US2690795A - Fuel oil burner and controlling apparatus - Google Patents

Description

Oct. 5, 1954 Filed Nov. 24, 1950 H. w. B. WEBB 2,690,795

FUEL OIL BURNER AND CONTROLLING APPARATUS 5 Sheets-Sheet 1 I N van/Ton HOWARD W B. WEBB M' WW Oct. 5, 1954 H. w. B. WEBB 2,690,795

FUEL OIL BURNER AND CONTROLLING APPARATUS Filed Nov. 24, 1950 3 Sheets-Sheet 2 INVENTOR Huh/ARI) M W Oct. 5, 1954 H w, WEBB 2,690,795

FUEL OIL BURNER AND CONTROLLING APPARATUS Filed Nov. 24, 1950 s Sheets-Sheet s as 38G. 38

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vw WgfW/l/M IN VENTOR 53 HOWARD M B. WEBB Patented Oct. 5, 1954 OFFICE FUEL OILBURNER AND CONTROLLING APPARATUS .Howard William Barrett Webb, Glen Iris,

Victoria, Australia.

Application November 24, 1950, Serial No. 197,313

Claims priority, application Australia December 5, 1949 4 Claims.

on relatively heavy fuel oil, known as furnace or bunker oil, have been designed and constructed with a view to operating with such oil under high pressure, and the burners have generally been of the full on-full off type i. e. they are not suitable for intermediate adjustment of the rate of burning from one extreme to the other.

On the other hand, burners capable of a variation of the intensity of burning, commonly known as modulating burners, have generally been of a self contained type, that is to say, automatic modulating control mechanism for the burner has been incorporated with the body of the burner itself and, even when operating on a lighter type of fuel oil, such burners-exhibit a decided tendency to gum up and get out of order with frequent need for servicing. If a heavier type of fuel oil should beused the mechanism is subject to frequent gumming up and even more frequent attention is necessary.

Furthermore, whilst some automatic fuel burners of the modulating type have utilized an air operated piston as motive power to control the actual burner, they have used individual and separate methods of controlling or throttling the supply of air to the burner.

It is an object of the present invention to devise a modulating fuel oil burner eminently suitable for use with a relatively low grade of fuel oil, further characterized in that the oil burner itself is devoid of any parts which are likely to give trouble when operating on a lower grade of oil and yet at the same time will operate at a maximum efficiency. In this connection, it is proposed that automatic modulating mechanism for use in conjunction with the improved burner be provided as a unit separate from the actual burner itself, thereby not being subject to troubles so common with self contained modulating burners as hereinbefore mentioned.

It is another object to devise an automatic modulating or control means whereby a single air operated piston serves the dual purposeof providing the motive power for the control of oil to the burner and also as a valve for controlling the main supply of air to the burner.

I propose a fuel oil burner capable of a variation in theintensity of burning wherein air is adapted to issue from the outlet of a pilot air chamber surrounding an oil supply and atomizing nozzle towards a combustion chamber, and wherein a main supply of air under pressure is introduced independently and concentrically through an air register forwardly of the pilot air outlet towards the combustion chamber to thereby assist in atomizing of the oil without passing over or contacting the oil atomizing nozzle.

A preferred fuel oil burner in accordance with this invention may comprise an oil atomising nozzle adapted to be supplied with fuel oil and extending centrally to adjacent the outlet port of a pilot air chamber adapted to be supplied with air under pressure, an outer chamber surrounding the pilot air chamber and provided with an annular outlet concentric with the outlet port of the pilot air chamber for direction towards a combustion chamber, and an annular chamber mounted forwardly of the pilot air chamber and outer chamber and arranged to direct air independently under pressurethrough an air register into a combustion chamber, the outer chamber an annular chamber being supplied with air under pressure from a common source which may be subject to control.

The following description and accompanying drawings relate to a practical arrangement of the improved fuel oil burner and controlling apparatus therefor, but it is to be understood that various alterations and/or additions may be incorporated without departing from the spirit and scope of the invention.

Referring to the drawings which form part of this specification:

Figure l is a semi-diagrammatic and sectional view showing the invention applied to a steam generator.

Figure 2 is a detailed sectional view of the improved burner, mounted on the generator casmg.

Figure 3 is a reduced sectional view on line IIIIII of Figure 2.

Figure 4 is a part sectional view of associated control mechanism.

Figure 5 is a sectional view of an oil control valve shown in Figure 4.

Referring to Figure 1, the arrangement may be said to comprisean improved oil burner B, a source of high pressure air supply AS, which may be from a blower-fan F driven by an electric motor EM modulating mechanism M for controlling the main supply of air to the burner and also adapted to control the amount of oil which may flow to the burner, a by-pass conduit BC from the source of air supply to direct air under pressure to a pilot air inlet on the burner, and conduits or means for conveying the air under pressure (subject to control as aforesaid) to the annular chamber and air register portions of the burner and to the outer chamber portion thereof.

Referring to Figure 2, the oil burner includes an oil atomizing nozzle 5, mounted on the forward end of a tubular member 2, the remote end 2a of which is carried on the back of the burner casing, and is provided with means for connecting a conduit (3 in Figure l) for conveying oil to the nozzle from an oil control valve V.

The tubular member 22, carrying the atomizing nozzle projects axially through an annular pilot air chamber l, at the forward end of which, and concentric with the atomizing, nozzle is an inner tapered. outlet tube 5 having as an inner pilot air exit port Ea, with a relatively larger outlet tube .1 concentric with the inner tube and forming an outer pilot air exit port la. Air from the source of high pressure air supply is conveyed by conduit BC to the annular pilot air chamber t surrounding the oil atomizing nozzle, and is not subject to control by the modulating mechanism.

An outer chamber 8 surrounds the pilot air chamber 2, and is provided with an intermediate air port reduction nozzle 9 concentrically disposed around the pilot air exit ports and is in communication by duct I! and annular chamber M with a main air supply C subject to the modulating mechanism. Vanes or like blades l2 are provided near the inlet of the intermediate air port reduction nozzle 9 to impart swirl to air issuing therefrom.

An annular disc member l3 forming part of an air register, AR, is disposed forwardly of, and

in axial alignment with the nozzle and ports already mentioned, and is adjustably aifixed (by screw thread i3a) over a comparatively larger central opening it (also see Figure 3) in an annular chamber l of the casing. The annular chamber Hi is formed in portion l5 of the casing.

The central opening 16 in the casing, behind the annular disc member i3 is provided with vanes ll equidistantly and approximately tangentially spaced around the central opening, so

that air forced through the chamber to subsequently enter a combustion chamber will be caused to whirl.

The annular chamber i l of the casing, and other parts of the burner carried thereby, is adapted to be screwed or suitably afiixed to the relative end of a generator housing in such a manner that the air register AR, oil atomizing nozzle l and other components are directed into the combustion chamber l8 of the generator, with an interposition of an annular firing block E9 of fire brick or like material which may be secured to the inner side of the end of the housing of the generator.

An air chamber 2! (hereinafter referred to as a controlled air chamber) concentrically surrounding the fire brick in the combustion chamber of the generator is provided with outlet ports or slots 22 circumferentially arranged to make connection with the annular chamber i l of the casing of the burner, and the main air supply for the burner, subject to control by the control or modulating mechanism M, is conveyed to the controlled air chamber.

The modulating mechanism M (see Figure 4) for controlling the main supply of air to the burner from the high pressure air supply AS includes a piston 26 accommodated within a cylinder 2? and mounted upon a spindle or rod 23 which passes through a bearing 29 in one end wall 30 of the cylinder. The cylinder is approximately equal in length to the piston. An outlet port Si is provided on that wall of the cylinder, and it will be seen that by controlling the amount of air passing from the outlet port, modulating or controlling of the main supply of air, and oil, to the burner may be effected.

Air under pressure from the source of supply AS is directed through a central opening in an annular sealing ring 32 disposed in alignment with the periphery of the adjacent end of the piston and, when the piston is moved forwardly towards the end wall 38 of the cylinder air may pass around the edge of the piston 26 thence to the controlled air chamber 2| and main air chambers of the burner. However, when the edge of the piston, at one extremity of its stroke, engages with the sealing ring 32, air is substantially prevented from reaching the main air chambers of the burner.

A relatively small hole 33 is provided through the piston thus allowing a small quantity of air under pressure to bleed through the piston from the high pressure air source to the chamber 34 at the forward end of the cylinder, formed between the front of the piston itself and the end wall of the cylinder.

The circumference of the piston is provided with a circumferential groove 33 into which a number of small ports 31 leading from the inner side of the piston, are directed, so that air under pressure may also bleed through the ports into the groove.

The spindle or rod 28 of the piston, emerging from the cylinder through the bearing 29 in the end wall, is provided with a rounded end 28a which bears against one end of a pivoted lever til The remote end of the lever is provided with a roller 42 which is adapted to engage with a cap 59 on an actuating rod 43 of an oil control valve V. Thus, movement of the piston within the cylinder causes the lever to be turned about its pivot thus actuating the spindle of the oil control valve to permit more or less oil to pass to the burner.

Suitable adjustment means such as screw and nut 44 may be provided to vary the operative engagement of the roller 42 upon the lever with the cap 59 of the oil control valve to provide for appropriate adjustment in operation, i. e. to alter the relative movement of the oil control valve responsive to movement of the piston and lever.

Spring 46 or like means are provided to normally influence the piston, and the lever actuating the oil control valve, in such direction that the edge of the piston will tend to engage the sealing ring 32 to cut off the main supply of air to the burner, and the oil control valve towards closed condition.

A suitable apparatus (indicated in Figure l and including an air ballast chamber AB, orifice valve 0 and control device CD) for effecting control of the air passing from the port 3| to exert the desired control over the burner, commensurate egeeoyzos with the pressure of steamggenerated by "the generator, as describedin the following:

Thus, the air ballast chamber ABis connected through the orifice valve 0 toa part of the generator under working steam pressure, whereby differential pressures at opposite sides of the orifice valve will effect movement of adiaphragm in the casing of: the controldevice CD, which diaphragm will in turn open or close acontrol valve connected to the port 3i to effect control of air passing therefrom.

In operation, and assuming that the outlet port 3| in the end wall of the chamberzi l in advance of the piston 26 is open, orxrelatively unrestricted, the piston Will'be caused to move towards the end walLa-gainst the'infiuence of the spring means it, by the pressure of the air from the high pressure source, and main air will be permitted to pass to the controlled air chamber 2! and to the burner. However, should the outlet port be closed or restricted then the air which may bleed through the relatively small hole 33 in the piston will permit a substantially equal pressure to obtain on'both sides of the piston, whereupon the spring means will influence the piston to move towards and engage the sealing ring thus closing the peripheral opening through which the main supply of air from the pressure source has to enter to pass to the burner. is retracted with the spindle of the piston, allows the oil control valve V to move towards the closed position and restrict the flow of on to the burner.

When the piston engages the sealing ring, the pilot air is the only air under pressure which is supplied to the burner through conduit BC as it is not subject to control or restriction by the piston or any modulating mechanism.

The oil control valve (see Figure 5) may comprise a body 5! with two interior compartments separated by a conical valve seating 52, each compartment being provided with a port for the inlet and egress of oil from and to conduits, conduit 53 from a source of supply and the other conduit 3 to the burner. A spindle 54, to which is affixed a conical valve facing 56 adapted to engage on the seating 52 is accommodated in one compartment and is influenced by spring 5'! or like means to normally close the valve on the seating. An actuating rod 43, in alignment with the spindle, may pass axially through the body and be provided with a guide cap 59 or the like adapted to be engaged and depressed by the roller 42 which is actuated by the lever M, in turn operated by the piston 2'5.

Subsidiary ports 6! and 62 are preferably provided in the body member, one on each side of the valve seating 52, communication between the two subsidiary ports being subject to restriction by an adjustable needle valve 63 or the like so that a limited supply of oil may by-pass the valve 56 when the latter is fully closed to permit the burner to function on pilot or at a greatly reduced burning intensity.

When the piston 26 is fully engaged against the sealing ring 32, and the outlet port 3! from the chamber 34 in advance of the piston is closed or restricted, the pressure in this chamber will approach equality with the pressure on the other side of the piston; and, as most of the piston will be out of its cylinder 21 under these circumstances there is a tendency for air under pressure to leak from the chamber 34 past the outer surface of the piston and into the con- At the same time the lever ll which trolled'iairbhamber. 2| which will be at atmospheric pressure owing to the source of. air under pressure having 'beenxcut off. The groove'tt around the piston, connected through the small ports 31 to the pressure side of the piston, prevents this from occurringas pressure air is always supplied to this groove and acts as a ring of sealing pressure.

It has been found that introducing a main supply of air under pressure through an air register in a manner hereinbefore described greatly assists in theatomizing of the fuel oil without the air actually passing over the oil atomizing nozzle of the burner.

'The orifice in the air register annular diso member I3 is preferably smaller in diameter than the central opening of the easing into the firing block l9 and the'whirling air, as it nears the centre of the air register, spins and spills over into the firing block, and notwithstanding that the pressure in the "firing block and'combustion chamber may be .above atmospheric pressure, the spilling over into the firing block forms a vertex which causes a definite constant suction in through the. orificein the air register which is adjustable for varying conditions of operation as required.

In effect, although a positive pressure is being created inthe combustion chamber, and although the burner nozzle is'not completely enclosed, it has been found that there is not the slightest tendency for the flames to flash back around the nozzle of a burner according to the present invention.

It has also been found that, even when running on a very rich or a very lean combustion mixture, such a burner shows very little tendency to go out and burns very steadily all thetime.

The burner may be operated, and varied quickly over the full range from pilot to fully open position without the slightest tendency to flutter or blow back.

As far as is known, the foregoing arrangement for introducing additional atomizing air is not in use today on any other make of burner. When the burner is operating on heavy oil, it has been noticed that the oil leaves the atomizer itself in fairly large globules but, as the oil passes through the orifice in the air register it is picked up by the air whirling in through the air register and is broken up into a very fine spray.

In tests, a typical burner has been operated using from as low as six gallons of oil per hour to as high as thirty gallons per hour, with satisfactory operation over the whole range.

It is probable that the output of the burner could be greatly increased by utilizing an air register of comparatively larger dimensions, and such a modification is intended to be included within the scope of the invention.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

l. Controlling apparatus for effecting control of an oil burner capable of variation in the intensity of burning comprising an annular, chamher, an oil supply nozzle mounted in said annular chamber so as to be supplied with pilot air from said annular chamber, a pilot air inlet to said annular chamber, means feeding oil to the nozzle, a secondary main air chamber having its outlet concentric with said annular chamber, a source of high pressure air supply, conduit means for conveying air to the secondary main air chamber, modulating mechanism in the conduit means powered by the pressure of the high pressure air controlling the main supply of air from the source to the secondary main air chamher and simultaneously controlling the rate of oil feed to the nozzle, control means for the modulating mechanism, and a conduit from the source of air supply connected to the pilot air inlet of the burner to bypass air under pres sure from said air supply around the modulating mechanism.

2. Controlling apparatus according to claim 1 wherein the modulating mechanism includes a control valve for the oil feed and an air operated piston acting as a valve for controlling the main supply of air to the burner and simultaneously providing the motive power for actuating said oil feed valve.

3. Controlling apparatus according to claim 1, wherein the modulating mechanism comprises a cylinder, a piston therein, the piston mounted upon a spindle which extends through an end wall of the cylinder, and an annular sealing ring having an opening through which main air under pressure from the source of supply may be directed, said ring being spaced axially from the cylinder and remote from said end wall and being engageable by said piston when the latter is withdrawn from said cylinder in order to cut oil the passage of main air to the burner, the piston having a bleed hole therethrough and the end wall of the cylinder having an outlet port therethrough adapted to be variably restricted to control the operation of the modulating mechanism, the spindle of the piston being adapted to actuate an oil control valve, and having a spring member to normally influence the spindle, piston and oil control valve to reduce or cut off the main supply of air and oil respectively.

4. Controlling apparatus according to claim 1,

wherein the modulating mechanism comprises a cylinder, a piston therein, the piston mounted upon a spindle which extends through an endwall of the cylinder, an oil control valve and an annular sealing ring having an opening through which main air under pressure from the source of supply may be directed, said ring being spaced axially from the cylinder and remote from said end wall and being engageable by said piston when the latter is withdrawn from said cylinder in order to cut off the passage of main air to the burner, the piston having a bleed hole therethrough and the end wall of the cylinder having an outlet port therethrough adapted to be variably restricted to control the operation of the modulating mechanism, the spindle of the piston being adapted to actuate the oil control valve, and having a spring member to normally influence the spindle, piston and oil control valve to reduce or cut off the main supply of air and oil respectively, and wherein said piston is provided with a circumventing groove into which a number of small ports leading from the air pressure supply side of the piston are directed.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,063,352 Jacobs June 3, 1913 1,633,502 Staley June 21, 1927 1,679,830 Lang Aug. 7, 1928 1,923,614 Clarkson Aug. 22, 1933 2,000,733 Avery May 7, 1935 2,104,221 Colston Jan. 4, 1938 2,247,768 Huyler n- July 1, 1941 2,253,160 Arnold Aug. 19, 1941 2,397,987 Seminger Apr. 9, 1946 2,565,879 Perle Aug, 28, 1951

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