Method for the treatment of dyeing wastewater by freeze concentration and device therefor

Abstract

The present application relates to a method and device for treating dye wastewater by freeze concentration, the method comprising the following steps: S1, dye wastewater in a waste liquid tank is sent to a pre-cooling device, heat exchange is carried out in the pre-cooling device, preliminary cooling is realized, and the dye wastewater without ice in the pre-cooling device is sent to a reaction kettle through a discharge pipe. The present application realizes the efficiency of continuous concentration of dye wastewater and the rapidity of the treatment process through a dye wastewater pre-cooling device, a freeze concentration device and a melting device, ice crystals are continuously generated on each layer of the cooling surface until a single large ice crystal is formed, the large ice single crystal contains a small amount of solutes and impurities, therefore, compared with ice crystals produced by other freeze concentration devices, the large ice crystals produced by progressive freeze concentration have higher purity, in addition, the single ice crystal will make the ice crystals more easily separated from the main solution, thereby ensuring lower maintenance and operation costs.

Description

Technical Field

[0001] This invention relates to the field of dye wastewater treatment technology, and in particular to a method and apparatus for freeze-concentrating dye wastewater. Background Technology

[0002] Due to the toxicity and high salinity of dyes, dye wastewater has become one of the most challenging types of industrial wastewater. During dye synthesis, the introduction of inorganic salts for salting out dye products inevitably produces saline dye wastewater. Therefore, typical textile wastewater often has excessively high salinity, which can harm microbial growth and human health. The dye industry uses water as a solvent and discharges large amounts of wastewater through multiple processes. The basic raw materials for dye intermediate production are organic compounds such as benzene and naphthalene, which are highly toxic, resulting in wastewater with high color intensity. Currently, the main methods for treating dye wastewater include physicochemical, chemical, and biochemical methods. Many scholars have proposed that for high-concentration, high-salt organic intermediate production wastewater, a suitable physicochemical process can be selected as a pretreatment method, combined with biological treatment. There are two pretreatment options: evaporation concentration and freeze concentration. Compared to evaporation concentration, freeze concentration consumes only 1 / 6 of the energy, and is safer with a longer equipment lifespan.

[0003] Freezing concentration is a novel water treatment technology that utilizes the physical phase change of water molecules at temperatures below freezing to recover pure water and concentrate pollutants. It's a new technology for treating high-salinity wastewater and obtaining pure water and high-purity salt. Its main principle is based on the physical property that the freezing point of impurities in wastewater is lower than that of water. In a low-temperature environment, water crystallizes out as a solid phase first, while impurities remain in the concentrate as a liquid phase. The solid and liquid phases are then separated by centrifugation, filtration, and other methods. Freezing concentration is divided into three categories: progressive freezing concentration, block freezing concentration, and suspension freezing concentration. Suspension freezing concentration is the most traditional freezing concentration method. Its process can be divided into four stages: feed crystallization, feed recrystallization, ice crystal washing, and recycling. Due to its complexity and high requirements for equipment operation, suspension freezing concentration is the most expensive compared to other concentration methods. The freezing process requires careful control of various parameters, such as supercooling; otherwise, secondary nucleation of ice crystals can occur, leading to an excessively high ice crystal entrainment rate. Suspension crystallization freeze-concentration produces smaller ice crystals and a larger solid-liquid interface, making separation of ice crystals from the feed liquid difficult. Furthermore, the higher the viscosity of the concentrated feed liquid, the more difficult the ice crystal separation becomes. In block freeze-concentration, the liquid solution is completely frozen, and then partially thawed to recover the concentrated liquid. The concentrated portion is then separated from the ice by gravity. Block freeze-concentration produces ice crystals with lower purity, resulting in lower separation efficiency compared to other freeze-concentration methods. Based on this, this invention develops a different method and apparatus for progressive freeze-concentration treatment of dye wastewater. Summary of the Invention

[0004] Therefore, it is necessary to provide a method and apparatus for freeze-concentrating dye wastewater to address the problem of difficulty in separating ice crystals from mother liquor in existing technologies, which leads to low concentration efficiency.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a method for freeze-concentrating dye wastewater, comprising the following steps:

[0006] Step S1: Send the dye wastewater in the waste liquid tank into the pre-cooling device. The dye wastewater undergoes heat exchange in the pre-cooling device to achieve preliminary cooling. The unfrozen dye wastewater sent into the pre-cooling device is sent into the reaction vessel through the discharge pipe.

[0007] Step S2: After the dye wastewater is fed into the reactor, the constant temperature device maintains the cold field of the reactor; the ice generated by freezing grows on the cooling stirring rod in the reactor to form ice columns, thereby achieving the initial concentration of dye wastewater and separation of ice crystals.

[0008] Step S3: Turn on the ice melting device, move the ice column on the cooling stirring rod into the ice melting device, wash and break the ice in sequence, and the broken ice falls to the bottom of the ice melting device to melt and be collected for use.

[0009] Steps S1 and S3 are repeated cyclically, and finally the remaining concentrate is discharged from the reactor.

[0010] As a preferred example, in step S2, the remaining unfrozen concentrate flows from the reactor into the insulation tank by gravity, and the concentrate sent into the insulation tank is pumped back into the reactor for mixing and then frozen again; this process is repeated cyclically.

[0011] An apparatus for freeze-concentrating dye wastewater, employing the freeze-concentration method for treating dye wastewater as described above, the apparatus comprising:

[0012] Waste liquid tank;

[0013] A cryogenic concentration apparatus includes a reaction vessel, a cooling and stirring mechanism, and a temperature control device. The reaction vessel is connected to the waste liquid tank. The cooling and stirring mechanism is detachably installed inside the reaction vessel. The temperature control device is connected to the cooling and stirring mechanism to enable the cooling and stirring mechanism to maintain a low temperature.

[0014] An ice-melting device includes a housing, a conveying mechanism, and an ice-crushing mechanism. The ice-crushing mechanism is disposed inside the housing, and the conveying mechanism is used to move the cooling and stirring mechanism into the housing.

[0015] As a preferred embodiment, a precooling device is also included, which is disposed between the waste liquid tank and the reaction vessel for precooling the dye wastewater entering the reaction vessel.

[0016] As a preferred example, the cooling and stirring mechanism includes:

[0017] A cooling stirring rod is disposed inside the reaction vessel. The cooling stirring rod includes a cooling sleeve and a stirring rod. The stirring rod is rotatably sleeved inside the cooling sleeve. The bottom of the stirring rod extends outside the cooling sleeve and is fixedly connected to multiple stirring paddles.

[0018] A CNC motor is detachably connected to the outside of the reaction vessel, and its rotating shaft is fixedly connected to the stirring rod to drive the stirring rod to rotate.

[0019] As a preferred example, the temperature control device has a coolant circulating inside, and the temperature control device is connected to the cooling jacket.

[0020] As a preferred example, the outer wall of the reactor is provided with a jacket, and the temperature control device is connected to the jacket.

[0021] As a preferred example, the reactor is connected to an insulation tank, and the insulation tank is also equipped with a drain pipe for reconnecting with the reactor to form a closed-loop pipeline.

[0022] As a preferred example, the drain pipe on the heat preservation tank is equipped with a discharge flow meter.

[0023] As a preferred example, the ice-melting device further includes a water storage tank and a washer, the water storage tank being connected to the washer, and the washer being fixedly connected to the upper opening of the housing.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) This invention achieves high efficiency and rapid processing of dye wastewater through a dye wastewater pre-cooling device, a freeze concentration device, and a melting device. Progressive freeze concentration is a form of freeze concentration that continuously produces ice crystals at each layer on the cooling surface until a single large ice crystal is formed. These large ice crystals contain less solute and impurities, thus resulting in higher purity ice crystals compared to those produced by other freeze concentration devices. Furthermore, the presence of single ice crystals makes them easier to separate from the main solution, ensuring lower maintenance and operating costs.

[0026] (2) The icing system designed in this invention achieves dynamic icing, improving the treatment efficiency of dye wastewater. This invention develops a different progressive freeze-concentration device design, which is a crystallizer with a cooling stirring rod as the main component, providing optimal flow characteristics for the solution while improving heat transfer and solute diffusion. By changing the coolant temperature and stirring rate, the heat transfer between the solution and the coolant is increased, thereby improving the concentration performance.

[0027] (3) The present invention solves the problem of rapid and efficient separation of highly concentrated liquid from ice by directly extracting large ice crystals from dye wastewater. The energy recovery system, such as the pre-cooling device and waste liquid tank, realizes the recovery of the cold energy of ice melt water and highly concentrated wastewater, thereby achieving energy-saving operation of the device. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure in Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure in Embodiment 2 of the present invention;

[0030] Figure 3 This is a schematic diagram of the structure in Embodiment 3 of the present invention;

[0031] Figure 4 This is a schematic diagram of the structure in Embodiment 4 of the present invention;

[0032] Figure 5 This is a schematic diagram showing the installation of the reaction vessel and the cooling and stirring mechanism;

[0033] Figure 6 Effect of stirring rate on salt removal efficiency (a) and COD concentration efficiency (b) at different coolant temperatures (freezing time: 60 min);

[0034] Figure 7 The effect of coolant temperature on salt removal efficiency (a) and COD concentration efficiency (b) at different ice formation rates (stirring speed: 300 r / min).

[0035] Figure 8 , Figure 9 Response surface contour plot showing the effect of the interaction between the two factors on salt removal efficiency;

[0036] Figure 10 , Figure 11 The response surface contour plot shows the effect of the interaction between the two factors on COD concentration efficiency.

[0037] In the diagram: 1-Waste liquid tank, 2-Pre-cooling device, 3-Heat exchanger, 4-Freezing concentration device, 5-Constant temperature device, 6-CNC motor, 7-Cooling stirring rod, 71-Cooling jacket, 72-Stirring paddle, 8-Reaction vessel, 81-Mounting plate, 82-Opening, 9-Insulated tank, 10-Ice melting device, 11-Conveying mechanism, 12-Shell, 13-Water storage tank, 14-Scrubber, 15-Third discharge pump, 16-Ice crushing mechanism, 17-First discharge valve, 18-First discharge pump, 19-Second discharge valve, 20-Second discharge pump, 21-Third discharge valve, 22-Fourth discharge valve, 23-Discharge flow meter. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0040] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] Please see Figure 1 The diagram below is a schematic diagram of the structural system of the present invention. The method for freeze-concentrating dye wastewater according to an embodiment of the present invention will now be described: A method for freeze-concentrating dye wastewater includes the following steps:

[0043] Step S1: Send the dye wastewater in waste liquid tank 1 into pre-cooling device 2. The dye wastewater undergoes heat exchange in pre-cooling device 2 to achieve preliminary cooling. The unfrozen dye wastewater sent into pre-cooling device 2 is sent into reaction vessel 8 through discharge pipe.

[0044] Step S2: After the dye wastewater is fed into the reactor 8, the constant temperature device 5 maintains the cold field of the reactor 8; the ice generated by freezing grows on the cooling stirring rod 7 in the reactor 8 to form ice columns, thereby achieving the initial concentration of dye wastewater and separation of ice crystals.

[0045] In this step, the remaining unfrozen concentrate flows from the reactor 8 into the insulation tank 9 by gravity. The concentrate in the insulation tank 9 is then pumped back into the reactor 8 for mixing and then frozen again. This process is repeated in a cycle.

[0046] Step S3: Turn on the ice melting device 10, move the ice column on the cooling stirring rod 7 into the ice melting device 10, wash and break the ice in sequence, and the broken ice falls to the bottom of the ice melting device 10 to melt and be collected for use.

[0047] Steps S1 and S3 are repeated cyclically, and the remaining concentrate is discharged from reactor 8.

[0048] The above-described method for treating dye wastewater by freezing and concentration relies on the apparatus for treating dye wastewater by freezing and concentration proposed in this invention. This apparatus for treating dye wastewater by freezing and concentration is also the focus of protection in this application. The apparatus for treating dye wastewater by freezing and concentration will be described in detail below:

[0049] Example 1

[0050] Please combine Figure 1 and Figure 5 As shown, an apparatus for freezing and concentrating dye wastewater includes: a waste liquid tank 1, a freezing and concentrating device 4, and an ice-melting device 10. The waste liquid tank 1 is used for transferring and storing dye wastewater in the dye factory and for conveying dye wastewater to subsequent equipment through a pipeline, which is equipped with a first discharge valve 17 and a first discharge pump 18.

[0051] The cryogenic concentration unit 4 includes a reaction vessel 8, a cooling and stirring mechanism, and a temperature control device 5. The cooling and stirring mechanism includes a cooling stirring rod 7 and a CNC motor 6. Specifically, the reaction vessel 8 is connected to the waste liquid tank 1 via a pipeline. The reaction vessel 8 is a double-jacketed reaction vessel, and its jacket is connected to the temperature control device 5. Coolant circulates inside the temperature control device 5. This circulating coolant flows through the jacket of the reaction vessel 8: the low-temperature coolant enters from the lower inlet of the reaction vessel 8 and returns to the temperature control device 5 through the upper outlet of the reaction vessel 8. The low-temperature coolant exchanges heat with the dye wastewater in the reaction vessel 8 to achieve a low temperature inside the reaction vessel 8. The temperature control device 5 has its own refrigeration compressor and a liquid pump to drive the coolant circulation, or it is connected to an external cold source to drive the coolant to circulate between the reaction vessel 8 and the external cold source.

[0052] The cooling and stirring mechanism is detachably installed inside the reaction vessel 8. In this embodiment, please refer to [link to relevant documentation]. Figure 5This is a schematic diagram of the installation of the reactor and the cooling and stirring mechanism. The cooling and stirring mechanism includes: a mounting plate 81, a cooling stirring rod 7, and a CNC motor 6. The mounting plate 81 is square or rectangular. A mounting groove matching the mounting plate 81 is opened at the middle of the top of the reactor 8. An opening 82 is opened at the middle of the mounting groove for the cooling stirring rod 7 to enter and exit the reactor 8. A step is formed between the mounting groove and the opening 82 to support the mounting plate 81 and prevent the mounting plate 81 from rotating during operation.

[0053] The cooling stirring rod 7 includes a cooling sleeve 71 and a stirring rod. The top of the cooling sleeve 71 is fixedly connected to the middle of the bottom of the mounting plate 81. The cooling sleeve 71 is also connected to the constant temperature device 5 through a pipeline to form a low temperature, and its working principle is the same as that of the reaction vessel 8 described above. The stirring rod is rotatably fitted inside the cooling sleeve 71. The bottom of the stirring rod extends outside the cooling sleeve 71 and is fixedly connected to multiple stirring paddles 72. The top extends through to the outside of the mounting plate 81. The stirring rod and stirring paddles 72 can rotate to provide fluidity for the dye wastewater and achieve a dynamic freezing effect. It should be noted that the outer diameter of the cooling sleeve 71 and stirring paddles 72 when rotating needs to be smaller than the size of the opening 82 to prevent the cooling stirring rod 7 from being unable to be removed from the reaction vessel 8.

[0054] The CNC motor 6 is fixedly connected to the mounting plate 81 and can be detachably connected to the top of the reactor 8 via the mounting plate 81. Its rotating shaft is fixedly connected to the top of the stirring rod via a coupling, and is used to drive the stirring rod to rotate and control the speed.

[0055] The ice-melting device 10 includes a housing 12, a conveying mechanism 11, and an ice-crushing mechanism 16. The ice-crushing mechanism 16 is disposed inside the housing 12, and the conveying mechanism 11 is used to move the cooling and stirring mechanism into the housing 12. Specifically, the housing 12 is disposed on one side of the reactor 8 or stacked directly above the reactor 8. When the cooling jacket 71 is covered with ice columns, the conveying mechanism 11 lifts the entire cooling and stirring mechanism and transports it into the housing 12 for ice crushing to accelerate melting. Specifically, several lifting lugs are fixedly connected to the top of the mounting plate 81. The conveying mechanism 11 lifts the mounting plate 81 from the mounting groove through the lifting lugs until the stirring paddle 72 also comes out from the opening 82, and then sends the entire cooling and stirring mechanism into the housing 12. If the housing 12 and the reactor 8 are arranged side by side, the conveying mechanism 11 also includes facilities such as a ceiling track, which moves laterally a certain distance before sending the cooling and stirring mechanism into the reactor 8. If the housing 12 and the reactor 8 are stacked vertically, the cooling and stirring mechanism can be directly lifted into the housing 12.

[0056] The cooling jacket 71, which is fed into the housing 12, is covered with ice columns. At this time, the ice columns are broken by the ice-crushing mechanism 16. The broken ice columns fall from the cooling jacket 71 and melt, while the cooling stirring mechanism is restored and returned to the reaction vessel 8 for refreezing and concentration. In this ice-melting device 10, the conveying mechanism 11 and the ice-crushing mechanism 16 can be purchased from existing equipment. For example, the conveying mechanism 11 can be a gantry crane, a crane, or non-standard parts such as pulley blocks. The ice-crushing mechanism 16 can be an ice shaving machine, an impact drill, or non-standard parts such as blades and water flushing. The specific structure, equipment, and model of the above mechanisms are not limited, as long as they can achieve the effect required by this invention.

[0057] Example 2

[0058] The components and structure described above remain unchanged; please refer to [link / reference]. Figure 2 This embodiment adds a precooling device 2, which is a tank with a top opening 82 connected to the waste liquid tank 1. A first discharge valve 17 and a first discharge pump 18 for feeding dye wastewater are installed between the outlet of the waste liquid tank 1 and the inlet of the precooling device 2. A second discharge valve 19 and a second discharge pump 20 are installed between the outlet of the precooling device 2 and the inlet of the reactor 8, and both have an anti-backflow function to prevent cross-contamination of waste liquid. The precooling device 2 is equipped with a heat exchanger 3. The cold source can be crushed ice from the ice column or an external cold source, used to precool the dye wastewater entering the reactor 8, so that the dye wastewater is cooled to the target temperature of 4°C on its cooling surface, thereby reducing the supercooling between the dye wastewater and the reactor 8 during subsequent freeze concentration.

[0059] Example 3

[0060] The components and structures described in Embodiments 1 and 2 remain unchanged; please refer to [link / reference]. Figure 3 This embodiment also adds a heat preservation tank 9. The inner bottom of the reactor 8 is funnel-shaped, and a discharge pipe is connected between it and the top opening 82 of the heat preservation tank 9. This allows the concentrated wastewater in the reactor 8 to flow into the heat preservation tank 9, achieving separation of the ice column and the concentrated wastewater. A third discharge valve 21 is installed on this discharge pipe to control the discharge of the concentrated wastewater. The low-temperature concentrated wastewater in the heat preservation tank 9 does not need to be pre-cooled. It is sent back into the reactor 8 through a fourth discharge valve 22 and a third discharge pump 15 connected to the bottom outlet of the heat preservation tank 9 for a new round of freeze-concentration, forming a closed-loop pipeline. A discharge flow meter 23 is also installed on this closed-loop pipeline. This achieves rapid separation of the concentrated wastewater and ice, and the circulating concentrated wastewater can adjust the volume and concentration of the dye wastewater in the reactor 8, improving the freeze-concentration efficiency.

[0061] Example 4

[0062] The components and structures described in Examples 1 / 2 / 3 remain unchanged; please refer to [link / reference]. Figure 4In this embodiment, a scrubber 14 is also installed at the open end of the shell 12 in the ice-melting device 10. The scrubber 14 is connected to a water storage tank 13. The scrubber 14 is ring-shaped, with multiple nozzles arranged at multiple angles on the inner ring. When the cooling jacket 71 passes through it, the 0°C washing water in the water storage tank 13 washes the ice column through the scrubber 14, cleaning the residual dye wastewater adhering to the surface of the ice column. At this time, if the reactor 8 and the shell 12 are arranged side by side, a three-way valve needs to be installed at the bottom of the shell 12 to separately discharge the washing dye wastewater and ice water. If the reactor 8 and the shell 12 are stacked, the washing dye wastewater falls directly into the reactor 8, and the melted ice water needs to be discharged through valves or other structures.

[0063] To verify the technical effects achieved by the present invention, a simulation experiment was conducted using Example 4 as an example. 400 mL of dye wastewater was taken, and the volume of the reaction vessel 8 in the simulated freeze-concentration device 4 was 100 mL. 400 mL of dye wastewater was pre-taken in a reagent bottle and stored overnight at 4°C in a refrigerator for pre-cooling. Before the experiment began, the freeze-concentration device 4 was allowed to reach its set temperature;

[0064] At different temperatures, dye wastewater was frozen and concentrated with stirring speeds of 0 r / min, 200 r / min, 300 r / min, and 400 r / min, while maintaining a constant freezing time of 60 min. Then, the dye wastewater was frozen at -6℃, -10℃, -14℃, and -18℃, while the circumferential speed of the stirrer was kept constant at 300 r / min for a period of time. Ice crystals formed in the concentrated solution were separated, washed with pure water at 4℃, and then the COD and salt content, as well as the volumes of the concentrated solution and the melted ice water, were measured.

[0065] To simultaneously achieve the highest possible salt removal rate and organic matter concentration efficiency, coolant temperature, freezing time, and stirring rate were considered as independent variables, while salt removal rate and COD concentration efficiency were considered as dependent variables. Based on Box-Behnken experimental design theory, the conditions of the key factors were further optimized, and the interactions between the factors were examined, yielding optimal results. The results are as follows: Figures 6 to 11 As shown, where, Figure 6 The effects of stirring rate on salt removal efficiency (a) and COD concentration efficiency (b) at different coolant temperatures are shown in order (freezing time: 60 min). Figure 7 The effects of coolant temperature on salt removal efficiency (a) and COD concentration efficiency (b) at different ice formation rates are shown in order (stirring speed: 300 r / min). Figure 8 , Figure 9 The response surface contour plot shows the effect of the interaction between the two factors on salt removal efficiency. Figure 10 , Figure 11The response surface contour plot shows the effect of the interaction between the two factors on COD concentration efficiency.

[0066] In summary, the method and apparatus for treating dye wastewater by freeze concentration provided by this invention require no additional chemical substances, do not cause secondary pollution, are simple and practical, and are more energy-efficient than evaporation concentration. Compared with existing freezing methods, the continuous concentration of dye wastewater is more efficient and the treatment process is faster. The dynamic ice crystallizer designed in this invention, with a cooling stirring rod as the main component, freezes by increasing heat transfer between the solution and the coolant. Ice grows on the cooling surface, eventually producing large ice crystals with higher purity, making it easier to separate the ice crystals from the mother liquor, thereby improving concentration performance. In addition, the advantage of this invention lies in its simple structure and operation, which reduces treatment costs. This is because fewer moving parts are required, and large ice crystals are produced, making ice-solution separation easier.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An apparatus for cryogenic concentration treatment of dye wastewater, comprising: Waste liquid tank (1); The cryogenic concentration device (4) includes a reaction vessel (8), a cooling and stirring mechanism and a constant temperature device (5). The reaction vessel (8) is connected to the waste liquid tank (1). The cooling and stirring mechanism is detachably installed inside the reaction vessel (8). The constant temperature device (5) is connected to the cooling and stirring mechanism to enable the cooling and stirring device to form a low temperature. The ice melting device (10) includes a housing (12), a conveying mechanism (11) and an ice crushing mechanism (16), wherein the ice crushing mechanism (16) is disposed inside the housing (12), and the conveying mechanism (11) is used to move the cooling stirring mechanism into the housing (12); The cooling and stirring mechanism is characterized in that it comprises: A cooling stirring rod (7) is disposed inside the reactor (8). The cooling stirring rod (7) includes a cooling sleeve (71) and a stirring rod. The stirring rod is rotatably sleeved inside the cooling sleeve (71). The bottom of the stirring rod extends outside the cooling sleeve (71) and is fixedly connected with multiple stirring paddles (72). A CNC motor (6) is detachably connected to the outside of the reactor (8), and its rotating shaft is fixedly connected to the stirring rod to drive the stirring rod to rotate. The top of the reactor (8) is provided with an opening (82) for the cooling stirring rod (7) to enter and exit the reactor (8); the conveying mechanism (11) is used to lift the entire cooling stirring mechanism from the opening (82) and send it into the shell (12); if the shell (12) and the reactor (8) are arranged side by side, the conveying mechanism (11) will move laterally a certain distance and send the cooling stirring mechanism into the reactor (8); if the shell (12) and the reactor (8) are stacked on top of each other, the cooling stirring mechanism will be directly lifted into the shell (12).

2. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 1, characterized in that, It also includes a precooling device (2), which is located between the waste liquid tank (1) and the reaction vessel (8) for precooling the dye wastewater entering the reaction vessel (8).

3. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 1, characterized in that, The temperature control device (5) has a circulating coolant inside, and the temperature control device (5) is connected to the cooling jacket.

4. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 3, characterized in that, The outer wall of the reactor (8) is provided with a jacket, and the constant temperature device (5) is connected to the jacket.

5. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 1, characterized in that, The reactor (8) is connected to a heat preservation tank (9), and the heat preservation tank (9) is also equipped with a drain pipe for reconnecting with the reactor (8) to form a closed-loop pipeline.

6. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 5, characterized in that, A discharge flow meter (23) is installed on the drain pipe of the heat preservation tank (9).

7. The apparatus for cryogenic concentration treatment of dye wastewater according to claim 1, characterized in that, The ice-melting device (10) also includes a water storage tank (13) and a scrubber (14). The water storage tank (13) is connected to the scrubber (14), and the scrubber (14) is fixedly connected to the upper opening of the housing (12).

8. A method for freeze-concentrating dye wastewater, characterized in that, The apparatus for treating dye wastewater by cryogenic concentration as described in any one of claims 1 to 7 includes the following steps: Step S1: Send the dye wastewater in the waste liquid tank (1) into the precooling device (2). The dye wastewater undergoes heat exchange in the precooling device (2) to achieve preliminary cooling. The unfrozen dye wastewater sent into the precooling device (2) is sent into the reaction vessel (8) through the discharge pipe. Step S2: After the dye wastewater is fed into the reactor (8), the constant temperature device (5) maintains the cold field of the reactor (8); the ice generated by freezing grows on the cooling stirring rod (7) in the reactor (8) to form ice columns, thereby achieving the initial concentration of dye wastewater and separation of ice crystals; Step S3: Turn on the ice melting device (10), move the ice column on the cooling stirring rod (7) into the ice melting device (10), wash and break the ice in sequence, and the broken ice falls to the bottom of the ice melting device (10) to melt and be collected for use. Steps S1 and S3 are repeated in a cycle, and the remaining concentrate is discharged from the reactor (8).

9. The method for freeze-concentrating dye wastewater according to claim 8, characterized in that, In step S2, the remaining unfrozen concentrate flows from the reactor (8) into the insulation tank (9) by gravity. The concentrate in the insulation tank (9) is then pumped back into the reactor (8) for mixing and then frozen again. This process is repeated in a cycle.

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