US1110799A - Regulating mixed-pressure turbines. - Google Patents

Description

B. KRMER.

REGULATING MIXED PRESSURE TURBINES.

APPLICATION FILED FEB. 1'5, 1911.

Patented Sept. 15, 1914..

2 SHEETS-SHEET L.

Witnesses: Inventor:

Bernhard Krmer;

Hisoqttorneg B. KRMER. RBGULATING MIXED PRESSURE TURBINBS. AYPLIGATION FILED PEBJS, 1911.

Patented Spt. 15,1914,-

a sumsgum n,

gins to be shut ofi. Conversely, when the valve moves upward from its lowest position, the exhaust steam valve will be entirely opened before the high-pressure steam 5 can flow into'the pipe 10.

The valve is moved by a hydraulic motor comprising a cylinder and a piston 16,

the latter being connected to the valve by a piston rod 17. Tubes 18 and 19 convey vhydraulic pressure to the ends of said cylinder for the purpose of driving the piston to and fro. These tubes are connected to a valve chest 20 in which is a pilot valve 21, preferably of the piston type as shown, controlling the admission to said tubes of fluid pressure supplied to the valve chest through the pipes 22, and exhausting therefrom through the pipe 23. The valve 21 is shown in-its mid position, to which it has been moved after admitting pressure to the tube 18 and the lower end of the cylinder 15 to force up the piston 16and the valve 1 to the position shown. The valve chest 20 is supported on a spring 24 inclosed between caps 25 and 26, the latter being mounted on the hub of a bevel gear 27 rotatably journaled on a stem 28. On the upper cap 25 is a collar 29 swiveled tothe valve chest so that the collar,.caps and spring are free to -rotate with the` bevel gear. Fly-balls 30 are connected by pivoted links 31 to the hub of the gear and to the collar 29. The gear is drivenV by a pinion 32 rotating in synchronism with the turbine. The' stem 33 of the pilot valve is screw-threaded to receive a nut 34 by means of which one can adjust the tension'of a spring 35 abutting between said nut and the top of the valveehest. The upper end of said stem `is pivoted at 36 to a floating lever 37, one end of which is pivotally connected to the piston rod 17. The other end of said lever is .pivoted to the movable core 38 of a stationary solenoid 39, through whichis shunted a portion of the line current of rthe turbine driven generator 40, the terminals of the solenoid being connected across a suitable resistance 39a. The core 38 has an extension 41 which rests upon a cup 42 secured to the-lower end of a helical spring 43 which tends to lift said core against the downward pull of the solenoid.

In the drawing, the line current is assumed to be at a maximum,- so that the core is in its lowest position. The operation of these parts is as follows: Under the conditions shown the turbine is running at normal speed and carrying full load. If this load decreases, the turbine will tend to run faster. This means that the ily-balls will exert more cehntrifugal force, so that the valve-chest 2O will be pulled downward, the pilot valve being held stationary for the moment bythe lever 37. The result of this relative movement of the chest and valve is to admit fluid pressure into the tube 19 from the lower tube 22 and connectthe tube 18 with the exhaust pipeV 23. The piston 16 at once moves the regulating valve 1 downward to shut olf the live steam more or less and slow. down the turbine. The downward movement of the piston rod also acts to restore the pilot valve to a n'iidway position so as to shut olf both tribes 18 and 19 and stop the valve 1. This is accomplished by the lever 37, which fulcru'ms on its point of attachment to the core of the soleiioid. Now when the turbine slows down owing to the throttling of the steam by the valve 1, the spring overpowers the ily-balls and pushes up the valve chest. Since the pilot valve is held by the piston rod 17 and the lever 37 in a lower position than before, this action of the valve chest would tend to open the pipe 18 to the fluid pressure. To-prevent this, and to lift the pilot valve sufficiently to l-:eep the pipes 1S and 19 closed, the solenoid 39 also comes. into play as the turbine speed decreases The decrease in load referred to above means a reduction in the line current, so that the solenoidv is weakened, and its spring 43 is permitted to lift the core 38, thus raising the lever, which fulcrums on its point of attachment to 'the piston` rod 17. This acts to lift the pilot valve sufficiently to'keep up with the upward movement of the valve chest 20 due Atao-.the slowing of the centrifugal governor, and thus the. valve 1 is maintained in its new position. A

By adjusting the nut 34, the tension of the spring 35 is varied, which results in varying 100 the effective action of the regulating device by varying the centrifugal force necessary to effect a .relative movement othe casing 2O and the valve 21. AIt also serves to regulate the position of the valve in said casing v105 when the parts are at rest, so that the mouths of the pipes 1`8vand 19 can be exactly covered.

In the modification shown inI Fig. 2, the centrifugalA speed-responsive device shown 110 in Fig. 1l is replaced by a solenoid tl connected across the termina-ls of the generator, so as to constitute a device responsive to chauves in potential in the-current developed by the generator. In all other respects the 115,` parts are constructed and arranged as in Fig. 1. Inasmuch as the potential of the current varies directly with the speed of the generator, the increase or decrease in speed, due to changes ,in load, will be eilectually 120 met by this device equally as well as by the centrifugal governor.

Fig. 3 is a diagramillustrating graphically the operation of my improved regulators under different conditions. The line 125 I represents thepath of the steam valve 1; the line II the path of the casing 20 and pilot valve 21, and the line III the path of the core of the solenoid 39. On the line I the section o 7) represents the travel of the 130 sent the two points at 'which the centrifugal regulator 3 0 has its highestand lowest number of revolutions respectively, orfthe core of the potential coil 44 is drawn in most or least. On line III, the vpoints u and 'u' indicate the lowest position and'the highest, respectively, of the core o f thecurrent lsole` noid 39'; that is, the points at which the lload 'of the distribution system acting on the- -solenoid is greatest or smallest the lines passing through pointsson said three lines represent positions of thel'ever37:

The steam vvalve 1 may occupy a position w with purely exhaust drive, or a positions@ corresponding to purely live steam drive or mixed pressure drive.' In passing from one drive to the other, the valvehas thus to.

travelover 'the path 'w at.

rlfhe method .of operation' of the device is as follows: If the load regulator con' ceived to be held Afast atv any point y, and the speed regulator. acts upon the regulating valve inthe ordinary way, then the regulatsleeve has to pass ovei',for he movement ofthe valve; from tot 1, the lpath 80'- r. For a. shifting. of' the` valve between the points fw and ac,.that is, for passing from one' kindl of driveto the other the path to be traversed -would accordingly be-3,;-tx2 AV case Where the load regulator might be held East at the point y Would be where the ina-f chine Worksalone in a distribution systemr and the load remains unchanged. Actually however'the point y is not heldfastby the load regulator. There occur on the contrary, vchanges in the load of the system, jso that the point y' is shifted. This shifting is such Vthat the regulating valve l is raised or love'-4 e'red in the same way as by the 'regulator 30 or 44, so rthat either ofI said regulators `is supplemented in its action by' the load regulator 39 'and a condition of stability results.

AIf, however, the lmachine is operating in a system, wherein for `the sake of simplicity a three-phase system will first be assumed, iii which the speed of all the machines is directly dependent one upon the otl'1er,theii` held fast at a given load,sin'ce the speed is the speed regulator may beassiimecl' to be prescribed by the system. In direct-current operation moreover' all the machines in circuit are likewise dependent one `upon the other as -to speed, since at the smallest load the potential of the current establishes .the number of revolutions. Thus if the speed regulator 30 or 4l is regarded as fixed at a point z, then the regulator 39 must move the end of the lever 37 over the path yy', thevchange in the number'of revolutions,'and in path of the regulating valve'l 'being i1f-.i-. Accorr'lingly a change of load on the turbogenerator takes place in. passing from the one method of driving tothe other, which must be eqiialized by theremaining nia- 7 0 chine's connected in `parallel. The effort 'v will be to keep this change of load as small as possible, that is, thepathyuv should. Abe only :i1-small fraction ofthe total path afin-a condition which may-be readily. secured by suitable lever-transmission conditions,`

^ I The abovementioned change in the load distribution of the 'systemcauses. in turn :i

thc example se ected, that is, in passing from 'exhaust' drive o live-steam or 1ni1n2 .d'p,les sure drive, a reduction 1nv the number of revolutions ivill take `place With'a'vdecrease in -the' work performed. This decrease inf the number of revolutions has the resiilt'that the speed regulator 30 or 44-as`sists the process ofzregulation, so that thestability necessary for'the entire system pieserved,jand thel dilerencein the vvork 'performances of the l90 combined machine is not so great as it would have become without the `va'riation'of .the .number of revolutions." i This variation of the number of revolutions is lsmaller in proportion to the difference-,between the loads corresponding to the points Yuand '11.. In accordance with the`fprovisions of the patent statutes. have described `the princi f ple of operatiouof my invention, together` with the apparatus Which-I noxv consider to .100. represent the. best embodiment thereof; but I des`ireto have it u'nde'rf'stood'that the ap! paratus shown is only illustrative, and that .the invention can-'be-carried. out by other means.-

What I claim as new and desir'eto secure bv Letters Patent-ot the United States, is,-

Y L1. The. combination vvith a prime mover.

land valve mechanism forcontrblling the admission of motive fluid thepriine mover.' 110 "of a fluid-,actuated motor for actuating the "alve mechanism, a valve for controlling the supplgl-Y of motive fluid to the motor` a movablegseat for the.. valve..'a device responsive to thesneed of the prime mover, and a de- .115 vice responsiveto the. ldriven load Aon the ,prime mover, one of said devices being connected to thevalve and the other to the sea t.

f 2. T he combination with aiprime mover, and valve mechanism for 'controlling the ad- 120 mission of motive'fluid to the prime mover,

lof a fluid-actuated motor for. actuating the valve mechanism, a 4valve for Vcontrolling the supply` oi motive fluid to .the motor, a movf,v

ableported sea't for the valve, means for' 125' adjusting ,the valveand seat relative to each other, a device responsive to the speed of the prime mover, a' devicev responsive to the driven load on the prime mover, one of Said devices being the`valve and the .tvveen the other valve member and the other other to the seat, and means-for preventing overtravel of the motor.

3. In combination, a prime mover, an electric generator driven by any prime mover, valve mechanism for controlling the admission of motive fluid to the prime mover, a. fluid-actuated motor for actuating the valve mechanism, a valve for controlling the supply of motive fluid to the motor, a movable ported-seat for the valve, a device responsive to the speed -of the prime mover, and a device responsive to the current generated by the electric generator, one of said devices being connected to the valve and the other to the seat.

4. In combination, an electric generator, :i mixed pressure turbine driving the generator and having a valve mechanism for controlling the flow of Aexhaust and live steam to said turbine, a .motor for actuating said valve mechanism, a pilot valve for saidmotor, a casingfor said pilot valve adapted to be moved in response to changes in the speed of said turbine, a current coil in circuit With said generator and having a movable core, and a lever pivoted to a moving part of said motor, to said pilot valve and to the core of said current coil.

l 5. The combination with a prime mover, and valve mechanism orcontrolling the admission of motive fluid to the prime mover, of a fluid-actuated motor for actuating the `valve mechanism, a valve mechanism for the motor comprising a valve member and a movable Seat member, a device responsive to the speed of the prime mover, -a device responsive to the driven load on the prime mover, means connecting one of the valve members to a moving part of the motor iand to one of said devices, and a. connection bedevice.

6. The combination with a prime mover, and valve mechanism for controlling the admission of motive fluid to the prime mover, of a fluid-actuated motor for actuating the valve mechanism, a valve controlling the supply of motive fluid to the motor, a movable seat for the valve, a device responsive tothe speed of the prime mover, a device responsive to the driven load on the prime mover, one of 'said devices being connected to the seat andthe other to the valve, and means actuated by a moving part of the motor for preventing overtravel of said motor.

7. In combination, a prime mover, an electric generator driven by the prime mover,

valve mechanism for controlling the admisn i sion of motive fluid to the prime mover, a fluid-actuated motor for actuatingthe valve mecha ism, a valve for controlling the supply of motive iuid to the motor, a movable ported seat for the valve, a speed responsive device for moving the seat, a device responsive to the current generated by the generator, and lever means connected to a moving part of the motor, the valve and the current I responsive device.

8. The combination with a mixed pressure turbo-generator, of valve mechanism for controlling the admission of live and exhaust steam to the turbine, a. fluid-actuated motor for actuating the valve mechanism, a valvel controlling the supply of motive fluid to the motor, a movable seat for the valve, a spring connection between the valve and seat, a device responsive to. the speed .of the turbine, a device responsive to the current generated by the generator, one device being connected to the seat and the other to the valve, and means for preventing overtravel of the motor.

9. The combination with a. mixed pressure turbo-generator, of valve mechanism for controlling the suppl;T of exhaust and live steam to the turbine, a fluid-actuated'mctor for actuating the valve mechanism, a valveA for controlling the'supplvv of motive fluid to the motor, a movable ported seat for the valve, a stem for the valve, an 'adjustable abutment on the stern, a springarranged between the abutment 'and the seat, a speed responsive device connected to the seat, a device responsive to the current generated by the generator, and lever means connecting the current responsive device and a moving part'of the motor to the valve stem.

10. The combination with a prime mover, and valve mechanism for controlling the admission of motive fluid to the prime mover, of a fluid actuated motor for actuating the valve mechanism, a valve for controlling thesupply of motive fluid to the motor, amovable seat for the valve, and a plurality of governing devices for the prime mover, one

of which is connectedto the valve and the other to the movable seat so that either may be moved relative to the other in response to variations in the operating conditions of the prime mover.

In Witness whereof, I have hereunto setv my hand this 26th day or' January, 1911.

BERNHARD KRMER. i

Witnesses ERNST USBERKE, OSCAR EBERTH.

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