US2396146A - Flame contact unit for burner control systems - Google Patents

Description

March 5, 1946. H A WATER 2,396,146

FLME CONTACT UNIT FOR BURNER CONTROL vSYSTEMS Filed June s, 1942 2 Sheets-Sheet l H TTPNEY.

2 Sheets-Sheet 2 H. A. ATWATER- Filed June 3, 1942 March 5, 1946.

Patented Mar. 5, 1946 FLAME CONTACT UNIT'FOR BURNER CONTROL SYSTEMS HarryA. Atwater, Kansas City, Mo., assignor to Combustion Equipment Company,`Kansas City,

Mm, a partnership Appiicataonine 3, 1942,-ser1'a1'No. 445,559

. 11 claims. (c1. 15s-2s) The present inventionr relates to apparatus de-- signed to control the supply of fuel to burners' of a type producing a flame in the combustion process; and aims to devise a novel and improved control means utilizing such combustion' flame as withstand the entirerange of temperatures which l may be encounteredl in gas burner operation,` and so arranged as to render the circuit definitely responsive to flame.'V conditions within a substantial space or area traversed by the main flow of gas from the burner; and where thisspace'or area is traversed by a pilot lighting flame the arrange'- ment is such that said lighting flame can not reach or contact, the flame-contact structure withoutv having first traversed this intervening. space or area, the object beingV to preventa possible grounding or completion of the .control circuit through any Vllame ,contacts to which the mainv gas ow has not also been subjected.

A further object of the invention is to provide and so arranged as' to` provide' a compact and practically fixed assembly which is not likelyto ibe disturbed or materially disarranged by workmen in making installationsl embodying the' apparatus.

It isY further sought to devise sucha construction as will provide for all necessary adjustments for'properly varying the flame contact structure With relation to the combustion face ofthe burner, as required for' efficient control operation, and also for enabling thev flamercontact unit to be located in operative position at either side of they burner.

in operative. relation to the *combustion face of a' gas burner; 1 1

FigurefZ is a front elevation of the same on asomewhat larger scale;

Figure 3 is a horizontalflongitudinal sectional View, representing a section taken' on the line 3-i3'0f Figure 2;, f Y

Figure 4 is 'avertical longitudinal sectional view, representing a sectiontaken on the line 4-4of Figure 3; p

Figure 5 is an enlarged sectional detail view, representing a section taken on the line 5-`5 ci?V Figure 3; i I

Figure Gis asimilar sectional detail view, representing a section as indicated by the line lie-6' of Figure 4;

Figure-7 isan enlarged sectional detail view, indicating a secton'taken on the line 'l--l ot Figure 6;.and

Figure 8 is a frontl elevation similar to the view shown in Figure 2 butillustrating the name'r contact structure and other partsjof the unit assembled inoperative position at the opposite side of the burner. Y

.shutting on the fuel supply as an emergency or' safety feature, in connection with boiler operations and the like, is a well-known adjunct characterizing combustion operations, and there are alsccertain well-known and conventional types of control systems for liquid and gaseous fuel burner installations which utilize suitable relay devices in electric control circuits including the combustion name as. a part of the circuit; The relay initheseY control circuits is ordinarily provided with a terminal connected withv the burner which is grounded, and also a terminal having a conductor adapted to complete the circuit through either. the combustion flamev of the burner, or its pilot llame, for which purpose said conductor may includeV What is sometimes called a flame electrode designed to be' enveloped by the llame and thereby complete' the circuity on contact of the flame with the exterior face of theburner.

Obviously a pilot burner and flame are not indispensable to `such a control system, since the main gas burner may be lighted either manually or by some rsuitable automatic means, in which case the controlfwould function simply to cut off the fuel supply in the absence of any ame for completing the control circuit.

Some ofthe defects characterizing these prio commercialv types ofinstallations may be noted as instigating efforts toward the present improvements, viz., the inability of critical parts of the construction to withstand the higher furnace temperatures which are frequently encountered; the absence of any unitary or composite design of ilame contact element and pilot structure with more or less fixed relationships not likely to be disturbed on being actually installed and at the same time providing for an installation in which the pilot flame must actually traverse a material portion of the path of the main burner gas flow before completing the contro-l circuit; and moreover, the lack of sufhcient flexibility of design of construction to permit all requisite adjustments required by the demands of any particular burner installation while retaining all the important advantages contemplated by the present improvements. It is quite apparent that apparatus having one or more of these defects will naturally fall short of satisfactory performance; for example, any so-called iiame electrodes which will not withstand the required temperatures will either gradually burn away or become pliant and sag down out of operative position, and therefore no longer function. Likewise, where the pilot structure is not incorporated as an integral or component part of the flame-contact controlling unit but is simply a pilot structure roughly adapted to the rest of the construction, such adaptation is of course left to the installing workmen, who

can not be expected to understand or to make` provision for all the requirements of a proper pilot installation of this type; and this is particularly true as regards lack of any provision for one of the most vital features characterizing the present invention, i. e., the elimination of any chance of the pilot flames completing the control circuit or rendering it operative without having i'lrst traversed a suicient extent of the main gas ilow from the burner to insure ignition thereoi prior to such completion of the control cir cuit.

Referring now to the drawings in detail, the improved construction comprises a pilot casting I formed with an interior partition Il which provides support for a conventional sparkplug device I2 and a pilot gas supply pipe I4, while at one side of said partition is formed a pilot chamber I5 having a lateral pilot flame opening I5 for discharge of the pilot flame transversely across the adjacent burner orifices I1 in the front or combustion face of the gas burner block IB'- as illustrated in Figure 2. For this purpose the unit is so mounted as to locate said pilot flame opening I6 slightly forward of the burner orices I1; and the mounting of the unit in this position is facilitated by providing the shoulders on said casting I0 for engagement with the front face of the'burner; and provision is also made for bolting the casting I0 against the side of the burner, through the medium of -bolt openings as indicated at 22 (see Figure 4) One end of the gas supply pipe I4 is connected with the partition II and clamped by means of a nut I9 in communication with a discharge chamber 23 formed in said casting I0 and fitted with an orifice element 24, the shank of which is screw threaded (as indicated at 25) for removable connection with said chamber 23. 'Ihese orice elements are thus interchangeable and are provided with any desired shape or size of oriflces 26 for producing the required form of pilot llame, to be projected laterally through the opening I 5; this flameshould preferably be of wide and fan-shaped extent projected in a vertical plane across and in front of the adjacent burner oriices I1.

Upon the top of the pilot casting IU is mounted a. block 3| of suitable refractory material, in such relation that the outer or front faces of the block and casting register or lie flush with each other; and to facilitate the proper assembly of the parts in this relation the block 3l is formed with a groove 32 for engagement with a rib 33 on the exterior of the casting IU. Moreover, since this casting may be reversed for the purpose of directing the pilotame in either of two opposite directions (as may be required for mounting the unit on either side of the burner), the positioning rib 33 may accordingly be formed on both the upper and the lower face of said casting, for engagement with the groove 32 in either of the operative positions of the pilot unit.

The inner or rear side of the block 3i is formed with a cove or recess 35 terminating short of the top of the block (see Figure 4) and the top portion of this recess 35 communicates with a horizontal and daring or fan-shaped passage 31 opening upon the front face of said block (seeFigures l, 4 and 8).

This recess 35 provides a sheltering cove or housing for a supporting structure for the parts of the flame-contact unit, all of which will now be described This supporting structure comprises a flanged base member 40 which is anchored by screws 42 to the top of the pilot casting ID, and is also formed with a smooth central opening 43 for accommodating a vertical screw 44 having a head portion 45 which is housed within an opening or recess in the lower face of the base member 40, as illustrated in Figure 5. Carried by the upper end of the screw 44 is a substantially spherical element 48 formed with a shank portion 49 tapped for engagement with the upper end of the screw, and also formed with a. horizontal bore for accommodatinga mica rodprotecting sleeve 54. One end of the bore 52 is reamed out, as indicated at 55, for asbestos ber packing material `56 which is 1retained by means of a packing gland nut 58 iitted over one end of said sleeve 54. 'Ihe sleeve 54 is thus mounted for pivotal movement horizontally about the axis of the screw 44, butmay lbe secured in any set position by means of a suitable clamping screw 60.

Removably mounted in the sleeve 54 is a refractory quartz Atube 62 having one of its ends projecting out through the opening or passage 31, while the intermediate portion of the tube is provided with a knob formation 63 serving as a stop element in connection with the insertion of the tube into the sleeve 54 and adapted, in the pivotal movement of said tube, to engage the sides of the passage 31 for limiting such pivotal movement and thereby prevent any of the parts at its inner end from making any contacts which might result in grounding of the electric circuit.

This tube 62 serves as a support for a rod 65 of highly refractory silicon carbide material, known commercially as C'arborundum and of special dense form; this rod protrudes from the opposite ends of the tube 62 and at one end carries a copper wire gauze strip 61 for detachable connection with' a clasp element 68 which is attached to a conductor 10 leading to the relay control unit (not shown) of the system. The other end of the rod 65 has a reduced neck portion (as indicated at' 1I) designed for the support of the llame contact element in suspended position in front of the burner openings I1, as illustrated in Figures l, 2 and 8.

This llame contact element is of substantially .ures 1 and 8).

' Aagarre, 114cright-angular shape, constructedi of the samev highly refractory'materi'alv as the rod 65 andcom'..` prising an upright comparatively heavier bar 14', the head portion 15 of which is providedwithtwok sets of rod-receiving openings l5 to permit mounting of the contact member' in either ofv two different positions at right angles to each other, upon the end of the rod element 65 (compare Fig- The lower end ofthe bar 'I4l car.r ries a slender horizontallyprojecting rod 'I8' (constituting the name contacting portion)` and also a knob or enlargement 8!)` as a means for counterbalancing said rod i8 and maintaining the latter in approximately horizontal position;

A casing or housing 82 isattached tothe-rear if end of the pilot casting I0 for enclosing the pilot gas: supply pipe lilv and also the'lead or conductor 83-to the spark plug element" i2, said pipe i4 and lead 83 being held in spaced relation by suitable clamping' means 84 (see Figure 3).

A top cover casing 86 is mounted upon and attached by screws- 81 to said casing 82 and also fits over the reduced portiont' on the rear face of the refractory block 3l, which is also formed withl a channel or groove 88 for receiving a lip or ilange 90 at the corresponding end of said casing 86 as illustrated in Figure 4, thereby cooperating with the groove 32 and rib 33 to maintain said block 3| in its proper position. Atthe same time the clearances provided are amplefor all necessary expansion and contraction of the construction resulting lfrom the operation of they burner.

If necessary, extra housing ,extensions 82 as well as cover extensions 86' maybe added to correspond with the thickness of thev setting. wall 92 inwhich the burner is being installed; and said casing and housing parts will of course be equipped with' whatever interior clamp devices 93 may be needed for the proper support of the lead or conductor 1D (see Figures 3 `and 4) Also in the usual installation the pilot box or casting I0 will be suitably protected from direct furnace temperatures by providing additional re brick protection as indicated at 94, at the front ci A said casing, as illustrated in Figures 3 and 4.

As an aid to facilitate installingthe unit in its proper operative position, an extension lug or bracket 9S is suitably fastened, as by means of a bolt 91, to the rear end of thev casing structure 86 or 86', as a stop for engagement with the inargin of the wallopening 98 provided in the furnace wall for accommodating the unit;or`for engagement with any suitable liner: (not shown) which may be providedfor housingthe unit with..` in said wall opening. It may be further explained that. as a matter of practice,` provision. is usually made in th'e way of either a side window or opening adjacent the front face of the burner or a passage alongside the wall opening 98 (to be" lled with loose brick) for. obtaining access to the front end of the unit as required for removing the flame ContactY element 14 in the making of any repairsor adjustments which may necessitate withdrawing th'e kunit from the wa-ll; in this operation, after the removal of said contact element 14, the screw 60 is loosened and the supporting structure (including the tube 62). swung burner oriiices that saidv rod does not project into the path of the pilot flame except ati some distance from the pilot chamber I5, so that the. pilot lighting flame must iirst traversel a materialA expanse of the main gas flow from the orifices l1 before contacting the end of the rod 18 which' is in-v proximity to the burner face, through which the control circuit is to'be closed or groundedseeA Figure 3. Therefore, in th'e operationV of the burner it is clear that such arrangement' pre.-v cludes any possibility of the pilot lighting flame itself, alone, operating to close the circuit (that I of the chief causes of the disastrous explosions. Y

often resulting fromfdelayed ignition, or from. total failure of ignition, andthe consequent accumulation of gas, is effectively eliminated.

Moreover, this same certainty' of the desired Operation is assured for each installation, regardless of whether the same degree or skill is employedr on each job, because of the same uniform design or set relationship of the pilot and namev contacting parts being embodied in each and every unit for producing the same operative relationship of those parts, with relation to the face of the burner. Consequently the,l critical relationship necessary for the purposes of my invention cannot be so varied or changed as to affect or interfere with the proper operation of the control circuit by careless or indifferentworkmen,

;. for it is of course obvious vthat once the flame.

contact parts are set, with the support therefor moved into either of the supporting positions shown in Figures 1 and 8, theliame contact element 'I8 can not be reached by the pilot flamel except by the passage of said name across some material portion of the main gas ow.

Proper and continuously satisfactory operation is further assured by the character of materials used for the name contact elements for withstanding temperatures which. are much higher than those designed to be endured by the conventional metallic types of electrodes employing various alloys not adapted to withstand furnace temperatures vmuch in excess'at 2100" to 22.00". The supporting rod 55 andiiame contact structure 'I4- '58 being of silicon carbide material which has a melting point upwards of 2700 F., and said rod being mounted in the quartz tube 62, this provides not only insulation but also very effective resistance vto all such temperatures as are clevel-V oped in any of the well-known commercial processes. The mica tube 54 provides an additional insuating element between said parts andthe supporting structure iS-49, which is in turn shielded by being housed within the cove 35 of the refractory block 3 l, Such a construction'protects these elements of the control circuit from the disintegrating effects of the intense furnace heat, and furthermore, the Carborundum mate-l rial comprising the rod 62 and the llame contact structure being, as indicated, of special dense form, sa id elements are adapted to withstand such softening action as would cause them. to droop and sag out of proper operative position.

Another function served by the quartztube 6i" is as a reinforcement for the special' refractory rod 65, to helpt carry the load supported. by its outer end. The reduced neck portion. 'llA on said' outer end of the rod E5, insertable into. either of they two'sets of. openings. 'lejoi the'.flarnecop'- tact shape 14, affords means for quick and easy shifting of the latter into either of the two alternative positions illustrated in Figures 1 and 8, and without vany danger of displacement from such operative positions. In this connection it may be explainedthat the simple gravity contact between these elements is entirely sufficient for the proper functioning of the circuit, which is designed `to operate normally with a relatively high resistance factor.

Finally, it is pointed out that the use of flame contacting elements of extremely high refractory properties is an important feature of improvement in the present invention, for the reason that the electrode devices of prior constructions are not adapted to withstand temperatures as high as those to which the flame contact elements of the applicants arrangement are subjected. As a matter of fact it is significant that prior control systems have recognized the limitations of their electrode devices by actually so locating them as to avoid subjecting them to the maximum temperatures involved, and it is this very practice which has resulted in those defects in operation hereinbefore pointed out, especially that outstanding defect which is due to failure to locate the electrodes or flame-contacting elements in position to require the pilot lighting flame to traverse a suflicient extent of the main gas flow to insure ignition of that main gas ow a determining factor in the establishment of the contro-l circuit. From this it is very apparent that thc high refractory properties of the applicants flame contact elements constitute an important and essential characteristic of the present invention.

It will therefore be recognized that I have dcvised a practical and efcient arrangement and construction of apparatus which is effective for carrying out all the desired objects of my improvements, but that the described construction may nevertheless be modified in various minor respects While still embodying the essential principles of my invention. I therefore desire to be understood as expressly reserving the right to make all such changes or modifications as may fairly be deemed to fall within the spirit or scope of my invention as dened by the following claims.

Having thus described my. invention, what l claim and desire to secure by Letters Patent is:

1. In a flame responsive circuit for controlling burner operations, the combination with a burner block having a combustion face provided with one or more gas discharge orifices, of means for directing a lighting ame in a path transversely across and in contact with the combustion face of the burner` and a circuit connection provided with a flame contact element also projecting a material distance across the path of the main gas llo-w in the same general direction as said lighting flame but farther away from the face of the burner for 5 bypassing the initial portion of said llame, said Contact element terminating at a point within the path of said lighting flame whereby said circuit is closed through said llame to the burner.

2. In a flame responsive circuit for controlling burner operations, the combination with a burner block having a combustion face provided with one or more gas discharge orifices, of a pilot structure operative to direct a lighting flame in a path across and in contact with the combustion face of the burner, and a circuit connection provided with a flame Contact element supported by said pilot structure and projecting across the path of the main gas flow but bypassing the initial portion of the path of said lighting llame and terminating in close proximity to the face of the burner, said contact element having refractory properties effective for withstanding temperatures greatly in excess of 2200 F.

3. In a flame responsive circuit for controlling burner operations, the combination with a burner block having a combustion face provided with one or more gas discharge orifices, of a pilot structure mounted in a fixed relation to the burner and operative to direct a lighting flame in a predetermined path transversely across and in contact with the combustion face of the burner, and a circuit connection provided with a flame contact element and refractory supporting means mounted on said pilot structure and carrying said flame y Acontact element with the latter projecting a material distance across the path of the main gas now in the same general direction as said lighting flame but farther away from the face of the burner for bypassing the initialfportion of said llame, said contact element terminating at a point within the path of said lighting flame whereby said circuit is closed through said flame to the burner.

4. A flame contact unit for burner control circuits comprising, in combination with a burner block having a combustion face provided with one or more gas discharge ori'es, a pilot unit for assembly in fixed relation to the burner and operative to direct a lighting flame in a predetermined path across and in contact with the combustion face of the burner, a burner control circuit connection provided with a llame contact element and adjustable supporting means including a base element in fixed relation to said pilot unit, and a refractory supporting member carried by said supporting means and removably connected with said flame contact element for suspending the latter in position projecting a material distance'across the path of the main gas flow in the same general direction as said lighting flame but farther away from the face'of the burner for bypassing the initial portion of said flame, said contact element terminating at a vpoint within the path of said lighting flame whereby said circuit is closed through said llame to the burner.

5. A composite pilot structure and flame contact unit for burner control circuits comprising a pilot unit for assembly in fixed relation to a burner block having a'front combustion face provided with one or more gas discharge orifices and operative to direct a lighting flame in a predetermined path across and in contact with the combustion face of the burner, a-burner control circuit connection provided with a flame contact element and adjustable supporting means therefor, a refractory block in fixed relation to the pilot unit and provided with a recess for housing said supporting means, and a refractory connection between said supporting means and llame Contact element and arranged to suspend the latter in position projecting a material distance across the path of the main gas iiow in the same general direction as said lighting flame but farther awal7 from the face of the-burner for bypassing the initial portion of said flame, said contact element `terminating at a point within the path of said lighting flame whereby said circuit is closed through said flame to the burner.

6. A composite pilot structure and llame contact unit for burner control circuits comprising a pilot unit for assembly in fixed relation to a burner block having a front combustion face provided with one or more gas discharge orifices and operative to direct a lighting flame in a. predetermined ascenso path across and in contact With the combustion path of the main gas flow inthe same general direction as said lighting flame but farther away from the face of the burner for bypassing the intial Portion of said name, said contact element terminating at a point within the path oi' said lighting amewhereby said relay circuit is closed through raid flame to the burner.

7. A composite pilot structure and llame contact unit for burner control circuits comprising a pilot unit adapted for assemblyat either side ofa f o burner block having a front combustion face provided with one or more gas discharge orifices for projecting a lighting flame in a path across and in contact with the adjacent portion .of the combustion face of the burner, a flame responsive control circuit connection provided with a flame contact element and adjustable supporting means therefor, a refractory block adapted for mounting on said pilot unit in either` position of the latter and in fixed relation thereto for housing said supporting means, and a refractory connection between said supporting means and flame contact element and adjustable to suspend the latter at either side of the burner with said element projecting a material distance across the properties effective for withstanding temperatures greatly in excess of 2200 F.

9. In a flame responsive circuit for controlling burner operations, the combination with a burner block having a front combustion face provided with one or more gas discharge orifices, of means for projecting a lighting flame in a predetermined path acrossand in contact with said combustion face, a circuit connection including a flame contact element and a pivotal supporting member adapted to suspend said contact element directly -in the combustion space in front of said burner orifices, said supporting member having means limiting the pivotal movement thereof for positioning the end of said flame contact element in the path of said lighting flame, said contact element and supporting member being of silicon carbide composition having refractory properties elfectlve for withstanding temperatures greatly exceeding 2200 F.

V1G. In a flame responsive circuit for controlling burner operations, the combination With a burner block having a front combustion face provided with one or more gas discharge orifices, of means for projecting a lighting llamein a predetermined path across and in contact with said combustion face, a circuit connection including a flame contact element and a refractory supporting arm of conductive material mounted for limited horizontal swinging movement, said contact element including connecting means providing restricted movement on the end of said supporting arm and directly in the path of said lighting flame.

11. In a llame responsive circuit for controlling f burner operations, the combination with a burner block having a combustion face provided with one path of the main gas flow in the same general dii rection as said lighting flame but farther away from the Vface of the burner for bypassing the initial portion of said llame, said contact element terminating at a point within the Lpath of said lighting flame whereby said relay circuitis closed through said flame to the burner.

3. In a flame responsive circuit for controlling burnel` operations, the combination with a burner block having a front combustion face provided with one or more gas discharge orilices, of means for projecting a lighting flame in a predetermined path across and in contact with said combustion face, a circuit connection provided 'with a flame contact element projecting directly through a maor more gas discharge orifices, of means for directing a lighting flame in a path transversely across and in contact with the combustion face of said burner block, and a circuit connection provided with a flame contact element also projecting a material distance across the path ofthe main gas now in the same general direction as said lighting name but farther away from the terial portion of the combustion space in front y face of the burner block for bypassing the initiai portion of said flame and terminating at a point Within the path of said lighting flame whereby said relay circuit is closed through saidfiiame to the burner, and refractory supporting means adjacent said combustion face and provided with a reversible supporting connection for said llame contact element and adapted to suspend the latter in either of two opposite angular positions for operation at either side of the burner block.

HARRY A. ATWATER.

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