US2009419A - Dual fluid governing system - Google Patents

Description

July 30, 1935. A. F. SCHWENDNER DUAL FLUID GOVERNING SYSTEM Filed June '7, 1934 INVENTOR NTHONY F'. SCHWENDNER.

WITNESSES:

ATTORNEY Patented July 30, 1935 UNITED STATES;

DUAL FLUID GOVERNING Immu i.

Anthony F. Schwendner, Essington, Pat, assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 7, 19?.4, se n No. '129,3'l2

' 8 Claims. (Cl; 264-14) My invention relates to governing apparatus for steam turbines and the like and it has for an object to provide apparatus of this character con structed and arranged to utilize non-inflammable liquid for the operation of parts, such as the admission valve and the throttle valve, subject to high temperatures so that fire hazard may be minimized.

The trend of power plant design has been in the direction of higher and higher temperatures and pressures; and temperatures have alreadybeen reached in practice which make the use of conventional oil relay and pressure responsive devices hazardous'where employed in connection with admission of throttle valves, for, in case of breakage or leakage, ignition of oil is likely to occur. To avoid this hazard, it is an object of the present invention to provide non-inflammable liquid to secure operation of the valves or high temperature parts, the turbine developing a controlling force whose magnitude depends upon its speed and the controlling force providing noninflammable liquid under pressure dependent on the magnitude of the controlling force and which is .used to control the admission of steam to the turbine. V

More particularly, I provide a dual-liquid control system wherein the primary liquid is oil under pressure varying as a function of the turbine speed and operating a transformer to secure the secondary or non-inflammable liquid under pressure depending upon the oil pressure and operating the admission or governor valve. Also, noninflammable liquid is used, instead of oil under pressure, for holding the throttle valve open against the force of the usual spring or biasing means. Accordingly, a further object ofmy invention is to provide a pressure control system for the valves of a turbine wherein non-inflammable liquid is applied to the high temperature parts, such as the governor or admission valve and, the throttle valve. 7 V f A further object of my invention is to provide a dual-fluid governing system wherein oil under pressure is developed as a function of the speed of the prime mover and used in atransformer,

supplied with now-inflammable liquid through an orifice from a suitable source, the passageway means supplying liquid to the throttle valve to hold the latter open aganst the force of suitable biasingmeans and the'pressure in the passageway means being subject to sudden release upon operation of theemergency governor, whereby thethrottlevalve may close in the usual way under the influence of its biasing means.

A further object of my invention is to provide a turbine having an emergency governor, an admission valve, and a throttle valve with a noninfiammable fluid pressure system for operating both the admission and the throttle valves, the turbine developing oil under pressure varying as a .function of its speed and the oil under pressure being utilized by a transformer'to secure non-inflammable liquid under pressure depending upon theoil pressure and the non-inflammable liquid being supplied from the transformer to the admissionvalve to control the operation of the latter; the throttle valve being normally held open against the force of-suitable biasing means by non-inflammable liquid supplied to passageway means through an orifice from the high pressure source; and, in case of operation of the emergency governor, both the pressure holding the throttle valve open being suddenly released and the transformed non-inflammable liquid under pressure going to theadmission valve being released, whereby sudden closure of the throttle valve andrclosure of the admission valve are secured. 1

These and other. objects are effected by my invention as will be apparent from the following description and claims taken in connection ,with the'ac'co'mpanying drawing, forming a part of this application, in which:

. The single figure is a diagrammatic view show- .ing my improved dual liquid'turbine control system. I

Referring .to the drawing more in detail, I show a turbine Ill including a casing or stator H and a spindle or rotor l2;

zThe turbine is provided with one or more ad- =mission valves l3 operatedby servo-motors it.

Each servo-motor includes an operating cylinder l5 and an operating piston I 6, admission and exhaust of I motive fluid to the operating cylinder .being secured by a suitable pilot valve H.

The throttle valve l8 supplies steam to the admission valve or valves IS, the throttle valve be- .ing providedwith 'a rod l9 to which is attached a piston 20 arranged in a cylinder 2| with a spring 22.arranged above the. piston. The throttle valve is held open against the force of the spring 22 by suitable fluid pressure means as will be hereinafter more fully described.

The turbine stator and spindle elements I and i2 provide oil impeller apparatus, indicated generally at 23, for supplying oil under pressure which variessubstantially as the square of the speed of the turbine. "The impeller includes a runner 24 carried by the spindle and supplying oil under pressure to the annular chamber 25 "ranged therein, the abutment having its outer which supplies oil through the orifice 26 to the passage or conduit 21. One end of the passage 21.

communicates with an annular chamber 2 8 formed in the stator structure I and covered by the spindle structure, suitable packing elements ture to restrict leakage. A-diagonal slot-or passage 29 is formed in the spindle structure, one end of the passage communicating with the annular chamber and the other-end communicating with the drain. As pointed out in the application of Bryant, SerialNo. 728,257, filed May 31, 1934, this type of construction provides for a centrifugally controlled resistance opposing the escape of oil from the passage or conduit 21, whereby the pressure in the latter varies as the square of the speed ofthe turbine. The pressure so developed'in this passage is utilized by apparatus hereinafter described.

The turbine drives an emergency governor, at 38, including the conventional pin 3|, which flies out in response to the attainment of a predetermined overspeed to operate the trigger mechanism 32 to release the valve 33, the latter relieving pressure within an orifice passage system with the effects hereinafter pointed out.

A non-inflammable liquidreservoir is shown, at 35, from which non-inflammable liquid is pumped by a pump 36 to the high-pressure supply line or system 31, the drainage of non-inflammable liquid being returned to the reservoir by the drainage conduits or system'indicated generally at 38. a

The impeller apparatus, at 23, supplies oil to the passage?! and operates.- to-maintain the pressure in the latter substantially as the square of the speed of theturbine, the passage 21 supassigned to the Westinghouse Electric & Manufacturing Company. Thextransformer includes a housing or body 40 having an upper chamber 4| and acylinder 42. The cylinder is provided with a pressure supply port 43 connected to the I high pressure supply line 31, and an exhaust connection 44 leading into the chamber 45, which communicates with the drainage system 38.1 The cylinder also has a secondary'or transformed pressure supply port 46 arrangedbetween the pressure supply port and theexhaust connection and connected to the secondary -or transformed pressure line 41 communicating with the servomotor or motors I4. A piston valve 48 is arranged in'the' cylindenthe piston valve having piston portions normally justlapping the exhaust connection 44 and. the pressure supply port '33, respectively. I

With upward movement of the'pist'on' valve,

the transformed or secondary pressure line is placed in communication with the exhaust connection, thereby reducing the secondary or transformed pressure; and, with downward movement of the piston valve, the secondary transformed pressure line 41 is placed in communicationwith the high pressure passage 31, thereby increasing the secondary or transformed pressure.

The upper chamber 4| has an abutment 5| aredge connected tothe lower end of an upper sylphon 53, and the upper end of the sylphon 53 is attached to the interior wall of the chamber 4|. A secohdsylphon 54, of smaller diameter than the sylphon 53, is connected'at its upper end to the abutment and at its lower end to the bottom wall of the chamber 4|. Thus, it will be seen,

-.tha t the sylphons 53 and 54 and the abutment 5| cooperate with the body construction 40 to define'a fluid-tight chamber 52 to which oil under primary pressure is supplied by the impeller apparatus, at 23. 1 a

As the lower sylphon 54 is of smaller diameter than the upper sylphon 53, it will beapparent that the abutment 5| provides a downwardlyfacing annular piston area 55 which is subject to the primary or impeller pressure, such pressure tending to cause the abutment to move upwardly. The force of the primary or impeller pressure acting on the abutment is-opposed by suitable spring means 56 arranged in the chamber 4| the'spring means having its lower end engaging the abutment 5| and having its upper end engaged by'a follower 51 whose position is varied by suitable speed changer mechanism 58.

' The upper end of the piston valve 48 has a thrust bearing portion at 59 engaging the-lower surface of the abutment 5|, the upper portion of the piston valve beingarranged within the space defined by the lower sylphon 54, whereby the features affording abutting engagement of the abutment 5| and of the piston valve'are sealed in a fluid-tight manner from the primary or oil pressure chamber 52, thereby preventing any possible leakage of oil from the latter chamber.

The piston valve 48 is provided with a secondary piston area 6| closing the expansible chamber 6| connected by a passage 62 with the secondary pressure port 46 and the secondary or transformed pressure passage 41. The passage 52has'an orifice 63, preferably provided by a needle valve 64. Also, an air chamber 55 communicates with the expansible chamber. As more particularly disclosed and claimed in my application,

aforesaid, these features contribute to more stable operation-of the governing apparatus and also give to it an anticipating 'efiect, that is, violent fluctuations in transformed or secondary pressure, and consequent hunting of the apparatus, 'areavoidedand the apparatus, due';to the cooperation of the orifice and an airchamber, is responsive to high rates of load change so-as to secure appropriate admission of steam to the turbine for the new load without substantial change, in speed thereof.

7 To avoid static friction, the piston valve 48 has spinning motion imparted thereto preferably by turbine means including a bucket wheel 55 car- 'ried' by the valve and motivated by a jet 66'supplied from the high-pressure line 31.

Preferably, the transformer, at 39, operates as crease in load, 'the abutment-5| moves upwardly against the force of the spring 56, the piston valve 48 following the motion of the abutment-as pressure is applied to the secondary piston area or face 68, and the secondary or transformed pressure line 4'! is placed in communication with the exhaust, thereby bringing about reduction in secondary or transformed pressure, this reduction continuing until the force due thereto and acting on the secondary piston area or face 60 is reduced sufliciently to compensate for the increase in primary pressure force acting on the abutment 5|, whereupon the spring means 56 will be effective to restore the piston valve to neutral or cut-off position; and, on the other hand, with an increase in load and decrease in speed, the primary pressure is reduced resulting in downward movement of the pilot valve and consequent increase in transformed or secondary pressure, the increase in the latter continuing until the force thereof acting on the secondary piston face area 60 compensates for the decrease in' the primary fluid pressure force whereupon, as before, the pilot valve is restored to neutral cut-off position.

Changes in transformed or secondary pressure brought about in the manner just indicated result in adjustments of the steam admission valve to control the admission of steam to the turbine suitably to the load. With an increase in load and a decrease in primary oil pressure, the secondary transformed pressure increases and operates the servo-motor or motors to increase the admission of steam; and, with a decrease in load, resulting in an increase in primary oil pressure, the secondary pressure is decreased, the latter operating on the servo-motor or motors to decrease the steam admission. e

The servo-motor or motors M are constructed and'arranged to provide for closure of the admission valve or valves in case of drop of the secondary transformed pressure below a predetermined amount, closure being assured due tospring means 61 arranged in the servo-motor or motors above the pistons IS.

The servo-motors l4 may be of any suitable type. By way of example, I show the piston l6 hollowed out to provide a pilot valve cylinder 10 for the pilot valve I! pressed downwardly by a scale spring 12 and moved upwardly by transformed or secondary pressure acting on the lower piston face 13 and supplied from the chamber 14 connected to the secondary or transformed pres- "sure system 41.

As shown, the scale spring 12 acts compressively between the upper end of the pilot valve and the cover of the servo-motor housing. Thus, it will be seen that the lower piston face of the pilot valve l1 and the spring 12 provide means responsive to a range of pressures so as to secure operation of the servo-motor sufficiently to move the steam admission valve from closed to wide open position or vice versa. Assuming a change in pressure supplied by the transformed pressure system 41, this is accompanied by movement of the pilot valve l1 until such time as equilibrium isestablished between the forces of the spring and of the transformed pressure. The operating piston I6 follows the motion of the pilot valve until the neutral or cut-off position is established, whereupon the operating piston and the admission valve will be held in position until such time as a further change in transformed pressure ocpressure, the passages 15 and 18 formed in the operating piston are placed in communication and liquid under high pressure from the high pressure system is supplied below the operating piston to cause the latter to follow the pilot valve,

thereby moving the associated steam valve in an opening direction, and. this movement of the operating piston continuing relatively to the pilot valve 11 until communication'between the passages 15 and 16 is interrupted. With decrease in secondary or transformed pressure, the pilot valve moves downwardly, placing the passage 15 and IT in communication, thereby allowing fluid to pass from the space below the operating piston l6 to the space thereabove and the operating piston following the pilot valve under influence of the spring 61; and this downward movement of the operating piston relatively to the pilot valve will continue until communication between the passages 15 and TI is interrupted. In case of failure of transformed pressure or decline thereof below a predetermined amount, the servomotor spring 61 closes the associated admission valve |3.

From the foregoing, it will be apparent that I have devised a unitary control system for a turbinewherein fire hazard, heretofore arising onv account of oil-operated devices associated'with the steam valves, is avoided, oil only being used.

as the primary pressure medium to control the operation of the transformer and non-inflammable liquid, such as chlorinated diphenyl, commonly known as araclor, being used throughout other parts of the system. The oil line 2'I.is indicated by solid arrows and all non-inflammable liquid lines are indicated by dash arrows to distinguish them from the oil line. Not only is noninflammable liquid under transformed pressure supplied to the pilot valves of the admission valve I servo-motors to secure actuation of the latter .by non-inflammable liquid supplied from. the high pressure system, but the latter supplies the orifice system normally effective to hold the throttle valve open and to hold the trip valve in such a position that the transformed or secondary presorifice passage system 8| having branches 82, 83

and 84 leading to the emergency governor valve 33, to the throttle valve cylinder 2| and to the trip valve, at 85, which normally closes the release passage 86 communicating with the transformed. or secondary pressure line 41. The trip valve, at 85, includes a piston 81 arranged in a cylinder 88, a spring 89 acting on the piston in such a direction as to tend to open the passage 88, that is, to place the latter in communication with the drain system. Fluid under pressure supplied 'by the branch 84 of the orifice system acts on the 1 piston 81 against the force of the spring 89 to to close the passage 86.

Also, as shown, the trip valve, at 85, normally allows free flow of high-pressure non-inflammable liquid from the system. 31. to the high pressure port 43 of the transformer governor, at 39.

From the structure so far described, it will be apparent that, upon release of pressure in the orifice system 8l .supplied by the orifice 80,

dueto opening of the valve 33 in consequence g of operation of the'emergency governor, the pres sure in the system 8L will be suddenly reduced, thereby resulting in closure of the throttle valve [8 and movementof the trip valve, at 85, to place the release passage 86 incommunication with the drain, thereby resulting in rapid reduction in secondary or transformed pressure and consequent closure of the admission valve. Also, the supply of high pressure non-inflammable liquid to the transformer is interrupted.

WhileI have shown my invention in one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What Iclaim is:

1. In a prime mover having a steam supply means including an admission valve, apparatus driven by the turbine fordeveloping pressure of oil which varies as a function of the prime mover speed, a source of non-inflammable liquid under pressure, a pressure transformer including means responsive to developed oil pressure for securing transformed pressure of non-inflammable liquid dependent thereon, said developed oil pressure responsive means including a fluid-tight expansible chamber to which oil under developed pressure is supplied, and means contiguous to the admission valve and responsive to transformed pressure for controlling the admission valve, said last-named means being so located with respect to the'steam supply means that leakage from the former would likely contact with the latter.

2. The combination with a turbine having steam supply means provided with an admission valve, of means for developing oil under pressure whichvaries as a function of the turbine speed, a source of non-inflammable liquid under pressure, a pressure transformer including means responsive to oil pressure for securing transformed pressure of non-inflammable liquid, said pressure responsive means including a piston abutment and sylphon means defining a liquidtight chamber preventing the leakage of oil or the admixture thereof with non-inflammable liquid, and means arranged above the steam supply means and responsive to transformed pressure of non-inflammable liquid for controlling the admission valve.

3. The combination with a turbine having steam supply means provided with an admission valve and pressure-responsive means arranged above the supply means for controlling the valve, of means for developing oil under pressure which varies as a function of the turbine speed; a source of non-inflammable liquid under pressure; a housing providing a chamber and a cylinder; a pair of sylphons joined to the chamber walls and to a piston abutment and defining a pressure chamber connected to the oil pressure developing means; said cylinder having an inlet port connected to said source of non-inflammable liquid under pressure, an exhaust connection and a transformed pressure port; means providing a passage for supplying non-inflammable liquid from the transformed pressure port to the admission valve pressureresponsive means; a piston valve for controlling communication of the transformed pressure connection with the pressure supply port or with the exhaust connection; abutment means between the piston valve and said abutment and including a thrust bearing; means providing a piston face on the piston valve; a passage for supplying non-inflammableliquid under transformed pressure to said piston face; and means for imparting spinning. motion to the piston valve.

4. The combination with a turbine having steam supply means provided with an admission valve, of a source of non-inflammable liquid under pressure; a servo-motor arranged above the steam supply means and including a pilot valve for controlling the admission of non-inflammable liquid from said source to the servo-motor and. the exhaust of such liquid from the latter to secure operation thereof to vary the extent of opening of the admission valve; means responsive to a range of pressures to actuate the pilot valve for operation of the servo-motor to open or to close the admission valve to the extent required by the load; means operated by the turbine for developing oil under pressure varying as a function of the turbine speed; a movable abutment having a primary piston area; bellows means cooperating with the abutment to define a liquid-tight chamber enclosed in part by the primary piston area; means for supplying oil under developedpressure to said chamber; a cylinder having an inlet port in communication with said source of non-inflammable liquid under pressure, an exhaust connection, and a secondary or transformed pressure port; a conduit connecting the secondary port to the pilot valve pressure-responsive means; a piston valve for establishing communication of the secondary pressure port either with theinlet port or with the exhaust connection to secure variation in secondary or transformed pressure. in said conduit; abutment means between the pilot valve and said movable abutment and including a thrust bearing; means providing a secondary piston area on the piston valve and disposed so that pressure applied thereto tends to cause the piston valve to move toward the movable abutment; means providing for the application of non-inflammable liquid under transformed or secondary pressure to the secondary piston area; and means for imparting spinning motion to the piston valve. 7

5. The combination with a turbine having steam supply means provided with an admission valve, of a source of non-inflammable liquid under pressure; a servo-motor arranged above the steam supply means and including a pilot valve for controlling the admission of non-inflammable liquid from said source to the servomotor and the exhaust of such liquid from the latter to secure operation thereof to vary the extent of opening of the admission valve; means responsive to a range of pressures to actuate the pilot valve for operation of the servo-motor to .open or to close the admission valve to the extent required by the load; means operated by the turbine for developing oil under pressure varying as a function of the turbine speed; a movable abutment having a primary piston area; bellows means cooperating with the abutment to define a liquid tight chamber-enclosed in part by the primary piston area; means for supplying oil under developed pressure to said chamber;

. a cylinder having an inlet port in communication with said source of non-inflammable liquid under pressure, an exhaust connection, and a secondary or transformed pressure port; a conduit connecting the secondary port to the pilot valve pressure-responsive means; a piston valve for establishing communication of the secondary presj'sure port either with the inlet port or with the exhaust connection to secure variation in secondary or transformed pressure in said conduit; abutment means between the pilot valve and said movable abutment and including a thrust bearing; means providing a secondary piston area on the piston valve and disposed so that pressure applied thereto tends to cause the piston valve to move toward the movable abutment; means providing for the application of non-inflammable liquid under transformed or secondary pressure to the secondary piston area; and means utilizing non-inflammable liquid as motive fluid to impart spinning motion to the piston valve and including a turbine whose rotor is carried directly by the latter.

6. The combination with a turbine having an admission valve and means for biasing the admission valve in a closing direction, of means for developing oil under pressure which varies as a function of the turbine speed, a source of non-inflammable liquid under pressure, a pressure transformer responsive to oil pressure for securing transformed pressure of non-inflammable liquid, means responsive to transformed pressure of non-inflammable liquid for controlling the admission valve, and means responsive to overspeeding of the turbine for relieving the transformed pressure so that said biasing means may be effective to close the admission valve.

7. In a turbine having an admission valve and a throttle valve, pressure responsive means for controlling the admission valve; means for biasing the admission valve to closed position; means driven by the turbine for developing pressure of oil which varies as a function of the turbine speed; a source of non-inflammable liquid under pressure; a transformer responsive to oil pressure for securing transformed pressure of noninflammable liquid, the transformed pressure depending upon the oil pressure; a passage for supplying non-inflammable liquid under transformed pressure to said pressure responsive means; a trip valve; said trip valve, when open, releasing the transformed pressure in said supply passage so that the biasing means may close the admission valve and, when closed, maintaining the pressure in the passage; pressure-responsive means acting against biasing means to hold the trip valve closed; an orifice passage system for supplying non-inflammable liquid to the throttle valve to hold the latter open against the force of its biasing means and for supplying such liquid to the pressure-responsive means of the trip valve to hold the latter closed; an orifice for supplying non-inflammable liquid from said source to the orifice passage system; and turbine overspeed responsive means for releasing the pressure in said orifice passage system.

8. The combination with a turbine having an admission valve, a throttle valve and an emergency governor; of means for developing oil under pressure which varies as a function of the speed of the turbine; a source of'non-inflammable liquid under pressure; a pressure transformer utilizing oil pressure to secure transformed pressure of non-inflammable liquid derived from said source; a servo-motor for moving the admission valve and including an operating cylinder and a pilot valve; a passageway for supplying non-inflammable liquid under transformed pressure to the pilot valve to render the latter effective to supply non-inflammable liquid from said source to and exhaust non-inflammable liquid from the operating cylinder; a relief valve for said passageway; means for biasing the relief valve to open position, pressure-responsive means for holding the relief valve closed against the force of the biasing means; said servo-motor including means for moving the admission valve to closed position when the pressure in said passageway drops below a predetermined minimum; pressureresponsive means for holding the throttle valve open against the force of biasing means; an orifice passage system supplied with non-inflammable liquid through an orifice and connected to said relief valve and throttle valve pressure responsive means; and means responsive to operation of the emergency governor to relieve the pressure in said orifice passage system to secure opening of said relief valve to bring about closure of the admission valve and to render the biasing means of the throttle valve effective to close the latter.

ANTHONY F. SCHWENDNER.

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