US3692419A - Elastic fluid turbine system - Google Patents

Elastic fluid turbine system Download PDF

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Publication number
US3692419A
US3692419A US149640A US3692419DA US3692419A US 3692419 A US3692419 A US 3692419A US 149640 A US149640 A US 149640A US 3692419D A US3692419D A US 3692419DA US 3692419 A US3692419 A US 3692419A
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Prior art keywords
turbine
valve
control valve
speed
braking control
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Expired - Lifetime
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US149640A
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English (en)
Inventor
Shigenobu Katagiri
Mitsuhisa Yokota
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Toshiba Corp
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Tokyo Shibaura Electric Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/16—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type
    • F01K7/22—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type the turbines having inter-stage steam heating
    • F01K7/24—Control or safety means specially adapted therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/006—Arrangements of brakes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/02—Shutting-down responsive to overspeed

Definitions

  • the steam admission control valve is actuated to open June 4, 1970 Japan ..45/47608 if the turbine Speed rises above a predetermined value or at a rate of change above a predetermined value, lll "4154533); whereby an undesirable turbine overspeed is 58 Field of Search ..415/13, 17, 30 prevented 9 Claims, 4 Drawing figures PATENTEDSEP 19 m2 3.692.419
  • This invention relates generally to an elastic fluid turbine system and more particularly to a turbine system of the type adapted to be operated by a motive fluid having relatively low energy density.
  • a main control valve which controls the admission of steam to a high pressure turbine, is generally closed entirely at substantially 105 percent of the rated speed
  • an intercept valve which controls steam flow from the high pressure turbine to a low pressure tubine, is closed entirely at substantially 102.5 percent of the rated speed.
  • Another object of this invention is to provide a braking means which operates quickly and reliably to prevent an unfavorable overspeed of the turbine system.
  • Still another object of the present invention is to provide a novel and improved control means for actuating the braking means at a predetermined overspeed.
  • a still further object of the invention is to provide a control means for actuating a braking means if the turbine speed accelerates at a higher rate than a preselected value.
  • a reverse torque generating turbine for braking against a rotational output of the high and low turbines.
  • a braking control valve for controlling admission of the motive fluid to the reverse turbine and a control means for the braking control valve. If the turbine speed rises above a predetermined level or accelerates at a rate above a predetermined level under the control of the high and low pressure turbines, the braking control valve automatically actuates to open so that the reverse turbine generates a braking force to prevent an undesirable overspeed condition from arising.
  • FIG. I shows a schematic diagram of one embodiment of an improved turbine system in accordance with the present invention.
  • FIG. 2 is a schematic diagram of another embodiment of a turbine system according to the present invention.
  • FIG. 3 is a schematic diagram of one embodiment of a control means for the system according to this invention.
  • FIG. 4 illustrates a schematic diagram of another embodiment of a control means for the system according to the present invention.
  • a steam generated by a boiler 1 flows through a control valve 2 to a high pressure turbine 3 and expands therein, and then flows to a moisture separator 4 of conventional design wherein a certain portion of the moisture entrained in the steam is removed.
  • the stem then flows through an intercept valve 8 and a cross-over line 9 to a low pressure turbine stage 5 including low pressure tur bines 6 and 7, and then to a condenser 10.
  • the high and low pressure turbines 3 and 6 and 7, respectively, have a common load such as an A.C. generator I I.
  • a reverse torque generating turbine 12 coupled to a common shaft of the high and low pressure turbines 3, 6, and 7, hereinafter referred to as the main turbine unit, for braking the rotational output thereof.
  • Maximum output of the reverse turbine 12 may be established at about 10 percent of the output of the main turbine unit.
  • the motive fluid for the reverse turbine 12 is supplied from the boiler 1 under the control of a braking control valve 13 provided adjacent the motive fluid inlet of the reverse turbine 12.
  • the braking control valve 13 In normal operation, the braking control valve 13 is fully closed, but should the turbine speed rise to an undesirable overspeed condition, the braking control valve 13 will be opened by a control means which hereinafter will be described in connection with FIGS. 3 and 4. Hence, the reverse turbine generates a torque in the reverse rotational direction relative to the torque being generated by the main turbine unit to restrict the speed increase thereof resulting essentially from the revaporized steam in the lower stage turbines.
  • FIG. 2 illustrates another embodiment of the system constructed according to the present invention
  • a reverse torque generating turbine 12 similar to that shown in FIG. 1 is provided, but in this case the motive fluid for driving the reverse turbine 12 is supplied from the main steam line being taken from a point downstream from the intercept valve 8, such as the cross-over passage 9, through a braking control valve 13.
  • the braking control valve 13 is actuated to an open position by the control means, as will hereinafter be explained, the revaporized steam in the low pressure turbine stage flows to the reverse turbine 12 as well as to the low pressure turbines 6 and 7.
  • the torque in the reverse rotational direction generated by the reverse turbine 12 accordingly is operative to restrict the speed rise of the system.
  • braking control valve 13 it is preferable to position the braking control valve 13 as near the reverse turbine 12 as possible in order to decrease the time lag and to generate a braking force in quick response to the actuation of valve 13, wherein the same is opened.
  • FIG. 3 there is illustrated an embodiment of a servomechanism for controlling the braking control valve 13.
  • a governor which is independent of the main governor for controlling the main control valve 2 and the intercept valve 8 and is designed such that after the control and intercept valves have been entirely closed, the valve 13 begins to open at a turbine rotational speed of about 106 percent, for example, of the rated speed and reaches its full opening at about 108.5 percent, for example, of the rated speed. Accordingly, after the control and intercept valves have been closed at a turbine speed above approximately 105 percent of the rated speed, if the turbine speed continues to rise substantially, the braking control valve 13 begins to open so that the steam flows into the reverse turbine 12 to generate the necessary braking force.
  • the reference numeral 14 indicates a worm coupled to the turbine shaft and operatively engaged with worm wheel 15 mounted on a shaft of a conventional main speed governor 16 which operates the control and intercept valves in a conventional manner.
  • the governor 16 moves its operating rod 17 up and down, respectively, in response to lower and higher speeds of rotation of the wheel 15.
  • the operating rod 17 is coupled to a piston rod having thereon two lands of a pilot valve 18.
  • This valve 18 has a sleeve or a cylinder 19 including a top port for drain, a bottom inlet port for receiving a hydraulic fluid, and an intermediate port 20.
  • the intermediate port 20 is connected to a lower chamber of a servomotor 21 having a stationary cylinder in which a piston 22 is slidably disposed, being forced toward one end of the cylinder, or downward, as illustrated, by a compressed spring 23.
  • Upper and lower rods 24 and 25 are secured to the piston 22, the lower rod 25 being operatively connected to the control and intercept valves 2 and 8, shown in FIG. 1, through a suitable servomechanism, not shown, whereby the servomotor 21 functions as a speed relay.
  • a speed/load changer, or load setting device, 26 is provided for controlling the position of the right end of a lever 27, which is linked at its left end to the upper rod 24 of the servomotor 21 and at an intermediate point to the cylinder 19 of the pilot valve 18 through a connecting rod.
  • Meshing with the worm 14 is a worm wheel 28 to operate a secondary speed governor 29 having an operating rod 30 which moves up and down, respectively, in response to lower and higher speeds.
  • This operating rod 30 is connected to the piston rod of a pilot valve 31.
  • the pilot valve 31 has an upper inlet port for receiving a hydraulic fluid and a lower port 32 which is connected to the lower chamber of a servomotor 33 having a stationary cylinder and a piston 34 with a rod 35.
  • the piston 34 is biased downwardly by a biasing spring 36.
  • the movement of the rod 35 is fed back to the sleeve of the pilot valve 31 through a restoring linkage including a lever 37 with a fulcrum at an intermediate point thereof, a link 38 and a lever 39.
  • the left end of the lever 39 is positioned by a setting device 40 to determine the speed at which the braking control valve begins to open.
  • Movement of the rod 35 is also transmitted to a lever 41 mounted fixedly on one end of a torque imparting shaft 42 which is rotatably supported by a suitable means.
  • the braking control valve 13 and a servo device for actuating the same are disposed substantially apart from the servomotor 33. ln order to transmit the movement of the servomotor rod 35 to the braking control valve servo device, the torque imparting shaft 42 is employed. Therefore, other transmission means, such as a hydraulic system, may be used.
  • Mounted fixedly on the other end of the shaft 42 is a lever 43 which links operatively to a piston rod 44 of a pilot valve 45 through a link 46 and a lever 47.
  • the pilot valve 45 has a stationary sleeve having an upper port for drain, a lower inlet port 48 for receiving a hydraulic fluid and an intermediate port 49 which is connected to the bottom chamber of a servomotor S0 for operating the braking control valve 13.
  • the servomotor 50 has a stationary cylinder and a piston 51 which is biased downward by a compressed spring 52.
  • a rod 53 on the piston 51 is connected to the stem of the valve 13.
  • There is also provided a restoring linkage including a lever 54 having a fulcrum at an intermediate point thereof, a link 55, and the lever 47 in order to feed back the movement of the servomotor rod 53 to the piston rod 44 of the pilot valve 45.
  • an accumulator 56 supplied with the hydraulic fluid through a line 57 having an orifice 58 therein and also supplying the inlet port 48 of the pilot valve 45 with the fluid through a line 59.
  • the rod 25 of the speed relay 21 moves up and down in response to speeds which are respectively lower and higher than the rated speed to actuate the control and intercept valves 2 and 8, during which time the brake valve 13 is in a completely closed condition.
  • the lower chamber of the servomotor 50 then receives hydraulic fluid from the accumulator 56 through line 59, inlet port 48 of pilot valve 45 and port 49, whereby the braking control valve 13 begins to open as the piston 51 and rod 53 thereof are moved upwardly. In this manner the braking control valve 13 may be actuated to open and close in accordance with the turbine speed under the control of the governor 29.
  • the brake control valve 13 preferably is adapted to attain a fully open position if the turbine speed reaches 108.5 percent of its rated speed.
  • the speed at which the braking control valve 13 begins to open may be adjusted by the setting device 40 for changing the position of the left end of the lever 39.
  • the speed at which the valve 13 reaches its fully open position is determined by the design of the restoring linkage. It is preferable of course that these setting speeds be adjusted to effectively prevent an undesirably overspeed from being reached, according to the characteristics of the particular system involved.
  • the braking control valve can be controlled in a desirable manner so as to prevent the undesirable overspeed from occurring. Further, the provision of the accumulator for supplying enough hydraulic fluid to the servo device for actuating the brake control valve permits a rapid and effective generation of the braking force to be applied in response to the control means.
  • FIG. 4 shows another embodiment of the control means formed according to this invention.
  • the braking control valve 13 is operated to open when the intercept valve 8 closes with a rate of change over a prescribed value.
  • a differential element including a dashpot and a spring is provided.
  • FIG. 4 illustrates the control system being adapted for use with the turbine system shown in FIG. 2 in that the inlet of the brake valve 13 is connected in the steam line below the intercept valve 8, this embodiment also is applicable to the system shown in FIG. 1.
  • the intercept valve 8 is operated by a servomotor 60 through a lever 61 being fulcrumed at an intermediate point thereof.
  • the servomotor 60 has a stationary cylinder and a piston 62 therein which is biased downwardly by a biasing spring 63.
  • a rod 64 of the piston 62 is operatively connected to the lever 61 and has two arms 65 and 66.
  • the servomotor 60 is actuated by a pilot valve 67 having a stationary sleeve. This sleeve has an upper port for a drain line, a lower inlet port for receiving a hydraulic fluid and an intermediate port 68 connected to the top chamber of the servomotor 60.
  • a rod 69 of a spool piston of the pilot valve 67 is linked to the intermediate portion of a lever 70, the left end of which is operatively connected to a speed relay, such as the servomotor 21 shown in FIG. 3, through a suitable servomechanism.
  • the movement of the piston rod 64 of the servomotor 60 is fed back to the valve stem 69 through a restoring linkage consisting of the arm 65, a link 71 and the lever 70. Accordingly, the intercept valve 8 is actuated to open and close in accordance with the speed relay, not shown.
  • a stationary fluid dashpot 76 having a piston 77 therein.
  • An upper chamber of the dashpot 76 communicates with a lower chamber thereof through a by-pass line 78 having a needle valve 79 therein.
  • a rod of the piston 77 links to a lever 80 at its intermediate portion 80b.
  • the left end 80a of the lever 80 is operatively engaged with the link 75.
  • the intermediate port 86 communicates with a lower chamber of a servomotor 87 for actuating the braking control valve 13.
  • a piston 88 with a rod 89 connected to the valve stem of the valve 13 is forced downward by a biasing spring 90.
  • Movement of the stem 89 is fed back to the piston rod of the pilot valve 85 through an arm 91 of the stern 89, a link 92, a lever 93 with a fulcrum at an intermediate point thereof, a link 94 and the lever 84.
  • the intercept valve 8 is operated to open and close in accordance with a signal given to the left end of the lever 70.
  • the operating speed of the intercept valve 8 depends on the rate of change of the turbine speed and the movement of the intercept valve 8 is transmitted to the lever 80 of the differential element 72 through the lever 61, the rod 64, arm 66, link 73, lever 74 and link 75.
  • the change in turbine speed under normal conditions is a relatively small quantity and is relatively slow, the moving speed of the left end 80a of the lever 80 is also slow.
  • the lever 80 moves about the right end 80c, which functions as a fulcrum, because the right end is substantially supported by the springs 81 and 82, and the piston 77 of the dashpot can follow the slow movement of the lever portion 80b.
  • the pilot valve 85 keeps substantially on-port, as shown, or toward a slightly closing state, under normal operation.
  • the braking control valve 13 thereby assumes a fully closed position.
  • the intercept valve 8 is actuated to close rapidly,
  • the left end 80a of the lever 80 is thereby caused to move downward with a relatively rapid speed.
  • the lever rotates about the point 80b being pivotally supported by the stem of the piston 77 against the resilient force of the springs 81 and 12. That is, the right end 80c moves upward, so that the spool of the pilot valve 85 is raised and the hydraulic fluid flows into the bottom of the servomotor 87 to open the braking control valve 13.
  • the steam flows to the reverse turbine 12 to generate a braking force, whereby the turbine system is prevented from attaining an undesirable overspeed.
  • the differential element is provided for detecting a closing operation of the intercept valve at a relatively high rate of speed, such as may occur under a condition where it is necessary to open the braking control valve.
  • the brake valve may be actuated to an open position in rapid response to such a detection so that the braking force can be immediately and effectively used.
  • a reverse torque generating turbine stage for obtaining a braking force and a control means for controlling the same, such that the turbine system is prevented from reaching an undesirable overspeed condition at which the emergency governor will operate.
  • the system according to the present invention is especially useful in a plant where it is necessary to employ a wettable steam, namely, for example, an atomic power plant of the BWR type.
  • an elastic fluid turbine system having a high pressure turbine stage, a low pressure turbine stage, a control valve for controlling the admission of a motive fluid to said high pressure turbine stage, an intercept valve for controlling the admission of motive fluid to said low pressure turbine stage, and a speed governor for said control and intercept valves, the improvement comprising:
  • a braking control valve for controlling the admission of motive fluid to said reverse torque generating turbine
  • a control means for controlling said braking control valve to prevent an undesirable rotational overspeed of said high and low pressure turbine stages.
  • control means comprises an auxiliary speed governor for causing said braking valve to open upon the turbine speed increasing beyond a predetermined value.
  • control means comprises an auxiliary speed governor for causing said braking valve to open upon the turbine speed increasing beyond a predetermined value.
  • control means comprises a differential element for detecting a closing of said intercept valve at a relatively high rate of speed.
  • control means comprises a differential element for detecting a closing of said intercept valve at a relatively high rate of speed.
  • control means comprises:
  • dashpot means for detecting an increase of said turbine speed at a high rate and being responsive thereto for operating said pilot valve to cause said braking control valve to be opened, but permitting said braking control valve to be slowly closed by said biasing means if said preselected level of speed is not exceeded.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Control Of Turbines (AREA)
US149640A 1970-06-04 1971-06-03 Elastic fluid turbine system Expired - Lifetime US3692419A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3859007A (en) * 1972-11-06 1975-01-07 Siemens Ag Apparatus for monitoring and limiting the speed of turbines
US4019390A (en) * 1976-04-22 1977-04-26 Westinghouse Electric Corporation System and method for complete on line testing of a mechanical overspeed trip channel associated with an electrohydraulic emergency trip system for a turbine power plant
WO2006103270A1 (de) * 2005-03-30 2006-10-05 Alstom Technology Ltd Verfahren zum anfahren einer turbinenanlage mit zuschaltbarem nebenstrang

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3427464A (en) * 1964-08-13 1969-02-11 Parsons & Co Ltd C A Speed governing systems for steam turbines

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3427464A (en) * 1964-08-13 1969-02-11 Parsons & Co Ltd C A Speed governing systems for steam turbines

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3859007A (en) * 1972-11-06 1975-01-07 Siemens Ag Apparatus for monitoring and limiting the speed of turbines
US4019390A (en) * 1976-04-22 1977-04-26 Westinghouse Electric Corporation System and method for complete on line testing of a mechanical overspeed trip channel associated with an electrohydraulic emergency trip system for a turbine power plant
WO2006103270A1 (de) * 2005-03-30 2006-10-05 Alstom Technology Ltd Verfahren zum anfahren einer turbinenanlage mit zuschaltbarem nebenstrang
US7614239B2 (en) 2005-03-30 2009-11-10 Alstom Technology Ltd Turbine installation having a connectable auxiliary group

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GB1288015A (xx) 1972-09-06

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