A method and reactor for melting polycondensation by falling film between horizontal tubes

Abstract

The present invention discloses a method for melt polycondensation by falling film between horizontal tubes, in which the molten material flows in a curtain-like falling film in the gap between two adjacent horizontal tubes, undergoes melt polycondensation reaction between the horizontal tubes of the next layer, and finally slides down and converges to the bottom of the reactor for further reaction and mixing and homogenization, and the reaction is completed and discharged. The polycondensation reactor implementing this method is an integral vertical structure, including a vertical tower body, a head provided with a material chamber, and a bottom shell provided with an agitator, etc. The reactor is provided with two or more falling film elements consisting of multiple horizontal tubes placed in parallel up and down and connected to vertical tubes at both ends. The falling film elements are installed vertically, and two adjacent horizontal tubes in the falling film elements and two adjacent groups of falling film elements at the same horizontal position form an associated structure. The reactor has low flow resistance, a large material film forming area, and a wide flow rate application range, and can be applied to the production of polymers prepared by melt polycondensation.

Description

Technical Field

[0001] The invention relates to a transverse tube inter-tube falling film melt polycondensation method and a reactor thereof for melt polycondensation reaction, belonging to the technical field of materials and chemical production. Background Art

[0002] Polycondensation plays an important role in the synthesis of polymer materials. Polyesters, polyamides, phenolic resins, epoxy resins, alkyd resins and other polymers are mostly synthesized by polycondensation reactions. Methods for implementing polycondensation reactions include melt polycondensation, solid phase polymerization, solution polymerization and interfacial polycondensation, among which melt polycondensation is one of the most commonly used methods. Due to the reversibility of melt polycondensation, it is necessary to use decompression or other means to remove by-products during the implementation process to move the reaction towards the polymer. Especially in the preparation of high molecular weight polycondensates, the melt viscosity is high and the removal of small molecular by-products is difficult. It is necessary to increase the surface renewal frequency and mass transfer area of ​​the material, and the key to its implementation lies in the melt polycondensation reactor. The ideal polycondensation reactor should meet the requirements of material flow close to plug flow, fast surface renewal frequency, uniform heat and mass transfer and high transfer area, narrow residence time distribution, and no dead zone in the flow. In this way, efficient devolatilization can be achieved to obtain polycondensation products of uniform quality.

[0003] Among the existing polycondensation reactors, disc-type reactors are widely used in industry due to their high internal stirring power and ability to meet large-capacity production requirements. However, long-term operation of the disc-type reactor causes disturbances in the stirring shaft, making shaft sealing increasingly difficult. The reactor wall is prone to coking due to residual materials, and the reactor cannot be used to produce high-viscosity and high-molecular-weight polymer products (such as polyester bottle flakes and polymer melts for industrial fibers). Summary of the Invention

[0004] The first objective of the present invention is to address the shortcomings of existing technologies and provide a method for melt polycondensation in a horizontal tube-to-tube falling film process. This method achieves high film-forming efficiency, uniform material flow, rapid surface renewal, high devolatilization efficiency, and significant viscosity-enhancing effects, ultimately enabling the production of high-quality polymers. To this end, the present invention employs the following technical solutions:

[0005] A method for melting and polycondensing falling films between horizontal tubes is characterized in that: the method is equipped with two or more falling film elements consisting of multiple horizontal tubes placed in parallel vertically and connected to vertical tubes at both ends. The horizontal tubes at the same horizontal position in two adjacent groups of falling film elements and the two horizontal tubes adjacent to each other in the same group of falling film elements are also related. The molten material falls in the form of a curtain in the gap between the horizontal tubes at the same horizontal position in the two adjacent groups of falling film elements and flows to the horizontal tubes corresponding to the two adjacent groups of falling film elements directly below, and finally slides down and converges to the bottom of the reactor for further reaction and mixing and homogenization, and the material is discharged after the reaction is completed.

[0006] Another object of the present invention is to provide a falling film melt polycondensation reactor using the above method. To this end, the present invention adopts the following technical solutions:

[0007] A transverse tube intertube falling film melt polycondensation reactor comprises a vertical tower body, a head, and a bottom shell. The vertical tower body is provided with a vacuum exhaust port; the reactor is provided with a material inlet, and the bottom shell is provided with a material outlet; a material chamber is provided at the upper portion of the reactor, and is characterized in that: the reactor is provided with two or more groups of falling film elements each consisting of a plurality of transverse tubes arranged in parallel vertically and connected to vertical tubes at both ends; the falling film elements are installed vertically, two adjacent transverse tubes in the falling film elements are associated, and two adjacent groups of falling film elements are also associated; the bottom plate of the material chamber is a film distribution plate, and the film distribution plate has film distribution holes provided for the transverse tubes;

[0008] The molten material is distributed from the film distribution plate and enters between the two horizontal tubes at the same horizontal position of two adjacent groups of falling film elements. The two adjacent groups of falling film elements are related, and the two adjacent horizontal tubes on the same group of falling film elements are also related. The material is gathered between the two horizontal tubes at the same horizontal position of the two adjacent groups and flows from the gap between the tubes in the form of a curtain falling film to the gap between the two corresponding horizontal tubes below. The melt undergoes melt polycondensation reaction while flowing in the gap between the two tubes and falling film movement between the upper and lower horizontal tubes.

[0009] Furthermore, the membrane plate is provided with a plurality of membrane holes for each two adjacent transverse tubes thereunder, and the projections of the membrane holes along the tower body direction are located between the central axes of the two transverse tubes.

[0010] Furthermore, in the transverse tube layer, that is, the transverse tubes at the same height, the ratio of the tube spacing between two transverse tubes of adjacent falling film elements (the distance between the adjacent side tops of two adjacent transverse tubes) to the circumscribed circle diameter of the transverse tube is 0.1 to 10, and the ratio of the layer spacing between upper and lower adjacent transverse tube layers (the distance between the upper and lower ends of the outer walls of upper and lower adjacent transverse tubes) to the tube outer diameter is 1 to 500.

[0011] Furthermore, from top to bottom, the tube spacing of the horizontal tubes on the same layer is the same or gradually increases, and the ratio of the tube spacing of the top horizontal tubes to the tube spacing of the bottom horizontal tubes is 1:1 to 5; and / or, from top to bottom, the interlayer spacing between layers is the same or gradually increases, and the ratio of the interlayer spacing at the top to the interlayer spacing at the bottom is 1:1 to 20.

[0012] Furthermore, the upper portion of the transverse tube is in the shape of a raised arc or triangle, and the cross section of the transverse tube can be circular, elliptical, egg-shaped, or polygonal.

[0013] Furthermore, the transverse tube may be a corrugated tube.

[0014] Furthermore, the diameter of the transverse tube in the falling film element remains constant or gradually decreases from top to bottom.

[0015] Furthermore, the reactor is provided with an insulation and heat transfer system, an upper heat medium chamber and a lower heat medium chamber, a heat medium inlet and a heat medium outlet are provided in the head, and the material chamber is located below the lower heat medium chamber; the vertical tower body and the bottom shell are respectively provided with a tower body jacket and a bottom shell jacket; the upper top plate of the material chamber is the bottom plate of the lower heat medium chamber, the vertical tube on one side of the falling film element passes through the material chamber and the lower heat medium chamber and is communicated with the upper heat medium chamber, the vertical tube on the other side of the falling film element passes through the material chamber and is communicated with the lower heat medium chamber, and after entering the upper heat medium chamber, the heat medium flows through the vertical tube on one side of the falling film element and is diverted into the horizontal tube layer, and then passes through the vertical tube on the other side, and then flows to the lower heat medium chamber, and flows out from the heat medium outlet on the head; the heat medium of the heat transfer and insulation system circulates to the outside and circulates after being heated or cooled.

[0016] By regulating the material flow rate, the structural parameters, and the spacing between two adjacent sets of horizontal tubes, the material enters between two sets of horizontal tubes at the same height, flows out through the gap between the two sets of horizontal tubes by gravity, and then converges between two adjacent horizontal tubes in the next layer. This ingeniously designed inter-tube falling film structure effectively promotes uniform melt mixing, utilizing its own weight to pull the film, thereby improving film formation efficiency and mass transfer area. This accelerates the removal of small molecular compounds in the melt polycondensation system, resulting in high-quality, highly viscous melt polycondensation products. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the transverse tube intertube falling film melt polycondensation reactor of the present invention.

[0018] Figure 2 This is the falling film flow diagram of the material between two adjacent groups of horizontal tubes.

[0019] Figure 3 Schematic diagram of the relative position arrangement of the membrane holes relative to the two groups of cross tubes.

[0020] Components, parts and numbers in the figure: heat medium inlet 1, feed pipe 2, heat medium inlet box 3, heat medium outflow box 4, heat medium box outflow box upper cover 41, heat medium box outflow box lower bottom plate 42, material chamber 5, membrane plate 51, membrane hole 511, tower jacket heat medium inlet 6, vertical shell 7, tower jacket 8, bottom shell flange 9, bottom shell bolts 10, bottom shell jacket heat medium inlet 11, bottom shell 12, bottom shell jacket 13, material outlet 14, bottom shell jacket heat medium outlet 15, agitator 16, cofferdam 17, cofferdam outlet 18, tower jacket heat medium outlet 19, falling film element 20, horizontal cross tube 201 in falling film element, vertical tube 202 in falling film element, vacuum exhaust port 21, shell flange 22, shell bolts 23, heat medium outlet 24, head 25, material inlet 26. DETAILED DESCRIPTION

[0021] As shown in the figure, a transverse tube inter-tube falling film melt condensation reactor provided in this embodiment includes a vertical tower body 7, a head 25 and a bottom shell 12. A vacuum exhaust port 21 is provided on the vertical tower body 7; the reactor is provided with a material inlet 26 on the head 25 and a material outlet 14 on the bottom shell 12; a material chamber 5 is provided on the upper part of the reactor.

[0022] The reactor is provided with two or more groups of falling film elements 20 consisting of multiple horizontal tubes 201 arranged in parallel vertically and connected to vertical tubes 202 at both ends. The falling film elements 20 are installed vertically, and the horizontal tubes 201 of the same height of each group of falling film elements are in the same horizontal tube layer.

[0023] The two adjacent horizontal tubes in the falling film element are associated, and the horizontal tubes at the same height of two adjacent groups of falling film elements are also associated. The bottom plate 51 of the material chamber 5 is a membrane plate, and the membrane plate has membrane holes 511 set for the horizontal tubes. The membrane plate is provided with multiple membrane holes 511 for each two adjacent horizontal tubes 2101 below it. The axial projection of the membrane hole 511 along the tower body direction is located between the central axes of the two adjacent horizontal tubes 291.

[0024] After being distributed from the film distribution plate 51, the molten material enters between the two horizontal tubes 201 at the same horizontal position of two adjacent groups of falling film elements. The material is guided by the arc surface or inclined surface of the two tubes between the two horizontal tubes 201 at the same horizontal position of the two adjacent groups and gradually gathers and falls from the gap between the tubes into the gap between the two corresponding horizontal tubes below. The melt undergoes a melt polycondensation reaction while flowing in the gap between the two tubes and falling film movement between the upper and lower horizontal tubes.

[0025] The ratio of the tube spacing (the distance between the top ends of adjacent sides of two adjacent transverse tubes) between two adjacent transverse tubes 221 in a transverse tube layer to the circumscribed diameter of the transverse tubes is 0.1 to 10, and the ratio of the interlayer spacing (the distance between the upper and lower ends of the outer walls of upper and lower adjacent transverse tubes) between upper and lower adjacent transverse tube layers to the tube outer diameter is 1 to 500. As a preferred embodiment, the diameter of the transverse tubes 221 in the falling film element gradually decreases from top to bottom.

[0026] From top to bottom, the spacing between horizontal tubes on the same layer is the same or gradually increases, and the ratio of the spacing between horizontal tubes on the top layer to the spacing between horizontal tubes on the bottom layer is 1:1 to 5; and / or, from top to bottom, the interlayer spacing between layers is the same or gradually increases, and the ratio of the interlayer spacing at the top to the interlayer spacing at the bottom is 1:1 to 20.

[0027] In addition to being circular, the cross-sectional shape of the transverse tube can have many options, including an elliptical shape, an egg shape, an arc shape or a triangle shape with a convex upper portion, or other polygonal shapes, as long as the two adjacent transverse tubes 221 have an arc surface or an inclined surface above the narrowest gap between the tubes to form an inlet groove.

[0028] Preferably, the transverse tube can be a corrugated tube.

[0029] A groove-shaped cofferdam 17 is provided at the bottom of the vertical tower body, and a cofferdam outlet 18 is provided on the cofferdam, which is connected to the outside of the kettle and can be used to discharge residues on the inner wall of the tower body.

[0030] The reactor is equipped with a heat preservation and heat transfer system. The head is provided with an upper heat medium chamber (heat medium flows into the box 3) and a lower heat medium chamber (heat medium flows out of the box 4), a heat medium inlet 1 and a heat medium outlet 24. The vertical tower body 7 and the bottom shell 12 are respectively provided with a tower jacket 8 and a bottom shell jacket 13. The tower jacket 8 is provided with a tower jacket heat medium inlet 6 and a tower jacket heat medium outlet 19. The bottom shell jacket 13 is provided with a bottom shell jacket heat medium inlet 11 and a bottom shell jacket heat medium outlet 15. The upper top plate of the material chamber 5 is the bottom plate of the lower heat medium chamber (the lower bottom plate 42 of the heat medium box outflow box). One end of the feed pipe 2 is connected to the material inlet 26, and the other end passes through the upper heat medium chamber and the lower heat medium chamber and reaches the material chamber 5. The vertical pipe 202 on one side of the falling film element 20 passes through the material chamber 5 and the lower heat medium chamber and communicates with the upper heat medium chamber. The vertical pipe 202 on the other side of the falling film element passes through the material chamber 5 and communicates with the lower heat medium chamber. After entering the upper heat medium chamber, the heat medium flows through the vertical pipe on one side of the falling film element and enters the horizontal pipe layer, then flows out to the lower heat medium chamber and flows out from the heat medium outlet 24 on the head; the heat medium of the heat transfer and insulation system circulates to the outside and is heated or cooled before circulating.

[0031] The melt polycondensation method using the above-mentioned transverse tube intertube falling film reactor is as follows:

[0032] The heat medium flows in through the heat medium inlet on the head 3, flows from the upper heat medium chamber into the vertical tube on one side of the falling film element, and then is divided into the horizontal tube connected to it, and then flows out from the vertical tube on the other side of the falling film element to the lower heat medium chamber, and finally flows from the lower heat medium chamber to the external circulation of the polycondensation reactor.

[0033] The horizontal tube inter-tube falling film reactor is equipped with two or more groups of falling film elements consisting of multiple horizontal tubes placed parallel to each other and connected to vertical tubes at both ends. The horizontal tubes at the same horizontal position in two adjacent groups of falling film elements and the two adjacent horizontal tubes in the same group of falling film elements are also related. The molten material falls by gravity in the gap between the two horizontal tubes at the same horizontal position in the two adjacent groups of falling film elements, and flows in the form of a curtain-like falling film to the two horizontal tubes corresponding to the two adjacent groups of falling film elements directly below, and finally slides and converges to the bottom of the reactor for further reaction and is mixed and homogenized by the agitator 16 arranged at the bottom. The material is discharged after the reaction is completed.

[0034] The above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. Ordinary technicians in the relevant technical field may make various changes and modifications without departing from the scope of the present invention. Therefore, all equivalent technical solutions should also fall within the scope of the present invention. The scope of patent protection of the present invention should be defined by the claims.

Claims

1. A falling film melt polycondensation method between horizontal tubes, characterized by: The method is equipped with two or more groups of falling film elements consisting of multiple horizontal tubes arranged in parallel vertically and connected to vertical tubes at both ends. The horizontal tubes at the same horizontal position in two adjacent groups of falling film elements and the two horizontal tubes adjacent to each other in the same group of falling film elements are also related. The molten material falls in the form of a curtain in the gap between the horizontal tubes at the same horizontal position in the two adjacent groups of falling film elements and flows to the horizontal tubes corresponding to the two adjacent groups of falling film elements directly below, and finally slides down and converges to the bottom of the reactor for further reaction and mixing and homogenization, and the material is discharged after the reaction is completed.

2. A horizontal tube intertube falling film melt polycondensation reactor comprising a vertical tower body, a head, and a bottom shell, wherein the vertical tower body is provided with a vacuum pumping port; the reactor is provided with a material inlet, and the bottom shell is provided with a material outlet; a material chamber is provided in the upper portion of the reactor, characterized in that: The reactor is provided with two or more groups of falling film elements consisting of multiple horizontal tubes placed in parallel vertically and connected to vertical tubes at both ends. The falling film elements are installed vertically, and the two adjacent horizontal tubes in the falling film elements are associated with each other. The two adjacent groups of falling film elements are also associated. The bottom plate of the material chamber is a film plate with film holes set for the horizontal tubes. The molten material is distributed from the film distribution plate and enters between the two horizontal tubes at the same horizontal position of two adjacent groups of falling film elements. The two adjacent groups of falling film elements are related, and the two adjacent horizontal tubes on the same group of falling film elements are also related. The material is gathered between the two horizontal tubes at the same horizontal position of the two adjacent groups and flows from the gap between the tubes in the form of a curtain falling film to the gap between the two corresponding horizontal tubes below. The melt undergoes melt polycondensation reaction while flowing in the gap between the two tubes and falling film movement between the upper and lower horizontal tubes.

3. A horizontal tube intertube falling film melt polycondensation reactor according to claim 2, characterized in that: The membrane plate is provided with a plurality of membrane holes for each two adjacent horizontal tubes below it, and the projections of the membrane holes along the vertical direction of the tower body are located between the central axes of the two horizontal tubes.

4. A horizontal tube inter-tube falling film melt polycondensation reactor according to claim 2, characterized in that: The ratio of the tube spacing between two horizontal tubes at the same horizontal position of two adjacent groups of falling film elements to the circumscribed circle diameter of the horizontal tube is 0.1-10, and the ratio of the layer spacing between upper and lower adjacent horizontal tubes to the tube diameter is 1-500.

5. The horizontal tube inter-tube falling film melt polycondensation reactor according to claim 2, characterized in that: From top to bottom, the spacing between horizontal tubes on the same layer is the same or gradually increases, and the ratio of the spacing between horizontal tubes on the top layer to the spacing between horizontal tubes on the bottom layer is 1:1 to 5; and / or, from top to bottom, the interlayer spacing between layers is the same or gradually increases, and the ratio of the interlayer spacing at the top to the interlayer spacing at the bottom is 1:1 to 20.

6. A horizontal tube inter-tube falling film melt polycondensation reactor according to claim 2, characterized in that: The upper part of the transverse tube is a convex arc or triangle, and the cross section of the transverse tube is circular, elliptical, egg-shaped or polygonal.

7. A horizontal tube inter-tube falling film melt polycondensation reactor according to claim 2, characterized in that: The diameter of the transverse tube in the falling film element remains constant or gradually decreases from top to bottom.

8. The horizontal tube inter-tube falling film melt polycondensation reactor according to claim 2, characterized in that: The reactor is equipped with an insulation and heat transfer system, and an upper heat medium chamber and a lower heat medium chamber, a heat medium inlet and a heat medium outlet are arranged in the head, and the material chamber is located below the lower heat medium chamber; the vertical tower body and the bottom shell are respectively provided with a tower body jacket and a bottom shell jacket; the upper top plate of the material chamber is the bottom plate of the lower heat medium chamber, and the vertical pipe on one side of the falling film element passes through the material chamber and the lower heat medium chamber to communicate with the upper heat medium chamber, and the vertical pipe on the other side of the falling film element passes through the material chamber to communicate with the lower heat medium chamber. After entering the upper heat medium chamber, the heat medium flows through the vertical pipe on one side of the falling film element to be diverted into the horizontal pipe layer, and then through the vertical pipe on the other side, and then flows to the lower heat medium chamber, and flows out from the heat medium outlet on the head; the heat medium of the heat transfer and insulation system circulates to the outside and circulates after being heated or cooled.

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