US2596729A

US2596729A - Fuel ignition system

Info

Publication number: US2596729A
Application number: US784280A
Authority: US
Inventors: See Walter George
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-11-05
Filing date: 1947-11-05
Publication date: 1952-05-13
Anticipated expiration: 1969-05-13
Also published as: FR974717A; DE964535C; BE485669A

Description

May l13, 1952 W, G, SEE 2,596,729

FUEL IGNITION SYSTEM wc.) mW-l in 20/ QQ, 0010/01/ l 5U ,j/MZZ/e/ZZH. Mie/1 (U/y@ Se@ May 13, 1952 w. G. SEE 2,596,729

FUEL IGNITION SYSTEM Filed Nov. 5, 1947 2 SHEETS--SHEE'I' 2 NoTE; THE swlTcHl-:s 49,52,5s,s|as2 ARE NoRMALLY oPEN. THE swlTcH 57 ls NoRMALLY cLosED.

NOTE: THE SWITCHES 52 8 57 ARE SLOW OR TIME DELAY (T.D) ACTION SWITCHES.

tion above the level of the liquid I3. The lower ends of the members 2I and 22 may be held in concentric relationship the one with respect to the other, and with respect to the outer member I5, by means of spacing collars 24 applied at the terminal ends of the members'2I and 22, which spacing collars allow for the free flow of fuel and air, respectively, through the concentric passageways I8 and 2G, into the member I5 below the spacing collars for delivery thence to the burner I2, through the casing I5.

The fitting 23, as shown more particularly in Fig. 4 of the drawings, may provide for the threaded or welded connection of laterally extending conduits I8 and 20', respectively for delivering fuel and air to the concentric channels I8 and 2U. Y

rlhe fitting 23 provides for the connection of the central channel I9, in an axial direction with v a chamber 25 formed at the end of the fitting 23 as by securing thereto, or integrally forming thereon, a preferably sleeve-like member 26, said member providing, as shown more particularly in Fig. 3, for the connection of the chamber 25 with a laterally extending pilot air supply pipev 21. The sleeve-like member 26 and the fitting 23 may,of course, be formed as separate elements secured together in any convenient or suitable fashion as by bolts, although, for the sake of convenience, it is preferable to form them as an integral unit. A preferably removable cover 28 may also be provided for closing the chamber 25, and said cover may provide an inlet chamber 29 connecting with a pilot fuel supply conduit 39 and communicating, as by means of a pipe 3l, through the chamber 25 with the interior of the channel i3 substantially below the chamber 25.

The principal elements of the burner thus com# prise the outer passageway I8 through which the main supply of fuel may be introduced to the purpose may comprise approximately 85% silicon carbide and 15% elemental silicon, by weight, the silicon carbide component being preferably in the form of a continuous reticular skeleton, in which the unit crystals are minute, uniformly distributed, and of cubic formation.

The lsilicon component preferably comprises elemental silicon which completely fills the interstices of the silicon carbide skeleton. Such material mayconveniently be produced in bars or rods of desired length and sectional configuration. Such bars will withstand exceedingly high operating temperatures without disintegration or the bar, at its opposite ends, to a pair of support the burner, the intermediate passageway 20 through which the main supply of air may be introduced, the pipe 3I through whicha supply of pilot fuel may be introduced into the central conduit I9 in the vicinity of the igniter I1, and there burned in air supplied through the conduit 21 and chamber 25 into the conduit I9. Upon ignition, the pilot fuel will burn at .the lower end of the conduit I9 in position to ignite main fuel within the outer member I5 below the lower end of the central channel I9. In submerged combustion equipment, it should be understood that the air and fuel must be supplied at pressures great enough to overcome the head pressure of liquid at the burner; and any suitable apparatus may be utilized for the purpose of delivering fuel and air at required pressures and volumetric rates through the conduits I8', 2U', 21 and 39. To this end any suitable or preferred air and fuel delivery devices may be employed, such delivery apparatus, where gaseous fuel is involved, preferably comprising means for supplying the fuel at desired pressure to the conduits i8 and 39, including electrically operated control valves in the fuel supply pipes I8 and 30, air supply being conveniently provided as by means of electrically controllable blower equipment and air iiow regulating valves in the

air supply conduits

23 and 21.

The igniter I1 preferably comprises a bar or rod 32 of material having a negative temperature coefficient of electrical resistance, the bar 32, to this end, preferably comp-rising a carbon compound suoh as silicon carbide. A bar suitable for stems 33 of electrical conducting material. These stems in turn may be mounted within and insulated from the fitting 23 in any suitable or preferred fashion. As shown, the fitting 23 provides an annular seat 34, facing into the chamber 25 at the end of the central channel I9 where said channel connects with the chamber 25. A mounting member, as shown more particularly in Fig. 6, is provided for supporting the stems 33 on the fitting 23. This mounting member or holder 35 may comprise any suitable preferably heat resistant electrical insulating material, such as porcelain, forming a central hub 36, defining an axial channel 31 and radially extending iianges 38 projecting outwardly of the hub 36. The outer edges of the iianges 38 are adapted to lit snugly within the walls dening the channel I9, and said flanges at their upper portions are formed with projecting lugs 39 adapted to t snugly within the walls of the chamber 25 and to rest upon the annular seat 34 whereby to support the member 35 within the chamber connected end of the channel I9. On one side of the channel 31 and on opposite sides of a lug 39 thereof, the holder comprises a body portion 40 having an outer surface adapted to snugly interiit with the inner surface of the walls defining the channel I9. This body portion is provided with a pair of axial channels 4I adapted to snugly receive andv hold the stems 33 and thus support the same in the fitting 23. The stems 33 have ends projecting upwardly of the holder 35 within the chamber 25, said ends being fitted with terminal means 42 adapted Yto electrically connect the posts 33 with electrical conductors 43 which may extend thence outwardly of the chamber 25, as through the pilot air conduit 21. The conduit 21, outwardly of the housing member 26, may be provided with insulated air-tight outlets through which the conductors 43 may extend outwardly of the pipe 21 for connection with any suitable source of igniter actuating electrical power.

vIt will be seen that the central channel 31 of the holder 35 may receive the fuel inlet pipe 3i therethrough to thereby aid in supporting the pipe 3I in axially centered position within the conduit I9, whereby pilot fuel may be delivered in said conduitV below the holder 35. The Webbed lsource, -to a selected maximum value.

or spider'conguration'of the vholder outwardly of the central hubV thereofV affords free pas" sage for the. deliveryjof pilot air into the conduit l I9 from .the chamber 25.

Theigniter: may be operated by ,connecting/the.'

conductors 43 witha suitable source of electrical' igniter energizingA power. Because of its negative temperature coeflicient of resistance, the igniterA element 32 operates as an automatic rheostat in that it' is' cold .and offers relatively high resistance .to current flow, when the actuating,

element, the resulting current now therethrough' increases progressively and proportionately'as the elementbecomes heated to igniting temperature, withconsequentdecrease in the resistance of the increases. due :to electrical current flowv element.. This characteristic enables the igniter,..

aswell as the. fuel. supply means to the burner,.

to be controlled in positive fashion by an exceedinglyv simple electrical control system, taking advantage of lthe aforesaid negative temperature. coeiiicient.ofresistance. of the igniter element.

As shown more particularly in Fig. 7 ofthe..

drawings, the. igniter element 32 may be energized from a transformer 44, the secondary orl output vwinding ofv which is connected with the conductors 43, the primary winding of said transformer being energized from any suitable source of electrical power 45 .through suitable protective equipment 46v and a preferably manually operable control switch 41 whereby the transformer 44 may be energized from the power source 45 upcn closure of the switch means 41. Since the igniter element has a negative resistance coeicient, said transformer 44, if desired, as a safety measure, may have impedance characteristics whereby to limit the current flow thereto, from the power As the igniter element 32 becomes heated toward ignition temperature, current flow in the primary circuit of the transformer 44 will materially increase from the minimum value, determined by the resistance of the element 32 when cold, to a predeterminable current ow value when the element 32 reaches its ignition temperature. Accordingly, theoperating coil 48 of a relay switch, having normally open switch means 49, may be interconnected in the energizing circuit cf the,

transformer 44 to cause closure of the switch means 49 as the element 32 reaches or exceeds its .ignition temperature. The switch 49 may be interconnected in series with the operating solenoid 5| of a fuel flow control device such as a valve 5|' disposed in the pilot fuel conduit 30 to.

flowcontrol device such as a valve trdisposed.

inthe lmain'fuel supply conduit {8to actuate. the .same for the -delivery of fuel upon closure ofthe switch 52'. Air blower or compressor means, or4 both; ma-y be `employed' to supply air or fuel also be\- energized for n'operationunder the control Upon closurercf theswitch-H; thev ignition element 32may,bebrought` to its igniting tempera'- turefand:iairand:pilotfuelA may be deliveredv through the conduits ^21 'and30 as soon as the igniterY element" has reached `its igniting temperature, whereby la pilotiiiamev may-.be established at the-lowerfendl-of the/central channelt I9 of the burnerfmy Afteral time delay vsuflicient `to assure` th'efestablishment of the pilotv flame, ymain lfuel and. air may be delivered'through'the conduits I3"V and'i2ll to'rthe 'burner mechanism, upon closureof the'switch52, the main fuel thus supplied Jbeing. ignited by gthe previously established pilo'tiiam'e'forv combustionvatV the burnerV I 2 Thercontrol'isystem shown'inl'ig.r 'I is exceedingly -simple vand* 'adapted'fo'r manual operation under. theicontrolofthe switch 41. The pilot. and j mainrburnerlames, having been established in the manner'described, will continue in operation.

barring `fai-lurenofthe. fuel;y air and electrical power'supplyruntil' the switch.41 is opened.I As

soonastheswitch41' isopened, `orupon failure of the'y 'electrical power 'supplyfthez coil48 will be.-

come nei-energizedfthe 'switches l49. .and 52 will.v open',"thereby^stopping the delivery of. main 'and pilot fuel and "air: to the combustion apparatus.'

Fig; *8, iiniradditionto the equipment shown in Fig.;V 7,- includes`l additional automatic switch means'ffor disabling 'the igniter control. circuitV after establishment of the pilot flame and the ignition of 'main'burner' fuel delivered through the conduit I8', whereby, after combustion has 30-and such air blower or compressor means may' been' establishedtheigniter may be` rendered inoperative withoutshutting off theA supply of .pilot or main-fuel.- l Totheseendsa relay switch mechanism^"54, havingn an operating'coil 55, is provided, saicl'operating 'coil 'being connected in parallel relationship-with respect to. the fuel control-solenoid'i53', under the control of the time delay closing switch52`. The switch 54 includes normally open-switch `means v56 and normally closed time delay opening switch means 51.. The time delay opening switch means`51 is connected in the operating circuit of the relay switch coil 48 and ofthe transformer 44, while the normally open switch 56 is connected in a circuit to control' the operating solenoid 58 of a relay switch 59, inorder to'actuate said switch'for the closure of its normally 'open.switchmeans 6| and 62 whenever the coil 58 is energized in .response to closureof'theswitch 56. The switches 5| and 62. respectively, areinterconnected in parallel relationship with. the switches 49 and 52, whereby,

to maintain,'in energized condition, the fuel and f air supply means 5| and 53 upon the opening of the establishment of .the combustion ,of.main

fuel'at the burner, the time delay opening switch 51 may operateto disable the igniter energizing transformeraswellas the solenoid 48. .Thereyuponthe switches 49' and 52will` open, but burner operation will be maintained thereafter by the switches 6| and 62, which remain in closed position, thereby maintaining the solenoids I and 53 energized to continue the fuel supply to the burner; and the switch 62 also maintains energy in the switch operating coil 55 to hold the switch 56 closed and the switch 51 open. The burner is thus maintained in operation, barring failure of the fuel, air, and electrical power supply, so long as the switch 41 remains closed. By opening the switch 41, of course, the entire apparatus will be restored to starting condition.

Obviously, numerous modifications may be made in the control system in order to accomplish refinements in the control of the air and fuel supply, as by the addition of control relay switches and other control equipment. Essentially, however, the present invention provides benefits owing from the utilization of the ignition element 32 having a negative temperature coefficient of resistance whereby-operation of the control system is accomplished in response to increased current ow in the energizing circuit of the transformer 45 and of the switch actuating coil 48. It is desirable, of course, and especially in the manual system as shown in Fig. 7, toprovide for limiting current flow to the ignition element 32, to a predetermined value appreciably in excess of that required to heat the ignition element to its igniting temperature. To this end the transformer 44 may conveniently comprise a current limiting transformer selected for the purpose of limiting at a desired value the current flow to the element 32.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

l. The combination, with fuel burning apparatus having associated pilot fuel delivery means and main fuel delivery means, of pilot fuel ignition means comprising an electrically operable igniter element having a negative temperature coefficient of electrical resistance, means for mounting said element in position to ignite said pilot fuel upon delivery thereof in said fuel burning apparatus, and an electrical system for actuating said igniter element and for controlling the delivery of main and pilot fuel to said burner apparatus comprising a pilot solenoid valve means for controlling pilot fuel, a main solenoid for controlling main fuel, means for energizing said igniter, a current responsive relay, responsive to current 110W to said igniter element, including pilot switch means for controlling said pilot solenoid when current flow to said igniter element reaches a predetermined value and main fuel switch means operable to control said main solenoid after a time delay interval following operation of said pilot switch means, and relay switch means operable by said current responsive relay for maintaining said pilot and main solenoids ,in operation and for disabling said igniter element and said current responsive relay after a predetermined time delay following operation of said current responsive relay.

2. The combination, with fuel burning apparatus having associated pilot fuel delivery means i and main fuel delivery means, of pilot fuel ignition means comprising an electrically operable igniter element having a negative temperature coeflicient of electrical resistance, means for mounting said element in position to ignite said pilot fuel upon delivery thereof in said fuel burning apparatus, and an electrical system for actuating said igniter element and for controlling the delivery of main and pilot fuel to said burner apparatus comprising a pilot solenoid for controlling pilot fuel, a main solenoid valve means for controlling main fuel, means for energizing said igniter, a current responsive relay, responsive to current ow to said igniter element, including pilot switch means for controlling said pilot solenoid when current ow to said igniter element reaches a predetermined value and main fuel switch means operable to control said main solenoid after a time delay interval following operation of said pilot switch means.

3. The combination, with fuel burning apparatus having associated fuel delivery means, of an electrically operable igniter element having a negative temperature coeflcient of electrical resistance, disposed in position to ignite fuel upon delivery thereof in said fuel burning apparatus, and an electrical system for actuating said igniter element and for controlling the de-v livery of fuel to said burner apparatus comprising a solenoid valve means for controlling the delivery of fuel, means for energizing said igniter, a current responsive relay, responsive to current flow to said igniter element, including switch means for controlling said solenoid when current flow to said igniter element reaches a predetermined Value, and holding relay switch means operable by said current responsive relay for maintaining said solenoid in operation and for disabling said igniter element and said current responsive relay, after a predetermined time delay following operation of said current responsive relay.

4. The combination, with submerged combustion fuel burning apparatus having associated pilot fuel delivery means and main fuel delivery means, of an electrically operable igniter element for said pilot fuel having a negative temperature coefficient of electrical resistance, disposed in position to ignite pilot fuel upon delivery thereof in said fuel burning apparatus, and an electrical system for actuating said igniter element and for controlling the delivery of main and pilot fuel to said burner apparatus comprising solenoids for controlling the delivery of fuel, current limiting means for energizing said igniteryand a current responsive relay, responsive to current flow to said igniter element, including switch means for controlling said solenoids when current flow to said igniter element reaches a predetermined value.

5. The combination, with fuel burning apparatus having associated pilot fuel delivery means and main fuel delivery means, of an electrically operable igniter element for said pilot fuel having a negative temperature coefficient of electrical resistance, disposed in position to ignite pilot fuel upon delivery thereof in said fuel burning apparatus, and an electrical system for actuating said igniter element and for controlling the delivery of main and pilot fuel to said burner apparatus comprising solenoids for controlling the delivery of fuel, means for energizing said igniter, and a current responsive relay, responsive to current fiow to said igniter element, including switch means for controlling said sole- 9 noids when current flow to said igniter element reaches a predetermined value.

6. Fuel burning apparatus comprising means forming concentric channels for the delivery oi fuel and air to a combustion chamber, including means forming a delivery channel extending from a receiving chamber to said combustion chamber, and a pipe extending axially of and having an end opening Within said delivery channel, a spider-like frame of electrical insulating material mounted in said delivery channel at said receiving chamber, said frame forming a central bushing for mounting said pipe Within said delivery channel, said frame providing spaced support bushings ofrset radially with respect to said central bushing, support stems of electrical conducting material mounted in said support bushings, an electrically operable igniter element mounted on and electrically connected with said support stems, within said delivery channel and adjacent the end of said pipe.

7. Fuel burning apparatus comprising means forming concentric channels for the delivery of fuel and air to a combustion chamber, including means forming a delivery channel extending from a receiving chamber to said combustion chamber, and a pipe extending axially of and having an end opening within said delivery channel, a spider-like frame of electrical insulating material mounted in said delivery channel at said receiving chamber, said frame forming a central bushing for mounting said pipe within said delivery channel, said frame providing 10 spaced support bushings offset'radially with respect to said central bushing, support stems of electrical conducting material mounted in said support bushings, an electrically operable igniter element mounted on and electrically connected with said support stems, within said delivery channel and adjacent the end of said pipe, a laterally opening supply conduit to said receiving chamber, and conductors for electrically energizing said igniter element electrically connected with said support stems Within said receiving chamber and extending outwardly thereof through said supply conduit.

WALTER GEORGE SEE.

REFERENCES oi'rnn The following references are of record in the file oi this patent:

UNITED STATES PATENTS Number Name Date 1,372,330 Bailey et al Mar. 22, 1921 1,495,855 Little May 27, 1924 1,940,127 Herthnecli Dec. 19, 1933 2,068,425 McCabe Jan. 19, 1937 2,095,253 Heyroth Oct. 12, 1937 2,291,805 Denison Aug. 4, 1942 2,296,686 Ragan Sept. 22, 1942 2,329,883 Eskin et al. Sept. 21, 1943 2,340,734 Clark ,Feb. 1, 1944 2,385,699 Fox Aug. 25, 1945 2,408,047 Cunningham Aug. 24, 1946 2.432.942 See et al Dec. 16, 1947