A multi-stage stirred tubular continuous reactor and its use method

Abstract

The invention discloses a multi-stage stirring tubular continuous reactor and a method for using the same, and relates to the field of pharmaceutical chemical fine chemical equipment. The technical scheme thereof mainly comprises: a cylindrical tubular shell with a large aspect ratio, one end of which is provided with a feed port, and the other end of which is provided with a discharge port; a coaxial multi-stage stirring impeller and a multi-stage radial blocking component separating upper and lower stirring impellers are arranged inside the cylindrical tubular shell; the multi-stage stirring impeller is fixed on the same stirring shaft driven by a power source; a primary stirring impeller and a primary radial blocking component form a primary mixing unit; a multi-stage mixing unit is finally formed by the multi-stage stirring impeller and the multi-stage radial blocking component and is fixed inside the cylindrical tubular shell; the diameter of the radial blocking component is smaller than the inner cavity diameter of the cylindrical tubular shell; the effect is that the advantages of a microchannel reactor and an active agitator are combined; on the basis of retaining the large specific surface area of ​​the microchannel equipment, active stirring is added, the heat and mass transfer effect is greatly enhanced, and the use range of the microchannel reactor or the stirred reactor is greatly broadened.

Description

Technical Field

[0001] The invention relates to the field of pharmaceutical chemical and fine chemical equipment, and more specifically, to a multi-stage stirring tube type continuous reactor. Background Art

[0002] In the prior art, for high viscosity systems, mixed reaction processes with solid-liquid two-phase processes, and synthesis processes of micro-nano particles, strong stirring is often set in the reactor or reactor and the structure of the agitator is optimized to achieve uniform mixing, including the use of experimental and numerical simulation methods to analyze the influence of factors such as different types of blades, rotation speed and installation height on the internal flow field of the agitator. For example, 1. Wang Yinghui et al. (Chemical Industry and Engineering, 2023, 40(2): 123-132.) used a laser Doppler velocimeter to measure the stirring power of four types of disc turbine impeller agitators under the same conditions. Under the same mixing volume and power consumption, the arc blade requires the least stirring power compared with other types of blades, and there is a good consistency between the predicted value of the numerical simulation and the experimental results. 2. Huang Cong et al. (Journal of Chemical Engineering of Colleges and Universities, 2022, 36(4): 554-561.) used a pulse tracer method and a saturated Na2SO4 solution as a tracer. By measuring the changes in the conductivity of three different blade structures at the outlet, namely, a propeller, a four-pitch blade propeller, and an airfoil propeller, they found that the mixing time of the four-pitch blade propeller and the propeller was shorter and had a greater effect on promoting material mixing.

[0003] However, even if the conventional stirred reactor mentioned above is structurally optimized, it is often difficult to avoid the following problems in the process of feeding and chemical reaction: 1) Insufficient stirring and stirring "dead zone" problems will lead to local over-proportioning, resulting in the production of by-products, which is almost unavoidable in conventional stirred reactors; 2) The heat exchange problem of conventional reactors. Due to the limitation of insufficient specific surface area (surface area and volume ratio), the heat exchange efficiency of conventional stirred reactors is not high enough, and local overheating, i.e. "hot spots", often occurs. Local overheating often leads to the generation of by-products, which leads to a decrease in yield and selectivity; and if the large amount of heat generated by the violent reaction in production cannot be discharged in time, it will lead to material impact accidents or even explosions. 3) The problem of back-mixing in the kettle: Conventional single-pot reactions often use the method of gradually adding reactants to prevent the reaction from being too violent. In many reactions, the long residence time of reactants, products or intermediate transition products under reaction conditions will lead to the generation of by-products. 4) Scale-up effect of conventional stirred tank reactors: Due to the limitations of the external dimensions of conventional stirred tank reactors (such as aspect ratio, etc.), and as the scale of the reaction increases, the control of mass transfer and heat exchange gradually weakens, resulting in a very obvious scale-up effect of the stirred tank reactor.

[0004] In addition, compared with conventional stirred reactors, the specific surface area is very large, and the microreactor has extremely high mixing efficiency (radial complete mixing is achieved in the millisecond range), extremely strong heat transfer capacity (heat transfer coefficient can reach 25,000W / (m2·K)) and extremely narrow residence time distribution (almost no backmixing, basically close to plug flow). There are also attempts to use conventional microchannel reactors for high viscosity systems or solid-liquid two-phase continuous processes, but because the channel size of the process fluid in the microreactor (characteristic size is usually between 10-1000 microns) is very small, actual operation will cause the high viscosity system to have too much pressure drop or even produce solids that will cause blockage and make it unusable, or because there is no transmission equipment, the micro-nano particle system will have too much pressure drop or agglomeration will cause blockage and cannot be operated for a long time.

[0005] Therefore, in order to solve the above technical problems, the present application proposes a multi-stage stirred tubular continuous reactor and a method for using the same. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a multi-stage stirred tubular continuous reactor and a method for using the same.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a multi-stage stirring tubular continuous reactor, comprising a cylindrical tubular shell with a large aspect ratio, one end of which is provided with a feed inlet, and the other end of which is provided with a discharge port, the interior of the cylindrical tubular shell is provided with a coaxial multi-stage stirring impeller and a multi-stage radial blocking component separating the upper and lower stirring impellers, the multi-stage stirring impeller is fixed on the same stirring shaft driven by a power source, the first-stage stirring impeller and the first-stage radial blocking component constitute a first-stage mixing unit, and the multi-stage mixing unit is finally formed by the multi-stage stirring impeller and the multi-stage radial blocking component and is fixed inside the cylindrical tubular shell, and the diameter of the radial blocking component is smaller than the inner cavity diameter of the cylindrical tubular shell;

[0008] Among them, the ratio of the length of the cylindrical tubular shell to the inner cavity diameter is greater than 5:1, the number of the mixing units composed of the stirring impeller and the radial blocking component is greater than 3, and the number of the feed ports is not less than 2.

[0009] Preferably, the single-stage radial blocking component is a baffle, the ratio of the axial length h1 of the single-stage stirring impeller to the thickness b of the single-stage radial blocking component is 30:1-5:1, and the characteristic index x=d1*D / (d*d) among the stirring impeller diameter d1, the radial blocking component diameter d and the cylindrical tubular shell inner cavity diameter D is in the range of 0.5-5.

[0010] Preferably, the ratio of the axial length h1 of the single-stage stirring impeller to the thickness b of the single-stage radial blocking component is 30:1-20:1, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller, the diameter d of the radial blocking component and the inner cavity diameter D of the cylindrical tubular shell 1 is in the range of 0.5-3.

[0011] Preferably, the single-stage radial blocking component is a baffle or a block, the ratio of the axial length h1 of the single-stage stirring impeller to the thickness b of the single-stage radial blocking component is 5:1-1:10, and the characteristic index x=d1*D / (d*d) among the stirring impeller diameter d1, the radial blocking component diameter d and the cylindrical tubular shell inner cavity diameter D is in the range of 0.1-2.

[0012] Preferably, the ratio of the axial length h1 of the single-stage stirring impeller and the thickness b of the single-stage radial blocking component is 5:1-1:3, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller, the diameter d of the radial blocking component and the inner cavity diameter D of the cylindrical tubular shell is in the range of 0.2-0.5.

[0013] Preferably, the baffle and the block are in annular or cylindrical shapes, and a pattern structure is carved on the axial cylinders of both.

[0014] Preferably, the stirring impeller is a six-straight-blade open stirring impeller, a six-straight-blade disc turbine impeller, a screw-belt stirring impeller, a propeller stirring impeller, a Brumakin stirring impeller, a gear-shaped blade, a four-pitched-blade impeller or a disc turbine impeller.

[0015] Preferably, the outer side wall of the cylindrical tubular shell is matched with a sleeve-type outer jacket to meet process temperature control and heat exchange requirements.

[0016] Preferably, a bearing is installed at the end of the cylindrical tubular shell, the stirring shaft sleeve is arranged in the bearing and fixed to the inner ring of the bearing, and its head is connected to the power source through a coupling, a spacer is nested between the inner and outer rings of the bearing, and a support shaft is arranged inside the cylindrical tubular shell to support the radial blocking component.

[0017] The method of using the above-mentioned multi-stage stirred tubular continuous reactor comprises the following steps:

[0018] Step 1: Pump two or more materials into the reactor at a certain flow rate through a feed pump;

[0019] Step 2: When the power source is turned on at a certain speed, the power source drives the rotation of the stirring shaft, and finally drives the rotation of the multi-stage stirring impeller, so that the material pumped from the feed inlet is mixed at the first stage through the stirring impeller;

[0020] Step 3: After the first layer of radial blocking components are merged, the first stage of the mixing unit is completed and the next mixing unit is reached, and so on, and then the mixing impellers in other mixing units are mixed or reacted step by step;

[0021] Step 4: Finally discharged through the discharge port.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention combines the advantages of the microchannel reactor and the active agitator, and increases the process conditions of active stirring feeding on the basis of retaining the large specific surface area of ​​the microchannel device. At the same time, the high aspect ratio enables the reactor to have the advantages of efficient mixing and heat exchange of the microreactor, greatly enhancing the effect of heat and mass transfer, thereby solving the heat exchange problem of the conventional stirred reactor in the background technology due to insufficient surface area;

[0024] 2. The present invention broadens the scope of use of microchannel reactors or stirred reactors. Through CFD numerical simulation, it can be found that after the third-stage mixing unit, the two streams of materials can be completely mixed. The stirring function of this product can ensure that the objects are quickly mixed after feeding, and it is not easy for micro-nano particles to agglomerate or scale to cause excessive pressure drop or even blockage. The annular gap formed by the radial blocking component enables the reactor to have the advantages of efficient mixing and heat exchange of microreactors. The design of the radial blocking component can also reduce inter-stage backmixing, ensure good mixing within the stage, and present a plug flow trend as a whole, avoiding the shortcomings of a simple kettle stirring type or conventional microchannel reactor, such as insufficient stirring, "dead zone", backmixing in the kettle, and "amplification" effect of the reactor, as well as the problem of large pressure drop or easy blockage caused by the small size of the microchannel, thereby solving the problems of insufficient stirring and stirring "dead zone", backmixing in the kettle, amplification effect, and small channel size in the microreactor in the background technology, which is easy to be blocked;

[0025] 3. The present invention designs different ratios of the axial length of the single-stage stirring impeller and the thickness of the single-stage radial baffle, as well as the diameter of the stirring impeller, the diameter of the radial baffle and the inner diameter of the cylindrical tubular shell, so that the reactor is suitable for high-viscosity systems or meets the process conditions of producing solids or even solid slurry (solid content can reach 20%) during the reaction process, and can also be well applied to the synthesis process of nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1It is a schematic diagram of the structure of the present invention (including an enlarged diagram of the local structure A and a schematic diagram of the local cross-sectional structure B);

[0028] Figure 2 A schematic diagram of the types of stirring impellers used in the present invention;

[0029] Figure 3 A cloud diagram of a multi-stage stirred tubular mixing reactor simulated by CFD in the present invention;

[0030] Figure 4 Schematic diagram of the relationship between the mixing index and the micro-stirrer level of four concentration solutions at different rotation speeds in Example 1 of the present invention;

[0031] Figure 5 The numerical simulation display diagram of the solid-liquid two-phase flow system corresponding to different stirring impellers (rotation speed: 100rpm; particle diameter: 0.5mm, particle density: 1550kg / m3);

[0032] Figure 6 It is a relationship diagram between the mixing index and the micro-stirrer order of four concentrations of glycerol and aqueous solution (glycerol and aqueous solution can be used as nano-synthesis process materials) at different rotation speeds in Example 2 of the present invention;

[0033] Figure 7 A schematic diagram of the annular pattern of the radial blocking component on the outer side of the cylinder;

[0034] Figure 8 For annotation Figure 1 The parameters of each structure in Figure 1 Structural parameters of each component and key feature dimensions).

[0035] In the figure: 1. cylindrical tubular casing; 2. feed inlet; 3. discharge outlet; 4. stirring impeller; 5. radial blocking component; 6. power source; 7. stirring shaft; 8. bearing; 9. coupling; 10. spacer; 11. support shaft. DETAILED DESCRIPTION

[0036] Example 1 (Multi-stage stirred tubular continuous flow mixing reactor)

[0037] like Figure 1-5 as well as Figure 8As shown, this embodiment designs a multi-stage stirring tubular continuous reactor, including a cylindrical tubular shell 1 with a large aspect ratio, one end of which is provided with a feed port 2, and the other end of which is provided with a discharge port 3, the interior of the cylindrical tubular shell 1 is provided with a coaxial multi-stage stirring impeller 4 and a multi-stage radial blocking component 5 separating the upper and lower stirring impellers 4, the multi-stage stirring impeller 4 is fixed on the same stirring shaft 7 driven by a power source 6, the first-stage stirring impeller 4 and the first-stage radial blocking component 5 form a first-stage mixing unit, and the multi-stage mixing unit is finally formed by the multi-stage stirring impeller 4 and the multi-stage radial blocking component 5. Inside the cylindrical tubular shell 1, a bearing 8 is installed at the end of the cylindrical tubular shell 1, and the stirring shaft 7 is sleeved in the bearing 8 and fixed to the inner ring of the bearing 8. The stirring shaft 7 is rotatably supported by the bearing 8, and its head is connected to the power source 6 through a coupling 9. A spacer 10 is nested between the inner and outer rings of the bearing 8, which can accurately control the axial clearance between the inner and outer rings of the bearing 8 to ensure the normal operation of the bearing 8. A support shaft 11 is provided inside the cylindrical tubular shell 1 to support the radial blocking component 5, and the diameter of the radial blocking component 5 is smaller than the inner cavity diameter of the cylindrical tubular shell 1.

[0038] The above-mentioned first-stage stirring impeller 4 and the first-stage radial blocking component 5 constitute a first-stage mixing unit, so that a multi-stage mixing unit can be formed and fixed in the cylindrical tubular shell 1. When the stirring shaft 7 is directly driven by a motor or driven by magnetic coupling (power source 6), the mixing function of the reactor can be realized.

[0039] One end of the cylindrical tubular shell 1 is opened to form two or more feed ports 2 (not less than 2), and the other end is opened to form a discharge port 3, and then two or more materials are pumped into the tubular reactor at a certain flow rate through a feed pump (the materials can be gas or liquid), and then when the power source 6 is turned on at a certain speed, the materials pumped from the feed port 2 can be mixed (actively stirred) at the first stage through the stirring impeller 4, and then the first stage mixing unit is completed after converging through the first layer of radial blocking components 5, and then mixed or reacted step by step through other mixing units, and finally discharged through the discharge port 3.

[0040] The number of mixing units composed of the stirring impeller 4 and the radial blocking component 5 is greater than 3, and is generally more than 10 in actual use. The number of mixing units greater than 3 can realize multi-stage mixing of materials, improve mixing uniformity, enhance plug flow to reduce back mixing and flexibly control the reaction process; the number of feed ports 2 is not less than 2, which can meet the simultaneous feeding of multiple materials, is conducive to the development of diversified reactions, and can also enhance the mixing effect. Multiple material flows interact with each other and the flow ratio can be flexibly adjusted to optimize the overall reaction process.

[0041] In addition, the ratio of the axial length h1 of the single-stage stirring impeller 4 to the thickness b of the single-stage radial blocking member 5 of the present invention is 30:1-5:1, preferably 30:1-20:1 (to fully ensure the axial length of the stirring impeller 4). Within these ratios, it can be ensured that the stirring impeller 4 has sufficient length to produce effective stirring in each mixing unit. If the ratio h1 / b is too small, the stirring impeller 4 is relatively short, and the stirring effect is limited. It is difficult to effectively overcome the viscosity of the high-viscosity system, and it is also difficult to disperse the solid or solid slurry well. For example, when h1 is too short, it may not be possible to form sufficient vortex and shear force to mix high-viscosity fluids or suspended solids. If the ratio is too large, the structure of the mixing unit may be unreasonable, which may affect the flow path and residence time of the material in the unit, and is not conducive to improving the mixing efficiency. At the same time, the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller 4, the diameter d of the radial blocking component 5 and the inner cavity diameter D of the cylindrical tubular shell 1 is in the range of 0.5-5, preferably 0.5-3 (sufficiently ensuring the axial size of the stirring impeller 4). The design of these characteristic index ranges ensures a reasonable spatial relationship between the stirring impeller 4, the radial blocking component 5 and the inner cavity of the cylindrical tubular shell 1. When x is within a suitable range, the impeller 4 has a suitable transverse area, so that when the impeller 4 rotates, a flow field of sufficient strength can be generated, so that the high-viscosity fluid can be fully stirred. At the same time, there is also a connection between the radial blocking component 5 and the cylindrical tubular shell 1 to avoid a small annular gap (the difference between the inner cavity diameter D of the cylindrical tubular shell 1 and the diameter d of the radial blocking component 5 forms an annular gap), which makes it difficult for materials to pass through. The generated solid particles have enough space to pass through and will not block the channel due to the narrow space. This is crucial for the process of generating solids during the reaction, because blockage will cause the reaction to be interrupted. The present invention can effectively avoid this situation and realize the continuous operation of the solid generation process, so that the present invention is particularly suitable for high-viscosity systems or meets the process conditions of generating solids during the reaction, or even solid slurry (solid content can reach 20%) feeding.

[0042] The size of the annular gap Dd is not less than 300 microns, preferably not less than 1000 microns.

[0043] The types of stirring impellers 4 include but are not limited to six straight-blade open stirring impellers, six straight-blade disc turbine impellers, screw-ribbon stirring impellers, propeller stirring impellers, Brumakin stirring impellers, gear-shaped blades, four-pitch blade impellers (45° PBT), and disc turbine impellers (Rushton). Among them, the screw-ribbon stirring impellers, propeller stirring impellers, four-pitch blade impellers and Brumakin stirring impellers perform better when used, and all four can produce good material flow effects. Whether it is the simultaneous axial and circumferential movement of the spiral impeller, the efficient axial flow generated by the propulsion impeller, or the complex flow field formed by the four-pitch impeller (45°PBT) including axial and circumferential flows, and the strong convection generated by the Brumakin impeller, all of them are conducive to the rapid flow and full mixing of materials in the reactor, reducing the stratification and aggregation of materials. In addition, the stirring speed of the impeller 4 can be controlled and adjusted in the range of 0-1000rpm. After actual operation, the mixing effect is better at 200-1000rpm. The ratio of the length of the cylindrical tubular shell 1 to the inner cavity diameter is greater than 5:1. If the length is shorter than the inner cavity, the residence time of the material in the reactor will also be shorter, and it is very easy to have incomplete mixing. The length of the cylindrical tubular shell 1 and the inner cavity diameter are preferably greater than 8:1, or even 10:1, so as to fully ensure the complete mixing of the materials, wherein the radial blocking component is a baffle.

[0044] Furthermore, the outer side wall of the cylindrical tubular shell 1 is matched with a sleeve-type outer jacket to meet the process temperature control and heat exchange requirements.

[0045] This embodiment uses the following six implementation methods to specifically illustrate that it is particularly suitable for high-viscosity systems or process conditions for producing solids, or even solid slurry feed. The first three implementation methods are parameter ratios of reactors from different scales including laboratory, pilot and production level equipment; the last three are simulation results and actual experimental results of the reactor in different application scenarios, including continuous mixing of high-viscosity systems and continuous process applications for producing solids and continuous reaction processes for solid slurry feed.

[0046] Implementation Method 1: Laboratory-level Multi-stage Mixing

[0047] The number of stages is 5, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*5 / D = 5.2;

[0048] h1 / b=15, x=d1*D / (d*d)=0.957, annular gap (Dd) / 2=0.2mm=750 microns

[0049] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the baffle (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the baffle (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the baffle and the inner diameter of the cylindrical tubular housing 1.

[0050] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0051] The specific parameters are: wa = wb = 6.25mm, wc = 6.25mm,

[0052] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 50 mm, the baffle diameter (d) is 48.5 mm, the impeller diameter 4 is 45 mm, the agitator shaft diameter (d2) is 14 mm,

[0053] The axial length of the stirring impeller 4 (h1) = 30 mm, the height of the single-stage mixing unit (h2) = 52 mm, and the thickness of the baffle (b) = 2 mm.

[0054] Implementation Method 2: Pilot-Scale Multi-Stage Stirred Mixing Reactor

[0055] The number of stages is 8, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*8 / D = 9.6;

[0056] h1 / b=20, x=d1*D / (d*d)=0.956, annular gap (Dd) / 2=2mm=2000 microns

[0057] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the baffle (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the baffle (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the baffle and the inner diameter of the cylindrical tubular housing 1.

[0058] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0059] The specific parameters are: inlet channel diameter wa = wb = 20mm, outlet channel diameter wc = 20mm,

[0060] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 300 mm, the baffle diameter (d) is 296 mm, the impeller diameter 4 is 285 mm, the agitator shaft diameter (d2) is 80 mm,

[0061] The axial length of the stirring impeller 4 (h1) = 300 mm, the height of the single-stage mixing unit (h2) = 360 mm, and the thickness of the baffle (b) = 15 mm.

[0062] Implementation Method 3: Structural Parameters of Production-Level Multi-stage Stirring and Mixing Reactor

[0063] The number of stages is 10, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*10 / D = 9.38;

[0064] h1 / b=25, x=d1*D / (d*d)=1.00, annular gap (Dd) / 2=5mm=5000 microns

[0065] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the baffle (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the baffle (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the baffle and the inner diameter of the cylindrical tubular housing 1.

[0066] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0067] The specific parameters are: inlet channel diameter wa = wb = 50mm, outlet channel diameter wc = 50mm,

[0068] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 800 mm, the baffle diameter (d) is 790 mm, the impeller diameter 4 is 785 mm, the agitator shaft diameter (d2) is 150 mm,

[0069] The axial length of the stirring impeller 4 (h1) is 625 mm, the height of the single-stage mixing unit (h2) is 750 mm, and the thickness of the baffle (b) is 25 mm.

[0070] Implementation Method 4 Numerical Simulation of Mixing Effect of High Viscosity Fluid

[0071] Mixing of high-viscosity fluids is a basic unit operation in industrial production and is widely used in rubber, chemical, food, pharmaceutical and other fields. In industrial production, it is generally believed that fluids with a viscosity less than 5 Pa·s in the mixing equipment are low-viscosity fluids, fluids with a viscosity of 5 to 50 Pa·s are medium-viscosity fluids, fluids with a viscosity of 50 to 500 Pa·s are high-viscosity fluids, and fluids greater than 500 Pa·s are ultra-high-viscosity fluids. Four syrup solutions with different mass fractions were used as stirring materials, and their main parameters such as density and viscosity were obtained through actual measurement, as shown in Table 1.

[0072] Table 1 Rheological properties of stirring media

[0073]

[0074] In order to quantitatively evaluate the mixing degree of the medium, the variance of the two fluids inside the agitator is calculated to quantify and analyze the mixing degree, and the mixing index (MI) value is defined as:

[0075]

[0076] In the formula, σ refers to the standard deviation of the fluid mass fraction at any cross section along the flow direction, σ max The larger the mixing index, the better the mixing effect. When the two fluids are in a completely separated state, the mixing index MI is 0, and when the two fluids are completely mixed, the mixing index MI is 1.

[0077]

[0078] Where N refers to the number of fluid mass fraction sampling points on a certain cross section along the flow direction, c i refers to the mass fraction of the fluid at the i-th sampling point, It refers to the expected value of the fluid mass fraction after the mixing is completed, that is, the optimal mixing mass fraction (in this article The value is 0.5).

[0079] In the process of stirring and mixing high viscosity fluids, the number of reactors is one of the key factors affecting the flow pattern and mixing effect. As the number of reactors N increases, the mixing efficiency MI value changes as follows: Figure 4 As shown in the figure, as the number of reactor stages increases, the mixing effect of the fluid is also enhanced, but the energy consumption of the system also increases accordingly. At the same time, considering the difficulty of processing and manufacturing, it is necessary to balance the relationship between the change of fluid viscosity and the number of stages in practical applications.

[0080] First, in a low-stage reactor, the flow field is relatively simple. High-viscosity fluids form localized vortices centered on the blades under the action of the reactor. Due to the high viscosity of the fluid, the flow field is highly non-uniform, and the flow velocity gradient of the fluid changes relatively slowly. As the number of reactor stages increases, multi-stage reactors introduce more shear layers, driving the flow of liquid in the surrounding dead zones to form some smaller vortex structures. At this time, high-viscosity fluids are more evenly dispersed and mixed. The fluid is squeezed and stretched when it flows through the baffle between two adjacent stages. This separation and reorganization process intensifies the unbalanced collision between the fluids, helps to overcome the cohesive force of the high-viscosity fluid, and improves the mixing effect.

[0081] Implementation 5: Application of Solid Production Process

[0082] The acid-binding agent (the deacid reagent) is composed of an organic weak base, and commonly used ones include pyridine, triethylamine and diisopropylethylamine. Triethylamine is a weak base with a pka (conjugate acid) of 10.75. It is often used as an acid-binding agent. If HCl is produced in the system, triethylamine hydrochloride will be formed. Triethylamine hydrochloride is generally insoluble in organic solvents. If the product is easily soluble in the reaction solvent, then triethylamine is selected as the acid-binding agent at this time, and triethylamine hydrochloride can be directly separated from the product by solubility difference.

[0083] However, in practical applications, especially in the development of conventional microchannel reaction processes, the above system will face the problem of precipitated triethylamine hydrochloride blocking the reaction equipment. Therefore, the multi-stage stirred tube continuous flow mixing reactor developed by this patent can avoid blockage and realize continuous operation of the solid production process.

[0084] The pilot-scale multi-stage stirred tubular continuous flow mixing reactor described in the second embodiment is used, wherein the stirring impeller 4 is a six-straight-blade open stirring impeller.

[0085] The specific steps are as follows:

[0086] Step 1: Dissolve the substrate chalcol in anhydrous THF at a concentration of 1 mol / L, then add an equivalent amount of triethylamine as the continuous phase; at the same time, dissolve acetyl chloride in anhydrous THF at a concentration of 1 mol / L as the dispersed phase. Both reaction solutions are stored in a 0°C low-temperature bath for later use;

[0087] Step 2: The multi-stage stirred tubular continuous flow mixing reactor described in the second embodiment is used, wherein the continuous phase is pumped in from the first feed port 2 at a volume flow rate of 2.5 L / min, and the dispersed phase is pumped in from the second feed port 2 at a volume flow rate of 2.5 L / min; the entire multi-stage stirred tubular continuous flow mixing reactor is maintained at 0°C for reaction through a matching heat exchange jacket (outer jacket), the stirring rate is 200 rpm, and the product after the reaction is collected at the discharge port 3. After analysis, the substrate is completely converted, and it can be seen that there is obviously precipitated solid salt; the entire process conditions of the multi-stage stirred tubular continuous flow mixing reactor in the first embodiment can be continuously produced for more than 60 hours without clogging, while the conventional microchannel reactor in the comparative example, such as the Bayer valve-assisted micromixer, can only be maintained for less than 6 hours before a large pressure drop or clogging occurs, requiring the removal of the cleaning equipment.

[0088] Implementation Method 6: Reaction Process Test of Solid Slurry Feed

[0089] In the process of pharmaceutical chemistry and material chemistry, in addition to the situation mentioned in Implementation Example 5 where solids are produced during the reaction process, such as the reaction process in which an acid binding agent is involved and then a solid precipitate of an acid binding agent salt is produced, there are also process situations in which solids are directly fed to participate in the reaction. Conventional microchannel reactors generally require such solid reactants to be dissolved in a solvent to form a solution state, and then pumped into a continuous reaction system. In actual situations, the solubility of some solid reactants is too small to be adjusted to a solution state, and can only meet the slurry state.

[0090] The reaction slurry mixture obtained in the fifth embodiment is used, and a continuous feeding test is performed using the laboratory-level multi-stage stirred tubular continuous flow mixing reactor described in the first embodiment, wherein the stirring impeller 4 is a Brumakin-type stirring paddle.

[0091] The specific steps are as follows:

[0092] Step 1: collect 2 L of the slurry obtained in Embodiment 5 and place it in a prefabricated tank at room temperature with stirring to keep it in a slurry state for standby use (solid content is about 6 wt%);

[0093] Step 2: Use a constant pressure diaphragm pump suitable for slurry feeding to pump the slurry with a solid content of 6% into the system at a flow rate of 50 mL / min from the two feed ports 2 of the laboratory-level multi-stage stirred tubular continuous flow mixing reactor described in Embodiment 1 for cold model testing, and collect the corresponding slurry at a total flow rate of 100 mL / min at the discharge port 3. The process temperature is maintained at room temperature and the stirring rate is 150 rpm;

[0094] Step three: The material at the discharge port 3 is connected and collected into the slurry prefabrication tank connected to the pump feed port 2, so as to realize the circulation test of the slurry in the multi-stage stirred tubular continuous flow mixing reactor. The entire circulation process conditions can run continuously for 120 hours without clogging. However, the conventional microchannel reactor in the comparative example, such as the Corning heart-shaped micro-mixing reactor, can only be maintained for less than 10 minutes before a large pressure drop or clogging occurs, requiring equipment cleaning.

[0095] Example 2 (Multi-stage stirred tubular continuous microchannel reactor)

[0096] like Figure 1-3 As shown in Figures 6-8, based on Example 1, this embodiment adjusts the ratio of the axial length h1 of the single-stage stirring impeller 4 and the thickness b of the single-stage radial blocking component 5, as well as the diameter d1 of the stirring impeller 4, the diameter d of the radial blocking component 5 and the inner cavity diameter D of the cylindrical tubular shell 1, and the range of the characteristic index x=d1*D / (d*d) among the three, so as to make it more suitable for the synthesis process of micro-nanoparticles.

[0097] Specifically, the ratio of the axial length h1 of the single-stage stirring impeller 4 and the thickness b of the single-stage radial blocking component 5 is 5:1-1:10, preferably 5:1-1:3. In the synthesis process of micro-nano particles, it is necessary to accurately control the mixing degree of the reaction materials. The ratio of the axial length h1 of the single-stage stirring impeller 4 and the thickness b of the single-stage radial blocking component 5 is within the range of 5:1-1:10 (preferably 5:1-1:3). Compared with Example 1, the length of the stirring impeller 4 relative to the radial blocking component 5 is reduced. This gap still reduces the stirring intensity to a large extent. Although the stirring intensity is relatively weak, it has certain benefits for the growth stage of micro-nano particles. After the micro-nano particles have been formed, weak stirring can prevent the particles from agglomerating due to excessive shearing force. Because the micro-nano particles are small in size and high in surface energy, they are easy to adsorb and agglomerate with each other. Appropriate stirring intensity can reduce the probability of collision and agglomeration between particles while ensuring the mixing of materials.

[0098] At the same time, this ratio range can create an environment that is conducive to the growth of micro-nanoparticles. The appropriate h1 / b ratio enables the flow field in the reactor to ensure the mixing of reactants and enable the generated micro-nanoparticles to grow in a relatively stable environment.

[0099] The characteristic index x=d1*D / (d*d) among the diameter d1 of the impeller 4, the diameter d of the radial blocking member 5 and the inner diameter D of the cylindrical tubular housing 1 is in the range of 0.1-2, preferably 0.2-0.5. Firstly, this proportional relationship can ensure that there is enough space inside the reactor for the mixing of reactants and the growth of micro-nano particles. For example, in the synthesis of calcium carbonate nanoparticles, the slurry and the solution need to be fully mixed in a suitable space. The suitable range can ensure that the two reactants can fully contact in the reasonable flow field generated by the impeller 4 after entering the reactor, providing good conditions for the nucleation of micro-nano particles.

[0100] Secondly, for the synthesis of micro-nano particles, a smaller range (0.2-0.5) helps to form a relatively stable reaction area. Within this range, the impeller 4 rotates in a suitable space, and the flow field generated can fully mix the reactants in the local area without causing uneven dispersion of the reactants or too slow reaction due to excessive space. This is particularly important for nanoscale reactions, because the generation of micro-nano particles requires precise control of the concentration and contact time of the reactants, and a suitable reaction space can improve the selectivity and efficiency of the reaction.

[0101] The difference between it and Example 1 is as follows: Since the high viscosity system targeted by Example 1 has poor fluidity due to strong intermolecular forces, the design emphasizes generating sufficient shear force through a suitable structure to overcome the viscous force and promote overall mixing, so that the value of X is large, which can fully ensure the lateral area of ​​the stirring impeller 4 to promote stirring. At the same time, it also makes the size of the gap between the radial blocking component 5 and the inner wall of the cylindrical tubular shell 1 related. If solid materials are involved, this gap cannot be too small, and sufficient space is required for solid particles to pass smoothly. If it is micro-nano particles, the size of the gap (annular gap) can be appropriately reduced, which is closer to a microchannel reactor.

[0102] The size of the annular gap Dd is 50-1000 microns, preferably 150-500 microns.

[0103] The radial blocking component 5 in this embodiment can be a baffle or a block, both of which can be in the shape of a ring or a cylinder, or can be a structure with patterns carved on the axial cylinder. The above-mentioned patterns can enhance the mixing and heat transfer of materials between two adjacent stages of stirring impellers.

[0104] Specifically, first, in the micro-nano synthesis process, the microscopic mixing degree of the reactants plays a key role in the nucleation and growth of micro-nano particles. Compared with a single baffle, the radial blocking component 5 (baffle or block) with a pattern can enhance mixing at the microscale. The pattern structure can disrupt the laminar state of the fluid and generate more small-scale vortices and turbulence. For example, when the reactants for synthesizing micro-nano particles (such as metal salt solutions and precipitants) flow through the radial blocking component 5 with a pattern, these small-scale flow phenomena can enable the reactant molecules to fully contact in a smaller spatial range, which is conducive to the uniform nucleation of micro-nano particles. This is like creating more "encounter opportunities" for reactant molecules in the microscopic world, making the nucleation process of micro-nano particles more uniform and efficient.

[0105] Secondly, for the synthesis of micro-nanoparticles, the uniformity of mixing is extremely high. A single baffle may only provide a relatively simple flow field guidance, while a structure with patterns can enable the fluid to be fully mixed in different directions and positions when passing through the radial blocking component 5. This all-round mixing effect helps to ensure that the growth environment of each micro-nanoparticle is relatively consistent, thereby obtaining a micro-nanoparticle product with a narrower particle size distribution.

[0106] Finally, in the micro-nano synthesis process, many reactions are very sensitive to temperature. The patterned radial blocking component 5 can significantly improve the heat transfer efficiency, which is extremely beneficial for temperature control in the micro-nano synthesis process. The patterned structure increases the contact area between the radial blocking component 5 and the fluid, allowing heat to be transferred more quickly and evenly in the reaction system. Taking some nanomaterial synthesis reactions that need to be carried out at a specific temperature as an example, such as the synthesis of metal oxide nanoparticles by thermal decomposition, precise temperature control can be achieved through efficient heat transfer. The patterned structure is like laying a denser "heat exchange network" in the reactor, so that the reaction system can be better maintained within the required temperature range, avoiding the growth of micro-nano particles affected by local overheating or overcooling.

[0107] This embodiment specifically illustrates the reaction process suitable for manufacturing micro-nanoparticles through the following four implementation methods. The first three implementation methods are parameter ratios of reactors from different scales including laboratory, pilot and production level equipment; the latter are simulation results and actual experimental results of the reactor in different application scenarios, including the continuous reaction process for synthesizing micro-nanoparticles CaCO3.

[0108] Implementation Method 1: Laboratory-level Multi-stage Mixing

[0109] The number of stages is 5, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*5 / D = 5.2;

[0110] h1 / b=3, x=d1*D / (d*d)=0.6, annular gap (Dd) / 2=0.2mm=200 microns

[0111] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the baffle (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the baffle (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the baffle and the inner diameter of the cylindrical tubular housing 1.

[0112] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0113] The specific parameters are: inlet channel diameter wa = wb = 6.25mm, outlet channel diameter wc = 6.25mm,

[0114] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 50 mm, the baffle diameter (d) is 49.6 mm, the impeller 4 diameter (d1) is 29.5 mm, and the agitator shaft 7 diameter (d2) is 14 mm.

[0115] The axial length of the stirring impeller 4 (h1) is 30 mm, the height of the single-stage mixing unit (h2) is 52 mm, and the thickness of the baffle (b) is 10 mm.

[0116] Implementation Method 2: Pilot-Scale Multi-Stage Stirred Mixing Reactor

[0117] The number of stages is 8, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*8 / D = 9.6;

[0118] h1 / b=1, x=d1*D / (d*d)=0.956, annular gap (Dd) / 2=0.5mm=500 microns

[0119] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the stopper (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the stopper (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the stopper and the inner diameter of the cylindrical tubular housing 1.

[0120] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0121] The specific parameters are: inlet channel diameter wa = wb = 20mm, outlet channel diameter wc = 20mm,

[0122] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 300 mm, the block diameter (d) is 299 mm, the impeller 4 diameter (d1) is 285 mm, the agitator shaft 7 diameter (d2) is 80 mm,

[0123] The axial length of the stirring impeller 4 (h1) = 300 mm, the height of the single-stage mixing unit (h2) = 360 mm, and the thickness of the stopper (b) = 300 mm.

[0124] Implementation Method 3: Structural Parameters of Production-Level Multi-stage Stirring and Mixing Reactor

[0125] The number of stages is 10, and the ratio of the length (h2) of the cylindrical tubular housing 1 to the diameter of the inner cavity (D) = h2*10 / D = 11.25;

[0126] h1 / b=0.5, x=d1*D / (d*d)=0.985, annular gap (Dd) / 2=0.8mm=800 microns

[0127] References to the above corresponding letters: axial length of the stirring impeller 4 (h1); thickness of the stopper (b); diameter of the stirring impeller 4 (d1); inner diameter of the cylindrical tubular housing 1 (D); diameter of the stopper (d); characteristic index (x) among the diameter of the stirring impeller 4, the diameter of the stopper and the inner diameter of the cylindrical tubular housing 1.

[0128] It has two feed ports 2 and one discharge port 3, the first inlet channel diameter (wa); the second inlet channel diameter (wb) and the outlet channel diameter (wc)

[0129] The specific parameters are: inlet channel diameter wa = wb = 50mm, outlet channel diameter wc = 50mm,

[0130] The inner cavity diameter (D) of the cylindrical tubular housing 1 is 800 mm, the block diameter (d) is 798.4 mm, the impeller 4 diameter (d1) is 785 mm, the agitator shaft 7 diameter (d2) is 150 mm,

[0131] The axial length of the stirring impeller 4 (h1) = 700 mm, the height of the single-stage mixing unit (h2) = 850 mm, and the thickness of the stopper (b) = 1400 mm.

[0132] Embodiment 4 Continuous synthesis of micro-nano CaCO3 particles with narrow particle size distribution

[0133] In actual industrial production, kettle agitators are very prone to scaling, which places high demands on the equipment and makes it difficult to maintain and clean the equipment. In microchannel reactors, the concentration of reactants must not be too high, otherwise the heat release will be intense and the reactor will easily agglomerate and cause blockage.

[0134] In the seed generation reactor for the industrial production of calcium carbonate nanoparticles, nano calcium carbonate was successfully synthesized in a new reactor from two streams of materials: Ca(OH)2 slurry and Na2CO3 solution.

[0135] The synthesis process of CaC03 calcium carbonate nanoparticles was prepared by using Ca(OH)2 slurry and Na2C03 liquid phase reaction system, using the laboratory-level multi-stage stirred tubular continuous microchannel reactor described in Implementation Method 1, and the stirring impeller was a four-pitch blade impeller (45° PBT).

[0136] The specific steps are as follows:

[0137] Step 1: Dissolve Ca(OH)2 in deionized water at a concentration of 0.25 mol / L as a slurry dispersed phase. Dissolve Na2CO3 in deionized water at a concentration of 0.5 mol / L as a continuous phase; use the laboratory-level multi-stage stirred tubular continuous microchannel reactor described in Implementation Method 1;

[0138] Step 2: Ca(OH)2 slurry and Na2C03 solution are pumped into the mixing reactor from two feed ports 2 respectively under the action of a constant flow pump. The inlet volume flow rate of Ca(OH)2 is 80mL / min, the volume flow rate of Na2C03 solution is 40mL / min, the temperature is kept at room temperature, and the stirring speed of the impeller 4 is 120rpm. Ca(OH)2 reacts with Na2C03 to generate calcium carbonate. When the calcium carbonate in the water phase reaches saturation, the calcium carbonate generated by the reaction at the interface precipitates to form tiny calcium carbonate particles that flow out of the device with the continuous phase.

[0139] Step 3: Dilute the particles in a saturated solution of calcium carbonate and terminate the reaction. After ultrasonic dispersion, drop them onto a glass slide and dry them naturally at room temperature. The calcium carbonate particles with a particle size range of 55-85 nanometers and an average particle size of 65 nanometers are measured. Using the laboratory-grade multi-stage stirred tubular continuous microchannel reactor described in Implementation Method 1, the entire process conditions can be continuously produced for more than 105 hours without clogging, and the process and product quality are stable. In contrast, the Corning heart-shaped microreactor can only last for less than 6 hours before a large pressure drop or clogging occurs, requiring equipment cleaning, although the obtained particle size range and average particle size are not much different.

[0140] In summary, the present invention combines the respective advantages of a microchannel reactor and an active agitator, and on the basis of retaining the large specific surface area (surface area to volume ratio) of the microchannel device, adds active stirring (active stirring refers to the process of driving the stirring shaft 7 directly by a motor or by magnetic coupling to drive the multi-stage stirring impeller 4 to rotate, so that the materials entering the reactor are forced to mix under the action of the stirring impeller 4. Different from mixing methods such as natural convection or passive diffusion, active stirring is a positive mixing method with power input, which is a characteristic of an active agitator). At the same time, the high aspect ratio enables the reactor to have the advantage of efficient mixing and heat exchange of a microreactor, greatly enhancing the effect of heat and mass transfer, and broadening the scope of use of a microchannel reactor or a stirred reactor. Through CFD numerical simulation (refer to Appendix Figure 3) It can be found that after the third-stage mixing unit, the two streams of materials can be completely mixed. The stirring function of this product can ensure that the objects are quickly mixed after feeding and it is not easy for micro-nano particles to agglomerate or scale to cause excessive pressure drop or even blockage. The annular gap formed by the radial blocking component 5 enables the reactor to have the advantages of efficient mixing and heat exchange of a microreactor. The design of the radial blocking component 5 can also reduce inter-stage backmixing, ensure good mixing within the stage, and present an overall plug flow trend, thereby avoiding the shortcomings of a simple kettle agitator or a conventional microchannel reactor, such as insufficient stirring, the presence of a "dead zone", and insufficient heat exchange. There are problems of local "hot spots", back-mixing in the kettle and the "amplification" effect of the reactor, as well as problems of large pressure drop or easy clogging caused by the small size of the microchannel. In addition, through the different proportions of the ratio of the axial length of the single-stage stirring impeller and the thickness of the single-stage radial baffle plate and the diameter of the stirring impeller 4, the diameter of the radial baffle plate 5 and the inner cavity diameter of the cylindrical tubular shell 1 in Example 1 and Example 2, the reactor is suitable for high-viscosity systems or meets the process conditions of generating solids or even solid slurry (solid content can reach 20%) during the reaction process, and can also be well applied to the synthesis process of nanoparticles.

[0141] The present invention also provides a method for using the multi-stage stirred tubular continuous reactor:

[0142] Step 1: two or more materials are pumped into the reactor at a certain flow rate through a feed pump; Step 2: when the power source 6 is turned on at a certain speed, the power source 6 drives the rotation of the stirring shaft 7, and finally drives the rotation of the multi-stage stirring impeller 4, so that the materials pumped from the feed port 2 are mixed at the first stage through the stirring impeller 4;

[0143] Step 3: After the first baffle converges, the first-stage mixing unit is completed and reaches the next mixing unit, and so on, and then the mixing impellers 4 in other mixing units are mixed or reacted step by step;

[0144] Step 4: Finally, discharge through the discharge port 3.

[0145] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A multi-stage stirred tubular continuous reactor, characterized in that: The invention comprises a cylindrical tubular housing (1) with a large aspect ratio, wherein one end of the cylindrical tubular housing is provided with a feed inlet (2) and the other end of the cylindrical tubular housing is provided with a discharge outlet (3). The cylindrical tubular housing (1) is provided with a coaxial multi-stage stirring impeller (4) and a multi-stage radial blocking component (5) for separating the upper and lower stirring impellers (4). The multi-stage stirring impeller (4) is fixed on the same stirring shaft (7) driven by a power source (6). The first-stage stirring impeller (4) and the first-stage radial blocking component (5) form a first-stage mixing unit. The multi-stage mixing unit is finally formed by the multi-stage stirring impeller (4) and the multi-stage radial blocking component (5) and is fixed inside the cylindrical tubular housing (1). The diameter of the radial blocking component (5) is smaller than the inner cavity diameter of the cylindrical tubular housing (1). The ratio of the length of the cylindrical tubular housing (1) to the inner cavity diameter is greater than 5:1, the number of the mixing units consisting of the stirring impeller (4) and the radial blocking component (5) is greater than 3, and the number of the feed ports (2) is not less than 2.

2. A multi-stage stirred tubular continuous reactor according to claim 1, characterized in that: The single-stage radial blocking component (5) is a baffle, the ratio of the axial length h1 of the single-stage stirring impeller (4) to the thickness b of the single-stage radial blocking component (5) is 30:1-5:1, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller (4), the diameter d of the radial blocking component (5) and the inner cavity diameter D of the cylindrical tubular housing (1) is in the range of 0.5-5.

3. A multi-stage stirred tubular continuous reactor according to claim 2, characterized in that: The ratio of the axial length h1 of the single-stage stirring impeller (4) to the thickness b of the single-stage radial blocking component (5) is 30:1-20:1, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller (4), the diameter d of the radial blocking component (5) and the inner cavity diameter D of the cylindrical tubular housing (1) is in the range of 0.5-3.

4. A multi-stage stirred tubular continuous reactor according to claim 1, characterized in that: The single-stage radial blocking component (5) is a baffle or a block, the ratio of the axial length h1 of the single-stage stirring impeller (4) to the thickness b of the single-stage radial blocking component (5) is 5:1-1:10, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller (4), the diameter d of the radial blocking component (5) and the inner cavity diameter D of the cylindrical tubular housing (1) is in the range of 0.1-2.

5. A multi-stage stirred tubular continuous reactor according to claim 4, characterized in that: The ratio of the axial length h1 of the single-stage stirring impeller (4) to the thickness b of the single-stage radial blocking component (5) is 5:1-1:3, and the characteristic index x=d1*D / (d*d) among the diameter d1 of the stirring impeller (4), the diameter d of the radial blocking component (5) and the inner cavity diameter D of the cylindrical tubular housing (1) is in the range of 0.2-0.

5.

6. A multi-stage stirred tubular continuous reactor according to claim 4, characterized in that: The baffle plate and the block are in the shape of a ring or a cylinder, and a pattern structure is carved on the axial cylinders of the two.

7. A multi-stage stirred tubular continuous reactor according to claim 1, characterized in that: The stirring impeller (4) is a six-straight-blade open-type stirring impeller, a six-straight-blade disc turbine impeller, a screw-belt stirring impeller, a propeller stirring impeller, a Brumakin stirring impeller, a gear-shaped blade, a four-pitch-blade impeller or a disc turbine impeller.

8. A multi-stage stirred tubular continuous reactor according to claim 1, characterized in that: The outer side wall of the cylindrical tubular shell (1) is matched with a sleeve-type outer jacket to meet the process temperature control and heat exchange requirements.

9. A multi-stage stirred tubular continuous reactor according to claim 1, characterized in that: A bearing (8) is installed at the end of the cylindrical tubular housing (1); the stirring shaft (7) is sleeved in the bearing (8) and fixed to the inner ring of the bearing (8); the head of the stirring shaft (7) is connected to the power source (6) via a coupling (9); a spacer (10) is nested between the inner and outer rings of the bearing (8); and a support shaft (11) for supporting the radial blocking component (5) is arranged inside the cylindrical tubular housing (1).

10. The method for using the multi-stage stirred tubular continuous reactor according to any one of claims 1 to 9, characterized in that: The steps include: Step 1: Pump two or more materials into the reactor at a certain flow rate through a feed pump; Step 2: When the power source (6) is turned on at a certain speed, the power source (6) drives the stirring shaft (7) to rotate, and finally drives the multi-stage stirring impeller (4) to rotate, so that the material pumped in from the feed inlet is mixed at the first stage through the stirring impeller 4; Step 3: After the first layer of radial blocking components (5) are merged, the first stage of the mixing unit is completed and the next mixing unit is reached, and so on, and then the mixing impellers (4) in other mixing units are gradually passed through for mixing or reaction; Step 4: Finally, it is discharged through the discharge port (3).

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