Note: Descriptions are shown in the official language in which they were submitted.
CA 02280475 1999-09-02
IMPROVED SPRAY NOZZLE DESIGN
The present invention relates to an improved
design nozzles which produce an atomized spray.
This application is a division of co-pending
Canadian Patent Application Serial No. 2,090,865 filed
September 3, 1991.
In German Patent No. 2,627,880, there is described
a nozzle design for forming atomized sprays in which a
gas medium and a liquid medium are combined in a mixing
chamber and then expelled from the nozzle as atomized
liquid or as tiny gas bubbles, depending on the
relative proportions of the liquid and gas and whether
sprayed into a gaseous or liquid medium. The
atomization results from a considerable drop in
pressure as the two-phase mixture leaves the nozzle.
The nozzle is based on the principle that a properly-
formed two-phase mixture has an effective sonic
velocity that is only a fraction of the sonic velocity
of the two pure phases. For example, the speed of
sound for clean water under normal conditions is 1500
m/s and for clean air approximately 330 m/s. The speed
of sound of a defined two-phase mixture is
approximately 20 to 30 m/s. This nozzle design has
many attributes, including lower operating pressures,
lower pressure drop, reduced velocities, reduced air
consumption and reduced orifice abrasion.
However, the nozzle consists of a single orifice
which has many shortcomings. For example, if a large
duct is to be completely filled with fine liquid spray,
the 12° to 15° spray angle generated by the single
orifice may require placement of the nozzle many meters
back in the duct or the use of a multiple number of
individual nozzles to achieve the objective.
In the nozzle design described in the above-noted
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German Patent, the liquid feed is effected through the
same pipe as the spray is ejected from, while the gas
is fed from the side to a chamber which surrounds and
communicates with the liquid feed through a plurality
of openings in the liquid feed pipe just upstream of
the orifice, so as to form the two-phase mixture
therein. This feed arrangement often is unsuitable for
the feed lines available and the intended end use.
U.S. Patent No. 4,893,752, assigned to the
assignee hereof, describes a number of novel nozzle
designs intended to overcome the drawbacks of the
nozzle design of German Patent No. 2,627,880 by
providing a multiple number of orifices communicating
with a single source of both liquid and gas and
arranged to spray in different directions away from the
nozzle. These nozzle designs can be termed "cluster
nozzles".
The cluster nozzle designs of U.S. Patent No.
4,893,752 were developed to serve various applications
for the nozzles in terms of quantity of liquid to be
sprayed from a single nozzle, angle of spray pattern
required, density of spray within the spray pattern,
spray droplet size distribution desired, whether a
clean liquid or a slurry was to be sprayed, and where
the spray was to be introduced to the system.
More demanding requirements now are being required
to be met for the cluster nozzle designs. These
requirements generally relate to the quantity of liquid
to be sprayed from a single nozzle, the density and
angle of the spray pattern to be delivered and the
droplet size distribution to be generated.
An increase in the amount of liquid to be sprayed
can be met generally by an increase in size of the
orifices in the nozzle or by adding more orifices of
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the same size. While single orifice nozzles may range
up to 35 mm in size (I. D. of the orifice), the standard
nine orifice cluster nozzles (designed as seen in
Figures 3 and 4 of U.S. Patent No. 4,893,752) with
orifices larger than 8 or 9 mm do not perform as well
as a similar nozzle with 8 mm or smaller orifices.
This observation, in effect, has placed a limitation on
the quantity of liquid that can be effectively sprayed
from a single nozzle. The main deficiency observed,
say for a nine orifice nozzle where the orifices were
10 mm, was a very non-uniform distribution of liquid
emanating from each of the orifices.
It is also observed that, as more orifices are
used in the cluster nozzles of U.S. Patent No.
4,893,752, the orifices must be smaller yet if uniform
spray patterns are to be obtained. Thus, a 16 X 6 mm
cluster nozzle was designed for a particular
application but did not produce the degree of spray
uniformity desired. A nozzle with 16 X 6 mm orifices
installed in three concentric rings about the axis of
the nozzle was built with each orifice preceded by a
chamber where the liquid was introduced at the end
opposite the orifice, via a separate liquid chamber,
into a mixing section where the atomizing gas was
introduced radially into the liquid flow through a
plurality of orifices which were fed gas from the
chamber communicating with a source of gas. The gas
and liquid form a two-phase mixture within the mixing
chambers which is subsequently ejected through the
orifice whereupon a spray is produced. In this case,
we were able to produce a wider spray angle while
significantly increasing the density of spray droplets
within the spray pattern. However, we were still able
to detect some degree of variability emanating from the
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orifices.
In U.S. Patent No. 4,893,752, there is also
disclosed a two-phase nozzle wherein a single mixing
chamber is employed wherein the liquid and gas streams
are joined to form a two-phase mixture, the mixture
then being directed to an array of orifices located as
desired at the delivery end of the nozzle (see Figures
5 and 6 of the U.S. Patent. This structure is claimed
in U.S. Patent No. 5,025,989 divided out of U.S. Patent
No. 4,893,752). Within certain constraints, this
embodiment of the cluster nozzle has been found to
produce excellent sprays which are comparable to the
sprays delivered from nozzles where a separate mixing
chamber preceded each individual orifice (as in Figures
3 and 4 of U.S. Patent No. 4,893,752). However, the
constraints experienced were similar to those found for
the standard cluster nozzle, i.e. one with individual
gas-liquid mixing chambers for each orifice, namely,
less than perfect sprays emanating from each orifice as
their size and the amount of liquor being sprayed
increased.
We have now surprisingly found that there can be
achieved a significantly-improved performance of multi-
orifice nozzles of the type wherein individual gas-
liquid mixing chambers are provided for each orifice.
This improved performance is achieved by introducing
gas into the liquid chamber prior to distribution of
liquid to the individual mixing chambers, to effect a
pre-mixing of gas and liquid. Gas is introduced to the
liquid in two stages, first in the liquid chamber and
then in the individual gas-liquid mixing chambers.
This seemingly simple structural modification to
the cluster nozzle design produces an exceptionally
uniform spray from each orifice. As a result, it is
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possible to increase significantly the amount of liquid
to be sprayed from the cluster nozzle, either by
increasing the size or number of individual orifices,
without impairing the quality of the spray.
Accordingly, in one aspect of the present
invention and as claimed in parent Application Serial
No. 2,090,865, there is provided a nozzle for the
formation of an atomized spray of fine liquid droplets
in a continuous gaseous phase or of fine gas bubbles in
a continuous liquid phase, which comprises first
chamber means for communicating with a source of
liquid, second chamber means for communicating with a
source of gas, and passage means extending between the
second chamber means and the first chamber means for
pre-mixing said gas and liquid in said first chamber
means to form a first mixture of gas and liquid. A
plurality of individual mixing chamber means
communicate with both the first and second chamber
means for mixing the gas from said second chamber means
and the first gas-liquid mixture from the first chamber
means to form an equilibrium two-phase mixture of gas
and liquid in each of the individual mixing chamber
means for ejection from the nozzle. A plurality of
orifice means is located downstream of and communicates
with the plurality of individual mixing chamber means
for ejection of the two-phase mixture from each of the
individual mixing chamber means to form the atomized
spray.
The present invention also includes, in another
aspect as claimed in parent Application Serial No. 2,
090, 865, a method of forming an atomized spray of fine
liquid droplets in a continuous gaseous phase or of
fine gas bubbles in a continuous liquid phase by a
plurality of steps. A liquid and a gas are fed to a
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CJ
first gas-liquid mixing zone and a first mixture of gas
and liquid i.s forrrGed in the fir4>':, c~as-liquid mixing zone.
The first gas-liquid mixture and a gas are fed to a
plurality of indiViduaL second gas-liquid mixing zones
.'~ and an equilibrium two-phase mixture of gas and liquid is
formed in each of the individual second gas-liquid mixing
zones. The two-phase mixture is ejected. from each of the
individual second gas-liquid mixing zones through
orifices to form the atomized spray.
In addition to t:.he ability to increase the amount of
liquid to be sprayed from the nazzle by the staged mixing
of gas with liquic., anci quite uraexpec:tedly, the addition
of gas, usually compressed air, to the :Liquid chamber as
well as to individual mixing chambers associated with
each orifice had no signit'icar~t= effect on the total
amount of gas consumed per nozzle. Therefore, it has
been concluded tha ~ the manner c>f i.ntrod.uction of the gas
to the liquid chancier is not c~ri.tical. The present
invention also provides a three-stage introduction of gas
to the liquid as ar:c acadit.ional embodiment of the
atomizing nozzles to ensure the formation of an
equilibrium two-phase mixture especially when larger
volumes of liquid are to be sprayed from a single multi-
orifice nozzle.
Accordingly, she present ir~Vention provides a nozzle
of cylindrical shape for the formation o.f an atomized
spray of fine liquid lroplets in a continuous gaseous
phase or of fine gas bubbles ire a continuous _iquid
phase, which comprises: firs; chamber means comprising a
single cylindrical chamber :means axially extending within
the nozzle from an in~_et end for communicating with a
source of liquid to an cutlet end, second chamber means
comprising a single annular chambei_° means axially
CA 02280475 2002-09-03
extending within the nozzle ~~oncentric:ally with the
single cylindrical chamber means and having an opening in
an exterior side wall thereof ivor communicating with a
source of gas, third ~.hamber means separated from the
second chamber mean's by annular internal wall means, a
plurality of axially-direc:teci passage: through the
internal wall means extending between the second and
third chamber means for_ E:iow of gas from the second
chamber means to the tr.ird chamber means, a plurality of
individual mixing ;:hamber means communicating with the
outlet end of the first charr~ber means for receiving
liquid therefrom and the th_Lrc~ chamber means for
receiving gas therefrom and for rn.ixing the gas and liquid
to form a two-phase mixture of the gas and liquid in each
of the individual mixing chamber means for ejection from
the nozzle, and a plurality of orifice mean downstream of
and communicating wi°vh the pl_uralit~y of individual mixing
chamber means f=or ejection o:f t:tue two-phase mixture from
each the individual mixing chamber me.ar~s to form the
atomized spray.
In this si~ructure, passage means preferably extends
between the second chamber means and i:he first chamber
means comprising at least one opening formed through a
common external wall of the first c:ham~>er means and
internal wall of the second chamber means for pre-mixing
the gas and liquid in ~;he first. chamber means to form a
first two-phase mixture of gas and liquid.
The plurality of' individual mixing chamber means is
preferably pro~JidE_~~ by individual pipes extending from
3c~ the outlet end of the first charnbe~r means to the
plurality of orifice means an<~ hav:inq a plurality of
openings formed through the wall of each of the
CA 02280475 2002-09-03
individual pipes conununicating with the third chamber
means.
Each of th.e orifice means preferably i;s circular and
is of the same diameter as and communicates directly with
the plurality of individual pipes.
While the appliw~ants do not: wi;~h to be bound by any
theory to explain 1=he results obtained by the nozzle
design provided tzerein, it is tn.ought that the
effectiveness of the design relates to the kinetics of
the formation of two-phases gas/l.iquid mixtures. Where
relatively large flows of liquid must fo m a suitable
two-phase mixture w:iile flowing through the confines of a
relatively small diameter pipe, it is probable that the
retention time in the mixing chamber needs to be
increased.
This theory also suggests other approaches
additional to that adopted here, ruamely increasing the
length of the gas-liquid mixing charcrber or increasing the
diameter of th.e mixing chamber, thereby providing more
time to achieve the correc::t degree of two-phase
formation. However, both approaches require an increased
nozzle size, in terms of diameter and/or length,
increasing the cost: and complexity of producing the
nozzle.
2.5 In contrast, the modification provided herein has no
effect on nozzle L;i.ze and very 1i_ttle effect on the cost
of the nozzle and 'hence is highly to be preferred.
The invention is described furt:her, by way of
illustration, with reference t~~ the accompanying
drawings, wherein:
CA 02280475 1999-09-02
Figure 1 is a plan view of a nozzle accordance
with one embodiment of the invention and as claimed in
parent Application Serial No. 2,090,865;
Figure 2 is a sectional view taken on line 2-2 of
Figure 1;
Figure 3 contains sectional (Figure 3A) and front
elevational (Figure 3B) views of a 360° spray nozzle
provided in accordance with another embodiment of the
invention and as claimed in parent Application Serial
No. 2,090,865;
Figure 4 contains sectional (Figure 4A) and front
elevational (Figure 4B) views of a sixteen-orifice
nozzle constructed in accordance with a further
embodiment of the invention and as claimed in parent
Application Serial No. 2,090,865;
Figure 5 contains sectional (Figure 5A) and front
elevational (Figure SB) views of a fifty-eight orifice
nozzle constructed in accordance with an additional
embodiment of the invention and as claimed in parent
Application Serial No. 2,090,865;
Figure 6 contains sectional (Figure 6A0 and front
elevational (Figure 6B) views of a nozzle having
tertiary-stage air introduction and constructed in
accordance with an embodiment of the invention as
claimed herein; and
Figure 7 contains sectional (Figure 7A) and front
elevational (Figure 7B) views of a nozzle having an
alternative form of tertiary air introduction to that
shown in Figure 6.
Referring first to Figures 1 and 2 of the
drawings, there is illustrated therein one embodiment
of multiple orifice cylindrical nozzle 110. As may be
seen, the nozzle 110 has two circularly-arranged sets
of orifices 112 and 114. The inner set of orifices 112
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is formed in a first tapered external surface 116 of
the nozzle 110 arranged at an angle a to a line drawn
perpendicularly to the axis of the nozzle 110. The
outer set of orifices 114 is formed in a second tapered
external surface 118 of the nozzle 110 arrange an angle
~3, greater than angle a, to a line drawn perpendicular
to the axis of the nozzle 110. By providing two sets of
orifices arranged at different angles, the total spray
angle generated by the nozzle 110 can be varied widely
while at the same time effectively eliminating spray
pattern interference.
The angle a generally is small so that the
orifices 112 fill the centre of the total spray being
generated. The angle (3 is designed to provide the
overall spray angle desired, which may vary with nozzle
110 for about 30° to about 180°.
If a larger, more dense spray is required, a
further set of orifices may be provided, say from 9 to
12 in number, arranged in the circular array on a
tapered surface with a taper angle greater than angle
(3. The extent to which additional sets of orifices may
be added to the nozzle 110 on tapered surfaces having
increasing angles of taper was previously limited by
the ability to provide proper (equilibrium) two-phase
mixtures for larger flow rates or nozzle (orifice)
sizes.
The nozzle 110 has an interior axial chamber 18
which is intended to be connected to a liquid flow line
through liquid inlet 19 in the bottom wall of nozzle
110. Each of the orifices 112, 114 is connected to the
chamber 18 by an individual pipe 20 to permit flow of
liquid from the chamber 18 to the respective orifices
112 and 114.
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An air or other gas inlet 22 is provided in the
side wall 24 in communication with a second internal
chamber 26 which is separated from the axial chamber 18
by an internal wall 28, which is a body part threadedly
engaged or otherwise joined to the outer wall 24 of the
nozzle 110. The chamber 26 communicates with the
interior of the pipes 22 through a plurality of
openings 30 extending through the wall of each of the
pipes 20. For this reason, the pipes 20 also may be
considered as air or gas distributors.
In operation, the liquid passing through the pipes
from the chamber 18 mixes with gas passing from the
chamber 26 through the openings 30 to form a two-phase
mixture in the pipe 20, which thereby functions as a
15 mixing chamber for gas and liquid. As the mixture
exits the nozzle 10 through the orifices 112, 114, the
sudden change in pressure causes atomization to form
fine liquid droplets in a continuous gaseous phase or
fine gas bubbles in a continuous liquid phase,
20 depending on the relative proportions of gas and liquid
in the two-phase mixture. In most applications,
proportions of gas and liquid are provided which
produce a discontinuous phase of liquid droplets.
Further particulars of the atomization procedure are
described in German Patent No. 2,627,880
A passage 120, or a plurality of such passages, is
provided joining the air entry port 22 to the liquid
chamber 18 to permit air fed to the gas entry port 22
to pass to the liquid chamber 18 to effect a pre-mixing
of gas and liquid, prior to passage of the premixture
of gas and liquid to the pipes 20, wherein further
mixing of gas and liquid occurs to form an equilibrium
two-phase gas-liquid mixture to be sprayed from the
orifices 112, 114. The presence of this passage 120
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provides an improvement in spray quality obtained from
the nozzle, particularly when larger amounts of liquid
are required to be sprayed from the nozzle, as is the
case when the number and/or size of the individual
orifices 112, 114 is increased.
For larger nozzles or those spraying larger
volumes of liquid, the passage 120 may be supplemented
by one or more additional passages communicating
between the liquid chamber 18 and the gas chamber 26 to
provide the desired degree of pre-mixing of gas and
liquid.
The design illustrated in Figures 1 and 2 permits
the multiple-orifice nozzle design to contain an
indefinite number of orifices through the addition of
third and even fourth rings of orifices without the
short-comings discussed above, to provide wider spray
angles and higher density and more uniform spray
patterns. With suitable orifice distribution, the
modified nozzle design may produce fan-shaped spray
patterns with a high degree of uniformity of spray.
Turning now to Figure 3, there is illustrated
therein a 360° spray nozzle 200 in which all of the
orifices are placed normal to the axis of the nozzle or
duct.
The nozzle 200 has a plurality of equally-
arcuately spaced orifices 202 arranged normal to the
axis of the nozzle. The nozzle 200 has an interior
axial chamber 204 which is intended to be connected to
a liquid flow line through a liquid inlet 206. Each of
the orifices 202 is connected to the chamber 204 by an
individual pipe 208 to permit flow of liquid from the
chamber 204 to the respective orifices 202.
An air or other gas inlet 210 is provided in the
side wall 212 in communication with a second internal
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chamber 214 which is separated from the axial chamber
204 by an internal wall 216.
The chamber 214 communicates with the interior of
pipes 208 through a plurality of openings 218 through
the wall of each of the pipes 208. In accordance with
the invention, a plurality of passages 220 is provided
joining the air chamber 214 to the liquid chamber 204
to permit air fed to the gas entry port 210 to pass to
the liquid chamber 204 as well as to the interior of
the pipes 208.
The nozzle 200 operates in analogous manner to the
nozzle 110 described above with respect to Figures 1
and 2 and reference may be had to that description.
Accordingly, gas and liquid are premixed in the chamber
204 and the premixture passes to the plurality of
individual pipes 202, wherein further mixing with gas
occurs to form an equilibrium two-phase mixture under
the conditions of flow and pressure before ejection of
the atomized spray from the plurality of individual
orifices 202.
The configuration shown in Figure 3 makes possible
improved gas quenching, for example, at the inlet of a
scrubber for solute gases and/or particulates in a gas
stream where very hot gases, e.g. 2000°F, are
encountered. The spray nozzle 200 can be placed very
close to the gas entry point without spraying water
onto brick/ceramic lining of a duct carrying the hot
gas stream to the scrubber.
In Figure 4, there is illustrated a further
embodiment of nozzle similar to that illustrated in
Figures 1 and 2 but in this case there are a
significantly increased number of nozzle orifices,
which is made possible by providing premixing of some
of the gas with the liquid.
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As seen therein, a nozzle 300 has two circularly-
arranged sets of orifices 302, 304 with the individual
orifices in each set being equally arcuately spaced.
This nozzle 300 also is illustrated possessing an axial
orifice 306, but this orifice may be omitted, if
desired. The spray formed by the axial orifice 306
tends to draw in adjacent sprays, thereby decreasing
the total spray angle produced by the nozzle. While
this effect may represent a problem with small numbers
of orifices, as described in the aforementioned U.S.
Patent No. 4,893,752, the effect may be used
beneficially where larger numbers of orifices are
employed, as the improvements of the present invention
permit, to achieve a higher spray density.
The inner set of five orifices 302 is formed in an
external surface 308 which is arranged at a first angle
to the axis of the nozzle while the outer set of ten
orifices 304 is formed in an external surface 310 which
is arranged at a steeper angle, in analogous manner to
surfaces 116 and 118 in the embodiment of Figures 1 and
2.
The nozzle 300 has an interior axial chamber 312
which is intended to be connected to a liquid flow line
through inlet 314. An air or. other gas inlet 316 is
provided in the side wall 318 of the nozzle 300 in
communication with a second internal chamber 320 which
is separated from the axial chamber 312 by an internal
wall 322.
A plurality of openings 324 is provided through
the internal wall 322 to permit air to pass from the
second internal chamber 320 to the axial chamber 312 to
form a first mixture of gas and liquid in the axial
chamber 312.
Each of the orifices 302, 304, 306 is connected to
14
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the downstream end of the axial chamber 312 by a
individual pipe 326 to permit flow of the first gas-
liquid mixture from the axial chamber 312 through the
individual pipes 326 to the various orifices 302,
304,306.
A plurality of openings 328 is provided through
the wall of each of the individual pipes 326 so as to
effect communication between an air chamber 330 and the
internal region of each of the individual pipes 328.
This arrangement permits air in the chamber 330 to pass
into the individual pipes 326, so as to form with the
first gas-liquid mixture received from the axial
chamber 312 an equilibrium two-phase mixture in each of
the individual pipes 328 for ejection from the orifices
302, 304, 306.
The air chamber 330 communicates with the second
internal chamber 320 by a plurality of axially-directed
passages 332 through a dividing wall 334 to permit air
fed through inlet 316 to the second internal chamber
320 to pass to the air chamber 330. This arrangement,
whereby the chambers 320 and 330 are communicated by a
ring of axially-directed passages 332 through the
dividing wall 334, improves distribution and flow of
compressed air within the nozzle structure 300, in
comparison to the arrangement illustrated in Figures 1
and 2, resulting in improved air balance within the
nozzle. In addition, decreased air turbulence in the
air chamber 330 results, thereby improving delivery of
compressed air to the individual pipes 326 and
decreasing energy loss from the improved fluid
dynamics.
This arrangement for air distribution within the
nozzle also may be employed with the multiple air
distribution nozzle structure of U.S. Patent
CA 02280475 1999-09-02
No.4,893,752.
Figure 5 shows the application of the principles
of the invention to greater numbers of orifices, in
this case numbering 58, provided in five circular
groupings arranged at a different angle to the nozzle
axis. Within each grouping, the orifices are equally
arcuately spaced. Reference numerals common to those
employed for Figure 4 are employed therein to describe
the same elements. As in the case of Figure 4, the
axially-directed orifice 306 may be omitted.
In the embodiment of Figure 5, the various
orifices are illustrated as being formed in a domed
head 336 to provide the different angles of projection
of sprays from the nozzle for simplicity of
illustration. However, the various groups of orifices
usually are provided on flat surfaces provided at
increasingly steeper angles for the respective groups
of orifices.
The orifices in Figure 5 are arranged in a first
group 302 of three orifices, a second group 304 of six
orifices, a third group 338 of twelve orifices, a
fourth group 340 of twelve orifices and a fifth group
342 of twenty-four orifices. With the optional axial
orifice 306, the total number of orifices illustrated
is 58 while with the optional axial orifice 306
omitted, the total number of orifices becomes 57.
In the various illustrated embodiments, the
orifices are shown as all having the same diameter,
since this arrangement promotes a uniform droplet size
distribution. However, in some instances, it may be
desirable to produce a specific combination of larger
and smaller liquid droplets from a cluster nozzle.
For example, in gas scrubbing, it is often
desirable to introduce the spray counter-current to the
16
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gas flow to improve residence time as well as effect a
more uniform distribution of the spray in the duct.
However, when a fine spray is introduced within a duct
and counter-current to the flow of gas, the spray often
expands to such an extent that fifty to seventy percent
of the liquid is deflected enough to impinge on the
duct wall, where the droplets agglomerate and then
coalesce to collect in the lower portion of the duct.
To alleviate this situation, it may be desirable to
spray somewhat larger droplets from those orifices
located farthest from the axis of the nozzle and finer
droplets from those orifices located closest to the
axis of the nozzle.
Such an effect can be achieved by providing
orifices of corresponding larger or smaller diameter,
with the outer orifices being of larger diameter than
the inner orifices. A reversal of this arrangement may
be employed, if desired. A larger flow of liquid is
sprayed per orifice where the larger diameter is
employed. Any inequality and lack of uniformity of
flow that results can be compensated for by suitable
adjustment of the number of orifices used on each
level.
Further, the orifices in the various groupings
generally are equally arcuately spaced from each other
in order to obtain a uniform distribution of the sprays
emanating from the orifices. However, for particular
applications, it may be desired to provide a degree of
lack of such uniformity by differently spacing the
orifices.
Turning now to Figures 6 and 7, these Figures
illustrate two nozzles 400 according to embodiments of
the invention wherein further premixing of liquid and
gas is effected. The structure illustrated is a
17
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modified form of the structure illustrated in Figure 4
and common reference numerals are employed to describe
common elements.
In Figure 6, a pipe 402 extends transversely of
the axial chamber 312 between opposite portions of the
wall 322 thereof so as to communicate with the second
internal chamber 320 and thereby provide a flow of
compressed air to the interior of the pipe 402. The
pipe 402 is provided with openings 404 through the wall
thereof to permit compressed air to pass from the pipe
402 to the liquid flowing in the chamber 312, thereby
effecting a further pre-mixing of gas and air within
the nozzle 400.
In the embodiment of Figure 7, a separate gas feed
pipe 406 is provided, which reeds gas into the liquid
feed pipe 408 before the liquid is introduced to the
nozzle 400.
In summary of this disclosure, the present
invention provides a novel cluster nozzle design which
provides for improved uniformity of spray pattern and
which enables a greater liquid output to be attained
through the use of larger size and numbers of orifices,
while retaining very uniform sprays. Modifications are
possible within the scope
of this invention.
18
