A reactive distillation column

Abstract

This invention discloses a reactive distillation column suitable for gas-liquid-solid reactions involving counter-current gas-liquid contact. It comprises: a sieve plate fixed to the inner wall of the column, allowing rising gas phase to pass through; a basket located above the sieve plate, supporting horizontally staggered packing and catalyst; a descending unit located above the basket, providing descending liquid phase; and an impeller located in the space between the sieve plate and the basket, generating a centrifugal swirling effect when the gas and liquid phases counter-currently contact within the packing and catalyst. This invention effectively improves mass transfer reaction efficiency through the centrifugal swirling effect.

Description

Technical Field

[0001] This invention relates to the field of oil refining and chemical technology, and in particular to a reactive distillation column. Background Technology

[0002] Reactive distillation columns play a crucial role in petroleum refining and chemical production. During the reactive distillation process, multiple feed streams mix, transfer mass, and react. Simultaneously, reaction products and by-products are separated within the column based on their different boiling points, thus achieving the goal of simultaneous chemical reaction and product separation.

[0003] For example, Chinese patent CN205046018U discloses an apparatus for producing high-purity isobutylene using a novel structured packing material. The apparatus includes a catalytic reactive distillation column, which has a catalytic rectification section and a stripping section arranged from top to bottom. The catalytic rectification section is filled with several layers of packing material containing a catalyst, while the stripping section is filled with several layers of packing material without a catalyst. Each packing layer includes two components: a first component and a second component. The first component is a windowed flow-guiding packing sheet, and the second component is a structured packing sheet. This catalytic reactive distillation column uses windowed flow-guiding structured packing material, which effectively increases the gas-liquid mass transfer area and improves the gas-liquid mass transfer rate.

[0004] The primary challenge in reactive distillation columns is improving mass transfer between substances and increasing reaction rates. Currently, the most widely used methods in refineries and chemical plants are adding solid packing material to the trays to enhance mass transfer and adding catalysts to increase chemical reaction rates. However, existing methods simply stack packing or catalysts on the trays, which, limited by column height and material flow conditions, offers only limited improvement in mass transfer and reaction efficiency. Increasing the number of trays, on the other hand, increases production costs.

[0005] Many methods exist for improving the mass transfer efficiency of single-layer trays, but most involve staggering the packing and catalyst layers. Based on the liquid flow direction, the distribution of packing and catalyst layers can be categorized into longitudinal and transverse distributions. Liquid flows downwards from the upper tray, while gas flows upwards from the lower tray, passing sequentially through each packing or catalyst layer to achieve a synergistic effect of enhanced mass transfer and increased reaction rate. However, both distribution methods are limited by the height and diameter of the single-layer column, and the thickness of the packing or catalyst and the number of staggered layers are also limited. Increasing the thickness of the packing or catalyst reduces the number of staggered layers, resulting in a poorer synergistic effect on mass transfer; conversely, increasing the number of staggered layers leads to higher construction costs and increased operational difficulty.

[0006] Therefore, there is an urgent need for a reactive distillation column with high mass transfer efficiency on a single tray, suitable for gas-liquid-solid reactions with countercurrent gas-liquid contact.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a reactive distillation column suitable for gas-liquid-solid reactions, which can effectively improve the mass transfer reaction efficiency through centrifugal swirl.

[0009] To achieve the above objectives, according to a first aspect of the present invention, a reactive distillation column is provided, suitable for gas-liquid-solid reactions with counter-current gas-liquid contact, comprising: a sieve plate fixed to the inner wall of the reactive distillation column, allowing rising gas phase to pass through; a basket located above the sieve plate for supporting horizontally staggered packing and catalyst; a descending unit located above the basket for providing descending liquid phase; and an impeller located in the space between the sieve plate and the basket for generating a centrifugal swirling effect when the gas and liquid are in counter-current contact in the packing and catalyst.

[0010] Furthermore, in the above technical solution, the impeller can be driven to rotate by a central shaft that is located in the center of the reactive distillation column and runs through it.

[0011] Furthermore, in the above technical solution, the liquid downcomer unit may include: a liquid downcomer connecting horizontal pipe, the inlet of which is located on one side of the inner wall of the tower, and the outlet is connected to the inlet of the liquid downcomer vertical pipe; a liquid downcomer vertical pipe, which is penetrated by a central axis to form an annular space, the annular space extending vertically along the central axis, and the liquid phase entering from the inlet of the liquid downcomer connecting horizontal pipe and descending along the annular space.

[0012] Furthermore, in the above technical solution, the portion of the central shaft located inside the downcomer is provided with external threads, which are used to form a spiral descent effect of the liquid phase in the annular space during the downcomer process.

[0013] Furthermore, in the above technical solution, the outlet of the downcomer can be designed as a gradually expanding structure, and the spirally descending liquid phase forms a swirling effect at the outlet of the downcomer.

[0014] Furthermore, in the above technical solution, the outlet of the downcomer is located below the liquid surface, and the swirling flow agitates the liquid phase located above the basket.

[0015] Furthermore, in the above technical solution, the basket can be fixed to the inner wall of the tower, and the basket can be divided into multiple regions. These multiple regions can be fan-shaped regions evenly spaced along the circumference, with adjacent fan-shaped regions filled with packing material and catalyst, respectively. During the process of the gas and liquid streams running along the circumference of the basket under the action of centrifugal vortex, they can pass through each fan-shaped region in sequence, forming an alternating process of enhanced mass transfer between the packing material and the catalyst accelerating the gas-liquid reaction.

[0016] Furthermore, in the above technical solution, the basket can be divided into multiple regions, which can also be annular regions spaced radially apart, with adjacent annular regions filled with packing material and catalyst, respectively. During the radial movement of the gas and liquid streams along the basket under the action of centrifugal vortex, they can sequentially pass through each annular region, forming an alternating process of enhanced mass transfer between the packing material and the accelerated reaction of the catalyst.

[0017] Furthermore, in the above technical solution, one end of the central shaft extends to the outside of the reactive distillation column and is connected to the motor. The motor can be a forward and reverse rotating motor. When the motor rotates in the reverse direction, the impeller drives the liquid to flow in the opposite direction and impacts the packing and catalyst in the opposite direction to form agitation.

[0018] Furthermore, in the above technical solution, when the impeller speed or gas-liquid density difference is lower than the threshold, the pores on the sieve plate have the same diameter and are evenly spaced; when the impeller speed or gas-liquid density difference is higher than the threshold, the pore diameter and number on the sieve plate gradually increase outward in the radial direction.

[0019] Furthermore, in the above technical solution, the sieve plate, the basket, the liquid downcomer and the impeller constitute a gas-liquid mass transfer reaction unit. In the reactive distillation column, one or more gas-liquid mass transfer reaction units can be set up.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The present invention can generate a spiral upward airflow by rotating the impeller. At the same time, the impeller is located close to the bottom of the basket, which can also generate a centrifugal swirling effect when the gas and liquid come into countercurrent contact in the packing and catalyst. The gas and liquid can stay dynamically in the packing and catalyst for a long time, forming circumferential and radial movement in the basket. When the gas and liquid run in the voids of the packing, the gas-liquid mass transfer efficiency can be effectively enhanced. When the gas and liquid run in the voids of the catalyst, the gas-liquid reaction efficiency can be effectively improved.

[0022] 2) In this invention, the outlet of the downcomer is set below the liquid surface. On the one hand, it can prevent the rising gas phase from entering the downcomer. On the other hand, the swirling flow at the outlet of the downcomer can agitate the accumulated liquid phase in the same direction, so that the liquid phase enters the lower basket in a spiral state. The liquid phase has a longer residence time in the packing and catalyst of the basket. Combined with the gas-liquid centrifugal swirling effect generated by the impeller, it can further improve the gas-liquid mass transfer reaction efficiency.

[0023] 3) The basket of the present invention adopts a fan-shaped area arrangement. Under the action of centrifugal swirling flow, the two streams of gas and liquid can pass through each fan-shaped area in sequence as they run along the circumference of the basket. This forms an alternating process of enhanced mass transfer between the packing material and accelerated reaction between the catalyst and the gas, thereby achieving efficient mass transfer and reaction between the gas and liquid. Alternatively, by adopting an annular area arrangement, the two streams of gas and liquid can pass through each annular area in sequence as they run along the radial direction of the basket under the action of centrifugal swirling flow. This also forms an alternating process of enhanced mass transfer between the packing material and accelerated reaction between the catalyst and the gas, thereby achieving efficient mass transfer and reaction between the gas and liquid.

[0024] 4) The design of the air holes on the sieve plate of the present invention can be adopted in a way that the diameter and number gradually increase outward in the radial direction. When the impeller speed is fast or the density difference between gas and liquid reactants is large, this design can effectively avoid the transverse stratification of gas and liquid during the centrifugal swirling process, and avoid the reduction of gas-liquid contact area, which would affect the gas-liquid mass transfer reaction.

[0025] 5) This invention uses a forward and reverse rotating motor to drive the impeller. By changing the rotation direction of the impeller, the fluid can flow in the opposite direction, thereby achieving a reverse impact on the filling material and forming agitation. This can effectively utilize the deep material in the basket, maximize the mass transfer reaction efficiency, extend the service life of the filling material, reduce the agent replacement cycle, and reduce production costs.

[0026] 6) The reactive distillation column of the present invention combines centrifugal swirl with enhanced mass transfer by packing and accelerated reaction by catalyst, which can effectively improve the mass transfer reaction efficiency within a single-layer sieve plate, increase the reaction conversion rate within the reactive distillation column, and save production costs; it can improve the synergistic effect of packing mass transfer and catalytic reaction, meet the flexibility requirements of reactive distillation columns under different reaction conditions and product demands, and make the adjustment and modification of reactive distillation columns simpler and more applicable; moreover, it has a simple structure and is easy to operate.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the reactive distillation column of the present invention.

[0029] Figure 2 This is a schematic diagram of the internal structure of the reactive distillation column of the present invention.

[0030] Figure 3 This is a top view schematic diagram of one embodiment of the sieve plate in the reactive distillation column of the present invention (the top view structure of the downcomer unit is also shown).

[0031] Figure 4 This is a top view schematic diagram of another embodiment of the sieve plate in the reactive distillation column of the present invention (the top view structure of the downcomer unit is also shown).

[0032] Figure 5-A This is a schematic diagram of the first embodiment of the basket-shaped sector partition in the reactive distillation column of the present invention.

[0033] Figure 5-B This is a schematic diagram of the second embodiment of the fan-shaped partitioning of the basket in the reactive distillation column of the present invention.

[0034] Figure 5-C This is a schematic diagram of the first embodiment of the annular partitioning of the basket in the reactive distillation column of the present invention.

[0035] Figure 5-D This is a schematic diagram of the second embodiment of the annular partitioning of the basket in the reactive distillation column of the present invention.

[0036] Explanation of key figure labels:

[0037] 1-Reactive distillation column, 11-Sieve plate, 111-Vacuum pores, 12-Basin, 121-Packing, 122-Catalyst, 13-Downcoming unit, 131-Downcoming connecting horizontal pipe, 1310-Horizontal pipe inlet, 132-Downcoming vertical pipe, 1320-Vertical pipe outlet, 14-Impeller, 140-Central shaft, 2-Liquid phase inlet, 3-Gas phase inlet, 4-Gas phase outlet, 5-Liquid phase outlet, 6-Motor. Detailed Implementation

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0039] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0040] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0041] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0042] like Figure 1 As shown, this invention provides a reactive distillation column 1 suitable for gas-liquid-solid reactions involving countercurrent gas-liquid contact. This invention utilizes a reactive distillation column for centrifugal cyclone-enhanced mass transfer reactive distillation. The reactive distillation process for different systems is as follows: Low-boiling-point reactants (i.e., gaseous feed) enter from the lower gas phase inlet 3 of the column and move upwards in gaseous form; high-boiling-point reactants (i.e., liquid feed) enter from the upper liquid phase inlet 2 of the column and flow downwards in liquid form. The two reactants contact countercurrently to achieve mass transfer. Reaction products and byproducts are discharged from the top gas phase outlet 4 or the bottom liquid phase outlet 5, respectively, depending on their boiling point differences. To improve gas-liquid mass transfer and reaction efficiency, packing and catalyst are installed along the gas-liquid flow path in the reactive distillation column 1. The column body of this invention is a cylindrical, closed space. In addition to the above gas-liquid inlet and outlet, a condensate reflux inlet, a reboiler reflux inlet, a side stream outlet, and a side stream inlet (not shown in the figure) can be provided as needed. This invention uses a central shaft 140 located in the center of the tower body and extending through it to drive the impeller 14 to rotate (see reference). Figure 2 This generates the centrifugal vortex effect of the present invention. The lower end of the central shaft 140 extends out of the tower body and is connected to the motor 6, providing rotational power to the impeller 14.

[0043] Further as Figure 2As shown, the reactive distillation column 1 of the present invention includes a sieve plate 11, a basket 12, a downcomer unit 13, and an impeller 14. The sieve plate 11 is fixed to the inner wall of the reactive distillation column 1, allowing rising gas phase to pass through. The basket 12 is located above the sieve plate 11 and supports the horizontally staggered packing material 121 and catalyst 122. The downcomer unit 13 is located above the basket 12 and provides descending liquid phase. The impeller 14 is located in the space between the sieve plate 11 and the basket 12, and is used to generate a centrifugal swirling effect when the gas and liquid come into counter-current contact in the packing material and catalyst.

[0044] Further as Figure 2 As shown, the sieve plate 11, the basket 12, the liquid descending unit 13, and the impeller 14 constitute a gas-liquid mass transfer reaction unit. In the reactive distillation column 1 of the present invention, one or more such gas-liquid mass transfer reaction units can be provided. If multiple units are provided, they are arranged in upper and lower layers.

[0045] Further as Figure 3 As shown, the sieve plate 11 can be provided with uniformly distributed pores 111. The pores 111 allow the rising gas phase to enter above the sieve plate through the pores. During the upward flow of the gas phase, as it passes over the sieve plate 11, it is dispersed into multiple continuous gas streams or bubble streams by the pores 111, thereby uniformly dispersing the rising gas above the sieve plate, increasing the gas-liquid contact area, and improving the gas-liquid mass transfer reaction efficiency. Due to the pressure of the rising gas phase at the pores, the liquid phase cannot descend through the pores 111. The sieve plate 11 can be designed in an umbrella shape (see reference). Figure 2 This allows the liquid phase above to quickly converge at the outer edge of the sieve plate, and the liquid phase enters the downcomer unit 13 only through the horizontal pipe inlet 1310 on one side of the edge of the sieve plate 11. The distribution and size of the openings of the vent 111 can be determined based on factors such as the impeller speed 14, the gas-liquid density difference, the structure of the basket 12, and the gas flow rate. The sieve plate has a central hole for the central shaft 140 to pass through, and the central hole and the central shaft 140 are sealed together.

[0046] Further as Figure 2 As shown, since the impeller 14 is located in the space between the sieve plate 11 and the basket 12, the gas phase rising from the sieve plate vents 111 is agitated by the impeller 14, forming a spiral upward airflow. At the same time, the impeller 14 is located relatively close to the bottom of the basket 12. The rotation of the impeller can generate a centrifugal swirling effect when the gas and liquid come into countercurrent contact in the packing 121 and the catalyst 122. The gas and liquid can not only stay in the packing and catalyst for a long time, but this stay is dynamic, that is, the gas and liquid can also form circumferential and radial movements within the basket. When the gas and liquid run in the packing voids, the gas-liquid mass transfer efficiency can be effectively enhanced. When the gas and liquid run in the catalyst voids, the gas-liquid reaction efficiency can be effectively improved.

[0047] Further as Figure 2As shown, preferably but not limitingly, the downcomer unit may include a downcomer connecting horizontal pipe 131 and a downcomer vertical pipe 132. The inlet 1310 of the downcomer connecting horizontal pipe 131 is located on one side of the inner wall of the tower, and the outlet is connected to the inlet of the downcomer vertical pipe 132. The downcomer vertical pipe 132 forms an annular space after being penetrated by the central shaft 140. This annular space extends vertically along the central shaft 140. The liquid phase can enter from the inlet 1310 of the downcomer connecting horizontal pipe, first flow laterally through the downcomer connecting horizontal pipe, and then descend along the annular space. Preferably but not limitingly, the portion of the central shaft 140 located inside the downcomer vertical pipe 132 is provided with external threads (not shown in the figure). As the central shaft 140 rotates, these external threads can be used to create a spiral descent effect of the liquid phase in the annular space during the downcomer process. Furthermore, the outlet 1320 of the downcomer vertical pipe 132 has a gradually expanding structure, and the spirally descending liquid phase can form a swirling effect at the outlet of the downcomer vertical pipe 1320. Since the liquid phase can accumulate above the basket 12, the present invention sets the outlet 1320 of the downcomer 132 below the liquid surface. This can prevent the rising gas phase from entering the downcomer 132, and the swirling flow at the outlet 1320 of the downcomer can agitate the accumulated liquid phase in the same direction, so that the liquid phase enters the basket 12 below in a spiral state. The residence time of the liquid phase in the packing and catalyst of the basket is longer. Combined with the gas-liquid centrifugal swirling effect generated by the impeller 14, the gas-liquid mass transfer reaction efficiency can be further improved.

[0048] Further as Figure 5-A and Figure 5-B As shown, the basket 12 is fixed to the inner wall of the tower and is divided into multiple regions. Preferably, but not limited to, the multiple regions are fan-shaped regions evenly spaced along the circumference, and adjacent fan-shaped regions are filled with packing material 121 and catalyst 122, respectively. Figure 5-A The first implementation method sets up four sector-shaped areas. Figure 5-B The second implementation method involves setting up eight sector-shaped regions. With this sector-shaped region arrangement, the gas and liquid streams can pass through each sector sequentially as they move circumferentially along the basket 12 under the action of centrifugal swirling flow. This creates an alternating process of enhanced mass transfer between the packing material and the accelerated reaction by the catalyst. In other words, the swirling fluid can sequentially, repeatedly, and circulate through the sector-shaped packing and catalyst regions within the basket 12, thereby achieving highly efficient mass transfer and reaction between the gas and liquid.

[0049] Further as Figure 5-C and Figure 5-D As shown, preferably but not limitingly, the multiple separated regions can also be annular regions arranged radially spaced apart, with adjacent annular regions filled with filler 121 and catalyst 122, respectively. Figure 5-C The first implementation method sets up four annular areas. Figure 5-DThe second embodiment of the invention sets up two annular regions. With the annular region arrangement, the gas and liquid fluids, under the action of centrifugal swirling flow, run radially along the basket 12 and pass through each annular region in sequence. This can also form an alternating process of enhanced mass transfer between the packing and the catalyst, that is, the swirling fluid can flow sequentially through the annular packing region and the catalyst region in the basket 12, thereby achieving efficient mass transfer and reaction between the gas and liquid.

[0050] Furthermore, the motor 6 driving the central shaft 140 of this invention is preferably a reversible motor. In the initial operating state, the motor is always rotating forward. The rotation of the impeller 14 causes the gas and liquid to form a centrifugal vortex. Under the action of the centrifugal vortex, the gas and liquid generate circumferential and radial movements in the packing and catalyst of the basket 12, realizing the alternating process of enhanced gas-liquid mass transfer and accelerated reaction. After running for a period of time, the packing and / or catalyst on the liquid surface (i.e., the fluid inflow surface) will be affected by factors such as trace impurities, reducing the activity of the packing and catalyst. In contrast, the materials or catalyst inside the non-liquid surface or the packing material still retain higher activity. At this time, reversing the motor 6 can drive the fluid to flow in the opposite direction by changing the rotation direction of the impeller, realizing the reverse impact on the packing material and forming agitation. This can effectively utilize the deep materials in the basket, maximize the mass transfer reaction efficiency, extend the service life of the packing material, reduce the catalyst replacement cycle, and reduce production costs.

[0051] Further research by the inventors revealed that when the impeller 14 of this invention generates centrifugal swirling flow, if the impeller speed is too high or the density difference between the gas and liquid reactants is large, transverse stratification of gas and liquid occurs during the centrifugal swirling flow, resulting in a reduction in the gas-liquid contact area and affecting the gas-liquid mass transfer reaction. In this case, the impeller speed can be appropriately reduced to ensure uniform gas-liquid dispersion and prevent stratification. Specifically, when the impeller speed or the gas-liquid density difference is below a certain threshold, the air holes 111 on the sieve plate 11 can be arranged in a manner with consistent diameter and uniform spacing (i.e.,...). Figure 3 (As shown in the diagram). If it is necessary to maintain a high impeller speed or a large density difference between the gas and liquid reactants, the size and number of openings at the edge of the sieve plate 11 can be increased, while the number and size of openings at the center are relatively smaller. This allows most of the gas flow to enter from the edge of the sieve plate 11, with the gas phase flowing towards the center under centrifugal force and the liquid phase flowing towards the edge under centrifugal force, resulting in transverse countercurrent flow of gas and liquid on the sieve plate, thereby improving the mass transfer reaction efficiency. That is, when the impeller speed or the gas-liquid density difference is higher than a certain threshold, the design of the pores 111 on the sieve plate 11 can be such that the diameter and number gradually increase outward in the radial direction.

[0052] The reactive distillation column of this invention can calculate the reaction rate and mass transfer rate based on the properties of reactants, packing material, catalyst, fluid flow rate, temperature, and column dimensions during actual operation. This allows for the design of impeller speed, packing material, and catalyst partitioning to maximize the mass transfer efficiency within a single sieve plate. This reactive distillation column combines centrifugal vortexing with enhanced mass transfer through packing and accelerated reaction through catalyst, effectively improving the mass transfer efficiency within a single sieve plate, increasing the reaction conversion rate, and saving production costs. This invention enhances the synergistic effect of packing mass transfer and catalytic reaction, meeting the flexibility requirements of different reaction conditions and product demands for the reactive distillation column. The adjustment and modification of the reactive distillation column are simpler, and its applicability is wider. The reactive distillation column of this invention has a simple structure and is easy to operate.

[0053] Example 1

[0054] The reactive distillation column of this invention reacts monomethyl maleate (MMM) with methanol to produce dimethyl maleate (DMM). Liquid reactants MMM and methanol are mixed in a specific ratio and enter the reactive distillation column 1 through liquid inlet 2, while gaseous methanol enters the column through gas inlet 3. The MMM and methanol mixture flows downwards in a liquid state and upwards in a gaseous state, forming a countercurrent mass transfer reaction process throughout the column.

[0055] This embodiment employs multiple gas-liquid mass transfer reaction units. Within a certain sieve plate 11 of the reactive distillation column, liquid reactants (MMM and methanol) and products (DMM and water) flowing in from the upper sieve plate through the downcomer 13 enter the liquid phase layer of this gas-liquid mass transfer reaction unit. Gaseous reactants and products flowing in from the lower sieve plate 11 disperse into the liquid phase layer of this gas-liquid mass transfer reaction unit. Under the action of the impeller 14, the liquid and gaseous reactants and products undergo centrifugal swirling motion within the housing 12, cyclically and alternately contacting the packing 121 and catalyst 122 within the housing 12. This allows the unreacted MMM and methanol in this layer to further react, generating DMM and water. Finally, high-purity liquid DMM is obtained at the bottom liquid outlet of the column, while gaseous methanol and water vapor are discharged at the top, accompanied by a certain amount of gaseous DMM.

[0056] Example 2

[0057] In the reactive distillation column of this invention, after a period of time, the yield of the bottom product decreases significantly due to the reaction of monomethyl maleate (MMM) and methanol to produce dimethyl maleate (DMM), indicating deactivation of the catalyst and packing. At this point, the impeller 14 is rotated in the reverse direction at its original speed, causing the liquid flow in each gas-liquid mass transfer reaction unit to redirect, thereby improving the utilization efficiency of the unused or minimally used catalyst and packing in the deeper parts of the column.

[0058] During the initial stage of impeller 14 reversal, a brief decrease in bottom product yield may occur. This is because the instantaneous reversal causes the centrifugal swirling effect of the liquid flow in each layer of the column to temporarily disappear. During this process, the contact time between the liquid flow in each layer of the column and the packing material in the housing 12 is shortened, the synergistic effect of mass transfer reaction is deteriorated, and the bottom product yield decreases temporarily. However, once the reverse rotation stabilizes, the bottom product yield will gradually recover and approach the initial operating level, thereby extending the service life of the catalyst and packing material, reducing the catalyst replacement cycle and production costs.

[0059] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A reactive distillation column, characterized in that, Gas-liquid-solid reactions applicable to counter-current gas-liquid contact include: A sieve plate, which is fixed to the inner wall of the reactive distillation column, allows the rising gas phase to pass through; The basket, located above the sieve plate, is used to support the horizontally staggered packing material and catalyst; A descending liquid unit, located above the basket, is used to provide descending liquid phase; An impeller, located in the space between the sieve plate and the basket, is used to generate a centrifugal swirling effect when the gas and liquid come into countercurrent contact in the packing and catalyst; the impeller is driven to rotate by a central shaft that is set in the center of the reactive distillation column and runs through it; The downcomer unit includes: a downcomer connecting horizontal pipe with its inlet located on one side of the inner wall of the tower and its outlet connected to the inlet of the downcomer vertical pipe; a downcomer vertical pipe, which is penetrated by the central axis to form an annular space, the annular space extending vertically along the central axis, the liquid phase entering from the inlet of the downcomer connecting horizontal pipe and descending along the annular space; the portion of the central axis inside the downcomer vertical pipe is provided with external threads to create a spiral descent effect of the liquid phase in the annular space during the downcomer process; the outlet of the downcomer vertical pipe has a gradually expanding structure, and the spirally descending liquid phase creates a swirling effect at the outlet of the downcomer vertical pipe; the outlet of the downcomer vertical pipe is located below the liquid surface, and the swirling effect agitates the liquid phase above the basket.

2. The reactive distillation column according to claim 1, characterized in that, The basket is fixed to the inner wall of the tower and is divided into multiple regions. The multiple regions are fan-shaped regions that are evenly spaced along the circumference, and adjacent fan-shaped regions are filled with the packing material and catalyst, respectively.

3. The reactive distillation column according to claim 2, characterized in that, As the gas and liquid streams move circumferentially along the basket under the action of centrifugal vortex, they pass through each of the aforementioned sector regions in sequence, forming an alternating process of enhanced mass transfer of gas and liquid by the packing material and accelerated reaction of gas and liquid by the catalyst.

4. The reactive distillation column according to claim 1, characterized in that, The basket is divided into multiple regions, which are annular regions spaced apart radially, and adjacent annular regions are filled with the filler and catalyst, respectively.

5. The reactive distillation column according to claim 4, characterized in that, As the gas and liquid fluids move radially along the basket under the action of centrifugal swirling flow, they pass through each of the aforementioned annular regions in sequence, forming an alternating process of enhanced mass transfer of gas and liquid by the packing material and accelerated reaction of gas and liquid by the catalyst.

6. The reactive distillation column according to claim 1, characterized in that, One end of the central shaft extends to the outside of the reactive distillation column and is connected to a motor. The motor is a forward and reverse rotating motor. When the motor rotates in the reverse direction, the impeller drives the liquid to flow in the opposite direction and impacts the packing and catalyst in the opposite direction to form agitation.

7. The reactive distillation column according to claim 1, characterized in that, When the impeller speed or gas-liquid density difference is below the threshold, the pores on the sieve plate are of uniform diameter and evenly spaced; when the impeller speed or gas-liquid density difference is above the threshold, the pore diameter and number on the sieve plate gradually increase outward in the radial direction.

8. The reactive distillation column according to claim 1, characterized in that, The sieve plate, basket, liquid downcomer and impeller constitute a gas-liquid mass transfer reaction unit. In the reactive distillation column, one or more gas-liquid mass transfer reaction units are provided.

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