System for recovering and treating PVDF (Polyvinylidene Fluoride) resin in wastewater

Abstract

The utility model discloses a system for recovering and treating PVDF (Polyvinylidene Fluoride) resin in wastewater, and relates to the technical field of fluorine-containing resin wastewater treatment. The recovery treatment system comprises a grit chamber, a middle chamber, a filter press, a dryer, a cyclone separator and a sedimentation device which are connected in sequence; and a pH adjusting device is arranged in the grit chamber. According to the system for recycling and treating the PVDF resin in the waste water, impurities such as silt with the density heavier than that of water in the waste water are removed through sedimentation of the grit chamber, the pH is adjusted through the pH adjusting device, the effects of defoaming and reducing breeding of bacterial colonies are achieved, and the phenomenon that filter cloth in a follow-up filter press is blocked is avoided. After the wastewater is subjected to dehydration treatment through a filter press, an obtained solid-phase material is treated through a dryer, a cyclone separator and a sedimentation device in sequence, and PVDF resin powder is obtained.

Description

Technical Field

[0001] The utility model relates to the technical field of fluorine-containing resin wastewater treatment, and more specifically to a PVDF resin recovery and treatment system in wastewater. Background Art

[0002] PVDF (polyvinylidene fluoride) is a fluorine-containing functional resin material with good chemical stability, electrical insulation performance, and super weather resistance. It is widely used in the fields of petrochemicals, electronics and fluorocarbon coatings. In the PVDF production process, the reaction system is divided into emulsion polymerization and suspension polymerization. Both reaction systems require a polymerization kettle for polymerization reaction, and a certain amount of emulsifier needs to be added to ensure dispersion. After the polymerization reaction, the corresponding semi-finished product flows through the next process for washing. In the above production process, a large amount of production wastewater will be generated. The wastewater comes from the need to use a high-pressure water gun to clean the reactor after each batch of reaction and the washing of the reaction production resin. Generally, the production of 1 ton of PVDF will generate 40-60 tons of wastewater, and a large amount of foam and a small amount of PVDF resin float in this wastewater.

[0003] In industrial production, this wastewater needs to undergo environmental protection treatment. The disposal process will consume high treatment costs and occupy a large water storage area. If the foam in the wastewater can be removed and the PVDF resin can be recovered in advance, the pressure and cost of downstream environmental water treatment will be greatly reduced, and the operating costs of enterprises will be reduced.

[0004] Patent 220078866U proposes a system for recycling water from PVDF production. It proposes that the wastewater contains a lot of foam and water-insoluble PVDF suspended particles, which will enter the water recycling system together with the wastewater, and the cost of recycling PVDF production wastewater is too high. Therefore, after the wastewater is treated with a filter press, the filtrate is subjected to an ultrafiltration system, a nanofiltration system, and a reverse osmosis machine respectively, so that the PVDF washing wastewater can be reused as PVDF washing water after being filtered in the system; however, the PVDF resin is not effectively recovered in this process, resulting in a waste of resources. At the same time, the PVDF wastewater contains a large amount of foam, which is easy to clog in the transportation pipeline, and the cost of directly entering the filter press for treatment is high. Utility Model Content

[0005] The utility model aims to overcome the defects and shortcomings of the existing PVDF production wastewater system in which PVDF resin cannot be recovered, and to provide a PVDF resin recovery and treatment system in wastewater.

[0006] The above-mentioned purpose of the utility model is achieved through the following technical solutions:

[0007] The utility model protects a PVDF resin recovery and treatment system in wastewater, comprising a grit chamber, an intermediate chamber, a filter press, a dryer, a cyclone separator and a sedimentation device which are connected in sequence; a pH regulating device is arranged in the grit chamber.

[0008] The utility model removes impurities heavier than water such as silt in wastewater by sedimentation in a sedimentation tank, and adjusts the pH by a pH adjustment device to achieve defoaming and reduce the growth of bacterial colonies, thereby avoiding the clogging of filter cloth in the subsequent filter press. After the wastewater is dehydrated by the filter press, the solid phase material obtained is sequentially processed by a dryer, a cyclone separator and a sedimentation device to obtain PVDF resin powder.

[0009] Preferably, the pH adjusting device is an alkali solution dripping device, and the dripping speed of the alkali solution dripping device is 1-2 drops / s. The alkali solution is a metal hydroxide solution, including but not limited to an aqueous solution of sodium hydroxide or potassium hydroxide; controlling the dripping speed is conducive to uniform dispersion of the alkali solution and precise regulation of the pH value.

[0010] Preferably, the pH adjusting device is used to adjust the pH value of the grit chamber to 6-8; preferably, the pH is 7; the pH of raw wastewater is generally between 4-6, and the effects of defoaming and reducing the growth of bacterial colonies can be achieved by increasing the pH.

[0011] Preferably, it also includes a magnetic rack, which is located at the outlet of the intermediate pool to absorb magnetic particles in the outlet water. The magnetic rack can absorb raw wastewater, pipeline valves, and magnetic particles generated by pump rotation. The magnetic rack is composed of multiple magnetic rods arranged in an up-and-down staggered manner.

[0012] Preferably, a magnetic frame is provided at the front end of each centrifugal pump after water inlet, which can reduce the damage of large magnetic particles to the pump.

[0013] Preferably, a screw machine is further included, and the screw machine is connected to the discharge end of the filter press to crush the filter cake discharged from the filter press.

[0014] Preferably, it also includes a filtrate reflux system, the water inlet end of the filtrate reflux system is connected to the filter press, and the water outlet end of the filtrate reflux system is connected to the feed end of the grit chamber.

[0015] Preferably, a stirring device is provided at the bottom of the dryer.

[0016] Preferably, it also includes a blast system, the blast system includes a blaster and a heater, the blaster is connected to the heater, and the heater is connected to the bottom of the dryer. The hot air of the blast system blows the powder from the bottom of the heater to the top of the heater and enters the cyclone separator to achieve a drying effect. Preferably, the moisture content of the cyclone separator material is controlled to be ≤2000ppm.

[0017] Preferably, a plurality of parallel baffles are provided inside the sedimentation device, and the baffles are located between the air inlet and the air outlet of the sedimentation device. The baffles can improve the sedimentation efficiency.

[0018] Preferably, the air outlet of the sedimentation device is connected to an induced draft fan.

[0019] Compared with the prior art, the beneficial effects of the utility model are:

[0020] The utility model provides a PVDF resin recovery and treatment system in wastewater, which removes impurities heavier than water such as silt in wastewater by sedimentation in a sand settling tank, and adjusts the pH by a pH adjustment device to achieve defoaming and reduce the growth of bacterial colonies, thereby avoiding the clogging of filter cloth in subsequent filter presses. After the wastewater is dehydrated by the filter press, the solid phase material obtained is sequentially processed by a dryer, a cyclone separator and a sedimentation device to obtain PVDF resin powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a PVDF resin recovery and treatment system in wastewater according to the utility model.

[0022] Figure 2 This is a schematic structural diagram of a PVDF resin recovery and treatment system in wastewater according to Example 3 of the utility model.

[0023] Among them, 1. grit chamber; 21. first intermediate tank; 22. second intermediate tank; 3. filter press; 4. screw machine; 5. feeder; 61. dryer; 62. heater; 63. blower; 7. cyclone separator; 8. sedimentation device; 81. baffle; 9. induced draft fan; 101. first centrifugal pump; 102. second centrifugal pump. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific implementations, but the embodiments do not limit the present invention in any form.

[0025] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent.

[0026] In addition, if there are terms such as "first" and "second", they are only used for descriptive purposes, mainly to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components, and cannot be understood as indicating or implying relative importance.

[0027] Example 1

[0028] A wastewater PVDF resin recovery and treatment system, such as Figure 1 As shown, it includes a sand settling tank 1, an intermediate tank, a filter press 3, a dryer 61, a cyclone separator 7, a sedimentation device 8 and an induced draft fan 9 which are connected in sequence.

[0029] The water outlet of the grit chamber 1 is connected to the intermediate tank via a first centrifugal pump 101. The grit chamber 1 is used for sedimentation and removal of impurities such as silt in the wastewater that are heavier than water.

[0030] Among them, an alkali solution dripping device is provided in the grit chamber 1; when it is in working state, the dripping speed of the alkali solution dripping device is 1-2 drops / s, the alkali solution is sodium hydroxide solution, and the pH value of the wastewater is controlled to 7 to achieve the effect of defoaming and reducing the growth of bacterial colonies.

[0031] The intermediate tank is connected to the filter press 3 via the second centrifugal pump 102. The intermediate tank includes two independent first intermediate tanks 21 and second intermediate tanks 22; in this embodiment, the first centrifugal pump 101 and the second centrifugal pump 102 are formed by connecting two centrifugal pumps of the same specifications in parallel.

[0032] The filter press 3 adopts a plate and frame filter press device, and its filter cloth adopts nylon filter cloth. After the sewage is processed by the filter press 3, filter cake and filtrate are obtained. The filtrate can enter the subsequent purification process for purification until it meets the discharge requirements. The purification process can select membrane filtration treatment. After the sewage is processed by this recovery and treatment system, foam and PVDF resin can be effectively removed, thereby reducing the cost of subsequent purification process treatment; the filter cake is crushed by the screw machine 4 and then transported to the feeder 5. The feeder 5 is provided with a feeding screw, and the material is delivered to the dryer 61 through the feeding screw.

[0033] The dryer 61 is a blast dryer 61, the top of the dryer 61 is connected to the cyclone separator 7; the dryer 61 is connected to the blast system, wherein the blast system includes a blower 63 and a heater 62, the blower 63 is connected to the heater 62, and the heater 62 is connected to the bottom of the dryer 61; the material can be blown to the top discharge port of the dryer 61 through the blast dryer 61. At the same time, a stirring device is also provided at the bottom of the dryer 61 for stirring the material to reduce adhesion.

[0034] After the material is sent to the cyclone separator 7, it is further dispersed and dried. The material with low water content is lighter and is discharged from the top of the cyclone separator 7 into the sedimentation device 8. The material with high water content stays and continues to be dried under the high-temperature gas from the blast dryer 61 until the moisture content of the material is reduced to a certain range and then discharged. In this embodiment, the moisture content of the material discharged from the cyclone separator 7 is controlled to be ≤2000ppm by adjusting the wind speed, temperature and other parameters of the blast system.

[0035] The top of the sedimentation device 8 intercepts the material through a cloth bag and is connected to the induced draft fan 9. A plurality of parallel baffles 81 are provided inside the sedimentation device 8, and the baffles 81 are located between the air inlet of the sedimentation device 8 and the air outlet connected to the induced draft fan 9. After the material enters the sedimentation device 8, it settles and is collected to obtain PVDF resin powder.

[0036] The present embodiment is a system for recovering and treating PVDF resin in wastewater, which removes impurities heavier than water such as silt in the wastewater by sedimentation in a grit chamber 1, and adjusts the pH to achieve defoaming and reduce the growth of bacterial colonies. The wastewater is then processed in turn through a dryer 61, a cyclone separator 7 and a sedimentation device 8 to achieve the recovery of PVDF resin and roughly purify the wastewater, thereby reducing the subsequent purification cost of the PVDF wastewater.

[0037] Example 2

[0038] A wastewater PVDF resin recovery and treatment system, such as Figure 1 As shown, it includes a sand settling tank 1, an intermediate tank, a filter press 3, a dryer 61, a cyclone separator 7, a sedimentation device 8 and an induced draft fan 9 which are connected in sequence.

[0039] The water outlet of the grit chamber 1 is connected to the intermediate tank via a first centrifugal pump 101. The grit chamber 1 is used for sedimentation and removal of impurities such as silt in the wastewater that are heavier than water.

[0040] Among them, an alkali solution dripping device is provided in the grit chamber 1; when it is in working state, the dripping speed of the alkali solution dripping device is 1-2 drops / s, the alkali solution is sodium hydroxide solution, and the pH value of the wastewater is controlled to 7 to achieve the effect of defoaming and reducing the growth of bacterial colonies.

[0041] The intermediate tank is connected to the filter press 3 via the second centrifugal pump 102. The intermediate tank includes two independent first intermediate tanks 21 and second intermediate tanks 22; in this embodiment, the first centrifugal pump 101 and the second centrifugal pump 102 are formed by connecting two centrifugal pumps of the same specifications in parallel.

[0042] Furthermore, a magnetic frame is provided in the pipeline between the first intermediate tank 21, the second intermediate tank 22 and the second centrifugal pump 102. The magnetic frame is composed of a plurality of magnetic rods staggered up and down, and the magnetic particles in the wastewater are adsorbed by the magnetic frame.

[0043] The filter press 3 adopts a plate and frame filter press device, and its filter cloth adopts nylon filter cloth. After the sewage is processed by the filter press 3, filter cake and filtrate are obtained. The filtrate can enter the subsequent purification process for purification until it meets the discharge requirements. The purification process can select membrane filtration treatment. After the sewage is processed by this recovery and treatment system, foam and PVDF resin can be effectively removed, thereby reducing the cost of subsequent purification process treatment; the filter cake is crushed by the screw machine 4 and then transported to the feeder 5. The feeder 5 is provided with a feeding screw, and the material is delivered to the dryer 61 through the feeding screw.

[0044] The dryer 61 is a blast dryer 61, the top of the dryer 61 is connected to the cyclone separator 7; the dryer 61 is connected to the blast system, wherein the blast system includes a blower 63 and a heater 62, the blower 63 is connected to the heater 62, and the heater 62 is connected to the bottom of the dryer 61; the material can be blown to the top discharge port of the dryer 61 through the blast dryer 61. At the same time, a stirring device is also provided at the bottom of the dryer 61 for stirring the material to reduce adhesion.

[0045] After the material is sent to the cyclone separator 7, it is further dispersed and dried. The material with low water content is lighter and is discharged from the top of the cyclone separator 7 into the sedimentation device 8. The material with high water content stays and continues to be dried under the high-temperature gas from the blast dryer 61 until the moisture content of the material is reduced to a certain range and then discharged. In this embodiment, the moisture content of the material discharged from the cyclone separator 7 is controlled to be ≤2000ppm by adjusting the wind speed, temperature and other parameters of the blast system.

[0046] The top of the sedimentation device 8 intercepts the material through a cloth bag and is connected to the induced draft fan 9. A plurality of parallel baffles 81 are provided inside the sedimentation device 8, and the baffles 81 are located between the air inlet of the sedimentation device 8 and the air outlet connected to the induced draft fan 9. After the material enters the sedimentation device 8, it settles and is collected to obtain PVDF resin powder.

[0047] Compared with Example 1, a magnetic frame is provided in the pipeline between the intermediate tank and the second centrifugal pump 102 of this embodiment; the magnetic frame can absorb raw wastewater, pipeline valves and magnetic particles generated by pump rotation, and can reduce the damage of large magnetic particles to the pump.

[0048] Example 3

[0049] A wastewater PVDF resin recovery and treatment system, such as Figure 2As shown, it includes a sand settling tank 1, an intermediate tank, a filter press 3, a dryer 61, a cyclone separator 7, a sedimentation device 8 and an induced draft fan 9 which are connected in sequence.

[0050] The water outlet of the grit chamber 1 is connected to the intermediate tank via a first centrifugal pump 101. The grit chamber 1 is used for sedimentation and removal of impurities such as silt in the wastewater that are heavier than water.

[0051] Among them, an alkali solution dripping device is provided in the grit chamber 1; when it is in working state, the dripping speed of the alkali solution dripping device is 1-2 drops / s, the alkali solution is sodium hydroxide solution, and the pH value of the wastewater is controlled to 7 to achieve the effect of defoaming and reducing the growth of bacterial colonies.

[0052] The intermediate tank is connected to the filter press 3 via the second centrifugal pump 102. The intermediate tank includes two independent first intermediate tanks 21 and second intermediate tanks 22; in this embodiment, the first centrifugal pump 101 and the second centrifugal pump 102 are formed by connecting two centrifugal pumps of the same specifications in parallel.

[0053] The filter press 3 adopts a plate-frame filter press device, and its filter cloth adopts a nylon filter cloth. After the sewage is processed by the filter press 3, a filter cake and a filtrate are obtained. The filtrate can enter the subsequent purification process for purification until it meets the discharge requirements. The purification process can select membrane filtration treatment. After the sewage is processed by the recycling treatment system, the foam and PVDF resin can be effectively removed, thereby reducing the cost of the subsequent purification process.

[0054] Furthermore, after the filter press 3 performs filter press treatment on the wastewater, water is introduced to wash the filter cake in the filter press 3. After the conductivity of the washing water reaches 3-9us / cm, the washed filter cake is sent to the screw machine 4 for PVDF resin recovery treatment; the washing liquid is refluxed to the feeding pipe of the grit chamber 1 through the reflux system to achieve the recovery of PVDF resin in the washing liquid. The filter cake is crushed by the screw machine 4 and then transported to the feeder 5, which is provided with a feeding screw, and the material is delivered to the dryer 61 through the feeding screw.

[0055] After the filter press 3 of this embodiment performs filter press treatment on the wastewater, water is introduced to wash the filter cake in the filter press 3. After the conductivity of the washing water reaches 3-9us / cm, the washed filter cake is sent to the screw machine 4 for PVDF resin recovery treatment; the washing liquid is refluxed to the feeding pipe of the grit chamber 1 through the reflux system to achieve the recovery of PVDF resin in the washing liquid

[0056] The dryer 61 is a blast dryer 61, the top of the dryer 61 is connected to the cyclone separator 7; the dryer 61 is connected to the blast system, wherein the blast system includes a blower 63 and a heater 62, the blower 63 is connected to the heater 62, and the heater 62 is connected to the bottom of the dryer 61; the material can be blown to the top discharge port of the dryer 61 through the blast dryer 61. At the same time, a stirring device is also provided at the bottom of the dryer 61 for stirring the material to reduce adhesion.

[0057] After the material is sent to the cyclone separator 7, it is further dispersed and dried. The material with low water content is lighter and is discharged from the top of the cyclone separator 7 into the sedimentation device 8. The material with high water content stays and continues to be dried under the high-temperature gas from the blast dryer 61 until the moisture content of the material is reduced to a certain range and then discharged. In this embodiment, the moisture content of the material discharged from the cyclone separator 7 is controlled to be ≤2000ppm by adjusting the wind speed, temperature and other parameters of the blast system.

[0058] The top of the sedimentation device 8 intercepts the material through a cloth bag and is connected to the induced draft fan 9. A plurality of parallel baffles 81 are provided inside the sedimentation device 8, and the baffles 81 are located between the air inlet of the sedimentation device 8 and the air outlet connected to the induced draft fan 9. After the material enters the sedimentation device 8, it settles and is collected to obtain PVDF resin powder.

[0059] The above embodiments of the utility model are merely examples for clearly illustrating the utility model, and are not intended to limit the implementation methods of the utility model. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the utility model shall be included in the scope of protection of the claims of the utility model.

Claims

1. A PVDF resin recovery and treatment system in wastewater, characterized in that: It comprises a grit chamber (1), an intermediate chamber, a filter press (3), a dryer (61), a cyclone separator (7) and a sedimentation device (8) which are connected in sequence; a pH regulating device is provided in the grit chamber (1).

2. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: The pH adjusting device is an alkali solution dropping device, and the dropping speed of the alkali solution dropping device is 1-2 drops / s.

3. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: The pH adjusting device is used to adjust the pH value of the grit chamber (1) to 6-8.

4. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: It also includes a magnetic frame, which is located at the water outlet of the middle pool to absorb magnetic particles in the outlet water.

5. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: It also comprises a screw machine (4), wherein the screw machine (4) is connected to the discharge end of the filter press (3) and is used for crushing the filter cake discharged from the filter press (3).

6. The PVDF resin recovery and treatment system in wastewater according to claim 1 or 5, characterized in that: It also comprises a filtrate reflux system, wherein the water inlet end of the filtrate reflux system is connected to the filter press (3), and the water outlet end of the filtrate reflux system is connected to the feed end of the grit chamber (1).

7. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: A stirring device is provided at the bottom of the dryer (61).

8. The PVDF resin recovery and treatment system in wastewater according to claim 1 or 7, characterized in that: It also includes an air blowing system, which includes an air blower (63) and a heater (62). The air blower (63) is connected to the heater (62), and the heater (62) is connected to the bottom of the dryer (61).

9. The PVDF resin recovery and treatment system in wastewater according to claim 1, characterized in that: A plurality of parallel baffles (81) are provided inside the sedimentation device (8), and the baffles (81) are located between the air inlet and the air outlet of the sedimentation device (8).

10. The PVDF resin recovery and treatment system in wastewater according to claim 9, characterized in that: The air outlet of the sedimentation device (8) is connected to an induced draft fan (9).

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