US1117306A - Governing mechanism for steam-turbines. - Google Patents

Description

0. BANNER. y GOVBRNING MBCHANISM FOR STEAM TURBINES.

APPLICATION FILED APRJO, 1914.

Patented Nov. 17, 1914.

2 SHEETS-SHEET 1.

O. BANNER. GOVBRNING ldlGI'ANISMA POR STEAM TURBINES.

' APPLICATION FILED Anglo, 1914. 1,117,306, Patented Nov. 17, 1914,

2 SHEETS-SHEET 2.

UNTE.

FCE.

OTTO BANNER, OF EASTON, PENNSYLVANIA, ASSIGNOR T INGERSOLL-RAND COM,- PNY, 0F JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

GOVERNING- MECHANTSM FOR STEAM-TURBINES.

Specification-of Letters Patent.

Patented Nev. 17,1914

Application led April 10, 1914. Serial No. 830,843.

:a turbine which will be simple in construction and which will operate eiiiciently through a large range of loads.

A further object is to provide a regulating mechanism for turbines of this class which will be positive vand powerful in its operation without undue complication, such regulating mechanism being suitable for any turbine wherein it is desired to admit the operating fluid successively to separate nozzles or groups of nozzles.

With these objects in view, a turbine and regulating mechanism has been devised, a practical embodiment of which is shown in the accompanying drawings, in which,

Figure 1 shows a longitudinal 'section .of the machine, Fig. 2 shows an end elevation, partly broken away to show partial sections on the lines 2-2 and 23-2'1 of Fig. 1, Fig.

3 shows a transverse section on the line 3-3 through the regulating vmeans on a larger scale, and Fig. 1 is a detail showing the construction of the pilot valve operating levers.

The turbine', as shown, comprises a casing 1 in one end of which is placed a high pressure wheel 2 the discharge of which passes through a series of low pressure stages comprising diaphragms 3, et, 5 and 6 and low pressure wheels 7, S, 9 and 10. rl`he discharge of the high pressure wheel 2 passes through the low pressure stages in series. the diaphragms 3, i and 5 being provided with nozzle passages 11., 12, and 13 which extend preferably around the whole periphery of the diaphragms giving full injection to the 4low pressure wheels 7, 8 and 9. In the diaphragm 6 the nozzles 11, which receive the discharge from the preceding stage. only extend partly around the periphery of the diaphragm, the remaining portion of the diaphragm on its inletside being covered by a steam chamber 15 .from which\a\sepa rate set ot nozzles 16 which may or may `not be of the same angle and. expansion as-the nozzles 14, lead through the diaphragm 6 and discharge against the bladesrof the wheel l0. This steam chamber 15 may be in one or more divisions and is here shown as divided into two parts 17 and 18, to which steam is furnished from the discharge of the high pressure wheel 2-through conduits 19 and 20 by means of valve mechanism, further to be described.

Steam is admitted to the high pressure wheel through one or more groups of expansion nozzles, here shown as consisting of four groupsl 21, 22, 23 and 21, which receive high pressure steam from a boiler or other source of supply, (not shown), by means of the inlet pipe 25. The admission ofsteam to the various groups of high pressure nozzles and the sections of the 'low pressure steam chamber feeding the nozzles l16, is etl'ected in the following manner: Mounted on'the end of the turbine, casing is a valve chest 26 which is divided into a high pressure steam chest 27 intoI which the high pressure inlet pipe 25 opens and a low pressure steam chest 28 which is supplied with low pressure steam from the discharge of the high pressure wheel by means of a conduit 29 leading from the casing of the turbine. In the lower wall of the steam chest 27 areinlet openings 30, 31, 32 and 33 for admitting steam separately and respectively to the nozzle groups 21, 22, 23 and 24, while in the lower wall ot' the low pressure steam chest 28 are inlet openings 31 and 35 foradmitting low pressure steam separately to by- pass conduits 19 and 20. These inlet passages are controlled independently by valves 36, 3T, 38, 39, 40 and -11 which have stems attached to motor pistons 4:2, 43, 411, 45, 46 and 4T which are of similar construction and adapted to have a limited movement in a series of cylinders formed in a cylinder casing L18 on top of the valve chest 26.- These pistons are operated by the pressure of fluid such as oil, the admission and discharge of which is controlled in the following manner, it being 'necessary to4 describe only, in detail, piston 4T as the others are entirely similar. der pressure is admitted to a port 19 in the side of the cylinder by means -of a pipe 50 Oil or other Huid un`- from a source, not shown. The port- 49 is in communication with a bore l which eX- tends axially from one end of the piston to the other, by means of a passage 52 which is always in communication with the port 49 no matter what position the piston is in.

' Above the passage 52 is an annular chamber 53 oi2 larger diameter than the bore l from which. a passage 5lleads to the bottom o'l the cylinder. The upper end of thc bore 5l is in communication with the openupper end of the cylinder hy means lof ports 55. Sliding inthe bore 5l is a pilot valve 56 which has an r operating stem 5T which projects from the upper end of the cylinder and tivo heads or controlling portions, an upper head 5S which controls the admis sion and discharge of the oil from the lower part-of the cylinder and a lower head 59 which serves as aguide and also to prevent oil from `passing through the open lower .end ot' the here 5l to Ithe lower end Vof thev cylinder. Movement of the pilot valve upwardly admits oil through the. passage 52 to the lower end of the cylinder through lthe passage 54 forcing thepiston upwardly while downward movement of the pilot valve 'allows the passage 5,4 to be put into communication'v with the upper end of the bore 5l and permitsv the oil in the' lower part of the cylinder to escape into the upper casing permitting a spring 60, whichpresses against the top othepiston 47, to move it downwardly. lThe oil escaping from the top of the acylinders ows to the bottoml ot the casing and-escapes by an outlet tube, (not arranged however that the pilot valve can move considerably lfarther 4either up or down, than the pison 47 without having any further 'etlect on piston, this being lim the cylinder.-

As stated before, the pistons 42, 43, 44,

and i6 are precisely similarv in construction and operation to the piston 47, as are also the pilot valves 6l, 62,'(33, 6l and 65 which control them. ln order that these pist-'ons and th'eir valves may not operatev ject in the same direction trom the rock shaft. Pivoted to the end of each of these "levers is a connecting rod 65, which, in turn, is pivotally'connccted with the stem otite respective pilot valve. A rocking motion in accordance'ivith the load on the turbine is given to the shift 66 by means ot speed The pilot valve 56 and the inlet, and exhaust portsI of the piston 47 are soy the movement onthe ted by the .length of' innesco pilot valves 6l, 6i, 63 and 6l are given a successivel)- greater length so that the controlling portions of these valves come into etlective positions in relation to the controlling ports ot the pistons at successive points in the movement oi' the rock shaft 66. This operation is made possible by the construction described above,` which allows these pilot valves to have a considerable travel in either direction after its piston has stopped moving without affecting the yposit-ion (if the piston so that pilot valve 64,

tor instance, can move a considerable distance upward, as shown in Fig, 3, without.

having any etect on the movement ofV its piston. lt 'is evident that the same result couldbe accomplished by having the pilot valve stems of the same lengt-h and the levers 6T set at different angleson the rock shaft.

As shown in Fig. 3, the four high pressure pistons have their pilot valve stems of sucha length that .they open successively under varying conditions ot' load, while pilot -valves and 56 have their stems of the Inv o der;-

same length as pilot val`vesi63- and 64 so the low .pressur Valves 40 and 41 are'opf erated simultaneously/'and to the same extent a's-the-.last two high pressure valves 38 and 39. Under normal conditions of operation, therefore, live-steam will be admitted -in accordance with the .load through high pressure inlet openings 30 and 3l only. `Under overload conditions, Valves 32E-and 39 will beI opened admitting and 2li, while at the same time, low pressure valves 40 and l1 will he opened allowing low pressure steam to enter the by-pass conduits 19 and Q0, thus successively relieving' the excess pressure due to the largeexcess of high pressure steam admitted to the high pressure wheel, progressively in accordance with the excess of high pressure steam admitted. the loiv pressure .vheels through the nozzles ll is maintained at a pressure at which the low pressure wheels will work efficiently vvhile the excess steam is lay-passed to the chambers 17 and 1S and utilized for effective work by passing through the nozzles 16 to the last low pressure wheel 10. y

T he operation ofthe turbine and its reguating mechanism will he evident from the above description. Assuming that the turbine is operating under no load and hence at its maximum speed, .all the levers 67 and hence the pilot valve 61 will be substantially` high pressure vsteam to high pressure nozzle groups Q3V y In this way the steam passing to` -in the position shown for the pilot valve 63 vwith the inlet openingO partly closed and all' the other inlet openings completely closed. As the load' on the turbine increases, thelevers 67 will movel upwardly, the pilot valve .61" first opening .the -valve 30 to its fullest extent and the other pilot valves successively openingtheir inletvalves as their opera-ting lheads 58 successively come into 'operative relation with the passages 54.

' [The turbine here shown 'is constructed to v -operateei'ciently both above and below the normal load, that is,"the 4load at'vvhich the turbine isdesigned to give itsmaximum ehiciency. In the pr'esentcase, for m'stance,

the lturbine wouldprobably be designed to 'have its eatest eiciency when the valves '36 and 3 are open as far-asfthey can be,

without valve 38'being ope As shown Fig: 3, the regulating mech-v .anism' is in a posltion to cover.'a partial b overload, the valves' 36 and 37 being raisedl to their fullest'extent while the valves 38` and 40 are partially raised admitting a certain amount of steam to 'the nozzles 23, and 'to the by-pass conduit 19 and part of noz- "Although the turbine .and regulating I mechanism are here shownas -having four i ent that the number of nozzle groups or the groups of high pressurenozzles and two oups4 of low pressure nozzles, it is evi- "number of nozzles in each' group may be vvawithout departing fromlthe invention,

js'falso may. the number of blades or bla'de f 'ro'ws in each stage andthe amount of inj'eotion of each, and furthermore, although the regulation of the :steam is 'effected by "a certain. definite regulating mechanism, any

sort of device forregulating the amount of steam admitted to the turbine in accordance with the load thereon may be substituted fwithout *inventionfor the present device.

Furthermore, tinstead of regulating the nowof steam tothe by-pass conduits directlyby the load, the steam may be admitted to these by valves opening when the pressure in the steam chest 28 reaches a predetermined tion andother formsand modiifations are quantity, and: itl is to be understood that the present showing and description discloses only one v spec'ziied modification of my `invenincluded iiithe spirit and scope of the in 1. In a steam turbine, a high pressure stage', a series-of low'pressure stages each having stage nozzles receiving the discharge from the preceding stage, a ste-amv chamber coveringpart of the stage; nozzles of one of' said lovv pressurestages and 'a `by-pass`conduit connecting said'steam chamber with .the exhaust of said' high pressure stage. v

2.'In"`a steam turbine, a high pressure stage, a of lovvpressure stages4 each steam" to said 4higtli 'having stage nozzles receiving the discharge from the preceding stage, a steamrc'hamber covering part of the stage nozzles' 0f one of said low pressure stages, a by pass conduit connecting said st eam chamber with the exhaust of said highpressurestage and governing means controlled by the load to open l said bv pass conduit under' overload'conditions.

high pressure wheel, and means depending onA the -load for reo'ulatingthe admission of pressurev wheel and to said by pass conduit.

4, In a steam turbine, a high pressurestage, av series'of low pressure stages, one lof said low pressure stages havingl a set of nozzles receiving the discharge from the preceding stage and a second set of nozzles receiving fluid from a by. pass conduit leading from' the discharge of said high pressure wheel, a series of valves for .admitting fluid to said-high pressure stage, a valve for admitting fluid to said by pass conduit, and regulating mechanism governed by the load for successively ,opening said high pressure valves and for openingv said by pass valve .simultaneously vwith a late opening high Y v 100 pressure valve.

5. In a steam turbine, a high pressurel stage, a series of low pressure stages, a by pass conduit leading from the discharge of said high pressure stage to one of the low.

Vpressure stages, a valve controlling the adso duit leading from the discharge of said mission to said high pressure stage, a valve controlling 4'the admissionv to said by pass conduit, and Ymeans controlled'by tlie load'` for controlling said high pressure valve and'.

for opening said by pass valve under overload conditions.

6. Ina steam turbine, a highfpressure stage, al series of low pressure stages, a'bypass conduit-leading from the discharge of said high pressure stage to one ofthe low pressure stages. avalve controlling the ad mission to said'high pressure stage, a'valve controlling the admission to said by 'pass conduit, and means for controllingl said high pressure vvalve and for opening -said by pass valve under'highload conditions.

7. In ai steam turb1ne,'a high -pressurelv stage, a series of low pressure stages, a by passconduit leading from the ldischarge ot' saidhigh pressure stage to one of the low .pressure stages, a seriesof valves\control7 ling the admission of fluid tosaid high pressure stage, a valve for controlling admission to said by pass conduit, and means controlled by the load for successlvely opening seid high presenze valves fm' opening seid by pass valve smuisenem 1' valves, motore fo? `opel veives,

valves fel eontreng Said perte Suid pilot z;

Vabres being capable of movement pee seid oelrbs in eher reoton W'twut aeetng the poei'ibons of Said meters, un element mevable with Ehe 'leali on. the tu bine and means connecting Said pile'; vevee with snif?, A

movable ei

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