A high-boiling closed separation device for distillation

Abstract

This utility model provides a closed-loop separation device for high-boiling-point distillation, comprising: a feed pretreatment tower; a light component separation tower connected to the feed pretreatment tower via a closed pipeline; a first reflux system located at the top of the light component separation tower; a first reboiler located at the bottom of the light component separation tower; a distillation tower connected to the bottom of the light component separation tower via a closed pipeline; a second reflux system located at the top of the distillation tower; a second reboiler located at the bottom of the distillation tower; and a side outlet on the wall of the rectification section of the distillation tower for drawing out the finished product. Through the above scheme, a dual-tower separation process is adopted, with the distillation tower employing a side-outlet structure to extract the purest material from a specific plate in the tower. This allows the product to be separated from both the light components remaining at the top of the tower and the high-boiling-point substances enriched in the bottom of the tower, significantly improving product purity.

Description

Technical Field

[0001] This utility model relates to the field of high-boiling-point separation technology, specifically to a closed separation device for high-boiling-point distillation. Background Technology

[0002] Methoxysilanes, as important intermediates for silane coupling agents, have wide applications in sealants, coatings, and plastic modification. However, the molecular structure of these compounds contains siloxane bonds that are extremely sensitive to water. During production and purification, upon contact with even trace amounts of moisture, they undergo rapid and irreversible hydrolysis, producing methanol and silanols with hydroxyl groups. Under heating conditions, the silanols may further condense to form more complex polysiloxanes.

[0003] Existing purification processes typically employ conventional single-tower distillation units. However, conventional single-tower structures struggle to simultaneously and efficiently separate methanol, which has a boiling point far lower than that of methoxysilanes, from silanols and polymers, which have a boiling point significantly higher than that of methoxysilanes. Consequently, the purity of the final product is insufficient to meet the demands of high-end applications, and the yield is relatively low. Utility Model Content

[0004] This invention provides a closed-loop distillation separation device for high-boiling points, which solves the problem that a single-tower structure cannot simultaneously separate substances with boiling points different from methoxysilane compounds.

[0005] To address the aforementioned problems, this utility model provides a high-boiling-point closed separation device for distillation, comprising: a raw material pretreatment tower; a light component separation tower connected to the raw material pretreatment tower via a closed pipeline; a first reflux system located at the top of the light component separation tower; a first reboiler located at the bottom of the light component separation tower; a distillation tower connected to the bottom of the light component separation tower via a closed pipeline; a second reflux system located at the top of the distillation tower; a second reboiler located at the bottom of the distillation tower; and a side outlet for drawing out the finished product material located on the tower wall of the rectification section of the distillation tower.

[0006] The above scheme, by setting up a raw material pretreatment unit before distillation, can deeply remove trace amounts of moisture entrained in the raw material; adopting a dual-tower separation process, the first tower is dedicated to removing low-boiling-point methanol, and the second tower is dedicated to separating high-boiling-point silanols. Furthermore, the distillation tower adopts a side-stream discharge structure, extracting the purest material from a specific plate in the tower, so that the product can be separated from the light components remaining at the top of the tower and from the high-boiling-point substances enriched in the bottom of the tower, and the product purity can be significantly improved.

[0007] According to one embodiment of the present invention, the above-mentioned raw material pretreatment tower is an adsorption tower filled with a molecular sieve layer. Through the above scheme, moisture is removed deeply by the molecular sieve adsorption tower, which can inhibit the hydrolysis reaction of methoxysilane from the source, ensuring that the material entering the subsequent light component separation tower and distillation tower is dry and stable, thereby creating the best conditions for subsequent efficient distillation separation and ensuring the high purity of the final product.

[0008] According to one embodiment of the present invention, the bottom of the pretreatment tower is connected to the inlet of the light component separation tower via a first feed pump, and the bottom of the light component separation tower is connected to the inlet of the distillation tower via a second feed pump. By setting the feed pump, the delivery rate and delivery pressure of the bottom liquid can be adjusted according to changes in operating conditions, thereby better adapting to the optimal feed requirements of the distillation tower and ensuring the stability and efficiency of the distillation process.

[0009] According to one embodiment of the present invention, the light component separation tower is equipped with a stirring device driven by a motor. Through the above scheme, the stirring device can forcibly stir the liquid material in the tower bottom or tower, so that it can come into more full and uniform contact with the rising gas phase, and be heated more uniformly, significantly increasing the area of ​​the gas-liquid interface and promoting the mass transfer rate of components between the gas and liquid phases.

[0010] According to one embodiment of the present invention, the distillation column is a packed column structure with a packing layer. Through the above scheme, the inside of the packed column is filled with a large amount of packing material, which provides a huge vapor-liquid contact surface area, so that the gas phase and the liquid phase can fully contact each other, thereby greatly promoting the mass transfer process between components.

[0011] According to one embodiment of the present invention, the side stream outlet is located above the liquid distributor inside the tower. Through the above scheme, the extracted liquid is just flowing out from the upper packing section and reaches the highest purity liquid on the tower plate after sufficient gas-liquid contact and mass transfer. This allows the extracted side stream product to be separated from the light components at the top of the tower and the high boiling points at the bottom of the tower to the maximum extent, thereby obtaining higher purity.

[0012] According to one embodiment of the present invention, the bottom of the distillation column is connected to a thin-film evaporator. With the above solution, the bottom of the distillation column is usually enriched with high-boiling-point impurities and a small amount of target products that have not been completely volatilized or are entrained. The thin-film evaporator can operate under extremely high vacuum, which reduces the boiling point of the material. Even high-boiling-point components can be evaporated and separated at a relatively low temperature, minimizing the possibility of thermal decomposition.

[0013] According to one embodiment of the present invention, the thin-film evaporator is equipped with a rotating scraper driven by a motor, and a circulation pump is also provided on the outside of the thin-film evaporator. Through the above scheme, the scraper continuously scrapes away the liquid film attached to the heating surface during rotation, exposing a new liquid film, thereby breaking the temperature and concentration gradient inside the liquid film, enhancing the heat transfer from the heating medium to the material, and maintaining efficient heat transfer even for materials with high viscosity. At the same time, through multiple cycles of evaporation, valuable light components can be separated from high-boiling-point substances to the greatest extent, thereby significantly improving the overall product recovery rate and reducing material loss.

[0014] According to one embodiment of the present invention, the separation device is connected through an inert gas protection pipeline. Through the above scheme, methoxysilane compounds are extremely sensitive to water and are prone to hydrolysis to generate silanols and alcohols. The silanols further condense to generate siloxanes. By connecting the entire separation system in an inert gas protection pipeline, the entire process from raw material entry, storage, intermediate separation and purification to finished product packaging is sealed and protected by inert gas.

[0015] The technical advantages of this application are as follows:

[0016] (1) The high-boiling closed separation device for distillation provided in this application can remove trace amounts of moisture entrained in the raw material by setting a raw material pretreatment unit before distillation; at the same time, the closed and inert gas protection design of the whole process prevents the intrusion of external moisture, inhibits the occurrence of hydrolysis reaction from the source, and ensures the stability of the material entering the separation system.

[0017] (2) The distillation high-boiling closed separation device provided in this application adopts a dual-tower separation process. The first tower is dedicated to removing low-boiling methanol, and the second tower is dedicated to separating high-boiling silanol. The distillation tower adopts a side-stream discharge structure, which extracts the purest material from a specific plate in the tower, so that the product can be separated from the light components remaining at the top of the tower and from the high-boiling substances enriched in the bottom of the tower, and the product purity can be significantly improved.

[0018] (3) The high-boiling closed separation device for distillation provided in this application, with its dual-tower fine separation and side-stream discharge method, avoids the uniformity of single-tower separation and reduces the overall reflux ratio and energy consumption. At the same time, the thin-film evaporator of the high-boiling matter treatment unit is set in the bottom of the tower, which can recover the small amount of product entrained in the high-boiling matter, further improving the overall yield and reducing the production cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a high-boiling closed separation device for distillation provided by this utility model.

[0020] Figure 2This is a top view structural diagram of the downcomer tray of a high-boiling closed separation device for distillation provided by this utility model.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Raw material inlet; 2. Raw material pretreatment tower; 201. Molecular sieve layer; 3. Light component separation tower; 301. Stirring device; 4. First reflux condenser system; 5. First reboiler; 7. Distillation tower; 701. Liquid distributor; 702. Packing layer; 8. Second reflux condenser system; 9. Second reboiler; 10. Side outlet; 12. Thin film evaporator; 1201. Rotary scraper; 1202. Circulation pump; 13. First feed pump; 14. Second feed pump. Detailed Implementation

[0023] The following will be combined with the appendix Figures 1-2 The embodiments of the technical solution of this application are described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples and should not be used to limit the scope of protection of this application.

[0024] Reference Figure 1 and Figure 2 This utility model provides a high-boiling closed separation device for distillation, comprising: a raw material pretreatment tower 2, a light component separation tower 3 connected to the raw material pretreatment tower 2 via a closed pipeline, a first condensation reflux system 4 located at the top of the light component separation tower 3, a first reboiler 5 located at the bottom of the light component separation tower 3, a distillation tower 7 connected to the bottom of the light component separation tower 3 via a closed pipeline, a second condensation reflux system 8 located at the top of the distillation tower 7, a second reboiler 9 located at the bottom of the distillation tower 7, and a side outlet 10 located on the wall of the rectification section of the distillation tower 7 for leading out the finished product.

[0025] The above scheme utilizes a pre-treatment unit for raw materials before distillation to effectively remove trace amounts of moisture. A dual-tower separation process is employed: the first tower is dedicated to removing low-boiling-point methanol, and the second tower is dedicated to separating high-boiling-point silanols. Crucially, the product distillation tower 7 employs a side-stream discharge structure, extracting the purest material from specific plates within the tower. This ensures that the product is separated from both the light components remaining at the top of the tower and the high-boiling-point substances enriched in the bottom, significantly improving product purity.

[0026] The minimum theoretical number of plates for the feed plate layer was determined by the Finsker equation, the actual number of plates was determined by the Gilliland correlation diagram, and finally the final feed plate layer was verified by Aspen Plus simulation. A flanged nozzle was welded to the column wall at a specified height in the region between the top of distillation column 7 and the feed inlet. (Refer to...) Figure 2The nozzle is internally connected to the downcomer 703 of the downcomer tray 704. Externally, a manual shut-off ball valve, a Y-type filter, a Coriolis mass flow meter, and a pneumatic regulating valve (not shown in the diagram) are connected in sequence to the nozzle. The flow meter signal is sent to the controller, which issues commands to control the opening of the regulating valve. The entire pipeline is made of 316L stainless steel and is covered with electric heating tape and insulation.

[0027] The aforementioned raw material pretreatment tower 2 is an adsorption tower filled with a molecular sieve layer 201. Through the above scheme, moisture is removed deeply by the molecular sieve adsorption tower, which can inhibit the hydrolysis reaction of methoxysilane from the source, ensuring that the material entering the subsequent light component separation tower 3 and distillation tower 7 is dry and stable, thereby creating the best conditions for subsequent efficient distillation separation and ensuring the high purity of the final product.

[0028] The bottom of the pretreatment column is connected to the inlet of the light component separation column 3 via a first feed pump 13. The bottom of the light component separation column 3 is connected to the inlet of the distillation column 7 via a second feed pump 14. By setting up the feed pumps, the delivery rate and pressure of the bottom liquid can be adjusted according to changes in operating conditions, thereby better adapting to the optimal feed requirements of the distillation column 7 and ensuring the stability and efficiency of the distillation process.

[0029] The light component separation tower 3 is equipped with a stirring device 301 driven by a motor. Through the above scheme, the stirring device 301 can forcibly stir the liquid material in the tower bottom or tower. The stirring device 301 is used to process high viscosity materials with a viscosity greater than 50 mPa·s, and the stirring speed is controlled at 30-60 rpm, so that it can have more full and uniform contact with the rising gas phase, and be heated more uniformly. This significantly increases the area of ​​the gas-liquid interface and promotes the mass transfer rate of components between the gas and liquid phases.

[0030] The distillation column 7 described above is a packed column structure with a packing layer 702. Through the above scheme, the inside of the packed column is filled with a large amount of packing material, which provides a huge vapor-liquid contact surface area, allowing the gas phase and liquid phase to fully contact each other, thereby greatly promoting the mass transfer process between components.

[0031] The aforementioned side stream outlet 10 is located above the liquid distributor 701 inside the tower. Through the above scheme, the extracted liquid is the liquid that has just flowed out from the upper packing section and has reached the highest purity liquid on the tower plate after sufficient gas-liquid contact and mass transfer. This allows the extracted side stream product to be separated from the light components at the top of the tower and the high boiling points at the bottom of the tower to the maximum extent, thereby obtaining the highest purity.

[0032] The distillation column 7 is connected to a thin-film evaporator 12. With the above scheme, the bottom of the distillation column 7 is usually enriched with high-boiling-point impurities and a small amount of target products that have not been completely volatilized or are entrained. The thin-film evaporator 12 can operate under extremely high vacuum, which reduces the boiling point of the material. Even high-boiling-point components can be evaporated and separated at a relatively low temperature, minimizing the possibility of thermal decomposition.

[0033] The aforementioned thin-film evaporator 12 is equipped with a rotating scraper 1201 driven by a motor, and a circulating pump 1202 is also provided on the outside of the thin-film evaporator 12. Through the above scheme, the scraper continuously scrapes away the liquid film attached to the heating surface during rotation, exposing a new liquid film, thereby breaking the temperature and concentration gradient inside the liquid film and enhancing the heat transfer from the heating medium to the material. Even materials with high viscosity can maintain efficient heat transfer. At the same time, the circulating pump 1202 has a flow rate of 15 m³ / h, a head of 2.5 m, and is made of 316L stainless steel. Through multiple cycles of evaporation, valuable light components can be separated from high-boiling-point substances to the greatest extent, thereby significantly improving the overall product recovery rate and reducing material loss.

[0034] The aforementioned separation devices are connected via inert gas protection pipelines. Through this scheme, methoxysilane compounds are extremely sensitive to water and readily undergo hydrolysis to generate silanols and alcohols. The silanols further condense to form siloxanes. By connecting the entire separation system to inert gas protection pipelines, using nitrogen gas with a purity ≥99.999%, and maintaining the protection pressure at 0.3±0.02MPa, the nitrogen flow rate to raw material feed rate is 1:1. Online oxygen content analyzers (not shown in the figure) are installed at the inlet and various outlets of the raw material pretreatment tower 2. An audible and visual alarm is triggered when the oxygen content >5ppm. Each equipment unit is equipped with a pressure relief valve, achieving a fully enclosed and inert gas-protected process from raw material entry, storage, intermediate separation and purification to finished product packaging.

[0035] Working principle:

[0036] First, during startup, the crude methoxysilane raw material to be purified is pumped and enters the raw material pretreatment tower 2, which is filled with 3A molecular sieve, from the raw material inlet 1. In this pretreatment tower, any trace amounts of moisture that may be present in the raw material are removed.

[0037] The dried raw material, after dehydration, is fed into the middle of the light component separation tower 3 via the first feed pump 13. The first reboiler 5 in the tower bottom provides heat to vaporize the material. The vapor from the top of the tower enters the first condensate reflux system 4. Most of the condensate is returned to the top of the tower as reflux, while a small portion of the light components (mainly methanol generated from hydrolysis) is extracted and sent to the alcohol collection tank. By controlling the reflux ratio and the top temperature of the tower, it is ensured that low-boiling-point impurities such as methanol are completely separated.

[0038] After preliminary purification and removal of light components by the light component separation tower 3, the material is drawn from the bottom of the tower and sent to the middle of the distillation tower 7 by the second feed pump 14. The bottom of the distillation tower 7 is heated by the second reboiler 9, and the top vapor enters the second condensation reflux system 8. All the condensate is refluxed back to the top of the tower to ensure that the product is not lost with the vapor phase.

[0039] The high-purity methoxysilane product is not obtained from the top or bottom of the column. Instead, in the rectification section of the distillation column 7, specifically the area between the top and the feed inlet, a tray with the highest target product concentration is selected and designated as a downcomer tray 704. The downcomer 703 is connected to the side outlet 10 via a nozzle. The liquid phase material, which is the high-purity finished product, is drawn out through this outlet and then sent to the sealed finished product storage tank 11.

[0040] Furthermore, residual impurities with boiling points lower than the target product will continue to migrate towards the top of the column, while silanols and polymers with boiling points higher than the target product will accumulate in the bottom of the column. Discharging from the middle side stream avoids these two types of impurities, thus obtaining the product with the highest purity.

[0041] The high-boiling-point substances enriched in the bottom of distillation column 7 are fed into an external thin-film evaporator 12, where a small amount of the target product entrained therein is distilled off and recovered into the system under vacuum and high temperature, while the remaining residue is sent to a high-boiling-point substance collection tank.

[0042] The entire system, including all storage tanks and pipelines, is connected by an inert gas (such as nitrogen) pipeline network (not shown) to maintain a slight positive pressure and prevent the intrusion of external air and moisture.

[0043] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A closed distillation separation device for high-boiling points, characterized in that, include: The raw material pretreatment tower (2), the light component separation tower (3) connected to the raw material pretreatment tower (2) through a closed pipeline, the first condensation reflux system (4) located at the top of the light component separation tower (3), the first reboiler (5) located at the bottom of the light component separation tower (3), the distillation tower (7) connected to the bottom of the light component separation tower (3) through a closed pipeline, the second condensation reflux system (8) located at the top of the distillation tower (7), the second reboiler (9) located at the bottom of the distillation tower (7), and the side outlet (10) located on the wall of the distillation section of the distillation tower (7) for drawing out the finished product material.

2. The high-boiling-point closed separation device for distillation according to claim 1, characterized in that, The raw material pretreatment tower (2) is an adsorption tower filled with a molecular sieve layer (201).

3. The high-boiling-point closed separation device for distillation according to claim 1, characterized in that, The bottom of the pretreatment tower (2) is connected to the inlet of the light component separation tower (3) via a first feed pump (13), and the bottom of the light component separation tower (3) is connected to the inlet of the distillation tower (7) via a second feed pump (14).

4. The high-boiling-point closed separation device for distillation according to claim 1, characterized in that, The light component separation tower (3) is equipped with a stirring device (301) driven by a motor.

5. The high-boiling-point closed separation apparatus for distillation according to claim 1, characterized in that, The distillation column (7) is a packed column structure with a packing layer (702).

6. The high-boiling-point closed separation apparatus for distillation according to claim 5, characterized in that, The side outlet (10) is located above the liquid distributor (701) inside the tower.

7. The high-boiling-point closed separation apparatus for distillation according to claim 1, characterized in that, The distillation column (7) is connected to a thin-film evaporator (12) in its bottom.

8. The high-boiling-point closed separation apparatus for distillation according to claim 7, characterized in that, The thin film evaporator (12) is equipped with a rotating scraper (1201) driven by a motor, and a circulating pump (1202) is also provided on the outside of the thin film evaporator (12).

9. The high-boiling-point closed separation apparatus for distillation according to claim 1, characterized in that, The separation device is connected via an inert gas protection pipeline.

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