Process for refining high-value utilization of naphthenic or intermediate base lubricating oil fraction components

Abstract

The application relates to a process for refining and high-value utilization of a naphthenic or intermediate base lubricating oil fraction component, and belongs to the field of petroleum refining. In the first step, a naphthenic or intermediate base lubricating oil fraction is subjected to complex de-naphthenic acid at a catalyst-oil ratio of 0.1-5:1 to obtain a high-purity naphthenic acid product and a de-acidified lubricating oil fraction; in the second step, the de-acidified lubricating oil fraction is subjected to step-by-step hydrofining to remove sulfur, nitrogen and oxygen heteroatoms and to saturate aromatic hydrocarbons, to obtain a high-naphthenic base hydrogenated fraction oil; in the third step, the high-naphthenic base hydrogenated oil is subjected to vacuum precise fractionation to obtain a series of lubricating oil narrow fractions; and in the fourth step, the lubricating oil narrow fractions are subjected to urea complex dewaxing at a catalyst-oil ratio of 1-10:1 to obtain a refined industrial wax product and a low-freezing lubricating oil base oil, which is used for producing transformer oil, rubber filling oil, low-freezing grease or low-freezing lubricating oil.

Description

Technical Field

[0001] This invention provides a process for the fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillates, relating to the field of petroleum refining. Background Technology

[0002] Naphthenic crude oil is an indispensable and scarce high-quality resource for producing high-end specialty oils such as ultra-low pour point lubricating oil, ultra-high voltage transformer oil, ultra-low pour point refrigeration oil, environmentally friendly rubber oil, and high-performance asphalt. It holds significant strategic importance for industries such as national defense, aerospace, and power. The explosive growth of new energy vehicles is forcing the refining industry to transform and upgrade from a "fuel-based" to a "chemical-based and specialty oil" model. However, the "oil-to-specialty" conversion of naphthenic crude oil faces several challenges: ① Difficulty in differentiation: the wide or overlapping range of petroleum distillation fractions makes it difficult to meet the requirements of high-end specialty oils, resulting in lubricating oil resource utilization rates below 50% and difficulties in controlling asphalt production; ② Poor adaptability: existing refining processes can only reliably produce high-quality lubricating oil and asphalt from high-quality crude oil. Therefore, there is an urgent need to develop new molecular refining technologies to enable the production of high-end specialty oils from both naphthenic crude oil and intermediate-base crude oil.

[0003] Compared to lubricating base oils, high-purity naphthenic acids are priced 10,000-50,000 RMB / ton higher, and specialty industrial waxes are 03,000-10,000 RMB / ton higher. Both are important fine chemical raw materials with wide applications, especially naphthenic acids, which are invaluable high-quality grease-forming agents for lubricating greases. However, the most advanced lubricating oil fraction hydrorefining technology, while overcoming the shortcomings of the traditional three-step process (solvent dewaxing → solvent refining → clay supplementary refining) which is complex, has significant yield losses and pollution, still faces challenges. Given the crucial difference between paraffinic and naphthenic crude oils—the significant difference in naphthenic acid and wax content—hydrogenating and deoxygenating naphthenic acids to generate hydrocarbons and isomerizing and hydrogenating waxes to lower the pour point, requires substantial hydrogen consumption, increases costs, is difficult to control, and results in inconsistent oil source availability. Furthermore, the oil source is limited to specific naphthenic crude oils, preventing the use of intermediate-based crude oils and wasting valuable and scarce resources such as naphthenic acids and waxes. Therefore, there is an urgent need to develop a lubricating oil fraction refining technology that can adapt to a wider and more varied oil source, enabling the clean, efficient, and high-value utilization of all components. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing lubricating oil fraction refining technologies by proposing a high-value utilization process for the fractional refining of naphthenic or intermediate-based lubricating oil fractions. After recovering naphthenic acids through complexation and deacidification of lubricating oil fractions, the process involves staged hydrorefining to remove heteroatoms such as sulfur, nitrogen, oxygen, and chlorine, and hydrogenating aromatics to cycloalkanes. The hydrorefined oil is then subjected to precise vacuum fractionation, and the narrow fraction is dewaxed with urea to produce a series of lubricating oil base oils and specialty industrial waxes. This process improves responsiveness to changes in oil source, expanding the oil source from naphthenic crude oil to intermediate-based crude oil, reducing hydrogen consumption, narrowing the distillation range, increasing added value, and achieving high-value utilization of all components, thus achieving the goal of refining lubricating oil fractions with low energy consumption.

[0005] The technical solution of the present invention:

[0006] A process for the fractional refining and high-value utilization of naphthenic or intermediate-based lubricating oil fractions includes the following steps: First, the naphthenic or intermediate-based lubricating oil fractions are subjected to complexation extraction to remove naphthenic acids at a solvent-to-oil ratio of 0.1-5:1 (mass). The complexation extract is then back-extracted with a low-boiling-point solvent oil to remove neutral oil, yielding naphthenic acid products and deacidified lubricating oil fractions. The complexation deacidification temperature is 15-50℃, and the acid value of the fraction oil is reduced to ≤0.3 mgKOH / g. The complexation deacidifying agent and low-boiling-point solvent oil are recovered and reused through phase-change-free distillation. Second, the deacidified lubricating oil fractions are further refined through staged hydrogenation to remove sulfur, nitrogen, oxygen, heteroatoms, and hydrogenated saturated aromatics, resulting in nitrogen, sulfur, oxygen, and heteroatom content of less than 100%. The first step involves obtaining a high-cycloalkyl hydrogenated distillate oil with an aromatic ring content of less than 1% (PPm). The second step involves precise fractionation of the high-cycloalkyl hydrogenated oil under reduced pressure to obtain a series of narrow-range lubricating oils with a distillation range of less than 45℃. The third step involves urea-based dewaxing of the narrow-range lubricating oils at a solvent-to-oil ratio of 1-10:1. The dewaxed oil is then recycled through phase-change-free distillation to obtain special industrial wax products and low-pour-point lubricating oil base oils. These base oils are used to produce new energy cooling oils, transformer oils, rubber filler oils, low-pour-point greases, or low-pour-point lubricating oils. Phase-change-free distillation involves using pressurized and heated overhead steam to reheat the preheated feedstock. The high-temperature feedstock enters the distillation column and is separated into bottom material and overhead steam. The overhead steam is pressurized and heated by a compressor to reheat the feedstock, resulting in a recycled overhead liquid product. The bottom material is discharged as a product after heat exchange with the feedstock.

[0007] The lubricating oil fraction complexation deacidification technology employs an easily regenerable amine alcohol complexation deacidifying agent and a hydrophilic fiber bundle-filled mixing coalescer. The amine alcohol complexation deacidifying agent is an alcohol-water-amine composite solvent, where the alcohol is one or more of methanol, ethanol, n-propanol, isopropanol, or butanol, and the amine is one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, diisopropylamine, tripropylamine, n-butylamine, sec-butylamine, or tert-butylamine. The mass ratio of alcohol, water, and amine is 2-10:1-5:1. The cycloalkyl or intermediate-based lubricating oil fraction is pre-mixed in a pipeline mixer at an agent-to-oil mass ratio of 0.1-5:1 before entering the mixing coalescer. The amine alcohol complexation deacidification process then proceeds to the mixing coalescer. The acid agent is adsorbed and extended into a film on the surface of the hydrophilic fiber bundle and flows downward. The lubricating oil fraction flows between the fibers of the hydrophilic fiber bundle and forms a non-dispersive contact reaction with the amino alcohol complexing deacidifying agent. Finally, the complexing extract condenses and separates at the lower end of the hydrophilic fiber bundle and enters the aqueous phase. The deacidified lubricating oil fraction flows out from between the middle and lower fibers of the hydrophilic fiber bundle and enters the oil phase. The complexing extract in the aqueous phase is back-extracted with low-boiling-point solvent oil to recover neutral oil. The extract oil and complexing extract are recycled by low-energy recovery of low-boiling-point solvent oil and amino alcohol complexing deacidifying agent through phase change-free distillation, respectively, to obtain high-purity naphthenic acid product and neutral oil. The neutral oil is blended back into the deacidified lubricating oil fraction and enters the next hydrorefining process.

[0008] The lubricating oil fraction complexation and decycloalkanoic acid technology can be of level one, or level two to four.

[0009] The stepwise hydrorefining of deacidified lubricating oil fractions refers to the process where the deacidified lubricating oil fractions first undergo hydrorefining to remove nitrogen, sulfur, oxygen, and heteroatoms, followed by deep hydrogenation of the aromatic rings to saturate and generate cycloalkanes. The hydrogen partial pressure during hydrorefining is 6.0-20.0 MPa, the temperature is 300-400℃, and the volume hourly space velocity is 0.1-1.0 h⁻¹. -1 The partial pressure of hydrogen saturation for aromatic ring hydrogenation is 7.0-30.0 MPa, the temperature is 360-450℃, and the volume hourly space velocity is 0.3-3.0 h⁻¹. -1 Hydrogen-to-oil volume ratio 800-2000 NL / m 3 .

[0010] High-cycloalkyl hydrogenated oil vacuum distillation refers to the process of refining high-cycloalkyl hydrogenated oil into different fractions with different final boiling points through a multi-side-stream vacuum distillation tower. Each fraction then flows into a stripping tower attached to the vacuum distillation tower, where it is clearly cut using special stripping trays to control the initial boiling point to meet product requirements. The stripped vapor phase returns to the upper part of the rectification section corresponding to each side-stream of the vacuum distillation tower and is then further separated by the next rectification section to obtain a series of narrow-range lubricating oil fractions with the required distillation range.

[0011] Narrow-fraction urea-based dewaxing of lubricating oil refers to the process of mixing a narrow-fraction lubricating oil with a low-boiling-point solvent oil at a desired solvent-to-oil ratio, then adding a urea-water-alcohol solution. After thorough mixing at 25-35°C, a complexation and inclusion reaction occurs, forming a stable solid complex. This complex is then separated from the dewaxed oil by sedimentation. The alcohol in the urea-water-alcohol solution is one or more of methanol, ethanol, n-propanol, isopropanol, or butanol, with a mass ratio of 2-5:1:1-10. The separated solid complex is washed again with the low-boiling-point solvent oil and then heated to 70-100°C. The complex decomposes into urea and n-alkanes. The urea can be recycled, while the n-alkanes are used as a special industrial wax. The washing oil and dewaxed oil are mixed and then the low-boiling-point solvent oil is recovered and recycled through phase-change-free distillation. The bottom product is used as a base oil for low-pour-point lubricating oil.

[0012] The features of the present invention will be described in detail through embodiments. Attached Figure Description

[0013] Appendix Figure 1 This is a schematic diagram of the process of the present invention.

[0014] Appendix Figure 1 The diagram is explained as follows:

[0015] 1. Pump 2. Pipeline mixer 3. Complex extraction mixing and coalescing unit 4. Back-extraction mixing and coalescing unit 5. Solvent oil phase change-free distillation column 6. Complex deacidifying agent phase change-free distillation column 7. Hydrogenation refining reactor 8. Hydrogenation saturation reactor 9. Vacuum distillation column 10. Stripping column 11. Urea composite dewaxing reactor A. Lubricating oil fraction B. Complex deacidifying agent C. Naphthenic acid D. Vacuum dry gas E. Special industrial wax F. Lubricating oil base oil

[0016] The process features of the present invention will be described in detail below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0017] Example 1: A process for the high-value utilization of all resources in the fractional refining of cycloalkyl or intermediate-based lubricating oil distillate. Step 1: Cycloalkyl or intermediate-based lubricating oil distillate A is pre-mixed with an amine complexing deacidifying agent B at a mass ratio of 5:1 in a pipeline mixer 2 via pump 1. The mass ratio of isopropanol, water, and diethylamine in the amine complexing deacidifying agent B is 10:5:1. The complexing deacidification temperature is 50°C. The mixture then enters a complexing extraction mixing and coalescing unit 3. The amine complexing deacidifying agent B adsorbs and extends onto the surface of the hydrophilic fiber bundles in the complexing extraction mixing and coalescing unit 3, forming a film that flows downwards. Lubricating oil distillate A flows between the fibers of the hydrophilic fiber bundles and interacts with the amine complexing deacidifying agent B. A non-dispersive contact reaction is formed. Finally, the complexed extract condenses and separates at the lower end of the hydrophilic fiber bundles and enters the aqueous phase. The deacidified lubricating oil fraction flows out from the middle and lower fiber spaces of the hydrophilic fiber bundles and enters the oil phase. The aqueous complexed extract is back-extracted through a low-boiling-point solvent oil in a back-extraction mixing and coalescing unit 4 to recover neutral oil. The extracted oil is then recycled back to the back-extraction feed in a low-energy solvent oil non-phase-change distillation column 5. The complexed extract is then recycled back to the lubricating oil fraction A feed pump 1 after low-energy recovery of the amine alcohol complexing deacidifying agent in a non-phase-change distillation column 6. This process yields high-purity naphthenic acid product C and neutral oil. The neutral oil is blended back into the deacidified lubricating oil fraction and enters the next hydrorefining process. The deacidification rate is ≥99.5%, and the acid value of the fraction oil is reduced to ≤0.01. mgKOH / g, complexing deacidifying agent recovery rate ≥99.5%, saving more than 45% energy compared with traditional solvent deacidification process; high-purity naphthenic acid acid value ≥177 mgKOH / g, which is better than the quality standard of acid No. 55.

[0018] In the second step, the deacidified lubricating oil fraction is first hydrotreated in hydrorefining reactor 7 to remove nitrogen, sulfur, oxygen, and heteroatoms. The hydrogen partial pressure is 6.0 MPa, the temperature is 400℃, and the volume hourly space velocity is 0.1 h⁻¹. The nitrogen, sulfur, oxygen, and heteroatom content of the hydrotreated oil is less than 50 ppm. The hydrotreated oil is then subjected to deep aromatic ring hydrosaturation in hydrosaturation reactor 8 to generate cycloalkanes. The hydrogen partial pressure is 30.0 MPa, the temperature is 360℃, the volume hourly space velocity is 3.0 h⁻¹, and the hydrogen-to-oil volume ratio is 2000 NL / m³. The hydrogen consumption is reduced by 42% compared to the full-fraction hydrotreating technology, and the aromatic ring hydrosaturation rate is over 99.5%, resulting in a high-cycloalkyl hydrotreated distillate oil with an aromatic ring content of less than 1%.

[0019] The third step involves refining the high-cycloalkyl hydrogenated oil into different fractions with final boiling points that meet the requirements using a multi-side-stream vacuum distillation tower 9. Each fraction then flows into a stripping tower 10 attached to the vacuum distillation tower, where it is clearly cut using special stripping trays to control the initial boiling point to meet product requirements. The stripped vapor phase returns to the area above the corresponding rectification section of each side-stream of the vacuum distillation tower 9 and is then further refined in the next rectification section to obtain a narrow fraction of lubricating oil with a distillation range of 27°C.

[0020] In the fourth step, the narrow fraction of lubricating oil and low-boiling-point solvent oil are mixed at a volume ratio of 1:1 and then fed into urea composite dewaxing reactor 1. A urea-water-isopropanol solution with a mass ratio of 2:1:1 is added, and the mixture is stirred and mixed evenly at 25°C. A complexation and containment reaction occurs, forming a stable solid complex, which is separated from the dewaxed oil by sedimentation. The separated solid complex is washed again with low-boiling-point solvent oil and heated to 70°C. The complex decomposes into urea and n-alkanes. The urea can be recycled, and the n-alkanes are used as special industrial wax F. The washing oil and dewaxed oil are mixed and then the low-boiling-point solvent oil is recovered and recycled through phase-change-free distillation. The bottom material is used as low-pour-point lubricating oil base oil E. Low-pour-point lubricating oil base oil E is used to produce new energy cooling oil, transformer oil, rubber filler oil, low-pour-point grease, or low-pour-point lubricating oil.

[0021] Example 2: A process for the high-value utilization of all resources in the fractional refining of cycloalkyl or intermediate-based lubricating oil distillate. Step 1: Cycloalkyl or intermediate-based lubricating oil distillate A is added to pipeline mixer 2 via pump 1 along with an amine complexing deacidifying agent B at a mass ratio of 0.3:1 for initial pre-mixing. The mass ratio of isopropanol, water, and diethylamine in the amine complexing deacidifying agent B is 7:2:1. The complexing deacidification temperature is 30°C. The mixture then enters a complexing extraction mixing and coalescing unit 3. The amine complexing deacidifying agent B adsorbs and extends onto the surface of the hydrophilic fiber bundles in the complexing extraction mixing and coalescing unit 3, forming a film that flows downwards. Lubricating oil distillate A flows between the fibers of the hydrophilic fiber bundles and interacts with the amine complexing deacidifying agent B. A non-dispersive contact reaction is formed. Finally, the complexed extract condenses and separates at the lower end of the hydrophilic fiber bundles and enters the aqueous phase. The deacidified lubricating oil fraction flows out from the middle and lower fiber spaces of the hydrophilic fiber bundles and enters the oil phase. The aqueous complexed extract is back-extracted through a low-boiling-point solvent oil in a back-extraction mixing and coalescing unit 4 to recover neutral oil. The extracted oil is then recycled back to the back-extraction feed in a low-energy solvent oil non-phase-change distillation column 5. The complexed extract is then recycled back to the lubricating oil fraction A feed pump 1 after low-energy recovery of the amine alcohol complexing deacidifying agent in a non-phase-change distillation column 6. This process yields high-purity naphthenic acid product C and neutral oil. The neutral oil is blended back into the deacidified lubricating oil fraction and enters the next hydrorefining process, achieving a deacidification rate ≥99% and reducing the acid value of the fraction oil to ≤0.02. mgKOH / g, complexing deacidifying agent recovery rate ≥99.5%, saving more than 50% energy compared with traditional solvent deacidification process; high-purity naphthenic acid acid value ≥177 mgKOH / g, which is better than the quality standard of acid No. 55.

[0022] In the second step, the deacidified lubricating oil fraction is first hydrotreated in hydrorefining reactor 7 to remove nitrogen, sulfur, oxygen, and heteroatoms. The hydrogen partial pressure is 8.0 MPa, the temperature is 350℃, and the volume hourly space velocity is 0.3 h⁻¹. The nitrogen, sulfur, oxygen, and heteroatom content of the hydrotreated oil is less than 50 ppm. The hydrotreated oil is then deeply hydrotreated in hydrosaturation reactor 8 to generate cycloalkanes through aromatic ring deep hydrosaturation. The hydrogen partial pressure is 20.0 MPa, the temperature is 380℃, the volume hourly space velocity is 1.0 h⁻¹, and the hydrogen-to-oil volume ratio is 1500 NL / m³. The hydrogen consumption is reduced by 40% compared to the full-fraction hydrotreating technology, and the aromatic ring hydrosaturation rate is over 99%, resulting in a high-cycloalkyl hydrotreated distillate oil with an aromatic ring content of less than 1%.

[0023] The third step involves refining the high-cycloalkyl hydrogenated oil into different fractions with final boiling points that meet the requirements using a multi-side-stream vacuum distillation tower 9. Each fraction then flows into a stripping tower 10 attached to the vacuum distillation tower, where it is clearly cut using special stripping trays to control the initial boiling point to meet product requirements. The stripped vapor phase returns to the area above the corresponding rectification section of each side-stream of the vacuum distillation tower 9 and is then further refined in the next rectification section to obtain a narrow fraction of lubricating oil with a distillation range of 28°C.

[0024] In the fourth step, the narrow fraction of lubricating oil and low-boiling-point solvent oil are mixed at a volume ratio of 5:1 and then fed into urea composite dewaxing reactor 1. A urea-water-isopropanol solution with a mass ratio of 2:1:2 is added, and the mixture is stirred and mixed evenly at 30°C. A complexation and containment reaction occurs, forming a stable solid complex, which is separated from the dewaxed oil by sedimentation. The separated solid complex is washed again with low-boiling-point solvent oil and heated to 85°C. The complex decomposes into urea and n-alkanes. The urea can be recycled, and the n-alkanes are used as special industrial wax F. The washing oil and dewaxed oil are mixed and then the low-boiling-point solvent oil is recovered and recycled through phase-change-free distillation. The bottom material is used as low-pour-point lubricating oil base oil E, which is used to produce new energy cooling oil, transformer oil, rubber filler oil, low-pour-point grease, or low-pour-point lubricating oil.

[0025] Example 3: A process for the high-value utilization of all resources in the fractional refining of cycloalkyl or intermediate-based lubricating oil fractions. Step 1: Cycloalkyl or intermediate-based lubricating oil fraction A is added to pipeline mixer 2 via pump 1 along with an amine complexing deacidifying agent B at a mass ratio of 0.1:1 for initial pre-mixing. The mass ratio of isopropanol, water, and diethylamine in the amine complexing deacidifying agent B is 2:1:1. The complexing deacidification temperature is 15°C. The mixture then enters a complexing extraction mixing and coalescing unit 3. The amine complexing deacidifying agent B adsorbs and extends onto the surface of the hydrophilic fiber bundles in the complexing extraction mixing and coalescing unit 3, forming a film that flows downwards. Lubricating oil fraction A flows between the fibers of the hydrophilic fiber bundles and interacts with the amine complexing deacidifying agent B. A non-dispersive contact reaction is formed. Finally, the complexed extract condenses and separates at the lower end of the hydrophilic fiber bundles and enters the aqueous phase. The deacidified lubricating oil fraction flows out from the middle and lower fiber spaces of the hydrophilic fiber bundles and enters the oil phase. The aqueous complexed extract is back-extracted through a low-boiling-point solvent oil in a back-extraction mixing and coalescing unit 4 to recover neutral oil. The extracted oil is then recycled back to the back-extraction feed in a low-energy solvent oil non-phase-change distillation column 5. The complexed extract is then recycled back to the lubricating oil fraction A feed pump 1 after low-energy recovery of the amine alcohol complexing deacidifying agent in a non-phase-change distillation column 6. This process yields high-purity naphthenic acid product C and neutral oil. The neutral oil is blended back into the deacidified lubricating oil fraction and enters the next hydrorefining process, achieving a deacidification rate ≥99% and reducing the acid value of the fraction oil to ≤0.02. mgKOH / g, complexing deacidifying agent recovery rate ≥99.5%, saving more than 70% energy compared with traditional solvent deacidification process; high-purity naphthenic acid acid value ≥170 mgKOH / g, which is better than the quality standard of acid No. 55.

[0026] In the second step, the deacidified lubricating oil fraction is first hydrotreated in hydrorefining reactor 7 to remove nitrogen, sulfur, oxygen, and heteroatoms. The hydrogen partial pressure is 20.0 MPa, the temperature is 300℃, and the volume hourly space velocity is 1.0 h⁻¹. The nitrogen, sulfur, oxygen, and heteroatom content of the hydrotreated oil is less than 35 ppm. The hydrotreated oil is then subjected to deep aromatic ring hydrosaturation in hydrosaturation reactor 8 to generate cycloalkanes. The hydrogen partial pressure is 7.0 MPa, the temperature is 450℃, the volume hourly space velocity is 0.1 h⁻¹, and the hydrogen-to-oil volume ratio is 800 NL / m³. The hydrogen consumption is reduced by 39% compared to the full-fraction hydrotreating technology, and the aromatic ring hydrosaturation rate is 99%, resulting in a high-cycloalkyl hydrotreated distillate oil with an aromatic ring content of less than 1%.

[0027] The third step involves refining the high-cycloalkyl hydrogenated oil into different fractions with final boiling points that meet the requirements using a multi-side-stream vacuum distillation tower 9. Each fraction then flows into a stripping tower 10 attached to the vacuum distillation tower, where it is clearly cut using special stripping trays to control the initial boiling point to meet product requirements. The stripped vapor phase returns to the area above the corresponding rectification section of each side-stream of the vacuum distillation tower 9 and is then further refined in the next rectification section to obtain a narrow fraction of lubricating oil with a distillation range of 28°C.

[0028] In the fourth step, the narrow fraction of lubricating oil and low-boiling-point solvent oil are mixed at a volume ratio of 10:1 and then fed into urea composite dewaxing reactor 1. A urea-water-isopropanol solution with a mass ratio of 5:1:10 is added, and the mixture is stirred and mixed evenly at 35°C. A complexation and containment reaction occurs, forming a stable solid complex, which is separated from the dewaxed oil by sedimentation. The separated solid complex is washed again with low-boiling-point solvent oil and heated to 100°C. The complex decomposes into urea and n-alkanes. The urea can be recycled, and the n-alkanes are used as special industrial wax F. The washing oil and dewaxed oil are mixed and then the low-boiling-point solvent oil is recovered and recycled through phase-change-free distillation. The bottom material is used as low-pour-point lubricating oil base oil E. Low-pour-point lubricating oil base oil E is used to produce new energy cooling oil, transformer oil, rubber filling oil, low-pour-point grease, or low-pour-point lubricating oil.

[0029] The present invention provides a process for the fractional refining and high-value utilization of naphthenic or intermediate-based lubricating oil fractions. This process expands the oil source from naphthenic crude oil to intermediate-based crude oil, which accounts for more than 50%, increasing the source of feedstock by more than 20 times. The utilization rate of lubricating oil fractions is increased from ≤50% to full-component high-value utilization. The distillation range is narrowed from the current ≥55℃ to ≤30℃, and the added value is increased by ≥30%. This maximizes the low-cost and controllable production of high-grade low-pour-point base oils, specialty waxes, and high-purity naphthenic acid products of different grades.

Claims

1. A process for the fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillates, characterized in that the first step: The first step involves complexing and extracting naphthenic acids from the alkyl or intermediate-based lubricating oil fraction at a solvent-to-oil mass ratio of 0.1-5:

1. The complexing extract is then back-extracted with a low-boiling-point solvent to remove neutral oil, yielding the naphthenic acid product and the deacidified lubricating oil fraction. The complexing and deacidification temperature is 15-50℃, and the acid value of the fractional oil is reduced to ≤0.3 mgKOH / g. The complexing and deacidifying agent and the low-boiling-point solvent oil are recovered and reused through phase-change-free distillation. The second step involves staged hydrogenation refining of the deacidified lubricating oil fraction to remove nitrogen, oxygen, heteroatoms, and hydrogenated saturated aromatics. The nitrogen, sulfur, oxygen, and heteroatom content is less than 100 ppm, and the aromatic ring content is less than 1%, yielding a high-cycloalkyl hydrogenated fraction oil. The third step involves precise fractionation of the high-cycloalkyl hydrogenated oil under reduced pressure to obtain a series of narrow-range lubricating oil fractions with a distillation range of less than 45℃. Step 4: Dewaxing the narrow fraction of lubricating oil with urea at a solvent-to-oil ratio of 1-10:

1. The dewaxed oil is then recycled through phase-change-free distillation to obtain special industrial wax products and low-pour-point lubricating oil base oil. The low-pour-point lubricating oil base oil is used to produce new energy cooling oil, transformer oil, rubber filler oil, low-pour-point grease, or low-pour-point lubricating oil. Phase-change-free distillation involves using pressurized and heated overhead steam to reheat the preheated feedstock, which has already been heated by the bottom material. After entering the distillation column, the high-temperature feedstock is separated into bottom material and overhead steam. The overhead steam is pressurized and heated by a compressor to reheat the feedstock, resulting in the overhead liquid product, which is recycled. The bottom material is discharged as a product after exchanging heat with the feedstock.

2. The process for fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillate according to claim 1, characterized in that... The lubricating oil fraction complexation deacidification technology employs an easily regenerable amine alcohol complexation deacidifying agent and a mixing coalescer filled with hydrophilic fiber bundles. The amine alcohol complexation deacidifying agent is an alcohol-water-amine composite solvent. The alcohol is one or more mixtures of methanol, ethanol, n-propanol, isopropanol, or butanol, and the amine is one or more mixtures of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, diisopropylamine, tripropylamine, n-butylamine, sec-butylamine, or tert-butylamine. The mass ratio of alcohol, water, and amine is 2-10:1-5:

1. The cycloalkyl or intermediate-based lubricating oil fraction is initially premixed in a pipeline mixer at an agent-to-oil mass ratio of 0.1-5:1 before entering the mixing coalescer. The lubricating oil fraction adsorbs and extends to form a film on the surface of the hydrophilic fiber bundle and flows downward. The lubricating oil fraction flows between the fibers of the hydrophilic fiber bundle and forms a non-dispersive contact reaction with the amino alcohol complexing deacidifying agent. Finally, the complexing extract condenses and separates at the lower end of the hydrophilic fiber bundle and enters the aqueous phase. The deacidified lubricating oil fraction flows out from between the middle and lower fibers of the hydrophilic fiber bundle and enters the oil phase. The complexing extract in the aqueous phase is back-extracted with low-boiling-point solvent oil to recover neutral oil. The extract oil and complexing extract are recycled by low-energy recovery of low-boiling-point solvent oil and amino alcohol complexing deacidifying agent through phase change-free distillation, respectively, to obtain high-purity naphthenic acid product and neutral oil. The neutral oil is blended back into the deacidified lubricating oil fraction and enters the next hydrorefining process.

3. The process for fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillate according to claim 1, characterized in that... The lubricating oil fraction complexation and decycloalkanoic acid technology is one of the first, second, third, and fourth stages.

4. The process for fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillate according to claim 1, characterized in that... The stepwise hydrorefining of deacidified lubricating oil fractions refers to the process where the deacidified lubricating oil fractions first undergo hydrorefining to remove nitrogen, sulfur, oxygen, and heteroatoms, followed by deep hydrogenation of the aromatic rings to saturate and generate cycloalkanes. The hydrogen partial pressure during hydrorefining is 6.0-20.0 MPa, the temperature is 300-400℃, and the volume hourly space velocity is 0.1-1.0 h⁻¹. -1 The partial pressure of hydrogen saturation for aromatic ring hydrogenation is 7.0-30.0 MPa, the temperature is 360-450℃, and the volume hourly space velocity is 0.3-3.0 h⁻¹. -1 Hydrogen-to-oil volume ratio 800-2000 NL / m 3 .

5. The process for fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillate according to claim 1, characterized in that... High-cycloalkyl hydrogenated oil vacuum distillation refers to the process of refining high-cycloalkyl hydrogenated oil into different fractions with different final boiling points through a multi-side-stream vacuum distillation tower. Each fraction then flows into a stripping tower attached to the vacuum distillation tower, where the stripping plates clearly cut the oil to control the initial boiling point to meet product requirements. The stripped vapor phase returns to the upper part of the rectification section corresponding to each side-stream of the vacuum distillation tower and is then further refined and separated in the next rectification section to obtain a series of narrow-range lubricating oil fractions with the required distillation range.

6. The process for fractional refining and high-value utilization of cycloalkyl or intermediate-based lubricating oil distillate according to claim 1, characterized in that... Narrow-fraction urea-based dewaxing of lubricating oil refers to the process of mixing a narrow-fraction lubricating oil with a low-boiling-point solvent oil at a desired solvent-to-oil ratio, then adding a urea-water-alcohol solution. After thorough mixing at 25-35°C, a complexation and inclusion reaction occurs, forming a stable solid complex. This complex is then separated from the dewaxed oil by sedimentation. The alcohol in the urea-water-alcohol solution is one or more of methanol, ethanol, n-propanol, isopropanol, or butanol, with a mass ratio of 2-5:1:1-10. The separated solid complex is washed again with the low-boiling-point solvent oil and then heated to 70-100°C. The complex decomposes into urea and n-alkanes. The urea can be recycled, while the n-alkanes are used as a special industrial wax. The washing oil and dewaxed oil are mixed and then the low-boiling-point solvent oil is recovered and recycled through phase-change-free distillation. The bottom product is used as a base oil for low-pour-point lubricating oil.

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