CN212595699U

CN212595699U - Final polycondensation reactor

Info

Publication number: CN212595699U
Application number: CN202021066179.8U
Authority: CN
Inventors: 何胜君; 汪少朋; 李金平; 高驰; 朱兴松; 钱继兵
Original assignee: Beijing Xinyou Engineering Technology Co ltd; Nanjing Haoyang Chemical Equipment Co ltd; China Petroleum and Chemical Corp; Sinopec Yizheng Chemical Fibre Co Ltd
Current assignee: Beijing Xinyou Engineering Technology Co ltd; Nanjing Haoyang Chemical Equipment Co ltd; China Petroleum and Chemical Corp; Sinopec Yizheng Chemical Fibre Co Ltd
Priority date: 2020-06-11
Filing date: 2020-06-11
Publication date: 2021-02-26
Anticipated expiration: 2030-06-11

Abstract

The utility model discloses a final polycondensation reactor, which comprises a cylinder body and a disc stirrer arranged in the cylinder body, wherein the disc stirrer comprises two flower discs which are oppositely arranged, a rigid support piece is connected between the two flower discs, and circular rings are fixed on the rigid support piece at intervals; one end of the flower disc is connected with the driving device, and the other end of the flower disc is rotatably supported in the cylinder body. The utility model can realize three forms of stirring, thereby obviously improving the film forming devolatilization efficiency, and the required discs are few, the equipment is light in weight and small in volume; can not establish the axis of rotation, utilize rigidity support piece to replace traditional axis of rotation, can effectively reduce high-viscosity polyester melt and hang the dish and glue the axle, increase the material and take off the area of volatilizing, alleviateed disc agitator's volume and weight simultaneously.

Description

Final polycondensation reactor

Technical Field

The utility model relates to a reactor especially relates to a final polycondensation reactor.

Background

Currently, PET melt polymerization reactors generally employ two forms of agitation. One is stirring with a hollow shaft cage (squirrel cage stirring), and the other is a disk stirrer. In the 80 s, a five-kettle flow technology improved by German Gima company is adopted, a solid shaft disc stirring is adopted in a final polycondensation reactor, the five-kettle flow technology is mainly used for producing fiber-grade PET, and the intrinsic viscosity is generally controlled to be 0.690 dL/g. The working principle of the reactor is that the materials after the pre-polycondensation treatment are adhered to the surface of a disc by the rotation of the disc arranged in the reactor, a drooping film with a certain thickness is formed under the action of gravity and a scraper arranged on the inner wall of a cylinder, a new interface is continuously generated in the reactor disc along with the continuous gliding of a liquid film, an interface updating phenomenon is formed, ethylene glycol molecules removed from PET are allowed to escape at the interface and the drooping film, molecular chains are gradually increased, the polycondensation reaction is continuously carried out under the action of the rotation of the disc and the replacement of the liquid level, and the polyethylene glycol terephthalate is obtained. However, since the liquid films formed by the conventional final polycondensation reactor are all perpendicular to the driving shaft of the disc, that is, the liquid films are only formed in the plane of the disc, the surface area of the polyester melt for evaporating the ethylene glycol in the PET is small, and in order to increase the evaporation area and the gas phase flow area, the commonly adopted method is to increase the volume of the cylinder body and additionally arrange a plurality of groups of discs in the cylinder body, but the final polycondensation reactor adopting the method has the problems that the internal space of the reactor cannot be fully utilized, the volume of the reactor is too large, the occupied space is too large, the cost is too high and the like, and cannot meet the production of the polyester with the intrinsic viscosity of more than 0.750 dL/g.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: the utility model aims at providing a film-forming devolatilization efficiency is high, the required number of discs is small, the equipment weight is light, and the volume is small.

The technical scheme is as follows: the final polycondensation reactor comprises a cylinder body and a disc stirrer arranged in the cylinder body, wherein the disc stirrer comprises two flower discs which are oppositely arranged, a rigid support piece is connected between the two flower discs, and circular rings are fixed on the rigid support piece at intervals; at least one end of the flower disc is connected with a driving device and used for driving the circular ring to rotate.

In order to increase the film-forming devolatilization efficiency, a disk is fixed on the rigid support member at the inner side of the circular ring. The disc is provided with a plurality of through holes for film forming to form a porous disc, the porous disc plays a role in enhancing and supporting the stirrer on one hand, and performs disc surface film forming on the high-viscosity polyester melt on the other hand, and the high-viscosity polyester melt is further subjected to film forming and devolatilization at the through holes of the disc surface to improve the viscosity. When high-viscosity materials pass through the through holes in the circular ring and the circular disc, due to the fact that the viscosity of the materials is high, the materials can flow slowly on the circular ring, the materials can form effective films on the circular ring and the porous disc surface, the film forming area is large, the time is long, the devolatilization area is effectively increased, and the tackifying effect is achieved. The utility model discloses the device can realize the stirring of three kinds of forms, and porous disc film forming, rigidity support piece draw membrane, ring film forming perpendicularly to showing and improving the film forming and having taken off and waving efficiency, consequently, comparing with conventional disc reactor, effectively having reduced the disc quantity and the reactor length of disc section, alleviateed equipment weight and volume.

In order to further improve the effect of stirring and film forming, the area of the disc accounts for 0.05-0.25 of the area of the section of the cylinder; the diameter of the outer circle of the circular ring accounts for 0.05-0.5 of the diameter of the cylinder; the clearance between the top end of the circular ring and the inner wall of the cylinder body is 2-8 mm.

The rigid support piece rotates along with the driving shaft, on one hand, the circular ring is driven to rotate, the high-viscosity polyester melt is disturbed to be uniformly mixed, and on the other hand, the film is vertically pulled to assist devolatilization of the high-viscosity polyester melt. In order to increase the disturbance effect and the film drawing efficiency, a plurality of rigid supporting pieces are arranged, and the rigid supporting pieces are fixed in the circumferential direction of the two faceplates at intervals; further, the rigid supporting piece is arranged along the axial direction of the cylinder body; the cross section of the rigid support part is circular or polygonal, and the polygonal rigid support part is helpful for scraping off the polyester melt attached to the wall of the cylinder by the stirrer in the rotating process; in order to have better stirring supporting effect and film forming effect, the diameter of the rigid supporting piece accounts for 0.25-0.5 of the diameter of the cylinder.

Preferably, still including set up in the cage agitator in the barrel, further, the cage agitator sets up in the barrel front portion, the disc agitator sets up in the barrel rear portion, forms the form of preceding cage rear disc.

Has the advantages that: compared with the prior art, the utility model, can gain following beneficial effect: 1. the stirring in three modes can be realized, so that the film forming devolatilization efficiency can be obviously improved, and the required discs are few, the equipment is light in weight and small in volume; 2. the rigid support piece is used for replacing the traditional rotating shaft without the rotating shaft, so that a hanging disc and a sticking shaft of high-viscosity polyester melt can be effectively reduced, the devolatilization area of materials is increased, and the volume and the weight of the disc stirrer are reduced; 3. can obviously improve the polymerization rate, increase the viscosity of the polyester melt and stably produce the PET polyester with high intrinsic viscosity. 4. The final polycondensation reactor can be used for liquid-phase tackifying the polyester melt for low-viscosity bottles to a high-viscosity state of 0.7-0.95 dL/g.

Drawings

Fig. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic cross-sectional view of a disk agitator of the present invention;

fig. 3 is a schematic cross-sectional view of the faceplate and the rigid support member of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in figures 1-3, the utility model discloses a final polycondensation reactor, which comprises a cylinder body, and can be a cylinder body in other forms for a sealed horizontal structure. The left end of the cylinder body is provided with a material inlet 20, and the right end is provided with a material outlet 24; the feed end is the front end, and the discharge end is the rear end. The front end and the rear end of the cylinder are respectively connected with a driving device, and the driving device respectively comprises a front stirring motor 1, a rear stirring motor 19, a front transmission case 2, a rear transmission case 18, a front differential mechanism 3, a rear differential mechanism 17 and a front transmission shaft 4, a rear transmission shaft 26 which are sequentially connected with the front stirring motor 1 and the rear stirring motor 1; the front end and the rear end of the cylinder are respectively provided with a front end cover 6 and a rear end cover 15, and the rear end is provided with a right shaft seal 16. The front section and the middle section of the barrel are respectively provided with a front-end bubbling liquid level meter 5 and a middle-section bubbling liquid level meter 8 for detecting liquid level, and the rear-section high-viscosity discharge port adopts a radioactive source liquid level meter 14 for detecting liquid level. The middle section and the rear section of the cylinder body are respectively provided with a middle section vacuum pumping hole 9 and a rear section vacuum pumping hole 13.

The inside of the barrel is provided with a disc stirrer, the disc stirrer comprises two flower discs 23 which are arranged in parallel relatively left and right, the front end flower disc 23 is rotationally fixed in the barrel through a right supporting frame 22, and the rear end flower disc 23 is connected with a rear transmission shaft 26. The rigid support piece 11 is connected between the two faceplates 23, the rigid support piece 11 is provided with a plurality of rigid support pieces 11, the plurality of rigid support pieces 11 are fixed in the circumferential direction of the left faceplate 23 and the right faceplate 23 at intervals, the rigid support pieces 11 are arranged along the axial direction of the cylinder body, and the number of the rigid support pieces can be set according to specific requirements. The cross-sectional shape of the rigid support member 11 is not limited and may be circular or polygonal, and the rigid support member 11 helps the stirrer to scrape off the polyester melt attached to the wall of the cylinder during rotation; in order to have a better stirring supporting effect and a better film forming effect, the diameter of the rigid supporting part 11 accounts for 0.25-0.5 of the diameter of the cylinder. The rigid support 11 rotates along with the driving shaft, on one hand, the ring 10 is driven to rotate, the high-viscosity polyester melt is disturbed and uniformly mixed, and on the other hand, the vertical film drawing assists the devolatilization of the high-viscosity polyester melt.

A plurality of groups of rings 10 arranged at intervals are fixed on the rigid support member 11 and are used for driving the rings 10 to rotate and drawing the film. In order to increase the efficiency of film-forming devolatilization, a disk 12 is fixed on the rigid support 11 inside the ring 10. Wherein, a through hole is arranged on the disc 12. The porous disc 12 plays a role in enhancing and supporting the stirrer on one hand, and performs disc surface film forming on the high-viscosity polyester melt on the other hand, and the high-viscosity polyester melt is further subjected to film forming and devolatilization at the through hole of the disc 12 surface to improve the viscosity. When high-viscosity materials pass through the through holes in the circular ring 10 and the disc 12, due to the fact that the viscosity of the materials is high, the materials have low flowing speed on the circular ring 10, the materials can form effective films on the surfaces of the circular ring 10 and the porous disc 12, the film forming area is large, the time is long, the devolatilization area is effectively increased, and the tackifying effect is achieved. The utility model discloses the device can realize the stirring of three kinds of forms, and porous disc film forming, rigidity support piece 11 draw membrane, ring film forming perpendicularly to showing and improving the film forming and having taken off and waving efficiency, consequently, comparing with conventional disc reactor, effectively having reduced the disk quantity and the reactor length of disc section, alleviateed equipment weight and volume. In order to further improve the effect of stirring and film forming, the area of the disc 12 accounts for 0.05-0.25 of the cross section area of the cylinder; the diameter of the circular ring 10 accounts for 0.05-0.5 of the diameter of the cylinder; the clearance between the top end of the circular ring 10 and the inner wall of the cylinder body is 2-8 mm.

The fixed scraper with the inclination angle is additionally arranged between the circular ring 10 and the circular ring 10, so that the film forming effect is improved, and the inclination angle is 15-75 degrees. A plurality of groups of annular scrapers are arranged below the rigid support piece 11, so that the high-viscosity polyester melt can be conveniently scraped from the wall of the reactor, and the adhesion of the high-viscosity polyester melt on the inner wall of the cylinder at the discharge end is reduced.

Still including setting up in the cage agitator 7 of barrel front end in the barrel, the front end of cage agitator 7 is connected with the drive arrangement of barrel front end, and the rear end is rotatable to be fixed in the barrel through left branch strut 21. The cage frame stirrer and the disc stirrer can rotate at different rotating speeds by the front end and the rear end of the cylinder.

The method for producing polyester by using the final polycondensation reactor comprises the following steps:

the PET bottle grade polyester is prepared from terephthalic acid, isophthalic acid, ethylene glycol and phosphoric acid as raw materials, wherein the isophthalic acid accounts for 0.25 percent of the total weight of the synthetic polyester, the terephthalic acid accounts for 70.65 percent of the total weight of the synthetic polyester, the ethylene glycol accounts for 29 percent of the total weight of the synthetic polyester, and the phosphoric acid accounts for 10-50ppm of the total weight of the polyester. After terephthalic acid, isophthalic acid, ethylene glycol and phosphoric acid are subjected to pulping, esterification and precondensation, the inherent viscosity of the precondensed polyester melt is controlled to be 0.15 dL/g.

The pre-polycondensation polyester melt enters a final polycondensation reactor and reacts for 100min under the conditions that the reaction temperature is 265 ℃ and the absolute pressure is 10 Pa. The length ratio of the stirring cage frame section to the disc section of the reactor is 1:0.2, the low-viscosity pre-polycondensation polyester melt is efficiently filmed under the action of the cage frame, the contents of ethylene glycol in the polyester melt and ethylene glycol generated by polycondensation are higher at the moment, the viscosity of the polyester melt is rapidly increased under the vacuum action, and the stirring rotating speed is generally set at 6rpm at the moment.

After the polyester melt is devolatilized through the film forming of the cage frame section, the intrinsic viscosity is increased to be about 0.6dL/g, the film forming effect of the polyester melt at the tail part of the cage frame section is weakened along with the increase of the dynamic viscosity of the polyester melt, the thickness of a liquid film is increased, micromolecules such as glycol generated by polycondensation and the like cannot be effectively volatilized, the driving force of the polycondensation reaction is reduced, and the viscosity increase of the polyester melt is slowed down. At the moment, the polyester melt begins to enter the disc stirrer for film forming and devolatilization, and three forms of vertical film forming of a circular ring, a porous disc and a rigid supporting strip are included. The disc section adopts a plurality of groups of hollow circular rings, the minimum clearance between the circular rings and the reactor wall is controlled to be 2mm, the diameter of the rigid supporting piece supported by the disc section accounts for 0.25 of the diameter of the reactor, a porous disc is arranged in the disc section, the number ratio of the porous disc to the hollow circular rings is 1:1, the area of the porous disc accounts for 0.05 of the cross section area of the reactor, and the excircle diameter of the hollow circular ring accounts for 0.05 of the diameter of the reactor. Because disc segment polyester melt viscosity is higher, too high rotational speed can lead to the liquid film not to come the shaping, is unfavorable for the micromolecule desorption, and high rotational speed produces adverse effect to the radius and the shape of ring in addition, is easy to scrape especially on the basis of with reactor wall precision fit, and stirring rotational speed generally sets up at 2rpm this moment. The polyester melt from the final polycondensation reactor is tackified to 0.7dL/g from a low-viscosity bottle polyester melt liquid phase, the carboxyl end group of the polyester melt is 40mol/t, the melting point is 255 ℃, the L value is 84, and the b value is-3.

Claims

1. A final polycondensation reactor comprises a cylinder body and a disc stirrer arranged in the cylinder body, and is characterized in that the disc stirrer comprises two flower discs (23) which are oppositely arranged, a rigid support member (11) is connected between the two flower discs (23), and circular rings (10) are fixed on the rigid support member (11) at intervals; at least one end of the flower disc (23) is connected with a driving device and used for driving the circular ring to rotate.

2. The final polycondensation reactor according to claim 1, wherein a disk (12) is fixed to the rigid support (11) inside the ring (10).

3. The final polycondensation reactor according to claim 1, wherein the disk (12) is provided with through holes for film formation.

4. The final polycondensation reactor according to claim 1, wherein the rigid support members are fixed at intervals in the circumferential direction of the two faceplates (23).

5. The final polycondensation reactor according to claim 2, wherein the area of the disk (12) is 0.05 to 0.25 of the cross-sectional area of the cylinder.

6. The final polycondensation reactor according to claim 1, wherein the outer diameter of the ring (10) is 0.05 to 0.5 of the diameter of the cylinder.

7. The final polycondensation reactor according to claim 1, wherein the rigid support (11) has a diameter of 0.25 to 0.5 of the diameter of the cylinder.

8. The final polycondensation reactor according to claim 1, wherein the rigid support (11) has a circular or polygonal cross-sectional shape.

9. The final polycondensation reactor according to claim 1, wherein the clearance between the top end of the ring (10) and the inner wall of the cylinder is 2 to 8 mm.

10. The final polycondensation reactor of claim 1 further comprising a cage agitator disposed within the barrel.