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Патент USA US2127445

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Aug. 16, v1938.
Filed March‘ 12, 1955
2 Sheets-Sheet l
Ralph M. Hardgrove.
‘Aug. 16, 1938.
Filed March 12, 1935
2 Sheets-Sheet 2
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Patented Aug. ' 116, 1938 r
Ralph M. Hardgrove, West?eld, N. J., assignor to
Bailey Meter Company, a corporation of Dela
Application March 12, 1935, Serial No. 10.667
4 Claims.
(01. mas-2s)
Another object of the invention is to provide
In connection with the operation of furnaces
and especially furnaces utilizing fuels burned in
suspension, such as oil, gas, or pulverized fuel,
in connection with a furnace having .a plurality
of fuel burners an interlocking arrangement such
the danger exists that in kindling a. ?re an‘ ex-‘
5 ploslon may occur if, at the timeof lighting, an
that the ignitingmeans will be effective for each
and. every burner at which the fuel supply is
available to obviate the possibility that‘ the ignit
explosive mixture of fuel and air is in the furnace.
To avoid this it is the practice in kindling a ?re ing means might function in front of a burner
in a furnace to ?rst thoroughly purge or‘scavenge at which fuel is not available, while another
the furnace by effecting a flow of air through burner some distance away was feeding fuel to
10 it. This may be done by natural draft or by
the furnace but the igniting means for» that‘
starting up one of the draft fans, usually the in burner was‘ not effective, thus resulting in a
duced draft fan, and operating it for a length loading of the furnace with a mixture which
eventually might become ignited with disastrous
of time sufhciently to thoroughly purge or scav
enge the furnace, after which the fan may or may
not be stopped as found desirable and the fire
20, 1933, I have disclosed and claimed a method '
and apparatus of control mechanism for a fur-‘
20 nace whereby it is not possible for an operator
to supply fuel to a furnace and kindle a ?re
therein without having ?rst scavenged the fur
nace and whereby if having scavenged'the fur
nace .he delays kindling the ?re until‘ the air
25 flow through the furnace decreases below a cer
tain value, then he mustagain scavenge the
furnace in order that he may supply fuel there
to’. By this arrangement there is avoided the
possibility that the operator may scavenge the
30 furnace, delay kindling the ?re until the scav
enging may have become ineffective, and then
kindle the ?re without properly again scaveng
ing the furnace.
35 in connection with a- furnace a‘fuel supplying
means, a fuel igniting means, and a control means
able through a burner its fuel igniting means
is made operative.
A-still further object is that the main fuel
supply to all of the burners of a boiler closes upon
the failure of air flow through the furnace below
a predetermined value, or upon failure of ?ame
within the furnace. '
Still another object is‘ an interlock arrange
mentresponsive not only to the rate of air ?ow
through the furnace but also to the rate of supply
of fuel to the furnace.
Still further objects will become apparent
from a study of the drawings and speci?cations‘
relating thereto.
For a consideration of what I believe to be
novel and my invention, attention is directed to
vIn the drawings:
Fig. 1 is a diagrammatic view of a furnace _
whereby‘ the fuel supplying means and the fuel
provided with control mechanism embodying my
igniting ‘ means cannot be rendered operative
until a predetermined ?ow of air obtains in the
Fig. 2 is a diagrammatic view of a plurality
of burners and control therefor, similar to'the 40
furnace,’ the arrangement preferably being such
that, the fuel supplying means cannot be oper
ated until after the fuel igniting means has been
Modern furnaces, and particularly boiler' fur
naces, maybe equipped with a large number of
burner and control arrangement of Fig. 1.‘ ‘
Fig. 3 illustrates diagrammatically a further
embodiment of the invention applied to a plu
rality of burners.
Fig. 4; diagrammatically illustrates a still furf 45
separate burners for pulverized fuel, oil or gas,
ther embodiment of the invention in connection
and in some cases, there maybe as high as
with ‘a plurality of burners.
Referring ?rst to Fig. l, 1 indicate‘ therein a. '
furnace ‘l which may be of any suitable type,
twenty or thirty such burners for an individual
furnace. The kindling or lighting off of such a
furnace presents a problem to the solution of
which the method and means of the present in
but shown in the present instance as being a fur
cated at t.
One object of my invention‘is to provide an
improved construction, and arrangement of con-‘
in C?
‘the following speci?cations and claims appended
My prior patent is further directed to provide
, A further object is to provide an interlocking
arrangement such that if and when fuel is avail
In my prior Patent No. 1,914,949, granted June
trol mechanism for a furnace whereby the fuel
nace for heating a boiler having boiler tubes indi
At 3 is indicated a fuel supply for the furnace
and in the‘ present instance‘ represents a gas
supply line from which a maincontrol valve t
igniting means cannot be ‘made operative until a for the boiler 'l controls the supply of gaseous
predetermined ‘flow of scavenging ' air ,_;e_xists ‘xfl'lel to a‘ header'?common to all'of the burners
through the furnace and whereby thefuelwqfe‘ed-ly I,‘ supplying the boiler l. The fuel supply, orvgas
ing means preferably cannot be operated until
the fuel igniting means have been‘ started,“ ,
line‘ 3, islt‘o be taken asltypical .of any suitable
‘means for supplyingfu‘el to a furnace‘ and may co
‘ 2,127,445
represent, for example, a means for supplying
oil, gas, pulverized fuel or the like. In the pres
ent instance the control valve 4 is spring loaded
by a spring '3 to normally closed or shut off posi
tion and adapted to be opened for ?ow there
'through by the energization of a solenoid ‘I.
In Fig. 1 I illustrate a single burner and its
control leading from the header 5 to the furnace
I, while in Fig. 2 I show‘a plurality of such burn
ers and the interlocking control circuit therefor.
The single burner and related apparatus of Fig. 1
may be considered as the only burner feeding the
boiler_ I, or may be considered as one of the plu
rality'of burners illustrated in Fig. 2. Likewise
the three burners constituting the plurality of
burners of Fig. 2 may all be feeding the‘ furnace I
or may be a part only of a larger number of burn
_ ers all related to the furnace I.
Referring particularly to Fig. l, a pipe 3 leads
20 from the header 5 to a burner 9.
Interposed in
the pipe-3 are two control valves I 2, II whose
functioning and purpose will be described herein
connections are shown as being made across the
second and third passes of the boiler furnace. It
will be understood however that this is only by
way of example and that the connections may be
. made to any two suitable points, the essential
thing being that the bells be subjected to a di?'er
ential pressure of sufficient value to eifect the
operation of the ?ow responsive device 22.
The movable element of contact 24 is connected
by conductors I30, Hi to one side of electrical 10
supply lines 32. Interposed between the conduc
tors l3lI, I3l is a ?ame failure detector 33 which
may comprise electrodes of a carbonaceous mate
rial such, for example, as silicon carbide posi
tioned in the path of the ?ame within thev fur 15
nace. While I have shown but a- single ?ame
failure detector positioned adjacent one of the
burners of Fig. l and Fig. 2, it is my concept that
there might be a single ?ame failure detector for
an entire furnace, or one for each burner of a 20
furnace (Fig. 3), or intermediate number.
Shunted across the ?ame failure detector 33 is
a switch blade 34 shown in open position. The
stationary element of contacts 24 is connected by
a conductor 35 to the other side of the supply 25
Theburner 3 extends through a wind-box? l2
supplied with forced draft by a motor driven
blower I3. I4 indicates a torch, such as an oil ' lines 32, such conductor including the winding of
or gas torch, for use in kindling or lighting the
furnace. The ?ow of fuel through it is controlled
by a valve I5 adapted to be opened by a solenoid
30 I3 and closed by a spring I I6. At I1 is an igniting
means for the torch, such as a spark plug. It is
connected to the secondary winding of a trans
former I3.
I3 indicates the stack of the furnace and 20
35 indicates an induced draft fan driven by an elec
tric motor 2I.
The furnace construction so far
described is illustrated only diagrammatically and
by way of example and is to be taken as repre
sentative of any suitable. furnace provided with a
40 fuel feeding means and a means for effecting ?ow
of air through the furnace.
According to the embodiment of my invention
illustrated in the drawings I provide a mechanism
' 22 which is responsive to the rate of flow of air
45 through the furnacevand I provide such device
with a contact closing arm 23 which when the
flow of air through the furnace reaches or ex
ceeds a predetermined value effects the closing of
a pair of contacts 24. Contacts 24 are biased
60 ' toward open position so that they are. open except
a solenoid 36. Solenoid 38 has a pair of contacts
31 which are bridged, or close-circuited, when
ever solenoid 36 is energized.
The primary winding of transformer I8 and the 30
winding of solenoid it are connected in series to
one of the supply lines 32 by conductor 38, in
cluding the contacts 31 of the solenoid 36. The
other side of the transformer primary winding is
connected to the other supply line 32 by a con 85
ductor 39, hand switch blade 42, and conductor
I3I; conductor 38 including contacts 40 which are
open-circuited at all times the valve II is closed. -
When valve II is opened through the agency of
hand wheel SI, then contact bar 4I immediately 40
engages and closes the circuit of contacts 40.
throughout all positions of opening of the valve I I.
The switch blades 34 and 42 are Joined for si
multaneous ‘operation and with them a third
switch blade 43 which Joins conductor 38 with a
conductor 44, the latter leading to the winding of
solenoid ‘I. A conductor 41 joins the other termi
nal of solenoid ‘I with a hand operable switch 48
connected by conductor 43 to the electrical sup
ply lines 32. Solenoid ‘I when energized is adapt
ed to close the circuit across the contacts 45, thus
by-passing the switch blade 43 to lock valve 4 in
when held closed by the flow responsive mecha
In the present instance the flow responsive de ' an open position.
vice is shown as comprising a casing 25 in which is
The circuit of solenoid 'I on the main fuel valve
55 a sealing liquid, such as oil, for sealing two in
.4 may be traced as follows; power line 32, con
verted bells 26, 21 connected to opposite ends of a ductor 46, switch 43, winding of solenoid 1, con
lever arm 23 pivoted centrally to a ?xed point. .ductor 44, switch blade 43, conductor 38, and con
Contact arm 23, is connected to lever arm 23 and tacts 31 to the other side of power line 32. As
forms a part of it. The arm 23 extends at an previously mentioned the switch blade 43 may be
angle to the lever arm 23 and is weighted by by-passed by a holding-in circuit including the 60
means of a suitable weight 29, which biases the contacts 43.
bell structure to a position as shown in the draw
In the pipe 3 in the direction of gas flow to
ings, which position it occupies at no air ?ow
through the boiler furnace. When arm 23 is the burner 3 is located a hand operable valve III
of a bleeder type‘having a small bleeder port 50
65 moved into engagement with contacts 24 it moves
toward vertical position but does not move beyond leading to the atmosphere and arranged so that
the vertical, that is beyond dead center. It- tends
always therefore to move toward the position 50 is opened to the atmosphere to bleed from be
shown in‘ the drawings wherein contacts 24 are tween the valves IO and II any gas leakage past
70 open. .Bells 26, 21 are connected by pipes 33 and the valve ll toward the furnace. The valve II 70
3 I _to points of differential pressure in the furnace located in the pipe 3 between the valve III and the
whereby the bells are subjected to a differential burner 3 is of a hand operable type adapted in its
- pressure which bears a definite relation to the
closed position to open-circuit the contacts 40 and
' rate of flow of air and/or products of combustion
through the furnace. In the present instance the
thus effectively de-energize solenoid I8 and trans
former primary ll. When solenoid It is so de 75
' energizedthe spring H6 immediately closes the
torch valve I5.
Referring now in particular to Fig. 2, I show
such a flow "of air of a definite predetermined
magnitude is established the furnace cannot be
As the flow of air through the furnace increases
therein three burners, 9, 9A‘and 9B, which are
_representative of a plurality of burners similar a differential pressure is appliedto the flow re
to the burner 9 of Fig. 1, and each provided with sponsive device 22. which differential increases
a torch and igniting means as in Fig. 1. The a with the rate of ?ow in known manner. As soon
' various equipmentand arrangement of Fig. 2 is as a predetermined rate of flow is reached the
similar to that of Fig. 1 except that in Fig. 2 differential pressure applied to bells 28, 21 will
I illustrate diagrammatically my proposed ar
be sufficient to turn lever arm 28 on its pivot in 10
rangement of interlocking for operation of the r a clockwise direction and move contact arm 23 to
a position wherein it closes the contacts 24. The
various burners of a plurality of burners on a
single furnace. The valves l8. IOA, I03 may be arrangement is such that a predetermined flow
similar. to the ‘valve in of Fig. 1 and may be of air and/or gases through the furnace is re
provided with leakage'ports 50.
quired before the contacts 24 are close-circuited. 15
> The closing of contacts 24 completes one step
,The circuit for controlling and igniting each
torch includes the primary of the transformer l8, in the sequence necessary to energize the sole
the solenoid _l 6, and the contacts 48, in series with noid 38. When the switch blade 34 is closed
(by-passing the ?ame failure detector 33) sole
each other across the conductors 38, 49. For a
noid 36 is energized closing contacts 31 for the 20
20 plurality of burners, as in Fig. 2, the igniting cir
energization of conductor 38.
cuit for each of the burners-is connected in par
Simultaneously with switch 34 the switch ?n- _
allel across conductors 38, 49. The arrangement
.is such that the torch valve I5 is closed (by spring gers 42, 43-are closed; switch 42 energizing con
H6) and transformer I8 ineifective when the fuel ductor 48, and switch "accomplishing one step
in completing the circuit to the fuel supply valve 25
25 supply valve H is in a tight closed position where
by contact bar 4| does not short the contacts 48. . solenoid ‘I, which is further controlled by switch
Immediately the valve ll begins to open and for 48.
The switch 34, 42, 43 may be closed by the
all positions of opening, the contact bar 4i shorts
the contacts 48, energizing solenoid IE to open operator either before or after purging the boiler. '
Assume for the moment that the boiler has been 30
30 the torch supply valve l5 and at the same time
purged, contacts 24 closed and that switch 34,
energizing the transformer l8 to actuate the ig
niting spark l1. This, assuming for the moment
that conductors 38, 49 are alive.
Conversely when the valve II is closed, thus
35 stopping the flow of fuel through the burner 8.
immediately the torch l4 and igniter II are made
the possibility of an igniting ?ame opposite a
40 burner through which no fuel is being admitted
to the furnace. As will be seen hereinafter, the
arrangement is such for each of the burners as
to prevent the possibility of having fuel admis
sion through a given burner without having the
45 igniting means and torch operative for igniting
making energy available on conductors 38, 49 and
also effecting energization of the circuit of sole
noid 1 except for the switch 48.
This prevents . closed at this point, fuel will be available at
ineffective, regardless of the condition of the re
mainder of the electrical circuit.
42, 43 is‘likewise closed. The resulting energize.
tion of solenoid 36 will cause contacts‘3‘i to close,
The arrangement just brie?y described pri
marily effects a safeguard against fuel being ad
mitted through the .burner 8, for example, to the
50, furnace with the igniter l1 and torch l4 inopera
tive and at the same time no-fuel being admitted
through the burner 93 while the igniter “B and
torch MB were operative. This hazardous condi
tion which is prevented by my arrangement would
Switch 48 may be closed now or later.
valves Ill. IOA, IOB, or if these valves are open
then at valves II, “A, “B. If for example, 40
valve II is open then its opening will have com
pleted the circuit between conductors 38, 48 for
energizationof torch valve 5 and ignition trans
former l8 so that torch I4 is available for light
ing burner 8 when fuel arrives.
Valve ll may be opened either before or after
main supply valve 4. If opened prior to the
opening of valve 4 then immediately as it un
seats, the torch i4 is lighted and is thereafter
available when solenoid ‘I is energized and gas 50
flows through the burner 8.
i ;
As long as switch 34, d2, 43 is closed each
igniter becomes active as soon as its valve II is
opened and stays active until switch 34', 42,43
burner to the furnace at a distance of possibly 15
is opened, which can only be done after detector 55
33 is heated up and passes current through the
to ‘20 feet fromv the point where the torch was
lighted, and thus the filling to a. large extent of
60 the furnacewith a combustible'mixture before
solenoid ‘l is energized and immediately com
pletes a holding circuit around contact d3 by 60
in C, allow on a large modern furnace for the feeding
of a . considerable volume of fuel through one
' ‘With the closing of contacts 31, d3, t8 the
' the contacts 4%.
the same became ignited.
As soon as flame exists across the detector 33
The operation is as follows:
Assume that the furnace is shut down and that to the extent of completing circuit, switch“, “2,
d3 may be opened, thus'de-energizing the trans
it is desired to kindle same. The air-flow respon
formers l8 and ‘allowing springs iii to close off
' sive device it will occupy the position illustrated
‘ in Fig. 1, namely, contacts 24 being open. The, the various torches l4. Thereafter while the
operator ?rst effects a flow of air through the furnace is in normal operation the system as a
furnace to scavenge it. This may be done by whole is under the protection of contacts 24, de
natural draft or by means of the induced draft tector 33, or hand switch $18. If it is desired to
fan, the forced draft blower, or both, the means cut off the fuel from the boiler as a whole, then
by which the flow of air is established, depending a hand switch it may be pulled. it air flow de
upon the nature of the particular furnace in
stallation to which the invention is applied. The
essential thing is that a flow of air be established
through the furnace to scavenge it and that until
creases to a predetermined minimum then con
tacts 2“ will automatically open tie-energizing
solenoid 36, opening contacts ill, and thus de-_
energizing‘ solenoid ‘l to shut off the fuel supply. 75
Similarly should ?ame fail at the detector 33 it
de-energizes solenoid 36 resulting in a closure of
main fuel valve 4.
It will be observed that the main fuel supply
:1 to the furnace, as well as the ignition and
kindling means for each and every burner, are
all under the direct control of the air flow re
sponsive contact 24 and/or the ?ame detector
33. It will .be understood that the circuit may be
arranged to have a detector 33 opposite each of
the burners or one detector common to all of the
burners. Fig. 3, for example, illustrates an em
bodiment wherein there is a detector 33 opposite
control valve 4 for that particular furnace.
They therefore are independent of the opening of
valve 4. Between the torch supply takeoff and
valve 4 I indicate at 13 an ori?ce, or other re
striction in the pipe line 3, for creating a pres
sure di?erential bearing a known relation’ to the
rate of flow of fuel through the pipe 3 toward
the burners 9. Connected to be responsive to
such differential pressure is a diaphragm meter
12 adapted to close a switch 14 when a prede 10
termined rate of fuel flow exists.
The hand switch 15 is used to start the furnace
and “indicates the contacts of the air ?ow re
sponsive device 22 previously mentioned. 64 and
In brief, after the furnace is in operation the 65 indicate solenoids, the former controlling con 15
solenoid 36 controls the supply of fuel to the tacts 66, 6'! and the latter controlling contacts
furnace and to all burners thereof and the sole
68, 69. The various torch controlling solenoids
hold 36 will fail if the ?ame fails at the flame
l6 and ignition transformers iii are for each
failure detector 33, ‘or if air ?ow through the burner connected in parallel across conductors
20 furnace decreases below a predetermined‘. value,
W, ‘H.
thus opening contacts as.
[it ‘i I have indicatedv a coil, such as the sole
In Fig. 3 I illustrate a further embodiment noid ‘I of the remainder of the drawings and
each burner.
wherein a flame detector is located adjacent each
of the burners of a plurality of burners. Fur
which may be a torque motor or a thruster.
The requirement being that the valve 4 remain
25 thermore the switches 34, 42, 43 have been omit;
open only when the coil 1 is energized.
ted and each igniter is ready at all times to act.
All that is required is that the detector 33 be
cool and that contacts '40 be closed.
The circuit for the solenoid ‘i is under control
30 of the hand switch 43 and the flow responsive
switch 24. The ignition and torch means of
In kindling the furnace of Fig. 4-1 assume
?rst that switches 14,15, and 24‘ are open as
indicated. The furnace is purged or scavenged
by effecting a flow of air and/or gases su?lcient
to actuate the device 22 and close the contacts 30'
24. Such closure energizes solenoid 64 which
closes contacts 66, 61. If it is now desired to
each burner are under the control of flow re
sponsive switch 24, detector 33,‘and contacts 453.
In kindling the furnace switch 24 automatical
35 ly closes when the air flow reaches a predeter
mined value. The detector 33 being cool, the
solenoid 62 is in the shown position with contact
63 closed and as soon as valve ll begins to be
opened (closing contacts 40) ?ow-is established
40 through torch l4 and igniter i1 is actuated.
This regardless of whether or not hand switch
43 has previously been closed, thus opening
valve 4.
Any or all of the burners 3, 3A, etc. may be
45 lighted off in this manner, for the ignition and
. 25
kindle the furnace, starting switch 15 is closed by
hand,- which in conjunction with contacts GB
eil'ects energization of solenoid 65, thereby clos 35
ing contacts 68, 69. Fuel supply valve 1 opens
due to energization from a circuit completed
through contacts 61 and 68 but no gaseous fuel
?ows toward the burners unless the various hand
valves at the outlet of valve 4 and the valves iii
in individual burner lines are opened.
Simultaneously with the energization of the
coil 1, occurs actuation of each and every torch
valve l6 and igniting transformer l8 through
torch means are always available, and as soon as
a circuit controlled by contact 69. v The torches 45
any valve II is opened thus closing contacts 40,
being supplied through each or all of the burner
are all lighted irrespective of whether gas is
the torch will be lighted, if a predetermined ?ow , pipes 9, 9A, 3B. Whichever one of the burner
of air exists whereby contacts 24 are closed.
pipes has gas ?owing through it will then be
During operation if-at any time air flow falls kindled. ‘As soon as a predetermined ?ow of gas
to a predetermined minimum, the switch 24 will - occurs through the valve 4, effective upon the 50
open, thus closing the fuel supply valve 4 for the
furnace. Failure of ?ame at a detector 33 de
energizes solenoid 62, closing contacts 63 whereby
the ignition means immediately comes into play
and assuming that valve ll remains open, it
lights it off immediately. If, however, valve H
has been closed then the ignition means remains
in condition to immediately function upon open
ing of valve ii.
The common ?ame detector of Fig. 2 could
still be retained to close valve 4 if desired.
In Fig. 4 I show a further embodiment of my
invention applied to a plurality of burners, each
equipped with torch and igniting means, but for
the sake of simplicity I have not included in this
part of the drawings the ?ame detectors 33, al
though it will be understood'that they may be
applied to this arrangement as well as to the
70 ones previously described. Herein I introduce
a further safety feature, namely, in connection
with the rate of supply of fuel to the plurality of
The torches l4, I4A, I43 ~ are supplied with
75 gaseous fuel from the conduit. 3 ahead of the
meter 12, the switch" is closed, thus by-pass
ing contact 68 and locking in the coil '5 whereby ‘
valve 4 stays open even after the ignition means
are extinguished by opening the starting switch 55
After the furnace is in operation if at any time
the gas ?ow through the ori?ce 13 decreases
to a predetermined minimum then the switch
14 is opened, de-energizing coil 1 and closing valve 60
4. Before valve 4 can again be opened and gas
admitted to the furnace the starting switch ‘276
must be closed by hand to actuate solenoid 65.
During operation the entire fuel supply and
igniting system is under the control of the air 65
flow actuated switch 24, so that if air ?ow through
the furnace decreases to a predetermined mini
mum, switch 24 opens deenergizing solenoid 36,
opening contact 61, and closing fuel supply
valve 4.
In connection with all four of the ?gures of
the drawings it will be seen that by my invention
in starting the furnace the operator must ?rst
effect a ?ow of air through the furnace so as to
thoroughly scavenge or purge it prior to kindling 75
the ?re and that a ?ow of air sufficient to main
tain the flow responsive device in the position
wherein it closes contacts 24 must be maintained.
or the fuel feeding means and the igniting meansl
cannot be put into operation. In this connec-.
tion the flow responsive‘ device may be so ar
ing means will be operated in the absence of
flame from the corresponding burner and ren
dered inoperative in the presence of ?ame from
the corresponding burner;
ranged that having been moved by a prede
termined ?ow of air through the furnace to
effect closing of contacts 24 it will, due to weight
29 having moved to a more nearly vertical posi—
tion, stay in such position until the flow de
. _ creases by a certain amount.
By this means the
draft through the furnace may be decreased
somewhat over that required to close the con
15 tacts 24, and still the contacts will remain closed,
which means that if desired the arrangement
2. In combination with a . furnace having a
plurality of burners, a conduit for supplying fuel
to all of said burners, a main valve in said con
duit, means responsive to the flow of air through
said furnace, means controlled by said first named
means for opening said main valve when a prede 10
termined or greater rate of air fiow exists
through said furnace and closing said valve when >
the rate of air flow falls below said predetermined‘
rate, an individual burner valve for admitting
fuel to each of said burners,‘fuel igniting means 15
associated with each of said burners, means per
mitting operation of each of said igniting means
to scavenge the furnace, after which the draft. when the corresponding burner“ valve is open
may be shut down somewhat during the kindling and preventing operation of the igniting means
when the corresponding burner valve is closed, 20
'20 operation.
It will be. understood that it is not absolutely means under the joint control of said ?rst named
necessary for the air supply responsive mech- means and each ?ame responsive device to insure
that the corresponding igniting means will be
anism to be interlocked with both the fuel sup
may be such that a stronger draft must be used
plying means and the fuel igniting means as I
25 may utilize an arrangement wherein the air sup
ply responsive means is interlocked only with the
fuel supply means or only with the fuel igniting
It is to be understood that while I have illus
.30 trated my invention in connection with a fur
nace burning gas, this is only by way of ex
ample, and that the invention may be utilized in
connection with furnaces burning other fuels,
such as oil or pulverized coal for example. Fur
it is not necessary to have the
35 thermore
furnace arranged for heating a vapor generating
boiler, but'the furnace may be of any type or for
operated in the absence of ?ame from the corre
sponding burner and rendered inoperative in
the presence of ?ame from said burner.
3. In combination with a furnace having a
plurality of burners, a conduit for supplying fuel
to all of said burners, a main valve in said
conduit, means responsive to the flow of air 30
through said furnace, means controlled by said
?rst named means for opening said main valve
when a predetermined or greater rate of air
flow exists through said furnace'and closing said
valve when the rate of air flow falls below said 35
predetermined rate, an individual burner valve
for admitting fuel to each of said ‘burners, fuel
igniting means asociated with each of said burn
ers, and means under the joint control of said
rated in the system. For example it is not essen- - ?rst named means and- each ?ame responsive de
vice to render said igniting means operative in
tial that all of the interlocking be done elec
the absence of ?ame from the corresponding
trically. It may be readily accomplished hy
burner and when said predetermined or greater
draulically or by pneumatic means and instru
mentalities differing from those which I have air flow exists through the furnace; and to render
illustrated and described may readily be adapted said igniting means inop'erative in the presence 45
of ?ame from the corresponding burner or when
to the invention.
In accordance with the provisions of the patent the air flow through the furnace falls below said
predetermined rate.
statutes I have described the principle of opera
4. In combination with a furnace having a
‘ tion of my invention together with the apparatus
plurality of burners, a conduit for supplying fuel 50
which I now consider to represent the best em
to all of said burners, a main valve in said con
bodiments thereof, but I desire to have it under
duit, means responsive to the flow of .air through
stood that the apparatus shown is only illustra
furnace, means controlled by said first named
tive and that the invention may be carried out by
means for opening said main valve when a pre
other means.
determined or greater rate of air flow exists 55
.What I claim as new, and desire to secure by through
said furnace and closing said valve when
Letters Patent of the UnitedStates, is:
the rate of air flow falls below said predetermined
1. In combination with a furnace having _a plu
rality of burners, a conduit for supplying fuel to rate, an individual burner valve for admitting fuel
to each of said burners, fuel igniting means asso
all of said burners, a main valve in said conduit, ciated with each of said burners, and means 60
, under the joint control of said ?rst named means
any service. '
Various forms of apparatus may be incorpo
furnace, means controlled by said ?rst named
' means for opening said main valve when a pre
determined or greater rate. of air ?ow exists
throughv said furnace vand closing said valve
when the rate ofv air flow falls below said pre
determined rate, an individual burner valve for
admitting fuel to each of said burners, fuel
igniting means associatedv with each of said
burners, and means under the joint control of
said ?rst named means and each flame respon
70 sive
device to insure that the corresponding ignit
and each of said burner valves for permitting
operating of the corresponding igniting means
when said predetermined or greater air ?ow
exists through said furnace and the corresponding
burner valve is open; and preventing operating
of the corresponding igniting means when the
rate of air flow falls below said predetermined
rate or when the corresponding burner valve is
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