US2070859A - Radiant cell gas burner - Google Patents

Description

Feb. '16, 1937. A, H, DQN HQWE 2,070,859

RADIANT CELL GAS BURNER Filed Deo. l5, 1932 5 Sheets-Sheet' 1 "i jgonzjfaidfome Feb. 16, 1937. A. H; DON Howl-z 0701859 RADIANT CELL GAS BURNER Filed Dec. 15, 1952 s sheets-sheet 2 Feb. 16, 1937. A. H. DoN HowE RADIANT CELL GAS BURNER AFiled Dec. 15, 1932 A25 Sheets-Sheet 3 MMMM.

Patented Feb. 16,' 1937 UNITED STATES' :PATENT OFFICE amasseaADrAN'r cau. Gassman Alonzo H. Don Howe, Chicago, application December 15, 1932, serial No. 647,319'

.- claims.

My invention relates to gas burners. Many of its phases are especially concerned with gas burners of the surface combustion or radiant type and the use of a multiplicity of combustion cells.

Among the objects of my invention are:

(a) Conversion of a larger proportion of the heat of combustion into radiant heat, as distin` guished from Vheat to be absorbed from the combustion gases b-y the flue' passages of the boiler or lost through thestaclc As one advantage, it makes practicable the operation of my burners in boilers designed to burn coal where it was contemplated the greatest portion of the heat absorbed would be by radiation direct from the hot bed of coals. Most gas burners have operated economically only when installed in special boil-i ers having a large aggregate of iiue surfaces or a multiplicity of small water tubes calculated to extract the heat of combustion principally from contact with the hot combustion gases.

(b) Complete combustion of thegas, with a minimum of excess air on the one hand, or of carbon monoxide on the other hand. Excess air necessarily leaves the boiler at a much higher temperature than that at which it is taken in. Some of the heat of combustion must be taken to 'heat this useless excess air. The greater the proportion of excess air, the less the over-all efciency of the burner installation. In previous types of burners it has been advisable to allow more or less excess of air as a factor of safety to'insure that there will be suilcient air to support combustion without leaving carbon monoxide. By my invention, I amA enabled in practice to work with safety to more accurate proportions of gas and air.

(c) Structural compactness of the burner in relation to the amount of gas it can burn per hour, whereby the burner may be used in boilers having cramped combustion chambers. A practical difculty frequently encountered with ga's burners for heating boilers has been that more recent designs of boilers have been so compact that the' combustion chamber would not admit of the installation of a gas burner of sufficient `capacity. This problem has been aggravated by the practice of working the boiler over its rated capacity-either by inadequate initial installation or as the result of subsequently installing ad- Iditional radiation.

(d) A burner structure built up from a plural--4 ity of more or less standard units which may be increased in number to any desired capacity and which can be variously arranged to meet the (ci. 15s-104) several requirements of low, high, round, or rectangular combustion chambers, industrial furnaces (where the heat is indirected) re place burners, ete..4

(e) -IA burnerstructurally simple, sturdy, economical to manufacture, of long. life and with the elem'en'tsre'adily removable for repair or replacement-1 q While the. gas. burned in my burner will be chiefly natural or articial illuminating gasthat beinglinost prevalent-in this description the term gas",wh'en used` to indicate a combustible gas, contemplates any one of the combustible gases or combinations thereof which at normal temperatures exist in a gaseous state-such as hydrogen, carbon monoxide. methane, ethane, coal gas, natural gas, etc.and any normally liquid combustible, such as fuel oil, in a gasified, vaporized, carbureted, or similar form.

In supplying heat to boilers, furnaces, kilns, and similar heat exchange apparatus, it is generally of greater advantage to convert a large portion of the heat generated from the fuel combustion into the form of radiant heat from a suitable refractory surface. If the heat generating combustion takes place adjacent to the radiating surfaces of the refractory material it is evident that the combustion gases are not being reduced to a temperature lower than that of the material to which the heat is thus imparted, because the combustion gases are the medium from which heat is imparted to the refractory material. Similarly the combustion gases can not be reduced to a temperature lower than that `of the refractory material where the combustion gases are passed over the refractory surfaces in such `a manner as to render the material radiant at a nearly uniform temperature. In either case, if the areas of the surfaces of these refractory substances are maintained uniform and at high temperature in order to secure radiation at a high temperature, it must follow that a very consider'able portion of the potential heat contact of the gas remains inthe combustion gases and is `not available as radiant heat. If not reclaimed .be made to absorb and radiate a large portion of the sensible heat in the combustion gases.

In my solution of these problems, my invention provides for the ignition and combustion of the gas in intimate contact with incandescent surfaces of suitable refractory material and, in the course of the ow of the combustion gases from the combustion region., for absorbing and radiating the heat therein. 'Ihis absorption and radiation is progressive by increments of decreasing temperature, that is, as the combustion gases flow away from the region of combustion, they are brought successively into contact with heat receiving surfaces of the material at temperatures which progressively decrease due to the diminishing temperature of the flowing combustion gas as the result of its giving up its heat by increments to the heat receiving surfaces. By minimizing the heat conduction by the heat receiving substances, in the direction of progress or fiow of the combustion gases, the temperature of the heat receiving surfaces may be caused to decrease progressively as the temperature of the outowing combustion 'gases decreases. As a result there is a proper heat temperature gradient between the combustion gases and the heat receiving surfaces to effect a continuous-progressive heat reception to be converted into radiant heat.

In carrying out the foregoing purpose, I provide open end combustion cells in which heat extraction or radiation takes place. For the fullest benets, I confine the region of combustion to the anterior or inner end of the combustion cell, thereby leaving a considerable cell surface between its -posterlor or outer open end and the combustion region. 'I'hese surfaces beyond the combustion region are exposed to contact with gases which are not maintained at the high temperature of the combustion region, but which may progressively decrease in temperature in the course of progressive heat transfer to the cell surfaces, as above described.

For the fullest benefits of my invention I also provide, somewhat paradoxically, a slow passage of the combustion gases while at the same time maintaining a high velocity. When the gas is brought into the cell as a combustible mixture or in substantially combining portions (as distinguished from the mixing taking place in the cell from separate air and gas inlets), the combustible lmixture must enterrat a comparatively high velocity. Otherwisev the speed of flame propagation 'will exceed the velocity and cause backiiring.

ses

A high velocity is also of advantage in affording an impact or other forceful pressure of the burning and combustion gases against the walls of the recess to facilitate heat transfer and I believe also to accentuate the catalytic effect of the incandescent surface on combustion. On the other hand, the travel of the combustion gases through the cell is preferably delayed to 'afford a greater time interval for the transfer of'heat from the gases to the walls of the cell. Otherwise the combustion gases will leave the cell before asuiilcient'amount of heat has been extracted from them.

` I achieve these and other desirable results by introducing the combustible mixture into the are these: I insure that all of the surface of the cell (except perhaps lthe very innermost end) is thoroughly traversed in a systematic manner by the gases, and that most of the gases come in delayed, to further transfer to the cell wall,

but the combustion region, by a similar axial delay, can more conveniently be confined well to the inner end of the cell. This in turn leaves a greater portion of the length of the cell for combustion gases as distinguished from the burning gas, and it concentrates the combustion region near enough the end of the cell so that, if the end of the cell be of parabolic contour, the heat received by the inner end of the cell will better be reflected outwardly because the combustion region is concentrated nearer the focal point.

Another feature of my invention is the contour of the combustion cell. I find that the most effective contour is approximated by a paraboloid. Such a parabolic curve includes three portions: A cupped end portion, which, as just explained. most effectively radiates directly outwardly the heat which can be assumed as concentrated in the combustion region; an intermediate portion moderately aring which compensates for the greater volumetric expansion of the gases by combustion and which serves to increase the area of the heat transfer surfaces while confining the combustion region; and an outer region only slightly fiaring which tends to confine the rotating combustion gases against too quickly flowing out through the open end of the vcell and to prevent too much slowing up of the peripheral speed of the,y gas/es as would be the case if the end were fiared too generously.

My burner is peculiarly well adapted for radiant heaters of the type used in fireplaces because it converts so high a percentage of the heat of combustion into radiant heat and radiant heat which is in a large measure better conned in its outward direction than would be heat radiated from a planar incandescent surface. For the same reason it is peculiarly Well adapted for many industrial uses where a confined and directed radiant heat is desirable. When applied to boiler heating, the cells are preferably arranged in multiple, the assembled unit having a general contour of the boiler or furnace wall and, if desired, arranged relatively close thereto.

Preferably some 85% of the combustion takes place in the inner fourth of my cell.' 'I'he remaining 15% occurs within the cell but in progressively decreasing proportion toward the outer end, that is, with less of the 15% in the third fourth than in the second fourth and more in the third fourth lthan in the last fourth. Because practically 100% of thel combustion is within the cells, I am able to bring the ends of the cells very close to the boiler wall. I could not do this if some of the combustion were left to take place outside the cells, because the unburned gases would come in contact with the relatively cool boiler wall and be chilled below igniting temperature. This would result in the objectionable ash pit. 'I'he manifold frame 2| has a hub por-y carbon-monoxide and excess air in the discharged stack gases. I might add that even with my burner the ends of the cells should ordinarily be spaced a certain distance from the boiler wall, lest too much of the heat reected by the cell walls onto the boiler wall be re-refiected straight back into the cell. The foregoing, together with further objects,

features, and advantagesof my-invention are set forth in the following description of a specific embodiment thereof and illustrated in the accompanying drawings wherein:

Fig. 1 is a vertical section through a domestic heating boiler equipped with the burner of my invention, certain 'burner sections being removed and another partly'broken into radial section;

Fig. 2 is apartial plan view of the burner1 of Fig. 1; i

Fig. 3 is an enlarged vertical longitudinal section through one of the combustion sections;

Fig.4`4 is a transverse vertical elevation and section of a cut block taken on the line 4-4 of Fig. 3;

Fig. 5 is a horizontal longitudinal section through one of the cells taken on the line 5-5 of Fig. 4,;

Fig. 6 is a diagrammatic view of a cell block such as shown in Fig. 4 but modified to show a laminated cell construction adapted to check axial heat conduction;

Fig. 7 is a front elevationof the cell of one tier block and a fragment of another tier block, showing a modified cell structure;

Fig. 8 is a horizontal section on an enlarged scale through a cell block lembodying another modification of my invention;

Fig. 8A is a perspective of the orifice or nozzle disc;

Fig. 9` is a front elevation of a cell blockof the modification of Fig. 8;

Fig. 10 is a vertical section of a burner adapted for use in cooking stoves;

Fig. 11 is a plan View of the burner. of Fig. 10; and

Fig. 12 is a longitudinal section through another modiiied form of lcombustion cell.

Referring to Fig. 1 my burner comprises a multiplicity of cells II of generally parabolic contour. They may conveniently be formed -by juxtaposing semi-paraboloidal depressions formed in the upper and lower surfaces of a multiplicity of fire brick blocks I2 arranged in tiers I3 so that the cells are split along the horizontal planes of their axes. The inner end portion of each tier I3 of cell blocks I2 is embraced by Va cast iron jacket I4. The inner or rearward end of each jacket I4 comprises a partition wall I5 against which the ends of the blocks rest and a rear wall I6 spaced rearwardly from the partition wall to form therebetween 'an inlet manifold passage I1 for the gaseous combustible mixture. The blocks are locked and sealed to the jacket in tier formation by vertical strips I8 which may either be cement applied in plastic form or metal rods. I prefer the former. In eith'er case, the strip interlocks with opposed grooves, I9 in the lateral walls of the blocks I2, and 20 in the inner surfaces of the lateral Walls of the jacktion 23 communicating with the vertical reach of a supply pipe 24. 'I'he frame 2| includes a conical manifold passage 25 extending radially between the hub and the periphery of the frame. The jackets|4 are mounted on the frame at its periphery by hollow cap screws 26 which pass through lugs 21 on the jackets I4 and are threaded into peripherally arrangedsockets 28 on the periphery of the frame. The combustible gas mixture travels through the supplyppe 2|, the conical manifold 25, the hollow interiors of the cap screws 26, through cross ducts 29 therein and into the manifoldpassages I6 in the jackets I3.

From the jacket manifold passage I1 a, combustible mixture is distributed to a plurality of ducts 3|) in the partition I5 which on the outer side of the partition are surrounded by bosses 3|. The inner ends of the blocks are counterbored to receive these bosses. The ducts 30 in the partition register with ducts 32 in the cell blocks, which latter ducts extend parallel with the axes of the cells II. 'I'he ducts 3 2 are intersected by transverse ducts 33 which extend obliquely through the block to the interior walls of the respective cells, emerging in the cell tangentially of its surface. 'I'he cross ducts 33 are given a slight forward component relative to the axis of the associated cell. In this manner combustible mixture introduced under pressure is given a rotary movement with a forward or axial component whereby it travels a helical path along the surface of the cell.'

As-here shown, the circularly arrangedburner is setlnto the circular combustion chamber of a round boiler 34, with the top of the burner perhaps at or slightly belowthe feed door 35, depending of course on the design of the particular boiler. The boiler grates are removed, but at the grate level the combustion chamber is closed oif by a partition or diaphragm 36 which may be a layer of `asbestos on a segmental metal supporting plate. Any suitable source of combustible mixture under pressure may be fed to the supply pipe Preferably, as here illustrated, a blower 31, driven by an electric motor while the burner is .in operation, is connected through a coupling 38 (which may be a short length of rubber hose to prevent transmission of vibration from the blower and motor to the burner) to the horizontal reach of the supply pipe 24. The gas is led from a gas supply line 39 through a pressure regulating valve 40 and a mixing valve 4| where it is mixed with the air coming from the blower. The gas line 39 also feeds a pilot light 42 placed opposite the lower combustion cell of a tier of cells.

In Fig. 6 I have shown Aa modified cell structure wherein the block 43, which may contain several c ells lin tier formation, is of laminated construction. The laminations 43a, 43h, 43c, etc. are at a normal to the axis of the c'ell. They are of fire brick material. adhered together by thin layers of cement 44 such as asbestos cement. As will be more fully explained, it is a feature of my invention that the temperature of the walls of the cell decreases in successive vregions outwardly from the inner end of the cell. The material of the cell surface is primarily one having good refractory characterictics. The most satisfactory refractory materials however are not the poorest conductors of heat. To retain the temperature differentials between the various successive regions of the cell surface, it is desirable that heat conduction from one region of the cell to another be eliminated insofar as possible.

In the cell structure of Fig. 6 this is accomplished partly by the interruption in the homogeneous material of the block, and in part by the insulating effect of the non-conducting cement partitions.

In Fig. 7 I have shown another modification of the cell structure. 'Ihe block 45'may comprise a tier of several cells 46. A thin slot 41 is cut from the end of the block inwardly to communicate tangentially with the surface of the cell. 'Ihis slot extends inwardly to a point slightly outwardly of the tangential ducts 33. It is desirable to have the tangential slot 4l lead upwardly rather than downwardly, and in this case the combustible mixture should be introduced to rotate helically in a clockwise direction as seen in Fig. '7. For this reason the tangential feed ducts 33 leading into the end of the cell are arranged oppositely from the directions previously described. 'I'he action of the slot 41 is to skim off a thin layer of the outermost products of combustion as they are circulating helicallythat is, with a forward or axial componentwithin the cell. Thus those combustion gases which have been nearest the surface of the cell and have therefore transferred their heat to the block, are withdrawn by the slot 41, permitting the next layer of combustion gases to come into'direct contact with the wall of the cell and transfer its heat. If the tangential slot 41 be so arranged that all of the combustion gases are withdrawn or skimmed olf by it by the time the gases reach the end of the cell, it is possible to close off the end of the cell with a quartz window 49. Such a window may be a flat disc pressed into the end of the cell opening.

Also the space between adjacent tiers of cells,

may be closed oi into a vertical passage by strips 48 extending between ends of adjacent tier blocks. In this manner the passages formed between the tier blocks may discharge the combustion gases directly to the ues for further absorption of heat, while all of the radiant heat may be passed out principally through the windows 49 but somewhat through the end surfaces of the blocks, toward the heat absorbing surfaces toward which the cells may be directed. This complete isolation of the radiant heat from the combustion gas is of considerable advantage in certain types of industrial uses where a-high heat is desired without the chemical reactions,

soiling or other objectionable eiects, which might follow from exposure of the material being heated to the combustion gases.

In Figs. 8 and 9 I have shown a modified form of cell structure which is preferable in many respects to the specic form illustrated in Figs. 3, 4 and 5. Here the block 5D constitutes a tier of several-eight, for example-cells I. Each cell is wholly encompassed by the blo'ck, and there is no splitting of the cell wall. I'he principal feature of construction of Figs. 8 and 9, however, is the means fom` tangentially discharging the combustible mixture into the end of the cell that it may follow a helical course. The ducts 52 in the partition extend through bosses 53. In the space left around the bosses and within the lateral walls of the jacket there is packed magnesia 54 extending forwardly to the planeof the ends of the bosses 53. 'I'he cell block is set into the jacket with its rearward face against the magnesia 54. If the magnesia be in a cementitious form', it can be used to help retain the block in the jacket. In this y a fiat top gas stove.

form the end of the cell 5| is not continued to the usual cupped end of a paraboloid vbut is truncated, leaving an end opening in the block of slightly larger diameter than the discharge end of the duct 52.

Before the block is set in place, a nozzle disc 55 is either screw threaded or press-fitted into the discharge end of the duct 52. The periphery of the disc 55 is formed with teeth somewhat resembling spiral gear teeth. Preferably, however, the teeth are so formed that they run at right angles to the rear face of the disc, but at the front face of the disc are turned to an angle of only 30 to the front face of thenozzle disc. There are thus left vorices 56 between the walls of the teeth and the bore of the duct 52 which are employed as discharge ducts in lieu of the tangentially arranged ducts 33 in the form of cell structure first described. The outer face of the disc 55 is slightly convex. This is so that in general heat radiated from the incandescent surface of the cell near its inner end will on the average be reilected farther out along the cell than would be the case if the front face of the disc 55 were flat.

The convex front face of the disc 55 is preferably made a permanent reecting surface as by chromium plating it. In this way less heat will be absorbed by the disc and conducted along the'boss 53 with the attendant danger of preignition to the combustible mixture in the jacket manifold. The .body of magnesium 544 also, by its insulating value, `forms a stop against the conduction of heat from the rearward end of thev cell block to the jacket. It will also be observed that the cross 'section of the boss 53 is such as readily to conduct any heat absorbed by the boss out and dissipate it over the large area of the jacket. In providing the reflecting surface on the disc, the magnesium insulation 54, and the heat conduction for the boss 53, I provide against dangers of pre-ignition or destruction of the nozzle parts after the cooling flow of the incoming combustible mixture has stopped and the cell walls have been left in incandescent state.

The nozzle disc 55 may be rendered more easily -ets are arranged in annular formation about a circular frame. In the instance of a square or rectangular boiler, the jackets may be arranged on a square or' rectangular frame, so that the burner as a whole will be block-shaped. In those instances where the combustion chamber of a boiler is unusually low, the jackets may be arranged so thatA the cells face upwardly. Similarly, in the instance of a fireplace, the jackets :my be arranged on a straight frame so that all of the cells are parallel. The advantages of my burner structure may also be applied to the instance of gas cooking stoves, and especially. in ovens or open burners used in restaurants, hotels, bakeries, etc. l

In Figs. and-11 I have illustrated a form of burner unit which would be peculiarly suitable to Here a generally flat horizontal frame 60 having an upstanding marginal rim 6I carries manifold passages embodied in its bottom side, which lead to a plurality of ducts 52 extending through bosses 53, and discharge through nozzle discs 55. For a large burner there lremovable forrepair, cleaning or repolishing by may be five cells to such a unit. A block 63 containing ve cells, each of which registers with one of the ducts 52, is dropped into the frame and positioned by its rim 6I. In this case the block may be said to contain cells in a plurality of tiers. The assembled frame and block 63 it will be understood is mounted beneath the grill top of a gas stove where the usual burner would other- Wise be. l

In Fig. 12 I have shown somewhat diagrammatically a further modification of the cell structure of the type of Fig.8. This form is particularly suited to industrial uses such as ht ltreatment where the temperatures run much higher than in the ordinary boiler. With such high temperatures two phases of my burner must be given particular consideration. One is the deleterious effect of the high temperature at the inner or combustion end of the cell on the refractory material constituting the lsurface of the combustion end of the cell. The other is the danger of heating the manifold jacket to a temperature where the combustible mixture will ignite in the manifold.

As to the rst of these problems-the ability of the surfaces -of the inner end of the cell to stand up under the heat-the problem is somewhat alleviated by the use'v of a multiplicity ofv peripheral orices of the form .of Fig. 8. In the form of Fig. 5, having only two orifices there is a tendency to develop an extremely high localized temperature at two spots on the cell wall. The multiplicityof orifices in Fig. 8 distributes these spots so that they do not become apparent under ordinary temperature conditions. However for the very high temperatures involved in industrial uses I may line the'cell, or preferably only the inner end of the cell as-shwn`in Fig. 12, with a thin layer 65 of a refractory material which is harder and denser than the body of the cell block and which has a higher fusing point whereby it can withstand higher temperatures. Such a lining may be applied as a paste or cement'made from either carborundum or fire brick material of the characteristics just stated. To make the entire cell block of such material of high density would not be desirable because refractory material in general hasa heat conducting characteristic roughly proportional to its density. As will be more fully explained, a low heat conductivity factor for the cell block in so far as possible is desirable.

The main body of the cell block of Fig. 12 as well as that of the other forms of cell illustrated is preferably a refractory material having a relatively high fusing point` but one having a low heat conductivity characteristic and that, for most fire brick material, means la. low specific gravity. For example, the ordinary iirebrick (2t/4" x 41/2" x 9") weighs seven pounds, whereas a brick of that size of the refractory material I would use for my cells would weigh say only two and seventy-five hundredths pounds. The composition of the refractory material may conform to the usual fire brick content of aluminum oxide, sodium silicate and magnesium oxide and their more complicated combinations. Whether the cells be split as in Fig. 3 or not split las in Figs. 8 and 12 depends to some extent on whether the refractory material selected is one which will withstand the internal stresses of the high. temperatures without cracking. A slbt as described in connection with Fig. '7 would have the incidental advantage of preventing cracking.

As to the second phase of the problems occasioned by excessive temperature installationsthe danger of combustion within the manifold-.

I have incorporated in Fig. 12 separate gas and air orifices whereby the gas and air are admitted separately and unite within the cell, as distinguished from the gas and air passing into the cell as a pre-mixed combustible mixture. Here the primary jacket manifold I1' would conduct only air through the peripheral orifices 56 of the orifice plug or disc. But that air would be preheated just asa combustible mixture is preheated by the vj acket manifold in the other forms shown. The gas in the form of Fig. 12 is introduced by way ofa secondary manifold 66 which maybeincorporated in the jacket casting. Ax-

ially aligned with each cell there is-a gas feed tube 61 threaded at one end into the common wall for the primary and secondary manifolds. so'as to communicate with the interior of the secondary orgas manifold 66. After the tube 61 is screwed into place, the orifice plugis set in place, it having a socket 6B to receive the other inner end of the cell. Inasmuch as a cubic footy of ordinary or illuminating gas requires eight cubic feet of air for its complete combustion, a single central gas orifice with a plurality of air orifices of similar size around it works out quite satisfactorily. The gas it is true is not introduced with a swirling motion, but inasmuch as some eight-ninths of the combustible mixture is introduced tangentially and given the swirlingA motion, the fact that the gas is not also tangentially introduced is relatively immaterial; A further feature of this method of separately vintroducing the gas at the vortex of a virtual vwhirlpool isvthat `it may be to a certain extent sucked Ainto the' cell thereby offsetting the dii.'- culties often'e'ncountered by low gas pressures especially during peakA load periods. It permits the setting of the gas pressure reducing valve at a lower maintained pressure than when the gas feed has to be wholly by positive pressure.

IV shall now discuss in greater detail the operation of the burners whose structure I have described. As I believe the specific cell structure illustrated in Figs. 8 and 9 is preferable for most purposes, I shall describe the operation of the cell in connection with that specific embodiment. The operation of the other modification is so similar as notl to require separate discussion.

`The orifices afforded by the passages 56 in thenozzle disc 55 discharge the combustible mixture of gas and air into the inner end of the cell at substantially a tangent to the surface of the cell and with a slow forward or axial component. As previously explained the velocity of the incoming mixture must be fairly high in order to prevent backring. In` its rotary or whirling movement the mixture describes a generally helical path outwardly along the surface of the cell as indicated by the arrows in Fig. 8. The lead of the helix however is relatively small, so that there is a very long peripheral travel in relation to the axial travel. i i l Actual combustion is largely confined to the inner end of the cell, so that the surfaces of the inner end of the cell become incandescent, that incandescence further aids the concentration of combustion at the inner end of the cell, partly due to the heat to which the combustible mixture is subjected by the incandescent surfaces and the combustion itself and partly by the catalytic action of the incandescent surfaces. The parabolic contour of the cell with its progressively increasing diameter but decreasing rate of vprogressive increase has these advantages: (a) The heating of the combustible mixture by its combustion greatly increases its volume, and initially rather rapid increase in the diameter of the cell as the combustion takes place allows for this expansion of the gas without generating such a pressure as would either shoot the ame out of the cell or would cause a back pressure interfering with the rate of feed of the combustible mixture through the orifices. (b) Because the swirling gases as an incident to their centrifugal force constantly seek a larger radius, the gradually increasing diameter of the cell maintains and controls to a large extent the axial component'of the movement. (c) The incandescent surfaces at the narrowed inner end are placed opposite the open end of the cell and may radiate heat directly out through the open end of the cell. (d) The smaller space or volume at the inner end of the cell in which combustion takes place brings the combustion at a region of more concentrated incandescence of the cell surfaces whereby the combustion is accelerated both by the concentrated heat to which the combustion gases are subjected and to the greater catalytic effect due to the higher incandescence of the adjacent surfaces. (e) 'I'he latter, in turn, facilitates holding the combustion in the inner end of the cell where the heat absorbed by the surfaces may best be radiated out through the open end. (f) 'I'he lesser rate of increase of the diameter toward the outer or open end of the cell maintains the peripheral speed which would be lost by a continued rapid increase in the diameter and the maintained peripheral speed in sures a component or radial pressure of the products of the combustion against the surfaces of the cell so that heat transfer is accelerated. (g) 'I'he lesser rate of increase of diameter toward the outer end delays the axial movement. whereby the products of combustion may be held in the cell for a longer time and until they have given up all of the heat which is to be extracted for radiation. In) While I have mentioned that the incandescent surfaces and ,especially those toward the rear end of the cell which would be visible from a front elevation of the cell radiate heat directly outwardly through the openend of the cell, a large proportion of heat from the` incandescent surfaces is radiated out the end of the cell indirectly. That is, from a point on the incandescent surface toward thev inner end of the cell, heat will be reflected toward the opposite side but somewhat forwardly and again to the first side but further forward, and so on in a crisscross but generally forward path. The parabolic contour of the cell surfaces better insures that in general at each succeeding stretch of such crisscross radiation the reected heat will be given a greater forward movement.

After the burning mixture'of gas and air has passed over a small area-which may be designated as zone A,of the cell surfaces, a certain portion-Qr--of the potential heat content of the gas has been absorbed and radiated or otherwise dispersed into the surrounding medium. This heat quantity Q1 corresponds to a reduction in the temperature of the products of combustion by an increment t-ti. The gases next pass over another small areaP-zone B-of the cell surfaces. Zone B is also free to radiate and otherwise disperse the heat absorbed until a state of equilibrium is reached. Due to the lower temperature of the products of combustion entering zone B the surfaces of this zone cannot attain as high a temperature as that of the preceding zone A although the heat gradient between the temperature of the gases and the cell surfaces may remain approximately the same. In zone B there is another increment of heat, Qi, absorbed and a corresponding reduction of the temperature of the products of combustion, ti-tz.

In like manner each succeeding zone, C, D, E, etc. absorbs and radiates a small increment of heat Q3, Q4, Qs, etc. which is accompanied by a reduction of the temperature of the products of combustion by small increments tz-ta, tzr-t4, tir-t5 and the temperature attained by the surfaces of each zone is also less than that of the preceding zone by approximately equal increments. The value for the summation Q of Q1, Q2, Q3, Qn is equal to the specific heat content of the products of combustion between the theoretical flame temperature t of the gas-air mixture and the final temperature tn of the gases leaving the cells. If suitable means are provided for continuing the path of the products of combustion over surfaces free to radiate the heat they absorb, the summation value Q will represent a large portion of the -potential heat content of the gas.

From calculations based uponempirical formulae which I have derived from experimentation together with data known to those familiar with the art, I believe that the most satisfactory result is obtained when the shape of the cells is that which would be secured by revolving about its y axis a parabola of the form y=b, with positive values for For conditions where the medium to which heat is to be imparted is at a comparatively low temperature, such as would he the case in a low pressure boiler or domestic hot air heater, a value of 3 may be given to n, and b may be taken at unity. When the medium is to be raised to a higher temperature, as is the case in certain industrial applications, a de' creasingly smaller value should be given both n and b. Thus for varying conditions of application a high eillciency may be obtained by giving suitable values to b and n in the equation set f orth. In using the parabolic formula for the form of the combustion cell, the orifices 56 should preferably-be located on orfV near the periphery of the annular cross-section passing through'the focus.

It will thus be seen from the foregoing discussions that the heat of the combustion gases is progressively extracted. They are discharged from the open ends of the cell at a relatively low temperature, leaving but a minor portion of the total heat still to be extracted by boiler iiues, economizers or the like. If the heat were not thus progressively extracted, the radiation from the surfaces would result in the emerging products of combustion being at a temperature almost as high as that of the hottest surfaces of the cell. The discharged gases would be of relatively high temperature, leaving a large portion of the total heat to be absorbediby the boiler iiues rather air. The mixing valve accurately proportions the meansfor' holding the blocks in assembled relagas and air. Once this accurately proportioned mixture passes through the orifice into the cell, it is retained in the incandescent catalyst environment of the cell until all the air land gas have an opportunity ofunitin'g. There'is no danger of the air and gas passing out of the cell Without complete combustion.

I claim: t

1. A gas burner comprising combustionlcells.

arranged in multiple, each cell formed from a structure of refractory material andV being of elongatedshape with a narrowing closed inner end and with increasing diametertowardl the outer end, and a nozzle structure centrally disposed at the inner end of the cell, the nozzle comprising annularly arranged orifices discharging substantially tangentially into the inner end y of the cell, and manifold means for supplying a gaseous combustible mixture to each of the nozzle structures.l I

2. A gas burner comprising a block of refractory material, an' elongated combustion cell therein, open at its-forward end,..a supporting jacket embracing the rearward end of the block, the jacket including a manifold passage, a duct leadingthrough the jacket from `the manifold to the cell for a gaseous combustible mixture to be burned in the cell, the walls of the cellin operation being heated to incandescence, and a body of insulating material of less heat conductivity than the block between the rear end of the block and the jacket and surrounding the duct.

3. A combustion cell for a gas burner comprising a block of refractory material having an elongated combustion recess therein of generally paraboloidal contour with its larger end opening at one'end of the block and the inner end within the block, and an orifice duct in the refractory material of the block directed and discharging tangentiallyinto the inner end of the recess.

4. A gas burner comprising a plurality of blocks of refractory material in juxtaposed relation, the mating sides of the blocks having registering recesses, each recess being of generally semi-paraboloidal form opening at one end, and

tion to provide a battery ofv combustion cells.

5. A gas burner comprising a frame constituting a manifold passage, a plurality of manifold jackets supported side by side on the frame, each jacket constituting a sub-manifold passage communicating with the manifold passage, one or more blocks of refractory material mounted in each jacket with one end thereof embraced by the jacket, each block forming at least one,v and the blocks in each jacket containing a plurality of', elongated combustion cells having open ends away from the jacket, and orifice ductsleading from the sub-manifold to the inner end of each cell. A 6. A gas burner Acomprising an annular frame, jackets annularly disposed about and mounted on the frame, a block of refractory material carried in .each jacket and extending radially therefrom, a tier of combustion cells formed in each jacketed block, each cell having an open end at the outer end of the block and all of the cells being arranged substantis`ly radially, and manifold passage means for conducting a gaseous combustible mixture to the inner end of each cell, the combustion being confined to the interior of the cells and heating their interior surat its outer end and of circular cross-section' of Aincreasing diameter toward the outer end, and

means atV the closed narrow inner end forming a tangentially directed orice admitting a com- 'faces to incandescence forradiation outwardly bustible gaseous mixture'substantially' tangentially of the cell at its inner end, andmeans for supplying the mixture through the orifice under velocity whereby the major portion of the mixvture is thrown against the wall of the cell and that the combustion takes place substantially wholly Within the cell and at its wall, with conibustion starting adjacent the orifice and in the portion of narrowing diameter.

8. A gas burner comprising a structure forming-an elongated combustion cell with surfaces of refractory material, the cell being narrowed toward, and closed at, its inner end and of increasing diameter toward the other end, the other end being open, and tangentially directed orifice means at the inner end, and means for supplying gas and air to the orifice means under pressure whereby the gas and air describe a helix along the wall of the cell and combustion takes place substantially wholly within the cell starting adjacent its inner end. v

9.. A gas burner comprising a structure forming an elongated combustion cell with surfaces of refractory material, the cell being narrowed to. ward, and closed at, its inner end and of increasing diameter toward the other end, the other end being open, and tangentially directed orifice means at the inner end, and means for supplying gas and air to the orifice means under such pressure that the gas and air describe a helix along the wall of the cell and combustion takes place substantially wholly within the narrowed end of the cell whereby the surfaces of the cell toward the outer end are contacted only by the gaseous products of combustion.

10. A gas burner comprising a combustion cell structure havingwalls of a refractory material, the cell being of substantially paraboloidal contour with an open outer end and a closed inner end and means forming a tangentially directed orice for introducing a gaseous combustible mixture into the cell in a generally tangential direction at a region substantially in a plane at a normal to the axis of the paraboloid at its focus, and means vfor supplying the mixture tothe orice under pressure whereby combustion occurs substantially wholly toward the inner end of the cell with the-mixture and its products of combustion continuing ahelical movement tothe outer end of the cell.

l1. A combustion cell comprising a body of refractory material having an elongated cell formed therein narrowing toward its inner end, -and an orifice nozzle at the inner end of the cell comprising a central fluid fuel orifice and peripherally arranged air orifices thereabout, the air orifices extending tangentially into the cell to Whirl in a helical path therein and draw the gas into the Whirl, and means for supplying air to the orifices under pressure whereby the resulting mixture burns chiefly within the narrowed end of the cell.

12. A uid fuel burner comprising a structure forming a combustion cell of heat resisting material, the sell being circular in cross section and elongated Ain axial section, opening at its outer end, and of ensmalling diameter along the curved contour toward a closed inner end, air fy orice means for tangentially directing air at the inner end of the cell, fuel orifice means for introducing fluid fuel for mixture with the air discharged through the air orifice means, and means for supplying air to the air orifice means under pressure whereby the air together with the fluid fuel mixed therewith (and subsequently the gaseous products of their combustion) describes a helix along the contoured wall of the cell and to the open end thereof and combustion takes place chiey within the cell, starting adjacent its inner end.

13. A gas burner comprising a Abody of heat resisting and insulating material providing a refractory walled cell circular in transverse section and elongated in axial section, open at its outer end and of ensmalling diameter along a curved contour toward a closed inner end, a metal wall spaced inwardly from the inner end of Athe cell and extending across and defining the inner side of the body, a tube disposed axially of the cell and extended from the metal wall substantially to the closed inner end of the cell, a plug set into the end of the tube at the closed end of the cell and having peripheral slots cooperating with the tube to form orices for directing gaseous mixture into the inner end of the cell tangentially thereof to whirl in a helical path along the contoured wall thereof and to the open end thereof, and means for supplying a. combustible mixture of gas and air to said tube under pressure whereby the combustion thereof takes place chiefly within the cell and starting adjacent the inner end of the cell.

14. A gas burner comprising a block of refractory material forming a cell circular in transverse section and elongated in axial section, open at its outer end and of ensmalling diameter along a curved contour toward a lclosed inner end, a metal wall spaced inwardly from the inner end of the cell and from the inner side of the block and disposed more or less at a normal to thel axis of the cell, a tube disposed axially of the cell and extending from the metal wall substantially to the closed inner end of the cell, an orifice device at the end of the tube at the closed end of the cell for directing gaseous mixture into the end of the cell tangentially thereof to whirl in a helical path along the contoured wall thereof and to the open end thereof, means for supplying a combustible mixture of gas and air to said tube under pressure whereby the combustion takes place chiefly within the cell and starting adjacent the inner end of the cell, and a body of heat resisting insulating material disposed between the inner end of the block and said wall and surrounding the tube.

15. A gas burner comprising a block of refractory material forming a cell circular in transverse section and elongated in axial section, open at its outer end and of ensmalling diameter along a curved contour toward a closed inner end, a ring-like member coaxial with the cell disposed inwardly of the closed end of the cell, a. plug set in the ring member and having obliquely a1'- ranged peripheral slots cooperating with the ring member to form orifices for directing a gaseous mixture into the inner end of the cell tangentially thereof to whirl in a helical path along the contoured wall thereof and to the open end thereof, and means for supplying a combustible mixture of gas and air to the innerside of said oriices under pressure whereby the combustion thereof takes place chiey within the cell and starting adjacent the inner end of the cell.

ALONZO H. DON HOWE.-

Images