US991950A - Valve-control system. - Google Patents

Description

M.- B. CARROLL. VALVE UONTRDL SYSTEM. ArPLIoATxoN FILED snm-1a. 1910.

Patented May 9,. 1911.

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-UITE STATES T OFFICE.

MORRIS B. CARROLL, 0F SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CGRPORATION OF NEW YORK.

VALVE-CONTROL SYSTEM.

Specification of Letters Patent.

Patented May 9, 1911.

Application led September 13, 1910. Serial No. 581,827.

To all tuhom it mag/concern:

Be it known that I, Mounts B. CARROLL, a

.citizen of the United lStates, residing at "Schenectady, county of Schenectady, State yfrom a hi h ressure-reci ro'catinfr env-ine ZD D or turbine. Inasmuch as the supply 'of low pressure steam may fail at times, or be insutlicient to carry the load imposed on the turbines, it has become customary to provide a main supplying high pressure steam, and a set of valves for admitting said high pressure steam to the turbine in case of necessity. These valves are placed under t-he control of 'the speed governor of the turbine, and are so arrai'iged andI connected that they do not open until the speed governor has fully opened the low pressure valve or valves. But when a turbine equipped with this type of governor is used to drive an electric generator connected in multiple with other units independently driven, the turbine tends to lose its load when changing from low pressure operation to high pressure operation, or if adjustedto carry a certain load under high pressure steam, it- Will tend to carry double this load or more when changing bac-k to 10W pressure operation.

To obviate this shifting of load, I provide the valve chest'of the hydraulic motor, which actuates the turbine valves, with a movable port-carrying, element, preferably a sleeve surrounding thepilot valve and containing the portsthrough which the motive fluid passes to the cylinder of the motor. This sleeve is arranged to be moved longitudinallyl in response to variations in the pressure ofthe low pressure steam, so that it will automatically Shift the pasition of the ports an amount proportional to the travel of the governor rod 'when changing 'over from low pressure to high pressure operation and vice versa for the purpose of' getting the same speed regulation of the turbine when operating on either low pressure or high pressure steam.

In the accompanying drawing, Figure 1 is an end elevation of a mixed pressure turbine of the hydraulic motor 6.

equipped with my invention, and Fig. 2 is a section of the hydraulic valve motor showing my improvement.

The turbine is driven normally by low pressure steam supplied through a conduit 1 in which is a butterfly valve operated by a rack 2 and rod 3, which is actuated by the cam shaft L connected to the piston rod 5 The lever 7 of the speed.A governor 8 is connected by the rod 9 to one end of said floating lever 10. The other end of said floating lever is con ected b a link 1l with the arm 12 ivoted a? one enclto thel frame 13 of the hy raulic motor and at the other end to the piston rod 5. At an intermediate point on the lever 10 is ivoted the stem 14|.v of the pilot valve 15. A l these devices are Well known and form no part of my invention. The additions which I have made comprise a sleeve 16 or its equivalent interposed between said valve and its casing 17, said sleeve containing an inlet port 18 registering with the inlet 19 for the motive fluid, and two outlet ports 20 registering with the/admission ports 2l of the motor cylinder, which are controlled by the pilot valve. The ports 18 and 21 are elongated so that the sleeve can be moved .longitudinally for some little distance Without interrupting the How of the motive fluid.

Situated below the valve casing 17, and in line with the pilot valve, is a small cylinder 22, containing a piston 23 Whose rod 24 is attached to one end of the sleevel. The Weight of the piston and sleeve is counterbalanced, preferably by a Weight 25 ora lever 2G pivoted to the end of the rod 24 which is extended through a stutiing box 27 on the bot-tom' of the cylinder 22. is adjustable to vary the pressures at which the sleeve 16 will be operated. The space above the piston is open to the atmosphere through the short pipe 28, but the space under the piston is connected by a pipe 29 With the low pressure conduit 1.

The operation is as follows: When the load on the turbine is-increased, the speed falls and the governor lifts its lever 7 and the rod The weight 25 9. The pilot valve 15 is moved up, admit- .the conduit 1 is openc'd sufficiently to supply the steam required to carry the increased load., The follow-up devices 10= 11, 12

cient high pressure valves to bring the speed return the pilot valve to its normal mid-position, in which it shuts oli' the motive fluid. This action may continue until the lovv pressure valve is ivide open. The vacuum on the turbine due to the condenser tends to Work back to the conduit l, and is liable to cause trouble owing to the leakage of air into said conduit. But at this point in the operation, the vacuum is set up also in the lower part of the cylinder 22, so that the atmospheric pressure forces down the piston 26 and pulls down the sleeve 1G against the shoulder 30. This has the saine effect as the lifting of the rod 9 oy the speed governor, that is 'to say, the upper port 20 is opened and motive fluid is adin-itted to the upper part ofthe cylinder 6. The resulting further downward movement of the piston rod 5 opens all or most of the high pressure valves and admits high pressure steam to the turbine. This tends to increase the speed of the machine, but the s eed governor automatically takesc'are ot this, closing suliof the machine to the same rate as when operating on low pressure steam at. the same load.

Vhen the supply of low pressure steam picks up, the pressure thereof on the under side-of the piston 23 will-shovethe` sleeve up again to the position shown in Figi 2, so that the' governor Will `again control the machine through the low pressure-valve.'

It Will be seen that this device provides for positively bringing intooperation the desired set of valves at the time when the load is changing from `low,y to high pressure steam or vice versal by causing the piston of the hydraulic motor to occupy a higher position in its cylinder, for a given position of the speed governor, when the turbine is operating on low pressure steam than said piston occupies when the machine is operating on high pressure. f

It wvill of course be remembered that the low pressure valve is .controlled by the motor piston during the movement of said piston in the upper part of the cylinder, and that the high pressure valves are operated when the piston is moving in. the lower partI of said cylinder.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is z- 1. The combination with the hydraulic valve motor of a mixed pressure turbine, ot means for shifting longitudinally the position of the admission ports of said motor yvith reference to the mid-position 'of the pilot valve of said motor.

2. The combination with the hydraulic valve motor ofa mixed pressure turbine, of a longitudinally movable sleeve surrounding the pilot valve of said mot-or and provided with suitable'ports, and means responsive to pressure in the low pressure conduit of said turbine for operating said sleeve.

3. The combination with t-lie hydraulic valve motor of a mixed pressiire turbine, lont' a longitudinally movable sleeve surrounding the pilot valve of said motor and provided with an elongated inlet port and two outlet ports, a valve easing having an inlet port Vand two elongated admission ports respectively registering With the ports in said sleeve, and means controlled by the pressure in the low pressure conduit of said turbine for shifting said sleeve longitudinally.

4. The combination with the hydraulievalve motor of a mixed pressure turbine, of means for shifting longitudinally the pasition of the admission ports of said motor with reference to the ymid-position o't the lpilot valve of said motor, said means comprising a piston exposed on one' side lo atmospheric pressure and on the other side to the conduit pressure.

In witness whereof, I lia-ve hereunto set my hand this 12th day of September, lfl'lO.

MORRS B. CARROLL.

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