US1764430A - Locomotive - Google Patents

Description

June 17, 1930. c. A, w. BRANDT 1,764,430

ILOCOMQTIVE Filed 19. 1925 4 Sheets-Sheet 1 INVENTOR.

w (JIFL A n. BRA/VET ATTORNEY.

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I-I-l-l-i June 17, 1930. C. A. w. BRANDT ocoMoTIyE Filed Jan. 19, 1925 4 Sh eets-Sheet 2 I NV EN TOR. (434. 4. W BBWVDZ' A TTORNE Y.

I I I I I I I I I I I I I I I I I I I I June 17; 1930.

c. A. w. B'RA NDT LOCOMOTIVE Filed Jan 19, 1925 4 Sheets-Sheet 3 1 N VEN TOR. (4/?4 .4. WB/P/I/VDZ' A TTORNE Y.

June 17, 1930, c. A. BRANDT LOCOMOTIVE 4 Sh s-Sheet Filed Jan 19. 1925 INVENT R 645A .AWB/FAA/D A TTORNE Y description proceeds.

l at ented. June 17", 1930 UNITED STATES PATENT orrlcr.

chm. A. .w. BRANDT, or GREAT nncx, NEW YORK, ASSI'GNOR 'ro 'rnnsurnnnnnrnn COMPANY, OF NEW YORK, N. Y.

LOCOMOTIVE Application filed January 19, 1925. Seria1 No. 3,538.

My inventionrelates to locomotive boilers and has for its general object the provision of a boiler havingan evaporating and superheating capacity. which is considerably greater per uni; of length than is obtainablein boilers of present construction, and which also has. a higher overall boiler efiiciency than is obtainable with present types. Other and further objects will appear as'the The constant demand for locomotives of =larger'unit capacity resulted first in the de--. velopment of locomotives to the maximum dimensions permitted by present road clearances, and further efiiciency and capacity were then obtained by the additionof various-boiler auxiliaries, among which is the In the earlier type of locomotives and in the majority now in use to which superheaters are applied, the comparatively small fire boxes and combustion chambers deliver the combustion gases to the fire tube section at a temperature very little below that of the fire box itself and with the high gas temperatures obtained inthe fire tubes of the boiler,- a comparatively small superheater is sufiicient to, give the desired degree of superheat. The advent of larger fire boxes and combustion chambers has increased boiler capacities and efliciencies by reducing the draft and cinder losses, and, b the absorption of greater quantities of radiant heat in the fire box section, reducing gas temperatures leaving the boiler.

The advantages just described are, however, reduced to a considerable extent by the fact that the lower gas temperature in the fire tubes necessitates the use of a larger superheater surface in order to obtain the desired degree of superheat. To accommodate the larger superheater'necessary to produce the desired super-heat, and to handle the increased quantity of steam which this type of locomotive produces, it is necessary. to

greatly increase the number of large flues into which the superheater units are inserted and this construction materially reduces the total heating surface of the' boiler. Fur

thermore, the fire tube superheater located in the flues of the boiler decreases to an apthrough the latterlmust be maintained at a temperature above that of the superheated steam. Present practice requires steam temperatures of 600 F. or higher, and as a re"- sult the combustion gases must leave .the flues at the uneconomically. high temperature of 700 or 800 F. The presence'of the firetube superheater headers andconnecting pipes in the smoke box end of the locomotive also precludes the possibility of allowing the combustion gases to pass from the fire tubes at a comparatively high temperature and thereafter abstracting from them their remaining useful heat by. means of an economizer placed between the forward tube sheet and the stack. Y

My invention, therefore, contemplates the provision of a locomotive boiler ofgreater evaporating and' superheating capacity per unit of length'than has heretofore been obtained, and which also has a higher thermal efiiciency, by. the re-arrangement and redistribution of the various heating surfaces of the boiler. The manner in which these ends-are obtained appears more fully in the following detailed description of specific;embodiments of my invention, illustrated in the.

accompanying drawings in which:

.Fig. 1 is a longitudinalvertical central section in a boiler constructed according to my invention;

Fig. 2 is a similar view on an enlarged scale of the forward end of the boiler shown in Fig.1; i

Fig. 3 is a transverse section taken on the Fig. 4 is a fragmentary horizontal section,

taken on the line 4 4 of Fig. 3;

Fig.5 is a View similar to Fig. 1{ of a modified form of boiler'construc d according to my invention; 7

to my invention;

Fig. 9 is a fragmentary plan view of a portion of Fig. 8;

Fig. 10 is a transverse vertical section taken on line 10-10 of Fig. 8, the superheater being removed for the sake of clarit Fig. 11 is an elevation of the settling ta used in the forms shown in Figs. 1 and 8, and

Fig. 12 is a vertical section through one o the individual tanks illustrated in Fig. 11.

Referring to the form shown in Fig. 1, my invention contemplates broadly the division of the heating surfaces of the boiler into fourmain units, so arranged that the flow of the combustion gases through them is counter to that of the water and steam, thereby obtaining the most efiicient heat transfer in accordance with the well known counter flow principle. The units of which the boiler is composed are substantially independent of each other in so far asthe circulation of steam and water within'the unit is concerned, and comprise a fire box unit, a superheater un t, a

Sembles a type which is in common use today, having two lateral water legs 1, and a rear water leg 2, with arch tubes 3 supporting 40 the arch, or battle 4, and witlithe top of the fire box being closed by the usual crown sheet-5. The fire box unit is extended/forward of the arch 4 a considerable distance to form-a: combustion chamber 6 of large 5 volume, and at the forward end the water space 'of-the unit is closed by the sheet7. Through the combustion chamber 6 and connecting the water space. above the crown sheetwith that below the floor of the 'combustion chamber extend the water tubes 8.

As will be-obvious, this form of fire box section, while similar in many respects'to the conventional form of fire box, provides a much larger area of heating surface exposed to the direct radiant heat of the combustion gases, which are cooled to a greater extent than-usual by the absorption of the radiant heat and leave the fire box at a temperature considerably below thatvat which they are 0 discharged from the ordinary form of fire box. It is further to benoted that my fire box unit is of a size which permits complete combustion, before leaving the unit, of even the long flaming bituminous fuel which is 05 generally used in railroad practice.

re tube evaporating 35 unlt, and an economizer unit.

The fire box unit of my locomotive re Upon leaving the firebox unit, thegases pass directly to the superheater unit, com-v prisinga chamber 9 located between the sheet 7 "and the tube sheet 10, andin which are located the tubular superheater elements to be described in detail later. By locating the superheater in this high temperature zone,

I am enabled to obtain the required degree of superheat with a superheater having a much smaller area of :heating surface and also a shorter path of steam travel than isrequired in the case of the firetube superheater. This results not only in a saving 1n space but also .in a reduction of the pressure drop through the superheater over the firetube form. It

"is possible to place the superheater in the position noted, without injuryto the supereatingelements because of the fact that the large radiant heat absorbing surfaces of the firebox unit prevent the passageof gases to the. superheater unit at an excessive temperature, and the tubes 8 form an efiicient .thermal screen between the superheater and the interior of the firebox unit.

By proper spacing of the water screen tubes 8 the superheater may be protected from excessive radiant heat, while at the same time a certain amount of radiant heat is allowed to penetrate to the superheater unit. By this arrangement I provide a superheater absorbing heat both by radiation and convection, which results in important advantages. A characteristic feature of the convection type superheater is the tendency degree of superheat, regardless of boiler" load, but has other limitations which make its use in locomotive practice undesirable. By combining heat absorption both by radiation and convection I provide a superheater which will deliver steam at a more uniform temperature over the full range of boiler ratings than will the convection type, and avoid the defects inherent in the purely radiant heat type. It is also to be noted that the arrangement provided permits of great flexibility in design, as by varying the-number of rows and the spacing of the tubes 8, the amount of radiant heat passing to the superheater unit may be controlled, and any superheat characteristics desired may be ob-- tained in a given design.

Forwardof the superheater unit, I provide the firetube evaporating unit composed of the tube sheets 10 and 11, the cylindrical sheet 12 forming the main barrel of the locomotive, and the firetubes .13. By this arrangement, the combustion gases, which have been considerably cooled by -their passage through the firebox and superheater units, are brought into contact with evaporating to produce a low degree of supprheat at low its surfaces, the water side of whichis not above the comparatively low temperature of the saturatedsteam. The rate of heat transfer 1n this unit, by convection from gases, at a moderate temperature, is much lower than that obtained inthe' firebox and superheater units, and in order to abstract the useful heat from the gases in this unit of the boiler a very large area of heating surface is desirable. Furthermore, it is desirable to obtain I through this, as well as all other portions of the boiler, the maximum free gas area, as experience and tests have shown that this latter factor is a direct measure Of'the capacity obtainable from a given size of boiler.

By my construction I am enabled to attain both of these desirable ends, as by the elimination of the firetube superheater, I-a'm able to use a large number of small diameter firetubes instead of a smaller number of the large flues necessary to accommodate the ele- -ments of a firetube superheater, and, in addition, I have available a larger flue sheet area for the insertion of tubes than is the case in the ordinary form of boiler. This latter advantage may be readily appreciated from a consideration of Fig. 6 and 7. In the ordinary form of locomotive boiler the 'rear tube sheet form the forward end ofthe firebox chamber and the size of the sheet is reduced by the water legs at either side of and below the firebox and the water space over the crown sheet. The maximum tube sheet area istherefore, in the ordinary form of construction, limited to the cross sectional area of the forward end of the firebox, which is clearly shown as the space bridged by the tubes 8 in Fig. 7. In'my construction the rear as well as the forward tube sheet has an area equal to thefull cross sectional area of the main barrel of the boiler, formed by thesheet 12 and, as illustrated in Fig. 6, this area, all of which below the water level is.

available for tubes, is manifestly consider ably greater than is. available the ordi 95 nary form of construction.

By the use of a large number of small diameter firetubes utilizing the full diameter of the boiler barrel, I obtain such a large area of heating surface per unit of length that I amable to abstract the remaining heat from the combustion gases at a temperature useful for evaporating purposes,

by an evaporating unit of comparatively short length, This, together with the absence of the firetube superheater headers and the attendant piping, leaves, in a permissible over-all boiler length, along and unobstructed smokebox 14 between the forward tube sheet .11 and the combustion gas outlet 15, in which may be installed an economizer, or, if desired, a combustion air preheatrr, for

the purpose of abstracting the remaining useful heat from the low temperature gases leaving the firetube unit. l

In one form, as illustrated on an enlarged scale in. Fig. 2, I employ an economizer in this space made up of a series of cast sections placed in parallel relation to each other, and transversely of the smoke box, each section comprising an upper header 16 and a lower one 17, the two headers being connected by a number of hollow bars 18 opening into the interior of the headers. These bars have, as more clearly appears from Fig. 4, a cross-shaped cross section and those of alternate sections are offset or staggered; those of each section extending beyond the limits of its header and to that extent overlapping and intermeshing 'with those of the adjacent section. The interior 'of the headers is suitably sub-divided b partitions 19 to give a zig-zag flow throug each section, and the sections are suitably interconnected by nipples 20 (as shown in Fig. 9) to give a series flo'w through the economizer. Baflles 21 close the spaces between headers 16 and 17 and the sheet 12 and force the combustion gases to pass order the economizer sections on their way to the outlet 15.

- In order to effect the maximum thermal efficiency, and also to prevent sweating of the economizer, with consequent corrosion,"

due to the introduction of cold feed water thereto, I prefer to preheat the feed water by means of an exhaust steam feed waterheater 22 which may be mountedin front of the gas outlet 15, as shown in Fig. 1. The"- specific form of the feed Water heater forins no part of the present invention, and need -not be described in detail. Cold feed water from the boiler feed pump (not shown).

evaporating efliciency. I have therefore provided a simple and effective means whereby the elimination of sediment and scale forming matter is efiected before its entr .into either economizer or boiler. A num r of vertical cylindrical tanks 26 are suitably mounted adjacent one side of the economizer, and a series of similar tanks 27 are mounted in the same manner on the opposite side, and

as may be seen from Fig. 3, the, main sheet 12 is so arranged at this point that the tanks 26 and 27 lie closelyadjacent the economizer sections and do not protrude beyond the altanks26; and is fitted with the usual blowoff lowable clearance limits of the locomotive.

Referring to Figs. 11 and 12, the construction and arrangement of "tanks 26 is shown in detail. Each of the tanks 26 is provided with a conical member-28 open at its base and extending through the top of thetank,

' the several members 28 being connected to a common manifold 29 which is, in turn con- 7 nected to the pipe 24 leadingirom the feed the form of carbonates.

water heater. A second manifold 30 is connected to the upper portion of each of the tanks 26, and at its other end is connected to the first economizer header 16, as-clearly appears in Fig. 9. A blowoff manifold 31 is connected to the bottom of each of the valve 32.

The construction and arrangement. of tanks 27 is like that of tanks 26, except that the manifold 33 (Fig. 9) connectin ,the interior conical members is connecte tothe last header 16 of the economizer, and the manifold 34 connecting the upper portion of the tanks 27, leads through the connecting pipe 35 tothe firetube evaporating section of the boiler. Tanks 27 are provided with a 'bottom blowoff manifold 36 and valve 37 water through members 28 and tanks 26 is' very low, and ample opportunity is provided for the sediment and carbonate precipitates to settle to the bottom of the tanks 26, from which they may be blown oil as desired, and the feed water then enters the economizer substantially free from sediment and carbonate impurities.

In passing through velocity, and is heated ordinarily to a temperature of 300 F. or more. Impuritles in the form of sulphates are precipitated atabout this temperature, and immediately upon leaving the economizer the feed water enters the tanks 27, where'these precipitates are allowed to settle out in the same manner as has been described in connection with the tanks 26, the purified feed water then entering the boiler. throughthe connection 35.

11 order to avoid complication, I prefer to have the economizer and feed water heater opergte at boiler pressure, and for this reason provide the settling chambers in the I the economizer, the passages of which are serially connected, the feed water travels at a comparatively high form of a number of cylindrical tanks con-' nected in'parallel, as this means enables me to secure the necessary lar e flow area with apparatus which may be c eaply and easily constructed from standard materials, and which 'will also easily withstand boiler pressures.

-Referring again to Fig. 1, it may readily be seen that the firebox and fire tube units ofthe boiler are inde ndent of each other in so far as circulatlon connections are con cerned, and in order to supply-water to the firebox unit and also'to' equalize the water levels in the two units, I provide the connecting pipe 38, which forms the sole connection between the two units below the water level thereof. A flexible expansion joint 39 I is provided in the pipe 38 to take care of any stresses which may be set up therein.

It is to be understood, however, that this connection between the two units need not be limited to a single pipe, but may be efiected by a lurality of similar connections.

It is further to be noted that the steam spaces of the firebox unit and the fire tube unit are separate. The steam liberated in the firebox unit is taken off from the steam dome 40 by the steam pipe 41, while that formed in the fire tube unit is taken ofi from the steam dome 42 by the steam pipe 43. The

steam ofi'take pi es 41 and 43 connect respectively with t e. superheater headers 44 and 45, which are respectively connected by tubular superheater elements 46 and 47 to a common outlet header 48, to the flanged outlet of which is secured the throttlehousing 49.

The superheater elements 46 and 47 are made up of loops, the ends of which are secured in any desired manner to the headers, with the loops providing, the -possibility of movement of the several headers relative to each other, which is necessary on account of the rigid attachment of the headers 44 and 45 to their respective steam domes. The headers, it will be noted, are out of the direct line of the gas travel and the connections between them and the superheater elements are thus protected from extreme temperature conditions.

I Referring now to Figs. 5 and 6, I have shown a sli htly difierent form of boiler, in i which the rebox and superheater units are constructed and arranged in the same manner as in the form shown in Fig. 1, and in which the fire tube unit'is modified to accommodate a difierent type of economizer. In this form the fire tubes are longer than in the form shown in Fig. 1 apd the forward ends of the central tubesare enlarged, as

. at 13, to accommodate the economizer elements, which are of the tubular return bend type commonly used in firetube superheaters.

In this form the economizer comprises an upper transverse drum 50 and a lower similar drum 51, the two drums serving as headers which are. connected by a plurality of economizing elements 42. Drums 50 and 51 are divided by partitions 53 to give a water receives its initial heat in the heater 22; It then passes serially through the drums 50 and 51 and the elements 52 to the boiler. Because of the large diameter of drums 50 and 51, the velocity of the feed water passing through them is very low, and

the sediment and precipitates formed by the heating both in the preheater and the economizer have ample opportunity to settle out in the drums, from which they may be blown off through the blowofi connec- It is to'be noted that this form of economizer is not open to the objections applicable to a superheater in this location, as the temperature to which the water must be heated is much below that required for the steam, and a much smaller sectional flow areaof economizer is required than is required in a superheater. Consequently, with an economizer in this position, the combustion gases may still be reduced to an economically low temperature in the fire tubes, and the sectional area of the economizer does not cause a serious diminution in the free gas area through the tubes, as is the case with av superheater. The-slight loss in heating surface per unit length in the fire tube section due to the enlargement of the tubes (which need not be so large as those necessary to accommodate a superheater) is compensated for by thefactthat the firetubes may be made longer than in the case where an economizer of the type shown in Fig. 1 is employed.

In Figs. 8 to.10 I' have shown a third form of boiler which in thegeneral arrangement of the units is similar to that shown in Fig. 1, but in which the form'of water and steam connections between the firebox and the fire- 'inner water leg walls of the firebox unit A with the rear tube sheet of the fi'ret be unit Above the horizontal diameter of the boiler tube units has been modified. In some forms of locomotives, the proximity of the running gear to the. under side of the boiler shell makes the use of the outside connecting pipe or' pipes 38 undesirable and such cases, I provide an internal connection be tween the two sections below the water level thereof, which functions inthe same manner as the external connection. In this form the maincylindrical sheet is belled out on the lower side of the boiler, as-at'12, and a tapered semi-cylindrical sheet 55 is provided inside the main sheet, connecting the the sheet 55 is carried vertically upwardiuntil it meets the main boiler sheet, to which it is suitably secured along the line indicated at 55 in Fig. 8. The space between the sheet 55 and the main boiler shell provides a water passage 56 connecting the firebox with the firetube unit, and it is .to be noted that the passage 56 is closed by the juncture and the maximum number of fire tubes em- In the boiler shown .in Fig. 8 I have also shown a-modified form of steam ofitake. According to this arrangement, the steam domes on the firebox and fire tube units may be omitted, and the steam liberated in the firebox section, instead of being delivered directly to the superheater, is carried by means of one or more conduits 57 to the steam space of the firetube unit, these conduits forming the only connection between the. two steam spaces. Steam from both units is carried to the superheater by the conduit 58, which connects the forward end of the steam space of the fire tube unit with the superheater inlet header 59, and in which may be placed the steam separator 60. The header 59 is in the form of a Y the branches of which embrace the outlet header 49', and to which they are connected by the tubular superheater elements 46 and 47'. Header 48 connects, through the throttle 49', with she conduit 61 leading to the engine cyliners.

It will thus be seen thatfwithout departing from the usual exterior form of locomo- ,tive boiler, which enables me to mount the customary boiler auxiliaries inthe ordinary manner, and without employing any structure which cannot "be cheaply and easily steam producing. unit, and in my"construction this characteristic is assured by the fact that no water reaches the firebox unit until it has first been brought to theevaporating temperature, by passage through the fire tube unit,'which is at evaporating temperature and producing steam. In this connec=v tion it is to be noted that the firebox unit is by far the greater steam producer of the two units, and the rate of evaporation in this unit is very high. As a consequence, lar e quantities of water are required by this unit, which 'is moreover sensitive to changes in steam demand and the rate of firing, and the-varying demand forwater in the firebox unit is readily met by the large reserve of By my arrangement of units, I assure a supply of water to the firebox unit that is substantially pure and free from scale forming impurities, as the firetube unit provides a reservoir of comparatively slow moving water inwhich any residue of impurities,

- because of the fact that impurities may be which may not have settled out in the chambers provided for the purpose, may be precipitated. This is of advantage not only removed more easily from the fire tube unit than from the firebox unit, but also because evaporating surfaces of the fire tube unit,

' being exposed only to gases which have been cooled by passage through the firebox and superheaterunits, are not so likely to be injured by overheating due to scale accumulations on their inner surfaces as are the evaporating surfaces of ,the firebox unit, whichv are directly exposed to the intense temperatures of the furnace and combustion chamber.

I provide fora considerably increased free gas area through the boiler without an increase in its diameter, because of the removal of the superheater from the firetubes, thus permitting the use of small diameter tubes, and the provision of tube sheets which. extend across the full diameter of the boiler shell. This increase in free gas area may amount to as much as twenty-five or ,thirty per cent. By the removal of the superheater from the discharge end of the firetubes, I am enabled to reduce the gas temperature at this point to a degree approaching that of the boiler temperature without in any way ine afiecting the degree of superheat obta and because of the free space available at the smoke box end of the boiler, I amable to utilize an economizerwhich will reduce the flue gas temperature to a still lower degree before its discharge through the stack. By this arrangement of the various units of the b,oiler,I utilize to the fullest possible extent the counterflow principle of heating and am able to reduce the gas temperature at the boileroutlet to the] lowest possible degree,

without impairing the efliciency of any unit I provide a superheater which, with the minimum amount of heating surface, is capable of producing high degrees of superheat, which also has the large steam flow area necessary to handle the steam requirements for a large locomotive without causing objectionable pressure drop, and which at the same time does not restrict the free gas area through the boiler. The superheater is furthermore so located as to be readily accessible for inspection and repair, and by disconnecting the steam connections may easily be removed by an overhead crane, through the top of the boiler shell, for overhaulingor replacement. Furthermore, the superheater chamber 9, which may be entered through suitable removable cover plates in the main boiler shell, provides space from which the rear tube sheet may be inspected and repaired.

In the forms shown in Figs. 1 and 5, an important advantage is gained in the protection of the superheater elements during firing up periods by a flow of steam therethrough. As will be noted, the connections through the superheater form the only communication between the steam spaces of the firebox and firetube units, and as the former produces steammuch more rapidly than the latter, a considerable flow of steam will take place from the firebox to the firetube unit, through the superheater, to equalize the pressure between the two units. This steam flow acts as a protection for the superheater elements against overheating during the firing period, when the throttle is closed, and there is no normal fiow of steam through the superheater.

. v In the form shown in Fig. 8, the additional superheater protection just described has been omitted and a steam piping arrangement has been provided which will insure dry steam entering the superheater even under the most severe operating conditions tending to produce boiler foaming or priming. In this case, the steam being taken off from the firebox section, where there is the most violent ebullition does notpass directly to the superheater, but through the conduits 57 to the steam space of the comparatively quiet fire tube section from whence it is taken to the superheater through'the conduit 58, which is connected to the steam space of the fire tube unit at the forward end thereof, where there is comparatively little steam eneration to. cause disturbance, and where t e entrance of the feed water from the economizer further tends to produce a quiet zone suitable for dry steam removal.

As an additional precaution, the steam stantially completed and having a combus-= tion gas outlet substantially coextensive with the cross-sectional area of said chamber, a plurality of rows of vertical water tubes joining opposite water spaces of said unit adjacent said outlet, said tubes being spaced to permit a portion of the radiant heat generated in said chamber to pass through said outlet; a superheater unit over which the combustion gases pass located adjacent and extending across substantially the entire area of said outlet; a fire tube-evaporating unit located forwardly of said superheater and comprising a Y plurality of V closely space small diameter tubes distributed over the entire crossesectional area of the boiler below the water level thereof, whereby maximum, heating surface is obtained in the fire tube unit with minimum tube length, a long unob- 5 struc'ted smoke-box located forwardly of said fire tube unit, an economizer located in said smoke-box, a feed water heater, conduits for delivering feed-water through the economizer from the feed-water heater to the fire" at least two passes through said furnace, a

combustion chamber extending rearwardly -of the furnace and terminating in an outlet substantially co-extensive with the sectional area of the chamber, and a plurality ofwater '55 tubes joining the top and bottom water spaces of said unit adjacent said outlet, said tubes beingspaced to permit a portion of the radiant heat generated in said chamber to pass through said outletya superheater over which the combustion gases pass located adjacent and extending across substantially the entire area of said outlet whereby it is exposed to direct radiation from said chain her, a fire tube evaporating unit through which the combustion gases pass after leav ing said superheater, an economizer located forwardly of said fire tube unit and through which the combustion gases pass after leav-' in said unit, means connecting the water spaces of said units and means for delivering steam heater.

3. A locomotive boiler formed by a fire generated in said units to the super-.-

box unit, said unit comprising a locomotive type furnace having substantially greater length than width, arch tubes extending over said furnace, a baflle supported by said tubes and extending forwardly from the rear ends thereof to form the furnace roof, a long combustion chamber extending rearwardly of said baflle and terminating in an outletsubstantially coextensive with the sectional area of the chamber, and a plurality of water tubes joining the top and bottom water spaces of said unit adjacent said outlet, said tubes being spaced to permit a portion of the '.radiant heat generated in said chamber to pass through said outlet; a superheater over which the combustion gases pass located adjacent and extending across substantially the entire area of said outlet, whereby it is exposed to direct radiation from said chamforwardly of said fire tube unit and through ng steam generated in said units to the superheater.

v4. In a locomotive-boiler, in combination, a firebox evaporating unit, a second evaporating unit spaced therefrom, and through which the combustion gases flow after leaving said fire box unit, means connecting said units below the water level thereof, and asuperheater located in the space between said units, said superheater providing the sole communication between the steam spaces of Said units.

5. In a locomotive ,boiler, in combination, a fireboxevaportingu'nit, a second evaporating unit spaced therefrom, and through which the combustion gases flow after leaving said fire box. unit, means connecting said units below the water level thereof, and a superheater located in the space between said units, said superheater forming a flexible. connection between the steam spaces of said units.

. 6. In a locomotive boiler, in combination,

a firebox evaporating unit, a second evap orating unit spaced therefrom and through which the combustion gases flow after 1eaving said fire box unit, means connecting said units below the wate level thereof, and a superheater located -i the space between said units, said superheater comprising two inlet headers, a single outlet header, 9. plurality of superheater elements connecting said headers, and means connecting each ofsaid units to a single inlet header.

7. In-a locomotive boiler, an evaporating unit terminating inv a forward tube sheet, a main shell forming a part of, said unit and extending forwardly therefrom to form a smoke box section having a combustion gas outlet, an economizer located in said smoke box section intermediate said tube sheet and outlet, said economizer comprising a plurality of serially connected sections set transverselyof said smoke box and occupying the full rectangular cross section thereof, and bafiles closing the spaces between said shell and economizer, whereby all the combustion gases are forced through the latter.

8. The combination as set forth in claim 7; the individual. sections being integrally cast and comprising top and bottom headers,

' hollow bars connecting said headers, and

partitions in said headers whereby a serial flow is obtained through said sections from the inlet tothe outletthereof.

9. The combination as set forth in claim 7; said sections comprising a plurality of hollow cross-sha ed bars forming water passages throug said sections, the bars of adjacent sections being staggered with respect to, the direction of gas flow therethrough, whereby a zig zag gas flow is produced.

- 10. The combination as set forth in claim 7; said sections comprising top and bottom headers connected by vertical hollow cross shaped barsg-the bars of adjacent sections being st aggered with respect to the gas flow with the extending arms of the bars of adjacent sections in over-lapping and intermeshing relation.

11. In a locomotive boiler, the combination of an evaporating unit, a feed water heater and an economizer, means for delivering feed water to the evaporating unit through the feed water heater and the economizer serially in the order named, said means including a primary settling space between the feed water heater and the economizer, a secondary settling space between the economizer and the evaporating unit, and means for removing the impurities deposited in said spaces.

i 12. In a locomotive boiler, the combination of an eva orating unit heated by combustion gases, a eed water heaterdn which the feed water for said unit is heated by exhaust steam from the locomotive engine to substantially exhaust steam temperature whereby the precipitation of some of the impurities in the feed water is effected, an

economizer in which the feed water is heated by the ,combustiongases to substantially evaporatin temperature at boiler pressure whereby t e remaining impurities inthe feed water are precipitated, a conduit connecting the feed water heater and' the economizer, means forming a primary settling space in said conduit in which the impurities precipitated in the feed Water 'heater'are deposited, a second conduit con- 13. In a locomotiveboiler; the combination with a fire tube evaporating unit and the main boiler shell extending forward therefrom to form a smokebox section; of an economlzer located withln said smokebox section and delivering feed water to said fire tube unit, a feed water heater, a connection from said feed water heater to said economizer, means adjacent said economizer forming a primary settling space in said connection, a connection from said economizer to said fire tube unit, and means located adjacent'said economizer forming a secondary settling space in said last named connection:

14. In a locomotive boiler, in combination, a fire tube evaporating unit, amain boiler shell, extending forwardly therefrom and forming a smoke box section, an economizer located within said smoke-box section and occupying the full rectangular cross section thereof, a feed water heater settling chambers at either side of said economizer, said main boiler shell being constructed and arranged adjacent said economizer to pernut said settling chambers. to lie closely adjacent saideco'nomizer and at least in part Within the circular outline of said boiler shell, and means forming a feed water path from said feed heater to said fire tube unit,said means thereof, an economizer located in said smokebox section occupying substantlally (the entire space between said flat portions of said shell, a series of vertical settling tanks mounted in the recess formed by the flat portion on one side of said shell'adjacent said economizer, a second series. of vertical settling tanks mounted in the corresponding recess on the other side of said economizer, a feed water connection leading through each of said first series of settling tanks to said economizer, and a feed water connection leading from said economizer through each of said second series of settling tanks to said fire tube unit.

' 16. In a locomotive boiler, in combination, a fire box evaporating unit having a combustion'gas outlet with water spaces above and below said outlet, a plurality of rowsof vertical' water tubes connecting said water [spaces and extending across said outlet; a fire tube evaporating unit spaced forwardly from said fire box unit and comprising a plurality of fire tubes distributed over the entire cross-sectional area of the. boiler below the waterlevel thereof; a superheater unit located in the space between said first-named units and com rising a pair ofinlet headers and an outlet eader, and a plurality of vertical return loop superheater elements 'c onnecting each of said-inlet headers with said stantially completed and having a combusthe cross-sectional area of said chamber, a

- plurality of rows of vertical water tubes has outlet header, all of said headers being located above the level of said fire tubes and said upper water space; abaflle bridging the space between said fire box unit andsaid fire tube unit below said headers, means connecting the water spacesrof .said evaporating units, and means for delivering'steam generated in said evaporating units to said inlet headers.

v 17 In a locomotive boiler, in combination, a fire-boxunit formin a furnace and combustion chamber in WhlCh combustion is subtion gas outlet substantially coextensive with joining opposite water spaces'of said unit adjacent said outlet, said tubes being spaced to permit a portion of the radiant heat generated in said chamber to pass through said outlet; a superheater unit over which the combustion gases pass located adjacent and extending acrosssubstantially the entire'area of said outlet; a fire tube evaporating unit located forwardly of said su erheater and comprising a plurality of c osely spaced small diameter tubes distributed over the entire cross-sectional area of the boiler below heater,

the water level thereof, whereby maximum heating surface is obtained in the'fire tube unit with minimum tube length, along unob- 'structed smoke-box located forwardly of said fire tube unit, a feed water heater, an econo mizer located in said smoke-box, and means for delivering all of the water fed to the fire-box section ,through the feed water economizer and I fire tube section serially in the order named.- Y p CARL A, W. BRANDT.

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