US2311404A - Conversion oil burner - Google Patents

Description

Feb. 16, 1943. A. MACCHI CONVERS ION OIL BURNER Filed Feb. 24, 1940 Fi gJ.

Inventor Aldo Macchi,

HIS Attorney LGD Patente eh, H6, 1943 CONVERSION 01L BURNER Aldo Macchi, ileville, N. 3., assignor to General Electric Comny, a corporation of New York Application February 24, 1940, Serial No. 320,557

6 Claims. (Cl. 158-76) The invention relates to oil burners and the principal object is to provide an improved automatic electrically operated oil burner unit of the conversion type, which is fully enclosed so as to be quiet and clean and embodies an integral automatic flame detector and control so that the unit may be readily applied to various types of furnaces or boilers.

A specific object is to provide an improved conversion oil burner nozzle with an improved form of integral automatic flame detector and with an improved form of base and enclosing casing construction whereby substantially standard and separate burner and automatic control parts can be unified and electrically interconnected in cooperating relation thereby insuring that all parts of the unit work properly together and facilitating the proper installation, and servicing of the unit irrespective of the type of furnace or boiler to which the unit is applied.

' A more specific object is to provide an improved conversion oil burner construction having an adjustable base pan and upright wall. mounting structure with a complementary removable enclosing jacket or cover for the electric motor driven air and oil upply mechanism, and the automatic electric control parts or the unit, and with the nozzle and flame detector control parts, which must project into the furnace, removably connected to the wall in proper operating relation with the other parts. This improved mounting and enclosing structure protects the electrical and the oil and air supply mechanism from the nozzle heat, provides for quiet, clean and emcient operation, enables the burner nozzle height to be readily varied by raising or lowering the base pan and wall independently of the jacket to conform with the height of the furnace door opening and also enables all the principal parts of the unit to be readily accessible upon removal of the cover for inspection, repairs, removal or replacement, without disturbing the main burner nozzle tube after it is once sealed in its proper position in the refractory walls of the furnace combustion chamber.

Another object of the invention is to provide an improved air injection construction ad- Jacent the end of the conversion burner nozzle extending into the combustion chamber for receiving an integral automatic flame detector, whereby a quick and reliable response oi the automatic flame detector control is obtained without subjecting the temperature responsive parts to excessive or destructive temperatures. To meet the Patent Ofice requirements my. divi-- height.

sional application Serial No. 440,378 was filed April 24, 1942, with claims to this feature.

A further object is to provide an oil burner having a very low nozzle tip temperature during the running period as well as after shut down of the burner operation. This low tip temperature prevents the forming of tarry or carbon residues in the nozzle, thus avoiding the tendency for such residues to slowly accumulate and clog the nozzle parts.

Other objects will appear in the following description of the accompanying drawings illustrating preferred embodiments of the invention and in which Figure 1 is a side view partially in section of an automatic electrically operated conversion oil burner unit provided with the improvements of the present invention; Fig. 2 is a top view partially in section of theoil burner unit shown in Fig. 1, and Fig. 3 is an end view of the burner nozzle showing the improved location of the improved flame detector control part adjacent the end of the nozzle.

As shown in Fig. 1 the conversion oil burner unit comprises a base it with the adjustable legs I I upon which base are mounted all of the principal operating and control parts of the conversion oil burner unit including the electric motor driven air blower and air and oil pumping mechanism I2, the high voltage electric ignition transformer It, the automatic starting, stopping and sequence timing control mechanism It as well as the complete burner air and oil discharge nozzle assemblage it including the main combustion air discharge nozzle Ilia which is adapted to be sealed into the refractory wall I6 01 a boiler furnace or other type of furnace to which the conversion oil burner unit is applied and the oil atomizing nozzle 2i and other parts which are mounted inside of the main nozzle lta. The three supporting legs H are threaded into the base it so as to be independently adjustable, thereby permitting the entire burner nozzle assemblage E5 to be raised or lowered to the proper height from the floor upon which the unit is mounted to conform with the furnace combustion chamber and also permitting leveling of the unit at the desired The base it preferably is of pressed metal formed into the shape of an oil or drip pan as shown in the drawing.

The motor driven mechanism it constitutes the electric motor driven oil'and air pressure supply means for theburner nozzle assemblage it and preferably is of the improved type described and claimed in the Lum Patent 2,032,291,

granted February 25, 1936, although any other suitable type of combustion air blower and atomizing air and oil pumping means may be provided for supplying the burnernozzle IS with oil and combustion air. The motor driven mechanism |2 preferably is resiliently mounted upon the base ID by means of suitable springs |1 so as to avoid transmission of noise and vibration to the base.

The electric ignition transformer I3 is shown as of the conventional type with its high voltage terminals l8 connected through suitable conductors l3 to produce an are between the two spaced apart ignition electrodes 20 which are located inside the combustion air nozzle lie and above and closely adjacent to the end of the oil atomizing nozzle 2| so as to ignite the atomized oil stream discharged therefrom into the combustion air stream discharged from nozzle I611. The

oil 'atomizing nozzle 2| preferably is of the improved construction illustrated and described in my copending application, Serial No. 320,558,- filed concurrently herewith.

The proper energization of the ignition transformer I3, the electromagnetically operated oil flow control valve 22, and also the electric motor driven air and oil pumping mechanism |2 from a suitable source of electric power are under the control of a suitable oil burner timing sequencing control switch mechanism ll which may be of any desired type although preferably it is of the type which is described and claimed in the Eaton Patent No. 2,134,550, granted October 28, 1938. The various control details are well known in the art and are not deemed essential to proper understanding of the present invention and hence are not shown other than the transformer |4a for energizing the usual low voltage room thermostat control circuits and the control motor Ilb for operating suitable sequencing cam switch mechanism for coordinating the energ'ization of the proper burner control circuits at proper times, in conjunction with the flame detector switch mechanism 50 which is described in more detail hereinafter.

As shown in Figs. 1, 2 and 31, the burnercombustion air supply nozzle |5a preferably is mouid ed of cast iron and provided with suitable mounting lugs 25 so that it may be detachably mounted upon the upright wall 26 which extends upward- 1y from the right-hand end of the base l0 and is suitably secured thereto as by spot welding. The removable jacket or enclosing casing 21 for the unit cooperates with the upright wall 26 to enclose all of the operating parts of the oil burner unit except the nozzle assemblage IS on the outside of the wall. The upright wall 26 is provided with suitable openings for receiving the bolts 28 which detachably mount the main combustion air nozzle I50. within which all the other nozzle parts are mounted.

The upright wall 26 has suitable openings formed therein through which extend the oil supply pipe 29 and the air supply pipe 30 which interconnect the inner oil atomizing 'nozzle 2| with the air compressor and oil pump of the motor driven mechanism l2. As shown these oil and air supply pipes 29 and 36 extend through the nozzle tube 3| which is mounted along the axis of the main combustion air nozzle i511. and adjacent the end of which the oil atomizing nozzle 2| is mounted. The nozzle tube 3| also carries the supporting bracket 32 in which the ignition electrodes are mounted in proper spaced relation with the atomizing nozzle 2| to effect ignition of the atomized oil stream discharged therefrom. A suitable combustion air whirler or spinner 33 is mounted upon the nozzle tube 3| with the ends of the blades thereof extending into sliding engagement with the interior of the combustion air nozzle |5a adjacent the discharge end thereof. Thus the'spinner 33 serves to maintain the nozzle tube 3| centrally at the axis of nozzle. l5a.

The oil and air supply pipes 23 and 30 are suitably secured to a removable mounting plate 34 which is removably mounted in spaced apart relation with the removable mounting plate 34a to which tube 3| is secured so as to permit a flow of air through the nozzle tube 3| from inside the enclosing jacket 21 due to natural draft and of the burner unit is obtained by allowingsome fan air to enter the tube 3| through the hole 3|a which is located in tube 3| so that the air flow resistance (Fig. 1) ofiered by the air spinner 33 will cause some combustion air to enter tube 3| through hole Ma.

The upright wall 26 also is provided with another suitable opening adjacent the top thereof for transmitting air under pressure from the motor driven blower 36 to the inside of the enlarged offset air inlet scroll casing portion 36 of the combustion air nozzle IS the open end of which is closed by the wall 26. The pressure of the air supplied from blower 35 is regulated by means of a suitable adjustable damper 35a located adjacent the blower inlet. As shown in Figs. 1 and 3 the enlarged offset air inlet scroll casing portion 36 of the air nozzle l5 forms in conjunction with the sealing upright wall 26 a flow directing chamber 36a for directing the combustion air flow downwardly and imparting a slight rotating motion thereto upon the entrance of the air under pressure to the nozzle l5. This enlarged offsetscroll portion 36 of the air nozzle l5 distributes the combustion air coming from the blower 35 through chamber 360. so that it flows in equal amounts between the three equilaterally spaced fixed baffles 361) thereby improving the stability of the flame. The converging air discharge tip |5b of the combustion air nomle l6 preferably is made removable so that the tip lib may be replaced whenever required as for example in case an extension of the air and oil nozzles should become necessary for properly installing 'the conversion oil burner unit in a large size warm air furnace. The enlarged oi!- set scroll portion 36 of the air nozzle |5a serves to intercept much of the direct radiant heat from the furnace combustion chamber and transmit such heat to the air flowing into the air nozzle l5a. thereby improving the combustion eiiiciency and at the same time preventing overheating of the operating part of the burner unit located behind the wall 26 within the enclosing jacket or casing 21 closely adjacent the combustion chamber.

The air flow connection from the scroll housing of the blower 35 into the combustion air inlet opening 31 formed in the upright wall 26 preferably is made flexible and resilient by means of a suitable felt bushing 38 which is enclosed within the bushing mounting casing 39 which in turn is removably mounted upon the upright wall 26 in any suitable manner. The flexible felt bushing 33 prevents transmission of mechanical vibration from the electric motor driven blower compressor mechanism i 2 to the wall 26 and also serves to prevent leakage of the air under pressure in its passage from the blower housing 35 into the flow directing chamber 36a.

The upright wall 2% also is provided with a suitable opening for mounting the detachable coupling 68 of the oil supply pipe 40a. Coupling M3 is connected through the flexible looped pipe at with the intake port #32 of the oil pump embodied in the electric motor driven oil and air mechanism i2.

With the improved conversion oil burner unit construction as above described it will be observed that all of the main operating parts of the burner are readily detachable from the cast iron air nozzle [5a after it is once sealed in proper operating condition in the furnace combustion chamber as illustrated in Fig. 1. By loosening the mounting bolts 2! and disconnecting the oil supply .pipe 60a and the electric power supply and control cable 42, the entire unit including the base it, upright wall 26 and all the parts mounted thereon, and also including the nozzle 2!, the inner nozzle tube at, and electrodes 20 may be moved as a unit to the left and thereby detached entirely from the combustion air nozzle l5. This facilitates ready inspection, replacement or repair of all of the operating parts of the burner unit. Furthermore, by merely lifting the enclosing jacket 2? which rests upon its bottom edge upon the floor entirely independently of the main supporting base 10, all of the main essential operating parts of the burner and control mechanism are made readily available justment or replacement.

As shown in Fig. 2 the opposing upright edges 45 of the removable enclosing jacket 27 extend in overlapping sliding relation with the opposite side edges of upright wall 26. Thus when the base it is adjusted to its maximum height so as to bring the upper edge of wall 28 into overlapping sliding engagement with jacket 27 as shown in Fig. 1 then all combustion air is drawn into the blower air intake opening 35a inside of the" enclosing jacket 27 after passing between the opposing upright edges 45 of the jacket 2'! and under the base ID from the right-hand side of the enclosing jacket closely adjacent the furnace combustion chamber as indicated by the arrows in Fig. 1. In case the base It should be lowered so as to decrease the area of the air inlet opening extending between the opposing upright edges 45 of the enclosing jacket 21 below the base It then an equivalent area of air inlet opening is obtained above the top of the wall 26. Hence the necessary air inlet area into the jacket 21 isobtained irrespective of the height at which the base i0 is mounted. In any case the air inlet opening into jacket 21 is directly adjacent the furnace combustion chamber so as to draw therein any heated air, fumes or products of combustion that may be released from the furnace. This location of the air inlet opening into jacket 27 also serves to suppress the transmission of noise from the inside of the enclosing .casing 21 to the surrounding atmosphere since any noise vibrations which may pass through the air inlet opening are intercepted by the furnace.

The improved burner unit construction described above provides for maximum freedom in the construction, size and location of the various essential elements of the burner air and oil supply and ignition mechanism mounted upon the base it without interference with the other coopfor repair, ad-

crating elements. Each main essential element may be separately manufactured in a standard form or size and mounted independently of the others but in proper spaced and cooperating relation therewith. This promote improvements in the structure of the severalelements and facilitates the final interconnection thereof in proper cooperating relation in the improved conversion oil burner unit. Any one of the various essential elements may be improved in structure with a minimum of interference with the other elements.

In the preferred form of the invention illustrated in the drawing, the automatic burner control mechanism It is shown mounted directly upon the upright supporting wall 26 with the flame responsive switch mechanism 56 preferably constructed as an integral part of the main automatic control It and arranged to be responsive to combustion conditions immediately adjacent the end of the burner nozzle. It will be understood, however, that the flame responsive switch mechanism may be made a 'separate element from the main automatic sequencing control switch mechanism It if desired. In the form shown in Fig. 2 the flame responsive switch mechanism comprises a base plate 5| to which is attached the supporting bracket 52 carrying the pivoted switching arm '53 having the contact 54 carried at the end thereof between the two cooperating contacts 55 and 56. The pivoted switch arm 53 is biased by spring 57 to engage contact 54 with operated against the bias of spring 51 by the contact 68. The pivoted switch arm 53 is the sliding pin 58 which is connected through the agency of the quartz rod 59 which is relatively non-expansible upon temperature changes with the temperature responsive expansive tube 50. The temperature responsive expansive tube 66 preferably is formed of nichrome or other suitable high temperature expansible material and is mounted at the end of the supporting tube at which extends through the air inlet casing 35 and in turn is supported from the base plate 5! The burner combustion air nozzle nozzle I5 is provided with a special auxiliary housing 15 extending from one side thereof adjacent the discharge end of the nozzle. into the combustion chamber of the furnace. {This special auxiliary housing 15 is formed with a substantially U- shaped internal passageway 750. with bolts ends of the U-shaped passage opening directly into the furnace combustion chamber as indicated more clearly in Figs.'2 and 3. In one leg it oi this internal U-shaped passageway 15a, the temperature responsive expansible element 60 of the flame detector is located. A small auxiliary air supply nozzle Ti is connected with the laterally ofiset scroll portion 36 of the combustion air supply nozzle I5 so as to admit a jet of air under pressure from the scroll portion 36 into the other leg 18 of the U-shaped passage the. Thus the jet of air under pressure issuing team the nozzleit into the passage it sets up an injector action which produces a circulation of the products of combustion from the combustion chamber through the U-shaped passage itself and back again to the furnace combustion chamber. In this way a flow of the products ofcombustion from the furnace combustion chamber is drawn by the injector action set up by the auxiliary air nozzle ll over the temperature responsive tube element 60 of the flame detector. Thus the element 68 although located entirely outside the furnace combustion chamber is made directly responsive to the temperature conditions produced by combustion in the furnace whenever the blower 85 isoperating to supply air under pressure to the injector nozzle 11.

=Whenever the oil burner unit is started into operation by means of the suitable automatic control mechanism I which ordinarily is under the control of a room thermostat or other automatic condition responsive control, oil and air will be supplied under pressure from the motor driven oil and air supply mechanism H to the burner atomizing nozzle 2|. At the same time combustion air under lower pressure will be supplied from the blower 35 to the inlet 31 of the combustion air nozzle l5. This flow of combustion air passes along and cools the outside of the nozzle tube 3| within which the oil atomizing nozzle 2| is mounted. Also a further cooling air flow is drawn through the inside of the nozzle tubeSl directly over the oil atomizing nozzle 2|. This cooling air flow through the inside of the nozzle tube 3| is jointly dependent upon the injector action produced by the blower air flow at the tip of nozzle l5 and also upon the natural draft produced by the furnace. Hence the cooling air flow through the inside of nozzle tube 3| will continue independently of the operation of blower 35 and prevent overheating of nozzle 2| when the burner unit is shut down.

When the atomized oil stream issuing from the nozzle 2| is ignited from .the electric arc established between the electrodes 20, combustion normally will be established within the furnace combustion chamber. The arcing electrodes are energized from the high voltage terminals of the ignition transformer Hi, the primary of which is suitably energized during the proper interval by the operation of the sequencing timing control mechanism l4.

Due to the injector action produced by the auxiliary air nozzle 11, some products of combustion will be drawn from the furnace combustion chamber over the temperature responsive expansible tube 60 thereby producing a movement of the flame responsive switch arm 53 to indicate the presence of combustion in the combustion chamber. In case combustion should thereafter fail, the tube 60 wil1 cool thereby reversing the operation of the switch arm 53 to in-- dicate the absence of combustion. It will be understood that the flame detector switch 50 is intended to cooperate with the burner control mechanism It so as to shut down the motor driven oil and air supply means in case of combustion failure in the manner which is well known in the art. Likewise the flame detector switch 50 will cooperate with the control mechanism It to prevent continued operation of the motor driven compressor mechanism l2 in case combustion is not established within a limited time interval after the burner unit is started into operation. This prevents accumulation of unburned oil in the combustion chamber which might result in puffs, explosions or other dangerous conditions.

With the improved conversion burner unit construction described above, the flame detector 5!! and control mechanism It forms an integral part of the unit and hence materially simplifies the installation problem. All of the various cooperating parts may be properly mounted, interconnected in the proper cooperating relation and tested together. Thus all that is necessary for installation is to seal the burner air nozzle l5 in the furnace combustion chamber and provide the necessary oil and electric power supply and control connections to the unit.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an oil burner unit, in combination, a drl pan having adjustable supporting legs extending from the bottom thereof, and having an upright wall at one side thereof, electric motor driven oil and air supply means removably mounted upon said pan, burner means connected with said supply means including an oil discharge nozzle and av combustion air discharge tube carried by said wall and provided with means for removably mounting said nozzle through said wall inside said tube and an independently supported removable cover having an opening with the edges thereof slidably engaging said wall for enclosing said air and oil supply means and providing a constant area air inlet thereto independently of the adjustment of said legs.

2. In an oil burner unit, in combination, an adjustable supporting base including a drip pan having an upright wall at one side thereof, electric motor driven oil and air supply means removably mounted upon said drip pan, 9. removable jacket cooperating with said wall for enclosing said supply means, and burner means connected with said supply means including an oil discharge nozzle and a combustion air discharge tube carried by said wall and provided with means for removably mounting said nozzle through said wall inside said tube,

3. In an oil burner unit, in combination,- a supporting base provided'with adjustable legs for leveling the base at varying distances above a floor level, an independently floor mounted jacket surrounding said base and provided with an air inlet opening at the bottom thereof, electric motor driven oil and air supply means mounted on said base within said jacket and including a blower provided with an air inlet opening inside said jacket and a burner nozzle removably mounted on said base and having oil and air passages removably connected with said all and air supply means. a

4. In an oil burner, in combination a combustion air discharge nozzle adapted to be mounted in the wall of a furnace combustion chamber and having a lateral air supply scroll casing at one end thereof provided with a removable wall extending transverse the axis of said nozzle and with an air inlet opening offset from the axis of said nozzle formed in said wall, an oil supply pipe mounted in said removable wall for removal as a unit therewith and extending within said air nozzle and having an oil nozzle at the end thereof for discharging an atomized stream of oil along the axis of said air nozzle adjacent the discharge end thereof and electric motor driven oil and air supply means connected with said removable wall for removal as a unit therewith, said supply means including an air blower discharging into said offset air inlet opening formed in said wall and an oil pump for supplying oil under pressure to said oil supply pipe.

5. In an oil burner, in combination, a supporting base plate having adjustable legs extending from the bottom thereof and having an upright wall at one side thereof, an air discharge nozzle tube carried by said wall and having casing means abutting said wall to form a lateral air inlet chamber for said tube, an oil discharge nozzle removably mounted within said tube adjacent the discharge end thereof, motor driven oil and air supply means removably mounted upon said base plate and having a removable oil supply conduit extending through said casing means and said air nozzle tube to supply oil to said oil discharge nozzle and having an air supply conduit removably connected with said air inlet chamber,

and a. removable Jacket cooperating with said wall for enclosing said supply means.

6. In an oil burner, in combination, an adjustable height base plate having an upright wall at one side thereof, burner means including an 10 motor'driven oil and air supply means mounted' on said base including an oil pressure supply means connected with said oil supply conduit and a blower connected with said air inlet chamber.

ALDO MACCHI.

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