US892818A - Steam-turbine. - Google Patents

Description

No. 892,818. PATENTED JULY '7, 1908. S. Z. DE FERRANTI.

STEAM TURBINE.

APPLICATION IILED 00T.3l,1903.

5 SHEETS-SHEET l.

Y/ ,www1 my# y nza/e effmzz No. 892,818. A PATENTED JULY '7, 1908.

S. Z. DE FERRANTI. l

STEAM TURBINE.

APPLICATION FILED 00T.31.19os.

5 SHEETS-SHEET 2.

PATENTED JULY '7, 1908.

S. Z. DE PBRRANTI. STEAM TURBINE. `APPLIHTION* FILED 0011.31, 1903.

5 SHEETS-SHEET 3.

J5@ JM' PATENTED JULY '7, 1908.

S. Z. DE FERRANTI. STEAM TURBINE. APPLICATION FILED 00131, 190s.

5 SHEETS-SHEET 4.

MUZ/Lm No. 892,818. PATENTED JULY 7, 1908. S. Z. DE PERRANTI.

STEAM TURBINE.

APPLICATION FILED 00131, 1903.

5 SHEETS-SHEET 5.

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SEBASTIAN zrANI DE EERRANTI, or LoNDoN,'ENcLAND.

l STE AM-TURBINE l a To all whom itf'may concern:

Be it known that I, SEBASTIAN ZIANI DE FERRANTI, a subject ofthe King of Great Britain and Ireland, and resident of 31 Lynd-l 5 hurst road, Hampstead, London, N. W.,

England, have inventedcertain new and useh ful Im rovements in Steam-Turbines, (for which Patent in Great Britain, No. 124,781 ,bearing date November 11, 1902, and No. 7,685, bearing date April 2, 1903; in Germany, bearing date May 29, 1903, and Austria-Hungary, bearing date April'21, 1903,) of which the following is a specification.

' My ingention relates to turbine heat engines employing the ex ansion of a comparatively readily condensi le elastic fiuid, such as steam, ether, oil vapor, ammonia or the I have found by calculation and experiment that in such elastic fluid turbine engines, utilizing the expansion of the elastic fiuid, a very great gain 1n the total efiiciency takes place if, after superheating, the expansion be causedntg take place isothermally instead'of adiabatically, as is the usual practice. I find also that there is some gain in the total efficiency if the fluid is expanded isothermally instead of adiabatically without initial superheat. I believe the gain due to the isothermal instead of adiabatic expansion 'in the two LJcases mentioned is to` be attributed partly to thermo-dynamic and partly to mechanical causes, though the proprtional gain due to each cause probably plained he/reafter. #M It is Well lfnown that in elastic fluid heat engines, turbine or otherwise, 1 lb. of the iluid vapor need onl take awa `a quantity of heat to the con enser equa to H2, the latent heat ofl the fluid at the pressure of exhaust. Most engines throw away to the condenser an amount, -per pound of fluid, less than this, depending on the wetness of the free from external coo g and with the usual limits of pressure, the amount varies between 85% and 90% ofthis. In engines or turbines not expanding down to the ressure of the condenser or' of the atmosp ere into which they exhaust, a feed ,heater or ,regenerator must be used to reduce the loss to a minimum. Such a re enerator takes R units of heat i' er pound of uid from the exhaus? and trans ers l them t0 thfeed of the genera or or boiler.

Specification of Letters Patent. v Application filed October 31, 1903. Serial Nip-179,407.

have made application for Letters` iers greatly in the two cases, as will be ex-` iuid at the end of expjlnsion. Inan engine- Patented July 7, 1908.

As an approximation in the case of known engines we may take it that H2 units are tlirow'n away to the condenser per pound 'of fluid and if H1 is the heat given to the pound of fluid initiall by the fuel, then Hl-H2 isl the amount o 'heat turned into work, and H,H2

total heat received by the fluid per cycle.Y

For a given exhaust pressure, H2 is xed,

the efficiency of the engine or turf l bine 1so that H1=H R units, Where H is the and the thermal efficiency can only be increased by making H1 greater. done by increasing the ressure of thel fluid vapor, and the practica limit in this direction has probably been reached. It requires a very great increase in the pressure to increase H,L even by a small amount. Another way is to heat the fluid vapor out of contact with its liquid Without increasing its pressure, that 1s, to .superheat it. the practical limit is soon, reached, since the materials we can use will not stand a much higher temperature than 400 C. Superheating u to 400 C., does ynot increase the' value of 1 very much.

Here again,l

This may be 'lol NOW my invention relates to a method of increasin H,l very reatly without passing beyond t e practical limits of temperature and pressure. The principle which it approximately realizes is that of adding enough heat during the expansion of the fluid to kee its temperature constant; this is called isot ermal expansion. In this case, however,- 1 lb. of fluid at the end of expansion is superheated and contains more than H2 units of heat; but this can be reduced to H2 units by the lise of a regenerator which transfers some heat to' the vworking fiuid. The way `in which `I approximately realize isothermal expansion is to expand the fiuid vapor in several stages in a turbine or engine, reheating the fluid vapor between some or all of the stages in reheaters up to the initialftemperature ofthe vapor. The vapor the number of sta es in which the fluid.

vapor is reheated, t e more nearly does its temperature keep to a high constant value l ,and the more nearly is isothermal expansion realized; the greater also is the quantity of lea turned into work, per unit of working If the fluid is superheated before isothermal expansion, it in this way takes in a large quantity of heat at the highest temperature and consequently there is a large increase in the thermodynamic efficiency compared with the case of superheated steam expanding adiabatically. Isothermal y expansion of the superheated iiuid also has the advanta e of entirely preventing con- 'bine and will get wetter and Wetter until exhausted. This condensed vapor largely increasesthe friction of the turbine Wheels revolving in it and absorbs considerable power; so that isothermal expansion, apart from the thermodynamic gain over adiabatic expansion pointed out above, also gives rise to a mechanical gain due to the lessened friction. If the fiuid is not superheated before expansion, the thermodynamic gain of isothermal overv adiabatic expansion is probabl small, as the temperature at which heat 1s taken in during the expansion is but little higher than the average temperature of feedheating and evaporation and consequently this heat is not capable of being converted into work with any greatly increased efficiency. The indirect mechanical advantages d'ue to the prevention of condensation are however greater in this case, as without,

' superheating the fluid is wet throughout'if adiabatic expansion is employed. Therefore, eitherA w1thl or without initial superheat,

'the employment of isothermal instead of adiabatic expansion gives rise to a large increase in the total eiciency.

My invention therefore consists broadly in reheating the elastic fluid emplo ed in a multiple expansion turbine engine etween the various stages of expansion in such a Way that the total expansion more or less closely approximates to true isothermal exansion, whereby an amount of heat greatly 1n excess ofthe whole of the available heat contained initially in the elastic fluid used maybe added and efficiently utilized and a great increase in economy attained.

My invention further consists: (l) in employing a regenerator in conjunction with an lsothermal expansion turbine engine to extract and utilize the heat from the outflowing exhaust; (2) in various combinations of isoseasis l thermal expansion engines with superheaters, 1re-heaters, boilers, regenerators and waterheaters, whereby. economical utilization of fuel may be obtained; and (3) in arranging the elements which formy the complete power generator employing practically isothermal expansion, all in one machine, combined so as to save heat loss. It will be seen that an isothermal expansion power generator, ac-

cording to my invention, may be constructed of a greater or less number of elements, accordingtothe degree of increased economy which is aimed at.

Referring to the accompanying drawings Fi re 1 shows the general arrangement in e evation of a complete installation of lant having fire-heated superheaters and reeaters, Figs. 2, 3 and 4 being corresponding sections on the lines XX, YY and ZZ respectively of Fig.`1. Fig. 5 shows a modification of the arrangement of Fig. 1 and Fig 6 an arrangement adapted to the case of a Lancashire or other flue boiler. Fig. 7 shows another general arrangement in which superheated steam is employed in the reheaters.; Fig. 8 is a detail view showing an alternative arrangement of the reheater coils; Fig. 9 is a modification of the arrangement of the re-heaters of Fig. 7, while Figs. 10 and 11 Y, show diagrammatically other methods of reheating b meansk of superheated steam. Fig. 12 sliows a longitudinal section of the turbine as a whole.

I will describe my invention as a plied in one modification in what I consi er its best form, viz., with all the elements combined together in one machine so as to obtain the highest economy. I will assume the turbine 1s to use steam as the medium of expansion and that it is desired to employl thou it will be seen that any condensible elastic Huid may be used and that'a compound turbine of any of the other wellnown types may be employed. I therefore construct (Figs. 1 to 4) a compound or multi le stage impact steam turbine; a, in a well nown manner but I separate each stage in such a wa that I canfpass the steam exhausting from t e first stage through a reheater delivering into the inlet of the second stage and from its exhaust to a second reheater and so on, re-heating after each stage expansion to the finalv exhaust. I arrange the turbine, a, on a horizontal shaft and provide the re-heaters below the turbine body. These re-heaters,b, c, are tube elements situated in a combustion iue, d, which' also contains the boiler, 62,11, superheater, h, i, and water heater, c, l, e ements.

a comlpound turbine of the impact type, al-

In connection with the exhaust passage, f

m, of the turbine, I arran ea coil regenerator, n, so as to extract t e heat from the exhaust which comes from the turbine at a temperature approaching the maximum temof the furnace.

perature lof the cycle; I arrange the water supply to the inlet of this regenerator to come froml the condenser, u, or from the hot well by way of the pipe, o, and I connect the regenerator outlet, p, which is nearest to the turbine, preferabl to the water heater ele-v traction of heat from the gases of combustion,

which are produced and burned from on'e end I may also employ coal-dust as the furnace combustible. 1

Beneath or around the furnace f'lue, carrying the boiler, superheater, reheater and water heater elements,l I prefer to construct fiues to carry the products of combustion to the chimney, .8, and through these waste gas f fiues I carry 1ron air ducts, t, which convey theair supply to the furnace in a direction preferably counter to the `flow of the waste gases, thus forming anmair regenerator and obtaining hot air for the fuel combustion.

According to a modification, as shown in Fig. A5, the length of piping between the turbine and reheaters is reduced to a minimum, the regenerator being removed from the osition shown in Fig. 1 and placed be on the fiue heated elements. Fig. 5 also s ows another form of reheater consisting in one or more heaters from which tubes depend. Fig.. 6 shows an arrangement of parts in which a Lancashire or other flue boiler is used instead of the water; tube boilers of Fig. 1.

The same letters are used in the last two figures as in Fig. 1 to denote similar parts.

According to another modification shown in Figs. 7, 8 and 9, instead of direct fire-heating of the reheaters, I arrange them to be heated.k indirectly by superheated steam. Thus in Fig. 7, the steam generator is shown at 2,Yprov1ded .with steam drums, 3, from which the steam is led through the superheater, 4, in the uptake.

After superheating, the steam divides into two parts, oneKV al't t e 1pipe, 6, and the other lpart passing to the reeaters, 7, by way of t e pipe, 8. In the example shown the turbine 1s provided with five reheaters, the superheated steam from the pipe, 8, passing through them in arallel. A pump, 9, is provided to return t e condensed steam issuing through the pipe, 25, from the re-heaters to the boiler through the pipe, 10, feed water heater, 26andpipe, 27.

he arrangement I prefer in the re-heaters is to conduct the steam from the turbine after the first stage of expansion through the pipe, 11, to the bottom of the first re-heater and then upwards in a direction counterto that of the superheated steam through the coil, 12, and back to theturbine. This action is repeated after each stage of expansion in the turbine, the steam finallI .passing through the exhaust pi e, 13, to't e regenerator, 14. It will be un erstood that as the figureis merely diagrammatic, the proportions of reheater coils and the other parts are not those which would be adopted in practice. An alternative arrangement of the re-heater coils is shown in Fig. 8, steam from the turbine being led to the bottom of the re-heater through the pipe, 15, whence it returns through t e pipe, 16, meanwhile traveling in an opposite direction to that of the superheated steam which enters the top of the reheater through the pipe, 17, and flows through the coil, 1 8, to its outlet, after which its path back to the boiler is as before.

Referring again to Fig. 7, the steam from the turbine passes throu h-the regenerator to the condenser, 19, whic may be ofthe jet condensing type, .supplied with cooling water through the pipe, 2Q, and provided with an air pump, 21. Another pum' 22, which may if convenient, be worke ofi the air "pump, 21, serves to pass a part of the outflow om the condenser through the regenerator coils, 28, whence it passes on and joins the condensed steam .from the re-heaters. The combined steam may then be pumped through the economizer or feed-water heater, 26, placed in the uptake and returned to the boiler, thus completing thek cycle.

In Fig. 8, is shown another 'arrangement of the reheaters;, the coils, 12, through which the steam from the turbine passes, are in this case arranged in one large compartment, 24,

superheated steam enterin through the pipe, 8, las before and leaving a terzcondensation,

by the pipe, 25, after which its course is as described above.

Instead of dividing the superheated steam into two parts according to the methods of Figs. 7 an 9, I may use the following system. Steam from the generator, 2, (see Fig. 10) is led throu h the pipe, '29, to the superheater, 30; after eing superheated in the coils, 31, it asses through the pipe, 32, direct to the reeaters, 33, which are, in this case, preferablyof the type shown in Fig. .8. The steam then returns through the pipe', 34, to the superheater, when it is re-superheated by passing through the coils, 35, 36, after which it goes direct to the turbine by way of the pi e, 37.

In ig. 11, I have shown yet another method of 'conducting the su erheated steam through the re heaters. team from the generator, 2, passes as before, through the pipe, 29, to the coils, 31,of the superheater,

' 30; it then passes through the pipe, 38, to

thereheaters, 39. Thesevare of the same general type as those shown in Fig. 8, except that the coils are divided into upper and lower sets. The steam after passing through the upper coils, 40, 40, of the re-heaters returns through the pipe, 41, to the coils, 35, 36, of the superheater and after issuing thence divides into two parts, the one art passing through1 the pipe, 42,v to the turtlfiney and the other'part b way of the ipe `43, through the lower coi s, 44, 44, of t e reheaters, the lwater of condensation beingrreturned by the pump, 45, to the generator, either directly through the ipe, 46, or indirectly through a feed water eater such as is shown at 26, Fig.- 7 v C With regard to the turbine'itself, as above mentioned, it is of the compound or multiple stage expansion impact type. Each stage of the expansion thus forms a turbine of what is known as the Laval type. Eacli pairV of fixed and moving elements of this Nturbine also constitutes a complete turbine in which the drop of pressure is arranged totake place in the jets of the fixed element only. The jet chamber of the second-stage is supplied through the first re-heater, and here again the drop of pressure takesplace in the fixed from the last of these being preferably exjets of the second stage, and so on throughv the various stages of expansionin the turbine down to the exhaust.

It will be seen that by means of the reheaters provided at each stage of expansion, the temperature of the turbine is maintained practically uniform from end to end and the exhaust steam will pass from the turbine practically at the temperature at which it, at each stage passes, to the reheater, the larger the number of stages employed, the nearer being the approach to isothermal expansion. The exhaust steam then delivers through a passage, in which is situated the generator for the extraction of its heat and then into the condenser, which is preferably a jet or ejector condenser em*- ploying practicall air freed water.

It will be seen t at various elements of complete isothermal expansion power generator may be omitted without departing from,

my invention, although of course, the omission of these elements will involve a less econpmical production of power. For. exam- (a) The regenerator may be omitted and in this case the isothermal expansion is only carried over a -portion of the range the remainder of the expansion being effected adiabatically; reheating should, however, be carried to such a stage as to insure a sli htly superheated exhaust. I find it possib e to secure a considerableagain in economy by the luse of only three reheating stages, the steam panded adiabatically andv passed through the regenerator.

(b) It will be obvious that the air regenerator may be omitted and also the condenser,

although such omissions smaller advantage.

According tfine form of turbine (see Fig. 12) l construct'the casing of a number of sections, to 57,A bolted steam-tight'to each other in such amanner as to provide a set of chambers, 58 to 65, in which the turbinewheels revolve.

Taking the section of casing,l 52, as an example for the purposes of description, and referring to Fig. 12, it consists of the following parts: A disk 66, which may be dished as required, is provided at its center with a circular aperture through which the main shaft, 67, of the turbine passes, the steam tightness ofthe shaft through said 'aperture being secured by means of suitable packings, containedV within the \packing casing, 68. The disk, 66, connects at its circumference with the short cylindrical ring of metal, 69, which forms the circumferential wall of the wheel chamber, 60; extending for about twothirds ofthe distance round the outside of the ring, 69, in a second artial ring, 7 0, connected to the inner ring y means of the web will involve a \or partition, 71; this web, together with@ that in the adjacent section of the casing and the inner and outer rings, forms a passage 60a, into which the steam, on its return from a reheatei/ passes by way of the opening, 60", Fig. 8. These steam passages are numbered in the figures to correspond with the wheel chamber to which they pass steam and are distinguished by the suflix a; similarly the openmgs giving access to these assages and to which the connections from' t e re-heaters lleadbearthesuflix. TheWeb,71,at several points, 72, is hollowed so as to form ports, 60, (extending into the disk 66) through which the steam may pass to the nozzles, the steam tothe ports being controlled by piston valves 60d. The piston valves controlling corres onding ports 1n the different sections are al mounted on one spindle such as 73 in Fig. 12.

The exhaust from any wheel chamber, for example No. 59, takes lace by way of a recess, 59'5, formed in the ower art of the disk portion of the section, 52, of t e turbine cas-` lng, the steam thus entering the chamber, 591. and thence passing through the opening 59h, to its appropriate reheater. The same system of suffixes is used for, the reference letters as described above.

The last section, 57, .is somewhat different in the particular turbine illustrated," since no reheater isv provided between the wheel chambers, 64 and 65; thus the exhaust from the chamber, 64, passes byway ofthe recess, 64", in the disk portion of section, 57 `direct vin the casing sections concerned in the manner described in the last/paragraph.

To the high pressure section of the casing, y 50 a cover, 75, is secured containing an annular pass e, 58a, `towhich steam passes through t e opening, 58h, the steam being distributed by way of the valves, 58d, to the wheel-chamber, "58./The*section, 50, is also provided with a stuin box and gland,- 76,

through which the sha t, 67, passes to the outside of the turbine; At the low pressure end of the turbinefa cover Vis/provided which `lubrication is rendered more difficult.

however, several great advantages. One of L btainmg increased economy in working conforms an exhaust passage,- 77, for the steam from the wheel chamber, 65, this cover also suporting a stuiiing-box and gland, 78.

' though the sections and covers3`ofthe casing have for convenience been tlesciibed as though formed each of one piece, they are in reality formed 'in halves, as shown in the end views and bolted together.

The turbine shaft, 67, is supported beyond the ends ofthe casing in bearings, 79 and 80, preferably provided with a spherical portion, 81, so as to admit 'of a certain amount of selfadjustment; these bearings are mounted on suitable pedestals, 82, tied together by connecting ieces, 83, the weight of the casing being tagen by brackets, 84.

It will be seen that an isothermal expansion turbine of my new type has to work under the maximum temperature of the cycle. This has the disadvantage .that

It has these is that the steam can be maintained practically dry throughout the whole range of ex ansion. This fact has great influence in re ucing the frictional losses in the tur- `bine.v Agalim no great variations of temer'ature exist in the turbine, the whole turadiabatic.

' the same temperature.

ine casing'being practically maintained at The diiiiculties ordinarily occurring in steam turbines through unequal expansion due to une ual heating of the different parts of the tur ine practi cally disappear. f

Although I have used the termr isothermal expansion in setting forth my invention I am, nevertheless, aware that the expansion throu h each stage' is actually closely T e effect ofthe reheaters taken in conjunction with the adiabatic expansion, is, however, to cause the resultant expansion line to cross and re-cross an isothermal line drawn at about the mean temperature of the re-heats, said' expansion line thus approximating to such an isothermal line more or.

said uid ina series o sta-ges and re less closely according to the number of reheats and it is in this sense that I wish the words isothermal expansion to be construed, both in the body of the specification and in the following claims.

A form of apparatus for carrying out the process claimedherein, is made the subject of another application by me, Serial Number 249253, dated March 9/05., n, i

Having ifow described my invention, what I claim as new and desire to secure by Letters "154 Patent is 1 1. In elastic iiuid turbines, the method of obtaining increased economy in workingconsisting in expanding'the luid .in a series of stages and reheating between stages so'as 80' to render the expansionapproximately isothermal.

2. In elastic luid turbines the method of obtaining increased econom in working consistingdn superheating the uid and expanding said iiuid in a series of stages Vand reheating between stages so as to render the expansion approximately isothermal.

3. In elastic iiuid turbines the method of obtaining increased economy in working consisting in expanding the iiuid inaT series of stages, reheating between stages so as to render the expansion a proximately isothermal and passing the exaust iiuid through a regenerator so as to restore heat to thexworking fluid. Y 1

4. In elastic iuid turbines the method of obtaining increased economy in working consistin in superheatin the fluid; exphanding said uid in a series o stages and re eating between stages so as to render the expansionap roximately isothermal' andpassing the ex aust fluid through a regenerator so as to restore heat to the working fluid.

5. In elastic iiuid turbines, `the method of sisting in expandingjthe iiuid in a series of stages and reheatingto the initial temperature between'said stages, thereby rendering the expansion a proximately isothermal.

` 6. In elastic uidv turbines, the method of obtaining increased economy in working cons istin in superheatin the fluid; ex anding said uid in a series o stages and rdiieatingto the initial temperature of. superheat be- 11.'l tween said stages, thereby rendering the eX- pansion a proximately isothermal.

' 7. In e astic iuid turbines, the method of obtaining increased economy inworking consisting in expanding the fluid in a series of stages and reheatin between stages, the mean temperatures o the re-heats being substantially identical.

8. In elastic iiuid turbines, the method of obtaining increased economy in working consistin in superheatin thefluid; exyinding eatin between stages, the fluid being superheate throughout/fits expansion and the mean tem i tures of the re heats being substantially eratures of the re-heats being substantially identical and passing the exhaust fluid ldentieai. through' a regenerator so as to restore heat 9. Y In eiastic fluid turbines, the method of to the Working fluid. 5 obtaining increased economy in Working con- In Witness whereof I have hereunto set my l5 sisting in superheating the fluid at a point of hand in presence of two Witnesses. the cycle, expanding said fluid after said SEBASTIAN ZIANI DE FERRANTI, superheating 1n a series of stages to such an Witnesses: y extent only at each stage as to keep it dry7 re- ALBERT E. PARKER,'

10 heating between stages, the mean tempera-r BERTRAM I-I. MATTHEWS;

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