US2030124A - Method for burning liquid fuels - Google Patents

Description

1936- I H. A. TIFFANY 2,030,124 METHOD FOR BURNINQ LIQUID FUELS J Original Filed April 17, 1929 Z8 4 28 v gym/MM Patented Feb. ll, 1936 2,030,124

UNITED STATES PATENT OFFICE" METHOD FOR FUELS I I Original application April 17, .1929, Serial No. 355,688. Divided and this application March 11, 1935, Serial No.'10,54 4

Claims. (ci.15s -117.5) I

The present invention relates to methods for them, thereby facilitating the downward and rabuming liquid fuels such as oil, and particularly dial movement of the hot burned out products of to a method of liquid fuel combustion to be carcombustion so that the latter are mixed with and 'ried out in a furnace having a boiler wall or the substantially envelop the streams of oil spray. like to be efiectively heated. Preferably the streams are provided through ro- &

The present application is a division of my tating spouts'the outlets of which are radially copending application Serial No. 355,688, filed distant from the rotational axis substantially as April 17, 1929, which discloses fuel burningapfar or farther than the periphery of the rotating paratus of the type in which a fire box is closed head and, preferably also, farther than the tips at the bottom by a hearth above which projects of the fan blades whi a p y d to ta h m a motor-driven head for projecting fuel and'air. the outward draft of a thin layer of air between More particularly, said copending application disa the upper surface of the hearth and the oilspray. closes and claims an improved type of such ap- Preferably the spouts project above the level of paratus, in which the hearth and head are dethe top surface of the head or are otherwise assosigned and operated so that a remote or periphciated therewith so that there are spaces between 15 eral flame wall functions as the real burner at them facilitating inflow of hot products of comwhich combustion is initiated; the head being bust on, and so that their p oje t su ces specially designed and operated so as'to prevent function to a noticeable extent as fans tending the fuel and air from igniting until-impact with to centrifugally project said products of combussaid flame wall, a characteristic of this type of tion. go head and hearth being that th flam th i l- Among other features of specific contributory tiated at the wall may be as diffused, and comimportance which may be employed in a prebustion as perfect, as may be desired. ferred head for practicing the invention is that The present invention concerns an improved of having the peripheral-orifices for the promethod of combustion adapted for use in many jected oil arranged so that when the head is 5 furnaces, but primarily perfected for use in conrotated, the leading edge of each orifice projects nection with hearths and ignition walls of the farther from the axis than does its trailing edge. general type disclosed in the Heath Patents No, Preferably, a radial draft of is discharged 1,886,675, granted November 8, 1932, and No. beneath the oil streams across the upper surface 1,979,465, granted November 6, 1934, Both show of the hearth; In practice, the slope of the 3 and describe the preferred fuel and air projector. hearth, the speed of rotation of the head and that I use for practicing my improved method, the distance between the head and theflame wall while specificallyacknowledging me as the inven are so proportioned that the hearth surface partor of the novel features thereof. allels the oil trajectory nearly enough to prevent In burning oil in accordance with this new substantial amounts of oil from impact, air- 35 method, the rotary head is driven at relatively ixing andbu n except on and adjacent the constant low speed, say 1700 to 1750 R. P. M. reflame wall. It may be desirable to have the gardless of the amount of fuel that is being upper surface of'the hearth slope downwardly burned: combustion is prevented until impact, from the central head to the peripheral flame 40 and is made certain of initiation upon impact wall so as to more closely parallel the falling 40 r with dependence upon the relations as well as trajectory of the oil for a greater distance. the proportions of oil, air, and burned out prod- In the preferred form of apparatus for carryucts of combustion in the projected draft; and ing out mymechanical method, the head receives the objects ofv my invention include producing a air from below the'hearth, the supply being pref- Y 4 projection method under'which the oil, air, and erably regulated by a valve controlling the air products of combustion are projected in more intake-opening. The low pressure condition properfect relation for insuring the desired results, duced in the head is the resultant of stack draft under widely-varyingconditions of fire box sizes and the centrifugal effects of the fan and of the and the amount or range of oil feed. Important spouts uponthe air in each. The centrifugal features of my invention, each of which are novel effects of the head cause a considerable amount 50 and-all of which cooperate to produce the desired of hot burned out gases, mainly nitrogen and results include the following: i carbon dioxide, to be admixed with air and fuel The oil is projected outwardly, in a plurality oflayers projected from the head and thus assist individual streams. Preferably the streams are in preventing combustion before the layers reach few in number to afford wide spaces between the flame wall. The hot burned out gas is furtemperature and to lessen the skin tension and prevent over-sized oil globules or particles from being projected from the spouts.

globules to follow the desired, definite path of projection. The burned out gas, being rich in carbon dioxide has the further well known effect oiidiluting the air draft, prolonging and diffusing the combustion and, consequently, promoting complete combustion at the flame wall.

The invention may be more fully understood from the following description in connection with the accompanying drawing, wherein:

Figure 1 is a fragmentary vertical sectional view through the hearth of a boiler showing a preferred form of projector head in an operative position for carryingout the method of the pres'- ent invention;

Figure 2 is an enlarged top plan'view of-the same head with parts broken away and in section for the sake of clarity;

Figure 3 is a transverse sectional view on the irregular line 3-3 of Figure 2; r

Figure 4 is a side elevational or edge view of the head; and

Figure 5 is a sectional detail showing the manner in which steel wool packing may be arranged in the spouts.

The method of this invention can best be ex plained by first describing the above mentioned apparatus, as follows:

The hearth I0 is generally similar to the hearth disclosed in the prior Heath patents above idenoutwardly turned flange l5a of hollow, generally frusto-conical air collar IS, the latter being supported inany suitable way, of which there are several now well known; Member 16 preferably forms a liner for the central opening in the hearth, being provided at its upper edge with an inwardly and downwardly turned flange I8.

The oil projector'head preferably comprises a sand casting including a generally cylindrical body portion 20, the top 2| of which is closed over save for central opening 22. The lower edge of the body is formed with an inwardly projecting annular flange 23 terminatlng'in upturned lip 24, the lip, flange and body wall forming a relatively shallow annular trough 25 into which the oil to be projected is-delivered. Externally the body '20 is formed with an upwardly inclined external flange 26 which divides the body into an upper oil projector portion and a lower fan portion. v

The fan includes a plurality of blades 21 below and integral with the flange 26 and the oil projector portion includes a plurality of spouts or conduits 28 integral with and above theflange for discharging individual streams of oil.

These projectors are of generally tapering formation, their inner ends being of general rectangular shape, as best seen in Figure 3, and their outer ports or orifice being substantially cir-' cular. The projectors preferably inclined slightly upwardly, this inclination being generally in the plane of the flange 26. It willbenoted that they alsoproject above the flange so that their The decrease in skin tension will obviously further cause the blades to accelerate recirculation of the hot burned out gases and to project them outwardly with the oil and air. The trailing edges or sides of the projectors are disposed approximately radially of the head and the leading edges of. the projectors are disposed approximately tangentially of the body 20' and project somewhat farther beyond the periphery of the flange than do the trailing edges, tending in this manner to create a slight suction at the outlet ports or orifices of the projector. The important result of having the trailing walls of the projectors disposed in a general radial plane is that the oil should be positively centrifugally flung or impelled from the 'orificesof the projector spouts and not be permitted to simply leak out of them, as might be the case were the trailing edges disposed at the same radial distance from the axis The head is mounted within the central opening of the hearth defined by the air collar IS with the lower outer edges of the fan blades just clearing the inner upper edge of the collar. The air draft upwardly through the collar I6 is controlled by a. vertical adjustable damper collar 3|! which may be raised from the position of Figure 1 to restrict the size of the annular air inlet opening as desired.

The head is mounted upon the upper end of a vertical shaft 3| driven from any suitable power source such as an electric motor as is now common in this art. Oil supply pipe 32 extending upwardly into the head carries a laterally extending oil spout 33 which overhangs the trough 25 and delivers oil into the trough.

The overhang of the spout 33 presents a slight problem in assembling the head which is taken care of by the provisionof an opening 22, of considerably larger diameter than the motor shaft 3| and of slightly smaller diameter than the fixed driving collar 34 of the motor shaft, a pin 34a to fit the opening 34b (see Fig. 2) in the head and a nut 35' which coacts with the collar to clamp the head in position. The upper end of the motor shaft is threaded at 36 for the reception of the collar and nut. This oversize opening 22 permits the head to be dropped down over the threaded end of the motor shaft, moved laterally until the trough is clear of the spout 33 and then brought back to center and clamped by screwing home the nut 35.

The sand casting of the'head affords a very material advantage in operation under some conditions. The minute proturberances on the rough internal surfaces of the casting are wetted by the oil, thereby increasing the area of contact of the oil with the heated metal surface. Another effect is to retard and distribute the oil film more uniformly, this being of advantage in rendering the resulting spray more'uniform, particularly when relatively large amounts of oil are being discharged. This, however is not always essential.

In operation, when the head is set in motion and the oil feed turned on, the oil collecting in the bottom of the trough 25 will form, under the action of centrifugal force, a film which gradually creeps up the. interior of the wall 20 and as it reaches the spouts flows outwardly through them,

and is centrifugally' thrown with considerable force and in a fairly straight trajectory toward the flame wall II, this oil, when the motor is running at its normal speed, tending toimpinge upon the flame wall without deposition on the hearth at points between the projector and the wall.

The air draft on the other hand is projected radially from the fan blades 21, the air trajectory,

being below the oil trajectory so that there is only partial admixture of the oil and air except in the immediate neighborhood of the flame wall.

constitute a large volume fan drawing air through the variable passage B, (Fig. 5), between the stationary collar 16 and the upwardly adjustable collar 30. In normal operation, this passage 'is sufliciently restricted to tend to create a vacuum in the interior space A. The four nozzles 28 constitute another fan tending to create suction within the head, and, through annular passage D,.

this suction tends to take effect in the same space that the fan blades 21 draw from. Thus, the many blades 21 and thefour nozzles 28 constitute two fans connected in parallel to the same source. When the main air supply is unrestricted there may be a small amount of air delivered through nozzles 28, but this. amount is much smaller'than that delivered through blades 21, because the flow section through passage D and the four little nozzles is very much less than that of the annulus through which blades 21 discharge.

It will be seen that by adjusting collar 30 to appreciably restrict the air inlet to the chamber A, the fan blades 21 may actually recirculate some of the hot combustion gases by drawing them through the nozzles 28 in opposite direction to the flow of outgoing oil. This recirculation, however, can do no harm and under certain conditions it is of advantage to have combustion gases mixed with the primary air to produce a low blue flame of very high efficiency. f

In operation, oil is supplied to the trough 25 through the interior nozzle 33. Centrifugal force causes a film of this oil from trough 25 to creep up the walls and ultimately, to be thrown oil as a spray projected from the rear lips of the four nozzles 28. Centrifugal force may also cause a relatively small volume of air to be projected through the nozzles 28 as above explained, while a much larger volume of air is being projected by the fan blades 21. The nozzles 28 project substantially above the plane of the top plate 2| of the rotor. Consequently said plate, together with the upwardly projecting surfaces of the nozzles, constitute in effect another fan whereby hot products of combustion are projected in the same horizontal plane with the oil spray. Thus the.

composite draft produced by the nozzles consists of a non-combustible mixture of hot products of combustion, oil spray, and possibly a small percentage of air. When this composite mixture Strikes the periphery of the hearth, the oil spray is further atomized, and mixed with the air from the fan blades. This final mixture easily ignites at starting, and when the apparatus is in full operation so that the refractory impact surfaces-are at high temperature, substantially'perfect combustion begins and is maintained entirely at the p p ery.

The factors which control they blueness or ethciency of the flame ring which impinges almost directly on the cold water leg of the boiler are of course the correct admixture of air and ofl which is determined to a large extent by the extent of volatilization and atomization of the oil when the latter reaches the combustion wall. By proper metering of the air and the oil this mixture will be substantially the same at the periphery of a 1'7" hearth or of a 56" hearth, since while the additional oil flow necessary for the larger hearth results in the oil being projected from the head in larger particles, the added dis tance through which the oil must travel and in which it .is subjected to the heat of the fire box increases volatilization to suchan extent that there is no appreciable difference in the efficiency of the mixture.

It is not only possible but desirable in' certain instances to promote a substantial atomization of oil in or at the head, and this may be readily accomplished by the introduction of small wads of steel wool such as 353: shown in Figure 5 in the oil nozzles. These steel wool wads are rather loosely packed and the wool is of fairly coarse grade, the wads being held against flying out centrifugally by the pins 36$.

The invention may be embodied in other spe cific forms without departing fromthe spirit or essential characteristics thereof. The present embodiment is'therefore to .be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:-

1. A method of effecting combustion of liquid fuel, said method consisting in flinging a fuel spray in non-combustible form in a general radial directiontoward an outward zone of combustion, simultaneously directing a supply of air along a path closely paralleling that of said fuel spray but without substantial admixture with the latter, simultaneously directing a quantity of gases of combustion along the path of said fuel spray to assist in preventing the air stream fromcommingling with the fuel spray to form a combustible mixture, and merging the air stream and the fuel spray for combustion in the region of said outward zone.

2..The method of effecting combustion in a chamber having a surface to be heated, which comprises impinging individual liquid fuel streams against said surface; passing a stream of air in the general direction of the fuel streams toward said surface in sufficient quantity to support combustion of the fuel streams; mixing said air and fuel streams substantially solely closely adjacent the locus -of fuel impingement on said surface; and burning 'the mixture at said surface.

3. In a method of liquid fuel combustion the steps of projecting from a liquid fuel source a plurality of separate non-combustible'sprays includstantial admixture with the latter in the interj steps of flinging from a liquid fuel source a plumediate zone so that'air is mixed with the spray substantially solely in the region of said surface and where-combustion takes place.

4. A method of effecting liquid fuel combustion consisting of the steps of projecting liquid fuel spray in multiple jets substantially'horizontally through space and entirely without interference toward a relatively remote upright surface, without suflicient air for combustion and with suflicient velocity to carry said jets into impingement with said surface; and supplying air for combustion under forced draft into intersection with the projected jets only in the zone of impingement to thus form a combustible mixture; and burning said combustible mixture in said zone. a

5. In a method of liquid fuel combustion, the

rality of separate non-combustible sprays including liquid fuel toward a. surface that is relatively remote from said fuel source and separated therefrom by an intermediate zone of non-combustible spray travel; and simultaneously directing a flow of air along a path closely paralleling said non-combustible sprays but without substantial admixture with the latter in the intermediate .zone so that air is mixed with the spray substantially solely in the region of said surface and where combustion takes place; and simultaneously directing a quantity of gases of combustion along the paths of said fuel sprays to assist in preventing the directed air-from commingllng with thefuel sprays to form a combustible mixture prior to reaching said surface,

HOMER A. TIFFANY.

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