CN114876597B - System and method for realizing island operation of thermal power generating unit by coupling molten salt energy storage - Google Patents
System and method for realizing island operation of thermal power generating unit by coupling molten salt energy storage Download PDFInfo
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- CN114876597B CN114876597B CN202210545716.4A CN202210545716A CN114876597B CN 114876597 B CN114876597 B CN 114876597B CN 202210545716 A CN202210545716 A CN 202210545716A CN 114876597 B CN114876597 B CN 114876597B
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- 238000004146 energy storage Methods 0.000 title claims abstract description 83
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- 230000008878 coupling Effects 0.000 title claims abstract description 18
- 238000010168 coupling process Methods 0.000 title claims abstract description 18
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 18
- 238000010248 power generation Methods 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000003303 reheating Methods 0.000 claims abstract description 14
- 238000012360 testing method Methods 0.000 claims abstract description 4
- 238000000605 extraction Methods 0.000 claims description 46
- 230000001105 regulatory effect Effects 0.000 claims description 39
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- 238000010521 absorption reaction Methods 0.000 claims description 15
- 238000009833 condensation Methods 0.000 claims description 15
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- 238000010276 construction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
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- 230000002159 abnormal effect Effects 0.000 description 1
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- 238000006243 chemical reaction Methods 0.000 description 1
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- 238000013461 design Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005338 heat storage Methods 0.000 description 1
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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
- 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
- F01K13/00—General layout or general methods of operation of complete plants
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
- F22B1/028—Steam generation using heat accumulators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B1/00—Methods of steam generation characterised by form of heating method
- F22B1/02—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers
- F22B1/06—Methods of steam generation characterised by form of heating method by exploitation of the heat content of hot heat carriers the heat carrier being molten; Use of molten metal, e.g. zinc, as heat transfer medium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/0034—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D20/00—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
- F28D20/0034—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material
- F28D2020/0047—Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00 using liquid heat storage material using molten salts or liquid metals
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/14—Thermal energy storage
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Abstract
The invention discloses a method and a system for realizing island operation of a thermal power generating unit by coupling molten salt energy storage, wherein after FCB (fluid control bus) triggering, a turbine unit is switched from a power control mode to a rotating speed control mode, and a turbine is switched from a combined steam inlet mode to a medium-pressure cylinder steam inlet mode; after the rotation speed of the unit is stable, steam can be provided through the fused salt energy storage module, and the island operation of the steam turbine is maintained; after the FCB acts, closing a pipeline from the molten salt energy storage module to the deaerator, and communicating the pipeline from the molten salt energy storage module to the condenser; high-temperature steam is released to the molten salt energy storage module through the high-pressure bypass pipeline and the reheating cold section pipeline; stopping conveying reheat heat section steam, medium pressure cylinder steam exhaust and boiler water supply to the molten salt energy storage module after delay delta t seconds; delta t is confirmed according to the thermal inertia and test results of different units; the multi-path steam sources are reasonably distributed, the steam distribution mode of the thermal power generation system and the fused salt energy storage module is optimized, and the fused salt energy storage module is fully utilized to reduce the heat loss of steam in the FCB action process on the basis of realizing the island operation function.
Description
Technical Field
The invention relates to molten salt energy storage, in particular to a system and a method for realizing island operation of a thermal power unit by coupling molten salt energy storage.
Background
In recent years, a part of regional output strong local power grid planning construction implementation scheme requires to select a batch of power supply guarantee points as important load centers, and the power supply guarantee capability under an extreme state is improved in a key way, so that the island operation function is realized. According to the conventional solution thought, FCB (Fast Cut Back) functional transformation is mainly performed on a thermodynamic system equipment side (such as a bypass system, a steam source switching system, a PCV valve and the like) and an automatic control system so as to realize island operation of the thermal power unit. Due to sudden faults, the unit immediately loses all loads, the FCB is rapidly controlled at the moment that the unit is suspended at the edge of the full stop, and all automatic control systems of the machine, the furnace and the electricity need to make accurate coordination reaction to the control mode and the process regulation in a very short time, so that the functional reliability of the FCB cannot be completely ensured. In addition, the fused salt energy storage (heat storage) technology is widely applied to coupling with thermal power units, and has huge market space in the aspects of realizing deep peak regulation, frequency modulation, construction of a Kano battery energy storage power station and application of retired unit transformation of the units.
The energy storage scheme of the FCB reconstruction of the existing unit mostly adopts battery energy storage, and is mainly limited by the safety problem and high cost that the battery energy storage cannot be ignored, so that the FCB reconstruction is difficult to popularize. The existing scheme for solving island operation by adopting molten salt energy storage is mainly researched in aspects of electric connection mode and steam distribution of molten salt and thermodynamic system. The operation method of an energy storage module, the control mode of a steam turbine and how a steam source is kept in a hot standby state in the energy storage and release stage of a thermal power generating unit with coupled molten salt energy storage when the transient switching of the FCB occurs are not fully considered.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a system and a method for realizing island operation of a thermal power unit by coupling molten salt energy storage, which fully consider the operation method of an energy storage module, the control mode of a steam turbine and the method for keeping a hot standby state of a steam source in the energy storage and release stages of the thermal power unit by coupling molten salt energy storage when the transient switching of the FCB occurs.
The invention is realized by the following technical scheme: in the method, after FCB triggering, a turbine set is switched from a power control mode to a rotating speed control mode, and a turbine is switched from a combined steam inlet mode to a medium-pressure cylinder steam inlet mode; after the rotation speed of the unit is stable, steam can be provided through the fused salt energy storage module, and the island operation of the steam turbine is maintained;
after the FCB acts, the pipeline from the molten salt energy storage module to the deaerator is automatically closed, and the pipeline from the molten salt energy storage module to the condenser is opened in a chained manner; the molten salt energy storage module recovers heat of main steam entering the reheat cold section pipeline through the high-pressure bypass; stopping conveying the reheat heat section steam, the medium-pressure cylinder steam exhaust and boiler water supply to the fused salt energy storage module after triggering the FCB and delaying for deltat seconds; delta t is confirmed according to the thermal inertia and FCB dynamic test results of different units.
The method for storing the steam in the normal operation stage comprises the following steps: the water supply is provided from the final-stage high-water-adding side to the fused salt energy storage module, the water supply absorbs heat in the fused salt system and becomes superheated steam, the generated superheated steam is finally sent to a steam supply main pipe of the fused salt energy storage module, and the pressure is gradually increased to meet the set value p of the steam inlet parameter of the medium-pressure cylinder under the FCB working condition set 。
The condensation preventing method for the steam supply main pipe of the molten salt energy storage module comprises the following steps: when the pressure p of the steam supply main pipe of the fused salt energy storage module A Is lower than a set value p of a steam supply main pipe of the fused salt energy storage module set When the condensation preventing regulating valve is kept unchanged, the lowest opening is kept to be 5%;
when the pressure p of the steam supply main pipe A Is higher than the set value p of the steam supply main pipe set When the condensation-preventing regulating valve is put into operation automatically, the pressure value of the steam supply main pipe is regulated to p set 。
When the temperature before the steam trap is lower than p A And when the temperature is saturated, the condensation alarm device gives out audible and visual alarm.
The molten salt heating at the operation stage comprises the following steps: after the fused salt energy storage module exchanges heat with the extraction steam of the existing thermal power generation system, the temperature is raised by an electric heater to store heat in fused salt, the fused salt energy storage module enters a deaerator under normal working conditions after the extraction steam is released, and the FCB enters a condenser under working conditions.
The invention also provides a system for realizing island operation of the thermal power generating unit by coupling molten salt energy storage, which comprises the existing thermal power generation system, a steam extraction main pipe, a steam supply main pipe and a molten salt energy storage module; the steam extraction main pipe is connected with a heat absorption loop of the molten salt energy storage module, and the heat absorption loop is also connected with a condenser and a deaerator of the thermal power generation system; the superheated steam outlet of the molten salt energy storage module is sequentially connected with a steam supply main pipe and a middle pressure cylinder inlet of a steam turbine of the existing thermal power generation system, a final-stage high-pressure heater of the existing thermal power generation system is connected with a heat release loop of the molten salt energy storage module, a valve rear pipeline of a high-pressure bypass valve in the existing thermal power generation system is connected with a steam extraction main pipe, and a valve front pipeline of a middle pressure cylinder steam discharge valve is connected with the steam extraction main pipe; the reheating heat section steam pipeline is also connected with a heat absorption loop of the fused salt energy storage module.
The molten salt energy storage module comprises a low-temperature molten salt storage tank and a high-temperature molten salt storage tank, a pipeline from the low-temperature molten salt storage tank to the high-temperature molten salt storage tank is a heat absorption loop, a low-temperature molten salt pump, a first molten salt heat exchanger, a second molten salt heat exchanger and an electric heater are sequentially arranged in the heat absorption loop along the molten salt flow direction, the pipeline from the high-temperature molten salt storage tank to the low-temperature molten salt storage tank is an exothermic loop, and a high-temperature molten salt pump, a third molten salt heat exchanger and a fourth molten salt heat exchanger are sequentially arranged in the exothermic loop along the molten salt flow direction.
The outlet of the steam extraction main pipe is connected with the hot side inlet of the first molten salt heat exchanger, and the hot side outlet of the first molten salt heat exchanger is connected with the condenser or the deaerator; the hot side outlet of the first molten salt heat exchanger, the condenser and the deaerator are provided with shut-off valves, and the shut-off valves are controlled in a linkage manner; the reheating heat section steam pipeline is connected with a hot side inlet of the second molten salt heat exchanger, a hot side outlet of the second molten salt heat exchanger is connected with a steam extraction main pipe inlet, and a check valve and a pneumatic regulating valve are sequentially arranged from the reheating heat section steam pipeline to the hot side inlet of the second molten salt heat exchanger.
The cold side inlet of the fourth molten salt heat exchanger is connected with the outlet of the last-stage high-pressure heater, the cold side outlet of the third molten salt heat exchanger is connected with a steam supply main pipe, and a check valve and a steam extraction regulating valve are sequentially arranged on a pipeline from the steam supply main pipe to the inlet of the middle pressure cylinder of the steam turbine.
The steam supply main pipe is also connected with a hot side inlet of the second molten salt heat exchanger, and a pneumatic regulating valve and a check valve are sequentially arranged from the steam supply main pipe to the hot side inlet of the second molten salt heat exchanger; and a steam trap is arranged on a pipeline from the steam supply main pipe to the middle pressure cylinder of the steam turbine and used for preventing condensation and ensuring that the steam supply main pipe is always in a hot standby state.
A heating regulating valve is arranged between a valve front pipeline of the medium pressure cylinder exhaust valve and the steam extraction main pipe.
Compared with the prior art, the invention has the following beneficial technical effects:
according to the method, the steam distribution mode of the thermal power generation system and the fused salt energy storage module is optimized, and the fused salt energy storage module is fully utilized to reduce the heat loss of steam in the FCB action process on the basis of realizing the island operation function; the reasonable distribution of the multiple paths of steam sources can reduce the equipment transformation cost, and the mixed steam sources with different differences are sent to the heat exchange equipment to improve the heat exchange efficiency; the operation method of the energy storage module when the FCB working condition transient switching occurs in the unit is provided, and beneficial references are provided for follow-up unit transformation, system optimization, control mode optimization and the like.
Furthermore, the condensation prevention measures of the main steam supply pipe are fully considered, a hot standby steam source can be provided for a long period in all weather, and the reliability of the island operation of the unit is improved.
According to the system, the steam supply main pipe and the steam extraction main pipe are arranged between the molten salt energy storage module and the existing thermal power generation system, so that the multi-path steam sources are reasonably distributed, the equipment transformation cost can be reduced, the steam sources with different differences are mixed and then sent into the heat exchange equipment, different steam sources can be reasonably applied, and the heat exchange efficiency is improved.
Drawings
Fig. 1 is a system diagram for realizing island operation of a thermal power generating unit by coupling molten salt energy storage.
In the figure: 1-boiler, 2-turbine high pressure cylinder, 3-turbine intermediate pressure cylinder, 4-turbine low pressure cylinder, 5-generator, 6-condenser, 7-deaerator, 8-feed pump, 9-final stage high pressure heater, 10-low temperature molten salt storage tank, 11-high temperature molten salt storage tank, 12, 16-molten salt pump, 13-first molten salt heat exchanger, 14-second molten salt heat exchanger, 15-electric heater, 17-third molten salt heat exchanger, 18-fourth molten salt heat exchanger, 19-steam trap, 30-high pressure bypass valve, 31-first check valve, 32-second check valve, 35-third check valve, 37-fourth check valve, 40-fifth check valve, 33-cold section to extraction main regulating valve, 34-feed regulating valve, 36-steam supply regulating valve, 38-extraction regulating valve, 39-condensation preventing regulating valve, 41-intermediate pressure cylinder exhaust valve, 42-heating regulating valve, 43-first control valve, 44-second control valve; a-steam supply main pipe and B-steam extraction main pipe
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the accompanying drawings. The figures are not drawn to scale, wherein certain details are exaggerated for clarity of presentation and may have been omitted. The shapes of the various regions, layers and their relative sizes, positional relationships shown in the drawings are merely exemplary, may in practice deviate due to manufacturing tolerances or technical limitations, and one skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions as actually required.
Referring to fig. 1, a system for realizing island operation functions of a thermal power generating unit by coupling molten salt energy storage comprises an existing thermal power generation system, a molten salt energy storage module and a steam extraction and supply pipeline, wherein the existing thermal power generation system comprises a typical boiler 1, a turbine high-pressure cylinder 2, a turbine medium-pressure cylinder 3, a turbine low-pressure cylinder 4, a generator 5, a condenser 6, a deaerator 7, a water supply pump 8, a multi-stage high-pressure heater, a high-pressure bypass valve 30 and a medium-pressure cylinder steam discharge valve 41; the boiler 1, the high-pressure cylinder 2 of the steam turbine, the medium-pressure cylinder 3 of the steam turbine, the low-pressure cylinder 4 of the steam turbine, the generator 5, the condenser 6, the deaerator 7, the water supply pump 8 and the multistage high-pressure heater are sequentially connected, wherein the final-stage heater 9 in the multistage high-pressure heater is connected with the water supply inlet of the boiler 1, and the molten salt energy storage module comprises a high-temperature molten salt storage tank 11, a low-temperature molten salt storage tank 10, a high-temperature molten salt pump 16, a low-temperature molten salt pump 12, a molten salt heat exchanger, an electric heater 15 and the like; the molten salt heat exchanger comprises a third molten salt heat exchanger 17 and a fourth molten salt heat exchanger which are arranged on a path from the high-temperature molten salt storage tank 11 to the low-temperature molten salt storage tank 10, wherein the third molten salt heat exchanger 17 and the fourth molten salt heat exchanger are connected in series, and a first molten salt heat exchanger 13 and a second molten salt heat exchanger 14 which are arranged on a path from the low-temperature molten salt storage tank 10 to the high-temperature molten salt storage tank 11 are connected in series, the first molten salt heat exchanger 13 and the second molten salt heat exchanger 14 are connected in series, and the steam extraction and steam supply pipeline system comprises a steam supply main pipe A, a steam extraction main pipe B, a steam supply regulating valve 36, a condensation prevention regulating valve 39, a steam extraction regulating valve 38, a steam trap 19, a check valve and the like.
The steam extraction main pipe is connected with a heat absorption loop of the molten salt energy storage module, and the heat absorption loop is also connected with a condenser 6 and a deaerator 7 of the thermal power generation system; the superheated steam outlet of the molten salt energy storage module is sequentially connected with a steam supply main pipe and a middle pressure cylinder inlet of a steam turbine of the existing thermal power generation system, a final-stage high-pressure heater 9 of the existing thermal power generation system is connected with a heat release loop of the molten salt energy storage module, a valve rear pipeline of a high-pressure bypass valve 30 in the existing thermal power generation system is connected with a steam extraction main pipe, and a valve front pipeline of a middle pressure cylinder steam discharge valve 41 is connected with the steam extraction main pipe; the reheating heat section steam pipeline is also connected with a heat absorption loop of the fused salt energy storage module.
The molten salt energy storage module comprises a low-temperature molten salt storage tank 10 and a high-temperature molten salt storage tank 11, wherein a pipeline from the low-temperature molten salt storage tank 10 to the high-temperature molten salt storage tank 11 is a heat absorption loop, a low-temperature molten salt pump 12, a first molten salt heat exchanger 13, a second molten salt heat exchanger 14 and an electric heater 15 are sequentially arranged in the heat absorption loop along the molten salt flow direction, a pipeline from the high-temperature molten salt storage tank 11 to the low-temperature molten salt storage tank 10 is a heat release loop, and a high-temperature molten salt pump 16, a third molten salt heat exchanger 17 and a fourth molten salt heat exchanger 18 are sequentially arranged in the heat release loop along the molten salt flow direction; the outlet of the steam extraction main pipe is connected with the hot side inlet of the first molten salt heat exchanger 13, and the hot side outlet of the first molten salt heat exchanger 13 is connected with the condenser 6 and/or the deaerator 7; regulating valves are arranged from the hot side outlet of the first molten salt heat exchanger 13 to the condenser 6 and the deaerator 7, and the regulating valves are controlled in a linkage manner; the reheating heat section steam pipeline is connected with a hot side inlet of the second molten salt heat exchanger 14, a hot side outlet of the second molten salt heat exchanger 14 is connected with a steam extraction main pipe inlet, and a check valve and a pneumatic regulating valve are sequentially arranged from the reheating heat section steam pipeline to the hot side inlet of the second molten salt heat exchanger 14; the cold side inlet of the fourth molten salt heat exchanger 18 is connected with the outlet of the last-stage high-pressure heater 9, the cold side outlet of the third molten salt heat exchanger 17 is connected with a steam supply main pipe, and a check valve and an electric regulating valve are sequentially arranged on a pipeline from the steam supply main pipe to the inlet of the middle pressure cylinder 3 of the steam turbine.
The steam supply main pipe is also connected with the hot side inlet of the second molten salt heat exchanger 14, the pneumatic regulating valve and the check valve are sequentially arranged from the steam supply main pipe to the hot side inlet of the second molten salt heat exchanger 14, and the steam trap 19 is arranged on the pipeline from the steam supply main pipe to the middle pressure cylinder 3 of the steam turbine.
A pipeline behind a high-pressure bypass valve 30 (namely a reheating cold section pipeline) in the existing thermal power generation system is led out of one path of steam, and the steam is sent into a steam extraction main pipe after passing through a second check valve 32 and a cold section to a steam extraction main pipe regulating valve 33; one path of steam is led out from the front of a medium pressure cylinder steam exhaust valve 41 of the medium pressure cylinder steam exhaust pipeline and is sent into a steam extraction main pipe; the steam of the reheating heat section of the extraction part enters the second fused salt heat exchanger 14 through the fourth check valve 37 and the steam extraction regulating valve 38, and the steam after heat exchange is discharged to a steam extraction main pipe.
Three streams of steam entering the steam extraction main pipe are mixed and then sent to the first molten salt heat exchanger 13 to release heat, the low-grade steam after heat release is discharged to the deaerator 7 under normal working conditions, and when the deaerator 7 generates abnormal working conditions such as water level abnormality or pressure limitation, the low-grade steam is discharged to the condenser 6.
The water fed from the outlet of the last-stage high-pressure heater 9 enters a fourth molten salt heat exchanger 18 and a third molten salt heat exchanger 17 in sequence to absorb heat, and after absorbing heat, the water becomes high-grade steam which enters a steam supply main pipe; after FCB occurs, steam in the steam supply main pipe is sent to the inlet of the middle pressure cylinder 3 of the steam turbine through the third check valve 35 and the steam supply regulating valve 36, so that the stable operation of the steam turbine unit 3000r/min with the load of the plant is maintained, and the stable island operation is realized.
In order to ensure that the steam of the steam supply main pipe is always in a hot standby condition, a stream of steam is led out from the bottom of the tail end of the steam supply main pipe, is connected with the steam from the hot re-pipeline through a condensation prevention regulating valve 39 and a fifth check valve 40, and enters the steam side of the second molten salt heater 14 after being mixed; meanwhile, a steam trap is arranged on the steam inlet side of the intermediate pressure cylinder, which is close to the steam inlet side of the intermediate pressure cylinder, of the steam supply main pipe and the hot re-pipeline, and condensed water is timely thinned.
An operation method for realizing island operation of a thermal power generating unit by coupling molten salt energy storage comprises the following steps:
the method for storing the steam in the normal operation stage comprises the following steps:
extracting part of high-temperature feed water from a water side outlet of the final-stage high-pressure heater 9, sending the extracted part of high-temperature feed water into a fourth molten salt heat exchanger 18 to absorb heat to generate saturated steam, sending the generated saturated steam into the third molten salt heat exchanger 17 again to absorb heat to generate superheated steam, and finally sending the generated superheated steam to a steam supply main pipe, and gradually boosting the pressure to ensure that parameters of the steam supply main pipe meet a set value p of steam inlet parameters of a medium-pressure cylinder under FCB working conditions set 。
The condensation prevention method of the steam supply main pipe comprises the following steps:
when the pressure p of the steam supply main pipe A Is lower than the set value p of the steam supply main pipe set When the condensation preventing regulating valve is kept unchanged, the lowest opening is kept to be 5%;
when the pressure p of the steam supply main pipe A Is higher than the set value p of the steam supply main pipe set When the condensation-preventing regulating valve is put into operation automatically, the pressure value of the steam supply main pipe is regulated to p set ；
When the temperature before the steam trap is lower than p A And when the temperature is saturated, the condensation alarm device gives out audible and visual alarm.
The molten salt heating method in the operation stage comprises the following steps:
starting a low-temperature molten salt pump 12, establishing molten salt working medium circulation, and enabling molten salt from the low-temperature molten salt storage tank 10 to enter a first molten salt heat exchanger 13 to exchange heat with steam from the steam extraction main pipe B. And the released steam enters the deaerator 8 under the normal working condition, and when the water level of the deaerator 8 exceeds an alarm value or the pressure of the deaerator exceeds the alarm value, the steam is blocked to enter the deaerator, and at the moment, the valve of the condenser is opened in a linkage way.
The molten salt working medium entering the second molten salt heat exchanger 14 exchanges heat with the extracted hot steam, the steam after heat release enters the steam extraction main pipe B, the absorbed molten salt enters the molten salt electric heater 15 for temperature rising again, and finally the molten salt rising to the set temperature enters the high-temperature molten salt tank.
The FCB working condition triggering operation method comprises the following steps:
after FCB acts, the pneumatic valve 44 from the first molten salt heat exchanger 13 to the deaerator 7 is closed in a linkage manner, and the pneumatic valve 43 from the first molten salt heat exchanger 13 to the condenser 43 is opened in a linkage manner;
after the FCB acts, automatically opening a reheating cold section pipeline to a cold section of the steam extraction main pipe B and a steam extraction main pipe regulating valve 33, and rapidly releasing high-temperature steam entering the cold re-pipeline through a high side;
after FCB acts, the following valves are closed in a linkage way after the delay of deltat seconds, wherein the valves comprise a steam extraction regulating valve 38 from a reheating heat section to the second molten salt heater 14, a heating regulating valve 42 from a medium-pressure cylinder steam exhaust pipeline to a steam extraction main pipe B, and a water supply regulating valve 34 from an outlet of a final-stage high-pressure heater 9 to a fourth molten salt heater 18, and deltat is confirmed according to the thermal inertia and test results of different units.
After FCB acts, the turbine unit is switched from a power control mode to a rotating speed control mode, the turbine is switched from a combined steam inlet mode to a medium-pressure cylinder steam inlet mode, and the rotating speed of the unit is quickly stabilized; after the rotation speed of the unit is stable, steam can be provided through the steam supply main pipe, and the island operation of the steam turbine is maintained.
The above is only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (7)
1. A method for realizing island operation of a thermal power generating unit by coupling molten salt energy storage is characterized in that after FCB triggering, a turbine unit is switched from a power control mode to a rotating speed control mode, and a turbine is switched from a combined steam inlet mode to a medium-pressure cylinder steam inlet mode; after the rotation speed of the unit is stable, steam can be provided through the fused salt energy storage module, and the island operation of the steam turbine is maintained;
after the FCB acts, the pipeline from the molten salt energy storage module to the deaerator (7) is automatically closed, and the pipeline from the molten salt energy storage module to the condenser (6) is opened in a chained manner; the molten salt energy storage module recovers heat of main steam entering the reheat cold section pipeline through the high-pressure bypass; stopping conveying the reheat heat section steam, the medium-pressure cylinder steam exhaust and boiler water supply to the fused salt energy storage module after triggering the FCB and delaying for deltat seconds; delta t is confirmed according to the thermal inertia and FCB dynamic test results of different units; the condensation preventing method for the steam supply main pipe of the molten salt energy storage module comprises the following steps: when the pressure p of the steam supply main pipe of the fused salt energy storage module A Is lower than a set value p of a steam supply main pipe of the fused salt energy storage module set When the condensation preventing regulating valve is kept unchanged, the lowest opening is kept to be 5%;
when the pressure p of the steam supply main pipe A Is higher than the set value p of the steam supply main pipe set When the condensation-preventing regulating valve is put into operation automatically, the pressure value of the steam supply main pipe is regulated to p set ；
When the temperature before the steam trap is lower than p A And when the temperature is saturated, the condensation alarm device gives out audible and visual alarm.
2. The method for realizing island operation of a thermal power generating unit by coupling molten salt energy storage according to claim 1, wherein the method for storing steam in a normal operation stage is as follows: the water supply is provided from the final-stage high-water-adding side to the fused salt energy storage module, the water supply absorbs heat in the fused salt system and becomes superheated steam, the generated superheated steam is finally sent to a steam supply main pipe of the fused salt energy storage module, and the pressure is gradually increased to meet the set value p of the steam inlet parameter of the medium-pressure cylinder under the FCB working condition set 。
3. The method for realizing island operation of a thermal power generating unit by coupling molten salt energy storage according to claim 1, wherein the molten salt heating at the operation stage is specifically: after the fused salt energy storage module exchanges heat with the extraction steam of the existing thermal power generation system, the temperature is raised by an electric heater to store heat in fused salt, the fused salt energy storage module enters a deaerator under normal working conditions after the extraction steam is released, and the FCB enters a condenser under working conditions.
4. The island operation system for the thermal power generating unit realized by coupling molten salt energy storage is characterized by comprising an existing thermal power generation system, a steam extraction main pipe, a steam supply main pipe and a molten salt energy storage module, wherein the method is used for realizing any one of claims 1-3; the steam extraction main pipe is connected with a heat absorption loop of the molten salt energy storage module, and the heat absorption loop is also connected with a condenser (6) and a deaerator (7) of the thermal power generation system; the superheated steam outlet of the molten salt energy storage module is sequentially connected with a steam supply main pipe and a middle pressure cylinder inlet of a steam turbine of the existing thermal power generation system, a final-stage high-pressure heater (9) of the existing thermal power generation system is connected with a heat release loop of the molten salt energy storage module, a valve rear pipeline of a high-pressure bypass valve (30) in the existing thermal power generation system is connected with a steam extraction main pipe, and a valve front pipeline of a middle pressure cylinder steam discharge valve (41) is connected with the steam extraction main pipe; the reheating heat section steam pipeline is also connected with a heat absorption loop of a molten salt energy storage module, the molten salt energy storage module comprises a low-temperature molten salt storage tank (10) and a high-temperature molten salt storage tank (11), a pipeline from the low-temperature molten salt storage tank (10) to the high-temperature molten salt storage tank (11) is a heat absorption loop, a low-temperature molten salt pump (12), a first molten salt heat exchanger (13), a second molten salt heat exchanger (14) and an electric heater (15) are sequentially arranged in the heat absorption loop along the molten salt flow direction, a pipeline from the high-temperature molten salt storage tank (11) to the low-temperature molten salt storage tank (10) is a heat release loop, and a high-temperature molten salt pump (16), a third molten salt heat exchanger (17) and a fourth molten salt heat exchanger (18) are sequentially arranged in the heat release loop along the molten salt flow direction; the outlet of the steam extraction main pipe is connected with the hot side inlet of the first molten salt heat exchanger (13), and the hot side outlet of the first molten salt heat exchanger (13) is connected with the condenser (6) or the deaerator (7); the hot side outlet of the first molten salt heat exchanger (13) is provided with a shutoff valve to the condenser (6) and the deaerator (7), and the shutoff valves are controlled in a interlocking way; the reheating heat section steam pipeline is connected with a hot side inlet of the second molten salt heat exchanger (14), a hot side outlet of the second molten salt heat exchanger (14) is connected with a steam extraction main pipe inlet, and a check valve and a pneumatic regulating valve are sequentially arranged from the reheating heat section steam pipeline to the hot side inlet of the second molten salt heat exchanger (14).
5. The island operation system for the thermal power generating unit realized by coupling molten salt energy storage according to claim 4 is characterized in that a cold side inlet of a fourth molten salt heat exchanger (18) is connected with an outlet of a final-stage high-pressure heater (9), a cold side outlet of a third molten salt heat exchanger (17) is connected with a steam supply main pipe, and a check valve and a steam extraction regulating valve are sequentially arranged on a pipeline from the steam supply main pipe to an inlet of a middle pressure cylinder (3) of a steam turbine.
6. The island operation system of the thermal power generating unit realized by coupling molten salt energy storage according to claim 4, wherein the steam supply main pipe is also connected with a hot side inlet of the second molten salt heat exchanger (14), and a pneumatic regulating valve and a check valve are sequentially arranged from the steam supply main pipe to the hot side inlet of the second molten salt heat exchanger (14); and a steam trap (19) is arranged on a pipeline from the steam supply main pipe to the middle pressure cylinder (3) of the steam turbine and used for preventing condensation and ensuring that the steam supply main pipe is always in a hot standby state.
7. The island operation system of the thermal power generating unit realized by coupling molten salt energy storage according to claim 4, wherein a heating regulating valve is arranged between a valve front pipeline of a medium pressure cylinder steam exhaust valve (41) and a steam extraction main pipe.
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