US2330190A - Combustion method for oil burners - Google Patents

Description

' Sept. 28, 1943. R. w. BECKETT COMBUSTION METHOD FOR OIL BURNERS Original Filed Feb. 4, 1938 3 Sheets-Sheet 2 INVENTOR REGINALD W. BECKETT ATT Sept. 28, 1943 R. W. BECKETT COMBUSTION METHOD FOR OIL BURNERS 3 Sheets-Sheet 5 Original Filed Feb, 4, 1938 I, INVENTOFZ REGl NALD w. BECKETT WVhc ATTORNEYS Patented Sept. 28, 1943 STATES PArEr OFFiCE Original application February 4, 1938, Serial No.

188,731. Divided and this application February 5, 1940, Serial No. 317,246

4 Claims.

This invention relates to combustion methods, and more particularly to an improved method of burning fuel in oil or other liquid fuel burners of the gun type in which a blast or current of combustion air is forced past and around a nozzle ejecting fuel under high pressure and into a furnace or other combustion chamber. The present application is a division of my co-pending patent application Serial No. 188,731, filed February 4, 1938, and now matured into Patent No. 2,310,274, February 9, 1943.

It is an object of the invention to provide an improved method of combustion in which a spiral motion is imparted to the combustion air and the air is given an increased turbulence or agitation in the region of the fuel ejecting nozzle so that an improved mixing of the fuel and air is produced and an atomized mist of highly combustible fuel is projected from the mouth of the burner.

Another object is to provide a generally improved combustion method which is economical and may be performed or utilized in a burner of relatively simple design and construction and one which is inexpensive to manufacture. Other objects and advantages of the invention will become apparent from the following detailed description of the method and a suitable burner or apparatus for carrying out the method made in connection with the accompanying drawings, in which:

Figure 1 is a side elevational view partly in section and with parts removed showing a burner in position for operation according to the method of the present invention in a conventional furnace and taken substantially on the line l--| of Fig. 2;

Fig. 2 is a rear elevational view of the burner with parts broken away;

Fig. 3 is a front elevational view of the burner;

Fig. 4 is a fragmentary sectional view taken substantially on the line 2-4 of Fig. 1;

Fig. 5 is a transverse vertical sectional view with parts removed taken substantially on the line 5-5 of Fig. 1; and

Fig. 6 is a fragmentary detail view in section taken substantially on the line 6-6 of Fig. 1;

Referring to the drawings by numerals of reference, which indicate like parts throughout the several views, the burnerillustrated comprises a pedestal or base, indicated generally by the numeral l, which is surmounted by and supports a main body portion or housing, indicated generally by the numeral 2. A horizontally disincluding motor 7, fuel pump and pressure regu lator 8, blower 9 of the sirocco type, and cover plate It. The blower 9 is actuated and supported .by shaft H of the motor I which also actuates the fuel pump. The circular cover plate II] has a running-or clearance fit on the shaft l2 between the motor I and blower 9.

Theg'blower 9 is received in a chamber it formed in the upper portion of the housing 2 and forces air downwardly through a throat [5 tan-- gentially into inlet end N5 of combustion air passage way ll extending longitudinally through the bottom of the housing 2 and the air tube 3.

The fuel pump and pressure regulating de vice 8 drawliquid fuel through supply conduit l8 and force it under relatively high pressure through fuel pressure conduit l9 having a flexible loop 20 into fuel pipe 2| supported by bracket 22 and spider 23 in the air tube 3. A vaporizing or spray nozzle 25 is secured on the end of the fuel pipe 21 at the discharge end of the air tube 3 so that its outlet orifice 26 is disposed substantially in the plane of the smallest cross-sectional area portion of a burner head 21, to be later described. Air forced through the passage-way H by the blower 9 and moving in a helical path. commingles with the oil spray emerging from the nozzle orifice 26 to form a mist of finely dis persed oil particles which burn in combustion chamber 28 of the heating unit such as a domestic furnace.

The. housing 2 is symmetric in external appearance and of generally ovate form as viewed from either end. It is carried in an upright position on the base I, being of a materially greater height than width and of a materially greater width than length. The housing is of substantially uniform length from top to bottom and has a top wall 30 of generally rounded form merging into relatively straight vertical side walls 36 and 32. Inwardly curving or rounded bottom walls 33 and 34 extend downwardly as continuations of the side walls 3| and 32 and terminate in a downwardly directed socket 35, to be later described. Rear end wall 36 carries the bracket which supports the removable motor unit, and front end wall 37 carries the air tube 3 as men- -tioncd above.

The blower chamber [4 (Fig. 5) is of the form commonly employed with rotary blowers of the s'iroeco type having axially extending blades, and partially defined by a curved internal wall or partition 38 which extends between the end walls lit and Si of the housing 2 from a point 39 where it is formed into the top wall 30 of the housing at substantially the center thereof downwardly to the left in a circular fashion and then to the 3 ht, as viewed in Fig. 5. The lower end of the i 38 extends beyond the middle of the housing a d to cut off Q of the throat 15. The radial ice between the peripheral margin of the roblower 9 and the walls of the chamber l4 sively increases from the cutoff 40 in a e direction around the rotational axis of the blower substantially to the throat l5. This increase in the free radial cross-sectional area of the housing available for the flow of air is in the direction of rotation of the blower rotor 9, indicated by the arrow of Fig. 5.

In the bottom of the housing 2 is formed the inlet end l6 of the passage IT, as previously mentioned. Air moving through the throat in a downward direction is directed tangentially into the passage portion by the curved bottom wall B l of the housing, the inside surface of which gradually approaches the passage l6 and is tangent thereto at substantially the bottom of the housing.

One side of the inlet end l6 of the passage, opposite the throat i5, is defined by an internal wall or partition 42 which starts substantially at the bottom center of the housing 2 where it is con- .1e red to the lower part of the bottom wall 33,

l indicated at 43, and is then curved upwardly to the left and then to the right in a clockwise direction following the general curvature of the passage E1 in the tube 3. The upper end of the partition 32 and the lower end of the partition 38 are joined by a short, vertically disposed partition which partially defines the throat (5. The partition 42 is curved or sloped longitudinally of the inlet portion N3 of the air passage as shown in Figs. l and 6. This curvature is progressively increased from the lower portion 43 to the top porn where the partition 52 joins the vertical partition i l. The margin 55 of the partition 62, adjacent the end wall 36 of the housing 2, progressively approaches the axis of the air passage i while the margin 46 of the partition 32, ad-

nt the end wall 3? of the housing, remains substantially flush with the internal wall of the .11 ube 3. Air entering the inlet l5 of the air pass e il tangentially through the throat i5 is l in a helical path to flow through the tube a. The opening in the front end wall 3'! of the liousing 2, which is covered by the air tube 3, is substantially the same effective cross-secshape and area as the corresponding end of the air passage in the tube 3 so that the Walls of the inlet portion iii are substantially flush with the wells of the air tube 3. No portion of the inlet end it of the air passage H, which is formed housing 2, is of greater effective cross-sectit area than the portion of the passage I"! which is formed in the tube 3. Preferably, there is a progressive decrease in the effective crossvlion-iii area inlet portion 18 from the plane Tube 3 is substantially circular in cross-section throughout its length and has a portion 4! of cylindrical form and uniform diameter adjacent the housing 2 which merges into a tapering portion 48 which extends toward the discharge end of the tube where a second cylindrical portion 49 of uniform internal diameter and relatively short axial length is formed. The walls of the tube 3 are relatively thick and of heavy section at the discharge end thereof, preferably being in the form of an integral, thick-sectioned, annular collar 50 which reinforces the tube end and receives the screws which hold the head 21. A circular, radially directed flange 53 is integrally formed about the large diameter end of the head 27 and circumferentially abuts against the annular collar or thickened section 50 on the discharge end of the tube 3. A pair of screws 53 extend through suitable drill holes in the flange 53 and are threadedly secured in the collar 50 to clamp the head 21 in heat exchanging circumferential contact with the collar.

Another pair of screws 5| extend through an annular holding ring 52, disposed about the head 21, through the flange 53 and are threadedly received'in the annular thickened collar portion 50 at the discharge end of the tube 3. The ring 52 and flange 53 preferably have substantially the same outside diameter and the ring is axially movable over an external cylindrical portion 54 of the head 21 which extends forwardly from the base of the flange 53. Between the ring 52 and flange 53, and seating on the cylindrical portion 54 of the head, is an annular ring 55 of fireproof fibrous material such as asbestos. This ring is clamped between the holding ring 52 and flange 53 by the screws 5| which also hold the head 21 to the tube 3.

Combustion air forced through the passage l! in a spiral path is gradually accelerated in velocity by the general tapering form of the tube 3 which decreases in cross-sectional area towards the discharge end. The head 2'! is formed to present a substantially continuous circular shoulder 56 to the advancing air and effects an agitation thereof which is beneficial in forming a suitable combustible mixture with the fuel oil. This shoulder 56 is adjacent the small diameter cylindrical portion 59 of the passageway H in which is located the spider 23. From the shoulder 56 the head 21 is tapered and the internal walls thereof converge to provide a progressively decreasing, substantially circular cross-sectional area in the direction of air flow. At substantially the region of smallest cross-sectional area the head 21 is formed with a shoulder 51 which further turbulates or agitates the moving air. From the shoulder 51 to the extreme end of the head 2'! there is an outwardly tapering outlet or mouth 58.

A pair of ignition electrodes 68 and G9 are disposed longitudinally through the passageway l7 slightly above and on opposite sides of the oil pipe 2|. These electrodes are mounted in porcelain insulators 70 held in a clamp H on the top of the bracket 22. The forward ends of the electrodes 68 and 69 are directed toward one another in the region of the orifice 26 of the nozzle 25 so that a spark across the electrodes ignites the atomized fuel.

A transformer, carried in a box 73 disposed against the rear end wall 38 of the housing, furnishes high tension current to the electrodes 68 and 69. Conductors H and i5 enclosed by insulators '16 extend into the inlet end iii of the air passageway H from the transformer box "I3 through an opening 11 formed in the rear wall ward the brushes 1.8 by helical compression springs 80.

Air is drawn into the burner by the blower 9 through a downwardly directed inlet opening in a hood 94 formed on the front wall 31 of the housing 2. An air chamber 95 in the hood 94 communicates with the blower chamber l4 through a circular opening 96 formed in the front wall 31 and concentric with the shaft l2 of the blower and motor,

An air gate 91 is mounted off center on reduced diameter pin ends of adjustable pivot screws 99 which are threadedly carried in aligned holes through the side walls of the hood 94. The amount that the air gate will open under the influence of air pressure can be varied or adjusted by rotation of the rod I04 which moves the foot III to various positions. By means of the rod I04 the opening of the gate 91 which regulates the quantity of air forced through the passageway ll by the blower 9 can be adjusted while the burner is in operation to give the most efiicient and desirable type of flame in the combustion chamber 28.

The inlet end of the air passageway through the combustion air tube which is formed in the housing of the burner is of no greater cross-sectional area than the inlet end of the air tube so that air forced tangentially into the inlet end of the passageway H from the blower chamber Hi and throat i is substantially immediately given a spiral or helical path by the sloping or inclined Wall 42.

During operation of the burner, combustion air, directed tangentially into the inlet end iii of the air passageway l! by the curved wall 34 of the throat l5, moves in a curved path which develops into a spiralpath as the air travels forwardly through the tube 3. On account of the taper of the passageway H in the portion 48 of the air tube the spirally moving column of air is gradually accelerated so that its velocity is greater as it enters the head 21 than when leaving the cylindrical portion 41 of the tube.

The increased taper of the conical internal walls of the head 2'! between the shoulders 56 and 51 with respect to the taper of the portion 48 of the air tube, further accelerates the combustion air in the region of the nozzle 25 so that the maximum velocity of the.column of spirally moving air is substantially in the plane of the orifice 26 of the nozzle; Liquid fuel oil forced by the pump through the conduit 19 and pipe 2| is projected under high pressure from the orifice 26 of the nozzle 25 in the form of finely divided particles or droplets into the rapidly rotating stream or vortex of air surrounding and moving past the nozzle.

The spirally moving air column in the air tube 3 has a greater velocity at the radially outward portions thereof than at the center, and as the air enters the head 21 the radially outermost or peripheral portions of the air stream are defiected by the circumferential shoulder 56 in the passageway ll and directed to flow transversely across the helical air column in advance of the nozzle 25 to entrain particles of the sprayed fuel oil. At substantially the region of smallest crosssectional area and adjacent the extreme outlet end of the passage I! the circumferential or annular shoulder 51 deflects the outermost part of the spirally advancing air column to flow transversely across such column and entrain particles of fuel oil projected from the nozzle 25. outwardly of the burner mouth 58 the spirally moving air stream expands radially in the combustion chamber 28. The central part of the air stream is highly agitated or in a state of great turbulence effected by the cross currents influenced by the shoulders 56 and 51. and the outer portion of the air stream continues to move spirally. Fuel oil sprayed from the orifice 26 forms a'rich mixture in the highly agitated central portion of the combustion air. Combustion is initiated in this rich mixture and'is completed in the outer shell of relatively leaner mixture which is rotating in a spiral fashion. A spark plays across the tip ends of the electrodes 68 and 69 in the region of the nozzle orifice 26 substantially continuously and insures ignition of the combustible mixture in the highly agitated central portion of the air stream. If desired, the spark may be discontinued after ignition has been obtained and the burner is in operation.

The method of burning the liquid fuel carried out by the burner of the present invention is particularly successful in overcoming difficulties previously. encountered in burners which were operated intermittently, such as domestic oil burners. One such difficulty is the tendency for smoky combustion during the heating up of the firebox. Another such difficulty is the pulsating or throbbing encountered when a burner is set in operation after a period of inactivity. The cause or causes of such pulsations are not thoroughly understood but it has been found that the burner described above, operating in accordance with the method outlined, substantially overcomes the objectionable pulsating effects so that entirely satisfactory intermittent operation can be had. It is believed that the increased agitation or turbulence and the cross currents immediately in advance of the nozzle orifice, in combination with the spirally advancing air column which is accelerated in its path toward the burner head and during its passage therethrough, are instrumental in effecting the improved operation.

Other modes of utilizing the principles of the invention may be resorted to, change being made, as desired, in the particular construction and arrangement of parts shown and described, it being understood that numerous modifications'and alterations are contemplated in the method and that the disclosure of specific apparatus herein is given for purposes of explanation and illustration only.

What I claim is:

l. The method of producing and burning a combustible mixture of air and liquid fuel which comprises advancing air spirally in a generally circular sectioned column of greater length than diameter, accelerating the advancing air over the major portion of the length of the column to a deflecting zone extending circumferentially around the column intermediate the ends of the latter, deflecting a portion of the-air at said zone to flow transversely across the column toward the center thereof, accelerating the air beyond the zone at a faster rate than in advance of'the zone to another deflecting zone extending circumicrcntially around the column, deflecting a portion of the air at said last mentioned zone wersely across the column toward o1.. ,r, in finely divided particles, continuouslyancing spirally in a circular column a around and in the same direction l projected fuel, continuously intercepting and inwardly deflecting the outermost portion only of the spirally advancing air column in 2. Fr (zone extending circumferentially around the column and in advance of the orifice to flow transversely across the column toward the center thereof, continuously intercepting and inwardly deflecting another outermost portion only oily advancing air in a second zone c cii'cuniferentially around the column beyond said first zone to flow transversely the column toward the center thereof and tin and mix with the projected fuel, and

the llllllllllle.

u. 'ihe method of producing and burning a combustible mixture of air and liquid fuel which c continuously projecting the fuel from an orifice in finely divided particles, continuously rotating a mass of air in the form of a nerally circular column, continuously introair tangentially into the rotating mass end of the latter and continuously reair from the other end of the column and around and in the same general dithe projected fuel, continuously dene tangentially introduced air toward the said other end to cause the same to flow toward said other end of the column with a spiral advancing movement of the rotating mass of air, continuously inwardly deflecting the outermost portion only of the spirally advancing air in a relatively short zone extending circumferentially around the column and adjacent the plane of the orifice transversely across the column toward the path of the projected fuel and to entrain and mix with the latter, and igniting the mixture.

4. The method of producing and burning a combustible mixture of air and liquid fuel which comprises continuously projecting the fuel from an orifice in finely divided particles, continuously rotating 2. mass of air in the form of a. generally circular column, continuously introducing air tangentially into the rotating mass at one end of the latter and continuously releasing air from the other end of the column toward and around and in the same general direction as the projected fuel, continuously defleeting the tangentially introduced air toward the said other end to cause the same to flow toward said other end of the column with a spiral advancing movement of the rotating mass of air, continuously inwardly deflecting the outermost portion only of the spirally advancing air in a relatively short first zone extending cir cumferentially around the column and in advance of the plane of the orifice transversely across the column, continuously inwardly defiecting another outermost portion only of the advancing air in a second zone extending circumferentially around the column and beyond said first zone transversely across the column toward the path of the projected fuel and to entrain and mix with the latter, and igniting the mixture.

- REGINALD W. BECKE'IT.

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