Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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K 5624
MIX AToMIZER
m e invention relates to a mix atomizer for the atomization
of a liquid with gas. m e invention further relates to an
apparatus for the atomization of a liquid, which apparatus is
provided with a plurality of such mix atomizers.
m e term liquid is taken throu~hout the specification and
claLms also to include dispersions of solid particles in a
liquid and emLlsions.
Atomizers are applied on a large scale in combustion
engineering, especi~lly for atomizing heavy liquid fuel, to
promote intensive contact of liquid with ccmtwstinn air for a
proper combustion. In an atomizer liquid fuel is brcken up into
very small droplets which droplets may be subsequently mixed
with oxygen or an oxygen-containing gas, for example air, in a
combustion chamber for combustion of the fuel. Abomization is
normally effected by QUsing a liquid to spurt undes pressure
frcm one or more orifi oe s with special shap~ and dimensions.
Addition of a gas, for example steam, to the liquid ~n the
abcmizer itself yromotes the atamizaticn of the liquid. An
atomizer wherein gas is added to the liquid to be atomized is m
the specification and claims in~icated with the expression m~x
atomizer. ~hen a fuel is to be atom~-ed it is of importance to
generate sprays of liquid droplets which are substantially
uniformly distributed over the outlet area of the atamizer, in
order to promote an optim21 oo~bustion of the liquid in the
oo~bustion chamber.
Although the elucidation of the present inventicn to be
given heseinafter will deal mainly with steam atomization of
liquid, such as oil, it is explicitly stated here that the
application of the proposed atamizer is not restricted thereto.
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Steam may be replaced by, for example, air or refinery fuel gas.
m e steam may also be saturated to wet. Apart from application
in combustion installations atomizers of the proposed type can
also be used in spraying installations, for instance, for the
purpose of the vaporization of a volatile c~onent.
m e object of the present invention in to provide a mix
atomizer for the atomization of a liquid with a gas which
apparatus is so designed that the velocity and flux of the
liquid leaving the atomizer during operation are substantially
uniformly distributed over the outlet area of the atomizer, in
order to generate hcm~g#ne~s liquid sprays, promoting optimal
use of the liquid for combustion or other purposes.
m e mix atomizer for the atomizatiQn of a liquid with gas
according to the invention thereto comprises a first mixIng
chamber provided with inlet ~eans for supplying a liquid and
primary gas to form a mixture of liquid and gas, said first
mixing chamber debouching into a second mixing cha~ber having
crDss-sectional areas being substanti~lly larger than the
cross-sectional areas of the first nux m g ch2mber, means for
tangentially supplying secondary gas around the mixtLre of
liq~id and gas passing through the secGnd mixing chamber during
operatiQn, the second mixing chamber debauching into an outlet
nozzle, having cross-sectional areas being substantially snaller
than the cross-sectional areas of the second mixing chamber, the
first mixing chamber, the seoond nixlng chamber, and the outlet
nozzle having substan~ y coinciding longitudinal axes.
In a suitable embodiTent of the inve~tion a plurality of
the abcwe-mentioned atcmizers are oombined in a single apparatus
for atomization of a liquid, said apparatus having a single
liquid supply and a single gas supply serving the plurality of
mix atomizers.
The invention therefore further relates to an apparatus for
the atomization of a liquid with gas, comprising a member havinq
a longitudinal axis and being internally provided with a plurality
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of mux atGmizers according to the invention, terminating at the
outer surface of a head of the member, the member being inter-
nally prGvided with one liquid supply channel and one gas supply
channel, first passages forming fluid coomunications between the
liquid supply channel and the first mixlng chambers of the mix
atomizers, second passages for supplytng primary gas from the
gas supply channel into said first muxing chambers, and third
passages for tangentially supplying secondary qas from the gas
supply channel into the second muxing chambers of the mux
atcmizers
m e invention will now be described by way of example only
in more detail with reference to the acccmpanying drawings, in
which
Figure 1 shows a longitudinal section of a mix atomizer
according to the invention.
Figure 2 shows a longitudinal section of an apparatus for
the atomazation of a liquid prcvided with a plurality of mux
atomizers accvrding to the invention, and
Eigure 3 shows a top view of the apparatus shcwn Ln
Figure 2.
Figure 1 shcws a mix atomizer, generally indicated by
reference numeral 1, for atomizing a liquid, such as a heavy
liquid fuel, with a gas. The mix atcmizer 1 has as main
c ~ ents a first muxing chamber 2, a second chamber 3 being Ln
fluid ccnm~nication with the f~rst muxing chamber 2, and an
c~tlet nozzle 4 ccnnected with the seccnd mixing chamber 3.
These three components have substanti~lly coinciding longitur
dinal axes, while the c~vss-secticnal areas of the seccnd mux1ng
chamber 3 and those of the cutlet nozzle 4 are koth substan-
tially l~rger than the cross-sectional reas of the fir5t mixLng
chæmber 2. FUrthOE, the cross-sectional areas of the outlet
nozzle 4 are chosen small r than the cross-sectional areæs of
the second mixIng ch3mber 3. Channels 5 and 6 æ e arranged in
the atcnuzer for supplying a liquid to be atomized and atomizing
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gas, respectively, m to the first muxing chamber 2 at or near
the free end thereof. The channels 5 and 6 are positioned at an
angle with respect to one another to promote intensive break-up
of the liquid flow issuing frnm channel 5 by the gasflow from
channel 6.
For supplying gas into the second mux mg chamber 3 the mux
atomizer is provided with a ring-shaped channRl 7 with passages
8 formlng fluid com~unications between the channel 7 and said
muxing chamber 3. These passages 8, being preferably unifor~ly
distributed over the cir,cumference of the second mixing chamber
3, are so positioned with respect to said second mixing cha~ber
that gas from the ring-shaped channel 7 is tangentially intro-
duced into said mixIng chamber 3.
Downstre~m of the rinq-shaped channel 7 the second mixing
chamber 3 has a substantially frusto-co.nic~lly shaped side wall
9 tapering towards the outlet nozzle 4 thereby prcviding a
smcoth guiding for fluid from the channel 7 and the passages 8
towards the outlet nozzle 4.
During operation of the mix atomizer shown in Figure 1 for
the atomizatian of liquid fuel with st~n, the liquid to be
atanized and steam are introduced into the f~rst snixing chamber
2. Owing to the iTlpact of the stean flow on the supplied liquid
flow, the li~uid flaw is bro3cen up into small liquid frag~nts
in the first. miscing chanber 2. The brea}cing up of the liq~lid
flaw is pro~ted by causing the steam from the channel 6 to
cantact the liquid flaw f~-~.- the channel 5 at an angle. I~e so
formed m~re of liqu~d frag~nts and steam enters the second
m~xing challb~ 3, where Sff~y stez~n is added at son~c
velccity to said m~re. Since the s~dary steam is tangen-
tially intra~ at a high velocity into the seccmd mixing
chalrber at a wide part thereof, the sec~3ary steam will form an
annulus ar ~3d the core forned by the mix ~re of liquid :fL~grl~lts
and primary steam frcm the first mlxing ch3mber 2. The ~ajor part
of the tangentially introduced steam flows substantial~y Along
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the frusto-conically shaped wall 9 of the second mixing chamber
3 and follows its way along the wall of the outlet nozzle 4,
thereby preventing direct contact of liquid with said wzlls.
Such a contact might easily reduce the velocity of the liquid
flowlng close to said walls, resulting in an irregular outflow
pattern of the liquid over the outlet nozzle 4.
Since the cross-sectisnal æeas of the outlet nozzle 4 are
substantially smaller than the cross-sectional areas of the
second mixing cha~ber 3, the velocity of the mixture of steam and
liquid fragments is substantially increased in the outlet nozzle
4, causing a further break-up of the liquid fragments. Owing to
the presence of a shield of the tangentially supplied seccn~ry
steam the velocity and the density of the liquid fragments over
the cross seCtiQn of the outlet zzle 4 will be substan~ ly
uniform, which feature enables an effective ccmbustion of the
liquid in a not shcwn combwstion chamber arranged dcwnstDeom of
the outlet nozzle 4. Upon leaving the mux atomizer the l;quid~
steam mixture will rapidly expand, result mg in the formation of
a mist of very fine liq~id droplets in the combusticn space,
20 ' where the liquid droplets are contacted with blast for th~
ccmbustion of the fuel.
Reference is now made to Figures 2 and 3 showing an
apparatus for atomizing liquid, which apparatus is prcvided with
a plurality of mix atomizers of a type discussed in the above
with referen oe to Figure 1.
This atc~ization apparatus ccmprises a memker 10 provided
with a central channel 11 for the supply of atcmizatic~ fluid to
a plur lity of mix atcmizers 12, and with a concentrically
positioned annular channel 13 for the supply of liquid, such as
oil, to be atamized. The mix atomizers 12 are arranged in a head
14 of the aFparatus 10.
m e distanoe between the outlet nozzles of adjacent mix
atamizers 12 should be chosen sufficiently large to prevent
interferen oe between adjacent outflowing streams of liquid
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droplets. A suitable arrangement of the mlx atomizers 12 is the
one shcwn in Figure 3, wherein the centres of the outlet nozzles
of the mlx atomizers 12 are positioned in a circular pattern,
and wherein adjacent outlet nozzles are spaced apart from one
another at 120 degrees. As shcwn in Figure 2 the head 14 of the
apparatus 10 is frusto-ccnically shaped whereas the mix atomizers
12 are arranged perpendicular to the outer surfa oe of said head
14. m is arrange~.ent enables the application of more mux atomizers
without the risk of interference between adjacent mux atomizers
than possible when using an apparatus having a flat head and the
mix auomizers being arranged perpendicular tD the flat outer
surface of the hP~d.
Each mix atomizer 12 is prGvided with a first muxing
chamber 15, a second muxing ch2mber 16 and an outlet nozzle 17,
wherein the second mux m g chamber 16 is substantiaily wi~Pr than
the first moxing chamber 15. m e first mixlng cha~ber 15, the
second muxing chalber 16 and the outlet nozzle 17 of eash mix
atomizer 12 have coinciding longitudinal axes, positioned
perpendicular to the frusto-conically shaped outer surfaoe of
head 14.
For supplying primary abomization fluid to the mox
atamizers 12, a plurality of passages 18 are provided formong
fluid communications ~etween the central channel 11 and the
f~rSt mix;ng ~ s 15. Sec~ndbry atcmization fluid is
supplied via tangentially arranged passages 19 to the seoond
m~xing chsmbers 16 of the mix atamizers 12. These pas a~es 19
form fluid commL m caticns !between the mix atomizers 12 and a
substanti~lly ring-sh2ped channel 20 cconectcd to the oe ntral
channel 11 via a passage 21. For the supply of seccndary
3o atomization fluid to the mux atamizers 12 via tangenti~lly
arranged p2ssages 19 as shcwn in Fiqure 2, the ring-shaped
channel 20 surrounds the m~x abomizers 12.
Fluid to be atomized i9 supplied to the first mixing
chambers 15 of the ~ix abomizers 12 via a plurality of passsges
22 forming a fluid communication between the annular liquid
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channel 13 and the first muxing chambers 15.
The operation of the apparatus shown in Figures 2 and 3 is
substantially the same as discussed with reference tc the
separate mix atamizer shown in Figure l. When using the apparatus
shown in Figures 2 and 3 for the atomization of oil with steam,
the mlx atomizers 12 are supplied with oil and steam via a
common liquid supply, viz. annular channel 13, and a common
steam supply, viz. central channel 11, respectively.
It shculd be noted that the present invention is not
restricted to mox atomizers having second mixing chambers with
frusto-conically shaped walls downstream of the seoondary steam
inlets. Instead ~hereof, other shapes of tapering walls may be
applied, pro~ided that there is a smooth passage for the
secondary steam from the seccnd]ry steam inlets to the autlet
nozzle of the mix atomizer, guaranteeing ~hat the soc~od~ry
steam will form a shield flowing alang the walls of the seoond
mixing chamber and the outlet nozzle.
Althcugh in the embodimcnts shown the mux atomizers are
provided with oentral pri~ary ste~m inlets in ccmbination with
side inlets for liquid, these inlets may also be cthcnwi~e
arranged, for example a oc~bination of central liquid inlets
with side primary steam inlets may be chosen for.
Further, the i~vention is not restricted to an apparatus
with mix atomizers having the particular arrangement of a
centr~l steæm channel and an annular liq~id channel ~ shown in
Fig~re 2. Any o~her suitable arrangement may be applied,
provided that the mix atomiz 0 can be supplied with steam and
liquid frcm a comman steam channel and a oc~mon liquid channel,
respectively.
F;nAlly, it is noted that the Lnvention is not restricted
to an ap~aratus for atomization of a liquid having a frusto-
oonically shaped h~d. Instead thereof the apparatus can be
prcvided with a flat-shaped head. With such a head the mix
atcmizers are preferably arranged at an acute angle with respect
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to the cuter surface of the head having their cutlet nozzles
pointing away fr~-, one another to enable the positioning of a
relatively large number of mix atomizers in the apparatus
without the risk of interference between the fluid flows issuing
from the atomizers dur mg operation.
