CN110925744A - System for recycling bypass flue gas heat from heat conducting oil of cold flue gas recirculation unit and control method - Google Patents
System for recycling bypass flue gas heat from heat conducting oil of cold flue gas recirculation unit and control method Download PDFInfo
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- CN110925744A CN110925744A CN201911267546.2A CN201911267546A CN110925744A CN 110925744 A CN110925744 A CN 110925744A CN 201911267546 A CN201911267546 A CN 201911267546A CN 110925744 A CN110925744 A CN 110925744A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
- F23B80/00—Combustion apparatus characterised by means creating a distinct flow path for flue gases or for non-combusted gases given off by the fuel
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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
- F22D1/36—Water and air preheating systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/06—Arrangements of devices for treating smoke or fumes of coolers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J15/00—Arrangements of devices for treating smoke or fumes
- F23J15/08—Arrangements of devices for treating smoke or fumes of heaters
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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
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/30—Technologies for a more efficient combustion or heat usage
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Abstract
The invention discloses a system for recovering heat of bypass flue gas by using heat conducting oil of a cold flue gas recirculation unit, which comprises a bypass flue gas cooling device, a recirculation cold flue gas heating device, a closed circulation oil pump, a heat conducting oil supplementing system, an adjusting baffle door, an air preheater and a boiler body, wherein the bypass flue gas cooling device is connected with the closed circulation oil pump; a first inlet of the bypass flue gas cooling device is communicated with the smoke outlet through an adjusting baffle door, and a first outlet of the bypass flue gas cooling device is communicated with a smoke outlet of the air preheater; the bypass flue gas cooling device is circularly communicated with the recirculation cold flue gas heating device; the recycling cold smoke heating device is communicated with the cold smoke recycling fan and a hearth cold ash hopper of the boiler body; the input end of the closed circulation oil pump is communicated with a second outlet of the recirculation cold smoke heating device, and the output end of the closed circulation oil pump is communicated with a second inlet of the bypass smoke cooling device; the output end of the heat conduction oil supplementing system is communicated with the eighth pipeline and is used for providing a supplemented heat conduction oil circulating medium; the smoke inlet of the air preheater is communicated with the smoke outlet of the boiler body.
Description
Technical Field
The invention relates to the field of unit efficiency improvement, in particular to a system for recovering heat of bypass flue gas by using heat conducting oil of a cold flue gas recirculation unit and a control method.
Background
Flue gas recirculation is a common method used to regulate the reheater outlet steam temperature when burning ashless or low ash fuels. At present, a large coal-fired unit for regulating the temperature of steam at the outlet of a reheater by adopting flue gas recirculation is mainly a secondary reheating unit. The double reheating unit is an internationally mature, efficient and low-pollution advanced coal-fired power generation technology, has good economic benefit and environmental protection characteristic, and has wide development prospect in China.
The cold smoke recycling is to pump out part of cold smoke (the temperature is about 70-150 ℃) from a dust remover or an induced draft fan and then to spray the smoke into a boiler cold ash bucket. When the cold smoke is sprayed from the cold ash hopper, the temperature of the hearth is reduced, the radiation heat exchange in the furnace is reduced, and the heat transfer of the convection heating surface is enhanced. On the premise of keeping the size of the existing hearth unchanged, the cold smoke recycling scheme can reduce the temperature level of the flue gas of the hearth and the heat absorption capacity of the water-cooled wall, improve the heat capacity and the convection heat transfer capacity of the flue gas, transfer part of heat absorbed by the water-cooled wall of the original hearth to the convection heating surface of the furnace for absorption, effectively control the temperature of the metal wall while ensuring the heat transfer capacity and the steam temperature of the convection heating surface, and ensure the heat absorption requirement of reheated steam on the premise of realizing safe operation of the heating surface.
The cold smoke recycling scheme has the defects that the total smoke of the boiler contains a certain amount of recycled smoke, the total smoke flow of the boiler is increased, the proportion of the smoke passing through the air preheater to the air is disordered, the temperature of the smoke at the outlet of the air preheater is increased due to redundant smoke heat, and the overall efficiency of the unit is reduced. In the early stage in China, the scheme usually needs to add a bypass flue in the air preheater, low-pressure condensed water and high-pressure feed water are selected as cooling media, the condensed water and the feed water are heated through the redundant flue gas heat in the bypass flue, and the steam consumption of the low-pressure heater and the high-pressure heater is reduced, so that the heat consumption of a turbine of a unit is reduced. Although the steam energy grade used by the high-pressure heater is higher, the steam energy grade used by the low-pressure heater is lower, and the overall utilization efficiency of the flue gas heat is limited.
The total flow of the flue gas passing through the air preheater is increased due to the existence of the amount of the recirculated flue gas in the cold flue gas recirculation unit, the proportion of the flue gas and the air is disordered, the temperature of the flue gas is increased, and the efficiency of the boiler is reduced. In the prior domestic unit, a bypass flue system is usually additionally arranged on an air preheater to absorb the heat of redundant flue gas (the unit adopts cold flue gas recirculation to cause the redundant flue gas to pass through the air preheater, namely the bypass flue gas), and the system comprises a bypass flue, an adjusting baffle door, a high-pressure water supply heat exchanger, a low-pressure condensed water heat exchanger, relevant valves, pipelines and the like. The total flow of the smoke is increased after the cold smoke is recycled, the carried heat is increased, in order to maintain the smoke discharge temperature of the unit, the redundant smoke is introduced into the bypass system of the air preheater, and the heat of partial smoke is absorbed by the feed water and the condensed water.
Therefore, the existing large-scale cold smoke recycling coal-fired unit adopting the air preheater bypass flue system has the following defects:
(1) the prior bypass flue system adopting the air preheater adopts condensation water with lower pressure and feed water with higher pressure as two cooling media respectively. According to the second law of thermodynamics, heat is converted from sensible heat of high-grade furnace flue gas into sensible heat of high-grade feed water and sensible heat of low-grade condensate water, certain irreversible loss exists in energy work-doing capacity, and the total utilization efficiency of the sensible heat of the flue gas is limited. Therefore, the mode of recovering the heat of the redundant smoke of the cold smoke recycling unit by adopting the existing air preheater bypass flue system has certain irrationality.
(2) The flue gas carries out heat exchange with low-pressure condensed water and high-pressure feed water respectively in the bypass flue, which is equivalent to that a condensed water heat exchanger and a low-pressure heater run in parallel, a feed water heat exchanger and a high-pressure heater run in parallel, and the design of a water side system is complex; meanwhile, the water supply flow/temperature, the condensate flow/temperature and the bypass flue gas flow/temperature are system variables, and the automatic control operation is complex.
(3) In the cold smoke recycling unit, the temperature of the circulating smoke is lower, generally about 90 ℃. When the cold smoke is sprayed into the hearth from the cold ash bucket at the lower part of the boiler, the stable working condition of the boiler combustion is easy to be impacted because the temperature difference between the cold smoke and the hearth is large, and the combustion of fuel is influenced.
Disclosure of Invention
The invention provides a system and a control method for recycling bypass flue gas heat by using heat conducting oil of a cold flue gas recycling unit, wherein a bypass flue gas cooling device, a recycling cold flue gas heating device, a closed circulating oil pump and a heat conducting oil supplementing system are arranged, the heat conducting oil is used as a circulating medium to convert high-grade bypass flue gas heat into same high-grade hearth flue gas heat, the technical defect problem of large irreversible loss caused by the fact that an original air preheater bypass flue system converts the bypass flue gas heat into a part of higher-grade water supply heat and a part of lower-grade condensed water heat is solved, the recycling efficiency of the bypass flue gas heat of the cold flue gas recycling unit can be improved, the power generation coal consumption of the unit is reduced, the energy-saving effect is obvious, and the economic benefit is obvious.
In order to solve the technical problem, an embodiment of the present invention provides a system for recovering heat from bypass flue gas by using heat transfer oil of a cold flue gas recirculation unit, including: the system comprises a boiler body, a first pipeline, an air preheater, a second pipeline, a low-temperature economizer, a third pipeline, a cold smoke recirculation fan, a recirculation cold smoke heating device, a fourth pipeline, a fifth pipeline, an air preheater bypass cooling device, a sixth pipeline, a seventh pipeline, a closed circulation oil pump, an eighth pipeline and a ninth pipeline;
the first pipeline is communicated with a smoke outlet of the boiler body and a smoke inlet of the air preheater, the second pipeline is communicated with a smoke outlet of the air preheater and the low-temperature economizer, the third pipeline is communicated with the low-temperature economizer and a smoke inlet of the cold smoke recirculation fan, the fourth pipeline is communicated with a smoke outlet of the cold smoke recirculation fan and a first inlet of the recirculation cold smoke heating device, the fifth pipeline is communicated with a first outlet of the recirculation cold smoke heating device and a cold ash hopper of the boiler body, one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
a closed cycle subsystem comprising a recirculating cold flue heating device and an air preheater bypass cooling device: the first inlet of the recycling cold smoke heating device is communicated with the smoke outlet of the cold smoke recycling fan through a fourth pipeline, the first outlet of the recycling cold smoke heating device is communicated with the cold ash hopper of the boiler body through a fifth pipeline, and the recycling cold smoke heating device further comprises a second inlet and a second outlet which are communicated with each other; the first inlet of the air preheater bypass cooling device is communicated with the smoke outlet of the boiler body through a sixth pipeline, the first outlet of the air preheater bypass cooling device is communicated with the second pipeline through a seventh pipeline, and the air preheater bypass cooling device further comprises a second inlet and a second outlet which are communicated with each other;
the closed circulation subsystem further comprises an eighth pipeline, a ninth pipeline and a closed circulation oil pump, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
the air preheater bypass cooling subsystem comprises a sixth pipeline, an air preheater bypass cooling device and a seventh pipeline, wherein one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline.
Preferably, the closed circulation subsystem further comprises a tenth pipeline;
one end of the tenth pipeline is communicated with the eighth pipeline, and the other end of the tenth pipeline is communicated with a heat conduction oil supplementing system.
Preferably, the air preheater bypass cooling subsystem further comprises a regulating gate, and the regulating gate is disposed on the sixth pipeline.
As a preferred scheme, the system for recovering heat from the bypass flue gas by using the heat transfer oil of the cold flue gas recirculation unit further comprises a plurality of temperature detection devices;
a first temperature detection device is arranged on the first inlet side of the recirculation cold smoke heating device;
a second temperature detection device is arranged on the first outlet side of the recirculation cold smoke heating device;
a third temperature detection device is arranged on the second inlet side of the recirculation cold smoke heating device;
a fourth temperature detection device is arranged on the second outlet side of the recirculation cold smoke heating device;
a fifth temperature detection device is arranged on the first inlet side of the air preheater bypass cooling device;
a sixth temperature detection device is arranged on the first outlet side of the air preheater bypass cooling device;
and a seventh temperature detection device is arranged on the smoke outlet side of the air preheater.
As a preferred scheme, the closed circulation subsystem further comprises a flow detection device;
and the ninth pipeline between the second inlet of the air preheater bypass cooling device and the closed circulating oil pump is provided with one flow detection device.
As a preferred scheme, the system for recycling the heat of the bypass flue gas by the heat transfer oil of the cold flue gas recirculation unit further comprises a control system, wherein the control system comprises a main controller, and the main controller is electrically connected with the plurality of temperature detection devices, the flow detection device, the closed circulation oil pump and the regulating valve respectively.
The embodiment of the invention also provides a method for controlling the heat quantity of the heat conducting oil recovery bypass flue gas of the cold smoke recycling unit, which is used for controlling the system for controlling the heat quantity of the heat conducting oil recovery bypass flue gas of the cold smoke recycling unit, and comprises the following steps:
detecting the smoke temperature of the smoke outlet side of the air preheater;
controlling the flow of the flue gas entering the bypass cooling subsystem of the air preheater through the opening of an adjusting door according to the temperature of the flue gas at the side of the flue gas outlet of the air preheater; when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is higher than a first preset temperature, controlling to increase the flow of the flue gas entering the bypass cooling subsystem of the air preheater, and when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is lower than the first preset temperature, controlling to decrease the flow of the flue gas entering the bypass cooling subsystem of the air preheater;
detecting a flue gas temperature at the first outlet side of the air preheater bypass cooling device; detecting a circulating oil temperature at the second inlet side of the recirculating cold smoke heating apparatus and a circulating oil temperature at the second outlet side of the recirculating cold smoke heating apparatus;
controlling the flow of the closed circulation oil pump according to the temperature of the flue gas on the first outlet side of the air preheater bypass cooling device; when the smoke temperature of the first outlet side of the air preheater bypass cooling device is higher than a second preset temperature, the temperature of circulating oil is maintained, the flow of the closed circulating oil pump is controlled to be increased, and when the smoke temperature of the first outlet side of the air preheater bypass cooling device is lower than the second preset temperature, the temperature of the circulating oil is maintained, and the flow of the closed circulating oil pump is controlled to be reduced.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the heat-conducting oil is used as a circulation medium, the bypass flue gas of the cold flue gas recirculation unit releases heat in the bypass flue gas cooling device to cool, and the circulation heat-conducting oil absorbs heat in the bypass flue gas cooling device to heat; the circulating heat-conducting oil releases heat to cool in the recirculating cold smoke heating device, and the recirculating cold smoke absorbs heat to heat in the recirculating cold smoke heating device; the circulating heat-conducting oil reciprocates between the bypass flue gas cooling device and the recirculating cold smoke heating device under the driving action of the closed circulating oil pump to complete the circulating heat absorption-heat release process, and continuously transfers the bypass flue gas heat into the recirculating cold smoke heat to be carried into a boiler hearth; in addition, a heat conduction oil supplementing system is arranged to provide a small amount of heat conduction oil supplement for the closed circulating oil system. According to the invention, by arranging the bypass flue gas cooling device, the recycling cold smoke heating device, the closed circulating oil pump and the heat conduction oil supplementing system, the heat conduction oil is used as a circulating medium to convert high-grade bypass flue gas heat in the cold smoke recycling unit into same high-grade hearth flue gas heat, the technical defect of large irreversible loss caused by the fact that the original air preheater bypass flue system converts the bypass flue gas heat into a part of higher-grade water supply heat and a part of lower-grade condensed water heat is avoided, the recycling efficiency of the bypass flue gas heat of the cold smoke recycling unit can be improved, the unit power generation coal consumption is reduced, the energy saving effect is obvious, and the economic benefit is obvious.
The invention selects the synthetic heat transfer oil with high heat transfer coefficient, good thermal stability, high boiling point, low condensation point, no toxicity and no corrosiveness as the circulating working medium, has the heat transfer performance of high temperature and low pressure at the working temperature of about 300-320 ℃ in a normal pressure state, can reduce the design pressure grade of the whole bypass flue gas heat recovery system, and greatly reduces the initial investment of the system.
Drawings
FIG. 1: the structural schematic diagram of a system for recovering heat of bypass flue gas by using heat conducting oil of a cold flue gas recirculation unit in the embodiment of the invention is shown;
wherein the reference numbers of the drawings in the specification are as follows:
1. a bypass flue gas cooling device; 111. a second outlet of the bypass flue gas cooling device; 112. a first outlet of the bypass flue gas cooling device; 121. a first inlet of a bypass flue gas cooling device; 122. a second inlet of the bypass flue gas cooling device;
2. a recirculating cold smoke heating means; 211. a first outlet of the recirculating cold smoke heating means; 212. a second outlet of the recirculating cold smoke heating means; 221. a second inlet of the recirculating cold smoke heating means; 222. a first inlet of a recirculating cold smoke heating means;
3. a closed circulation oil pump; 4. a heat transfer oil supplementing system; 5. adjusting the flapper door; 6. an air preheater; 7. a boiler body;
8. a low-temperature economizer; 81. a water inlet end of the low-temperature economizer; 82. the water outlet end of the low-temperature economizer;
9. an electric dust collector; 10. a cold smoke recirculation fan; 11. an induced draft fan; 12. an SCR system; 13. a low-nitrogen burner; 01. a first conduit; 02. a second conduit; 03. a third pipeline; 04. a fourth conduit; 05. a fifth pipeline; 06. a sixth pipeline; 07. a seventh pipe; 08. an eighth conduit; 09. a ninth conduit; 010. a tenth conduit;
t1, a first temperature detection device; t2, a second temperature detection device; t3, third temperature detection means; t4, a fourth temperature detection device; t5, a fifth temperature detection device; t6, a sixth temperature detection device; t7, a seventh temperature detection device;
and Q, a flow detection device.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, 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 invention.
The following are explanations of terms appearing in the following technical solutions: cooling the smoke: the flue gas after a dust remover or an induced draft fan takes a large coal-fired unit provided with a low-temperature electrostatic dust remover as an example, and the dust concentration of the flue gas after passing through the dust remover or the induced draft fan is less than 100mg/Nm3The temperature is about 70-150 ℃. And (3) recycling of cold smoke: the cold smoke generated after the dust remover or the induced draft fan is sent into the boiler furnace again after being boosted by the recirculation fan. A recirculation fan: the invention relates to equipment for circulating part of cold smoke. A recycling flue: the flue is extracted from a dust remover or an induced draft fan, enters a recirculation fan for boosting, is heated in a heat exchanger and then returns to a boiler furnace. Bypass flue gas cooling device: a heat exchange device for transferring the heat of bypass flue gas of an air preheater to external closed circulation heat conduction oil adopts a flue gas-oil heat exchanger. Recirculating cold flue heating apparatus: the heat exchange device for transferring the heat of the external closed circulation heat conduction oil to the recirculating cold smoke adopts an oil-smoke heat exchanger. A closed circulation oil pump: the invention relates to a device for driving heat conduction oil in closed circulation. Heat conduction oil: the working medium for the circulating heat exchange in the invention is heat conducting oil with high heat transfer coefficient, good thermal stability, high boiling point, low condensation point, no toxicity (or low toxicity) and no corrosiveness, such as synthetic heat conducting oil, and the optimal working temperature is-20 ℃ to 320 ℃. Flue gas treatment equipment: the method is used for treating and boosting the flue gas at the outlet of the air preheater and comprises a low-temperature economizer, an electric dust remover, an induced draft fan and the like.
Referring to fig. 1, a system for recovering heat from bypass flue gas by using heat transfer oil of a cold flue gas recirculation unit according to a preferred embodiment of the present invention includes: the system comprises a boiler body, a first pipeline, an air preheater, a second pipeline, a low-temperature economizer, a third pipeline, a cold smoke recirculation fan, a recirculation cold smoke heating device, a fourth pipeline, a fifth pipeline, an air preheater bypass cooling device, a sixth pipeline, a seventh pipeline, a closed circulation oil pump, an eighth pipeline and a ninth pipeline;
the first pipeline is communicated with a smoke outlet of the boiler body and a smoke inlet of the air preheater, the second pipeline is communicated with a smoke outlet of the air preheater and the low-temperature economizer, the third pipeline is communicated with the low-temperature economizer and a smoke inlet of the cold smoke recirculation fan, the fourth pipeline is communicated with a smoke outlet of the cold smoke recirculation fan and a first inlet of the recirculation cold smoke heating device, the fifth pipeline is communicated with a first outlet of the recirculation cold smoke heating device and a cold ash hopper of the boiler body, one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
a closed cycle subsystem comprising a recirculating cold flue heating device and an air preheater bypass cooling device: the first inlet of the recycling cold smoke heating device is communicated with the smoke outlet of the cold smoke recycling fan through a fourth pipeline, the first outlet of the recycling cold smoke heating device is communicated with the cold ash hopper of the boiler body through a fifth pipeline, and the recycling cold smoke heating device further comprises a second inlet and a second outlet which are communicated with each other; the first inlet of the air preheater bypass cooling device is communicated with the smoke outlet of the boiler body through a sixth pipeline, the first outlet of the air preheater bypass cooling device is communicated with the second pipeline through a seventh pipeline, and the air preheater bypass cooling device further comprises a second inlet and a second outlet which are communicated with each other;
the closed circulation subsystem further comprises an eighth pipeline, a ninth pipeline and a closed circulation oil pump, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
the air preheater bypass cooling subsystem comprises a sixth pipeline, an air preheater bypass cooling device and a seventh pipeline, wherein one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline.
The heat-conducting oil is used as a circulation medium, the bypass flue gas of the cold flue gas recirculation unit releases heat in the bypass flue gas cooling device to cool, and the circulation heat-conducting oil absorbs heat in the bypass flue gas cooling device to heat; the circulating heat-conducting oil releases heat to cool in the recirculating cold smoke heating device, and the recirculating cold smoke absorbs heat to heat in the recirculating cold smoke heating device; the circulating heat-conducting oil reciprocates between the bypass flue gas cooling device and the recirculating cold smoke heating device under the driving action of the closed circulating oil pump to complete the circulating heat absorption-heat release process, and continuously transfers the bypass flue gas heat into the recirculating cold smoke heat to be carried into a boiler hearth; in addition, a heat conduction oil supplementing system is arranged to provide a small amount of heat conduction oil supplement for the closed circulating oil system. The invention has the advantages that the bypass flue gas cooling device, the recirculation cold smoke heating device, the closed circulation oil pump and the heat conduction oil supplementing system are arranged, the heat conduction oil is used as a circulation medium to convert the high-grade bypass flue gas heat in the unit into the same high-grade hearth flue gas heat, the technical defect problem of large irreversible loss caused by the fact that the original air preheater bypass flue system converts the bypass flue gas heat into a part of higher-grade water supply heat and a part of lower-grade condensed water heat is solved, the recycling efficiency of the bypass flue gas heat of the cold smoke recirculation unit can be improved, the power generation coal consumption of the unit is reduced, the energy-saving effect is obvious, and the economic benefit is obvious.
In this embodiment, the closed cycle subsystem further includes a tenth pipe;
one end of the tenth pipeline is communicated with the eighth pipeline, and the other end of the tenth pipeline is communicated with a heat conduction oil supplementing system.
In this embodiment, the air preheater bypass cooling subsystem further comprises a damper disposed on the sixth duct.
In this embodiment, the system for recovering heat from the bypass flue gas by using the heat transfer oil of the cold flue gas recirculation unit further comprises a plurality of temperature detection devices;
a first temperature detection device is arranged on the first inlet side of the recirculation cold smoke heating device;
a second temperature detection device is arranged on the first outlet side of the recirculation cold smoke heating device;
a third temperature detection device is arranged on the second inlet side of the recirculation cold smoke heating device;
a fourth temperature detection device is arranged on the second outlet side of the recirculation cold smoke heating device;
a fifth temperature detection device is arranged on the first inlet side of the air preheater bypass cooling device;
a sixth temperature detection device is arranged on the first outlet side of the air preheater bypass cooling device;
and a seventh temperature detection device is arranged on the smoke outlet side of the air preheater.
In this embodiment, the closed-cycle subsystem further includes a flow detection device;
and the ninth pipeline between the second inlet of the air preheater bypass cooling device and the closed circulating oil pump is provided with one flow detection device.
In this embodiment, the system for recycling heat of bypass flue gas from heat transfer oil of the cold smoke recycling unit further comprises a control system, wherein the control system comprises a main controller, and the main controller is respectively connected with the plurality of temperature detection devices, the plurality of flow detection devices, the plurality of closed circulation oil pumps and the plurality of regulating valves.
The embodiment of the invention also provides a method for controlling the heat quantity of the heat conducting oil recovery bypass flue gas of the cold smoke recycling unit, which is used for controlling the system for controlling the heat quantity of the heat conducting oil recovery bypass flue gas of the cold smoke recycling unit, and comprises the following steps:
s1, detecting the smoke temperature at the smoke outlet side of the air preheater;
s2, controlling the flow rate of the flue gas entering the bypass cooling subsystem of the air preheater through the opening of an adjusting valve according to the temperature of the flue gas at the side of the flue gas outlet of the air preheater; when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is higher than a first preset temperature, controlling to increase the flow of the flue gas entering the bypass cooling subsystem of the air preheater, and when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is lower than the first preset temperature, controlling to decrease the flow of the flue gas entering the bypass cooling subsystem of the air preheater;
s3, detecting the temperature of the flue gas on the first outlet side of the air preheater bypass cooling device; detecting a circulating oil temperature at the second inlet side of the recirculating cold smoke heating apparatus and a circulating oil temperature at the second outlet side of the recirculating cold smoke heating apparatus;
s4, controlling the flow rate of the closed circulation oil pump according to the temperature of the flue gas on the first outlet side of the air preheater bypass cooling device; when the smoke temperature of the first outlet side of the air preheater bypass cooling device is higher than a second preset temperature, the temperature of circulating oil is maintained, the flow of the closed circulating oil pump is controlled to be increased, and when the smoke temperature of the first outlet side of the air preheater bypass cooling device is lower than the second preset temperature, the temperature of the circulating oil is maintained, and the flow of the closed circulating oil pump is controlled to be reduced.
In order to better evaluate the effectiveness of the scheme of the invention, a plurality of temperature monitoring points and flow monitoring points are arranged in the system for acquiring data for analysis. As shown in fig. 1, T1 to T7 are all temperature monitoring points for acquiring temperature data of the position; and Q is a flow monitoring point and is used for acquiring flow data at the position.
The following will be described in detail with reference to the efficiency improvement system of the novel cold smoke recycling unit.
Taking heat conduction oil as an example of a circulating medium, on the premise of satisfying the requirement of fully enhancing heat exchange of circulating heat conduction oil, bypass flue gas and recirculating cold flue gas, the invention prevents the closed circulating heat conduction oil from generating vaporization phenomenon under normal pressure, and the supercooling degree of the closed circulating heat conduction oil is typically selected to be 10-50 ℃, so that the temperature of the circulating heat conduction oil after absorbing the heat of a bypass flue is temporarily set to be 320 ℃.
The closed circulation heat conduction oil and the bypass flue gas carry out sufficient heat exchange in the bypass flue gas cooling device: the temperature of the circulating heat-conducting oil at the inlet of the bypass flue gas cooling device is temporarily considered to be about 110 ℃, and after the heat of the bypass flue gas is absorbed, the temperature of the circulating heat-conducting oil is increased to about 320 ℃; the bypass flue gas temperature, namely the inlet flue gas temperature of the bypass flue gas cooling device, is temporarily considered about 360 ℃, and after the heat of the flue gas is released, the bypass flue gas temperature is reduced to about 150 ℃.
After absorbing heat and raising temperature, the circulating heat-conducting oil enters a recirculating cold smoke heating device under the drive of a closed circulating oil pump; and after cooling, the bypass flue gas is mixed with the flue gas at the outlet of the air preheater and enters the low-temperature electrostatic dust collector.
The closed circulation heat conduction oil and the recirculation cold smoke perform sufficient heat exchange in the recirculation cold smoke heating device: the temperature of the circulating heat transfer oil at the inlet of the recycling cold smoke heating device is about 320 ℃, and after the heat of the circulating heat transfer oil is released, the temperature of the circulating heat transfer oil is reduced to about 110 ℃; the temperature of the recirculated cold smoke at the inlet of the recirculated cold smoke heating device is about 90 ℃, and after the heat of the circulated heat transfer oil is absorbed, the temperature of the recirculated cold smoke rises to about 300 ℃, and then the recirculated cold smoke enters a hearth from a cold ash hopper at the lower part of the boiler.
The working process is continuously carried out, the circulating heat-conducting oil is used as a working medium, the circulating heat-conducting oil is driven by the circulating oil pump to reciprocate between the bypass flue gas cooling device and the recirculation cold smoke heating device to complete the circulating heat absorption-heat release process, the bypass flue gas heat is continuously recovered and transferred into the recirculation cold smoke heat through the bypass flue gas cooling device and the recirculation cold smoke heating device, and the recirculation cold smoke temperature at the inlet of the cold ash hopper at the lower part of the boiler is increased.
After the redundant flue gas generated by the cold smoke recycling unit is introduced into the bypass flue to become bypass flue gas, the flow rate of the flue gas in the air preheater is reduced, the ratio of the flue gas to the air is well matched, the comprehensive exhaust temperature of the unit is maintained at a normal level, the boiler efficiency is increased to some extent, and the efficiency of the cold smoke recycling unit is improved.
Taking typical parameters as an example, the oil temperature of the closed circulation heat transfer oil at the inlet of the bypass flue gas cooling device and the outlet of the recirculation cold smoke heating device is 110 ℃ below zero, the oil temperature of the closed circulation heat transfer oil at the outlet of the bypass flue gas cooling device and the inlet of the recirculation cold smoke heating device is 320 ℃ below zero, and a certain heat exchange end difference is kept between the oil temperature and the cooled working medium or the heated working medium; the bypass flue gas temperature at the inlet of the bypass flue gas cooling device is about-360 ℃, and after the heat of the flue gas is released, the temperature of the bypass flue gas is reduced to about-150 ℃; the temperature of the recirculated cold smoke at the inlet of the recirculated cold smoke heating device is about 90 ℃, and the temperature of the recirculated cold smoke is raised to about 300 ℃ after the heat of the circulated heat transfer oil is absorbed.
The system for recycling the heat of the bypass flue gas by the heat transfer oil of the cold smoke recycling unit is provided with necessary temperature and flow detection points, wherein a closed circulating heat transfer oil pipeline is provided with a circulating heat transfer oil flow measurement point and a temperature measurement point, and circulating heat transfer oil temperatures T1 and T2 and a circulating heat transfer oil flow Q at an inlet and an outlet of the recycling cold smoke heating device are monitored; the inlet and outlet bypass flues of the bypass flue gas cooling device are provided with necessary temperature detection points, and the inlet and outlet flue gas temperatures T3 and T4 of the bypass flue gas cooling device are monitored; the outlet flue of the air preheater is also provided with a necessary temperature detection point for monitoring the exhaust temperature T5 of the air preheater; the inlet and outlet recirculation flue of the recirculation cold smoke heating device is provided with necessary temperature detection points, and the flue gas temperatures T6 and T7 of the inlet and outlet of the recirculation cold smoke heating device are monitored.
(1) The closed circulation heat transfer oil temperature T1 at the inlet of the bypass flue gas cooling device and the outlet of the recirculation cold flue gas heating device is as follows:
the closed circulation heat transfer oil temperature T1 at the inlet of the bypass flue gas cooling device and the outlet of the recirculation cold flue gas heating device is generally-110 ℃.
(2) The closed circulation heat transfer oil temperature T2 at the outlet of the bypass flue gas cooling device and the inlet of the recirculation cold flue gas heating device is as follows:
the closed cycle heat transfer oil temperature T2 at the outlet of the bypass flue gas cooling device and the inlet of the recirculation cold flue gas heating device is generally-320 ℃.
(3) Bypass flue gas temperature T3, T4 at the inlet and outlet of the bypass flue gas cooling device:
the bypass flue gas temperature T3 at the inlet of the bypass flue gas cooling device is related to the furnace flue gas temperature, typically-360 ℃.
The bypass flue gas temperature T4 at the outlet of the bypass flue gas cooling device is related to the flow of the circulating heat transfer oil under the condition that the temperature of the circulating heat transfer oil is certain, and the adjustment can be realized only by correspondingly adjusting the flow Q of the circulating heat transfer oil, generally to 150 ℃.
The flow of circulating heat conducting oil can be adjusted through the closed circulating oil pump, and under the condition of maintaining the oil temperature of an inlet and an outlet of the bypass flue gas cooling device unchanged, the flow of the heat conducting oil is increased, so that the exhaust gas temperature of a bypass flue is reduced; and reducing the flow of the heat conducting oil, and increasing the exhaust smoke temperature of the bypass flue.
(4) Air preheater exhaust gas temperature T5:
the exhaust gas temperature T5 of the air preheater is related to the flow of the exhaust gas under the condition that the inlet gas temperature is constant, the adjustment can be realized only by correspondingly adjusting the distribution of the flow of the exhaust gas of the air preheater and the bypass through a baffle adjusting door on a bypass flue of the air preheater, and the exhaust gas temperature is maintained to be the same as that of the air preheater of a conventional unit (a unit without cold smoke recirculation), and is generally-130 ℃.
The flue gas flow of the air preheater can be adjusted through the baffle adjusting door, and the flue gas flow is increased, so that the flue gas temperature of the air preheater is increased; and when the flow of the flue gas is reduced, the temperature of the flue gas discharged by the air preheater is increased.
(5) Inlet and outlet flue gas temperatures T6, T7 of the recirculation cold smoke heating device:
the inlet flue gas temperature T6 of the recirculation cold flue gas heating device is related to the inlet/outlet flue gas temperature of the induced draft fan, and is typically-90 ℃ when the unit employs a low-temperature electrostatic precipitator.
The temperature of the flue gas at the outlet of the recirculation cold flue gas heating device, T7, is generally-300 ℃ after absorbing the heat of the circulation heat transfer oil, and the temperature mainly depends on the heat of the closed circulation heat transfer oil released by the bypass flue gas.
(6) In conclusion, the bypass flue gas mass flow and the recirculated flue gas mass flow are basically the same under the design working condition of the system for recycling the heat of the bypass flue gas by using the cold flue gas recirculation heat conduction oil, the matching between the flue gas flow in the air preheater and the air flow is good, the increase of the flue gas flow caused by the cold flue gas recirculation is avoided, the exhaust temperature of the air preheater is increased, the closed circulation heat conduction oil is used as a cold source and a heat source respectively to convert the bypass flue gas heat into the heat of the recirculated cold flue gas to reenter a hearth, the heat of the bypass flue gas with high grade is converted into the heat of the hearth flue gas with the same high grade, and the main defect that the bypass flue system of the original air preheater (the heat of the bypass flue gas is converted into a part of the water.
Because the bypass flue gas mass flow is basically the same as the mass flow of the recirculated flue gas, the selection of the circulating heat conduction oil temperatures T1 and T2 directly influences the amount of heat of the bypass flue gas recovered by the system under the condition that the inlet flue gas temperature of the bypass flue gas cooling device and the inlet flue gas temperature of the recirculated cold flue gas heating device are fixed. In order to effectively prevent the circulation heat conduction oil from generating vaporization phenomenon under the normal pressure state, the supercooling degree between the oil temperature of the high-temperature circulation heat conduction oil and the boiling point of the heat conduction oil is kept to be about 10-50 ℃, meanwhile, the temperature end difference required by heat exchange between the high-temperature circulation heat conduction oil and the temperature (350-390 ℃) of the flue gas at the inlet of the bypass flue gas is about 20-40 ℃ (the bypass flue gas heat exchange device is limited by the resistance of the flue gas of the equipment, the required heat exchange end difference is slightly larger), the temperature end difference required by heat exchange between the high-temperature circulation heat conduction oil and the temperature of the flue gas at the outlet of the recirculation cold flue gas heating device is about 20 ℃; the temperature difference required by heat exchange between the low-temperature circulating heat conduction oil and the temperature (130-150 ℃) of the flue gas at the outlet of the bypass flue gas is about 20-40 ℃ (the bypass flue gas heat exchange device is limited by the resistance of the flue gas of the equipment, and the difference between the required heat exchange ends is slightly larger), meanwhile, the temperature difference required by heat exchange between the low-temperature circulating heat conduction oil and the temperature (about 90 ℃) of the flue gas at the inlet of the recirculation cold flue gas heating device is about 20 ℃, and the lower the temperature of the low-temperature circulating heat conduction oil is, the more the bypass flue gas heat is.
Taking a typical system as an example, according to the inlet flue gas temperature T3 of the unit bypass flue gas cooling device and the inlet flue gas temperature T6 of the recirculation cold flue gas heating device, the proper low-temperature circulation heat transfer oil temperature T1 and the proper high-temperature circulation heat transfer oil temperature T2 are automatically calculated and preset; according to the feedback of the exhaust gas temperature T4 of the bypass flue gas cooling device, under the condition that the oil temperature of an inlet and an outlet of the bypass flue gas cooling device is not changed, namely the oil temperature of circulating heat conducting oil, the flow of the circulating heat conducting oil can be adjusted through a closed circulating oil pump, and the exhaust gas temperature T4 is maintained at about 150 ℃; according to the feedback of the exhaust gas temperature T5 of the air preheater, under the condition that the inlet gas temperature of the air preheater is constant, the flow rate of the exhaust gas of the bypass flue of the air preheater can be adjusted by controlling the baffle adjusting door of the bypass flue, and the exhaust gas temperature is maintained to be about 130 ℃. Through the control, the whole system can be always in the operation condition with the lowest cost, and a stable process is established.
The whole process flow can be incorporated into a power plant DCS control system or an independent PLC control system is arranged to realize an automatic control function. The DCS or the PLC control system acquires the oil temperatures T1 and T2 of circulating heat transfer oil, the temperatures T3 and T4 of bypass flue gas, the exhaust gas temperature T5 of an air preheater and the temperatures T6 and T7 of recirculated flue gas through a data acquisition card, and after internal operation of a processor of the control system, a control card is controlled to output control signals to a closed circulating oil pump and a bypass flue baffle adjusting door, the rotating speed of the circulating oil pump is adjusted to realize automatic control of the amount of circulating heat transfer oil, so that the exhaust gas temperature T4 of the bypass flue gas cooling device is maintained; and the automatic control of the flue gas flow distribution of the air preheater and the air preheater bypass is realized by adjusting the baffle adjusting door of the bypass flue, and the flue gas mass flow of the air preheater bypass is basically consistent with the mass flow of the recirculated flue gas, so that the exhaust gas temperature T5 of the air preheater is maintained.
Taking typical parameters as examples: (1) if the optimum bypass flue gas cooling device flue gas temperature is determined to be 150 ℃, then the flue gas temperature is kept cooled to 150 ℃ through feedback at a point T4. When the temperature T4 is higher than 150 ℃, adjusting the rotating speed of the circulating oil pump and increasing the flow of circulating heat conduction oil; when the temperature T4 is lower than 150 ℃, adjusting the rotating speed of the circulating oil pump and reducing the flow of circulating heat-conducting oil; (2) if the optimum air preheater flue gas temperature is determined to be 130 ℃, then the air preheater flue gas temperature is maintained at 130 ℃ by feedback at point T5. When the temperature of T5 is lower than 130 ℃, adjusting the opening of a bypass baffle plate, increasing the flue gas flow of an air preheater and reducing the flue gas flow of a bypass flue; and when the temperature T5 is higher than 130 ℃, adjusting the opening of a bypass baffle plate, reducing the flue gas flow of the air preheater and increasing the flue gas flow of a bypass flue.
The heat conduction oil is used as a circulation medium, a closed circulation system is adopted, the circulation medium absorbs heat (cools bypass flue gas temperature) at a bypass flue of the boiler air preheater and releases heat (heats and recycles cold flue gas temperature) at a cold flue gas recycling flue through different heat exchange devices, and the bypass flue gas heat in the bypass flue of the boiler air preheater is continuously transferred into the recycled cold flue gas of the cold flue gas recycling system under the driving of a circulation pump (or other driving equipment). The energy grade of the recirculated cold smoke is far higher than that of steam of a low-pressure heater and that of steam of a high-pressure heater, so that the heat utilization efficiency of the recirculated cold smoke is far higher than that of a domestic traditional system. Meanwhile, the boiling point (330 ℃) of the heat conduction oil is far higher than the boiling point (100 ℃) of water under the normal pressure state, and the heat conduction oil is heated to about 300-320 ℃ by the heat of the bypass flue gas under the normal pressure state without vaporization, so that the heat exchange device can be designed according to the normal pressure working condition, the wall thickness of a pipeline of equipment is greatly reduced, and the initial investment is reduced by more than 50%. In conclusion, compared with the traditional domestic air preheater bypass flue gas heat recovery energy-saving system, the invention can improve the utilization efficiency of the flue gas heat of the recovered bypass flue gas from about 30% to more than 60%, realizes the energy-saving and efficiency-improving of the cold smoke recycling unit, and simultaneously reduces the initial investment of equipment by more than 50%, thereby having remarkable economic benefit.
The invention has the advantages and effects that:
1. the invention converts the redundant high-grade bypass flue gas heat in the cold smoke recycling unit into the same high-grade hearth flue gas heat through the novel system and the related equipment, and avoids the main defect of large irreversible loss of the original air preheater bypass flue system (the bypass flue gas heat is converted into a part of higher-grade feed water heat and a part of lower-grade condensed water heat) to a certain extent.
2. According to the novel system and the related equipment, the smoke temperature of the recirculated cold smoke in the cold smoke recirculation unit is increased from about 90 ℃ to about 300 ℃, the temperature difference between the recirculated cold smoke and the hearth is reduced, the stable combustion working condition is prevented from being impacted, and good burnout of fuel is ensured.
3. The invention selects the synthetic heat transfer oil with high heat transfer coefficient, good thermal stability, high boiling point, low condensation point, no toxicity (or low toxicity) and no corrosiveness as the circulating working medium, the working temperature is about 300-320 ℃ in a normal state, the synthetic heat transfer oil has high-temperature low-pressure heat transfer performance, the design pressure grade of the whole bypass flue gas heat recovery system can be reduced, the wall thickness of a pipeline is greatly reduced, and the initial investment of the system is reduced.
4. The invention can improve the efficiency of the cold smoke recycling unit, reduce the coal consumption of the unit for power generation, reduce the initial investment of the system and has obvious economic benefit.
5. The bypass flue gas cooling device, the recirculation cold flue gas heating device, the closed circulation oil pump, the air preheater bypass flue, the adjusting baffle door and the like are conventional equipment, and domestic projects have certain operation and maintenance experience and can be operated safely and stably for a long time.
The invention aims to greatly improve the recycling efficiency of the bypass flue gas heat of the cold smoke recycling unit, thereby improving the efficiency of the cold smoke recycling unit, reducing the coal consumption of unit power generation, simultaneously reducing the influence of cold smoke recycling on the combustion of a hearth, and adopting heat transfer oil as a circulating medium, simplifying a circulating system into normal pressure design, reducing the initial investment of equipment, reducing the operation and maintenance workload and other factors.
Taking heat-conducting oil as a circulation medium as an example, the novel system for recycling the heat of the bypass flue gas by the cold flue gas recirculation unit comprises a bypass flue gas cooling device, a recirculation cold flue gas heating device, a closed circulation oil pump, related pipelines and valves, a heat-conducting oil supplementing system, related pipelines and valves, an air preheater bypass flue, a bypass flue gas adjusting baffle door and the like. The system takes heat-conducting oil as a circulating medium, the bypass flue gas of the cold flue gas recirculation unit releases heat in a bypass flue gas cooling device to cool, and the circulating heat-conducting oil absorbs heat in the bypass flue gas cooling device to heat; the circulating heat-conducting oil releases heat to cool in the recirculating cold smoke heating device, and the recirculating cold smoke absorbs heat to heat in the recirculating cold smoke heating device; the circulating heat conducting oil reciprocates between the bypass flue gas cooling device and the recirculation cold smoke heating device under the driving action of the closed circulating oil pump to complete the circulating heat absorption-heat release process, and the bypass flue gas heat is continuously transferred into the recirculation cold smoke heat to be carried into a boiler hearth. In addition, the invention is provided with a heat conduction oil supplement system, and a small amount of heat conduction oil supplement is provided for the closed type circulating oil system.
The invention converts high-grade bypass flue gas heat into same high-grade hearth flue gas heat through the novel system and the related equipment, and avoids the main defect of large irreversible loss of the original air preheater bypass flue system (converting the bypass flue gas heat into a part of higher-grade feed water heat and a part of lower-grade condensed water heat) to a certain extent. Meanwhile, the boiling point (330 ℃) of the heat conduction oil is far higher than the boiling point (100 ℃) of water under the normal pressure state, the heat conduction oil is heated to about 300-320 ℃ by the heat of the bypass flue gas under the normal pressure state without vaporization, and the heat exchange device can be designed according to the normal pressure working condition, so that the wall thickness of a pipeline of the equipment is reduced. In conclusion, the invention can improve the recycling efficiency of the bypass flue gas heat of the cold smoke recycling unit, reduce the coal consumption of unit power generation, reduce the initial investment of equipment and has obvious economic benefit.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (7)
1. The utility model provides a bypass flue gas heat system is retrieved to cold cigarette recycling unit conduction oil which characterized in that includes: the system comprises a boiler body, a first pipeline, an air preheater, a second pipeline, a low-temperature economizer, a third pipeline, a cold smoke recirculation fan, a recirculation cold smoke heating device, a fourth pipeline, a fifth pipeline, an air preheater bypass cooling device, a sixth pipeline, a seventh pipeline, a closed circulation oil pump, an eighth pipeline and a ninth pipeline;
the first pipeline is communicated with a smoke outlet of the boiler body and a smoke inlet of the air preheater, the second pipeline is communicated with a smoke outlet of the air preheater and the low-temperature economizer, the third pipeline is communicated with the low-temperature economizer and a smoke inlet of the cold smoke recirculation fan, the fourth pipeline is communicated with a smoke outlet of the cold smoke recirculation fan and a first inlet of the recirculation cold smoke heating device, the fifth pipeline is communicated with a first outlet of the recirculation cold smoke heating device and a cold ash hopper of the boiler body, one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
a closed cycle subsystem comprising a recirculating cold flue heating device and an air preheater bypass cooling device: the first inlet of the recycling cold smoke heating device is communicated with the smoke outlet of the cold smoke recycling fan through a fourth pipeline, the first outlet of the recycling cold smoke heating device is communicated with the cold ash hopper of the boiler body through a fifth pipeline, and the recycling cold smoke heating device further comprises a second inlet and a second outlet which are communicated with each other; the first inlet of the air preheater bypass cooling device is communicated with the smoke outlet of the boiler body through a sixth pipeline, the first outlet of the air preheater bypass cooling device is communicated with the second pipeline through a seventh pipeline, and the air preheater bypass cooling device further comprises a second inlet and a second outlet which are communicated with each other;
the closed circulation subsystem further comprises an eighth pipeline, a ninth pipeline and a closed circulation oil pump, the eighth pipeline is communicated with a second outlet of the air preheater bypass cooling device and a second inlet of the recirculation cold smoke heating device, the ninth pipeline is communicated with a second outlet of the recirculation cold smoke heating device and a second inlet of the air preheater bypass cooling device, and the closed circulation oil pump is arranged in the ninth pipeline;
the air preheater bypass cooling subsystem comprises a sixth pipeline, an air preheater bypass cooling device and a seventh pipeline, wherein one end of the sixth pipeline is communicated with the first pipeline, the other end of the sixth pipeline is communicated with a first inlet of the air preheater bypass cooling device, one end of the seventh pipeline is communicated with a first outlet of the air preheater bypass cooling device, and the other end of the seventh pipeline is communicated with the second pipeline.
2. The heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit of claim 1, wherein the closed cycle subsystem further comprises a tenth pipeline;
one end of the tenth pipeline is communicated with the eighth pipeline, and the other end of the tenth pipeline is communicated with a heat conduction oil supplementing system.
3. The system for recycling heat transfer oil of a cold smoke recycling unit to bypass flue gas heat as claimed in claim 2, wherein the air preheater bypass cooling subsystem further comprises an adjusting door, and the adjusting door is disposed on the sixth pipeline.
4. The heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit of claim 3, wherein the heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit further comprises a plurality of temperature detection devices;
a first temperature detection device is arranged on the first inlet side of the recirculation cold smoke heating device;
a second temperature detection device is arranged on the first outlet side of the recirculation cold smoke heating device;
a third temperature detection device is arranged on the second inlet side of the recirculation cold smoke heating device;
a fourth temperature detection device is arranged on the second outlet side of the recirculation cold smoke heating device;
a fifth temperature detection device is arranged on the first inlet side of the air preheater bypass cooling device;
a sixth temperature detection device is arranged on the first outlet side of the air preheater bypass cooling device;
and a seventh temperature detection device is arranged on the smoke outlet side of the air preheater.
5. The heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit of claim 4, wherein the closed circulation subsystem further comprises a flow detection device;
and the ninth pipeline between the second inlet of the air preheater bypass cooling device and the closed circulating oil pump is provided with one flow detection device.
6. The heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit as claimed in claim 5, wherein the heat transfer oil recovery bypass flue gas heat system of the cold smoke recycling unit further comprises a control system, the control system comprises a main controller, and the main controller is electrically connected with the plurality of temperature detection devices, the flow detection device, the closed circulation oil pump and the regulating gate respectively.
7. A method for controlling heat of bypass flue gas recovered by heat transfer oil of a cold smoke recycling unit is characterized by being used for controlling the heat system of bypass flue gas recovered by heat transfer oil of the cold smoke recycling unit as set forth in any one of claims 1-6, and comprising the following steps:
detecting the smoke temperature of the smoke outlet side of the air preheater;
controlling the flow of the flue gas entering the bypass cooling subsystem of the air preheater through the opening of an adjusting door according to the temperature of the flue gas at the side of the flue gas outlet of the air preheater; when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is higher than a first preset temperature, controlling to increase the flow of the flue gas entering the bypass cooling subsystem of the air preheater, and when the temperature of the flue gas at the side of the flue gas outlet of the air preheater is lower than the first preset temperature, controlling to decrease the flow of the flue gas entering the bypass cooling subsystem of the air preheater;
detecting a flue gas temperature at the first outlet side of the air preheater bypass cooling device; detecting a circulating oil temperature at the second inlet side of the recirculating cold smoke heating apparatus and a circulating oil temperature at the second outlet side of the recirculating cold smoke heating apparatus;
controlling the flow of the closed circulation oil pump according to the temperature of the flue gas on the first outlet side of the air preheater bypass cooling device; when the smoke temperature of the first outlet side of the air preheater bypass cooling device is higher than a second preset temperature, the temperature of circulating oil is maintained, the flow of the closed circulating oil pump is controlled to be increased, and when the smoke temperature of the first outlet side of the air preheater bypass cooling device is lower than the second preset temperature, the temperature of the circulating oil is maintained, and the flow of the closed circulating oil pump is controlled to be reduced.
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| CN101900347A (en) * | 2010-08-03 | 2010-12-01 | 山东泓奥电力科技有限公司 | System for high-grade recycling waste heat of smoke discharged from boiler of power station |
| CN102997262A (en) * | 2011-09-19 | 2013-03-27 | 上海康洪精密机械有限公司 | System for improving utilization grade of flue gas afterheat |
| CN102671538A (en) * | 2012-05-08 | 2012-09-19 | 浙江浙能节能科技有限公司 | Deep energy-saving system based on optimization of flue gas desulfurization and denitration technology |
| CN103411203A (en) * | 2013-05-24 | 2013-11-27 | 济南海普电力节能科技有限公司 | Method and device for carrying out gradient utilization on boiler flue gas waste heat to improve efficiency of thermal power unit |
| CN203431902U (en) * | 2013-06-28 | 2014-02-12 | 江西省电力设计院 | Smoke system reducing exhaust smoke temperature of secondary reheating boiler |
| CN209054550U (en) * | 2018-08-01 | 2019-07-02 | 中国电建集团江西省电力设计院有限公司 | Flue gas recirculation system |
| CN109059027A (en) * | 2018-08-27 | 2018-12-21 | 山东电力工程咨询院有限公司 | A kind of high-temperature biomass gas is cooling and the system and method for UTILIZATION OF VESIDUAL HEAT IN |
| CN109237505A (en) * | 2018-09-13 | 2019-01-18 | 华电电力科学研究院有限公司 | The device and its working method that water disappears white are received in a kind of classification waste heat recycling condensation of flue gas |
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