US1938137A - Pulverized fuel furnace - Google Patents

Description

Dec. 5, 1933. E. DIETZEL PULVERIZED FUEL FURNACE Filed March 12, 1930 2o burners adapted to be thrown'in .25; onstand-by or downhill run,

;35- and service by suchan 40 box.

50 nular surface of the burner or Patented Dec. 5, 1933 UNITED STATES.

1,933,137 PULVERIZED FUEL FURNACE Erich Dietzel, Cassel, Germany Application March 12, 1930, Serial No. 435,343, and in Germany March 22, 1929 4 Claims.

I My invention relates to an adjustable burner arrangement for pulverized fuel furnaces, more particularly intended for locomotives.

In contradistinction to stationary vboiler 5 plants, the yield demanded of a locomotive boiler is subjected tovery great variations at very short intervals, because for instance on stand; by or'during downhill run, the demand sinks to to a minimum amount while-in starting or during; uphill run, it increases very highly and quickly; These working conditions require a quick and eificacious adaptation of the furnace to the load of the fire chamber just prevailing, which adaptation in pulverized fuel. furnaces canbe attained in a very simple manner by regulation of the fuel quantities fed, which is effected by means of the fuel feeding device. To this end, hitherto, the pulverized fuel furnace has beensubdivided into several individual and out separately. First of all, however, it was necessary further, to provide in addition to this main burner an auxiliary burner, the object of which was tomaintain in times of low demand, that is the required boiler pressure and the flame, and neous re-ignition of the main burner for high demand. This auxiliary burner, however, requires not only a suitable place in the. the chamber but also separate ducts for the feed of air and pulverized fuel, a device for conveying thedust to the mixture duct and an agitating device with drive and control means. Now particular difiiculties are encountered both as to construction expensive appliance, which besides comprises agreat number of parts, more particularly in view of the restricted room conditions in the pulverized fuel container on the tender of the locomotive and also in the fire My invention therefore has for-its object to avoid these drawbacks by the fact that an auxiliary burner with appurtenant feed duct, conveying and agitating device, drive and control therefor are entirely abandoned; and that in the main burner duct 2. second burner duct is arranged concentrically, which can be cut off by a suitable blocking member, so that either the external, annular duct witlrthe appurtenant anthis external duct in unison with the internalone, that is the whole burner is operative. I further preferably so sub,- divide the sectional-areas of the ducts and the corresponding surfaces of theburner that the external annular, duct with theannular burner to secure instantasurface belonging thereto serves as an auxiliary burner, when the internal duct is cut off by the above blocking member. p In order, .further, that this inoperative central portion of the burner, which is then no longer cooled by the pulverized o fuel-air mixture passing'therethrough, is not in jured by re-radiation of the auxiliary flame and. of the .fire box, I prefer to pass cooling air through this inoperative duct. This cooling air is supplied through the blocking memberwhich, for this purpose, is hollow, and'iis'effected in such a manner that when the blocking member is set to closing position, the cooling air is automatically admitted.

I further provide only one single conveyor adapted to feed both the small fuel quantity for the auxiliary flame and the much greater fuel quantity'for the total burner. For the sake of adjustability, I provide a variable speed gear'in the drive of the conveyer, in order to reduce the 7 rate of revolutions of the latter when only the auxiliary flame is used, in accordance with the low fuel quantity required therefor. It will further be of advantage to couple with one another the control elements for the blocking member with those of the variable speed gear, to facilitate regulation by the crew.

Particular advantages are afforded by my improved burner arrangement in operating two main burners fed with pulverized pit coal. I 35 have found by tests that pulverizedpit coal can be burned satisfactorily only by adding a secondary supply of air. Then owing to the comparatively low quantity of conveying air, correspondingly small exit areas will be re-T quired on the burners which preferably are designed as so-called rose burners. Now it is myconcentric duct arrangement which in many respects constitutes the most favorable solution in designing these small burner plates. 5 Thus the burner surface exposed to the radia-' tion heat is-thereby reduced, this being aremarkable' advantage in respect'of the lfire box temperature of 1600 degrees centigrade, which is much higher than that prevailing in burning 1 pulverized brown coal. Furthermore, the efficiency of the burners can be regulated in a very simple manner within wide limits because of the fact that, as already mentioned, any desired quantity of pulverized fuel can be fed by adequately alteringthe rate of the conveyer movement evenwhen the one burner duct. is cut off from its fuel supply. In this arrangement thereforea'special auxiliary burner is not required at all;

1 of Fig. 3,

respectively, which are 'trunnion 'i terminates in a which may be mounteda lever s.

Moreover, my improved arrangement affords the advantage that the pulverized pit coal is very satisfactorily and quickly ignited when starting the engine, air being supplied only through the central burner, while dust-air mixture is blown in through the external, concentric burner. This good ignition is based upon the fact that by the addition of air through the central burner" portion, both the air con+ tact surface at disposal for the dust and the radiation surface acting on the escaping mixture, are increased. These conditions result'i-n.

the fact that pulverized pit coal, which is rather inert when compared with pulverized brown coal, may be ignited more quickly than hitherto. In order that my invention can be more readily understood, an embodiment-off-my" im proved burner arrangement is illustrated in the accompanying drawing. Fig. 1 is a central longitudinal section through the parts concerned of the plant. 7 Fig. 2 shows in a larger scale a detail in the same manner as in Fig. 1,

Fig. 2a is a sectional view along line2a-2a Fig 3 is a sectional view along line 33 of Fig. 2, and Fig. 4' is an end-elevation of the burner at the right of.Fig. 1.

In this drawing a denotes the pulverized coal containerfitted with a spiral conveyer 1)., adapted to convey the coal dust to a mixing chamber c. In this chamber, the air of combustion and the entraining air are fed through an air duct d which air with the dust streams through the burnerduct e'to .the burner f, Fig. 4, which is arrangedin the-fire box g of the locomotive, indicated by 'dot and dash lines. A second duct h is concentrically arranged in -the'duct e and i can be closed bya hollow breech piece pivotally. mounted on a pin 2, the open. position of this piece being indicated by a dot'and dash line' k The hollow breech piece k "is fitted upon its two sides with trunnions i and -1', pivoted in bearings n and r2 respectivelyin the-housing of the mixing chamber 0. The trunnion i is made hollow and communicates directly with the interior of the breech piece is. The trunnion i isprovided with four slotted openings u at its-periphery adjacentits;free end which are adapted to register with corresponding openings 22 in the bearing n. The slots 1), in turn, open into the circular channel-w, to which is connected an air pipe m. The square prism t upon In the positionof the lever s illustrated in Fig. 2; the breech piecek assumes the position illustrated in Fig. 1.- In-that'position the slotted openings u and v register with each other, and the air passing fromthe air pipe m through the circular channel w is admitted to the interior of the breech piece It and the duct h, which is shut off from the mixing chamber 0. Upon the shifting of the lever s in the position as indicated by dottedlinesin Fig. 2, the breech piece assumes the-position indicated atlc on Fig; l. The circular channel w is separated from the interior of breech piece is and the air from air pipe m can not'pas's into the interior of the breech piece.

At this timealso, the duct h is in communication-with the mixing chamber 0. Whenduct h is cut off from its fuel supply by the breech piece is, the 'remainingan'niflar surface P, Fig. 4, "of

. the burner 7 serves as an auxilary burner, while collar ment with gear 110 cooling air is admitted to the inoperative central burner portion from the air duct m through the hollow trunnion i, and through the hollow breech piece 7c and duct h. The variable speed gear in casing 11 is set so as to impart to the spiral conveyer b a suitably lower rate of revolution than that when the complete burner is operated: In the'position indicated in 'thd drawma axially shiftable clutchv coll'a'r y, engages loosely mounted gear .2, which transmits the motion from the drive shafts, upon which the is non-rotatably mounted, to counter shaft a, The motion imparted to the spiral cor'ivey'e'r" isr'e'duced by suitable gearing :c In the position for a higher rate of feed the clutch collar y is shifted directly into engageand thereby no speed reduction is effected upon the spiral conveyor. The control lever mechanisms for the breech piece is and the variable speed gear in casingn are interconnected as indicated by the connecting rods 0, p, q in such a manner that'when' duct h is cut off, the lower transmission stage is setfirst in the gear casing n and only then is the breech piece is swung to closing position. Conversely when full burner operation is.established', the duct his opened first and then the gears in casing n are set to impart to the conveyer b a higher'rate of revolution.

' Although my improved burner arrangement is thought to be used primarily with pulverized fuel furnaces on locomotives, it is to beundere stood-that it can be employed :with' thesame advantageous effect. in other type'sof boilers, such as marine boilers, stationary boiler plants,- etc. 1 1 What I claim is:.-

1. A pulverized fuel furnace comprising a burner subdivided into two concentrically .ar..-. ranged independent parts, two concentrically arranged fuel ducts each adapted to supplyffuel to one of said burner parts, a.fuel. container, a fuel conveying means adapted to feed fuel from said container to said two fuel ducts, means for cutting oif the supply of fuel to one of said two fuel ducts, means for adjustingthe feed of said fuel conveying means in accordance with the different demand of fuel causedby said cutting 01f, control means for saidcutting oif'means and control means for said adjusting means, and means for interconnecting said/two control means whereby upon cutting off the'sup'ply of fuelto'said'one of 'said'ducts, said cutting 01f control means operates subsequently to said feed adjusting control means, and'conversely; in the opening "of said one of said ducts to the supply of fuel, saidcutting' 01f control means acts prior 'to said feed adjusting control means.

2. A pulverized fuel furnace comprising a burner subdivided into two concentrically ar-' ranged independent parts, two concentrically arranged fuel'du'cts" each adapted'to supplyrfuel to'one of'saidburner parts, a fuel container, a spiral conveye'radapted to feed fuel from said container to said two fuel ducts, means -for driv 14 ing saidconveyer, a variable speed gear inter-' posed" between said 'conveye'r and -its driving means, control means for said gear, a pivotally arranged breech piece adapted to obturate one of said" two du'ctsf'means for controlling said 1:45 breech piece, means "for'so int'er c'onnectin'g'said' gear control means and breech piece control meansas' tocau'se said gear fto change over-to transmission of a low rate "of 're'voliitioii' "first an'd said breech piece to 'obt'urate said duet 150 thereafter, in the cutting off of the supply of fuel to one of said ducts, and conversely, upon the opening of the supply of fuel to said one of said ducts, to cause said breech piece to uncover said duct first and said gear to establish transmission of a higher rate of revolution thereafter, and means for supplying a cooling agent through said breech piece to said obturatable fuel duct when obturated.

3. A pulverized fuel furnace comprising a burner subdivided into two concentrically arranged independent parts, two concentrically arranged fuel ducts each adapted to supply fuel to one of said burner parts, a fuel container, a fuel conveying means adapted to feed fuel from said container to said two fuel ducts, a pivotally arranged breech piece adapted to obturate one of said two fuel ducts, a passage in said breech piece adapted to register by one end with said obturatable fuel duct when said breech piece is in obturating position, and a hollow pivot pin forming part of said pivot joint and adapted to be connected to a source of cooling agent and having connection with the other end of the passage in said breech piece when the latter is in obturating position.

4. A pulverized fuel furnace comprising a burner subdivided into two concentrically arranged independent parts, two concentrically arranged fuel ducts each adapted to supply fuel to one of saidburner parts, a fuel container, a fuel conveying means adapted to feed fuel from said container to said two fuel ducts, a pivotally arranged breech piece adapted to obturate one of said two fuel ducts, a passage in said breech piece adapted to register by one end with said obturatable fuel duct when said breech piece is in obturating position, a hollow pivot pin forming part of said pivot joint and adapted to be connected to a source of cooling agent and having connection with the other end of the passage in said breech piece when the latter is in obturating position, and means for adapting the yield of said conveying means to the different demand of fuel caused by said duct being obturated or not by said breech piece.

ERICH DIETZEL.

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