Technical field
[0001] The present invention relates to liquid fuel burners.
[0002] As is well recognized in the industry, there has been a need to develop and to provide
a fuel burning system which is capable of burning a liquid fuel in a very efficient
manner with little or no smoke, and with minimal pollution to the atmosphere.
[0003] In the case of existing residential oil burners, the burner must operate with low
smoke emissions to prevent sooting of the heat exchanger and the objectionable pollution
of residential neighborhoods. The result is that large amounts of excess air must
be introduced in the present residential combustion process to assure that the burner
operates at acceptable smoke levels.
[0004] It is well known that the performance of the high pressure oil burner that is used
almost exclusively in residential heating applications today will vary dramatically
from one furnace or boiler design to the next. This is because the high pressure nozzle
does a poor job of atomizing the fuel. These nozzles produce a substantial number
of large droplets which impinge upon the walls of the combustion chamber and bum slowly.
The speed at which these particles finally vaporize and burn depends upon the size,
shape, and residual heat within the furnace or boiler's combustion chamber. It can
be said then that the combustion chamber within the furnace or boiler serves as a
receptacle to capture large droplets of fuel and as an after-burning device to burn
these large droplets of fuel. Indeed, if the existing high pressure oil burner were
capable of atomizing fuel oil to a high degree, the heat exchanger could be coupled
directly to the burner and there would be no need for a hot combustion chamber or
firebox to complete the combustion process.
[0005] In many instances, the conventional oil burner may be 2-3 times larger than is necessary
to provide adequate space heating. This is the case when the same burner is required
to provide heat for hot water in addition to heat for home comfort. When outside temperatures
are low, and hot water demands are high, a high pressure burner in this type of system
must be able to satisfy both requirements. This maximum heat load is what normally
determines the firing rate of the burner. However, when the demand for heat is low,
as in the spring and fall months and hot water demands are at a minimum, as would
be the case at night, the burner will still operate at the same firing rate as it
does when heating and hot water demands are high. The only difference is that when
the heating requirements are low, the burner will stay on for a very short period
of time. As is well known, this mode of operation is very inefficient. During the
short "on" cycle, the burner cannot achieve smokeless operation and reasonable efficiency
before the thermostat cuts it off. During the "off' cycle, the residual heat in the
furnace is dissipated to the atmosphere and this contributes to increased heat loss.
During the off cycle, there is also a loss of heat within the house as the warm air
escapes through the furnace stack. From this description it can be appreciated that
the most economical domestic oil burner system would be one in which the burner operates
continuously with the ability to vary its output to satisfy the fluctuating heat requirements
within the household. In this way, there can be no inefficiencies associated with
repeated startup and shutdown. A quick calculation will show that the added electrical
cost for continuous burner operation is very minimal compared with the fuel savings
that can be realized.
Background art
[0006] An innovative approach to fuel burners is illustrated in U.S. Patent No. 3,425,058,
issued January 28, 1969, to Robert S. Babington. The burner therein disclosed represents
an adaptation of the liquid atomization principles disclosed in U.S. Patents 3,421,699
and 3,421,692, issued January 14, 1969, to the same named inventor and his co-inventors
in developing the apparatus and method shown in these patents.
[0007] In brief, the principle involved in the aforementioned patents is that of preparing
a liquid for spraying by causing it to spread out in a thin film over the exterior
surface of a hollow plenum chamber which contains at least one orifice. When gas is
introduced into the interior of the plenum, it escapes through the aperture and thereby
creates a very uniform spray of small liquid particles.
[0008] By varying the number of apertures, the configuration of the apertures, the shape
and characteristics of the surface, the velocity and amount of liquid supplied to
the surface, and by controlling the gas pressure within the plenum, the quantity and
quality of the resultant spray can be optimized to suit the particular burner application.
[0009] It is this basic principle, described above, that was utilized in the development
of the burner disclosed in said Patent 3,425,058.
[0010] In the above-mentioned patent, the burner is so simple that it might even be called
a fuel atomizing subsystem for a burner rather than a complete burner. Indeed, from
this very simple burner or subassembly evolved the more sophisticated and complete
burner described in the present invention. In the earlier said Patent 3,425,058, the
burner is comprised of a simple atomizing chamber having a cover thereover, the cover
being provided with a spray discharge port to discharge the atomized fuel in a generally
vertical direction. Disposed within the atomizing chamber is a hollow plenum type
atomizer that is in communication with an outside source of pressurized air. Liquid
is introduced into the atomizing chamber so as to flow over the exterior surface of
the atomizing plenum. Excess fuel that is not sprayed off flows downwardly into a
drain where it is recirculated via a pump means to the liquid supply line. The atomizing
plenum is provided with a small aperture centrally located beneath the opening in
the cover, and the air exiting therefrom creates a fine mist which is discharged upwardly
and out of the atomizing chamber for combustion external to the system. Means comprising
a series of regulatable apertures are also provided in the atomizing chamber such
that aspirated air can be drawn into said chamber or burner and mingled with the spray
as it discharges from the opening in the top cover.
[0011] From this very simple version of a fuel burner was derived more sophisticated equipment,
such as that shown and discussed in an article in the January 1976 issue of Popular
Science entitled "Clog-Proof Super Spray Oil Burner". As noted in the article, one
development that evolved was the use of two atomizing plenums arranged to discharge
the atomized liquids towards each other to create a more stable flame and a good place
to initiate ignition.
[0012] Other arrangements of opposed spray heads are also suggested in U.S. patents by Babington,
namely Patent 3,751,210 dated August 1973, and Patent 3,864,326 dated February 1975.
[0013] All of the above noted developmental work based on the utilization of the "Babington"
principle proved conclusively that the system was perfectly capable of use in a fuel
burning system and that, if properly designed, such a system has the potential of
evolving into a commercial, practical, highly efficient fuel burner which can be used
for domestic heating furnaces.
Description of the invention
[0014] One object of the invention is to produce a burner that performs with high efficiency
regardless of the combustion chamber that it is placed into and therefore ideally
suited as a retrofit or replacement burner for existing furnaces.
[0015] A further object of this invention is to produce an oil burner wherein combustion
is essentially completed within the flame tube of the burner.
[0016] Still another object of this invention is to produce an oil burner where combustion
air is supplied to control the burning rate and temperature and hence objectionably
high nitrous oxide emissions.
[0017] The burner of this invention comprises a plurality of atomisers for discharging atomised
fuel into a flame tube for substantially complete combustion in the tube per se. To
ensure this combustion the present invention provides an atomising chamber separated
from the flame tube by a dividing wall having openings through which are directed
the streams of fuel. To ensure substantially complete combustion, thorough mixing
of the fuel and air must take place within the tube. By the present invention, this
can be done basically in two ways or a combination of both. One either pressurises
the atomizing chamber so that a mixture of atomized fuel, low velocity air, and air
under pressure passes through the openings in the dividing wall, and/or one provides
air introduction means in the flame tube downstream of its inlet end to introduce
air into the flame tube with a tangential component to produce in the flame tube a
single tangential vortex.
Brief description of the drawings
[0018] Reference is now made to the appended drawings and the detailed description which
follows, showing two preferred modes of practicing the invention:
Figures 1A and 1B are schematic views of a typical heating furnace or firebox and
showing the utility of the present invention as compared to the usual prior art apparatus;
Fig. 2 is a sectional plan view showing details of a flame tube assembly for a liquid
fuel burner in accordance with the present invention;
Fig. 3 is a sectional view of a fuel atomizing system in which an improved spray discharge
horn is utilized.
Best mode for carrying out the invention
[0019] Turning now to Figs. 1A and 1 B, it will be noted that in the prior art the atomizing
nozzles are located at the end of the blast tube. Consequently, the nozzle is subjected
to high temperatures, and as such is subject to varnish depositions and clogging.
[0020] In contrast, utilizing applicant's improved fuel burning system, the atomizing plenums
are located well upstream from the end of the blast tube and as such are sheltered
from the radiant and convective heat of the firebox and the associated problems of
fuel cracking and varnishing.
[0021] These characteristics of total independence of furnace design and furnace temperature
makes the present invention ideal as a replacement or retrofit burner. This non-dependence
of furnace temperature also means that the present burner will achieve smokeless operation
the instant ignition occurs and before the combustion chamber becomes hot. The typical
conventional high pressure burner takes several minutes for the smoke level to drop
to acceptable levels after ignition has occurred.
[0022] As shown in Fig. 2, the improved fuel burning assembly comprises a blast tube 1 which
is essentially an elongated open-ended pipe. Disposed within blast tube 1 is flame
tube 3 which is maintained concentric with respect to the blast tube so as to define
an annular air passage therebetween. Flame tube 3 is maintained concentric to blast
tube 1 by positioning its one end against a circumferential shoulder 67 which can
include set pins or screws (not shown) and at its other end by ring 7. Other means
can be used to maintain the flame tube concentrically within the blast tube 1. The
flame tube 3 is open at both ends; one end 9 thereof, which may be termed the hot
end, faces toward the interior of the firebox of the furnace or the like. The other
end which may be called the cool end, is attached to atomizing chamber 52 by means
of a slip fit over the aforementioned shoulder 67. Further upstream of atomizing chamber
52 and not shown, provisions may also be made to house the auxiliary burner equipment
such as the drive motor, air atomizing compressor, combustion air blower, fuel recirculation
system and the electronic burner controls, if desired.
[0023] The open end 9 of the flame tube 3 is provided with a pair of cutouts 13, 13', the
function of which will become apparent subsequently. Similarly the flame tube is provided
with a further pair of apertures 12, 12' located approximately midway of its length.
These apertures (12, 12') are disposed at 90° relative to the cutouts 13, 13', but
flame tube 3 may be rotated 90° to alter the flame pattern leaving the burner.
[0024] In addition, the flame tube of Fig. 2 is provided with a plurality of centrifugal
swirl shutters or louvers 50. One convenient configuration employs 4 louvers, each
being spaced about one-quarter of the circumference of the flame tube from the adjacent
louvers. Other configurations and amounts of louvers can be employed if desired. The
louvers are placed upstream from the apertures 12, 12' and preferably axially about
midway between apertures 12, 12' and fire wall 57. The louvers provide for a curtain
of swirling air along the flame tube wall. The swirling is confined as will be discussed
hereinbelow in view of the interrelationship of the louvers with the apertures 12,
12' and the cutouts 13, 13'. Tyically the apertures 50, 12, 12', 13 and 13' are about
0.2-0.4 square inch in cross-sectional area for a typical burner with a variable firing
rate of from about .75 to about 2.3 liters/hr.
[0025] The cylindrical flame tube 3 is provided at its opposite end 11 with a pair of spray
discharge horns 17 and 17', communicating with a common atomizing chamber 52. Certain
burner operating conditions do not require the use of spray discharge horns 17 and
17' and in such cases, a simple opening in said atomizing chamber 52 would be provided
instead.
[0026] More particularly, in certain burner variations discharge horn 17' may be a simple
cylindrical section or even a truncated cone diverging outwardly towards the flame
tube. The size and shape of spray discharge horn 17 will depend upon the aerodynamic
conditions surrounding atomizing chamber 52, as dictated by the upstream blower pressure
and the downstream static and dynamic pressure within the flame tube. In any event,
the spray discharge horns are designed to control the size of the liquid fuel spray
particles and/or to prevent the flame within the flame tube from propagating upstream
into the atomizing chamber. These features will be explained further in a subsequent
discussion of Fig. 3 which shows an improved discharge horn configuration. In certain
applications of the present invention where there is sufficient airflow and pressure
available from the auxiliary compressor and combustion air blower, the upstream flame
propagation may be prevented, and the liquid particle size optimized, without the
need for spray discharge horn 17'. This is done by controlling the conditions within
atomizing chamber 52 and involves the interrelationship of variables such as the size
and shape of atomizer 26'; the size and shape of discharge orifice 29'; the pressure
supplied to the interior of atomizer 26' via tube 27'; the internal diameter of feed
tube 23'; the spacing and relative fore and aft positioning of atomizer 26' with respect
to lower end 36' of feed tube 23'; the spacing between discharge orifice 29' and the
forward face 51 of atomizing chamber 52; the quantity of fuel supplied through feed
tube 23'; the size of blower inlet ports 33', and the velocity and quantity of air
entering atomizing chamber 52 through blower inlet ports 33'. In cases where the spray
discharge horns 17 and 17' are not required, they are simply removed with the result
that the spray particles emanating from atomizers 26 and 26' are discharged directly
into flame tube 3.
[0027] The following parameters represent some typical values for a burner with a variable
firing rate from about 0.75 to about 2.25 liters/hr. A typical atomizer is a sphere
or bullet shape between about 1/6 to about 25 nim. outside diameter. The cross-sectional
area of the discharge orifice 29' typically is about .065 mm
2 to about 0.2 mm
2. The pressure supplied to the interior of atomizer 26' via tube 27' is typically
about 140 grams/cm
2 to about 1400 grams/cm
2. The spacing between discharge orifice 29' and the forward face 51 of atomizing chamber
52 can be from 0 to about 25 mm.
'The spacing between lower end 36' of liquid feed tube 23' and the uppermost surface
of atomizer 26' is typically about 3 mm. to about 9 mm. The typical dimensions for
blower inlet ports 33' are about 3-9 mm. diameter. Typical internal diameters of feed
tube 23' are about 1.6 mm. to about 6.5 mm. The length of spray discharge horn 17'
when present can be up to about 38 mm. and have an exit diameter between about 9 mm.
and 25 mm.
[0028] Spray discharge horns 17 and 17' are supported upon a solid wall 51 which is shown
as being generally straight and transverse to the flame tube. Also supported upon
the solid wall 51 is an air blast tube 53 located within and concentric with the central
axis of the atomizing chamber 52. The air blast tube 53 passes through and is also
supported by the back wall 54 of atomizing chamber 52. The rear wall 54 of the atomizing
chamber 52 is provided with an aperture 61' to admit air into the air blast tube 53.
[0029] The air blast tube 53 can include a pair of apertures 56, 56' (e.g.-typically having
a diameter between about 3-12 mm.) leading to the atomizing chamber 52. These apertures
provide for a portion of the blower air entering the central air blast tube to be
entrained into the atomizing chamber 52 where it commingles with the fuel spray and
is discharged into the flame tube through spray discharge horns 17 and 17'. Should
apertures 56 and 56' be insufficient to provide chamber 52 with the needed air to
supply the aspiration needs of plenums 26 and 26', or if it is desired to further
raise the static pressure within common chamber 52, then blower air inlet ports 66
and 66' of similar or smaller cross-sectional area to 56, 56' may be provided in wall
54. Consequently, by sizing blower air inlet ports 66 and 66' in conjunction with
apertures 56 and 56', chamber 52 may be operated at any desired pressure. The forward
wall 51 of atomizing chamber 52 is provided with a relatively large central aperture
55 passing through the wall 51. This aperture 55 is the same size as the inside diameter
of air blast tube 52 which is about 6 mm. to about 38 mm. so that blower air can pass
directly through air blast tube 53, and enter the flame tube via aperture 55 in wall
51. Spaced slightly downstream such as about 3 mm. to about 12 mm. from the forward
wall 51 of the atomizing chamber and parallel thereto, is a foraminous or perforated
fire wall 57 which is shown as being generally planar and containing apertures therein.
The perforated fire wall 57 is provided with a relatively large central aperture 59
passing through the wall 57. The large central opening 59 in the perforated fire wall
57 is preferably smaller than the inside diameter of the central blast tube and hence
the opening 55 in wall 51. As a result, a small amount of air is forced out radially
between the forward wall 51 of the atomizing chamber 52 and the perforated fire wall.
This air bleeds through the perforated fire wall and into the flame tube to keep the
fire within the flame tube from impinging on the fire wall.
[0030] Projecting through rear wall 54 and front wall 51 of the atomizing chamber and further
extending into the flame tube through a pair of openings in fire wall 57 is a pair
of electrodes 19 and 21. Said electrodes are encased in porcelain jackets 68 and 69
to shield said electrodes from fuel spray as they pass through atomizing chamber 52.
The spark gap 70 between electrodes 19 and 21 is located within the flame tube and
on the outer periphery of the spray plume issuing from atomizer 26.
[0031] As shown in Fig. 2, the chamber 52 may be provided with discharge cones 17 -and 17'
which discharge atomized fuel inwardly into the flame tube 3.
[0032] Both of the hollow atomizing plenum chambers 26, 26' have a smooth outer surface
and are disposed within the same atomizing chamber 52. Plenum 26' is supported on
the rear wall 54 of chamber 52 and plenum 26 is interconnected via conduit 27' from
plenum 26'. Use of a common chamber assures that the static pressure surrounding atomizing
plenum 26 is essentially the same as that surrounding plenum 26'. Plenums 26 and 26'
are supplied with air under pressure through conduits 27 and 27' respectively. As
shown in Fig. 2, the air is supplied to conduits 27 and 27' from the same source via
conduits 60 and 61 respectively. Of course, separate sources of air can be employed
if desired.
[0033] Each atomizing plenum 26 and 26' is provided with at least one small aperture 29
and 29' which is located so as to discharge air and fuel spray directly toward its
associated discharge horn 17 and 17'. There need only be one common drain located
at the low point in atomizing chamber 52.
[0034] A pair of fuel supply conduits 23 and 23' are preferably connected to a source of
liquid fuel by means of a pump, whereby the fuel may be pumped through these conduits
and deposited on the convex surfaces of atomizing plenums 26 and 26' respectively.
A single drain conduit (not shown in Fig. 2) is connected to the fuel supply system
so that liquid which is not atomized within common atomizing chamber 52 can be returned
to the fuel system not shown and recirculated back to fuel supply conduits 23 and
23'. The operation of the fuel atomizing and combustion system is as follows.
[0035] Liquid fuel is introduced into the system by the conduits 23, 23'. The liquid fuel
flows over atomizing plenums 26, 26' and a portion thereof is atomized by air under
pressure which is introduced into each plenum through conduits 27 and 27'. Liquid
which is not atomized flows to the bottom of the common atomizing chamber 52 and is
withdrawn therefrom by a drain conduit for recirculation in the fuel supply system.
[0036] As described above, the atomization process utilizes the basic "Babington" principle
disclosed in prior mentioned U.S. Patents 3,421,699 and 3,421,692.
[0037] The burner configuration illustrated in Fig. 2 operates at such a high combustion
efficiency that fuel-gas CO
2 levels of 15%, which are approximately the maximum level, have been achieved at zero
smoke. This value is just below the theoretically obtainable when the precise amount
of air is mixed with the hydrocarbon fuel. This is in contrast to the average conventional
home oil burner that operates at C0
2 levels of 8% even when the burner firing rate is matched to the furnace capacity.
[0038] The air blast tube 53 directs air along the central axis of the single atomizing
chamber 52 and along the central axis of the flame tube 3. A portion of the blower
air entering the air blast tube 53 is preferably entrained or forced into the atomizing
chamber 52 via openings 56 and 56' where it commingles with the fuel spray and is
discharged into the flame tube 3 via spray discharge horns 17 and 17'. The atomizers
may draw the air into the chamber 52 via apertures 56 and 56' by the low pressure
area created at the orifices of said atomizing plenums, or under certain operation
conditions pressurized air may also be forced into atomizing chamber 52 through apertures
56 and 56'.
[0039] As stated earlier, common chamber 52 may also be fitted with blower air pressurization
ports 66 and 66' so that common chamber 52 may be operated at still a more elevated
static pressure if so desired. Such pressurization would more likely be employed at
high firing rates and where it is desirous to mix as much air with the atomized spray
as possible before discharging the mixture into the flame tube.
[0040] The use of one common atomizing chamber to contain the atomizing plenums instead
of a plurality of atomizing chambers assures that the ambient pressure surrounding
each atomizing plenum will be essentially the same. With a common atomizing chamber
the local air velocity around each atomizer is also reduced because of the larger
volume inside common chamber 52. Thus in chamber 52 it is further assured that high
air velocities will not disturb the film of liquid flowing over atomizers 26 and 26'.
[0041] Since the large central opening in the perforated wall is smaller than the inside
diameter of the central air blast tube 53, a small amount of air is directed or forced
radially outwardly between the forward face of the atomizing chamber and the perforated
fire wall. The perforations in the fire wall are so numbered and sized that a very
soft flow of air passes through this wall. This air bleeds through the perforated
fire wall and into the flame tube, thereby keeping or holding the flame off the fire
wall, and insulating the relatively cool surface of the front face of the atomizing
chamber from the hot environment on the downstream side of the fire wall. Without
the perforated fire wall the condition of relatively cool fuel on the inside of the
atomizing chamber, and a hot fire on the downstream side of the atomizing chamber
would predispose the forward wall of the atomizing chamber to soot buildup on the
flame tube side. In addition, the use of generally straight walls minimizes the tendency
for soot buildup.
[0042] The use of a substantially planar face fire wall 57 permits the minimum included
angle where sprays meet to be quite small. The preferred minimum included angle is
about 5°. Excellent results have been achieved with an angle of about 27°.
[0043] The centrifugal swirl shutters or louvers 50 promote rapid mixing of combustion air
and fuel spray to prevent soot buildup on the flame tube 3. The air which passes into
the flame tube through the centrifugal swirl shutters provides a curtain of swirling
air along the flame tube wall. This insulates the flame tube wall from direct flame
impingement and prevents hot spots and flame erosion problems. The curtain of swirling
air is heaviest in the upstream vicinity of the flame tube where it enters through
the louvers. When the swirling air encounters the transverse air blasts about midway
along the flame tube from apertures 12, 12', and again at the discharge lip of the
flame tube from cutouts 13, 13', the swirling motion is substantially destroyed. This
is important to assure that the swirling air is mixed with the vaporized and burning
fuel before it exits flame tube 3.
[0044] The unique configuration of the flame tube within a blast tube provides a unique
heat exchanger in which combustion air for staging purposes passes through the annular
area between the flame tube and the blast tube. In traversing this route, the combustion
air picks up heat from the inner hot walls of the flame tube. This hot air, as it
is delivered to the interior of the flame tube at the aforementioned staging locations
helps to promote rapid vaporization of the atomized fuel to complete the combustion
process downstream in the flame tube. The staging of combustion air in this manner
allows the temperature within the flame tube to be maintained at the desired level
to keep nitrous oxide emissions to a minimum.
[0045] Still another advantage of the manner in which combustion air is staged is to produce
a flame which, when emitted from the burner, is short and bushy. This is achieved
by introducing staged air in a nonsymmetrical manner which is contrary to the fuel/air
mixing technique used in conventional residential type oil burners. For example, at
the first combustion air staging location, downstream from the spray impingement site,
two air blasts 12, 12' may be introduced perpendicular to the long axis of the blast
tube, at three o'clock and nine o'clock locations. By subjecting the flame within
the flame tube to a nonsymmetrical air blast of this type, the flame is caused to
squirt out and fill the flame tube at the six o'clock and twelve o'clock positions.
Furthermore, the low static pressure within the air blasts at the three and nine o'clock
positions causes the flame to wrap around the air blasts and thus produce a shorter
and more compact flame which fills the entire flame tube.
[0046] In the second combustion air staging location, two air blasts are introduced at the
lip of the blast tube but this time the air blasts are introduced at the twelve o'clock
and six o'clock positions. This causes the flame to spread out in the three o'clock
and nine o'clock position as it leaves the burner blast tube and enters the combustion
chamber.
[0047] A short bushy flame of this type is ideal for a retrofit or replacement burner, because
it is suited for use in any type of combustion chamber. This is in contrast to a long
thin flame which would impinge upon the back side of many combustion chambers and
cause erosion of the combustion liner. At the same time, the combustion air passing
between the flame tube and the blast tube serves to keep the outer blast tube cool,
thereby preventing heat erosion of the blast tube. In the case of the present invention,
the atomization system is so efficient, and the subsequent fuel/air mixing and vaporization
is likewise carried out in such a highly efficient manner, that the burner does not
require a hot combustion chamber to achieve high combustion performance.
[0048] A fact to be noted is that conventional high pressure nozzles have difficulty operating
at firing rates below approximately 2.6 liter/hr. without encountering a high incidence
of clogging. In the present burner, there is essentially no minimum firing rate that
can be attained; a prototype burner has been operated at a firing rate of less than
0.38 liters/hr. This means that each individual atomizer is operating at less than
0.19 liters/hr. Further, it is not necessary, in the present burner, that both atomizers
be generating the same amount of fuel spray for the burner to operate efficiently.
For example, one atomizer may have a firing rate of 0.22 liters/hr. while the other
has a firing rate of 0.15 liters/hr. A burner of this type will operate just as efficiently
as one in which each atomizer is delivering a spray rate of 0.18 liters/hr. This low
firing rate capability of the present invention is very important in light of the
present energy crisis because homes in the future will be built with better insulation
and the trend is towards low firing burners that can provide highly efficient operation.
[0049] The spray discharge horn 17' served two purposes. Horn 17' controls the mass median
diameter of the spray entering flame tube 3 and also prevents the flame within flame
tube 3 from propagating upstream and into atomizing chamber 15. The spray particle
size can be optimized by adjusting the geometry of horn 17' with respect to its length,
exit diameter and conical angle. Said horn can be sized such that the spray issuing
forth from orifice 29' is discharged into flame tube 3 unrestricted by horn 17', or
said horn may be designed to restrict a portion of the spray emanating from 29'. In
this latter case, the inner walls of said horn serve to skim off the larger spray
particles on the outer periphery of the spray plume. These captured fuel particles
simply flow back into atomizing chamber 15 along the inclined inner walls of said
spray discharge horn 17'. This technique works well when the skimming required is
minimal, and when the velocity of the commingled air and fuel particles passing through
said horn is low. However, when it is desired to restrict a substantial amount of
the spray to further reduce particle size, or when velocities within discharge horn
17' are high, the discharge horn assembly shown in Fig. 3 is more useful. This high
velocity discharge horn assembly 20' is comprised on an inner shroud 17' and an outer
shroud 22. As shown in Fig. 3 the downstream ends of these shrouds are preferably
in the same plane. However, in some cases, depending upon the static pressure, combustion
air velocity, and local eddies within flame tube 3, outer shroud 22 may be somewhat
longer or shorter than inner shroud 17' to promote better drainback and/or to eliminate
soot buildup between said shrouds or around the entire configuration 20'.
[0050] In operation, the high velocity discharge horn assembly 20' shown in Fig. 3 skims
off a portion of the fuel spray originating from orifice 29'.
[0051] The relatively high velocity of the spray passing through inner shroud 17' causes
impinging fuel to run along the inner walls of shroud 17' towards the flame tube.
This raw fuel is prevented from spilling over into the flame tube by means of the
outer shroud 22. Said raw fuel upon reaching the discharge lip of the inner shroud
17' runs back between said inner shroud and said outer shroud 22, mostly along the
outer surface of the inner shroud 17, and back towards the forward wall 28 of the
atomizing chamber 15. This excess or run-off fuel then drains back into chamber 15
via small drain tube 72. During burner operation, drain tube 72 which has an I.D.
of approximately 1.6-3.2 mm. becomes filled with fuel and acts as a trap to prevent
the back flow of combustion products into the atomizing chamber.
[0052] The other purpose of high velocity discharge horn assembly 20' is to prevent burn-back
in the atomizing chamber. Essentially the assembly acts as an ejector which is sized
such that the fuel/air velocity exiting from said inner shroud 17' is at least as
great as the flame speed of the fuel burning within flame tube 3. This means that
the flame within the flame tube cannot propagate upstream and into atomizing chamber
15'.
[0053] In cases where the velocity of commingled liquid spray and air exiting from discharge
horn assembly 20' is very high so as to cause flame instability or a fluctuating flame
front within the flame tube 3, then flame holder 71 may be provided. Said flame holder
is in the form of a simple ring or washer having a large central opening 63, said
opening being sized slightly larger than that of the spray plume diameter at that
point. This allows the fuel spray to pass unimpeded through said opening 63 without
wetting the walls of said flame holder 71. The turbulence and subsequent low static
pressure that is created around flame holder 71 when the spray passes through it,
causes the flame to seat or attach itself to the downstream face of flame holder 71.
In Fig. 3 said flame holder 71 is supported from outer shroud 22 by two small rod
like appendages 62. It is desirable that these rods 62 be small in cross-section so
that flame holder 71 takes on the appearance of being suspended in space approximately
3.2-3.8 mm. downstream of the exit of inner shroud 17'. The exact location of flame
holder 71 will depend upon the relative velocity between the flame speed and the fuel/air
mixture leaving shroud 17'.
1. A liquid fuel burner characterised in that it comprises the combination of:
a flame tube (3) having an inlet end and an outlet end,
an atomizing chamber (52) communicating with said inlet end of said flame tube and
enclosing fuel atomizing means (26, 26') for discharging atomized fuel into said flame
tube (3) through openings in a dividing wall (51) separating said flame tube (3) from
said atomizing chamber (52),
said atomizing means (26, 26') comprising a plurality of hollow plenum chambers each
having a smooth outer surface and each defining therein a small through aperture (29,
29'), a means (23, 23') for producing a flow of fuel in a thin film over each said
through aperture and a means (27, 27') for introducing air under pressure into each
said plenum chamber (26, 26') to rupture said film at said aperture (29, 29'),
means (54) for supporting said plenum chambers (26, 26') in said atomizing chamber
(52) in a manner to cause the plurality of directional streams of atomized fuel issuing
therefrom to be directed through respective ones of said openings in said dividing
wall (51) into said flame tube (3) in directions extending along the central axis
of said flame tube for combustion of substantially all said atomized fuel within said
flame tube (3),
means (56, 56'; 66, 66') for introducing air into said atomizing chamber (52) to thereby
cause low velocity air to issue through said openings in said dividing wall along
with said streams of atomized fuel and said pressurized air issuing from each said
plenum chamber (26,26').
means (19, 21) for igniting the atomized fuel in said flame tube (3) downstream of
its said inlet end,
first means (50) for introducing air into said flame tube (3) adjacent but downstream
of its inlet end with a tangential component to produce in said flame tube (3) a single
tangential vortex to promote the admixing of air with the atomized fuel and to maintain
the flame spaced from the flame tube's inner surface adjacent its inlet end,
and second means (12, 13) for introducing air into said flame tube (3) at at least
one location downstream of the location of air introduction by said first means (50)
and downstream of the point of ignition of the fuel-air mixture by said ignition means
(19, 21) with a velocity and direction to impede the tangential vortex generated by
said first means so as to permit the flame to expand to the flame tube wall and to
permit substantially complete combustion within the confines of the flame tube (3).
2. The burner of Claim 1 in which a foraminous radiation shield (57) is supported
adjacent to but spaced from the side of said dividing wall (51) facing said flame
tube (3).
3. The burner of Claim 2 which further includes a spray discharge cone (17, 17') for
each said plenum chamber (26, 26') each said spray discharge cone (17, 17') being
truncated with its larger end adjacent the through aperture (29, 29') of the associated
plenum chamber (26, 26') and extending through a respective opening in said dividing
wall (51) and said radiation shield (57).
4. The burner of Claim 2 or 3 in which both said shield (57) and said dividing wall
(51) define a central aperture (55, 59) for producing a flow of air from a source
of pressurized air along the central axis of said flame tube (3).
5. The burner of Claim 4 which further includes a central tube (53) extending from
said air source and communicating with aperture (55) in dividing wall (51) and aperture
(59) in shield (57).
6. The burner of any preceding Claim in which said first means (50) comprises a plurality
of louvers formed in said flame tube wall.
7. The burner of any preceding Claim in which said second means comprises a plurality
of apertures (12) in said flame tube (3) disposed substantially at the mid-length
thereof.
8. The burner of any of Claims 1 to 6 in which said second means comprises a plurality
of apertures (13) in said flame tube (3) substantially at its outlet end.
9. The burner of any preceding Claim in which said second means (12, 13) comprises
a first plurality of apertures (12) in said flame tube (3) substantially at the mid-length
thereof and a second plurality of apertures (13) in said flame tube (3) substantially
at its said outlet end.
10. The burner of any preceding Claim which includes means (56, 56'; 66, 66') enabling
pressurizing of said atomizing chamber (52) with a pressure above atmospheric.
11. The burner of Claim 10 which further includes air channel means for conveying
air via said first and second means (50; 12, 13) to the interior of said flame tube
(3).
12. The burner of Claim 11 in which said air channel means includes a tube (1) of
larger diameter than, and surrounding, said flame tube (3) to define an annular channel.
13. A liquid fuel burner characterised in that it comprises the following combination
of feature:-
a flame tube (3) having an inlet end and an outlet end,
an atomizing chamber (52) communicating with said inlet end of said flame tube (3)
and enclosing fuel atomizing means (26, 26') for discharging atomized fuel into said
flame tube (3) through openings in a dividing wall (51) separating said flame tube
(3) from said atomizing chamber (52),
said atomizing means (26, 26') comprising a plurality of hollow plenum chambers each
having a smooth outer surface and each defining therein a small through aperture (29,
29'), means (23, 23') for producing a flow of fuel in a thin film over each said through
aperture and means (27, 27') for introducing air under pressure into each said plenum
chamber (26, 26') to rupture said film at said aperture (29, 29'),
means (54) for supporting said plenum chambers (26, 26') in said atomizing chamber
(52) in a manner to cause the plurality of directional streams of atomized fuel issuing
therefrom together with said air under pressure which passes through said apertures
(29, 29') in said plenum chambers (26, 26') to be directed through respective ones
of said openings in said dividing wall (51) into said flame tube (3) in directions
extending along the central axis of said flame tube (3),
means (56, 56'; 66, 66') for pressurizing said atomizing chamber (52) with above atmospheric
pressure to thereby cause low velocity air to also issue through said openings in
said dividing wall (51) along with said streams of atomized fuel,
means (19, 21) for igniting the atomized fuel in said flame tube (3) downstream of
its said inlet end,
and means (12, 13) for introducing air into said flame tube (3) at at least one location
along its length for admixing with the atomized fuel.
1. Flüssigkraftstoffbrenner, gekennzeichnet durch die Kombination von:
einem Flammrohr (3), das ein Einlaßende und ein Auslaßende aufweist,
einer Atomisierkammer (52), welche in Verbindung steht mit dem Einlaßende des Flammrohres
und welche Kraftstoffatomisiermittel (26, 26') umschließt zur Verteilung atomisierten
Kraftstoffs in das Flammrohr (3) durch Öffnungen in einer Trennwand (51), die das
Flammrohr (3) von der Atomisierkammer (52) trennt,
wobei diese Atomisiermittel (26, 26') aus einer Vielzahl von hohlen Luftkammern bestehen,
von denen jede eine glatte äußere Oberfläche aufweist, und jede eine kleine Durchgangsbohrung
(29, 29') darin definiert, mit Mitteln (23, 23') zur Erzeugung eines Kraftstoffflusses
als dünner Film über jeder dieser Durchgangsbohrungen und mit Mitteln (27, 27') zur
Einführung von Druckluft in dieser Luftkammern (26, 26') zum Zerreissen dieses Films
an dieser Bohrung (29, 29'),
Mitteln (54) zum Tragen dieser Luftkammern (26, 26') in dieser Atomisierkammer (52)
in der Weise, daß eine Mehrzahl von ausgerichteten Strömen von atomisiertem Kraftstoff
von dieser Kammer veranlasst wird, durch jeweils eine dieser Öffnungen in dieser Trennwand
(51) in des Flammrohr (3) auszutreten in Richtungen längs der Mittenachse dieses Flammrohres
zur im wesentlichen vollständigen Verbrennung dieses atomisierten Kraftstoffes innerhalb
dieses Flammrohres (3),
Mitteln (56, 56', 66, 66') zur Einführung von Luft in diese Atomisierkammer (52) zur
Erzeugung eines Luftstromes geringer Geschwindigkeit durch diese Öffnungen in dieser
Trennwand zusammen mit den Strömen von atomisierten Kraftstoff und dieser Druckluft,
wie sie von jeder dieser Luftkammern (26, 26') abgehen,
Mitteln (19, 21) zur Zündung des atomisierten Kraftstoffes im Flammrohr (3) stromabwärts
von seinem Einlaßende,
ersten Mittel (50) zur Einführung von Luft in dieses Flammrohr (3) nahe, jedoch stromabwärts
von seinem Einlaßende mit einer Tangentialkomponente zur Erzeugung eines einzigen
tangentialen Wirbels im Flammrohr (3) zur Begünstigung des Vermischens von Luft mit
dem atomisierten Kraftstoff und zum Fernhalten der Flamme von der inneren Oberfläche
des Flammrohres im Bereich seines Einlaßendes,
und von zweiten Mitteln (12, 13) zur Einführung von Luft in dieses Flammrohr (3) an
mindestens einer Stelle stromabwärts von der Stelle der Lufteinführung durch die ersten
Mittel (50) und stromabwärts vom Zündpunkt des Kraftstoff-Luftgemisches durch diese
Zündmittel (19, 21) mit einer Geschwindigkeit und einer Richtung daß der durch die
erste Mittel erzeugte tangentiale Wirbel unterdrückt wird, damit es der Flamme möglich
wird, sich zur Wand des Flammrohres hin auszudehnen und um eine im wesentlichen vollständige
Verbrennung innerhalb des Umrisses des Flammrohres (3) zu ermöglichen.
2. Brenner nach Anspruch 1, bei welchem ein löchriges Strahlungsschild (57) nahe,
jedoch im Abstand zu derjenigen Seite dieser Trennwand (51) angeordnet ist, welche
zum Flammrohr (3) hinzeigt.
3. Brenner nach Anspruch 2, der weiterhin umfasst einen Strahlaustrittskonus (17,
17') für jede dieser Luftkammern (26, 26'), wobei jeder Strahlaustrittskonus (17,
17') kegelstumpfförmig mit seinem größeren Ende nahe der Durchgangsbohrung (29, 29')
der zugeordneten Luftkammer (26, 26') angeordnet ist und sich durch entsprechende
Öffnungen in dieser Trennwand (51) und diesem Strahlungsschild (57) erstreckt.
4. Brenner nach Anspruch 2 oder 3 bei welchem sowohl des Schild (57) als auch die
Trennwand (51) eine zentrale Öffnung (55, 59) definieren zur Erzeugung eines Luftstromes
von einer Luftdruckquelle längs der Mittenachse dieses Flammrohres (3).
5. Brenner nach Anspruch 4, welcher weiterhin umfasst ein zentrales Rohr (53), welches
sich von dieser Luftguelle erstreckt und in Verbindung steht mit Offnung (55) in der
Trennwand (51) und Öffnung (59) in Schild (57).
6. Brenner nach einem der vorhergehenden Ansprüche, bei welchem diese ersten Mittel
(50) aus einer Vielzahl von Wirbelklappen, welche in dieser Flammrohrwand gebildet
werden, bestehen.
7. Brenner nach einem der vorhergehenden Ansprüche, bei welchem diese zweite Mittel
auf einer Vielzahl von Öffnungen (12) in diesem Flammrohr (3) bestehen, welche im
wesentlichen in dessen Längsmitte angeordnet sind.
8. Brenner nach einem der Ansprüche 1 bis 6, bei welchem diese zweiten Mittel aus
einer Vielzahl von Öffnungen (13) in diesem Flammrohr (3) im wesentlichen an dessen
Auslaßende bestehen.
9. Brenner nach einem der vorhergehenden Ansprüche, bei welchem diese zweiten Mittel
(12, 13) aus einer ersten Anzahl von Öffnungen (12) in diesem Flammrohr (3) im wesentlichen
in dessen Längsmitte und einer zweiten Anzahl von Öffnungen (13) in diesem Flammrohr
(3) im wesentlichen an dessen Auslaßende bestehen.
10. Brenner nach einem der vorhergehenden Ansprüche, welcher Mittel (56, 56', 66,
66') umfasst zum Unterdrucksetzen dieser Atomisierkammer (52) mit einem Druck oberhalb
Atmosphärendruck.
11. Brenner nach Anspruch 10, welcher weiterhin umfasst Luftkanalmittel zum Leiten
von Luft über die ersten und zweiten Mittel (50, 12, 13) in das Innere des Flammrohres
(3).
12. Brenner nach Anspruch 11, bei welchem diese Luftkanalmittel ein Rohr (2) umfassen
mit einem größeren Durchmesser als das Flammrohr (3), das es umgibt zur Bildung eines
ringförmigen Kanals.
13. Flüssigkraftstoffbrenner, gekennzeichnet, durch die Kombination von:
einem Flammrohr (3), das ein Einlaßende und ein Auslaßende aufweist,
einer Atomisierkammer (52), welche in Verbindung steht mit dem Einlaßende des Flammrohres
und welche Kraftstoffatomisiermittel (26, 26') umschließt zur Verteilung atomisierten
Kraftstoffs in das Flammrohr (3) durch Öffnungen in einer Trennwand (51), die das
Flammrohr (3) von der Atomisierkammer (52) trennt,
wobei diese Atomisiermittel (26, 26') aus einer Vielzahl von hohlen Luftkammern bestehen,
von denen jede eine glatte äußere Oberfläche aufweist und jede eine kleine Durchgangsbohrung
(29, 29') darin definiert, mit Mitteln (23, 23') zur Erzeugung eines Kraftstoffflusses
als dünner Film über jeder dieser Durchgangsbohrungen und mit Mitteln (27, 27') zur
Einführung von Druckluft in jede dieser Luftkammern (26, 26') zum Zerreissen dieses
Films an dieser Bohrung (29, 29'),
Mitteln (54) zum Tragen dieser Luftkammern (26, 26') in dieser Atomisierkammer (52)
in der Weise, daß eine Mehrzahl von ausgerichteten Strömen von atomisiertem Kraftstoff
von dieser Kammer zusammen mit der unter Druck stehenden Luft, die durch diese Bohrungen
(29, 29') in diesen Luftkammern (26, 26') hindurchgeht, veranlasst wird durch jeweils
eine dieser Öffnungen in dieser Trennwand (51) in des Flammrohr (3) auszutreten in
Richtungen längs der Mittenachse dieses Flammrohres,
Mitteln (56, 56', 66, 66') zum Unterdrucksetzen dieser Atomisierkammer (52) mit überatmosphärischem
Druck, um einen Luftstrom geringer Geschwindigkeit zum Ausströmen durch diese Öffnungen
in dieser Trennwand zusammen mit den Strömen von atomisierten Kraftstoff zu bewirken,
Mitteln (19, 21) zur Zündung des atomisierten Kraftstoffes im Flammrohr (3) stromabwärts
von seinem Einlaßende,
und Mitteln (12, 13) zum Einführen von Luft in dieses Flammrohr (3) an mindestens
einer Stelle längs seiner Länge zur Vermischung mit dem atomisierten Kraftstoff.
1. Brûleur à combustible liquide, caractérisé en ce qu'il comprend la combinaison
de:
un tube à flamme (3) présentant une extrémité d'entrée et une extrémité de sortie,
une chambre de pulvérisation (52) communiquant avec ladite extrémité d'entrée du tube
à flamme et qui enferme des pulvérisateurs de combustible (26, 26') pour faire passer
du combustible pulvérisé dans le tube à flamme (3) à travers des ouvertures dans une
paroi intermédiaire (51) séparant le tube à flamme (3) de la chambre de pulvérisation
(52),
lesdits pulvérisateurs (26, 26') comprenant plusieurs chambres creuses sous pression
qui présentent chacune une surface extérieurs lisse et, ménagé dans cette dernière,
un petit orifice traversant (29, 29'), un équipement (23, 23') pour produire un écoulement
de combustible sous la forme d'une mince couche sur chacun desdits orifices traversants
et un équipement (27, 27') pour introduire de l'aire sous pression dans chacune des
chambres sous pression (26, 26') afin de rompre cette mince couche au niveau de l'orifice
(29,29'),
un moyen (54) pour supporter les chambres sous pression (26, 26') dans la chambre
de pulvérisation (52) de façon à permettre aux courants dirigés de combustible pulvérisé
sortant de celle-ci d'être envoyés à travers les ouvertures respectives de la paroi
intermédiaire (51) à l'intérieur du tube à flamme (3) dans des directions s'étendant
le long de l'axe central du tube à flamme afin de brûler sensiblement tout le combustible
pulvérisé à l'intérieur du tube à flamme (3),
des moyens (56, 56'; 66, 66') pour introduire de l'air dans la chambre de pulvérisation
(52) de façon à permettre à de l'air à faible vitesse de sortir par lesdites ouvertures
de la paroi intermédiaire et ce conjointement avec les courants de combustible pulvérisé
et l'air sous pression sortant de chaque chambre sous pression (26,26'),
des organes (19, 21) pour enflammer le combustible pulvérisé dans le tube à flamme
(3) en aval de son extrémité d'entrée,
un premier équipement (50) pour introduire de l'air dans le tube à flamme (3), à proximité
mais en aval de son extrémité d'entrée, avec une composante tangentielle de façon
à produire dans le tube à flamme (3) un seul tourbillon tangentiel afin de favoriser
le mélange d'air avec le combustible pulvérisé et de maintenir la flamme éloignée
de la surface intérieure du tube à flamme au voisin- nage de son extrémité d'entrée,
un second équipement (12, 13) pour introduire de l'air dans le tube à flamme (3),
dans au moins une zone située en aval de la zone d'introduction d'air par ledit premier
équipement (50) et en aval de l'endroit d'allumage du mélange combustible-air par
lesdits organes d'allumage (19, 21), a une vitesse et dans une direction propres à
entraver le tourbillon tangentiel produit par ledit premier équipement de manière
à permettre à la flamme de s'étendre jusqu'à la paroi du tube à flamme et à rendre
possible une combustion sensiblement complète à l'intérieur des limites du tube à
flamme (3).
2. Brûleur selon la revendication 1, caractérisé en ce qu'une paroi (57) protectrice
contre le rayonnement thermique et percée de trous est supportée à proximité mais
à une certaine distance du côté de la paroi intermédiaire (51) situé en regard du
tube à flamme (3).
3. Brûleur selon la revendication 2, caractérisé en ce qu'il comprend en outre pour
chaque chambre sous pression (26, 26') une tubulure conique (17, 17') débitant le
combustible pulvérisé sous forme de jet, chaque cône (17, 17') débitant le combustible
pulvérisé sous forme de jet étant tronqué en ayant sa plus grande extrémité située
au voisinage de l'orifice traversant (29, 29') de la chambre sous pression correspondante
(26, 26') et en s'étendant à travers une ouverture respective de la paroi intermédiaire
(51) et de la paroi (57) protectrice contre le rayonnement thermique.
4. Brûleur selon la revendication 2 ou 3, caractérisé en ce que la paroi protectrice
(57) et la paroi intermédiaire (51) présentent une ouverture centrale (59) pour produire
un écoulement d'air à partir d'une source (55) d'air comprimé le long de l'axe central
du tube à flamme (3).
5. Brûleur selon la revendication 4, caractérisé en ce qu'il comprend en outre un
tube central (53) s'étendant à partir de la source d'air et communiquant avec l'ouverture
(55) de la paroi intermédiaire (51) avec l'ouverture (59) de le paroi protectrice
(57).
6. Brûleur selon l'une quelconque des revendications 1 à 5, caractérisé en ce que
ledit premier équipement (50) comprend plusieurs registres prévus dans la paroi du
tube à flamme.
7. Brûleur selon l'une quelconque des revendications 1 à 6, caractérisé en ce que
ledit second équipement comprend plusieurs orifices (12, 12') situés dans le tube
à flamme (3) sensiblement au milieu de la longueur de celui-ci.
8. Brûleur selon l'une quelconque des revendications 1 à 6, caractérisé en ce que
ledit second équipement comprend plusieurs évidements (13) situés dans le tube à flamme
(3) sensiblement à l'extrémité de sortie de celui-ci.
9. Brûleur selon l'une quelconque des revendications 1 à 8, caractérisé en ce que
ledit second équipement (12, 13) comprend plusieurs orifices (12) situés dans le tube
à flamme (3) sensiblement au milieu de la longueur de celui-ci et plusieurs évidements
(13) situés dans le tube à flamme (3) sensiblement à l'extrémité de sortie de celui-ci.
10. Brûleur selon l'une quelconque des revendications 1 à 9, caractérisé en ce qu'il
comprend des moyens (56, 56'; 66, 66') permettant de faire régner dans la chambre
de pulvérisation (52) une pression supérieure à celle atmosphérique.
11. Brûleur selon la revendication 10, caractérisé en ce qu'il comprend en outre des
moyens de canalisation d'air pour faire passer de l'air par l'intermédiaire des deux
équipements (50; 12, 13) à l'intérieur du tube à flamme 3.
12. Brûleur selon la revendication 11, caractérisé en ce que lesdits moyens de canalisation
d'air comprennent un tube (1) présentant un diamètre plus grand que le tube à flamme
(3) et entourant celui-ci de façon à former un conduit annulaire.
13. Brûleur à combustible liquide, caractérisé en ce qu'il comprend la combinaison
suivante d'éléments constitutifs:
un tube à flamme (3) présentant une extrémité d'entrée et une extrémité de sortie,
une chambre de pulvérisation (52) communiquant avec l'extrémité d'entrée du tube à
flamme (3) et qui enferme des pulvérisateurs de combustible (26, 26') pour faire passer
du combustible pulvérisé dans le tube à flamme (3) à travers des ouvertures dans une
paroi intermédiaire (51) séparant le tube à flamme (3) de la chambre de pulvérisation
(52),
lesdits pulvérisateurs (26, 26') comprenant plusieurs chambres creuses sous pression
qui présentent chacune une surface extérieure lisse et, ménagé dans cette dernière,
un petit orifice traversant (29, 29'), un équipement (23, 23') pour produire un écoulement
de combustible sous la forme d'une mince couche sur chacun desdits orifices traversants
et un équipement (27, 27') pour introduire de l'air sous pression dans chacune des
chambres sous pression (26, 26') afin de rompre cette mince couche au niveau de l'orifice
(29, 29'),
un moyen (54) pour supporter les chambres sous pression (26, 26') dans la chambre
de pulvérisation (52) de façon à permettre aux courants dirigés de combustible pulvérisé
sortant de celle-ci conjointement avec l'air sous pression qui passe par les orifices
(29, 29') des chambres sous pression (26, 26') d'être envoyés, à travers les ouvertures
respectives de la paroi intermédiaire (51), à l'intérieur du tube à flamme (3) dans
des directions s'étendant le long de l'axe central du tube à flamme (3),
des moyens (56, 56'; 66, 66') pour faire régner dans la chambre de pulvérisation (52)
une pression supérieure à celle atmosphérique de façon à permettre à de l'air à faible
vitesse de sortir également par les ouvertures de la paroi intermédiaire (51) en même
temps que lesdits courants de combustible pulvérisé,
des organes (19, 21) pour enflammer le combustible pulvérisé dans le tube à flamme
(3) en aval de l'extrémité d'entrée de celui-ci, et
un équipement (12, 13) pour introduire de l'air dans le tube à flamme (3) dans au
moins une zone de son étendue longitudinale afin de mélanger cet air avec le combustible
pulvérisé.