Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to an atomizing nozzle
assembly.
It has already been proposed in United States
Patent No. 4,592,506, dated June 3, 1986, "Wear Resistant
Nozzle Assembly", C.E. Capes, A.J. Bennett, K.A. Jonasson
and W.L. Thayer, to provide a wear resistant nozzle assem-
bly having an outwardly diverging frustum of a cone shaped
deflector core of wear resistant ceramic and a nozzle rim
of wear resistant ceramic and having an outwardly flared
inner surface encircling the core to form a flared,
atomizing nozzle orifice therewith. The core is mounted in
a flared socket of a deflector core holder and inner and
outer sleeves feed, say, atomizing air to the deflector
core surface and, say, a coal liquid mixture fuel inwardly
around the nozzle rim so that the fuel is held by the air
as a film against the nozzle rim inner surface and then
atomized as it emerges from the nozzle rim
It has already been proposed by the applicants in
the Proceedings of the Fifth International Workshop on Coal
Liquids Fuels Technology, pages 364 to 378, held at
Halifax, Nova Scotia, Canada, October, 1985, to provide a
burner assembly for coal liquid mixtures wherein the geome-
try of an abruptly terminating mixing zone is adjusted by
means of a screw threaded engagement at the upstream end of
coaxial tubes which deliver the atomizing air and fuel to
the nozzle at the downstream ends of these tubes.
While the burner assemblies disclosed in United
States Patent No. 4,592,506 and at the above mentioned
workshop are useful, there is a need for an atomizing
nozzle assembly wherein an adjus-ting mechanism mounts the
deflector core to the nozzle rim in close proximity to the
mixing zone, and means are provided for accommodating
differential thermal expansions between members attached
to, and for delivering fluids to the mixing zone between,
the deflector core and nozzle rim, and extending rearwardly
from the adjustment mechanism, in order that the effects of
these differential expansions on the nozzle setting are
negligible giving substantially constant atomization, and
damage ~o the ceramic nozzle parts due to these differen-
tial thermal expansions is avoided.
According to the present invention there is
provided an atomizing nozzle assembly comprising:
a) a frustum of a cone shaped, deflector core of a
wear resistant ceramic material, said deflector having an
outwardly divergi.ng surface leading to a chamfered extrem-
ity, in a downstream direction for liquid-to-be-atomized,
an outer portion of the diverging surface of the deflector
core forming an outwardly deflecting surface for, in opera-
tion, an atomizing fluid jet to flow in an unobstructed
manner along the whole length thereof,
b) a nozzle rim of a wear resistant ceramic mate-
rial, the rim having a wedge-shaped inward p.otrusion with
a downstream side of the wedge shape protrusion having an
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outwardly flared, inner surface which is substantially
parallel to, and co-extensive with, a downstream por~ion of
the outwardly diverging surface of the deflector core to
form therewith a mixing zone leading to an atomizing nozzle
orifice outlet SQ that, in operation, liquid-to-be-atomized
will be held against the surfaces bounding the mixing zone,
until it is substantially completely mixed, and atomized as
it emerges from the orifice outlet,
c) a deflector core holder having a screw threaded
upstream end and a flared socket portion at a downstream
end, the flared socket portion having an outer, cylindri-
cally shaped extremity, the flared socket having an
upstream portion of the deflector core closely fitting and
aligned therein, the flared socket portion, in operation~
providing a smooth outer surface for guiding atomizing
fluid towards and along the outwardly deflecting surface of
the outer portion of the deflector core protruding from the
flared socket portion,
d) securing means securing the deflector core in
0 the flared socket portion,
e) an inner, cylindrical sleeve having a screw
threaded, inner, upstream end portion in threaded engage-
ment in an adjustable manner, with the screw threaded,
upstream end portion of the deflector core holder and
having a downstream end portion with an enlarged bore and
terminating at a downstream end having inner and outer
chamfers, the downstream end portion being around the
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flared socket pol-tion to form a fluid passage around the
cylindrically shaped extremity of the deflector core holder
having a substantially constant cross-sectional area for,
in operation, passing a substantially constant stream of
atomizing fluid therealong to an atomizing fluid orifice
formed between the inner chamfer and the outer deflecting
surface of the flared socket so that, in operation, a jet
of the atomiæing fluid will issue from the atomizing fluid
orifice and be directed along the outer portion of the
outwardly deflecting surface of the deflector core,
f) an upstream collar forming a mounting means on
the front end of the inner cylindrical sleeve,
g) an outer,.cylindrical sleeve sealed and secured
against relative movement by the upstream collar on the
front end of the inner sleeve and having a stepped, annular
recessed portion at the downstream end with the nozzle rim
mounted therein and protruding radially inwardly therefrom,
a portion of the outer sleeve having a relatively larger
bore diameter than the outside diameter of the inner sleeve
and forming therearound an unobstructed, liquid passage
having a cross-sectional area for, in operation, conveying
liquid-to-be-atomized at a predetermined mass flow rate
towards the upstream side of, and inwardly around, the
wedge-shaped protrusion of the nozzle rim,
h) means securing the nozzle rim in the stepped,
annular recessed portion,
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i) an adjustment means connected to the deflector
core holder for adjusting the screw threaded engagement
between the deflector core holder and the inner cylindrical
slee~e to thereby adjust the width (W) of the mixing zone,
j) means for delivering atomizing fluid to the
fluid passage,
k) means for delivering liquid-to-be-atomized to
the liquid-to-be-atomized passage,.and
l) a differential thermal expansion accommodating
gland slidably mounting an intermediate portion of the
inner, cylindrical sleeve in a rear end portion of the
outer, cylindrical sleeve.
In some embodiments of the present invention the
adjustment means is capable of adjusting the width of the
mixing zone to an L to W range ratio which is within the
range of about 5:l to about lO:l, preferably 7:l to 8:l,
where L is the length of the mixing zone in the direction
of flow therethrough and W is the width of the mixing zone.
In other embodiments of the present invention the
face forming the chamfered extremity of the deflector core,
and a downstream side face of the nozzle rim, are symmetri-
cally inclined, at any circumferential position, with
respect to a centerline extending along the mixing zone at
that circumferential position, at an included angle (ao) in
the ratio with respect to the angle (a), at which the
atomizing fluid is directed towards the outwardly diverging
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surface of the deflector core of about 130 : 50 to about
100 : 80.
The adjustment means may comprise a shaft for
rotating the deflector core and extending rearwardly there-
S from along the inner cylindrical sleeve, a gland slidablymounting a rear end portion of the shaft, which extends
therethrough, in the inner cylindrical sleeve, means for
rotating the rear end of the shaft.
A heat exchange casing may be provided around the
outer cylindrical s].eeve and mounted therearound at a front
end by the said mounting means, and a differential thermal
expansion accommodating gland slidably mounting a rear end
portion of the heat exchange casing on the outer cylin-
drical sleeve.
In the accompanying drawings which illustrate, by
way of example, an embodiment of the present invention,
Figure l is a sectional side view of an atomizing
nozzle, and
Figure 2 is an enlarged sectional side view of the
nozzle components of the nozzle assembly shown in Figure 1.
Referring now to Figures 1 and 2 there is shown an
atomizing nozzle assembly comprising:
a) a frustum of a cone shaped, deflector core l of
a wear resistant ceramic material, said deflector having an
outwardly diverging surface 2 leading to a chamfered
extremity 4, in a downstream direction for liquid-to-be-
atomized, an outer portion 5 of the diverging surface of
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the deflector core, an outwardly deflecting surface 6 for,
in operation, an atomizing fluid jet to flow in an
unobstructed manner along the whole length thereof,
b) a nozzle rim 8 of a wear resistant ceramic
S material, the rim having a wedge-shaped inward protrusion
10 with a downstream side 12 of the wedge shape protrusion
10 having an outwardly flared, inner surface 14 which is
substantially parallel to, and co-extensive with, a down-
stream portion of the outwardly diverging surface 2 of the
1~ deflector core 1 to form therewith a mixing zone 16 leading
to an atomizing nozzle orifice outlet 18 so that, in opera-
tion, liquid-to-be-atomized will be held against the
surfaces 2 and 14 bounding the mixing zone 16, until it is
substantially completely mixed, and then atomized as it
emerges from the orifice outlet 18,
c) a deflector core holder 20 having a screw
threaded upstream end portion 22 and a flared socket
portion 24 at a downstream end, the flared socket portion
24 having an outer, cylindrically shaped extremity 26, the
flared socket portion 24 having an upstream portion 28 of
the deflector core 1 closely fitting and aligned therein,
the flared socket portion 24, in operation, providing a
smooth outer surface 24 for guiding atomizing fluid towards
and along the outwardly deflecting surface 6 of the outer
portion 5 of the deflector core 1 protruding from the
flared socket portion 24,
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d) securirlg mean~ in the form of a cap 32 and bolt
34 securing the deflector core 1 in the flared socket
portion 24,
e) an inner, cylindrical sleeve 36 having a screw
threaded, inner, upstream end portion 38 in threaded
engagement in an adjustable manner, with the screw
threaded, upstream end portion 22 of the deflector core
holder 20 and having a downstream end portion 40 with an
enlarged bore and terminating at a downstream end having
inner and outer chamfers 42 and 44 respectively, the down-
stream end portion 46 being around the flared socket
portion 24 to form a fluid passage 46 around the cylindri-
cally shaped extremity 26 of the deflector core holder 20
for, in operation, passing a substantially constant stream
of atomizing air therealong to an atomizing fluid orifice
formed between the inner chamfer 42 and the outer deflect-
ing surface 6 of the flared socket so that, in operation, a
jet of the atomizing.fluid will issue from the atomizing
fluid orifice and be directed along the outer portion 5 of
the outwardly deflecting surface of the deflector core 1,
f) an upstream collar so forming a mounting means
on the front end of the inner, cylindrical sleeve 36,
g) an outer, cylindrical sleeve 48.sealed on, and
secured against relative movement by the upstream collar 50
on the front end of the inner sleeve 36 and having a
stepped, annular recessed portion 52 at the downstream end
with the nozzle rim 8 mounted therein and protruding radi-
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ally inwardly therefrom, a portion 54 of the outer sleeve48 having a relatively larger bore diameter than the
outside diameter of the inner sleeve 36 and forming there-
around an unobstructed, liquid passage 56 for, in opera-
S tion, conveying liquid-to-be-atomized towards the upstream
side of, and inwardly around, the wedge-shaped protrusion
10 of the nozzle rim 8,
h) means, in the form of a threaded collar 58,
securing the nozzle rim 8 in the stepped, annular recessed
portion 52,
i) an adjustment means, in the form of shaft 64
and barrel 66 (Figure 1~, connected to the deflector core
holder 20 for adjusting the screw threaded engagement
between the deflector core holder 20 and the inner cylin-
drical sleeve 36 to thereby adjust the width (W) of themixing zone,
j) means, in the form of a tube 68, forming in
this embodiment an intermediate portion of the cylindrical
sleeve 36, and ports such as port 70, for delivering
atomi7.ing fluid to the fluid passage 46,
k) means, in the form of tube 72/ forming in this
embodiment a rear end portion of the outer, cylindrical
sleeve 48, and ports such as port 74 in the collar 50, for
delivering liquid-to-be-atomized to the liquid-to-be-
atomized passage, andl) a differential thermal expansion accommodating
gland 106 slidably mounting the intermediate portion 68 of
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the inner, cylindrical sleeve 36 in the rear end portion 72
of the outer, cylindrical sleeve 48.
The deflector core 1 has a bore 76 in which a
spigot 78 of the cap 32 is located, and the head of the
S bolt 34 is countersunk in the cap 32 to be flush therewith.
The nozzle rim 8 is located in a retaining ring 80
which is welded in a locating sleeve 82. The locating
sleeve 82, whose inner surface 84 forms a part of the
boundary of the liquid passage 56, is secured in the
stepped, annular recessed portion 52 by the threaded collar
58.
The deflector core holder 20 has a recess 86 in
which the shaft 64 is secured by means of a pin 88.
The collar 50 of the inner sleeve 36 is located in
a recess 90 in the outer sleeve 48 and has annular rings 92
and 94 locating the tubes 68 and 72 respectively which are
welded in position.
The outer sleeve 48 has.a.step 96 locating an
outer, cylindrical casing 98 which is welded to the outer
sleeve 48.
As shown in Figure 1, the casing 98 supports and
seals the upstream rear end portion of the tube 72 in a
relatively slidable manner by means of a packing gland 100,
and forms a heat exchange casing with a heat exchange fluid
inlet 102 and outlet 104. The heat exchange fluid may be
coolant water, for cooling the nozzle assembly, or steam
for heating the liquid-to-be-atomized (e.g. a coal slurry
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fuel) for lowering its viscosity, and the packing gland 100
accommodates differential thermal expansion between the
tube 72 and the casing 98.
As previously stated, the tube 72 is sealed around
S a rear end portion of the tube 68 in a relatively.slidable
manner by the differential thermal expansion accommodating
gland 106, which is a packing gland, and has an inlet 108
for liquid-to-be-atomized.
The tube 68 is sealed in a slidable manner around
a rear end portion of the shaft 64 by a gland 110 and has
an atomizing fluid inlet 112.
The apparatus shown in Figures 1 and 2 was
primarily designed for use in tests as a liquid mixture
fuel atomizer and will be described, in operation, atomiz-
ing a de-ashed, pulverized coal liquid mixture fuel using
the atomizing air of a conventional oil burner assembly
~not shown) where secondary, combustion air is swirled
around the atomized fuel.
In operation, with the apparatus arranged as shown
~0 in Figures 1 and 2, atomizing air is fed along the bore of
the tube 64, through the ports, such as port 70, to the
fluid passage 46 from which it is directed as a jet in an
unobstructed manner through the mixing zone 16 along the
surface 6 of the deflector core 1. At the same time the
pulverized coal liquid mixture fuel is fed along the bore
of the tube 72 through the ports, such as port 74, to the
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liquid passage 56 from which it is directed along the
mixing
The jet of air from the fluid passage 46, flowing
along the surface 6 of the deflector core 1 causes the
pulverized coal liquid mixture to initially be held as a
hollow cone-shaped film against the flared inner surface 14
of the nozzle rim 8 so that there is negligible contact
between the fuel and the deflector core. As the cone-
shaped film of fuel travels along the mixing zone 16 it is
thoroughly mixed with the air and emerges from the mixing
zone 16 as an atomized jet.
The width W (Figure 2) of the mixing zone 16 can
be adjusted while the nozzle assembly is in use by means of
the barrel 66 and the screw threaded engagement between the
deflector core holder 20 and the inner cylindrical sleeve
36.
It should be noted that there is neglig.ible change
in the width W of the mixing zone 16 due to differential
thermal expansion because of the close proximity of the
screw threaded engagement between the deflector core holder
20 and the inner cylindrical sleeve 36 to the mlxing zone
16, and the fact that differential thermal expansions
between the shaft 64, tubes 68 and 72 and the casing 98 are
accommodated by means of the glands 66, 106 and 100
respectively.
Tests using the nozzle shown in Figures 1 and ~,
and coal-water fuel of 70 : 30 by weight ratio and No. 6
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bunker oil fue] have been made to show the efficacy of
nozzles according to the present invention.
These tests were run in an existing oil fired
utility.
The nozzle rim 8 had a minimum inside diameter of
2.25 inches (57.15 mm) and a maximum inside diameter in the
downstream direction of 2.539 inches (64.~9 mm). The
deflector core 1 had a maximum diameter of 2.460 inches
(62.48 mm) at the outlet of the mixing zone 16. The mixing
10 zone 16 had a nominal width (W) of .035 inches and the
length~ width (LJW, Figure 2) ratio was varied between 7
and 12.
These tests demonstrated the ability of atomizing
nozzles according to the present invention to atomize coal
slurry fuels which have been difficult to atomize by known
atomizing nozzles. The good atomization of these fuels by
atomizing nozzles according to the present invention is
demonstrated by the clean, recirculated flames that are
obtained with little fall out due to incomplete combustion.
From the tests it was found that with a fuel com-
prising 70 : 30 by weight ratio coal : water and an L : W
ratio of 7 : 1, a carbon conversion of >99.5~ was found to
occur by analyzing the flue gas ash content whereas the
carbon conversion under similar conditions for known
atomizing nozzles was 96.2~.
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