FIELD OF THE INVENTION
[0001] The invention relates to apparatus comprising static mixers for passive
mixing of multiphase flow and more particularly to the intensification of the
mixing of multiphasic fluid systems such as liquid-liquid, liquid-liquid-gas
systems, and also immiscible fluids by way of cumulative twisting of the flow, in
the conduit, due to the presence of static-mixers possessing structural elements .
BACKGROUND OF THE INVENTION
[0002] Static mixers or passive mixers find application in a wide range of process
operations, including dosing, dispersion, laminar flow heat-transfer, masstransfer, and reaction engineering. They are tried, and trusted devices for
combining liquids, gases, and powders in many industries. As the name goes by
the static mixers are devoid of moving elements and the mixing action is
achieved by the continuous splitting, combining, squeezing, twisting of the fluid.
Mixing action is accomplished by the inclusion of structural elements such as
vanes, plates, helical structures, arcs or by suitably modifying the geometry of
the static mixers that can be inserted into a conduit present in a housing
suitably, so as to increase the overall mixing of the multiphasic fluid under
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consideration. Twisting and splitting the flow by way of inclusion of a helical
structural element is an interesting way of obtaining intensified mixing using
static mixers. Literature search revealed many relevant prior art references
pertaining to the intensification of mixing efficiency of multiphasic systems
passively using static-mixers possessing structural elements.
[0003] Volker Hessel et al reviewed microstructured mixer devices and their
mixing principles concerning miscible liquids (and gases) and discussed various
passive mixing devices and techniques such as Y- and T-type flow-, multilaminating-, split-and-recombine-, chaotic-, jet colliding-, recirculation flowmixers and others (Chemical Engineering Science 60 (2005) 2479 – 2501).
[0004] Patent DE102017217683A1 disclosed a process for the preparation of
homogeneous mixtures of particulate components and apparatus for carrying
out the same.
[0005] Andrew N. Cookson, et al found that helical geometries such as stents
and shunts used as cardiovascular prosthetics could induce mixing effectiveness,
by embodying a ‘streamline crossing’ flow swirling flow, promoting in-plane
mixing ( Fluids 2019, 4(2), 59).
[0006] Patent DE102018104840A1 disclosed a mixer having a noncircular flow
cross-section fluid conduit to which the successive packages of fluids to be
mixed are deliverable.
[0007] Sheu, T.S et al described a novel parallel laminar micromixer with twodimensional staggered curved channels with tapered structures. The split
structures of the tapered channels resulted in the uneven split of the
mainstream and the reduction of the diffusion distance of two fluids. with
tapered structures. They found that the uneven split of two fluids inside the
staggered channels improved the mixing performance (Mixing of a split and
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recombine micromixer with tapered curved microchannels. Chemical Engineering
Science, 71, 321–332(2012).
[0008] Patent KR101999164B1 disclosed a nano bubble water generating tube
wherein a rotating body is formed by a hexagonal cylinder accommodating
therein and which is vertically movable along an upper portion of the upper
portion by screwing with an upper and an upper spiral portion formed with a
spiral portion on the outside and a driving shaft of a micromotor provided on the
upper surface of the rotating body.
[0009] Patent WO2009137457 disclosed a multi-phase fluid flow splitting device
that includes a feed pipe in which a flow redistribution element induces
tangential motion in the phases such that the denser phase is forced to
redistribute around the periphery of the feed pipe. The splitting is accomplished
by two helical vanes that ran parallel to the longitudinal axis.
[0010] Patent US5425581A disclosed a static mixer for mixing of different media
comprising mixing elements arranged within a tube, at which the mixing
elements are twisted to divide and divert the media wherein each mixing
element (1) is twisted 80°-100° and that every second mixing element (1) is
twisted counter clockwise while every other element is twisted clockwise.
[0011] Patent US4314974A disclosed a solvent extraction method using static
mixers wherein the liquids are initially mixed by flowing said aqueous solution
and said extraction liquid through a conduit containing a plurality of curved,
sheet-like elements extending longitudinally in said conduit and each having a
curvature to turn the direction phases flowing through said conduit, said
elements being arranged in alternating right-handed and left-handed groups, the
leading and trailing edges of adjacent elements being disposed at a substantial
angle with respect to each other.
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[0012] Still there is definitely a scope and necessity to come out with an
apparatus for passive mixing especially for the intensification of passive mixing of
a multiphase flow using such an apparatus. Hence this instant invention of
“Apparatus for passive mixing of multiphase flow” has been taken up. The
exemplary aspects of the invention are given in the summary of the invention
and are described in detail drawing reference to corresponding figures and
tables and experimental results in the detailed description section. The
various aspects of the instant invention of “ Apparatus for passive mixing of
multiphase flow” are definitely an improvement over the existing prior art and
definitely find application in processes dealing with liquid-liquid, liquid-liquid-gas,
immiscible fluid systems for the intensification of passive mixing and thereby
improving product yields, purity. The summary of the various embodiments of
the instant invention are given in the following paragraphs hereunder.

We Claim:
1. An apparatus for the passive mixing of a multi-phase(ic) flow or
hydrodynamic performance comprising a housing, having a conduit/tube or
a channel extending internally from the fluid inlet to the outlet ports that
comprises of stacked plurality of static-mixers possessing structural elements
or mixing elements on the inner walls of the individual static mixers that are
responsible for ellipsoidal-split-twist or split- cross twist of the multiphasic
flow through the conduit, bringing about the twisting effect on the flow
wherein,
a) The twisting is preceded by the splitting of the flow, resulting in an
enhanced mixing of the multi-phasic flow,
b) The conduit comprises of a stacked plurality of, static-mixers possessing
structural elements, across the length of the conduit that can allow the fluid
to pass through them continuously experiencing splitting and twisting and
combining, resulting in enhanced mixing, mass-transfer, and heat transfer,
c)The stacking of the individual static-mixers leaves gaps at regular intervals
at which places the split and twisted multiphasic flow combines and,
d) The multiphasic flow experiences a cumulative splitting-twistingcombining effect resulting in an enhanced overall mixing efficiency due to
plurality of static-mixers that are placed axially along the length of the
conduit.
2. The static mixer possessing structural elements responsible for ellipsoidalsplit-twist for mixing multiphase flow as claimed in claim 1 comprising of an
elliptical/circular cross-sectional flow area wherein the circular pipe cross-section
is first squeezed into a smaller elliptical cross-section, which then splits into two
identical radially symmetrical elliptical sub-sections.
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3. The static mixer possessing structural elements responsible for ellipsoidalsplit-twist for mixing multiphase flow as claimed in claim 1 wherein, the central
portion of the mixer involves a helical pathway traced by two elliptical subsections, the remainder of the length of the static mixer is used to bring the flow
back to its original configuration by combining the two sub-sections and then
expanding back to the pipe cross-section.
4. The static mixer possessing structural elements responsible for split- Crosstwist as claimed in claim 1 comprising of an asymmetric cross shaped cross
sectional flow area that is eccentric to the pipe’s central axis.
5. The static mixer possessing structural elements responsible for split- Crosstwist as claimed in claim 1 comprising of a circular pipe cross-section which is
first smoothly squeezed into a smaller” x” or asymmetric cross shaped crosssection.
6. The static mixer possessing structural elements responsible for split- crosstwist as claimed in claim 1 comprising of a central portion of the mixer involving
a helical pathway traced by the cross section wherein the remainder of the
length of the static mixer is used to bring the flow back to its original
configuration by expanding back to the pipe cross-section.
7. The enhancement of the mixing efficiency of the passive mixing of a multiphase(ic) flow by the apparatus comprising of stacked plurality of static-mixers
possessing structural elements responsible for ellipsoidal-split-twist as claimed in
claim 1 can be further enhanced by varying,
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a) The entry length and the exit length of the mixer according to the intended
working fluid,
(b)The aspect ratio of the initial cross-section to the subsections as defined by
the relation: Area of subsection∕ Area of initial cross-section,
(c)The splitting of the cross section into “n” number of channels, where n≥ 2,
(d)The cross-sectional split to asymmetric,
(e) The cross-section of the initial squeeze and the subsections of the area split
to be of different shapes,
(f) The placement of mixer elements to be eccentric to the axis of the pipe, or
the initial squeeze to be eccentric,
(g) The cross-section using an n-sided polygon, where n>3,
(h) The twist in the helical path by an angle θ, where 45° ≤ θ ≤ 315°,
(i)The pitch of the helix.
8. The enhancement of the mixing efficiency of the passive mixing of a multiphase(ic) flow by the apparatus comprising of stacked plurality of static-mixers
possessing structural elements responsible for split-cross-twist of the flow as
claimed in claim 1 can be further enhanced by varying,
a) The entry length and the exit length of the mixer according to the intended
working fluid,
b) The aspect ratio of the initial cross-section to the subsections as defined by
the relation: Area of the squeezed cross shape∕ Area of initial cross-section,
c) The cross-section shape to have ’ n’ number of limbs where n≥ 2,
d) The cross-section shape to eccentric or non-eccentric with respect to the
central axis,
e) The angle α of the cross limbs, where 120/n° ≤ α ≤ 360°(2/n – 1/3n), and n is
number of limbs,
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f) The twist in the helical path by an angle θ, where 45° ≤ θ ≤ 315°,
g) The pitch of the helix.
9. The multiphase (ic) flow as claimed in claim 1 selected from a group
comprising of liquid-liquid, liquid-gas, liquid-liquid-gas, immiscible solvent
systems, highly viscous liquids, liquid-solid, ternary systems, solvent-extractionsystems.
10. The apparatus as claimed in claim 1 for enhanced mixing of a multi-phasic
flow ensuring enhanced mass-transfer, heat-transfer and improved dispersion in
case of gas-liquid systems with minimal pressure head loss downstream of the
injection site.