US801357A - Governing mechanism for turbines. - Google Patents

Description

No. 801,357. PATENTED OCT. 10, 1905` J. G. CALLAN. GOVERNING MBCHANISM FOR TURBINES.

APPLICATION FILED MAR.30, 1905.

Witnesses:

UNTTED STATES ATENT OElEllClE.

JOHN Cr. CALLAN, OF LYNN, MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

GOVERNING NIECHANISNI FOR TURBINES.

Specification of Letters Patent.

Patented Oct. 10, 1905.

Application filed March 30, 1905. Serial No, 252,807.

To all whom it may concer-71,:

Be it known that l, JOHN Gr, CALLAN, a citizen of the United States, residing at Lynn, in the county of'Essex, State of Massachusetts, have invented certain new and useful Improvements in Governing Mechanism for Turbines, of which the following is a specification.

The present invention has for its object to improve the construction and operation of the mechanism employed for governing turbines or other motors.

My invention comprises a regulating mechanism which includes a primary means for determining the supply of steam or other motive fluid delivered to a turbine, with secondary means for automatically apportioning this steam whatever its amount among a plurality of nozzles in such manner as to use it with the maximum possible efficiency or to approximate this condition as nearly as ossible. The primary means maybe contro ed by a speed-responsive device, by hand, electromagnetically, or otherwise and may in its simplest and preferred form consist of a throttle of any approved design. lts function is simply to determine the amount of motive fluid supplied without in any way afecting its distribution to the nozzles. The distributing or secondary means have primarily the function of keeping the minimum number of nozzles open at a given time which will afford passage for the quantity of steam determined in the manner just described, this' condition being demanded by considerations of economy in that type of turbine in which the motive fluid is fed to the wheel by a plurality of nozzles. It will be noted that the varying back pressure consequent on the action of the distributing or secondary device will affect the functioning of the throttle if this be used as a device for fixing the supply of steam, and hence affect the speed-load characteristic. On the other hand, this distributing or secondary dev ice may be used under conditions where this reaction does not occur-as, for example, in a low-pressure turbine usingto best possible advantage all the exhaust of a reciprocating engine or high-` pressure turbine.

ln carrying out my invention one, two, ory

fluid-discharging devices. These valves may control the admission of fluid initially to the turbine or motor, or they may control the passage of fluid between any two or more stages of a multistage machine, or valves may be provided for both functions. Under normal conditions the valves open one after the other to admit fluid to thenozzles and close in reverse order to cut it off. Each valve is provided with a motor for opening and closing it which responds to changes in pressure of the motive fluid. These motors are of such a size or character and are so arranged that one valve opens at a definite predetermined pressure, a second valve at an increased pressure, and so on. Conversely, one motor closes its valve and then another, and so on. The motors should also be of such a character as to cause the valves to open sharply and promptly, so that the time during which they are close enough to their seats to cause cutting is extremely small. l prefer to operate these valves by diaphragms, since the latter possess certain advantages in the way of freedom from packing, absence of lubrication, &c. When the valves are diaphragm-actuated, the valve-stems move without sliding friction, and no frictional elements of any kind interfere with the action of the apparatus. This, among other things,.permits of a close approximation to boiler-pressure in the inlet-chamber before the first valve and afterward each succeeding valve is brought into action, thereby increasing the average efficiency of the machine. Undercertain conditions pistons may be substituted for the diaphragms; but l consider this to be less advantageous, since it would be necessary to lubricate and pack them, and they would leak to a certain extent.

It is preferable to provide each valve with two diaphragms or e uivalent devices of different areas, the smal er one being subjected to the inlet or boiler pressure and the larger one to the pressure within some portion of the turbine, usually the steam-chest of the controlled nozzles. In other words, the pressure within the turbine tends to open the valves successively, and the inlet or boiler pressure acts as a weight therefor and tends to close them successively. In addition to and cooperating with the diaphragm-actuated admission-valves a throttle-valve is provided which is moved by a suitable speedin demand for power.

responsive device driven directly or indirectly by the turbine-shaft. This valve by its action varies the pressure to which the larger diaphragms are subjected, and hence controls-the action of the Afluid-pressure-actuated admission-valves. lt is obvious that the load conditions will not always be satisfied by a given number of open and closed admission-valvesthat is to say, two valves may not admit enough fluid, while three valves will admit too much. The throttlevalve will take care of these intermediate load values by assuming different positions for different loads, and in this manner it is possible to obtain a perfectly gradual increment of motive iiuid for a gradual increase This obviates any tendency to a sudden increase in speed, especially in small machines, on the opening of an additional valve. It is therefore possible to take advantage of the gain in economy due to the governing by progressive addition of nozzle-sections without incurring short life for the valves, as would be the case if the governing were solely by their progressive action, or causing irregularities in speed, as would occur with the successive opening and closing of the governor-controlled valves communicating directly with the steam or motive-fluid passage. The use of a throttlevalve also decreases the number of times that the admission-valves operate, thereby reducing the wear thereon. The throttlevalve normally opens more or less before each admission or nozzle valve and closes more or less before each of said valves. In other words, it anticipates both the opening and closing of the admission-valves. 'lhevalve at which all throttling occurs is cheap, simple in construction, easily replaced, and by its construction inherently adapted for throttling service and is therefore long-lived under conditions of operation. By using the boiler-pressure to Weight the admissionvalves any reduction in pressure acts equally to reduce the tendency for the admissionvalves to open and close. For example, with low boiler-pressure, as with normal, all of the valves may be brought into action when the load requirements demand it. This is of further value in starting, since with the steam. throttled by a hand-valve in the main supply-pipe and the throttle or governor-controlled valve wide open, as it would be at low speeds, the valves will all be wide open, allowing the maximum acceleration ln the accomp anying drawings, which illustrate one embodiment of my invention, Figure l is aview, partially in section and partially in side elevation, of a turbine. Fig. 2

is a partial end elevation showing the location. of the admission-valves, and Fig. 3 is a detail sectional view of a device for adjusting the percentage of boiler-pressure at which the valves will open.

1 represents the casing of the turbine con taining the bucket-wheel 2, having one or more rows of peripheral buckets 3. l/Vhere two or more rows of wheel-buckets are used, stationary intermediate buckets 4 are provided, which receive steam or other motive fluid from one row of wheel-buckets and discharge it against the next. The motive Vfluid is discharged against the wheel-buckets by one or more nozzles or other devices 5. The nozzle preferably, but not necessarily, coniprises a number of closely-associated discharge-passages having the same cross-section and angle of discharge. ln the present illustration of my invention'four of these nozzles are provided, three of which have diaphragm-actuated valves, the fourth being always open,

The invention is shown in connection with a et or impact type of turbine; but it is not to be construed as being limited thereto. Fluid is admitted to the turbine by the valvecontrolled conduit 6, the latter' communieating with the passage or chamber 7 formed in the head of the wheel-casing. Located at some suitable point between the conduit and the nozzle is a spring-closed shut-oil. or emergency valve 8, arranged to be tripped by a speed-responsive device when the speed of the bucket-wheel exceeds a definite amount. Situated in the admission-passage 7 at a convenient point between the shut-off valve 8 and the nozzle or nozzles is a throttling-valve 9, which is moved by the speed-responsive device l0. rlhe valve is of the piston type and by its reciprocating movement varies the pressure of the Afluid in chamber 7. It is shown in full-open position, as is also the shut-off valve.

The motive fluid is admitted to the nozzles by valves 1l, of which three are shown; but the number can be varied as desired. The valves and their operating-motors being similar in construction, a description of one of them will suffice. The valve is attached to a stem l2, and the latter is ailixed to the low`V` pressure diaphragm 13 and the high-pressure diaphragm 14:. On the valve-stein. is a stop l5, which limits the movement of the valve-stein to the left. The stop should be so arranged that it does not cut off the admission of steam to the diaphragm-chamber. The chamber between the diaphragms is connected to atmosphere or other exhaust by the conduit 15a. The lov-pressure diaphragm is held against its seat by a nut 16, and the latter acts as a seat for the high-pressure diaphragm. rlhe high-pressure diaphragm is held in position by a nut 1.7, the latter being externally threaded to receive the cap 1.8. The end of the valve-stem may be provided with means, such as a nut or nuts, for cutting a valve out of service when for any reason it becomes desirable. rlhe permanent opening of one of the admission- IOO IOS

valves would not seriously interfere with the governing, since the throttle-valve 9 controls the speed regardless of the number of valves open, providing only that this number is not reduced by some accident which leaves one or more permanently shut. The chamber 19 on the left of the high-pressure diaphragm is connected by the conduit 2O` with the inlet or boiler pressure. The passage of fluid through this conduit may be controlled by the valve 21. I may design the high-pressure diaphragm 14 to be subjected to the full boiler-pressure or a certain fraction thereof.`

The operation of any one of the valves, assuming it to be closed, as shown, is as follows: There is tending to open the valve the more or less throttled pressure in the chamber 7 multiplied by the area of the diaphragm 13 and a constant. Tending to close the valve is the same throttled pressure multiplied by the area of the valve 11 plus the pressure inthe inlet-pipe 6 multiplied by the area of the diaphragm 14 and a constant. l/Vith pressures substantially equal in chambers 7 and 19 the pressure on diaphragm 13 will overcome that on diaphragm 14 and valve 11 and the latter will open. lt will therefore be seen that when the turbine is below speed, with the throttle-valve 9 wide open and the hand-operated throttle-valve in the conduit 6 either open or partially closed, the admission-valveswill all be open and all of the nozzle-sections in action. This will be the condition at starting and until a further increase in speed causes the valve to close. l/Vhen the valve 11 is open, the forces acting upon the stem to close the valve are boilerpressure in chamber 19 multiplied by the area of the diaphragm 14 and a constant. Tending to hold the valve in this position is the pressure in chamber 7 multiplied by the area of diaphragm 13 and a constant. As the throttle-valve 9 closes and reduces the pressure in the chamber 7 a certain point will be reached at which the boilerpressure on the diaphragm 14, which has not been reduced, overcomes the pressure in chamber 7, despite the larger diaphragm area upon which the latter operates and closes the valve. From this it follows that the valves 11 act to close a certain portion of the nozzle area when throttling has reduced the pressure in the chamber 7 to a predetermined point, this point bein@r such as to indicate that portions of the nozzle area can safely be shut off. Immediately upon the shutting off' of a nozzle by a valve 11, if the throttlevalve 9 be assumed to remain in a constant position, the pressure in chamber 7 will rise, due to the decreased outflow area. This rise will not, however, cause the valve to open, since a new force tending to hold the valve closed has been created by reason ofA l illustration it maybe assumed that this takesr place when the throttled pressure reaches ninety per cent. of the boiler-pressure. The second valve mav be arranged to open at ninety-three per cent. and the third valve at ninety-six per cent. of the boiler-pressure. Where a greater number of valves is employed, the pressure differences between the points of operation may be smaller.

lln designing the diaphragms, valves, &c., care must be taken that the drop in pressure in chamber 7 due to the opening of a valve is not suicient to cause the valve to immediately close again.

In Fig. 3 is shown a compression-spring 22 located within the cap 18 and pressing on the valve-stem. The stress on this spring can be adjusted by the movement of the screw 23, extending through the ca 18 and coperating with the nut 24 to a just the percentage of boiler-pressure at which the valve will open. The effect of the sprin is su plemental to the boiler-pressure an shoulid be of relatively small amount.

In accordance with the provisions of the patent statutes l have described the principle of `operation of my invention, together with the apparatus which l now consider to represent the best embodiment thereof; but l desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other means.

What l claim as new, and desire to secure by Letters Patent of the United States, is

1. ln a governing mechanism for an elastic-fluid motor, the combination of a primary means for determining the supply of motive fluid to the motor, with a subdivided secondary means for automatically apportioning the motive fluid to the huid-discharging devices in accordance with the load.

2. ln a governing mechanism for an elastic-fluid motor, the combination of a plurality of nozzles or Huid-discharging devices, primary means for determining the amount of motive fluid supplied to the motor, and a plurality of secondary or distributing means which receive the fluid after it has been acted upon by the primary means and distribute it to the minimum number of nozzles or devices which will satisfy the demand for energy.

3. An elastic-fluid motor, in combination IOO with a plurality of independent and successively-acting valves for regulating the-ad mission of motive l'luid to the turbine, which respond automatically to changes in 'l'luidpressure, and a valve which operates between the opening and closing of the regulating-valves to take care of intermediate load values.

4. An elastic-fluid motor, in combination with a plurality of separately-actuated valves for regulating the admission of motive vfluid to the turbine, which respond to changes in {luid-pressure, and a valve responding to speed changes of the motor, which varies the Huid-pressure and causes the valves to operate in predetermined order and also regulates the Vfluid passing to the motor.

ln a governing mechanism for elasticl'luid turbines, the combination of a pluralityT of regulating-valves which open and close one after the other in response to changes in fluid-pressure, and a valve acting between the opening and closing of each of said pressure-actuated valves, which assists in varying the volume of fluid passing to the motor and at the same time determines the opening and closing of the regulating-valve.

6. In a governing mechanism Vfor elasticfluid motors, the combination of a movable element, valves responding to pressure variations for regulating the admission of fluid to the rotating element, and a valve also acting on the iluid passing to the element and responding to speed variations thereo'l for controlling the admission-valves.

7. In a governing mechanism for elasticlluid motors, the combination of a movable element, a plurality ol successively-acting valves for regulating the admission of 'lluid to the rotating element, and a valve which assists in regulating the admission of luid to the rotating element and also controls the action ol' the successively-operating admissionvalves.

8. ln a governing mechanism for elasticfluid motors, the combination of a movable element, successively-acting valves regulating the admission of Vl'luid thereto, the valves being acted upon by the pressure of the source of supply and also by that entering the rotating element, and a throttle-valve which regulates the admission of Vfluid to the rotating element and also controls the successive action of the admission-valves.

9. A turbine comprising relatively movable elements, in combination with an admission-valve for admitting motive fluid to the turbine, the said valve being urged toward its seat by the pressure of the 'fluid admitted to the turbine, and a throttle-valve located between the source of supply and the turbine which, in addition to regulating the pressure of the source of supply, controls the movements of the admission-valve.

10. A turbine comprising relatively mov@ able elements, in combination with a plurality of successively-acting admission-valves which are subjected to the boiler-pressure and also to the inlet-pressure, and a valve responding to speed changes of the turbine for regulating the inlet-pressure and also the opening and closing of the valves.

11. A turbine comprising relatively rotating parts, in combination with a plurality of independent and successively-actuated valves which respond to changes in fluidpressure, and a valve acting on the main Huid-supply which regulates the admission of 'fluid to the turbine between the opening and closing of each two of said valves.

12. A turbine comprising relatively rotating parts, in combination with a plurality of independent and successively-actuated valves which are subject to boiler and inlet pressures, and a valve acting on the main fluid-supply which regulates the admission of' fluid to the turbine between the opening and closing of each two of said valves and also controls the successive actuation of the valves.

13. In combination, a turbine, a passage for conveying motive fluid thereto, a throttle-valve located 'in said passage for controlling the admission of Vlluid to the turbine, individual and successively-acting valves which are located beyond the throttle-valve and also control the admission of luid to the turbine, and motors for operating the valves which depend for their action upon the difference between the supply and inlet pressures as created by the throttle-valve.

14. In a governing mechanism for elasticlluid turbines, the combination of a plurality ol independent and successively-acting valves Jfor regulating the admission of fluid to the turbine, a separate motor for operating each of the valves, conduits for subjecting the motors to the pressure of the source of supply, conduits for subjecting the motors to an opposing inlet-pressure, and a throttle-valve which varies the inlet-pressure as the demand for l'luid changes.

15. In a governing mechanism, the combination o'l' an admission-valve, high and low pressure diaphragms for closing and opening the valve, a conduit for conveying Alluid to the high-pressure diaphragm, another conduit ior conveying Vlluid to the lowpressure diaphragm, and a valve for varying the pressure of the l'luid acting on the low-pressure diaphragm.

16. ln a governing mechanism, the combination of a plurality of successively-acting admission-valves, high and low pressure diaphragms for closing and opening the valves one after the other, conduits for conveying 'lluid to the high and low pressure diaphragms, and a valve responding to speed IOO IIO

changes, Which varies the pressure to which the diaphragms are subjected.

17. In a governing mechanism, the combination of a plurality of successively-acting admission-valves which open and close in response to pressure variations, and a throttlc-valve the action of Which precedes the opening or closing of each of the admissionvalves.

18. In combination, a turbine, devices for discharging Huid against the moving buckets, admission-valves sensitive to pressure variations for regulating the admission of fluid to the devices, Which are less in number than said devices, and a throttle-valve which regulates the passage of iuid to the unvalved device and also controls the action of the admission-valves.

19. An elastic-uid motor, in combination With a plural-ity of separately-actuated valves for regulating the admission of m0- tive iiuid to the turbine, and a valve Which controls the operation of the separately-actuated valves and in addition thereto regulates the supply of fluid to the motor.

In Witness whereof I have hereunto set my hand this 28th day of March, 1905.

JOHN G. CALLAN.

Witnesses:

JOHN A. McMANUs, Jr., HENRY O. WESTENDARP.

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