CN101407578A - Technology for improving polyester esterification reaction speed - Google Patents
Technology for improving polyester esterification reaction speed Download PDFInfo
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- CN101407578A CN101407578A CNA2008101701963A CN200810170196A CN101407578A CN 101407578 A CN101407578 A CN 101407578A CN A2008101701963 A CNA2008101701963 A CN A2008101701963A CN 200810170196 A CN200810170196 A CN 200810170196A CN 101407578 A CN101407578 A CN 101407578A
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Abstract
The invention discloses a technique for improving esterification reaction speed of polyester, which uses nitrogen as auxiliary raw materials; in the process of esterification reaction, nitrogen in gas phase or in liquid phase is sent into a reactor, which breaks the original balance of gas-phase and liquid-phase reaction system, so as to improve the desorption speed of byproduct water, and lead the esterification reaction balance to move toward the positive reaction, and therefore the esterification reaction speed can be improved. With the adoption of the invention, the production capacity of esterification device can be improved about 30 percent without changing the major structure of the polyester device. Owing to the recycling use of nitrogen, the producing cost of unit product is hardly improved, and equipment investment for improving technology is little and therefore, economic benefit is very obvious.
Description
Technical field
The invention belongs to chemical industry, chemical fibre field, is the part of polyester polymer products manufacturing technology.
Background technology
Polyester is a proven technique, has the developing history of four more than ten years.A lot of around the research that improves polyester device throughput for many years, but by improving the research of esterification speed to polyester esterification reactor feeding nitrogen or using and but do not appear in the newspapers.Main polyester product is polyethylene terephthalate (PET) now, PET is the kind of production capacity maximum in the synthon polymkeric substance, except that being applied to make the polyster fibre, also be widely used in making bottle, film, plastics etc., China's Mainland production of polyester ability reached 2,306 ten thousand tons/year in 2007, and output reaches 1,650 ten thousand tons.
Polyethylene terephthalate is a raw material with pure terephthalic acid (PTA) and ethylene glycol (EG), and PTA and EG generate diglycol terephthalate (BHET) through over-churning, and BHET obtains polyester polymers PET through polycondensation.
The production of polyester technology once lived through gap method, semi-continuous process technological process.Live through ester-interchange method and direct esterification method according to the raw material difference.The continuous direct esterification method production technique of main now employing, main technical process are respectively to be three still flow processs of representative and the five still flow processs of representing with Ji Mawei with the Du Pont.The saying that so-called two still flow processs or single still flow process are also arranged recently.
Polyester direct esterification method technological principle:
The main production of polyester (PET) is divided into two portions, and the one, esterification, the 2nd, polycondensation.
Esterification is to be raw material with pure terephthalic acid (PTA) and ethylene glycol (EG), and after chemical reaction generates the technological process of ethylene glycol terephthalate (BHET).Esterification is reversible balanced reaction, and reaction equation is:
For molecular balance is moved to the positive reaction direction, need constantly remove the water in the resultant of reaction.Increase the mole ratio of raw material EG and PTA, also help improving esterification speed.
Esterification is thermo-negative reaction, improves temperature of reaction and helps improving speed of response.But improve the side reaction that temperature will aggravate to generate glycol ether (DEG).Therefore, accelerating to remove water byproduct is a selection of process optimization and technological innovation to improve esterification speed.
The present invention feeds the esterification technique principle of nitrogen
According to reaction equation (1), in the esterification reaction process, it is PTA, EG, BHET (and oligopolymer) and H2O that system's liquid phase is mainly formed; It is EG and H2O that gas phase is mainly formed.According to Raoult's law, system pressure
P＝P
H2O+P
EG (2)
In the reaction process, by the effect of variable valve, system pressure remains unchanged, and the system pressure of setting up departments is constant C,
Then: P=P
H2O+ P
EG=C (3)
After system gas fed nitrogen mutually, it is constant that the liquid phase of system is formed, and gas phase has increased nitrogen in forming, and major ingredient is three kinds of EG, H2O and N2.Keep system pressure when constant, according to Raoult's law,
P
Newly=P
H2O+ P
EG+ P
N2=C (4)
After feeding nitrogen, the dividing potential drop P of water in the gas phase
H2OReduce the dividing potential drop P of ethylene glycol
EGAlso reduce.
In the gas-liquid phase equilibrium system of sealing, interior a certain component of unit time is evaporated to the amount of gas phase and equates that with the amount that drops to liquid phase from gas phase with fixed attention the gaseous phase partial pressure of this component reaches its saturation vapour pressure from liquid phase.When the gaseous phase partial pressure of this component was lower than saturation vapour pressure, the amount that is evaporated to gas phase from liquid phase was just greater than the amount that drops to liquid phase from gas phase with fixed attention, and this steam output increases with differing from of this component gaseous phase partial pressure and saturation vapour pressure with the difference of the amount of falling with fixed attention.The saturation vapour pressure of a certain component is relevant with the temperature of reaction system, and with system in the relation of environmental stress little.In other words, the gaseous phase partial pressure of a certain component and the difference of its saturation vapour pressure are big more, and this component is just fast more to the speed of gas evaporation from liquid phase.
The problem of discussing in order to simplify, suppose that gas phase EG enters partial condensation tower (process tower, dehydration tower) in the esterifier after, all get back to esterifier; Gas phase H2O all removes after entering partial condensation tower; Mass transfer process between the gas-liquid two-phase only occurs in the biphase interface.Then when dynamic response system balance, subsection in the time period very, the water that liquid phase is evaporated to gas phase deduct water that gas phase drops to liquid phase with fixed attention and equal the water that removes from partial condensation tower.
After the esterifier gas phase fed nitrogen, the gaseous phase partial pressure of ethylene glycol and water all reduced, and on the interface of gas-liquid two-phase, liquid phase is constant to the amount of gas evaporation, and the amount that gas phase is fallen with fixed attention to liquid phase reduces.Because material is an equilibrated, the amount of the water of this part minimizing is exactly the amount that increases by the water that partial condensation tower removes.
Be after esterifier feeds nitrogen, although water and glycol content reduction in the gas phase, owing to carrying secretly of nitrogen, the flow that water and ethylene glycol enter partial condensation tower increases, and increases so unit time internal reaction device removes the amount of water.
It is raw material that conventional esterification technique adopts pure terephthalic acid (PTA) and ethylene glycol (EG), adopts antimony-based catalysts such as Antimony Triacetate or antimony glycol, and the germanium of employing series catalysts is also arranged, and carries out esterification under 200 ℃ to 280 ℃ temperature condition.
The characteristics of Du Pont's technology esterification technique are to adopt very high ethylene glycol and pure terephthalic acid's molar ratio and high temperature.The molar ratio that improves ethylene glycol is equivalent to increase reactant concn, helps improving speed of response.Simultaneously, high temperature and high ethylene glycol volumetric molar concentration will increase the dividing potential drop of ethylene glycol in the reactor gas phase, force to bring gas phase water into partial condensation tower, increase the speed that liquid phase water shifts to gas phase, improve esterification speed.Shortcoming is to vaporize ethylene glycol in a large number at the partial condensation tower cooling for reflux, enters reactor after heating up through reboiler (interchanger), a large amount of energy of process consumption of this evaporation, condensation.
The advantage that the present invention has Du Pont's technology concurrently has overcome the shortcoming of Du Pont's technology simultaneously, because the specific heat capacity of nitrogen is much smaller for the vaporization heat of ethylene glycol, adopts nitrogen as expelling water medium save energy more.
In addition, common polyester product also comprises polybutylene terephthalate (PBT), Poly(Trimethylene Terephthalate) (PTT) etc.
Summary of the invention
The present invention adopts nitrogen as auxiliary material, in the polyester esterification reaction process, feed nitrogen to reactor gas phase or liquid phase, break original gas phase and liquid-phase reaction system balance, improve the speed that removes of water byproduct, make the esterification balance move, thereby improve esterification speed to the positive reaction direction.
Adopt the present invention, can under the situation that does not change the production equipment agent structure, improve esterification plant capacity 30%.Because the nitrogen reuse, the nitrogen of actual consumption seldom, the manufacturing cost of unit product does not almost increase, the facility investment that technological transformation increased seldom, economic benefit is very obvious.
The present invention feeds the esterification technique of nitrogen:
Because the polyester technology and equipment varies, and also has nothing in common with each other so implement environment of the present invention.
One, gas phase feeds nitrogen:
1, nitrogen feeds the position of reactor: far away apart from partial condensation tower gas phase ingress; Nearer apart from the esterification liquid phase level, but liquid level do not contacted.
2, nitrogen flow: 1.5-3.5 cubic meter standard nitrogen/hour/every cubic metre of esterifier volume, wherein with 2.0 cubic metres of standard nitrogen/hour/every cubic metre of esterifier volumetric flow rate is for well.
3, nitrogen temperature: 100-260 ℃, wherein with 230 ℃ for well.
4, nitrogen gas purity: greater than 99.99%.
Two, liquid phase feeds nitrogen:
1, nitrogen feeds the position of reactor: the bottom of liquid phase material.
2, nitrogen flow: 1.5-3.5 cubic meter standard nitrogen/hour/every cubic metre of esterifier volume, wherein with 2.0 cubic metres of standard nitrogen/hour/every cubic metre of esterifier volumetric flow rate is for well.
3, nitrogen temperature: 230-280 ℃, wherein to be all mutually with the liquid phase material temperature.
4, nitrogen gas purity: greater than 99.99%.
5, adopt the nitrogen sparger: sparger be shaped as annular, perhaps two annulars, perhaps cruciform perhaps adds cruciform in the middle of the annular.
6, liquid phase feeds the mixing functions that nitrogen can the partial reinforment material.
Three, nitrogen circulating system:
After partial condensation tower outlet, before non-condensable gas discharging atmosphere a surge tank is set, surge tank is kept malleation, nitrogen compressor is set nitrogen is sent to esterifier from surge tank.Replenish a small amount of fresh nitrogen to surge tank,, keep the malleation of surge tank by controlling the aperture of fresh nitrogen valve.
Four, esterification of the present invention is meant generation ester group-COO-that takes place between carboxyl-COOH and the hydroxyl-OH and the reaction of deviating from water, include but are not limited to esterification, the pure terephthalic acid and 1 of the esterification of pure terephthalic acid and ethylene glycol, smart m-phthalic acid and ethylene glycol, the esterification of 4-butyleneglycol, pure terephthalic acid and 1, the esterification of ammediol.
Following raw materials according that this esterification adopts:
(1), the industrial chemicals with carboxyl includes but are not limited to: terephthalic acid, m-phthalic acid, phthalic acid, hexanodioic acid, sebacic acid, suberic acid, Succinic Acid, propanedioic acid, 1,4 cyclohexanedicarboxylic acid;
(2), the industrial chemicals with hydroxyl includes but are not limited to: ethylene glycol, 1, ammediol, 1,4-butyleneglycol, 1,4 cyclohexane dimethanol, hot pentanediol, glycol ether, polyoxyethylene glycol.
Five, the technology of the present invention is equally applicable to:
1, the esterification that takes place between the industrial chemicals of the industrial chemicals of single carboxyl and single hydroxyl, for example esterification that takes place between acetic acid and propyl carbinol, acetic acid and isopropylcarbinol, acetic acid and n-propyl alcohol, acetic acid and the Virahol;
2, the esterification that takes place between the industrial chemicals of single carboxyl and the bishydroxy worker raw material, for example esterification that takes place between acetic acid and the ethylene glycol;
3, the esterification that takes place between the industrial chemicals of single hydroxyl and the two carboxyl industrial chemicals, for example esterification that takes place between propyl carbinol and the hexanodioic acid.
Six, save cost in order to reduce nitrogen consumption, design cycle of the present invention is used nitrogen, after the partial condensation tower gaseous phase outlet, non-condensable gas is provided with a malleation surge tank before discharging big gas outlet, a nitrogen compressor is set the nitrogen in the surge tank is sent to esterifier, simultaneously carry fresh nitrogen to surge tank, aperture by control nitrogen valve, keep the surge tank internal pressure and be in malleation, surge tank nitrogen was brought up to 110-280 ℃ through heat exchange with temperature before entering esterifier.
Seven, the homogeneity that nitrogen distributes in order to improve liquid phase and to feed nitrogen adopts after the nitrogen sparger, and esterifier still can be provided with agitator; Scheme also can not be provided with agitator as an alternative.
Eight, according to principle of the present invention, can use the polyester process of the method improvement Du Pont technology that feeds nitrogen, reduce the volumetric molar concentration ratio of Du Pont's technology ethylene glycol and PTA, cut down the consumption of energy.
Other operation of esterification technique is identical with conventional esterification technique with process control condition.
Embodiment
One, gas phase feeds nitrogen:
1, nitrogen feeds the position of reactor: far away apart from partial condensation tower gas phase ingress; Nearer apart from the esterification liquid phase level, but liquid level do not contacted.
2, nitrogen flow: 1.5-3.5 cubic meter standard nitrogen/hour/every cubic metre of esterifier volume, wherein with 2.0 cubic metres of standard nitrogen/hour/every cubic metre of esterifier volumetric flow rate is for well.
3, nitrogen temperature: 100-260 ℃, wherein with 230 ℃ for well.
4, nitrogen gas purity: greater than 99.99%.
Two, liquid phase feeds nitrogen:
1, nitrogen feeds the position of reactor: the bottom of liquid phase material.
2, nitrogen flow: 1.5-3.5 cubic meter standard nitrogen/hour/every cubic metre of esterifier volume, wherein with 2.0 cubic metres of standard nitrogen/hour/every cubic metre of esterifier volumetric flow rate is for well.
3, nitrogen temperature: 230-280 ℃, wherein to be all mutually with the liquid phase material temperature.
4, nitrogen gas purity: greater than 99.99%.
5, adopt the nitrogen sparger: sparger be shaped as annular, perhaps two annulars, perhaps cruciform perhaps adds cruciform in the middle of the annular.
6, liquid phase feeds the mixing functions that nitrogen can the partial reinforment material.
Three, nitrogen circulating system:
After partial condensation tower outlet, before non-condensable gas discharging atmosphere a surge tank is set, surge tank is kept malleation, nitrogen compressor is set nitrogen is sent to esterifier from surge tank.Replenish a small amount of fresh nitrogen to surge tank,, keep the malleation of surge tank by controlling the aperture of fresh nitrogen valve.
Other operation of esterification technique is identical with conventional esterification technique with process control condition.
Embodiment 1:
Structure of reactor as shown in Figure 1, wherein: 1 is vacuum valve, 2 is the partial condensation tower inlet valve, 3 is the partial condensation tower outlet valve, 4 is T-valve, 5 is charging opening, 6 and 7 is nitrogen interface and valve, 8 is sampling valve, 9 is discharge port.
According to PTA 5.0kg, EG 3.2kg, Antimony Triacetate 2.5g proportioning raw materials materials allocating is dropped into reactor in the back well, closed reactor with nitrogen replacement gas phase air, heats up.Simultaneously, feed nitrogen and keep reactor internal pressure (gauge pressure) about 2.5kg/cm2, when the reactor content temperature reached 230 ℃, this moment, system pressure was (gauge pressure) about 2.5kg/cm2, and esterification possesses reaction conditions.Begin slowly to open partial condensation tower (process tower) outlet valve, measure the water yield, calculate degree and calculating esterification speed that esterification is finished.When temperature of charge reaches 230 ℃ of reactors and begins water outlet, still feed nitrogen and keep system pressure in 2.5kg/cm2 (gauge pressure), control nitrogen air intake valve and partial condensation tower flowing water Valve aperture are not carried ethylene glycol secretly or are carried ethylene glycol less secretly to guarantee the water of deviating from.When gas phase is led to nitrogen, about 80 minutes of esterification deadline.When liquid phase is led to nitrogen, about 90 minutes of esterification deadline.The same terms does not feed the simultaneous test of nitrogen, and the esterification deadline is about 100-110 minute.
When gas phase fed nitrogen, nitrogen entered reactor by nitrogen interface and valve (Fig. 1 6).When liquid phase fed nitrogen, nitrogen was connected to sampling valve (Fig. 1 8) by pipeline, enters reactor by sampling valve.
Use specific gravity hydrometer and graduated cylinder to detect the amount that the ethylene glycol of carrying secretly in the amount of water and the water is deviate from the reaction of collecting in the beaker.When aquifer yield reach the theoretical aquifer yield of complete esterification 80% the time, be considered as esterification in the experiment and finish, can begin to carry out polycondensation, remaining esterification is finished when polycondensation.
Embodiment 2:
Claims (7)
1, technology that improves polyester esterification speed of the present invention, its technical characterictic is:
Adopt nitrogen as auxiliary material, in the polyester esterification reaction process, feed nitrogen to reactor gas phase or liquid phase, break original gas phase and liquid equilibrium system, make the esterification balance move to the positive reaction direction, thereby improve esterification speed, production equipment adopts the present invention, can be under the situation of modifier agent structure not, improve esterification plant capacity 30%, nitrogen circulation is used, the nitrogen of loss seldom, the facility investment that technological transformation increased is also seldom;
This esterification is meant generation ester group-COO-that takes place between carboxyl-COOH and the hydroxyl-OH and the reaction of deviating from water.
2, a technology that improves polyester esterification speed according to claim 1 is characterized in that adopting following raw materials according:
(1), the industrial chemicals with carboxyl includes but are not limited to: terephthalic acid, m-phthalic acid, phthalic acid, hexanodioic acid, sebacic acid, suberic acid, Succinic Acid, propanedioic acid, 1,4 cyclohexanedicarboxylic acid;
(2), the industrial chemicals with hydroxyl includes but are not limited to: ethylene glycol, 1, ammediol, 1,4-butyleneglycol, 1,4 cyclohexane dimethanol, hot pentanediol, glycol ether, polyoxyethylene glycol.
3, according to claim 1,2 described technology that improve polyester esterification speed, it is characterized in that present technique is equally applicable to:
(1), the esterification that takes place between the industrial chemicals of the industrial chemicals of single carboxyl and single hydroxyl, for example esterification that takes place between acetic acid and propyl carbinol, acetic acid and isopropylcarbinol, acetic acid and n-propyl alcohol, acetic acid and the Virahol;
(2), the esterification that takes place between the industrial chemicals of single carboxyl and the bishydroxy worker raw material, for example esterification that takes place between acetic acid and the ethylene glycol;
(3), the esterification that takes place between the industrial chemicals of single hydroxyl and the two carboxyl industrial chemicals, for example esterification that takes place between propyl carbinol and the hexanodioic acid.
4, a technology that improves polyester esterification speed according to claim 1, it is characterized in that after the partial condensation tower gaseous phase outlet, non-condensable gas is provided with a malleation surge tank before discharging big gas outlet, a nitrogen compressor is set the nitrogen in the surge tank is sent to esterifier, simultaneously carry fresh nitrogen to surge tank, aperture by control nitrogen valve, keep the surge tank internal pressure and be in malleation, surge tank nitrogen was brought up to 110-280 ℃ through heat exchange with temperature before entering esterifier.
5, a technology that improves polyester esterification speed according to claim 1, it is characterized in that liquid phase feeds nitrogen, adopt the nitrogen sparger, distributing homogeneity when improving nitrogen feeding reactor, the nitrogen sparger adopts the annular gas sparger, perhaps double-doughnut gas distributor, perhaps the crisscross gas sparger perhaps adds criss-cross gas distributor in the middle of the annular;
Adopt after the nitrogen sparger, esterifier still can be provided with agitator; Scheme also can not be provided with agitator as an alternative.
6, a technology that improves polyester esterification speed according to claim 1 is characterized in that the polyester process with the method improvement Du Pont technology that feeds nitrogen, reduces the volumetric molar concentration ratio of Du Pont's technology ethylene glycol and PTA, cuts down the consumption of energy.
7, nitrogen feeds the position: during gas phase feeding nitrogen, nitrogen inlet is far away as far as possible apart from the distance of partial condensation tower inlet, still can not touch liquid level apart from liquid level is near.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102311540A (en) * | 2011-09-08 | 2012-01-11 | 中国石油天然气集团公司 | Continuous production system of poly(trimethylene terephthalate) |
| CN102649840A (en) * | 2012-05-14 | 2012-08-29 | 高鼎精细化工(昆山)有限公司 | Novel alcohol-removing equipment for production of polyester polyol |
| CN104028178A (en) * | 2013-03-06 | 2014-09-10 | 中石化上海工程有限公司 | Method for reinforcing mixing effect of hydraulic reactor |
-
2008
- 2008-10-14 CN CNA2008101701963A patent/CN101407578A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102311540A (en) * | 2011-09-08 | 2012-01-11 | 中国石油天然气集团公司 | Continuous production system of poly(trimethylene terephthalate) |
| CN102649840A (en) * | 2012-05-14 | 2012-08-29 | 高鼎精细化工(昆山)有限公司 | Novel alcohol-removing equipment for production of polyester polyol |
| CN104028178A (en) * | 2013-03-06 | 2014-09-10 | 中石化上海工程有限公司 | Method for reinforcing mixing effect of hydraulic reactor |
| CN104028178B (en) * | 2013-03-06 | 2016-03-02 | 中石化上海工程有限公司 | The method of fortified water mechanics reactor mixed effect |
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Application publication date: 20090415 |