US2117881A - Fuel oil burner - Google Patents

Description

May 17, 1938. 4 E. E OHLER' 2,117,881

FUEL on. BURNER Filed Nov. 9, 193s I Il 5L l I v {five/776A?- l "4 f//ne/ Goe/er if fmf/@myee Patented May 17, 1938 UNITED STATES PATENT oFElcE FUEL OIL BURNER Elmer E. Goehler, Portland, Orex. Application November 9, 1936, Serial No. 109,904

4 Claims.

This invention relates to burners for burning atomized fuel oil. Specifically it relates to that type of fuel oil burner in which oil is furnished under pressure to an atomizer, a current of air provide burner apparatus to produce a wide flame of short axial length to the end that such burner apparatus may be installed in a short furnace and yet cause the combustion of fuel in suspension and not in contact with the furnace walls.

As is well known, fuel ofv the kind here contemplated, generally designated as Diesel oil must be burnt in suspension, except at a considerable sacrifice in economy. Since fuel of this general type must be gasiiied before ignition, if it is to be burnt in suspension, an additional object is to provide a means that will gasify all of the liquid fuel fed to it while the fuel is in sus# pension.

The invention herein consists in using the known scroll shaped casing, similar to those used in blowers or turbines, in combination with a thin plate provided with an orifice axially of the casing and superposing a frusto conical Vexpansion chamber, provided with a central circular orifice, with means for forcibly delivering oil fog in a plane, angular to the axis of the last named orifice.

Additional objects are simplicity, low cost of construction and total absence of fragile parts likely to deteriorate with use, and other objects that will be apparent from the description and the appended claims.

The underlying principle of the invention is based on the physical fact that there is always a low pressure area in the center of a whirling mass of air, and that the partial vacuum thus created demands to be satisfied and when used in an oil burner as described will pull particles of fuel back into the center of the combustion zone, from above, so long as they retain any weight.

I attain the objects outlined bythe structure illustrated in the following drawing, in which,-

Fig. 1 is a plan or top view of my new burner;

Fig. 2 is a section on the line 2--2 of Fig. 3;

Eig. 3 is an Orthographie projection of Fig. 1;

Fig. 4 is a section on the line 4-4 of Fig. 3 showing the' important diaphragm 1; andv Fig. 5 is a vertical section on the line 5-5 of Fig. 1 except that the electrodes 5 and 6 are disf placed from the preferred position to show both of them, placement being correctly shown in Figs; 1, 2 and 4.

In the drawing, I is a scroll shaped casing that in general resembles that used in a certain type of fan or the scroll casing of a centrifugal pump, 5 except that the external nozzle A2, receives air under pressure from an external source not shown.

.'Ihe bottom of the casing is closed by a plate 3, that serves to support the usual pair of vignition electrodes 5 and 8 in case this type of starting apparatus is desired.

Partially closing the upper part of the casing i, is a diaphragm member 1, provided with an approximately circular opening .8. Superposed on 15 the diaphragm 1, is an expansion chamber defined by a short cylindrical wall 9 and a converging wall Ill, that delimits a hollow frusto conical outlet Ii, symmetrical with and axially in alignment with the opening 8, in the diaphragm 1.

The opening 8, should be very closely restricted to comparative size with the top of the frusto conical outlet.' 'I'he short cylinder l2, if very "short, improves the action of the burner, but

may -be dispensed with without departing from 25 the mode of operation in any large degree.

What the wall 9, the conical wall i0 and the short cylindrical wall I2, really amount to is the inlet end of a Venturi tube.

The atomizer ll and the electrodes 5 and 6 30 need no 'description as they are well known, except that the atomizer is preferably a 60 de gree nozzle type that will deliver the oil fog about as indicated in Fig. 3. l

In practice, the casing is furnished with the 4requisite amount of air to support combustion of the fuel required to generate the required heat, with very little excess. Upon delivery with suitable velocity to the casing4 l, it of course immediately assumes a spiral the opening 8 as a means for exit, through which it passes, without substantial diminution ofvelocity, into the expansion chamber where the inequality of its whirling motion is tempered and equalized. What is meant 'ing 8, be uncovered by removing the superposed4 parts. the air flow tested by chemical smoke will show a very irregular delivery and the main body of the smoke will whip rapidly around the openmg.

By placing .the expansion chamber with its Venturi contraction as shown and described, the discharge from the outlet Il is uniform so far as the eye can distinguish, even when oil isabeing supplied and burned, but without substantial im- 55 the fuel oil pipe l, and 1o whirling motion, using 40- here is that if the openpairment of the whirl originally imparted by the casing l. In any event, a very pronounced whirl is evident. This whirl, as previously noted, creates and maintains a low pressure area. in the center of it that probably extends nearly to or below the line 20. (See Fig. 5.)

'I'his low pressure area or partial vacuum is less pronounced and the burner correspondingly less eiectve if the short cylinder I2 is omitted. Also there will be a flatter spread to the flame, which is usually undesirable.

With it, the delivery of air which determines the location of the zone of combustion is substantially that shown in Fig. 3 by the dotted lines designated by "C. It will be understood that this is a vertical section as with the structure, and that in plan the combustion zone is a ring surrounding the burner outlet.

The ring of re surrounding the outlet immediately assumes a very high temperature upon ignition of the oil spray, while the center (in plan) is clark, and looking down upon the :llame one can sometimes actually see the burner tip, though the extreme brightness of the ring interferes.

' It will be noted from the diagrammatic indication of the manner of fuel combustion in Fig. 3 that initially a very small part of the atomizer discharge engages the outgoing air over the rim of the cylindrical wall I2. With a good atomizer,

kept clean, the very iine oil i 1g rises a ver-yl short distance above the burner center, ordinarily a matter of inches, from whence it falls downwardly and mostly outwardly into the extremely hot ring of re, generated by the small quantity of oil originally -intercepted by the air blast and burned in suspension by anexcess of atmospheric oxygen as will be immediately apparent; this falling of the center oil particles being strongly promoted by the low pressure area in the center of the burner outlet.

The oil pipe and the nozzle should be in the center of the apparatus as shown and the elecr trodes, though necessary, are more or less of a nuistance in disturbing the smoothness of the air flow. Theyv are best disposed as shown in Figs. 1, 2 and 4.

What I claim as my invention and desire to secure by Letters Patent, is,-

. 1. In an oil burning apparatus, a scroll shaped air receiving casing provided with a tangentially placed air inlet opening, a thin plate closure member for one side of the casing, said plate being provided with an axial orifice, a frustoconical expansion chamber superposed on the thin plate member, said chamber being provided with a top opening spaced above and substan tially of the same size as the orice in the thin plate, and means in the upper part of the frusto conical expansion chamber for discharging a spray of atomized fuel through said top open ing and at a wide angle to the axis thereof.

2. The structure as claimed in claim l with the addition of a short cylindrical Wall member surrounding the top opening of the expansion chamber. l

3. In an oil burner, a scroll shaped casing of the character described having a tangential air inlet opening, said casing having a top provided with an axially located port, an expansion chamber superposed on said top, said chamber having a lower portion of greater area than the area of said port and surrounding said port, said chamber also having converging circular walls terminating in an opening in spaced axial alinement with said port, a cylindrical Wall surrounding the last n-amed opening and dening an` air discharge nozzle and means for discharging oil fog into the air discharged from said nozzle.

4. In oil burner appara-tus, a scroll shaped casing that is provided with a tangential air inlet, a bottom closure for said casing, a partial top closure for said casing that is a thin plate provided with a centrally disposed orifice, `frusto conical walls larger in inner bottom diameter than the orifice in the plate that are superposed on the plate to provide an air outlet spaced above the said orice and means for delivering atomized fuel oil into said air outlet at a Wide angle to the axis thereof.

ELMER E. GOEHLER.

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