CN115111016A - Industrial steam supply system and method capable of improving flexibility of coal-fired unit - Google Patents
Industrial steam supply system and method capable of improving flexibility of coal-fired unit Download PDFInfo
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- CN115111016A CN115111016A CN202210840143.8A CN202210840143A CN115111016A CN 115111016 A CN115111016 A CN 115111016A CN 202210840143 A CN202210840143 A CN 202210840143A CN 115111016 A CN115111016 A CN 115111016A
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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
- F01K17/00—Using steam or condensate extracted or exhausted from steam engine plant
- F01K17/02—Using steam or condensate extracted or exhausted from steam engine plant for heating purposes, e.g. industrial, domestic
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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
- 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
- F01K27/00—Plants for converting heat or fluid energy into mechanical energy, not otherwise provided for
- F01K27/02—Plants modified to use their waste heat, other than that of exhaust, e.g. engine-friction heat
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Abstract
The application discloses an industrial steam supply system and method capable of improving flexibility of a coal-fired unit, and the industrial steam supply system comprises a main steam pipeline, wherein partial main steam on the main steam pipeline flows into a high-side pipeline, a small backpressure machine and a generator are arranged on the high-side pipeline, the generator is driven by the small backpressure machine through the main steam to generate electricity and convey the electricity to an electricity utilization system, and the exhausted steam of the small backpressure machine enters a boiler reheater; the steam discharged by the boiler reheater is divided into a first pipeline and a reheat steam extraction pipeline, the reheat steam extraction pipeline is divided into a second pipeline and a third pipeline, the steam in the first pipeline is conveyed to the condenser, the steam in the second pipeline is conveyed to the heat exchanger to exchange heat with demineralized water and then enters the condenser, and the steam in the third pipeline is conveyed to the heat supply steam header to supply heat to the outside; the method and the device can greatly improve the flexibility of the coal-fired unit, enhance the steam supply capacity of the steam turbine in low-load industry and achieve the purpose of thermoelectric decoupling.
Description
Technical Field
The application belongs to the technical field of thermal power generation energy conservation, and particularly relates to an industrial steam supply system and method capable of improving flexibility of a coal-fired unit.
Background
The national policy encourages the existing coal-fired generating set to replace heat supply, actively shuts down the heating and industrial steam supply small boiler, and carries out heat supply reconstruction on the straight condensing unit with heat supply conditions. Meanwhile, in order to promote the consumption of clean energy, the storage coal-fired unit should be changed to the greatest extent, the deep peak regulation capacity of the coal-fired unit is improved, and the minimum power generation output of the coal-fired unit is required to reach 35% of rated load by policy. And many power generation companies require that the minimum generated output of subordinate power generation enterprises is lower than 30% of rated load.
Power generation enterprises in southern areas of China do not need to supply heating loads in winter, but most of the power generation enterprises provide industrial steam for peripheral enterprises, and the heat supply of the power generation enterprises does not meet the heat supply requirement of a cogeneration unit, so the power generation enterprises are scheduled according to a straight condensing unit and must participate in deep peak regulation of a thermal power unit. For different industrial steam users, the required steam pressure parameters are different due to different processes. For a large thermal power generating unit, the most common industrial heat users use steam with the pressure of 1-1.5MPa and the temperature of 300-.
The method is limited by the requirement of deep peak regulation operation of the unit, and the requirement of the steam turbine during peak period of steam utilization is difficult to meet sometimes when the steam turbine is used for hot re-extraction during low-load operation. Meanwhile, when the unit operates in deep peak shaving, the boiler is limited by low-load stable combustion and the flue gas temperature at the denitration inlet is too low, so that the deep peak shaving capacity of the boiler is limited. These two problems result in the boiler evaporating capacity being greater than the demand of the turbine, and the turbine heat is then limited by the body structure and cannot be extracted.
Disclosure of Invention
In order to solve the above problems, embodiments of the present application provide an industrial steam supply system and method capable of improving flexibility of a coal-fired unit, which can greatly improve flexibility of the coal-fired unit, enhance low-load industrial steam supply capability of a steam turbine, and achieve a purpose of thermoelectric decoupling, and the technical scheme is as follows:
the application provides an industrial steam supply system capable of improving flexibility of a coal-fired unit, and the industrial steam supply system comprises a main steam pipeline, wherein part of main steam on the main steam pipeline flows into a high-side pipeline, a small backpressure machine and a generator are arranged on the high-side pipeline, the generator is driven by the small backpressure machine through the main steam to generate electricity and convey the electricity to an electricity utilization system, and the exhausted steam of the small backpressure machine enters a boiler reheater; boiler re-heater exhaust steam reposition of redundant personnel is first pipeline and reheat steam extraction pipeline, reheat steam extraction pipeline reposition of redundant personnel is second pipeline and third pipeline, steam in the first pipeline is carried to the condenser, steam in the second pipeline carries and reentries after heat exchanger and the demineralized water heat transfer the condenser, steam in the third pipeline is carried and is used for external heat supply to the heat supply steam header.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in one embodiment, a water supplement heater is arranged on the third pipeline, and steam in the third pipeline is directly conveyed to the heat supply steam header or conveyed to the heat supply steam header after heat exchange by the water supplement heater.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in one embodiment, a heat storage tank is arranged on the second pipeline, the heat storage tank is a cold-hot water separated heat storage tank, cold water in the heat storage tank comes from demineralized water, and the cold demineralized water in the heat storage tank is conveyed into the heat exchanger to exchange heat with steam in the second pipeline, is heated, and then returns to the heat storage tank to be stored in a hot water mode.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in one embodiment, the hot water in the heat storage tank is directly conveyed to the deaerator to be used as water for replenishing the deaerator, or the hot water in the heat storage tank is conveyed to the water replenishing heater to exchange heat with the steam in the third pipeline, and then enters the deaerator after being heated.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit, a high-side stop valve and a high-side temperature and pressure reducing valve are further arranged on the high-side pipeline, part of main steam on the main steam pipeline flows into the high-side pipeline through the high-side stop valve, and exhaust steam after the small back pressure machine applies work enters the boiler reheater through the high-side temperature and pressure reducing valve.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in one embodiment, a heat exchanger inlet stop valve and a heat exchanger outlet stop valve are respectively arranged at two ends of the heat exchanger on the second pipeline, and steam in the second pipeline enters the heat exchanger to release heat and reduce temperature through the heat exchanger inlet stop valve and the heat exchanger outlet stop valve and then enters the condenser.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit, according to an embodiment, part of steam discharged by the boiler reheater enters a low-side pipeline, a low-side stop valve a is arranged on the low-side pipeline, the steam passes through the low-side pipeline and then is divided into the first pipeline and a reheat steam extraction pipeline, the reheat steam extraction pipeline is divided into a second pipeline and a third pipeline, a low-side temperature and pressure reducing valve and a low-side stop valve B are arranged on the first pipeline, and the steam in the first pipeline is subjected to temperature and pressure reduction through the low-side temperature and pressure reducing valve and the low-side stop valve B and then enters the condenser; and a reheating steam extraction temperature-reducing and pressure-reducing valve is arranged on the third pipeline, and the steam in the third pipeline is directly fed into the heat supply steam header after being subjected to temperature reduction and pressure reduction through the reheating steam extraction temperature-reducing and pressure-reducing valve.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit, an inlet electric door and an outlet electric door of the water replenishing heater are respectively arranged at two ends of the water replenishing heater, and a bypass electric door of the water replenishing heater connected with the water replenishing heater in parallel is arranged at the downstream of the reheating steam-extraction temperature-reducing and pressure-reducing valve on the third pipeline.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in one embodiment, a water replenishing bypass inlet electric door is arranged on a pipeline connecting the heat storage tank and the water replenishing heater, a water replenishing main circuit electric door is arranged on a pipeline connecting the heat storage tank and the deaerator, and a water replenishing bypass outlet electric door is arranged on a pipeline connecting the water replenishing heater and the deaerator.
The second aspect of the present application provides an industrial steam supply method capable of improving flexibility of a coal-fired unit, which utilizes steam in a third pipeline to meet the steam demand of industrial heat users during a steam consumption peak period, and comprises the following steps: the method comprises the following steps: opening the high-side stop valve, controlling the steam flow in the high-side pipeline through the high-side temperature and pressure reducing valve, simultaneously applying work to the steam through the small back pressure machine, and enabling the exhausted steam after the work is applied by the small back pressure machine to enter the boiler reheater; step two: open low other stop valve A and reheat extraction pressure and temperature reducing valve, steam in the boiler reheater passes through reheat extraction pressure and temperature reducing valve adjusts and gets into after meeting user's demand pressure and temperature the third pipeline, steam in the third pipeline passes through moisturizing heater bypass electrically operated gate directly gets into the heat supply steam header, perhaps steam in the third pipeline passes through get into behind the moisturizing heater the heat supply steam header.
For example, in one embodiment, the industrial steam supply method capable of improving flexibility of a coal-fired unit, which utilizes steam in the third pipeline to meet the steam demand of industrial heat users during the steam peak period, includes the following steps: the method comprises the following steps: opening the high-side stop valve, controlling the steam flow in the high-side pipeline through the high-side temperature and pressure reducing valve, simultaneously applying work to the steam through the small back pressure machine, and enabling the exhausted steam after the work is applied by the small back pressure machine to enter the boiler reheater; step two: the low bypass stop valve A and the heat exchanger inlet stop valve are opened, steam in the boiler reheater enters the second pipeline, the steam in the second pipeline enters the heat exchanger, the heat exchanger is opened after releasing heat and cooling, the heat exchanger outlet stop valve enters the condenser, and desalted water in the heat exchanger is stored in the heat storage tank after being subjected to heat exchange and warming.
For example, in the industrial steam supply method capable of improving the flexibility of the coal-fired unit provided by one embodiment, when there is no reheat extraction in the second pipeline, the water supplement bypass inlet electric door and the water supplement bypass outlet electric door are closed, the water supplement bypass main pipeline electric door is opened, and hot water in the heat storage tank directly enters the deaerator to serve as a supplement water; when reheating steam extraction is carried out in the second pipeline, the water supplementing bypass inlet electric door and the water supplementing bypass outlet electric door are opened, the water supplementing bypass main circuit electric door is closed, and hot water in the heat storage tank enters the deaerator as water supplement after the temperature of the water supplementing heater is increased.
The industrial steam supply system and the method capable of improving the flexibility of the coal-fired unit have the beneficial effects that: according to the application, the small back-pressing machine is arranged on the high-side pipeline, the generated power of the small back-pressing machine is integrated into an auxiliary power system and is used by a high-power auxiliary machine in a power plant, so that high-quality steam can be used for doing work, energy loss caused by direct temperature and pressure reduction is avoided, and the heat economy of bypass heat supply is improved; part of steam at the outlet of the boiler reheater is divided into three paths for use, one path of steam is subjected to temperature and pressure reduction and then used for supplying heat to the outside through a heat supply steam header, the other path of steam enters a condenser, and the other path of steam is used for heating demineralized water through a heat exchanger and storing hot water through a heat storage tank, so that the purpose of energy storage is realized; the heat storage tank is arranged, so that part of redundant heat can be stored, the flexibility of boiler operation is improved, the boiler can operate at a higher load during deep peak shaving, various equipment transformation for achieving low-load operation is avoided, and the reliability and the safety of operation are improved. The hot water stored in the heat storage tank is heated by the water supplementing heater and then enters the deaerator as the water supplemented to the thermodynamic system, and can also directly enter the deaerator as the water supplemented to the system. Meanwhile, due to the heat exchange of the water replenishing heater, the using amount of the temperature-reducing water can be effectively reduced, the steam extraction amount of industrial steam supply is increased, the thermoelectric ratio of the coal-electric unit is further improved, and the heat economy of the unit is improved. The flexibility of coal-fired unit can be improved by a wide margin, the steam supply capacity of the low-load industry of the steam turbine is enhanced, the purpose of thermoelectric decoupling is achieved, and meanwhile the engineering transformation amount of the boiler for meeting the deep peak shaving operation can be reduced, so that the whole unit can better deal with the heat supply problem in the deep peak shaving period.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow diagram of an industrial steam supply system of the present application that can improve the flexibility of a coal burning unit.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
The application provides an industrial steam supply system capable of improving flexibility of a coal-fired unit, as shown in fig. 1, the industrial steam supply system comprises a main steam pipeline 1, part of main steam on the main steam pipeline 1 flows into a high-side pipeline 2, a small back pressure machine 5 and a generator 4 are arranged on the high-side pipeline 2, the small back pressure machine 5 drives the generator 4 to generate power through the main steam and conveys the power to an electric system, and the power is used by auxiliary equipment in a power plant; the exhaust steam of the small back pressure machine 5 enters a boiler reheater; boiler re-heater exhaust steam reposition of redundant personnel is first pipeline and reheat steam extraction pipeline 23, reheat steam extraction pipeline 23 reposition of redundant personnel is second pipeline and third pipeline, steam in the first pipeline is carried to the condenser, steam in the second pipeline is carried and is reentrant after heat exchanger 25 and the demineralized water heat transfer the condenser, steam in the third pipeline is carried and is used for external heat supply to the heat supply steam header.
As shown in fig. 1, another part of the main steam on the main steam pipeline 1 flows into the high-pressure cylinder 6, and enters the boiler reheater through the high-pressure cylinder steam exhaust pipeline 7 and the high-pressure exhaust check valve 8 on the high-pressure cylinder steam exhaust pipeline 7.
As shown in fig. 1, the high-temperature side desuperheating water is delivered to the high-temperature side desuperheating pressure reducing valve 9 through a high-temperature side desuperheating water pipeline 10 and a high-temperature side desuperheating water stop door 12 and a high-temperature side desuperheating water regulating door 11 which are sequentially arranged on the high-temperature side desuperheating water pipeline 10.
As shown in fig. 1, the steam discharged from the boiler reheater is also branched to a fourth line, which is a reheat steam line 13, and the steam in the reheat steam line 13 enters an intermediate pressure cylinder 17.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a make-up water heater 34 is disposed on the third pipeline, and steam in the third pipeline is directly conveyed to the heating steam header or is conveyed to the heating steam header after being subjected to heat exchange by the make-up water heater 34.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a heat storage tank 30 is provided on the second pipeline, the heat storage tank 30 is a hot and cold water separated heat storage tank, cold water in the heat storage tank 30 is desalted water, the cold desalted water in the heat storage tank 30 is delivered into the heat exchanger 25 through a cold water pipeline 28 and a water pump 29 provided on the cold water pipeline 28 to exchange heat with steam in the second pipeline, the temperature of the cold desalted water is raised, and the hot water is returned to the heat storage tank 30 through a hot water pipeline 27 to be stored in a hot water form.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit provided in an embodiment, as shown in fig. 1, the hot water in the heat storage tank 30 is directly delivered to a deaerator to be used as a water supplement for the deaerator, or the hot water in the heat storage tank 30 is delivered to the water supplement heater 34 to be heated by heat exchange with the steam in the third pipeline, and then enters the deaerator.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a high-side stop valve 3 and a high-side pressure and temperature reducing valve 9 are further disposed on the high-side pipeline 2, a part of main steam on the main steam pipeline flows into the high-side pipeline 2 through the high-side stop valve 3, and exhaust steam after the small back pressure machine 5 applies work enters the boiler reheater through the high-side pressure and temperature reducing valve 9.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a heat exchanger inlet stop valve 24 and a heat exchanger outlet stop valve 26 are respectively arranged at two ends of the heat exchanger 25 on the second pipeline, and steam in the second pipeline enters the heat exchanger 25 through the heat exchanger inlet stop valve 24 and the heat exchanger outlet stop valve 26 to release heat and reduce temperature, and then enters the condenser.
For example, in the industrial steam supply system capable of improving the flexibility of a coal-fired unit according to an embodiment, as shown in fig. 1, a part of steam discharged from the boiler reheater enters a low-side pipeline 14, a low-side stop valve a15 is disposed on the low-side pipeline 14, the steam passes through the low-side pipeline 14 and is divided into the first pipeline and a reheat extraction pipeline 23, the reheat extraction pipeline 23 is divided into the second pipeline and a third pipeline, a low-side pressure reducing valve 16 and a low-side stop valve B21 are disposed on the first pipeline, and the steam in the first pipeline is subjected to temperature and pressure reduction through the low-side pressure reducing valve 16 and the low-side stop valve B21 and then enters the condenser; and a reheating steam extraction temperature-reducing and pressure-reducing valve 22 is arranged on the third pipeline, and steam in the third pipeline is directly fed into the heat supply steam header after being subjected to temperature and pressure reduction through the reheating steam extraction temperature-reducing and pressure-reducing valve 22.
As shown in fig. 1, the low-side desuperheating water is delivered to the low-side desuperheating pressure reducing valve 16 through a low-side desuperheating water pipeline 20 and a low-side desuperheating water stop gate 19 and a low-side desuperheating water regulating gate 18 which are sequentially arranged on the low-side desuperheating water pipeline 20.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a water supplement heater inlet electric door 35 and a water supplement heater outlet electric door 36 are respectively provided at both ends of the water supplement heater 34, and a water supplement heater bypass electric door 37 connected in parallel with the water supplement heater 34 is provided downstream of the reheat extraction temperature and pressure reducing valve 22 on the third pipeline.
For example, in the industrial steam supply system capable of improving the flexibility of the coal-fired unit according to an embodiment, as shown in fig. 1, a water replenishing bypass inlet electric door 32 is disposed on a pipeline connecting the heat storage tank 30 and the water replenishing heater 34, a water replenishing main circuit electric door 31 is disposed on a pipeline connecting the heat storage tank 30 and the deaerator, and a water replenishing bypass outlet electric door 33 is disposed on a water replenishing pipeline 38 connecting the water replenishing heater 34 and the deaerator.
The method for operating the heat storage tank 30 includes: when general industry supplies vapour, the steam that heat supply steam header supplied out no longer retrieves, therefore thermodynamic system need supply the equivalent demineralized water in step, has reached the effect of working medium equilibrium.
(1) If the unit reheating steam extraction pipeline 23 has no steam extraction, the water supplementing bypass inlet electric door 32 and the water supplementing bypass outlet electric door 33 are closed, the water supplementing bypass main circuit electric door 31 is opened, and hot water in the heat storage tank 30 directly enters the deaerator to serve as water supplement; (2) if steam is extracted in the unit reheating steam extraction pipeline 23, the water supplementing bypass inlet electric door 32 and the water supplementing bypass outlet electric door 33 are opened at the moment, the water supplementing bypass main circuit electric door 31 is closed, and hot water in the heat storage tank 30 enters the deaerator to serve as water supplementing after the temperature of the hot water is increased through the water supplementing heater 34, so that the heat economy of the unit can be further improved.
The second aspect of the application provides an industrial steam supply method capable of improving flexibility of a coal-fired unit, industrial heat users can need a large amount of steam extraction to meet production requirements in a steam consumption peak period, reheating steam extraction is limited by unit loads and structural characteristics of a steam turbine, the situation that the steam consumption requirements cannot be met can occur, and at the moment, steam in a third pipeline is utilized to meet the steam consumption requirements of the industrial heat users in the steam consumption peak period, and the method comprises the following steps:
the method comprises the following steps: opening the high side stop valve 3, controlling the steam flow in the high side pipeline 2 through the high side temperature and pressure reducing valve 9, simultaneously enabling the steam to work through the small back pressure machine 5, and enabling the exhausted steam after the small back pressure machine 5 works to enter the boiler reheater;
step two: the low bypass stop valve A15 and the reheat steam extraction temperature-reducing and pressure-reducing valve 22 are opened, the steam in the boiler reheater enters the third pipeline after being adjusted to the pressure and the temperature meeting the user requirements through the reheat steam extraction temperature-reducing and pressure-reducing valve 22, the steam in the third pipeline directly enters the heat supply steam header through the water supplement heater bypass electric door 37, or the steam in the third pipeline enters the heat supply steam header after passing through the water supplement heater 34, and therefore the temperature-reducing water does not need to be added under the condition.
For example, in the industrial steam supply method capable of improving the flexibility of the coal-fired unit provided by one embodiment, as shown in fig. 1, generally, the evaporation capacity of the boiler corresponds to a certain turbine load, and when the unit is provided with industrial steam supply, the evaporation capacity of the boiler is higher than the turbine load. When the load of the steam turbine is scheduled by a power grid, the load needs to be maintained at a low load, and the boiler is limited by coal quality or denitration problems, and other problems cause that the load cannot be maintained at the evaporation capacity corresponding to the load of the steam turbine, at the moment, the heat and electricity decoupling can be realized through the heat storage tank 30 and the small back pressure machine 5, the redundant evaporation capacity of the boiler is recovered, and the thermoelectric decoupling is realized by utilizing the second pipeline and the heat storage tank 30, which comprises the following steps:
the method comprises the following steps: opening the high side stop valve 3, controlling the steam flow in the high side pipeline 2 through the high side temperature and pressure reducing valve 9, simultaneously enabling the steam to work through the small back pressure machine 5, and enabling the exhausted steam after the small back pressure machine 5 works to enter the boiler reheater;
step two: open low other stop valve A15 with heat exchanger entry stop valve 24, steam in the boiler reheater gets into the second pipeline, steam in the second pipeline gets into open after the heat exchanger 25 is exothermic the cooling heat exchanger export stop valve 26 gets into the condenser, store after the demineralized water heat transfer in the heat exchanger 25 heaies up in the heat storage tank 30.
For example, in the industrial steam supply method capable of improving the flexibility of the coal-fired unit provided in one embodiment, as shown in fig. 1, a method for improving the economy of water supplement by using hot water stored in the thermal storage tank 30 is further included, and the level of the hot water stored in the thermal storage tank 30 is high, so that a deaerator can be directly supplemented, and meanwhile, the hot water can also be used as temperature-reducing water for industrial steam supply. Since the moisturizing heater 34 is a surface heater, unlike the water spray desuperheating, the desuperheating thereof does not increase the amount of steam, and thus it can increase the amount of steam extraction compared to the water spray desuperheating, and therefore its economy will be better. When general industry supplies vapour, the steam that heat supply steam header supplied out no longer retrieves, therefore thermodynamic system need supply the equivalent demineralized water in step, has reached the effect of working medium equilibrium. When no reheat extraction steam exists in the second pipeline, the water supplementing bypass inlet electric door 32 and the water supplementing bypass outlet electric door 33 are closed, the water supplementing bypass main pipeline electric door 31 is opened, and hot water in the heat storage tank 30 directly enters the deaerator to serve as water supplementing; when the second pipeline is internally provided with reheating steam extraction, the water supplementing bypass inlet electric door 32 and the water supplementing bypass outlet electric door 33 are opened, the water supplementing bypass main circuit electric door 31 is closed, and hot water in the heat storage tank 30 enters the deaerator as water supplementing after the temperature of the water supplementing heater 34 is increased.
The application examples of the industrial steam supply system and the method capable of improving the flexibility of the coal-fired unit are as follows:
1. when the generating capacity of the unit is 20% of rated load and the minimum evaporation capacity of the boiler is 30% of rated load, 10% of redundant steam evaporated by the boiler enters the high-side pipeline 2 to drive the small back pressure machine 5 to generate power, the steam exhausted by the small back pressure machine 5 enters the boiler reheater, the redundant 10% of steam at the outlet of the boiler reheater is externally supplied with steam through the reheating steam extraction pipeline 23, the excessive part which can not be used by a hot user enters the heat exchanger 25 to heat the desalted water, and hot water is stored in the heat storage tank 30. If the excess 10% steam fails to meet the hot user demand, the extraction of steam at the boiler reheater outlet may be increased while the heat exchanger inlet cutoff valve 24 and the heat exchanger outlet cutoff valve 26 of the heat exchanger 25 are closed to take the heat exchanger 25 out of service.
2. When the generating capacity of the unit is 20% of rated load, the lowest evaporation capacity of the boiler can also maintain 20% of rated load, but the hot re-extraction capacity is insufficient, the evaporation capacity of the boiler can be increased, the hot re-extraction capacity is improved through the high bypass pipeline 2 and the low bypass pipeline 14, the generating capacity of the unit is not increased, and the purpose of meeting the demand of hot users is achieved.
Although embodiments of the present application have been disclosed for illustrative purposes, those skilled in the art will recognize that: various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims (12)
1. An industrial steam supply system capable of improving flexibility of a coal-fired unit, comprising:
the system comprises a main steam pipeline, a high-side pipeline, a small backpressure machine and a power generation system, wherein part of main steam on the main steam pipeline flows into the high-side pipeline;
boiler re-heater exhaust steam reposition of redundant personnel is first pipeline and reheat steam extraction pipeline, reheat steam extraction pipeline reposition of redundant personnel is second pipeline and third pipeline, steam in the first pipeline is carried to the condenser, steam in the second pipeline carries and reentries after heat exchanger and the demineralized water heat transfer the condenser, steam in the third pipeline is carried and is used for external heat supply to the heat supply steam header.
2. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 1, wherein a water replenishing heater is arranged on the third pipeline, and steam in the third pipeline is directly conveyed to the heat supply steam header or conveyed to the heat supply steam header after heat exchange through the water replenishing heater.
3. The industrial steam supply system capable of improving the flexibility of the coal-fired unit as claimed in claim 2, wherein a heat storage tank is arranged on the second pipeline, the heat storage tank is a hot and cold water separated heat storage tank, cold water in the heat storage tank comes from demineralized water, and the cold demineralized water in the heat storage tank is conveyed into the heat exchanger to exchange heat with steam in the second pipeline, is heated and then returns to the heat storage tank to be stored in a hot water mode.
4. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 3, wherein hot water in the heat storage tank is directly conveyed to a deaerator to be used as water for the deaerator, or the hot water in the heat storage tank is conveyed to the water supplementing heater to exchange heat with steam in the third pipeline and then enters the deaerator after being heated.
5. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 1, wherein a high-side stop valve and a high-side temperature-reducing pressure-reducing valve are further arranged on the high-side pipeline, a part of main steam on the main steam pipeline flows into the high-side pipeline through the high-side stop valve, and exhausted steam after the small back pressure machine works enters the boiler reheater through the high-side temperature-reducing pressure-reducing valve.
6. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 1, wherein a heat exchanger inlet stop valve and a heat exchanger outlet stop valve are respectively arranged at two ends of the heat exchanger on the second pipeline, and steam in the second pipeline enters the heat exchanger to release heat and reduce temperature through the heat exchanger inlet stop valve and the heat exchanger outlet stop valve and then enters the condenser.
7. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 4, wherein part of steam discharged by the boiler reheater enters a low-side pipeline, a low-side stop valve A is arranged on the low-side pipeline, the steam passes through the low-side pipeline and then is divided into the first pipeline and a reheat steam extraction pipeline, the reheat steam extraction pipeline is divided into a second pipeline and a third pipeline, a low-side temperature and pressure reducing valve and a low-side stop valve B are arranged on the first pipeline, and the steam in the first pipeline is subjected to temperature and pressure reduction through the low-side temperature and pressure reducing valve and the low-side stop valve B and then enters the condenser; and a reheating steam extraction temperature-reducing pressure-reducing valve is arranged on the third pipeline, and steam in the third pipeline is directly fed into the heat supply steam header after being subjected to temperature and pressure reduction through the reheating steam extraction temperature-reducing pressure-reducing valve.
8. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 7, wherein a water supplement heater inlet electric door and a water supplement heater outlet electric door are respectively arranged at two ends of the water supplement heater, and a water supplement heater bypass electric door connected with the water supplement heater in parallel is arranged at the downstream of the reheating steam extraction temperature and pressure reducing valve on the third pipeline.
9. The industrial steam supply system capable of improving the flexibility of the coal-fired unit according to claim 8, wherein a water supplementing bypass inlet electric door is arranged on a pipeline connecting the heat storage tank and the water supplementing heater, a water supplementing main pipeline electric door is arranged on a pipeline connecting the heat storage tank and the deaerator, and a water supplementing bypass outlet electric door is arranged on a pipeline connecting the water supplementing heater and the deaerator.
10. The method of any one of claims 1 to 9 for an industrial steam supply system capable of improving flexibility of a coal-fired unit, wherein the steam in the third pipeline is used for meeting the steam demand of industrial heat users during the steam peak period, and the method comprises the following steps:
the method comprises the following steps: opening the high-side stop valve, controlling the steam flow in the high-side pipeline through the high-side temperature and pressure reducing valve, simultaneously applying work to the steam through the small back pressure machine, and enabling the exhausted steam after the work is applied by the small back pressure machine to enter the boiler reheater;
step two: open low other stop valve A and reheat extraction pressure and temperature reducing valve, steam in the boiler reheater passes through reheat extraction pressure and temperature reducing valve adjusts and gets into after meeting user's demand pressure and temperature the third pipeline, steam in the third pipeline passes through moisturizing heater bypass electrically operated gate directly gets into the heat supply steam header, perhaps steam in the third pipeline passes through get into behind the moisturizing heater the heat supply steam header.
11. The method for improving the flexibility of the industrial steam supply system of the coal-fired unit according to any one of claims 1 to 9, wherein the thermoelectric decoupling is realized by using the second pipeline and the heat storage tank, and the method comprises the following steps:
the method comprises the following steps: opening the high-side stop valve, controlling the steam flow in the high-side pipeline through the high-side temperature and pressure reducing valve, simultaneously applying work to steam through the small back-pressure machine, and enabling exhaust steam after the small back-pressure machine applies work to enter the boiler reheater;
step two: opening low side stop valve A with heat exchanger entry stop valve, steam in the boiler reheater gets into the second pipeline, steam in the second pipeline gets into open after the heat exchanger is exothermic the cooling heat exchanger export stop valve gets into the condenser, the demineralized water heat transfer in the heat exchanger is heated up the back storage in the heat-retaining jar.
12. The industrial steam supply method capable of improving the flexibility of the coal-fired unit according to claim 11, wherein when the second pipeline is not subjected to reheat steam extraction, the water supplementing bypass inlet electric door and the water supplementing bypass outlet electric door are closed, the water supplementing bypass main pipeline electric door is opened, and hot water in the heat storage tank directly enters the deaerator to serve as water supplement; when reheating steam extraction is carried out in the second pipeline, the water supplementing bypass inlet electric door and the water supplementing bypass outlet electric door are opened, the water supplementing bypass main circuit electric door is closed, and hot water in the heat storage tank enters the deaerator as water supplement after the temperature of the water supplementing heater is increased.
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