US3122196A - Control system for igniter torch - Google Patents

Description

J. A. SCHUSS Filed Aug. 25, 1961 CONTROL SYSTEM FOR IGNITER TORCH Feb. 25, 1964 INVENTOR JACK A- scl-luss BY @AT1-o NEY United States Patent $322,196 CGN i RGL SY-liE-M lGNlTER TQRQi-il .lack A. Schuss, Hartford, Conn., assigmor to Combustion Engineering, lne., Windsor, Conn., a corporation of Belaware Filed Aug. 25, wel, Ser. No. lSSSS 4 Claims. (Cl. 15S-2S) This invention relates to igniter apparatus in the form of auxiliary burners used as pilots or igniter torches for lighting other fuel streams delivered into a furnace as by means of tilting burners, or any other main burners, and it has particular reference to the control and indicating means associated with such igniter torches.

Where fuel, such as pulverized coal, is delivered into large furnaces, it is usual to have pilots or auxiliary burners using oil or gas to ignite said fuel. In addition warm up guns are generally needed in firing the first set of burners. As the furnaces get larger and larger, and thereby contain more burners, the problem of igniting these burners or pilots in a safe, emcient, and economical manner ecomes greater. There is an increasing tendency now towards remote operation of the burners from a main control board. In doing so, some indicating means must be provided at the control board to inform the operator in the event that the igniters are not operating properly, so that necessary repairs and adjustments may be made. Furthermore, some means must be provided for terminating the ow of fuel to the igniter torches or pilots when a flame is not established, and also to prevent fuel from being supplied to the main burners when the plots are not lit, to prevent the accumulation of a large combustible mixture within the furnace, which could lead to costly and dangerous explosions.

It is an object of this invention to provide a control for the igniter torches of a furnace, whereby the fuel to such torches is automatically terminated in the event that no flame is established.

lt is another object of this invention to provide a reliable .indication at a remotely located control board as to whether or not a llame has been established at the igniter torches.

it is a further object to test, or check out the flame sensing means prior to allowing7 fuel to iiow to said pilot, to make sure it is in proper working order, and will not give out an inaccurate signal.

lt is a further object to provide means `whereby fuel cannot be supplied to the main burner unless or until a llame exists at its corresponding pilot.

`lt is a still further object to accomplish the above by means of an economical, simple, and compact control arrangement, with a minimum number of control components required.

Other objects and advantages will become apparent from the following description of the illustrative embodiment of this invention when considered with the accompanying drawing, wherein:

FGURE l is a combined schematic and diagrammatic representation of the improved control apparatus of the present invention;

FIGURE 2 is a contact diagram for the master control switch which my new control system utilizes.

Looking now to FGURE l, lil depicts a pilot or igniter torch unit, containing a torch nozzle 12 to which oil and atomizing air are supplied, and an ignition means such as a spark plug ld, by means of which the fuel and air mixture is ignited. Combustion air is supplied by means or" pipe 13. An igniter torch unit such as the one shown is provided for each main burner existing in the furnace, and is positioned adjacent each main burner, so that the llame therefrom can ignite and/or stabilize ICC the combustible mixture issuing from the main burner nozzle.

The present control system is arranged so that all of the igniter torches or burners can be started up by an operator from a central or distant location. The control system comprises a master control switch 2?, which can be mounted on a control panel located remotely from the furnace. The control switch 2li has four positions in which it may be placed, these being olii trip, operate and ignite :The control switch 2Q consists of a number of cam actuators which will close various ones of the switch contacts A1, A2, A3, A4, B, C, D, and E, depending in which position the switch 29 is placed. The control illustrated is that which Iwould he used to control the ring of four igniter torches, such as a set which would be used to light and/or stabilize tilting tangential main burners, one of which would be mounted in each of the four corners of the furnace.

The broken lines 30 and all indicate the control cabinets located adjacent to two of the pilot torches, two more not being shown. The components of all four of the control cabinets are actuated by master control switch Ztl. A suitable source of electrical energy 5t) is provided. The four control cabinets, each adjacent to one igniter torch, are identical with one another, and contain the same components. The components of control cabinet 3i? will now be described, it being understood that each of the other three are identically constructed.

The control cabinet 313 houses a mechanical latch relay mechanism 6l?. The mechanical latch relay mechanism et? consists of coils 62 and 116, one normally closed switch 72, and four normally open swiches 76, 7S, t), and 82. Switches 72, 76, 78, 89, `and 32 are mounted on a rod S3, which is biased to the left by tension spring 104 when neither of the coils 62 or lle is energized. The rod S3 is pivotally connected to arm H8, to permit longitudinal movement thereof. Arm 83 contains a hook T108 on its right end which coacts and engages with the hook on member 106 to hold it in its rightward position when coil 62 is energized. Arm lilo is pivotally connected to fixed member 112, and tension spring llurges the arm downwardly so that it normally is supported on rest lill. VJhen coil :116 is energized and lifts hook arm ille upwardly, spring M34 pulls rod 33 to the left again.

Also contained within control cabinet lill is a transformer 66 for energizing the spark plug or ignition means la, and solenoids 843 and b3 which actuate oil valve 36 and air valve 9G, respectively, which controls the supply of oil 'and atomizing air to the igniter torch lll. Switch 92 is actuated by llame sensing means 95 to close either right hand contact llli, or left hand contact ltlZ. Flame sensing means 95 consists of a diaphragm 94 which is exposed on opposite sides to the static pressure which exists at two xed points within torch l@ by means of air lines 96 and 98. When no llame exists in the igniter torch, there is little or no pressure differential existing between lines 96 and 9S, and switch 92 is biased to the right to close contact lili?. When a flame is present, the static pressure in line 93 increases, thus moving switch 92 to the left to close contact HB2.

indicating light L1, which is mounted on the control panel along with control switch 2li, gives a visual indication to the operator whether or not a flame exists at igniter torch lil. Lights L2, L3, and L4 perform the same function for the other three torches controlled by switch 2t?.

The operation of the control system will now be described. When it is desired to start up the furnace, and ignite the pilot torches, the operator moves control switch 2@ from the olf position to the ignite position. This closes contacts C and E by means of their associated cam actuated switches. Closing contacts E completes the circuit to energize transformer e6 through conductors 64 and 68, to produce the necessary spark at spark plug or ignition means 14. If at this time the llame sensing means 95 is in proper working order, indicating a no iiame condition of pilot lil, switch 92 will be biased to the right by compression spring 9i, closing contact liil. If this condition exists, then operating coil 62, will be energized through contacts E, normally closed switch 72, Contact 100, and conductor 68.

Energization of operating coil e2 pulls arm 118 and also rod 83 to the right, thereby opening the normally closed switch 72 and closing the four normally open switches. Although this deenergizes coil 62, by opening switch 72, rod 83 is held in its right position by engagement of hook with the hook on arm lilo. Closing of contacts C immediately energizes solenoid 83, thereby opening air valve allowing atomizing air to flow to the igniter torch. The air from i3 to support combustion is controlled by other means. Movement of rod 83 to the right also closes normally open switch 73, energizing solenoid 3ft, thereby opening oil valve 86 to allow fuel to ilow to the igniter torch lil'. With air and fuel thus flowing to the torch, and with the ignition means i4 thus being energized by means of transformer 6o, combustion should take place in the pilot burner lo. Establishment of a flame creates a pressure diierential in lines 95 and 93 to move switch 92 to the left, closing contact i432. Since switch 8@ is now closed, L1 on the control panel will light up, current owing througa contacts C and conductor 121 to L1, the circuit being completed through conductor 122, switch Sii, Contact lili. and conductor 63. This indicates Vto the operator that combustion has taken place at igniter torch lil, and that a llame exists there. All of the above operations take place automatically within a few seconds if everything works properly, when master control switch 2@ is moved 4to its ignite position.

AfterY a predetermined short tifne, possibly 2 seconds, switch 2i) is automatically moved to its operate position when the operator releases it. This can be accomplished by a tension spring 22 which will return switch 20 to the operate position when the handle is released. ln this position, contacts E are opened, and contacts B and D are closed, with contacts C also remaining closed. Opening of contacts E deenergizes the ignition transformer 6o, thus extending the useful life of spark plug 14 by using it as little as necessary. Closing of contacts B completes a circuit through switch 76 and conductor 12S to a switch corresponding to switch 75 in each of the other three control cabinets for the other three igniter torches. if a llame has been properly established in each of these igniter torches, then relay is energized, thus closing a pair of switches which complete an interlock systei These switches could when closed, for example, permit the start of the coal mill and coal feeders l-ii, which supply pulverized coal to all four of the associated main burners. Since the circuit contains each switch corresponding to switch 7o ofV each control cabinet in series, plus contact B of the control switch which closes in the operate position, it is obvious that if one of the igniter torches failed to establish a llame by the time the control switch is released to its operate position, associated relay contact 7e or one corresponding to it would reopen (if previously closed on satisfactory dierential pressure checkout) and hence relay lil will fail to stay energized.

With contacts D closed when control switch Z9 is in the operate position, if the flame should go out or fail to be established at burner lil, then a circuit is completed to reset coil llo through contacts D, switch 82, contact lilo, and conductor Energization of coil llo lifts arm '1% upwardly disengaging the hooks, and thus allowing spring lhl to move rod 53 and the associated switches to the left, to their normal or original positions. If this happenathe light L1 goes out, and the solenoid 54 of the oil valve is deenergiledby opening of switches 3% and 7S,

respectively. Then in order to start up again, it would be necessary for the operator to again place control switch 2li in its ignite position, and if it failed again, he should check to see where the trouble is.

When orderly shut down of the ignition system is desired, the control switch 2li is placed in the trip position thereby closing contacts A1, A2, A3 and Ag, opening contacts E, with contacts C and D remaining closed. A circuit through the reset coil 116. which bypasses the differential pressure switch E2 'oy way of switch 82, conductor 124- and contacts A1, is established. The result is closure of the oil valve S6 and the de-energization of the indicating light L1, indicating that the re at burner l@ is out. Switch S2 opens upon mo` ement of rod S3 to the left, thereby deenergizing reset coil llo, and switch 72 closes, resetting the circuitry to operating coil 62 for the next operating cycle. With no power required to feed any of the ignitor control components, the master control switch 2@ can now be placed in the oil position.

Numerals i3d, l32, and 134 indicate conductors which extend to the other three control cabinets from contacts E, D, and C, respectively, so that these controls operate in the same manner as the one described. Contacts A2, A3, and A4 perform in the same way as does A1, and lights L2, L3, and L., indicate the llame condition for their corresponding burners or pilot torches.

While a control system has been described where the torches are associated with coal tired main burners and the igniter light oil of all four igniters is a prerequisite for the start up of an associated coal mill, this control system can equally as well be adapted to an arrangement whereby each individual ignitor is interlocked with an associated oil or gas red main burner. Also, any number of igniters can be controlled by a single master control switch 2li. lf gas, rather than oil is kused as a fuel for igniter torch lil, then the atomizing air is not necessary,

and air valve 96 and its associated solenoid 88 could beV omitted from the control cabinets.

The integral opera-tion of a group of four igniters is shown controlled by manipulation of a manually actuated switch 2n; however, the arrangement can also be adapted to operation by a digital or analog computer supervised control system where switch 2h is superseded by electromagnetic relays or static switching devices, the switch 2l) then being retained to provide an alternate mode of operation when control is switched to hand operation. If this were done, the signal energizing the indicating light L1 could also be used to provide a feedback pulse, to automatically clear the computer for the next step in the operational sequence. Whatever, the mode of operation, whether m ual or automatic, the same internal igniter cabinet conti l arrangement as illustrated would be used.

The advantages of my control system should now be apparent. The system provides an automatic check out or test of the llame sensing means to make sure it is in proper working order before an attempt is made to ignite the pilot or igniter torch. For example, if switch 92 is stuck in its position closing contact 15192, cr the diferential pressure diaphragm is faulty so as to hold the switch 92 in a position other than in its right hand position closing contact lilii, then when control switch 29 is moved to its ignite position, operating coil e2 will not be energized, and the subsequent sequential operations will not take place. If such condition arises, the fuel valve 86 will not be opened, nor will L1' light up, and the operator will thereby be notified that the llame sensing means is not functioning properly. ln this manner when L1 lights up, it informs the operator of two things: (l) that the differential pressure switch and the llame sensing means is in satisfactory operating condition; and (2) that a flame has been established.

Other'advantages are that under no conditions will fuel be supplied to the igm'ter torch for more than a few seconds without the presence of a flame; the ignition transformer is energized only for a short period of time when the control switch is in the ignite position, which contributes to the long life of the sparl; plug; and the energization of the coils of the mechanical latch relay mechanisrn is of momentary duration only, thus preventing any great heat addition to the control cabinets from this source.

While I have illustrated and described a preferred embodiment of my novel control organization it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What I claim is:

l. An igniter torch and main burner control system comprising in combination, a main burner, means to control the flow of fuel to said main burner, an igniter torch for said main burner, means to control the llow of fuel to said igniter torch, ignition means for the fuel of said igniter torch, flame sensing means for detecting whether or not a frame is issuing from said igniter torch, means for testing the frame sensing means to determine whether or not it is in working order prior to allowing fuel to flow to either the main burner or the igniter torch, means for positioning said fuel controlling means of the igniter torch such that fuel is supplied to said igniter torch only if the llame sensing means is in working order, said flame sensing means being capable of stopping the flow of fuel to said igniter torch in the event no llame exists after said ignition means have been energized and fuel is flowing to the burner, said main burner fuel ow control means allowing fuel to ow to said main burner only if and after a frame exists at said igniter torch.

2. The igniter torch and main burner control system of claim 1, including an indicating means responsive to said llame sensing means which indicates whether or not a llame is present at said igniter torch.

3. The igniter torch and main burner control system of claim l, whereby said flame sensing means includes a pressure differential actuated means which is responsive to the static pressure existing at two spaced points within said igniter torch.

4. In a burner control system, a burner, means to control the ilow of fuel to said burner, ignition means for the fuel, flame sensing means for detecting whether or not a flame is issuing from said burner; an electrical system comprising a rst circuit having a transformer capable of energizing said ignition means and a first switch means E in series therein; a second circuit having said first switch means E, a second switch means 72, a first relay 62, and a third switch means 92, 143i) in series therein; a third circuit having a fourth switch means C, a fifth switch means 73, and a solenoid capable of actuating said fuel control means in series therein; a fourth circuit having a sixth switch means D, a second relay 116, a seventh switch means 32, and said third switch means 92, 10G in series therein; a member to which said second 72, fifth 78 and seventh 82 switch means are attached; means biasing said member to a first position in which said second switch means 72 is closed and said fifth 78 and seventh switch means are open; latch means for holding said member in a second position in which said fifth '78 and seventh S2 switch means are closed and said second switch means 72 is open; said second relay 116 when energized being capable of releasing said latching means so that the member will he biased to said rst position; said first relay 62 when energized being capable of moving said member to its second position; said third switch means 92, lill) being closed when no flame is present in the burner; said flame sensing means being capable of opening said third switch means 92, lili) when a llame is present in the burner; and a control switch means 20 which in a hrst position closes said first E and fourth C switch means, leavsald sixth switch means D open, and which in a second position closes said fourth C and sixth D switch means, leaving said first switch mems E open; whereby said burner can be ignited and put into operation by movement of said control switch means 2@ to its first position, followed by consequent movement to its second position.

References Cited in the file of this patent UNITED STATES PATENTS

Claims (1)

1. AN IGNITER TORCH AND MAIN BURNER CONTROL SYSTEM COMPRISING IN COMBINATION, A MAIN BURNER, MEANS TO CONTROL THE FLOW OF FUEL TO SAID MAIN BURNER, AN IGNITER TORCH FOR SAID MAIN BURNER, MEANS TO CONTROL THE FLOW OF FUEL TO SAID IGNITER TORCH, IGNITION MEANS FOR THE FUEL OF SAID IGNITER TORCH, FLAME SENSING MEANS FOR DETECTING WHETHER OR NOT A FLAME IS ISSUING FROM SAID IGNITER TORCH, MEANS FOR TESTING THE FLAME SENSING MEANS TO DETERMINE WHETHER OR NOT IT IS IN WORKING ORDER PRIOR TO ALLOWING FUEL TO FLOW TO EITHER THE MAIN BURNER OR THE IGNITER TORCH, MEANS FOR POSITIONING SAID FUEL CONTROLLING MEANS OF THE IGNITER TORCH SUCH THAT FUEL IS SUPPLIED TO SAID IGNITER TORCH ONLY IF THE FLAME SENSING MEANS IS IN WORKING ORDER, SAID FLAME SENSING MEANS BEING CAPABLE OF STOPPING THE FLOW OF FUEL TO SAID IGNITER TORCH IN THE EVENT NO FLAME EXISTS AFTER SAID IGNITION MEANS HAVE BEEN ENERGIZED AND FUEL IS FLOWING TO THE BURNER, SAID MAIN BURNER FUEL FLOW CONTROL MEANS ALLOWING FUEL TO FLOW TO SAID MAIN BURNER ONLY IF AND AFTER A FLAME EXISTS AT SAID IGNITER TORCH.

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