US2297821A - Combustion control and safety alarm system - Google Patents

Description

Oct. 6, 1942. H WHEMPNER 2,297,821

COMBUSTION CONTROL AND SAFETY ALARM SYSTEM Filed May 26, 1959 i I l 09 l 68- 1 l IGREE?) I I29 l 135 l l 138 80 l we I Russell H. Whempner .of the relays occurs in response to Patented Oct. 6, 1942 ICE COMBUSTION CONTROL AND SAFETY ALARM SYSTEM Russell H. Whempner, Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application May 26; 1939, Serial No. 275,920

11 Claims. (01. 158-28) The present invention relates to combustion control apparatus embodying particular signal and alarm arrangements in combination therewith.

The invention is intended principally but not exclusively for industrial combustion systems, especially gas fired furnaces and boilers. 'The larger of these installations are usually manually controlled, that is, they are put in operation and cut out of operation manually. Other installations may be completely automatic. My invention comprehends. a combination and arrangement of safety controls, alarms, and signals whereby the optimum in safety of operation is secured.

My invention features particularly an alarm arrangement so devised that an alarm is given only upon the occurrence of an unsafe condition of the system. In the past similar alarms often gave an alarm whenever the system was started or stopped, greatly disturbing personnel and causing confusion and a general exodus from the vicinity of the furnace or boiler where the alarm originated.

An object of my invention is to provide improved safety control combinations and arrangements for combustion systems wherein the system is fully automatic in operation or is manually started and stopped.

Another object is the provision of an improved automatic interlocking control arrangement for combustion systems, embodying signal devices arranged to apprise the operator of the safe or unsafe progress of the sequence of operations and the condition of the system and to give an alarm only in the event of the occurrence of an unsafe condition of the system.

Another object is to provide an alarm device and arrangement for combustion control systems wherein the alarm cannot be sounded in responseto normal functions of the system but only upon the occurrence of an unsafe condition thereof.

Another object is to provide an alarm system comprising an alarm device, and interlocking relays so arranged that one relay is actuated in response to the other and the alarm only sounds when a predetermined interlocking relationship specific unsafe'or abnormal conditions. I

The figure of the drawing represents a gas fired combustion sys membodying the control and alarm arrangem nt of my invention therein.

Referring to the drawing, at [III have shown a gas fired boiler which may be 01' a conventional 5 type and which forms a part of an industrial boiler and system, my invention of course may be applied to various other types and forms of systems using difier'ent kinds of equipment.

The gaseous fuel fed to the burner I i through a conduit I2 which may be connected to a gas supply main (not shown). interposed in the conduit I2 is an electrically operated gas control valve l3 which may be of a known type.' The electric valve l3 incorporates an auxiliary switch H which is operated by the valve mechanism, and is closed whenever the valve I3 is in closed position. Ahead of the valve [3 in the conduit I2 is another valve l5 which is a manually operable valve having an operating handle It. When the handle I6 is in the position shown, the valve I5 is closed, and whenthe handle it is moved to a vertical position the valve is opened. The valve i5 also incorporates an auxiliary switch I! which is closed when the valve 15 is in closed position.

Adjacent the burner H is a small pilot burner l8 which is supplied with fuel through a tube 18 connected to the conduit 12 ahead of the valve I5. Interposed in the tube I9 is a small electric valve 20 which controls the supply of fuel to the pilot burner l8. Arranged within the combustion chamber so as to be impinged upon by the pilot burner is a control electrode 23 which cooperates in the control of my system in a manner which I will presently describe. Also arranged adjacent the outlet of the pilot burner I8 are a pair of electrodes 24 which are arranged to" form a spark gap, the purpose of which is to ignite the pilot burner when it is desired to start the system in operation.

The electrodes 24 are connected to the sec- 26 which is arranged to be opened when the water lever in the boiler falls below a predetermined level. The; low water cut-ofi 25 is connected to the boiler drum by pipes 21 in the usual manner and also communicating with the pressure within the boiler is a pressure responsive switch 28 incorporating a mercury switch 28 which is normally closed, but is opened when the pressure within the boiler exceis a predetermined value. Numeral 30 designates a blow down valve for purposes of periodically blowing down and clearing the low water cut-off of scale and the like.

The control system which I employ embodies a flame detecting relay mechanism which I have designated generally at 22. The flame electrode 23 forms a part of the flame detecting mechanism 22. The flame detecting relay mechanism is of the electronic type and embodies an electronic valve 3| which takes th form of an electronic tube of the twin type amplifier which, for example, may be an RCA type 6C8 tube. The tubeis triode B. The triode A includes an anode 32, I

a cathode 33, heater filament '29 and a control electrode or grid 38 which, as shown, is connected directly to the cathode 33. -The triode B includes an anode 35, the cathode 36, heater filament 38 and a control electrode 31. The mechanism 22 includes a combination step-up and step-down transformer 38 having a primary winding 39 and secondary windings 40 and ill. The secondary winding 50 is a low voltage secondary and is connected to the heater filaments 29 and 38 by wires 82 and 63. The secondary winding ill is a relatively higher voltage winding and is connected to the anode 32 by a Wire 83, the' other terminal of winding ll being connected to a resistance 85 which forms in effect a voltage divider resistance. The cathode 33 is connected to the resistance 45 by wire 36. The triode A, as pointed out above, acts as a rectifier to supply a direct current voltage for operation of the triode B and whenever the transformer 38 is energized by reason of the triode A, a direct current voltage appears acrossthe resistance 45. A condenser All" is connected across the resistance 85 for the purpose of filtering out the alternating current component of the current which flows in the circuit of triode A. The positive end of resistance 45 which is connected to cathode 33 is also connected to ground as shown, through a resistance 98.

The cathode 36 is connected to an intermediate point on resistance 45 which may be the mid point as shown by wire 49. The grid 31 is connected to the negative end of th resistance 45 by a wire 50, there being a resistance 5| interposed in series with the Wire 50. The tendency of the connection formed by the wire 50 is to bias the grid 31 negatively with respect to cathode 36.

Thegrid 31 is also connected to the flame electrode 23 by a wire 52. The tube leading to the pilot burner I3 is grounded as shown at 53. In this type of flame detecting equipment, th pilot burner flame is adapted to create a path of lower resistance to flow of electricity between th electrode and the ground 53 than exists when the anism 22 is a relay unit 55 including a winding 56 cooperating with an armature arranged to actuate switch blades 51 and 58 which'are moved to the left into engagement with fixed contacts 59 and 68, respectively, when the winding 56 is energized. The blade 51 engages with a contact 6i when the winding 56 is deenergized. One end of the winding 56 is connected to the positive end of the resistance 45 bya wire 62 and the other'end of the winding 55 is connected to the anode 35 of triode B by a wire 63. Whenever transformer. 38 is energized an there is no flame at the pilot burner l8 the grid 31 is biased sufficiently negatively so that not enough current flows in the circuit of th winding 58 to cause the blades 51 and 58 to be moved to the left. When flame appears at the pilot burner I8 as described above, a path of lower resistance is completed from the grid 31 to ground and it becomes biased less negatively so that a current flows in the plate circuit of triode B causing the relay 55 to be energized. This circuit is as follows: from resistance 45 through wire 62, winding 56, wire 83, plate 35, grid 31, cathode 36, and wire 49 back to resistance 85, the potential across resistance between its positive end and the point where wire 49 is tapped ofi supplying the power for operating relay 55.

Numeral 55 designates a signal and alarm relay mechanism which constitutes an important part of my invention, particularly in the manner in which it cooperates with the other portions of the system. The signal and alarm relay mechanism 55' includes a relay unit 66 and a relay .unit '61. cooperating with an armature arranged to actuate switch blades 69 and 18 which are moved to meral 8| indicates a red signal light which is on when an unsafe operating condition of th system occurs. Numeral 82 indicates an alarm bell which rings automatically in response to the.

failure or disappearance of .flame in the combustion chamber, which of course is indicative of a hazardous condition by reason of the possibility of accumulation of unburned gaseous fuel in the combustion chamber. I

Numeral 85 designates a manual control station embodying a stop button 86 cooperating with electrical terminals 81 and 88 and a start button 89 cooperating with electrical terminals 90 and 9|.

To start the system in operation the operator pushes the start button 89 and holds it against the terminals 90 and 9| until the green light 80 comes on, this signal light being located on a panel board suitably situated so that the operator'can see it from the position he is in when operating the switches at the manual control station 85. When the start button engages the terminals 90 and-9|, a circuit is completed for energizing the transformer 38 provided that both the valves l3 and [5 are in closed position so that the auxiliary switches 14 and I1 are closed. The switches 26 and 29 must of course also be closed. The circuit for energizing the trans- The relay unit 66 has a winding 68 I scribed above from course not be energized in stop button 91, wire 99,

H3, contact 69,

. I99, wire I9I, winding former 99 is as follows: from wire 92 through the stop button 96, wire 93 through the start button 99, ,wire 94, switch I4, wire 95, switch I1, wire 96, wire 91, switch 26, wire, 99, switch 29, wire 99, wire I99, wire I9I, winding 99 of the transformer, wire I92 back to the wire 99. The wires 92 and 93 may be connected to a suitable source of external power (not shown). At the same time that transformer 99 is energized a circuit is completed for transformer 2| as follows: from wire 92 through stop button 96, wire 99, start button 99, wire 94, switch I4,- wire 95, switch I1, wire 99, wire91, switch 26, wire 99, switch 29, wire 99, wire I99, wire I99, switch blade 51, contact 9!, wire I94, winding 94 of transformer 2|, wire I95 and wire I96-back to wire 99. At the same time as the circuits just described are completed, a circuit is also completed for energizing and opening the valve 29 for admitting gas to the pilot burner I9. This circuit is as follows: from wire 92 through stop button 96, wire 93, start button 99, wire 94,. switch I4, wire 95, switch I1, wire 96, wire 91,

switch 29, wire 99, switch 29, wire 99, wire I91, valve 29, wire I99, wire I99, wire H9 and wire I96 back to wire 99. Energization of the ignition transformer 2I causes a spark to be produced between the electrodes 24 which ignites the gas from the pilot burner I9, gas beginning to flow of course as soon as the valve 29 is open.

As soon as the flame appears at the pilot burner I9, a low resistance path will be produced as'dethe grid 91 to ground and due to the less negative bias now on the grid 91, current will be permitted to flow in theplate circuit of triode B thus energizing the relay 55, the circuit being'as described above. If the pilotburner failed to ignite, the relay 55 will of the manner described. As soon as the relay 55 is energized, closure. of switch 59 completes a circuit for energizing the transformer 39 which'is independent of the start button 99 and the switches I4 and I1. This circuit is as follows:' from wire 92 through the wire III, wire II2, wirea switch blade 59, wire II4, wire wire 99, switch 29, wire 99, wire 99 and wire I92 back to wire 93. This circuit is made independent of 91, switch 26,

"the switches I4 and I1 so that the valves I3 and I can now be opened without causing deener- Eizatlon of transformer 99. When the circuit last described is completed, a circuit for energizing valve 29 is also completed which circuit is likewise independent of the start button 99 and the switches I4 and 11. This circuit is as follows: from wire 92 through stop button 96, wire 99, wire III, wire II2, wire 9,. contact 69, blade 59, wire II4, wire 91, switch 26, wire 99, switch 29, wire 99, wire I91, valve 29, wire I99, wire I99,'wire H9, and wire I96 back to wire 99. Itwill be seen that the circuits for transformer 99 and valve 29 which extend throughthe-switch 59 are common as far as wire 99. Now at the same time that relay 55 is energized and causes completion of the above describedenergizing the ignition circuits which are independent of the start but ton, a circuit isalso completed for energizing and opening the valve I9 as follows: from wire "through stop button 99, wire 99, wire II I, wire II2, wire II9, contact 69, blade 59, wire I I 4, wire 91, switch 26, wire 99, switch 29, wire 99, wire I99, wire I93, blade 51, contact 59, wire H5, wire II6, valve l9, wireII1, wire 9 and wire I96 back to wire 93. When valve I3 is automatically 92 through stop button 96, wire III, wire H2,

wire II9, contact 69, blade switch 26, wire 99, switch 29, wire 99, wire I99, wire I99, blade 51, contact 59, wire II5, wire II 9, wire II9, winding 19, wire I29, wire I2I, wire I22, wire I29, wire I99, wire H9, and wire I96 back to wire 93. As soon as relay 61 is energized relay 99 also becomes energized through the following circuit: from wire 92 through stop button 96, wire 99,wire III, wire II2, wire I24, blade 14, contact 16, wire I21, wire I29, winding 99, wire I29, wire I2I, wire I22; wire I29, wire I99, wire II 9, and wire I96 back to wire 99. As soon as relay 66 is energized it causes a maintaining circuit for itself to be completed which is independent of the relay 61. This maintaining circuit is as follows: from wire 92 through stop button 96, wire 99, wire III, wire I99, blade 19, contact 12, wire I, wire I29, winding 69, wire 59, wire II4, wire 91,

I29,.wire I2I, wire I22, wire I29, wire I99, wire leases the start button and manually opens the valve I5 admitting fuel to the combustion chamher where it is ignited by the flame of the pilot burner I9.

My system is primarily intended to give an alarm and warning in the event of a flame failure during operation ofthe system but not to give such an alarm or warning at any other time such 'as would tend to frighten personnel in the vicinity of the boiler unnecessarily. Alarms occurring at improper times needlessly inconvenience and annoy the personnel as well as militating against the ultimate purpose and effectiveness of the alarm. Thus if flame should disappear within the combustion chamber at any time during operation, the relay 55 will be deenergized as has already been explained and the above described circuits for the valves l9 and 29 and for the relay 61 and light 99 will be i'nstant- 1y deenergized. However, the maintaining circuit described above for relay 96 will not be deenergized until such time as the stop button 99 is moved away from the terminals 91 and 99. Im-

mediately upon the occurrence of the flame failure and deenergization of the relays 55 and 51,.

the red light 9| will come on and the bell 92 will begin to ring. The circuit for the bell 92 is as follows: from wire 92 through stop button 96, wire 93, wire III, wire II2, wir I24, blade 14,

contact 19, wire I94, contact 1|, blade 99, wire I95, wire I96, bell 92, wire I91, wire I29, wire I99, wire H9, and wire I96 back to wire 93. The

' circuitfor the red light 9| is as follows: from wire 92 through stop button 96, wire 99, wire II I,

opened as described the system is in readiness wire. II2, wire I24, blade 14, contact 19, wire I94, contact 1|, blade 69, wire I95, wire I99, light 9I,

wire I99, wire I22, wire I29, wire I99, wire III,

. cuit as described above.

' red light and the bell.

The system is now shut down but the valve i remains in open position. However, before the operator can again put the system into operation he must manually move the valve l5 into closed position so that the switch l'l will become closed to enable completion of the original starting cir- Th manual valve 15 provides an additional safeguard whereby if the automatic valve l3 should fail the operator will be unable to start the system and produce a spark in the combustion chamber which would ignite the gas pouring into the combustion cham-- her if the path of gas flow through the conduit I! were not obstructed. Moreover, after having caused combustion to be established at the pilot burner by means of the start button, the operator must manually operate valve I5 to admit the main gas supply and therefore he has the opportunity to assure himself that everything is in proper order before doing so.

When the system has been operating proper-'- ly and it is desired to shut it down, it is only necessary for the operator to push the stop button 85 which will deenergize the entire system including the relay 65. With both the relays 66 and 61 deenergized, both the red and green lights are out, and the bell 82 does not ring. Thus the disadvantage of many systems used in the past in that the alarm device sounded whenever the system was manually shut down is obviated. The system may of course also be shut down automatlcally by means of the pressure switch 28 or the low water cuts-.ofi '25. In the event of an automatic shut down from the switch 28 or low water cut-off 25, the alarm bell 82 will ring and the red light will come until the stop button 86 is pushed. Opening of switch '29 or switch 26will deenergize the entire system with the exception of relay 66 which, as explained above, after having once been energized has a maintaining circuit which is dependent only upon the stop butkm 86.

From the foregoing it will be apparent to those skilled in the art that I have provided a safety control system for combustion apparatus whereby a system can be started, operated, and stopped with the optimum in safety. The interlocking relationship of the controls and the arrangement of the signals and alarms is such that the danger of any exigencies arising such as would create a hazardous condition is practically eliminated. It is noteworthy that the system is of such a nature that the dangers normally attributable to the human element in the operation of these systems is reduced to a negligible factor. Only the barest kind of elementary knowledge and intelligence is required of an operator to safely and satisfactorily operate evn a complex system in which my invention is embodied.

It is to be understood that other types of flame detecting mechanism than the electronic device which} have disclosed can be used in the system. Moreover, my invention, particularly that portionof it comprising the alarm and signal relay mechanism, is ideally adapted to use in systems which are automatically started,'operated, and stopped. In such a system an automatic switch would of course take the place of the manual station 85 and the system would be started by closing such a switch and stopped by opening it. A relay switch such as the switch 58 would be used to shunt the switche ill and H after 5 completion of the original starting circuits.

The single form of my invention which I have disclosed is illustrative of one mode of practising and applying it, There are many changes which may be made in the invention and there are various forms which it may take and it is therefore to be limited only in accordance with the appended claims.

I claim as my invention:

1. In a system of the class described, in com bination, a combustion system comprising means forming a combustion chamber, means for supplying fuel. to said combustion chamber, means for igniting saidfuel, apparatus comprising con trol means for causing fuel to be supplied to said combustion chamber and for causing said fuel to become ignited, said control means also being operable to terminate combustion in said combustion chamber, means operable to check the capability of said igniting means of igniting incoming fuel, signal apparatus-comprising interlocking electrical relays associated with said checking means and a signal device, energization of one of said relays being dependent on said checking means, and another of said relays becoming energized when said one relay is energized, means whereby energization of said other relay becomes independent of said one relay when said other relay is energized, said other relay being independent of said flame detecting means,

and said signal device being arranged to give a signal when said one relay is deenergized and said other relay is energized.

2. In an alarm system for combustion apparatus in combination, means forming a combustion system, means forming an alarm device, a i

first electrical relay, a second electrical relay,

said relays being wired in interlocking relationship, means comprising a switch for starting said combustion system in operation, means whereby said second relay becomes energized upon assurance that combustion can safely proceed, means whereby said first relay becomes energized upon energization of said second relay, means whereby energization of said -dirst relay becomes independent of said second relay when said first relay is energized, means whereby said second relay is deenergized in response to an unsafe operating condition ofsaid combustion system, said first relay remaining energized and means whereby said alarm device gives an alarm when said second relay is deenergized and said first relay is energized.

3. In a signal system, in combination, means forming a signal device, a first electrical relay, 9.

second electrical relay, said relays being arranged vin interlocking relationship, means for energizing saidsecond relay, means whereby said first relay becomes energized upon energization of said second relay, said first relay being operable to remain energized independently of the energization of said second relay after becoming initially energized, and means whereby'upon deenergization of said second relay only. both relays cooperate in a manner whereby said signal device gives a signal.

4. In a signal system, in combination, means forming a signal device, a first electrical relay, a second electrical relay, said relays being arranged in interlocking relationship, means for energizing said second relay, means whereby said first relay becomes energized upon energization of saidsecond relay, said first relay being operable to remain energized independently of the energization of said second relay after becoming initially energized, means whereby upon deenergization of said second relay only, both relays cooperate in a manner whereby said signal device gives a signal, and means for deenergizing said first relay to terminate the signal given by said signal device.

5. In a system of the class described, in combination, a combustion system comprising means forming a combustion chamber, means for supplying fuel to said combustion chamber, means for igniting said fuel, apparatus comprising control means for causing fuel to be supplied to said combustion chamber and for causing said fuel to become ignited, said control means also being operable to terminate combustion in said combustion chamber, means operable to detect the presence or absence of flame in said combustion chamber, said last means. comprising means responsive to the electrical resistance of a flame in the combustion chamber, signal apparatus comprising interlocking electrical relays associated with said flame detecting means and a signal device, energization of one of said re- "lays being dependent on said flame detecting means, and another of said relays becomingtenergized when said one relay is energized, means whereby energization of said other relay become independent of said one relay when said other relay is energized, said other relay being independent of said flame detecting means, and

said signal device being arranged to give a signal when said one relay is deenergized and said other relay is energized.

6. In a system of the class described, in combination, a combustion system comprising means forming a combustion chamber, means for supplying fuel to the combustion chamber, fuel control means comprising a manually operable device for initiating the supply of fuel, a normally closed switch operable by said device and movable to open position when said device is operated to initiate the fuel supply, fuel igniting means, a manual controller in control of said igniting means, means whereby said fuel igniting means is dependent for operation upon said switch whereby said igniting means cannot be operated unless said manually operable device is in position to prevent the supply of fuel and said device must be manually operated to initiate the fuel supply after said igniting mean is in condition for igniting fuel. I

7. In a system of the class described, in combination, a combustion system comprising means forming a combustion chamber, means for supplying fuel to the combustionchamber, fuel control means comprising a manually operable device for initiating the supply of fuel, a normally closed switch operable by said device and movable to open position when said device is operated to initiate the fuel supply, fuel igniting means, a manual controller in control of said igniting means,

means whereby said fuel igniting means is dependent for operation upon said switch, signal means for indicating when said igniting means is in condition for igniting fuel, whereby said igniting means cannot be operated unless said manually operable device is in position to prevent the supply of fuel and said device must be manually operated to initiate the fuel supply after said igniting means is in condition for igniting fuel as indicated by said signal means.

8. In a combustion control system, in combination, a combustion chamber, an automatic device and a manually operable device controlling the supply of fuel to the combustion chamber, fuel igniting means, a manual controller for said igniting means, switches associated with said devices and circuit means whereby operation of said igniting means is dependent upon both said devicesbeing in position to prevent the supply of fuel, automatic means operable to respond if said igniting means is in condition to ignite fuel, and said automatic device being responsive to said automatic means.

9. In a combustion control system, in combination, a combustion chamber, an automatic device and a manually operable device controlling the supply of fuel to the combustion chamber, fuel igniting means, a manual controller for said igniting means, switches associated with said devices and circuit means whereby operation of said igniting means is dependent upon both said devices being in position to prevent the supply of fuel, automatic means operable to respond if said igniting means is in condition to ignite fuel, said automatic device being responsive to said automatic means, and signal means for indicating when said igniting means is in condition for lgniting fuel whereby said manually operable device may then be operated to initiate the fuel supply.

10. In a combustion control system, in combination, a combustion chamber, a manually operable device controlling the supply of fuel to the combustion chamber, fuel igniting means, a manual controller for said igniting means, a switch associated with said device and circuit means whereby operation of said igniting means is dependent upon said device being in position to prevent the supply of fuel, and automatic means operable to respond if said igniting means are in condition to ignite fuel, and an automatic fuel supply control device controlled by said automatic means.

11. In a combustion control system, in combination, a combustion chamber, a manually operable device controlling. the supply of fuel to the combustion chamber, fuel igniting means, a manual controller forsaid igniting means, a switch associated with said device and circuit means whereby operation of said igniting means is dependent upon said device being in position to prevent the supply of fuel, automatic meansoperable to respond if said igniting means are in condition to ignite fuel, an automatic fuel supply control device controlled by said automatic means and signal means for indicating when RUSSEIL n'wnmsm.

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