CN113932213A - Steam system of power generation steam turbine unit and coal-fired power generator unit - Google Patents
Steam system of power generation steam turbine unit and coal-fired power generator unit Download PDFInfo
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- CN113932213A CN113932213A CN202010676415.6A CN202010676415A CN113932213A CN 113932213 A CN113932213 A CN 113932213A CN 202010676415 A CN202010676415 A CN 202010676415A CN 113932213 A CN113932213 A CN 113932213A
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- 238000010248 power generation Methods 0.000 title claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 239
- 238000000605 extraction Methods 0.000 claims abstract description 89
- 238000010438 heat treatment Methods 0.000 claims abstract description 15
- 238000013021 overheating Methods 0.000 abstract description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 9
- 239000001301 oxygen Substances 0.000 description 9
- 229910052760 oxygen Inorganic materials 0.000 description 9
- 238000010586 diagram Methods 0.000 description 5
- 230000001172 regenerating effect Effects 0.000 description 4
- 239000003245 coal Substances 0.000 description 2
- 238000009833 condensation Methods 0.000 description 2
- 230000005494 condensation Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/50—Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
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- 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
- F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
- F01D15/10—Adaptations for driving, or combinations with, electric generators
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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
- F01K11/00—Plants characterised by the engines being structurally combined with boilers or condensers
- F01K11/02—Plants characterised by the engines being structurally combined with boilers or condensers the engines being turbines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
- F22D1/32—Feed-water heaters, i.e. economisers or like preheaters arranged to be heated by steam, e.g. bled from turbines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
- F22D5/00—Controlling water feed or water level; Automatic water feeding or water-level regulators
- F22D5/26—Automatic feed-control systems
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- General Engineering & Computer Science (AREA)
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- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
The invention relates to the technical field of steam turbines, and discloses a steam system of a power generation steam turbine set and a coal-fired generator set, wherein the system comprises: the system comprises a boiler, a steam turbine, a condenser, a plurality of low-pressure condensed water heaters, a deaerator, a plurality of high-pressure feed water heaters, a plurality of low-pressure steam extraction pipelines, a deaerator steam extraction pipeline and a plurality of high-pressure steam extraction pipelines, wherein the boiler, the steam turbine, the condenser, the plurality of low-pressure condensed water heaters, the deaerator and the plurality of high-pressure feed water heaters are sequentially communicated; and the heat exchanger is arranged on the deoxidizing and steam extracting pipeline and/or the plurality of low-pressure steam extracting pipelines and is also communicated with a high-pressure feed water outlet of the deaerator and the boiler for heating part of high-pressure feed water flowing out of the deaerator by using extracted steam from the steam turbine so as to supply the boiler. The heat exchanger is arranged, so that the heat of the steam overheating part in the corresponding pipeline can be recycled, and the heat efficiency and the power generation output power of the steam-water circulating system are improved.
Description
Technical Field
The invention relates to the technical field of steam turbines, in particular to a steam-water system of a power generation steam turbine unit and a coal-fired generator unit.
Background
The steam-water system of the steam turbine generator set based on the Rankine cycle is composed of a boiler, a steam turbine, a condenser, a deaerator, a feed water heater and other equipment and connecting pipelines. As shown in figure 1, high-temperature and high-pressure steam generated by a boiler 1 enters high-pressure, medium-pressure and low-pressure turbines (2, 3 and 4) along a steam pipeline to do work, the steam is discharged into a condenser 6 to be cooled into condensed water, the condensed water is pressurized and conveyed to a low-pressure condensed water heater series (8-11) by a condensed water pump 7 and is heated step by utilizing partial extracted steam from the low-pressure turbine 4, then enters a deaerator 12, is heated by partial extraction steam from the medium pressure turbine 3, is pressurized by a water feeding pressurizing pump 13, enters a high pressure feed water heater series (14-16), and is heated step by step to the feed water temperature required by the boiler by partial extraction steam from the high and medium pressure turbines (2, 3), then returning to the boiler 1 to regenerate steam to drive the steam turbine to drive the generator 5 to generate power and output, and repeating the steps in such a way, but the comprehensive thermal efficiency of the steam-water circulating system is low.
CN102720550A discloses a dual-turbine regenerative steam extraction thermodynamic system, in which a high-pressure steam extraction port is arranged at the middle stage of a high-pressure cylinder of a main turbine, the high-pressure steam extraction port is connected with a steam inlet of a small turbine and a high-pressure heater with the highest steam inlet parameter among a plurality of high-pressure heaters through a high-pressure steam extraction pipeline, a plurality of regenerative steam extraction ports are arranged at the middle stage of the small turbine, the plurality of regenerative steam extraction ports are connected with the other high-pressure heaters except the high-pressure heater with the highest steam inlet parameter through regenerative steam extraction pipelines, and a steam outlet of the small turbine is connected with a deaerator through a small turbine steam exhaust pipeline. The system can save a high-temperature preposed steam cooler, reduce the feed water temperature of the boiler, is beneficial to improving the boiler efficiency and reducing the heat consumption of a unit, but has complex system and high investment, operation and maintenance cost.
US3291105A discloses a technique for extracting steam and cooling a deaerator by using low-pressure condensate water, which is mainly used for regulation and control under emergency conditions and does not have the purpose and effect of improving the thermal efficiency of a steam-water circulation system.
Therefore, there is a need for a new steam-water system for a power generating steam turbine set.
Disclosure of Invention
The invention aims to solve the problem of low heat efficiency of the existing steam-water circulating system, and provides a steam system of a power generation steam turbine unit and a coal-fired power generator unit.
In order to achieve the above object, a first aspect of the present invention provides a steam-water system for a power generating turbine unit, including: the system comprises a boiler, a steam turbine, a condenser, a plurality of low-pressure condensed water heaters, a deaerator, a plurality of high-pressure feed water heaters, a plurality of low-pressure steam extraction pipelines, a deaerator steam extraction pipeline and a plurality of high-pressure steam extraction pipelines, wherein the boiler, the steam turbine, the condenser, the plurality of low-pressure condensed water heaters, the deaerator and the plurality of high-pressure feed water heaters are sequentially communicated; and the heat exchangers are respectively arranged on the deoxidizing steam extraction pipeline and/or the low-pressure steam extraction pipelines and are also communicated with a high-pressure water supply outlet of the deaerator and the boiler, and the heat exchangers are used for heating part of high-pressure water supply flowing out of the deaerator by using extraction steam from the steam turbine to supply the boiler.
In a second aspect, the invention provides a coal-fired power generating unit comprising the steam-water system of the power generating steam turbine set of the first aspect.
Through the technical scheme, the heat exchangers are respectively arranged on the deoxidizing steam extraction pipeline and/or the plurality of low-pressure steam extraction pipelines, so that part of high-pressure feed water absorbs heat of a steam overheating part in the deoxidizing steam extraction pipeline and/or the low-pressure steam extraction pipelines through the heat exchangers, and the part of high-pressure feed water is heated to be supplied to a boiler.
Drawings
FIG. 1 is a schematic diagram of a steam-water system of a typical steam turbine-generator set;
FIG. 2 is a schematic diagram of a steam-water system of a power generating steam turbine set according to a preferred embodiment of the present invention;
FIG. 3 is a schematic diagram of a steam-water system of a power generating steam turbine set according to another preferred embodiment of the present invention.
Description of the reference numerals
1 boiler 2 high pressure turbine 3 medium pressure turbine
4 low pressure turbine 5 generator 6 condenser
7 condensate pump 8 primary low-pressure condensate water heater 9 secondary low-pressure condensate water heater
10 three-stage low-pressure condensed water heater 11 final-stage low-pressure condensed water heater 12 deaerator
13 water supply pressure pump 14 primary high pressure feed water heater 15 secondary high pressure feed water heater
16 final stage high pressure feed water heater 17 first heat exchanger 18 second heat exchanger
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
At present, the heat sources for the low-pressure condensate heaters, deaerators and high-pressure feedwater heaters of each stage are generally derived from a portion of the steam (called extraction) that has been used to perform work in some intermediate stages of the turbine. In principle, latent heat released by the condensation of extracted steam is mainly used for heating water, so that the steam temperature of the heated water approaches to the saturation temperature under corresponding pressure. However, the steam extraction for each stage of water heater has a certain superheat degree relative to the outlet water temperature of the heater, so that the part of heat of the superheat section of the steam extraction of the steam turbine, which is higher than the saturation temperature, is used for water heating, and the heat is high in quality and low in use. In order to solve the problems, the inventor of the present invention researches and discovers that the heat of the steam superheating part can be recycled by arranging a heat exchanger on a steam extraction pipeline, so as to improve the thermal efficiency of the system, and further, for example, a typical 320MW subcritical condensation gas generator set, the steam extraction for heating the deaerator is about 7.6bar of superheated steam at 325 ℃, which is much higher than the saturation temperature 168 ℃ required by the deaerator for heating; the steam for heating the final-stage low-pressure condensed water heater is 222 ℃ superheated steam of about 3bar, which is far higher than the outlet water temperature 131 ℃ of the final-stage low-pressure condensed water heater, and the extracted steam for the deaerator and the final-stage low-pressure condensed water heater has relatively larger superheated temperature, so that the heat of the superheated parts can be further improved by arranging the heat exchangers on the steam extraction pipelines of the deaerator and the final-stage low-pressure condensed water heater and upgrading the heat of the superheated parts.
As previously mentioned, a first aspect of the present invention provides a steam-water system for a power generating turboset, comprising: the system comprises a boiler, a steam turbine, a condenser, a plurality of low-pressure condensed water heaters, a deaerator, a plurality of high-pressure feed water heaters, a plurality of low-pressure steam extraction pipelines, a deaerator steam extraction pipeline and a plurality of high-pressure steam extraction pipelines, wherein the boiler, the steam turbine, the condenser, the plurality of low-pressure condensed water heaters, the deaerator and the plurality of high-pressure feed water heaters are sequentially communicated; and the heat exchangers are respectively arranged on the deoxidizing steam extraction pipeline and/or the low-pressure steam extraction pipelines and are also communicated with a high-pressure water supply outlet of the deaerator and the boiler, and the heat exchangers are used for heating part of high-pressure water supply flowing out of the deaerator by using extraction steam from the steam turbine to supply the boiler.
In some embodiments of the present invention, preferably, the system further comprises a condensate pump and a feed water pressurizing pump, wherein the condensate pump is arranged between the condenser and the primary low-pressure condensate heater and is used for pumping the condensate into the low-pressure condensate heater for heating; the water supply pressurizing pump is arranged between the deaerator and the primary high-pressure water supply heater and is used for pressurizing the condensed water deaerated by the deaerator to enable the condensed water to enter the high-pressure water supply heater for continuous high-pressure heating. The high-pressure feed water is obtained by pressurizing the condensed water after being deoxidized by the deaerator by the feed water pressurizing pump, namely the feed water at the outlet of the feed water pressurizing pump.
In some embodiments of the present invention, there is no particular limitation on the type of the steam turbine as long as it can output high pressure extraction steam, intermediate pressure extraction steam, and low pressure extraction steam. For example, the steam turbine may be an integrated steam turbine including a high-pressure cylinder, an intermediate-pressure cylinder and a low-pressure cylinder, or may be a separated high-pressure steam turbine, an intermediate-pressure steam turbine and a low-pressure steam turbine, and the high-pressure cylinder or the high-pressure steam turbine is respectively communicated with the plurality of high-pressure feed water heaters through a plurality of high-pressure steam extraction pipelines; the intermediate pressure cylinder or the intermediate pressure turbine is respectively communicated with the deaerator and part of the high pressure feed water heater through a deaerating steam extraction pipeline and part of the high pressure steam extraction pipeline; and the low-pressure cylinder or the low-pressure turbine is respectively communicated with the low-pressure condensed water heaters through a plurality of low-pressure steam extraction pipelines.
In some embodiments of the present invention, the heat exchanger is not particularly limited, and may be a vapor-liquid (e.g., steam-water) indirect heat exchanger known in the art, such as, but not limited to, a shell-tube type heat exchanger.
The deaerator of the invention is used for heating boiler feed water to saturation temperature corresponding to the operating pressure of the deaerator by using steam extraction of a steam turbine, removing oxygen and other non-condensable gases dissolved in the water, improving the quality of the boiler feed water, and preventing or reducing oxygen corrosion of the boiler, the steam turbine and auxiliary equipment, pipelines and the like.
The low-pressure condensed water heater utilizes partial extraction steam from a low-pressure turbine to heat condensed water flowing out of a condenser to a temperature required by entering a deaerator. The high pressure feedwater heater heats high pressure feedwater to a feedwater temperature required by the boiler using a portion of the extraction steam from the high pressure turbine or the intermediate pressure turbine.
In some embodiments of the present invention, it is preferable that the pressure of the high-pressure feed water is higher than the pressure of the deaerator and/or the low-pressure condensed water heater from the steam turbine extraction steam, and the temperature of the high-pressure feed water is lower than the temperature of the deaerator and/or the low-pressure condensed water heater from the steam turbine extraction steam, so that the heat of the superheated part in the extraction steam with relatively low-pressure and high-temperature (i.e. the heat of the saturated steam temperature section with the temperature higher than the extraction steam pressure) can be used for heating the water in the deaerator and/or the low-pressure condensed water heater, and can be used for heating the feed water of the boiler with higher pressure, so that the heat of the superheated part of the low-pressure extraction steam can be used in an upgrading way. Meanwhile, a part of the feed water at the outlet of the feed water pressurizing pump is shunted and enters the heat exchanger for heating, so that the water flow entering the high-pressure feed water heater is correspondingly reduced, and the requirement of the high-pressure feed water heater on the high-pressure extraction steam volume of the steam turbine is also reduced, thereby increasing the power generation output power of the steam turbine and improving the comprehensive thermal efficiency of a steam-water circulating system.
In some embodiments of the present invention, the heat exchanger may be disposed on the oxygen removal extraction duct and/or on the plurality of low pressure extraction ducts for recycling heat of the superheated steam portion in the oxygen removal extraction duct and/or in the plurality of low pressure extraction ducts, i.e., the heat exchanger may be disposed on the oxygen removal extraction duct only, or on the plurality of low pressure extraction ducts only, or on both the oxygen removal extraction duct and the plurality of low pressure extraction ducts, preferably, the heat exchanger is disposed on the oxygen removal extraction duct and/or on the last low pressure extraction duct in the plurality of low pressure extraction ducts, respectively.
In some embodiments of the present invention, the amount of the high-pressure feed water flowing into the heat exchanger is not particularly limited, and the amount of the inflow water is based on the feed water temperature required by the boiler inlet under the corresponding working condition, that is, as long as the return water temperature reached after the high-pressure feed water flowing into the heat exchanger passes through the heat exchanger meets the water temperature of the boiler water, preferably, the temperature of the outlet return water of the heat exchanger is the same as the feed water temperature of the boiler economizer inlet under the corresponding load. According to the invention, the flow control valve is arranged on the communication pipeline between the outlet of the feed water pressurizing pump and the inlet of the heat exchanger, so that the flow of high-pressure feed water flowing into the heat exchanger can be adjusted, and the return water temperature at the outlet of the heat exchanger is controlled to be the same as the feed water temperature at the inlet of the boiler economizer under corresponding load.
In some embodiments of the invention, the high-pressure feed water flowing out of the outlet of the heat exchanger can be returned to any position in the feed water heating system connecting pipeline downstream of the outlet of the feed water pressurizing pump in principle, and preferably, the return water point of the outlet return water of the heat exchanger is arranged on the connecting pipeline between the high-pressure feed water outlet of the deaerator and the inlet of the boiler economizer. Further preferably, a backwater point of the outlet backwater of the heat exchanger is arranged on an outlet of the final-stage high-pressure feed water heater, an inlet of the boiler economizer or a connecting pipeline between the outlet of the final-stage high-pressure feed water heater and the inlet of the boiler economizer, so that the heated high-pressure feed water can be returned to the boiler for reuse more easily.
In a second aspect, the invention provides a coal-fired power generating unit comprising the steam-water system of the power generating steam turbine set of the first aspect.
The invention will be described in detail below by means of two preferred embodiments.
A preferred embodiment, as shown in fig. 2, is a schematic diagram of a typical steam-water system for a power generating steam turbine, comprising: the low-pressure steam turbine comprises a boiler 1, a high-pressure steam turbine 2, a medium-pressure steam turbine 3, a low-pressure steam turbine 4, a condenser 6, a condensate pump 7, a primary low-pressure condensate water heater 8, a secondary low-pressure condensate water heater 9, a tertiary low-pressure condensate water heater 10, a final low-pressure condensate water heater 11, a deaerator 12, a feed water booster pump 13, a primary high-pressure feed water heater 14, a secondary high-pressure feed water heater 15, a final high-pressure feed water heater 16, a first heat exchanger 17 and a generator 5 communicated with the high-pressure steam turbine 2, the medium-pressure steam turbine 3 and the low-pressure steam turbine 4 which are communicated in sequence, wherein the low-pressure steam turbine 4 is communicated with the primary to final low-pressure condensate water heaters (8-11) through a primary to final low-pressure steam extraction pipeline, the medium-pressure steam turbine 3 is communicated with the deaerator 12 and the primary high-pressure feed water heater 14 through a deaerator steam extraction pipeline and a primary high-pressure steam extraction pipeline, the high-pressure turbine 2 is respectively communicated with a secondary high-pressure water supply heater 15 and a final high-pressure water supply heater 16 through a secondary high-pressure steam extraction pipeline and a final high-pressure steam extraction pipeline, and the first heat exchanger 17 is arranged on the deoxidization steam extraction pipeline; high-temperature and high-pressure steam generated by a boiler 1 enters high-pressure, medium-pressure and low-pressure turbines (2, 3 and 4) along a steam pipeline to do work, the generated steam is cooled into condensed water through a condenser 6, the condensed water is pressurized through a condensed water pump 7 and is sequentially conveyed into first-stage to last-stage low-pressure condensed water heaters (8-11), the first-stage to last-stage low-pressure condensed water heaters (8-11) heat the condensed water step by utilizing partial extracted steam from the low-pressure turbine 4, the heated condensed water enters a deaerator 12, the deaerator 12 further heats the condensed water and removes oxygen in the condensed water by utilizing partial extracted steam from the medium-pressure turbine 3, then the obtained condensed water is pressurized through a feed water pressure pump 13, and a part of high-pressure feed water flowing out of an outlet of the feed water pressure pump 13 enters first-stage to last-stage high-pressure feed water heaters (14-16), the first-stage to last-stage high-pressure feed water heaters (14-16) heat the high-pressure feed water stage by using partial extraction steam from the medium and high-pressure turbines (3, 2) to meet the water temperature of boiler water, and then flow out from the outlet of the last-stage high-pressure feed water heater (16); another part of the high-pressure feed water flowing out of the outlet of the feed water pressurizing pump 13 flows into the first heat exchanger 17 through the flow control valve and the inlet of the first heat exchanger 17, the first heat exchanger 17 heats the inflow part of the high-pressure feed water by using partial extraction steam from the medium-pressure turbine 3 so that the temperature of the return water at the outlet of the first heat exchanger 17 is the same as the feed water temperature at the inlet of the boiler economizer under the corresponding load, and the heated part of the high-pressure feed water flows out of the outlet of the first heat exchanger 17 and returns to the outlet of the final-stage high-pressure feed water heater 16, is mixed with the part of the high-pressure feed water flowing out of the outlet of the final-stage high-pressure feed water heater 16, then returns to the boiler 1 together, and the cycle is repeated.
Compared with a steam-water system of the power generation steam turbine set without the first heat exchanger 17, on the basis of maintaining the same full-load main steam parameter, the power generation output power of the steam-water system of the power generation steam turbine set is increased by about 0.3MWe, and meanwhile, the net heat consumption rate of the system is reduced by about 10kJ/kWh, which is equivalent to the reduction of the power generation coal consumption by about 0.3 g/kWh.
Another preferred embodiment is a schematic diagram of a typical steam-water system of a power generating steam turbine set as shown in fig. 3, the steam-water system of the power generating steam turbine set comprising: the low-pressure steam turbine comprises a boiler 1, a high-pressure steam turbine 2, a medium-pressure steam turbine 3, a low-pressure steam turbine 4, a condenser 6, a condensate pump 7, a first-stage low-pressure condensate water heater 8, a second-stage low-pressure condensate water heater 9, a third-stage low-pressure condensate water heater 10, a last-stage low-pressure condensate water heater 11, a deaerator 12, a feed water booster pump 13, a first-stage high-pressure feed water heater 14, a second-stage high-pressure feed water heater 15, a last-stage high-pressure feed water heater 16, a first heat exchanger 17, a second heat exchanger 18 and a generator 5 communicated with the high-pressure steam turbine 2, the medium-pressure steam turbine 3 and the low-pressure steam turbine 4 which are sequentially communicated, wherein the low-pressure steam turbine 4 is respectively communicated with the first-stage to last-stage low-pressure condensate water heaters (8-11) through a first-stage to last-stage low-pressure steam extraction pipeline, the medium-pressure steam turbine 3 is respectively communicated with the deaerator 12 and the first-stage high-pressure feed water heater 14 through a deaerator and a first-stage high-pressure steam extraction pipeline, the high-pressure turbine 2 is respectively communicated with a second-stage high-pressure water supply heater 15 and a last-stage high-pressure water supply heater 16 through a second-stage high-pressure steam extraction pipeline and a last-stage high-pressure steam extraction pipeline, the first heat exchanger 17 is arranged on the deoxidization steam extraction pipeline, and the second heat exchanger 18 is arranged on the last-stage low-pressure steam extraction pipeline; high-temperature and high-pressure steam generated by a boiler 1 enters high-pressure, medium-pressure and low-pressure turbines (2, 3 and 4) along a steam pipeline to do work, the generated steam is cooled into condensed water through a condenser 6, the condensed water is pressurized through a condensed water pump 7 and is sequentially conveyed into first-stage to last-stage low-pressure condensed water heaters (8-11), the first-stage to last-stage low-pressure condensed water heaters (8-11) heat the condensed water step by utilizing partial extracted steam from the low-pressure turbine 4, the heated condensed water enters a deaerator 12, the deaerator 12 further heats the condensed water and removes oxygen in the condensed water by utilizing partial extracted steam from the medium-pressure turbine 3, then the obtained condensed water is pressurized through a feed water pressure pump 13, and a part of high-pressure feed water flowing out of an outlet of the feed water pressure pump 13 enters first-stage to last-stage high-pressure feed water heaters (14-16), the first-stage to last-stage high-pressure feed water heaters (14-16) heat the high-pressure feed water stage by using partial extraction steam from the medium and high-pressure turbines (3, 2) to meet the water temperature of boiler water, and then flow out from the outlet of the last-stage high-pressure feed water heater (16); the other part of the high-pressure feed water flowing out from the outlet of the feed water pressurizing pump 13 flows into a first heat exchanger 17 and a second heat exchanger 18 through a flow control valve, the inlet of the first heat exchanger 17 and the inlet of the second heat exchanger 18 respectively, the first heat exchanger 17 heats the inflow part of the high-pressure feed water by using partial extraction steam from the medium-pressure turbine 3 so that the temperature of the outlet return water of the first heat exchanger 17 is the same as the feed water temperature of the inlet of the boiler economizer under corresponding load, the second heat exchanger 18 heats the inflow part of the high-pressure feed water by using partial extraction steam from the low-pressure turbine 4 so that the temperature of the outlet return water of the second heat exchanger 18 is the same as the feed water temperature of the inlet of the boiler economizer under corresponding load, and the heated part of the high-pressure feed water flows out of the outlets of the first heat exchanger 17 and the second heat exchanger 18 respectively and returns to the outlet of the final-stage high-pressure feed water heater 16, mixed with the high-pressure feedwater flowing from the outlet of the final stage high-pressure feedwater heater 16 and then returned together into the boiler 1, and so on.
Compared with a steam-water system of the power generation steam turbine unit without the first heat exchanger 17 and the second heat exchanger 18, on the basis of maintaining the same full-load main steam parameter, the power generation output power of the steam-water system of the power generation steam turbine unit is increased by about 0.45MWe, and meanwhile, the net heat consumption rate of the system is reduced by about 16kJ/kWh, which is equivalent to the reduction of the power generation coal consumption by about 0.5 g/kWh.
In addition, the first heat exchanger 17 and the second heat exchanger 18 according to the present invention are not limited to the above two arrangements, and may be used in combination with a feed water bypass of an existing high-pressure feed water heater or an existing superheater desuperheating water bypass to reduce the investment cost of an additional pipeline. The invention can be used for the design of a newly-built generator set and can also be used for carrying out technical transformation on the existing generator set.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A power generating steam turbine plant steam-water system comprising: the system comprises a boiler, a steam turbine, a condenser, a plurality of low-pressure condensed water heaters, a deaerator, a plurality of high-pressure feed water heaters, a plurality of low-pressure steam extraction pipelines, a deaerator steam extraction pipeline and a plurality of high-pressure steam extraction pipelines, wherein the boiler, the steam turbine, the condenser, the plurality of low-pressure condensed water heaters, the deaerator and the plurality of high-pressure feed water heaters are sequentially communicated; the boiler is characterized in that heat exchangers are respectively arranged on the deoxidizing and steam extracting pipelines and/or the low-pressure steam extracting pipelines, and the heat exchangers are further communicated with a high-pressure feed water outlet of the deaerator and the boiler and used for heating part of high-pressure feed water flowing out of the deaerator by using extracted steam from the steam turbine to supply the boiler.
2. The system of claim 1, wherein the high pressure feed water has a pressure higher than a pressure of the deaerator and/or low pressure condensate heater from a turbine extraction, and the high pressure feed water has a temperature lower than a temperature of the deaerator and/or low pressure condensate heater from the turbine extraction.
3. A system according to claim 1 or 2, wherein a heat exchanger is provided on the oxygen-removing extraction duct and/or on a last low-pressure extraction duct of the plurality of low-pressure extraction ducts, respectively.
4. A system according to claim 3, wherein a heat exchanger is provided on the oxygen-scavenging extraction line.
5. The system of claim 4, wherein the high pressure feed water flowing into the heat exchanger reaches a return water temperature after passing through the heat exchanger that satisfies a water temperature of the boiler water;
preferably, the temperature of the outlet backwater of the heat exchanger is the same as the feed water temperature of the inlet of the boiler economizer under the corresponding load.
6. The system of claim 4 or 5, wherein a water return point of the outlet water return of the heat exchanger is arranged on a connecting pipeline between a high-pressure feed water outlet of the deaerator and an inlet of a boiler economizer;
preferably, the backwater point of the outlet backwater of the heat exchanger is arranged on the outlet of the last-stage high-pressure feed water heater, the inlet of the boiler economizer or a connecting pipeline between the outlet of the last-stage high-pressure feed water heater and the inlet of the boiler economizer.
7. A system according to claim 3 wherein a first heat exchanger is provided on the oxygen-scavenging extraction conduit and a second heat exchanger is provided on the final low pressure extraction conduit.
8. The system of claim 7, wherein the return water temperature reached by the high-pressure feed water flowing into the first heat exchanger or the second heat exchanger, respectively, after passing through the first heat exchanger or the second heat exchanger, meets the water temperature of the boiler water;
preferably, the temperature of the outlet backwater of the first heat exchanger or the second heat exchanger is the same as the feed water temperature of the inlet of the boiler economizer under the corresponding load.
9. The system of claim 7 or 8, wherein a water return point of outlet water return of the first heat exchanger or the second heat exchanger is arranged on a connecting pipeline between a high-pressure feed water outlet of the deaerator and an inlet of a boiler economizer;
preferably, a water return point of the outlet water return of the first heat exchanger or the second heat exchanger is arranged on an outlet of the last-stage high-pressure feed water heater, an inlet of the boiler economizer or a connecting pipeline between the outlet of the last-stage high-pressure feed water heater and the inlet of the boiler economizer.
10. A coal-fired power generation unit comprising the power generating turboset steam-water system of any one of claims 1 to 9.
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