US2115407A - Construction of locomotive boilers, etc. - Google Patents

Description

April 26, 1938. H. BLUNT CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

8 Sheefs-Sheet 1 Filed April 15, 1951 April 26, 1938. E. H. BLUNT CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

INVENTOR .Blz mt. EY/fi ts-Sheet 2 TTORN lllll ITI Filed April l5, l9

April 26, 1938. E. H. BLUNT 7 CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

8 Sheets-Sheet 5 NVENTOR Filed April 13, 1951 April 26, 1938. E. H. BLUNT CONSTRUCTION OF LOCOMOTIVE} BOILERS, ETC

5% \m3 mum;

April 26, 1938.-

E. H. BLUNT CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

Filed April 15, 1931 8 Sheets-Sheet 5 ATTORNEY April 26, 1938. E. H. BLUNT CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

8 Sheets-Sheet 6 INVENTOR Edmund ATTORNEY 3 Filed April 15, 1931 IIKI o b N9 mw April 26, 1938. E. H. BLUNT CONSTRUCTION OF LOCOAGOTIVE BOILERS, ETC

Filed April 13, 1931 8 Sheets-Sheet 7 April 26, 1 938. E BLUNT 2,115,407

CONSTRUCTION OF LOCOMOTIVE BOILERS, ETC

Filed April 13, 1931 8 Sheets-Sheet 8 //vl/EN Tole ia/wu/vo h. .61. 0N T R W ZZ r7 TO/FNEY Patented Apr. 26, 1938 UNITED STATES PATENT OFFHCE Edmund H. Blunt, Brooklyn, N. Y.

Application April 13, 1931, Serial No. 529,728

7 Claims.

One object of my'invention is the reliable supplying of sufiicient amounts of highly heated air to the boiler to properly promote combustion therein.

Another object of my invention is to provide adequate and effective means for the use of powdered or finely crushed fuel in a locomotive fire box.

In one arrangement of my invention the air enters a duct adjacent the smoke stack and passes first through a chamber where it is moderately heated by waste steam. From this first heater, the air is drawn into a second chamber where it is heated by hot gases from the fire box. The highly heated air then passes into the fire box. Part of the hot air may be used to carry the fuel along with it into the fire box.

In applying this arrangement to a modern type locomotive a number of improvements have 20 been developed, 1. e.

1. Details of means for the practical supply of pre-heated air to the boiler furnace.

2. Adjustable means to pass such pre-heated air through the boiler independently of the main engine exhaust.

3. Means employing pressure developed by the moving engine to force incoming air through the heater.

4. A fan or blower drawing air from the first stage air heater and forcing said heated air through the second stage heater, and to the boiler.

5. Details of a first stage air heater using surplus steam to warm the contained air.

6. Details of a second stage air heater using hot fire box gases to heat the contained air.

'7. A thimble through the inner and outer walls of the boiler water-legs to permit the passage of certain amounts of fire box gases to without the furnace or fire box limits.

8. A secondary smoke stack into which the required fire box gases may pass.

9. A damper in the passage to the secondary stack that automatically tends to close whenever the escaping gas temperature rises above a determined point, and vice versa.

10. A maximum sized combustion chamber to promote the complete burning of fuel.

11. A three pass, reverse flow, furnace whose main passes are substantially horizontal and parallel.

12. A combustion chamber wherein fuel is admitted to the upper pass and successively progresses downward.

13. A combustion chamber with walls protected by water-screen tubing of a flattened or oval type.

14. A hot air passage to the pulverized coal supply to assist its delivery to the boiler.

15. A transparent hinged wing to widen the bell mouth opening into the first heater.

16. An emergency oil burner near the coal burner that will maintain a small fire and so reduce standby losses of fuel.

These features and others singly and in com bination, constitute marked improvements in the construction of the modern locomotive, all tending to increase its economy and effectiveness.

Whereas the pre-heating of the air of combustion by the waste heat of the escaping gases through the stack is a recognized economy in stationary plant practice, the space restrictions on a locomotive would seem to prevent its practical application on the latter, especially were the general form and dimensions kept the same.

In fact, the prevailing forms of plates and heating surfaces as used by the former .are proportionately so great that it is impossible to find spare room within the locomotive clearance limits. Also the distance from the source of heat, the smoke stack to the fire box in the rear adds to the diificulty of providing a conduit of sufiicient cross sectional area to carry the heated air along the whole length of the boiler body andto its delivery to the fire box.

I propose overcoming this difficulty by using some of the waste heat of the escaping steam instead, conveying the latter by means of a pipe leading from any exhaust steam passage to an air pre-heater to be described. The problem therefore requires the providing of a suitable preheater, a place to install it and means for expeditiously conveying the resulting heated air through the fire box of the locomotive.

The locomotive exhaust steam under norma back pressure from the enginemight approximate a temperature of 225 degrees Fahr. As the heat transference through metal surfaces is proportional to the difference in temperature between this steam and the air to be heated, it is obvious that the resulting air temperature will be less than that of the steam depending on the amount of air to be heated.

Owing to the great amount of air required and the limited space in which to install this first stage heater, the temperature may not be high enough for a proper combustion, so I propose taking this partly heated air and passing it through a second stage heater, thereby supplying extremely hot air to the boiler fire box or furnace.

, a forced draft system with a closedfire box, giving ing readily applied to those already built. The

a more perfect control of the varying percentages of air. needed by the burning'coal. V 7

By introducing a fan or blower after, the first stage-heater and before the second stage heater,

a further improvement is accomplished, asthe first, heater has the incoming cool air drawn through it delivering this moderatelyheated air to 'the fan whichis thereby not overheated. This hot air'is then forced into the second heater which is constructed so that it is not affected mechanically by the previously heated air or by its overheat. r

' This arrangementnotonly keeps the fan ata reasonable temperature and in excellent operating condition, butpermits itsinstallation alongside of the boiler, accessible but sheltered. Contrariwise,

it would be diifibult to properly mount-a fan that would first force the cold air into the first heater and then into the second'one, should my above mentioned system of Indu-force or inducedforced draft be omitted.

.On the drawings, Sheet 1, is shown a simpleair heater assembly :as established on an existing type of a. large sizedmodern American locomotive, increasingly coming f intouse, This suggested adaptation of my air-heater is comparas tively inexpensive and 7 involves no appreciable change in the construction of the'locomotive, be-

heated airmay be applied toany type of furnace to promote efficient combustion, but'preferably to one with a closed fire box.

On Sheet 2 is shown the same tivebut with the smoke box,'or front end extended forward to allow greater room for a saddle-type of air heater mounted directlylbehin'd the smoke stack. To provide for a maximum capacity fire box that will the more efficiently burn fluid or flowing fuel, such'. as powdered or pulverized 'coal or oil; I prefer transferring the auxiliary tractor or booster from the rear trailing 'axle to the tender'axle thus permitting an appreciable lowering of the fire box and ash-pan as shown. This change only calls for a new water-leg fire box supported on a new type trailing truck,'the

general proportions of the locomotive remaining unaltered. :This may be readily seen on Sheet '6. H To provide forthe greatest lengthof travel for the fuel and also to keep. it in suspensionthe longest time before reaching the fire tubes I have designed athree-pass fire box as shown'on Sheet 6. j r a -Owing to-theintense heat. generated in the third or bottom pass and'the necessity of .absorbing enough of it to reduce the temperature and so prevent the fusing of the enclosing firebrick Ihave devised 'a pipe ,water-screen of parallel fiat or oval sections that may lie closely together and also properly fastened into common supply headers. YThese are in detachable sections or units and are freely interconnected to take care of the large expansions due to temperature changes that may occur. 7

Another important feature is the use of a secondary smoke stackf, preferably located at orv near the rear. of the boiler, as shown. 'This'and type "or locomoomitted, also showing the coal and air piping an automatically controlled damper will be duly first stage heater by means of a bell-mouthed opening and an outswinging fshutter that will not appreciably interfere with the forward vision of the engine crew.

' described. Advantage is also taken of the rapid forward motion of the, locomotive to assist in a driving the cool air into the forward end of the In some instances it may be advantageous to heat'the'first stage air heater. to amoderate temperature by the use of smoke stack gases, and then deliver the air to the second stage heater, butthe V steam heated means is the preferred way. In the description of my present invention the following figures are shown:

type locomotive with my invention applied.

a 15 Fig. 1' is a left side elevation of a standard] Fig. 21s a front elevation on the line 22 of V Fig-.1.

Fig. 3 is a section on the line 3-3 of Fig 1.-

showing the bell mouth andshutter.

Fig. 4 is'a side elevation of Fig.8 showingthe bell mouth of the heater and the attached shutter.

Fig. 5 is a top View of'the bell mouth on the V .25 1 Fig. 6 is a section of the fire" box water-leg'on line 55 of Fig. 3. i

the line 66 of Fig. 1. r

Fig. 7 is a side elevation of a modification ofthe 1" construction shown in Fig. 1.

Fig. 8 is a topplan of Fig. Twith the roof of. at

removed,-arrows showing the flow of heated 3411:1130

the fire box, etc. 1 1 Fig.9 is an enlarged sideele'vation of the forwardhalf-of thelocomotive of Fig. 7. 4 i

Fig. 10 is ahalf top plan of Fig. 9with parts of the. air heater broken away to show interior! Fig..11 is'a front elevation of the construction of Fig. 9 comparing the first stage heater casing:

with the cab outline.

Fig. '12 is a part section onthe line' l2 l 2 of Fig. 9. a g i Fig. 1315 a part. section onthe line 43M Fig. 9 showing the turbine-blowerand air inlet. a

'Fig, 14 is a part section 'ontheline 14+! of Fig. 9 with transition piece to the second 'stage4 heater.. Fig. 15 is a part section through :the rear portion of the first stage heater on the line"l-5l5 ofFig.10. Fig. 16 is. a part section through the front'pore units. I I

Fig. 17 Ba side view of the nesting headers for curved heating tubes, ,on'line l'i-JlofFig. 15.

tion of the same heater'onthe line l6l6 of- Fig. 10, showing groupings of 3-plate heating;

Fig. 18 is an enlarged detail of the header nesting ofFig.15f V Fig; 19 is a section online l9l9 of Fig. 18

- showing groups of fins mounted on the curved heating tubes.

of heating unit that maybe used in Fig.16.

Fig. 21 is an enlarged side elevation of the rear part of the locomotive of Fig.7 and is a continuation of Fig. 9 and shows the assembly of the sece; ond stage heater.

. r 7 to f Fig. 20 is an enlarged plan of afive-plate type Fig. 22 is a part top plan'of Fig-Z1 with the. cab

the tender.

end on the line 23-23 0f Fig. 21.

Fig. 23 is a left-half section-of the boiler rear Fig. 24' is a vertical section through the center of the boiler fire box on the line 24-24 of Fig.

22 showingthe coal burner, and supports, etc.

three-pass furnace V V Fig. 25 is a left-half section of the boiler on the line 2525 of Fig. 24.

Fig. 26 is a right-half section of the boiler on the line 2626 of Fig. 24.

Fig. 27 is a right-half plan of the ash-pan and truck frame on the line 2'l2'| of Fig. 24.

Fig. 28 is a portion of a plan on the line 28-28 of Fig. 24 showing the burner and air-supply.

Fig. 29 is a vertical mid section of the boiler similar to Fig. 24 and showing water-screen piping to protect parts of the ash pan.

Fig. 30 is a plan of the piping on the line 30-30 of Fig. 29.

Fig. 31 is a left-half section on the line 3|3l of Fig. 29.

Fig. 32 is a right-half section on line 32-32 of Fig. 29.

Fig. 33 is a detail plan showing means of attaching flattened water-tubes to their headers.

Fig. 34 is a sectional view and side elevation of the parts shown in Fig. 33.

Fig. 35 is a front elevation of the pipes and adjacent headers on the line 35-35 of Fig. 33.

Fig. 36 is an elevation and section on the line 3635 of Fig. 35 showing inside bolt connection.

Fig. 37 is a sectional plan through water piping connections to an outside water header shown on line 31-31 on Fig. 29.

Fig. 38 is a sectional elevation of the secondstage air heater but in two divisions controlled by several air dampers to give a varied control of the heated air.

Fig. 39 is a side elevation of a second stage air pre-heater showing an additional hot gas discharge regulation.

is the locomotive boiler shell, 2 is an existing type of smoke stack, 3 is a proposed type of a primary smoke stack, 4 a secondary smoke stack, 5 the running board, 6 the main steam cylinder, 1 the driving wheels, 8 a typical 4- wheeled trailing truck, 9 a proposed 4-wheel trailing truck, H! the rear tube sheet, ll the fire box crown sheet, 12 the side water legs of the fire box, It the rear water leg or back end of the boiler, M the combustion chamber, l5 location of prevailing type of fire grate with attached ash pan, Hi the cab, l'l-the cab floor, IS a front window of the cab, 59 the engine-frame, and 20 and 2| the front and rear trailing axles, respectively, of said trailing trucks.

The mud ring is 22, while 23 is the coupling, 24 the tender and 25 a proposed ash-pan casing.

It appears preferable to install the air-heating apparatus in duplicate, for instance, on both sides of the boiler center line which I have marked C/L, this symbol also denoting other center lines about which other parts may be symmetrical. Generally speaking, the same reference number applies to both sides of the locomotive.

It will be noted, however that occasionally and where part-sections occur, that a right side apparatus may appear along with a left side companion installation.

On these occasions I may add a letter R to the number to signify the right hand member, or an L to mean on the left hand. Thus I2L is the left hand water leg while |2R is the corresponding right hand water leg.

In Fig. 1 the incoming cold air enters the forward end of the first stage heater 26, which in Fig. '7 is divided into a forward portion, 26A and a rear portion 23B. It is there partly heated by steam means and passes out and downward through air duct 2! to a fan or blower 28, preferably of the steam-turbine driven type, and here shown installed below the running board 5. Fan 28 is operated by the throttle controlled live steam conduit 21a.

In Fig. 1, fan 28 delivers the air to a circular duct 29, and through a transition piece 30, and to a rectangular casing 31. that is an enclosure for the secondary heating operation and known as the second stage heater. In Fig. 6 hot gas from the combustion chamber l4 passes out through the water leg thimble 33, hot air conduit 34 tothe hollow heating conduits 35 within the heater casing 3i, still further warming the air delivered to this heater by fan 28. A certain amount of hot gas-flow within the conduits 35 is necessary to promote an exchange of heat.

This may be accomplished by discharging the cooled gases through an external control valve or damper 35, to the atmosphere or otherwise.

The air of combustion heated to its highesttemperature passes through the heater end 31 into conduit 38 to the fire box or where ever else required. Its use in this manner is an economy when ever applied to any type of furnace or used with any kind of fuel.

To avoid unnecessary duplication, the front end of heater 26 is shown with its bell-mouth features omitted in Figs. 1, 2, 7, 9, and 10. On Figs. 3, 4, 5, and 8 the bell-mouth 40 is shown, also a transparent shutter or wing 4i hinged to it.

This shutter is normally kept open, as shown,

by a spring 42 forcing the shutter against an adjustable stop 43 that regulates the outward spread of said shutter. Passage along the running board 5 may be made by pushing shutter 4! to the dotted position 44 of Fig. 5.

Fig. 3 also shows a dotted outline of the cab I E and the outlook window E8. The shutter 4| is designed to permit a view of the track through this window and also to allow a proper view of any overhead signals that the train may be approaching. 1

Fig. 7 has been separated on a line through the fourth driving wheel marked 45, into a larger scale forward portion as shown on Fig. 9 and a rearward portion as shown on Fig. 21. d

Fig. 10 shows the two diiferent air-heating systems that may be installed on top of the boiler. Attention is here drawn to a 'heater design providing the greatest capacity steam air-heater on top of the boiler barrel while at the same time allowing forward vision from the cab windows such as is shown in the front end view of Fig. 11.

There are at present two different systems of air heating, and certain operating conditions seem to govern the choice of which may be the preferable. One system depends on smooth, hollow plates to transmit the heat, while the other system consists of small-diameter parallel tubing on which are assembled closely placed plates, very thin, and whose planes are at right angles to the axis of each tube. Believing that the use of both these systems is valuable in operating my first stag-e heater I have assembled the smoothplate system in the forward portion, 26A. while using the fin-tube principle in the rear section, 26B of said heater.

A partial cross section of the plate-system is shown in Fig. 16 and the fin-tube in Fig. 15, both to be described later.

A turbo-driven fan such as shown at 28 may be mounted on one side of the locomotive only, though it appears preferable to employ two smaller fans or blowers, one on each side to give flexibility to the varied power demands.

In Figs. 7 and 21, 46 is a second-stage air heater ofsdiflerentsinternal construction from heater 3! of 1. 'Air from transition piece 30, but partially heated, is forced through it,

becominghighly'heated by later described means. and driven through the rear portion 4! and into transverse duct 48 that may connect with a similar ductr 47R connecting with a similar heater 7 V on the right side of the locomotive.

vAn air outlet 49"from duct, is joined by flexible or articulated conduit; 50 to pipes 5IR and SIL, the latter being connected to the left fuelhandling system 52L, i I

Prepared fuel from the tender 24 may enter SZLand be conveyed forward by the worm 53 into an air-lock such as 54.

lowerchamber (not shown) into which 5IL is also'forcing heated air; This air lock is designed to prevent the air from backing up into 52L. A chain orbelt '56 may be used-to keep the paddles 55 in step with the worm 53. 7

Coal-is forced by the heated air '(or by "other suitable means) into duct 51, flexible pipe 58,

' connecting pipe 59 and pipe :60 thatenters the backhead I3 of the boiler. A swivelor universal joint 6| permits adjustment ofthe fuel discharge to'difierent portions of the firing chamber 'or pass I0. A sufficientlylarge thimble through I3, such as 62 (similarto 64 of Fig. .24) permits this.'

To pipe, 60, is attached an accepted typeof coal-burner such as'65 (see Fig. 24), that can be moved or rotated by said pipe. Several of these burners may be installed and the amount of fuel consumed may be regulated by changing the speed of 'the Worms 53,'by damper adjustment ,(not shown) by change of fan speed and amount of air supplied, singly or in combination. 'The burner 65 distributes the incoming coal, well dif fused andfmixedwith'the proper amount of hot air, and ready to ignite in the shortest interval of time.

; 'The fuel and air enter theupper pass I0 and are deflected by the baflle wall II 'into the second Then backward,downward and forward a through thethird pass'l3; assisted by the baflles "I4 and 15, all shown in Fig. 24..

The hot gases thenipass'to the rear tube-sheet I0, through the fiues and fire tubesIB, heating the water withinthe boiler, and thence out the smoke stack 3 to the atmosphere. 7

Heat is supplied to the second stage heater 40 by hot fire box gases that. may pass through the waiterlegs I2, by means of thimble openings I9,

7 into connecting conduits 80, andto' hollow heating elements 8| contained withinthe heater casing 46.

' The gas contents of 8| are discharge d into an vmo-cou'ple 84 having: wiring 85, whiclimay be inserted into the gas stream, and the variations of heat within the passage 82 will electrically affect a control box such as connected to a 7 primary or storage battery 81 and a? solenoid 88. v

. The control 80 is adjusted to function whenever 'ie heat impinging on 84 rises'above a pre -determined temperature. rBoxr 86 allows a current to pass from01 to 88 to operate valve 89, ad-

This air lock may use revolving paddles 55 thatjadmit coal to a arched brick I I I readily removed.

mitting] steam or air to cylinder l90. 'Also'the solenoid may directly operate damper B3. Piston '9I within a cylinder 90 will cause damper 83 to rotate thereby controlling the hot gas discharge into stack '4.

'VTomake this discharge more effective I. pro- ,pose introducing a steam jet 92 into the secondary stack 4, as an additional draft control. A valve 93 is in the pipeline 94' leading from some steam supply, such asthe steam discharge of the fan turbine 28. r

' The force of this'jet should increase as the air flow through the heater becomes greater,.asja

greater amount. of heat has to betransmitted to this air, and necessitates a greater flow of hot gases through the heating elements and out through the secondary. stack to the atmosphere.

As this air fiow is proportional to the steam that drives the turbine; the increase of exhaust steam discharged to the jet tends to stimulate the hot gas flow just when it is most'needed. The heated air within heater 46 hasalready mately to the coal burner 05. V

I maydivert Varying amounts of this air from the heater such as from another outlet 95 and been described as passing to the tender and ultiinto a conduit 96,-to and above the top, and towards the center of the boiler, then entering the cab, passing down through conduit 91 (Figs. 23, 24, 28) through thimble 64, into duct 98, within upper pass I0, and to burner 65 in a well-known manner. Various dampers such as 99 may be emin this manner.

Duct 98.may connect with a fire brick passage such as I00 controlled by valve IOI discharging .through' various openings such' as I02, so as to ployed to regulate the amounts of air supplied conduct additional air to diiferent parts of the firebox as may be required to maintain perfect combustion.

Ignition-boiler pass I0, reverse-pass I2, and ash-pan pass I3 are separated by firebrick arches the most I03 and 'I04'carried on arch tubes I05 and I035 respectively; Firebrick'wall I0! is used to separate the igniting gases from the cooler metal walls of the boiler, and to maintain an incandescence at other times to reheat the fuel when again startingup the burners. r

Water enters arch tube I05 from the rear head I3 and discharges forward into the boiler as shown. I may providea more flexible connection a such as shown in the lower level, wherein water from a vertical riser I 08 supplies a, header I09 1 carried at one end by'riser I08 While the other end' is supported in a pocket I I0 recessed into the water-leg as shown in Fig. 32. The lower arch tubes I06 are supplied'byheader I09.-

Arch tubes I05 and I06 convey the water forward to the boiler, having sufficient flexibility to take care of excessive temperature variations. These tubes are spaced apart to'clear each other at passing points;

and repairs, this space being covered by the A wider spacing of these tubes occurs at the center to allowroom for entrance To prevent the rapidly travelling fuel from accumulating on the floor of each pass, I propose installing variously placed and inclined deflectors or. hurdles II2 to direct the'moving coal into the gas stream. above.

Firebrick baffle TI, Fig.24, may be held in position by a water protected hollow member such as at II3 attached to thecrown sheet II.

Figs. 29 to 37 show a system of water screen.

protection of the sides and bottom of the ashpan and lower parts of the combustion chamber.

To supply these water screens at their lower ends I propose withdrawing water from the cooler part of the boiler such as the bottom of the shell at I25 on Fig. 24, into pipe I2! having an emergency stop or control valve I22. This pipe I2I enters the forward end of the ash pan, as at I23, which should be supplied with suitable air tight means of closure.

In these drawings there isa symmetrical right and left layout, though duplicate parts have often been omitted to avoid confusion of detail. To obtain the proper protection of the refractory lining such as I24, the pipe screen should be in close contact with said lining.

Interior supply pipe I25 connecting with I23, is shown bent. Through the nozzles such as I26, it discharges into the inlets I21, of bottom header I28, to which are attached pipe risers I29 and These risersenter a top header I30. Water leaves header I35 through bent pipe I3I, passing out through water leg thimble I32 and discharging into outside header I33 to which I3I is detachably connected, as by a special hollow-headed nut I34. I

Header I33 may supply the pipe I35, discharging into the back head I3 of the boiler but controlled by a non-return valve I36. Another header I31 likewise feeds into a valve-controlled pipe I 38, entering the boilerbarrel at a point not shown.

These outside headers are free of the boiler so as to allow for expansion adjustment. Likewise the pipes I3I have clearance within the thimble I32, the latter being closed by removable split plates I39'that stop the escape of furnace gases from or the entrance of cold air to the fire box.

Bottom header I28, Figs. 33 to 36, has the inlet I21 in tight contact with the outlet nozzle I26 of pipe I25, as detailed in Fig. 36. To maintain this contact, bolt I threads into a spider I46 protected by the water within pipe I25, only the bolt head it? being exposed to the flame, said bolt head being hollow and filled with water from In Fig. 31 curved pipe I3 I passes through split plate I39 that bears against thimble I32. A boss or bearing piece I48 on this pipe is held against outside header I33 by the hollow headed nut I34 having a bearing flange M9. This nut is internally threaded and engages an outside thread on the pipe ISI. An external opening 150 in the opposite wall of I33 and closed by a plug or otherwise, provides access for turning :the hollow nut.

Water screen tubes I23 are preferably of oval rather than circular section, similar to I55 of Fig. 33 and are here shown as fitting into an oval opening in one of the headers I28 A preferred form of tube is of an oval section throughout most of its length but having a circular section at one or both ends as shown at I56, thus providing a more convenient means for upsetting the tube into the header.

If the oval form of entrance to the header is used, it may be necessary to twist the tube ends to allow enough metal between adjoining tubes. This twist of the tube is shown at I51. The change from fiat to circular section is shown in Figs. 34 and 36 at 58.

The term oval section is used in a general way and does not necessarily mean elliptical, it all depending on the inost'convenient way of rolling the tubing. As shown it has been assumed that circular tubes would be taken and flattened to the most convenient shape, the peripheral length being the same in both cases the ends shown as rounded. There is the possibility that tapered ends and slightly curved sides may be rolled more economically, all depending on the internal boiler pressure that must be resisted.

In Fig. 30 supply header I25L, similar to I25R shows an outlet I60 attached by an inside bolt I6I to a T shaped piece I62L at the bottom of the ash pan forming two openings I53L that may be used as an ash-discharge. Doors below, such as IBIBL Fig. 31 close these openings.

. The other ends of this T are shown detachably connected to fiat hollow plates I65 and I66 designed toprotect the ash pan casing below and to likewise supply needed water to various risers. For instance, I65 connects to a flat, vertical riser I61 and protecting the front wall of said ash pan from excessive heat, besides supplying the horizontal header I68L.

Also, hollow plate I66 supplies a rear vertical riser I10 that feeds into a rear header I1IL.

Bolt IBI is similar in design to bolt M5. Also the header IBBR feeds into flattened tubes I393, discharging into a top header and then out through a water leg thimble similar to I32.

Flattened pipe I12 is similar to I69, while I13 is a hollow, water filled protection piece.

Pipe riser I08 may connect flat plate I66 with the lower arch tubes I06, as shown in Figs. 29 and 32. It will be observed that this piping system is in two longitudinal, disconnected groups and that a leak in one group will not affect the other. Should a leak occur in the right-hand system, valve I22R may be instantly closed preventing a draining of the boiler. The non-return valve I36R prevents the flow of the water and steam back to the fire box while repairs are being made.-

In Fig. 23 is shown an oil-burner I85, an oil supply pipe I8I and a valve controlled steam pipe I82 to operate it. This may be used to start the boiler, afterwards to be cut out when the coal is ready to ignite and started up again during stand-by periods when the locomotive has stopped running, it not being always economical to keep the coal burners running even at a reduced speed. The amount of oil burned is only that required to keep up the steam pressure and. to maintain a heated combustion chamber, ready to ignite the coal whenever the latter is turned on.

In Fig. 24 it will be noted that hot gases and ashes in suspension on leaving pass 12 are deflected into the bottom pass 13.

This pass shows a much larger cross section and the gas velocity is greatly reduced, thereby permitting some of the travelling ashes to fall into the water screened ash pan below.

Referring back to the second stage air heater 46 of Fig. 21, wherein the air stream discharges both to the tender and to the rear top of the boiler it may be advantageous to carry air at two different temperatures to these points. stance, the discharge to the tender at outlet 49, employed to force the coal into the burner 55, travels the longer and more exposed route and it might be the more economical to keep it at a lower temperature to prevent excess radiation, while a higher degree of heat through passages 96 and 91, directly to the burner might greatly aid ignition at that point.

To accomplish this I have added features to this heater which are shown diagrammatically For in through 91 to the burner 65 (not shown).

other damper252 opens or closes a rear passage 7 air from 38 is separated so that part' may flow past1damper l and below 258 and out at '49 to 'the tender or otherwise. j'The remaining air that 'passesabove' 258 is warmed by the greater ,surface of heating elements to a higher temperature and goes into 98past the damper '99 and 253 between the upper and'lower portions of the heater casing. r

Y o By opening 252 agreater amount of air may pass 7 7 Also by" closing damper 99 and opening 252 all the air goes .through49and at a' higher temperature.

7 maybe desired.

' v Imperfect or unbalanced combustion in other parts of the firebox might call'for additional amounts of air as for instance, in'the last'pass of the fire box. To supply such varying amounts it may be necessary tobleed off air from some source, as conduit, Figs. 23 'and 24 into passages-254 controlled bya damper 255 and through a thimble 256 in the rear boiler leg 13, and'beneath baffle 15 that may be used to diffuse the incoming air into the third pass"; 7 1

another system that may'beuse'd'as an alternate,

; or inconjunction with this preferredtype; This is shown in Fig; 39, a drawing essentially similar to that of Fig. 21." r I The air of combustion from the fan .or blower j 28 while travellingtoward heater 48 may be used to rotatea propeller device260 within the con- 'duit 29, that will in turn actuate a governor-like control 26L The propeller speed varies directly as the air velocity within 29, as does28l. This governor may be adjustedso that at a predeter mined velocity, an electric contact may-be estab-- lished that causes current to passthrough'wires 282 and energize solenoid-263; This solenoid will rotate or otherwise operate damper 83, thus automatically controlling the hot gas escape out of 82 as required by the air supplied to the heater 46,

this amount varying as the velocity of the air.

Several different rotative positions of 83fmay be established, by having a correspondingnumber of different electrical contactsifor different speeds of reliability of operation at all in doubt. I

the governor. Alsof26| may be used 'to supply steam that may directlyoperate damper 83. 7

Attention is drawnto the details of improve- 'ments as applied to theffirst'stag'e heater26 asinstalled on the forward 'partof the locomotive,

Figs. 9' to 20. As before stated, the success of the "ing, while its practicability will be questioned if maintenanceis excessive, accessibility difficult', or

The top of rear section 26B of this heater has been made parallel to the boiler barrel lso as to' spaced by the connection. 292 at the lower edgeof v the side sheets, through which both steam and contain curvedsteam tubes 215 assembled in pairs, as in Fig; 15 and detailed .in Fig,- 18, said side of'the enclosing casing and be symmetrical .in ,Fig. 38. A partition. :50 divides the heater easing into upperand lower portions. Incoming 8 Vertical pipes 211 connect and support these,

headers, receiving steam from a supply header as 218 which may also be used as a drain for the condensate. Pipe 211 is fastened to the base piece of each header and enters freely thetop of the header below, which bears on a shoulder 219 attached to pipe'211 and making a steam tight joint.

. A removal of the top of heater casing 280 allows each group of tubes 215 and attached headers 218 to be lifted out for repairs.

Each pair of tubes, has been passed through numerous flat, thin plates 28l attached by solder- I ing, brazing, etc;, so "as to transmit heat from the radiating or heating surface for the air to come in .contact with. The sizeand spacing of the tubes and the dimensions ofthe plates will determine tubes to the plates and thus provide a maximum theefiiciency of theinstallation as will the loss or increase'of head due to frictional air resistance.

Each header 216 has a number of pairs of bent tubes as shown in Fig. 17, nine pairs to each ,head' er. being here shown. Each header is supported Each'header 216 shows a removable'basepiece 282 for cleaning and allowing access to the tubes 215 for calking, upsetting, etc. The loose fit as at flange 219 should allow for lateral expansion,

ing headers 216 which feed into tubes 215, the

condensate flowing back into 216 down. 211 and into pipe 218 and outlet 283 to a later described conduit. Valve controlled air-vents (not shown) may be used to prevent air-bound conditions of the tubes 215.

The top or the forward section, 28A'of the heater has been made toconform to the outlines of the cold air entrance of the bell-mouth 40,

Figs. 3 and 4. Fig. l6is a general cross section of I 26A showing the groupings of the contained fiat hollow plates or heating units, the scale beingtoo small to show a suflicient number of plates to each group.

' Fig.'20'isatop plan of a grouping of five plates that is self cont'ainedready to be detached and 7 taken out through the removable top casing 286 ofrFig. 16. It is a foreshortened plan View of the essentially similar three plate groups 281 of Fig 16. Heating steam is supplied by the pipe 288, steam then'enters the first plate unit 289 of any group from a circular riser 298 whose side is at- *tached to the front edge or endof 289. A portion of the top edgeof 289 is shown broken awa to show its proposed construction.

Each plate unit is preferably made of thin,

parallel sheets; suitably spaced 'as by. occasional stitch riveting, the ends of the sheets bent over and lapped together as shown at 29l. The rear part of 289 has'a side opening opposite alike opening in the second. unit, both being jointed and condensate may pass.

The front'end of this second plate unit has likewise a side connection 293 like 292 and leads The con wise connected to the fourth unit etc. densation is discharged from a fifth unit into a sump 294, thence to a drip pipe 295, that drains the other plate groups, finally discharging into outlet 296 of Fig. 9. Broken arrows show the flow of steam.

To provide proper steam circulation and the venting of any included air within these plates I attach across the tops of said plates a hollow member 291 having a small perforation entering each plate through which small amounts of steam may pass into 291, with access plugs 298 to clean perforations.

A detachable air venting piece 299 is shown connecting the removable plate unit groups, joining ends of 291, all feeding into one another and finally passing to the atmosphere through control valve 300.

Proper adjusting of the vents under 298 will cause the steam to flow to the top of the hollow heating plates instead of being confined to the bottom portions.

Riser 290 is to seat in a pocket in the pipe 288, that is made steam tight but allows the plate unit group to be lifted out for inspection. A like jointing to the drip pipe 295 is required.

In the part top plan, Fig. 10, the plate units are shown as 28'! and the fin-tube groups as 275. In Fig. 9 condensation from 296 of the heater portion 26A and condensation from 283 of the heater portion 26B discharge into pipe 302, through a one way valve 303, to a discharge point such as 304 in the boiler feed supply line 305.

In Fig. 9, 305 is the inlet water supply pipe to a boiler feed pump 306 that cooperates with a feed-water heater 301 that may be heated by steam supplied through conduit 308, and delivering hot water through pipe 309 and boiler check valve 3"] to the boiler.

Should but one feedwater heater unit be employed, the pre-heater condensate from the opposite or right side of the boiler can be delivered to the point 304 by the discharge of 283R and 296R. into 3IIR. and to a cross pipe 3I2 that passes through the boiler shell at the smoke box and empties into pipe 3IIL and to pipe 302 etc. Steam to operate the feed pump is supplied at 3l3.

Exhaust steam from the turbo-blower 28 may pass through pipe 3 l to the interior pipe 218 that supplies the air-heater tubes, etc. A branch pipe 3l5 controlled by valve 3!! may be used to deliver this steam to pipe 94 of Fig. 21 and thence to the jet in the secondary stack 4 (as has been described). Also heating steam from the main engine exhaust may enter pipe 3! controlled by valve 3I9, and pass into the air-heater as at 320, supplying conduit 288 of Figs. 16 and 20. Suitable by-pass connections (not shown) can be used to heat both sections of heater Hi from pipe 3 P5 or from pipe 3I8 as may be desired. A valve may be placed in the line between 218 and the entrance to 3H5.

The hot air outlet 21 from 263 is flattened and becomes quite narrow where it passes through the running board 5, to a. horizontal plane at 324 (Figs. 9, 10, and 13) where its cross section then alters to that of the joint at 325, where it connects with the inlet to the fan or blower 28.

This blower is hung or bracketed to the boiler shell I in a well known manner. Care in designing the discharge conduits and the transition piece 30, leading to the second stage heater 45, will smooth out the velocity-curve and cut down the friction head.

Speed control of the fans is preferably gov,-

erned through a steam throttle (not shown), and the correlation of this with the various feeds, dampers, secondary stack regulation and main engine control, all tend toward the production of a perfected thermal output.

Means for supporting the weight of the boiler on the new rear trailing truck are shown on Figs. 21 and 25, where a suporting bracket 330 attached to truck 9 with ball or roller bearings 33l receives said weight as through a shoe 332 shown attached to the mud ring 22 in any approved manner. a

It has been long recognized that the existing boiler-draft system of discharging the main engine exhaust through a restricted nozzle and into the stack and causing excessive cylinder back pressure, was extremely uneconomical, but so far it has been the most reliable. As to the use of mechanical-draft systems, it was found that an induced draft such as might be developed by installing a fan in the smoke box to draw gases through the fines, was unsatisfactory, as the high abrasive action of the flying cinders rapidly .destroyed the revolving blades of said fan.

Also, a forced draft fan required an air tight ash pan and fire box and when operated under the usual grate, either blew holes through the thinner parts of said bed, admitting unwanted cold air in too great quantities, or encountered too much resistance in passing through thicker parts of the bed and developing dead spots, requiring extra firing attention.

With the practical application of pulverized fuel, due to the ability of furnishing highly heated air to the locomotive boiler along with the successful installation of hot air fans or blowers operating the same, the grate is no longer needed, the finely divided coal being freely blown into the fire box and the resulting hot gases pass through the fire tubes and out of the stack, encountering a minimum of resistance. The power to overcome this resistance can be easily supplied, by the steam driven fans herein shown, thus removing this work from the main cylinders and employing them solely in moving the loc0mo tive.

A large percentage of former wasted power is saved while the stack exhaust becomes continuous and comparatively noiseless, with a minimum of spark discharge. A simplifying of the main valve setting which at present is at best a compromise, becomes possible, resulting in still further steam economy.

Both types of fans, induced and'forced draft, have recently been given road tests under service conditions and the locomotive tests have shown high percentages in fuel economy when compared with the alternate employment of a boiler draft as developed by the use of an exhaust steam jet in the smoke stack.

Besides the absence of an adequate sized fire box in which to burn the powdered coal while in substantial suspension and mingled with the hot air and travelling gases, the presence of the resulting ash in a finely divided state just before the entrance of the heated gases to the boiler tubes in quantities presented the problem of protecting said tubes from being clogged up. This is especially important when the tubes contain the super-heater elements which do not allow the passage of a tube cleaner.

My three-pass design for a fire box and low placed ash pan gives a longer travel for the fuel before it enters the fire flues, with more'time to be consumed, while perforated and inclined baftogether, make a harmoniouswhole that it would I fies in 'the lastiboiler'pass, assistedby'the 'described mushroom-shaped plugs before certain super-heater tubes,- serve to at leastpartly protect them, and also-to deposit ashes where they may be removed.

' pipe, being stronger against internal pressure 7 than would flat surfaces of greater area, the latter requiring considerable stay-bolting.

The advantages of the crown sheet protector are obvious andgive positive results as compared Qwith various proposed low-water alarms that neglect theusual precautions? ;The temperature of escaping'gas' from the ordimerely blow a whistle, leaving it to theeng ineman's attentionjto start up the boiler feed. Any

break downin a mere alarm is dangerous, as he hasbecome dependent upon it and consequently There; is noheat {lossfiir'r the 'second stage air heater operations as the heat bled from the fire box is later returned 'to'it by the extra heated air.

nary'locon otive smoke stack is about 550 deg.

Fahr. and it makes no'difference whether this escape occurs at the main'stack or through the secondary stack 4, if limited to the same tem- Y perature. A thermostat control attends to that feature. e V

11F01 the steam heating of incoming 'air, the first stage air heater has its heating units assembled'with a view towards quick inspection, re-

moval and repairs, as described. The innumer- I able'thin fin plates, soldered to the pairs of 1 curved tubes, truss each set against substantial deflection, and may be likewise: occasionally trussed at right angles with an adjoininggroup of tubes. I

Excess heating steam to-this heater may'es'cape in sufficient quantities to insure the carrying away of included air within, that might otherwise cause said heater to become air bound. Considerable l advantage is derived in the large'amount of pure steam condensate that may be return-ed to a. feedwater heater orto the boiler feed system, as

may be desired.

"The bell mouth and shutter attached to the inlet of this air heater, as'they do not extend beyond the locomotive outlines, only encounter the air resistance, that would-otherwise be 'met further on, and is therefore negligible, while at the same time, the developedair pressure'as'sists the fan in overcoming the, interior resistances of the heater.

The location of the first'heater ontop of the boiler and at the front where it gets the freely flowing air, aninterposed fan that is part induced'and part forced, and naturally placed partly below the boiler curve, and the followinglowe placed second stage heater with. its short-di stanced delivery to the fire box, all functioning be hard to improve on; r I v e The removal ofthe cumbersome steam nozzle from the stack, along with some other draft'de vices, will give. more room in the smoke box end andallow for a type of economizer placed-between the feedwater heater delivery and aboiler v check valve, giving a higher temperature of said feedwater if required, Though under boiler pressure and needing frequent inspection, the changes in the front-end construction will permit greater access to the samem'; 7

On Fig. 9 are shown an indicatedwaterpipe connection, 340i between said smoke box econoe mizer and a 3-way valve 34!. This valve is also. connected with feed pipe 399 and with boiler check'valve 319, and operates topass the water received from 369 entirely to valve 310, or to the economizer or to both these points of delivery at; thesame moment and in varying amounts, as may berequirecL. Thedischarge from the economizer to the boiler is preferably through another 7 check valve (not shown).

By a proper setting of valve SLvarying Water velocities through the economizer may be used and the resulting temperature of its discharge,

can be controlled. j V

Inusing exhaust steam in the first stage air preheater, a considerable percentage of otherwise lost'heat may be returned to the boilerall depending on the resulting temperature of the heated air.

. Again, another advantageof a reheating in the second 'stageheater lies in. the ability to produce quite a range in the final air temperature at the coal burner, choosing that limit which will most speedily cause the combustible to flash into flame,

Satisfactory powdered coal burning being a'ssured, a more'continuous' use of the locomotive maybe forecast. As compared with marineand stationary engine operations, locomotivesare in use during a very smallportion of the time,

stopping after, travelling a few hundred miles,

but keeping up steam at the end of the run until it i's time to return tothestarting point, often a stand-by of several hours, while the coal losses are considerable. I g. t 7

Such limited runs are largely due to the clogging of grates, the necessity of cleaning fires, etc.'- j

With the use of powdered fuel, the grates and other'adjuncts disappear and there seems to be no'reas onwhy' the new type of locomotive cannot immediately proceed on its journey. It may be'arranged at times to operate only one burner, while any prolonged wait would call for stopping all coal burners and the starting up of a small oil burner to provide for the loss of radiated heat and any lowering of boiler'pressure.

While new locomotives may be constructed to embody these inventions, it will be observed that my drawings havebeen made 'withthe ideaof improving locomotives at present in active use.

Marks Mechanical Handbookgl930 edition, lists the 2-8-4 type of locomotive shown on Sheet 1 of this patent application, as costing $100,000. Any substantial substitution of electric, gas elec- .tric or steam-turbine locomotivesfor thefpresent Steam locomotivesin use'would'cause an almost complete capital loss. on their present value, as there would be noother market for steam locomo tives. a

It is believed that my proposed improvements will prevent this, while providing economies far in' excess of any that 'wouldbe supplied by said substitutions, all theseimprovements costing but a small percentage of the value'of the existing locomotives. 7 i

Iclaim: if

1.'In asteam generator having a combustion chamber filled with hot gases and to which air? of combustion is supplied, means for preheating 'said air of combustion, said means comprising a i steam-heated; first-stage preheater capable of delivering its contained air of combustion to a a second-stage hot gas :h'eated preh'eatensaid hot gas being directly withdrawn from said combustion chamber and delivered to heating means within said second-stage preheater at substantially the temperature of the combustion chamber, said heated air of combustion being discharged into said combustion chamber.

2 In a steam boiler having a combustion chamber supplied with air to promote combustion therein, a steam heated air preheater, a hot gas heated air preheater that uses quantities of hot gas obtained directly from said combustion chamber at substantially the temperature thereof, and an interposed fan or blower means for withdrawing air from said steam heated preheater and forcing said air through said gas heated preheater and into said combustion chamber.

3. In a locomotive boiler, a combination or an air conduit including a firebox and a smoke stack connected therewith and constituting a substantially closed system having an air intake at its front end and discharging products of combustion from the stack, a first-stage air preheater adjacent the entrance end of said conduitheated by exhaust steam and a second-stage air preheater receiving warm air from the first-stage preheater and heated directly by the hot gases from the firebox at substantially the temperature of the firebox and delivering highly heated air to the firebox.

4. A locomotive boiler construction comprising a firebox, a first-stage air preheater for heating the air by steam, a second-stage air preheater for directly heating the air by firebox gases connected thereto, said first-stage preheater being located principally above the horizontal central plane of said boiler and placed forwardly of said second-stage preheater, said second-stage preheater being located principally below said central plane, the higher placed preheater being arranged so as to supply its contained air of combustion to the lower placed preheater and a fan located between the first and second stage preheaters for moving warm air through the first stage preheater and forcing the preheated air through the second stage preheater.

5. In a locomotive boiler having a combustion chamber with at least a first pass or ignition chamber to which the boiler'fuel is supplied, an air of combustion preheater delivering air of combustion to said boiler, means for dividing said preheater into unequal heating parts so that one heating part heats its contained air of combustion to a higher temperature than that of the remainder, and means for delivering this more highly heated air of combustion to said first pass or ignition chamber, and means for delivering the remaining cooler air to another part of the ignition chamber.

6. A locomotive boiler having a firebox and a boiler, an air preheater having an entrance opening forwardly and heated by steam, a second preheater heated by the products of combustion from the firebox and delivering heated air into the firebox, a blower located between the entrance and the second preheater for forcing air to the second preheater, a controlled stack for discharging products of combustion which affect the second preheater, the remaining products of combustion serving to heat the boiler, and a main stack. for discharging the latter products.

7. A locomotive boiler having a firebox, a first stage air preheater heated by steam, a second stage air preheater receiving air from the steam heated preheater and heated by part of the products of combustion at substantially firebox temperature and delivering the preheated air into the firebox, and means for accelerating the flow of air through the two preheaters, and means for discharging the products of combustion to the atmosphere.

EDMUND H. BLUNT.

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