US2628475A - Jet combustion device embodying pretreatment of fuel before combustion - Google Patents

Description

Feb. 17, 1953 D. P. HEATH JET COMBUSTION DEVICE EMBODYING PRETREATMENT 0F FUEL BEFORE COMBUSTION Filed June 26, 1946 2 SHEETS-SHEET 1 INVENTOR RNEY M073/ any ZZ/w40 7? H54 r/q/ Feb. 17, 1953 D, P HEATH 2,628,475

JET COMBUSTION DEVICE EMBODYING PRETREATMENT OF FUEL BEFORE COMBUSTION Filed June 25, 1946 2 SHEETSwSI-IEET 2 lNvENToR 7-2 2; ATTO/R@ Patented Feb. 17, 1953 J ET. COMBUSTION DEVICE; EMBODYING PRETREATMENT OF. FUEL: BEFOREA COMIBUSTION4 Donald P; vHeath;x Delaware Township, CamdenA County,y N. J., assignor to` Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application June26, 1946 Serial No. 679,434l

6 Claims.

This invention has to do with improvements.

in jet combustion devices..

Jet combustion devices have received prominence recently inA connection with jet-propulsion. In essence, jet combustion as now commonly used, and as used herein, refers to` a method of combustion wherein fuel is. continuously introduced intoY and continuously burned inaconned space. for the purpose of deriving power directly from the hot products. of combustion.

The simplest` jet.- propulsion devicev is a tube, closed at one end, in which a fuel is burned. The

gases of combustion emitted from the open end` of the-tube give rise to a reaction effect driving the tube in a direction opposite' to that of the emission of gases. The most complicated jet propulsion mechanisms yet proposed consist of a plurality of somewhat similar combustion tubes, plus. a compressor to supplyl air to the combus-` tion tubes, plus a gas turbine arranged to take enough energy from the efuent combustion gases.

to drive the compressor, plus a jet tube or reaction tube through Which the gases are. exhausted to provide driving power; Similarl combustion tubes. are utilized in gas. turbines, which usually differ from the jet. `propulsion engine: above described only in that provisions are made to extract most of theenergy fronrthe: gases;l in the turbine rathery than by' reaction from thev exhaust.. In some; cases, of jet propulsion, the compressor and its driving turbine aredispense'd with, combustion air being furnished by the ram effect, i. e., air in desired quantities flows into the combustion tube solely by virtue of the movement of the jet propulsion mechanism with respect tov thesurrounding air.

In all such combustions, whether forA jet propulsion or for a gas turbine, moving' or stationary, the optimum performance is that which will attain the highest stable rate' of heat' release in the combustion.

Selecting as typical an airplane-jet propulsion mechanism of the coupled compressor-burnerturbine-reactor type, study shows that various design considerations reduce the many variables whichv might affect the rateV of heat release to only a few. Air ratewithin theY combustion tube, preselected by design to always give an excess, becomes a function of ambient air pressure once the compressor is selected, and is relativelyfixecll for any altitude of operation, air'speed; and ambient temperature. Turbulence within` the combustion chamber/is held at a high level, but, since it is achieved only at the expensev of" theoverall 2. efficiency-of the mechanism, vmay be regarded as non-variant'. Substantially the sole variable which remains is the fuel. It is not only imperative that the fuelhave high flame stability, i. e., ability to burn at a high rate without blowout, but also that the fuel have a high heat release, as measured by taking the temperature difference across the combustion tube at a given air rate: With fuels of the same general order of flame i stability', the more useful fuel is the one which will deliver the greater heat release at a givent air rate,

This invention is based upon the` discovery that certain changes in the manner of handling the fuel immediatelyv prior to and at the point of combustion give rise to increases in name stability and rate of heatrel'ease of a fuel. These changes may readily be incorporated in ther combustion mechanism, and when so incorporated effect significant improvements in the use of any fuel appropriateA to the burner in which they are incorporated.

It is an object ofv this invention to provide a jet combustion mechanism capable of effecting av thermal pretreatment of the fuel' prior' to combustion. This and other objects which are in part obvious andwhich in part may be referred to hereinafter may be understood byreference to the drawings of this. specification.

In the drawings, Figure l shows in` section on line l-I of Figure 2, and Figure 2 shows in end view, .ay combustion tube so modified as to embody ythe teachings of my invention.

The other figures of the drawing namely Figures, 3 and 4, in which Figure 3 is a longitudinal section taken along line 3, 3 of Figure 45 and Figure 4 a cross section along linel 4, 4 of Figure, 3; Figures 5 and 6, in which. Figure 54 is. a

longitudinalv section taken at line. 5, 5 of Figure 6 and Figure 6 is a cross sectiony taken. aty line 6, 6 of FigureV 5; and Figures. 7 and. 8 in which Figure. 7 is alongitudinal section. taken at line 1,. 1 of Figure 8. andi Figure 8 is a. cross. section taken at line 8, 8 of Figure. 7 show other forms. of modif-ledcombustion tubes. The inventiorrwill be explained particularly in connection with Figures 1 and 2.

In Figure 1 of the drawing, 3 isv the outer casing or shell of the combustion tube, and 4 is the combustion tube itself, the casing 3 and tube 4 being so arranged, coaxially, as to providev .an annular passage fforthe flow of combustion air which air enters under pressure, either due 'to af compressor orto ramy eifect',` at the lef-t hand end of the burner as shown. Combustion tube 4 is provided with a number of holes 6 both at its left hand end and spaced along its length, whereby air from passage 5 may enter the interior of combustion tube 4. For the purpose of clarity only a few such holes 6 are shown. In practice, they will be spaced along tube il somewhat in keeping with the demands for air in its interior, and will be most plentiful in number at the closed end (left hand in the drawing), of the combustion tube 4. This manner of introducing air to a combustion tube and of controlling its rate and point of entry thereto is common in the art.

In the ordinary combustion tube, fuel is delivered at the center of the tube by a singlejet pipe or nozzle extending thereinto.

In contrast thereto I have provided a central tube l in which fuel is introduced to the burner tube 4 and in which the fuel is preconditioned or preheated to give it enhanced llame stability and heat release capability. Since-the fuel upon release must be reversed in direction, I have also provided a turning baille 8 of cupped shape'fin which, if desired, there may be placed a reentrant conical ilow splitter 9. Tube 'l is, of course, open at itsy forward end, at i6, and is closed at its rear end by plate H. Fuel is fed to tube l through one or more fuel pipes l2. (Four such pipes with attendant parts are shown in the drawing-see Figure 2.) nates in a nozzle I3 mounted in a casing i4. Within casing i4 there is a Venturi tube l5, into the throat of which nozzle i3 extends. Air from passage 5 is permitted to enter the space within casing l through ports i6 and is entrained with fuel in the injector formed by venturi i5 and nozzle I3, the resulting mixture being passed into tube I through an opening il'. poses, in fact for most, the relative amounts of air and fuel thus mixed can be predetermined by proportioning of the nozzle i3 and throat l5. However, should flexibility in this proportioning be desired or desirable, adjustability can be achieved quite simply by providing a sleeve mounting for fuel tube I2 and an external adjustment of any convenient kind, such as a threaded mount, whereby nozzle i3 may be advanced and retracted with respect to throat l5.

In any event, the amount of air admixed with the fuel and passing through tube l is insufficient for combustion of the fuel supplied thereto. However, this fuel-air mixture, too rich for combustion, is exposed to a high degree of heat by radiation and convection from the walls of tube 1, which are surrounded by the combustion space. Under such heat and in the presence of limited amounts of oxygen, I have found that apreconditioning of some sort takes places in the fuel which permits of more eiiicient combustion and higher rates of fuel burning, i. e., higher heat release for a given air rate. In other words, if one operates the burner here disclosed in parallel with a burner of ordinary type, in which fuel is merely introduced into the left hand end of combustion tube 4 through a simple nozzle, both burners being operated with air at the same pressure and temperature fed to each at the same rate, feeding the same fuel to each burner, and gradually increasing the rate of fuel supply until blowout is experienced, the novel burner here disclosed will be found to be capable o f burning more fuel than the conventional burner.

I do not Wish to advance any explanatory theory in such manner as to be bound thereby, but it is my present belief that a combination of incipient Each fuel pipe l2 termi- 2 For man'y Dur-l d oxidation and high temperature cracking of the fuel is responsible.

The temperatures attained in this novel burner are of somewhat the following order. Air at inlets i6, about 500 F. Fuel-air mixture at ports Il', 50o-600 F. Temperature of gases in combustion space just outside wall of tube l, around e000" F. Temperature of preconditioning mixture inside tube 1, about 1500 F.

Whatever the reason be, I have found that with the novel burner substantially more fuel per pound of air can be burned than with the ccnventional type of burner, and that a stable flame can be maintained over a wider range of pres sure and air flow conditions.

Turning now to Figure 3 and its companion Figure 4, I show a different construction. In this figure jacket tube 3 and combustion tube Il defining annular air space 5, from which air can pass into the combustion space through holes t, are essentially the same as before. The pretreatment mixture is attained by disposing a number of tubes i8 (four only are shown, althcugh there may be more or less) around the inside of the jacket tube 3 in such manner that air will enter their left hand end. Fuel is introduced into these tubes I8 through fuel jets l 9 and, with er without the assistance of a venturi the fuel and an amount of air insufhcient to support combustion are mixed. This mixture flows along tube i8 and is returned through that portion of the tube designated lying inside the combustion chamber wherein the pretreatment mixture is subiected to the high temperature of combustion, finally being discharged inside the closed left hand end of the combustion tube 4.

In Figures 5, 6, 7, and 8 a slightly different application of the same principle is shown. It will be remembered that the products of combustion contain a very considerable amount of excess air and are at a quite high temperature,vv

In Figure '7, another modification along the line of this latter idea is shown. Here again Vjacket.

tube 3, combustion tube t, air E and the communication holes 6 vare found. In this case a plurality of tubes 25 are arranged around the external periphery of jacket tube 3 and provided each with an end 2 wherein-the air rich combustion gases may enter urged both by their own velocity and also by the aspirating action of fuel introduced through jet 2li. Pretreatment of the fuel mixture then takes place in the leftward extension of tube 25 under the influence of the temperature of the gases aspirated at lil and the heat thrown into tube 25 chiefly by radiation from the adjacent combustion, after which the pretreated fuel mixture is discharged into the left hand end of the combustion chamber by pipe 26.

It will be obvious thatrnany other modifications embodying the general idea set forth herein and even the specific ideas set forth in the figures -may be made and all such are considered tobe within the scope of the invention subject only to such limitations as are found in the following claims.

I claim:

1. A jet combustion burner comprising an air tube, a combustion tube, and a pretreatment tube coaxially assembled, to provide an annular air passage around the combustion tube and an annular combustion space around the pretreatment tube, a closed end on the combustion tube toward the inlet end of the air tube, orifice means to introduce air from the annular air passage into the combustion tube at spaced points near its closed end and along its length, the pretreatment tube being shorter than the combustion tube, terminating in an open end near the closed end of the combustion tube, the opposite end of the pretreatment tube being closed, means to introduce fuel into the pretreatment tube near its closed end, and means to admix a limited amount of air with said fuel in said pretreatment tube.

2. A jet combustion burner comprising an air tube, a combustion tube, and a pretreatment tube assembled with the combustion tube inside the air tube to provide a passage for air around the combustion tube, and with the pretreatment tube inside the combustion tube a closed end on the combustion tube toward the inlet end of the air tube, orifice means to introduce air from the near the closed end of the combustion tube, the

opposite end of the pretreatment tube being closed, means to introduce fuel into the pretreatment tube near its closed end, and means to admix a limited amount of air with said fuel in said pretreatment tube.

3. A jet combustion burner comprising an air tube, a combustion tube, and a pretreatment tube coaxially assembled, to provide an annular air passage around the combustion tube and an annular combustion space around the pretreatment tube, a closed end on the combustion tube toward the inlet end of the air tube, orifice means to introduce air from the annular air passage into the combustion tube at spaced points near its closed end and along its length, the pretreatment tube being shorter than the combustion tube, terminating in an open end near the closed end of the combustion tube, the opposite end of the pretreatment tube being closed, means to introduce fuel into the pretreatment tube near its closed end, means to admix a limited amount of air with said fuel in said pretreatment tube and means adjacent the open end of said pretreatment tube adapted to distribute fuel-air mix eluent therefrom into said combustion tube.

4. A jet combustion burner comprising an air tube, a burner tube of smaller diameter than said air tube and coaXially mounted within said tube, a pretreatment tube mounted within said air tube with at least a portion thereof located within said burner tube, means defining a passageway through which air may be admitted to said pretreatment tube, an ejector nozzle mounted in said pretreatment tube adapted to admit a continuous stream of fuel into said pretreatment tube such that a proportionate amount of air insuicient to support combustion is induced to ow therein, means for providing fuel to said nozzle, means defining an exit at the end of said pretreatment tube within said burner tube located near the upstream end of said burner tube, inlet means for admitting air into said burner tube to burn continuously therein the pretreated fuel emitted from said exit, and means defining an outlet at the downstream end of said burner tube to permit the passage of combustion gases therefrom.

5. In a jet combustion burner, an air tube and a combustion tube coaxially mounted therewith, said combustion tube being closed at its upstream end, orifice means located near the closed end and spaced along the length of said combustion tube to admit air thereto, at least one elongated pretreatment tube terminating within said combustion tube near the closed end thereof, and additionally being arranged for indirect heat transfer between products of combustion and contents of the pretreatment tube for a substantial portion of the length of the pretreatment tube, means to admit fuel to said pretreatment tube near its inlet end, inlet means to admit a limited amount of oxygen containing gas to mix with the fuel in said pretreatment tube, and outlet means for combustion gases at the rearward end of said combustion tube.

6. In a jet combustion burner, an air tube and a combustion tube coaxially mounted therewith, said combustion tube being closed at its upstream end, orifice means located near the closed end and spaced along the length of said combustion tube to admit air thereto, at least one elongated pretreatment tube, said pretreatment tube lying at least partially within the combustion tube and terminating therein near the closed end thereof, and additionally being arranged for indirect heat transfer between products of combustion and contents of the pretreatment tube for a substantial portion of the length of the pretreatment tube, means to admit fuel to said pretreatment tube near its inlet end, inlet means to admit a limited amount of oxygen containing gas to mix with the fuel in said pretreatment tube, and outlet means for combustion gases at the rearward end of said combustion tube.

DONALD P. HEATH.

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

UNITED STATES PATENTS Number Name Date 85,663 Hill Jan. 5, 1869 408,644 Wilson et al Aug. 6, 1889 438,513 Wilson et al Oct. 14, 1890 471,361 Rogers Mar. 22, 1892 1,310,927 Reichhelm July 22, 1919 1,509,706 Bryan et al. Sept. 23, 1924 2,398,654 Lubbock et al Apr. 16, 1946 2,398,883 Clarkson Apr. 23, 1946 2,438,858 Lindsey et al. Mar. 30, 1948 FOREIGN PATENTS Number Country Date 151,503 Switzerland Mar. 1, 1932

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