CN212894539U - Reaction system for producing high molecular weight polyester by continuous melt polycondensation - Google Patents

Abstract

The utility model aims to provide a reaction system for producing high molecular weight polyester by continuous melt polycondensation, which is different from the traditional two-step method, the utility model synthesizes high molecular weight polyester by one-step method, thereby realizing high-purity reaction of esterification reaction, and overcoming the defects of low reaction efficiency and low reactant concentration conversion rate of the traditional reactor; in order to achieve the purpose, the utility model provides a reaction system for producing high molecular weight polyester by continuous melt polycondensation, which provides a novel reaction system and a method for producing high molecular weight polyester by continuous melt polycondensation, which embody the integration of product differentiation, production line flexibility, on-line monitoring technology, environmental protection and energy saving technology and greatly promote the development of industry; the utility model provides a reaction system includes: an esterification reactor, a pre-polycondensation reactor and a final polycondensation reactor; the esterification reactor, the pre-polycondensation reactor and the final polycondensation reaction kettle are connected in sequence through pipelines.

Description

Reaction system for producing high molecular weight polyester by continuous melt polycondensation

Technical Field

The utility model belongs to the polyester synthesis field especially relates to a reaction system of continuous melt polycondensation production high molecular weight polyester.

Background

The traditional method for preparing the polyester with high molecular weight (the polymerization degree is more than or equal to 150) is a two-step process for preparing solid particles with medium molecular weight (the polymerization degree is 30-110) by adopting liquid phase polymerization and then improving the molecular weight of the polyester by adopting a solid phase polycondensation method. With the development and technical progress of the polyester industry, the process and the device for manufacturing high molecular weight polyester by one-step melt polycondensation become large-scale trends.

The traditional liquid phase tackifying process method for manufacturing the medium molecular weight polyester adopts 3-5 reactors which are basically kettle type reaction sections, adopts a mechanical stirrer mode to update a reaction interface and remove reaction byproducts, and has the advantages of low reaction efficiency, large number of reactors, large number of equipment, large equipment volume required by unit output and high operating cost.

CN100415710C discloses a preparation method of ethylene terephthalate, which is a continuous esterification reaction, wherein the reaction temperature is 258-290 ℃, the reaction pressure is 40-120 kPa, and the feeding molar ratio of phthalic acid to ethylene glycol is 1: 1.5-1.9. The esterification reaction device comprises a reaction kettle and an external circulation tube array heater, wherein the reaction kettle is provided with an internal chamber and an external chamber double-chamber structure, and the internal chamber is positioned at the bottom of the kettle. The pipeline connecting port of the reaction kettle, which is connected with the inlet of the external circulation tube array heater, is communicated with the inner chamber, and the pipeline connecting port, which is connected with the outlet of the external circulation tube array heater, is communicated with the outer chamber. The liquid phase material channel communicated with the inner chamber and the outer chamber is an annular channel with a U-shaped section. The raw material inlet is positioned at the inlet of the external circulation tube still heater, the liquid phase reaction product outlet is positioned at the bottom of the kettle and communicated with the inner chamber, and the gas phase outlet is positioned at the top of the kettle. The utility model discloses utilize the pressure that ethylene glycol and moisture content evaporation produced to increase the power that the material circulation flows in the system, can obviously reduce the material molar ratio of throwing of ethylene glycol and terephthalic acid, but its defect that still exists aforementioned synthetic method.

CN104017191A discloses a preparation method of PET resin for bottles, which adopts one-step methods of esterification, melt polycondensation and liquid-phase tackifying to prepare PET high-viscosity melt with the intrinsic viscosity of 0.70-1.00 dL/g, and then the PET high-viscosity melt can be directly injection-molded to prepare bottle blanks or sheets, or cooled, granulated and removed of acetaldehyde to prepare PET resin for bottles. Compared with the existing two-step process of melt polycondensation and solid phase polycondensation, the method omits the procedures of solid phase polycondensation and the like, can reduce equipment investment, shorten the process flow and reduce the production energy consumption, but still has various defects of two-stage synthesis.

How to develop an efficient tower reaction section and a process with shorter residence time becomes a technical problem to be solved urgently.

Disclosure of Invention

An object of the utility model is to provide a reaction system of continuous melt polycondensation production high molecular weight polyester, be different from traditional two-step method, the utility model discloses the synthetic high molecular weight polyester of one-step method to the realization is to esterification reaction's high purity reaction, with the defect that the reaction efficiency that solves traditional reactor existence is low and reactant concentration conversion rate is low.

In order to achieve the above object, the utility model provides a reaction system of continuous melt polycondensation production high molecular weight polyester, the utility model provides a reaction system and method of novel, continuous melt polycondensation production high molecular weight polyester has embodied product differentiation, production line flexibility, on-line monitoring technique, environmental protection and energy-conserving technological integration, the very big development that promotes the trade.

The utility model provides a reaction system includes: an esterification reactor, a pre-polycondensation reactor and a final polycondensation reactor; the esterification reactor, the pre-polycondensation reactor and the final polycondensation reaction kettle are sequentially connected through pipelines;

the esterification reactor is a secondary esterification reactor, a partition board is arranged in the esterification reactor to divide the esterification reactor into a primary reaction kettle and a secondary reaction kettle, and the primary reaction kettle is positioned at the upper part of the secondary reaction kettle;

the primary reaction kettle is internally provided with a nested reaction chamber which comprises a first annular guide cylinder and a first inner chamber cover, wherein the first annular guide cylinder is positioned at the center of the bottom of the primary reaction kettle and is enclosed by the wall of a reaction inner chamber; the first annular guide cylinder, the first inner chamber cover and the inner space of the primary reaction kettle are in a communicated state, and reaction materials can flow in each chamber in a baffling mode; the top of the first-stage reaction kettle is provided with a first exhaust port, and the top of the inner chamber cover is provided with a first exhaust pipe; a discharge pipe is arranged at the bottom of the annular guide cylinder and penetrates through the secondary reaction kettle from top to bottom;

a heating plate is arranged inside the secondary reaction kettle, the discharge pipe penetrates through the secondary reaction kettle, a branch pipe is separated out, the branch pipe introduces materials in the discharge pipe into the secondary reaction kettle to perform secondary esterification reaction, a delivery pump is arranged on the branch pipe and used for controlling the flow of the materials, a first discharge hole is formed in the bottom of the secondary reaction kettle, a second exhaust hole is formed in the side wall of the secondary reaction kettle, a backflow port is formed in the side wall of the secondary reaction kettle, and the backflow port is connected with the branch pipe;

the discharging pipe is connected with the tubular heater, will come from one-level reation kettle's material lets in tubular heater's bottom, tubular heater's side pass through the inlet pipe with one-level reation kettle's lateral wall intercommunication returns the material circulation one-level reation kettle, tubular heater for material in the pipeline provides the heating, makes it satisfy reaction temperature's requirement, the discharging pipe is located the part under the tubular heater is provided with first feed inlet, is used for providing the raw materials in to the reaction system.

Further, the prepolycondensation reactor comprises: the reaction kettle comprises a kettle type reaction section positioned at the bottom, a tower type reaction section positioned at the upper part of the kettle type reaction section, and a heating section positioned in the tower type reaction section, wherein the upper part of the kettle type reaction section is connected with the lower part of the tower type reaction section, and the inner spaces of the kettle type reaction section and the tower type reaction section are communicated;

the kettle type reaction section is internally provided with a nested reaction chamber, which comprises a second annular guide cylinder and a second inner chamber cover, wherein the second annular guide cylinder is positioned at the center of the bottom of the kettle type reaction section and is surrounded by the wall of the reaction inner chamber; the second annular guide cylinder, the second inner chamber cover and the inner space of the kettle type reaction section are in a communicated state, reaction materials can flow in each chamber in a baffling mode, a second discharge hole is formed in the bottom of the second annular guide cylinder, and a third exhaust hole is formed in the side wall of the shell of the kettle type reaction section;

the tower reaction section comprises a plurality of layers of circulation trays arranged in the radial direction of a central shaft and a degassing pipe positioned on the central shaft; the degassing device is characterized in that a plurality of air holes are formed in the body of the degassing pipe, adjacent circulation tower trays are fixed on the inner wall of the tower type reaction section on one layer, the outer wall of the degassing pipe on the other layer, and a second feeding hole is formed in the side wall of the upper portion of the tower type reaction section.

Further, a third feeding port, a third discharging port and a fourth exhaust port are arranged on the final polycondensation reaction kettle; the third feed port is used for conveying materials from the bottom of the pre-polycondensation reactor to the final polycondensation reaction kettle, the third discharge port is used for discharging the materials from the bottom of the final polycondensation reaction kettle, and the fourth exhaust port is used for discharging gas-phase materials in the final polycondensation reaction kettle.

Further, first discharge gate with the second feed inlet is through the pipe connection who has the delivery pump, the second discharge gate with the third feed inlet is through the pipe connection who has delivery pump and hydroxy acid value detector, the third discharge gate passes through the pipeline and is connected with delivery pump, viscometer and pelleter in proper order.

Further, the third exhaust port and the fourth exhaust port are connected with a spraying system and a vacuum system through pipelines with valves.

Further, the esterification reactor is connected with a raw material preparation system, the raw material preparation system comprises a raw material preparation tank, a slurry pump and a densimeter which are sequentially connected, and the densimeter is connected with the discharge pipe through a pipeline.

Further, the esterification reactor is connected with a separation tower through a pipeline, a fifth exhaust port is arranged at the upper part of the separation tower, a first air inlet is arranged at the middle part of the separation tower, and a fourth discharge port and a fourth feed port are arranged at the lower part of the separation tower; the fifth exhaust port is sequentially connected with the lithium bromide unit, the refractometer and the organic matter recovery device through pipelines, and the organic matter recovery device is connected with a sewage discharge pipeline; the first exhaust port and the second exhaust port are connected with the first air inlet through a steam pipeline; and the fourth discharge hole is connected with the raw material preparation tank through a dihydric alcohol reflux pipeline.

Further, a mixing device and a heater are sequentially arranged on a pipeline connected with the first discharge port and the second feed port, the mixing device comprises more than one monomer pipeline system, and one monomer pipeline system is connected with the heater through a pipeline.

Further, monomer pipe-line system includes delivery pump, hydroxy acid value detector and the blender that connects gradually through the pipeline, the blender includes dynamic mixer and the static mixer of front and back connection, delivery pump with through the pipeline connection between the first discharge gate.

Further, the pre-polycondensation reactor is also connected with a first vacuum spraying system through a pipeline; optionally, a second vacuum spray system may also be included.

Further, the first vacuum spraying system comprises a first spraying condenser, a first receiving groove, a first conveying pump, a first filter and a first condenser which are sequentially connected end to end through pipelines; the third gas vent pass through vacuum gas phase pipeline with first spray the condenser and be connected, the pipeline between first delivery pump and the first filter passes through the dihydric alcohol backflow pipeline and is connected gradually with third filter, turbidity appearance and fourth feed inlet, first spray the condenser and pass through vacuum pump line connection.

Further, the second vacuum spraying system has the same structure as the first vacuum spraying system and comprises a second spraying condenser, a second receiving tank, a second delivery pump, a second filter and a second condenser which are sequentially connected end to end through pipelines; and the second spraying condenser is connected with the final polycondensation reaction kettle and is used for recovering and treating gas-phase materials generated by the final polycondensation reaction kettle.

Further, a pipeline between the second filter and the second condenser is connected with the first receiving tank through a dihydric alcohol pipeline, and is used for recycling the dihydric alcohol material recovered from the final polycondensation reaction kettle.

Further, the fourth exhaust port is connected with the second spray condenser through a vacuum gas phase pipeline, the second spray condenser outputs polyester melt through a vacuum pump pipeline, and the second receiving tank is connected with a fresh dihydric alcohol replenishing pipeline and used for timely replenishing fresh dihydric alcohol materials to the reaction system when the recovered dihydric alcohol is insufficient.

The beneficial effects of the utility model reside in that:

1. the utility model provides an esterification reactor, a pre-polycondensation reactor, a complete system for reaction, separation, energy recovery, on-line detection and environmental protection, which improves the conversion rate of reaction products, provides a production process and a method of products with high polymerization degree, and can accurately control the product quality;

2. the system method of the utility model contains the content of the flexible production line, and can be used for the production of various differential products and the recovery and the reutilization of energy and byproducts.

Drawings

FIG. 1 is a schematic view of a reaction system for producing high molecular weight polyester by continuous melt polycondensation according to the present invention;

fig. 2 is a schematic view of a first vacuum spraying system provided by the present invention;

fig. 3 is a schematic view of a second vacuum spraying system provided by the present invention;

FIG. 4 is a schematic diagram of an esterification reactor provided by the present invention;

FIG. 5 is a schematic view of a pre-polycondensation reactor provided by the present invention;

fig. 6 is a schematic view of a separation column provided by the present invention.

As shown in the figure, 10-raw material preparation tank, 11-slurry pump, 12-densitometer, 20-esterification reactor, 201-first exhaust port, 202-first exhaust pipe, 203-second exhaust port, 204-first discharge port, 205-first feed port, 21-tubular heater, 22-separation column, 221-first intake port, 222-fourth discharge port, 223-fourth feed port, 224-fifth exhaust port, 23-refractometer, 30-prepolycondensation reactor, 301-second feed port, 302-circulation tray, 303-degassing pipe, 304-third exhaust port, 305-second discharge port, 31-mixer, 32-heater, 40-final polycondensation reactor, 50-first vacuum spray system, 501-first spray condenser, 502-a first receiving tank, 503-a first delivery pump, 504-a first filter, 505-a first condenser, 60-a second vacuum spraying system, 601-a second spraying condenser, 602-a second receiving tank, 603-a second delivery pump, 604-a second filter, 605-a second condenser, 73-a third filter, 74-a turbidimeter, 80-an organic matter recovery device, and 90-a lithium bromide unit.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the drawings in the embodiments of the present invention are combined below to clearly and completely describe the technical solutions in the embodiments of the present invention.

Example 1

A method for synthesizing bottle-grade copolyester, wherein the degree of polymerization of the bottle-grade copolyester is DP150, the yield of polymer is 12500kg/h, and the preparation method comprises the following steps:

I. esterification reaction:

uniformly mixing terephthalic acid (PTA) and Ethylene Glycol (EG) at the molar ratio of 1:1.8 of alkyd at 60 ℃ to obtain slurry, introducing the slurry into a tubular heater 21 through a screw pump according to the flow rate of 17980kg/h to continuously heat the slurry, and discharging the slurry from the tubular heater 21 to the temperature of 262 ℃; introducing the heated slurry into an esterification reactor 20 for esterification reaction, wherein the temperature in a first-stage reaction kettle is 260 ℃, the pressure is 70KPa, the temperature in a second-stage reaction kettle is 265 ℃, the pressure is 0.0KPa, the residence time of the slurry in the esterification reactor 20 is 3.0 hours in total, the esterification rate of an esterification reaction product obtained after the reaction at an outlet is 98.2%, the polymerization degree is DP 5-10, and the acid value is 35-45mg KOH/g, the obtained esterification product enters a monomer pipeline from a first discharge port 204, and a monomer is provided for a required process according to subsequent requirements, wherein one pipeline guides the esterification reaction product into a heater 32 to be heated, and then guides the esterification reaction product into a pre-polycondensation reactor 30; wherein, the gas phase flow rate generated in the esterification reactor 20 is 7290.0kg/h, and the gas phase flow rate enters the separation tower 22 from the top of the esterification reactor 20 through a pipeline, wherein the ethylene glycol returns to the raw material preparation tank at the flow rate of 4997.0kg/h, and the water separated by the separation tower 22 is discharged at the flow rate of 2293.0 kg/h; leading out the reaction material in the first-stage reaction kettle from a discharge pipe at the bottom of the first-stage reaction kettle of the esterification reactor 20 to a tubular heater 21 through a second-stage reaction kettle, and adding 3.75kg/h of catalyst antimony trioxide into the material through a branch on a leading-out pipeline, wherein the content of antimony in the reaction product is 180 ppm;

optionally, adding a toner (an redness agent and/or a blueness agent) in an amount of 20-50ppm by weight of terephthalic acid (PTA);

II. Pre-polycondensation reaction:

the reaction material from the first discharge port 204 of the second-stage reaction kettle enters the pre-polycondensation reactor 30 through a pipeline, a branch pipe inlet is arranged on the pipeline, ethylene glycol isophthalate is added into the pipeline, the added flow rate is 325.0kg/h, the mixed material is uniformly mixed by a dynamic mixer and/or a static mixer arranged on the pipeline, then enters a heater 32 to be heated to 283 ℃ and enters the pre-polycondensation reactor 30, an esterification reactant enters from the top of the pre-polycondensation reactor 30, flows through 20 pairs of trays in a tower reaction section, and is subjected to pre-polycondensation reaction under the conditions of 280 ℃ and 2400Pa (absolute pressure), ethylene glycol gas removed from each layer of trays is pumped into a degassing pipe 303 positioned on a central shaft and is pumped out along the degassing pipe 303 downwards and is discharged from a third exhaust port 304, and the flow rate is controlled at 480 kg/h; the retention time of the reaction materials in the tower reaction section is 1.0-2.0 hours;

the liquid phase material in the tower reaction section falls from the tower tray layer by layer in a plug flow mode, finally falls into a kettle type reaction section positioned at the lower part of the pre-polycondensation reactor 30, the retention time in the tower reaction section is 2.0-3.0h, the obtained material flows through the second inner chamber cover and the second inner chamber cover through baffling, the reaction is continued, the reacted material is discharged through a second discharge hole 305 positioned at the bottom of the kettle type reaction section and is led to a final polycondensation reaction kettle 40, and the flow control is 12510 kg/h;

III, final polycondensation reaction:

after the reaction materials from the pre-polycondensation reactor 30 enter the final polycondensation reactor 40, the final polycondensation reaction is continued at the reaction temperature of 285 ℃ and the pressure of 120Pa (absolute pressure) (the pre-polycondensation reactor 30 is also provided with an online pressure and/or viscosity detection device, wherein the viscosity detection device is arranged on an outlet pipeline of the final polycondensation reactor 40), and the residence time of the reaction materials in the final polycondensation reactor 40 is 1.5-2.5 hours;

the ethylene glycol steam speed discharged from the final polycondensation reaction kettle 40 is 60.0kg/h, the polymerization degree of the obtained reaction product is DP150, the dynamic viscosity is 120 ten thousand centipoise, the flow rate is 12450kg/h, the discharged final polycondensation product is sent to a granulator for granulation, and before the final polycondensation product is used for bottle-grade packaging preparation, the final polycondensation product is preferably treated by an acetaldehyde stripping device, and the acetaldehyde content in the product is controlled to be less than or equal to 1.0 ppm.

Example 2

A synthetic method of film-grade polyester PET is provided, the degree of polymerization of the film-grade polyester is DP 120, the yield of the polymer is 12500kg/h, and the preparation method comprises the following steps:

I. esterification reaction:

taking terephthalic acid (PTA) and Ethylene Glycol (EG) according to the molar ratio of the alcohol acid being 1:1.6, uniformly mixing at 60 ℃ to obtain slurry, introducing the slurry into a tubular heater 21 through a screw pump according to the flow rate being 17980kg/h to continuously heat the slurry, and enabling the temperature of the slurry discharged from the tubular heater 21 to reach 265 ℃; introducing the heated slurry into an esterification reactor 20 for esterification reaction, wherein the temperature in a first-stage reaction kettle is 260 ℃, the pressure is 50KPa, the temperature in a second-stage reaction kettle is 263 ℃, the pressure is 0.0KPa (gauge pressure), the residence time of the slurry in the esterification reactor 20 is 2.5 hours in total, the esterification rate of an esterification reaction product obtained after the reaction at an outlet is 98.2%, the polymerization degree is DP 5, and the acid value is 45mg KOH/g, the obtained esterification product enters a monomer pipeline from a first discharge port 204, and a monomer is provided for a required process according to subsequent requirements, wherein one pipeline introduces the esterification reaction product into a heater 32 to be heated and then introduces into a pre-polycondensation reactor 30; wherein a gas phase flow rate of 7290.0kg/h generated in the esterification reactor 20 enters the separation tower 22 from the top of the esterification reactor 20 through a pipeline, wherein ethylene glycol returns to the raw material preparation tank 10 at a flow rate of 4997.0kg/h, and water separated by the separation tower 22 is discharged at a flow rate of 2293.0 kg/h; leading out the reaction material in the first-stage reaction kettle from a discharge pipe at the bottom of the first-stage reaction kettle of the esterification reactor 20 to a tubular heater 21 through a second-stage reaction kettle, arranging a branch on a leading-out pipeline, adding 3.75kg/h of ethylene glycol antimony serving as a catalyst into the material, uniformly mixing the material through a dynamic mixer and/or a static mixer arranged on a pipeline according to the content of the antimony in a reaction product of 180ppm, and then leading the material into the tubular heater 21;

II. Pre-polycondensation reaction:

a branch pipe inlet is arranged on a pipeline of a reaction material from a first discharge port 204 of a secondary reaction kettle, ethylene glycol isophthalate is added into the pipeline, the adding flow rate is 325.0kg/h, the mixed material is uniformly mixed by a dynamic mixer and/or a static mixer arranged on the pipeline, then enters a heater 32, is heated to 280 ℃ and then enters a pre-polycondensation reactor 30, an esterification reactant enters from the top of the pre-polycondensation reactor 30, flows through 20 pairs of trays in a tower reaction section, is subjected to pre-polycondensation reaction at 280 ℃ and under the pressure of 3000Pa (absolute pressure), glycol gas removed from each layer of tray is pumped into a degassing pipe 303 positioned on a central shaft and is pumped out, the glycol gas is discharged from a third exhaust port 304 along the downward direction of the degassing pipe 303, and the flow rate is controlled at 480 kg/h; the retention time of the reaction materials in the tower reaction section is 1.0-2.0 hours;

liquid phase materials in the tower type reaction section fall from a tower tray layer by layer in a plug flow mode and finally fall into a kettle type reaction section at the lower part of the pre-polycondensation reactor 30, the materials flow through baffling between a second inner chamber cover and a second inner chamber cover to continue to react, the reacted materials are discharged through a second discharge hole 305 at the bottom of the kettle type reaction section and are led to a final polycondensation reaction kettle 40, and the flow rate is controlled at 12510 kg/h;

III, final polycondensation reaction:

after the reaction material from the pre-polycondensation reactor 30 enters the final polycondensation reactor 40, the final polycondensation reaction is continued at a reaction temperature of 282 ℃ and a pressure of 200Pa (absolute pressure), and the residence time of the reaction material in the final polycondensation reactor 40 is 1.5 to 2.5 hours;

the ethylene glycol steam speed discharged from the final polycondensation reaction kettle 40 is 60.0kg/h, the polymerization degree of the obtained reaction product is DP 120, the dynamic viscosity is 80 ten thousand centipoise, the flow rate is 12450kg/h, and the discharged final polycondensation product is sent to a granulator for granulation and is used for preparing a sheet product of film-grade polyester PET.

It is to be understood that the embodiments described are only some of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

Claims (14)

1. A reaction system for producing high molecular weight polyester by continuous melt polycondensation, comprising: an esterification reactor (20), a pre-polycondensation reactor (30) and a final polycondensation reaction kettle (40); the esterification reactor (20), the pre-polycondensation reactor (30) and the final polycondensation reaction kettle (40) are sequentially connected through pipelines;

the esterification reactor (20) is a secondary esterification reactor (20), a partition board is arranged in the esterification reactor (20) to divide the esterification reactor into a primary reaction kettle and a secondary reaction kettle, and the primary reaction kettle is positioned at the upper part of the secondary reaction kettle;

the primary reaction kettle is internally provided with a nested reaction chamber which comprises a first annular guide cylinder and a first inner chamber cover, wherein the first annular guide cylinder is positioned at the center of the bottom of the primary reaction kettle and is enclosed by the wall of a reaction inner chamber; the first annular guide cylinder, the first inner chamber cover and the inner space of the primary reaction kettle are in a communicated state, and reaction materials can flow in each chamber in a baffling mode; the top of the primary reaction kettle is provided with a first exhaust port (201), and the top of the inner chamber cover is provided with a first exhaust pipe (202); a discharge pipe is arranged at the bottom of the annular guide cylinder and penetrates through the secondary reaction kettle from top to bottom;

a heating plate is arranged inside the secondary reaction kettle, a branch pipe is branched after the discharge pipe passes through the secondary reaction kettle, the branch pipe introduces materials in the discharge pipe into the secondary reaction kettle to perform secondary esterification reaction, a delivery pump is arranged on the branch pipe and used for controlling the flow of the materials, a first discharge hole (204) is arranged at the bottom of the secondary reaction kettle, a second exhaust hole (203) is arranged on the side wall of the secondary reaction kettle, a backflow port is arranged on the side wall of the secondary reaction kettle and connected with the branch pipe;

the discharging pipe is connected with tubular heater (21), will come from one-level reation kettle's material lets in the bottom of tubular heater (21), the side of tubular heater (21) pass through the inlet pipe with one-level reation kettle's lateral wall intercommunication returns the material circulation one-level reation kettle, tubular heater (21) for providing the heating for the material in the pipeline, make it satisfy reaction temperature's requirement, the discharging pipe is located the part under tubular heater (21) is provided with first feed inlet (205) for provide the raw materials in to the reaction system.

2. The reaction system for the continuous melt polycondensation for producing high molecular weight polyester according to claim 1, wherein the prepolycondensation reactor (30) comprises: the reaction kettle comprises a kettle type reaction section positioned at the bottom, a tower type reaction section positioned at the upper part of the kettle type reaction section, and a heating section positioned in the middle of the tower type reaction section, wherein the upper part of the kettle type reaction section is connected with the lower part of the tower type reaction section, and the inner spaces of the kettle type reaction section and the tower type reaction section are communicated;

the kettle type reaction section is internally provided with a nested reaction chamber, which comprises a second annular guide cylinder and a second inner chamber cover, wherein the second annular guide cylinder is positioned at the center of the bottom of the kettle type reaction section and is surrounded by the wall of the reaction inner chamber; the second annular guide cylinder, the second inner chamber cover and the inner space of the kettle type reaction section are in a communicated state, reaction materials can flow in each chamber in a baffling mode, a second discharge hole (305) is formed in the bottom of the second annular guide cylinder, and a third exhaust hole (304) is formed in the side wall of the shell of the kettle type reaction section;

the tower reaction section comprises a plurality of layers of circulation trays (302) arranged in the radial direction of a central shaft and a degassing pipe (303) positioned on the central shaft; the tube body of the degassing tube (303) is provided with a plurality of air holes, adjacent circulation trays (302) are fixed on the inner wall of the tower type reaction section on one layer, the outer wall of the degassing tube (303) on the other layer, and the side wall of the upper part of the tower type reaction section is provided with a second feeding hole (301).

3. The reaction system for producing high molecular weight polyester by continuous melt polycondensation according to claim 2, wherein the final polycondensation reaction vessel (40) is provided with a third inlet, a third outlet and a fourth outlet; the third feeding port is used for conveying materials from the bottom of the pre-polycondensation reactor (30) to the final polycondensation reaction kettle (40), the third discharging port is used for discharging the materials from the bottom of the final polycondensation reaction kettle (40), and the fourth exhaust port is used for discharging gas-phase materials in the final polycondensation reaction kettle (40).

4. The reaction system for the continuous melt polycondensation production of high molecular weight polyester according to claim 3, wherein the first outlet (204) is connected to the second inlet (301) through a line having a transfer pump, the second outlet (305) is connected to the third inlet through a line having a transfer pump and a hydroxy acid meter, and the third outlet is connected to the transfer pump, the viscometer and the cutter through lines in this order.

5. The reaction system for continuous melt polycondensation production of high molecular weight polyester according to claim 3, wherein the third exhaust port (304) and the fourth exhaust port are connected to a shower system and a vacuum system through a line having a valve.

6. The reaction system for continuous melt polycondensation production of high molecular weight polyester according to claim 1, wherein the esterification reactor (20) is connected to a raw material preparation system comprising a raw material preparation tank (10), a slurry pump (11) and a densimeter (12) connected in sequence, and the densimeter (12) is connected to the discharge pipe through a pipeline.

7. The reaction system for continuous melt polycondensation production of high molecular weight polyester according to claim 6, wherein the esterification reactor (20) is connected to the separation column (22) through a pipeline, the separation column (22) is provided with a fifth gas outlet (224) at the upper part, the separation column (22) is provided with a first gas inlet (221) at the middle part, and the separation column (22) is provided with a fourth gas outlet (222) and a fourth gas inlet (223) at the lower part; the fifth exhaust port (224) is sequentially connected with the lithium bromide unit (90), the refractometer (23) and the organic matter recovery device (80) through pipelines, and the organic matter recovery device (80) is connected with a sewage discharge pipeline; the first exhaust port (201) and the second exhaust port (203) are connected to the first inlet port (221) by a steam line; the fourth discharge port (222) is connected to the raw material preparation tank (10) through a glycol return line.

8. The reaction system for producing high molecular weight polyester by continuous melt polycondensation according to claim 4, wherein a mixing device and a heater (32) are sequentially arranged on a pipeline connecting the first discharge port (204) and the second feed port (301), the mixing device comprises more than one monomer pipeline system, and one monomer pipeline system is connected with the heater (32) through a pipeline.

9. The reaction system for producing high molecular weight polyester by continuous melt polycondensation according to claim 8, wherein the monomer piping system comprises a transfer pump, a hydroxy acid value detector and a mixer (31) connected in series via a pipeline, the mixer (31) comprises a dynamic mixer (31) and a static mixer (31) connected in series, and the transfer pump is connected to the first discharge port (204) via a pipeline.

10. The reaction system for the continuous melt polycondensation for producing high molecular weight polyester according to claim 7, wherein the prepolycondensation reactor (30) is further connected to the first vacuum shower system (50) through a line; optionally, a second vacuum spray system (60) may also be included.

11. The reaction system for continuous melt polycondensation production of high molecular weight polyester according to claim 10, wherein the first vacuum spray system (50) comprises a first spray condenser (501), a first receiving tank (502), a first transfer pump (503), a first filter (504), and a first condenser (505) connected end to end in this order through a pipeline; the pre-polycondensation reactor (30) is connected with the first spray condenser (501) through a vacuum gas phase pipeline, a pipeline between the first delivery pump (503) and the first filter (504) is sequentially connected with the third filter (73), the turbidity meter (74) and the fourth feed inlet (223) through a dihydric alcohol reflux pipeline, and the first spray condenser (501) is connected with a vacuum system through a vacuum pump removal pipeline.

12. The reaction system for producing high molecular weight polyester by continuous melt polycondensation according to claim 11, wherein the second vacuum spray system (60) has the same structure as the first vacuum spray system (50) and comprises a second spray condenser (601), a second receiving tank (602), a second delivery pump (603), a second filter (604) and a second condenser (605) which are connected end to end in sequence through pipelines; and the second spray condenser (601) is connected with the final polycondensation reaction kettle (40) and is used for recovering and treating gas-phase materials generated by the final polycondensation reaction kettle (40).

13. The reaction system for continuous melt polycondensation production of high molecular weight polyester according to claim 12, wherein the line between the second filter (604) and the second condenser (605) is connected to the first receiving tank (502) through a glycol line for recycling glycol material recovered in the final polycondensation reaction vessel (40).

14. The continuous melt polycondensation reaction system for producing high molecular weight polyester according to claim 13, wherein the final polycondensation reaction kettle (40) is connected to the second spray condenser (601) through a vacuum gas line, the second spray condenser (601) outputs polyester melt through a vacuum pump line, and the second receiving tank (602) is connected to a fresh glycol replenishment line for replenishing the reaction system with fresh glycol material in time when there is insufficient glycol to be recovered.

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