Leacher and its application, device and method for recycling and utilizing waste plastic containing PVC

Abstract

The present application relates to waste plastic recycling technical field, specifically relates to a kind of leaching device and application thereof, a kind of device and method for recycling and utilizing PVC-containing waste plastic.The leaching device provided by the present application includes dissolving washing part and drying part, realizes the integration design of dissolving, washing and drying function, can complete multiple functions simultaneously;Combined with screw propeller, the sufficient contact and dissolution of dissolving solvent and the material to be leached are realized, the residence time and dissolution efficiency of the material to be leached are considered, that is, the residence time is effectively reduced, and the dissolution efficiency is improved;The leaching device provided by the present application is used for recycling and utilizing PVC-containing waste plastic, the continuous leaching of PVC-containing waste plastic can be realized, the corrosion intensity of downstream equipment is significantly reduced while improving the adaptability of raw materials.

Description

Technical Field

[0001] This invention relates to the field of waste plastic recycling technology, specifically to a leachator and its application, and a device and method for recycling PVC-containing waste plastics. Background Technology

[0002] Recycling waste plastics and turning them into raw materials for the production of oil and chemical products solves the problem of large amounts of unmanageable waste.

[0003] The composition of waste plastics is generally quite complex. For example, in the large quantities of PVC products found in waste plastics, chlorine can corrode processing equipment used in subsequent waste plastic reprocessing, increasing equipment investment and safety risks. Removing some of the harmful components from waste plastics before further processing them into oils or chemicals is an effective way to solve these problems.

[0004] CN1430640A discloses a method for recycling plastics. This method includes: contacting PVC with a solvent capable of dissolving it; precipitating the plastic dissolved in the solvent using a non-solvent in the presence of a phase-separating agent; wherein the phase-separating agent is miscible with the solvent but immiscible with the non-solvent, and is also present when the plastic is in contact with the solvent, thus improving the solvent's solubility of the plastic. This method is used for centralized recycling of pre-removed plastic components. It requires pre-sorting PVC products and excluding other types of plastics. For complex waste plastic systems, large amounts of plastic are mixed with large amounts of solvent, requiring sufficient mixing efficiency to completely dissolve the pre-removed components. Multi-layer stirred tanks are a good choice. However, waste plastics are generally thin and light, easily floating on the surface of the solvent. To completely dissolve the waste plastics, the entire tank needs to simultaneously possess strong axial circulation and shear force. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of existing technologies for recycling PVC-containing waste plastics, such as the need to first remove PVC products, low PVC dissolution efficiency, large PVC solvent consumption, inability to handle waste plastics with complex compositions, and complex process flow. This invention provides a leachator and its application, as well as a device and method for recycling PVC-containing waste plastics. This leachator can achieve continuous leaching of PVC-containing waste plastics and has strong raw material adaptability. It integrates dissolution, washing, and drying, performing multiple functions simultaneously. Furthermore, by recycling PVC-containing waste plastics in the leachator provided by this invention, continuous recycling of PVC-containing waste plastics is achieved, and PVC dissolution efficiency is improved.

[0006] To achieve the above objectives, a first aspect of the present invention provides an extractor comprising: a spiral propeller, a dissolving and washing section and a drying section communicating with each other, wherein the spiral propeller comprises a motor, at least one connecting rod and a propulsion blade, the connecting rod connecting the motor and the dissolving and washing section, and the propulsion blade being disposed inside the dissolving and washing section;

[0007] The dissolving and washing section includes a dissolving zone and a washing zone that communicate with each other. The dissolving zone is used to contact the dissolving solvent and the substance to be extracted and dissolve them to obtain a dissolving solution and a dissolving product. The washing zone is used to contact the dissolving product and the washing solvent and wash them to obtain a washing solution and a washing product.

[0008] The drying section is used to contact the washing product and the drying gas and dry them to obtain a gaseous product and an extract product.

[0009] The motor drives the connecting rod to rotate the propulsion blades, which in turn propels the material to be extracted downstream toward the dissolving zone, washing zone, and drying section.

[0010] The second aspect of this invention provides an application of the leaching device provided in the first aspect in the recycling of PVC-containing waste plastics and the extraction of traditional Chinese medicine.

[0011] A third aspect of the present invention provides an apparatus for recycling PVC waste plastics, the apparatus comprising: an extractor, a PVC solvent recovery unit, a PVC separator, and a PVC granulator connected in sequence;

[0012] The leaching device is the leaching device provided in the first aspect, used to contact and dissolve PVC-containing waste plastic and PVC solvent in a dissolution zone to obtain a PVC-containing solution and a dissolution product; and to contact and wash the dissolved product and washing solvent in a washing zone to obtain a PVC-containing washing solution and a washing product; and to contact and dry the washing product and drying gas in a drying section to obtain dePVC-removed waste plastic.

[0013] The PVC solvent recovery unit is connected to the dissolution outlet and the washing liquid outlet of the leaching unit, respectively, and is used to back-extract the PVC-containing solution with the back-extraction agent to obtain a mixture containing PVC solids. The PVC-containing solution is a mixture of PVC-containing dissolution solution and PVC-containing washing liquid.

[0014] The PVC separator is used to separate the mixture containing PVC solids to obtain PVC solids and PVC solvent recovery liquid;

[0015] The PVC granulator is used to granulate the PVC solid to obtain PVC granules.

[0016] A fourth aspect of the present invention provides a method for recycling PVC-containing waste plastics, the method comprising the following steps:

[0017] (1) In the leaching apparatus provided in the first aspect, PVC-containing waste plastic, which is to be leached, is introduced into the dissolution zone and is contacted with PVC solvent, which is introduced into the dissolution zone as a dissolving solvent, and is dissolved to obtain PVC-containing dissolving liquid and dissolution product; the dissolution product enters the washing zone under the action of the propulsion blades, and is contacted with the washing solvent and washed to obtain PVC-containing washing liquid and washing product; the washing product enters the drying section under the action of the propulsion blades, and is contacted with the drying gas and dried to obtain gaseous product and dePVC-removed waste plastic;

[0018] (2) The PVC-containing solution is back-extracted with a back-extracting agent, and the resulting mixture of PVC-containing solids is separated to obtain PVC solids and PVC solvent recovery liquid, wherein the PVC-containing solution is a mixture of PVC-containing dissolving liquid and PVC-containing washing liquid;

[0019] (3) Granulate the PVC solid to obtain PVC granules.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The leaching device provided by the present invention includes a dissolving and washing section and a drying section, realizing the integrated design of dissolving, washing and drying functions, and can complete multiple functions at the same time; combined with the screw propeller, it realizes the full contact and dissolution of the dissolving solvent and the leaching material, optimizes the amount of dissolving solvent used, and takes into account the residence time and dissolution efficiency of the leaching material, that is, effectively reduces the residence time and improves the dissolution efficiency.

[0022] (2) The leaching device provided by the present invention can be used for the recycling of PVC-containing waste plastics, which can realize the continuous leaching of PVC-containing waste plastics, improve the adaptability of raw materials, and significantly reduce the corrosion intensity of downstream equipment.

[0023] (3) The device for recycling PVC-containing waste plastics provided by the present invention simplifies the process flow, reduces operating costs, and facilitates industrial production design; in particular, it directly dissolves PVC-containing waste plastics in the leaching device provided by the present invention, fully removes PVC from the waste plastics, effectively improves the PVC dissolution efficiency of the waste plastics, that is, the PVC dissolution efficiency is as high as 99.9%, and significantly reduces the corrosion degree of the remaining waste plastics (i.e., leaching products) on downstream equipment.

[0024] (4) The method for recycling PVC-containing waste plastics provided by the present invention effectively combines PVC solvent and back-extraction agent to recycle PVC in waste plastics and effectively reduce wastewater discharge; in addition, the leaching product (PVC-de-PVC waste plastics) is post-processed to obtain oil and / or chemical products. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an extractor provided by the present invention;

[0026] Figure 2 This is a schematic diagram of a device for recycling PVC waste plastics provided by the present invention.

[0027] Explanation of reference numerals in the attached figures

[0028] 1. Leaching device; 3. Product pre-processor; 4. Product reactor

[0029] 5. PVC solvent recovery unit; 6. PVC separator; 7. Oils and / or chemicals.

[0030] 8. PVC granulator; 9. PVC granules; 10. PVC solvent storage tank

[0031] 11. Feeding equipment for the material to be extracted; 12. Dissolving solution outlet; 13. Washing solvent inlet.

[0032] 14. Detergent outlet; 15. Motor; 16. Connecting rod

[0033] 17. Dissolution zone shell; 18. Heat exchange pipeline; 19. Dissolution solvent inlet.

[0034] 20. Spraying equipment; 21. Drying gas inlet; 22. Leaching product outlet.

[0035] 23. Gas distributor; 24. Drying unit outer shell; 25. Drying gas outlet.

[0036] 26. Heat exchange medium inlet; 27. Heat exchange medium outlet; 28. Solid and mechanical waste outlet.

[0037] 29. Reinforced blades; 30. Propeller blades; 31. Spray chamber outer shell.

[0038] 32. Washing area outer shell; 33. Spray surface; 34. Expanded diameter section

[0039] 35. Straight section 36. Reduced diameter section Detailed Implementation

[0040] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0041] In this invention, unless otherwise specified, the “top” of the container refers to the 0-10% position of the container from top to bottom; the “upper part” of the container refers to the 10-40% position of the container from top to bottom; the “middle part” of the container refers to the 40-60% position of the container from top to bottom; the “lower part” of the container refers to the 60-90% position of the container from top to bottom; and the “bottom” of the container refers to the 90-100% position of the container from top to bottom.

[0042] The first aspect of the present invention provides an extractor, which includes: a screw propeller, a dissolution and washing section and a drying section communicating with each other, the screw propeller including a motor, at least one connecting rod and a propulsion blade, the connecting rod connecting the motor and the dissolution and washing section, and the propulsion blade disposed inside the dissolution and washing section;

[0043] The dissolving and washing section includes a dissolving zone and a washing zone that communicate with each other. The dissolving zone is used to contact the dissolving solvent and the substance to be extracted and dissolve them to obtain a dissolving solution and a dissolving product. The washing zone is used to contact the dissolving product and the washing solvent and wash them to obtain a washing solution and a washing product.

[0044] The drying section is used to contact the washing product and the drying gas and dry them to obtain a gaseous product and an extract product.

[0045] The motor drives the connecting rod to rotate the propulsion blades, which in turn propels the material to be extracted downstream toward the dissolving zone, washing zone, and drying section.

[0046] The leaching apparatus provided by the present invention includes: a screw propeller, a dissolution and washing section, and a drying section; wherein, the dissolution and washing section has two functions: dissolution and washing. In the dissolution and washing section, after the extract to be leached comes into full contact with the dissolving solvent, the pre-removed substances in the extract dissolve in the dissolving solvent and leave the equipment through the dissolving liquid outlet. The dissolved product and the residual dissolving solution are washed by the washing solvent and then dried. In the drying section, the residual dissolving solvent is further vaporized to achieve full separation of the liquid and solid phases and obtain the leaching product.

[0047] According to the present invention, preferably, the number of connecting rods is 1-2. Preferably, the electrode simultaneously drives two connecting rods to rotate, forming a twin-screw system; that is, the motor drives the connecting rods to rotate the propulsion blades, thereby generating a driving force on the material to be extracted within the system, causing it to flow downstream.

[0048] In this invention, the residence time of the substance to be extracted in the extractor is adjusted by limiting the spacing and rotation speed parameters of the propulsion blades. Preferably, the spacing of the propulsion blades is 1-200 mm, more preferably 30-100 mm; the rotation speed is 0.1-60 rpm, more preferably 0.5-30 rpm.

[0049] According to the present invention, preferably, the interior of the dissolving and washing section is provided with a heat exchange pipeline, and the inlet and outlet of the heat exchange pipeline are respectively provided with a heat exchange medium inlet and a heat exchange medium outlet.

[0050] In some embodiments of the present invention, preferably, the temperature of the heat exchange medium inlet is 70-120°C, more preferably 70-100°C; and the temperature of the heat exchange medium outlet is 0-70°C, more preferably 50-70°C.

[0051] According to the present invention, preferably, the dissolving zone includes a dissolving zone shell, and the dissolving zone shell is provided with a dissolving solvent inlet, a material to be leached feeding device and a dissolving liquid outlet; more preferably, in the direction of material flow, the dissolving zone shell is provided with a dissolving solvent inlet, a material to be leached feeding device and a dissolving liquid outlet in sequence.

[0052] In this invention, the dissolving solvent entering through the dissolving solvent inlet comes into full contact with the material to be leached entering through the material to be leached feeding device and dissolves it in the dissolving zone of the leacher; at the same time, it moves downstream under the action of the propulsion blades.

[0053] In this invention, the dissolving liquid outlet is used to lead out the dissolving liquid generated after dissolving the dissolving solvent and the leaching material from the leaching device, thereby completing the function of removing the pre-removed components from the leaching material.

[0054] According to the present invention, preferably, the material to be leached feeding device is provided with a twin-screw feeding device; more preferably, the minimum cross-sectional diameter of the material to be leached feeding device is ≥20mm, and more preferably 30-300mm.

[0055] According to the present invention, preferably, the washing area includes a washing area shell, and a spray chamber shell is disposed on the washing area shell; more preferably, a spraying device and a washing solvent inlet connected to the spraying device are disposed inside the spray chamber shell. The spraying device enables the washing solvent to be evenly distributed across the spatial cross-section inside the spray chamber shell.

[0056] According to the present invention, preferably, the inner diameter of the dissolving and washing section is 0.05-2m, for example, 0.05m, 0.1m, 0.2m, 0.3m, 0.4m, 0.5m, 1m, 1.5m, 2m, or any value within the range of any two values, preferably 0.1-0.5m; the length is 1-5m, for example, 1m, 2m, 3m, 4m, 5m, or any value within the range of any two values, preferably 2-4m. Wherein, the inner diameter refers to the diameter of the internal cavity of the dissolving and washing section.

[0057] According to the present invention, preferably, the length ratio of the dissolving zone to the washing zone is 0.25-5:1, for example, 0.25:1, 0.5:1, 0.8:1, 1:1, 2:1, 3:1, 5:1, and any value within the range of any two values, preferably 0.5-1.5:1, more preferably 0.5-1:1. In the present invention, the integrated design of the dissolving zone and the washing zone avoids frequent entry and exit of liquid and / or solid substances into and out of the equipment, and avoids blockage of solid materials in pipes and at diameter changes.

[0058] According to the present invention, preferably, the overlapping area of ​​the washing zone shell and the spray chamber shell is a spray surface, and the spray surface is provided with holes; more preferably, the diameter is 1nm-30mm, more preferably 1nm-15mm; the porosity is 40-80%, more preferably 50-70%. In the present invention, the spray surface is provided so that the washing solvent enters the washing zone through the spray surface.

[0059] According to the present invention, preferably, the area ratio of the spray surface to the outer shell of the washing zone is 0.1-0.5:1; for example, 0.1:1, 0.3:1, 0.4:1, 0.5:1, 1:1, and any value within the range of any two values, preferably 0.3-0.5:1. The spray surface covers as much as possible the upper area of ​​the outer shell of the washing zone, so that the washing liquid thoroughly cleans the material.

[0060] According to the present invention, preferably, the dissolving liquid outlet and the washing liquid outlet are each independently provided with at least one layer of filter screen. This arrangement can trap the discharged solid substances. The number of filter screen layers is 2-5, preferably 2-3 layers.

[0061] According to the present invention, preferably, the pore size of the filter screen is ≤0.1m, and more preferably 0.002-0.01m.

[0062] According to the present invention, preferably, the drying section includes a drying section shell; more preferably, the drying section shell is divided into an expanding section, a straight section and a reducing section from top to bottom.

[0063] According to the present invention, preferably, the washing area communicates with the upper middle part of the straight section.

[0064] According to the present invention, preferably, the reduced diameter section is provided with a dry gas inlet and a solid impurity outlet.

[0065] According to the present invention, preferably, a gas distributor is provided at the bottom of the straight section for distributing dry gas; more preferably, an extraction product outlet is provided at the top of the straight section.

[0066] According to the present invention, preferably, a dry gas outlet is provided at the top of the expansion section. Preferably, a cyclone separator or filter is provided inside the expansion section for gas-solid separation.

[0067] According to the present invention, preferably, the gas distributor is provided with a circular through hole, and the gas distributor and the solid waste outlet are connected through the circular through hole. Preferably, a screw pump, hose pump, or other conveying device is provided between the solid waste treatment and the circular through hole.

[0068] According to the present invention, preferably, the inside of the straight section is provided with reinforcing blades, which are used to ensure sufficient contact between the washing product and the drying gas and to dry it; more preferably, the spacing between the reinforcing blades is 5-300 mm, preferably 10-50 mm; the rotation speed is 0.1-20 rpm, preferably 1-10 rpm.

[0069] According to the present invention, preferably, the ratio of the diameter of the reinforced blade to the diameter of the straight section is 0.3-0.8:1, for example, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, and any value within the range of any two values, preferably 0.4-0.7:1.

[0070] In this invention, the washing product enters the drying section and is deposited into the straight section of the drying section under the action of gravity. The drying gas enters the drying section through the drying gas inlet, is evenly distributed by the gas distributor, and then contacts the washing product for drying. The resulting gaseous product is discharged through the drying gas outlet, and the leaching product is drawn out through the leaching product outlet.

[0071] A schematic diagram of the structure of an extractor provided by the present invention is shown below. Figure 1 As shown, by Figure 1It is understood that the leaching device includes: a screw propeller, a communicating dissolution and washing section, and a drying section. The screw propeller includes a motor 15, two connecting rods 16, and a propulsion blade 30. The connecting rods 16 connect the motor 15 and the dissolution and washing section, and the propulsion blade 30 is disposed inside the dissolution and washing section. The dissolution and washing section includes a communicating dissolution zone and a washing zone. The dissolution zone is used to contact the dissolving solvent and the material to be leached and dissolve them to obtain a dissolution liquid and a dissolution product. The washing zone is used to contact the dissolution product and the washing solvent and wash them to obtain a washing liquid and a washing product. The drying section is used to contact the washing product and the drying gas and dry them to obtain a gaseous product and an leaching product. The motor 15 drives the connecting rods 16 to rotate the propulsion blade 30, pushing the material to be leached towards the downstream dissolution zone, washing zone, and drying section.

[0072] The dissolving and washing section includes a heat exchange pipeline 18, with a heat exchange medium inlet 26 and a heat exchange medium outlet 27 at its inlet and outlet, respectively. The dissolving zone includes a dissolving zone shell 17, on which a dissolving solvent inlet 19, a material feeder 11, and a dissolving liquid outlet 12 are sequentially arranged, following the material flow. The washing zone includes a washing zone shell 32, on which a spray chamber shell 31 is arranged. Inside the spray chamber shell 31 is a spraying device 20 and a washing solvent inlet 13 connected to the spraying device 20. The overlapping area of ​​the washing zone shell 31 and the spray chamber shell 32 forms a spray surface 33, which is perforated. The dissolving liquid outlet... At least one filter screen is independently provided for outlets 12 and 13; the drying section includes a drying section shell 24; the drying section shell 24 is divided into an expanding section 34, a straight section 35 and a narrowing section 36 from top to bottom, and the washing area is connected to the upper middle part of the straight section 35; the narrowing section 36 is provided with a drying gas inlet 21 and a solid impurity outlet 28; a gas distributor 23 is provided at the bottom of the straight section 35; an extraction product outlet 22 is provided at the top of the straight section 35, and a drying gas outlet 25 is provided at the top of the expanding section 34; a circular through hole is provided on the gas distributor 23, and the gas distributor 23 and the solid impurity outlet 28 are connected through the circular through hole; reinforcing blades 29 are provided inside the straight section 35.

[0073] According to a particularly preferred embodiment of the present invention, the immersion apparatus includes: a screw propeller, a dissolution and washing section and a drying section communicating with each other, the screw propeller including a motor, at least one connecting rod and a propulsion blade, the connecting rod connecting the motor and the dissolution and washing section, and the propulsion blade disposed inside the dissolution and washing section;

[0074] The dissolving and washing section includes a dissolving zone and a washing zone that communicate with each other. The dissolving zone is used to contact the dissolving solvent and the substance to be extracted and dissolve them to obtain a dissolving solution and a dissolving product. The washing zone is used to contact the dissolving product and the washing solvent and wash them to obtain a washing solution and a washing product.

[0075] The drying section is used to contact the washing product and the drying gas and dry them to obtain a gaseous product and an extract product.

[0076] The motor drives the connecting rod to rotate the propulsion blades, pushing the material to be extracted towards the downstream dissolution zone, washing zone and drying section;

[0077] The spacing between the propulsion blades is 30-100mm; the rotational speed is 0.5-30mm.

[0078] The inner diameter of the dissolving and washing section is 0.1-0.5m; the length is 2-4m; and the length ratio of the dissolving zone to the washing zone is 0.5-1.5:1.

[0079] The second aspect of this invention provides an application of the leaching device provided in the first aspect in the extraction of PVC-containing waste plastics and traditional Chinese medicine.

[0080] Preferably, the leaching device provided by the present invention is used in the recycling of PVC-containing waste plastics.

[0081] A third aspect of the present invention provides an apparatus for recycling PVC waste plastics, the apparatus comprising: an extractor, a PVC solvent recovery unit, a PVC separator, and a PVC granulator connected in sequence;

[0082] The leaching device is the leaching device provided in the first aspect, used to contact and dissolve PVC-containing waste plastic and PVC solvent in a dissolution zone to obtain a PVC-containing solution and a dissolution product; and to contact and wash the dissolved product and washing solvent in a washing zone to obtain a PVC-containing washing solution and a washing product; and to contact and dry the washing product and drying gas in a drying section to obtain dePVC-removed waste plastic.

[0083] The PVC solvent recovery unit is connected to the dissolution outlet and the washing liquid outlet of the leaching unit, respectively, and is used to back-extract the PVC-containing solution with the back-extraction agent to obtain a mixture containing PVC solids. The PVC-containing solution is a mixture of PVC-containing dissolution solution and PVC-containing washing liquid.

[0084] The PVC separator is used to separate the mixture containing PVC solids to obtain PVC solids and PVC solvent recovery liquid;

[0085] The PVC granulator is used to granulate the PVC solid to obtain PVC granules.

[0086] In this invention, unless otherwise specified, the leaching product refers to dePVC waste plastic.

[0087] According to the present invention, preferably, the PVC solvent recovery liquid outlet of the PVC separator is connected to the dissolving solvent inlet of the leaching device, for returning the PVC solvent recovery liquid to the leaching device. This arrangement aims to improve the utilization rate of PVC solvent while reducing waste liquid discharge.

[0088] According to the present invention, preferably, the apparatus further includes: a PVC solvent storage tank connecting the PVC separator and the leaching device, for storing the PVC solvent recovery liquid.

[0089] According to the present invention, preferably, the apparatus further includes: a product preprocessor and a product reactor; more preferably, the product processor is connected to the leaching product outlet of the preprocessor and is used to thermally dissolve the dePVC waste plastic to obtain a liquid phase mixture; more preferably, the product reactor is connected to the outlet of the product preprocessor and is used to thermally crack the liquid phase mixture to obtain oil and / or chemical products.

[0090] This invention provides a device for recycling PVC-containing waste plastics, such as... Figure 2 As shown, the device includes: an extractor 1, a PVC solvent recovery unit 5, a PVC separator 6, and a PVC granulator 8 connected in sequence; wherein, the extractor 1 is used to contact and dissolve PVC-containing waste plastic and PVC solvent in the dissolution zone to obtain a PVC-containing solution and a dissolution product; and to contact and wash the dissolved product and washing solvent in the washing zone to obtain a PVC-containing washing solution and a washing product; and to contact and dry the washing product and drying gas in the drying section to obtain dePVC-removed waste plastic;

[0091] The PVC solvent recovery unit 5 is connected to the solvent outlet 12 and the washing liquid outlet 14 of the leaching unit 1, respectively, and is used to back-extract the mixture containing PVC solvent and PVC washing liquid with the back-extraction agent to obtain a mixture containing PVC solids; the PVC separator 6 is used to separate the mixture containing PVC solids to obtain PVC solids and PVC solvent recovery liquid; the PVC granulator 8 is used to granulate the PVC solids to obtain PVC granules 9.

[0092] The PVC solvent recovery liquid outlet of the PVC separator 6 is connected to the dissolving solvent inlet of the leaching device 1, which is used to return the PVC solvent recovery liquid to the leaching device 1; the device also includes: a PVC solvent storage tank 10 connecting the PVC separator 6 and the leaching device 1, which is used to store the PVC solvent recovery liquid.

[0093] The device also includes a product preprocessor 3 and a product reactor 4. The product preprocessor 3 is connected to the leaching product outlet of the leaching extractor 1 and is used to thermally dissolve the dePVC waste plastic to obtain a liquid phase mixture. The product reactor 4 is connected to the outlet of the product preprocessor 3 and is used to thermally crack the liquid phase mixture to obtain oil and / or chemical products 7.

[0094] A fourth aspect of this invention provides a method for recycling PVC-containing waste plastics, the method comprising the following steps:

[0095] (1) In the leaching apparatus provided in the first aspect, PVC-containing waste plastic, which is to be leached, is introduced into the dissolution zone and is contacted with PVC solvent, which is introduced into the dissolution zone as a dissolving solvent, and is dissolved to obtain PVC-containing dissolving liquid and dissolution product; the dissolution product enters the washing zone under the action of the propulsion blades, and is contacted with the washing solvent and washed to obtain PVC-containing washing liquid and washing product; the washing product enters the drying section under the action of the propulsion blades, and is contacted with the drying gas and dried to obtain gaseous product and dePVC-removed waste plastic;

[0096] (2) The PVC-containing solution is back-extracted with a back-extracting agent, and the resulting mixture of PVC-containing solids is separated to obtain PVC solids and PVC solvent recovery liquid, wherein the PVC-containing solution is a mixture of PVC-containing dissolving liquid and PVC-containing washing liquid;

[0097] (3) Granulate the PVC solid to obtain PVC granules.

[0098] In this invention, the selection range for the PVC-containing waste plastics is relatively wide, as long as the waste plastics contain PVC. Preferably, based on the weight of the PVC-containing waste plastics, the PVC content is 1-99 wt%, more preferably 1-50 wt%, and even more preferably 1-20 wt%. The PVC content is calculated by measuring the chlorine content using ICP.

[0099] In this invention, the PVC solvent is intended to dissolve PVC in waste plastics. Preferably, the PVC solvent is selected from at least one of aromatic compounds, ketones, halogenated alkanes, and heterocyclic compounds; more preferably, the aromatic compounds are selected from at least one of benzene, toluene, and xylene, and the ketones are selected from C1-C6 alkyl ketones and / or C3-C6 alkyl ketones. 10 The cycloalkyl ketone, for example, butanone and / or cyclohexanone, wherein the halogenated alkane is selected from at least one of methyl chloride, ethane chloride and methyl bromide; the heterocyclic compound includes, but is not limited to, furan, imidazole, pyrimidine, pyridine, etc.

[0100] In this invention, the dissolution conditions have a wide range of selection. Preferably, the dissolution conditions include: a temperature of 25-100℃, more preferably 40-90℃, and even more preferably 60-80℃; and a time of ≥5 min, preferably 10-30 min. Using these preferred conditions is more conducive to ensuring the dissolution efficiency of PVC and reducing energy consumption.

[0101] In some embodiments of the present invention, preferably, the mass hourly space velocity ratio of the PVC solvent to the PVC-containing waste plastic is 1-100:1, for example, 1:1, 1:2, 1:5, 1:8, 1:10, 1:20, 1:50, 1:80, 1:100, and any value within the range of any two values, preferably 1-10:1.

[0102] In some embodiments of the present invention, preferably, the temperature of the drying gas is 60-100°C, more preferably 70-90°C; and the linear velocity is 0.1-1 m / s, more preferably 0.1-0.5 m / s. In the present invention, the drying gas includes, but is not limited to, inert gases, such as nitrogen.

[0103] In this invention, a wide range of stripping agents can be selected, as long as the PVC in the PVC solution is insoluble in the stripping agent while the PVC solvent is soluble in the stripping agent. Preferably, the stripping agent is selected from at least one of water, alcohol, and alkanes, with water being the most preferred. The type and properties of the water are not limited.

[0104] In some embodiments of the present invention, preferably, the back-extraction conditions include: a temperature of 100-150°C, more preferably 50-80°C; and a time of 0.1-24 h, more preferably 0.2-2 h. Using these preferred conditions is more conducive to recovering PVC solids from the PVC solution, thereby increasing the yield of PVC solids.

[0105] In some embodiments of the present invention, preferably, the granulation conditions include: a temperature of 50-150°C, more preferably 50-100°C; and a time of 0.1-24 h, more preferably 0.2-2 h. Using these preferred conditions is more conducive to achieving the recycling of waste plastics with lower energy consumption.

[0106] According to the present invention, preferably, the method further includes: returning the PVC solvent recovery liquid and mixing it with the PVC solvent; more preferably, the PVC solvent recovery liquid is stored before returning the PVC solvent recovery liquid and mixing it with the PVC solvent.

[0107] To further improve the recycling of waste plastics, the remaining waste plastics (i.e., dePVC waste plastics) undergo post-processing. Preferably, the method further includes: sequentially subjecting the dePVC waste plastics to thermal dissolution and thermal pyrolysis to obtain oils and / or chemicals.

[0108] According to the present invention, preferably, the thermal dissolution refers to thermally dissolving the dePVC waste plastic with an organic solvent to obtain a liquid mixture. The organic solvent is selected from at least one of diesel oil, naphtha, catalytic cracking cycle oil, and hydrotreated tail oil.

[0109] In this invention, the thermal dissolution is intended to pretreat the dePVC waste plastic to obtain a liquid mixture. Preferably, the conditions for thermal dissolution include: a temperature of 200-600℃, more preferably 300-500℃; a time of 0.5-3h, more preferably 0.5-1.5h; and a weight ratio of 1:5-50, more preferably 1:5-15. Here, the weight ratio refers to the weight ratio of the dePVC waste plastic to the organic solvent.

[0110] According to the present invention, preferably, the thermal cracking refers to thermally cracking the liquid phase mixture to obtain oil and / or chemical products.

[0111] In this invention, the thermal pyrolysis aims to convert the liquid mixture into a low molecular weight product, yielding oils and / or chemicals. Preferably, the thermal pyrolysis conditions include: a temperature of 300-600°C, more preferably 350-500°C; and a time of 0.1-3 hours, more preferably 0.2-2 hours.

[0112] The present invention will be described in detail below through embodiments.

[0113] In the examples and comparative examples, the chloride ion concentration in the PVC-containing solution (i.e., a mixture of PVC-containing dissolving solution and PVC-containing washing solution) was directly measured using a PEICP-OES instrument from the United States; the chloride ion concentration in PVC-containing waste plastics was measured by first dissolving the PVC-containing waste plastics, then measuring the chloride content by ICP, and finally calculating the concentration.

[0114] Waste plastics containing PVC include polyethylene, polypropylene, and PVC; of which, based on the weight of the waste plastics containing PVC, the PVC content is 5 wt%.

[0115] Calculation formula:

[0116] And / or,

[0117]

[0118] The units for chloride ion concentration in PVC-containing solutions and PVC-containing waste plastics are g / g, the units for mass of PVC-containing solutions are g, the units for mass of PVC-containing waste plastics are g, and the units for PVC content are wt%.

[0119] Example 1

[0120] (1) Immersion apparatus such as Figure 1 As shown, the extractor includes a screw propeller, a dissolving and washing section, and a drying section. The screw propeller includes a motor 15, two connecting rods 16, and a propulsion blade 30. The connecting rods 16 connect the motor 15 and the dissolving and washing section, and the propulsion blade 30 is disposed inside the dissolving and washing section. The dissolving and washing section includes a dissolving area and a washing area. The motor 15 drives the connecting rods 16 to rotate the propulsion blade 30, thereby pushing the extractant to move downstream towards the dissolving area, washing area, and drying section.

[0121] The dissolving and washing section includes a heat exchange pipeline 18 with a heat exchange medium inlet 26 and an outlet 27. The dissolving zone includes a dissolving zone shell 17, on which a dissolving solvent inlet 19, a material feeder 11, and a dissolving liquid outlet 12 are sequentially arranged, following the material flow. The washing zone includes a washing zone shell 32, on which a spray chamber shell 31 is installed. Inside the spray chamber shell 31 is a spraying device 20 and a washing solvent inlet 13 connected to the spraying device 20. The overlapping area of ​​the washing zone shell 31 and the spray chamber shell 32 forms a spray surface 33, which has holes. The dissolving liquid outlet 12 and the washing... The liquid outlet 13 is equipped with at least two layers of filter screens (pore size 0.1m); the drying section includes a drying section shell 24; the drying section shell 24 is divided into an expanding section 34, a straight section 35 and a narrowing section 36 from top to bottom, and the washing area is connected to the middle and upper part of the straight section 35; the narrowing section 36 is equipped with a drying gas inlet 21 and a solid and impurity outlet 28; a gas distributor 23 is provided at the bottom of the straight section 35; a leaching product outlet 22 is provided at the upper part of the straight section 35, and a drying gas outlet 25 is provided at the top of the expanding section 34; the gas distributor 23 is equipped with a circular through hole, and the gas distributor 23 and the solid and impurity outlet 28 are connected through the circular through hole; the interior of the straight section 35 is equipped with reinforcing blades 29.

[0122] The propulsion blades are spaced 50 mm apart and rotate at 30 rpm. The inner diameter of the dissolving and washing section is 0.3 m and the length is 2 m. The length ratio of the dissolving zone to the washing zone is 1:1.

[0123] The inlet temperature of the heat exchange medium is 100℃; the outlet temperature of the heat exchange medium is 50℃.

[0124] The diameter of the holes is 5 mm, and the porosity is 60%; the area ratio of the spray surface to the outer shell of the washing area is 0.5:1.

[0125] The spacing between the reinforced blades is 15mm, and the rotation speed is 5rpm; the ratio of the diameter of the reinforced blades to the diameter of the straight section is 0.5:1.

[0126] (2) Equipment for recycling PVC waste plastics, such as Figure 2 As shown, the device includes: the aforementioned leaching device 1, PVC solvent recovery device 5, PVC separator 6, and PVC granulator 8 connected in sequence; the device also includes: a PVC solvent storage tank 10, which is connected to the PVC separator 6 and the leaching device 1; the device also includes: a product pre-processor 3 and a product reactor 4, the product pre-processor 3 being connected to the leaching product outlet of the pre-leaching device 1, and the product reactor 4 being connected to the outlet of the product pre-processor 3.

[0127] (3) A method for recycling PVC-containing waste plastics, the method including:

[0128] a. PVC-containing waste plastic, which is to be leached, is introduced into the dissolution zone and then contacted with methyl ethyl ketone (MEK), which is introduced into the dissolution zone as a solvent, to dissolve it (temperature: 60℃, time: 30min; mass hourly space velocity of MEK to PVC-containing waste plastic: 10:1), to obtain a PVC-containing solution and a dissolution product. The dissolution product enters the washing zone under the action of the propulsion blades, contacts the washing solvent, and is washed to obtain a PVC-containing washing solution and a washing product. The washing product enters the drying section under the action of the propulsion blades, contacts the drying gas (nitrogen, temperature: 85℃, linear velocity: 0.2m / s), and is dried to obtain a gaseous product and dePVC-removed waste plastic.

[0129] b. The PVC-containing solution (a mixture of PVC-containing solvent and PVC-containing washing liquid) is back-extracted with water. The back-extraction conditions include a temperature of 70°C and a time of 0.5 h. The resulting mixture containing PVC solids is then separated to obtain PVC solids and PVC solvent recovery liquid. The PVC solvent recovery liquid is then returned and mixed into the PVC solvent.

[0130] c. Granulate the solid PVC. The granulation conditions include: temperature of 80℃ and time of 1 hour to obtain PVC granules.

[0131] d. Mix the dePVC waste plastic with diesel oil at a weight ratio of 1:10, then heat-dissolve at 300℃ for 0.5h, and then thermally crack the resulting liquid mixture at 450℃ for 1h to obtain oil products and / or chemical products.

[0132] The PVC dissolution efficiency is 99.9%.

[0133] Example 2

[0134] According to Example 1, the difference is that the setting of the extractor is different, that is, the rotation speed of the propulsion blade 30 is replaced with 60 rpm.

[0135] The PVC-containing waste plastic is recycled according to the apparatus and method for recycling PVC-containing waste plastic in Example 1.

[0136] The PVC dissolution efficiency is 95.6%.

[0137] Example 3

[0138] According to Example 1, the difference is that the setting of the extractor is different, that is, the length ratio of the dissolving zone to the washing zone is replaced with 0.4:1.

[0139] The PVC-containing waste plastic is recycled according to the apparatus and method for recycling PVC-containing waste plastic in Example 1.

[0140] The PVC dissolution efficiency is 97.2%.

[0141] Example 4

[0142] According to Example 1, the difference is that the setting of the extractor is different, that is, the number of connecting rods is one.

[0143] The PVC-containing waste plastic is recycled according to the apparatus and method for recycling PVC-containing waste plastic in Example 1.

[0144] The PVC dissolution efficiency is 98.1%.

[0145] Example 5

[0146] According to Example 1, the difference is that the setting of the extractor is different, that is, the spacing of the propulsion blades 30 is replaced with 150 rpm.

[0147] The PVC-containing waste plastic is recycled according to the apparatus and method for recycling PVC-containing waste plastic in Example 1.

[0148] The PVC dissolution efficiency is 95.8%.

[0149] Comparative Example 1

[0150] A stirred tank reactor was used as the PVC leaching vessel. The height-to-diameter ratio of the stirred tank was 1.5:1. Waste PVC and methyl ethyl ketone (MEK) were added to the stirred tank in a single batch, with a total volume of 8L. The mass ratio of the waste PVC to MEK was 1:10. The stirred tank used a single-layer, six-bladed impeller with a blade diameter ratio of 2:5 to the tank diameter. The ratio of the impeller height from the bottom to the total height of the mixed fluid was 1:3, and the impeller rotation speed was 30 rpm. The waste plastic inlet was located at the top of the reactor, with an addition rate of 50 g / min. MEK entered the stirred tank through a side inlet at an addition rate of 200 g / min.

[0151] After the experiment, the PVC dissolution efficiency was calculated to be 90.3%.

[0152] A comparison of the results from the proportions and examples shows that, compared with conventional continuous batch reactors, the leaching device provided by this invention overcomes the problem of low dissolution efficiency of waste plastics due to varying material residence times, thus achieving higher PVC dissolution efficiency and being suitable for continuous material production. In particular, by adjusting parameters such as the rotational speed / spacing of the propulsion blades, the number of connecting rods, and the length ratio of the dissolution zone to the washing zone in the leaching device, the PVC dissolution efficiency of PVC-containing waste plastics is further improved.

[0153] Meanwhile, the method for recycling PVC-containing waste plastics provided by this invention achieves a PVC particle recovery rate of up to 99.9% in waste plastics, reducing the possibility of catalyst deactivation in subsequent processes and the corrosiveness of leaching products to equipment, and avoiding the treatment of alkaline slag generated from PVC processing.

[0154] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for recycling PVC-containing waste plastics, characterized in that, The method includes the following steps: (1) In the leaching device, PVC-containing waste plastic, which is to be leached, is introduced into the dissolution zone and is contacted with PVC solvent, which is introduced into the dissolution zone as a dissolving solvent, and dissolved to obtain PVC-containing solution and dissolution product; the dissolution product enters the washing zone under the action of the propulsion blades, contacts the washing solvent and is washed to obtain PVC-containing washing liquid and washing product; the washing product enters the drying section under the action of the propulsion blades, contacts the drying gas and is dried to obtain gas product and dePVC-removed waste plastic; (2) the PVC-containing solution is back-extracted with the back-extracting agent, and the resulting mixture of PVC-containing solids is separated to obtain PVC solids and PVC solvent recovery liquid, wherein the PVC-containing solution is a mixture of PVC-containing solution and PVC-containing washing liquid; (3) the PVC solids are granulated to obtain PVC particles; The dissolution temperature is 40-90℃, and the time is 5-30 minutes. The extractor includes a screw propeller, a dissolving and washing section, and a drying section. The screw propeller includes a motor, at least one connecting rod, and propulsion blades. The connecting rod connects the motor and the dissolving and washing section. The propulsion blades are disposed inside the dissolving and washing section. The spacing between the propulsion blades is 30-100 mm, and the rotation speed is 0.5-30 rpm. The dissolving and washing section includes a dissolving zone and a washing zone that communicate with each other. The dissolving zone is used to contact and dissolve the dissolving solvent and the substance to be leached to obtain a dissolving solution and a dissolving product. The washing zone is used to contact and wash the dissolving product and the washing solvent to obtain a washing solution and a washing product. The length ratio of the dissolving zone to the washing zone is 0.5-1.5:

1. The inner diameter of the dissolving and washing section is 0.1-0.5 m, and the length is 2-4 m. The dissolving zone includes a dissolving zone shell, which is provided with a dissolving solvent inlet, a substance to be leached feeding device, and a dissolving solution outlet. The dissolving solution outlet and the washing solution outlet are each independently provided with at least one layer of filter screen. The drying section is used to contact the washing product and the drying gas and dry them to obtain a gaseous product and an extract product. The motor drives the connecting rod to rotate the propulsion blades, which in turn propels the material to be extracted downstream toward the dissolving zone, washing zone, and drying section.

2. The method according to claim 1, wherein, The number of connecting rods is 1-2; And / or, the interior of the dissolving and washing section is provided with heat exchange pipelines, and the inlet and outlet of the heat exchange pipelines are respectively provided with heat exchange medium inlet and heat exchange medium outlet; The temperature of the heat exchange medium inlet is 70-120℃; the temperature of the heat exchange medium outlet is 0-70℃.

3. The method according to claim 2, wherein, The temperature at the inlet of the heat exchange medium is 70-100℃; the temperature at the outlet of the heat exchange medium is 50-70℃.

4. The method according to claim 1, wherein, The washing area includes a washing area shell, and a spray chamber shell is provided on the washing area shell; The spray chamber housing is equipped with a spraying device and a washing solvent inlet connected to the spraying device.

5. The method according to claim 4, wherein, Following the material flow, the outer shell of the dissolving zone is sequentially provided with a dissolving solvent inlet, a material to be extracted feeding device, and a dissolving liquid outlet; And / or, the overlapping area of ​​the washing area shell and the spray chamber shell is the spray surface, and the spray surface is provided with holes; The diameter of the pores is 1 nm-30 mm; the porosity is 40-80%. The area ratio of the spray surface to the outer shell of the washing area is 0.1-0.5:1; The filter screen has a pore size of ≤0.1m.

6. The method according to claim 5, wherein, The diameter of the pores is 1 nm-15 mm; the porosity is 50-70%. The area ratio of the spray surface to the outer shell of the washing area is 0.3-0.5:1; The filter screen has a pore size of 0.002-0.01 m.

7. The method according to claim 1, wherein, The drying section includes a drying section outer shell; The outer shell of the drying section is divided into an expanding section, a straight section, and a reducing section from top to bottom.

8. The method according to claim 7, wherein, The washing area is connected to the upper middle part of the straight section; And / or, the reduced diameter section is provided with a dry gas inlet and a solid impurity outlet; And / or, a gas distributor is provided at the bottom of the straight section; And / or, the upper part of the straight section is provided with a leaching product outlet; And / or, a dry gas outlet is provided at the top of the expanded section.

9. The method according to claim 8, wherein, The gas distributor is provided with a circular through hole, and the gas distributor and the solid impurity outlet are connected through the circular through hole; And / or, the interior of the straight section is provided with reinforced blades; The spacing between the reinforced blades is 5-300 mm; the rotational speed is 0.1-20 rpm. The ratio of the diameter of the reinforced blade to the diameter of the straight section is 0.3-0.8:

1.

10. The method according to claim 9, wherein, The spacing between the reinforced blades is 10-50 mm; the rotation speed is 1-10 rpm; The ratio of the diameter of the reinforced blade to the diameter of the straight section is 0.4-0.7:

1.

11. The method according to claim 1, wherein, Based on the weight of the PVC-containing waste plastic, the PVC content is 1-99 wt%; And / or, the PVC solvent is selected from at least one of aromatic compounds, ketones, halogenated alkanes and heterocyclic compounds; And / or, the dissolution temperature is 60-80℃; the time is 10-30 min; And / or, the mass hourly space velocity ratio of the PVC solvent to the PVC-containing waste plastic is 1-100:1; And / or, the back-extraction agent is selected from at least one of water, alcohol and alkanes.

12. The method according to claim 11, wherein, Based on the weight of the PVC-containing waste plastic, the PVC content is 1-50 wt%; And / or, the mass hourly space velocity ratio of the PVC solvent to the PVC-containing waste plastic is 1-10:

1.

13. The method according to claim 12, wherein, Based on the weight of the PVC-containing waste plastic, the PVC content is 1-20 wt%.

14. The method according to claim 1, wherein, The method further includes: returning the PVC solvent recovery liquid and mixing it with the PVC solvent; And / or, the PVC solvent recovery liquid is stored before being returned and mixed with the PVC solvent; And / or, the method further includes: sequentially subjecting the dePVC waste plastic to thermal dissolution and thermal pyrolysis to obtain oil and / or chemical products.

15. A device for recycling PVC waste plastics, characterized in that, The method described in any one of claims 1-14 is carried out in the apparatus, which comprises: an extractor, a PVC solvent recovery unit, a PVC separator, and a PVC granulator connected in sequence. The extractor is used to contact and dissolve PVC-containing waste plastic and PVC solvent in a dissolution zone to obtain a PVC-containing solution and a dissolution product; and to contact and wash the dissolved product and washing solvent in a washing zone to obtain a PVC-containing washing solution and a washing product; and to contact and dry the washing product and drying gas in a drying section to obtain dePVC-removed waste plastic. The PVC solvent recovery unit is connected to the dissolution outlet and the washing liquid outlet of the leaching unit, respectively, and is used to back-extract the PVC-containing solution with the back-extraction agent to obtain a mixture containing PVC solids. The PVC-containing solution is a mixture of PVC-containing dissolution solution and PVC-containing washing liquid. The PVC separator is used to separate the mixture containing PVC solids to obtain PVC solids and PVC solvent recovery liquid; The PVC granulator is used to granulate the PVC solid to obtain PVC granules.

16. The apparatus according to claim 15, wherein, The PVC solvent recovery liquid outlet of the PVC separator is connected to the dissolving solvent inlet of the leaching device, and is used to return the PVC solvent recovery liquid to the leaching device. And / or, the apparatus further includes: a PVC solvent storage tank connecting the PVC separator and the leaching device for storing the PVC solvent recovery liquid.

17. The apparatus according to claim 15 or 16, wherein, The apparatus further includes: a product preprocessor and a product reactor; And / or, the product preprocessor is connected to the leaching product outlet of the pre-leaching extractor for thermally dissolving the dePVC waste plastic to obtain a liquid phase mixture; And / or, the product reactor is connected to the outlet of the product preprocessor for thermally cracking the liquid phase mixture to obtain oil and / or chemical products.

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