon ethers include one or more of dimethyl ether, methyl ethyl ether, and diethyl ether.

[0024] The critical temperature of the extraction solvent in this invention is between 150 and 360°C; if the extraction solvent is a mixture, the critical temperature of the solvent fraction is calculated based on the pseudo-critical temperature. The critical pressure is In the formula x i It is the mole fraction of component i. Tc i It is its critical temperature, in K. n It represents the number of components in the solvent, and Pc is the critical pressure, measured in MPa.

[0025] This invention selects solvents with boiling points and carbon numbers significantly lower than those used in solvent sedimentation and centrifugal separation of coal tar pitch and coal liquefaction residues. The hydrocarbon solvents have carbon numbers between C5 and C8, while the low-carbon alcohols and low-carbon ethers have even lower carbon numbers between C1 and C3. This achieves good component separation selectivity while simultaneously removing solids and ash, and the lower boiling point of the solvent makes solvent recovery relatively easy. To ensure the solvent's solubility, address the difficulties in separation and mass transfer, and match the flowability of upstream materials, extraction separation is performed in the solvent's high-temperature liquid state and near-critical state.

[0026] According to the present invention, optionally, the fourth extraction solvent includes one or more of C5-C8 hydrocarbons, C1-C4 low-carbon alcohols, and C1-C4 low-carbon ethers. The fourth extraction solvent of the present invention can significantly reduce the viscosity of the raffinate phase, transforming it from a paste into a pumpable, atomizable slurry or solution; it can alter the surface properties of solid particles, making them easier to disperse by hot gas flow, while simultaneously preventing powder particles from agglomerating, thus obtaining dispersed powder.

[0027] According to the present invention, optionally, the mass ratio of the first extraction solvent to the coal direct liquefaction residue raw material is 0.2-2.0:1; The mass ratio of the second extraction solvent to the coal direct liquefaction residue raw material is 0.2-3.0:1; The mass ratio of the third extraction solvent to the coal direct liquefaction residue raw material is 0.1-1.0:1.

[0028] According to the present invention, optionally, the extraction temperature refers to the average temperature at the bottom and top of the column, wherein the extraction temperature is 120-350℃; the pressure refers to the pressure at the top of the column, wherein the pressure is 1.6-12.0 MPa; and the time refers to the average residence time, wherein the time is 15-120 min. The average residence time is calculated as follows: τ=60V / Q Where Q is the total volumetric flow rate entering the tower, m 3 / h; V - Total tower volume, m 3 τ - Average residence time, min. The above method for calculating the average residence time is also applicable to other equipment using this method.

[0029] According to the present invention, optionally, the extraction preferred temperature and pressure are determined according to the comparison temperature and comparison pressure, preferably the comparison temperature Tr=T / Tc ranges from 0.5 to 1.0, and preferably the comparison pressure Pr=P / Pc ranges from 0.5 to 2.0.

[0030] According to the present invention, optionally, the mass ratio of the fourth extraction solvent to the second raffinate phase is 0.05-0.5:1.

[0031] According to the present invention, optionally, the gas-solid phase change separation temperature is higher than the boiling point of the fourth extraction solvent, preferably 20°C higher. Pressure refers to the gas phase pressure measured at the top of the raffinate granulation tower. The N2 temperature is 120~200°C, and its circulation rate is 1-3 wt% of the amount of raffinate entering the raffinate granulation tower.

[0032] According to the present invention, optionally, the temperature for separating the extraction components is 125-400℃, and the pressure is 1.6-12.0MPa; the temperature of the extraction component separation tower is 5-50℃ higher than that of the extraction tower, and the pressure is the value after overcoming the natural pressure drop due to flow resistance, preferably 0.1-0.2MPa lower than the pressure of the extraction tower, and the average residence time for separation is 5-60min.

[0033] According to the present invention, optionally, the solvent separation temperature is 200-360℃, the pressure is 1.6-12.0 MPa, and the time is 3-30 min. Preferably, the pressure is 0.1-0.2 MPa lower than the extraction tower pressure, and preferably, the temperature is determined by the solvent density, with a solvent density of 0.16 g / cm³. 3 The corresponding temperature and the temperature within 10°C above this temperature. If this temperature exceeds 360°C, reduce the pressure of the solvent recovery tower to meet the solvent density requirements.

[0034] According to the present invention, optionally, the method further includes: stripping the light extraction component phase and the heavy extraction component phase with high-temperature steam to obtain a gaseous solvent, and recycling the gaseous solvent after condensation.

[0035] The second aspect of this invention provides a system for desolidification, deashing, and component separation of coal direct liquefaction residue. This system is used to implement the method for desolidification, deashing, and component separation of coal direct liquefaction residue provided in the first aspect of this invention. See also... Figure 1 The system includes a raw material pump 01, a mixer 02, an extraction tower 03, a heat exchanger 04, an extraction component separation tower 05, a heater 06, and a solvent recovery tower 07 connected in sequence; the solvent recovery tower 07 is connected in sequence to a solvent recovery pump 08 and an air cooler 19 through the heat exchanger 04. The extraction tower 03 is also connected in sequence to the raffinate residue granulation tower 09, the raffinate powder gas-solid separator 10, the first solvent condenser 12, the solvent N2 separator 16, the solvent tank 17, the solvent booster pump 18, and the air cooler 19. The granulation tower 09 for the raffinate residue is connected to a nitrogen source; the air cooler 19 is returned to the extraction tower 03 and the granulation tower 09 for the raffinate residue.

[0036] According to the present invention, optionally, the extraction component separation tower 05 is further connected to a heavy extraction component stripping tower 15; the solvent recovery tower 07 is further connected to a light extraction component stripping tower 13; the light extraction component stripping tower 13 is connected to the solvent tank 17 through a second solvent condenser 14.

[0037] The specific process flow of the coal direct liquefaction residue desolidation, deashing, and component separation system of this invention includes: The raw material containing coal liquefaction residue containing powder is pressurized to a certain pressure by the raw material pump 01 and mixed with the first extraction solvent (as shown in the flow chart S1) in the mixer 02. The resulting mixture enters the middle of the extraction tower 03 for sedimentation and separation extraction. In the extraction tower 03, it is separated into a first extract phase (containing extract components and solvent, the same below) and a first raffinate phase (containing raffinate components, solid powder and solvent, the same below). The second extraction solvent (as shown in the flow chart S3) enters the bottom of the extraction tower 03. The second extraction solvent comes into countercurrent contact with the first raffinate phase for extraction, further extracting the soluble components. The final second raffinate phase is discharged from the bottom of the tower. The second extract phase flows upward and comes into contact with the first extract phase and the injected third extraction solvent to further remove solid powder. The third extraction solvent (as shown in the flow chart S2) enters above the feed inlet of the extraction tower 03, and the final third extract phase flows out from the top of the tower.

[0038] A fourth extraction solvent (as shown in the flow chart S4) is added to the second raffinate phase and mixed before entering the raffinate residue granulation tower 09 for gas-solid phase change separation. N2 is injected into the granulation tower to further strip the solvent from the powder, dispersing the raffinate residue into powder. The solvent becomes gaseous and enters the raffinate powder gas-solid separator 10 for further separation. The gaseous solvent and nitrogen at the top of the raffinate powder gas-solid separator 10 are condensed by the first solvent condenser 12 and then enter the solvent N2 separator 16. The separated nitrogen is returned to the raffinate residue granulation tower 09, while the solvent is recovered in the solvent tank 17 and pressurized by the solvent booster pump 18 before entering the high-pressure air cooler 19. After cooling, the solvent enters the raffinate residue granulation tower 09 for recycling. The powder material discharged from the bottom of the raffinate residue granulation tower 09 and the bottom of the raffinate powder gas-solid separator 10 enters the powder cooler 11 and is cooled to below 50°C.

[0039] The third extraction phase (containing the extraction component and solvent) enters the extraction component separation tower 05 after the temperature and pressure remain unchanged (the natural pressure drop caused by the flow is negligible) by raising or lowering the temperature to reduce the solvent's solubility. It is further separated into light and heavy phases. The light extraction component phase flows out from the top of the tower, and the heavy extraction component phase flows out from the bottom of the tower.

[0040] The light extractable component phase enters the solvent recovery tower 07 via heater 06 for solvent separation. By raising the temperature or lowering the pressure in heater 06, the solvent is separated into a supercritical or gaseous state, causing it to lose its ability to dissolve the light component. The solvent from the top of solvent recovery tower 07, after being de-cooled by heat exchanger cyclone separator 04, is then pressurized by solvent recovery pump 08 and enters high-pressure air cooler 19, where it is cooled to the temperature and pressure required to enter mixer 02 and extraction tower 03 for recycling.

[0041] The light extract component (light bitumen) from the bottom of solvent recovery tower 07 and the heavy extract component (heavy bitumen) separated from the bottom of extract component separation tower 05 are depressurized and enter light extract component stripping tower 13 and heavy extract component stripping tower 15, respectively. The residual solvent is recovered by high-temperature steam stripping. The solvent gas is cooled by solvent condenser 14 and enters solvent tank 17. After being pressurized by solvent booster pump 18, it enters high-pressure air cooler 19 and is then cooled and recycled.

[0042] Through the above technical solution, the present invention has the following technical effects: (1) To address the problem of removing solids from raw materials with high solid content powders, C5-C8 hydrocarbons, low-carbon alcohols, low-carbon ethers, or mixtures thereof are used as solvents. Through the strong mass transfer capacity of the solvent in liquid, subcritical, or supercritical states, the separation time can be significantly reduced. While removing solid powders, the ash content in coal liquefaction residue containing solid powders can be removed to below 0.1 wt%. The extracted components can also be further separated by adjusting the solvent density and temperature to meet the raw material requirements for producing higher value-added carbon materials. For example, the quinoline insoluble content (QI) of the light extraction component (light pitch) (analyzed according to GB / T2293-2019 method) can be reduced to below 0.5 wt%, which can be used to prepare impregnated pitch, mesophase pitch, and needle coke. The QI content of the heavy extraction component (heavy pitch) can be reduced to below 1.0 wt%, which can be used to prepare coated pitch, mesophase pitch, and needle coke.

[0043] (2) The extract phase at the top of the extraction tower is heated to a supercritical state and enters the solvent recovery tower. The light extract components are effectively separated from the solvent at a lower solvent density. More than 85% of the total circulating solvent can be recovered from here and directly circulated back to the static mixer and extraction tower under high pressure.

[0044] (3) In the extraction process, the coupled raffinate phase and the fourth extraction solvent are mixed, sprayed, dispersed, granulated and recovered to solve various problems encountered in conventional solvent sedimentation and solvent centrifugation processes, such as the long time required for solvent precipitation and the need for multiple sets of centrifugation equipment.

[0045] The present invention will be further illustrated by the following examples, but the present invention is not limited thereto.

[0046] Example 1 A method for desolidification, deashing, and component separation of coal direct liquefaction residue includes the following steps: The coal direct liquefaction residue feedstock is mixed with the first extraction solvent in mixer 02 and then fed into extraction tower 03 for extraction to obtain the first extract phase and the first raffinate phase. The coal direct liquefaction residue feedstock has a TI (toluene-insoluble matter) content of 51.34 wt% (tested according to GB / T 2292), a QI (quinoline-insoluble matter) content of 37.94 wt% (tested according to GB / T 2293), an ash content of 11.62 wt%, an average particle size of 45 μm, and a maximum particle size of 200 μm. The mixer outlet temperature is between 270-280℃, and the pressure is 6.0 MPa. The mass ratio of the first extraction solvent to the coal direct liquefaction residue feedstock is 2.0:1. The first raffinate phase is contacted with the second extraction solvent for extraction to obtain the second extract phase and the second raffinate phase; the mass ratio of the second extraction solvent to the coal direct liquefaction residue raw material is 2.0:1. The first and second extract phases are contacted with a third extract solvent for extraction to obtain the third extract phase; the mass ratio of the third extract solvent to the coal direct liquefaction residue raw material is 1.0:1; the first, second, and third extract solvents are each independently toluene, with a critical temperature of 318.6℃ and a critical pressure of 4.11MPa. The second raffinate phase is mixed with the fourth extraction solvent and then fed into the raffinate powder granulation tower 08. Gas-solid phase change separation is performed under nitrogen medium to obtain solid and gaseous products. The gaseous product enters the raffinate powder gas-solid separator 09 for further separation. The gaseous solvent and nitrogen at the top of the raffinate powder gas-solid separator 09 are condensed by the first solvent condenser 11 and then enter the solvent N2 separator 14. The separated nitrogen is returned to the raffinate powder granulation tower 08, while the solvent is recovered in the solvent tank 15, pressurized by the solvent booster pump 16, and then cooled before entering the raffinate powder granulation tower 08 for recycling. The mass ratio of the fourth extraction solvent to the second raffinate phase is 0.5:1. The third extraction phase (containing the extraction component and solvent) is heated to 300°C under a pressure of 4.8 MPa (natural pressure drop from the extraction tower to the separation tower) and then enters the extraction component separation tower 05, where it is further separated into light and heavy phases. The light extraction component phase flows out from the top of the tower, and the heavy extraction component phase flows out from the bottom of the tower. The light extractable phase is heated by heater 06 and then fed into solvent recovery tower 07 for solvent separation to obtain solvent and light extractable phase (light asphalt). The solvent is cooled and used as the first, second, and third extraction solvents for extraction. The light extractable phase is separated from the solvent at a pressure of 4.6 MPa and a temperature of 350 °C, reaching a supercritical state or gaseous state. Under these separation conditions, the solvent density decreases to 0.147 g / cm³. 3 ; The light extract component (light bitumen) from the bottom of solvent recovery tower 07 and the heavy extract component (heavy bitumen) separated from the bottom of extract component separation tower 05 are depressurized and fed into light extract component stripping tower 13 and heavy extract component stripping tower 15, respectively. The residual solvent is recovered by high-temperature steam stripping. The solvent gas is cooled by solvent condenser 14 and enters solvent tank 17. After being pressurized by solvent booster pump 18, it enters high-pressure air cooler 19 and is then cooled and recycled.

[0047] The separation effect of this embodiment is shown in Table 1: Table 1

[0048] Example 2 This embodiment of the method for desolidification, deashing, and component separation of coal direct liquefaction residue is the same as that in Embodiment 1, except that: The coal direct liquefaction residue feedstock has a TI content of 58.70%, a QI content of 38.62 wt%, an ash content of 14.37 wt%, an average particle size of 46 μm, and a maximum particle size of 240 μm; the mixer outlet temperature is between 260-270℃, and the pressure is 5.5 MPa; the mass ratio of the first extraction solvent to the coal direct liquefaction residue feedstock is 1.0:1; the mass ratio of the second extraction solvent to the coal direct liquefaction residue feedstock is 2.0:1; and the mass ratio of the fourth extraction solvent to the second raffinate phase is 0.4:1. The third extract phase, under a pressure of 4.8 MPa (natural pressure drop from the extraction tower to the separation tower), is heated to 280°C and then enters the extraction component separation tower 05 for further separation into light and heavy phases.

[0049] The separation effect of this embodiment is shown in Table 2: Table 2

[0050] Example 3 This embodiment of the method for desolidification, deashing, and component separation of coal direct liquefaction residue is the same as that in Embodiment 1, except that: The coal direct liquefaction residue feedstock has a QI content of 34.45 wt%, an ash content of 9.51 wt%, an average particle size of 49 μm, and a maximum particle size of 220 μm; the mixer outlet temperature is between 265-275℃, and the pressure is 5.0 MPa; the mass ratio of the first extraction solvent to the coal direct liquefaction residue feedstock is 1.0:1; the mass ratio of the second extraction solvent to the coal direct liquefaction residue feedstock is 2.0:1; and the mass ratio of the fourth extraction solvent to the second raffinate phase is 0.4:1. The third extract phase, under a pressure of 4.8 MPa (natural pressure drop from the extraction tower to the separation tower), is heated to 290°C and then enters the extraction component separation tower 05 for further separation into light and heavy phases.

[0051] The separation effect of this embodiment is shown in Table 3: Table 3

[0052] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0053] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0054] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for desolidification, deashing, and component separation of coal direct liquefaction residue, characterized in that, The method includes: The coal direct liquefaction residue raw material is mixed with the first extraction solvent in a mixer (02) and then fed into an extraction tower (03) for extraction to obtain the first extract phase and the first raffinate phase; The first raffinate phase is contacted with the second extraction solvent for extraction to obtain the second extract phase and the second raffinate phase. The first and second extract phases are contacted with a third extract solvent for extraction to obtain a third extract phase. The second raffinate phase is mixed with the fourth extraction solvent and then fed into the raffinate residue granulation tower (09) for gas-solid phase change separation under nitrogen medium to obtain solid products and gaseous products. The third extraction phase is subjected to extraction component separation to obtain a light extraction component phase and a heavy extraction component phase; The light extractable phase is subjected to solvent separation in a solvent recovery tower (07) after being heated or depressurized to obtain solvent and light extractable phase; The gaseous product is condensed and used as the fourth extraction solvent for the gas-solid phase change separation; the solvent is cooled and used as the first, second, and third extraction solvents for the extraction, respectively. The first extraction solvent, the second extraction solvent, the third extraction solvent, and the fourth extraction solvent each independently include one or more of C5-C8 hydrocarbons, C1-C4 low-carbon alcohols, and C1-C4 low-carbon ethers.

2. The method according to claim 1, wherein, The C5-C8 hydrocarbons include one or more of isopentane, n-pentane, n-hexane, cyclopentane, cyclohexane, benzene, toluene, ethylbenzene, and xylene; The C1-C4 low-carbon alcohols include one or more of methanol, ethanol, n-propanol, and isopropanol; The C1-C4 low-carbon ethers include one or more of dimethyl ether, methyl ethyl ether, and diethyl ether.

3. The method according to claim 1, wherein, The mass ratio of the first extraction solvent to the coal direct liquefaction residue raw material is 0.2-2.0:1; The mass ratio of the second extraction solvent to the coal direct liquefaction residue raw material is 0.2-3.0:1; The mass ratio of the third extraction solvent to the coal direct liquefaction residue raw material is 0.1-1.0:

1.

4. The method according to claim 1, wherein, The extraction temperature is 120-350℃, the pressure is 1.6-12.0MPa, and the time is 15-120min.

5. The method according to claim 1, wherein, The mass ratio of the fourth extraction solvent to the second raffinate phase is 0.1-0.5:

1.

6. The method according to claim 1, wherein, The gas-solid phase change separation temperature is higher than the boiling point of the fourth extraction solvent; The extraction components are separated at a temperature of 125-400℃ and a pressure of 1.6-12.0 MPa.

7. The method according to claim 1, wherein, The solvent separation temperature is 200-360℃, the pressure is 1.6-12.0MPa, and the time is 3-30min.

8. The method according to claim 1, wherein, The method further includes: stripping the light extraction component phase and the heavy extraction component phase with high-temperature steam to obtain a gaseous solvent, and then condensing and recycling the gaseous solvent.

9. A system for desolidification, deashing, and component separation of coal direct liquefaction residue, characterized in that, The system is used to implement the method for desolidation, deashing and component separation of coal direct liquefaction residue as described in any one of claims 1-8. The system includes a raw material pump (01), a mixer (02), an extraction tower (03), a heat exchanger (04), an extraction component separation tower (05), a heater (06), and a solvent recovery tower (07) connected in sequence. The solvent recovery tower (07) is connected in sequence to a solvent recovery pump (08) and an air cooler (19) through the heat exchanger (04). The extraction tower (03) is also connected in sequence to the raffinate granulation tower (09), the raffinate powder gas-solid separator (10), the first solvent condenser (12), the solvent N2 separator (16), the solvent tank (17), the solvent booster pump (18) and the air cooler (19). The granulation tower (09) for the raffinate residue is connected to a nitrogen source; the air cooler (19) is returned to the extraction tower (03) and the granulation tower (09).

10. The system according to claim 9, wherein, The extraction component separation tower (05) is also connected to a heavy extraction component stripping tower (15); the solvent recovery tower (07) is also connected to a light extraction component stripping tower (13). The light extraction component stripping tower (13) and the heavy extraction component stripping tower (15) are respectively connected to the solvent tank (17) via a second solvent condenser (14).

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