High-salinity wastewater zero discharge system
By utilizing waste heat from flue gas for heat exchange in a zero-discharge system for high-salt wastewater, the problems of low concentration ratio and limited treatment capacity are solved, achieving efficient wastewater treatment and reducing costs and system complexity.
Patent Information
- Application Number
- CN202422692033.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-10-31
- Estimated Expiration
- 2034-11-05
AI Technical Summary
Existing high-salinity wastewater treatment systems have low concentration ratios, and the wastewater treatment capacity is greatly affected by the unit load, resulting in high treatment costs, complex systems, and large footprints.
A zero-discharge system for high-salinity wastewater is adopted, including a high-salinity wastewater tank, a pretreatment system, a concentration tower, a concentrated liquid wastewater tank, an evaporation tower, and a heat exchanger. Heat exchange is carried out through circulating pumps and spray devices, and the waste heat of flue gas is used to concentrate and evaporate the wastewater, thereby increasing the concentration ratio and treatment capacity.
The concentration ratio of the thickening tower was increased, the wastewater treatment cost was reduced, the load limitation on the unit was reduced, and efficient wastewater treatment was achieved.
Smart Images
Figure CN223496233U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of high-salinity wastewater treatment technology, and in particular to a zero-discharge system for high-salinity wastewater. Background Technology
[0002] Thermal power plants generate wastewater from circulating water systems, desulfurization wastewater from limestone-gypsum wet desulfurization systems, and reverse osmosis wastewater. This wastewater contains many toxic and harmful substances and requires treatment to meet discharge standards. Due to the diverse types and varying volumes of wastewater, treating it is challenging, and these methods generally suffer from system complexity, large footprint, and high operating costs.
[0003] The concentration process in existing high-salinity wastewater treatment systems mainly involves using the waste heat of flue gas to contact the high-salinity wastewater in a concentration tower for concentration. However, the concentration ratio is not high, and the wastewater treatment capacity is greatly affected by the unit load, resulting in limited treatment capacity and relatively high cost. Based on the above problems, a new zero-discharge system for high-salinity wastewater is provided. Utility Model Content
[0004] This invention provides a zero-discharge system for high-salt wastewater, with a higher concentration ratio in the concentration tower, resulting in a higher wastewater treatment capacity and relatively lower treatment costs.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] A zero-discharge system for high-salinity wastewater includes a high-salinity wastewater tank, a pretreatment system, a concentration tower, a concentrated liquid wastewater tank, an evaporation tower, and a heat exchanger.
[0007] The outlet of the aforementioned high-salt wastewater pond, the aforementioned pretreatment system, and the aforementioned concentration tower are connected in sequence.
[0008] The first outlet of the concentration tower, the concentrated liquid wastewater pool and the inlet of the evaporation tower are connected in sequence. The flue gas inlet of the evaporation tower is connected to the SCR outlet flue. The flue gas outlet of the evaporation tower is connected to the dust collector inlet flue. The flue gas inlet, water inlet and flue gas outlet of the evaporation tower are arranged from top to bottom.
[0009] A circulating pump is connected to the second outlet of the above-mentioned concentration tower. The inlet of the heat exchanger is connected to the outlet of the circulating pump. The outlet is connected to the spray device at the top of the concentration tower. The flue gas inlet is connected to the flue gas outlet of the evaporation tower. The flue gas outlet is connected to the inlet flue of the dust collector.
[0010] The inlet of the aforementioned concentration tower is connected to the outlet flue of the dust collector, and its outlet is connected to the inlet flue of the desulfurization tower. The outlet, spray device, and inlet of the aforementioned concentration tower are arranged sequentially from top to bottom.
[0011] Preferably, a first pipe is connected between the outlet of the high-salt wastewater tank and the inlet of the pretreatment system, and a first pump and a first electric valve are sequentially installed on the first pipe along the water flow direction.
[0012] A second pipe connects the outlet of the pretreatment system and the inlet of the concentration tower. The second pipe is equipped with a second pump and a second electric valve in sequence along the water flow direction.
[0013] Preferably, a third pipe connects the dust collector outlet flue to the thickening tower inlet, and an electric damper, a third electric valve, and a fan are sequentially installed on the third pipe along the flue gas flow direction.
[0014] Preferably, a fourth pipe is connected between the above-mentioned concentrated wastewater pool and the first outlet of the above-mentioned concentration tower, and a third pump is installed on the above-mentioned fourth pipe;
[0015] A fifth pipe connects the outlet of the above-mentioned concentrated wastewater pool and the inlet of the above-mentioned evaporation tower. The fifth pipe is connected to an atomizing water pump, which is equipped with a frequency converter.
[0016] Preferably, the flue gas outlet of the evaporator is connected to a sixth pipe, a fourth electric valve is connected to the sixth pipe, a seventh pipe is connected between the sixth pipe and the flue gas inlet of the heat exchanger, a sixth electric valve is provided on the seventh pipe, and the sixth pipe is connected to the inlet flue of the dust collector.
[0017] Preferably, the discharge port of the evaporator is equipped with an ash conveying system.
[0018] Preferably, the pretreatment system can be one or more of a triplex tank, a sedimentation tank, and a mechanically accelerated stirring clarification tank.
[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0020] 1. By using the waste heat of flue gas to heat the circulating high-salt wastewater in the thickening tower through a heat exchanger, the temperature of the high-salt wastewater is increased. Then, it re-enters the thickening tower to exchange heat with the flue gas again, making it easier for the water in the high-salt wastewater to evaporate. Compared with existing technologies, this method has lower load restrictions on the unit, larger wastewater treatment capacity, and higher concentration ratio.
[0021] 2. The flue gas at the outlet of the evaporator first passes through a heat exchanger to heat the wastewater in the low-temperature flue gas concentration tower before returning to the dust collector, thus making full use of the waste heat of the flue gas in the evaporator. Attached Figure Description
[0022] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of a system according to an embodiment of the present invention.
[0024] Explanation of reference numerals in the attached figures:
[0025] 1. High-salinity wastewater tank; 2. Pretreatment system; 3. Concentration tower; 4. Evaporation tower; 5. Heat exchanger; 6. Circulation pump; 7. First pipe; 8. First pump; 9. First electric valve; 10. Second pipe; 11. Second pump; 12. Second electric valve; 13. Third pipe; 14. Electric damper; 15. Third electric valve; 16. Fan; 17. Fourth pipe; 18. Third pump; 19. Fifth pipe; 20. Atomizing water pump; 21. Sixth pipe; 22. Fourth electric valve; 23. Seventh pipe; 24. Fifth electric valve; 25. Eighth pipe. Detailed Implementation
[0026] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.
[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0029] like Figure 1As shown, this utility model embodiment provides a zero-discharge system for high-salinity wastewater, including a high-salinity wastewater tank 1, a pretreatment system 2, a concentration tower 3, a concentrated wastewater tank, an evaporation tower 4, and a heat exchanger 5. The high-salinity wastewater tank 1 is used for temporary storage of high-salinity wastewater. The outlet of the high-salinity wastewater tank 1, the inlet of the pretreatment system 2, and the inlet of the concentration tower 3 are sequentially connected, so that the high-salinity wastewater first enters the pretreatment system 2 for pretreatment. The pretreatment system 2 can be one or more of the existing triplet, sedimentation tank, and mechanically accelerated stirring clarification tank processes. The added agents are flocculants, coagulants, etc., and can be one or more of these. The suspended solids in the effluent after the pretreatment system 2 are ≤100mg / L. The pretreated wastewater then enters the concentration tower 3 for concentration. The first outlet of the concentration tower 3, the concentrated wastewater pool, and the inlet of the evaporation tower 4 are connected in sequence. The concentrated water after concentration in the concentration tower 3 first enters the concentrated wastewater pool for short-term storage, and then enters the evaporation tower 4 for evaporation and crystallization. Finally, it is discharged from the lower outlet of the evaporation tower 4. The flue gas inlet of the evaporation tower 4 is connected to the SCR outlet flue, and the flue gas outlet of the evaporation tower 4 is connected to the dust collector inlet flue. The flue gas inlet, water inlet, and flue gas outlet of the evaporation tower 4 are arranged from top to bottom. The wastewater entering the evaporation tower 4 flows downward, and the flue gas at the SCR outlet flue enters the evaporation tower 4 and exchanges heat with the wastewater in the evaporation tower 4, thereby evaporating the water and crystallizing it out. The crystals then flow out through the lower outlet of the evaporation tower 4 and are transported out via the matching ash conveying system. The high-salt wastewater entering the thickening tower 3 is connected to the second outlet of the thickening tower 3 via a circulating pump 6. The inlet of the heat exchanger 5 is connected to the outlet of the circulating pump 6, and the outlet is connected to the spray device at the top of the thickening tower 3. The flue gas inlet is connected to the flue gas outlet of the evaporator 4, and the flue gas outlet is connected to the inlet flue of the dust collector. The high-salt wastewater then enters the thickening tower 3 via the circulating pump 6 and enters the heat exchanger 5 to exchange heat with the flue gas from the evaporator 4, undergoing preliminary heating to raise its temperature. It then enters the spray device within the thickening tower 3 and is sprayed out. Specifically, the flue gas inlet of the thickening tower 3 is connected to the outlet flue of the dust collector, and its outlet is connected to the inlet flue of the desulfurization tower. The flue gas outlet, spray device, and inlet of the thickening tower 3 are arranged sequentially from top to bottom. The wastewater entering the thickening tower 3 is sprayed down by the spray device. Wastewater flows downwards, while flue gas at the dust collector outlet flue enters the thickening tower 3, then flows upwards from the inlet to the outlet and enters the desulfurization tower inlet flue. This allows the wastewater to come into countercurrent contact with the flue gas, increasing the heat exchange between the high-salt wastewater and the low-temperature flue gas, thus concentrating the wastewater. After the high-salt wastewater is heated once by the external heat exchanger 5, the initial temperature of the wastewater increases. Therefore, when it exchanges heat with the flue gas in the thickening tower 3, the water is more likely to turn into water vapor, resulting in a better concentration effect for the high-salt wastewater. Compared with the existing technology where all the flue gas enters the thickening tower 3 without preheating the high-salt wastewater, the water in the high-salt wastewater evaporates more easily. At the same time, compared with the existing technology, the unit load limit is lower, the wastewater treatment capacity is larger, and the concentration ratio is higher.
[0030] Furthermore, the flue gas temperature flowing from the SCR outlet flue to the evaporator 4 is approximately 350-380℃. After heat exchange with the wastewater in the evaporator 4, part of it enters the heat exchanger 5, while the other part returns directly to the dust collector inlet flue, where the flue gas temperature is approximately 180-220℃. After the flue gas passes through the dust collector for dust removal, the flue gas temperature entering the concentration tower 3 from the dust collector outlet flue is approximately 110-160℃. The high-salt wastewater is concentrated in the concentration tower 3, and finally enters the desulfurization tower inlet flue from the flue gas outlet at the top of the concentration tower 3, thus making cascade utilization of the waste heat of the flue gas and fully utilizing the waste heat of the flue gas for the concentration and evaporation of high-salt wastewater.
[0031] Specifically, a first pipe 7 connects the outlet of the high-salinity wastewater tank 1 and the inlet of the pretreatment system 2. A first pump 8 and a first electric valve 9 are sequentially installed on the first pipe 7 along the water flow direction, so that the wastewater in the high-salinity wastewater tank 1 can enter the pretreatment system 2 under the drive of the first pump 8, and the first electric valve 9 can control the water flow in the first pipe 7. A second pipe 10 connects the outlet of the pretreatment system 2 and the inlet of the thickening tower 3. A second pump 11 and a second electric valve 12 are sequentially installed on the second pipe 10 along the water flow direction, so that the treated wastewater in the pretreatment system 2 can enter the thickening tower 3 under the drive of the second pump 11, and the second electric valve 12 can control the water flow in the second pipe 10.
[0032] Specifically, a third pipe 13 connects the dust collector outlet flue and the flue gas inlet of the thickening tower 3. The third pipe 13 is equipped with an electric damper 14, a third electric valve 15 and a fan 16 in sequence along the flue gas flow direction. Thus, the flue gas from the dust collector outlet flue enters the thickening tower 3 under the action of the fan 16. The electric damper 14 is used to adjust the flow rate of the flue gas in the third pipe 13, and the third electric valve 15 is used to control the opening and closing of the third pipe 13.
[0033] Specifically, a fourth pipe 17 connects the concentrated wastewater tank to the first outlet of the concentration tower 3. A third pump 18 is installed on the fourth pipe 17, so that the concentrated wastewater in the concentration tower 3 enters the concentrated wastewater tank for temporary storage under the action of the third pump 18, and then enters the concentrated wastewater tank. A fifth pipe 19 connects the outlet of the concentrated wastewater tank to the inlet of the evaporation tower 4, and an atomizing water pump 20 is connected to the fifth pipe 19. So that the concentrated wastewater enters the evaporation tower 4 under the action of the atomizing water pump 20 and is sprayed out and comes into contact with the flue gas inside, causing the wastewater to evaporate and crystallize. Moreover, the atomizing water pump 20 is equipped with a frequency converter, so that the spraying water volume of the pump can be adjusted.
[0034] Specifically, the flue gas outlet of evaporator 4 is connected to a sixth pipe 21, which is connected to a fourth electric valve 22. A seventh pipe 23 connects the sixth pipe 21 to the flue gas inlet of heat exchanger 5, and a fifth electric valve 24 is installed on the seventh pipe 23. An eighth pipe 25 connects the sixth pipe 21 to the dust collector inlet flue. Thus, the flue gas from evaporator 4 enters the sixth pipe 21 and is then divided into two paths: one path enters the seventh pipe 23 and then the heat exchanger 5, while the other path enters the eighth pipe 25 and finally enters the dust collector inlet flue. The fourth electric valve 22 on the sixth pipe 21 controls the flow rate of the flue gas within the sixth pipe 21, thereby controlling the outflow rate and volume of the flue gas from evaporator 4, ensuring that the waste heat of the flue gas is fully utilized. The fifth electric valve 24 on the seventh pipe 23 controls the flow rate of the flue gas within the seventh pipe 23, thereby controlling the amount of flue gas entering the heat exchanger 5.
[0035] Below is a specific example:
[0036] The desulfurization system of a 2×330MW coal-fired power unit in Northwest China uses a wet desulfurization process, with a desulfurization wastewater volume of approximately 12m³. 3 The desulfurization wastewater has a suspended solids concentration of 8500 mg / L and a chloride ion concentration of 18700 mg / L per hour. The pretreatment system uses a triple-tank process. The desulfurization wastewater is pumped into the triple-tank treatment system via a wastewater buffer tank and a wastewater transfer pump. A high-efficiency flocculant is added to the triple-tank, resulting in a suspended solids concentration of 62 mg / L in the permeate. This permeate is then pumped to the concentration system via a clean water pump. The concentration system uses low-temperature flue gas concentration towers, with a one-tower-per-furnace design, consisting of two low-temperature concentration towers. Each concentration tower is equipped with a heat exchanger, with the heat source being the flue gas from the tail end of the bypass evaporator. When all the flue gas from the bypass evaporator returns to the dust collector inlet flue, the concentration tower receives 12 m³ of water. 3 / h, producing 3.5m 3 The concentrate is concentrated at a rate of 3.43 times in the bypass evaporator for evaporation and drying. Under the same unit combination operating conditions, when the flue gas at the tail end of the bypass evaporator is used as the heat source for the heat exchanger and for heat exchange with the circulating wastewater in the concentrate, the inlet water to the concentrate is 12m³. 3 / h, producing 2.6m 3 The concentration is concentrated to a bypass evaporator tower for evaporation and drying. The concentration tower has a concentration ratio of 4.62 times, which is 1.19 times higher than that of traditional low-temperature concentration.
[0037] The above examples also demonstrate that this system can significantly improve the concentration ratio of the concentration tower and reduce the wastewater treatment volume of the terminal evaporation and drying system.
[0038] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.
Claims
1. A zero-discharge system for high-salinity wastewater, characterized in that, It includes a high-salt wastewater pond, a pretreatment system, a concentration tower, a concentrated liquid wastewater pond, an evaporation tower, and a heat exchanger; The outlet of the high-salt wastewater tank, the pretreatment system, and the inlet of the concentration tower are connected in sequence. The first outlet of the concentration tower, the concentrated liquid wastewater pool, and the inlet of the evaporation tower are connected in sequence. The flue gas inlet of the evaporation tower is connected to the SCR outlet flue, and the flue gas outlet of the evaporation tower is connected to the dust collector inlet flue. The flue gas inlet, water inlet, and flue gas outlet of the evaporation tower are arranged from top to bottom. A circulating pump is connected to the second outlet of the concentration tower. The inlet of the heat exchanger is connected to the outlet of the circulating pump. The outlet is connected to the spray device at the top of the concentration tower. The flue gas inlet is connected to the flue gas outlet of the evaporation tower. The flue gas outlet is connected to the inlet flue of the dust collector. The inlet of the concentration tower is connected to the outlet flue of the dust collector, and its outlet is connected to the inlet flue of the desulfurization tower. The outlet, spray device and inlet of the concentration tower are arranged sequentially from top to bottom.
2. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, A first pipe connects the outlet of the high-salt wastewater tank and the inlet of the pretreatment system. A first pump and a first electric valve are sequentially installed on the first pipe along the water flow direction. A second pipe connects the outlet of the pretreatment system and the inlet of the concentration tower. The second pipe is equipped with a second pump and a second electric valve in sequence along the water flow direction.
3. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, A third pipe connects the dust collector outlet flue to the thickening tower inlet, and an electric damper, a third electric valve, and a fan are sequentially installed on the third pipe along the flue gas flow direction.
4. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, A fourth pipe connects the concentrated wastewater pool to the first outlet of the concentration tower, and a third pump is installed on the fourth pipe. A fifth pipe connects the outlet of the concentrated wastewater pool and the inlet of the evaporation tower. The fifth pipe is connected to an atomizing water pump, which is equipped with a frequency converter.
5. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, The evaporator's flue gas outlet is connected to a sixth pipe, which is connected to a fourth electric valve. A seventh pipe is connected between the sixth pipe and the heat exchanger's flue gas inlet, which is equipped with a sixth electric valve. The sixth pipe is connected to the dust collector's inlet flue.
6. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, The evaporation tower is equipped with an ash conveying system at its outlet.
7. The zero-discharge system for high-salinity wastewater according to claim 1, characterized in that, The pretreatment system may be one or more of a triplet tank, a sedimentation tank, or a mechanically accelerated stirring clarification tank.