CN114181332B - Method and device for reducing fresh methanol consumption and process energy consumption in EVOH production process - Google Patents
Method and device for reducing fresh methanol consumption and process energy consumption in EVOH production process Download PDFInfo
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 title claims abstract description 411
- 229920000219 Ethylene vinyl alcohol Polymers 0.000 title claims abstract description 44
- 239000004715 ethylene vinyl alcohol Substances 0.000 title claims abstract description 43
- UFRKOOWSQGXVKV-UHFFFAOYSA-N ethene;ethenol Chemical compound C=C.OC=C UFRKOOWSQGXVKV-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 40
- 230000008569 process Effects 0.000 title claims abstract description 30
- 238000005265 energy consumption Methods 0.000 title claims abstract description 28
- 238000006136 alcoholysis reaction Methods 0.000 claims abstract description 401
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims abstract description 99
- 239000007788 liquid Substances 0.000 claims abstract description 71
- 239000003054 catalyst Substances 0.000 claims abstract description 58
- 229920000642 polymer Polymers 0.000 claims abstract description 49
- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- 239000000463 material Substances 0.000 claims description 51
- 238000006116 polymerization reaction Methods 0.000 claims description 18
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 8
- 239000005977 Ethylene Substances 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 8
- 239000003513 alkali Substances 0.000 claims description 6
- 230000034659 glycolysis Effects 0.000 claims description 6
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 5
- 239000011344 liquid material Substances 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 2
- 238000004064 recycling Methods 0.000 claims description 2
- 238000009776 industrial production Methods 0.000 abstract description 4
- 239000005038 ethylene vinyl acetate Substances 0.000 description 86
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 77
- 239000007789 gas Substances 0.000 description 77
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 40
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 description 40
- 239000000047 product Substances 0.000 description 23
- 230000004888 barrier function Effects 0.000 description 13
- 238000012805 post-processing Methods 0.000 description 12
- 239000002994 raw material Substances 0.000 description 12
- 229920005989 resin Polymers 0.000 description 10
- 239000011347 resin Substances 0.000 description 10
- 238000007086 side reaction Methods 0.000 description 10
- 238000005809 transesterification reaction Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 230000009471 action Effects 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 6
- 239000004372 Polyvinyl alcohol Substances 0.000 description 5
- 229920002451 polyvinyl alcohol Polymers 0.000 description 5
- 238000010992 reflux Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- 239000007795 chemical reaction product Substances 0.000 description 4
- 238000011143 downstream manufacturing Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000003860 storage Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 4
- 239000004952 Polyamide Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229920002647 polyamide Polymers 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000007127 saponification reaction Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- IMROMDMJAWUWLK-UHFFFAOYSA-N Ethenol Chemical compound OC=C IMROMDMJAWUWLK-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000010528 free radical solution polymerization reaction Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000005033 polyvinylidene chloride Substances 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 1
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000012662 bulk polymerization Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000007720 emulsion polymerization reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- RZXDTJIXPSCHCI-UHFFFAOYSA-N hexa-1,5-diene-2,5-diol Chemical compound OC(=C)CCC(O)=C RZXDTJIXPSCHCI-UHFFFAOYSA-N 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000004807 localization Effects 0.000 description 1
- 150000004702 methyl esters Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 235000021485 packed food Nutrition 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000002954 polymerization reaction product Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000010557 suspension polymerization reaction Methods 0.000 description 1
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 1
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/02—Ethene
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
The invention discloses a production method and a production device for reducing the consumption of fresh methanol and the process energy consumption in the EVOH production process. The method comprises the steps of enabling an EVAC-containing stream and a catalyst stream to be in opposite contact with methanol vapor for carrying out a first alcoholysis reaction, enabling a polymer liquid stream and the catalyst stream obtained by the reaction to be in opposite contact with excessive fresh methanol vapor for carrying out a second alcoholysis reaction to obtain EVOH, wherein most of gas-phase stream obtained after the second alcoholysis reaction is refluxed to serve as a main source of the methanol vapor in the first alcoholysis reaction, and feeding the catalyst stream in each alcoholysis reaction in a mode of adopting at least two different feeding positions. The method adopts double towers to gradually improve the alcoholysis degree, has the advantages of high alcoholysis degree, less fresh methanol consumption, low process energy consumption, less equipment investment, good chromaticity of EOVH products and easy realization of industrial production.
Description
Technical Field
The invention relates to the field of ethylene-vinyl acetate copolymer, in particular to a production method and a device for reducing the fresh methanol consumption and the process energy consumption in the EVOH production process.
Background
Ethylene-vinyl acetate copolymer (EVOH) is a crystalline polymer with chain molecular structure, and is a three-high barrier material which is called as a world three-high barrier material together with polyvinylidene chloride (PVDC) and Polyamide (PA), and the barrier property is about ten thousands times of that of polyethylene and polypropylene, 100 times higher than that of PA, and more than tens of times higher than that of PVDC which is a high barrier material commonly used at present. EVOH resin has high resistance to gas, water and chemical solvents, is an excellent barrier material at present, has great advantages in the aspects of prolonging the storage period of packaged foods, further playing the roles of light weight, difficult breakage and the like of plastic packages, has special important roles in improving the packaging quality, and has good application prospect and wide market.
Because the vinyl alcohol monomer cannot exist stably, the EVOH resin can be obtained only by an alcoholysis reaction of an ethylene-vinyl acetate copolymer (EVAC). The EVAC can be generally formed by polymerization by conventional methods such as emulsion polymerization, solution polymerization, bulk polymerization, and suspension polymerization, and an EVAC polymerization solution for preparing an EVOH resin having high barrier properties is mainly obtained by a solution polymerization method because it is easy to control the composition of EVAC, the degree of polymerization, the degree of branching, and the molecular weight distribution thereof. The properties of EVOH are mainly dependent on the mole fractions of the two comonomers, the gas barrier properties, moisture barrier properties and processability of which vary with the ethylene content, and as the ethylene content increases, the gas barrier properties decrease, the moisture barrier properties improve and the resin is easier to process. When the ethylene content is more than 50%, the gas barrier property is seriously impaired, and thus the molar content of ethylene in EVOH is usually 20 to 45% and the molar content of vinyl alcohol is usually 55 to 80%, which combines the characteristics of the gas barrier property of polyvinyl alcohol (PVA) and the processability of polyethylene. EVOH can be regarded as a PVA modifier, and the production process is similar to that of PVA, so that EVOH manufacturers in the world are leading PVA manufacturers.
At present, only a few countries such as America and Japan exist in the world for production, the production technology is mainly monopolized by Japanese colali company (trademark EVAL) and Japanese synthetic chemical industry company (trademark Soarnol), the production is almost blank in China, the product mainly depends on import, and the cost is high, so that the localization of the EVOH resin is realized, the application range of the EVOH resin in the field of barrier materials is expanded, and the method has important social and economic significance for development, research and application of the EVOH resin.
The alcoholysis process of EVOH mainly occurs in an alcoholysis tower, and the EVAC polymerization solution from a polymerization unit and methanol vapor undergo alcoholysis reaction under the action of an alkaline catalyst, wherein the reaction is a reversible equilibrium reaction. Because both the reaction raw material and the product contain polymer, the alcoholysis tower can not be provided with a reboiler, the heat required in the reaction process is mainly provided by virtue of a large excess of methanol steam, and if fresh methanol is used as the reaction raw material, the consumption of the fresh methanol in the reaction process is large, and the subsequent recovery cost of the methanol is high. In addition, the alcoholysis process generally involves three types of reactions: transesterification, saponification, and side reactions, in which transesterification is the main reaction, the specific reaction equations are shown below. The transesterification reaction process can generate a side reaction product methyl acetate, the side reaction is accelerated gradually along with the increase of the amount of the methyl acetate, and the consumption of the alkaline catalyst is increased, so that the addition amount and the addition mode of the alkaline catalyst can have important influence on the alcoholysis process.
Transesterification:
saponification reaction:
side reaction:
CH 3 COOCH 3 +NaOH→CH 3 OH+CH 3 COONa。
CN204602161U discloses an alcoholysis reaction system for use in the production process of EVOH, which comprises an alcoholysis device connected with an alcohol feed line, a resin feed line, a catalyst feed line, a gas inlet line, an EVOH discharge line and a steam discharge line at the same time, and a metering pump, a heat exchanger, a pressure stabilizing valve, a condensate tank and an electric heater. When alcoholysis is carried out in production, liquid alcohol is continuously added into the lower part of the alcoholysis device from an alcohol feeding pipeline through a first metering pump, and meanwhile, inert gases such as air, nitrogen, methane or helium and the like are added through a gas inlet pipeline, and the pressure is controlled to be 0.2-1 Mpa; continuously adding a certain amount of catalysts such as NaOH or KOH alcohol solution and the like into the upper part of the alcoholysis device from a catalyst feeding pipeline through a second metering pump, and simultaneously continuously adding polymerization solution obtained by copolymerizing ethylene and vinyl acetate into the upper part of the alcoholysis device through a third metering pump; under the action of a catalyst, the rising pure steam and resin carry out alcoholysis reaction, the generated EVOH resin falls to the bottom of an alcoholysis device under the action of gravity, the generated methyl ester is condensed into liquid from the top of the alcoholysis device to a heat exchanger, the liquid is stored in a condensate tank, and the noncondensable gas is discharged out of the system through a pressure stabilizing valve.
CN203269838U discloses an alcoholysis production system of ethylene-vinyl alcohol, comprising a rectifying tower, a lateral line extraction tank connected with the side surface of the rectifying tower, wherein the extraction tank is connected with an electric heating sleeve; the catalyst storage tank is connected with a catalyst feeding pump which is connected with the top of the rectifying tower; the polymerization liquid storage tank is connected with a polymerization liquid feeding pump which is connected with the top of the rectifying tower; the methanol storage tank is connected with a methanol feed pump which is connected with the bottom of the rectifying tower; the top of the rectifying tower is provided with a rectifying outlet.
CN106146720a discloses an alcoholysis method in the preparation process of ethylene-vinyl alcohol copolymer, comprising the following steps: (1) purification and blending of alcoholysis raw materials: the alcoholysis raw material is directly from the preparation process of EVOH, and is a polymerization reaction product prepared by polymerization reaction of ethylene and vinyl acetate; heating the alcoholysis raw material to 70-75 ℃, adding methanol for solvent replacement to ensure that the VAC content in the alcoholysis raw material is 0.1-3 wt% and the water content is 0.05-0.3 wt%; adding methanol for blending to obtain ethylene-vinyl acetate copolymer solution with the content of 5-50wt%; (2) preparation of a catalyst solution: preparing catalyst solution with 3-10wt% of catalyst and methanol, stirring to dissolve the catalyst solution fully; wherein the catalyst is selected from sodium hydroxide, potassium hydroxide, tetramethyl ammonium hydroxide or tetraethyl ammonium hydroxide, or mixed alkali consisting of tetramethyl ammonium hydroxide and sodium hydroxide in a molar ratio of 4.5:1-14:1; (3) alcoholysis reaction: in the alcoholysis reaction, controlling the total consumption of the catalyst solution and the consumption of the ethylene-vinyl acetate copolymer solution, wherein the weight ratio is 1-5:10; during alcoholysis, under the stirring state of stirring rotation speed of 150-200 rpm, firstly uniformly mixing 100 parts by weight of ethylene-vinyl acetate copolymer solution and 5-25 parts by weight of catalyst solution, pre-reacting for 10-30 min at normal temperature to 40 ℃, then heating to 65-85 ℃, adding the rest catalyst solution, mixing, continuing to react, continuously heating and azeotropically taking out byproducts, reacting for 1-8 hours until alcoholysis is complete, and finally squeezing and drying to obtain the EVOH.
Disclosure of Invention
The invention provides a production method and a device for reducing the fresh methanol consumption and the process energy consumption in the EVOH production process, which can be used for guiding and easily realizing industrial production.
The invention relates to a production method and a device for reducing the consumption of fresh methanol and process energy consumption in the EVOH production process, which can be used in the alcoholysis process of the EVOH production to realize continuous and efficient alcoholysis reaction, and has the advantages of simple flow, high alcoholysis degree, less fresh methanol consumption, low process energy consumption, less equipment investment, good EOVH product chromaticity and easy realization of industrial production.
The invention aims to provide a production method for reducing the consumption of fresh methanol and the process energy consumption in the EVAC production process, which comprises the steps of carrying out first alcoholysis reaction on an EVAC-containing material flow and a catalyst material flow which are in opposite contact with methanol vapor, and carrying out second alcoholysis reaction on the polymer material flow and the catalyst material flow which are obtained by the reaction and the excessive fresh methanol vapor which are in opposite contact with each other, wherein most of gas phase material flow obtained after the second alcoholysis reaction is refluxed to be used as a main source of the methanol vapor in the first alcoholysis reaction, and the catalyst material flow in each alcoholysis reaction is fed by adopting at least two modes with different feeding positions.
In the technical scheme of the invention, the EVAC-containing material flow and the catalyst material flow are contacted with methanol steam in opposite directions to carry out a first alcoholysis reaction to obtain a polymerization solution which is not completely alcoholyzed, and then the polymerization solution material flow is contacted with the catalyst material flow and fresh methanol steam in opposite directions to carry out a second alcoholysis reaction until the alcoholysis degree of the obtained EVOH reaches more than 99 percent.
Preferably, the technical scheme adopted by the invention comprises the following steps:
1) Feeding the EVAC-containing material flow from the upper part of an alcoholysis tower, feeding the catalyst material flow from at least the upper part and the middle part of the alcoholysis tower, blowing methanol steam into the bottom of the alcoholysis tower, and performing a first alcoholysis reaction;
2) The gas phase material flow obtained by the first alcoholysis reaction is discharged from the top of the first alcoholysis tower as the top gas of the first alcoholysis tower, and the polymer liquid material flow which is not completely alcoholyzed is discharged as the bottom liquid of the first alcoholysis tower;
3) The first tower bottom liquid of the alcoholysis is sent to the upper part of the second tower of the alcoholysis, the catalyst material flows are respectively sent from the upper part of the second tower of the alcoholysis and the middle part of the second tower of the alcoholysis, and excessive fresh methanol steam is blown into the bottom of the second tower of the alcoholysis to generate a second alcoholysis reaction;
4) The gas phase material flow obtained by the second glycolysis reaction is discharged from the top of the second glycolysis tower as the top gas, and most of the gas phase material flow is introduced into the bottom of the first glycolysis tower to be used as a main source of methanol steam; and discharging the bottom liquid of the alcoholysis second tower to obtain the EVOH.
In the technical scheme of the invention, the material flow containing EVAC is EVAC polymerization liquid after ethylene and vinyl acetate are removed, and the material flow mainly contains EVAC and methanol.
In the technical scheme of the invention, the EVAC content in the EVAC-containing material flow is more than or equal to 20wt%, preferably more than or equal to 25wt%.
In the technical scheme of the invention, the alkaline catalyst is a methanol solution of alkali; the concentration of the alkali solution is preferably 2 to 20wt%, more preferably 5 to 10wt%.
In the technical scheme of the invention, the alcoholysis degree of the EVOH obtained by the second alcoholysis reaction is more than or equal to 99 percent.
In the technical scheme of the invention, in the step 1), the pressure of the EVAC-containing material flow fed into the alcoholysis one tower is 0.3-0.9 MPaG, preferably 0.5-0.8 MPaG;
in the technical scheme of the invention, the pressure of the bottom of the alcoholysis one-tower is 0.3-0.8 MPaG, preferably 0.3-0.6 MPaG;
in the technical scheme of the invention, the top pressure of the alcoholysis one-tower is 0.2-0.7 MPaG, preferably 0.3-0.6 MPaG.
In the technical scheme of the invention, in the step 3), the pressure of the bottom of the alcoholysis two-tower is 0.3-0.8 MPaG, preferably 0.3-0.6 MPaG.
In the technical scheme of the invention, the top pressure of the alcoholysis two-tower is 0.2-0.7 MPaG, preferably 0.3-0.6 MPaG.
In the technical scheme of the invention, more preferably, the pressure of the alcoholysis second tower is higher than that of the alcoholysis first tower.
In the technical scheme of the invention, in the step 1), the methanol steam for the first-tower alcoholysis reaction mainly comes from the second-tower top gas of alcoholysis.
In the technical scheme of the invention, the amount of the fresh methanol supplemented by the alcoholysis tower accounts for 0-10wt%, preferably 0-5wt% of the total methanol of the alcoholysis tower.
In the technical scheme of the invention, the catalyst material flows are added into the alcoholysis tower in different feeding positions.
According to a preferred embodiment of the invention, the catalyst streams enter from the upper and middle parts of the first alcoholysis column, respectively, and the catalyst streams enter from the upper and middle parts of the second alcoholysis column, respectively.
In the technical scheme of the invention, a material flow containing reaction byproducts of methyl acetate and excessive methanol steam is discharged from the top of the alcoholysis one tower, and is condensed to obtain a tower top non-condensable gas material flow and a tower top condensate material flow, and the condensate material flow is completely sent to a downstream process or partially reflowed to return to the alcoholysis one tower; and (3) discharging the top gas containing a small amount of methyl acetate and a large amount of methanol vapor from the top of the alcoholysis secondary tower, sending most of the top gas into the bottom of the alcoholysis primary tower to serve as gas-phase methanol feed, merging the rest of the top gas with the top noncondensable gas stream of the alcoholysis primary tower, condensing to obtain a condensed liquid stream and a noncondensable gas stream, and sending all the condensed liquid stream into a downstream process or partially refluxing and returning to the alcoholysis secondary tower.
According to a preferred embodiment of the invention, the production process flow is as follows:
1) And conveying the EVAC polymer liquid stream from the polymerization unit to an alcoholysis tower to carry out alcoholysis under alkaline conditions, outputting the polymer liquid which is not completely alcoholyzed by the bottom of the alcoholysis tower, and conveying the polymer liquid to an alcoholysis tower to continue alcoholysis until the alcoholysis degree reaches more than 99%.
2) The methanol vapor at the bottom of the alcoholysis tower mainly comes from the top gas of the alcoholysis tower, and can be not supplemented or only supplemented with a small amount of fresh methanol vapor.
3) Most of the gas at the top of the alcoholysis secondary tower is introduced into the bottom of the alcoholysis primary tower to be used as a raw material of methanol for alcoholysis and a heat source of the alcoholysis primary tower.
4) The alkaline catalyst materials are respectively fed from the upper part and the middle part of the first alcoholysis tower, and the alkaline catalyst materials are respectively fed from the upper part and the middle part of the second alcoholysis tower.
It is a second object of the present invention to provide an apparatus for reducing the amount of fresh methanol and the process energy consumption in the production of EVOH, for carrying out the above-mentioned method, comprising:
alcoholysis-tower: configured to receive the EVAC-containing stream in an upper portion, the catalyst stream in upper and middle portions, the methanol vapor stream in a bottom portion, the alcoholysis first column overhead gas stream in a top portion, and the alcoholysis first column bottoms stream in a bottom portion;
alcoholysis second tower: the device is configured to receive an alcoholysis first-tower bottom liquid stream at the upper part, receive catalyst streams at the upper part and the middle part, receive a methanol steam stream at the bottom part, discharge an alcoholysis second-tower top gas stream at the top part of the tower, and discharge an alcoholysis second-tower bottom liquid stream at the bottom part of the tower;
alcoholysis-overhead condenser: configured to receive an alcoholysis column overhead gas stream, discharge condensate and noncondensable gas;
alcoholysis second overhead condenser: the device is configured to receive an alcoholysis second tower top gas stream and noncondensable gas of an alcoholysis first tower condenser, and discharge condensate and noncondensable gas;
the apparatus is configured with a conduit for recycling the alcoholysis second column overhead gas stream to the bottom of the alcoholysis first column.
In the technical scheme of the invention, the alcoholysis degree of the bottom liquid discharged from the bottom of the alcoholysis second tower is more than 99%.
In the technical scheme of the invention, 1-4 m empty trays, preferably 2-3 m, are reserved at the upper sections of the feeding positions of the first alcoholysis tower and the second alcoholysis tower.
In the present invention, both EVAC and EVOH polymers have relatively high viscosities, and in particular, the viscosities increase exponentially with decreasing temperature. Three types of reactions generally occur during alcoholysis: transesterification, saponification, and side reactions, wherein transesterification is the primary reaction. The transesterification reaction process can generate a side reaction product methyl acetate, the side reaction is accelerated gradually along with the increase of the amount of the side reaction product methyl acetate, and the consumption of the alkaline catalyst is increased, so that the addition amount and the addition mode of the alkaline catalyst can have important influence on the alcoholysis process. In addition, the alcoholysis process of EVAC mainly occurs in an alcoholysis tower, and the EVAC polymerization solution from the polymerization unit and countercurrent methanol vapor undergo alcoholysis reaction under the action of an alkaline catalyst, and the reaction is a reversible equilibrium reaction, so that measures are required to fully remove the small molecular byproduct methyl acetate generated by the transesterification reaction to promote the reaction to move rightward in order to obtain an EVOH product with high alcoholysis degree. It is reported that the alcoholysis reaction is a quick-after-slow reaction, and the alcoholysis reaction is rapidly carried out after the addition of the alkaline catalyst, so that a large amount of small molecule byproduct methyl acetate is generated, and methyl acetate which is not removed at high temperature is easily oxidized into aldehyde substances which are easy to color, so that the color of the final EVOH product is yellow, the appearance is poor, smell exists and the like. Because both the reaction raw material and the product contain polymer, the alcoholysis tower cannot be provided with a reboiler, the heat required in the reaction process is mainly provided by means of a large excess of methanol steam, and if fresh methanol is used as the reaction raw material, the consumption of the fresh methanol in the reaction process is large, and the subsequent recovery cost of the methanol is high. According to research, in the alcoholysis reaction process adopting double-tower cascade, the transesterification reaction in the alcoholysis second tower is very small, the content of the side reaction product methyl acetate in the tower top gas is very small, and the main component is methanol steam. Therefore, the invention uses the fresh methanol as the reaction raw material only in the second alcoholysis tower, and the methanol steam of the reaction raw material of the first alcoholysis tower mainly comes from the second alcoholysis tower top gas, and only a small amount of fresh methanol is supplemented; secondly, the alkaline catalyst is divided into different positions and added into the alcoholysis tower, so that the distribution of the catalyst in the alcoholysis tower is improved, the alcoholysis reaction efficiency is increased, and the occurrence of side reaction is reduced. The use level of fresh methanol can be obviously reduced by about 50% by adopting the design of the invention; on the other hand, the amount of fresh methanol vapor in the first alcoholysis tower is greatly reduced, and most of the gas at the top of the second alcoholysis tower is directly sent to the first alcoholysis tower to supplement heat sources and raw materials without condensation, so that the process energy consumption of the alcoholysis process is also obviously reduced.
The method adopts double towers to gradually improve the alcoholysis degree, has the advantages of high alcoholysis degree, less consumption of fresh methanol, low process energy consumption, less equipment investment, good chromaticity of EOVH products and easy realization of industrial production.
All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference in their entirety. Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art. In case of conflict, the present specification, definitions, will control.
When the specification derives materials, substances, methods, steps, devices, or elements and the like in the word "known to those skilled in the art," "prior art," or similar words, the word "derived" is intended to cover those commonly used in the art at the time of this application, but also includes those which are not yet commonly used, but which will become known in the art to be suitable for similar purposes.
In the context of this specification, any matters or matters not mentioned are directly applicable to those known in the art without modification except as explicitly stated. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or ideas formed thereby are all considered as part of the original disclosure or original description of the invention, and should not be considered as new matters not disclosed or contemplated herein unless the combination is obviously unreasonable by those skilled in the art.
The present invention is further illustrated by, but not limited to, the following examples.
Drawings
FIG. 1 is a schematic flow chart of a method for reducing fresh methanol consumption and process energy consumption in EVOH production according to an embodiment of the invention.
Fig. 1 is a marked illustration:
a-alcoholysis tower;
b-alcoholysis second tower;
c-alcoholysis an overhead condenser;
d-alcoholysis of a second tower top condenser;
1-basic catalyst solution I;
2-EVAC-containing stream;
3-fresh methanol vapor I;
4-alcoholysis of tower bottom liquid of the first tower;
5-basic catalyst solution II;
6-alcoholysis of a tower top gas;
7-reflux of tower top gas of the alcoholysis second tower;
8-alcoholysis of the tower top gas of the second tower;
9-merging top gas by an alcoholysis tower;
10-alcoholysis of non-condensable gas in the top gas of a first tower;
11-alcoholysis of tower top gas condensate;
12 alcoholysis of non-condensable gas in the top gas of the second tower;
13-alcoholysis of tower top gas condensate of the second tower;
14-fresh methanol vapor II;
15-alcoholysis of the second tower bottom liquid.
In fig. 1, a stream 2 containing EVAC enters an alcoholysis tower a from the upper part, and at the same time, a stream 1 of an alkaline catalyst solution I is added from the alcoholysis tower a, the stream 1 is divided into two streams, and enters the alcoholysis tower a from the upper part and the middle part of the alcoholysis tower a respectively, and a stream 3 of fresh methanol vapor I is not introduced or is introduced in a small amount from the bottom of the alcoholysis tower a; under the action of an alkaline catalyst, carrying out an alcoholysis reaction on a material flow containing EVAC and methanol in an alcoholysis tower A, discharging an alcoholysis tower overhead gas material flow 6 containing reaction byproducts of methyl acetate and excessive methanol steam from the top of the tower, condensing the material flow 6 by an alcoholysis tower overhead condenser C to obtain an alcoholysis tower overhead gas condensate material flow 11 and an alcoholysis tower overhead gas noncondensable gas material flow 10, and sending the material flow 11 into a downstream process or partially refluxing and returning to the alcoholysis tower A; the bottom of the first alcoholysis tower A is an alcoholysis tower kettle liquid material 4 mainly containing EVOH and incompletely alcoholyzed EVAC, the material flow 4 is sent to the upper part of a second alcoholysis tower B to be used as a feed, meanwhile, a material flow 5 of alkaline catalyst solution II is added from the second alcoholysis tower B, the material flow 5 is divided into two streams, the two streams enter the tower from the upper part and the middle part of the second alcoholysis tower B, and a material flow 14 of excessive fresh methanol vapor II is added to the bottom of the second alcoholysis tower B; the top of the alcoholysis secondary tower is provided with a tower top gas containing a small amount of methyl acetate and a large amount of methanol vapor, the tower top gas is divided into two streams, a small stream of alcoholysis secondary tower top gas material 8 and an alcoholysis primary tower top gas noncondensable gas stream 10 are combined into an alcoholysis tower combined top gas stream 9, the stream 9 is condensed by an alcoholysis secondary tower top condenser D to obtain an alcoholysis secondary tower top gas noncondensable gas 12 and an alcoholysis secondary tower top gas condensate stream 13, the stream 13 is sent to a downstream process or partially reflowed to return to the alcoholysis secondary tower B, and the other stream of alcoholysis secondary tower top gas reflow stream 7 is sent to the bottom of the alcoholysis primary tower A to be used as gas-phase methanol feed; and discharging the alcoholysis second-tower kettle liquid stream 15 of the alcoholysis second-tower B for post-treatment, and washing and drying to obtain an EVOH product.
Fig. 2 is a flow chart showing a production method of producing EVOH by alcoholysis of a polymerization solution of EVAC in comparative example.
Fig. 2 label description:
s1-alcoholysis of a tower;
s2-alcoholysis second tower;
s3-alcoholysis of a tower top condenser;
s4-alcoholysis of a second tower top condenser;
101-basic catalyst solution I;
102-an EVAC-containing stream;
103-alcoholysis of a tower top gas;
104-alcoholysis of tower bottom liquid of the first tower;
105-fresh methanol vapor I;
106-basic catalyst solution II;
107-fresh methanol vapor II;
108-alcoholysis of the tower top gas of the second tower;
109-alcoholysis of second tower bottoms;
110-alcoholysis of non-condensable gas in the top gas of the second tower;
111-alcoholysis of tower top gas condensate of the second tower;
112-alcoholysis of non-condensable gas in the top gas of the first tower;
113-alcoholysis of tower top gas condensate.
In fig. 2, the EVAC-containing stream 102 enters the alcoholysis primary tower S1 from the upper part, and at the same time, a stream 101 of the basic catalyst solution I is added from the upper part of the alcoholysis primary tower S1, and a large amount of stream 105 of fresh methanol vapor I is introduced into the bottom of the alcoholysis primary tower S1; under the action of an alkaline catalyst, carrying out an alcoholysis reaction on the polymerization liquid EVAC and methanol in a tower S1, discharging an alcoholysis tower top gas stream 103 containing reaction byproducts of methyl acetate and excessive fresh methanol steam from the top of the tower, condensing the stream 103 by an alcoholysis tower top condenser S3 to obtain an alcoholysis tower top gas condensate 113 and an alcoholysis tower top gas noncondensable gas 112, and discharging the alcoholysis tower top gas condensate stream 113 into a downstream system or refluxing a part of the alcoholysis tower top gas condensate stream back to the alcoholysis tower S1; the bottom of the first alcoholysis tower S1 is an alcoholysis first tower bottom liquid stream 104 mainly containing EVOH and incompletely alcoholyzed EVAC, the stream 104 is sent to the upper part of a second alcoholysis tower S2 to be used as a feed, and meanwhile, a stream 106 of alkaline catalyst solution II is added from the upper part of the second alcoholysis tower S2, and a stream 107 of excessive fresh methanol vapor II is added to the bottom of the second alcoholysis tower S2; the top of the alcoholysis secondary tower is provided with a top gas stream 108 containing a small amount of methyl acetate and a large amount of methanol steam, the stream 108 is condensed by an alcoholysis secondary tower top condenser S4 to obtain an alcoholysis secondary tower top gas condensate stream 111 and an alcoholysis secondary tower top gas noncondensable gas stream 110, and the alcoholysis secondary tower top gas condensate stream 111 can be discharged and sent to a downstream system or a part of reflux returns to the alcoholysis secondary tower S2; and discharging the alcoholysis second tower kettle liquid stream 109 for post-treatment, and washing and drying to obtain an EVOH product.
Detailed Description
The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention.
The technical scheme of the invention is adopted by taking 10000kg/h of product stream as a reference, and the description is given by examples.
[ example 1 ]
The process flow of this example is shown in FIG. 1, wherein the upper sections of the feed locations of the first and second alcoholysis columns leave a 2.5m empty tray.
The polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 20t/h, the flow rate of the stream 7 is 9.5t/h, the alcoholysis degree of the EVAC polymer liquid of the first alcoholysis tower can reach 98.45%, the methyl acetate content in the tower kettle stream 4 is 1960ppm, the alcoholysis degree of the EVAC polymer liquid of the second alcoholysis tower can reach 99.13%, the methyl acetate content in the tower kettle stream 15 is 95ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 7128.38Kw.
[ example 2 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 22t/h, the flow rate of the stream 7 is 11.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.47%, the methyl acetate content in the stream 4 in the tower kettle is 1980ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.22%, the methyl acetate content in the stream 15 in the tower kettle is 88ppm, and the product color is whiter after post-processing. The total energy consumption of fresh methanol was 7841.22Kw.
[ example 3 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 25t/h, the flow rate of the stream 7 is 14.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.48%, the methyl acetate content in the tower kettle stream 4 is 2032ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.34%, the methyl acetate content in the tower kettle stream 15 is 76ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 8910.48Kw.
[ example 4 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 28t/h, the flow rate of the stream 7 is 17.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.50%, the methyl acetate content in the tower kettle stream 4 is 2056ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.43%, the methyl acetate content in the tower kettle stream 15 is 62ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 9979.74Kw.
[ example 5 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 30t/h, the flow rate of the stream 7 is 19.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.52%, the methyl acetate content in the tower kettle stream 4 is 2050ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.54%, the methyl acetate content in the tower kettle stream 15 is 56ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 10692.6Kw.
[ example 6 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 0t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 32t/h, the flow rate of the stream 7 is 21.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.55%, the methyl acetate content in the tower kettle stream 4 is 2090ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.64%, the methyl acetate content in the tower kettle stream 15 is 40ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 11405.4Kw.
[ example 7 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.37MPaG, and the pressure of the top of the alcoholysis one-tower is 0.35MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.55MPaG, and the pressure of the top of the alcoholysis second tower is 0.50MPaG.
And the top condensate of the first alcoholysis tower and the second alcoholysis tower is not refluxed.
The consumption of fresh methanol steam flow 3 of the first alcoholysis tower is 0.5t/h, the consumption of fresh methanol steam flow 14 of the second alcoholysis tower is 30t/h, the flow rate of the flow 7 is 19.5t/h, the alcoholysis degree of the EVAC polymer liquid of the first alcoholysis tower can reach 98.56%, the methyl acetate content of the tower kettle flow 4 is 2068ppm, the alcoholysis degree of the EVAC polymer liquid of the second alcoholysis tower can reach 99.60%, the methyl acetate content of the tower kettle flow 15 is 42ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol is 10860.60Kw.
[ example 8 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.37MPaG, and the pressure of the top of the alcoholysis one-tower is 0.35MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 1t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 30t/h, the flow rate of the stream 7 is 19.5t/h, the alcoholysis degree of the EVAC polymer liquid of the first alcoholysis tower can reach 98.63%, the methyl acetate content of the tower kettle stream 4 is 2085ppm, the alcoholysis degree of the EVAC polymer liquid of the second alcoholysis tower can reach 99.65%, the methyl acetate content of the tower kettle stream 15 is 36ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 11049.00Kw.
[ example 9 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.42MPaG, and the pressure of the top of the alcoholysis one-tower is 0.40MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.55MPaG, and the pressure of the top of the alcoholysis second tower is 0.50MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 1t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 30t/h, the flow rate of the stream 7 is 19.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.68%, the methyl acetate content in the tower kettle stream 4 is 2110ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.68%, the methyl acetate content in the tower kettle stream 15 is 32ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 11038.6Kw.
[ example 10 ]
Embodiments are the same as example 1 except that the polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 4wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.37MPaG, and the pressure of the top of the alcoholysis one-tower is 0.35MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The fresh methanol steam stream 3 consumed by the first alcoholysis tower is 1t/h, the fresh methanol steam stream 14 consumed by the second alcoholysis tower is 30t/h, the flow rate of the stream 7 is 19.5t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.03%, the methyl acetate content in the stream 4 in the tower kettle is 2032ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.18%, the methyl acetate content in the stream 15 in the tower kettle is 40ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 11049.00Kw.
[ comparative example 1 ]
The process flow of this comparative example is shown in FIG. 1.
The polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 0.5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.26MPaG, and the pressure of the top of the alcoholysis one-tower is 0.24MPaG.
The pressure of the bottom of the alcoholysis two-tower is 0.28MPaG, and the pressure of the top of the alcoholysis two-tower is 0.26MPaG.
The consumption of fresh methanol vapor stream 105 of the first alcoholysis tower is 0t/h, the consumption of fresh methanol vapor stream 107 of the second alcoholysis tower is 30t/h, the alcoholysis degree of the EVAC polymer liquid of the first alcoholysis tower can reach 76.51%, the methyl acetate content of the tower bottom stream 104 can reach 1750ppm, the alcoholysis degree of the EVAC polymer liquid of the second alcoholysis tower can reach 80.20%, and the methyl acetate content of the tower bottom stream 109 can reach 500ppm. The alcoholysis degree of the product is too low, the tower blocking phenomenon is easy to occur, and the total energy consumption of fresh methanol is 10500.50Kw.
[ comparative example 2 ]
The process flow of this comparative example is shown in FIG. 2, wherein a portion of the overhead of the alcoholysis first column and the alcoholysis second column are refluxed.
The polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
The consumption of the fresh methanol vapor stream 105 of the first alcoholysis tower is 14.5t/h, the consumption of the fresh methanol vapor stream 107 of the second alcoholysis tower is 20t/h, the alcoholysis degree of the EVAC polymer liquid of the first alcoholysis tower can reach 98.51 percent, the content of methyl acetate in the tower bottom stream 104 can reach 2050ppm, the alcoholysis degree of the EVAC polymer liquid of the second alcoholysis tower can reach 99.37 percent, the content of methyl acetate in the tower bottom stream 109 can reach 62ppm, and the color of the product after post-processing is whiter. The total energy consumption of fresh methanol was 12296.5Kw.
[ comparative example 3 ]
The process flow of this comparative example is shown in FIG. 2, wherein the top condensate of the first and second alcoholysis columns is not refluxed.
The polymer liquid stream of EVAC comprises, in weight percent: 70wt% methanol, 30wt% EVAC copolymer, at a pressure of 0.6MPaG.
The concentration of the sodium hydroxide lye is 5wt percent.
The pressure of the bottom of the alcoholysis one-tower is 0.32MPaG, and the pressure of the top of the alcoholysis one-tower is 0.30MPaG.
The pressure of the bottom of the alcoholysis second tower is 0.57MPaG, and the pressure of the top of the alcoholysis second tower is 0.55MPaG.
And the top condensate of the first alcoholysis tower and the second alcoholysis tower is not refluxed.
The consumption of fresh methanol vapor stream 105 in the first alcoholysis tower is 19.5t/h, the consumption of fresh methanol vapor stream 107 in the second alcoholysis tower is 20t/h, the alcoholysis degree of the EVAC polymer liquid in the first alcoholysis tower can reach 98.56%, the content of methyl acetate in the tower bottom stream 104 can reach 2067ppm, the alcoholysis degree of the EVAC polymer liquid in the second alcoholysis tower can reach 99.57%, the content of methyl acetate in the tower bottom stream 109 can reach 60ppm, and the color of the product after post-processing is white. The total energy consumption of fresh methanol was 14078.60Kw.
Claims (16)
1. A production method for reducing the consumption of fresh methanol and process energy consumption in the EVOH production process comprises the following steps: 1) Feeding a material flow containing EVAC from the upper part of an alcoholysis first tower, feeding a catalyst material flow from at least the upper part and the middle part of the alcoholysis first tower respectively, blowing methanol steam into the bottom of the alcoholysis first tower, and performing a first alcoholysis reaction, wherein the amount of fresh methanol supplemented by the alcoholysis first tower accounts for 0-10wt% of the total methanol amount of the alcoholysis first tower;
2) The gas phase material flow obtained by the first alcoholysis reaction is discharged from the top of the first alcoholysis tower as the top gas of the first alcoholysis tower, and the polymer liquid material flow which is not completely alcoholyzed is discharged as the bottom liquid of the first alcoholysis tower;
3) The bottom liquid of the first alcoholysis tower is sent to the upper part of the second alcoholysis tower, the catalyst material flows are respectively sent from the upper part and the middle part of the second alcoholysis tower, and excessive fresh methanol steam is blown into the bottom of the second alcoholysis tower to carry out a second alcoholysis reaction;
4) The gas phase material flow obtained by the second glycolysis reaction is discharged from the top of the second glycolysis tower as the top gas, and most of the gas phase material flow is introduced into the bottom of the first glycolysis tower to be used as a main source of methanol steam; and discharging the bottom liquid of the alcoholysis second tower to obtain the EVOH.
2. The production method according to claim 1, characterized in that:
in the step 1), the amount of the fresh methanol supplemented by the alcoholysis tower accounts for 0-5wt% of the total methanol amount of the alcoholysis tower.
3. The production method according to claim 1, characterized in that:
in the step 1), the pressure of the EVAC-containing material flow fed into the alcoholysis tower is 0.3-0.9 MPaG; and/or the number of the groups of groups,
the pressure of the tower bottom of the alcoholysis tower is 0.3-0.8 MPaG; and/or the number of the groups of groups,
the tower top pressure of the alcoholysis tower is 0.2-0.7 MPaG.
4. A production method according to claim 3, characterized in that:
in the step 1), the pressure of the EVAC-containing material flow fed into an alcoholysis tower is 0.5-0.8 MPaG; and/or the number of the groups of groups,
the pressure of the tower bottom of the alcoholysis tower is 0.3-0.6 MPaG; and/or the number of the groups of groups,
the tower top pressure of the alcoholysis tower is 0.3-0.6 MPaG.
5. The production method according to claim 1, characterized in that:
in the step 3), the pressure of the bottom of the alcoholysis two-tower is 0.3-0.8 MPaG; and/or the number of the groups of groups,
the top pressure of the alcoholysis second tower is 0.2-0.7 MPaG.
6. The production method according to claim 5, wherein:
in the step 3), the pressure of the bottom of the alcoholysis two-tower is 0.3-0.6 MPaG; and/or the number of the groups of groups,
the top pressure of the alcoholysis second tower is 0.3-0.6 MPaG.
7. The production method according to claim 5, wherein:
the pressure of the alcoholysis second tower is larger than that of the alcoholysis first tower.
8. The production method according to any one of claims 1 to 7, characterized in that:
the EVAC-containing stream is an EVAC polymerization liquid after removing ethylene and vinyl acetate, and the stream comprises EVAC and methanol.
9. The production method according to claim 8, characterized in that:
the EVAC content in the EVAC-containing stream is greater than or equal to 20wt%.
10. The production method according to claim 9, characterized in that:
the EVAC content in the EVAC-containing stream is greater than or equal to 25wt%.
11. The production method according to any one of claims 1 to 7, characterized in that:
the catalyst is a methanol solution of alkali;
the concentration of the alkali solution is 2-20wt%.
12. The production method according to claim 11, characterized in that:
the concentration of the alkali solution is 5-10wt%.
13. The production method according to any one of claims 1 to 7, characterized in that:
the alcoholysis degree of the EVOH obtained by the second alcoholysis reaction is more than or equal to 99 percent.
14. An apparatus for reducing fresh methanol consumption and process energy consumption in the production of EVOH for carrying out the method of any one of claims 1 to 13, comprising:
alcoholysis-tower: the catalyst is configured to receive an EVAC-containing stream at the upper part, a catalyst stream at the upper part and a catalyst stream at the middle part, a methanol steam stream at the bottom part, an alcoholysis tower top gas stream at the top part of the tower, and an alcoholysis tower bottom liquid stream at the bottom part of the tower;
alcoholysis second tower: the device is configured to receive an alcoholysis first-tower bottom liquid stream at the upper part, receive catalyst streams at the upper part and the middle part, receive a methanol steam stream at the bottom part, discharge an alcoholysis second-tower top gas stream at the top part of the tower, and discharge an alcoholysis second-tower bottom liquid stream at the bottom part of the tower;
alcoholysis-overhead condenser: configured to receive an alcoholysis column overhead gas stream, discharge condensate and noncondensable gas;
alcoholysis second overhead condenser: the device is configured to receive an alcoholysis two-tower overhead gas stream and an alcoholysis one-tower noncondensable gas, and discharge condensate and noncondensable gas;
the apparatus is configured with a conduit for recycling the alcoholysis second column overhead gas stream to the bottom of the alcoholysis first column.
15. The apparatus according to claim 14, wherein:
and an empty tray of 1-4 m is reserved at the upper sections of the feeding positions of the first alcoholysis tower and the second alcoholysis tower.
16. The apparatus according to claim 15, wherein:
and an empty tray with the thickness of 2-3 m is reserved at the upper sections of the feeding positions of the first alcoholysis tower and the second alcoholysis tower.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE728742A (en) * | 1968-02-23 | 1969-08-21 | ||
| US3985719A (en) * | 1974-10-21 | 1976-10-12 | National Distillers And Chemical Corporation | Process for the controlled alcoholysis of ethylene-vinyl ester interpolymers |
| CA2399167A1 (en) * | 2001-09-03 | 2003-03-03 | Kuraray Co., Ltd. | Ethylene-vinyl alcohol copolymer composition, and powdery coating composition comprising it |
| CN101709100A (en) * | 2009-12-18 | 2010-05-19 | 浙江大学 | Method for preparing polyethylene-vinyl alcohol copolymer by catalysis-free hydrolysis of polyethylene vinyl acetate in near-critical water |
| CN102703223A (en) * | 2012-05-31 | 2012-10-03 | 源华能源科技（福建）有限公司 | Process for preparing biodiesel by catalytic esterification and alcoholysis of gas-phase methanol |
| CN103113614A (en) * | 2013-02-28 | 2013-05-22 | 天津普莱化工技术有限公司 | PVA (Polyvinyl alcohol) energy-saving and consumption-reducing production new technology method |
| CN106146720A (en) * | 2015-04-17 | 2016-11-23 | 中国石油化工集团公司 | A kind of alcoholysis method in ethylene-vinyl alcohol copolymer preparation process |
| WO2017035734A1 (en) * | 2015-08-31 | 2017-03-09 | Yashentech Corporation | Process for producing dimethyl carbonate |
-
2020
- 2020-09-15 CN CN202010965723.0A patent/CN114181332B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE728742A (en) * | 1968-02-23 | 1969-08-21 | ||
| US3985719A (en) * | 1974-10-21 | 1976-10-12 | National Distillers And Chemical Corporation | Process for the controlled alcoholysis of ethylene-vinyl ester interpolymers |
| CA2399167A1 (en) * | 2001-09-03 | 2003-03-03 | Kuraray Co., Ltd. | Ethylene-vinyl alcohol copolymer composition, and powdery coating composition comprising it |
| CN101709100A (en) * | 2009-12-18 | 2010-05-19 | 浙江大学 | Method for preparing polyethylene-vinyl alcohol copolymer by catalysis-free hydrolysis of polyethylene vinyl acetate in near-critical water |
| CN102703223A (en) * | 2012-05-31 | 2012-10-03 | 源华能源科技（福建）有限公司 | Process for preparing biodiesel by catalytic esterification and alcoholysis of gas-phase methanol |
| CN103113614A (en) * | 2013-02-28 | 2013-05-22 | 天津普莱化工技术有限公司 | PVA (Polyvinyl alcohol) energy-saving and consumption-reducing production new technology method |
| CN106146720A (en) * | 2015-04-17 | 2016-11-23 | 中国石油化工集团公司 | A kind of alcoholysis method in ethylene-vinyl alcohol copolymer preparation process |
| WO2017035734A1 (en) * | 2015-08-31 | 2017-03-09 | Yashentech Corporation | Process for producing dimethyl carbonate |
Non-Patent Citations (1)
| Title |
|---|
| 乙烯-乙烯醇共聚物的合成研究进展;侯悖;于鲁强;;石油化工(第12期);全文 * |
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