Polyester cotton blended fabric recovery method and system using rotary hydrolysis reactor

Abstract

The invention discloses a method for treating polyester and cotton blended fabric waste. The method comprises the step of adding the polyester and cotton blended fabric waste into a rotary drum of a rotary hydrolysis reactor. Adding water and alkali into the rotary hydrolysis reactor and heating; polyester cotton blended fabric waste is stirred with a plurality of ribbed plates by rotating an internal drum relative to a rotating hydrolysis reactor housing, so that PET is hydrolyzed into TPA and ethylene glycol solutions and solid recycled cotton containing no PET. The TPA and ethylene glycol solutions are separated from the solid recovery cotton and directed into a hydrolysate recovery container. The TPA is precipitated and separated from the remaining liquid in a hydrolysate recovery vessel, thereby recovering ethylene glycol.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 355,140, ​​filed on June 24, 2022, which is incorporated herein by reference. Background Art

[0003] Millions of tons of fabric waste are generated every year. Much of this fabric waste ends up in landfills. Of the fabric waste sent to landfills, a large portion is blended fabrics that include cotton and synthetic polyester materials. The polyester portion of these blends can take up to 200 years to decompose in landfills. As a result, polyester-cotton blended fabric waste can have significant harmful effects on the environment, including the release of greenhouse gases and the leaching of toxins and dyes into the surrounding soil and water.

[0004] In order to reduce the impact on the environment, many methods and systems are used to recycle at least a portion of this fabric waste. Most of these methods require mechanical shredding or size reduction of the fabric waste so that the fabric can be reused as rags, stuffing and insulation. When the waste stream is a pure material such as 100% polyester fabric or 100% cotton fabric, mechanical size reduction produces the highest value products. Blended fabrics can also be mechanically reduced in size, but the value of the products applicable to these blends is much lower. Essentially, mechanical size reduction of all fabrics will degrade the fabric, and spinning with shredded fabric will result in a decrease in yarn quality. Therefore, there are limited end products that can be economically produced using mechanically shredded fabrics.

[0005] Other methods for recycling polyester-cotton blended fabric waste have also been proposed, including chemical separation of cotton from polyester (polyethylene terephthalate or PET). Some of these methods use a depolymerization reaction to dissolve the PET fibers, thereby separating the PET from the cotton fibers. Known depolymerization methods are not economically feasible when scaled up. For example, many of these methods focus on recovering the lower-value PET, while the separated cotton is degraded to a cellulose level that requires reconstruction. This method requires costly additional steps to make the cotton usable again, otherwise the cotton is destroyed. In some cases, the cotton is degraded to a cellulosic material that must be reconstructed to make a viscous fiber. In addition, the recycled PET has limited use in new products, mainly for lower-value plastic water bottles. Some of these methods produce some PET, which is used to make low-grade fibers used in some textiles. Therefore, these methods do not make the most efficient use of the separated cotton and PET.

[0006] Known depolymerization methods for separating polyester and cotton also have other disadvantages that make them unsuitable for large-scale textile recycling. For example, these methods and the equipment used in these methods require large amounts of energy, water, and chemicals to ensure effective depolymerization reactions. The energy, water, and chemical requirements alone make these methods expensive to operate. In addition, the equipment used in these methods is not easily scaled up to large-scale recycling operations.

[0007] Specifically, conventional batch reactors that can be used to implement the depolymerization process have limited loading capacity for solid textile products. These reactors are also difficult and time-consuming to load and unload, and even require cleaning of the interior after manually removing the solid material. Therefore, operating batch reactors in such applications requires a lot of labor. These types of reactors also require relatively long run times because the temperature needs to be increased to effectively separate PET and cotton. More water and a corresponding increase in chemicals are also required in such reactors, which is largely due to the type of stirring and mixing mechanism used in these machines, which is mainly a rotating stirrer or paddle. If the amount of water is not large enough, the paddle will be blocked by the fabric hanging on the paddle. This will lead to a significant increase in water, chemical and labor costs. In addition, batch reactors are difficult to clean and require a lot of time and resources to maintain. These devices result in long production downtime, high operating costs and low production speeds, so it is not economical to use these devices in large-scale textile recycling operations. Summary of the invention

[0008] In view of the above, a general object of the present invention is to provide a method and system for recycling polyester-cotton blended fabrics that can be operated at low cost and can be scaled up to large-scale production.

[0009] Another object of the present invention is to provide a method and system for recycling polyester cotton blend fabrics which requires minimal labor to operate.

[0010] Another object of the present invention is to provide a method and system for recycling polyester-cotton blended fabrics that can produce high-quality end products suitable for multiple reuses.

[0011] A related object of the present invention is to provide a method and system for recycling polyester-cotton blended fabrics, which can use the component materials used in the blended fabrics for 100% cotton products, while also providing pure terephthalic acid and ethylene glycol, both of which can be used to prepare polyester or any other plastic, or especially ethylene glycol can be used for coolants, hydraulic oils and coatings.

[0012] Another related object of the present invention is to provide a method and system for recycling polyester-cotton blended fabrics, which method and system can recycle buttons, zippers and other metal parts in garments as well as melamine buttons.

[0013] Another object of the present invention is to provide an energy efficient method and system for recycling polyester-cotton blended fabrics.

[0014] Another object of the present invention is to provide a method and system for recycling polyester cotton blend fabrics which utilizes a minimum amount of water and chemicals.

[0015] A related object of the present invention is to provide a method and system for recycling polyester-cotton blend fabrics which recovers the applied chemicals and cleaning water.

[0016] Another object of the present invention is to provide a method and system for recycling polyester-cotton blended fabrics which can be automatically loaded and unloaded quickly and easily.

[0017] Other objects and advantages of the present invention will become apparent after reading the following detailed description and referring to the accompanying drawings.The objects identified do not limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The flowchart of FIG. 1 shows exemplary steps of the method for recycling polyester-cotton blended fabric materials of the present invention.

[0019] Figure 2 The flowchart of FIG. 1 shows additional exemplary steps of the method of recycling polyester-cotton blended fabric material of the present invention.

[0020] Figure 3 is a schematic diagram of a hydrolysis and cotton recovery system illustrative of the method of recycling polyester-cotton blended fabric material of the present invention.

[0021] Figure 4 is a schematic diagram of a chemical recovery system illustrative of the method for recycling polyester-cotton blended fabric material of the present invention.

[0022] Figure 5 is a front view of an exemplary rotary hydrolysis reactor used in the polyester-cotton blended fabric recycling method of the present invention.

[0023] Figure 6 yes Figure 5 Side view of a rotating hydrolysis reactor.

[0024] Figure 7 yes Figure 5 Side view of a rotary hydrolysis reactor showing the reactor in the loading position.

[0025] Figure 8 yes Figure 5 Side view of a rotary hydrolysis reactor showing the reactor in the unloading position.

[0026] Fig. 9 yes Figure 5 Schematic diagram of a descriptive slurry heating system for a rotary hydrolysis reactor.

[0027] Fig.10 yes Figure 5 A side perspective cutaway view of a rotary hydrolysis reactor showing the reactor in an unloading position and the front door in an open position.

[0028] Fig.11 yes Figure 5 A side cutaway view of a rotary hydrolysis reactor showing the reactor in an unloading position and the front door in an open position.

[0029] Fig.12 yes Figure 5 Side view of the internal drum of a rotating hydrolysis reactor.

[0030] Fig.13 yes Fig.12 End view of the inner drum.

[0031] Fig.14 yes Fig.12 The inner roller edge Fig.12 The cross-sectional view along line 14-14 shows a rib on the inner wall of the inner drum.

[0032] Fig.15 yes Figure 5 Side view of a rotary hydrolysis reactor equipped with a hopper assembly instead of a front door and showing the hopper in a lowered position.

[0033] Fig.16 yes Fig. 9 Side view of a rotary hydrolysis reactor showing the front hopper in the raised position. DETAILED DESCRIPTION

[0034] See attached Figure 1-4, which provides a schematic diagram of an exemplary method and system for recycling polyethylene terephthalate (PET)-cotton blended fabric materials in particular. This material is commonly referred to as polyester-cotton blended fabrics, sometimes also referred to as co-blended fabrics. These blended fabrics can be in any form and can have any amount of polyester fibers and cotton fibers. Specifically, polyester-cotton blends form the basis of many textiles or fabrics, such as bedding, sheets, towels, and clothing. The ratio of polyester to cotton in this material is not limited, but is typically 50:50, 40:60, or 35:65. The polyester component in the blended fabric can be a discrete element, including an element as small as a label or decorative component, or the polyester fiber can be integrated with the cotton fiber throughout the fabric. In some aspects, the method and system of the present invention use an integral blended fabric. In other aspects, the fabric is in fragments from the beginning. Fragments of the blended fabric can be prepared using any suitable cutting method (such as cutting, chopping, shredding, mechanical shearing, etc.). Therefore, it should be understood that the present invention is not limited to any particular type or form of polyester-cotton blended fabric.

[0035] Although the present invention is described in conjunction with blended fabrics, it should be understood that the present invention is not limited to use in recycling blended fabrics. For example, textiles or other items such as plastic bags made entirely of polyester can also be recycled using the method of the present invention. Therefore, the present invention is not limited to the recycling of any particular material.

[0036] Figure 1 The flowchart of FIG. 1 shows exemplary steps of the recovery method of the present invention. Figure 1 The steps can be regarded as the first stage of the method, which is completed by a rotating hydrolysis reactor. The illustrated method uses a hydrolysis reaction to depolymerize PET, thereby separating PET from cotton in the blended fabric material. As can be seen from the following description, Figure 1 Not all of the steps included in the method are necessary to implement the blended fabric recycling method. Furthermore, the method steps shown may be implemented in a different order. In the first step 10, polyester-cotton blended fabric waste is provided to a rotary hydrolysis reactor. Figure 5-14 An exemplary rotary hydrolysis reactor is provided that provides several important advantages and will be described in further detail below. Although the method is described as being performed on multiple pieces of polyester cotton blend fabric simultaneously, it should be understood that the method can also be performed on a single piece of polyester cotton blend fabric, although the application efficiency may be lower.

[0037] After the polyester-cotton blended fabric is loaded into the rotary hydrolysis reactor, water, a strong base, and an optional catalyst may be added to the polyester-cotton blended fabric in steps 12, 14, and 16, respectively, to provide a mixture. The strong base may hydrolyze the PET to form monomer components terephthalic acid (TPA) and ethylene glycol. The strong base may be any suitable base having a pH of 9 or higher (e.g., 9.2 or higher, 9.5 or higher, 9.8 or higher, 10 or higher, 10.2 or higher, 10.5 or higher, 10.8 or higher, 11 or higher, 11.2 or higher, 11.5 or higher, 11.8 or higher, 12 or higher, 12.2 or higher, 12.5 or higher, 12.8 or higher, 13 or higher, 13.2 or higher, 13.5 or higher, or 13.8 or higher). The upper limit of the pH is 14. The pH of the strong base may be adjusted as long as the pH is at least 9 or higher. In some aspects of the method, the strong base is an alkali metal (Group I in the periodic table) hydroxide, an alkaline earth metal (Group II in the periodic table) hydroxide, or ammonium hydroxide. Typically, the strong base is present in the form of an aqueous solution, such as a 10% or higher concentration solution (e.g., a 10% solution, a 15% solution, a 25% solution, a 40% solution, a 50% solution). In one example, the strong base is a 50% aqueous solution of sodium hydroxide or potassium hydroxide.

[0038] The amount of strong base is any effective amount that allows the hydrolysis reaction to proceed. Typically, the amount of strong base is at least 1wt% (pbw) of the total liquid composition (e.g., at least 2pbw, at least 5pbw, at least 8pbw, at least 10pbw, at least 12pbw, at least 15pbw, at least 18pbw, or at least 20pbw). Typically, the upper limit of the amount of strong base is 25pbw or lower (e.g., 20pbw or lower, 18pbw or lower, 15pbw or lower, 10pbw or lower, 8pbw or lower, 5pbw or lower, or 2pbw or lower). Any two of the aforementioned endpoints can be used to define the scope of a closed terminal, and an endpoint can also be used to define the scope of an open terminal. For example, the amount of strong base is 5-15pbw or 8-12pbw or about 10pbw.

[0039] If applicable, the catalyst may include a catalyst capable of depolymerizing PET into TPA and ethylene glycol. In some aspects, the catalyst is a phase transfer catalyst. Suitable examples of phase transfer catalysts include polymer phase transfer catalysts such as benzyltrimethylammonium chloride (BTMAC), benzyltriethylammonium chloride (BETEC), benzyltributylammonium chloride (BTBAC), tetrabutylammonium hydrogen sulfate, methyltributylammonium chloride (MTBAC), tetraethylammonium bromide (TEAB), tetrabutylammonium bromide (TBAB), or a combination thereof. In a preferred aspect, the catalyst includes benzyltributylammonium chloride (BTBAC).

[0040] The method can be designed to operate on a larger scale, including industrial scale, such as a multi-liter scale (e.g., a 300L (80 gallon) scale) and a multi-kilogram scale (e.g., a 90kg (200lb) scale). Considering this end use, after all liquids are added, the ratio of liquid to textile in the container is about 1-5L:0.25-2kg (e.g., 1.9L:0.5kg or 0.5 gallon:1.0lb).

[0041] After water, a strong base, and an optional catalyst are added to the rotary hydrolysis reactor along with the polyester-cotton blend fabric, the resulting mixture can be heated and agitated in the rotary hydrolysis reactor in steps 18 and 20. The mixture should be heated and agitated sufficiently to provide a solution / slurry containing water, terephthalic acid (TPA), ethylene glycol, and other chemicals that can be separated from the intact solid cotton free of PET and other chemical components.

[0042] The heating step can be carried out at any temperature suitable for depolymerizing the terephthalate polyester into TPA and ethylene glycol. The temperature can vary depending on the reaction conditions, such as the specific strong base and its concentration and / or the catalyst used (if any). For example, the temperature is usually about 50°C or higher (e.g., 55°C or higher, 60°C or higher, 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, 90°C or higher, 95°C or higher, 100°C or higher). In some embodiments, the temperature can be about 90-95°C. The upper limit of the heating temperature is not particularly limited, but is generally about 200°C or lower (e.g., 190°C or lower, 180°C or lower, 170°C or lower, 160°C or lower, 150°C or lower, 140°C or lower, 130°C or lower, 120°C or lower, 110°C or lower, 100°C or lower, 95°C or lower, or 90°C or lower). Any two of the aforementioned endpoints can be used to define a closed-ended range, or one endpoint can be used to define an open-ended range. For example, the heating step is performed at a temperature of 60°C or higher, 70°C or higher, 80°C or higher, 60-110°C, 70-100°C, 80-95°C, or about 93°C.

[0043] The heating and stirring duration of the mixture of blended fabric, water, highly basic and catalyst are not particularly limited. Conventionally, hydrolysis reaction lasts at least 20 minutes (for example at least 30 minutes, at least 40 minutes, at least 60 minutes, at least 90 minutes, at least 120 minutes, at least 150 minutes, at least 180 minutes, or at least 210 minutes). Conventionally, hydrolysis reaction will be completed in 240 minutes or shorter (for example 210 minutes or shorter, 180 minutes or shorter, 150 minutes or shorter, 120 minutes or shorter, 90 minutes or shorter, 60 minutes or shorter, 40 minutes or shorter, or 30 minutes or shorter) time. Any two of the aforementioned endpoints can be used to define the scope of a closed terminal, and an endpoint can also be used to define the scope of an open terminal. For example, the reaction times is about 30-60 minute, about 40-50 minute or about 40 minutes.

[0044] Once the hydrolysis reaction is complete, the solution containing TPA and ethylene glycol can be separated from the solid recovery cotton in step 22. Advantageously, the cotton / solution separation step can be performed by centrifugation using a rotating hydrolysis reactor. Alternatively, the solution can be separated from the solid recovery cotton by any suitable solid-liquid separation method. For example, the separation step can be filtration screening, separation funnel, pumping, centrifugation, or a combination of these steps.

[0045] The solid recovered cotton can be washed (e.g., with water) as in step 24 and / or dried as in step 26. In some aspects, the solid recovered cotton is washed with water to remove any residual alkali. The resulting recovered cotton can be reused for textile purposes, such as forming polyester-cotton blended fabrics, etc. If desired, the recovered cotton can be respun into yarn. Alternatively, the recovered cotton can be used to form regenerated cellulose fibers, such as viscose or sol fibers.

[0046] Optionally, as Figure 2 As shown in the flow chart of FIG. , the separated TPA and polyethylene glycol solution can be recovered and further processed to produce additional recovered products. Figure 2The step of treating as the second stage of the textile recycling method can be implemented by applying conventional reactors currently used for processing liquids / chemicals and conventional condensers and dryers already used in the chemical industry. This second stage may include step 28 of adding acid to the separated solution to precipitate TPA. The acid can be any suitable acid that can precipitate TPA from the solution. Typically, the pH of the acid is about 5 or less (e.g., 4.8 or less, 4.5 or less, 4.2 or less, 4 or less, 3.8 or less, 3.5 or less, 3.2 or less, 3 or less, 2.8 or less, 2.5 or less, or 2.2 or less). The lower limit of pH is 1. The pH value of the acid can be adjusted as long as the pH value of the acid is 5 or less. For example, the pH value range of the acid is 2-5 or 2-3. For example, the acid can be an inorganic acid or an organic acid. In some aspects, the acid is an inorganic acid, such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrobromic acid, perchloric acid, hydroiodic acid, or a combination thereof. In a preferred aspect, the inorganic acid is hydrochloric acid, sulfuric acid, nitric acid or a combination thereof. In a particularly preferred aspect, the inorganic acid is sulfuric acid.

[0047] After the TPA is precipitated, the precipitated TPA can be isolated in step 30. The precipitated TPA can be washed in step 32 (e.g., with water) and / or dried in step 34. In some aspects, the precipitated TPA is washed with water to remove any residual acid. If desired, the isolated TPA can be further purified. For example, the particle size of the isolated TPA can be changed based on the conditions under which the TPA is isolated and / or purified. If desired, the isolated TPA can be reused for polymerization with one or more diols to produce new polyesters.

[0048] Optionally, ethylene glycol can be separated from the remaining liquid in step 36. Any suitable method can be used to separate ethylene glycol. Typically, water can be first distilled from the mixture and then ethylene glycol can be distilled to separate ethylene glycol. Ethylene glycol can be further purified and then reused in additional processes, such as forming polyester. In some aspects, the water separated by distillation can be recycled and reused in the depolymerization process. Once the water and ethylene glycol are distilled, some water-soluble components in the original hydrolysis reaction may remain. These water-soluble components can include, for example, dyes and cross-linking agents, etc.

[0049] refer to Figure 3 , which gives the ability to implement Figure 1 Method of hydrolysis and cotton recovery system 40. As discussed above, Figure 3 The system includes a rotating hydrolysis reactor 42. In order to provide water for the hydrolysis reaction, the rotating hydrolysis reactor 42 is connected to a water supply facility 44 through a suitable water supply pipeline 46. The water supply facility 44 can be a water source that stores water at the pressure required by the hydrolysis process. Alternatively, as Figure 3As shown, a water pump 48 may be provided between the water supply facility 44 and the rotary hydrolysis reactor 42. A water flow meter 50 may also be provided in the water supply line 46 downstream of the water supply facility 44 to monitor the presence of water and / or the amount of water added to the rotary hydrolysis reactor 42.

[0050] In order to introduce the chemical substances necessary for the hydrolysis reaction, the rotary hydrolysis reactor 42 can be fluidly connected to the strong alkali supply facility 52 and the liquid catalyst supply facility 54. In this case, the strong alkali supply facility 52 is connected to the rotary hydrolysis reactor 42 via the alkali supply pipeline 56, and the catalyst supply facility 54 is connected to the rotary hydrolysis reactor 42 via the catalyst supply pipeline 58. Alternatively, one or two chemicals can be added to the rotary hydrolysis reactor 42 manually. Specifically, depending on the scale of the recovery operation and the amount of catalyst used, manual addition of the catalyst may be more preferred. In the illustrated embodiment, an alkali metering pump 60 and an alkali flowmeter 62 are provided in the alkali supply pipeline 56 to monitor and measure the amount of alkali added to the rotary hydrolysis reactor 42. A catalyst metering pump 64 and a catalyst flowmeter 66 are similarly provided in the catalyst feed pipeline 58 to monitor and measure the amount of catalyst added in the reactor 42.

[0051] exist Figure 3 In, the supply of polyester cotton blended fabric waste 68 is also schematically provided.This supply can take any required form, for example transport container or other storage container.The pipeline 70 connecting fabric waste supply facility 68 and rotary hydrolysis reactor 42 has represented any suitable method that fabric waste is transported or delivered to reactor.In one embodiment, use overhead sling that fabric waste is transported in the rotary hydrolysis reactor 42, and described overhead sling can be a part of sling conveying system.Also can use other types of conveyor or wheeled cart system.But when reclaiming a large amount of polyester cotton blended fabric waste, overhead sling system may have special advantage.

[0052] After the hydrolysis reaction is completed, the solid recovered cotton can be transported from the rotary hydrolysis reactor 42 to the dryer 71, and the separated TPA and ethylene glycol solution can be transported to the hydrolyzate recovery system through pipeline 128 (see Figure 4 ). In some embodiments, dryer 71 may be a conventional gas-fired dryer, such as those used in industrial laundry facilities. Figure 3 The line 73 from the rotary hydrolysis reactor 42 to the dryer 71 is used to represent any suitable method of transporting the recycled cotton to the dryer 71. According to one embodiment, a conveyor system is used to transport the recycled cotton to the dryer 71. Other types of transport systems, such as wheeled carts or hoppers, may also be used.

[0053] Figure 5-14An exemplary embodiment of a rotating hydrolysis reactor 42 for use in a mixed textile recycling process is provided. In the depicted embodiment, the hydrolysis reactor 42 includes a reactor housing 72, which in this case is arranged on a support frame 74 (see, for example, Figure 6 ). The illustrated support frame 74 includes a base 76 designed to engage the ground and a pair of laterally spaced front legs 78 extending upwardly from the base 76 to an upper arm assembly 80. To provide further structural support to the support frame 74, a pair of cross braces 82 are also provided, each cross brace 82 extending between the lower end of a corresponding front leg 80 and the upper arm assembly 80. As described in more detail below, while the illustrated support frame 74 has certain advantages in loading and unloading a hydrolysis reactor compared to conventional reactors, it should be understood that support frames having other structures may also be used.

[0054] The reactor housing 72 defines an interior cavity 84 for agitating the textile material, water and reaction chemicals during the hydrolysis reaction stage and for extracting liquid from the recycled cotton during the cotton recovery stage. Fig.10 and 11 As shown, the inner cavity 84 supports an inner drum 86 that rotates relative to the reactor shell 72. The inner cavity 84 of the reactor shell 72 provides a space for receiving and containing water and chemicals related to the depolymerization reaction, while the inner drum 86 receives and contains the textile waste. In order to allow the water and chemicals in the inner cavity 84 to enter and exit the inner drum 86, a plurality of holes 90 are opened on the side wall 88 of the inner drum 86. Figure 12-14 As best shown in FIG. 1 , the interior of the rotating inner drum 86 may also include a plurality of circumferentially spaced ribs 92 disposed within the interior of the sidewall 88 to aid in agitating the fabric waste, water, and chemicals. In the illustrated embodiment, the inner drum 86 is equipped with four ribs 92 (see FIG. Fig.13 ), which are equally spaced along the circumference of the inner drum 86. Fig.14 As shown, each rib 92 can be provided with opposite sides 93, which are angled so that they are close to each other when they extend inwardly from the side wall 88 of the inner drum 86. In the illustrated embodiment, the end of each side 93 has a flat end face 95. Other structures of ribs 92 can also be applied. The inner drum 86 can have any desired capacity. For example, in one embodiment, the inner drum 86 and the reactor shell 72 are designed to have a capacity that can accommodate up to about 1000lb of textile waste. The reactor shell 72 and the inner drum 86 can be made of any suitable corrosion-resistant material such as stainless steel.

[0055] Compared with conventional hydrolysis reactors, the use of a rotating inner drum 86 with ribs 92 has many advantages. For example, the mechanical agitation generated by the rotating inner drum 86 and the ribs 92 can implement effective polymerization reactions with less water and reaction chemicals. In this way, this allows the method to be efficiently implemented in a higher capacity, higher energy efficiency and more cost-effective manner. In some embodiments, the rotary hydrolysis reactor of the present invention can use as little as 1 / 12 of the water of a conventional reactor. Compared with conventional reactors, the rotary hydrolysis reactor of the present invention also allows the size of a single piece of fabric waste to be relatively large, and in order to implement sufficient agitation, conventional reactors usually need to crush the fabric waste before adding it to the reactor. The design of the inner drum 86 with ribs 92 also helps to recycle high-quality cotton fibers, which can be used to produce a variety of high-value products. In addition, the mechanical agitation provided by the rotating inner drum 86 and the ribs 92 not only promotes depolymerization, but also helps to mechanically remove non-polyester components in the fabric waste, such as zippers, buttons, labels and / or decorative parts. The design of the inner drum 86 and the ribs 92 is also easier to clean than the agitators used in conventional hydrolysis reactors, thereby greatly reducing production downtime and maintenance costs.

[0056] To drive the internal drum 86 to rotate relative to the reactor housing 72, the illustrated reactor 42 includes a rotation drive assembly 94, which in this case includes an electric motor 96 operably connected to a drive shaft 98 of the internal drum 86 (see, for example, Figure 6 , 10 and 11). Fig.12 86. The arrangement of the drive shaft 98 and the internal drum 86 can also be seen in FIG. Depending on the different stages of the hydrolysis process, the rotary drive assembly 94 can be configured to rotate the internal drum 86 at different speeds relative to the reactor housing 72. For example, during the depolymerization reaction, the internal drum 86 can be rotated in a certain manner relative to the reactor housing 72 to optimize the agitation of the textile waste, water and reaction chemicals. Then, in the separation step, the internal drum 86 can be rotated at a higher speed to generate sufficient centrifugal force to separate the liquid TPA and ethylene glycol solution from the solid recycled cotton. This centrifuged liquid flows out of the internal drum 86 through the holes in the side wall 88 of the internal drum 86. The separated liquid is then collected in the reactor housing 72 and removed from the rotary hydrolysis reactor 42 by an internal drainage pump equipped in the reactor. According to one embodiment, the internal drum 86 and the drive assembly 94 are constructed so that the rotation speed of the internal drum 86 can reach up to about 500 rpm.

[0057] In order to maintain the water and chemicals at the desired temperature for the hydrolysis reaction, the rotary hydrolysis reactor 42 may be equipped with a slurry heating system 170 . Fig. 9 One embodiment of a suitable slurry heating system 170 is given in . Fig. 9 The slurry heating system 170 in the rotary hydrolysis reactor 42 uses a pump 172 to extract water and chemical slurry from the bottom 174 of the rotary hydrolysis reactor 42 through an outlet line 176. The outlet line 176 guides the slurry to the inlet end 178 of the heat exchanger 180, which is operated to heat the slurry to the temperature required for the hydrolysis reaction. In this case, the heat exchanger 180 is heated by a steam generator 182. Steam from the steam generator 182 is guided into the heat exchanger 180 through a steam supply line 184 and can be controlled by a steam control valve 186. The heated slurry flows out of the outlet end 188 of the heat exchanger 180 and flows back to the upper part 190 of the rotary hydrolysis reactor 42 through a slurry inlet line 192. The cooled condensed water flows out of the heat exchanger 180 through a condensate outlet 194. In operation, the slurry heating system 170 draws in cooled slurry from the bottom 174 of the reactor 42, heats the slurry to a desired temperature, and then redirects the hot slurry to the upper portion 190 of the reactor 42. The slurry heating system 170 can be controlled to maintain the slurry in the reactor at a desired temperature. Although a steam heat exchanger is shown in the figure, it should be understood that other devices other than steam heat exchangers can be used to implement heating.

[0058] In order to load the polyester cotton blended fabric waste into the inner drum 86, Figure 5-8 , Fig.10 and Fig.11 The illustrated rotary hydrolysis reactor 42 includes a movable outer door 108. More specifically, the outer door 108 is pivotally connected to the reactor housing 72 so as to move between an open and closed position relative to a door opening 110 in the wall of the reactor housing 72. In the open position, the door opening 110 in the reactor housing 72 can be used to load and unload textile waste into and out of the inner drum 86 (see, for example, FIG. Fig.10 In the closed position (see e.g. Figure 5 ), the outer door 108 closes the door opening 110 in the reactor housing 72 so that the depolymerization and hydrolysis reaction can be carried out safely and efficiently. Figure 5 As shown, the outer door 108 is hinged at the side so that the outer door 108 pivots laterally between the open and closed positions, although other door hinge structures may be used. To ensure that the outer door 108 maintains a tight seal with the door opening 110 in the reactor housing 72, a sealing assembly may be provided on the periphery of one or both of the outer door 108 and the door opening 110. The sealing assembly may be specifically designed so as to be usable for the chemicals used in the depolymerization process.

[0059] To further facilitate loading of textile waste into the inner drum 86, the reactor support frame 74 may be designed so that the front end of the reactor housing 72 may be oriented from a normal horizontal operating position (e.g. Figure 6 As shown) tilt upward to Figure 7 This upwardly tilted loading position is particularly useful when loading the reactor 42 via an overhead sling. To further facilitate unloading the recovered solid cotton from the internal drum 86 at the end of the hydrolysis process, the reactor support frame 74 can be designed so that the front end of the reactor housing 72 can be tilted downward from the normal horizontal orientation operating position to a position such as Figure 8 The unloading position shown. This downwardly inclined unloading position is particularly useful when the recycled cotton is unloaded onto a belt conveyor for transport to a dryer 71 or the like. Figure 6-8 In the illustrated embodiment, movement between the loading, operating and unloading positions is achieved by a pivot connection 112 between the front legs 78 of the support frame 74 and the support frame base 76. To allow the front legs 78 to pivot relative to the base 76, at least one tilting push rod 114 may be provided between the reactor housing 72 and the base 76 of the support frame 74. In this case, the tilting push rod 114 is designed so that extension and retraction of the push rod can pivot the legs 78 relative to the base 76, thereby moving the reactor housing 72 between different positions.

[0060] As an alternative to hinged outer doors, in order to facilitate loading of textile waste into the inner drum 86, particularly from overhead slings, the rotary hydrolysis reactor 42 may be equipped with a Fig.15 and Fig.16 The hopper assembly 116 shown. More specifically, the hopper assembly 116 can be mounted on the front side of the reactor housing 72, covering the front opening 110 of the reactor housing 72. In this case, the hopper assembly 116 includes an upwardly opening chute 118, and the upper end of the chute 118 has a hopper door 120 that can move between an open position and a closed position. Fig.16 In the lowered closed position shown, the hopper door 120 blocks the upper end of the slide 118. Fig.16 As shown in FIG. 1 and FIG. 2 ), the closed position of the chute door 120 is used for both the operating position of the reactor 42 and the hopper door 120 seals the rotating hydrolysis reactor 42, thereby implementing the depolymerization process. Fig.15 As shown, when the hopper door is raised to the open position, the open upper end of the chute 118 is unobstructed and the fabric material can be loaded into the chute 118, thereby guiding the fabric material through the door opening of the reactor housing 72 and into the internal drum 86. A door drive device can be provided to pivot the hopper door between the open and closed positions.

[0061] To enable the recycled cotton to be unloaded from the internal drum, the hopper assembly 116 can be supported on the reactor housing 72 so as to move between a lowered and raised position. In the lowered position, the chute 118 is disposed near the front end of the reactor housing 72. In this position, when the reactor housing 72 is in the loading position, the chute 118 can be used to load the rotary hydrolysis reactor (see Fig.15 ). The lowered position of the chute is the position used during reactor operation. Fig.16 As shown, in the raised position, the hopper chute 118 is pivoted upward relative to the reactor housing 42, away from the opening of the reactor housing. This raised position enables the rotary hydrolysis reactor 42 to be unloaded after a hydrolysis cycle without interference from the hopper assembly 116. The movement of the hopper assembly 116 between the raised and lowered positions can be driven by one or more hopper tilt actuators 122 (see Fig.16 ).

[0062] The ability to move the reactor between loading and unloading positions allows the rotary hydrolysis reactor to be used in conjunction with a high-capacity conveying system for both loading and unloading, thereby enabling the reactor to effectively process very large quantities of textile waste, especially when compared to conventional hydrolysis reactors. Additionally, this arrangement allows large quantities of material to be loaded and unloaded quickly and easily with minimal manpower. In certain applications, a hopper assembly can further facilitate loading of the reactor. Thus, the rotary reactor housing provides a hydrolysis method that can be easily scaled up and can accommodate large volumes of recycled textile waste.

[0063] Reference Figure 4 The figure shows the Figure 2 After the hydrolysis reaction is completed, the system recovers TPA and ethylene glycol from the liquid solution separated from the solid recovery cotton. In the illustrated embodiment, the recovery system 124 includes a recovery container 126, which is configured to receive the liquid hydrolyzate from the rotary hydrolysis reactor 42. Figure 4 As shown, the liquid hydrolyzate can be drawn from the rotating hydrolysis reactor 42 through pipeline 128. In order to keep the solution well mixed during the treatment process, the recovery container 126 can be equipped with a suitable agitator 130. The recovery container 126 can also be equipped with a heating system 132 for heating the contents of the recovery container as needed. In order to monitor the temperature of the contents of the recovery container 126, a temperature sensor 134 can also be provided.

[0064] The acid supply facility 136 is also in communication with the recovery vessel 126 via a line 138. An acid metering pump 140 may be provided in the line 138 to control the delivery of acid to the recovery vessel 126. In addition, a pH meter 142 may be provided in the recovery vessel 126 to monitor the pH of the solution in the recovery vessel 126 as the acid is added and thereby detect when the pH of the solution in the recovery vessel 126 drops to a point where TPA precipitates from the hydrolyzate solution.

[0065] Once the pH in the recovery vessel 126 reaches the desired level, the hydrolyzate in the recovery vessel 126 can be introduced, such as via line 144 and recovery vessel pump 146, and passed through a TPA recovery filter 148. The TPA recovery filter 148 can be configured to retain TPA precipitates as the hydrolyzate passes through the filter. After passing through the filter, the remaining liquid can be circulated back to the recovery vessel 126 via a recirculation line 150. The hydrolyzate can be circulated through the recovery vessel 126 and the TPA recovery filter 148 until substantially all of the TPA precipitates are removed. In the illustrated embodiment, the TPA recovery filter 148 can be connected to a water supply 152 via a water supply line 153 to wash the filter cake in the TPA recovery filter 148 after separation of the precipitated TPA is complete. To facilitate this washing step, the TPA recovery filter 148 can be equipped with inlet and outlet valves that, when closed, isolate the TPA recovery filter 148 from the rest of the system as water flows into the filter. The washed TPA precipitates can then be transported to a dryer 154. Figure 4 Such transport is schematically indicated in FIG. 1 by line 156, which refers to any method of transport to dryer 154, including manual transport of the TPA precipitate.

[0066] Once the TPA precipitate has been separated, the recovery vessel 126 can begin heating the remaining contents in preparation for distilling water from the ethylene glycol and then distilling the ethylene glycol from the remaining salts and compounds. During the distillation process, the agitator 130 in the recovery vessel can continue to operate. Once the water in the hydrolyzate in the recovery vessel 126 is boiled off, the temperature in the recovery vessel can be raised to the boiling point of the ethylene glycol, thereby separating the ethylene glycol from the salts and other impurities. The ethylene glycol vapor is then introduced into the ethylene glycol recovery condenser 158. The ethylene glycol recovery condenser 158 can be cooled by any suitable means, such as circulating a coolant. After condensation, the ethylene glycol can be drawn from the condenser 158 and enter a suitable storage container 160.

[0067] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0068] Unless otherwise specified herein or clearly contradicted by the context, in the context of describing the present invention (especially in the context of the following claims), the terms "a" and "an", "the" and "at least one" and similar references should be interpreted as including the singular and the plural. Unless otherwise specified herein or clearly contradicted by the context, the term "at least one" followed by a list of one or more items (e.g., "at least one of A and B") should be understood as selecting one item from the listed items (A or B) or any combination of two or more listed items (A and B). Unless otherwise specified, the terms "including", "having", "including" and "containing" should be understood as open terms (i.e., "including but not limited to"). Unless otherwise specified herein, the citation of numerical ranges herein is only used as a shorthand method to refer individually to each individual value falling within the range, and each individual value is included in the specification as if it were individually quoted herein. Unless otherwise specified herein or clearly contradicted by the context, all methods described herein can be implemented in any suitable order. Unless otherwise required, the use of any and all examples or exemplary language (such as "for example") provided herein is only for better explanation of the present invention and does not constitute a limitation on the scope of the present invention. No language in the specification should be construed as indicating that any unrequired element is essential to the implementation of the present invention.

[0069] Preferred embodiments of the present invention are described herein, including the best mode of implementing the present invention known to the inventor. After reading the above description, those of ordinary skill in the art may recognize that these preferred embodiments can be changed. The inventors hope that the technicians will appropriately adopt these changes, and the inventors expect that the present invention will be implemented in a manner other than the specific description herein. Therefore, the present invention includes all adjustments and equivalents of the subject matter described in the appended claims as allowed by applicable law. In addition, unless otherwise stated herein or clearly contradictory to the context, the present invention includes any combination of the above elements with all possible variations thereof.

Claims

1. A method for treating polyester-cotton blended fabric waste, comprising: Adding polyester-cotton blended fabric waste into a rotating drum of a rotary hydrolysis reactor, wherein the rotating drum has a plurality of ribs arranged on its inner surface; adding water and base to a rotary hydrolysis reactor; heating the water and base added to the rotary hydrolysis reactor; agitating the polyester-cotton blended fabric waste with a plurality of ribs by rotating an inner drum relative to a rotating hydrolysis reactor housing, thereby hydrolyzing the PET into a TPA and ethylene glycol solution and solid recycled cotton free of PET; Separating the TPA and ethylene glycol solution from the solid recovery cotton, and directing the separated TPA and ethylene glycol solution to a hydrolyzate recovery container; adding acid to the separated TPA and ethylene glycol solution in a hydrolyzate recovery vessel to precipitate TPA; separating the precipitated TPA from the remaining liquid in a hydrolysate recovery vessel; and The ethylene glycol is separated from the remaining liquid in the hydrolysate recovery vessel.

2. The method of claim 1, wherein the pH of the base is 9 or higher.

3. The method of claim 2, wherein the base comprises 10% or more of an aqueous solution.

4. The method of claim 1 further comprising the step of adding a catalyst to the rotary hydrolysis reactor.

5. The process of claim 4, wherein the catalyst is a phase transfer catalyst.

6. The method of claim 1, wherein after adding water and alkali, the ratio of liquid to textile waste in the base is 1-5 L liquid: 0.25-2 kg textile waste.

7. The process of claim 1 wherein the water and base are heated to about 50°C or higher in the rotary hydrolysis reactor.

8. The process of claim 1 wherein the water and base are heated to about 90-95°C in the rotary hydrolysis reactor.

9. The method of claim 1, wherein the hydrolysis reaction is completed in 60 minutes or less.

10. The method of claim 1, further comprising the step of washing the solid recycled cotton.

11. The method of claim 1 wherein the pH of the acid is about 5 or less.

12. The method of claim 1, further comprising a washing step of the precipitated TPA.

13. The method of claim 1, wherein in the step of separating TPA and ethylene glycol from the solid recycled cotton, the rotation speed of the rotating drum is relatively higher than that of the agitating step.

14. A rotary hydrolysis reactor for treating polyester-cotton blended fabric waste, comprising: a reactor housing defining an interior cavity for receiving water and a chemical slurry associated with a hydrolysis reaction; an inner drum supported in the inner cavity, rotating relative to the reactor housing and adapted to receive the polyester-cotton blended fabric waste, the inner drum including a side wall having a plurality of apertures; a plurality of spaced ribs supported on the inner surface of the inner drum sidewall for agitating the polyester-cotton blend waste as the inner drum rotates relative to the reactor housing; The slurry heating system includes a slurry outlet pipeline connected to the inner cavity of the reactor shell, which is used to extract water and chemical slurry from the bottom of the reactor shell. The slurry outlet pipeline guides the water and chemical slurry to a heat exchanger. The heat exchanger can be operated to heat the water and chemical slurry to a desired temperature. The slurry heating system also includes a slurry inlet pipeline connected to the reactor shell, and the pipeline is designed to guide the heated water and chemical slurry from the heat exchanger back to the inner cavity of the reactor shell.

15. The rotary hydrolysis reactor of claim 14, further comprising a rotary drive assembly for rotating the internal drum relative to the reactor housing at a variable speed.

16. The rotary hydrolysis reactor of claim 14, wherein the reactor shell is supported on a support frame, the support frame being arranged to tilt the reactor shell between a loading position, an operating position, and an unloading position.

17. The rotary hydrolysis reactor of claim 14, further comprising a hopper assembly disposed on the front side of the reactor shell, the hopper assembly overlying the front opening of the reactor shell, and wherein the hopper assembly comprises a chute with a hopper door at the upper end of the chute.

18. A system for treating polyester-cotton blended fabric waste, comprising: A rotary hydrolysis reactor, the reactor comprising: a reactor housing defining an interior cavity for receiving water and a chemical slurry associated with a hydrolysis reaction; an inner drum supported in the inner cavity, rotating relative to the reactor housing and adapted to receive the polyester-cotton blended fabric waste, the inner drum including a side wall having a plurality of apertures; a plurality of spaced ribs supported on the inner surface of the inner drum sidewall for agitating the polyester-cotton blend waste as the inner drum rotates relative to the reactor housing; and A hydrolyzate recovery system is configured to receive liquid hydrolyzate from the rotary hydrolysis reactor, comprising: a recovery container configured to receive liquid hydrolyzate from the rotary hydrolysis reactor, wherein the recovery system includes an agitator and a heating system; an acid supply system for directing the acid to a recovery vessel; A TPA recovery filter designed to capture TPA precipitate when liquid hydrolysate is directed from the recovery vessel through the TPA recovery filter; and The ethylene glycol recovery condenser communicated with the recovery container is used to receive the ethylene glycol vapor from the recovery container and condense it into liquid.

19. The system of claim 18, wherein the rotary hydrolysis reactor comprises a slurry heating system, the heating system comprising a slurry outlet line connected to the inner cavity of the reactor shell for extracting water and chemical slurry from the bottom of the reactor shell, the slurry outlet line directing the water and chemical slurry to a heat exchanger, the heat exchanger being operable to heat the water and chemical slurry to a desired temperature, the slurry heating system further comprising a slurry inlet line connected to the reactor shell, and the line being designed to direct the heated water and chemical slurry from the heat exchanger back to the inner cavity of the reactor shell.

20. The system of claim 19, further comprising a recycle line directing the remaining liquid portion back to the recovery vessel after passing through the TPA recovery filter.

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