A maleic acid diethyl ester rectification system and method

Abstract

The application discloses a maleic acid diethyl ester rectification system, which comprises a rectification bin, an evaporation treatment bin and a dehydration bin, the evaporation treatment bin surrounds the tower middle and the tower bottom of the rectification bin, the dehydration bin is installed and surrounds the tower top of the rectification bin, the rectification bin is externally provided with a heat exchange cavity, a heat source is installed at the bottom of the heat exchange cavity, a heat transfer substance capable of diffusing in the heat exchange cavity is filled in the heat exchange cavity, the evaporation treatment bin is installed inside the heat exchange cavity, the evaporation treatment bin comprises a lower evaporation chamber, a plurality of evaporation pipes and a falling film coating chamber, the rectification bin tower bottom is connected with the falling film coating chamber in communication through a material collecting pump, the lower bottom plate of the falling film coating chamber is provided with a coating groove, the evaporation pipes penetrate through the falling film coating chamber and are connected with the dehydration bin, at least one isolation pipe is arranged in the dehydration bin, a steam permeation membrane pipe connected with the evaporation pipe is installed in the isolation pipe, the rectification and the recycling and separation of subsequent materials are highly integrated, the materials can be efficiently separated and treated by the system, the rectification system is simplified as a whole, and the setting and use costs of the rectification system are reduced.

Description

Technical Field

[0001] This invention relates to the field of diethyl maleate technology, and more particularly to a diethyl maleate distillation system and method. Background Technology

[0002] In the existing production process of diethyl maleate, the material after esterification in the reactor needs to be sent to a distillation column for distillation to separate the water and ethanol mixed in the material to obtain a diethyl maleate product with higher purity.

[0003] However, the water and ethanol produced by existing distillation columns are difficult to recover and separate. If further recovery and separation are required, the top material of the column needs to be fed into a separate unit for processing, which increases the complexity of the entire distillation system and also increases the system setup and operating costs. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention provides a diethyl maleate distillation system and method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A diethyl maleate distillation system includes a distillation chamber, an evaporation chamber, and a dehydration chamber. The evaporation chamber surrounds the middle and bottom of the distillation chamber, and the dehydration chamber is installed and surrounds the top of the distillation chamber. The distillation chamber has a heat exchange chamber on its exterior, a heat source is installed at the bottom of the heat exchange chamber, and the heat exchange chamber is filled with a heat transfer medium that can diffuse within the heat exchange chamber. The evaporation chamber is installed inside the heat exchange chamber and includes a lower evaporation chamber, several evaporation tubes, and a falling film coating chamber. The bottom of the distillation chamber is connected to the falling film coating chamber via a collection pump.

[0007] The bottom plate of the falling film coating chamber has a coating trough. The evaporation tube passes through the falling film coating chamber and connects to the dehydration chamber. At least one isolation tube is installed in the dehydration chamber, and a vapor permeation membrane tube connected to the evaporation tube is installed in the isolation tube.

[0008] Preferably, a feed assembly is installed at the top of the distillation column. The feed assembly includes a feed pipe, a dispersion pipe, and a stepping pipe. The feed pipe extends from the top of the distillation column into the column. The stepping pipes are horizontally arranged and installed in the distillation column. Each stepping pipe has multiple downward-facing dispersion outlets. Each stepping pipe is connected to the lower end of the feed pipe through the dispersion pipe.

[0009] Preferably, the bottom plate of the distillation chamber is equipped with an injection assembly, which includes an injection pipe, a retaining plate, and a blocking cover. The injection pipe extends to the outside of the distillation chamber, the retaining plate is arranged around the injection pipe, and the blocking cover covers the top of the retaining plate and is spaced from the upper edge of the retaining plate.

[0010] Preferably, the heat exchange cavity is divided into an inner zone and an outer zone by a surrounding plate. The heat source is located at the bottom of the inner zone of the heat exchange cavity. There is a gap between the upper part of the surrounding plate and the top plate of the heat exchange cavity. The surrounding plate can isolate heat exchange.

[0011] Preferably, the collecting pump is connected to the falling film coating chamber through at least one pump feed pipe, which is installed through the interior of the lower edge evaporation chamber.

[0012] Preferably, the coating tank is disposed close to the inner side of the lower edge of the outer peripheral wall and the inner peripheral wall of the evaporator, and the coating tank is also disposed around the outer peripheral wall of the evaporator tube.

[0013] Preferably, the falling film coating chamber is also provided with at least one vent pipe, which passes through the falling film coating chamber and connects the lower evaporation chamber and the dehydration chamber. The isolation pipe is also provided with an air inlet window that connects the inside and outside of the isolation pipe.

[0014] The present invention further provides a method for distilling diethyl maleate, comprising the following steps:

[0015] S1: Start the heat source to raise the temperature of the distillation chamber and heat exchanger from bottom to top and inject an appropriate amount of ethanol into the bottom of the distillation chamber;

[0016] S2: Inject crude material into the distillation column. After the material collects at the bottom of the column, it is collected by the collection pump and pumped into the falling film coating chamber.

[0017] S3: The material flows down from the falling film coating chamber and removes light components such as ethanol and water in the lower edge evaporation chamber. The heavy components are collected separately and obtained after alkali washing, water washing, dehydration and distillation.

[0018] S4: The light components removed in the lower evaporation chamber and collected at the top of the distillation column flow into the dehydration chamber. The water in the light components passes through the sieve membrane of the vapor permeation membrane tube and is discharged from the system. It is expected to be collected, cooled and then returned to the diethyl maleate esterification reactor.

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

[0020] 1. This invention integrates the distillation of diethyl maleate with the subsequent recovery and separation of materials into a single system. The materials can be efficiently separated and processed by the system, the overall distillation system is simplified, and the setup and operation costs of the distillation system are reduced.

[0021] 2. The evaporation chamber of this invention can simultaneously perform liquid film evaporation and separation in the evaporation tube and the lower evaporation chamber wall. When the material is injected into the falling film coating chamber through the pump pipe, it can also be preheated in the lower evaporation chamber, resulting in high evaporation efficiency during material processing.

[0022] 3. The evaporation tube of the present invention can connect to the vapor permeation membrane tube to form a low pressure inside the vapor permeation membrane tube, thereby expanding the liquid film spreading area of ​​the material in the lower evaporation chamber, improving the evaporation efficiency during material processing, simplifying the transmission pipeline of the distillation system, and reducing the system setup and operating costs. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a three-dimensional sectional view of a diethyl maleate distillation system according to the present invention;

[0025] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0026] Figure 3 for Figure 1 Enlarged diagram at point B

[0027] Figure 4 for Figure 1 Enlarged diagram at point C

[0028] Figure 5 This is an independent three-dimensional sectional view of the evaporation treatment chamber described in this invention from one viewing angle;

[0029] Figure 6 This is an independent three-dimensional sectional view of the evaporation treatment chamber described in this invention from another viewing angle.

[0030] In the diagram: 1. Distillation chamber; 101. Heat exchange chamber; 11. Heat source; 12. Surrounding plate; 2. Evaporation treatment chamber; 201. Coating tank; 21. Lower edge evaporation chamber; 22. Evaporation tube; 23. Falling film coating chamber; 24. Diffuser; 3. Dehydration chamber; 301. Air inlet window; 31. Isolation tube; 32. Vapor permeation membrane tube; 4. Feed assembly; 41. Feed pipe; 42. Dispersion pipe; 43. Stepping pipe; 5. Injection assembly; 51. Injection pipe; 52. Enclosure plate; 53. Barrier cover; 6. Collecting pump; 7. Pump feed pipe. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0032] Reference Figure 1-6 A diethyl maleate distillation system includes a distillation chamber 1, an evaporation chamber 2, and a dehydration chamber 3, wherein the evaporation chamber 2 surrounds the middle and bottom of the distillation chamber 1, and the dehydration chamber 3 is installed on and surrounds the top of the distillation chamber 1.

[0033] The top of the distillation chamber 1 is equipped with a feed assembly 4, which includes a feed pipe 41, a dispersion pipe 42, and step pipes 43. The feed pipe 41 is connected to the diethyl maleate production reactor, and the crude diethyl maleate produced in the reactor is fed into the feed pipe 41. The feed pipe 41 extends from the top of the distillation chamber 1 into the middle of the column. The step pipes 43 are horizontally arranged and installed in the middle of the distillation chamber 1. Each step pipe 43 has multiple downward-facing dispersion outlets. Each step pipe 43 is connected to the lower end of the feed pipe 41 through the dispersion pipe 42. The crude product flows into each step pipe 43 through the dispersion pipe 42 and is finally sprayed downward into the middle of the distillation chamber 1 through the dispersion outlets.

[0034] An injection assembly 5 is installed on the bottom plate of the distillation chamber 1. The injection assembly 5 includes a feed pipe 51, a retaining plate 52, and a blocking cover 53. The feed pipe 51 extends to the outside of the distillation chamber 1, allowing external ethanol to be injected into the distillation chamber 1 through the feed pipe 51. The retaining plate 52 is arranged around the feed pipe 51, and the ethanol injected into the distillation chamber 1 will be temporarily stored in the space divided by the retaining plate 52 in the bottom plate of the distillation chamber 1. The blocking cover 53 covers the retaining plate 52 and is spaced from the upper edge of the retaining plate 52 to allow the ethanol in the retaining plate 52 to be heated and vaporized, and then escape upwards through the gap into the distillation chamber 1. A tray is provided between the bottom of the distillation chamber 1 and the tower bottom. The tray is loaded with a catalyst. The ethanol gas escaping from the bottom of the tower and the material sprayed downwards by the feed pipe 43 can further react under the action of the catalyst. The liquid flow produced by the reaction falls and is blocked by the blocking cover 53, and collects outside the retaining plate 52 at the bottom of the distillation chamber 1.

[0035] The distillation chamber 1 has a heat exchange cavity 101 on its exterior. The heat exchange cavity 101 is filled with a heat transfer medium that can diffuse within the heat exchange cavity 101. The heat exchange cavity 101 is divided into an inner zone and an outer zone by a surrounding plate 12. A heat source 11 is installed at the bottom of the inner zone of the heat exchange cavity 101. The heat source 11 can continuously provide heat to the heat transfer medium in the heat exchange cavity 101. The heat provided by the heat source 11 is conducted upward with the heat transfer medium and also conducted to the inside of the distillation chamber 1 along with the outer peripheral wall of the distillation chamber 1 to heat the inside of the distillation chamber 1.

[0036] It is understandable that the heat emitted by the heat source 11 at the bottom of the heat exchange chamber 101 will gradually be lost during the upward conduction process, and the internal temperature of the heat exchange chamber 101 and the distillation chamber 1 will gradually decrease from bottom to top. There is a gap between the upper part of the surrounding plate 12 and the top plate of the heat exchange chamber 101. The surrounding plate 12 can isolate heat exchange. The heat provided by the heat source 11 will be preferentially transferred to the distillation chamber 1 after being transferred to the heat transfer medium. After spreading upward to the top of the heat exchange chamber 101, it will enter the outer area of ​​the heat exchange chamber 101 to continue heating the device in the outer area of ​​the heat exchange chamber 101.

[0037] The evaporation chamber 2 is installed in the outer area of ​​the heat exchange chamber 101. The evaporation chamber 2 includes a lower edge evaporation chamber 21, a plurality of evaporation tubes 22 and a falling film coating chamber 23. The evaporation tubes 22 are arranged inside the lower edge evaporation chamber 21 and the falling film coating chamber 23 is installed at the upper end of the lower edge evaporation chamber 21.

[0038] A collection pump 6 is installed below the distillation chamber 1. The collection pump 6 is connected to the external space of the enclosure plate 52. After distillation, the material is collected by the collection pump 6 and injected into the falling film coating chamber 23 through at least one pump feed pipe 7. The pump feed pipe 7 passes through the lower edge of the evaporation chamber 21 and is connected to the falling film coating chamber 23. The material can be preheated before entering the falling film coating chamber 23 through the pump feed pipe 7.

[0039] The falling film coating chamber 23 has a coating tank 201 on its bottom plate. The coating tank 201 is set close to the outer peripheral wall and the inner side of the inner peripheral wall of the lower edge evaporation chamber 21. The material injected into the falling film coating chamber 23 can pass through the coating tank 201 and flow down close to the inner wall of the lower edge evaporation chamber 21 to form a liquid film. During the downward flow, the liquid film is heated by the lower edge evaporation chamber 21, and light component impurities such as water and ethanol in the material will be removed. The heavy component material that continues to flow down is collected separately. After alkaline washing, water washing, dehydration and distillation, the finished product diethyl maleate is obtained.

[0040] It is worth mentioning that the coating tank 201 is also arranged around the evaporation tube 22 that penetrates the falling film coating chamber 23, so that the material can flow down along the outer wall of the evaporation tube 22 to form a film, thereby further improving the material separation efficiency.

[0041] The falling film coating chamber 23 is also provided with at least one escaping pipe 24. The escaping pipe 24 passes through the falling film coating chamber 23 and connects the lower evaporation chamber 21 with the dehydration chamber 3. The light components of water and ethanol that are separated from the material will pass through the escaping pipe 24 and float upward into the dehydration chamber 3.

[0042] The dehydration chamber 3 is equipped with at least one isolation pipe 31. A vapor permeation membrane pipe 32, connected to the evaporation pipe 22, is installed inside the isolation pipe 31. The isolation pipe 31 is also connected to the top of the distillation chamber 1 and has an air inlet window 301 connecting to the outside. Material drifting upwards from the lower edge of the evaporation chamber 21 into the dehydration chamber 3, as well as material accumulating at the top of the distillation chamber 1 after distillation, enters the isolation pipe 31. The lower end of the evaporation pipe 22 is connected to an external low-pressure generating device to reduce the internal pressure of the vapor permeation membrane pipe 32. Moisture in the material inside the isolation pipe 31 will pass through the membrane of the vapor permeation membrane pipe 32 and enter the vapor permeation membrane pipe 32, and then be discharged to the outside of the system through the evaporation pipe 22.

[0043] The material in the isolation tube 31 can be collected after dehydration and returned to the reaction vessel for the production of diethyl maleate to continue the esterification reaction.

[0044] A method for distilling diethyl maleate includes the following steps:

[0045] S1: Start the heat source 11 to raise the temperature of the distillation chamber 1 and the heat exchange chamber 101 from bottom to top and inject an appropriate amount of ethanol into the enclosure 52;

[0046] S2: Crude material is injected into the distillation chamber 1 through the feed assembly 4. After the material is collected at the bottom of the column, it is collected by the collection pump 6 and pumped into the falling film coating chamber 23.

[0047] S3: The material flows down from the falling film coating chamber 23 and removes light components such as ethanol and water in the lower edge evaporation chamber 21. The heavy components are collected separately and obtained after alkali washing, water washing, dehydration and distillation.

[0048] S4: The light components removed in the lower evaporation chamber 21 and collected at the top of the distillation chamber 1 flow into the dehydration chamber 3. The water in the light components passes through the sieve membrane of the vapor permeation membrane tube 32 and is discharged from the system. It is expected to be collected, cooled and then returned to the diethyl maleate esterification reactor.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] The control method of this invention is automatic control through a controller. The control circuit of the controller can be implemented by simple programming by those skilled in the art. The power supply is also common knowledge in the art. Furthermore, since this invention is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0052] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A maleic acid diethyl ester rectification system, comprising a rectification bin (1), an evaporation treatment bin (2) and a dehydration bin (3), the evaporation treatment bin (2) surrounding the middle and bottom of the rectification bin (1), and the dehydration bin (3) being installed and surrounding the top of the rectification bin (1), characterized in that: the rectification bin (1) is externally provided with a heat exchange cavity (101), the bottom of the heat exchange cavity (101) is provided with a heat source (11), and the heat exchange cavity (101) is filled with a heat transfer medium capable of diffusing in the heat exchange cavity (101), the evaporation treatment bin (2) is installed inside the heat exchange cavity (101), and the evaporation treatment bin (2) comprises a lower evaporation chamber (21), a plurality of evaporation pipes (22) and a falling film coating chamber (23), and the bottom of the rectification bin (1) is connected with the falling film coating chamber (23) through a collecting pump (6); the lower bottom plate of the falling film coating chamber (23) is provided with a coating groove (201), the evaporation pipes (22) penetrate through the falling film coating chamber (23) to communicate with the dehydration bin (3), at least one isolation pipe (31) is arranged in the dehydration bin (3), and a steam permeation membrane pipe (32) communicating with the evaporation pipe (22) is arranged in the isolation pipe (31). The top of the rectification bin (1) is provided with a feeding assembly (4), the feeding assembly (4) comprises a feeding pipe (41), a dispersion pipe (42) and a distribution pipe (43), the feeding pipe (41) extends into the middle of the rectification bin (1) from the top of the rectification bin (1), the distribution pipes (43) are horizontally arranged in the middle of the rectification bin (1), each distribution pipe (43) is provided with a plurality of downward dispersion liquid outlets, and each distribution pipe (43) is connected with the lower end of the feeding pipe (41) through the dispersion pipe (42).

2. The maleic acid diethyl ester rectification system of claim 1, wherein: The bottom plate of the rectification bin (1) is provided with an injection assembly (5), the injection assembly (5) comprises an injection pipe (51), a surrounding plate (52) and a blocking cover (53), the injection pipe (51) extends out of the rectification bin (1), the surrounding plate (52) is arranged around the injection pipe (51), and the blocking cover (53) covers the upper part of the surrounding plate (52) and is spaced from the upper edge of the surrounding plate (52).

3. The maleic acid diethyl ester rectification system of claim 1, wherein: The heat exchange cavity (101) is divided into an inner zone and an outer zone by a surrounding plate (12), the heat source (11) is arranged at the bottom of the inner zone of the heat exchange cavity (101), and the surrounding plate (12) has a gap between the upper part of the surrounding plate (12) and the top plate of the heat exchange cavity (101), and the surrounding plate (12) can isolate heat exchange.

4. The maleic acid diethyl ester rectification system of claim 1, wherein: The collecting pump (6) is connected with the falling film coating chamber (23) through at least one pump pipe (7), and the pump pipe (7) penetrates through the inside of the lower evaporation chamber (21).

5. The maleic acid diethyl ester rectification system of claim 1, wherein: The coating groove (201) is arranged close to the inner side of the outer peripheral wall and the inner peripheral wall of the lower evaporation chamber (21), and the coating groove (201) is also arranged around the outer peripheral wall of the evaporation pipe (22).

6. The maleic acid diethyl ester rectification system of claim 1, wherein: ​ 7. The maleic acid diethyl ester rectification system of claim 1, wherein: At least one dissipating pipe (24) is arranged in the falling film coating chamber (23), which penetrates the falling film coating chamber (23) and connects the lower evaporation chamber (21) and the dehydration bin (3), and the isolation pipe (31) is also provided with an air inlet window (301) for connecting the inside and outside of the isolation pipe (31).

8. A method for rectifying diethyl maleate using the diethyl maleate rectification system according to any one of claims 1 to 7, characterized by, The method comprises the following steps: S1: starting the heat source (11) to heat the rectification bin (1) and the heat exchange cavity (101) from bottom to top, and injecting appropriate amount of ethanol into the bottom of the rectification bin (1); S2: injecting the crude material into the rectification bin (1), collecting the material at the bottom of the tower by the material collecting pump (6) and pumping the material into the falling film coating chamber (23); S3: the material flows down from the falling film coating chamber (23) and removes the light components such as ethanol and water in the lower evaporation chamber (21), and the heavy components are collected separately, washed with alkali, washed with water, dehydrated, rectified and obtained as the finished product; S4: the light components removed in the lower evaporation chamber (21) and collected at the top of the rectification bin (1) flow into the dehydration bin (3), and the water in the light components is discharged from the system through the screen membrane of the steam permeation membrane pipe (32), and the collected and cooled light components are returned to the maleic acid diethyl ester esterification reactor.

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