U.S. patent number 3,652,061 [Application Number 05/120,873] was granted by the patent office on 1972-03-28 for interfacial surface generator and method of preparation thereof.
This patent grant is currently assigned to The Dow Chemical Company. Invention is credited to Douglas S. Chisholm.
United States Patent |
3,652,061 |
Chisholm |
March 28, 1972 |
INTERFACIAL SURFACE GENERATOR AND METHOD OF PREPARATION THEREOF
Abstract
A static element mixing tube is provided by employing opposed
angularly disposed baffles of alternating hand which provides
mixing action by re-positioning of the stream. Mixing action at
flow rates below the turbulent level are generally independent of
throughput.
Inventors: |
Chisholm; Douglas S. (Midland,
MI) |
Assignee: |
The Dow Chemical Company
(Midland, MI)
|
Family
ID: |
22393033 |
Appl.
No.: |
05/120,873 |
Filed: |
March 4, 1971 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
583 |
Jan 5, 1970 |
|
|
|
|
Current U.S.
Class: |
366/337 |
Current CPC
Class: |
B01F
5/0619 (20130101) |
Current International
Class: |
B01F
5/06 (20060101); B01f 015/02 () |
Field of
Search: |
;259/4,18,36,60,2 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Jenkins; Robert W.
Parent Case Text
This application is a continuation of my earlier filed application
Ser. No. 583 filed Jan. 5, 1970, now abandoned.
Claims
What is claimed is:
1. An interfacial surface generator comprising a hollow tubular
conduit defining an internal longitudinal passageway, the conduit
having a wall, a first pair of opposed plate-like elements disposed
in angular relationship to the longitudinal axis of the conduit to
form a first baffle, the plate-like elements having at least one
inwardly disposed edge, the edges of the first and second
plate-like elements being in closely adjacent relationship, the
first baffle being of right-handed configuration, a second baffle
adjacent to the first baffle, the second baffle being of like
construction to the first baffle with the exception that the
plate-like elements are disposed in left-handed configuration and
the edges thereof being angularly disposed about the axis of the
conduit relative to the edges of the plate-like element of the
first baffle, a third baffle of plate-like elements of similar
construction to the first baffle disposed adjacent the second
baffle and remote from the first baffle and the plate-like elements
having about the same angular relationship relative to the axis of
the conduit as the first baffle.
2. The generator of claim 1 wherein the plate-like elements are
affixed to the conduit.
3. The generator of claim 2 wherein the plate-like elements are
secured within slots in the conduit wall.
4. The generator of claim 1 wherein the conduit has a generally
circular cross-sectional configuration.
5. The generator of claim 4 wherein the plate-like elements have a
generally hemielliptical configuration.
6. The generator of claim 1 including a generally axially extending
rod-like element disposed between adjacent pairs of plate-like
elements.
7. A method for preparing an interfacial surface generator, the
steps of the method comprising
providing a hollow tubular conduit having a wall,
forming first and second slots in the wall of the conduit, the
first and second slots being generally diametrically opposed, the
first and second slots being disposed at an angle of substantially
less than 90.degree. at the longitudinal axis of the conduit, the
first and second slots in an orthographic projection of an end view
of the planes thereof being disposed in angular relationship to
each other,
providing first and second plate-like elements,
disposing said first and second plate-like elements in the first
and second slots, respectively,
affixing the plate-like elements in generally sealing engagement to
the wall of the conduit to provide a first baffle arbitrarily
designated as a right-handed baffle,
forming within the wall of the conduit adjacent the first baffle
third and fourth slots, the third and fourth slots being disposed
generally similarly to the first and second slots but rotated about
the axis of the conduit and of opposite hand to the first and
second slots,
disposing third and fourth plate-like elements within the third and
fourth slots in the conduit wall,
forming fifth and sixth slots generally adjacent to the second and
third slots and remote from the first and second slots, the fifth
and sixth slots being oriented generally as the first and second
slots, disposing fifth and sixth plate-like elements within the
fifth and sixth slots and affixing them to the conduit wall to form
a third baffle of generally right-handed configuration, the second
baffle having a generally mirror image configuration to the first
and third baffles.
8. An interfacial surface generator comprising a hollow tubular
conduit defining an internal longitudinal passageway, the conduit
having a wall, a first plurality of opposed plate-like elements
disposed in angular relationship to the longitudinal axis of the
conduit to form a first baffle, the plate-like elements having at
least one inwardly disposed edge, the edges of the first plurality
of elements being in closely adjacent relationship, the first
baffle being of right-handed configuration, a second baffle
adjacent to the first baffle, the second baffle being of like
construction to the first baffle with the exception that the
plate-like elements are disposed in left-handed configuration and
the edges thereof being angularly disposed about the axis of the
conduit relative to the edges of the plate-like element of the
first baffle, a third baffle of plate-like elements of similar
construction to the first baffle disposed adjacent the second
baffle and remote from the first baffle and the plate-like elements
having about the same angular relationship relative to the axis of
the conduit as the first baffle.
9. A method for preparing an interfacial surface generator, the
steps of the method comprising
providing a hollow tubular conduit having a wall,
forming a first plurality of slots in the wall of the conduit, the
first plurality of slots being generally radially disposed, the
first plurality of slots being disposed at an angle of
substantially less than 90.degree. at the longitudinal axis of the
conduit, the first plurality of slots in an orthographic projection
of an end view of the planes thereof being disposed in angular
relationship to each other,
providing a first plurality of plate-like elements,
disposing said first plurality of plate-like elements each in a
slot of the first plurality of slots,
affixing the plate-like elements in generally sealing engagement to
the wall of the conduit to provide a first baffle arbitrarily
designated as a right-handed baffle,
forming within the wall of the conduit adjacent the first baffle a
second plurality of slots, the second plurality of slots being
disposed generally similarly to the first plurality of slots but
rotated about the axis of the conduit and of opposite hand to the
first plurality of slots,
disposing a second plurality of plate-like elements within the
second plurality of slots in the conduit wall,
affixing the second plurality of elements to the conduit wall
forming a third plurality of slots generally adjacent to the second
plurality of slots and remote from the first plurality of slots,
the third plurality of slots being oriented generally as the first
plurality of slots,
disposing a third plurality of plate-like elements within the third
plurality of slots and affixing the third plurality of elements to
the conduit wall to form a third baffle of generally right-handed
configuration, the second baffle having a generally mirror image
configuration to the first and third baffles.
Description
This invention relates to an interfacial surface generator and a
method for the preparation of interfacial surface generators.
The term "interfacial surface generator" is employed herein to
describe a static mixing element through which a stream of liquid
gas or particulate solids may be passed and the configuration of
the generator is such that the stream is divided and recombined to
provide mixing. Several varieties of such mixers are known and
disclosed in the following U.S. Pat. Nos. 3,051,452; 3,051,453;
3,182,965; 3,195,865; 3,206,170; 3,239,197; 3,286,992; 3,328,003;
3,358,749; 3,394,924; 3,404,869; 3,406,947; also of interest is
French Pat. No. 735,033 (1932). All of the above patents are
herewith incorporated by reference. Such interfacial surface
generators are generally obtained by providing a baffle or
stream-deflecting element of a specific configuration within a
conduit or passageway. Frequently such interfacial surface
generators require machine or block molding, casting or sheet
fabrication to obtain baffles of the desired configuration. U.S.
Pat. No. 3,358,749 and No. 3,394,924 disclose the preparation of
interfacial surface generators by the deformation of tubes.
Deformation of tubes most often is suitable for mixers employing
low pressure and relatively small diameters. The preparation of
mixers of large diameter has generally been limited to the
insertion of preformed baffle sections such as are disclosed in
U.S. Pat. No. 3,051,452 and the like. Often times when baffles are
inserted within a conduit, substantial difficulty is encountered in
securing the baffles in the desired position where access to the
inside of the tube for fabrication purposes is not readily
available.
It would be desirable if there were available an interfacial
surface generator prepared from a conduit and plate-like
elements.
It would also be desirable if there were available an interfacial
surface generator prepared from a tubular conduit wherein the
plate-like elements are firmly secured to the wall of the
conduit.
It would also be desirable if there were a simple method available
for the preparation of an interfacial surface generator by simple
fabricating techniques.
These benefits and other advantages in accordance with the present
invention are achieved in a method for preparing an interfacial
surface generator, the steps of the method comprising providing a
hollow tubular conduit having a wall, forming a first plurality of
slots in the wall of the conduit, the first plurality of slots
being generally radially disposed, the first plurality of slots
being disposed at an angle of substantially less than 90.degree. to
the longitudinal axis of the conduit, the first plurality of slots
in an orthographic projection of an end view of the planes thereof
being disposed in angular relationship to each other, providing a
first plurality of plate-like elements, disposing said first
plurality of plate-like elements each in a slot of the first
plurality of slots, affixing the plate-like elements in generally
sealing engagement to the wall of the conduit to provide a first
baffle arbitrarily designated as a right-handed baffle, forming
within the wall of the conduit adjacent the first baffle a second,
third and plurality of slots, the second plurality of slots being
disposed generally similar to the first plurality of slots but
rotated about the axis of the conduit and of opposite hand to the
first and second slots, disposing a second plurality of plate-like
elements within the second plurality of slots in the conduit wall,
affixing the second plurality of elements to the conduit wall,
forming a third plurality of slots generally adjacent to the second
plurality of slots and remote from the first plurality of slots,
the third plurality of slots being oriented generally as the first
plurality of slots, disposing a third plurality of plate-like
elements within the third plurality of slots and affixing them to
the conduit wall to form a third baffle of generally right-handed
configuration, the second baffle having a generally mirror image
configuration to the first and third baffles.
Also contemplated within the scope of the present invention is an
interfacial surface generator comprising a hollow tubular conduit
defining an internal longitudinal passageway, the conduit having a
wall, at least a first plurality of generally opposed plate-like
elements disposed in angular relationship to the longitudinal axis
of the conduit to form a first baffle, the plate-like elements
having at least one inwardly disposed edge, the edges of the first
plurality of plate-like elements being in closely adjacent
relationship, the first baffle being arbitrarily designated as
being of right-handed configuration, a second baffle adjacent to
the first baffle, the second baffle being of like construction to
the first baffle with the exception that the plate-like elements
are disposed in left-handed configuration and the edges thereof
being angularly disposed about the axis of the conduit relative to
the edges of the platelike element of the first baffle, a third
baffle of plate-like elements of similar construction to the first
baffle disposed adjacent the second baffle and remote from the
first baffle and the plate-like elements having about the same
angular relationship relative to the axis of the conduit as the
first baffle.
Further features and advantages of the present invention will
become more apparent from the following specification taken in
connection with the drawing wherein:
FIGS. 1, 2 and 3 schematically depict three views of one embodiment
of the invention.
FIGS. 4, 5, 6 and 7 depict end views of alternate embodiments of
the invention.
In FIGS. 1 and 2 are depicted schematically cutaway views of a
mixer generally in accordance with the invention designated by the
reference numeral 10. FIGS. 1 and 2 are side views of a mixer
wherein the mixer is rotated 90.degree. about the longitudinal axis
relative to the other view. The mixer 10 comprises in cooperative
combination a generally cylindrical hollow body 12, the body 12
having a wall portion 13, a first end 14, a second end 15. The body
12 defines an internal longitudinally extending passageway 17.
Generally adjacent the first end 14 of a conduit 20 a first slot 18
is defined in the wall 13. The slot 18 is generally angularly
disposed relative to a longitudinal axis A of the conduit 12 and
angularly disposed to a plane normal to the axis A. The first
baffle 19 is disposed within the slot 18 and affixed therein in
generally sealing engagement. The baffle 19 defines a first or
inwardly projecting edge portion 21 and an external edge portion 22
having a generally hemielliptical configuration. A second slot 25
is oppositely disposed from the slot 18 having a generally like
angular configuration with respect to the axis A and a plane normal
to the axis A when viewed in a generally radial direction and has
disposed therein a second plate-like element 26 having an internal
edge 27 of generally linear configuration and an external edge 28
of generally hemielliptic configuration. The plate-like elements 19
and 26 in cooperative combination form a first baffle generally
designated by the reference numeral 30. Adjacent the first baffle
30 a housing 12 defines a first slot 31 and a second slot 32. The
slots 31 and 32 are angularly disposed with relationship to each
other to the axis A and to a plane normal to the axis A of the
conduit 12. Relative to the first and second slots 18 and 25, the
slots 31 and 32 are rotated at an angle about 90.degree. about the
axis A and are of opposite hand to the slots 18 and 25 and form a
configuration of opposite hand to that formed by the slots 18 and
25. A third plate-like element 33 of generally like configuration
to the baffle 19 is disposed within the slot 31. The baffle 33 has
a generally linear edge 34 disposed within the passageway 17 and a
generally hemielliptical edge 35 in generally sealing engagement
with the wall 13 of the conduit 12. A fourth plate-like element 37
is disposed within the slot 32 generally opposite the third
plate-like element 33. The third plate-like element 33 has an
inwardly disposed linear edge 38 and a second generally
hemielliptical edge 39 in generally sealing engagement with the
wall 13 of the conduit 12 thereby providing a second or left-handed
baffle assembly generally designated by the reference numeral 40.
Adjacent to the baffle assembly 40 and remote from the baffle
assembly 30 is a baffle assembly 41 of similar structure and
orientation to the baffle assembly 30.
Thus, mixers in accordance with the present invention generally
comprise alternating baffle assemblies of like configuration
wherein one set of baffle assemblies are right-handed
interdigitated with left-handed baffle assemblies whose generally
linear edges are rotated about the axis of the conduit. Such
angular deviation for many applications is 90.degree. but may vary
between 30.degree. to 160.degree.. It is essential and critical to
the operation of the present invention that the plate-like elements
making up the baffle assembly be disposed at an angular
relationship to both the longitudinal axis and to a plane normal to
the longitudinal axis. The angular deviation of the linear edge
such as the linear edges 21, 27, 34 and 38 usually is between about
30.degree. and 70.degree., and beneficially between about
35.degree. and 55.degree., the deviation being measured by the
angular displacement of the linear edge to the longitudinal axis of
the conduit. For a tube of given diameter, the greater the angular
deviation, the more baffle units per unit length may be formed and
thus an increased number of mixing stages may be obtained. However,
employing a lesser angle, higher flow velocities are utilized
before turbulent flow occurs.
FIG. 3 depicts an end view of the baffle assembly 30 of FIG. 1
depicting the relationship between the plate-like elements 19 and
26.
In FIG. 4 there is depicted an end view of an alternate embodiment
of the invention generally designated by the reference numeral 45.
The embodiment 45 comprises a generally cylindrical conduit 12a, a
plurality of baffle assemblies each consisting of a pair of opposed
plate-like elements 46 and 47 oppositely disposed in alternating
pairs such as the apparatus of FIG. 1 wherein each of the
plate-like members terminate in an edge 48 and 49, respectively,
which define, when axially viewed, a generally circular opening 51
between the adjacent edges 48 and 49 of the plate-like elements 46
and 47. Such an embodiment is particularly advantageous when rapid
assembly is desired. For example, a solid rod or conduit may be
disposed between adjacent plate-like elements to provide indexing
therefor during fabrication. The rod or conduit may be subsequently
removed, or when a conduit is employed it may be left in position
as depicted by the conduit 52 of FIG. 4 and utilized for heat
exchange purposes. Alternately, baffles may be assembled to a rod
or conduit and subsequently inserted into a surrounding conduit
such as the conduit 12a where pressure drops are relatively low.
Support of plate-like elements may be entirely from the central rod
or conduit 52. In instances where higher pressure drops are
encountered, the baffles should be affixed to the external conduit
such as the conduit 12a.
In FIG. 5 there is depicted an alternate embodiment of the
invention generally designated by the reference numeral 55
comprising a generally cylindrical conduit 12b having a plurality
of plate-like elements having a similar arrangement to that of FIG.
1 wherein the plate-like elements comprises a first or large
element 56 and a second or smaller element 55, the element 56 being
a portion of an ellipse somewhat greater than a hemiellipse and
terminating in a straight edge 58, whereas an element 57 comprises
the remaining portion of the ellipse from which the element 56 may
have been cut and terminates in a straight edge 59. The lines
designated by the reference numeral 61 represent the positioning of
the linear edges of the second and fourth baffles of a mixer having
the repeating pattern shown in FIG. 1 and the plate-like element
configuration of FIG. 5, and the dotted line designated by the
reference numeral 62 represents the edges of the plate-like
elements forming third, fifth, seventh . . . and like baffles.
The embodiment of FIG. 5 is applied with particular benefit when
such a mixer is employed with viscous materials which have a
tendency to be unmixed in the central portion thereof.
An alternate embodiment of the invention is depicted in FIG. 6
generally designated by the reference numeral 65. The mixer 65
comprises a hollow rectangular tube 67 having disposed therein a
first generally plate-like element 68 angularly disposed therein
generally in the manner of the element 19 of FIG. 1 and a second
plate-like element 69 which generally corresponds to the element 26
of FIG. 1. A third plate-like element 71 is disposed behind the
element 68 in a configuration generally similar to that of the slot
31 of FIGS. 1 and 2. A fourth element 72 corresponding to the
element 32 of FIGS. 1 and 2 is disposed adjacent the element 71. A
gap 73 is defined by the first element pair 68 and 69. A similar
pair 74 is defined between the elements 71 and 72. The gaps 73 and
74 are disposed generally at right angles to each other and
generally bisect the opposing sides of the elements 68 and 69. The
embodiment 65 is particularly advantageous wherein maximum mixing
of the stream is required adjacent the outer portions thereof and
minimal mixing toward the center. A typical application of such a
mixer is the application of a graded coating in a generally axial
direction on a wire or conduit. Typically, feeding such a mixer is
done by providing a coaxial stream of diverse materials wherein a
component desired to be in contact on a body such as a conduit or
wire is centrally disposed, the material which is desired to form
the external surface is peripherally disposed, the wire conduit and
stream passed through the mixer wherein the wire or conduit passes
through the common portion of the gaps 73 and 74 and the coaxial
streams intermixed in the region of their interface to a desired
degree dependent on the number of baffle stages through which the
stream passes.
In FIG. 7 there is schematically depicted an end view of an
alternate embodiment of the mixer of the invention generally
designated by the reference numeral 80. The mixer 80 comprises a
first or outer conduit 81 and a second or inner conduit 82. The
conduits 81 and 82 are generally coaxially arranged. The first
baffle of the mixer 80 employs three plate-like elements 83, 84 and
85, each having a semi circular configuration. Each of the elements
83, 84 and 85 lies in a plane of generally like angular disposition
to the axis of conduits 81 and 82 generally in the manner of the
elements of FIG. 1. Elements 83, 84 and 85 are circumferentially
disposed within slots (not shown) in the conduit 82 to provide an
angular circumferential spacing of about 120.degree.. Additional
trifoliate baffles of alternating hand (not shown) are provided
generally arranged as the baffles of FIGS. 1 and 2 wherein the
leading edge of each element is positioned generally midway
(angularly when viewed along the conduit axis) between two trailing
edges of elements of an immediately adjacent baffle. In preparing a
mixer in accordance with FIG. 7, the elements may be affixed in the
wall of conduit 82 and the resultant structure inserted into
conduit 83 and optionally affixed to conduit 83 by welding
adhesives or the like. Alternately, the elements are inserted in
slots in both conduit walls and affixed by suitable means such as
brazing adhesives and and the like.
The embodiment of FIG. 7 is particularly well suited for heat
exchange application wherein it is desired to obtain a uniform
temperature in a viscous liquid. Beneficially, the viscous liquid
is passed through conduit 82 and the heat exchange liquid passed
between conduits 81 and 82 either concurrently or in a
countercurrent direction.
In a similar manner mixers are readily prepared employing 4, 5, 6
and more elements per baffle.
The interfacial surface generators in accordance with the present
invention are particularly advantageous in that they may be readily
fabricated from almost any material which includes glass, metal,
thermoplastics, thermosetting resins, glass fiber reinforced
thermosetting resins and the like. Preparation of such mixers is
readily accomplished with tube and sheet stock wherein the tube is
slotted, the sheet-like elements secured in the slots by a suitable
means such as adhesives, fusion welding, brazing, soldering or
other joining means appropriate to the material employed. In
forming a mixer from a round conduit, each of the plate-like
elements of a pair may have a fractional elliptical configuration
or they may be rectangular if desired and the portion of the
elements extending beyond the conduits employed as a support for
the finished mixer.
Mixers in accordance with the present invention are useful for the
mixing of solids, liquids, gases and the like. When employed to
blend streams of particulate solids, it is not necessary that a
liquid-tight connection be made between the plate-like elements and
the conduit, but only that any gaps appearing between the tube and
the plate-like elements should be of a dimension sufficiently small
to prevent escape of the materials being handled. The present
invention is particularly desirable in that for mixing liquids
under pressure, metallic pipe such as steel or stainless steel is
readily slotted, the plate-like elements inserted and welded in to
provide a structure at least of equal bursting strength to the
original pipe.
As is apparent from the foregoing specification, the present
invention is susceptible of being embodied with various alterations
and modifications which may differ particularly from those that
have been described in the preceding specification and description.
For this reason, it is to be fully understood that all of the
foregoing is intended to be merely illustrative and is not to be
construed or interpreted as being restrictive or otherwise limiting
of the present invention.
* * * * *