US1432317A - Apparatus for firing furnaces with powdered fuel - Google Patents

Description

j. 'J.,CBRAND; APPARATUS FOEFIRENG FURNACES WETH POWDERED FUEL. Lo

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y 1.1. C. BRAND.

APPARATUS FUR FIRING FURNACES WITH POWDERED FUEL.

TIASQQSIW .APPLICATION FILED MAR. 7. 1919.

Patnte Oct. IIT, T922..

5 SHEETS-SHEET 2.

J. 1. CI BRAND.

APPARATUS FOR FIRING FURNACES WITH POWDERED FUL.

- APPLICATION FILED MAA 7.19I9. L'l Patented @et 17, 1922.

5 SHEETS-SHEET 3.

1.1. C. BRAND.` APPARATUS FOR FIRING FURNACES Wl-TH POWDERED FUEL.

APPLICATION man MAR, 7, 1919.

1,43298171 Mmm oet. 117, 1922..

5 SHEES-SHEET 4.

1.1. C.. BRAND. APPARATUS FOR FIRING FURNCES WITH POWDERED FUEL.

APPLICTION FILED MAR.A 7,1939;

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Patented @cih il?, i922.

unirse stares rasant PATENT @FFHCE JAMES JOHN CANTY BRAND, OF SYDNEY, NEW SOUTH WALES, AUSTRAIA.

APPARATUS FOR FIRING FURNACES WITH 1PC)N'LDlllllRElID` FUEL.

Application led March 7, 1919. Serial No. 281,189.

To all wlwm it may concern.

Be it known that l, JAMES JOHN CANTLEY BRAND, subject of the King of Great Britain and Ireland, residing at Sydney, New' South Wales, Australia, have invented certain new and useful improvements in Apparatus for Firing Furnaces with Powdered Fuel, of which the'following is a specification.

This invention consists in apparatus for feeding boiler furnaces with powdered coal or coke. The fuel, which is ground to a very fine auge (in practice 85% passes through a g)I mesh screen and 95% through a 10() mesh screen),.is maintainedin a mobile condition by aeriication and is circulated through a continuous conduit to which it is supplied from a feed hopper, the required feed for each furnace being taken out of the flow circuit through separate gates and 20 control devices in the conduit and thence forced into the furnaces by a preheated air' blast which with'the circulation air provides the required volume of oxygen to eect combustion in the furnaces. rfhe particular apparatus used for'operating this system is hereinafter described with reference to the accompanying drawings, in which Figure l is a transverse sectional view through a vessel showing the firing apparatus as .applied to use on a` Scotch type boiler.

F ig. 2 is an enlarged fragmentary vertical sectional view through the boiler and a part of the fuel delivering apparatus.

Fig. 3 is a fragmentary horizontal secs tional view of the hot box and blast nozzle.

Fi 4 is a vertical sectional view through the fuel delivery pipe to the furnace, showing 'a fragment of the latter.

Fig. 5 is a fragmentary sectional view through the fuel conduit and conveying mechanism.

Fig. 6 is a top plan'view, partly in section, of the fuel feed circulating conduit', the air blast main and its connections. y,

Fig. 7 is an enlarged front elevation partly in section, of the apparatus, shown in Figure 6, and illustrating the apparatus 'applied to aY slightly different type of furnace from that disclosed in Figure l.

Fig. 8 is a frontpelevation partly in section of a modification of the apparatus.

Fig. 9 is a fragmentary front elevation, partly in section of a yfurther modification of the invention.

Throughout the drawings the same figures ofv reference indicate .identical or corresponding parts.

Referring to Fig. 1,` 20 is the hull of`a steamer, 21 and 22 wing bunkers therein, 23 and 24 boilers, and 25 the smoke stack. Each of the boilers contains three furnaces, but obviously the invention I:is applicable irrespectively of the number of furnaces or of the number or type of boilers inY an installation. 26 is an air preheater located in the base of the-smoke stack. lit is a heater of the tubular type through which air is forced by means of a fan or impeller 27, the heated current of air being driven thereby through the prehe`ater`26 into the air blast trunk 28, whence supplies of air are taken off to the separate furnace services. 29 is a closed hopper, and 30 a waste air shaft fromthe same leading up through the deck of the ship and in which a filter screen of the bag or other type maybe arranged. 31 is an air separator ofthe cyclone type, yhaving at the top of it a filter32; the lower end of this separator discharges into the hopper 29. Powdered fuel entrained in an air draft, and therefore in a perfectly mobile condition, is drawn from the storage bunkers 21- `and 22 by the centrifugal pump 33 through the pipe lines 34 and 35, and delivered through the pipe line 210 into the air separator 31. rll`he pipes 3a and 35 are brought into communication with tubular conveyers 36 located in the bottoms of the storage bunkers 21 and 22. Each conveyor 36 consists of a pipe of considerable diameter Set in the bottom of the bunker 22, having inlets at intervals into the bunker, which inlets are controlled by valves or shutters such as 37 which are manually operable from the stolre hold by a mechanical connection not 9.5 shown. A downtake pipe 38 is led into the pipe 36 to supply air thereto. rThis air may Abe atmospheric air drawn through the .bunkers as it is less liable to involve risk of igniting the fuel by oxidation. 58 are mechanical agitators each consisting of a shaft -with fingers or vanes or paddles thereon located in the store bunkers 21 and 22 and operating to maintain a free condition in the coal at the bottom of the bunker to facilitate its flow into the conveyers 42 through the valved apertures therein.

In Figs. 6 and 7 detail of the installation is shown. rlhe foot of the hopper 29 terminates in 'a sump 46 which is laterally offset from the continuous pipe conduit 47 carrying Va mechanical conveyor of any well known type. As shown in l* ig. 6, this conveyer consists of a continuous length of flexible steel wire rope 48 having attached to it at uniform intervals` push plates or discs 449l of substantially smaller diameter than the conduit. These plates or discs should have considerable freedom so as to minimize risk of choking if any packing of fuel should occur in any part of the circulating system. The drive is applied b `a jaw sprocket wheel 50 completely enclose in one return end of the conduit, and driven through worm wheel 5] by a worm 5,2X geared to the shaft 52. This shaft serves also to drive the screw feeders which take fuel from the. current circulating in the conduit 47 and deliver it to the several furnaces in the system. The detail of these feeders is shown in Figs. 2 and 5. 53 -are the furnace feed pipes, 54 pockets which take fuel by gravity from -the conduit 47 into the screw feeders which move it at a uniform rate into the pipes 53. The furnace doors 57 are constructed and hung so that they may be opened when required to permit access to thefurnaces Without disturbing the furnace `feed pipes The. capacity of the conduit conveyer is such that it will always deliver fuel at a rate in excess of the maximum demand of the several furnace feeders served by it, so that some surplus is always carried round the circuit. At appropriate intervals in the conduit pipe 47 a system of grated ports or vents 60 in the bottom thereof open into the pockets 54 (Fig. 5) which form receivers for the furnace feeders' working in the barrels 63. These ports are opened more or less as required by slide valves 61 which are controlled by hand grips 62 extended through the sides ofthe pockets 54. ln these barrels, screw feeders 64 y operate to move the fuel received through the pockets 54 into the furnace pipes 53. Above the junction of each. barrel 63 and the pipe 53 a straight extension air pipe. 65 is connected into the air trunk 28, a valve 66 of buttery maintain a mobile condition of the fuel in which the feed screw is working; this air passes also up into the conduit 47 Ithrough the ports or vents 60 the-rein, `and thus assists to maintain a mobile condition of the fuel in circuit in the conduit. As the fuel is maintained in semi-suspension inthe air passing through the various pipes and other parts of the apparatus it does not tend to deposit or pack in any part of the Vsystem to an extent which would cause operating difficulties. The spindle of the feed screw 64 is extended through the back end of the tube 63 and carries a friction disc 67 on a feathered sleeve 68. A helical spring 69 in compression oper-ates normally to push/th@ friction disc 67 against the edge of the drive friction disc 70 which is keyed or pinned to the shaft 52. A control handle '71 forkconnevcted to a grooved sleeve on the rear side of the disc 67 provides a means whereby the disc 67 may be retired from contact with the driving disc 70 when it is required to put any partlcular furnace feeder out of operation. The rotational rate of the screw 64 is determined by the set of the drive disc 70 on the spindle 52, a faster rate being obtained by moving that dise nearer the centre of disc 67, and vice versa., butterfly or gate valve in the pipe 55 for controlling the air supply from the air trunk 28 therethrough' into the inlet end of the feeder barrel 63.

It is desirable to extend the fire door end. of the furnace flue forwardly a greater or less distance for the purpose of shielding the flue plates 0f the boiler from injuriousl excessive temperature. 'lhe fire doors 57 are mounted in the extension end plate 76, and behind said plate an air chamber 77 is contained forwardly of the fire brick diaphragm 78. The burner nozzle 79 is outwardly splayed and fitted internally with a mouth cone 80 which operates to spread the blast as a conical annulus. lt is water jacketed as shown at 81 and fitted with a tubular 'collar 82 having vents 83 cut around it placing the annular air collar 85 in communication with the chamber 77. The chamber 77 ported as indicated at 84, is connected through a pipe 95, (Fig. 1), with the air blast pipe 28. The collar vents 83 are formed tangentially, as best seen -in.: Fig. 3, for the purpose of applying a whirling motion t0 air passing from the chamber 77 through them into the collar space 85 which surrounds the annular mouth'86 of 72isa" the nozzle. The nozzle is withdrawable without disturbing its relation to the conical collar` 482 when the fire doors 57 are opened. To facilitate its withdrawal it is mounted on the end of the furnace feed pipe 53 by a slip joint 87. In the end of the furnace feed pipe a helical vane 88 is fitted to deflect the blast passing into the burner nozzle thereby .to whirl the blast ,of fuel as it entersr the furnace. The direction of rotation of the fuel blast and ofthe collar air blast correspond. Within the furnace flue 90 directly in front of the nozzle, a checker work fire brick hot box 91 is copstructed. .Initial combustion takes place in this boX, which becomes incandescent, and the flaming gases therefrom pass through the checker vents into the boiler flue 90 and thence through the tube system of the boiler, finally passing out as usual up through the smoke box 92 to the uptake 25. 93 and' 94 are the rinlet and outlet water connections to the water jacket 81. They are connectedby flexible pipes to cooling'water service and eduction pipes. In Fig. 1, portions of the air pressure connections into the chamber 77 are marked 95 and they are valved so that the blast through the collar lnozzle 85 is immediately controllable.

According to the option of the designer 'the type of conveyer used in the continuous conduit 47 may be varied. Thus, for instance, a chain conveyor with offset claws on its links carrying Scrapers may be used. The invention is not concerned with the'particular structure of the conveyer used so long as it functions to maintain movement of air borne fuel through the circuit without causing packing of the fuel and consequent choking. A modified type of conve er is shown in the arrangement in Fig. 8. n this case the fuel is drawn from the bottom of the 'hopper 29 by a long screw conveyer 97 which moves the fuel through the straight line conduit 98, said conduit being fitted with pockets and valves similar to those shown in Fig. 5, one for each furnace feeder as shown at 54. The surplus overcarried -fuel passes into the end sumpy pipe 100 whence it is educted pneumatically and returned through the pipe 101 and the cyclone air se arator 31 to the top of the hopper 29. neumatic conveyer action is effected by means of a centrifugal pump 102- which maintains circulation through the pipe 101 from the sump 100 to the air separator 32. To aid the pump 102. an air pressure injector is fitted in a junction 103 at the lower part of the pipe 101, and a blast air service thereto is provided through a pipe 212. Mobility of the fuel in the screw conduit 98 is ensured by carrying pressure air pipes 104 into said conduit above each of the fuel controlling valves 61. These pipes 104 take the place of the pipes 55, and

the gate discharges directly into the furnace pipe 53, the feed screw 64 used in the other type 0f furnace feeder being omitted. The

quantity of the feed served to each'furnace is determined by adjustment of the shutter valves identical to the one indicated at 61 in Fig. 5. Where one feed service is connectedto a pair of furnaces as shown in the two lower furnaces in F ig. 8 aturnover valve 106 is fitted. The casing of this valve is ported to deliver feed to either or to both furnaces. {The air blast pipes 104 are connected through appropriate valves to the air main 107; this air main corresponds with they air main 28 shown in. Fig. l. 108 is an air main connected by branch pipes 109 to t-he air boxes 77 (see F ig. 3) which enclose the blast nozzles. main 107 may be omitted .if the pipe connections 104 are led. directly from the main 108. This is in effect what is shown in Fig. 9. Tn a further modification Fig, 9 the fuel withdrawing arrangement from the bunker 21 consists of a conveyor 42 fitted with a continuously `rotating shaft armed with screw vanes 43 which move the coal towards the sump 45". Powdered coal is in this case, together with the air in which it is suspended, delivered into the air separator 31 from which it falls by gravity into either of two flasks 202--203, according to the set of the gate 204 in the breeches pipe 105. The lower ends of the breeches pipe are fitted with valves 206-207 which are movable by means of a screwed spindle 208 which is readily turned by means of a hand chain 209 or otherwise. oot valves in the -chambers 202-203 are cross connected by a link 110 which may be interlocked by any convenient mechanism with the valve 204, so that one of the chambers 202-203 lis discharging while the other is filling. An air pipe 111 supplies air through a valve branch connection 112 to the top ends of the chambers 202-f203, with the object of providing top pressure on the fuel in said chambers to force it by direct pressure behind it through the service conduit 113, whence it is drawn off direct through valves 114 into the furnace feed pipes 53, the upper ends of which are valved and connected into the air blast main 28.

The blast nozzle shown in Figs. 2 and 3 has been proved to be an effective instrument for introducing the aerified dust fuel into the furnace in a way which ensures adequate control of air supply and effective combustion, but it is obvious that the fuel supply through the system to the furnace feed pipes 53 may be introduced into the furnace bymeans of nozzles of known construction not corresponding structurally with the nozzle shown in Figs. 2 and 3, and that the baflie checker work within the fore end of the furnace flue may be structurally varied to intercept the blast and localize the Vcombustion and establish a zoneof 'intense to a plurality of furnaces comprising powdered fuel bunkers, a valved pipe in each bunker, means for supplying airl to said pipe, a delivery pipey leading from each bunker, means for withdrawing aeriiied fuel through said delivery pipes, a feed hopper supplied by said `withdrawing means, an endless fuel and air conduit communicating with said feed hopper and provided with valve controlled openings, a barrel fed from each valved opening, a furnace feed pipe supplied by each barrel, a powdered fuel burner on each furnace feed pipe adapted to be located in each furnace,a`n air preheater, an air` pump, a hot air main communicating with said furnace feed pipe, and a valved pipe leading from said air main `to each barrel. l

2. Apparatus for feeding powdered fuel to a pluralityof furnaces simultaneously or in order as required comprising powdered fuel bunkers, a valved pipein each bunker, downtake pipes to supply air thereto, mechanical means for agitating the coal in the vicinity of each valved pipe, a delivery pipe leading from each valved pipe, an a1r separator, a small capacity hopper communicating with the delivery pipe throughthe air separator, an endless fuel circulation conduit communicating with the hopper, suction means comprising a pump for drawing aerified powdered fuel from the lower part of the bunkers, through said delivery pipe and forcing it through said air separator and said small capacity hopper and thence into the endless conduit., and means for feeding the fuel from said conduit into individual furnaces.

3. 1n apparatus for feeding a plurality of furnaces, a powdered fuel bunker, means for withdrawing fuel from said bunker, an endless fuel conduit fed by said fuel withdrawing means, the bottom of said conduit carrying a valved control opening therein for each furnace to be fired, a mechanical feeder associated'with each valved opening, a furnace feed pipe leading from the outlet end. of each mechanical feeder, a powdered fuel burner communicating with each feed pipe, means for driving each mechanical feeder independently, a hot air pressure main to supply air to each mechanical feeder, and valved pipe connections establishing communication between said hot air main and the inlet and the outlet ends of each mechanical feeder.

4. Apparatus for feeding powdered fuel to a plurality` of furnaces simultaneously or in order as required, comprising fuel bunkers, a valved pipe in each bunker, downtake pipes tojsupply air to said valved pipes, means for agitating the fuel in the bottom of each bunker, a high level hopper, pneumatic means for delivering fuel from each bunker to said hopper, an `endless fuel conduitfed by saidhopper, a conveyor in said conduit, said conduit having valved control openings therein, mechanical feeders associated with said valved openings, a hot air main, pipes establishing communication between said'mechanical feeders and said hot air main, a furnace feed pipe leading from each mechanical feeder, and a burner nozzle on each furnace feed pipe adapted to be located in the inlet end of each boiler furnace. l

5. ln apparatus for feeding powdered fuel to a plurality of furnaces simultaneously or'in order as required, powdered fuel 4means, a high level hopper communicating with said air separator, and fuel delivering means associated with said hopper.

6. Apparatus for feeding powdered fuel 'to a plurality of furnaces slmultaneously or in order as required including powdered fuel bunkers, a valved pipe in each bunker, means for aerating fuel in each valved pi e fuel conducting means connected with t e valved pipes, an endless conduit fed by said connecting means through which aerified fuel is maintained in circulation, controllable valved openings in said conduit, mechanical feeders each supplied by one of said valved openings, a hot-air blast main, a valved pipe from the hot air blast main into the inlet of each mechanical feeder, a valved furnace feed pi e from said hot air main connected with t e delivery end of each mechanical feeder, and a water jacketed burner nozzle on the delivery end of each furnace feed pipe.

7. lin apparatus for feeding a plurality of furnaces, powdered fuel bunkers, a valved pipe in each bunker, pipe lines and pneumatic means for withdrawing fuel therethrough from said bunkers, a high level hopper fed by said pneumatic means, an endless conduit communicating with said hopper, a valve controlled opening in the bottom ofthe conduit for each furnace to be esv inlet and the outlet ends of each mechanical l0 feeder.

y l[n testimony whereof l have affixed my signature hereto.

JAMEs JoHN ciiNrLEY BRAND.

llVitnesses:

W. Gf. HUPHREYS, H. C. CAMPBELL.

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