Method for pre-treating slurry oil

Abstract

A method for pre-treating slurry oil. The method comprises the following steps: 1) using an organic polar solvent to perform an extraction treatment on slurry oil to obtain a raffinate phase comprising a solid-phase impurity and an extract phase comprising a target product; 2) sequentially performing flash evaporation and separation on the extract phase, and then filtering same to obtain a first recovery solvent and a residual component comprising the target product; 3) performing reduced-pressure distillation on the residual component to obtain a second recovery solvent and a target fraction; and 4) performing a first hydrogenation treatment and a second hydrogenation treatment on the target fraction to obtain refined slurry oil, wherein the first hydrogenation treatment is performed at a temperature of 300-330°C and a pressure of 2-4 MPa; and the second hydrotreatment is performed at a temperature of 320-380°C and a pressure of 3-8 MPa. The method can improve the utilization rate of the slurry oil and achieve deep removal of solids and impurities.

Description

A method for pretreatment of oil slurry

[0001] This application claims priority to Chinese Patent Application No. 202411223119.5, filed on September 2, 2024, entitled "A Method for Pretreatment of Oil Slurry", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to a method for pretreatment of oil slurry, which belongs to the field of petrochemicals. Background Technology

[0003] Short-chain 3- and 4-cyclic aromatic hydrocarbons are ideal components for preparing precursors of carbon materials such as mesophase pitch and needle coke. These short-chain 3- and 4-cyclic aromatic hydrocarbons can be obtained by enrichment and processing from oil slurry. However, oil slurry resources are quite complex in composition, containing not only ideal components but also catalyst dust, olefins, saturated hydrocarbons, gums, asphaltenes, 1- and 2-cyclic light aromatic hydrocarbons, polycyclic aromatic hydrocarbons with more than 4 rings, long-chain 3- and 4-cyclic aromatic hydrocarbons, and heteroatom compounds containing sulfur, nitrogen, oxygen, or metals, among other non-ideal components.

[0004] Therefore, enrichment treatment must not only achieve efficient separation of solid particles such as catalyst powder in the slurry, but also remove or transform all or part of the non-ideal components such as gums, asphaltenes, olefins, polycyclic aromatic hydrocarbons and long side-chain aromatic hydrocarbons. In addition, it is also necessary to partially remove heterocyclic aromatic hydrocarbons containing sulfur and nitrogen atoms in the slurry to ensure efficient enrichment of 3- and 4-cyclic aromatic hydrocarbons with shorter side chains.

[0005] Patent document CN201910896551.3 discloses a method for preparing needle coke feedstock oil using oil slurry. The specific steps of this invention are as follows: low molecular weight n-alkanes are added to the oil slurry at a certain temperature to remove asphalt, and the upper layer is collected after settling; solvent extraction is performed, and the lower layer is collected after settling; solidification is performed; the solidified aromatic oil is fractionated; and the fractionated aromatic oil is hydrotreated for desulfurization and denitrogenation to obtain needle coke feedstock oil. The core technical route of this invention involves removing some gum, asphalt, and saturated components from the oil slurry, then solidifying the low molecular weight n-alkanes and extractant together, followed by vacuum distillation to recover the low molecular weight n-alkanes and extractant, and finally hydrotreating the remaining aromatic components for desulfurization and denitrogenation to obtain needle coke feedstock oil. However, this method has a low oil slurry utilization rate. Patent document CN201910868239.3 discloses a method for selective hydrodesulfurization of oil slurry while retaining aromatics. This invention first utilizes ultrasonic-assisted centrifugation to remove catalyst particles from the middle layer of the oil slurry; the mechanical action of ultrasound effectively improves the removal efficiency. Next, residual catalyst particles, asphaltenes, and gums in the oil slurry are removed, while retaining the extractable oil enriched with aromatics. Finally, the extractable oil is selectively hydrodesulfurized. However, this method selectively hydrogenates the deconsolidated oil slurry, resulting in a low oil slurry utilization rate.

[0006] Therefore, it is urgent for technicians to explore enrichment treatment methods that can improve the utilization rate of oil slurry and achieve deep deconsolidation and impurity removal. Summary of the Invention

[0007] This application provides a method for pretreatment of oil slurry, which can improve the utilization rate of oil slurry and achieve deep deconsolidation and impurity removal of oil slurry.

[0008] This application provides a method for pretreatment of oil slurry, including the following steps:

[0009] 1) The oil slurry is extracted using an organic polar solvent to obtain a raffinate phase containing solid impurities and an extract phase containing the target product.

[0010] 2) The extracted phase is subjected to flash evaporation and filtration sequentially to obtain the first recovered solvent and residual components including the target product;

[0011] 3) The residual components are subjected to vacuum distillation to obtain a second recovered solvent and the target fraction;

[0012] 4) The target fraction is subjected to a first hydrogenation treatment and a second hydrogenation treatment to obtain a refined oil slurry;

[0013] The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa.

[0014] The second hydrogenation treatment is carried out at a temperature of 320-380℃ and a pressure of 3-8MPa.

[0015] As described above, the yield of the fraction in the oil slurry with a distillation temperature below 450°C is ≥80%, and the target product fraction is the total fraction of the oil slurry.

[0016] In step 4), the target fraction is subjected to the first hydrogenation treatment and the second hydrogenation treatment in sequence;

[0017] The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa;

[0018] The second hydrogenation treatment is carried out at a temperature of 320-350℃ and a pressure of 3-5MPa.

[0019] As described above, the yield of the fraction from the oil slurry with a distillation temperature below 450°C is <80%, and the target fraction includes light and heavy fractions; the cut-off temperature between the light and heavy fractions is 400-480°C.

[0020] In step 4), the light fraction undergoes a first hydrogenation treatment, and the heavy fraction undergoes a second hydrogenation treatment;

[0021] The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa;

[0022] The second hydrogenation treatment is carried out at a temperature of 340-380℃ and a pressure of 4-8MPa.

[0023] In the method described above, the content of solid particles in the extraction phase is not higher than 150 ppm.

[0024] As described above, the content of solid particulate matter in the residual component is not higher than 50 ppm;

[0025] The residual components include residual organic polar solvents, wherein the mass ratio of the residual organic polar solvents to the organic polar solvents is N, and N ≤ 15%.

[0026] In the method described above, the organic polar solvent includes at least one of sulfur atoms, nitrogen atoms, and oxygen atoms, wherein the number of each of the sulfur atoms, nitrogen atoms, and oxygen atoms is independently 1-2; and the molecular weight of the organic polar solvent is less than 100.

[0027] In the method described above, the organic polar solvent includes at least one of NMP, DMF, furfural, phenol, and DMSO.

[0028] In the method described above, the mass ratio of the organic polar solvent to the oil slurry is (0.5-3):1, and the extraction temperature is 20-130℃.

[0029] As described above, the first hydrogenation treatment and the second hydrogenation treatment also independently include a catalyst, wherein the active component of the catalyst is selected from at least one of Group VIB and Group VIII; the active component accounts for ≥1.0% of the mass of the catalyst.

[0030] In the method described above, the active component of the first hydrogenation-treated catalyst includes at least one of W, Co, Mo, and Ni, and the active component of the second hydrogenation-treated catalyst includes at least one of Co, Mo, Ni, Pt, Pd, and Fe.

[0031] The oil slurry pretreatment method provided in this application employs extraction, flash evaporation, filtration, vacuum distillation, and hydrogenation. By defining the parameters of each treatment stage and dividing the hydrogenation treatment into a first hydrogenation treatment and a second hydrogenation treatment, the method effectively achieves gradient and depth removal of solid particles from the oil slurry, improves the desulfurization and denitrification rates, and simultaneously increases the amount of 3- and 4-cyclic aromatic hydrocarbons with shorter side chains, thereby improving the utilization rate of the oil slurry. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the oil slurry pretreatment process in a specific embodiment of this application. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] This application provides a method for pretreatment of oil slurry, including the following steps:

[0035] 1) Extract the oil slurry using an organic polar solvent to obtain a raffinate phase containing solid impurities and an extract phase containing the target product; 2) Separate the extract phase by flash evaporation and filtration to obtain a first recovered solvent and a residual component containing the target product; 3) Distill the residual component under reduced pressure to obtain a second recovered solvent and a target product fraction; 4) Perform a first hydrogenation treatment and a second hydrogenation treatment on the target product fraction to obtain a refined oil slurry; wherein the temperature of the first hydrogenation treatment is 300-330℃ and the pressure is 2-4MPa; the temperature of the second hydrogenation treatment is 320-380℃ and the pressure is 3-8MPa.

[0036] The oil slurry pretreatment method provided in this application can efficiently achieve deep desolidification and impurity removal of oil slurry, while enriching 3- and 4-cyclic aromatic hydrocarbons and improving the utilization rate of oil slurry. Figure 1 is a schematic diagram of the oil slurry pretreatment process in a specific embodiment of this application.

[0037] In this application, "oil slurry" refers to a mixture of components including short-chain 3- and 4-cyclic aromatics, catalyst dust, olefins, saturated hydrocarbons, gums, asphaltenes, 1- and 2-cyclic light aromatics, polycyclic aromatics with more than 4 rings, long-chain 3- and 4-cyclic aromatics, and heteroatom compounds containing sulfur, nitrogen, oxygen, and metals.

[0038] Among them, shorter side chains refer to side chains with 1-4 carbon atoms.

[0039] This application does not limit the type of slurry, and can select at least one of the slurries commonly used in the art, such as vacuum residue oil, external slurry, and circulating slurry, depending on the actual situation.

[0040] The solid content can be determined by using filter paper with a pore size of less than 1 μm, the group composition content can be determined by SH / T0659, the S content can be determined by GB / T17040, the N content can be determined by SH / T0657-2007, and the asphaltene content in the four components can be determined by SH / T0509-2010. The material properties in oil slurry and refined oil slurry can be determined.

[0041] In detail, in step 1), the oil slurry is extracted using an organic polar solvent to obtain a raffinate phase containing solid impurities and an extract phase containing the target product.

[0042] This application does not limit the specific method or equipment of the extraction process. In one specific embodiment, the extraction process is a tower extraction method. The organic polar solvent and the oil slurry can be mixed outside the tower and then enter from the middle of the tower, or they can enter from the top and bottom of the tower respectively, and then be in counter-current contact inside the tower. When the organic polar solvent and the oil slurry enter the tower separately, the one with higher density enters from the top of the tower, and the one with lower density enters from the bottom of the tower.

[0043] During the extraction process, the organic polar solvent destroys the inclusions formed by the asphaltenes and catalyst powder due to polar adsorption, releasing solid impurities (catalyst powder). The raffinate phase, which has low solubility with the organic polar solvent, is distributed in the upper layer due to its low density. Most of the catalyst powder in the oil slurry is stuck in the raffinate phase, while a small number of larger particles settle to the lower extraction phase, resulting in a raffinate phase containing solid impurities and an extraction phase containing the target product.

[0044] The raffinate phase, including solid impurities, can be separated into layers after settling, and some organic polar solvents can be separated to obtain raffinate oil rich in catalyst powder. The raffinate oil rich in catalyst powder can be recycled into the catalytic cracking unit to achieve efficient utilization of the catalyst.

[0045] In step 2), the extract phase is sequentially subjected to flash evaporation and filtration to obtain the first recovered solvent and residual components including the target product.

[0046] In detail, the extract phase containing the target product enters the flash separation unit for flash separation treatment to obtain the first recovered solvent and the flash residual oil slurry. The flash residual oil slurry enters the filtration treatment unit for filtration treatment to obtain the residual components containing the target product.

[0047] This application does not limit the specific type of filtration process, as long as it can remove solid phase impurities with larger particle sizes from the extraction phase.

[0048] In one specific embodiment, the filtration method is selected from at least one of dead-end filtration or cross-flow membrane filtration.

[0049] In step 3), the residual components are subjected to vacuum distillation to obtain the second recovered solvent and the target fraction.

[0050] During the vacuum distillation process, the temperature of vacuum distillation is controlled according to the boiling point of the organic polar solvent, so that the organic polar solvent remaining in the residual components is separated from the target fraction, and a second recovered solvent and the target fraction are obtained.

[0051] It is understandable that the first and second recycled solvents can be recycled as extractants for extraction processes.

[0052] Step 4) The target fraction is subjected to a first hydrogenation treatment and a second hydrogenation treatment to obtain a refined oil slurry; wherein the temperature of the first hydrogenation treatment is 300-330℃ and the pressure is 2-4MPa; the temperature of the second hydrogenation treatment is 320-380℃ and the pressure is 3-8MPa.

[0053] In one specific embodiment, performing a first hydrogenation treatment and a second hydrogenation treatment on the target fraction refers to performing a first hydrogenation treatment and a second hydrogenation treatment on the target fraction sequentially.

[0054] In another specific embodiment, the first hydrogenation treatment and the second hydrogenation treatment of the target fraction refer to performing the first hydrogenation treatment and the second hydrogenation treatment on different components in the target fraction respectively.

[0055] The refined oil slurry in this application can be used as a raw material for preparing mesophase pitch or needle coke.

[0056] This application does not limit the apparatus for the first hydrogenation treatment and the second hydrogenation treatment. A suitable apparatus can be selected according to the actual situation. In one specific embodiment, the first hydrogenation treatment and the second hydrogenation treatment are carried out in a hydrogenation reactor. The first hydrogenation treatment and the second hydrogenation treatment can be carried out in the same hydrogenation reactor or in two hydrogenation reactors.

[0057] The oil slurry pretreatment method provided in this application can achieve deep desolidification, desulfurization, and denitrification of the oil slurry, while also enriching 3- and 4-cyclic aromatic hydrocarbons with shorter side chains, thereby improving the utilization rate of the oil slurry. The inventors believe this is because, on the one hand, during the extraction stage, the use of organic polar solvents can release solid particles encapsulated by polar substances such as gums and asphaltenes. Combined with filtration, this achieves gradient and deep removal of solid particles. On the other hand, the target fraction undergoes first and second hydrogenation treatments. By controlling specific treatment temperatures and pressures, higher desulfurization and denitrification rates are achieved, while some other types of aromatic hydrocarbons are converted into 3- and 4-cyclic aromatic hydrocarbons with shorter side chains, thus increasing the quantity of these hydrocarbons and improving the utilization rate of the oil slurry.

[0058] Furthermore, in a specific embodiment of this application, the yield of the fraction in the oil slurry before the distillation temperature of 450°C is ≥80%, and the target product fraction is the total fraction of the oil slurry; in step 4), the target product fraction is subjected to a first hydrogenation treatment and a second hydrogenation treatment in sequence; the temperature of the first hydrogenation treatment is 300-330°C and the pressure is 2-4 MPa; the temperature of the second hydrogenation treatment is 320-350°C and the pressure is 3-5 MPa.

[0059] In detail, the oil slurry was subjected to high-temperature simulated distillation analysis according to ASTM D7169. When the cumulative yield before 450°C was ≥80%, the target product fraction was the total fraction of the oil slurry during the vacuum distillation process in step 3).

[0060] Subsequently, in step 4), the target fraction is subjected to a first hydrogenation treatment to obtain an intermediate product, and the intermediate product is subjected to a second hydrogenation treatment to obtain a refined oil slurry.

[0061] The temperature of the first hydrogenation treatment is 300-330℃, for example, including but not limited to 300℃, 305℃, 310℃, 315℃, 320℃, 325℃, 330℃, or any combination thereof. The pressure of the first hydrogenation treatment is 2-4 MPa, for example, including but not limited to 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, or any combination thereof. The temperature of the second hydrogenation treatment is 320-350℃, for example, including but not limited to 320℃, 325℃, 330℃, 335℃, 340℃, 350℃, or any combination thereof. The pressure of the second hydrogenation treatment is 3-5 MPa, for example, including but not limited to 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, or any combination thereof.

[0062] Through extensive and innovative experiments, the inventors discovered that when the yield of the fraction distilled from the oil slurry below 450℃ is ≥80%, performing the first and second hydrogenation treatments within the aforementioned parameter range can better achieve denitrification and desulfurization, improving the utilization rate of the oil slurry. This is because the oil slurry is rich in aromatics and sulfur- and nitrogen-containing heteroatoms, with π-π conjugation and hydrogen bonding forces between molecules, resulting in strong intermolecular forces and the formation of large molecular aggregates that encapsulate some S and N heteroatom compounds. Using this two-stage hydrogenation method, the first hydrogenation treatment, under the dual action of hydrogenation and heating, removes sulfur and nitrogen from free molecules and the surface of aggregates, causing the aggregates to "depolymerize" and decompose into free compounds, allowing the sulfur and nitrogen compounds to be fully exposed on the catalyst. During the second hydrogenation treatment, the exposed sulfur and nitrogen compounds can be more fully removed by hydrogenation.

[0063] Furthermore, in a specific embodiment of this application, the yield of the fraction in the oil slurry with a distillation temperature below 450°C is <80%, and the target fraction includes light fraction and heavy fraction; the cut-off temperature between the light fraction and the heavy fraction is 400-480°C; in step 4), the light fraction undergoes a first hydrogenation treatment, and the heavy fraction undergoes a second hydrogenation treatment; the temperature of the first hydrogenation treatment is 300-330°C, and the pressure is 2-4 MPa; the temperature of the second hydrogenation treatment is 340-380°C, and the pressure is 4-8 MPa.

[0064] Specifically, the yield of the fraction in the oil slurry with a distillation temperature below 450℃ is <80%. In step 3), during vacuum distillation, the target fraction includes light and heavy fractions. The cut-off temperature between the light and heavy fractions is 400-480℃.

[0065] In step 4), the light fraction is subjected to a first hydrogenation treatment. The temperature of the first hydrogenation treatment includes, but is not limited to, 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, or any combination thereof. The pressure of the first hydrogenation treatment includes, but is not limited to, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, or any combination thereof.

[0066] The heavy fraction is subjected to a second hydrogenation treatment. The temperature of the second hydrogenation treatment includes, but is not limited to, 340°C, 345°C, 350°C, 355°C, 360°C, 365°C, 370°C, 375°C, 380°C, or any combination thereof. The pressure of the second hydrogenation treatment includes, but is not limited to, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, or any combination thereof.

[0067] Through extensive creative experiments, the inventors discovered that when the oil slurry is at 450℃ and atmospheric pressure, and the process distillation rate is <80%, performing a first hydrogenation treatment on the light fraction and a second hydrogenation treatment on the heavy fraction according to the above parameter range can better achieve denitrification and desulfurization, and improve the utilization rate of the oil slurry. This is because, on the one hand, the above parameter range can play a role in chemical depolymerization; on the other hand, for heavy oil slurry with a low content of IBP-450℃ fraction, there are some aromatics with relatively higher ring numbers and sulfur and nitrogen-containing compounds in the oil slurry. By controlling the temperature and pressure of the first and second hydrogenation treatments, while removing sulfur and nitrogen compounds, the polycyclic aromatic hydrocarbons can be moderately ring-opened, thus becoming lighter and forming a more ideal aromatic structure.

[0068] Furthermore, in one specific embodiment of this application, the boiling point of the organic polar solvent is X℃, and the cutting temperature of the second recycled solvent is the AET temperature (AET refers to the actual boiling point temperature corresponding to the cutting temperature under a specific vacuum) Y℃, satisfying Y=X+(0℃~10℃).

[0069] In detail, the cutting temperature of the second recovered solvent refers to the temperature set during the vacuum distillation process in step 3).

[0070] The cutting temperature of the second recycled solvent is Y, for example, Y includes, but is not limited to, X℃, (X+2)℃, (X+4)℃, (X+6)℃, (X+8)℃, (X+10)℃ or any combination thereof.

[0071] When the cutting temperature of the second recycled solvent meets the above range, it can not only ensure the recovery of organic polar solvents, but also prevent the separation of effective components in the residual components, thereby further ensuring the utilization rate of the slurry.

[0072] Furthermore, in one specific embodiment of this application, the content of solid particles in the extraction phase is not higher than 150 ppm; and / or, the content of solid particles in the residual component is not higher than 50 ppm; and / or, the target fraction includes residual organic polar solvent, the mass ratio of residual organic polar solvent to organic polar solvent is N, and N≤15%.

[0073] In this application, solid particles refer to catalyst powder.

[0074] This application does not limit the method of controlling the content of solid particles in the extraction phase, the content of solid particles in the residual components, and the content of residual organic polar solvents.

[0075] When the content of solid particles in the extraction phase, the content of solid particles in the residual components, and the mass ratio of residual organic polar solvents meet the above ranges, deep desolidification and impurity removal can be better achieved, ensuring the utilization rate of the oil slurry.

[0076] Furthermore, in one specific embodiment of this application, the organic polar solvent includes at least one of sulfur atoms, nitrogen atoms, and oxygen atoms, and the number of sulfur atoms, nitrogen atoms, and oxygen atoms is independently 1-2; the molecular weight of the organic polar solvent is less than 100.

[0077] Furthermore, in one specific embodiment of this application, the organic polar solvent includes at least one of NMP, DMF, furfural, phenol, and DMSO.

[0078] The aforementioned types of organic polar solvents have high polarity, which can better release catalyst powders encapsulated by polar substances such as gums and asphaltenes. By combining them with filtration processes, gradient and deep removal of solid particles can be achieved.

[0079] Furthermore, the mass ratio of the organic polar solvent to the oil slurry is (0.5-3):1, and the extraction temperature is 20-130℃.

[0080] In detail, the mass ratio of the organic polar solvent to the oil slurry includes, but is not limited to, 0.5:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3:1, or any combination thereof.

[0081] The extraction temperature includes, but is not limited to, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or any combination thereof.

[0082] When the mass ratio of organic polar solvent to oil slurry and the extraction temperature meet the above ranges, the extraction efficiency can be improved while ensuring the stability of organic polar solvent extraction.

[0083] Furthermore, in one specific embodiment of this application, the first hydrogenation treatment and the second hydrogenation treatment also independently include a catalyst, wherein the active component of the catalyst is selected from at least one of Group VIB and Group VIII; the mass percentage of the active component in the catalyst is ≥1.0%.

[0084] In detail, the active components of the catalyst include, but are not limited to, at least one of molybdenum, cobalt, nickel, tungsten, iron, palladium, platinum, and rhodium.

[0085] It is understood that the catalyst includes a support, which is a porous material, including but not limited to at least one of aluminum oxide, silicon oxide, zirconium oxide, titanium oxide, Y-type molecular sieve, ZSM-5 molecular sieve, β molecular sieve, mordenite molecular sieve, and a mixture of metal or non-metal oxides and molecular sieves.

[0086] When the active component accounts for ≥1.0% of the mass of the catalyst, it can be ensured that the catalyst contains sufficient active components to ensure the effective catalytic reaction.

[0087] Furthermore, in one specific embodiment of this application, the active component of the first hydrogenation-treated catalyst includes at least one of W, Co, Mo, and Ni, and the active component of the second hydrogenation-treated catalyst includes at least one of Co, Mo, Ni, Pt, Pd, and Fe.

[0088] The catalyst type for the first hydrogenation treatment is a catalyst with selective depurification function, while the catalyst type for the second hydrogenation treatment is a catalyst with moderate hydrocracking function.

[0089] When the catalysts for the first and second hydrogenation treatments are selected from the above types, the first hydrogenation treatment focuses on selective desulfurization and "chemical depolymerization," selecting active components that are beneficial to desulfurization; the second stage involves further desulfurization, nitrogen removal, and partial saturated ring opening of polycyclic aromatic hydrocarbons, so active components that are beneficial to desulfurization, nitrogen removal, and hydrogenation are selected.

[0090] The method for oil slurry pretreatment provided in this application is described in detail below through specific embodiments.

[0091] Example 1

[0092] The oil slurry used in this embodiment is a high-sulfur heavy oil slurry. The oil slurry pretreatment method provided in this embodiment includes the following steps:

[0093] 1. Furfural was used as the organic polar solvent, with a mass ratio of organic polar solvent to oil slurry of 1.5:1. The oil slurry and furfural entered the extraction tower from the bottom and top of the tower, respectively, and the extraction temperature was 90℃. After extraction, the raffinate phase containing solid impurities and the extract phase containing the target product were separated and exited the extraction tower from the top and bottom, respectively.

[0094] 2. The extracted phase is processed by a flash evaporation unit to separate 85% of the solvent, which is then returned to the extraction unit as the first recovered solvent and used as a raw material for organic polar solvents. The remaining oil slurry after flash evaporation is filtered by a dead-end filtration unit to obtain the residual components.

[0095] 3. The residual components enter the vacuum distillation unit, where 420°C is used as the cut-off temperature for the light and heavy fractions to obtain the second recovered solvent and the light and heavy fractions. The second recovered solvent is returned to the extraction unit for use as a raw material for organic polar solvents.

[0096] 4. The light and heavy fractions undergo a first and second hydrogenation treatment, respectively, in a reactor. A single hydrogenation catalyst is loaded in two sections, upper and lower. The light and heavy fractions enter the reactor from the top of the upper and lower catalyst beds, respectively, and exit from the bottom of the upper and lower catalyst beds, respectively. The temperature for the first hydrogenation treatment is 300℃, and the temperature for the second hydrogenation treatment is 380℃, both at a pressure of 4 MPa. The liquid products after hydrogenation are combined to obtain a refined oil slurry.

[0097] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry has a light fraction cumulative yield of 65% at an AET temperature of 450°C, a solid particulate content of 121 ppm in the extraction phase, a solid particulate content of 50 ppm in the residual components, and a solvent content of 10% of the total added solvent.

[0098] Example 2

[0099] The oil slurry processed in this embodiment is the same as that in Embodiment 1. The oil slurry pretreatment method provided in this embodiment is basically the same as that in Embodiment 1, except that:

[0100] In step 4), the second recovered solvent is returned to the extraction unit as an organic polar solvent feedstock. The light and heavy fractions undergo a first hydrogenation treatment and a second hydrogenation treatment, respectively, in the first and second reactors. The catalyst in the first reactor is a single-stage hydrogenation catalyst, and the catalyst in the second reactor is a two-stage hydrogenation catalyst. The light and heavy fractions enter the reactor from the top of the upper and lower catalyst beds, respectively, and exit the reactor from the bottom of the bed. The temperature of the first hydrogenation treatment is 320°C and the pressure is 3 MPa; the temperature of the second hydrogenation treatment is 360°C and the pressure is 6 MPa. The liquid products after hydrogenation are combined to obtain a refined oil slurry.

[0101] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. The slurry used in this embodiment is at 450°C, the cumulative yield of light fraction is 65%, the content of solid particles in the extraction phase is 121 ppm, the content of solid particles in the residual components is 40 ppm, and the solvent content accounts for 10% of the total amount of solvent added.

[0102] Example 3

[0103] The oil slurry processed in this embodiment is a high-ash, high-sulfur oil slurry. The oil slurry pretreatment method provided in this embodiment includes the following steps:

[0104] 1. Furfural was used as the organic polar solvent, with a mass ratio of organic polar solvent to oil slurry of 1.5:1. The oil slurry and furfural entered the extraction tower from the bottom and top of the tower, respectively, and the extraction temperature was 90℃. After extraction, the raffinate phase containing solid impurities and the extract phase containing the target product were separated and exited the extraction tower from the top and bottom, respectively.

[0105] 2. The extracted phase is processed by a flash evaporation unit to separate 85% of the solvent, which is then returned to the extraction unit as the first recovered solvent and used as a raw material for organic polar solvents. The remaining oil slurry after flash evaporation is filtered by a cross-flow membrane filtration unit to obtain the residual components.

[0106] 3. The residual components enter the vacuum distillation unit, where 450°C is used as the cut-off temperature for the light and heavy fractions to obtain the second recovered solvent and the light and heavy fractions. The second recovered solvent is returned to the extraction unit for use as a raw material for organic polar solvents.

[0107] 4. The second recovered solvent is returned to the extraction unit as a feedstock for organic polar solvents. The light and heavy fractions undergo a first and second hydrogenation treatment in the same reactor. The upper and lower sections of the reactor are respectively packed with a first-stage hydrogenation catalyst and a second-stage hydrogenation catalyst. The light and heavy fractions enter the reactor from the top of the upper and lower catalyst beds, respectively, and exit from the bottom of the beds. The temperature of the first hydrogenation treatment is 330℃ and the pressure is 2 MPa; the temperature of the second hydrogenation treatment is 340℃ and the pressure is 8 MPa. The liquid products after hydrogenation are combined to obtain a refined oil slurry.

[0108] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry has an AET temperature of 450°C, a cumulative yield of light fraction of 45%, a solid particulate content of 150 ppm in the extraction phase, a solid particulate content of 50 ppm in the residual component, and a solvent content of 15% of the total added solvent.

[0109] Example 4

[0110] The oil slurry processed in this embodiment is a high-sulfur, light oil slurry. The oil slurry pretreatment method provided in this embodiment includes the following steps:

[0111] 1. DMF is used as the organic polar solvent, and the mass ratio of organic polar solvent to oil slurry is 1.5:1. The oil slurry and DMF enter the extraction tower from the top and bottom of the tower, respectively. The extraction temperature is 80℃. After extraction, the raffinate phase containing solid impurities and the extract phase containing the target product are separated and exit the extraction tower from the top and bottom, respectively.

[0112] 2. The extracted phase is processed by the flash evaporation unit, and 90% of the solvent is separated and returned to the extraction unit as the first recovered solvent for use as a solvent feedstock. The remaining oil slurry after flash evaporation is filtered by the cross-flow membrane filtration unit to obtain the residual components.

[0113] 3. The residual components enter the vacuum distillation unit to obtain the second recovered solvent and the target fraction. The second recovered solvent is returned to the extraction unit for use as an organic polar solvent feedstock.

[0114] 4. The target fraction undergoes a first hydrotreating and a second hydrotreating process in a reactor. The reactor is loaded with a hydrotreating catalyst. The fraction oil enters from the top of the reactor and exits from the bottom. The reaction temperature for the first hydrotreating is 300°C and the pressure is 4 MPa. The reaction temperature for the second hydrotreating is 350°C and the pressure is 3 MPa.

[0115] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry has a process distillation rate of 85% at 450°C, a solid particulate content of 30 ppm in the extraction phase, a solid particulate content of 10 ppm in the residual components, and a solvent content of 5% of the total added solvent.

[0116] Example 5

[0117] The type of slurry treated in this embodiment is the same as that treated in Example 4. The method of slurry pretreatment in this embodiment is basically the same as that in Example 4, except that:

[0118] In step 1), DMF is replaced with NMP, the mass ratio of organic polar solvent to oil slurry is 2.5:1, and the extraction temperature is 30℃.

[0119] In step 4), the target fraction undergoes a first hydrotreating and a second hydrotreating in a reactor. The reactor is filled with a hydrotreating catalyst, and the fraction oil enters from the top of the reactor and exits from the bottom. The reaction temperature for the first hydrotreating is 320°C and the pressure is 3 MPa, while the reaction temperature for the second hydrotreating is 340°C and the pressure is 4 MPa.

[0120] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry has a process distillation rate of 85% at 450°C, a solid particulate content of 25 ppm in the extraction phase, a solid particulate content of 10 ppm in the residual components, and a solvent content of 10% of the total added solvent.

[0121] Example 6

[0122] The oil slurry treated in this embodiment is the same as that in Example 4. The oil slurry pretreatment method in this embodiment is basically the same as that in Example 4, except that:

[0123] In step 4), the temperature of the first hydrogenation treatment is 330°C and the pressure is 3MPa; the temperature of the second hydrogenation treatment is 360°C and the pressure is 6MPa.

[0124] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. The slurry used in this embodiment has a distillation rate of 85% at 450°C, a solid particulate content of 30 ppm in the extraction phase, a solid particulate content of 10 ppm in the residual components, and a solvent content of 5% of the total added solvent.

[0125] Example 7

[0126] The oil slurry processed in this embodiment is the same as that in Example 1. The oil slurry pretreatment method in this embodiment is basically the same as that in Example 1, except that:

[0127] In step 4), the temperature of the first hydrogenation treatment is 330°C and the pressure is 3MPa; the temperature of the second hydrogenation treatment is 320°C and the pressure is 3MPa.

[0128] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. In this embodiment, the slurry has a light fraction cumulative yield of 65% at an AET temperature of 450°C, a solid particulate content of 121 ppm in the extraction phase, a solid particulate content of 50 ppm in the residual components, and a solvent content of 10% of the total added solvent.

[0129] Example 8

[0130] The oil slurry processed in this embodiment is the same as that in Example 1. The oil slurry pretreatment method in this embodiment is basically the same as that in Example 1, except that:

[0131] In step 1), the mass ratio of organic polar solvent to oil slurry is 3.5:1, and the extraction temperature is 135℃.

[0132] The specific physical properties of the slurry and refined slurry in this embodiment are shown in Table 1. The slurry used in this embodiment has a distillation rate of 65% at 450°C, a solid particulate content of 225 ppm in the extraction phase, a solid particulate content of 50 ppm in the residual components, and a solvent content of 15% of the total added solvent.

[0133] Comparative Example 1

[0134] The oil slurry treated in this comparative example is the same as that in Example 3. The oil slurry pretreatment method provided in this comparative example is basically the same as that in Example 3, except that:

[0135] In step 4), the target fraction is hydrogenated in the reactor using a single hydrogenation catalyst. The hydrogenation temperature is 330°C and the pressure is 4.1 MPa. The liquid products after hydrogenation are combined to obtain refined oil slurry.

[0136] The specific physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 1.

[0137] Comparative Example 2

[0138] The type of oil slurry treated in this comparative example is the same as that in Comparative Example 1, and the oil slurry pretreatment method provided in this comparative example is basically the same as that in Comparative Example 1, with the following differences:

[0139] The target fraction is hydrogenated in the reactor using a single-stage hydrogenation catalyst. The hydrogenation temperature is 380°C and the pressure is 4.1 MPa. The liquid products after hydrogenation are combined to obtain a refined oil slurry.

[0140] The specific physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 1.

[0141] Table 1

[0142] As shown in Table 1, the oil slurry treatment method provided in this application can perform deep deconsolidation, deep impurity removal, and enrichment of 3- and 4-cyclic aromatic hydrocarbons on different types of oil slurries. Specifically, the methods provided in Examples 1-8 achieve a deashing rate of no less than 95%, a desulfurization rate of no less than 60%, a denitrification rate of no less than 6%, and a deasphalting rate of no less than 60%. Furthermore, they can enrich 3- and 4-cyclic aromatic hydrocarbons simultaneously with deep deconsolidation and deep impurity removal. A comparison of Example 3 with Comparative Examples 1 and 2 shows that, for the same type of oil slurry, the first and second hydrogenation treatments exhibit superior desulfurization and denitrification rates compared to a single hydrogenation treatment, and the content of 3- and 4-cyclic aromatic hydrocarbons is also significantly increased.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for pretreatment of oil slurry, wherein, Includes the following steps: 1) The oil slurry is extracted using an organic polar solvent to obtain a raffinate phase containing solid impurities and an extract phase containing the target product. 2) The extracted phase is subjected to flash evaporation and filtration sequentially to obtain the first recovered solvent and residual components including the target product; 3) The residual components are subjected to vacuum distillation to obtain a second recovered solvent and the target fraction; 4) The target fraction is subjected to a first hydrogenation treatment and a second hydrogenation treatment to obtain a refined oil slurry; The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa. The second hydrogenation treatment is carried out at a temperature of 320-380℃ and a pressure of 3-8MPa.

2. The method according to claim 1, wherein, The yield of the fraction in the oil slurry with a distillation temperature below 450°C is ≥80%, and the target product fraction is the total fraction of the oil slurry. In step 4), the target fraction is subjected to the first hydrogenation treatment and the second hydrogenation treatment in sequence; The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa; The second hydrogenation treatment is carried out at a temperature of 320-350℃ and a pressure of 3-5MPa.

3. The method according to claim 1, wherein, The yield of the fraction from the oil slurry with a distillation temperature below 450°C is <80%, and the target fraction includes light fraction and heavy fraction; the cut-off temperature between the light fraction and the heavy fraction is 400-480°C. In step 4), the light fraction undergoes a first hydrogenation treatment, and the heavy fraction undergoes a second hydrogenation treatment; The temperature of the first hydrogenation treatment is 300-330℃, and the pressure is 2-4MPa; The second hydrogenation treatment is carried out at a temperature of 340-380℃ and a pressure of 4-8MPa.

4. The method according to any one of claims 1-3, wherein, The content of solid particles in the extraction phase is not higher than 150 ppm.

5. The method according to claim 4, wherein, The content of solid particulate matter in the residual component is not higher than 50 ppm; The residual components include residual organic polar solvents, wherein the mass ratio of the residual organic polar solvents to the organic polar solvents is N, and N ≤ 15%.

6. The method according to any one of claims 1-3, wherein, The organic polar solvent includes at least one of sulfur atoms, nitrogen atoms, and oxygen atoms, and the number of each of the sulfur atoms, nitrogen atoms, and oxygen atoms is independently 1-2; the molecular weight of the organic polar solvent is less than 100.

7. The method according to claim 6, wherein, The organic polar solvent includes at least one of NMP, DMF, furfural, phenol, and DMSO.

8. The method according to any one of claims 1-3, wherein, The mass ratio of the organic polar solvent to the oil slurry is (0.5-3):1, and the extraction temperature is 20-130℃.

9. The method according to claim 8, wherein, The first hydrogenation treatment and the second hydrogenation treatment also independently include a catalyst, wherein the active component of the catalyst is selected from at least one of Group VIB and Group VIII; and the active component accounts for ≥1.0% of the mass of the catalyst.

10. The method according to claim 9, wherein, The active component of the first hydrogenation-treated catalyst includes at least one of W, Co, Mo, and Ni, and the active component of the second hydrogenation-treated catalyst includes at least one of Co, Mo, Ni, Pt, Pd, and Fe.

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