Carbon nanotube efficient purification method and device based on electromagnetic heating and waste heat recovery

Abstract

The invention discloses an efficient carbon nanotube purification method and device based on electromagnetic heating and waste heat recovery, and the method comprises the following steps: collecting high-temperature waste liquid in a first reaction kettle, and carrying out waste heat recovery by utilizing a heat exchanger, so as to heat fresh acid liquid in a heating pipeline of a next-stage reaction kettle in combination with electromagnetic heating; the raw materials are subjected to acid pickling in the next-stage reaction kettle through acid liquor obtained after waste heat recovery, the processes of waste heat recovery, heating and acid pickling are repeated till the raw materials are subjected to final acid pickling through the last-stage reaction kettle, and the purified carbon nanotubes are obtained; a plurality of groups of pickling data are collected, and purity curves and energy efficiency curves of the carbon nanotubes with different pickling times are constructed, so that the set number of the reaction kettles is optimized. By means of the scheme, secondary utilization of a heat source can be conducted, the number of the reaction kettles is optimized, energy waste is reduced, and cost is saved.

Description

Technical Field

[0001] The present application relates to the field of carbon nanotube purification, and in particular to a method and device for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery. Background Art

[0002] Carbon nanotubes have shown great application potential in many fields due to their unique physical and chemical properties. However, impurities such as metal catalysts and amorphous carbon are inevitably introduced during their production process, which seriously affect the performance and application of carbon nanotubes. Therefore, the acid washing and purification of carbon nanotubes has become a crucial research topic. Acid washing and purification can not only effectively remove metal catalyst residues and amorphous carbon in carbon nanotubes, but also improve the dispersion and functionalization of carbon nanotubes, thereby significantly improving their application effects in composite materials, electronic devices, energy storage and other fields. The importance of acid washing and purification is reflected in the fact that it is a key step in obtaining high-purity and high-quality carbon nanotubes, which directly affects the performance and reliability of subsequent applications.

[0003] At present, the acid washing and purification of carbon nanotubes mainly adopts wet acid washing technology, which works by treating carbon nanotubes with strong acid (such as sulfuric acid, nitric acid or their mixture) under high temperature conditions, dissolving metal catalysts through the oxidation of acid, and removing amorphous carbon. However, this traditional acid washing method has some significant problems: first, the acid washing process is time-consuming, usually taking several hours or even days; second, the operation under high temperature and high pressure conditions has safety hazards; third, the use of a large amount of strong acid not only causes environmental pollution, but also increases production costs; finally, the acid washing process may cause a certain degree of damage to the carbon nanotube structure, affecting its inherent properties.

[0004] In order to solve the above problems, researchers have disclosed a variety of improvement methods. For example, ultrasound-assisted pickling can accelerate the reaction process and shorten the processing time; microwave-assisted pickling can achieve rapid and uniform heating and improve purification efficiency; electrochemical pickling enhances the oxidation ability of the acid by applying an electric field, reducing the amount of acid and the reaction temperature. However, these methods still have some defects. First, most of these methods only focus on the optimization of a single reactor and fail to fully utilize the advantages of multi-stage reactions; second, they often ignore the issue of energy efficiency, especially heat recovery in continuous production processes; third, these methods require the introduction of additional equipment or energy input during implementation, which increases the process and cost.

[0005] Therefore, there is an urgent need for a technical solution that can reuse heat sources, optimize the number of reactors, reduce energy waste, and save costs. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the embodiments of the present application provide a method and device for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery. The present application solves the technical problems that the heat source in the waste liquid discharged by the prior art will cause energy waste.

[0007] The embodiment of the present application provides a method for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery, comprising: setting up at least two reactors for pickling, the reactors being provided with a feed port, a discharge port, a liquid discharge port, a stirring device and / or a temperature sensor; configuring an independent electromagnetic heating pipeline for each reactor, the electromagnetic heating pipeline being used to heat and transport acid liquid; adding carbon nanotube raw material into a first reactor, and heating the acid liquid by using the electromagnetic heating pipeline to pickle the raw material; collecting high-temperature waste liquid in the first reactor, and recovering waste heat by using a heat exchanger, so as to heat the fresh acid liquid in the heating pipeline of the next reactor in combination with electromagnetic heating; pickling the raw material by using the acid liquid recovered by waste heat in the next reactor, and repeating the process of waste heat recovery, heating and pickling until the raw material is finally pickled by the final reactor to obtain purified carbon nanotubes; collecting multiple sets of pickling data, and constructing purity curves and energy efficiency curves of carbon nanotubes with different pickling times to optimize the number of reactors to be set.

[0008] In a possible implementation, an independent electromagnetic heating pipeline is configured for each reactor, and the electromagnetic heating pipeline is used to heat and transport the acid solution, including: configuring an electromagnetic heating pipeline system, including an electromagnetic heater, a stainless steel coil, a PTFE lining, an insulation layer, a temperature sensor and a flow meter, wherein the electromagnetic heater adopts high-frequency electromagnetic induction heating; the inner diameter of the stainless steel coil is set to 20 mm, the wall thickness is set to 2 mm, and it is coiled into a spiral shape, a 1 mm thick PTFE layer is coated on the inner wall of the stainless steel tube, and a 50 mm thick glass wool insulation layer is wrapped on the outside of the coil; a temperature sensor is installed at the inlet and outlet of the coil, and an electromagnetic flowmeter is installed at the inlet of the coil; the outlet temperature of the acid solution is controlled by adjusting the flow rate and heating power to stabilize it within the set range.

[0009] In a possible implementation, a carbon nanotube raw material is added to a first reaction kettle, and an acid solution is heated by an electromagnetic heating pipe to pickle the raw material, including: the acid solution prepared by mixing the acid components in a preselected acid solution formula according to a predetermined volume ratio is heated to a predetermined temperature through an electromagnetic heating pipe system; a pre-weighed amount of dry carbon nanotube raw material is slowly added to the acid solution heated to the predetermined temperature, and stirred at a predetermined speed; the pickling reaction is continued at the predetermined temperature for a predetermined time, and intermittent sampling is performed to detect changes in impurity content; heating and stirring are stopped, and after the reaction mixture is naturally cooled to a predetermined temperature, solid-liquid separation is performed by a centrifuge; the separated carbon nanotubes are repeatedly washed with deionized water until the pH value of the washing liquid reaches a predetermined range; and the washed carbon nanotubes are vacuum dried at a predetermined temperature for a predetermined time.

[0010] In a possible implementation, high-temperature waste liquid in the first reactor is collected, and waste heat is recovered by using a heat exchanger to heat the fresh acid liquid in the heating pipe of the next reactor in combination with electromagnetic heating, including: discharging the high-temperature waste liquid after pickling in the first reactor and collecting it in an insulation tank of a preset capacity; setting a heat exchanger with a target material, a predetermined heat exchange area and a heat transfer coefficient in the heating system of the next reactor; using a corrosion-resistant pump to transport the waste liquid from the insulation tank to the heat exchanger at a preset flow rate, and heat exchanging with the low-temperature fresh acid liquid entering the next reactor, so that the waste liquid is cooled and the fresh acid liquid is heated; the preheated fresh acid liquid is further heated to the target temperature through the heating pipe system, and the waste liquid that has completed the heat exchange is transported to the waste liquid treatment system for neutralization treatment.

[0011] In a possible implementation, the raw material is pickled with acid liquid recovered from waste heat in the next-stage reactor, and the waste heat recovery, heating and pickling processes are repeated until the raw material is finally pickled by the final reactor to obtain purified carbon nanotubes, including: transferring the carbon nanotubes after the initial pickling to the next-stage reactor, adding newly prepared acid liquid after waste heat recovery and electromagnetic heating for secondary pickling; repeating pickling, waste heat recovery and electromagnetic heating of waste liquid until the product is transferred to the final reactor, and finally pickling with low-concentration acid liquid; rinsing the carbon nanotubes with deionized water until the pH value is neutral, grinding the dried carbon nanotubes with a ball mill, and sieving with a sieve with a preset mesh size to remove large particle impurities to obtain purified carbon nanotubes.

[0012] In a possible implementation, multiple groups of pickling data are collected, and purity curves and energy efficiency curves of carbon nanotubes with different pickling times are constructed to optimize the number of reactors to be set, including: collecting multiple groups of carbon nanotube samples, and performing pickling treatments on each group of samples for different times, wherein the number of pickling times varies within a preset range; measuring the purity, treatment quality, actual energy consumption and waste heat recovery of the carbon nanotubes for the samples after each pickling, and recording the pickling operation parameters; fitting the purity prediction model parameters using a nonlinear regression method, and drawing a curve of the change of carbon nanotube purity with the number of pickling times; calculating the energy utilization efficiency of each group of experiments, and drawing a curve of the change of energy efficiency with the number of pickling times; constructing a comprehensive performance index, combining the purity improvement function with the energy efficiency function, and setting a weight coefficient to determine the relative importance of purity and energy efficiency; calculating the corresponding comprehensive performance index value for each pickling number within the preset range; checking whether the purity requirements and the minimum energy efficiency constraints are met; and selecting the value that maximizes the comprehensive performance index among the pickling times that meet the constraints as the optimal pickling times and the target configuration number of reactors.

[0013] In one possible implementation, a comprehensive performance index is constructed, the purity improvement function is combined with the energy efficiency function, and a weight coefficient is set to determine the relative importance of purity and energy efficiency, including: Where J(n) represents the comprehensive performance index of pickling times n, w1 and w2 represent weight coefficients, f(P(n)) represents the purity improvement function, g(η(n)) represents the energy efficiency function, P(n) represents the purity of pickling times n, P initial represents the initial purity, P0 represents the theoretical maximum purity, η(n) represents the energy efficiency of pickling times n, η max represents the maximum energy efficiency observed in the experiment.

[0014] An embodiment of the present application also provides a carbon nanotube efficient purification device based on electromagnetic heating and waste heat recovery, which is used to implement the carbon nanotube efficient purification method as described in any of the above embodiments, and is characterized in that it includes: at least two reactors, one or more electromagnetic heating pipes and a heat exchanger; wherein the reactor is provided with a feed inlet, a discharge port, a liquid discharge port, a stirring device and / or a temperature sensor; each reactor is equipped with an independent electromagnetic heating pipe; the electromagnetic heating pipe is used to heat and transport acid liquid; the heat exchanger is used to recover waste heat to heat the fresh acid liquid in the heating pipe of the target reactor.

[0015] In the above-provided method and device for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery, the embodiment of the present application realizes efficient pickling process by setting up multiple reactors and utilizing electromagnetic heating technology. The application of electromagnetic heating technology not only improves the heating efficiency, but also realizes precise control of the reaction temperature, which is beneficial to improving the consistency of product quality. Secondly, through the waste heat recovery system, the thermal energy in the waste liquid is fully utilized, the energy utilization efficiency is improved, and the energy consumption and production costs are significantly reduced. Furthermore, in some embodiments, by combining purity and energy efficiency ratio, the number of reactors can be optimized to balance energy consumption and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of a process for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery provided in an embodiment of the present application;

[0018] Figure 2 A schematic diagram of a purity curve provided in an embodiment of the present application;

[0019] Figure 3 A schematic diagram of an energy efficiency curve provided in an embodiment of the present application;

[0020] Figure 4 A schematic block diagram of a carbon nanotube efficient purification device based on electromagnetic heating and waste heat recovery provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0022] Those skilled in the art will appreciate that the terms "first", "second" and the like in the embodiments of the present application are only used to distinguish different steps, devices or modules, etc., and do not represent any specific technical meaning, nor do they represent the necessary logical order between them. It should also be understood that in the embodiments of the present application, "multiple" may refer to two or more, and "at least one" may refer to one, two or more. It should also be understood that for any component, data or structure mentioned in the embodiments of the present application, in the absence of explicit limitation or contrary revelation given in the context, it can generally be understood as one or more. In addition, the term "and / or" in the present application is only a kind of association relationship describing the associated objects, indicating that there can be three kinds of relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present application generally indicates that the associated objects before and after are an "or" relationship. It should also be understood that the description of each embodiment in the present application emphasizes the differences between the embodiments, and the same or similar parts can refer to each other. For the sake of brevity, they will not be repeated one by one.

[0023] At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. The techniques, methods and devices known to ordinary technicians in the relevant fields may not be discussed in detail, but where appropriate, the techniques, methods and devices should be considered as part of the specification. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] Figure 1 A schematic flow chart of a highly efficient carbon nanotube purification method based on electromagnetic heating and waste heat recovery provided in the embodiment of the present application. The method aims to solve the problems of energy waste and high cost in the existing carbon nanotube purification process, and achieves high efficiency and low energy consumption in the carbon nanotube purification process by combining the process design and equipment configuration of electromagnetic heating and waste heat recovery.

[0026] First of all, it is important to understand that carbon nanotubes are a type of nanomaterial with a unique structure and excellent properties, and their purification process is crucial to improving the quality and performance of the material. Acid washing purification is a key step in the production of carbon nanotubes, and its purpose is to remove impurities and impure substances on the surface of carbon nanotubes, thereby improving their purity and performance. Traditional acid washing purification methods are usually carried out in a heated environment, such as acid washing reactions at a temperature of around 70°C. However, this method suffers from the problem of low energy efficiency, because the temperature of the discharged waste liquid is usually still maintained at around 50°C, and this part of the heat energy is not fully utilized, resulting in energy waste and increased production costs.

[0027] The technical solution disclosed in this application aims at the above-mentioned problems and designs a highly efficient carbon nanotube purification method based on electromagnetic heating and waste heat recovery. The core idea of ​​this method is to improve energy utilization efficiency by setting up multiple reactors and utilizing waste heat from waste liquid. Specifically, this method includes but is not limited to the following key steps.

[0028] like Figure 1 As shown, at step S101, at least two reactors for pickling are provided, and the reactors are provided with a feed port, a discharge port, a liquid discharge port, a stirring device and / or a temperature sensor. These reactors are the main containers for pickling and purification of carbon nanotubes, and each reactor is provided with a feed port, a discharge port, a stirring device and / or a temperature sensor, and a liquid discharge port is provided at the bottom. The feed port is used to add carbon nanotube raw materials and acid solution to the reactor; the discharge port is used to take out the purified carbon nanotubes; the stirring device is used to ensure that the reaction is fully uniform during the pickling process; the temperature sensor is used to monitor the reaction temperature in real time; and the liquid discharge port is used to discharge the waste liquid after the reaction. This design ensures efficient and precise control of the pickling process.

[0029] Before obtaining the target configuration quantity, the method for determining the number of reactors may include: Where N represents the number of reactors required, C i represents the initial impurity concentration, C f represents the target final impurity concentration, k represents the reaction rate constant, t represents the reaction time of a single reactor, T represents the reaction temperature, V represents the reactor volume, Represents the ceiling function.

[0030] The formula in the present embodiment is based on first-order reaction kinetics, assuming that impurity removal follows an exponential decay law. The impurity removal efficiency of each reactor is related to the reaction time, temperature and volume. Specifically, C i : Initial impurity concentration, determined according to the purity of the raw carbon nanotubes, for example, 95% purity corresponds to C i =50000mg / L.C f: Target impurity concentration, determined according to product purity requirements, for example, 99.9% purity corresponds to C f =1000 mg / L. k: reaction rate constant, depends on the type and concentration of the acid, for example, for 3M sulfuric acid, k≈0.005 L / (mol·min·K). t: reaction time of a single reactor, usually set to 120-180 minutes. T: reaction temperature, generally in the range of 353-373 K. V: reactor volume, for example, 500 L.

[0031] This formula is based on the principle of chemical kinetics and assumes that impurity removal follows first-order reaction kinetics. In each reactor, the impurity concentration decays exponentially with time. The log(1+ktT / V) in the formula represents the impurity removal efficiency of a single reactor, where ktT / V represents the dimensionless degree of reaction. By taking the logarithmic ratio log(C i / C f ), the total degree of reaction required to achieve the target purity can be calculated. The total degree of reaction divided by the efficiency of a single reactor gives the number of reactors required.

[0032] For example, based on the experimental data in Table 1 (3M sulfuric acid, T = 363K, V = 500L), the fitting parameters can be obtained as follows: i =50000mg / L, C f =1000mg / L, k=0.005L / (mol·min·K), t=150min, T=363K, V=500L.

[0033] Table 1-3M sulfuric acid

[0034]

[0035]

[0036] , therefore, in this case, 4 reactors are required to achieve the target purity.

[0037] In an implementation scenario, 2-3 reactors are usually set up to meet most purification needs. The purpose of setting up multiple reactors is to perform multiple acid washes to gradually increase the purity of carbon nanotubes. The determination of the specific number of reactors depends on the following factors: 1) The initial purity of the raw carbon nanotubes. The lower the purity, the more acid washes are required. 2) The purity requirements of the target product. The higher the requirements, the more acid washes are required. 3) Production scale. The larger the scale, the more reactors can be considered to improve efficiency. 4) Economic considerations. The number of reactors needs to be weighed against investment costs and operating costs.

[0038] Taking a typical medium-scale production line as an example, three reactors can be set up for primary pickling, secondary pickling and final pickling. The volume of each reactor can be designed to be 500L, made of 316L stainless steel, lined with polytetrafluoroethylene (PTFE) to resist acid corrosion. The top of the reactor is equipped with a feed inlet, a discharge port, a stirring device and a temperature sensor. The bottom is equipped with a drain port.

[0039] The reactor is used to carry out the acid washing and purification reaction of carbon nanotubes. Under the acidic environment and heating conditions, the acid can dissolve or oxidize the metal catalyst residues, amorphous carbon and other impurities on the surface of the carbon nanotubes, thereby improving the purity of the carbon nanotubes.

[0040] At step S102, an independent electromagnetic heating pipeline is configured for each reactor, and the electromagnetic heating pipeline is used to heat and transport the acid liquid. The electromagnetic heating pipeline is not only used to heat the acid liquid, but also has the function of transporting the acid liquid. Compared with traditional heating methods, electromagnetic heating technology has the advantages of fast heating speed, high energy conversion efficiency, and precise temperature control. By applying electromagnetic heating technology in the pipeline, the acid liquid can be heated to the required temperature before entering the reactor, thereby improving the reaction efficiency and energy utilization.

[0041] Specifically, it includes: configuring an electromagnetic heating pipeline system, including an electromagnetic heater, a stainless steel coil, a PTFE lining, an insulation layer, a temperature sensor and a flow meter, wherein the electromagnetic heater adopts high-frequency electromagnetic induction heating; setting the inner diameter of the stainless steel coil to 20 mm, the wall thickness to 2 mm, and winding it into a spiral shape, coating the inner wall of the stainless steel pipe with a 1 mm thick PTFE layer, and wrapping the outside of the coil with a 50 mm thick glass wool insulation layer; installing a temperature sensor at the inlet and outlet of the coil, and installing an electromagnetic flowmeter at the inlet of the coil; controlling the outlet temperature of the acid solution by adjusting the flow rate and heating power to stabilize it within the set range.

[0042] In one embodiment, the electromagnetic heating pipeline system may be composed of, including but not limited to, the following parts: 1) Electromagnetic heater: using high-frequency electromagnetic induction heating technology, with adjustable power and a maximum power of 50kW. 2) Stainless steel coil: inner diameter 20mm, wall thickness 2mm, total length of approximately 30m, coiled into a spiral shape. 3) PTFE lining: a 1mm thick PTFE layer is coated on the inner wall of the stainless steel pipe to prevent acid corrosion. 4) Insulation layer: a 50mm thick glass wool insulation layer is wrapped around the outside of the coil to reduce heat loss. 5) Temperature sensor: a PT100 temperature sensor is installed at the inlet and outlet of the coil. 6) Flowmeter: an electromagnetic flowmeter is installed at the inlet of the coil to measure the acid flow.

[0043] The working principle of electromagnetic heating pipeline is to use high-frequency alternating magnetic field to generate eddy current in the metal pipe wall, which generates Joule heat to directly heat the pipe wall, and then heats the acid in the pipe through heat conduction. This heating method has the advantages of fast heating, precise temperature control and low energy consumption.

[0044] The flow of acid in the pipeline can be precisely controlled by adjusting the flow rate and heating power to ensure that the pickling reaction is carried out at the optimal temperature. Among them, the acid outlet temperature is controlled by adjusting the flow rate and heating power, including: Q1 = v·A·(T out -T in )·ρ·c p , where Q1 represents the heating power without waste heat recovery, v represents the flow rate, A represents the pipe cross-sectional area, and T out Indicates the outlet temperature, T in represents the inlet temperature, ρ represents the acid density, c p Represents the specific heat of acid.

[0045] In step S103, the carbon nanotube raw material is added to the first reactor, and the acid liquid is heated by the electromagnetic heating pipe to pickle the raw material. This step includes adding the carbon nanotube raw material to the first reactor, heating the acid liquid by the electromagnetic heating pipe, and then transporting the heated acid liquid to the reactor to pickle the raw material. In this process, the role of the electromagnetic heating pipe is fully utilized, ensuring that the acid liquid has reached the optimal reaction temperature when entering the reactor.

[0046] Specifically, the method comprises: mixing the acid components in a preselected acid formula in a predetermined volume ratio to prepare an acid solution, heating the acid solution to a predetermined temperature through an electromagnetic heating pipeline system; slowly adding a pre-weighed dry carbon nanotube raw material to the acid solution heated to the predetermined temperature, and stirring at a predetermined speed; continuously carrying out the pickling reaction at the predetermined temperature for a predetermined time, and intermittently sampling to detect changes in the impurity content; stopping heating and stirring, and after the reaction mixture is naturally cooled to a predetermined temperature, separating the solid from the liquid by a centrifuge; repeatedly washing the separated carbon nanotubes with deionized water until the pH value of the washing solution reaches a predetermined range; and vacuum drying the washed carbon nanotubes at a predetermined temperature for a predetermined time.

[0047] Taking the initial pickling of the first reactor as an example, the specific operation steps are as follows:

[0048] Preparation of acid solution: Select the appropriate acid solution formula according to the type of carbon nanotubes and the impurities. Commonly used acid solutions include sulfuric acid, nitric acid or a mixture of the two. For example, a mixture of concentrated sulfuric acid (98%) and concentrated nitric acid (65%) with a volume ratio of 3:1 can be used. The total volume of the acid solution should be 80% of the effective volume of the reactor, that is, 400L.

[0049] Preheating the acid solution: The prepared acid solution is heated to 70°C through the electromagnetic heating pipeline system. During the heating process, the flow rate is controlled at 20L / min, and the electromagnetic heater power is initially set to 40kW, which is then automatically adjusted according to the PID control algorithm.

[0050] Add carbon nanotubes: When the acid solution temperature is stable at 70°C, slowly add 50 kg of dry raw carbon nanotubes. Keep stirring during the addition process at a stirring speed of 100 rpm.

[0051] Reaction process: The reaction was continued at 70°C for 4 hours. During the reaction, the temperature was maintained constant by the electromagnetic heating pipeline system. Samples were taken every 30 minutes to monitor the changes in impurity content.

[0052] End of reaction: Stop heating and turn off stirring after 4 hours. Allow the reaction mixture to cool naturally to 50°C. It should be noted that the reason why the reaction mixture needs to be cooled naturally to 50°C before solid-liquid separation is that the strong acid solution at 70°C is highly corrosive and volatile, and cooling can reduce operational risks. Lower temperatures can also reduce thermal stress and corrosion on centrifugal separation equipment. In addition, lowering the temperature can help improve the efficiency of solid-liquid separation.

[0053] Separation: The reaction mixture was separated into solid and liquid by centrifugation. The speed of the centrifuge was set at 5000 rpm and the centrifugation time was 30 minutes.

[0054] Washing: The separated carbon nanotubes are repeatedly washed with deionized water until the pH value of the washing solution is close to neutral (pH 6-7).

[0055] Drying: The cleaned carbon nanotubes were dried in a vacuum drying oven at 60°C.

[0056] At step S104, the high-temperature waste liquid in the first reactor is collected, and the waste heat is recovered by using a heat exchanger to heat the fresh acid liquid in the heating pipe of the next reactor in combination with electromagnetic heating. After the first reactor completes pickling, the high-temperature waste liquid is collected. Although these waste liquids can no longer be used for pickling, they still have a high temperature and contain a large amount of thermal energy. In order to make full use of this part of thermal energy, the embodiment of the present application introduces a heat exchanger for waste heat recovery. Specifically, the high-temperature waste liquid is introduced into the heat exchanger to preheat the fresh acid liquid in the heating pipe of the next reactor. This method of waste heat recovery not only reduces energy waste, but also reduces the additional heating energy consumption required for the second pickling.

[0057] Specifically, the high-temperature waste liquid after pickling in the first reactor is discharged and collected in an insulation tank of a preset capacity; a heat exchanger made of a target material and having a predetermined heat exchange area and heat transfer coefficient is set in the heating system of the next reactor; a corrosion-resistant pump is used to transport the waste liquid from the insulation tank to the heat exchanger at a preset flow rate, and heat exchange is carried out with the low-temperature fresh acid liquid entering the next reactor, so that the waste liquid is cooled and the fresh acid liquid is heated; the preheated fresh acid liquid is further heated to the target temperature through the heating pipe system, and the waste liquid that has completed the heat exchange is transported to the waste liquid treatment system for neutralization treatment.

[0058] This step is the core point of the embodiment of this application, which realizes efficient utilization of energy by recovering waste heat from waste liquid. The specific implementation plan is as follows:

[0059] Waste liquid collection: After the first reactor is pickled, the waste liquid at about 50°C is discharged through the bottom drain port and collected in a 300L insulation tank.

[0060] Heat exchanger design: Add a plate heat exchanger to the electromagnetic heating piping system of the second reactor. The heat exchanger is made of 316L stainless steel and has a heat exchange area of ​​10m 2 , heat transfer coefficient is 2000W / (m 2 ·K).

[0061] Waste liquid pumping: Use a corrosion-resistant magnetic drive pump to pump the waste liquid from the insulation tank into the heat exchanger, and the flow rate is controlled at 15L / min.

[0062] Heat exchange process: The waste liquid exchanges heat with the fresh acid liquid that is about to enter the second reactor in the heat exchanger. The waste liquid is cooled from 50℃ to 30℃, while the fresh acid liquid is preheated from 20℃ to 27-33℃.

[0063] Temperature control: The fresh acid after heat exchange is heated to 70°C through the electromagnetic heating pipeline system. Due to preheating, the required additional heating power will be reduced.

[0064] Waste liquid treatment: The waste liquid after heat exchange is sent to the waste liquid treatment system for neutralization and treatment.

[0065] The heat transfer in the heat exchange process can be described by the following formula: Q = U*A*LMTD, where Q is the heat transfer amount (W) and U is the total heat transfer coefficient (W / (m 2 ·K)), A is the heat exchange area (m 2), LMTD is the logarithmic mean temperature difference (K). LMTD = ((T_h1-T_c2)-(T_h2-T_c1)) / ln((T_h1-T_c2) / (T_h2-T_c1)), where T_h1 and T_h2 are the inlet and outlet temperatures of the hot fluid (waste liquid), and T_c1 and T_c2 are the inlet and outlet temperatures of the cold fluid (fresh acid liquid). Through this heat source secondary utilization scheme, the heating energy consumption required for the second pickling can be significantly reduced, and the energy efficiency of the entire purification process can be improved.

[0066] Therefore, the preheated fresh acid solution is further heated to the target temperature through the heating pipe system, including: Q2 = Q1-U·B·LMTD, where Q2 represents the heating power after waste heat recovery, Q1 represents the heating power without waste heat recovery, U represents the total heat transfer coefficient, B represents the heat exchange area, and LMTD represents the logarithmic mean temperature difference.

[0067] At step S105, the acid solution recovered from the waste heat is used to pickle the raw material in the next reactor, and the waste heat recovery, heating and pickling process are repeated until the raw material is finally pickled by the final reactor to obtain purified carbon nanotubes. This step makes full use of the waste heat of the first pickling waste liquid, which not only improves the energy utilization efficiency, but also ensures the reaction temperature of the second pickling. It is worth noting that this waste heat recovery and pickling process can be repeated as many times as needed until the raw material is finally pickled by the final reactor to obtain a high-purity carbon nanotube product.

[0068] The process includes: transferring the carbon nanotubes after the initial pickling to the next-stage reactor, adding newly prepared acid solution with waste heat recovery for secondary pickling; repeating the pickling and waste heat recovery of the waste liquid until the product is transferred to the final reactor, and performing the final pickling with a low-concentration acid solution; rinsing the carbon nanotubes with deionized water until the pH value is neutral, grinding the dried carbon nanotubes with a ball mill, and sieving with a sieve with a preset mesh size to remove large particle impurities to obtain purified carbon nanotubes.

[0069] In one implementation scenario, the carbon nanotubes after the first acid washing are transferred to the second reactor, and newly prepared acid solution is added (the acid solution concentration can be adjusted according to the result of the first acid washing). The acid washing process in the third step is repeated, but the reaction time can be shortened to 3 hours.

[0070] If desired, a final acid wash can be performed in the third reactor, this time using a milder acid such as 1M hydrochloric acid for 2 hours.

[0071] After the last acid wash, the carbon nanotubes are rinsed with a large amount of deionized water until the pH value is close to 7. The pH value of the washing solution can be monitored in real time using a pH meter.

[0072] If it is necessary to further improve the dispersibility of carbon nanotubes or add specific functional groups, functionalization treatment can be performed at this stage. For example, hydroxyl and carboxyl groups can be introduced by treating with H2O2 solution at 60°C for 2 hours.

[0073] The treated carbon nanotubes were dried in a vacuum drying oven at 80°C for 24 hours to ensure complete drying.

[0074] Use a ball mill to lightly grind the dried carbon nanotubes to break up the agglomerates. Ball milling parameters: ball-to-material ratio 10:1, speed 200rpm, time 30 minutes. Use a 100-mesh screen to sieve to remove any large particles of impurities. Put the final product into an anti-static, moisture-proof aluminum foil bag and vacuum seal it for storage.

[0075] At step S106, multiple groups of pickling data are collected, and the target configuration number of reactors is determined based on the purity curve and energy efficiency curve of carbon nanotubes with different pickling times. The method includes: collecting multiple groups of carbon nanotube samples, and performing pickling treatment on each group of samples for different times, wherein the pickling times vary within a preset range; measuring the purity, treatment quality, actual energy consumption and waste heat recovery of carbon nanotubes for each sample after pickling, and recording the pickling operation parameters; fitting the parameters of the purity prediction model using a nonlinear regression method, and drawing a curve of the change of carbon nanotube purity with the pickling times; calculating the energy utilization efficiency of each group of experiments, and drawing a curve of the change of energy efficiency with the pickling times; constructing a comprehensive performance index, combining the purity improvement function with the energy efficiency function, and setting a weight coefficient to determine the relative importance of purity and energy efficiency; calculating the corresponding comprehensive performance index value for each pickling time within the preset range; checking whether the purity requirements and the minimum energy efficiency constraints are met; and selecting the value that maximizes the comprehensive performance index as the optimal pickling times and the target configuration number of reactors among the pickling times that meet the constraints.

[0076] Further, a comprehensive performance index is constructed, combining the purity improvement function with the energy efficiency function, and setting weight coefficients to determine the relative importance of purity and energy efficiency, including: Where J(n) represents the comprehensive performance index of pickling times n, w1 and w2 represent weight coefficients, f(P(n)) represents the purity improvement function, g(η(n)) represents the energy efficiency function, P(n) represents the purity of pickling times n, P initial represents the initial purity, P0 represents the theoretical maximum purity, η(n) represents the energy efficiency of pickling times n, η max represents the maximum energy efficiency observed in the experiment.

[0077] Specifically, in order to determine the optimal configuration number of the reactor (i.e. the optimal number of pickling times), it is necessary to collect multiple sets of pickling data and draw the carbon nanotube purity curve and energy efficiency curve based on these data. The specific steps are as follows: prepare multiple batches of carbon nanotube samples, and perform pickling treatments on each batch of samples for different times, ranging from 1 to 6 times. After each pickling, measure the following parameters: carbon nanotube purity (P), mass of carbon nanotubes treated (m), total energy actually consumed (E_total), energy saved through waste heat recovery (E_recovered), and record the operating parameters of each pickling, such as acid concentration, temperature, time, etc. Repeat the experiment many times to ensure the reliability and consistency of the data, and remove abnormal values ​​and outliers.

[0078] The purity prediction model shown below can be used (eg Figure 2 As shown in the figure, the purity data is analyzed as follows: P_final = P_0-(P_0-P_initial)*e^(-k*n), where P_final: final purity (%), P_0: theoretical maximum purity (%), P_initial: initial purity (%), k: purification efficiency coefficient of each acid wash, and n: number of acid washes.

[0079] Using the experimental data, the best fitting values ​​of the parameters P_0 and k were determined by nonlinear regression method. Using the determined parameters, a curve of purity changing with the number of acid washings was plotted.

[0080] The energy efficiency can then be used as shown below ( Figure 3 The energy efficiency data is analyzed by using the calculation formula (as shown): η=(m*ΔH) / (E_total-E_recovered), where η is the energy utilization efficiency, m is the mass of carbon nanotubes treated (kg), ΔH is the theoretical energy required for purifying unit mass of carbon nanotubes (kJ / kg), E_total is the total energy actually consumed (kJ), and E_recovered is the energy saved by waste heat recovery (kJ).

[0081] Calculate the energy efficiency η for each set of experimental data and draw a curve showing the energy efficiency η changing with the number of pickling times.

[0082] In order to determine the optimal number of pickling times, two factors need to be considered: purity improvement and energy efficiency. A comprehensive optimization model can be constructed to combine these two factors. By defining a comprehensive performance index J, it is expressed as a function of purity improvement and energy efficiency: J(n) = w_1*f(P(n)) + w_2*g(η(n)), where: J(n): comprehensive performance index, n: number of pickling times, w_1, w_2: weight coefficients, reflecting the relative importance of purity and energy efficiency, f(P(n)): purity improvement function, g(η(n)): energy efficiency function. Specifically, it can be defined as: f(P(n)) = (P(n)-P_initial) / (P_0-P_initial), g(η(n)) = η(n) / η_max, where η_max is the maximum energy efficiency observed in all experiments.

[0083] In one embodiment, the purity constraint is: P(n)≥P_required, where P_required is the minimum required purity. The energy efficiency constraint is: η(n)≥η_min, where η_min is the minimum acceptable energy efficiency.

[0084] Integer constraint: n is a positive integer.

[0085] Since the number of pickling times n is discrete, enumeration or dynamic programming can be used to solve the optimal n value: for each possible n value (from 1 to the maximum allowed number of pickling times), calculate J(n). Check whether all constraints are met. Among the n that meet the constraints, select the n value that maximizes J(n) as the optimal number of pickling times.

[0086] First, the parameters of the purity prediction model are fitted using experimental data: P(n) = P_0-(P_0-P_initial)*e^(-k*n), and the values ​​of P_0 and k are estimated using nonlinear least squares. For each number of pickling times n, the corresponding energy efficiency η(n) is calculated: η(n) = (m*ΔH) / (E_total(n)-E_recovered(n)), where E_total(n) and E_recovered(n) are the actual energy consumption and recovery after n pickling times. Determine the weight coefficients w_1 and w_2. This can be set according to product requirements and production cost considerations, for example, w_1 = 0.6, w_2 = 0.4. For each possible value of n (for example, from 1 to 6), the comprehensive performance index J(n) is calculated: J(n) = w_1*((P(n)-P_initial) / (P_0-P_initial))+w_2*(η(n) / η_max). Check the constraints: P(n) ≥ P_required, η(n) ≥ η_min. Only consider values ​​of n that satisfy these constraints, and among the values ​​of n that satisfy the constraints, choose the n that maximizes J(n) as the optimal number of pickling times.

[0087] For example, the following experimental data: P_initial = 80%, P_required = 95%, η_min = 0.5, through data fitting, we can get: P_0 = 99.9%, k = 0.8, for n = 1 to 5, calculate:

[0088] n=1: P(1)=95.98%, η(1)=0.60

[0089] n=2: P(2)=98.72%, η(2)=0.65

[0090] n=3: P(3)=99.52%, η(3)=0.68

[0091] n=4: P(4)=99.79%, η(4)=0.70

[0092] n=5: P(5)=99.89%, η(5)=0.71

[0093] Assume η_max = 0.71, w_1 = 0.6, w_2 = 0.4, and calculate J(n):

[0094] J(1)=0.6*(0.7990 / 0.999)+0.4*(0.60 / 0.71)=0.6784

[0095] J(2)=0.6*(0.9360 / 0.999)+0.4*(0.65 / 0.71)=0.7975

[0096] J(3)=0.6*(0.9760 / 0.999)+0.4*(0.68 / 0.71)=0.8457

[0097] J(4)=0.6*(0.9895 / 0.999)+0.4*(0.70 / 0.71)=0.8684

[0098] J(5)=0.6*(0.9945 / 0.999)+0.4*(0.71 / 0.71)=0.8768

[0099] All n values ​​satisfy the constraint. J(n) reaches its maximum value when n=5, so the optimal number of pickling times is 5. In addition, when n is less than 2, the optimal number of pickling times is 2.

[0100] This method can be used to determine the optimal number of pickling times based on actual experimental data, taking into account purity improvement and energy efficiency. This method takes into account the two key factors of purity and energy efficiency and is able to strike a balance between the two. By adjusting the weight coefficient, it can flexibly adapt to different production strategies and market demands.

[0101] Finally, it should be emphasized that the accuracy and effectiveness of this model largely depends on the quality and quantity of experimental data. Therefore, in practical applications, a large number of experiments and data collection should be carried out, and the model parameters should be updated regularly to ensure that the model can accurately reflect the actual situation of the production process.

[0102] Figure 2 A schematic diagram of a purity curve provided in the embodiment of the present application. Figure 2 As shown in the figure, the purity curve shows a typical exponential growth shape, which is consistent with the mathematical form of the model. The purity increases rapidly in the initial stage (the first few acid washes), and then the growth rate gradually slows down, and finally approaches the theoretical maximum purity P_0. This trend reflects the common situation in the purification process: the initial purification effect is significant, but as the purity increases, further improvement becomes increasingly difficult.

[0103] Figure 3 A schematic diagram of an energy efficiency curve provided in an embodiment of the present application. For the energy efficiency curve, the embodiment of the present application draws three lines: a) electromagnetic heating (with waste heat recovery): using a circular mark ('-o'), b) electromagnetic heating (without waste heat recovery): using a cross mark ('-x'), c) direct pickling: using a square mark ('-s'). Figure 3 As shown in the figure, electromagnetic heating (with waste heat recovery) has the highest energy efficiency, because the waste heat recovery system can reduce energy loss. The energy efficiency of electromagnetic heating (without waste heat recovery) is second, but still higher than the direct pickling method. This may be due to the high energy conversion efficiency of electromagnetic heating. Direct pickling has the lowest energy efficiency, which may be due to the large heat loss and the lack of a waste heat recovery system. All curves show that the energy efficiency increases with the increase in the number of pickling times. This may be because the subsequent pickling process can utilize the waste heat of the previous process, or the operating parameters have been optimized.

[0104] Comparing the purity curve and the energy efficiency curve, it can be obtained that: in the initial stage, the purity increases rapidly, while the energy efficiency is relatively low. This may be because a large amount of impurities need to be removed in the initial stage, and the energy consumption is large. As the number of pickling times increases, the purity improvement rate slows down, but the energy efficiency continues to improve. This may be because in the subsequent pickling process, fewer impurities need to be removed, and energy can be more effectively used to remove target impurities. This relationship proves that in actual production, the method described in the previous embodiment can be used to find a balance between purity and energy efficiency.

[0105] In general, the high-efficiency carbon nanotube purification method based on electromagnetic heating and waste heat recovery provided in this embodiment significantly improves the energy utilization efficiency of the purification process through the heating method and energy recovery technology, and optimizes the number of reactors, that is, the number of acid washing times. This method not only improves the purity of carbon nanotubes, but also reduces production costs and energy consumption, and has good economic and environmental benefits.

[0106] Figure 4 A schematic block diagram of an efficient purification device for carbon nanotubes based on electromagnetic heating and waste heat recovery provided in an embodiment of the present application. It should be understood that the device shown in the figure is exemplary and not restrictive. This means that the system architecture involved is not limited to a specific form or design, but is presented as an example. In other words, the architecture shown in the figure can be regarded as a way of expression to clearly describe related concepts and relationships, and does not exclude other forms of architecture. Therefore, when interpreting the architecture in the picture, it should be understood that the model is flexible and diverse, and its purpose is to provide an exemplary description rather than a restrictive provision on a specific form.

[0107] The present application discloses a carbon nanotube high-efficiency purification device based on electromagnetic heating and waste heat recovery, which applies the high-efficiency purification method described in any of the above embodiments, and comprises: at least two reactors, one or more electromagnetic heating pipes and a heat exchanger; wherein the reactor is provided with a feed port, a discharge port, a liquid discharge port, a stirring device and / or a temperature sensor; each reactor is equipped with an independent electromagnetic heating pipe; the electromagnetic heating pipe is used for heating and transporting acid liquid; the heat exchanger is used for recovering waste heat to heat the fresh acid liquid in the heating pipe of the target reactor.

[0108] It should be understood that the technical solution of the present application is not limited to the above steps, and can also be flexibly adjusted and optimized according to actual production needs. For example, the number of reactors, the number of acid washings, the reaction temperature and other parameters can be adjusted according to the characteristics of the carbon nanotube raw materials and the purification requirements. In addition, an automatic control device can be added to the system to realize the intelligent management of the entire purification process, further improving the production efficiency and the stability of product quality.

[0109] The technical solution of the present application has many advantages. First, by setting up multiple reactors and utilizing electromagnetic heating technology, the pickling process is carried out efficiently. The application of electromagnetic heating technology not only improves the heating efficiency, but also realizes the precise control of the reaction temperature, which is beneficial to improving the consistency of product quality. Secondly, through the waste heat recovery system, the thermal energy in the waste liquid is fully utilized, which significantly reduces energy consumption and production costs. This recycling method not only has significant economic benefits, but also has good environmental protection effects. Furthermore, the design of the entire system fully considers the continuity and automation of the process, which is conducive to improving production efficiency and reducing manual operation costs.

[0110] In addition, the technical solution of the present application also has good scalability and adaptability. For example, the number and capacity of the reactors can be adjusted according to the actual production scale; the number of acid washing times and reaction conditions can be adjusted according to the purification requirements of different types of carbon nanotubes; the technical solution can also be combined with other purification technologies, such as ultrasound-assisted purification, microwave-assisted purification, etc., to further improve the purification effect and efficiency.

[0111] In general, the method and device for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery provided by this application effectively solve the problems of energy waste and high cost in the traditional carbon nanotube purification process through process design and equipment configuration. This method not only improves the efficiency and quality of carbon nanotube purification, but also realizes efficient utilization of energy, with significant economic and environmental benefits. The application of this technical solution will help promote the sustainable development of the carbon nanotube industry and provide new ideas and directions for technological progress in related fields.

[0112] Furthermore, an embodiment of the present application also provides a high-efficiency purification device for carbon nanotubes based on electromagnetic heating and waste heat recovery, including: a processor, a memory, and a system bus; the processor and the memory are connected via the system bus; the memory is used to store one or more programs, and the one or more programs include instructions, which, when executed by the processor, enable the processor to execute any of the above methods.

[0113] Furthermore, an embodiment of the present application also provides a computer program product, which, when executed on a terminal device, enables the terminal device to execute any of the above methods.

[0114] It can be known from the description of the above implementation mode that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., including several instructions for enabling a computer device (which can be a personal computer, a server, or a network communication device such as a media gateway, etc.) to execute the methods described in the various embodiments of the present application or certain parts of the embodiments.

[0115] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0116] It should also be noted that, in the embodiments of the present application, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements that are not clearly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements limited by the statement "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment including the elements.

[0117] The above description of the disclosed embodiments enables professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, and the general principles defined in the embodiments of the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the embodiments of the present application, but will conform to the widest range consistent with the principles and novel features disclosed in the embodiments of the present application.

Claims

1. A method for efficiently purifying carbon nanotubes based on electromagnetic heating and waste heat recovery, characterized in that: include: At least two reaction kettles for pickling are provided, wherein the reaction kettles are provided with a feed inlet, a discharge outlet, a liquid discharge outlet, a stirring device and / or a temperature sensor; Each reactor is equipped with an independent electromagnetic heating pipeline, which is used to heat and transport the acid solution; Adding carbon nanotube raw materials into the first reaction kettle, and heating the acid solution by using an electromagnetic heating pipe to acid-wash the raw materials; The high-temperature waste liquid in the first reactor is collected and the waste heat is recovered by using a heat exchanger, so as to heat the fresh acid liquid in the heating pipe of the next reactor in combination with electromagnetic heating; In the next stage reactor, the raw material is pickled with acid liquid recovered from waste heat, and the waste heat recovery, heating and pickling process are repeated until the raw material is finally pickled by the final reactor to obtain purified carbon nanotubes; Multiple sets of pickling data were collected, and the purity curves and energy efficiency curves of carbon nanotubes with different pickling times were constructed to optimize the number of reactors to be set.

2. The method for efficiently purifying carbon nanotubes according to claim 1, characterized in that: in, Each reactor is equipped with an independent electromagnetic heating pipeline, which is used to heat and transport the acid solution, including: Configure electromagnetic heating pipeline system, including electromagnetic heater, stainless steel coil, PTFE lining, insulation layer, temperature sensor and flow meter, where the electromagnetic heater adopts high-frequency electromagnetic induction heating; The inner diameter of the stainless steel coil is set to 20 mm, the wall thickness is set to 2 mm, and it is coiled into a spiral shape. A 1 mm thick PTFE layer is coated on the inner wall of the stainless steel tube, and a 50 mm thick glass wool insulation layer is wrapped around the outside of the coil. Install a temperature sensor at the inlet and outlet of the coil, and install an electromagnetic flowmeter at the inlet of the coil; By adjusting the flow rate and heating power, the acid liquid outlet temperature is controlled to be stable within the set range.

3. The method for efficiently purifying carbon nanotubes according to claim 1, characterized in that: in, Adding carbon nanotube raw materials into a first reaction kettle and heating acid solution by using an electromagnetic heating pipe to acid wash the raw materials, including: The acid solution prepared by mixing the acid components in the pre-selected acid solution formula according to a predetermined volume ratio is heated to a predetermined temperature through an electromagnetic heating pipeline system; Slowly adding a pre-weighed amount of dry carbon nanotube raw material into the acid solution heated to a predetermined temperature, and stirring at a predetermined speed; Continue to carry out the pickling reaction at the predetermined temperature for a predetermined time, and intermittently take samples to detect changes in impurity content; Stop heating and stirring, wait for the reaction mixture to cool naturally to a predetermined temperature, and then separate the solid from the liquid by a centrifuge; Repeatedly washing the separated carbon nanotubes with deionized water until the pH value of the washing solution reaches a predetermined range; The cleaned carbon nanotubes are vacuum dried at a predetermined temperature for a predetermined time.

4. The method for efficiently purifying carbon nanotubes according to claim 1, characterized in that: in, The high-temperature waste liquid in the first reactor is collected and the waste heat is recovered by using a heat exchanger, so as to heat the fresh acid liquid in the heating pipe of the next reactor in combination with electromagnetic heating, including: The high-temperature waste liquid after pickling in the first reactor is discharged and collected into a heat preservation tank with a preset capacity; A heat exchanger of target material, with a predetermined heat exchange area and heat transfer coefficient is provided in the heating system of the next-stage reactor; The waste liquid is transported from the insulation tank to the heat exchanger at a preset flow rate using a corrosion-resistant pump, and heat is exchanged with the low-temperature fresh acid entering the next-stage reactor, so that the waste liquid is cooled and the fresh acid is heated; The preheated fresh acid liquid is further heated to the target temperature through the heating pipe system, and the waste liquid after the heat exchange is transported to the waste liquid treatment system for neutralization treatment.

5. The method for efficiently purifying carbon nanotubes according to claim 1, characterized in that: in, The raw material is pickled using acid liquid recovered from waste heat in the next stage reactor, and the waste heat recovery, heating and pickling process are repeated until the raw material is finally pickled by the final stage reactor to obtain purified carbon nanotubes, including: The carbon nanotubes after the initial pickling are transferred to the next-stage reactor, and the newly prepared acid solution after waste heat recovery and electromagnetic heating is added for secondary pickling; Repeat pickling, waste heat recovery and electromagnetic heating of waste liquid until the product is transferred to the final reactor and finally pickled with low-concentration acid solution; The carbon nanotubes are rinsed with deionized water until the pH value is neutral, and the dried carbon nanotubes are ground with a ball mill, and sieved with a sieve with a preset mesh number to remove large particle impurities to obtain purified carbon nanotubes.

6. The method for efficiently purifying carbon nanotubes according to claim 1, characterized in that: in, Collect multiple sets of pickling data and construct carbon nanotube purity curves and energy efficiency curves for different pickling times to optimize the number of reactor settings, including: Collecting multiple groups of carbon nanotube samples, and performing different times of acid washing on each group of samples, wherein the number of acid washings varies within a preset range; The purity, treatment quality, actual energy consumption and waste heat recovery of carbon nanotubes were measured for each sample after pickling, and the pickling operation parameters were recorded; The nonlinear regression method was used to fit the parameters of the purity prediction model, and the curve of the change of carbon nanotube purity with the number of acid washings was plotted; the energy utilization efficiency of each group of experiments was calculated, and the curve of the change of energy efficiency with the number of acid washings was plotted; Construct a comprehensive performance index that combines the purity improvement function with the energy efficiency function, and set weight coefficients to determine the relative importance of purity and energy efficiency; For each pickling number within the preset range, calculate the corresponding comprehensive performance index value; check whether the purity requirements and the minimum energy efficiency constraints are met; among the pickling times that meet the constraints, select the value that maximizes the comprehensive performance index as the optimal pickling number and the target configuration number of reactors.

7. The method for efficiently purifying carbon nanotubes according to claim 6, characterized in that: in, Construct a comprehensive performance index that combines the purity improvement function with the energy efficiency function, and set weight coefficients to determine the relative importance of purity and energy efficiency, including: Where J(n) represents the comprehensive performance index of pickling times n, w1 and w2 represent weight coefficients, f(P(n)) represents the purity improvement function, g(η(n)) represents the energy efficiency function, P(n) represents the purity of pickling times n, P initial represents the initial purity, P0 represents the theoretical maximum purity, η(n) represents the energy efficiency of pickling times n, η max represents the maximum energy efficiency observed in the experiment.

8. A carbon nanotube efficient purification device based on electromagnetic heating and waste heat recovery, used to implement the carbon nanotube efficient purification method according to any one of claims 1 to 7, characterized in that: include: At least two reactors, one or more electromagnetic heating pipes and a heat exchanger; wherein, The reactor is provided with a feed inlet, a discharge outlet, a liquid discharge outlet, a stirring device and / or a temperature sensor; each reactor is equipped with an independent electromagnetic heating pipeline; The electromagnetic heating pipeline is used to heat and transport the acid liquid; The heat exchanger is used to recover waste heat to heat the fresh acid solution in the heating pipe of the target reactor.

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