CN112110794A - Production method of polyester-grade ethylene glycol - Google Patents
Production method of polyester-grade ethylene glycol Download PDFInfo
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- CN112110794A CN112110794A CN202010923718.3A CN202010923718A CN112110794A CN 112110794 A CN112110794 A CN 112110794A CN 202010923718 A CN202010923718 A CN 202010923718A CN 112110794 A CN112110794 A CN 112110794A
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- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 title claims abstract description 420
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 238000005984 hydrogenation reaction Methods 0.000 claims abstract description 94
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229920000728 polyester Polymers 0.000 claims abstract description 34
- 238000000926 separation method Methods 0.000 claims abstract description 32
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000007788 liquid Substances 0.000 claims abstract description 31
- 239000002994 raw material Substances 0.000 claims abstract description 29
- 239000007791 liquid phase Substances 0.000 claims abstract description 23
- 238000011084 recovery Methods 0.000 claims abstract description 22
- 238000002834 transmittance Methods 0.000 claims abstract description 9
- 238000010992 reflux Methods 0.000 claims abstract description 8
- 230000018044 dehydration Effects 0.000 claims abstract description 7
- 238000006297 dehydration reaction Methods 0.000 claims abstract description 7
- 239000000126 substance Substances 0.000 claims abstract description 7
- 239000001257 hydrogen Substances 0.000 claims description 26
- 229910052739 hydrogen Inorganic materials 0.000 claims description 26
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 19
- 239000011344 liquid material Substances 0.000 claims description 16
- 239000003054 catalyst Substances 0.000 claims description 15
- 239000007789 gas Substances 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 7
- 238000009835 boiling Methods 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical group [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 6
- 239000012071 phase Substances 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 6
- 150000002431 hydrogen Chemical class 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 5
- 238000001179 sorption measurement Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 150000001298 alcohols Chemical class 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229920006395 saturated elastomer Polymers 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 230000003139 buffering effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 6
- 239000003245 coal Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- 230000008901 benefit Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 230000002528 anti-freeze Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000013064 chemical raw material Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- 239000001760 fusel oil Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229940083957 1,2-butanediol Drugs 0.000 description 1
- RSWGJHLUYNHPMX-UHFFFAOYSA-N Abietic-Saeure Natural products C12CCC(C(C)C)=CC2=CCC2C1(C)CCCC2(C)C(O)=O RSWGJHLUYNHPMX-UHFFFAOYSA-N 0.000 description 1
- JVTAAEKCZFNVCJ-UHFFFAOYSA-M Lactate Chemical compound CC(O)C([O-])=O JVTAAEKCZFNVCJ-UHFFFAOYSA-M 0.000 description 1
- LOMVENUNSWAXEN-UHFFFAOYSA-N Methyl oxalate Chemical compound COC(=O)C(=O)OC LOMVENUNSWAXEN-UHFFFAOYSA-N 0.000 description 1
- KHPCPRHQVVSZAH-HUOMCSJISA-N Rosin Natural products O(C/C=C/c1ccccc1)[C@H]1[C@H](O)[C@@H](O)[C@@H](O)[C@@H](CO)O1 KHPCPRHQVVSZAH-HUOMCSJISA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- BMRWNKZVCUKKSR-UHFFFAOYSA-N butane-1,2-diol Chemical compound CCC(O)CO BMRWNKZVCUKKSR-UHFFFAOYSA-N 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 208000026438 poor feeding Diseases 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- KHPCPRHQVVSZAH-UHFFFAOYSA-N trans-cinnamyl beta-D-glucopyranoside Natural products OC1C(O)C(O)C(CO)OC1OCC=CC1=CC=CC=C1 KHPCPRHQVVSZAH-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/88—Separation; Purification; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification of at least one compound
- C07C29/90—Separation; Purification; Use of additives, e.g. for stabilisation by treatment giving rise to a chemical modification of at least one compound using hydrogen only
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
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Abstract
The invention provides a production method of polyester-grade ethylene glycol, and relates to the technical field of refined ethylene glycol. The production method is realized by a rectification system and a liquid phase hydrogenation reactor, wherein the rectification system comprises: a methanol recovery tower, a dehydration tower, a dealcoholization tower, an ethylene glycol product tower and an ethylene glycol recovery tower; the liquid phase hydrogenation reactor comprises: the system comprises a buffer tank, a feed pump, a preheater, a hydrogenation reactor, a gas-liquid separation tank, a torch system and a product pump; the production method sequentially comprises the following steps: s1, rectifying in five towers; s2, recovering and buffering; s3, preheating the raw materials; s4, hydrogenation reaction; s5, separating gas and liquid; s6, refluxing and hydrogenating; and S7, producing a finished product. According to the invention, the liquid phase hydrogenation reactor is additionally arranged on the traditional rectification system, the hydrogenation reaction is carried out on the industrial-grade glycol produced by the rectification system, and trace substances influencing the purity and the ultraviolet transmittance of the glycol are converted, so that the quality of the glycol is improved from the industrial grade to the polyester grade, and the polyester-grade yield of the glycol is improved to 100%.
Description
Technical Field
The invention relates to the technical field of refined ethylene glycol, and particularly relates to a production method of polyester-grade ethylene glycol.
Background
Ethylene Glycol (EG) is an important chemical raw material, has wide application and can be used as an antifreezing agent and a raw material of polyester. Ethylene glycol can be mixed with water at will, has high boiling point and low freezing point, is a very common antifreezing agent, is used as an important organic chemical raw material, and is widely applied to the preparation fields of polyester chips, various antifreezing solutions, coolants, rosin esters, drying agents, softeners and the like.
Ethylene glycol is mainly used for producing polyester and automobile antifreeze, and the ethylene glycol consumed by the polyester and the automobile antifreeze accounts for more than 90 percent of the total amount. When the ethylene glycol is used for producing polyester, the requirement on the purity of raw materials is extremely high, and the ethylene glycol is originally called 'high-grade product' ethylene glycol in national standards and is called polyester-grade ethylene glycol at present. In the quality standard of polyester-grade ethylene glycol, there is an ultraviolet transmittance index (UV value) which is measured for ultraviolet light having a wavelength of 350nm, a wavelength of 275nm and a wavelength of 220nm, respectively. The low-content impurities which are not suitable for routine detection in the glycol product have different absorption degrees on the three kinds of wavelength light, so that the ultraviolet light transmittance can accurately reflect the impurity content of the glycol product, and the control value of the index is clearly specified in the national standard. That is, the UV value of ethylene glycol represents to some extent the purity of ethylene glycol.
As shown in figure 1, the coal-based glycol is a new technical route for producing glycol, a vacuum rectification process is adopted, a five-tower rectification process flow is adopted in a rectification working section, a polyester-grade glycol product is finally obtained, and a part of industrial-grade glycol products are by-produced. The methanol recovery tower recovers the methanol in the crude alcohol product; removing water and part of low-boiling point alcohols (fusel oil) in the product at the tower top of the dehydrating tower; the top of the dealcoholization column removes all components with a lower boiling point than ethylene glycol (light fraction), such as: methyl glycolate, 1, 2-butanediol, etc.; the ethylene glycol product tower obtains industrial grade and polyester grade ethylene glycol products; the ethylene glycol recovery tower is used for further recovering ethylene glycol from heavy components in the ethylene glycol product tower, and the recovered ethylene glycol is sent to the ethylene glycol product tower again. The industrial-grade glycol produced by the method has the advantages of low UV value, poor purity, no market, low price and difficult sale. Therefore, the improvement of the polyester grade yield of the ethylene glycol and the improvement of the inherent quality of the product are necessary conditions for stable and economic production of enterprises.
However, the coal-based ethylene glycol is used as a new technical route for producing ethylene glycol, the technological reaction process is different from an ethylene method, and the generated trace impurities are different from those generated in an ethylene route. In the current industrial production process, the polyester grade yield of the ethylene glycol is only about 90 percent. The polyester grade yield of ethylene glycol can also decrease as the process fluctuates or the plant is operated late, which presents significant difficulties and challenges for stable, economical production of the plant.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a production method of polyester-grade ethylene glycol, which solves the problem of low polyester-grade yield of ethylene glycol prepared from coal.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme:
a process for the production of polyester grade ethylene glycol by a rectification system and a liquid phase hydrogenation reactor, the rectification system comprising: a methanol recovery tower, a dehydration tower, a dealcoholization tower, an ethylene glycol product tower and an ethylene glycol recovery tower; the liquid phase hydrogenation reactor comprises: the system comprises a buffer tank, a feed pump, a preheater, a hydrogenation reactor, a gas-liquid separation tank, a torch system and a product pump;
the production method sequentially comprises the following steps:
s1 five-tower rectification
Introducing crude alcohol as a raw material into a rectification system of ethylene glycol; recovering methanol in the crude alcohol by a methanol recovery tower, removing water and part of low-boiling-point alcohols by a dehydration tower, removing all components with the boiling point lower than that of the glycol by a dealcoholization tower, and obtaining industrial-grade glycol and polyester-grade glycol by an ethylene glycol product tower; recovering industrial-grade ethylene glycol from the top of the ethylene glycol recovery tower;
s2 recovery buffer
Recovering industrial-grade ethylene glycol extracted from the top of the ethylene glycol product tower and the top of the ethylene glycol recovery tower, mixing the industrial-grade ethylene glycol and the industrial-grade ethylene glycol, and introducing the mixture serving as a raw material into a buffer tank;
s3, preheating raw materials
The raw materials in the buffer tank are conveyed to a preheater through a feeding pump for heating;
s4 hydrogenation reaction
Mixing the heated raw material with hydrogen, then feeding the mixture into a hydrogenation reactor from the top, and carrying out hydrogenation reaction with the hydrogen under the action of a catalyst to convert trace substances influencing the purity and ultraviolet transmittance (UV value) of the ethylene glycol;
s5, gas-liquid separation
The hydrogenated material is sent into a gas-liquid separation tank from a hydrogenation reactor, the material is subjected to gas-liquid separation in the gas-liquid separation tank, gas is sent into a torch system, and liquid material is pumped out through a product pump;
s6, refluxing and hydrogenating
Sampling and analyzing the liquid material separated from the gas-liquid separation tank every other hour, if the UV value is not increased by more than 25, refluxing to the buffer tank, and repeating the steps from S2 to S5 to hydrogenate again;
s7, producing a finished product
And sampling and analyzing the liquid material separated by the gas-liquid separation tank every other hour, returning to a rectification system if the UV value is increased by more than 25, and finally continuously producing the polyester-grade ethylene glycol after separation by an ethylene glycol product tower.
Preferably, the reaction condition in the hydrogenation reactor is 0.5MPaG, the temperature is 80-110 ℃, and the volume space velocity of the catalyst is 2.5h < -1 >; the hydrogenation reactor is a trickle bed reactor; the ethylene glycol solution and hydrogen flow downwards in parallel, the hydrogen is a continuous phase, and the ethylene glycol solution is a dispersed phase.
Preferably, the pressure after the feeding pump is controlled to be about 0.7MPaG, and the hydrogen is mixed with the raw material after the pressure is reduced to 0.55MPaG and then enters the hydrogenation reactor from the top.
Preferably, the heat source of the preheater is 0.5MPaG saturated steam, and the raw materials are heated to 80-90 ℃.
Preferably, in S4, before the hydrogenation reactor is started, nitrogen is filled into the hydrogenation reactor to replace the medium in the hydrogenation reactor, then hydrogen is filled into the hydrogenation reactor from the top, a vent valve on a vent pipe at the lower section of the hydrogenation reactor is opened, the flow rate of the vented gas is adjusted by a flowmeter, the inert gas and the hydrogen are discharged to a torch system, and the hydrogenation reaction stage is also continuously vented.
Preferably, in the hydrogenation reaction stage, the vent gas is sent to a gas-liquid separation tank, separated by the gas-liquid separation tank and then discharged to a torch system.
Preferably, the hydrogenation catalyst in the hydrogenation reactor is a nickel-based adsorption catalyst.
Preferably, the liquid material produced by the liquid phase hydrogenation reactor returns to the dealcoholization tower of the rectification system.
Preferably, in the early stage of starting the rectification system and after the tower washing, under the condition that the feed components of the liquid phase hydrogenation reactor are very high in quality, the liquid material produced by the liquid phase hydrogenation reactor directly returns to the ethylene glycol product tower of the rectification system.
(III) advantageous effects
The invention provides a production method of polyester-grade ethylene glycol. Compared with the prior art, the method has the following beneficial effects:
according to the invention, the liquid phase hydrogenation reactor is additionally arranged on the traditional rectification system, the hydrogenation reaction is carried out on the industrial-grade glycol produced by the rectification system, and trace substances influencing the purity and the ultraviolet transmittance of the glycol are converted, so that the quality of the glycol is improved from the industrial grade to the polyester grade, and the polyester-grade yield of the glycol is improved to 100%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a process for preparing ethylene glycol from coal in the background art of the present invention;
FIG. 2 is a process flow diagram of polyester grade ethylene glycol in an embodiment of the present invention;
fig. 3 is a process flow diagram of a liquid phase hydrogenation reactor in an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described, and it is obvious that the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the application solves the problem of low polyester grade yield of the ethylene glycol prepared from coal by providing the production method of the polyester grade ethylene glycol.
In order to solve the technical problems, the general idea of the embodiment of the application is as follows:
according to the embodiment of the invention, the liquid phase hydrogenation reactor is additionally arranged on the traditional rectification system, the hydrogenation reaction is carried out on the industrial-grade glycol produced by the rectification system, and trace substances influencing the purity and the ultraviolet transmittance of the glycol are converted, so that the quality of the glycol is improved from the industrial grade to the polyester grade, and the polyester grade yield of the glycol is improved to 100%.
In order to better understand the technical solution, the technical solution will be described in detail with reference to the drawings and the specific embodiments.
Example 1:
as shown in fig. 2 and fig. 3, the present invention provides a method for producing polyester grade ethylene glycol, wherein the method is implemented by a rectification system and a liquid phase hydrogenation reactor, and the rectification system comprises: a methanol recovery tower, a dehydration tower, a dealcoholization tower, an ethylene glycol product tower and an ethylene glycol recovery tower; the liquid phase hydrogenation reactor comprises: the system comprises a buffer tank, a feed pump, a preheater, a hydrogenation reactor, a gas-liquid separation tank, a torch system and a product pump;
the production method sequentially comprises the following steps:
s1 five-tower rectification
Introducing crude alcohol as a raw material into a rectification system of ethylene glycol; recovering methanol in crude alcohol by a methanol recovery tower, removing water and part of low boiling point alcohols (fusel oil) by a dehydration tower, removing all components (light fractions) with the boiling point lower than that of ethylene glycol by a dealcoholization tower, and obtaining industrial grade ethylene glycol and polyester grade ethylene glycol by an ethylene glycol product tower; recovering industrial-grade ethylene glycol from the top of the ethylene glycol recovery tower;
s2 recovery buffer
Recovering industrial-grade ethylene glycol extracted from the top of the ethylene glycol product tower and the top of the ethylene glycol recovery tower, mixing the industrial-grade ethylene glycol and the industrial-grade ethylene glycol, and introducing the mixed raw materials into a buffer tank to ensure that the two raw materials are stably mixed in the buffer tank before entering a hydrogenation reactor;
s3, preheating raw materials
The raw materials in the buffer tank are conveyed to a preheater through a feeding pump for heating, so that the temperature of two strands of raw materials with different temperatures is stable before the two strands of raw materials enter a hydrogenation reactor, the hydrogenation reaction temperature is ensured, and poor reaction effect caused by over-temperature or low temperature is avoided;
s4 hydrogenation reaction
Mixing the heated raw material with hydrogen, then feeding the mixture into a hydrogenation reactor from the top, and carrying out hydrogenation reaction with the hydrogen under the action of a catalyst to convert trace substances influencing the purity and ultraviolet transmittance (UV value) of the ethylene glycol;
s5, gas-liquid separation
The hydrogenated material is sent into a gas-liquid separation tank from a hydrogenation reactor, the material is subjected to gas-liquid separation in the gas-liquid separation tank, gas is sent into a torch system, and liquid material is pumped out through a product pump; the safety accidents caused by the fact that hydrogen dissolved in the liquid material enters a rectification system are prevented;
s6, refluxing and hydrogenating
Sampling and analyzing the liquid material separated by the gas-liquid separation tank every other one hour, if the UV value is not increased by more than 25, refluxing to the buffer tank, repeating S2-S5 for hydrogenation again, and ensuring the quality of the ethylene glycol produced by the hydrogenation reaction;
s7, producing a finished product
And (3) sampling and analyzing the liquid material separated by the gas-liquid separation tank every other hour, returning to a rectification system if the UV value is increased by more than 25, and finally continuously producing the polyester-grade ethylene glycol after separation by an ethylene glycol product tower, wherein the polyester-grade yield of the ethylene glycol is increased to 100%.
As shown in fig. 1 and fig. 2, the top of the ethylene glycol product tower produces industrial grade ethylene glycol, and the middle produces polyester grade ethylene glycol, which is the prior art and will not be described herein.
The reaction condition in the hydrogenation reactor is 0.5MPaG, the temperature is 80-110 ℃, and the volume space velocity of the catalyst is 2.5h < -1 >; the hydrogenation reactor is a trickle bed reactor; the ethylene glycol solution and hydrogen flow downwards in parallel, the hydrogen is a continuous phase, and the ethylene glycol solution is a dispersed phase.
As shown in fig. 3, the pressure after the feeding pump is controlled to be about 0.7MPaG, and hydrogen is decompressed to 0.55MPaG, mixed with the raw material and then enters the hydrogenation reactor from the top, so as to ensure that the reaction pressure in the hydrogenation reactor is controlled to be 0.5 MPaG.
The heat source of the preheater is 0.5MPaG saturated steam, and the raw materials are heated to 80-90 ℃.
As shown in fig. 3, in S4, before the hydrogenation reactor is started, nitrogen is filled to replace the medium in the hydrogenation reactor, hydrogen is then filled from the top of the hydrogenation reactor, an emptying valve on an emptying pipe at the lower section of the hydrogenation reactor is opened, the flow rate of the emptying gas is adjusted by a flowmeter, the inert gas and hydrogen are discharged to a torch system, and the hydrogen concentration and the reaction pressure in the hydrogenation reactor are ensured by continuously emptying the reactor at the hydrogenation reaction stage.
The reaction pressure in the hydrogenation reactor is controlled by the flow of the fed hydrogen and the flow of the vented gas.
In the hydrogenation stage, as shown in fig. 3, in order to prevent the ethylene glycol liquid from being entrained in the vent gas in the S4, the vent gas may be optionally sent to a gas-liquid separation tank, separated by the gas-liquid separation tank, and then discharged to a flare system.
And gas in the buffer tank is discharged to a torch system through a pipeline, so that safety accidents are prevented.
The hydrogenation catalyst in the hydrogenation reactor is a nickel-based adsorption catalyst, has the characteristics of universality for impurity adsorption and high adsorption capacity in a hydrogen environment, and can be used for removing organic impurities such as aldehydes, ketones, carboxylic acids, esters and the like, wherein the removal rate reaches 90-95%.
The normal service life of the hydrogenation catalyst is more than 3 years, the benefit measurement takes one service cycle of the hydrogenation catalyst as a period, and taking a 30 ten thousand ton/year coal-to-ethylene glycol project as an example, the efficiency measurement of the conversion of non-polyester grade ethylene glycol into polyester grade ethylene glycol is carried out. The measurement basis is as follows: according to the operation condition of the similar device, the dimethyl oxalate main hydrogenation catalyst is used for a whole period, and the quality polyester grade yield of the ethylene glycol product is averagely 92%. The price difference between the polyester grade glycol and the non-polyester grade glycol is 300 yuan/ton (the price difference fluctuates greatly, and the minimum value is taken here). The synergy is as follows: 30 ten thousand tons/year (1-92%) 300 yuan/ton 3 yuan. The production method of the polyester-grade ethylene glycol has obvious effect on enterprises and extremely high practicability.
As shown in fig. 2, the liquid material produced by the liquid phase hydrogenation reactor is returned to the dealcoholization tower of the rectification system.
Example 2:
as shown in fig. 2, in the early stage of the start-up of the rectification system and after the tower washing, under the condition that the feed components of the liquid phase hydrogenation reactor are very good, the liquid material produced by the liquid phase hydrogenation reactor directly returns to the ethylene glycol product tower of the rectification system.
In summary, compared with the prior art, the invention has the following beneficial effects:
1. according to the embodiment of the invention, the liquid phase hydrogenation reactor is additionally arranged on the traditional rectification system, the hydrogenation reaction is carried out on the industrial-grade glycol produced by the rectification system, and trace substances influencing the purity and the ultraviolet transmittance of the glycol are converted, so that the quality of the glycol is improved from the industrial grade to the polyester grade, and the polyester grade yield of the glycol is improved to 100%.
2. In the embodiment of the invention, the buffer tank is arranged, so that two streams of ethylene glycol raw materials entering the hydrogenation reactor can be stabilized, and the hydrogenation effect is ensured.
3. In the embodiment of the invention, the preheater is arranged, so that the temperature of two strands of raw materials with different temperatures is stable before entering the hydrogenation reactor, the hydrogenation reaction temperature is ensured, and poor reaction effect caused by over-temperature or low temperature is avoided.
4. In the embodiment of the invention, the gas-liquid separation tank is arranged to flash-evaporate the hydrogen dissolved in the ethylene glycol so as to prevent the part of the dissolved hydrogen from entering the rectification system and causing safety risk to the rectification system.
5. In the embodiment of the invention, the quality of the ethylene glycol produced by the hydrogenation reaction is ensured through the reflux design, particularly, the reaction time is prolonged under the condition of very poor feeding quality, the reaction effect is ensured, and the ethylene glycol produced by the liquid phase hydrogenation reactor reaches the standard.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. A production method of polyester-grade ethylene glycol is characterized in that the production method is realized by a rectification system and a liquid phase hydrogenation reactor, wherein the rectification system comprises: a methanol recovery tower, a dehydration tower, a dealcoholization tower, an ethylene glycol product tower and an ethylene glycol recovery tower; the liquid phase hydrogenation reactor comprises: the system comprises a buffer tank, a feed pump, a preheater, a hydrogenation reactor, a gas-liquid separation tank, a torch system and a product pump;
the production method sequentially comprises the following steps:
s1 five-tower rectification
Introducing crude alcohol as a raw material into a rectification system of ethylene glycol; recovering methanol in the crude alcohol by a methanol recovery tower, removing water and part of low-boiling-point alcohols by a dehydration tower, removing all components with the boiling point lower than that of the glycol by a dealcoholization tower, and obtaining industrial-grade glycol and polyester-grade glycol by an ethylene glycol product tower; recovering industrial-grade ethylene glycol from the top of the ethylene glycol recovery tower;
s2 recovery buffer
Recovering industrial-grade ethylene glycol extracted from the top of the ethylene glycol product tower and the top of the ethylene glycol recovery tower, mixing the industrial-grade ethylene glycol and the industrial-grade ethylene glycol, and introducing the mixture serving as a raw material into a buffer tank;
s3, preheating raw materials
The raw materials in the buffer tank are conveyed to a preheater through a feeding pump for heating;
s4 hydrogenation reaction
Mixing the heated raw material with hydrogen, then feeding the mixture into a hydrogenation reactor from the top, and carrying out hydrogenation reaction with the hydrogen under the action of a catalyst to convert trace substances influencing the purity and ultraviolet transmittance (UV value) of the ethylene glycol;
s5, gas-liquid separation
The hydrogenated material is sent into a gas-liquid separation tank from a hydrogenation reactor, the material is subjected to gas-liquid separation in the gas-liquid separation tank, gas is sent into a torch system, and liquid material is pumped out through a product pump;
s6, refluxing and hydrogenating
Sampling and analyzing the liquid material separated from the gas-liquid separation tank every other hour, if the UV value is not increased by more than 25, refluxing to the buffer tank, and repeating the steps from S2 to S5 to hydrogenate again;
s7, producing a finished product
And sampling and analyzing the liquid material separated by the gas-liquid separation tank every other hour, returning to a rectification system if the UV value is increased by more than 25, and finally continuously producing the polyester-grade ethylene glycol after separation by an ethylene glycol product tower.
2. The method for producing polyester grade ethylene glycol according to claim 1, wherein the reaction conditions in the hydrogenation reactor are 0.5MPaG, 80 to 110 ℃, and the catalyst volume space velocity is 2.5h "1; the hydrogenation reactor is a trickle bed reactor; the ethylene glycol solution and hydrogen flow downwards in parallel, the hydrogen is a continuous phase, and the ethylene glycol solution is a dispersed phase.
3. The process for producing polyester grade ethylene glycol according to claim 2, wherein the pressure after the feed pump is controlled to about 0.7MPaG, and the hydrogen gas is mixed with the raw material after being depressurized to 0.55MPaG and then enters the hydrogenation reactor from the top.
4. The method for producing polyester grade ethylene glycol according to claim 2, wherein the preheater has a heat source of 0.5MPaG saturated steam and heats the raw material to 80-90 ℃.
5. The process for producing polyester grade ethylene glycol according to claim 1, wherein in S4, before the hydrogenation reactor is started, nitrogen is filled to replace the medium in the hydrogenation reactor, then hydrogen is filled from the top of the hydrogenation reactor, a vent valve on a vent pipe at the lower section of the hydrogenation reactor is opened, the flow of vent gas is adjusted through a flowmeter, inert gas and hydrogen are discharged to a torch system, and the hydrogenation reaction stage is continuously vented.
6. The process for producing polyester-grade ethylene glycol according to claim 5, wherein in the S4, in the hydrogenation reaction stage, the vent gas is sent to a gas-liquid separation tank, separated by the gas-liquid separation tank and discharged to a flare system.
7. The method for producing polyester grade ethylene glycol according to any one of claims 1 to 6, wherein the hydrogenation catalyst in the hydrogenation reactor is a nickel-based adsorption catalyst.
8. The method for producing polyester grade ethylene glycol according to any one of claims 1 to 6, wherein the liquid material produced by the liquid phase hydrogenation reactor is returned to the dealcoholization tower of the rectification system.
9. The method for producing polyester grade ethylene glycol according to any one of claims 1 to 6, wherein the liquid material produced by the liquid phase hydrogenation reactor directly returns to the ethylene glycol product tower of the rectification system when the feed components of the liquid phase hydrogenation reactor are very good at the early stage of the start-up of the rectification system and after the tower washing.
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