CN111609419A - Hot-cold circulating recycling system and method for flue gas water extraction - Google Patents
Hot-cold circulating recycling system and method for flue gas water extraction Download PDFInfo
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- CN111609419A CN111609419A CN202010538158.XA CN202010538158A CN111609419A CN 111609419 A CN111609419 A CN 111609419A CN 202010538158 A CN202010538158 A CN 202010538158A CN 111609419 A CN111609419 A CN 111609419A
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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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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
- B01D53/1481—Removing sulfur dioxide or sulfur trioxide
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L15/00—Heating of air supplied for combustion
- F23L15/04—Arrangements of recuperators
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B1/00—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser
- F28B1/02—Condensers in which the steam or vapour is separate from the cooling medium by walls, e.g. surface condenser using water or other liquid as the cooling medium
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28B—STEAM OR VAPOUR CONDENSERS
- F28B9/00—Auxiliary systems, arrangements, or devices
- F28B9/08—Auxiliary systems, arrangements, or devices for collecting and removing condensate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
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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
- Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery
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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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
Abstract
The invention discloses a hot-cold recycling system and a method for flue gas water lifting, and provides the hot-cold recycling system for flue gas water lifting, which is applied to boiler tail gas treatment and comprises a flue gas condensing subsystem and an air regenerative subsystem which are mutually communicated, wherein the flue gas condensing subsystem condenses and cools wet saturated flue gas after desulfurization equipment, the flue gas condensing subsystem transmits heat energy to the air regenerative subsystem, and the air regenerative subsystem performs low-order preheating on fresh air in an air inlet pipeline of a boiler; the hot-cold circulation recycling method for extracting water from flue gas comprises the steps of extracting moisture in wet saturated flue gas after a desulfurization process by adopting a condensation process, carrying out low-order preheating on fresh air in a pipeline at an air inlet of a boiler by utilizing high-temperature condensed mixed circulating water obtained by recycling, and cooling the circulating water at the same time. The hot and cold recycling system and method for flue gas water lifting ensure a cold source of flue gas water lifting, realize heat energy recycling and greatly reduce electric energy consumption.
Description
Technical Field
The invention relates to the technical field of boiler waste gas treatment, in particular to a hot-cold circulating recycling system and method for flue gas water extraction.
Background
In the technical field of boiler waste gas treatment, the purification treatment of conventional pollutants and unconventional pollutants is mainly carried out in the prior art at home and abroad, and the method is widely applied. Taking limestone-gypsum wet desulphurization as an example, flue gas generated by a boiler is discharged after passing through processing equipment such as an air preheater, an electric dust remover, an induced draft fan, a desulphurization absorption tower, a chimney and the like in sequence. Thermal power enterprises, chemical enterprises and metal smelting enterprises generally adopt a limestone-gypsum wet desulphurization technology to purify flue gas, the technology is mature and reliable, the desulphurization efficiency is generally over 90 percent, and most thermal power plants enable the emission concentration of sulfur dioxide to reach the ultra-low standard. On the other hand, water consumption of wet desulfurization has become an increasingly prominent problem; due to the technical characteristics, the high-temperature flue gas carries a large amount of saturated steam and liquid drops in the desulfurization treatment process, so that a large amount of water resource is consumed. Generally, the water consumption of wet desulphurization of a thermal power generating unit with a 600MW grade reaches 80 tons per hour, a large amount of external water sources must be used for supplementing water, and the water intake of two thermal power generating units with 600MW grades reaches 200 ten thousand tons per year. In water-poor areas, this water consumption is particularly contradictory to water scarcity.
The flue gas after desulfurization is purified and condensed, and the recovery of condensed water and waste heat is one of the leading-edge technologies of waste gas treatment, and is currently in the research and test stage. The prior tested new technology comprises a waste heat recovery device based on a heat pump technology, wherein the heat pump device is used for recovering the waste heat of the flue gas and supplying the waste heat to a heat supply network user, and meanwhile, part of condensed water can be generated in the flue gas condensation process. However, this technology mainly recovers waste heat, and the core technology is a heat pump technology, and condensed water is not sufficiently recovered.
In addition, the development direction is flue gas water extraction electricity-water cogeneration, a flue gas condensation water extraction system (patent publication No. CN106039755A), a cold source adopted is a conventional cooling tower, the electric energy consumption of a cooling fan of the device is high, exhausted heat discharged is dispersed into the atmospheric environment and cannot be fully utilized, and the main reason is that no heat supply network users are arranged around a power plant and the technical condition of utilizing the waste heat for supplying heat is not provided. For example, the heat dissipation power of a mechanical ventilation cooling tower in a certain project flue gas water lifting system reaches 50-60 MW. The heat is completely discharged into the atmospheric environment according to the conventional process, and a low-temperature refrigerant with enough low temperature can be obtained to ensure that the flue gas can be circularly cooled to generate condensed water; meanwhile, the forced ventilator of the cluster cooling tower also generates higher power consumption, and the power consumption cost of the forced ventilator accounts for 50% of the total cost of water lifting.
The technical problems to be solved are as follows: how to recycle the waste heat of the flue gas water-extracting cooling tower by using a new method? How to cancel the cooling fan and reduce the power consumption of the flue gas water-lifting cold source?
Therefore, how to provide a hot and cold recycling system for flue gas water extraction and a method thereof to solve the above-mentioned drawbacks is a technical problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
The invention aims to provide a hot and cold recycling system and method for flue gas water lifting, which realize the recycling of heat energy while ensuring a cold source for flue gas water lifting, and greatly reduce the consumption of electric energy.
In view of the above, the invention provides a hot and cold recycling system for flue gas water lifting, which is applied to boiler tail gas treatment, wherein a front end of the boiler tail gas treatment comprises wet desulphurization equipment, and the wet desulphurization equipment comprises a flue gas condensation subsystem and an air regenerative subsystem which are communicated with each other, the flue gas condensation subsystem condenses and cools wet saturated flue gas after the desulphurization equipment, the flue gas condensation subsystem transmits heat energy to the air regenerative subsystem, and the air regenerative subsystem performs low-order preheating on fresh air in an air inlet pipeline of a boiler.
The invention has the beneficial effects that: and the flue gas condensation subsystem arranged behind the desulfurization absorption tower is used for further purifying and recycling the desulfurized wet saturated flue gas to generate flue gas condensate water. In the treatment process, the flue gas is further purified, so that the concentration of smoke dust and the concentration of sulfur dioxide are further reduced, and the phenomenon that the desulfurized flue gas carries gypsum is thoroughly eliminated; the condensation water extraction of the flue gas treated by the wet desulphurization system is completed, a large amount of production water is provided, and water resources are remarkably saved. Through the air backheat subsystem carries out the low order to preheat the new trend of the air intake pipeline of a forced draught blower and secondary forced draught blower, further utilizes the flue gas waste heat heating input boiler's new trend, makes boiler efficiency obtain improving, utilizes the convulsions of a forced draught blower and secondary forced draught blower to cool off cycle fluid simultaneously, has avoided the setting of ventilation cooling tower, has reduced cooling fan's for the cooling tower electric energy consumption. The hot and cold recycling system for flue gas water lifting realizes the recycling of heat energy while ensuring a cold source of flue gas water lifting, and greatly reduces the consumption of electric energy.
Further, the flue gas condensation subsystem includes inflation water storage box, flue gas condensation tower and condensation circulating pump, the air backheat subsystem is including setting up low order fan heater on the boiler intake stack, the delivery port of inflation water storage box communicates through the pipeline low order fan heater, the delivery port of low order fan heater passes through the pipeline intercommunication the water inlet of condensation circulating pump, the condensation circulating pump is squeezed into cold water the spray set at flue gas condensation tower top, flue gas condensation tower bottom is provided with the wet return, the wet return communicates the inflation water storage box.
Further, still include the air heater of primary air second order, overgrate air second order air heater and cigarette cold ware, air heater of primary air second order and overgrate air second order air heater set up respectively on the primary air and the overgrate air pipeline of boiler intake stack, the cigarette cold ware sets up on the flue gas pipeline between air heater and electrostatic precipitator, air heater of primary air second order, overgrate air second order air heater and cigarette cold ware are linked together through endless heat-conducting medium.
Preferably, the heat-conducting medium specifically adopts low-hardness pure water, and the low-hardness pure water is driven by a circulating pump to circularly flow among the primary air second-order air heater, the secondary air second-order air heater and the smoke cooler.
And further, the system also comprises a ventilation cooling tower, wherein the ventilation cooling tower is connected with the low-order air heater in parallel through a bypass pipeline and is communicated to the condensation circulating water pipeline.
A hot-cold circulation recycling method for flue gas water extraction is applied to boiler tail gas treatment and comprises the steps of extracting moisture in wet saturated flue gas after a desulfurization process by adopting a condensation process, carrying out low-order preheating on fresh air in a boiler air inlet pipeline by utilizing high-temperature condensation mixed circulating water obtained by recycling, and cooling the circulating water.
The hot and cold recycling method for flue gas water extraction utilizes the heat energy conversion of the condensation process and the low-order preheating process, realizes the recycling of heat energy while ensuring the work of flue gas condensation water extraction, and greatly reduces the power consumption.
Furthermore, the temperature of the wet saturated flue gas after the desulfurization process is adjusted to be 43-55 ℃, the condensation process works by adopting a mixed heat exchange principle, and the mixed heat exchange temperature of the condensation process is reduced by 3-8 ℃ relative to the dew point of water vapor.
Preferably, the space heat exchange coefficient of the condensation process is 3401.3W/m3℃～14067.3W/m3℃。
Preferably, the temperature of the circulating water used in the condensation process is 26-42 ℃, the temperature of the circulating water used in the low-order preheating process is 8-38 ℃, and the temperature difference between the circulating water used in the condensation process and the circulating water used in the low-order preheating process is 4-18 ℃.
Drawings
In order to more clearly illustrate the embodiments of the present invention 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 embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a hot and cold recycling system for flue gas water extraction according to an embodiment 1 of the present invention;
FIG. 2 is a schematic structural diagram of the hot and cold recycling system for flue gas water extraction according to embodiment 2 of the present invention;
FIG. 3 is a schematic diagram of the low-order heat regeneration principle of the present invention;
FIG. 4 is a schematic diagram of the second-order regenerative principle of the present invention;
fig. 5 is a schematic structural diagram of the low-order air heater of the present invention.
The system comprises a boiler 1, a coal mill 2, an air preheater 3, an electric dust remover 4, an induced draft fan 5, a desulfurization absorption tower 6, a chimney 7, a primary air blower 8, a secondary air blower 9, an expansion water storage tank 10, a flue gas condensation tower 11, a condensation circulating pump 12, a low-order air heater 13, a first flow guide cover 1301, a second flow guide cover 1302, a primary air second-order air heater 14, a secondary air second-order air heater 15, a flue gas cooler 16 and a ventilation cooling tower 17.
Detailed Description
The core of the invention is to provide a hot and cold recycling system and a method for flue gas water lifting, which realize the recycling of heat energy while ensuring a cold source for flue gas water lifting, and greatly reduce the consumption of electric energy.
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.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Referring to the attached drawings, fig. 1 is a schematic structural diagram of a hot and cold circulation recycling system for flue gas water extraction according to an embodiment 1 of the invention; FIG. 2 is a schematic structural diagram of the hot and cold recycling system for flue gas water extraction according to embodiment 2 of the present invention; FIG. 3 is a schematic diagram of the low-order heat regeneration principle of the present invention; FIG. 4 is a schematic diagram of the second-order regenerative principle of the present invention; fig. 5 is a schematic structural diagram of the low-order air heater of the present invention.
In embodiment 1, as shown in fig. 1, 3, and 4, a hot-cold circulation recycling system for flue gas water extraction is applied to the field of boiler tail gas treatment, a front end of the boiler tail gas treatment comprises a wet desulfurization device, in a mature limestone-gypsum wet desulfurization process, flue gas generated by a boiler 1 sequentially passes through treatment devices such as an air preheater 3, an electric dust remover 4, an induced draft fan 5, a desulfurization absorption tower 6, a chimney 7, and the like, and is discharged, a primary air feeder 8 and a secondary air feeder 9 blow fresh air into the boiler 1 to support combustion, and primary air of the primary air feeder 8 carries pulverized coal generated by a coal mill 2 to enter a combustion chamber of the boiler 1. The hot-cold circulation recycling system for flue gas water lifting comprises a flue gas condensation subsystem and an air regenerative subsystem which are communicated with each other, wherein the flue gas condensation subsystem is arranged behind a desulfurization absorption tower 6 and condenses and cools wet saturated flue gas, the flue gas condensation subsystem transmits heat energy to the air regenerative subsystem, and the air regenerative subsystem carries out low-order preheating on fresh air in air inlet pipelines of a primary air feeder 8 and a secondary air feeder 9.
The flue gas condensation subsystem arranged behind the desulfurization absorption tower 6 is used for further purifying and recycling the desulfurized wet saturated flue gas to generate flue gas condensate water. In the treatment process, the flue gas is further purified, so that the concentration of smoke dust and the concentration of sulfur dioxide are further reduced, and the phenomenon that the desulfurized flue gas carries gypsum is thoroughly eliminated; the condensation water extraction of the flue gas treated by the wet desulphurization system is completed, a large amount of production water is provided, and water resources are remarkably saved. Through the air backheat subsystem carries out the low order to the new trend of the air intake pipeline of blower 8 and secondary air feeder 9 and preheats, further utilizes the flue gas waste heat to heat the new trend of input boiler, makes boiler efficiency obtain improving, utilizes the convulsions of blower 8 and secondary air feeder 9 to cool down to cycle fluid simultaneously, has avoided the setting of ventilation cooling tower, has reduced cooling fan's for the cooling tower electric energy consumption. The hot and cold recycling system for flue gas water lifting realizes the recycling of heat energy while ensuring a cold source of flue gas water lifting, and greatly reduces the consumption of electric energy.
In a specific embodiment of this embodiment, as shown in fig. 1, the flue gas condensation subsystem includes inflation water storage tank 10, flue gas condensing tower 11 and condensation circulating pump 12, the air backheat subsystem is including setting up low order fan heater 13 on primary air feeder 8 and secondary air feeder 9 air-supply line, and the delivery port of inflation water storage tank 10 communicates the inside heating coil water inlet of low order fan heater 13 through the pipeline, and the heating coil delivery port of low order fan heater 13 passes through the water inlet of pipeline intercommunication condensation circulating pump 12, and condensation circulating pump 12 squeezes cold water into the spray set at 11 tops of flue gas condensing tower, and 11 bottoms of flue gas condensing tower are provided with the wet return, the wet return communicates inflation water storage tank 10.
Specifically, as shown in fig. 5, the low-order air heater 13 specifically uses a dividing wall type heat exchanger for heat exchange, a water outlet side box body of the dividing wall type heat exchanger is provided with a water outlet, and a water inlet side box body of the dividing wall type heat exchanger is provided with a water inlet. The air inlet side of the low-order air heater 13 is provided with a rainproof first air guide sleeve 1301, and the air outlet side is provided with a second air guide sleeve 1302 communicated with an air pipe. Of course, the low-stage air heater 13 in the present invention may also adopt a mixed-flow type heat exchanger. Similar variations fall within the scope of the invention.
Through the circulation loop of the circulating water working medium of expansion water storage tank 10, flue gas condensing tower 11, condensation circulating pump 12 and low order fan heater 13 cooperation pipeline intercommunication, form low order backheat circulation, the new trend of transmission heat energy heating boiler when being convenient for accomplish the work of lifting water.
In a specific embodiment of this embodiment, as shown in fig. 1, the desulfurization device specifically employs a desulfurization absorption tower 6, and the desulfurization absorption tower 6 and the flue gas condensation tower 11 are stacked to form a desulfurization and water-lifting integrated structure.
Through the setting of desulfurization water lift integrated configuration, be convenient for shorten the flow stroke of wet saturated flue gas after the desulfurization, reduce the temperature loss, be convenient for high-efficient condensation water lift smoothly.
In a specific implementation manner of this embodiment, as shown in fig. 1 and fig. 4, the system further includes a primary air second-order air heater 14, a secondary air second-order air heater 15, and a smoke cooler 16, where the primary air second-order air heater 14 and the secondary air second-order air heater 15 are respectively disposed on a primary air pipeline and a secondary air pipeline of an air inlet pipeline of the boiler, the smoke cooler 16 is disposed on a smoke pipeline between the air preheater 3 and the electric precipitator 4, and the primary air second-order air heater 14, the secondary air second-order air heater 15, and the smoke cooler 16 are communicated with each other through a circulating heat conducting medium.
Specifically, the primary air second-order air heater 14 and the secondary air second-order air heater 15 are finned tube dividing wall type heat exchangers.
Specifically, the heat-conducting medium is low-hardness pure water, and the low-hardness pure water is driven by a circulating pump to circularly flow among the primary air second-order air heater 14, the secondary air second-order air heater 15 and the smoke cooler 16.
Through the second-order regenerative cycle that primary air second-order air heater 14, overgrate air second-order air heater 15 and cigarette cold ware 16 are constituteed, can make the pre-cooling of boiler exhaust flue gas, retrieve the flue gas waste heat simultaneously and further heat the air, improve boiler efficiency.
In a specific embodiment of this embodiment, the temperature of flue gas discharged by a 660MW thermal power generating unit lignite boiler after combustion is 142 ℃, the flue gas enters a flue gas condensing tower 11 after being subjected to denitration, dedusting and desulfurization treatment, at this time, the temperature of wet saturated flue gas after flue gas desulfurization is 55 ℃, the wet saturated flue gas is mixed with condensing circulating water for heat exchange, the temperature of the flue gas is reduced to 48 ℃, and the generation amount of flue gas condensate water is 96 tons/hour; in the process, the circulating water is heated by the flue gas in the flue gas condensing tower 11, and the temperature of the circulating water is increased from 36 ℃ to 47 ℃.
In the cold section of the flue gas hot-cold circulation, a two-stage regenerative heating process is generated. In the low-order regenerative cycle, the fresh air at the inlet of the fan of the boiler is heated by the low-order circulating water, the process is carried out in the low-order air heater 13, the temperature of the circulating water at the inlet is 47 ℃, and the temperature is reduced to 36 ℃ after the air is heated; the fresh air is heated from 26 ℃ to 38 ℃.
In the second-order regenerative cycle, heat exchange is carried out through independent second-order circulating water, the flue gas discharged by boiler combustion firstly heats the second-order circulating water in the flue gas cooler 16, the temperature of the flue gas is reduced from 142 ℃ to 105 ℃, and meanwhile, the second-order circulating water is heated from 74 ℃ to 95 ℃; the circulating water respectively heats air in the primary air second-order air heater 14 and the secondary air second-order air heater 15, so that the temperature of the air is further increased to 69 ℃ from 38 ℃, and meanwhile, the temperature of the second-order circulating water is reduced to 73 ℃ from 95 ℃.
In the flue gas hot-cold cycle, the flue gas respectively passes through two-stage regenerative heating processes in the flue gas condensing tower in front of the desulfurizing tower and in the flue gas condensing tower after desulfurization, and two hot-cold cycles are completed. Wherein the low order backheating circulation is the main cycle, produces 96 tons of flue gas condensate water per hour in this circulative cooling flue gas process, heats the new trend of boiler fan entry simultaneously, retrieves heat energy power and reaches 55 MW. The second-order regenerative cycle is an auxiliary cycle and has the functions of pre-cooling the flue gas discharged by the boiler and simultaneously recovering the waste heat of the flue gas to further heat the air.
In embodiment 2, the present embodiment is formed by adding a ventilation cooling tower 17 to embodiment 1, and the ventilation cooling tower 17 is connected in parallel with the low-stage air heater 13 through a bypass pipeline and communicated to the condensation circulating water pipeline. This is a peak shaving device set for extreme hot season conditions. In the above embodiment 1, when the ambient temperature is higher than 38 ℃, the original low-order hot-cold circulation loop has reached the marginal heat exchange working condition, the cold source provided at the air side of the boiler inlet is not enough to condense the flue gas sufficiently, at this time, the valve on the bypass pipeline is opened, the ventilation cooling tower 17 is put into operation, the temperature of the circulating water is further reduced by 3 ℃ to 5 ℃, the lower heat exchange temperature can still be maintained in the flue gas condensation tower 11, the continuous generation of flue gas condensate water is kept, and the smooth operation of water lifting is ensured.
The invention also provides a hot-cold circulation recycling method for flue gas water extraction, which is applied to the treatment of boiler tail gas and comprises the steps of extracting moisture in wet saturated flue gas after a desulfurization process by adopting a condensation process, carrying out low-order preheating on fresh air in an air inlet pipeline of a boiler by utilizing high-temperature condensation mixed circulating water obtained by recycling, and cooling the circulating water. The hot and cold recycling method for flue gas water extraction utilizes the heat energy conversion of the condensation process and the low-order preheating process, realizes the recycling of heat energy while ensuring the work of flue gas condensation water extraction, and greatly reduces the power consumption.
Specifically, the temperature of the wet saturated flue gas after the desulfurization process is adjusted to be 43-55 ℃, the condensation process works by adopting a hybrid heat exchange principle, and the hybrid heat exchange temperature of the condensation process is reduced by 3-8 ℃ relative to the dew point of water vapor. The condensation water-extracting efficiency can be greatly improved by adjusting the temperature within a proper range.
Specifically, the space heat exchange coefficient of the condensation tower in the condensation process is 3401.3W/m3 ℃E
14067.3W/m3 ℃. In the condensation process, the temperature difference between the wet saturated flue gas at the inlet of the condensation tower and the condensed water temperature of the flue gas flowing out is 5-7 ℃, and the temperature difference between the flue gas at the outlet of the condensation tower and the cooling circulating water sprayed into the condensation tower is 5-12 ℃. The water production capacity of the condensing tower in the condensation process of the hot and cold circulation recycling method for flue gas water extraction is 0.133 t/MWh-0.31 t/MWh for the power station boiler.
Specifically, the temperature of circulating water used in the condensation process is 26-42 ℃, the temperature of circulating water used in the low-order preheating process is 8-38 ℃, and the temperature difference of circulating water used in the condensation process and the low-order preheating process is 4-18 ℃.
The water temperature and the temperature difference of circulating water are kept in the range through a condensation process and a low-order preheating process, so that the low-order heat regeneration circulation is smoothly performed, and the water lifting efficiency can be ensured.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. The utility model provides a hot cold circulation recycling system of flue gas lift water, uses in boiler tail gas handles, and boiler tail gas handles the front end and includes wet flue gas desulfurization equipment, its characterized in that, including flue gas condensation subsystem and the air backheat subsystem that communicates each other, the wet saturation flue gas behind the flue gas condensation subsystem to desulfurization equipment condenses and cools down, flue gas condensation subsystem transmits heat energy for the air backheat subsystem, the air backheat subsystem is right the new trend of boiler air intake pipeline carries out the low order and preheats.
2. The hot and cold recycling system of flue gas water lifting according to claim 1, wherein the flue gas condensing subsystem comprises an expansion water storage tank (10), a flue gas condensing tower (11) and a condensing circulating pump (12), the air heat recovery subsystem comprises a low-order air heater (13) arranged on an air inlet pipeline of the boiler, a water outlet of the expansion water storage tank (10) is communicated to the low-order air heater (13) through a pipeline, a water outlet of the low-order air heater (13) is communicated to a water inlet of the condensing circulating pump (12) through a pipeline, the condensing circulating pump (12) pumps cold water into a spraying device at the top of the flue gas condensing tower (11), a water return pipe is arranged at the bottom of the flue gas condensing tower (11), and the water return pipe is communicated to the expansion water storage tank (10).
3. The hot-cold recycling system for flue gas water lifting according to claim 2, further comprising a primary air second-order air heater (14), a secondary air second-order air heater (15) and a flue gas cooler (16), wherein the primary air second-order air heater (14) and the secondary air second-order air heater (15) are respectively arranged on a primary air pipeline and a secondary air pipeline of the boiler air inlet pipeline, the flue gas cooler (16) is arranged on a high-temperature flue gas pipeline in front of the desulfurization device, and the primary air second-order air heater (14), the secondary air second-order air heater (15) and the flue gas cooler (16) are communicated through a circulating heat conducting medium.
4. The heat and cold recycling system for flue gas water lifting according to claim 3, wherein the heat conducting medium is low hardness pure water, and the low hardness pure water is driven by a circulating pump to circularly flow among the primary air second-order air heater (14), the secondary air second-order air heater (15) and the flue gas cooler (16).
5. The hot and cold recycling system for the flue gas water lifting according to any one of claims 2 to 4, further comprising a ventilation cooling tower (17), wherein the ventilation cooling tower (17) is connected in parallel with the low-order air heater (13) through a bypass pipeline and is communicated to a condensation circulating water pipeline.
6. A hot-cold circulation recycling method for flue gas water extraction is applied to boiler tail gas treatment and is characterized by comprising the steps of extracting moisture in wet saturated flue gas after a desulfurization process by adopting a condensation process, carrying out low-order preheating on fresh air in a boiler air inlet pipeline by utilizing high-temperature condensation mixed circulating water obtained by recycling, and cooling the circulating water.
7. The heat-cold cycle recycling method of flue gas water extraction according to claim 6, wherein the temperature of the wet saturated flue gas after the desulfurization process is adjusted to 43 ℃ to 55 ℃, the condensation process works by adopting a mixed heat exchange principle, and the mixed heat exchange temperature of the condensation process is reduced by 3 ℃ to 8 ℃ relative to the dew point of water vapor.
8. The method for recycling the heat and cold circulation of the flue gas water extraction according to claim 7, wherein the space heat exchange coefficient of the condensation process is 3401.3W/m3℃～14067.3W/m3℃。
9. The method for recycling the heat and cold of the flue gas water extraction according to claim 8, wherein the temperature of the circulating water used in the condensation process is 26-42 ℃, the temperature of the circulating water used in the low-order preheating process is 8-38 ℃, and the temperature difference between the circulating water used in the condensation process and the circulating water used in the low-order preheating process is 4-18 ℃.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113713599A (en) * | 2021-09-10 | 2021-11-30 | 国能神东煤炭集团有限责任公司 | Circulating fluidized bed semi-dry method low-load desulfurization system and control method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113713599A (en) * | 2021-09-10 | 2021-11-30 | 国能神东煤炭集团有限责任公司 | Circulating fluidized bed semi-dry method low-load desulfurization system and control method |
| CN113713599B (en) * | 2021-09-10 | 2023-05-12 | 国能神东煤炭集团有限责任公司 | Semi-dry low-load desulfurization system of circulating fluidized bed and control method |
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