Note: Descriptions are shown in the official language in which they were submitted.
~Z~37~ .
This invention relates to a blue fl~me burner
for liquid fuels.
l~no~n in the art a.re blue ~ e burners for
l~cluid uels ~hich, while being much more efficient
th~n traditional white fl~me ~rners, require the
provi~ion of two discrete combustion air feed paths
to the burner combustion chamber. The two paths are
conventionally designated primary air path and
secondary ~ir path~ respectively. The provision of
such dual path involves, in addition to designing
and construction problems, also the solution of
complex problems connected with the volume and
~elocity metering of the air flo~n therethrough, as
well as of mutual correlation and interdependence.
Thus the task of this invention is to
provide a bl~e fl~ne burner ~or liquid fuels which,
additionally to substantially removing the cited
problems and shortcomings affecting prior burners, can
afford a definitely superior performance level.
Within this task it is an object of the invention to
provide a burner as 1~ oat~t, ~hich affords,to all prac-
tical e~ects, a compl~te combu~tio~, leaving no unbu~ned
portions of the fuel, by ensuring that the combustion
can ta~e place in a stoichiometric ratio o~ fuel ~o com-
bustion air, or a ratio very close to the theoretical
stoichiometric values. This means that the excess air
flowing through the burner is nil or close to ~ero,
for a higher thermal effici0ncy of the kurner~
~k
~2(3~L373
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A ~urther object of this invention is to
provide a burner as indicated, which has a very
simple construction, comprises a minimum of
components, can be readily and conveniently
assembled and disassembled, and can be manufactured
at a highly competitive cost.
These and other objec~s, such as will be apparent
hereinafter~ are achieved by a blue ~lame burner for
liquid fuel~, characterized in that it comprises an
externally cooled com~lstion chamber, a pre-heating
chamber for combustion air from a source of
pressurized air, a calibrated neck wherethrough said
pre-heating cha~ber is com~nicated to said
combustion chamber, an atomizing injector cantilever
mounted inside said calibrated neck and being
adapted to scatter atomized f~el toward said
combustion chamber, and a pressurized ~uel intake
conduit arranged within said air pre-heating chamber
in heat exchange relationship therewith ~nd being
connected to a source of pressurized ~uel.
Further aspects and advantages will become
apparent a~ter considering the following detailed
description of a preferred embodiment of this
invention, given herein by way of example and not .
of limitation, in conjunction with the accompanying
illustrative drawings, where:
Figure 1 is a schematic view~ in elevation and
longitudinal section, of a burner according to the
invention;
~2(~373
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Figure 2 is a schematic elevation view of the
~urner of Fi~ure 1, as placed at the inlet end of
a refractory material lined chamber; and
Figure 3 is a C02 vsO 2 percent ~raph.
With re~erence to Figures 1 and 2, where
similar parts have been designated with the same
reference numerals, this burner 1 has an elongate
hollow boay ~, a calibrated nosepiece 3 removably
attached to one end of the hollow body 2, and an end
cap 4, removably attached to the other end of the
hollow body. The latter is ~ormed, at an intermediate
region thereof~ wlth an annular increased-thickness
portion~ whereat a restriction or neck 5 is defined
internally. The annular thickened portion in the
hollow body 4 acts as a partition member separating
two internal cavities in the body 4, namely a front
cavity 6 and rear cavity 7. The front cavity 6 is,
thus~ delimited on the front by the nosepiece 3 and
constitutes the burner combustion ehamber~ ~hich is
cooled externally by a fluid circulated at 6a~ while
the rear cavity 7 is closed by the end cap 4 and
constitutes a combustion air pre-heating chamber, as
will be explained hereinafter. The chambers 6 and 7,
and the neck 5~ are all aligned together ~long the
longitudinal axis x-x.
At the neck 5, there is arranged, in a removable
manner, a bushing 8, which abuts externally and
peripherally against the inner wall of the neck 5
and has an inner bore 9 convergent toward its
calibrated end 10 facing the chamber 6.
The end cap 4~ and accordingly the chamber 7, is
comn~nicated9 throu~h a hole 11 formed throu~h a lug
12 whereto is secured one end of a preferably flexible
hose line 13, to the delivery end of a blower or
compres~or 15 of the two-s-tage type which is arranged
to deliver pressurized air into the chamber 7. ~hrough
the end cap 4, a hole 16 is al~o formed which extends
coaxial with the axis x-x, and is connected to a
a pressurized liquid ~uel (e.g. Diesel oil) supply
conduit 17. I~ore speci~ically, the hole 16 is formed
through an inside lug 18 which,from the rear wall of
the end cap ~ extends in cantilever relationship along
the axis x-x over the entire length of the end cap.
At the free end of the lug 18~ there is secured one
end of a conduit or line 19, which enters the bushing
8 cantilever-fashion. The free 6nd of the conduit 1g
accommodates, mounted therein, an atomizing inaector
device 20~ which barely clears with its spray noæ~le
21 the calibrated end 10 of the bushing 8.
On that section of the line 19 which e~tends
outside of the bu.s~;ng 8~ there is slidably mountedg
and adjustably fastened, a disk ~r diaphragm 22 which
fu~ctions as a restrictor elenent for the air coming
~rom the passage 11 and directed to the com~ustion
cham~er.
~ aterally to the restriction 57 at the thickened
region o~ the hollow body 29 there are formed holes
intended to accommodate flame ignition and control
3 metal el~ctrodes 24, which protrude into the
3~3
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combustion chamber 6.
The pressurized fuel 3upply line 17 is in turn
connected, with the interposition of a control
solenoid val~e 25, to a suitable fuel pump 26.
At the intake mouth 27 of the blower 15, a conduit
28 is provided which can be shut off by means of a
movable shutter 29 driven by a solenoid valve 30.
Upstream of the shutter 29 is located a metering
device 31 arranged to control the flow rate of the
combustion air directed to the burner.
Preferably, the metering device 31 can be adjusted
by means of a micrometric adjustment pin screw.
The burner described hereinabove operates in a
very simple manner. After starting the blower 15 and
actuating the pump 26, the shutter 29 will be in its
air shut~off position; however~ thanks to a central
hole 32 provided thereîn, a sufficient amount of air
can still be admitted to the combustion chamber 6 to
cause ignition. Once the fuel has been so ignited, the
solenoid valve 30 ~ill be controlled, by an electronic
control unit not shown in the drawings, to open9 so
- that pre~surized combustion air can be delivered into
the chamber 7 at a pressure and volume consistent with
the amount of fuel issueing from the atomizing
injector 20, and in all cases in stoichiometric
proportion for burning the particular fuel being used.
In operation~ the hollow body 2 will be heated
at the combustion chamber 3, and transfer part o~ its
heat by conduction to both the air within the chamber
7 and fuel flowing through the lug 18. ~y con~ection,
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the air contained in the chamber 7 will in turn
aasist in the transfer of heat ~rom the inner walls
of the ch~nber 7 to the condui-t 19, thereby the
oncoming ~uel to the atomizing injector device 20
is adequately pre-heated.
Irhe air contained in the chamber 7 initially
undergoes expclnsion in flowing from the hole 11 to
that portion of the chamber 7 ~vhich is located
upstream o~ the diaphragm 22~ rrhe diaphragm 22 will
ins~ead force ~he air to flow peripherally past it
and then sweep the inner wall of the tubular body 2,
thereby its velocity is increased. Between the
diaphragm 22 and ~ shing B, the air is subjected to
further expansion, and by virtue of the bushing 8
being conflgured to protrude in part, cæ~tilever-
~ashion, toward the interior of the chc~mber 7 from
the restriction or neck 5~ it undergoes a mixing and
thermal stabilization process prior to flowing through
the bore 9 in the bushing 8. Through the bore 9, the
air is uniformly distributed along and around the
atomizing injector device 20, and upon reaching the
calibrated end 10 of the bushing 8, it is directed
concentrically toward the interior of the chamber 9 t
to encircle the jet(s) of atomized fuel issueing from
the nozzle 21. It is important that the atomiæed ~uel
spray be focussed on the area of highest turbulence
of the combustion air being fed into the combustion
chamber.
~ith burners constructed as described hereinabo~e
and operating as herein detailed, efficiency rate
have been achieved on a regular basis which equal
or exceed 99 percent~ as against maximum rated
efficiencies of 8~-85 percent of comparable white
flame burner6 of conventional design and construction.
r~ioreover, besides the very high thermal
efficiency afforded by a burner according to this
invention, several other advantages can be secured,
among which:
- complete combustion of the fuel with total absence
of unburned residue;
- high temperature of the resulting flame emerging
from the combustion chamber 6;
- issue of polluting gases in negligible amounts; and
- very low maintenance costs, largely on account of
the absence of unburned products.
Tests have been carried out on a burner as
described above~ having its nosepiece 3 located at
the inlet end of a chamber 33 lined ~ith tiles 34 of
a refractory material, as shown in Figure ~ The
refractory material l;ning~ upon becoming red-hot~
will isRue light in the white-red bands with a high
emissivity. ~hus, inside the chamber 33 temperatures
in excess of 1,500C are to be achieved within few
minutes (3 to 5 minutes) from burner ignition.
~ith a burner 1 and chamber 33 as shown in
~igure 2, but associated with a small-size boiler
(having outside dimensions of 45 x 88 x 58 cm)
surrounded by a water jacket, actual tests have
provided the following values:
~urnace output 1 19000 Kcal/hour
~L2~137;~
Useful thermal efficiency ~5a,~
~lue gas temperature 176C
~xcess air 1.3
Smoke emission rate (Bach. app.) 0.0
C2 emission 14.5
CO emission .01~
As may be appreciated from the graph of Figure 3
(Ostwald triangle)~ ~or a content of carbon dioxide
of 14 5 percent, there only occurs a both theoretical
and practical excess of air of 1.3. Loreover, the
virtual absence of carbon monoxide from the combustion
products along wi~h the higll percentage of carbon
dioxide is a sure indication7 to all practical effects,
of all the fuel being ~urned completely~
15Actual tests have also sho~n that the sizing of
this burner to meet varying power recluirements in
diferent applications will depend o~ the varying and
mutual correlation of but a few structural elements.
~hese are the inlet port size of the metering device
31 (T), the port size (~) of the calibrated end 10 of
the nozzle 8~ the maximum inside diameter (C) of the
combustion chamber, the length (~ of the combustion
chamber, and the diameter ~B) of the nosepiece 3.
The following exemplary correlations of the a~ove-
specified values T~U,~,~ and B have shown to be
advantageous in practicing the invention:
Kcal/hour ~ (mm) U (mm) C (mm) ~ (mm) B ~mm)
10,000 34 17 65 192 22
30~0~000 10 20 65 162 32
50,000 16 19 65 212 42
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- 10 -
100,000 34 18 85 263- 55
r~he above-tabulated results relate to a fuel
delivery pressure of 18 kg/cm .
rrhe invention as described is susceptible to
many modi~ications and variations without departing
from the scope c~nd spirit of the instant inventive
concept.
The materials and dimensions used may vary to
suit -lndividual applicational re~uirements.
