CN210477469U

CN210477469U - PTT continuous polymerization pre-crystallization device

Info

Publication number: CN210477469U
Application number: CN201921058789.0U
Authority: CN
Inventors: 贾振宇; 董海良; 王文
Original assignee: Zhejiang Henglan Technology Co Ltd
Current assignee: Zhejiang Hengyi Petrochemical Research Institute Co Ltd
Priority date: 2019-07-08
Filing date: 2019-07-08
Publication date: 2020-05-08
Anticipated expiration: 2029-07-08

Abstract

The utility model discloses a PTT continuous polymerization pre-crystallization device, wherein a slicing pre-crystallization quick-drying structure is arranged in a tank body; the slice pre-crystallization quick-drying structure is as follows: a central column is arranged in the tank body along the axis; a plurality of inner cone baffles are arranged on the central column, the inner cone baffles extend along the conical surface of the right cone, the inner side ends of the inner cone baffles are fixed with the central column, and a gap is formed between the outer side ends of the inner cone baffles and the inner side wall of the tank body; a plurality of outer cone baffles are arranged on the inner side wall of the tank body, the outer cone baffles extend along the inverted cone-shaped conical surface, the outer side end of each outer cone baffle is fixed with the inner side wall of the tank body, and a gap is formed between the inner side end of each outer cone baffle and the central column; the inner cone baffles and the outer cone baffles are arranged in a staggered manner in a one-to-one correspondence manner in the height direction. The utility model has the advantages that: the combined type valley-current phase change energy storage device has the advantages of compact structure, capability of greatly compressing the energy conversion and heat transfer process, convenience in production, packaging, transportation and assembly, capability of being combined and designed into various types and specifications, and good popularization significance for the phase change energy storage industry.

Description

PTT continuous polymerization pre-crystallization device

Technical Field

The utility model relates to a chemical fiber production facility field specifically is a PTT continuous polymerization pre-crystallization device.

Background

Polytrimethylene terephthalate (PTT) is a novel aromatic polyester material with excellent performance developed at the end of the 20 th century. Compared with PET and PBT, the special 'odd carbon effect' of the PTT material enables the PTT material to have a unique spiral structure and very good elasticity, and the PTT material has the softness of nylon, the bulkiness of acrylic fibers and the stain resistance of terylene, is easy to dye and has antistatic property, and is widely applied to the fields of clothing, industry, decoration, engineering plastics and the like due to excellent PTT performance. The crystallization property of the PTT is between that of PBT and PET, and because the glass transition temperature of the PTT is very low by 25-65 ℃, the PTT needs to be subjected to pre-crystallization treatment during industrial production and application, so that the problem of agglomeration in the drying process is prevented. The common pre-crystallizer mainly comprises a mechanical stirring type and a fluidized bed type.

Chinese patent document CN2540269Y discloses a "low-melting-point polyester chip pre-crystallization device" on 3/19/2003, which is a typical mechanical stirring type. The scheme comprises a cylinder, a motor, a speed reducer and a conical end enclosure; the output shaft of the motor is connected with the input shaft of the speed reducer, the motor and the speed reducer are supported on the barrel flat cover by the bracket, and the barrel flat cover is fixedly connected with the barrel through the flange; the conical sealing head is provided with a plurality of holes and is fixedly connected with the cylinder body in a welding way; the stirring shaft is arranged in the cylinder body, a plurality of stirring fins are arranged on the stirring shaft, the lower part of the stirring shaft extends into the conical seal head, and the upper end of the stirring shaft penetrates through the flat cover of the cylinder body and is connected with an output shaft of the speed reducer through a coupling.

The mechanically agitated pre-crystallizer was jacketed and the rod-shaped stirring blades rotated to mix the slices uniformly. If the mechanical stirring type pre-crystallizer is used for pre-crystallizing PTT slices, the PTT slices discharged from the granulator are easy to bond, the slices entering the mechanical stirring type pre-crystallizer are easy to bond if the moisture content is small, and a larger heat exchange area or heat exchange strength is required if the moisture content is large. The mechanical stirring type pre-crystallizer is heated by a heat jacket medium, the heating area of the jacket cannot be adjusted, and the temperature of the heat medium is not easy to adjust, so that the adaptability to feeding slices is insufficient. Before the mechanical stirring type pre-crystallizer starts to feed, 1/3-1/2 slices with the volume of the cylinder body are required to be filled in advance to prevent bonding and improve heat transfer efficiency, and the designed heat transfer effect can be achieved only after the slices are fully filled in the cylinder body of the pre-crystallizer. Because the stirring blades are mostly in a steel bar shape, uniform heating cannot be realized due to the characteristics of the sliced particles, so that the retention time of the sliced particles is not uniform; furthermore, the heat conduction and heat transfer efficiency between solid particles is low, and the temperature of sliced particles is also easy to be uneven, so that the crystallinity of the sliced particles is uneven. The mechanical stirring type pre-crystallizer also needs a heating medium supply and circulating system, and the operation is complex.

Chinese patent document CN101210772A discloses "a method for drying PTT chips in PTT/PET composite fully-drawn low-elastic network yarn" at 2008, 7/2, which is a typical fluidized bed type. The PTT slices of the scheme adopt the following drying method: the first step, screening: the PTT sliced raw material passes through a bin → a vibrating screen → a pulse generator → another bin; step two, pre-crystallization: from the other bunker → the vibration feeder → the fluidized bed → the drying tower, the PTT slices stay in the fluidized bed pre-crystallizer for 5 to 15 minutes to complete the pre-crystallization process; step three, drying: after 4-6 hours of high-temperature drying and air drying, the water content of the PTT slices which are uniformly crystallized reaches the standard. The drying method of the invention ensures that the PTT dry slices are crystallized uniformly, have normal hue and do not have the phenomenon of yellowing and degradation; the water content of the slice is below 50ppm, the production and drying process requirements of the PTT-POY pre-oriented yarn are met, and the requirements of composite spinning with PET are met. The PTT dry slice spinning is stable without filament floating.

The boiling fluidized bed type pre-crystallizer is not suitable for materials with high water content and easy caking and agglomeration. PTT slices from the granulator are easy to bond after being dried, and directly enter a pre-crystallizer without being dried, so that the water content is higher. Meanwhile, large wind hot wind circulation is needed for maintaining the fluidization state of the slices, the energy consumption is high, and the slice particles are easy to collide at high speed.

Disclosure of Invention

Based on above problem, the utility model provides a PTT continuous polymerization is crystallization device in advance makes short, the adaptability good of precrystallization and dry flow, under the prerequisite that satisfies the technological requirement, reduces the investment, practices thrift the energy consumption, the simplified operation.

In order to realize the purpose of the invention, the utility model adopts the following technical scheme: a PTT continuous polymerization pre-crystallization device comprises a cylindrical tank body, wherein the tank body is longitudinally sealed, a feed inlet is formed in the upper end of the tank body, a discharge outlet is formed in the lower end of the tank body, a steam inlet is formed below the side wall of the tank body, a steam outlet is formed above the side wall of the tank body, and a slicing pre-crystallization quick-drying structure is arranged between the height of the steam inlet and the height of the steam outlet in the tank body; the slice pre-crystallization quick-drying structure is as follows: a central column is arranged in the tank body along the axis; a plurality of inner cone baffles are arranged on the central column, the inner cone baffles extend along the conical surface of the right cone, the inner side ends of the inner cone baffles are fixed with the central column, and a gap is formed between the outer side ends of the inner cone baffles and the inner side wall of the tank body; a plurality of outer cone baffles are arranged on the inner side wall of the tank body, the outer cone baffles extend along the inverted cone-shaped conical surface, the outer side end of each outer cone baffle is fixed with the inner side wall of the tank body, and a gap is formed between the inner side end of each outer cone baffle and the central column; the inner cone baffles and the outer cone baffles are arranged in a staggered manner in a one-to-one correspondence manner in the height direction.

The PTT continuous polymerization pre-crystallization device designed by the technical scheme is applied to a PTT continuous polymerization pre-crystallization process, and the process comprises the steps of slicing, rough filtering, pre-crystallization, drying and screening. The chip selection is the pelleter, and the PTT piece that the pelleter cut out mixes together with a large amount of water, can't directly carry out the precrystallization of next step, consequently carries out the coarse filtration through pelleter water strainer after the piece to get rid of most water, alleviate the operating pressure of the drying step of follow-up. The wet PTT chips are then fed to a pre-crystallization unit where the pre-crystallization and drying steps are completed simultaneously to improve efficiency. The feeding device for feeding the PTT chips into the pre-crystallization device can generally select a rotary feeding valve and the like. After the PTT slices are discharged from the pre-crystallization device, pre-crystallization and drying are already realized, only the PTT slices need to be sent to a vibrating screen for screening, defective products are removed, and the good products can be stored and put in storage or directly sent to subsequent processing steps. If directly settle the shale shaker in the discharge end of crystallization device in advance, the discharge end of crystallization device in advance can install gyration bleeder valve, firstly plays sealed effect as the discharge gate, secondly can control ejection of compact speed. In the process, the core equipment is the PTT continuous polymerization pre-crystallization device, the main structure of the device is a vertically arranged round tank, the tank body is sealed, the upper end is used for feeding and the lower end is used for discharging, the lower end of the side wall of the tank body is used for introducing steam, and the upper end is used for discharging steam. A central column is arranged in the tank body in the middle, extends along the axial direction of the tank body, and is arranged between the steam inlet and the steam outlet in height. The outer side wall of the central column is fixed with a plurality of inner cone baffles, the inner cone baffles extend along the conical surface of the right cone, the inner side end is high, the outer side end is low, the inner side end is connected with the side wall of the central column, the outer side end is a free end, a gap is formed between the outer side end and the inner side wall of the tank body, and the gap can be used for steam to go upwards and materials to go downwards. Correspondingly, a plurality of outer cone baffles are also fixed on the inner side wall of the tank body, the outer cone baffles extend along the inverted cone-shaped conical surface, the outer end is higher than the inner side end and lower than the inner side end, the outer end is connected with the inner side wall of the tank body, the inner side end is a free end, a gap is formed between the inner end and the outer side wall of the central column, and the gap can be used for steam to go upwards and materials to go downwards. The inner cone baffles and the outer cone baffles are arranged in a staggered mode in the height direction, the inner cone baffles are generally the highest, and the outer cone baffles are generally the lowest. The inner cone baffle and the outer cone baffle can be made of materials with stable chemical shape and enough rigidity, such as stainless steel. In the structure, the materials fall under the driving of gravity from the upper part, and the materials sequentially pass through the staggered inclined planes formed by the inner cone baffle and the outer cone baffle in the falling process, so that the free falling is changed into the step-by-step sliding, and the falling speed is obviously delayed. And in the falling process of the material, the material and steam rising below the material are subjected to countercurrent and cross-flow heat exchange to realize the pre-crystallization and drying of the slices. The slices are in a semi-fluidized state in the process, full contact with steam is realized, strong mixing and dispersion are realized between gas and solid, the heat exchange efficiency is high, the temperature of the slices is uniform, and uneven crystallization is avoided. The conical surface design of baffle can make the material flow along the baffle upper surface steadily, does not have the high-speed collision of cutting grain, can prevent the caking of material. The pre-crystallization device can complete two steps of pre-crystallization and drying at one time, thereby compressing the process flow, shortening the process time, reducing the occupied space of equipment, improving the process efficiency and saving the equipment cost and the process cost.

Preferably, the central column is a circular hollow tube, the upper end of the central column is closed, and the lower end of the central column is opened outside the tank body and is communicated with a steam source; the hollow pipe is provided with a plurality of turbulent flow holes penetrating through the pipe wall. This scheme is the hollow tube with the center post definition, and the lower extreme extends to the jar external, is connected with steam air supply, and the upper end is confined, and it has the vortex hole to open on the lateral wall of hollow tube, and steam is by the blowout of vortex hole, and closely lasting disturbance material flows, makes the material dry more abundant, and the pre-crystallization effect is better. In practical application, the steam inlet and the steam inlet amount in the hollow pipe can be adjusted to obtain the optimal process matching effect according to the process requirements.

Preferably, the turbulent flow holes are divided into a plurality of groups, and one group is arranged below the root part of each inner cone baffle plate; the baffle holes in each group are uniformly distributed on the circumference of the cross section of the central pipe. The location of the baffle openings is particularly critical, preferably in the form of a ring below the base of the respective inner cone baffle. Arrange the vortex hole in this position, the air current receives the restriction of interior cone baffle, forms the slope air current direction of outside downwards, and follow this interior cone baffle upper surface landing's material, continues to receive the vortex of spun steam in the vortex hole when terminal whereabouts, through adjusting vortex steam flow, can change the upper surface sliced flow velocity and the direction of falling to below outer cone baffle, makes to be in the semi-fluidized state, helps the dispersion, the pre-crystallization and the drying of material.

Preferably, an annular gap is formed between the outer end of the inner cone baffle and the inner side wall of the tank body with the same height, and the area of the gap is S1; an annular gap is formed between the inner side end of the outer cone baffle and the outer side wall of the central column with the same height, and the area of the gap is S2; the cross section area of the steam inlet is S3, 20 × S3 is not less than S1 is not less than 50 × S3, 10 × S3 is not less than S2 is not less than 40 × S3. The areas of S1 and S2 are narrow positions of a flow passage through which the materials pass and positions through which the steam passes when rising, and the positions are areas where the materials and the steam are mixed and dispersed most intensely. The falling speed of the slices can be conveniently adjusted by adjusting the flow of the rising steam, so that the size of the area has obvious influence on the pre-crystallization and drying effects of the materials. The above parameters are the optimum value ranges obtained by the inventor according to the process requirements and combining a plurality of experiments.

Preferably, the upper end of the central column is an upward-convex arc top, and the feed inlet is positioned right above the arc top. The material is by the feed inlet free fall, just in time falls the arc top of center post upper end, can rely on self gravity homodisperse, need not to dispose the material deconcentrator again, has practiced thrift the cost, has reduced the equipment quantity.

Preferably, the lower end of the tank body is in an inverted cone shape, and the discharge hole is positioned at the end part of the inverted cone shape; the side wall of the inverted cone-shaped tank body is provided with a bottom steam inlet. After the material passes through the slicing pre-crystallization quick-drying structure above the upper part, most of pre-crystallization and drying are completed, then the material falls into the lower end of the inverted cone-shaped tank body, then the material stays at the lower end of the tank body for a period of time, and steam is continuously introduced from the steam inlet at the bottom during the stay period so as to help the material to complete final pre-crystallization and drying. The residence time is at the discretion of the person skilled in the art according to the process requirements.

Preferably, the number of the bottom steam inlets is a plurality of the bottom steam inlets, and the bottom steam inlets are uniformly distributed on the side wall of the inverted cone-shaped tank body along the circumference. The design ensures the uniformity of steam distribution and can avoid the occurrence of particle bridging phenomenon.

Preferably, the inner side of the steam inlet is connected with a steam distributor, the steam distributor is in a ring pipe type or a straight pipe type, and the lower part of the steam distributor is provided with a groove or a hole. The steam is sprayed out from the slots or the openings at the lower part of the steam distributor and can be uniformly distributed in the cylinder body.

Preferably, the included angle between the generatrix of the cone where the inner cone baffle and the outer cone baffle are located and the horizontal direction is 20-55 degrees. The inclination of the inner cone baffle and the outer cone baffle determines the sliding speed of the material on the inclined upper surface of the material, influences the acting time of the material and upward steam, and influences the dryness and the crystallinity of the material.

Preferably, the roughness Ra of the upper surfaces of the inner cone baffle and the outer cone baffle is less than or equal to 0.8. The upper surfaces of the inner cone baffle and the outer cone baffle are smooth, so that the materials are prevented from being stuck on the upper surfaces by static friction force and cannot slide down.

Preferably, the side wall of the tank body is provided with a plurality of cleaning holes; each cleaning hole is divided into a plurality of layers in the height direction, each layer comprises at least 3 cleaning holes which are uniformly distributed along the circumference; the cleaning holes on the same layer are positioned between the heights of the inner cone baffle and the outer cone baffle of the adjacent group at the opening position on the inner side of the tank body. When necessary, an operator can manually clean the inner cone baffle and the outer cone baffle in the tank body from the outside of the tank body.

Preferably, each cleaning hole is provided with a sight glass. An operator can monitor the operation condition in the tank body at any time through the sight glass, and necessary treatment measures can be taken in time when the operator finds abnormality.

To sum up, the beneficial effects of the utility model are that: the pre-crystallization and drying processes are short and have good adaptability, and on the premise of meeting the process requirements, the investment is reduced, the energy consumption is saved, and the operation is simplified.

Drawings

Fig. 1 is a schematic structural view of a pre-crystallization apparatus according to the present invention.

FIG. 2 is a route diagram of a PTT continuous polymerization and pre-crystallization process to which the present invention is applied.

Wherein: the device comprises a granulator A, a discharge hopper B, a granulator C pre-separator, a granulator D water strainer, a rotary feed valve E, a pre-crystallization device F, a rotary discharge valve G and a vibrating screen H; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13 cleaning holes;

in the figure, the flow of steam is shown by the dashed arrows, and the flow of material is shown by the solid arrows.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and the detailed description.

The embodiment shown in FIG. 1 is a PTT continuous polymerization and pre-crystallization device, which is applied to a continuous production line of 3 ten thousand tons/year PTT polyester of a certain PTT production enterprise.

The pre-crystallization device is provided with a cylindrical tank body 1 which is longitudinally arranged and sealed. Jar body upper end is the arc top, and the top is equipped with feed inlet 2 placed in the middle, and the lower extreme is the back taper, and the bottom of back taper is equipped with discharge gate 3. The below right side of jar body lateral wall is equipped with steam inlet 4, and the top right side is equipped with steam outlet 5.

A slice pre-crystallization quick-drying structure is arranged between the height of the steam inlet and the height of the steam outlet in the tank body. The slice pre-crystallization quick-drying structure is characterized in that a central column 6 is arranged in a tank body along an axis; a plurality of inner cone baffles 7 are arranged on the central column, the inner cone baffles extend along the conical surface of the right cone, the inner side ends of the inner cone baffles are fixed with the central column, and a gap is formed between the outer side ends of the inner cone baffles and the inner side wall of the tank body; a plurality of outer cone baffles 8 are arranged on the inner side wall of the tank body, the outer cone baffles extend along the inverted cone-shaped conical surface, the outer side end of each outer cone baffle is fixed with the inner side wall of the tank body, and a gap is formed between the inner side end of each outer cone baffle and the central column; the inner cone baffles and the outer cone baffles are arranged in a staggered manner in a one-to-one correspondence manner in the height direction. The central column is a circular hollow tube, the upper end of the central column is closed, an upward convex arc top is arranged on the central column, and the arc top is positioned under the feeding hole. The lower end of the hollow pipe is opened outside the left side of the tank body and is communicated with a steam source; the hollow pipe is provided with a plurality of turbulent flow holes penetrating through the pipe wall. In the embodiment, the turbulent flow holes are divided into a plurality of groups, and one group is respectively arranged below the root part of each inner cone baffle plate; the baffle holes in each group are uniformly distributed on the circumference of the cross section of the central pipe. An annular gap is formed between the outer end of the inner cone baffle and the inner side wall of the tank body with the same height, and the area of the gap is S1; an annular gap is formed between the inner side end of the outer cone baffle and the outer side wall of the central column with the same height, and the area of the gap is S2; the cross section area of the steam inlet is S3, 20 × S3 is not less than S1 is not less than 50 × S3, 10 × S3 is not less than S2 is not less than 40 × S3. The values of this example are: s1=35 × S3, S2=25 × S3.

The inner cone baffle and the outer cone baffle are made of stainless steel plates, the included angle between the generatrix of the cone where the inner cone baffle is located and the horizontal direction is 25 degrees, and the included angle between the generatrix of the cone where the outer cone baffle is located and the horizontal direction is 25 degrees. The upper surfaces of the inner cone baffle and the outer cone baffle are polished to ensure that the roughness Ra is less than or equal to 0.8.

The side wall of the inverted cone-shaped tank body is provided with 8 bottom steam inlets 10, and the bottom steam inlets are uniformly distributed on the side wall of the inverted cone-shaped tank body along the circumference. The side wall of the inverted cone-shaped tank body is also provided with a manhole 12 for the maintainers to go in and out of the tank body.

The inner side of the steam inlet is connected with a steam distributor 11, in this example, the steam distributor is a ring pipe type, and the lower part of the steam distributor is provided with a plurality of small holes at equal intervals, so that steam can be uniformly distributed in the tank body after entering.

A plurality of cleaning holes 13 are arranged on the side wall of the tank body; each cleaning hole is divided into a plurality of layers in the height direction, in the embodiment, each layer comprises 3 cleaning holes which are uniformly distributed along the circumference; the cleaning holes on the same layer are positioned between the heights of the inner cone baffle and the outer cone baffle of the adjacent group at the opening position on the inner side of the tank body. Each cleaning hole is provided with a sight glass. An operator can observe the flowing condition of materials in the tank body through the sight glass, and can clean the inner cone baffle and the outer cone baffle at the positions through the cleaning holes when necessary, so that the materials are prevented from being accumulated.

The PTT continuous polymerization pre-crystallization process of the embodiment is applied, and the flow is as follows: PTT slices cut out from the granulator A pass through a discharge hopper B and a granule pre-separator C, most of water is filtered by a water coarse filter D of the granulator, and the PTT slices are sent to a pre-crystallization device F through a rotary feed valve E for pre-crystallization and drying; the PTT that accomplishes the pre-crystallization and is dry is cut grain and is sent into shale shaker H by the gyration bleeder valve G that can adjust discharge speed, and the qualified eager grain of screening is sent into the section feed bin through pneumatic transport and is stored.

In the pre-crystallization device, wet water-containing slices fall down from top to bottom, slide down step by step along the stepped slopes of the inner cone baffle and the outer cone baffle in the midway, and generate strong countercurrent and cross-flow heat exchange with steam from bottom to top in the process of sliding down, so that the slices are pre-crystallized and dried; in the process, the slices are in a semifluidized state, full contact with steam is realized, strong mixing and dispersion are realized between gas and solid, the heat exchange efficiency is high, the temperature of the slices is uniform, and uneven crystallization is avoided. Meanwhile, steam from the hollow pipe is sprayed out, so that the effects of enhancing heat exchange and influencing the flow rate of the slices are achieved. The water content of the slices can be well adapted to the change by adjusting the flow rate and the temperature of the water vapor. When the slices fall to the lower end of the inverted cone-shaped tank body, the slices stay for 20 minutes again, and are further dried by steam, and the phenomena of agglomeration, bridging and the like can be avoided. Finally, steam is discharged from a steam outlet at the upper part, and the dried slices are discharged from a discharge hole through a discharge rotary valve G at the lower part of the tank body.

In this case, the temperature of the steam introduced into the tank of the pre-crystallization apparatus was controlled at 160 ℃ and the crystallinity of the PTT chips pre-crystallized and dried by the pre-crystallization apparatus was 60% or more.

Claims

1. A PTT continuous polymerization pre-crystallization device comprises a cylindrical tank body (1), and is characterized in that the tank body is longitudinally sealed, a feed inlet (2) is formed in the upper end of the tank body, a discharge outlet (3) is formed in the lower end of the tank body, a steam inlet (4) is formed below the side wall of the tank body, a steam outlet (5) is formed above the side wall of the tank body, and a slice pre-crystallization quick-drying structure is arranged between the height of the steam inlet and the height of the steam outlet in the; the slice pre-crystallization quick-drying structure is as follows: a central column (6) is arranged in the tank body along the axis; a plurality of inner cone baffles (7) are arranged on the central column, the inner cone baffles extend along the conical surface of the right cone, the inner side ends of the inner cone baffles are fixed with the central column, and a gap is formed between the outer side ends of the inner cone baffles and the inner side wall of the tank body; a plurality of outer cone baffle plates (8) are arranged on the inner side wall of the tank body, the outer cone baffle plates extend along the inverted cone-shaped conical surface, the outer side ends of the outer cone baffle plates are fixed with the inner side wall of the tank body, and a gap is formed between the inner side ends of the outer cone baffle plates and the central column; the inner cone baffles and the outer cone baffles are arranged in a staggered manner in a one-to-one correspondence manner in the height direction.

2. The PTT continuous polymerization precrystallization apparatus as claimed in claim 1, wherein the central column is a circular hollow tube, the upper end of which is closed, and the lower end of which is open outside the tank body and is communicated with a steam gas source; the hollow pipe is provided with a plurality of turbulent flow holes (9) which run through the pipe wall.

3. The PTT continuous polymerization precrystallization apparatus as claimed in claim 2, wherein the turbulating holes are divided into a plurality of groups, one group being disposed below the root of each inner cone baffle; the baffle holes in each group are uniformly distributed on the circumference of the cross section of the central pipe.

4. The apparatus for continuously polymerizing and pre-crystallizing PTT as recited in claim 2 or 3, wherein an annular gap is formed between the outer end of the inner conical baffle and the inner side wall of the vessel having the same height, and the area of the gap is S1; an annular gap is formed between the inner side end of the outer cone baffle and the outer side wall of the central column with the same height, and the area of the gap is S2; the cross section area of the steam inlet is S3, 20 × S3 is not less than S1 is not less than 50 × S3, 10 × S3 is not less than S2 is not less than 40 × S3.

5. The continuous PTT polymerizing and pre-crystallizing device as recited in claim 1, 2 or 3, wherein the upper end of the central column is an upwardly convex dome, and the feed port is located directly above the dome.

6. The continuous PTT polymerization and recrystallization device as claimed in claim 1, 2 or 3, wherein the lower end of the tank body is in the shape of an inverted cone, and the discharge port is located at the end of the inverted cone; the side wall of the inverted cone-shaped tank body is provided with a bottom steam inlet (10).

7. The continuous PTT polymerizing and pre-crystallizing device as recited in claim 6, wherein the number of the bottom steam inlets is a plurality of bottom steam inlets distributed uniformly along the circumference of the side wall of the inverted cone-shaped tank.

8. The continuous PTT polymerizing and precrystallizing device as defined in claim 1, 2 or 3 wherein the inside of the steam inlet is connected to a steam distributor (11) which is in the form of a ring or straight pipe and has a groove or opening at its lower part.

9. The continuous PTT polymerizing and pre-crystallizing device as recited in claim 1, 2 or 3, wherein the included angle between the generatrix of the cone where the inner cone baffle and the outer cone baffle are located and the horizontal direction is 20-55 °.

10. The continuous PTT polymerizing and precrystallizing apparatus according to claim 1, 2 or 3, wherein the roughness Ra of the upper surfaces of the inner cone baffles and the outer cone baffles is 0.8 or less.