Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROllND OF THE INVE~TION
Field of t~e Invention
The present invention relates to mixing techniques and
devices. More particularly, the present invention relates to a
method and apparatus for mixing a highly viscous fluid mass by
altering the flow pattern of a viscous fluid stream so as to
generate interfacial surfaces in the fluid mass.
The Prior Art
The thorough mixing of extremely viscous material has
been a problem of considerable commercial concern. One approach
to mixing viscous materials involves transporting a viscous
fluid mass through a conduit containing baffles or other ob-
structions which serve to split the stream of fluid materials
flowing through the conduit, effectively spreading the stream
out and creating a large surface area, and then combining the
streams again in an overlapped type of relationship so as to
provide relatively efficient mixing without turbulence and in-
dependent of the flow rate of the reacting stream. Typical of
such devices are those described in U.S. Patent 3,239,197 of
James E. Tollar issued 8 March 1966 and U.S. Patent 3,664,638
of Kenneth M. Grout and Richard D. Devellin issued 23 May 1972,
for example. Among the deficiencies of the type of mixing de-
vices just mentioned are the relatively large pressure drops
associated with extensive internal baffles and the difficulty
of cleaning such devices particularly when the fluid mass is a
highly reactive material such as a thermoset resin which rapidly
sets and cures into a solid mass.
SUMMARY OF THE INVENTION
In its simplest sense, the present invention pro-
vides a method for mixing a stream of fluid mass, particu-
larly a viscous fluid mass, by dividing the stream of fluid
mass into a plurality of substreams, imparting a predeter-
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1 ~hrnFd rotational flow pattern in a first direction to alter-
2 nate substreams and imparting a predetermined rotational
3 flow pattern opposite in direction to said first direction
4 to the remaining substreams.
In a preferred embodiment of the present invention,
6 a hi~hly viscous fluid is mixed by establishing a stréam of
7 fluid mass. This stream is divided into a plurality of sub-
8 streams by subjecting said stream of fluid mass to the
9 impingement of a plurality of jets of high pressure fluid,
preferably a gas, at predetermined points along the stream
11 of fluid mass. A predetenmined rotational flow is imparted
12 in a first direction to alternate substreams, for example,
13 substream 1, 3, 5, 7, etc. by subjecting these alternate
14 substreams to a tangentially impinging jet of the high
pressure fluid. The remaining substreams, for example,
16 substream 2, 4, 6, 8, etc. are rotated in a predetenmined
17 flow opposite in direction to the first rotational direction
18 by the tangential impingement of a jet of the high pressure
19 fluid. ~
In another embodiment of the present invention,
21 a static mixer is provided for mixing very viscous and even
.
22 rapidly reacting materials. The mixing device consists of
23 an elongated tube or conduit through which the reactant
24 materials are forced. Based at predetermined locations
along the elongated tube are a plurality of means for intro-
26 ducing a jet of a high pressure fluid, preferably a gas, at
27 substantially rLght angles to the longitudinal axis of the
'28- -5tub~so as to divide a stream of reactant materials into a
29 plurality of substreams. Also spaced at predetermined loca-
tio~s^ along the elongated tube or conduit are a plurality of
31 means for introducing jets of the same or different high pres-
32 surel fluid substantially tangential~to the--inner surface of the
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1 elongated tube or condui~. Preferably the elongated tube or
2 conduit has a circular cross-section. Also, preferably the
3 means for introducing jets of high pressure fluid are spaced
4 at substantially equal distance along the ëlongated tube.
Preferably, each means for introducing a jet of high pressure
6 fluid is based at right angles with respect to the next
7 successive means for introducing a jet of high pressure
8 fluid.
9 In a particularly preferred embodiment of the pre-
sent invention, a stream of highly viscous material is forced
11 through a conduit or pipe. This stream is divided into a
12 plurality of substreams by means of the impingement of a jet
13 of hlgh pressure fluid, such as air, which is introduced
14 through a nozzle means located at substantially right angles
to the longitudinal axis of the pipe at a plurality of loca-
16 tions along the periphery of the pipe. The alternating sub-
17 streams are given a rotational motion in a first direction
18 by introducing a high pressure fluid, such as air, tangential
19 to the inner periphery of the pipe. The remaining substreams
are given a rotational motion opposite to the first direc-
21 tion by the introduction of a high pressure fluid, such as
22 air, tangential to the inner periphery of the pipe by a
23 plurality of nozzle means located along the periphery of the
24 pipe.
The broad outline of the method and apparatus of
26 the invention will be more clearly understood from the de-
27 tailed description which follows, taken with the accompany-
28 ing drawings.
29 BRIEF DESCRIPTION OF THE DRAWINGS
.
Figure 1 is a perspective and isometric view of a
31 simple form of device according to the present invention.
- 32 ~ - Figure 2 is an enlarged partial view, partly in
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section, diagrammatically show~ng the fluid flow in the device
of Figure 1._
Figure 3 is a cross-sectional along lines 3-3 of Figure
1 partly cut away and partly showing the directional motion of
the impinging fluid streams.
Figure 4 which appears on the first sheet of drawings,
is a side elevation of a nozzle used for introducing a high
pressure fluid tangential to the inner surface of the device
according to the present invention.
Figure 5, which appears on the first sheet of drawings,
is a side elevation of a nozzle used for dividing the stream of
fluid mass into substreams in accordance with the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
_ .
A particularly desirable application of the present
invention is in rapidly mixing extremely viscous reactive
materials such as a foamable liquid resin composition, parti-
cularly a foamable resin composition containing reinforcing
fibers, solid fillers and the like. Thus, the present inven-
tion will be described with reference to this particular desir-
able application. It should be understood, however, that the
invention is not intended to be limited strictly to the specific
embodiments shown and described herein but may be modified ex-
tensively while still within the spirit of the present invention.
In preparing a fiber-reinforced plastic foam it is
~ necessary to introduce resin precursors premised with fiber-
; glass and other reinforcing material into the mixer simul-
taneously with a catalyst (if desired), blowing agents and
other ingredients desired. These reactant materials must
be mixed thoroughly and rapidly since within a very short
period of time they will begin to react. Accordingly, they
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must be quickly placed in a mold immediately after mixing
so the foaming process may occur therein. Thus,
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1 referring to the drawings and particularly to Figure 1, a
2 mixer embodying the invention is indicated generally at 12.
3 A stream of viscous material of the type mentioned above is
4 shown as line 10 entering opening 15. Precisely predeter-
mined quantities of viscous materials can be supplied to the
6 mixing device 12 by means of precision volumetric control
7 pumps and the like (not shown).
8 In any event, the viscous stream of material
9 enters the first passageway at 15 and is caused to flow
through the elongated tube or conduit 11 of mixer 12 by a
11 ram or plunger of a pumping device, for example.
-12 As can be seen in Figure 1, the mixing device is
13 an elongated tube or conduit 11 which has a first end 14 and
14 a second end 16. In a preferred embodiment of the present
invention the mixer 12 is provided with a mounting flange
16 17 for operatively connecting the inlet end of the mixer
17 to a metering and pumping system. ThUSJ as is shown,
18 entrance passages 18 and 19 are provided for the flow of
19 liquid reactants from meters and pumps ~not shown) into the
principle flow passage of mixer 12 through opening lS at
21 first end 14. Thus, flange 17 provides a convenient mount-
22 ing means for mounting the mixer and a suitable entrance
23 support system having a corresponding flange such as flange
24 20.
As can be seen, the mixer 12 is also provided with
26 a second flange 21 at second end 16 for cooperatively mount-
27 ing with any desired distribution system. ThUSJ elbow 22 is
28 mounted on a flange 23 and when operatively connected with
29 mixer 12, the thoroughly mixed stream o material exiting
the mixer at second énd 16 can be dischargedJ for example,
31 downwardiy onto a suitable mold (not shown).
32 At various intervals along the length of mixer 12
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1 are a series of mounting blocks 24 for supporting the mlxer
2 in a suitable position. Other mounting means, of course,
3 can be employed.
4 Spaced along the conduit or elongated tube 11
which forms the central mixing chamber 12 of the present
6 invention are a plurality of nozzle means for introducing
7 a high pressure fluid into the reactor substantially radi-
8 ally so as to divide a stream of material flowing through
9 the mixer into a plurality of substreams. These dividing
means are shown as nozzles Bl, Dl, B2 and D2 in Figure 1.
11 As can be seen in Figure 3, it is preferred that each
12 dividing nozzle be substantially at 180 with respect to
13 the next dividing nozzle. Thus, Dl is on the opposite side
14 of the tubular body portion 11 of mixer 12 than Bl, but
spaced further along the longitudinal axis.
16 Further in accordance with the preferred embodi-
17 ment of the present invention as shown in Figure 5, the
18 dividing nozzles or jet fit~ings such as Bl are inclined
19 generally at an angle, ~, of about 10 with respect to the
radius of the tubular body portion so as to deliver a jet
21 of high pressure fluid that has both a forward component
22 as well as a radial component, for the purposes hereinafter
23 discussed.
24 Returning again to Figure 1, it can be seen that
the plurality of means for introducing a high pressure fluid
26 tangential to the periphery of the main tubular section of
27 mixer 12 is provided. These fluid stream rotating nozzles
28 are designated as Al, Cl, A2 and C2 in the figure. As can
29 be seen particularly with regard to Figure 3, these nozzles,
Al and Cl for example, are arranged on opposite sides of the
31 main tubular body portion of mixer 12. Thus, as can be seen
32 in Figure 2, these nozzle fittlngs also are inclined at an
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1 angle, ~, of about 10 with respect to the radius of the
2 main tubular section so as to impart a high pressure rota-
3 tion fluid stream having both a forward component and a
4 tangentiat component thereby rotating a substream in a
clockwise or counterclockwise fashion. Indeed, thé tangen-
6 tial component is so arranged that alternating nozzles will
7 have a first tangential entry direction and the remaining
8 will have a second tangential direction opposite from said
9 first tangential direction.
In Figure 3, lines 1, 2, 3 and 4, diagrammatically
11 depict the general directional movement of the high pressure
- 12 fluid introduced via each respective nozzle. Thus, the high
13 pressure fluid introduced via fluid stream divider nozzles
14 Bl and Dl enters generally radially as is indicated by lines
1 and 2 respectively. The high pressure fluid introduced
16 via the tangential nozzles Al and Cl have opposite rotation-
17 al directions shown by lines 3 and 4 respectively. Thus,
18 the rotational direction of fluid entering via Cl is clock-
19 wise whereas the rotational direction of fluid entering via
Al is counterclockwise. This clockwise, counterclockwise
21 rotational direction is also shown in Figure 2.
22 The number of nozzles for dividing a main stream
23 and the number of nozzles to provide substreams and the
24 number of nozzles for rotating the various substreams may be
varied to give the desired performance for any specific
26 viscous liquid mixing problem. As should be appreciated,
27 the apparatus a1~so may be constructed from any of a wide
28e vari`ety of materiàls~r~nclud~ng~metal and the like, the choice
29 of materials being predicated upon the particular conditions
which will be encountered in the situation for which ~he
31 apparatus is designed.
32 ~ ~ As is shown in the drawings, and in particul*r inr ~ ~
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1 Figures 4 and 5, the var~ous nozzle means include threaded
2 inserts for suitably connecting the nozzle means to a source
3 oi! high pressure fluid. Thus, threads 32 permit easily
4 connecting a source of high pressure fluid to the mixer.
Also threads 33 permit easy removal of the insert portion
6 for cleaning, if necessary, of the radially directing
7 opening 31 of Bl and the tangential opening 35 of Al.
8 Generally, in the practice of the present inven-
9 tion the high pressure fluid employed will be a gaseous
material such as air or nitrogen; however, the fluid mater-
11 ial introtuced under high pressure may also be one of the
12 components of the main fluid stream to be mixed.
13 The operation of all or any of the previously
14 illustrated embodiments of the present invention and the
method thereof is substantially achieved as follows:
16 (a) A stream of relatively viscous material is
17 established by introducing the material to be mixed at first
18 end 14 of the mixer 12. For example, polyurethane resin
19 precursor with fiberglass is metered and introduced through
passageway 18 and catalyst and blowing agent is metered and
21 introduced via passage 19 thereby establishing stream 10
22 for a transversed flow through .the tubular conduit 11 of
23 mixer 12.
,:
24 (b) The main stream thus established is divided
into a plurality of substreams by the high pressure fluids
26 introduced at spaced predetermined positions along the
27 longitudinal axis of the mainlstream and subs~antially
28 radial thereto, for éxample-,~v~a Bl, Dl, :~2 and D2-
29 (c) The substreams are then rotated in a prede-
termined flow pattern by the h~igh pressure fluid introduced
31 tangentially at spaced predetermined positions along the
32 ..1~ng.itudinal axis of the main-s~tream, or example, vi~..~..e...~.. ..
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1 Al, Cl, A2 and D2. It should be noted that alternate sub-
2 streams have imparted to them a first predetermined rota-
3 tional flow pattern in a first direction which is opposite
- 4 to the predetermined rotational flow pattern imparted to the
remaining substreams. Thus, for example, a plurality of
6 substreams will be given a clockwise rotational motion while
7 alternate substreams will be given counterclockwise rota-
8 tional motion.
9 The net effect of dividing the stream of viscous
material into substreams and rotating the various substreams
11 in opposite directions is to continually divide and recom-
12 bine the substreams so that complete mixing is achieved.
13 Thus, the viscous material is forced to flow through a
14 serpentine path without being in contact with dams or
baffles or other such internal arrangements. Thus, in the
16 case of forming a foamable resin composition of the type
17 which will typically foam and begin to set within about 30
18 seconds after the foam components begin to come into con-
19 tact with each other, the device of the present invention
offers considerable advantage in regard to cleaning the
21 mLxer fter each use.
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