WO2019105453A1 - 一种环氧烷烃生产方法和系统 - Google Patents

一种环氧烷烃生产方法和系统 Download PDF

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WO2019105453A1
WO2019105453A1 PCT/CN2018/118519 CN2018118519W WO2019105453A1 WO 2019105453 A1 WO2019105453 A1 WO 2019105453A1 CN 2018118519 W CN2018118519 W CN 2018118519W WO 2019105453 A1 WO2019105453 A1 WO 2019105453A1
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Prior art keywords
extractant
column
reboiler
stream
alkylene oxide
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PCT/CN2018/118519
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English (en)
French (fr)
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胡松
胡帅
杨卫胜
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中国石油化工股份有限公司
中国石油化工股份有限公司上海石油化工研究院
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Priority claimed from CN201711241136.1A external-priority patent/CN109851587B/zh
Application filed by 中国石油化工股份有限公司, 中国石油化工股份有限公司上海石油化工研究院 filed Critical 中国石油化工股份有限公司
Priority to JP2020529524A priority Critical patent/JP7066849B2/ja
Priority to KR1020207018148A priority patent/KR102458887B1/ko
Priority to SG11202005095WA priority patent/SG11202005095WA/en
Priority to BR112020010871-5A priority patent/BR112020010871A2/pt
Priority to RU2020121678A priority patent/RU2746482C1/ru
Priority to EP18883987.2A priority patent/EP3719009A4/en
Priority to US16/768,663 priority patent/US11773072B2/en
Publication of WO2019105453A1 publication Critical patent/WO2019105453A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D301/00—Preparation of oxiranes
    • C07D301/32—Separation; Purification
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
    • B01D3/322—Reboiler specifications
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
    • B01D3/324—Tray constructions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
    • B01D3/40—Extractive distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
    • C07D303/02—Compounds containing oxirane rings
    • C07D303/04—Compounds containing oxirane rings containing only hydrogen and carbon atoms in addition to the ring oxygen atoms

Definitions

  • the present invention relates to an alkylene oxide production process and an alkylene oxide production system.
  • Propylene oxide (PO) is mainly used in the production of polyether polyols, propylene glycol and propylene glycol ethers.
  • the yield in propylene derivatives is second only to polypropylene and is the second largest propylene derivative.
  • propylene oxide used in the production of polyether polyols accounted for 66% of total consumption, 17% for propylene glycol production, and 6% for propylene glycol ether production. .
  • the global production capacity of propylene oxide was 8.822 million tons, and in 2016 it exceeded 10 million tons. It is estimated that by 2020, the production capacity of propylene oxide will reach 12 million tons / year, and the demand will reach 10 million tons / year. In the long run, the outlook for the propylene oxide market worldwide remains positive.
  • 1,2-butylene oxide (BO) is a homologue to ethylene oxide (EO) and propylene oxide (PO), and its molecular formula is C 4 H 8 O (CAS No.: 106-88-7), which is a
  • EO ethylene oxide
  • PO propylene oxide
  • C 4 H 8 O CAS No.: 106-88-7
  • 1,2-butylene oxide can also be used in foams, synthetic rubbers, nonionic surfactants, etc., and can also be used as a diluent for nitrocellulose lacquers or as a standard material for chromatographic analysis.
  • the alkylene oxide products have strict requirements on water, aldehydes and isomers. Water will affect the hydroxyl value and foaming properties of the polymer. The aldehyde will cause the product to emit odor and affect people's health. The isomers are aggregated. Long-chain end-capping agents, therefore, the national standard and enterprise standards have strict requirements on product purity.
  • propylene oxide ⁇ 99.95%, water ⁇ 0.02%, acetaldehyde + propionaldehyde ⁇ 0.005%, acid ⁇ 0.003%.
  • the quality purity requirements of 1,2-butylene oxide qualified products in the BASF enterprise standard are: butylene oxide ⁇ 99.5%, butylene oxide isomer ⁇ 0.2%, total aldehyde ⁇ 0.05%, water ⁇ 0.03% .
  • the quality purity requirements of 1,2-butylene oxide superior products are: butylene oxide ⁇ 99.9%, butylene oxide isomer ⁇ 0.1%, total aldehyde ⁇ 0.015%, water ⁇ 0.005%.
  • the crude alkylene oxide formed by the reaction usually contains impurities such as water, methanol, acetone, methyl formate, etc., because these impurities form an azeotrope with the alkylene oxide or the relative volatility is close to 1, and the conventional rectification is difficult to reach the alkylene oxide product. standard.
  • the purification of alkylene oxides generally employs C7 to C20 linear and branched hydrocarbons and/or glycols as extractants.
  • the alkylene oxide purification process uses a mixture of C8 linear and branched alkanes as the extractant.
  • the addition of the extractant increases the relative volatility of the acetaldehyde, water, methanol and methyl formate to the alkylene oxide, and the acetaldehyde, water, methanol and methyl formate are removed from the top of the column, and the extractant is recycled.
  • 1,2-butylene oxide is hydrolyzed to form 1,2-butanediol, and the solubility of 1,2-butanediol in water is less than 1,2-butylene oxide.
  • 1,2-butylene oxide is reacted with methanol to form 1-butanediol monomethyl ether (ether bond formed on the carbon atom of the terminal epoxy group), 2-butanediol monomethyl ether (ether bond formed at 2 positions) On the carbon atom of the epoxy group).
  • 1-butanediol monomethyl ether and 2-butanediol monomethyl ether are slightly soluble in water.
  • 1,2-butylene oxide is polymerized to form a polymer such as dipolybutylene oxide or polybutylene oxide.
  • 1,2-butylene oxide is reacted with an active hydrogen-containing compound such as water, a glycol or a polyol to form a poly(1,2-butanediol ether) and a derivative thereof.
  • an active hydrogen-containing compound such as water, a glycol or a polyol
  • Poly(1,2-butanediol ether and its derivatives are non-volatile viscous liquids, colorless to brown, mostly soluble in ketones, alcohols, esters, hydrocarbons and halogenated hydrocarbons; lower molecular weight soluble in water, The water solubility decreases with increasing molecular weight and decreases with increasing temperature.
  • the method reduces the accumulation of reaction by-products and derivatives in the extractant by passing the effluent portion containing the extractant and the heavy component of the column liquid. Due to the low content of heavy components in the external stream of the column, in order to ensure the purity of the extractant, a large amount of extractant needs to be discharged, and a large amount of extractant is lost.
  • a method for purifying butene oxide by using an anion exchange resin and an adsorbent is disclosed, for example, in U.S. Patent 4,772,732.
  • the anion exchange resin removes acid and dehydrogenation impurities, while the adsorbent removes water from impurities of butylene oxide.
  • the purification steps may be carried out singly or in combination, and the process may be carried out batchwise in the reactor or continuously in a column or column.
  • the ion exchange resin selected is a sulfonated macroreticular anion exchange resin and the adsorbent is a molecular sieve.
  • the method has higher cost, and the adsorption and desorption process is also troublesome, and the processing amount is not large.
  • propylene oxide is hydrolyzed to form 1,2-propanediol.
  • 1,2-propanediol has a solubility in water of less than propylene oxide.
  • Propylene oxide reacts with methanol to form propylene glycol monomethyl ether.
  • Propylene oxide is polymerized to form a polymer such as dipropylene oxide or polypropylene oxide.
  • Propylene oxide reacts with an active hydrogen-containing compound such as water, glycol or polyol to form a polypropylene glycol ether and a derivative thereof.
  • an active hydrogen-containing compound such as water, glycol or polyol
  • the solubility of polypropylene glycol ether and its derivatives in water and the solubility in the organic phase are not large.
  • the current state of the art is that there is a need for a method for producing an alkylene oxide having a small loss of extractant, high purity of the cyclic extractant, high yield of alkylene oxide, and low energy consumption.
  • the object of the present invention is to overcome the aforementioned drawbacks of the prior art and to provide a method for producing an alkylene oxide having a small loss of extractant, a high yield of alkylene oxide, and a low energy consumption.
  • a first aspect of the invention relates to a method for producing an alkylene oxide, the method comprising the steps of:
  • a second aspect of the invention provides a method of producing an alkylene oxide, the method comprising:
  • a third aspect of the invention provides an alkylene oxide production system, the system comprising
  • the extractant purifier is disposed under the separation tower feed, and is used for purifying a part of the tower tank material of the separation tower to remove heavy components having a boiling point higher than the extractant.
  • a gas phase or gas liquid mixture light component which is primarily an extractant, is obtained and returned to the separation column.
  • a fourth aspect of the invention provides another alkylene oxide production system, the system comprising
  • the extracting agent purifier is disposed below the feeding position of the separation tower, and is configured to receive a part of the tower tank material of the separation tower and perform purification treatment to remove a boiling point higher than the extracting agent
  • the heavy component gives a gas phase or gas-liquid mixture light component which is primarily an extractant and is returned to the separation column.
  • the invention introduces a part of the separation tower column stream which is originally directly effluxed and recycled into the extractant purifier by adding an extractant purifier at the bottom of the existing separation tower, and removes mainly the diol,
  • the liquid phase heavy component of impurities such as alcohol ether is returned to the separation column, thereby improving the purity of the extractant, reducing the amount of the extracting agent, and reducing the amount of waste liquid discharged.
  • the invention can reduce the loss of the extractant and increase the yield of the alkylene oxide. More specifically, the purity of the extractant is increased by 0.1 to 2%, the loss of the extractant is only 0.01 to 0.1%, and the yield of the alkylene oxide is increased by 0.5 to 5%.
  • the foregoing method for producing an alkylene oxide provided by the present invention can also save energy. Specifically, the foregoing method for producing an alkylene oxide provided by the present invention reduces energy consumption by 1 to 10%.
  • the invention adopts the above-mentioned “chemicalization and zero reduction” extractant purification method, and only needs to add an extractant purifier to the existing device, preferably a kettle type reboiler, which has small changes to the existing device, small land occupation and small investment. The effect is very obvious and has a good industrial application prospect.
  • Figure 1 is a schematic flow diagram of a preferred embodiment of the method of the present invention.
  • FIG. 2 is a schematic flow chart of a method provided by the prior art document US 4402794.
  • first”, “second”, and “third” do not represent a prioritization, and are merely for distinguishing, for example, “first stream” and “second”.
  • the “first” and “second” and “third” in the “stock logistics” and “third logistics” are only to distinguish the three parts of the same source that are sent to different places.
  • the production process of the alkylene oxide includes the reaction, separation, refining and the like of the alkylene oxide.
  • the present invention mainly relates to an alkylene oxide refining unit, and more particularly to a purification process of the extracting agent.
  • the present invention relates to an alkylene oxide refining unit in an alkylene oxide production process, and more particularly to an alkylene oxide refining unit employing an extractive rectification system.
  • the crude alkylene oxide product and the extractant are subjected to extractive rectification in an extractive rectification column, and the bottom liquid containing the alkylene oxide and the extractant is discharged from the rectification column, preferably discharged from the rectification column and enters the separation.
  • the tower obtains an alkylene oxide product and an extractant, and a part of the extractant is returned to the separation column through a column reboiler, and most of the extractant is directly recycled or purified according to the purity/impurity concentration of the extractant in the extractant. ).
  • the diol and the alcohol ether will continue to form and circulate.
  • the concentration of impurities in the extractant reaches 10% by weight, the extraction ability decreases.
  • the impurity concentration in the extractant is generally controlled to be less than 2% by weight, that is, in the extractant.
  • the impurity concentration exceeds 2% by weight, the extractant is not directly recycled, and purification treatment is required.
  • the extractant is replenished in batches for approximately 2-3 years.
  • the inventors of the present invention have found that by adding a small extractant purifier, a part of the extractant is subjected to purification treatment and then returned to the separation column, thereby improving the purity of the circulating extractant and reducing the loss of the extractant and the energy consumption of the separation.
  • the extracting agent purifier may be a distillation column or a reboiler.
  • the extracting agent purifier is a reboiler, further preferably a kettle type reboiler, and the purified extractant may be free from a power device such as a power pump. Returning to the separation tower, thereby greatly improving economy.
  • one or more small reboilers are further added to the bottom of a conventional separation column equipped with a reboiler, that is, the separation tower is equipped with two or more reboilers, which is suitable for new plant construction. It is also suitable for upgrading old equipment. This can save equipment investment, reduce the loss of extractant and improve product quality for newly built equipment. It is also suitable for retrofitting and upgrading of old equipment. The modification range is small, the land occupation is small, the input is low, and the loss of extractant is reduced. .
  • the extractant purifier is disposed between a lower portion of the inlet of the separation column into which the stream containing the alkylene oxide and extractant is introduced to the column of the separation column.
  • the height of the tower refiller and the extractant purifier relative to the separation tower tank is such that the temperature difference between the tower refiller and the extractant purifier is ⁇ 5 ° C .
  • the main function of the extractant purifier is to purify the extractant, ideally, there is no temperature difference between the tower refiller and the extractant purifier and the tower of the separation tower, but In view of various influencing factors in the actual industrial production process, the present invention allows a temperature difference of ⁇ 5 ° C, preferably ⁇ 3 ° C, in the tower autoreboiler and the extractant purifier.
  • the column still reboiler and the extractant purifier of the present invention are each disposed in a column reactor of the separation column.
  • the tower kettle reboiler and the extractant purifier are both disposed in the tower of the separation tower to significantly increase the purity of the extractant, reduce the loss of the extractant, and increase the yield of the alkylene oxide.
  • the number of trays of the separation column is 15 to 80, counting from the top of the column to the bottom of the column, and the feeding position of the extracting agent purifier is located at the countdown 0 to 4, preferably the last 0 to 2 towers board.
  • the ratio of the heat exchange area of the bottoms reboiler to the reboiler as the extractant purifier is (5 to 2):1. That is, the ratio of the flow rate of the material entering the column autoreboiler and the reboiler as the extractant purifier is (5 to 2):1.
  • This embodiment only needs to add one or more reboilers to the existing alkylene oxide production unit, and the reboiler can be connected to the separation tower through a simple pipeline, and the purified extractant can be removed without an additional power pump. Returning to the separation tower, it is easy to rebuild, small footprint, low investment, and low energy consumption.
  • the additional reboiler divides the third stream into a low-boiling component and a high-boiling component having a boiling point higher than the extracting agent, and the low-boiling component is mainly an extracting agent, and is returned to the separation column in the form of a gas phase or a gas-liquid mixture.
  • the high-boiling component having a boiling point higher than the extracting agent is mainly an impurity such as a diol or an alcohol ether, and is discharged from the system.
  • the first partial stream is from 2 to 20% by weight of the total amount of the column stream of the separation column.
  • the content of the alkylene oxide obtained in the top of the alkylene oxide is not less than 99.95% by weight, the content of the extracting agent is not more than 0.05% by weight, and the extract obtained from the column is mainly extracted from the extractant.
  • the content of the agent is not less than 99% by weight, and the content of the alkylene oxide is not more than 1% by weight.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 60 to 130 ° C, the temperature at the top of the column is 30 to 80 ° C, and the pressure is 0.04 to 0.40 MPaG.
  • the ratio of the extractant to the alkylene oxide is (2 to 15):1, more preferably (3 to 10), in mole percent. More preferably, it is (5-7):1.
  • the bottoms reboiler is any one of a thermosiphon reboiler, a kettle reboiler and a forced circulation reboiler.
  • the alkylene oxide is an isomer of propylene oxide, butylene oxide or butylene oxide; more preferably the alkylene oxide is butylene oxide; particularly preferably the alkylene oxide is 1,2-butylene oxide.
  • the stream containing the alkylene oxide and the extractant may be derived from the extract product stream obtained after extractive rectification of the olefin epoxidation reaction product.
  • the amount of alkylene oxide in the stream is from 5 to 25% by weight.
  • Extractants used in the purification of alkylene oxides are well known.
  • C7-C20 linear and branched hydrocarbons and/or glycols are generally used as extractants.
  • a mixture of C8 linear and branched alkanes such as n-octane, isooctane, 2-methylheptane is used as the extractant. From the standpoint of reducing the cost of the extractant, it is preferred to select the mixture.
  • the column reactor stream of the separation column contains an extractant and a heavy component.
  • these heavy components include 1,2-butanediol, 1-butanediol monomethyl ether, 2-butanediol monomethyl ether, dipolybutylene oxide, (poly)polycyclic ring Oxybutane, poly 1,2-butanediol ether and derivatives thereof, or mixtures thereof.
  • these heavy components include 1,2-propanediol, propylene glycol monomethyl ether, dipolypropylene oxide, (poly)polypropylene oxide, polypropylene glycol ether and derivatives thereof, or a mixture thereof.
  • the separation effect of the extractive distillation is constant.
  • the present invention emphasizes that side reactions may occur in the refining process to form impurities of the diol and its derivatives, and the generation of these impurities is unavoidable, and these impurities may accumulate in the system. These impurities counteract the extractive distillation and reduce the extraction efficiency of the extractant.
  • the extractant is directly discharged, when the heavy component impurities in the extractant are as low as 2%, the efflux extractant accounts for 98%, and the extractant loses a large amount; when the heavy component impurity content is as high as 10%, the efflux extractant Still accounting for 90%, the loss of extractant has decreased, but the extraction efficiency of the extractant has been greatly reduced, resulting in an increase in the solvent ratio of the extractive distillation column and an increase in energy consumption.
  • the invention only adds a small extractant purifier, and can increase the concentration of the heavy component in the effluent stream (that is, the liquid phase heavy component obtained in the extractant purifier) by more than one time, and the loss of the efflux extractant is reduced by half. the above.
  • the content of the heavy component impurities in the circulating extracting agent does not exceed 50% of the direct venting scheme.
  • a direct venting scheme in order to improve the product quality of the alkylene oxide, the yield of the alkylene oxide will be lowered, otherwise the product quality cannot be guaranteed.
  • the crude alkylene oxide product and the extractant are sent to an extractive rectification column for extractive rectification, the raffinate is withdrawn from the top of the column, and the feed stream 1 containing the alkylene oxide and the extractant is
  • the column kettle is discharged into the separation column C, the alkylene oxide product stream 3 is removed from the top of the separation column, the extractant stream 2 is removed from the separation column kettle, and the bottom of the separation column C is provided with a column kettle reboiler A and an extractant purifier B.
  • the tower kettle reboiler feed stream 4 feeds a portion of the column reactor stream to the column kettle reboiler A to obtain a column kettle reboiler discharge stream 5, and the column kettle reboiler discharge stream 5 is recycled to the lower portion of the separation column C.
  • the extractant purifier feed stream 6 feeds a portion of the column autoclave stream to the extractant purifier B to obtain an extractant purifier discharge stream 8 as a gas phase light component and a heavy component impurity stream as a liquid phase heavy component -
  • the feed stream 1 containing 1,2-butylene oxide and extractant in Figure 2 is sent to separation column C, and the 1,2-butylene oxide product stream 31 is removed from the top of the separation column, the extractant
  • the stream 2 is removed from the bottom of the separation column, the bottom of the separation column C is provided with a column refiller A, and the bottom of the column refiller feed stream 4 is sent to the bottom of the column to be reheated in the reboiler A.
  • the reboiler discharge stream 5 is sent to the lower portion of the separation column C, and the extractant stream 2 is separated into a stream as a heavy component impurity stream-outflow stream 7 to be separated from the separation system. A larger amount of extractant is lost due to the elimination of the accumulation of reaction by-products and derivatives in the extractant by the efflux portion of the extractant and the heavy component.
  • the specific operating conditions for the crude product stream containing the alkylene oxide and the extractant stream entering the first rectification column for rectification are not particularly limited, for example, the method provided in CN108017598A can be used, and the present invention is no longer Narration.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 72 ° C, the temperature at the top of the column is 33 ° C, the pressure is 0.04 MPaG, the number of plates is 65; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 8:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler located at the 66th tray.
  • the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 3% by weight of the separation tower column flow, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 3 ° C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.99%, water ⁇ 10wtppm, acetaldehyde + propionaldehyde ⁇ 10wtppm, acid ⁇ 5wtppm, recovery rate is 99.80%, purity of extracting agent in the separation column is 99.5%, extractant Loss of 0.020%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 80 ° C, the temperature at the top of the column is 35 ° C, the pressure is 0.08 MPaG, the number of plates is 60; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 7:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler located at the 61st tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 5% by weight of the separated column bottoms, and the temperature difference between the column reboiler A and the extractant purifier B is ⁇ 2.4 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.98%, water ⁇ 10wtppm, acetaldehyde + propionaldehyde ⁇ 10wtppm, acid ⁇ 5wtppm, the recovery rate is 99.82%, the purity of the extraction agent in the separation column is 99.5%, and the extractant is lost. 0.025%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 89 ° C, the temperature at the top of the column is 40 ° C, the pressure is 0.12 MPaG, the number of plates is 60; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler located at the 61st tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 8% by weight of the separation tower column stream, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 2 ° C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, the water is ⁇ 10wtppm, the acetaldehyde + propionaldehyde is ⁇ 10wtppm, the acid is ⁇ 5wtppm, the recovery rate is 99.85%, the purity of the extraction agent in the separation column is 99.5%, and the extractant is lost. 0.028%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 96 ° C, the temperature at the top of the column is 45 ° C, the pressure is 0.16 MPaG, the number of plates is 55; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 5:1 in terms of mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, which is located in the 56th tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 10% by weight of the separated column bottoms, and the temperature difference between the column reboiler A and the extractant purifier B is ⁇ 1.6 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, the water is ⁇ 10wtppm, the acetaldehyde + propionaldehyde is ⁇ 10wtppm, the acid is ⁇ 5wtppm, the recovery rate is 99.89%, the purity of the extractant in the separation column is 99.5%, and the extractant is lost. 0.029%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 101 ° C, the temperature at the top of the column is 50 ° C, the pressure is 0.20 MPaG, the number of plates is 50; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 4:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler located at the 51st tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 13% by weight of the separation tower column stream, and the temperature difference between the column tank reboiler A and the extractant purifier B is ⁇ 1.2 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.98%, water ⁇ 0.02%, acetaldehyde + propionaldehyde ⁇ 0.005%, acid ⁇ 0.003%, the recovery rate is 99.86%, and the purity of the extraction agent in the separation column is 99.5%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 106 ° C, the temperature at the top of the column is 55 ° C, the pressure is 0.24 MPaG, the number of plates is 45; the extractant is a mixture of C8 alkane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 4:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, which is located in the 46th tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 5:1; the portion entering the extractant purifier accounts for 15% by weight of the separation tower column flow, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.99%, water ⁇ 10wtppm, acetaldehyde + propionaldehyde ⁇ 10wtppm, acid ⁇ 5wtppm, recovery rate is 99.85%, the purity of the extraction agent in the separation column is 99.5%, and the extractant is lost. 0.035%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 111 ° C, the temperature at the top of the column is 60 ° C, the pressure is 0.28 MPaG, the number of plates is 40; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, which is located in the 41th tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 4:1; the proportion of the portion entering the extractant purifier to the separation tower column stream is 7% by weight, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1.8 °C in the whole process.
  • the purity of the 1,2-epoxybutane stream at the top of the separation column is 99.98%, water ⁇ 10wtppm, acetaldehyde + propionaldehyde ⁇ 10wtppm, acid ⁇ 5wtppm, recovery rate is 99.85%, the purity of the extraction agent in the separation column is 99.5%, and the extractant is lost. 0.034%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 115 ° C, the temperature at the top of the column is 65 ° C, the pressure is 0.32 MPaG, the number of plates is 30; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, which is located in the 31th tray, and the ratio of the heat exchange area between the tower refiller A and the extractant purifier B is 3:1; the portion entering the extractant purifier accounts for 6% by weight of the separation tower column stream, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1.7 ° C in the whole process.
  • the purity of the 1,2-epoxybutane stream at the top of the separation column is 99.98%, water ⁇ 10wtppm, acetaldehyde + propionaldehyde ⁇ 10wtppm, acid ⁇ 5wtppm, recovery rate is 99.86%, purity of extractant in the separation column is 99.5%, loss of extractant 0.033%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 119 ° C, the temperature at the top of the column is 70 ° C, the pressure is 0.36 MPaG, the number of plates is 25; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is heated.
  • the siphon reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, located in the 26th tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 2:1; the portion entering the extractant purifier accounts for 6% by weight of the separation tower column stream, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1.8 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, water ⁇ 0.02%, acetaldehyde+propionaldehyde ⁇ 0.005%, acid ⁇ 0.003%, the recovery rate is 99.87%, and the purity of the extraction agent in the separation column is 99.5%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 119 ° C, the temperature at the top of the column is 70 ° C, the pressure is 0.36 MPaG, the number of plates is 25; the extractant is n-octane, In the feed stream containing 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is used.
  • the kettle type reboiler is located below the last tray, and the extractant purifier B is a kettle type reboiler, which is located in the 26th tray, and the ratio of the heat exchange area between the tower kettle reboiler A and the extractant purifier B is 2:1; the portion entering the extractant purifier accounts for 3% by weight of the separation tower column stream, and the temperature difference between the column tank reboiler A and the extractant purifier B is ⁇ 1.8 ° C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, water ⁇ 0.02%, acetaldehyde+propionaldehyde ⁇ 0.005%, acid ⁇ 0.003%, the recovery rate is 99.87%, and the purity of the extraction agent in the separation column is 99.5%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 119 ° C, the temperature at the top of the column is 70 ° C, the pressure is 0.36 MPaG, the number of plates is 25; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is forced Circulating reboiler, located below the last tray, extractant purifier B is a kettle reboiler, located in the 26th tray, the ratio of the heat exchange area of the tower reboiler A and the extractant purifier B is 2:1; the portion entering the extractant purifier accounts for 6% by weight of the separation tower column stream, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1.8 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, water ⁇ 0.02%, acetaldehyde+propionaldehyde ⁇ 0.005%, acid ⁇ 0.003%, the recovery rate is 99.87%, and the purity of the extraction agent in the separation column is 99.5%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 119 ° C, the temperature at the top of the column is 70 ° C, the pressure is 0.36 MPaG, the number of plates is 25; the extractant is n-octane, containing In the feed stream of 1,2-butylene oxide and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1 in mole percent, and the separation tower reboiler A is forced
  • the circulating reboiler is located below the last tray, and the extractant purifier B is a kettle reboiler, which is located in the 24th tray, and the ratio of the heat exchange area between the tower reboiler A and the extractant purifier B is 2:1; the portion entering the extractant purifier accounts for 6% by weight of the separation tower column stream, and the temperature difference between the tower tank reboiler A and the extractant purifier B is ⁇ 1.8 °C in the whole process.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column is 99.95%, the water is ⁇ 0.02%, the acetaldehyde + propionaldehyde is ⁇ 0.005%, the acid is ⁇ 0.003%, the recovery rate is 99.85%, and the purity of the extracting agent in the separation column is 99.5%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 103 ° C, the pressure is 0.22 MPaG, the number of plates is 60; the extractant is n-octane, containing 1,2-epoxy In the feed stream of the alkane and extractant, the ratio of extractant to 1,2-butylene oxide is 8:1 in mole percent, and the separation column reboiler A employs a forced circulation reboiler.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column was 99.95%, the recovery rate was 96.38%, the purity of the extractant in the separation column was 99.0%, and the loss of the extractant was 2.02%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 103 ° C, the pressure is 0.22 MPaG, the number of plates is 50; the extractant is n-octane, containing 1,2-epoxy In the feed stream of the alkane and extractant, the ratio of extractant to 1,2-butylene oxide is 6:1, and the separation column reboiler A employs a forced circulation reboiler.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column was 99.95%, the recovery rate was 98.50%, the purity of the extractant in the separation column was 99.0%, and the loss of the extractant was 2.20%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 103 ° C, the pressure is 0.22 MPaG, the number of plates is 45; the extractant is n-octane, containing 1,2-epoxy In the feed stream of the alkane and extractant, the ratio of extractant to 1,2-butylene oxide is 4:1 in mole percent, and the separation column reboiler A employs a forced circulation reboiler.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column was 99.95%, the recovery rate was 98.88%, the purity of the extractant in the separation column was 99.0%, and the loss of the extractant was 2.45%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 103 ° C, the pressure is 0.22 MPaG, the number of plates is 40; the extractant is n-octane, containing 1,2-epoxy In the feed stream of the alkane and extractant, the ratio of extractant to 1,2-butylene oxide is 3:1 in mole percent, and the separation column reboiler A employs a forced circulation reboiler.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column was 99.95%, the recovery rate was 97.13%, the purity of the extractant in the separation column was 99.0%, and the loss of the extractant was 2.62%.
  • the operating conditions of the separation column include: the gas phase temperature at the top of the column is 103 ° C, the pressure is 0.22 MPaG, and the number of trays is 35; the heavy component impurity stream - the external stream is sent to the water for washing and recycling Come back to reduce the loss of extractant, the extractant is n-octane, the feed stream containing 1,2-butylene oxide and extractant, in mole percent of extractant and 1,2-butylene oxide The ratio is 6:1, and the separation column reboiler A uses a forced circulation reboiler.
  • the purity of the 1,2-butylene oxide stream at the top of the separation column was 99.95%, the recovery rate was 97.58%, the purity of the extractant in the separation column was 99.00%, and the loss of the extractant was 1.72%.

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Abstract

本发明公开了一种环氧烷烃生产方法和系统，主要解决现有技术中重组分杂质累积导致萃取剂纯度下降、损失增加、环氧烷烃收率下降、能耗增加的问题。所述方法包括含环氧烷烃和萃取剂的物流在具有塔釜再沸器的分离塔中分离的步骤；其特征在于，分离塔塔釜物流中的一部分进入萃取剂净化器处理，得到的气相轻组分返回分离塔，液相重组分去后处理。所述方法可用于环氧烷烃的工业生产中。

Description

一种环氧烷烃生产方法和系统 技术领域
本发明涉及一种环氧烷烃生产方法和一种环氧烷烃生产系统。
背景技术
环氧丙烷(PO)主要用于聚醚多元醇、丙二醇和丙二醇醚的生产，在丙烯衍生物中的产量仅次于聚丙烯，是第二大丙烯衍生物。据统计，2011年，全球用于聚醚多元醇生产的环氧丙烷约占总消费量的66％，用于丙二醇生产的约占17％，用于丙二醇醚生产的环氧丙烷约占6％。2011年，全球环氧丙烷产能为882.2万吨，2016年已突破1000万吨。预计到2020年，环氧丙烷生产能力将达到1200万吨/年，需求量达到1000万吨/年。长期来看，世界范围内环氧丙烷市场前景依然乐观。
1,2-环氧丁烷(BO)同环氧乙烷(EO)和环氧丙烷(PO)属同系物，分子式为C 4H 8O(CAS号：106-88-7)，是一种具有三元环结构的物质，化学性质活泼，主要用作聚醚多元醇单体和其它合成材料的中间体。1,2-环氧丁烷还可以用于制泡沫塑料、合成橡胶、非离子型表面活性剂等，也可代替丙酮作为硝基漆的稀释剂，也可用作色谱分析的标准物质。
环氧烷烃产品对水、醛、同分异构体有严格要求，水会影响聚合物的羟值和发泡性能，醛会导致产品发出异味，影响人们身体健康，同分异构体是聚合长链的封端剂，因此，国标和企业标准中对产品纯度都有严格要求。
国标中环氧丙烷优等品质量纯度要求为：环氧丙烷≥99.95％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％。
BASF企业标准中1,2-环氧丁烷合格品质量纯度要求为：环氧丁烷≥99.5％，环氧丁烷同分异构体≤0.2％，总醛≤0.05％，水≤0.03％。
1,2-环氧丁烷优等品质量纯度要求为：环氧丁烷≥99.9％，环氧丁烷同分异构体≤0.1％，总醛≤0.015％，水≤0.005％。
反应生成的粗环氧烷烃中通常含有水、甲醇、丙酮、甲酸甲酯等杂质，因为这些杂质与环氧烷烃形成共沸物或相对挥发度接近于1，普通精馏难以达到环氧烷烃产品标准。
环氧烷烃的纯化一般采用C7～C20直链和支链烃类和/或二醇类作为萃取剂。从经 济性考虑，环氧烷烃的纯化过程采用C8直链和支链烷烃的混合物作为萃取剂。萃取剂的加入使乙醛、水、甲醇、甲酸甲酯对环氧烷烃的相对挥发度变大，乙醛、水、甲醇、甲酸甲酯从塔顶移出，萃取剂回收利用。
因为粗环氧丁烷中含有水、甲醇，分离时又加入水，因此，在环氧丁烷精制过程中，会发生下列反应：
Figure PCTCN2018118519-appb-000001
1,2-环氧丁烷水解生成1,2-丁二醇，且1,2-丁二醇在水中的溶解度小于1,2-环氧丁烷。
1,2-环氧丁烷与甲醇反应生成1-丁二醇单甲醚(醚键形成在末端环氧基的碳原子上)、2-丁二醇单甲醚(醚键形成在2位环氧基的碳原子上)。且1-丁二醇单甲醚和2-丁二醇单甲醚都微溶于水。
1,2-环氧丁烷发生聚合反应生成聚合物，如二聚环氧丁烷、聚环氧丁烷。
1,2-环氧丁烷与水、二元醇或多元醇等含活性氢的化合物反应生成聚1,2-丁二醇醚及其衍生物。聚1,2-丁二醇醚及其衍生物是不挥发性粘稠液体，无色至棕色，大都溶于酮、醇、酯、烃类和卤代烃；分子量较低的溶于水，水溶性随分子量增加而下降，随温度增加而下降。
以上反应副产物及衍生物大多难溶于水，通过水洗的方法难以脱除。采用萃取精馏的方法进行环氧丁烷精制时，这些副产物及衍生物会在萃取剂中累积，从而降低了萃取剂的萃取效果。所以，降低萃取剂中这些副产物及衍生物的浓度是非常必要的。
例如，文献US4402794公开采用C7-C9的烃类，优选正辛烷作为萃取剂单次萃取精馏分离粗1,2-环氧丁烷溶液中含有的水、甲醇、丙酮、甲酸甲酯等杂质，但是其中没有涉及到杂质醛类的分离。萃取蒸馏塔塔顶分相器分层后的有机层去精馏塔蒸馏分离甲醇、丙酮等；萃取蒸馏塔塔釜物流送入萃取精馏塔；萃取精馏塔塔釜液部分外排。该方 法通过外排部分含萃取剂和重组分的塔釜液，以减少反应副产物及衍生物在萃取剂中的累积。由于塔釜外排部分物流中的重组分含量低，为保证萃取剂纯度，就需要外排大量的萃取剂，因而会损失较大量的萃取剂。
又如文献US4772732公开了一种通过使用阴离子交换树脂和吸附剂纯化丁烯氧化物的方法。阴离子交换树脂除去酸和脱氢杂质，而吸附剂除去来自环氧丁烷的杂质的水。根据杂质含量，纯化步骤可以单独或组合进行，并且该过程可以在反应器中分批进行，或者在塔或柱内连续进行。所选择的离子交换树脂是磺化的大网状阴离子交换树脂，吸附剂是分子筛。该方法成本较高，吸附解吸过程也会较麻烦，且处理量不大。
同样，在环氧丙烷体系中，环氧丙烷水解生成1,2-丙二醇。1,2-丙二醇在水中的溶解度小于环氧丙烷。环氧丙烷与甲醇反应生成丙二醇单甲醚。环氧丙烷发生聚合反应生成聚合物，如二聚环氧丙烷、聚环氧丙烷。
环氧丙烷与水、二元醇或多元醇等含活性氢的化合物反应生成聚丙二醇醚及其衍生物。聚丙二醇醚及其衍生物在水中的溶解度和有机相中溶解度都不大。
综上，现有技术目前的现状是，亟需一种萃取剂损失小、循环萃取剂纯度高、环氧烷烃收率高、能耗小的环氧烷烃生产方法。
发明内容
本发明的目的是克服现有技术的前述缺陷，提供一种萃取剂损失小、环氧烷烃收率高、能耗小的环氧烷烃生产方法。
具体而言，本发明的第一方面涉及一种环氧烷烃生产方法，该方法包括以下步骤：
1)将含有环氧烷烃和萃取剂及二醇、醇醚等重组分的物流在分离塔中精馏，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
2)将塔釜得到的主要为萃取剂的物流分为至少三股，其中第一股物流经塔釜再沸器加热后从塔釜返回分离塔，第二股物流作为循环萃取剂使用，第三股物流送入萃取剂净化器进行净化处理，除去其中沸点高于萃取剂的重组分，得到主要为萃取剂的气相或气液混合物轻组分；
3)将所述主要为萃取剂的气相或气液混合物轻组分返回所述分离塔。
本发明的第二方面提供另一种环氧烷烃生产方法，该方法包括：
1)将含环氧烷烃的粗产品物流与萃取剂及二醇、醇醚等重组分的送入萃取精馏塔进行萃取精馏，塔釜得到含有环氧烷烃和萃取剂及二醇、醇醚等重组分的物流，其中二 醇、醇醚包括含环氧烷烃的粗产品物流带入的，也包括在萃取精馏塔分离过程中发生化学反应产生的；
2)将含有环氧烷烃和萃取剂及二醇、醇醚等重组分的物流在分离塔中精馏分离，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
3)将塔釜得到的主要为萃取剂的物流分为至少三股，其中第一股物流经塔釜再沸器加热后从塔釜返回分离塔，第二股物流作为循环萃取剂进入萃取精馏塔使用，第三股物流送入萃取剂净化器进行净化处理，除去其中沸点高于萃取剂的二醇、醇醚等重组分，得到主要为萃取剂的气相或气液混合物轻组分；
4)将所述主要为萃取剂的气相或气液混合物轻组分返回所述分离塔。
本发明的第三方面提供一种环氧烷烃生产系统，该系统包括
1)分离塔，塔釜具有能够将塔釜物流引出所述分离塔的出口；
2)塔釜再沸器，设置在所述分离塔的下部，对所述分离塔的部分塔釜物料进行再沸后返回分离塔；
3)萃取剂净化器，所述萃取剂净化器设置在所述分离塔进料下方，用于对所述分离塔的部分塔釜物料进行净化处理，除去其中沸点高于萃取剂的重组分，得到主要为萃取剂的气相或气液混合物轻组分并返回至所述分离塔。
本发明第四方面提供另一种环氧烷烃生产系统，该系统包括
1)萃取精馏塔，用于对含环氧烷烃的粗产品物流进行萃取精馏；
2)分离塔，用于分离来自萃取精馏塔的塔釜物流，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
3)塔釜再沸器，设置在所述分离塔的下部，对所述分离塔的部分塔釜物料进行再沸后返回分离塔；
4)萃取剂净化器，所述萃取剂净化器设置在所述分离塔的进料位置的下方，用于接收所述分离塔的部分塔釜物料并进行净化处理，除去其中沸点高于萃取剂的重组分，得到主要为萃取剂的气相或气液混合物轻组分并返回至所述分离塔。
本发明提供的前述环氧烷烃生产方法具有如下具体的有益效果：
本发明通过在现有的分离塔的底部增设萃取剂净化器，将原先直接外排循环利用的分离塔塔釜物流中的一部分引入至萃取剂净化器中进行处理，除去其中主要为二醇、醇醚等杂质的液相重组分再返回所述分离塔，从而提高萃取剂的纯度，减少萃取剂的补充量，降低废液排放量。与现有技术萃取剂中杂质含量达到一定程度后定期排放萃取剂 并统一集中处理萃取剂中杂质的方式相比，本发明能够减少萃取剂的损失，提高环氧烷烃的收率。更具体地，萃取剂纯度提高了0.1～2％，萃取剂的损失仅为0.01～0.1％，环氧烷烃收率提高了0.5～5％。
并且，本发明提供的前述环氧烷烃生产方法还能够节约能耗，具体地，本发明提供的前述环氧烷烃生产方法能耗降低了1～10％。本发明通过上述“化整为零”的萃取剂净化方式，只需在现有装置基础上增设萃取剂净化器，优选釜式再沸器，对现有装置改动小，占地小，投资小，效果却非常明显，具有很好的工业应用前景。
附图说明
图1为本发明所述方法的一种优选的具体实施方式的流程示意图。
图2为现有技术文献US4402794提供的方法的流程示意图。
在附图中，相同的部件使用相同的附图标记。附图并不一定按照实际的比例。
附图标记说明：
1    进料物流                     2    萃取剂物流
3    环氧烷烃产品物流             31     1,2-环氧丁烷产品物流
4    塔釜再沸器进料物流           5    塔釜再沸器出料物流
6    萃取剂净化器进料物流         7    重组分杂质物流-外排物流
8    萃取剂净化器出料物流         A    塔釜再沸器
B    萃取剂净化器                 C    分离塔
具体实施方式
本说明书提到的所有出版物、专利申请、专利和其它参考文献全都通过引用并入本文。除非另有定义，本说明书所用的所有技术和科学术语都具有本领域技术人员常规理解的含义。在有冲突的情况下，以本说明书的定义为准。
当本说明书以词头“本领域技术人员公知”、“现有技术”或其类似用语来导出材料、物质、方法、步骤、装置或部件等时，该词头导出的对象涵盖本发明提出时本领域常规使用的那些，但也包括目前还不常用，却将变成本领域公认为适用于类似目的的那些。
在本说明书的上下文中，除了明确说明的内容之外，未提到的任何事宜或事项均直接适用本领域已知的那些而无需进行任何改变。而且，本文描述的任何实施方式均可 以与本文描述的一种或多种其他实施方式自由结合，由此而形成的技术方案或技术思想均视为本发明原始公开或原始记载的一部分，而不应被视为是本文未曾披露或预期过的新内容，除非本领域技术人员认为该结合是明显不合理的。
在本文中所披露的范围的端点和任何值都不限于该精确的范围或值，这些范围或值应当理解为包含接近这些范围或值的值。对于数值范围来说，各个范围的端点值之间、各个范围的端点值和单独的点值之间，以及单独的点值之间可以彼此组合而得到一个或多个新的数值范围，这些数值范围应被视为在本文中具体公开。
在本发明中，在没有明确说明的情况下，“第一”、“第二”、“第三”均不代表先后次序，仅是为了区分，例如，“第一股物流”和“第二股物流”和“第三股物流”中的“第一”和“第二”和“第三”仅是为了区分这是送入不同地方的三部分来源相同的物流。
需要说明的是，环氧烷烃的生产过程包括环氧烷烃的反应、分离、精制等单元，本发明中主要涉及环氧烷烃精制单元，尤其涉及其中萃取剂的纯化工艺。本发明涉及的是环氧烷烃生产工艺中的环氧烷烃精制单元，尤其是涉及采用萃取精馏方式的环氧烷烃精制单元。
一般的，环氧烷烃粗产品与萃取剂在萃取精馏塔中进行萃取精馏，含有环氧烷烃和萃取剂的塔釜液从精馏塔中排出，优选从精馏塔釜排出并进入分离塔，得到环氧烷烃产品和萃取剂，一部分萃取剂通过塔釜再沸器返回分离塔，大部分根据萃取剂中萃取剂的纯度/杂质的浓度确定萃取剂是直接循环利用还是进行纯化(再生)。在萃取精馏过程中，在有水和甲醇存在的情况下，二醇和醇醚将持续生成，循环累积。一般认为，萃取剂中杂质浓度达到10重量％时萃取能力下降，为了确保萃取精馏分离效果，降低分离过程能耗，一般控制萃取剂中杂质浓度低于2重量％，也即当萃取剂中杂质浓度超过2重量％时，不将萃取剂直接循环回用，而需净化处理。对于目前一般的工业装置，萃取剂约2-3年批量补充。
本发明的发明人发现，通过增设一个小型的萃取剂净化器，将一部分萃取剂经过净化处理后再返回分离塔，由此可以提高循环萃取剂的纯度，可以降低萃取剂的损耗和分离能耗。所述萃取剂净化器可以是蒸馏塔或再沸器，优选所述萃取剂净化器为再沸器进一步优选为釜式再沸器，净化后的萃取剂无需进一步的动力泵等动力装置即可返回分离塔，由此大大提高经济性。
本发明优选方案是在常规的配置有一个再沸器的分离塔的底部再增设一个或多个小再沸器，也就是说分离塔釜部配置有两个以上再沸器，适合新装置建设，也适合于旧装置升级改造。这对于新建装置来说，可节省设备投资，同时减少萃取剂损失量，提高产品质量；也特别适合旧装置改造升级，改动幅度小，占地小，投入低，减少萃取剂损失量，效果明显。
优选地，所述萃取剂净化器设置在所述分离塔的引入所述含有环氧烷烃和萃取剂的物流的入口的下部至所述分离塔的塔釜之间。由于越靠近塔釜的位置，环氧烷烃的含量越低，萃取剂和杂质二醇、醇醚等的含量越高，对提高萃取剂的纯度越有利，因此本发明优选所述萃取剂净化器设置在所述分离塔进料下方。优选情况下，所述塔釜再沸器和所述萃取剂净化器相对于所述分离塔塔釜的设置高度使得所述塔釜再沸器和所述萃取剂净化器中的温差≤5℃。在本发明中，所述萃取剂净化器的主要功能为纯化萃取剂，理想状态是所述塔釜再沸器和所述萃取剂净化器与所述分离塔的塔釜之间没有温差，但是，考虑到工业实际生产过程中的各种影响因素，本发明允许所述塔釜再沸器和所述萃取剂净化器中的温差≤5℃优选≤3℃。
根据一种特别优选的具体实施方式，本发明的所述塔釜再沸器和所述萃取剂净化器均设置在所述分离塔的塔釜。将所述塔釜再沸器和所述萃取剂净化器均设置在所述分离塔的塔釜能够明显提高萃取剂纯度，减少萃取剂的损失，提高环氧烷烃的收率。
优选地，所述分离塔的塔板数为15～80块，从塔顶往塔釜计数，所述萃取剂净化器的进料位置位于倒数第0～4块优选倒数第0～2块塔板。
优选情况下，所述塔釜再沸器与作为所述萃取剂净化器的再沸器的换热面积之比为(5～2):1。也即，进入所述塔釜再沸器和进入作为所述萃取剂净化器的再沸器的物料流量之比为(5～2):1。
该实施方式仅需在现有环氧烷烃生产装置基础上增加一个或多个再沸器，该再沸器与分离塔通过简单的管道相连即可，无需额外的动力泵将纯化后的萃取剂返回分离塔，因此改建容易、占地小、投资少、能耗低。
增设的再沸器将第三股物流分为低沸点组分和沸点高于萃取剂的高沸点组分，低沸点组分主要为萃取剂，以气相或气液混合物的形式返回分离塔循环利用，沸点高于萃取剂的高沸点组分主要为二醇、醇醚等杂质，外排出系统。
为了进一步提高本发明的方法中的萃取剂纯度，优选所述第一部分物流为由所述分离塔的塔釜物流的总量的2～20重量％。
优选地，塔顶得到的主要为环氧烷烃的物流中环氧烷烃的含量不低于99.95重量％，萃取剂的含量不高于0.05重量％，塔釜得到的主要为萃取剂的物流中萃取剂的含量不低于99重量％，环氧烷烃的含量不高于1重量％。
优选地，所述分离塔的操作条件包括：塔顶气相温度为60～130℃，塔顶温度为30～80℃，压力为0.04～0.40MPaG。
优选情况下，在含有环氧烷烃和萃取剂的物流中，以摩尔百分比计，所述萃取剂与所述环氧烷烃的比例为(2～15):1，更优选为(3～10):1，进一步优选为(5～7):1。
优选地，所述塔釜再沸器为热虹吸式再沸器、釜式再沸器和强制循环式再沸器中的任一种。
优选地，所述环氧烷烃为环氧丙烷、环氧丁烷或环氧丁烷的同分异构体；更优选所述环氧烷烃为环氧丁烷；特别优选所述环氧烷烃为1,2-环氧丁烷。
本发明中，含环氧烷烃和萃取剂的物流可以源自烯烃环氧化反应产物经萃取精馏后得到的萃取产物流。优选情况下，该物流中，环氧烷烃的含量为5～25重量％。
环氧烷烃纯化使用的萃取剂是被公知的。一般采用C7～C20直链和支链烃类和/或二醇类作为萃取剂。从经济性考虑，采用C8直链和支链烷烃的混合物作为萃取剂，所述C8直链和支链烷烃例如为正辛烷、异辛烷、2-甲基庚烷。从降低萃取剂成本考虑，优选选择混合物。
根据本发明，含环氧烷烃和萃取剂的物流在分离塔精馏后，分离塔的塔釜物流中含有萃取剂和重组分。以环氧丁烷为例，这些重组分包括1,2-丁二醇、1-丁二醇单甲醚、2-丁二醇单甲醚、二聚环氧丁烷、(多)聚环氧丁烷、聚1,2-丁二醇醚及其衍生物，或者它们的混合物。以环氧丙烷为例，这些重组分包括1,2-丙二醇、丙二醇单甲醚、二聚环氧丙烷、(多)聚环氧丙烷、聚丙二醇醚及其衍生物，或者它们的混合物。
需要说明的是，萃取剂纯度不变的情况下，萃取精馏的分离效果是一定的。但本发明强调的是，在精制过程中会发生副反应生成二醇及其衍生物杂质，而这些杂质的产生是不可避免的，并且这些杂质会在系统里累积循环。这些杂质对萃取精馏起反作用，降低萃取剂萃取效率。如果直接外排萃取剂，当萃取剂中重组分杂质低如2％时，外排萃取剂占比98％，萃取剂损失量大；当重组分杂质含量高如10％时，外排萃取剂仍然占比90％，萃取剂损失有所下降，但萃取剂萃取效率已经大幅度下降，导致萃取精馏塔溶剂比增加，能耗增大。本发明仅增加了一个小型萃取剂净化器，就可将外排物流(即萃取剂净化器中获得的液相重组分)中的重组分浓度提高1倍以上，外排萃取剂损失量降 低一半以上。采用本发明，萃取剂外排量相同的情况下，经过长周期运行，循环萃取剂中重组分杂质含量不超过直接外排方案的50％。而如果采用直接外排方案，为了提高环氧烷烃的产品质量，就会降低环氧烷烃收率，否则无法保证产品质量。
以下结合附图对本发明进行详细说明，但是需要指出的是，本发明的保护范围并不受此限制，而是由附录的权利要求书来确定。
根据本发明，在图1中，将环氧烷烃粗产品和萃取剂送入萃取精馏塔进行萃取精馏，萃余液从塔顶排出，含环氧烷烃和萃取剂的进料物流1从塔釜排出进入分离塔C，环氧烷烃产品物流3从分离塔顶部移出，萃取剂物流2从分离塔釜部移出，分离塔C底部设有塔釜再沸器A和萃取剂净化器B，塔釜再沸器进料物流4将一部分塔釜物流送入塔釜再沸器A加热后得到塔釜再沸器出料物流5，塔釜再沸器出料物流5循环回分离塔C下部，萃取剂净化器进料物流6将一部分塔釜物流送入萃取剂净化器B加热后得到作为气相轻组分的萃取剂净化器出料物流8和作为液相重组分的重组分杂质物流-外排物流7，其中，萃取剂净化器出料物流8返回分离塔C下部，重组分杂质物流-外排物流7从萃取剂净化器B底部排出。
与之相对的，图2中含有1,2-环氧丁烷和萃取剂的进料物流1送入分离塔C，1,2-环氧丁烷产品物流31从分离塔顶部移出，萃取剂物流2从分离塔釜部移出，分离塔C底部设有塔釜再沸器A，塔釜再沸器进料物流4将塔釜液送入塔釜再沸器A中加热后得到的塔釜再沸器出料物流5送入分离塔C下部，萃取剂物流2分出一股物流作为重组分杂质物流-外排物流7排出分离体系。由于通过外排部分萃取剂和重组分以减少反应副产物及衍生物在萃取剂中的累积，因而会损失较大量的萃取剂。
本发明对含环氧烷烃的粗产品物流与萃取剂物流进入第一精馏塔进行精馏的具体操作条件没有特别的限制，例如，可以采用CN108017598A中提供的方法进行，本发明在此不再赘述。
下面通过具体实例对本发明作进一步的阐述。以下实施例和对比例中的结果均取自系统稳定运行800小时后的结果。物料的纯度采用国标气相色谱GB/T9722-2006方法测得。以下“wtppm”表示重量ppm。
【实施例1】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为72℃，塔顶温度为33℃，压力为0.04MPaG，塔板数为65块；萃取剂为正辛烷，含有1,2-环氧丁烷和 萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为8：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第66块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为3重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤3℃。
分离塔顶部1,2-环氧丁烷物流纯度为99.99％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.80％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.020％。
【实施例2】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为80℃，塔顶温度为35℃，压力为0.08MPaG，塔板数为60块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为7：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第61块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为5重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤2.4℃。
分离塔顶部1,2-环氧丁烷物流纯度99.98％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.82％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.025％。
【实施例3】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为89℃，塔顶温度为40℃，压力为0.12MPaG，塔板数为60块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第61块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为8重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤2℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.85％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.028％。
【实施例4】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为96℃，塔顶温度为45℃，压力为0.16MPaG，塔板数为55块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为5：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第56块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为10重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.6℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.89％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.029％。
【实施例5】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为101℃，塔顶温度为50℃，压力为0.20MPaG，塔板数为50块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为4：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第51块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5:1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为13重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.2℃。
分离塔顶部1,2-环氧丁烷物流纯度99.98％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％，回收率99.86％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.032％。
【实施例6】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为106℃，塔顶温度为55℃，压力为0.24MPaG，塔板数为45块；萃取剂为C8烷烃混合物，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为4：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第46块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为5：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为15重量％，全过程中塔釜再沸 器A与萃取剂净化器B之间温差≤1℃。
分离塔顶部1,2-环氧丁烷物流纯度99.99％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.85％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.035％。
【实施例7】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为111℃，塔顶温度为60℃，压力为0.28MPaG，塔板数为40块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第41块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为4：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为7重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.8℃。
分离塔顶部1,2-环氧丁烷物流纯度99.98％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.85％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.034％。
【实施例8】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为115℃，塔顶温度为65℃，压力为0.32MPaG，塔板数为30块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第31块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为3：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为6重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.7℃。
分离塔顶部1,2-环氧丁烷物流纯度99.98％，水≤10wtppm，乙醛+丙醛≤10wtppm，酸≤5wtppm，回收率99.86％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.033％。
【实施例9】
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为119℃，塔顶温度为70℃，压力为0.36MPaG，塔板数为25块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔 塔釜再沸器A采用热虹吸式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第26块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为2：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为6重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.8℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％，回收率99.87％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.035％。
【实施例10】
本实施例采用与【实施例9】相似的工艺进行，所不同的是，本实施例的塔釜再沸器A采用釜式再沸器，具体地：
按照图1所示工艺流程图，分离塔的操作条件包括：塔顶气相温度为119℃，塔顶温度为70℃，压力为0.36MPaG，塔板数为25块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用釜式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第26块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为2：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为3重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.8℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％，回收率99.87％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.035％。
【实施例11】
本实施例采用与【实施例9】相似的工艺进行，所不同的是，本实施例的塔釜再沸器A采用强制循环式再沸器，具体地：
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为119℃，塔顶温度为70℃，压力为0.36MPaG，塔板数为25块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用强制循环式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第26块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为2：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为6重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.8℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％，回收率99.87％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.035％。
【实施例12】
本实施例采用与【实施例9】相似的工艺进行，所不同的是，本实施例的塔釜再沸器A采用强制循环式再沸器，具体地：
按照图1所示工艺流程，分离塔的操作条件包括：塔顶气相温度为119℃，塔顶温度为70℃，压力为0.36MPaG，塔板数为25块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔塔釜再沸器A采用强制循环式再沸器，位于最后一块塔板以下，萃取剂净化器B为釜式再沸器，位于第24块塔板，塔釜再沸器A与萃取剂净化器B换热面积之比为2：1；进入萃取剂净化器的部分占分离塔塔釜物流的比例为6重量％，全过程中塔釜再沸器A与萃取剂净化器B之间温差≤1.8℃。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，水≤0.02％，乙醛+丙醛≤0.005％，酸≤0.003％，回收率99.85％，分离塔釜部萃取剂纯度99.5％，萃取剂损失0.037％。
【比较例1】
按照图2所示工艺流程，分离塔的操作条件包括：塔顶气相温度为103℃，压力为0.22MPaG，塔板数为60块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为8：1，分离塔再沸器A采用强制循环式再沸器。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，回收率96.38％，分离塔釜部萃取剂纯度99.0％，萃取剂损失2.02％。
与【实施例1】相比，纯化每吨1,2-环氧丁烷的分离能耗增加4.5％。
【比较例2】
按照图2所示工艺流程，分离塔的操作条件包括：塔顶气相温度为103℃，压力为0.22MPaG，塔板数为50块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为6：1，分离塔再沸器A采用强制循环式再沸器。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，回收率98.50％，分离塔釜部萃取剂纯度99.0％，萃取剂损失2.20％。
【比较例3】
按照图2所示工艺流程，分离塔的操作条件包括：塔顶气相温度为103℃，压力为0.22MPaG，塔板数为45块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为4：1，分离塔再沸器A采用强制循环式再沸器。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，回收率98.88％，分离塔釜部萃取剂纯度99.0％，萃取剂损失2.45％。
【比较例4】
按照图2所示工艺流程，分离塔的操作条件包括：塔顶气相温度为103℃，压力为0.22MPaG，塔板数为40块；萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计，萃取剂与1,2-环氧丁烷的比例为3：1，分离塔再沸器A采用强制循环式再沸器。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，回收率97.13％，分离塔釜部萃取剂纯度99.0％，萃取剂损失2.62％。
【比较例5】
按照图2所示工艺流程，分离塔的操作条件包括：塔顶气相温度为103℃，压力为0.22MPaG，塔板数为35块；将重组分杂质物流-外排物流送去水洗后再循环回来，以减少萃取剂的损失，萃取剂为正辛烷，含有1,2-环氧丁烷和萃取剂的进料物流中，以摩尔百分比计萃取剂与1,2-环氧丁烷的比例为6：1，分离塔再沸器A采用强制循环式再沸器。
分离塔顶部1,2-环氧丁烷物流纯度99.95％，回收率97.58％，分离塔釜部萃取剂纯度99.00％，萃取剂损失1.72％。
与【实施例1】相比，纯化每吨1,2-环氧丁烷的分离能耗增加6.8％。

Claims (34)

  1. 一种环氧烷烃生产方法，该方法包括以下步骤：
    1)将含有环氧烷烃和萃取剂的物流在分离塔中蒸馏，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
    2)将塔釜得到的主要为萃取剂的物流分为至少三股，其中第一股物流经塔釜再沸器加热后从塔釜返回分离塔，第二股物流作为循环萃取剂使用，第三股物流送入萃取剂净化器进行净化处理，除去其中沸点高于萃取剂的液相重组分，得到主要为萃取剂的气相或气液混合物轻组分；
    3)将所述主要为萃取剂的气相或气液混合物轻组分返回所述分离塔。
  2. 根据权利要求1所述的方法，其中，所述第三股物流为由所述分离塔的塔釜得到的主要为萃取剂的物流的总量的2～20重量％。
  3. 根据权利要求1或2所述的方法，其中，塔顶得到的主要为环氧烷烃的物流中环氧烷烃的含量不低于99.95重量％，萃取剂的含量不高于0.05重量％，塔釜得到的主要为萃取剂的物流中萃取剂的含量不低于99重量％，环氧烷烃的含量不高于1重量％。
  4. 根据权利要求1-3中任意一项所述的方法，其中，所述萃取剂净化器为蒸馏塔或再沸器。
  5. 根据权利要求4所述的方法，其中，所述萃取剂净化器为再沸器，优选所述再沸器为釜式再沸器，进一步优选所述再沸器位于所述分离塔的进料口下方。
  6. 根据权利要求5所述的方法，其中，所述分离塔的塔釜再沸器与所述萃取剂净化器的换热面积之比为(5～2):1。
  7. 根据权利要求5或6所述的方法，其中，进入所述塔釜再沸器的第一股物流的温度和进入所述萃取剂净化器的第三股物流的温度塔釜相差≤5℃优选≤3℃。
  8. 根据权利要求1-7中任意一项所述的方法，其中，所述分离塔的操作条件包括：塔顶气相温度为60～130℃，塔顶温度为30～80℃，压力为0.04～0.40MPaG，塔板数为15～80 块。
  9. 根据权利要求1-8中任意一项所述的方法，其中，在含有环氧烷烃和萃取剂的物流中，以摩尔百分比计，所述萃取剂与所述环氧烷烃的比例为(2～15):1，优选为(3～10):1，更优选为(5～7):1。
  10. 根据权利要求1-9中任意一项所述的方法，其中，所述塔釜再沸器为热虹吸式再沸器、釜式再沸器和强制循环式再沸器中的任一种。
  11. 根据权利要求1-10中任意一项所述的方法，其中，所述环氧烷烃为环氧丙烷、环氧丁烷或环氧丁烷的同分异构体，优选所述环氧烷烃为环氧丁烷，更优选所述环氧烷烃为1,2-环氧丁烷。
  12. 一种环氧烷烃生产方法，该方法包括：
    1)将含环氧烷烃的粗产品物流与萃取剂物流送入精馏塔进行萃取精馏，塔釜得到含有环氧烷烃和萃取剂的物流；
    2)将含有环氧烷烃和萃取剂的物流在分离塔中蒸馏，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
    3)将塔釜得到的主要为萃取剂的物流分为至少三股，其中第一股物流经塔釜再沸器加热后从塔釜返回分离塔，第二股物流作为循环萃取剂使用，第三股物流送入萃取剂净化器进行净化处理，除去其中沸点高于萃取剂的液相重组分，得到主要为萃取剂的气相或气液混合物轻组分；
    4)将所述主要为萃取剂的气相或气液混合物轻组分送入返回所述分离塔。
  13. 根据权利要求12所述的方法，其中，所述第三股物流为由所述分离塔的塔釜得到的主要为萃取剂的物流的总量的2～20重量％。
  14. 根据权利要求12或13所述的方法，其中，塔顶得到的主要为环氧烷烃的物流中环氧烷烃的含量不低于99.95重量％，萃取剂的含量不高于0.05重量％，塔釜得到的主要为萃取剂的物流中萃取剂的含量不低于99重量％，环氧烷烃的含量不高于1重量％。
  15. 根据权利要求12-14中任意一项所述的方法，其中，所述萃取剂净化器为蒸馏塔或再沸器。
  16. 根据权利要求15所述的方法，其中，所述萃取剂净化器为再沸器，优选所述再沸器为釜式再沸器，进一步优选所述再沸器位于所述分离塔的中部或底部。
  17. 根据权利要求16所述的方法，其中，所述分离塔的塔釜再沸器与所述萃取剂净化器的换热面积之比为(5～2):1。
  18. 根据权利要求12-17中任意一项所述的方法，其中，进入所述塔釜再沸器的第一股物流的温度和进入所述萃取剂净化器的第三股物流的温度相差≤5℃优选≤3℃。
  19. 根据权利要求12-18中任意一项所述的方法，其中，所述分离塔的操作条件包括：塔顶气相温度为60～130℃，塔顶温度为30～80℃，压力为0.04～0.40MPaG，塔板数为15～80块。
  20. 根据权利要求12-19中任意一项所述的方法，其中，在含有环氧烷烃和萃取剂的物流中，以摩尔百分比计，所述萃取剂与所述环氧烷烃的比例为(2～15):1，优选为(3～10):1，更优选为(5～7):1。
  21. 根据权利要求12-20中任意一项所述的方法，其中，所述塔釜再沸器为热虹吸式再沸器、釜式再沸器和强制循环式再沸器中的任一种。
  22. 根据权利要求12-21中任意一项所述的方法，其中，所述环氧烷烃为环氧丙烷、环氧丁烷或环氧丁烷的同分异构体，优选所述环氧烷烃为环氧丁烷，更优选所述环氧烷烃为1,2-环氧丁烷。
  23. 一种环氧烷烃生产系统，该系统包括
    1)分离塔，塔釜具有能够将塔釜物流引出所述分离塔的出口；
    2)塔釜再沸器，设置在所述分离塔的下部，对所述分离塔的部分塔釜物料进行再 沸后返回分离塔；
    3)萃取剂净化器，所述萃取剂净化器设置在所述分离塔进料下方，用于对所述分离塔的部分塔釜物料进行净化处理，除去其中沸点高于萃取剂的液相重组分，得到主要为萃取剂的气相或气液混合物轻组分并返回至所述分离塔塔釜。
  24. 根据权利要求23所述的系统，其中，所述萃取剂净化器为再沸器，优选为釜式再沸器。
  25. 根据权利要求24所述的系统，其中，所述分离塔的塔釜再沸器与所述萃取剂净化器的换热面积之比为(5～2):1。
  26. 根据权利要求24或25所述的系统，其中，所述分离塔的塔板数为15～80块，按照物料的流向，所述萃取剂净化器的进料位置位于倒数第0～6块优选第0～4块塔板。
  27. 根据权利要求26所述的系统，其中，所述萃取剂净化器的进料位置比所述塔釜再沸器的进料位置高0～4块塔板。
  28. 根据权利要求23-27中任意一项所述的系统，其中，所述萃取剂净化器通过管道与所述分离塔连通。
  29. 一种环氧烷烃生产系统，该系统包括
    1)萃取精馏塔，用于对含环氧烷烃的粗产品物流进行萃取精馏；
    2)分离塔，用于分离来自萃取精馏塔的塔釜物流并进行分离，塔顶得到主要为环氧烷烃的物流，塔釜得到主要为萃取剂的物流；
    3)塔釜再沸器，设置在所述分离塔的下部，对所述分离塔的部分塔釜物料进行再沸后返回分离塔；
    4)萃取剂净化器，所述萃取剂净化器设置在所述分离塔的进料位置的下方，用于接收所述分离塔的部分塔釜物料并进行净化处理，除去其中沸点高于萃取剂的重组分，得到主要为萃取剂的气相或气液混合物轻组分并返回至所述分离塔。
  30. 根据权利要求29所述的系统，其中，所述萃取剂净化器为再沸器，优选为釜 式再沸器。
  31. 根据权利要求30所述的系统，其中，所述分离塔的塔釜再沸器与所述萃取剂净化器的换热面积之比为(5～2):1。
  32. 根据权利要求30或31所述的系统，其中，所述分离塔的塔板数为15～80块，按照物料的流向，所述萃取剂净化器的进料位置位于第0～6块优选第0～4块塔板。
  33. 根据权利要求32所述的系统，其中，所述萃取剂净化器的进料位置比所述塔釜再沸器的进料位置高0～4块塔板。
  34. 根据权利要求29-33中任意一项所述的系统，其中，所述萃取剂净化器通过管道与所述分离塔连通。
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