Mobile internal heat source coordinated driving and circulating electromagnetic induction pyrolysis device and method
By using a recyclable ferromagnetic heat transfer medium and electromagnetic induction technology in a rotary kiln, efficient heat transfer from the inside out and uniform heating are achieved, solving the problems of low heat transfer efficiency and uneven temperature in traditional rotary kilns, and improving the quality of pyrolysis products and the stability of the device.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG FORESTRY UNIVERSITY
- Filing Date
- 2026-04-28
- Publication Date
- 2026-06-12
AI Technical Summary
Existing rotary kiln pyrolysis technology suffers from problems such as low heat transfer efficiency, uneven temperature distribution, high energy consumption, and high equipment complexity. In particular, in electromagnetically heated rotary kilns, the radial temperature gradient caused by the heat source being fixed on the kiln wall is inconsistent with the degree of material pyrolysis, making it difficult to achieve efficient heat transfer and uniform heating.
A recyclable ferromagnetic heat transfer medium is used as a mobile internal heat source. It is heated and driven by electromagnetic induction technology, so that heat is released directly from the inside of the material. Combined with the traveling wave magnetic field driving the heat transfer medium to move radially and axially in the rotary kiln, a three-dimensional spiral propulsion motion is formed to achieve efficient heat transfer and uniform heating.
It achieves uniform temperature distribution within the kiln, improves the uniformity and quality stability of pyrolysis products, reduces energy consumption, and ensures continuous and stable operation of the device through closed-loop recycling of the heat transfer medium.
Smart Images
Figure CN122188683A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic solid waste pyrolysis technology, specifically to a rotary kiln pyrolysis device and method based on the principle of electromagnetic induction to achieve synchronous heating and driving of the heat transfer medium and to be recyclable. It can be used to efficiently convert carbon-containing organic solid wastes such as waste plastics, biomass, and waste tires into products such as pyrolysis oil, syngas, and / or carbon-containing solid materials. Background Technology
[0002] Waste plastics, waste tires, and agricultural and forestry biomass account for over 80% of organic solid waste. The disorderly accumulation and improper treatment of this carbon- and hydrogen-rich organic solid waste have triggered a chain of environmental problems, including leachate pollution, microplastic pollution, pathogen transmission, and soil degradation. Landfill disposal not only occupies land resources, but the methane gas produced during its anaerobic degradation process significantly exacerbates the greenhouse effect. While waste incineration can achieve a volume reduction rate of over 90% and recover heat energy, fluctuations in furnace temperature can induce the formation and release of persistent organic pollutants such as dioxins, causing secondary environmental pollution. Furthermore, the leaching concentration of heavy metals such as cadmium and lead in incineration fly ash exceeds the limits specified in the "Identification Standard for Hazardous Waste GB5805.3-2002" by 15-20 times. Therefore, developing clean and green, efficient technologies for the treatment of organic solid waste has become an urgent issue for the global energy and environmental engineering field.
[0003] Pyrolysis, due to its low carbon emissions, low pollution, and high energy recovery rate, is considered a key green technology for effectively achieving the harmless, resource-based, and high-value-added treatment of organic solid waste. In an anaerobic environment, high temperatures (350-750℃) break down and recombine macromolecules in organic components into pyrolysis oil, syngas, or carbon-based materials, which can replace fossil fuels such as petroleum and natural gas while significantly reducing carbon dioxide emissions. For example, waste plastic pyrolysis oil can be directly used as a refinery feedstock to replace crude oil, biomass pyrolysis gas can be used for power generation in gas turbines or fuel cells, and para-cymene can be recovered from waste tire pyrolysis products for the synthesis of chemical raw materials. Simultaneously, the anaerobic conditions of the pyrolysis process effectively inhibit the formation of persistent organic pollutants such as dioxins, thereby reducing secondary environmental risks.
[0004] The pyrolysis reactor is the core equipment of pyrolysis technology, and its performance directly determines the product yield, energy consumption, and process economy. Currently, mainstream reactors include fixed-bed, moving-bed, fluidized-bed, and rotary kilns. Among them, the rotary kiln is widely used for processing complex materials such as waste plastics, waste tires, and biomass due to its simple structure, wide material adaptability, and strong continuous processing capacity. However, traditional rotary kiln pyrolysis technology mostly uses external heating, that is, indirectly heating the kiln body through resistance wires or combustion chambers on the outer wall of the kiln, and then transferring heat to the material through the kiln wall. This heat transfer mode has drawbacks such as low heat transfer efficiency, high energy consumption, uneven temperature distribution, and unstable product quality.
[0005] To improve heat transfer, existing technologies have proposed a variety of improvement methods.
[0006] For example, patent document CN111550800B reports the installation of an internal enhanced heat exchange device along the centerline of the rotary kiln body. This heat exchange device consists of a flue gas inlet pipe, an outlet pipe, and a heat carrier circulation device. This patent increases the heat exchange efficiency inside the kiln, resulting in more complete pyrolysis. However, the device still primarily uses an external heat source, and the internal heat exchange device makes the rotary kiln structure more complex.
[0007] For example, patent document CN118909655B reports the installation of evenly distributed lifting plates on the inner wall of a rotary kiln to optimize the mixing of biomass pellets and high-temperature smelting slag, thereby improving the heat transfer efficiency within the reactor. The heat transfer method reported in this patent is similar to that of solid heat carrier pyrolysis. Although it changes the traditional external heating method to an internal heating method to some extent, it still requires premixing high-temperature smelting slag or circulating a solid heat carrier, resulting in higher operational complexity and difficulty in maintaining stable reaction temperature control.
[0008] In recent years, electromagnetic heating technology has been introduced into rotary kilns to improve heat transfer due to its high efficiency, cleanliness, and good controllability. Patent application CN202510651991.8 discloses a variable diameter electromagnetic heating rotary kiln system, which uses a traveling wave magnetic field in conjunction with an L-shaped ferromagnetic lifting plate to improve the temperature distribution inside the kiln. However, a deeper analysis of its technical solution reveals that the device still has fundamental heat transfer defects: (1) The heat source of the device is the kiln wall itself (the eddy currents generated in the kiln wall shell through electromagnetic induction to generate heat), and the heat must pass through the kiln wall-gas-material conduction path in sequence, which can essentially be classified as external heating. Since there is an air gap between the kiln wall and the material, and the material itself is a poor conductor of heat, this indirect conduction mode leads to low heat transfer efficiency and serious heat loss. (2) The heat source is always fixed at the kiln wall position, resulting in a significant radial temperature gradient inside the kiln - the material near the kiln wall is overheated, while the material in the center of the kiln heats up slowly, forming a cold core. This uneven temperature field causes uneven pyrolysis of materials, reduces the yield of the target product, and easily leads to local coking problems. Even if the traveling wave magnetic field is used to drive the lifting plate, the movement of the lifting plate is still limited to the near wall area and cannot effectively transfer heat to the core of the material bed. (3) The lifting plate of this device is fixed to the kiln wall, and its movement depends entirely on the passive rotation of the kiln body. It can only perform macroscopic and periodic tumbling of the material. This passive stirring method cannot penetrate the interior of the material accumulation layer and is difficult to achieve uniform mixing at the microscale. (4) Due to the fixed installation of the lifting plate, this device cannot achieve the separation and recycling of the heat carrier. After long-term operation, there are problems of heat carrier demagnetization and performance degradation after wear.
[0009] In summary, while existing technologies have made some progress in electromagnetically heated rotary kilns, they still fail to address the fundamental shortcomings of externally heated heat transfer modes, making it difficult to achieve a synergistic balance between efficient heat transfer, uniform heating, and equipment simplification. Therefore, developing a novel pyrolysis reaction device capable of releasing heat from the inside out, with a movable heat source and a recyclable medium is of great significance for overcoming the technological bottlenecks in the resource utilization of organic solid waste. Summary of the Invention
[0010] To address the aforementioned technical problems and shortcomings in the field, this invention provides a mobile internal heat source synergistic drive and circulation electromagnetic induction pyrolysis device and method. Its core concept is to use a recyclable ferromagnetic heat transfer medium as a mobile internal heat source, and simultaneously heat and drive it through electromagnetic induction technology, so that heat is released directly from the inside of the material, completely changing the heat transfer path from the outside to the inside of the traditional pyrolysis device.
[0011] The specific technical solution is as follows: In a first aspect, the present invention provides a mobile electromagnetic induction pyrolysis device with coordinated internal heat source drive and circulation, including a control system, an electromagnetic induction system, a circulation system, a ferromagnetic heat transfer medium, and a rotary kiln body with good magnetic field penetration; the rotary kiln body includes a feed end for receiving materials and a discharge end for discharging pyrolysis products. The electromagnetic induction system includes multiple sets of electromagnetic coils arranged around the outer wall of the rotary kiln and independently controlled by the control system in segments along the axial direction of the rotary kiln. The electromagnetic coils are used to pass in high-frequency alternating current to generate an alternating magnetic field, thereby magnetizing the heat transfer medium inside the rotary kiln and generating heat on its own to promote the pyrolysis of the material. The control system is used to regulate the current phase (difference) and timing of adjacent electromagnetic coils (groups) (e.g., using a control strategy with a 120° phase difference of three-phase AC power) to construct a controllable traveling wave magnetic field along the axial direction in the rotary kiln body, thereby driving the magnetized heat transfer medium to carry the material together in radial and / or axial motion within the rotary kiln body (e.g., moving from the feed end to the discharge end, moving from the discharge end to the feed end, reciprocating motion, etc.). The circulation system is used to receive the heat transfer medium discharged from the discharge end and reintroduce it into the rotary kiln body from the feed end.
[0012] The basic function of a rotary kiln is to realize the macroscopic axial conveying of materials such as carbon-containing organic solid waste (such as waste plastics, biomass, waste tires, etc.) from the feed end to the discharge end, and to achieve the initial tumbling and axial conveying of materials through the lifting-falling effect generated by the rotation of the kiln.
[0013] In some preferred embodiments, the walls of the rotary kiln body are non-magnetic.
[0014] In some preferred embodiments, the rotary kiln body is made of a material that is resistant to high temperatures and has good magnetic field penetration, such as non-magnetic austenitic stainless steel (e.g., 310S, 316L) and / or lined with high-purity alumina, silicon carbide and other ceramic materials in a conventional alloy steel shell, in order to reduce shielding and loss of alternating magnetic fields.
[0015] In some preferred embodiments, the rotary kiln body is installed at an angle with the feed end higher than the discharge end. Furthermore, the angle of inclination is preferably 1°-5°, such as 2°, 3°, 4°, etc.
[0016] In some preferred embodiments, the mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device further includes an air intake system; the air intake system is connected to the feed end and is used to introduce gas into the rotary kiln body. Further, the gas preferably includes an inert gas. In this invention, an inert gas refers to a gas that does not participate in the pyrolysis reaction, such as nitrogen. When necessary, the air intake system can introduce an inert gas (such as nitrogen) into the kiln body to ensure an oxygen-free or oxygen-deficient environment during the pyrolysis process.
[0017] The circulation system solves the problem of heat transfer medium recycling, which is currently impossible with existing technologies, ensuring the stability of the equipment's long-term continuous operation. Through the circulation system, the heat transfer medium completes its heating, heat transfer, and mixing functions within the kiln, and is then discharged from the kiln along with the pyrolysis products. After separation, it is returned to the feed end, achieving closed-loop recycling. This design not only solves the problem of heat transfer medium accumulating at the discharge port due to unidirectional movement within the kiln, but also ensures that newly fed materials always have sufficient contact with the high-temperature heat transfer medium, guaranteeing the continuity and stability of the process.
[0018] In some preferred embodiments, the circulation system includes a magnetic separator, a media replenishment and storage bin, and a conveying system.
[0019] The magnetic separator is connected to the discharge end and is used to magnetically separate the heat transfer medium and solid products (such as carbon black, residue, etc.).
[0020] The media replenishment and storage bin connects to the magnetic separator and the feed end, and is used to receive and store the heat transfer medium separated by magnetic separation, as well as to supply heat transfer medium to the feed end. The media replenishment and storage bin can replenish new heat transfer medium online to compensate for wear and tear during long-term operation.
[0021] The conveying system is used to transport the heat transfer medium obtained from magnetic separation to the medium replenishment and storage bin. The conveying system can specifically employ pneumatic conveying equipment, bucket elevators, etc.
[0022] In some preferred embodiments, the mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device further includes a pyrolysis gas collection and treatment system. This system is connected to the middle section and / or discharge end of the rotary kiln body and is used to collect and treat the gaseous products generated during material pyrolysis. It is understood that the gaseous products may include substances that are liquid under normal conditions but gaseous in the working environment of the rotary kiln body. Furthermore, the pyrolysis gas collection and treatment system can export the gaseous products (e.g., pyrolysis oil and gas) and transport them to a subsequent condensation separation and purification system, ultimately obtaining pyrolysis oil products and syngas.
[0023] The electromagnetic induction system, in conjunction with the control system, enables non-contact synchronous heating and driving of the heat transfer medium. The control system can independently and precisely adjust the kiln rotation speed, the power (for temperature control), and the phase (for driving direction and intensity) of each section of the electromagnetic coil, achieving precise and flexible control of pyrolysis temperature, material residence time, and mixing intensity to adapt to the processing needs of different types of carbonaceous organic solid waste. Specifically: temperature control is achieved by controlling the power of each section of the electromagnetic coil, thereby independently controlling the temperature of the heat transfer medium in each reaction zone within the kiln to meet the pyrolysis kinetics requirements of different materials; residence time is controlled by adjusting the kiln rotation speed via a frequency converter, controlling the total residence time of the material within the kiln; mixing intensity and direction control are achieved by adjusting the current phase (difference) and timing of adjacent electromagnetic coils (groups), flexibly switching the direction (forward, reverse, or pulsed disturbance) and intensity of the traveling wave magnetic field, realizing real-time regulation of the mixing intensity. For example, for easily agglomerated waste plastics, high-frequency reciprocating drive can be used to enhance shear mixing; for biomass with good flowability, stable axial drive can be used to promote uniform heating.
[0024] The rotary kiln of this invention possesses excellent magnetic field penetration. The alternating magnetic field generated by the electromagnetic coil can effectively penetrate the non-magnetic or weakly magnetic kiln wall, inducing eddy current losses (Joule heating effect) and hysteresis losses within the ferromagnetic heat transfer medium inside the kiln, causing it to rapidly self-heat. The heat transfer medium thus becomes a mobile high-temperature internal heat source distributed within the material layer inside the kiln. This design achieves a fundamental shift in heat transfer from traditional external wall conduction to internal volumetric heating; heat is released directly from within the material, without needing to penetrate the kiln wall and material layer, shortening the heat transfer path by more than 80%.
[0025] Furthermore, the traveling wave magnetic field applies a directional electromagnetic driving force (i.e., Lorentz force) to the magnetized heat transfer medium, thereby driving it to perform directional and controllable active circulation within the material bed. Unlike existing technologies that rely on solid structures such as lifting plates driven by the passive rotation of the kiln body, the movement of the heat transfer medium in this invention is not limited by the rotational speed and direction of the kiln body. The direction, speed, and mode of movement (axial propulsion, radial disturbance, reciprocating shearing, etc.) can be independently adjusted according to process requirements, achieving active stirring at the microscale.
[0026] The heat transfer medium is the key energy carrier for achieving efficient heat transfer and mixing in this invention. The selection of its material requires comprehensive consideration of magnetic permeability, heat capacity, wear resistance, and high-temperature stability. Specifically, ferromagnetic materials with high Curie temperatures can be used, such as 430 stainless steel balls (good oxidation resistance), iron-aluminum interoxide compounds (high wear resistance), and magnetic ceramic balls with a heat-resistant coating (cost optimization). For special corrosive atmospheres, coated iron-based media can be considered.
[0027] In some preferred embodiments, the volumetric filling rate of the heat transfer medium within the rotary kiln is controlled at 5%-15%, such as 10% or 12%. An excessively high filling rate affects the mechanical load on the kiln and the flow of materials, while an excessively low rate results in insufficient heat storage.
[0028] In some preferred embodiments, the particle size of the heat transfer medium is 5-20 mm, such as 6 mm, 8 mm, 10 mm, 12 mm, 15 mm, etc. If the particle size is too small, the magnetic responsiveness is weak and it is easy to flow out with the material; if the particle size is too large, the specific surface area is small and the heat transfer efficiency decreases.
[0029] In some preferred embodiments, the operating frequency of the electromagnetic coil is 30-400kHz, such as 100kHz, 150kHz, 200kHz, 250kHz, and 300kHz. For heat transfer media of different particle sizes, the frequency can be adjusted to optimize the effective penetration and heating effect of the electromagnetic field, thereby obtaining the best heating efficiency and electromagnetic force conversion efficiency. Generally, a lower operating frequency (e.g., 30-100kHz) can be selected for processing larger heat transfer media (e.g., particle size 15-20mm), while a higher operating frequency (e.g., 200-400kHz) can be selected for processing smaller heat transfer media (e.g., particle size 5-10mm).
[0030] In some preferred embodiments, the operating temperature of the heat transfer medium within the rotary kiln is 450-800℃, such as 500℃, 540℃, 550℃, 560℃, 650℃, etc. The temperature of the heat transfer medium can be controlled by adjusting the power of the electromagnetic coil through a control system.
[0031] Heat transfer media subjected to prolonged use at high temperatures face problems such as oxidation, wear, and thermal fatigue. The control system of this invention can achieve long-term stable operation of the heat transfer media by real-time monitoring of temperature and drive efficiency.
[0032] In industrial applications, a magnetic separator can be installed at the discharge end to separate and discharge the demagnetized or damaged heat transfer medium and replenish it with new medium to ensure that the system performance remains stable.
[0033] In this invention, the movement of the heat transfer medium is a synergy and superposition of the macroscopic mechanical motion of the rotary kiln and the microscopic electromagnetic drive. The rotation of the kiln body drives the entire material bed (including the heat transfer medium) forward slowly and generates a discharge, achieving axial conveying and macroscopic mixing. Simultaneously, within the discharge bed, a traveling wave magnetic field continuously drives the heat transfer medium to actively directional flow, including axial movement along the kiln body and / or radial disturbance achieved through phase switching. This flow can penetrate the heat transfer dead zone formed by the material's own accumulation, rapidly transferring heat from the high-temperature heat transfer medium to the low-temperature material region. The synergistic superposition of the macroscopic mechanical motion of the rotary kiln and various other motions, such as the microscopic electromagnetic drive, creates a complex three-dimensional spiral propulsion trajectory between the heat transfer medium and the material. This mode ensures sufficient contact and exchange of heat and material at the microscopic level, fundamentally solving the problems of delayed heating and large temperature gradients in the central region of traditional rotary kilns, and achieving a uniform temperature field distribution across the entire cross-section.
[0034] In some preferred embodiments, the mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device further includes a feeding system; the feeding system is connected to the feed end and is used for continuous, sealed, and quantitative material conveying. Further, the feeding system may include a hopper and a screw feeder.
[0035] In some preferred embodiments, the mobile internal heat source-driven and circulated electromagnetic induction pyrolysis device further includes a discharge system; the discharge system is connected to the discharge end and is used to discharge pyrolysis products (such as residues, carbon black, etc.).
[0036] In a second aspect, the present invention provides the application of the mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device described in the first aspect for pyrolyzing carbon-containing organic solid waste to obtain pyrolysis oil, syngas and / or carbon-containing solid materials.
[0037] Thirdly, the present invention provides an electromagnetic induction pyrolysis method with mobile internal heat source co-driving and circulation, using the electromagnetic induction pyrolysis device with mobile internal heat source co-driving and circulation described in the first aspect. The electromagnetic induction pyrolysis method with coordinated driving and circulation of the mobile internal heat source includes: The material and heat transfer medium are fed into the rotary kiln body through the feed end; When a high-frequency alternating current is passed through an electromagnetic coil, an alternating magnetic field is generated, which magnetizes the heat transfer medium inside the rotary kiln and causes it to heat up on its own, thus promoting the pyrolysis of the material. The rotary kiln body rotates; the control system regulates the current phase (difference) and timing of adjacent electromagnetic coils (groups) to construct a controllable traveling wave magnetic field along the axial direction within the rotary kiln body, thereby driving the magnetized heat transfer medium to carry the material together in radial and / or axial motion within the rotary kiln body (e.g., moving from the feed end to the discharge end, moving from the discharge end to the feed end, reciprocating motion, etc.); pyrolysis products are obtained at the discharge end; The circulation system receives the heat transfer medium discharged from the discharge end and re-inputs it from the feed end into the rotary kiln body.
[0038] In some preferred embodiments, the material includes carbon-containing organic solid waste. Further, the carbon-containing organic solid waste preferably includes one or more of waste tires, biomass (e.g., wood chips, straw, etc.), and waste plastics (e.g., high-density polyethylene, etc.).
[0039] In some preferred embodiments, the rotary kiln body rotates at a speed of 1-10 rpm, such as 3 rpm, 4 rpm, 5 rpm, 8 rpm, etc. For example, the rotary kiln body can be slowly rotated at a speed of 1-10 rpm using a conventional roller-gear drive system.
[0040] In some preferred embodiments, the residence time of the material inside the rotary kiln is 10-20 minutes, such as 12 minutes, 15 minutes, 18 minutes, etc.
[0041] Compared with the prior art, the beneficial effects of this invention are as follows: This invention provides a mobile, internally heated, synergistically driven, and circulated electromagnetic induction pyrolysis device and method. An alternating electromagnetic field is generated by energizing electromagnetic coils to heat the heat transfer medium. The current phase of adjacent electromagnetic coils can be programmed and controlled, forming a controllable traveling wave magnetic field inside the kiln. This traveling wave magnetic field synchronously drives the heat transfer medium to circulate directionally along the axial and / or radial directions, maintaining the uniformity of temperature distribution within the kiln. The temperature of the heat transfer medium can be controlled between 450-800℃. The heat transfer medium heats organic solid waste to undergo a pyrolysis reaction, yielding products such as pyrolysis oil, syngas, and carbonaceous solid materials. This invention is based on the eddy currents generated in the heat transfer medium within the alternating electromagnetic field. Through the thermal effect of these eddy currents, the medium becomes a distributed, mobile, high-temperature heat source for heating. Compared to traditional externally heated rotary kilns that rely on indirect heat transfer, this invention achieves volumetric heating from the inside out. Heat is released directly from within the material. Meanwhile, the heat transfer medium is actively driven by the traveling wave magnetic field to achieve three-dimensional spiral propulsion within the material bed. The synergistic effect of mechanical and electromagnetic forces enables the heat transfer medium to actively penetrate the core dead zone of the material accumulation layer. The radial temperature difference inside the kiln is controlled within ±15℃, which significantly improves the uniformity and quality stability of the pyrolysis products.
[0042] This invention integrates a magnetic separation and conveying system into an electromagnetically heated rotary kiln, achieving closed-loop recycling of the heat transfer medium. This overcomes the fundamental shortcomings of unidirectional medium movement and accumulation at the discharge port, and the fact that the device can only operate intermittently, ensuring long-term continuous and stable operation. The control system can independently and in real-time adjust the power and phase of the electromagnetic coil, achieving decoupled control of the heat transfer medium temperature, movement trajectory, mixing intensity, and material residence time. It can be flexibly customized for different material characteristics such as easily agglomerated waste plastics, highly volatile biomass, and highly abrasive waste tires, demonstrating excellent material adaptability and product control capabilities. Attached Figure Description
[0043] Figure 1 This is a schematic diagram of the structure and method of an electromagnetic induction pyrolysis device with coordinated driving and circulation of a mobile internal heat source according to the present invention. The solid arrows in the figure indicate the direction of movement of materials or heat transfer media.
[0044] Figure 2 for Figure 1 The diagram shows the principle of the traveling wave magnetic field driving the directional movement of the heat transfer medium in the electromagnetic induction pyrolysis device with coordinated drive and circulation of the mobile internal heat source. The dashed arrow in the diagram indicates the direction of the traveling wave magnetic field. Detailed Implementation
[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Operating methods not specifically specified in the following embodiments are generally performed under conventional conditions or as recommended by the manufacturer.
[0046] The present invention provides a mobile internal heat source co-driven and circulating electromagnetic induction pyrolysis device, the core of which is to realize non-contact heating and directional driving of the heat transfer medium through segmented electromagnetic coils, and to coordinate with the macroscopic mechanical motion of the rotary kiln to form a three-dimensional spiral propulsion composite motion mode, thereby achieving efficient heat transfer and uniform pyrolysis.
[0047] Combination Figure 1 , Figure 2 A mobile electromagnetic induction pyrolysis device with coordinated internal heat source drive and circulation includes an air intake system 1, a rotary kiln body with good magnetic field penetration 2, an electromagnetic induction system 3, a ferromagnetic heat transfer medium 4, a feeding system 5, a discharging system 6, a pyrolysis gas collection and treatment system 7, a control system 8, and a circulation system.
[0048] The rotary kiln body 2 includes a feed end for receiving materials and a discharge end for discharging pyrolysis products. The kiln wall of the rotary kiln body 2 is non-magnetic. The rotary kiln body 2 is installed at an angle of 1°-5°, with the feed end higher than the discharge end.
[0049] The feeding system 5 includes a hopper and a screw feeder, with the hopper connected to the feed end via the screw feeder. The air intake system 1, connected to the screw feeder, is used to introduce inert gases or other gases into the rotary kiln body 2. The discharge system 6, connected to the discharge end, is used to discharge pyrolysis products and the heat transfer medium 4. The circulation system receives the heat transfer medium 4 discharged from the discharge system 6 and re-inputs it from the feed end back into the rotary kiln body 2. The circulation system includes a magnetic separator 9, a medium replenishment and storage bin 10, and a conveying system. The magnetic separator 9, connected to the discharge system 6, is used for magnetic separation of the heat transfer medium 4 and solid products. The medium replenishment and storage bin 10, connected to the magnetic separator 9 and the screw feeder, is used to receive and store the heat transfer medium 4 obtained from the magnetic separation and to supply the heat transfer medium 4 to the screw feeder. The conveying system transports the heat transfer medium 4 obtained from the magnetic separation to the medium replenishment and storage bin 10. The screw feeder can continuously, sealedly, and quantitatively convey materials, gases, and the heat transfer medium 4.
[0050] The pyrolysis gas collection and treatment system 7 is connected to the middle section and / or the discharge end of the rotary kiln body 2, and is used to collect and treat the gaseous products generated by the pyrolysis of materials. The pyrolysis gas collection and treatment system 7 can export the gaseous products (such as pyrolysis oil and gas) and transport them to the subsequent condensation separation and purification system to finally obtain pyrolysis oil products and syngas.
[0051] The electromagnetic induction system 3 includes multiple sets of electromagnetic coils arranged around the outer wall of the rotary kiln body 2 and independently controlled by the control system 8 in segments along the axial direction of the rotary kiln body 2. The electromagnetic coils are used to pass in high-frequency alternating current to generate an alternating magnetic field, thereby magnetizing the heat transfer medium 4 in the rotary kiln body 2 and generating heat on its own to promote the pyrolysis of the material.
[0052] The control system 8 is used to regulate the current phase (difference) and timing of adjacent electromagnetic coils (groups) (e.g., using a control strategy with a 120° phase difference in three-phase AC power) to construct a controllable traveling wave magnetic field along the axial direction within the rotary kiln body 2. This drives the magnetized heat transfer medium 4 to carry the material and move radially and / or axially within the rotary kiln body 2 (e.g., from the feed end to the discharge end, from the discharge end to the feed end, reciprocating motion, etc.). The control system 8 can independently and precisely adjust the kiln rotation speed, the power (controlling temperature) and phase (controlling driving direction and intensity) of each section of electromagnetic coils, achieving precise and flexible control of pyrolysis temperature, material residence time, and mixing intensity to adapt to the processing needs of different types of carbonaceous organic solid waste and other materials.
[0053] The aforementioned mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device can be used to pyrolyze carbon-containing organic solid waste to obtain pyrolysis oil, syngas and / or carbon-containing solid materials.
[0054] A mobile internal heat source-assisted driving and circulation electromagnetic induction pyrolysis method, employing the aforementioned mobile internal heat source-assisted driving and circulation electromagnetic induction pyrolysis device, includes: The material and heat transfer medium are fed into the rotary kiln body 2 through the feed end; When high-frequency alternating current is passed through the electromagnetic coil, an alternating magnetic field is generated, which magnetizes the heat transfer medium in the rotary kiln body 2 and generates heat on its own, promoting the pyrolysis of the material. The rotary kiln body 2 rotates; the control system 8 regulates the current phase (difference) and timing of adjacent electromagnetic coils (groups) to construct a controllable traveling wave magnetic field along the axial direction within the rotary kiln body 2, thereby driving the magnetized heat transfer medium 4 to carry the material and move radially and / or axially within the rotary kiln body 2 (e.g., moving from the feed end to the discharge end, moving from the discharge end to the feed end, reciprocating motion, etc.); the discharge system 6 obtains the pyrolysis products; The circulation system receives the heat transfer medium discharged from the discharge system 6 and re-feeds it from the feed end to the rotary kiln body 2 via a screw feeder.
[0055] The following examples and comparative examples illustrate the treatment process for different types of organic solid waste (waste tires, agricultural biomass, waste plastics, mixed materials, etc.) to demonstrate the wide applicability and excellent technical effects of the present invention.
[0056] In the following embodiments, the above-described method is used. Figure 1 , Figure 2 The mobile internal heat source coordinated drive and circulation electromagnetic induction pyrolysis device and method shown can achieve precise control of pyrolysis temperature, material residence time and mixing intensity by independently adjusting the kiln rotation speed, power and phase of each section of electromagnetic coil through the control system 8.
[0057] Example 1: Pyrolysis treatment of waste high-density polyethylene (HDPE): This embodiment uses high-density polyethylene (HDPE) waste plastic granules with a particle size of 5-10 mm as raw material. HDPE is prone to melting, sticking to the walls, and clumping during pyrolysis, which is a challenge in pyrolysis treatment. Magnetic ceramic balls with a diameter of 8 mm (coated with a heat-resistant layer) are selected as the heat transfer medium 4, with a volume filling rate of 15% in the kiln body to provide sufficient heat and hybrid power. The rotary kiln body 2 is set with an inclination angle of 1° and a rotation speed of 8 rpm. The operating frequency of the electromagnetic coil is set to 250 kHz through the control system 8, and the power of the electromagnetic coil is adjusted according to the pyrolysis process requirements to stabilize the temperature of the heat transfer medium 4 at 550 ± 10℃. At the same time, a traveling wave magnetic field is constructed in the kiln by adjusting the current phase difference between adjacent electromagnetic coil groups (using a 120° three-phase phase difference). Considering the easy melting of HDPE, the traveling wave magnetic field is set to a high-frequency reciprocating commutation mode (i.e., the direction of travel is switched every 5 seconds), driving the heat transfer medium 4 to perform reciprocating shearing motion in the molten plastic, effectively disrupting the continuity of the melt and preventing sticking to the walls and clumping. The residence time of the pyrolysis reaction is controlled at 10 minutes. The circulation system operates synchronously, and the heat transfer medium is returned to the feed end for recycling after magnetic separation. Test results show that the radial temperature distribution inside the kiln is uniform, with a kiln wall temperature of 552℃ and a kiln center temperature of 545℃, a temperature difference of only 7℃; the pyrolysis oil / wax yield is as high as 86.2 wt.%, the discharge is smooth, there are no obvious deposits on the kiln wall, and the product is evenly distributed. The unit energy consumption is as low as 1.68 kWh / kg of raw material, and with the heat transfer medium recycled and heated online, the unit can operate continuously and stably.
[0058] To verify the technological advancements of this invention compared to existing technologies, the following three comparative examples are used as benchmarks for comparison.
[0059] Comparative Example 1: The ferromagnetic heat transfer medium in the device of this invention is removed, and replaced with an L-shaped ferromagnetic lifting plate (made of iron, with rounded corners at the L-shaped bends) installed on the inner wall of the kiln. Heating is performed using the same traveling wave magnetic field (120° phase difference). The same waste plastic granules (HDPE waste plastic with a particle size of 5-10mm) are used as the raw material in Example 1. For convenient discharge, the kiln body is tilted at 3°, the rotation speed is 4 rpm, and the pyrolysis reaction residence time is 15 minutes. The electromagnetic coil operates at a frequency of 150kHz to achieve a target temperature of 500-600℃ inside the kiln. The rest is the same as in Example 1.
[0060] Test results showed that the radial temperature distribution inside the kiln was 580℃ at the kiln wall and 512℃ at the kiln center, with a temperature difference as high as 68℃. The pyrolysis oil / wax yield was only 68.5 wt.%, and the quality of the pyrolysis wax / oil was poor, with obvious coking and significant adhesion to the wall at the discharge port. The unit energy consumption was as high as 3.12 kWh / kg of raw material, and because the lifting plates were fixed and there was no heat transfer medium circulation, the device could only operate intermittently.
[0061] Comparative Example 2: Rotary kiln solid heat carrier pyrolysis technology: The same waste plastic granules (HDPE waste plastic with a particle size of 5-10 mm) as in Example 1 were used, and a traditional solid heat carrier pyrolysis process was employed. 12 mm diameter ceramic balls (non-magnetic, ordinary alumina balls) were selected as the solid heat carrier, with a volumetric filling rate of 12%. The ceramic balls were preheated to 550°C in an external furnace and then mechanically conveyed into the kiln to mix with the material. The kiln inclination angle was 3°, the rotation speed was 4 rpm, there was no electromagnetic heating system, and the pyrolysis reaction residence time was 15 minutes. Because the ceramic balls could not be reheated within the kiln, the temperature gradually decreased during operation, requiring intermittent replenishment of the heat carrier. Test results showed a significant axial temperature gradient within the kiln, with the feed temperature at 550°C and the discharge temperature dropping to 420°C; the pyrolysis oil / wax yield was 72.8 wt.%, indicating secondary cracking due to localized overheating, uneven product distribution, and a unit energy consumption of 2.45 kWh / kg of raw material (including preheating energy consumption). Furthermore, the heat carrier required external preheating and could not be circulated online, forcing the device to operate intermittently.
[0062] Comparative Example 3: Using the same waste plastic pellets as in Example 1 (HDPE waste plastic with a particle size of 5-10 mm), the kiln was tilted at 3°, rotated at 4 rpm, with the electromagnetic coil operating at 150 kHz, and the target kiln wall temperature was 560°C. The kiln interior had no lifting plates or heat transfer medium; heating relied solely on the kiln wall's own heat generation. The pyrolysis reaction residence time was 15 minutes. Test results showed that the radial temperature distribution within the kiln was 560°C at the kiln wall and 485°C at the kiln center, a temperature difference of 75°C. The pyrolysis oil / wax yield was only 50.4 wt.%, indicating insufficient pyrolysis in the central region and the presence of unreacted plastic melt. The unit energy consumption was as high as 3.45 kWh / kg of raw material. Although the device could operate continuously, its heat transfer efficiency was extremely low.
[0063] Table 1 shows a comparison of the effects of pyrolysis technology in Example 1 and Comparative Examples 1-3 on the treatment of HDPE waste plastics.
[0064] Table 1 As can be seen from the data in Table 1: Compared with Comparative Example 1: The device of the present invention changes the fixed kiln wall heat source to a mobile internal heat source, reduces the radial temperature difference from 68°C to 7°C, significantly increases the pyrolysis oil yield from 50.4 wt.% to 86.2 wt.%, and reduces the unit energy consumption by 46.2%, thus completely solving the fundamental defect of easy wall coking in the pyrolysis of waste plastics in the prior art.
[0065] Compared to Comparative Example 2 (solid heat carrier pyrolysis): Although traditional solid heat carrier pyrolysis also uses internal heating heat transfer, the heat carrier requires external preheating, cannot be replenished online, and its movement relies on mechanical mixing, resulting in a significant axial temperature gradient. This invention achieves online heating and active driving of the heat carrier through electromagnetic induction, ensuring a constant and controllable heat carrier temperature. The operation mode changes from intermittent to continuous, increasing the pyrolysis oil yield by 14.6 wt.% and reducing unit energy consumption by 31.4%.
[0066] Compared to Comparative Example 3 (medium-free electromagnetic heating): the external heat transfer of the kiln wall using simple electromagnetic heating cannot penetrate the material's interior, resulting in severe lag in heating the central area. This invention, through the active movement of the heat transfer medium, directly releases heat into the material's interior, increasing the pyrolysis oil yield from 50.4 wt.% to 86.2 wt.%, an increase of nearly two times, fully demonstrating the advantages of the mobile internal heat source technology.
[0067] Example 2: Pyrolysis treatment of waste tire pellets: This embodiment uses waste tire pellets with a particle size of 5-10 mm as raw material. 430 stainless steel balls with a diameter of 12 mm are selected as the heat transfer medium 4, with a volumetric filling rate of 12% within the kiln. The rotary kiln body 2 is set at an inclination angle of 3° and a rotation speed of 4 rpm. The control system 8 sets the operating frequency of the electromagnetic coil to 150 kHz and adjusts the coil power according to the pyrolysis process requirements to stabilize the temperature of the heat transfer medium 4 at 550 ± 10℃. Simultaneously, by adjusting the current phase difference between adjacent coil groups (using a 120° three-phase phase difference), an axial traveling wave magnetic field is constructed within the kiln, propelling the stainless steel balls in a directional circulatory flow along the axial direction within the material bed. The pyrolysis reaction residence time is controlled at 15 minutes. After the reaction, the gas is separated by the pyrolysis gas collection and treatment system 7, yielding a pyrolysis oil yield of 41.5 wt.%, a carbon black yield of 34.8 wt.%, and a syngas yield of 23.7 wt.%. The entire pyrolysis process operates stably, with uniform temperature distribution within the kiln and no coking observed.
[0068] Example 3: Pyrolysis treatment of corn stalks (biomass): This embodiment uses corn stalk pellets with a particle size of 3-8 mm as raw material. Due to the low bulk density and poor thermal conductivity of biomass raw materials, this embodiment selects iron-aluminum metal oxide spheres with a particle size of 6 mm as heat transfer medium 4, with a filling rate of 10%, to enhance heat storage capacity and mixing effect. The kiln body inclination angle is 2°, and the rotation speed is 5 rpm. The electromagnetic coil operating frequency is set to 300 kHz, and the medium temperature is controlled at 500℃. To enhance mixing, the traveling wave magnetic field is set to an alternating axial and radial disturbance mode by adjusting the coil phase, so that the heat transfer medium moves in multiple directions within the material bed, fully penetrating the straw accumulation layer, and the pyrolysis residence time is 12 minutes. The test results show that the biochar yield is 29.5 wt.%, the pyrolysis gas yield (mainly containing H2, CO, and CH4) yield is 51.2 wt.%, and the pyrolysis oil yield is 19.3 wt.%. The device effectively solves the common problems of slow heat transfer and delayed temperature rise in biomass pyrolysis.
[0069] Example 4: Pyrolysis treatment of waste tire and wood chip mixture: To verify the adaptability of the device to mixed materials, this embodiment uses a mixture of waste tire pellets (30% by mass, 5-8mm in diameter) and sawdust (70% by mass, 3-5mm in diameter) as raw materials. The heat transfer medium 4 is 10mm diameter 430 stainless steel balls with a filling rate of 12%. The kiln inclination angle is 4°, and the rotation speed is 3rpm. Considering the differences in the pyrolysis characteristics of the two materials, the control system 8 divides the heating zone into two independently controlled sections: the front section (preheating section) has a lower coil power and a medium temperature of approximately 450℃, allowing the material to be slowly preheated and begin dehydration / softening; the rear section (main pyrolysis section) has an increased coil power, raising the medium temperature to 650℃. Simultaneously, by adjusting the phase of the rear coil, the intensity of the traveling wave magnetic field in this area is enhanced, driving the heat transfer medium to undergo high-intensity stirring, ensuring uniform heat transfer. The total pyrolysis residence time is 18 minutes. The system operates stably, with pyrolysis oil yield of 35.2 wt.%, syngas yield of 44.5 wt.%, and char yield of 20.3 wt.%, achieving efficient and synergistic conversion of the mixture.
[0070] Example 5: Stability verification of the heat transfer medium circulation system: To verify the long-term operational stability of the heat transfer medium circulation system, the process conditions of Example 1 were used for continuous operation for 72 hours. Samples were taken every 8 hours to test the mass loss, magnetic response intensity, and pyrolysis product distribution of the heat transfer medium (magnetic ceramic balls). The results showed that after 72 hours of operation, the mass loss rate of the heat transfer medium was <0.3%, the magnetic response intensity remained above 98.5% of its initial value, the pyrolysis oil yield fluctuated within ±1.2 wt.% at different times, and the temperature field distribution within the kiln remained stable without abnormal fluctuations. These results demonstrate that the heat transfer medium circulation system (magnetic separation + conveying + medium replenishment and storage) designed in this invention can effectively ensure the long-term continuous and stable operation of the device.
[0071] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.
Claims
1. A mobile electromagnetic induction pyrolysis device with coordinated internal heat source drive and circulation, characterized in that, It includes a control system, an electromagnetic induction system, a circulation system, a ferromagnetic heat transfer medium, and a rotary kiln body with good magnetic field penetration; the rotary kiln body includes a feed end for receiving materials and a discharge end for discharging pyrolysis products. The electromagnetic induction system includes multiple sets of electromagnetic coils arranged around the outer wall of the rotary kiln and independently controlled by the control system in segments along the axial direction of the rotary kiln. The electromagnetic coils are used to pass in high-frequency alternating current to generate an alternating magnetic field, thereby magnetizing the heat transfer medium inside the rotary kiln and generating heat on its own to promote the pyrolysis of the material. The control system is used to regulate the current phase and timing of adjacent electromagnetic coils to build a controllable traveling wave magnetic field along the axial direction in the rotary kiln, thereby driving the magnetized heat transfer medium to carry the material and move radially and / or axially in the rotary kiln. The circulation system is used to receive the heat transfer medium discharged from the discharge end and reintroduce it into the rotary kiln body from the feed end.
2. The mobile internal heat source-assisted driving and circulation electromagnetic induction pyrolysis device according to claim 1, characterized in that, The walls of the rotary kiln are non-magnetic; The rotary kiln body is installed at an inclined position with the feed end higher than the discharge end, and the inclination angle is 1°-5°.
3. The mobile internal heat source-assisted driving and circulating electromagnetic induction pyrolysis device according to claim 1, characterized in that, The mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device also includes an air intake system; the air intake system is connected to the feed end and is used to introduce gas into the rotary kiln body; the gas includes inert gas.
4. The mobile internal heat source-assisted driving and circulation electromagnetic induction pyrolysis device according to claim 1, characterized in that, The circulation system includes a magnetic separator, a media replenishment and storage bin, and a conveying system; The magnetic separator is connected to the discharge end and is used for magnetic separation of the heat transfer medium and solid products; The medium replenishment and storage bin connects the magnetic separator and the feed end, and is used to receive and store the heat transfer medium obtained by magnetic separation and to provide heat transfer medium to the feed end. The conveying system is used to transport the heat transfer medium obtained by magnetic separation to the medium replenishment and storage bin.
5. The mobile internal heat source-assisted driving and circulation electromagnetic induction pyrolysis device according to claim 1, characterized in that, The mobile internal heat source co-driven and circulated electromagnetic induction pyrolysis device also includes a pyrolysis gas collection and treatment system; the pyrolysis gas collection and treatment system is connected to the middle section and / or the discharge end of the rotary kiln body, and is used to collect and treat the gaseous products generated by the pyrolysis of materials.
6. The mobile internal heat source-assisted driving and circulating electromagnetic induction pyrolysis device according to claim 1, characterized in that, The operating frequency of the electromagnetic coil is 30-400kHz; The particle size of the heat transfer medium is 5-20 mm; The volumetric filling rate of the heat transfer medium inside the rotary kiln is controlled at 5%-15%; The working temperature of the heat transfer medium inside the rotary kiln is 450-800℃.
7. The mobile internal heat source-driven and circulating electromagnetic induction pyrolysis device according to any one of claims 1-6 is used for pyrolysis of carbon-containing organic solid waste to obtain pyrolysis oil, syngas and / or carbon-containing solid materials.
8. A mobile internal heat source-assisted driving and circulating electromagnetic induction pyrolysis method, characterized in that, The electromagnetic induction pyrolysis device with mobile internal heat source cooperative drive and circulation as described in any one of claims 1-6 is used. The electromagnetic induction pyrolysis method with coordinated driving and circulation of the mobile internal heat source includes: The material and heat transfer medium are fed into the rotary kiln body through the feed end; When a high-frequency alternating current is passed through an electromagnetic coil, an alternating magnetic field is generated, which magnetizes the heat transfer medium inside the rotary kiln and causes it to heat up on its own, thus promoting the pyrolysis of the material. The rotary kiln body rotates; the control system adjusts the current phase and timing of adjacent electromagnetic coils to construct a controllable traveling wave magnetic field along the axial direction in the rotary kiln body, thereby driving the magnetized heat transfer medium to carry the material together to move radially and / or axially in the rotary kiln body; pyrolysis products are obtained at the discharge end. The circulation system receives the heat transfer medium discharged from the discharge end and re-inputs it from the feed end into the rotary kiln body.
9. The electromagnetic induction pyrolysis method with coordinated driving and circulation of a mobile internal heat source according to claim 8, characterized in that, The materials include carbon-containing organic solid waste; The carbon-containing organic solid waste includes one or more of waste tires, biomass, and waste plastics.
10. The electromagnetic induction pyrolysis method with coordinated driving and circulation of a mobile internal heat source according to claim 8 or 9, characterized in that, The rotational speed of the rotary kiln body is 1-10 rpm; The residence time of materials inside the rotary kiln is 10-20 minutes.