US2388502A - Wall flame type burner - Google Patents

Description

Nov. 6, 1945. n R. M. SHERMAN 2,388,502v

WALL FLAME TYPE BURNER Filed Aug, 2, 1941- 2 Sheets-Sheet 2 Patented Nov. 6, 1945 WALL FLAME TYPE BURNER Rallston M. Sherman, Glastonhury,.Conn., assignor to The Silent vGlow Oil Burner Corporation, Hartford, Conn., a'corporation` of Connecticut Application August 2, 1941, Serial No. 405,233

` (c1. 15s-f4) 10 Claims.

My invention relates to oil burners of the socalled wall flame type wherein air and oil are.

discharged across a, hearth toward the wall of a combustion chamber from a centrally positioned rotary head, adjacent which wall is a so-called combustion ring for vaporizing the oil so that the vapors may mix with the air and burn adjacent said wall.

The invention, which will be best understood from the following description when read in the light of the accompanying drawings, has among its objects the provision of an improved combustion ring and associated parts, while the scope of the invention will be more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 isa Vertical section of a furnace of the above mentioned type with parts shown in elevation and parts omitted;

Fig. 2 is a plan of a segment of the improved combustion ring;

Fig. 3 is a plan of a fragment of the ring showing two segments thereof in assembled relation;

Fig. 4 is a front elevation of the fragment of the ring according to Fig. 3;

Fig. 5 is a rear elevation of the fragment of th ring according to Figs. 3 and 4;

Fig. 6 is a bottom View of the fragment of the ring according to Figs. 3, 4 and '5;

Fig. 7 is a front elevation of the left hand end portion of the ring segment according to Fig; 2 as viewed radially of said portion;

Fig. 8 is an end elevation of the segment according to Fig. 2 as Viewed from the left; and

Fig. 9 is a section on the line 9 9 of Fig. 2.

As illustrated in the drawings, supported on the base I of the furnace is the lower or waterleg section 3 of a boiler for a steam or hot water Vheating system. Also supported on the base I is a hearth plate 5 on which is positioned a hearth 'I of refractory material such as re clay. Below the hearth is a motor 9 the rapidly rotating shaft II of which carries a horizontal fan having the blades I3. Below the fan is an annular cup I5 supplied with oil through a pipe Il, the oil being discharged from the cup by centrifugal force through radially extending nozzles I9. Adjacent the wall of the combustion chamber and resting upon the upper surface of the hearth is a combustion ring formed of segments 2l. This ring at its inner side presents an oil receiving gutter 23 and above the gutter is a vertically extending wall 25 detachably carrying a series of balfles 2'I. l

With a furnace constructed as so far described,

when the burner is initially put into operation the oil from the nozzles I9 strikes the wall 25 of the combustion ring and flowing downwardly collects in the gutter 23 where it is ignited as, for example, by sparks between one or more electrodes 29 and the ring caused to occur simultaneously with the starting of the motor. The initial combustion of the oil in the gutter causes the ring to heat so that shortly the oil striking the wall 25 will be immediately vaporized, the vapors mixing with the air projected by the fan I3 across the hearth so that there results a blue flame burning against the walls of the combustion chamber. The time which elapses between starting of the motor so as to supply oil to the combustion ring and the formation of this blue flame is hereinafter referred to as the starting time of the burner and when the blue flame is formed the burner is said to have been started H'eretofore it has been proposed to employ combustion rings formed of Vfire clay or the like. It has been found, however, that such rings are oil pervious so that they initially absorb the oil striking them, with the result that free spreading of the oil on the surface of the ring does not occur and the ignition of the oil and the starting time of the burner are considerably delayed. To avoid this and other serious objections to rings of fire clay `and the like, and to secure a more durable ring, it has been proposed to employ rings made of cast iron or sheet metal which commonly have been spaced a few inches from the wall of the combustion chamber, not only because of the practical impossibility of manufacturing a ring which would exactly fit a more or less irregular and out of round surface of the combustion chamber, but to permit the flame to get behind the ring so as to cause it to heat to the highest temperature possible.

Cast iron combustion rings, it has been found, although durable, present surfaces which are more or less rough and minutely porous in respect to oil, this property of cast iron having a tendency to increase with'use on-account of oxidization which takes place. Such a surface, be-` cause of the relatively high surface tension'of the oil thereupon, tends to retard the free flow of the oil and prevent it from spreading out into a thin film necessary to promote rapid volatilization of the oil during the starting period and thereafter. In other words, cast iron, although perhaps not as porous as fire clay, has a very detrimental effect in preventing free spreading of the oil in a thin film. VWith cast iron rings it has beenV attempted to overcome this deleterious effect by causing the rings to be heated to a high temperature, but such high temperatures, it has been found, cause cracking of the oil and serious deposits of carbon.

It has also been proposed to employ combustion rings made of sheet metal, but such rings rapidly deteriorate and oxidize and prevent free flowing of the oil thereon into a thin film and besides heat to objectionably high temperatures, with the result that quick Vstarting of the burner and proper vaporization of the oil are prevented and serious deposits of carbon result.

Applicant has found that the necessary conditions to promote rapid vaporizationof theoil and the prevention of carbon deposits have notheretofore been correctly understood. He has found that to secure quick starting of the burner at least those surfaces of the combustion ring which receive the oil paradoxically should be of material of poor heat conductivity so as to reduce` the heating effect on the ring of the combustion of the oil. Such a surface portion will prevent loss of heat therefrom by conduction into the mass of the ring during the starting period, and will cause the heat to be retained at the surface of the ring so as to heat the oil. He has further found that provision should be made to have the combustion ring present an impervious surface to the oil and one which will cause the oil to have a low surface tension so that it will rapidly spread over the ring in a thin film and not be localized thereon on account of the perviousness of the ring or the character of the surface presented to the oil being such as to prevent it from spreading in a thin film. Further, by having the surface of the ring of low heat conductivity the vaporizing of the oil, which absorbs heat from the ring, acts to counteract the tendency of the ring to heat by absorbing the heat from the flame and therefore to keep the ring at a much lower temperature than rings heretofore employed, and thus prevents cracking of the oil and the deposits of carbon.

Applicant has found that the above improved results may be secured by coating the ring with vitreous enamel of low heat conductivity, and preferably enamel which is impervious and presents a permanently smooth polished surface. Such a ring may be formed` by coating the cast iron rings heretofore employed on at least the inner side thereof, that is to` say the side which faces the rotary oil distributing head, with refractory vitreous enamels of known compositions. By way of example ,.but without limitation there-l to, the following composition and enameling process may be employed. A composition is first formed consisting of 12 parts of potters clay, 8

parts of borax, parts of white lead, 2 parts of potassium nitrate, l part of calcined white mar-v ble, 2 parts of purified .potash, and 5` parts of calx of tin. After being finely powdered, mixed and fused to a vitreous mass this composition may be broken up and ground to a powder, sifted, and mixed with water to form a thin paste. The cast iron ring after being thoroughly cleaned may then have the paste applied to its surface by dipping, brushing or spraying, and the ring so coated with the paste may then be baked in an enameling oven to fuse the coating.

One form of ring according to the invention is illustrated by the accompanying drawings. Cast iron ring segments according to Figs. 2to 8 may be formed'to provide the upstanding wall 25 and gutter 23 hereinbefore referred to. Beneath the gutter each segment may be formed with a back fiange 3| and a front flange 33 both extending approximately throughout the length of the segment and being adapted to rest upon the upper surface of the hearth. As shown, at each end of the segment the space between the front wall of the gutter and the front flange 33 is closed by a wall 35 to prevent entry of oil and products of combustion beneath the ring from the siderthereof facing the rotary head of the burner.

As illustrated, one end of each segment is provided with a projecting end flange having a portion 31 at the rearward side of the wall 25 and a contiguous portion 39 at the lower edge of the Wall 35 and a further portion 4| at the rearward side of the front flange 33. The end flanges just described serve tov align the ends of adjoining segments and to close the joints between them, as clearly illustrated in Figs. 3 to 6.

Preferably the ends of the segments are so formed asl to leave rbetween them a V-shaped space l43 closed by the end flange. By so forming the segments the ring need not necessarily follow a true circle, but can be so installed as to cause it to be equally spaced throughout its circumference from the walls of the boiler section'3 forming the lateral walls of the combustion chamber. After the ring is installed these V-shaped spaces may be filled with fire clay to make, the` oil contacting surface of the gutter continuous.

As illustrated in Fig. 9, the exposed front sur'- face ofthe front flange 33 of each segment and the adjacent surfaces of the gutter 23 and upstanding wall 25 are coated throughout their entire extent with a layer of vitreous enamel 45 hereinbefore described, and also, for a reason hereinafter explained, the opposite surface of the wall 25 and rear surface of the back flange 3| likewise may be coated` with such layer of vitreous enamel throughout their entire extent.

Preferably the space between the outer surfaces of the combustion ring and the surrounding walls of thecombustion chamber presented by the boiler section` 3 are filled with a packing 4,1 which is preferably yieldable to permit expansion of the ring. Such packing material may consists of a mass of so-called rock-wool which, as its name indicates, is formed of a matted mass of slag. fibers having somewhat the appearance of wool andis agood heat insulator. It has been found, that by employing this packing, flame is prevented from getting, into the space behind the ring, with the result that the packing serves to keep the ring at a lower temperature and prevents cracking of oil in that space and deposits of carbon therein. By coating the rearward surfaces of the ring, with vitreous enamel, as hereinbefore described, the heat insulating effect of the rock-wool on the metal body of the ring is augmented, and as a result only the surface film of the enamel at the inner side of the ring is kept at a high temperature properly to vaporize the oil, that temperature being lower than were the ring at its inner side` not coated with vitreous enamel.

As illustrated', the ring segments are provided on their under sides with bosses 49. Into the boss or bosses which are opposite the electrode or electrodes 29, are tappedv rods 5| extending downwardly through the hearth to beneath the hearth plate 5, the lower ends of the rods being provided with clipsv 53 to. which a conductor may be attached for grounding the ring segment. As

'Y shown,` the electrode 29 is carried by a porcelain insulator 55 extending downwardly through the hearth to below the hearth plate 5, the electrode also being provided at its lower end with a clip 53 to which may be attached a conductor for causing the ignition spark between the electrode and the combustion ring. As the vitreous enamel with which the ring is coated is electrically an insulating material, after the enameling operation on the ring the wall 25 at its inner side is recessed, as indicated at l, by a machining operation, and in this recess is cemented, by conductive cement of any suitable character, a disk 59 of carborundum or the like to form an electrode in conductive relation to the ring segment and cooperating with the electrode 29.

It will be understood that, within the scope of the appended claims, wide deviations may be made from the forms of the invention herein described without departing from the spirit of the invention.

I claim:

1. A segment of a combustion ring for a wall llame type burner comprising a relatively thin Walled metal body shaped to form a gutter on the inner side thereof, and an upstanding wall above the outer side of the gutter, said gutter and the adjacent side of said wall having a coating of vitreous enamel of low heat conductivity.

2. A segmental combustion ring for support on the hearth of a wall flame type burner comprising segments having a part forming a gutter extending lengthwise of the segment on the inner side thereof, a front ange and back flange for supporting said part, and a flange carried at one end of the segment at the rearward side of said part for holding the latter in alignment with the adjacent end of the adjoining segment, the ends of the segments being formed to present substantially V-shaped spaces between them inwardly of the flanges at the ends of the segments when the latter are in assembled relation.

3. A burner of the wall llame type wherein air and oil are discharged toward the wall of a combustion chamber from a centrally positioned rotary head having, in combination, a hearth defining the bottom of the combustion chamber, and a combustion ring carried by said hearth adjacent the combustion chamber wall in the path of the oil discharged by said head, said ring 4being formed of relatively thin metal coated on at least its side facing said head with a layer of low heat conductivity, oil impervious, vitreous enamel having a polished outer surface.

4. A burner of the wall flame type wherein air and oil are discharged toward the wall of a combustion chamber from a centrally positioned rotary head having, in combination, a hearth defining the bottom of the combustion chamber, a combustion ring carried by said hearth adjacent the combustion chamber wall, said ring being formed of relatively thin metal presenting, at the inner side of the ring, an upper surface extending about the ring in the path of the oil discharged by said rotary head and an upwardly facing groove extending about the ring for receiving oil which drains from said surface, the latter and said groove being coated with a layer of low heat conductivity, oil impervious, vitreous enamel having a polished outer surface.

5. A burner according to claim 3 in which the combustion ring is spaced from the wall of the combustion chamber in out-of-contact relation therewith and the space between the two is filled with heat insulating material in contact with said ring for insulating the outer side of the latter and for preventing entrance of flame into said space.

6. A burner according to claim 3 in which the combustion ring is spaced from the wall of the combustion chamber and is formed of sections which are relatively movable in the plane of said ring, the space between said ring and the wall of the combustion chamber being filled with material comprising an annular resilient packing of heat insulating material in contact with said ring.

7. A burner of the wall llame type wherein air and oil are discharged toward the wall of a combustion chamber from a centrally positioned rotary head having, in combination, a hearth defining the bottom of the combustion chamber, a combustion ring carried by said hearth adjacent the combustion chamber wall in spaced relation to the latter, which ring is formed of sections relatively movable in the plane of the ring, said sections being formed of relatively thin metal presenting, at the inner side of the ring, an upper surface extending about the ring in the path of the oil discharged by said rotary head and a contiguous upwardly facing groove extending about the ring for receiving oil which drains from said surface, the latter and said groove being coated with a layer of low heat conductivity, oil impervious, vitreous enamel having a polished outer surface, and a yielding packing of heat insulating material in contact with the outer side of said ring substantially entirely lling the space between said ring and the wall of the combustion chamber.

8. A burner of the wall flame type wherein a mixture of air and oil is discharged toward the wall of a combustion chamber from a centrally positioned rotary head having, in combination, a hearth dening the bottom of the combustion chamber; a relatively thin walled metal combustion ring carried by said hearth adjacent the combustion chamber wall in spaced out-of-contact relation with the latter, which ring is formed to present, on its inner side, an upstanding oil vaporizing surface extending about the ring in the path of the mixture discharged by said head, and with a contiguous upwardly facing oil vaporiZing groove extending about the ring for receiving oil which drains from said surface; and means for insulating the outer side of said ring and substantially entirely excluding entrance of ame to the space between it and the combustion chamber wall.

9. A burner according to claim 8 in which the means for insulating the outer side of the ring and excluding entrance of flame to the space between it and the combustion chamber wall comprises a mass of heat insulating material substantially filling said space to the top of the ring.

10. A burner according to claim 8 in which the ring is formedof sections movable relative to each other in the plane of the ring, the means for insulating the outer side of the ring and excluding entrance of flame to the space between it and the combustion chamber wall comprising a mass of yieldable heat insulating material substantially lling said space to the top of the ring.

RALLSTON M. SHERMAN.

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