CN112607944A - Coal-fired power plant desulfurization wastewater treatment system and method based on flue gas cooperative treatment - Google Patents
Coal-fired power plant desulfurization wastewater treatment system and method based on flue gas cooperative treatment Download PDFInfo
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- 239000003546 flue gas Substances 0.000 title claims abstract description 89
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 87
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 77
- 230000023556 desulfurization Effects 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000004065 wastewater treatment Methods 0.000 title claims abstract description 18
- 239000002351 wastewater Substances 0.000 claims abstract description 60
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 60
- 238000001035 drying Methods 0.000 claims abstract description 58
- 239000000428 dust Substances 0.000 claims abstract description 35
- 238000001704 evaporation Methods 0.000 claims abstract description 35
- 230000008020 evaporation Effects 0.000 claims abstract description 34
- 239000010881 fly ash Substances 0.000 claims abstract description 32
- 230000003009 desulfurizing effect Effects 0.000 claims abstract description 15
- 208000028659 discharge Diseases 0.000 claims description 8
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000002956 ash Substances 0.000 abstract description 4
- 239000003344 environmental pollutant Substances 0.000 abstract description 4
- 231100000719 pollutant Toxicity 0.000 abstract description 4
- 239000000243 solution Substances 0.000 description 23
- 238000005516 engineering process Methods 0.000 description 10
- 238000002425 crystallisation Methods 0.000 description 9
- 230000008901 benefit Effects 0.000 description 8
- 230000008025 crystallization Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000012528 membrane Substances 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000009388 chemical precipitation Methods 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010440 gypsum Substances 0.000 description 1
- 229910052602 gypsum Inorganic materials 0.000 description 1
- 239000008236 heating water Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
- C02F1/16—Treatment of water, waste water, or sewage by heating by distillation or evaporation using waste heat from other processes
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
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- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
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- Treating Waste Gases (AREA)
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Abstract
The invention discloses a coal-fired power plant desulfurization wastewater treatment system and a method based on flue gas cooperative treatment, wherein the system comprises a boiler, a denitration reactor, an air preheater, a flue gas cooler, a dust remover, an induced draft fan and a desulfurization tower which are sequentially communicated along the flow direction of flue gas; a desulfurization waste water outlet of the desulfurization tower is sequentially communicated with a multi-effect flash evaporation concentrator and a drying tower, and a pH value adjusting port is arranged on the path from the desulfurization tower to the multi-effect flash evaporation concentrator; a concentrated solution outlet of the multi-effect flash evaporation concentrator is communicated with the drying tower, and a water vapor outlet of the multi-effect flash evaporation concentrator is communicated with the desulfurizing tower; the working medium inlet of the drying tower is communicated with the flue gas outlet of the denitration reactor, the outlet of the drying tower is communicated with the dust remover, the desulfurization wastewater is concentrated while the flue gas temperature is reduced and pollutants are cooperatively treated, the water vapor generated by treating the concentrated solution by adopting high-temperature flue gas is directly conveyed to the desulfurization tower system, the crystallized fly ash is reinjected to the front flue of the dust remover and finally recycled along with ash residues of the dust remover, and the zero discharge of the desulfurization wastewater is realized.
Description
Technical Field
The invention belongs to the technical field of energy, chemical industry and environmental protection, and particularly relates to a coal-fired power plant desulfurization wastewater treatment system and method based on flue gas cooperative treatment.
Background
The flue gas cooperative treatment technology is used for treating pollutant emission to the maximum extent through the cooperative treatment capability of equipment under the condition that an original flue gas system is not changed. The most widely applied cooperative treatment technology in the prior art is a cooperative treatment technology taking a low-temperature dust remover as a core, and the principle of the cooperative treatment technology is that the flue gas temperature at the inlet of the dust remover is reduced, SO that the electrostatic dust removal efficiency is improved and the SO is generated at the same time3And pollutants such as Hg and the like are separated out and adsorbed on the fly ash, and are finally collected and discharged by a dust collector along with the fly ash. Therefore, in most coal power plants, an eye-maker cooling device is additionally arranged between the air preheater and the dust remover. After the temperature of the flue gas is reduced, the part of heat energy can be used for heating water supply, raising the temperature of the flue gas and the like after being collected, certain economic benefit is brought to a power plant, and the part of heat energy is used for a desulfurization system and is not implemented.
The wet desulfurizing technology is mainly adopted in coal-fired power stations and other coal-fired boilers, and the technology is characterized in that limestone/lime slurry and SO in coal-fired flue gas2Reacting to form gypsum (CaSO)4) Thereby reducing SO2And (4) discharging. The process has the advantages of mature technology, high desulfurization efficiency, simple operation, low operation cost and wide applicable coal quality; the disadvantage is that after desulfurization, part of the waste water is produced. With the continuous improvement of environmental standards, the problem of discharging desulfurization wastewater is gradually paid more attention, and some regions clearly require enterprises to reduce desulfurization wastewater and even realize zero discharge in factories.
The desulfurization wastewater zero-discharge technology generally comprises a chemical precipitation method, a membrane concentration method, evaporative crystallization, a flue injection method and the like. Wherein, the chemical precipitation method can generate secondary pollutants such as sludge, secondary waste liquid and the like, and the disposal cost is high. The membrane concentration method has higher automation degree, but the membrane is easy to be polluted and blocked and needs to be replaced regularly, so the operation cost is high and the popularization is difficult; the evaporative crystallization method consumes a large amount of heat, and the crystallized crystals have many impurities and are difficult to recycle, so that the problems of difficult stacking and difficult disposal exist; the flue injection method can better evaporate the desulfurization waste water into fine particles and mix the fine particles with smashed smoke dust, and the fine particles are finally recycled along with fly ash, but the continuous spraying of the desulfurization waste water into a flue gas air system can cause the continuous increase of the humidity of flue gas, so that equipment corrosion is easily caused finally, and the operation safety of the system is threatened.
In conclusion, the existing desulfurization wastewater zero-discharge treatment technology has advantages and disadvantages, and the economical efficiency, safety and environmental protection can not be fully considered. Therefore, it is urgent to find a safe, efficient and inexpensive zero-discharge process for desulfurization waste water.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a coal-fired power plant desulfurization wastewater treatment system and method based on flue gas cooperative treatment, which realize zero emission treatment of desulfurization wastewater, perform gradient utilization on flue gas heat, fully utilize the existing equipment and reduce the wastewater treatment cost.
In order to achieve the purpose, the invention adopts a coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment, which comprises a boiler, a denitration reactor, an air preheater, a flue gas cooler, a dust remover, an induced draft fan and a desulfurization tower which are sequentially communicated along the flow direction of flue gas; a desulfurization waste water outlet of the desulfurization tower is sequentially communicated with a multi-effect flash evaporation concentrator and a drying tower, and a pH value adjusting port is arranged on the path from the desulfurization tower to the multi-effect flash evaporation concentrator; a concentrated solution outlet of the multi-effect flash evaporation concentrator is communicated with an inlet of the drying tower, and a water vapor outlet of the multi-effect flash evaporation concentrator is communicated with the desulfurizing tower; the working medium inlet of the drying tower is communicated with the flue gas outlet of the denitration reactor, and the outlet of the drying tower is communicated with the dust remover.
A wastewater delivery pump is arranged on the path from the desulfurizing tower to the multi-effect flash evaporator; a concentrated solution delivery pump is arranged between a concentrated solution outlet of the multi-effect flash evaporation concentrator and an inlet of the drying tower; a condensed water circulating pump is arranged between the condensed water outlet and the inlet of the flue gas cooler; a crystallizing fly ash conveying pump is arranged between the outlet of the drying tower and the inlet of the dust remover.
The flue at the outlet of the denitration reactor is divided into two paths, wherein one path of flue is communicated with the air preheater, and the other path of flue is communicated with the drying tower.
A concentrated heat source inlet of the multi-effect flash evaporation concentrator is communicated with an outlet of the flue gas cooler, and a condensed water outlet of the multi-effect flash evaporation concentrator is communicated with an inlet of the flue gas cooler; the multi-effect flash evaporator comprises a flash evaporation tank and a heater, the bottom of the flash evaporation tank is communicated with the bottom of the heater, the top end of the heater is introduced into the upper part of the flash evaporation tank, and the bottom of the flash evaporation tank is provided with a concentrated solution circulating pump; the top of the heater is provided with a wastewater inlet communicated with a desulfurization wastewater inlet, and the middle of the heater is provided with a heat medium inlet communicated with a concentrated heat source inlet; the lower part of the heater is provided with a condensed water outlet which is communicated with a condensed water outlet.
The multiple-effect flash evaporation concentrator is provided with a plurality of, refer to a plurality of multiple-effect flash evaporation concentrators along the medium flow direction: the heat medium outlet of the upstream multi-effect flash concentrator is communicated with the heat medium inlet of the downstream multi-effect flash concentrator; the waste water outlet of the upstream direction multi-effect flash evaporation concentrator is communicated with the waste water inlet of the downstream direction multi-effect flash evaporation concentrator, the heat medium outlet of the tail end multi-effect flash evaporation concentrator is communicated with the desulfurizing tower through the water vapor outlet, the waste water outlet of the tail end multi-effect flash evaporation concentrator is communicated with the drying tower through the concentrated solution outlet, the heat medium inlet of the start end multi-effect flash evaporation concentrator is communicated with the outlet of the flue gas cooler, and the circulating water outlet of each multi-effect flash evaporation concentrator is communicated with the inlet of the flue gas cooler through the condensed water outlet.
The drying tower adopts a vertical type, a horizontal type or a rotary type.
And a cooling device or a flow regulating valve is arranged on the path from the drying tower to the dust remover.
The invention also provides a coal-fired power plant desulfurization wastewater zero-discharge treatment method based on flue gas cooperative treatment, the pH value of the desulfurization wastewater is adjusted to 7-8, then the desulfurization wastewater is concentrated and evaporated, and water vapor is directly discharged to a flue; drying the concentrated solution to form crystallized fly ash, and recovering and treating the crystallized fly ash; high-temperature flue gas is used as a heat source for drying concentrated solution and an auxiliary conveying crystallization fly ash gas source.
The heat source of the concentrated evaporative desulfurization wastewater comes from high-temperature water heated by the flue gas cooler, the high-temperature water is condensed into condensed water after working, and the condensed water enters the flue gas cooler for heating circulation.
And conveying the crystallized fly ash to a flue before an inlet of a dust remover, wherein when the crystallized fly ash is reinjected to the flue, the reinjection temperature of the crystallized fly ash is the same as the temperature of the original smoke in the flue.
Compared with the prior art, the invention has at least the following beneficial effects: 1. the concentration system adopting hot water circulation fully utilizes the heat collected by cooling the flue gas, reduces the temperature of the flue gas and realizes the concentration of the desulfurization wastewater.
2. The drying and conveying system based on high-temperature flue gas has the advantages of being fast in concentration and drying, large in treatment capacity, small in equipment size and the like.
3. The concentrated part of water vapor is directly discharged to the desulfurizing tower for recycling, and the make-up water of a desulfurizing system is reduced.
4. According to the invention, the pH value adjusting port is additionally arranged before the concentration of the desulfurization wastewater, so that the generation of acidic gas in the concentration and drying processes can be greatly reduced, and the risks of equipment corrosion and waste gas emission are further reduced.
5. All the treated crystallized fly ash is reinjected to the dust remover and finally stacked and recycled together with ash of the dust remover, thereby fundamentally solving the problem of zero emission of waste.
6. The system has the advantages of simple equipment, mature technology, high integration degree, low investment and good economical efficiency, and utilizes the original flue gas treatment equipment of the coal-fired boiler to the maximum extent.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention.
Figure 2 is a schematic diagram of a multi-effect flash concentration system.
FIG. 3 is a schematic view of a conventional desulfurization waste water disposal system.
In the figure: 1-boiler, 2-denitration reactor, 3-air preheater, 4-flue gas cooler, 5-dust remover, 6-induced draft fan, 7-desulfurizing tower, 8-chimney, 9-multiple-effect flash evaporator concentrator, 10-drying tower, 11-pH value adjusting port, 12-condensed water, 13-high temperature water, 14-flue gas, 15-crystallization wastewater, 16-wastewater delivery pump, 17-concentrated solution delivery pump, 18-condensed water delivery pump, 19-crystallization fly ash delivery pump, 9.1-flash tank, 9.2-heater, 9.3-concentrated solution circulating pump, 9.4-concentrated heat source inlet, 9.5-desulfurization wastewater inlet, 9.6-water vapor outlet, 9.7-concentrated solution outlet and 9.8-condensed water outlet.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings, but they are not to be construed as limiting the invention, and are merely illustrative, and the advantages of the invention will be more clearly understood and appreciated by those skilled in the art.
Referring to fig. 1, a coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment comprises a boiler 1, a denitration reactor 2, an air preheater 3, a flue gas cooler 4, a dust remover 5, an induced draft fan 6 and a desulfurization tower 7 which are sequentially communicated along the flow direction of flue gas; a desulfurization waste water outlet of the desulfurization tower 7 is sequentially communicated with a multi-effect flash evaporator concentrator 9 and a drying tower 10, and a pH value adjusting port 11 is arranged on the path from the desulfurization tower 7 to the multi-effect flash evaporator concentrator 9; a concentrated solution outlet 9.7 of the multi-effect flash evaporator concentrator 9 is communicated with an inlet of the drying tower 10, and a water vapor outlet 9.6 of the multi-effect flash evaporator concentrator 9 is communicated with the desulfurizing tower 7; the working medium inlet of the drying tower 10 is communicated with the flue gas outlet of the denitration reactor 2, and the outlet of the drying tower 10 is communicated with the dust remover 5.
A waste water delivery pump 16 is arranged on the path from the desulfurizing tower 7 to the efficient flash concentrator 9; a concentrated solution delivery pump 17 is arranged between a concentrated solution outlet 9.7 of the multi-effect flash evaporator concentrator 9 and an inlet of the drying tower 10; a condensed water circulating pump 18 is arranged between the condensed water outlet 9.8 and the inlet of the flue gas cooler 4; a crystallizing fly ash conveying pump 19 is arranged between the outlet of the drying tower 10 and the inlet of the dust remover 5.
The flue at the outlet of the denitration reactor 2 is divided into two paths, wherein one path of flue is communicated with the air preheater 3, and the other path of flue is communicated with the drying tower 10.
Referring to FIG. 1: the invention relates to a coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment, which comprises a boiler 1, a denitration reactor 2, an air preheater 3, a flue gas cooler 4, a dust remover 5, an induced draft fan 6, a desulfurization tower 7, a chimney 8, a multi-effect flash evaporation concentrator 9, a drying tower 10, a pH value adjusting port 11, condensed water 12, hot water 13, high-temperature flue gas 14 crystallization fly ash 15, a wastewater delivery pump 16, a concentrated solution delivery pump 17, a condensed water circulating pump 18 and a crystallization fly ash delivery pump 19; the multi-effect flash evaporator 9 comprises a flash evaporation tank 9.1, a heater 9.2, a concentrated solution circulating pump 9.3, a concentrated heat source inlet 9.4, a concentrated wastewater inlet 9.5, a water vapor outlet 9.6, a concentrated solution outlet 9.7 and a condensed water outlet 9.8; the boiler 1, the denitration reactor 2, the air preheater 3, the flue gas cooler 4, the dust remover 5, the induced draft fan 6, the desulfurizing tower 7 and the chimney 8 are connected in sequence through a flue; the flue gas of the denitration reactor 2 is divided into two parts at the outlet, one part is connected with the air preheater 3 through a flue, and the other part 14 is connected with the drying tower 10; the bottom of the drying tower 10 is provided with a crystallization fly ash outlet which is connected with the crystallization fly ash delivery pump 19 through a pipeline and is finally connected to a flue between the flue gas cooler 4 and the dust remover 5.
A desulfurization waste water outlet of the desulfurization tower 7 is sequentially communicated with a multi-effect flash evaporator concentrator 9 and a drying tower 10, and a pH value adjusting port 11 is arranged on the path from the desulfurization tower 7 to the multi-effect flash evaporator concentrator 9; a concentrated solution outlet 9.7 of the multi-effect flash evaporator concentrator 9 is communicated with an inlet of the drying tower 10, and a water vapor outlet 9.6 of the multi-effect flash evaporator concentrator 9 is communicated with the desulfurizing tower 7; the working medium inlet of the drying tower 10 is communicated with the flue gas outlet of the denitration reactor 2, and the outlet of the drying tower 10 is communicated with the dust remover 5.
A waste water delivery pump 16 is arranged on the path from the desulfurizing tower 7 to the efficient flash concentrator 9; a concentrated solution delivery pump 17 is arranged between a concentrated solution outlet 9.7 of the multi-effect flash evaporator concentrator 9 and an inlet of the drying tower 10; a condensed water circulating pump 18 is arranged between the condensed water outlet 9.8 and the inlet of the flue gas cooler 4; a crystallizing fly ash conveying pump 19 is arranged between the outlet of the drying tower 10 and the inlet of the dust remover 5.
Referring to fig. 1 and 2: a concentrated heat source inlet 9.4 of the multi-effect flash evaporator 9 is communicated with an outlet of the flue gas cooler 4, and a condensed water outlet 9.8 of the multi-effect flash evaporator 9 is communicated with an inlet of the flue gas cooler 4; the multi-effect flash evaporator concentrator 9 comprises a flash evaporation tank 9.1 and a heater 9.2, the bottom of the flash evaporation tank 9.1 is communicated with the bottom of the heater 9.2, the top end of the heater 9.2 is introduced into the upper part of the flash evaporation tank 9.1, and a concentrated solution circulating pump 9.3 is arranged at the bottom of the flash evaporation tank 9.1; a wastewater inlet communicated with a desulfurization wastewater inlet 9.5 is formed in the top of the heater 9.2, and a heat medium inlet communicated with a concentrated heat source inlet 9.4 is formed in the middle of the heater 9.2; the lower part of the heater 9.2 is provided with a condensed water outlet which is communicated with a condensed water outlet 9.8.
The multiple-effect flash concentrator 9 is provided in plurality, and the reference to the multiple-effect flash concentrator 9 is along the medium flow direction: the heat medium outlet of the upstream multi-effect flash concentrator 9 is communicated with the heat medium inlet of the downstream multi-effect flash concentrator 9; the waste water outlet of the upstream multi-effect flash evaporator concentrator 9 is communicated with the waste water inlet of the downstream multi-effect flash evaporator concentrator 9, the heat medium outlet of the tail end multi-effect flash evaporator concentrator 9 is communicated with the desulfurizing tower 7 through the water vapor outlet 9.6, the waste water outlet of the tail end multi-effect flash evaporator concentrator 9 is communicated with the drying tower 10 through the concentrated solution outlet 9.7, the heat medium inlet of the start-end multi-effect flash evaporator concentrator 9 is communicated with the outlet of the flue gas cooler 4, and the circulating water outlet of each multi-effect flash evaporator concentrator 9 is communicated with the inlet of the flue gas cooler 4 through the condensed water outlet 9.8.
Referring to fig. 1 and 2: the desulfurization waste water treatment system of the coal-fired power plant based on the flue gas cooperative treatment has the advantages that the concentrated heat source adopts the high-temperature water 13, and the drying and conveying heat/gas sources adopt the high-temperature flue gas 14; taking a coal-fired power plant as an example, the temperature of the high-temperature water 14 can reach 90 ℃, and the temperature of the flue gas 14 can further reach 350 ℃, so that the arrangement can greatly improve the heat exchange end difference, improve the heat exchange efficiency and reduce the equipment volume.
The coal-fired power plant desulfurization wastewater zero-discharge treatment method based on flue gas cooperative treatment adjusts the pH value of the desulfurization wastewater to 7-8, then carries out concentration and evaporation on the desulfurization wastewater, and directly discharges water vapor to a flue; drying the concentrated solution to form crystallized fly ash 15, and recovering the crystallized fly ash 15; high-temperature flue gas 14 is used as a heat source for drying concentrated solution and an air source for assisting in conveying crystallized fly ash 15.
Referring to fig. 1, when the crystallized fly ash 15 is reinjected into the flue between the flue gas cooler 4 and the dust remover 5, the reinjection temperature is consistent with the original flue gas temperature in the flue, and the influence on the original flue gas air system is minimized.
Referring to FIG. 1: the desulfurization wastewater is injected with the regulator through the pH value regulating port 11, so that the pH value of the desulfurization wastewater is stabilized between 7 and 8, and the acidic corrosion of subsequent equipment is avoided.
Referring to fig. 1 and 2: the desulfurization wastewater treatment system of the coal-fired power plant based on the flue gas cooperative treatment has the advantages that concentrated water vapor is directly discharged to the desulfurization tower 7 for recycling, and crystallized fly ash 15 is reinjected to a flue between the flue gas cooler 4 and the dust remover 5 and is finally collected and discharged from the dust remover 5. Compared with the conventional flue gas drying process shown in the figure 3, the crystallized fly ash of the invention has no stacking and storage, is uniformly mixed with ash of a dust remover, has small mixing proportion, meets the comprehensive utilization standard of the ash, and better solves the problems of stacking, secondary disposal and the like of the dried fly ash. Meanwhile, since the bottom of the conventional drying tower 20 is in a completely dry state, when the gas is directly discharged, the gas is easy to carry fine dry particles, and the atmospheric environment and monitoring data are influenced by directly discharging the gas to a chimney.
Referring to fig. 1 and 3: the conventional flue injection scheme directly injects desulfurization wastewater into a flue, so that the humidity of flue gas is continuously increased, and equipment is corroded and damaged to a certain degree. The sectional design of concentrating and drying firstly and then better ensures the separation of the crystal particles and the water vapor, and avoids the risk of equipment corrosion.
The integrated treatment system for concentrating, drying and conveying the desulfurization wastewater based on the high-temperature flue gas is not limited in the form of a concentrated heat source in the system, can adopt high-temperature water 13 and other heat sources such as steam, and the drying tower 10 can adopt various forms such as a vertical type, a horizontal type and a rotary type, and only needs to meet the requirements of multi-effect concentration and high-temperature flue gas drying.
The above-mentioned parts not described in detail are prior art.
Claims (10)
1. A coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment is characterized by comprising a boiler (1), a denitration reactor (2), an air preheater (3), a flue gas cooler (4), a dust remover (5), an induced draft fan (6) and a desulfurization tower (7) which are sequentially communicated along the flow direction of flue gas; a desulfurization waste water outlet of the desulfurization tower (7) is sequentially communicated with a multi-effect flash evaporator concentrator (9) and a drying tower (10), and a pH value adjusting port (11) is arranged on the path from the desulfurization tower (7) to the multi-effect flash evaporator concentrator (9); a concentrated solution outlet (9.7) of the multi-effect flash evaporator concentrator (9) is communicated with an inlet of the drying tower (10), and a water vapor outlet (9.6) of the multi-effect flash evaporator concentrator (9) is communicated with the desulfurizing tower (7); the working medium inlet of the drying tower (10) is communicated with the flue gas outlet of the denitration reactor (2), and the outlet of the drying tower (10) is communicated with the dust remover (5).
2. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as defined in claim 1, wherein a wastewater delivery pump (16) is provided on the path of the desulfurization tower (7) to the multi-effect flash concentrator (9); a concentrated solution delivery pump (17) is arranged between a concentrated solution outlet (9.7) of the multi-effect flash evaporator concentrator (9) and an inlet of the drying tower (10); a condensed water circulating pump (18) is arranged between the condensed water outlet (9.8) and the inlet of the flue gas cooler (4); a crystallizing fly ash conveying pump (19) is arranged between the outlet of the drying tower (10) and the inlet of the dust remover (5).
3. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as defined in claim 1, wherein a flue at the outlet of the denitrification reactor (2) is divided into two parts, wherein one part of the flue is communicated with the air preheater (3), and the other part of the flue is communicated with the drying tower (10).
4. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as recited in claim 1, characterized in that the concentrated heat source inlet (9.4) of the multi-effect flash concentrator (9) is communicated with the outlet of the flue gas cooler (4), and the condensed water outlet (9.8) of the multi-effect flash concentrator (9) is communicated with the inlet of the flue gas cooler (4); the multi-effect flash evaporator concentrator (9) comprises a flash evaporation tank (9.1) and a heater (9.2), the bottom of the flash evaporation tank (9.1) is communicated with the bottom of the heater (9.2), the top end of the heater (9.2) is introduced into the upper part of the flash evaporation tank (9.1), and the bottom of the flash evaporation tank (9.1) is provided with a concentrated solution circulating pump (9.3); a wastewater inlet communicated with a desulfurization wastewater inlet (9.5) is formed in the top of the heater (9.2), and a heat medium inlet communicated with a concentrated heat source inlet (9.4) is formed in the middle of the heater (9.2); the lower part of the heater (9.2) is provided with a condensed water outlet which is communicated with a condensed water outlet (9.8).
5. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as defined in claim 1, wherein a plurality of multi-effect flash concentrators (9) are provided, and with reference to the plurality of multi-effect flash concentrators (9), along the medium flow direction: a heat medium outlet of the upstream multi-effect flash concentrator (9) is communicated with a heat medium inlet of the downstream multi-effect flash concentrator (9); the waste water outlet of the upstream direction multiple-effect flash evaporator concentrator (9) is communicated with the waste water inlet of the downstream direction multiple-effect flash evaporator concentrator (9), the heat medium outlet of the tail end multiple-effect flash evaporator concentrator (9) is communicated with the desulfurizing tower (7) through the water vapor outlet (9.6), the waste water outlet of the tail end multiple-effect flash evaporator concentrator (9) is communicated with the drying tower (10) through the concentrated solution outlet (9.7), the heat medium inlet of the starting end multiple-effect flash evaporator concentrator (9) is communicated with the outlet of the flue gas cooler (4), and the circulating water outlet of each multiple-effect flash evaporator concentrator (9) is communicated with the inlet of the flue gas cooler (4) through the condensed water outlet (9.8).
6. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as defined in claim 1, wherein the drying tower (10) is vertical, horizontal or rotary.
7. The coal-fired power plant desulfurization wastewater treatment system based on flue gas cooperative treatment as defined in claim 1, wherein a cooling device or a flow regulating valve is provided on the path from the drying tower (10) to the dust remover (5).
8. The coal-fired power plant desulfurization wastewater zero-discharge treatment method based on flue gas cooperative treatment is characterized in that the pH value of the desulfurization wastewater is adjusted to 7-8, then the desulfurization wastewater is concentrated and evaporated, and water vapor is directly discharged to a flue; drying the concentrated solution to form crystallized fly ash (15), and recovering the crystallized fly ash (15); high-temperature flue gas (14) is used as a heat source for drying concentrated solution and an air source for assisting in conveying crystallized fly ash (15).
9. The method for disposing the desulfurization wastewater of the coal-fired power plant as recited in claim 8, wherein the heat source for concentrating and evaporating the desulfurization wastewater is high-temperature water (13) heated by the flue gas cooler (4), the high-temperature water (13) is condensed into condensed water (12) after being operated, and the condensed water (12) enters the flue gas cooler (4) for heating circulation.
10. The method for disposing desulfurization wastewater of a coal-fired power plant according to claim 8, characterized in that the crystallized fly ash (15) is transported to a flue before the inlet of the dust collector (5), and when the crystallized fly ash (15) is reinjected to the flue, the reinjection temperature is the same as the temperature of the original flue gas in the flue.
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