Double-tower column reactor for polyester resin production

Abstract

The utility model discloses a polyester resin production is with double tower column reation kettle relates to polyester resin production technical field, including reation kettle main part, esterification tower column and polycondensation tower column, and esterification tower column, polycondensation tower column chooses one and communicates with reation kettle main part, and the tower resistance of polycondensation tower column is less than the tower resistance of esterification tower column, esterification tower column bottom end communicates with reation kettle main part, and esterification tower column middle part position is provided with packing assembly and fractionating condenser from bottom to top in proper order, and the control valve on esterification tower column communicates with esterification tower column top end to make esterification tower column inner chamber constitute from bottom to top and flow to the working channel. The utility model discloses through double tower column type design, and make the tower resistance of polycondensation tower column less than the tower resistance of esterification tower column, and two tower columns choose one and communicate with reation kettle main part, make esterification reaction and polycondensation reaction carry out in the corresponding tower column respectively, make two reactions independent of each other, do not interfere with each other, fundamentally solve the technical contradiction of traditional single tower column.

Description

Technical Field

[0001] This utility model relates to the field of polyester resin production technology, specifically to a double-column reactor for polyester resin production. Background Technology

[0002] Polyester resins are high molecular weight compounds synthesized from diols (or polyols) and diacids (or polyacids) through a polycondensation reaction. Based on their molecular structure, they are mainly divided into two categories: saturated polyester resins and unsaturated polyester resins. In industrial production, esterification dehydration and vacuum polycondensation are two core steps that determine product performance: the former removes water molecules generated in the reaction, pushing the chemical equilibrium towards the forward reaction direction; the latter removes small molecule byproducts under high-temperature and high-vacuum conditions, thereby effectively increasing the molecular weight and degree of polymerization of the resin.

[0003] Based on initial process design considerations, since esterification dehydration and vacuum polycondensation have certain similarities in their process appearance (for example, both require the separation of small molecules from high-viscosity melts under heating conditions), and in order to simplify equipment layout and reduce initial investment costs, current technical routes tend to adopt a single-column structure to achieve the above two functions.

[0004] However, with the accumulation of practical experience in production, technicians gradually realized that single-column structures have at least the following two serious defects: First, there is an inherent conflict in process efficiency. The esterification and dehydration stage relies on a large amount of packing material in the tower to form suitable tower resistance, so as to ensure sufficient gas-liquid contact and efficient separation; however, after entering the vacuum polycondensation stage, these packing materials become the main obstacle to establishing a high vacuum environment. The flow resistance they generate greatly delays the establishment and stabilization of high vacuum, directly leading to a longer polycondensation reaction cycle and severely restricting the overall production efficiency.

[0005] Secondly, there is a risk of cross-contamination of product quality. During the vacuum polycondensation stage, unreacted monomers, oligomers, and other small molecules are easily trapped in the complex pores of the filler layer. When the system switches to the next batch of esterification reaction, these residues will re-enter the reaction system with the reflux material, causing contamination of the raw material composition between different batches. This will ultimately lead to fluctuations in the molecular weight distribution and functionality of the product, affecting the consistency and stability of product quality. Utility Model Content

[0006] The purpose of this invention is to solve the problems in the prior art by proposing a double-column reactor for polyester resin production. Through the double-column design, the esterification reaction and the polycondensation reaction are carried out separately, so that the two reactions are independent and do not interfere with each other. This not only avoids process efficiency conflicts, but also reduces the risk of cross-contamination.

[0007] To solve the above problems, this utility model provides the following technical solution: A dual-column reactor for polyester resin production includes a reactor body, an esterification column, and a polycondensation column, wherein either the esterification column or the polycondensation column is connected to the reactor body, and the resistance of the polycondensation column is less than that of the esterification column. The bottom end of the esterification column is connected to the main body of the reactor. The packing assembly and the condenser are arranged sequentially from bottom to top in the middle of the esterification column. The control valve on the esterification column is connected to the top of the esterification column so that the inner cavity of the esterification column forms a working channel from bottom to top. The polycondensation column is equipped with a vacuum valve that communicates with its inner cavity to create a vacuum environment inside the polycondensation column.

[0008] As a further embodiment of this utility model: the top of the esterification column is provided with a first pipe communicating with its inner cavity, and a control valve is provided on the first pipe.

[0009] As a further embodiment of this utility model: the bottom end of the polycondensation column is connected to the main body of the reactor through a second pipe, and a vacuum valve is set at the top of the polycondensation column.

[0010] As a further embodiment of this utility model: a third pipe is provided at the top of the polycondensation tower column and communicates with its inner cavity, and a vacuum valve is provided on the third pipe.

[0011] As a further embodiment of this utility model, the inner cavity of the polycondensation tower column is provided with a packing carrier.

[0012] As a further embodiment of this utility model: both the bottom end of the esterification column and the second pipeline are equipped with opening and closing valves, and one of the two opening and closing valves is selected to be in the open state, so as to achieve selective connection between the esterification column, the polycondensation column and the reactor body.

[0013] As a further aspect of this invention, the reactor also includes a cleaning assembly for cleaning the inner cavity of the polycondensation column.

[0014] As a further embodiment of this utility model: the cleaning assembly includes a liquid storage tank, a first cleaning pipe and a second cleaning pipe. One end of the first cleaning pipe and the second cleaning pipe are both connected to the liquid storage tank. The other end of the first cleaning pipe is connected to the bottom end of the polycondensation tower column. The other end of the second cleaning pipe extends into the polycondensation tower column and is provided with several spray nozzles. A drive source is connected to the second cleaning pipe.

[0015] As a further embodiment of this utility model: a filter is connected to the first cleaning pipe, and a shut-off valve is provided on the first cleaning pipe.

[0016] As a further embodiment of this utility model: a scraper ring is slidably installed in the inner cavity of the polycondensation tower column along its length direction, and the outer edge of the scraper ring is in contact with the inner cavity wall of the polycondensation tower column. A threaded rod is rotatably provided in the inner cavity of the polycondensation tower column along its length direction, and the scraper ring is threadedly sleeved on the outside of the threaded rod, so that the scraper ring can slide along the length direction of the inner cavity of the polycondensation tower column when the threaded rod rotates.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. By employing a dual-column design, and ensuring that the resistance of the polycondensation column is less than that of the esterification column, with one column connected to the main reactor body, the esterification and polycondensation reactions proceed independently within their respective columns. This fundamentally resolves the technical limitations of traditional single-column systems. Specifically: The esterification column is specially equipped with packing components and a condenser, providing a distillation separation environment for the esterification dehydration reaction, ensuring that water is removed efficiently and the feed is effectively reused.

[0018] Polycondensation columns are specifically designed for connection to high vacuum systems. Their interiors are spacious or free of dense packing, enabling the rapid establishment and stable maintenance of a high vacuum environment, thereby greatly improving the efficiency and molecular weight of the polycondensation reaction.

[0019] 2. The inner wall of the condensation tower column is sprayed and washed through the second cleaning pipe equipped with a spray head. At the same time, the cleaning liquid can be recycled and filtered through the first cleaning pipe for reuse. This saves cleaning agent, realizes automated cleaning, and greatly reduces the downtime of traditional manual cleaning.

[0020] 3. The addition of a filter can effectively remove impurities from the cleaning solution, prevent nozzle clogging, and ensure cleaning results.

[0021] 4. The scraping ring is driven by a threaded rod to move up and down inside the tower wall, which can actively scrape off polymer residues or gels adhering to the inner wall of the tower. Combining this scraping action with spray cleaning further improves the cleaning effect and cleaning efficiency.

[0022] 5. By setting a packing carrier inside the polycondensation tower column, the packing carrier has very little tower resistance to the vacuum polycondensation reaction and does not interfere with the vacuum polycondensation reaction. It can also act as a carrier to keep most of the substances brought out during vacuuming on the packing carrier, thus protecting the vacuum system connected to the vacuum valve. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings.

[0024] Figure 1 This is a cross-sectional view of the present invention. Figure 1 ; Figure 2This is a three-dimensional structural diagram of the scraper ring and threaded rod in this utility model; Figure 3 This is a cross-sectional view of the present invention. Figure 2 .

[0025] In the diagram: 1. Reactor body; 2. Esterification column; 3. Polycondensation column; 4. Packing assembly; 5. Condenser; 6. Control valve; 7. Vacuum valve; 8. First pipeline; 9. Second pipeline; 10. Third pipeline; 11. On / off valve; 12. Storage tank; 13. First cleaning pipeline; 14. Second cleaning pipeline; 15. Spray head; 16. Drive source; 17. Filter; 18. Shut-off valve; 19. Scraper ring; 20. Threaded rod; 21. Guide rod; 22. Packing carrier. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0027] Example 1: like Figure 1 As shown, a dual-column reactor for polyester resin production includes a reactor body 1 with a set of columns mounted thereon. The bottom end of each column is connected to the reactor body 1, and an on / off valve 11 is provided at the bottom end of the column. The on / off valve 11 is used to open or close the connection between the bottom end of the column and the reactor body 1. Esterification reactions can be carried out using this column, which is referred to as the esterification column 2. From a simplified design perspective, the reactor body 1 can be directly selected as a single-column reactor with esterification and polycondensation functions in the prior art. However, in subsequent operations, only the esterification function of the single-column reactor will be used.

[0028] Furthermore, this application also includes a column, the bottom end of which is connected to the reactor body 1 via a second pipe 9, and the second pipe 9 is also equipped with an on / off valve 11, which is used to open or close the connection between the bottom end of the column and the reactor body 1; the column can be used to carry out a polycondensation reaction, and the column is referred to as a polycondensation column 3.

[0029] In summary, the reactor body 1 of this application, relying on the esterification column 2 and the polycondensation column 3 connected to it, allows for the separate conduction of esterification and polycondensation reactions by selectively opening one of the two sets of on / off valves 11. This ensures that the two reactions are independent and do not interfere with each other, and the resistance of the polycondensation column 3 is less than that of the esterification column 2. The structures of the two columns are described below: (1) Esterification column 2: The middle part of the esterification column 2 is provided with packing components (such as Pall rings or step rings) 4 and condenser 5 from bottom to top. The control valve 6 on the esterification column 2 is connected to the top of the esterification column 2 so that the inner cavity of the esterification column 2 forms a working channel from bottom to top.

[0030] The workflow is as follows: First, the raw materials (diols / polyols and diacids / polyacids, etc.) are heated to a molten state in the reactor body 1 and initially mixed. Then, the reactor body 1 is heated to the esterification reaction temperature (usually 200-250 degrees Celsius), and the esterification reaction begins, generating polyester chains and water vapor. Next, the water vapor generated by the reaction, together with excess, vaporized diol vapor, forms mixed steam, which rises from the reactor body 1 and enters the bottom of the esterification column 2. At this time, the valve 11 on the second pipe 9 is closed, and the valve 11 at the bottom of the esterification column 2 is open, allowing the mixed steam to enter the esterification column 2 and flow from bottom to top, passing through the packing assembly 4. The partial condenser 5 located above the packing assembly 4 begins to work, and by precisely controlling the temperature, the diol vapor with a higher boiling point is condensed into liquid. The condensed diol droplets flow downward along the surface of the packing assembly 4 under the action of gravity and return to the reactor body 1. Meanwhile, the water vapor with a lower boiling point cannot be condensed and continues to rise in gas form. At this time, the control valve 6 located at the top of the esterification column 2 is open, and the uncondensed water vapor (and a small amount of light components) is discharged from the top of the esterification column 2.

[0031] During this process, water is continuously removed from the reaction system, and according to Le Chatelier's principle, the chemical reaction continues in the direction of ester formation.

[0032] (2) Polycondensation column 3: A vacuum valve 7 is provided on the polycondensation column 3 and is connected to its inner cavity. The vacuum valve 7 has the function of drawing a vacuum in the inner cavity of the polycondensation column 3 to create a vacuum environment in the inner cavity of the polycondensation column 3, which facilitates the subsequent vacuum polycondensation reaction.

[0033] The workflow is as follows: After the esterification reaction reaches its endpoint (acid value is qualified, water discharge basically stops), the process switches from esterification mode to polycondensation mode: the on / off valve 11 at the bottom of the esterification column 2 is closed, and the on / off valve 11 on the second pipe 9 is opened. During this process, the reactor body 1 continues to be heated to maintain the high-temperature molten state of the material. Then, the vacuum valve 7 at the top of the polycondensation column 3 (which is connected to a vacuum pump in the prior art) is opened. As explained above, the vacuum valve 7 has a vacuuming function, and the gas is evacuated from the inner cavity of the polycondensation column 3. Under the combined action of high vacuum and high temperature, the trace amounts of water, residual free monomers (such as ethylene glycol), and small molecule byproducts (such as ethylene glycol) that are most difficult to remove from the melt in the reactor body 1 gain sufficient volatilization power and escape from the high-viscosity polymer melt. These escaped small molecules form a gas flow that rises from the reactor body 1 and enters the polycondensation column 3 through the second pipe 9.

[0034] During this process, as small molecule byproducts are continuously removed, the reaction equilibrium is disrupted, driving the continuous growth of polymer molecular chains.

[0035] It should be noted that the composition of the esterification column 2 and the polycondensation column 3 described above, even without a detailed description of all their components, does not affect their possession of all the components and functions required for esterification and polycondensation reactions in a single column in the prior art. Taking the heating function as an example, the inner wall of the corresponding column is wound with a nickel-chromium alloy heating wire, which, together with a temperature sensor, can heat the column wall temperature to 120-150℃, thus realizing the heating function of the column.

[0036] To facilitate the installation of control valve 6, a first pipe 8 communicating with its inner cavity can be provided at the top of the esterification column 2, and control valve 6 can be installed on the first pipe 8. To facilitate the installation of vacuum valve 7, a third pipe 10 communicating with its inner cavity can be provided at the top of the polycondensation column 3, and vacuum valve 7 can be installed on the third pipe 10.

[0037] Example 2: This embodiment adds a cleaning component to the first embodiment. The cleaning component is used to clean the inner cavity of the polycondensation column 3. Specifically: For example Figure 1As shown, the cleaning assembly includes a storage tank 12 containing water or cleaning fluid, a first cleaning pipe 13, and a second cleaning pipe 14. One end of the first cleaning pipe 13 and the second cleaning pipe 14 are connected to the storage tank 12. The other end of the first cleaning pipe 13 is connected to the bottom of the polycondensation column 3. The other end of the second cleaning pipe 14 extends into the polycondensation column 3 and is provided with several spray nozzles 15. A drive source 16 is connected to the second cleaning pipe 14. A filter 17 and a shut-off valve 18 are connected to the first cleaning pipe 13. A shut-off valve (not shown in the figure) 18 is also connected to the second cleaning pipe 14.

[0038] It should be noted that, based on the addition of a cleaning component in this embodiment, the shut-off valve 18 on the first cleaning pipe 13 is in a closed state during the polycondensation reaction.

[0039] After the polycondensation reaction is completed, some free monomers (such as ethylene glycol) and small molecule byproducts generated by polycondensation (such as ethylene glycol) will adhere to the inner wall of the polycondensation column 3. At this time, the on / off valve 11 on the second pipeline 9 is closed, the shut-off valve 18 on the first cleaning pipeline 13 is opened, and the drive source (such as the pump body) 16 is started. The water or cleaning liquid in the storage tank 12 will be transported to the spray head 15. The spray head 15 sprays the inner wall of the polycondensation column 3 to achieve cleaning. The cleaned waste liquid will flow from the bottom of the polycondensation column 3 into the first cleaning pipeline 13, and after being filtered by the filter 17, it will flow back into the storage tank 12.

[0040] To improve the cleaning effect, on the one hand, the spray head 15 can be selected as a rotary nozzle of the prior art to achieve all-round spraying treatment of the inner wall of the polycondensation tower column 3; on the other hand, a scraper ring 19 can be slidably installed in the inner cavity of the polycondensation tower column 3 along its length, and the outer edge of the scraper ring 19 is in contact with the inner wall of the polycondensation tower column 3. A threaded rod 20 is rotatably arranged in the inner cavity of the polycondensation tower column 3 along its length, and the scraper ring 19 is threadedly sleeved on the outside of the threaded rod 20. When the threaded rod 20 is driven to rotate, the scraper ring 19 can be driven to slide along the length of the inner cavity of the polycondensation tower column 3. At this time, the outer edge of the scraper ring 19, which is in contact with the inner wall of the polycondensation tower column 3, can perform scraping treatment. Combined with the spraying of the spray head 15, the cleaning effect is maximized.

[0041] like Figure 2 As shown in the figure, this figure illustrates the assembly relationship between the scraper ring 19 and the threaded rod 20. In this embodiment, the threaded rod 20 is selected as two sets and arranged in opposite directions. The two sets of threaded rods 20 are connected by transmission and can be driven by the same drive motor, or driven synchronously by two sets of drive motors. This synchronous drive is a conventional technical means in the prior art, and will not be described in detail here in order to avoid cumbersome writing.

[0042] For example, the sliding installation of the scraper ring 19 inside the polycondensation column 3, and so on. Figure 2 As shown, several guide rods 21 can be pre-fixed along the length of the inner cavity of the polycondensation column 3. Then, a corresponding number of through holes are opened at corresponding positions on the scraper ring 19. The scraper ring 19 is movably sleeved on the guide rods 21 through the through holes, thereby achieving the sliding installation of the scraper ring 19 in the inner cavity of the polycondensation column 3. Of course, the sliding installation of the scraper ring 19 in the inner cavity of the polycondensation column 3 is not limited to the above-mentioned setting of guide rods 21. Other conventional methods in the prior art can also be used. For example, a sliding groove can be opened along the length of the inner wall of the polycondensation column 3, and a slider can be set on the scraper ring 19 simultaneously. The sliding cooperation between the slider and the sliding groove can also achieve the sliding installation of the scraper ring 19 in the inner cavity of the polycondensation column 3.

[0043] Example 3: like Figure 3 As shown, the difference between this embodiment and Embodiment 2 is that this embodiment uses the cleaning component from the previous embodiment, but replaces the scraper ring 19 with a packing carrier 22. Specifically, the packing carrier 22 is disposed inside the polycondensation column 3. The packing carrier 22 has a very small obstructive effect, and its resistance to the vacuum polycondensation reaction is negligible. After the polycondensation reaction is completed, some free monomers (such as ethylene glycol) and small molecule byproducts generated by polycondensation (such as ethylene glycol) will adhere to and remain on the packing carrier 22. Subsequent top-down spraying treatment with the spray head 15 can wash off the deposits on the packing carrier 22.

[0044] The above description provides a detailed account of one embodiment of the present invention. However, this description is merely a preferred embodiment and should not be construed as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the claims of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A double-column reactor for polyester resin production, characterized in that, It includes a reactor body (1), an esterification column (2) and a polycondensation column (3), and one of the esterification column (2) and the polycondensation column (3) is connected to the reactor body (1), and the column resistance of the polycondensation column (3) is less than that of the esterification column (2). The bottom end of the esterification column (2) is connected to the reactor body (1). The middle part of the esterification column (2) is provided with a packing assembly (4) and a condenser (5) from bottom to top. The control valve (6) on the esterification column (2) is connected to the top of the esterification column (2) so that the inner cavity of the esterification column (2) forms a working channel from bottom to top. The condensation column (3) is equipped with a vacuum valve (7) that communicates with its inner cavity to create a vacuum environment in the inner cavity of the condensation column (3).

2. The double-column reactor for polyester resin production according to claim 1, characterized in that, The top of the esterification column (2) is provided with a first pipe (8) that communicates with its inner cavity, and a control valve (6) is provided on the first pipe (8).

3. The double-column reactor for polyester resin production according to claim 1, characterized in that, The bottom end of the polycondensation column (3) is connected to the reactor body (1) through the second pipe (9), and the vacuum valve (7) is set at the top of the polycondensation column (3).

4. The double-column reactor for polyester resin production according to claim 1, characterized in that, The top of the polycondensation column (3) is provided with a third pipe (10) that communicates with its inner cavity, and a vacuum valve (7) is provided on the third pipe (10).

5. The double-column reactor for polyester resin production according to claim 1, characterized in that, The inner cavity of the polycondensation column (3) is provided with a packing carrier (22).

6. The double-column reactor for polyester resin production according to claim 3, characterized in that, Both the bottom end of the esterification column (2) and the second pipeline (9) are equipped with opening and closing valves (11), and one of the two opening and closing valves (11) is in the open state to achieve selective connection between the esterification column (2), the polycondensation column (3) and the reactor body (1).

7. A double-column reactor for polyester resin production according to any one of claims 1-6, characterized in that, The reactor also includes a cleaning assembly for cleaning the interior of the polycondensation column (3).

8. The double-column reactor for polyester resin production according to claim 7, characterized in that, The cleaning assembly includes a liquid storage tank (12), a first cleaning pipe (13) and a second cleaning pipe (14). One end of the first cleaning pipe (13) and the second cleaning pipe (14) are connected to the liquid storage tank (12). The other end of the first cleaning pipe (13) is connected to the bottom end of the polycondensation column (3). The other end of the second cleaning pipe (14) extends into the polycondensation column (3) and is provided with several spray nozzles (15). A drive source (16) is connected to the second cleaning pipe (14).

9. A double-column reactor for polyester resin production according to claim 8, characterized in that, A filter (17) is connected to the first cleaning pipe (13), and a shut-off valve (18) is provided on the first cleaning pipe (13).

10. A double-column reactor for polyester resin production according to claim 8, characterized in that, A scraper ring (19) is slidably installed in the inner cavity of the polycondensation column (3) along its length direction, and the outer edge of the scraper ring (19) is in contact with the inner wall of the polycondensation column (3). A threaded rod (20) is rotatably provided in the inner cavity of the polycondensation column (3) along its length direction, and the scraper ring (19) is threaded on the outside of the threaded rod (20) so that when the threaded rod (20) rotates, the scraper ring (19) can slide along the length direction of the inner cavity of the polycondensation column (3).

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