WO2007128159A1

WO2007128159A1 - A disc cage final polycondensation reactor

Info

Publication number: WO2007128159A1
Application number: PCT/CN2006/000289
Authority: WO
Inventors: Wende Luo; Huatang Zhou; Aijun Gu; Chun Zhang; Jiaqi Huang; Haodong Xu
Original assignee: China Textile Industrial Engineering Institute
Priority date: 2006-02-28
Filing date: 2006-02-28
Publication date: 2007-11-15
Also published as: RU2008123941A; RU2403968C2

Abstract

A disc cage final polycondensation reactor comprises an inclosed horizontal barrel having a feed inlet, a product outlet and an air outlet. A stirring device including stirring baskets and driving axles is disposed inside the barrel. The stirring baskets constitute of the baskets for low, medial and high viscous materials respectively. The driving axles constitute of the axles for the reaction zone of low and medial viscous materials and the reaction zone of high viscous materials respectively. Both the basket for low viscous materials and the basket for medial viscous materials are driven by the driving axle for low and medial viscous materials to carry out stirring. The basket for high viscous materials is driven by the driving axle for high viscous materials to carry out stirring.

Description

Cage tray final polycondensation reactor

The present invention relates to a cage disc final polycondensation reactor, and more particularly to a final polycondensation reactor for the final polycondensation reaction of polyethylene terephthalate (PET). Background technique

In the preparation of polyesters, especially in the preparation of polyethylene terephthalate (PET) by esterification and polycondensation using ethylene glycol (EG) and terephthalic acid (PTA). The polymerization process of the polyester generally includes a pre-polycondensation reaction and a final polycondensation reaction, wherein the final polycondensation reaction is mainly controlled by the transmission rate.

Prior to this, polyester final polycondensation reactors generally used high liquid hold horizontal reactors, which provided longer material residence times and a very large evaporation area to accommodate high throughput requirements. In the prior art, the final polycondensation reactor is classified according to flow type, and has a plug flow and a multi-stage series full mixed flow type, etc.; according to the type of the agitator of the reactor, there are a disc type, a cage type, and the like.

Generally, the disc reactor is single-shaft type, the agitator adopts a combination disc in a low-viscosity zone, and the high-viscosity zone adopts a single disc structure, and each single disc has a scraper to control the thickness of the single disc holding liquid. When the disc rotates out of the molten pool, the polyethylene terephthalate melt adheres to the surface on both sides of the ring, and under the action of gravity, the polyethylene terephthalate melt flows downward to form Drooping membrane. As the liquid film continues to decline, the new interface is also continuously produced, which forms a so-called interface renewal phenomenon, and small molecules can escape at the interface, so that the polycondensation reaction continues. However, the polycondensation reaction in the low viscosity region of the final polycondensation reactor is not completely completed, the stirring effect of the simple disk is poor, and the molecular collision probability required for polymerization is small; the medium viscosity polyethylene terephthalate melt is held. The thickness is small, the interface update is not ideal; the high viscosity zone uses a single disk, and the interface formed is perpendicular to the axial direction, and the reactor space cannot be fully utilized. Moreover, as the size of the reactor is increased, the rigidity of the single-disc structure is insufficient, and mechanical failure is apt to occur.

The invention patent is directed to the above problems of the prior art, and has been invented a research and development of polyester and related technologies for many years, and has invented a novel cage disk reactor through painstaking research and development. The cage disc reactor divides the drive shaft into three regions according to the characteristics of the viscosity of the material, and the drive shaft of each region adopts a different structure, which fully satisfies the object. The requirements of polycondensation, evaporation and removal of volatile components promote the smooth progress of the reaction to the polymerization direction, while ensuring the mechanical properties of the reactor and achieving safe operation. Summary of the invention

The object of the present invention is to provide a final polycondensation reaction device which adopts a combination of a cage type and a disc type according to the viscosity characteristics of materials in different regions, and adopts a drive shaft of different structure to make the reactor more suitable for the final polycondensation reactor. The requirements of different polycondensation stages are promoted to facilitate the smooth progress of the reaction.

The cage-type final polycondensation reactor of the present invention comprises a sealed transversely-shaped cylinder having a material inlet, a material outlet and an exhaust port, and having a stirring device including a stirring basket and a drive shaft inside the cylinder.

According to a preferred embodiment of the invention, the agitating basket comprises a mixing basket for low viscosity materials, a mixing basket for medium viscosity materials, and a mixing basket for high viscosity materials.

According to another preferred embodiment of the invention, the mixing basket for the low viscosity material comprises a plurality of sets of perforated ring disks, spokes, pitch blades and bottom rings.

According to another preferred embodiment of the invention, the mixing basket for the medium viscosity material comprises a plurality of sets of mesh disks, a bottom ring, an outer ring, spokes and tie rods.

According to another preferred embodiment of the invention, wherein the mixing basket for the high viscosity material comprises a plurality of sets of combined reels, spokes, axial tensile sheets and sleeves.

According to another preferred embodiment of the invention, the drive shaft inside the barrel includes a drive shaft for the reaction zone of the low viscosity and medium viscosity materials and a drive shaft for the high viscosity material reaction zone.

According to another preferred embodiment of the present invention, the agitating basket for the low viscosity material and the agitating basket for the medium viscosity material are driven by the driving shaft for the low viscosity and medium viscosity materials for agitation.

According to another preferred embodiment of the present invention, the agitating basket for the high viscosity material is driven by a drive shaft for the high viscosity material for agitation.

According to another preferred embodiment of the invention, wherein the drive shaft for the low viscosity and medium viscosity material reaction zone is a surface porous hollow shaft.

According to another preferred embodiment of the invention, wherein the reaction is used for high viscosity materials The drive shaft of the zone is a hollow shaft with no holes on the surface.

According to another preferred embodiment of the invention, wherein the pitching blade has an inclination angle α of 5 to 45 degrees, which is preferably 5 to 20 degrees.

According to another preferred embodiment of the present invention, wherein the transversely-shaped cylinder has an oblong cross section, the drive shaft axis is located at the center of the lower circle of the cylinder.

According to another advantageous embodiment of the invention, the vent is located at the top of the cage disc reactor.

The invention further relates to the use of the cage disc final polycondensation reactor for the final polycondensation of polyethylene terephthalate.

The "cage tray type final polycondensation reactor" described in the present invention means a final polycondensation reactor in which a cage type and a tray type are combined.

The low viscosity region I described in the present invention preferably means a region having an intrinsic viscosity of less than about 0.4.

The medium viscosity region II described in the present invention preferably means a region having an intrinsic viscosity of about 0.4 to 0.6.

The high viscosity region referred to in the present invention preferably means a region having an intrinsic viscosity of about 0.6 to 0.9.

The cage-type final polycondensation reactor of the present invention adopts a combination of a cage type, a mesh type and a combined disc type mixing basket according to the viscosity characteristics of materials in different regions, and adopts a drive shaft of different structure (ie, for low The drive shaft of the reaction zone of the viscosity and medium viscosity materials and the drive shaft for the reaction zone of the high viscosity material) make the reactor more suitable for the different polycondensation stages in the final polycondensation reactor, thereby facilitating the smooth progress of the reaction. In addition, the polyester (especially, polyethylene terephthalate) melt can be used in the mixing basket by the action of the perforated ring disk, the mesh disk or the disk ring and the film pulling plate in the use of the reactor. Two membranes are formed, one is a film perpendicular to the drive shaft (obtained by a perforated ring disk, a mesh disk or a ring ring in a mixing basket) and a film parallel to the drive shaft (pulled in the mixing basket) Obtained under the action of the membrane plate). Thereby, the amount of the liquid film of the carried material is increased, the mass transfer area of the reactor is increased, the stirring efficiency is effectively improved, and the melt interface renewal effect formed is good. Further, since the reactor of the present invention has an increased chance of liquid phase film formation, a large evaporation area is provided, and the amount of volatiles which are removed is increased, which is advantageous for the reaction to proceed in the direction in which the polyester is formed. In addition, the cage-type final polycondensation reactor of the present invention has sufficient gas-phase circulation space at the top and is arranged in a row. The gas port facilitates the discharge of gas and enhances the mass transfer effect of the reaction. DRAWINGS

Figure 1 is a longitudinal cross-sectional view showing a preferred embodiment of the cage-type final polycondensation reactor of the present invention;

Figure 2 is a transverse cross-sectional view of a preferred embodiment of the cage disc final polycondensation reactor of the present invention;

Figure 3 is a transverse cross-sectional view of a preferred embodiment of a stirred basket for low viscosity materials in a cage disc final polycondensation reactor of the present invention;

Figure 4 is a schematic illustration of a preferred embodiment of a pitched blade used in a cage-type final polycondensation reactor of the present invention;

Figure 5 is a transverse cross-sectional view of a preferred embodiment of a stirred basket for medium viscosity materials in a cage disc final polycondensation reactor of the present invention;

Figure 6 is a transverse cross-sectional view of a preferred embodiment of a stirred basket for high viscosity materials in a cage disc final polycondensation reactor of the present invention. detailed description

The present invention will be described in detail below with reference to the accompanying drawings 1-6, but it does not constitute a limitation of the present invention:

As shown in Fig. 1, the cage-type final polycondensation reactor of the present invention comprises a sealed transverse cylindrical body 0 having a circular (not shown) or oblong cross section (see Fig. 2). Body 0 is a flat or elliptical head at both ends. The barrel 0 has a material inlet 1 and a material outlet 2 at both ends and an exhaust port 3 at the top. The inside of the cylinder 0 has a stirring device 4 including a stirring basket and a drive shaft. The drive shaft is driven by a drive unit 5 located outside the barrel 0. When the cross section of the cylinder 0 is circular, the drive shaft is located at the center of the circle (not shown); and when the cross section of the cylinder 0 is oblong, the drive shaft is located at the lower center (see Fig. 2) so as to be at the top A sufficient gas phase circulation space is provided, and the exhaust port 3 is provided to facilitate the discharge of gas, thereby enhancing the mass transfer effect of the reaction and promoting the reaction in a direction favorable for polymerization.

According to the viscosity of the material, the inside of the cage-type final polycondensation reactor of the present invention can be divided into three regions: a low viscosity zone I, a medium viscosity zone, and a high viscosity zone III. Thus, the mixing basket is divided into a stirring basket 100 for low-viscosity materials and a stirring basket for medium viscosity materials. 200 and a mixing basket 300 for high viscosity materials. The drive shaft is divided into a drive shaft 400 for low viscosity and medium viscosity materials and a drive shaft 500 for high viscosity materials. The cage-type final polycondensation reactor of the present invention is an axial biaxial structure in which a stirring basket 100 for low-viscosity materials and a stirring basket 200 for medium-viscosity materials are used for driving shafts for low-viscosity and medium-viscosity materials. The 400 drive is used for agitation, and the agitating basket 300 for high viscosity materials is driven by a drive shaft 500 for high viscosity materials for agitation. The drive shaft 400 for low viscosity and medium viscosity materials is a hollow shaft having a superficial surface, and the drive shaft 500 for high viscosity materials is a hollow shaft having a non-porous surface.

Specifically, the low viscosity zone I is near the reactor feed end and is about one-half the length of the drive shaft for the low viscosity and medium viscosity material reaction zone. In the reaction zone, the polyester, especially the polyethylene terephthalate melt has a relatively low molecular weight, a low viscosity of the material, and good fluidity. To increase the degree of polymerization, this zone uses a mixing basket 100 for low viscosity materials and a drive shaft 400 for low viscosity and medium viscosity materials. The low-viscosity cage-type mixing basket 100 is a cage structure with a perforated disc, which can increase the amount of material carrying a lower viscosity. See Figure 3 for the specific structure. The low viscosity zone cage agitator basket 100 includes a plurality of sets of perforated ring discs 101, spokes 102, pitched blades 103 and bottom rings 104, and is welded to a drive shaft 400 having a surface that is rotated therewith. Wherein, the inclined blade 103 disposed on the perforated ring disk 101 and the spokes 102 can cause the polyester (especially, polyethylene terephthalate) melt to generate only radial flow, which can enhance the stirring. The effect is that the blade is welded to the ring and the spokes. In the low-viscosity cage-type mixing basket 100, the disc-to-disk spacing is determined by the length of the pitched blades, and the inclined angle α of the inclined blades (see Fig. 4) along with the polyester (in particular, polyethylene terephthalate) Ester) The viscosity of the melt increases and changes to obtain the best mixing effect and reasonable power consumption. Among them, the inclination angle α is preferably 5-45 degrees. During the agitation process, the perforated coil ring 101 and the spokes 102 can carry a polyester (especially, polyethylene terephthalate) melt from the bottom liquid phase of the reactor to the upper gas phase space to form a liquid film. The gas generated in the polycondensation reaction, such as ethylene glycol, provides an effective escape evaporation surface, so that the small molecule gas phase product generated in the reaction escapes and escapes in time, and promotes the reaction to accelerate the polymerization.

The medium viscosity zone II is located in the middle of the reactor. As the polycondensation reaction rate is slowed down, the viscosity of the material is gradually increased, so as to provide a large evaporation area in a shorter cylinder length, and promote the reaction to accelerate the polymerization. This area mixing basket 200 is adopted The mesh disk structure, the mesh disk structure can increase the amount of the material carrying the medium viscosity, and the specific structure is shown in FIG. 5. The medium viscosity zone agitating basket 200 includes a plurality of sets of mesh plates 201, a bottom ring 202, outer rings 203, 204, 205, spokes 206 and tie rods 207, and the assembled welding basket 200 is welded to the surface porous drive shaft 400. . During the stirring process, the mesh 201 can carry the polyester (especially, polyethylene terephthalate) melt from the bottom liquid phase of the reactor to the upper gas phase space to form a liquid film, which is a gas generated in the polycondensation reaction. For example, ethylene glycol provides an effective escape evaporation surface, so that the small molecule gas phase product generated in the reaction escapes and escapes in time, and promotes the reaction to accelerate the polymerization.

The high viscosity zone III is adjacent to the reactant outlet where the polycondensation reaction enters the completion stage, and therefore, the agitating basket 300 adopts a combined disc structure. The mixing basket can carry a larger amount of liquid with a larger viscosity, and the melt interface has a better renewing effect, and the stability is good to ensure that the melt removes volatiles. At the same time, the drive shaft 500 used in the high-viscosity zone is an independent drive shaft, and the rotation speed can be adjusted according to the needs of the reaction degree, and the rotation speed of the drive shaft in the low-viscosity zone and the medium-viscosity zone can be obtained to obtain a better devolatilization effect. Specifically, the specific structure of the stirring basket for high viscosity is shown in FIG. 6. It includes a plurality of sets of the ring 301, the spokes 302 and the axial tensile plate 303, the sleeve 304, and is assembled in a drive shaft for high viscosity materials. 500. Wherein, the axial tensile film 30; 3 is tangentially entered into the polyester (especially, polyethylene terephthalate) molten pool and welded to the ring and the spoke. In this way, the axial tensile film enters the polyester (especially, polyethylene terephthalate) melt pool tangentially as the drive shaft rotates, and the polyester (especially, the poly Ethylene terephthalate) The melt carries the pull-up to form a parallel axial polyester (especially polyethylene terephthalate) melt film, polyester flowing down the coil (especially , polyethylene terephthalate) The melt film forms a melt film perpendicular to the axial direction, and two membranes are formed by the stirring basket 300, which increases the mass transfer area of the reactor, and at the same time The stirring action makes the molecular weight distribution of the polyester (particularly, polyethylene terephthalate) more reasonable.

The cage-type final polycondensation reactor of the present invention can use polyester (especially, polyethylene terephthalate) melt by the perforated ring disk 101, the mesh plate 201 in the stirring basket or Two membranes are formed under the action of the disc ring 301 and the tensile diaphragm 303, one is a membrane perpendicular to the drive shaft (obtained by the perforated ring disc 101, the mesh 201 or the disc ring 301 in the agitating basket) and a film parallel to the drive shaft (from the mixing basket) Obtained by the action of the film plate 303). Thereby, the amount of the liquid film of the carried material is increased, the mass transfer area of the reactor is increased, the stirring efficiency is effectively improved, and the melt interface renewal effect formed is good. Further, since the reactor of the present invention has an increased chance of liquid phase film formation, a large evaporation area is provided, and the amount of volatiles removed is increased, which is advantageous for the reaction to form a polyester (particularly, polyethylene terephthalate). The direction is proceeding. Since the mixing basket is designed according to the characteristics of the viscosity of different reaction stages, the cage type (perforated ring disc 101), disc type (mesh disc 201) or combined disc type (ring 301) can be used to increase the materials carrying different viscosities. The amount of liquid film promotes the reaction. At the same time, the molecular weight distribution of the polyester (particularly, polyethylene terephthalate) is more reasonable due to the stirring action of the stirring basket. In addition, the cage-type final polycondensation reactor of the invention has sufficient gas-phase circulation space at the top and an exhaust port to facilitate the discharge of gas, thereby enhancing the mass transfer effect of the reaction. The cage-type final polycondensation reactor of the invention has reasonable structure and can adapt to different requirements of different polycondensation stages, thereby facilitating the smooth progress of the reaction.

Claims

Rights request

A cage-type final polycondensation reactor comprising a sealed transverse cylindrical body having a material inlet (1), a material outlet (2) and an exhaust port (3), and having a cylinder interior A stirring device (4), characterized in that the stirring device (4) comprises a stirring basket and a drive shaft.

2. The cage-type final polycondensation reactor according to claim 1, wherein the stirring basket comprises a stirring basket (100) for low-viscosity materials, a stirring basket (200) for medium-viscosity materials, and Stirring basket for high viscosity materials (300).

3. A cage-type final polycondensation reactor according to any of the preceding claims, characterized in that the mixing basket (100) for low-viscosity materials comprises a plurality of sets of perforated ring disks (101), spokes (102), and inclined blades Blade (103) and bottom ring (104).

4. A cage tray final polycondensation reactor according to any of the preceding claims, characterized in that the agitating basket (200) for medium viscosity material comprises a plurality of sets of mesh discs (201), a bottom ring (202), and an outer ring. (203, 204, 205), spokes (206) and tie rods (207).

5. A cage disc final polycondensation reactor according to any of the preceding claims, characterized in that the mixing basket (300) for high viscosity materials comprises a plurality of sets of coils (301), spokes

(302), axial pull film (303) and bushing (304).

6. A cage disc final polycondensation reactor according to any of the preceding claims, characterized in that the drive shaft inside the cylinder comprises a drive shaft (400) for the reaction zone of low viscosity and medium viscosity materials and for high The drive shaft (500) of the viscosity material reaction zone.

7. A cage tray final polycondensation reactor according to any of the preceding claims, characterized in that a mixing basket (100) for low viscosity materials and a stirring basket for medium viscosity materials

( 200) Driven by a drive shaft ( 400) for low viscosity and medium viscosity materials for agitation.

8. A cage disc final polycondensation reactor according to any of the preceding claims, characterized in that the mixing basket (300) for high viscosity materials is driven by a drive shaft for high viscosity materials

(500) Drive to stir.

9. A cage disc final polycondensation reactor according to any of the preceding claims, characterized in that the drive shaft (400) for the reaction zone of the low viscosity and medium viscosity materials is a hollow shaft with a porous surface.

10. A cage disc final polycondensation reactor according to any of the preceding claims, characterized in that The drive shaft (500) for the reaction zone of the high viscosity material is a hollow shaft with no pores on the surface.

A cage-type final polycondensation reactor according to any one of the preceding claims, wherein the inclined blade has an inclination angle α of 5 to 45 degrees.

A cage-type final polycondensation reactor according to any of the preceding claims, characterized in that the angle of inclination α of the pitched blades is 5-20 degrees.

13. The cage-type final polycondensation reactor according to any one of the preceding claims, wherein the transversely-shaped cylinder has an oblong cross section, and the drive shaft axis is located at a center of a lower circle of the cylinder .

14. A cage tray final polycondensation reactor according to any of the preceding claims, characterized in that the vent (3) is located at the top of the reactor.

15. A cage disc final polycondensation reactor according to any of the preceding claims for use in the preparation of a final polycondensation reaction of polyethylene terephthalate.