Note: Descriptions are shown in the official language in which they were submitted.
10~041~
The present invention relates to an apparatus for
feeding to a burner equipped furnace a powdery
catalyst mixture. In particular the present invention
is directed to an apparatus for use in existing liquid
or solid fuel burner furnaces, normally comprising one or
more burners.
With the increasing cost of li~uid fuels, attempts
are being made to utilize solid fuels, such as coal,
with chemical c~talyst mixtures. It is known
from prior art to utilize solid fuel hurners. Reference may
be had for instance to U.S. Patent 3,894,834 issued July 15,
1975 to James W. Estes, or to U.S. Patent 3,463,599 issued
August 26, 1969 to A.B. Welty, Jr. The latter reference
shows that it is also known from prior art to combine solid
fuel combustion means with liquid fuel burners, in this
particular reference for the purpose of burning excess
oxygen in fluid gas produced by solid fuel burners. Further
relevant prior art is represented by U.S. 3,291,182 issued
December 30, 1966 to I.A. Dow, Jr. et al and U.S. Patent -~
1,164,139 issued December 14, 1915 to C~V. Stuart.
~he present invention relates to the art wherein
powdery catalyst mixture i added to the flame cone of a
furnace in ordex to achieve a more perfect combustion reaction
to thus reduce fly ash handling, tube blowing time and stack
temperature.
The use of powdery combustion catalysts (e.g. CO-M~TE-
trade namP of Atlantic Combustion Products Limited) in burner
furnaces is known. Normally, the catalyst i~ added, in
relatively small volumes (less than lkg per 10 m2 of heating
surface per 24 hours) by adding the catalyst into the coal
hopper, by spreading same into the combustion chamber at
shut-down times. On boilers working to capacity at all tlmes,
,
lOS041~
the application is normally split into two or three
applications per 24 hours. The known methods are inconvenient
and give rise to difficulties in achieving a uniform feed
of the small volume of the catalyst over a relatively long
period.
It is an object of the present in~ention to provide
a relatively inexpensive apparatus for controlled adding of
a powdery catalyst to a burner furnace. Another object
of the present invention is to provide an inexpensive
device of the above type which is particularly suitable as
an addition to already existing furnaces. A still further
object of the present invention is to provide a device
wherein the appropriate, relatively small volume of
the catalyst is continuously and selectively adjustable solely
by adjusting the speed of mechanical portions of the catalyst
feeding device.
According to one aspect of the present invention,
an apparatus is provided for feeding to a burner equipped
furnace a mixture of a powdery catalyst and air, said - -
apparatus comprising, in combination:
a mechanical feeding device including hopper means
for the catalyst, and mechanical conveyor means for conveying
said catalyst from said hopper means to aischarge means
of said mechanical feeding device; said discharge means being -
coincident with an open ended upstream end of suction conduit
means, the downstream end of said suction conduit means
communicating with suction inducing means disposed in an air
in~ection conduit; said air injection conduit being arranged
to become secured to and to pass through a wall of said
furnace such that an o~tlet orifice of the air injection
conduit can be located within 6aid furnace at an injection
: ~`
-- 2 --
~0S()4~L~
point closely axially spaced from a ~urner of said furnace
and generally coincident with the flame cone of said burner: !
and means for inducing air flow through said air injection
conduit.
According to another aspect of the present invention
apparatus is provided for adding to a burner equipped furnace
a powdery mixture of comminuted combustion catalyst and air
additional to the air-fuel mixture supplied to the burner or
burners of said furnace, said apparatus comprising, in com-
bination, a mechanical feeding device including hopper means
for said catalyst and mechanical conveyor means for conveying
said catalyst from said hopper means to a discharge end of said
mechanical feeding device; said discharge end being coincident
with an open ended upstream end of suction conduit means, the
downstream end of said suction conduit means communicating
: with suction inducing means disposed in an air injection conduit;
said air injection conduit being secured to and passing through
a front wall of said furnace at a location spaced radially
from an associated burner supported by said front wall, to
define a generally straight injection pipe section extending
~20 interiorly of said furnace at an acute angle relative to the
axis of said associated burner; the free end of said pipe
section forming an outlet orifice closely spaced from said
burner and being generally coincident-with the surface of
the flane cone normally generated by said burner.
According to a still further aspect of the present
invention, a liquid burner furnace is provided of the type
comprising at least one liquid fuel burner secured to a wall
of said furnace for projecting a fuel-air flame in a divergent
generally conical pattern into said furnace; and an auxiliary
feeding device for adding to said furnace a powdery mixture of
a combustion catalyst, said feeding device comprising:
-- 3 --
lOS04~
an air injection con~uit secured to and passing through
said ~all, the discharge end of said conduit being spaced
axially inwardly of said furnace relative to said burner and
being generally coincident with the surface of said generally
conical pattern at a point closely spaced from said burner;
said conduit being of the type of a generally straight pipe
having an inlet end disposed exteriorly of said furnace and
provided with air injecting means; said air injecting means
being operatively connected to an outlet of a suction conduit
the inlet of said suction conduit being disposed at a discharge
end of mechanical feeding conveyor means, said conveyor means
forming a part of a mechanical feeding device including
hopper means within which a feeding end of said conveyor means
.
is disposed; and air passage means disposed at the inlet of
said suction conduit means and communicating said suction
conduit means with atmospheric air; whereby said powdery
catalyst i8 fed into said air injection conduit solely by
the suction induced by said air injecting means.
The device according to the present invention further
includes control means for selectively adjusting the rate of
volume of the catalyst discharged at the upstream or inlet end ¦
of the suction conduit. The control means is preferably of
the type of speed control means for governing the speed of the ~ -
conveyor. In a preferred embodiment the conveyor is a screw
conveyor and the speed control means is a variable speed gear
box disposed between the screw conveyor and a drive motor.
Preferably, the mechanical feeding device comprises agitator
means disposed within the hopper means and operative to prevent
the bridging of the catal~st.
The suction inducing means is preferably an air
injector.
The invention will now be described in a greater
-- 4 --
-
~OS04:1~
detail with reference to the accompanying drawings in which;
Figure 1 is a simplified diagrammatic plan view,
partly in section, showing a part of a liquid fuel bu~ner
furnace equipped with the apparatus of the present invention;
Figure 2 is a schematic side view showing the general
arrangement of one example of a mechanical feeding device for
use in the present invention;
Figure 3 is a detail, in section, of part 17 as viewed
in Figure 1
Figure 4 is a perspective view showing the arrangement
of the suction conduit for use in the present invention;
Figure 5 is section V-V of Fiyure 4;
Figure 6 is a detail VI of Figure 1, showing the
geometry of the discharge outlet of the apparatus of the present
invention relative to the associated burner of the furnace.
Turning now to the drawings and ln particular to
Figure 2, a base 1 supports a drive motor 2 whose output end
is connected to the input end of a variable speed gear box 3
having an output shaft 4 connected, by a coupling 5, to a
conveyor screw 6 located at the bottom of a hopper 7. An
intermediate shaft 8 disposed between the coupling 5 and the
conveyor screw 6 is provided with a sprocket gear 9 engaging
. a chain 10 which is further engaged with a large diameter
- sprocket 11 fixedly secured to one end of a shaft 12 provided
with a plurality of stirring arms 13 disposed within the hopper
7, to prevent the bridging of the powdery catalyst material
in the hopper.
Fixedly secured to the end of hopper 7 opposite to
that of the sprocket gear 9 is a bearing housing 14 which
.receives one end of the shaft of the conveyor screw 6, as best
seen from Figure 5. The fixing of the bearing housing 14 to the
.
.~
- 5 -
.
10~04~
the end wall of hopper 7 is effectea by fixedly securing the
housing 14 to a trough-shaped container 15 whose top is open
at 36 in proximity to the adjacent end of the conveyor screw
6 as best shown in Figure 4.
- Figure 5 shows that the trough-shaped container 15
is in a permanent communication with one end of a suction
conduit 16. The opposite, downstream end of the conduit 16
communicates with suction side of an air injection 17 whose
disposition is best seen in Figure 3.
The injector is of a well known structure including
a generally T-shaped housing composed of a combining tube 27
and a delivery tube 28 disposed perpendicularly to the
combining tube 27. A pressurized air conduit 29
passes through an inlet end 30 of the delivery tube
28, to terminate at an air nozzle 31 at a point axially :~
spaced from a discharge end 32 of the delivery tube 28
the discharge end 32 communicating with the inlet of an air
injection conduit 19. The pressurized air conduit 29 is
connected to a source of pressurized air of any suitable type,
in the emhodiment shown, with a pressure air tank 35 (Figure 2)
in which is stored compressed air at a suitable pressure. The -
system may be provided with known air pressure control means
such as a pressure control valve 34 shown in Figure 2.
Normally, the pressure within the air pipe 18 is maintained
at about 80 psi to about 120 psi, depending upon the pressure
within the furnace 21, to secure the generation of an appropriate
suction effect at the combining tube 27 of the air ihjector 17.
As mentioned above, the outlet or discharge end of the
air injector 17 communicates with the air injection conduit
19 passing through a wall 20 of a furnace 21. The air injection
conduit lg is preferably straight and terminates at an outlet
point 22 which is spaced from the associated burner 23 such
- 6 -
.
,
- . . .
losa4~
that the point 22 is spaced slightly axially inwardly relative
to the orifice of burner 23 and is generally coincident with
the surface of a flame cone 24 generated by burner 23. The
term "generally coincident with flame cone 24" in this context,
of course, means that the orifice or nozzle 22 is located
slightly radially outwardly off the surface of the cone such
as to utilize the suction generated by the cone 24 for
inducing a suction assisting in removal of the catalyst
mixture coming from the nozzle 22.
The burner 23 is a regular bunker oil firing burner
whose structure and configuration is well known in the art.
Therefore, the ~urner and its associated parts suffice to be
shown in schematic way as in Figure 1 or in Figure 6.
An exam~le of the arrangement of a burner 23 relative
to the air injection unit is shown in Figure 6. In this
arrangement, the buxner 23 is secured in a known way to a
front wall 20 together with the outlet end section of the air
injecting conduit 19. The burner 23 is of the type having
flame apex angle a of about 45 as shown. The end section
of the conduit 19 is convergent relative to the axis A of
; the flame cone, at about 12 with the orifice or outlet 33
(which is coincident with the aforesaid outlet point 22) being
very closely spaced outwardly of the flame cone, in proximity
; to the burner 23. Such arrangement is of advantage as it
- utilizes the effect of the flame and air vacuum at the outlet
33 to thoroughly disperse the catalyst powdèr delivered by pipe 19,
to thus achieve a virtually complete reaction of the combus-
tion. The pipe 19 in the embodiment shown is a heat resistant
pipe made of standard stainless steel schedule 40, the pipe
having 1-1/2" I.D. Its length ~from injector 17 to orifice 33) :
is about 3 feet. ~ :
-- 7 --
'~ ' '
105V41;~ ~
In operation, the burner 23 is first started. Pressure
air valve 34 is adjusted to maintain a predetermined pressure
in the pipe 29, as referred to above. The vacuum genera~ed
in the injector produces air draw through the opening 36 in
the trough-shaped container 15 and through the suction condui~
16. The motor 2 is then actuated to drive the conveyor screw
such as to discharge th2 powdery catalyst into the trough-
shaped container 15, through the opening 36. The induced air
suction conveys the catalyst ~rom the container 15 to the combining
tube 28 of the air injector 17, wherefrom the catalyst is forced
by the air flow to enter the air iniection ~onduit 19 to
eventually become discharged at the orifice or outlet 33O If it
is desired to change the volume of the catalyst at the outlet 33,
the gear box 3 is operated to change the speed of the screw 6
with the resulting change in volume of the catalyst discharged
into the trough-shaped container 15.
The advantage of the present invention over prior
art resides particularly in that the invention provides
relatively inexpensive means for an appropriate, fine adjustment
of the ratio of the catalyst mixture solely by mechanical
means, i.e. by appropriate control of the speed of the
conveyor screw 6. The device is easily applicable for use in
existing burner furnaces.
It will be appreciated that many modifications
of the embodiment described above are possible. For instance,
the size or type of the mechanical feeding device will, of
course, depend on actual operational conditions, of the
thickness of furnace walls, etc. The exact location,
disposition and size of the pipe 19 will obviously differ
3~ depending on the type of the furnace. These and many other
modifications of the described embodiment, however, do not
depart from the scope of th~ present invention as defined
b in the accompanying claims.
8 -
,
: , ' '' " ' ' '' `
