US1702731A - Method of and apparatus for combustion otf - Google Patents

Description

Feb. 19, 1929.

H. A. HYMER METHOD OF AND APPARATUS FOR COMBUSTION OF FUELS Filed April 14, 1925 Patented Feb. 19, 1929.

UNITED STATES HERBERT'A. HYMER, OF DETROIT, MICHIGAN.

ma'rnon or AND APPARATUS non comausrrox our-Urine.

Application filed Aprfl 14, 1925. Serial No. 23,109.

My invention relates to combustion of fuels and more especially to the provision of a method of burnin such fuels as gas (such as the ordinaryil uminating gas), oil or powdered coal, such that the fuel will be burned with an extremely high degree of efficiencyand extremely high temperatures produced. The invention also relates to an apparatus or burner for carrying out my 1mproved process.

It is well known that the efficiency of prac. tically all burners heretofore made is relatively low and that the temperatures obtained from such burners are far below the theoretical flame temperature. By theoretical flame temperature I refer to the temperature attainable by the complete combustion of a completely combustible mixture without excess oxygen in a non-heat conducting chamber.

Of the'burner designed heretofore, by far the greater number are atmospheric burners, in that combustion takes place at substantially atmospheric pressure, the burners for the most part depending either upon induced air or air from the surrounding atmosphere for the support of combustion. While in some of these burners partial combustion takes place within a chamber or tube as distinguished from the majority wherein the flame is at the end of the burner mouth and surrounded by atmospheric air, in none of them does the combustion occur within a space within which the flow of the fuel and the combustion supporting medium, such as air, is so controlled that the combustion takes place under pressure, and therefore, in all such burners we have what may be termed a flash burner as distinguished from an explosive burner wherein the combustion takes place under pressure, or at least Within a space so 'confined that an explosion of the mixture is the res'ult rather than a mere burning or flashing there-of.

It is, of course, well recognized that a proper mixture of the fuel and the combustion supporting medium is necessary for efficient combustion and for the obtaining of high temperatures therefrom, and it is also recognized that if the-mixture is pre-heated prior to its combustion the. resulting temperature will be increased. 7

One object of my invention, therefore, is the provision of a method of burning a fuel so that the combustion takes place under pressure.

Another object of m invention is the provision of a method of urning a fuel whereby a proper mixture of fuel and a combustion supporting medium such as airwill be exploded under pressure within a confining space or chamber, whereby an exceedingly high temperature will be obtained.

A still further object of the invention is the provision of a burner whereby a proper mixture of afuel and a combustion supporting medium will be exploded within a combustion tube or chamber under pressure.

A still further object of my invention is the provision of a burner which will operate efiiciently in a back fire condition, so that the combustion takes place within a combust1on chamber in order that the mixture may be exploded while confined, and an' exceedingly high temperature is attained.

A still further object of my invention is the provision of a burner wherein a mixture of fuel and air is introduced into a combustion tube or chamber in a thoroughly mixed condition and there exploded,'so that com plete combustion takes place within the tube, and a flame temperature approaching that of theoretical flame temperature is attained.

Another object of my invention is the provision of a method of burning a fuel such that combustion takes place within a limited orconfined space at a very high rate of speed, phereby developing a very high temperaure.

To these and other ends the invention consists in the novel features and combination of parts to be hereinafter described and claimed. 1

In the accompanying drawings: 7

Fig. 1 is a sectional view of a burner embodying my invention and illustrating my improved process;

Fig. 2 is a similar view illustrating a modified form of my invention;

Fig. 3 is a sectional view of a further modification.

The burner which Ihave selected to illustrate in Fig. 1 of the drawings as one embodiment of my invention is like that shown in my co-pending application, Serial No. 633,978,filed April 23,1923, of which this application is a continuation in part, and comprises an air tube 1, receiving a supply of air from an air line 2, controlledby the valve 3. The fuel, which in the instance shown is in a. gaseous state, is introduced through thetube 6, controlled by the valve 4, from the gas line 5. I prefer to so construct the gas and air tubes that the former will be surrounded by the latter, so that as hereinafter explained, the supply of air will be introduced around the mouth of the gas orifice. To the. end of the gas supply tube 6 is connected a gas chamber 12, which may be enlarged at its intermediate portion to permit the gas to expand, and which preferably will have a constricted orifice 13 so that the velocity of the gas issuing therefrom will be somewhat increased. This also gives the chamber 12 a shape substantially elliptical in longitudinal cross section, and, as

.will be explained hereinafter, enables the wave action set up in the burner to be maintained or possibly augmented and built up by the action within this chamber.

To the air tube or conduit 1 is threadedly connected an air nozzle 7, the discharge end of which is tapered so as to conform closely to the wall of the gas chamber adjacent the discharge orifice 13. The air nozzle is preferably so shaped at this point that the air will be directed across the orifice of the gas nozzle in all directions in a substantially coneshaped stream, so that, the air supply being under pressure, the flow of gas will be increased by induction or drawn out. of the orifice 13 by the partial vacuum created by the stream of air passing across this orifice. It is noted that the space between the ends of the air and gas nozzles is annular in shape and tapers in a forwardly direction, becoming gradually smaller as the orifice end of the chamber 12 is approached, so that the air is conducted through this tapering annular space across the gas orifice and both gas and air supplied from the nozzle 7 and orifice 13,

I have only to rotate the nozzle 7 upon its threaded connection with the tube 1, so as to )roduce a relative longitudinal movement.

tween this nozzle and the chamber 12. If desired, a threaded connection 16 may be made between the chamber 12'and the gas tube 6, which threads will be disposed oppositely to those upon the nozzle 7 andtube 1, and radially extending pins 14 may be provided upon the chamber 12, which are received within recesses 15 upon the interior of the nozzle 7. It will be apparent that with this construction, when the nozzle 7 is moved to the right, as shown in the drawings, the chamber 12 will also be rotated and due to its oppositely threaded connection with the tube 6 will be moved to the left,

thereby effecting a very rapid change in the proportions of fuel and air supplied, with a relatively small amount of rotation of the tube 7. y

As the fuel and air issue from the nozzle 7 and orifice 13, they flow into 'a primary expansion or mixing chamber 8, which as shown, increases in diameter from its receiving end toward its discharge end where the mixture is discharged into a secondary mixing or expansion chamber 9. As shown in the drawings, this secondary expansion chamber is ellipsoidal in shape and is provided with a somewhat restricted orifice 10. The fuel and air are thoroughly mixed within these expansion chambers, and it will be un derstood that as long as a thorough mixing is obtained the exact shape of these chambers is not important in the broad aspects of the invention but may be considerably all aspects of the invention. The length of the tube may be Varied to suit conditions, but preferably the tube is sufficiently long so that a substantially complete combustion of the charge takes place therewithin so that few particles of the fuel are permitted to escape from the open end of the tube unburned, and also it is preferable to have the hot gases produced by combustion remain in the tube a sufficient length of time to heat the walls thereof, so that the contact between the walls of this tube and the wall of the chamber 9 will heat the latter and preheat the mixture. The mixture will also be preheated by the wall of the chamber 9, due to the heating of this wall directly from the heatof the combustion which takes place at the forward end of this chamber, as some of the explosions occur at this point as well as farther along in the combustion chamber 11.

In practice it has been found that the tube 11 gets cxceedinglyhot, and if this tube. is not constructed of certain materials of very high melting point and which do not tend to oxidize easily, the tube will quickly be destroyed due to the intense heat to which it is subjected. For instance, if this tube were made of cast iron or steel it would oxidize within a short time after the burner was lighted. I prefer to use for the construction of the tube, chrome nickel steel, or a metal composed only of chromium and nickel, but other materials may be used. It will be understood, of course, that as long as a metal is selected which will withstand the intense heat of combustion, the particular metal used may .be varied.

' The gas admitted to the burner through the pipe maybe and preferably isunder the low pressure which normally exists in the usual gas mains, that is, a .pressure of from a few ounces to a pound or more above atmospheric pressure. The pressure may, of course, be raised if desired, but this is not necessary for the efficient operation of the burner, al-

though gas pressures as high as fifteen pounds per square inch have been successively employed in my lu'n-ner, such pressures usually being accompanied by an air feed under a pressure substantiallyfour or five times as great. The air conducted to the burner through the conduit 1, isv preferably under pressure and this pressure may be comparatively high. a For instance, the burner has been found to operate elliciently with an air feed under a pressure of pounds per square inch, although an eflicient and satisfactory result is accomplished with considerably lower pressures. In fact, it is possible to employ my novel method in a burner in which the air is entrained at substantially atmospheric pressure so that a source of compressed air will, in such cases, not be absolutely essential to the operation of a burner embodyingmy invention. However, in the embodiment which I have selected to describe, it will be assumed that the burner is supplied with compressed air under a pressure of at least several pounds. This air under pressure is expelled from the air nozzle 7 in a stream which passes across the gas orifice 13 so that the gas will be inducted into the expansion and mixing chamber 8 by the partial vacuum created at the mouth of the orifice by the action of the stream of air. This induction will, of course, be aided by the gas flow due to the normal pressure existing charge passing therethrough, and when this,

charge lea-vesthe orifice 10 it will be seen that it will be permitted to expand and thereby vthe pressure of the charge is increased and the velocity reduced. I, therefore, have a premixed explosive or combustible charge of fuel and a combustion supporting medium which, in the instance described, is air, introduced into the combustion chamber. This charge is under pressure and While confined within the combustion tube or chamber con tains a suflicient amount of air to support combustion without havin to draw u n the atmosphere surrounding t e open e of the tube.

It is well recognized that the rate of combustion is a function of the temperature developed or attained by thecombustion. That is, when'fuel and oxygen combine at a more rapid rate a higher temperature or a greater intensity of heat will be developed. One method of increasing the combining speed of fuel and oxygen is by causing the combustion to take place under pressure or within a confined space. This principle is made use of in my burner wherein the pro-mixed charge of gas and air is introduced into a confined space or chamber and there burned so rapidly that it'ma be described as an explosivecombustion. hat is, the combining of the fuel and oxygen takes place substantially instantaneously and the result is that an explosion or multiplicity of explosions occur rather than a quiet or flash burning of the fuel.

This ressure is due to some extent to the fact that t 1e gas and air are caused to pass through a restricted orifice, which according to well known physical laws tends to increase the pressure within the charge after the orifice has been passed and the charge is ermitted to expand. This pressure is also ue to the initial pressures with which the gas and air are fed to the burner, the flow of the charge through the combustion tube being resisted by the pressure waves set up by the explosions within the tube so that at the point where the combustion or explosions take place the explosive mixture is confined and, therefore, a pressure is set up which results in a very high combining speed of the fuel and oxygen. I have, therefore, a pre-mixed and properly proportioned charge of gas and air introduced into the chamber 11 and there exploded or.

burned at a very high rate of combustion, the

charge being so proportioned that .substantially complete combustion may take place within this combustion chamber without the necessity of drawing upon the open end of the chamber for atmospheric air.

ltIoreover, the waves set up by the explosions occurring within the chamber cause a turbulence of the charge therein so that the charge instead of passing directly through the chamber as a pencil or solid stream, is caused to remain within the chamber for a suflicient length of time'to be substantially completely burnedbefore passing into the atmosphere. The products of combustion are thus caused to impinge against the wall of the chamber so that the latterbecomes very hot and by its contact with the chamber 9, preheats the charge and thus increases the attained temperature. g

This is of course in addition to thepreheating that occurs as a result of the combustion back and forth through the orifice 10 and it is therefore probable that some combustion occurs within the mouth of this chamber at least a part of the time.

It will be noted from the above description tlnt't my burner burns in a back-tire condition. That is, the-combustion takes place near the mouth of the orifice 10 instead of at the mouth of the tube 11. The zone of combustion extends forwardly from this point, its extent depending upon the conditions under which the burner is used. \Vhen the charge is conducted into the chamber under a relatively high pressure, the zone of combustion may extend practically throughout the length of the chamber, depending, of course, to some extent upon the length of the chamber. It is usually the case when a burner back-tires, as for example the common .form of Bunsen burner, that very inefficient action results and steps are taken to prevent such action. My burner, however, is COIlSlZl'llCtQtl to burn normally and most eiliciently in this back-tire condition, as it is due to this principle that the substantially instantaneous combustion of the pro-mixed charge takes place and thus an extremely high temperature is developed.

In starting the burner, relatively small amounts of both gas and air are fed thereto. The burner is then lighted and a cone of flan-1e appears at the open mouth of the combustion tube 11. The air supply is then increased and the flame finally jumps back to the mouth of the orifice 10 so that the back-fire condition is established. The burner now operates upon the explosive principle and burns with a very loud noise. The supply of both gas and air may then be increased and if the proper proportions of the fuel and air are maintained, the amount of the charge may be greatly increased without choking, or without surpassingthe consumptive capacity of the burner, and withoutblowing the flame out of the combustion tube, although the velocity of the charge in aforward direction, under the high pressures used in some instances, may be greater than the velocity of flame propagation rearwardly. This forward velocity of the charge is, however, resisted by the pressure waves of the explosions so that it may be said that a balance is reached where the net velocity of the gases passing through the combustion chamber is substantially equal to the velocity of flame propagation. so that combustion takes place in the vicinity of the mouth of the orifice 10. The combustion, therefore, takes place mainly'within the combustion chamber or tube 11, and takes place substantially the instant that the charge only induces the gas from the orifice but acts as a shield against the pressure existing in the combustion tube.

It is noted that in the form of my. invention shown in Fig. 1 of the drawings, the chambers 12 and 9 are ellipsoidal in shape or substantially elliptical in longitudinal cross section. According, to well known physical principles, a pressure wave or a' wave of comlensation emanating from one of the foci will be concentrated at the other focus and returned from that point and again concentrated at the first focus, where it may, in conformity to the principles of resonance, amplitythe following waves emanating from the first focus, so that pressure waves of considerable amplitude or intensity may be set up. This principle is of importance in this form of my invention, I believe, for when the explosions take place adjacent the orifice 10, some of these explosions occur within the forward portion. of the cl'iamber 9, or at least set up oscillatory Waves within this chamber. These waves are reflected from the walls of the chamber and returned to the point of emanation where they serve to amplify the follo'w ing explosion waves, and thus build up the pressure under which the explosions occur. These oscillations, in all probability, pass into the tube 11 through the orifice 10, so that they amplify the pressure under which the combustion takes place in the combustion tube. Likewise, this oscillating back and forth of the layer of ignition exerts an influence upon the stream of fuel within the chamber 12 through the chamber 8, and, therefore, the effect of the chambers 12 and 8 is to maintain the oscillatory explosive action which occurs adjacent the orifice 10 and perhaps to amplify this action. That is, the pressure waves set up within the chamber 9 by the explosions, pass by propagation through the chzunber 8 into the chamber 12 so that throughout the chambers 12, 8 and 9 an oscillatory pressure wave action is set up, which according to the principles of resonance amplifies the explosive waves and results in an increased density of the mixture at the points where the explosions occur, causing the development of a higher temperature owing to the more intimate contact between the molecules when combustion occurs. This wave action in chambers 8 and 5) also results in the production of a thorough mixture of the fuel and air within these chambers.

The shape of the tube 11 will affect the shape of the flame and this shape may he cried to provide the kind of flame desired when the burner is used for various purposes. For instance, a tube tapering inwardly toward its outer end will provide a concentrated flame of great intensity, while a tube flaring or tapering outwardly toward this end will result in a large flame of less concentration. It will be, of course, understood that the mouth of thetube'may be so shaped as to cause a flame of crescent, diamond, or

star sha es which may be desired in certain kinds 0 work. As previously stated, the length of this tube may be varied but I have found that within certain limits, increasing the length of the'combustion tube increases the noise made by the burner and apparently the temperature of the flame. The tube should be suificiently long so that substantially complete combustion of the fuel takes place therewithin.

Contrary to what might be expected of a burner when operating 1n a backfire condition, the flame within the combustion tube of my burner is of a bluish-green color in contrast to the usual yellow back-fire flame, thus indicating that substantially complete combustion takes place within the tube.

In Fig. 2 of the drawings, I have shown a burner similar: to that shown in Fig. 1, but

differing therefrom in certain details of construction. The gas conduit is represented at 5, the air conduit at 1", and the air nozzle at 7", having a threaded connection at 7 a with the conduit 1 so that the proportions of gas and air flowing through the burner may be regulated. The chambers 8, 9 and 12 are of substantially the same form as the corresponding elements shown in Fig. 1. There is, however, in this construction no adjustable connection between the gas conduit 5 and the chamber 12. The combustion chamber 11 is slightly flared, as shown at 20, so as to provide for a less concentrated flame than would be obtained if this chamber were of smaller diameter. The openings 20 are provided in order to afford a convenient method of lighting the burner when it is started. The action whichtakes place in this burner is, however, substantially the same as that which occurs in the form previously described.

In Fig. 3, I have shown a further embodiment of my invention, which is similar to that shown in Fig. 2, except that the mixing chambers 8 and 9 have been combined into a single chamber 9 which is enlarged or flared toward its forward end so as to be substantially semi-ellipsoidal in shape. The gas and air issuing from the nozzle 7 d and the orifice 13 will be mixed in the chamber 9, and will burn or explode, as previously described, beginning at a point adjacent the mouth of this chamber where the charge issues into the combustion chamber 11. The wave action previously described, is set up in the chambers 12 and 9, and this, together with'the initial pressures with which the gas and air are supplied to the burner, willcause the charge to be burned or exploded under pressure while confined by the walls of the combust-ion chamber 11. in all forms of my invention, the charge is burned' within a combustion chamber and It will be'noted that that prior to the time this chamber is reached it is passed throughone or more chambers, which will be conducive to maintaining or augmenting the wave action as set u by the explosions. In other words, the c ambers are so arranged as to be in a state of-resonance, so that the explosion waves will be reflected from the chamber walls, and thus cause an increase in the pressure under which the charge is exploded.

' It has been determined that my burner is of greater. efliciency than those heretofore used, and its use, therefore, results in a substantial saving in the fuel employed in a given operation.

It will be understood, that although I have described the operation of my burner particularly with reference to the use therein of ordinary illuminating gas as fuel, that other fuels may be used as well. For instance, I may use oil or powdered coal, and while certain modifications may be necessary in the mixing and vaporizing of the charge of fuel and air, the underlying principle will be the same. That is to say, the fuel will be conducted into and burned within a confined space or chamber so that combustion takes place within a restricted space under pressure, thus increasing the temperature devel- While I have shown and described some preferred embodiments of my invention and a preferred method of carrying out my improved process, it will be understood that the details of both apparatus and process may be greatly varied without departing from the spirit of my invention or from the scope of the appended claims.

What I claim is:

1. The method of obtaining a high temperature from the combustion of a fuel, which comprises introducing a charge of the fuel and air into a mixing chamber, mixing the charge therein and passing it into a combustion chamber having an open mouth, igniting the charge so as to initially cause a flame at the mouth of the chamber, increasing the supply of air to cause the back-fire of the flame to a point adjacent that at which the mixture is introduced, and then increasing the supply of fuel and air to bring about a vigorous back-fire combustion of the fuel within the end of the chamber remote from the mouth.

2. The method of burning a vaporized fuel and air to obtain a high temperature therefrom, which comprises introducing into a mixing chamber a charge of the fuel and air in explosive proportions, mixing the charge therein and passing it into one end of an elongated combustion tube having an open mouth at the other end, and bringing about combustion of the fuel within the combustion tube adjacent the point of admission of the gas and air so as to build up a pressure within the tube to resist the oncoming pressure of the charge and insuring the combustion taking place within the tube.

The method of burning a vaporized fuel to obtain a high temperature therefrom, which comprises introducing a charge of the fuel and air in proper explosive proportions and under pressure into a mixing chamber, mixing the charge therein, passing the charge directly into one end of an elongated combustion tube having an open mouth at the other end, and bringing about combustion of the fuel within the combustion tube adjacent the oint of admission of the gas and airso as to mild up a pressure within the tube to resist the on-coming pressure of the charge to prevent the zone of combustion moving forwardly to the end of the combustion tube.

4:. A method of burning a fuel to obtain a high temperature therefrom, which comprises forcing a mixture of the fuel and air under pressure into one end of, and in line with the mouth of, a tubular combustion chamber having an open mouth, and exploding said mixture adjacent its point of admission whereby pressure is built up in the chamber to resist the movement of the oncoming mixture and prevent the zone of combustion passing out the end of the chamber.

5. The method of obtaining a high temperature from a mixture of fuel and air, which comprises introducing under pressure through a single orifice a mixture of the fuel and air into one end of, and in line with the mouth of, an elongated combustion chamber having an open mouth, and exploding the mixture, while maintaining the explosive zone within the chamber so that substantially complete combustion takes place therein.

6. The method of burning a fuel to obtain a high temperature from the combustion thereof, which comprises introducing into a combustion tube open at one end a pro-heated and pro-mixed charge of fuel and air in a di- F rection in line with said. opening, and bring ing about substantially instantaneous combust-ion of the fuel within the tube.

7. The method of burning a fuel to obtain a high temperature therefrom, which comprises introducing the fuel and air into a mixing chamber, causing a thorough mixture of the two Within said chamber, conducting the mixed charge into a combustion chamber 0 n at one end, and there burning said c arge at an extremely high rate of speed to develop a high temperature.

8. The method of burning a fuel to obtain a high temperature therefrom, which comprises introducing the fuel and air into a mixing chamber having a restricted outlet, causing a thorough mixture of the two within said chamber, conducting the mixed charge through said outlet into acombustion chamber open at one end, and there exploding said charge while confined within the combustion mixed within said chamber, conducting said charge into a combustion chamber and there exploding the same to cause substantially complete combustion of the fuel within said chamber.

10. The method of burning a gaseous fuel 7 to obtain a high temperature from the combustion thereof, which comprises delivering to a mixing chamber having curved walls a stream of the fuel surrounded by a stream of air, the latter being directed across the path of the fuel whereby the charge is thoroughly mixed within said chamber, pre-heating said charge, conducting said charge into a com bustion chamber and there exploding the same to cause substantially complete combustion of the fuel Within said chamber.

11. A fuel burner comprising an elongated combustion chamber open at one end, means for introducing into said chamber at a point remote from the end a ire-mixed charge of fuel and air, means or controlling said charge to cause a back-fire of the burner whereby the charge is caused to burn adjacent the point at which it is introduced into the chamber, and-causing substantially complete combustion to take place while the charge is within the chamber to develop a high temperature, and means for pre-heating the charge from the hot combustion tube.

12. A fuel burner comprising a combustion chamber open at one end, means for introducing into said chamber in a direction in line with the open end, a pre-mixed charge of fuel and air, and means for causing substantially instantaneous combustion of the fuel within the chamber.

13. A fuel burner comprising a combustion chamber open at one end, means for introducing into said chamber a pro-mixed charge of fuel and air, and means for controlling said charge so as to bring about the combustion of the fuel within the chamber under pressure including an ellipsoidal mixing chamber through which the charge passes to the combustion chamber.-

14. A fuel burner comprising an elongated combustion chamber open at one end, means for introducing into said chamber in a direction in line with said open end a continuous stream of fuel and air in pre-mixed condition, and means for causing the continuous combustion of the fuel within the chamber at a high rate of speed.

15. A fuel burner comprising a combustion chamber open-"at one end, means for -intro ducing into said chamber a pre-mixed charge of explosive proportions of fuel and. air and means for controlling the passage of the ;.ch arge through the, burner to cause the combustion of the fuel supported by the air of the charge adjacentthe point at whichthe charge is introduced into the chamber includ ing a mixing-chamber through whichthe charge passes to the combustion chamber. a

16. A fuel burner comprisingacombustion chamber open. at one end, means for introducinginto said chamber a pre mixed charge of proper proportions of fuel and air, and

;means for controlling the passage of the chargethrough the burner to cause the com- .ducing into said chamber apre-mixed charge of fuel and air, and means for controlling said charge to cause the combustion of the fuel to take place adjacent the point of its entrance into the combustion chamber in a back-fire condition including a mixing chamber through which the charge passes to the V reflected from'the walls of the preceding combustion chamber.

18. A fuel burner comprising a combustion combustion takes place under pressure,

chamber open at one end, means for introducing into said chamber at a point remote from, and in a direction in line with said end, a pre-mixed charge of fueland air, means for pro-heating said charge, and means for causing the combustion of said pre-heated charge to take place adjacent its point of entrance I into the chamber under pressure.

19. A fuel burner comprising a combustion chamber open at oneend, means for introducing into said chamber at a point remote from, and ina direction in line with said end, a pre-mixed char e of fuel and air, means for causing the com ustion of said pre-mixed charge to. take place within the chamber, and

means to pre-heat the charge from the heat of combustion in the burner.

20. A fuel burner comprising a combustion chamber open at one nd, means to introduce ,g'nto said chamber at a point remote from, and in a direction inline with said end, a charge of fuel and air, and means to cause combustion of said charge under pressure in said chamber at a point adjacent its entrance in a back-fire'condition whereby the wall of said chamber is heated and the charge preheated as it. enters the chamber.

21. The methodof burning a v a high degree of heat therefrom, which comprises introducing a pre-mixed charge of fuel and air'into a combustion chamber, exploding saidcharge within the chamber and so fuel to obtain controlling the charge that the explosive waves set up are reflected and amplified to cause the combustion to take place under pressure.

22. The method of burning a fuel, which comprises pre-m xing the fuel and air in a mixing chamber, introducing the charge from this chamber into a combustion chamber, and

there causing combustion to take place adja- V cent the oint of entrance, and so controll1 ng the c arge in its assage to,;the combustion chamber that exp osions will theretake place underpressure and the explosive waves will be reflected, and the pressure under which combustion takes place will be built up.

23. The method of burning a fuel in a colnbustion chamber open at one end, which comprises passing the fuel, into said chamber through a preceding chamber and causing it to explode in the combustion chamber, and

so controlling the passage of the fuel through said v preceding chamber that the explosive waves set up will be reflected by the walls thereof and thereby build up the pressure under which the combustion takes place. i

24. The method ofburning a fuel ina combustion chamber in back-fire condition, which comprises passing the charge of fuel into said chamber through one or more chambers having curved walls, whereby the explosive waves v set up in the combustion chamber are chamber and amplified thereby so that the preceding chamber and amplifiedthereby and cause an increase in the pressure under which the explosions take place.

. 26. The methodof burning a fuel in a combustion chamber under pressure, which comprises introducing a charge of fuel and air into said chamber under pressure through a preceding chamber of ellipsoidal shape, and causing the combustion of the charge to take place adjacent its entrance into the combustion chamberwhereby the explosive waves set up will be reflected from the walls of the el-. lipsoidal chamber, and combustion will take place under increased pressure.

27. The method of burning a fuel which comprises causing a charge of said fuel and air to explode in a combustion chamber in back-fire condition, introducing the fuel into the chamber througha preceding chamber of ellipsoidal shape, whereby the explosive waves will be reflected from the walls of said chamber in resonance with subsequent explosive waves and thereby build up the pressure under which combustion takes place.

28. The method of burning a fuel which comprises premixing a charge of fuel and air in a chamber having curved walls, introducing said charge under pressure into a combustion chamber controlling said charge so that combustion takes place within the latter chamber under pressure with the burner in a back-tire condition whereby the explosive waves set up are reflected froin'the curved walls of the first chamber and the pressure is thereby amplified.

29. The method of burning a fuel which comprises pre-mixing and pro-heating a charge of fuel and air in a chamber having curved walls, introducing said charge under pressure into a combustion chamber, controlling saidcharge so that combustion takes place within the latter chamber under pressure with the burner in a back-fire condition whereby the explosive waves set up are reflected from the curved walls of the first chamber and the pressure isthereby amplified.

30. The method of burning a fuel, which comprises introducing a stream of said fuel into. a mix ng chamber, introducmg a1r into said chambemnnder pressure in a direction across the fiiel stream from all sides thereof, in cone-shaped fashion so as to cause a thorough mixing of the fuel and air in said chamber, passing the mixed charge into a combustion chamber and there causing said charge to burn adjacent its point of entrance into the combustion chamber.

31. A fuel burner comprising a mixing chamber having curved walls and restricted in cross-sectional area adjacent one end, means for introducing a stream of fuel into said chamber, means for introducing a stream of air under pressure into said chamber around the fuel stream whereby a thorough mixture of the fuel and air is obtained, a combustion chamber, means for passing the mixed charge into the combustion chamber and causing the combustion to take place therein under pressure.

32. A fuel burner comprising a mixing chamber having curved walls, means for introducing a-stream of fuel into said chamber, means for introducing a stream of air under pressure into said chamber around the fuel stream and directed across the latter from all sides, whereby a thorough mixtureof the fuel and air is obtained, a combustion chamber, means for passing the mixed charge without addition of air thereto into the combustion chamber and causing the combustion to take place therein under pressure.

33. A fuel burner comprising a mixing chamber substantially ellipsoidal in shape, means for introducing a stream of fuel into said chamber, means for introducing a stream of air under pressure into said chamber around the fuel stream whereby a thorough mixture of the ful and air is obtained, a

combustion chamber, means for passing the mixed charge into the combustion chamber and causing the combustion to take place therein under pressure.

34. A fuel burner comprising an elongated combustion chamber, a preceding chamber communicating therewit-l'i and having curved walls, means for introducing into said preceding chamber an unignited supply of fuel and a supply of air under ressure, means for causing the combustion o said fuel in the combustion chamber at a high rate of speed, and means for re-heating the mixed charge prior to its com ustion.

35. A combined mixing nozzle and combustion chamber consisting of a pair of telescoping members, on constituting an air c'onduit and the other a conduit, said air conduit connecting to an e xp nsion chamber at the discharge end of the as conduit, and a restricted nozzle substantial elliptical in longitudinal cross section be end the discharge end of the gas conduit an extending into the combustion chamber.

36. A combined mixing nozzle and combustion chamber consisting of a pair of telescoping members, one constituting an air conduit and the other a gas conduit, said air conduit connecting to an expansion chamber at the discharge end of thegas conduit, and a restricted nozzle beyond the discharge end of the gas conduit and extending into the combustion chamber, said conduits being adjustable relative to each other to control the relative flow of gas and air.

37. A combined mixing nozzle and combustion chamber consisting of a pair of telescoping members, one constituting an air conduit and the other a gas conduit, said air conduit connecting to a substantially ellipsoidal expansion chamber at the discharge end of the gas conduit, said ellipsoidal chamber having a restricted nozzle beyond the discharge end of the gas conduit and extending into the combustion chamber, said expansion chamher being formed of a smaller portion adjacent the gas nozzle and a larger portion adjacent the restricted discharge opening of theair conduit.

38. A combined mixing nozzle and combustion chamber consisting of a pair of telescoping members, one constituting an air conduit and the other a gas conduit, said air conduit connecting to an expansion chamber at the discharge end of the gas conduit, and a restricted nozzle beyond the discharge end of the gas conduit and extending into the combustion chamber, said gas conduit being substantially elliptical in cross section adJacent its discharge end to reduce the friction therein and to increase the discharge.

' 39. A gas burner comprising a tubular combustion chamber, a substantially ellipsoidal expansion chamber connected thereto and discharging into the combustion chamber through a restricted nozzle, a substantially ellipsoidal gas nozzle aligned with the mixing chamber, and an air nozzle surrounding the gas nozzle and integral with the mixing chamber, said air and gas nozzle being formed to permit longitudinal adjustment between the gas nozzle and the mixing chamber.

40. The method of burning a fuel to obtain a high temperature therefrom, which comprises introducing .into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, passing the mixed charge in a longitudinal direction into one end of an elongated combustion chamber open at the other end, con fining the charge laterally in the chamber and bringing about combustion of the fuel thcrewithin under pressure.

41. The method of burning a fuel to obtain a high temperature therefrom, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, passing the mixed charge in a longitudinal direction into one end of an elongated combustion chamber open at the other end, confining the charge laterally in the chamber, and bringing about substantially complete combustion of the fuel prior to the emission of the charge from the chamber.

42. The method of obtaining a high temperature from the combustion of the fuel, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, mixing the fuel and combustion supporting medium therein, and passing the mixed charge directly into a combustion chamber having an open mouth, and bringing about combustion of the fuel within the chamber under pressure.

43. The method of obtaining a high temperature from the combustion of the fuel, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, mixing the fuel and combustion supporting medium therein. and passing the mixed charge directly into a combustion chamber having an open mouth, bringing about sub stantially complete combustion of the fuel under pressure while the charge is within the chamber.

44. The method of obtaining a high temperature from the combustion of the fuel, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, mixing the fuel and combustion supporting medium therein, and passing the mixed charge directly into a combustion chamber having an open mouth and then exploding lsjaid mixture under pressure within the cham- 45. The method of obtaining a hightemperature from the combustion of the fuel, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, mixing the fuel and combustion supportin medium therein, and passing the mixed cl'iarge directly into a combustion chamber having an open mouth, and causing the combustion of the fuel supported by the combustion medium of the charge adjacent the point at which the charge is introduced into the chamber.

46. The method of obtaining a high temperature from the combustion of the fuel, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, mixing the fuel and combustion supporting medium therein, and passing the mixed charge directly into a combustion chamber having an open mouth, and causing the combustion of the fuel supported by the combustion medium of the charge adjacent the point at which the charge is introduced into the chamber, and confining the charge laterally during the combustion of the fuel.

47 The method of burning a fuel to obtain a high temperature therefrom, which comprises introducing into a mixing chamber a supply of fuel and a combustion supporting medium in explosive proportions, passing the mixed charge in a longitudinal direction into one end of an elongated combustion chamber open at the other end, confining the charge laterally in the chamber. and bringing about a backfire combustion of the fuel Within the chamber.

48. A fuel burner, comprising a combustion chamber open at one end and having means to receive a charge of fuel and air adjacent the other end, said chamber being elongated in a direction between said ends, means for delivering at the receiving end of said chamber an explosive mixture of fuel and air, and bringing about the explosion of the fuel while confined within the chamber.

49. A fuel burner, comprising a combustion chamber open at one end and having means to receive a charge of fuel and air adjacent the other end, said chamber being elongated in a direction between said ends, means for delivering at the receiving end of said chamber an explosive mixture of fuel and air, and bringing about substantially complete combustion of said fuel while pass- .ing through the chamber.

50. A fuel burner, comprising a combustion chamber open at one end, and having means to receive a charge of fuel and air ad jacent the other end, said chamber being elongated in a direction between said ends, means for delivering at the receiving end of said chamber an explosive mixture of fuel and air, and bringing about substantially complete combustion of said fuel under pressure while passing through said chamber.

- 51. A fuel burner, comprising a combustion chamber open at one end and having means to receive a charge adjacent the other end, said chamber being elongated in a direction between said ends, means for introducing adjacent thereceiving end of the chamber an unignited premixed charge of fuel and air, and for controlling said charge to cause a back-fire of the charge Within the burner, whereby the charge is caused to burn adjacent the point at which it is introduced into the chamber, and substantially complete combustion takes place prior to the emission of the charge from the chamber to develop a high temperature. 1

52. A fuel tion chamber, a mixing 0 amber communieating with the combustion chamber, means fordeliverin a charge of fuel and air to the mixing cham er, passing it therefrom to the burner, com rising a combuscombustion chamber, and causing the combos tion of this charge to take place adjacent its point of entrance into the combustion chamber under pressure, and said mixing chamber having curved walls to-cause the explosive waves set up to be amplified by reflection from the walls thereof. i

53. A fuel burner, comprisin a combustion chamber, a mixin chamber having curved walls communicatmg with the combustion chamber, and means to deliver a charge of fuel and air to the mixing chamber, cause it to pass therefrom to the combustion chamber, and cause an explosion of said charge to take place under pressure within the combustion chamber, the explosive waves set up thereby being reflected from the curved walls of the mixing chamber soas to increase the pressure under which combustion occurs.

In witness whereof, I have hereunto set my hand this 8th day of April, 1925.

HERBERT A.

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