US2497282A - Heating device and combustion process - Google Patents

Description

Feb. 14, 1950 R. J. WALLER HEATING DEVICE AND COMBUSTION PROCESS 2 Sheets-Sheet l INVENTOR :cd M

ATTORNEYS Filed Nov. 23, 1944 Feb. 14, 1950 R. J. WALLER HEATING DEVICE AND COMBUSTION PROCESS 2 Sheets-Sheet 2 Filed Nov. 25, 1944 Patented Feb. 1 4, 1950 HEATING DEVICE AND COMBUSTION PROCESS Richard J. Waller, Bridgeport, Conn, assignor to Bridgeport Brass Company, Bridgeport, Conn, a corporation of Connecticut Application November 23, 1944, Serial No. 564,351

7 Claims.

This invention relates to heating devices, and more particularly to devices designed particularly for use of liquid fuels.

An object of the invention is to provide a simple type of heating dcViQ that may be made of com paratively small dimensions so that it may be readily placed in a small compartment or chamber so that the heat derived from the device may be applied Where it will do the most good.

Another object of the invention is to provide a device adapted to consume various types of liquid fuels such as gasoline, oil or the like very efficiently.

A further object of the invention is to provide controlled means for feeding oxygen or oxygencontaining gas necessary for the efiicient combustion of the fuel utilized.

Another object of the invention is to provide means for feeding a component of the air or oxygen-containing gas necessary for combustion as what may be termed an entraining gas and also to provide means for feeding a second component of the air or oxygen as what may be termed a processing gas.

A further object of the invention is to provide a device of this character with a burner surrounded by refractory means so that the combustion of the fuel-air mixture emitted at the burner will cause the refractory means to become incandescent.

It is another object of the invention to provide an adjustable construction of the burner so that the velocity of the emitted gaseous gas-fuel mixture may be adjusted to create the desired degree of incandescence of the refractory means with highly efficient fuel consumption.

Another object of the invention is to provide a device of this character that will afford practically instantaneous control of the time of shutoff. In other words, to provide a device that will not provide any objectionable or appreciable time lag between the time of shut-off of fuel and air and the time of cessation of flow of residual fuelair mixture in the mixing chamber or chambers of the device.

It has been found that it is necessary to maintain determined or critical relationship in operation between the volume of the entraining air or oxygen-containing gas and the processing air or oxygen-containing gas if high efficiency is we attained.

An object of this invention is to provide structure capable of meeting the foregoing requirement.

It has also been found that the device requires expansion of the atomized and processed fuel and maintenance of controlled temperatures in certain portions of the expansion region in order to insure complete gasification and efiicient combustion of the gasified mixture. It is an object of this invention to provide means for maintaining such control.

Another object of the invention is to provide means for utilizing part of the heat of combustion for maintenance of the controlled temperatures.

Another object of the invention is to provide a novel method of combustion of liquid fuels wherein substantially complete gasification of these fuels occurs prior to combustion, and a process which is safe in operation, practical and dependable, and of providing apparatus capable of meeting all the foregoing requirements.

Yet another object of the invention is to provide simple small devices for the purposes outlined that may be utilized singly or in batteries of units so that one or any number of such units may be utilized at a time for the production of heat where necessary.

To the accomplishment of the foregoing and such other objects as may hereinafter appear, this invention consists in the novel method, construction and arrangement of parts hereinafter to be disclosed and then sought to be defined in the appended claims, reference being had to the accompanying drawing forming a part hereof, which shows merely for the purposes of illustrative disclosure a preferred embodiment of the invention, it being expressly understood, however, that changes may be made in practice within the scope of the claims, without digressing from the inventive idea.

In the drawing, in which similar reference characters denote corresponding parts:

Fig. 1 is a longitudinal section of the device;

Fig. 2 is an end elevation of the device of Fig. 1 viewed from the right of the latter figure;

Fig. 3 is a vertical section taken along line 3-3 of Fig. 1 and viewed in the direction of the arrows;

Figs. 4, 5 and6 are vertical sections taken respectively along lines 4-4, 5-1-5 and 6-8 of Fig. l and are viewed in the directions of the respective arrows; and

Fig. '7 is a side elevational view of the device with conventional fuel and air sources attached.

Referring to the drawing, the heating device H comprises generally; blender parts A and B wherein fuel is entrained, processed and blended with oxygen-containing gas such as air, an ex pansion chamber C connected with the blender parts by a diverging tubular portion D and into which the blended fuel and air is discharged from the blender parts, an adjustable burner nozzle E arranged at the outlet from the expansion chamber, and refractory material in the form of a cup or shell F arranged in conjunction with the burner nozzle E and the expansion chamber C all for purposes to be presently described.

The blender part A is a casting ID of suitable metal such as brass or the like. The casting I is provided with a port or passage 1 I extending longitudinally therethrough and opening through the threaded end or nipple 42, which is adapted to be coupled to an air compressor P (Fig. 7) for feeding air under pressure into the port or passage II. This casting l0 has an annular chamber 13 machined in its opposite end and connected thereto is port or passage l4 which is in turn connected to port or passage l5, which joins the port or passage l I. The access between ports or passages ll, 15 and I4 is controlled by the adjustable needle valve construction it.

The second blender part or member B likewise is preferably a casting IQ of metal similar to that of part A. This casting I9 is adapted to be secured to the forward end of member 10 by means of a suitable joint and weld or in other suitable way. This member IQ is provided with an intermediate central chamber 2! which is connected to chamber l3 by means of a plurality of ports or passages 22. An extension 23 of the part H3 formed or provided with a, nozzle 24 is positioned to extend through an end wall of member 19 so that the nozzle orifice 25 forms a continuation of port or passage I I. The ports or passages 22 are arranged substantially in a concentric circle around the orifice 25.

The nozzle orifice 25 is positioned adjacent and above the orifice 26 of a nozzle 21 which has a pipe connection 29 with a suitable tank or receptacle 30 (Fig. 7) for the gasoline, kerosene, fuel oil or other fuel. This forms an atomizing construction so that when air under pressure passes through port or passage H the fuel will be withdrawn from the tank or receptacle 3;. and atomized and forced into the divergent or flared or horn shaped chamber D in a member 34. This member 34 preferably of heat conducting material such as brass is suitably attached to the forward end of member 13. This divergent expansion chamber D communicates with a cylindrical expansion chamber C having an end wall or deflection surface 35 on which is mounted the burner element E. The end wall 35 in the embodiment shown is substantially a plane surface. The burner element may be of any conventional type. In the embodiment shown, it includes the burner tip 38 which is in the form of a circular disk having a cylindrical portion 31 connected threadedly for adjustment in a plug 38 carried suitably in the end wall 35. The cylindrical portion 31 has the opening 39 and is provided with a plurality of ports or passages 40 communicating with the spaces or orifices 4| between the burner tip 36 and the plug or complementary member 38. These last mentioned parts are all located centrally within the shell or cup F of refractory material which becomes incandescent when heated. This shell or cup F is provided with one or a plurality of ports or passages 42 in its rear wall 43 near the burner tip 36 and adjacent the outlets 4! for a purpose to be described later. The member 34 is provided with suitable wings or flanges 45 or equivalent means for attachment of the device to fixed parts. The member 34 may be unitary or made up of multiple sections. It is of heat conducting material.

The operation of the device, in general, is simple. The air pressure from source P is turned on and the atomized fuel is forced into the chambers D and C and through the ports or passages 39 and 40 and the openings 4| where the fuel is ignited by any suitable ignition means such as a spark, flame or the like (not shown). As the temperature of the shell or cup F member increases and as the fiame or products of combustion pass through the ports or passages t2, the end wall or hot plate 35 of chamber C is substantially raised in temperature, at which time the eiiiciency of the device is increased by opening the needle valve 16 which provides additional air in chambers 2!, D and C. The additional air or oxygen-containing gas then delivered through the openings 22 is in the form of an envelope about the region of atomization. This so-called processing air aids in securing greater atomization of the fuel and greater efficiency in opera-. tion and greater heat. In the device as illustrated designed for a 10,000 B. t. u. per hour capacity, efiiciency of combustion utilizing ethyl gasoline as fuel and based upon CO2 content of the exhaust gases has by experiment been found to be of the order of from about 94 to 99.1%. Very high elficiency of combustion is thus a result of the structure shown.

The heater device is started by use of entraining air. When entraining air only is being used the amount of fuel raised through the fuel orifice 2G is at its maximum and the mixture of atomized fuel and air can be described as rich. This is the starting condition. When combustion has started sufficiently for the use of processing air the amount of air passing through the entraining air opening 25 is automatically reduced thus re ducing the amount of fuel lifted through the fuel orifice 26 and thus automatically reducing the richness of the mixture of fuel and air and placing the entire combination in its normal functioning condition. This contributes to the high efficiency.

The construction of the heating device as a whole is such that it may be made of comparatively small dimensions so that it may be readily placed in a small compartment or chamber so that the heat from the burner E and the incandescent member F may be directly applied where it will do the most good. Single units or banks of such units may be used.

In connection with the operation of the device it appears necessary to maintain at the point of emission of the mixture of air orother oxygencontaining gas and fuel, namely at the orifices 4| of the burner E, a velocity which will maintain on the refractory shell F the required incandescence. The required incandescence in the device described for satisfactory or standard operation is in the neighborhood of 2200 F. when air is supplied at approximately 10 lbs. per square inch pressure. This temperature may be made to vary by adjustment of the burner E. The velocity mentioned is that in the nozzle or emission area. If the refractory shell F is porous, then it seems that the velocity of the gases issuing from the emission area can be somewhat higher. On the other hand, if the refractory shell is less porous, velocity it seems can be somewhat less. The particular velocity necessary, therefore, depends upon the nature of the refractory material. It is an important aspect of the invention, however,

to provide means to maintain .or adjust the velocities to achieve optimum burning conditions. This is accomplished in the disclosed device by the fact that the burner part 36 is adjustable so that the size of openings 41 may be varied. Other suitable adjustment may be provided.

.Another important aspect of the invention is the maintenance of a determined ratiobetween the entraining gas and the processing gas. .In practice, it has been found that best results are obtained when the relationship between the volume of entraining .gas and processing gas is of the order of to 60. This can be conveniently termed the entraining processing ratio. While this ratio at the present is found to be .of the order of 40 to 60, it must-be understood that other ratios are possible. In the embodiment shown, theratio may be varied by adjustment of the valve 18. Other suitable means for adjustment maybe provided.

.A further important aspect of the invention is that successful operation and maximum efiiciency depends upon maintenance of an elevated predetermined temperature at the wall 35. This wall or -defiecting surface may be conveniently also tenneda hot plate. The exact temperature of the .hot plate is somewhat indeterminate but experimental measurement of the tempera ture in the space 65 has shown that if such temperature is maintained in arange lying-approximately between 450 and 950 F., the hot plate" will be sufficiently vheated. In operation of the embodiment shown under design conditions the temperature range in the space hasbeen found to be approximately 650 to 750 I. when the fhot plate is sufiiciently heated.

It will be understood, of course, that the wall or hot plate 35 is part of the heat conductive member 34 so that the walls of member 34 in turn become warmed by heat conduction. It appears necessary in other words to maintain the .walls of member 34 in the region of the deflection plate 35 at elevated temperatures to insure complete gasii'ication of the fuel prior to its combustion. Thus by maintaining the hot plate 35 within predetermined temperature ranges as outlined herein. it has been found that the other walls of the member 34 receive the required amount of heat by conduction from wall .35 and otherwise, to insure such gasification of the fuel.

Another important aspect of the invention lies in providing means to prevent the gasesdefiected by the hot plate 3.5 from moving back to cooler portions of the member 34. It will be noted that the expansion chamber C increases abruptly in diameter relative to the largest diameter of the divergingportion D. The shoulder 50 thus provided serves as additional deflector means.

It is well known that when a fluid hits a har surface with considerable velocity in a direction more or less perpendicular to the surface, the fluid spreads out in all directions in a thin sheet. If the surface is turned back, as in a cup or a glass, the water, for example, strikes the bottom inside the glass, spreads in a thin sheet to the side walls of the glass, turns and follows along the surface of the sides and comes out of the glass in a cylindrical sheet.

Consider now the situation in the chambers C and D. The main fluid stream F of atomized fuel impinges on the portion of the-hot plate :35 in the region surrounding the orifice 39 in a direction more or less perpendicular to .the said plate and is deflected. The deflected stream spreads ina thin sheet radially in all directions toward the walls of the chamber C as denoted by the arrows G. Then in turn the streams (1 turn and follow the surface of the cylindrical chamber .0 back away from the hot plate 35 but, a .short distance away from the hot plate, they encounter the shoulder .56 which deflects them inward toward the oncoming stream F of atom.- ized fuel. The latter having considerable velocity drags streams G back toward the hot plate .35. This completes one round of the circulation cycle. In the .course of this circulation, streams .G of fuel-air :mixture have picked up heat by scrubbing the walls 35 and 5| of the hottest part of the mixing chamber C. Also, when they meet the freshly arriving fuel and air stream F emerging from the end of chamber D they impart some of their heat to it, thus preheating it before it reaches the hot plate .35. Inasmuch as the drift velocity of the air-fuel mixture, as a whole, is low compared with the circulation velocity, a given parcel of fuel-air mixture may complete a considerable number of cycles of circulation before passing through the burner orifices Al. What happens to a particular parcel of fuel air mixture would be hard to say. Some portion of it may pass out through the burner orifices :in its first contact with the hot plate 35. When starting cold, and before operating temperatures have been reached. any fuel and air mixtures passing through the burner orifices M after first contact with the hot plate 35, probably Contains some unvaporized fuel. However asthe hot plate 35 and adjacent side walls of the chamber C increase in temperature, more and more heat is carried by the circulating currents G to the oncoming fresh fuel and air stream F until, under operating conditions, the freshly arriving fuel and air mixture heated sufficiently to effect complete vaporization or .gasification before it reaches the hot plate 35. All fuel and air adjacent the burner orifices 39, 4! is then in a completely gasified state. It is thus seen that the deflection shoulder 50 is apparently of importance.

Another aspect of the invention lies in proper relationship of the atomizing orair orifice 25 with respect to the fuel orifice 26. It has been found by a series of experiments that stability of operation is best when these orifices 25 and 28 are arranged in proper relationship to each other and are of proper diameter relative to each other. For example, with a heater devised for 10,000 28. t. u. per hour capacity, with air pressure supplied at 10 lbs. per square inch and utilizing ethyl gasoline as fuel, optimum efiiciency of combustion occurs when the air orifice 25 has a diameter of .040 inch and the fuel orifice 26 has a diameter of .036 inch. With thesediameters, the respective axes of the orifices should be co-planar and cross each other at substantially right angles. The crossing point Y of these axes may be conveniently designated the point of orifice combination. The outlet end of air orifice 25 should lie .024 inch to one side of this point Yand the outlet end of the fuel orifice 26 should lie .014 inch below this point Y. These distances with respect to the point may be conveniently termed the horizontal distance and the vertical distance. While these particular distances and orifice diameters are given as ones producing optimum conditions it must be understood that variation in such distances and in orifice diameters are contemplated. In fact, experiment has shown that stability of operation may be secured with horizontal distances varying from .005 to .024

- inch and vertical distances from 0.000 to 0.015

inch with the particular orifice diameters given. With different orifice sizes, tests indicate that stability of operation the horizontal distance should not exceed 150% of the diameter of the fuel orifice and the vertical distance should not exceed 80% of the diameter of the air orifice. In the embodiment shown, the fuel orifice 26 and the air orifice 25 are shown in the relationship indicated hereinabove producing optimum efficiency. It should be understood, however, that a structure permitting variation in orifice diameters and in orifice positions is contemplated and to be regarded as within the scope of this invention. It will be noted that the fuel nozzle 21 is mounted for vertical adjustment. The entraining air nozzle 25 can be similarly made adjustable or in any other suitable manner, thus providing means for adjusting both the aforesaid vertical and horizontal distances.

It will be noted further from Fig. l of the drawing that holes $2 are arranged in a portion of the refractory shell F in the region of curvature 69 so that ledges or shoulders 62 are provided that lie in the path of the gases emitted from the orifices M of the burner E. These shoulders 62 are of importance because they form deflecting surfaces or means that serve to break up the stream of gases flowing substantially normal to these surfaces into streams, one of which flows inwardly through the holes 42 while others flow outwardly. The inwardly flowing gases are either in a state of combustion or have been heated because of their close contact with the shell F in its region of greatest incandescence so that in circulating through holes 42 and in the chamber 65 they serve to increase the heating effect upon the wall 35 and thereby contribute to the highly enicient and stable operation of the device.

It will be seen, therefore, that the device provides means for atomizing and processing liquid fuel with oxygen-containing gas, means for permitting expansion of the so atomized and processed fuel, means for effecting complete gasification of the atomized and processed fuel and means for burning the completely gasified fuel externally of the means in which expansion occurs. It will also be noted that the device provides means for utilizing a portion of the heat of combustion in insuring the substantially complete gasification. It also provides means for adjusting the velocity of the gasified fuel emitted through the burner. It also provides means for varying the ratio of the processing and entraining gases, and various other structural features whereby combustion with utmost efficiency is obtained.

While a specific embodiment of the invention has been disclosed, it is to be understood that variation in structural detail within the scope of the appended claims is contemplated. There is no intention of limitation to the exact details shown and described.

What is claimed is:

1. In a device of the character described, means for atomizing liquid fuel with oxygen-containing gas, means for treating the atomized fuel with additional such gas in the region of atomization, means for proportioning the volumes of atomizing and treating gases, said device having chambers in succession into which in succession a mixture consisting of atomized fuel and atomizing oxygencontaining gas and treating oxygen-containing ga in proportions controlled by said proportioning means are delivered, heating means for the final one of the chambers, and turbulence creating means in the final one of the chambers, said chambers, heating means and turbulence creating means effecting expansion of said mixture in said chambers, and its substantially complete homogeneization into a homogeneous gaseous product, and means for burning the homogeneous gaseous product only subsequent to the completion of homogeneization, and externally of said third-named means.

2. In apparatus for the combustion of liquid fuel, means for entraining and atomizing said fuel with an oxygen-containing gas, a wall adjacent said means having passageways arranged for supplying an additional quantity of oxygencontaining gas to the entrained and atomized fuel in the region of atomization and entrainment, adjustable valve means for proportiom'ng the volumes of the atomizing and entraining oxygencontaining gas and the additional quantity of oxygen-containing gas, said apparatus having a divergent chamber into which the entrained and atomized fuel is delivered and an expansion chamber directly adjacent said divergent chamber whose cross sectional area increases abruptly with respect to the largest cross sectional area of said divergent chamber, said expansion chamber having a deflecting surface, burner means adjacent the said surface through which a substantially inseparable gaseous mixture of gasified fuel and oxygen-containing gas from said expansion chamber is discharged for combustion, and refractory means adjacent the said burner means, said refractory means having at least one opening in communication with said deflecting surface to permit transmission of part of the heat of combustion thereto for maintaining the said surface heated during combustion.

3. That improvement in the process of combustion of liquid fuel comprising the steps of entraining and atomizing said fuel with an oxygen-containing gas, treating the so entrained and atomized fuel with a determined quantity of processing oxygen-containing gas by delivering said quantity under pressure as an enveloping gas about the region of atomization, expanding the so treated fuel-gas mixture and causing turbulence thereof to efiect substantially complete homogeneization of the mixture of fuel and gases into a homogeneous gaseous product prior to combustion, and thereafter burning the so homogeneated gaseous product.

4. That improvement in the process of com bustion of liquid fuel comprising the steps of entraining and atomizing said fuel with entraining oxygen-containing gas, treating the atomized and entrained fuel with a quantity of processing oxygen-containing gas by delivering said quantity as an enveloping gas about the region of atomization, maintaining a predetermined ratio between the volumes of said entraining and processing gases, expanding the so treated fuelgas mixture in confined zones and causing turbulence thereof, maintaining a portion of said zones at substantially elevated temperature and effecting substantially complete homogeneization of the mixture of fuel and gases into a homo geneous gaseous completely combustible product prior to combustion and thereafter burning said homogeneous gaseous product externally of said confined zones.

5. That improvement in the process of combustion of liquid fuel comprising the steps of entraining and atomizing said fuel with entraining oxygencontaining gas, treating the entrained and atomized fuel with a quantity of processing oxygen-containing gas in the region of atomization, maintaining a predetermined ratio between the volumes of the said entraining and processing gases, delivering the resulting fuelgas product as a stream to an expansion zone, and from there directly to a second expansion zone of increased sectional area over the largest sectional area of the first-named expansion zone, impinging the stream in said second zone against a deflection surface, and maintaining said surface and said second zone at elevated temperatures, whereby substantially complete homogeneity of the fuel-gas product prior to its combustion is effected and burning the resulting homogeneous gaseous product exteriorly of said second zone.

6. That improvement in the process of combustion of liquid fuels comprising the steps of atomizing such fuels and effecting a gaseous mixture of such atomized fuels and oxygen-containing gas, effecting expansion of the gaseous mixture while it flows in a unidirectional stream, abruptly deflecting said stream while maintaining a temperature substantially above that of the stream in the region of deflection, redeflecting the deflected stream to prevent its being cooled and to provide additional circulation for the stream whereby substantially complete homogeneization of the fuel-gas mixture of the stream into a homogeneous gaseous product is effected, burning the homogeneous gaseous product subsequent to its homogeneization, and utilizing a portion of the heat of combustion of said homogeneous gaseous product to maintain the temperature in said region of deflection which is substantially above that of the stream in said region.

7. In a device of the character described, means for atomizing liquid fuel with oxygencontaining gas, means for treating the atomized fuel with additional such gas, said device having a divergent chamber and an expansion chamber directly following the divergent chamber and into which chambers in turn a mixture consisting of components of atomized liquid fuel and atomizing oxygen-containing gas from said firstnamed means and added treating oxygen-containing gas from said second-named means is delivered, and turbulence creating means in said expansion chamber for said mixture whereby with the heating of said chamber, said mixture in turbulence becomes a stable homogeneous completely gaseous product whose components 10 are substantially inseparable therefrom, means for burning said gaseous product externally of said expansion chamber, and means for utilizing a part of the heat of combustion of said gaseous product to warm a portion of said expansion chamber and provide the required heat for the formation of said gaseous product, said utilizing means including a refractory shell having walls, and a burner nozzle surrounded by walls of said shell, said shell having a portion defining a space between said expansion chamber and a wall of said shell, and said last-named wall having openings communicating with said space, and said openings being positioned to divert a portion of the gaseous product emitted from said burner rearwardly toward said space during the combustion of the gaseous product to provide said required heat.

RICHARD J. WALLER.

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

UNITED STATES PATENTS Number Name Date 1,102,984 Gleich July 7, 1914 1,331,985 Good Feb. 24, 1920 1,349,876 Doble Aug. 17, 1920 1,395,399 Doble Nov. 1, 1921 1,402,243 Metcalfe Jan. 3, 1922 1,574,545 Bear Feb. 23, 1926 1,594,731 Hopkins Aug. 3, 1926 1,676,501 Moors July 10, 1928 1,700,269 Loepsinger Jan. 29, 1929 1,700,592 Loepsinger Jan. 29, 1929 1,789,542 Caldwell Jan. 20, 1931 1,789,543 Caldwell Jan. 20, 1931 1,846,978 Parker et al Feb. 23, 1932 1,847,020 Parker et al. Feb. 23, 1932 1,860,958 Sallee May 31, 1932 1,876,025 Sallee Sept. 6, 1932 2,072,731 Crosb Mar. 2, 1937 2,121,271 SZabo June 21, 1938 2,157,265 Pothier et al. May 9, 1939 2,175,866 Arnold Oct. 10, 1939v 2,286,853 Holthouse June 16, 1942 2,374,203 Holthouse Apr. 24, 1945 FOREIGN PATENTS Number Country Date 724,027 France Jan. 23, 1932

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