microreactor

Abstract

The present invention relates to a microreactor, comprising a plurality of mixing units connected in sequence along a longitudinal direction. Each mixing unit comprises an outer shell, in which a flow chamber is formed. The opposite ends of each mixing unit along the longitudinal direction respectively form an inlet and an outlet, which are both connected to the flow chamber. The mixing unit also comprises a first blocking portion arranged in the flow chamber, which is centrally arranged in the flow chamber in a transverse direction perpendicular to the longitudinal direction and is between the inlet and the outlet, so that the flow chamber forms a first forward channel, a second forward channel and a mixing area. The first forward channel and the second forward channel are connected to the mixing area. At the downstream end of the first forward channel and the second forward channel, the microreactor is also provided with an auxiliary guide portion extending protruding from the first side profile and the second side profile relative to each other but spaced apart.

Description

Technical Field

[0001] The invention relates to the technical field of micro-chemical engineering, in particular to a micro-reactor. Background Art

[0002] A microreactor is a micro device that can be used for chemical reactions or substance mixing and is made of a solid matrix using special micromachining technology. The "micro" in microreactor means that the channels of the process fluid are generally at the micron level, and there are also solutions that can reach the millimeter level.

[0003] Microreactors have the characteristics of small size, large specific surface area, high reaction efficiency and precise control. They have broad application prospects for applications involving violent exothermic reactions, reactions with unstable intermediates or products, rapid reactions with strict ratio requirements, high temperature and high pressure, etc., and are expected to become a revolutionary technology that is efficient and safe in the chemical industry.

[0004] Due to the small scale, laminar flow and significant interface effects of microreactors, their flow and transfer characteristics are very different from those of conventional reactors, and their design concepts are also different. At present, microreactors mainly use two methods of static mixing, which do not rely on external power, but only use channel structure design and fluid flow properties to complete the mixing of reactants. It has the characteristics of stability, simplicity and wide application range.

[0005] Figure 1 A kind of existing microreactor 100 is shown. This microreactor includes a plurality of mixing units connected in sequence. Each mixing unit has an outer contour 101 that is an arc as a whole, and in particular, its side portion is a complete arc contour, and an inlet and an outlet are formed at the opposite ends of the outer contour. The outlet 102 of a single mixing unit forms an arc-shaped necking, so that the cross section of the outlet gradually decreases along the fluid flow direction. In addition, the outlet of a single mixing unit is completely embedded or buried in the inlet of the subsequent adjacent mixing unit, so that the two mixing units are closely connected and the profile has a certain overlap. In addition, an arc-shaped first blocking portion 103 and a circular second blocking portion 104 are also provided in a single mixing unit, and the second blocking portion 104 is closer to the outlet of the mixing unit relative to the first blocking portion 103. Thus, when the fluid enters the subsequent adjacent mixing unit through the outlet 102 of the previous mixing unit, it will impact on the first blocking portion 103, then flow to the two sides to split, and finally flow to the outlet of the mixing unit. The second barrier 104 forms a “retention zone” at its upstream to prevent the sediment in the fluid from continuing to flow downstream.

[0006] In the microreactor, the fluid easily forms eddies inside the first barrier 103, thereby prolonging the residence time of the fluid. This will cause the pressure drop of the fluid passing through the microreactor 100 to be very large. Figure 1As shown, the distance between the outer side of the first blocking portion 103 and the outer contour 101 gradually increases along the fluid flow direction. Therefore, the fluid will gradually diverge here, which will make it difficult for the fluid to be fully mixed.

[0007] Figure 2 Another existing microreactor 200 is shown. The microreactor includes a plurality of mixing units connected in sequence. The outer contour 201 of each mixing unit has an arcuate profile only at the upstream end, and the arcuate profile does not extend to the side. The side of the outer contour 201 is formed by two end fold lines. An inlet and an outlet are formed at the opposite ends of the outer contour 201. The outlet 202 of a single mixing unit is a straight channel with a constant cross section. In addition, a first fold line-shaped barrier 203 and a circular second barrier 204 are also provided in the single mixing unit. The second barrier 204 is closer to the outlet of the mixing unit relative to the first barrier 203. Thus, when the fluid enters the subsequent adjacent mixing unit through the outlet 202 of the previous mixing unit, it will impact on the first barrier 203, then flow to the two sides for diversion, and finally flow to the outlet of the mixing unit.

[0008] In the microreactor, the broken line side profile of the outer profile 201 causes a large energy loss of the fluid and increases the pressure drop. In addition, this will also increase the ineffective mixing area behind the first barrier 103, resulting in a poor impact effect and a reduced mixing efficiency.

[0009] In addition, for the above two microreactors, the structures of the outlets 102 and 202 of the mixing units will cause the fluid to have a certain tendency to "return to the original path" after impacting the first blocking parts 103 and 203. This is disadvantageous for the mixing efficiency and will increase the pressure drop.

[0010] against Figure 2 The microreactor in the experiment was carried out under liquid-liquid mixing conditions. Water and isooctyl alcohol were delivered from the inlet at a speed of 0.3 m / s. Figure 3 and Figure 4 They are shown separately Figure 2 The mixing and pressure conditions of the microreactor in Figure 3 It can be seen that the microreactor requires fluids to pass through at least 8 mixing units to achieve effective mixing between fluids. Effective mixing here is defined as the concentration difference between the left and right sides of the cavity in the mixing unit is less than 0.5%. Figure 4 It can be seen that the pressure drop of the fluid in the microreactor when it passes through 8 mixing units to achieve effective mixing is about 8680 Pa.

[0011] Similarly, for Figure 2The microreactor in the experiment was tested under gas-liquid mixing conditions. Water and air were delivered from the inlet at a speed of 0.3m / s. The experimental results showed that the microreactor required the fluid to pass through at least 6 mixing units to achieve effective mixing between the fluids, and the pressure drop was about 2.3 kPa.

[0012] In addition, for Figure 2 The microreactor in the experiment was used to test the efficiency of alcohol amine in absorbing carbon dioxide. The experimental process is to use alcohol amine to absorb carbon dioxide under low temperature conditions, and then heat to release carbon dioxide from the chemical solvent. Specifically, a carbon dioxide mixed gas with a volume fraction of 12% and a diethanolamine solution with a concentration of 30wt.% are respectively introduced into the microreactor 300 through the first inlet branch 301 and the second inlet branch 302 under 8MPa conditions, wherein the gas feed is 5-10Nm3 / h and the liquid feed is 50-80L / h. The results show that the carbon dioxide absorption rate does not exceed 92% at most. Summary of the invention

[0013] The present invention provides a microreactor for enhancing the mixing process, which can be used to avoid or at least reduce at least one of the above problems.

[0014] According to the present invention, a microreactor is proposed, comprising a plurality of mixing units connected in sequence along a longitudinal direction, each mixing unit comprising an outer shell, a flow cavity being formed in the outer shell, an inlet portion and an outlet portion being formed at opposite ends of each mixing unit along the longitudinal direction, respectively, and the inlet portion and the outlet portion are both connected to the flow cavity; the mixing unit further comprises a first blocking portion arranged in the flow cavity, the first blocking portion being centrally arranged in the flow cavity in a transverse direction perpendicular to the longitudinal direction and being located between the inlet portion and the outlet portion, so that the flow cavity forms a first forward channel defined by a first side profile of the outer shell and the first blocking portion, A second forward channel defined by a second side profile of the outer shell opposite to the first side profile and the first blocking portion, and a mixing area located between the first blocking portion and the outlet portion, the first forward channel and the second forward channel being connected to the mixing area; wherein, at the downstream ends of the first forward channel and the second forward channel, the microreactor is further provided with an auxiliary guide portion protruding and extending from the first side profile and the second side profile relative to each other but spaced apart, the auxiliary guide portion being configured to cause the fluids in the first forward channel and the second forward channel to flow into the mixing area relative to each other and impact each other.

[0015] The auxiliary flow guide can make the fluids in the first forward channel and the second forward channel impact each other more violently, and can significantly reduce the low flow rate portion in the mixing area and reduce the ineffective mixing area, thereby effectively improving the mixing efficiency of the microreactor.

[0016] In a preferred embodiment, the surface of the auxiliary guide portion facing the first forward channel or the second forward channel is configured as a plane or a curved surface.

[0017] In a preferred embodiment, the auxiliary flow guide is configured such that an angle between main movement directions of the fluid in the first forward channel and the second forward channel exceeds 90°.

[0018] In a preferred embodiment, the lateral dimension of the auxiliary guide portion does not exceed the lateral dimension of the first blocking portion.

[0019] In a preferred embodiment, the first side profile and the second side profile are axially symmetrically arranged relative to each other, and respectively include an arc-shaped upstream section and a linear downstream section, and the upstream section and the downstream section are smoothly connected.

[0020] In a preferred embodiment, the first blocking portion includes a laterally extending straight middle section and straight edge sections connected to both ends of the middle section, and the edge sections are inclined toward upstream relative to the middle section to form a fold angle between the edge sections and the middle section.

[0021] In a preferred embodiment, the linear downstream sections that are relatively axially symmetrically arranged are inclined in a relatively close manner toward the downstream; the linear downstream sections are arranged parallel to the edge sections so that the cross-section of the channel between the downstream sections and the edge sections remains constant.

[0022] In a preferred embodiment, the inlet portion forms an expansion channel that gradually expands in the longitudinal direction toward the downstream, and the outlet portion forms a neck between the linear downstream section of the mixing unit and the expansion channel of the inlet portion of another adjacent mixing unit.

[0023] In a preferred embodiment, the cross-sectional dimension of the narrowest position of the neck is not less than 1 / 4 of the maximum cross-sectional dimension of the inlet portion.

[0024] In a preferred embodiment, the maximum cross-sectional dimension of the inlet portion is between 100 micrometers and 2 millimeters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described in more detail below with reference to the accompanying drawings, wherein:

[0026] Figure 1 A schematic structural diagram of an existing microreactor is shown;

[0027] Figure 2 Another schematic structural diagram of an existing microreactor is shown;

[0028] Figure 3 Shows Figure 2 Schematic diagram of mixing efficiency of the microreactor during liquid-liquid mixing;

[0029] Figure 4 Shows Figure 2 Schematic diagram of the pressure drop of the microreactor during liquid-liquid mixing;

[0030] Figure 5 shows a schematic structural diagram of a microreactor according to one embodiment of the present invention;

[0031] Figure 6 Shows Figure 5 A partial enlarged view of the microreactor in FIG.

[0032] Figure 7 Shows Figure 5 Schematic diagram of liquid flow path of the microreactor during liquid-liquid mixing;

[0033] Figure 8 Shows Figure 5 Schematic diagram of mixing efficiency of the microreactor during liquid-liquid mixing;

[0034] Fig. 9 Shows Figure 5 Schematic diagram of the pressure drop of the microreactor during liquid-liquid mixing;

[0035] Fig.10 Shows Figure 5 Schematic diagram of liquid flow path of the microreactor during gas-liquid mixing;

[0036] Fig.11 Shows Figure 5 Schematic diagram of the liquid flow path of the microreactor during nitrification reaction.

[0037] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings.

[0039] In the present invention, "longitudinal direction" refers to the direction in which a fluid generally flows, e.g. Figure 6 In the paper, "lateral" refers to the direction extending up and down in the paper. Figure 6 The center should be understood as the left-right extending direction within the paper plane.

[0040] In the present invention, "upstream" refers to a side where a fluid is supplied, and "downstream" conversely refers to a side where a fluid flows.

[0041] Figure 5 FIG. 2 shows an embodiment of a microreactor 300 of the present invention. The microreactor 300 includes a plurality of mixing units 310 connected in sequence along the longitudinal direction. Figure 5 310. However, it should be understood that more or less mixing units 310 may be provided as required. The microreactor 300 also includes a fluid inlet channel 304 connected to the upstream of the first mixing unit in the mixing units connected in sequence. The fluid inlet channel 304 is communicated with the first inlet branch 301 and the second inlet branch 302 respectively. Fluid can enter the fluid inlet channel 304 through the first inlet branch 301 and the second inlet branch 302, and enter the mixing unit 310 to mix. The fluid here can be a gas, a fluid, or any other suitable flow medium. The microreactor 300 also includes a fluid output channel connected to the downstream of the last mixing unit in the mixing units connected in sequence, for conveying the fluid after mixing (even reacting) in the microreactor 300, so as to further process or use the like.

[0042] Figure 6 Shows Figure 5 A partial enlarged view of the microreactor 300 in FIG. Figure 6 As shown, the mixing unit 310 is formed as a planar mixing unit, including a flat outer shell. The outer shell is configured to be arranged axially symmetrically along the longitudinal axis, and thus includes two side profiles arranged oppositely, namely a first side profile and a second side profile. Each side profile includes an arc-shaped upstream section 312 and a linear downstream section 313. The linear downstream section 313 is smoothly connected to the arc-shaped upstream section 312. The two relatively arranged upstream sections 312 can be configured to be relatively inclined in the direction toward the downstream, so that the outer shell can form a generally inverted heart-shaped shape. A flow cavity is formed in the outer shell.

[0043] Also like Figure 6 As shown, an inlet and an outlet are respectively provided at opposite ends of the outer shell in the longitudinal direction. Both the inlet and the outlet are connected to the flow chamber. In addition, the inlet can be formed as an expansion channel 314 that gradually expands toward the downstream in the longitudinal direction. The profile of the expansion channel 314 is a linear profile. Thus, the fluid can enter the flow chamber in a divergent form through the expansion channel 314. The outlet can be formed as a constriction 315 connected between the flow chamber of the previous mixing unit and the expansion channel 314 of the inlet of the next mixing unit. Thus, each mixing unit 310 is formed as a whole in a shape similar to a "spade".

[0044] like Figure 6As shown in FIG. 1 , the mixing unit 310 further includes a first blocking portion 311 disposed in the flow chamber. It should be understood that the first blocking portion 311 may be formed by a solid block or by a plurality of blocks. Figure 5 The outer shell is formed by a through-hollowing as shown, as long as it can prevent the fluid from flowing therethrough.

[0045] The first blocking portion 311 includes a middle section 311B arranged laterally in the center of the flow chamber. The middle section 311B extends laterally and faces the expansion channel 314 of the inlet portion, and has a linear structure. The first blocking portion 311 also includes linear edge sections 311A ​​and 311C connected at both ends of the middle section. The free ends of the edge sections 311A ​​and 311C are inclined more toward the upstream relative to the middle section 311B, so that an angle is formed between the edge sections 311A ​​and 311C and the middle section 311B. Preferably, the angle between the two edge sections 311A ​​and 311C is not less than 50°.

[0046] In addition, Figure 6 As shown, the linear downstream section 313 can be arranged in parallel with the above-mentioned edge sections 311A ​​and 311C to form a forward channel with a constant cross section between them. The forward channel is symmetrically arranged, wherein the first forward channel 317 is defined between the first side profile and the first blocking portion 311, and the second forward channel 318 is defined between the second side profile and the first blocking portion 311. In addition, the edge sections 311A ​​and 311C are aligned with the corresponding downstream section 313 at the upstream end. The distance between the edge sections 311A ​​and 311C and the arc-shaped upstream end 312 of the outer shell also makes the cross section of the countercurrent channel formed between them remain relatively constant. This allows the fluid to remain relatively concentrated when flowing through the countercurrent channel and the forward channel, thereby providing a better basis for the mixing of the downstream fluids, making the impact of the fluid mixing more intense, and thus improving the mixing efficiency between the fluids. In addition, the countercurrent channels are designed to be relatively more, which makes it difficult to form a "dead zone" here, or the area of ​​the "dead zone" formed is relatively small.

[0047] The longitudinal dimension of the middle section 311B does not exceed 2 times the maximum cross-sectional dimension of the expansion channel 314. In addition, the edge sections 311A ​​and 311C gradually narrow in the direction toward the free end. The longitudinal length of the first barrier 311 as a whole accounts for 1 / 3 to 1 / 2 of the longitudinal length of the entire flow chamber. The so-called "second barrier" arranged at the downstream of the first barrier in the existing scheme can no longer be arranged between the downstream of the first barrier 311 and the outlet. In other words, a mixing area 319 is formed in the entire area between the downstream of the first barrier 311 and the upstream of the constriction 315 of the outlet. Since the first barrier 311 accounts for a large longitudinal length of the entire flow chamber, the downstream section 313 and the first barrier 311 have a stronger guiding effect on the fluid, and there are fewer "dead zones" in the flow chamber (especially the mixing area). This can improve the liquid holding capacity and flux of the microreactor 300.

[0048] In addition, at the downstream end of the first forward channel and the second forward channel, the microreactor is also provided with an auxiliary guide 316 that protrudes from the first side profile (its downstream section) and the second side profile (its downstream section) relative to each other but is spaced apart. The auxiliary guide 316 is configured to cause the fluids in the first forward channel 317 and the second forward channel 318 to flow into the mixing area 319 relative to each other and impact each other. It is preferred here that the fluids in the first forward channel 317 and the second forward channel 318 can change the flow direction through the action of the auxiliary guide 316, and make the angle between their main motion directions exceed 90°. This is conducive to intensifying the impact and mixing between the fluids, and can effectively reduce the "dead zone" or "low flow rate part" in the above-mentioned mixing area 319. In addition, the setting of the auxiliary guide 316 is also conducive to making the time for different fluids that need to be mixed and reacted to stay in the mixing area 319 closer. For a process that needs to react, the increase in the mixing area and the proximity of the mixing time are conducive to improving the uniformity and controllability of the reaction process. On the one hand, this is conducive to improving the mixing efficiency. On the other hand, this can also make the reaction products more stable and reduce by-products.

[0049] although Figure 5 and Figure 6 Only one pair of auxiliary guides 316 is shown for each mixing unit 310, but it should be understood that more pairs of auxiliary guides can be provided as needed. The surface of the auxiliary guide 316 facing the first forward channel 317 and the second forward channel 318 can be configured as a plane or an arc to change the direction of the fluid as needed.

[0050] The lateral dimension of a single auxiliary guide portion 316 does not exceed the lateral dimension of the first blocking portion 311. Preferably, the total lateral dimension of a pair of auxiliary guide portions 316 does not exceed the lateral dimension of the first blocking portion 311. This is conducive to improving the utilization rate of the mixing area 319 downstream of the first blocking portion 311, further reducing the "dead zone", and thus helping to improve the mixing efficiency.

[0051] The overall lateral dimension of the mixing unit 310 can be between 100 microns and 2 centimeters, and the overall thickness can be between 100 microns and 2 millimeters. The cross-sectional dimension of the fluid inlet channel 304 and the maximum cross-sectional dimension of the expansion channel 314 of each inlet portion can be between 100 microns and 2 millimeters, preferably between 100 microns and 500 microns. The cross-sectional dimension of the thinnest part of the neck 315 is not less than 1 / 4 of the dimension of the fluid inlet channel 304. The above-mentioned dimensional design is conducive to achieving a relatively balanced adjustment between improving the mixing efficiency and reducing the pressure drop. With the above-mentioned design, the transfer area (specific surface area) of the microprocessor 300 can reach up to about 60,000 m 2 / m 3 .

[0052] The microreactor 300 can be used as a reactor or a mixer, and can also be combined with a heat exchange unit, a collection unit or other reaction / mixing units to achieve a complete set of functions. It should be understood that in addition to the microreactor 300, in order to achieve the mixing and reaction of the fluid, other pumps, pipelines, flow meters, valves, control systems and other devices or equipment can also be set. The microreactor 300 can be used for single-phase systems, gas-liquid systems and liquid-liquid systems, and can also be used for low solid content and solid-containing multiphase systems with small home size. In addition, the chemical reactions applicable to the microreactor 300 of the present invention include oxidation, peroxidation, reduction, addition, displacement, substitution, polymerization, nitration, epoxidation, alkylation, hydrogenation, dehydrogenation; organic metal reaction, carbonylation, alkoxylation, halogenation, dehalogenation, carboxylation, arylation, coupling, condensation, dehydration, alcoholysis, hydrolysis, aminolysis, etherification, ketoneization, saponification, isomerization, diazotization, azotization, and enzyme catalytic reactions.

[0053] For the microreactor 300 of the present invention, when the fluid enters the flow chamber again through the constriction 315 of the outlet of the previous mixing unit and the expansion channel 314 of the inlet, the fluid can impact the first barrier 311 at high speed. Since the first barrier 311 is a broken line type, and the flow form of the fluid is dispersed, the fluid can change direction rapidly horizontally and flow to the above-mentioned countercurrent channel. In the region upstream of the first barrier 311, a high turbulence, high-speed difference flow state can be formed, thereby promoting the mixing between the fluids. At the same time, the fluid will not "return to the original path", or in other words, most of the fluid will not "return to the original path". This can avoid "return mixing", and can keep the residence time of the fluid relatively constant, thereby causing the flow process of the fluid to be more controllable, helping to accurately control and strengthen the mixing and reaction process.

[0054] In addition, when the fluid bypasses the edge segments 311A ​​and 311C of the first barrier 311 in the countercurrent channel, the fluid generally moves along an arc-shaped trajectory, and can further enhance the mixing effect by locally disturbing the edge segments 311A ​​and 311C. Subsequently, the two streams of fluid enter the mixing area 319 relative to each other through the linear forward channel after leaving the forward channel, and thus violently impact and mix together. The mixed fluid can leave the mixing unit through the neck 315 and enter the next mixing unit through the expansion channel of the inlet of the next mixing unit for further mixing. This structure improves the local flow velocity, shear rate and turbulence, while reducing the mass transfer distance, further strengthening the mixing and / or reaction process.

[0055] The beneficial effects of the microreactor 300 of the present invention will be further demonstrated through multiple embodiments below.

[0056] Example 1

[0057] The mixing efficiency of the microreactor 300 of the present invention was tested using a system containing fluorescent dyes. The mixing efficiency can be measured by measuring and calculating the mixing factor at the outlet. The specific calculation formula is:

[0058]

[0059] Among them, ψ represents the mixing factor, SD AIOD is the relative standard deviation of the target outlet concentration, SD AIOD，0 is the relative standard deviation of the concentration before mixing. The closer the mixing factor ψ is to 0, the worse the mixing effect is, and the closer it is to 1, the better the mixing effect is.

[0060] The safranin aqueous solution and water are introduced into the microreactor 300 of the present invention through the first inlet branch 301 and the second inlet branch 302, respectively. The flow rate of the first inlet branch 301 and the second inlet branch 302 is 20 L / min. The mixing factor ψ measured at the outlet is 0.9 ( Figure 2 The mixing factor of the existing microreactor 200 is about 0.6), and the pressure drop is about 0.1 MPa. This shows that the microreactor 300 of the present invention can achieve better fluid mixing without causing excessive pressure drop.

[0061] Example 2

[0062] The liquid-liquid mixing efficiency experiment was conducted on the microreactor 300. Figure 5 As shown, a microchannel is formed by a stainless steel base panel through a precision engraving machine, and the depth is about 500 microns. Water and isooctyl alcohol are introduced into the first entry branch 301 and the second entry branch 302 respectively, and a precision injection pump is used to realize feeding, and the entry flow rate is controlled to be about 0.3m / s. The cross-sectional size of the fluid entry channel 304 is 550 microns. The maximum transverse dimension of the mixing unit 310 is about 3.5 millimeters, and the longitudinal dimension (excluding the inlet and outlet) is about 2.5 millimeters. The expansion channel 314 of the inlet is directly opposite to the first barrier 311 in the flow chamber. The longitudinal dimension of the middle section 311B of the first barrier 311 is about 200 microns, and the transverse dimension is about 1 millimeter. The lengths of the edge sections 311A ​​and 311B of the first barrier 311 are both about 800 microns, and the width is reduced from 200 microns to 100 microns. The reverse flow distance of the reverse flow channel formed by the arc-shaped upstream end 312 of the outer shell and the edge segments 311A ​​and 311B is 150 microns (significantly smaller than the reverse flow distance of the center of the prior art to reduce the ineffective mixing area). A pair of auxiliary flow guides 316 are provided, and the lateral dimension of a single auxiliary flow guide 316 is 450 microns and the longitudinal dimension is 200 microns. The minimum cross-sectional dimension of the constriction 315 of the outlet portion is 200 microns.

[0063] The liquid-liquid mixing experiment was carried out using the microreactor 300. The experimental conditions were the same as those for Figures 2 to 4 The experimental conditions of the existing microreactor shown are the same. Figures 7 to 9 The corresponding experimental results are shown. Figure 7 As shown, the velocity vector distribution of the liquid-liquid mixing process of the microreactor 300 is gradually symmetrical and uniform, and before the strong impact mixing in the mixing chamber, the parallelism and consistency of the vector arrows of the fluid flow are high. This shows that in the mixing unit 310 of the microreactor 300, the velocity vector distribution is highly controllable. This is conducive to the accurate prediction and control of the mixing effect. Figure 8As shown, the microreactor 300 can achieve effective mixing of the fluid after passing through four mixing units. Fig. 9 It shows that the pressure drop of the fluid passing through 4 mixing units to achieve effective mixing is about 8520 Pa.

[0064] Experiments have shown that the microreactor 300 of the present invention can achieve effective mixing of fluids using fewer mixing units 310. Figure 2 Compared with the existing microreactor 200, the microreactor 300 of the present invention can greatly improve the mixing efficiency and shorten the mixing time while maintaining low pressure drop and high flux, thereby reducing the number of required mixing units and making the microreactor have a smaller volume.

[0065] Example 3

[0066] The same microreactor 300 as in Example 2 was used to carry out a mixed reaction of methyl chloride and salicylic acid. The experiment was carried out by adding methyl chloride to 25% salicylic acid under the conditions of 22MPa and 350K. The results showed that the required reaction time was about 230s and the yield was 99%, which was 1% higher than the traditional method which required a reaction time of 10h. In addition, the microreactor 300 clearly showed advantages such as simple operation, low cost and greatly reduced required space during the experiment.

[0067] Example 4

[0068] The gas-liquid mixing efficiency experiment was conducted on the microreactor 300. Figure 5 As shown, the overall thickness (depth) is about 500 microns. The maximum transverse dimension (width) of the flow chamber is about 4 mm, and the longitudinal dimension (excluding the inlet and outlet) is about 3 mm. The expansion channel 314 of the inlet is directly opposite to the first barrier 311 in the flow chamber. The longitudinal dimension of the middle section 311B of the first barrier 311 is about 250 microns, and the transverse dimension is about 1.2 mm. The length of the edge segments 311A ​​and 311B of the first barrier 311 is about 1 mm, and the width is reduced from 250 microns to 150 microns. The distance of the reverse flow of the countercurrent channel formed by the arc-shaped upstream end 312 of the outer shell and the edge segments 311A ​​and 311B is 200 microns (significantly smaller than the reverse flow distance of the center of the prior art to reduce the ineffective mixing area). A pair of auxiliary guides 316 are provided, and the transverse dimension of a single auxiliary guide 316 is 450 microns and the longitudinal dimension is 200 microns. The minimum cross-sectional dimension of the neck 315 of the outlet is 250 microns.

[0069] The microreactor 300 was used to conduct a gas-liquid mixing experiment. The first inlet branch 301 and the second inlet branch 302 respectively transported deionized water and air, with an operating temperature of 298 K and a viscosity of 8.9×10 -4 Pa·s, surface tension coefficient 0.07N·m-1, and inlet flow rate 0.3m / s. The results show that for gas-liquid mixing, the microreactor 300 can achieve effective mixing of the fluid after passing through 4 mixing units, and the pressure drop of the fluid after passing through 4 mixing units to effective mixing is about 2.5 kPa. Fig.10 As shown, the auxiliary guide portion 316 can effectively change the direction of fluid movement, adjust the impact angle, and effectively improve the mixing efficiency.

[0070] and Figure 2 Compared with the gas-liquid mixing experimental results of the existing microreactors in , the microreactor 300 can greatly improve the mixing efficiency while maintaining low pressure drop and large flux, and has advantages in mixing time, the number of mixing units required, and the overall volume.

[0071] Example 5

[0072] The nitration reaction efficiency experiment was conducted on the microreactor 300 of the present invention. The reactor is made of stainless steel, and a heat exchanger is arranged on the outer layer to realize the closed-circuit circulation flow of the heat transfer fluid, so as to realize the integration of mixing and heat transfer.

[0073] The current general process for preparing isooctyl nitrate is to add isooctyl alcohol to a prepared sulfuric acid and nitric acid mixture for nitration reaction, and then obtain the finished product through acid washing, alkali washing and water washing. Since the reaction is a highly exothermic reaction, in order to avoid the risk of thermal runaway, the feed speed of the traditional kettle reactor is very slow, and the reaction process takes more than 1 hour.

[0074] The microreactor 300 is used to carry out the reaction to prepare isooctyl nitrate. It can not only enhance the mixing and reaction rate, but also significantly increase the heat transfer rate and improve the process safety. Fig.11 The liquid flow path in the experiment is displayed, which shows that the microreactor 300 can make the liquid phase distribution in the experiment uniform and controllable, and the transfer efficiency is high. This results in the microreactor 300 not only shortening the reaction residence time, but also achieving efficient and directional conversion of the reactants by controlling the reaction conditions. For example, in the reaction process with dinitrochlorobenzene as the target, the dinitro product can account for more than 99% of the product.

[0075] Example 6

[0076] The experiment of the efficiency of alcoholamine in absorbing carbon dioxide was conducted on the microreactor 300. The structure of the microreactor 300 is the same as that in Example 4.

[0077] The experimental process is to use alcohol amine to absorb carbon dioxide under low temperature conditions, and then heat it to release carbon dioxide from the chemical solvent. Specifically, a carbon dioxide mixed gas with a volume fraction of 12% and a diethanolamine solution with a concentration of 30wt.% enter the microreactor 300 through the first inlet branch 301 and the second inlet branch 302 under 8MPa conditions, wherein the gas feed is 5-10Nm 3 / h, liquid feed is 50-80L / h.

[0078] The results show that under high liquid-gas ratio conditions, the carbon dioxide absorption rate exceeds 95%, which has a significant absorption effect. Accordingly, the microreactor 300 has the advantages of fast absorption speed, high absorption capacity, and high purity of recovered carbon dioxide.

[0079] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A microreactor, comprising a plurality of mixing units connected in sequence along a longitudinal direction, each mixing unit comprising an outer shell, a flow cavity is formed in the outer shell, an inlet and an outlet are formed at opposite ends of each mixing unit along the longitudinal direction, and both the inlet and the outlet are connected to the flow cavity; The inlet portion forms an expansion channel that gradually expands in the longitudinal direction toward the downstream, and the outlet portion forms a constriction between the linear downstream section of the mixing unit and the expansion channel of the inlet portion of the adjacent other mixing unit; The mixing unit further comprises a first blocking portion disposed in the flow chamber, the first blocking portion being centrally arranged in the flow chamber in a transverse direction perpendicular to the longitudinal direction and being located between the inlet portion and the outlet portion, so that the flow chamber forms a first forward passage defined by a first side contour of the outer shell and the first blocking portion, a second forward passage defined by a second side contour of the outer shell opposite to the first side contour and the first blocking portion, and a mixing area between the first blocking portion and the outlet portion, the first forward passage and the second forward passage being connected to the mixing area; The first side profile and the second side profile are relatively arranged in an axisymmetric manner, and respectively include an arc-shaped upstream section and a linear downstream section, and the upstream section and the downstream section are smoothly connected; The first blocking portion comprises a laterally extending straight middle section and straight edge sections connected to both ends of the middle section, the edge sections are inclined toward the upstream relative to the middle section to form a fold angle between the edge sections and the middle section, the straight downstream sections arranged relatively close to each other in an axisymmetric manner are inclined toward the downstream, the straight downstream sections are arranged in parallel with the edge sections to keep the cross section of the channel between the downstream sections and the edge sections constant, and the edge sections are aligned with the corresponding straight downstream sections at the upstream end; in, At the downstream ends of the first forward channel and the second forward channel, the microreactor is also provided with an auxiliary guide portion protruding and extending from the first side profile and the second side profile relative to each other but spaced apart, the auxiliary guide portion being configured to cause the fluids in the first forward channel and the second forward channel to flow into the mixing area relative to each other and impact each other, and the auxiliary guide portion being configured to make the angle between the main movement directions of the fluids in the first forward channel and the second forward channel exceed 90°.

2. The microreactor according to claim 1, characterized in that The surface of the auxiliary air guide portion facing the first forward passage or the second forward passage is configured as a plane or a curved surface.

3. The microreactor according to claim 1 or 2, characterized in that: The lateral dimension of the auxiliary air guide portion does not exceed the lateral dimension of the first blocking portion.

4. The microreactor according to claim 1, characterized in that The cross-sectional dimension of the thinnest portion of the neck is not less than 1 / 4 of the maximum cross-sectional dimension of the inlet portion.

5. The microreactor according to claim 4, characterized in that The maximum cross-sectional dimension of the inlet portion is between 100 micrometers and 2 millimeters.

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