Title:
Liquid fuel burner
United States Patent 2306141


Abstract:
This invention relates to the construction and operation of liquid fuel burners, and more particularly, to liquid fuel burners adapted for efficient operation over a wide range of fuel output and in which the liquid fuel may be atomized either mechanically or by means of a gaseous atomizing fluid.



Inventors:
Richardson, Andrew R. W.
Application Number:
US28635739A
Publication Date:
12/22/1942
Filing Date:
07/25/1939
Assignee:
BABCOCK & WILCOX CO
Primary Class:
Other Classes:
239/11, 239/404, 239/466, 239/496
International Classes:
F23D11/24
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Description:

This invention relates to the construction and operation of liquid fuel burners, and more particularly, to liquid fuel burners adapted for efficient operation over a wide range of fuel output and in which the liquid fuel may be atomized either mechanically or by means of a gaseous atomizing fluid.

One of the main objects of my invention is to provide a method of firing by liquid fuel in.which liquid fuel is delivered to the whirl chamber of a liquid fuel burner in such a manner as to cause a whirling and axial movement of the fuel therein towards a restricted discharge orifice, a gaseous atomizing fluid is delivered to the whirl chamber in the neighborhood of the fuel discharge orifice in such a direction as to cause it to whirl therein in the same direction as and in contact with the liquid fuel, and the pressure at which liquid fuel is supplied to the burner is adjustable for the purpose of regulating the output of the fuel burner.

A further object is to provide in a liquid fuel burner having a whirl chamber with a restricted discharge orifice at one end, ducts for directing liquid fuel and a gaseous atomizing fluid respectively into the whirl chamber and so located and directed as to cause both the liquid fuel and the atomizing fluid to whirl in the chamber in the same angular direction.

A further and more specific object is to provide a simple and effective control mechanism for a liquid fuel burner of the character described by which the amount and pressure of the liquid fuel supplied is regulated in accordance with operating conditions and the supply of 3 atomizing fluid regulated in accordance with the atomization needs of the fuel burner as determined by the pressure of the liquid fuel supplied.

The various features of novelty which characterize my invention are pointed out with particu- 4 larity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying draw- 4 ings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawings: Fig. 1 is a sectional elevation of a liquid fuel burner constructed in accordance with my invention; Fig. 2 is a front or furnace end view on an enlarged scale of the slot or sprayer plate shown in Fig. 1; 5 Fig. 3 is an enlarged sectional elevation of the diaphragm member shown in Fig. 1; Fig. 4 is a front or furnace end view of the diaphragm shown in Fig. 3; Fig. 5 is a diagram of the system of supply connections to the fuel burner; and Fig. 6 is a graph illustrating the range of fuel burner output capacity available with apparatus constructed according to the invention.

As illustrated in Figs. 1-4, the liquid fuel burner has an annular liquid fuel channel I surrounding a gaseous atomizing fluid channel 2, the channels being formed by outer and inner concentric tubes 3 and 4 respectively. Each of the channels communicates with a cylindrical unobstructed whirl chamber at the furnace end of the fuel burner. The channel I communicates with the whirl chamber through inwardly Inclined or obliquely converging ducts or passages 6 in a diaphragm member 15 which extend from the end of the channel I and open through the end wall of the whirl chamber 5 within a relatively small radius. The atomizing fluid channel 2 also communicates with the whirl chamber 5 through outwardly inclined or diverging passages 7 in the diaphragm member 15, having their discharge ends opening into an annular groove 33 in the front or furnace face of the diaphragm member, which groove in turn '0 registers with an annular groove 8 in the outer or rear face of a slot or sprayer plate 14 defining the circular sides of the whirl chamber. The groove 8 communicates through holes 9 with an annular groove 10 in the front face of the " sprayer plate. A plurality of ducts or slots 1 extend from the groove 10 along the front face of the plate 14 and open tangentially into the whirl chamber 5 at symmetrically spaced points adjacent Its forward end. On account of the 0 skew disposition of the ducts 6 and the tangential disposition of the slots 1 with respect to the whirl chamber 5, both the gaseous atomizing fluid, such as steam, which may be supplied to 5 the channel I and the liquid fuel which may be supplied to the channel 2 will pass into the whirl chamber and rotate therein in the same angular direction before issuing from the restricted discharge orifice 12 at the end of a tapered exten0 sion of the whirf chamber in an orifice or nozzle plate 13 arranged at the front side of the sprayer plate, as a diverging atomized spray. The orifice plate 13, slot plate 14, and diaphragm 15, are held in assembled position on the front end of 5 the tube 3 by a cap screw 16. The end of the inner tube 4 is held in a concentric position by a cylindrical extension of the diaphragm II.

The outer ends of the tubes 3 and 4 are screwed into a removable body member 11 of the burner coupling which is removably held in contact with a fixed part 18 by a pivoted yoke II and screw 18b, whereby the corresponding liquid fuel and atomizing fluid passages therein are maintained in communication.

A non-return valve 21 is arranged in the steam i1 flow pa through th t te coupling part I and is adapted to prevent any return flow of liquid fuel through the steam passages of the burner by seating on a valve seat 28 formed in the end of the valve body 19. The valve stem is maintained 1 concentric with the valve seat by arms 29 connecting a central internally threaded sleeve 30, into, which the valve stem is screwed, with a sleeve member 31 slidable in the valve body I9, and provided with a radial flange 32 which lrm- 2 its the upward opening movement of the valve stem. The valve body IS is screwed into the steam passages to the coupling part II and is itself provided with coupling means for connection with the steam supply. When the pressure 2 difference on opposite sides of the valve 21 is insufficient to maintain it open against the tendency of gravity to close it, it will close and preclude pny possibility of liquid fuel from the whirl chamber backing up into the steam supply 3 line.

In the burner supply system diagrammatically illustrated in Fig. 5, the liquid fuel is withdrawn from a fuel tank 101 and, after flowing through the line 102 past the stop valves 103 and 104 and filter 105, is delivered by a positive displacement pump 106 driven by a constant speed electric motor to the supply line 101 after being heated by an oil heater 108. The quantity of oil delivered by the pump 106 is arranged to correspond to the quantity consumed by the burner at the maximum rating of the burner. From the line 101 the oil passes to the burner 109 through a shut-off valve 110 and in a regulable amount to the oil return line III through which it returns to the tank 101, control of the amount returned and consequently control of the burner output being effected by a control valve 112 in the return line.

Steam from any suitable source is supplied through the line I I and after passing through a stop valve 114, a reducing valve 11, and a shutoff valve 116 is delivered to the burner it9. In one particular embodiment steam is supplied to the burner at a constant pressure of about 20 to 50 lbs. per sq. in. and a valve disposed between the pump and the burner is adapted to vary the pressure of fuel oil at the burner between the limits of about 5 lbs. per sq. in. and 200 lbs. per sq. in., perfect atomization being obtained throughout this range. The most suitable steam pressure depends upon the nature of the oil and can be readily determined by test.

The burner control system also includes an oil pressure gauge Il a steam pressure gauge II118, a steam line drain 119, an oil tank vent 1.20 and a branch steam line 121 for preliminary heating of the oil withdrawn from the tank beneath a hood 122.The graph of Fig. 6 illustrates a wide range of burner output extending from 10 lbs. of oil per hour to 650 lbs. per hour with perfect atomizat.on throughout the range, obtained by varying the oil pressure at the burner between 5 lbs. per sq. in. and 200 lbs. per sq. in. simply by operation of the valve 112 and without changing nozzles or making any other adjustment. The steam pressure at the burner was automatically maintained constant by the reducing valve 115 at 45 lbs. per sq. in. The non-return valve 21 in the steam conduit automatically closed when the oil pressure was about 85 lbs. per sq. in., so that over the higher part of the.range the fuel was atomized by mechanical atomization only.

0 The amount of steam required to effect atomization even at the lowest burner output is small and as the output increases the back pressure which builds up in the whirl chamber effects a progressive decrease in the steam consumption. The apparatus therefore is highly advantageous not only from the points of view of ease of control and excellence of atomization over a particularly wide range, but also from the point of view of economy in operation. Moreover, the low 0 pressure and small quantity -of the steam or other gaseous atomizing fluid used results in silent operation.

Should the back pressure in the whirl chamber be insufficient to result in the closing of the non5 return valve 27 at- the lowest oil pressure at which the steam can be dispensed with while still obtaining perfect atomization, the shut-off valve 116 may be closed by hand or a further valve may be provided which closes automatically in [0 dependence on the oil pressure when the said lowest pressure is attained.

Air may also be used as the gaseous atomizing fluid, the steam supply and reducing valve being replaced by means for supplying air at low 5 pressure to the burner. The air supply may be one which also serves some other purpose, or it may be especially for the burner. The air supply may be provided with suitable pressure regulating means.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of the invention now known to me, those skilled in the art will understand that changes may bemade in the form of the appa45 ratus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

50 I claim: 1, A method of operating a liquid fuel burner having a restricted discharge orifice at one end of a whirl chamber which comprises delivering liquid fuel under pressure to the whirl chamber 05 at points in the end thereof remote from the discharge orifice and with axial and angular components of motion towards the discharge orifice, delivering a gaseous atomizing fluid tangentially to the whirl chamber at a point in the neighborhood of the orifice and in a direction causing it to whirl: n the chamber in the same direction as the liquid fuel, maintaining the pressure of the gaseous atomizing fluid substantially constant, adjusting the pressure at which the liquid ,5 fuel is supplied to the burner to regulate the output of the burner, and cutting off the supply of atomizing fluid when the liquid fuel pressure exceeds the atomizing fluid pressure by a predetermined pressure differential.

70 2. A liquid fuel burner having a cylindrical whirl chamber with a tapered extension terminating in a restricted discharge orifice, means for supplying liquid fuel to said whirl chamber including an annular supply passage and a dia75 phragm member having symmetrically arranged converging passages opening through the sidi thereof forming the wall of said whirl chambe: at the end remote from said orifice and in a di. rection causing a whirling of the liquid fuel whilc moving therein towards said orifice, dnd means for supplying a gaseous atomizing fluid tangentially to said whirl chamber at points adjacent said orifice and in a direction causing a whirling thereof in the same direction as and in contact with the liquid fuel, said last named means including an atomizing fluid supply passage within said annular liquid fuel supply passage.

3. A liquid fuel burner having a cylindrical whirl chamber with a tapered extension terminating in a restricted discharge orifice, means for supplying liquid fuel to said whirl chamber including an annular supply passage and a diaphragm member having symmetrically arranged converging passages opening through the side thereof into said whirl chamber at the end remote from said orifice and in a direction causing a whirling of the liquid fuel while moving therein towards said orifice, and means for supplying a gaseous atomizing fluid to said whirl chamber including a supply passage within said liquid fuel supply passage, diverging passages in said diaphragm member, and a slot plate having slots therein arranged tangentially to said whirl chamber at points adjacent said orifice and in a direction causing a whirling thereof in the same direction as and in contact with the liquid fuel.

4. A control system for liquid fuel burners comprising a liquid fuel burner having a whirl chamber terminating in a restricted discharge orifice, means for supplying liquid fuel under pressure to said whirl chamber in a direction causing a whirling of the liquid fuel while moving towards said orifice, means for supplying a gaseous atomizing fluid tangentially to said whirl chamber and in a direction causing a whirling thereof in the same direction as, the liquid fuel, means for maintaining the pressure of the atomizing fluid substantially constant, means for regulating the pressure of the liquid fuel supplied, and ; valve means responsive to said liquid fuel and 3 atomizing fluid pressures for cutting off the sup-' r ply of atomizing fluid when the liquid fuel pres- sure exceeds the atomizing fluid pressure by a e predetermined value.

s 5. A control system for liquid fuel burners comprising a liquid fuel burner having a whirl chamber terminating in a restricted discharge S orifice, means for supplying liquid fuel under pressure to said whirl chamber at the end thereof remote from said orifice and in a direction causing a whirling of the liquid fuel while moving towards said orifice, means for supplying a gaseous atomizing fluid tangentially to said whirl chamber at a point adjacent said orifice and in a direction causing a whirling thereof in the same direction as the liquid fuel, means for maintaining the pressure of the atomizing fluid substantially constant, means for regulating the pressure of the liquid fuel supplied, and valve means in said atomizing fluid supply means and responsive to said liquid fuel and atomizing fluid pressures for automatically cutting off the supply of atomizing fluid when the liquid fuel pressure exceeds the atomizing fluid pressure by a predetermined amount.

6. A liquid fuel burner having a cylindrical whirl chamber with a tapered extension terminating in a restricted discharge orifice, means for supplying liquid fuel to said whirl chamber including an annular supply passage and a diaphragm member having symmetrically arranged converging passages opening through the end wall of said whirl chamber remote from said orifice and in a direction causing a whirling of the 33 liquid fuel while moving therein towards said orifice, and means for supplying a gaseous atomizing fluid to said whirl chamber including a supply passage within said liquid fuel supply passage and diverging passages from said atomizing 10 fluid supply passage having their discharge ends connected tangentially to said whirl chamber at points adjacent said orifice and in a direction causing a whirling thereof in the same direction Sas and in contact with the liquid fuel.

ANDREW R. W. RICHARDSON.