U.S. patent number 3,765,820 [Application Number 05/285,376] was granted by the patent office on 1973-10-16 for combustion apparatus.
This patent grant is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Koji Ito, Toshio Ito, Tamotsu Nomaguichi, Masahiro Sakai.
United States Patent |
3,765,820 |
Ito , et al. |
October 16, 1973 |
COMBUSTION APPARATUS
Abstract
Combustion apparatus having a luminous element disposed within,
and projecting above, a combustion plate. The light emitted by the
luminous element, which will depend upon the state of combustion,
is detected by a light detector, which through appropriate
electronic circuitry containing various electronic components, will
operate to control the air supply to the combustion housing whereby
a proper combustible mixture for stable combustion is constantly
being maintained. In like manner, the fuel supply may be
controlled, in lieu of controlling the air supply.
Inventors: |
Ito; Toshio (Hyogo-ken,
Amagasaki, JA), Nomaguichi; Tamotsu (Hyogo-ken,
Amagasaki, JA), Sakai; Masahiro (Hyogo-ken,
Amagasaki, JA), Ito; Koji (Hyogo-ken, Amagasaki,
JA) |
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha (Tokyo, JA)
|
Family
ID: |
11803984 |
Appl.
No.: |
05/285,376 |
Filed: |
August 31, 1972 |
Foreign Application Priority Data
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Feb 3, 1972 [JA] |
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47/12392 |
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Current U.S.
Class: |
431/75;
431/79 |
Current CPC
Class: |
F23N
5/082 (20130101); F23D 14/725 (20130101); F23N
2233/08 (20200101); F23N 5/08 (20130101) |
Current International
Class: |
F23D
14/72 (20060101); F23N 5/08 (20060101); F23n
005/08 () |
Field of
Search: |
;431/75,79,89,328 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Favors; Edward G.
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. Combustion apparatus comprising:
a fuel supplier for supplying fuel to said combustion
apparatus;
an air supplier for supplying air to said combustion apparatus;
a mixing chamber for mixing said fuel and air supplied to said
apparatus;
a combustion plate for igniting said fuel and air mixture within a
combustion chamber;
a luminous element disposed within said combustion plate, said
luminous element emitting light in an amount which is directly
proportional to the amount of heat of combustion received by said
element;
a light detector for detecting said light emitted from said
luminous element; and
a control means electronically connected to said light detector for
controlling the amount of air supplied by said air supplier.
2. Combustion apparatus as set forth in claim 1, wherein said
combustion plate contains a plurality of flame holes and separates
said mixing chamber from said combustion chamber, and wherein said
luminous element projects from said plate into said combustion
chamber.
3. Combustion apparatus as set forth in claim 1, wherein said
control means comprises:
an amplifier for amplifying a signal emitted by said light
detector;
a thyristor short angle control circuit for receiving said
amplified signal; and
a bidirectional thyristor for receiving a signal from said
thyristor short angle control circuit for controlling the electric
current of an AC power source which in turn electronically controls
said air supplier.
4. Combustion apparatus as set forth in claim 2, wherein said
control means comprises
an amplifier for amplifying a signal emitted by said light
detector;
a thyristor short angle control circuit for receiving said
amplified signal; and
a bidirectional thyristor for receiving a signal from said
thyristor short angle control circuit for controlling the electric
current of an AC power source which in turn electronically controls
said air supplier.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to combustion apparatus and
more particularly to an improved combustion apparatus for
stabilizing the flame of combustion within the combustion
chamber.
2. Description of the Prior Art:
One type of combustion system which has been widely employed in
combustion apparatus is the diffusion combustion system, practical
embodiments of which may include gun type combustion apparatus, pot
type combustion apparatus, and red flame type combustion apparatus
utilizing gas combustion. In these combustion systems, the
concentration of fuel, from 100 to 0 percent fuel, has been
dependent upon the atmosphere of combustion, so that the stability
of the combustion has been remarkably high, which has accounted for
the adoption of such systems of combustion in various fields.
However, such systems have serious disadvantages, in that, for
example, it is possible to attain incomplete combustion as a result
of improper mixing of fuel and air. If, for example, the fuel is
introduced into the combustion atmosphere when the mixing of the
fuel and air is incomplete, the fuel component will be thermally
decomposed so that only a portion of the fuel component will be
burnt while the remainder results in the formation of soot.
Consequently, although soot causes an increase in heat transmission
from the combustion gases, at the same time, it also causes
pollution of the air by increasing the percentage of carbon
monoxide and nitrogen oxide.
One system which has been proposed as a method of eliminating the
disadvantages of the diffusion combustion system is that system
which prepares a primary gas mixture of fuel and air, such system
resulting in a significant decrease in the formation of soot.
However, such a system has also been plagued with serious problems,
such as, for example, in attaining optimum concentration of fuel
and air within the primary gas mixture and of maintaining the
stability of the flame of combustion while altering the fuel-air
concentration.
Such problems are particularly concerned with the velocity of
combustion and the fuel supply velocity. When, for example the fuel
supply velocity is greater than the velocity of combustion, the
flame is blown downstream, such phenomenon being known as a blown
extinguishment. Similarly, when the fuel supply velocity is less
than the velocity of combustion, the flame is sucked back into the
flame holes, thereby causing a backfire. Complete combustion is
thus impossible to attain and combustion is therefore intermittent
whenever blown extinguishment or backfire occurs. Accordingly, it
is desirable and necessary to prevent this unstable condition from
occurring. Obviously, then, in order to maintain the stable
condition of combustion, it is necessary to maintain the fuel
supply velocity at a level which is less than the velocity,
relative to the velocity of combustion, at which blown
extinguishment occurs, but which is greater than the relative
velocity at which backfire occurs. In addition, although the fuel
supply velocity may be within the range for obtaining proper and
complete combustion, combustion noise may be caused for some values
of fuel supply velocity. Accordingly, it is also necessary for the
fuel supply velocity to be without the range of velocities at which
combustion noise will be produced.
Furthermore, at the optimum operating conditions for the combustion
apparatus, the excess amount of air will be minimized for easily
heat-exchanging the combustion air and the combustion gas.
Likewise, complete combustion without the formation of soot, and
stabilization of the flame of combustion, will similarly be
attained. Accordingly, the unstable conditions of the flame of
combustion occur when the optimum operating conditions are changed
by external and internal causes. It is also noted however, that it
is necessary to utilize combustion apparatus which is capable of
operation under those conditions wherein a broader range of excess
air will be required and which should be automatically controlled
depending upon the change in operating conditions.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
improved combustion apparatus.
Another object of the present invention is to provide an improved
combustion apparatus which will attain stabilization of the flame
of combustion without the attendant conventional disadvantages.
Still another object of the present invention is to provide an
improved combustion apparatus which will automatically attain
proper mixing of fuel and air under unstable combustion conditions
so as to ultimately attain stable combustion.
Yet another object of the present invention is to provide an
improved combustion apparatus which will prevent the occurrence of
backfire or blown-extinguishment, and which will also eliminate a
substantial portion of the attendant noise of combustion.
The foregoing objectives are achieved according to this invention
through the provision of combustion apparatus which employs a
luminous element disposed within, and projecting above, the
combustion plate. The light emitted by the element, depending upon
the state of combustion then present, is detected by a
light-detector, which, through appropriate electronic-circuitry
containing various electronic components, will control the amount
of air supplied to the combustion housing. In this manner, if the
state of combustion should approach either of the extreme unstable
conditions, that is, back-fire, or blown-extinguishment, the air
supply will be automatically adjusted so as to return the apparatus
to stable combustion operation. In lieu of controlling the air
supply, the apparatus may be utilized so as to control the fuel
supply.
BRIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood from the following detailed description
when considered in connection with the accompanying drawings, in
which like reference characters designate like or corresponding
parts throughout the several views and wherein:
FIG. 1 is a schematic scetional view of one embodiment of a
combustion apparatus constructed according to this invention and
showing its cooperative parts; and
FIG. 2 is a schematic view of the control means for controlling the
air supply of the combustion apparatus illustrated in FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings and more particularly to FIG. 1,
there is shown a combustion apparatus, generally indicated by the
reference character 1 comprising a cylindrical combustion housing 2
having transversely disposed therein a combustion plate 3 which,
having a plurality of flame holes, serves as a buyner. A luminous
element 4, which may be, for example, a platinum wire, is fitted
within, and projects above, combustion plate 3. The location of
plate 3, relative to housing 2, divides housing 2 into a lower
mixing chamber 5 for mixing fuel and air, and an upper combustion
chamber 6. A light detector 7, which may be, for example, a CdS
photoelectric element, is connected to the combustion housing 2 at
a point such that it can detect light emitted from luminous element
4.
Referring now to FIG. 2, the control means for controlling the air
supply of the combustion apparatus is shown in detail. A light
detecting means 8, including light detector element 7, is
electronically connected to a controller 9 which controls the air
supply to be delivered to the combustion housing 2. Controller 9,
which is generally indicated by the dotted outline portion,
comprises an amplifier 10 for amplifying the signal from detecting
means 8, a thyristor short angle control circuit 11 and a
bidirectional thyristor 12 for controlling the electrical output of
an AC power source 13. An air supplier 14, such as, for example, a
blower, is electronically controlled by source 13 while an air duct
15 is provided for conducting the air supplied by blower 14 to the
combustion housing 2. A fuel supplier 16 for supplying fuel to the
combustion housing 2 is likewise provided, the fuel being conducted
to housing 2 via fuel supply pipe 17.
In operation, when combustion which has been in a stable condition,
is altered by any one of various cases so as to approach a
back-fire condition, wherein the flame of combustion will be upon
the surface of the burner 3,the platinum wire 4, fitted upon the
surface of the burner 3, will be heated and become luminescent. The
platinum wire 4 thereby provides light which is distinguished from
that of the flame, and the change in the light emitted by the
platinum wire is received by the CdS photoelectric element 7 which
results in the inner resistance of the CdS photoelectric element 7
being decreased so as to increase the electric current being passed
through element 7. This change in current flow is then amplified by
amplifier 10, which parameter is then fed to the thyristor short
angle control circuit 11 so as to decrease the short angle of the
bidirectional thyristor 12. The rotary speed of the blower 14 is
consequently increased, and an excess of air is supplied so as to
stabilize the combustion flame.
At the other extreme, when combustion approaches the state in which
the flame of combustion could be blown extinguished, the flame is
located above the surface of plate 3 whereby the wire 4 is not
heated and consequently its temperature and light emission
decreases. It is thus seen that the light emitted is directly
proportional to the heat of combustion received by the element. The
resistance of the CdS photoelectric element 7 is thereby increased
causing the electric current passing through element 7 to be
decreased. After passing through amplifier 10 and control circuit
11, the resulting current causes the short angle of the
bidirectional thyristor 12 to be increased so as to decrease the
rotary speed of the blower 14. This in turn reduces the excess
amount of air being supplied, which results in the lowering of the
flame and its ultimate stabilization. This stable condition of
combustion can thus be automatically maintained by repetition of
these operations should the combustion become unstable at any
instant of time. In conjunction with such operations, it is noted
that the maximum and minimum limits of the short angle may be
determined by the resistance of the control circuit 11. In
addition, the resulting change in the flame of combustion will not
be instantaneous due to the large moment of inertia of the blower
14. However, the changes in the flame of combustion will be rapid
enough in order that the extreme unstable conditions of combustion,
that is, back-fire, or blown-extinguishment, will not be
attained.
In an experiment performed with the apparatus of the present
invention it was possible to operate the apparatus in its stable
condition within the range of .+-. 50 percent of the change in the
amount of fuel supplied to the combustion housing. Within the
apparatus, although a CdS photoelectric element may be used as the
light detector, it is also possible to use other photoelectric
elements such as, for example, a photo-transistor, a sun-electric
cell, or the like.
Similarly, although a variable speed blower may be employed as the
control means for controlling the amount of air supplied to the
combustion housing, it is also possible to control the amount of
air supplied, by other means, such as, for example, a control valve
actuated within the air duct 15.
In addition, the mode of operation is not limited to those examples
noted heretofore, and it is entirely possible to control the amount
of fuel supplied to the combustion housing in lieu of controlling
the air supply to the housing, such fuel supply being regulated by
control means similar to those control elements disclosed
heretofore. Accordingly, the present invention provides combustion
apparatus for stabilizing the state of combustion by controlling
either the fuel supply or the air supply being conducted to the
combustion housing.
Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is to be
understood therefore, that within the scope of the appended claims
the present invention may be practiced otherwise than as
specifically described herein.
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