Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS AND PROCESS FOR METERI~G AND
~ XING LIQUIDS IN ARBITP~RY. ~SS PROPORTIONS
Bac~ground of the Invention
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The present invention relates to fluid control
and in particular to liquid-liquid mixtures.
Liquid-liquid mixers have been used by such
diverse groups as the chemical process industries and
by home owners in dispensing liquid fertilizer. In
l general the systems heretofore available are directed
L0 ll toward producing constant liquid-liquid volume ratios,
~e for example U.S. Patent 3,188,055. In chemical process
industries where liquid streams are proportiona,ely mixed, I
deviations in constant liquid-liquid ratios occur due
to the valve and nozzle flow characteristics controlling
L5 the streams or due to pressure deviations in the regulating
valves. In these systems the pressure proportionate band
is inherently fixed to the pressure of the primary liquid
to which one or more liquids are to be mixed as well as
the mass of the liquids flowing.
:20 A problem exists in the utilization of the mixtures
of certa`inliquid fuels, such as synthetic or biomass fuels
and fuel oils, which are to be used in existing energy
systems such as boilers and engines. In these cases the
stagnation pressure and/or mass flow of the fuels is
modulated depending on load demands.
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In order to operate these energy systems efficiently,
and in order to maintain or extend the range of the
operating characteristics of these systems as well as
to optimize the performance of these systems while
utilizing fuel mixtures, the liquid-liquid mixture ratios
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must be varied according to the operating characteristics
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I of the energy devices. As a result, a need has arisen
¦ for an improved liquid-l~quid mixing device capable of
I providing liquid mixtures in any predetermined proportions
i (within determined limits) while both the stagnation
pressure and mass flow of the primary liquid are varying. ',
~ ~ In view or the above, it is he principal object
:'! j of thë present invention to provide an improved mixing
l process and mixing device for attaining the above result.
1 It is a further object of this invention to
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provide a process and apparatus which can be completely
passive and requires no external power or signal so~Irce.
Another object of this invention is to be able
to inject a secondary liquid at low stagnation pressure
i 20 l into a primary liquid at high stagnation pressure.
A still further object of this invention is to
¦ provide a process and apparatus which can be incorporated
into existing vehicles or power plants with a minimum of
downtime or expense.
Yet another object of this invention is to
provide an active means to adjust the stagnation pressures
,i of the secondary liquids such that a completely arbitrary
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metering-mixing ratio schedule is achieved with varying
mass flow and/or stasnation pressure of the primary liquid.
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~Summary Olc the Invention
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The above and other beneficial objects and
adva~ges are attained in accordance with the present
invention by providing a method for obtaining through a
passive device various liquid-liquid mixture ratios of
- I a primary liquid and secondary liquids during pressure
¦ and mass flow modulation of the primary liquid. The
10passive device includes a first section so dimensioned
that a significant decrease in pressure occurs in the
primary liquid as it flows through the first section.
A second section, essentially constant in cross section
or of gently varying cross sectional area, is connected
~' 15to the first section with-smooth transition A decrease
in pressure occurs in the flowing primary liguid which
value is dictated by the Bernoulli equation and adjusts
to account for any viscous and mixing losses. The
pressure defect in the minimum area section of the device,
usually called the velocity head, varies with the mass
of the primary liquid flowing therein. ~ One or more
secondary liquids are introduced into the minimum area
section at prescribed stagnation pressures. The mass of
the secondary liquid flowing into the minimum area is
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dependent on its stagnation pressure, the pressuredefect
in the minimum area section due to the flowing primary
liquid, the secondary orifice area, the included angle
of these streams, and any drag eiement that is positioned
in the flow passage of the secondary liquid. If the mass
flow rate of the primary liquid is varied, the pressure
defect in the minimum area section varies, non-linearly,
and thus the mass flow of the secondary liquid varies.
By prescribing the stagnation pressure of the secondary
l li~uid, the secondary orifice area,the included angle of
these streams and the flow characteristics of the drag
element, the mass flow ratio of the two streams can be
varied in an arbitr2r~ manner as the mass flow in the
primary stream varies. By suitable selection of the
aforesaid parameters, the mass flow ratio of the secondary
to primary streams can be constant, or varying and linear,
or not constant and non-linear. One or more of the
secondary streams can be comprised of a powder such as
pulverized coal or a slurry of a powder and liquid.
In addition, the primary and secondary streams can be
interchanged such that a slurry flows in the primary
stream, and a liquid is injected as the secondary stream.
Finally, the stagnation pressure of the secondary liquid
can be less than the stagnation pressure of the primary
liquid and these streams can still be made to mix by a
suitable selection of the aforesaid parameters.
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If required, a third section may follow the j`
munimum section. The shape of the third section is aictated
by the needs of the mixing process. For example, if
pressure recovery is required, the third section can
!be a truncated cone, the smaller por,ion ma,ching the
Iminimum area section of the device and the aft portion, ¦ -
i downstream, made larger as dictated by the Bernoulli Law.
Similarly, if the purpose of the mixing of the liquids is
l so that they can react chemically, then the aft portion of
1 the third section may be of such shape as dictate~ by the }
! laws of aerothermochemistry.
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jBrief DescriPtion of the Drawlnas
¦ In the accompanying drawings:
Figure 1 is an exploded side elevational
sectional view of a two section metering-mixing device
in accordance with the present invention;
Figure 2 is a side elevational sectional
view of the metering-mixing device of Figure 1 followed
by a third section of increasing cross sectional area in
i accordance with an alternative embodiment of the present
¦ invention;
- ¦ Figure 3 is a schematic flow diagram of
the process of the present invention with means to vary
the stagnation pressures of the primary and secondary
1 liquids from external arbitrary-source signals;
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Figure 4a is a schematic flow diagram in
which the stagnation pressure of the secondary liguid is
varied according to the varying static pressure of the
primary fluid;
Figure 4b is a schematic flQw diagram in
which the stagnation pressure of the secondary liquid is
varied according to the static/stagnation pressure ~f
¦the primary fluid;
¦ Figure 5 is a schematlc flow diagram in
¦which the stagnation pressure of the primary liquid is
varied according to the static/stagnation pressure recovery
¦ after the metering-mixing aevice; i.e. feedback loop, and
¦in which the stagnation pressure of the secondary liquid
¦is varied according to the static/stagnation pressure
¦ of the primary liquid;
¦ Figure 6 is a schematic flow diagram in
¦ which the stagnation pressure of the primary liquid is
¦ varied from an external source and the pressure of the
, ¦ secondary liquid is varied as a function of both an
¦ arbitrary souce modified by the pressure in the primary
¦ liquid;
¦ Figure 7 is a schematic flow diagram
including a metering-mixing device together with an
¦ emulsifier that forms part of a fuel system for an engine
¦ and in which he stagnation pressure of the secondary
; ¦ liquid is ~aried by the pressure of the return fuel from
¦ the engine;
Figure 8 is a graph of the operating
characteristics of a meteFing-mixing module in which the
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stagnation pressure of the primary liquid remains constant,
and the stagnation pressure of the secondary liquid is
parametrically varied as the mass flow of the primary
liquid varies; and,
Fiyures 9 a, b and c depict the operating
loci for a metering-mixing module in which the operating
parameters are varied.
Detailed Description of the Preferred Embodiments
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l As stated, the present inven,ion relates to a
L0 1 process and app2ratus for metering and mixing two or more
liquids in any proportionate mass ratios. While the
following descriptions are directed toward the metering
and mixing of oil and alcohol, it should be understood
at the outset that the present invention can be applied
to any number of liquids in addition to those of the
described embodiments. It should be further understood
that the liquids of the mixture may be miscible or non- I
miscible, chemically reacting or non-reacting, and that
the ter~ "liquid" includes slurries, gels and thixiotropic
materials.
Reference is now made to Figure 1 wherein an
apparatus 10 is shown which is comprised of an elGngated
body member 12, a second body member 14, and a third
body memher 16. The body member 12 includes a convergent
passage 18 formed therein and defining a first section
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which is connected to a minimum area passage 20, also
formed in member 12. The passage 20 defines a second
section of apparatus 20 which is coaxial with the first
section. A transverse recess 22 extends through member
12 with the axis of recess 22 intersecting that of the
first and second sections. An aperture 24 at the b2se
of recess 22 connects recess 22 with passage 20 as shown.
Member 16 is provided with an external thread
which mates with a threaded bore 17 in member 14. An
L0 exterior thread 19 on member 14 permits that member ¦
¦ to be mounted to threads in recess 22.
~ile the member 12 may be generally cylindrical
to facilitate fabrication and assembly, other cross
l sectional configurations may be used where design
¦ considerations warrant the added expense in forming such
configurations. This is also true for the passages 18
and 20.
The aperture 24 may be positioned perpendicular
to the axis of passage 20 as shown, or its axis may be
¦ at an angle to the axis of passage 20, FuI',her, the
i axis of aperture 24 may be displaced from the axis of
passage 20, the position being determined by design
considerations and the laws of fluid dynamics, particularly
. the conservation of mass flow and Bernoulli's equation.
Body member 16 includes an ori~ice 26. As
noted, member 16 screws into a nozzle holder defined by
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body member 14. A bore through member 14 aligns with a
bore in member 16 that terminates in orifice 26. The
nozzle 16 and nozzle holder 14 together form a nozzle 15
which scre~s into the recess 22 in body 12 in the manner
described.
The operation o~ the metering-mixing apparatus
10 is set forth below. A first liquid, such as oil enters
member 12 at the entrance 30 and leaves through exit 32.
The pressure of the oil decreases as it flows in the
~L0 convergent section 18, the amount of pressure decrease
being dependent on the area ratios OI the entrance 30
- and mlnimum section 20, and the quantity of mass of oil
flowing. If the mass of oil flowing increases, the
pressure decrease at the minimum section 20 beco~es
greater. In particular, for constant area ratio of the
convergent section and constant stagnation pressure of
the primary liquid, the pressure at the minimum section ?.0
decreases as the oil mass flow increases. In this case,
there occurs a modulating primary mass flow with ccnstant
1 primary stangation pressure.
The secondary liquid flows into mixing apparatus
10 through the nozzle 16, which is located in its place
¦ in the recess 22. If the stagnation pressure of the
j - secondary liquid is equal to that of the primary liquid,
¦ then theoretically the mass ratio of the primary to
I secondary liquids is equal to the area ratio of the
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minimum section 20 to the orifice 26. As the primary
mass flow increases for constant stagnation pressure,
the static pressure in the minimum section decreases,
which causes the mass flow of the secondary liquid to
increase. Althouyh the pressure-mass flow relationship
is non-linear, in this case a linear metering ratio is ¦
! achieved, thus this metering ratio remains constant as
the mass flow of the primary liquid modulates.
l If the stagnation pressure of the primary
L0 ~ liquid remains constant as the primary mass flow modulates,
ll and the stagnation pressure of the secondary liquid is
!~ dlfferent from that of the primary liquid it is expected
¦ that the metering ratios will be non-linear. However,
l several synergistic effects were discovered with the
described construction which are particularly beneficial
in the application of-the apparatus to energy systems.
For the case where the stagnation pressure of the secondary
liquid is greater than that of the primary liquid, it
¦ is found that the liquid mass ratios of the secondary
¦ to primary streams increase as the primary liquid mass
; I flow decreases. In addition, the slope of mass ratio
changes with the secondary liquid stagnation pressure.
Conversely, for the case where the stagnation pressure
I of the secondary liquid is less than that of the primary
1 liquid, it is found that the secondary to primary streams
¦ mass ratio decreases as the primary liquid mass flow
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¦ decreases. In addi,ion, secondary stream mass flow
¦ shut off can be hydro~ynamically designed into the
¦ system by the appropriate selection of the aforesaid
¦ operating par2meters. It was further found that by
¦ placing a drag element in the nozzle orifice 26 which
¦ is sensitive to the stream velocity of the secondary
¦ liquid, flow regimes of linear followed by non-linear
behavior can be obtained for the case where the stagnation
¦ pressures of both streams are equal. Thus, for a fixed
¦ stagnation pressure of the primary liquid and with mass
¦ flow moaulation of the primary liquid, both linear and
¦ non-linear operating loci of liquid=liquid metering ratios
are obtained as the primary liquid modulates in mass flow.
~ These operating loci are discrete. In addition, by
l varying the stagnation pressure of the primary liquid,
¦ the whole field of liquid metering ratios is obtained
as the stagnation pressure and mass flow of the primary
¦ liquid modulates. In Figure 1, where the primary and
¦ secondary liquid streams are normal to each other, the
¦ degree of mixing between the liquids is enhanced by the
¦ primary liquid shearing the secondary liquid'as it passes
l by the nozzle orifice 26 in the minimum section 2C. The
¦ degree of mixing can be changed by changing the stream
velocities of the liquids or by changing the vaiue-of
the included angle between the streams (i.e., by ha~ing
the nozzle axis make some angle other than 90 with the
axis o~ body 12).
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However, by changing the included angle between
the streams, the relationship between the stagnation states
and flow properties vary, producing again diverse mixing
characteristics and concomiLant liquid-liquid metering
ratio operating loci as the mass of the primary stream
modulates.
With such a wide latitude in achieving these
metering-mixing ratios, the operating characteristics
of many modulating energy systems can be matched when
L0 various substances of different thermochemical properties
are substituted therein. The more co~mon of these energy
systems are boilers and engines in which mixtures of
alternate fuels are introduced into a primary fuel.
In Figure 2 a second embodiment of a metering-
mixing device 38 is shown. The device 38 is similar
to that shown in Figure 1, except that a divergen~ third
~assage 34 is added aft of passage 20 defining a third
section. In this case, the static pressure of the mixed
liquids increases as the flow velocity decreases and
exits at 36 the outlet of assage 34. In additiont
chemical reactions between the two liquids can be timed
to occur in the divergent section 34. The remainder of
device 38 is identical to that of device 10 and identical
reference numerals have been applied to like parts.
Figure 3 is a schematic flow diagram for
device 8 with means to vary the stagnation pressure of
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of the primary and seconday liquids~ Tne primary
liquid, such as oil, flows through a pipe 42, thence
through a pressure regulating valve 41, and into the
metering-mixing device 38, The secondary liquid, such
as alcohol, flows through a pipe 43, thence through a
reducing valve 40 and into the nozzle assembly 15 of the
metering-mixing device, 38. Independent control and
operation of the pressure regulating valves 40 and 41
is provided so that the stagnation pressures of the
primary and secondzry liqui2s can be varied arbritrarily,
In addition, means are provided to dynamically actuate
~he pressure resulating valves 40 and 41 by feeler lines
45 and ~6 obtained from arbitrary and external signal
sources. The pressure regulating valves can also be
dynamically operated electromechanically from electric
source signals as may be generated from mass flow 1-
transducers.
In a sucoessful practice of the present
invention, alcohol was metered and mixed with No.
Diesel Oil. The stagnation pressure of the primary
liquid; i.e. No. 2 Diesel Oil, was maintained constant,
A parametric experimental study was pursued in which
the stagnation pressure of the secondary liquid was
varied and the mass flow of the primary liquid was
modulated. The metering mixing device was six inches
long with entrance and exit cone angles of 60~ and 15
respectively and throat ~ore of 0.100 inch. The nozzle
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was a standard ~onarch nozzle, 30 gallons per hour with
60 cone angle~ The departing loci of the metering-mixture
curves are illustrated in ~Figure 8. The curves were transla-
ted upward and to the right as the stagnation pressure of
the secondary liquid was increased. Thus, for a fixed
primary stagnation pressure, a family of curves as shown
in Figure 8 results. By varying the primary liquid stagna-
tion pressure a group of families of curves superpose, one group
per primary liquid stagnation pressure. Several options
existfor metering-mixing operation: (a) fix both stagnation
pressures and obtain one operating locus, Figure 9a; (b)
fix the primary liquid stagnation pressure and vary the second-
ary liquid stagnation pressure and obtain a group of curves,
and the operating mixture ratio locus would thus intersect
the curves in the group, Figure 9b. In addition, it is
seen that it is possible to inject a secondary liquid into a
primary liquid, the former having the lesser stagnation
pressure; (c) fix the secondary liquid stagnation pressure
and vary the primary stagnation pressure, Figure 9c. In
this case, a behavior similar to case ~b) is observed; and
(d) vary the stagnation pressures of the primary and
secondary liquids from external independent source signals.
An arbitrary operating locus results depending on the primary
liquid mass flow schedule, and the individual stagnation
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pressure schedules for the various liquids.
Figures 4a and 4b are schematic flow diagrams
in which the stagnation pressure of the secondary liquid
is varied by a pressure regulating valve. Thus, in
Figure 4a, the secondary liquid (i.e., alcohol) flows
in pipe 43 into valve 51 in which the stagnation pressure
decreases, and thence to the nozzle assembly 15 of the
metering-mixing device 38. The regulating valve 51 may
contain a pressure loaded chamber, or a spring chamber
L0 that can be pressure loaded. The feeler line 52 is
attached to the primary liquid (i.e., oil) section 20 of the
metering-mixing module 38, so that it senses the oil
static pressure. Thus, the stagnation pressure and
mass flow of the secondary liquid varies as the static
pressure and mass flow the primary liquid.
In Figure 4b, a system similar to Figure 4a is
shown with the dlfference that the feeler line 52 is
attached so that it senses the stagnation pressure of
the primary liquid in the pipe 42. Thus, in the case
depicted in Figure 4a the operating locus can follow a
curve in the groups shown in Figure 9a and 9b, and in the
case depicted in Figure 4b the operating locus follows
essentially that shown in Figure 9a
In Figure 5, a schematic flow diagram of a
feedback loop control system is illustrated. In this
case the primary liquid flows in pipe 42 through the
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pressure regulating valve 41, through the metering-
mixing mod~le 38, and thence exits to an energy.or
alternate system downstream. A sensor 49 is placed at
the exit of the metering-mixing device which signal
modulates the flow of the primary liguid. The secondary
liquid flows in pipe-43 and is pressure modulated by
valve 51 which varies the mass flow through the nozzle
assembly 15. The modulation signal for the secondary
liquid is obtained downstream of ~he pressure regulating
valve 41 of the primary liquid. The operating locus
follows essentially that shown in Figure 9c.
In ~igure 6, a modification of the flow diagram
of Figure 5 is shown in which the stagnation pressure of
. the secondary liquid is modulated by an arbitrary external
sisnal in line 61 through the back pressure regulating
valve 62 and tempered by a signal in feeler line 60
obtained from the primary liquid.
In Figure 7 a schematic flow diagram of a ruel
system for an eng;ne or boiler.installation is shown.
Oil flows in line 42, through a fuel pump 70, through
the metering-mixing module 38,.thence through a liquid-
liguid emulsifier 72 such as that described in U.S. Patent
3,937,445 and into an.engine 74. Alcohol flows in pipe 43,
. through a pump 76, through a pressure regulating valve 40
and thence to the nozzle assembly lS of the metering-
mixing module 38. In this case the flow of alcohol is
modulated from a signal obtained in the fuel return loop 78
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from the engine, by means of the feeler line 52. A
check valve 79 is employed in the fuel return loop 78
to prevent backflow.
It is important to the present invention and
~ should be emphasized that although two liquids have
been discussed, the process and apparatus will operate
I with a multiplicity of liquids. ~nd as noted above,
the invention works equally well with slurries, gels
I and thixiotropic materials. The metering-mixing systems
¦ m2y be passive or active, each having particular app-
lications. ~inally, although one embodiment has been
sho~m, it should be appreciated that other passive or
active devices may be designed which can produce the
decrease in pressure and mass flow regimes.
` 15 Thus, in accordance with the above the afore-
-mentioned object are effectively attained.
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