An extractive distillation device

Abstract

The present invention provides an extractive distillation device, belonging to the technical field of distillation equipment. The extractive distillation device includes an extractive distillation column and an extractant recovery column. A reboiler is connected to the bottom discharge port of the extractant recovery column. The reboiler is connected to the extractive distillation column through a shunt tank. Two heat-conducting partitions are fixedly connected inside the shunt tank. The two heat-conducting partitions can divide the inside of the shunt tank into a diversion chamber, a buffer chamber, and a heating chamber from bottom to top in sequence. Through the setting of the shunt tank, on the one hand, it avoids directly heating the bottom product of the extractive distillation column entering the heating chamber, and on the other hand, it can heat the product entering the buffer chamber, avoiding the top product from becoming liquid due to heat loss during transportation. The product entering the buffer chamber can be used to heat the extractive distillation column. Furthermore, the heating of the two columns can be achieved by one reboiler, reducing energy consumption and cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of rectification equipment, and particularly relates to an extractive distillation device. Background Art

[0002] Extractive distillation, also known as extractive rectification, is a technique for separating the components of a mixture based on the difference in volatility of each component by using a selective solvent. Its principle is to introduce a third component into the feed liquid to adjust the relative volatility between the components, thereby achieving effective separation.

[0003] Chinese Patent with application number CN202411769747.3 discloses a method for separating the azeotrope of 1-fluoro-1,1-dichloroethane and 1,1,1,3,3-pentafluorobutane by extractive distillation. In this method for separating the azeotrope of 1-fluoro-1,1-dichloroethane and 1,1,1,3,3-pentafluorobutane by extractive distillation, an extractant is added to the azeotrope of 1-fluoro-1,1-dichloroethane and 1,1,1,3,3-pentafluorobutane, and the extractant is one or more of n-pentanol and n-heptanol. This invention adopts batch extractive distillation or continuous extractive distillation operation, with the advantages of simple and efficient separation process, high product purity, low loss rate of the extractant, recyclability of the extractant, and avoidance of environmental pollution.

[0004] However, in the process of continuous extractive distillation, an extractive distillation column and an extractant recovery column need to be used in combination. Usually, two reboilers need to be connected to meet the extraction requirements. Using two reboilers results in high energy consumption and large costs. Moreover, when separating the azeotrope of HCFC-141b (dichlorofluoroethane) and HFC-365mfc (1,1,1,3,3-pentafluorobutane) in the extractive distillation column by the extractant, it may be affected by factors such as liquid leakage or insufficient gas-liquid mass transfer, resulting in partial HCFC-141b being doped in the bottom product of the extractive distillation column. As a result, when separating HFC-365mfc and the extractant from the mixture entering the extractant recovery column, there is HCFC-141b, which affects the separation quality.

[0005] Therefore, in order to solve the above problems, an extractive distillation device is needed. Summary of the Invention

[0006] The object of the present invention is to provide an extractive distillation device, aiming to solve the problems in the prior art of extractive distillation. In the prior art, multiple towers such as an extractive distillation tower and an extractant recovery tower are required to be used in cooperation. Usually, multiple reboilers need to be connected to meet the extraction requirements. Using multiple reboilers results in high energy consumption and large costs. Moreover, when separating the azeotrope of HCFC-141b and HFC-365mfc in the extractive distillation tower through an extractant, it may be affected by factors such as liquid leakage or insufficient mass transfer between gas and liquid phases, resulting in partial HCFC-141b being doped in the bottom product of the extractive distillation tower. As a result, in the mixture entering the extractant recovery tower, there is HCFC-141b when separating HFC-365mfc and the extractant, which affects the separation quality.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] An extractive distillation device, comprising an extractive distillation tower and an extractant recovery tower:

[0009] The bottom discharge port of the extractant recovery tower is connected to a reboiler, and the reboiler is connected to the extractive distillation tower through a shunt tank. Both the bottom product and the top product of the extractant recovery tower can enter the interior of the shunt tank. Among them, the bottom product of the extractant recovery tower can heat the top product of the extractant recovery tower inside the shunt tank after being heated by the reboiler, and the top product of the extractant recovery tower inside the shunt tank can enter the interior of the extractive distillation tower and can heat the substances inside the extractive distillation tower;

[0010] Two heat conduction partitions are fixedly connected inside the shunt tank. The two heat conduction partitions can divide the interior of the shunt tank into a diversion chamber, a buffer chamber, and a heating chamber from bottom to top in sequence. A first feed pipe communicating with the diversion chamber is provided at the bottom of the shunt tank, a first discharge pipe communicating with the diversion chamber is provided outside the shunt tank, a second discharge pipe communicating with the buffer chamber is provided at the top of the shunt tank, a second feed pipe communicating with the buffer chamber is provided outside the shunt tank, a third feed pipe and a third discharge pipe communicating with the heating chamber are further provided outside the shunt tank, and at least two diversion pipes communicating with the second discharge pipe and the heating chamber are provided at the top of the shunt tank.

[0011] Preferably, the discharge port of the reboiler is connected to a first reflux tank and is in communication with the first feed pipe. The first discharge pipe is in communication with the bottom reflux port of the extractant recovery column. The bottom product of the extractant recovery column can enter the interior of the reboiler. After the product entering the interior of the reboiler is heated, a part of it enters the interior of the diversion chamber through the first feed pipe, and the other part enters the interior of the first reflux tank. The first reflux tank is connected to the extractant feed port of the extractive distillation column through a reflux pump. The product entering the interior of the first reflux tank can enter the interior of the extractive distillation column through the reflux pump. The product entering the interior of the diversion chamber can enter the interior of the extractant recovery column through the first discharge pipe.

[0012] Preferably, the bottom discharge port of the extractive distillation column is in communication with a third feed pipe. The third discharge pipe is in communication with the feed port of the extractant recovery column. The bottom product of the extractive distillation column can enter the interior of the heating chamber through the third feed pipe. The product entering the interior of the heating chamber can enter the interior of the extractant recovery column through the third discharge pipe.

[0013] Preferably, the top of the extractant recovery column is in communication with the second feed pipe. The second discharge pipe is in communication with the bottom reflux port of the extractive distillation column through a first condenser. The top product of the extractant recovery column can enter the interior of the buffer chamber through the second feed pipe. The product entering the interior of the buffer chamber can enter the interior of the extractive distillation column through the second discharge pipe and the first condenser.

[0014] Preferably, the connection position of the second feed pipe to the extractant recovery column is higher than the connection position of the third discharge pipe to the extractant recovery column. Each of the diversion pipes is inclined. The connection position of the diversion pipe to the second discharge pipe is higher than the connection position of the diversion pipe to the heating chamber. The connection positions of the third feed pipe and the third discharge pipe to the heating chamber are both lower than the connection position of the diversion pipe to the heating chamber.

[0015] Preferably, the top discharge port of the extractive distillation column is connected to a second condenser. The discharge port of the second condenser is connected to a second reflux tank. The discharge port of the second reflux tank is connected to a first collection tank and is in communication with the top reflux port of the extractive distillation column.

[0016] Preferably, the top product of the extractive distillation column can enter the interior of the second reflux tank after being condensed by the second condenser. A part of the product entering the interior of the second reflux tank can enter the interior of the first collection tank, and the other part can enter the interior of the extractive distillation column.

[0017] Preferably, the top discharge port of the extractant recovery tower is connected to a third condenser, the discharge port of the third condenser is connected to a third reflux drum, the discharge port of the third reflux drum is connected to a second collection tank, and is communicated with the top reflux port of the extractant recovery tower.

[0018] Preferably, a part of the top product of the extractant recovery tower can enter the interior of the second feed pipe, and another part can enter the interior of the third reflux drum after being condensed by the third condenser. A part of the product entering the interior of the third reflux drum can enter the interior of the second collection tank, and another part can enter the interior of the extractant recovery tower.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. Through the setting of the shunt tank in the present invention, after the reboiler heats the extractant at the bottom of the extractant recovery tower, a part of the extractant can enter the interior of the diversion chamber through the first feed pipe. The extractant entering the interior of the diversion chamber will preferentially heat the substances in the buffer chamber through the heat conduction partition, and then the substances in the buffer chamber will heat the bottom product of the extractive distillation tower entering the heating chamber through another heat conduction partition. The purpose is, on the one hand, to avoid directly heating the bottom product of the extractive distillation tower entering the heating chamber, prevent a large amount of HFC-365mfc gas from being separated out due to the high temperature of n-pentanol and HFC-365mfc entering the heating chamber, and avoid the low content of HFC-365mfc in the substances entering the extractant recovery tower, which affects the separation efficiency. On the other hand, it can heat the top product of the extractant recovery tower entering the buffer chamber, avoid the top product from changing from gas to liquid due to heat loss during transportation, which is convenient for subsequent use. Moreover, the product entering the interior of the buffer chamber can enter the interior of the extractive distillation tower through the second discharge pipe and the first condenser, which can heat the extractive distillation tower, ensure the reaction temperature inside the extractive distillation tower, and can realize the heating of two towers through one reboiler, reducing the energy consumption and cost.

[0021] 2. Through the arrangement of the diversion pipe, a part of the overhead product of the extractant recovery tower can enter the interior of the second feed pipe, and the bottom product that enters the interior of the second feed pipe can enter the interior of the buffer chamber. Since the temperature inside the buffer chamber is higher than that inside the heating chamber, and the internal pressure of the buffer chamber is greater than that inside the heating chamber, the overhead substances that remain in the gas phase inside the buffer chamber enter the extractive distillation tower at a relatively high flow rate from the second discharge pipe, resulting in a weakened pressure at the connection between the second discharge pipe and the diversion pipe. Moreover, due to the existence of a certain temperature and pressure inside the heating chamber, the overhead substances of the extractive distillation tower that enter the heating chamber and are volatilized by heat enter the interior of the second discharge pipe in a gaseous state through the diversion pipe, and coexist with the overhead product of the extractant recovery tower, and then re-enter the interior of the extractive distillation tower for separation. By virtue of the coexistence of the overhead product of the extractant recovery tower and the overhead substances of the extractive distillation tower, the content of the overhead substances of the extractive distillation tower in the substances entering the extractant recovery tower can be reduced, and the separation quality of the extractant recovery tower can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0023] Figure 1 is a schematic structural diagram of the extractive distillation device of the present invention;

[0024] Figure 2 is a schematic structural diagram of the shunt tank of the present invention;

[0025] Figure 3 is a cross-sectional structural view of the shunt tank of the present invention.

[0026] In the figures: 1, extractive distillation tower; 11, first condenser; 12, second condenser; 13, second reflux tank; 14, first collection tank; 2, extractant recovery tower; 21, reboiler; 22, first reflux tank; 23, reflux pump; 24, third condenser; 25, third reflux tank; 26, second collection tank; 3, shunt tank; 31, heat conduction partition; 32, diversion chamber; 33, buffer chamber; 34, heating chamber; 35, first feed pipe; 36, first discharge pipe; 37, second discharge pipe; 38, second feed pipe; 39, third feed pipe; 310, third discharge pipe; 311, diversion pipe. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment 1

[0028] In the existing extractive distillation, multiple towers such as an extractive distillation column and an extractant recovery column are often required to be used in cooperation. Usually, multiple reboilers need to be connected to meet the extraction requirements. The purpose of using multiple reboilers is to ensure the temperature requirements of different reaction towers. However, the overall energy consumption of multiple reboilers is relatively high, and the cost is relatively large.

[0029] Please refer to Figures 1 to 3 , the present invention provides the following technical solutions: An extractive distillation device includes an extractive distillation column 1 and an extractant recovery column 2:

[0030] A reboiler 21 is connected to the bottom discharge port of the extractant recovery column 2. The reboiler 21 is connected to the extractive distillation column 1 through a shunt tank 3. Both the bottom product and the top product of the extractant recovery column 2 can enter the interior of the shunt tank 3. Among them, the bottom product of the extractant recovery column 2 can heat the top product of the extractant recovery column 2 inside the shunt tank 3 after being heated by the reboiler 21, and the top product of the extractant recovery column 2 inside the shunt tank 3 can heat the material entering the interior of the extractive distillation column 1.

[0031] Two heat-conducting partition plates 31 are fixedly connected inside the shunt tank 3. The two heat-conducting partition plates 31 can divide the interior of the shunt tank 3 into a diversion chamber 32, a buffer chamber 33, and a heating chamber 34 from bottom to top in sequence. A first feed pipe 35 communicating with the diversion chamber 32 is provided at the bottom of the shunt tank 3. A first discharge pipe 36 communicating with the diversion chamber 32 is provided outside the shunt tank 3. A second discharge pipe 37 communicating with the buffer chamber 33 is provided at the top of the shunt tank 3. A second feed pipe 38 communicating with the buffer chamber 33 is provided outside the shunt tank 3. A third feed pipe 39 and a third discharge pipe 310 communicating with the heating chamber 34 are further provided outside the shunt tank 3. At least two diversion pipes 311 communicating with the second discharge pipe 37 and the heating chamber 34 are provided at the top of the shunt tank 3.

[0032] The bottom discharge port of the extractant recovery column 2 is connected to a reboiler 21. The discharge port of the reboiler 21 is connected to a first reflux tank 22. The discharge port of the reboiler 21 is also connected to a first feed pipe 35. A first discharge pipe 36 is connected to the bottom reflux port of the extractant recovery column 2. The bottom product of the extractant recovery column 2 can enter the interior of the reboiler 21. After the product entering the interior of the reboiler 21 is heated, part of it enters the interior of the diversion chamber 32 through the first feed pipe 35, and the other part enters the interior of the first reflux tank 22. The first reflux tank 22 is connected to the extractant feed port of the extractive distillation column 1 through a reflux pump 23. The product entering the interior of the first reflux tank 22 can enter the interior of the extractive distillation column 1 through the reflux pump 23. The product entering the interior of the diversion chamber 32 can enter the interior of the extractant recovery column 2 through the first discharge pipe 36.

[0033] The bottom discharge port of the extractive distillation column 1 is connected to a third feed pipe 39. A third discharge pipe 310 is connected to the feed port of the extractant recovery column 2. The bottom product of the extractive distillation column 1 can enter the interior of the heating chamber 34 through the third feed pipe 39. The product entering the interior of the heating chamber 34 can enter the interior of the extractant recovery column 2 through the third discharge pipe 310.

[0034] The top of the extractant recovery column 2 is connected to a second feed pipe 38. A second discharge pipe 37 is connected to the bottom reflux port of the extractive distillation column 1 through a first condenser 11. The top product of the extractant recovery column 2 can enter the interior of the buffer chamber 33 through the second feed pipe 38. The product entering the interior of the buffer chamber 33 can enter the interior of the extractive distillation column 1 through the second discharge pipe 37 and the first condenser 11.

[0035] The purpose of setting the first condenser 11 is to prevent the temperature of the product entering the interior of the extractive distillation column 1 from the buffer chamber 33 from being higher than the internal reaction temperature of the extractive distillation column 1.

[0036] The top discharge port of the extractive distillation column 1 is connected to a second condenser 12. The discharge port of the second condenser 12 is connected to a second reflux tank 13. The discharge port of the second reflux tank 13 is connected to a first collection tank 14. The discharge port of the second reflux tank 13 is also connected to the top reflux port of the extractive distillation column 1.

[0037] The top product of the extractive distillation column 1 can enter the interior of the second reflux tank 13 after being condensed by the second condenser 12. Part of the product entering the interior of the second reflux tank 13 can enter the interior of the first collection tank 14, and the other part can enter the interior of the extractive distillation column 1.

[0038] Generally, the overhead product of the extractive distillation column 1 is a gas, which is condensed into a liquid by the second condenser 12 and enters the interior of the second reflux drum 13. Part of it enters the first collection tank 14 for collection, and the other part refluxes into the interior of the extractive distillation column 1 to ensure the liquid level height inside the extractive distillation column 1 and maintain the pressure inside the column.

[0039] The overhead discharge port of the extractant recovery column 2 is connected to a third condenser 24. The discharge port of the third condenser 24 is connected to a third reflux drum 25. The discharge port of the third reflux drum 25 is connected to a second collection tank 26, and the discharge port of the third reflux drum 25 is also connected to the overhead reflux port of the extractant recovery column 2.

[0040] Part of the overhead product of the extractant recovery column 2 can enter the interior of the second feed pipe 38, and the other part can enter the interior of the third reflux drum 25 after being condensed by the third condenser 24. Part of the product that enters the interior of the third reflux drum 25 can enter the interior of the second collection tank 26, and the other part can enter the interior of the extractant recovery column 2.

[0041] Generally, the overhead product of the extractant recovery column 2 is a gas. After being condensed into a liquid by the third condenser 24, part of it enters the second collection tank 26 for collection, and the other part refluxes into the interior of the extractant recovery column 2 to ensure the liquid level height inside the extractant recovery column 2 and maintain the pressure inside the column.

[0042] The raw material is added through the feed port of the extractive distillation column 1, and the extractant is added through the extractant feed port of the extractive distillation column 1. The prior art will not be elaborated here.

[0043] For example, when separating the azeotrope of HCFC-141b and HFC-365mfc, by selecting n-pentanol as the extractant, in the process of separating the azeotrope of HCFC-141b and HFC-365mfc through n-pentanol in the extractive distillation column 1, the product at the bottom of the extractive distillation column 1 is mainly a mixture of n-pentanol and HFC-365mfc, and the product at the top of the extractive distillation column 1 is mainly HCFC-141b. The boiling point of HFC-365mfc is about 40°C, the boiling point of HCFC-141b is about 32°C, and the boiling point of the extractant n-pentanol is about 138°C. Due to the strong interaction between n-pentanol and HFC-365mfc, during separation, n-pentanol can be mixed with HFC-365mfc to increase the boiling point and reduce the volatility of HFC-365mfc, enabling the separation of HCFC-141b. The mixture of n-pentanol and HFC-365mfc at the bottom of the extractive distillation column 1 enters the interior of the extractant recovery column 2. During the separation process, the product at the bottom of the extractant recovery column 2 is mainly the extractant n-pentanol, and the product at the top of the extractant recovery column 2 is mainly HFC-365mfc. During the separation process, the overall temperature of the extractant recovery column 2 is higher than that of the extractive distillation column 1, aiming to ensure that HFC-365mfc can be volatilized and separated when the extractant recovery column 2 is heated. The prior art will not be elaborated here.

[0044] It should be noted that since the temperature of the bottom product of the extractant recovery column 2 entering the internal heating of the reboiler 21 is higher than the overall temperature of the extractive distillation column 1, after the reboiler 21 heats the extractant of the bottom product of the extractant recovery column 2, a part of the extractant can enter the inside of the diversion cavity 32 through the first feed pipe 35, and another part of the extractant enters the inside of the first reflux tank 22. Among them, the extractant entering the inside of the diversion cavity 32 will preferentially heat the substances inside the buffer cavity 33 through the heat conduction partition 31, and then the substances inside the buffer cavity 33 will heat the bottom product of the extractive distillation column 1 entering the heating cavity 34 through another heat conduction partition 31. The purpose of this is that, on the one hand, since the temperature of the extractant after being heated by the reboiler 21 is higher than the temperature of the extractive distillation column 1, directly heating the bottom product of the extractive distillation column 1 entering the heating cavity 34 is avoided, preventing a large amount of HFC-365mfc gas from being separated due to the relatively high temperature of n-pentanol and HFC-365mfc entering the heating cavity 34, and avoiding the low content of HFC-365mfc in the substances entering the extractant recovery column 2 from affecting the separation efficiency. On the other hand, the extractant entering the inside of the diversion cavity 32 can heat the substances inside the buffer cavity 33 through the heat conduction partition 31, and can heat the HFC-365mfc, the top product of the extractant recovery column 2, entering the buffer cavity 33, avoiding the HFC-365mfc product from changing from gas to liquid due to heat loss during transportation. Moreover, the HFC-365mfc entering the buffer cavity 33 can enter the inside of the extractive distillation column 1 through the second discharge pipe 37 and the first condenser 11, and can heat the extractive distillation column 1 to ensure the reaction temperature inside the extractive distillation column 1. Thus, the heating of two towers can be achieved by one reboiler 21, reducing energy consumption and cost.

[0045] Through the setting of the shunt tank 3, after the reboiler 21 heats the bottom product extractant of the extractant recovery tower 2, a part of the extractant can enter the inside of the diversion cavity 32 through the first feed pipe 35. The extractant entering the inside of the diversion cavity 32 will preferentially heat the substances inside the buffer cavity 33 through the heat conduction partition 31. Subsequently, the substances inside the buffer cavity 33 will heat the bottom product of the extractive distillation column 1 entering the heating cavity 34 through another heat conduction partition 31. The purpose is, on the one hand, to avoid directly heating the bottom product of the extractive distillation column 1 entering the heating cavity 34, preventing more HFC-365mfc gas from being separated from the n-pentanol and HFC-365mfc entering the heating cavity 34 due to the high temperature, and avoiding the low content of HFC-365mfc in the substances entering the extractant recovery tower 2 from affecting the separation efficiency. On the other hand, it can heat the top product of the extractant recovery tower 2 entering the buffer cavity 33, avoiding the top product of the extractant recovery tower 2 from changing from gas to liquid due to heat loss during transportation, facilitating subsequent use. Moreover, the product entering the buffer cavity 33 can enter the inside of the extractive distillation column 1 through the second discharge pipe 37 and the first condenser 11, and can heat the extractive distillation column 1 to ensure the reaction temperature inside the extractive distillation column 1. It can realize the heating of two towers through one reboiler 21, reducing the energy consumption and the cost. Example Two

[0046] When the extractive distillation column separates the azeotrope of HCFC-141b and HFC-365mfc through the extractant, it may be affected by factors such as weeping phenomenon or insufficient gas-liquid mass transfer, resulting in part of HCFC-141b being doped in the bottom product of the extractive distillation column, and there is HCFC-141b in the mixed substances entering the extractant recovery tower when separating HFC-365mfc and the extractant, affecting the separation quality.

[0047] The weeping phenomenon refers to that the liquid fails to form a normal liquid layer on the tray, but directly leaks into the lower layer through the holes on the tray (such as sieve holes, valve float gaps, etc.) or the channel of the packing layer, rather than flowing along the designed path. This will destroy the ideal contact state of the gas-liquid two-phase. The reasons are: the gas phase load is too low, resulting in insufficient rising vapor volume and unable to effectively hold the liquid on the tray, causing the liquid to leak from the holes; or the liquid phase load is too large, resulting in too thick a liquid layer or too high a flow rate on the tray, exceeding the design requirements, overcoming the gas holding force, and the liquid is forced to leak from the holes.

[0048] Please refer to Figures 1 to 3 , the connection position of the second feed pipe 38 with the extractant recovery tower 2 is higher than the connection position of the third discharge pipe 310 with the extractant recovery tower 2;

[0049] The purpose is to ensure that the substance entering the interior of the second feed pipe 38 is the overhead product HFC-365mfc of the top of the extractant recovery column 2.

[0050] As Figure 3 shown, each diversion pipe 311 is inclined, and the connection position of the diversion pipe 311 to the second discharge pipe 37 is higher than the connection position of the diversion pipe 311 to the heating chamber 34;

[0051] The purpose of such a setting is to avoid the flow direction of the substance inside the buffer chamber 33 corresponding to the connection port of the diversion pipe 311 and the second discharge pipe 37 when the substance inside the buffer chamber 33 enters the interior of the extractive distillation column 1 through the second discharge pipe 37, and prevent the substance inside the buffer chamber 33 from entering the interior of the heating chamber 34.

[0052] The connection positions of the third feed pipe 39 and the third discharge pipe 310 to the heating chamber 34 are lower than the connection position of the diversion pipe 311 to the heating chamber 34, and the purpose is to prevent the liquid inside the heating chamber 34 from entering the interior of the diversion pipe 311;

[0053] Since the extractant is heated by the reboiler 21, its temperature is higher than that of the extractive distillation column 1. The extractant inside the diversion chamber 32 will preferentially heat the substance inside the buffer chamber 33 through the heat conduction partition 31. Subsequently, the substance inside the buffer chamber 33 will heat the bottom product of the extractive distillation column 1 entering the interior of the heating chamber 34 through another heat conduction partition 31, making the temperature inside the buffer chamber 33 higher than the temperature inside the heating chamber 34. Temperature is proportional to pressure, resulting in the internal pressure of the buffer chamber 33 being greater than the internal pressure of the heating chamber 34.

[0054] The extractant inside the diversion chamber 32 will preferentially heat the substance inside the buffer chamber 33 through the heat conduction partition 31. In order to keep HFC-365mfc in a gaseous state, it is convenient to maintain stability when subsequently mixed and coexisted with gaseous HCFC-141b and prevent the diffusion of HCFC-141b.

[0055] It should be noted that part of the overhead product HFC-365mfc of the extractant recovery column 2 can enter the inside of the second feed pipe 38, and the other part of HFC-365mfc can enter the inside of the third reflux drum 25 after being condensed by the third condenser 24. The HFC-365mfc entering the inside of the second feed pipe 38 can enter the buffer chamber 33. Since the temperature inside the buffer chamber 33 is higher than the temperature inside the heating chamber 34, the internal pressure of the buffer chamber 33 is greater than the internal pressure of the heating chamber 34. As the pressure is proportional to the flow rate, the HFC-365mfc that remains in the gaseous phase inside the buffer chamber 33 enters the extractive distillation column 1 at a relatively high flow rate from the second discharge pipe 37. Due to the relatively high flow rate, the pressure at the connection between the second discharge pipe 37 and the diversion pipe 311 becomes weak. And because there is a certain temperature and pressure inside the heating chamber 34, the gas generated by the volatilization of the substance entering the heating chamber 34 can enter the inside of the second discharge pipe 37 through the diversion pipe 311.

[0056] By selecting heat-conducting partitions 31 with different heat conductivities and setting the height of the buffer chamber 33 to adjust the heating degree of the buffer chamber 33 to the heating chamber 34, the prior art will not be elaborated here. The internal temperature of the heating chamber 34 should meet the reaction temperature inside the extractive distillation column 1 and be lower than the reaction temperature inside the extractant recovery column 2. The purpose is to ensure that after the substance inside the heating chamber 34 is heated, HCFC-141b can be preferentially volatilized. Since HCFC-141b and HFC-365mfc have strong coexistence without the interference of the extractant, when the HFC-365mfc entering the inside of the second discharge pipe 37 flows through the connection between the second discharge pipe 37 and the diversion pipe 311, if HCFC-141b is volatilized inside the heating chamber 34, the HCFC-141b volatilized inside the heating chamber 34 can be carried back into the inside of the extractive distillation column 1 for separation through the coexistence of HCFC-141b and HFC-365mfc. Thus, the content of HCFC-141b in the substance entering the extractant recovery column 2 can be effectively reduced, and the separation quality can be improved.

[0057] With the arrangement of the diversion pipe 311 in the present invention, a part of the overhead product of the extractant recovery tower 2 can enter the interior of the second feed pipe 38 and then enter the interior of the buffer chamber 33. Since the temperature inside the buffer chamber 33 is higher than that inside the heating chamber 34, the internal pressure of the buffer chamber 33 is greater than that inside the heating chamber 34. As a result, the overhead substances that remain in the gas phase inside the buffer chamber 33 enter the interior of the extractive distillation column 1 from the second discharge pipe 37 at a relatively high flow rate, causing the pressure at the connection between the second discharge pipe 37 and the diversion pipe 311 to weaken. Moreover, due to the existence of a certain temperature and pressure inside the heating chamber 34, the overhead substances of the extractive distillation column 1 that enter the heating chamber 34 and are volatilized by heat enter the interior of the second discharge pipe 37 through the diversion pipe 311 in a gaseous state, mix and coexist with the overhead product of the extractant recovery tower 2, and then re-enter the interior of the extractive distillation column 1 for separation. By virtue of the coexistence of the overhead product of the extractant recovery tower 2 and the overhead substances of the extractive distillation column 1, the content of the overhead substances of the extractive distillation column 1 in the substances entering the extractant recovery tower 2 can be reduced, and the separation quality of the extractant recovery tower 2 can be improved.

[0058] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An extractive distillation device, comprising an extractive distillation tower (1) and an extractant recovery tower (2), characterized in that: The bottom discharge port of the extractant recovery tower (2) is connected to a reboiler (21), and the reboiler (21) is connected to the extractive distillation tower (1) via a splitter tank (3). Both the bottom product and the top product of the extractant recovery tower (2) can enter the splitter tank (3), wherein the bottom product of the extractant recovery tower (2) can heat the top product of the extractant recovery tower (2) in the splitter tank (3) after being heated by the reboiler (21), and the top product of the extractant recovery tower (2) in the splitter tank (3) can enter the extractive distillation tower (1) to heat the substances in the extractive distillation tower (1); Two heat-conducting baffles (31) are fixedly connected to the interior of the diverter tank (3), and the two heat-conducting baffles (31) can divide the interior of the diverter tank (3) into a diversion chamber (32), a buffer chamber (33) and a heating chamber (34) from bottom to top. A first feed pipe (35) connected to the diversion chamber (32) is provided at the bottom of the diverter tank (3), and a first discharge pipe (36) connected to the diversion chamber (32) is provided on the outside of the diverter tank (3). A second discharge pipe (37) connected to the buffer chamber (33) is provided on the top of the diverter tank (3); a second feed pipe (38) connected to the buffer chamber (33) is provided on the outside of the diverter tank (3); a third feed pipe (39) and a third discharge pipe (310) connected to the heating chamber (34) are also provided on the outside of the diverter tank (3); and at least two guide pipes (311) connected to the second discharge pipe (37) and the heating chamber (34) are provided on the top of the diverter tank (3); Each of the flow guide tubes (311) is arranged at an angle; a connection position between the flow guide tube (311) and the second discharge tube (37) is higher than a connection position between the flow guide tube (311) and the heating chamber (34); and a connection position between the third feed tube (39) and the third discharge tube (310) and the heating chamber (34) is lower than a connection position between the flow guide tube (311) and the heating chamber (34).

2. The extractive distillation device according to claim 1, characterized in that: The discharge port of the reboiler (21) is connected to a first reflux tank (22) and is in communication with a first feed pipe (35). The first discharge pipe (36) is in communication with a bottom reflux port of the extractant recovery tower (2). The bottom product of the extractant recovery tower (2) can enter the interior of the reboiler (21). After being heated, part of the product entering the interior of the reboiler (21) enters the interior of the guide chamber (32) through the first feed pipe (35), and the other part enters the interior of the first reflux tank (22). The first reflux tank (22) is connected to the extractant feed port of the extractive distillation tower (1) through a reflux pump (23). The product entering the interior of the first reflux tank (22) can enter the interior of the extractive distillation tower (1) through the reflux pump (23), and the product entering the interior of the guide chamber (32) can enter the interior of the extractive distillation tower (2) through the first discharge pipe (36).

3. The extractive distillation device according to claim 2, characterized in that: The bottom discharge port of the extractive distillation tower (1) is connected to the third feed pipe (39), and the third discharge pipe (310) is connected to the feed port of the extractant recovery tower (2). The bottom product of the extractive distillation tower (1) can enter the interior of the heating chamber (34) through the third feed pipe (39), and the product entering the interior of the heating chamber (34) can enter the interior of the extractant recovery tower (2) through the third discharge pipe (310).

4. The extractive distillation device according to claim 3, characterized in that: The top of the extractant recovery tower (2) is connected to the second feed pipe (38), and the second discharge pipe (37) is connected to the bottom reflux port of the extractive distillation tower (1) through the first condenser (11). The top product of the extractant recovery tower (2) can enter the interior of the buffer chamber (33) through the second feed pipe (38), and the product entering the interior of the buffer chamber (33) can enter the interior of the extractive distillation tower (1) through the second discharge pipe (37) and the first condenser (11).

5. The extractive distillation device according to claim 4, characterized in that: The connection position between the second feed pipe (38) and the extractant recovery tower (2) is higher than the connection position between the third discharge pipe (310) and the extractant recovery tower (2).

6. The extractive distillation device according to claim 5, characterized in that: The top discharge port of the extractive distillation tower (1) is connected to a second condenser (12), the discharge port of the second condenser (12) is connected to a second reflux tank (13), the discharge port of the second reflux tank (13) is connected to a first collecting tank (14), and is in communication with the top reflux port of the extractive distillation tower (1).

7. The extractive distillation device according to claim 6, characterized in that: The top product of the extractive distillation tower (1) can enter the interior of the second reflux tank (13) after being condensed by the second condenser (12); part of the product entering the interior of the second reflux tank (13) can enter the interior of the first collecting tank (14), and the other part can enter the interior of the extractive distillation tower (1).

8. The extractive distillation device according to claim 7, characterized in that: The top discharge port of the extractant recovery tower (2) is connected to a third condenser (24), the discharge port of the third condenser (24) is connected to a third reflux tank (25), the discharge port of the third reflux tank (25) is connected to a second collecting tank (26), and is in communication with the top reflux port of the extractant recovery tower (2).

9. The extractive distillation device according to claim 8, characterized in that: Part of the top product of the extractant recovery tower (2) can enter the second feed pipe (38), and another part can enter the third reflux tank (25) after being condensed by the third condenser (24). Part of the product that enters the third reflux tank (25) can enter the second collection tank (26), and another part can enter the extractant recovery tower (2).

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