Method for solid removal from slurry oil, and method for solid removal and impurity removal from slurry oil

Abstract

A method for solid removal from slurry oil, and a method for solid removal and impurity removal from slurry oil. The method for solid removal from slurry oil comprises: (1) bringing an organic solvent in contact with a catalytic slurry oil to perform extraction, so as to obtain an upper raffinate phase 1 and a lower extract phase 1, wherein the mass ratio of the organic solvent to the catalytic slurry oil is not less than 0.5; and (2) removing solids and the organic solvent from the raffinate phase 1 to obtain a raffinate oil, and returning the removed organic solvent back to step (1) for extraction. The organic solvent is selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide and sulfolane. The method can achieve the combined effect of deep solid removal from the slurry oil and enrichment of aromatics in the slurry oil, and can effectively enhance the comprehensive utilization value of the slurry oil. The method avoids the technical problem of low utilization rate of the effective components in the slurry oil caused by some useful components of the slurry oil also being removed while removing solid particles. Thus, the method increases the operation cycle of the slurry-oil solid removal technique and reduces energy consumption, thereby facilitating the amelioration of the technical problem of large-scale industrial application.

Description

Oil slurry desolidification method and desolidification impurity removal method

[0001] Cross-reference to Related Applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411533930.3, filed October 30, 2024, Chinese Patent Application No. 202411740120.5, filed November 29, 2024, and Chinese Patent Application No. 202411740122.4, filed November 29, 2024, the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the technical field of petroleum processing, in particular to an oil slurry desolidification method and a desolidification impurity removal method. BACKGROUND

[0004] Catalytic cracking oil slurry is a byproduct of catalytic cracking processing, which contains a large amount of three and four ring aromatic hydrocarbons, and is an ideal component for preparing carbon material precursors. However, the solid particles in the oil slurry, such as catalyst powder, will affect its comprehensive utilization. Therefore, how to effectively remove the solid particles from the oil slurry and improve the comprehensive utilization value of the oil slurry is a problem to be solved in the current technical field of petroleum processing. The viscosity of the oil slurry system is large, especially the polar components of gum and asphaltene in it, which will form "inclusion bodies" with solid particles due to adsorption, increasing the difficulty of solid particle removal. The ash content in the oil slurry is high (2000-5000 ppm), and the solid content particle size distribution is wide (0.5-40.0 μm), making it difficult to deeply remove all solid particles in the range of particle size. The existing technology has the following limitations: (1) the shortcomings of single technology: there is no single technology that can effectively remove solid particles in such a wide particle size range; (2) loss of effective components: part of the useful oil slurry components will be removed together when removing solid particles, reducing the utilization rate of effective components; (3) running cycle and energy consumption problems: the running cycle is short, and the energy consumption is high, which is not conducive to large-scale industrial application.

[0005] The existing desolidification technologies mainly include two types of intermittent and continuous operation. The intermittent desolidification technologies mainly include filtration and sedimentation method in terms of technical principle. The filtration method is mainly suitable for the case where the solid particle content in the oil slurry is not too high, and can remove the solid particles within a certain particle size range, but the removal effect for smaller particles is limited. The particle size of the solid content that can be removed depends on the pore size of the filter medium, and generally larger particles can be removed. The sedimentation method can be used for preliminary separation of solid particles in the oil slurry, which is through the natural sedimentation of solid particles by gravity, but the sedimentation speed is slow and the desolidification effect is limited. The particle size range of the solid content that can be removed is: the effect is good for larger particles, but the effect on small particles is not obvious. In order to improve the desolidification effect, some strengthening means are developed in the industry, mainly including centrifugal, pressure filtration, centrifugal, electric field, magnetic field, etc. during the desolidification process, to strengthen the desolidification effect. Two or more combined technologies are also adopted to improve the filtration speed, efficiency and removal range of solid particles. The continuous desolidification technology includes cross-flow membrane filtration technology, electric field desolidification technology and supergravity assisted desolidification technology. But all have certain application limitations, such as cross-flow membrane filtration technology, which inevitably produces 10-20% concentrated oil slurry while obtaining clarified oil slurry, which is wasted without good utilization scene, electric field desolidification technology has limitations on the content of polar asphaltene in the oil slurry, and the operation cycle is greatly reduced for oil slurry with high asphaltene content, and the supergravity assisted desolidification technology needs to add flocculants for better effect, and the development of flocculants is also more difficult, and needs to be customized for different types of oil slurry.

[0006] Oil slurry desolidification technology is a key step in improving the comprehensive utilization value of petroleum processing by-products. Currently, although existing technologies have solved the problem of removing solid particles from oil slurry to some extent, many limitations remain. CN115505424A discloses a method for desolidifying catalytic oil slurry, including steps S1: mixing and heating the raw oil slurry with a diluent; step S2: vacuum dehydrating the mixture of raw oil slurry and diluent obtained in step S1; step S3: filtering the mixture obtained in step S2; and step S4: vacuum stripping distillation of the mixture obtained in step S3 to obtain desolidified oil slurry. This invention effectively dissolves a large amount of gum and asphaltenes in the catalytic oil slurry by adding a diluent, destroying the coating layer and interaction forces between the oil slurry and the catalyst powder. Furthermore, the diluent can dilute the catalytic oil slurry and reduce its viscosity, greatly reducing the difficulty of separating the oil and solid phases, effectively achieving desolidification of the catalytic oil slurry, and ensuring further processing of the catalytic oil slurry. This technology introduces new solid particles of clay to adsorb colloids and asphaltenes. After adsorption, these particles form a new encapsulation system, increasing the difficulty of deconsolidation. Subsequent filtration removes the solid particles; however, the specific filtration methods employed are not disclosed, making it impossible to assess the filtration effectiveness. CN111303939A provides a method and system for deconsolidating aromatic oil from catalytic slurry through vacuum distillation to produce needle coke feedstock. This method and system enable comprehensive utilization of the catalytic slurry. High-value aromatic oils are separated by vacuum distillation, and catalyst particles and metallic impurities are efficiently removed using a liquid-solid separator. The clarified oil after solidification has an ash content of no more than 100 ppm, and can even be reduced to below 10 ppm. The aromatic index (BMCI) is no less than 120, and impurities are low (sulfur mass fraction no more than 0.5%, total nitrogen mass fraction no more than 0.05%). All indicators fully meet the requirements for high-quality needle coke feedstock, enabling the regeneration of previously difficult-to-process and low-economic-value catalytic slurry into high-quality oil-based needle coke feedstock. This also lays the foundation for further development of other high-value comprehensive utilization pathways for catalytic slurry, providing a new solution for the disposal of catalytic slurry by petroleum refining enterprises, and significantly improving the economic benefits of related refining and chemical industry chain enterprises. The main problems with this technology are low slurry utilization rate and the inability to truly enrich aromatics due to the close boiling points of aromatics and some saturated hydrocarbons, as boiling point cutting methods cannot achieve true aromatic enrichment.

[0007] The future development direction of oil slurry desolidification technology mainly has three aspects: First, developing new composite technologies that combine different types of desolidification technologies with other oil slurry treatment technologies. Through synergistic effects and optimized process parameters, this can achieve a wider range of solid particle size distributions and greater removal depth. Second, improving the utilization rate of effective components while removing solid particles and minimizing the loss of useful oil slurry components. This can be achieved by further processing the removed solid particles to recover useful components and improve resource utilization. Third, extending the operating cycle and reducing energy consumption. This can be achieved by optimizing equipment design and operating conditions, leveraging the strengths and mitigating the weaknesses of different technologies, and working synergistically to reduce equipment blockage and wear, thereby extending the operating cycle. Summary of the Invention

[0008] The purpose of this invention is to provide a method for desolidifying and removing impurities from oil slurry. The oil slurry desolidification method of this invention can achieve a comprehensive effect of deep desolidification and enrichment of aromatics in the oil slurry, effectively improving the comprehensive utilization value of the oil slurry. It avoids the technical problem that some useful oil slurry components are also removed while removing solid particles, resulting in low utilization rate of effective components in the oil slurry. It also improves the operating cycle of the oil slurry desolidification technology, reduces energy consumption, and is conducive to large-scale industrial applications.

[0009] The present invention provides a first aspect of a method for deconsolidating oil slurry, the method comprising:

[0010] (1) Extraction is performed by contacting an organic solvent with a catalytic oil slurry to obtain an upper raffinate phase 1 and a lower extract phase 1, wherein the mass ratio of the organic solvent to the catalytic oil slurry is not less than 0.5;

[0011] (2) After removing solids and organic solvents from raffinate phase 1, raffinate oil is obtained. The removed organic solvents are returned to step (1) for extraction. The organic solvents are selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide and sulfolane.

[0012] A second aspect of the present invention provides a method for removing solids and impurities from oil slurry, the method comprising:

[0013] Step 1: Separate the catalytic oil slurry into light components and heavy components according to temperature;

[0014] Step 2: Selectively hydrogenate the light components according to their sulfur content;

[0015] Step 3: The catalytic oil slurry heavy components are mixed with an organic solvent to form a mixed heavy component. The organic solvent is selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide, and sulfolane.

[0016] Step 4: Filter and settle the mixed heavy components to obtain a permeate side component and a concentration side component. Mix the concentration side component with the heavy components and an organic solvent. Remove the solvent from the permeate side component to obtain the filtered slurry heavy components. Hydrogenate the filtered slurry heavy components to obtain hydrogenated slurry heavy components. Complete the selective deconsolidation and impurity removal pretreatment of the slurry.

[0017] Compared with existing technologies, the beneficial effects of the technical solution of this invention are as follows:

[0018] 1. Deep Desolidification: This technical solution achieves deep desolidification of solids in the slurry through a combined process. The slurry treatment process only removes catalyst powder, without other byproducts, thus improving the comprehensive utilization value of the slurry. 2. Increased Processing Capacity and Operating Cycle: Adding an extraction process before desolidification removes fine particles that can affect the long-term operation of filtration technologies, including cross-flow membrane filtration, thereby increasing the processing capacity of the unit filtration area, achieving energy saving and consumption reduction, and extending the operating cycle of the desolidification unit. 3. Optimized Equipment Use: For cross-flow membrane filtration units, since the overall solid content is reduced and consists mainly of large-diameter catalyst particles, large-pore-rate, high-flux membrane tubes can be used to increase the clarified slurry utilization rate, reduce the circulation volume and the proportion of concentrated slurry; and the membrane flux decreases less during operation, extending the membrane tube lifespan. 4. Improved Product Quality: After the extraction process, aromatics are enriched, improving the comprehensive utilization value of the slurry. The final deep-desolidified and aromatic-enriched refined slurry can be used as a raw material for the production of needle coke and mesophase pitch. 5. Broad Application Prospects: This technical solution can be used to process oil slurry from different sources, and is particularly suitable for processing intermediate-based and paraffin-based oil slurry feedstocks to obtain deeply deconsolidated and aromatic-enriched oil slurry, which can be used to produce high-quality needle coke and mesophase pitch. With the booming development of the carbon materials field using oil slurry as the main raw material, this technology has outstanding technical and economic advantages and very good application prospects.

[0019] The oil slurry deconsolidation and impurity removal method of this invention can target and deeply deconsolidate and remove impurities from different types of oil slurries, obtaining high-quality aromatic-rich components with a relatively concentrated molecular weight distribution, which can be used as raw materials for the preparation of high-quality mesophase asphalt and / or needle coke. Beneficial effects include: 1. Highly targeted and energy-saving: The pretreatment method provided by this invention separates the oil slurry into light and heavy components based on the distribution characteristics of various compounds and solid contents during oil slurry distillation, and performs targeted treatment on each, greatly improving the efficiency and effect of deconsolidation and impurity removal. The treatment method is simple and energy-efficient, significantly reducing processing costs compared to existing technologies, achieving energy saving and consumption reduction. 2. High-quality oil slurry and high utilization rate: The pretreatment method provided by this invention, through the introduction of organic solvents for physical depolymerization and selective hydrogenation, selectively hydrogenates and desulfurizes the light components, deeply hydrogenates the heavy components, and moderately saturates the aromatics, effectively reducing the sulfur, nitrogen, and aromatic content in the oil slurry. Besides solid particles, there are no other byproducts, resulting in high-quality oil slurry and high comprehensive utilization rate. 3. Strong adaptability: The pretreatment method of this invention is particularly suitable for treating heavy oil slurries with high sulfur and nitrogen content, exhibiting strong adaptability and meeting the treatment needs of different types of oil slurries. 4. The pretreatment method provided by this invention can serve as a universally applicable pretreatment process for high-sulfur oil slurries. Through a combination of vacuum cutting, heavy component filtration and solidification, and hydrogenation process unit technologies, this method can achieve tailored deep solidification and deep impurity removal for oil slurries with different properties, compositions, and sources, obtaining high-quality aromatic-rich components with a relatively concentrated molecular weight distribution, which can be used as raw materials for the preparation of high-quality mesophase pitch and / or needle coke. Attached Figure Description

[0020] Figure 1 is a flowchart of the extraction-desolidification combined technology for subsequent recovery;

[0021] Figure 2 is a flowchart of the extraction-desolidification combined technology with recovery preceding solidification.

[0022] Figure 3 is a process flow diagram of the membrane separation technology.

[0023] Figure 4 is a schematic diagram of the oil slurry selective deconsolidation and impurity removal pretreatment system according to an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the structure of a selective deconsolidation and impurity removal pretreatment system for oil slurry according to another embodiment of the present invention.

[0025] Symbol explanation: Distillation unit 1, Mixing unit 2, Filtration unit 3, Sedimentation unit 4, Flash evaporation unit 5, Light component hydrogenation unit 6, Heavy component hydrogenation unit 7. Detailed Implementation

[0026] The present invention provides a first aspect of a method for deconsolidating oil slurry, the method comprising:

[0027] (1) Extraction is performed by contacting an organic solvent with a catalytic oil slurry to obtain an upper raffinate phase 1 and a lower extract phase 1, wherein the mass ratio of the organic solvent to the catalytic oil slurry is not less than 0.5;

[0028] (2) After removing solids and organic solvents from raffinate phase 1, raffinate oil is obtained. The removed organic solvents are returned to step (1) for extraction. The organic solvents are selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide and sulfolane.

[0029] According to a preferred embodiment of the present invention, the mass ratio of the organic solvent to the catalytic slurry is (0.5-3):1, for example, 1:1, 1.3:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1, etc. By employing the aforementioned technical solution, the present invention can achieve both aromatic hydrocarbon enrichment and solid removal in the slurry, while maintaining a low energy consumption during operation.

[0030] In this invention, after extraction of the catalytic oil slurry and organic solvent, an upper raffinate phase 1 and a lower extract phase 1 are obtained. The raffinate phase 1, carrying most of the solid particles, overflows from the top of the extraction device and enters the desolidification device. After sedimentation and desolidification, the raffinate oil overflows from the top of the desolidification device.

[0031] In this invention, the destination of the raffinate oil can be determined according to the different compositions of the saturated components in the slurry. For example, when the saturated components in the slurry are mainly alkanes, the raffinate oil is returned to the catalytic cracking unit for reprocessing after the organic solvents are removed by stripping distillation or vacuum distillation. When the saturated components in the slurry are mainly cycloalkanes, the raffinate oil is mixed with extraction phase 1 for subsequent processing.

[0032] According to a preferred embodiment of the present invention, when the mass ratio of the organic solvent to the catalytic slurry is not higher than 1:1, the step of obtaining an aromatic-enriched desoldered slurry after removing solids and organic solvent from the extraction phase 1 includes: removing solids from the extraction phase 1 to obtain the extraction phase 2, removing organic solvents from the extraction phase 2 to obtain the aromatic-enriched desoldered slurry, and returning the organic solvent removed from the extraction phase 2 to the extraction tower for reuse.

[0033] According to a preferred embodiment of the present invention, when the mass ratio of the organic solvent to the catalytic slurry is not higher than 1:1, the operating system of the present invention includes: an extraction unit, a desolidification unit A, a desolidification unit B, and a recovery unit. Specifically, the catalytic slurry enters the extraction unit for extraction to obtain raffinate phase 1 and extractable phase 1. Raffinate phase 1 enters the desolidification unit A to obtain upper raffinate oil, lower organic solvent, and solid-rich components. The lower organic solvent is returned to the extraction unit for reuse. Extractable phase 1 enters the desolidification unit B for desolidification to obtain extractable phase 2 and solid particles. Extractable phase 2 enters the recovery unit to remove organic solvent to obtain aromatic-enriched and deeply desolidified slurry. The removed organic solvent is returned to the extraction unit for reuse.

[0034] According to a preferred embodiment of the present invention, when the mass ratio of organic solvent to catalytic slurry is higher than 1:1, the step of obtaining aromatic-enriched desoldered slurry after removing solids and organic solvent from extraction phase 1 includes: removing organic solvent from extraction phase 1 to obtain extraction phase 3, removing solids from extraction phase 3, and then removing organic solvent to obtain aromatic-enriched desoldered slurry, and returning the organic solvent removed from extraction phase 1 to the extraction tower for reuse.

[0035] According to a preferred embodiment of the present invention, when the mass ratio of the organic solvent to the catalytic slurry is higher than 1:1, the operating system of the present invention includes: an extraction unit, a desolidification unit A, a recovery unit A, a desolidification unit B, and a recovery unit B. Specifically, the catalytic slurry enters the extraction unit for extraction to obtain raffinate phase 1 and extract phase 1. Raffinate phase 1 enters the desolidification unit A for desolidification to obtain an upper raffinate oil, a lower organic solvent, and a solid-rich component. The lower organic solvent is returned to the extraction unit for reuse. Extract phase 1 enters the recovery unit A to remove the organic solvent to obtain extract phase 3. The removed organic solvent is returned to the extraction unit for reuse. Extract phase 3 enters the desolidification unit B to remove solid particles, and then enters the recovery unit B for further removal of organic solvent to obtain an aromatic-enriched and deeply desolidified slurry. The removed organic solvent is returned to the extraction unit for reuse.

[0036] In this invention, after the extraction phase 3 is desolidified, the removed portion concentrates the residual aromatic components containing organic solvents in the catalyst powder of the extraction phase 3, which can be returned to the catalytic slurry for re-extraction.

[0037] In this invention, after catalytic oil slurry extraction, the organic solvent is first removed, resulting in an extract phase 3 with a viscosity of 1-150 mm. 2 The aforementioned technical solution is more conducive to subsequent detachment.

[0038] In this invention, there are no special limitations on the equipment or apparatus used for the extraction process. For example, it can be carried out in an extraction tower. There are no special requirements for the internal structure of the extraction tower. For example, the extraction tower can have static or dynamic internal components. Static internal components can be a turntable and / or a sieve plate, and dynamic internal components can be a vibrating sieve plate and / or a turbine.

[0039] In this invention, the extraction temperature can be selected over a wide range. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the extraction temperature is 25-130°C.

[0040] In this invention, there are no special requirements for the extraction time. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the extraction time is 10-60 min.

[0041] In this invention, there are no special requirements for the contact method during the extraction process. According to a preferred embodiment of the invention, the contact method for extraction is countercurrent contact. The inlet positions of the oil slurry and the organic solvent are determined by their densities. The denser fluid enters from the upper side of the extraction tower, while the less dense fluid enters from the lower side of the tower, achieving countercurrent contact within the tower. During this process, the organic solvent breaks down the inclusions formed by the asphaltenes and catalyst powder due to polar adsorption, releasing the catalyst powder. The raffinate phase 1, which has low solubility with the organic solvent, has a low density and is distributed in the upper layer, but has a high viscosity, trapping most of the catalyst powder in the oil slurry, especially small particles. A small number of larger particles settle into the lower extraction phase 1.

[0042] According to a preferred embodiment of the present invention, the desolidation temperature of the raffinate phase 1 is lower than the extraction temperature, and more preferably, the desolidation temperature of the raffinate phase 1 is 0-60°C. Since the desolidation temperature of the raffinate phase 1 is lower than the extraction temperature, it will further release the saturated components dissolved therein at high temperatures. Because the density of the catalyst powder is comparable to that of the oil slurry, which is greater than that of the mixture of the saturated components and a small amount of solvent, it can quickly separate into layers, with the catalyst distributed at the bottom of the tank.

[0043] In this invention, no special requirements are placed on the equipment for removing solids and organic solvents from the raffinate phase 1. According to a preferred embodiment of the invention, the solidification of the raffinate phase 1 is carried out in a settling separator with a narrowed bottom diameter. The advantages of this invention are illustrated in the embodiment using a settling tank with a narrowed bottom diameter. The settling separator with a narrowed bottom diameter facilitates the release of the catalyst powder that accelerates settling. Simultaneously, a differential pressure level gauge can be used to control the interface, automatically opening the bottom valve based on the density difference to release the catalyst powder settling at the bottom of the separator.

[0044] In this invention, there are no special requirements for the deconsolidation time of the raffinate phase 1. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the deconsolidation time of the raffinate phase 1 is 2-8 hours.

[0045] In this invention, there is no special limitation on the position where the raffinate phase 1 enters the settling separator; for example, it can enter from the middle of the settling separator.

[0046] In this invention, there are no particular limitations on the method for removing solids from the extraction phase 1. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the method for removing solids from the extraction phase 1 is selected from cross-flow membrane filtration, dead-end filtration, and settling. From the perspective of solid removal effect, cross-flow membrane filtration is more effective; from an economic perspective, dead-end filtration or settling is better. After organic solvent depolymerization and extraction, most of the catalyst powder overflows from the top of the column and separates. A small amount of catalyst powder with larger particle size, due to its high density, is distributed in the extraction phase 1 and moves towards the bottom of the column. After settling, it easily settles to the bottom.

[0047] In this invention, when the extraction phase 1 removes solids using a cross-flow membrane filtration system, the pore size of the cross-flow membrane filtration system is selected based on the particle size of the catalyst powder in the extraction phase 1. According to a preferred embodiment of the invention, the pore size of the cross-flow membrane filtration system is 0.1-50 μm. Further, the particle size of the catalyst powder in the extraction phase 1 depends on the saturation content of the oil slurry. If the oil slurry is of medium to low saturation content, the resulting upper raffinate phase 1 has a moderate content and a moderate carrying capacity for solid particles in the oil slurry. A small portion of smaller particles will settle into the extraction phase 1 and need to be separated in subsequent processes, requiring the use of a membrane with a smaller pore size for separation. If the oil slurry is of high saturation content, the resulting upper raffinate phase 1 has a higher content and a higher carrying capacity for solid particles in the oil slurry. Almost no smaller particles will settle into the extraction phase 1, and the larger particles that need to be separated in subsequent processes will require the use of a membrane with a larger pore size for separation.

[0048] In this invention, there are no special requirements for the method of removing organic solvent from extraction phase 1. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the method of removing organic solvent from extraction phase 1 is selected from one or more of flash evaporation, vacuum distillation, stripping distillation, and molecular distillation. In this embodiment, flash evaporation is used as the method of removing organic solvent to illustrate the advantages of the invention.

[0049] According to a preferred embodiment of the present invention, the density of the organic solvent is less than the density of the oil slurry, and more preferably, the density is between the densities of the saturated and aromatic components in the oil slurry. Using the aforementioned technical solution, better extraction can be achieved. After the oil slurry comes into contact with the solvent, it releases the saturated components with low solubility and low density, which carry solid particles to the top of the column, while the aromatic components, colloids, and asphaltenes with high density and high polarity dissolved in the oil slurry are carried to the bottom of the column. During the upward movement of the raffinate phase, it comes into countercurrent contact with the fresh organic solvent again, dissolving the small amount of aromatic components carried therein and moving them to the bottom of the column, thus improving the selectivity of the extraction.

[0050] In this invention, there are no special requirements for the components and contents of the catalytic slurry. The following is an example description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the catalytic slurry contains, by weight: 15-65% saturated components, 25-65% aromatic components, 8-20% gum, and 1-8% asphaltenes.

[0051] The technical solution of the present invention can achieve the desolidification treatment of catalytic oil slurry with different solid contents, and can achieve the desolidification effect. There are no special requirements for the solid content of the catalytic oil slurry. The following is an example, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, the solid content of the catalytic oil slurry is 1500-5000ppm.

[0052] According to a preferred embodiment of the present invention, the catalytic slurry further includes membrane separation before contact with the organic solvent, comprising: performing membrane separation on the slurry raw material to obtain a clarified slurry and a concentrated catalytic slurry, wherein the pore size of the membrane is less than 0.2 μm; the concentrated catalytic slurry is desolidified according to the slurry desolidification method of the present invention, wherein the organic solvent is removed from the extraction phase 1, the organic solvent and the extracted oil are separated, the removed organic solvent is returned to step (1) for extraction, and the extracted oil is returned to the membrane separation step. The combination of membrane filtration desolidification and extraction units has the following beneficial effects: 1. It can effectively remove solids with a wide range of particle sizes from the slurry, achieving deep desolidification; 2. The filtration unit does not need to pursue excessively high clarified slurry recovery rates, thereby reducing the circulation ratio and time, and improving the overall desolidification efficiency; 3. After separation of the slurry raw materials, the concentrated slurry is extracted to remove solids and saturated components, and then returned to the filtration unit to become clarified slurry, with no concentrated slurry produced throughout the process; 4. The solid catalyst particles and saturated components after extraction can be recycled into the catalytic cracking unit, solving their disposal problem; 5. Overall, the deep desolidification process of the slurry produces no concentrated slurry, realizing comprehensive utilization of all components of the slurry, and the desolidification process is energy-saving and consumption-reducing, with a long operating cycle.

[0053] According to a preferred embodiment of the present invention, in step (1), the pore size of the membrane is 0.1-0.2 μm, for example, 0.12 μm, 0.14 μm, 0.16 μm, 0.18 μm, etc. The aforementioned technical solution has the advantages of ensuring that the particle size distribution in the clarified oil slurry passing through the membrane pores meets product requirements, while preventing excessively low oil slurry permeability due to excessively small pore size, thereby reducing the throughput of the extraction unit and the energy consumption of the entire process system.

[0054] In this invention, there are no special requirements for the single-pass throughput of the clarified oil slurry. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the single-pass throughput of the clarified oil slurry is 70-90%, for example, 72%, 75%, 78%, 80%, 82%, 85%, 88%, etc.

[0055] In this invention, there are no special restrictions on the specific control method for controlling the single-pass throughput of the clarified slurry. For example, it can be controlled by adjusting the pressure, which is well known to those skilled in the art and will not be elaborated here.

[0056] In this invention, no special requirements are made for the specific method of membrane filtration. For example, cross-flow membrane filtration can be used for membrane filtration.

[0057] In this invention, there are no special requirements for the solid content of the oil slurry raw material being processed. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the solid content of the oil slurry raw material is 1800-6000 ppm.

[0058] In this invention, there are no special requirements for the content of each component in the oil slurry raw material. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, the oil slurry raw material contains, by weight: 15-65% saturated components, 25-65% aromatic components, 8-20% gum, and 1-8% asphaltene.

[0059] In this invention, the destination of the raffinate phase can be handled differently depending on the composition and structure of the saturated fractions in the concentrated slurry. The following is an illustrative description, but it does not limit the scope of the invention. According to a preferred embodiment of the invention, when the saturated fractions in the concentrated slurry are mainly alkanes, the raffinate phase is returned to the catalytic cracking unit for reprocessing by stripping distillation or vacuum distillation; when the saturated fractions in the concentrated slurry are mainly cycloalkanes, the raffinate phase is mixed with the extracted phase for subsequent processing.

[0060] A second aspect of the present invention provides a method for removing solids and impurities from oil slurry, the method comprising:

[0061] Step 1: Separate the catalytic oil slurry into light components and heavy components according to temperature;

[0062] Step 2: Selectively hydrogenate the light components according to their sulfur content;

[0063] Step 3: The catalytic oil slurry heavy components are mixed with an organic solvent to form a mixed heavy component. The organic solvent is selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide, and sulfolane.

[0064] Step 4: Filter and settle the mixed heavy components to obtain a permeate side component and a concentration side component. Mix the concentration side component with the heavy components and an organic solvent. Remove the solvent from the permeate side component to obtain the filtered slurry heavy components. Hydrogenate the filtered slurry heavy components to obtain hydrogenated slurry heavy components. Complete the selective deconsolidation and impurity removal pretreatment of the slurry.

[0065] In step 1 of the above method, the oil slurry used as raw material can be a catalytic oil slurry. Catalytic oil slurry has a complex composition; besides solid particles, if classified according to the four components of petroleum, its main components can be alkanes, aromatics, gums, and asphaltenes. Sulfides are distributed in alkanes, aromatics, gums, and asphaltenes, while nitrogen compounds are mainly distributed in gums and asphaltenes. If classified according to the type of elements in the compounds, they can be divided into hydrocarbons containing only carbon and hydrogen, and non-hydrocarbons containing sulfur, nitrogen, oxygen, and metal heteroatoms. Hydrocarbons, especially aromatics with a narrow ring number distribution range, are ideal components in oil slurry.

[0066] In step 1 of the above method, the process of separating the oil slurry into light and heavy components based on temperature is based on the distribution characteristics of various compounds and solids during the oil slurry distillation process. The light components have low sulfur and nitrogen content, low aromatic hydrocarbon density, and do not contain gum, asphaltenes, or solid particles. The heavy components have high aromatic hydrocarbon density and are enriched in sulfur, nitrogen, gum, asphaltenes, and solid particles. By separating the oil slurry into two components, the energy consumption and cost of subsequent processing can be effectively reduced, and processing efficiency can be improved.

[0067] In the above method, step 1, the separation can be achieved by distillation, and the separation is based on a temperature of 400-480℃. The specific temperature can be adjusted according to the initial boiling point of the oil slurry as long as the amount of light components and heavy components after separation is not significantly different.

[0068] In the above method, the light component obtained in step 1 generally does not contain solid particles.

[0069] In step 2 of the above method, by selectively hydrogenating the light components according to their sulfur content, the sulfur content can be further reduced, and the composition of aromatics can be avoided while denitrogenating, thereby improving the utilization value of the light components.

[0070] In the above method, step 2 typically involves hydrogenating light components with a sulfur content greater than 3000 ppm. In specific implementations, for light components with a sulfur content of 3000 ppm or less, hydrogenation may or may not be performed; generally, hydrogenation is avoided to prevent additional operating costs.

[0071] In the above method, in step 2, the temperature of the hydrogenation treatment can be 300-330℃, and the pressure of the hydrogenation treatment can be 2-4 MPa. In some specific embodiments, the hydrogenation treatment of the light component in step 2 can be a one-step hydrogenation treatment or a step-by-step hydrogenation treatment. When a step-by-step hydrogenation treatment is used, the conditions for each step of the hydrogenation treatment can be the same or different, as long as the treatment conditions of 300-330℃ and 2-4 MPa are met.

[0072] In the above method, in step 2, the active component of the catalyst used for the hydrogenation treatment can be selected from Group VIB and / or Group VIII. That is, the active component can include one or more of the following elements: chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). In some specific embodiments, the active component of the catalyst used in step 2 can include one or more of the following elements: Mo, Co, Ni, and W.

[0073] In the hydrogenation catalyst used in step 2 above, the active component accounts for more than or equal to 1.0% of the mass of the catalyst, for example, 4%-15%. The support in the hydrogenation catalyst may include alumina.

[0074] In step 3 of the above method, mixing the heavy components with an organic solvent allows for good dissolution and dispersion of polycyclic aromatic hydrocarbons and sulfur- and nitrogen-containing heteroatom compounds in the solvent, breaking down aggregates formed by hydrogen bonds and other forces in polar compounds to form individual molecules. Therefore, in the organic solvent environment of this invention, the catalyst powder encapsulated or adsorbed by polar molecule aggregates will be released due to dissolution and depolymerization. The process of polarly mixing the heavy components with the organic solvent is a "physical depolymerization" process, which can release the solid particles "encapsulated" in the asphaltene. Subsequent filtration removes the solid particles, and the solvent removing the permeate side components yields the filtered oil slurry heavy components. The above process can effectively remove solid particles from the oil slurry while improving the overall utilization rate of the oil slurry.

[0075] In the above method, in step 3, the mass ratio of the organic solvent to the heavy component can be controlled to be 0.5-3:1.

[0076] In the above method, in step 3, the mixing temperature is 20-130℃, for example, it can be 50-130℃.

[0077] In the above method, in step 3, the mixing device can be a static device or a dynamic device, such as a static mixer, a mixing vessel, etc.

[0078] In the above method, step 4, the process of filtering and settling the mixed heavy components to obtain the permeate-side component and the concentrated-side component includes:

[0079] The mixed heavy components are filtered to obtain a permeation side component and a concentration side component. The concentration side component is subjected to sedimentation and solidification to separate solid particles. The sedimented and solidified concentration side component is mixed with the heavy components and organic solvents described in step 3.

[0080] Alternatively, the mixed heavy components are subjected to sedimentation and desolidification to separate solid particles. The sedimented mixed heavy components are then filtered to obtain permeation-side and concentration-side components. The concentration-side components are then mixed with the heavy components and organic solvents described in step 3.

[0081] In the above method, in step 4, the settling time for sedimentation and deconsolidation is 10-60 minutes. The particle size of the solid particles removed during the sedimentation and deconsolidation process is generally above 20 μm.

[0082] In the above method, step 4, the filtration method may include dead-end filtration and / or cross-flow membrane filtration. In some specific embodiments, the membrane material of the cross-flow membrane filter may include one or more of alumina (such as inorganic ceramics), metal (the membrane material is sintered from metal particles), and silicon carbide.

[0083] In the above method, in step 4, the components with a particle size greater than or equal to the pore size of the material used for filtration are retained on the concentration side and form concentration side components; the components with a particle size smaller than the pore size of the material used for filtration can permeate through the membrane material and form permeation side components.

[0084] In the above method, step 4, the filtration can be performed using either single-stage or two-stage filtration. The single-stage filtration uses a material with a pore size ≤ 0.5 μm. The two-stage filtration includes a first-stage filtration and a second-stage filtration; the first-stage filtration uses a material with a pore size ≤ 0.5 μm, and the second-stage filtration uses a material with a pore size ≤ 0.1 μm.

[0085] In the above method, in step 4, the mass concentration of solids in the heavy components of the filtered oil slurry after primary filtration and solvent removal is ≤50ppm; the concentration of solids in the heavy components of the filtered oil slurry after two-stage filtration and solvent removal is ≤20ppm.

[0086] In step 4 of the above method, by mixing the concentrated side components after sedimentation and desolidification with the heavy components and organic solvents, and then filtering them again to transfer them to the permeate side, solid particles can be transferred in an economical and energy-saving manner, thereby improving the utilization rate of the oil slurry.

[0087] In the above method, step 4, the solvent removal process on the permeate side, can be achieved through flash evaporation. After flash evaporation, the solvent and the filtered oil slurry heavy components are obtained separately. Flash evaporation relies on the boiling point difference between the heavy components and the solvent, releasing the material from a higher pressure to a lower pressure state, causing the lower-boiling-point substances to separate due to evaporation. The flash evaporation conditions depend on the boiling point of the solvent used. In some specific embodiments, the flash evaporation temperature can be 10°C lower than the solvent's boiling point, the pressure can be 10-50 kPa, and the flash evaporation environment is under negative pressure; for example, when the solvent is DMF, the flash evaporation temperature can be 130°C, and the pressure can be 10 kPa.

[0088] In the above method, step 4 may further include mixing the solvent removed from the permeation side with the heavy component and the organic solvent to form a mixed heavy component, thereby realizing the reuse of the solvent.

[0089] In step 4 of the above method, by performing deep hydrogenation treatment on the heavy components of the filtered oil slurry, sulfur and nitrogen can be removed and moderate aromatic saturation treatment can be achieved, thereby effectively reducing the sulfur and nitrogen content in the oil slurry. Furthermore, the heavy aromatics undergo moderate lightening, generating a structure that is conducive to the thermal polycondensation process and improving its value for further utilization.

[0090] In the above method, step 4, the hydrotreating of the heavy components of the filtered slurry, can be a one-step hydrotreating process or a step-by-step hydrotreating process, such as a two-step hydrotreating process. In a specific implementation, the choice between one-step or step-by-step hydrotreating can be made based on the asphaltene content and sulfur content. One-step hydrotreating has slightly lower efficiency but better economics; step-by-step hydrotreating has better efficiency but lower economics.

[0091] In some specific implementations, in step 4, the temperature of the one-step hydrogenation process can be controlled at 340-380°C, and the pressure can be controlled at 4-8 MPa.

[0092] In some specific implementations, step 4, the two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process. The temperature of the first-step hydrogenation process can be controlled at 300-330℃, and the pressure of the first-step hydrogenation process can be controlled at 2-4 MPa; the temperature of the second-step hydrogenation process can be controlled at 320-350℃, and the pressure of the second-step hydrogenation process can be controlled at 3-5 MPa.

[0093] In the above method, in step 4, the active component of the catalyst used in the hydrotreating of the heavy components of the filtered slurry can be selected from Group VIB and / or Group VIII; that is, the active component of the catalyst used in the first hydrotreating step and the second hydrotreating step is independently selected from Group VIB and / or Group VIII. Specifically, the active component of the catalyst used in the first hydrotreating step and / or the second hydrotreating step independently includes one or more of chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). In some specific embodiments, the active component of the catalyst used in the hydrotreating of the heavy components of the filtered slurry may include one or more of Mo, Co, Ni, and W.

[0094] In the above-mentioned hydrogenation catalyst, the active component accounts for more than or equal to 1.0% of the mass of the catalyst, for example, 4%-15%. The catalyst includes an active component and a support, and the support of the catalyst may include alumina.

[0095] The above method may further include step 5: mixing the light component (selectively hydrogenated) obtained in step 2 with the heavy component (hydrogenated in step 4) to obtain a refined oil slurry. This refined oil slurry can be used as a raw material for mesophase pitch or needle coke.

[0096] The pretreatment method provided by the present invention can improve the desolidification efficiency of oil slurry while reducing the desolidification depth, reducing energy consumption and cost, avoiding the generation of a large number of by-products, and improving the overall utilization rate of oil slurry; and while effectively reducing the sulfur and nitrogen content of heavy oil slurry with high sulfur and nitrogen content, it can increase the effective aromatic content and improve the utilization value of oil slurry.

[0097] According to a specific embodiment of the present invention, the above-mentioned selective deconsolidation and impurity removal pretreatment process for oil slurry specifically includes:

[0098] Step 1: Distill the oil slurry and separate the fraction into light and heavy components according to the fractionation temperature; the fractionation temperature is one of 400-480℃.

[0099] Step 2: Hydrogenate light components with a sulfur content greater than 3000 ppm. The hydrogenation conditions are: temperature 300-330℃, pressure 2-4 MPa. Hydrogenation is not required for light components with a sulfur content less than or equal to 3000 ppm.

[0100] Step 3: Mix the heavy component (enriched solid particles) obtained in Step 1 with an organic solvent at a mass ratio of 1:0.5-2 at 20-130℃ to obtain a mixed component; the above mixing process can promote the release of solid particles "encased" in the asphalt by the heavy component.

[0101] Step 4:

[0102] (1) Filter the mixed components to obtain a concentrated side component (enriched with solid particles) and a permeation side component (removed with solid particles); the concentrated side component is subjected to sedimentation and solidification and the solid particles are separated; the concentrated side component after sedimentation and solidification is reused in step 3 and mixed with heavy components and organic solvents to form a mixed heavy component; the concentrated side component after sedimentation and solidification enters the permeation side in part or all after being filtered again.

[0103] Alternatively, the mixed components can be sedimented and desolidified to separate solid particles. The sedimented and desolidified components can be filtered to obtain concentrated side components and permeation side components. The concentrated side components can be recycled to step 3 and mixed with heavy components and organic solvents to form mixed heavy components.

[0104] In the above process, filtration can be carried out using a single-stage filtration method or a two-stage filtration method;

[0105] (2) The permeate-side components are desolventized by flash evaporation. The desolventized solvent can be optionally reused in step 3 and mixed with the heavy components and organic solvent to form a mixed component. The mass concentration of solids in the permeate-side components (the heavy components of the filtered slurry) after primary filtration and solvent removal is ≤50ppm, and the mass concentration of solids in the permeate-side components after secondary filtration and solvent removal is ≤20ppm.

[0106] The permeate-side components after solvent removal are subjected to one-step or two-step hydrogenation treatment to obtain hydrogenated oil slurry heavy components.

[0107] The conditions for one-step hydrogenation are: temperature 340-380℃ and pressure 4-8MPa;

[0108] The two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process. The conditions for the first-step hydrogenation process are a temperature of 300-330℃ and a pressure of 2-4 MPa; the conditions for the second-step hydrogenation process are a temperature of 320-350℃ and a pressure of 3-5 MPa.

[0109] Step 5: Mix the light component obtained in Step 2 with the heavy component of the hydrogenated slurry obtained in Step 4 to form a refined slurry, thus completing the selective deconsolidation and impurity removal pretreatment of the slurry.

[0110] In the above steps, there is no special requirement for the order of steps 2 and 3. Step 2 can be performed first and then step 3, or step 3 can be performed first and then step 2, or steps 2 and 3 can be performed simultaneously.

[0111] The present invention will be described in detail below through embodiments.

[0112] In the following embodiments,

[0113] The particle size of the catalyst particles remaining in the extraction phase 1 was obtained by a particle size analyzer. The testing principle was laser diffraction, and the principle is described in ISO 13320-1.

[0114] The yield of aromatic hydrocarbon-rich slurry in the product is the portion remaining after slurry pretreatment to remove residual oil and solid particles, which is calculated by weighing.

[0115] The composition of the solid residue oil was analyzed by gas chromatography-mass spectrometry in accordance with NB / SH / T0509-2010 "Determination of Four Components of Petroleum Asphalt".

[0116] Solid content is calculated by weighing a certain amount of sample and determining the proportion of solid particles retained on the filter paper (filter paper pore size ≤ 0.7 μm) to the sample mass.

[0117] The viscosity of the extraction phase 3 was measured according to GB / T11137;

[0118] Furfural and DMF reagents are of analytical grade with a purity of not less than 95%;

[0119] In this embodiment of the invention, the slurry feedstock is derived from the heavy components of the catalytic cracking products containing solid catalyst powder, which are thrown off the bottom of the distillation tower of the catalytic cracking unit. The saturated components in the slurry feedstock are mainly alkanes. Detailed parameters are shown in Table 1.

[0120] Example 1

[0121] The process flow diagram of this embodiment is shown in Figure 1: Furfural, an organic solvent, is used as the extractant and is separated from slurry feedstock 1 at a ratio of 0.5:1 and fed into the extraction tower of the extraction unit. Furfural enters from the top inlet of the extraction tower; slurry feedstock 1 enters from the bottom of the extraction tower, and they are in countercurrent contact within the tower. The extraction tower temperature is set to 40°C, and the extraction time is set to 10 min. After extraction, an upper raffinate phase 1 and a lower extractable phase 1 are obtained. Raffinate phase 1 overflows from the top of the tower and settles in a settling tank (with a narrowed bottom) to separate into layers. The upper raffinate oil is returned to the catalytic cracking unit as feedstock, and the lower organic solvent, rich in solid components at the bottom, is returned to the extraction tower for reuse. The settling tank temperature is set to 20°C, and the settling time is 2 h.

[0122] Extraction phase 1 is collected from the bottom of the extraction column. Due to the low proportion of furfural added, a process of first removing solids and then removing organic solvents is adopted. Cross-flow membrane filtration is performed using a membrane tube with a pore size of 0.1 μm. After filtration, a deeply desolventized filtrate is obtained, which is then subjected to flash evaporation and stripping distillation to remove organic solvents, resulting in a deeply desolventized aromatic-rich slurry. The removed organic solvents are returned to the extraction column for reuse. The concentrate containing solids after membrane filtration is returned to the extraction unit for processing. The basic properties of slurry feedstock 1 are shown in Table 1 below. The yield of the final product, the aromatic-rich slurry, is 92.5%, and the solid content is 18.7 ppm.

[0123] Example 2

[0124] The process flow diagram of this embodiment is shown in Figure 2: Furfural, an organic solvent, is used as the extractant and fed separately with oil slurry feedstock 2 at a ratio of 1.5:1 into the extraction tower. Furfural enters from the top inlet of the extraction tower, while oil slurry feedstock 2 enters from the bottom, resulting in countercurrent contact within the tower. The extraction tower temperature is set to 80°C, and the extraction time is set to 30 minutes. After extraction, an upper raffinate phase 1 and a lower extractable phase 1 are obtained. The raffinate phase overflows from the top of the tower and settles in a settling tank (with a narrowed bottom) to separate into layers. The upper raffinate oil is returned to the catalytic cracking unit as feedstock, and the lower organic solvent, rich in solid components at the bottom, is returned to the extraction tower for reuse. The settling tank temperature is set to 30°C, and the settling time is 4 hours.

[0125] Extractive phase 1 was collected from the bottom of the extraction column. Due to the high proportion of furfural solvent added, a process of first removing the organic solvent and then removing the solids was adopted. Flash evaporation was first performed to remove most of the organic solvent, yielding extractive phase 3 (viscosity 30 mm). 2 / s), the removed organic solvent is returned to the extraction tower for reuse.

[0126] Extraction phase 3 enters the desolidification unit, where it undergoes cross-flow membrane filtration using a 0.5 μm pore size membrane tube. After filtration, a deeply desolidified filtrate is obtained. This filtrate is then stripped by distillation to remove residual solvent, yielding the extracted oil, i.e., the aromatic-rich oil slurry. The solids-containing concentrate after membrane filtration is returned to the extraction unit. The basic properties of oil slurry feedstock 2 are shown in Table 1 below. The final product shows an aromatic-rich oil slurry yield of 87.2% and a solids content of 30.3 ppm.

[0127] Example 3

[0128] The process flow diagram of this embodiment is shown in Figure 2. Furfural, an organic solvent, is used as the extractant and fed separately to the extraction tower with oil slurry feedstock 3 at a ratio of 3:1. Furfural enters from the top inlet of the extraction tower, while oil slurry feedstock 3 enters from the bottom, resulting in countercurrent contact within the tower. The extraction tower temperature is set at 120°C, and the extraction time is set at 60 min. After extraction, an upper raffinate phase 1 and a lower extractable phase 1 are obtained. The raffinate phase overflows from the top of the tower and settles in a settling tank (with a narrowed bottom) to separate into layers. The upper raffinate oil is returned to the catalytic cracking unit as feedstock, and the lower organic solvent, rich in solid components at the bottom, is returned to the extraction tower for reuse. The settling tank temperature is set at 60°C, and the settling time is 8 h.

[0129] Extractive phase 1 was collected from the bottom of the extraction column. Due to the high proportion of furfural solvent added, a process of first removing the organic solvent and then solidifying was adopted. Flash evaporation was first performed to remove most of the organic solvent, yielding extractive phase 3 (viscosity 20 mm). 2 / s), the removed organic solvent is returned to the extraction tower for reuse.

[0130] Extraction phase 3 enters the deconsolidation unit, where it undergoes cross-flow membrane filtration using a 0.1 μm pore size membrane tube. After filtration, a deeply deconsolidated filtrate is obtained. This filtrate is then stripped by distillation to remove residual solvent, yielding the extracted oil, i.e., the aromatic-rich slurry. The basic properties of slurry feedstock 3 are shown in Table 1 below. The final product, containing aromatic-rich slurry, has a yield of 95.2% and a solid content of 15 ppm.

[0131] Example 4

[0132] The method was followed in Example 2, except that the solidification of the extraction phase 3 was performed using a dead-end filtration process with a 0.5 μm sintered metal mesh; all other conditions remained unchanged. The final product had an aromatic-rich oil slurry yield of 87.8% and a solid content of 37.2 ppm.

[0133] Example 5

[0134] The method was followed in Example 3, except that the solidification of the extraction phase 3 was performed using a static sedimentation process, while other conditions remained unchanged. The yield of the aromatic-rich oil slurry in the final product was 89.5%, and the solid content was 49.3 ppm.

[0135] Example 6

[0136] The process flow diagram of this embodiment is shown in Figure 1: Organic solvent DMF is used as the extractant and fed separately to the extraction tower with oil slurry feedstock 1 at a ratio of 0.5:1. DMF enters from the bottom inlet of the extraction tower; oil slurry feedstock 1 enters from the top, and they are in countercurrent contact within the tower. The extraction tower temperature is set to 40℃, and the extraction time is set to 10 min. After extraction, an upper raffinate phase 1 and a lower extractable phase 1 are obtained. The raffinate phase overflows from the top of the tower and settles in a settling tank (with a narrowed bottom) to separate into layers. The upper raffinate oil is returned to the catalytic cracking unit as feedstock, and the lower organic solvent, rich in solid components at the bottom, is returned to the extraction tower for reuse. The settling tank temperature is set to 20℃, and the settling time is 2 h.

[0137] Extraction phase 1 was collected from the bottom of the extraction column. Due to the low proportion of DMF solvent added, a process of first removing the solids and then removing the organic solvent was adopted. Cross-flow membrane filtration was performed using a membrane tube with a pore size of 0.1 μm. After filtration, a deeply desolventized filtrate was obtained, which was then subjected to flash evaporation and stripping distillation to remove the organic solvent, resulting in a deeply desolventized aromatic-rich slurry. The removed organic solvent was returned to the extraction column for reuse. The concentrate containing solids after membrane filtration was returned to the extraction unit for further processing. The final product had an aromatic-rich slurry yield of 95.3% and a solids content of 11.2 ppm.

[0138] Example 7

[0139] Following the method of Example 2, the difference is that the ratio of furfural to oil slurry feedstock 2 is 4:1, and a process of first removing the organic solvent and then desoldering is adopted. The yield of the aromatic-rich oil slurry in the final product is 88.5%, and the solid content is 23 ppm. Analysis of the results shows that excessive addition of organic solvent improves the selectivity of extraction and separation, reduces the proportion of saturated fraction in the raffinate phase 1, and worsens the adhesion effect on the catalyst powder in the oil slurry. Because the extraction phase 1 contains a large amount of organic solvent, its viscosity is too low, causing some catalyst powder to enter the extraction phase 1. However, the desoldering effect can be achieved after subsequent desoldering. Due to the large amount of organic solvent used in the extraction, energy consumption is correspondingly increased, making this not a preferred solution.

[0140] Comparative Example 1

[0141] The method was followed in Example 2, except that the ratio of furfural to raw material No. 2 was 0.3:1. At this ratio, a process of first removing the solids and then removing the organic solvents was employed. The final product had an aromatic-rich oil slurry yield of 82.3% and a solid content of 108.9 ppm, which did not meet the required solid content.

[0142] Table 1 Basic Parameters of Oil Slurry Raw Materials

[0143] In the following embodiments, both oil slurry feedstock No. 4 and oil slurry feedstock No. 5 are catalytic cracking oil slurries.

[0144] Oil slurry feedstock No. 4 (solid content 3120 ppm) contains 20.17 wt% saturated matter, 61.27 wt% aromatic matter, 15.42 wt% resin, and 3.14 wt% asphaltenes; the solid content is 3120 ppm.

[0145] In oil slurry feedstock No. 5 (solid content of 2150 ppm), the content of saturated matter is 63.73 wt%, the content of aromatic matter is 18.66 wt%, the content of resin is 16.27 wt%, and the content of asphaltenes is 1.34 wt%.

[0146] Example 8

[0147] According to the process flow shown in Figure 3, the oil slurry raw material No. 4 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 70% by adjusting the feed pressure, and the membrane pore size is 0.1μm.

[0148] The organic solvent furfural and concentrated oil slurry (density 1.0182 g / cm³) were mixed. 3 The slurry was injected into the turbine extraction tower at a ratio of 0.5:1. Furfural entered through the top inlet of the extraction tower, while the concentrated slurry entered through the bottom, where it was in countercurrent contact. The extraction tower temperature was set at 40℃, and the extraction time was set at 10 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 40℃ for 0.5 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. Therefore, the raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where it was flash-evaporated to remove the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This extractable oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desolidified clarified slurry.

[0149] The final product, clarified oil slurry, has a solid content of 37.6 ppm and a total yield of 90%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.43 kg.

[0150] Example 9

[0151] According to the process flow shown in Figure 3, the oil slurry raw material No. 4 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 80% by adjusting the feed pressure, and the membrane pore size is 0.15μm.

[0152] The extractant DMF and concentrated oil slurry (density 1.0182 g / cm³) were mixed. 3The DMF was injected into the turbine extraction tower at a 1:1 ratio, with the DMF entering through the lower inlet and the concentrated slurry entering through the upper inlet, where they were in countercurrent contact. The extraction tower temperature was set at 50°C and the extraction time at 30 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 50°C for 1 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. This raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where flash evaporation removed the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This extractable oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desoldered clarified slurry.

[0153] The final product, clarified oil slurry, has a solid content of 42.3 ppm and a total yield of 95%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.25 kg.

[0154] Example 10

[0155] According to the process flow shown in Figure 3, the oil slurry raw material No. 4 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 90% by adjusting the feed pressure, and the membrane pore size is 0.2μm.

[0156] The extractant DMF and concentrated oil slurry (density 1.0182 g / cm³) were mixed. 3 The DMF was injected into the turbine extraction tower at a ratio of 2:1, with the DMF entering through the lower inlet and the concentrated slurry entering through the upper inlet, where they were in countercurrent contact. The extraction tower temperature was set at 60°C and the extraction time at 30 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 60°C for 0.5 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. This raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where flash evaporation removed the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This extractable oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desoldered clarified slurry.

[0157] The final product, clarified oil slurry, has a solid content of 58.9 ppm and a total yield of 98%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.1 kg.

[0158] Example 11

[0159] According to the process flow shown in Figure 3, the oil slurry raw material No. 5 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 70% by adjusting the feed pressure, and the membrane pore size is 0.1μm.

[0160] The extractant furfural and concentrated oil slurry (density 0.956 g / cm³) were mixed. 3 The concentrate was injected into the turbine extraction tower at a mass ratio of 0.5:1. Furfural entered through the top inlet of the extraction tower, while the concentrated slurry entered through the bottom, where it was in countercurrent contact within the tower. The extraction tower temperature was set at 40℃, and the extraction time was set at 10 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 40℃ for 1 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. Therefore, the raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where it was flash-evaporated to remove the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This extractable oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desolidified clarified slurry.

[0161] The final product, clarified oil slurry, has a solid content of 26.8 ppm and a total yield of 90%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.43 kg.

[0162] Example 12

[0163] According to the process flow shown in Figure 3, the oil slurry raw material No. 5 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 80% by adjusting the feed pressure, and the membrane pore size is 0.15μm.

[0164] The extractant DMF and concentrated oil slurry (density 0.956 g / cm³) were mixed. 3 The DMF was injected into the turbine extraction tower at a 1:1 ratio, with the DMF entering through the lower inlet and the concentrated slurry entering through the upper inlet, where they were in countercurrent contact. The extraction tower temperature was set at 50°C and the extraction time at 30 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 50°C for 0.5 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. This raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where flash evaporation removed the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desoldered clarified slurry.

[0165] The final product, clarified oil slurry, has a solid content of 37.8 ppm and a total yield of 95%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.25 kg.

[0166] Example 13

[0167] According to the process flow shown in Figure 3, the oil slurry raw material No. 5 is fed into the cross-flow membrane filter to obtain clarified oil slurry and concentrated oil slurry. The single-pass throughput of the clarified oil slurry is maintained at 90% by adjusting the feed pressure, and the membrane pore size is 0.2μm.

[0168] The extractant DMF and concentrated oil slurry (density 0.956 g / cm³) were mixed. 3 The DMF was injected into the turbine extraction tower at a ratio of 2:1, with the DMF entering through the lower inlet and the concentrated slurry entering through the upper inlet, where they were in countercurrent contact. The extraction tower temperature was set at 60℃ and the extraction time at 30 min. The raffinate and extractable phases were obtained. The raffinate entered a bottom-constricted settling tank at 60℃ for 1.5 h. After settling, it separated into an upper layer of raffinate containing solids and a lower layer containing a large amount of solid particles. Analysis of the composition of the raffinate containing solids revealed that the saturated fraction was mainly alkanes. This raffinate containing solids can be returned to the catalytic cracking unit for reprocessing after stripping distillation or vacuum distillation, while the lower layer is discharged. The extractable phase entered the recovery unit, where flash evaporation removed the extractant, resulting in an aromatic-enriched extractable oil (containing a small amount of solid particles). This extractable oil was then returned to a cross-flow membrane filtration unit for secondary filtration, yielding an aromatic-enriched and deeply desoldered clarified slurry.

[0169] The final product, clarified oil slurry, has a solid content of 51.2 ppm and a total yield of 98%. The membrane filtration capacity corresponding to 1 kg of clarified oil slurry product is 1.1 kg.

[0170] The following embodiment provides a selective deconsolidation and impurity removal pretreatment system for oil slurry, as shown in Figures 4 and 5. The system includes: a distillation unit 1, a mixing unit 2, a filtration unit 3, a sedimentation unit 4, a flash evaporation unit 5, a light component hydrogenation unit 6, and a heavy component hydrogenation unit 7.

[0171] The pretreatment methods in the following embodiments can be performed in the above-mentioned selective deconsolidation and impurity removal pretreatment system for oil slurry.

[0172] Example 14

[0173] This embodiment provides a method for selective deconsolidation and impurity removal pretreatment of oil slurry, as shown in Figure 4. The method includes:

[0174] (1) The oil slurry raw material No. 6 was distilled and cut at 440℃ to obtain 60% light component and 40% heavy component by mass.

[0175] (2) The sulfur content in the light component is 8800 ppm. The light component is hydrogenated using a catalyst at 330°C and 2 MPa.

[0176] (3) DMF is used as the physical depolymerization solvent for the heavy components. The mass ratio of physical depolymerization solvent to heavy components is 1.5:1. After the oil slurry and DMF are heated to 90°C, they are mixed in a static mixer to obtain a mixture.

[0177] The mixture exiting the static mixer enters a cross-flow membrane filtration unit, which uses a metal membrane tube with a filtration precision (i.e., material pore size) of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component undergoes sedimentation and desolidification before returning to the static mixer to mix with the heavy components and DMF, and then undergoes a second filtration.

[0178] (4) The permeate slurry is preheated to 130°C and enters the flash evaporation unit. Flash evaporation is carried out at a pressure of 10 kPa. After the solvent is recovered, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to one-step hydrogenation treatment at a temperature of 380°C and a pressure of 4 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and DMF.

[0179] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0180] The active component of the hydrogenation catalyst used in step (2) contains Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 12% of the mass of the catalyst, and the remainder is an alumina support.

[0181] The active component of the hydrogenation catalyst used in step (4) contains Mo and Ni elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 10% of the mass of the catalyst, and the remainder is an alumina support.

[0182] The oil slurry feedstock No. 6 used in this embodiment is a high-sulfur heavy oil slurry. The specific physical properties of oil slurry feedstock No. 6 and the refined oil slurry are shown in Table 2. Specifically, when the oil slurry used in this embodiment is cut at an AET temperature (atmospheric pressure equivalent temperature) of 440℃, the cumulative yield of the light fraction is 60%, and the cumulative yield of the heavy fraction is 40%. A solvent with a mass of 1.5 times the heavy fraction is used in the physical depolymerization and filtration stages. The permeate recovery rate is 95%, with a solid particulate content of 30 ppm and a solidification rate of 98%. The refined oil slurry contains 5.5% more tri- and tetra-cyclic aromatic hydrocarbons (substances with three or four parallel aromatic rings, such as phenanthrene and pyrene compounds), achieving an overall desulfurization rate of 72% and a denitrification rate of 22%. The treatment process produces no byproducts other than solid particles, and the oil slurry utilization rate is 100%.

[0183] Example 15

[0184] This embodiment provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry treated in this embodiment is the same as that in Embodiment 14. Steps (1), (2), and (5) of the method provided in this embodiment are the same as steps (1), (2), and (5) of Embodiment 14. Steps (3) and (4) of this embodiment are as follows:

[0185] Step (3): DMF is used as the physical depolymerization solvent for the heavy components. The mass ratio of physical depolymerization solvent to heavy components is 1.5:1. After the oil slurry and DMF are heated to 90°C, they are mixed in a static mixer to obtain a mixture.

[0186] The mixture exiting the static mixer enters the filtration unit, which employs a two-stage cross-flow membrane filtration system. The first stage uses a metal-ceramic membrane with a filtration precision of 0.5 μm, while the second stage uses an inorganic ceramic membrane with a filtration precision of 0.1 μm. The permeate side of the first stage undergoes secondary filtration, yielding permeate-side components from the second stage and concentrated-side components from both stages. The concentrated-side components undergo sedimentation and deconsolidation before returning to the mixing unit for further filtration.

[0187] Step (4): The permeate slurry is preheated to 130°C and enters the flash evaporation unit. Flash evaporation is carried out at a pressure of 10 kPa. After solvent recovery, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to two-step hydrogenation treatment. The temperature of the first step hydrogenation treatment is 320°C and the pressure is 3 MPa. The temperature of the second step hydrogenation treatment is 360°C and the pressure is 6 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and DMF.

[0188] The active components of the first-step hydrogenation catalyst used in step (4) contain Mo and W elements. Based on the total mass of the catalyst, the active components (based on element content) account for 6% of the mass of the catalyst, and the remainder is alumina support. Based on the total mass of the catalyst, the active components of the second-step hydrogenation catalyst are Ni and Mo. The active components (based on element content) account for 12% of the mass of the catalyst, and the remainder is alumina support.

[0189] In this embodiment, the slurry feedstock used is Slurry Feedstock No. 6. The specific physical properties of Slurry Feedstock No. 6 and the refined slurry are shown in Table 2. Due to the two-stage filtration, the second-stage filtration membrane has high separation accuracy, with a permeate recovery rate of 80%, a solid particulate matter content of 10 ppm, and a solidification rate of 99%. A two-step hydrogenation process increases the tri- and tetra-cyclic aromatic hydrocarbon content in the refined slurry by 9.2%, achieving an overall desulfurization rate of 80% and a denitrification rate of 30%. The treatment process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0190] Example 16

[0191] This embodiment provides a method for selective deconsolidation and impurity removal pretreatment of oil slurry. The oil slurry used is oil slurry raw material No. 7, as shown in Figure 4. The method includes the following steps:

[0192] (1) The oil slurry was distilled and cut at 420°C to obtain 30% light components and 70% heavy components.

[0193] (2) The sulfur content in the light component is 9500 ppm. The light component is hydrogenated using a catalyst at 300℃ and 4MPa.

[0194] (3) Furfural is used as the physical depolymerization solvent for the heavy components. The mass ratio of the depolymerization solvent to the heavy components is 1.0:1. After the oil slurry and furfural are heated to 100°C, they are mixed in a static mixer to obtain a mixture.

[0195] The mixture exiting the static mixer enters a cross-flow membrane filtration unit, which uses an inorganic ceramic membrane tube with a filtration precision of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-diameter solids and a concentrated-side component enriched with large-diameter solids are obtained. The concentrated-side component undergoes sedimentation and desolvation before being returned to the static mixer to mix with the heavy components and furfural, and then undergoes a second filtration.

[0196] (4) The permeate slurry enters the flash evaporation unit for flash evaporation. The flash evaporation temperature is 10°C lower than the solvent boiling point, and the pressure is 10-50 kPa. The flash evaporation unit is under negative pressure. After recovering the solvent, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2 MPa. The second hydrogenation treatment temperature is 340°C and the pressure is 8 MPa. The recovered solvent is returned to the static mixer to mix with the heavy components and furfural.

[0197] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0198] The active component of the hydrogenation catalyst used in step (2) contains Co, Mo and W elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 8% of the mass of the catalyst, and the remainder is an alumina support.

[0199] The active component of the hydrogenation catalyst used in step (4) contains Ni, Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 14% of the mass of the catalyst, and the remainder is an alumina support.

[0200] The specific physical properties of the No. 7 slurry feedstock and the refined slurry in this embodiment are shown in Table 2. In this embodiment, when the slurry is cut at an AET temperature of 420℃, the cumulative yield of the light fraction is 30%, and the cumulative yield of the heavy fraction is 70%. A solvent with a mass equal to 1.0 times the mass of the heavy fraction is used in the physical depolymerization and filtration stages. The permeate recovery rate is 85%, with a solid particulate content of 50 ppm and a solidification rate of 95%. The refined slurry shows a 10.0% increase in tri- and tetra-cyclic aromatic hydrocarbons, an overall desulfurization rate of 80%, and a denitrification rate of 40%. The process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0201] Example 17

[0202] This embodiment provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry used is oil slurry raw material No. 8. As shown in Figure 5, the steps (1), (2), (4), and (5) of the pretreatment method in this embodiment are basically the same as the steps (1), (2), (4), and (5) of Embodiment 4. The process of step (3) in this embodiment is as follows:

[0203] Step (3): NMP was used as the physical depolymerization solvent for the heavy components, with a mass ratio of solvent to heavy components of 2:1. After the oil slurry and NMP were heated to 50°C, they were mechanically stirred in a mixing vessel for 30 minutes. Then, the mixture was transferred to a settling unit for sedimentation and desolidification. The supernatant obtained from sedimentation and desolidification was transferred to a cross-flow membrane filtration unit using an inorganic ceramic membrane tube with a filtration accuracy of 0.1 μm. After filtration, permeate-side components and concentrate-side components were obtained. The concentrate-side components were returned to the mixing vessel to be mixed with the heavy components and NMP and then filtered again.

[0204] The specific physical properties of the No. 8 slurry feedstock and the refined slurry in this embodiment are shown in Table 2. In this embodiment, when the slurry is cut at an AET temperature of 400℃, the cumulative yield of the light fraction is 60%, and the cumulative yield of the heavy fraction is 40%. The solvent used in the physical depolymerization and filtration stages is twice the mass of the heavy fraction. The permeate recovery rate is 95%, with a solid particulate content of 10 ppm and a solidification rate exceeding 98%. The refined slurry shows a 2% increase in tri- and tetra-cyclic aromatic hydrocarbons, an overall desulfurization rate of 65%, and a denitrification rate of 6%. The process produces no byproducts other than solid particles, and the slurry utilization rate is 100%.

[0205] Example 18

[0206] This embodiment provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry used is oil slurry raw material No. 9, which is a high-sulfur heavy oil slurry, as shown in Figure 4. The pretreatment method includes the following steps:

[0207] (1) The oil slurry was distilled and cut at 480°C to obtain 80% light components and 20% heavy components.

[0208] (2) The sulfur content in the light component is 10200 ppm. A two-step hydrogenation treatment is carried out using a light component hydrogenation catalyst. The first step hydrogenation treatment temperature is 300℃ and 4MPa, and the second step hydrogenation treatment temperature is 350℃ and 3MPa.

[0209] (3) DMF was used as the physical depolymerization solvent for the heavy components. The mass ratio of the depolymerization solvent to the heavy components was 2.0:1. After the oil slurry and DMF were heated to 120°C, they were stirred mechanically in a mixing vessel for 30 minutes to obtain a mixture.

[0210] The mixture enters a cross-flow membrane filtration unit, using an inorganic ceramic membrane tube with a filtration precision of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component undergoes sedimentation and desolvation before being returned to the mixing vessel to be mixed with the heavy components and DMF for further filtration.

[0211] (4) The permeate slurry enters the flash evaporation unit for flash evaporation. The flash evaporation temperature is 10°C lower than the solvent boiling point, and the pressure is 10-50 kPa. The flash evaporation unit is under negative pressure. After the solvent is recovered, the filtered slurry heavy components are obtained. The filtered slurry heavy components are subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 4 MPa. The second hydrogenation treatment temperature is 350°C and the pressure is 5 MPa.

[0212] (5) The light component and the heavy component after hydrogenation are mixed to obtain refined oil slurry, which can be used as raw material for needle coke.

[0213] The active component of the hydrogenation catalyst used in step (2) contains Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 9% of the mass of the catalyst, and the remainder is an alumina support.

[0214] The active component of the hydrogenation catalyst used in step (4) contains Ni, Mo and Co elements. Based on the total mass of the catalyst, the active component (based on element content) accounts for 15% of the mass of the catalyst, and the remainder is an alumina support.

[0215] The specific physical properties of the No. 9 slurry feedstock and the refined slurry in this embodiment are shown in Table 2. In this embodiment, when the slurry is cut at an AET temperature of 480℃, the cumulative yield of the light fraction is 80%, and the cumulative yield of the heavy fraction is 20%. A solvent with a mass equal to 2.0 times the mass of the heavy fraction is used in the physical depolymerization and filtration stages. The permeate recovery rate is 90%, with a solid particulate content of 50 ppm, achieving a solidification rate of 95%. The overall desulfurization rate of the slurry reaches 85%, and the denitrification rate reaches 35%. Due to the increased hydrogenation depth, the content of tri- and tetra-cyclic aromatic hydrocarbons in the refined slurry does not increase. Besides solid particles, there are no other byproducts in the processing, and the slurry utilization rate is 100%.

[0216] Comparative Example 2

[0217] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 16. The difference between the oil slurry pretreatment method provided in this comparative example and the method in Example 16 is that the oil slurry is not cut, and the entire fraction is filtered and hydrogenated.

[0218] Step (1): The oil slurry was not cut;

[0219] Step (2): The whole fraction is treated with DMF as the physical depolymerization solvent, with a depolymerization solvent to oil slurry mass ratio of 0.5:1. The whole fraction and DMF are mixed in a static mixer, and the mixture enters a cross-flow membrane filtration unit. An inorganic ceramic membrane tube is used, with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component and a concentrate-side component are obtained. The concentrate-side component is settled and desolidified, then returned to the static mixer to be mixed with the whole fraction and DMF for further filtration.

[0220] Step (3): After the solvent is recovered by the flash evaporation unit, the complete component of the slurry is obtained (flash evaporation conditions are the same as in Example 3). The complete component of the slurry is subjected to stepwise hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2MPa; the second hydrogenation treatment temperature is 340°C and the pressure is 8MPa. The catalyst used for hydrogenation treatment is the same as in Example 3. The recovered solvent is returned to the static mixer and mixed with the whole fraction and DMF.

[0221] The entire composition of the hydrotreated slurry is used as the refined slurry.

[0222] The physical properties of the slurry and refined slurry used in this comparative example are shown in Table 2. The slurry used in this comparative example was not cut; the entire fraction underwent physical depolymerization and filtration. Due to the consistent membrane filtration precision, the solidification rate was comparable, reaching 95%. However, the solvent consumption was high, and the filtration process and permeate flash evaporation solvent recovery process involved large volumes and high energy consumption. The entire fraction underwent hydrogenation, with a high degree of hydrogenation, resulting in a 5.3% loss of tri- and tetra-cyclic aromatic hydrocarbons in the refined slurry. The treatment process produced no byproducts other than solid particles, and the slurry utilization rate was 100%.

[0223] Comparative Example 3

[0224] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 16. The difference between the pretreatment method provided in this comparative example and the method in Example 16 lies in the order of cutting and filtering. The specific process is as follows:

[0225] Step (1): The oil slurry was not cut or subjected to physical depolymerization. Instead, all the oil slurry was directly introduced into a cross-flow membrane filtration unit for desolidification. An inorganic ceramic membrane tube was used, with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component and a concentrate-side component were obtained. In the concentrate-side component, the solid particles and the asphaltene in the oil slurry were in a "coupling" state and could not be settled and desolidified.

[0226] Step (2): After the solvent is recovered in the flash evaporation unit, the total components of the slurry are obtained (flash evaporation conditions are the same as in Example 3). The slurry is then cut at AET 420°C to obtain 30% light components and 70% heavy components. The light and heavy components are then hydrogenated separately under the same conditions as in Example 3. The hydrogenated light and heavy components are then mixed to obtain the refined slurry.

[0227] The specific physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 2. The oil slurry used in this comparative example was not cut and was not subjected to physical depolymerization. After solvent recovery on the permeation side, 85% of the oil slurry was obtained, and 15% of the concentrated side component was generated, which could not be further desolidified and utilized, resulting in an oil slurry utilization rate of only 85%.

[0228] Comparative Example 4

[0229] This comparative example provides a selective desolidification and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 16. The difference between the pretreatment method provided in this comparative example and Example 16 is that no cutting was performed before or after filtration, and no solvent was added during the filtration process. The specific process is as follows:

[0230] Step (1): The oil slurry was not cut or subjected to physical depolymerization. Instead, all the oil slurry was directly introduced into a cross-flow membrane filtration unit for desolidification. An inorganic ceramic membrane tube was used, with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component and a concentrate-side component were obtained. In the concentrate-side component, the solid particles and the asphaltene in the oil slurry were in a "coupling" state and could not be settled and desolidified.

[0231] Step (2): After the solvent is recovered by the flash evaporation unit, the slurry on the permeate side is obtained as the complete slurry component (flash evaporation conditions are the same as in Example 3). The component is not cut. The complete component is subjected to step-by-step hydrogenation treatment. The first hydrogenation treatment temperature is 330°C and the pressure is 2MPa; the second hydrogenation treatment temperature is 340°C and the pressure is 8MPa. The catalyst used for hydrogenation treatment is the same as in Example 3. The slurry after hydrogenation treatment is used as refined slurry.

[0232] The physical properties of the slurry and refined slurry used in this comparative example are shown in Table 2. The slurry used in this comparative example was not cut, and no polar solvent was used for physical depolymerization. After solvent recovery from the permeate side, the slurry comprised 85% of the total component, resulting in a 15% concentrate side component that could not be further desoldered or utilized, leading to a slurry utilization rate of only 85%. Due to hydrogenation of the entire fraction at a relatively high depth, the refined slurry suffered a 5.3% loss of tri- and tetra-cyclic aromatic hydrocarbons.

[0233] Comparative Example 5

[0234] This comparative example provides a selective deconsolidation and impurity removal pretreatment method for oil slurry. The oil slurry treated in this comparative example is the same as that in Example 16. The difference between the oil slurry pretreatment method provided in this comparative example and Example 16 is that no further deconsolidation is performed on the concentrated side components after filtration. The specific process is as follows:

[0235] Steps (1) and (2) are the same as steps (1) and (2) in Example 3;

[0236] Step (3): Furfural is used as the physical depolymerization solvent for the heavy components. The mass ratio of the depolymerization solvent to the heavy components is 1.0:1. After the oil slurry and furfural are heated to 100°C, they are mixed in a static mixer to obtain a mixture.

[0237] The mixture exiting the static mixer enters the cross-flow membrane filtration unit, which uses an inorganic ceramic membrane tube with a filtration accuracy of 0.5 μm. After filtration, a permeate-side component containing trace amounts of small-particle solids and a concentrated-side component enriched with large-particle solids are obtained. The concentrated-side component is not subjected to sedimentation and desolvation but is directly returned to the static mixer to be mixed with the heavy components and furfural for further filtration.

[0238] Steps (4) and (5) are the same as steps (4) and (5) in Example 3.

[0239] The specific physical properties of the oil slurry and refined oil slurry in this comparative example are shown in Table 2. Since the components on the concentrated side were not subjected to sedimentation and desolidification, the content of solid particles in the material processed by the filtration unit became higher and higher, and the permeation yield became lower and lower, resulting in the inability to continuously filter the oil slurry and low utilization of the oil slurry.

[0240] Table 2

[0241] In Table 2, the yields of light and heavy components represent the light and heavy weights of the feedstock slurry, and the sulfur content indicates whether the feedstock slurry is high in sulfur. In slurry utilization, the focus is mainly on the ideal components containing 3-4 ring aromatics, and the non-ideal components, primarily solid particles, sulfur, and nitrogen. This invention primarily focuses on the increase or decrease of ideal components during the removal of non-ideal components.

[0242] The above results demonstrate that the pretreatment method provided by this invention selectively and deeply desolidifies and removes impurities based on the composition characteristics of the oil slurry. This method can minimize the processing volume of the desolidification and impurity removal units, generate no byproducts other than solid particles, achieve high oil slurry utilization, and is economical and environmentally friendly. It is especially suitable for treating heavy oil slurries with high sulfur and nitrogen content.

Claims

1. A method for desolidifying oil slurry, characterized in that, The method includes: (1) Extraction is performed by contacting an organic solvent with a catalytic oil slurry to obtain an upper raffinate phase 1 and a lower extract phase 1, wherein the mass ratio of the organic solvent to the catalytic oil slurry is not less than 0.5; (2) After removing solids and organic solvents from raffinate phase 1, raffinate oil is obtained. The removed organic solvents are returned to step (1) for extraction. The organic solvents are selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide and sulfolane.

2. The method according to claim 1, characterized in that, The mass ratio of the organic solvent to the catalytic slurry is (0.5-3):

1.

3. The method according to claim 1 or 2, characterized in that, After removing solids and organic solvents from extraction phase 1, a desoldered oil slurry enriched with aromatics is obtained. The removed organic solvents are returned to step (1) for extraction.

4. The method according to claim 3, characterized in that, The step of obtaining an aromatic-enriched desoldered slurry after the extraction phase 1 removes solids and organic solvent by a mass ratio of organic solvent to catalytic slurry of no more than 1:1 includes: Extraction phase 1 is desolventized to obtain extraction phase 2. Extraction phase 2 is desolventized to obtain aromatic-enriched desolventized oil slurry. The organic solvent removed from extraction phase 2 is reused.

5. The method according to claim 3, characterized in that, The step of obtaining an aromatic-enriched desolventized slurry after the extraction phase 1 removes solids and organic solvent, with the organic solvent mass ratio being higher than 1:1, includes: Extraction phase 1 is desolventized to obtain extraction phase 3. Extraction phase 3 is desolventized by removing solids and organic solvents to obtain aromatic-enriched desolventized oil slurry. The organic solvents removed from extraction phase 1 are returned to the extraction tower for reuse.

6. The method according to claim 5, characterized in that, The portion of the extract phase 3 after solid removal is returned to the catalytic slurry for re-extraction.

7. The method according to claim 6, characterized in that, The viscosity of the extract phase 3 is 1-150 mm. 2 .s.

8. The method according to claim 1 or 2, characterized in that, The extraction conditions include: Temperatures range from 25 to 130°C; and / or The time is 10-60 minutes; and / or The extraction contact method is countercurrent contact.

9. The method according to claim 1 or 2, characterized in that, The temperature at which the raffinate phase 1 is deconsolidated is lower than the extraction temperature, and / or The desolidification time is 0.5-4 hours.

10. The method according to claim 9, characterized in that, The temperature at which the raffinate phase 1 is desolidified is 0-60℃.

11. The method according to claim 1 or 2, characterized in that, Deconsolidation of the raffinate phase 1 is carried out in a settling separator with a narrowed bottom; and / or The time for desolidification of the raffinate phase 1 is 2-8 hours.

12. The method according to claim 1 or 2, characterized in that, The method for removing solids from the extraction phase 1 is selected from one of cross-flow membrane filtration, dead-end filtration, and settling.

13. The method according to claim 12, characterized in that, The cross-flow membrane filter has a membrane pore size of 0.1-50 μm.

14. The method according to claim 1 or 2, characterized in that, The method for removing organic solvent from the extraction phase 1 is selected from one or more of flash distillation, vacuum distillation, stripping distillation and molecular distillation.

15. The method according to claim 1 or 2, characterized in that, By weight, the catalytic slurry contains: 15-65% saturated components, 25-65% aromatic components, 8-20% gums, 1-8% asphaltenes; and / or The solid content of the catalytic slurry is 1500-5000 ppm.

16. The method according to claim 1 or 2, characterized in that, Before the catalytic slurry comes into contact with the organic solvent, membrane separation is also included, including: membrane separation of the slurry raw material to obtain a clarified slurry and a concentrated catalytic slurry, wherein the pore size of the membrane is less than 0.2 μm; the concentrated catalytic slurry is desolidified according to the method of claim 1, wherein the organic solvent is removed from the extraction phase 1, the organic solvent and the extracted oil are separated, the removed organic solvent is returned to step (1) for extraction, and the extracted oil is returned to the membrane separation step.

17. The method according to claim 16, characterized in that, The membrane has a pore size of 0.1-0.2 μm; and / or The single-pass throughput of clarified oil slurry is 70-90%.

18. The method according to claim 16, characterized in that, The solid content of the catalytic slurry is 1800-6000 ppm; and / or The catalytic slurry is selected from catalytic cracking slurry, and the catalytic slurry contains: 15-65% saturated components, 25-65% aromatic components, 8-20% gum, and 1-8% asphaltenes.

19. The method according to claim 16, characterized in that, The saturated fraction in the concentrated catalytic slurry is mainly alkanes, and the residual oil is returned to the catalytic cracking unit for reprocessing by stripping distillation or vacuum distillation; or The saturated fraction in the concentrated catalytic slurry is mainly cycloalkanes, and the raffinate is mixed with the extraction phase for further processing.

20. A method for removing solids and impurities from oil slurry, characterized in that, The method includes: Step 1: Separate the catalytic oil slurry into light components and heavy components according to temperature; Step 2: Selectively hydrogenate the light components according to their sulfur content; Step 3: The catalytic oil slurry heavy components are mixed with an organic solvent to form a mixed heavy component. The organic solvent is selected from one or more of furfural, DMF, N-methylpyrrolidone, dimethyl sulfoxide, and sulfolane. Step 4: Filter and settle the mixed heavy components to obtain a permeate side component and a concentration side component. Mix the concentration side component with the heavy components and an organic solvent. Remove the solvent from the permeate side component to obtain the filtered slurry heavy components. Hydrogenate the filtered slurry heavy components to obtain hydrogenated slurry heavy components. Complete the selective deconsolidation and impurity removal pretreatment of the slurry.

21. The method according to claim 20, characterized in that, In step 1, The fractionation is achieved by distillation, and the fractionation is based on a temperature of 400-480°C; and / or In step 2, light components with a sulfur content greater than 3000 pppm are subjected to hydrogenation treatment.

22. The method according to claim 20, characterized in that, In step 2, The hydrogenation treatment temperature is 300-330℃, and the hydrogenation treatment pressure is 2-4 MPa; and / or The active components of the catalysts used in the hydrogenation treatment of step 2 and / or step 3 are each selected from Group VIB and / or Group VIII; the active components account for more than or equal to 1.0% of the mass of the catalyst in terms of elemental content.

23. The method according to claim 20, characterized in that, In step 3, The mass ratio of the organic solvent to the heavy component is 0.5-3:1; and / or The mixing temperature is 20-130℃.

24. The method according to claim 20, characterized in that, Step 3, the process of filtering and settling the mixed heavy components to obtain the permeate-side component and the concentrated-side component includes: The mixed heavy components are filtered to obtain a permeation side component and a concentration side component. The concentration side component is subjected to sedimentation and solidification to separate solid particles. The sedimented and solidified concentration side component is then mixed with the heavy components and an organic solvent. Alternatively, the mixed heavy components are subjected to sedimentation and desolidification to separate solid particles. The sedimented mixed heavy components are then filtered to obtain permeate-side and concentration-side components. The concentration-side components are then mixed with the heavy components and an organic solvent.

25. The method according to claim 20, characterized in that, In step 4, The settling time for the settling and deconsolidation is 10 min-60 min; and / or The filtration method includes dead-end filtration and / or cross-flow membrane filtration; the membrane material of the cross-flow membrane filtration includes one or more of alumina, metal, and silicon carbide.

26. The method according to claim 20, characterized in that, In step 4, The filtration process employs either primary or secondary filtration. The material used in the primary filtration has a pore size ≤ 0.5 μm; The secondary filtration includes a first-stage filtration and a second-stage filtration. The material used in the first-stage filtration has a pore size ≤ 0.5 μm, and the material used in the second-stage filtration has a pore size ≤ 0.1 μm.

27. The method according to claim 20, characterized in that, In step 4, In step 4, the solids concentration in the heavy components of the filtered oil slurry after primary filtration and solvent removal is ≤50ppm; the solids concentration in the heavy components of the filtered oil slurry after secondary filtration and solvent removal is ≤20ppm.

28. The method according to claim 20, characterized in that, In step 4, The hydrogenation process can be a one-step hydrogenation process or a two-step hydrogenation process; The temperature of the one-step hydrogenation process is 340-380℃, and the pressure is 4-8MPa. The two-step hydrogenation process includes a first-step hydrogenation process and a second-step hydrogenation process; the temperature of the first-step hydrogenation process is 300-330℃, and the pressure of the first-step hydrogenation process is 2-4MPa; the temperature of the second-step hydrogenation process is 320-350℃, and the pressure of the second-step hydrogenation process is 3-5MPa.

29. The method according to claim 20, characterized in that, Step 4 also includes mixing the solvent removed from the permeation side with the heavy component and the organic solvent to form a mixed heavy component.

30. The method according to claim 20, characterized in that, The method further includes: step 5, mixing the light component obtained in step 2 and the hydrogenated oil slurry heavy component obtained in step 4 to form a refined oil slurry.

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