US2643708A - Oiol burner carburetion - Google Patents

Description

June 3@, 1953 SHERMAN 2,643,708

OIL BURNER CARBURETION Filed May 4, 1945 Inventor Morris sherman Attorney wwm/ Patented June 30, 1953 OIL BURNER CARBURETION I Morris Sherman, Port Washington, N. Y., assignor to Preferred Utilities Manufacturing Corp., New York, Y., a corporation of Delaware Application May 4, 1945, Serial No. 591,957 3 Claims. (Cl. 15828) 1 I This invention relates to oil burners and has particular reference to improving the mixture of air with atomized oil particles to form a com.- bustible gas. Heretofore the intimacy of mixture obtained for combustion purposes has been notoriously poor and particularly has this'been true of the so-called gun type or conventional pressure 'atomizing burner. Various expedients have been resorted to ma effort to improve the mixture and thus increase the efliciency of operation of the burner. Among them have been the helical rifling of air discharge passagesadjacent the atomizing nozzle for the. purpose of obtaining a swirling or circulatory air current in proximity to the oil'discharge point, the use of vanes to accomplish this same purpose, and

sometimes the use of openings inclined with reference to the path oithe' oil discharged to direct the air toward the oil and forwardly to aid in fiame propagation.

Among the objects of this invention is to obtain an intimacy of oil and air mixture in the primary combustion zone which has hitherto been unobtainable. The pressure atomizing burner embodies a very efficient atomizing principle wherein the oil is mechanically atomized at the discharge nozzle and thereby broken up into small particles which in eiiect constitute a fog. But, since no really eflicient gasifying or mixing arrangement is available, the over-all efiiciency of such a burner is very small indeed. For example, burners available today develop at the stack a C02 content of around 7%. For a number of years a range of between 3% and 10% CO2 at the stack has been, accepted as indicative of relatively enicient combustion. By the use of my improved method of mixing or carbureting the air and oil I have been able to obtain atithe stack as high a C02 content as 12%. Inasmuch as a C02 content of 15% isrecognized as indicating substantially no excess air, and, consequently relatively perfect combustion, it will be apparent that my improvement is substantial. In, conventional burners the path of the air discharged into the primary combustion zone around the end of the oil atomizing nozzle is substantially parallel to the axis of oil discharge. Consequently the two masses tend to travel in parallel paths and the only factor functioning positively to create an intimate mixture is the cyclonic movement of the air obtained'bythe vanes or rifle nozzles described above Under these circumstances the air forms what may be regarded as a substantial annulus'surrounding the mechanically atomized oil as a core and, while some of the air unites with the oil particles to form a combustible gas, there is. a very considerable quantity thatodoes not, That portion of the air which fails .to mixpasses through the heater asexcess air,,thus creating tWo obvious wastes, (1) that air which fails to unite with any oil particles and can serve no useful purpose, and (2) such oil particles as are not supplied with a sufiicient amount of air for combustion purposes and pass through the heater as oil vapor. the heat created by actual combustion is wasted under the circumstances to whatever extent it is used to raise the excess air to stack temperature.

My improved method and apparatus for obtaining an intimate mixture, or in effect carbureting the oil, involves discharging the mechanically atomized oil in one direction into what may be termed a mixing or gasifying box or chamber, directing the primary combustion air under a controllable static head into said mixing chamber in a direction to impinge upon the axis or core of the oil discharge, and at the same time eliminating any pressure head within the mixing chamber other than the static head of air and the head behind. the oil dischargefrom th atomizing nozzle. Preferably the combustion air is fed under the said static head from a large number of separate discharge points extending entirely around the primary combustion zone and the core formed by the mechanically atomized oil discharge, the direction of said air discharge being normal to the directionof oil discharge and arranged to impinge upon the center of said core.

Broadly speaking, the improvement comprises a combination of mechanical atomization, which asabove suggested has been found far superior to atomization by means of ai jets, and improved carburetion of the oil so atomized to obtain a thorough mixture of the two to form,v a combustible without the aid oi'excessair, thus approaching maximum obtainable eificiency which of course makes for increased economy of operation.

Various. other advantages and important features of the invention will become more apparent from the following description taken. in conjunction with the drawings, wherein likenumerals refer to like parts throughout, andwherein:

- Figure l is. a side elevation Of a burner em-- bodying my improved gasifying chamber, which latter is shown in section and partially broken away; and I Fig. 2 is a section through l! of Fig. l.

The burner illustrated embodies a conventional casing which houses the fuel pump, fan and other operating parts for receiving fuel from the storage tank and forcing it through an axially disposed discharge tube i l to the oil atomizing nozzle 1 while at the same time forcing air through draft tube 16 to discharge openings.

A cylindrical combustion; head housing I is preferably setin an opening provided therefor Furthermore, it is of course apparent that in furnace wall i8, flame from the combustion head being propagated into the secondary combustion chamber 20. The combustion head housing is preferably a casting which is positioned by means of an anchor casting 5 to which it is secured in suitable fashion, such as by mounting screws i2. The anchor casting is in turn secured as by means of set screws H to an adapter ring 6 which is fixedly positioned around the open end of draft tube to. The particular form; in which the invention has been illustrated herein, including the anchor casting and adapter ring, is suggestive of the obvious possibility that the invention may be readily embodied in standard equipment now in use. This feature, however, constitutes no part of the broad phase of the invention.

Housing I is flanged radially inwardly at its forward open end as indicated at 22 and provided with an inwardly extending annular flange or series of fins 24 adjacent its other end. Where a flange is used, openings are provided therein to permit the passage of air as indicated in the drawing, while the spacings between fins serve this purpose if such construction is used.

A cylinder base in the form of an annular ring 3, which may be a casting, is secured within the combustion head housing as by means of a radial flange or fins 26 which are secured to flange or fins 24 extending inwardly from the housing. Such securement may be obtained by means of screws, as indicated, or other suitable attaching means.

In the form shown cylinder base ring 3 is provided with a shoulder 28 over which is friction fitted one end of a perforated cylinder 2, which latter is preferably of alloy steel. The other end of the cylinder seats within the opening provided by flanges 22 at the open or discharge end of the combustion head housing. A removable nozzle plug 4 covers the opening in ring 3, such nozzle plug being removably secured to the ring as by means of the shoulder and flange arrangement designated broadly by the numeral 30.

The removable nozzle plug 4 is provided with an opening aligned with the axis of cylinder 2 in which is secured nozzle adapter carrying atomizing nozzle 1. The insulated electrode 8, like the nozzle adapter, extends through an opening in plug 4, the electrode tip preferably being offset in the direction of the atomizing nozzle and in conventional proximity thereto. Ring 3 is provided with a vacuum breaker orifice 9: for purposes hereinafter to bedescribed.

When the burner is in. operation oil fed through tube i4 is mechanically atomizedby-nozale 1, creating a substantial fog within the primary combustion space inside perforated cylinder 2. Air from the fan is forced into the annular space between perforated cylinder 2 and the combustion head housing i to thereby build up a static head within the chamber. The pressure of the head may be controlled by varying the speed of the fan or by varying the number and/or size of the perforations in thecylinder 2-. Air capacity of the fan and the number and. size of perforations may be predetermined forany given conditions to obtain the maximum econ.-

omy.

The vacuum breaker orifice performs several functions, one during the ignition period and two simultaneously during operation of the burner. During the ignition period, after the fan has been set inoperation, the relatively'small stream of air admitted through the orifice and so di- 4 rected as to impinge on the tip of the electrode functions to bend the ignition flame toward the atomizing nozzle 1, thus facilitating ignition.

During operation of the burner the same small stream serves to avoid any tendency to form a "vacuum around the base of cylinder 2 in proximity to the atomizing nozzle by reason of the air admitted through the cylinder perforations 2.

-At the same time the stream continues to be directed upon the tip of the electrode and thereby serves to inhibit carbonizing.

Itis important to note that, with the exception of the relatively minute stream admitted through vacuum breaker orifice 9, no air is admitted into the primary combustion zone behind nozzle I, at which point the oil fed through tube I4 is mechanically atomized to form a fog within the perforated cylinder. All of the air admitted into the primary combustion zone enters immediately ahead of nozzle 1 and is directed toward the axis of the cylinder, in line with which the atomizing nozzle is located. Furthermore, the air admitted under the static head built up in the annular compartment surrounding the perforated cylinder is admitted in a direction normal to the direction of oil discharge. For this reason the fog produced by atomizer l is subjected to a bombardment of primary combustion air from 'all sides and traveling in a direction normal to the axis of oil discharge. Expressed somewhat differently, the air discharged into the primary combustion space under a predetermined head is seeking the core of the fog produced by mechanical atomization. There is no tendency for the primary air to simply entrain the fuel particles issuing from the atomizing nozzle without actually mixing, as is the case where the primary combustion air is admitted through openings that are inclined with reference to the axis of oil discharge and/or which lie behind the atomizing nozzle.

Because of the absence of any pressure head behind the point of atomization and the absence of any air current in a direction away from the point of mechanical atomization, a thorough and intimate mixture is developed within the primary combustion space inside perforated cylinder 2.

The flame propagation resulting from this improved manner of carburetion may be likened to the action of jet propulsion. Inasmuch as, to a greater or lesser extent, there is always a negative pressure in the secondary combustion space 20 which communicates: with the stack through which the waste gases are passed, the force of the primary combustion within the perforated cylinder is quite sufficient to propagate the flame into the secondary combustion chamber 20 without the aid of any pressure head or entrainment by air currents directed at a forward inclination to the oil discharge axis.

Inasmuch'as every particle of air mixes thoroughly and intimately with the mechanically atomized oil particles, there is no need whatsoever for excess air to secure efficient-combustion'. The premixing within the gasifying or carbureting chamber maybe adjusted.- for maximum efficiency by varying. the static pressure within theamiular. chamber surrounding the perforated cylinden. Efficiency is. further enhanced by reason of the factthat the said static pressure may be adjusted entirely independently of the .pressure behindthe oil. discharge. which is mechanically atomized. at the nozzle: T, a: control obviously incapable of. attainment where. atomization by air as distinguished from mechanical atomization is utilized.

The combustion head i and perforated cylinder 2 likewise perform the important function of pre-heating the air before admission into the primary combustion space. The removable plug 4 permits ready removal of the nozzle and electrode assembly without dismantling the unit. Necessary adjustments may therefore be made more quickly and easily.

Not only is excess air, which for the many reasons heretofore outlined cuts down efficiency of operation tremendously in proportion to the quantum of excess air utilized, eliminated by utilizing the principle of operation described herein, but the waste due to any portion of the oil passing through as oil vapor is likewise e1iminated by the positive and thorough mixing obtained. It should be noted that all of the air for combustion is supplied in the primary stage and that neither the air supply nor the method of supplying it performs any function in connection with atomization of the oil. This is in contradistinction to methods and apparatus wherein only enough air is supplied in the primary stage to effect oil atomization and air needed for combustion is furnished in the secondary stage.

The chamber formed by the perforated cylinder should be as small as possible commensurate with obtaining thorough and intimate mixing of the oil and air. Inasmuch as the cylinder perforations function as air metering ports and the quantity of combustion air delivered is dependent upon the number of ports and the pressure head behind them, the cylinder must of course be large enough to supply the required number of perforations.

The thorough mixture forms a combustible which eliminates any need for dependence upon a secondary combustion chamber for reflected heat to insure complete combustion and, as hitherto explained, the propagation of flame is assured by the expansion force of ignited combustible, this force acting in the direction of the secondary chamber because the rear of the primary chamber is closed by the nozzle plug. The effect of power or jet propulsion is thus obtained.

While I have described a preferred embodiment of the invention and specific structure for performing the improved method described herein, it will be understood that the invention resides primarily within the novel concept disclosed, and for that reason I wish to be limited only within the scope of the appended claims.

What I claim is:

1. Apparatus for burning liquid fuel comprising in combination a draft tube, a fuel delivery tube inside the draft tube, means for forcing air under pressure through the draft tube and fuel under pressure through the fuel tube, a cylindrical housing secured to the end of the draft tube in direct communication therewith, an open-ended perforated cylinder within said housing secured in spaced relation thereto forming an annular passage around the cylinder communicating with the draft tube, said cylinder being in axial alignment with the draft tube, means closing the open end of said passage, a removable closure for the inner end of said perforated cylinder, and a mechanical atomizing nozzle secured to the end of the fuel delivery tube positioned by the removable cover inside said cylinder in alignment with the axis thereof.

2. In an oil pressure atomizing burner, an atomizing nozzle, adjacent ignition means, means for pumping oil through said nozzle, an air tube, fan means for supplying air to said tube to meet the oil adjacent the nozzle, a tubular cylinder provided with many perforations closely spaced both circumferenti'ally and axially and generally distributed over substantially the whole cylindrical surface, said cylinder being positioned within the air tube to form a jacket, the jacket being connected to the fan for receiving substantially all of the air supply to be directed through the cylinder perforations in many small pressure jets, said nozzle being positioned axially to discharge directly into the rear portion and generally lengthwise of the cylinder across such jets, the perforated part of said cylinder extending from the place of oil discharge and far enough inside the air tube to substantially complete oil and air mixture inside the cylinder for both starting and continuing a substantial part of the fuel combustion in said cylinder before the mixture leaves the cylinder.

3. In an oil pressure atomizing burner of the kind having an oil pressure atomizing nozzle, adjacent ignition means, power mechanism to pump the oil through the nozzle at a predetermined constant pressure, a fan to supply air, an 'air tube to direct air from the supply fan to meet the oil adjacent the nozzle, the combination of a tubular cylinder, provided with many perforations closely spaced both circumferentially and axially and generally distributed over substantially the whole cylindrical surface, said cylinder being positioned inside and spaced from the air tube to form a jacket, the jacket being connected to the fan, for receiving substantially all of the air supply to be directed through the cylinder perforations in many small pressure jets, said nozzle being positioned axially to discharge directly into the rear portion and generally lengthwise of the cylinder across such jets, the perforated part of said cylinder extending from the place of oil discharge and far enough inside the air tube to substantially complete oil and air mixture inside the cylinder for both starting and continuing a substantial part of the fuel combustion in said cylinder before the mixture leaves the cylinder.

MORRIS SHERMAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,373,190 Good Mar. 29, 1921 1,379,178 Good May 24, 1921 1,413,113 Good Apr. 18, 1922 1,450,229 Robinson Apr. 3, 1923 1,725,510 Fiske Aug. 20, 1929 1,891,444 Reichhelm Dec. 20, 1932 1,923,614 Clarkson Aug. 22, 1933 1,953,483 Higinbotham Apr. 3, 1934 2,072,731 Crosby Mar. 2, 1937 2,078,021 Rodler Apr. 20, 1937 2,221,519 Jones et al. Nov. 12, 1940 2,398,654 Lubbock et al Apr. 16, 1946 2,402,971 McCollum July 2, 1946 2,411,048 Logan Nov. 12, 1946 FOREIGN PATENTS Number Country Date 259,044 Great Britain Oct. 7, 1926 315,252 Great Britain July 10-, 1929 791,271 France Sept. 23, 1935

Images