Polycondensation kettle capable of rapidly devolatilizing

Abstract

The utility model discloses a rapid devolatilization polycondensation kettle which comprises a kettle body, a heating coil and a frame type stirrer are arranged in an inner cavity of the kettle body, a heating jacket is arranged on the periphery of the kettle body, a bottom outlet of the kettle body is connected with an inlet of a polycondensation gear pump, and an outlet of the polycondensation gear pump is connected with a middle inlet of an electric three-way valve through a pipeline. An outlet I of the electric three-way valve is connected with the top center of the film spraying component through a connecting pipe; the film spraying component is positioned at the upper part of the inner cavity of the kettle body and extends along the horizontal direction; and an outlet II of the electric three-way valve is connected with granulator granulation equipment. And a spiral stirring blade which is guided downwards is wound on a central shaft of the frame type stirrer. The rapid devolatilization polycondensation kettle can be used for rapidly devolatilizing and separating out alcohol and tetrahydrofuran in a melt, so that the polycondensation reaction time is shortened, and the viscosity and the productivity of a product are improved.

Description

Technical Field

[0001] The utility model relates to a polymer material production device, in particular to a fast devolatilization polycondensation kettle, belonging to the technical field of polyester production equipment. Background Art

[0002] The frame-type agitator structure used in traditional polycondensation kettles cannot meet the needs of high-viscosity products. The polycondensation reaction is an exothermic reaction. Especially in the later stage of the polycondensation reaction for producing high-viscosity products, the material temperature rise caused by the stirring operation is very obvious. The high temperature can easily cause the side reaction rate to accelerate, which will cause the viscosity of the material to no longer increase, but instead decrease, seriously affecting the quality of the product. If the stirring speed is reduced too low to avoid the material temperature rise caused by the stirring operation, the liquid level of the material in the kettle will not be updated in time, and the small molecules generated by the polycondensation reaction cannot be volatilized and separated in time, affecting the devolatilization effect, and will also cause the side reaction rate to increase, the material viscosity will no longer increase, affecting the quality of the product.

[0003] The existing polycondensation reactor agitator is suitable for producing PET with an intrinsic viscosity below 0.700 dl / g (using analytical reagents, phenol and tetrachloroethane in a ratio of 3:2) and PBT with an intrinsic viscosity below 1.100 dl / g. It cannot meet the requirements for producing PETG products with an intrinsic viscosity of 0.730~0.830 dl / g, and cannot meet the demand for higher product viscosities. Utility Model Content

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and utility model title of this application, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0005] In view of the above problems and / or the problems existing in the prior art, the present utility model is proposed.

[0006] The purpose of the utility model is to overcome the problems existing in the prior art and provide a fast devolatilization polycondensation kettle, which can quickly devolatilize and separate alcohol and tetrahydrofuran in the melt, shorten the polycondensation reaction time, and improve product viscosity and production capacity.

[0007] In order to solve the above technical problems, the utility model provides a rapid devolatilization polycondensation kettle, comprising a kettle body, the inner cavity of the kettle body is provided with a heating coil and a frame agitator, the outer periphery of the kettle body is provided with a heating jacket, the bottom outlet of the kettle body is connected to the inlet of the polycondensation gear pump, the outlet of the polycondensation gear pump is connected to the middle inlet of the electric three-way valve through a pipeline, the outlet one of the electric three-way valve is connected to the top center of the film spraying component through a connecting pipe, the film spraying component is located in the upper part of the inner cavity of the kettle body, extends in the horizontal direction and has a slit-shaped outlet at the bottom; the outlet two of the electric three-way valve is connected to the pelletizer granulation equipment.

[0008] As an improvement of the present invention, the film spraying component is a conical box extending in the horizontal direction, the upper portion is a square cross-section, and the lower portion is an isosceles triangle cross-section with a narrowed bottom.

[0009] As a further improvement of the present invention, a downward-directed spiral stirring blade is wound around the central axis of the frame-type agitator.

[0010] As a further improvement of the present invention, the heat medium pipe at the outlet of the condensation heat medium pump is connected to the heat medium inlet of the heating coil and the heating jacket, and the heat medium outlet of the heating coil and the heating jacket is connected to the inlet of the condensation heat medium pump through a heat medium radiator, and is connected to the primary heat medium return pipe; the primary heat medium supply pipe is connected to the inlet pipe of the condensation heat medium pump through a temperature control regulating valve group.

[0011] As a further improvement of the present invention, the gas phase outlet of the condensation kettle is connected to the inlet of the No. 2 cooler, and the top gas phase outlet of the No. 2 cooler is connected to the inlet of the No. 2 cyclone separator; the bottom liquid phase outlet of the No. 2 cooler and the No. 2 cyclone separator is connected to the inlet of the No. 2 condensation receiving tank; the top balance outlet of the No. 2 cyclone separator is connected to the top balance inlet of the No. 2 condensation receiving tank, the top gas phase outlet of the No. 2 cyclone separator is connected to the inlet of the No. 2 buffer tank, and the top outlet of the No. 2 buffer tank is connected to the inlet of the condensation vacuum pump group.

[0012] As a further improvement of the present invention, the polycondensation vacuum pump group includes three-stage Roots pumps connected in series, and the outlet of the last-stage Roots pump is connected to the inlet of the dry screw pump.

[0013] Compared with the existing technology, the utility model has achieved the following beneficial effects: 1. During the material reaction stage of the polycondensation kettle, the material passes through the polycondensation gear pump and the electric three-way valve, and then self-circulates through the film spraying component. The material coming out of the film spraying component is in a thin film state, and the enlarged material evaporation surface is beneficial to the volatilization and separation of small molecules in the material, accelerates the polycondensation reaction speed, and plays a partial role in the agitator.

[0014] 2. The polycondensation frame agitator structure has been optimized. The agitator ribs on the periphery of the frame agitator are retained to scrape the inner wall of the kettle to refresh the material, preventing prolonged retention of material on the kettle wall and affecting quality. A spiral agitator blade has been designed in the center of the frame agitator, rotating to push the material downward. At the same speed, the new agitator structure achieves a far superior liquid level refreshment effect than traditional frame agitators.

[0015] 3. The secondary heat medium system of the polycondensation kettle system is designed with a heat medium radiator, which can reduce the temperature of the secondary heat medium and is used to remove the excess heat energy generated by the exothermic reaction of the polycondensation kettle, so as to prevent the material from overheating and losing control in a high-viscosity state and reduce the impact of side reactions.

[0016] 4. The polycondensation kettle system uses mechanical vacuum pumps, including dry screw pumps and three-stage Roots pumps. Considering the diversity of products and raw materials, the use of vacuum jet pumps has limitations. One type of injection medium cannot meet diverse needs. Compared with the operating energy consumption, the energy consumption of mechanical vacuum pumps is lower than that of jet vacuum pumps. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. The drawings are only provided for reference and explanation, and are not intended to limit the present invention. Among them:

[0018] Figure 1 This is a working diagram of the polycondensation kettle with rapid devolatilization of the utility model;

[0019] Figure 2 This is an enlarged view of the frame agitator in the polycondensation kettle;

[0020] Figure 3 This is the main view of the film spraying parts in the polycondensation kettle;

[0021] Figure 4 It is a cross-sectional view of the film spraying parts in the polycondensation reactor;

[0022] In the figure: 1. Polycondensation kettle; 1a. Polycondensation heat medium pump; 1b. Temperature control valve group; 1c. Polycondensation gear pump; 1d. Cooler No. 2; 1e. Cyclone separator No. 2; 1f. Polycondensation receiving tank No. 2; 1g. Buffer tank No. 2; 1h. Film spraying components; 1j. Frame agitator; 1k. Spiral agitator blade;

[0023] 2. Polycondensation vacuum pump unit; 3. Heat medium radiator; 4. Viscometer; 5. Pelletizer and granulation equipment;

[0024] G1. Nitrogen pipe; G2. Primary heat medium supply pipe; G3. Primary heat medium return pipe;

[0025] S1. Electric three-way valve. DETAILED DESCRIPTION

[0026] In the following description of the present invention, the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific direction.

[0027] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only a part of the present invention, not all of the embodiments.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] like Figure 1 As shown, the rapid devolatilization polycondensation kettle of the present invention includes a kettle body, the inner cavity of which is equipped with a heating coil and a frame agitator, and the outer periphery of the kettle body is provided with a heating jacket. The feed inlet of the polycondensation kettle 1 is connected to the pre-condensation material pipe, the material outlet of the polycondensation kettle 1 is connected to the inlet of the polycondensation gear pump 1c, and the outlet of the polycondensation gear pump 1c is connected to the inlet of the electric three-way valve S1. The connecting pipe is provided with a viscometer 4. The first outlet of the electric three-way valve S1 is connected to the film spraying component 1h, and the second outlet is connected to the pelletizer granulation equipment 5.

[0030] A nitrogen pipe G1 is connected to the top of the polycondensation reactor 1. The gas phase outlet of the polycondensation reactor 1 is connected to the inlet of the No. 2 cooler 1d. The top gas phase outlet of the No. 2 cooler 1d is connected to the inlet of the No. 2 cyclone separator 1e. The bottom liquid phase outlet of the No. 2 cooler 1d is connected to the inlet of the No. 2 polycondensation receiving tank 1f. The drainage of the No. 2 polycondensation receiving tank 1f is recycled. The bottom liquid phase outlet of the No. 2 cyclone separator 1e is also connected to the top inlet of the No. 2 polycondensation receiving tank 1f. The top balance outlet of the No. 2 cyclone separator 1e is connected to the top balance inlet of the No. 2 polycondensation receiving tank 1f. The top gas phase outlet of the No. 2 cyclone separator 1e is connected to the inlet of the No. 2 buffer tank 1g. The drainage of the No. 2 buffer tank 1g is recycled. The top outlet of the No. 2 buffer tank 1g is connected to the inlet of the polycondensation vacuum pump group 2.

[0031] In view of the problem that the polycondensation kettle in the prior art cannot meet the demand for high viscosity products, the polycondensation kettle has optimized the structure of the frame agitator, retaining the stirring ribs on the periphery of the frame agitator 1j to scrape the material on the inner wall of the kettle to prevent the material from staying on the kettle wall for a long time and affecting the quality; and a spiral stirring blade 1k centered on the axis is designed in the middle of the frame agitator 1j, and the stirring rotates in the form of spiral downward pressing of the material, such as Figure 2 At the same speed, the new structure agitator has a much better effect on material level renewal than the traditional frame agitator.

[0032] A film spraying component 1h is added to the polycondensation reactor 1. The structure of the film spraying component 1h is shown in FIG. Figure 3 The pipe is connected to the top center of the conical box. The conical box extends horizontally in the upper part of the inner cavity of the polycondensation reactor 1. The lower part of the conical box narrows symmetrically and forms a slit-shaped outlet at the bottom. During the material reaction stage in the polycondensation reactor 1, the material passes through the polycondensation gear pump 1c and the electric three-way valve S1, and then through the film spraying component 1h for self-circulation. The material flowing out of the slit of the film spraying component 1h is in a thin film state, which enlarges the evaporation surface of the material, is conducive to the volatilization and separation of small molecules in the material, accelerates the polycondensation reaction speed, and plays a partial role of the agitator.

[0033] The polycondensation kettle 1 is provided with a polycondensation heat medium pump 1a and a temperature control regulating valve group 1b. The heat medium pipe at the outlet of the polycondensation heat medium pump 1a supplies heat to the heating coil and heating jacket of the polycondensation kettle 1. The heat medium flowing out of the heating coil and heating jacket of the polycondensation kettle 1 returns to the inlet circulation of the polycondensation heat medium pump 1a, or returns to the inlet circulation of the polycondensation heat medium pump 1a through the heat medium radiator 3, or returns to the primary heat medium return pipe G3 for circulation; the primary heat medium supply pipe G2 is connected to the inlet pipe of the polycondensation heat medium pump 1a through the temperature control regulating valve group 1b.

[0034] Polycondensation reactor 1 is under vacuum, with a vacuum pressure of ≤60 Pa(A). The pre-condensation material is pumped into the polycondensation reactor 1 via the pre-condensation gear pump. The agitator and polycondensation gear pump 1c are activated to self-circulate the material. Directly into the vacuum environment, the polycondensation reaction is further promoted by controlling the agitator, film spraying components, temperature, and vacuum pressure. Viscosity changes can be monitored online using a viscometer 4 to achieve the required intrinsic viscosity for the product. Normal viscosity for PET is 0.640-0.680 dl / g, for PETG 0.730-0.830 dl / g, and for PBT 0.900-1.25 dl / g. When the material viscosity reaches the required product viscosity, the electric three-way valve S1 is switched on and off, using the polycondensation gear pump 1c as the power source, to deliver the material to the pelletizer for pelletizing. The entire granulation process takes approximately 30 minutes. Maintaining negative pressure within polycondensation reactor 1 during discharge effectively minimizes the viscosity drop between the head and tail of the material during discharge, achieving a viscosity drop of ≤0.004 dl / g. Conventional nitrogen-pressurized discharge achieves a viscosity drop of ≤0.008 dl / g between the head and tail, demonstrating that negative pressure discharge mitigates thermal degradation. Because the material has already undergone pre-polycondensation in the second esterification pre-polycondensation reactor 5, reaching an intrinsic viscosity of 0.330-0.400 dl / g, the residence time of the material within polycondensation reactor 1 is shortened. The total reaction time plus discharge time is approximately 2.2-2.5 hours, enabling the production of 9-10 batches of differentiated PET products per day.

[0035] Cooling water is introduced into the shell side of the No. 2 cooler 1d and the jacket of the No. 2 cyclone separator 1e.

[0036] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation methods without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A polycondensation kettle with rapid devolatilization, comprising a kettle body, an inner cavity of the kettle body provided with a heating coil and a frame-type agitator, a heating jacket provided on the outer periphery of the kettle body, and a bottom outlet of the kettle body connected to the inlet of a polycondensation gear pump, characterized in that: The outlet of the polycondensation gear pump is connected to the middle inlet of the electric three-way valve through a pipeline. The first outlet of the electric three-way valve is connected to the top center of the film spraying component through a connecting pipe. The film spraying component is located in the upper part of the inner cavity of the kettle body, extends in the horizontal direction and has a slit-shaped outlet at the bottom; the second outlet of the electric three-way valve is connected to the pelletizer granulation equipment.

2. The polycondensation kettle with rapid devolatilization according to claim 1, characterized in that: The film spraying component is a tapered box extending in the horizontal direction, with an upper portion having a square cross section and a lower portion having an isosceles triangle cross section with a narrowed bottom.

3. The rapid devolatilization polycondensation kettle according to claim 1, characterized in that: A downward-guiding spiral stirring blade is wound around the central axis of the frame-type stirrer.

4. The polycondensation kettle with rapid devolatilization according to claim 1, characterized in that: The heat medium pipeline at the outlet of the condensation heat medium pump is connected to the heat medium inlet of the heating coil and the heating jacket. The heat medium outlet of the heating coil and the heating jacket is connected to the inlet of the condensation heat medium pump through a heat medium radiator, and is connected to the primary heat medium return pipe; the primary heat medium supply pipe is connected to the inlet pipe of the condensation heat medium pump through a temperature control valve group.

5. The rapid devolatilization polycondensation reactor according to any one of claims 1 to 4, characterized in that: The gas phase outlet of the polycondensation kettle is connected to the inlet of the No. 2 cooler, and the top gas phase outlet of the No. 2 cooler is connected to the inlet of the No. 2 cyclone separator; the bottom liquid phase outlet of the No. 2 cooler and the No. 2 cyclone separator is connected to the inlet of the No. 2 polycondensation receiving tank; the top balance outlet of the No. 2 cyclone separator is connected to the top balance inlet of the No. 2 polycondensation receiving tank, and the top gas phase outlet of the No. 2 cyclone separator is connected to the inlet of the No. 2 buffer tank, and the top outlet of the No. 2 buffer tank is connected to the inlet of the polycondensation vacuum pump group.

6. The polycondensation kettle with rapid devolatilization according to claim 5, characterized in that: The polycondensation vacuum pump group includes three-stage Roots pumps connected in series, and the outlet of the last-stage Roots pump is connected to the inlet of the dry screw pump.

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