A device for synthesizing dioctyl terephthalate
By using anhydrous octanol as the reflux liquid in the dioctyl terephthalate synthesis apparatus and combining it with sensor monitoring, the problem of low efficiency in the initial stage of the esterification reaction was solved, and a highly efficient esterification reaction of terephthalic acid and octanol was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- KAIFENG JIUHONG CHEM CO LTD
- Filing Date
- 2025-06-24
- Publication Date
- 2026-07-14
AI Technical Summary
Existing dioctyl terephthalate synthesis devices suffer from slow esterification reaction rates and low efficiency. In particular, the low reflux octanol temperature in the early stages of the esterification reaction leads to a decrease in the reaction temperature, which affects the reaction progress.
An improved synthesis apparatus is used, which uses anhydrous octanol as the reflux liquid to replace the traditional liquefied octanol. The reflux liquid is transported through the bottom of a distillation column and the liquefied octanol is temporarily stored in a reflux liquid storage tank to increase the reactant concentration and reduce the water content. Combined with a steam delivery pipe and sensors to monitor reaction parameters, the esterification reaction is ensured to proceed stably.
This improved the efficiency of the esterification reaction of terephthalic acid and octanol, solved the problem of insufficient octanol phase in the early stage of the esterification reaction, and achieved a more efficient esterification reaction process.
Smart Images
Figure CN224485941U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of equipment for synthesizing dioctyl terephthalate, and specifically to a method for synthesizing dioctyl terephthalate. Background Technology
[0002] The mainstream process for synthesizing dioctyl terephthalate (DTP) involves heating terephthalic acid and isooctyl alcohol under the action of a catalyst. The reaction principle is esterification. According to the principles of esterification, increasing the concentration of the reactants and decreasing the concentration of the products promotes the forward reaction. Since water is present in the esterification products, it is necessary to control the water content in the reaction system during the initial stage to ensure the forward esterification reaction. Specifically, the DTP reaction is a series of reactions: first, terephthalic acid reacts with octyl alcohol to form monooctyl terephthalate; second, monooctyl terephthalate reacts with octyl alcohol to form dioctyl terephthalate. The first step is relatively slow, while the second step is relatively fast. To improve the overall esterification synthesis progress, controlling the water content of the reflux solution in the early stages is essential.
[0003] Since the esterification reaction itself requires heating, and in industrial production, the octanol contained in the steam emitted from the top of the reactor is condensed and returned to the reactor, the low temperature of the refluxed octanol lowers the overall reaction temperature. Increasing the temperature of the octanol returning to the reactor reduces the temperature drop caused by the reflux, thus facilitating the esterification reaction. Therefore, there is room for improvement in the existing technology for the synthesis of dioctyl terephthalate, aiming to increase the rate of the esterification reaction and improve production efficiency. Summary of the Invention
[0004] In view of the shortcomings of the prior art, this utility model provides a synthesis apparatus for dioctyl terephthalate that can improve the esterification reaction efficiency of dioctyl terephthalate, thereby overcoming the defects in the prior art.
[0005] The technical solution adopted by this utility model is as follows: a synthesis apparatus for dioctyl terephthalate, including a reaction vessel, wherein the reaction vessel is provided with an inlet end of a first steam conveying pipe and an outlet end of a reflux liquid conveying pipe, and a distillation column is provided on the outlet end of the first steam conveying pipe and the inlet end of the reflux liquid conveying pipe. A packing layer is provided in the distillation column above the first steam conveying pipe and the reflux liquid conveying pipe. A first regulating valve, a first shut-off valve, a first check valve, and a cold source channel of a first heat exchanger are sequentially provided on the reflux liquid conveying pipe from the distillation column to the reaction vessel. The reflux liquid conveying pipe between the first regulating valve and the first shut-off valve is connected to a reflux liquid storage tank. An octanol storage tank is provided on one side of the reflux liquid storage tank. An alcohol conveying pipe is provided on the octanol storage tank. A second shut-off valve, a first booster pump, and a second check valve are sequentially provided on the alcohol conveying pipe from the octanol storage tank to the reflux liquid conveying pipe.
[0006] Preferably, the number of reflux liquid storage tanks is several, and each reflux liquid storage tank and reflux liquid delivery pipe are respectively connected through a first delivery branch pipe. The bottom of each reflux liquid storage tank and the alcohol delivery pipe between the second shut-off valve and the first booster pump are connected through a second delivery branch pipe. The bottom of each reflux liquid storage tank is also provided with the inlet end of a third delivery branch pipe. The outlet ends of several third delivery branch pipes are provided with the inlet end of a first condensate delivery pipe. The outlet end of the first condensate delivery pipe is connected to the distillation column above the packing layer. The first condensate delivery pipe is provided with the heat source channels of the second booster pump and the second heat exchanger in sequence along the direction from near the distillation column to far away from the distillation column. A fourth shut-off valve is provided on each of the several first delivery branch pipes, several second delivery branch pipes and several third delivery branch pipes.
[0007] Preferably, the octanol storage tank, the reaction vessel, the several reflux liquid storage tanks, and the distillation column below the packing layer are all equipped with level sensors, and each reflux liquid storage tank is equipped with an exhaust valve.
[0008] Preferably, the first steam delivery pipe is provided with a humidity sensor, a first temperature sensor, a first pressure sensor, a second regulating valve, a gas flow sensor, and a second pressure sensor in sequence along the direction from the reactor to the distillation column.
[0009] Preferably, a third temperature sensor and a liquid flow sensor are installed on the reflux liquid delivery pipe between the first heat exchanger and the reactor.
[0010] Preferably, the distillation column above the packing layer is connected to the inlet end of the heat source channel of the third heat exchanger, the outlet end of the heat source channel of the third heat exchanger is provided with the inlet end of the cyclone separator, the liquid phase outlet end of the cyclone separator is connected to the inlet end of the phase separator, the water phase outlet end of the phase separator is provided with a drain pipe, the drain pipe is provided with a third regulating valve, and the organic phase outlet end of the phase separator and the distillation column above the packing layer are connected through a U-shaped liquid seal pipe.
[0011] The beneficial effects of this invention are as follows: First, in the esterification reaction of terephthalic acid and octanol, the reaction rate is slow and unstable in the early stage because terephthalic acid and octanol first form monooctyl terephthalate. In this invention, anhydrous octanol is used as the reflux liquid in the reaction vessel to replace the liquefied octanol transported from the bottom of the distillation column in the traditional process. This increases the concentration of reactants and reduces the water content as a product in the early stage of the esterification reaction of terephthalic acid and octanol, which is conducive to the esterification reaction of terephthalic acid and octanol and effectively improves the reaction efficiency of terephthalic acid and octanol. Furthermore, this product uses the liquefied octanol temporarily stored in the reflux liquid storage tank as the condensate reflux liquid in the distillation column, overcoming the technical problem that the insufficient octanol phase in the phase separator in the early stage of the esterification reaction cannot normally provide condensate reflux liquid to the distillation column. This invention is worthy of widespread application.
[0012] Secondly, the first steam conveying pipe of this utility model is sequentially equipped with a humidity sensor, a first temperature sensor, a first pressure sensor, a second regulating valve, a gas flow sensor, and a second pressure sensor along the direction from the reactor to the distillation column; the installation of the first temperature sensor facilitates the feedback of temperature parameters; the installation of the humidity sensor facilitates the feedback of moisture parameters; the installation of the first pressure sensor and the second pressure sensor facilitates the feedback of pressure parameters; and the installation of the gas flow sensor facilitates the feedback of gas flow parameters.
[0013] Furthermore, level sensors are installed on the octanol storage tank, the reaction vessel, several reflux liquid storage tanks, and the distillation column below the packing layer of this utility model. Installing level sensors facilitates the feedback of liquid level parameters.
[0014] This utility model has a simple structure, is easy to operate, and has a clever design, which greatly improves work efficiency and has good social and economic benefits. It is a product that is easy to promote and use. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation
[0016] like Figure 1As shown, an apparatus for synthesizing dioctyl terephthalate includes a reactor 1. The reactor 1 is provided with an inlet end of a first steam delivery pipe 2 and an outlet end of a reflux liquid delivery pipe 3. A distillation column 4 is installed at the outlet end of the first steam delivery pipe 2 and the inlet end of the reflux liquid delivery pipe 3. A packing layer 5 is provided inside the distillation column 4 above the first steam delivery pipe 2 and the reflux liquid delivery pipe 3. A first regulating valve is sequentially installed along the reflux liquid delivery pipe 3 from the distillation column 4 to the reactor 1. 6. The cold source passage of the first shut-off valve 7, the first check valve 8, and the first heat exchanger 9; the reflux liquid conveying pipe 3 between the first regulating valve 6 and the first shut-off valve 7 is connected to the reflux liquid storage tank 10; an octanol storage tank 11 is provided on one side of the reflux liquid storage tank 10; an alcohol liquid conveying pipe 12 is provided on the octanol storage tank 11; and a second shut-off valve 13, a first booster pump 14, and a second check valve 15 are sequentially provided on the alcohol liquid conveying pipe 12 along the direction from the octanol storage tank 11 to the reflux liquid conveying pipe 3.
[0017] The reflux liquid storage tanks 10 are of several types. Each reflux liquid storage tank 10 is connected to the reflux liquid delivery pipe 3 through a first delivery branch pipe 16. The bottom of each reflux liquid storage tank 10 and the alcohol delivery pipe 12 between the second shut-off valve 13 and the first booster pump 14 are connected through a second delivery branch pipe 17. The bottom of each reflux liquid storage tank 10 is also provided with the inlet end of a third delivery branch pipe 18. The outlet ends of several third delivery branch pipes 18 are provided with the inlet ends of a first condensate delivery pipe 19. The outlet end of the first condensate delivery pipe 19 is connected to the distillation column 4 above the packing layer 5. The first condensate delivery pipe 19 is provided with the heat source channels of the second booster pump 20 and the second heat exchanger 21 in sequence along the direction from near to far from the distillation column 4. A fourth shut-off valve 22 is provided on each of the several first delivery branch pipes 16, several second delivery branch pipes 17 and several third delivery branch pipes 18. This allows one reflux tank 10 to receive the bottom condensate from the distillation column 4, while another reflux tank 10 stores the bottom condensate to supply condensate to the distillation column 4 above the packing layer 5. This overcomes the problem that in the early stages of the esterification reaction, due to the small amount of steam, the phase separator 35 cannot properly supply condensate to the packing layer 5 for the steam entering the packing layer 5 to perform countercurrent heat exchange.
[0018] Level sensors 23 are installed on the octanol storage tank 11, the reactor 1, several reflux liquid storage tanks 10, and the distillation column 4 below the packing layer 5. The installation of level sensors 23 facilitates the feedback of liquid level parameters. Each reflux liquid storage tank 10 is equipped with an exhaust valve 24. A humidity sensor 25, a first temperature sensor 26, a first pressure sensor 27, a second regulating valve 28, a gas flow sensor 29, and a second pressure sensor 30 are sequentially installed along the direction from the reactor 1 to the distillation column 4 on the first steam delivery pipe 2. A third temperature sensor 31 and a liquid flow sensor 32 are installed on the reflux liquid delivery pipe 3 between the first heat exchanger 9 and the reactor 1.
[0019] The distillation column 4 above the packing layer 5 is connected to the inlet end of the heat source channel of the third heat exchanger 33. The outlet end of the heat source channel of the third heat exchanger 33 is equipped with the inlet end of the cyclone separator 34. The liquid phase outlet end of the cyclone separator 34 is connected to the inlet end of the phase separator 35. The aqueous phase outlet end of the phase separator 35 is equipped with a drain pipe 36, and a third regulating valve 37 is installed on the drain pipe 36. The organic phase outlet end of the phase separator 35 and the distillation column 4 above the packing layer 5 are connected through a U-shaped liquid seal pipe 38. A second condensate delivery pipe 39 is provided between the inlet end of the U-shaped liquid seal pipe 38 and the phase separator 35. A fourth regulating valve 40 is installed on the second condensate delivery pipe 39.
[0020] The instructions for using this product are as follows: Figure 1As shown, raw materials and catalysts are added to reactor 1, and then heat transfer oil is supplied to the jacket of reactor 1 to raise the temperature of the inner cavity of reactor 1. The raw materials undergo esterification reaction under the action of catalyst. During this period, reactor 1 continuously supplies first steam to the outside through first steam delivery pipe 2. The first steam includes inert gas, water vapor, octanol vapor and non-condensable gas. The first steam is delivered to distillation column 4 and continues to rise along the inner cavity of distillation column 4. At the same time, one of the reflux liquid storage tanks 10 continuously supplies reflux condensate to distillation column 4 above packing layer 5 through first condensate delivery pipe 19. The reflux condensate is pressurized by second booster pump 20 and delivered to the heat source channel of second heat exchanger 21 and the circulating water continuously delivered to the cold source channel of second heat exchanger 21 for countercurrent heat exchange. During this period, anhydrous octanol needs to be continuously replenished into the reactor 1 due to the emission of the first steam, so that the concentration of reactants in the esterification reaction is always maintained within a preset range. The replenished anhydrous octanol is provided by the anhydrous octanol stored in the octanol storage tank 11. After the first booster pump 14 is turned on, the anhydrous octanol is transported to the reflux liquid transport pipe 3 through the alcohol supply pipe 12. The anhydrous octanol is heat-exchanged through the cold source channel of the first heat exchanger 9 and the heat transfer oil of the continuous heat source channel of the first heat exchanger 9. After the temperature is fed back by the third temperature sensor 31 and the flow rate is fed back by the liquid flow sensor 32, it is transported to the reactor 1 as the reflux liquid of the reactor 1.
[0021] The first vapor and reflux condensate undergo countercurrent heat exchange within the distillation column 4. The octanol component in the first vapor is liquefied and flows downwards along with the reflux condensate, while the water component in the reflux condensate is vaporized by the first vapor and flows upwards towards the top of the distillation column 4 along with the first vapor. A liquefied octanol enrichment zone is formed at the bottom of the distillation column 4. This enrichment zone continuously supplies liquefied octanol to another reflux storage tank 10. During this process, the flow rate of liquefied octanol needs to be adjusted based on the level parameters fed back by the level sensor 23 on the distillation column 4. Meanwhile, the top of the distillation column 4 continuously supplies a second steam, which includes inert gas, water vapor, a small amount of octanol vapor, and non-condensable gas. The second steam is supplied to the heat source channel of the third heat exchanger 33 and the circulating water continuously supplied to the cold source channel of the third heat exchanger 33 for countercurrent heat exchange. The water vapor and the small amount of octanol vapor in the second steam are liquefied to form the liquid phase component of the second steam, while the inert gas and non-condensable gas in the second steam remain in a gaseous state to form the gaseous phase component of the second steam. After being discharged from the heat source channel of the third heat exchanger 33, the second steam is supplied to the cyclone separator 34 for gas-liquid separation. The gaseous phase component of the second steam is discharged through the gas phase outlet end of the cyclone separator 34, while the liquid phase component of the second steam is supplied to the phase separator 35.
[0022] As the reaction continues, the liquid level in the phase separator 35 continues to rise, and the octanol phase in the phase separator 35 also gradually increases. After both the liquid level in the phase separator 35 and the liquid level of the octanol phase reach the preset range, the continuous supply of reflux condensate to the distillation column 4 above the packing layer 5 through the first condensate delivery pipe 19 is stopped. At the same time, the fourth regulating valve 40 is opened to continuously supply the octanol phase in the phase separator 35 to the distillation column 4 above the packing layer 5 to replace the reflux condensate and the first vapor for countercurrent heat exchange in the distillation column 4.
[0023] As the reaction progresses, the value fed back by the humidity sensor 25 tends to stabilize. When the value fed back by the humidity sensor 25 stabilizes and the reaction in reactor 1 reaches the preset time, the fourth shut-off valve 22, the second shut-off valve 13 and the first booster pump 14 on the corresponding second delivery branch pipe 17 are closed and the first shut-off valve 7 is opened. At this time, the liquefied octanol enrichment zone at the bottom of the distillation column 4 continuously supplies liquefied octanol to reactor 1 to replace anhydrous octanol as the reflux liquid of reactor 1 until the esterification reaction ends.
[0024] In this embodiment, during the esterification reaction of terephthalic acid and octanol, the initial reaction rate is slow and unstable because terephthalic acid and octanol first form monooctyl terephthalate. This product utilizes anhydrous octanol as the reflux liquid in reaction vessel 1 instead of the liquefied octanol supplied from the bottom of distillation column 4 in the traditional process. This increases the concentration of reactants and reduces the water content as a product in the early stages of the esterification reaction, which is beneficial to the esterification reaction and effectively improves the reaction efficiency. Furthermore, this product uses liquefied octanol temporarily stored in reflux tank 10 as the condensate reflux liquid in distillation column 4, overcoming the technical problem of insufficient octanol phase in phase separator 35 during the early stages of the esterification reaction, which prevents the normal supply of condensate reflux liquid to distillation column 4. This method is worthy of widespread application.
[0025] The embodiments described above are merely preferred embodiments of this utility model and are not intended to limit the scope of implementation of this utility model. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the patent claims of this utility model should be included within the scope of the patent application of this utility model.
Claims
1. An apparatus for synthesizing dioctyl terephthalate, characterized in that: The reactor includes a reactor (1), which is provided with an inlet end of a first steam conveying pipe (2) and an outlet end of a reflux liquid conveying pipe (3). A distillation column (4) is provided on the outlet end of the first steam conveying pipe (2) and the inlet end of the reflux liquid conveying pipe (3). A packing layer (5) is provided in the distillation column (4) above the first steam conveying pipe (2) and the reflux liquid conveying pipe (3). A first regulating valve (6) and a first shut-off valve (7) are sequentially provided on the reflux liquid conveying pipe (3) along the direction from the distillation column (4) to the reactor (1). The first one-way valve (8), the cold source channel of the first heat exchanger (9), the reflux liquid conveying pipe (3) between the first regulating valve (6) and the first shut-off valve (7) are connected to the reflux liquid storage tank (10). An octanol storage tank (11) is provided on one side of the reflux liquid storage tank (10). An alcohol conveying pipe (12) is provided on the octanol storage tank (11). A second shut-off valve (13), a first booster pump (14) and a second one-way valve (15) are sequentially provided on the alcohol conveying pipe (12) along the direction from the octanol storage tank (11) to the reflux liquid conveying pipe (3).
2. The apparatus for synthesizing dioctyl terephthalate according to claim 1, characterized in that: The number of reflux liquid storage tanks (10) is several. Each reflux liquid storage tank (10) and reflux liquid delivery pipe (3) are connected by a first delivery branch pipe (16). The bottom of each reflux liquid storage tank (10) and the alcohol delivery pipe (12) between the second shut-off valve (13) and the first booster pump (14) are connected by a second delivery branch pipe (17). The bottom of each reflux liquid storage tank (10) is also provided with the inlet end of a third delivery branch pipe (18), and the outlet ends of several third delivery branch pipes (18) are provided. The inlet end of the first condensate delivery pipe (19) is provided, and the outlet end of the first condensate delivery pipe (19) is connected to the distillation column (4) above the packing layer (5). The first condensate delivery pipe (19) is provided with the heat source channels of the second booster pump (20) and the second heat exchanger (21) in sequence along the direction from near the distillation column (4) to far away from the distillation column (4). A fourth shut-off valve (22) is provided on several first delivery branch pipes (16), several second delivery branch pipes (17) and several third delivery branch pipes (18).
3. The apparatus for synthesizing dioctyl terephthalate according to claim 1, characterized in that: Level sensors (23) are installed on the octanol storage tank (11), the reactor (1), several reflux liquid storage tanks (10) and the distillation column (4) below the packing layer (5), and an exhaust valve (24) is installed on each reflux liquid storage tank (10).
4. The apparatus for synthesizing dioctyl terephthalate according to claim 1, characterized in that: The first steam delivery pipe (2) is provided with a humidity sensor (25), a first temperature sensor (26), a first pressure sensor (27), a second regulating valve (28), a gas flow sensor (29), and a second pressure sensor (30) in sequence along the direction from the reactor (1) to the distillation column (4).
5. The apparatus for synthesizing dioctyl terephthalate according to claim 1, characterized in that: A third temperature sensor (31) and a liquid flow sensor (32) are installed on the reflux liquid delivery pipe (3) between the first heat exchanger (9) and the reactor (1).
6. The apparatus for synthesizing dioctyl terephthalate according to claim 1, characterized in that: The distillation column (4) above the packing layer (5) is connected to the inlet end of the heat source channel of the third heat exchanger (33). The outlet end of the heat source channel of the third heat exchanger (33) is provided with the inlet end of the cyclone separator (34). The liquid phase outlet end of the cyclone separator (34) is connected to the inlet end of the phase separator (35). The water phase outlet end of the phase separator (35) is provided with a drain pipe (36). The drain pipe (36) is provided with a third regulating valve (37). The organic phase outlet end of the phase separator (35) and the distillation column (4) above the packing layer (5) are connected through a U-shaped liquid seal pipe (38).