CN113769666A - Reactor and method for producing low-small-molecular-content polyester - Google Patents
Reactor and method for producing low-small-molecular-content polyester Download PDFInfo
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- CN113769666A CN113769666A CN202010521930.7A CN202010521930A CN113769666A CN 113769666 A CN113769666 A CN 113769666A CN 202010521930 A CN202010521930 A CN 202010521930A CN 113769666 A CN113769666 A CN 113769666A
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- 229920000728 polyester Polymers 0.000 title claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 43
- 239000002245 particle Substances 0.000 claims abstract description 32
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 9
- 238000001816 cooling Methods 0.000 claims description 18
- 238000004321 preservation Methods 0.000 claims description 18
- 238000009826 distribution Methods 0.000 claims description 15
- 150000003384 small molecules Chemical class 0.000 claims description 11
- 239000008187 granular material Substances 0.000 claims description 9
- 239000000498 cooling water Substances 0.000 claims description 8
- 239000007789 gas Substances 0.000 claims description 6
- 239000003638 chemical reducing agent Substances 0.000 claims description 3
- 238000009413 insulation Methods 0.000 claims 2
- 239000008188 pellet Substances 0.000 claims 2
- 230000017525 heat dissipation Effects 0.000 claims 1
- 238000013461 design Methods 0.000 abstract description 7
- 238000002156 mixing Methods 0.000 abstract description 4
- 238000012546 transfer Methods 0.000 abstract description 4
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 22
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 9
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 6
- 239000000428 dust Substances 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 239000007790 solid phase Substances 0.000 description 5
- HGINCPLSRVDWNT-UHFFFAOYSA-N Acrolein Chemical compound C=CC=O HGINCPLSRVDWNT-UHFFFAOYSA-N 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 229920000139 polyethylene terephthalate Polymers 0.000 description 4
- 239000005020 polyethylene terephthalate Substances 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000012798 spherical particle Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- -1 Polyethylene terephthalate Polymers 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000007791 dehumidification Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/12—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by gravity in a downward flow
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/0015—Feeding of the particles in the reactor; Evacuation of the particles out of the reactor
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/78—Preparation processes
- C08G63/785—Preparation processes characterised by the apparatus used
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
The invention discloses a reactor and a method for producing low-micromolecule-content polyester, which can realize plug flow in the particle conveying process through the design of a circular coil splitter plate, are not easy to cause back mixing, provide stable airflow by a hot nitrogen/air outlet pipe, and fully transfer heat and mass with spherical polyester particles, thereby greatly improving the micromolecule removal efficiency of the polyester particles.
Description
Technical Field
The invention relates to a reactor and a method for producing low-small-molecular-content polyester.
Background
Polyethylene terephthalate (PET) is a semi-crystalline thermoplastic polyester that is widely used in the manufacture of fibers, films, sheets, and food trays and beverage containers. In the prior art, terephthalic acid (PTA) and Ethylene Glycol (EG) are used as main raw materials to prepare high-viscosity polyester, low-viscosity polyester with the intrinsic viscosity of about 0.65dl/g and the polymerization degree of about 100 is obtained through conventional liquid phase polymerization, and then high-viscosity polyester with the intrinsic viscosity of 0.80dl/g and the average polymerization degree of more than 135 is improved through a solid-phase tackifying process, so that the high-viscosity polyester meets the requirements of subsequent processing.
In polyester packaging products, besides intrinsic viscosity, the content of small molecules is another most important index, particularly acetaldehyde (AA), can permeate into packaged objects to produce adverse effects, and if food is packaged, the taste of food is directly influenced and health risks are caused to human bodies. The sources of acetaldehyde are mainly: in the liquid phase polymerization stage, part of AA with the content of about 100 mu g/g is formed due to high-temperature degradation reaction; partial side reactions occur in the solid phase tackifying stage, and a small amount of AA is produced. AA generated by the two sources can be basically removed in the solid-phase tackifying process, and the final AA content is not more than 1.0 mu g/g. Although the solid-phase tackifying technology is mature, hot nitrogen/air is usually adopted to remove small molecules in polyester solid particles and improve viscosity, the technology has the problems of high energy consumption and material consumption, uneven molecular weight distribution of PET products, much dust and the like. In the existing production technology, the liquid phase tackifying technology is to make PET reach higher intrinsic viscosity (generally above 0.78 dL/g) in a final polycondensation reactor, perform underwater crystallization, cutting and granulation, and then realize the preparation of a final polyester product through a micromolecule removing device. The preparation of polyester chips with low small molecular weight content aiming at the crystallized spherical particles obtained by liquid phase tackifying is of great importance in the structural design and process conditions of the reactor in the production flow.
At present, all existing reactors are designed by tower body structures of conventional cylindrical polyester particles, so that polyester chips fall unevenly by means of dead weight, the stacking density of the polyester particles is low, plug flow cannot be effectively formed, heat exchange is uneven, back mixing is easily caused, the existing tubular heat exchanger at a cooling section has a short cleaning period due to impurity precipitation, the removal efficiency of small molecules in the chips is low, and the replacement period of dust removal bags of a cooler is greatly influenced by the outside.
Disclosure of Invention
The purpose of the invention is as follows: the present invention aims to provide a reactor and a method for producing low-molecular-weight polyester, so as to solve the technical problems.
The technical scheme is as follows: the reactor for producing the low-small-molecular-weight polyester comprises a vertical two-section reactor, wherein the upper section of the reactor is a cylinder, and the lower section of the reactor is an inverted cone; the top of the reactor is provided with a feed inlet and an air outlet, and the reactor is provided with a first air inlet and a second air inlet; the cylinder body is divided into a heat preservation area and a cooling area, and a flow distribution plate and an air outlet pipe positioned on the central axis of the heat preservation area are arranged in the heat preservation area; the air outlet pipe is provided with a plurality of air outlets, and an inlet of the air outlet pipe is connected with the first air inlet; the flow distribution plate is formed by nesting a plurality of circular rings on the same plane or is honeycomb-shaped.
The method for producing the polyester with low small molecular content is based on the reactor of any one of claims 1 to 9, and is characterized by comprising the following steps,
(1) spherical polyester particles enter a heat preservation area of the reactor from a feed inlet at the top of the reactor, and hot air or nitrogen is introduced from a first air inlet of the reactor to remove small molecules in the particles;
(2) the polyester granules with most of small molecules removed enter a cooling zone, and are cooled by cooling water and cold air or nitrogen, and the small molecules in the granules are further removed;
(3) the particles are discharged from the outlet and enter the next process.
The heat preservation area of the reactor in the step (1) passes through a jacket heat preservation device, the internal temperature is maintained at 160-200 ℃, the retention time is 15-40h, and the temperature of hot air or nitrogen is 160-200 ℃.
The temperature of the cooling water in the step (2) is less than or equal to 40 ℃, the circulating flow rate in the pipe is 1.0-2.0m/s, and the residence time of the particles in the cooling section is not more than 3 hours.
The ratio of the amount of the particles in the steps (1) and (2) to the amount of the introduced air or nitrogen is 5-25.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:
(1) the heat preservation area is provided with a hollow cylindrical hot nitrogen/air outlet pipe, and the air outlet pipe is connected with a hot nitrogen/air inlet pipe outside the tower through the bottom of the heat preservation area, so that stable airflow in the whole tower is provided to fully perform heat and mass transfer by forward and reverse collision with spherical polyester particles, and each particle can obtain the same contact opportunity.
(2) The circular coil splitter plate is embedded at the top and the middle of the nitrogen outlet pipe, so that the distribution uniformity of materials in the reactor is fully improved, the circular coil splitter plate is matched with the air inlet pipe, the contact area of the materials and gas is further increased, the circular coil splitter plate is particularly suitable for removing small molecules from granular materials, the problem of back mixing can be solved, the plug flow in the process of conveying sliced particles is realized, and the efficiency of removing the small molecules from polyester slices can be greatly improved.
(3) The cooling area of the invention adopts the design of a spiral coil type heat exchanger, one or more layers of fins are arranged outside the spiral coil and welded on the outer surface of the spiral coil to increase the heat exchange area, and the surface area of the heat exchange tube is as follows: the tube pass surface area is 1: 4-1: 6, the length-diameter ratio is more than or equal to 2, the condensed water performs heat exchange through rotational flow movement of the spiral channel outside the tube, the heat transfer coefficient is high, the space utilization rate is high, fluid in the spiral tube further strengthens convective heat exchange under the action of centrifugal force, impurities in the condensed water are easy to take away, and frequent cleaning of the heat exchanger is avoided. The condensed water is recycled, energy loss of a cooler in the conventional production flow is avoided, and the energy-saving and environment-friendly effects are achieved.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of the structure of the splitter plate of the present invention;
FIG. 3 is another schematic view of the diverter plate of the present invention;
FIG. 4 is a schematic view of a partial structure of a spiral coil heat exchanger according to the present invention;
fig. 5 is a horizontal cross-sectional view of the spiral coil heat exchanger of the present invention.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
The tower body of the reactor 2 of the present invention as shown in fig. 1 is of a two-stage vertical design and comprises a cylindrical section 1 and an inverted cone section 3. The center of the top of the tower body is provided with a feed inlet 22 and a gas phase outlet 21, and the tail end of the inverted cone at the lower end is provided with a reactor material outlet 23. The cylinder section is divided into a warm-keeping zone 10 and a cooling zone 11. The cooling zone 11 has a smaller diameter than the holding zone 10 in order to ensure that the material has different residence times in the two zones.
A hollow cylindrical hot nitrogen/air outlet pipe 103 is arranged on the central axis of the heat preservation area 10, the air outlet pipe 103 is connected with a first air inlet 105 through a pipeline at the bottom of the heat preservation area, the inlet air is nitrogen or air, and the diameter of an air outlet hole on the pipe wall of the air outlet pipe 103 is smaller than that of spherical polyester particles. Be equipped with flow distribution plate 102 in heat preservation district 10, flow distribution plate nestification is outside air-out pipe 103, and the flow distribution plate is equipped with 1 layer at least. The splitter plate 102 is formed by nesting a plurality of rings with different diameters, the rings are all located on the same plane, and the apparent arrangement is uniform, as shown in fig. 2. The diverter plate 102 may also be honeycomb shaped, with each honeycomb having a polygonal configuration, as shown in fig. 3. The outer diameter of the air outlet pipe is the minimum diameter of the inner ring of the circular coil pipe splitter plate, and the joint of the air outlet pipe and the circular coil pipe splitter plate has no dead angle. The upper and lower flow distribution plates 102 are welded and supported by cylindrical supports 104, the discs are connected by the supports, and the circular coil pipes and the supports are made of solid. The ratio of the distance between the adjacent circular rings of the flow distribution plate to the diameter of the reactor is more than 1:11, and the thickness of the flow distribution plate is less than 100mm, preferably 30-100 mm.
The outer wall of the cylinder of the tower body of the heat preservation area 10 is provided with a jacket heat preservation device which can maintain the temperature in the tower.
As shown in fig. 4, a spiral coil heat exchanger 111 is disposed in the cooling zone 11, and the heat exchanger is composed of a plurality of vertically disposed tube passes 116 and a spiral coil 115 surrounding the outside of the tube passes, and a certain gap is formed between the tube passes surrounding the spiral coil. The particles fall from the tube pass of the heat exchanger by gravity or vibration, and cooling water enters from a cooling water inlet 113 arranged below the cooling section, passes through the spiral coil, flows out from a cooling water outlet 112 arranged above the spiral coil, and circulates in the spiral coil outside the tube pass. Surface area of the heat exchange tube: the surface area of the cylinder is 1: 4-1: 6, and the length-diameter ratio is more than or equal to 2. Fins with certain width are horizontally arranged on the outer wall of the spiral coil pipe to increase heat exchange between the spiral coil pipe and the cold air or nitrogen which moves upwards.
A reducing pipe 4 is arranged in the inverted cone 3 at the lower section, and the reducing pipe 4 and the shell of the inverted cone 3 form an annular space which is in a double-top cone design. The outer shell of the inverted cone 3 is provided with a second gas inlet 31, the position of the second gas inlet corresponds to the annular space, dry air or nitrogen enters the tube bundle of the heat exchanger through an annular gap generated by the cone, and particles fall from the reducer 4.
The method for producing the polyester with low small molecular content by adopting the device specifically comprises the following steps:
spherical polyester particles enter a first section of heat preservation area of the tower body from a feed inlet at the top of the reactor, wherein the viscosity of the spherical polyester particles at the feed inlet is 0.70-0.80dL/g, the acetaldehyde content is 10-100 mu g/g, the formaldehyde content is 10-50 mu g/g, and the crystallinity is 30-40%. The particles fall to the circular coil pipe splitter plate by means of dead weight and then are split and descend, because the contact area among the spherical polyester particles is small, relative displacement is easy to occur, so that the speed in the falling process is uneven, the stacking density is smaller than that of the cylindrical particles, the design of the splitter plate can keep the descending speed of the middle and the edge of the spherical polyester particles balanced, the plug flow is effectively formed, stable airflow in the whole tower is provided in the hot nitrogen/air outlet pipe, the heat and mass transfer is fully carried out by forward and reverse collision of the spherical polyester particles, each particle can obtain the same contact opportunity, and therefore the micromolecule removal efficiency is improved. The micromolecules are formaldehyde, acetaldehyde, acrolein, benzene, toluene, ethylbenzene, xylene, styrene and the like. The jacket of the cylinder body is kept at the temperature of 160-200 ℃ for 15-40 h.
A uniform cooling zone for removing most of small molecular polyester particles, wherein the cooling zone adopts a spiral coil type heat exchanger, cooling circulates from a spiral coil from bottom to top, the particles fall down from the tube pass of the heat exchanger by virtue of gravity, the temperature of cooling water is less than or equal to 40 ℃, the circulating flow rate in the tube is 1.0-2.0m/s, the residence time of the cooling zone is 1-3h, and the temperature of the polyester particles after passing through the cooling zone is about 40 ℃.
The cone at the lower section of the reactor adopts a double-top cone design, and simultaneously plays a role of a flow guide cone, so that the descending speed of spherical particles in the middle part and the edge of the reactor is balanced, and the back mixing of a discharge port is avoided. Dry air or nitrogen is continuously blown into the heat exchanger tube bundle through the annular gap generated by the cone, fully contacts with the spherical particles from top to bottom, and continuously discharges formaldehyde, acetaldehyde, acrolein gas and micromolecules in the tower body. The exhausted air/nitrogen can be recycled after dehumidification and catalyst absorption of moisture, formaldehyde, acetaldehyde and micromolecules. The ratio of the amount of the granules to the air/nitrogen in the whole micromolecule removal process is 5-25, wherein the temperature of the hot air/nitrogen is 160-200 ℃, and preferably 170-185 ℃.
The acetaldehyde content of the spherical polyester granules prepared by the reactor is lower than 1 mu g/g, the formaldehyde content is lower than 0.8 mu g/g, the dust content is lower than 10 mu g/g, the crystallinity is lower than 50%, the initial melting temperature is lower than 230 ℃, the dust proportion is reduced by 80% compared with that of polyester slices produced by a conventional solid-phase tackifying and dealdehyding device, the difference of the internal and external viscosities of the granules is lower than 0.01dL/g, the molecular weight distribution is less than or equal to 2.3, and the post-processing injection molding temperature of a user is reduced by 10-15 ℃.
The polyester granules produced by the above reactor, the dust was collected by a cyclone to obtain the dust content, and the molecular weight distribution and the formaldehyde and acetaldehyde contents were also measured with reference to the polyester test standard (GB17931-2003) and the results are shown in the following table:
Claims (13)
1. a reactor for producing low-small-molecule-content polyester is characterized by comprising a two-section reactor (2), wherein the upper section of the reactor is a cylindrical section (1), the lower section of the reactor is an inverted cone section (3), and the tail end of the inverted cone section is provided with a discharge hole (23); the top of the reactor (2) is provided with a feed inlet (22) and an air outlet (21), and the reactor is also provided with a first air inlet (105) and a second air inlet (31); the cylinder section (1) is divided into a heat preservation area (10) and a cooling area (11), and a flow distribution plate (102) and an air outlet pipe (103) located on the central axis of the heat preservation area are arranged in the heat preservation area (10); a plurality of air outlets are arranged on the air outlet pipe (103), and an inlet of the air outlet pipe (103) is connected with the first air inlet (105); the flow distribution plate (103) is formed by nesting a plurality of circular rings on the same plane or is in a honeycomb shape.
2. The reactor for producing low-small-molecule-content polyester according to claim 1, wherein the flow distribution plate (102) is provided with at least two layers.
3. The reactor for producing low-molecular-weight polyester according to claim 1, wherein the outer wall of the reactor in the holding zone (10) is provided with a jacket holding device.
4. Reactor for the production of polyesters with a low small molecular weight content according to claim 1, characterized in that the cooling zone (11) is provided with a spiral coil heat exchanger (111) consisting of several vertically arranged tube passes (116) and a spiral coil (115) surrounding the outside of the tube passes.
5. The reactor for producing low-molecular-weight polyester according to claim 4, wherein the spiral coil (115) is provided with fins (114) for heat dissipation.
6. The reactor for producing low-molecular-weight polyester according to claim 1, wherein the diameter of the air outlet pipe (103) is smaller than the diameter of the particles.
7. The reactor for producing low-small-molecule-content polyester according to claim 1, wherein the ratio of the surface area of the spiral pipe in the heat exchanger to the surface area of the reactor is 1:4 to 1: 6.
8. The reactor for producing low-small-molecule-content polyester according to claim 1, wherein the ratio of the distance between the adjacent circular rings of the splitter plate (103) to the diameter of the reactor is more than 1:11, and the thickness of the splitter plate is less than 100 mm.
9. The reactor for producing a low molecular weight polyester as claimed in claim 1, wherein a reducer (3) is provided in said inverted cone section (3), said reducer (4) forming an annular space with the outer shell of said inverted cone section (3), and said second gas inlet (31) being provided in said inverted cone outer shell.
10. A method for producing a low-molecular-weight polyester, which is based on the reactor of any one of claims 1 to 9, and comprises the following steps,
(1) spherical polyester particles enter a heat preservation area of the reactor from a feed inlet at the top of the reactor, and hot air or nitrogen is introduced from a first air inlet of the reactor to remove small molecules in the particles;
(2) the polyester granules with most of small molecules removed enter a cooling zone, and are cooled by cooling water and cold air or nitrogen, and the small molecules in the granules are further removed;
(3) the particles are discharged from the outlet and enter the next process.
11. The method for producing low-molecular-weight polyester as claimed in claim 10, wherein the reactor insulation zone in step (1) is maintained at an internal temperature of 160-200 ℃ by a jacket insulation device, the residence time is 15-40h, and the temperature of hot air or nitrogen is 160-200 ℃.
12. The method for producing a low-molecular-weight polyester according to claim 10, wherein the temperature of the cooling water in the step (2) is 40 ℃ or lower, the circulating flow rate in the tube is 1.0 to 2.0m/s, and the residence time of the pellets in the cooling zone is not more than 3 hours.
13. The method for producing low-molecular-weight polyester according to claim 10, wherein the ratio of the amount of the pellets in the steps (1) and (2) to the amount of the introduced air or nitrogen is 5 to 25.
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| DE602005007573D1 (en) * | 2005-03-24 | 2008-07-31 | Giuliano Cavaglia | Method of using a reactive atmosphere for the continuous or discontinuous solid state polymerization of polyesters |
| CN101842208A (en) * | 2007-08-24 | 2010-09-22 | 乌德伊万塔-费希尔有限公司 | Prepare the method for low in hydrolysis polyester granulate and the equipment of preparation polyester granulate from the high viscosity polyester melt |
| CN102276815A (en) * | 2011-07-11 | 2011-12-14 | 大连海新工程技术有限公司 | Integrated roof filling polyester solid tackifying reactor |
| CN102295764A (en) * | 2011-07-11 | 2011-12-28 | 大连海新工程技术有限公司 | Process of integrated ridge-filling reactor for polyester solid-phase tackification |
| CN203065381U (en) * | 2013-01-18 | 2013-07-17 | 扬州惠通化工技术有限公司 | PET (polyethylene terephthalate) section aldehyde removal tower |
| CN107228557A (en) * | 2017-07-25 | 2017-10-03 | 魏玉芳 | A kind of paddy hot air circulation removes chaff integrated device using dry |
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