CN107501081B - System and method for recycling perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material - Google Patents
System and method for recycling perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material Download PDFInfo
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Abstract
The invention discloses a system and a method for recycling perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet materials, and belongs to the technical field of organic chemistry recycling. In the invention, the circulating conveying loop is formed by the concentrating device and the gasifying device through the conveying mesh belt, and the recycling circulating loop is formed by the gasifying device, the condensing device, the capturing device and the superheated steam heating furnace through the conveying pipe, so that the procedures of feeding, in-situ concentration, gasifying, condensing and liquid mist capturing are finished in the technology of the recycling system, and the perfluoro caprylic acid recycling work is orderly and effectively carried out. By using the system and the method, the efficiency of recovering the perfluorooctanoic acid is high, the concentration is high, waste gas and waste water containing the perfluorooctanoic acid can not be generated, no additional working procedure is needed, no other raw materials are consumed, and the energy consumption is low.
Description
Technical Field
The invention relates to a system and a method for recycling perfluoro caprylic acid, in particular to a system and a method for recycling perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet materials, and belongs to the technical field of organic chemistry recycling.
Background
Perfluoro caprylic acid is an expensive chemical raw material, is a compound synthesized by manpower, has a melting point of 55-60 ℃ and a boiling point of 189-191 ℃, is easily dissolved in water, and is difficult to degrade naturally. In a process for producing polytetrafluoroethylene dispersion resin particles by polymerizing tetrafluoroethylene monomer (TFE) in an aqueous medium, perfluoro octoic acid is used as a dispersant, the polytetrafluoroethylene dispersion resin particles obtained by polymerization are aqueous wet materials having an average water content of about 40 to 60%, and the perfluoro octoic acid added in the process is still dissolved in water and mixed with the wet materials. In order to obtain qualified polytetrafluoroethylene dispersion resin particles, the polytetrafluoroethylene dispersion resin particles are heated to 200-220 ℃ to enable water and perfluorooctanoic acid in the polytetrafluoroethylene dispersion resin particles to be completely gasified and discharged, and if the gas containing the perfluorooctanoic acid is directly discharged as waste gas, serious environmental pollution is caused, and large economic loss is caused. Therefore, the method for recycling the perfluoro caprylic acid in the polytetrafluoroethylene dispersion resin particle wet material obtained by polymerization has great value for reducing the production cost and reducing the environmental pollution. At present, common recycling technologies are:
the invention with the publication number of CN 1935770A and the patent name of "recovery treatment method of ammonium perfluorooctanoate in the production of polytetrafluoroethylene resin by a dispersion method" and the invention with the publication number of CN103406009A and the patent name of "method and device for recovering the ammonium perfluorooctanoate from the tail gas of the production of fluorine-containing polymer" are all in the drying process of the polymerization process product, the tail gas is cooled, alkali liquor is absorbed, namely perfluoro octoic acid and alkali are subjected to chemical reaction to be converted into perfluoro octoate, then the perfluoro octoate is concentrated, and then is acidified by strong acid, namely perfluoro octoate and acid are reacted to reduce perfluoro octoate, and finally, rectification is carried out to obtain perfluoro octoate with higher concentration, thus completing recovery. The recovery method is long in period and complex in process, and chemical raw materials such as alkali, acid and the like are consumed; in the processes of concentration, rectification and the like, a great deal of energy is consumed additionally. In addition, the consumed alkali and acid raw materials increase the production cost, and after use, the waste materials can generate pollution which need further treatment, and even cause new environmental pollution. The patent publication No. CN102643189A, entitled "System and method for recovering perfluorooctanoic acid from off-gas", discloses that the off-gas generated by drying the polymerization process product is spray cooled by cooled circulating water (or aqueous solution containing perfluorooctanoic acid), wherein water vapor and perfluorooctanoic acid are condensed into liquid to obtain perfluorooctanoic acid solution with mass concentration of 20-30%, the concentration is increased by distillation, and finally the perfluorooctanoic acid solution is rectified to obtain perfluorooctanoic acid with higher concentration, thus the recovery is completed. The method does not use a chemical method for recovery, but the concentration of the obtained perfluoro caprylic acid solution is lower, a great deal of energy is still required for dehydration by subsequent distillation and concentration, further rectification is carried out, and the energy consumption cost is still higher. In the patent with the patent name of CN106823442A, the invention is characterized in that a heat exchanger is used for cooling tail gas to below 30 ℃, the perfluoro caprylic acid is condensed into solid or liquid state to be trapped, and the solid or liquid state is heated by the heat exchanger to be melted and then flows into a storage tank. However, this recovery method does not take into account a large amount of water vapor contained in the tail gas, but when the water vapor is cooled to 30 ℃ or lower, it is completely condensed into liquid water, and the amount of water is sufficient to completely dissolve the perfluorooctanoic acid, and only a low-concentration perfluorooctanoic acid aqueous solution can be obtained, but the perfluorooctanoic acid cannot be efficiently separated, and the technical purpose is not easy to achieve, so that practical engineering application cannot be achieved.
In summary, these technologies are to treat the tail gas containing perfluorooctanoic acid generated during the drying of polytetrafluoroethylene dispersion resin particles to recover perfluorooctanoic acid, which will generate additional raw material consumption and energy consumption, increase the complexity of the recovery process, and have low feasibility.
Disclosure of Invention
The invention aims to solve the problems in the prior art, and provides a system and a method for recycling perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet materials. The technical scheme adopts the technical thought of firstly concentrating in situ and then synchronously fractionating, namely, taking polytetrafluoroethylene dispersion resin particle wet materials as raw materials, using microwaves to enable perfluoro caprylic acid to be concentrated in situ along with the tetrafluoroethylene dispersion resin particles, using the microwaves and superheated steam to heat in a combined way, enabling perfluoro caprylic acid gasification and separation to be synchronously completed, simultaneously carrying out temperature control and cooling, condensing perfluoro caprylic acid, and completing synchronous fractionation. By using the system and the method, the efficiency of recovering the perfluorooctanoic acid is high, the concentration is high, waste gas and waste water containing the perfluorooctanoic acid can not be generated, no additional working procedure is needed, no other raw materials are consumed, and the energy consumption is low.
In order to achieve the technical purpose, the following technical scheme is provided:
A system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet materials comprises a concentration device, a gasification device, a condensation device and a trapping device, wherein the concentration device and the gasification device are connected through a mesh belt conveying device, the mesh belt conveying device comprises a driving roller and a conveying mesh belt, the driving roller drives the conveying mesh belt to move, and the conveying mesh belt passes through the concentration device and the gasification device to form a circulating conveying loop;
the gasification device is connected with a recovery circulation device, the recovery circulation device comprises a condensing device, a trapping device and a superheated steam heating furnace, the condensing device, the trapping device and the superheated steam heating furnace are sequentially connected through conveying pipes, and the gasification device, the condensing device, the trapping device and the superheated steam heating furnace form a recovery circulation closed circuit through the conveying pipes; the condensing device is connected with a first storage tank, and the capturing device is connected with a second storage tank;
a system feeding section is arranged at the front side of a station of the concentration device, the system feeding section is arranged on a conveying mesh belt, and a feeding conveying device is arranged above the station of the system feeding section and is used for continuously inputting initial materials into a recovery system;
the gasification device comprises a gasification device, wherein a gasification device station is arranged on the rear side of the gasification device station, a system discharge section is arranged on a conveying mesh belt and is connected with a third storage tank, and the third storage tank receives polytetrafluoroethylene dispersion resin particles output by the system.
Further, the concentrating device comprises a concentrating device body, and a microwave energy leakage inhibitor I and a vertical air baffle I which are arranged at two sides of the concentrating device body, wherein the concentrating device body is connected with a microwave generator, and a steam exhaust port is arranged at the upper end of the concentrating device body; the concentrating device body comprises a metal shell, wherein the metal shell is made of stainless steel or aluminum, and microwave leakage can be prevented by the metal shell.
Further, the gasification device comprises a gasification device body, and a microwave energy leakage inhibitor II and a vertical air baffle II which are arranged at two sides of the gasification device body, wherein the gasification device body is connected with a microwave generator; the gasification device body is internally provided with a mesh plate, the mesh plate comprises a mesh plate I and a mesh plate II, the mesh plate I is arranged at the top of the gasification device body, and the mesh plate II is arranged at the bottom of the gasification device body; the upper end of the gasification device body is provided with an air outlet cover, the air outlet cover is provided with an air outlet, the lower end of the gasification device body is provided with an air inlet cover, and the air inlet cover is provided with an air inlet; the gasification device body comprises a metal shell, the metal shell is made of stainless steel or aluminum, and the metal shell can prevent microwave leakage; one end of the recovery circulation device is connected with the air outlet, and the other end of the recovery circulation device is connected with the air inlet.
Further, a circulating fan is arranged between the trapping device and the superheated steam heating furnace, and the circulating fan is arranged on the conveying pipe; be equipped with tee bend I and tee bend II between circulating fan and superheated steam heating furnace, tee bend I and tee bend II all set up on the steam delivery pipe, and tee bend I even has discharge valve, and tee bend II even has the inflation valve.
Further, the condensing means comprises one or more of a tube cooler, a plate cooler and a spray cooler.
Further, the trapping device comprises one or more of a damping adsorption purifier, an electrostatic purifier, a screening purifier and a centrifugal purifier.
Further, the conveying mesh belt is made of polytetrafluoroethylene glass fiber.
A method for recovering perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material comprises the following specific steps:
A. feeding material
Using polytetrafluoroethylene dispersion resin particle wet materials as raw materials, and uniformly distributing initial materials to a conveying mesh belt of a system feeding section by using a feeding conveying device;
B. in situ concentration
C, conveying the raw materials supplied in the step A into a concentrating device through a conveying mesh belt, enabling the raw materials to travel in the concentrating device for 5-20min, enabling the raw materials to be subjected to microwave action for 5-20min, enabling water in the raw materials to be vaporized into water vapor, and naturally overflowing from a vapor discharge port to obtain a concentrated material, namely a material I;
C. Microwave and superheated steam combined gasification
B, inputting the concentrated material I in the step B into a gasification device through a conveying mesh belt, allowing the material I to travel in the gasification device for 10-25min, simultaneously heating the material I to 195-240 ℃ under the action of microwaves and high-temperature superheated steam for 10-25min, allowing the completely vaporized perfluoro caprylic acid and steam to be discharged through the mesh plate I, an air outlet cover and an air outlet in sequence under the action of a circulating fan;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section through a conveying mesh belt and then flow into a third storage tank for other use;
D. condensation
C, conveying the gaseous perfluorooctanoic acid and water vapor discharged from the step C to a condensing device under the traction action of a circulating fan, cooling the gaseous perfluorooctanoic acid to 120-160 ℃ in the condensing device, converting the gaseous perfluorooctanoic acid into liquid perfluorooctanoic acid, attaching the liquid perfluorooctanoic acid in the condensing device, finally flowing into a first storage tank, and collecting and fractionating to obtain a perfluorooctanoic acid product; and a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist along with water vapor through a conveying pipe;
E. liquid mist trapping
The liquid-state vaporous perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device through a conveying pipe, the liquid-state vaporous perfluorooctanoic acid is trapped in the trapping device, the liquid-state vaporous perfluorooctanoic acid is collected through a second storage tank, and after fractionation, a perfluorooctanoic acid product and clean water vapor are obtained, and the clean water vapor is discharged through the conveying pipe;
F. Steam heating and circulation
And E, conveying clean steam discharged in the step E to a superheated steam heating furnace through a conveying pipe, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet through the conveying pipe, and sequentially passing through an air inlet cover, a mesh plate II and a conveying mesh belt to diffuse into a material I to heat the material I.
Further, the polytetrafluoroethylene dispersion resin particle wet material used as a raw material comprises polytetrafluoroethylene dispersion resin particles with a water content of 40-60%.
Further, the recovery rate of the perfluorooctanoic acid is more than 95%, the concentration of the perfluorooctanoic acid reaches 95-99%, and the recovery period of the system is 20-50min, wherein in the step B, 91-96% of water in the raw material is vaporized into water vapor, the temperature of the raw material and the perfluorooctanoic acid contained in the raw material is less than or equal to 100 ℃, and after in-situ concentration, the concentration of the perfluorooctanoic acid is improved by 11-25 times; in the step D, the recovery rate of the perfluorooctanoic acid accounts for 80-95% of the total recovery rate, and the rest part is recovered by the step E; the steam heating and circulating process in the step F is adopted, and the energy is saved by 80-90%.
By adopting the technical scheme, the beneficial technical effects brought are as follows:
1) In the invention, the concentration device and the gasification device form a circulating conveying loop through a conveying net belt, and the gasification device, the condensation device, the trapping device and the superheated steam heating furnace form a recycling closed loop through conveying pipes, so that the perfluoro caprylic acid recycling process is orderly and effectively completed. Under the synergistic effect of the system and the method, the recovery rate of the perfluorooctanoic acid is high and can reach more than 95 percent; the concentration of the recovered perfluoro caprylic acid is high and can reach 95-99 percent; other raw materials are not added in the recovery system, and few impurities are introduced, so that the perfluoro caprylic acid with high purity and high reaction activity can be obtained without rectification again, and the reuse can be satisfied; the gas exhausted by the exhaust valve has no pollution, and adverse effects on the environment are effectively avoided; meanwhile, the recovery period of the perfluoro caprylic acid is 20-50min, the period is short, the recovery rate is more than 95%, the recovery system is high in efficiency, the automatic feedback control is easy, and the method is suitable for large-scale industrial production;
2) In the step B, the raw material has high water content and high microwave loss, but is limited by the boiling point of normal pressure water, the temperature of the raw material and the perfluoro caprylic acid contained in the raw material is less than or equal to 100 ℃, and is far lower than the boiling point of the perfluoro caprylic acid of 189-191 ℃, so that the perfluoro caprylic acid can be rapidly and efficiently concentrated in situ, and the vapor does not contain the perfluoro caprylic acid and can be directly discharged or used as the vapor. Through the action of microwaves, the concentration efficiency is high, 91-96% of water in the raw materials is vaporized into water vapor, the concentration of the perfluorooctanoic acid is improved by 11-25 times, the concentration period is short, the period is 5-20min, and the recovery efficiency of the perfluorooctanoic acid is improved;
3) In the step C, the polytetrafluoroethylene has extremely low microwave loss, so that the raw materials are difficult to rise to higher temperature, and high-temperature superheated steam is used as an auxiliary material; under the combined action of microwaves and high-temperature multi-heat steam, the raw materials are heated rapidly and efficiently, the temperature of the raw materials is increased to 195-240 ℃, the temperature is higher than the boiling point of the perfluorooctanoic acid (189-191 ℃), the perfluorooctanoic acid can be gasified rapidly and thoroughly, and the gaseous perfluorooctanoic acid is separated from the raw materials along with the steam;
4) In step D, the gaseous perfluorooctanoic acid is cooled to 120-160 ℃, the temperature is lower than the boiling point 189-191 ℃ of the perfluorooctanoic acid and is higher than the boiling point 100 ℃ of normal pressure water, so that the gaseous perfluorooctanoic acid can be completely condensed, the water vapor is not condensed, and the vaporization latent heat of the water vapor is not lost; in addition, the trapping device in the step E is additionally arranged, so that a small amount of condensed perfluorooctanoic acid liquid mist in the water vapor can be further separated. Therefore, the gasification device, the condensing device, the trapping device and the superheated steam heating furnace form a recycling closed circuit through the conveying pipe, and the high-purity and high-concentration perfluorooctanoic acid can be obtained through the recycling closed circuit, and clean water vapor can be separated for subsequent recycling, so that a large amount of energy sources can be effectively saved, the performance of raw materials is prevented from being damaged, and qualified polytetrafluoroethylene dispersion resin particle finished products can be obtained;
5) In the invention, when the gasification device operates, clean superheated steam is filled into the superheated steam circulation device through the tee joint II and the charging valve for gasification, condensation, liquid mist trapping and steam heating circulation; the filled steam does not contain dust or other impurities, so that the purity of the recovered perfluorooctanoic acid is not affected, and the quality of raw materials is not affected. In the step C, the steam pressure should be equivalent to atmospheric pressure range, because the moisture in the material I is vaporized continuously, the steam in the gasification, condensation and trapping circulation device is increased, the increased steam can be discharged through the tee joint I and the exhaust valve, the pressure of the recovery circulation system is kept stable, and in addition, because the steam is gasified and purified by the trapping device before being discharged, no harmful environmental pollutants are contained, and the steam can be directly discharged or used. The steam discharged through the exhaust valve can be directly discharged, can be used as industrial steam after being heated and pressurized, and can also be used for recovering the latent heat through a heat exchanger, and the condensed water generated by the steam does not contain perfluoro caprylic acid and can be directly discharged, or can be used as industrial production water after being treated according to other requirements;
6) In the step B, C, the period of concentrating and gasifying materials is shorter, the time for completing the step B is 5-20min, the time for completing the step C is 10-25min, the period for completing the concentration and gasification is 15-45min, and a complex tail gas treatment device is not needed, so that the manufacturing cost of equipment can be reduced, the production process is simplified, and the production efficiency is improved.
Drawings
FIG. 1 is a schematic view of a recycling system according to the present invention
In the figure, 1, a concentrating device, 101, a concentrating device body, 102, a microwave energy leakage inhibitor I, 103, a vertical air baffle I, 104, a steam outlet, 2, a gasification device, 201, a gasification device body, 202, a microwave energy leakage inhibitor II, 203, a vertical air baffle II, 204, a mesh plate I, 205, a mesh plate II, 3, an air outlet cover, 4, an air outlet, 5, an air inlet cover, 6, an air inlet, 7, a recycling circulation device, 701, a condensing device, 702, a capturing device, 703, a circulating fan, 704, a superheated steam heating furnace, 705, a conveying pipe, 8, a first storage tank, 9, a second storage tank, 10, a mesh belt conveying device, 1001, a driving roller, 1002, a conveying mesh belt, 11, a feeding conveying device, 12, a system feeding section, 13, a system discharging section, 14, a third storage tank, 15, a tee I, 16, a tee II, 17, an exhaust valve, 18, an inflation valve, 19 and a microwave generator are shown.
Detailed Description
In the following, it is obvious that the embodiments described are only some embodiments of the present invention, but not all embodiments, by clearly and completely describing the technical solutions in the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
A system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet materials comprises a concentration device 1, a gasification device 2, a condensation device 701 and a trapping device 702, wherein the concentration device 1 and the gasification device 2 are connected through a mesh belt conveying device 10, the mesh belt conveying device 10 comprises a driving roller 1001 and a conveying mesh belt 1002, the driving roller 1001 drives the conveying mesh belt 1002 to move, and the conveying mesh belt 1002 passes through the concentration device 1 and the gasification device 2 to form a circulating conveying loop; the gasification device 2 is connected with a recovery circulation device 7, the recovery circulation device 7 comprises a condensation device 701, a trapping device 702 and a superheated steam heating furnace 704, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 are sequentially connected through a conveying pipe 705, and the gasification device 2, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 form a recovery circulation closed circuit through the conveying pipe 705; the condensing device 701 is connected with a first storage tank 8, and the capturing device 702 is connected with a second storage tank 9; a system feeding section 12 is arranged at the front side of a station of the concentration device 1, the system feeding section 12 is arranged on a conveying mesh belt 1002, a feeding and conveying device 11 is arranged above the station of the system feeding section 12, and the feeding and conveying device 11 continuously inputs initial materials for a recovery system; the gasification device 2 station rear side is equipped with system's ejection of compact section 13, and system's ejection of compact section 13 sets up on the transportation guipure 1002, and system's ejection of compact section 13 connects third storage tank 14, and the polytetrafluoroethylene dispersion resin granule of system output is received to third storage tank 14.
Further, the concentrating device 1 comprises a concentrating device body 101, and a microwave energy leakage inhibitor I102 and a vertical air baffle I103 which are arranged on two sides of the concentrating device body 101, wherein the concentrating device body 101 is connected with a microwave generator 19, and a steam exhaust port 104 is arranged at the upper end of the concentrating device body 101; the concentrating device body 101 comprises a metal housing made of stainless steel or aluminum, and the metal housing can prevent microwave leakage.
Further, the gasification device 2 comprises a gasification device body 201, and a microwave energy leakage inhibitor II 202 and a vertical air baffle II 203 which are arranged at two sides of the gasification device body 201, wherein the gasification device body 201 is connected with a microwave generator 19; the gasification device body 201 is internally provided with a mesh plate, the mesh plate comprises a mesh plate I204 and a mesh plate II 205, the mesh plate I204 is arranged at the top of the gasification device body 201, and the mesh plate II 205 is arranged at the bottom of the gasification device body 201; the upper end of the gasification device body 201 is provided with an air outlet cover 3, the air outlet cover 3 is provided with an air outlet 4, the lower end of the gasification device body 201 is provided with an air inlet cover 5, and the air inlet cover 5 is provided with an air inlet 6; the gasification device body 201 comprises a metal shell, and the metal shell is made of stainless steel or aluminum, so that the metal shell can prevent microwave leakage; one end of the recovery circulation device 7 is connected with the air outlet 4, and the other end is connected with the air inlet 6.
Further, a circulating fan 703 is arranged between the trapping device 702 and the superheated steam heating furnace 704, and the circulating fan 703 is arranged on the conveying pipe 705; a tee joint I15 and a tee joint II 16 are arranged between the circulating fan 703 and the superheated steam heating furnace 704, the tee joint I15 and the tee joint II 16 are arranged on the steam conveying pipe 705, the tee joint I15 is connected with an exhaust valve 17, and the tee joint II 16 is connected with an inflation valve 18.
Further, the condensing unit 701 is a tube cooler.
Further, the trapping device 702 is a screen type purifier and a centrifugal type purifier.
A method for recovering perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material comprises the following specific steps:
A. feeding material
Using polytetrafluoroethylene dispersion resin particle wet materials as raw materials, and uniformly distributing initial materials on a conveying mesh belt 1002 of a system feeding section 12 by a feeding conveying device 11;
B. in situ concentration
The raw materials supplied in the step A are conveyed into a concentrating device 1 through a conveying mesh belt 1002, the raw materials move in the concentrating device 1 for 5min and are subjected to the action of microwaves for 5min, water in the raw materials is vaporized into water vapor, and the water vapor naturally overflows from a vapor discharge port 104, so that a concentrated material, namely a material I, is obtained;
C. microwave and superheated steam combined gasification
B, inputting the concentrated material I in the step B into a gasification device 2 through a conveying mesh belt 1002, allowing the material I to move in the gasification device 2 for 10min, heating the material I to 195 ℃ under the action of microwaves and high-temperature superheated steam for 10min, allowing the completely vaporized perfluoro caprylic acid and steam to be discharged through a mesh plate I204, an air outlet cover 3 and an air outlet 4 in sequence under the action of a circulating fan 703;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 120 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701, and finally flows into a first storage tank 8, and the perfluorooctanoic acid product is obtained after collection and fractionation; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, collected by a second storage tank 9, fractionated to obtain a perfluorooctanoic acid product and clean water vapor, and the clean water vapor is discharged through the conveying pipe 705;
F. Steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the polytetrafluoroethylene dispersion resin particle wet material as a raw material includes polytetrafluoroethylene dispersion resin particles having a water content of 40%.
Further, the recovery rate of the perfluorooctanoic acid is 95%, the concentration of the perfluorooctanoic acid reaches 95%, and the system recovery period is 30min, wherein in the step B, 91% of water in the raw materials is vaporized into water vapor, the temperature of the raw materials and the perfluorooctanoic acid contained in the raw materials is 100 ℃, and the concentration of the perfluorooctanoic acid is improved by 11 times after in-situ concentration; in the step D, the recovery rate of the perfluorooctanoic acid accounts for 95 percent of the total recovery, and the rest part is recovered by the step E; the steam heating and circulating process in the step F is adopted, so that the energy is saved by 80%.
Example 2
A system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet materials comprises a concentration device 1, a gasification device 2, a condensation device 701 and a trapping device 702, wherein the concentration device 1 and the gasification device 2 are connected through a mesh belt conveying device 10, the mesh belt conveying device 10 comprises a driving roller 1001 and a conveying mesh belt 1002, the driving roller 1001 drives the conveying mesh belt 1002 to move, and the conveying mesh belt 1002 passes through the concentration device 1 and the gasification device 2 to form a circulating conveying loop; the gasification device 2 is connected with a recovery circulation device 7, the recovery circulation device 7 comprises a condensation device 701, a trapping device 702 and a superheated steam heating furnace 704, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 are sequentially connected through a conveying pipe 705, and the gasification device 2, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 form a recovery circulation closed circuit through the conveying pipe 705; the condensing device 701 is connected with a first storage tank 8, and the capturing device 702 is connected with a second storage tank 9; a system feeding section 12 is arranged at the front side of a station of the concentration device 1, the system feeding section 12 is arranged on a conveying mesh belt 1002, a feeding and conveying device 11 is arranged above the station of the system feeding section 12, and the feeding and conveying device 11 continuously inputs initial materials for a recovery system; the gasification device 2 station rear side is equipped with system's ejection of compact section 13, and system's ejection of compact section 13 sets up on the transportation guipure 1002, and system's ejection of compact section 13 connects third storage tank 14, and the polytetrafluoroethylene dispersion resin granule of system output is received to third storage tank 14.
Further, the concentrating device 1 comprises a concentrating device body 101, and a microwave energy leakage inhibitor I102 and a vertical air baffle I103 which are arranged on two sides of the concentrating device body 101, wherein the concentrating device body 101 is connected with a microwave generator 19, and a steam exhaust port 104 is arranged at the upper end of the concentrating device body 101; the concentrating device body 101 comprises a metal housing made of stainless steel or aluminum, and the metal housing can prevent microwave leakage.
Further, the gasification device 2 comprises a gasification device body 201, and a microwave energy leakage inhibitor II 202 and a vertical air baffle II 203 which are arranged at two sides of the gasification device body 201, wherein the gasification device body 201 is connected with a microwave generator 19; the gasification device body 201 is internally provided with a mesh plate, the mesh plate comprises a mesh plate I204 and a mesh plate II 205, the mesh plate I204 is arranged at the top of the gasification device body 201, and the mesh plate II 205 is arranged at the bottom of the gasification device body 201; the upper end of the gasification device body 201 is provided with an air outlet cover 3, the air outlet cover 3 is provided with an air outlet 4, the lower end of the gasification device body 201 is provided with an air inlet cover 5, and the air inlet cover 5 is provided with an air inlet 6; the gasification device body 201 comprises a metal shell, and the metal shell is made of stainless steel or aluminum, so that the metal shell can prevent microwave leakage; one end of the recovery circulation device 7 is connected with the air outlet 4, and the other end is connected with the air inlet 6.
Further, the condensing device 701 is a spray cooler.
Further, the trapping device 702 is a combination of an electrostatic purifier and a sieving purifier.
Further, the conveying mesh belt 1002 is made of polytetrafluoroethylene glass fiber.
A method for recovering perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material comprises the following specific steps:
A. feeding material
Using polytetrafluoroethylene dispersion resin particle wet materials as raw materials, and uniformly distributing initial materials on a conveying mesh belt 1002 of a system feeding section 12 by a feeding conveying device 11;
B. in situ concentration
The raw materials supplied in the step A are conveyed into a concentrating device 1 through a conveying mesh belt 1002, the raw materials move for 20min in the concentrating device 1 and are subjected to the action of microwaves for 20min, water in the raw materials is vaporized into water vapor, and the water vapor naturally overflows from a vapor discharge port 104, so that a concentrated material, namely a material I, is obtained;
C. microwave and superheated steam combined gasification
B, inputting the concentrated material I in the step B into a gasification device 2 through a conveying mesh belt 1002, enabling the material I to move in the gasification device 2 for 25min, simultaneously heating the material I to 240 ℃ under the action of microwaves and high-temperature superheated steam for 25min, enabling the completely vaporized perfluoro caprylic acid and steam to be discharged through a mesh plate I204, an air outlet cover 3 and an air outlet 4 in sequence under the action of a circulating fan 703;
After the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 160 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701, and finally flows into a first storage tank 8, and the perfluorooctanoic acid product is obtained after collection and fractionation; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, collected by a second storage tank 9, fractionated to obtain a perfluorooctanoic acid product and clean water vapor, and the clean water vapor is discharged through the conveying pipe 705;
F. steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the polytetrafluoroethylene dispersion resin particle wet material as a raw material includes polytetrafluoroethylene dispersion resin particles having a water content of 60%.
Further, the recovery rate of the perfluorooctanoic acid is 98%, the concentration of the perfluorooctanoic acid reaches 99%, and the recovery period of the system is 50min, wherein in the step B, 96% of water in the raw materials is vaporized into water vapor, the temperature of the raw materials and the perfluorooctanoic acid contained in the raw materials is 98 ℃, and the concentration of the perfluorooctanoic acid is improved by 25 times after in-situ concentration; in the step D, the recovery rate of the perfluorooctanoic acid accounts for 80 percent of the total recovery rate, and the rest part is recovered by the step E; the steam heating and circulating process in the step F is adopted, so that the energy is saved by 90%.
Example 3
As shown in fig. 1: a system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet materials comprises a concentration device 1, a gasification device 2, a condensation device 701 and a trapping device 702, wherein the concentration device 1 and the gasification device 2 are connected through a mesh belt conveying device 10, the mesh belt conveying device 10 comprises a driving roller 1001 and a conveying mesh belt 1002, the driving roller 1001 drives the conveying mesh belt 1002 to move, and the conveying mesh belt 1002 passes through the concentration device 1 and the gasification device 2 to form a circulating conveying loop; the gasification device 2 is connected with a recovery circulation device 7, the recovery circulation device 7 comprises a condensation device 701, a trapping device 702 and a superheated steam heating furnace 704, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 are sequentially connected through a conveying pipe 705, and the gasification device 2, the condensation device 701, the trapping device 702 and the superheated steam heating furnace 704 form a recovery circulation closed circuit through the conveying pipe 705; the condensing device 701 is connected with a first storage tank 8, and the capturing device 702 is connected with a second storage tank 9; a system feeding section 12 is arranged at the front side of a station of the concentration device 1, the system feeding section 12 is arranged on a conveying mesh belt 1002, a feeding and conveying device 11 is arranged above the station of the system feeding section 12, and the feeding and conveying device 11 continuously inputs initial materials for a recovery system; the gasification device 2 station rear side is equipped with system's ejection of compact section 13, and system's ejection of compact section 13 sets up on the transportation guipure 1002, and system's ejection of compact section 13 connects third storage tank 14, and the polytetrafluoroethylene dispersion resin granule of system output is received to third storage tank 14.
Further, the concentrating device 1 comprises a concentrating device body 101, and a microwave energy leakage inhibitor I102 and a vertical air baffle I103 which are arranged on two sides of the concentrating device body 101, wherein the concentrating device body 101 is connected with a microwave generator 19, and a steam exhaust port 104 is arranged at the upper end of the concentrating device body 101; the concentrating device body 101 comprises a metal housing made of stainless steel or aluminum, and the metal housing can prevent microwave leakage.
Further, the gasification device 2 comprises a gasification device body 201, and a microwave energy leakage inhibitor II 202 and a vertical air baffle II 203 which are arranged at two sides of the gasification device body 201, wherein the gasification device body 201 is connected with a microwave generator 19; the gasification device body 201 is internally provided with a mesh plate, the mesh plate comprises a mesh plate I204 and a mesh plate II 205, the mesh plate I204 is arranged at the top of the gasification device body 201, and the mesh plate II 205 is arranged at the bottom of the gasification device body 201; the upper end of the gasification device body 201 is provided with an air outlet cover 3, the air outlet cover 3 is provided with an air outlet 4, the lower end of the gasification device body 201 is provided with an air inlet cover 5, and the air inlet cover 5 is provided with an air inlet 6; the gasification device body 201 comprises a metal shell, and the metal shell is made of stainless steel or aluminum, so that the metal shell can prevent microwave leakage; one end of the recovery circulation device 7 is connected with the air outlet 4, and the other end is connected with the air inlet 6.
Further, a circulating fan 703 is arranged between the trapping device 702 and the superheated steam heating furnace 704, and the circulating fan 703 is arranged on the conveying pipe 705; a tee joint I15 and a tee joint II 16 are arranged between the circulating fan 703 and the superheated steam heating furnace 704, the tee joint I15 and the tee joint II 16 are arranged on the steam conveying pipe 705, the tee joint I15 is connected with an exhaust valve 17, and the tee joint II 16 is connected with an inflation valve 18.
Further, the condensing unit 701 is a combination of a plate cooler and a spray cooler.
Further, the trapping device 702 is a combination of an electrostatic purifier and a centrifugal purifier.
Further, the conveying mesh belt 1002 is made of polytetrafluoroethylene glass fiber.
A method for recovering perfluoro caprylic acid from polytetrafluoroethylene dispersion resin particle wet material comprises the following specific steps:
A. feeding material
Using polytetrafluoroethylene dispersion resin particle wet materials as raw materials, and uniformly distributing initial materials on a conveying mesh belt 1002 of a system feeding section 12 by a feeding conveying device 11;
B. in situ concentration
The raw materials supplied in the step A are conveyed into a concentrating device 1 through a conveying mesh belt 1002, the raw materials move for 13min in the concentrating device 2 and are subjected to the action of microwaves for 13min, water in the raw materials is vaporized into water vapor, and the water vapor naturally overflows from a vapor discharge port 104, so that a concentrated material, namely a material I, is obtained;
C. Microwave and superheated steam combined gasification
B, inputting the concentrated material I in the step B into a gasification device 2 through a conveying mesh belt 1002, enabling the material I to move in the gasification device 2 for 18min, simultaneously heating the material I to 210 ℃ under the action of microwaves and high-temperature superheated steam for 18min, enabling the completely vaporized perfluoro caprylic acid and steam to be discharged through a mesh plate I204, an air outlet cover 3 and an air outlet 4 in sequence under the action of a circulating fan 703;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 140 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701, and finally flows into a first storage tank 8, and the perfluorooctanoic acid product is obtained after collection and fractionation; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, collected by a second storage tank 9, fractionated to obtain a perfluorooctanoic acid product and clean water vapor, and the clean water vapor is discharged through the conveying pipe 705;
F. Steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the polytetrafluoroethylene dispersion resin particle wet material as a raw material includes polytetrafluoroethylene dispersion resin particles having a water content of 50%.
Example 4
In the system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet material of example 3, 10kg of polytetrafluoroethylene dispersion resin particle wet material was used as a raw material, and drying was performed, specifically as follows:
A. feeding material
Taking 10kg of polytetrafluoroethylene dispersion resin particle wet materials with the water content of 40% as raw materials, and uniformly distributing the initial materials on a conveying mesh belt 1002 of a system feeding section 12 by a feeding conveying device 11;
B. in situ concentration
Conveying 10kg of raw materials supplied in the step A into a concentrating device 1 through a conveying mesh belt 1002, enabling the raw materials to move for 13min in the concentrating device 1, enabling the raw materials to be subjected to microwave action for 13min at the same time, enabling water in the raw materials to be vaporized into water vapor, and enabling the water in the raw materials to naturally overflow from a vapor outlet 104 to obtain concentrated materials, namely 6.24kg of materials I, enabling 94% of water in the raw materials to be vaporized into water vapor, enabling the temperature of the raw materials and the temperature of perfluorooctanoic acid contained in the raw materials to be 94 ℃, and enabling the concentration of the perfluorooctanoic acid to be improved by 18 times after in-situ concentration;
C. Microwave and superheated steam combined gasification
Inputting 6.24kg of the concentrated material I in the step B into a gasification device 2 through a conveying mesh belt 1002, allowing the material I to move in the gasification device 2 for 18min, heating the material I to 210 ℃ under the action of microwaves and high-temperature superheated steam for 18min, allowing the completely vaporized perfluoro caprylic acid and steam to be discharged through a mesh plate I204, an air outlet cover 3 and an air outlet 4 in sequence under the action of a circulating fan 703;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 140 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701 and finally flows into a first storage tank 8, 68g of perfluorooctanoic acid product is obtained after collection and fractionation, and the recovery rate of the perfluorooctanoic acid is 88% of the total recovery rate; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. Liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, the liquid-state mist perfluorooctanoic acid is collected by a second storage tank 9, 9.2g of perfluorooctanoic acid products and clean water vapor are obtained after fractionation, and the clean water vapor is discharged through the conveying pipe 705;
F. steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the recovery rate of the perfluorooctanoic acid is 96.6%, the concentration of the recovered perfluorooctanoic acid reaches 97%, and the system recovery period is 38min.
Example 5
In the system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet material of example 3, 20kg of polytetrafluoroethylene dispersion resin particle wet material was used as a raw material, and drying was performed, specifically as follows:
A. feeding material
Taking 20kg of polytetrafluoroethylene dispersion resin particle wet materials with the water content of 60% as raw materials, and uniformly distributing the initial materials on a conveying mesh belt 1002 of a system feeding section 12 by a feeding conveying device 11;
B. In situ concentration
Conveying 20kg of raw materials supplied in the step A into a concentrating device 1 through a conveying mesh belt 1002, enabling the raw materials to move in the concentrating device 1 for 20min, enabling the raw materials to be subjected to microwave action for 20min, enabling water in the raw materials to be vaporized into water vapor, and enabling the water in the raw materials to naturally overflow from a vapor outlet 104 to obtain concentrated materials, namely 8.48kg of materials I, wherein 96% of water in the raw materials is vaporized into water vapor, enabling the temperature of the raw materials and the temperature of perfluorooctanoic acid contained in the raw materials to be 98 ℃, and enabling the concentration of the perfluorooctanoic acid to be improved by 25 times after in-situ concentration;
C. microwave and superheated steam combined gasification
Inputting 8.48kg of the concentrated material I in the step B into a gasification device 2 through a conveying mesh belt 1002, allowing the material I to move in the gasification device 2 for 25min, heating the material I to 240 ℃ under the action of microwaves and high-temperature superheated steam for 25min, allowing the completely vaporized perfluoro caprylic acid and steam to be discharged through a mesh plate I204, an air outlet cover 3 and an air outlet 4 in sequence under the action of a circulating fan 703;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 160 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701 and finally flows into a first storage tank 8, 188g of perfluorooctanoic acid products are obtained after collection and fractionation, and the recovery rate of the perfluorooctanoic acid accounts for 80% of the total recovery rate; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. Liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, collected by a second storage tank 9, fractionated to obtain 47g of perfluorooctanoic acid product and clean water vapor, and the clean water vapor is discharged through the conveying pipe 705;
F. steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the recovery rate of the perfluorooctanoic acid is 98%, the concentration of the perfluorooctanoic acid reaches 99%, and the system recovery period is 50min.
Example 6
Based on the system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet material in example 3, 100kg of polytetrafluoroethylene dispersion resin particle wet material is used as a raw material, and drying is performed, specifically comprising the following steps:
A. feeding material
Taking 100kg of polytetrafluoroethylene dispersion resin particle wet material with the water content of 55% as a raw material, and uniformly distributing the initial material on a conveying mesh belt 1002 of a system feeding section 12 by using a feeding conveying device 11;
B. In situ concentration
Conveying 100kg of raw materials supplied in the step A into a concentrating device 1 through a conveying mesh belt 1002, enabling the raw materials to move in the concentrating device 1 for 5min, enabling the raw materials to be subjected to microwave action for 5min, enabling water in the raw materials to be vaporized into water vapor, and enabling the water in the raw materials to naturally overflow from a vapor outlet 104 to obtain a concentrated material, namely 49.95kg of a material I, wherein 91% of water in the raw materials is vaporized into water vapor, enabling the temperature of the raw materials and the temperature of perfluorooctanoic acid contained in the raw materials to be 100 ℃, and enabling the concentration of the perfluorooctanoic acid to be 11 times after in-situ concentration;
C. microwave and superheated steam combined gasification
49.95kg of the concentrated material I in the step B is input into the gasification device 2 through the conveying mesh belt 1002, the material I moves for 10min in the gasification device 2 and is subjected to the action of microwaves and high-temperature superheated steam for 10min, the material I is heated to 195 ℃, and the completely vaporized perfluoro caprylic acid and steam are discharged through the mesh plate I204, the air outlet cover 3 and the air outlet 4 in sequence under the action of the circulating fan 703;
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section 13 through a conveying mesh belt 1002 and then flow into a third storage tank 14 for other use;
D. condensation
The gaseous perfluorooctanoic acid and the water vapor discharged from the step C are conveyed to a condensing device 701 under the traction action of a circulating fan 703, the gaseous perfluorooctanoic acid is cooled to 120 ℃ in the condensing device 701, the gaseous perfluorooctanoic acid is converted into liquid perfluorooctanoic acid, the liquid perfluorooctanoic acid is attached in the condensing device 701 and finally flows into a first storage tank 8, 1045g of perfluorooctanoic acid product is obtained after collection and fractionation, and the recovery rate of the perfluorooctanoic acid accounts for 95% of the total recovery; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through the delivery tube 705;
E. Liquid mist trapping
The liquid-state mist perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device 702 through a conveying pipe 705, the liquid-state mist perfluorooctanoic acid is trapped in the trapping device 702, collected by a second storage tank 9, fractionated to obtain a perfluorooctanoic acid product 55g and clean water vapor, and the clean water vapor is discharged through the conveying pipe 705;
F. steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace 704 through a conveying pipe 705, heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet 6 through the conveying pipe 705, and sequentially passing through an air inlet cover 5, a mesh plate II 205 and a conveying mesh belt 1002 to diffuse into a material I to heat the material I by the high-temperature superheated steam.
Further, the recovery rate of the perfluorooctanoic acid is 95%, the concentration of the perfluorooctanoic acid reaches 95%, and the system recovery period is 30min.
Claims (10)
1. A system for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion resin particle wet stock, characterized by: the device comprises a concentration device (1), a gasification device (2), a condensation device (701) and a trapping device (702), wherein the concentration device (1) and the gasification device (2) are connected through a mesh belt conveying device (10), the mesh belt conveying device (10) comprises a driving roller (1001) and a conveying mesh belt (1002), the driving roller (1001) drives the conveying mesh belt (1002) to move, and the conveying mesh belt (1002) passes through the concentration device (1) and the gasification device (2) to form a circulating conveying loop;
The gasification device (2) is connected with a recovery circulation device (7), the recovery circulation device (7) comprises a condensation device (701), a trapping device (702) and a superheated steam heating furnace (704), the condensation device (701), the trapping device (702) and the superheated steam heating furnace (704) are sequentially connected through a conveying pipe (705), and the gasification device (2), the condensation device (701), the trapping device (702) and the superheated steam heating furnace (704) form a recovery circulation closed circuit through the conveying pipe (705); the condensing device (701) is connected with a first storage tank (8), and the trapping device (702) is connected with a second storage tank (9);
a system feeding section (12) is arranged at the front side of a station of the concentration device (1), the system feeding section (12) is arranged on a conveying mesh belt (1002), and a feeding conveying device (11) is arranged above the station of the system feeding section (12); the concentrating device (1) comprises a concentrating device body (101), microwave energy leakage suppressors I (102) and vertical air baffles I (103) which are arranged on two sides of the concentrating device body (101), and the concentrating device body (101) is connected with a microwave generator (19);
a system discharging section (13) is arranged at the rear side of the station of the gasification device (2), the system discharging section (13) is arranged on a conveying mesh belt (1002), and the system discharging section (13) is connected with a third storage tank (14); the gasification device (2) comprises a gasification device body (201), microwave energy leakage suppressors II (202) and vertical air baffle II (203) which are arranged on two sides of the gasification device body (201), and the gasification device body (201) is connected with a microwave generator (19).
2. The system for recovering perfluorooctanoic acid according to claim 1, wherein: the upper end of the concentrating device body (101) is provided with a steam exhaust port (104); the concentrator body (101) includes a metal housing.
3. The system for recovering perfluorooctanoic acid according to claim 1, wherein: the gasification device comprises a gasification device body (201), and is characterized in that a mesh plate is arranged in the gasification device body (201), the mesh plate comprises a mesh plate I (204) and a mesh plate II (205), the mesh plate I (204) is arranged at the top of the gasification device body (201), and the mesh plate II (205) is arranged at the bottom of the gasification device body (201); an air outlet cover (3) is arranged at the upper end of the gasification device body (201), an air outlet (4) is arranged on the air outlet cover (3), an air inlet cover (5) is arranged at the lower end of the gasification device body (201), and an air inlet (6) is arranged on the air inlet cover (5); the gasification device body (201) comprises a metal shell; one end of the recovery circulation device (7) is connected with the air outlet (4), and the other end is connected with the air inlet (6).
4. The system for recovering perfluorooctanoic acid according to claim 1, wherein: a circulating fan (703) is arranged between the trapping device (702) and the superheated steam heating furnace (704), and the circulating fan (703) is arranged on the conveying pipe (705); be equipped with tee bend I (15) and tee bend II (16) between circulation fan (703) and superheated steam heating furnace (704), tee bend I (15) and tee bend II (16) all set up on steam delivery pipe (705), and tee bend I (15) even have discharge valve (17), and tee bend II (16) even have inflation valve (18).
5. The system for recovering perfluorooctanoic acid according to claim 1, wherein: the condensing means (701) comprises one or more of a tube cooler, a plate cooler and a spray cooler.
6. The system for recovering perfluorooctanoic acid according to claim 1, wherein: the capture device (702) includes one or more of a dampened adsorption purifier, an electrostatic purifier, a screen purifier, and a centrifugal purifier.
7. The system for recovering perfluorooctanoic acid according to claim 1, wherein: the conveying mesh belt (1002) is made of polytetrafluoroethylene glass fiber materials.
8. A method for recovering perfluorooctanoic acid from polytetrafluoroethylene dispersion as defined in any one of claims 1 to 7, comprising the steps of:
A. feeding material
Using polytetrafluoroethylene dispersion resin particle wet materials as raw materials, and uniformly distributing initial materials on a conveying mesh belt (1002) of a system feeding section (12) by using a feeding conveying device (11);
B. in situ concentration
The raw materials supplied in the step A are conveyed into a concentrating device (1) through a conveying mesh belt (1002), the raw materials travel for 5-20min in the concentrating device (1), and are subjected to the action of microwaves for 5-20min, water in the raw materials is vaporized into steam, the steam naturally overflows from a steam discharge port (104), and perfluoro caprylic acid is concentrated on the surface of the materials in situ to obtain concentrated materials, namely materials I;
C. Microwave and superheated steam combined gasification
B, inputting the concentrated material I in the step B into a gasification device (2) through a conveying mesh belt (1002), enabling the material I to move for 10-25min in the gasification device (2), heating the material I to 195-240 ℃ under the action of microwaves and high-temperature superheated steam for 10-25min, enabling the completely vaporized perfluoro caprylic acid and water vapor to be discharged through a mesh plate I (204), an air outlet cover (3) and an air outlet (4) in sequence under the action of a circulating fan (703);
after the perfluoro caprylic acid and water in the material I are vaporized, the remained polytetrafluoroethylene dispersion resin particles are conveyed to a system discharging section (13) through a conveying mesh belt (1002) and then flow into a third storage tank (14) for other purposes;
D. condensation
The gaseous perfluoro caprylic acid and the water vapor discharged from the step C are conveyed to a condensing device (701) under the traction action of a circulating fan (703), the gaseous perfluoro caprylic acid is cooled to 120-160 ℃ in the condensing device (701), the gaseous perfluoro caprylic acid is converted into liquid perfluoro caprylic acid, the liquid perfluoro caprylic acid is attached in the condensing device (701), and finally flows into a first storage tank (8), and the perfluoro caprylic acid product is obtained after collection and fractionation; while a small amount of condensed perfluorooctanoic acid is discharged in the form of a liquid mist with water vapor through a delivery pipe (705);
E. Liquid mist trapping
The liquid-state vaporous perfluorooctanoic acid and the water vapor discharged from the step D are conveyed to a trapping device (702) through a conveying pipe (705), the liquid-state vaporous perfluorooctanoic acid is trapped in the trapping device (702), and the liquid-state vaporous perfluorooctanoic acid is collected by a second storage tank (9) and fractionated to obtain a perfluorooctanoic acid product and clean water vapor; clean water vapor is discharged through a delivery tube (705);
F. steam heating and circulation
And E, conveying the clean steam discharged in the step E to a superheated steam heating furnace (704) through a conveying pipe (705), heating, converting the clean steam into high-temperature superheated steam, conveying the high-temperature superheated steam to an air inlet (6) through the conveying pipe (705), and sequentially passing through an air inlet cover (5), a mesh plate II (205) and a conveying mesh belt (1002), and diffusing into a material I to heat the material I by the high-temperature superheated steam.
9. The method for recovering perfluorooctanoic acid according to claim 8, wherein: the raw material is polytetrafluoroethylene dispersion resin particles with the water content of 40-60 percent.
10. The method for recovering perfluorooctanoic acid according to claim 8, wherein: the recovery rate of the perfluorooctanoic acid is more than 95%, the concentration of the perfluorooctanoic acid reaches 95-99%, the recovery period of the system is 20-50min, wherein in the step B, 91-96% of water in the raw material is vaporized into water vapor, the temperature of the raw material and the perfluorooctanoic acid contained in the raw material is less than or equal to 100 ℃, and the concentration of the perfluorooctanoic acid is improved by 11-25 times after in-situ concentration; in the step D, the recovery rate of the perfluorooctanoic acid accounts for 80-95% of the total recovery rate, and the rest part is recovered by the step E; the steam heating and circulating process in the step F is adopted, so that the energy is saved by 80-90%.
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Citations (8)
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| CN108250065A (en) * | 2016-12-28 | 2018-07-06 | 中昊晨光化工研究院有限公司 | It is a kind of that the device and method that perfluoro caprylic acid is recycled in tail gas is dried from fluoropolymer |
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| CN1662451A (en) * | 2002-06-19 | 2005-08-31 | 笹仓机械工程有限公司 | Method for recovering fluorine-containing emulsifier |
| CN1465612A (en) * | 2002-07-03 | 2004-01-07 | 中昊晨光化工研究院 | Method for recovering perfluoro caprylic acid from waste liquid of producing teflon resin |
| EP1873171A1 (en) * | 2006-06-20 | 2008-01-02 | Daikin Industries, Ltd. | Method of concentrating fluoropolymer and fluorine-containing emulsifiers |
| CN1935770A (en) * | 2006-10-17 | 2007-03-28 | 山东东岳高分子材料有限公司 | Method for recovering and treating perfluoro ammonium caprylate for PTFE resin production by dispersion method |
| JP2008268111A (en) * | 2007-04-24 | 2008-11-06 | Asahi Glass Co Ltd | Fluorine-containing carboxylic acid, fluorine-containing sulfonic acid and collecting method of derivatives thereof |
| CN103406009A (en) * | 2013-08-01 | 2013-11-27 | 中国科学院过程工程研究所 | Method and device for recovering perfluoro caprylic acid from tail gas produced in fluoropolymer production |
| CN108250065A (en) * | 2016-12-28 | 2018-07-06 | 中昊晨光化工研究院有限公司 | It is a kind of that the device and method that perfluoro caprylic acid is recycled in tail gas is dried from fluoropolymer |
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