US1532041A - Pulverized-fuel burner - Google Patents

Description

March 31. 1925. L 1,532,041 D. H. COUCH I PULVEBIZED FUEL BURNER Filed Mar h 16, 1922 4 Sheets-Sheet 2 "Dal/dd /X Ga e/z March 31. 1925.

532,041 D l-l. COUCH Fil Ma h 16, 192 2 4 Sheets-Sheet awn M01 March 31. 1925. I 1,532,041 D. H. coucH PULVERIZEDFUEYL BURNER Filed March 16, 1922 fishnets-Sheet 4 amen/[1oz citizen of the United States, residing Patented Mar. 31, 1925.

UNITED STATES 1,532,041 PATENT OFFICE.

DAVID E. COUCH, 0F WARWICK, RHODE ISLAND.

PULVEEIZED-FUEL BURNER.

Application filed March '16, 1922. Serial No. 544,198.

To all whom it may concern:

through the burner under a slight pressure,

part of said air being blown or sucked in with the pulverized fuel and acting as a vehicle or conveyor for said fuel and the remainder of the air for combustion, or secondary air, being forced in through suitable openings in the burner, so as to form an intimate and thorough mixture of air and fuel, thus making possible the complete combustion of the fuel in furnaces of small "olume. v

A particular object of my invention is to provide ameans for obtaining a thorough mixture of air and fuel in the immediate vicinity ofthev burner tip. This object is accomplished by placing a diffuser or spreader in the discharge end of the fuel pipe to spread the suspended fuel into a thin sheetor hollow com; and force it past suitable streams of air Thisf 'diifuser may be applied-to fuel pipes of any shape or form and may be used with any type of air admission for secondary air, butythe preferred embodiment of my invention is that shown on the accompanying drawings and consists of acircular fuel pipe flared at the discharge end andprovided with a cone shaped diffuser for spreading tliiestrearnpf fue form a thin hollow cone or blast of fuel suspended inair and drive it approximately parallel with theinner surface of a truncated cone composed of alternate solid sections and slots, the secondary air for combustion being admitted through said slots an'dmixed with the fuel. "l Other objects will appear in the specification andclaims appended thereto.

The preferred design of this truncated cone is. that shown on the drawings and.

consists of. sections or segments of refractoryv or fire-res1st1ng material between which slots are'provided for the admission and air as it leaves the outlet, so as -to- F ig. 6 is a of secondary air. Theseslots may be placed at any angle, preferably at approximately ninety degrees to the radius of the inner' surface of the truncated cone, so that the secondary air will be directed approximately tangentially to the inner surface of the truncated cone, and thus produce a rotating or whirling motion of the fuel and airand form a thorough mixture of the same. Provision may be also made for the admission of additional secondary air around and parallel with the discharge end of the fuel pipe, should this be found necessary or desirable at certain rates of combustion.

The preferred embodiment of my invenaccompanying burner, showing theimeans employed for spreading the suspended fuel into a thin hollow cone and forcing it past the secondary air openings in the truncated cone of the burner;

Fig. 3 is a vertical transverse section through the truncated cone on the line 3-3, Fig. 2, showingthe angular setting of the sectionsor segments which make up the truncated cone of the burner and form the air space;

i Fig. 4 is a vertical longitudinal section through the fuel pipe, diffuser and diffuser supports;

Fig. 5 is a detail view showing the lever for operating the spreader adjusting mechanism;

section on the line 66, Fig.

4, lookmmthedirection' of the arrow; and

Fig. 7 is a furtliersection on line Fig. 4, looking in the direction of the arrows,

Referring to Fig. 2, 1 is the fuel pipe, the horizontal portion of which isv called the burner section, through which the pulverized fuel is'blown suspended in air, only a small percentage of the total air re uired for comustion being blown in the uel. The discharge end'l of the fuel pipe is flared and provided with a conical diffuser or spreader 2,.the purpose of which is to spread the fuel into a hollow'cone and direct it approximate ly parallel with the inner surface of a truncated cone 3, which is preferably made up of sections 4 of refractory or fire-resisting material which are removable as units and artime force it toward the axis of the truncated cone 3, thus producing an intimate and thorough mixture of air and fuel and causing a large part of the combustion to take place within the truncated cone 3 before the burning mixture passes on into the furnace. The parts 1, (1 2, 3, 4 and 5 above described constitute the principal parts of the burner and are attached within and housed by the steel windbox 6.

This windbox 6 contains air under a slight ressure supplied from the air duct 7, (see i ig. 1) through the connecting duct 8 into an equalizing chamber 9. Where several burners are used in connection with a furnace, each burner is separated from itsneighbor by a partition, preferably of sheet steel,

"forminglan air compartment for the burner, and each burner compartment is divided into two pressure cham-bers 10 and 11, wherein anv desired air pressure may be maintained by properly adjusting the dampers 12 and 13 which regulate the passages between the equalizing chamber 9 and the pressure chambers 10 and 11. The'pressure chamber 11 eommunicateslwith the interior o f jhe t nncated cone through passages 5 described above and chamber 10 through passages 10 and 3 as will be hereinafter set forth. The w'rndbox 6is made up of the steel framework 14, 15, 16, 17, 18, 19, 20, 21, 22,

23 and plates 24, 25, 26, 27, 28, 29, 30, 31 and 69, and for purposes of facilitating inspection and removal of sections 4 of the truncated cone 3, the plates 27 28, 29 and 30 are removable, being held in place by cap screws 36, and eachpair of plates, that is, each exterior plate and the interior plate immediately back of it, for instance 29 and 30, give access to approximately onefourth of the interior of each burner compartment. The sections 4 are secured to the angles 37 and 38 by the bolts 39 and 40, and the weight of the outer end of the burner with the parts attached to the angle 38 and the framemember 20, which is in'the form of a ring surrounding pipe 1, is carried by the bracket 41 attached to the angle 42 by cap screws 43 and resting on the floor 44 in frontof the remov- This,

able plate 27 All of the weight of the outer end of the burner is in this manner carried by the bracket 41, thereby permitting the removal of all of the removable plates without affecting the alinement of the burner.

The sections 4 of ,the truncated cone 3 are preferably each made of a refractory portion a, Fig. 3, supported'by a portion 6 of metal, such as cast iron, although these sections may be made entirely of cast iron or other heat resisting material. However, the refractory material is preferred as it is a poor conductor of heat and will, therefore, maintain a hotter zone for combustion. A fire brick circle 46 is provided about the larger end of the truncated cone 3 and is lined with blocks 45. The blocks are beveled correspondingly to -sections 4 of the truncated cone'and are slotted to form continuations of the air space 5. The blocks 45 are fitted tightly into the circle 46, are bonded in said circle by high temperature cement, and are therefore not removable with the sections 4. Leadin vertically downward from a source of fue su'pply, (not shown), is a fuel supply pipe 68* structed with a double curvature which is intended to overcome the tendency of particles of fuel heavier than air to be thrown by centrifugal force against the outer side of the curve and thus be discharged into the bottom of fuel pipe 1. The double curvature ofthe elbow causes these particles to continue in a direction practically tangential to the main curve and to be thrown into the center of fuel pipe 1' on leaving the elbow, thus facilitating mixing and preventing the fuel from being precipitated at the bottom of the fuel pipe. g V Thelcurvatureofthe fiared discharge end 1 of the fuel pipe is preferably such that a line tangentto said curve at the point of dis charge will be parallel to the inner surface of the truncated cone 3.

The spreader 2 consists of a conical sec tion 50, preferably of cast iron, having a refractory protecting cap 51 held in the base end thereof by means of machine screws 60. The spreader is carried in the flared end 1 of the pipe 1 by a rod 52 which is supported for longitudinal movement axially of the pipe 1 by means of wheels 55, 56

. sure.

' said air ports.

.draft burner, that is, aburner using air at a pressure higher than atmospheric pres- Snce, however, 1t 1s possible by creating a sutiiclently negative pressure in the furnace to draw in the secondary air at atmospheric pressure, this burner may also be used as a so-called Natural Draft burner, especially at the lower ratings.

' In all "of the figures referred toherein my invention is shown with the fuel pipe I mountedin a horizontal position, but fuel pipe 1. and therefore the center line of the burner may be mounted inany desired posi-. tion or in any type of furnace.

Many of the details of design of the mechanical features of my invention as set forth above are typical of what may be used, andthe same may bevaried as desired without departing from the s'pirit of my invention. 1

What is claimed as new is:

1. In a pulverized fuel.burner., a truncated cone-shaped member having airports,

afuel feed pipe discharging into the smaller end of said member; and a spreader in the discharge end of said feed pipe for directing the fuel at a predetermined angle past 2. Ina pulverized :fuel burner, a fuel pipe, a truncated cone surrounding and pro,-

jecting beyond the discharge end of said pipe andhaving ports in the walls thereof, and a spreader, in the discharge end of saidpipe for. directing the fuel past said ports at a predetermined angle.

' afrustro conical combustion chamber, the

3. A pulverized fuel'burner comprising walls thereof being provided with ports communicating with,.=a source of air supply,

a fuel feed pipe co-axial'with said combustion' chamber and a' conical spreader in the end of said fuel feed pipe fordlrec'ting fuel past said 'air ports in a-direction substan wall of said combustion tialy parallel with chamber.

4. In a pulverized fuel burner, a -.feed" .pipe, a conical spreader in the discharge end of said feed pipe,an'd a truncated cone member located in front ofsaid discharge end consisting of spaced: sections so posi tioned that the'passages formed tlferebetween will lie approximately the internal surface of sai cone member.

. and means "forldirectingair through said pasages.

. 5., In a pulverized fuel burner, a feed .pipe,

a conical spreader in the discharge end of said feed pipe, and a truncated hollow cone tangential to memberlocated in front of the-discharge end of said pipe, said member having passage- Ways formed therein for the introduction of secondary air, said air passages being so arranged as to direct'the streams of secondary air approximately tangential to the inner surface of the truncated cone.

6. In a pulverized fuel burner, a feed pipe for supplyinga current of fuel-charged air to'the burner, a conical spreader in the discharge end' of said fee -pipe, a hollow truncated cone member su rounding and extending beyond the discharge end of the feed pipe having passages in the walls thereof for secondary air, said passages being arranged to direct sa d secondary air mto the current the walls o'fsa'id truncated cone, and means whereby saidstre'am may be forced toward the axis of said cone; u

8.111 a pulverized fuel burner, a fuel feed pipe, a hollow truncated cone member located adjacent the,discharge end ofsaid fuel pipe, a spreader in the discharge endv of the fuel pipe adapted todirect the flow of fuel into said truncated cone, said trunc'ated cone having air passages leading thereinto for a supply of secondary air, the discharge end of the feed pipe and the adjacent end of the truncated cone member havingan opening therebetween for the supply of additional secondary air, and means for adjusting the size of said opening.

9. In combination with a pulverized fuel. burner, comprising a fuel pipe and a hollow truncated cone associated therewith at its discharge end, a wind box surrounding said burner, said wind box comprising an equalizing chamber and a pair of pressure chambers in communication therewith, said truncated cone havmg apertures'm 1ts walls affording 'eommilncation between the interior of the cone and one of the pressure chambers, and said truncated cone having a further aperture concentric with the fuel pipe and affording communication between the interior of the cone and the other pressure I chamber.

10. In combination with a pulverized fuel burner, comprising a fuel pipe and a hollow truncated cone associated therewith at itsdischarge end, a wind box surrounding said burner, said wind box comprising an equalizing chamber and a pair of pressure chambers in communication therewith, said trunon the base end 51of the spreader due,

for example, to an explosion in' the furnace, the spreader will be free to move rearwardly under pressure, thus closing the discharged end of the fuel pipe and preventing further feed of 'fuel into the furnace.

' The lever 61 is prevented from becoming disengaged from the rod 52 by means ofthe nut 58 and washer 59. This,.arrange-' ment makes the spreader 2 serve not only as a spreader and as a valve for regulating the size of the aperture at the discharge end of pipe 1" as set forth above,

but also, in case of serious explosions in the furnace, as an automatic check valve, the spreader 2 being free at all times to move backward in case the pressure in the furnace should suddenly become greater than the pressure in the fuel pipe.

In order to thoroughly mix theair and suspended fuel passing through the pipe 1, it is desirable to give the air aslightrotating motion in a direction counter to the direction of travel of the secondary air received through the passagescj. For this purpose vanes 64 are provided within the pipe 1 having propeller-shaped surfaces which cause the fuel in passing the same to rotate, and in order to regulate the mixing and rotation of the fuel flowing through the pipe, the vanes 64: are made adjustable. This is accomplished by forming the vanes with squared shanks 64 which are received and held by means of lock nuts 64' in the bores offrusto-conical sleeves 6 l which are rotatably mounted in complementary aper-.

.tures formed in the wall of the pipe. The

"till sleeves 64 may e provided with laterally extending handldlf l fgr rotating the vanes to various angular positions, in which positions the vanes may be secured by means of the lock nuts 64".

It is preferred that the surfaces of both the interior and exterior-of the discharge end of fuel pipe 1 be smooth, but either or both of these surfaces may be fluted or scalloped either longitudinally or spirally, if desired, to give better mixing.

At the rear end of the truncated cone 3 is a reentrant wall 3 which is provided with a central aperture 3 adapted to snugly receive the flared discharge end 1 of the pipe 1. It is desirable under certain circumtances to admit secondary air to the interior of the truncated cone in addition to that admitted through the passages 5, the amount of this additional air Varying with circmnstances- For this purpose the in- '1 terior of the truncated cone 3 is afforded communication with the pressure chamber 1 0 through the passages 10? between memtigers 10 and the through aperture' 3", the ia jperture 3 being regulated as to size or en tircly closed by proper axial adjustment of the pipe 1 ,in said aperture. The axial adjustment of the pipe 1 to regulate the aperture '3 is effected by providing an anpipe land is mounted for rotary movement relative'thereto and to cooperate with the complementary internally threaded part of.

an annular member 68 for moving the pipe nular adjusting. screw which encircles the backward or forward. ll1e screw 65 is se- 1 is brought back a short distance into the cast iron portion 3 of the small end of the truncated cone 3, whereupon the admission of air at this point, even if there should be spine leakage through the damper 12, is

practically shut off, On the other hand, if the admission'of air between thefuel pipe and the small end of the truncated cone 3 is desired, the adjusting screw 65 may be turned clockwise and the fuel pipe caused to move in towards the furnace until its inner end passes through beyond the central aperture 3 of the wall 3*. The fuel pipe 1, elbow 4:9 and fuel supply pipe (38 possess suflicient flexibility to allow for the above described movement, since the fuel supply pipe 68 is of considerable-length and the weight of these parts is carried on the sup port 73,]Fig. 1, which is attached to the elbow 42) bY bOlt 74 and rests in a recess in I a base member 7 5 attached to the floor 44 by cap screws not shown, or other suitable means. I

Fig. 1 shows the application of the invenshown mounted in the wall of the furnace .which supports, the blocks'45 and consists of fire brick or other refractory material 70, protected on the outside by the usual red or insulating briclc covering 77. The bridgewall 7 8 ,and all of the interior of the furnace are made of highly refractory mation to a powerplant boiler andthe various partsv of the burner described above are" terial, as forinstance, a high grade fire brick, to resist the intense heat of the furna'ce. floor 85, slag or ash discharge opening 86 which is connected withflthewater cooled slag tank 88 by the pipe 87, the rear, wall 89, back cpnnection fioor 90, and dust discharge pipe 91. The products of combustion pass. from the discharge end of the truncated cone 3 into the furnace and up among the tubes 79 past which they are drawn by the action of stack Or induced draft apparatus, the baffles 80 and 81 caus ingthese gases to pass a number of times Other parts of the furnace are the cated cone having apertures in its walls affording communication between the interior of the cone and one of the pressure chambers, saidtruncated cone having a further aperture concentric with the fuel pipe'land affording communication between the in-, terior of the cone and the other pressure chamber, "and means for adjusting the fuel pipe for regulating the size of or closing said last named aperture.

11. In combination with a pulverized fuel burner, comprisinga fuel pipe and a hollow truncated cone associated therewith at its discharge end, a wind box surrounding said burner, said wlnd box comprising an equalizi'ng chamber and a pair of pressure chain-- bers in communication therewith, said truncated cone havingapertures 1n its walls forming communication between the interior of the-cone and one of the pressure chambers, said truncated cone having a further aperture concentric with the fuel pipe and affording communication between the int'erior of the cone and the other pressure chamber, means for adjusting the fuel pipe for reg lating the size of or closing said last named aperture; and dampers controlling which fuel is blown suspended in air,- a hollow truncated cone having passages for the admission of secondary a1r, and a spreader in the discharge end of said fuel pipe adapted to spread the suspended fuel into a hollow cone and direct it at a predetermined angle past said passages, said truncated conecomprising sections of heat-resisting material spaced apart to form said air passages for the admission of secondary air in streams approximately tangential to the interior of said hollow truncated cone, an adjustable opening being formed between the discharge end of the fuel pipe and the small end of the truncated cone for the ad- 'mission of additional secondaryair.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses. l

' DAVID H. COUCH. Witnesses:

JACKSON Conn PHILLIPS, ARTHUR H. GORDON.

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