Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
IMPROVED VAPOR FLAME BURNER AND METHOD OF OPERATING SAME
INTRODUCTION
[0001] This invention relates to an improved
burner and, more particularly, to an improved diesel fueled
burner which produces a vapor flame with an adjustable BTU
output.
BACKGROUND OF THE INVENTION
[0002] The use of diesel burners and heaters
is, of course, pervasive in industry. Diesel burners may be
powered where the use of electricity is required to operate
the burner and non-powered where the diesel fuel is manually
ignited to create a flame which is then self-sustaining
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until the fuel supply terminates.
[0003] If the diesel burner is powered,
auxiliary components such as fuel pumps, compressors,
combustion fans and the like combine in operation to produce
a fuel/air mixture leaving a nozzle where combustion
subsequently occurs, the ignition of the flame generally
being initiated by an igniter. Diesel fuel has a healthy
caloric content which results in relatively excellent BTU
output when the diesel fuel is ignited under satisfactory
combustion conditions.
[0004] In one form of such powered heaters,
electrically powered pumps may be used to pump a coolant
into an area adjacent the burner. The coolant is heated by
the burner and the coolant, in turn, may be used to heat
potable water through a heat exchanger where the potable
water is then used for shower or cooking purposes.
Alternatively, the heated coolant is routed through space
heaters where the heat from the coolant emanates into living
quarters for comfort. In yet a further embodiment, the
coolant itself may be potable water which is used for
showers and the like. And, further, the coolant may be used
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to heat a second coolant by way of a heat exchanger.
[0005] Such diesel burners are known. In one
such diesel burner, manufactured by International Thermal
Research Ltd., the owner of the present invention, and known
as the HURRICANE (Trademark) heater, a burner uses an air
aspirated nozzle which draws diesel fuel into the nozzle
when air is added to the nozzle by way of a compressor. The
air and fuel mixture emanate from the nozzle and combust,
initially by way of a igniter and, thereafter, by the heat
of the continued combustion to form a combustion flame
within a burner tube. The combustion flame creates the heat
required for heating the coolant or potable water
surrounding the burner tube within a coolant jacket or other
coolant container.
[0006] Another heater designed by International
Thermal Research Ltd. is a heater used for military
purposes, primarily within field kitchens. This powered
diesel fueled heater is known as the mBU (Modern Burner
Unit) heater. A large number of such heaters of this type
have been sold and used throughout the world. The MBU
heater does not heat a coolant. Rather, the heat from the
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combustion flame is used to provide heat for ovens, griddles
and the like generally used in field kitchens.
[0007] As noted, the MBU and HURRICANE heaters
both use an air aspirated nozzle to draw fuel into the
nozzle. The combustion of the fuel-air mixture occurs in a
burner tube. A low pressure airstream ensures efficient
combustion within the burner tube. These heaters have
operated in a satisfactory manner but there are certain
improvements that can be usefully made.
[0008] One disadvantage of existing burners
heretofore described is that the fuel-air combustion process
within the burner tube creates noise due in part to
turbulence within the air-fuel mixture. While proper heater
location and/or sound proofing may substantially reduce the
noise apparent to users, the noise may still be distracting
particularly when sleeping or relaxing in quiet conditions
and when the heater is located nearby. A second
disadvantage of the prior art burners is that the burner
tube required to support the combustion is necessarily of a
relatively large diameter to ensure efficient and adequate
combustion. This increases the size of the burner where a
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smaller footprint may be desirable due to limited space being
available for the heater. A third disadvantage of the prior art is
that combustion by-products of carbon monoxide and soot are always
present to a larger or smaller degree in a diesel fueled burner. The
combustion envelope is dependent on external factors such as
temperature and altitude which may change the percentage of
combustion by-products during combustion and adversely affect the
efficiency of the heater under certain conditions.
0009] Yet a further disadvantage is that the prior art burners
cannot be fully enclosed because the only combustion air available is
ambient air. The lack of the ability to enclose the burner results
in significant heat loss which adversely affects operating
efficiency.
0010] A vapor burner is described in some detail in United
States Patent 3,620,657 (Re. 28,679) to Robinson. The Re. 1679
patent teaches the use of ambient air for combustion and a constant
BTU heat output. There are advantages in increasing operating
flexibility and efficiencies of the burner in accordance with present
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invention.
SUMMARY OF THE INVENTION
[0011] According to one aspect of the
invention, there is disclosed a liquid fueled burner
comprising a burner head, a burner tube, a nozzle for
ejecting fuel into said burner tube, a counterflow chamber
surrounding a substantial portion of said burner tube, first
and second sets of perforations extending through said
burner tube into said counterflow chamber, said second set
of perforations being located adjacent said nozzle and said
first set of perforations being located distant of said
nozzle, an adjustable combustion fan to provide combustion
air to said burner tube and said counterflow chamber, said
burner head being operably connected to said burner tube and
means to increase and decrease the supply of said fuel and
to increase and decrease said combustion air.
[0012] According to a further aspect of the
invention, there is disclosed a burner utilising a liquid
fuel supply fuel line to supply liquid fuel to a nozzle, a
variable speed compressor to introduce air under pressure to
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said nozzle and to draw said liquid fuel into said nozzle to
produce an air-fuel mixture emanating from said nozzle into
a burner tube, an adjustable combustion fan to supply
combustion air to said burner tube, an igniter to ignite the
air-fuel mixture emanating from said nozzle and to commence
combustion of said air-fuel mixture within said burner tube,
a burner head, a counterflow chamber surrounding said burner
tube, a first set of perforations extending though said
burner tube located at the distant end of said burner tube,
said first set of perforations allowing the escape of at
least a portion of said fuel vapor in said burner tube into
said counterflow chamber, adding combustion air to said
counterflow chamber to form a flame within said counterflow
chamber, a second set of perforations extending through said
burner tube located adjacent said nozzle, said second set of
holes allowing the entry of fuel vapor from said counterflow
chamber into said burner tube and controls to increase or
decrease the supply of air to said nozzle and to said burner
head.
[0013] According to yet a further aspect of the
invention, there is disclosed a method of creating a
combustible vapor from a liquid fuel within a burner
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comprising the steps of introducing a liquid air-fuel
mixture into a burner tube from a nozzle, supplying
combustion air to said burner tube, passing at least a
portion of said air-liquid fuel mixture from said nozzle
through an igniter to ignite said air-liquid fuel mixture
into a flame within said burner tube, allowing said
combustion flame to emanate from a burner head located
downstream of said burner tube, allowing fuel vapor within
said burner tube to escape to a counterflow chamber
surrounding said burner tube via a first set of perforations
in said burner tube located distant from said nozzle,
supplying combustion air to said counterflow chamber to
combust said fuel vapor within said counterflow chamber,
heating at least a portion of the outside of said burner
tube with said flame in said counterflow chamber,
restricting the flame within said counterflow chamber by a
flame suppressor and allowing byproducts of said combustion
of said flame in said counterflow chamber to be reintroduced
to said burner tube through a second set of perforations
located in said burner tube at the end of said burner tube
adjacent said nozzle, terminating the operation of said
igniter after a predetermined time period wherein the
temperature within said burner tube is high enough to
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maintain vaporization of said air-diesel fuel mixture
emanating from said nozzle and allowing said flame within
said burner tube to extinguish, said flame appearing on said
burner head and inside said counterflow chamber.
[0014] According to still yet a further aspect
of the invention, there is disclosed a counterflow chamber
comprising a counterflow air chamber surrounding a burner
tube, a first set of perforations extending from said burner
tube into said counterflow chamber to allow passage of fuel
vapor from said burner tube, a second set of perforations
extending from said counterflow chamber into said burner
tube to allow combustion by products into said burner tube
and an inlet for combustion air to enter said counterflow
chamber and combust said fuel vapor within said counterflow
chamber thereby to heat the circumference of said burner
tube.
[0015] According to still yet a further
aspect of the invention, there is disclosed a burner head
for a burner comprising an outer flame surface with
perforations extending through said flame surface from the
outside of said flame surface to the inside of said flame
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surface, an inner baffle located within said burner head,
said inner baffle having perforations extending through said
baffle, said first outer flame surface and said inner baffle
being concentric, a first flame sensor outside said burner
head adjacent said flame surface and a second flame sensor
located within said burner head.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] Specific embodiments of the invention
will now be described, by way of example only, with the use
of drawings in which:
Figure 1 is a diagrammatic plan view of the burner
within its frame according to the invention and which
particularly illustrates the components used in support of
combustion within the burner;
Figures 2A and 28 are diagrammatic, isometric and
partial cutaway views, respectively, illustrating the
assembled burner according to the invention and in which
Figure 2B particularly illustrates the path of burner head
and counterflow chamber air supply air through the burner;
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Figure 2C is a diagrammatic side and partial
sectional view of the burner according to the invention
particularly illustrating the assembled igniter and nozzle
assembly and the counterflow chamber;
Figures 3A, 3B and 3C are diagrammatic side and
partial sectional views similar to Figure 2C, particularly
illustrating the burner phases during the transition from
the combusted air-fuel flame phase to the vapor combustion
phase;
Figure 4 is a diagrammatic front view of the front
panel member used with the burner of Figures 1-3;
Figures 5A and 53 are diagrammatic views of the
front and back face plates of the burner according to the
invention which facilitate the various air flow streams; and
Figure 6 is a diagrammatic isometric and partial
cutaway view of the burner head specifically illustrating
the outer and inner flame rods and further illustrating the
inner baffle positioned within the burner head.
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DESCRIPTION OF SPECIFIC EMBODIMENT
[0017] It will be appreciated that there are
some aspects of burner operation and fuel vapor formation
within the burner according to the invention that are not
wholly understood at the present time. Nevertheless, the
explanations given hereafter are being described as they are
understood by the applicants for the purpose of full
disclosure of the invention as it now appears.
[0018] Referring now to the drawings, a burner
according to the invention is illustrated generally at 100
in Figure 1. The burner 100 is particularly useful in
military field kitchens and the like which are used for food
preparation for troops and/or support personnel in the
field. The burner 100 is typically intended to be inserted
within an oven or under a griddle or a food preparation
container. It may also be used as part of another
appliance. The heat generated by the burner 100 heats the
oven, griddle, container or appliance.
[0019] The burner 100 has a number of
components required for supporting combustion. A compressor
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101, preferably being a variable speed compressor in order
to provide more or less air to the nozzle 102, provides air
to the burner nozzle 102 (Figure 2C) and a fuel pump 103
provides fuel to a fuel regulator 104 which is connected to
a solenoid 118 which is connected to the fuel block 115
(Figures 1 and 2C) which is connected to the nozzle 102.
The solenoid 118 is used to stop fuel flow after burner
operation is terminated to prevent fuel droplets from
leaving the nozzle 102 and from accumulating on the bottom
of the heater casing 123 and further to prevent fuel being
siphoned back form the nozzle 102 which allows a quick and
clean start of the fuel from nozzle 102. The fuel pump 103
is connected through a fuel filter 119 directly to the fuel
inlet 110 of the burner 100 which allows the entry of fuel
from a fuel storage device such as a tank or jerry can (not
illustrated). A combustion fan 111, preferably being a
variable speed combustion fan to provide more or less air to
the burner 100, provides combustion air to the burner tube
112 (Figure 20) by way of holes 113 in the nozzle tube 114.
Combustion fan 111 also provides combustion air to the
burner head 140 and to the counterflow chamber 150 through
holes 161, 162 (Figures 2A and 5A), respectively, as will be
described.
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[0020] A control board 120 (Figure 1) provides
control for the different phases of the burner 100 as will
be described. A 24V DC power supply is used with the burner
100 and the power cables are connected to the power
connector 121. A cooling fan 122 is provided within the
burner 100 to cool the components from the heat generated by
combustion. The cooling fan 122 takes cool air into the
heater casing 123 of the burner 100 through inlet louvers
130 (Figure 4) and expels the heated air through exit
louvers 135 on the front panel generally illustrated at 124
in Figure 4 of the heater casing 123. The cooling fan 122
also cools the electrical and mechanical components, just
described, following burner shutdown as will be described.
[0021] A carrying handle 131 (Figure 4) is used
for inserting and removing the burner 100 from the appliance
(not illustrated) in which the burner 100 is to be used. An
ON-OFF switch 132 provides for activation of the burner 100
and a rotary dial potentiometer 133 allows for increasing
and decreasing the heat output from the burner 100 as will
be described. An indicator light 134 provides an indication
of the phase of the flame emanating from the burner head 140
(Figure 2C) and the status of the burner 100 as will further
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be described.
[0022] Referring now to the inside of burner
100 and with particular reference to Figures 2A, 23 and 2C,
the burner head 140 is connected to the burner tube 112 by
curved tubing 142 (Figure 2C), conveniently being the same
diameter as the burner tube 112. The burner tube 112 has a
first plurality of holes 143 located about the circumference
of the burner tube 112 at the end of the burner tube 112
distant from the nozzle 102. Likewise, a second plurality
of holes 144 is located about the circumference of the
burner tube 112 at the end of the burner tube 112 located
closer to the nozzle 102.
[0023] The counterflow chamber 150 (best seen
in Figure 2C) is located around the circumference of the
burner tube 112 and extends a distance somewhat greater than
the distance between the first and second plurality of holes
143, 144. The counter flow chamber 150 is joined to the
front plate 160 by welding. The counterflow chamber 150 is
preferably a sealed chamber defined at its distance end by
counterflow chamber intake member 151 such that the
combustion air traveling through holes 161(Figure 23) to the
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burner head 140 does not adversely affect the operation of
the combustion within the counterflow chamber 150. However,
by allowing a certain amount of external air to enter the
counterflow chamber 150, combustion within the counterflow
chamber 150 may be adjusted which can be desirable under
certain operating conditions.
[0024] An air chamber 105 (Figures 2A and 2B)
is in the form of an enclosure defined by front plate 160,
an end plate 116, two side walls 106, 107, a bottom plate
108 (Figure 3C) and a top plate 109. The air chamber 105
surrounds the counterflow chamber 150 and accepts the air
entering the burner 100 through the counterf low air intake
holes 162 (Figures 2A and 28) and securely conveys this air
to the entrance holes 145 (Figures 28 and 2C) of the
counterflow chamber air intake member 151 as indicated by
the arrows 156 in Figure 2B.
[0025] The counterflow chamber air intake
member 151 (Figure 2C) is mounted around the burner tube 112
and forms the end of counterflow chamber 150. A counterflow
ring 163 (Figures 2C and 3C) extends around and is
concentric with the burner tube 112. It is positioned over
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the first plurality of holes 143 as seen in Figures 3A, 3B
and 3C. The ring 163 is used to keep the counterflow flame
from extinguishing when the extent of the flame is changed
by way of air output from the compressor 101 and/or the
combustion fan 111.
[0026] The entrance holes 145 in air intake
member 151 are positioned around the circumference of the
counterflow ring 163 (Figure 2B).
[0027] A flame suppressor 164 (Figure 2C) is
provided around burner tube 112 to prevent the flame in
counterflow chamber 150 from reaching the second plurality
of holes 144 and re-entering the burner tube 112 which could
otherwise cause re-ignition in the burner tube 112.
[0028] The front plate 160 (Figures 2B and 5A)
has a series of holes 161, 162 extending therethrough for
inletting combustion air. Holes 162 admit air to be
circulated through the counterflow chamber 150 (Figure 2C).
Holes 161 admit air used for combustion by the flame on the
burner head 140. The flow of air is best illustrated
diagrammatically in Figure 2B with the air flow for the
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counterflow chamber 150 being indicated by numeral 156 and
the air for the burner head 140 being indicated by numeral
170.
[0029] The nozzle tube 114 (Figure 2C) is
operable to hold the igniter tube 152. An igniter 141 is
mounted within the igniter tube 152 and is positioned within
the nozzle tube 114 such that it extends to the outer
portion of the air-fuel mixture emanating from the nozzle
102. The timing of the igniter 141 is controlled by the
control board 120 (Figure 1) as will be described.
OPERATION
[0030] In operation, the ON-OFF switch 132
(Figure 4) will be set to ON by the user. This initiates
the operation of the combustion fan 111 (Figure 1), the fuel
pump 103 and the igniter 141 within the igniter tube 152
(Figure 2C). It also initiates operation of the warmup LED
134 (Figure 4) to indicate the status of the burner 100
during the startup transitions. A ten(10) second delay is
built into the startup sequence to allow the igniter 141 to
reach operating temperature. After the ten(10) second
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delay, the combustion fan 111 shuts down for three(3)
seconds to terminate air flow over the igniter 141 and to
thereby allow the igniter 141 to reach an increased
temperature prior to fuel ignition.
[0031] The combustion fan 111 (Figure 1)
provides combustion air to the nozzle tube 114 (Figure 2C)
through holes 113 which then passes to the burner tube 112
to support combustion of the fuel (Figures 28 and 2C) within
the burner tube 112. The combustion fan 111 also provides
air through the holes 161, 162 (Figure 22) to supply
combustion air to the burner head 140 and to the entrance
holes 145 in the air intake member 151 for the counterflow
chamber 150. After the three(3) second delay, the
combustion fan 111, the compressor 101 and the fuel pump 103
are activated. The control board 120 is programmed to set
the output of compressor 101 and the output voltage of
combustion fan 111 to the appropriate values during the
startup phase to better control any smoke which may be
produced during startup. Such programming is done depending
on the operating altitudes and operating temperatures where
the burner 100 is located.
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[0032] With reference now to Figures 2C and 3A
and under the influence of the compressor 101, the nozzle
102 sprays a fine mist of fuel and air into the burner tube
112 which will combust with the added combustion air and
form a burner tube flame 153 within the burner tube 112.
Flame 153 will travel through the burner tube 112 and
emanate from the burner head 140, supported by the
combustion air 170 directed to the burner head 140 (Figure
2B) by combustion fan 111 and by ambient air. The force of
the fuel spray from the nozzle 102 will form a small suction
at the inlet of the burner tube 112 thereby setting up a
slightly negative pressure within counterflow chamber 150
via holes 144. Vapor from the burner tube 112 will leave
the burner tube 112 via first plurality of holes 143 and
when the vapor contacts the combustion air provided by
combustion fan 111 entering the counterflow chamber 150
through holes 145 (Figure 2C), it will combust within the
counterflow chamber 150 and form a flame shown
diagrammatically at 154 in Figure 3B. The flame 154 is
deflected and guided by the counterflow chamber ring 163 so
that it heats the burner tube 112 which needs to be hot
enough to allow the formation of the required vapors from
the fuel-air mixture passing through the burner tube 112
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during the vapor flame phase. The ring 163 will also
prevent the counterflow chamber flame 154 from being
extinguished by the flow of combustion air from the
combustion fan 111 in the counterflow chamber 150 and the
flow of the air/fuel vapor mixture coming out of holes 143
due to the pressure generated in the burner tube 112 by the
compressor 101 and combustion fan 111.
[0033] Referring to Figure 3C, the burner 100
is shown in its normal operating mode with the counterflow
chamber flame 154 maintaining the burner tube 112 at an
elevated temperature sufficient to create vapor from the
fuel-air mixture entering the burner tube 112. Once this
fuel-air mixture turns into vapor after extinguishing the
flame 153 in the burner tube 112, a portion of the vapor
enters the counterflow chamber 150 through the holes 143 as
described. The vapors within the burner tube 112 will also
flow to the burner head 140 where they form a flame 155 on
the burner head 140 with the addition of the combustion air.
[0034] The combustion air 156 needs to be of a
volume to allow clean burning of the vapor in the
counterflow chamber 150 which keeps the burner tube 112 hot
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enough to create vapors to burned on the burner head 140.
[0035] The flame suppressor 164 (Figures 2C and
3B) prevents the flame 154 from the vapor combustion within
the counterflow chamber 150 from reentering the burner tube
112 through the second plurality of holes 144 extending
through the burner tube 112 adjacent the nozzle 102 (Figure
2C) and reigniting a flame 153 in the burner tube 112.
[0036] To ensure proper establishment of the
vapor flame phase illustrated in Figure 3C, the compressor
101 and combustion fan 111 are set to operate at
predetermined values by the control board 120 (Figure 1).
These settings are obtained usually by manual trial and
error according to the location of the burner 100 and the
altitude at which it is operating. The igniter 141 will
remain on for a period of approximately thirty(30) seconds
and when power to the igniter 141 is terminated and the
outputs of compressor 101 and combustion fan 111 are
adjusted, the flame 153 within the burner tube 112 is
extinguished by the gases from the counterflow chamber 150
entering the burner tube 112 and also by reducing the
quantity of combustion air from combustion fan 111 and
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changing the air/fuel ratio. The burner tube 112 is at a
temperature where the atomized air-fuel mixture emanating
from the nozzle 102 is converted to vapor or gas by the
elevated temperature of the burner tube 112 which is
maintained by the combustion of the vapor and the creation
of the flame 154 within the counterflow chamber 150 (Figure
3B). With the establishment of a satisfactory flame 154
within the counterflow chamber 150 (Figure 3C), the non-
combusted vapors created by the heating of the burner tube
112 with the flame 154 in the counterflow chamber 150 will
proceed to the burner head 140 where they will combust into
flame 155 on the burner head 140 by the increased air
supplied by the ambient surroundings and also by the
adjustment of the combustion air provided by the combustion
fan 111. The indicator light 134 will stop flashing under
the direction of control board 120 when the normal operating
mode of the burner 100 is reached as illustrated in Figure
3C and will assume a solid color to indicate that the normal
operating mode of the burner 100 has been reached.
[0037] After the normal operating mode of
Figure 3C is reached, the air supplied from the compressor
101 and the combustion fan 111 may be adjusted by way of the
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rotary dial potentiometer 133 (Figure 4). This
adjustment
allows the air-fuel flow and combustion air to increase or
decrease and thereby allows the BTU heat output of the
burner 100 to be varied as may be desired by the user.
[0038] Following the desired operation duration
of the burner 100, the ON-OFF switch 132 is turned off to
terminate operation of the burner 100. The operation of the
igniter 141, the air compressor 101, the fuel pump 103 and
the indicator light 134 terminate. A two(2) minute purge
period requires the cooling fan 122 and the combustion fan
111 to remain on to dissipate fuel vapors within the burner
100 and to cool the components. The cooling fan 122 and the
combustion fan 111 further remain on for a cool down period,
conveniently being about twenty(20) minutes, to dissipate
any vapors remaining in the burner 100 after shutdown and to
more quickly allow the burner 100 and the various electronic
and mechanical components to cool. Following the cool down
period, the cooling fan 122 and the combustion fan 111 will
also shut down. The burner 100 is then quiescent until
further operation of the burner 100 is desired by the user.
[0039] It will be appreciated that the timing
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sequences described above in association with the start up
and shut down of the burner 100 may readily be modified and
that the sequences lend themselves to automation through
changes to the control board 100. Likewise, the voltages
applied to the various fans and compressors may be increased
or decreased to vary the performance of those components,
likewise through changes made to the control board.
[0040] To prevent any potential "flash back" on
the burner head 140, a flame sensor 181 may be conveniently
positioned within the burner head 140 as seen in Figure 6.
This sensor 181 will immediately terminate operation of the
burner 100 if a flash back flame is detected within the
burner head 140. In a further embodiment, if the sensor 181
senses a flame within the burner head 140, it can quickly
initiate a sequence to again start the vapor flame on the
burner head 140 without the necessity of restarting the
start up sequence. In such an embodiment, time is saved for
the restoration of the vapor flame.
[0041] Although the burner head 140 has been
found to operate in a satisfactory manner with no inner
baffle added to the burner head 140, it has been found that
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the addition of an inner and concentric baffle 171 (Figure
6) is beneficial. The concentric baffle 171 preferably has
perforations 172 extending from its inside diameter to its
outside diameter. The use of the baffle 171 has been found
to increase mixing of the fuel vapor emanating from the
burner 100 into the burner head 140 and the combustion air.
CO has therefore been found to be reduced substantially.
[0042] A further flame rod 173 is positioned
outside the burner head 140 as also seen in Figure 6. The
use of a flame rod 173 allows the burner 100 to sense the
presence of the flame 155 (Figure 3C) on the burner head
140. In operation, the flame rod 173 will be positioned
where the initial combustion flame from the burner head
finally completely surrounds the burner head 140 after
startup. Thus, when the flame rod 173 senses the flame on
the burner head 140 after start up of the burner 100, it
will instruct the control board 120 to immediately proceed
with the vapor flame phase of operation thereby also saving
significant time during startup. In the event no flame is
sensed by the flame rod 173, operation of the burner will
terminate under the operation of control boar 120. This is
a safety precaution.
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[0043] To allow a complete sealing of the
burner 100 within an appliance in which it is used, a
sealant member (not illustrated) may conveniently be
positioned on the top of the case 123. The burner 100 may
then be firmly sealed within the appliance (not shown) by
bringing the sealing member into contact with the appliance
to prevent the egress of heated air and to prevent the
ingress of ambient air to the burner 100.
[0044] Many further modifications will readily
occur to those skilled in the art to which the invention
relates and the particular embodiments described herein
should be taken as illustrative of the invention only and
not as limiting its scope as defined in accordance with the
accompanying claims.
