CN112159489B - System and method for polymerization process in preparation of mPAO - Google Patents

Abstract

The invention relates to a system and a method for a polymerization process in preparation of mPAO, and mainly solves the problems that the prior art has small batch operation yield, long reaction residence time and can not reach the commercial industrial scale. By adopting the system and the method, the commercial continuous production of the primary metallocene PAO product on the industrial scale of 200 tons/year to 20000 tons/year on the nominal scale can be realized, the polymerization reactors are connected in series and in parallel by 1 to 8 stages, the residence time of the polymerization reaction is reduced to 0.4 to 6.0 hours from 2 to 20 hours in the prior art, the conversion rate of the alpha-olefin raw material in the polymerization reaction is 90.9 to 94.7 percent, the yield of the primary metallocene PAO product is 87.2 to 90.8 percent, and the system and the method can be applied to the polymerization process for preparing mPAO.

Description

System and method for polymerization process in preparation of mPAO

Technical Field

The invention relates to the field of mPAO production process, in particular to a system and a method for preparing a polymerization process in mPAO, which adopt alpha-olefin raw materials to continuously and industrially produce mPAO primary products in a commercial mode and can be used in the industrial production of high-grade lubricating oil mPAO.

Background

The high-grade lubricating oil mPAO product is a new generation of lubricating oil with an ultrahigh viscosity index, is obtained by catalyzing alpha-olefin polymerization by a single-active-center catalyst, has a uniform product structure, has a neat comb-shaped structure, and is free of impurities such as sulfur, aromatic hydrocarbons and the like. The mPAO lubricating oil product has an extremely high viscosity index and a lower pour point, and has good low-temperature service performance. Meanwhile, under various harsh use conditions, the mPAO product shows better oxidation stability and good shear stability, so that the mPAO product has the advantages of longer oil change period, better durability, capability of keeping the viscosity of lubricating oil and the like. The mPAO has excellent performance characteristics which can meet highly harsh use conditions, and is widely applied to the fields of high-grade automobiles, spaceflight, navigation, military, high-speed trains and the like, and the proportion of the mPAO high-grade lubricating oil in the lubricating oil is higher and higher in the future from the performance characteristics and application advantages of the mPAO.

The invention patent application number 200510112794.1 in the prior art discloses a preparation method of high viscosity index poly-alpha-olefin synthetic oil, which comprises the steps of firstly contacting an alpha-decene raw material with an active chromium catalyst in a tank reactor, carrying out polymerization reaction for 2-20 hours under the conditions of 0.1-2.0 MPaA and 100-250 ℃, then separating out the catalyst and unreacted raw materials, and finally carrying out hydrogenation treatment on a reaction product to obtain the poly-alpha-olefin synthetic oil. The invention patent application No. 201480070683.6 a process for polymerizing olefins discloses a process for polymerizing olefins in a polymerization reactor system, and specifically provides a process for polymerizing olefins in a polymerization reactor system. The invention patent application number 201810304643.3 discloses a polymerization reaction device for producing poly-alpha-olefin, and discloses a polymerization reaction kettle, a mechanical structure and a transmission mechanism in the reaction kettle, so that the purpose of full catalysis and difficult leakage is realized. The utility model discloses a high-efficient polymerization equipment of 201821446846.8 discloses a high-efficient polymerization equipment, including dissolving device, a plurality of reaction unit and storage device in advance, through technology pipeline series connection between the polymerization ware.

However, the invention patent application number 200510112794.1 in the prior art is only a laboratory scale batch preparation method of mPAO lubricating oil, and once applied to a large-scale industrial process production device, there is an "amplification effect", and the technical effect of commercial operation is unpredictable. The invention patent application No. 201480070683.6 and the invention patent application No. 201810304643.3 relate to a process flow of only a single polymerization reactor, can not be directly applied to the preparation of mPAO multistage polymerization process. The utility model patent application No. 201821446846.8 does not relate to the method and process flow for preparing mPAO lubricating oil, and is series connection between polymerization reactors, and can not be directly applied to the preparation mPAO series-parallel polymerization process. Thus, the prior art has the problems of small batch operation yield, long reaction residence time and incapability of reaching the commercial industrial scale.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a system and a method for preparing a polymerization process in mPAO in an industrial scale commercial continuous production mPAO process device with a nominal scale of 200 tons/year to 20000 tons/year, which can realize the commercial continuous production of a metallocene PAO primary product with the nominal scale of 200 tons/year to 20000 tons/year by adopting a metallocene/organic boron compound system to catalyze an alpha-olefin polymerization process. mPAO is a high-grade lubricating oil mPAO product obtained by catalyzing and polymerizing alpha-olefin by a metallocene catalyst system, wherein the metallocene catalyst is generally regarded as a third-generation PAO catalyst, and the mPAO is a long-chain alpha-olefin polymer which has a unique comb-shaped structure, a non-vertical side chain geometrical structure and a narrow molecular weight distribution of Mw/Mn of less than 2.5 and is obtained under the action of a single chiral active center of the metallocene catalyst. This unique polymer molecular structure possesses improved rheological and flow characteristics compared to conventional PAOs, which can provide better shear stability, lower pour point, and higher viscosity index. These characteristics determine the suitability of mPAO targets for high severity applications, including applications in high-end automotive, aerospace, marine, military, high speed train, and the like. The product can be used for preparing finished lubricating oil with higher shear stability, viscosity index and better low-temperature performance.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect the present invention provides a method for preparing a polymerization process in mPAO, comprising the steps of:

step one, carrying out polymerization reaction on fresh and returned refined alpha-olefin raw materials, a catalyst and a cocatalyst, and adding hydrogen from outside into a polymerization reactor; the polymerization reaction is heated to the reaction temperature by steam, and the exothermic heat of the polymerization reaction is removed by circulating cooling water;

step two, the reaction liquid automatically flows into a next-stage polymerization reactor or enters the next-stage polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level; then the reaction liquid automatically flows into or enters the final stage polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level;

step three, after the reaction is finished, discharging the reaction liquid into a catalyst adsorption tank, wherein the reaction liquid contains a metallocene PAO primary product, an unreacted alpha-olefin raw material, an alpha-olefin dimer and a catalyst;

step four, the reaction liquid after the catalyst is filtered and removed enters an octene separator, and a metallocene PAO primary product flows out of the octene separator and enters an oligomer separator; the alpha-olefin raw material is evaporated from the top of the octene separator, condensed by an octene condenser, enters an octene condensate tank, and is conveyed to a light component buffer tank through an octene condensate pump;

fifthly, pumping out the metallocene PAO primary product at the bottom from a discharge pump of the oligomer separator after the metallocene PAO primary product enters the oligomer separator to separate alpha-olefin dimer;

evaporating alpha-olefin dimer generated by polymerization reaction from the top of an oligomer separator, condensing by a vacuum tail gas condenser, feeding into a vacuum tail gas condensate tank, and conveying to a light component buffer tank by a vacuum tail gas condensate pump;

and seventhly, conveying the unreacted alpha-olefin raw material and the alpha-olefin dimer in the light component buffer tank to a raw material refining unit for recycling by a light component recycling pump regularly.

Further, the reaction pressure of the polymerization reactor is 0.1-2.0 MPaA; preferably, the reaction pressure of the polymerization reactor is 0.2 to 1.6MPaA; more preferably, the polymerization reactor has a reaction pressure of 0.4 to 1.2MPaA.

Further, the reaction temperature of the polymerization reactor is 100-250 ℃; preferably, the reaction temperature of the polymerization reactor is 120 to 230 ℃; more preferably, the reaction temperature of the polymerization reactor is 140 to 210 ℃.

Further, the reaction residence time of the polymerization reactor is 0.4 to 6.0 hours; preferably, the reaction residence time of the polymerization reactor is 0.8 to 5.0h; more preferably, the reaction residence time of the polymerization reactor is between 1.2 and 4.0h.

Further, the polymerization reactors may be connected in series, in parallel, or in series-parallel.

Further, the number of polymerization reactor stages is 1 to 8; preferably, the number of polymerization reactor stages is from 2 to 7; more preferably, the number of polymerization reactor stages is 3 to 6.

Further, the operating pressure of the octene separator is 20-400 kPaA; preferably, the octene separator is operated at a pressure of 60 to 300kPaA; more preferably, the octene separator is operated at a pressure in the range of 100 to 200kPaA.

Further, the top operating temperature of the octene separator is 70-130 ℃; preferably, the top operating temperature of the octene separator is 80-120 ℃; more preferably, the octene separator has a top operating temperature of 90 to 110 ℃.

Further, the bottom operating temperature of the octene separator is 170-230 ℃; preferably, the bottom operating temperature of the octene separator is 180 to 220 ℃; more preferably, the octene separator has a bottom operating temperature of 190 to 210 ℃.

Further, the operating pressure of the oligomer separator is 2 to 120kPaA; preferably, the oligomer separator is operated at a pressure of from 10 to 100kPaA; more preferably, the oligomer separator is operated at a pressure of from 20 to 80kPaA.

Further, the top operating temperature of the oligomer separator is 130-200 ℃; preferably, the top operating temperature of the oligomer separator is 140 to 190 ℃; more preferably, the top operating temperature of the oligomer separator is 150 to 180 ℃.

Further, the bottom operating temperature of the oligomer separator is 220-260 ℃; preferably, the bottom operating temperature of the oligomer separator is 225 to 255 ℃; more preferably, the bottom operating temperature of the oligomer separator is 230 to 250 ℃.

Further, the adsorbent in the catalyst adsorption tank is a diatomite adsorbent; adding the diatomite adsorbent into an adsorbent feeding tank under the nitrogen seal, then feeding the diatomite adsorbent into a catalyst adsorption tank, and fully adsorbing the catalyst and the cocatalyst in the reaction liquid by the diatomite adsorbent under the stirring of a catalyst adsorption tank stirrer.

The second aspect of the invention provides a system for preparing the polymerization process in mPAO based on the method, which comprises a polymerization reactor, a catalyst adsorption tank, a catalyst adsorbent filter, an octene separation feed buffer tank, an octene separator, an oligomer separator and an oligomer separator discharge pump in sequence according to the sequence of end-to-end connection of pipelines;

in addition, the middle part of the oligomer separator is communicated with an oligomer condensate tank, an oligomer condensate pump and a light component buffer tank through pipelines;

the top of the oligomer separator is communicated with a vacuum tail gas condenser, a vacuum tail gas condensate tank, a vacuum tail gas condensate pump and a light component buffer tank through pipelines;

the top of the octene separator is communicated with an octene condenser, an octene condensate tank, an octene condensate pump and a light component buffer tank through pipelines;

the bottom of the light component buffer tank is communicated with a light component recycling pump through a pipeline.

Further, the system for preparing the polymerization process in mPAO also comprises an adsorbent feeding tank which is communicated with the top of the catalyst adsorption tank through a pipeline.

By adopting the technical scheme, compared with the prior art, the invention has the following technical effects:

the invention relates to a system and a method for preparing a polymerization process in mPAO (multi-metallocene-olefin) and can realize commercial continuous production of a primary metallocene PAO product in an industrial scale of 200-20000 tons per year on a nominal scale, polymerization reactors are connected in series and in parallel by 1-8 levels, the residence time of the polymerization reaction is reduced to 0.4-6.0 h from 2-20 h in the prior art, the conversion rate of an alpha-olefin raw material in the polymerization reaction is 90.9-94.7%, and the yield of the primary metallocene PAO product is 87.2-90.8%, so that a better technical effect is obtained.

Drawings

FIG. 1 is a flow diagram of a polymerization process in the preparation of mPAO according to the present invention;

wherein, 1, a first-stage polymerization reactor; 2. a second stage polymerization reactor; 3. a three-stage polymerization reactor; 4. a catalyst adsorption tank; 5. an octene separation feed surge tank; 6. an octene separator; 7. an oligomer separator; 8. an adsorbent feed tank; 9. a catalyst sorbent filter; 10. an oligomer condensate tank; 11. a vacuum tail gas condensate tank; 12. an octene gel tank; 13. a light component buffer tank; 14. an octene condenser; 15. a vacuum tail gas condenser; 16. an octene condensate pump; 17. a vacuum tail gas condensate pump; 18. an oligomer condensate pump; 19. a discharge pump of the oligomer separator; 20. a light component recycling pump; 21. a catalyst M; 22. a cocatalyst B; 23. a cocatalyst T; 24. refining the alpha-olefin feedstock; 25. hydrogen gas; 26. a diatomaceous earth adsorbent; 27. a non-condensable gas E; 28. a non-condensable gas F; 29. unreacted alpha-olefin feed and alpha-olefin dimer; 30. primary products of metallocene PAO;

the process flow is as follows:

taking a 3-stage polymerization reactor in series as an example, fresh and returned refined α -olefin raw material 24, catalyst M21, cocatalyst B22 and cocatalyst T23 enter first-stage polymerization reactor 1, second-stage polymerization reactor 2 and third-stage polymerization reactor 3, respectively. Hydrogen 25 from the outside is also fed to the first polymerization reactor 1, the second polymerization reactor 2 and the third polymerization reactor 3. Heating the first-stage polymerization reactor 1, the second-stage polymerization reactor 2 and the third-stage polymerization reactor 3 to reaction temperature by steam when starting, carrying out polymerization reaction on the refined alpha-olefin raw material 24 under the catalytic action of the catalyst M21, the cocatalyst B22 and the cocatalyst T23, removing the heat of the polymerization reaction by circulating cooling water, and controlling the reaction residence time by controlling the liquid level in the first-stage polymerization reactor 1. The reaction liquid flows into the second-stage polymerization reactor 2 from the first-stage polymerization reactor 1 automatically or by using pressure difference, and the second-stage polymerization reactor 2 controls the reaction residence time by controlling the liquid level. Then the reaction liquid flows into the third-stage polymerization reactor 3 from the second-stage polymerization reactor 2 automatically or by using pressure difference, and the third-stage polymerization reactor 3 controls the reaction residence time by controlling the liquid level. After the reaction is finished, the reaction solution is discharged into a catalyst adsorption tank 4, and the reaction solution contains a metallocene PAO initial product 30, an unreacted purified alpha-olefin raw material 24, an alpha-olefin dimer, a catalyst M21, a cocatalyst B22 and a cocatalyst T23. The diatomite adsorbent 26 is added into the adsorbent feeding tank 8 under the nitrogen seal, then enters the catalyst adsorption tank 4, the catalyst M21 and the cocatalyst in the reaction liquid are adsorbed by the diatomite adsorbent 26, and the diatomite adsorbent 26 sufficiently adsorbs the catalyst M21 and the cocatalyst under the stirring of the stirrer of the catalyst adsorption tank 4. The reaction liquid passes through a catalyst adsorbent filter 9 to filter out a catalyst M21, a cocatalyst and a diatomite adsorbent 26, enters an octene separation feeding buffer tank 5, and then enters an octene separator 6. The metallocene PAO primary product 30 flows from the octene separator 6 into the oligomer separator 7. Unreacted alpha-olefin raw materials are evaporated from the top of the octene separator 6, condensed by an octene condenser 14 and then enter an octene condensate tank 12 for gas-liquid separation, non-condensable gas E27 is discharged outside, and the condensate is conveyed to a light component buffer tank 13 by an octene condensate pump 16. After the primary metallocene PAO product 30 enters the oligomer separator 7 to separate the alpha-olefin dimer, the primary metallocene PAO product 30 at the bottom is discharged out of the room by the discharge pump 19 of the oligomer separator. A part of alpha-olefin dimer generated by the polymerization reaction is evaporated from the top of the oligomer separator 7, condensed by the vacuum tail gas condenser 15, enters the vacuum tail gas condensate tank 11 for gas-liquid separation, the non-condensable gas F28 is discharged outside, and the condensate is conveyed to the light component buffer tank 13 by the vacuum tail gas condensate pump 17. Another part of the alpha-olefin dimer produced by the polymerization reaction is pumped out from the middle of the oligomer separator 7 into an oligomer condensate tank 10 and then is transferred to a light component buffer tank 13 by an oligomer condensate pump 18. The unreacted alpha-olefin raw material and alpha-olefin dimer 29 in the light component buffer tank 13 are periodically sent to the raw material refining unit for recycling by the light component recycling pump 20.

Detailed Description

The present invention provides a system and method for a polymerization process in the preparation of mPAO. The present invention will be described in detail and specifically with reference to the following examples to facilitate better understanding of the present invention, but the following examples do not limit the scope of the present invention.

Example one

Referring to fig. 1, this example provides a system for the preparation of polymerization processes in mPAO with polymerization reactors in 3-stage series in a nominal 200 ton/year to 20000 ton/year commercial continuous production mPAO process plant. The system sequentially comprises a first-stage polymerization reactor 1, a second-stage polymerization reactor 2, a third-stage polymerization reactor 3, a catalyst adsorption tank 4, a catalyst adsorbent filter 9, an octene separation feeding buffer tank 5, an octene separator 6, an oligomer separator 7 and an oligomer separator discharging pump 19 according to the sequence of end-to-end connection of pipelines;

in addition, the middle part of the oligomer separator 7 is communicated with an oligomer condensate tank 10, an oligomer condensate pump 18 and a light component buffer tank 13 through pipelines;

the top of the oligomer separator 7 is communicated with a vacuum tail gas condenser 15, a vacuum tail gas condensate tank 11, a vacuum tail gas condensate pump 17 and a light component buffer tank 13 through pipelines;

the top of the octene separator 6 is communicated with an octene condenser 14, an octene condensate tank 12, an octene condensate pump 16 and a light component buffer tank 13 through pipelines;

the bottom 13 of the light component buffer tank is communicated with a light component recycling pump 20 through a pipeline.

The system for preparing the mPAO polymerization process also comprises an adsorbent feeding tank 8 which is communicated with the top of the catalyst adsorption tank 4 through a pipeline.

Example two

Referring to fig. 1, this example provides a method of using the system of example one to prepare a polymerization process in mPAO in a nominal scale 200 tons/year to 20000 tons/year commercial continuous production mPAO process plant, comprising the steps of:

step one, carrying out polymerization reaction on a fresh and returned refined alpha-olefin raw material 24, a catalyst M21, a cocatalyst B22 and a cocatalyst T23, and adding hydrogen 25 from outside into a polymerization reactor; the polymerization reaction is heated to the reaction temperature by steam, and the exothermic heat of the polymerization reaction is removed by circulating cooling water;

step two, the reaction liquid of the first-stage polymerization reactor 1 automatically flows into the second-stage polymerization reactor 2 or enters the second-stage polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level; then the reaction liquid automatically flows into a three-stage polymerization reactor 3 or enters the three-stage polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level;

step three, after the reaction is finished, discharging the reaction liquid into a catalyst adsorption tank 4, wherein the reaction liquid contains a metallocene PAO primary product 30, an unreacted alpha-olefin raw material 24, an alpha-olefin dimer and a catalyst;

step four, the reaction liquid after the catalyst is removed by filtration enters an octene separator 6, and a metallocene PAO primary product 30 flows out of the octene separator 6 and enters an oligomer separator 7; the alpha-olefin raw material is evaporated from the top of the octene separator 6, condensed by an octene condenser 14, enters an octene condensate tank 12, and is conveyed to a light component buffer tank 13 by an octene condensate pump 16;

fifthly, after the metallocene PAO primary product 30 enters an oligomer separator 7 to separate alpha-olefin dimer, the metallocene PAO primary product 30 at the bottom is pumped out by a discharge pump 19 of the oligomer separator;

sixthly, evaporating alpha-olefin dimer generated by the polymerization reaction from the top of the oligomer separator 7, condensing the alpha-olefin dimer by using a vacuum tail gas condenser 15, feeding the alpha-olefin dimer into a vacuum tail gas condensate tank 11, and conveying the alpha-olefin dimer to a light component buffer tank 13 by using a vacuum tail gas condensate pump 17;

and seventhly, sending the unreacted alpha-olefin raw material and the alpha-olefin dimer 29 in the light component buffer tank to a raw material refining unit for recycling by a light component recycling pump 20 periodically.

Wherein the reaction pressure in the polymerization reactor is in the range of 0.1 to 2.0MPaA, preferably in the range of 0.2 to 1.6MPaA, more preferably in the range of 0.4 to 1.2MpaA.

The reaction temperature of the polymerization reactor is 100 to 250 ℃, preferably in the range of 120 to 230 ℃, more preferably in the range of 140 to 210 ℃.

The reaction residence time in the polymerization reactor is from 0.4 to 6.0h, preferably from 0.8 to 5.0h, more preferably from 1.2 to 4.0h.

The operating pressure of the octene separator is in the range of 20 to 400kPaA, preferably in the range of 60 to 300kPaA, more preferably in the range of 100 to 200kPaA; the top operating temperature is 70-130 ℃, the preferred range is 80-120 ℃, and the more preferred range is 90-110 ℃; the bottom operating temperature is in the range of 170 to 230 c, preferably in the range of 180 to 220 c, more preferably in the range of 190 to 210 c.

The oligomer separator is operated at a pressure of from 2 to 120kPaA, preferably in the range of from 10 to 100kPaA, more preferably in the range of from 20 to 80kPaA; the top operating temperature is 130-200 ℃, the preferred range is 140-190 ℃, and the more preferred range is 150-180 ℃; the bottom operating temperature is 220 to 260 ℃, preferably in the range of 225 to 255 ℃, more preferably in the range of 230 to 250 ℃.

The adsorbent in the catalyst adsorption tank 4 is diatomite adsorbent 26; the diatomite adsorbent 26 is added into the adsorbent feeding tank 8 under the nitrogen seal, and then enters the catalyst adsorption tank 4, and the catalyst and the cocatalyst in the reaction solution are fully adsorbed by the diatomite adsorbent 26 under the stirring of the stirrer of the catalyst adsorption tank 4.

Comparative example 1

The mPAO polymerization reaction prepared by the prior art is on a laboratory scale, an intermittent production method is adopted, the retention time is 2-20 h, the conversion rate of alpha-olefin raw materials in the polymerization reaction is 84-88%, the yield of the metallocene PAO primary product is 82-86%, and the commercial continuous production of the metallocene PAO primary product on an industrial scale cannot be realized.

EXAMPLE III

This example provides a system and method for a polymerization process in the preparation of mPAO, with a nominal capacity of 1000 tons/year. The process flow is as follows:

hydrogen from outside is added into a polymerization reactor, fresh and returned refined alpha-olefin raw material, catalyst and cocatalyst are heated to the polymerization reaction temperature by steam and are also added into the polymerization reactor, the materials are subjected to polymerization reaction, and the exothermic heat of the polymerization reaction is removed by circulating cooling water. The reaction liquid automatically flows into the next stage of polymerization reactor or enters the next stage of polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level. Then the reaction liquid flows into the final stage polymerization reactor automatically or by using pressure difference, and the reaction residence time is controlled by controlling the liquid level. After the reaction is finished, the reaction liquid contains a metallocene PAO primary product, unreacted alpha-olefin, alpha-olefin dimer and a catalyst, and the reaction liquid is discharged into a catalyst adsorption tank to adsorb and remove the catalyst. And (3) enabling the reaction liquid after the catalyst is removed by adsorption to enter an octene separator, enabling a metallocene PAO primary product to flow out of the octene separator to enter an oligomer separator, and distilling unreacted alpha-olefin out of the top of the octene separator to be sent to a light component buffer tank. After the initial metallocene PAO product enters an oligomer separator to separate alpha-olefin dimer, the initial metallocene PAO product at the bottom is pumped out of the room by a discharge pump of the oligomer separator. Alpha-olefin dimer produced by the polymerization reaction is distilled out from the top of the oligomer separator and sent to a light component buffer tank, and unreacted alpha-olefin and alpha-olefin dimer collected by the light component buffer tank are periodically pumped to a raw material refining unit for recycling.

The process parameters of the embodiment are as follows: the reaction pressure of the polymerization reactor is 0.9MPaA, the reaction temperature is 162 ℃, the reaction retention time is 1.2h, the polymerization reactors are connected in parallel, and the number of the polymerization reactor is 4; the operating pressure of the octene separator is 110kPaA, the top operating temperature is 88 ℃, and the bottom operating temperature is 198 ℃; the operating pressure of the oligomer separator is 24kPaA; the top operating temperature was 156 ℃; the bottom operating temperature was 240 ℃.

By adopting the process system and the method, 1000 tons of metallocene PAO primary products can be continuously produced in an industrial scale commercial way, the conversion rate of alpha-olefin raw materials in the polymerization reaction for preparing the metallocene PAO primary products is 93.9 percent, the yield of the metallocene PAO primary products is 89.9 percent, and the international advanced level is reached.

Example four

A system and method for preparing a polymerization process in mPAO, as in example three, only the nominal capacity of the polymerization process was changed to 6000 tons/year. The process parameters of the embodiment are as follows: the reaction pressure of the polymerization reactor is 1.5MPaA, the reaction temperature is 195 ℃, the reaction residence time is 3.3h, the polymerization reactors are connected in series, and the number of the polymerization reactors is 6; the operating pressure of the octene separator is 220kPaA, the operating temperature at the top is 110 ℃, and the operating temperature at the bottom is 203 ℃; the oligomer separator was operated at 65kPaA, a top operating temperature of 177 ℃ and a bottom operating temperature of 249 ℃.

By adopting the process system and the method of the embodiment, 6000 tons/year of metallocene PAO primary products can be continuously produced in an industrial scale, the conversion rate of alpha-olefin raw materials in the polymerization reaction for preparing the metallocene PAO primary products is 94.7 percent, the yield of the metallocene PAO primary products is 90.8 percent, and the international advanced level is reached.

EXAMPLE five

A system and method for preparing a polymerization process in mPAO, as in example three, only the nominal capacity of the polymerization process was changed to 200 tons/year. The process parameters of the embodiment are as follows: the reaction pressure of the polymerization reactor is 0.2MPaA, the reaction temperature is 101 ℃, the reaction retention time is 0.5h, and the number of the polymerization reactor is 1 grade; the octene separator operating pressure is 25kPaA, the top operating temperature is 72 ℃ and the bottom operating temperature is 184 ℃; the oligomer separator was operated at a pressure of 5kPaA, a top operating temperature of 131 ℃ and a bottom operating temperature of 223 ℃.

By adopting the process system and the method of the embodiment, 200 tons/year of metallocene PAO primary products can be continuously produced in an industrial scale commercial mode, the conversion rate of alpha-olefin raw materials in the polymerization reaction for preparing the metallocene PAO primary products is 90.9 percent, the yield of the metallocene PAO primary products is 87.2 percent, and the international advanced level is achieved.

EXAMPLE six

A system and method for preparing a polymerization process in mPAO like example three, only the nominal capacity of the polymerization process was changed to 20000 tons/year. The process parameters of the embodiment are as follows: the reaction pressure of the polymerization reactor is 1.9MPaA, the reaction temperature is 249 ℃, the reaction residence time is 5.8 hours, the polymerization reactors are connected in series and in parallel, and the number of the polymerization reactor is 8; the octene separator operating pressure was 393kPaA, the top operating temperature was 129 ℃, and the bottom operating temperature was 217 ℃; the oligomer separator was operated at a pressure of 118kPaA, a top operating temperature of 197 ℃ and a bottom operating temperature of 258 ℃.

By adopting the process system and the method of the embodiment, 20000 tons/year of metallocene PAO primary products can be continuously produced in an industrial scale commercial manner, the conversion rate of alpha-olefin raw materials in the polymerization reaction for preparing the metallocene PAO primary products is 92.1%, the yield of the metallocene PAO primary products is 88.4%, and the international advanced level is reached.

The embodiments of the present invention have been described in detail, but the embodiments are merely examples, and the present invention is not limited to the embodiments described above. Equivalent modifications and substitutions of the present invention are within the scope of the present invention for any person skilled in the art. Accordingly, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be covered by the present invention.

Claims (7)

1. A method for preparing a polymerization process in mPAO, characterized in that in a mPAO process plant for commercial continuous production on an industrial scale with a nominal scale of 200 to 20000 tons/year, the method comprises the following steps:

step one, carrying out polymerization reaction on fresh and returned refined alpha-olefin raw materials, a catalyst and a cocatalyst, and adding hydrogen from outside into a polymerization reactor; the polymerization reaction is heated to the reaction temperature by steam, and the exothermic heat of the polymerization reaction is removed by circulating cooling water;

step two, enabling reaction liquid to flow into a next-stage polymerization reactor independently or enter the next-stage polymerization reactor by utilizing pressure difference, and controlling the reaction residence time by controlling the liquid level; then the reaction liquid automatically flows into or enters the final stage polymerization reactor by utilizing pressure difference, and the reaction residence time is controlled by controlling the liquid level;

step three, after the reaction is finished, discharging the reaction liquid into a catalyst adsorption tank, wherein the reaction liquid contains a metallocene PAO primary product, an unreacted alpha-olefin raw material, an alpha-olefin dimer and a catalyst;

step four, the reaction liquid after the catalyst is filtered and removed enters an octene separator, and a metallocene PAO primary product flows out of the octene separator and enters an oligomer separator; the alpha-olefin raw material is evaporated from the top of the octene separator, condensed by an octene condenser, enters an octene condensate tank, and is conveyed to a light component buffer tank through an octene condensate pump;

fifthly, pumping out the metallocene PAO primary product at the bottom from a discharge pump of the oligomer separator after the metallocene PAO primary product enters the oligomer separator to separate alpha-olefin dimer;

step six, evaporating alpha-olefin dimer generated by polymerization reaction from the top of an oligomer separator, condensing the alpha-olefin dimer by a vacuum tail gas condenser, feeding the alpha-olefin dimer into a vacuum tail gas condensate tank, and conveying the alpha-olefin dimer to a light component buffer tank by a vacuum tail gas condensate pump;

step seven, the unreacted alpha-olefin raw material and the alpha-olefin dimer in the light component buffer tank are periodically pumped to a raw material refining unit for recycling by a light component recycling pump;

the operating pressure of the octene separator is 20-400 kPaA, the operating temperature at the top is 70-130 ℃, and the operating temperature at the bottom is 170-230 ℃;

the oligomer separator has an operating pressure of 2-120 kPaA, a top operating temperature of 130-200 ℃ and a bottom operating temperature of 220-260 ℃.

2. The method of claim 1, wherein the polymerization reactor has a reaction pressure of 0.1-2.0 MPaA, a reaction temperature of 100-250 ℃, and a reaction residence time of 0.4-6.0 h.

3. The method of preparing a polymerization process in mPAO according to claim 1, characterized in that the polymerization reactors can be connected in series, in parallel or in series and parallel.

4. The method of preparing a polymerization process in mPAO according to claim 1, characterized in that the number of polymerization reactor stages is 1 to 8 stages.

5. The method of making a polymerization process in mPAO according to claim 1, characterized in that the adsorbent in the catalyst adsorption tank is diatomaceous earth adsorbent; and adding the diatomite adsorbent into an adsorbent feeding tank under nitrogen seal, then feeding the adsorbent into the catalyst adsorption tank, and fully adsorbing the catalyst and the cocatalyst in the reaction liquid by the diatomite adsorbent under the stirring of a catalyst adsorption tank stirrer.

6. A system for preparing a polymerization process in mPAO based on the method as claimed in any one of claims 1-5, wherein the polymerization reactor, the catalyst adsorption tank, the catalyst adsorbent filter, the octene separation feed buffer tank, the octene separator, the oligomer separator and the oligomer separator discharge pump are in order of pipeline end-to-end connection;

in addition, the middle part of the oligomer separator is communicated with an oligomer condensate tank, an oligomer condensate pump and a light component buffer tank through pipelines;

the top of the oligomer separator is communicated with a vacuum tail gas condenser, a vacuum tail gas condensate tank, a vacuum tail gas condensate pump and a light component buffer tank through pipelines;

the top of the octene separator is communicated with an octene condenser, an octene condensate tank, an octene condensate pump and a light component buffer tank through pipelines;

the bottom of the light component buffer tank is communicated with a light component recycling pump through a pipeline.

7. The system for preparing a polymerization process in mPAO according to claim 6, further comprising an adsorbent feed tank in communication with the top of the catalyst adsorption tank via a line.

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