US3179157A - Deep combustion radiant surface gas burner - Google Patents

Description

April 20, 1965 M. PARTIOT 3,179,157

DEEP COMBUSTION RADIANT SURFACE GAS BURNER Filed NOV- 28, 1962 mg WWW INVENIOR Maurice Parfiof BY 17M, 44mm),

ATTORNEY S United States Patent 0 3,179,157 DEEP COMBUSTION RADIANT SURFACE GAS BURNER Maurice Partiot, 12 Rue du Plateau Saint Antoine, Le Chesnay, France Filed Nov. 28, 1962, Ser. No. 240,704 10 Claims. (Cl. 158-116) This application is a continuation-in-part of my co pending application Serial No. 36,767, filed June 17, 1960. for Deep Combustion Radiant Surfaces With Special Blotting.

The invention concerns radiant ceramic blocks and in particular the arrangement of passages thcrethrough for conducting the gas mixture.

It has been proposed in the past to burn the air and gas mixture at the surface of a ceramic block of low heat conductivity, so that when the said block heats up it becomes emissive of heat radiation as the combustion penetrates to a depth of about one millimeter inside the passages or perforations made in the block to 'supply combustible mixture to the radiant surfaces.

Examples of such block are to be found in the British patent to McCourt, No. 6,312 of 1915, in which cylindrical passages are perforated through a porous refractory medium containing air cells such as has been well known in the refractory art for more than a century. In the British patent to Wilson, No. 25,714 of 1912, is disclosed a perforated slab or disc of convenient size or shape, made from fire clay, asbestos, or fire clay and asbestos substance or other suitable non-conducting refractory material. Later disclosures such as Schwank, US. Patent No. 2.775.294, recite anew the techniques and limitations disclosed in the above patent as well as described in the prior art.

The Wilson design shows a cavity or retort pattern in which a cylindrical passage is cut squarely across the bottom surface of the cavity, and a plurality of cavities is distributed evenly over the surface of the radiant block. When one attempts to construct the Wilson slab it is found that the square distribution and shape of the cavities and the wall strength required between cavities limits the aggregate area of the through passages to about twelve or fifteen percent of the total radiant outside superficies ofthe outside slab.

It is an object of the present invention to provide a pattern of holes or cavities which .allow as much as forty percent or more of aggregate passage area while retaining adequate mechanical resistance, a greater exchange surface for the combustion gases to be in contact with the ceramic, and a greater angle of dispersion over an area of ceramic material from which heat can be radiated to outer space.

To that effect. I provide one or more of the following features:

(1) A hexagonal distribution of the passages in honeycomb style, so as to crowd the said passages into the minimum area.

(2) A repeated cavity pattern regularly distributed over all the slab, each cavity arrangement receiving gas flow from a plurality to as many as eight adjacent passages.

(3) A slot connecting the outer end of the passages and cutting the passages at an acute angle to their axes.

(4) A number of fins F within each cavity formed by the walls separating two adjacent passages, so as to provide in a single manufacturing operation the maximum heat exchange surface.

(5) A slot construction which cuts through the wall separating two rows of passages and which may be positioned to cut only one single row of passages.

(6) In a preferred embodiment of my inventionI also provide an asymmetrical exhaust port for gas flow during combustion which causes the flame coming out of one passage to strike the fin placed just at the opposite side of the cavity.

(7) By providing a cavity design involving more than one row of passages, the outer intact or uncut end parts of the through passages are caused to radiate at a very high rate. This radiant heat exchange upgrades the temperature and intensity because of reverberation or mutual reflection of each side of. the cavity to the other. The radiation level is built up within the said cavity before radiation to the outer space takes place.

(8) The effect of variation of gas pressure on the radiant cfliciency of my device is less critical because the gas flame, regardless of its length or intensityyrcmains in contact with at least one substantial part of the fins F or of the passage wall surface.

(9) The lozenge, triangular or trapezoidal form of the cavity was chosen for tooling purposes, and the asymmetrical pattern of gas flow during discharge from sa d passages into the said cavities causes a whirling sweeping motion of the gas within each of the cavities which increases the heat interchange between the burnt gases and the ceramic fins or walls.

The cavities may or may not be joined to each other by their slots, and my invention is not intended to be limited to isolated cavities as shown in the preferred embodiment. The ceramic material comprising the block or slab is constructed of clay to which may be added materials having higher insulating properties than the clay itself, for retarding heat flow within the cavity or the block. Also. the structural strength of the block may be increased by suitable binders such as heat rcsistant plastics and silicone compounds to prevent the walls between cavities from disintegrating after repeated heating and cooling cycles resulting from use. An equivalent result is obtained by using block material with a low relative cocflicient of expansion and materials in the block mix which have substantially the same or closely related coefficients of expansion.

Referring to the drawings:

FIGURE 1 shows a fragmentary plan view of a corner of a radiant slab within a perimeter of about ten millimeters, and the detail design of one retort or cavity surrounded by a repeat pattern of the detail design.

FIGURE 2 shows a section through the first cavity of FIGURE 1.

FIGURE l, which is a view of the upper, radiant surface of a ceramic slab-type grid of my invention, shows one possible arrangement of. the cavities and passages in accordance with the present invention. In the particular arrangement shown, four passages open into each cavity, but it will be understood that it is within the scope of this invention to have a greater or smaller number of passages open into each cavity. FIGURE 1 further illustrates a preferred arrangement of the passages associated with any cavity; more specifically, considering the plurality of passages P1-P4 which open into cavity CI, it will be noted that the centers of any combination of three mutually contiguous passages within a cavity lie at the respective vertiees of a substantially equilateral triangle. This feature of the invention may readily be brought about by so disposing the longitudinally aligned passages of one row of passages so as to be offset or staggered with respect to those of the adjacent row. Thus. the passages P15, P16, P3 and P4 are so offset longitudinally relative to the adjacent row of pass-ages P13, PM, P] and P2, that each passage P15, for example, of the one longitudinal row lies substantially opposite the midpoint of the segment joining the adjacent passages P13 and P14 in the adjacent row. Passage P14 is, accordingly, similarly disposed relative to the adjacent passages P15 and P16. This arrangement makes it possible to maximize the cumulative port area of the passages opening into any cavity relative to the total area of the cavity.

In the disclosed embodiment of FIGURES 1 and 2, it can further be noted that the staggered or offset relationship between adjacent longitudinal rows of passages exists as well between a longitudinal row of passages associated with one group of cavities and an adjacent longitudinal-row associated with another group of cavitics. Thus, the relationship previously described exists as well between the row of passages comprising passages P13, P14, P1 and P2. on the one hand, and the adjacent row of passages comiprising passages P7, P8, P11 and P12. Such an arrangement of the passages over the surface of the block makes it possible to maximize the cumulative port area of the entire block relative to the total area of such block. Of course, it is also within the scope of the invention to have a smaller spacing amongst the passages associated with any one particular cavity as compared to the spacing between adjacent passages respectively associated with different cavities.

With respect to the passages associated with any one cavity, FIGURES l and 2 show that at least a part of the wall defining those passages lying at the periphery of the cavity extends upwardly toward the top of the grids radiant surface. However, a portion of the passage-defining wall of such cavities is, in effect, cut away or removed, as by the die which may be used to form the cavities, and the cut-away portion is generally that which faces the cavities interior portion. In the particular arrangement shown in FIGURE 1, where, as previously noted, the three mutually contiguous passages of any one cavity have their centers lying substantially on the vertices of a substantially equilateral triangle, it may be seen that the depressed portion of the cavity generally corresponds to the area lying within the confines of the thus-defined triangles.

In the illustrated embodiment of FIGURES l and 2, the peripheral citcd walls of each cavity slope upwardly and outwardly from the bottom of the cavity, but it is of course within the scope of the invention to have the cited walls extend upwardly and parallel to the axis of the passages.

In FIGURE 2 is shown the preferred design of the slab with the intake or cold face of the slab at the bottom. The gas mixture at 105% to 125% of air as compared to the ideal 100% air figure for theoretically perfect gas combustion, is fed by any of the usual methods into passages P. The gas ignites in the shaded zone BB. As ndicated, zone BB experiences variation in depth and ength in accordance with the gas feed pressure. The lot gases expand during combustion and are deflected iidewise, more particularly against fin F, and when the :as pressure increases, the deflection velocity and impact in said fin increases as a function of the pressure. In he prior art McCourt and Schwank designs, the gas cOmustion flame has a tendency when pressure increases, 3 burn outside the fiat plate, well above its radiant level, nd the heat therefrom is lost by convection.

In the cavity design of FIGURE 2, which provides for dewise deflection of the heat gases, the efficiency of the idiant heat output as compared to the heat input measred by the gas consumption is high and remains high ver a wide range of gas pressure levels. As a result, to fins F and the wall passages facing the fins radiate :at to each other and to the outer space at a vastly )graded level. While there have been described above what are presttly believed to be the preferred forms of the invention, .riations thereof will be obvious to those skilled in the t and all such changes and variations which fall within e spirit of the invention are intended to be covered by the generic terms in the appended claims, which are variably worded to that end.

I claim:

1. A radiant grid element constructed to conduct a combustible gas mixture to a surface thereof and comprising, a unitary block of refractory material having a myriad of minute-bore substantially straight elongated passages extending therethrough from a first boundary surface of said block toward a second boundary surface thereof 'for conducting from said first surface a myriad of streams of a combustible gas mixture toward said sec ond surface for combustion adjacent said second surface, said block at said second boundary surface having therein a plurality of cavities into each of which a plurality of said passages open, each said cavity being defined in part by a substantially surrounding and substantially continu- Ous upstanding wall portion and in part by a bottom areal surface depressed below the level of said second boundary surface, said upstanding wall portion intersecting at least some of said passages which open into the respective cavity defined by said wall portion and at an acute angle to the axis of said intersected passages to form an escape means which passes a part of the gas mixture flowing through each intersected passage at an angle away from its axis and toward the central portion of said cavity, at least one of said passages opening at least in part into said bottom surface of each said cavity.

2. The radiant grid element of claim 1 wherein said upstanding wall portion intersects at least some of the intersected passages adjacent the axes of such passages to form a plurality of relatively thin-walled fins between successive of such passages, which fins become readily radiant as a result of the action of said escape means in diverting a part of said gas mixture toward the central part of said cavity, whereby each said cavity provides an increased highly radiant surface below the level of said second boundary surface.

3. The radiant grid element as defined in claim 1 wherein at least some of said intersected passages communicate with the interior of said cavity at substantially the bottommost depressed portion of the cavity but also have side wall portions which extend to said second boundary surface.

4. The radiant grid element of claim 1 wherein each said cavity has at least three passages which open thereinto and are intersected by said upwardly extending surface, each group of three said passages which are mutually contiguous having their centers disposed substantially at the respective vertices of an equilateral triangle, said interior portion of each said cavity lying substantially within the confines of the said respective equilateral triangle so defined.

5. A radiant grid element constructed to conduct a combustible gas mixture to a surface thereof and oomprising, a unitary block of refractory material having a myriad of minute-bore substantially straight elongated passages extending therethrough from a first boundary surface thereof toward a second boundary surface thereof for conducting from said first surface a myriad of streams of a combustible gas mixture toward said second surface for combustion adjacent said second surface, each group of three said passages which are mutually contiguous being also mutually substantially equidistant from each'other, said block at said second boundary surface defining therein a plurality of indentations each defined in part by a central areal depression and in part by a peripheral surface substantially surrounding said depression and extending from said depression upwardly to said second boundary surface, a plurality of said passages opening into each said indentation and with at least some of said plurality of passages terminating at least in part at said peripheral surface to thereby provide a slanted opening for such passages forming an acute angle with their axes so as to discharge at least a portion of said combustible gas toward the central portion of said indentation.

6. A radiant grid element constructed to conduct a c0mbustible gas mixture to a surface thereof and comprising, a unitary block of refractory material having a myriad of minute-bore substantially elongated passages extending therethrough from a first boundary surface thereof toward a second boundary surface thereof for conducting from said first surface a myriad of streams of a combustible gas mixture toward said second surface for combustion adjacent said second surface, each group of three said passages which are mutually contiguous being also mutually substantially equidistant from each other, said block at said second boundary surface having therein a plurality of discrete indentations spaced at substantially regular intewals and each defined in part by a central areal depression and in part by a peripheral surface substantially surrounding said depression and extending from said depression upwardly to said second boundary surface, and a plurality of said passages opening into each said indentation, some of said passages opening at least in part into said peripheral surface and some of said passages opening at least in part into said central depression.

7. The radiant grid element of claim 6 in which said peripheral surface completely surrounds said depression.

8. The radiant grid element of claim 6 in which all said passages are of circular cross-section and have the same diameter.

9. A radiant grid element constructed to conduct a combustible gas mixture to a surface thereof and comprising, a unitary block of refractory material having a myriad of minute-bore substantially straight elongated passages extending therethrough from a first boundary surface of said block toward a second boundary surface thereof for conducting from said first surface a myriad 3 of streams of a combustible gas mixture toward said second surface for combustion adjacent said second surface, said block at said second surface being defined in part by a plurality of discrete first areal surfaces extending in any direction only a small portion of the distance across said block and a plurality of discrete second areal surfaces, said first and second areal surfaces being respectively at different distances from said first surface of said block, said second surface being further defined by sloping surfaces which join said first and second areal surfaces, a plurality of said passages opening at least in part into said slanted surfaces to provide thereby slanted discharge openings for such passages each of which forms an acute angle with the axis of the respective passage and causing at least a portion of the combustible gas mixture flowing through such passages to be directed toward the adjacent depressed areal surface, some of said passages opening at least in part into those of said first and second areal surfaces which are nearest said first boundary surface.

10. The radiant grid element of claim 9 in which said discrete first areas are closer to said first boundary surface of said block than are said second discrete areas to form thereby a plurality of cavities in said. second boundary surface, each said passage opening into one of said sloping surfaces directing a portion of the combustible gas mixture entering such passage toward the interior of the cavity which is contiguous to said sloping surface.

References Cited by the Examiner UNITED STATES PATENTS 1,074,626 10/ 13 Kemp et al. 1,223,308 4/17 Bone et al. 158-99 1,731,053 10/29 Lowe 158--99 1,901,086 3/33 Cox 158-99 X 2,533,143 12/50 Scharbau et al. 2,775,294 12/56 Schwank 158--116 FOREIGN PATENTS 558,007 6/57 Belgium. 601,249 1/60 Italy.

JAMES W. WESTHAVER, Primary Examiner.

Claims (1)

1. 9. A RADIANT GRID ELEMENT CONSTRUCTED TO CONDUCT A COMBUSTIBLE GAS MIXTURE TO A SURFACE THEREOF AND COMPRISING, A UNITAYR BLOCK OF REFRACTORY MATERIAL HAVING A MYRIAD OF MINUTE-BORE SUBSTANTIALLY STRAIGHT ELONGATED PASSAGES EXTENDING THERETHROUGH FROM A FIRST BOUNDARY SURFACE OF SAID BLOCK TOWARD A SECOND BOUNDARY SURFACE THEREOF FOR CONDUCTING FROM SAID FIRST SURFACE A MYRIAD OF STREAM OF A COMBUSTIBLE GAS MIXTURE TOWARD SAID SECOND SURFACE FOR COMBUSTION ADJACENT SAID SECOND SURFACE, SAID BLOCK AT SAID SECOND SURFACE BEING DEFINED IN PART BY A PLURALITY OF DISCRETE FIRST AREAL SURFACE EXTENDING IN ANY DIRECTION ONLY A SMALL PORTION OF THE DISTANCE ACROSS SAID BLOCK AND A PLURALITY OF DISCRETE SECOND AREAL SURFACES, SAID FIRST AND SECOND AREAL SURFACES BEING RESPECTIVELY AT DIFFERENT DISTANCES FROM SAID FIRST SURFACE OF SAID BLOCK, SAID SECOND SURFACE BEING FURTHER DEFINED BY SLOPING SURFACES WHICH JOIN SAID FIRST AND SECOND AREAL SURFACES, A PLURALITY OF SAID PASSAGES OPENING AT LEAST IN PART INTO SAID SLANTED SURFACES TO PROVIDE THEREBY SLANTED DISCHARGE OPENINGS OF SUCH PASSAGES EACH OF WHICH FORMS AN ACUTE ANGLE WITH THE AXIS OF THE RESPECTIVE PASSAGE AND CAUSING AT LEAST A PORTION OF THE COMBUSTIBLE GAS MIXTURE FLOWING THROUGH SUCH PASSAGES TO BE DIRECTED TOWARD THE ADJACENT DEPRESSED AREAL SURFACE, SOME OF THE PASSAGES OPENING AT LEAST IN PART INTO THOSE OF SAID FIRST AND SECOND AREAL SURFACES WHICH ARE NEAREST SAID FIRST BOUNDARY SURFACE.

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