CN116236992A

CN116236992A - High-efficient microchannel reactor

Info

Publication number: CN116236992A
Application number: CN202310265713.XA
Authority: CN
Inventors: 岳金彩; 秦利涛; 杨安明; 周东健; 孔令启; 杨霞; 程华农
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2023-03-20
Filing date: 2023-03-20
Publication date: 2023-06-09

Abstract

The invention discloses a high-efficiency microchannel reactor, which comprises a feed channel unit and a plurality of reaction channel units, wherein two adjacent reaction channel units are connected through a reaction discharge channel; each reaction channel unit consists of two branch reaction channels; the feeding channel unit comprises 3 or more than 3 feeding ports, the rear of each feeding port is connected with a feeding channel, all the feeding channels are connected with a feeding main channel, and two adjacent feeding ports are filled with two different reaction materials; the bottoms of the feeding main channel and the reaction discharging channel are distributed with flow guiding structures, the flow guiding structures comprise an oblique diagonal line formed at the bottom of the feeding main channel, and the bottoms of the two sides of the oblique diagonal line are gradually raised and gradually lowered. The reactor disclosed by the invention can rotate and stretch the material contact surface by about 90 degrees within a certain Re number range, so that the contact area is further increased, the mass transfer distance is further reduced, and the mixing effect is improved.

Description

High-efficient microchannel reactor

Technical Field

The invention relates to the technical field of micro-reactors, in particular to a high-efficiency micro-channel reactor.

Background

The microchannel reactor has the advantages of continuous operation, easily-controlled and stable parameters, simple operation, high safety and the like, and is more and more widely paid attention to the fields of chemical industry, medicine, material synthesis and the like. The characteristic size of the micro-channel is small, the Re number of the fluid flow is small, the turbulent state is difficult to reach, the mixing speed of the two fluids is largely controlled by molecular diffusion on the fluid contact surface, especially when the flow speed is low, and therefore, the increase of the contact area of the two fluids becomes an important means for enhancing the mixing.

The two fluid multilayer superposition is an effective method for increasing the contact area, and the realization of the fluid multilayer superposition in a channel is generally required to be realized in a branch-and-merge channel with a 3D structure, the channel processing is required to adopt 3D printing, the application range is limited, and the application range is difficult to be applied in the process industry from the published research report.

Local mixing structures such as sharp corners of the channel, built-in blocking structures and the like are arranged in the channel, and when fluid flows, the blocking structures are blocked to generate a velocity component perpendicular to the flowing direction so as to form vortex, thus achieving the effects of increasing the contact area and enhancing the mixing, but the blocking structures can lead to larger pressure drop, also can lead to wider material residence time distribution, and are disadvantageous to the improvement of the product yield of certain reactions.

The flow of fluid in the tortuous path creates dean vortices perpendicular to the flow direction, resulting in increased material contact area. Generally, the large curvature of the channel and the high flow rate of the material are beneficial to improving the dean vortex strength and improving the mixing strength, but the pressure drop is also increased. The mixing effect of the curved channels with different shapes is not consistent on the premise that the length and the pressure drop are basically consistent.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-efficiency microchannel reactor so as to achieve the purpose of improving the mixing efficiency under the condition that the pressure drop is not increased basically, especially under the condition of low Re number.

In order to achieve the above purpose, the technical scheme of the invention is as follows:

the high-efficiency microchannel reactor comprises a feeding channel unit and a plurality of reaction channel units, wherein two adjacent reaction channel units are connected through a reaction discharging channel, the feeding channel unit is connected with a first reaction channel unit through a feeding total channel, and a last reaction channel unit is connected with a microchannel reactor outlet through a reaction discharging channel; each reaction channel unit consists of two branch reaction channels, and the two branch reaction channels are connected with a reaction discharge channel after being converged;

the feeding channel unit comprises 3 or more than 3 feeding inlets which are arranged in sequence, one feeding channel is connected behind each feeding inlet, all the feeding channels are connected with a feeding total channel, and two adjacent feeding inlets are filled with two different reaction materials;

the bottom of the feeding main channel and the bottom of the reaction discharging channel are distributed with flow guiding structures, the flow guiding structures comprise an oblique diagonal line formed at the bottom of the feeding main channel, and the bottom surfaces positioned at two sides of the oblique diagonal line are gradually raised and gradually lowered.

In the scheme, the feeding channels of other feeding inlets except the last feeding inlet are divided into two feeding branch channels, the two feeding branch channels are distributed on two axial sides of the feeding channel, and after two adjacent feeding branch channels on the same side are converged into a first feeding main channel, the two adjacent feeding branch channels are directly converged with the feeding channel of the last feeding inlet into a feeding main channel, or after the two adjacent feeding branch channels are converged with the next adjacent feeding branch channel into an N feeding main channel, N is more than or equal to 2, and then the two adjacent feeding branch channels are converged with the feeding channel of the last feeding inlet into the feeding main channel.

In the scheme, 3-7 guide structures are used as a group and distributed at the bottoms of the feeding main channel and the reaction discharging channel.

In the scheme, the depth of the first feeding main channel after the two feeding branch channels are converged is unchanged, and the width is smaller than or equal to the sum of the widths of the two feeding branch channels and is larger than or equal to the width of the single feeding branch channel.

In the scheme, the feeding channel of the last feeding port is converged with the two first feeding main channels or the two Nth feeding main channels after being converged at two sides to form a feeding total channel, the depth of the feeding total channel is consistent with that of the first feeding main channel or the Nth feeding main channel, the feeding total channel is a rectangular channel, and the width of the feeding total channel is 1.5-6 times of the depth of the feeding total channel.

In the scheme, each branch reaction channel is formed by connecting three semi-elliptical channels with different lengths end to end, the depth of each semi-elliptical channel is consistent with that of the feeding total channel, and the width of each semi-elliptical channel is more than or equal to half of that of the feeding total channel and less than or equal to that of the feeding total channel.

In the above scheme, the depth and width of the reaction discharging channel are consistent with those of the feeding total channel.

Preferably, the ratio of the short major axes of the semi-elliptical channels is 0.3-0.7.

More preferably, the ratio of the short and long axes of the semi-elliptical channels is 0.5-0.6, the mixing efficiency is highest at the more preferred short and long axes ratio, the improvement rate is more than 20% compared with the circular channel in a certain Re number range, and the pressure drop is hardly changed.

Through the technical scheme, the high-efficiency microchannel reactor provided by the invention has the following beneficial effects:

1. according to the microchannel reactor disclosed by the invention, the superposition combination of different materials is formed in the feeding channel unit, the contact area of the materials is increased by times, the mixing effect can be effectively improved even under the condition that vortex or dean vortex is difficult to form or the strength is low, and the Re number application range of the microchannel reactor is enlarged.

2. The total feeding channel is a rectangular channel with the width being 1.5-6 times of the depth, and the channel increases the specific surface area and is beneficial to temperature control.

3. The invention arranges a diversion structure instead of a blocking structure in the feed main channel and the reaction discharge channel, and has smaller pressure drop. The flow guiding structure enables the material flow to rotate, and in a certain Re number range, the material contact surface can rotate and stretch by 90 degrees, the contact area is further increased, the mass transfer distance is further reduced, and the mixing effect is improved.

4. The branched reaction channel formed by combining the semi-elliptic channels can form periodic strengthening and maintaining of dean vortex under the premise of basically unchanged pressure drop, and the mixing efficiency is improved by more than 20 percent compared with a circular channel with the same length within a certain Re number range.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a schematic diagram of a high efficiency microchannel reactor according to an embodiment of the present invention;

FIG. 2 is an enlarged schematic view of a feed channel unit;

FIG. 3 is a schematic view of a flow guiding structure;

FIG. 4 is a perspective view of a flow guiding structure; (a) is bottom-down; (b) bottom surface facing upward;

FIG. 5 is a graph showing the concentration distribution of the contact surface of two materials on the section of the inlet and outlet of the flow guiding structure; (a) at the inlet and (b) at the outlet;

FIG. 6 is an enlarged schematic view of a reaction channel unit.

In the figure, A, a feed channel unit; B. a reaction channel unit; 1. a first feed port; 2. a second feed inlet; 3. a third feed inlet; 4. a fourth feed inlet; 5. a reaction discharge channel; 6. a total feed channel; 7. a microchannel reactor outlet; 8. a first feed main channel; 9. a second feed main channel; 10. a flow guiding structure; 11. a feed channel; 12. a feed branch channel; 13. a first semi-ellipse; 14. a second semi-ellipse; 15. and a third semi-elliptical.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

The invention provides a high-efficiency microchannel reactor, which comprises a feed channel unit A and a plurality of reaction channel units B, wherein two adjacent reaction channel units B are connected through a reaction discharge channel 5, the feed channel unit A is connected with a first reaction channel unit B through a feed total channel 6, and a last reaction channel unit B is connected with a microchannel reactor outlet 7 through the reaction discharge channel 5.

The microchannel reactor provided by the invention is provided with at least three feed inlets, preferably four feed inlets. When designing a large-load microchannel reactor, the number of feed inlets can be preferably increased to 5 or more.

In this embodiment, the feed channel unit a includes 4 feed inlets arranged in sequence, and as shown in fig. 2, the 4 feed inlets are arranged in a straight line. The back of each feed inlet is connected with a feed channel 11, the feed channels 11 of other feed inlets except the fourth feed inlet 4 are divided into two feed branch channels 12, the two feed branch channels 12 are distributed on two axial sides of the feed channel 11, two adjacent feed branch channels 12 on the same side are converged into a first feed main channel 8 and then converged into a second feed main channel 9 with the next adjacent feed branch channel 12, and then converged into a feed main channel 6 with the feed channel 11 of the last feed inlet. The branch channels on the two sides are converged in a T-shaped mode in sequence, and the part C in fig. 2 is seen.

In this embodiment, the depth of the first feeding main channel 8 after the two feeding branch channels 12 are joined is constant, and the width is smaller than or equal to the sum of the widths of the two feeding branch channels 12 and is equal to or larger than the width of the single feeding branch channel 12. The reaction discharge channel 5 has a depth and width corresponding to those of the total feed channel 6.

The feeding channel 11 of the fourth feeding port 4 merges with the two second main feeding channels 9 after merging on both sides into a total feeding channel 6, the depth of the total feeding channel 6 is identical to the depth of the second main feeding channel 9, the total feeding channel 6 is a rectangular channel, and the width is 1.5-6 times, preferably 2-4 times, the depth of the total feeding channel 6. In this example, the width of the total feed channel was 2 times its depth.

Two adjacent feed inlets are filled with two different reaction materials, namely, one feed inlet is separated from the other feed inlet, and the same reaction materials are filled in. As shown in fig. 1, the first feed port 1 and the third feed port 3 are fed with one reaction material, and the second feed port 2 and the fourth feed port 4 are fed with the other reaction material.

The bottom of the feeding main channel 6 and the bottom of the reaction discharging channel 5 are respectively provided with 5 diversion structures 10, the enlarged diversion structures 10 are shown in fig. 3, the diversion structures 10 comprise a diagonal line 16 formed at the bottom of the feeding main channel 6, and the bottom surfaces positioned at two sides of the diagonal line gradually rise and gradually fall. The angle between the diagonal and the axis of the channel is 30-60 degrees, preferably 45 degrees. In order to more clearly show the

air guiding structure

10, 5 cross-sectional views a, b, c, d, e of the air guiding structure 10 perpendicular to the axial direction are also shown in fig. 3.

As can be seen from fig. 4 (a) and (b), the raised bottom surface configuration causes the material to flow through the flow directing structure to act like an impeller, causing the flow to rotate without a significant increase in pressure drop. The material contact surface can be twisted and stretched through the logistics rotation, the contact surface can be rotated by 90 degrees through 5 diversion structures under a certain Re number, and the stretching effect is better for a channel with a rectangular section, so that the mixing is facilitated.

Simulation of the mixing effect of water-water materials in the micro-channel was performed using FLUENT software, and FIG. 5 shows the concentration distribution of the two materials in the total feed channel 6 at the inlet and outlet cross sections of the flow guide structure 10 when Re is 50. As can be seen from FIG. 5 (a), the two materials at the inlet are arranged at intervals, and 6 contact surfaces are provided, which is generated by the unique feed mode of the present invention, and the contact area of the materials is increased by times. As can be seen in fig. 5 (b), the material is twisted and rotated after passing through the 5 guide structures 10, and the contact area of the material is further increased.

Each reaction channel unit B consists of two branch reaction channels, and the two branch reaction channels are connected with a reaction discharge channel 5 after being converged. As shown in fig. 6, each branched reaction channel is formed by connecting three semi-elliptical channels with different lengths end to end, the head end of a first semi-ellipse 13 is connected with a reaction discharge channel 5, the tail end is connected with a second semi-ellipse 14, and the tail end of a third semi-ellipse 15 is connected with a next reaction discharge channel 5. The minor-major axis ratio of the ellipse is 0.5. The depth of the semi-elliptical channel is consistent with that of the feeding total channel 6, and the width is more than or equal to half of the width of the feeding total channel 6 and less than or equal to the width of the feeding total channel 6.

Table 1 shows the mixing efficiency and pressure drop of two water streams at different Re numbers in the single branched reaction channel and the branched channel formed by three semicircles of the same length in the present example. It can be seen that the mixing efficiency using the semi-elliptical channel is improved by more than 20% over the semi-circular channel within a certain Re number range, while the pressure drop is almost the same.

TABLE 1 comparison of mixing effects of semi-circular channels and semi-elliptical channels

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. The high-efficiency microchannel reactor is characterized by comprising a feeding channel unit and a plurality of reaction channel units, wherein two adjacent reaction channel units are connected through a reaction discharging channel, the feeding channel unit is connected with a first reaction channel unit through a feeding total channel, and a last reaction channel unit is connected with a microchannel reactor outlet through a reaction discharging channel; each reaction channel unit consists of two branch reaction channels, and the two branch reaction channels are connected with a reaction discharge channel after being converged;

2. The efficient microchannel reactor according to claim 1, wherein the feed channels of the other feed inlets except the last feed inlet are divided into two feed branch channels, the two feed branch channels are distributed on two axial sides of the feed channel, and after the adjacent two feed branch channels on the same side are converged into a first feed main channel, the two feed branch channels are directly converged into a feed main channel with the feed channel of the last feed inlet, or after the two feed branch channels are converged into an Nth feed main channel with the next adjacent feed branch channel, N is more than or equal to 2, and then the two feed branch channels are converged into a feed main channel with the feed channel of the last feed inlet.

3. The efficient microchannel reactor according to claim 1, wherein the flow guiding structures are distributed in groups of 3-7 at the bottoms of the total feed channels and the reaction discharge channels.

4. The efficient microchannel reactor according to claim 2, wherein the depth of the first feed main channel after the two feed branch channels meet is constant, and the width is less than or equal to the sum of the widths of the two feed branch channels and greater than or equal to the width of a single feed branch channel.

5. The efficient microchannel reactor according to claim 2, wherein the feed channel of the last feed inlet merges with two first feed main channels or two nth feed main channels after merging on both sides into a feed total channel, the depth of the feed total channel is identical to the depth of the first feed main channel or the nth feed main channel, and the feed total channel is a rectangular channel with a width 1.5-6 times its own depth.

6. The efficient microchannel reactor according to claim 1, wherein each branched reaction channel is formed by connecting three semi-elliptical channels with different lengths end to end, the depth of the semi-elliptical channels is consistent with that of the total feed channel, and the width of the semi-elliptical channels is equal to or more than half of that of the total feed channel and equal to or less than that of the total feed channel.

7. The efficient microchannel reactor of claim 1 wherein the reaction take-off channels are of depth and width consistent with the total feed channels.

8. The efficient microchannel reactor according to claim 6, wherein the ratio of the short and long axes of the semi-elliptical channels is 0.3-0.7.

9. The efficient microchannel reactor according to claim 6, wherein the ratio of the short and long axes of the semi-elliptical channels is 0.5-0.6.