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Патент USA US3074371

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Jan. 22, 1963
E. c. HUGE ETAL
3,074,361
PULVERIZED FUEL BURNER
Filed Sept. 4, 1958
2 Sheets-Sheet 1
FIG. 1
INVENTORS
Ernes’r C. Huge
George Musai
W
ATTORNEY
Jan. 22, 1963
3,074,361
E. c. HUGE ETAL
PULVERIZEZD FUEL BURNER
Filed'Sept. 4, ' 1958
2 Sheets-Sheet 2
.5.
mdE.
.13:2.$4s1j2w.?i
1m ENTORS
(ON
Ernes’r C. Huge
BY
George Musa’r
ATTORNEY
United states harem
.
Patented Jan.- 22, 1953
2.
1
3,974,361
Ernest {1. Huge, Akron, and George Musat, (lantern, Qhio,
PULVERHZED FUEL BURNER
assignors to The Bahcoclr & Wilcox Company, New
York, N.Y., a corporation of New Ziersey
Filed Sept. 4, 1958, Ser. No. 758,982
11 Gains. (Cl. flit-23)
This invention relates generally to a fuel burner and
more particularly to an improved pulverized fuel burner.
It has been observed in pulverized fuel burners that in
spinning or whirling a mixture of pulverized fuel and car
rier air axially through a burner nozzle, the major portion
of the fuel particles tends to concentrate along the inner
surface of the nozzle. In doing so the fuel assumes the
form of a “spiral rope.” For this reason the fuel is not uni~
formly distributed about the entire circumference of the
nozzle at its discharge end. Thus, the “spiral rope effect”
results in a major portion of the fuel being discharged
over only a relative small segment of the nozzle circum~
ference. This undesirable, heavy, localized fuel, discharge
3,9743%
""ig
the “rope effect,” means for relieving the low pressure area
created, by the whirling mass of fuel and air within the
nozzle to prevent a back?ow thereat and means for intro
ducing secondary air adjacent the discharge end of the
nozzle whereby the latter is effectively distributed across
the entire area of a burner opening in a furnace 'wall asso.~
ciated therewith.
A feature of this invention resides in the provision of
helical ribs disposed on the inner surface of the burner
nozzle and twisted in a direction opposite or counter to
the whirling movement of the fuel and air stream ?owing
axially thereto.
Another feature resides in the provision of an inner
nozzle having an inlet end portion in communication with
said volute chamber and through which a portion of the
fuel and air mixture ?ows to relieve the low pressure
area created by the whirling mixture ?owing axially there
of.
Another feature resides in the provision of a secondary
air means having a duct concentrically disposed about the
discharge end of the nozzle for dividing the secondary
results in certain portions of the furnace receiving too
air into an inner and outer band to distribute the air
much fuel and too little air while other portions thereof
more effectively over the entire area of the burner open
receive, conversely, too little fuel and too much air.
mg.
It has been further noted in pulverized fuel burners in 25
Still another feature resides in the use of skimmer vanes
which the mixture of fuel and air is whirled axially of a
disposed within the volute chamber for dividing the fuel
burner nozzle that a relatively low pressure zone is created
and carrier air mixture into a plurality of streams and
at the center of the whirling mixture. This low pressure
thereby assisting the ribs in discharging the fuel and air
mixture uniformly about the entire circumference of the
area results in a ‘back-?ow of the fuel and air to occur
thereat and leads to coking and/or burning within the
burner nozzle.
Also in burners of this type secondary air is generally
introduced through an air register adjacent the discharge
end of the ‘burner nozzle with the register imparting a
spin to the secondary air. Because of the spin, a large
portion of- the secondary air is concentrated in only a rela
tively narrow band which tends to hug the inner periphery
of the burner port or throat. For this reason the second‘
ary air is not uniformly distributed over the entire area of
the throat opening and consequently mixing of the fuel 40
with the secondary air is not thorough or complete. Be—
cause of the unequal distribution of the pulverized fuel
due to. the “spiral rope effect” and the incomplete mix—
ing of the secondary air with the fuel, poor combustion
and ine?‘icient utilization of the fuel is had. This in turn
lowers the e?iciency of the furnace or unit ?red thereby.
An object of this invention is to provide an improved,
pulverized fuel burner in which the “spiral rope effect”
or concentration of the fuel which is formed along the
inner surface of the burner nozzle is broken up and dis—
persed so. that a uniform distribution of fuel is had about
the entirecircumference of the burner nozzle as the fuel
nozzle upon discharge therefrom.
The various features of novelty which characterize our
invention are pointed out with particularity in the claims
annexed to and forming. a part of this speci?cation. For a
better understanding of the invention, its operating ad
vantages and speci?c objects attained by its use, reference
should ‘be had to the accompanying drawings and descrip
tive matter in which we have illustrated and described pre
ferred embodiments of the invention.
In the drawings:
FIG. 1 is a side view of a pulverized fuel burner in
accordance with this invention having portions thereof
broken away and. shown in section.
PEG. 2 is the sectional view taken along line 2—2 of
FIG. 1, having portions thereof broken away.
FIG. 3 is an enlarged detailsectional- side view of the
outer nozzle.
FIG. 4 is an end view of FIG. 3.
Referring to FIG. 1, the burner 10 of the instant‘ in
vention, designed to burn a pulverized fuel, such as coal
and the like, is illustrated in association with a. furnace
wall 11-. A burner opening in wall 11 is de?ned by frusto
conical burner throat 12, As shown, the inner surface
is discharged therefrom.
of the throat diverges toward. the furnace side of the wall
Another object is torelieve the low pressure zone cre—
and is cooled by ?uid cooled tubes 13.
ated at the center of the nozzle to prevent the occurrence 55
Spaced from the furnace wall 11 is an outer burner
of back-?ow of fuel and air thereat.
wall 14- which de?nes therebetween an air plenum cham
And still another object of this invention is to introduce
ber 1-5 in which combustion air from an air blower (not
the secondary air in a manner whereby it is uniformly de
shown)v is delivered to a burner windbox 16 located with
livered over the entire area of the burner throat or open
in the air plenum chamber 15. A damper 17 operated
ing so as to thoroughly and completely mix with the fuel 60 by a suitable operating means 18 controls the amount of
entering a furnace.
air entering the windbox.
The foregoing objectsand advantages of this invention
Located in the burner wall 14 in axial alignment with
are attained by a pulverized fuel burner comprising essen
the burner throat 12 is a circular access opening 19. Ac.
tially of a tubular nozzle having an inlet and discharge
cording to this invention the burner it} includes a cylinr
end, means in communication with the inlet of the nozzle
drical nozzle 20 which extends through the access open
and forming a volute chamber for receiving and spirally
ing closure 21, across the air chamber 15 and windbox
?owing a mixture of pulverized fuel and carrier air axial
16 to a‘point adjacent to the burner throat 12. Connected
ly along the nozzle whereby the pulverized fuel tends to
to the inlet end 263A of the nozzle is a means forming a
concentrate in a “spiral rope” fashion along the inner
volute chamber 22. As shown the volute chamber 22 is
surface thereof, a plurality of helical ribs twisted in a di 70 bounded by a pair of side walls 23-, 24 spaced apart by
rection counter to the rotation or spiral of the “rope”
a transversely extending curvilinear plate 25 de?ning a
formation on the inner surface of the nozzle for dispersing
scroll.
3,074,381
4
Air-borne pulverized fuel is delivered to the scroll or
volute chamber 22 through an inlet duct 26 entering sub
As best shown in FIGS. 3 and 4, the ribs 29 are illus
trated as rectangular in cross-section. Also that the lon
stantially tangential of chamber 22. The fuel is dis
gitudinal extent of the ribs along the inner surface of the
charged therefrom through an axial opening 27 which is
nozzle equals approximately three or four times the
in communication with the inlet end 29A of the nozzle
inside diameter of the nozzle, and that optimum distribu
29. The fuel and carrier air thus delivered to the volute
tion is obtained when the ends of the ribs terminate
chamber 22 has imparted thereto a whirling or spinning
slightly inwardly of the discharge end 2013 of the nozzle.
movement as the fuel-air mixture ?ows from the tan
In order to prevent back?ow of the fuel and air within
gential inlet to the axial outlet of the volute chamber.
nozzle 20, an inner nozzle 30 is concentrically disposed
in doing so the fuel and air mixture continues to whirl 10 therein and forms therewith an annular chamber 31
as it ?ows axially through nozzle 20. As the fuel and
through which the main fuel and air streams ?ow. Re
air is Whirled through the nozzle the heavier solid par
ferring to FIG. 2 it will be noted that the inner nozzle
ticles of fuel tend to form a “spiral rope,” and at the
36* has a flared or bell shaped, inlet end portion 32, which
center of the whirling mass of fuel and air there is cre
extends through the axial opening 27 and into the volute
ated a low pressure zone.
15 chamber 22. With this arrangement a small portion of
Because of the “spiral rope” effect the fuel is not uni
the fuel and air mixture within the volute chamber 22 is
formly distributed about the entire circumference of the
permitted to ?ow axially through the inner nozzle 30.
nozzle. When this occurs, the flame conditions within
Thus the pressure within the inner and outer nozzles
the furnace maybe such as to cause an exceptionally
tends to be equalized thereby relieving any low pressure
heavy ?ame in one sector of the furnace While one or 20 area which would otherwise be created at the center
more or" the other furnace sectors may have an insuffi
portion of the whirling mass of fuel—air mixture.
cient supply of the fuel, in comparison with the combus
tion air supplied. Under these conditions, incomplete
To streamline the ?ow of the fuel-air mixture and
minimize the probability of eddies at the inlet end 32 of
combustion and high carbon loss can occur.
the inner nozzle 39, a conical shaped member 33 with its
To assist in distributing the fuel and air about the 25 apex portion extending toward the inlet 32 is disposed
circumference of the nozzle 20, skimmer vanes 28 are
co-axialiy therewith to form an annular inlet chamber 34.
disposed in the volute chamber to divide the fuel and
Secondary air is supplied to the burner 10 through an
air mixture into a plurality of streams. As shown two
air register means 35 disposed adjacent to the burner
such vanes are illustrated. These divide the fuel and air
throat 12 and about the discharge end 20B of the burner
mixture into three co-axial, concentric, spiral or Whirl 30 nozzle 26. As shown, the air register 35 comprises a
ing fuel-air streams, the fuel concentrations of which are
pair of spaced annular members 36 and 37 which form
angularly displaced about the circumference of the noz
the end walls thereof. The end wall 37 adjacent the
zle. If desired the skimmer may be rendered adjustable
burner port has a laterally extending portion 38 converg
as disclosed in a copending application S.N. 589,546,
ing toward the burner port to de?ne an opening 39 for the
35 discharge of secondary air therefrom.
?led June 5, 1956, now Patent No. 2,921,542.
According to this invention a plurality of spaced, lon
Circumferentially spaced and pivotally connected be
gitudinal, inwardly extending ribs or interrupters 29 are
tween and adjacent the outer periphery of the end walls
disposed on the interior surface of the nozzle 2t) to dis
36, 37 of the air register are a plurality of register doors
perse or break-up the angularly displaced concentrations
40 adapted to pivot between open and closed position.
of the plural fuel streams to insure an ultimate uniform
With the air doors 40 in the open position the air register
distribution of the fuel and air about the entire circum
.35 is rendered in communication with the windbox 16.
ference of the nozzle discharge end 2%. As shown, the
If desired the air doors 40 may be suitably geared, linked
ribs 29 are equidistantly spaced about the inner wall of
or otherwise connected together so as to be responsive
the nozzle 20 and are ten in number.
The number of
to an operating means 41 which may be either manually
ribs, however, may vary depending upon the size and 45 or automatically controlled to operate the same. In the
diameter of a particular burner nozzle.
illustrated embodiment the operating means 41 comprise
An important feature of this invention is that the ribs
a manually operated handle suitably geared to the air
29 are rotated or twisted on the inner surface of the
nozzle in a helical direction which is counter to the spin—
doors 40. Thus, in the event that it becomes necessary
to shut off the burner, all the doors may be simultane
ning of the fuel and air streams flowing therethrough. 50 ously moved to a close by the operation of means 41 to
cut o? the air supply to the burner. It will be noted
also that the air doors in addition to admitting air into
the air register 35 in the open position thereof also im
parts to the air entering thereinto a whirling or spinning
The reverse or counter spiral twist of the ribs 29 rela
tive to the spiral ?ow of the fuel air streams through the
nozzle is utilized to effect a large angle of inter
section between the fuel-air streams and the ribs. Thus
as the fuel-air streams are whirling in a direction counter 55 movement as it exits therefrom through the axial open
to that of the ribs, the fuel particles in each stream, tend
ing to concentrate along the inner surface of the nozzle,
impinge upon the rib at an angle which breaks up the
“rope” or concentration of fuel tending to hug the inner
ing 39.
Because of the spin imparted to the secondary air, a
relatively large portion thereof is concentrated in a rela
tively narrow band which tends to hug the inner periphery
surface of the nozzle and cause some of the larger fuel 60 of the throat 12. As a result very little air is directed to
.ward the inner area of the throat 12.
According to this invention a center duct or sleeve 42
particles to be projected radially inwardly. As a result
the fuel particles are uniformly distributed about the
entire periphery of the nozzle. It has been noted by ex~
is disposed within the air register 35 and about the dis
periment that ribs 29 twisted counter to the whirl of the
charge end of the nozzle 20 to distribute the air and
fuel-air stream are more e?ective than straight axially 65 utilize more effectively the entire area of the throat open
extending ribs in breaking up the fuel concentrations.
Counter-twisting the ribs also permits the use of ribs hav
ing. With this arrangement the secondary air is divid
ed into an inner and outer band of whirling air in which
ing a smaller cross-sectional area which is important
the center duct or sleeve 42 is arranged to confine ap
from a pressure drop standpoint.
proximately 25% of the combustion air and cause that
It was ‘further determined by experiment that if the 70 portion of the air to be discharged immediately adjacent
ribs are twisted 1A3 of a turn, i.e. traverse a 45° sector
the fuel nozzle. With this arrangement more of the air
of the nozzle circumference over the length of the rib
is allowed to be thoroughly and uniformly mixed with
and counter to the flow of the fuel-air streams, satisfac
more of the fuel entering the furnace. Thus optimum
tory distribution as well as pressure drop is attained
combustion conditions are attained resulting in ef?cient
thereby.
75 and complete combustion of the fuel.
3,024,361
5
6
As shown, the burner 10 herein described may be used
separately or in combination with either liquid and/0r
gaseous fuel. For this purpose a liquid fuel assembly 43‘
may be inserted through the end wall 23’of the volute
chamber 22 to extend through the inner nozzle 30 to
ward the burner opening with its atomizing tip 44 ter
centrate along the inner surface of said outer nozzle and
another portion of each fuel and air stream ?ows axially
through said inner nozzle to relieve the low pressure
created by the mixture whirling through said annular
chamber, means adjacent to and coaxial with the inlet
end of said inner nozzle for enhancing the entrance of
fuel and air thereinto, said latter means including a coni
cal member having the apex thereof extending toward said
minating adjacent the discharge end of the nozzles.
A gaseous fuel is burned through the medium of a gas
?ared inlet end of said inner nozzle to form therewith
ring 45 positioned adjacent the burner throat 12 and about
the axial opening 39 of the air register. Gaseous fuel is 10 an annular entrance chamber, a plurality of longitudinal
ly extending helical ribs disposed on the inner surface of
supplied thereto through a supply pipe 46 which connects
to a suitable source of supply not shown.
said outer nozzle to intersect said whirling fuel mixture
Completing
the burner assembly as illustrated is an ignitor means 47‘
at a predetermined angle, said ribs being rectangular in
and a sighting means 48,.
cross-section and twisted in a direction counter to the
'
‘While the instant invention has been disclosed with 15 whirling movement of said streams flowing through said
annular chamber to increase the angle of intersection
reference to a particular embodiment thereof, it is to be
therebetween for dispersing the fuel concentration along
appreciated that the invention is not to be taken as lim
the inner surface of said outer nozzle so as to provide
ited to all of the details thereof as modi?cations and
a uniform distribution of the pulverized fuel about the
variations thereof may be made without departing from
the spirit or scope of the invention.
‘
What is claimed is:
20.
annular discharge opening formed by said nozzles, said
ribs being equidistantly spaced and extended longitudinal
l. A pulverized fuel burner comprising spaced outer and
inner tubular nozzles, each of said nozzles having an
inlet and discharge end, means in communication with
ly of said outer nozzle a distance equal to approximately
three times the diameter thereof, and an air register for
receiving combustion air disposed about the annular dis
pulverized fuel and carrier air whereby a major portion
having an axial outlet adjacent to and aligned with said
the inlet ends of said nozzles for receiving a mixture of 25 charge opening formed by said nozzles, said air register
of said mixture is whirled axially of said outer nozzle so
that the pulverized fuel tends to concentrate along the
inner surface of said outer nozzle, and a minor portion
burner port, means for imparting a whirling movement
to the combustion air ?owing through said register, and a
duct disposed within said register, said duct being con
of said mixture being directed axially through said inner 30 centrically spaced about the discharge end of said outer
nozzle, said duct dividing said combustion air into an
nozzle to relieve the low pressure created by the whirl
inner
and outer band of air so that said combustion air
ing mass of said major portion of said mixture ?owing
is effectively distributed over the entire area of said
through said outer nozzle, a plurality of longitudinally
port.
extending helical ribs disposed on the inner surface of
4. A pulverized fuel burner comprising outer and in
said outer nozzle to interrupt the ?ow of spiralling fuel n
ner
tubular nozzles cooperating to form an annular pas
therethrough at a predetermined angle, said ribs being
sage therebetween and each having an inlet and a dis
charge end, said inner nozzle. extending along substantial
ment of said mixture to enhance the angle of interruption
ly the entire length of said outer nozzle and having its
formed between said ribs and said spiralling fuel ?ow
for dispersing the fuel tending to concentrate along the 40 discharge end disposed adjacent the discharge end of ‘said
outer nozzle; means supplying pulverized fuel to. said
inner surface of said outer nozzle to enhance uniform
twisted in a direction counter to the spiralling move
nozzles, said last named means including means supply
distribution of the pulverized fuel about the nozzle dis?
ing a portion of the pulverized fuel in a whirling stream
charge opening formed by the discharge ends of said
of air to the inlet end of said outer nozzle and effecting.
nozzles, and means provided adjacent to and co-axially
a whirling path of travel through said passage. and along
with the inlet end of said inner nozzle for enhancing the 45 said outer nozzle, and means supplying another portion
entrance of said mixture thereinto, said entrance en
of the pulverized fuel in a stream of air to the inlet end
hancing means comprises a conical member having the
of said inner nozzle for flow therethrough to relieve the.
apex thereof extending toward the inlet end of ‘said inner
nozzle.
2. The invention as de?ned in claim 1 wherein said
inlet end of said inner nozzle is ?ared outwardly to form
with said conical member an annular entrance cham
ber to said inner nozzle.
3. In combination with a furnace wall having a burner
port extending 'therethrough, ‘a pulverized fuel burner
comprising means forming a volute chamber having a
tangential inlet for receiving a mixture of pulverized fuel
and carrier air, and an axial outletin axial alignment
with and spaced from said burner port, skimmer means
low pressure zone in the center of the whirling stream of.
fuel and air discharging from said annular passage; and
a plurality of longitudinally extending helical, ribs dis:
posed on the inner surface. of said outer nozzle and
twisted in a direction counter to the’dire‘ction of‘ rotation
of the whirling: stream of fuel and airentering said an
nular passage, said ribs being so proportioned and; are
ranged and twisted as to disrupt and disperse the fuel-0on1
centrations along the inner surface of said’ outei'i'nozzle
as said whirling fuel-air stream passes through said an;
nular passage and yet maintain the original direction of
rotation to
of the
provide
whirling
a substantially
fuel-air stream
uniform
in said
circumfere
disposed in said volute chaniber'to divide said mixture 60 passage
with a plurality of fuel and air streams, said volute
chamber imparting a whirling movement‘ to said streams
as the same ?ow from said- tangential inlet to said axial
outlet, an outer tubular nozzle having an inlet and dis
charge end portion, said inlet end portion being in com
munication with said axial outlet and said. discharge
end portion terminating adjacent said. port, an inner
tubular nozzle disposed within said outer nozzleland. forms
ential distribution of pulverized fuel upon discharge ‘from:
saidannular passage.
'
'
5. The invention as de?ned in claim 4 wherein said
ribs are of rectangular cross-section.
/
k
v '
6. The invention as defined in ‘claim 4v wherein said
ribs terminate slightly inwardly of the discharge end of
said outer nozzle.
7. The invention as de?ned in claim 6 wherein said
an outwardly ?ared inlet end portion extending axially 70 outer nozzle is of circular cross-section, and said. ribs
are equidistantly spaced and extend along said outer
into said volute chamber and having an outlet end por
tion terminating adjacent said port whereby a portion
nozzle a distance equal to approximately three times the
of each fuel and air stream discharging from said volute
diameter of said outer nozzle.
therewith'an annular chamber, said inner nozzle having
chamber is whirled in an axial direction through said an
8. The invention as defined in claim 7 wherein said
nular chamber with the pulverized fuel tending to con 75 ribs make an approximately 1/8 turn throughout their
3,074,361
7
lengths relative to the circumferenceof said outer noz
zle.
vide a substantially uniform circumferential distribution
of pulverized fuel upon discharge from said annular pas
9. A pulverized fuel burner comprising outer and in
sage.
11. In combination with a furnace wall formed with
a circular burner port extending therethrough; a pulver
discharge end, said inner nozzle extending along sub
ized fuel burner comprising means forming a volute cham
stantially the entire length of said outer nozzle and having
ber having a tangential inlet and an axial outlet; outer
its discharge end disposed adjacent the discharge end of
and inner tubular nozzles cooperating to form an an
said outer nozzle; means supplying pulverized fuel to said
nular passage therebetween opening to the axial outlet
nozzles, said last named means including means form 10 of said volute chamber, said outer nozzle having an inlet
ing a volute chamber opening to the inlet ends of said
at one end opening to the axial outlet of the volute cham
nozzles, means for introducing a stream of air and pul
ber and an outlet at its opposite end concentrically open
verized fuel tangentially into said volute chamber and
ing to said burner port, said inner nozzle having at one
ner tubular nozzles cooperating to form an annular
passage therebetween and each having an inlet and a
effecting a whirling path of travel therein, means directing
end an outwardly ?aring inlet opening to and disposed
a portion of said whirling fuel-air stream to the inlet 15 within said volute chamber and an outlet at its opposite
end of said outer nozzle and effecting a whirling path of
end, concentrically opening to said burner port, said inner
travel through said passage and along said outer nozzle,
nozzle extending along substantially the entire length of
and means directing the remaining portion of said Whirl
said outer nozzle and having its outlet end disposed adja
ing fuel-air stream to the inlet end of said inner nozzle
cent the outlet end of said outer nozzle; means supplying
for flow therethrough to relieve the low pressure zone in 20 pulverized fuel to said nozzles, said last named means
the center of the whirling stream of fuel and air dis
including said volute chamber, means for introducing a
chargnig from said annular passage; and a plurality of
stream of air and pulverized fuel into the tangential inlet
longitudinally extending helical ribs disposed on the in
of said volute chamber and effecting a whirling path of
ner surface of said outer nozzle and twisted in a direction
travel in said chamber, and means including said ?ared
counter to the direction of rotation of the whirling stream 25 inlet end of said inner nozzle for directing a major por
of fuel and air entering said annular passage, said ribs
tion of said whirling ‘fuel-air stream to the inlet end of
being so proportioned and arranged and twisted as to dis
said
outer nozzle and effecting a whirling path of travel
rupt and disperse the fuel concentrations along the inner
through said passage and along said outer nozzle and
surface of said outer nozzle as said whirling fuel-air
stream passes through said annular passage and yet 30 for directing the remaining portion of said whirling fuel
air stream to the inlet end of said inner nozzle for flow
maintain the original direction of rotation of the whirling
therethrough to relieve the low pressurze zone in the
fuel-air stream in said annular passage to provide a sub
center of the whirling stream of fuel and air discharging
stantially uniform circumferential distribution of pul
from said annular passage; a plurality of longitudinally
verized fuel upon discharge from said annular passage.
10. A pulverized fuel burner comprising means form— 35 extending helical ribs disposed on the inner surface of
said outer nozzle and twisted in a direction counter to
ing a volute chamber having a tangential inlet and an axial
the direction of rotation of the whirling stream of fuel
outlet; outer and inner tubular nozzles cooperating to
and air entering said annular passage, said ribs being so
form an annular passage therehetween opening to the
proportioned and arranged and twisted as to disrupt and
axial outlet of said volute chamber, said outer nozzle
having an inlet at one end opening to the axial outlet of 40 disperse the fuel concentrations along the inner surface
of said outer nozzle as the whirling fuel-air stream passes
the volute chamber and an outlet at its opposite end, said
through said annular passage and yet maintain the orig
inner nozzle having at one end an outwardly ?aring inlet
inal direction of rotation of the whirling fuel-air stream
opening to and disposed within said volute chamber and
in said annular passage to provide a substantially uni
an outlet at its opposite end, said inner nozzle extending
form circumferential distribution of pulverized fuel upon
along substantially the entire length of said outer nozzle
discharge from said annular passage to said burner port,
and having its outlet end disposed adjacent the outlet end
and
means supplying inner and outer whirling bands of
of said outer nozzle; means supplying pulverized fuel to
secondary air to said burner at a position adjacent the
said nozzles, said last named means including said volute
outlet ends of said nozzles, said last named means in
chamber, means for introducing'a stream of air and pul
verized fuel into the tangential inlet of said volute cham 50 cluding a sleeve surrounding and spaced from said outer
nozzle and‘ having an outwardly ?aring inlet at one end
ber and effecting a whirling path of travel in said cham
and an outlet at its opposite end disposed in a plane com
ber, and means including said ?ared inlet end of said
mon to the outlet ends of said nozzles and extending nor
inner nozzle for directing a major portion of said whirling
mal to the axes of said nozzles.
fuel-air stream to the inlet end of said outer nozzle and
effecting a whirling path of travel through said passage 55
and along said outer nozzle and for directing the remain
ing portion of said whirling fuel-air stream to the inlet
end of said inner nozzle for flow therethrough to relieve
References Cited in the ?le of this patent
UNITED STATES PATENTS
of fuel and air discharging from said annular passage; and 60
a plurality of longitudinally extending helical ribs dis
posed on the inner surface of said outer nozzle and twisted
1,738,176
2,275,394
2,284,708
2,325,442
2,485,656
in a direction counter to the direction of rotation of the
2,912,942
the low pressure zone in the center of the whirling stream
whirling stream of fuel and air entering said annular pas
sage, said ribs being so proportioned and arranged and 65
twisted as to disrupt and disperse the fuel concentrations
along the inner surface of said outer nozzle as the whirl
ing fuel-air stream passes through said annular passage
and yet maintain the original direction of rotation of the
whirling fuel-air stream in said annular passage to pro
Dyer ________________ __ Dec. 3,
Hardgrove __________ __ Mar. 3,
Woolley ____________ __ June 2,
Vroom _____________ .._ July 27,
Raskin _____________ __ Oct. 25,
Whitney et al _________ __ Nov. 17,
1929
1942
1942
1943
1949
1959
FOREIGN PATENTS
311,905
375,767
Great Britain ________________ __ 1929
Great Britain _______________ .__ 1932
377,474
775,730
Great Britain _________ ,_ July 28, 1932
Great Britain ________ __ May 29, 1957
30,593
Netherlands __,_:__.______ Aug. 15, 1933
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