US1918326A - Burner - Google Patents

Description

W. DOBLE July 18, 1933.

BURNER Filed March .6, 1931 III I i mmvron. War/ en flab/e M 7 ATTORNEYS.

is capable of Patented July 18, 1933 UNITED STATES PATENroFFica I I 953w, canu-oama Application flled'March 6,

This invention relates toa burner wherein a forced draught of high velocity air is employedto furnish a combustible mixture of air and a fluid fuel, such as gasoline, engine distillate, fuel oil, kerosene, powdered coal and the like.

The invention is particularlyconcerned with the formation of a homogeneous fuelair mi'xtureto the end of securing very efiicient Combustion from burners ofthe type in which the low pressure created by a high velocity air stream in a suitable conduit, as atthe throat of a venturi, is utilized to. draw a fuel into the air stream rushingv through the Venturi. Present burners of this type do not furnish a completely homogeneous mixture, ,and, as a result of this,

the fire burns unevenly, with poor combustion efiiciency and considerable noise. 1

It is in general the broad object of the present invention to devise a burner which providing a substantially homogenous fuel-air mixture to the end of promoting combustion efficiency, reducing the noise of the fire and fuel consumption.

The invention ous features and o jects, some of whichwith the foregoing will be set forth at length in the following specification wherein I have outlined the preferred form of the burner of my invention. 1

In the drawing, Figure 1 is an elevational view, partly in cross section, of a burner embodying my invention. I, I

Figure 2 is aview looking in the direction of flow of air in Figure 1, the view illustrating the construction and positioning of certain of the elements of the burner.

Figure 3' is a section taken alongthe line- 33 of Figure 1. i t

Figure 4 is a section taken along'the line 4-4 of Figure 1. p

My invention comprises the discovery that the heterogeneous character of the fuel-air mixture secured by aspiratingfuel into a high velocity air stream is largely due to the resistance or apparent reluctance of the air stream to admit the fuel and the provision of means for overcoming this difiiculty lowering the rate of ossesses .other advantagean air-fuel for successfully 1931. Serial No. 520,619.

whereby a homogeneous fuel-air: mixture is secured. Thus, a burner employed prior to this invention usually included a Venturi tube through which air was rapidl passed. A fuel supply pipe extended into t e throat of the venturi so that the low pressure at the throat drew fuel throughthe-pipe'into the air stream 'in the Venturi. This burner pro-' vided an air-fuel mixture suitable for subsequent ignition. However, the burnin was 5 uneven,-noisy and not of a very hig efiiciency. I have discovered that by causing the formation of a low pressure area, substantially free of eddy currents, adjacent to and immediately about the dischar e of the fuel supply conduit, the burning o the fuel is even, thenoise is diminished and. the com bustion improved. This low pressure area formation, which I termcavitation, can vbe visualized as the forming. of aihole in the rushing air stream into which the fuel enters' The relatively fast moving air stream confined in the conduit resists the attempted insertionof the fuel. By causing cavitation to occur in this stream, which has a velocity of the order of. 100 miles per hour, and introducing the-fuel, orrrich fuel-air mixture as is done with the embodiment of the invention disclosed, into the cavity formed, the incorporation of the fuel in the air stream is so accomplished that mixture is secured which is truly homogeneous. In the apparatus which I have developed carrying out my invention, 55 an air stream is furnished under pressure from a suitable source asfrom a blower 7 through a conduit 8 which includes a Ven turi section 9. The Venturi section includes an upstream portion 11 and a downstream '90 I quireinents dictate that the Venturi tube 16 be disposed in a horizontal position.

Fuel is supplied to the fuel pipe 18 from a float chamber, not shown, or other source Y of fuel supply, by means of a delivery pipe 21 which extends through a stufiinggland 22 provided in a sump member 23. The member 23 is formed to provide a sump 24 in which excess fuel from the delivery pipe 21 can collect and be removed through a drain 25.

The fuel delivery pipe and the float chamber are preferably located a considerable distance away from the Venturi 16 in order to lessen the absorption of heat by the fuel, as in practise the temperature of the Venturi 16 is relatively high. The problem of feeding fuel to the pipe 21 also indicates that the pipe should be as low as possible; that is, below the Venturi 16. The sum of these general requirements is that the delivery pipe 21 ispreferably a ertical tube located considerably below and at right angles to the horizontal Venturi section 9. This arrangcment, however, affords deleterious results unless the burner of my invention is employed. v I

Means are provided for diverting a portion of the air stream in the conduit 8 and these means include a scoop member 26 formed upon the conduit to direct air from the conduit through a duct 27 and the sump 24. The delivery pipe 21 extends within the fuel pipe 18, the fuel pipe preferably having a Venturi contour and the pipe 21terminating at the throat portion 28 of the fuel pipe 18. The withdrawal of fuel from the float chamber and incorporation withthe air stream is aided by diverting a portion of the airstream from the conduit to pass through the Venturi fuel conduit. The three Venturi tubes, thus provided, enable fuel to be aspirated readily into the air stream and allow fuels of high specific gravity to be burned successfully.

In operation the apparatus so far described is not capable of furnishing an airfuel mixture of the homogeneity desired for subsequent ignition as upon issuance from the Venturi section 9. By means of my discovery, however, this apparatus can be made suitable for furnishing the desired homogeneous mixture. To this end, therefore,

means areprovided for operating upon the air stream rushing over and about the discharge of the fuel pipe'18 where it opens into the air stream to create a low pressure area so that a hole or cavity is formed inthe air stream into which the fuel enters without meeting with or having to overcome the resistance from the high velocity air stream.

In the preferred form of the apparatus here disclosed I provide a stream lined body 31 to which I usually apply the term of splitter. This body, as is shown in Figures 1 and 2, is'formed within the Venturi tube 16 to extend downwardly to the edge of the Venturi tube ahead of the outlet of the conduit 18. The body, as is shown'in' Figures 2 and 4, is stream-lined and tapered upwardly to an apex at about two-thirds the throat diameter of the Venturi tube 16. This effects a splitting of the air stream passing over and about the outlet of the conduit 18 so that a cavity is formed in the air stream on the lee side of the body. The fuel is sheared from the fuel stream in the conduit 18 to enter uniformly into the air stream to furnish finally an air-fuel mixture of a very homogeneous character. The formation of the cavity in the stream is accomplished without the creation of, the undesirable eddy currents which were present in the burners heretofore utilized.

It is to be noted that the body 31 is not only stream lined to split the air stream to form a cavity over and about the point of fuel introduction but is also stream lined as to allow'for a quick convergence of the solute necessity since the introduction of.

fuel into the air stream can be effected without it, particularly on lighter fuels. However, the utilization of the splitting means or body 31 is necessary to secure a homogeneous air-fuel mixture instead of the otherwise heterogeneous, uneven and uncertain mixture supplied by present burners.

It is to be understood that my invention can be embodied in other forms than I have here disclosed within the scope of the claims.

I claim: I

1.'In a burner includinga conduit having a Venturi section through which an airstream is passed, a Venturi tube positioned in the conduit ahead of the Venturi section and adapted to discharge air passing therethrough substantially at the throat portion of the Venturi section, a fuel conduit extending through the conduit and opening into the Venturi tube adjacent the throat.

thereof, the fuel conduit serving to convey fuel into the Venturi tube, and means for tion for subsequent ignition.

2. In a burner including a conduit having a Venturi section through which an air.

stream is passed, a Venturi tube positioned in the conduitahead of the Venturi section and adapted to discharge air passing therethrough substantially at the throat ortion of the Venturi section, afuel c'on' uit extending through the conduit and o ening into the Venturi tube adjacent t e throat thereof, the fuel conduit serving to convey fuel into the Venturi. tube, and a stream lined member positioned in the Venturi mixing tube. 4

andair mixing device compristube adjacent the fuel conduit opening for effecting cavitation of air passing through the Venturi tube substantially over the fuel conduit 0 ening in the Venturi tube where by a su stantially homogeneous air-fuel mixture is supplied from the Venturi section for subsequent ignition.

3. A- fuel and air-mixing device comprising a Venturi tube, a source of air under pressure for causing a flowof air through said Venturi tube, a source of fuel, a fuel -nozzle connected with said source'of fuel,

a mixing tube into which said fuel nozzle projects a stream of fuel; said mixing tube receiving air from said source of air under pressure; said mixing tube projecting a fuel and air mixture into the throat of said Venturi tube substantially at right angles .to the flow of air through said Venturi tube, said Venturi tube being provided with a protuberance arrangedin its inlet end and ex- 1 tending into its throat to shield the fuel mixture from themixing tube which enters throat wherein the velocity is high and the pressure is low, a second fuel and air-mixin substantially a right angle to the motion'of tube communicating with said throat at I fuel and air passing through the said first mixing tube, a deflector arranged in the inlet end of said first mixing tube and extending to the aperture in the throat of said first mixing tube, where the fuel and air mixture from. the second mixing tube enters the first'mixing tube, said deflector being arranged to guide the air which enters said first mixing tube such that the flow of air and fuel mixture issuing. from the second mixing tube will be subjected to the flow of air in the throat of the first mixing tube graduallyas it crosses the throat of the first turi tube-and having a width at the throat surface of the Venturi tube substantially equal to the width of the fuel and air mix, ture issuing from themi'xing tube, and said bafiie extending across the throat of said Venturi tube and tapering in width in a direction across said Venturi tube to substantially no thickness at the end of the baffle far from the inlet aperture for the fuel and 7 air mixture issuing from the mixing tube.

6. A flu d mlxmg device comprlsmg a first tube through which fluid passes, a second 7 tube through which fluid passes, saidsecond tubedischarging fluid into said first tube, the flow ofvfluid in said second tube being substantially at rightangles to the flow of fluid in said first tube, a tapered baflle arranged in said first tube and having a width at the inner surface of said first tube substantial}? equal to the width of'the "openin in said rst tube throughwhich the om said second tube passes, said fluid bafile extending substantially across said first tube and tapering in width in'a direction across said first tube to substantially no width. 7,

- I WARREN DOB'LE."

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