Process for the solvent separation and recovery of a vinyl lubricating oil base

Abstract

The application discloses a solvent separation and recovery process of a vinyl lubricating oil base oil, and comprises the following steps: step S1, obtaining organic solvent vapor and crude oil by removing the reaction liquid from a dissolving unit; step S2, obtaining refined solvent by refining the organic solvent vapor in a solvent rectification unit; step S3, obtaining tail gas condensate and tail gas non-condensable gas by condensing tail gas containing solvent vapor in a tail gas condensation recovery unit; and step S4, passing the tail gas non-condensable gas through a tail gas adsorption unit. The application mainly solves the problems of poor separation effect of reaction products, low product quality and inability to reach an industrial scale in the prior art.

Description

Technical Field

[0001] This invention relates to the field of vinyl lubricating oil base oil technology, and more particularly to a solvent separation and recovery process for vinyl lubricating oil base oil. Background Technology

[0002] Industrially, base oils for lubricating oils are obtained through petroleum cracking or α-olefin oligomerization. For example, invention patent CN202010768868.1 discloses a system and method for preparing high-grade lubricating oil mPAO, specifically disclosing a method for preparing high-grade lubricating oil mPAO products using α-olefins as raw materials. However, the technology for selectively producing α-olefins with C6 or more is currently immature, resulting in high prices.

[0003] A novel technical solution provided by researchers in this field allows for the direct preparation of high-performance base oils from inexpensive olefins such as ethylene, propylene, and butene, significantly reducing preparation costs. For example:

[0004] Invention patent CN201410555078.X discloses a novel type of polyolefin catalyst and its preparation technology. Specifically, it discloses a catalytic system comprising a novel type of iron, cobalt, nickel, palladium, and platinum complex. By regulating the catalyst structure, under the action of this type of catalyst, oily, highly branched polymers can be directly prepared from simple olefins such as ethylene, propylene, and butene, as well as polar olefins containing functional groups. However, this invention patent only relates to the preparation of hydrogenated oily alkane mixtures and does not cover subsequent refining processes or tail gas recovery processes.

[0005] Invention patent CN201911032664.5 discloses a process for directly synthesizing high-performance, low-viscosity base oils from low-carbon olefins via polymerization, and another process for directly synthesizing high-performance, low-viscosity base oils from low-carbon olefins via polymerization. The method includes multiple steps such as polymerization, hydrogenation, and distillation. Different basic physicochemical properties of lubricating oil base oils are prepared by varying the amount of catalyst added, solvent volume, and reaction conditions. Furthermore, invention patents by the same applicant CN201911032648.6 disclose a process for directly synthesizing high-performance, medium-viscosity base oils from low-carbon olefins via polymerization, and invention patent CN201911032604.3 discloses a process for directly synthesizing high-performance, high-viscosity base oils from low-carbon olefins via polymerization.

[0006] However, the invention patents CN201911032664.5, CN201911032648.6, and CN201911032604.3 are merely methods for intermittently preparing lubricating oil base oil on a laboratory scale, and do not involve solvent recovery or waste gas treatment. Summary of the Invention

[0007] To achieve the above objectives, this invention provides a solvent separation and recovery process for vinyl lubricating oil base oil, which mainly solves the problems of poor separation effect of reaction products, low product quality, and inability to achieve industrial scale in the existing technology.

[0008] A solvent separation and recovery process for vinyl lubricating oil base oil includes the following steps:

[0009] Step S1: The reaction solution is passed through a solvent removal unit to obtain organic solvent vapor and crude oil.

[0010] The reaction liquid and / or tail gas condensate enter the rising film evaporator for heating, and then enter the steam separator to separate organic solvent vapor and crude oil.

[0011] Step S2: Organic solvent vapor is distilled through a solvent distillation unit to obtain the distilled solvent.

[0012] The organic solvent vapor enters the distillation column for distillation. The bottom liquid of the column is cooled by the bottom cooler of the distillation column and then pumped to the solvent storage tank after distillation by the bottom liquid pump.

[0013] Step S3: The tail gas containing solvent vapor is processed by a tail gas condensation and recovery unit to obtain tail gas condensate and tail gas non-condensable gas.

[0014] The tail gas containing solvent vapor is condensed sequentially by a primary tail gas condenser and a secondary tail gas condenser, and the condensed tail gas condensate is collected in a first condensate receiving tank and a second condensate receiving tank, respectively.

[0015] Step S4: The non-condensable exhaust gas passes through the exhaust gas adsorption unit:

[0016] The non-condensable exhaust gas enters the exhaust gas adsorption tower. The very small amount of solvent that is not condensed is adsorbed and then discharged into the atmosphere in accordance with emission standards.

[0017] Preferably, in step S1, a portion of the crude oil is pumped into a rising film evaporator via an evaporator circulation pump to mix with the reaction liquid for evaporation and desolvation, while the other portion enters a stripping tower. Nitrogen gas is introduced into the bottom of the stripping tower, and a vacuum is drawn at the top of the stripping tower to deeply remove trace amounts of organic solvents from the crude oil. The gas at the top of the stripping tower is cooled by a cooler and then sent to a trace organic solvent storage tank.

[0018] Preferably, in step S2, the operating temperature of the distillation column is -10 to 120°C, and the pressure is ATM to 0.35 MPaG.

[0019] Preferably, in step S2, the overhead gas of the distillation column is refluxed back to the distillation column after passing through the overhead cooler and the overhead storage tank.

[0020] Preferably, in step S2, the organic solvent vapor is fed from the bottom of the distillation column.

[0021] Preferably, the non-condensable gas at the top of the distillation column directly enters the tail gas incineration system.

[0022] Preferably, in step S2, the bottom liquid of the distillation column is cooled to 10-40°C by the bottom cooler of the distillation column.

[0023] Preferably, in step S3, the tail gas containing solvent vapor includes one or more of the following: main catalyst preparation tail gas, co-catalyst preparation tail gas, dichloromethane temporary storage tail gas, polymerization reaction tail gas, quenching unit tail gas, and stripping tail gas.

[0024] Preferably, in step S3, the coolant in the primary exhaust gas condenser is a coolant at -30°C.

[0025] Preferably, in step S3, the coolant in the secondary exhaust gas condenser is the circulating working fluid from the TCU cryogenic refrigeration system.

[0026] Preferably, in step S3, the operating temperature of the first-stage tail gas condenser is -20 to 30°C, the operating temperature of the second-stage tail gas condenser is -90 to -20°C, and the operating pressure is -0.05 to 0.1 MPaG.

[0027] The present invention adopts the above technical solution and has the following technical effects compared with the prior art:

[0028] (1) This invention provides a solvent separation and recovery method for vinyl lubricating oil base oil, which greatly improves the solvent recovery rate and solves the problem of generating harmful substances such as dioxins and phosgene after direct combustion of traditional halogen-containing materials, thereby realizing the continuous separation and recovery of halogen-containing organic solvents in vinyl lubricating oil base oil.

[0029] (2) The process provided by the present invention is a continuous industrial separation and recycling process that can achieve stable and convenient production operation on an industrial scale.

[0030] (3) This invention addresses the solvent properties and product characteristics of vinyl lubricating oil base oil by employing a combination system of molecular distillation, rectification, and cold coupling, utilizing condensation and adsorption separation. By adjusting various parameters, a high solvent recovery rate is achieved.

[0031] (4) The present invention can achieve stable production operation at an industrial production scale of 1,000-100,000 tons / year. Attached Figure Description

[0032] Figure 1 This is a flowchart of a solvent separation and recovery method for vinyl lubricating oil base oil according to the present invention;

[0033] The markings in the diagram indicate the following:

[0034] 10-Desolventizing unit, 11-Lifting film evaporator, 12-Steam separator, 13-Evaporator circulation pump, 14-Stripping tower, 15-Cooler, 16-Trace organic solvent storage tank

[0035] 20 - Solvent distillation form; 21 - Distillation column; 22 - Distillation column bottom cooler; 23 - Distillation column bottom liquid pump; 24 - Solvent storage tank after distillation; 25 - Distillation column top cooler; 26 - Top liquid storage tank.

[0036] 30 - Exhaust gas condensation and recovery unit; 31 - First-stage exhaust gas condenser; 32 - Second-stage exhaust gas condenser; 33 - First condensate receiving tank; 34 - Second condensate receiving tank; 35 - TCU cryogenic refrigeration system.

[0037] 40 - Tail gas adsorption unit, 41 - Tail gas adsorption tower. Detailed Implementation

[0038] This invention relates to a process for separating and recovering halogenated organic solvents in the preparation of vinyl lubricating oil base oils. The technical problems it solves are: 1. to achieve continuous industrial recovery of halogenated organic solvents; 2. to solve the problem of generating harmful substances such as dioxins and phosgene after the direct combustion of tail gas containing halogenated organic solvents in the prior art.

[0039] To address the above problems, this invention provides a solvent separation and recovery process for vinyl lubricating oil base oils, such as... Figure 1 Specifically, it includes the following steps:

[0040] Step S1: The reaction solution is passed through the desolventizing unit 10 to obtain organic solvent vapor and crude oil.

[0041] Specifically, the reaction liquid from the reactor and / or the tail gas condensate from the tail gas condensation and recovery unit 30 enter the rising film evaporator 11 for heating, and then enter the steam separator 12 to separate organic solvent vapor and crude oil.

[0042] In one embodiment, crude oil is pumped by evaporator circulation pump 13 to rising film evaporator 11 to mix with reaction liquid and tail gas condensate for evaporation and desolvation.

[0043] In another embodiment, crude oil enters stripping tower 14, where nitrogen gas is introduced into the bottom of stripping tower 14, and the top of stripping tower 14 is evacuated to deeply remove trace amounts of organic solvents from the crude oil. The gas from the top of stripping tower 14 is cooled by cooler 15 and then sent to trace organic solvent storage tank 16.

[0044] In a preferred embodiment, a portion of the crude oil is pumped by the evaporator circulation pump 13 to the rising film evaporator 11 to mix with the reaction liquid and tail gas condensate for evaporation and desolvation; another portion enters the stripping tower 14, wherein nitrogen gas is introduced into the bottom of the stripping tower 14, and the top of the stripping tower 14 is evacuated to deeply remove trace amounts of organic solvents from the crude oil. The top gas of the stripping tower 14 is cooled by the cooler 15 and then sent to the trace organic solvent storage tank 16.

[0045] Step S2: Organic solvent vapor is passed through solvent distillation unit 20 to obtain distilled solvent;

[0046] Specifically, the organic solvent vapor enters the distillation column 21 from the bottom for distillation. The bottom liquid is cooled by the bottom cooler 22 and then pumped to the distillation solvent storage tank 24 by the bottom liquid pump 23. The top gas of the distillation column 21 is returned to the distillation column 21 after passing through the top cooler 25 and the top liquid storage tank 26. The non-condensable gas at the top of the distillation column 21 directly enters the tail gas incineration system.

[0047] In a preferred embodiment, the operating temperature of the distillation column 21 is -10 to 120°C, and the pressure is ATM to 0.35 MPaG.

[0048] In a preferred embodiment, in step S2, the bottom liquid of the distillation column 21 is cooled to 10-40°C by the bottom cooler of the distillation column; further, it is cooled to 20°C.

[0049] Step S3: The tail gas containing solvent vapor is processed by the tail gas condensation and recovery unit 30 to obtain the tail gas condensate and tail gas non-condensable gas.

[0050] Specifically, the tail gas containing solvent vapor is condensed sequentially by a primary tail gas condenser 31 and a secondary tail gas condenser 32, and the condensed tail gas condensate is collected in a first condensate receiving tank 33 and a second condensate receiving tank 34, respectively. In particular, the tail gas containing solvent vapor includes one or more of the following: main catalyst preparation tail gas, co-catalyst preparation tail gas, dichloromethane temporary storage tail gas, polymerization reaction tail gas, quenching unit tail gas, and gas stripping tail gas.

[0051] In one embodiment, in step S3, the coolant in the primary exhaust gas condenser 31 is a coolant at -30°C.

[0052] In a preferred embodiment, in step S3, the coolant of the secondary exhaust gas condenser 32 is the circulating working fluid from the TCU cryogenic refrigeration system 35.

[0053] Step S4: The non-condensable exhaust gas passes through the exhaust gas adsorption unit 40;

[0054] The non-condensable exhaust gas enters the exhaust gas adsorption tower 41. The very small amount of solvent that is not condensed is adsorbed and then discharged into the atmosphere in accordance with the emission standards.

[0055] In a preferred embodiment, the cooling medium of the secondary tail gas condenser can be existing materials in the plant such as cryogenic ethylene, liquid nitrogen, or liquid ammonia. This achieves the vaporization of the cryogenic medium while recovering the solvent, thus completing the coupling of cooling capacity.

[0056] The present invention will now be described in detail and specifically through specific embodiments to enable a better understanding of the invention. However, the following embodiments do not limit the scope of the invention.

[0057] Example 1

[0058] Step S1: The reaction solution is passed through the solvent removal unit 10 to obtain organic solvent vapor and crude oil.

[0059] The reaction solution (mass fraction CH2Cl2 82wt%; LPE-4 4.3wt%; LPE-40 13wt%; other light hydrocarbons 0.7%) quantitatively enters the rising film evaporator 11 to be heated to 100℃, and then enters the steam separator 12. The separated organic solvent vapor enters the solvent distillation unit 20. After preliminary desolventizing, part of the crude oil continues to enter the rising film evaporator 11 through the evaporator circulation pump 13 to mix with the reaction solution for evaporation and desolventizing, and the other part enters the stripping tower 14. Nitrogen gas is introduced into the bottom of the tower and a vacuum is drawn at the top of the tower to deeply remove trace amounts of dichloromethane solvent from the oil. The top gas of the stripping tower 14 is cooled by the cooler 15 and then sent to the trace organic solvent storage tank 16.

[0060] Step S2: Organic solvent vapor is passed through solvent distillation unit 20 to obtain distilled solvent.

[0061] Dichloromethane vapor (CH2Cl2 98.7wt%; other light hydrocarbons 1.3wt%) from the desolventizing process 10 is directly fed into the distillation column 21 for distillation. Bottom feed is used, and the non-condensable gas at the top of the column is directly fed into the tail gas combustion system. The bottom liquid is cooled to 25°C by the bottom cooler 22 of the distillation column, and then pumped to the dichloromethane storage tank 24 after distillation by the bottom liquid pump 23. The operating temperature of this process system is -10 to 120°C, and the pressure is ATM-0.35 MPaG.

[0062] Step S3: The tail gas containing solvent vapor is processed by the tail gas condensation and recovery unit 30 to obtain the tail gas condensate and tail gas non-condensable gas.

[0063] The tail gas containing dichloromethane vapor (including tail gas from the main catalyst preparation, co-catalyst preparation, temporary dichloromethane storage, polymerization reaction, quenching unit, stripping, and supplementary dichloromethane) is combined and sequentially enters the primary tail gas condenser 31 and the secondary tail gas condenser 32. The condensed dichloromethane is collected in the first condensate receiving tank 33 and the second condensate receiving tank 34, respectively. The tail gas condensate and the reaction liquid are combined and enter the rising film evaporator 11. The coolant in the primary tail gas condenser 31 is a coolant at -30°C; the coolant in the secondary tail gas condenser 32 is the circulating working fluid from the TCU cryogenic refrigeration system 35. The operating temperature of the primary tail gas condenser is -20 to 30°C, and the operating temperature of the secondary tail gas condenser is -90 to -20°C, with a pressure of -0.05 to 0.1 MPaG.

[0064] Step S4: The non-condensable exhaust gas passes through the exhaust gas adsorption unit 40;

[0065] The tail gas containing solvent vapor is condensed sequentially by the first-stage tail gas condenser 31 and the second-stage tail gas condenser 32, and the resulting non-condensable tail gas enters the tail gas adsorption tower 41. The very small amount of uncondensed dichloromethane is adsorbed and then discharged into the atmosphere in accordance with emission standards.

[0066] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A solvent separation and recovery process for vinyl lubricating oil base oil, characterized in that, Includes the following steps: Step S1: The reaction solution is passed through a solvent removal unit to obtain organic solvent vapor and crude oil. The reaction liquid from the vinyl lubricating oil base oil reactor and the tail gas condensate from the tail gas condensation recovery unit enter the rising film evaporator for heating, and then enter the steam separator to separate organic solvent vapor and crude oil. A portion of the crude oil is pumped into a rising film evaporator via an evaporator circulation pump to mix with the reaction liquid and circulate for evaporation and desolventization. Another portion enters a stripping tower, where nitrogen gas is introduced into the bottom of the stripping tower and a vacuum is drawn at the top of the stripping tower to deeply remove trace amounts of organic solvents from the crude oil. The gas at the top of the stripping tower is cooled by a cooler and then sent to a trace organic solvent storage tank. Step S2: Organic solvent vapor is distilled through a solvent distillation unit to obtain the distilled solvent. The organic solvent vapor enters the distillation column for distillation. The bottom liquid of the column is cooled by the bottom cooler of the distillation column and then pumped to the solvent storage tank after distillation by the bottom liquid pump. Step S3: The tail gas containing solvent vapor is processed by a tail gas condensation and recovery unit to obtain tail gas condensate and tail gas non-condensable gas. The tail gas condensation and recovery unit includes a primary tail gas condenser and a secondary tail gas condenser. The tail gas containing solvent vapor is condensed sequentially by the primary tail gas condenser and the secondary tail gas condenser. The condensed tail gas condensate is collected in the first condensate receiving tank and the second condensate receiving tank, respectively. The coolant of the secondary tail gas condenser is the circulating working fluid from the TCU cryogenic refrigeration system. Step S4: The non-condensable exhaust gas passes through the exhaust gas adsorption unit: The non-condensable exhaust gas enters the exhaust gas adsorption tower. The very small amount of solvent that is not condensed is adsorbed and then discharged into the atmosphere in accordance with emission standards.

2. The solvent separation and recovery process for vinyl lubricating oil base oil according to claim 1, characterized in that, In step S2, the operating temperature of the distillation column is -10~120℃, and the pressure is ATM~0.35MpaG.

3. The solvent separation and recovery process for vinyl lubricating oil base oil according to claim 1, characterized in that, In step S2, the overhead gas of the distillation column is returned to the distillation column after passing through the overhead cooler and the overhead storage tank.

4. In the solvent separation and recovery process of vinyl lubricating oil base oil according to claim 1, in step S2, the organic solvent vapor is fed from the bottom of the distillation column.

5. In the solvent separation and recovery process of vinyl lubricating oil base oil according to claim 1, in step S2, the bottom liquid of the distillation column is cooled to 10~40°C by the bottom cooler of the distillation column.

6. In the solvent separation and recovery process of vinyl lubricating oil base oil according to claim 1, in step S3, the tail gas containing solvent vapor includes one or more of the following: main catalyst preparation tail gas, co-catalyst preparation tail gas, dichloromethane temporary storage tail gas, polymerization reaction tail gas, quenching unit tail gas, and gas stripping tail gas.

7. In the solvent separation and recovery process of vinyl lubricating oil base oil according to claim 1, in step S3, the coolant of the first-stage tail gas condenser is a coolant at -30°C.

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