US1959864A - Fuel feeder - Google Patents

Description

May 22, 1934. o. A. HARTLEY FUEL FEEDER Filed Nov.

23, 1928 2 Sheets-Sheet May 22, 1934.

O. A. HARTLEY FUEL FEEDER Filed Nov. 23, 1928 2 Sheets-Sheet Patented May 22, 1934 FUEL FEEDER.

Orland A. Hartley, Tampa, Fla.

Application November 23, 1928, Serial No. 321,340

14 Claims.

My invention relates to improved mechanism for delivering regulated quantities of pulverulent fuel such as powdered coal, oil or gas, properly mixed with regulated quantities of air, through a nozzle to the combustion chamber of a rotary kiln, steam boiler or the like.

Generally stated, the objects of my invention are, first, the provision of improved devices for effectively regulating the rate of supply of the fuel, second, the provision of mechanism for controlling the quantity and direction of flow of an oxidizing agent such as air and for effectively mixing the air with the fuel, and third, the provision of a simple and efficient nozzle for finally delivering the combustible mixture into a combustion chamber. I

Considerable difiiculty has heretofore been encountered with mechanisms for feeding combustible mixtures of pulverulent fuel and air to the combustion chambers ofrotary kilns when used in the manufacture of Portland cement where the production of high grade cement is largely dependent upon the maintenance of definite and uniform temperatures within the several zones of the kilns. With the prior mechanisms, it has been practically impossible to accurately control the fuel supply so as to maintain a well regulated fuel feed at all times. The prior fuel feeders would either choke readily, or else they would overfeed at times, thereby creating extremely undesirable conditions of operation and producing poor economy of fuel consumption. The air supply devices of the prior fuel burners, while being to some extent adjustable so as to regulate the quantity of air admitted, did not permit effective mixture of the air with the fuel prior to delivery thereof to the combustion zone. In addition to these defects of the prior fuel feeders, the fuel injection nozzles heretofore employed did not insure most efiective delivery of the combustible mixtureto the burning zone at all times, with the result that the devices of the prior art were relatively ineflicient and detrimental to the production of cement of best quality.

All of the above mentioned defects of the prior fuel feeders or burners, are entirely eliminated with my present invention, which although especially adapted for use in connection with rotary cement kilns, is also capable of other uses. The improved fuel feeder not only enhances the economy of fuel consumption, but positively prevents fiooding or overfeeding and substantially prevents choking of the feed. The air supply device of the present improvement is capable of effectively mixing the fuel and air, and is controllable to deliver the mixture to various longitudinal and lateral portions of the combustion chamber. The improved nozzle is also specially constructed to maintain effective discharge of the mixture for a long period of time, thus producing a combination of elements which meets all desirable demands. a

The more specific objects and advantages 0 my invention, and the manner in which devices embodying the features thereof may be constructed and operated, will be apparent by reference to the drawings accompanying and forming a part of this specification wherein the various parts are designated by suitable numerals.

Fig. 1 is a part sectional side view of my improved fuel feeder' showing thesame associated with the firing hood of a rotary kiln. I

Fig. 2 is a somewhat enlarged transverse vertical section through the fuel feeder, the section being taken near the delivery end of the air supply nozzle.

Fig. 3 is an enlarged longitudinal section through the delivery end of the fuel conveyor and the fuel flow regulator.

Fig. 4 is a fragmentary top view of the improved fuel feeder.

Fig. 5 is a diagrammatic transverse vertical section through the fuel supply bin and. through the twin fuel feed screws.

Fig. 6 is an enlarged fragmentary sectional view of the air control mechanism, the section being taken transversely through the delivery end of the air supply nozzle.

Fig. 7 is another fragmentary sectional view of the 'air control mechanism, the section being taken off-center and longitudinally through the delivery end of the air supply nozzle.

Fig. 8 is still another fragmentary sectional view of the air control mechanism, the section being taken longitudinally through the delivery end of the air supply nozzle at right angles to that of Fig. '7.

As previously indicated, my improved fuel feeder consists generally of fuel supply mechanism, air supply mechanism, and a nozzle for delivering the combustible mixture of fuel and. air to the combustion zone of a kiln or the like. These several elements will be described more in detail in the order mentioned.

My improved pulverulent fuel supply mechanism comprises a fuel supply bin 3 which is adapted to receive the fuel from a supply device 2 located above the bin, and to deliver the fuel by gravity to a pair of similar conveyor screws 7 past adjustable fuel control plates 26, these plates being manipulable by means of levers 2'7. Located within the bin 3 directly beneath the discharge opening of the supply device 2, is a distributing cone 4, and below this cone is located an upright wall or diaphragm 5 which prevents the fuel from arching over the lower portion of the bin 3 and insures proper delivery of fuel to the conveyors '7. The screw conveyors 7 are rotatable at variable speeds, by means of driving mechanism 10 cooperating with the conveyor supporting shafts 40, and are iapable of urging the fuel delivered from the bin 3 through substantially parallel conveyor casings 6 toward a common fuel discharge chamber 12. The lower end of the supply bin 3 is provided with removable closure plates 38. and the casings 6 are provided with removable plugs 34, for permitting access to the conveyor screws 7 throughout their lengths.

Associated directly with the conveyor shafts 40 at the delivery ends of the screws 7, are enlarged screw or vane sections 11 rotatable in enlargements of the casings 6 which may be provided with clean-out slides 32. The pitch of the screws or vanes of the sections 11 may be such as to form either a single spiral flight as shown, or an annular series of inclined vanes, depending upon the rate at which they are to urge the fuel forward. The fuel discharge chamber 12 is disposed at the delivery end of the conveyor sections 11, and is separated from the enlarged casings of these sections by means of adjustable fuel fiow regulators. Each of the fuel fiow regulators comprises a stationary slotted or perforated plate 16, an adjustable slotted or perforated fibre plate 15 cooperating with the plate 16 to vary the effective area of the perforations thereof, and a rotary slotted or perforated plate 14 secured to the adjacent shaft 40 and movable in close proximity to the plate 15. The adjustable plates 15- are preferably formed of fibre to prevent formation of sparks, being provided with elongated marginal slots 36 coacting with positioning screws, and as shown, these plates have their adjoining peripheral portions provided with intermeshing teeth 35 as shown in Fig. 2. In order to permit simultaneous adjustment of the plates 15 from the exterior of the chamber 12, one of these plates may be provided with an integral handle 33 movement of which will simultaneously adjust both plates 15 equal amounts.

The fuel discharge chamber 12 which receives the fuel in regulated quantities from both of the conveyor screws 7, has a single outlet 17 at.

the bottom thereof and is also provided with an adjustable air inlet 13 at its top. The inlet 13 which in fact constitues a secondary inlet for air, is controllable by means of a slide 3'7 pivotally associated with the wall of the chamber 12. The interior of the chamber 12 may be segregated into two compartments by means of a wall or diaphragm 8, so as to permit continued operation of one of the screws 7 while the other is stopped.

My improved main air supply and mixing device comprises a feed pipe 22 into the medial portion of which the mixture of fuel and air is delivered from the chamber 12 through the outlet 17. An air injection nozzle 18 is associated with an end of the pipe 22 and has its delivery end disposed centrally within the pipe 22 just in advance of the outlet 1'7 of the chamber 12, the nozzle being thus centrally supported by means of centering lugs 39; A fan or blower 19 is operable to deliver air at high velocity to the nozzle 18 which by virtue of its constricted discharge end, delivers the air centrally through the pipe 22 in the form of a high velocity jet. In order to vary the inte sity of the air jet delivered from the nozzle 18, and also to insure thorough mixing of the air and fuel, the delivery end of the nozzle 18 is provided with an annular series of angularly adjustable vanes 20 supported by pivots 30 secured to the nozzle casing. The forward portions of the vanes 20 are secured to corresponding ends of actuating links 28 the opposite ends of which are pivotally attached to a rotatably adjustable shifting ring 29 which is rotatably slidably supported upon the reenforced endof the nozzle 18. The ring 29 is angularly adjustable from the exterior of the pipe by means of an adjusting handle or lever 21 extending through a slot in the pipe 22 which is sealed at all times by plates 31 as shown in Figs. 6, '7 and 8. By shifting the lever 21, the angularity of the vanes 20 may be readily changed, thereby producing variable whirling motion of the jet delivered from the nozzle.

My improved combustible mixture discharge or burner nozzle comprises a laterally adjustable tapered nozzle portion 9 supported upon the discharge end of the pipe, and an adjustable ring or orifice element 23 secured to the delivery end of the portion 9. The delivery end of the nozzle portion 9 is laterally shiftable to a limited extent in any direction relative to the end of the pipe 22 by virtue'of a loose fit between the coacting ends of the pipe 22 and nozzle portion 9, thereby permitting variation in the direction of discharge of the mixture of fuel and air, and the enlargement of the cross-sectional area of the nozzle portion 9, somewhat decreases the velocity of the combustible mixture prior to final discharge thereof. The removable element 23 is formed in halves clamped to the nozzle end, and

may be adjusted along the nozzle portion 9 and may even be reversed, for the purpose of maintaining a relatively clean-cut delivery orifice at all times. The element 23 may be formed of material which will resist wear and extreme heat,

and which will prevent'formation ofundesirably jagged edges. The delivery end of the burner nozzle is directed through a firing hood 24 longitudinally of the rotary kiln 25, although the combustion chamber may be that of a steam boiler or any other type of heat utilizing device.

During operation, my improved fuel feeder functions as follows:-The pulverulent fuel which ordinarily is pulverized coal, is precipitated upon the distributing cone 4 within the bin 3 by the supply device 2 and is distributed 1i in substantially equal proportions on opposite sides of the diaphragm 5. The fuel thus admitted is permitted to accumulate within the lower portion of the bin 3 without packing to a sufllcient extent to insure proper fuel supply at all so as to permit more effective passage of the par- 1 ticles through the regulators. The loosened fuel masses are eventually pressed against the Stationary plates 16 the effective area of the perforations of which has been fixed by adjustment of the adjacent plate 15. As the plate 14 rethrough relatively large openings insures uniform volves in close proximity to the relatively fixed perforated plates 15, '16, the fuel is permitted to flow in expanded condition and at a uniform rate, into the chamber 12 where it is intimately mixed with the air admitted through the opening 13, and from which the mixture passes downwardly through the outlet 17 to the pipe 22.

Upon entering the pipe 22, the mixture of fuel and air is brought in contact with the main air jet issuing from the nozzle 18 and is rapidly i transported by the jet toward the burner nozzle.

Y for the purpose of extinguishing fire.

Depending upon the setting of the vanes 20, the air jet issuing from thenozzle 18 has more or less whirling motion, thus producing thorough mixture of the air and fuel as they pass through the pipe. 22. When the combustible mixture reaches the flaring section 9 of the burner nozzle, the velocity thereof is somewhat diminished, and the mixture is finally delivered into the combustion chamber of the kiln 25 where it is ignited and burned.

With the various adjustments provided, various conditions of the combustible mixture and considerable variation in the position of the combustion zone, are obtainable. The quantity of fuel may be accurately determined by merely adjustment the plates 26, or by shifting the plate 15, or by varying the speed of the screws '7. The quantity of air may be accurately controlled by adjusting the position of the plate 37, or by con-= trolling the operation of the blower 19. The position of the combustion zone may be, changed by varying the speed of'the blower, or by adjusting the vanes 20 to vary the degree of whirl of the jet, and thedirection of the jet may be readily altered by swinging the nozzle portion 9 about the end of the pipe 22. It will thus be apparent that maximum fuel economy is attainable by simple adjustments of the mechanism, and that the feeder is especially applicable wherever variation in the position of the burning zone and accurate regulation of the fuel are desirable.

The twin feed is important as it enables operation of the feeder at approximately one half of its normal capacity, in case one of the feed screws 7 is disabled. When "this occurs, the disabled screw may be disconnected from the driving mechanism 10, its feed plates 26 may be closed, and the screw removed. The removable plates 38 and the plugs 34 also permit convenient access to the screw casings for the removal-of large lumps of fuel, for the release of choke-ups, or The slides 32 also facilitate removal of undesirably large particles and serve as clean-outs. The wall 8 and the diaphragm 5, besides insuring uniform distribution of the fuel, eliminate arching of the fuel across the respective chambers within which these elements are located. The distributing cone 4 cooperates with the diaphragm 5 to insure uniform distribution of the fuel, and thus also aids in the production of a homogeneous final mixture.

The use of a fibre or similar regulating plate 15 adjoining the rotary plate 14, eliminates fire hazard by preventing sparking which might result from striking of metal plates against each other. As shown, each of the regulating plates 14, 15, 16 is provided with six equal radial slots which are of. substantially the same width as the metal strips between the slots. With the slots of the plates 15, 16 fully opened, fuel will be d livered to the chamber 12 six. times during each revolution through openings the total area of which is approximately one half of the total conduit area. This intermittent delivery of fuel discharge of fuel in desirably loosened condition for mixing with the air, and positively avoids flooding or overfeeding.

My improved fuel feeder has proven highly satisfactory in commercial operation in the cement industry, and has effected an actual saving of at least five pounds of coal per barrel of cement, and an increase in total production of more than ten percent. The improvement has eliminated flooding of coal through the feeder, has done away'with smoke nuisance, and has provided'a means for maintaining uniform heat in the various zones of the-kilns.

While I have shown one embodiment of the invention which is especially applicable to rotary cement kilns, it will be apparent that the device is capable oi considerable modification within the scope of theappended claims.

What I claim as my invention is:-

1. In combination, a storage bin, a rotary screw conveyor for delivering pulverulent fuel from said bin, a stationary perforated plate at the discharge end of said conveyor through the perforations of which the fuel is delivered, means cooperable with said stationary plate to vary the effective area of the perforations, a perforated rotary plate cooperating with said stationary plate to retard said delivery of fuel, and means for producing an air jet for discharging the fuel gravitating from said plates to a combustion chamber.

2. In combination, a source of fuel supply, a rotary screw conveyor for delivering pulverulent fuel from said source, a stationary plate at the discharge end of said conveyor having perforations through which fuel is delivered by said conveyor, an adjustable plate cooperating with said stationary plate to vary'the effective area of said perforations, a rotary member movable across said perforations to retard the free passage of fuel therethrough, and means for producing an air jet for discharging the fuel delivered past said rotary member to a combustion chamber.

3. .In combination, a source of fuel supply, a rotary screw conveyor beneath said source and communicating with an enlarged discharge chamber, adjustable means for controlling the discharge of pulverulent fuel from said source to said conveyor, a revolving fuel loosening vane associated directly ,with the discharge end of said conveyor within said chamber, a rotary perforated member at the end of said chamber remote from said conveyor through the perforations of which the fuel is delivered by said loosening vane, and means for producing an air jet for discharging the fuel passing said rotary member to a combustion u communicating with an enlarged discharge chamber, means for supplying pulverulent fuel to one end of said conveyor, a revolving fuel loosening vane associated with the opposite end of said conveyor within said chamber, a stationary plate having an annular series of perforations through which the fuel is delivered from said. chamber by said loosening vane, a member movable across said plate perforations to retard the free passage of said fuel, and means for producing an air jet for discharging the fuel passing said member to a'combustion chamber.

5. In combination, a rotary screw conveyor communicating with an enlargeddischarge chamber, means for supplying pulverulent fuel to one end of said conveyor, a vanerevolvable with said conveyor within said chamber for loosening the stationary plate having a series of perforations through which said fuel is delivered from said chamberby said loosening vane, an adjustable plate cooperable with said stationary plate to vary the effective area of said perforations, a perforated member rotatable with said conveyor for retarding the flow of fuel through said plate perforations, and pneumatic means for discharging the fuel passing said member to a combustion chamber. w

6. In combination, a plurality of conveyors for pulverulent fuel simultaneously operable from a common source and communicating with a common enlarged discharge chamber, means for independently controlling the delivery of fuel to each of said conveyors, loosening vanes movable within said chamber, a -stationary perforated plate beyond said vanes and said chamber in alinement with the discharge end of each of said conveyors through the perforations of which the fuel is delivered, a perforated .rotaryplate cooperating with each of said stationary plates to retard said delivery of fuel, and means for producing an air jet for receiving fuel from said conveyors and for delivering the same to a combustion chamber.

7. In combination, a plurality of oppositely rotatable screw conveyors operable from a common source and communicating with a common enlarged discharge chamber, means for supplying pulverulent fuel to said conveyors, a revolving fuel loosening vane associated with the delivery end of each of said conveyors within said chamber, a perforated plate beyond said chamber through which fuel is delivered by each of said distributors, a member movable across each of said plates to retard the free passage of fuel therethrough, and means for producing an air jet for discharging fuel delivered past both of said members to a combustion chamber.

8. In combination, a screw conveyor, a stationary perforated plate at the delivery end of .said conveyor, means for varying the effective I delivery end of said conveyor, a stationary perforated plate for receiving fuel from said loosening vane, a perforated rotary plate cooperating with said stationary plate to retard the delivery of fuel from said conveyor, and means for producing a flow of air in proximity to said plates for delivering the fuel passing saidrotary plate to a combustion chamber.

.ifuel delivered from the opposite end thereof, a J ,10. In combination a plurality of conveyors operable from a common source, means for delivering fuel to said conveyors, a revolving fuel loosening vane associated ,with the delivery end of each of said conveyorsand disposed within an enlarged discharge chamber common to both of said conveyors, a stationary perforated plate cooperating with each of said vanes to control the delivery of fuel therefrom, a member movable across each of said plates to retard the free passage of fuel therethrough, and means for producing a flow of air for discharging the fuel passing said member to a combustion chamber.

11. In combination, a plurality of screw condelivery of fuel to said conveyors, a stationary perforated plate at the discharge end of each of 12. In combination, a conveyor, a wall having perforations exposed to the delivery end of said conveyor, means for varying the efiective area of said perforations, a perforated member movable with said conveyor and cooperable with said wall to retard the delivery of granular material by said conveyor through said wall perforations, and means for producing a flow of gas in proximity to said member for discharging the material de-' livered from said perforations to a placeof uti-\ lization. J

13. In combination, a conveyor, a fixed wall having perforations exposed directly to the delivery end of said conveyor, adjustable means for varying the effective area of said perforations, a perforated movable member cooperable with said wall to retard the delivery of granular material by said conveyor through said wall perforations, and means for producing*a flow of. gas in proximity to said member for discharging the material delivered from said perforations to a place of utilization.

14. In combination, a rotary conveyor, awall having perforations exposed directly to the delivery end of said conveyor, rotatably adjustable eans for varying the effective area ofsaid perf rations, a perforated member rotatable by said conveyor and cooperable with said wall to retard the delivery of granular material by said conveyor through said wall perforations, and means for.

producing a flow of gas beneath said member for discharging the material delivered by gravity from said perforations to a place of utilization.

, ORLAND A. HARTLEY.

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