Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BURN~R HEAD
Field of Invention
The present invention relates to a novel burner head for use with
apparatus employed in the conversion of oil fired heating furnaces
to natural gas or propane fired furnaces where the oil burner head
is replaced by a burner head assembly adapted to burn natural gas.
In particular the invention herein disclosed provides a burner head
assembly for use in domestic gas power burners which develops a short
self contained flame and which incorporates the standard oil burner
housing to carry a volume of high velocity air to become the combus-
tion air stream necessary to allow a gas burner to maintain a stable
flame while discharging combustion by-products at adequate rates.
Background of the Invention
There is a present demand for devices and means for converting
furnaces using oil for combustion heat to ones capable of using gas.
It is common in the domestic marketplace to replace a whole furnace
when it is desired to convert to gas from oil as the source of fuel.
There is a need for a gas burner that can be used in the combustion
chamber of an oil furnace. Such a burner must be capable of creating
a self controlled flame and must have fan and motor means of sufficient
capacity to create a velocity of air to maintain a stable flame.
The oil to gas conversion burners now known are fan assisted type
burners. Fan assisted burners have combustion air supplied by a fan or
blower of sufficient force pressure to overcome the burner resistance
only and the flame produced at the burner head is of a long laminar
shape. A long laminar flame cannot be properly contained in the combust-
ion chambers of the commonly used domestic oil fired furnaces. The long
flames created by the commonly used gas burners causes the heat exchan-
gers to readily burn out in oil furnaces since they have been designed
to contain the bushy flames common to oil burners.
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Gas burner manufacturers have made various types of flame spreader
devices for attachment to gas burner heads to maintain the gas flame
within the oil furnace combustion chamber and thereby to protect tne
furnace heat exchangers, but it is known that the devices developed
to date fail from thermal fatigue after short usage and are not
therefore, acceptable in the domestic burner market.
Another disadvatage of fan assisted burners is that they will not
function in an appliance that has restrictions such as baffles or
revertable flues. Known burners cannot achieve the pressure required
to move the combustion by-products through the appliance and at the
same time maintain acceptable by-product levels. Attempts at increas-
ing the fan capacity to meet the required pressure levels have merely
resulted in creating an unstable flame.
Object of the Invention
It is the principal object of the invention to provide an oil
furnace combustion chamber with a burner head capable of burning natur-
al gas or propane gas with a short bushy flame while maintaining a
high velocity stream of exit combustion by-products.
- Summary of the Invention
It is known that gaseous infusion flames are not commonly used
in furnaces for heating whereas pre-mixed air and fuel are common.
Gaseous infusion burning methods are known to create flame instability
and give unacceptable levels of carbon monoxide. The applicants
herein have found that stabilization of the flame can be achieved by
creating areas of low air and gas velocities at the point in the
combustion head where the fuel and the oxidizer are brought together
and maintained in the proper proportion for the reaction of combustion.
The following described structure has achieved the desired result.
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The flame retention head for a gas burner herein, consists of
a turbostatic means set in the air passageway of the burner and spaced
across the path of travel of the flow of air driven into the air
passageway. The turbostatic means is close to the end of the gas duct
which leads axially through the passageway for the air and terminates
with the passageway within the combustion chamber of the furnace.
The burner head comprises a pair of flame stabilizer discs fixed across
and to the end of the gas conduit. The outer facing disc blocks the end
of the gas conduit and is of smaller diameter than the inner disc. The
discs are spaced apart sufficiently close only to accomadate a portion
of the end of the gas conduit having a plurality of upwardly facing ports
enclosed therebetween.
Co-axial apertures are bored through each disc in concentric array
with the gas conduit ports- centred about the rows of apertllres thus
formed. The natural gas fuel is introduced to the head from the ports
between the discs of the head and enters the head radially of the discs.
High velocity oxidation material such as air is introduced to the head
from the air passageway which terminates behind the inner disc. There
is a space between the end of the outer wall of the passage for the air
and the edges of the discs thereby allowing air to flow past and around
the head. Some of the air passes through the apertures in the inner disc
and mixes there with the gas emerging from the conduit ports and
then pass through the apertures in the outer disc mixed ~ogether and
with low turbulent velocities where it is readily ignited. The partial
pre-mixing of the air and gas at the central front region of the head
ensures the existence of a stoichiometric mixture there during operation
of the burner and the low velocity of the mixture in the front of the
head ensures a continuous flame stability for the device.
Only a fraction of the gas is pre-mixed and carried through the
apertures in the front disc. Most of the gas reaches the periphery of
the front disc by the apertures in an unmixed state and is there mixed
with the air coming through the outer row of apertures in the inner disc
which open directly into the space forward of the head.The larger
_nner disc also serves as a bluff obstacle preventing blowoff and also
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serves to create an inner reverse flow in the region directly in front
of the burner. The gas-air mixture made at the front of the head
by the flow of air from the peripheral sides of the burner and discs
is readily ignited by the constantly stabilized portion of the mixture
forming in the centre region of the outer disc.
The high velocity of the air emerging from between the rear disc
and the wall of the air passageway, which has been turbulated by the
turbo-static disc, shapes and constrains the flame from bushing out.
In addition the air leaving the space between the discs and the air
passage becomes a source of secondary air for serving to be carried by
the combustion reaction into and toward the combustion zone constantly
stabilized in the centre region of the outer disc.
In The Drawings
With the foregoing object in view and such other objects that become
apparent from consideration of this disclosure, the present invention
consists of the inventive concept which is comprised, embodied and
included in the construction, method and combination of parts herein
exemplified reference being had to the accompanying drawings in which
like reference numerals refer to like parts.
Fig. 1 shows a gas burner,partly~ in section, mounted for use
in the combustion chamber of an oil ~urnace, shown partly in section.
Fig. 2 is a front view of the burner head of the invention showing
the relative sizes of the apertures in the discs.
Fig. 3 is a view of the burner head from above with the air
passageway partly cut away and the gas conduit cut partly away to show
the dimensions of both relative to the discs.
The Preferred Embodiment of the Invention
The burner head of the invention is shown in figure 2 and is
enumerated 10 It comprise a pair of discs 12,13 spaced apart from
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one another by spacers 21,22 which create the space or gap 20 between
the discs 12,13. Three rows of concentric holes or apertures, 14,15,16
are bored into each disc and a fourth row 17 is bored into the peripheral
edge of inner disc 12 to open into the region in front of the burner
head 10 uncovered by disc 13 as indicated by the Fig. 2. A spark igniting
means 24 is shown in front of head 10, with the actual spark being created
from contact 24 to ground screw 25 on a signal from heat sensor 66.
In Fig.2 a gas conduit pipe 18 is shown with the head assembly 10,
consisting of the pair of spaced apart discs 12,13 , fixed to the conduit
pipe 18 by a collar flange 30 mounted to the disc 12. The outer end 31 of
conduit 18 abutts the inner side of disc 13 in sealed shut mode. The gas
is discharged from the conduit 18, only by a series of equal diameter
ports 25 spaced equidistant apart around the upper part and sides of the
circumference of the conduit pipe 18 extending into and between the disc
space 20 as shown in figure 2. No ports issue along the bottom side of
the portion of the pipe 18 extending into space 20.
In Fig. 1 a typical oil furnace 35 is shown with the conversion
burner of the present invention, 38, installed with the burner head 10,
set into the combustion chamber 36. The burner is shown partly in section
to indicate the location of the gas delivery conduit 18 directed toward
the head and axially mounted within the burner casing 27 which has been
converted to be the forced air passageway from the fan and motor means
37 of the burner to the head 10.
A vane type air tubulator 28 is attached near the head of the burner
to provide turbulence to the air being driven outwardly toward the head
10 by the fan and motor means 37 of the burner 38.The vanes 41 are shown
in figure 3 and are spacedaround the central axis of the conduit pipe 18.
The end of the air passageway enclosure wall 27 has its termination
adjacent the plane of the outer disc 13 but is not attached to the head,
as they remain spaced apart by an opening gap 44.
Numeral 40 indicates the bushy shaped flame created by the device.
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Construction and O~peration of the_lnvention
The following dimensions have been found to be preferred for a burner
head used in a flame retention gas burner design incorporating a com-
mon oil burner housing.
The head consists of two (2) eighteen gauge (18G) stainless steel discswhich are separated from each other by from 1/16 inches to 1/4 inches.
The smaller outer disc is of three inch (3") diameter and is truncated
approximately one inch (1") below the center. At the center of the
disc, there is a one inch (I") diameter embossment approximately 1/8
inches deep.
There are three (3) rows of concentric holes approximately of 1/8 inch
diameter bo~ed in the outer disc. The first row (12 holes) is pierced
every thirty degrees (30) starting at the twelve o'clock position at
a radius of 5/8 inches. The second row (21 holes) is pierced in a like
manner every fifteen degrees (15) at a radius of 15/16inches. The
third row (14 holes~ is pierced in a like manner every fifteen degrees
(15) at a radius of 1-5/16 inches starting at fifteen degrees (15)
from the twelve o'clock position but omitting the twelve o'clock
position. Symmetry exists about the twelve o'clock position.
At a radius of 1-1/4 inches, three (3) holes of 1/8 inches diameter arepierced every one hundred and twenty degrees (120) starting at the
twelve o'clock position (mounting holes).
The larger inner disc is a doughnut-like configuration of 3-5/8 inches
outer diameter and approximate1y 7/8 inches inner diameter, and it also
is truncated one inch (1") below the center.
There are four (4) rows of concentric holes bored in Lh~ innLr disc,
each hole having approximately 1/16 to 1/8 inches diameter.
The first row (12 holes) ~s pierced every thlrty degrees (30) startingat the twelve o'clock position at a radius of 5/8 inches. The second
row (21 holes) is pierced in like manner every fifteen degrees (15)
at a radius of 15~16 inches. The third row (14 holes) is pierced every
fifteen degrees (15) at a radius of 1-5/16 inches starting at fifteen
degrees (15) from the twelve o'clock position but omitting the twelve
o'clock position. The fourth row (77 holes) is pierced every fifteen
degrees (15) starting at the twelve o'clock position at a radius of
1-21/32 inches. Symmetry exists about the twelve o'clock position.
At a radius of 1-1/4 inches, three (3) holes of 1/8 inches diameter arepierced every one hundred and twenty degrees (120) starting at the
twelve o'clock position. These holes are subsequently extruded to a
height of from 1/16 to 1/4 inches, thus forming the necessary spacing
between the smaller outer disc and the inner larger disc.
The turbo-static disc, a partially vaned configuration of 3-3/8 inches
diameter, is attached at the truncated portion of the inner disc at
the bottom of the air tube approximately one inch (I") behind the inner
disc.
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With the above dimensioned burner head, gas is fed to the head under
pressure from three to six inches of water column (3" to 6" W.C.) by
means of a conduit of a?proximately 7/8 inches outer diameter and
1/2 inches inner diameter (nominal 1/2" black pipe, Schedule 40).
Gas is introduced at regular intervals in the radial direction be-
tween the two (2) discs. The gas conduit is from 7-11/16 inches to
13-11~16 inches long. There are seven (7) holes, each from 1/16
inches to 3/16 inches diameter pierced every thirty degrees (30)
starting at the twe]ve o'clock position at a distance of 3/16 inches
to 5/16 inches from the open end of the conduit to the centreline
of the holes. These ho1es are the gas ports.
The two (2) stabi1izer discs, held together by screws at the three
(3) mounting holes on the 1-1/4 inch radius, are secured to the
gas conduit in such a manner that
i) the twelve o'clock position of the two discs (burner head)
corresponds to the twelve o'clock position of the gas conduit
ii) the open end of the gas conduit butts up tightly on tl-e emboss-
ment of the outer disc
iii) the gas ports are completely (no impingement) located in the
small distance between the two discs
The burner head arrangement, with the gas conduit and turbo-static
disc in place, is positioned in a four inch (4")-diameter air tube
such that the inner disc is approximately from 1/16 inches to 1/4
inches in front of the air tube.
A power blower delivers a controlled volume of high veloci~y colllbu~-
tion air behind and around the periphery of the burner retention head.
Some of this high velocity air passes through the bores of the inner
disc, mixes with the gas, and emerges at low turbulent velocities
through the bores of the outer disc where it is readily ignited. The
velocity of the air/gas mixture in front of the burner head is suffi-
ciently low to continuously maintain flame stability.
