US2375625A - Combustion apparatus - Google Patents

Description

My l8, 1945. L F. CONWAY f COMBUSTION APPARATUS Filed Dec. 27; 1940 1 heretofore Patented May' 8, 1945 OFFICE CODIBUSTION APPARATUS Application December 27, 1940, Serial No."371,86`2 3 claims.' (ci. '15s- 110) This invention relates to the combustion of iiuid fuelI and, particularly, to an apparatus for.

the combustionof hydrocarbon gas suchas nat- `ural gas with a luminous flame.

Luminousfilame burners `have been known but have been characterized by a limited thermal capacity compared to burners producing a nonluminous or clear name. It is generally accepted that the production of a luminous flame necessitates crackingof the carbon `from hydrocarbon fuel by a slow burning process in which the hydrogen burns first and the carbon goes into `atomicnform and thereafter l burns slowly. rlihis form of combustion has here` by introducing` tofore been generally obtained gas and air streams along parallel lines at equal low velocities so that they mix slowly over the area of contact of the two streams and combustion starts in that area. Known types of lumi- `nous-flame burners, however, have beenlimited in theirapplication to large furnaces in which the amount of heat liberated per cubic foot of furnace volume is relatively low, i. te., less than 35,000 B, t; u. per hour.

I have invented a novel apparatus forthe com bustion of hydrocarbon" fuel with" a luminous arne, adaptable to furnaces requiring a heat input in excess of the ngure above mentioned, e. g., up to 70,000 B. t. u. per hour per cubic foot of combustion space. In a preferred practice of the` invention, I introduce a fuel jet substantially centrally of an annular air stream and impart suiiicient turbulence to the adjacent layers of fue] and air near the plane of their ,initial contact to cause rapid mixing thereof without materially af-l fecting the central core of the fuel stream or the outer layers of the air` stream. The air is in- Avi troduced at a velocity higherthan that of the gas and the condition of `turbulence at the zone of initial contact may conveniently be obtained by creating a low pressure or `partial vacuum condition in said zone. The rapid mixing of the adjacent layers of fuel andyair creates an annular column of combustion gases, the heat from which cracks the remaining fuel, releasing the carbon in atomic form to produce a luminous flame. The cracked fuel and the remaining air are then mixed gradually on continued flow and combustion spreads quickly over the entire secn tion of the stream of air and fuel mixture.

The method described above is claimed in my Patent 2,360,548 granted October 17, 1944, on a divisional application.

The apparatus for effecting combustion in the manner explained above preferably comprises an the tion through a' complete burn `2!) and fis provided with holes passage leading to acombustionspace and hav-` ing a Wall provided with ports for admitting air from the chamber to the passage. A fuel tube coaxial with the passage is slidable through the wall of the air chamber and is provided with an annular baffle adjacent the discharge end thereof. l The tube is retractible to a position in which the baflle is adjacent the chamber Wall,`

Further novel features and advantages of the invention will become apparent during the fol lowing detailed description of theapparatus and method briefly outlined above, with referenceto accompanying drawihg illustrating the method diagrammatically `and showing a preferred embodiment of the apparatus and certain modifications. In the drawing,

`Figure lis a central vertical longitudinal secer embodyingthe principlesof my'invention; and

Figure 2 is la transverse 'sectional view taken substantiallyalong the plane of line VI-VI of Figure 1. c

i Referring now in detail tothe drawing I have r there shown a complete `burnerindicated gener- -ally at 25 `associated with a" port block 26 which may be assumed to formpart` of a furnace wall 21. The burner 25 comprises generally an air `chamber 28. having a flange 293011 one side therethe chamber 28 through an opening 3| in the rear wall thereof. A frusto-conical wall 32`extends inwardly into `the chamber 28 from` theflange 33 uniformly distributed circumferentially thereof. It will be apparent that this construction, when airis supplied through the pipe 30,` will deliver air to the port block in uniformly distributed condition.`

A fuel chamber 34 is formed by an annular wall 35 extending inwardly from the rear of the air chamber to the frusto-conical wall 32 and a cup shaped casting 36 secured to the rear wall of the air chamber. The casting 36 has a hole 31 therein tapped to receive a fuel pipe 38. A fuel tube 39 is slidable through an opening in a wall 40 extending inwardly from the annular wall 35 and the frusto-conical wall 32. An adjusting rod 4I extends through the rear wall of the casting 36 having a gland 42 therein. The

\ outer end of the rod has a knob 43 thereon while the inner end is secured to a spider 44 `in the inner end of the tube 39. The tube 39 is provided with an external annular baille in the form of a ring 45 secured thereto adjacent the discharge end thereof.- The width of the ring is somewhat less than the radius of the tube 39. The rear outer edge of the baffle is beveled as at 46.

With the fuel tube 39 in the position illustrated in solid lines it Will be apparent that air supplied to the chamber 28 through the pipe 30 will flow into the port in the block 2B through the holes 33 and be distributed uniformly overythe annular area of the section of the port between the tube 39 and the block. Fuel supplied through the pipe 38 ilows into the chamber 34 and the tube 39 and is thereby introduced centrally of the annular air-stream. Thebaille 45 creates the condition of turbulence in the inner layers ofthe air stream resulting from the partial vacuum or low pressure condition beyond the baille .and causes partial mixing of the fuel and air adjacent their point of initial contact in thev manner already explained. This .initial combustion cracks at least a portion of the remaining fuel and lthereby imparts a high degree of luminosity to the flame. The remainder of the fuel and air become rapidly mixed and combustion proceeds to completion.

If combustion with a clear non-luminous flame is desired, `it is only necessary to pull back on the knob 43. When the tube 39 and baille 45 are in the positions indicated in chain'lines, the baille does not affect the flow of the air stream. Instead of an annular stream of Yair coaxial with the port in the block 26, the holes 33 create a plurality of air jets directed inwardly into a central fuel stream issuing from the tube 39. The angularity of the air jets relative to the fuel stream causes' immediate `mixture of all the gas and air so that rapid combustion with aclear flame ensues.

It will be apparent from the foregoing description and explanation that the invention is characterized by numerous advantages over combustion apparatus known heretofore. yIn the first place, the burner of my invention permits the production of a luminous llame with higher lfuel and air velocities than have been possible heretofore whereby I am able to obtain a greater heaty input per minute per cubic foot of combustion space. This is possible because I eiect quick mixing of a. portion of the fuel and air' for combustion to effect the cracking of the remainder of the fuel. This is accomplished by producing the turbulence which results from -the low `pressure or partial vacuum condition created adjacent the point of initial lcontact vbetween the fuel and air. After the initial combustion and cracking, the remaining fuel and air mix rapidly because the turbulence at the point of initial contact carries over into the latter stages of combustion, so that combustion proceeds to completion with a. highly luminous flame. By the apparatus disclosed, it s possible to obtain a heat liberation per cubic foot of combustion space of about 70,000 B. t. u. per hour, which is comparable to that obtained with conventional non-luminous burners.

In addition to providing a luminous llame burner which is novel in constructionand operation, the invention also provides a `burner which may be converted by simple adjustment so that it produces a clear non-luminous flame.

Although I have illustrated and described but a ypreferred embodiment of the apparatus of my inl vention, it will be understood that changes may be made in the construction and operation disclosed without departing from the spirit ofthe invention or the scope of the appended claims.

i Iclaim:

1. Combustion apparatus comprising a wall having `a passage therethrough, an air chamber adjacent the outer end of said passage, said chamber having a Wall overlying the outer end of said passage, ports in said chamber wall admitting air from said chamber to said passage, a fuel tube substantially coaxial with said passage, slidable through said chamber wall, and discharging into .said passage and an annular baille extending around said tube adjacent the discharge end thereof, said tube being retractible to a position in which said baille is adjacent said chamber wall and out of the path of the air traversing said ports.y

2. Combustion apparatus comprising a furnace Wall having a port extendingy therethroughcomu .muncating with a combustion space inside the wall, and a single fuel tube projecting into said port substantially coaxial therewith,'said tube being open across its full diameter and free from obstruction at its discharge end, and an external baille ring on said tube substantially at said end, a wall extending across said port adjacent the outer end thereof having holes spa-ced around said tube for the entrance of air,lsaid tube being retractible in said `passage to a position in'which said baille is adjacent said last-mentioned wall and substantially out `of the path of the air entering through said holes. f y l 3, The apparatus .defined by claim 1 characterized by said chamber Wall being frusto-conical kand disposed with its smaller end outwardly.

LEON F. CONWAY.

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