US2066151A

US2066151A - Reciprocating steam engine

Info

Publication number: US2066151A
Application number: US735313A
Authority: US
Inventors: Johansson Johan Erik
Original assignee: Goetaverken AB
Current assignee: Goetaverken AB
Priority date: 1930-01-16
Filing date: 1934-07-16
Publication date: 1936-12-29
Anticipated expiration: 1953-12-29

Description

Dec. 29, 1936.

J. E. JOHANSSON RECIPROCATINT STEAM ENGINE 3 Sheets-Sheet 1 Filed July 16, 1934 4, w a /O L 4/ Wm W 1 LL 6 w v g g f 0 a a. r a

- CONDENSER INVENTOR M J w ATTORNEY Dec. 29, 1936. J JOHANSSON 2,066,151

RECIPROCATING STEAM ENGINE Filed July 16, 1934 3 Sheets-Sheet 2 INVENTOR ATTORNEY Dec. 29, 1936. J, E, JOHANSSON 2,066,151

RECIPROCATING STEAM ENG INE Filed July 16, 1934 3 Sheets-Sheet 3 I' "IIK IIII" I 365 5 nu/Mg:

EPARATO A h h A #4 INVENTOR 02 M ATTORNEY Patented Dec. 29, 1936 UNITED STATES OFFICE RECIPROCATING STEAM ENGINE Johan Erik Johansson, Gothenburg, Sweden, assignor to Aktiebolaget Gotaverken, Gothenburg, Sweden, a corporation of Sweden Application July 16, 1934, Serial No. 735,313

In Sweden January 16, 1930 22 Claims. (Cl. 60-21) This application is a continuing application the steam between expansion stages and also in embodying the subject matter of and replacing some instances to compress it, but all of the methmy copending applications Serial No. 516,319 filed ods heretofore proposed involve one or more seri- February 1'7, 1931 and Serial No. 6%,770 filed ous disadvantages that either introduce losses November 2, 1932, andis to be considered as relatwhich reduce the net gain to a degree making ing back to said copending applications for all them impractical or involve so large a capital dates and rights. incident to the filing thereof, and expenditure for apparatus that in many cases the filing of foreign applications corresponding they are not economically justified. thereto. Considered in its broader aspects, the present 10 The present invention relates to reciprocating invention has for a general object the improve in steam engines and has particular reference to ment in the economy of multiple expansion re reciprocating steam engines of the multiple exciprocating steam engines by the employment of pansion type. Still more particularly, the invena novel method of treatment of the steam whereby tion relates to marine steam engines of the above steam which has been partially expanded in an type. engine is withdrawn therefrom and reheated by 15 It is a well known fact, established by both thea mechanical agency which may also impart adoretical considerations and practical operating ditional pressure, after which the steam is reresults, that the thermal efiiciency of a given turned to the engine for further expansion steam engine is greater if superheated steam is through a lower pressure range than that through expanded from a given initial pressure to a given which it was expanded prior to its withdrawal 20 exhaust pressure than if saturated steam is exfrom the engine. panded through the same pressure range. In A further object is the improvement of the addition to this, however, the increase in the economy of an engine of the kind described by operating economy of the engine actually obexpanding the steam to a lower pressure than is tained by the use of superheated steam is subpractically possible in a reciprocating engine and 25 stantially larger than that which can be acutilizing the additional energy thus obtained, counted for due to the increased theoretical therwhich would otherwise be lost, to effect reheating mal efliciency. This additional increase in econof the steam by mechanical agency as mentioned omy is obtained because the engine, when working above.

with superheated steam, utilizes the available A still further object of the invention is the 30 heat drop of the steam more efiiciently than when provision of relatively simple and inexpensive Working with saturated steam. apparatus for carrying the foregoing and other F om the f e oing it follows that it is deSir objects into effect which is of a nature such that ab e o mpl y superheated steam to as great an it may be applied readily to existing engines withe t s possible and t is Common practice to out either complicating the controls thereof or 35 s p y s pe eat Steam to the high pressure necessitating the provision of automatic interinlet of e s o th d to Which e Present locks, releases or the like in order to permit reinvention relates. Practical considerations, howverging of th engine, ever, limit the amount Of superheat that can In order to carry my invention into effect, I

be added to the steam before initial expansion, provide pump, hi h i advantageously i the 40 and as a result, t e temperature of the p form of a rotary compressor, to the inlet of which heated steam as Ordinarily Supplied multiple partially expanded steam withdrawn from an p nsion n ne drop to s i n mperaengine receiver at intermediate pressure is detll e g befOre eXpanSiOn 0f the Steam in the livered. If the steam as delivered to the pump eng is c p t d. Thus, substantially all u is wet, the moisture is preferably removed by a 4-5 t ple eXp superheated Steam engines p separator or the like before the steam is com- W respect to One more low Pressure pressed in the pump, so that the heat incident to a r intermediate pressure Cylinders, on wet the compression will appear in the form of supersaturated steam, and with respect to such cylinh t, d a higher economy of the process 111 ders the advantages to be derived from the use of be t i d, Th energy represented by th 50 superheated Steam are not Securedpower input to the pump is transferred to the In order t in the economy 0f Such steam in the form of superheat and additional gines by increas g the expansion range through pressure and the steam having the additional which the steam in the engine remains super energy i turned to the e gine by the p m for 55, heated it has heretofore been proposed to reheat further exp n n a ylinder Working in a lower pressure range than the cylinder or cylinders in which the steam was expanded before withdrawal to the pump. A highly efficient compressor or pump is not essential, since if radiation losses are disregarded, which losses are kept at a minimum by suitably insulating the pump and steam conduits, substantially all of the energy input to the pump is converted into additional heat and pressure in the steam as delivered from the pump. In some instances it may be desirable to impart to the steam a relatively small increase in pressure and. a relatively large amount of superheat, in which case a compressor of relatively low eificiency may be used deliberately. Also, the relative amounts of added superheat and pressure in the steam as returned to the engine may be determined by passing the steam through a suitable throttling or pressure reducing device which may convert a part or When the engine to which the invention is applied has more than two expansion stages, a plurality of pumps may be employed forwithdrawing steam from diiferent receivers and returning reheated steam to the engine, and in cases where it'is expedient, heat in addition to that added mechanically maybe added through the'medium of a superheater. y

,In order to secure the power necessary to drive the pump or pumps by the aid of which the steam isreheated, I employ an exhaust steam turbine which expands the steam to a much lower final pressure than that'to which it can be expanded in a reciprocating engine cylinder and which therefore increases the useful heat drop available in steam of given initial pressure and temperature. Not only does this increase in the available heat drop represent a potential increase in the economyof the power plant as a whole, as comparedwith the reciprocating engine alone, but the manner in which the additional energy that is made available'by the turbine is employed serves to increase the efiiciency with which the reciprocating engineI makes useof that portion of the total heat drop that, occurs in the reciprocating engine. p

Fora better understanding of the detailed nature of the invention and of the'several ways in which it may be applied advantageously in practice, I have illustrated, by way of example, in the accompanying drawings forming a part of this specification, several forms of apparatus other arrangement of apparatus embodying the invention;

Fig. 5 is a view similar to Fig. 1, showing still another arrangement of apparatus embodying the invention;

Fig. 6 is a top plan view of an engine similar to the engine shown in Fig. 1, provided with apparatus embodying the invention, and showing such apparatus arranged in the manner in which it has been installed in actual practice;

Fig. '7 is a vertical central section of the turbocompressor unit shown in Fig. 6; and

Fig. 8 is a section showing in a modified arrangement part of the engine structure shown in Fig. 1. n

Referring now more particularly to Figs. 1 and 2, I have shown more or less diagrammatically the application of the invention to a three-cylinder triple expansion reciprocating engine of an ordinary known kind. The engine comprises a high pressure cylinder l0, an intermediate pressure cylinder l2 and a low pressure cylinder l4 arranged for serial expansion bf steam therethrough in the order named. Admission to and exhaust of steam from the high pressure cylinder ill is controlled by a slide valve 16 of the piston type which admits steam to the cylinder from the high pressure steam chest I8 through the

channels

20 and 22, and which connects these channels with the intermediate pressure receiver indicated generally at for exhausting steam from the high pressure cylinder to this receiver. Receiver 24 is divided by means of a partition 26 into-a space 24a and a space 24b, and a valve 28 is provided opening toward the space 241) to permit flow of steam directly from space 24a to space 241) when the pressure in the former space exceeds that in the latter. The space 2411 provides an exhaust chamber for the high pressure cylinder, and the space 24b provides an inlet chamber or steam chest for the intermediate pressure cylinder I2. Admissionof steam to and exhaust of steam from cylinder I2 is controlled by the slide valve 30, which serves to admit steam from the space 24b to the

steam passages

32 and 34 and to exhaust steam from the cylinder through these passages to a second receiver indicated generally at 36 by way of the central exhaust passage 38. The receiver 36 comprises passages 40 when the pressure inthe former space exceeds the pressure in the latter. The space 36b pro vides a steam chest for the low pressure cylinder l4 and the admission of steam to and exhaust of steam from the low pressure cylinder is controlled by the slide valve 46 which acts to admit steam to the

cylinder passages

48 and 50, and which also serves to exhaust steam from these passages by way of the exhaust steam space 52 to the exhaust steam pipe 54 leading fromthe engine.

The inlet of a power driven pump 56 which is preferably in the form of a. rotary compressor is connected by means of a conduit 58 to the space 24a of receiver 24, and the outlet of thepurnp is connected by means of conduit 60 to the space 24b of this receiver. A throttling device 62, preferably in the form of a pressure reducing valve, is located in conduit 60.

I The inlet of a second pump 64 is connected by conduit 66 to the receiver space 36a of receiver 36, and the outlet of the pump is connected by means of conduit 68 to the receiver space 36b of this receiver. A throttling device 10 is located in conduit 68. The

throttling devices

62 and 10. are preferably located in the respective conduits adjacent to the discharge ends thereof.

An exhaust steam turbine, indicated at 12, is.

connected to

pumps

56 and 64 as by shaft 14 and serves to drive these pumps. The turbine is operated by exhaust steam supplied thereto through the exhaust steam conduit 54 and the steam, be-

fore being admitted to the blading of the turbine,

is preferably dried as by aseparator indicated generally at 16, which may be of any suitable form. The water removed from the exhaust steam is conducted from the separator through a suitable pipe 18 and may advantageously be used for any suitable purpose.

The steam exhausted from turbine 12 is conducted through conduit 80 to the usual condenser 82, in which the steam is condensed by Water supplied and removed through the usual circulating

devices

84 and 86. Since the turbine is capable of usefully expanding the steam to a very low absolute pressure, the condenser is advantageous- 13' Provided with a vacuum pump 88 in the usual manner for removing air and other non-condensible gases, and maintaining in the condenser a high degree of vacuum. The exhaust steam pipe 54 is advantageously connected to the condenser by means of a by-pass conduit 90, in which is located a control valve 92. V I

It will, of course, be understood that the several steam conducting conduits, the pumps and turblue, as well as the engine itself, are suitably lagged with heat insulating material in the usual way to reduce the radiation losses to a minimum. Portions of such lagging are indicated diagrammatically at 93 in Fig. 1. For the sake of clarity in the drawings, only small sections have been shown in this figure and omitted from the remaining figures.

High pressure steam is admitted to the steam chest l6 through the supply pipe 94, and in describing the operation of this embodiment of the invention it will be assumed that the steam sup.- plied through pipe 94 is superheated steamhaving a sumcient amount of superheat so that the steam, as exhausted to the receiver space 24a, still contains some degree of superheat, or is at least dry saturated steam.

Assuming the engine to be in operation with the turbine 12 being driven by exhaust steam from the reciprocating engine andin

turn driving pumps

56 and 64, the steam from the receiver space 24a is drawn into the pump 56 through conduit 58 and there is heated and compressed. The reheated steam from pump 56 is returned through conduit 60 to the receiver space 2 41), from which space it is admitted to the intermediate pressure cylinder for further expansion. The steam expanded in the intermediate pressure cylinder and exhausted to the space 36a is conducted, through conduit 66 to the inlet of the pump 64, in which the steam is again heated and compressed and delivered through conduit 68 to the receiver space 361) for further expansion in the low pressure cylinder M;

The increase in the amount of pressure of the steam due to the action of the pumps 56 and 64v must reappear in the form of either additional pressure or heat energy in the steam, or both.

vIf the pump is inefficient and a substantial amount of internal friction is produced in the steam during compression, the heat developed by this friction will be absorbed by the steam itself and its temperature will be raised accordingly. Friction due to flow through the conduits also tends to raise the steam temperature. Since we have assumed that the steam in conduit 58 is dry saturated steam or steam having some superheat, the additional heat imparted to the steam will be in the form of heat or superheat.

It will readily be apparent that apparatusof the kind just described is. of a nature such that the invention can easily be applied to an existing engine, and one of the advantages of the inven-. tion is that the benefits of it may be obtained without unduly increasing the pressure of the reheated steam to be expanded in a given part of the engine. The amount of pressure increase in the steam as it is returned to the receiver space 24b as compared'with the pressure at which the steam is exhausted from the high pressure cylinder to space 2411 can be determined by the use of a throttling device such as that indicated at 62. If the compressor is highly efficient and discharges the steam to conduit 60 at a higher pressure than is desired for admission to cylinder I2, the pressure may be reduced by means of the throttling valve 62 without loss, since the throttling device, in-reducing the pressure of the steam, increases its temperature in a well known manner.

It is evident that if it is desired the work of the pump 56 may be converted substantially entirely into added temperature in the steam by using the throttling device 62 to reduce the steam in conduit 60 to substantially the same pressure as that at which steam is admitted to the receiver or by constructing the pump with .so. low an operating efliciency that its output is transferred into heat absorbed by the steam. In the latter case, the use of the partition 26 and

valves

62 and 28 is not necessary, as shown by the modified arrangement in Fig. 8.

With the inlet of conduit 58 .and the outlet of conduit 66 located in the manner indicated, the

steam will tend to flow from the receiver to the pump and from the outlet of the conduit 60 to the intermediate pressure valve 30 in the manner described, even without the partition for separating the receiver into two diiferent spaces, provided the steam is not returned to the receiver at a pressure materially above that at which it is withdrawn.

If, as has been assumed, the high pressure steam supplied through pipe 94 is superheated, so that the steam exhausted from the high pressure cylinder contains some superheat, the amount of additional superheat added mechanically by the pump 56 and the throttling device 62, particularly when the latter is adjusted to convert most of the additional pressure into heat, may enable the steam to expand in the intermediate pressure cylinder while retaining some superheat as exhausted from this cylinder. The dry steam exhausted from cylinder l2 to the receiver space 36a is then compressed in pump 64 and returned to the receiver space 361) for further expansion in the low pressure cylinder l4. As in the case of the compression of the steam between the high and intermediate pressure cylinders, the compression of the steam be tween the intermediate and low pressure cylinders may be controlled so that the desired relative proportions of additionalitemperature and ell pressure may be obtained in the steam as delivered to the receiver space 36b.

The by-pass conduit 90 under the control of valve 92 permits the engine to be operated without intermediate reheating or compression of the steam, since if. valve02 is opened steam can flow directly to the condenser, thus stopping the turbine I2 and the

pumps

56 and 64. When this occurs, valves 28 and 44 open due to the difference in pressure between the difierent receiver'spaces, and steam flows through the receivers in the usual manner. The valves 28 and 44 may be opened and closed under the influence of the ditierence in pressures existing in the several receiver spaces or they may be manually controlled. To this end they may be provided with any suit able form of external control members, as diagrammatically indicated at 20a and 44a in Fig. 3.

In'addition' to adding superheat mechanically, superh'eat may also be added in certain instances by means of superheaters of the heat exchange or thermal type, and in Fig. 4 I have illustrated an embodiment of the invention in which superheatis added thermally as well as mechanically. In the apparatus shown in Fig. 4, the construction of the engine is the same as that shown in Figs. 1 and 2, with like parts designated by like reference characters, and need not be again described in detail. Further, the engine to which this form of the invention is in this instance applied, is shown as being operated by steam which is initially superheated. To this end the boilers indicated at 96 are provided with superheaters indicated generally at 90, to which saturated steam from the boilers is delivered through conduits I and from which superheated steam is delivered to the high pressure steam chest of the engine through conduit 94. The arrangement of the exhaust steam turbine, pumps and condenser is the same as that shown inFig. 1, but in this instance the

conduits

60 and 60. insteadof delivering the steam from the

pumps

56 and 64 directly to the receiver spaces 24b and 36b respectively, are connected respectively to the inlet headers I02 and I04 of the superheaters I06 and I08 located in the uptake flue connected to the boilers by the usual breeching indicated at I I0. The outlet headers I I2 and I I4 of the superheaters are connected respectively by

conduits

60a and 68a to the receiver spaces 24b..and 35b, and throttling valves 62 and I0 are recovery of additional energy of the exhaust steam from the engine, steam at intermediate pressures I can be withdrawn from the engine, reheated and returned thereto for further expansion without loss of pressure and even with increase of pressure, if desired. It will immediately be evident that the additional energy of the exhaust steam which is recoveredthrough the medium of the exhaust steam turbine is usefully returned irre-,

spective of whether additional thermal superheaters such-as are illustrated in Fig. 4 are employed or not, and that in. either case the recovered energy is returned in a form, such that the economy of operation of "the reciprocating engine is enshown in Fig. 1. In this form the valves I I6 are of the poppet type and are seated by springs II8 adapted to normally'maintain the valves closed, but which permit the valves to vopenwhen the pressure in chamber 24a exceeds that in 24b by a predetermined amount. Likewise. poppet valves I closed by springs I22 control flow of steam through the passages 40'and 4011. It will be evident that the use of either or the types of valves illustrated is optional in any of the embodiments herein described. The present embodiment of apparatus is adapted for use with an engine which is initially supplied eitherwith saturated'st'eam or with steam superheated to such a low degree that the steam as exhausted to the receiver space 24a is wet saturated steam. It is important to the securing of the desired results that the energy imparted by the pump to the steam withdrawn from the receiver is imparted in the form of added temperature and/or pressure, and is. not utilized ior the evaporation of the moisture content of wet steam admitted to the pump. To this end, the separator I24 is interposed between the receiver space 24a and the inlet of the pump 56 for n insuring admission to the pump of dry steam. A second separator I28 is shown in the inlet conduit'66 leading to the pump 64, this separator being supplied with a suitable drain pipe I30. Since the steam from which the water is separated in both separator I24 and separator I20 is at a pressure considerably above atmospheric, it

will be evident that the water outlets from the separators must be suitably trapped in known manner to prevent loss of steam through the water drains. Such traps for drains I26 and I30 arev indicated diagrammatically at I21 and I3I respectively.

Except for the provision ofseparators I24 and I28 for'insuring the delivery to the pumps of dry steam, the apparatusshown in Fig. 5 operates in the manner already described in connection with Fig. land is susceptible to thesame variations with respect to the relative amounts of added pressure and superheatsupplied tothe steam by the aid of the pumps. Itwill also be apparent that in case the desired operating temperatures and pressures of the steam in an installation such as that shown in Fig. 4 are such that there is any possibility of wet steam being delivered to the pumps, separators such as those shown at I24 and I28 may be employed. In this connection, it is pointed out that in general the use of separating means for insuring the supply of dry steam to the pumps is to be preferred. in all cases, since even' when steam withdrawn from a receiver will OOH- illustration 1 have shown apparatus for withdrawing'and reheating steam between each two adjacent stages of a triple expansion engine, the employment of reheating between more than one set of adjacent stages is optional, and that the invention is equally applicable to compound and quadruple expansion engines, and the number of times that the steam is withdrawn and reheated during its expansion in any given engine is a factor determined by the particular steam conditions and operating characteristics of the particular engine to which the invention is applied.

Turning now to Fig. 6, I have illustrated a form of apparatus embodying the invention which I have applied commercially to existing marine engines with highly satisfactory results. In this embodiment the engine is shown in top elevation, the high, intermediate and low pressure cylinders being indicated at II], I2 and I4 respectively. In this instance the steam is compressed and reheated only between the high pressure and intermediate pressure cylinders and is withdrawn from the high pressure receiver space 24a through conduit 58 to the compressor end of a turbo-compressor unit I32, which combines in a single unit the exhaust steam turbine 12 and the pump device 56. The turbo-compressor unit is advantageously mounted as shown di- I rectly on the condenser 82 and the compressed and reheated steam is delivered from the pump end of the turbo-compressor to the receiver space 2417 through conduit 60. "The turbo-compressor is supplied with steam through the exhaust steam conduit 54 in which is located the separator I6 and a by-pass conduit 96 with valve 92 is advantageously provided to permit direct exhaust of steam from the engine to the condenser. C'onduits 58 and SI! are preferably provided with valves I34 and I36 respectively, and the latter valve may, if desired, be employed as a throttling device. The turbo-compressor shown in Fig. 6 is illustrated on enlarged scale in section in Fig. '7. and advantageously comprises a turbine wheel i233 mounted on a shaft I40 which also carries the rotor I42 of a rotary or centrifugal compressor, to the inlet of which steam is admitted through conduit 58. The separator I24 is shown partially in section and may advantageously be of the type provided with a plurality of spirally arranged vanes I28 for causing separation of the Water from the steam due to centrifugal action. The specific form of the separator is not important to the invention, and any suitable type of steam drying arrangement may be employed. For example, the first stage of the compressor may be arranged to act as a tangential dryer, the moisture removed from the steam being discharged through the drain I44. Such tangential dryer may be used in addition to a separate dryer such as that indicated at I24 to insure as complete a separation as possible of entrained moisture from the steam.

From a consideration of Fig. 6 it will be evident that the invention provides simple and practical means whereby the efficiency of an existing marine engine installation may be substantially increased. As will be observed from this figure, the amount of engine room floor space required for the engine after the apparatus necessary to carry the invention into effect is installed is substantially no greater than for the reciprocating engine alone. The turbo-compressor unit is a relatively small and compact device which may be in substantially all cases readily installed as shown on top of the existing condenser, and the weight of the unit is such that comparatively little strengthening of the condenser top is required in order to support the weight of the unit. Since there is no mechanical connection between the moving parts of the turbo-compressor unit and the reciprocatingengine, the turbo-compressor unit may be of the high speed type, and consequently of relatively light weight for a given power. Furthermore, the mechanical independence of the turbo-compressor unit with respect to the reciprocating engine makes possible the operation thereof at varying speeds with respect to the speed of operation of the reciprocating engine. Consequently, no manual control or automatic control devices are required for the compressor equipment order to take care of the variations in operation conditions occasioned by operation of the reciprocating engine at varying speeds or in reverse direction.

The compact arrangement that is possible with the present invention results in a minimum amount of external steam piping, and consequently losses due to radiation of heat are maintained at a minimum and the cost of the installation is also made relatively low.

In applying the invention to an existing engine the structural changes necessary to the engine itself are relatively few and simple, consisting usually only of the insertion of the partition or partitions and valves advantageously employed to divide one or more of the. receivers of the engine into separate steam spaces. In case of engines of the kind in which the receivers are in the form of pipes external of the main engine cylinder castings, the conversion of an engine to operation in accordance with the invention is more readily accomplished than is the case with engines of'the kind illustrated having internal receivers.

Another important advantage of the invention in connection with its applicability to existing engines is the fact that the benefits of the invention are not dependent upon increasing to a great extent the pressure of the steam in the reheating process. Consequently, the invention may be employed with existing engines without danger of over-stressing the engine parts and. without having to substantially reconstruct the engine in order to permit it to operate safely.

From the foregoing description it will be evident that the invention may be applied in many diiferent specific ways, and it is accordingly to be understood that the invention embraces all variations in the form of apparatus and the mode of operation that may fall within the scope of the appended claims. It is further to be understood that certain features of the invention may in some instances be employed to the exclusion of others.

What I claim is:

1. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a condenser, a low pressure turbine receiving steam from a low pressure cylinder of the engine and exhausting steam to said condenser, a pump driven by said turbine, a con duit for conducting at least the major portion of the steam exhausted from one of said cylinders to the suction side of the pump, and a conduit for conducting steam from the discharge side of the pump to the means for admitting steam to the cylinder next in the series after the cylinder exhausting the steam conducted to the pump.

2. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a condenser, a low pressure turbine receiving steam from a low pressure cylinder of the engine and exhausting steam to said condenser, andmeansfor returning energy derived from said turbine to steam partially expanded in said engine comprising a pump driven by said turbine, a conduit for conducting at least the major portion of the steam exhausted from one of said cylinders to the suction side of said pump, and a conduit for conducting steam from the discharge side of the pump to the means for admittingsteam to'the cylinder next in the series after: the cylinder exhausting the steam conducted to the pump, the last mentioned means being constructed to impart to the steam in the form of heat of 'superheat a substantial portion of the energy derived from the turbine.

3. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein including a high pressure cylinder, means for admitting steam to and exhausting steam from each of said cylina'pump driven by said turbine, a conduit for conducting at least the major portion of the steam exhausted fromsaid high pressure cylinder to the suction side of the pump and a conduit for conducting steam from the discharge side of the pump to the means for admitting steam to the cylinder next inthe series after the high pressure cylinder.

4. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein and a receiver between two cylinders adjacent in the series, said receiver being divided to provide a first receiver space for receiving steam exhausted from one of said cylinders and a second receiver space adapted to supply steam to another of said cylinders for further expansion therein, a compressor, means for driving the compressor, a conduit for conducting steam fromsaid first receiver space to the compressor, a conduit for conducting steam from the compressor to said second receiver space, and valve means providing for direct fiow of steam from said first receiver space to said second receiver space when the pressure in the first receiver space exceeds the pressure in the second receiver space.

5.-Ina steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein anda receiver between two cylinders adjacent in the series, said receiver being divided to provide a first receiver space for receiving steam exhausted from one of said cylinders and a second receiver space adapted to supply steam to another of said cylinders for further expansion therein, a compressor,

serial expansion of steam therein and areceiver, a partition for dividing said receiver into a first receiver space for receiving steam exhausted from one of said cylinders and a second receiver space adapted to supply steam to another of said cylinders for further expansion therein, a compressor, means for driving the compressor, a conduit for conducting steam from said first receiver space to the compressor, a conduit for conducting steam from the compressor to said sec- 0nd receiver space, and spring loaded valve means associated with said partition for automatically permitting direct flow of steam from said first receiver space to said second receiver space when the pressure in the first receiver space exceeds the pressure in the second receiver space by a predetermined amount.

7. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein,means for admitting steam to'and exhausting steam from each of said cylinders, a condenser, a low pressure turbine receiving steam from a low pressure cylinder of the engine and exhausting steam to said condenser, and means for heating steam partially expanded in said engine comprising a pump driven by said turbine, a conduit for conducting steam exhausted from one of said cylinders to the suction side-of said pump, a conduit for conducting steam from the discharge side of the pump to the means for admitting steam to the cylinder next in the series after the cylinder exhausting the steam conducted to the pump, and throttling means on the discharge side of the pump for reducing the pressure and increasing the heat of superheat of the steam delivered by the pump.

8. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein, a turbine forexpanding steam finally exhausted from the en gine to a pressure below that to which it can be expanded in the engine, and means for withdrawing substantially all of the steam exhausted from one of said cylinders in partially expanded state and returning it to the engine for further expansion therein in the cylinder next in the series after the cylinder from which the steam was exhausted, the last mentioned means including means driven by said turbine for compressing the steam withdrawn from the engine and superheating it me degree providing a substantial degree of superheat at the pressure to which the steam is compressed.

9. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein, a turbine for expandingsteam finally exhausted from the engine to a pressure below that to which it can be expanded in the engine, and means for withdrawing substantially all of the steam exhausted from the high pressure cylinder and returning it to the engine for further expansion therein in the cylinder next in the series after the high pressure cylinder, the last mentioned means including 1 means driven by said turbine for compressing the steam withdrawn from the engine and super heating it to a degree providing a substantial degree of superheat at the pressure to which the steam is compressed.

10. In a steam power plant, a reciprocating steam engine having a firstcylinder and a second cylinder, receiver space connecting the outlet of the first cylinder with the inlet of the second cylinder, a steam turbine, a conduit for conducting steam finally exhausted from the engine to the turbine, a condenser, a conduit for conducting the exhaust from the turbine to the condenser, compressor means driven by said turbine, a conduit for conducting substantially all of the steam exhausted from said first cylinder to said compressor means, a conduit for conducting said steam from said compressor means to the inlet of said second cylinder, said compressor means being constructed to increase the pressure of the steam as returned to the engine and to impart thereto a substantial degree of superheat at its compressed pressure, and means in said receiver space for preventing flow to said first cylinder of the compressed steam returned to the engine.

11. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a. condenser, an exhaust steam turbine for expanding steam to a lower pressure than that to which it can be expanded in the low pressure cylinder of the engine, said turbine receiving steam exhausted from the low pressure cylinder of the engine and exhausting to said condenser, a compressor driven-by said turbine, means for conducting at least the major portion of the steam exhausted from one of said cylinders at intermediate pressure and for delivering it in substantially dry state to said compressor whereby to cause the heat due to compression to add superheat to the steam, and means for conducting the steam from the compressor to the means for admitting steam to the cylinder next in the series after the cylinder exhausting to the compressor.

a compressor driven by said turbine, a conduit for conducting at least a major portion of the steam exhausted at intermediate pressure from one of said cylinders to said compressor, a separator in said conduit for drying the steam supplied to the compressor, whereby to cause the heat due to compression to add superheat to the steam, and a conduit for conducting the steam from the compressor to the means for admitting steam to the cylinder next in the series after the cylinder exhausting to the compressor.

13. In a steam power plant, a reciprocating steam engine having a first cylinder and a second cylinder, a receiver space connecting the outlet of the first cylinder with the inlet of the second cylinder, a steam turbine, a conduit for conducting steam finally exhausted from the engine to the turbine, a condenser, a conduit for conducting the exhaust from the turbine to the condenser, compressor means driven by said turbine, a conduit for conducting substantially all of the steam exhausted from said first cylinder to said compressor means, a water separator in the second mentioned conduit for insuring delivery to the compressor means of substantially dry steam, a conduit for conducting steam from said compressor to the inlet of said second cylinder, said compressor means being constructed to increase the pressure of the steam as returned to the ening pressure energy in the steam gineand to impart thereto a substantial degree of superheat, and means in said receiver space for preventing flow to said first cylinder of the compressed steam returned to the engine.

14. In a steam power plant, a reciprocating panded in said engine comprising a pump device driven by said turbine, a conduit for conducting steam exhausted from one of said cylinders to the suction side of the pump device, and a conduit for conducting steam from the discharge side of the pump device to the means for admitting steam to the cylinder next in the series after the cylinder exhausting'the steam conducted to the pump device, and means providing resistance to fiow of steam pumped to the engine for convertderived from the pump device to heat energy.

15. In a steam power plant, a reciprocating steam engine having a plurality of cylin'dersfor serial expansion of the steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a receiver between two consecutive cylinders, a partition dividing said receiver into two chambers, an anterior cylinder in the series exhausting into the first of said chambers, a pump device, a conduit connecting said first chamber with the suction side of said pump device, and a second conduit connecting the pressure side of said pump device with'said second chamber which contains the means for admitting steam to the next cylinder in the series, said pump device being constructed with so low an operating efiiciency that its output is substantially transformed into heat absorbed by the steam. v a

16. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a receiver between two consecutive cylinders, a partition dividing said receiver into two chambers, an anterior cylinder in the series exhausting into the first of said chambers, a pump device, a conduit connecting said first chamber with the suction side of said pump device, a second conduit connecting the pressure side of said pump device with said second chamber which contains the means for admitting steam to the next cylinder in the series, and throttling means in said second conduit.

17. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a pump device, a conduit for leading exhaust steam from one of said cylinders to the suction side of said. pump device, a second conduit connecting the pressure side of said pump device with the means for admitting steam to the next cylinder in the series, and throttling means in said second conduit.

18. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein. means for admitting steam to and exhausting steam from each of said cylinders, a receiver between two consecutive cylinders, a partition dividing said receiver into two chambers, an anterior cylinder in the series exhausting into the first of said chambers, a steam turbine driven by steam finally exhausted from said reciprocating steam engine, a turbo-compressor driven by said steam turbine and arranged to compress the steam exhausted into said first chamber, a conduit connecting said first chamber with the suction side of said turbo-compressor, a second conduit connecting the pressure side of said turbo-compressor with said second chamber to admit therein steam at a higher pressure than the steam exhausted into said first chamber, a condenser adapted to condense the exhaust steam of said steam turbine, and a bypass pipe provided with a stop valve and connecting the exhausting means of the last cylinder in the series with said condenser.

19. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein, means for admitting steam to and exhausting steam from each of said cylinders, a receiver between two consecutive cylinders, a partition dividing said receiver into two chambers, an anterior cylinder in the series exhausting into the first of said chambers, a steam turbine driven by steam finally exhausted from said reciprocating steam engine, a valve in said partition wall adapted to automatically open in the direction of the normal steam flow between the cylinders when the steam pressure in the inlet portion of the re- .inder in the series with said condenser.

20. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein, a receiver space between two consecutive cylinders, means dividing said receiver space into a first chamber and a, second chamber, the first one of said two cylinders exhausting to the first of said chambers and the second cylinder of said two cylinders receiving steam from the second of said two chamvbers, a steam turbine driven by steam finally exhausted from said reciprocating steam engine, a compressor driven by said steam turbine, a conduit for conducting steam from said first chamber to the suction side of said compressor, and a second conduit for conducting steam from the serial expansion of the steam therein, a receiver space between two consecutive cylinders, means dividing said receiver space into a first chamber and a second chamber, the first one of said two cylinders exhausting to the first of said chambers and the second cylinder of said two cylinders receiving steam from the second of said two chambers, a steam turbine driven by steam finally exhaustedfrom said reciprocating steam engine, a compressor driven by said steam turbine, a conduit for conducting steam from said first chamber to the suction side of said compressor, and a second conduit for conducting steam from the pressure side of said compressor to said second chamber, said compressor being constructed with relatively low operating e-fliciency whereby to utilize only a portion of the energy derived from said turbine to increase the pressure of the steam and to utilize a substantialportion of the energy derived 'from said turbine to impart to the compressed steam a substantial degree of heat of superheat and to thereby provide for substantially superheated steam operation of the second of said two cylinders.

22. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for serial expansion of the steam therein, a receiver space between two consecutive cylinders, means dividing said receiver space into a first chamber and a second chamber, the first oneof said two cylinders exhausting to the first of said chambers and the second cylinder of said two cylinders receiving steam from the second of said two chambers, a steam turbine driven by steam finally exhauste'cl from said reciprocating steam engine, a compressor driven by said steam turbine, a conduit for conducting steam from said first chamber to the suction side of said compressor, and a second conduit for conducting steam from the pressure side of said compressor to said second chamber, andvalve means providing for direct fio-w of steam from said first chamber to said second chamber when the pressure in the first chamber exceeds the pressure in the second chamber.

' JOHAN ERIK JOHANSSON.