A solid-liquid separation device and method for water-based paint cleaning solvent

Abstract

The present invention relates to the technical field of solid-liquid separation processing, and in particular to a solid-liquid separation device and method for water-based paint cleaning solvent. The separation device includes: a flocculation unit, a flocculation separation unit, a flocculation detection unit, a separation detection unit, a material residue separation unit, a clear liquid recovery unit, a flocculation control unit, and a separation control unit. The present invention flocculates the filtered concentrated solution of the water-based paint cleaning solvent again, and pumps the upper flocculated mixed solution after flocculation into a centrifugal separator to separate it into material residue and clarified liquid. The concentrated solution passes through the flocculation and solid-liquid separation device, and the membrane system concentrated solution can be effectively separated into solid and liquid. The weight of the solid residue only accounts for about 10% of the original waste liquid weight. After drying and evaporation, 5% of the water content can be reduced, achieving a weight reduction of more than 95% of hazardous waste, which can improve the effective utilization rate of the water-based paint cleaning solvent and reduce the amount of waste to be processed.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-liquid separation processing, and in particular to a solid-liquid separation device and method for water-based paint cleaning solvent. Background Art

[0002] Paint shops typically use dry spray booths to achieve 100% automated painting of both interior and exterior vehicle panels. For example, B1 and B2 exterior panel painting utilizes internal power supply, with isolation lines and spray heads cleaned after each spray cycle. Interior panel painting utilizes gear pumps without power supply, with spray heads cleaned after every two cycles. This generates significant amounts of aqueous solvent waste daily, requiring hazardous waste disposal and significant waste disposal costs.

[0003] Wastewater treatment plants are unable to process high COD levels, and outsourcing hazardous waste treatment costs are substantial. Separating the wastewater and recycling the solvents would reduce emissions, lower outsourcing costs, reuse valuable ethylene glycol butyl ether, and reduce pure water consumption. In the hazardous waste treatment process, static sedimentation and filtration are the primary processes. Static sedimentation can settle large amounts of turbid liquid and metal particles, allowing the cleaner upper layer to be filtered and ultrafiltered, significantly improving filtration efficiency. However, the concentrated liquid after filtration often contains approximately 20% of the original liquid, still containing a significant amount of liquid. Consequently, further recovery of the liquid in the concentrated liquid after filtration has become a challenge. Summary of the Invention

[0004] To this end, the present invention provides a solid-liquid separation device and method for aqueous coating cleaning solvents, which is used to overcome the problem in the prior art that the concentrated liquid after filtration using a filtration process has a high liquid content, resulting in low separation efficiency of solid-liquid separation.

[0005] To achieve the above objectives, the present invention provides, on the one hand, a solid-liquid separation device for a water-based paint cleaning solvent, comprising:

[0006] A flocculation unit connected to the concentrate output pipe of the filtering device includes a flocculation tank for carrying the filtered solvent concentrate, a stirring mechanism for stirring the liquid in the tank, and a flocculant filling mechanism for filling the flocculant into the flocculation tank;

[0007] a flocculation and separation unit connected to the flocculation tank and comprising a bubble generating mechanism arranged at the lower part of the flocculation tank;

[0008] a flocculation detection unit, which is used to obtain the liquid level height in the flocculation tank, the concentration of the concentrated liquid in the flocculation tank, and the clarity of the clear liquid in the flocculation tank;

[0009] A separation detection unit, which is used to obtain the bubble generation speed, bubble diameter and the height of the clear liquid in the flocculation tank;

[0010] a material-slag separation unit connected to the flocculation output end at the upper portion of the flocculation tank, for separating the flocculation mixture in the flocculation tank into material slag and clarified liquid by centrifugal separation;

[0011] a clear liquid recovery unit connected to the material-slag separation unit and the clear liquid output end at the bottom of the flocculation tank, for recovering the clarified liquid after centrifugal separation and the clarified liquid output from the flocculation tank;

[0012] a flocculation control unit, connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, and the separation detection unit, respectively, for determining an initial filling amount of a flocculant based on the concentrated solution concentration and the liquid level in the flocculation tank, determining an adjustment amount of the flocculant filling based on the clarity of the clear liquid, and determining whether flocculation is completed based on the clarity of the clear liquid in the flocculation tank;

[0013] a separation control unit, which is respectively connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, the separation detection unit and the flocculation control unit, and is used to determine the stirring speed of the stirring mechanism and determine the opening of the bubble generating mechanism based on the flocculation completion result, adjust the stirring height of the stirring mechanism according to the height of the clarified liquid after the bubble generating mechanism is turned on for a set time, and determine whether to adjust the bubble generation speed and bubble diameter based on the clear liquid height and the total liquid level height in the flocculation tank.

[0014] Furthermore, the stirring mechanism includes:

[0015] A stirring blade is provided in the flocculation tank and is not connected to the inner walls of the flocculation tank, wherein the stirring rotation axis of the stirring blade is perpendicular to the horizontal plane;

[0016] A height adjustment component is connected to the upper cover of the flocculation tank and the stirring blade, and is used for adjusting the height of the stirring blade.

[0017] Furthermore, the bubble generating mechanism includes:

[0018] a gas storage chamber carrying gas for forming bubbles to be input into the flocculation tank;

[0019] The bubble generator is connected to the gas storage chamber and is used for forming bubbles with a set diameter, controlling the bubble generation speed and delivering the bubbles with the set diameter and the set bubble generation speed to the flocculation tank.

[0020] Furthermore, the flocculation control unit calculates the flocculation quality based on the concentrated solution concentration and the liquid level in the flocculation tank to determine the initial filling amount of the flocculant.

[0021] Furthermore, the flocculation control unit determines the addition adjustment amount of the flocculant based on the comparison result of the clarity of the clear liquid and the preset clarity threshold, wherein,

[0022] The flocculation control unit determines to increase the amount of flocculant added based on a comparison result that the clarity of the clear liquid is less than a preset clarity threshold, and the addition adjustment amount is positively correlated with the clarity difference.

[0023] Furthermore, the flocculation control unit determines whether flocculation is completed by determining whether the clarity of the clear liquid in the flocculation tank reaches the preset clarity threshold. If the clarity of the clear liquid is greater than or equal to the preset clarity threshold, the flocculation control unit determines that flocculation is completed.

[0024] Furthermore, the separation control unit determines to reduce the stirring speed of the stirring mechanism based on the judgment result that the flocculation is completed.

[0025] Furthermore, the separation control unit adjusts the stirring height of the stirring mechanism according to the height of the clarified liquid collected at a preset time after the stirring speed is reduced, wherein the height of the clarified liquid is positively correlated with the stirring height of the stirring mechanism, and the stirring height of the stirring mechanism is lower than the height of the clarified liquid.

[0026] Furthermore, the separation control unit determines whether to adjust the bubble generation speed and bubble diameter based on the ratio of the clarified liquid height to the total liquid level in the flocculation tank, including:

[0027] If the ratio is lower than a preset ratio, the separation control module determines to increase the bubble generation speed;

[0028] If the rate of change of the ratio is lower than a preset rate, the separation control module determines to increase the bubble diameter, and the bubble diameter is lower than a bubble diameter threshold, which is determined according to an average size of flocs.

[0029] On the other hand, the present invention provides a solid-liquid separation method for an aqueous coating cleaning solvent, which uses the above-mentioned solid-liquid separation device for an aqueous coating cleaning solvent to perform solid-liquid separation, and the solid-liquid separation method comprises:

[0030] Step S1, introducing the concentrated liquid separated by the filtering device into a flocculation tank;

[0031] Step S2, determining an initial filling amount of flocculant based on the concentration of the concentrated solution and the liquid level in the flocculation tank, and starting a stirring mechanism to stir so that the flocculant and the concentrated solution are mixed to form flocs;

[0032] Step S3, obtaining the clarity of the clear liquid in the flocculation tank, determining the addition adjustment amount of the flocculant based on the clarity of the clear liquid, and determining whether the flocculation is completed according to the clarity of the clear liquid in the flocculation tank;

[0033] Step S4, obtaining a determination result of whether flocculation is completed, adjusting the stirring speed of the stirring mechanism based on the determination result of whether flocculation is completed, and turning on the bubble generating mechanism;

[0034] Step S5, stirring the flocculation mixed liquid at the adjusted stirring speed for a set time, and obtaining the height of the clarified liquid in the flocculation tank;

[0035] Step S6, adjusting the stirring height of the stirring mechanism according to the height of the clarified liquid to continuously stir the flocculation mixed liquid;

[0036] Step S7, obtaining the height of the clear liquid in the flocculation tank, and determining whether to adjust the bubble generation speed and bubble diameter based on the clear liquid height and the total liquid level;

[0037] Step S8, obtaining a determination result of separation completion, and based on the determination result of separation completion, pumping the upper layer of flocculent in the flocculent tank to a centrifuge for material-slag separation, and transporting the lower layer of clear liquid to a clear liquid recovery end;

[0038] The gas used by the bubble generating mechanism in step S4 to generate bubbles is selected according to the activity of the flocculation, including:

[0039] If the flocculent floccules need to be oxidized in the subsequent resource recovery process, the gas used is determined to be an oxygen-containing gas;

[0040] If the flocculent needs to be oxygen-free in the subsequent resource recovery process, the gas used is determined to be an inert gas.

[0041] Compared with the prior art, the beneficial effect of the present invention lies in that the present invention re-flocculates the filtered concentrated solution of the aqueous paint cleaning solvent, and pumps the upper layer of the flocculated mixed liquid into a centrifugal separator to separate it into slag and clarified liquid. The concentrated liquid passes through the flocculation and solid-liquid separation device, which can effectively separate the solid and liquid of the membrane system concentrate. The weight of the solid slag only accounts for about 10% of the original waste liquid weight, and it can also reduce 5% of the water content after drying and evaporation, achieving a weight reduction of more than 95% of hazardous waste, which can improve the solid-liquid separation rate of the aqueous paint cleaning solvent, improve the effective utilization rate of the aqueous paint cleaning solvent and reduce the amount of waste processed.

[0042] Furthermore, the present invention provides a bubble generating mechanism in the flocculation tank and determines whether the bubble generating mechanism is turned on according to the flocculation completion result, thereby achieving upper and lower layer separation of flocculation and clear liquid in the flocculation tank, thereby reducing the amount of mixed liquid pumped to the centrifugal separator and improving the flocculation treatment efficiency.

[0043] Furthermore, the present invention determines the stirring speed of the stirring mechanism based on the coagulation completion result, and adjusts the stirring height of the stirring mechanism according to the height of the clarified liquid after the bubble generating mechanism is turned on for a set time. The bubbles can be attached to the coagulation to make the coagulation in the coagulation mixture float, thereby increasing the floating speed of the coagulation body in the coagulation tank and the separation speed of the coagulation body and the clarified liquid.

[0044] Furthermore, the present invention determines whether to adjust the bubble generation speed and bubble diameter by the clear liquid height and the total liquid level in the flocculation tank, and can specifically adjust the bubble size and bubble amount according to the floating situation of the flocculation, thereby further effectively improving the separation speed of the flocculation body and the clarified liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a connection block diagram of a solid-liquid separation device for water-based paint cleaning solvent according to an embodiment of the present invention;

[0046] Figure 2 Schematic diagram of a solid-liquid separation device for water-based paint cleaning solvent according to an embodiment of the present invention;

[0047] Figure 3 This is a flow chart of a solid-liquid separation method for a water-based paint cleaning solvent according to an embodiment of the present invention;

[0048] In the figure: 1, flocculation tank; 2, stirring mechanism; 3, flocculant filling mechanism; 4, bubble generating mechanism; 5, material-slag separation unit; 6, clear liquid recovery unit. DETAILED DESCRIPTION

[0049] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0050] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0051] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0052] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0053] See also Figure 1 and Figure 2 As shown, Figure 1 Schematic diagram of a solid-liquid separation device for water-based paint cleaning solvent according to an embodiment of the present invention. Figure 2 Schematic diagram of a solid-liquid separation device for water-based paint cleaning solvent according to an embodiment of the present invention.

[0054] This embodiment provides a solid-liquid separation device for aqueous coating cleaning solvent, comprising:

[0055] The flocculation unit is connected to the concentrate output pipe of the filtering device and includes a flocculation tank 1 for carrying the filtered solvent concentrate, a stirring mechanism 2 for stirring the liquid in the tank, and a flocculant filling mechanism 3 for filling the flocculant into the flocculation tank;

[0056] A flocculation and separation unit, connected to the flocculation tank, includes a bubble generating mechanism 4 provided at the lower portion of the flocculation tank;

[0057] a flocculation detection unit, which is used to obtain the liquid level height in the flocculation tank, the concentration of the concentrated liquid in the flocculation tank, and the clarity of the clear liquid in the flocculation tank;

[0058] A separation detection unit, which is used to obtain the bubble generation speed, bubble diameter and the height of the clear liquid in the flocculation tank;

[0059] a material-slag separation unit 5 connected to the flocculation output end at the upper portion of the flocculation tank, for separating the flocculation mixture in the flocculation tank into material slag and clarified liquid by centrifugal separation;

[0060] a clear liquid recovery unit 6, which is connected to the material-slag separation unit and the clear liquid output end at the bottom of the flocculation tank, and is used to recover the clarified liquid after centrifugal separation and the clarified liquid output from the flocculation tank;

[0061] a flocculation control unit, connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, and the separation detection unit, respectively, for determining an initial filling amount of a flocculant based on the concentrated solution concentration and the liquid level in the flocculation tank, determining an adjustment amount of the flocculant filling based on the clarity of the clear liquid, and determining whether flocculation is completed based on the clarity of the clear liquid in the flocculation tank;

[0062] a separation control unit, which is respectively connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, the separation detection unit and the flocculation control unit, and is used to determine the stirring speed of the stirring mechanism and determine the opening of the bubble generating mechanism based on the flocculation completion result, adjust the stirring height of the stirring mechanism according to the height of the clarified liquid after the bubble generating mechanism is turned on for a set time, and determine whether to adjust the bubble generation speed and bubble diameter based on the clear liquid height and the total liquid level height in the flocculation tank.

[0063] Specifically, the stirring mechanism includes:

[0064] A stirring blade is provided in the flocculation tank and is not connected to the inner walls of the flocculation tank, wherein the stirring rotation axis of the stirring blade is perpendicular to the horizontal plane;

[0065] A height adjustment component is connected to the upper cover of the flocculation tank and the stirring blade, and is used for adjusting the height of the stirring blade.

[0066] In practice, the height adjustment component controls the length of the stirring shaft of the stirring blade through the lifting structure to adjust the height of the stirring blade.

[0067] The flocculant filling mechanism can be implemented by any method in the prior art, as long as it can fill a set mass of flocculant into the flocculant tank.

[0068] Specifically, the bubble generating mechanism includes:

[0069] a gas storage chamber carrying gas for forming bubbles to be input into the flocculation tank;

[0070] The bubble generator is connected to the gas storage chamber and is used for forming bubbles with a set diameter, controlling the bubble generation speed and delivering the bubbles with the set diameter and the set bubble generation speed to the flocculation tank.

[0071] In practice, the bubble generator has a bubble outlet located on the bottom inner wall of the flocculation tank to deliver bubbles to the solution within the flocculation tank. It is understood that there is no limit to the number of bubble outlets, and typically, the bubble outlets are evenly distributed on the bottom inner wall of the flocculation tank. A bubble generator is typically used.

[0072] Specifically, the flocculation control unit calculates the flocculation quality based on the concentrate concentration and the liquid level in the flocculation tank to determine the initial filling amount of the flocculant.

[0073] In a specific embodiment, the concentrate mass can be obtained based on the concentrate concentration and the liquid level in the flocculation tank, and the initial flocculant filling amount is determined according to the concentrate mass. Generally, this is implemented by setting up a comparison table between the concentrate mass and the initial flocculant filling amount.

[0074] In another specific embodiment, a comparison table of liquid level heights corresponding to different solution concentration intervals and initial flocculant filling amounts is provided.

[0075] It is understandable that the above-mentioned comparison table between liquid level height and initial flocculant filling amount, and the comparison table between concentrate quality and initial flocculant filling amount can be set according to historical experience or calculated according to concentrate composition, which will not be repeated here.

[0076] Specifically, the flocculation control unit determines the addition adjustment amount of the flocculant based on the comparison result of the clarity of the clear liquid and the preset clarity threshold, wherein:

[0077] The flocculation control unit determines to increase the amount of flocculant added based on a comparison result that the clarity of the clear liquid is less than a preset clarity threshold, and the addition adjustment amount is positively correlated with the clarity difference.

[0078] The clarity difference is the difference between the preset clarity threshold and the clarity of the clear liquid. The clearer the solution, the greater the clarity of the clear liquid.

[0079] In practice, the clarity of the clear liquid can be determined based on the turbidity of the solution detected by a photoelectric sensor. The higher the turbidity, the lower the clarity of the clear liquid. The preset clarity threshold is typically set to the clarity of the solvent clear liquid after filtration by the filtration device. Preferably, the initial adjustment amount of the flocculant is set within a range of 10% to 50% of the initial dosage to ensure sufficient flocculation. The greater the clarity difference, the larger the initial adjustment amount within the range.

[0080] Specifically, the flocculation control unit determines whether flocculation is completed by whether the clarity of the clear liquid in the flocculation tank reaches the preset clarity threshold, wherein, if the clarity of the clear liquid is greater than or equal to the preset clarity threshold, the flocculation control unit determines that flocculation is completed; if the clarity of the clear liquid is lower than the preset clarity threshold, the flocculation control unit determines that flocculation is not completed, and increases the injection of flocculant using the above-mentioned injection adjustment amount.

[0081] Specifically, the separation control unit determines to reduce the stirring speed of the stirring mechanism based on the determination result that the flocculation is completed.

[0082] In practice, after the flocculant is added, the stirring mechanism rotates at a high speed (200-500 rpm) to promote the mixing of the flocculant and the solvent concentrate to produce flocs. When the flocculant control unit determines that flocculent floccules are complete, this determination is transmitted to the separation control unit. Based on this determination, the separation control unit determines to reduce the stirring mechanism's stirring speed to a low speed (30-80 rpm) to stabilize the floccules and avoid disrupting bubbles attached to the bottom of the floccules. It is understood that a lower speed can also drive the floccules with bubbles to float upward by disrupting their stability, thereby increasing their floating speed.

[0083] Specifically, the separation control unit adjusts the stirring height of the stirring mechanism according to the height of the clarified liquid collected at a preset time after the stirring speed is reduced, wherein the height of the clarified liquid is positively correlated with the stirring height of the stirring mechanism, and the stirring height of the stirring mechanism is lower than the height of the clarified liquid.

[0084] In practice, the clarified liquid level is typically detected by installing photoelectric sensors at varying heights on the inner wall of the flocculation tank. Each photoelectric sensor is configured with a clear liquid reference value. If the clarity of the clear liquid detected by the photoelectric sensor at a certain height A is greater than or equal to the clear liquid reference value, and the clarity of the clear liquid detected by the photoelectric sensors at all heights below height A is also greater than or equal to the clear liquid reference value, the clarified liquid level is determined to be height A. The clear liquid reference value is generally set to 70% to 85% of the clarity of the solvent clear liquid after filtration by the filtration device to prevent interference from bubbles. Furthermore, during photoelectric sensor detection, bubbles are kept away for a period of time to further prevent bubbles from affecting the clarity of the clear liquid. Preferably, this bubble-free period is set to 10 to 30 seconds.

[0085] It can be understood that the stirring height increases with the height of the clarified liquid, which can improve the stirring efficiency for the flocculants, avoid ineffective stirring of the clear liquid, and improve the floating efficiency of the flocculants.

[0086] Specifically, the separation control unit determines whether to adjust the bubble generation speed and bubble diameter based on the ratio of the clarified liquid height to the total liquid level in the flocculation tank, including:

[0087] If the ratio is lower than a preset ratio, the separation control module determines to increase the bubble generation speed;

[0088] If the rate of change of the ratio is lower than a preset rate, the separation control module determines to increase the bubble diameter, and the bubble diameter is lower than a bubble diameter threshold, which is determined according to an average size of flocs.

[0089] In practice, it is preferred that the bubble size generated by the bubble generating mechanism be set to between 0.1 and 1 mm, the initial bubble generation speed be at least able to meet the requirement that a single bubble output port generates 100 to 500 bubbles per second, and a sufficient number of bubble output ports be provided so that the area of ​​the bubbles generated by each bubble output port covers the entire inner cavity cross-section of the flocculation tank.

[0090] It is understood that the preset ratio is set between 0.3 and 0.5, which can better characterize the height state of the flocculent flocs and adjust the speed of separation of the flocculent flocs from the clear liquid. The preset rate is set to 0.5 to 3 cm / min. Preferably, the preset ratio is set to 0.3 and the preset rate is set to 0.5 cm / min. The bubble diameter threshold can be calculated based on the average size of the historical flocculent flocs. Generally, it is set to 0.1 times the maximum size of the flocculent flocs, or the bubble diameter threshold is determined by experiments based on historical flocculent flotation. Under normal circumstances, the bubble diameter threshold is 1 to 3 mm.

[0091] In a specific embodiment, the ratio is lower than a preset ratio, and the separation control module determines to increase the bubble generation speed. Generally, in a single adjustment, the increased bubble generation speed is 1.5 to 2 times the original bubble generation speed.

[0092] In another specific embodiment, the rate of change of the ratio is lower than a preset rate, and the separation control module determines to increase the bubble diameter. Generally, in a single adjustment, the increased bubble diameter is 1.5 to 2 times the original bubble diameter.

[0093] Specifically, the height of the bubble output port of the bubble generating mechanism can be adjusted accordingly according to the height of the clarified liquid. When the height of the clarified liquid is higher than the minimum height corresponding to when the bubble output port generates bubbles covering the entire cross-section of the inner cavity of the flocculation tank, the height of the bubble output port increases with the height of the clarified liquid, so that the minimum height corresponding to when the bubble output port generates bubbles covering the entire cross-section of the inner cavity of the flocculation tank is the height of the clarified liquid detected in the current cycle.

[0094] This embodiment also provides a solid-liquid separation method A for aqueous coating cleaning solvents, which uses the above-mentioned solid-liquid separation device for aqueous coating cleaning solvents to perform solid-liquid separation. The solid-liquid separation method includes:

[0095] Step S1a, introducing the concentrated solution separated by the filtration device into a flocculation tank;

[0096] Step S2a, determining an initial filling amount of flocculant based on the concentration of the concentrated solution and the liquid level in the flocculation tank, and starting a stirring mechanism to stir the solution so that the flocculant and the concentrated solution are mixed to form flocs;

[0097] Step S3a, obtaining the clarity of the clear liquid in the flocculation tank, determining the addition adjustment amount of the flocculant based on the clarity of the clear liquid, and determining whether the flocculation is completed according to the clarity of the clear liquid in the flocculation tank;

[0098] Step S4a, obtaining a determination result of whether flocculation is completed, adjusting the stirring speed of the stirring mechanism based on the flocculation completion result, and turning on the bubble generating mechanism;

[0099] Step S5a, stirring the flocculation mixed liquid at the adjusted stirring speed for a set time, and obtaining the height of the clarified liquid in the flocculation tank;

[0100] Step S6a, adjusting the stirring height of the stirring mechanism according to the height of the clarified liquid to continuously stir the flocculation mixed liquid;

[0101] Step S7a, obtaining the height of the clear liquid in the flocculation tank, and determining whether to adjust the bubble generation speed and bubble diameter based on the clear liquid height and the total liquid level;

[0102] Step S8a, obtaining a determination result of separation completion, and based on the determination result of separation completion, pumping the upper layer of flocculent in the flocculent tank to a centrifuge for material-slag separation, and transporting the lower layer of clear liquid to a clear liquid recovery terminal;

[0103] The gas used by the bubble generating mechanism in step S4a to generate bubbles is selected according to the activity of the flocculation, including:

[0104] If the flocculent floccules need to be oxidized in the subsequent resource recovery process, the gas used is determined to be an oxygen-containing gas;

[0105] If the flocculation needs to be oxygen-free in the subsequent resource recovery process, the gas used is determined to be an inert gas. Preferably, carbon dioxide gas is used in the implementation.

[0106] Specifically, in step S8a, if the clear liquid height reaches the set height or the ratio of the clear liquid height to the total liquid level changes within 5% of the clear liquid height within 3 to 5 minutes, or the clear liquid height decreases, the separation is determined to be complete, and the determination result of the separation completion is transmitted to the corresponding mechanism to pump the upper layer of flocculants in the flocculant tank to the centrifuge for material-slag separation, and transport the lower layer of clear liquid to the clear liquid recovery end.

[0107] The upper flocculent layer is further separated by a centrifuge to form slag and clear liquid, which are recovered separately.

[0108] This embodiment also provides a solid-liquid separation method B for aqueous coating cleaning solvents, which uses the above-mentioned solid-liquid separation device for aqueous coating cleaning solvents to perform solid-liquid separation. The difference between the solid-liquid separation method and the method A is that the bubble generating mechanism is not used. The solid-liquid separation method includes:

[0109] Step S1b, introducing the concentrated solution separated by the filtration device into a flocculation tank;

[0110] Step S2b, determining an initial filling amount of flocculant based on the concentration of the concentrated solution and the liquid level in the flocculation tank, and starting a stirring mechanism to stir so that the flocculant and the concentrated solution are mixed to form flocs;

[0111] Step S3b, obtaining the clarity of the clear liquid in the flocculation tank, determining the addition adjustment amount of the flocculant based on the clarity of the clear liquid, and determining whether the flocculation is completed according to the clarity of the clear liquid in the flocculation tank;

[0112] Step S4b, obtaining a determination result of flocculation completion, stopping the stirring mechanism and keeping the bubble generating mechanism inactive based on the flocculation completion result, and allowing the flocculent residue to settle;

[0113] Step S5b, obtaining the height of the clarified liquid in the flocculation tank, and determining that the flocculent residue has been completely settled and the floc-liquid separation is complete when the clarified liquid height drops to a preset height value, wherein the preset height is determined based on the average percentage of the sedimentation layer to the total liquid level of the flocculation tank in historical data;

[0114] Step S6b, obtaining a determination result of separation completion, and based on the determination result of separation completion, pumping the lower layer of flocculent in the flocculent tank to a centrifuge for material-slag separation, and conveying the upper layer of clear liquid to a clear liquid recovery end for filtration and collection;

[0115] The difference from method A is that in step S6b, the clear liquid recovery end of the flocculation tank is located at the upper part of the flocculation tank and is higher than or equal to a preset height, and the flocculent residue recovery end of the flocculation tank is located at the bottom of the flocculation tank.

[0116] Specifically, in step S5b, if the clear liquid height reaches a preset height or the ratio of the clear liquid height to the total liquid level changes within 5% of the clear liquid height within 3 to 5 minutes, or the clear liquid height rises, the separation is determined to be complete, and the determination result of the separation completion is transmitted to the corresponding mechanism to pump the lower layer of flocculants in the flocculant tank to the centrifuge for material-slag separation, and transport the upper layer of clear liquid to the clear liquid recovery end.

[0117] The upper flocculent layer is further separated by a centrifuge to form slag and clear liquid, which are recovered separately.

[0118] In practice, compared with method B, method A can: 1. avoid the presence of flocs in the supernatant due to insufficient sedimentation of flocculated precipitates or flocs that are too small; 2. overcome the need for sedimentation to settle to the bottom for a long time; 3. overcome the problem of mixed residues in the supernatant due to insufficient extraction of flocs at the bottom during the centrifuge process and the re-oscillation and floating of flocs.

[0119] The solid-liquid separation device of the present invention flocculates concentrated liquid by using a flocculant. Since the flocculent structure is loose, bubbles are attached to the bottom of the flocculent, causing the flocculent to float to the upper layer of the tank body, so that the flocculent is in the upper layer and the clear liquid is in the lower layer. During centrifugal extraction, the flocculent is extracted from the upper layer, and the flocculent that is not extracted sufficiently can float again by controlling the size of the bubbles, thereby reducing mixed residues. Since the bubbles are actively added, the flocculent in the upper layer can be extracted in time, and the separation time is shorter than the sedimentation time.

[0120] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A solid-liquid separation device for water-based paint cleaning solvent, characterized in that: include: A flocculation unit connected to the concentrate output pipe of the filtering device includes a flocculation tank for carrying the filtered solvent concentrate, a stirring mechanism for stirring the liquid in the tank, and a flocculant filling mechanism for filling the flocculant into the flocculation tank; The flocculation separation unit is connected to the flocculation tank and includes a bubble generating mechanism arranged at the lower part of the flocculation tank, wherein the bubble generating mechanism includes: a gas storage chamber carrying gas for forming bubbles to be input into the flocculation tank; a bubble generator connected to the gas storage chamber, for forming bubbles of a set diameter, controlling the bubble generation speed, and delivering the bubbles of the set diameter and the set bubble generation speed to the flocculation tank; a flocculation detection unit, which is used to obtain the liquid level height in the flocculation tank, the concentration of the concentrated liquid in the flocculation tank, and the clarity of the clear liquid in the flocculation tank; A separation detection unit, which is used to obtain the bubble generation speed, bubble diameter and the height of the clear liquid in the flocculation tank; a material-slag separation unit connected to the flocculation output end at the upper portion of the flocculation tank, for separating the flocculation mixture in the flocculation tank into material slag and clarified liquid by centrifugal separation; a clear liquid recovery unit connected to the material-slag separation unit and the clear liquid output end at the bottom of the flocculation tank, for recovering the clarified liquid after centrifugal separation and the clarified liquid output from the flocculation tank; a flocculation control unit, connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, and the separation detection unit, respectively, for determining an initial filling amount of a flocculant based on the concentration of the concentrated solution and the liquid level in the flocculation tank, determining an adjustment amount of the filling amount of the flocculant based on a comparison result of the clarity of the clear liquid with a preset clarity threshold, and determining whether flocculation is completed based on the clarity of the clear liquid in the flocculation tank, wherein the preset clarity threshold is the clarity of the solvent clear liquid after filtration by the filtration device; a separation control unit, connected to the flocculation unit, the flocculation separation unit, the flocculation detection unit, the separation detection unit, and the flocculation control unit, respectively, for determining, based on a flocculation completion result, to reduce the stirring speed of the stirring mechanism and to determine to activate the bubble generating mechanism, and adjusting the stirring height of the stirring mechanism according to the height of the clarified liquid after the bubble generating mechanism is activated for a set time, the clarified liquid height being a liquid level height at which the clarity of the clear liquid detected by the photoelectric sensor at the corresponding height meets or exceeds a clear liquid reference value, and the clarity of the clear liquid detected by the photoelectric sensors at each height below the corresponding height also meets or exceeds the clear liquid reference value, the clear liquid reference value being 70% to 85% of the clarity of the solvent clear liquid after filtration by the filtration device; And whether to adjust the bubble generation speed and bubble diameter is determined based on the ratio of the clarified liquid height to the total liquid level in the flocculation tank, wherein, If the ratio is lower than a preset ratio, the separation control unit determines to increase the bubble generation speed; If the rate of change of the ratio is lower than a preset rate, the separation control unit determines to increase the bubble diameter, and the bubble diameter is lower than a bubble diameter threshold, and the bubble diameter threshold is determined according to the average size of the flocs; The height of the bubble output port of the bubble generating mechanism is adjusted accordingly according to the height of the clarified liquid. When the height of the clarified liquid is higher than the minimum height corresponding to when the bubble output port generates bubbles covering the entire cross-section of the inner cavity of the flocculation tank, the height of the bubble output port increases with the height of the clarified liquid, so that the minimum height corresponding to when the bubble output port generates bubbles covering the entire cross-section of the inner cavity of the flocculation tank is the height of the clarified liquid detected in the current cycle.

2. The solid-liquid separation device for water-based paint cleaning solvent according to claim 1, characterized in that: The stirring mechanism comprises: A stirring blade is provided in the flocculation tank and is not connected to the inner walls of the flocculation tank, wherein the stirring rotation axis of the stirring blade is perpendicular to the horizontal plane; A height adjustment component is connected to the upper cover of the flocculation tank and the stirring blade, and is used for adjusting the height of the stirring blade.

3. The solid-liquid separation device for water-based paint cleaning solvent according to claim 1, characterized in that: The flocculation control unit calculates the flocculation quality based on the concentrate concentration and the liquid level in the flocculation tank to determine the initial filling amount of the flocculant.

4. The solid-liquid separation device for water-based paint cleaning solvent according to claim 1, characterized in that: The flocculation control unit determines the addition adjustment amount of the flocculant based on the comparison result of the clarity of the clear liquid and the preset clarity threshold, wherein, The flocculation control unit determines to increase the amount of flocculant added based on a comparison result that the clarity of the clear liquid is less than a preset clarity threshold, and the addition adjustment amount is positively correlated with the clarity difference.

5. The solid-liquid separation device for water-based paint cleaning solvent according to claim 4, characterized in that: The flocculation control unit determines whether flocculation is completed by determining whether the clarity of the clear liquid in the flocculation tank reaches the preset clarity threshold. If the clarity of the clear liquid is greater than or equal to the preset clarity threshold, the flocculation control unit determines that flocculation is completed.

6. The solid-liquid separation device for aqueous paint cleaning solvent according to claim 5, characterized in that: The separation control unit determines to reduce the stirring speed of the stirring mechanism based on the determination result that the flocculation is completed.

7. The solid-liquid separation device for water-based paint cleaning solvent according to claim 1, characterized in that: The separation control unit adjusts the stirring height of the stirring mechanism according to the height of the clarified liquid collected at a preset time after the stirring speed is reduced, wherein the height of the clarified liquid is positively correlated with the stirring height of the stirring mechanism, and the stirring height of the stirring mechanism is lower than the height of the clarified liquid.

8. A solid-liquid separation method for water-based paint cleaning solvent, characterized in that: The solid-liquid separation device for aqueous coating cleaning solvent according to any one of claims 1 to 7 is used for solid-liquid separation, and the solid-liquid separation method includes: Step S1, introducing the concentrated liquid separated by the filtering device into a flocculation tank; Step S2, determining an initial filling amount of flocculant based on the concentration of the concentrated solution and the liquid level in the flocculation tank, and starting a stirring mechanism to stir so that the flocculant and the concentrated solution are mixed to form flocs; Step S3, obtaining the clarity of the clear liquid in the flocculation tank, determining the addition adjustment amount of the flocculant based on the clarity of the clear liquid, and determining whether the flocculation is completed according to the clarity of the clear liquid in the flocculation tank; Step S4, obtaining a determination result of whether flocculation is completed, adjusting the stirring speed of the stirring mechanism based on the determination result of whether flocculation is completed, and turning on the bubble generating mechanism; Step S5, stirring the flocculation mixed liquid at the adjusted stirring speed for a set time, and obtaining the height of the clarified liquid in the flocculation tank; Step S6, adjusting the stirring height of the stirring mechanism according to the height of the clarified liquid to continuously stir the flocculation mixed liquid; Step S7, obtaining the height of the clear liquid in the flocculation tank, and determining whether to adjust the bubble generation speed and bubble diameter based on the clear liquid height and the total liquid level; Step S8, obtaining a determination result of separation completion, and based on the determination result of separation completion, pumping the upper layer of flocculent in the flocculent tank to a centrifuge for material-slag separation, and transporting the lower layer of clear liquid to a clear liquid recovery end; The gas used by the bubble generating mechanism in step S4 to generate bubbles is selected according to the activity of the flocculation, including: If the flocculent floccules need to be oxidized in the subsequent resource recovery process, the gas used is determined to be an oxygen-containing gas; If the flocculent needs to be oxygen-free in the subsequent resource recovery process, the gas used is determined to be an inert gas.

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