EP1965043B1 - Steam turbine cycle - Google Patents
Steam turbine cycle Download PDFInfo
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- EP1965043B1 EP1965043B1 EP06843008.1A EP06843008A EP1965043B1 EP 1965043 B1 EP1965043 B1 EP 1965043B1 EP 06843008 A EP06843008 A EP 06843008A EP 1965043 B1 EP1965043 B1 EP 1965043B1
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- Prior art keywords
- feed
- steam
- cycle
- turbine
- water
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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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
- F01K7/34—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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
- F01K7/40—Use of two or more feed-water heaters in series
-
- 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
- F01K17/00—Using steam or condensate extracted or exhausted from steam engine plant
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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steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating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
-
- 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
- F01K7/34—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 of extraction or non-condensing type; Use of steam for feed-water heating
-
- 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
- F01K7/34—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 of extraction or non-condensing type; Use of steam for feed-water heating
- F01K7/38—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 of extraction or non-condensing type; Use of steam for feed-water heating the engines being of turbine type
Definitions
- the present invention relates to a steam turbine cycle having an improved cycle thermal efficiency.
- the superheated steam may be an ultra supercritical pressure fluid.
- the main steam 16 which has flown into a high pressure turbine 1, expands and flows therethrough, while a pressure and a temperature thereof are lowered.
- the steam expands and flows through the intermediate pressure turbine 2, while a pressure and a temperature thereof are lowered. Then, the steam flows into a low pressure turbine 3.
- the steam expands and flows through the low pressure turbine 3, while a pressure and a temperature thereof are lowered. A part of the steam often becomes a saturated steam as a liquid water.
- the saturated steam is cooled by a condenser 10 by using sea water or atmospheric air 23, so that the saturated steam becomes a condensed water 25.
- the condensed water 25 is sent to a feed heater 6 by a condensing pump 11 to become a boiler feed water 14.
- the intermediate pressure turbine 2 and the low pressure turbine 3 constitute a reheating turbine 24.
- Fig. 1 eight feed heaters 6 are illustrated.
- the boiler feed water 14 is heated by a bleed steam 20 bled from bleeding positions 31 in channels of the intermediate pressure turbine 2 and the low pressure turbine 3.
- a bleed steam of a higher pressure is flown into the feed heater 6 of a higher pressure.
- the low pressure turbine 3 is illustrated as a double flow pressure turbine, and a steam is bled from only one of the low pressure turbine 3. However, a steam is actually bled from both the low pressure turbines 3 and merged. The merged steam flows into the feed heater 6. It is possible to bleed a steam from one of the low pressure turbines 3, depending on the feed heater 6.
- the feed heater 6 is classified into a feed heater of a surface type and a feed heater of a mixing type.
- a feed heater of a surface type the bleed steam 20 is condensed by exchanging heats with a feed water via a heat transmission surface to become a drain water 15.
- the drain water 15 sequentially flows from the feed heater 6 of a higher pressure to the feed heater 6 of a lower pressure.
- the drain water 15 in the feed heater 6 of the lowest pressure flows into the condenser 10.
- the drain water 15 may be merged into a feed water by a drain water pump 13.
- a bleed steam is directly mixed with a feed water to heat the same.
- a deaerator 9 for deaerating oxygen or the like which is dissolved in a feed water is included in the feed heater of a mixing type.
- a feed pump 12 In order to send a feed water to a feed heater 6 of a higher pressure, a feed pump 12 is disposed directly downstream of the feed heater of a mixing type.
- a bleed steam to the feed heater of a mixed type is an intermediate-pressure turbine exhaust bleed steam 32, another steam is possible.
- the deaerator 9 may be omitted. Even when the deaerator 9 is omitted, the feed pump 12 is disposed on a suitable position between the plurality of feed heaters 6. A feed water sequentially heated in all of the feed heaters 6 flows into the boiler 4.
- the high pressure turbine 1, the intermediate pressure turbine 2, and the low pressure turbine 3 are connected to each other by a single rotation shaft 19, and are connected to a generator 18.
- a steam expands in the high pressure turbine 1, the intermediate pressure turbine 2, and the high pressure turbine 3, so that enthalpy of the steam is converted into a shaft power, whereby electric power is generated by the generator 18. It is possible not to connect the respective turbines to the single generator 18 by connecting the turbines by the single rotation shaft 19.
- Fig. 1 illustrates the low pressure turbine 3 as a double flow pressure turbine in which a flow-in steam is divided into two and the divided steams flow into the two low pressure turbines 3.
- the flow-in steam may be divided into four, or may not be divided.
- the intermediate pressure turbine 2 is illustrated as a single flow pressure turbine, the intermediate pressure turbine 2 may be a double flow pressure turbine.
- Fig. 1 shows that the intermediate pressure turbine 2 and the low pressure turbine 3 are separated turbines, a single reheating turbine 24 is possible.
- Both of a regenerative cycle using the bleed steam 20, and a reheating cycle in which the high-pressure exhaust steam 21 heated by the reheater 5 flows into the reheating turbine 24, are modified Rankine cycles, and improve a thermal efficiency from a simple Rankine cycle.
- a thermal efficiency is substantially equal to a value obtained by dividing an amount of generated power by an amount of boiler heat input.
- a cycle thermal efficiency varies depending on a temperature and a flowrate of each bleed steam 20.
- a temperature of steam has been recently more and more increased, whereby a cycle thermal efficiency has been improved.
- Non-Patent Document "Steam Turbine Performance and Economics" written by Bartlett
- Patent document US-5836162 and WO-80/00864 describes a steam turbine cycle wherein a temperature increase ratio between a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine and an average of feed-water temperature increase in feed heaters other than the first feed heater is lower than 1.8.
- the object of the present invention is to provide a steam turbine cycle of an improved cycle thermal efficiency.
- the invention according to claim 1 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5.
- the invention according to claim 2 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed waters in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5.
- the invention according to claim 3 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
- a steam temperature at an outlet of the boiler is 590°C or more, and a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in feed heaters other than the first feed heater; falls within 1.9 - 3.5.
- the invention according to claim 4 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed heaters other than the first feed heater; falls within 1.9 - 3.5.
- Fig. 1 is a view of the first embodiment of the present invention.
- the steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating turbine 24, a boiler 4, feed heaters 6 for heating a feed water to the boiler 4 by a bleed steam from the high pressure turbine 1 and the reheating turbine 24, a feed pump 12, and a condenser 10.
- the steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle.
- a steam temperature at an outlet of the boiler 4 is 590°C or above.
- feed-water temperature increases in the first feed heater 7 and the second feed heaters 8 can be adjusted.
- temperatures of the high-pressure turbine exhaust bleed steam 22 and an intermediate-pressure turbine exhaust bleed steam 32 exhaust specifications of the high pressure turbine 1 and the intermediate pressure turbine 2 have to be changed.
- a feed water temperature at an inlet of the boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that the temperature increase ratio falls within 1.9 - 3.5.
- the temperature increase ratio between a feed-water temperature increase in the first feed heater 7 and an average of feed-water temperature increases in the second feed heaters 8 may vary within a certain range, depending on the number of the feed heaters 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on.
- the non-patent document describes that an optimum specific enthalpy ratio is 1.8.
- a specific enthalpy increase ratio of 1.8 is not practical as to a range of a temperature increase ratio.
- An output of the steam turbine is a sum of "a heat drop, i.e., a specific enthalpy decrease amount x steam mass flowrate" at each stage of each turbine.
- a heat drop i.e., a specific enthalpy decrease amount x steam mass flowrate
- an efficiency of a regenerative cycle can be improved, when a temperature at the inlet of the boiler 4 of the boiler feed water 14 is higher. Namely, both the efficiencies have to be considered.
- the high-pressure turbine exhaust bleed steam 22 is a steam that has a low specific enthalpy although a pressure thereof is relatively high.
- the high-pressure turbine exhaust bleed steam 22 is not a bleed steam bled from a steam which has been heated by the reheater 5.
- a thermal efficiency of the overall cycle can be improved.
- a temperature increase ratio has a certain optimum value at which a thermal efficiency is maximized.
- This optimum value is preferable when the temperature increase ratio is sufficiently higher than 1.
- This optimum value varies depending on conditions of the main steam 16, and it is presumed that the value becomes higher as to a steam of a higher temperature.
- a steam turbine cycle in this embodiment includes a high pressure a high pressure turbine 1, a reheating turbine 24, a boiler 4, feed heaters 6 for heating a feed water to the boiler 4 by a bleed steam from the high pressure turbine 1 and the reheating turbine 24, a feed pump 12, and a condenser 10.
- the steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle.
- a steam temperature at an outlet of the boiler 4 is 590°C or above.
- each bleed steam 20 and each bleed position 31 By adjusting a flowrate of each bleed steam 20 and each bleed position 31, specific enthalpy increases in the feed waters in the first feed heater 7 and the second feed heaters 8 can be adjusted.
- exhaust specifications of the high pressure turbine 1 and the intermediate pressure turbine 2 have to be changed.
- a feed water temperature at an inlet of the boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- a specific enthalpy increase ratio may vary within a certain range, depending on the number of the feed heaters 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on.
- the non-patent document describes that an optimum specific enthalpy ratio is 1.8. However, this document does not refer to a temperature of the main steam 16. Thus, since a different temperature of the main steam 16 is assumed, an optimum value of a specific enthalpy increase ratio is considered to be different.
- a specific enthalpy increase ratio has a certain optimum value at which a thermal efficiency is optimized. This optimum value is preferable when the specific enthalpy increase ratio is sufficiently higher than 1. This optimum value varies depending on conditions of the main steam 16, and it is presumed that the value becomes higher as to a steam of a higher temperature.
- the steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating turbine 24, a boiler 4, a feed heaters 6 for heating a feed water to the boiler 4 by a bleed steam from the high pressure turbine 1 and the reheating turbine 24, a feed pump 12, and a condenser 10.
- the steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle.
- a steam temperature at an outlet of the boiler 4 is 590°C or more.
- the feed heaters other than the first heed heater 7 mean the second feed heaters 8 where a pressure of the feed water is lower than that of the first feed heater 7, and a third feed heater 26 where a pressure of the feed water is higher than that of the first feed heater 7.
- the third feed heater 26 heats a feed water by a bleed steam from the high pressure turbine 1.
- feed-water temperature increases in the first feed heater 7, the second feed heaters 8, and the third feed heater 26 can be adjusted.
- temperatures of the high-pressure turbine exhaust bleed steam 22 and an intermediate-pressure turbine exhaust bleed steam 32 exhaust specifications of the high pressure turbine 1 and the intermediate pressure turbine 2 have to be changed.
- a feed water temperature at an inlet of the boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5.
- a feed temperature increase ratio between: a feed-water temperature increase in the first heater 7; and an average of feed-water temperature increases in the feed heaters 8 and 26 other than the first feed heater 7; may vary within a certain range, depending on the number of the feed heater 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on.
- FIG. 1 A fourth embodiment of the present invention is described with reference to Fig. 1 .
- the steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating turbine 24, a boiler 4, feed heaters 6 for heating a feed water to the boiler 4 by a bleed steam from the high pressure turbine 1 and the reheating turbine 24, a feed pump 12, and a condenser 10.
- the steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle.
- a steam temperature at an outlet of the boiler 4 is 590°C or more.
- each bleed steam 20 and each bleed position 31 By adjusting a flowrate of each bleed steam 20 and each bleed position 31, specific enthalpy increases in feed waters in the first feed heater 7, the second feed heaters 8, and the third feed heater 26 can be adjusted.
- specific enthalpies of the high-pressure turbine exhaust bleed steam 22 and an intermediate-pressure turbine exhaust bleed steam 32 exhaust specifications of the high pressure turbine 1 and the intermediate pressure turbine 2 have to be changed.
- a feed water temperature at an inlet of the boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- a specific enthalpy increase ratio between: a specific enthalpy increase of a feed water in the first feed heater 7; and an average of specific enthalpy increases of feed waters in the feed heaters 8 and 26 other than the first feed heater 7 may vary within a certain range, depending on the number of the feed heaters 6, mechanical differences in the steam turbines such as an exhaust loss, a value corresponding to a power generation output in a power plant, differences in minute structures, and so on.
- a fifth embodiment of the present invention is described with reference to Fig 1 .
- the fifth embodiment shown in Fig. 1 differs from the first embodiment in that feed-water temperature increases in the second feed heaters 8 are calculated in consideration of a feed-water temperature increase by a feed pump 12.
- Other structures of the fifth embodiment are substantially the same as those of the first embodiment.
- a feed water temperature at an inlet of a boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was fond that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5.
- a temperature increase ratio may vary within a certain range, under influences of a heat generation difference caused by a mechanical difference in the feed pump 12.
- FIG. 1 differs from the first embodiment in that feed-water specific enthalpy increases in the second feed heaters 8 are calculated in consideration of a feed-water specific enthalpy increase by a feed pump 12.
- Other structures of the sixth embodiment are substantially the same as those of the first embodiment.
- the feed pump 12 increases a pressure of a feed water, and simultaneously heats the feed water, as described in the third embodiment, so that a specific enthalpy of the feed water is increased.
- a specific enthalpy increase an average specific enthalpy increase in each of the second feed heaters 8 is calculated.
- This embodiment can be carried out, in the above-described fourth embodiment, by calculating specific enthalpy increases of feed waters in the feed heaters 8 and 26 other than a first feed heater 7, in consideration of a specific enthalpy increase in a feed water by the feed pump 12.
- a feed water temperature at an inlet of a boiler 4 is generally defined by the boiler 4.
- a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- a specific enthalpy increase ratio may vary within a certain range, under influences of a heat generation difference caused by a mechanical difference in the feed pump 12.
- a cycle thermal efficiency can be increased, similarly to the second and fourth embodiments.
- the eight feed heaters 6 in total are used and a cycle structure is made such that a temperature increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, the number of the feed heaters 6 is preferably eight from an economical point of view.
- Fig. 1 steam is bled at two positions from the intermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from the low pressure turbine 3.
- the total number of the bleed positions is six, the number and the positions are not limited thereto.
- a bleed steam to the aerator 9 is the intermediate-pressure turbine exhaust bleed steam 32, but is not limited thereto.
- the number of the feed heaters 6 being limited to eight, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5.
- the eight feed heaters 6 in total are used and a cycle structure is made such that a specific enthalpy increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, the number of the feed heaters 6 is preferably eight from an economical point of view.
- Fig. 1 steam is bled at two positions from the intermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from the low pressure turbine 3.
- the total number of the bleed positions is six, the number and the positions are not limited thereto.
- a bleed steam to the aerator 9 is the intermediate-pressure turbine exhaust bleed steam 32, but is not limited thereto.
- the number of the feed heaters 6 being limited to eight, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- FIG. 2 the same parts as those of Fig. 1 are shown by the same reference numbers, and their detailed description is omitted.
- the nine feed heaters 6 in total are used, and a cycle structure is made such that a temperature increase ratio falls within 1.9 - 3.5.
- the number of the feed heaters 6 is preferably eight from an economical point of view, there is a case in which the number of the feed heaters 6 is preferably nine, with a view to more increasing an efficiency, an output, and a temperature of a main steam.
- Fig. 2 steam is bled at three positions from an intermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from a low pressure turbine 3.
- the total number of the bleed positions is seven, the number and the positions are not limited thereto.
- a bleed steam to a deaerator 9 is an intermediate pressure turbine exhaust steam 32, but is not limited thereto.
- the number of the feed heaters 6 being limited to nine, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5.
- the nine feed heaters 6 in total are used, and a cycle structure is made such that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- the number of the feed heaters 6 is preferably eight from an economical point of view, there is a case in which the number of the feed heaters 6 is preferably nine, with a view to more increasing an efficiency, an output, and a temperature of a main steam.
- Fig. 2 steam is bled at three positions from an intermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from a low pressure turbine 3.
- the total number of the bleed positions is seven, the number and the positions are not limited thereto.
- a bleed steam to a deaerator 9 is an intermediate pressure turbine exhaust steam 32, but is not limited thereto.
- the number of the feed heaters 6 being limited to nine, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5.
- a cycle structure is made such that a steam temperature at an outlet of the boiler 4 is 600°C or more. This is because, when a temperature of the main steam 16 is 600°C or above, a more significant effect can be expected. Namely, an effect of improving a cycle thermal efficiency due to an increased temperature of the main steam 16 is not damaged by set conditions of a bleed steam 20 but can be fully exerted.
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- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
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- Engine Equipment That Uses Special Cycles (AREA)
- Control Of Turbines (AREA)
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Description
- The present invention relates to a steam turbine cycle having an improved cycle thermal efficiency.
- An example of a steam turbine cycle used in a heat power plant or the like is described as a conventional art with reference to
Fig. 1 . - A boiler feed water 14 heated by a
boiler 4 with the use of fuel combustion heat so as to generate a superheated steam (hereinafter referred to as "main steam 16") of a sufficiently high temperature. The superheated steam may be an ultra supercritical pressure fluid. - The
main steam 16, which has flown into a high pressure turbine 1, expands and flows therethrough, while a pressure and a temperature thereof are lowered. - Most part of a high-pressure
turbine exhaust steam 21, which has flown out from the high pressure turbine 1, flows into areheater 5, and becomes there a reheatedsteam 17 of a higher temperature. The reheatedsteam 17 flows into anintermediate pressure turbine 2. - The steam expands and flows through the
intermediate pressure turbine 2, while a pressure and a temperature thereof are lowered. Then, the steam flows into alow pressure turbine 3. - The steam expands and flows through the
low pressure turbine 3, while a pressure and a temperature thereof are lowered. A part of the steam often becomes a saturated steam as a liquid water. The saturated steam is cooled by acondenser 10 by using sea water or atmospheric air 23, so that the saturated steam becomes a condensedwater 25. The condensedwater 25 is sent to afeed heater 6 by acondensing pump 11 to become a boiler feed water 14. Theintermediate pressure turbine 2 and thelow pressure turbine 3 constitute a reheatingturbine 24. - In
Fig. 1 , eightfeed heaters 6 are illustrated. The boiler feed water 14 is heated by ableed steam 20 bled frombleeding positions 31 in channels of theintermediate pressure turbine 2 and thelow pressure turbine 3. A bleed steam of a higher pressure is flown into thefeed heater 6 of a higher pressure. - In
Fig. 1 , thelow pressure turbine 3 is illustrated as a double flow pressure turbine, and a steam is bled from only one of thelow pressure turbine 3. However, a steam is actually bled from both thelow pressure turbines 3 and merged. The merged steam flows into thefeed heater 6. It is possible to bleed a steam from one of thelow pressure turbines 3, depending on thefeed heater 6. - The
feed heater 6 is classified into a feed heater of a surface type and a feed heater of a mixing type. In a feed heater of a surface type, thebleed steam 20 is condensed by exchanging heats with a feed water via a heat transmission surface to become adrain water 15. In principle, thedrain water 15 sequentially flows from thefeed heater 6 of a higher pressure to thefeed heater 6 of a lower pressure. Thedrain water 15 in thefeed heater 6 of the lowest pressure flows into thecondenser 10. Thedrain water 15 may be merged into a feed water by adrain water pump 13. - In the feed heater of a mixing type, a bleed steam is directly mixed with a feed water to heat the same. A
deaerator 9 for deaerating oxygen or the like which is dissolved in a feed water is included in the feed heater of a mixing type. - In order to send a feed water to a
feed heater 6 of a higher pressure, afeed pump 12 is disposed directly downstream of the feed heater of a mixing type. InFig. 1 , although a bleed steam to the feed heater of a mixed type is an intermediate-pressure turbine exhaust bleedsteam 32, another steam is possible. Thedeaerator 9 may be omitted. Even when thedeaerator 9 is omitted, thefeed pump 12 is disposed on a suitable position between the plurality offeed heaters 6. A feed water sequentially heated in all of thefeed heaters 6 flows into theboiler 4. - In
Fig. 1 , the high pressure turbine 1, theintermediate pressure turbine 2, and thelow pressure turbine 3 are connected to each other by asingle rotation shaft 19, and are connected to agenerator 18. A steam expands in the high pressure turbine 1, theintermediate pressure turbine 2, and thehigh pressure turbine 3, so that enthalpy of the steam is converted into a shaft power, whereby electric power is generated by thegenerator 18. It is possible not to connect the respective turbines to thesingle generator 18 by connecting the turbines by thesingle rotation shaft 19. -
Fig. 1 illustrates thelow pressure turbine 3 as a double flow pressure turbine in which a flow-in steam is divided into two and the divided steams flow into the twolow pressure turbines 3. The flow-in steam may be divided into four, or may not be divided. InFig. 1 , although theintermediate pressure turbine 2 is illustrated as a single flow pressure turbine, theintermediate pressure turbine 2 may be a double flow pressure turbine. In addition, althoughFig. 1 shows that theintermediate pressure turbine 2 and thelow pressure turbine 3 are separated turbines, asingle reheating turbine 24 is possible. - Both of a regenerative cycle using the
bleed steam 20, and a reheating cycle in which the high-pressure exhaust steam 21 heated by thereheater 5 flows into the reheatingturbine 24, are modified Rankine cycles, and improve a thermal efficiency from a simple Rankine cycle. In a power generation plant, a thermal efficiency is substantially equal to a value obtained by dividing an amount of generated power by an amount of boiler heat input. - In addition to a cycle structure, a cycle thermal efficiency varies depending on a temperature and a flowrate of each bleed
steam 20. In particular, in accordance with advancement of a material against a high temperature, a temperature of steam has been recently more and more increased, whereby a cycle thermal efficiency has been improved. However, there still is a room for approving a cycle structure under high temperature conditions of steam. - The below non-patent document describes that "an optimum performance is obtained when an increase in enthalpy of a certain heater caused by a bleed steam from a reheating point is 1.8 times an average increase in enthalpy in heaters of a pressure lower than that of the certain heater". Non-Patent Document: "Steam Turbine Performance and Economics" written by Bartlett
- Patent document
US-5836162 andWO-80/00864 - The object of the present invention is to provide a steam turbine cycle of an improved cycle thermal efficiency.
- The invention according to claim 1 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5.
- The invention according to
claim 2 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed waters in second feed heaters where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5. - The invention according to
claim 3 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, - wherein a steam temperature at an outlet of the boiler is 590°C or more, and a temperature increase ratio between: a feed-water temperature increase in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in feed heaters other than the first feed heater; falls within 1.9 - 3.5.
- The invention according to
claim 4 is a steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle, wherein a steam temperature at an outlet of the boiler is 590°C or more, and a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed heaters other than the first feed heater; falls within 1.9 - 3.5. - According to the present invention, there can be provided a steam turbine cycle of an improved cycle thermal efficiency.
-
-
Fig. 1 is a schematic view of first to eighth embodiments and an eleventh embodiment of a steam turbine cycle of the present invention, and a conventional art; -
Fig. 2 is a schematic view of ninth to eleventh embodiments of a steam turbine cycle of the present invention; and -
Fig. 3 is a schematic view showing a relationship between a temperature increase ratio and a thermal efficiency. - A first embodiment of a steam turbine cycle of the present invention is described below with reference to the drawings.
Fig. 1 is a view of the first embodiment of the present invention. - The steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating
turbine 24, aboiler 4,feed heaters 6 for heating a feed water to theboiler 4 by a bleed steam from the high pressure turbine 1 and the reheatingturbine 24, afeed pump 12, and acondenser 10. The steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle. - A steam temperature at an outlet of the
boiler 4 is 590°C or above. A temperature increase ratio between: a feed-water temperature increase in a first feed heater 7 corresponding to a bleed steam (high-pressure turbine exhaust bleed steam) 22 from a high-pressureturbine exhaust steam 21; and an average of feed-water temperature increases insecond feed heaters 8 where a pressure of the feed water is lower than that of the first feed heater 7; falls within 1.9 - 3.5. - By adjusting a flowrate of each bleed
steam 20 and each bleedposition 31, feed-water temperature increases in the first feed heater 7 and thesecond feed heaters 8 can be adjusted. In order to vary temperatures of the high-pressure turbineexhaust bleed steam 22 and an intermediate-pressure turbineexhaust bleed steam 32, exhaust specifications of the high pressure turbine 1 and theintermediate pressure turbine 2 have to be changed. - A feed water temperature at an inlet of the
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that the temperature increase ratio falls within 1.9 - 3.5. - The temperature increase ratio between a feed-water temperature increase in the first feed heater 7 and an average of feed-water temperature increases in the
second feed heaters 8 may vary within a certain range, depending on the number of thefeed heaters 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on. - As described above, the non-patent document describes that an optimum specific enthalpy ratio is 1.8. However, in a general power plant, a specific enthalpy increase ratio of 1.8 is not practical as to a range of a temperature increase ratio.
- A reason of this phenomenon is presumed as follows.
- An output of the steam turbine is a sum of "a heat drop, i.e., a specific enthalpy decrease amount x steam mass flowrate" at each stage of each turbine. Thus, it is more efficient when a steam is bled from a position of a lower specific enthalpy as much as possible, because the boiler feed water 14 is heated after the steam turbine works. On the other hand, an efficiency of a regenerative cycle can be improved, when a temperature at the inlet of the
boiler 4 of the boiler feed water 14 is higher. Namely, both the efficiencies have to be considered. - When a temperature of the inlet of the
boiler 4 is determined, there is required a steam of a saturated temperature which is substantially the same as the inlet temperature of theboiler 4 of thefeed heater 26 of the highest steam pressure. In this manner, a pressure of thebleed steam 20 is determined.Other feed heaters 7 and 8 support stepwise the temperature increase until the temperature reaches the value. - The high-pressure turbine
exhaust bleed steam 22 is a steam that has a low specific enthalpy although a pressure thereof is relatively high. In addition, the high-pressure turbineexhaust bleed steam 22 is not a bleed steam bled from a steam which has been heated by thereheater 5. Thus, when heating of the boiler feed water 14 with the use of the enthalpy of the high-pressureexhaust bleed steam 22 is increased, a thermal efficiency of the overall cycle can be improved. - Namely, as schematically shown in
Fig. 3 , a temperature increase ratio has a certain optimum value at which a thermal efficiency is maximized. This optimum value is preferable when the temperature increase ratio is sufficiently higher than 1. This optimum value varies depending on conditions of themain steam 16, and it is presumed that the value becomes higher as to a steam of a higher temperature. - As described above, when a temperature increase ratio between: a feed-water temperature increase in the first feed heater 7 and; an average of feed-water temperature increases in the
second feed heaters 8; is set to fall within 1.9 - 3.5, a cycle thermal efficiency can be improved. - Next, a second embodiment of the present invention is described with reference to
Fig 1 . - A steam turbine cycle in this embodiment includes a high pressure a high pressure turbine 1, a reheating
turbine 24, aboiler 4,feed heaters 6 for heating a feed water to theboiler 4 by a bleed steam from the high pressure turbine 1 and the reheatingturbine 24, afeed pump 12, and acondenser 10. The steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle. - A steam temperature at an outlet of the
boiler 4 is 590°C or above. A specific enthalpy increase ratio between: a specific enthalpy increase of a feed water in a first feed heater 7 corresponding to a high-pressure turbineexhaust bleed steam 22; and an average of specific enthalpy increases of feed waters insecond feed heaters 8 where a pressure of the feed water is lower than that of the first feed heater 7; falls within 1.9 - 3.5. - By adjusting a flowrate of each bleed
steam 20 and each bleedposition 31, specific enthalpy increases in the feed waters in the first feed heater 7 and thesecond feed heaters 8 can be adjusted. In order to vary specific enthalpies of thebleed steam 20 from a high-pressure turbineexhaust bleed steam 22 and an intermediate-pressure turbineexhaust bleed steam 32, exhaust specifications of the high pressure turbine 1 and theintermediate pressure turbine 2 have to be changed. - A feed water temperature at an inlet of the
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5. - A specific enthalpy increase ratio may vary within a certain range, depending on the number of the
feed heaters 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on. - As described above, the non-patent document describes that an optimum specific enthalpy ratio is 1.8. However, this document does not refer to a temperature of the
main steam 16. Thus, since a different temperature of themain steam 16 is assumed, an optimum value of a specific enthalpy increase ratio is considered to be different. - Also in this embodiment similar to the first embodiment, as schematically shown in
Fig. 3 , a specific enthalpy increase ratio has a certain optimum value at which a thermal efficiency is optimized. This optimum value is preferable when the specific enthalpy increase ratio is sufficiently higher than 1. This optimum value varies depending on conditions of themain steam 16, and it is presumed that the value becomes higher as to a steam of a higher temperature. - As described above, when a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in the first feed heater 7 and; an average of specific enthalpy increases in feed waters in the
second feed heaters 8; is set to fall within 1.9 - 3.5, a cycle thermal efficiency can be improved. - Next, a third embodiment of the present invention is described with reference to
Fig. 1 . - The steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating
turbine 24, aboiler 4, afeed heaters 6 for heating a feed water to theboiler 4 by a bleed steam from the high pressure turbine 1 and the reheatingturbine 24, afeed pump 12, and acondenser 10. The steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle. - A steam temperature at an outlet of the
boiler 4 is 590°C or more. A temperature increase ratio between: a feed-water temperature increase in a first feed heater 7 corresponding to a high-pressure turbineexhaust bleed steam 22 and an average of feed-water temperature increases in feed heaters other than the first feed heater 7; falls within 1.9 - 3.5. - Herein, the feed heaters other than the first heed heater 7 mean the
second feed heaters 8 where a pressure of the feed water is lower than that of the first feed heater 7, and athird feed heater 26 where a pressure of the feed water is higher than that of the first feed heater 7. Thethird feed heater 26 heats a feed water by a bleed steam from the high pressure turbine 1. - By adjusting a flowrate of each bleed
steam 20 and each bleedposition 31, feed-water temperature increases in the first feed heater 7, thesecond feed heaters 8, and thethird feed heater 26 can be adjusted. In order to vary temperatures of the high-pressure turbineexhaust bleed steam 22 and an intermediate-pressure turbineexhaust bleed steam 32, exhaust specifications of the high pressure turbine 1 and theintermediate pressure turbine 2 have to be changed. - A feed water temperature at an inlet of the
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5. - A feed temperature increase ratio between: a feed-water temperature increase in the first heater 7; and an average of feed-water temperature increases in the
feed heaters feed heater 6, a mechanical difference in a steam turbine such as an exhaust loss, a value corresponding to a power generation output in a power plant, a difference in a minute structure, and so on. - As described above, when a temperature increase ratio between: a feed-water temperature increase in the first feed heater 7; and an average of feed-water temperature increases in the
feed heaters - A fourth embodiment of the present invention is described with reference to
Fig. 1 . - The steam turbine cycle in this embodiment includes a high pressure turbine 1, a reheating
turbine 24, aboiler 4,feed heaters 6 for heating a feed water to theboiler 4 by a bleed steam from the high pressure turbine 1 and the reheatingturbine 24, afeed pump 12, and acondenser 10. The steam turbine cycle in this embodiment is a single-stage reheating cycle where a working fluid is water and uses a Rankine cycle which is a regenerative cycle. - A steam temperature at an outlet of the
boiler 4 is 590°C or more. A specific enthalpy increase ratio between: a specific enthalpy increase of a feed water in a first feed heater 7 corresponding to a high-pressure turbineexhaust bleed steam 22; and an average of specific enthalpy increases of feed waters infeed heaters - By adjusting a flowrate of each bleed
steam 20 and each bleedposition 31, specific enthalpy increases in feed waters in the first feed heater 7, thesecond feed heaters 8, and thethird feed heater 26 can be adjusted. In order to vary specific enthalpies of the high-pressure turbineexhaust bleed steam 22 and an intermediate-pressure turbineexhaust bleed steam 32, exhaust specifications of the high pressure turbine 1 and theintermediate pressure turbine 2 have to be changed. - A feed water temperature at an inlet of the
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5. - A specific enthalpy increase ratio between: a specific enthalpy increase of a feed water in the first feed heater 7; and an average of specific enthalpy increases of feed waters in the
feed heaters feed heaters 6, mechanical differences in the steam turbines such as an exhaust loss, a value corresponding to a power generation output in a power plant, differences in minute structures, and so on. - As described above, when a specific enthalpy increase ratio between: a specific enthalpy increase of a feed water in the first feed heater 7; and an average of specific enthalpy increases of feed waters in the
feed heaters - Next, a fifth embodiment of the present invention is described with reference to
Fig 1 . The fifth embodiment shown inFig. 1 differs from the first embodiment in that feed-water temperature increases in thesecond feed heaters 8 are calculated in consideration of a feed-water temperature increase by afeed pump 12. Other structures of the fifth embodiment are substantially the same as those of the first embodiment. - Since the
feed pump 12 heats a feed water, a temperature of the feed water is increased. Thus, in consideration of the temperature increase, an average of a temperature increase in each ofsecond feed heaters 8 is calculated. - Alternatively, in the third embodiment, it is possible to calculate feed-water temperature increases in the
feed heaters feed pump 12. - Also in this case, since the
feed pump 12 heats a feed water, a temperature of the feed water is increased. Thus, in consideration of the temperature increase, an average of a temperature increase in each of thefeed heaters - A feed water temperature at an inlet of a
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was fond that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5. - In addition to the reason as described in the first embodiment, a temperature increase ratio may vary within a certain range, under influences of a heat generation difference caused by a mechanical difference in the
feed pump 12. - As described above, by calculating feed-water temperature increases in the
second feed heaters 8 in consideration of a temperature increase in the feed water by thefeed pump 12, and then by determining a temperature increase ratio, a cycle thermal efficiency can be increased, similarly to the first and third embodiments. - Next, a sixth embodiment of the present invention is described with reference to
Fig 1 . The sixth embodiment shown inFig. 1 differs from the first embodiment in that feed-water specific enthalpy increases in thesecond feed heaters 8 are calculated in consideration of a feed-water specific enthalpy increase by afeed pump 12. Other structures of the sixth embodiment are substantially the same as those of the first embodiment. - The
feed pump 12 increases a pressure of a feed water, and simultaneously heats the feed water, as described in the third embodiment, so that a specific enthalpy of the feed water is increased. In consideration of the specific enthalpy increase, an average specific enthalpy increase in each of thesecond feed heaters 8 is calculated. - This embodiment can be carried out, in the above-described fourth embodiment, by calculating specific enthalpy increases of feed waters in the
feed heaters feed pump 12. - Also in this case, since the
feed pump 12 increases a pressure of a feed water, and simultaneously heats the feed water, so that a specific enthalpy of the feed water is increased. Thus, in consideration of the specific enthalpy increase, an average specific enthalpy increase in each of thefeed heaters - A feed water temperature at an inlet of a
boiler 4 is generally defined by theboiler 4. Thus, with a feed-water temperature value being fixed, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5. - In addition to the reason as described in the first embodiment, a specific enthalpy increase ratio may vary within a certain range, under influences of a heat generation difference caused by a mechanical difference in the
feed pump 12. - As described above, by calculating a specific enthalpy increase in a feed water in consideration of a specific enthalpy increase in the feed water by the
feed pump 12, and then by determining a temperature increase ratio, a cycle thermal efficiency can be increased, similarly to the second and fourth embodiments. - Next, a seventh embodiment of the present invention is described with reference to
Fig 1 . - In the first embodiment, the third embodiment, and the fifth embodiment, the eight
feed heaters 6 in total are used and a cycle structure is made such that a temperature increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, the number of thefeed heaters 6 is preferably eight from an economical point of view. - In
Fig. 1 , steam is bled at two positions from theintermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from thelow pressure turbine 3. However, as long as the total number of the bleed positions is six, the number and the positions are not limited thereto. - In
Fig. 1 , a bleed steam to theaerator 9 is the intermediate-pressure turbineexhaust bleed steam 32, but is not limited thereto. With the number of thefeed heaters 6 being limited to eight, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5. - As described above, in the first embodiment, the third embodiment, and the fifth embodiment, by using eight
feed heaters 6 in total, and by making a cycle structure such that a temperature increase ratio falls within 1.9 - 3.5, a cycle thermal efficiency can be improved, similarly to the first embodiment, third embodiment, and the fifth embodiment. - Next, an eighth embodiment of the present invention is described with reference to
Fig 1 . - In the second embodiment, the fourth embodiment, and the sixth embodiment, the eight
feed heaters 6 in total are used and a cycle structure is made such that a specific enthalpy increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, the number of thefeed heaters 6 is preferably eight from an economical point of view. - In
Fig. 1 , steam is bled at two positions from theintermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from thelow pressure turbine 3. However, as long as the total number of the bleed positions is six, the number and the positions are not limited thereto. - In
Fig. 1 , a bleed steam to theaerator 9 is the intermediate-pressure turbineexhaust bleed steam 32, but is not limited thereto. With the number of thefeed heaters 6 being limited to eight, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5. - As described above, in the first embodiment, the third embodiment, and the fifth embodiment, by using eight
feed heaters 6 in total, and by making a cycle structure such that a specific enthalpy increase ratio falls within 1.9 - 3.5, a cycle thermal efficiency can be improved, similarly to the second embodiment, fourth embodiment, and the sixth embodiment. - Next, a ninth embodiment of the present invention is described with reference to
Fig 2 . InFig. 2 , the same parts as those ofFig. 1 are shown by the same reference numbers, and their detailed description is omitted. - In this embodiment, by adding one
feed heater 6 to the eightfeed heaters 6 in total as in the above first embodiment, the third embodiment, and the fifth embodiment, the ninefeed heaters 6 in total are used, and a cycle structure is made such that a temperature increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, although the number of thefeed heaters 6 is preferably eight from an economical point of view, there is a case in which the number of thefeed heaters 6 is preferably nine, with a view to more increasing an efficiency, an output, and a temperature of a main steam. - In
Fig. 2 , steam is bled at three positions from anintermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from alow pressure turbine 3. However, as long as the total number of the bleed positions is seven, the number and the positions are not limited thereto. - In
Fig. 2 , a bleed steam to adeaerator 9 is an intermediate pressureturbine exhaust steam 32, but is not limited thereto. With the number of thefeed heaters 6 being limited to nine, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a temperature increase ratio falls within 1.9 - 3.5. - As described above, in this embodiment, by using the nine
feed heaters 6 in total by adding onefeed heater 6 to the eightfeed heaters 6 in total as in the above first embodiment, the third embodiment, and the fifth embodiment, and by making a cycle structure such that a temperature increase ratio falls within 1.9 - 3.5, a cycle thermal efficiency can be improved, similarly to the first embodiment, the third embodiment, and the fifth embodiment. - Next, a tenth embodiment of the present invention is described with reference to
Fig. 2 . - In this embodiment, by adding one
feed heater 6 to the eightfeed heaters 6 in total as in the above second embodiment, the fourth embodiment, and the sixth embodiment, the ninefeed heaters 6 in total are used, and a cycle structure is made such that a specific enthalpy increase ratio falls within 1.9 - 3.5. This is because, in a large heat power plant, although the number of thefeed heaters 6 is preferably eight from an economical point of view, there is a case in which the number of thefeed heaters 6 is preferably nine, with a view to more increasing an efficiency, an output, and a temperature of a main steam. - In
Fig. 2 , steam is bled at three positions from anintermediate pressure turbine 2 including exhaust of steam, and steam is bled at four positions from alow pressure turbine 3. However, as long as the total number of the bleed positions is seven, the number and the positions are not limited thereto. - In
Fig. 2 , a bleed steam to adeaerator 9 is an intermediate pressureturbine exhaust steam 32, but is not limited thereto. With the number of thefeed heaters 6 being limited to nine, an optimization calculation was conducted. Then, it was found that a cycle thermal efficiency becomes maximum under conditions that a specific enthalpy increase ratio falls within 1.9 - 3.5. - As described above, in this embodiment, by using the nine
feed heaters 6 in total by adding onefeed heater 6 to the eightfeed heaters 6 in total as in the above second embodiment, the fourth embodiment, and the sixth embodiment, and by making a cycle structure such that a specific enthalpy increase ratio falls within 1.9 - 3.5, a cycle thermal efficiency can be improved, similarly to the second embodiment, the fourth embodiment, and the sixth embodiment. - Next, an eleventh embodiment of the present invention is described with reference to
Figs. 1 and2 . - In the first to tenth embodiments, a cycle structure is made such that a steam temperature at an outlet of the
boiler 4 is 600°C or more. This is because, when a temperature of themain steam 16 is 600°C or above, a more significant effect can be expected. Namely, an effect of improving a cycle thermal efficiency due to an increased temperature of themain steam 16 is not damaged by set conditions of ableed steam 20 but can be fully exerted. - In the first to tenth embodiments, by making a cycle structure such that a steam temperature at an outlet of the
boiler 4 is 600°C or more, a cycle thermal efficiency can be improved, similarly to the first to tenth embodiments.
Claims (11)
- A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
wherein a steam temperature at an outlet of the boiler is 590°C or more, and characterized in that
a temperature increase ratio between: a feed-water temperature increase in a first feed heater (7) corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in second feed heaters (8) where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5. - A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
wherein a steam temperature at an outlet of the boiler is 590°C or more, and and characterized in that
a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater (7) corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed waters in second feed heaters (8) where a pressure of the feed water is lower than that of the first feed heater; falls within 1.9 - 3.5. - A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
wherein a steam temperature at an outlet of the boiler is 590°C or more, and chararcterized in that
a temperature increase ratio between: a feed-water temperature increase in a first feed heater (7) corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of feed-water temperature increases in feed heaters (8, 26) other than the first feed heater; falls within 1.9 - 3.5. - A steam turbine cycle comprising a high pressure turbine, a reheating turbine, a boiler, feed heaters for heating a feed water to the boiler by a bleed steam from the high pressure turbine and the reheating turbine, a feed pump, and a condenser, the steam turbine cycle being a single-stage reheating cycle where a working fluid is water and using a Rankine cycle which is a regenerative cycle,
wherein a steam temperature at an outlet of the boiler is 590°C or more, and characterized in that
a specific enthalpy increase ratio between: a specific enthalpy increase in a feed water in a first feed heater (7) corresponding to a bleed steam from an exhaust steam of the high pressure turbine; and an average of specific enthalpy increases in feed heaters (8, 26) other than the first feed heater; falls within 1.9 - 3.5. - The steam turbine cycle according to claim 1 or 3, wherein
the feed-water temperature increases in the second feed heaters are calculated, in consideration of a temperature increase in the feed water by the feed pump. - The steam turbine cycle according to claim 2 or 4, wherein
the specific enthalpy increases in feed waters in the second feed heaters are calculated, in consideration of a specific enthalpy increase in the feed water by the feed pump. - The steam turbine cycle according to one of claims 1, 3, and 5, wherein
the total number of the feed heaters is eight, and
the temperature increase ratio falls within 1.9 - 3.5. - The steam turbine cycle according to one of claims 2, 4, and 6, wherein
the total number of the feed heaters is eight, and
the specific enthalpy increase ratio falls within 1.9 - 3.5. - The steam turbine cycle according to one of claims 1, 3, and 5, wherein
the total number of the feed heaters is nine, and
the temperature increase ratio falls within 1.9 - 3.5. - The steam turbine cycle according to one of claims 2, 4, and 6, wherein
the total number of the feed heaters is nine, and
the specific enthalpy increase ratio falls within 1.9 - 3.5. - The steam turbine cycle according to one of claims 1 to 10, wherein
a steam temperature at an outlet of the boiler is 600°C or above.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006012124A JP4621597B2 (en) | 2006-01-20 | 2006-01-20 | Steam turbine cycle |
PCT/JP2006/325524 WO2007083478A1 (en) | 2006-01-20 | 2006-12-21 | Steam turbine cycle |
Publications (3)
Publication Number | Publication Date |
---|---|
EP1965043A1 EP1965043A1 (en) | 2008-09-03 |
EP1965043A4 EP1965043A4 (en) | 2014-07-02 |
EP1965043B1 true EP1965043B1 (en) | 2016-03-09 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP06843008.1A Expired - Fee Related EP1965043B1 (en) | 2006-01-20 | 2006-12-21 | Steam turbine cycle |
Country Status (6)
Country | Link |
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US (1) | US20090094983A1 (en) |
EP (1) | EP1965043B1 (en) |
JP (1) | JP4621597B2 (en) |
KR (1) | KR20080038233A (en) |
CN (1) | CN101300407B (en) |
WO (1) | WO2007083478A1 (en) |
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WO2008119784A2 (en) * | 2007-03-30 | 2008-10-09 | Siemens Aktiengesellschaft | Arrangement with a steam turbine and a condenser |
US8443606B2 (en) | 2008-03-26 | 2013-05-21 | Babcock & Wilcox Power Generation Group, Inc. | Enhanced steam cycle utilizing a dual pressure recovery boiler with reheat |
EP2204553A1 (en) | 2008-06-23 | 2010-07-07 | Siemens Aktiengesellschaft | Steam power assembly |
EP2333256B1 (en) * | 2009-12-08 | 2013-10-16 | Alstom Technology Ltd | Power plant with CO2 capture and method to operate such power plant |
US8596034B2 (en) | 2010-03-31 | 2013-12-03 | Eif Nte Hybrid Intellectual Property Holding Company, Llc | Hybrid power generation cycle systems and methods |
US8161724B2 (en) * | 2010-03-31 | 2012-04-24 | Eif Nte Hybrid Intellectual Property Holding Company, Llc | Hybrid biomass process with reheat cycle |
US8418467B2 (en) * | 2010-06-29 | 2013-04-16 | General Electric Company | System including feedwater heater for extracting heat from low pressure steam turbine |
JP5912323B2 (en) * | 2010-10-19 | 2016-04-27 | 株式会社東芝 | Steam turbine plant |
JP5818557B2 (en) | 2010-10-19 | 2015-11-18 | 株式会社東芝 | Steam turbine plant |
JP5672450B2 (en) * | 2011-02-25 | 2015-02-18 | 株式会社ササクラ | Fresh water generator and fresh water generation method |
US8495878B1 (en) | 2012-04-09 | 2013-07-30 | Eif Nte Hybrid Intellectual Property Holding Company, Llc | Feedwater heating hybrid power generation |
CN103696816B (en) * | 2013-12-15 | 2016-05-25 | 河南省电力勘测设计院 | A kind of resuperheat low capacity split shaft Turbo-generator Set |
RU2560510C1 (en) * | 2014-03-11 | 2015-08-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Operating method of thermal power plant |
RU2560607C1 (en) * | 2014-04-07 | 2015-08-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Heat power plant operation mode |
RU2562724C1 (en) * | 2014-05-06 | 2015-09-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Utilisation method of thermal energy generated by thermal power plant |
RU2562730C1 (en) * | 2014-05-06 | 2015-09-10 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Казанский государственный энергетический университет" (ФГБОУ ВПО "КГЭУ") | Utilisation method of thermal energy generated by thermal power plant |
CN104358596B (en) * | 2014-10-31 | 2016-05-18 | 中国大唐集团科学技术研究院有限公司 | Many steam turbines cogeneration ultra supercritical unit |
CN110206601A (en) * | 2019-06-04 | 2019-09-06 | 大唐郓城发电有限公司 | A kind of steam turbine air inlet protective device |
CN111946412A (en) * | 2020-07-06 | 2020-11-17 | 东方电气集团东方汽轮机有限公司 | Back pressure type steam turbine system with heat regeneration system |
CN112780373B (en) * | 2020-12-30 | 2022-11-11 | 华北电力大学(保定) | Water vapor cycle based on supercritical and subcritical heat regeneration |
CN113137289A (en) * | 2021-05-28 | 2021-07-20 | 西安热工研究院有限公司 | Double-machine heat regeneration-based double reheating 650 ℃ ultra-supercritical coal-fired power generation system |
CN113137290A (en) * | 2021-05-28 | 2021-07-20 | 西安热工研究院有限公司 | High-parameter steam turbine steam reheating circulating system |
CN113898429B (en) * | 2021-11-09 | 2023-07-21 | 华北电力大学(保定) | Supercritical reheat regenerative Rankine cycle system |
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JPS5438710B2 (en) * | 1973-06-15 | 1979-11-22 | ||
US4314442A (en) * | 1978-10-26 | 1982-02-09 | Rice Ivan G | Steam-cooled blading with steam thermal barrier for reheat gas turbine combined with steam turbine |
JPS61205309A (en) * | 1985-03-08 | 1986-09-11 | Hitachi Ltd | Protective operating method and its device of feed water heater |
JPH04298604A (en) * | 1990-11-20 | 1992-10-22 | General Electric Co <Ge> | Combined cycle power plant and steam supply method |
JP3315800B2 (en) * | 1994-02-22 | 2002-08-19 | 株式会社日立製作所 | Steam turbine power plant and steam turbine |
US5836162A (en) * | 1996-08-08 | 1998-11-17 | Power Software Associates, Inc. | Feedwater heater drain recycle system |
US7028479B2 (en) * | 2000-05-31 | 2006-04-18 | Siemens Aktiengesellschaft | Method and device for operating a steam turbine comprising several no-load or light-load phases |
-
2006
- 2006-01-20 JP JP2006012124A patent/JP4621597B2/en not_active Expired - Fee Related
- 2006-12-21 KR KR1020087006641A patent/KR20080038233A/en not_active Application Discontinuation
- 2006-12-21 US US12/092,796 patent/US20090094983A1/en not_active Abandoned
- 2006-12-21 CN CN2006800405919A patent/CN101300407B/en not_active Expired - Fee Related
- 2006-12-21 WO PCT/JP2006/325524 patent/WO2007083478A1/en active Application Filing
- 2006-12-21 EP EP06843008.1A patent/EP1965043B1/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
CN101300407A (en) | 2008-11-05 |
JP2007192152A (en) | 2007-08-02 |
CN101300407B (en) | 2011-01-19 |
US20090094983A1 (en) | 2009-04-16 |
JP4621597B2 (en) | 2011-01-26 |
KR20080038233A (en) | 2008-05-02 |
EP1965043A4 (en) | 2014-07-02 |
EP1965043A1 (en) | 2008-09-03 |
WO2007083478A1 (en) | 2007-07-26 |
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