US1494354A - Steam turbine - Google Patents

Description

H. L.. GUY

STEAM TURBIN'E May 2U, 1924.

Filed Ju'ly 15 1919 6 Shees-Sheet 2 WTNESSESZ mi? ATTORNEY H. L. GUY

STEAM TURBINE May 2o. 19241i v v 1,494,354

Filed July 1'5 1919 6 Sheets-Sheet 5 WITNESSES' ATTORNEY H. L.. GUY

STEAM TURB-INE May 20 192%.,

1919 6 Shees-Sheet 4 Filed July l5 EEG @"W LNVENTOR ATTORN EY STEAM"TURB1NE 6 Sheets-Sheet 5 Filed July 15 1919 TTGRNEY 6 Sheets-Sheet 6 H. L.. GUY

STEAM TURBINE Filed July 15 1919 INJENTOR W' ATTORNEY Way 2@ g i924.

Patented May 20, 1924.

'I' ST TES HENRY LEVJIS GUY, OF MANCHESTER, ENGLAND, ASSIGNOR, BY

htdaa PATENT FEEQE..

MESNE ASSIGN- PoanrroN or PENNSYLVANIA.

STEAM TURBINE.

Application filed ,Tu1y 15, 1919.

To all whom t may concer/a:

Be it known that I, HENRY Lnwrs GUY,

a subject of the King of Great Britain, and

a resident of Victoria Park, Manchester, in the county of Lancaster, England, have invented a new and useful Improvement in or Relating to Steam Turbines, of which the following is a specification.

This invention relates `to steam turbines having two or more separate elements or sections and in which, owing to the various elements or sections being mounted on the same shaft or 'otherwise coupled or geared together, one or more of said elements or i5 sections at times rotate idly while the other section or sections are in operation. An example of a turbine of this kind is a turbine used for marine propulsion provided with both ahead and reverse sections or cruising and full power sections mounted on the same shaft. Another example is a back pressure turbine combined with a high pressure turbine the two turbines being directly coupled together.

In such turbines when one or more of the elements or sections is operative and the other section or sections is running idly the latter will be rotating in a comparatively stagnant atmosphere. A considerable amount of work is required to rotate the idle wheels of the turbine in this atmosphere, and as there is no appreciable How of steam in the idle section of the turbine the work absorbed in disc friction and windage raises the temperature of the surrounding atmosphere.

Asvthe amount of work done in disc friction and windage is considerable the atmosphere in which the idle section rotates may be raised to a temperature so high as to endanger the turbine either by causing severe stresses through differential expansion of the diaphragm and casing or by raising portions of the turbine made of cast ironto a temperature at which it grows and permanent deformation takes place from this cause.

The present invention has for its object to provide improved means for efficiently preventing the temperature of any section of the turbine or portion thereof which is being rotated idly from being raised to such a degree as might endanger the turbine and Serial No. 310,975.

according thereto an idly rotating section of theturbine is supplied for this purpose with comparatively cool steam through a pipe, passage or the like, which is distinct from any packing gland which may form a channel through which steam can leak from one section of the turbine to another. Such pipe or passage will usually be external to the turbine cylinder but may be contrived in the cylinder itself or in a diaphragm separating two sections of the turbine. f Usually the steam for cooling an idly rotating section would be supplied from an operative section of the same turbine in which it has been cooled as a result of doing work. In some cases, however, the steam for cooling purposes may be supplied from an auxiliary engine, 'a low pressure steam main or other. available source of steam at a suitable temperature.

Where the steam for cooling an idle section is supplied from an operative section of the turbine various arrangements in accordance with the invention may be adopted, the most suitable arrangement depending,1 amongst other things, upon the construction of the turbine unit itself. For example, a pipe or passage may be provided interconnecting two sections of the turbine for the purpose of passing steam from vwhichever section of the turbine may be in operation to the section which is running idly. Alternatively a pipe or passage may be provided with a non-return valve so that the steam will flow through it in one direction only. Such'an arrangement will supply steam for cooling one section of the turbine only and if the other section or sections are also to be cooled and leakage steam is not available or sulicient for this purpose an additional pipe or pipes with non-return valves therein must be provided for supplying steam to such other section or sections.

In many eases the amount of heat generated by disc friction and windage when one section runs idly is much greater than when the 'other section of the turbine is rotating idly. For example, this is generally the case with turbines used for marine propulsion having ahead and reverse sec tions the disc friction and windage of the ahead section when rotating idly being much greater than that of the reverse section under similar conditions. lt is consequently necessary rto supply a much larger quantity of' steam to cool the ahead section than is needed to cool the reverse section under idle running conditions. In some instances the separate sections although mounted on the same shaft are contained in separate cylinders. There the separate sect-ions of the turbine are contained Within a single cylinder or casing and are separated from each other by a diaphragm provided With a packing gland at the point Where the shaft passes through the diaphragm there will always be a certain amount of leakage steam flowing through this gland from one section of the turbine to the other which Will act in keeping the idle section cool. It the gland is so arranged that the steam leaking through it is suiiicient 'to cool the ahead section when the reverse section is in operation the amount of steam leaking through the gland When the ahead section is operative will be much greater and far more than is necessary to cool theidly rotating reverse section and Will represent a loss which will considerably reduce the etliciency of the turbine when the latter is propelling the vessel ahead, which is the normal condition of operation. In cases ot this kind sutcient steam for cooling the section having the lesser disc friction and Windage may be supplied by leakage through the gland, a pipe or passage being provided arranged f to convey additional steam in the contrary direction to the section havingr the greater disc friction and Windage when the latter is running idle.

The quantity o't steam necessary to cool a section of the turbine which is .running idly may yhe controlled by suitably proportioning the size of the pipe er passage for supplying the steam for this purpose, or by means of a valve operated either manually or automatically, or alternatively the pipe or passage may be provided with a nonreturn valve arranged to open automatically When a greater pressure exists on that side ot the valve from which the steam is to be drawn.

Where a pipe or passage is provided Without a controlling valve the points in the sections of the turbine to which the pipe or passage is connected should be so chosenA that the pressure of the steam existing at suoli points will cause ai greater quantity of steam to be passed through said pipe or passage When the section of the turbine having the lesser disc friction and ivindage is operating than when the section havingthe greater ydisc friction and vvindage is opera.- tive.

In order that the invention may be more clearly understood, several Waysy in which it may be carried into effect Will non' be more particularly clesrribed with reference to the accompanying drawings, in which, Figs. 1 to 6, inclusive, are sectional and diagrammatic views showing the application of my invention to turbines of the reversing tyoe; Fig. 7 is a diagrammatic view showing tie invention applied to a marine turbine having main and cruising section; and Fig. 8 is a diagrammatic vieiv of a back-pressure turbine to which my invention is applied.

Referring first to Figures l to 6, inclusive, the turbine here illustrated comprises a high pressure ahead section 4c and a high pressure reverse section 5, a loiv pressure ahead section 6 and a low pressure reverse section 7, the ahead and reverse sections of the high and loiv pressure portions ot the turbine being respectively located in separate cylinders as shown. The exhaust of the high pressure ahead section l is connected by a pipe 8 to the inlet of; the low pressure ahead section 6, and similarly the exhaust ot the high pressure reverse Section 5 is connected by a pipe 9 to the inlet ot theloiv pressure reverse section 7.

Connecting the high pressure ahead section l- With the high pressure reverse section 5 a pipe, indicated at 10, with a. valve 1i located therein, through which when the turbine is ruiming ahead and the reverse sections 5 and 7 are rotating idly steam will be passed from the ahead section ll into the high pressure reverse section 5, thence through the connecting pipe 9 and the loiv pressure reverse section 7 to the condenser inlet 12. The valve 11 in the pipe 10 may be either a manually controlled valve, as indicated in Fig. 1, which is opened when the ahead sections of the turbine are in operation or a non-return valve, as indicated in 2. arranged to permit steam to pass trom the ahead section il; to the reverse section 5 but not in the contrary direction. lu order that the ahead section ot the turbine may be cooled when the reverse section 5 is operative and the vessel is going astern, a pipe 13 is provided connecting the high pressurereverse section 5 With an intermediate stage oi' the high pressure aheadsection 4. Another pipe 14- connects the exhaust from the high pressure reverse section. 5 With the pipe 8 leading to the inlet of the ahead section 6 o't the low pressure turbine. The pipes 13 and 1e are respectively provided with valves 15 and 1G Which may be either manually controlledv` as in Fig. 1, in 'which case they must `he opened when the reverse sections ot the turbine are in operation or of the non-return type, as in Fig. 2, permitting steam to pass from the reverse section 5 to the ahead sections Li and "o, but not in the contrary direction. With this arrangement, when the reverse sections of the turbine are being operated and it is desired lllO to cool the idly rotating sections 4 and 6 of the ahead turbine, steam will be passed through the pipes 13 and 14 respectively into and will flow through the high pressure and vlow pressure ahead sections of the turbine and eli'ectively prevent the `temperature of these sections being raised to an undesirable degree. In place of the two pipes 13 and 14 a single pipe, as shown in Fig. 3, interconnecting the reverse and ahead sections may in some cases be sufficient for supplying all the steam necessary Jfor cooling the ahead sections 4 and 6. A

In some cases the supply of steam for cooling certain sections of the turbine may be furnished from the ahead to the reverse sections or vice versa, depending upon which sections are operative, through a pipe or passage unprovided with valves such, for instance, as that indicated at 17 in Fig. 4. Where a connection of this kind is employed the points 18, 19 with which Athe ends of the pipe 17 are respectively connected with the reverse and ahead sections of the turbine are so selectedl that normally the pressure of steam existing at these points will be such that a greater quantity of steam will be passed from the reverse section to the ahead section when the turbine is going astern and the ahead section is rotating idly than when the opposite conditionsprevail, assuming as is generally the casethat the disc friction and windage'of the ahead section is greater aha-n that ot the reverse section of the turine.

It willbe observed that in Figure the high pressure ahead section 4 is separated from the high pressure reverse section 5 by a diaphragm, as indicated at 20, with a gland 21 surrounding the turbine shaft 22. The pipe or passage for supplying steam from the ahead section 4 for cooling the reverse sections 5 and 7 when the latter are rotating idly may be dispensed with by arranging that the leakage steam passing through the gland 21 from thc high pressure section 4 shall besutficient to cool the idly rotating reverse sections of the turbine. 1With this'arrangement the leakage steam liowing through the gland 21 when the reverso section 5 is operating may in some cases be sufficient to cool the ahead section 4 of the high pressure turbine, in which cases the pipe or passage 13 may be omitted; Unless, however, the leakage through the gland 21 in this direction is excessive and such as seriously to impair the efficiency of the operation of the turbine it will be necessary to provide a pipe or passage such as the pipe 14 or the pipe 17 for supplying steam for cooling the ahead section 6 of the low pressure turbine when the latter is rotating idly owing to the vessel being driven istern. Usually, however, where leakage hrough the gland is used for cooling purposes it will be found desirable to design the gland 21 so that the leakage of steam therethrough will be sul'licient only to cool the smaller reverse sections of the turbine when running idle and not the larger ahead high pressure section, the additional steaml tor cooling the latter when running idle being supplied by a pipe or passage such as the pipe 13, as shown in Fig. 6.

The turbine indicated diagrammatically in Figure 7 comprises a main or full speed section 23 and a. cruising section 24, the rotors of both sections being mounted on the same shaft and contained either in separate cylinders, as indicated, or in a single cylinder separated by a diaphragm, asrepresented in the upper portion of Figure 1. In running at full speed and power the main section 23 only will be in operation but when running at cruising or lower speed and power both sections 23 and 24 will be active, the steam under such conditions first entering the cruising section 24 and thereafter passing through the main section 23 to the exhaust 25 by way of the valved pipe connection 26 leading from the exhaust of the cruising section 24 to the inlet ot the main section 23. The exhaust of the cruising section 24 may also be connected with the condenser through a valved pipe or passage 27, the valve in which would of course only be opened when the cruising turbine is ruiming idle. A pipe or passage 28 connects a suitable stage in the main turbine 23 with the inlet to the cruising section 24 and in this pipe is located a non-return valve 29 arranged to kpermit steam to pass through the pipe 28 only when the pressure at the inlet of the cruising section 24 is less than that in the main turbine at the point at which the pipe 28 is connected therewith.

When the turbine is developing full speed and the cruising section 24 is running idle, the latter will be connected to the condenser by opening the valve 27 and will be disconnected from the inlet to the main turbine 23 by closing the valve in the pipe 26, so that steam will then pass from the main turbine 23 through the pipe 28 to the cruising section 24 for the purpose of cooling the same and thence to the condenser. IVhen` however, the cruising section 24 is in operation the connection between the latter and the condenser will be sluit oit by closing the `valve 27 and the connection to the inlet of the main section through the pipe 26 opened. In these conditions both sect-ions of the turbine will be operative.v the steam being ad-r arrangement of a high pressure turbine 30 directly connected to a back pressure turbine 3l. From a back pressure turbine, as commonly used, the steam flows into a main and is used for heating or other manufacturing purposes and circumstances may arise in which the back pressure turbine 3l may be supplying no steam to the heater main, the high pressure turbine taking the whole of the load. In such circumstances the moving blades oi the back pressure turbine will rotate in a stagnant atmosphere and the temperature of the turbine might thereby be raised to an undesirably high degree. In order to prevent such an occurrence steam is supplied .from a suitable intermediate stage of the high pressure turbine 30 through a pipe 32 in which is a non-return valve 33 to the back pressure turbine 31. YVhere the back pressure turbine is idle and steam for cooling purposes is supp-lied in this way the connection betweenthe exhaust ot the back pressure turbine 31 and the heater main 34 will be closed by mea-ns of the usual nonreturn valve indicated at 35 andthe exhaust from the back pressure turbine 3l connected either to atmosphere or preferably a condenser, which will usually be the condenser for the high pressure turbine 30. The connection between the exhaust ot the back pressure turbine 31 and the condenser is controlled by a valve 36 which may be operated by hand or preferably automatically. `Automatic operation of the valve 36 may be secuied in a variety of ways.'

According to one Way, the valve 36 is actuated by a. power piston S7, arranged within a cylinder 40, the upper end ot the cylinder being connect-ed, vby a conduit 41, to the lower end of the operating cylinder 42 and beneath the operating piston 43 of the governor-controlled relay, at 44. The movement of the piston 37 is controlled in the contrary direction by a spring 3S. Tith such an arrangement, when the back pressure turbine 3l is not supplying any steam, or only a very small quantity, to the heater main 34 its governor valves will be closed and consequently the pressure existing belowT the power piston controlling its governor gear will be zero. The spring 38 will, under these conditions, raise the piston 37, thereby opening the valve 36 and connecting the exhaust o the back pressure turbine 31 to the condenser by way of the pipe 39.

Although more particularly described herein as applied to turbines of the disc type it is to be understood that the invention may in some cases be used with advantage in connection with turbines of the drum type. The invention is not limited to any specific arrangements for carrying the same into eiect, those hereinbefore described having been given by way of example only, and it is to be understood that the invention is to be circuinscribed only by such limitations as are imposed by the appended claims.

I claim as my invention:

l. In an elastic fluid turbine, an ahead section, a reversing section, and conduit means for conveying elastic fluid discharged from the ahead section to the reversing section to cool the latter when it is running idle.

2. In a marine turbine installation, the combination of a multiple-expansion ahead system, a multiple-expansion astern system, and means between the systems for supplying steam from an operative system to an idly-running system.

3. In a steam turbine apparatus, the combination of a plurality of alternatively operative turbine sections and means for connecting one section to the other section sov that steam from an operative section may be utilized for cooling an idly-running section.

4. In a compound turbine installation,the combination of a first turbine having a plurality of sections, a second turbine having a plurality of sections, means for conducting steam 'from an operative section of the iirst turbine to an idle section thereof, and means for conducting steam from the latter section to an idle section of the second turbine.

5. In a marine turbine installation, the combination of an ahead section having a plurality of pressure. stages, a reversing section, a conduit between the reversing section and a point in the ahead section beyond the high-pressure end thereof, and a valve in the conduit.

6. In a marine turbine, the combination of an ahead system including a plurality of pressure stages, a reversing system including a plurality of pressure stages, and means eifective, when the ahead system is in operation and the reversing system is running idly, to conduct steam from a point intermediate of said pressure stages of the ahead system to the reversing system for cooling the latter. n

7. In a turbine, 4the combination of an ahead section, a reversing section, the ahead and reversing sections being arranged to expand steam outwardly and in opposite directions.y and means for cfmducting steam from a point adjacent to the discharge end of the ahead section to the reversing section for cooling the latter when running idly.

8. In a turbine, the combination of an ahead section, a reversing section, an exhaust conduit for the reversing section, and means for connecting the latter conduit to the highpressure end of the ahead section for supplying steam to the latter for cooling purposes when running idly.

9. In a marine turbine installation, the combination of a first turbine having ahead and reversing sections, a second turbine having ahead and reversing sections, means for connecting the exhaust end of the ahead section i' the first turbine to the inlet end of the ahead section of the second turbine, means for connecting the exhaust end of the reversing section oi' the first turbine to the inlet end of the reversing section of the second turbine, and means for conducting steam from the second means to the first means when theJ reversing sections are in operation in order to supply steam to the ahead section of the second turbine for cooling the latter when operating idly.

10. In a marine turbine installation, the combination of a high-pressure turbine having ahead and reversing sections, a lowpressure turbine having ahead and reversing sections, a receiver passage between the ahead sections, a receiver passage between the reversing sections, a conduit between the receiver passages, and avalve in the con-` duit.

11. In a marine turbine installation, r"the combination of a high-pressure turbine having ahead and reversing sections, a lowpressure turbine having ahead and reversing sections, a receiver passage or connecting the ahead sections, a receiver passage for connecting the reversing sections, a conduit for conducting steaml from the high-pressure ahead section to the high-pressure reversing section for cooling the latter and for cooling the low-pressure reversing section when the ahead sections are operative and the reversing sections are running idly, and a connection between the receiver passage of the reversing sections and the inlet end of the high-pressure ahead section for supplying steam to the ahead sections for cooling the latter when running idly and when the reversing sections are in operation.

In testimony whereof I have hereunto subscribed my name this seventeenth day of J une 1919.

HENRY LEWIS GUY.

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