A coupled rectification separation system and a coupled rectification separation method

Abstract

The application provides a coupled rectification separation system and a coupled rectification separation method. The coupled rectification separation system comprises a first rectification tower, a second rectification tower, a reflux tank, a tower top communication pipe and a tower top control valve. The outlet of the first rectification tower is communicated with the inlet of the second rectification tower. The reflux tank is communicated with the tower top of the second rectification tower through the tower top communication pipe. The tower top control valve is arranged on the tower top communication pipe. The separation system can flexibly adjust the tower top pressure of the second rectification tower.

Description

Technical Field

[0001] This invention relates to a coupled distillation separation system and a coupled distillation separation method, belonging to the field of chemical separation technology. Background Technology

[0002] In chemical production, multiple distillation columns are often connected in series to separate multi-component mixtures, or to improve the separation accuracy of products. Figure 1 This refers to a coupled distillation separation system in existing technology. For example... Figure 1 As shown, taking any two interconnected distillation columns as an example, the existing coupled distillation separation system includes a first distillation column 1, a second distillation column 2, a reboiler 3, a reflux tank 7, a pressure relief unit, a liquid discharge valve 4, a pressurization unit, a liquid phase delivery pipe 10, and a gas phase delivery pipe 8. The bottom liquid outlet of the first distillation column 1 is connected to the liquid phase inlet of the reboiler 3, the top gas phase outlet of the second distillation column 2 is connected to the gas phase inlet of the reboiler 3, the first liquid phase outlet of the reboiler 3 is connected to the liquid phase inlet of the reflux tank 7 via the liquid phase delivery pipe 10, the liquid discharge valve 4 is located above the liquid phase delivery pipe 10, the reboiler 3 and the reflux tank 7 are also connected via the gas phase delivery pipe 8, the pressure relief unit and the pressurization unit are respectively connected to the reflux tank 7, a vent valve 5 is installed on the connecting pipe between the pressure relief unit and the reflux tank 7, and a hydrogen valve 6 is installed on the connecting pipe between the pressurization unit and the reflux tank 7. In actual operation, on the one hand, the heat exchange area of ​​the reboiler 3 is controlled by controlling the opening and closing of the liquid discharge valve 4, thereby regulating the pressure at the top of the second distillation column 2; on the other hand, the pressure at the top of the second distillation column 2 is regulated by controlling the opening and closing of the liquid discharge valve 4, the vent valve 5 and the hydrogen valve 6 respectively.

[0003] However, in practical applications, adjusting the top pressure of the second distillation column 2 through the vent valve 5, the liquid discharge valve 4, and the hydrogen valve 6 has a delay and interference, low adjustment sensitivity, and improper operation can easily cause the top pressure of the second distillation column 2 to be difficult to adjust or to fluctuate significantly, which is not only detrimental to the separation of raw materials, but also can cause safety problems. Summary of the Invention

[0004] The present invention provides a coupled distillation separation system that can flexibly adjust the top pressure of the second distillation column.

[0005] This invention provides a coupled distillation separation method, which uses the above-mentioned coupled distillation separation system and can flexibly adjust the top pressure of the second distillation column.

[0006] The present invention provides a coupled distillation separation system, comprising a first distillation column, a second distillation column, a reflux tank, a top connecting pipe, and a top control valve;

[0007] The outlet of the first distillation column is connected to the inlet of the second distillation column, the reflux tank is connected to the top of the second distillation column through the top connecting pipe, and the top control valve is located on the top connecting pipe.

[0008] The coupled distillation separation system described above further includes a pressurization unit connected to the reflux tank.

[0009] The coupled distillation separation system described above, wherein the pressurization unit includes a hydrogen pressurization unit and / or a nitrogen pressurization unit.

[0010] The coupled distillation separation system described above further includes a pressure relief unit connected to the reflux tank.

[0011] The coupled distillation separation system described above further includes a reboiler disposed in the bottom of the first distillation column.

[0012] The coupled distillation separation system described above further includes a liquid phase delivery pipe;

[0013] The bottom of the first distillation column is connected to the liquid phase inlet of the reboiler, the top of the second distillation column is connected to the gas phase inlet of the reboiler, and the liquid phase outlet of the reboiler is connected to the reflux tank through the liquid phase delivery pipe.

[0014] The coupled distillation separation system described above further includes a gas phase delivery pipe;

[0015] The gas phase outlet of the reboiler is connected to the reflux tank via the gas phase delivery pipe.

[0016] The coupled distillation separation system described above further includes a gas phase valve; the gas phase valve is disposed on the gas phase delivery pipe.

[0017] In the coupled distillation separation system described above, the reboiler and the reflux tank are located on the same plane.

[0018] The present invention also provides a coupled distillation separation method, wherein the coupled distillation separation system described above is used.

[0019] This invention provides a coupled distillation separation system. The separation system uses a top connecting pipe to connect the reflux tank to the top of the second distillation column, and a top control valve is installed on the top connecting pipe. The top control valve is used to control the top pressure of the second distillation column in real time, eliminating the delay in the control process and improving the control sensitivity.

[0020] This invention provides a coupled distillation separation method using the aforementioned coupled distillation separation system. Therefore, it can control the top pressure of the second distillation column in real time, and is simple to operate, making it suitable for widespread application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a coupled distillation separation system in the prior art;

[0023] Figure 2 This is a coupled distillation separation system in some embodiments of the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1: First distillation column;

[0026] 2: Second distillation column;

[0027] 3: Reboiler;

[0028] 4: Drain valve;

[0029] 5: Vent valve;

[0030] 6: Hydrogen valve;

[0031] 7: Reflux tank;

[0032] 8: Gas phase delivery pipe;

[0033] 9: Pressure detection unit;

[0034] 10: Liquid phase delivery pipe;

[0035] 11: Nitrogen valve;

[0036] 12: Gas phase valve;

[0037] 13: Tower top connecting pipe;

[0038] 14: Tower top control valve. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Figure 2 This refers to a coupled distillation separation system in some embodiments of the present invention. For example... Figure 2 As shown, the present invention provides a coupled distillation separation system, including a first distillation column 1, a second distillation column 2, a reflux tank 7, a column top connecting pipe 13, and a column top control valve 14;

[0041] The outlet of the first distillation column 1 is connected to the inlet of the second distillation column 2, the reflux tank 7 is connected to the top of the second distillation column 2 through the top connecting pipe 13, and the top control valve 14 is installed on the top connecting pipe 13.

[0042] In a specific embodiment, the raw material enters the first distillation column 1 through the feed inlet for first distillation treatment. In the first distillation treatment, the light component (first component) of the raw material is output from the top of the first distillation column 1, the heavy component (second component) of the raw material is output from the bottom of the first distillation column, and the intermediate component of the raw material is output from the outlet of the first distillation column 1 and enters the second distillation column 2 through the feed inlet. The intermediate component undergoes a second distillation treatment in the second distillation column 2. In the second distillation treatment, a portion of the light component of the intermediate component is output from the top of the second distillation column 2 and condensed into a liquid phase by an external cold source. The liquid phase enters the reflux tank 7 for storage. A portion of the liquid phase is output from the reflux tank 7 to obtain a third component, and another portion of the liquid phase is output from the reflux tank 7 and enters the second distillation column 2 through the top of the second distillation column 2 for reflux. The heavy component of the intermediate component is collected from the bottom of the second distillation column 2 to obtain a fourth component. The obtained product is output from the outlet of the second distillation column 2.

[0043] In this invention, the light component output from the top of the second distillation column 2 also enters the reflux tank 7 through the top connecting pipe 13. The amount of light component from the top of the second distillation column 2 entering the reflux tank 7 is regulated by the top control valve 14 installed on the top connecting pipe 13, thereby adjusting the top pressure of the second distillation column 2. Specifically, if the top pressure of the second distillation column 2 is too high, the top control valve 14 is opened, allowing more light component from the top of the second distillation column 2 to enter the reflux tank 7. As the light component is output from the top of the second distillation column 2, the top pressure of the second distillation column 2 gradually decreases. If the top pressure of the second distillation column 2 is too low, the top control valve 14 is closed, allowing the top pressure of the second distillation column 2 to build up, thereby increasing the top pressure of the second distillation column 2. If building up pressure still makes it difficult to achieve the required top pressure, the vapor phase in the reflux tank 7 can be returned to the top of the second distillation column 2, thereby increasing the pressure at the top of the second distillation column 2.

[0044] In the coupled distillation separation system of the present invention, the reflux tank 7 is connected to the top of the second distillation column 2 through the top connecting pipe 13, and the top connecting pipe 13 is also equipped with a top control valve 14, which can be used to control the top pressure of the second distillation column 2 in real time, eliminating the delay in the control process and improving the control sensitivity.

[0045] It is understood that in the coupled distillation separation system of the present invention, the distillation column for material output is the first distillation column 1, and the distillation column for material input is the second distillation column 2. In this invention, the first distillation column 1 and the second distillation column 2 can be any distillation column commonly used in the art; for example, the first distillation column 1 and the second distillation column 2 can each be independently selected from a baffle column or a packed column. The coupled distillation separation system of the present invention is applicable to two-stage or higher coupled distillations; for example, it can be a two-stage coupled distillation, a three-stage coupled distillation, or a four-stage coupled distillation.

[0046] In some embodiments of the present invention, the coupled distillation separation system may further include a pressurization unit, which is connected to the reflux tank 7.

[0047] In a specific implementation, if it is difficult to make the top pressure of the second distillation column 2 meet the operating requirements by pressurizing, the pressurization unit can be used to pressurize the reflux tank 7, and then the top pressure of the second distillation column 2 can be increased through the top connecting pipe 13.

[0048] In some embodiments, the pressurization unit includes a hydrogen pressurization unit and / or a nitrogen pressurization unit.

[0049] When the pressurization unit includes a hydrogen pressurization unit, a hydrogen valve 6 is installed on the pipeline connecting the hydrogen pressurization unit and the reflux tank 7. If the pressure at the top of the second distillation column 2 is too low, the hydrogen valve 6 can be opened to replenish the pressure in the reflux tank 7, thereby increasing the pressure at the top of the second distillation column 2. When the pressurization unit includes a nitrogen pressurization unit, a nitrogen valve 11 is installed on the pipeline connecting the nitrogen pressurization unit and the reflux tank 7. If the pressure at the top of the second distillation column 2 is too low, the nitrogen valve 11 can be opened to replenish the pressure in the reflux tank 7, thereby increasing the pressure at the top of the second distillation column 2. When the pressurization unit includes a nitrogen pressurization unit, nitrogen can also be used to purge and replace the gas in the reflux tank 7.

[0050] In some embodiments of the present invention, the coupled distillation separation system further includes a pressure relief unit, which is connected to the reflux tank 7.

[0051] In a specific implementation, a vent valve 5 is also provided on the pipeline connecting the pressure relief unit and the return tank 7. If the pressure in the return tank 7 is too high, the pressure in the return tank 7 can be reduced through the pressure relief unit to improve the safety of operation.

[0052] In some embodiments of the present invention, the coupled distillation separation system further includes a reboiler 3 disposed in the bottom of the first distillation column 1.

[0053] In this invention, a reboiler 3 can also be installed in the bottom of the first distillation column 1. A portion of the third component output from the bottom of the first distillation column 1 enters the reboiler 3 to provide energy to the bottom of the first distillation column 1.

[0054] In some embodiments of the present invention, the coupled distillation separation system further includes a liquid phase delivery pipe 10;

[0055] The bottom of the first distillation column 1 is connected to the liquid inlet of the reboiler 3, the top of the second distillation column 2 is connected to the gas inlet of the reboiler 3, and the liquid outlet of the reboiler 3 is connected to the reflux tank 7 through the liquid transport pipe 10.

[0056] In a specific implementation, a portion of the third component produced in the bottom of the first distillation column 1 enters the reboiler 3 through the liquid phase inlet, and a portion of the light component produced at the top of the second distillation column 2 enters the reboiler 3 through the gas phase inlet. In the reboiler 3, the third component in the bottom of the first distillation column 1 and the light component produced at the top of the second distillation column 2 undergo heat exchange. On the one hand, the third component in the bottom of the first distillation column 1 condenses the light component produced at the top of the second distillation column 2 into a liquid phase, which is output through the liquid phase outlet of the reboiler 3 and enters the reflux tank 7 through the liquid phase conveying pipe 10. On the other hand, the gas phase at the top of the second distillation column 2 provides energy to the third component in the bottom of the first distillation column 1, thereby providing energy to the bottom of the first distillation column 1.

[0057] In this invention, the above-mentioned configuration enables the condensation and reflux of the gas phase at the top of the second distillation column 2 without the use of condensation equipment or external cold sources. Furthermore, the heat from the gas phase at the top of the second distillation column 2 is used to supplement the heat of the bottom of the first distillation column 1, which helps to save equipment costs and energy consumption.

[0058] This invention does not particularly limit the application system of the coupled distillation separation system. For example, it can be used to separate chlorosilane mixtures. When separating silane mixtures, the crude chlorosilane feedstock containing dichlorosilane, trichlorosilane, silicon tetrachloride, and impurities can enter the first distillation column 1 through the feed inlet for first distillation treatment. After the first distillation treatment, a portion of the high-boiling component (second component) in the crude chlorosilane feedstock is collected from the bottom of the first distillation column 1 and enters the downstream unit. The low-boiling component (first component) in the crude chlorosilane feedstock is collected from the top of the first distillation column 1. The crude trichlorosilane product (intermediate component) in the crude chlorosilane feedstock is collected from the outlet of the first distillation column 1 and enters the second distillation column 2 through the feed inlet. The low-boiling component in the crude trichlorosilane product is collected from the top of the second distillation column 2 and enters the reflux tank. The remaining portion of the high-boiling component (second component) in the crude chlorosilane feedstock is collected from the bottom of the first distillation column 1. The product is collected and enters reboiler 3. The low-boiling component from the second distillation column 2 exchanges heat with the second component from the first distillation column 1 in reboiler 3. In reboiler 3, the light component at the top of the second distillation column 2 vaporizes the second component from the first distillation column 1 and generates heat. The generated heat is output from reboiler 3 and enters the bottom of the first distillation column 1. In reboiler 3, the low-boiling component from the second distillation column 2 is condensed into a liquid phase by the second component to obtain the third component. The third component is output from the liquid phase outlet of reboiler 3 and enters reflux tank 7. Part of the third component is output from reflux tank 7 and enters the downstream unit, while the other part of the third component is used as the top reflux liquid of the second distillation column 2. The high-boiling component (fourth component) in the crude trichlorosilane product is collected from the bottom of the second distillation column 2, and the pure trichlorosilane (product) is collected from the outlet of the second distillation column 2.

[0059] In some embodiments of the present invention, the coupled distillation separation system further includes a gas phase delivery pipe 8;

[0060] The gas phase outlet of reboiler 3 is connected to reflux tank 7 via gas phase delivery pipe 8.

[0061] In this invention, after the top gas phase of the second distillation column 2 and the third component of the bottom of the first distillation column 1 exchange heat in the reboiler 3, the third component of the bottom of the first distillation column 1 will be converted into a gas phase. The gas phase includes a portion of non-condensable gas. The non-condensable gas is output through the gas phase outlet of the reboiler 3 and enters the reflux tank 7 through the gas phase delivery pipe 8.

[0062] If there is too much gas phase or the pressure in the reflux tank 7, the vent valve 5 can be opened to allow the non-condensable gas to be discharged through the vent valve 5.

[0063] Taking the control of the top pressure and temperature of the second distillation column 2 at around 0.52 MPaG as an example, the scheme of the present invention is illustrated as follows: When the top pressure of the second distillation column 2 is higher than 0.54 MPaG, the vent valve 5 is opened to release a portion of the gas, thereby reducing the pressure of the reflux tank 7, and consequently reducing the top pressure of the second distillation column 2, which is connected to the reflux tank 7 through the top connecting pipe 13, until the top pressure of the second distillation column 2 is 0.52 MPaG, at which point the vent valve 5 is closed; When the top pressure of the second distillation column 2 is lower than 0.5 MPaG, the hydrogen valve 6 can be opened to replenish the pressure of the reflux tank 7, thereby increasing the top pressure of the second distillation column 2, which is connected to the reflux tank 7 through the top connecting pipe 13, until the top pressure of the second distillation column 2 is 0.52 MPaG, at which point the hydrogen valve 6 is closed.

[0064] In some embodiments of the present invention, the coupled distillation separation system further includes a gas phase valve 12; the gas phase valve 12 is disposed on the gas phase delivery pipe 8.

[0065] The present invention uses a gas phase valve 12 installed on the gas phase delivery pipe 8 to control the flow of gas phase from the reboiler 3 into the reflux tank 7.

[0066] In the prior art, since the second distillation column 2, reboiler 3, and reflux tank 7 are interconnected, the pressure at the top of the second distillation column 2 is equal to the pressure inside the reflux tank 7, while the liquid phase pressure in the reboiler 3 is less than the pressure inside the reflux tank 7. Therefore, in order to allow the liquid phase in the reboiler 3 to enter the reflux tank 7 and to avoid liquid pockets in the liquid phase delivery pipes 10 of the reboiler 3 and the reflux tank 7, it is usually necessary to install the reboiler 3 and the reflux tank 7 on different floors (for example, the reboiler 3 is installed on the second floor and the reflux tank 7 is installed on the first floor). However, installing the reboiler 3 and the reflux tank 7 on different floors will not only affect the net positive suction head (NPSH) of the pumps on the floor where the reflux tank 7 is located, making pump selection difficult, but will also increase pipeline costs and civil engineering costs.

[0067] In some embodiments of the present invention, the reboiler 3 and the reflux tank 7 can be located on the same plane.

[0068] In this invention, the vapor phase valve 12 can control whether the vapor phase in the reboiler 3 enters the reflux tank 7 (the vapor phase valve 12 can realize whether the reboiler 3 and the reflux tank 7 are connected). When the reflux tank 7 and the reboiler 3 are not connected, the pressure of the reflux tank 7 and the pressure at the top of the second distillation column 2 can be controlled respectively. Therefore, the pressure in the reflux tank 7 can be lower than the pressure at the top of the second distillation column 2. When the reboiler 3 and the reflux tank 7 are located on the same plane, according to the principle of communicating vessels, the pressure difference between the pressure at the top of the second distillation column 2 and the pressure in the reflux tank 7 can be used to force the liquid phase in the reboiler 3 into the reflux tank 7.

[0069] Through the above-described arrangement, the reboiler 3 and the reflux tank 7 can be located on the same plane, saving pipeline costs and civil engineering costs.

[0070] For example, in existing coupled distillation systems, if a reflux tank 7 and a reboiler 3 of the same size are placed on the same plane (two layers), the liquid level in the reflux tank 7 will be 4.5 meters higher than the liquid level in the shell of the reboiler 3 (the base height of the reflux tank on the two layers is 1.1 meters). Therefore, the liquid phase in the shell of the reboiler 3 will have difficulty flowing into the reflux tank 7. To overcome this defect, such as... Figure 1 As shown, existing technologies typically place the reboiler 3 on the second floor and the reflux tank 7 on the first floor (the reflux tank's foundation height on the first floor is 2.4 meters). The second floor is generally 9 meters high, and the liquid level in the inner shell of the reboiler 3 is 3 meters higher than the liquid level in the reflux tank 7, allowing the liquid phase in the reboiler 3 shell to flow into the reflux tank 7. However, the solution of this invention reduces the pressure in the reflux tank 7 by 0.1 MPaG, which is sufficient for the liquid in the reboiler 3 to enter the reflux tank 7 under autopressure. Therefore, the reboiler 3 and the reflux tank 7 can be placed on the same floor, saving approximately 5-10% in structural costs and significantly saving space on the first floor, facilitating personnel operation and equipment maintenance. Furthermore, placing the reboiler 3 and the reflux tank 7 on the same floor increases the inlet pressure of the reflux pump, increasing the pump's net positive suction head (NPSH), which not only saves on costs but also makes the pump's operation safer and more stable.

[0071] In some embodiments, the coupling and separation system of the present invention may further include a pressure detection unit 9, which is disposed at the top of the second distillation column 2. The vent valve 5, hydrogen valve 6, nitrogen valve 11, gas phase valve 12, and column top control valve 14 are on / off valves, which can be manually adjusted to open and close the vent valve 5, hydrogen valve 6, nitrogen valve 11, gas phase valve 12, and column top control valve 14 according to the data of the pressure detection unit 9.

[0072] In some embodiments, the coupling and separation system of the present invention may further include a control unit. The vent valve 5, hydrogen valve 6, nitrogen valve 11, gas phase valve 12, tower top control valve 14 and pressure detection unit 9 may be electrically connected to the control unit. The control unit adjusts the opening and closing of the vent valve 5, hydrogen valve 6, nitrogen valve 11, gas phase valve 12 and tower top control valve 14 in real time according to the data fed back by the pressure detection unit 9.

[0073] In some embodiments, the vent valve 5, hydrogen valve 6, nitrogen valve 11, top control valve 14, and pressure detection unit 9 can be electrically connected to the control unit, and the gas phase valve 12 is a switching valve. The opening and closing of the vent valve 5, hydrogen valve 6, nitrogen valve 11, and top control valve 14 can be controlled by the control unit, and the opening and closing of the gas phase valve 12 can be manually adjusted.

[0074] A second aspect of the present invention provides a coupled distillation separation method, wherein the coupled distillation separation system described above is used.

[0075] The coupled distillation separation method of the present invention, because it uses the above-mentioned coupled distillation separation system, can control the top pressure of the second distillation column 2 in real time, and is simple to operate and suitable for widespread application.

[0076] The present invention will be further described below with reference to specific embodiments.

[0077] Example 1

[0078] like Figure 2 As shown, the coupling separation system in this embodiment includes:

[0079] First distillation column 1, second distillation column 2, reflux tank 7, top connecting pipe 13, top control valve 14, pressurization unit, depressurization unit, reboiler 3, liquid phase delivery pipe 10, gas phase delivery pipe 8, and gas phase valve 12.

[0080] The outlet of the first distillation column 1 is connected to the inlet of the second distillation column 2, the reflux tank 7 is connected to the top of the second distillation column 2 through the top connecting pipe 13, and the top control valve 14 is installed on the top connecting pipe 13.

[0081] The pressurization unit is connected to the reflux tank 7. The pressurization unit includes a hydrogen pressurization unit and a nitrogen pressurization unit. A hydrogen valve 6 is installed on the connecting pipeline between the hydrogen pressurization unit and the reflux tank 7, and a nitrogen valve 11 is installed on the connecting pipeline between the nitrogen pressurization unit and the reflux tank 7.

[0082] The pressure relief unit is connected to the return tank 7, and an air vent valve 5 is installed on the connecting pipeline between the pressure relief unit and the return tank 7.

[0083] The bottom of the first distillation column 1 is connected to the liquid inlet of the reboiler 3, the top of the second distillation column 2 is connected to the gas inlet of the reboiler 3, the liquid outlet of the reboiler 3 is connected to the reflux tank 7 through the liquid phase delivery pipe 10, the gas outlet of the reboiler 3 is connected to the reflux tank 7 through the gas phase delivery pipe 8, the gas phase valve 12 is installed on the gas phase delivery pipe 8, and the reboiler 3 and the reflux tank 7 are located on the same plane.

[0084] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A coupled distillation separation system, characterized in that, This includes a first distillation column, a second distillation column, a reflux tank, a top connecting pipe, and a top control valve; The outlet of the first distillation column is connected to the inlet of the second distillation column, the reflux tank is connected to the top of the second distillation column through the top connecting pipe, and the top control valve is located on the top connecting pipe. It also includes a reboiler disposed in the bottom of the first distillation column; It also includes a liquid phase delivery pipe; the bottom of the first distillation column is connected to the liquid phase inlet of the reboiler, the top of the second distillation column is connected to the gas phase inlet of the reboiler, and the liquid phase outlet of the reboiler is connected to the reflux tank through the liquid phase delivery pipe; It also includes a vapor phase delivery pipe; the vapor phase outlet of the reboiler is connected to the reflux tank through the vapor phase delivery pipe; It also includes a gas phase valve; the gas phase valve is disposed on the gas phase delivery pipe; The reboiler and the reflux tank are located on the same plane.

2. The coupled distillation separation system according to claim 1, characterized in that, It also includes a pressurization unit, which is connected to the reflux tank.

3. The coupled distillation separation system according to claim 2, characterized in that, The pressurization unit includes a hydrogen pressurization unit and / or a nitrogen pressurization unit.

4. The coupled distillation separation system according to any one of claims 1-3, characterized in that, It also includes a pressure relief unit, which is connected to the reflux tank.

5. A coupled distillation separation method, characterized in that, The coupled distillation separation system according to any one of claims 1-4 is used.

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