US2463901A - Locomotive with reciprocating engine receiving exhaust from steam turbine - Google Patents

Description

March 0, 1949. R. M. OSTERMANN LOCOMOTIVE WITH RECIPROGATING ENGINE RECEIVING EXHAUST FROM STEAM TURBINE 2 Sheets-Sheet 1 Filed Sept. 15, 1945 INVENTOIF. Puda/f Oszermann March 1949, R. M. OSTERMANN LOCOMOTIVE WITH RECIPROCATING ENGINE RECEIVING EXHAUST FROM STEAM TURBINE 2 Sheets-Sheet 2 Filed Sept. 15, 1945 Patented Mar. 8, 1949 LOCOMOTIVE WITH RECIPROCATING EN GINE RECEIVING EXHAUST FROM STEAM TURBINE Rudolf M. Ostermann, Evanston, Ill., assignor to Combustion Engineering-Superheater, Inc., a corporation of Delaware Application September 13, 1945, Serial No. 615,995

'1 Claims.

The present invention relates to steam locomotives and particularly to improvements in the arrangements for utilizing steam in the engines thereof,

When single expansion steam locomotives are equipped with boilers capable of producing more steam than the cylinders can efficiently use at relatively high boiler pressure, of say 250# pressure or more, the locomotive engines are normally operated with unusually long steam admission periods, thus obtaining an unusually large amount of power for train haulage. With the steam admission periods so lengthened, the expansion periods are of necessity decreased, and therewith the volume ratio of the steams expansion. Such operation results in producing the desired amount of excess power but in a very inefficient manner because the steam cannot be expanded to near atmospheric pressure as it should be for best efficiency. To change the design of a single expansion locomotive of a given boiler pressure so that it might produce more horse power with efiicient expansion would require increasing the size of the cylinders and therewith also the tractive force. However, in order to operate a locomotive without undue slipping of the wheels, the cylinder and piston diameters, which determine the tractive force, must be strictly limited to the ones with which the steam of boiler pressure does not produce a bigger piston thrust and a bigger tractive force than can be safely employed with the frictional adhesion of the locomotive wheels. For this reason, it is impractical to equip over-boilered reciprocating single expansion steam locomotives with cylinders large enough for an economical expansion of the steam.

However, it is possible according to my invention to modify the expansion ratio of a reciprocating single expansion locomotive and increase the efiiciency of its steam use under varying load conditions by utilizing a primary expansion steam turbine so combined with the cylinders of a locomotive engine that the latters full starting tractive effort is produced by the action of steam of boiler pressure against the pistons, while, as the locomotive speed increases, the steam pressure upon the pistons and the torque produced by the pistons upon the drivers are automatically decreased at any cutolf. At the same time the decreasing cylinder tractive effort is supplemented with a tractive effort developed by the turbine or turbines also coupled to the driving wheels of the locomotive. The steam on its way to the cylinders flows through a turbine or turbines and is partially expanded before some or all of it gets to the cylinders of the locomotive for final expan- S1011.

Such a compounding arrangement is to be distinguished from the arrangement in Ostermann and Williams U. S. Patent No. 2,102,806 which also combines a primary expansion turbine with a secondary expansion reciprocating engine jointly driving the axles of a locomotive but in which the tractive effort is manually regulated by altering only the cylinder cutoff, i. e., by manually altering, with it only, the mean effective piston pressure, with any given engine admission pressure. In that system automatic regulation, by throttling, of the pressure at which the operating steam is admitted to the primary expansion turbine s0 as to produce an engine admission pressure which does not unduly vary at any locomotive speed, is resorted to in order to leave the operator free to adjust the working cutofi of an oversized cylinder to the varying needs of the train propulsion without ever producing enough buildup of pressure against the pistons to slip the driving wheels, Clearly, slipping the drivers would be inevitable with this earlier system without some sort of automatic throttling of the primary steam pressure, and without thus limiting the cylinder admission pressure automatically.

While the arrangement described in this earlier patent, 2,102,806, is workable, it has the disadvantage that the throttling of the steam, before it enters the turbine, destroys part of the potential opportunity for primary adiabatic expansion in the latter. It therefore lowers the efliciency with which the internal energy of the steam that propels such a compounded locomotive, is transformed into mechanical energy. After further consideration and study of this general type of locomotive compounding arrangement, I have come to the conclusion that this disadvantage of the system as in Patent 2,102,806 can be avoided, and that a compound locomotive with a primary expansion turbine and a secondary expansion reciprocating engine is, without the need of any steam throttling, practical enough, provided the turbine is so designed that the total cross sectional area of its steam flow and of the steam impingement upon its vanes is made variable at will, as well as the cylinder cutoff, and that the turbine or turbines be compounded with cylinders which have pistons no larger than those which produce the requisite maximum tractive effort with full boiler pressure upon them.

In the drawings:

Figure 1 illustrates in elevation an application 3 of my compounding system to a single expansion two-cylinder steam locomotive;

Figure 2 is a corresponding diagrammatic front end view;

Figure 3 shows the partial development of a steam turbine with one of its controlling nozzles;

Figure 4 is a partial plan view of the turbine steam chest indicating how a multiplicity of controlling nozzles may be applied to the turbine, so as to vary the area of steam impingement;

Figure 5 is an enlarged view; on line 55 of Fig. 1, of a cab indicator provided for maintaining the proper relation between steam consumption of the turbine and the, cut-01f or expansion ratio of the reciprocating engine; and

Figure 6 is an elevational View similar to Fig. 1 illustrating an arrangement modified for an engine of higher steam pressure.

Referring to Figure l, steam from the boiler l, which is operated as customary. to maintain a constant steam pressure, passes to the superheater and the superheated steam flows from the header 3 through pipe 4 into a multiple valve chest 5 for theturbine. The valve cavities of chest 5 are connected with nozzles 6 (Fig. 3) in the steam chest of turbine l by pipes 80., b, c, and d. The turbine 1; exhausts itssteam into a pipe 9 connected with the steam chests ll! of the reciprocating engines ll. The piston. l3 of each engine ll reciprocates by the force of the pressure as the steam is admitted by the reciprocating valves 12 on alternate sides'of it, andthe steam is finally exhaustedfrom thecylinders through ports [4a, and I lb into an exhaust nozzle hlc in the usual manner of a reciprocating steam engine.

While. the pistons l3 revolve the main driving axle it of the locomotive by means of main rods It in the usual manner of a locomotive drive, the turbine 7 drives the same or another axle throughshaft 20, suitablereduction gearing 2i, shaft 22 and worm gear 23 and 2 4, in the same senseof rotation. The travel of the valves I2 is, as usual, lengthened or shortened by a cab lever 25 which connects to valve gear means I5 through levers and rods 25, 27 and 28, thus altering the valve cutoff in forwardmotion of the locomotive.

The turbine steamchest fpcontains a multiplicity of valvesv 5a opened and closed at will-by cams on a camshaft 5b,. which is rotatable by means of gears 25 and Bil-interposed in shafts 3| and 32, the latter carrying a handwheel 33 within the cab of the locomotive. By turning the handwheel or throttle 33 individual valves can be successively opened and closed, therebyincreasing or decreasing the totalturbine wheel area which is impinged upon by the steam on its way to the valves of the engine. in forward motion. When the cutoff lever 25 is in a position to the left of vertical in Fig. 1, the link blocks are in the upper half of links 15b, and the movements of the Valves l2 in relation to those of pistons it are altered in phase producing a reverse motion of the engine. During reverse motion all of the valves 5a are closed and steam is supplied to the engine directly from steam-pipe 4 by means of reversing throttle Mcontrolled by cab lever 35 through rods and levers 36, 3'! and 38, thus by-passing the turbine].

A gauge 39 is located in the sight of the engi-g neer, to ind icate the pressure of partially expanded steam within thepipe-Q to which it is connected by a pipe 40. Fulcrumed on the axis ofthe gauge pointer is a first class lever carrying a target 4! whose position is altered in conformance with changes in the position of cut-off lever 25, the two being mechanically interconnected as by an adjustable push and pull cable control 42. The gauge 39 has a scale 44 graduated to show steam pressures and alined therewith are graduations 45 representing the optimum cut-off at which the reciprocating steam engine should be operated for the various pressures existing in the turbine exhaust pipe 9. 01' stated difierently, the graduations of scale 44 represent the steam pressure that should be maintained in pipe 9 by regulation of turbine valves So. for the preferred cut-off for engine ll under various operating conditions. The target 4| and gauge39could be separately mounted but one of. them wouldthen preferably be provided with both scales 44; 45 or at least with the scale pertaining to the other indicator so that, for example, reference to target ll would indicate the proper pressure tonmaintain'for a particular cut-oft; or,viceversa, the gauge pointer 51 would;

indicate the proper cut-o-fi for the pressure maintained.

In Fig. 4 a partial plan view of the turbine steamchest isshown, and two of; the; flanges 50 of a 4-.nozzle turbine to whichconnect the pipes- 8a, 8b, 8c and M. which carry. the-steam tothe four nozzles 6 from the multiple valve;chest- 5., My.- invention is not limited tothe' use of any particular. number of nozzles, and Fig. 4 should be regarded as being; merely illustrative of a;

general arrangement.

The compounding arrangement above functions asv follows:

boiler pressurebuilds up in pi e Sl and a a nst the pistons l3 causingthe ppinterfil .of the gauge 39 to indicate. this full boiler pressure.

5! to the extreme left on thescale. ll when movedto the extreme. rightindicates maximum cutoff of the engine valves I2; locomotive speed increases; and-the: turbine ac, celerates, and increasingly. larger steam volumes are displaced by-thex-enginepistons, I3'in a unit of time, thepressure in pipe -9- drops; cause the steam volume demandzeventuallyexe.

oeeds the fixed steam discharge capacity ofthe;

turbine nozzles 6 to;which steam .flOWS .fromthe opened valves 50,. What steam does pass through the openednozzles, expands inythem below their throat, steam. pressure isconverted into steamv velocity, which latter is more and; moreccomepletely abstracted by the turbine: vanes, thereby:

producing a turbine torque which: assists the. reci-.

procating engines in turning. the drivers,. and

which torque increasesas the engine -torque;.de-

creases because of .thedrop' of pressureinzpipe; Q andagainst theengine pistons .13.- Thelocoe e may conceivably be. acceleratedwith lever :extreme forward position-.andwith all.

g-to the right as it indicatesflecreasing that thetarget points in; any position of: the-lever cri ed. The locomotive, is; started with the cab lever 25in the'forward posi-v tion; in this position the cutofi of the-valve I2 is the longest possible with the particular valvegear. design. Enough of the turbine valves 5a; are. opened by turning throttle handwheel33 to'gstartzthe train without slippingof the drivingwheels. Since the turbine 'i -is atrest in starting, the fu1l In Fig; 51 the gauge is assumedto -beso, constructedthat' full boiler pressuresin pipe 9 swings the pointer. Thetarget;

Asthe This is be Ives 5a open, until,the pointer 5 I- gradually pressure, stands oppositeqthe target24l.-; The.= mechanism .42 ,which. coordinates the;movement of; the, lever-25 andthe target .4! is adjustedisoi which is the minimum required inpipe. 9-1est the expansion in the steam in the cylinders be carried below apractical release pressure at the point at which the valves l2 open to the cylinder exhaust. On most locomotives the boiler capacity-is not suiificient to operate'with maximum cutoff at highest running speed and the piston displacement during steam admission has to be reduced'by shortening thevalve cutoif with lever 25 long before the maximum running speed is attained. This in turn moves the target 4|. to the left from its extreme right position. The engineer should then manipulate the handwheel 33 and adjust therewith the position of camshaft 5b and valves 5a so that the gauge pointer always coincides with the position of the target, or else remains to the left of it, thus making sure that atallspeeds and loads the boiler steam expands with as large an expansion ratio as possible down to release pressure which is still adequate for providing the proper boiler draft. In that manner th present compounding system produces the largest possible steam economy at all locomotive forward speeds and loads.

Inasmuch as steam locomotives in road service are operated in reverse only at very low speeds andthrough short distances, as in switching and making up trains, or when run without train, a separate reverse turbine may be readily omitted. When wishing to reverse the engine valves l2 are properly adjusted, all the turbine valves 5a are kept tightly closed and steam is admitted through opening the reversing throttle 34 with cab lever 35.

The system described above is efiective enough for'large powerful locomotives dealing with boiler pressure up to approximately 300 lbs.; it should be modified, however, for very much higher boiler pressures such as are being more and more advocated for highest possible fuel economy. As described, a regulable amount of steam is passed from the boiler and superheater first through a steam turbine and thereafter through a piston displacement engine. The quantity of steam which can be passed through the turbine is always limited by the displacement of the engine pistons during the period of steam admission to the engine, which is determined by the regulable valve cutoff. The maximum quantity of steam that can pass through the combination of turbine and conventional cylinder engine is dependent upon the diameter of the engine cylinder bore, upon the length of the piston stroke, upon the cutoff and-upon the distance which the pistons travel in the unit of time. The latter, 1. e., the piston speed as well as the piston stroke are definitely limited on locomotives for purely mechanical reasons. The valve cutoff must, at the maximum locomotive power development, occur early enough in the stroke so that the steam can fully expand in the cylinders to a pressure no higher than the one required to expel the steam properly and to produce the necessary draft. On the other hand, the cylinder diameter must always be so chosen as explained above, that full boiler pressure acting upon the pistons does not produce more tractive power at the rim of the driving wheels than ought to be produced, lest slipping of the drivers be experienced. This means that with'my compounding arrangement the bore of the engine cylinders would have to be reduced as the boiler pressure is increased, and that the cylinder volumes displaced by the pistons during the admission period would be concurrently decreased thereby limiting the steamthatcan be admitted to. the turbine without undulybuil'dingup theen gine admission pressure andrtherewith decreasing the economical maximum horsepower output of' the turbo-engine locomotive.

Locomotives driven by direct connectedsteam turbines, unaided by a steam fiow limiting displacement engine, havebeen built; but since thevelocity which the steam gathers during its-expansion in the turbine can only be abstracted with sufi'icient completeness by the turbine vanesat awell advanced speed of such a locomotive,

they are not eflicient'enough when'operated over awide-range of speeds. Since, on the other hand, the; economical steam generating capacity of modernlocomotive boilers can be easily increased beyondthe economical steam demand of atwo cylinder'displacement engine, I therefore propose to modify theabove described compoundin arrangement-when dealing with boiler pressures but is unable to pass through the engine withfullest expansion opportunity in its cylinders. The engine H exhausts through draft nozzle Mo into the stack Me. The fullyexpanded turbine steam thus leaves the turbine casing through pipe BI and exhausts through nozzle Md which is preferably concentric with nozzle Mo. However, such discharge to nozzle I 4d occurs onlyafter a favorable turbine or locomotive speed has been attained. As the steam which enters theengine' H' has tobe only partially expanded I- arrange to bleed it through a pipe 62 from the turb ne after it has passed through a part of the turbine expansion stages, whereas the balance of r the steam admittedltotheturbine passes through all of its stages to the draft nozzle of the locomotive, after a. valve 63 in the direct exhaust line 6! between turbine casing and draft nozzle has opened. The same effect could be obtained by providing twoseparate. turbines and 1 one engine, one turbine having fewer stages than the other: However, for the sake of greatest mechanical simplicity and smallest weight, my preference is to provide only one turbine and to bleed the steam required by the engine from one of its stages.

The valve 63 opening either manually or automatically in response to the attainment of a predetermined locomotive speed allows a part of thesteam admitted to the turbine to escape directly to the locomotive draft nozzle. Valve 63 may be manually opened and closed at the will of the engineer, or as shown in Fig. 6, may be automatically operated in response to the turbine speed, by equipping the valve with an oil pressure cylinder 84 having a spring-loaded piston Within itand to coupling a small oil pump 65 to the turbine shaft. The pump may be made to produce a pressure under the piston, which increases with rising speed, and which may be thus made to force the valve open upon the attainment of a predetermined speed. The oil pressure may also be utilized to indicate turbine speed on a gauge 69 in the cab.

With this arrangement when valve 63 is closed someof the turbine wheels have to rotate at an appreciable speed in an atmosphere of stagnant steam of considerable pressure for extended periods and overheating of the metal of the wheels Would result unless some cooling steam were at all times drawn from the main exhaust.

Referring now to Fig. 6, it is seen that the multiple valve chest A from which the steam is supplied through pipes 8A, 8B, 8C and 8D to the nozzles of the turbine 60 may be part of the superheater header 3A and be located with it in the smokebox of the locomotiveahead of the front flue sheet. A shaft or rod 56, with which the turbine steam supply valves may be successively opened or closed, is seen to protrude from the steam chest 5A and to be actuated with a cab lever 33A by means of a rod 32A. Pipe 62 through which steam is bled from the turbine 60 at near the center of the turbine casing, is led to steam chest ID of the engine cylinders ll. Steam for cooling the turbine wheels may be drawn through pipe 66 from the exhaust end of the turbine casing and utilized for the operation of auxiliaries while the valve 63 is closed; more cooling steam may be drawn off through a pipe 61 to the shell of a feed water heater 68 which latter discharges its condensate through a pipe 10 to the suction line of the feed water pump H or else directly into the tender tank.

Feed water may be made to pass through a second feed water heater 12 before it is discharged into the boiler through pipe 13 and boiler check 14 for the purpose of increasing the thermal efiiciency of the plant. The steam turbine 60 is preferably operated with the highest practical initial steam temperature, so that the steam bled from it for the operation of the engine may be more highly superheated than necessary for the most economical expansion of the steam in the engine cylinders and the economy may be improved by allowing the steam in pipe 62 to impart some of its heat to the feed water in the heater 12. The heat freed by lowerin the superheat of the steam before it enters the engine is thus returned to the boiler by virtue of an increased feed water temperature.

This application is a continuation in part of that filed in my name on January 11, 1945, under Ser. No. 572,402, now Patent No. 2,397,977.

What is claimed is:

1. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes; a secondary expansion piston displacement engine or engines equipped with cut-off means for varying the valve thereof travel and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a steam pipe connecting the superheater outlet of the locomotive to said turbine valves; and a pipe or pipes connecting the turbine with the valve chest or chests of the reciprocating engine or engines.

2. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for exhausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stages of the turbine; a secondary expansion piston displacement engine or engines equipped with cut-off means for varying the valve travel thereof and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a steam pipe connecting the superheater outlet to said turbine valves; a pipe or pipes connecting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a conduit connected with the said turbine outlet; a normally closed valve in said conduit; and means for opening said valve to permit discharge of steam that has passed through all stages of said turbine.

3. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for exhausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stages of the turbine; a secondary expansion piston displacement engine or engines equipped with cut-off means for varying the valve travel thereof and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a steam pipe connecting the superheater outlet to said turbine valves; a pipe or pipes connecting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a conduit connected with the said turbine outlet; a normally closed valve in said conduit; and means responsive to attainment of a predetermined speed by said turbine for automatically opening said valve to permit discharge of steam that has passed through all stages of said turbine.

4. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for exhausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stages of the turbine; a secondary expansion piston displacement engine or engines equipped steam pipe connecting the superheater outlet to.

said turbine valves; a pipe or pipes connecting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a drafting nozzle for the boiler connected With the exhaust of said engine; second nozzle surrounding and concentric with said drafting nozzle; a conduit connecting said turbine outlet with said second nozzle; a normally closed valve in said conduit; and means for opening said valve to permit exhaust of steam that has passed through all stages of said turbine to said second nozzle.

5. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at Will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for exhausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stages of the turbine; a secondary expansion piston displacement engine or engines equipped with cut-off means for varying the valve travel thereof and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a.

steam pipe connecting the superheater outlet to said turbine valves; a pipe or pipes connecting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a conduit connected with the said turbine outlet; a normally closed valve in said conduit; and means for opening said valve to permit discharge of steam that has passed through all stages of said turbine; and a feed water heater interposed in the pipe connecting said turbine and engine for abstracting some of the heat from the steam Withdrawn from the turbine prior to its admission to said engine.

6. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for eX hausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stage of the turbine; a secondary expansion piston displacement engine or engines equipped with cut-off means for varying the valve travel thereof and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a steam pipe connecting the superheater outlet to said turbine valves; a pipe or pipes con necting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a conduit connected with the said turbine outlet; a normally closed valve in said conduit; and means for opening said Valve to permit discharge of steam that has passed through all stages of said turbine; and a heat exchanger interposed in the pipe connecting said turbine and engine for abstracting some of the heat from the steam withdrawn from the turbine prior to its admission to said engine.

7. In a power plant having a boiler providing superheated steam at constant pressure; a primary expansion steam turbine provided with multiple valve means for varying at will the areas of passage of unthrottled superheated steam through its vanes and having an outlet for exhausting the operating steam passing through all the expansion stages of the turbine; a bleed port for exhausting steam from one of the intermediate stages of the turbine; a secondary expansion piston displacement engine or engines equipped with cut-01f means for varying the valve travel thereof and thereby controlling the expansion ratio within the cylinder or cylinders thereof; a steam pipe connecting the superheater outlet to said turbine valves; a pipe or pipes conmeeting the turbine bleed port with the valve chest or chests of the reciprocating engine or engines; a conduit connected with the said turbine outlet; a normally closed Valve in said conduit; and means for opening said valve to permit discharge of steam that has passed through all stages of said turbine; and means for continuously withdrawing some steam from said turbine at a point near said exhaust outlet.

RUDOLF M. OSTERMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,102,806 Ostermann et a1. Dec. 21, 1937 2,274,395 Badenhausen Feb. 24, 1942

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