A process for the hydroconversion of full range ethylene tar with solvent addition

Abstract

The present application adds a solvent containing a hydrogen donor and a dispersant in full-range ethylene tar, and carries out desulfurization and deasphaltene hydrogenation conversion reaction under the synergistic action of catalyst FHUDS-6 and hydrogen, to obtain hydrogenation tail gas and generated oil. The present application can not only disperse asphaltene components in ethylene tar, prevent asphaltene from gathering and depositing coking, increase the solubility in ethylene tar, and make asphaltene soft, but also can improve the catalyst activity under the synergistic action of solvent, hydrogen and hydrogenation catalyst, thereby superimposing and efficiently hydrogenating and converting asphaltene components in ethylene tar, and breaking through the limitation of fixed-bed hydrogenation process of poor oil on the asphaltene content index in the raw material. The present application has the advantages of mild process conditions, high deasphaltene rate, low catalyst coking rate, slow deactivation, reduced energy consumption, good storage stability and compatibility of hydrogenation generated oil, and opens up a technical approach for efficient hydrogenation conversion of full-range ethylene tar.

Description

Technical Field

[0001] This invention relates to the field of hydrogenation of inferior oil products, and more specifically to a method for hydrogenation conversion of ethylene tar with added solvent. Background Technology

[0002] The development of the "large-scale ethylene" industry and the increasing degree of crude oil refining have led to a continuous increase in the production of ethylene tar, a byproduct of the secondary reaction of ethylene steam cracking, reaching approximately 5 million tons in 2020. Ethylene tar is rich in polycyclic aromatic hydrocarbons and fused-ring aromatic hydrocarbons, with high calorific value and carbon-hydrogen ratio, and low sulfur, nitrogen, heavy metal content, and ash content. The tar content above 350℃ accounts for more than 60wt% of the distillate composition, which is complex in composition, dense, has a strong odor, high asphaltenes content, poor storage stability, and poor compatibility with other heavy oil components, classifying it as a low-quality heavy distillate oil.

[0003] The research processes for processing and utilizing ethylene tar can be summarized into three categories: (1) Processes primarily aimed at producing fine and organic chemical raw materials, such as producing carbon black using high-temperature cracking as the main process, extracting and refining naphthalene products using distillation as the main process, preparing petroleum resins using thermal polymerization, and producing pitch carbon fiber and needle coke using carbonization condensation as the main process; (2) Processes primarily aimed at coking and gasification in refining enterprises, introducing ethylene tar blending into the coking unit of petroleum refining, and introducing ethylene tar as part of the syngas into the butanol and octanol unit of coal chemical industry, which not only solves the problem of tar outlet, but also maximizes the benefits of refining and chemical industry; (3) Processes primarily aimed at fixed-bed hydrogenation in petroleum refining, based on the characteristics of poor-quality heavy fractions of ethylene tar, cutting the oil into light and heavy fractions, and then producing aromatic solvent oils or blending components of gasoline and diesel through hydrogenation refining and hydrogenation cracking processes respectively.

[0004] The first two processes mentioned above have small processing capacities, are complex, and have high production costs, thus they have not been widely used in industry. Currently, ethylene tar is mainly used for fuel oil combustion, which has the disadvantage of causing serious environmental pollution. In the future, it will be treated as hazardous waste. The efficient utilization of ethylene tar is of great significance for solving energy supply problems, expanding energy fuel pathways, improving the overall economic and environmental benefits of ethylene plants, and even increasing refining capacity.

[0005] Fixed-bed hydrocracking of heavy oil is a mature technology with low investment, and is an important means of upgrading and lightening heavy oil. However, its application is limited by the feedstock, and it can only process heavy feedstocks with an asphaltene content typically not exceeding 5%. With the increasing trend of crude oil deterioration and heavyening, fluidized-bed and slurry-bed hydrocracking technologies have been developed and industrialized, overcoming the feedstock limitations of conventional heavy oil hydrocracking technologies and achieving efficient conversion of asphaltene. However, regardless of the hydrocracking process used, the process conditions for heavy oil hydrocracking are extremely demanding, requiring high temperature and pressure. Temperatures typically exceed 380℃, sometimes even reaching over 400℃, and pressures are above 10MPa.

[0006] Based on existing understanding of hydrogenation technology for low-quality heavy oil, in fixed-bed hydrogenation processes for producing fuel oil blending components from ethylene tar, the light fraction of ethylene tar is typically hydrogenated separately at suitable cut points to produce gasoline and diesel fuel oil products. The heavy fraction, due to its complex composition and high asphaltenes content, cannot be processed using efficient and cost-effective hydrogenation technologies (such as patent CN101724458A, a method for hydrogenating ethylene tar). Currently, there are no reports in existing technologies on the efficient fixed-bed hydrogenation conversion of the entire ethylene tar fraction to prepare hydrogenated product oil with low asphaltenes content. Summary of the Invention

[0007] The purpose of this invention is to improve the efficiency of existing ethylene tar processing and utilization by finding a technical route for the fixed-bed hydroconversion of full-fraction ethylene tar. The inventors unexpectedly discovered in experiments that adding a special solvent containing a hydrogen donor to full-fraction ethylene tar not only disperses the asphaltenes in the ethylene tar, preventing asphaltenes from agglomerating and depositing, and increasing their solubility in the ethylene tar, thus softening the asphaltenes, but also enhances catalyst activity through the synergistic effect of the solvent, hydrogen, and a specific catalyst. This results in highly efficient hydroconversion of the asphaltenes in the ethylene tar, overcoming the limitations imposed by fixed-bed hydroconversion processes on the asphaltenes content in feedstocks for low-quality oils. This invention offers advantages such as milder process conditions, high deasphalting rate, low catalyst coking rate and slow deactivation, reduced energy consumption, and good storage stability and compatibility of the hydrogenated oil, thus opening up a highly efficient technical route for the hydroconversion of full-fraction ethylene tar.

[0008] This invention overcomes the shortcomings of existing technologies, such as the high difficulty in processing and utilizing ethylene tar as a whole, low utilization rate, low economic benefits, harsh conditions and complex steps in the hydrogenation process, and low conversion rate of inferior components like asphaltenes. The technical solution adopted in this invention is: a method for the hydrogenation conversion of full-fraction ethylene tar with added solvent, including a feedstock preheating stage, a hydrogenation reaction stage, and an oil-gas separation stage, as detailed below:

[0009] (1) Feed preheating stage of raw material oil: After the ethylene tar is mixed with the solvent, it is filtered by the filter and then pumped out by the booster pump and transported into the feed pipeline. It is then mixed with hydrogen and enters the preheating section of the reactor. The solvent is composed of a hydrogen supply agent and a dispersant. The hydrogen supply agent is a highly aromatic oil and the dispersant is an SFH type hydrogenation scale inhibitor.

[0010] (2) Hydrogenation reaction stage: The oil and gas mixture that has been preheated in step (1) enters the hydrogenation reactor and undergoes a hydrogenation conversion reaction under the synergistic effect of solvent, hydrogen and catalyst to achieve desulfurization and deasphalting.

[0011] (3) Oil-gas separation stage: The hydrogenation reaction effluent in step (2) enters the high and low pressure separation tanks in sequence for gas-liquid separation to obtain hydrogenation tail gas and generated oil.

[0012] Further, the solvent mentioned in step (1) accounts for 0.01% to 2% of the mass fraction of ethylene tar; the solvent mainly consists of a hydrogen donor containing 50% to 90% by mass and a dispersant containing 10% to 50% by mass; the highly aromatic oil contains more than 70 wt% of aromatic components; and the aromatic components contain more than 40 wt% of cycloalkyl aromatic hydrocarbon components.

[0013] Further, the solvent in step (1) accounts for 0.05% to 1.5% of the mass fraction of ethylene tar; the mass percentage of hydrogen donor in the solvent is 60% to 75%, and the mass percentage of dispersant is 25% to 40%; the highly aromatic oil contains more than 75 wt% of aromatic components; and the aromatic components contain more than 45 wt% of cycloalkyl aromatic hydrocarbon components.

[0014] Further, the operating conditions for the raw material feeding preheating stage in step (1) are as follows: the mixing temperature of the solvent and ethylene tar is 50℃~95℃, the pressure of the raw material oil after pump pressurization is 0.1MPa~0.5MPa, the pressure of the mixture of ethylene tar and hydrogen is 3.5MPa~8.5MPa, and the temperature of the preheating section of the reactor is 200℃~285℃.

[0015] Furthermore, the ethylene tar originates from an ethylene plant, has a distillation range of 170℃ to 650℃, and contains 18wt% to 35wt% asphaltenes and less than 0.3wt% sulfur. The highly aromatic oil is selected from C10 from a low-quality heavy aromatics light processing unit. + The high-aromatic oil has a distillation range of 280℃ to 510℃ and is a mixture of one or more of the following: low-quality heavy aromatic feedstock or its hydrotreated oil, catalytic cracking heavy cycle oil or its hydrotreated oil;

[0016] Furthermore, the distillation range of ethylene tar is 180℃~640℃; the distillation range of highly aromatic oil is 330℃~460℃.

[0017] Furthermore, the operating conditions for the hydrogenation reaction stage in step (2) are as follows: reaction temperature of 200℃~400℃, reaction pressure of 2MPa~15MPa, and volume hourly space velocity of 0.2h. -1 ~1.5h -1 The hydrogen-to-oil volume ratio is 200–1000.

[0018] Furthermore, the operating conditions for the hydrogenation reaction stage in step (2) are: reaction temperature of 230℃~380℃, reaction pressure of 4MPa~10MPa, and volume hourly space velocity of 0.5h. -1 ~1.3h -1 The hydrogen-to-oil volume ratio is 300–800.

[0019] Furthermore, the hydrogenation reactor in step (2) is one of an isothermal fixed-bed reactor, a fluidized bed reactor, or a suspended bed reactor; the hydrogenation catalyst is selected from a hydrogenation and de-impurity refining catalyst in a residue oil or diesel hydrogenation treatment reactor.

[0020] Further, in the oil-gas separation stage described in step (3), the hydrogenation reaction effluent enters a high-pressure separator for primary separation. After primary separation, the liquid flowing out from the bottom of the high-pressure separator enters a low-pressure separator for secondary separation. After the material is separated in the low-pressure separator, the gas at the top and the gas separated at the top of the high-pressure separator are combined to form hydrogenation tail gas for gas sampling or discharge. The liquid at the bottom of the low-pressure separator is stripped with hydrogen to obtain hydrogenated oil. The distillation range of the hydrogenated oil is 60℃~580℃, preferably 65℃~520℃.

[0021] The relevant principles in this invention:

[0022] The asphaltenes in ethylene tar undergo free radical polymerization during the feeding process of the hydroconversion process via free radicals or metal catalysis. Especially during the preheating stage of the feedstock before entering the hydroconversion reactor, the increased temperature leads to strong self-polymerization and association reactions, which increases the molecular weight of the asphaltenes and forms layered self-polymer particles similar to carbon structures. This not only makes it difficult for the asphaltenes in ethylene tar to undergo subsequent catalytic hydroconversion reactions, reducing the hydroreconversion effect of ethylene tar, but also easily causes coking and deposition in pipelines and catalyst deactivation.

[0023] In this invention, a solvent is mixed with ethylene tar. The dispersant and hydrogen donor in the solvent interact with the asphaltenes in the ethylene tar, preventing the asphaltenes from undergoing self-polymerization during feeding. Simultaneously, the synergistic effect of the hydrogen donor and hydrogen in the solvent generates a hydrogen donor, supplying hydrogen radicals to the asphaltenes and preventing high-temperature condensation reactions of asphaltenes molecules during the preheating stage. Feeding the feedstock with a solvent-ethylene tar mixture allows the asphaltenes to soften under the influence of the solvent components during the feeding and preheating stages, becoming a soft, resinous asphalt. This increases the solubility of the asphaltenes in the ethylene tar, thereby improving the hydroconversion performance of the feedstock.

[0024] In the method of this invention, the preheated mixture of feedstock oil and hydrogen softens the asphalt, increasing its solubility in the feedstock oil and making it easier for the feedstock oil and gas to undergo hydroconversion reaction. Furthermore, during the reaction stage in the hydroconversion reactor, the solvent, hydrogen, and the multi-component hydroconversion catalyst in the reactor further synergistically enhance the effect, allowing the feedstock oil and catalyst to provide more active hydrogen and reactive sites, thereby improving the catalyst's reaction performance. Ethylene tar exhibits a higher desulfurization and deasphalting conversion rate under milder conditions.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention provides a method for the hydroconversion of full-fraction ethylene tar with added solvent. This method can improve the efficiency of existing ethylene tar processing and utilization, and opens up a technical route for the fixed-bed hydroconversion of full-fraction ethylene tar.

[0027] 2. In the full-fraction ethylene tar hydroconversion method of the present invention, a solvent composed of a hydrogen donor and a dispersant is added to the ethylene tar feedstock during the feed preheating stage to prevent the asphaltenes in the ethylene tar from undergoing self-polymerization and association reactions during feed transportation. Simultaneously, the various components of the solvent prevent the high-temperature condensation reaction of asphaltenes molecules during the feedstock preheating process. This invention not only reduces the aggregation, deposition, and coking of asphaltenes in pipelines but also softens the asphaltenes, increasing the solubility of asphaltenes in ethylene tar, thereby improving the hydroconversion performance of the feedstock.

[0028] 3. In the solvent-added full-fraction ethylene tar hydroconversion method of the present invention, during the hydroconversion reaction stage, the solvent, hydrogen, and the multi-component hydroconversion catalyst in the reactor further synergistically enhance the catalyst's reactivity by providing more active hydrogen and reactive sites to the feedstock and catalyst. The preheated feedstock and hydrogen mixture softens the asphaltenes, increasing their solubility in the feedstock and making the feedstock gas more readily available for hydroconversion. Therefore, the present invention enables ethylene tar to achieve higher desulfurization and deasphalting conversion rates under milder conditions. Detailed Implementation

[0029] The feedstock used in the experiment was ethylene tar, a byproduct of the ethylene plant. The properties of the feedstock are shown in Table 1. The catalyst used in the experiment was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation.

[0030] The highly aromatic oil used in the experiment was derived from C10 of a low-quality heavy aromatics processing unit. + The feedstock oil is of inferior quality and contains heavy aromatic hydrocarbons. The solvent used has a high aromatic oil component in a mass ratio of 65:35 to the SFH type hydrogenated scale inhibitor.

[0031] Table 1 Properties of Ethylene Tar Feedstock

[0032] project Ethylene tar feedstock <![CDATA[Kinematic viscosity (50 °C) / mm 2 ·s -1 > 857.1 <![CDATA[Density (15 °C) / kg·m -3 > 1.0925 Sulfur content / wt% 0.115 Asphalt / wt% 30.6 Distillation range / ℃ Initial boiling point 180 10％ / 30％ 359 / 487 50％ / 90％ 503 / 540 Dry 640 Cleanliness 5

[0033] The present invention will be further described below with reference to specific embodiments.

[0034] Example 1

[0035] Ethylene tar from Table 1 was used as feedstock and mixed with a solvent at a concentration of 1.0 wt% of the feedstock oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 45% was cycloalkyl aromatic hydrocarbons. The solvent and feedstock oil were mixed at 75°C, then pumped under pressure to a feed line at 0.2 MPa. The mixture was then mixed with hydrogen and introduced into the preheating section of the reactor at 200°C. During the hydrogenation reaction, the preheated feedstock oil-gas mixture entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. 1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0036] Example 2

[0037] Ethylene tar from Table 1 was used as feedstock and mixed with a solvent at a concentration of 1.0 wt% of the feedstock oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 70%, of which 40% was cycloalkyl aromatic hydrocarbons. The solvent and feedstock oil were mixed at 75°C, then pumped under pressure and transported through the feed pipeline to a pressure of 0.2 MPa. The mixture was then mixed with hydrogen and introduced into the preheating section of the reactor at 200°C. During the hydrogenation reaction, the preheated feedstock oil-gas mixture entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. 1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0038] Example 3

[0039] Ethylene tar from Table 1 was used as raw material and mixed with a solvent at a concentration of 1.5 wt% of the raw material oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 45% was cycloalkyl aromatic hydrocarbons. The mixing temperature was 85°C. After being pressurized by a pump, the mixture was extracted and transported into the feed pipeline at a pressure of 0.3 MPa. It was then mixed with hydrogen and introduced into the preheating section of the reactor at a temperature of 195°C. During the hydrogenation reaction, the preheated raw material oil and gas entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 330°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0040] Example 4

[0041] Ethylene tar from Table 1 was used as raw material and mixed with a solvent at a concentration of 0.5 wt% of the raw material oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 45% was cycloalkyl aromatic hydrocarbons. The mixing temperature was 90°C. After being pressurized by a pump, the mixture was extracted and transported into the feed pipeline at a pressure of 0.4 MPa. It was then mixed with hydrogen and introduced into the preheating section of the reactor at a temperature of 190°C. During the hydrogenation reaction, the preheated raw material oil and gas entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 350°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0042] Example 5

[0043] Ethylene tar from Table 1 was used as raw material and mixed with a solvent at a concentration of 0.05 wt% of the raw material oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 45% was cycloalkyl aromatic hydrocarbons. The mixing temperature was 80°C. After being pressurized by a pump, the mixture was extracted and transported into the feed pipeline at a pressure of 0.1 MPa. It was then mixed with hydrogen and introduced into the preheating section of the reactor at a temperature of 200°C. During the hydrogenation reaction, the preheated raw material oil and gas entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 320°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0044] Example 6

[0045] Ethylene tar from Table 1 was used as raw material and mixed with a solvent at a concentration of 1.0 wt% of the raw material oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 45% was cycloalkyl aromatic hydrocarbons. The mixing temperature was 75°C. After being pressurized by a pump, the mixture was extracted and transported into the feed pipeline at a pressure of 0.2 MPa. It was then mixed with hydrogen and introduced into the preheating section of the reactor at a temperature of 200°C. During the hydrogenation reaction, the preheated raw material oil and gas entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 4 MPa, and volume hourly space velocity (VHSV) 0.5 h⁻¹. -1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0046] Comparative Example 1

[0047] Ethylene tar from Table 1 is used as feedstock. After being pressurized by a pump, it is extracted and transported through the feed pipeline. The feedstock temperature is 75℃, and the pressure after pressurization is 0.2 MPa. It is then mixed with hydrogen and fed into the preheating section of the reactor at a temperature of 200℃. During the hydrogenation reaction, the preheated feedstock gas enters the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction are: reaction temperature 340℃, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0048] Comparative Example 2

[0049] Ethylene tar from Table 1 is used as feedstock. After being pressurized by a pump, it is extracted and transported through the feed pipeline. The feedstock temperature is 75℃, and the pressure after pressurization is 0.2 MPa. It is then mixed with hydrogen and fed into the preheating section of the reactor at a temperature of 200℃. During the hydrogenation reaction, the preheated feedstock gas enters the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction are: reaction temperature 340℃, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 0.5 h⁻¹. -1The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0050] Comparative Example 3

[0051] Ethylene tar from Table 1 was used as feedstock and mixed with a solvent at a concentration of 1.0 wt% of the feedstock oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 75%, of which 35% was cycloalkyl aromatic hydrocarbons. The solvent and feedstock oil were mixed at 75°C, then pumped under pressure and transported through the feed pipeline to a pressure of 0.2 MPa. The mixture was then mixed with hydrogen and introduced into the preheating section of the reactor at 200°C. During the hydrogenation reaction, the preheated feedstock oil-gas mixture entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. 1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0052] Comparative Example 4

[0053] Ethylene tar from Table 1 was used as feedstock and mixed with a solvent at a concentration of 1.0 wt% of the feedstock oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 65%, of which 45% was cycloalkyl aromatic hydrocarbons. The solvent and feedstock oil were mixed at 75°C, then pumped under pressure and transported through the feed pipeline to a pressure of 0.2 MPa. The mixture was then mixed with hydrogen and introduced into the preheating section of the reactor at 200°C. During the hydrogenation reaction, the preheated feedstock oil-gas mixture entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. 1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0054] Comparative Example 5

[0055] Ethylene tar from Table 1 was used as feedstock and mixed with a solvent at a concentration of 1.0 wt% of the feedstock oil. The solvent was a highly aromatic oil with an aromatic hydrocarbon content of 65%, of which 35% was cycloalkyl aromatic hydrocarbons. The solvent and feedstock oil were mixed at 75°C, then pumped under pressure and transported through the feed pipeline to a pressure of 0.2 MPa. The mixture was then mixed with hydrogen and introduced into the preheating section of the reactor at 200°C. During the hydrogenation reaction, the preheated feedstock oil-gas mixture entered the fixed-bed hydrogenation reactor. The operating conditions for the hydrogenation reaction were: reaction temperature 340°C, reaction pressure 5 MPa, and volume hourly space velocity (VHSV) 1.0 h⁻¹. 1 The hydrogen-to-oil volume ratio was 400:1, and the catalyst used in the fixed-bed reactor was FHUDS-6, developed by the Dalian Petrochemical Research Institute of China Petroleum & Chemical Corporation. During the oil-gas separation process, the hydrogenation reaction effluent sequentially entered high- and low-pressure separators for gas-liquid separation. The liquid was extracted to obtain hydrogenation tail gas and product oil. The reaction results are shown in Table 2.

[0056] As shown in Table 2, the deasphalting rate of ethylene tar in the full-fraction hydroconversion method of the present invention, with the addition of solvent, increases from below 60 wt% to over 70 wt%, with the best embodiment even reaching over 80 wt%; the desulfurization rate also shows the same trend. This indicates that the addition of a special solvent containing a hydrogen donor in the present invention not only disperses the asphaltenes in ethylene tar, preventing asphaltenes from agglomerating, depositing, and coking, and increasing their solubility in ethylene tar, thus softening the asphaltenes, but also enhances the catalyst activity under the synergistic effect of the solvent, hydrogen, and hydrogenation catalyst. This results in highly efficient hydroconversion of the asphaltenes in ethylene tar, overcoming the limitations imposed by fixed-bed hydroconversion processes on the asphaltenes content in feedstocks for low-quality oils. It has the advantages of high desulfurization and deasphalting rates, and the oil quality is significantly improved.

[0057] Table 3 shows the cycle time for cleaning filters and pipeline blockages during the experiment, as well as the analysis results of catalyst carbonization. As can be seen from Table 3, the solvent-added full-fraction ethylene tar hydroconversion method of this invention has significant technical advantages over traditional hydrogenation methods for the deep conversion of ethylene tar, considering both the cycle time for cleaning filters and pipeline blockages and the results of catalyst carbonization. This provides a good technical means to improve the overall value of low-quality ethylene tar feedstock.

[0058] Table 2 Experimental operating conditions and properties of hydrogenated oil

[0059]

[0060] Table 3. Experimental shutdown and decoking cycle and catalyst carbonization analysis results.

[0061]

Claims

1. A method for the hydroconversion of full-fraction ethylene tar, characterized in that, The method includes: (1) Feed preheating stage of raw material oil: After the ethylene tar is mixed with the solvent, it is filtered by the filter and then pumped out by the booster pump and transported into the feed pipeline. It is then mixed with hydrogen and enters the preheating section of the reactor. The solvent is composed of a hydrogen supply agent and a dispersant. The hydrogen supply agent is a highly aromatic oil and the dispersant is an SFH type hydrogenation scale inhibitor. (2) Hydrogenation reaction stage: The oil and gas mixture that has been preheated in step (1) enters the hydrogenation reactor and undergoes a hydrogenation conversion reaction under the synergistic effect of solvent, hydrogen and catalyst to achieve desulfurization and deasphalting. (3) Oil-gas separation stage: The hydrogenation reaction effluent in step (2) enters the high and low pressure separation tanks in sequence for gas-liquid separation to obtain hydrogenation tail gas and generated oil; The solvent mentioned in step (1) accounts for 0.01% to 2% of the mass fraction of ethylene tar; the mass percentage of hydrogen donor in the solvent is 50% to 90%, and the mass percentage of dispersant is 10% to 50%; the highly aromatic oil contains more than 70 wt% of aromatic components; and the aromatic components contain more than 40 wt% of cycloalkyl aromatic hydrocarbon components.

2. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, The solvent mentioned in step (1) accounts for 0.05% to 1.5% of the mass fraction of ethylene tar; the mass percentage of hydrogen donor in the solvent is 60% to 75%, and the mass percentage of dispersant is 25% to 40%; the highly aromatic oil contains more than 75 wt% of aromatic components; and the aromatic components contain more than 45 wt% of cycloalkyl aromatic hydrocarbon components.

3. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, The operating conditions for the feedstock preheating stage in step (1) are as follows: the mixing temperature of the solvent and ethylene tar is 50℃~95℃, the pressure of the feedstock after pump boosting is 0.1MPa~0.5MPa, the pressure of the ethylene tar mixed with hydrogen is 3.5MPa~8.5MPa, and the temperature of the preheating section of the reactor is 200℃~285℃.

4. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, The ethylene tar is derived from an ethylene plant, has a distillation range of 170°C to 650°C, and has an asphaltene content of 18 wt% to 35 wt% and a sulfur content of less than 0.3 wt%; the high aromatic oil is selected from C10 + one or more mixtures of inferior heavy aromatic feedstock or its hydrotreated oil, catalytic cracking heavy cycle oil or its hydrotreated oil; the high aromatic oil has a distillation range of 280°C to 510°C.

5. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 4, characterized in that, The distillation range of ethylene tar is 180℃~640℃; the distillation range of highly aromatic oil is 330℃~460℃.

6. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, The operating conditions for the hydrogenation reaction stage in step (2) are: reaction temperature of 200℃~400℃, reaction pressure of 2MPa~15MPa, and volume hourly space velocity of 0.2h. -1 ~1.5h -1 The hydrogen-to-oil volume ratio is 200–1000.

7. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 6, characterized in that, The operating conditions for the hydrogenation reaction stage in step (2) are: reaction temperature of 230℃~380℃, reaction pressure of 4MPa~10MPa, and volume hourly space velocity of 0.5h. -1 ~1.3h -1 The hydrogen-to-oil volume ratio is 300–800.

8. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, The hydrogenation reactor mentioned in step (2) is one of an isothermal fixed bed reactor, a fluidized bed reactor, or a suspended bed reactor; the catalyst is selected from a hydrogenation and purification reactor for residual oil or diesel oil.

9. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 1, characterized in that, In the oil-gas separation stage described in step (3), the hydrogenation reaction effluent enters a high-pressure separator for primary separation. After primary separation, the liquid flowing out from the bottom of the high-pressure separator enters a low-pressure separator for secondary separation. After the material is separated in the low-pressure separator, the gas at the top and the gas separated at the top of the high-pressure separator are combined to form hydrogenation tail gas for gas sampling or discharge. The liquid at the bottom of the low-pressure separator is stripped with hydrogen to obtain hydrogenated oil. The distillation range of the hydrogenated oil is 60℃~580℃.

10. The method for hydrogenating and converting full-fraction ethylene tar as described in claim 9, characterized in that, The distillation range of the hydrogenated oil is 65℃~520℃.

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