WO2005120690A1 - Microstructure designs for optimizing mixing and pressure drop - Google Patents

Microstructure designs for optimizing mixing and pressure drop Download PDF

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Publication number
WO2005120690A1
WO2005120690A1 PCT/EP2005/006265 EP2005006265W WO2005120690A1 WO 2005120690 A1 WO2005120690 A1 WO 2005120690A1 EP 2005006265 W EP2005006265 W EP 2005006265W WO 2005120690 A1 WO2005120690 A1 WO 2005120690A1
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WO
WIPO (PCT)
Prior art keywords
mixer
range
mixing
obstacle
looμm
Prior art date
Application number
PCT/EP2005/006265
Other languages
French (fr)
Inventor
Pierre Woehl
Jean-Pierre Themont
Yann Nedelec
Original Assignee
Corning Incorporated
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Corning Incorporated filed Critical Corning Incorporated
Priority to CN2005800189807A priority Critical patent/CN1964777B/en
Priority to JP2007526312A priority patent/JP2008501517A/en
Publication of WO2005120690A1 publication Critical patent/WO2005120690A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40—Static mixers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
    • B01F25/3131—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit with additional mixing means other than injector mixers, e.g. screens, baffles or rotating elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
    • B01F25/3132—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit by using two or more injector devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/30—Injector mixers
    • B01F25/31—Injector mixers in conduits or tubes through which the main component flows
    • B01F25/313—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit
    • B01F25/3132—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit by using two or more injector devices
    • B01F25/31324—Injector mixers in conduits or tubes through which the main component flows wherein additional components are introduced in the centre of the conduit by using two or more injector devices arranged concentrically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40—Static mixers
    • B01F25/42—Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions
    • B01F25/43—Mixing tubes, e.g. wherein the material is moved in a radial or partly reversed direction
    • B01F25/433—Mixing tubes wherein the shape of the tube influences the mixing, e.g. mixing tubes with varying cross-section or provided with inwardly extending profiles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F33/00—Other mixers; Mixing plants; Combinations of mixers
    • B01F33/30—Micromixers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40—Static mixers
    • B01F25/42—Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions
    • B01F25/43—Mixing tubes, e.g. wherein the material is moved in a radial or partly reversed direction
    • B01F25/431—Straight mixing tubes with baffles or obstructions that do not cause substantial pressure drop; Baffles therefor
    • B01F25/4317—Profiled elements, e.g. profiled blades, bars, pillars, columns or chevrons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
    • B01F25/40—Static mixers
    • B01F25/42—Static mixers in which the mixing is affected by moving the components jointly in changing directions, e.g. in tubes provided with baffles or obstructions
    • B01F25/43—Mixing tubes, e.g. wherein the material is moved in a radial or partly reversed direction
    • B01F25/431—Straight mixing tubes with baffles or obstructions that do not cause substantial pressure drop; Baffles therefor
    • B01F25/43197—Straight mixing tubes with baffles or obstructions that do not cause substantial pressure drop; Baffles therefor characterised by the mounting of the baffles or obstructions
    • B01F25/431971—Mounted on the wall
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S366/00—Agitating
    • Y10S366/03—Micromixers: variable geometry from the pathway influences mixing/agitation of non-laminar fluid flow

Definitions

  • This invention relates generally to micro reactor systems and devices and more particularly to a class of designs for mixers used within micro reactor systems.
  • liquids in a path are necessary to create adequate liquid flow in a micro reactor system or more particularly, in a mixer design or module within a micro reactor system.
  • a source of reactants or a least a plurality of fluid connections for delivering reactants at an injection zone for upstream flow.
  • liquids in the prior art include water, aqueous and organic liquid solutions.
  • mixers of several types to generate mixing in micro systems. Whatever mixing solution is chosen, the mixer may be implemented within a complete micro system. The required attributes for the mixers are therefore extended beyond mixing efficiency, whereby mixer dimensions can preferably be changed to affect pressure drop, but not affect mixing efficiency or at least have a minimum effect on mixing efficiency.
  • FIG. 1 a typical split and recombine solution is shown in FIG. 1 and described in US Patent Number 5,904,424 Al entitled " Device for Mixing Small Quantities of Liquids".
  • the inlet reactant streams are separated and recombined in a multi-layered structure.
  • IMM mixing split-reco bine concept of caterpillar mixers includes two unmixed fluid streams divided such that two new regions are formed and are further down recombined. All four regions are ordered alternatively next to each other such that the original geometry is re-established.
  • three-dimensional flows that represent chaotropic solutions. These designs solve the problem of mixing by creating a transverse flow without requiring the use of moving mixer elements.
  • FIG. 2 Another similar prior art chaotropic mixer can be found for instance, in International Publication Number WO03/011443A2, entitled, * Laminar Mixing Apparatus and Methods" assigned to the President and Fellows of Harvard College.
  • the helical flow is created by weak modulations of the shape of the walls of the channel, or by grooves defined on the channel wall allowing mixing of a fluid with a Reynolds number of less than 100 thereby capably mixing a fluid flowing in the micro-regime.
  • FIG. 2 A similar prior art structure is shown in FIG. 2.
  • CPC Cellular Process Chemistry
  • a new approach is needed that preferably overcomes the disadvantages of any of the prior art solutions above that provide optimal pressure drop by tuning inner dimensions; localized liquid flow at geometric obstacles and restrictions in the path structure; mixing generated in the path structure via obstacles and by reducing local dimensions; fully three dimensional flow between obstacles; control at the initial contact region at injection; and robustness of efficiency with respect to fluids.
  • fluid is herein defined as including miscible and immiscible liquid-liquids, gas-liquids and solids.
  • a class of designs is provided for a mixer in microreactors where the design principle includes an injection zone with one or more interfaces and cores where two or more fluids achieve initial upstream contact and an effective mixing zone containing a series of mixer elements in the flow path and wherein each mixer element is designed with a chamber at the end in which an obstacle such as a pillar is placed to reduce the typical inner dimension and an optional restriction in the channel segment.
  • the preferred embodiment can have many permutations in its design whereby for instance, it can also include an injection-mixing-injection concept where additional fluid-mixing is done further downstream.
  • One embodiment of the present invention relates to a mixer apparatus having at least one injection zone of a continuous flow path where a plurality of fluids make initial contact and at least one mixer element in the flow path, the at least one mixer element efficiently mixing the fluids through the path.
  • Each one of the mixer elements includes a channel segment, a chamber disposed at ends of the channel segment and each chamber further includes at least one obstacle.
  • Another embodiment of the present invention relates to at least one obstacle situated anywhere in the flow path.
  • the channel segment further including at least one restriction, the segment having a radius in the range of lOO ⁇ m to 5000 ⁇ m, height in the range of lOO ⁇ m to 5000 ⁇ m, a width in the range of lOO ⁇ m to lOOOO ⁇ m, and a length in the range of 200 ⁇ m to lOOOO ⁇ m and the restriction having a a height in the range of lOO ⁇ m to 5000 ⁇ m and a width in the range of 50 ⁇ m to 2500 ⁇ m.
  • Another embodiment of the present invention relates to inner dimensions of the chamber being reduced in the presence of the at least one obstacle and wherein increased dimensions of said obstacle increase the mixing efficiency.
  • Another embodiment of the present invention relates to the at least one obstacle having any geometry with a radius in the range of 50 ⁇ m to 4000 ⁇ m and a height of lOO ⁇ m to 5000 ⁇ m and wherein the inner dimensions of the chamber in the presence of the at least one obstacle are further characterized by a radius in the range of lOO ⁇ m to 5000 ⁇ m, a perimeter from 600 ⁇ m to 30mm, a surface area from 3mm 2 to 80mm 2 , a volume from 0.3mm 3 to 120mm 3 , and a height in the range between lOO ⁇ m and 5000 ⁇ m.
  • Another embodiment of the present invention relates to the at least one injection zone having at least one core and fluids in the at least one core flow through and towards a plurality of interfaces.
  • Another embodiment of the present invention relates to the mixer apparatus being embedded in a micro reactor system, the system including at least one of the following: a reactant fluid source, a pump, a dwell time zone and an output filter.
  • a reactant fluid source e.g., a gas, a gas, or a gas.
  • a pump e.g., a pump
  • a dwell time zone e.g., a dwell time zone
  • an output filter e.g., a mixer apparatus, preferably made of glass, ceramic or glass-ceramic substrate materials.
  • FIG. 1 is an example of a prior art split and recombine mixer.
  • FIG. 2 is an example of a prior art chaotropic mixer.
  • FIG.3 is an example of a prior art slug and decompression mixer.
  • FIG. 4 is a three-dimensional schematic view of a mixer in accordance with a preferred embodiment of the present invention.
  • FIG. 5 is a cross-sectional view of FIG. 4 in the center of a mixer post in accordance with a preferred embodiment of the present invention.
  • FIGs. 6a and 6b are top views of layers of the mixer design in accordance with a preferred embodiment of the present invention.
  • FIGs. 7a and 7b show typical dimensions of the mixer designs of FIGs. 6a and 6b in accordance with a preferred embodiment of the present invention.
  • FIG. 8 is a top view of alternate mixer designs with increased dimensions in accordance with a preferred embodiment of the present invention.
  • FIG. 8a shows a multiple core injection zone in accordance with an alternate preferred embodiment of the present invention.
  • FIGs. 9-11 are plots of pressure drop and mixing quality of various mixer designs of FIG. 8 having varying dimensions in accordance with a preferred embodiment of the present invention.
  • FIG. 12 shows a top view of a mixer embedded in a mixer reactor structure in accordance with a preferred embodiment of the present invention.
  • FIG. 13 shows a block diagram of the mixer of FIG. 12 in a micro reactor system in accordance with a preferred embodiment of the present invention.
  • FIG. 4 a three-dimensional view of mixer 400 is shown in accordance with a preferred embodiment of the present invention to include an injection zone 410 where two or more fluids or reactants (not shown) would make initial contact and flow upstream as indicated at arrow 420.
  • a series of mixer elements 430 are shown to include: 1.) fairly rectangular channel segments 435 (with slightly rounded corners); and 2.) a chamber 440 at each end of the channel segment, with an obstacle 450 positioned inside of the chamber in accordance with a preferred embodiment of the present invention of the mixer 400.
  • the obstacle 450 is a cylindrical pillar or post placed within chamber 440, thereby reducing the inner dimension 442 of the chamber 440.
  • a restriction 460 that is dimple-like may be present on one or both sides of segment 435.
  • an injection-mixing-injection layout (not shown) is provided where additional fluid-mixing is accomplished further downstream.
  • the obstacle 450 dimension ranges include: a radius or related dimension of 50 ⁇ m to 4000 ⁇ m and a height of lOO ⁇ m to 5000 ⁇ m.
  • Channel segment 435 ranges include: a radius of lOO ⁇ m to 5000 ⁇ m, height of lOO ⁇ m to 5000 ⁇ m, a width of lOO ⁇ m to lOOOO ⁇ m, and a length of 200 ⁇ m to lOOOO ⁇ m in accordance with the preferred embodiment of the present invention.
  • Restriction 460 dimension ranges include: a width of 50 ⁇ m to 2500 ⁇ m and a height of lOO ⁇ m to 5000 ⁇ m in accordance with the preferred embodiment of the present invention.
  • the inner dimension of the chamber 442 in the presence of the obstacle 450 has a radius in the range of lOO ⁇ m to 5000 ⁇ m, with a perimeter ranging from 600 ⁇ m to 30mm, a surface from 3mm 2 to 80mm 2 , and a volume from 0.3mm 3 to 120mm 3 (with heights between lOO ⁇ m and 5000 ⁇ m) in accordance with the preferred embodiment of the present invention.
  • FIG. 5 shows a cross-section view of an obstacle 450, shown as a pillar in FIG. 4, in accordance with the present invention.
  • the pillar 450 creates a tortuous patfi for the liquids or reactants to flow through, thereby creating adequate flow which may include accelerating the flow of the liquids or reactants locally, due to reduced inner dimensions.
  • FIG. 5 depicts this tortuous flow within the cavity 512 of chamber 440 via arrows 510 and 520.
  • the Reynolds numbers water-20°C can range from 20 to 2000 respectively, for liquid flow rates ranging from 1 ml/min to 100 ml/min respectively.
  • the shape of the channel segment 435 is not limited to the more or less rectangular shape with rounded corners depicted in FIG. 4 (and respective cross-section in FIG. 5); other shapes for the segment 435 are also contemplated by the instant invention to be used by a person of ordinary skill in the art, yet still fall within the scope of the present invention.
  • alternate shapes are also contemplated for the restriction 460 besides dimple-like.
  • the cross-section shown in FIG. 5 will vary depending of course on the different shapes of the mixer elements of FIG. 4.
  • the number of mixer elements placed in series can range anywhere from one to whatever minimum number of elements produces the desired mixing efficiency. In many instances, the addition of more mixer elements will not necessarily increase the mixing efficiency.
  • the dimensions of each of the mixer elements can also have a varying range, depending on desired mixing efficiency in accordance with novel aspects of the present invention.
  • the combination of a continuous, localized flow path may position the pillars or cylindrical posts 450 (or other types of obstacles) in the middle of the channel segment 435 or anywhere else rather than at the ends of the channel within the chamber 440 with or without restrictions 460 and still create desirable mixing and appropriate flow or acceleration of liquids flowing through the path.
  • FIGs. 6a and 6b several preferred design structures 610 through 680 for mixer 400 are shown that fall within the scope of the present invention's mixer principles.
  • Each layer of mixer 400 is displayed by three rectangular shapes; for example, 610a and 610b signify the top and bottom layers of mixer elements, respectively, while 610c represents the final assembled structure of one single microstucture mixer produced by the top layer 610a being assembled over the bottom layer 610b in accordance with the preferred embodiment of the present invention.
  • the layers shown in FIGs. 6a and 6b are preferably made of glass, ceramic or glass-ceramic substrate materials.
  • Each mixer design is preferably formed on a wafer.
  • This top, bottom and assembled 3-layer scheme is representative of all the mixers shown in FIGs. 6a and 6b, except for mixer 680 where only top and bottom layers, at 675 and 680 respectively, are shown.
  • fabrication occurs by having two layers come together to form a third assembled layer.
  • the structures depict the mixer elements structured in series.
  • Putting two series of mixer elements in parallel may not be as desirable due to the potential deviation of the ratio between the flow rates of the fluids or reactants (from its value at the inlet) in each branch 662a and 662b.
  • the mixing efficiency is adequate in each branch 662a and 662b, but the stoechiometry cannot be conserved.
  • this type of flow separation is a useful way to reduce the overall pressure drop.
  • FIGs. 6a and 6b Many structural mixer design details are shown in the preferred mixer embodiments in FIGs. 6a and 6b to include variations in the number and size of mixer elements, the injection zone design and the restriction in the segments. Increasing the number of mixer elements will increase the pressure drop created by the mixer as is shown in plots of FIGs. 9-11 infra. This is shown to also increase the mixing completeness (or efficiency).
  • mixer 680 the regions 685 and 690 at top and bottom layers 675 and 676 indicate the injector zone regions in accordance with a preferred embodiment of the present invention. These injection zones 685 and 690 have been modified to enhance mixing by creating two interfaces coming from the injector 685 and 690.
  • the interfaces between the fluids are created by core fluids in the cores 677 and 678 when assembly of 675 and 676 takes place. These fluids are controlled at first interaction in accordance with a preferred embodiment of the present invention._Though in this embodiment, there are two interface with two fluids, depending on how many additional fluids, the number of interfaces between the fluids may increase.
  • the injection zone, including interfaces and single or multiple cores, is further described infra with respect to FIGs. 8 and 8a.
  • FIGs. 7a and 7b the corresponding preferred dimensions of the mixer elements used for fabrication of embodiments depicted in FIGs. 6a and 6b are shown in accordance with a preferred aspect of the present invention,
  • the data for dimensions such as radius, length, etc. of mixer elements 611, 646, 656 or 666 of FIGs. 6a and 6b are diagrammed, and so forth.
  • the preferred dimensions of injection zone 661 of embodiment 660 of FIG. 6b are detailed.
  • the preferred dimensions of mixer elements 616 or 657 of FIGs. 6a and 6b are delineated; at 740 the preferred dimensions of mixer element 621 of FIG. 6a are set down; at 750 the preferred dimensions of mixer element 626 of FIG.
  • a typical testing process would be to prepare, at room temperature, a solution of acid chloride and a solution of potassium acetate mixed with KI (Potassium Iodide). Both these fluids or reactants would be continuously injected by means of a syringe pump into a mixer or reactor (i.e. the one to be tested in terms of mixing). There would be a continuous fluid flowing out from the mixer through a flow thru cell or cuvette (lO ⁇ liters) where quantification is made by transmission measurement at 350nm. Any extraneous fluids would be collected as waste.
  • the quality of mixing for the present invention is ideal for a 100% value.
  • Pressure drop data is acquired using water at 22°C and peristaltic pumps.
  • the total flow rate is measured at the outlet of the mixer or reactor 430 as shown in FIG. 4 using a pressure transducer by measuring the upstream absolute pressure value, where the outlet of the mixer 430 (or mixer embedded in a micro reactor system as shown infra) is open to atmospheric pressure.
  • FIG.8 shows a group of mixers with radii ranging from 700 ⁇ m to 1300 ⁇ m in accordance with an alternative preferred embodiment of the present invention.
  • the mixers described in FIGs. 6a and 6b and FIGs. 7a and 7b supra depicted designs with dimensions such that resulting pressure drop is reasonable and mixing efficiency is appropriate
  • FIG. 8 depicts designs where there is an increase in dimensions, in particular the radius of the obstacle, to show an increase in mixing efficiency and an increase in pressure drop.
  • core element 822a acts as a control of the contacting regions where fluids interact for the first time.
  • Mixers 822, 823, 824, 826, 827, and 828 also have cores (not labeled) but the remaining mixers in FIG.
  • a multiple core injection zone design 800 is shown having two cores, 801 and 802 in an alternative preferred embodiment of the present invention. Fluids flow from right to left, as shown by directional arrows in FIG. 8a. Core fluid 804 flows from right to left within core 801 towards and through interface zone 807. Core fluid 805 flows right to left within the boundary of core 801 and core 802 towards and through interface zone 808. Core fluid 806 flows right to left within annular fluid region 803 and core 802 towards interface zone 809.
  • the core fluids 801, 802, and 803 are kept separated until they reach the entrance zone 822b of the mixer 822 (shown in FIG. 8).
  • the distance from the entrance zone 822b and the first mixer element 800 in the path will typically be 1950 ⁇ m as shown in the single core injection zone design of FIG. 8.
  • the embodiments shown in FIGs. 8 and 8a effectively control the core fluids by preventing contact between them until they are extremely close to the mixer, where the fluids then interface, enter and mix.
  • FIG. 9 shows a graph of the comparison of different designs of FIG. 8 clearly depicting the pressure drop vs. mixing efficiency relationship in accordance with an alternate embodiment of the present invention. It can be seen that increasing the pressure drop of the various mixer design structures of FIG. 8 shows a corresponding increase in mixing efficiency.
  • FIG. 10 a plot illustrates the increase in mixing quality (upwards of 90%) for a mixer with an obstacle radius of 1200 ⁇ m (as in mixer 827 of FIG. 8) - I300 ⁇ m (as in mixer 828 of FIG. 8). Additionally, FIG. ll's plot shows the relative increase in pressure drop as the radius of the obstacle is increased.
  • FIG. 12 depicts a three-dimensional split view of the mixer 400 of
  • FIG. 4 in a reactor structure 1200.
  • inlets 1210 are shown where fluids are initially introduced to reactor structure 1200 and flow through to a contacting zone 1220.
  • the top and bottom areas 1230 and 1235 of the mixer 400 are also depicted.
  • a dwell time zone or area 1240 is shown that allows the fluid a certain residence time in the micro channels based on the desired flow rate before it flows out of outlet 1250.
  • mixer design 1200 layers may be combined with heat exchange layers (not shown) within a micro reactor to provide appropriate thermal conditions of the reactant fluids in accordance with a still further aspect of the preferred embodiment of the present invention.
  • FIG. 13 a block diagram of a mixer device 1310 is shown situated within a micro reactor system 1300 in accordance with the present invention.
  • the mixer 1310 and dwell time zone 1320 represent structure 1200, described supra in FIG. 12.
  • Mixer 1310 has a source of reactants, 1311 and 1312 and two pumps 1313 and 1314.
  • Dwell time zone 1320 is a micro fluidic device that typically has a single passage that allows the fluid a certain residence time in the micro channels based on the desired flow rate.
  • a filter 1330 positioned at the output of the dwell time module 1320 can produce products 1340 and by products 1350.
  • Hydrocarbon gas or vapor
  • Hydrocarbons gas or vapor
  • oxidation reactions propylene to generate acroleine, butane to generate maleic anhydride
  • Hydrocarbons gas or vapor
  • halogenated compounds can be reacted and generate halogenated hydrocarbons (benzene with chlorine).
  • Aldehydes/ketones in water can be mixed with sodium hydroxide aqueous solution in order to be reacted and generate aldol condensation products (propionaldehyde, acetaldehyde, acetone).
  • Phenol in water can be mixed with nitric acid aqueous solution in order to be reacted and generate nitration products.
  • Liquid hydrocarbons can be mixed with mixtures of sulfuric acid and nitric acid in order to be reacted and generate nitration products (toluene, naphthalene, etc.).
  • Hydrogen peroxide can be mixed with liquid hydrocarbons to generate selective oxidation products (phenol oxidation to hydroquinone, catechol)
  • Gas can be mixed with liquids in order to be dissolved and then trapped (SO2 in sodium hydroxide aqueous solutions) or reacted (SO3 in sulfuric acid to generate oleum and then operate sulfonation reactions).
  • Ozone air, oxygen
  • hydrocarbon solutions to then operate selective oxidation reactions whether they are homogeneous catalytic reactions (cyclohexane or paraxylene oxidations) or heterogeneous catalytic reactions (phenol, cumene).
  • this latter solution can be used when a reaction has one or more of the products which is a solid being mixed and reacted with amine and acylchloride hydrocarbons in the presence of a tertiary amine solvent. This yields corresponding amides and quaternary ammonium salt which is insoluble in the mixture.

Abstract

A class of designs is provided for a mixer in micro reactors where the design principle includes at least one injection zone (410) in a continuous flow path where at least two fluids achieve initial upstream contact and an effective mixing zone (i.e. adequate flow of fluids and optimal pressure drop) containing a series of mixer elements (430) in the path. Each mixer element is preferably designed with a chamber at each end in which an obstacle (450) is placed (thereby reducing the typical inner dimension of the chamber) and with optional restrictions (460) in the channel segments. The obstacles are preferably cylindrical pillars but can have any geometry within a range of dimensions and may be in series or parallel along the flow path to provide the desired flow-rate, mixing and pressure-drop. The injection zone may have two or more interfaces and may, include one or more cores to control fluids before mixing.

Description

TITLE OF THE INVENTION
MICROSTRUCTURE DESIGNS FOR OPTIMIZING MIXING AND PRESSURE DROP
FIELD OF THE INVENTION This invention relates generally to micro reactor systems and devices and more particularly to a class of designs for mixers used within micro reactor systems.
BACKGROUND OF THE INVENTION
Many multiphase fluidic applications require mixing or at least enhancement of interfacial area. In micro-fluidic systems, typical dimensions are below 1mm and make the mixing and/or the agitation a first order issue. Indeed the typical flows often involved in these applications are creeping flows in which two initial miscible or non miscible fluids hardly mix by themselves (turbulence in fluid flows being commonly used for achieving mixing in large-scale fluid systems). Increasing the interfacial area between two fluids or mixing at very small scales without external stirring or mechanical action is very difficult because of the low Reynolds numbers involved, especially for nearly two dimensional geometries. Therefore, reaction processes are largely diffusion limited.
The concept of mixing liquids in a path is necessary to create adequate liquid flow in a micro reactor system or more particularly, in a mixer design or module within a micro reactor system. Typically, there is a source of reactants or a least a plurality of fluid connections for delivering reactants at an injection zone for upstream flow. Typically, liquids in the prior art include water, aqueous and organic liquid solutions.
Many have developed mixers of several types to generate mixing in micro systems. Whatever mixing solution is chosen, the mixer may be implemented within a complete micro system. The required attributes for the mixers are therefore extended beyond mixing efficiency, whereby mixer dimensions can preferably be changed to affect pressure drop, but not affect mixing efficiency or at least have a minimum effect on mixing efficiency.
In such micro reactor systems, it is therefore desirable to have a mixer with maximum efficiency at very low pressure drop. Furthermore, it is desirable to generate appropriate mixing within the structure of the path. Prior art approaches for performing the above described desired capabilities that are known in the art include the following examples.
For instance, a typical split and recombine solution is shown in FIG. 1 and described in US Patent Number 5,904,424 Al entitled " Device for Mixing Small Quantities of Liquids". In this patent, in order to reduce the length over which the reactants need to diffuse, the inlet reactant streams are separated and recombined in a multi-layered structure.
Further prior art implementations of this principle are disclosed by IMM. (Refer to http://imm.mediadialoa24.de/v0/wseitene/wleistunq/misch2.html). Here, the IMM mixing split-reco bine concept of caterpillar mixers includes two unmixed fluid streams divided such that two new regions are formed and are further down recombined. All four regions are ordered alternatively next to each other such that the original geometry is re-established. There are also prior art three-dimensional flows that represent chaotropic solutions. These designs solve the problem of mixing by creating a transverse flow without requiring the use of moving mixer elements. Another similar prior art chaotropic mixer can be found for instance, in International Publication Number WO03/011443A2, entitled, * Laminar Mixing Apparatus and Methods" assigned to the President and Fellows of Harvard College. Here, the helical flow is created by weak modulations of the shape of the walls of the channel, or by grooves defined on the channel wall allowing mixing of a fluid with a Reynolds number of less than 100 thereby capably mixing a fluid flowing in the micro-regime. A similar prior art structure is shown in FIG. 2.
Cellular Process Chemistry (CPC), a German company, cites a design using liquid slugs and a decompression chamber in European Patent Application EP1123734A2 entitled "Miniaturized Reaction Apparatus" published on August 16, 2001 as shown in FIG. 3.
Disadvantages of these prior art solutions will be outlined below. For- instance, with respect to the first prior art approach, split and recombine design requires significant dimensional precision for the manufacture of these designs. This is necessary to ensure that the upstream flow splits equally in each sub-channel before the recombination, so that the flowrates ratio of the liquid that are mixed is equal to the inlet ratio set by the user. The second approach utilizing three-dimensional or chaotropic flows has several drawbacks, one being the aspect ratio between the height and width of the channel, another being costly technology, and yet another being that it is useful for liquids only and not gas-liquid systems. The third prior art approach, the liquid slugs device similarly has all the drawbacks of those approaches described above. Its only advantage is that low pressure drop due to parallelization and decompression reduces dimensions efficiently.
All the above devices have great difficulty achieving low pressure drop. This is generally thought to be caused by the prior art designs' attempts at reducing dimensions to enhance mixing efficiency thereby dramatically increasing the pressure drop, which is a penalty.
A new approach is needed that preferably overcomes the disadvantages of any of the prior art solutions above that provide optimal pressure drop by tuning inner dimensions; localized liquid flow at geometric obstacles and restrictions in the path structure; mixing generated in the path structure via obstacles and by reducing local dimensions; fully three dimensional flow between obstacles; control at the initial contact region at injection; and robustness of efficiency with respect to fluids.
The term fluid is herein defined as including miscible and immiscible liquid-liquids, gas-liquids and solids. SUMMARY OF THE INVENTION
A class of designs is provided for a mixer in microreactors where the design principle includes an injection zone with one or more interfaces and cores where two or more fluids achieve initial upstream contact and an effective mixing zone containing a series of mixer elements in the flow path and wherein each mixer element is designed with a chamber at the end in which an obstacle such as a pillar is placed to reduce the typical inner dimension and an optional restriction in the channel segment. Additionally, the preferred embodiment can have many permutations in its design whereby for instance, it can also include an injection-mixing-injection concept where additional fluid-mixing is done further downstream. One embodiment of the present invention relates to a mixer apparatus having at least one injection zone of a continuous flow path where a plurality of fluids make initial contact and at least one mixer element in the flow path, the at least one mixer element efficiently mixing the fluids through the path. Each one of the mixer elements includes a channel segment, a chamber disposed at ends of the channel segment and each chamber further includes at least one obstacle.
Another embodiment of the present invention relates to at least one obstacle situated anywhere in the flow path.
Another embodiment of the present invention relates to the channel segment further including at least one restriction, the segment having a radius in the range of lOOμm to 5000μm, height in the range of lOOμm to 5000μm, a width in the range of lOOμm to lOOOOμm, and a length in the range of 200μm to lOOOOμm and the restriction having a a height in the range of lOOμm to 5000μm and a width in the range of 50μm to 2500μm.
Another embodiment of the present invention relates to inner dimensions of the chamber being reduced in the presence of the at least one obstacle and wherein increased dimensions of said obstacle increase the mixing efficiency.
Another embodiment of the present invention relates to the at least one obstacle having any geometry with a radius in the range of 50μm to 4000μm and a height of lOOμm to 5000μm and wherein the inner dimensions of the chamber in the presence of the at least one obstacle are further characterized by a radius in the range of lOOμm to 5000μm, a perimeter from 600μm to 30mm, a surface area from 3mm2 to 80mm2, a volume from 0.3mm3 to 120mm3, and a height in the range between lOOμm and 5000μm. Another embodiment of the present invention relates to the at least one injection zone having at least one core and fluids in the at least one core flow through and towards a plurality of interfaces. Another embodiment of the present invention relates to the mixer apparatus being embedded in a micro reactor system, the system including at least one of the following: a reactant fluid source, a pump, a dwell time zone and an output filter. Another aspect of the embodiment of the present invention relates to the mixer apparatus preferably made of glass, ceramic or glass-ceramic substrate materials.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the invention as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework to understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment(s) of the invention, and together with the description serve to explain the principles and operation of the invention. BRIEF DESCRIPTION OF THE DRAWINGS
The invention is further illustrated with reference to the following drawings in which:
FIG. 1 is an example of a prior art split and recombine mixer.
FIG. 2 is an example of a prior art chaotropic mixer.
FIG.3 is an example of a prior art slug and decompression mixer.
FIG. 4 is a three-dimensional schematic view of a mixer in accordance with a preferred embodiment of the present invention.
FIG. 5 is a cross-sectional view of FIG. 4 in the center of a mixer post in accordance with a preferred embodiment of the present invention.
FIGs. 6a and 6b are top views of layers of the mixer design in accordance with a preferred embodiment of the present invention.
FIGs. 7a and 7b show typical dimensions of the mixer designs of FIGs. 6a and 6b in accordance with a preferred embodiment of the present invention.
FIG. 8 is a top view of alternate mixer designs with increased dimensions in accordance with a preferred embodiment of the present invention. FIG. 8a shows a multiple core injection zone in accordance with an alternate preferred embodiment of the present invention. FIGs. 9-11 are plots of pressure drop and mixing quality of various mixer designs of FIG. 8 having varying dimensions in accordance with a preferred embodiment of the present invention. FIG. 12 shows a top view of a mixer embedded in a mixer reactor structure in accordance with a preferred embodiment of the present invention.
FIG. 13 shows a block diagram of the mixer of FIG. 12 in a micro reactor system in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Referring to FIG. 4, a three-dimensional view of mixer 400 is shown in accordance with a preferred embodiment of the present invention to include an injection zone 410 where two or more fluids or reactants (not shown) would make initial contact and flow upstream as indicated at arrow 420. Forming a somewhat snake-like shape, a series of mixer elements 430 are shown to include: 1.) fairly rectangular channel segments 435 (with slightly rounded corners); and 2.) a chamber 440 at each end of the channel segment, with an obstacle 450 positioned inside of the chamber in accordance with a preferred embodiment of the present invention of the mixer 400. In accordance with another aspect of the preferred embodiment of the present invention, the obstacle 450 is a cylindrical pillar or post placed within chamber 440, thereby reducing the inner dimension 442 of the chamber 440. Additionally, in an alternate preferred embodiment of the present invention, a restriction 460 that is dimple-like may be present on one or both sides of segment 435. In a still further alternative preferred embodiment, an injection-mixing-injection layout (not shown) is provided where additional fluid-mixing is accomplished further downstream.
In accordance with the preferred embodiment of the present invention, the obstacle 450 dimension ranges include: a radius or related dimension of 50μm to 4000μm and a height of lOOμm to 5000μm.
Channel segment 435 ranges include: a radius of lOOμm to 5000μm, height of lOOμm to 5000μm, a width of lOOμm to lOOOOμm, and a length of 200μm to lOOOOμm in accordance with the preferred embodiment of the present invention.
Restriction 460 dimension ranges include: a width of 50μm to 2500μm and a height of lOOμm to 5000μm in accordance with the preferred embodiment of the present invention.
The inner dimension of the chamber 442 in the presence of the obstacle 450 has a radius in the range of lOOμm to 5000μm, with a perimeter ranging from 600μm to 30mm, a surface from 3mm2 to 80mm2, and a volume from 0.3mm3 to 120mm3 (with heights between lOOμm and 5000μm) in accordance with the preferred embodiment of the present invention.
It is generally desirable to reduce this inner dimension so that the length over which the reaction occurs (for the diffusion process) is reduced. Though not shown, it is contemplated that there may be more than one obstacle 450 in each chamber 440 if desired efficiency is achieved. Furthermore, in the preferred embodiment of a series of mixer elements 430, solid particles, if present, in the fluid flow stream will aptly flow through the mixer elements. Designs using reduced dimensions after parallelization (e.g. where the reactant stream is split into one upstream channel and multiple downstream channels) typically have additional problems with solid particle flow thereby decreasing the efficiency of the mixer.
FIG. 5 shows a cross-section view of an obstacle 450, shown as a pillar in FIG. 4, in accordance with the present invention. The pillar 450 creates a tortuous patfi for the liquids or reactants to flow through, thereby creating adequate flow which may include accelerating the flow of the liquids or reactants locally, due to reduced inner dimensions. FIG. 5 depicts this tortuous flow within the cavity 512 of chamber 440 via arrows 510 and 520.
Even though the flow remains typically laminar, there is a significantly higher velocity in the restriction in and around the pillars 450 to generate mixing. For the structure in FIG. 5, the Reynolds numbers (water-20°C) can range from 20 to 2000 respectively, for liquid flow rates ranging from 1 ml/min to 100 ml/min respectively.
Mixing is generated in this preferred embodiment of the present invention for at least three apparent reasons: 1.) flow is unstable after a cylinder at Reynolds number higher than approximately 20, covering the range of flow rates of the present invention. It should be noted that while there is no precise value for such a complex geometry, the order of magnitude is between 50 & 500; 2.) the tortuous flow path allows inertia to play a role and adequately mix the fluid; and 3.) reduction of the thickness of the reactant fluid by reduction of the internal dimensions of the channels through which the fluid is circulating, which has trie effect of reducing length over which diffusion has to occur, thereby reducing characteristic time needed for diffusion.
Many other mixer element embodiments are contemplated by the present invention whose results would practically be the same and where the shape of the various mixer elements structures would be a design choice for enhancing the capability of mixing. While cylinder shaped pillars are described as being the preferred embodiment for the obstacle 450 in FIG. 4, any other geometrical shape (triangular, rhombus, diamond, etc.) within the realm of possibility, with or without grooves or other delineations on its surface, are envisioned falling within the scope of this invention. It is also contemplated that not all obstacles 450 within one mixer 400 necessarily have the same geometry. They may, for a particular mixer design, require all different shapes and sizes, be alternating and/or populate the segments in whatever manner suits the proper and desired mixing. Furthermore, the shape of the channel segment 435 is not limited to the more or less rectangular shape with rounded corners depicted in FIG. 4 (and respective cross-section in FIG. 5); other shapes for the segment 435 are also contemplated by the instant invention to be used by a person of ordinary skill in the art, yet still fall within the scope of the present invention. Similarly, alternate shapes are also contemplated for the restriction 460 besides dimple-like. As such, the cross-section shown in FIG. 5 will vary depending of course on the different shapes of the mixer elements of FIG. 4. Furthermore, the number of mixer elements placed in series can range anywhere from one to whatever minimum number of elements produces the desired mixing efficiency. In many instances, the addition of more mixer elements will not necessarily increase the mixing efficiency. Additionally, as mentioned supra, and as shown infra in FIGs. 7a and 7b for example, the dimensions of each of the mixer elements can also have a varying range, depending on desired mixing efficiency in accordance with novel aspects of the present invention.
In an alternate preferred embodiment of the present invention, the combination of a continuous, localized flow path may position the pillars or cylindrical posts 450 (or other types of obstacles) in the middle of the channel segment 435 or anywhere else rather than at the ends of the channel within the chamber 440 with or without restrictions 460 and still create desirable mixing and appropriate flow or acceleration of liquids flowing through the path. Furthermore, in yet another alternative preferred embodiment of the present invention, there is a novel control of the injection zone and the interface zone or contacting region where fluids interact for the first time. This latter control is described in some further detail infra with respect to FIGs. 6a, 6b7 and FIGs. 8 and 8a.
It should be emphasized that in all the preferred embodiments described herein, the pressure drop created by the actual mixer structure and the mixing quality can be adjusted to a desired balance by one of ordinary skill in the art to achieve optimum performance by changing the design dimensions accordingly.
Mixing typically occurs in the -y' plane, and as such, dimensional changes in the horizontal plane usually affect mixing quality. Height is a dimension in the vertical 'z' plane and typically has a first order impact on pressure drop and a second order impact on mixing quality, the latter being impacted more by the mixer elements 430 described supra. Referring now to FIGs. 6a and 6b, several preferred design structures 610 through 680 for mixer 400 are shown that fall within the scope of the present invention's mixer principles. Each layer of mixer 400 is displayed by three rectangular shapes; for example, 610a and 610b signify the top and bottom layers of mixer elements, respectively, while 610c represents the final assembled structure of one single microstucture mixer produced by the top layer 610a being assembled over the bottom layer 610b in accordance with the preferred embodiment of the present invention. The layers shown in FIGs. 6a and 6b are preferably made of glass, ceramic or glass-ceramic substrate materials. Each mixer design is preferably formed on a wafer. This top, bottom and assembled 3-layer scheme is representative of all the mixers shown in FIGs. 6a and 6b, except for mixer 680 where only top and bottom layers, at 675 and 680 respectively, are shown.
As stated above, in the preferred embodiments of the present invention, fabrication occurs by having two layers come together to form a third assembled layer. For other design embodiments, however, it is possible to have one micro-patterned layer coming together with a bare or a coated glass, ceramic, or glass-ceramic substrate.
In preferred embodiments 610, 615, 620, 625, 630, 635, 640, 645, 650, 655, 665, 670, and 672 (representing the majority of embodiments shown in FIGs. 6a and 6b), the structures depict the mixer elements structured in series. Putting two series of mixer elements in parallel (shown in FIG. 6b at 660 and 680), while also possible with the same design principle, may not be as desirable due to the potential deviation of the ratio between the flow rates of the fluids or reactants (from its value at the inlet) in each branch 662a and 662b. In this embodiment at 660, the mixing efficiency is adequate in each branch 662a and 662b, but the stoechiometry cannot be conserved. However, this type of flow separation is a useful way to reduce the overall pressure drop.
Many structural mixer design details are shown in the preferred mixer embodiments in FIGs. 6a and 6b to include variations in the number and size of mixer elements, the injection zone design and the restriction in the segments. Increasing the number of mixer elements will increase the pressure drop created by the mixer as is shown in plots of FIGs. 9-11 infra. This is shown to also increase the mixing completeness (or efficiency). Referring now to mixer 680, the regions 685 and 690 at top and bottom layers 675 and 676 indicate the injector zone regions in accordance with a preferred embodiment of the present invention. These injection zones 685 and 690 have been modified to enhance mixing by creating two interfaces coming from the injector 685 and 690. The interfaces between the fluids are created by core fluids in the cores 677 and 678 when assembly of 675 and 676 takes place. These fluids are controlled at first interaction in accordance with a preferred embodiment of the present invention._Though in this embodiment, there are two interface with two fluids, depending on how many additional fluids, the number of interfaces between the fluids may increase. The injection zone, including interfaces and single or multiple cores, is further described infra with respect to FIGs. 8 and 8a.
Referring now to FIGs. 7a and 7b, the corresponding preferred dimensions of the mixer elements used for fabrication of embodiments depicted in FIGs. 6a and 6b are shown in accordance with a preferred aspect of the present invention, For instance at 710, the data for dimensions such as radius, length, etc. of mixer elements 611, 646, 656 or 666 of FIGs. 6a and 6b are diagrammed, and so forth. At 720, the preferred dimensions of injection zone 661 of embodiment 660 of FIG. 6b are detailed. Furthermore at 730, the preferred dimensions of mixer elements 616 or 657 of FIGs. 6a and 6b are delineated; at 740 the preferred dimensions of mixer element 621 of FIG. 6a are set down; at 750 the preferred dimensions of mixer element 626 of FIG. 6a are defined; at 760 the preferred dimensions of mixer element 631 of FIG. 6a are shown; at 770 the preferred dimensions of mixer element 636 of FIG. 6a are set down; at 780 the preferred dimensions of mixer element 641 of FIG. 6a are defined; at 790 the preferred dimensions of mixer element 651 of FIG. 6a are defined; and at 792 and 794 the preferred dimensions of mixer elements 671 and 673 of FIG. 6b are defined.
A testing method used to quantify mixing quality of two miscible liquids is described in Villermaux J., et al. Use of Parallel Competing Reactions to Characterize Micro Mixing Efficiency, AIChE Symp. Ser. 88 (1991) 6, p.
286. A typical testing process would be to prepare, at room temperature, a solution of acid chloride and a solution of potassium acetate mixed with KI (Potassium Iodide). Both these fluids or reactants would be continuously injected by means of a syringe pump into a mixer or reactor (i.e. the one to be tested in terms of mixing). There would be a continuous fluid flowing out from the mixer through a flow thru cell or cuvette (lOμliters) where quantification is made by transmission measurement at 350nm. Any extraneous fluids would be collected as waste.
Using this testing method at room temperature on the structures described herein, the quality of mixing for the present invention is ideal for a 100% value. Pressure drop data is acquired using water at 22°C and peristaltic pumps. The total flow rate is measured at the outlet of the mixer or reactor 430 as shown in FIG. 4 using a pressure transducer by measuring the upstream absolute pressure value, where the outlet of the mixer 430 (or mixer embedded in a micro reactor system as shown infra) is open to atmospheric pressure.
FIG.8 shows a group of mixers with radii ranging from 700μm to 1300μm in accordance with an alternative preferred embodiment of the present invention. It should be noted that the mixers described in FIGs. 6a and 6b and FIGs. 7a and 7b supra depicted designs with dimensions such that resulting pressure drop is reasonable and mixing efficiency is appropriate, whereas FIG. 8 depicts designs where there is an increase in dimensions, in particular the radius of the obstacle, to show an increase in mixing efficiency and an increase in pressure drop. In FIG. 8, core element 822a acts as a control of the contacting regions where fluids interact for the first time. Mixers 822, 823, 824, 826, 827, and 828 also have cores (not labeled) but the remaining mixers in FIG. 8 do not illustrate this core feature. Referring to FIG. 8a, a multiple core injection zone design 800 is shown having two cores, 801 and 802 in an alternative preferred embodiment of the present invention. Fluids flow from right to left, as shown by directional arrows in FIG. 8a. Core fluid 804 flows from right to left within core 801 towards and through interface zone 807. Core fluid 805 flows right to left within the boundary of core 801 and core 802 towards and through interface zone 808. Core fluid 806 flows right to left within annular fluid region 803 and core 802 towards interface zone 809.
The core fluids 801, 802, and 803 are kept separated until they reach the entrance zone 822b of the mixer 822 (shown in FIG. 8). The distance from the entrance zone 822b and the first mixer element 800 in the path will typically be 1950μm as shown in the single core injection zone design of FIG. 8. The embodiments shown in FIGs. 8 and 8a effectively control the core fluids by preventing contact between them until they are extremely close to the mixer, where the fluids then interface, enter and mix. FIG. 9 shows a graph of the comparison of different designs of FIG. 8 clearly depicting the pressure drop vs. mixing efficiency relationship in accordance with an alternate embodiment of the present invention. It can be seen that increasing the pressure drop of the various mixer design structures of FIG. 8 shows a corresponding increase in mixing efficiency. Similarly, in FIG. 10, a plot illustrates the increase in mixing quality (upwards of 90%) for a mixer with an obstacle radius of 1200μm (as in mixer 827 of FIG. 8) - I300μm (as in mixer 828 of FIG. 8). Additionally, FIG. ll's plot shows the relative increase in pressure drop as the radius of the obstacle is increased. FIG. 12 depicts a three-dimensional split view of the mixer 400 of
FIG. 4 in a reactor structure 1200. In accordance with the present invention, inlets 1210 are shown where fluids are initially introduced to reactor structure 1200 and flow through to a contacting zone 1220. The top and bottom areas 1230 and 1235 of the mixer 400 are also depicted. A dwell time zone or area 1240 is shown that allows the fluid a certain residence time in the micro channels based on the desired flow rate before it flows out of outlet 1250. It is contemplated that mixer design 1200 layers may be combined with heat exchange layers (not shown) within a micro reactor to provide appropriate thermal conditions of the reactant fluids in accordance with a still further aspect of the preferred embodiment of the present invention.
Referring now to FIG. 13, a block diagram of a mixer device 1310 is shown situated within a micro reactor system 1300 in accordance with the present invention. The mixer 1310 and dwell time zone 1320 represent structure 1200, described supra in FIG. 12. Mixer 1310 has a source of reactants, 1311 and 1312 and two pumps 1313 and 1314. Dwell time zone 1320 is a micro fluidic device that typically has a single passage that allows the fluid a certain residence time in the micro channels based on the desired flow rate. A filter 1330 positioned at the output of the dwell time module 1320 can produce products 1340 and by products 1350.
It should be noted that all figures described supra are not of actual size but represent accurate renditions and structural block diagrams of the preferred embodiments of the present invention. Several commercial applications are contemplated for use with the embodiments of the present invention such as, but not limited to, for instance, applications involving mixing both aqueous and organic liquids where these liquids are miscible and immiscible and applications mixing a reactive gas with a liquid, substituting one liquid reactant by inert or reactive gas. Furthermore, liquids can be constituted of a solid that has been dissolved in appropriate solvent, or dispersed in a liquid as mentioned supra. Some non-limiting examples of such liquids include:
1.) Homogeneous gas phase reactions: Hydrocarbon (gas or vapor) can be mixed with air in order to then be reacted in a catalytic zone for selective oxidation reactions (propylene to generate acroleine, butane to generate maleic anhydride). Hydrocarbons (gas or vapor) can be mixed with halogenated compounds to be reacted and generate halogenated hydrocarbons (benzene with chlorine).
2.) Homogeneous liquid phase reactions: Aldehydes/ketones in water can be mixed with sodium hydroxide aqueous solution in order to be reacted and generate aldol condensation products (propionaldehyde, acetaldehyde, acetone). Phenol in water can be mixed with nitric acid aqueous solution in order to be reacted and generate nitration products.
3.) Heterogeneous liquid phase reactions: Liquid hydrocarbons can be mixed with mixtures of sulfuric acid and nitric acid in order to be reacted and generate nitration products (toluene, naphthalene, etc....). Hydrogen peroxide can be mixed with liquid hydrocarbons to generate selective oxidation products (phenol oxidation to hydroquinone, catechol)
4.) Heterogeneous gas/liquid reactions: Gas can be mixed with liquids in order to be dissolved and then trapped (SO2 in sodium hydroxide aqueous solutions) or reacted (SO3 in sulfuric acid to generate oleum and then operate sulfonation reactions). Ozone (air, oxygen) in hydrocarbon solutions to then operate selective oxidation reactions whether they are homogeneous catalytic reactions (cyclohexane or paraxylene oxidations) or heterogeneous catalytic reactions (phenol, cumene).
Additionally, this latter solution can be used when a reaction has one or more of the products which is a solid being mixed and reacted with amine and acylchloride hydrocarbons in the presence of a tertiary amine solvent. This yields corresponding amides and quaternary ammonium salt which is insoluble in the mixture. Having described various preferred embodiments of the present invention, it will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A mixer apparatus, said apparatus characterized by: at least one injection zone of a continuous flow path where a plurality of fluids make initial contact; and at least one mixer element in said flow path, said at least one mixer element efficiently mixing said plurality of fluids through said path.
2. The mixer apparatus of Claim 1 wherein each of said at least one mixer elements is further characterized by a channel segment, a chamber disposed at ends of said channel segment wherein each chamber further includes at least one obstacle.
3. The mixer apparatus of Claim 1 wherein at least one obstacle is situated anywhere in said flow path.
4. The mixer apparatus of Claim 2 or 3 wherein said channel segment is further characterized by at least one restriction, said segment having a radius in the range of lOOμm to 5000μm, height in the range of lOOμm to 5000μm, a width in the range of lOOμm to lOOOOμm, and a length in the range of 200μm to lOOOOμm and said restriction having a radius in the range of 50μm to 2500μm and a height in the range of lOOμm to 5000 μ .
5. The mixer apparatus of any one of Claims 2 to 4 wherein inner dimensions of said chamber is reduced in the presence of said at least one obstacle and wherein increased dimensions of said obstacle increase said mixing efficiency.
6. The mixer apparatus of Claim 5 wherein said at least one obstacle is further characterised by having any geometry with a radius in the range of 50μm to 4000μm and a height of lOOμm to 5000μm; and wherein said inner dimensions of said chamber in the presence of said at least one obstacle are further characterised by a radius in the range of lOOμm to 5000μm, a perimeter from 600μm to 30mm, a surface area from 3mm to 80mm , a volume from 0.3mm to 120mm , and a height in the range between lOOμm and 5000μm.
7. The mixer apparatus according to any one of Claims 1 to 6 wherein said at least one injection zone further comprises at least one core.
8. The mixer apparatus according to any one of Claims 1 to 7 wherein said at least one injection zone controls said fluids in said at least one core flowing through and towards a plurality of interfaces.
9. The mixer apparatus of any of Claims 1 to 8, wherein said mixer apparatus is combined with a micro reactor system, said system further characterized by at least one of the following: a reactant fluid source, a pump, a dwell time zone and an output filter.
10. The mixer apparatus of any of Claims 1 to 9 made of glass, ceramic or glass-ceramic substrate materials.
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