Note: Descriptions are shown in the official language in which they were submitted.
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This invention is directed to improvements in fuel
burners using oil or gas.
More particularly, the invention is directed toward
improvements in flame retention head assemblies used in fuel
burners.
Flame retention head assemblies are used to confine the
fuel sprayed from a nozzle, and the resulting flame, in a speci-
fic pattern, thus eliminating the need for a combustion chamber.
The assemblies provide an increase in heat transfex from the
burner thereby improving burner efficiency, and also improve
flame stability.
Effective flame retention head assemblies have means
for rapidly mixing the sprayed fuel with air to obtain air-fuel
mixes providing the best possible combustion efficiency. One
effective known assembly is shown in my earlier United States
patent 3,733,169, issued May 15, 1973. This assembly employs
both a spinner plate and a slotted flange, spaced downstréam
from the spinner plate, to swirl and mix air and fuel for good
combustion results.
It has however been discovered that even more effi-
cient combustion results, and flame pattern control, can be
obtained by providing an additional air supplying means between
the spinner plate and slotted flange. More importantly, this air
supplying means can be adjusted to control the amount of air
supplied, thus providing much better control over the combustion
process.
Other changes to the assembly, as will be apparent,
have also been made to provide a more efficient turbulence
thus combustion process.
The flame retention head assembly according to the
present invention is suited for use in the air tube of a fuel
burner having a fuel nozzle mounted coaxially within the air
tube. This assembly comprises a tubular member concentrically
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mounted within the air tube just in front of the fuel nozzle.
The tubular member comprises a conical section, a cylindrical
section joined at one end thereof to the larger end of the
conical section, and an outwardly flaring flange section joined
at the smaller end thereof to the other end of the cylindrical
section and dished to provide a convex outer surface. The
assembly also comprises a spinner plate mounted in the smaller
end of the conical section of the tubular member and adapted to
mix and swirl air and fuel. This spinner plate has a central
opening therein defined by a continuous annulus, and has vanes
in its outer periphery extending outwardly from the continuous
annulus. In accordance with the invention, the cylindrical sec-
tion of the tubular member has circumferentially spaced openings
therein; and the outwardly flaring flange section has a row of
circumferentially spaced, elongated slots therein. These openings
and elongated slots pass air into the tubular member when the ` `
assembly is in operation, whereby the conical section provides
a first mixing and heating chamber wherein primary combustion
takes place, the cylindrical section provides a second mixing
¢ chamber, and the flange section provides a third mixing chamber.
An embodiment of the invention will now be described
in detail having reference to the accompanying drawings in which:
Fig. 1 is a perspective view of the flame retention
head assembly installed in an air tube;
Fig. 2 is a partial cross-section view of the assembly
in the air tube;
Fig. 3 is a detail view of an alternative construction
for part of the assembly; and
Fig. 4 is a cross-sectidnal detail view of the alter-
native construction shown in Fig. 3.
As shown in Figs. 1 and 2 the flame retention headassembly 1 is mounted within the air tube 3 of a fuel burner
and in front of a fuel nozzle 5 mounted coaxially within the
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tut~e 3.
The assembly l has a circular tubular member 11. The
tubular member ll preferably has three sections; a first conical
section 13 at one end, a second intermediate cyllndrical section
15 which is joined at one end to the large end of conical section
13, and an outwardly flaring flange 17 extending from the other
end of the cylindrical section 15.
A spinner plate 21 is mounted at the small end 23 of
the conical section 13 of member 11. The plate 21 extends per-
pendicular to the longitudinal axis of the tubular member 11.
The spinner plate 21 has a central fuel and air opening 25,
and vanes 27 about its peripheral edge for imparting an initial
swirling motion to the air and fuel mixture within member ll.
A circular row of circular openings 31 are provided
about cylindrical section 15 in member ll to pass air. Means 33
(shown out of position in Fig. 1) are preferably provided to
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adjust the effective working size of these openings 31. The
adjustment means 33 can comprise a flexible strap or band 35
with means 37 at its ends 39 for tightening or clamping the strap
35 about cylindrical section 15. The tightening means 37 comprise
a bolt or screw 41 threaded through holes in the ends 39 of strap
35. To adjust the working size of openings 31, the strap 35 is
loosened and slid along cylindrical section 15 to cover to desired
portion of openings 31. The strap 35 is then tightened in place.
A circular row of elongated slots 45 are also provided
in flange 17 to pass air. The slots 45 are angled to provide
a further swirling motion to the air passed, the swirling motion
being in the same direction (or opposite resulting in more
violent mixtures) as that initially imparted by vanes 27. The
flange 17 is dished to provide an outer convex surface 47. This
shape reduces "combustion" noise from the assembly during use.
The diameter of the outer edge 49 of flange 17 is substantially
the same as the inner diameter of tube 3 as shown in Fig. 2.
Means 51 are provided for mounting the assembly 1
within tube 3. The mounting means 51 comprise rods 53 attached
at one end to the end 23 of conical section 13. The other ends
of the rods 53 are attached to a bracket 55 mounted about
nozzle adaptor 5. The assembly l is mounted concentrically
within tube 3 with spinner plate 21 just in front of nozzle 5
and with opening 25 centered with respect to the nozzle.
During operation of the air burner, ignition air
is supplied from the air tube 3, along with fuel from nozzle 5,
through opening 25 in spinner plate 21 into conical section 13
of member 11. Primary combustion takes place in a first mixing
and heating zone chamber "A" defined by section 13, aided by
the swirling action imparted to the burning fuel-air mixture
by air passing through vanes 27 in plate 21.
Cylindrical section 15 provides a second mixing chamber
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"B" into which air is passed via openings 31 to promote more
complete combustion. The amount of air can be varied if adjust-
ing means 33 are employed in reaction zone.
Flange section 17 provides a third mixing chamber "C"
into which air is swirled via slots 45. Since the slots 45 are
preferably angled, a swirling action is provided to ensure
better combustion. Also defined as luminous flame zone.
Various modifications can be made to the assembly
described. Instead of elongated cut out slots 45, the flange
17 can be provided with punched slots 45' as shown in Figs. 3
and 4. The flaps 61 punched inwardly to form slots 45' provide
guide means inducing a better swirling action.
Either slots 45 or 45' can be angled to provide a
swirling motion in opposition to that provided by vanes 27
to obtain a more violent mixture.
If desired, flange 17 can be made slightly smaller in
diameter than the inside diameter of tube 3. Fingers (not shown)
would extend radially out from the flange to position it within
tube 3. The annular gap between flange 17 and tube 3 provides
for an air flow which cools the tube and assembly 1.
The annular gap also helps produce a narrower and
longer flame pattern due to the high speed air flow from the
gap. The closer the flange is positioned to the tube, the
shorter and wider the flame pattern becomes.
The shape of conical section 13 can also be used to
determine the flame speed. A wide angled conical section 13
decreas~s Elamc speed while a narrow angled conical section 13
irlcreases flame speed.
It will be seen that many adjustments or variations
can be made in the basic assembly to provide optimum combustion
efficiency. The assembly of the present invention has been
found to provide a very high flame temperature as compared to
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known conventional equipment. The assembly also is very economi-
cal, reducing fuel requirements by up to 25%, and clean, reducing
combustion emissions by up to 75~. This is due to the more
complete combustion obtained by the assembly. The assembly
makes much more efficient use of the air flow in tube 3. When
flange 17 is spaced from tube 3, five different air paths are
provided to mix, swirl and shape the flame. Even when flange
17 lies against tube 3, four air paths are still provided, to
supply constant combustion air ratio. For example, when flange
17 lies against tube 3, band 35 is loosened and adjusted so as
to compensate combustion air change.
