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
  • 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
  • B01F25/4332—Mixers with a strong change of direction in the conduit for homogenizing the flow
• • 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
  • B01F25/4331—Mixers with bended, curved, coiled, wounded mixing tubes or comprising elements for bending the flow

Definitions

• the subject matter of the present invention in general, pertains to enhanced radial mixing of fluids, and more particularly to Compact Coiled Flow Inverters (CCFIs) to be used as in-line mixers.
• CCFIs Compact Coiled Flow Inverters
• Mixing is an important operation in process industries. Therefore, various mixers are used for a range of applications such as blending, mixing of viscous fluids, heat transfer, mass transfer and chemical reactions.
• the level of mixing has a direct role in conversion in a chemical reaction and selectivity of desired products, and thus always plays an important role to affect the product quality. For reactions, sometimes it is good, sometimes it is bad. What is required is "controlled mixing”. It is almost always desired to have good radial mixing and controlled axial mixing (or back-mixing) to obtain good reactor performance.
• the conventional mode of mixing offers good mixing, but ai high shear and mixes the fluid elements of different ages which result in nonuniform transient concentration. Mixing is such conduits is desirable, but the high shear is not. It is required to have sufficient radial mixing within conduits that provide an almost similar mean residence time for all fluid elements (as against an undesirable situation in which different fluid elements have different times of residence, whether predictably different or randomly different).
• the commonly used techniques to enhance radial mixing within conduits involves the generation of turbulent eddies by using in-line static mixing, structures that provide better mixing performance at low operational cost due to no moving parts. In either of these two cases, high shear is encountered, which may de-nature (lie chemicals that are being mixed. Sometimes, high shear rates lead to over-heating, and the high temperature may also de-nature of chemically change the species being mixed.
• a static mixer is a precision engineered device for the continuous mixing of fluid materials. Normally the fluids to be mixed are liquid, but static mixers can also be used to mix gas streams, disperse gas into liquid or blend immiscible liquids. The energy needed for mixing comes from a loss in pressure as fluids flow through the static mixer.
• One design of static mixer is the plate-type mixer and another common device type consists of mixer elements contained in a cylindrical (tube) or square housing. Typical construction materials for static mixer components included stainless steel, polypropylene. Teflon, PVDF, PVC, CPVC and polyacetal.
• the in-line static mixers use the energy of flowing fluid to cause the radial mixing by redistributing the fluid in across wise direction with respect to the main flow stream.
• very heat-sensitive fluid streams such pharmaceutical products, polymers melts and food materials
• the high shear produced by mixing structures may lead to significant viscous dissipation of mechanical energy to heat, which can cause thermal degradation of these high-value chemicals. Therefore, an ideal objective would be to achieve progressive and good radial mixing, even when the shear rate is low. i.e., in the laminar flow regime.
• the commonly used in-line static mixers are composed of axial ly placed multiple mixing structures that use the energy from pressure gradient of the flowing stream to mix.
• the choice of such a mixer is made on the basis of their superiority in operation In comparison to conventional agitator tanks. Their compact cross-section and high surface to volume ratio makes them more favourable as a mixing system.
• Various authors have reported these advantages by changing the channel/mixing dimensions/structure to brought streams of different concentrations to mix ⁇ for example, U.S. Pat No. 7484881 B2; U.S. Pat. No. 8696193 B2; U.S. Pat. No. 20140133268 A1; U.S. Pat. No. 20120106290 A1).
• the fixtures i.e.
• a heat exchanger for transferring heat from one fluid to another fluid comprises of a plurality of metallic tube continuously formed into four discrete helically wound coils, each coil having at least four turns, the coils being spatially placed such that axis of all the four helical coils of each bank are substantially in one common plane, the axis of each helical coil is at an angle of 90° to the adjacent helical coil, wherein number of banks is from 2 to 10 and ratio of diameter of the helical coil to the diameter of the tube is at least 10:1.
• the device for continuous virus inactivadon in a product flow comprises a pipe or hose having an inlet and having an outlet each connected to a product-flow line for directing the product flow, wherein the pipe or the hose is curved and/or is helically wound with a number of n windings about a winding axis (h) and has one or more direction changes and/or kinks of the winding axis (h) having an angle (a) of 45° to 180° for changing the effective direction of the normal of the centrifugal force, and wherein the device is characterized by a Dean number > 0 and a torsion parameter > 0.
• the conventional design consists of four discrete helical arms on a common plane that are joined together in a manner that each arm is at an angle of 90° with respect to its former/successive helical arm.
• This arrangement of four equidistant helical arms commonly known as one bank of Coiled Flow Inverter (CFI)
• CFI Coiled Flow Inverter
• This arrangement of helical arms results into a square duct-like structure with coiled tube wound at the boundaries and an empty interior area.
• CCFIs Compact Coiled Flow Inverters
• RSP-CCFI Rectangular Spiral Pattern-Compact Coiled Flow Inverter
• CHP-CCF1 Crosshatch Pattem- Coinpact Coiled Flow Inverter
• An object of the present invention is to facilitate the use of compact coiled flow inverters as in-line mixers.
• Another object of the present invention is to carry out in-line mixing by using the combined action of centrifugal force and multiple flow inversions.
• Another object of the present invention is to enhance further the cross- sectional mixing on a volumetric basis by utilizing the unoccupied central core of one bank CFI.
• Another object of the present invention is to have two compact structures within one bank area of the CFI to significantly enhance the mixing performance in comparison to standard CFI.
• Another object of the present invention is employing six and fifteen flow inversions to rotate periodically the axis of the Dean cells by 90° allowing significant enhancement in transverse mixing at low shear.
• Another object of the present invention is to obtaining a uniform concentration in the cross-sectional plug even in the laminar flow regime.
• Yet another object of the present invention is to provide a Rectangular Spiral Pattern-Compact Coiled Flow Inverter (RSP-CCFI).
• Yet another object of the present invention is to provide a Crosshatch Pattern -Compact Coiled Flow Inverter (CHP-CCPI).
• compact coiled flow inverters are used to carry out in-line mixing by using the combined action of centrifugal force and multiple flow inversions is disclosed.
• liquid flow occurs through a coiled tube, it experiences the action of centrifugal force, which causes the generation of two contra-rotating Dean cells, which in turn enhances cross-secrional mixing, without adversely affecting the axial mixing.
• two compact structures within one bank area of the CFI, two compact structures have been designed to significantly enhance the mixing performance in comparison to standard CFI by employing six and fifteen flow inversions to rotate periodically the Dean cells by 90° thereby allowing significant enhancement in transverse mixing at low shear and obtaining a uniform concentration in the cross-sectional plug even in the laminar flow regime.
• a Rectangular Spiral Pattern-Compact Coiled Flow Inverter (RSP-CCFI) which employs six flow inversions to rotate periodically the Dean cells by 90°, thereby allowing significant enhancement in transverse mixing at low shear.
• a Crosshatch Pattern -Compact Colled Flow Inverter (CHP-CCFI) Is disclosed which employs fifteen flow inversions to rotate periodically the Dean cells by 90° thereby allowing significant enhancement in transverse mixing at low shear
• CCP-CCFI Crosshatch Pattern -Compact Colled Flow Inverter
• FIG. 1A illustrates schematic of the Coiled Flow Inverter (CFI) as disclosed in prior an.
• Figure IB illustrates schematic of the Rectangular Spiral Pattern-Compact Coiled Flow Inverter (RSP-CCFI) within the square frame of the CFI ⁇ Ax A) according to one implementation of the present invention.
• Figure 1C illustrates schematic of the Crosshatch Pattern- Compact Coiled Flow Inverter (CHP-CCFI) within the square frame of the CFI ( A x A ) according to one implementation of the present invention.
• CHP-CCFI Crosshatch Pattern- Compact Coiled Flow Inverter
• Figure ID illustrates schematic of the Rectangular Spiral geometry within the rectangular frame ⁇ A xB) according to one implementation of the present invention.
• Figure 2 illustrates schematic for mixing process by using three different coiled geometries (CF1. RSP-CCFI, and CHP-CCFI) within, confined footprint (A xA) according to one implementation of the present invention.
• Figure 3 illustrates generalized design model of CHP-CCFI according to one implementation of the present invention.
• Figure 4A illustrates designs of (he cubical blocks to join different helical arms of CHP-CCFI according to one implementation of the present invention.
• Figure 4B illustrates designs of the triangular blocks to join different helical arms of CHP-CCFI according to one implementation of the present invention.
• Figure 5 illustrates typical step response curve for standard CF1, RSP-CCFI and CHP-CCFI at Reynolds number according to one implementation of the present invention.
• Figure 6 illustrates radial mixing behavior of fluid (in terms of Peclet number through CFI, RSP-CCFI and CHP-CCFI according to one implementation of the present invention.
• Figure 7 illustrates comparison of Peclet number per unit space occupied ((MvVfloor area) by CFI, RSP-CCFI and CHP-CCFI according to one implementation of die present invention.
• Figure 8 illustrates coefficient of mixedness for different coiled geometries (CFI, RSP-CCFI and CHP-CCFI) over variable according to one implementation of the present invention.
• the subject invention lies in Compact Coiled Flow inverters (CCFIs) being used as in-line mixers.
• CCFIs Compact Coiled Flow inverters
• Most industries today are governed by process economics and constraint on the availability of space. Thus, it is desirable to develop a design that provides not only efficacy of mixing but miniaturization too. Therefore, the proposed CCFIs have been developed to intensify the mixing efficiency of standard CFI within the single "frame”.
• the Rectangular Spiral Pattern-Compact Coiled Flow Inverter (RSP-CCFI) and Crosshatch Pattern -Compact Coiled Plow Inverter (CHP-CCFI) are made by analysing the parameters that affect the performance of the conventional CFT, that includes:
• compact coiled flow inverters carry out in-line mixing by using the combined action of centrifugal force and multiple flow inversions.
• the cross-sectional mixing in a single bank of the coiled tube is enhanced by the use of flow inversions which causes the rotation of Dean cells, which is further enhanced by cross-sectional mixing on a volumetric basis by utilizing the unoccupied central core of the CFI bank.
• compact coiled flow inverters as in-line mixer is provided for.
• cross-sectional mixing on a volumetric basis is enhanced by utilizing the unoccupied central core of one bank CFI is provided for.
• two compact structures within one bank area of the CFI is provided for that significantly enhances the mixing performance.
• a Rectangular Spiral Pattern-Compact Coiled Flow Inverter employing six flow inversions to rotate periodically the Dean cells by 90°, thereby allowing significant enhancement in transverse mixing at low shear is provided for.
• a Crosshatch Pattern -Compact Coiled Flow Inverter employing fifteen flow inversions to rotate periodically the Dean cells by 90° thereby allowing significant enhancement in transverse mixing at low shear is provided for.
• the number of inversions per bank is variable as it dependents upon the outer enclosure area of the one bank is provided for.
• the proposed CCFTs exhibits very high radial mixing performance at low shear by restructuring the design of standard colled flow inverter (CFT) whose potential applications as micro-reactor for various applications including polymerization, in-line mixer, heat exchanger, microfluidic device for process intensification, microfluidic device for nanofluid processing, milli/micro-structured heat exchanger, microfracture device for nanofluid processing, membrane module for enhanced mass transfer, liquid-liquid extractor, two-phase flow application, potential device for food processing, reactor for continuous protein refolding, reactor for continuous precipitation of clarified cell culture supernatant, suitable reactor for continuous flow chemical processes, reactor for continuous biopharmaceutical processing, reactor for continuous viral inactivation and continuous operated modular reactor design for the multiphase reaction system are well documented.
• CFT colled flow inverter
• the RSP-CCFI and CHP-CCFI provide improved mixing in all the above applications in which CF1 have been demonstrated or reported to work. This is achieved by improving the radial mixing by strategically designing the flow inversions within the same floor area.
• the present invention utilizes the unoccupied central core of the standard design of CFI to get enhanced mixing performance within the same floor area occupancy.
• the strategy of ''filling" the coil volume within the specified dimension of the CFI frame ( Ax A), referring to Figures 1 A-1C, are based on two concepts, viz., (1) amassing as maximum as possible mixing volume without altering the footprint of the CFI, so to get enhanced mixing per unit occupied floor area; and
• FIG. 1 A illustrates a conventional coiled flow inverter (CF1) while Figure IB and 1C illustrate the Rectangular Spiral Pattern-Compact Coiled Flow Inverter (RSP-CCPI) within the square frame of the CFI ( A x A ) and Crosshatch Pattern-Compact Coiled Plow Inverter (CHP-CCFI) within the square frame of the CFI (Ax A), respectively.
• RSP-CCPI Rectangular Spiral Pattern-Compact Coiled Flow Inverter
• CHP-CCFI Crosshatch Pattern-Compact Coiled Plow Inverter
• Three coiled structures have identical dimensions such as coiled tube inner diameter curvature diameter curvature ratio ( ⁇ ) and frame area (Ax A).
• the RSP-CCF1 is meant to include ail tube bank arrangements within a three- dimensional flat, cuboidal structure, as illustrated in Figure ID.
• the two innovative designs viz. RSP-CGFI and CHP-CCFI, are accommodated within the square frame (A x- A) of standard CFI.
• Figure 2 illustrates the mixing process by using the three different coiled structures of Figures 1 A-IC, where all three geometries are accommodated within the same floor area described by Ax A.
• POT the purpose of demonstrating the design procedure, a CFI of specified dimensions was fabricated as standard, that uses die optimal values of all parameters that would provide the best performance of CFI, that includes:
• Figure 1A illustrates the standard CFI of 64 coil turns on a 6 cm cylindrical base using 1 cm ⁇ inner diameter, PVC tubing with 0.3 cm wall thickness, wherein a curvature ratio of 7.6 was maintained throughout the design.
• the four discrete helical arms (shown by 1, 2, 3 and 4) were arranged at an angle of 90* with respect to their successive/former helical arm to obtain three equidistant 90° ilow inversions at point 5, 6 and 7 within a square of 42.4 cm x42.4 cm.
• Figure IB illustrates the proposed Rectangular Spiral Pattern- Compact Coiled Flow Inverter (RSP-CCF1) that amasses the maximum possible mixing volume without altering the footprint of the CFI, to enhance the mixing per unit occupied floor area based on current dimensions of standard CFI (A* A).
• the square frame of RSP-CCFI as illustrated in Figure IB, can be considered as a special case of the more general rectangular spiral geometry within a rectangular frame, as illustrated in Figure 1 D, where six 90° bends (shown as 8-13) join the seven discrete helical arms (marked as 14, 15. 16, 17, 18, 19 and 20) to accommodate as maximum as possible 90° inversions. In this case, the decision on the number of coil turns and number of 90° bends was made on the basis of occupied floor area(j4x J4).
• Each helical arm is labeled as q.
• coiling is performed in traditional CFT fashion where equal length dimension of helically coiled arm, is formed for standard CFI) so as to cover available outer dimensions (Ax A).
• Fot q > 3 coiling was stopped when a distance equal to the outer diameter of coil was left between
• Figure IB is outlined, where after coiling on first three successive helical arms (indicated as 14, IS and 16), the coiling on fourth helical arm (indicated as 17) is continued until a distance after which distance equal to outer diameter of helical arm is left
• variable non-equidistant 90° inversions can be obtained to form RSP-CCFI. It is of importance that in the RSP-CCFI of Figure 1 B, there is an increase of 23% (approx.) of mixing volume in contrast to standard CFI, owing to increased number of helical arms, and this is achieved within the same floor area. The percentage increase in the volume per unit space may vary depending upon the dimensions of CFI. Nonetheless the design procedure will remain same irrespective of the dimensions of the standard CFI as well as the type of frame (square/rectangular).
• Figure IC that illustrates the CHP-CCFI is based on the generalized design model as illustrated in Figure 3, where the entire occupied floor area (Ax A) is divided into various sub-squares, indicated by 1, 2, 3....so on, in Figure 3.
• the sides of each sub- square(s) represent the axis for coiling.
• the projected view of one such sub-square is also indicated in Figure 3.
• coiling can be started from any edge of any sub-square and can be continued in any direction.
• the starting edge of coiling is shown, in Figure 3 along with the manner in which coiling is to be continued from the starting edge for a first round of coiling, indicated by the direction of arrows.
• coiling is shifted to the immediate inner edge for the second round, as indicated in Figure 3 and continued in a similar manner.
• equations 1-2 the possible number of sub-squares along the diagonal (m) and their dimension (s xs ) are calculated by using equations 1-2.
• the value of m thus obtained by using equation 1 is round-off up to zero decimal place to report an integer for m.
• the dimension of floor area (A) is recalculated by using equation I ; which is then used in the subsequent calculations of number of 90' bends (n) by using equations 3 and 4:
• r represents the total number of sub-squares of area that can be fitted in door area (A x A) without leaving any unoccupied space in area (Ax A) .
• pitch m came out to be 3 (in round Figure) and number of 90o bends (n) came out to be 15 by using equations I to 4. Consequently, sixteen different helical arms, represented by numbers 21-36 in Figure 1C are arranged within the similar outer "/-erne" that offer fifteen equidistant 90o flow inversions, that are shown as 37 to 51 in Figure 1C.
• coiling it was not possible to have exactly same helical turns per arm rather some arms contains number of helical turns, some contain
• Figure 1C also illustrates the placement of specially designed cubical, indicated as 52-55 and triangular, indicated as 56-63 blocks amid different helical arms of the CCFT. This is because of the high-density packed structure of CCFI that makes coi ling a challenging task. Therefore, by using specially designed blocks, it is possible to attach the successive arm after the completion of coiling on the former arm. The positioning of the cubical and triangular blocks is decided on the basis of accompanying helical arms. Consequently, the triangular blocks were used to attach the two helical arms at the outer edges of the structure; while the cubical blocks were used to attach four helical arms in the central area.
• Figures 4A and 4B illustrate the cubical and triangular blocks with extended cylindrical provisions at 64 to position hollow cylindrical base for coiling.
• cubical blocks were fabricated by using 10 cm x 10cmx 10 cm cuboid, from which a central cube of 6 cm x 6 cm x 6 cm was formed, as indicated by 55 m Figure 4A with four cylindrical extensions of 5.4 cm diameter and 2 cm height as indicated by 64 in Figure 4A.
• the fabrication of triangular blocks was achieved by cutting them diagonally, as illustrated in Figure 4B.
• the triangular blocks not only join the two helical arms at the outer edge but also retain the squared shape for the CHP-CCFI so as to fit it within the frame of standard CFI.
• CHP-CCFI offers maximum closeness to plug flow condition. This is stated on the basis of dimensionless time corresponding to the first appearance of F value on threshold line (defined at slightly above zero value) at Reynolds number The definition of threshold line has been made to avoid the violation of ADM solution that postulates the zero start time of all concentration measurements.
• the dimensionless time for first appearance of F value on threshold line by CFI, RSP- CCFI and CHP-CCFI is 0.70, 0.73 and 0.80, respectively, while for ideal plug flow conditions this value is 1.0. Therefore, CHP-CCFI is suitable as mixers that express significantly enhanced radial mixing in the laminar flow regime, compared to CFI designs, by utilizing an identical floor area.
• FIG 8 illustrates the comparison between three coiled geometries on this basis, which indicates that CHP-CCFI gives prime performance over RSP-CCFI and CFI. It is noteworthy that CHP-CCFI and RSP-CCFI provide nearly 39%-83% higher and 10%- 19% lower value of the coefficient of mixedness in contrast to standard CFI, respectively. The reason for such an observation is explained by examining the Peclet number and pressure drop data prudently, which provide highest value of Peclet number and friction factor for CHP-CCFI; and higher value of Peclet number and friction factor for RSP-CCFI with respect to standard CFT.
• (he proposed compact coiled flow inverters to be used as in-line mixers offers improved performance for the applications such as microrcactor for various applications including polymerization, heat exchanger, microfluidic device for process intensification, microfluidic device for nanofluid processing, milli/microstructured heat exchanger, microstructure device for nanofluid processing, membrane module for enhanced mass transfer, liquid-liquid extractor, two-phase flow application, potential device for food processing, reactor for continuous protein refolding, reactor for continuous precipitation of clarified cell culture supernatant, suitable reactor for continuous flow chemical processes, reactor for continuous biopharmaceulical processing, reactor for continuous viral inactivation and continuous operated modular reactor design for the multiphase reaction system.
• microrcactor for various applications including polymerization, heat exchanger, microfluidic device for process intensification, microfluidic device for nanofluid processing, milli/microstructured heat exchanger, microstructure device for nanofluid processing, membrane module for enhanced mass transfer, liquid-liquid extractor, two-phase flow application, potential device
• compact, high efficiency and high-performance inline mixers using compact coiled flow inverters have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices/apparatus described. Rather, the specific features are disclosed as examples of implementations of compact coiled flow inverters carrying out in-line mixing by using the combined action of centrifugal force and multiple flow inversions.

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• 2017
  • 2017-12-15 WO PCT/IB2017/057982 patent/WO2018138566A1/en unknown
  • 2017-12-15 EP EP17894418.7A patent/EP3574276A4/de active Pending

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