US1976208A - Fuel burner - Google Patents

Description

Oct. 9, 1934. F. T. AGTHE ET AL FUEL BURNER Filed April 24 HHHH Patented Oct. 9, i34

UNITED STATES Y PATENT OFFICE FUEL BURNER Application April 24, 1931, Serial No. 532,410

7 Claims.

This invention relates in general to the art of fuel burners and relates more particularly to a burner in which the flame is adjustable. More specifically it relates to a combination of a material-receiving furnace and a burner for adjustably associating therewith a iiame compris-- ing a combustion supporting gas and a gaseous, liquid 'or pulverized solid fuel, to permit of an eflicient heat-transfer between said flame and said furnace and its received material, primarily to be heated. The burner disclosed is especially adaptable for use with a gas high in hydrogen content. The fields of application of the above novel combination. comprising this invention includes broadly those of the ceramic, metallurgical, household heating by means of air or liquid heating agents, and kindred elds. And although the invention has been illustrated in connection with a rotary kiln, such as used in the cement industry for calcining of clinkering raw cement materials, this is understood to be illustrative rather than limiting, and obviously the furnace need not be a rotary furnace.

An object of the invention is to provide a construction as above related, in which the gases to constitute the flame are fed to the burnerunder pressure, the burner orifices being adjustable to permit changing the static pressures of the gases to velocity pressures, while maintaining the requisite ratio of these gases to properly support the combustion thereof with the aid of a certain amount of secondary air.

Another object of the invention is to provide in a construction, as above set forth, the intimate and effective mixing of the gases to constitute the name after delivery thereof from the burner.

Another object of the invention is to provide the burner of the construction, as related above, with means to impart to the gases helical motions of projection from the burner.

Another object of the invention is to provide a construction, as related above, in which the burner supplies a portion of the air necessary for combustion, known as primary air, and serves as an aspirator to induce the additional required amounts of secondary air to complete combustion of the gaseous fuel projected from the burner.

Another specific object of the invention is to provide a construction, as related above, in which the gases are admitted to the burner at pressures permitting the adjustment of the velocity heads at the orifices of the burner in a manner such that the rate of projection of the gaseous fuel may be made greater than the rate of propagation of a gaseous fuel having a high rate of ame propagation so that backiires or explosions within and ahead of the burner are effectively prevented when burning a gas having this characteristic.

Another object of the invention is to provide a construction, as related above, and including a substantially stationary burner provided with means for projecting a flame having its hottest point at the portion of a cooperating furnace at which the greatest heat is required.

A further specic object of the invention is to provide a construction, as related above, in which the burner is designed to project an annular column or envelope of air at high velocity and traveling in a helical path, with a high velocity gaseous fuel column therein and also moving in a helical path, to avoid early diffusion of the gaseous fuel after projection from the burner, the burning of the fuel close to the burner, and whereby a partial vacuum tends to form between the two gaseous columns to intimately mix the projected gases in addition to the mixing action produced by the spiraling of said gases.

Other objects and advantages of this invention will be apparent from a consideration of the specification and of the drawing accompanying the same and forming a part thereof and on which like reference numerals are used to designate the same elements throughout the various views.

Fig. ,1 is a fragmentary vertical, longitudinal section through the lower or discharge end of a rotary furnace such as used in the cement industry for calcining cement and shows the novel burner of the novel construction forming this invention associated therewith.

Fig. 2 is a fragmentary cross-sectional view ,taken at right angles to the view of Fig. 1 above the burner thereof.

This invention relates, as stated before, in a general way, to improvements in the art of drying`, sintering, calcining and fusing materal in a rotary kiln used in the ceramic and metallurgical fields by the use of a gaseous liquid or pulverulent fuel with varying amounts of primary air and varying lengths of flame.

In rotary kilns used in the above named arts, it is usual to admit with the gaseous fuel a certain quantity of air, primary air, to support incipient combustion,the necessary additional quantity of air being induced by the expansion of the products of combustion resulting Yfrom the incipient combustion. It is generally arranged so that the primary air or the air introduced with the gaseous or pulverulent fuel is minimized in -quantity to economize in power that 'would otherwise be necessary to move the large volume of air required for completing combustion. In the improved arrangement or combination of this invention, the primary air is introduced with the fuel and supplied in a suicient volume and under sumcient pressure to permit regulation of the point at which the ame reaches its maximum intensity at a distance from the burner and at the same time this introduction induces sufficient additional air which is thoroughly-mixed with the fuel to make complete combustion possible.

The flame in a rotary kiln gives up its by radiation and convection and transfers heat to the charge therein, as it-moves to the lower or discharge end of the kiln, while in the bottom of the kiln, as well as, to the lining which in turn gives up its heat to the charge as it passes beneath the charge.

In order to make most effective the heat-transfer from the flame to the charge, it is necessary that the light gases do not fiow to the top of the kiln and that the gases be turbulent or passing not only over the charge, but also around the lining, which is best accomplished by imparting to the gases rotary or spiral motions so that they traverse the interior of the kiln in helical paths. Further, according to this invention, the primary air is preferably introduced at a higher static pressure than the gaseous fuel so that in all degrees of orifice or nozzle regulation the velocity of the air is greater than the velocity of the gaseous fuel, the air thereby forming an envelope of air around the gaseous fuel tending to keep the lighter gaseous fuel, a gas rich in hydrogen, to the burning of which type of gaseous fuel this invention is especially applicable, and which is a light gas by reason of its high hydrogen content, from rising too rapidly to the top of the kiln. And the velocity of projection of the gas, rich in hydrogen and of low specific gravity, is also greater than the rate of flame propagation for this gas to further prevent the occurrence of flashbacks which might cause the undesired ignition of all the gas in the supply pipes ahead of the burner. The invention further makes it possible to effect an intimate mixing of gas and air, additionally because of the formation of a partial vacuum between the projected concentric columns of spiraling gas and air.A

In order to impart the above recited rotary or spiral motions to the gases to constitute the flame, both the gas and the air are introduced into the burner through elbowsat right angles to the direction of the flow of these gases in the main portions of the burner. By introducing the air and the gas into the burner in the describedand illustrated manner, the change of direction which the gas and air undergo in passing into the burner imparts a rotary motion to these gases so that as they leave the burner upder the influence of the pressure within the supply pipes they will progress spirally within the kiln. By reason of these motions the gases are more intimately mixed, the gas with the primary air, and permits of a more thorough admixture with the secondary induced air as above described to further tend to effect complete and efficient combustion.

Having now set forth the nature and objects of this invention and explained the principles underlying the same, a specic embodiment thereof and illustrated in Figs. l and 2 will now be described in detail. Reference numeral 1 indicates a rotary kiln slightly inclined so as to permit material being heat-treated therein to move to the shown lower` or discharge end there of, and 2 is a firing hood associated with this end. As is usual, the hood may be provided with a refractory lining 3 and the kiln similarlywith a refractory lining 4. In order to facilitate the withdrawal of the hood from the lower end of the kiln, the hood 2 is provided with wheels 5 traveling on rails 6. The bottom of hood 2 between the wheels 5 is provided with a usual disheat charge opening, not shown, for receiving the heattreated material and forA the admission of secondary air into the kiln 1, as is well understood in the cement industry. The hood 2 is provided with an opening '7 opposite the end of kiln 1 to receive the improved novel burner of the novel construction constituting this invention, which burner is designated generally by reference numeral 8. The burner 8 is adjustably and pivotally associated with the wall of hood 2 which contains the opening 7 by means later to be described. l

The burner comprises an inner nozzle 9 and a concentric outer cooperating nozzle 10. The inner nozzle 9 is formed by a hollow cylindrical member having one end or" reduced diameter providing a throat portion 1L and having its other end connected to a flanged elbow 12 in such a manner that its center line with the axis of the hollow cylindrical member forming the inner nozzle 9 determine substantially a plane for purposes later to appear. Another flanged elbow 13 is connected to elbow 12 so that its center line lies in substantially a plane at right angles to said plane above described. The concentric outer nozzle 10 is formed by a cylindrical member, spaced concentrically from the cylindrical member of inner nozzle 9 and has a frustoconical portion 14 adjacent the throat portion l1 of inner nozzle 9, and has at its other end a composite elbow 15 arranged like the elbows 12 and 13 of the inner nozzle 9. The composite elbow 15 is provided with an opening to concentrically receive the inner nozzle 9 and the intersecting surfaces of nozzles 9 and 10 are welded together to seal the joints formed therebetween. The inner nozzle 9 has a bulb type of movable nozzle element 16 cooperating with the throat portion 11 and said bulb 16 has an axially reciprocable stem 1'7, passing through elbow 12, and being guided by a perforated disk 18. In order to seal the joint between the stem 17 and the elbow 12 a stuffing box and gland 19 are preferably associated with the elbow 12, the gland thereof being further formed to provide a pair of radially spaced guides 21 and an axially spaced internally threaded drive sleeve 22 which receives the threaded end of stem 1'7, a handwheel 23 being secured to the stem 17 to facilitate the rotation thereof. It is apparent that by moving the bulb 16 in or out the effective area of orifice opening of nozzle 9 may be adjusted. The outer nozzle 10 is similarly provided with a ring 24 for adjusting the effective area of its orifice opening through means of a pair of diametrically opposed parallel rods 25 rotatively secured thereto at one end. Intermediate portions of the rods 25 have secured thereto exteriorly threaded collars 26 cooperating With the internal threads of a pair of forgings 27 secured as by welding in sealed relation to the nozzles 9 and 10 and in alinement with the openings in nozzle 1G which receive rods 25. The screw means 26 forms an effective means for sealing these openings against gas leakage. The rods 25 are further passed through openings in the flange of elbow 12 and guided by the guide members 21. In order to prevent binding of the ring 24 on the reduced cylindrical portion of inner nozzle 9, the rods 25 are simultaneously rotated through common means. This means comprises a handwheel 28 at the end of one of the rods 25, a sprocket 29 spaced therefrom on said rod and a chain passing over said sprocket and over another like sprocket 30 on the other rod 25.

cresce The flange construction of elbow 12 is provided to facilitate withdrawal thereof from the remaining portion of the burner so far described,

for purposes of cleaning the bulb le', etc.

In order to effect swinging and adjusting of the burner construction so far described, away from its receiving opening 7 and with respect thereto, a jib crane is hinged to a hood front-wallreenforcing construction including Z-bars 31 and a plate 65, on a vertical axis passing through,

hinge element 32, see Fig. 2. This jib crane coinprises an upper substantially horizontal member 33 and a diagonal bracing member 34 carrying a gusset plate and therethrough upper and lower apertured supports 36, apertured to receive a pin 37 extending centrally from a perforated f disk-shaped forging 38. A similar and perforated disk 79 is secured to on'e of the forgings 27 of burner 8 and really forms a part thereof, the planes of the disks 38 and 79 being adiustable to provide various angles therebetween and to provide corresponding tiltings of the burner 8 by means of adjusting bolts connecting said disks. This adjustmentdsofevalue irconnection also with the proper attachment of the gas and airv at a pressure greater than atxnosplzleric;Y Thepressure may be 14/i4nchesvov/vater when firing withbrmproductrcoke oven gas and may be pro- /f/J/duced by means of a centrifugal fan 41 having a flywheel 42 to store up certain amount of rotary kinetic energy, for purposes presently to appear. The fan 41 may be supported by a bracket 43 from the plate 65 secured to the firing hood 2. The fan is shown as being driven by a three phase alternating current motor having power leads 44 thereto and a switch 45 in thwewleads. The winding 46 of an electromagnet having'a heavy cooperating armature 47 which also serves as a weight meansff'r actuating a Vpawl, as `will later appeazz'lis/ constantly energized as long as the switch 45 is closed and the electrical power supply to the motor isv intact. a link which freely and pivotally receives one arm of a bell crank 48, the other arm 49, of which serves as a catch member. The catch member 49 normally engages a cooperating catch 50 of a link 5l secured to and so as to rotate with a buttery valve 52 controlling the ow of gas through gas supply pipe 39. Upon failure of the source of electrical power for the motor driving fan 41, the weight of armature 47 will cause catch 49 to disengage the cooperating catch 50 permitting a weight carrying member 53 freely pivoted to link` 51 at one of its ends, to move the valve 52 to 'its closed position. This automatic means is inserted as a precaution against explosions when the air supply fails with failure of the electrical supply, the gas supply being soon thereafter cut on, and what gas passes to inner nozzle 9 prior to the time of full closure of the valve 52, is withdrawn and mixed with air supplied to the outer nozzle 10 and subsequently burned, due to the continued rotation of the fan as measured by the moment of inertia of its flywheel 42. Thus a scavenged gas nozzle and cooperating passage to the gas valve 52 is automatically provided after each stopping of the motor driving ian 41.

An actual construction of the disclosed novel The armature 47 has combination ofi burner and rotary kiln has now been in practical and successful operation for some period of time and has been found to provide as une a quality of cement as when using pulverulent fuel when using by-pro'duct coke oven gas, which gas has a high hydrogen content and a low speelde gravity, and, therefore, being a high in hydrogen gas Within the meaning of this invention.

By-produc't colre oven gas as made from Beck# er type Kcppers oven may contain the following analysis:

Percent N f. 6.1) H2 --.T 47.3 02 -2.- 0.3 CO 6.8 CO2 2.2 CHQ 33.9 C2H2 2.4 CSHG 1.1

Specific gravity 0.436 Specific heat per pound at constant pressure 0.65l Specic heat per pound at constant volume 0.491

Weight of a cubic foot of gas in pounds--- 0.0332

Each cubic foot of gas requires 5.27 cubic feet of air and the caloric value of this gas is 580 B. t. u. per cubic foot.

With the novel burner of this invention a kiln which was heretofore capable of burning 1700 barrels of clinker per day of twenty-four hours when using coal, now requires in order to burn 110 the same amount of clinker with by-product coke oven gas that the burner handle 3000 cubic feet of gas per minute under conditions of standard pressure and temperature. Owing to the high percentage of 'hydrogen H2 (47.3), this gas is extremely light and has a high rate of flame propagation, approximately 29 feet per second. And as the .calorifc value of by-product coke oven gas is low, about 580 B. t. u. per cubic foot, see the above analysis, a large volume of this gas must be burned to give the caloriflc value in the burning zone `necessary to properly burn the clinker. In the referred to commercial construction of the disclosed novel combination of rotary kiln and novel burner, about one-fourth of the air required for combustion of the required amount for burning by-product coke oven gas is admitted through the outer nozzle 10 and is known. as already referred to, as primary air, and is forced through the nozzle 10 at such a pressure that it produces a high velocity envelope of air through which the by-product coke oven gas, passing through the orice of inner nozzle 9, does not readily permeate or at least not until 'the coke oven gas has traveled some distance from the burner. Because of the low specific gravity of this gas, it was found necessary to project the gas into the kiln for a distance of between fteen and twenty feet, within the surrounding high velocityenvelope of air, so that the flame would not burn up against the burner but would have its maximum name intensity at a point fifteen to twenty feet from the lower end of the kiln which is known as the burning zone, and'thereby permit the burning of the clinker to conform to the ordinary practice of burning clinker with coal. Accordingly, a fan 1l-with a static pressure at the fan of about 14 inches of water is used with a specific volume, to provide about 25 percent of theoretical air required for combus- 15 tion, and the by-product coke oven gas is supplied at a pressure of about 12 inches of water to the nozzle 9. v

Further, in burning cement clinker it is necessar'y to control not only the quantity of fuel, but also the position of the flame with reference to the burning' zone. This further necessitated the admission of he by-product coke oven gas into the inner nozzle 9 at a pressure of approximately 12 inches of water.

Ordinarily it would probably be better to use the disclosed two nozzle burner in combination with a rotary kiln for burning cement with a gas, if the gas is admitted to the nozzle 9 and the primary air which may be one-fourth of the total air to support the combustion of the required value of gas, is admitted to the outer nozzle 10. The disclosed burner it is to be understood is not limited solely to this order of gas reception and many cases are conceivable where it would be desirable to admit the primary air into the inner nozzle 9 and to admit the gas into the outer nozzle 10, especially where it is beneficial to have a short hot llame.

By moving the nozzle elements the static pressures of the gaseous fuel and ofthe combustion supporting air are changeable, at will, to velocity pressures, so that the length of the flame may be increased or decreased depending upon the ratio of velocities of air to gas. The gas supply pipe 39 may be provided with a valve and an air valve may be provided between the fanv 4l and the burner 8 and be connected to a regulator in the gas supply pipe 39 so that the value of the air delivered to the burner is constant even with fluctuations in pressure of the gas in the gas supply pipe. In the practical installation above referred to, the bulb 16 is movable toward closed position no further than to cut off 90 percent of the full area of the nozzle.

Although the disclosed novel combination has been described with reference to the use of gaseous fuels, generally, and more specifically with gases having high hydrogen contents and low specific gravities, it is not limited thereto,

' since liquid fuels and'pulverulent fuels, such as powdered coal, could also be admitted either into the inner nozzle 9 or into the outer nozzle 10. but probably preferably through the inner nozzle 9, with substantial beneficial results.

It is to be understood that it is not intended to limit the invention to the exact details herein shown and described, for various modifications within the scope of the claims may occur to persons skilled in the art.

It is claimed and desired to secure by Letters Patent:

l. A burner means adapted to be associated with a furnace, including a plurality of nozzles having adjustable annular orifices and multiple elbow inlets, for projecting regulatable concentric columns of spiraling gases of pressures greater than atmospheric.

2. A burner adapted to be associated with a furnace, said burner including inner and outer concentric nozzles having regulatable annular orifices direc-ted in a common axial direction and having multiple elbow inlets, and means for supplying air and a fuel under pressure to the respective inlets of said nozzles.

3. A burner adapted to be associated with a furnace, said burner including inner and outer concentric nozzles having adjustable annular orifices directed in a common axial direction and having multiple elbow inlets, means for supplying air under pressure to one of said inlets, and means for supplying a fuel under pressure to the other of said inlets, the orifices being adjustable to change the static pressures of the air and of the fuel to velocity pressures, to vary the length of flame resulting from the combustion of the fuel supplied to one of said inlets.

4. In a gaseous fuel combustion appliance for forming a mixture of two iiuids projected considerable distances into the interior of a combustion chamber. an outer nozzle having an inwardly inclined annular orifice portion, a nozzle arranged inwardly of and concentrcally to said outer nozzle and having an annular orifice portion surrounded by said outer nozzle, an adjustable ring member having a surface complementary to the inclined annular surface of the orifice portion of said outer nozzle, to regulate the area of the eiiective orifice of said outer nozzle, and an adinstable nozzle element to regulate the -area of the orice of said inner nozzle, and multiple elbow inlets for supplying the two constituents of a combustiblglgasegus iiuid mixture separately to said outer nozzle and said inner nozzle, said inlets eiiecting spiraling of said gases said nozzles in order that they may be projected from the appliance in the form of spiraling concentric columns of gases to provide effective mixing of the gases exteriorly of and remote from the appliance.

5. In a burner, an inner nozzle having a multiple elbow inlet, an outer nozzle arranged outwardly of and concentric to said inner nozzle, the outer nozzle having a multiple Y,elbow inlet, the annular side walls of the thus related nozzles providing annular oriiices remote from said inlets, axially displaceable annular outer regulating means for adjusting the area of the annular oriflce of said outer nozzle, interior axially displaceable regulating means for adjusting the area of the orifice of said inner nozzle, and operating means for said regulating means.

6. In a burner 'especially adaptable to the burning of -a gas rich in hydrogen, an inner nozzle having a multiple elbow n'etan outer nozzle arranged outwardly of and concentriesto said inner nozzle, the outer nozzle having a multiple elbow inlet, the annular side walls oi the thus related nozzles providing annular orifices remote from said inlets, axially displaceable annular outer regulating means for adjusting the area of the annular orifice of said outer nozzle, interior axially displaceable regulating means for acljusting the area of the orifice of said inner nozzle, and operating means for said regulating means.

'1. In a burner especially adaptable to the burning of a gas rich in hydrogen, an inner nozzle having a multiple elbow inlet, an outer nozzle arranged outwardly of, surrounding and concentric to said inner nozzle, the outer nozzle having a multiple elbow inlet, the annular side walls of the thus related nozzles providing annular orifices remote from said inlets, said annular orifices being directed substantially in a common axial direction along the parallel axes of said nozzles, axially displaceable annular outer regulating means for adjusting the area of the annular orifice of said outer nozzle, interior axially displaceable regulating means for adjusting the area of the orifice of said inner nozzle, and operating means for said regulating means.

FRED T. AGTHE. RAY C. NEWHOUSE.

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