Multi-stage stirring tube type continuous flow mixing reactor
By designing a multi-stage stirred tubular continuous flow mixing reactor, the problems of uneven mixing, local overheating, and clogging in existing stirred reactors and microreactors are solved, achieving efficient mixing and heat exchange of high-viscosity and solid slurries.
Patent Information
- Application Number
- CN202423250720.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-12-16
- Estimated Expiration
- 2034-12-27
AI Technical Summary
Existing stirred reactors suffer from problems such as insufficient mixing, local overheating, in-vessel backmixing, and scale-up effects in high-viscosity systems or solid-liquid two-phase processes. Furthermore, microreactors are prone to clogging, making it difficult to achieve efficient mixing and heat exchange.
A multi-stage stirred tube continuous flow mixing reactor is designed, which adopts a cylindrical tube shell with a large length-to-diameter ratio, coaxial multi-stage stirring impellers and radial blocking components. Combining the advantages of microchannel reactors and active stirrers, it achieves efficient mixing and heat exchange through multi-stage mixing units, avoids insufficient mixing and backmixing, and enhances heat and mass transfer effects.
It enables rapid mixing of high-viscosity systems and solid slurries, avoiding problems such as insufficient mixing, local overheating, and microreactor clogging, improving mixing uniformity and heat exchange efficiency, and is suitable for process conditions involving high-viscosity and solid slurry feed.
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Figure CN223669200U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of pharmaceutical chemical fine chemical equipment, more specifically, it relates to a multistage stirring pipe type continuous flow mixing reactor. BACKGROUND
[0002] In the prior art, for the mixing reaction process of high viscosity system or solid-liquid two-phase process, a strong stirring is usually arranged in the reactor or reaction kettle, and the structure of the stirrer is optimized to realize uniform mixing. For example, Wang Yinghui et al. (Chemical Industry and Engineering, 2023, 40 (2): 123-132.) measured the stirring power of four disc turbine paddle stirrers under the same conditions by using a laser Doppler velocimeter. Under the same mixing volume and power consumption, the stirring power required by the circular arc blade is the smallest compared with other types of blades, and the predicted value of numerical simulation and the experimental results have good consistency. Huang Cong et al. (Journal of Chemical Engineering of Universities, 2022, 36 (4): 554-561.) based on the pulse tracing method, with Na2SO4 saturated solution as the tracer, by measuring the conductivity change of three different structure blades of propeller, four inclined blade and airfoil blade at the outlet, it is found that the mixing time of four inclined blade and propeller is shorter, and the effect of promoting material mixing is larger. However, even if the structure of the above conventional stirring reactor is optimized, the following problems are difficult to avoid in the process of feeding and chemical reaction: 1) insufficient stirring and "dead zone" of stirring, which will cause local overmixing and lead to the generation of by-products. This phenomenon is almost impossible to avoid in conventional stirring reaction kettle; 2) heat exchange problem of conventional reaction kettle. Due to the limitation of specific surface area (surface area and volume ratio), the heat exchange efficiency of conventional stirring kettle is not high enough, and local overheating (hot spot) phenomenon often occurs. Local overheating often leads to the generation of by-products, which leads to the decrease of yield and selectivity; and if the large amount of heat generated by the reaction in production cannot be discharged in time, it will cause material overflow accident and even explosion. 3) Problem of back mixing in kettle: conventional single pot reaction often adopts the way of gradually adding reactants to prevent the reaction from being too violent, and in many reactions, the reaction time of reactants, products or intermediate transition state products under reaction conditions will lead to the generation of by-products. 4) Scale-up effect of conventional stirring reaction kettle: due to the limitation of the size characteristics (such as length-diameter ratio) of conventional reaction kettle, at the same time, with the gradual enlargement of reaction scale, the control of mass transfer and heat transfer becomes weaker, so the scale-up effect of stirring kettle will be very obvious.
[0003] In addition, compared with the conventional stirred reactor, the specific surface area is very large, the micro-reactor has extremely high mixing efficiency (radial complete mixing is achieved in the millisecond range), extremely strong heat exchange capacity (the heat transfer coefficient can reach 25,000 W / (m2·K)), and extremely narrow residence time distribution (almost no back mixing, basically close to plug flow). There are also attempts to use conventional micro-channel reactors for high-viscosity systems or continuous processes with solid-liquid two-phase processes, but due to the very small channel size of the process fluid in the micro-reactor (the characteristic size is usually between 10-1000 microns), actual operation will cause the system pressure drop to be too large or even the solid will cause blockage and thus cannot be used.
[0004] Therefore, in order to solve the above technical problems, the present application provides a multi-stage stirred pipe type continuous flow mixing reactor. Practical new content
[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a multi-stage stirred pipe type continuous flow mixing reactor.
[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a multi-stage stirred pipe type continuous flow mixing reactor, comprising a large-length-diameter-ratio cylindrical pipe type shell, one end of which is provided with a feed inlet, and the other end is provided with a discharge outlet, the inside of the cylindrical pipe type 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 form a first stage mixing unit, and the multi-stage stirring impeller and the multi-stage radial blocking component ultimately form a multi-stage mixing unit fixed in the inside of the cylindrical pipe type shell, the diameter of the radial blocking component is smaller than the inner cavity diameter of the cylindrical pipe type shell, the ratio of the length and the inner cavity diameter of the cylindrical pipe type shell is greater than 5:1, the number of mixing units composed of the stirring impeller 4 and the radial blocking component is greater than 3, and the number of feed inlets is not less than 2.
[0007] Among them, 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) between the stirring impeller diameter d1, the radial blocking component diameter d and the inner cavity diameter D of the cylindrical pipe type shell is in the range of 0.5-5.
[0008] 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) between the stirring impeller diameter d1, the radial blocking component diameter d and the inner cavity diameter D of the cylindrical pipe type shell is in the range of 0.5-3.
[0009] Preferably, the single-stage radial blocking component is a baffle.
[0010] Preferably, the stirring impeller is a six straight-blade open-type stirring paddle, a six straight-blade disc turbine paddle, a spiral stirring paddle, a propeller stirring paddle, a Brumagin stirring paddle, a gear-shaped blade, a four-inclined-blade paddle or a disc turbine paddle.
[0011] Preferably, a sleeve-type outer jacket is matched on the outer side wall of the cylindrical tube-type shell to meet the process temperature control and heat exchange requirements.
[0012] Preferably, bearings are mounted at the ends of the cylindrical tube-type shell, the stirring shaft is fixed in the bearings with the inner ring of the bearings, the head of the stirring shaft is connected with a power source through a shaft coupling, and a supporting shaft for supporting the radial blocking component is arranged inside the cylindrical tube-type shell.
[0013] Preferably, a spacer is nested between the inner and outer rings of the bearings, the spacer controls the axial gap between the inner and outer rings of the bearings, and the bearings are ensured to normally operate.
[0014] Compared with the prior art, the utility model has the following beneficial effects:
[0015] 1. The utility model combines the advantages of the micro-channel reactor and the active stirrer, increases the process conditions of the active stirring feeding on the basis of retaining the large specific surface area of the micro-channel equipment, and the high length-diameter ratio enables the reactor to have the advantages of the high-efficiency mixing and heat exchange of the micro-reactor, greatly strengthens the heat transfer and mass transfer effects, and thus solves the heat exchange problems of the conventional stirring reactor due to the insufficient surface area in the background technology.
[0016] 2. The utility model widens the use range of the micro-channel reactor or the stirring reactor, it can be found through CFD numerical simulation that the two materials can be completely mixed after the third-stage mixing unit, the stirring function of the product can ensure that the materials are quickly mixed after being fed and are not prone to the problems of the micro-nano particle agglomeration or fouling, the excessive pressure drop or even the blockage, the circulation gap formed by the radial blocking component enables the reactor to have the advantages of the high-efficiency mixing and heat exchange of the micro-reactor, the design of the radial blocking component also reduces the inter-stage back mixing, ensures the good mixing in the stage, and the overall trend is the plug flow, avoids the disadvantages of the simple tank-type stirring or the conventional micro-channel reactor, such as the insufficient stirring, the problems of the "dead zone", the back mixing in the tank and the "amplification" effect of the reactor, and the problems of the small channel size of the micro-reactor, the large pressure drop or the easy blockage, and thus solves the problems of the insufficient stirring, the "dead zone", the back mixing in the tank, the amplification effect of the conventional stirring reactor in the background technology and the small channel size, the easy blockage of the micro-reactor.
[0017] 3. The utility model discloses a single-stage stirring impeller axial length and single-stage radial baffle thickness ratio and the proportion of stirring impeller diameter, radial baffle diameter and cylindrical pipe shell inner chamber diameter design, make the reactor be suitable for high viscosity system or meet the process condition of solid, even solid slurry (solid content can reach 20%) feeding in the reaction process. BRIEF DESCRIPTION OF DRAWINGS
[0018] The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this application, illustrate embodiments of the utility model and serve to explain the utility model together with the foregoing specification. In the drawings:
[0019] Figure 1 It is the structure schematic drawing of the utility model (including A partial structure enlarged view and B partial cross section structure schematic drawing);
[0020] Figure 2 It is the kind schematic diagram of stirring impeller used in the utility model;
[0021] Figure 3 For marking Figure 1 The parameter of each structure (indicated the structure parameter of each component and key feature size) Figure 1
[0022] In the drawing: 1, cylindrical pipe shell;2, feed inlet;3, discharge port;4, stirring impeller;5, radial blocking component;6, power source;7, stirring shaft;8, bearing;9, shaft coupling;10, spacer;11, support shaft. DETAILED DESCRIPTION
[0023] As Figures 1-3 The utility model provides a kind of multistage stirring pipe type continuous flow mixing reactor, including the cylindrical pipe shell 1 of big length-diameter ratio, its one end is provided with feed inlet 2, other end is provided with discharge outlet 3, the inside of the cylindrical pipe shell 1 is provided with coaxial multistage stirring impeller 4 and the multistage radial blocking component 5 of separating upper and lower stirring impeller 4, multistage stirring impeller 4 is fixed on the same root by power source 6 driven stirring shaft 7, primary stirring impeller 4 and primary radial blocking component 5 constitute primary mixing unit, by multistage stirring impeller 4 and multistage radial blocking component 5 finally form multistage mixing unit fixed in the inside of cylindrical pipe shell 1, the end of cylindrical pipe shell 1 is equipped with bearing 8, stirring shaft 7 is fixed with the inner ring of bearing 8 by being set in bearing 8, and bearing 8 is rotated to support stirring shaft 7, and its head is connected with power source 6 by coupling 9, the inner and outer rings of bearing 8 are nested with spacer 10, can accurately control the axial gap between the inner and outer rings of bearing 8, ensure that bearing 8 is normally operated, the inside of the cylindrical pipe shell 1 is provided with support shaft 11 for supporting radial blocking component 5, and the diameter of radial blocking component 5 is less than the inner cavity diameter of cylindrical pipe shell 1.
[0024] The above-mentioned primary stirring impeller 4 and primary radial blocking component 5 constitute a primary mixing unit, which can form a multistage mixing unit fixed in the cylindrical pipe shell 1. When the stirring shaft 7 is directly driven by the motor or driven by the magnetic coupling (power source 6), the mixing function of the reactor can be realized.
[0025] One end of the cylindrical pipe shell 1 is formed with two or more feed inlets 2 (not less than two), and the other end is formed with one discharge outlet 3. Then, two or more materials are pumped into the pipe reactor at a certain flow rate by a feed pump (the materials can be gas or liquid). Then, when the power source 6 is turned on at a certain speed, the materials pumped from the feed inlet 2 can be mixed by the stirring impeller 4 at the first stage (active stirring), and then the first-stage mixing unit is completed after the flow is converged by the first layer of radial blocking components 5. Then, the materials are mixed or reacted by the other mixing units step by step, and finally, the system is discharged through the discharge outlet 3.
[0026] The number of mixing units composed of stirring impellers 4 and radial blocking components 5 is greater than 3, which is generally more than 10 in actual use. When the number of mixing units is greater than 3, multistage mixing of materials can be realized, the uniformity of mixing can be improved, the plug flow can be enhanced to reduce back mixing, and the reaction progress can be flexibly controlled. The number of feed inlets 2 is not less than two, which can meet the simultaneous feeding of multiple materials, facilitate the development of diversified reactions, and can also strengthen the mixing effect. Multiple material streams interact with each other and the flow ratio can be flexibly controlled to optimize the overall reaction process.
[0027] The types of stirring impeller 4 include, but are not limited to, six straight blade open stirring paddle, six straight blade disc turbine paddle, screw stirring paddle, propelling stirring paddle, Brumakin stirring paddle, gear-shaped blade, four inclined blade paddle (45°PBT), disc turbine paddle (Rushton), wherein the screw stirring paddle, propelling stirring paddle, four inclined blade paddle and Brumakin stirring paddle perform well in use, all of which can produce good material flow effect. Whether it is the simultaneous movement of the axial and circumferential directions of the screw stirring paddle, the high-efficiency axial flow generated by the propelling stirring paddle, or the complex flow field formed by the four inclined blade paddle (45°PBT) containing axial and circumferential flow, and the strong convection generated by the Brumakin stirring paddle, all of which help the material to flow and mix quickly in the reactor, reduce the stratification and aggregation of the material, and the stirring speed of the stirring impeller 4 can be controlled and adjusted, ranging from 0-1000 rpm, and through actual operation, the mixing effect is better at 200-1000 rpm, 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 extremely easy to appear the condition of not being fully mixed, the length of the cylindrical tubular shell 1 to the inner cavity diameter is preferably greater than 8:1, or even 10:1, so as to fully ensure the complete mixing of the material, wherein the radial blocking component is a baffle.
[0028] Further, a tubular outer jacket is matched on the outer side wall of the cylindrical tubular shell 1 to meet the process temperature control and heat exchange requirements.
[0029] And 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 30:1-5:1, preferably 30:1-20:1 (sufficient to ensure the axial length of the stirring impeller 4), which can ensure that the stirring impeller 4 has sufficient length to produce effective stirring in each stage of the mixing unit. If the ratio of h1 / b is too small, the stirring impeller 4 is relatively short, and the stirring effect is limited, which is difficult to overcome the viscous force of the high-viscosity system, and cannot well disperse the solid or solid slurry, for example, when h1 is too short, it may not be able to form sufficient vortex and shear force to mix high-viscosity fluid or suspend solids. If the ratio is too large, it may lead to an unreasonable structure of the mixing unit, affecting the flow path and residence time of the material in the unit, which is not conducive to improving the mixing efficiency, and the characteristic index x=d1*D / (d*d) of the diameter d1 of the stirring impeller 4, the diameter d of the radial blocking component 5, and the diameter D of the inner cavity of the cylindrical tubular shell 1 is in the range of 0.5-5, preferably 0.5-3 (sufficient to ensure the axial size of the stirring impeller 4), which ensures the 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 in the appropriate range, the stirring impeller 4 has a suitable transverse area, so that when the stirring impeller 4 rotates, a flow field with sufficient strength can be generated to fully stir the high-viscosity fluid, and the radial blocking component 5 and the cylindrical tubular shell 1 are also associated, avoiding a small annular gap (the difference between the diameter D of the inner cavity 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 the material to pass through, so that the generated solid particles have enough space to pass through, and the channel will not be blocked due to the narrow space. This is crucial for processes that produce solids during the reaction process, as blockage can cause the reaction to stop, and the present application can effectively avoid this situation to achieve continuous operation of the solid production process, so that the present application is particularly suitable for high-viscosity systems or process conditions that produce solids during the reaction process, or even solid slurry (solid content up to 20%) feed.
[0030] Wherein the size of the annular gap D-d is not less than 300 microns, preferably not less than 1000 microns.
[0031] The present application is particularly suitable for high-viscosity systems or process conditions that produce solids during the reaction process, or even solid slurry feed, which is illustrated by the following six embodiments. The first three embodiments are the parameter matching of the reactor from different scales including laboratory, pilot and production level equipment; the last three embodiments are the simulation results and actual experimental results of the reactor in different application scenarios, including continuous mixing of high-viscosity systems and continuous process applications of solid production, and continuous reaction process of solid slurry feed.
[0032] Embodiment 1, laboratory scale multi-stage stirring
[0033] 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) is = h2*5 / D = 5.2.
[0034] h2*5 / D = 5.2.
[0035] h1 / b = 15, x = d1*D / (d*d) = 0.957, and the annular gap (D-d) / 2 = 0.2 mm = 750 microns.
[0036] The above references to the corresponding letters are: the axial length (h1) of the stirring impeller 4; the baffle thickness (b); the diameter (d1) of the stirring impeller 4; the diameter (D) of the inner cavity of the cylindrical tubular housing 1; the diameter (d) of the baffle; and the characteristic index (x) between the diameter of the stirring impeller 4, the diameter of the baffle, and the diameter of the inner cavity of the cylindrical tubular housing 1.
[0037] There are two feed inlets 2 and one discharge outlet 3, and the diameters of the first inlet channel (wa), the second inlet channel (wb), and the outlet channel (wc) are
[0038] The specific parameters are: wa = wb = 6.25 mm, wc = 6.25 mm,
[0039] The diameter (D) of the inner cavity of the cylindrical tubular housing 1 is 50 mm, the diameter (d) of the baffle is 48.5 mm, the diameter (d1) of the stirring impeller 4 is 45 mm, and the diameter (d2) of the stirring shaft 7 is 14 mm,
[0040] The axial length (h1) of the stirring impeller 4 is 30 mm, the height (h2) of the single-stage mixing unit is 52 mm, and the baffle thickness (b) is 2 mm.
[0041] Embodiment 2, pilot scale multi-stage stirring mixing reactor
[0042] 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) is = h2*8 / D = 9.6.
[0043] h1 / b = 20, x = d1*D / (d*d) = 0.956, and the annular gap (D-d) / 2 = 2 mm = 2000 microns.
[0044] The above references to the corresponding letters are: the axial length (h1) of the stirring impeller 4; the baffle thickness (b); the diameter (d1) of the stirring impeller 4; the diameter (D) of the inner cavity of the cylindrical tubular housing 1; the diameter (d) of the baffle; and the characteristic index (x) between the diameter of the stirring impeller 4, the diameter of the baffle, and the diameter of the inner cavity of the cylindrical tubular housing 1.
[0045] with two feed inlets 2 and one outlet 3, first inlet channel diameter (wa); second inlet channel diameter (wb) and outlet channel diameter (wc)
[0046] The specific parameters are: inlet channel diameter wa=wb=20 mm, outlet channel diameter wc=20 mm,
[0047] Cylindrical tubular housing 1 inner cavity diameter (D) = 300 mm, baffle diameter (d) = 296 mm, stirring impeller 4 diameter (d1) = 285 mm, stirring shaft 7 diameter (d2) = 80 mm,
[0048] Stirring impeller 4 axial length (h1) = 300 mm, single-stage mixing unit height (h2) = 360 mm, baffle thickness (b) = 15 mm.
[0049] Embodiment three, production level multi-stage stirring mixing reactor structure parameters
[0050] Stage number is 10 stages, the ratio of the length (h2) and the inner cavity (D) diameter of the cylindrical tubular housing 1 = h2*10 / D = 9.38;
[0051] h1 / b = 25, x = d1*D / (d*d) = 1.00, circular ring gap (D-d) / 2 = 5 mm = 5000 microns
[0052] The above corresponding letter reference: stirring impeller 4 axial length (h1); baffle thickness (b); stirring impeller 4 diameter (d1); cylindrical tubular housing 1 inner cavity diameter (D); baffle diameter (d); the characteristic index (x) between stirring impeller 4 diameter, baffle diameter and cylindrical tubular housing 1 inner cavity diameter.
[0053] with two feed inlets 2 and one outlet 3, first inlet channel diameter (wa); second inlet channel diameter (wb) and outlet channel diameter (wc)
[0054] The specific parameters are: inlet channel diameter wa=wb=50 mm, outlet channel diameter wc=50 mm,
[0055] Cylindrical tubular housing 1 inner cavity diameter (D) = 800 mm, baffle diameter (d) = 790 mm, stirring impeller 4 diameter (d1) = 785 mm, stirring shaft 7 diameter (d2) = 150 mm,
[0056] Stirring impeller 4 axial length (h1) = 625 mm, single-stage mixing unit height (h2) = 750 mm, baffle thickness (b) = 25 mm.
[0057] Embodiment four numerical simulation of high viscosity fluid mixing effect
[0058] Mixing of high viscosity fluid is a basic unit operation in industrial production, which is widely used in rubber, chemical, food, pharmaceutical and other fields. In industrial production, it is generally considered that the fluid with viscosity less than 5 Pa·s in the mixing equipment is low viscosity fluid, the fluid with viscosity of 5-50 Pa·s is medium viscosity fluid, the fluid with viscosity of 50-500 Pa·s is high viscosity fluid, and the fluid with viscosity greater than 500 Pa·s is super high viscosity fluid. Four different mass fraction of syrup solution is used as stirring material, and the main parameters such as density and viscosity are obtained by actual measurement, as shown in Table 1.
[0059] Table 1 Rheological properties of stirring medium
[0060]
[0061] In order to quantitatively evaluate the mixing degree of medium, the mixing degree is quantified and analyzed by calculating the variance of two fluids in the stirrer, and the mixing index (MI) value is defined as:
[0062]
[0063] In the formula, σ is the standard deviation of the mass fraction of the fluid along the flow direction at any cross section, σ max is the maximum standard deviation. The larger the mixing index is, the better the mixing effect is. 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.
[0064]
[0065] In the formula, N refers to the number of fluid mass fraction sampling points at a cross section along the flow direction, c i is the mass fraction of the fluid at the i th sampling point, is the expected value of the fluid mass fraction after mixing, that is, the best mixing mass fraction (in this paper, the value is 0.5).
[0066] In the process of stirring and mixing of high viscosity fluid, the reactor stage is one of the key factors affecting the flow pattern and mixing effect of the flow field. With the increase of the reactor stage, the mixing effect of the fluid is also enhanced, but the energy consumption of the system is also increased 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 stage in actual application.
[0067] First in the low number of reactors, the flow field is relatively simple, high viscosity fluid in the reactor under the action of the formation of the blade as the center of the localized vortex, due to the high viscosity of the fluid, the flow field shows a high degree of non-uniformity, the flow rate gradient of the fluid changes more slowly. With the increase of the number of reactor, more shear layer is introduced by multi-stage reactor, which drives the flow of the surrounding flow dead zone liquid, forming some smaller vortex structure, at this time the high viscosity fluid is more uniformly dispersed and mixed. Fluid flow through the baffle between the adjacent two levels of extrusion and stretching, this separation and reorganization process intensifies the imbalance between the collision of fluid, helps to overcome the cohesive force of high viscosity fluid, improve the mixing effect.
[0068] Embodiment five, the application of the solid process
[0069] The deacid reagent is an organic weak base, and commonly used ones include pyridine, triethylamine and diisopropyl ethylamine, etc. Triethylamine is a weak base with a pka (conjugate acid) of 10.75, and is commonly used as a deacid reagent. If HCl is generated in the system, a hydrochloride salt of triethylamine will be formed. The hydrochloride salt of triethylamine is generally insoluble in organic solvents. If the product is easily soluble in the reaction solvent, then triethylamine is selected as the deacid reagent at this time, and the hydrochloride salt of triethylamine can be directly separated from the product by the difference in solubility.
[0070] However, in actual application, especially in the development of conventional micro-channel reaction process, the selection of the above system will face the problem of clogging of the reaction equipment by the precipitated hydrochloride salt of triethylamine. Therefore, the multi-stage stirring pipe type continuous flow mixing reactor developed by the present patent can avoid clogging while realizing the continuous operation of the solid process.
[0071] The pilot-scale multi-stage stirring pipe type continuous flow mixing reactor described in embodiment two is adopted, wherein the stirring impeller 4 is a six straight blade open stirring paddle.
[0072] The specific steps are as follows:
[0073] Step one: dissolve the substrate chalcone in anhydrous THF with a concentration of 1 mol / L, then add an equivalent of triethylamine as the continuous phase; at the same time, dissolve acetyl chloride in anhydrous THF with a concentration of 1 mol / L as the dispersed phase. Both kinds of reaction solutions are stored in a 0℃ low temperature bath for use;
[0074] Step two: use the multi-stage stirred tubular continuous flow mixing reactor described in embodiment two, where the continuous phase is pumped from the first feed port 2 at a volume flow rate of 2.5 L / min, and the dispersed phase is pumped 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 kept at 0°C by the matching heat exchange jacket (outer jacket) for reaction, the stirring rate is 200 rpm, and the product after reaction is collected at the discharge port 3 for analysis; complete conversion of the substrate is observed, and obvious solid salt precipitation can be seen; the entire process condition of the multi-stage stirred tubular continuous flow mixing reactor in embodiment one can be continuously produced for more than 60 hours without plugging, while the conventional microchannel reactor such as the valve-assisted micromixer in the comparative example can only be maintained for less than 6 hours before a large pressure drop or plugging occurs, requiring the device to be disassembled and cleaned.
[0075] Embodiment six, reaction process test of solid slurry feed
[0076] In the process of pharmaceutical and material chemical industry, in addition to the reaction process mentioned in embodiment five in which solid is produced during the reaction, such as the reaction process in which a solid precipitate of a salt of a base is produced after the participation of a base, there are also processes in which a solid is directly fed into the reaction. Generally, the conventional microchannel reactor needs to dissolve such solid reactants into a solution state in a solvent and then pump them into the continuous reaction system. However, in actual cases, the solubility of some solid reactants is too small to be adjusted to a solution state, and only a slurry state can be achieved.
[0077] The reaction slurry mixture obtained in embodiment five is used for continuous feeding test by using the laboratory-scale multi-stage stirred tubular continuous flow mixing reactor described in embodiment one, wherein the stirring impeller 4 is a Brumakin stirring paddle.
[0078] The specific steps are as follows:
[0079] Step one: 2L of the slurry obtained in embodiment five is collected and placed in a pre-prepared tank with stirring at room temperature to maintain the slurry state (solid content is about 6wt%);
[0080] Step two: the 6% solid-containing slurry is pumped into the system at a flow rate of 50 mL / min from the two feed ports 2 of the laboratory-scale multi-stage stirred tubular continuous flow mixing reactor described in embodiment one by using a constant-pressure diaphragm pump suitable for slurry feeding, and the corresponding slurry is collected at the discharge port 3 at a total flow rate of 100 mL / min; the process temperature is kept at room temperature, and the stirring rate is 150 rpm;
[0081] Step three: the material of the outlet 3 is connected to the slurry pre-preparation tank of the pump inlet 2 to realize the circulation test of the slurry in the multi-stage stirring pipe type continuous flow mixing reactor. The whole circulation process can be continuously operated for 120 hours without blockage, while the conventional micro-channel reactor such as the Corning heart-shaped micro-mixing reactor in the comparative example can only maintain less than 10 minutes to produce a large pressure drop or blockage, and the equipment needs to be cleaned.
[0082] In summary, the present application combines the advantages of micro-channel reactors and active mixers. On the basis of retaining the large specific surface area (surface area to volume ratio) of micro-channel equipment, the active stirring (active stirring refers to the process of directly driving or magnetically coupling the stirring shaft 7 to drive the multi-stage stirring impeller 4 to rotate, so that the material entering the reactor is forced to mix under the action of the stirring impeller 4. Unlike natural convection or passive diffusion mixing methods, active stirring is a powered and active mixing method, which is the characteristic of active mixers), and the high aspect ratio makes the reactor have the advantages of high-efficiency mixing and heat exchange of micro-reactors, greatly strengthening the heat and mass transfer effect, widening the use range of micro-channel reactors or stirring reactors, and through CFD numerical simulation, it is found that after the third mixing unit, the two materials can be completely mixed. The stirring function of the product can ensure that the object is mixed quickly after feeding and is not easy to cause micro-nano particle agglomeration or fouling, resulting in excessive pressure drop or even blockage. The annular flow gap formed by the radial blocking part 5 makes the reactor have the advantages of high-efficiency mixing and heat exchange of micro-reactors, and the design of the radial blocking part 5 can also reduce the inter-stage back mixing and ensure good mixing in the stage, thereby avoiding the shortcomings of pure kettle type stirrers or conventional micro-channel reactors, such as insufficient stirring, existence of "dead zone", insufficient heat exchange, existence of local "hot spot", problems of back mixing in the kettle, "amplification" effect of the reactor, and problems of large pressure drop or easy blockage caused by too small micro-channel size. And through the proportion design of the ratio of the axial length of the single-stage stirring impeller and the thickness of the single-stage radial baffle in Example 1 and Example 2, as well as the ratio of the diameter of the stirring impeller 4, the diameter of the radial baffle 5 and the diameter of the inner cavity of the cylindrical pipe type shell 1, the reactor is suitable for high-viscosity systems or process conditions where solid or even solid slurry (solid content up to 20%) is produced during the reaction process.
[0083] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form; any person skilled in the art can smoothly implement the present application according to the drawings shown in the specification and the above description; however, any person skilled in the art can make slight changes, modifications and equivalent changes of the present application within the scope of the technical scheme of the present application, and the equivalent embodiments of the present application are still within the protection scope of the technical scheme of the present application.
Claims
1. A multi-stage stirred tubular continuous flow mixed reactor characterized by: The application relates to a cylindrical tubular shell (1) with a large length-diameter ratio, which is provided with a feeding port (2) at one end and a discharging port (3) at the other end, and is internally provided with coaxial multi-stage stirring impellers (4) and multi-stage radial blocking components (5) for separating the upper and lower stirring impellers (4), the multi-stage stirring impellers (4) are fixed on the same stirring shaft (7) driven by a power source (6), a stage stirring impeller (4) and a stage radial blocking component (5) form a stage mixing unit, and finally a multi-stage mixing unit is formed by the multi-stage stirring impellers (4) and the multi-stage radial blocking components (5) and is fixed in the cylindrical tubular shell (1), the radial blocking component (5) has a diameter smaller than the inner cavity diameter of the cylindrical tubular shell (1), the length-diameter ratio of the cylindrical tubular shell (1) is greater than 5:1, the number of the mixing units formed by the stirring impellers (4) and the radial blocking components (5) is greater than 3, and the number of the feeding ports (2) is not less than 2. The axial length h1 of the single-stage stirring impeller (4) and the thickness b of the single-stage radial blocking component (5) have a ratio of 30:1-5:1, 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) have a characteristic index x = d1*D / (d*d) in the range of 0.5-5.
2. A multi-stage stirred pipe continuous flow mixed reactor according to claim 1, characterized in that: The axial length h1 of the single-stage stirring impeller (4) and the thickness b of the single-stage radial blocking component (5) have a ratio of 30:1-20:1, 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) have a characteristic index x = d1*D / (d*d) in the range of 0.5-3.
3. The multi-stage stirred pipe continuous flow mixed reactor according to claim 1, characterized in that: The single-stage radial blocking component (5) is a baffle.
4. The multi-stage stirred pipe continuous-flow mixed reactor according to claim 1, characterized in that: The stirring impeller (4) is a six-straight-leaf open stirring paddle, a six-straight-leaf disc turbine paddle, a spiral stirring paddle, a propelling stirring paddle, a Brumakin stirring paddle, a gear-shaped blade, a four-inclined-leaf paddle or a disc turbine paddle.
5. The multi-stage stirred pipe continuous flow mixed reactor according to claim 1, characterized in that: A sleeve type outer jacket is matched on the outer side wall of the cylindrical tubular shell (1) to meet the process temperature control and heat exchange requirements.
6. A multi-stage stirred pipe continuous flow mixed reactor according to claim 4, wherein: The end of the cylindrical tubular shell (1) is provided with a bearing (8), the stirring shaft (7) is sleeved in the bearing (8) and is fixed with the inner ring of the bearing (8), the head of the stirring shaft (7) is connected with the power source (6) through a shaft coupling (9), and the cylindrical tubular shell (1) is internally provided with a supporting shaft (11) for supporting the radial blocking component (5).
7. A multi-stage stirred pipe continuous flow mixed reactor according to claim 6, wherein: A spacer (10) is nested between the inner and outer rings of the bearing (8).