US2048373A - Steam generator - Google Patents

Description

July'zl, 1936. M. B. CARROLL STEAM GENERATQR 4 Sheets-Sheet 1 Filed March 51,. 1934 7 INVENTOR Mme/5 15. 07mm.

TTOIIQNEYS July 21, 1936. M. B. CARROLL STEAM GENERATOR 1934 4 Sheets-Sheet 2 Filed March 31 ATTORNEY July 21, 1936. B; RR L 2,048,373

STEAM GENERATOR K Filed March 31, 1934 4 Sheets-Sheet 5 -INVENTOR Mam /.5 fif/lBFOLL ATTORNEYS July 21, 1936. M. B. CARROLL STEAM GENERATOR Filed March 51, 1934 4 Sheets-Sheet 4 INVENTOR Mame/5 5. 64mm;

.- ATTORNEY Patented July 21, 1936 UNITED STATES PATENT OFFICE.

poration "of New York Application March 31, 1934, Serial No. 718,351

34 Claims.

' This invention relates to steam generators, and more especially to steam generators which are particularly adapted for use in automotive vehicles.

The invention is directed to improvements upon steam generators of the general type described and claimed in the co-pending application of Walter Douglas LaMont, Serial No. 631,703, filed September 3, 1932. Like the steam generator of said (lo-pending application, the steam generator of this application is directed to the solution of the problem of securing high capacity in a. steam generating plant adapted for use in automotive vehicles and especiallyof securing high capacity in a steam generating plant of comparatively small weight and of such dimensions that it will "occupy a'comparatively small space.

One of the purposes of the steam generator of the co-pending application, to the improvement of which the present invention is directed, is the provision of a steam generator of such low weight and high, capacity, and particularly of such high efficiency with respect to the amount of fuel required for its operation, that it can be utilized as a part of a power plant for aircralftf-As pointed out in the statement of invention of said co-pending application, .with the advent of high steam pressures and the development of high speed steam turbines and of eflicient and reliable reduction gears, the problem of using steam driven prime movers in aircraft, as well as in other automotive vehicles, has been simplified since such prime movers may now be built with less weight for a given amount of power vbecause of the high efiiciency of their operation. Moreover, in the case of aircraft, the use of reduction gears makes possible the operation of thepropeller at the most efficient speed, thus reducing somewhat the requirements of capacity in the prime mover.

The steam generator of the co-pending application hereinabove identified provides, in a compact and light weight unit, for the release in a combustion chamber of comparatively small size ofv comparatively large quantities of heat and for its so efdcient absorption by steam gen- 'erating,'steam superheating and air preheating tubes that relatively large quantities of high pressure steam can rapidly be generated with certainty, safety and the required continuity for aircraft operation. The steam generator of the present invention, while utilizing many, if not the most of the general principles of construction and operation of the steam generator shown and described in said co-pending application, aims to simplify the construction from the standpoint of the manufacture, assemblage and replacement of the parts, and at the same time to insure the required uniformity of operation together with increased eiiiciency. 5

The invention further aims to provide effective and substantially uniform heat exchange conditions at all points about the heating vehicle at any point in its path of travel through the generator so that every unit of space in the structure 10 will be eficiently utilized and that there will be a minimum of heat loss. To this end the invention aims to provide heat-exchanging apparatus for generating steam that is substantially symmetrical in substantially any transverse or longi- 15 tudinal section.

Another object of the invention is so to arrange the steam generating tubes along the path of travel of the heating vehicle that, while insuring a maximum of heat transfer, the power 20 required to insure the travel of the heating vehicle in heat-exchanging relation to the generating tubes at the desired speed will'be reduced to a practicable minimum for the space requirements of the structure. The invention also, aims 25 so to construct and arrange the steam generating tubes and the means for supplying waterto said tubes as to insure the travel therethrough of water and steam in such relative amounts that neither will interfere with the other and that 30 the tubes will be protected against burning. To this end the invention aims to provide substantial uniformity of conditions in different tubes exposed to the same heat conditions.

Another object of the invention is so to shield 35 all structural parts which do not carry water by parts which do that little or substantially no high heat resisting refractory material will be required in the generator structure, thereby further reducing the weight usually required in struc- 40 tures of equivalent capacity.

The invention also has for its object such im-' provements in the means for supporting the tubes and other parts of the structure that the desired relationship of'the parts may be maintained un- 45 der all heat conditions with a minimum of structural parts having merely supporting functions.

The steam generator of the present invention utilizes the principles of steam generation described and claimed in United States Letters Pat- 50 ent No. 1,884,979, granted October 25, 1932, and one of the important objects of the present invention is so to combine steam generating tubes, constructed and arranged to generate steam by the novel process of, said Letters Patent, with efii- 55 cient steam and water separating means and a steam superheater that in proportion to the size and weight of the structure and the total weight of the water subjected to generator pressure at one time, greater quantities of high pressure steam can be generated safely, continuously and emciently than had heretofore been considered to be either possible or practicable.

In devising a steam generator for the general purposes of the present invention, and particularly in devising a steam generator for use in aircraft, it is important not only that the parts be so constructed and arranged that a very high degree of efliciency will be obtained in a compact unit, but it is also important that the parts be so arranged as to permit ready removal for inspection and repair or replacement. The present invention aims, therefore, not only so to arrange the steam superheater elements with respect to the steam generating elements that the steam superheater tubes will be protected by the steam generator tubes and at the same time be so located as to effect the desired amount of superheating, but also so to arrange these parts in relation to each other that the steam superheater tubes may readily be removed without interfering with the steam generator tubes. The invention aims also to provide a construction and arrangement of the steam generator tubes themselves that will permit their removal, either individually or en banc, without substantial disruption of the structure as a whole.

Important features of the invention are the arrangement of the steam superheater tubes in such relation to the steam generator tubesthat the steam generator tubes protect the superheater against excessive heat on the side nearest the combustion chamber and protect the other side against loss of heat through the other flue wall and also the use of relatively long superheater tubes so coiled about the combustion chamber and about the generator tube assembly that an adequate amount of heating surface is provided and at the same time such a steam velocity is insured that a heat transfer rate sufficient to protect the tubes will result. This arrangement also has the further important advantage of prov1ding cross flow of the products of combustion over the superheater with the resultant turbulence, an arrangement which makes possible not only the desired control of the flow of gases over the superheater tubes, but also a similar control of the gas flow over the steam generator tubes between the legs of which the superheater tubes are located.

An important feature of the invention, which contributes to the symmetry of the structure as well as to its efliciency, is the utilization of what may broadly be designated as S-shaped steam generating tubes so constructed and arranged in the generator structure that the water in traveling through these tubes effects a series flow through both the radiant heat zone and the convection heat zone, the 8-shaped construction also providing for the hereinabove described shielding of the superheater tubes between two of the legs of the S.

Another important feature of the invention "which contributes both to the symmetry of the structure and to the uniformity of heat exchange conditions in the structure and which also facilitates the assembling of the parts and their removal for inspection, repair or replacement, is

the provision of a separate water wall covering that end of the combustion chamber where and direction of movement of the products of combustion is changedpso that not only is the radiant heat impinging on the combustion chamber end utilized to generate steam, but provision is made for the utilization also for this purpose of the intensive convection transfer which takes place where the direction of movement of the products of combustion is changed or reversed.

The invention embraces also improvements in details of the construction of various parts of the apparatus which contribute to lightness, facility in assembling, strength to resist high pressures, etc. Among such improvements to which attention may be directed is the tapering of the intake ends of the steam generator tubes to their points of juncture with the water header whereby a water header of a smaller cross section than would otherwise be possible may be used.

Other objects and important features of the invention will appear from the following descrip- 20 Figure 5 is a transverse section on the line 55- of Fig. 1;

Figure 6 is a longitudinal section on the line 6-6 of Fig. 5 of a detail of the construction;

Figure 7 is a transverse section on the line 1-1 of Fig. l of adetail of the construction;

Figure 8 is a transverse section of a part of the supporting structure on the line 8-8 of Fig. 6,

Figure 9. is a detail view illustrating the means for restricting the input into the steam generating tubes from the water headers.

Although many of the novel features of the present invention are equally useful in steam generators intended to generate steam at moderate pressures, the invention finds one of its widest fields of utilityin the generation of steam at high pressures and high temperatures. The illustrative embodiment of the invention is a steam generator designed to generate steam at relatively high pressures and at relatively high temperatures.

In order that such pressures and such temperatures may be obtained in a structure that is comparatively light in weight and comparatively compact in its dimensions, it is important that the steam generating tubes be of comparatively small diameter so that their walls need not be so thick and also that the travel of the water in said tubes in heat-exchanging relation to the heating vehicle be sufficient in length to insure the required steam generating heat exchange.

It is also important that advantage be taken both of the radiant heat developed in the combustion chamber of the generator and of the convection and conduction heat and that the exchanging relations between the heating vehicle and the water, but they also serve to shield the parts of the supporting and structure Patent No. 1,884,979, granted October 25,- 1932,

are so arranged about the combustion space 4 in a combustion or furnace chamber surrounded laterally by a cylindrical sheet metal wall 6 that these tubes form a water wall about the combustion space 4, each of the tubes 2 extending longitudinally of the combustion chamber-and being located in quite close proximity to the wall I 6. Each of the tubes 2 is connected at its intake end to a waterheader 8 which is preferably annular in form so as to permit a symmetrical arrangement of the tubes with respectto the cylindrical combustion chamber, water being delivered to the header 8 through a delivery pipe L8 from a circulating pump l2 to insure a sufflcient head of water in the header 8 to provide positive distribution to each of the tubes 2.

As shown in detail in Figure 9,. each of the tubes 2 is tapered to a reduced diameter at the end where it joins the header 8 and is provided at this end with a nipple or ferrule l4 having therein a passage I6 so determined in size with respect to the inner diameter of the tube, the heat to which the tube is exposed, the head of water delivered by the pump I2, etc., that water will be delivered to the tube 2 in excess of the amount that can be converted into steam in its passage through the tube, but not sufiicient so that the steamwill interfere with the water flow or the water will interfere with the steam flow. In' other words, the input is so controlled that steam will be generated in accordance with the process set forth and described in the Letters Patent No. 1,884,979 hereinabove referred to.

To insure that the joint between the tube 2 and the header 8 will withstand the high pressures to which the parts of the steam generator are intended to be subjected, it has been found that a suitable union may be made by providing grooves l8 in the sides of the hole in the header 8 into which the reduced end of the tube is inserted, the tube 2 then being expanded so that the material of its outer wall is forced into these grooves.

' To provide an adequate length of travel of the water in heat-exchanging relation to the heating vehicle in a generator structure that in itself is not excessively long, for example, that is not so long that it would be unsuited for use in vehicles, each generator tube 2 is shown as bent back upon itself so as to provide a leg 28 located in a flue 22 surrounding the combustion chamber 4 and having an outer wall 26 formed as a cylinder of sheet metal concentric with the wall 6 of the combustion chamber, the leg 28 also lying in close proximity to the wall-6 of the combustion chamber but upon the outer side thereof. The water wall section of the tube 2 is connected to the leg 28 by a curved section 28, of substantial radius, which serves at least, three purposes; first, it avoids a sharp bending of the tube material; secondly, it provides for an easy flow of the steam and water from the water wall leg into the convection leg and, thirdly, it permits, as shown, the interposition of a substantial heat exchange surface in the gas stream at the point where there is an abrupt change of direction in the flow of the stream with the turbulence incident there to, thus providing for a considerable heat exchange at this part of the path of travel of the water through the steam-generating tubes 2.

In order to insure still further length of travel of the water in the steam generating tubes 2 and at the same time to provide a shieldagainst heat loss for the steam superheater hereinafter to be described and protection also for the flue wall 26,.

the generating tubes 2 are preferably again bent back upon themselves in the flue 22 to provide a third leg 38, preferably parallel to the other two legs and preferably extending the whole length of the flue 22 in proximity to the wall 26 thereof. 8

Each of the generating tubes 2 preferably discharges into a common header 32 which, like the water header 8, is preferably generally annular in contour so as to permit a, symmetrical arrangement of the generator tubes and particularly of the legs 38 of these tubes, the annulus being, however, preferably interrupted at one point, as will more fully be described hereinafter, to permit the convenient removal of the steam superheater assembly. The steam and water header 32 is preferably located outside the flue 22 so as not to be exposed to the direct heat of the products of combustion, the legs 38 of the generator tubes 2 being bent as shown at 34 where theypass throigh the wall 26 of the flue'to join the header 3 Steam and water from the header 32 pass through a common conduit 36 to a steam and water separator 38, more fully to be described hereinafter, the water settling to the bottom of the separator 38 from whence it is drawn through a conduit 48 by the pump l2 to be delivered again to the water header 8. The substantially dry saturated steam from the separator passes through the conduit 62 to a series of superheater tubes 44, now to be described.

In the illustrative embodiment of the invention sixteenof these superheater tubes 44 are shown connected to the conduit 42, these tubes extending into the flue 22 and there being coiled about the combustion chamber, the coils of the superheater tubes being located between the legs 28 and 38 of the generator tubes. At their other ends the superheater tubes are connected to a steam conduit 46 from which the steam is led to the turbine or other prime mover.

It will be noted thatthe superheater coils lie crosswise of the path of travel of the products of combustion through the flue 22 and that successive coils are located in zones of increasing heat from the point where the superheater tubes enter the flue to the point where they leave the flue. It will also be noted that by reason of their position the superheater coils tend to set up turbulence in the gases passing through the flue 22 and thus increase the heat transfer both to the superheater tubes and to the steam generator tubes.

In order that their positions may not change markedly when heat is applied to the superheater tubes and they thus tend to expand, means are provided for holding them in fairly definite relations to each other in the flue 22 and also in fairly definite relations to the generator tubes and to the confining walls of the flue. The illustrative means comprise three perforated bars 48, 58 and 52, through the perforations in which the superheater coils extend whereby the coils are positively spaced with respect to each other and, in their upper sections, with respect to the walls 6 and 26 of the flue, the bars 48 and 58, as shown in detailin Figure 6 being provided with lugs 54 upon their edges which extend between two adjacent generator tubes into engagement with the walls 6 and 26 of the flue and thus positively position the bars, andv with them the superheater tubes, with respect to these walls.

The lower bar 52 is constructed to permit a limited movement of the tubes with respect to the walls 6 and 26 of the flue 22 as the tubes expand, this bar not filling up the entire width of the flue between the walls 6 and 26 and being mounted upon'spring-supported rods 56 extending through the wall 26. Springs 58 bearing against collars:

60 on the rods 56 tend to hold the bar 52 in its uppermost position but permit downward movement thereof as the superheater tubes expand with the heat.

The combustion or furnace chamber 6 communicates with the flue 22 at its rear end. In order to provide forthe easy flow of the products-of combustion from the combustion chamber 6 into the flue 22 and for their substantially uniform distribution to all parts of the annular flue, there is provided at the rear end of the combustion chamber 6 a wall 62 which is generally concave in form but has at its center an inwardly extending convex portion which serves to mushroom the gas stream so that it flows equally in all directions toward the periphery of the wall 62 and thus into the annular flue 22, with the outer wall 26 of which flue the wall 62 joins. For convenience in assembling the structure and in taking it apart, the cylindrical. edge of the wall 62 preferably telescopes slightly into the cylindrical wall 26, the telescoping of the two parts being limited by a rib 64 rolled up in the wall 62.

To protect the wall 62 from the intense radiant and convection heat from the combustion chamber 4, a water wall is preferably located in front of and closely adjacent to the wall 62, this water wall preferably extending up to approximately the point where the legs 30 of the generator tubes 2 leave the flue 22 to enter the header 32. The

water wall which protects the sheet metal wall 62 preferably comprises spirally coiled steam generating tubes 66, there being preferably four of these spiral tubes 66 leading out of a centrally located water header 68, as shown in Figs. 1 and 2. These steam generating tubes 66, like the tubes 2, are tapered to a reduced diameter where they join the header 68 and are provided with nozzles or ferrules which restrict the input of the water into the tubes so that steam is generated therein in accordance with the process described and claimed in U. S. Letters Patent No. 1,884,979, hereinabove referred to.

As shown in Figs. 1 and 2, these spiral generating tubes 66 are so coiled 'upon themselves that they follow the contour of the inner surface of the chamber wall 62 and each of the tubes 66 at its other end is connected to the steam and water header 32. Preferably, before entering the header 32, each of the four generator tubes 66 is bent to fit closely about a reinforcing and supporting ring 10 connected to the end of the cylindrical wall 6 of the combustion chamber and fitting between the waterwall leg and the first convection leg 20 of, the'generator tubes 2, the purpose of this bend 12 in the spiral generator tubes 66 being to provide for maintaining the ring 10 and with it the casing 6 and the assembly of generator tubes 2 in their concentric relation to the structure, four points of support from the header 32 thus being provided at equiangular distances about theaxisof the structure. The generator tubes 2 may be and preferably are also spot-welded to the ring I0.

The header 32, as just suggested, serves the additional function of a frame member for supporting parts of the structure, particularly in the form of the invention herein illustrated in which the steam generator is shown as having its main axis horizontal. It will be understood, of course, that the invention is not limited to an arrangement of the parts such that the main axis will be horizontal and that where conditions permit many advantages may be obtained by arranging the main axis of the structure in a vertical position, as for example with the burner at the top. In order to provide for the support of the header 32, it is preferably provided with a leg 14, as shown in Figs. 1 and 2, by which its weight may be caused to rest upon the floor or other base upon which the generator is mounted.

' Water to supply the header 68 may be taken from the water supply conduit l0 through a pipe 76 and thus be subjected to the pressure of the pump l2 to insure the desired distribution to the four generator tubes 66.

As the gases leave the flue 22, after having given up the greater part of their heat to the legs 26 and 30 of the steam generator tubes 2 and to the superheater tubes 46, they are preferably caused to pass in heat-exchanging relation to the air for the burner and to this end there is provided a second flue l8 communicating with the front end of the flue 22, the flue 18 being bounded on one side by the wall 26 of the flue 22 and on itsother side by a cylindrical wall 80 which is connected by a curved end 82 to the front end of the wall 6, whereby the gases from the flue 22 are directed in an easy curve about the front end of the wall 26 into the flue l8. Extending through the flue l8, and so spaced therein as to permit the flow of the gases thereover, are the air preheater tubes 84, these tubes at their ends being fitted into openings in two rings 86 and 88 which constitute respectively rear and front frame members of the structure as well as walls helping to define air passages. The rear ring 86 is provided with supporting feet 90 and the front ring is also provided with supporting feet 92.

The air tobe preheated in the preheater tubes 84 is preferably brought into the structure in such manner that it serves as insulation against radiation of the heat to the atmosphere and to this end this air preferably comes into the front end of the generator structure, passes through an air jacket surrounding the main parts of the structure and over the rear end of the structure and then into the rear ends of the preheater tubes 84. As shown in the drawings, the air jacket comprises an outer cylindrical shell 94 which is so spaced. from the wall 80 of the flue 18 that a substantially annular air passage 96 is provided between the shell 94 and the wall 86, this passage communicating at its front end with an air intake opening 98 in a casting J00 which forms a part of the burner structure and of the frame structure of the generator as a whole. For convenience of assembling the air jacket and of taking it apart, the cylindrical shell 96 may be flanged at its'two ends so that at its front end it may be connected to an annular casing member I02 of convex section. A similar annular member I!!! serves to connect thering 86 to the other side of the air intake as in the casting, mo and thus extendsthe air jacket over the front of the generator. I 3 At its rear end the cylindrical casing 94 is connected to the convex rear outer wall I66 0! the air jacket, this wall I06 forming the outer wall of a doughnut shaped air passage divided by a partition member I08 into two passages communieating with each other, the air coming in through the passages 96 being turned back by the curved wall IIO of the doughnut-like structure into.a passage II2 communicating with the rear open ends of the preheater tubes 84.

The partition wall I08 may be held in its proper relation to the rear wall I06 and the inner wall I I4 by any suitable means, the illustrated means comprising bolts II6 passing through all three walls I06, I08 and II 4 and provided between the walls I06 and I08 and between I08 and H4 with tubular spacers H8. Three of the bolts II6, with the associated spacers H8, spaced 120 apart about the axisof the generator will insure the desired relationship of the parts. i

To permit convenient removal of the rear structure as a whole, the outer wall I06 is preferably flanged to meet the rear flanged end of the cylindrical casing 98 and is riveted or bolted thereto as shown at I20. The partition member I08 and the wall I I4 of the inner air passage II2 are preferably provided with cylindrical portions at their peripheries which fit within the cylindrical ends of the rear curved extensions I22 andv I24 of the flue walls 26 and 80, ribs I26 and I28 being rolled up in the walls I08 and H8 adjacent to the cylindrical peripheries thereof to abut against the ends of the extensions I22 and I26 and thereby limit the telescoping movement of .the parts.

The products of combustion or heating gases,

after they have passed through the flue I8, go to the stack I30 which communicates with the flue I8, as shown in Figs. 1 and 3, the flue I8 being enlarged at its rear end where it joins the stack to the point diametrically opposite so that the v support'of the fluewalls 26 and 80. spacing members are preferably provided as .shown in Figs. 1 and 3, these spacing members comprising short sections of light I-beams I34, there being three of these spaced about the axis of the structure,

' as shown in Fig. 5, and located at the front end of the wall 26,- as shown in Fig. 1, and three more similarly spaced about the axis and located at A points intermediate between the ends of the wall- 26, as shown in Fig. 1.

In order to maintain the water header 8 in,

concentric relation to the generator structure, it is preferably supported by bracket arms I36 attached to the ring 88 by any suitable means such 1 as headed screws I38 tapped into the ring, said bracket arms being spot-welded or otherwise suitably secured to the header 8.

As hereinabove, pointed out, the casting I at I the forward end of the boiler constitutes both f apart of the frame structure and apart of the burner structure. The burner, which is not illustrated in detail but which may be utilized to supply the combustion chamber with anysuitable fuel, such as oil, has its main stem I40 prefer-f ably located substantially on the axis of the generator, the atomized 011 being directed by any suitable guide I42 into the stream of preheated putting sufflcient pressure upon the water to inair, supplied for combustion purposes, which comes in through the preheating tubes 84 into the annular space I44 about a. frusto-conical casing I46 which forms a part of the casting I00 and which has in it slots I48 through which the '5 preheated air enters the burner structure. The combustion air is directed into combustion. relation to the burner by a sheet metal frusto-conical casing I50 having its base attached to the base of the casing I46,'the casing I50 being preferably flared about the water header 8 and being connected to an annular shield I52 filling in the t space between the casing 'member I50 and the combustion chamber wall 6.

To protect the parts thus described against excessive radiant or convection heat from the combustion taking place in the chamber t, they are preferably shielded by still another water wall formed by a steam generating tube I54 connected at one end to the water header 8 and at its other end to the steam and water pipe 36, as shown at I56, this generating tube being coiled about the burner in a spiral formation that also conforms somewhat to the flare of the casing 56 and being extended also over the annular member I52, thereby effectively protecting these'parts from excessive heat while at the same time utilizing this heat to generate. steam; The generating tube E58, like the other generating tubes, will be provided with a nozzle or ferrule like that shown in Fig. 8 so that steam will be generated in the tube in accordance with the method described and claimed in U. S. Letters Patent No. 1,884,979, hereinabove identified.

From the foregoing description the operation ofthe device will readily be understood. The burner having been started in operation to supply fuel to the combustion chamber 4, for example, an atomized oil fuel, air is simultaneously forced into theair passage 88 by any suitable blower mechanism, not shown, so that it goes into the air jacket passage 86 through the inlet 88, then back through the passage II2, through the preheater tubes 84 into the annular passage I44 and through the slots I48 in the casing I46 into the passage around the burner where it mingles, with the atomized fuel and provides preheated oxygen for-combustion so that heatis rapidly generated in the combustion chamber 4. Radiant heat will thus be supplied to the water 'wall sections of the tubes 2 surrounding the combustion chamber and also some convection heat and the products of combustion will then pass into the flue 22 where they willtravel in heat exchange relation to the legs 20 and 30 of the steam; generator tubes 2 and also in heat-exchange relation to the superheater tubes 44 coiled about the combustion chamber but located in the flue 22. Radiant heat and convection heat will also be imparted to the tubes 66 forming the water wall at the rear end'of the combustion chamber and also to the tube I54 forming the water wall about the burner at the front end of the chamber. The water to supply these various tubes will be taken from the lower end of the separator 38 through the conduit 40 and delivered by the pump I2 through the conduit I0 to the header 8 and through the pipe 16 branching oil from the conduit I0 to the header 68, the pump I2 7 sure, with the aid of the nozzles I4, distribution to all the generating tubes connected with the respective headers. As hereinabove pointed out, the water input into the tubes is controlled by nozzles or ferrules I4 having openings I6 therein 7 the steam generating tube I54 joins the steam and water in the conduit 86 at the point I56 and thus also passes into the separator 88.

The separator herein illustrated is constructed to utilize both centrifugal and gravity forces in the separation of the steam from the water and comprises a lower compartment I58 into which extends a frustoconical structure I 66 open at its smaller lower end and provided on its inner wall with bafies I62 arranged to deflect the steam and water downward in a spiral path, the spiral increasing in pitch downward to compensate for reduction in the velocity of the mixture. The transverse section of the spiral may vary from top to bottom as shown. For example, the section may be flat and inclined at the upper end and may be inclined upwardly as shown further down to form troughs and may also be provided with lips I68 to increase the depth of the troughs.

It will be noted that the provision of a. concentrically-located inverted cone-shaped bafile-supportingmember provides space of increasing area from top to bottom between its outer surface and the inner surface of the wall of the compartment I58 of the separator casing 38. Into this space the water separated from the steam is discharged through holes I66 through the cone at or adjacent to the junction of the bafies with the cone, the holes preferably being of such size as to maintain a head of water in the bafile trough. Preferably more holes are provided in the lower troughs than in the. upper because of the increased accumulation of water.

To prevent any upward surge of water from the well at the lower part of the compartment I58 from entering the space within the cone I66,

a priming plate I'IO is locatedjust below the cone as shown.

Steam separated from the water in the lower part I56 of the separator casing, and usually still somewhat moist, will pass up into the secondary separator which may consist of a spiral pipe I72,

preferably of square cross section, which has a I. connection I73 with the compartment I58, as

shown, and serves to convey the vapor to the upper part of the chamber IM-of the secondary separator, the same spiral pipe H2 also preferably acting as a lguiding baflie to spiral the mois-,

ture separated 1 cm the steam in the secondary separator downwardly and out through the open ing I16 into a by pass I18 that conducts it back into the water well in the lower part of the compartment I58.

- the conduit 46 through which the superheated steam is taken to the turbine or other prime mover.

If it is found desirable to protect the superheater tubes, where they pass through the air jacket passage 96 to their connection with the steam pipe 46 to the prime mover, from loss of superheat to the cold air coming in through the. passage 86, a walled passage II'I may be provided through the walls 80 and 88 to exclude the air in the passage 96 from contact with the superheater tubes.

For the most part, provision has been made in the design of the parts for their expansion and particularly for the expansion of the generating and superheater tubes under the intense heats utilized in this generator, the bends in the generator tubes allowing for expansion without substantial displacement. The casing parts and the supporting elements are shielded from the high heats by water walls etc. and the limited expansions to which they are subjected are readily taken up by reason of their structural designs. The lowermost superheater support 52 is itself carried on floating supports and is unattached at its ends so that it is free to expand longitudinaltion comprising a bracket member I88 attached by screws to the end of each of the supports 88 and 60 and suspended from bolts or screws I'I9 threaded into a plate I8I connected by screws I62 to the ring 86, a space being provided between the head of each of the screws H9 and the bracket I86 for movement of the bracket lengthwise of the screws I18.

It will be noted thatthe generator tubes 2, including their legs 20 and 30, have substantial support against lateral displacement. For example, at their front ends the generator tubes 2 are connected to the water header 8, which is supported by brackets I36 from the ring 88 carried on the feet 92. Near the rear end of the combustion chamber a ring III, which may be spot weld-.

ed both to the water wall leg of the tube 2 and to the convection leg 28, or to either, is in turn supported by four coils I2 of the generator tubes 66,

these coilspeing directly supported by their connection to the steam and water header 32, which in turn restsupon the legs 14. In addition to this, I have the spacing and supporting ring I'IB which, being spot-welded to the legs 38 of the tube assembly, tends to maintain the lateralrelationship of the tubes to each other, the other ends of the legs 38 being directly connected to the water and steam header 82.

If, by reason of the length of the generator as a whole, additional means be required to maintain the lateral relationships of the generatingtubes 2 including their legs 26 and 30 this may be efiected by Dl'oviding spacing rings I86 and I86 spot-welded to the legs 20 and 38 respectively of the tubes 2.

In? asomewhat similar manner the spiral coils of the water wall tubes 66 at the rear end of the combustion chamber may be supported in proper relationship to each other by straps I88 radially arranged behind the water wall spirals and spot welded to each of the coils that they traverse. Preferably these straps will be arranged so that alternate straps are connected at their outer ends to the casing 62 and are left free at their inner ends while the other straps will be connected at their inner ends to the casing 62 and left free at their outer ends.

As hereinabove suggested. the steam and water header 32 is incomplete annulus in proper relation to each other and to the surrounding structure, the ends are preferably provided with laterally-extending ears I90, opposed to each other, through which bolts I92 extend to lock the parts in a predetermined relation to each other. A similar interruption is provided in the ring 86.

Whenever it is desired to withdraw the superheater assembly the superheater. tubes 44 are disconnected from the conduit 42 as, for example, 'by cutting them ofi with a hack saw, and are also disconnected from the steam conduit 46. The bolts I92 are then withdrawn from the ears I90 at the two ends of the incomplete annulus 32,

the rear end of the generator casing and the rear water wall having been removed, and the superheater assembly can then be withdrawn bodily from the structure without interference with the assembly of generator tubes,

It will be noted from Figure 2 of the drawings that the casing walls 94, 80 and 26 are each provided with slots to provide for the withdrawal of the straight sections of the superheater tubes, theseslotsbeing provided respectively with removable covers I94 and I96 and I88.

Each of the steam generator tubes 2, with its convection legs 20 and 30, it will be seen, lies approximately in a plane radial to the axis of the generator structure as a whole. It may, however, sometimes be desirable not to have all three legs of each generator tube exactly ina plane radial to the axis of the generatortas a whole. For example, it may be preferable to have the water wall legs of the tubes 20 staggered with respect to the water wall sections so that the cooling effect of the legs 20 will be exerted upon these portions of the casing 6 which lie between the water wall legs. L g

If closer spacing of the straight portions of the water wall legs of the generator tubes 2 is desired than would be possible with curves 28 of uniform radii of "curvaturejaltemate curves 28 may be of smaller radius ofcurvature than the'tubes adjacent thereto whereby a slight nestingpof'adjacent tubes may be permitted, thus allowing a closer spacing of the straight sections. I

Although the main supply of air for combustion will preferably come in through the openings I48 in the burner casing, it may be found desirable in some cases to provide secondary air for the completion of, the combustion. When this is found to be desirable, openings 100 and 202 may be provided respectively in the walls H4 and 62 which will permit air from the passage H2 to enter the rear end of the combustion chamber.

From the foregoing description of the construction and modeof operation of a steam generator embodying the present invention it will be apparent that theinvention facilitates the design and construction of a compact generator for producing high pressure, high temperature steam in substantial quantities.

Without attempting to go into detailed engineering calcu ations, it may be stated that a rough estimate of the dimensions of various parts of.'- a steam generator, having the general construction and arrangement of parts herein illustrated and described, which will have a capacity axis of the structure.

of at least 1000 H. P. on the prime mover, with a suflicient surplus to operate the auxiliaries such as the pump l2 and the fuel and air blowers, not

shown, and which will generate steam at 1000 pounds pressure and at about 1000 F. temperature, is the following:

The steam generating tubes 2, of A" O. D. and spaced about a cylindrical combustion space of a diameter of approximately 33" in a generator structure having an overall length of about 11 feet, would each be about 26 feet long, including the convection legs 20 and 30, which would give a substantial path of travel of the water in heatexchanging relation to the radiant and convection heat of the combustion chamber and also in heat-exchanging relation to the convection and radiant heat of the convection flue 22.

The superheater tubes 44, of approximately the same outside diameter as the generator tubes 2. would have an average length each of about 84 feet. The overall diameter of the structurewould be about 4' 6". The water header 8 would probably be about 3 inches 0. D. and the steam and water header 3 inches 0. D.

It will be understood that the foregoing figures are given merely forthe purpose of illustrating the relatively small overall dimensions and the re atively light weight of a steam generator of this capacity which is made possible by the improved design of the present invention and that there is no intention to confine the invention to the particular dimensions for the particular capacity referred to, the invention obviously permitting wide variations in the relative dimensions of theparts for the same capacities and also to meet particular conditions, particularly in automotive vehicles.

Although the generator herein illustrated and described is arranged with its main axis extending in a horizontal direction, the invention is not confined to such an arrangement of the main The method ofgenerating steam employed in this structure and described and cfaimed in United States Letters Ratent No.

884,979, granted October 25, 1932, permits the generating tubes to be arranged in substantially any manner, either vertically or inclined, or horizontally and spirally, as herein shown. It is therefore practicable to turn the illustrated generator up on end, for example, with its rear end at the bottom of the structure, the only fluid cn-.

fining structure change necessary, when this is done,-beirig to re-locate the steam and water separator 38 and the pump l2.

What is claimed as new is:

1. In a steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a surrounding flue, and water walls lining said combustion chamber and said flue and comprising steam generating tubes each of which extends over the lateral wall of the combustion chamber and over the two lateral walls of the flue.

2.In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindricalcombustion chamber and a flue surrounding and'substantially concentric with said combustion chamber and communicating therewith at one .end, and water walls lining said combustion chamber and said flue and comprising steam generating tubes each of which extends over the lateral wall of the combustion chamber and over the two lateral walls of the flue, said generating tubes being each loflue; an annular distributing header to which one end of each of said tubes is connected, and an annular collecting header to which the other end of each of said tubes is connected.

4. In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber and communicating therewith at one end, water walls in said combustion chamber and said flue and comprising steam generating tubes each of which extends over the'lateral wall of the combustion chamber and over the two lateral walls of the flue, an annular distributing header to which one end of each of said-tubes is connected, an annular collecting header to which the other "end of each of said tubes is connected, and av return connection between said headers including a steam and water separator and a circulating pump.

5. In a steam generator of the closed circuit positive circulation typ'e, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a surrounding flue communicating therewith at one end, water walls lining said combustion chamber and said flue, said walls comprising steani generating tubes forming parts of a closed circuit, means in said circuit for setting up a positive circulation of water through each of said generating tubes in an amount in excess of the conversion capacity thereof, and means for separating the steam produced in said circuit from the water before it is returned to the generating tubes, each of said combustion chamber tubes being so connected to two flue tubes as to provide for flow of water introduced into said three tubes only in series in a given order over said combustion chamber and flue walls.

6. In ;a steam generator of the closed circuit I positive circulation type, an enclosing casing so with said combustion chamber and communi- .zcating therewith at one end, water walls lining partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric the lateral wall of said combustion chamber and the lateral walls of said flue and comprising steam generating tubes each of which extends rearwardly over the lateral wall of the combustionchamber, forwardly over the inner wall of the flue and rearwardly over the outer wall of I the flue, an annular distributing header to which :the intake end of each of said tubes is connected, .located at the front of the structure, and an ,annular collecting, header to which the discharge end of each of said tubes is connected, located at the rear end of the structure.

7. In a. steam generator of the closed circuit positive circulation type, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber and communi-,

cating therewith at one end, water walls lining the lateral wall of said combustion chamber and the lateral walls of said flue and comprising steam generating tubes each of which extends rearwardly over the lateral wall of the combus- 8. In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber, water walls lining and protecting the cylindrical wall of said combustion chamber and theadjacent wall of said flue and comprising steam generating tubes each of which extends lengthwise of said combustion chamber and lengthwise of-said flue, an annular distributing header to which each of said generating tubes is connected at its intake end, an annular collecting header to which each of said tubes is connected at its discharge end, other water wall tubes shielding one end of said combustion chamber and discharging into said collecting header, and a distributing header for said last mentioned tubes.

, 9. In a steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a communicating flue around said chamber, steam generating tubes arranged about the combustion space in said chamber and so extended lengthwise of said combustion chamber'and into and along the two walls of said flue that they line and protect from excessive heat both the wall of the combustion chamber and the two walls of the flue, a water header with which one end of each of said tubes is connected, said headerforming -a loop of a contour similar to that of the'cross section of the combustion chamber, and a second header to which the other end of each of said tubes is connected, said second header having a contour similar to that of said flue.

10. In a steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a communicating flue alongside said combustion chamber and steam generating tubes each having at its intake end means for restricting the input of water thereinto, each of said tubes comprising three substantially parallel sections successively connected by bends, one section being exposed directly to the heat of the combustion chamber and the other two sections being located in said flue and exposed therein to the heat from the products of combustion, the direction of flow of the water through the section of the tube in the combustion chamber andthrough I section of the tube.

11. In a steam generator, anenclosing casing so partitioned interiorly as to provide combustion chamber and a flue surrounding said combustion combustion chamber and lengthwise of .the-flue,'

the leg of the steam generating tube within said flue being substantially parallel to the leg within the combustion chamber and the two legs being connected by a bend providing a loop 01' substam tial radius, and steam superheater .tubes located in said flue and coiled about said generating tube assembly.

, 12. In a steam generator, an enclosing casing ,so partitioned interiorly as to provide a combus-' tion chamber and a fine surrounding said combustion chamber and communicating therewith at one end, a water wall comprising steam generating tubes each of which extends lengthwise of said combustion chamber and lengthwise oi the flue, the leg of the steam generating tube within said flue being closelyradjacentto and substantially parallel to the leg within the combustion chamber and the two legs being connected by a bend providing a loop offset to the chamber side oi'the flue leg, and steam superheater tubes lochamber and the adjacent wall of said flue and comprising steam generating tubes each of which extends lengthwise 01' said combustion chamber and lengthwise of .said flue, a water distributing headeriorming a loop of a contour similarto that of the cross section of the combustion chamber and to which the intake end of each of said tubes is connected, a steam and water collecting header forming a loop of a' contour similar to that or the cross section of the flue and to which the discharge end of each of said tubes is connected, return connections between said headers including a steam and water separator and a circulating pump, and steam superheating tubes receiving the steam i'rom'said separator, located within said flue. and coiled about said combustion chamber and generating tubeassembly.

14. A steam generator comprising an enclosing ceasing so partitioned interiorly as to provide a combustion chamber and a surrounding flue,-

within said flue and embraced by said steam generator tubes. e

15. In a; steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a flue surrounding said combos-.- tion chamber and communicating therewith at one end,'steam generating tubes lining and proin said flue and separated from said flue walls by said steam generating tubes.

'16. In a steam generator, an enclosing easing so partitioned interiorly as to provide a combustion'chamber' and a communicating flue around said chamber, steamaenerating tubes arranged about the combustion space in said chamber and so extended lengthwise oi'said combustion chamber and into and lengthwise oi the two walls of the flue walls, steam superheater tubes located in the flue, coiled about the combustion chamber and separated from the walls of the flue by the steam generating tubes, a loop-like'water header to which one. end of each of said generating tubes is connected, and a second loop-like steam and water header to which the other end of each of said tubes is connected. x

17. In a steam generator, an enclosing casing so partitioned interiorly as toprovide a combustion chamber and a communicating flue around said chamber, steam generating tubes arranged about the combustion space in said chamber and so extended lengthwiseof said combustion chamber and into and lengthwise of the two walls 0! said flue as to line and protect the chamber and the flue walls, steam superheater tubes located in v the flue, coiled about the combustion chamber and separated from the walls of the flue by the steam generating tubes, a loop-like water header to which one end ofteach of said generating tubes is connected, and a second loop-like steam and water header to which the other end of each of said tubesvis connected, said last mentioned header having its loop interrupted to provide for bodily withdrawal of the steam superheater assembly.

18. In a steamgenerator, an enclosing casing so partitioned interiorly as to provide a substan= tially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber and communicating therewith at one end, water walls lining said combustion chamber and said flue and-comprising steam generating tubes each of which extends over the lateral wall of the combustion chamber and over the two lateral walls of the -ilue, steam superheater tubes coiled about the combustion chamber and: located in said flue between the,legs of the steam generating-tubes therein, whereby saidsuperheater coils may be removed bodily from the structure without dis- .turbingthe steam generating tube assembly.

19. In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber and communicating therewith at one end, water walls lining said combustion chamber and said flue and comprising steam generating tubes each or which ex- 7 tends over the lateral wall or the' combustion chamber and over the two lateral walls of the flue, steam superheater tubes coiled about the combustion chamber and located in said flue between the legs oi. the steam generating tubes therein, whereby said superheater coils may be emoved bodily'irom the structure without disturbing the steam generating tube assembly, an annular distributing header to which one end of each of said steam generating tubes is connected, an annular collectingheader to which the other end or, each of said steam generating tubes is connected, said last mentioned annulus having an inner diameter greater than that oi the superheater coils to permit the withdrawal of said coils "through the open center of said header.

20. Ina steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber, a water wall lining the cylindrical inside surface of said chamber and comprising tubes extending lengthwise or said chamber, a second water wall covering one end or said combustion chamber and com- '76 said flue as to line and protect the chamber and prising spiral tubes, intake headers for the tubes of the respective water walls and a common header into which all of said tubes discharge.

21. In a steam generator, an enclosing casing 50 partitioned interiorly as toprovide a cylindrical combustion chamber having a sheet metal wall stopping short of the rear end of the combustion space and a flue surrounding said combustion .chamber and having a sheet metal outer wall, a

sheet metal rear wall continuouswith said flue outer wall and provided with an annular concavity opposite the end of the combustion chamber wall, and steam generator tubes lining and protecting said combustion chamber wall, the two walls of said flue and said rear wall.

22. In a steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a flue surrounding said combustion chamber and communicating therewith at one end, all formed of sheet metal, individual continuous steam generating tubes each lining and protecting the wall of said combustion chamber and also the two walls of said flue, said partitions defining a second flue surrounding said first mentioned flue and communicating therewith at the end of said first mentioned flue remote from its communication with the combustion chamber, and air preheater tubes extending through said second flue.

23. In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and substantially concentric with said combustion chamber and communicating therewith at one end, all formed of sheet metal,

a water wall lining said combustion chamber and said flue and comprising steam generating tubes each of which extends over the lateral wall of.

to said second flue at the end thereof remote from its connection with the flrst'fiue.

24. In a steam generator, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion-chamber having its cylindrical wall stopping short of the rear end of the combustion space, a flue surrounding said combustion chamber and'having an outer wall "substantially concentric with said combustion chamber, and a rear wall continuous with said outer flue wall and provided with an annular concavity opposite the end of the combustion chamber wall constructed and arranged to facilitate substantially uniform distribution of the products of combustion to the flue and to reduce resistance to change of direction by maintaining a substantially constant velocity.

25. In a steam generator of the class described, an enclosing casing so partitioned interiorly as to provide, a substantially cylindrical combustion chamber and a water wall covering the rear end of said combustion chamber, said water wall com prising a plurality of spirally coiled steam generating tubes, said spirals lying one within the other whereby close-spaced shielding of the wall surfaces by the tube surfaces is provided without. too sharp bending of any individual tube, and a header, shielded by the central portion of said water wall, to which the inner ends of said spirals are connected.

, chamber, said partition also defining a second flue 26. In a steam generator of the closed circuit positive circulation type, the combination with an enclosing casing so partitioned interiorly as to provide a combustion chamber and a fuel burner comprising means for directing a mixture of air 5 and fuel into said combustion chamber, of a water wall comprising tubes extending lengthwise of said chamber and arranged about the combustion space therein, said partitions defining a flue surrounding said combustion chamber and communicating therewith at one end thereof, said tubes each also extending into said flue and over each wall thereof along the path of travel through said flue of the gases coming from said combustion 15 surrounding and communicating with said first mentioned flue at the end of said first mentioned flue remote from that connected with the combustion chamber, air preheater tubes communicating with said burner for preheating the air therefor and arranged in said second flue along the path of travel of the hot gases through said second flue, and an air jacket surrounding said second flue and providing an air intake flue communicating with said air preheater tubes at 25 one end thereof said'water wall so lining and protecting the combustion chamber wall and the two walls of said first-mentioned flue that said casings and said flues may .be formed of sheet metal without refractory lining.

F 27. In a steam generator, an enveloping casing so partitioned interiorly as to provide a combustion chamber and a flue surrounding said combustion chamber and communicating therewith at one end, and steam generating tubes lining and protecting the wall of said combustion chamber and the walls of said flue, each of said combustion chamber tubes being so connected to two flue tubes as to provide for flow of water introduced into said three tubes only in series in a given order over said combustion chamber and flue walls.

28. In a steam generator, an enveloping casing so partitioned interiorly as to provide a combustion chamber and a flue surrounding said combustion chamber and communicating therewith at one end, steam generating tubes lining and protecting the wall of said combustion chamber and the walls of said flue, each of said combustion chamber tubes being so connected to two flue tubes as to provide for flow of water introduced into said three tubes only in series in a given order over said combustion chamber and flue walls, and means for insuring distribution of the water to the steam generating tubes so as to insure said series flow of water through said three tubes.

29. A steam generator having, in combination, an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and an annular flue extending about and communicating with said combustion chamber, steam generating tubes extending lengthwise of said chamber and arranged about the combustion space therein, said tubes also extending into said flue and along thepath of travel through said flue of the gases leaving the combustion chamber, and steam superheater tubes coiled about the combustiomchamber and so located in said flue as to be positioned interiorly of the extent of some of said tubes in said fiue. 30. A steam generator comprising an envelop ing casing so partitioned interiorly as to provide a combustion chamber and a surrounding flue, and steam generating tubes lining and protecting 5' combustion chamber andlengthwise of said flue,

the wall of the combustion chamber and the walls of said flue, said tubes lining one wall of said flue being separated from those lining the other wall of the flue to leave a space for a heat exchanger within said flue unoccupied by said steam generating tubes.

31. A steam generator comprising an enveloping casing so partitioned interiorly as to provide a combustion chamber and a surrounding flue, steam generating tubes lining and protecting the wall of the combustion chamber and the walls of said flue, said tubes lining one wall of said flue being separated from those lining the other wall of the flue to leave a space for a heat exchanger within said flue, unoccupied by said steam generating tubes, and steam superheater tubes located in said space in said flue.

32. In a steam generator, an enclosing casing so partitioned interiorly as to provide a combustion chamber and a communicating flue around said combustion chamber, steam generating tubes arranged about the combustion space in said,

chamber and extending both lengthwise of said and steam superheater. tubes located in said flue and coiled about said combustion chamber but positioned interiorly with respect to at least some of said steam generating tubes located in said flue.

33. A steam generator having an enclosing casing so partitioned interiorly as to provide a substantially cylindrical combustion chamber and a flue surrounding and communicating with said combustion chamber at one end, a water wall surrounding the combustion space in said cham- 5 her and comprising tubes extending longitudinale 1y of said chamber, said water wall tubes being extended into said flue along the path of travel of the hot gases through said flue, and a rear wall having an annular concavity opposed to the partition between the combustion chamber and said flue.

34. A steam generator having an enclosing casing so partitioned in'teriorly as to provide a substantially cylindrical combustion chamber and a' flue surrounding and communicating with said combustion chamber at one end of the partition separating said flue from said combustion chamber, a water wall surrounding the combustionspace in said chamber and comprising tubes extending longitudinally of said chamber, said water wall tubes being extended into said flue along the path of travel of the hot'gases through said flue, a' rear wall having an annular concavity opposed to the partition between the combustion chamber and said flue, and a water wall covering said rear wall and conforming substantially to the surface contour thereof.

MORRIS CARROLL.

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