US3813884A - System for controlling a steam turbine at start-up - Google Patents

System for controlling a steam turbine at start-up Download PDF

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Publication number
US3813884A
US3813884A US00294763A US29476372A US3813884A US 3813884 A US3813884 A US 3813884A US 00294763 A US00294763 A US 00294763A US 29476372 A US29476372 A US 29476372A US 3813884 A US3813884 A US 3813884A
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Prior art keywords
turbine
steam
valve
conduit
flow
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US00294763A
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English (en)
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M Ishikawa
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Mitsubishi Heavy Industries Ltd
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Mitsubishi Heavy Industries 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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being only of turbine type the turbines having inter-stage steam heating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

Definitions

  • This invention relates to a system for controlling a steam turbine and more particularly to a system for controlling a reheat turbine during start-up and at low loads.
  • reheat steam turbines have a plurality of inlet nozzle chambers disposed circumferentially adjacent a first stage of rotating blades, and during start-up and at low loads the quantity of motive steam being supplied to'the turbine is small so that motive steam is only flowing through one nozzle chamber. This results in nonuniform heating of the turbine, which causes thermal stress, which reduces the life expectancy of the turbine.
  • the sequentially operable governing valves are all opened allowing motive steam to be admitted to all portions of the first stage and the main steam throttle valve is operated to control the speed of the turbine.
  • This method of operation is referred to as full arc admission and is utilized during start-up and when operating at low loads.
  • the temperature of the motive steam in the first stage of the turbine fluctuates, as each mode of operation produces different steam temperatures as the throttling characteristics and distribution of the steam varies considerably for each mode of operation.
  • This control system also comprises a control valve for controlling the flow of motive steam flowing through the reheat conduit and a device responsive to the condition of the motive steam, after it passes through at least one portion of the first turbine, to control the control valve in the reheat conduit, whereby the temperature of the motive steam exhausted from the first turbine remains generally constant irrespective of whether the quantity of motive steam is controlled by the main steam throttling valve or by the sequentially operable control valve thereby minimizing the thermal shock resulting from switching from one mode of control to the other.
  • FIG. 1 is a schematic diagram of nozzles chambers for a turbine having a plurality of sequentially operable control valves
  • FIG. 2 is a graph showing the operation of the turbine with partial'and full part admission'su'perimposed upon a portion of a Mollier diagram
  • FIG. 3 is a flow diagram for a reheat turbine
  • FIG. 4 is a schematic diagram of a reheat turbine incorporating a control system made in accordance with this invention.
  • FIG. 5 is a schematic diagram of a conroller utilized in this invention.
  • a FIG. 6 is a temperature-time graph showing the advantages of this invention.
  • a high pressure turbine 9 The exhaust .fromthe high. pressure turbine 9 flows through a reheat conduit 11 to I a reheater 13, wherein additional heat is added to the partially used motive steam to increase its temperature.
  • the reheat conduit 11 directs the reheated motive steam through a stop valve 15 an intercept valve .17 and then into an intermediate pressure turbine 19.
  • the exhaust from the intermediate pressure turbine 19 flows through'a crossover pipe 21 to adouble flow low pressure turbine 23.
  • the exhaust from the low pressure turbine is condensed in a condenser 25.
  • the condensate is picked up from a hot well by a condensate pump 27, pumped through two low pressure feedwater heaters 29 and 31, respectively, and then to a boiler feed pump 33 which pumps the condensate through two high pressure feedwater heaters 35and 37 and then into the boiler l forming a closedcycle.
  • Turbines 9, l9 and 23 are disposed in a tandem compound arrangement and are directly connected by a common shaft 38 to a generator 39, which produceselectrical power and provides the load for the turbine.
  • the stop valve 5 and the control valve 7 are adapted to independently respond to the speed and load so that either may be .utilized to control the flow of motive steam to the turbine.
  • the stop valve 5 may be one or more valves, which are operable to provide motive steam throttling means
  • the control valve 7 may be a sequentially operable control or governing valve meanscomprising a plurality of sequentially operable valves 7a, b, c, d, e, f, g and h disposed to regulate the flow of motive steam to a plurality of nozzle chambers 41a, b, c, d, e, f, g and h disposed circumferentially adjacent a first stage of rotatable blades 43, as shown in FIGS. 1 and 3.
  • the control system for the turbine comprises the intercept valve 17 which has a servomotor 45 or other means for regulating the opening and closing thereof in order to regulate the flow of motive fluid as steam through the reheat conduit 11.
  • the flow of motive steam through the reheater conduit 11 may also be controlled or regulated by a bypass valve 47, which has a servomotor 49 cooperatively associated therewith, or other bypass means which direct the motivestearn around the reheat stop valve 15 and the intercept valve 17.
  • a signal which may be either pneumatic, electric or hydraulic and sends it to a controller 55 or 57 which in turn sends a signal to the servomotor 45 or-49 to open and close the intercept valve 17 or the bypass valve 47, respectively, to regulate or control the quantity of motive steam flowing from the exhaust of the first or high pressure turbine 9 and through the reheater l3 and reheater conduit 11.
  • the controllers 55 and 57 may be pneumatic, electric or hydraulic, however, the ones shown in F IG. are hydraulic and comprise three compartments 61, 62 and 63.
  • a bellows, diaphragm or other pressure sensitive or pressure responsive means 65 is disposed between the compartments 61 and 62.
  • Cooperatively associated with the pressure-responsive means 65 is a valve stem 67 which has a valve plug.69 connected thereto.
  • the valve plug 69' is cooperatively associated with an opening 71 between chambers 62 and 63 so as to regulate the flow of fluid'therebetween.
  • the means responsive to a condition of the motive steam may be pressure or temperature responsive means 51 for 53, respectively, and the signal they produce is a varied pressure, which acts upon the pressure responsive means 65to open and close the valve plug 69,which when opened,
  • Solenoid valves 81 and 83 are disposed in conduits between the controller 55 and 57 and the servomotors 45 and 49, respectively, so that the control system can .beremoved from service automatically or manually when the load exceeds some predetermined value.
  • a solenoid valve 85 is provided to drain high pressure control fluid being supplied thereto to drain to cause the intercept valve to close rapidly.
  • a solenoid'valve 87 is provided to shut off pressurized control fluid from other sources when the intercept valve is being utilized to regulate the flow of motor fluid through the reheat conduit 11.
  • P represents the pressure of .the steam in the main steam line and t represents its temperature.
  • P, I represents the pressure and temperature of the steam after it has passed .through the wide opened main steam throttling valve 5 and through the partially opened sequentially operable governing valve 7. Since no work has been done by the steam as it passes through the valves the Rankine cycle efficiency would be approximately zero and the enthalpy would be essentially equal to the enthalpy at the conditions P.
  • P, t represents the pressure and temperature
  • the partially P t represents the pressure and temperature, respectively, of steam after it has passed through 'a partially opened main steam throttle valve 5 and a fully opened sequentially operable governing valve 7 assuming a Rankine Cycle Efficiency of zero
  • P ti represents the condition of this steam after it has passed through the first stage 43 of the turbine 9 assuming a Rankine Efficiency of approximately 65 percent.
  • P 1 represents the condition of the steam after passing through the wide opened main steam throttling valve 5 and a wide opened sequentially operable governing valve-and through the first'stage 43 of the turbine 9 assuming generally 65 percent Rankine Efficiency of the first stage of the turbine.
  • Line tc represents a constant temperature line and lines Pc ,.Pc and Pe represent constant pressure lines.
  • the temperature of the steam after it leaves the first stage can be adjusted so that there is no material temperature difference when switching from one mode of operation to the other.
  • FIG 6 shows the temperature of the steam after the first stage of the high pressure turbine as the function of time from start-up.
  • the solid line 91 represents the temperature versus time curve for control systems previously used and the dotted line 93 represents the temperature time curve for control systems made in accordance with this invention.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Turbines (AREA)
US00294763A 1971-10-21 1972-10-03 System for controlling a steam turbine at start-up Expired - Lifetime US3813884A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46082844A JPS5210161B2 (is") 1971-10-21 1971-10-21

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132076A (en) * 1975-08-22 1979-01-02 Bbc Brown, Boveri & Company Limited Feedback control method for controlling the starting of a steam turbine plant
US6085829A (en) * 1998-03-04 2000-07-11 Solo Enery Corporation Regenerator type heat exchanger
US20110014099A1 (en) * 2009-07-17 2011-01-20 Umicore Ag & Co.Kg Particulate filter with hydrogen sulphide block function
US8671688B2 (en) * 2011-04-13 2014-03-18 General Electric Company Combined cycle power plant with thermal load reduction system
US10358974B2 (en) * 2017-10-25 2019-07-23 Calnetix Technologies, Llc Closed-loop thermal cycle expander bypass flow control

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3546121B2 (ja) * 1997-02-25 2004-07-21 三菱重工業株式会社 管路内流体圧制御装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3097488A (en) * 1961-11-03 1963-07-16 Gen Electric Turbine control system
US3241322A (en) * 1963-02-11 1966-03-22 Gilbert Associates Turbine steam admission controls
US3286466A (en) * 1964-04-24 1966-11-22 Foster Wheeler Corp Once-through vapor generator variable pressure start-up system
US3338053A (en) * 1963-05-20 1967-08-29 Foster Wheeler Corp Once-through vapor generator start-up system
US3577733A (en) * 1968-07-16 1971-05-04 Gen Electric Rapid loading of steam turbines

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3097488A (en) * 1961-11-03 1963-07-16 Gen Electric Turbine control system
US3241322A (en) * 1963-02-11 1966-03-22 Gilbert Associates Turbine steam admission controls
US3338053A (en) * 1963-05-20 1967-08-29 Foster Wheeler Corp Once-through vapor generator start-up system
US3286466A (en) * 1964-04-24 1966-11-22 Foster Wheeler Corp Once-through vapor generator variable pressure start-up system
US3577733A (en) * 1968-07-16 1971-05-04 Gen Electric Rapid loading of steam turbines

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132076A (en) * 1975-08-22 1979-01-02 Bbc Brown, Boveri & Company Limited Feedback control method for controlling the starting of a steam turbine plant
US6085829A (en) * 1998-03-04 2000-07-11 Solo Enery Corporation Regenerator type heat exchanger
US20110014099A1 (en) * 2009-07-17 2011-01-20 Umicore Ag & Co.Kg Particulate filter with hydrogen sulphide block function
US8709365B2 (en) * 2009-07-17 2014-04-29 Umicore Ag & Co. Kg Particulate filter with hydrogen sulphide block function
US8671688B2 (en) * 2011-04-13 2014-03-18 General Electric Company Combined cycle power plant with thermal load reduction system
US10358974B2 (en) * 2017-10-25 2019-07-23 Calnetix Technologies, Llc Closed-loop thermal cycle expander bypass flow control

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Publication number Publication date
JPS4848805A (is") 1973-07-10
JPS5210161B2 (is") 1977-03-22

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