CN117618955A - Reactive distillation column - Google Patents

Abstract

The invention discloses a reactive rectifying tower, which is suitable for gas-liquid-solid reaction of gas-liquid reverse contact, and comprises the following steps: a sieve plate fixed on the inner wall of the reactive distillation column, allowing the ascending gas phase to pass through; the basket body is positioned above the screen plate and used for supporting the filling materials and the catalysts which are transversely staggered; a liquid dropping unit located above the housing for providing a dropped liquid phase; and the impeller is positioned in the space between the sieve plate and the basket body and is used for generating centrifugal swirl effect when gas and liquid reversely contact with the filler and the catalyst. The invention can effectively improve the mass transfer reaction efficiency through the centrifugal rotational flow.

Description

Reactive distillation column

Technical Field

The invention relates to the technical field of oil refining and chemical industry, in particular to a reaction rectifying tower.

Background

The reactive rectifying tower plays an important role in petroleum refining and chemical production, and in the raw material reactive rectifying process, multiple feeds are mutually mixed and transferred and react. At the same time, the reaction product and the side reaction product are rectified and separated in the tower according to the difference of boiling points, thereby realizing the purpose of simultaneously carrying out chemical reaction and product separation.

For example, chinese patent CN205046018U discloses a device for preparing high-purity isobutene by using novel structured packing, which comprises a catalytic reaction rectifying tower, wherein a catalytic rectifying section and a stripping section are arranged in the catalytic reaction rectifying tower from top to bottom, a plurality of layers of packing with catalyst are filled in the catalytic rectifying section, a plurality of layers of packing without catalyst are filled in the stripping section, each layer of packing layer comprises two components, namely a first component and a second component, wherein the first component is a windowed guide packing sheet, and the second component is a structured packing sheet. The packing of the catalytic reaction rectifying tower adopts windowed flow guide type structured packing, so that the gas-liquid mass transfer area can be effectively increased, and the gas-liquid mass transfer rate is improved.

The primary problem of the reactive rectifying tower is how to improve the mass transfer between substances in the tower and the reaction rate. Currently, the most widely used method for large refineries and chemical plants is to add solid packing to the trays to increase mass transfer between the materials; catalyst is added to the trays to increase the chemical reaction rate. However, the existing mode simply stacks the filler or the catalyst on the tower plate, is limited by tower height and logistics conditions, has limited improvement range of mass transfer and reaction efficiency, and increases the number of the tower plates and increases the production cost.

The existing methods for improving the mass transfer reaction efficiency of the single-layer tower plates are many, but most methods are that filler layers and catalyst layers are arranged in a staggered manner, according to the liquid flow direction, the distribution modes of the filler layers and the catalyst layers can be divided into longitudinal distribution and transverse distribution, liquid flows downwards from the upper layer tower plates, gas flows upwards from the lower layer tower plates and sequentially passes through each filler layer or catalyst layer, so that the synergistic effect of strengthening mass transfer and improving the reaction rate is realized. However, both distribution modes are limited by the single-layer tower height and the tower diameter, and the thickness of the filler or the catalyst and the number of staggered layers are limited. If the thickness of the filler or the catalyst is increased, the number of staggered layers is reduced, and the synergistic effect of mass transfer reaction is poor; if the number of staggered layers is increased, the construction cost is increased, and the operation difficulty is increased.

Therefore, a reaction rectifying tower with higher mass transfer reaction efficiency on a single-layer tower plate is needed, and the reaction rectifying tower is suitable for gas-liquid-solid reaction with gas-liquid reverse contact.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art.

Disclosure of Invention

The invention aims to provide a reaction rectifying tower suitable for gas-liquid-solid reaction, which can effectively improve the mass transfer reaction efficiency through the action of centrifugal rotational flow.

To achieve the above object, according to a first aspect of the present invention, there is provided a reactive distillation column suitable for a gas-liquid-solid reaction of a gas-liquid countercurrent contact, comprising: a sieve plate fixed on the inner wall of the reactive distillation column, allowing the ascending gas phase to pass through; the basket body is positioned above the screen plate and used for supporting the filling materials and the catalysts which are transversely staggered; a liquid dropping unit located above the housing for providing a dropped liquid phase; and the impeller is positioned in the space between the sieve plate and the basket body and is used for generating centrifugal swirl effect when gas and liquid reversely contact with the filler and the catalyst.

In the above-described aspect, the impeller may be driven to rotate by a central shaft that is provided in the center of the reactive distillation column and penetrates the reactive distillation column.

Further, in the above technical solution, the liquid dropping unit may include: the inlet of the liquid-falling connection transverse pipe is arranged on one side of the inner wall of the tower, and the outlet of the liquid-falling connection transverse pipe is communicated with the inlet of the liquid-falling vertical pipe; and the liquid drop vertical pipe is penetrated by the central shaft to form an annular space, the annular space extends vertically along the central shaft, and the liquid phase descends along the annular space after entering from the inlet of the liquid drop connecting transverse pipe.

Further, in the above technical scheme, the part of the central shaft in the liquid drop vertical pipe is provided with external threads for forming a spiral drop effect of liquid phase in the annular space in the liquid drop process.

Furthermore, in the above technical scheme, the outlet of the liquid drop standpipe can be designed into a gradual expansion structure, and the spirally-descending liquid phase forms a cyclone effect at the outlet of the liquid drop standpipe.

Further, in the above technical solution, the outlet of the liquid drop standpipe is located below the liquid level, and the swirling flow agitates the liquid phase located above the basket.

Further, in the above technical scheme, the basket body can be fixed on the inner wall of the tower, the basket body can be divided into a plurality of areas, the plurality of areas can be sector areas which are uniformly arranged at intervals along the circumferential direction, and the adjacent sector areas are respectively filled with the filler and the catalyst. In the process of running the two gas-liquid material flows along the circumferential direction of the basket body under the action of centrifugal rotational flow, the two gas-liquid material flows can sequentially pass through each sector area to form an alternating process of reinforcing mass transfer of the filler to the gas-liquid and accelerating reaction of the catalyst to the gas-liquid.

In the above technical scheme, the casing may be divided into a plurality of regions, and the plurality of regions may be annular regions arranged at intervals along the radial direction, and adjacent annular regions are respectively filled with the filler and the catalyst. In the radial running process of the gas-liquid two-stream fluid along the basket body under the action of centrifugal rotational flow, the gas-liquid two-stream fluid can sequentially pass through each annular region to form an alternating process of reinforced mass transfer of the filler to the gas-liquid and accelerated reaction of the catalyst to the gas-liquid.

Furthermore, in the above technical scheme, one end of the central shaft is arranged outside the reactive rectifying tower in a penetrating way and is connected with the motor, the motor can be a forward and reverse rotating motor, and when the motor reversely rotates, the impeller drives the liquid phase to reversely flow and reversely impact the filler and the catalyst to form stirring.

Further, in the technical scheme, when the rotating speed of the impeller or the gas-liquid density difference is lower than a threshold value, the diameters of the air holes on the sieve plate are consistent and are uniformly arranged at intervals; when the rotating speed of the impeller or the gas-liquid density difference is higher than a threshold value, the size and the number of the air holes on the sieve plate are gradually increased outwards along the radial direction.

Further, in the above technical scheme, the sieve plate, the basket body, the liquid dropping unit and the impeller form a gas-liquid mass transfer reaction unit, and one or more gas-liquid mass transfer reaction units can be arranged in the reaction rectifying tower.

Compared with the prior art, the invention has the following beneficial effects:

1) According to the invention, spiral ascending air flow can be formed through rotation of the impeller, meanwhile, the impeller is arranged at a position close to the lower part of the basket body, a centrifugal swirl effect can be generated when gas and liquid are in reverse contact in the filler and the catalyst, the gas and the liquid can stay in the filler and the catalyst for a long time and dynamically move in the circumferential direction and the radial direction in the basket body, when the gas and the liquid run in a filler gap, the gas and liquid mass transfer efficiency can be effectively enhanced, and when the gas and the liquid run in a catalyst gap, the gas and liquid reaction efficiency can be effectively improved;

2) According to the invention, the outlet of the liquid drop vertical pipe is arranged below the liquid level, so that on one hand, ascending gas phase can be prevented from entering the liquid drop vertical pipe, and on the other hand, the accumulated liquid phase can be stirred in the same direction through rotational flow at the outlet of the vertical pipe, so that the liquid phase enters the basket body below in a spiral state, the retention time of the liquid phase in the filler and the catalyst of the basket body is longer, and the liquid phase is matched with the gas-liquid centrifugal rotational flow effect generated by the impeller, so that the gas-liquid mass transfer reaction efficiency can be further improved;

3) The basket body adopts a sector area arrangement mode, and two gas-liquid material flows can sequentially pass through each sector area in the circumferential running process of the basket body under the action of centrifugal rotational flow to form an alternating process of reinforced mass transfer of filler to gas-liquid and accelerated reaction of catalyst to gas-liquid, so that efficient mass transfer and reaction between gas and liquid are realized; by adopting the arrangement mode of the annular areas, in the radial running process of the gas-liquid two-flow fluid along the basket body under the action of centrifugal rotational flow, the gas-liquid two-flow fluid sequentially passes through each annular area, so that the alternating process of the reinforced mass transfer of the filler to the gas-liquid and the acceleration reaction of the catalyst to the gas-liquid can be formed, and the efficient mass transfer and reaction between the gas-liquid can be realized;

4) According to the invention, the design of the air holes on the sieve plate can adopt a mode that the diameter of the ruler and the number gradually increase outwards along the radial direction, when the rotating speed of the impeller is high or the density difference of gas-liquid reactants is large, the gas-liquid transverse layering condition in the centrifugal rotational flow process can be effectively avoided by adopting the design mode, the reduction of the gas-liquid contact area is avoided, and the gas-liquid mass transfer reaction is influenced;

5) The invention adopts the positive and negative rotation motor to drive the impeller, and can drive the fluid to reversely flow by changing the rotation direction of the impeller, thereby realizing the reverse impact on the filling material and forming stirring, thereby effectively using the deep material in the basket body, furthest improving the mass transfer reaction efficiency, delaying the service life of the filling material, reducing the replacement period and reducing the production cost;

6) The reaction rectifying tower can combine centrifugal rotational flow with filler reinforced mass transfer and catalyst acceleration reaction, can effectively improve the mass transfer reaction efficiency in a single-layer sieve plate, improve the reaction conversion rate in the reaction rectifying tower and save the production cost; the synergistic effect of the filler mass transfer and the catalytic reaction can be improved, the flexibility requirements of different reaction conditions and product requirements on the reaction rectifying tower are met, the reaction rectifying tower is simpler to adjust and reform, and the applicability is wider; and the structure is simple, and the operation is convenient.

The foregoing description is only an overview of the present invention, and it is to be understood that it is intended to provide a more clear understanding of the technical means of the present invention and to enable the technical means to be carried out in accordance with the contents of the specification, while at the same time providing a more complete understanding of the above and other objects, features and advantages of the present invention, and one or more preferred embodiments thereof are set forth below, together with the detailed description given below, along with the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of the overall structure of a reactive distillation column according to the present invention.

FIG. 2 is a schematic diagram showing the internal structure of the reactive distillation column of the present invention.

Fig. 3 is a schematic top view of one embodiment of a screen plate in the reactive distillation column of the present invention (while showing the top view structure of the liquid-lowering unit).

Fig. 4 is a schematic top view of another embodiment of the sieve plate in the reactive distillation column of the present invention (while showing the top view structure of the liquid-dropping unit).

FIG. 5-A is a schematic view of a first embodiment of the sector-shaped partition of the housing in the reactive distillation column of the present invention.

FIG. 5-B is a schematic view of a second embodiment of the sector-shaped partition of the housing in the reactive distillation column of the present invention.

FIG. 5-C is a schematic view of a first embodiment of the annular partition of the housing in the reactive distillation column of the present invention.

FIG. 5-D is a schematic view of a second embodiment of the annular partition of the housing in the reactive distillation column of the present invention.

The main reference numerals illustrate:

the device comprises a 1-reaction rectifying tower, 11-sieve plates, 111-air holes, 12-basket bodies, 121-packing, 122-catalysts, 13-liquid dropping units, 131-liquid dropping connection transverse pipes, 1310-transverse pipe inlets, 132-liquid dropping vertical pipes, 1320-vertical pipe outlets, 14-impellers, 140-central shafts, 2-liquid phase inlets, 3-gas phase inlets, 4-gas phase outlets, 5-liquid phase outlets and 6-motors.

Detailed Description

The following detailed description of embodiments of the invention is, therefore, to be taken in conjunction with the accompanying drawings, and it is to be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the term "comprise" or variations thereof such as "comprises" or "comprising", etc. will be understood to include the stated element or component without excluding other elements or other components.

Spatially relative terms, such as "below," "beneath," "lower," "above," "upper," and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element's or feature's in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the article in use or operation in addition to the orientation depicted in the figures. For example, if the article in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the elements or features. Thus, the exemplary term "below" may encompass both a direction of below and a direction of above. The article may have other orientations (rotated 90 degrees or other orientations) and the spatially relative descriptors used herein interpreted accordingly.

The terms "first," "second," and the like herein are used for distinguishing between two different elements or regions and are not intended to limit a particular position or relative relationship. In other words, in some embodiments, the terms "first," "second," etc. may also be interchanged with one another.

As shown in fig. 1, the invention provides a reactive rectifying tower 1, which is suitable for gas-liquid-solid reaction of gas-liquid reverse contact. The invention carries out centrifugal rotational flow reinforced mass transfer reaction rectification through the reaction rectifying tower, and the reaction rectifying process aiming at different systems is as follows: the low boiling point reactant (i.e. gas phase feed) enters from the gas phase inlet 3 at the lower part of the tower body, moves upwards from the lower part of the tower in a gas phase form, the high boiling point reactant (i.e. liquid phase feed) enters from the liquid phase inlet 2 at the upper part of the tower body, flows downwards from the upper part of the tower in a liquid form, and the two reactants are in countercurrent contact to achieve the aim of mass transfer reaction. The reaction product and the reaction by-product may be discharged from the top gas phase outlet 4 or the bottom liquid phase outlet 5, respectively, according to the difference in boiling points thereof. In order to improve the mass transfer and reaction efficiency of the gas-liquid, a filler and a catalyst are arranged on the gas-liquid running path in the reactive rectifying tower 1. The column body of the reactive rectifying column is a cylindrical closed space, besides the gas-liquid phase inlet and outlet, a condensation reflux inlet, a reboiling reflux inlet, a side outlet and a side inlet (not shown in the figure) can be arranged according to actual requirements. The present invention drives the impeller 14 to rotate through a central shaft 140 (refer to fig. 2) located at the center of the tower body and penetrating the tower body, thereby generating the centrifugal swirling effect of the present invention. The lower end of the central shaft 140 passes through the tower body and is connected with the motor 6 to provide rotary power for the impeller 14.

As further shown in fig. 2, the reactive distillation column 1 of the present invention includes a screen plate 11, a housing 12, a liquid-dropping unit 13, and an impeller 14. Wherein the screen plate 11 is fixed to the inner wall of the reactive distillation column 1, allowing the ascending gas phase to pass through. The basket 12 is located above the screen plate 11 and is used for supporting the filler 121 and the catalyst 122 which are transversely staggered. A liquid-lowering unit 13 is located above the housing 12 for providing a lowered liquid phase. The impeller 14 is located in the space between the screen plate 11 and the housing 12 for generating a centrifugal swirling effect when the gas-liquid contacts reversely the packing and the catalyst.

As further shown in fig. 2, the screen plate 11, the housing 12, the liquid dropping unit 13, and the impeller 14 constitute one gas-liquid mass transfer reaction unit, and in the reactive distillation column 1 of the present invention, one or more of these gas-liquid mass transfer reaction units may be provided. If a plurality of the modules are arranged, the modules are arranged in layers up and down.

As further shown in fig. 3, the sieve plate 11 may be provided with uniformly distributed air holes 111, the air holes 111 allow the ascending gas phase to enter the sieve plate through the air holes, and the gas phase is dispersed into a plurality of continuous gas flows or bubble flows by the air holes 111 on the sieve plate when flowing through the sieve plate 11 in the upward flowing process, so that the ascending gas is uniformly dispersed above the sieve plate, the gas-liquid contact area is increased, and the gas-liquid mass transfer reaction efficiency is improved. The liquid phase cannot descend through the air holes 111 due to the pressure of the gas phase rising at the air holes. The screen plate 11 may be designed in an umbrella shape (refer to fig. 2) so that the upper liquid phase can be rapidly collected at the outer edge of the screen plate, and the liquid phase is introduced into the liquid dropping unit 13 through only the cross pipe inlet 1310 at one side of the edge of the screen plate 11. The distribution and size of the openings of the air holes 111 may be determined according to the rotation speed of the impeller 14, the difference in gas-liquid density, the structure of the casing 12, the flow rate of the gas, and the like. The center of the screen plate is provided with a center hole for penetrating the center shaft 140, and the center hole and the center shaft 140 are subjected to shaft seal treatment.

Further, as shown in fig. 2, since the impeller 14 is located in the space between the screen plate 11 and the housing 12, the gas phase rising from the air holes 111 of the screen plate is agitated by the impeller 14 to form a spiral rising air flow, meanwhile, the impeller 14 is arranged at a position relatively close below the housing 12, and the rotation of the impeller can generate centrifugal swirl effect when the gas and the liquid are reversely contacted in the filler 121 and the catalyst 122, the gas and the liquid can stay in the filler and the catalyst for a long time, and the stay is dynamic, namely, the gas and the liquid can also form circumferential and radial movement in the housing, so that the gas and liquid mass transfer efficiency can be effectively enhanced when the gas and the liquid are operated in the filler gap, and the gas and liquid reaction efficiency can be effectively improved when the gas and the liquid are operated in the catalyst gap.

As further shown in fig. 2, the downcomer unit may include, preferably but not limited to, a downcomer connecting cross pipe 131 and a downcomer standpipe 132. The inlet 1310 of the horizontal drop tube 131 is disposed on one side of the inner wall of the tower, and the outlet communicates with the inlet of the drop stack 132. The drop stack 132 is intersected by the central axis 140 to form an annular space that extends vertically along the central axis 140, and liquid phase may flow laterally through the drop connection cross tube after entering through the inlet 1310 of the drop connection cross tube, and then descend along the annular space. Preferably, but not by way of limitation, the portion of the central shaft 140 within the drop stack 132 is provided with external threads (not shown) that, as the central shaft 140 rotates, may be used to create a helical drop effect of the liquid phase within the annular space during the drop process. Further, the outlet 1320 of the drop stack 132 is a gradual expansion structure, and the spirally descending liquid phase may form a swirling effect at the outlet of the drop stack 1320. Since the liquid phase can be accumulated above the basket 12, the outlet 1320 of the liquid drop standpipe 132 is arranged below the liquid level, so that on one hand, the ascending gas phase can be prevented from entering the liquid drop standpipe 132, and on the other hand, the accumulated liquid phase can be stirred in the same direction by the rotational flow of the standpipe outlet 1320, so that the liquid phase enters the basket 12 below in a spiral state, the residence time of the liquid phase in the filler and the catalyst of the basket is longer, and the gas-liquid mass transfer reaction efficiency can be further improved by being matched with the gas-liquid centrifugal rotational flow effect generated by the impeller 14.

As further shown in fig. 5-a and 5-B, the housing 12 is fixed to the tower inner wall, and the housing 12 is divided into a plurality of regions, preferably but not limited to, sector-shaped regions uniformly spaced circumferentially, adjacent sector-shaped regions being filled with the packing 121 and the catalyst 122, respectively. The first embodiment in fig. 5-a provides four sectors and the second embodiment in fig. 5-B provides eight sectors. By adopting the arrangement mode of the sector areas, two gas-liquid material flows can sequentially pass through each sector area in the circumferential running process of the basket body 12 under the action of centrifugal rotational flow to form the alternating process of reinforced mass transfer of filler to gas-liquid and acceleration reaction of catalyst to gas-liquid, namely rotational flow fluid can sequentially, repeatedly and circularly flow through the sector filler area and the catalyst area in the basket body 12, thereby realizing efficient mass transfer and reaction between gas and liquid.

As further shown in fig. 5-C and 5-D, the separate plurality of zones may also be, preferably but not limited to, annular zones disposed radially apart, adjacent annular zones being filled with the packing 121 and catalyst 122, respectively. The first embodiment in fig. 5-C provides four annular zones and the second embodiment in fig. 5-D provides two annular zones. By adopting the arrangement mode of the annular areas, in the radial running process of the gas-liquid two-flow fluid along the basket 12 under the action of centrifugal rotational flow, the gas-liquid two-flow fluid sequentially passes through each annular area, and also can form the alternating process of the reinforced mass transfer of the filler to the gas-liquid and the acceleration reaction of the catalyst to the gas-liquid, namely the rotational flow fluid can sequentially flow through the annular filler area and the catalyst area in the basket 12, thereby realizing the efficient mass transfer and reaction between the gas and the liquid.

Further, the motor 6 for driving the central shaft 140 preferably adopts a forward and reverse rotation motor, and in an initial running state, the motor is always in a forward rotation state, the rotation of the impeller 14 enables gas and liquid to form centrifugal rotational flow, and under the action of the centrifugal rotational flow, the gas and liquid generate circumferential and radial motions in the filler and the catalyst of the basket 12, so that the alternating progress of strengthening gas and liquid mass transfer and accelerating reaction is realized. When operated for a period of time, the packing and/or catalyst may be affected by the liquid level (i.e., the fluid inflow surface) by trace impurities, etc., reducing packing and catalyst activity, while the material or catalyst not being inside the liquid level or packing material may also retain higher activity. At this time, the motor 6 is reversed, and the fluid can be driven to reversely flow by changing the rotation direction of the impeller, so that the reverse impact on the filling material is realized, and stirring is formed, thereby effectively utilizing the deep material in the basket body, furthest improving the mass transfer reaction efficiency, delaying the service life of the filling material, reducing the period of changing the agent and reducing the production cost.

Further researches of the inventors find that when the impeller 14 of the invention is adopted to generate centrifugal rotational flow, and the rotational speed of the impeller is high or the density difference of gas-liquid reactants is large, the gas-liquid lateral layering condition can occur in the centrifugal rotational flow process, so that the gas-liquid contact area is reduced, and the gas-liquid mass transfer reaction is affected. At this time, the rotation speed of the impeller can be properly reduced, so that the gas and the liquid are uniformly dispersed, and layering is prevented. I.e. when the impeller rotation speed or the gas-liquid density difference is lower than a certain threshold value, the air holes 111 on the sieve plate 11 can be uniformly arranged at intervals (i.e. in the manner shown in fig. 3). If the impeller is required to keep high rotation speed or the density difference of the gas-liquid reactants is large, the size of the openings at the edge of the sieve plate 11 can be increased, the number of the openings is increased, the number of the openings at the center is relatively small, and the size is small, so that most of the gas flows from the edge of the sieve plate 11, the gas phase flows towards the center under the centrifugal action, and the liquid phase flows towards the edge under the centrifugal action, so that the gas-liquid is transversely countercurrent on the sieve plate, and the mass transfer reaction efficiency is improved. That is, when the impeller rotation speed or the gas-liquid density difference is higher than a certain threshold value, the design of the air holes 111 on the sieve plate 11 can adopt a mode that the size diameter and the number gradually increase outwards along the radial direction.

The reactive rectifying tower can calculate the reaction rate and the mass transfer rate according to the conditions of the reactant property, the filler property, the catalyst property, the fluid flow rate, the temperature, the reactive rectifying tower size and the like in the actual operation process, so that the mass transfer reaction efficiency in a single-layer sieve plate is improved to the greatest extent by designing the rotating speed of an impeller, the partition structure of a basket filler and the catalyst and the like. The reaction rectifying tower can combine centrifugal rotational flow with filler reinforced mass transfer and catalyst acceleration reaction, can effectively improve the mass transfer reaction efficiency in a single-layer sieve plate, improve the reaction conversion rate in the reaction rectifying tower and save the production cost. The invention improves the synergistic effect of the filler mass transfer and the catalytic reaction, meets the flexibility requirements of different reaction conditions and product requirements on the reaction rectifying tower, and has simpler regulation and transformation and wider applicability. The reactive rectifying tower has the advantages of simple structure and convenient operation.

Example 1

By adopting the reactive rectifying tower, the dimethyl maleate (DMM) is generated by the reaction of the monomethyl maleate (MMM) and the methanol. The liquid reactant MMM and methanol are mixed according to a certain proportion, then enter the reactive rectifying tower 1 through the liquid phase inlet 2, and the reactant gaseous methanol enters the reactive rectifying tower 1 through the gas phase inlet 3. The MMM and methanol mixture flows from top to bottom in liquid state, and the gaseous methanol flows from bottom to top, so that a gas-liquid countercurrent mass transfer reaction process is formed in the whole tower.

In the embodiment, a plurality of gas-liquid mass transfer reaction units are adopted, in a certain layer of screen plate 11 of the reaction rectifying tower, liquid reactants (MMM and methanol) and products (DMM and water) flowing in from an upper layer of screen plate through a liquid dropping unit 13 enter a liquid phase layer of the gas-liquid mass transfer reaction unit, gaseous reactants and products flowing in from a lower layer of screen plate 11 are dispersed into the liquid phase layer of the gas-liquid mass transfer reaction unit, and the liquid and gaseous reactants and products do centrifugal rotational flow movement in a basket 12 under the action of an impeller 14 and are circularly and alternately contacted with a filler 121 and a catalyst 122 in the basket 12, so that unreacted MMM and methanol in the layer further react to generate DMM and water. Finally, the liquid-phase DMM with higher purity is obtained at the liquid-phase outlet at the bottom of the tower, and gaseous methanol and water vapor are discharged at the top of the tower and are accompanied by a certain amount of gaseous DMM.

Example 2

After the reaction rectifying tower is adopted to react the methyl maleate (MMM) with the methanol to generate the dimethyl maleate (DMM) for a period of time, the yield of the tower bottom product is obviously reduced, and the catalyst and the filler are judged to be deactivated. At this time, the impeller 14 is reversely rotated according to the original rotation speed, so that the liquid flow in each layer of gas-liquid mass transfer reaction unit is turned, and the use efficiency of the catalyst and the filler which are not used or less used in the deep part of each layer of tower is improved.

The problem of a short bottom yield decrease occurs at the initial stage of the inversion of the impeller 14, because the instantaneous diversion causes a short disappearance of the centrifugal swirling action of the liquid flow in each layer of the tower, and in this process, the contact time between the liquid flow in each layer of the tower and the filling material in the basket 12 becomes short, the synergistic effect of the mass transfer reaction becomes poor, and the bottom product yield becomes short. However, when the reverse rotation is stable, the tower bottom yield gradually rises and approaches the initial running level, so that the service lives of the catalyst and the filler are prolonged, and the catalyst replacement period and the production cost are reduced.

The foregoing descriptions of specific exemplary embodiments of the present invention are presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application to thereby enable one skilled in the art to make and utilize the invention in various exemplary embodiments and with various modifications as are suited to the particular use contemplated. Any simple modifications, equivalent variations and modifications of the above-described exemplary embodiments should fall within the scope of the present invention.

Claims (13)

1. A reactive distillation column, characterized in that it is suitable for gas-liquid-solid reaction of gas-liquid reverse contact, comprising:

a sieve plate fixed on the inner wall of the reactive distillation column, allowing the ascending gas phase to pass through;

the basket body is positioned above the sieve plate and used for supporting the filling materials and the catalysts which are transversely staggered;

a liquid dropping unit located above the housing for providing a dropped liquid phase;

and the impeller is positioned in the space between the sieve plate and the basket body and is used for generating centrifugal swirl effect when gas and liquid reversely contact with the filler and the catalyst.

2. The reactive distillation column of claim 1, wherein the impeller is rotatably driven by a central shaft disposed centrally in the reactive distillation column and extending therethrough.

3. The reactive distillation column of claim 2, wherein the liquid reduction unit comprises:

the inlet of the liquid-falling connection transverse pipe is arranged on one side of the inner wall of the tower, and the outlet of the liquid-falling connection transverse pipe is communicated with the inlet of the liquid-falling vertical pipe;

and the liquid drop vertical pipe is penetrated by the central shaft to form an annular space, the annular space extends vertically along the central shaft, and the liquid phase descends along the annular space after entering from the inlet of the liquid drop connection transverse pipe.

4. A reactive distillation column according to claim 3 wherein the portion of the central shaft within the downcomer standpipe is provided with external screw threads for forming a helical descent effect of the liquid phase within the annular space during the downcomer.

5. The reactive distillation column of claim 4, wherein the outlet of the downcomer standpipe is of a gradual expansion configuration, and the helically descending liquid phase forms a swirling effect at the outlet of the downcomer standpipe.

6. The reactive distillation column of claim 5, wherein the outlet of the downcomer standpipe is below the liquid level and the cyclone agitates the liquid phase above the basket.

7. The reactive distillation column of claim 1, wherein the housing is fixed to an inner wall of the column, the housing being divided into a plurality of regions, the plurality of regions being sector-shaped regions arranged at uniform intervals in a circumferential direction, adjacent sector-shaped regions being filled with the packing and the catalyst, respectively.

8. The reactive distillation column of claim 7, wherein the gas-liquid two streams sequentially pass through each of the sector-shaped areas during the process of running along the circumference of the basket body under the action of centrifugal rotational flow, thereby forming an alternating process of enhanced mass transfer of the filler to the gas and accelerated reaction of the catalyst to the gas and liquid.

9. The reactive distillation column of claim 1, wherein the housing is divided into a plurality of regions, the plurality of regions being annular regions disposed at radial intervals, adjacent annular regions being filled with the packing and catalyst, respectively.

10. The reactive distillation column of claim 9, wherein the gas-liquid two streams sequentially pass through each annular region during radial operation of the basket under the action of centrifugal rotational flow to form an alternating process of enhanced mass transfer of the filler to the gas-liquid and accelerated reaction of the catalyst to the gas-liquid.

11. The reactive distillation column of claim 2, wherein one end of the central shaft is penetrated outside the reactive distillation column and is connected with a motor, the motor is a counter-rotating motor, and when the motor rotates reversely, the impeller drives the liquid phase to flow reversely and carries out reverse impact on the packing and the catalyst to form stirring.

12. The reactive distillation column of claim 1, wherein when the impeller speed or gas-liquid density difference is below a threshold, the pore sizes on the screen plates are uniform and evenly spaced; when the rotating speed of the impeller or the gas-liquid density difference is higher than a threshold value, the size and the number of the air holes on the sieve plate are gradually increased outwards along the radial direction.

13. The reactive distillation column of claim 1, wherein the screen, housing, liquid-dropping unit, and impeller form a gas-liquid mass transfer reaction unit, and one or more of the gas-liquid mass transfer reaction units are provided in the reactive distillation column.