US1581351A - Method of and apparatus for burning pulverized fuel - Google Patents

Description

April 20 1926. 1,581,351

H. KRE ISINGER ET AL METHOD OF AND APPARATUS FOR BURNING PULVERIZED FUEL Filed Dec. 30, 1920 3 Sheets-Sheet 1 iven 14w W/Mfff. I I A A TTORNEYS.

April 20 1926. 1,581,351

H, KREISINGER ET AL METHOD OF AND APPARATUS FOR BURNING PULVERIZED FUEL &

ATTORNEYS.

L r 1,581,351 April 2 2 KREISINGER ET AL I METHOD OF AND APPARATUS FOR BURNING PULVERIZED FUEL Filed Dec. 50, 1920 s Sheets-Sheet 5 v ATTORNEYS.

Patented a rizo, 192s;

UNITED STATES PATENT OFFICE...

HENRY KREISINGER, OF PITTSBURGH, PENNSYLVANIA, JOHN ANDERSON, 0]? MIL- WAUKEE, WISCONSIN, AND JOHN E. BIZJIIVOF BROOKLYN, N EWsYORK, ASSIGNORS TO COMBUSTION ENGINEERING CORPORATION, A CORPORATION OF NEW YORK.

, METHOD or AND APPARATUS FOR BURNING PULVERIZED FUEL.

' .Application filedlDecember-30,1920. Serial 1:6.433391.

tion.

provision of improvements whereby it is possible to increase, in a furnace of given size, the space utilizable for combustion purposes. Anot-her of the objects is to increase the combustion rate and make it possible to burumore coal in a furnace of given size.

Still another object is to control the direction of flame travel insuch .manner that a furnace deep but comparatively narrow in its horizontal dimension along the line of the boiler tubes may be used with efficiency. This is 01 great' advantage since the practical limitations of modern boiler-house design are such that but little or no space in front of the boilers is available for extensionto in crease furnace volume, .while there is considerable space available vertically due to the fact that the boilers are set high relative Our invention also contemplates the pro fvision of improvements 'whereby natural draft is utilized to the fullestpossible extent and the amount-of compressed air 1ncidently requiredreduced to a minimum so as to increase efficiency by eliminating the power requirements for forced draft and reducing the power requirements for compressed air.

Another object of our invention resides in the provision of'improv'ements by means of.

This invention relates to a method of andv apparatus for burning pulverized fuel and. v it has for one of its principal objects. the

to the floor line and are provided with amburnt successfully whereby the expense of pulverizing is cut down, in the one instance, and the expense of drying machinery avoided, in,the other instance.

More specifically, our invention contemplates the provision of improved burner mechanism for pulverized fuel burning furnaces, especially such asare used for generating steam, by means of which the'fuel is admitted, and burned iii a thin, wide, sheet-like stream, "approximately continuous acrossthe, combustion chamber, such burner vertically prismoidal furnace, and air for combustion. bQlIlgZSUPPllGd in such manner as to secure ob ectS-and advantages herein set forth. Our invention additionally remechanism being used in combination 'with a 1 ties as to secure maximum efiiciencyin com-' bustion. v

The foregoing, together with such other objects'and advantages as ma hereinafter appear or are incident to our invention, we

obtain by a methodand apparatus disclosed in preferred form- "in 'the accompanying.

drawings, wherein Figure 1 is a longitudinal section through a wateritube'boiler furnace illustrating our improvements- Figure Zisa front elevation of the'furnace; Figure 3 is a longitudinal section through one of the burners employed in carrying out our invention, drawn on an enlarged scale Figure Lisa section. of the eferring now furnace, indicated as a whole by the referto Figures 1 and 2, the

.burner taken on the line H of Figure 3 ence letter A, comprises the combustion chamber B, WhlCh is preferably vertically prismoidal and has an outlet 7. in the upper part or region thereof, preferably in the top; the boiler C, in this. instance of the water tube type, set'so as to extend over the outlet? for the products of combustion; and the burners D which are preferably mounted subject the fuel to its radiant heat. Each burner consists of a casting 11, somewhat like an elbow, in which depends a burner nozzle comprising the nozzle proper 12 and the member 13 hung on t e upper part of the casting 11 which is suitably apertured to permit of the introduction of the'burner parts. The nozzle 12 is flared out from the top toward the bottom, from a somewhat oval to a. flat cross section, the opening 12" in the lower portion being wide in one di-' mension and narrow in the other. The open ing in the member 13 changes from a circular to an oval section. The burner may thereforebe described as of a fish tail type. A delivery pipe 14; is connected with each of the members 13., The burner nozzle 12 terminates above the lower end of the castside of thenozzle nearest the boiler.

ing,so that the stream of fuel, which is discharged therefrom in the form of a thin, wide sheet approximately parallel the front wall of the combustion chamber, may be surrounded by air'as will now be described.

Located withinihe casting 11 is avertical wall or septum 15; such wall being on trhlat 1e upper end of the wall 15 ispreferably somewhat below the inlet 16 of the casting, while the lower portion of the wall terminates short of the-lowerend of the casting- The interior of the casting is thus divided into two chambers a and b communicating with the space a at the top. The burner nozzle thus extends into chamber 6, and to control the air supplied to 'such chamber we provide a pair f dampers 17 cut out so as to fit around he burner nozzle and operated by the worms 18 and segments 19. By manipuiation' of suchdampers the amount of air supplied to chamber 6 around the nozzle and therefore around the fuel stream may be regulated for a'purpose which will appear.

' This inxturn effects somewhat of a regulation of the air passing through chamber a.

Another damper 17 controls the inlet to the space 0 of the casting. Thus the air supplied at the draft side. of the fuel delivery nozzle 12 canbe separately" regulated (in a practical sense), since it can be varied both in absolute amount and relatively to any air supplied at the other side of the nozzle and the fuel stream.

Additional air for combustion is also sup- I plied through the front wall of the combustion chamber at a plurality of points, as by means of the damper controlled inlets 20. The air thus admitted at 20 serves to cool and protect the front wall, and to afford a cooling zone in the bottom of the chamber B beneath the combustion zone, for preventing fusing together of the falling particles of ash or slag,as is well understood in this artfi The'operation is as follows, assuming that the furnace is hot enough to maintain ignitionz The burners deliver a mixture of fuel and air to be hereinafter described in a' series of juxtaposed thin sheet-like streams which are surrounded by induced air and which almost immediately unite to form a substantially continuous sheet across the width of the combustion chamber. This ignites, and the flame is spread across the combustion chamber so that the surface in contact with the air and the surface exposed to'the radiant heat ofthe furnace and for initial combustion is a maximum for the furnace width.

-As a result, the rate of combustion is increased and it is'possible to burn more coal in a furnace of given size and also to ignite and burn readily coarser coal than heretofore. The streamof fuel and flame is turned upwardly by the draft so that it .takes a substantially U-shaped course in the combustion chamber, the combustion beingpracti'cally completed therein and the products of combustion then passing amongst the boiler tubes. W

Since the fuel and flame stream, particularly the descending part thereof, is in the form of a sheet extending across the combustlon chamber, 1t is advantageous to supply' so'me of the additional air needed for 'combustionon the exterior of the fuel sheet through theopenings 20, and other' uantit1es 1n the interior, that is between t 1e descending and ascending portions of the fuel and flame stream. This latter is accomplished by the chambersa through which streams of air are induced by the furnace draft, adjacent the incoming fuel and air.

This additional airthus does not have to pass through the stream of fuel and flame and does not therefore break up the stream lines. All the air required is supplied substantially above the bottomof the chamber, so that an effective cooling zone can be established in its lower region, even with considerable variation of flame level.

Another and very important advantage of this arran ement is that the depth of the flame travel, 1. e. the level of the base of the flame may be altered as desired, and the flame may be caused to sweep down well toward the bottom of the combustion chanr. ber, thereby increasing the volume of space utilizable for combustion purposes. To drive the flame downward and thus lower the lVe prefer.

dampenl'i' in a fixed position.

flame level (so to term ithin the combustion chamber B, it is only necessary to increase the downward momentum ofthe inv the flame, and its extent away from its point,

of admission increases the space in the furnace actively used and made available for combustion. This is diagrammatically indicated in dotted lines in Figural, Again if the .flame impinges on the furnace floor the damper 17 is partially closed and the dampers 17 opened. Or these same results may be accomplished by manipulating the furnace draft and dampers 17 leaving Further, it will be seen that by delivery and burning of the fuel in a thin sheet, the descending and lascending portions of the fuel and -fiame stream can be broughtmore, closely together, and when. this" is coupled with the fact that the sti'eamcan be made to turn approximately at any desired "level, it will be observed that it is possible to efliciently burn pulverized fuel, in a furnace which is .deep but narrow in horizontal width in the line of the boiler tubes, tl at is to say in a furnace in which volume 1s secured by depth more than by width. Thus pulverized fuel equipment may be effectively installed without exceeding the limitations imposed by standard boiler-house design.

It will also be observed that the ability to bring the descending and ascending portions together promotes more effective and more rapid combust1on -because the former portion is more intimately subjected to the heat of the latter' portion, this being particularly advantageous in the burning of anthracite coal. The eflectiveness of this feature willbe better appreciated when it is-co'nsidered 3 that the length of the descending and aspending portions ofxthe stream may be increased.- to admit the mixture of fuel and'air at a velocity such that, in the absence of the additional air, the-flame will not reach the bottdin portion of the furnace, and then to induce the additional air by thedraft and regulate the air supply in the manner indicated .so as to lower the flameyto the desiredlevel, the additional air being sup.- 1 plied, at less velocityso as to. produce an eddyaction-adapted to bring fresh supplies 3 of air, in contact with thenfuel and flame.

, Tobe more specific, the additional air, ad

mitted aroundfithe fuel stream and the air ;in relative velocities.

admitted on the, inside of the fuel and flame stream is supplied atless velocity so that eddies will be produced by the 'jference The .air admitted "through the openings 20 is also at lower 1 velocity. so that it will tend to fellow and border the stream lines of the fuel and flame and provide a body of air into, which the heavier particles'of, fuel not consumed or only-partially consumed will gravitate and be burned. v f

The method and apparatus are such thatit is unnecessary to provide for d draft, the natural draft being adequate to secure maximum efiiciency. Thus there is a minlmum interference with natural stream lines, blow torch action is eliminated and at no time is there an impingement of suflicient forceto cause running or flowing of the refractories.

Furthermore, we'have found that by our process and apparatus it is necessary to supplyonly a small proportion of the air re; quired for combustion with the fuel delivered to the burners, say for example 10% or less, and this illlflSl-lOlll Cl be supplied at a' low pressure, just suflicient forv it .to act as a carrier. Thus, the usual power requirements for the forced draft'are eliminated, and the incidental requirements fo fuel carrying air are reduced to a minimum, the total saving over stroker practice being Sufiiciently great to pay for the cost of pul verizmg.

In this latter connection, it is to be observed that the shape of the burner is such as to break upthe-particles of coal which stick together when the coal is not dried, this together with the large surface exposed making it possible if desired, to burn coal having a higher percentage of moisture than usual, the final combustion of such coal being secured by the other advantages incident to our invention and heretofore noted. Wye claim: K 1

1; The method of burning pulverized fuel in suspension in a furnace having an outlet in an upper"part thereof, which consists 1n i troducing'and.igniting the fuel in a down-- 'WELI'Clly directed stream so that the fuel and flame stream'must take a U-shaped course through the combustion chamber to said out-. let, in admittingparallel to said stream and in juxtaposition thereto on each side there of a stream-of combustion-supporting air, 11

stream, adjacent the firstmentioned stream of air and between the descending and as-.

cending legs of the U, to' control the level at,,which said fuel and flame stream turns upwardly. I

2. In combination with a pulverized fuel' burning furnace aving an outlet in an up, per'part,'a" burner, positioned to admit the I fuel downwardlyfand comprising a casing, D having. an upper receiving portion and a lower discharge portion, a septum positioned I v V longitudinally of said casing and dividing the discharge portion thereof into two passages, one of which is between the furnace outlet and the other passage, a fuel nozzle, greater in one cross-sectional dimension than in the other, extending through the upper receiving portion of said casing and into the passage most remote from the furnace outlet, an air inlet in the casing adapted to admit air into both of said passages, a damper for said inlet, and separately regulable dampers one on :each side of the fuel nozzle in the passage into which the nozzle extends.

In testimony whereof' I have hereunto signed my name.

HENRY KREISINGER.

In testimony whereof I have hereunto signed my name.

JOHN E. BELL.

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