US861085A - Governing mechanism for turbines. - Google Patents

Description

No. 861,085. PATENTED JULY 28, 1907.

- J. G. GALLAN:

GOVERNING MECHANISM FOR TURBINES.

APPLICATION FILED JAIL 2. 1906.

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No. 861,085. PATENTED JULY 23, 1907. J. GALLAN: GOVERNING MECHANISM FOR TURBINES.

APPLICATION FILED JAN. 2. 1906.

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JOHN G. CALLAN, OF LYNN,

MASSACHUSETTS, ASSIGNOR TO GENERAL ELECTRIC- COMPANY,

A CORPORATION OF NEW YORK.

GOVERNING MECHANISM FOR TURBINES.

Specification of Letters Patent.

PatentedJ 1113 23, 1907.

Application filed January 2,1906. Serial No- 294,162.

To all whom it may concern:

Be it known that I, JOHN G. OALLAN, a citizen of the United States, residing at Lynn, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Governing Mechanism for Elastic- Fluid Turbines, of which the following is a specification.

The present invention relates to mechanisms for governing the passage of motive fluid from one stage to another in a multi-stage turbine, and has for its object to improve their construction.

In the accompanying drawings, which are illustrative of one embodiment of the invention, Figure 1 is a partial section of a multi-stage turbine, the section be-- ing taken on line l1 of Fig. 2; Fig. 2 is a partial plan and sectional view of the same, the section being taken on line 22 of Fig. 1; Fig. 3 is a detail view of a baffler to prevent the stage-valves from opening too rapidly;

Fig. 4 is a detail view of an admission-valve and its actuating cross-head; Fig. 5 is a diagrammatic view of a speed-responsive device as applied to a turbine fitted with my improved valve mechanism, and Fig. 6 is a view showing a cross-head for operating the stage valve. 1 represents the casing of the turbine which is divided by diaphragms 2 into two or more stages. Instead of the arrangement shown, each stage may be contained in a separate casing, and the casings connected or arranged in any desired manner.

Mounted on the casing is a head 3 having one or more openings to receive the lower end of the valve chest 4 and the nozzles 5, or other fluid discharging devices,

which may be expanding or non-expanding in character. In each stage is mounted a wheel 6 having one or more rows of wheel buckets 7. When two or more rows of buckets are provided for each stage, a row more or less complete of stationary intermediate buckets 8 is arranged between each two rows of wheel buckets. The casing is connected to atmospheric or condenser exhaust in the usual manner.

The casing is provided with an internal shoulder 9 that supports the upper diaphragm, and in this shoulder are cored passages 10 and 11, the former leading from the first stage and the latter communicating with the second stage-nozzles 12, of which there may be one, two or more. It is to be understood that there are or may be other stage-nozzles which are normally open and are not controlled by automatic stage-valves. The passages 10 and 11 terminate in a valve casing 13 which is preferably but not necessarily bolted to the periphcry of the wheel casing. The valve casing is provided with a partition 14 supporting a valve seat 15. The

space above the valve 16 and the partition is connected to the first stage by the passage 10, while that below is connected to the second stage-nozzles by the passage 11. The lower end of the valve stem 17 is provided with a piston 18 of less diameter than the valve and located in the cylinder 19, the latter being removable and held in place by the detachable head 20.

It is 'to be observed that although the piston 18 is smaller in diameter than the valve, it is subjected, under the control of the governor, to a superior pressure by reason of the fact that live steam is admitted to the cylinder 19 whereas the pressure above the valve is that due to the steam after it has passed through the first stage-nozzles or other devices and wheel. The clearance between the lower surface of the piston 18 and the cylinder head should be small so as to prevent too rapid opening of the stage-valve when elastic fluid is used as the motive power medium.

It may be here stated that some other fluid, such as water, oil or air, may be used to actuate the stage-valve or valves. The upper end of the cylinder is provided with an inturned flange 21 that acts as a stop to limit the upward movement of the piston and valve. The upper end of the valve stem is provided with a piston 22 freely moving in a cylinder 23 formed on the upper head 24 and acts as a dash-pot. Steam or other fluid, elastic or non-elastic, is admitted by the pipe 25 to the under side of the lower piston 18 when it is desired to raise the valve, and is exhausted therefrom when it is desired to close the valve as will be described later.

Steam or other elastic fluid is admitted to the valve chest 4 by a suitable conduit, Fig. 5, and the passage of fluid from the chest to the nozzles or other fluid discharging devices 5 is controlled by a plurality of separately actuated valves 26. "he-admission-valves are successively actuated both in opening and in closing, and have an open position and a closed position but no intermediate. The mechanism for actuating the admission-valves is the same as that employed to actuate the pilot or relay-valves so the description will be chiefly directed thereto.

Situated above the valve chest 4 is a frame 27, and mounted therein are as many cross-heads 28 as there are admission-valves to be controlled. In this case certain of the cross heads will actuate the pilot valves and also the nozzle valves. Instead of this arrangement, the pilot valves may have separate cross-heads of the character shown and actuated in the same manner. If desired, however, one cross-head may control two or more stage-valves, as for example Where the succeeding stages of lower pressure after the second are valved, or where it is desired ,to simultaneously open two or more stage-valves in the same stage. Where the cross-heads are employed to actuate admission-valves they are directly connected to their stems 29, Fig. 4,

' pressure and not the initial pressure.

haust.

and where employed to control stage-valves, to the stems 30 of the pilot-valves.

In Fig. 6 is shown a separate cross-head for actuating a pilot valve. Between the stem and the cross-head is interposed a coiled compression spring 31 contained in a head 32. At the upper end of the frame 27 are as many cylinders 33 as there are pilot-valves 34, the latter being of suitable form, as for example of the piston type. To the cylinder, and at a point below the pilotvalve, is connected a pipe 35 leading to a source of supply. It may be connected to a separate source of sup ply, to the valvechest direct, as by a pipe 36, or to one of the passages 37 leading to one, two or more nozzle sections. The latter arrangement is the one shown, and it is to be understood that the parts are so related that the nozzle valve 26 is opened before the cross-head moves the pilot-valve to a position to admit steam to the cylinder 19. To state the matter in other words, the stage-valves are directly under the control of the governor and operate between the opening and closing of the admission-valves, not simultaneously therewith. By taking steam for operating a stage-valve from the pipe 36, an admission and a stage-valve may open or close simultaneously, but the opening or closingof a stage-valve is not in any sense under the control of an admission-valve, but is under the control of the speedgovernor.

One advantage of the construction shown resides in the fact that upon such a decrease in load as will close the nozzle or admission-valve 26 the pressure in the pipe 35 and the conduits connected therewith will be materially reduced because it then becomes the stage To the central portion of the casing of the pilot-valve is connected the pipe 25 leading to the cylinder of the motor for actuating the stage-valve. The upper end of the cylinder is connected by thepipe 38 to atmospheric or other eX- Ipreier to connect the pipe to a condenser in order to obtain the benefit of the latter when it is desiredito lower the piston 18 and close the stage-valve.

Mounted on the frame 27 are as many actuators 39 as there are cross-heads. These actuators are carried in a suitable frame supported by the spindle 40, and

' are kept constantly moving to and fro by the lever 41 through suitable means driven by the turbine shaft or by separate means. Pivotally mounted on each of the I actuators are dogs 42 and 43 which at all times tend to engage with the shoulders 44 and 45 on the cross-head by reason of the spring 46. The action of each pair of dogs is controlled by a shield plate 47, the latter being loosely mounted on the spindle 40 and connected to the speed governor by a rod 48 so that as the speed of the turbine varies the number of valves in service will be changed to suit the requirements. The shieldplates for the several cross-heads are connected together and set angularly one behind the other by a slight amount so as to cause successive operation of the admission and stage-valves. By suitably proportioning the width of the active face of each shield-plate to the dogs, each valve may, with the shield in a central position, be opened and closed once for each complete movement of an actuator 39. This arrangement has the advantage of reducing the number of admissionvalves required. The regulating-valve will then open and close with a definite periodicity and the period will be unvarying.

In Fig. 2 is shown two stage-valves arranged for successive operation, but I may use only one valve or a number greater than two and operate them successively. The valves may beused in one stage only or in'two or more stages as best suit the requirements. I have described the admission-valves as being mechanically operated and the stage-valves as being operated by fluid under pressure, but it is to be understood that I may under certain conditions operate admissionvalves in a manner similar to the stage-valves if desired.

The operation of the mechanism on increasing load, assuming that some of the admission-valves are open and the pressure above the stage-valve greater than that below it, is as follows Assuming a change in load, the speed governor adjusts a shield-plate 47 so that the next upward stroke of the actuator 39 causes the upper dog to engage the shoulder 44 and raise the cross-head 28 and pilot-valve 34. "This will permit steam to flow from the passage 37 (it being understood-that the admission-valve 26 has been previously opened), or from pipe 36 to pipe 35, cylinder 33, thence to pipe 25 and cylinder 19. The fluid thus admitted to the cylinder overcomes the pressure on the upper side of the stagevalve 16 and the latter rises and permits steam to pass freely from passage 10 to passage 11, thence to the sec- 0nd stage nozzles 12, or to the nozzles of any other stage if desired. It is to be noted that when the stagevalve 16 is open, the pressure in the passage 11 is higher than when the valve is closed because in the former case it is equal to that in the first stage and in the latter case to the pressure in the second stage, be-

cause of the nozzles 12 open thereto. This action increases the torque of the turbine, due to the admission of more steam to the first stage and also to the second and succeeding stages. The dash-pot piston 22 is loosely fitted into its cylinder so that when in the position shown in Fig. 1, the pressures above and below it are the same or substantially so. On a decrease in load accompanied by an increase in speed the governor moves a shield-plate 47 to'a position where it permits the lower dog to engage the shoulder 45 on its next downward stroke and lower the crosshead and pilot valve. This cuts off steam from the pipe 25 and opens it and the cylinder 19 to the condenser exhaust which quickly causes the piston 18 to drop and close the stage valve owing to the stage pressure in passage 11 which unbalances the pressures on the piston. A greater increase in load will open the remaining admission and stage-valves one after the other and a greater decrease in load will close the admission and stagevalves one after the other. I

In Fig. 3 is shown a batfler for preventing the stagevalves from opening too rapidly by retarding the flow of fluid, and preferably is located as near the cylinder 19 as possible. It comprises ashell 50 having a bore of two different diameters, one forming a chamber 51, the other closely fitting the screw-threaded removable plug 52.- Located in the chamber and surrounding the plug is a strainer 53 made of gauze and a cylinder 54 made of perforated metal. Steam or other fluid, elastic or non elastic is admitted to the shell by the passage 55, and leaves it by the spiral passage formed in the plug. In

some cases it will be necessary to use both the dash-pot and baffier and in other cases only one of them. Instead of using the specific form of leather shown, I may use other forms.

In Fig. 4 is shown a nozzle-valve 26 connected by its stem 29 with a cross-head 28 the latter being moved to and fro by dogs similar in construction and operation to those previously described. I

In Fig. is shown a speed-responsive device 57 that is connected to the rod 48 which moves the shield plates by the lever 58. The lever 41 that moves the actuators 39 back and forth is driven by a crank 59 which in turn is driven by the main shaft of the turbine through suitable speed-reducing gearing.

It will be seen that the admission-valves are mechanically and positively opened and closed, while the stage-valves are opened and closed by fluid-actuated motors in response to speed changes, the same speed governor being employed to control both sets of valves.

This arrangement is simpler, costs lessand requires fewer parts than where both admission and stage-valves are mechanically operated. It is also less difiicult to install and take down, and the stage-valves can be located at whatever point or points on the turbine are most convenient. If anything happens to a stage-valve it can be disconnected and the remainder of the apparatus will operate as before.

While I have shown the pilot-valves operated and controlled by crossheads, actuators, dogs, shieldplates, etc., my invention is not to be considered as being limited thereto except as specifically referred to in the claims.

It is evident that my invention can be used in connection with any form of admission valve or valves, and this whether the valve or valves is or are arranged to open and close with or without throttling.

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

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

1. In a governing mechanism for multi-stage turbines, the combination of an admission valve, means tor actuating the admission valve, a stage-valve, means for actuating the stagevalve, and a speed-responsive device which acts on the stage valve to open it subsequent to acting on the admission valve and prior to acting on said admission valve to close it.

2. In a governing mechanism for mnlti-stage turbines,

the combination of a plurality of admission-valves, means under the control of a speed governor for actuating the admission valves, a plurality of stage valves, means under the control of the speed governor for actuating the stagevalves, and a speed governor which acts on the stagevalves successively and between the periods when it acts on the admission-valves.

3. In a governing mechanism for multi-stage turbines, the combination of a device moved by a speed governor, an admission valve under the control of said device, a stage valve, a fluidactuated motor for controlling the stagevalve, the diameter of the valve being greater than that of the motor piston, and a pilot-valve for controlling the stage-valve that is connected to the device operated by the speed governor.

4. In a governing mechanism for multi-stage turbines, the combination of admission and stage-valves, a mechanical means for opening and closing the admission-valves, a fluid-pressure means for actuating the stage-valve or valves, and a speed-responsive device that is common to and controls the operation of the valves.

5. In a governing mechanism for multi-stage turbines, the combination'of admission and stage-valves, a mechanical means for opening and closing the admission-valves, a fluid-pressure means for actuating the stage valve or valves, one or more pilot valves for controlling the action of the stage-valve-or valves, and a speed-responsive device that is common to said mechanical means and the pilotvalve or valves.

6. In a governing mechanism for multi-stage turbines, the combination of admission-valves, cross-heads connected to the valve stems, actuators for moving the cross-heads to and fro, one or more stage-valves, fluid-pressure motors for actuating them, one or more cross-heads for the stage.

valves, one or more actuators for moving the last-mentioned cross-heads to and fro, one or more pilot valves for the motors actuated by the cross-head or heads, and a speed-responsive device which controls the action of the admission-valve actuators and the pilot-valves.

7. In a governing mechanism for multi-stage turbines, the combination of a plurality of separately actuated admission valves, one or more stage-valves, one or more fluid-pressure motors for actuating the stage-valves, a baffiing device in the conduit between the source of supply and a motor, and a speed-responsive device for controlling the admission of motive fluid to the turbine. l

8. In a governing mechanism for multi-stage turbines, the combination of a plurality of separately actuated admission-valves, one or more stage valves, one or more fluidpressure motors for actuating the stage-valves, one or more dash-pots for damping.the action of the stage-valve or valves, and a speed-responsive device for directly controlling the action of the admission and stage valves.

9. In a governing mechanism for multi-stage turbines, the combination of a speed-governor, a stage valve, a fluid actuated motor for opening and closing the stage valve, a conduit for admitting high pressure fluid to the motor, and a pilot valve moved by the governor for regulating the passage of fluid through the conduit to the motor.

In witness whereof, I have hereunto set my hand this twenty-ninth day of December, 1905.

' JOHN G. CALLAN.

Witnesses ALEX. F. MACDONALD, JOHN A. MCMANUS, Jr.

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