US2579829A - Liquid fuel burner with oil precirculation - Google Patents

Description

Dec. 25, 1951 R JOYCE 2,579,829

LIQUID FUEL BURNER WITH OIL PRECIRCULATION Filed Jan. 6, 1950 2 SHEETSSHEET l 20 ZOa 20b FIG. I

L INVENTOR JOHN RUSKIN JOYCE BY: W/W/m HIS ATTORNEY Dec. 25, 1951 J JOYCE 2,579,829

LIQUID FUEL BURNER WITH GIL PRECIRCULATION Filed Jan. 6, 1950 2 SHEETS-SHEET 2 INVENTOR JO N RUSKIN JOY E. BY"- H IS ATTORNEY Patented Dec. 25, 1951 LIQUID FUEL BURNER WITH OIL PRECIRCULATION John Ruskin Joyce, London, England, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application January 6, 1950, Serial No. 137,063 In Great Britain January 10, 1949 16 Claims. (01.299-118) v This invention relates to liquid fuel burners it having a pressure nozzle of the type which comprises a vortex chamber fed with fuel under pressure from a fuel supply duct through a tangential swirl port or ports and having a final outlet orifice through which the fuel emerges as aspray.

' In burners of the foregoing kind it is frequently necessary or desirable to pre-circulate the liquid fuel through the body of the burner to a point adjacent to the burner tip before the burner is opened up. Thus, for example, when the burner is used to burn heavy fuel oils which are solid or semi-solid at normal temperatures, it is desirable to pre-heat the oil remaining in the burner from a previous operation before the burner is opened ,up, by precirculating heated fuel oil through the body of the burner. Again, where a combustion chamber is provided with a plurality of burners, some of which may be shut down under conditions of light load, it is advantageous to circulate cold liquid fuel through the burners so shut down in order to cool them and thus protect them from damage by heat from the flame of other burners remaining in operation. It is to be understood that the term pm-circulation," as used herein, includes circulation of liquid fuel through the body of the burner at any period when the burner is not in operation.

In the applicants copending application Ser. No. 49,732, filed September 17, 1948, a burner of the aforesaid kind is disclosed and claimed. The embodiments described therein have a burner tip provided with a vortex chamber having one or more swirl ports for admitting liquid fuel thereinto from a fuel supply duct with a rotating motion, a forward final outlet orifice, and a spill outlet for the rearward discharge of fuel into a spill return duct, and a control memher is provided to control the effective area of the swirl port or ports and of the spill of fuel through the spill duct, and wherein the control member in the zero output position thereof (corresponding to zero fiow of fuel through the outlet orifice) permits or establishes communication between the fuel supply duct and the vortex chamber for flow of fuel-through the latter and into the spill return ductadjacent to the vortex chamber. Additionally, a valve is provided close to the final outlet orifice; the valve is connected for actuation by the control member to close the outlet orifice when the control member is moved to its zero output position and to open the outlet orifice when the control member moved o chamber.

the fuel delivery positions. In the preferred and simplest form ofthis burner the aforesaid valve comprises a valve head fixed to a stem passing through the spill outlet of the vortex In the case of the smaller sizes of burner, however, this construction of the valve is somewhat diificult to manufacture with the required degree of accuracy, more especially since the stem has to be substantially smaller in diameter than the spill outlet in order that the latter shall not be unduly obstructed.

The present invention is an improvement in the burner of the aforesaid patent application which enables pre-circulation of the fuel to a point adjacent to the burner tip to be attained with a simpler and more robust form of valve. According to the present invention a liquid fuel burner having a pressure atomizing nozzle having a pre-orifice chamber, preferably of the type comprising a pre-orifice vortex chamber fed with liquid fuel under pressure from a fuel supply duct through one or more tangential swirl ports, and having a final discharge orifice through which the fuel emerges as a. spray, is provided with a pro-circulation duct communicating at one end through a pre-circulation shut-off valve with the fuel supply tank and extending forwardly, e. g., through the body of the burner, to a point adjacent to the burner tip, at which point the pre-circulation duct communicates with the fuel supply duct externally of the pre-ori'fice chamber. The burner has a tip valve adapted to shut off the final orifice from the fuel supply duct and urged by resilient means into the shut-off position. A part of the valve is subjected to the pressure of the fuel in the pre-circulation duct so that when the precirculation shut-off valve is closed the resultant increased pressure causes the tip valve to open and establish communication between the final orifice and the fuel supply duct.

When the burner is provided with a spill return duct, such duct may advantageously be constituted by a bore extending through the o'bturating end of the tip valve.

The invention will be described in detail with reference to the accompanying drawings forming a part of this specification and showing certain illustrative embodiments thereof, wherein:

Fig. 1 is a longitudinal sectional view of a burner according to the invention, the tip valve being shown in closed position;

Figs. 2 and 3 are transverse sectional views taken alon correspondingly numbered section nes on Figs. 8 and 1, respectivehl;

taken.along correspondingly numbered section lines on Fig. 1; and

Fig. 8 is a longitudinal sectional view of the rear end of the burner with the plunger and tip valve retracted, showing the opening of the spill valve.

Referring to the drawings in detail, the burner comprises a hollow cylindrical casing III in which is fitted a tubular inner body member. II which is of generally cylindrical shape. The inner wall of the casing and the outer wall of the body member have a close flt throughout the major portion of the circumference, but are so formed as to constitute, with each other, two separate longitudinal ducts l2 and I3 parallel to the axis of the burner. Thus, for example, the inner body member ll may be provided with a pair of longitudinal cut-away portions or flats at its sides and spaced diametrically as shown. Duct 12 serves as the fuel supply duct and duct l3 as the pro-circulation duct. These ducts are joined at a point adjacent'to the burner tip by a circumferential groove I4 formed in the periphery of the inner body member. The forward part of the body constitutes a nozzle portion and contains the pre-oriflce chamber I6, preferably of the vortex type. Swirl ports I5 are formed in the body member, communicating at their outer ends with the base of the groove, and inclined tangentially with respect to the wall of the chamber l6 for delivering fuel tangentially into the pre-oriflce vortex chamber IS. The pre-orifice vortex chamber is formed in any suitable manner at the forward end of the burner casing, for example, by mounting an orifice plate I! between the end of the body member II and the flange Illa at the front of the casing Ill (Fig. 4), the plate having a final outlet orifice I8 and constituting an orifice means. This platehas a cylindrical boss l9 extending rearwardly into the'bore of the body member II and presenting a, frustoconical end wall. The vortex chamber is bounded forwardly laterally bv the bore wall of the body member I l and at the rear by the tip valve, to .be described.

A generally cylindrical plunger 20, having an axial bore 20a is slidably mounted with n the bore of the inner body member I l and constitutes a disp aceable member for operating the burner.

The flt between the plunger and body memher is liquid-tight, at least at the slightly enlarged forward part 201) of the plunger, so that the forward part 20b of the plunger can close the tangential swirl ports when the plunger is in its forward position as shown in Fig. 1. In this position the said part of the plunger extends forwardly somewhat beyond the swirl ports so that these ports remain covered during the initial part of t "e rearward movement of the plunger and are mcovered only upon further retraction of the plunger. The forward end of the plunger, therefore, constitutes flow control means in the form of a slide valve for the swirl ports. The foremost end of the plunger has a cylindrical part 2| of reduced diameter which enters the vortex chamber l6 and the forward edge thereof is bevelled'to form a liquid-tight seat on the frusto-conical interior face of the orifice plate I! when the plunger is in its foremost position. The foremost part of the plunger 20,

- body member ll.

therefore. constitutes the aforesaid tip valve. *The main, elongated part of the plunger 20, al-

though shown in the illustrative embodiment to be integral with the slide valve and with the tip valve, need not be integral and performs two disl6 when the tip valve is retracted, as shown in Figs. 4 and 5 permitting excess fuel-to spill back through the plunger; when the tip valve is closed these bores are out of communication with the vortex chamber, but are still in communication with the orifice [8. The control function will be described in the next paragraph.

The rear end of the plunger 20 is enlarged at 22 and flts a correspondingly enlarged bore 23 of The flats on the sides of the body member ll commence somewhat in advance of the enlarged bore (see Fig. 6), and the ends of the ducts l2 and l 3 are in communication with the fuel supply duct 24 and the pre-circulation duct 25 within the casing (see Figs. 3 and 6) respectively. Fuel is supplied to the duct 24 under pressure from any source, not shown, and fuel is discharged from duct 25 through a shutoff valve 26 for return to a fuel reservoir (not shown). The enlarged part 22 of the plunger terminates at its forward end adjacent to the shoulder 23a formed at the junction of the smaller and larger bores of the body member H, but with a slight axial clearance when in its foremost position. This clearance constitutes a confined pressure chamber 21. Opening into this clearance or pressure chamber is a pressure port leading from one of the fuel ducts. While such port may communicate either with the fuel supply duct or the pre-circulation duct (the pres sures in these ports being almost the same). in

the embodiment illustrated the pressure port 28 is shown leading to the latter duct. The function of this port is to maintain in .the aforesaid I clearance or pressure chamber a pressure substantially equal to that in the fuel system acting against the forward, annular face of the enlarged part 22 of the plunger, for opening the tip valve in a manner to be described hereafter.

The enlarged part 22 of the plunger contains a coil compression spring 29 urging the plunger forwardly and abutting plug 30 which is threadedly secured within a well at the rear of the casing Hi, this well being a slightly enlarged continuation of the casing bore.- The enlarged part 22 of the plunger and the spring 29, to-

gether with the pressure chamber 21 and pressure part 28 constitute pressure responsive means for moving the plunger forwardly in response to a decrease in fuel pressure, and moving it rearwardly in response to an increase in said pressure. The well is closed by a threaded closure plug 3| provided with a sealing gasket 32 to render the casing oil-tight. The plug 30 also serves to retain the body member ll within the casing l0 and against the orifice plate H; for this purpose a spacer ring 33, which may be of yieldable metal to effect a semi-seal, is interposed between the rear end of the member ll and the plug. This ring has a close fit with the bore of the casing, whereby both the casing and the body member are sealed. The ring has an internal diameter small enough to permit free rearward travel of the plunger 20.

The casing H has an annular groove 34 near cates with a spill return line or spill outlet 35 provided with a throttle valve 39. Radial ports 36 in the body member II are in constant communication with the groove 34. Radial ports 31 in the enlarged part 22 of the plunger communicate with an annular groove 38 formed on the outer wall of the part 22, and the groove 38 is located for full registry with the ports 36 when the plunger is fully retracted, as shown in Fig. 8, and to be fully out of registry therewith when the plunger is in its foremost position, as shown in Fig. 1. The ports 36 and groove 38 constitute flow control means for shutting off the spill return duct when the plunger is advanced, while the valve 39 constitutes fiow control means for regulating the rate of flow through the spill return duct.

The fuel supply pipe 24, the pre-circulation pipe 25 and the spill return pipe are conveniently disposed at right angles to the burnercasing and all are grouped together at approximately the same axial position at the rear of the burner, as shown.

The burner operates as follows: Assuming the burner to be in the position shown in Fig. 1, and the valve 26 open, fuel is supplied under pressure to the supply duct 24 and flows forwardly through duct I2 and into the circumferential groove I4 in the inner body member II. The swirl ports I5 being closed by the plunger 20, all of the fuel flows back through the precirculation ducts I3 and 25 and valve 26. In this phase of the operation the fuel circulates freely. It will be understood that heated fuel will be circulated when a cold burner, containing viscous fuel, is being prepared for operation, while cold or cool fuel is usually circulated when the burner is a nonoperating member of a group of burners in the same furnace which it is desired to cool and protect from damage by heat from the flame of other burners which are in operation. In this condition of the burner the plunger 20 is urged by the spring 29 into the foremost position in which the forward part 2027 closes the swirl ports and the tip valve 2I closes the communication between outlet orifice IB and the vortex chamber I6. The axial bores flu and 20a of the tip valve and plunger, respectively, are in communication with the outlet orifice, but are shut oil from the spill return duct 35 because in this position of the plunger the groove 38 on the plunger is out of registry with the ports 36; hence, if there is any back pressure in the spill return duct 35 it will not cause dribbling of fuel through the forward end of the axial bores and through the orifice I8 communicating therewith.

When it is desired to open up the burner the pre-circulation shut-off valve 26 is closed. Pressure, transmitted through the port 28, now builds up on the forward face of the enlarged part'22 of the plunger. This pressure causes the plunger to move rearwardly against the action of the spring 29. In moving rearwardly it first opens the final outlet orifice I8 for communication with vortex chamber I 6 and thereafter uncovers the swirl ports I5, thereby opening communication from the supply duct I2 via the groove I 4 and the ports I5 to the swirl chamber. tip valve was previously opened free now of atomized fuel into the combustion chamber outside of the orifice is permitted as soon as the ports I5 are uncovered and a good spray is obtained from the start. The fully open position Since the All of the slide valve in the spill passage, (1. e., the

registry of the groove 38 with the ports) is attained at the completion of the rearward movement of the plunger, and partial communication is established even before the swirl ports I5 are uncovered, so that the return of fuel through the bores 2I a and 20a and the spill return duct 35 can take place from the start. The amount of fuel discharged through the orifice I8 may be controlled by regulation of the throttle valve 39, either with or without a regulation of the fuel pressure in the supply duct 24, as is well known in the art.

To shut down the burner and maintain precirculation the shut-off valve 26 is opened. The pressure acting on the plunger is thereupon relieved via the port 28 and duct 25 and the plunger is moved forwardly by the spring 29 to the position shown in Fig. 1, thereby first closing the swirl ports I5 to effect a sharp shut-off of the fuel flow, and preventing dribbling of fuel, which would result if the tip valve 2| were first seated. The plunger will, of course, also move to the position of Fig. 1 upon cessation of the supply of fuel through the duct 24.

I claim as my invention: a

1. A burner for liquid fuel having a nozzle portion provided with an orifice means, said nozzle having a wall structure defining a pre-orifice chamber; a fuel supply duct communicating with said pre-orifice chamber for admitting fuel into said chamber; a fuel pre-circulation duct communicating with said fuel supply duct at a point in close proximity to and externally of said chamber; flow control means between said chamber and the juncture of said ducts for controlling the admission of fuel from said supply duct into said chamber; means responsive to the pressure of fuel in one of said ducts for opening said flow control means to admit fuel from said supply duct into said chamber in response to a rise in said pressure and for closing said flow control means to prevent the admission of fuel into said chamber in response to a drop in said pressure; and means for varying the fuel pres sure in said ducts.

2. A burner for liquid fuel comprising an elongated body having a nozzle portion at the forward end thereof provided with an orifice means. said nozzle having a wall structure defining a pre-orifice chamber; a fuel supply duct extending generally longitudinally with respect to said body to a point contiguous to said pre-orifice chamber; one or more fuel admission ports connecting the fuel supply duct with the pre-orifice chamber; a fuel Dre-circulation duct extending longitudinally with respect to said body to a point contiguous to said pro-orifice chamber and communicating with said fuel supply duct at said point externally of said chamber; valve means for selectively opening or closing said fuel admission ports; a pressure responsive device connected to one of said ducts to receive pressure therefrom. having a movable element exposed to said pressure for movement in a first direction in response to an increase in said pressure; resilient means urging said movable element in a second direction opposed to said first direction; means connecting said movable element to said valve means for opening said fuel admission ports when said ele ment moves in said first direction to admit fuel from the fuel supply duct into said chamber and for closing said fuel admission ports when said element moves in said second direction to pre- I vent the admission of fuel into said chamber;

flow of fuel through said pre-circulation duct.

3. A burner for liquid fuel having a nozzle portion provided with an orifice means, said nozzle having a wall structure defining a pre-orifice vortex chamber; one or more swirl ports in said wall structure disposed substantially tangentially to the chamber for admitting fuel into the chamber to form a vortex therein; a fuel supply duct communicating with said vortex chamber through said swirl ports; a spill return duct communicating with said vortex chamber for the return therefrom of fuel; a fuel pre-circulation duct communicating with said fuel supply duct at a point in close proximity to and externally of said chamber; flow control means for regulating the flow of fuel through said swirl ports; means responsive to the pressure of fuel in one of said ducts for opening said flow control means to admit fuel from said supply duct through said swirl ports into said chamber in response to a rise in said pressure and for closing said flow control means to prevent the admission of fuel into said chamber in response to a drop in said pressure; and means for varying the fuel pressure in said ducts.

4. A burner for liquid fuel having a nozzle portion provided with an orifice means at the front end thereof, said nozzle having a wall structure defining a pre-orifice vortex chamber; one or more swirl ports in said wall structure disposed substantially tangentially to the chamber for admitting fuel into the chamber to form a vortex therein; a slide valve mounted movably with respect to said wall structure for selectively covering or uncovering said swirl ports to control the flow of fuel therethrough; a tip valve within the vortex chamber adapted to seat against said orifice means to shut ofl communication from the vortex chamber to the orifice, said tip valve being connected to said slide valve so that the tip valve is seated when the slide valve is moved in a direction to cover said swirl ports, and viceversa; a bore in said tip valve open at the front end thereof for the return of fuel from the vortex chamber when the tip valve is retracted from the orifice means: a spill return duct connected to said borein the tip valve; a fuel pro-circulation duct communicating with said fuel supply duct at a point in close proximity to and externally of said chamber; and means for actuating said slide valve and tip valve.

5. In combination with the burner according to claim 4, fiow control means for controlling the flow of fuel through said spill return duct connected for operation with said slide valve so that the spill return duct is closed when said slide valve is moved in a direction to cover said swirl ports, and vice versa.

6. The burner according to claim 4 wherein the slide valve and tip valve are so connected that the tip valve is unseated before the swirl ports are uncovered when the valves are moved in a direction opposite to the said direction.

7. A burner according to claim 4 wherein the slide valve is axially movable with respect to the wall structure of the vortex chamber and is rigidly connected to said tip valve.

8. A burner for liquid fuel having a nozzle portion provided with an orifice means, said nozzle having a wall structure defining a preorifice vortex chamber; one or more swirl ports in said wall structure disposed substantially tangentially to the chamber for admitting fuel into the chamber to form a vortex therein; a fuel supply duct communicating with said vortex chamber through said swirl ports; a swirl port valve for selectively opening or closing said swirl ports; a tip valve within the vortex chamber adapted to seat against said orifice means to shut off communication from the vortex chamber to the orifice; an axial bore in said tip .valve aligned with said orifice for communication with said orifice when the tip valve is seated and for the return of fuel from the vortex chamber when the tip valve is retracted from the orifice means; a spill return duct connected to said bore in thetip valve; a displaceable member for opening both said swirl port valve and tip valve when the displaceable member is moved in one direction and closing both said valves when the displaceable member is moved in the opposite direction; a fuel pre-circulation duct communicating with saidfu'el supply duct at a pointin close proximity to and externally of said chamber; and means for shutting off the flow of fuel in said fuel pre-circulation duct.

9. In combination with the burner according to claim 8, throttling means in said spill return duct for adjusting the flow of oil through said duct, and a shut-ofi valve connected to said displaceable member so that the spill return duct is open when said displaceable member is moved in the said direction to open the tip valve, and the spill return duct is closed when the displaceable member is moved in said other direction.

10. In combination with the burner according to claim 8, means responsive to the pressure of fuel .in said fuel supply duct and fuel pre-circulation duct for moving said displaceable member in the said direction when the said pressure increases and to move said displaceable member in the said other direction when the said pressure decreases.

11. A burner for liquid fuel having an elongated, tubular body having a vortex chamber at its forward end and an end wall with an outlet orifice; one or more swirl ports in the side wall of said vortex chamber disposed substantially tangentially to the chamber for admitting fuel into the chamber to form a vortex therein:

a fuel supply duct extending longitudinally with respect to said body and communicating at its forward end with said vortex chamber through the swirl ports; a fuel pre-circulation duct extending longitudinally with respect to said body and communicating with said fuel supply duct at said forward end externally of said vortex chamber; a reciprocable plunger within said body having a part thereof within the vortex chamber in engagement with the side wall containing said swirl ports and terminating in advance of said swirl ports, so as to cover said swirl ports when the plunger is in its forward position and to uncover said swirl ports when the plunger is retracted; a tip valve at the forward end of said plunger and within said vortex chamber aligned with said orifice and adapted to seat against said end wall to shut off communication from the vortex chamber to the orifice when the plunger is in its forward position and establish said communication when the plunger is retracted; an axial bore extending through at least the forward part of said plunger and through said tip valve aligned with said orifice for communication with said orifice when the tip valve is seated and for the return of fuel from the vortex chamber when the tip valve is retracted from the end wall; a spill return duct in communication with said axial bore; valve means for said spill return duct responsive to the position of said plunger for shutting off said spill return duct when the plunger is in its forward position and for opening the spill return duct when the plunger is re-' and means for reciprocating said pressure; and a valve in the pre-circulation duct for shutting off the flow of fuel therethrough.

13. A burner for liquid fuel having an elongated tubular body having a confined vortex chamber at its forward end and an end wall with an outlet orifice; an annular groove in said body surrounding said swirl chamber and separated by an annular wall from said swirl chamber; one or more swirl ports in said annular wall communicating at their outer ends with said groove and having their inner ends disposed substantially tangentially to the chamber for admitting fuel into the chamber to form a vortex therein; a fuel supply duct communicating with said annular groove; a fuel pre-circulation duct communicating with said groove at a pointspaced from said fuel supply duct, whereby fuel supplied through the fuel supply duct must flow through said annular groove before entering said precirculation duct; and valve means within the vortex chamber for covering and uncovering said swirl ports.

14. In combination with the burner according to claim 13, a spill return duct within said body communicating with the rear of said vortex chamber. 7

15. In combination with the burner according to claim 13, a tip valve within the vortex chamber adapted to close the outlet orifice having a control plunger extending rearwardly from the vortex chamber, and bore with said plunger forming a spill return duct communicating with said vortex chamber.

16. A burner for liquid fuel having an elonnear the forward end thereof and communicating with said fuel supply duct; one or more swirl ports between said groove'and the swirl chamber disposed substantially tangentially thereto for admitting fuel into the chamber to form a vortex therein; a longitudinal fuel pre-circulation duct within said casing communicating at its forward end with said groove; a pressure port connecting one of said ducts to the enlarged rear part of the bore of the body member; a reciprocable plunger within the bore of said body member having a hollow enlarged rear part within said enlarged rearpart of the bore of the body member and extending forwardly into the vortex chamber, said enlarged rear part of the plunger presenting a forwardly directed face exposed to fuel pressure transmitted through said pressure port, at least the part of the plunger within the vortex chamber having a close fit with the chamber wall, said part of the plunger terminating in advance of said swirl ports, so as to cover said swirl ports when the plunger is in its forward position and to uncover said swirl ports when the plunger is retracted; a tip valve at the forward end of said plunger and within said vortex chamber aligned with said oriflea and adapted to seat against said end wall to shut off communication from the vortex chamber to the orifice when the plunger is in its forward position and establish said communication when the plunger is retracted; an axial bore extending through the plunger from said hollow enlarged rear part through said tip valve aligned with said orifice for communication with said orifice when the tip valve is seated and for the return of fuel from the vortex chamber when the tip valve is retracted from the end wall; resilient means urging said plunger forwardly in opposition to the full pressure acting on said forwardly directed wall of the plunger; a spill return port through the body member at said enlarged rear part thereof; a port in said hollow enlarged rear part of the plunger positioned for registry with said spill return port when the plunger is retracted and for displacement out of registry therevith when the plunger is in its forward position; ,nd means for shutting off the fuel pre-circulation duct at a point beyond said pressure port.

JOHN RUSKIN JOYCE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Num er Name Date 1,252,254 Fisher Jan. 1, 1918 2,015,611 Wettstein Sept. 24, 1935 2,079,430 Bargeboer May 4, 1937 2,345,402 Lubbock et a1 Mar. 28, 1944

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