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Патент USA US2409005

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Oct. 8, 1946.
E.‘ G. SMITH
I
2,409,002
METHOD AND APPARATUS FOR SUPPLYING
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PULVERIZED COAL AND AIR TO FURNACES
Filed'June 12, 1945
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METHOD AND APPARATUS FOR SUPPLYING
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Filed June 12, 1943
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Oct. 8, 1946.
E. G. SMITH
2,409,002
METHOD AND APPARATUS FOR SUPPLYING
PULVERIZED COAL AND AIR TO FURNACES
Filed June 12, 1943
4 Sheets-Sheét s
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E. G. SMITH
METHOD AND APPARATUS
FOR
2,409,002
SUPPLYING
‘
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PULVERIZED COAL AND AIR TO FURNACES
‘Filed June 12, 1943
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Patented Oct. 8, 1946
2,409,002
UNITED STATESCPATENT OFFICE
2,409,002
METHOD AND APPARATUS FOR SUPPLYING
PULVERIZED COAL AND AIR TO FUR—
NACES
‘Edwin G. Smith, Mount Lebanon, Pa., assignor,
by mesne assignments, to Union Industries,
Incorporated, Grantsville, Md, a corporation of
Maryland
.
Application June 12, 1943, Serial No. 490,588
5 Claims.
1
This invention relates to a control system for
supplying pulverized solid fuel and air for com
bustion to the burners of one or more furnaces
or other similar fuel-consuming apparatus.
Systems for supplying pulverized solid fuel
(Cl. 110—104)
2
and the various novel features and advantages
thereof may be obtained from the following de-
tailed description and explanation which refer
to the accompanying drawings illustrating .the
preferred embodiment brie?y outlined above. .In
the drawings,
such as coal have been applied heretofore chie?y
Figures 1A and 13 together constitute a
to boiler furnaces particularly in central-station
diagrammatic layout of my system for supplying’
power plants where load conditions are fairly
pulverized solid fuel and air to a plurality of
constant and the fuel may, therefore, be fed at
a substantially uniform rate. It is one object of 10 burners;
I
this invention to provide a control system capable
of supplying fuel such as pulverized coal, and
Figure 2 is a similar view showing the auxiliary
apparatus located adjacent each burner; and
Figure 3 is a similar view showing the con
air to a plurality of furnaces or to a plurality
trol system adapted to an installation including
of burners in a single furnace. Since conditions
may vary materially between the several furnaces 15 a plurality of burners in a single furnace.
Referring now in detail to the drawings and,
or even between the different portions of a single
large furnace, fuel-supply systems known here
tofore are not adapted to this type of installa
tion.
’
for the'present, to'Figures 1A and 13, a plurality
of furnaces ID are provided with burners adapted
for the combustion of pulverized coal, each fur
I have invented a novel system for controlling 20 nace having at least one burner such as indicated
the supply of pulverized coal and air to a plu
at H. The apparatus for supplying fuel and
air to the burners of the several furnaces in
rality of burners by which the fuel and air sup
cludes a main headerv pipe l2 adapted to convey
plied to each burner are individually controlled
a mixture of fuel and primary air to the burners.
in accordance with the conditions existing in the
of the several furnaces. Branch connections l2a
region heated by the particular burner. To ac
extend from the pipe 12 to each burner II. Air
complish this, I deliver pulverized coal to a
is supplied to the pipe l2 by a blower l3 driven
main circulating pipe with a volume of air so
by any convenient means such‘ as a suitable'elec
proportioned as to produce a non-explosive mix
tric motor. A damper [4 controls the volume
ture, and maintain the air under sufficient pres
sure to convey the coal through the pipe. I - of air delivered by the blower to the pipe l2 and,
therefore, the pressure of air in the latter.
provide means for automatically controlling the
A regulator l5 .has a diaphragm chamber con
fuel taken from the main pipe by each burner
nected to the pipe l2 on the downstream side of
in accordance with the temperature existing in
the damper I4 for maintaining substantially
the region heated thereby. I also provide means
for maintaining substantiallyconstant the pres 0a in constant the pressure of the air in the pipe l2.
The regulator includes a swinging nozzle 16
sure of the air in the main circulating pipe and
which operates a valve l1 and a hydraulic motor
means for changing the rate of supplying fuel
I8. The regulator and its associated control
to the pipe according to the demands for fuel
mechanism are all of known construction so a
made by the several burners connected thereto.
I also supply secondary air to the several 40 detailed description thereof is unnecessary. It
is su?icient to state that when the pressure in
burners through a main circulating pipe and
the pipe l2 changes, for any reason, the regulator
control the amount of secondary air supplied
I5 operates the swinging nozzle to supply air
to each burner in accordance with the amount
from a source to which it is connected by a pipe
of fuel delivered thereto.
ita, under suitable pressure, to one of the two
I introduce in the main pipe for circulating
pipes leading to the valve H. The valve is
pulverized coal a variable restriction in order
thus operated to control the supply of- ?uid from
to produce a minimum back pressure when the
burners are being ?red at a low rate. This in
a source to which it is connected by pipe Ila, to
sures that pressure impulses will be generated
the motor iii in such manner as to actuate the
in the pipe on a change in the fuel demand of
damper I4 through a crank l9 and link 20 tov
any burner. I utilize these pressure impulses
cause the pressure in the pipe l2 to be restored .
to operate the various control devices embodied
to ~normal.- The motor. l8 may, as illustrated,
in a completely automatic system according to
comprise a cylinder and piston operating the
my invention.
‘
crank 19 through a rack and pinion.- In a system
. A complete understanding of the invention 55 such as that shown diagrammatically, the regu
2,409,002
3
4
lator I5 is preferably set to maintain a pressure
of about '7" of water in the pipe I2.
Pulverized coal is delivered to the pipe I2 on
the downstream side of the damper I4 from a
storage bin ‘it through a connection 22 by a feeder
quantity suf?cient to effect complete combustion
of the fuel from a header 46. Branch pipes 41
each including a control valve 48 extend from
the header 46 to each burner II, Air is supplied
to the header‘ 46 by a blower 49 through a pipe 50.
The. amount of air supplied by the blower is so
23 having, aivariable-speed drive 24. An. adequate
controlled as to maintain a substantially constant
pressure of air in the header. To this end, the
supply of coal is maintained in the bin 2| by
pressure-switches 25 and 26 which may be of the
diaphragm or other suitable type, controlling. a
inlet of the blower 49 is provided with a damper
starter 2'! for the motor 21a of: a pulverizing mill 10 58a. A pressure regulator 5I similar to that
shown at I5 is. subject to the pressure in the
28. The mill delivers fuel under air blast through
header by virtue of a connecting pipe 52 and
a pipe 29 to a collector 30 above the bin 2|. The
operates a valve-~53 similar to that shown at I1
switch 25 starts the mill when the level of fuel
to- control hydraulic motor 54 for the damper 49a
_ in the bin has fallen to a predetermined point
and the switch 26 stops the mill when the level of '
fuel in the bin has been raised to the desired
height. The pipe I2 extends from, the blower I3.
and the fuel bin 2I to each of the furnaces II]
in turn making a complete circuit thereof and
?nally returning to the bin 2|, A collector 3|
is: disposed in the return portion ofv the pipe as
is alsov a variable restriction 32 of any suitable
construction.
The» amount of fuel delivered to the pipe I2
through the connection 22 .byv feeder 23 is auto
matically controlled in accordance with the
amount of air supplied to the pipe by blower I3.
For this- purpose, a ratio regulator 33 controls
the variable-speed transmission 24- through a hy
draulic motor 34 in the form of a cylinder and
piston; The regulator 33 has a diaphragm in’ a
15
20
25
30
chamber 35' subject, through suitable pipe con
nections 35a; to‘ the pressure on opposite sides
of an ori?ce plate- 361 in the inlet of the blower
I3, The regulator also has a diaphragm in a 35
chamber 3'!" subject by means of a pipe 31a to
thepressure in a compressed air line 38 includ
ing: a constant pressure regulator 38a, as con
the same manner that the motor‘ I8 controls
the damper I 4, The regulator 5| is set to main
tain suflicient pressure in the header 46 to supply
to the burners the amount of air required for
complete combustion of the fuel. While the pres
sure in the header 48 will vary with the individual
conditions of a particular installation, a relatively
low pressure such as between 7" and 16"’ of water
will generally'be found suiiicient.
The amount of secondary air supplied to indi
vidual burners is controlled according to the
amount of‘ fuel supplied thereto, in order to in
sure e?icient combustion at each burner, regard
less: of the ?ring rate. To this end, each valve
48; is provided with automatic control means in
eluding a ratio regulator 55', control valve 55a
and‘ a hydraulic damper-operating motor 55b
similar to those shown at l8 and 54. The regu
lator 55 is similar-toltheregulator 33'. It includes
a chamber 56' having a diaphragm subject by
means: of pipes 56a to the pressures on opposite
sideslof an ori?ceplate 51 in the branch pipe 4'1,
and5 a chamber 58 containing a diaphragm sub
ject to the pressure in a pipe 59 connected
through a regulator 60 to a compressed air line
Gil‘ having a constant-pressure regulator ?lo
therein. The line 5| may be connected to the
same source‘ as the line 38. The regulator 60 is’
trolled by an adjustable regulator 39 connected
40
therein.
The diaphragms in the chambers 35 and 31 are
disposed in opposition and the differential effect
adjusted in accordance with the position of the
thereof operates‘ the nozzle of the regulator to
actuating- mechanism 43» for the fuel valve 42.
control‘ a valve 40 governing‘the motor 34 in the
While any convenient mechanism may be em
same manner that the valve I‘I controls the
ployed for adjusting the regulator 60; I have il
motor I8; A connection 41 from the variable
lustrated diagrammatically a drum 52 mounted
speed drive 24- to the regulator 39 adjusts the lat
for! rotation about a vertical axis, having a heli
ter after- an operation of ' the former to restore
cal slot 63 therein in which the adjusting mem
the regulator 33: to neutral or balanced position.
ber of‘ the regulator 60 rides.- The drum 62 has
In this manner, the regulator 33 controls the. ‘
a cable“ wound. around it and connected to the
amount of coal suppliedlto the pipe l2 in accord‘
crank: arm 43:: of'the mechanism 43-. The drum
ance with the amount of air passing there
621' has a spring or counterweight tending to re.
through. The regulator 33 is preferably adjust
turn— it to starting’ position when the crank arm
edtcmaintain the fuel-air ratio at a value which
swingsiback toward the position it' occupies when
furnishes only about 35%‘ of' the amount of‘ air.
the valve 42 is closed. It will be evident‘ that by
theoretically‘ required for complete combustion.
means. of the mechanism described, the regulatory
With this amount of primary air, the fuel-air
55-is subjected to opposing pressures; one propor
mixture is not explosive.
tionaI to the ?ow of air through the branch pipe
The supply of coal‘ and primary air from the
41‘ and the other proportional to the-flow of fuel.
pipe l-2‘ to the individual burners is regulated by
through pipe I-2-a. The regulator 55 is operated by
control‘ valves 42 in the branch pipes I2a. Each
the differential between‘ the pressures on. the dia
furnace I'll‘ has automatic means for controlling
phragms and shifts its swinging nozzle to. oper
its valve‘ 42, the equipment making up the auto
ate valve 55a which controls the motor 58..
matic control‘ for one furnace being shown in
The method of my invention will doubtless be
detail‘. in Figure 2. As there. shown, the valve
apparent‘ from the foregoing‘ description of the
42 is operated by an actuating mechanism 43
apparatus which Iv prefer to employ in order to,
preferably including an electric motor and drive
obtain‘ automatic‘ operation, but will neverthe
mechanism suitable for swinging a crank arm
less be explained brie?y. For the purpose of‘ ex
43w pivoted to a linkage 43b connecting it to the
valve. A thermo-couple 44‘ at a- suitable point in
plaining my method, it will be assumed that the
system; is in operation under normalv conditions,
the furnace I0 is connected to an automatic tem
the blower I3 and feeder- 23- supplying a non~ex~
perature control 451' of‘ known construction, in
plosive mixture of fuel‘ and air to the pipe I2, the
cluding a relay 45a which directly controls‘ the
individual burner valves 42 being controlled to
motor of the mechanism‘ 43,
Secondary air is supplied' to the burners: II in 75 divert from the pipe I lthe-amount of fuel‘neces
5
2,409,002
sary to maintain the temperature required in the
furnaces, and the'blower 49 operating ‘to furnish
secondary air to the burners under the control
of valves 48 to effect complete combustion of the
fuel. The restriction 32, having been adjusted
to an appropriate position, causes a predeter
mined back pressure to be built up in the pipe
6
are three pairs of burners‘?ring into the furnace,
one burner of each pair being on each side of
the furnace. The three thermo-couples each
control one pair of burners. It will thus be ap
parent that the ‘system shown diagrammatically
in Figure 3 issimilar to that shown in-the other
?gures except that the burners all ?re into one
furnace and are controlled in pairs instead of
individually’. It will be noted that the branch
ments of the several furnace burners are re“ 10 pipes Bl andv 69 are connected to'both burners 66
turned to the bin 2| through the collector‘ 3| and
of each pair which are in alinement on opposite
the proper reserve of pulverized coal is main
sides of the furnace 65. It will be understood
tained in the bin 2| by the switches 25 and 28
thatiin the system of Figure 3, the zone or area
which control the starter for the mill driving the
heated by each pair of burners is controlled by its
I2 between it and the damper I4. Any excess fuel
and air supplied to the pipe I2 above the require
pulverizer. As already indicated, the regulator
own . thermo-couple ‘II
I5 maintains a predetermined constant air pres
sure in the pipe I2. The regulator 5| performs
the same function in respect to the header 4,5 and
other zones or areas. This makes'it possible to
independently of the
maintain a uniform temperature throughout the
furnace or a predetermined temperature radient
the regulator 33 automatically proportions the
longitudinally thereof, if desired.
.
>
_
amount of fuel fed into the pipe I2 according to 20
It will be apparent from the foregoing that my
the volume of air ?owing therethrough.
v’
invention is characterized by numerous important
If the temperature in any one of the furnaces
advantages over methods and apparatus known
I I] should vary from the desired value, for any
previously for supplying pulverized solid fuel to
reason, the controller 45 for that furnace im
burners and controlling the combustion thereof.
mediately operates to shift the fuel control valve
The system of my invention maintainsa con~
42. The shifting‘ of the valve 42 causes a pres
stantly circulating supply of fuel of uniform con
sure impulse to travel back through the pipe i2.
centration in a conveying air stream, the ratio of
If the valve 42 is shifted toward the closed posi
fuel to air being controlled, preferably in about
tion, the pressure in the pipe I2 will be slightly
the ratio of 1 pound of coal to not over 5 pounds
increased. Conversely, if the opening of the valve 30 of air, thereby producing a non-explosive mix
42 is increased, a slight drop will occur in the
ture. The concentration of fuel in the circulating
pressure in pipe I2. In either case, the regula
pipe is controlled automatically at various rates of
tor I5 will operate to shift the damper I4 in the
fuel consumption and air ?ow, as determined by
proper direction to restore the pressure in the
the pressure in the circulating pipe at a point
pipe I2 to its previous value. This will involve a
upstream from that at which fuel is introduced.
change in the amount of air supplied to the pipe
I2 which will be effective through regulator 33 to
adjust accordingly the speed of the feeder 23 and
The invention maintains the fuel-air mixture in
the circulating pipe at substantially constant
pressure, despite variations in the rate of fuel
thus appropriately control the rate at which fuel
consumption.
is fed to the pipe I2.
40 The invention also provides automatically a
Any change in the position of the fuel valve 42
supply of secondary air proportioned to the rate
of any burner thus causes the entire system to
of feeding fuel, for effecting the combustion
be readjusted in accordance with the ?ring rate
thereof with the utmost efficiency.
demanded by the conditions then existing in the
It is to be noted that the fuel is delivered to
furnace in which the burner is installed. Any ” the burners in suspension in low-pressure air
change in the adjustment of the fuel valve 42
and that the fuel does not pass through the
of any burner as indicated above, immediately
blower supplying primary air. The use of a
‘effects operation of the valve 48 controlling the
variable restriction in the circulating pipe as
supply of secondary air to that burner. This re
sures satisfactory operation of the automatic
sults from the connection between the valve-op- " control even at relatively low ?ring rates. The
crating mechanism 43 and the adjustable regula~
invention also provides for maintaining an ample
tor 60 which governs the counter-pressure applied
supply of pulverized fuel for immediate intro
to the regulator 55. The volume of secondary air
duction into the circulating pipe as required by
supplied to the particular burner is thus altered
the demand of the several burners. The de
according to the requirement of the adjusted fuel ' livery of pulverized coal to the storage bin from
supply.
The regulator 5! then controls the
the pulverizing mill is controlled automatically.
damper 49a to bring the pressure in the header
46 back to its normal value.
Figure 3 illustrates the application of my in
vention to a furnace 65 having a plurality of
Although I have illustrated and described but
a preferred embodiment of the invention, it will
be recognized that changes in the details of the
system or its exact mode of application may be
burners 66 ?ring thereinto, the burners being
spaced along opposite sides of the furnace. These
burners are connected to the main circulating
I30
made without departing from the spirit of the
invention or the scope of the ‘appended claims.
I claim:
1. In a method of supplying pulverized solid
pipe I2, shown in a complete system in Figures
1A and 1B, by connections 51 including control ' fuel to a combustion chamber, the steps includ
valves 68. Similarly, connections 69 including
ing circulating primary air through a delivery
control valves ‘HI extend from the secondary air
conduit, injecting the fuel into the air stream
header 46 to the burners. Thermo-couples ‘I I '
through the conduit, diverting a portion of the
spaced along the length of the furnace control
air and fuel from the conduit to the combustion
the valves 68 through operating mechanisms such TI.) chamber, varying the amount of fuel and air
as shown at 43 in Figure 2 and the valves ‘I0 are
diverted in accordance with the temperature in
automatically controlled in accordance with the
said chamber, varying the amount of fuel and air
rate at which fuel is supplied, by the’automatic
supplied to the conduit in accordance with the air
means already described, i. e., the regulator 55.
pressure therein, supplying secondary air to the
In the embodiment illustrated in Figure 3, there
chamber and controlling the amount of sec
I
.ondary T811‘ ‘in proportion to the > amount “of pri
mary "air and fuel supplied.
12. In ;a method of supplying ‘pulverized solid
fuel to a, plurality of burners‘ spaced alongacom
'busti'on chamber the steps including circulating
‘primary vair through a deliveryiconduit, injecting
to a plurallty'oi burners comprising-a container
.forstoring-fu'eLa circulation'jpipe extending :from
said-‘container to said burners in series and are
turning to said container, means for feeding fuel
to said pipe from said container, means for auto
matically controlling .the ‘flow of fuel from the
pipe to the burners'individually, means for sup
plying secondary air to the burners, and means
controlling the input to the secondary air-sup
conduit to each burner in accordance with the
temperature ‘in the chamber adjacent such 11 0 plying means to maintain the pressure of the vsec
fuel :into ‘the air stream through the conduit,
diverting a portion of thefuel and air from the
burner, supplying secondary air to ‘the several
burners, and'controlling ‘the ‘supply of secondary
ondary air substantially constant ‘adjacent the
burners.
5. A system for supplying pulverized solid fuel
air :in accordance with vthe amount of fuel and
to-auseries
of furnaces, each having onerormore
primary air supplied .to said burners.
13. A system for supplying pulverized solid fuel v15 burners, comprising ta container for storing ‘fuel,
a circulation pipe extending from the container
to aplurality'of burners comprising a container
‘for storing fi?l, a circulation pipe jextendingvfrom
to said furnaces and burners in ‘series and re
said ‘container to said burners in series and re
turning tosaidcontainerrmeans for feeding fuel
tioning the amount of fuel supplied to the _:pipe
to the amount of 'air supplied thereto, :as tomain
vtain substantially constant ‘.the ratio ,therebe
controlling the input to the ‘secondary vair-sup
‘to :said pipe . from said container, means'for auto
turning to said container, means for feeding fuel
torsaid pipe from said container, .means for auto 20 matically controlling the flow of fuel from the
pipe to the burners individually, means forsup
matically controlling the l?ow of fuel from the
plying air to said pipe to convey .-fuel to the burn
pipe to :the burners individually, means for :sup
ers, ‘means for automatically ‘proportioning the
‘plying air to ‘the pipe, means controlling the :air
air supplied to theliuel conveyed, means for sup
supply to maintain the pressure insaid pipe-sub
plying secondary air to the burners, and ‘means
stantially constant, "and means for :so gpropor
tween.
4. A ‘system for supplying ' pulverized solid fuel .30
plying means to ‘maintain a predetermined pres
sure therein-and thereby proportion ‘the vamount
of secondary air supplied.
‘EDWIN G. SMITH;
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