US3089537A - Pot burners - Google Patents

Description

A. A. STRUIJ K May 14, 1963 PCT BURNERS Filed May 11. 1960 United States Patent Ofilice amass? Patented l t lay id, 1963 1 3,tl39,537 P91 BURNERS Antony Albertus Struijk, Beethoyenlaan 9, Hilversum, Netherlands Filed May 11, 1%9, Ser. No. 28,497 Claims priority, application Netherlands May 20, 1959 13 Qlaims. (Cl. 153-91) The invention relates to a pot burner with a pot with a bottom and a flame opening formed in an upper wall and lateral air inlet apertures arranged in the side wall of the pot.

Such devices are generally known. Up till now they consist of a cylindrical pot with a slightly concave bottom and a radial or generally radial upper wall, tapering slightly upwards and having a relatively wide central flame opening, below which in the side wall one or more circles of air inlet apertures are provided. The whole pot is surrounded by an air conducting jacket which is also generally cylindrical and joins with the side wall of the pot at the upper end by a ring-shaped upper wall and has a ring-shaped lower Wall with a central air inlet opening under the bottom of the burner. The pot space may be further subdivided into two or more compartments by one or more intermediate baflle walls with a central opening for increasing the regulation range of the burner. The intermediate baffle walls extend inward from the side wall approximately parallel to the upper wall. The pot is again provided with one or more circles of air inlet apertures in the side Wall under each intermediate baflle Wall. With these burners the evaporation of the fuel, which is admitted at the bottom, takes place mainly in the center of the lower portion of the pot space, therefore under the relatively wide flame opening and/ or the openings in the intermediate baflie walls. In consequence of the ascending force of the vapour this latter immediately ascends through these openings, so that the pot space is mainly filled with air and in this air space a gas column is created which rises centrally in a column the width of the flame opening and of passages of the intermediate baffle walls if present and comes in touch with the admitted air only at the circumference. As a consequence a destructive combustion takes place with a yellow flame with considerable soot formation (allowable limit soot index 8). For ameliorating the combustion, therefore, with this kind of burner it is also known to admit an additional amount of combustion air above the flame opening, but this necessitates a rather long flame space which makes the application of this kind of burner, for instance for hearths, ditficult, as with this kind of devices the height of the chimney must be within determined limits. Besides, the soot deposit in the chimney may be inconvenient and even dangerous as chimney fires and explosions in the chimney-shaft may be caused. Also, they need a rather high chimney-draft so that the air in the air conducting jacket is admitted centrally and has to flow through several sharp curves before it enters the pot space.

Also pot burners are known with an oblong pot and a slot-shaped flame opening. These pot burners may also be provided with an intermediate resistance wall. With this known construction the pot has a fully flat upper wall with a flanged flame opening, whereas the intermediate resistance wall consists of two parts sloping slightly upwards. The flame opening of the intermediate wall is approximately of the same width as the main flame opening and in mounted condition an air admitting slot is formed on both sides along the main flame opening for additional combustion air. The longitudinal walls of the burner pot are provided with rows of air inlet apertures from the top to near the. bottom. Also with this known burner the circumstances are such, that a band-shaped fuel vapour column is formed, which comes in contact with air only at the outside, so that in this case only a destructive combustion with yellow flame and soot formation can take place, whereas relatively high flame space is necessary.

Furthermore a round burner is known, of which the pot is of generally spherical form with a flattened portion serving as the bottom and a relatively wide flame opening lying opposite thereto. The spherical pot is cut through along a meridian plane parallel to the bottom and contains, about at the level of this meridian plane, a battle ring structure with a central opening. The partially spherical pot has on the outside of the. upper part an air conducting jacket merging with a slot under a ring-shaped upper Wall. The pot wall is, for the rest, provided with air inlet apertures in both parts. This construction works in the same manner as the first of the above described known constructions having a cylindrical pot and it therefore also gives a destructive combustion with a yellow flame and requires a rather high flame space and a rather strong draft.

The present invention aims at providing a pot burner in which the above drawbacks are avoided.

According to the invention this is obtained by making the pot generally ii-shaped in cross-section with the closed under portion forming the bottom, while the upper Wall in cross-section has converging parts beginning at the broadest part of the burner and running slantingly upwards and the upper wall parts define the flame opening, while the air inlet apertures are only provided in the widening lower part of the burner and may also be present over the flame opening, the whole burner being constructed and dimensioned in such a manner that during operation the pot is filled completely or practically completely with fuel vapour and the air flowing in through the air inlet apertures gives a stable hydroxylative combustion on the whole regulation range by this shaping of the pot, which in the round construction is mainly double conical, a pot space is obtained which is filled completely with fuel vapour when the passage through the flame opening in the upper part and in the intermediate baflle wall respectively and the direction of the incoming air are well calculated, and the fuel vapour will burn under hydroxylation by the incoming air. This hydroxylative combustion gives blue sootless flame, so that a combustion is obtained having a soot index 0 and requires practically no flame space. With the construction as a round burner, however, the capacity is limited since with greater dimensions the admitted air will soon no longer cover the flame opening. Therefore preferably the burner is carried out as an oblong burner with a relatively narrow oblong flame opening in the upper wall.- The burner further according to the invention has a generally trough-shaped lower portion diverging upwards and a mainly roof-shaped upper wall converging upwards to the middle plane. In this way a stably blue burning pot burner of practically any or every desired capacity can be made, which can be easily and favourably adapted to the available space, for instance in hearths, by arranging the burner with the longitudinal direction parallel to the front and rear sides of the hearth.

In burners with a sufliciently large capacity for heating purposes and for industrial purposes the flame opening is appropriately provided with an upstanding wall, in which air inlet apertures are also provided, the distance between these upstanding walls being such, that the air streams entering through the apertures in these walls will at least reach to the middle between these two upstand ing walls and at the utmost just do not touch the oppoa9 site wall. The air apertures in the diverging lower portion of the burner pot then serve for a pro-mixing of the fuel vapour during burning at full capacity, whereas the final combustion takes place in the flame opening by the air admitted at that place. In adjustable burners these air inlet apertures in the upstanding wall of the flame opening are appropriately closable in order to avoid a too great air admittance during working at reduced capacity.

When the pot space is subdivided by one or more intermediate baffle walls, the intermediate wall or walls extend in a roof-shape from the diverging side walls of the lower portion of the burner and with the under part belonging to it, they enclose a space which has generally the same shape as, or is similar to, the whole burner pot but is proportionally smaller and the flame openings be coming larger or broader at each higher level. This has a result that a burner with a very large regulation range of for instance 1:10 or more can be obtained which besides burns blue on the whole regulation range.

In practice the side walls of the lower part are made appropriately as a. flight of stairs with a number of steps corresponding to the number of parts into which the burner space is subdivided by the intermediate baflle walls. In this way, it becomes possible to use at least the lowermost of the horizontal parts of the side walls of the lower portion of the burner pot at the same time for supporting one or more roof-shaped intermediate baflle Walls. At the same time the possibility arises to arrange the air inlet apertures in the burner pot in or near the re-entering angles of the staircase-shaped side walls, whereby a favourable inflow of the air is obtained with possibly less resistance and without time consuming bending out of the edges of the air inlet apertures. In this case the air inlet apertures are appropriately drilled in such a manner through the side walls that they are directed to the mouth of the spaces formed by the roofshaped intermediate baflle walls or a little under it.

In the upstanding wall of the flame opening the air inlet apertures are appropriately drilled horizontally or slightly sloping upwards. The air currents flowing in through them then cover nearly the whole width of the flame opening, but are bent up at the end by the vapour stream flowing out in such a manner that they do not hit the opposite wall of the flame opening, so that this latter is not unnecessarily locally heated, whereby cracking of the fuel would be caused and the combustion would become destructive but, on the other hand, the space under the flame opening is closed by an air curtain and the combustion takes place thereby.

Preferably the air inlet apertures lie in the upstanding walls of the flame opening alternately, whereby the whole flame opening can be covered by the air inlet apertures for a complete combustion without the necessity of these apertures having to lie particularly near one another in each of the walls. The burner, however, can also be made in such a manner, that between the horizontal or generally horizontal air inlet apertures arranged opposite one another further air inlet apertures slanting upwards are provided. It has proved that this measure can be appropriate for meeting hum if present during working at full capacity, or anyway it can be of help for it.

The burner further possesses an air conducting jacket which, according to the invention, joins the upper edge of the upstanding walls of the flame opening at the top end and runs from there at first nearly parallel with the upper wall parts of the burner, sloping to the outside, preferably somewhat diverging in downwards direction, and then, after a gradual bend, straight or nearly straight downwards, laterally screening the under portion of the burner. Such a jacket, in cooperation with the shape of the burner, gives a very favourable flow of the air to the air inlet apertures with possibly less resistance, so that the inflowing air loses as little as possible of its velocity and a burner according to the invention can easily burn with natural draft. It has further proved that the burner remains stably burning blue with the draft fluctuations occurring in practice. While no particularly high chimney-shaft or other means for augmenting the draft in the chimney-shaft is necessary, a burner according to the invention can burn well without difficulties, and can also burn well on upper floors of houses, in which case the chimney-shaft is short. A draft however is absolutely necessary with the blue burner according to the invention; this is contrary to the known blue burners such as the sleeve type vaporizing burners.

In practice the side walls of the upper portion and the roof-shaped intermediate baflle walls or the connecting line of the end edges thereof for bent intermediate baflle walls, are carried out in such a manner that they make an angle of about -70", preferably of about -50", with the horizontal plane.

The invention will now be described with reference to an embodiment shown in the drawing by way of example. In the drawing:

FIG. 1 shows a cross-section of an oblong pot burner according to the invention with two intermediate bafile walls and an air conducting jacket,

FIGURE 1A is a fragmentary section similar to FIG- URE 1 showing a slightly different arrangement of air openings, and

FIG. 2 shows a top elevation of a burner according to FIG. 1, in which the air conduction jacket is omitted.

In the drawing 1 indicates the troughor guttershaped vaulted bottom of the burner pot to which the liquid fuel is admitted in known manner and in which this fuel is brought to vaporisation. This bottom part of the burner pot merges into side walls 2 generally slanting to the outside and which are partly continued in dotted lines at 2a and merge about in the middle of the height of the burner in a short vertical portion 3, 3a, which thereafter again runs up slantingly at an angle of about 50 at 4. At the upper end the upper wall parts 4 form the flame opening 5. Above it they are provided with upstanding walls 6 with a flange 7 extending outwards. The dotted lines 2a and 3a in the drawing give, with the joining lines 2, 3 and 4, the general shape of the burner. This burner, therefore, has mainly a double conical or angular bulging oblong shape. In the embodiments the side walls of the under part are however stair-step-shaped between the lowermost straight portion 2 and the short intermediate portion 3 with horizontal portions 8, 9 and 10 and vertical portions 11 and 12. The horizontal portions 8 at the same time serve for supporting a roof-shaped intermediate baflle wall 13. The roof-shaped intermediate baflle wall parts 13 are at an angle of about 40 and form a narrow passage 14 therebetween. In the re-entering angle between the side wall portions 2 and 8 air inlet apertures or openings 15 are provided, drilled in at an angle of about 50 to the horizontal, as indicated by the arrows 16. In this case the arrows 16 cross one another a short distance below the opening 14 in the center of the burner or in the longitudinal center plane of the oblong burner. As appears from the drawing, the lowermost pot space, which is closed at the upper side by the intermediate baflie walls 13, is generally similar to the total burner space. The lowermost portion of the burner therefore forms a stably blue-burning small pot burner with a flame opening 14. On the second step 9 of the stair-step-shaped side walls of the burner there rests a second roof-shaped intermediate baflle wall 17 forming a passage 18, the width of which is larger than the opening 14, but smaller than that of the flame opening 5, and which is carried out as a generally half-circle-shaped dome of which the chord lines 19 between the edges, which are shown in dotted lines in the drawing, are at an angle of about 50 with the horizontal plane. A row of air inlet apertures 20' is arranged in the horizontal portion 9 at each side near the junction of wall 11 with wall 9, the apertures in this case being drilled at an angle of as is shown by the arrows 21, so that they cross one another at a short distance below the opening 18 in the longitudinal central plane of the burner. Also the part of the pot burner under the intermediate battle wall 17, when the intermediate baffle wall 13 is ignored for a moment, again forms a pot space which is generally similar to the whole burner space.

In the re-entering angle between the side wall portions and 1'2, a row of air inlet apertures or openings 22 is arranged on both sides, w hich apertures or openings are also drilled at an angle of 45 as indicated by the arrows 23 which at the same time indicate the direction of the entering air. These air currents 2.3 meet one another at a short distance under the primary flame opening 5 in the longitudinal central plane of the burner. In the upstanding walls 6 of the flame opening 5, finally, further or additional air admitting apertures or openings 24 are drilled, somewhat sloping upwards. These air admitting apertures or openings can be closed with the aid of valves 25, if desired.

As is shown in FIG. 2, the air inlet apertures 24 are spaced alternately in the opposite upstanding walls 6, so that the air streams 24a flow alternately in opposite directions. Between these generally horizontally directed air inlet apertures, if desired, further air inlet apertures, directed slantingly upwards as seen in FIG. 1A, may be provided alternately and opposite the horizontal apertures or openings, whereby the quietness of the burner can be favourably influenced. The slanting air inlet apertures may be at an angle which may amount up to Gil-70.

Under the flange 7 of the upstanding walls 6 of the burner mouth the air conducting jacket 26 is connected, which runs down from the flange, slanting outwards, diverging a little with respect to the sloping upper walls 4 of the burner and merges with a gradual bend 27 at the level of the middle portion 3 of the burner in a portion running vertically downward.

The oblong burner shown has at each end a plane end wall 29, which can at the same time form the end wall of the air conducting jacket. For mounting the intermediate bafile walls 13 and 17 the burner is composed of two parts which are interconnected for instance at 30, but may also be connected e.g. above the step 19. The portion lying under the connecting place 30 is connected in a rigid and liquid-tight manner with the end walls, for instance by welding, at least with the bottom part 1, 2 up to the air inlet apertures 15.

However, with an oblong construction the pot can also be fully connected rigidly with the end walls 29 and form a unit as the intermediate baffle walls in this case each consist of two parts, which can be brought in easily from above through the burner mouth 5. The roof-shaped intermediate walls rest on supports arranged on the end walls 29. However with an adequate construction of the burner it is also possible to interconnect the two parts of the intermediate walls to arigid unit by narrow connecting strips at the ends and/or at one of more intermediate places.

As further appears from the drawing, the air inlet encounters very little resistance as even the air streams to the air admitting apertures of the flame opening have to pass through only two gradual bends \of less than 90, as is indicated by the arrows 31, whereas the air streams to the remaining burner spaces have to make only a single slight curve and besides the air is forced to the air admitting apertures by the walls of the steps. The burner therefore has only a very low air resistance, so that it can also work undisturbedly at a relatively low draft. The air sucked through the burner by the draft therefore encounters very little resistance on its way through the burner whereby with a low draft very strong air streams enter into the burner pot through the perforations in question so they can be accurately directed to the right places and by the great air velocity cause the eddy currents in the mixing chambers which are necessary for a good mixing of air and fuel vapour for obtaining a hydroxylative combustion.

The working of the burner is as follows:

When the burner works at full capacity the valves 25 are in the open position as indicated in FIG. 1. The fuel vapor-ises on the gutter-shaped bottom 1, 2 and is mixed with the air flowing in through the air admitting apertures '15, 2t and 22. The amount of air admitted is insuflicient for obtaining a combustible fuel-air-mixture. Combustion then only occurs by the admittance of air through the air admitting apertures 24 in the upstanding walls 6 of the burner mouth 5. The combustion occurs completely and stably with a blue flame, that is, with a large number of flame tongues around the air flowing in through the apertures. The combustion is completely sootless, while no flame space over the burner mouth is necessary. It is possible to arrange a number of glowing members over the burner mouth, on which no deposit is formed. The draft, which the burner requires, is about one-half of that of a normal pot burner. The flame is, besides, insensitive to fluctuations of the draft. When the burner is regulated downwardly, the flame gradually sinks down into the burner, but the burner remains burning with a blue flame. At a definite moment the air admitting apertures 24 are no longer necessary and it is possible to close them by the valves 25 in order to prevent the sucking in of unnecessary The burner then remains burning with a blue flame with the air admitted through the air admitting apertures 15, 20 and 22. When the burner is further regulated, the opening 18 will serve as flame opening. Thereafter, on further regulating, the flame sinks to the secondary flame opening 14 and when still further regulated it sinks into the space which is closed by the intermediate baffie walls 13. Thus the burner can be regulated up and down in a proportion of 1:10 or more, during which a stable hydroxylative combilStiOil, thereforewith a blue flame, continuously takes p ace.

The invention is described above with reference to an operative example, but it is not limited to the embodiment shown. For instance the half circular intermediate baffle wall 17 can be replaced by a roof-shaped intermediate wall with plane, or less bent plates. Furthermore, under special conditions it is possible to alter the slant of the roof-shaped intermediate baflle walls and of the upper wall of the burner pot. Also the direction of the air inlet apertures may be changed to some extent. The roof-shaped intermediate baflle walls 13 can also be made more or less vaulted, as well as the sloping upper walls. An essential is, that the intermediate walls enclose spaces which are similar or generally similar to that of the whole burner and the openings in the intermediate baflle walls are so dimensioned that these spaces will each, because of the air streams directed on the flame openings belonging to it and which create a compression at that place, always provide the conditions for a hydroxylative combustion.

I claim:

1. A pot burner comprising an elongated trough shaped lower portion formed with upwardly diverging walls symmetrically on each side of a center plane, roof shaped upper portions extending upwardly from the upper edge of each wall of said lower portion and converging upwardly to bound, with said lower portion, a generally diamond shaped enclosure, said upper portions terminating short of the central plane of said lower portion to form a flame opening, primary air openings solely in the diverging walls of said lower portion, said air openings having means to direct inflowing air upwardly and inwardly from each side of said lower portion in a plane, the planes of said inflowing air intersecting below said primary flame opening, said converging upper portions terminating at said primary flame opening in opposed generally parallel upstanding walls, said upstanding walls being provided with additional air inlet openings to direct 3 air across said primary flame opening in planes normal to said center plane.

2. The pot burner of claim 1, in which further additional air inlet openings slanting upwards are provided between the generally horizontal air inlet openings arranged opposite one another.

3. The pot burner of claim 1, having an air conducting jacket and in which the air conducting jacket at the upper end joins the upper edges of the upstanding walls of the primary flame opening and the walls of said jacket extend from there first downwardly at each side slanting outwards approximately parallel with the side walls of the upper portion of the burner and then with a gradual bend extends approximately straight downwards screening the under portion of the burner.

4. Apparatus according to claim 1, in which the pot space is subdivided by at least one pair of intermediate resistance walls, the intermediate resistance walls extending from the diverging side walls of the trough shaped lower part, and slant upwardly toward the center plane to enclose, with the lower portion corresponding to it, a space which is proportionately smaller than and generally similar in section to that of the whole burner, the flame opening in each resistance wall being narrower than any flame opening above it, the flame opening in the resistance wall closest to said primary flame opening being considerably smaller than said primary flame openmg.

5. Apparatus according to claim 4, in which the side walls of the lower portion are made stairstep-shaped with a number of steps corresponding to the number of intermediate resistance walls that divide the interior of the burner.

6. Apparatus according to claim 5, in which the lowermost of the horizontal parts of the stairstep shaped side walls of the lower portion of the burner pot serves at the same time for carrying one of said roof-shaped intermediate resistance walls.

7. Apparatus according to claim 5, in which the air inlet openings in the burner pot are arranged at the reentering angles of the stairstep-shaped side walls.

8. Apparatus according to claim 7, in which the air inlet openings are directed generally to the mouth of the spaces formed by the roof-shaped intermediate resistance walls.

9. The pot burner of claim 1, in which each of said additional air inlet openings in said upstanding walls is so spaced as not to be opposite an air inlet opening in the opposed wall.

10. The pot burner of claim 9, in which means are provided to close said additional air inlet openings in said upstanding walls.

11. The pot burner of claim 1, in which at least one pair of intermediate upwardly converging roof shaped elements is provided below said primary air openings and lying generally parallel to said upper portions, said pair of intermediate elements terminating short of the center plane of the burner to provide a secondary flame opening narrower than said primary flame opening, the space enclosed by the lower portion of said trough shaped lower portion and said pair of intermediate elements being substantially the same shape as, but proportionately smaller than, the space enclosed by the entire trough shaped lower portion and said roof shaped upper portions, and second air openings solely in the diverging walls ofrsaid lower portion having means to direct inflowing air upwardly and inwardly from each side of said lower portion in a plane, the planes of said inflowing air intersecting closely below said second flame opening.

12. The pot burner of claim 11, in which at least two pairs of intermediate upwardly converging elements are provided, each said pair of intermediate elements providing a flame opening proportionately smaller than the flame opening of the pair of roof shaped elements positioned above it, and being provided with air inlet openings having means to direct air from each side of said trough shaped lower portion in planes intersecting just below the corresponding flame opening.

13. A pot burner comprising a bottom portion having upwardly diverging walls on each side of at least one plane of symmetry, an upper portion having converging walls extending upwardly and inwardly from the upper edge of said upwardly diverging walls, said converging walls terminating short of said plane of symmetry to provide a primary flame opening, said upper and lower portions bounding an enclosure of generally diamondshaped cross section, at least one intermediate resistance wall extending from the diverging walls of said lower portion below the upper edge thereof and converging upwardly and inwardly generally parallel to said upper portion to provide a secondary flame opening at the top edges of said resistance wall to enclose, with the part of said lower portion corresponding to said resistance wall, a space that is generally diamond-shaped in cross section proportionately smaller than, and generally similar in section to that of the entire burner, the secondary flame opening in said intermediate resistance wall being smaller than the primary flame opening of the entire burner, and air openings solely in said diverging walls of said lower portion both above and below said resistance. wall including means to direct inflowing air upwardly and inwardly into the generally diamondshaped enclosures so that the streams of air inflowing through said openings intersect each other closely below the corresponding primary or secondary flame opening.

References Cited in the file of this patent UNITED STATES PATENTS 2,212,078 Sabins Aug. 20, 1940 2,214,670 Gilmore et a1. Sept. 10, 1940 2,241,470 Miller May 13, 1941 2,244,766 Cooper June 10, 1941 2,311,469 Pruitt Feb. 16, 1943 2,337,673 McCurtain Dec. 28, 1943 2,422,209 Reeves et al. June 17, 1947 2,428,009 Breese Sept. 30, 1947 2,494,104 Piatt et al. Jan. 10, 1950 2,519,570 Hayter Aug. 22, 1950 2,538,911 Reeves Ian. 23, 1951 2,581,238 Cauley Ian. 1, 1952 2,638,160 Thomson May 12, 1953 3,017,921 Stierlin Jan. 23, 1962 FOREIGN PATENTS 148,864 Australia Nov. 3, 1952 1,101,121 France Apr. 13, 1955 OTHER REFERENCES Handbook of Oil Burning, pub. by Oil-Heat Institute of America Inc, copyright 1951, pages 174 and 175.

Claims (1)

1. A POT BURNER COMPRISING AN ELONGATED TROUGH SHAPED LOWER PORTION FORMED WITH UPWARDLY DIVERGING WALLS SYMMETRICALLY ON EACH SIDE OF A CENTER PLANE, ROOF SHAPED UPPER PORTIONS EXTENDING UPWARDLY FROM THE UPPER EDGE OF EACH WALL OF SAID LOWER PORTION AND CONVERGING UPWARDLY TO BOUND, WITH SAID LOWER PORTION, A GENERALLY DIAMOND SHAPED ENCLOSURE, SAID UPPER PORTIONS TERMINATING SHORT OF THE CENTRAL PLANE OF SAID LOWER PORTION TO FORM A FLAME OPENING, PRIMARY AIR OPENINGS SOLELY IN THE DIVERGING WALLS OF SAID LOWER PORTION, SAID AIR OPENINGS HAVING MEANS TO DIRECT INFLOWING AIR UPWARDLY AND INWARDLY FROM EACH SIDE OF SAID LOWER PORTION IN A PLANE, THE PLANES OF SAID INFLOWING AIR INTERSECTING BELOW SAID PRIMARY FLAME OPENING, SAID CONVERGING UPPER PORTIONS TERMINATING AT SAID PRIMARY FLAME OPENING IN OPPOSED GENERALLY PARALLEL UPSTANDING WALLS, SAID UPSTANDING WALLS BEING PROVIDED WITH ADDITIONAL AIR INLET OPENINGS TO DIRECT AIR ACROSS SAID PRIMARY FLAME OPENING IN PLANES NORMAL TO SAID CENTER PLANE.

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