US2132212A

US2132212A - Means for utilizing exhaust steam

Info

Publication number: US2132212A
Application number: US698512A
Authority: US
Inventors: Johansson Johan Erik
Original assignee: Goetaverken AB
Current assignee: Goetaverken AB
Priority date: 1928-06-05
Filing date: 1933-11-17
Publication date: 1938-10-04
Anticipated expiration: 1955-10-04

Description

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@eto 4l, H9 J. E. JoHANssoN MEANS FOR UTILIZING EXHAUST STEAM Filed NOV. 17, 1953 5 Sheets-Sheet l f Vgn @5am/@MM a ATTORNEY @QL 4, 1938., L E, JOHANSSON ZSZHZ MEANS FOR UTILIZING EXHAUST STEAM Filed NOV. 17, 1935 5 Sheets-Shes?I 2 Whig 7 65 6g @ffmwi A TORNEY @ct- 49 @3%. J. E. JoHANssoN MEANS FOR'UTILIZING EXHAUST STEAM Filed Nov. 17, 1935 3 Sheets-Sheet 5 2 IVENTOR i ATToRN d Patented Cet. 4, 1938 PATENTv OFFICE 2,132,212 MEANS FOR UTLLIZING EXHAUST STEAM Johan Erik Johansson, Goteborg, Sweden, as-

signorv to Aktiebolaget Gtaverken, Goteborg, Sweden, a corporation of `Sweden Application November 17, 1933, Serial No. 698,512 In Sweden June 5, 1928 4 Claims.

This application is a continuation in part replacing my copending application lSerial No. 383,132, filed August 2, 1929.

The present invention relates to means for utilizing exhaust steam of reciprocating steam` engines and has for its general object the provision .of means for transforming the available heat content of the exhaust steam into energy absorbed by the steam during expansion in the rem cipro'cating steam engine. More particularly, the

invention relates to steam power plants comprising a reciprocating steam engine, the exhaust steam of which is utilized in a steam turbine driving one or more pump devices in. order to compress steam expanded in the reciprocating steam engine to a higher pressure, thus transforming the outputof the exhaust steam turbine into heat energy absorbed by the steam in the reciprocating engine.

Still more particularly, the invention aims to provide combinations and arrangements of parts in such a manner that all of the cylinders of the reciprocating steam engine can be driven by superheated or at least drier steam than hitherto has been the case.

Another object of this invention is to provide means for increasing the smallest 'quantity of steam conveyed by the pump device per unit of time in order to obviate a steamflow through the pump device in a direction opposite to the intended one.

A further object of the invention consists in the provision `of a pump device for the purposes set forth above, which under the greatly varying operation conditions can be driven with the highest possible efficiency. g

A still further object of the invention is to provide means for bleeding steam from the reciprocating engine for heat exchanging purposes, said means being arranged so as to conduct, as far as possible, vall moisture from the engine to the heat exchanging apparatus.

For a better understanding of the nature of the invention and the manner in which it is carried into eiect, reference may be had to the accompanying drawings forming a part of this specication and the following description thereof.

In the drawings:

Fig, l is a plan view, partly in section, showing an embodiment of the invention;

Fig. 1a is a section taken on the line Ia--Ia of Fig. 1.

Fig, 2 shows an indicator diagram;

Fig. 3 shows a modification of a detail of Fig. 1 in section.

Figs. 4 and 5 are diagrams illustrating the mode of operation of the turbo compressors used in the steam power plant according to the invention;

Fig. 6 is a modification of the steam power plant illustrated in Fig. 1; ,.5 Fig. 'l is a sectional view in an enlarged scale taken on the line VII--VIIof Fig. 6; and

Figs. 8 and 9 are details of Fig. '7.

Referring now to Fig. 1, reference numeral I indicates a reciprocating steam engine arranged for triple expansion of steam in the cylinders 2, 3 and 4 thereof, high pressure steam being supplied from the steam generator 5 through the conduit 9 to the main stop valve 'I and, therefrom, to the piston valve 8. After expansion in the high pressure cylinder 2 the steam passes through the pipe 9, which serves as a receiver, into the distributing valve chest II) and to the piston valve II and, therefrom, into the intermediate pressure cylinder 3. After having expanded therein, the steam is exhausted into the receiver I2 and then enters, by means of the slide valve I3, the low pressure cylinder 4 which exhausts the steam expanded therein into the exhaust steam pipe I4 connected with the condenser I5. The pipe I4 is further connected by means of a pipe I6 with an exhaust steam turbine Il driven by steam nally expanded in the reciprocating engine I. After having expanded in the exhaust turbine I'I, the steam flows through a conduit I8 into the condenser I5.

The steam turbine II drives by means of a shaft 92, a low pressure turbo compressor vI9 rotating at the same speed as the turbine. A gearing 2U connected with the turbine drives, by 3 means of a shaft 93 partly lying below the shaft 92, a reciprocating high pressure compressor 2l. The exhaust steam pipe I4 is also connected with a pipe 22 conducting steam to the suction side of the compressor I9.

Stop valves

23, 24, and 25 are arranged in the pipes I4,l I6, and 22, respectively. A container 26 located in the pipe 2.2 serves to equalize the diierence between the quantity of steam flowing into the pipe 22 and the quantity of steam sucked in by the compressor I9 per unitof time.' The pressure side of the compressor I9 is connected, by means of a pipe 2l, with the receiver I2 at a point .adjacent the slide valve I3. A pipe 28 connects the receiver I2 with the suction side of the compressor ZI. The pressure pipe 29 of this compressor is connected with a superheater 39 arranged in the flue passage 3I of the boiler 5 and, by means of pipe 32, with the receiver pipe 9 at a point adjacent the piston valve I I. A by-pass pipe 44 havingv a 55 throttle valve 45 connects the pressure side of the turbocompressor with its suction side.

During normal operation, the stop valve 23 is in closed position whereas the

valves

24 and 25 are opened so as to allow flow of steam from the exhaust pipe I4 to the steam turbine I"I and to the compressor I9. The steam sucked in by the compressor I9 is compressed to a pressure which is substantially equal to the pressure prevailing in the receiver I2, whereupon this steam, which has been superheated or at least dried by compression, is conducted through the pipe 21 to the said receiver for further expansion in the low pressure cylinder 4. It is obvious that the mixture of steam entering the low pressure cylinder will have a higher temperature or be drier than the steam exhausting from the intermediate pressure cylinder. low pressure cylinder will be increased materially and the low pressure cylinder will be fed with superheated or dry steam. In this manner, a portion of the output of the exhaust steam is rendered serviceable for the low pressure cylinder in the form or" an increased quantity of steam of a higher temperature or at least having less moisture and a pressure suitable for utilization in this cylinder. The receivers 9 and I2 communicate in a similar manner with the high pressure compressor 2l by means of the

conduits

28, 29, and 32. The steam taken out from the receiver I2 is compressed by the reciprocating compressor 2| to a pressure which is substantially equal to the pressure Vprevailing in the receiver 9. 'Ihe compressed steam which has been superheated by compression is still more superheated in the superheater 3B.

As will be seen from the drawings, the steam which has been compressed by the high pressure compressor is conducted back to the reciprocating engine at a point situated behind the high pressure cylinder, since the compression of steam up to the pressure prevailing in the live steam pipe would cause considerable diiculties. Therefore, I prefer to compress the steam to a pressure not higher than the pressure prevailing in the irst receiver.

If it is desired to disconnect the turbine and the compressors, this may be eiected by conducting the steam through the exhaust pipe I4 directly into the condenser I5. For this purpose, the valve 23 is opened and the

valves

24 and 25 are closed.

In Fig. 1, I have also shown means for bleeding steam from the reciprocating steam engine, this steam being used for preheating of feed water. For this purpose, three

feed water preheaters

33, 34, and 35 are connected to the reciprocating steam engine by means of

pipes

36, 31 and 38 respectively. 'Ihe feed Water passes from the condenser I5 through the pipe 39 and the preheaters to the pump device 40 and, therefrom, into the boiler 5. 'I'he feed Water preheater 33 is connected with the exhaust side of the valve chest of the low pressure cylinder so that a portion of the steam finally exhausted in the reciprocating engine is conducted to this preheater. The next preheater 34 is connected with the receiver I2. As the pressure side of the compressor I9 is connected with the same receiver, I have chosen such an arrangement of the

pipes

21 and 31 that steam compressed by the compressor I9 is conducted into the receiver I2 at a point adjacent the slide valve I3 whereas the steam to be tapped off from this receiver is taken out at a point adjacent the piston valve II. Because of the arrangement Thus, the output of the thus provided superheated steam delivered from the compressor will tend to flow in a relatively short and direct path to the slide valve I3, whereas the preheater 34, the inlet of which is adjacent the valve II, will tend to draw oi the relatively low quality steam discharged from the latter valve. With the arrangement illustrated, the natural path of flow of steam admitted to the receiver I2 from valve II and from the compressor discharge conduit 21 will tend to maintain a substantially higher quality of steam into the zone adjacent to the valve I3 than in the Zone adjacent the inlet to the preheater. Consequently, the high temperature steam delivered from the compressor is substantially utilized in the succeeding cylinder of the engine and preheating is accomplished by steam of relatively low quality as exhausted to the receiver.

Itis further to be noted that in view of the general flow of the steam through the receiver from the valve II toward the valve I3, the relative positions of the inlet end of conduit 28 and the outlet end of conduit 2 leads to a natural tendency for conduit 28 to withdraw steam of lower rather than of higher quality from the receiver. If this latter steam contains moisture, such moisture will, as far as possible, be drawn oi by the pipe 31. In the same manner, the steam compressed by the high pressure compressor 2l enters the receiver 9 at a point adjacent the piston valve II, Whereas the pipe 38 is connected with the receiver 9 at a point adjacent the outlet of the high pressure cylinder 2.

In order to reduce the dimensions of the compressors and the work of compression, the pressure of the steam supplied to the compressors should, if possible, be higher than the pressure prevailing in the cylinders during the exhaust period. This may be effected if the steam of a higher pressure exhausted from the cylinders during the exhaust lead period is supplied to the compressors, While the steam exhausted during the exhaust period is utilizedv for further expansion in the following cylinder or in the exhaust turbine respectively. Therefore, if accordatthe point 4I, an increased average pressure of the steam supplied to the compressor may be obtained.

Y For this purpose, the stop valve 25 inthe conduit 22 may be replaced by a non-return valve opening in the direction to the suction side of the compressor. Fig. 3 shows this modified arrangement. As the steam quantity entering the pipe I4 during the exhaust lead period of the loW pressure cylinder is materially greater than the steam quantityentering simultaneously the steam turbine I1, the pressure in the conduit I4 will increase. The non-return valve 42 then opens and the greatest portion of the steam exhausted during the exhaust lead period flows into the container 26. As during the exhaust period the pressure decreases in the conduit I4, the non-return valve closes and prevents the steam of higher pressure from ilowing back to the conduit I4. The steam exhausted during the exhaust period will then flow to the steam turbine I1.

On account of the great variations of the oW of steam through the cylinders of the reciprocating steam engine and the great changes in the steam quantities conveyed to the compressors,

til() pr-.essor per unit of time.

the compressors will Work A.under peculiar operating-conditions. I vhave found that, if the turbo compressor is constructed in the ordinary manner so as to normally give its maximum efliciency with the steam quantity conveyed per unit 4of time, the efficiency obtained will actually be considerably lower. I therefore, construct the turbo compressor so that its maximum efficiency occurs with a 'quantity'of steam exceeding the average quantity conveyed per unit of time by at least 25 per cent. The operating conditions of the turbo compressor will be described more particularly in connection with Figs. 4 and 5.

f Referring to Fig. 5, V represents the volume which, zat .a certain `crank position of the reciproeating steam engine, flows through the com- The line 46 indicates the changes in volume during one crank revolution and the line 41 represents the average volume Vm conveyed during said period. In the corresponding diagram in Fig. 4, the abscissae of the coordinate system represent the volume conveyed to the compressor andthe ordinates thereof represent the efliciency of the compressor. Curve 48 indicates the changes of the pressure efficiency n with the volume V with a compressor intended to give its maximum eiliciency at the average volume Vm, While vcurve 49 indicates the changes of the efriciency of a `compressor which gives its maximum -eiiiciency at a volume of 1.5 Vm. Ina compressor loperating .with the changes of volume indicated by curve 46 and having an eiciency curve according to 48, `an average eiciency is obtained which'corresponds to the distance 5I indicated in the diag-ram, whereas the average efliciency of a compressor with an efficiency curve according to 49 reaches a considerably higher value represented by the distance 52. The upper ends of these two distances 5I and 52 are situated on a curve 5l) on which a plurality of points may be calculated for compressors with other efficiency curves. After such Va curve 5l] has been plotted it will .be possible to determine the average efliciency 11m under the conditions indicated for a compressor which is dimensioned so as to have its maximum efficiency at the volume correspond- 'ing vto the point of the curve where the average efficiency is read off.

`The curves 48 land 43,'and corresponding curves for other volumes, have ybeen obtained by tests with turbo compressors, and for the determina- .tionof curve .50 the following equation has been Iused.:

EV'v] Vmzf where t represents the time during which .the volume V iiows through the compressor. i If 2t represents the time of one revolution of the reciprocating steam engine, this expression can be replaced by 360, t being measured in degrees on the `diagram in Fig. 5. For the calculation of 11m for a compressor having an efciency curve according :to curve 48, for example, the volume V is measured for a certain small angular displacement t" v.on the diagram in Fig. 5. With .the value ofV'thus obtained the value of the corresponding n is `measured Von the curve 48. After the wholediagrarn'li has been vmeasured in this manner and multiplied by the corresponding q-values, EVqcan -be obtained and thus also EVr] Vm 36o llherehyapointshas been .deter-mined .on curve 50.

By a similar calculation for a plurality of other efciency curves the determination of curve 5D has been effected;

It will .appear from the form of this curve that it has its lowest value at small volumes, and that it reaches a'maximum value at a Volume of about 1.5 Vm, whereupon it slowly falls with greater V-values. Consequently, the compressor should .be so constructed as to have its maximum efficiency at a volume of 1.5 Vm, it being possible, however, to permit variations of this Volume between the limit values 1.25 Vm and 2.5 Vm Without :the average efficiency being materially lowered. By an overdimensioning of the compressor,

which may be effected, for instance, by increasing the width ofthe channel areas of common turbo compressors, the Iadditional advantage is obtained that the friction losses during the flow of steam through the compressor are reduced.

In Fig. 4 also a curve 53 has been shown, which indicates the pressure-increasing ability of the turbo-compressor at different values of the steam volume conveyed. It will be seenfrom the diagram that the pressures are remarkably low at small steam volumes, that is to say for the extent Ikof lthe `diagram denoted by 54-55. This circumstance is explained by the fact that av per-iodic flow of steam `takes place through the com- .pressor in a direction opposite to the intended one for said portion of the diagram. As the .energy .transferred by the compressor to the steam is lsubstantially constant, the main portion of the energy is under such circumstances transformed into an increase `in temperature of the steam. An increase in pressure as far vas possible would be, however, more `desi=rablesince this latter form .of energy is easier to transform, by means of the reciprocating steam engine, into mechanical work. To ensure -such an increase of the pressure, the

.turbo compressor t9 is by-passed Lby pipe -44 in which is inserted a throttle valve 45. By means of pipe 44 a portion of steam .which has already :been compressed is returned to the suction side of vthe compressor, in order thus to prevent the entrance :of too .small -steam Volumes conveyed by the compressor per unit of time. In Fig. 5, the vdiagram 'designated `by 46 shows the variations of the Ivolume Aconveyed by the compressor per vunit of time if :there is no return of steam from the pressure side to the `suction side thereof, and the combination with curve 53 on Fig. 4 makes it iclear that the pressures corresponding .to the smallest volumes will fall on the portion of the pressure curve 53 extending between the points 54and :55.

In consequence of the steam quantity which vreturns through the `by-pass pipe 44 to the suction side of the compressor, :a steam quantity corresponding to curve 56 indicated -in Fig. 5 Aby chaindotted lines will then flow through the compressor, so that all volumes ycorresponding to the portion 54-55 willfbe avoided. With the arrangement .-set forth, the compression in the comvpressor'may thus 'be caused to develop exclusively according 4to the portionon the right of point 55 of the pressure curve .53 shown in Fig. 4, the best economical result being thus obtained, in that the `energy supplied by the compressor is transformed as far as possible into an increase of the pressure of the steam. l

In the modification shown in Figs. `6 to -9, the live Asteam enters `the distributing valve chest 51 zand, .after .having 'expanded in the high pressure cylinder 2, enters the vreceiver :58. The steam .then `ovvs through the intermediate and .low

pressure cylinders 3 and 4, respectively, into the exhaust steam pipe I4, as described in connection with Fig. 1. The piston valve II of the intermediate pressure cylinder and the slide valve I3 of the low pressure cylinder are connected by means of a pipe 59 which serves as a part of the low pressure receiver I2. The exhaust steam turbine I1 drives two turbo compressors I9 and 60, respectively. 'I'he suction side of the low pressure compressor is connected to pipe 22 and its pressure side is connected, by means of pipe 21, with the low pressure receiver 59, I2. By means ol the pipe 28, the high pressure cornpressor 50 sucks in steam from the receiver 59, and the co-mpressed steam is conducted through pipe 29, superheater 30, and pipe 32 into the receiver 58 at a point adjacent the piston valve II of the intermediate pressure cylinder 3. The pipe 31 for bleeding steam from the low pressure receiver is connected to pipe 59 at a point adjacent the steam outlet chamber 6I of the intermediate pressure cylinder, while the pipe 38 through which steam of higher pressure is bled, is connected with the outlet chamber 62 of the high pressure cylinder. Y

Allof the parts indicated in Figs. 6 and '7 by the same reference numerals as in Figs. 1 and 3 serve the same purpose and operate in the same manner as the corresponding parts of Figs. 1 and 3.

While the low pressure compressor I9 is bypassed by a pipe 44 with a throttle valve 45 in the same manner and for the same purpose as in Fig. l the high pressure compressor 69 is bypassed by a pipe 63 connecting the receiver 58 with the receiver 59. The connecting pipe 63 is provided with a stop valve 64 and with a controlling device 65 which is shown on a larger scale in Fig. 9. The controlling device 65 comprises a cylinder 66 and a double piston 61 rigidly connected with the piston valve I I. The upper part of piston 61 and the cylinder 66 are provided with

apertures

68 and 69, respectively, these apertures controlling the ilow of steam from the receiver 58 through the pipe- 63 to the receiver 59, depending on the position of the double piston 61 during each revolution of the reciprocating engine; The two parts of the double piston and the apertures are situated relatively to each other in such a manner that a flow of steam through pipe 63 is possible only during those periods in the engine cycle when the steam quantity conveyed by the turbo compressor 60 tends to fall below the value indicated by the point 55 in the diagram of Fig. 4. During such periods the controlling device 65 is opened by movement of the piston valve I I so that, during these periods, a steam quantity according to the curves 10 in Fig. 5 will flow through the compressor 60 in order to prevent the entrance of too small volumes conveyed by the compressor per unit of time. The arrangement of the controlling device is somewhat more complicated than the single throttling valve 45, but offers, on the other hand, the advantage that an increase of the steam volume conveyed by the compressor takes place only during two short periods of each revolution of the reciprocating steam engine, thus decreasing the necessary amount of work required by the compressor.

In the modification according to Figs. 6 to 8, I have also shown an arrangement adapted to draw off steam from the low pressure cylinder 4 to the low pressure compressor I9 during the expansion in the cylinder, an exhausting means being controlled so as to open at a point 43 (Fig.

2) before the beginning of the exhaust lead period representedat 4|, whereby steam of a higher pressure is supplied to the suction conduit of the compressor. In this case, the pressure curve will sink somewhat as indicated in Fig. 2 f

by dash lines.

To effect this mode of operation, the cylinder covers 1I and 12 of the low pressure cylinder are provided with valves 13 and 14, respectively, connected with

pipes

15 and 16, respectively, which supply the steam drawn off from the cylinder to the container 26 and the compressor I9. The

pipes

15 and 16 may be connected by a pipe 94. Under the influence of springs 11 and 18, the valves 13 and 14 are normally kept in closed position. .The valve 13 is actuated by means of a lever 19 which is connected with a rod 80 guided by a bracket BI. The lower end of the rod 88 is provided with a roll 82 cooperating with a cam wheel 88. A spring 84 prevents disengagement of the roll 82 and the cam wheel 83. The cam wheel is keyed on the crank shaft 85 and has an outwardly projecting cam 86 and, o-n the opposite side, a recess 81.

When the cam wheel is turned from the position shown in Fig. 8 in a counter-clockwise direction, the cam 86 will cause an upward movement of the rod 80 and a movement of the lever 19 about its iulcrum 88 in a clockwise direction, whereby the valve 13 is opened against the resistance of the spring 11. The cam 86 has such a position relatively to the crank 89 of the low pressure cylinder that the valve 13 begins to open at a point of the steam process corresponding to the point 43 in Fig. 2. The valve 14 on the other cylinder cover is actuated in a similar manner by means of the lever 90 likewise connected with the rod 88. When the recess 81 of the cam wheel is in a position below the roll 82, the rod 80 will be moved downwardly and the lever 90 turned in a counter-clockwise direction, thus opening the valve 15 against the resistance of the spring 18. By means of a hand lever 9|, the cam wheel 83 is movable to a position indicated by 92, the valves 13 and 14 then being out of operation.

While in the foregoing description I have confined my consideration to a. steam power plant comprising a triple expansion steam engine and two compressors, it will be understood that the invention is not confined tof this specific arrangement but may equally well be embodied in steam power plants in which two or more cylinders are employed for expanding the steam down Afrom boiler pressure to exhaust pressure and only one compressor is provided for the compression of steam. f

what 1 Claim iszl. In a steam power plant, a reciprocating steam engine having a plurality of cylinders for multiple stage expansion of steam in the engine, said cylinders being double acting and the opposed ends of the same cylinder operating to expand steam through the same pressure range, means for admitting steam to and exhausting steam from each of said cylinders, a compressor, a turbine for driving said compressor, a conduit for conducting steam exhausted from one of said cylinders to the suction side of said compressor and a second conduit for conducting compressed steam from said compressor back to said engine for reexpansion therein, said compressor being constructed to operate with maximum efliciency when steam is supplied thereto at a rate equal to at least one and one-quarter times but not exceeding two and one-half times the average rate at which steam is delivered by the engine.

2. In a steam power plant, a reciprocating engine having a plurality of cylinders for multiple stage expansion of steam in the engine, said cylinders being double acting and the opposed ends of the same cylinder operating to expand steam through the same pressure range, means for admitting steam to and exhausting steam from each of said cylinders, an exhaust steam turbine for expanding exhaust steam from said engine to a pressure lower than that to Which the steam canl be expanded in the engine, a compressor driven by said turbine, a conduit for conducting steam exhausted from one of said cylinders to the suction -side of said compressor and a second conduit for conducting compressed steam from said compressor back to said engine for reexpansion therein, said compressor being constructed to operate with maximum eiciency when ste-am is supplied thereto at a rate equal to at least one and one-quarter times but not exceeding two and one-half times the average rate at Which steam is delivered by the engine.

3. In a steam power plant, a reciprocating engine having a plurality of cylinders for serial second conduit connecting said one of said cylinders with the suction side of said pumping means, valve means for controlling iiow of steam through said second'conduit, said valve means being opened and closed in accordance with the position of the crank shaft of said engine to permit steam to flow through said second conduit during a predetermined period of the engine cycle, and a third conduit for returning the steam delivered from said pumping means to said engine .for further expansion therein.

4. In a steam power plant, a reciprocating 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 steam turbine, a conduit for conducting exhaust steam from said engine to said turbine, pumping means driven by said turbine, a second conduit for' conducting exhaust steam from said engine to the suction side of said pumping means, a third conduit connecting the low pressure cylinder of said engine with the suction side of said pumping means, valve means for controlling flow of steam through said third conduit, said valve means being opened and closed in accordance with the position of the crank shaft of said engine to permit steam to fioW through said third conduit during a predetermined period of the engine cycle, and a fourth conduit for returning steam delivered by said pumping means tosaid engine for further expansion therein.

JOHAN ERIK JOI-IANSSON.