CN115491226B - Method for recovering dewaxing solvent in heavy lubricating oil base oil filtrate - Google Patents
Method for recovering dewaxing solvent in heavy lubricating oil base oil filtrate Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G31/00—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for
- C10G31/11—Refining of hydrocarbon oils, in the absence of hydrogen, by methods not otherwise provided for by dialysis
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/10—Feedstock materials
- C10G2300/1037—Hydrocarbon fractions
- C10G2300/1062—Lubricating oils
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/20—Characteristics of the feedstock or the products
- C10G2300/201—Impurities
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/40—Characteristics of the process deviating from typical ways of processing
- C10G2300/44—Solvents
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
- C10G2400/10—Lubricating oil
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
- C10G2400/18—Solvents
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Abstract
The invention relates to the field of recycling dewaxing solvent in heavy lubricant base oil filtrate, and discloses a method for recycling dewaxing solvent in heavy lubricant base oil filtrate, which comprises the following steps: (1) Under high pressure condition, the organic solvent nanofiltration membrane is contacted with an organic solvent for pretreatment until the flux of the nanofiltration membrane is stable; the high pressure is 2-8MPa, and the low operation circulation flow is 1-15m 3 /h; (2) And (3) evacuating the organic solvent, and contacting the heavy lubricating oil base oil filtrate with the nanofiltration membrane obtained in the step (1) at a low operation circulation flow rate until the heavy lubricating oil base oil filtrate is operated again stably and the starting is successful. The method effectively shortens the driving time.
Description
Technical Field
The invention relates to the technical field of recycling dewaxing solvents in heavy lubricating oil base oil filtrate, in particular to a method for recycling dewaxing solvents in heavy lubricating oil base oil filtrate.
Background
Lubricating oils are the most widely used and consumer-nearest products in petrochemicals, are important materials related to national life and national security, and are called "blood" in the modern industry. Meanwhile, the lubricating oil is a product with high technical content and high benefit. From the analysis of the overall oil refining industry, the benefit of producing lubricating oil is obviously higher than that of fuel oil. In the production process of lubricating oil, long-chain normal paraffins, namely 'wax', are contained in petroleum fractions, and when the temperature is reduced, the 'wax' can be wrapped around surrounding lubricating oil components to be separated out, so that a network structure is formed, and the flowability of the lubricating oil is affected. Dewaxing is thus an essential step in the lubricant oil production process.
There are generally two processes for dewaxing lubricating oils in commercial processes, solvent dewaxing and hydrodewaxing, respectively. Solvent dewaxing is the earliest method used in lubricant oil production and is the most widely used method today. More than half of the dewaxing processes in the current commercial lubricating oils employ solvent dewaxing processes. The development of a combined solvent dewaxing and hydrogenation process has further extended the life of the solvent dewaxing process.
However, solvent dewaxing has its own drawbacks, such as the large amount of phase change heat required in solvent recovery to complete the solvent recovery, both consuming energy and increasing VOC emissions, which creates significant environmental pressures. Along with the increasing attention of people to health and safety, the energy and environmental protection pressure brought by a large amount of solvent recovery enter the line of sight of people, and a new method capable of reducing energy consumption and environmental pollution is needed to solve the problem of solvent recovery.
The method for recovering dewaxing solvent by membrane separation is the first device named MAX-DEWAX for recovering ketone benzene solvent by membrane separation method in Bowman's oil refinery in 1998. However, their study was limited to the pilot test, and no industrial application other than MAX-DEWAX was reported.
In fact, the start-up of an industrial-size OSN membrane lube dewaxing solvent recovery unit is a difficult task, and the ordinary direct start-up method consumes a long time, so that the rejection rate of the membrane is difficult to increase, and the availability of the OSN membrane in recovering lube dewaxing solvent is easily suspected.
Therefore, a process for recovering dewaxing solvent from heavy lubricant base stock filtrate using OSN is of great importance.
Disclosure of Invention
The invention aims at solving the problems that the novel technology for recovering the dewaxing solvent of the lubricating oil by separating an industrial-grade OSN film has long start time and the rejection rate of the film is difficult to increase.
To achieve the above object, the present invention provides in a first aspect a process for recovering dewaxing solvent from a heavy lubricant base oil filtrate, wherein the process comprises:
(1) Under high pressure condition, the organic solvent nanofiltration membrane is contacted with an organic solvent for pretreatment until the flux of the nanofiltration membrane is stable; wherein the high pressure is 2-8MPa, and the low operation circulation flow is 1-15m 3 /h；
(2) And (3) evacuating the organic solvent, and contacting the heavy lubricating oil base oil filtrate with the nanofiltration membrane obtained in the step (1) at a low operation circulation flow rate until the heavy lubricating oil base oil filtrate is operated again stably and the starting is successful.
Through the technical scheme, the starting time can be shortened by more than 40% by the starting method of the membrane separation device, the membrane separation device can enter a stable operation stage relatively quickly, and the purity of the recovered solvent meets the industrial requirement.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The invention provides a method for recycling dewaxing solvent in heavy lubricating oil base oil filtrate, which is characterized by comprising the following steps:
(1) Under high pressure condition, the organic solvent nanofiltration membrane is contacted with an organic solvent for pretreatment until the flux of the nanofiltration membrane is stable; wherein the high pressure is 2-8MPa, and the low operation circulation flow is 1-15m 3 /h；
(2) And (3) evacuating the organic solvent, and contacting the heavy lubricating oil base oil filtrate with the nanofiltration membrane obtained in the step (1) at a low operation circulation flow rate until the heavy lubricating oil base oil filtrate is operated again stably and the starting is successful.
The inventors of the present invention found that: in the industrial test of recovering lubricating oil dewaxing solvent by membrane separation, the solvent oil content recovered by the pressure of normal operation of membrane separation is always high, the trend of reduction is that the system is under high pressure by adjusting the frequency of a material conveying pump, and meanwhile, the circulating flow is maintained under low operation circulating flow by adjusting the frequency of a circulating pump, so that the solvent oil content recovered by a membrane separation device is greatly reduced in about 5 days, and the requirement of recycling is met. Because the supporting layer of the membrane is compressed during high-pressure operation, the functional layer of the membrane can reach a stable state as soon as possible when enough supporting force is provided, and further, the driving time can be shortened.
According to the present invention, even at the above-defined high pressure and low running circulation flow rate, the start-up time can be shortened, but in the present invention, the high pressure is preferably 3 to 7MPa, more preferably 4 to 6MPa; the low operation circulation flow is 5-12m 3 Preferably 7-10m 3 And/h. In the present invention, the driving time can be further shortened under the preferable condition.
According to the invention, the pretreatment time is from 0.5 to 10 days, preferably from 1 to 5 days, more preferably from 1.5 to 2 days. In the present invention, it is considered that the flux of the nanofiltration membrane after the pretreatment in the step (1) is reduced by less than 1% within 24 hours, and the flux is stable. In addition, preferably, the permeation flux of the nanofiltration membrane is stabilized at 300-500L/branch/h.
According to the invention, the time for the re-stabilization is 3 to 30 days, preferably 4 to 20 days, more preferably 5 to 15 days. In addition, in the invention, in the step (2), after the heavy lubricant base oil filtrate is contacted with the nanofiltration membrane after the step (1) at a low operation circulation flow rate, the flux of the nanofiltration membrane is reduced by less than 1% within 24 hours, and at the moment, the content of the permeate liquid test lubricant is 0.1% -2%, so that the heavy lubricant base oil filtrate can be regarded as the re-stable operation.
According to the invention, preferably, in step (2), two conditions are simultaneously satisfied, namely, the flux of the nanofiltration membrane and the content of lubricating oil in the permeate are simultaneously limited, and the system satisfies the two conditions, which means that the start-up is successful and the stable production state can be entered. Preferably, the flux of the nanofiltration membrane is 300-500L/branch/h, and the content of lubricating oil in the permeate is 0.1% -2%.
According to the invention, the process is carried out at a temperature of from 10 to 50 ℃, preferably from 20 to 40 ℃, more preferably from 25 to 35 ℃.
According to the invention, in the step (1), the permeation flux of the organic solvent nanofiltration membrane after being stabilized is 300-550L/branch/h, preferably 320-500L/branch/h, and in the invention, the permeation flux of the organic solvent nanofiltration membrane is reduced by less than 1% within 24h as a standard for stabilizing the operation flux of the membrane.
According to the invention, the organic solvent nanofiltration membrane (OSN) is one or more selected from a hollow fiber membrane module, a roll membrane module, a tubular membrane module and a plate membrane module, preferably a roll membrane module, and in the invention, the OSN membrane is of an asymmetric structure, is made of a glassy polymer, preferably a polyimide polymer, and most preferably is a P84 polyimide asymmetric nanofiltration membrane.
According to the invention, the molecular weight cut-off of the nanofiltration membrane of the organic solvent is 280-400Da, preferably 300-380Da; preferably, the membrane area of the organic solvent nanofiltration membrane is 20-40m 2 A/B/A membrane, preferably 20-30m 2 And/or a support.
According to the invention, the length of the membrane module of the organic solvent nanofiltration membrane is 0.8-1.2m, preferably 0.9-1.1m, and the diameter of the membrane module is 6-10 inches, preferably 7-9 inches. In the invention, the organic solvent nanofiltration membrane is purchased from Yingchang specialty Chemie under the brand PM280, and the membrane component is a coiled membrane with the length of 1m and the diameter of 8 inches.
According to the present invention, the heavy lubricant base oil filtrate contains a heavy lubricant base oil and a dewaxing solvent.
According to the invention, the heavy lubricant base oil is present in an amount of 15 to 25 wt.% and the dewaxing solvent is present in an amount of 75 to 85 wt.%, based on the total weight of the heavy lubricant base oil filtrate; preferably, the heavy lubricant base oil is present in an amount of from 18 to 24 weight percent and the dewaxing solvent is present in an amount of from 76 to 82 weight percent, based on the total weight of the heavy lubricant base oil filtrate.
According to the invention, the heavy lubricant base oil is a crude oil fraction having a boiling range of 557-700 ℃; preferably, the heavy lubricant base oil is selected from propane deasphalted oil.
According to the invention, the heavy lubricating oil base oil is from a luxury petrochemical heavy ketone workshop, and comprises the following components in percentage by weight: the heavy lubricant base stock was about 20% and the dewaxing solvent was about 80%.
According to the invention, the organic solvent is the same as or different from the dewaxing solvent, each being an aromatic hydrocarbon and C 3 -C 8 Is a mixture of monoketones of (2).
According to the present invention, preferably, the aromatic hydrocarbon is monoalkylbenzene and/or benzene, more preferably, the alkyl group in the monoalkylbenzene is C 1 -C 4 Further preferably, the aromatic hydrocarbon is selected from one or more of toluene, ethylbenzene and propylbenzene.
According to the present invention, preferably, the monoketone is selected from one or more of methyl ethyl ketone, acetone, 2-butanone, 2-pentanone, 3-pentanone and 2-hexanone.
According to the present invention, the organic solvent is preferably the same as the dewaxing solvent, and is a mixture of methyl ethyl ketone and toluene.
Preferably, the C 3 -C 8 Is associated with the monoketone of (2)The weight ratio of aromatic hydrocarbon is (50:50) - (75:25), namely, (1-3): 1, a step of; more preferably, the C 3 -C 8 The weight ratio of monoketone to aromatic hydrocarbon is (50:50) - (70:30), i.e., (1-2.5): 1.
according to the invention, the method further comprises: before step (1), the organic solvent nanofiltration membrane is washed. Specifically, in the invention, firstly, dewaxing solvent is added into a membrane separation device for membrane washing, after the membrane washing is finished, dewaxing solvent in an evacuation device is added into heavy base oil dewaxing filtrate for operation until flux stability and retention rate reach target requirements, and finally, the operation pressure of the system is regulated to a preset pressure, and the circulation flow of the system is unchanged.
According to the invention, the cleaning conditions include: the film washing time is 0.1-5h, preferably 0.5-4h, more preferably 1-3h; the film washing pressure is 0-5MPa, preferably 0.1-3MPa, more preferably 0.2-2MPa; the circulating flow rate of the film washing solvent is 1-20m 3 Preferably 5-18m 3 Preferably from 8 to 15m 3 /h。
According to a particularly preferred embodiment of the present invention, a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate, wherein said process comprises: the method comprises three steps of OSN membrane cleaning, OSN membrane high-pressure pretreatment and filtrate re-stabilization operation, and specifically:
(1) Firstly, adding a dewaxing solvent into a testing device, wherein the dewaxing solvent is a mixed solvent of butanone and toluene, and the mass ratio of the butanone to the toluene is (1-1.5): 1, starting a material conveying pump to control the pressure to be 0.2-2MPa, starting a circulating pump after 1-2min, and controlling the circulating flow to be 8-15m 3 And (h) performing a film washing test, and discharging a film washing solvent out of the system after washing the film for 1-3h;
(2) The dewaxing solvent of (1) is added to pretreat the OSN film. Adjusting the frequency of a material conveying pump to control the system pressure to be 4-6MPa, and preprocessing an OSN membrane, wherein the system temperature is maintained to be 25-35 ℃ in the whole experimental process until the flux of the nanofiltration membrane is stable, and the condition of stable flux of the nanofiltration membrane after the preprocessing comprises the following steps: the flux of the nanofiltration membrane is reduced by less than 1% in 24 hours; the permeation flux of the nanofiltration membrane is stabilized at 300-500L/branch/h;
(3) Then the solvent in the system is emptied, and the light-end base oil filtrate is gradually added into the system, wherein the filtrate is from a device for producing heavy ketone by lubricating oil, and the concentration of the light-end base oil in the filtrate is 19.3 percent. The circulation flow of the system is regulated to 7-8m 3 And/h, until the heavy lubricant base oil filtrate is re-stabilized, wherein the conditions for the heavy lubricant base oil filtrate re-stabilization include: the flux of the nanofiltration membrane is reduced by less than 1% within 24 hours, and the content of lubricating oil in the permeate liquid is 0.1% -2%; the driving is successful, wherein the conditions of the driving success comprise: the flux of the nanofiltration membrane is 300-500L/branch/h, and the content of lubricating oil in the permeate liquid is 0.1-2%.
In the present invention, the light-weight base oil is a heavy lubricating oil, and is the heaviest of the heavy lubricating oils.
The present invention will be described in detail by examples.
In the following examples and comparative examples:
the content parameter of the lubricating oil is measured by a thermogravimetric method; the flux of the membrane is directly read by the device with its own flowmeter.
Example 1
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
Starting an industrial-grade size OSN membrane of a light-weight base oil filtrate system, wherein the OSN membrane is an 8-inch membrane module of winning special chemical PM280 membrane, the membrane module is a roll-type membrane module, the diameter of the membrane module is 8 inches, and the length of the membrane module is 1m; OSN film having a film area of 24m 2 And/membrane, the molecular weight cut-off is 280Da.
(1) Firstly, adding dewaxing solvent into a membrane separation pilot test device, wherein the dewaxing solvent is mixed solvent of butanone and toluene, the mass ratio of the butanone to the toluene is 3:2, starting a feed pump to control the pressure to be 1MPa, starting a circulating pump after 1min, and controlling the circulating flow to be 10m 3 And (h) performing a film washing test, and discharging a film washing solvent out of the system after 2h of film washing;
(2) The dewaxing solvent of (1) is added to pretreat the OSN film. And (3) adjusting the frequency of a feed pump to control the system pressure to 4.5MPa for pretreatment of the OSN film, wherein the system temperature is maintained at 25 ℃ in the whole experimental process. The permeation flux of the membrane is gradually reduced from the initial 1300L/branch/h, and after 1.5 days, the permeation flux of the membrane is stabilized at about 750L/branch/h and does not change;
(3) Then the solvent in the system is emptied, and a light-end base oil filtrate is gradually added into the system, wherein the light-end base oil filtrate is from a device for producing heavy ketone by lubricating oil, and the light-end base oil concentration in the light-end base oil filtrate is 19.3 percent. The circulation flow of the system is regulated to 8m 3 And/h. The permeation flux gradually added into the membrane along with the heavy lubricating oil base oil is rapidly reduced from 750L/branch/h to 400L/branch/h along with the light-weight base oil, and the content of the test lubricating oil of the permeate is 6.3%;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 350L/branch/h after 5 days of operation, and taking the permeate body fluid to test the content of lubricating oil to be 5.3%;
the permeation flux of the membrane is hardly changed when the membrane is continuously operated, and the content of the lubricating oil is 2.1% when the permeate body fluid is taken again after the membrane is operated for 6 days;
and after 7 days of operation, the permeate is taken to test the content of the lubricating oil to be 1.0%, and the driving is successful.
Example 2
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
The OSN membrane and membrane separation apparatus are the same as in example 1.
(1) Firstly, adding dewaxing solvent (the dewaxing solvent is mixed solvent of butanone and toluene, wherein the mass ratio of the butanone to the toluene is 3:2) into a testing device, starting a feed pump to control the pressure to be 0.2MPa, starting a circulating pump after 1min, and controlling the circulating flow to be 15m 3 And (h) performing a film washing test, and discharging a film washing solvent out of the system after 3h of film washing;
(2) And adding dewaxing solvent to pretreat the OSN film. And (3) adjusting the frequency of a material conveying pump to control the system pressure to 4MPa for pretreatment of the OSN film, wherein the system temperature is maintained at 30 ℃ in the whole experimental process. The permeation flux of the membrane is gradually reduced from the initial 1350L/branch/h, and after 1.5 days, the permeation flux of the membrane is stabilized at about 760L/branch/h and does not change;
(3) The system was then purged of solvent and the same way as in example 1 was gradually added to the system with the light base oil filtrate. The circulation flow of the system is regulated to 7m 3 And/h. The permeation flux of the light-end base oil gradually added into the membrane is rapidly reduced from 760L/branch/h to 420L/branch/h, and the content of the permeate liquid test lubricating oil is 6.4 percent at the moment;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 360L/branch/h after 6 days of operation, and taking the permeate body fluid to test the content of lubricating oil to be 5.1%;
the permeation flux of the membrane is hardly changed after the membrane is continuously operated, and the content of the lubricating oil is 1.9% after 7 days of operation by taking the permeate body fluid again;
the content of the permeate test lubricating oil is 1.4% after 7 days of operation, and the content of the permeate test lubricating oil is 1.0% after 8 days of operation, so that the driving is successful.
Example 3
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
The OSN membrane and membrane separation apparatus are the same as in example 1.
(1) Firstly, adding dewaxing solvent (the dewaxing solvent is mixed solvent of butanone and toluene, wherein the mass ratio of the butanone to the toluene is 3:2) into a testing device, starting a feed pump to control the pressure to be 2MPa, starting a circulating pump after 1min, and controlling the circulating flow to be 8m 3 And (h) performing a film washing test, and discharging a film washing solvent out of the system after washing the film for 1 h;
(2) Adding dewaxing solvent to pretreat OSN film, increasing the frequency of material conveying pump to control the system pressure at 6MPa and the circulating flow rate at 8m 3 /h, during the whole experimental processThe system temperature was maintained at 35 ℃. The permeation flux of the membrane is gradually reduced from the initial 1800L/branch/h, and after 1.5 days, the permeation flux of the membrane is stable at about 1100L/branch/h and does not change;
(3) The system was then purged of solvent and the same way as in example 1 was gradually added to the system with the light base oil filtrate. The circulating flow of the system is controlled to be 8m 3 And/h. The permeation flux of the light-weight base oil gradually added into the membrane is rapidly reduced from 1100L/branch/h to 700L/branch/h, and the content of the test lubricating oil of the permeate is 6.4 percent;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 500L/branch/h after 3 days of operation, and taking the permeate body fluid to test the content of lubricating oil to be 5.0%;
the permeation flux of the membrane is hardly changed after the membrane is continuously operated, and the content of the lubricating oil is 1.5% after the membrane is operated for 4 days by taking the permeate body fluid again for testing;
and after 5 days of operation, the permeate is taken to test the content of the lubricating oil to be 0.8%, and the driving is successful.
Example 4
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
Dewaxing solvent was recovered from the light-cut base oil filtrate in the same manner as in example 1, except that:
in step (2), the OSN film is pretreated. And adjusting the frequency of a feed pump to control the system pressure to 5MPa for pretreatment of the OSN film, and maintaining the system temperature at 20 ℃ in the whole experimental process. The permeation flux of the membrane is gradually reduced from the initial 1300L/branch/h, and after 1.5 days, the permeation flux of the membrane is stabilized at about 750L/branch/h and does not change;
(3) The system was then purged of solvent and the same way as in example 1 was gradually added to the system with the light base oil filtrate. The circulation flow of the system is regulated to be 12m 3 And/h. The permeation flux of the light-weight base oil gradually added into the membrane is rapidly reduced from 750L/branch/h to 410L/branch/h, and the content of the test lubricating oil of the permeate is 6.3 percent;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 380L/branch/h after 6 days of operation, and taking the permeate body fluid to test the content of lubricating oil to be 5.1%;
the permeation flux of the membrane is hardly changed after the membrane is continuously operated, and the content of the lubricating oil is 3.8% after the membrane is operated for 7 days by taking the permeate body fluid again for testing;
and after 7 days of operation, taking the permeate to test the content of the lubricating oil to be 2.5%, and after 8 days of operation, taking the permeate to test the content of the lubricating oil to be 1.5%, and driving successfully.
Example 5
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
Dewaxing solvent was recovered from the light-cut base oil filtrate in the same manner as in example 1, except that:
in step (2), the OSN film is pretreated. And (3) adjusting the frequency of a feed pump to control the system pressure to 7MPa for pretreatment of the OSN film, and maintaining the system temperature at 40 ℃ in the whole experimental process. The permeation flux of the membrane is gradually reduced from the initial 2500L/branch/h, and after 1.5 days, the permeation flux of the membrane is stabilized around 1200L/branch/h and does not change;
(3) The system was then purged of solvent and the same way as in example 1 was gradually added to the system with the light base oil filtrate. The circulation flow of the system is regulated to be 5m 3 And/h. The permeation flux of the light-weight base oil gradually added into the membrane is rapidly reduced from 1280L/branch/h to 880L/branch/h, and the content of the test lubricating oil of the permeate is 6.5 percent;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 600L/branch/h after the operation for 6 days, and taking the permeate body fluid to test the content of lubricating oil to be 2.1%;
after 7 days of operation, the permeate body fluid was taken again to test the lubricating oil content to be 1.0%, but the flux of the membrane was reduced to 500L/min, the supporting layer of the membrane had signs of compaction, and the service life of the membrane was greatly damaged.
Example 6
This example illustrates a process for recovering dewaxing solvent from a heavy lubricant base stock filtrate using the process of the present invention.
Dewaxing solvent was recovered from the light-cut base oil filtrate in the same manner as in example 1, except that:
in step (2), the OSN film is pretreated. And adjusting the frequency of a feed pump to control the system pressure to 8MPa for pretreatment of the OSN film, and maintaining the system temperature at 50 ℃ in the whole experimental process. The permeation flux of the membrane is gradually reduced from the initial 3000L/branch/h, and after 1.5 days, the permeation flux of the membrane is stabilized around 1200L/branch/h and does not change;
(3) The system was then purged of solvent and the same way as in example 1 was gradually added to the system with the light base oil filtrate. The circulation flow of the system is regulated to be 1m 3 And/h. The permeation flux of the light-weight base oil gradually added into the membrane is rapidly reduced from 1200L/branch/h to 700L/branch/h, and the content of the test lubricating oil of the permeate is 6.6 percent;
continuously maintaining the pressure and the circulation flow to operate the device, gradually and slowly reducing the permeation flux of the membrane along with the increase of the operation time, reducing the permeation flux of the membrane to 500L/branch/h after 6 days of operation, and taking the permeate body fluid to test the content of lubricating oil to be 1.1%; the permeate flux of the continuously operating membrane continues to decrease, and the support layer of the membrane shows evidence of significant compaction.
Comparative example 1
The OSN membrane and membrane separation unit used, and the light-off base oil filtrate, experimental temperature, and example 1 were identical except that: the method comprises the steps of directly adding heavy lubricant base oil filtrate into a membrane separation device without flushing and preprocessing an organic nanofiltration membrane (OSN membrane), sequentially opening a feed pump and a circulating pump, adjusting the frequency of the feed pump to control the operation pressure to be 4.5MPa, and adjusting the frequency of the circulating pump to control the circulating flow of the filtrate to be 10m 3 And/h, wherein the permeation flux of the membrane is 800L/branch/h, and the content of the tested lubricating oil of the permeate body fluid is 6.5%;
continuing to operate the device, the permeation flux of the membrane is continuously reduced along with the increase of the operation time, and when the device is operated for 5 days, the permeation flux of the membrane is 500L/branch/h, and the content of the test lubricating oil of the permeate body fluid is 6.4%;
when the device is operated for 8 days, the permeation flux of the membrane is reduced to 380L/branch/h, and the content of lubricating oil in the permeation liquid is 6.3 percent;
when the device is operated for 10 days, the permeation flux of the membrane is reduced to 360L/branch/h, and the content of lubricating oil in the permeation liquid is 6.0%;
when the device is operated for 12 days, the permeation flux of the membrane is reduced to 350L/branch/h, and the content of lubricating oil in the permeation liquid is 5.1 percent;
when the device is operated for 15 days, the permeation flux of the membrane is stabilized at 340-350L/branch/h, and the lubricating oil content in the permeation liquid is 2.9%;
when the device is operated for 18 days, the permeation flux of the membrane is stabilized at 340-350L/branch/h, the content of lubricating oil in the permeation liquid is 1.2%, and the operation is successful.
Comparative example 2
The OSN membrane and membrane separation unit used, and the light-off base oil filtrate, experimental temperature, and example 2 were identical except that: the method comprises the steps of directly adding heavy lubricant base oil filtrate into a membrane separation device without flushing and preprocessing an organic nanofiltration membrane (OSN membrane), sequentially opening a feed pump and a circulating pump, adjusting the frequency of the feed pump to control the operation pressure to be 4MPa, and adjusting the frequency of the circulating pump to control the circulating flow of the filtrate to be 7m 3 And/h, wherein the permeation flux of the membrane is 850L/branch/h, and the content of the tested lubricating oil of the permeate body fluid is 6.5%;
continuing to operate the device, the permeation flux of the membrane is continuously reduced along with the increase of the operation time, and when the device is operated for 5 days, the permeation flux of the membrane is 530L/branch/h, and the content of the test lubricating oil of the permeate body fluid is 6.4%;
when the device is operated for 8 days, the permeation flux of the membrane is reduced to 400L/branch/h, and the content of lubricating oil in the permeation liquid is 6.3 percent;
when the device is operated for 10 days, the permeation flux of the membrane is reduced to 380L/branch/h, and the content of lubricating oil in the permeation liquid is 6.0 percent;
the permeation flux of the membrane is reduced to 360L/branch/h when the device is operated for 12 days, and the content of lubricating oil in the permeation liquid is 5.1 percent;
the permeation flux of the membrane is stabilized at 350-360L/branch/h when the device is operated for 15 days, and the lubricating oil content in the permeation liquid is 3.2%;
the permeation flux of the membrane is stabilized at 350-360L/branch/h when the device is operated for 18 days, and the lubricating oil content in the permeation liquid is 1.5%;
when the device is operated for 20 days, the permeation flux of the membrane is stabilized at 350-360L/branch/h, and the lubricating oil content in the permeation liquid is 1.0% and the operation is successful.
Comparative example 3
The OSN membrane and membrane separation unit used, and the light-off base oil filtrate, experimental temperature, and example 3 were identical except that: the organic nanofiltration membrane (OSN membrane) is not washed and pretreated, but light-removed base oil filtrate is directly added into a membrane separation device, a feed pump and a circulating pump are sequentially opened, the frequency of the feed pump is regulated to control the operation pressure to 6MPa, and the frequency of the circulating pump is regulated to control the filtrate circulating flow to 8m 3 And/h, wherein the permeation flux of the membrane is 1200L/branch/h, and the content of the tested lubricating oil of the permeate body fluid is 6.5%;
continuing to operate the device, the permeation flux of the membrane is continuously reduced along with the increase of the operation time, and when the device is operated for 5 days, the permeation flux of the membrane is 730L/branch/h, and the content of the test lubricating oil of the permeate body fluid is 6.4%;
when the device is operated for 7 days, the permeation flux of the membrane is reduced to 600L/branch/h, and the content of lubricating oil in the permeation liquid is 6.3 percent;
when the device is operated for 8 days, the permeation flux of the membrane is reduced to 500L/branch/h, and the content of lubricating oil in the permeation liquid is 5.8%;
the permeation flux of the membrane is stabilized at 490-500L/branch/h when the device is operated for 10 days, and the lubricating oil content in the permeation liquid is 2.8%;
the permeation flux of the membrane is stabilized at 490-500L/branch/h when the device is operated for 12 days, and the lubricating oil content in the permeation liquid is 1.3%;
the permeation flux of the membrane is stabilized at 490-500L/branch/h when the device is operated for 13 days, and the lubricating oil content in the permeation liquid is 1.0% of that of the device, so that the device is successfully started.
The results show that according to the embodiments 1-6 of the method provided by the invention, the solvent of the membrane separation system is used for preprocessing the membrane, so that the molecules of the functional layer material of the membrane can be stretched to the greatest extent, the membrane can adapt to the separation environment quickly, the interception effect of the membrane can be exerted in a shorter time, and the operating pressure is higher, and the supporting layer of the membrane provides a larger reaction force, so that the functional layer is sufficiently stably supported, the stability is good, the driving time can be shortened, and the obvious better effect is achieved.
Comparative example 1, comparative example 2 and comparative example 3 did not perform the washing and pretreatment process for the organic nanofiltration membrane (OSN membrane), and since the functional layer material of the membrane was not sufficiently stretched in the solvent environment, the functional layer material of the membrane was not quickly adapted to the separation environment, resulting in a long driving time.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (12)
1. A process for recovering dewaxing solvent from a heavy lubricant base stock filtrate, said process comprising:
(1) Under high pressure condition, the organic solvent nanofiltration membrane is contacted with an organic solvent for pretreatment until the flux of the nanofiltration membrane is stable; wherein the high pressure is 4-6MPa;
(2) Evacuating the organic solvent, and contacting the heavy lubricating oil base oil filtrate with the nanofiltration membrane obtained in the step (1) at a low operation circulation flow rate until the heavy lubricating oil base oil filtrate is operated again stably and the starting is successful; wherein the low operation circulation flow is 7-10m 3 /h；
Wherein, in step (1), the conditions for flux stabilization of the nanofiltration membrane after the pretreatment include: the flux of the nanofiltration membrane is reduced by less than 1% in 24 hours;
wherein in step (2), the conditions for the re-stable operation of the heavy lubricant base oil filtrate include: the flux of the nanofiltration membrane is reduced by less than 1% within 24 hours, and the content of lubricating oil in the permeate liquid is 0.1% -2%;
wherein, in the step (2), the conditions of successful driving include: the flux of the nanofiltration membrane is 300-500L/branch/h, and the content of lubricating oil in the permeate liquid is 0.1-2%.
2. The method of claim 1, wherein in step (1), the conditions for flux stabilization of the nanofiltration membrane after the pretreatment comprise: the permeation flux of the nanofiltration membrane is stabilized at 300-500L/branch/h.
3. The process according to claim 1, wherein the process is carried out at a temperature of 10-50 ℃.
4. The process according to claim 1, wherein the process is carried out at a temperature of 20-40 ℃.
5. The process according to claim 1, wherein the process is carried out at a temperature of 25-35 ℃.
6. The method of claim 1, wherein the organic solvent nanofiltration membrane has a molecular weight cut-off of 280-400Da;
and/or the membrane area of the organic solvent nanofiltration membrane is 20-40m 2 A support membrane;
and/or the length of the membrane component of the organic solvent nanofiltration membrane is 0.8-1.2m, and the diameter of the membrane component is 6-10 inches.
7. The method of claim 1, wherein the organic solvent nanofiltration membrane has a molecular weight cut-off of 300-380Da.
8. The method of claim 1, wherein the heavy lubricant base oil filtrate comprises a heavy lubricant base oil and a dewaxing solvent;
and/or, the heavy lubricant base oil is present in an amount of from 15 to 25 wt.% and the dewaxing solvent is present in an amount of from 75 to 85 wt.%, based on the total weight of the heavy lubricant base oil filtrate;
and/or, the heavy lubricant base oil is a crude oil fraction having a boiling range of 557-700 ℃;
and/or the heavy lubricant base oil is selected from propane deasphalted oil.
9. The method of claim 8, wherein the organic solvent is the same as or different from the dewaxing solvent, each being an aromatic hydrocarbon and C 3 -C 8 Is a mixture of monoketones of (2).
10. The method of claim 9, wherein the C 3 -C 8 The weight ratio of the monoketone to the aromatic hydrocarbon is (1-3): 1.
11. the method of any one of claims 1-10, wherein the method further comprises: before step (1), the organic solvent nanofiltration membrane is washed.
12. The method of claim 11, wherein the cleaning conditions comprise: the membrane washing time is 0.1-5h, the membrane washing pressure is 0.1-5MPa, and the circulating flow of the membrane washing solvent is 1-20m 3 /h。
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