Wastewater distillation crystallization apparatus

Abstract

The present application relates to wastewater treatment technical field and disclose a kind of wastewater distillation crystallization device, including pretreatment component, pretreatment component is used to pretreat wastewater;Membrane distillation concentration component, membrane distillation concentration component includes shell and be located in the hydrophobic hollow fiber membrane of shell, the space in shell is separated into hot side flow channel and cold side flow channel by hydrophobic hollow fiber membrane, hot side flow channel has the import for receiving the wastewater after pretreatment, hot side flow channel also has the concentrated liquid outlet for discharging the wastewater after distillation, cold side flow channel has the import for receiving cooling medium, the outlet of pretreatment component is connected with the import of hot side flow channel, membrane distillation concentration component is used to distill wastewater;Crystallization separation component, the concentrated liquid outlet of membrane distillation concentration component is connected with the import of crystallization separation component.The present application can complete the concentration and crystallization separation of wastewater in the same device, solve the problem that membrane distillation equipment can only concentrate in the related art but cannot complete solidification separation in situ.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically relates to a wastewater distillation and crystallization apparatus. Background Technology

[0002] In related technologies, the urea hydrolysis process for ammonia production in coal-fired power plants intermittently generates small-flow, high-ammonia-nitrogen wastewater. The industry's mainstream high-flow-rate wastewater zero-discharge equipment is incompatible with the condition of this wastewater's trace and intermittent production, resulting in low equipment utilization, high energy consumption, and overall high treatment costs. Conventional membrane distillation equipment can only complete the wastewater concentration process and lacks a matching integrated crystallization separation structure. The concentrated high-salt water cannot be solidified and separated on-site and still needs to be transported to other sites for secondary treatment, failing to achieve near-zero wastewater discharge. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention provide a wastewater distillation crystallization apparatus that can complete wastewater concentration and crystallization separation within the same apparatus, achieving near-zero discharge.

[0004] The wastewater distillation crystallization apparatus of this disclosure includes:

[0005] Pretreatment component, the pretreatment component being used for pretreatment of wastewater; A membrane distillation concentration unit includes a housing and a hydrophobic hollow fiber membrane disposed within the housing. The hydrophobic hollow fiber membrane divides the space within the housing into a hot-side channel and a cold-side channel. The hot-side channel has a first inlet for receiving pretreated wastewater and a concentrated liquid outlet for discharging the distilled wastewater. The cold-side channel has a second inlet for receiving a cooling medium. The outlet of the pretreatment unit is connected to the first inlet of the hot-side channel. The membrane distillation concentration unit is used for distilling wastewater. The crystallization separation component has its concentrate outlet connected to the inlet of the crystallization separation component.

[0006] The wastewater distillation crystallization apparatus of this disclosure, through the arrangement of a pretreatment component, a membrane distillation concentration component, and a crystallization separation component, allows wastewater to enter the membrane distillation concentration component after impurities are removed by the pretreatment component. Driven by the vapor pressure difference across the hydrophobic hollow fiber membrane, distillation and concentration are completed. The concentrated liquid then enters the crystallization separation component for further evaporation and crystallization. Thus, a complete treatment chain from wastewater pretreatment to concentration and then to crystallization separation is realized in the same device, solving the problem in related technologies that membrane distillation equipment can only concentrate but cannot complete solidification and separation on-site, achieving near-zero wastewater discharge.

[0007] In some embodiments, the wastewater distillation crystallization apparatus further includes a mobile support component, on which the pretreatment component, the membrane distillation concentration component, and the crystallization separation component are all mounted.

[0008] The wastewater distillation crystallization apparatus of this disclosure integrates the pretreatment component, membrane distillation concentration component, and crystallization separation component into a single movable module by setting up a mobile support component. This allows the apparatus to be moved and shared between multiple wastewater discharge points, avoiding redundant investment caused by configuring separate treatment facilities for each discharge point and improving equipment utilization.

[0009] In some embodiments, the cold-side flow channel also has a plurality of outlets for discharging cooling medium, one of which is located at the top of the housing and another of which is located at the bottom of the housing.

[0010] The wastewater distillation crystallization apparatus of this disclosure provides outlets at the top and bottom of the outer shell. After the cooling medium enters the cold side flow channel from the second inlet, it can be discharged from the top and bottom outlets. This allows the cooling medium to form a more uniform flow distribution in the cold side flow channel, improving heat exchange efficiency. It also facilitates flexible selection of the inlet and outlet pipeline arrangement of the cooling medium according to the actual installation space.

[0011] In some embodiments, the pretreatment component includes a filter and an inlet tank connected in sequence, the filter being used to receive wastewater, the outlet of the filter being connected to the inlet tank, and the inlet tank being connected to a first inlet of the hot-side flow channel.

[0012] The wastewater distillation crystallization apparatus of this disclosure, through the setting of a filter and an inlet tank, allows the filter to trap suspended particulate matter in the wastewater, preventing blockage of the hydrophobic hollow fiber membrane in the subsequent membrane distillation concentration component, while the inlet tank provides a buffer space for intermittently discharged wastewater, enabling the subsequent treatment process to operate stably in batches.

[0013] In some embodiments, the pretreatment component includes a pH adjustment tank for adjusting the pH value of the wastewater.

[0014] The wastewater distillation crystallization apparatus of this disclosure, by setting up a pH adjustment tank, can adjust the pH value of the wastewater to a suitable range before it enters the membrane distillation concentration unit, thereby reducing the volatilization of ammonia across the membrane during the distillation process, reducing the ammonia nitrogen content in the product water, and also reducing the corrosion of the equipment.

[0015] In some embodiments, the wastewater distillation crystallization apparatus further includes a heat exchanger disposed in the flow path between the outlet of the pretreatment component and the first inlet of the hot-side flow channel, the heat exchanger being used to exchange heat with an external waste heat source to heat the wastewater.

[0016] The wastewater distillation crystallization apparatus of this disclosure, through the setting of a heat exchanger, can utilize external waste heat to heat the wastewater to reach the temperature required for membrane distillation, without the need for a separate electric heater or boiler, thus significantly reducing operating energy consumption and costs.

[0017] In some embodiments, the crystallization separation assembly includes a crystallization tank and a stirrer disposed within the crystallization tank. The crystallization tank has a conical bottom, and a discharge port is provided at the lower end of the conical bottom for discharging crystal slurry.

[0018] The wastewater distillation crystallization apparatus of this disclosure, through the setting of a crystallization tank and a stirrer, allows the concentrate produced by membrane distillation to be further evaporated and concentrated in the crystallization tank until it becomes supersaturated and crystallized salt is precipitated. The stirring of the stirrer can prevent local supersaturation and agglomeration, promote uniform crystallization, and the conical bottom is conducive to the aggregation and discharge of crystal slurry.

[0019] In some embodiments, the wastewater distillation crystallization apparatus further includes a product water tank connected to the outlet.

[0020] The wastewater distillation crystallization apparatus of this disclosure, by connecting the product water tank to the outlet, allows the cooling medium discharged from the cold side flow channel to enter the product water tank for collection, facilitating the temporary storage and recycling of the cooling medium. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the membrane distillation concentration assembly in this invention.

[0022] Figure 2 This is a schematic diagram of the overall structure of the present invention.

[0023] Figure label: 1. Pretreatment components; 11. Filter; 12. Inlet tank; 13. pH adjustment tank; 2. Membrane distillation concentration unit; 21. Outer shell; 22. Hydrophobic hollow fiber membrane; 23. Hot side channel; 231. First inlet; 232. Concentrate outlet; 24. Cold side channel; 241. Second inlet; 242. Outlet; 3. Crystallization separation components; 31. Crystallization tank; 32. Stirrer; 4. Water production tank. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] The wastewater distillation crystallization apparatus of this disclosure can be applied to the treatment of wastewater from urea hydrolysis for ammonia production in coal-fired power plants. It is used to concentrate and crystallize intermittently generated, low-flow-rate, high-ammonia-nitrogen wastewater to achieve near-zero discharge. Of course, this wastewater distillation crystallization apparatus can also be applied to other scenarios requiring wastewater reduction and resource recovery through distillation concentration and crystallization separation.

[0026] like Figure 1 and Figure 2 As shown, the wastewater distillation crystallization apparatus of this embodiment includes a pretreatment component 1, a membrane distillation concentration component 2, and a crystallization separation component 3.

[0027] The pretreatment component 1 is used to pretreat wastewater. The membrane distillation concentration component 2 includes a housing 21 and a hydrophobic hollow fiber membrane 22 disposed within the housing 21. The hydrophobic hollow fiber membrane 22 divides the space within the housing 21 into a hot-side channel 23 and a cold-side channel 24. The hot-side channel 23 has a first inlet 231 for receiving pretreated wastewater and a concentrated liquid outlet 232 for discharging distilled wastewater. The cold-side channel 24 has a second inlet 241 for receiving a cooling medium. The outlet of the pretreatment component 1 is connected to the first inlet 231 of the hot-side channel 23. The membrane distillation concentration component 2 is used to distill wastewater. The concentrated liquid outlet 232 of the membrane distillation concentration component 2 is connected to the inlet of the crystallization separation component 3.

[0028] The wastewater distillation crystallization apparatus of this embodiment, through the arrangement of a pretreatment component 1, a membrane distillation concentration component 2, and a crystallization separation component 3, allows wastewater to enter the membrane distillation concentration component 2 after the pretreatment component 1 removes suspended solids and other impurities. Driven by the vapor pressure difference across the hydrophobic hollow fiber membrane 22, distillation and concentration are completed. The concentrated liquid then enters the crystallization separation component 3 for further evaporation and crystallization. Thus, a complete treatment chain from wastewater pretreatment to concentration and then to crystallization separation is realized in the same device, solving the problem in related technologies that membrane distillation equipment can only concentrate but cannot complete solidification and separation on-site.

[0029] In some embodiments, the wastewater distillation crystallization apparatus further includes a mobile support component, on which the pretreatment component 1, the membrane distillation concentration component 2, and the crystallization separation component 3 are all mounted.

[0030] The wastewater distillation crystallization apparatus of this disclosure integrates the pretreatment component 1, the membrane distillation concentration component 2, and the crystallization separation component 3 into a single movable module by setting up a mobile support component. This allows the apparatus to be moved and shared between multiple wastewater discharge points, avoiding redundant investment caused by configuring treatment facilities separately for each discharge point and improving equipment utilization.

[0031] Specifically, the mobile load-bearing components can be containers or skid-mounted platforms, with forklift slots and lifting points at the bottom for easy transport and on-site deployment. Containers can be standard 20-foot containers or smaller custom-made containers, with all processing units integrated inside the container. Only quick-connect interfaces for heat sources, cooling water, and power are required on the outside for plug-and-play operation.

[0032] In some embodiments, the cold side channel 24 further has a plurality of outlets 242 for discharging cooling medium, one outlet 242 being disposed at the top of the housing 21 and another outlet 242 being disposed at the bottom of the housing 21.

[0033] The wastewater distillation crystallization apparatus of this embodiment provides outlets 242 at the top and bottom of the outer shell 21. After the cooling medium enters the cold side flow channel 24 from the second inlet 241, it can be discharged from the outlets 242 at the top and bottom. This allows the cooling medium to form a more uniform flow distribution in the cold side flow channel 24, improving the heat exchange efficiency. It also facilitates the flexible selection of the inlet and outlet pipeline arrangement of the cooling medium according to the actual installation space.

[0034] In some embodiments, the wastewater distillation crystallization apparatus further includes a product water tank 4, which is connected to an outlet 242.

[0035] The wastewater distillation crystallization apparatus of this embodiment connects the product water tank 4 to the outlet 242, allowing the cooling medium discharged from the cold side flow channel 24 to enter the product water tank 4 for collection, facilitating the temporary storage and recycling of the cooling medium.

[0036] Specifically, when the membrane distillation concentration unit 2 adopts the direct contact membrane distillation mode, the cooling medium comes into direct contact with water vapor in the cold side channel 24. After the water vapor condenses, it mixes with the cooling medium and is discharged from the outlet 242 into the product water tank 4. An online conductivity monitor can be installed in the product water tank 4 to monitor the product water quality in real time. The qualified product water can be reused for power plant circulating cooling water makeup or demineralized water system.

[0037] In some embodiments, the pretreatment component 1 includes a filter 11 and an inlet tank 12 connected in sequence. The filter 11 is used to receive wastewater, and the outlet of the filter 11 is connected to the inlet tank 12. The inlet tank 12 is connected to the first inlet 231 of the hot side flow channel 23.

[0038] The wastewater distillation crystallization apparatus of this embodiment, through the arrangement of filter 11 and inlet tank 12, the filter 11 can intercept suspended particulate matter in the wastewater and prevent the hydrophobic hollow fiber membrane 22 of the subsequent membrane distillation concentration component 2 from becoming clogged, while the inlet tank 12 provides a buffer space for intermittently discharged wastewater, so that the subsequent treatment process can operate stably in batches.

[0039] Specifically, filter 11 can be a security filter with a filter element precision of 5μm and a stainless steel shell, which can effectively ensure that the pollution index of the wastewater entering the membrane distillation concentration module 2 meets the requirements. The inlet tank 12 is equipped with a liquid level sensor to detect the liquid level in the tank. When the liquid level reaches the preset value, a processing batch is automatically started to match the intermittent drainage cycle of the power plant.

[0040] In some embodiments, the pretreatment component 1 includes a pH adjustment tank 13 for adjusting the pH value of the wastewater.

[0041] The wastewater distillation crystallization apparatus of this embodiment can adjust the pH value of the wastewater to a suitable range before it enters the membrane distillation concentration component 2 by setting the pH adjustment tank 13, thereby reducing the volatilization of ammonia across the membrane during the distillation process, reducing the ammonia nitrogen content in the product water, and also reducing the corrosion of the equipment.

[0042] Specifically, the pH adjustment tank 13 can be installed in the flow path between the filter 11 and the inlet tank 12, or in the flow path between the inlet tank 12 and the membrane distillation concentration component 2. Dilute sulfuric acid or other acidic agents can be added to the pH adjustment tank 13. The dosage is monitored and automatically controlled by an online pH meter to adjust the pH value of the wastewater to a neutral to slightly acidic range of 6-8.

[0043] In some embodiments, the wastewater distillation crystallization apparatus further includes a heat exchanger disposed on the flow path between the outlet of the pretreatment component 1 and the first inlet 231 of the hot side flow channel 23. The heat exchanger is used to exchange heat with an external waste heat source to heat the wastewater.

[0044] The wastewater distillation crystallization apparatus of this disclosure, through the setting of a heat exchanger, can utilize the existing low-temperature waste heat of the power plant (such as circulating cooling water, flue gas waste heat or low-pressure steam) to heat the wastewater to the temperature required for membrane distillation, without the need for a separate electric heater or boiler, thus significantly reducing operating energy consumption and costs.

[0045] Specifically, the heat exchanger can be a plate heat exchanger, and the heat exchange area is determined according to the amount of water to be treated and the temperature rise requirement. The primary side of the heat exchanger is connected to an external waste heat source, and the secondary side is connected to the wastewater flow path. The wastewater is heated to 60~80℃ and then sent into the hot side flow channel 23 of the membrane distillation concentration module 2.

[0046] In some embodiments, the crystallization separation component 3 includes a crystallization tank 31 and a stirrer 32 disposed in the crystallization tank 31. The crystallization tank 31 has a conical bottom, and a discharge port is provided at the lower end of the conical bottom for discharging crystal slurry.

[0047] In the wastewater distillation crystallization apparatus of this embodiment, the concentrated liquid produced by membrane distillation is further evaporated and concentrated in the crystallization tank 31 until it becomes supersaturated and crystallized salt is precipitated. The stirring of the stirrer 32 can prevent local supersaturation and agglomeration, promote uniform crystallization, and the conical bottom is conducive to the aggregation and discharge of crystal slurry.

[0048] Specifically, the effective volume of the crystallization tank 31 can be determined according to the amount of water to be treated. The outer wall of the crystallization tank 31 can be fitted with a jacket or coil to allow the flow of a waste heat medium to heat and evaporate the solution inside. The speed of the agitator 32 is adjustable to meet the stirring intensity requirements of different crystallization stages. The discharge port is located at the lower end of the conical bottom and is equipped with a valve for periodically discharging the crystal slurry. The discharged crystal slurry can be further separated by a centrifuge or filter press to obtain crystalline salt and a small amount of mother liquor. The mother liquor can be returned to the crystallization tank 31 for further evaporation.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0054] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A wastewater distillation crystallization apparatus, characterized in that, include: A pretreatment component (1) is used to pretreat wastewater; A membrane distillation concentration assembly (2) includes a housing (21) and a hydrophobic hollow fiber membrane (22) disposed within the housing (21). The hydrophobic hollow fiber membrane (22) divides the space within the housing (21) into a hot-side channel (23) and a cold-side channel (24). The hot-side channel (23) has a first inlet (231) for receiving pretreated wastewater and a concentrated liquid outlet (232) for discharging distilled wastewater. The cold-side channel (24) has a second inlet (241) for receiving a cooling medium. The outlet of the pretreatment assembly (1) is connected to the first inlet (231) of the hot-side channel (23). The membrane distillation concentration assembly (2) is used for distilling wastewater. The crystallization separation component (3) has its concentrate outlet (232) connected to the inlet of the crystallization separation component (3).

2. The wastewater distillation crystallization apparatus according to claim 1, characterized in that, It also includes a mobile carrier assembly, on which the pretreatment assembly (1), the membrane distillation concentration assembly (2) and the crystallization separation assembly (3) are all mounted.

3. The wastewater distillation crystallization apparatus according to claim 1, characterized in that, The cold side flow channel (24) also has a plurality of outlets (242) for discharging cooling medium, one of which is located at the top of the housing (21) and the other of which is located at the bottom of the housing (21).

4. The wastewater distillation crystallization apparatus according to claim 1, characterized in that, The pretreatment component (1) includes a filter (11) and an inlet tank (12) connected in sequence. The filter (11) is used to receive wastewater. The outlet of the filter (11) is connected to the inlet tank (12). The inlet tank (12) is connected to the first inlet (231) of the hot side flow channel (23).

5. The wastewater distillation crystallization apparatus according to claim 4, characterized in that, The pretreatment component (1) includes a pH adjustment tank (13) for adjusting the pH value of the wastewater.

6. The wastewater distillation crystallization apparatus according to claim 1, characterized in that, It also includes a heat exchanger located in the flow path between the outlet of the pretreatment component (1) and the first inlet (231) of the hot side flow channel (23), the heat exchanger being used to exchange heat with an external waste heat source to heat the wastewater.

7. The wastewater distillation crystallization apparatus according to claim 1, characterized in that, The crystallization separation component (3) includes a crystallization tank (31) and a stirrer (32) disposed in the crystallization tank (31). The crystallization tank (31) has a conical bottom and a discharge port is provided at the lower end of the conical bottom for discharging crystal slurry.

8. The wastewater distillation crystallization apparatus according to claim 3, characterized in that, It also includes a water production tank (4), and an outlet (242) connected to the water production tank (4).

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