US1496913A - Pulverized-fuel burner - Google Patents

Description

.Fijne l0, 1924.` `1,496,913

JN. L. WARFORD PULVERIZED FUEL BURNER Filed March 19, 1920 Patented io, ieee.

NORMAN LEW WARFORD, OF ALLENTOWN, PENNSYLVANIA., ASSIGNOR T .1 2' LEHIGH COMPANY, A CORPORATION OF PENNSYLVANIA.

P'ULVERIZED-FUEL BU To all 'whom 'it may concern.'

Be it known that I, NORMAN LEW WAR- FoRD, a citizen of the United States, residing at Allentown, in the county of Lehigh, State of Pennsylvania', have invented certain new and useful Improvements in Pulverized- Fuel Burners; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a pulverized fuel burner particularly adapted for use in connection with apparatus for producing an initial mixture of fuel and air and feeding it to the burner.

An apparatus of this character is shown in my Patent No. 1,147,833, issued July 27, 1915. Briefly described, this apparatus comprises a supply hopper communicating with a casing within which is a screw conveyor and from which the pulverized material is discharged in the form of a thin sheet parallel to the axis of the conveyor.

Means are rovided for subdividing the fuel sheet and delivering it into a mixing chamber within which is an air blast nozzle, which lby an injector action induces a current of air through the mixing chamber t`o pick up the fuel and carry it into the zone of action of the air blast, by which it is then projected to the point where it is to be burned.

It is an object of this invention to provide a` pulverized fuel burner particularly adapted for use with a feeder and mixer such as is shown in my patent to produce an absolute and thorough mixture of fuel and air which shall enter the combustion chamber at low velocity and may be accurately controlled to maintain the required temperature substantially constant. While the urner of the invention is intended particularly for use with the feeding and mixing apparatus of my patent, it may be used in combination with otherv forms of apparatus forproducing a preliminary mixture of air and fuel.

naccordance with the invention the burner comprises a tip which is adapted to be imbedded in the wall ofA a furnace and is designed to allow expansion of the fuelladen airand produce aA thorough mixing of its constituents as they enter the furnace. Communicating with the tip is an air chaml ber which is designed and proportioned so as to impart a whirling or cyclonic motion to the air as it advances through-the chamber. Within the chamber is Ia nozzle into which a mixture of air and fuel may be supplied from a suitable mixing apparatus, such for instance as that of my prior patent. The discharge end of the nozzle is tapered and provided with a number of narrow longitudinal slots through which a portion of the fuel mixture is discharged substantially normal to the nozzle and in position to be picked up and mixed with the air passing from the chamber to the tip of the burner. This mixture also tends to mix with the fuel laden air discharged from the open end of the nozzle, thereby producing a thoroughly mixed and uniform column of fuel laden air, which enters the combustion chamber at relatively low velocity. For convenience the air for the chamber of the feeder and mixer and the air for the chamber of the burner may be supplied from a common source.

The particular nature of the invention, as well as other objects and advantages thereof, will appear more clearly from a description of a preferred embodiment as lshown in the accompanying drawing, in

which, Fig. 1 is a longitudinall sectional view of a burner combined with a feeding and mixing apparatus like that of my patent mentioned above, Fig. 2 is a transverse section taken through the casing 3, the cham'- ber or pocket 8 and one of the conduits 9, and Fig. 3 is a sectional view of the casing 25 illustrating one form of construction of the casing and the air inlet thereto for producing the whirling or cyclonic motion of he air as it advances through the air 'cham- The apparatus comprises a hopper 1 into which the pulverized fuel is supplied from any suitable source and from which the fuel.

is discharged in regulated quantities through a valve or gate 2 into a casing 3 within which is a screw conveyor 4l mounted in suitable bearings 5 and 6 at the ends of the casing and adapted to be driven from any suitable source of power (not shown) bottom of the casing is rovided with a narrow longitudinal slot through which the fuel may be discharged in a thin stream into an openended pocket 8 from which the fuel-then passes through a series of tubes or conduits 9 eounieating at their lcwer tov of the chamber and terminating at its inner end beneath the bottom of a large pipe 12 leading from the extreme end of the casing 3 beyond the slot 7. The nozzle 11 is bolted to one end of casing and additionally braced by a strap or'hanger 13 attached to the casing 3. The outer end of the nozzle is provided with a tapering extension 14 to which is connected a branch pipe 15 leading to a conduit 16 through which an air blast may be supplied from a blower or other suitable apparatus. The quantity of air supplied lto the nozzle 11 may be controlled bymeans of a damper 17. The wallsof the mixing chamber 10 iare outwardly as at 18, and this end of the mixing chamber is provided with free air intake openings 19 controlled by a suitable damper 20. f

The other end of the mixing chamber carries a taperingextension 21 to which is attached a pipe 22 leading to the burner of the present invention. This burner) comprises a tip 23 in the form of a cast iron ring which may be of round oroval form walled into a correspondingly shaped opening in the wall 24 of the furnace. The tip should preferably be provided with a flaring inner end which lits within a conical portion of the opening in the furnace wall. Attached to the outer end of the tip is a casing 25 constituting an air chamber and which is designed and proportioned so as to cause the air entering-the chamber to have a whirling motion as it advances into the tip of the burner. The casing 25 is provided with a tapering extension 26 for receiving a sleeve 27 leadlng to the conduit 16, the extension 26 being inclined or tangentially directed in accordance with one form of construction as illustrated in Fig. 3 for producing a cyclonic or swirling motlon of the air in the ,casing 25. The extension 26 may be provided with a damper 28 by which the amount of air entering the casingmay be controlled. The rear Wall of the casing is provided with' a number of peep holes 29 normally closed by a plate 30 slidably mounted upon the outer face of the wall. The rear wall of the casing is also provided with a central aperture throu h which extends a nozzle 31 held in place y a flange 32 adapted to be attached to the wall of the casing; The outer end of the nozzle 31 enters the pipe 22 leading from the mixing apparatus. The inner end of the nozzle is tapered, and this tapered portion is provided with narrow, longitudinal slots 33 of suflicient number and area when taken in combination with the opening at the end of the nozzle to permit the fuel-laden air supplied by the mixing apparatus to be discharged from the nozzle in suicient quantity to meet the requtrements of the furnace tenacia Tn the operation of the apparatus described abovethe powdered fuel falls from the hopper 1 into the casing 3 in an amount determined by the position of the valve or gate 2. As the fuel enters thecasing 3 it is advanced by the screw conveyor and falls through the slot 7 in a narrow stream. Any

material that does not fall through the slot is carried forward to the intake end of the pipe 12 and drops into the inner end of the mixing chamber. This pipe prevents clogging of the fuel in the'casing 3 if, for any reason, it should fail to escape freely through the slot 7. After passing through the slot the material falls through the open ended pocket 8 into the pipes 9 which spread and subdivide the material so that it becomes more thoroughly mixed with the air which is drawn in through the apertures 19 by the injector action of the air blast supplied to the nozzle 11 from the conduit 16. The amountof airinduced through the apertures 19 may be controlled by the damper 20, and the strength of the airblast may be controlled by the damper 17. Since the ends of the pocket 8 are open a current of air will always be induced through the pocket and be drawn withl the fuel as the latter flows through the tubes 9. The fuel therefore receives its initial mixture of air at the intake ends of these tubes, or as it leaves the slot 7 This initial installment of air, together with the quantity induced through the openings 19, insures a sufficient amount of air in connection with the air supplied at the burner to e'ect complete combustion of the fuel as it enters the furnace.

The fuel-laden current of air in the mixing chamber 10 comes into the zone of action of the air blast from the nozzle 11 and together with any fuel which may fall through the pipe 12 is rojected through the pipe 22 into the nozz e 31 of the burner. 0n account of the arrangement of the slots 33 in the tapering end of the nozzle, some of the fuel-laden air will be discharged substantially normal to the surface of the nozzle and become thoroughly mixed with the air which is supplied to the casing 25 from the conduit 16, the amount of this air being llllli controlled by the damper v28. The intery mingling of the air and fuel is further aided by the cyclonic motion imparted to the air in the casing 25 by the shape of the latter, or by the inclination of the air inlet as described. Tf at any time it is desired to observe the burning `fuel within the furnace the peep holes 29 may be uncovered, but in the normal operation of the apparatus these holes will be closed to prevent any possibility ofleakage of air and fuel from the casing 25.

`With the apparatus described above the pulver-ized fuel and air are intimately mixed in. the chamber 19 and then projected into L, :y

the nozzle 31 from which they issue in such a manner as to become thoroughly mixed lwith additional air supplied through the casing 25. The amount of air supplied to the fuel at each of the points 'where mixture takes place may be independently 'controlled by means of the dampers 17 and 28 supplemented by the damper 20 which controls the extent of opening of the ports 19 in the Wall of the first mixing chamber. By producing a preliminary mixture of fuel and air and then introducing at another point the additional air required for complete combustion the velocity of the fuel and air as it enters the furnace is reduced and the fire may be accurately controlled to produce the required temperaturein the furnace.

While the burner o f the invention is particularly adapted for use with a feeder and mixer such as is shown inv my Patent No. 1,147,838, and is so shown in 4this application, it will be understood that it may be successfully used with other forms of mixing apparatus and also that various changes in the details of construction of the burner may be made without departing from the principle of the invention as defined in the appended claims.

I claim 1. A fuel burner comprising a casing provided with an extension adapted to be attached to the Wall of a furnace, a tapered nozzle Within the casing provided with a plurality of longitudinal slots near its discharge end, meansff'or supplying to the nozzles a mixture of fuel and air under pressure, the taper of the nozzle being such as to obtain a discharge of a portion of the fuel and air mixture atan angle to the axis of the nozzle, and independently controlled means for supplying air to the casing to mix with the mixture discharged from the nozzle and to carry the same'into the furnace, the said means including an inlet into the casing so formed as to produce a cyclonic hmovement of the air as it passes throu h the casing and into the furnace.

2. fuel burner comprising a casing adapted to be attached to the Wall of a furnace, a nozzle Within the casing having an inner taperin end4 provided vwith a plurality of longltudinal slots, means for supplying a mixture of fuel and air to the nozzles, the taper of the end of which is such as to obtain a discharge in part through said slots at substantially right angles to the axis of the nozzle, and means for supplying air to the casing to mix with the fuel and air discharged from the nozzle and convey,

the same into the furnace, the said means including an inlet into the casingv tangentially disposed with relation to the casing 'whereby to produce acyclonic movement of Q the air as it passes through the casing into the furnace.

3. A fuel burner comprising a casin provided with an extension adapted to e attached to the Wall of a furnace, a tapered nozzle within the casing provided-With a plurality of longitudinal slots near its dis-` charge end, means for supplying a mixture of fuel and air to the nozzle the taper of the nozzle being "such as to obtain a discharge in part through said.slots at substantially right angles to the nozzle, and means for supplying air to the casing to mix with the air and fuel discharged from the nozzle and carry the same into the furnace, said casing and air inlet being formed to producea cyclonicy movement of the air as it passes through the same to carry the'fuelinto the furnace. A f

4. In apparatus for burning pulverized fuel, the combination of a fuel supply chamber, a mixing chamber, means for conveying fuel from the supply chamber and discharging it into the mixing chamber, an

air supply conduit, means for directing air from the conduit to the mixing chamber, a casing communicating with the furnace, a

tapered nozzle Within the casing connected v to the mixing chamber and having a plurality of longitudinal slots near its discharge end, and means for supplying ,air to the casing to mix with the fuel and air discharged from the nozzle and convey the same into vthe furnace, the said means including an inlet through which the air enters the casing, this inlet being so formed as to produce a cyclonic movement of the air as it passes through the casing into the furnace.

5. In apparatus for burning pulverized fuel in a furnace, the combination of a chamber, means for supplying fuel to the chamber, a conical nozzle within the chamber, a second nozzle connected to the discharge end of the chamber and having-a tapered end provided with a plurality 'of longitudinally disposed slots near this end, a casing surounding the second nozzle and communicating with the furnace, and means for simultaneously supplying an air blast to the first nozzle and to the casing to carry the.

fuel from the' chamber into the casing through the second nozzle and to' carry the mixture offuel and air issuing from the slots and the end of the second nozzle into the furnace, the said means including a conduit communicating with the first nozzle and a second conduit provided with a damper and connected to the casing by an inlet tangentially disposed with relation to the cas, ing 'whereby to give the air entering the casing through the inlet a cyclonic movement through the casing.

`6. In apparat-us for burning pulveri'zed fuel, the combination of a chamber, ymeans for supplying fuel to the chamber, a nozzle Within the chamber, means for supplying air to the nozzle to mix with the fuel and conasv vey the latter from the chamber, a nozzle connected with the discharge end of the chamber and having a tapered, slotted end, a casing adapted to be attached to the Wall of the furnace and surrounding the nozzle last mentioned, and' independently controlled means for supplying air to the casing at a point to the rear of the slots of said nozzle, this means lncluding an air inlet into the mettere.

the fuel and air mixture issuing from saidV slots, and thereafter with the mixture issuing from the end of said nozzle.

ln testimony whereof l affix my signature.

NRDIAN LEW WARFRD.

Images