CN110540257A - Coal fired power plant desulfurization waste water evaporative concentration and fresh water recovery device - Google Patents
Coal fired power plant desulfurization waste water evaporative concentration and fresh water recovery device Download PDFInfo
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- 239000002351 wastewater Substances 0.000 title claims abstract description 120
- 238000011084 recovery Methods 0.000 title claims abstract description 71
- 239000013505 freshwater Substances 0.000 title claims abstract description 70
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 27
- 230000023556 desulfurization Effects 0.000 title claims abstract description 27
- 239000003245 coal Substances 0.000 title claims description 13
- 238000001704 evaporation Methods 0.000 claims abstract description 99
- 230000008020 evaporation Effects 0.000 claims abstract description 96
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 79
- 238000009833 condensation Methods 0.000 claims abstract description 63
- 230000005494 condensation Effects 0.000 claims abstract description 63
- 239000002918 waste heat Substances 0.000 claims abstract description 49
- 239000000945 filler Substances 0.000 claims abstract description 41
- 239000010802 sludge Substances 0.000 claims abstract description 29
- 238000001816 cooling Methods 0.000 claims abstract description 23
- 239000003570 air Substances 0.000 claims description 37
- 239000000463 material Substances 0.000 claims description 13
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 12
- 229910052719 titanium Inorganic materials 0.000 claims description 12
- 239000010936 titanium Substances 0.000 claims description 12
- 239000012080 ambient air Substances 0.000 claims description 10
- 230000007797 corrosion Effects 0.000 claims description 9
- 238000005260 corrosion Methods 0.000 claims description 9
- 229910001220 stainless steel Inorganic materials 0.000 claims description 9
- 239000010935 stainless steel Substances 0.000 claims description 9
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 8
- 239000000498 cooling water Substances 0.000 claims description 8
- 239000003546 flue gas Substances 0.000 claims description 8
- 239000004033 plastic Substances 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 6
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 239000010865 sewage Substances 0.000 claims description 3
- 239000012141 concentrate Substances 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 229910052755 nonmetal Inorganic materials 0.000 abstract 1
- 238000000034 method Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 9
- 229920006395 saturated elastomer Polymers 0.000 description 9
- 230000008569 process Effects 0.000 description 7
- 239000007787 solid Substances 0.000 description 6
- 230000018044 dehydration Effects 0.000 description 4
- 238000006297 dehydration reaction Methods 0.000 description 4
- 208000028659 discharge Diseases 0.000 description 4
- 239000000428 dust Substances 0.000 description 4
- 239000000779 smoke Substances 0.000 description 4
- 230000009467 reduction Effects 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003009 desulfurizing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 229920002313 fluoropolymer Polymers 0.000 description 1
- 239000010842 industrial wastewater Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000008234 soft water Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
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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
-
- 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
- C02F1/043—Details
-
- 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
- C02F1/048—Purification of waste water by evaporation
-
- 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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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
Abstract
The invention discloses a desulfurization wastewater evaporative concentration and fresh water recovery device for a coal-fired power plant, which comprises a filler type evaporative concentration tower provided with a wastewater pool, a condensing tower, a connecting air pipe, a wastewater circulating pump, a sludge pump, a condensation heat recovery heat exchanger, a waste heat reheater, a cooling circulating pump and a cooler, wherein the cooling circulating pump is connected with the waste heat reheater; the wastewater tank is connected with a sludge pump through a blow-off pipe, and the outlet of the sludge pump is connected to a sludge dewatering workshop; the fresh water collecting pool conveys the fresh water to fresh water users through a water pump; the inlet of the condenser is connected with the outlet of the cooling circulating pump, and the outlet of the condenser is connected with the inlet of the hot side of the condensation heat recovery heat exchanger. The invention utilizes the non-metal filler type evaporation mode to evaporate and concentrate the waste water, and utilizes the waste heat resource and the mode of recovering the condensation heat of the fresh water to provide a heat source for the evaporation equipment, thereby achieving the purposes of saving the investment of the waste water evaporation and concentration system and saving the energy consumption cost for operation, and greatly improving the operation reliability of the system compared with the traditional evaporation and concentration system.
Description
Technical Field
The invention relates to the technical field of energy conservation and emission reduction of coal-fired power plants, in particular to a desulfurization wastewater evaporation concentration and fresh water recovery device of a coal-fired power plant.
Background
The existing thermal method evaporation concentration mainly comprises an evaporation concentration route represented by multi-effect evaporation or MVR evaporation and a flue type evaporation route, wherein solid matters in the waste water are collected in a form of crystallized salt, evaporated fresh water can be condensed for reuse, but the system is complex, the requirements on pretreatment and softening treatment of the waste water are high, and the initial investment and the operating cost of the system are high; the latter system is simple, the requirement on wastewater pretreatment is low, the investment and the operation cost are low, but the solid matters in the wastewater are collected into the smoke dust, the harmful solid matters in the wastewater are not collected and concentrated but diffused into the environment along with the smoke dust, and although the system meets the current environmental protection standard, the system does not meet the development direction of environmental protection technology strictly; in addition, the two technical routes both face the problem of low reliability in the practical engineering practice process.
In view of the disadvantages of the existing desulfurization wastewater zero-discharge treatment technology, a more reliable wastewater zero-discharge treatment mode with lower cost needs to be found.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a coal-fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device, which utilizes waste heat of a power plant as an evaporative concentration heat source and adopts a filler type evaporation technology to concentrate desulfurization wastewater and a wet surface type cooling to recover fresh water so as to realize zero emission treatment of desulfurization wastewater.
The invention is realized by the following technical scheme: a desulfurization wastewater evaporative concentration and fresh water recovery device for a coal-fired power plant comprises a filler type evaporative concentration tower, a condensing tower, a connecting air pipe, a wastewater circulating pump, a sludge pump, a condensation heat recovery heat exchanger, a waste heat reheater, a cooling circulating pump and a cooler; the evaporation concentration tower comprises an air inlet grille, evaporation filler and a first water baffle, the evaporation concentration tower is connected with the condensation tower through the connecting air pipe, and the lower part of the evaporation concentration tower is provided with a wastewater pool; the evaporation filler is positioned in the evaporation concentration tower, and a water distributor is arranged on the evaporation concentration tower above the evaporation filler; the condensing tower is a coil pipe type/pipe plate type condensing tower and comprises a condenser, a second water baffle and an induced draft fan; an inlet of the wastewater circulating pump is connected with the wastewater pool through a connecting pipe, an outlet of the wastewater circulating pump is sequentially communicated with the condensation heat recovery heat exchanger and the waste heat reheater through the connecting pipe, and an outlet of the waste heat reheater is communicated with the water distributor; the hot side of the condensation heat recovery heat exchanger is connected with the condenser through a hot water inflow pipe, and the hot side of the condensation heat recovery heat exchanger is connected with the hot side inlet of the cooler through a hot water outflow pipe; the wastewater tank is connected with the sludge pump through a sewage discharge pipe, and the outlet of the sludge pump is connected to a sludge dewatering workshop; the fresh water collecting pool is provided with a fresh water conveying outlet, and the fresh water conveying outlet conveys fresh water to fresh water users through a water pump; the inlet of the condenser is connected with the outlet of the cooling circulating pump, and the outlet of the condenser is connected with the inlet of the hot side of the condensation heat recovery heat exchanger; and a hot side outlet of the cooler is connected with an inlet of the cooling circulating pump, and a cold side inlet and a cold side outlet of the cooler are respectively connected to an outlet and an inlet of a cooling tower cooled by circulating water in a plant area.
Waste water passes through a condensation heat recovery heat exchanger and a waste heat reheater by a waste water circulating pump in sequence, absorbs part of fresh water condensation heat of a cooler and waste heat recovered by a low-temperature waste heat recovery system, then the temperature is raised to be more than 87 ℃, the waste water is sprayed by a water distributor to enter an evaporation filler and form a water film for evaporation, and the waste water is concentrated in continuous circulating spraying and evaporation; the bottom of the wastewater pool is provided with a sludge or slurry discharge pipe, the thick pus waste liquid is pumped to a dehydrator of a sludge dehydration workshop by a sludge pump for dehydration, the dehydrator can be a centrifugal dehydrator, the dehydrated solid matters are separately treated, and the dehydrated water can return to the wastewater pool of the evaporation concentration tower. After the wastewater is evaporated in the filler type evaporation concentration tower, saturated air or nearly saturated air is sucked into the condensation tower through the induced draft fan, condensed on the surface of the cooler and finally converged into a fresh water collecting tank at the lower part of the condensation tower.
The evaporation filler is made of materials with acid corrosion resistance and temperature resistance, the filler is polytetrafluoroethylene, and the filler is in a pall ring or a stepped ring shape. The selected filler can increase the surface evaporation capacity and is convenient to wash the filler form which is not easy to block.
The water distributor adopts a plastic nozzle with acid corrosion resistance and temperature resistance. The plastic nozzle has strong corrosion resistance and is not easy to block.
The condenser adopts a coil pipe type or a pipe plate type condenser, and the material of the condenser adopts 316L stainless steel.
The condensation heat recovery heat exchanger adopts a tubular or plate heat exchanger.
The parts of the condensation heat recovery heat exchanger, which are in direct contact with the wastewater, are made of titanium tubes, and the other parts, which are not in direct contact with the wastewater, are made of stainless steel; when the condensation heat recovery heat exchanger adopts a plate heat exchanger, the condensation heat recovery heat exchanger is made of titanium materials.
The heat source of the waste heat reheater is hot water or exhaust steam produced by the low-temperature flue gas waste heat recovery heat exchanger of the power plant; when dead steam is adopted, the pressure of the dead steam is 0.1 MPa; when the hot water supplied by the low-temperature flue gas waste heat recovery heat exchanger is adopted, the temperature of the hot water is not lower than 92 ℃.
The waste heat reheater adopts a tubular or plate heat exchanger; when the heat exchange tube of the tube heat exchanger is adopted, the component which is in direct contact with the waste water is made of a titanium tube, and other components which are not in direct contact with the waste water are made of stainless steel; when a plate heat exchanger is adopted, the waste heat reheater is made of titanium.
The temperature of the cooling water at the inlet of the condenser is not higher than 52 ℃, and the cooling water adopted by the condensing tower is softened water.
The carrier medium adopted for evaporating the waste water of the evaporation concentration tower is ambient air, and the carrier medium adopted for condensing and recovering the fresh water evaporated by the condensation tower is ambient air. The evaporation concentration tower and the condensation tower adopt ambient air as a carrier medium, and the evaporation concentration of the wastewater and the condensation recovery of fresh water are realized by utilizing the difference of the moisture content of saturated air at different temperatures.
Compared with the prior art, the invention has the advantages that: the invention utilizes the waste heat of a power plant as an evaporation concentration heat source, utilizes the difference of the water vapor capacity carried by saturated air at different temperatures, and adopts the filler type evaporation technology to concentrate the desulfurization wastewater and the wet surface type cooling and dehumidifying mode to recover the fresh water carried by the air so as to achieve the purposes of zero emission treatment of the desulfurization wastewater and recovery of the fresh water. The waste heat resources of the power plant are utilized, and the fresh water condensation heat is partially recovered, so that the energy cost of the system is greatly reduced; and because the difference of the water content mass fraction of saturated air at different temperatures is utilized, the purpose of evaporation concentration is achieved by increasing the surface evaporation temperature of the wastewater, the air temperature is reduced through a dividing wall type wet surface condenser, the water content mass fraction of the air is reduced to dehumidify, the fresh water is recovered, the temperature of circulating cooling water of a condensing tower is further reduced through a condensation heat recovery heat exchanger, part of condensation latent heat of the fresh water absorbed by a surface cooler is transferred into the wastewater, the requirement on waste heat in the wastewater heating process is reduced, and therefore the system energy consumption is reduced, and the energy cost is further reduced. Because of the adoption of the filler type surface evaporation and the large-flow plastic nozzle, the wastewater enters the evaporation concentration process and has no special requirements on the quality of the wastewater, even does not need softening treatment, but has the anti-scaling requirement on the material selection of the wastewater circulating pump when the wastewater is not softened.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
The reference numerals in the drawings mean: 1. an air inlet grille; 2. evaporating the filler; 31. a first water baffle; 32. A second water baffle; 4. connecting an air pipe; 5. a condenser; 6. an induced draft fan; 7. an evaporation concentration tower; 8. A condensing tower; 9. a wastewater tank; 10. a wastewater circulating pump; 101. a sludge pump; 11. a condensation heat recovery heat exchanger; 12. a waste heat reheater; 13. a water distributor; 14. a cooling circulation pump; 15. a fresh water collecting tank; 16. A cooler; A. the direction of air intake; B. the air outlet direction; C. pretreating the system to obtain wastewater; D. dewatering the sludge; E. to a cooling tower; F. to the fresh water user; G. waste heat (hot water).
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and detailed description.
Examples
Referring to fig. 1, the desulfurization wastewater evaporative concentration and fresh water recovery device for a coal-fired power plant comprises a filler-type evaporative concentration tower 7, a condensing tower 8, a connecting air pipe 4, a wastewater circulating pump 10, a sludge pump 101, a condensation heat recovery heat exchanger 11, a waste heat reheater 12, a cooling circulating pump 14 and a cooler 16; the evaporation concentration tower 7 comprises an air inlet grille 1, evaporation filler 2 and a first water baffle 31, the evaporation concentration tower 7 is connected with a condensing tower 8 through a connecting air pipe 4, and the lower part of the evaporation concentration tower 7 is provided with a wastewater pool 9; the evaporation filler 2 is positioned in the evaporation concentration tower 7, and a water distributor 13 is arranged on the evaporation concentration tower 7 above the evaporation filler 2; the condensing tower 8 is a coil pipe type/tube plate type condensing tower 8 and comprises a condenser 5, a second water baffle 32 and an induced draft fan 6; an inlet of a wastewater circulating pump 10 is connected with a wastewater tank 9 through a connecting pipe, an outlet of the wastewater circulating pump 10 is sequentially communicated with a condensation heat recovery heat exchanger 11 and a waste heat reheater 12 through connecting pipes, and an outlet of the waste heat reheater 12 is communicated with a water distributor 13; the hot side of the condensation heat recovery heat exchanger 11 is connected with the condenser 5 through a hot water inflow pipe, and the hot side of the condensation heat recovery heat exchanger 11 is connected with the hot side inlet of the cooler 16 through a hot water outflow pipe; the wastewater tank 9 is connected with a sludge pump 101 through a sewage discharge pipe, and the outlet of the sludge pump 101 is connected to a sludge dewatering workshop; the fresh water collecting pool 15 is provided with a fresh water conveying outlet which conveys fresh water to fresh water users through a water pump; the inlet of the condenser 5 is connected with the outlet of the cooling circulating pump 14, and the outlet of the condenser 5 is connected with the hot side inlet of the condensation heat recovery heat exchanger 11; the outlet of the hot side of the cooler 16 is connected with the inlet of the cooling circulation pump 14, and the inlet and the outlet of the cold side of the cooler 16 are respectively connected with the outlet and the inlet of a cooling tower cooled by the circulating water in the plant area. The condenser 5 of the present application is a wet surface condenser 5. Referring to fig. 1, arrows or letters in the drawing are respectively represented as: A. the direction of air intake; B. the air outlet direction; C. pretreating the system to obtain wastewater; D. dewatering the sludge; E. to a cooling tower; F. to the fresh water user; G. waste heat (hot water).
The waste water passes through a condensation heat recovery heat exchanger 11 and a waste heat reheater 12 by a waste water circulating pump 10, absorbs part of fresh water condensation heat of a cooler 16 and waste heat recovered by a low-temperature waste heat recovery system, the temperature is raised to be more than 87 ℃, the waste water is sprayed into an evaporation filler 2 by a water distributor 13 to form a water film for evaporation, and the waste water is concentrated in continuous circulating spraying and evaporation; the bottom of the wastewater pool 9 is provided with a sludge or slurry discharge pipe, the thick and pus waste liquid is pumped to a dehydrator of a sludge dehydration workshop through a sludge pump 101 for dehydration, the dehydrator can be a centrifugal dehydrator, the dehydrated solid matters are separately treated, and the dehydrated water can return to the wastewater pool 9 of the evaporation concentration tower 7. After being evaporated in the filler type evaporation concentration tower 7, the wastewater is sucked into the condensing tower 8 through the induced draft fan 6 by saturated air or nearly saturated air, condensed on the surface of the cooler 16, and finally converged into the fresh water collecting tank 15 at the lower part of the condensing tower 8.
The evaporation filler 2 is made of materials with acid corrosion resistance and temperature resistance, the filler is polytetrafluoroethylene, and the filler is in the shape of a pall ring or a stepped ring. The selected filler can increase the surface evaporation capacity and is convenient to wash the filler form which is not easy to block. The temperature resistance of the filler in the embodiment is a medium temperature resistant grade material, most of sprayed hot wastewater is in a water film shape on the surface of the filler, and the partial pressure of water vapor on the surface of the water film and the partial pressure of water vapor in air flow have a pressure difference to form a water film evaporation driving force to promote the evaporation of the wastewater; a small proportion of the water droplets undergo evaporation from the surface of the droplets in collisions with the air stream.
The water distributor 13 adopts a plastic nozzle with acid corrosion resistance and temperature resistance. The plastic nozzle has strong corrosion resistance and is not easy to block. The plastic nozzle of the water distributor 13 is made of a high-flow medium temperature resistant material.
The condenser 5 adopts a coil type or a tube plate type condenser 5, and the material of the condenser is 316L stainless steel.
The condensation heat recovery heat exchanger 11 is a tube type or plate type heat exchanger. The condensation heat recovery heat exchanger 11 recovers part of the fresh water condensation heat of the cooler 16 for preheating the circulating wastewater, and a tube type or plate type heat exchanger can be adopted.
The parts of the condensation heat recovery heat exchanger 11 which are in direct contact with the wastewater are made of titanium tubes, and other parts which are not in direct contact with the wastewater are made of stainless steel; when the condensation heat recovery heat exchanger 11 is a plate heat exchanger, the condensation heat recovery heat exchanger 11 is made of a titanium material.
The heat source of the waste heat reheater 12 is hot water or exhaust steam produced by the low-temperature flue gas waste heat recovery heat exchanger of the power plant; when dead steam is adopted, the pressure of the dead steam is 0.1 MPa; when the hot water supplied by the low-temperature flue gas waste heat recovery heat exchanger is adopted, the temperature of the hot water is not lower than 92 ℃.
The waste heat reheater 12 adopts a tubular or plate heat exchanger; when the heat exchange tube of the tube heat exchanger is adopted, the component which is in direct contact with the waste water is made of a titanium tube, and other components which are not in direct contact with the waste water are made of stainless steel; when a plate heat exchanger is used, the waste heat reheater 12 is made of titanium.
After being heated by the condensation heat recovery heat exchanger 11 and the waste heat reheater 12, the waste water is heated to 87-89 ℃, and then is dispersed to the evaporation filler 2 through the water distributor 13 for surface evaporation concentration.
The temperature of cooling water at the inlet of the condenser 5 is not higher than 52 ℃, and the cooling water adopted by the condensing tower 8 is softened water.
The carrier medium adopted by the evaporation of the waste water in the evaporation concentration tower 7 is ambient air, and the carrier medium adopted by the condensation and recovery of the fresh water evaporated in the condensation tower 8 is ambient air. The evaporation concentration tower 7 and the condensation tower 8 adopt ambient air as a carrier medium, and the evaporation concentration of wastewater and the condensation recovery of fresh water are realized by utilizing the difference of the moisture content of saturated air at different temperatures.
The desulfurization wastewater evaporative concentration and fresh water recovery device for the coal-fired power plant aims to develop a method and a technology for desulfurization wastewater zero-emission treatment by concentrating desulfurization wastewater by adopting a filler type evaporation technology and recovering fresh water by adopting wet surface cooling, and uses 'cheap' waste heat and recovered partial fresh water condensation heat of the power plant as a wastewater evaporative concentration heat source, so that the energy cost for evaporative concentration is greatly reduced; by adopting a filler type evaporation low-temperature evaporation technology, warm waste water is sprayed to the surface of a filler through a large-flow plastic nozzle to form water film surface evaporation, the difference between the water vapor partial pressure on the water film surface and the water vapor partial pressure in the air is used as an evaporation driving force, and the evaporated water is brought to a condensing tower 8 by the air; the wet surface type cooling and condensing technology is adopted, fresh water is recovered through temperature reduction and humidity reduction, and partial condensation latent heat of the fresh water is recovered.
In the embodiment, the heat required by evaporation concentration is partly (about half) from waste heat of the power plant, and partly from latent heat of condensation recovered by condensation of fresh water; the waste heat can be hot water generated by a low-temperature flue gas waste heat recovery heat exchanger at the outlet of the dry dust collector, or dead steam at the low-pressure end of a steam turbine, and the low-temperature flue gas waste heat is preferably utilized under certain conditions. The method comprises the steps of taking ambient air as a medium, bringing evaporated moisture in the wastewater to a fresh water condensation recovery tower, changing the ambient air with low temperature and low humidity into a packed tower by utilizing the difference of the water content mass fraction of saturated air at different temperatures, absorbing the water and latent heat evaporated from a water film on the surface of the packed tower and the sensible heat of warm wastewater into high-temperature and high-humidity air, cooling and dehumidifying the air by a wet surface cooler 16 (namely the cooler 16 in the embodiment) after the air enters a condensation tower 8, and diffusing the air by an induced draft fan 6 after fresh water is separated out. Under the action of a wastewater circulating pump 10, wastewater firstly passes through a condensation heat recovery heat exchanger 11 to absorb part of fresh water condensation heat from a wet-type surface condenser 5, then passes through a waste heat reheater 12 to continuously absorb part of heat, the temperature is raised to be more than 87 ℃, the wastewater enters a water distributor 13 of an evaporation concentration tower 7, the wastewater is sprayed to the surface of an evaporation filler 2 through a nozzle of the water distributor 13, evaporation concentration is carried out after meeting air flow, and part of water is released and then returns to a wastewater pool 9 at the lower part of the evaporation concentration tower 7. And a sludge discharge pipe is arranged at the bottom of the wastewater tank 9, sludge or slurry with thick bottom is pumped to a sludge dewatering workshop through a sludge pump 101 for dewatering, the removed water flows back to the wastewater tank 9, and the dewatered mud cake is sealed for storage or is transported outside for disposal. The fresh water and the condensation latent heat of the condensing tower 8 are recovered by taking the soft water as a medium, the condensed and separated fresh water is collected in a fresh water collecting tank 15 and then is pumped to plant users, part of heat absorbed by the wet surface cooler 16 is used for heating the waste water (through the condensation heat recovery heat exchanger 11), and the other part of latent heat is taken away through a plant circulating cooling water system.
Compared with an evaporation concentration system represented by multi-effect evaporation or MVR evaporation, the evaporation process of the device for evaporative concentration and fresh water recovery of desulfurization wastewater of a coal-fired power plant has lower requirement on the quality of heat, waste heat of the power plant can be utilized, partial condensed latent heat of fresh water can be recovered, high-quality fresh steam is not needed, compression work is not needed in the process of recovering the condensed latent heat, only a fan and a water pump of an intermediate medium (air or circulating water) need to be driven to consume power, and the power consumption of evaporation concentration of wastewater per ton of water is only 25% -30% of that of the MVR system; in addition, the evaporation concentration process is completed at a medium-low temperature, corrosion-resistant materials such as fluoroplastics and the like are adopted, the wastewater can be treated without softening, the wastewater pretreatment cost is greatly reduced, the adopted pall ring and step ring packing are easy to wash, the problem of scaling and blocking of a heat exchanger is avoided, and the operation reliability of a system is greatly improved. Compared with the flue evaporation type waste water treatment zero emission technology, although the equipment investment is increased, the problem of nozzle blockage is not worried about, the problem of influence on the operation performance of a rear system such as a dust remover and a desulfurizing tower worried about by a flue evaporation process is not worried about, the problem of flue blockage is not worried about, the power generation coal consumption of a power plant unit is hardly influenced, and the worry that the resource utilization is influenced by the salt content in the smoke caused by the fact that solid matters enter the smoke after waste water evaporation in the flue evaporation is avoided. In the embodiment, the initial investment of the equipment is equivalent to or slightly lower than that of an MVR evaporation and concentration system, but because softening treatment is not needed, most of water treatment cost is saved, the running energy cost is only one fourth of that of the MVR system, and the actual running comprehensive cost is about one third of that of the MVR evaporation and crystallization wastewater zero-discharge treatment system.
It should be particularly noted that, the wastewater evaporation and concentration mode of the coal-fired power plant desulfurization wastewater evaporation and concentration and fresh water recovery device of the embodiment is also suitable for other industrial wastewater evaporation and concentration and zero discharge processes with waste heat resources.
The above detailed description is specific to possible embodiments of the present invention, and the embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications that do not depart from the scope of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The utility model provides a coal fired power plant desulfurization waste water evaporative concentration and fresh water recovery unit which characterized in that: the device comprises a filler type evaporation concentration tower, a condensing tower, a connecting air pipe, a wastewater circulating pump, a sludge pump, a condensation heat recovery heat exchanger, a waste heat reheater, a cooling circulating pump and a cooler; the evaporation concentration tower comprises an air inlet grille, evaporation filler and a first water baffle, the evaporation concentration tower is connected with the condensation tower through the connecting air pipe, and the lower part of the evaporation concentration tower is provided with a wastewater pool; the evaporation filler is positioned in the evaporation concentration tower, and a water distributor is arranged on the evaporation concentration tower above the evaporation filler; the condensing tower is a coil pipe type/pipe plate type condensing tower and comprises a condenser, a second water baffle and an induced draft fan; an inlet of the wastewater circulating pump is connected with the wastewater pool through a connecting pipe, an outlet of the wastewater circulating pump is sequentially communicated with the condensation heat recovery heat exchanger and the waste heat reheater through the connecting pipe, and an outlet of the waste heat reheater is communicated with the water distributor; the hot side of the condensation heat recovery heat exchanger is connected with the condenser through a hot water inflow pipe, and the hot side of the condensation heat recovery heat exchanger is connected with the hot side inlet of the cooler through a hot water outflow pipe; the wastewater tank is connected with the sludge pump through a sewage discharge pipe, and the outlet of the sludge pump is connected to a sludge dewatering workshop; the fresh water collecting pool is provided with a fresh water conveying outlet, and the fresh water conveying outlet conveys fresh water to fresh water users through a water pump; the inlet of the condenser is connected with the outlet of the cooling circulating pump, and the outlet of the condenser is connected with the inlet of the hot side of the condensation heat recovery heat exchanger; and a hot side outlet of the cooler is connected with an inlet of the cooling circulating pump, and a cold side inlet and a cold side outlet of the cooler are respectively connected to an outlet and an inlet of a cooling tower cooled by circulating water in a plant area.
2. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the evaporation filler is made of materials with acid corrosion resistance and temperature resistance, the filler is polytetrafluoroethylene, and the filler is in a pall ring or a stepped ring shape.
3. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the water distributor adopts a plastic nozzle with acid corrosion resistance and temperature resistance.
4. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the condenser adopts a coil pipe type or a pipe plate type condenser, and the material of the condenser adopts 316L stainless steel.
5. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the condensation heat recovery heat exchanger adopts a tubular or plate heat exchanger.
6. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 5, characterized in that: the parts of the condensation heat recovery heat exchanger, which are in direct contact with the wastewater, are made of titanium tubes, and the other parts, which are not in direct contact with the wastewater, are made of stainless steel; when the condensation heat recovery heat exchanger adopts a plate heat exchanger, the condensation heat recovery heat exchanger is made of titanium materials.
7. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the heat source of the waste heat reheater is hot water or exhaust steam produced by the low-temperature flue gas waste heat recovery heat exchanger of the power plant; when dead steam is adopted, the pressure of the dead steam is 0.1 MPa; when the hot water supplied by the low-temperature flue gas waste heat recovery heat exchanger is adopted, the temperature of the hot water is not lower than 92 ℃.
8. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 7, characterized in that: the waste heat reheater adopts a tubular or plate heat exchanger; when the heat exchange tube of the tube heat exchanger is adopted, the component which is in direct contact with the waste water is made of a titanium tube, and other components which are not in direct contact with the waste water are made of stainless steel; when a plate heat exchanger is adopted, the waste heat reheater is made of titanium.
9. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the temperature of the cooling water at the inlet of the condenser is not higher than 52 ℃, and the cooling water adopted by the condensing tower is softened water.
10. The coal fired power plant desulfurization wastewater evaporative concentration and fresh water recovery device of claim 1, characterized in that: the carrier medium adopted for evaporating the waste water of the evaporation concentration tower is ambient air, and the carrier medium adopted for condensing and recovering the fresh water evaporated by the condensation tower is ambient air.
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