Note: Descriptions are shown in the official language in which they were submitted.
C~lldlal~ Pat~e~ plication 2131~8KLS COllsultin I~B
No. KLS-012-~ Po/McG/IIl
Burner for Liquid Fuels
.
The invention relates to an apparatus ~or burning liquid
fuels when introduced into a combustion chamber, where the
10 fuel can be an atomized liquid or a pulverized solid fuel
atomized witll a suitable liquid.
Various burners are avai.lable in the art for combusting
liquid fuels such as oil. of different grades as well as for
15 combusting solid fuels, particularly coal, peat or t~le like
in pulverized form. Pulverized solid fuels are normally
introduced illtO a combu~tion chamber as a mixture of t~le
solid fuel with a carrier liquid such as water or oil in
tile form of an emulsion. In practice, combhstion of sus-
20 pended soli.d fuels has proven relatively difficult. Prob-
lems often arise due to clogging of the fuel ports or
nozzles, wllich can lead to irregular fuel and air supply,
causing a reduction in combustion efficiency.
The US Patellt 4,726,760 discloses a burner by W~liC~I a cen-
tral injection port opening into the combustion chamber is
provided witll a continuous knife edge facing the center
axis of the port. A plu~-ality of air inlet ports are evenly
distributed about tlle circumference of the knife edge port
and the inlet ports are connected to a variable source of
compressed air to aid atomization.
Even Wit~l tllis arrangement o~ the US Patent, the atomiz-
ation of tlle fuels coulcl be improved. The mixing of the
i
- 2 - 21817~18
uel3 Wit~l air also appears to be insufficient, limiting
tlle acllievable degree oE combustion efficiency.
It is tllerefore an obje~-t of tlle present inven~:ion to prov-
5 ide an apparatus for burning liquid fuels by whicll atomiz-
ation of tlle fuel can be improved and by which a better
mixing of the atomized Euel with combustion air can be
acllieved to thereby improve combustion efficiellcy.
lo ~ummarv of the i nventi
In accordance wit~l tlle ]?resent invention, an apparatus for
burning liquid fuels to be introduced into a combustion
chanlber is provided, wllere t~le liquid fuels preferably
15 comprise lleating oils or heavy oils. In adaition, solid
fuels in pulveri:~ed form such as lignite coal, bituminous
coal, gas coal, I?eat or the like can be f ired w~lell admixed
to a suitable carrier liquid.
2~ T~le apparatus comprises a central port arranged at a down-
stream end along a longitudinal axis of tlle apparatus,
wllic}l serves as t~le supl~ly opening into a combustion c~lam-
ber. A rirst plurality of inlet ports are arranged Goncen-
trically about the longitudinal axis ~or introducing a
25 first fuel and/or air f~ ow into a space immediately up-
stream of tlle central port. These inlet ports preferably
supply a relatively lligll-speed air flow from a compressed
air source. More preferably, tlle center axes of tlle inlet
ports are arranged sliglltly oblique to a radial direction
30 rom tlle longitudinal a}2is, to thereby impart a rotational
or vortex-type motion in the fuel-air mixture to be formed.
A second plurality of irllet ports is also arranged concen-
trically about the longi.tudinal axis, wllere tllis second
35 plurality of inlet ports introduces a second fuel and/or
., ~
~ 3 - 218 1~48
air flow, wllich substantially intersects the inlet flows of
the first plurality of inlet ports. T}le second plurality of
illlet ports preferably ~lave their center axes arranged ge}l-
erally alollg t~le longitudinal direction. Prererably t~le
5 first and second plurality of inlet ports comprise the same
number of ports respect ively and the flow from the res-
pective ports intersect when entering the space before tlle
central port at an angle of about 60 to 90.
10 In a preferred embodiment, tlle first plurality of ports in-
ject compressed air int~ the space, while t~le second plur-
ality of ports inj ect fuel at an intersecting angle of
about 90 witll the comp]^essed air flow.
Witll tlle ahove arrangement of intersecting inlet ports,
llighl; ef~icient atomization of tlle liquid ~uel can be ob-
tained wit~l respect to droplet size and distribution. In a
preferred embodiment, vortex flow can be simultaneously
ac~lieved of the fuel-ai]^ mixture exiting the central port
20 of: t~le burner.
Brief descriPtion of t;he drawinqs
Tlle invention will IIOW ~e described in more detail Wit~l
25 reference to an embodiment of the apparatus as illustrated
in tlle drawing of Figs. 1 and 2.
Fig. 1 sllows a cross-section along the longitudinal axis of
tlle burner apparatus according to an embodiment of f:he
30 presellt invention.
Fig. 2 shows a preferred arrangement of the ~irst inlet
ports witll respect to t~le second inlet ports.
~ 4 ~ 21817~8
T~le elements necessary for the actual operatioll of ~ e
burning apparatus of the present inve~ltion, for example air
sources and fuel sources as well as tlle combustion c~lamber
itself are not shown in the drawing, ~lowever will be known
5 to tllose skilled ill t~le present art.
Detailed descril~tion of the preferred embodiments
The fuel burner illustrated in Fig . 1 comprises a j et body
36 extending about a longitudinal axi6 26. Tlle downstream
end of tlle jet body 36 is fitted Wit~l a nozzle piece 50
wllich comprises a central fuel port 10 opening into a com-
bustion c~lamber 16 (not shown in detail). The flow direc-
tiOII is indicated by the arrows ill the lef t of Fig .
15 indicating f~lel and/or air streams flowing toward the
nozzle piece 50. The central port 10 is preferably recessed
or disposed upstream of an end wall IZ of t~le combustion
chamber 16 as will be discussed below.
20 Tlle jet body 36 is surrounded by two gas and/or air pass-
ages 14, 18. The passage 14 opens into the combustion cham-
ber 16 at its downstream end via an annular inlet port 24.
~le passage 14 supplies primary air for combustion, w~lich
may be ellriched Wit~l higher temperature combustion gasses
25 in a recyclillg system. The term "primary air" used ~lereill-
after is to be understood as air or a mixture of air and
recycled combustion gasses. The air exiting t31e annular
port 24 llas a flow velocity of about 100 to about 200
m/sec., preferably 120 to 140 m/sec.. The side walls 20 and
30 22 defining t~le annular port 24 are of conical configur-
ation to provide a cone-shaped air flow wllich broadells as
it enters t~le combustion chamber. Swirl or baffle plates
are provided in passage 14 at an angle of about 70 to
t~lereby give t~le primary air a vo~tex movemellt about the
35 longitudinal axis 26. T~le primary air is supplied to tlle
I
21817~8
passage 1~ at a pressure o~ about 1000 to about 1200 mm
E~20 ~
~ second passage 18 is ~)rovided concentrically about pas-
5 sage 14 and defined by cln inner jacket 38 and an outer
~acket 3g. Passage 18 at its downstream end merges into a
second annular inlet port 28 defined by tlle conical side
walls 30 and 32. Tlle second annular inlet llowever is dir-
ected to form a converg-ing conical flow of secondary air,
10 W~liC~ ltersects Wit~l tl~e f~rpi:~n~l; ng conical profil~ of
primary air from tlle fi]-st annular input port 24. Swirl
baf1es may also be located in passage 18 to impart a vor-
tex ~low of secondary air if desired. 1~ deflection angle of
40 to 45 of tlle baffl~s with respect to tlle lollgitudinal
15 axis 26 is preferred. T~le discharge of velocity oi tlle
secondary air is preferably in the rallge of 120 to 180
m/sec., more preferably 130 to 150 m/sec.. T~le intersection
of tlle collically converging secondary air witll Lhe conic-
ally ~p~n~ g primary air provides additional agitation
20 and mixing of ~ e fuel-air mixture sllortly aLter it enters
illtO ~le combustion cha~nber 16. The secondary air is pref-
erably fed into tlle passage 18 at a pressure of about 1000
to abo~lt 1200 mm H2O. Tlle vortex deflectioll angle of tlle
secolldary air when employed is preferably in t~le same dir-
25 ection as t~le deflectioll of the primary air. ~s with tlleprimary air, tlle secolldary air can also be admixed witl
combustion gasses from the furnace as desired.
Tlle discllarge velocities of the primary and secondary air
30 from tlle annular outlets 24 and 28 respectively gellerally
remain tlle same under most operating conditions from start-
up to full load. Depend:ing on tlle ~pe of fuel being com-
busted, tlle discllarge velocity and/or discllarge volume can
be varied by increasing or decreasing the gap widtll of the
35 annular ports 24 and 28. This is accomplis~led by axial
- 6 - 21817~8
displacement of t~e annular mout~l piece 34 connected Wit~
~ile tubular jacket 33 which separates tlle two passages 14
alld 18.
5 Ill accordance Wit~l the present invention, the burner appar-
atus is provided with a particular configuration of tlle
nozzle piecc 50, whicll comprises the central port 10.
Embodimellts of tlle nozzle construction are sllowll in Figs. 1
and 2. Ill the preferred embodiments, t~le central port 10 is
10 defined by a continuous, circular knife edge 40 facirlg tow-
ard the longitudinal axis 26. The knife edge has taperillg
side portions seen in cross-section and, preferably ~las a
triangular-like cross-section Wit~l sloping sides 43 as
sllown in Fig, 1.
: ' -
According to the invention a first plurality of air inlet
ports 42 are! arran~ed ccncentrically about tlle longitudinal
axis 26 for introducing a first fuel and/or air flow into a
space 49 located upstream of the central port 10. The space
20 49 is gellerally of cylindrical form and communicates witll
bot~l tlle i:irst inlet ports 42 and the second inlet ports 47
to be discussed below. ~'he inner surface 60 of ~lle nozzle
piece 50, whlc~l faces the part 10 may be concave in shape
as shown in Fig. 2.
Preferably, th~ first plurality of inlet ports 42 are in
common fluid: communication with a compressed air passage 46
by means of an annular passage 44. The inlet ports 42 are
defined by a center axis for each port respectively, w~ich
30 generally determines t~le flow direction into the space 49.
Preferably tlle center a}ces of the inlet ports 42 are
arrangod at an angle in the range of 60 to 90 witll
respect to the longitudinal axis 26, preferably at an angle
in the range of 70 to ~0
.,
~ 7 ~ 21817~8
A second plurality of in.let ports is also arranged concen-
trically about the longitudinal axis 26 in the nozzle piece
50. T~lese 6econd inlet E~orts 47 are arranged to introduce a
second fuel and/or air flow into the space 49, where tlle
second flow from tlle inlet ports 47 substalltially illter- =
sects the first flow from the inlet ports 42 as can best be
seell in Fig . 3 . Fig . 3 represents a f ront view along the
longitudillal axis 26 looking in tlle upstream directioli.
The second plurality of inlet ports 47 as seen in Fig. 1 or
Fig. 2 are defined as each having a center axis arranged at
an angle in tlle range of 0 to 30 Wit~l respect to tlle
longitudinal axis 26.
As S~IOWII in Fig. 3, tlle inlet ports 42 are also directed
obliquely to a radial ray extending from the longitudillal
axis 26 by an angle o~ of 5 to 40, preferably 15 to 30.
T~lis arrangement of intersecting flows provides not only
direct mixing of the fuel and air inlet flows but also im-
parts rotary or vortex motion of t~le fuel-air mixture form-
ed in tlle space 49. This vortex motion originati~lg in the
space 49 con~ pR with downstream flow out of the central
port 10 and into t~le coirbustion chamber 16. As can be seen
from Fig. 3, one Inlet port 42 is provided for eac~ llet
port ~7. The number of first and second inlet ports 42, 47
respectively is variable, preferably 6 to 14, more prefer-
ably 10 to 12 set:s of ports are provided. To acllieve best
fuel-air mixture and atomization, t~le ports 42 and 47 are
arranged to intersect at an angle of about 60 to 90,
wllere an angle in t~le range of 80 to 90 is most pref-
erred .
Again ~referring to Fig. 1, the central port 10 and the
first and second pluralities of inlet ports 42, 47 are
.,
8- 21817~8
provided in a single no~zle piece 50 This nozzle piece 50
is fitted, for example, by threaded connection, to tlle
dowllstream end of a jet body 36. Tlle jet body is mounted at
an upstream end (not shown) in a manner that it can be
5 axially displaced along the longitudinal axis 26. As men-
tioned above, the outer surface 20 of the jet body is sur-
rounded by the inner surface 22: of the axially displaceable
annular mout~l piece 3~ to form the first annular air inlet
24 .
T~le axial displacement of the jet body 36 allows adjustlnent
-of tlle no~zle 50 Wit~l respect to the combustion wall 12.
This feature allows adj~stment of the vortex flow out of
t~le port 10, depending on the type of fuel being burned and
15 in conjunction t~lerewith the amount and velocity of primary
and secondary air flows. It is particularly preferred tllat
tile j et body be adjusted such that the central port 10 is
located sliglltly upstream of the combustion wall 12. Fur-
t~le~more, for burning heating oil, it is preferred t~lat the
20 central port 10 of t~le nozzle piece 50 be disposed upstream
of tlle end extension of the annular mouth piece 34.
Preferably, t~le fuel burner of the present invention is
operated by supplying fuel, preferably oil, t~lroug}l ~lle
25 second inlet ports 47 provided in common fluid
communication with an upstream source of fuel (not shown in
Fig. 1). In t~lis case, t~le ~irst inlet ports 42 are pro~-
ided in common fluid communication via passage 44 wit~l a
preferably variable source of compressed air.
Alternatively, fuel can be injected in the first inlet
ports 42 w~lile compressed air is injected i~l the first
inlet ports 47.
.
218~7~
With tlle de~ined struct~ral arrangement, t~le primary air
exiting from t~le annular port 24 envelopes t~le vortex flow
of fuel-air mixture exi~ing from the space 49. This spray
cone or expanding cone is then almost immediately inter-
S sected by t~le converging cone of secondary air whicllprovides further mixing and secondary combustion further
illtO t~le combustion chamber.
~11 of tlle f eatures disclosed in the present papers are
10 claimed as being essential to t~le invention to t~le extent
to w~lich t~ley are novel over the prior art eitller individ-
ually or in combination.
