A Precise and Continuous Gasification System and Method for Circuit Board Resin Based on Reaction Kinetics Regulation

Abstract

This invention relates to the field of waste circuit board recycling technology, specifically disclosing a precise and continuous gasification system and method for circuit board resin based on reaction kinetics control. The method includes: acquiring the three-dimensional temperature field distribution within the gasifier and detecting the concentration of resin gasification product components using a multi-component flue gas analyzer; dividing the circumference of the gasifier into multiple fan-shaped microwave radiation zones and dynamically adjusting the microwave power density of each zone using a time-sequential rotation method; establishing a pulsed microwave heating strategy, precisely controlling the heating pulse parameters according to the rate of change in gasification product concentration, and combining dual-frequency microwave synergistic heating to achieve efficient gasification of both deep and surface layers of resin; constructing a convection exhaust mechanism to control the gas flow rate and temperature, and drawing in gasification product gas through negative pressure. This application achieves precise and continuous control of the resin gasification process, improving the precise gasification of resin in circuit boards.

Description

Technical Field

[0001] This invention relates to the field of waste circuit board recycling technology, and specifically discloses a precise and continuous vaporization system and method for circuit board resin based on reaction kinetics control. Background Technology

[0002] Waste circuit boards are typically processed using high-temperature methods such as pyrolysis and gasification to recover combustible gases and enrich metal components, which is one of the mainstream routes for electronic waste resource utilization. However, existing processes generally face the following problems in actual operation: During the heating stage, the circuit board resin often exhibits significant spatial inhomogeneity, with some areas rapidly carbonizing after a sudden temperature increase, while adjacent areas remain in a state of insufficient gasification. This uneven heating directly causes large fluctuations in the composition of gaseous products, posing significant challenges to subsequent condensation, purification, and separation processes. When heat-treating thick or multi-layered circuit boards, uneven heating makes complete gasification difficult, producing a considerable proportion of residues, thereby reducing the overall organic matter recovery rate and affecting resource utilization efficiency.

[0003] Currently, there is a lack of technical solutions that can simultaneously eliminate the above-mentioned non-uniformity under continuous operating conditions and ensure that the circuit board resin is fully vaporized.

[0004] In view of this, this application proposes a precise and continuous vaporization system and method for circuit board resin based on reaction kinetics control. Summary of the Invention

[0005] To achieve the above objectives, this application provides a precise and continuous vaporization system and method for circuit board resin based on reaction kinetics control, the specific technical solution of which is as follows:

[0006] A precise and continuous vaporization method for circuit board resin based on reaction kinetics control includes:

[0007] A multi-point temperature sensor array is uniformly deployed on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier. A multi-component flue gas analyzer is installed at the gasifier exhaust port to detect the concentration of various resin gasification product components.

[0008] The circumference of the gasifier is divided into multiple sector-shaped microwave radiation zones. The sector-shaped microwave radiation zones emit microwaves in a time-sequential manner. The microwave power density of each sector-shaped microwave radiation zone is dynamically adjusted according to the three-dimensional temperature field distribution.

[0009] A pulsed microwave heating strategy was established to adjust the microwave heating pulse parameters based on the detected rate of change in the concentration of resin vaporization product components.

[0010] A dual-frequency microwave synergistic heating mechanism is adopted, in which low-frequency microwaves deeply heat the resin of the circuit board, while high-frequency microwaves heat the surface layer of the resin.

[0011] A convection exhaust mechanism for the gasifier is constructed, in which gas is introduced from one end of the gasifier, the gas flow rate is controlled and the gas is preheated, and the gasified resin gas is drawn in at the other end under negative pressure.

[0012] Preferably, a multi-point temperature sensor array is uniformly deployed in a horizontal layered layout on the inner wall of the gasifier to form a three-dimensional temperature measurement grid; the collected temperature data is used to construct a continuous temperature field distribution function through a three-dimensional interpolation algorithm to obtain the three-dimensional temperature field distribution;

[0013] An infrared spectroscopy flue gas analyzer is installed at the gasifier exhaust port. The infrared spectroscopy flue gas analyzer continuously monitors the concentration of each component of the resin gasification product at a fixed sampling frequency. By establishing the first and second derivatives of the time series of the resin gasification product component concentrations, the rate change and acceleration characteristics of the resin gasification reaction are evaluated in real time.

[0014] Preferably, the circumference of the gasifier is evenly divided into multiple fan-shaped microwave radiation zones along the radial direction. Each fan-shaped microwave radiation zone has an independent microwave power supply device installed at a corresponding position on the outer wall of the gasifier to heat the circuit board in the gasifier.

[0015] The magnetrons of each sector microwave radiation zone are adjusted through an independent power control unit. The sector microwave radiation zones are numbered, and the microwave transmission power of each sector microwave radiation zone is adjusted according to the numbering.

[0016] A time-sequential microwave transmission mechanism is constructed to allow multiple sectors to operate simultaneously. In each working cycle, multiple non-adjacent sector microwave radiation areas are selected to transmit microwaves simultaneously. When multiple sectors in the current cycle have completed their microwave transmission work, adjacent sectors take over the microwave transmission work.

[0017] Preferably, a microwave power density adjustment algorithm based on radial-axial temperature field feedback of the gasifier is established; the temperature field data of the gasifier is mapped to each sector microwave radiation zone; the average temperature distribution of the sector at different height levels is calculated, and the volume average temperature of the sector is calculated; the target temperature and temperature deviation are defined; and the microwave power density is adjusted using an adaptive proportional-integral-derivative control law.

[0018] Preferably, the power allocation strategy is dynamically optimized based on the first and second derivatives of the flue gas component concentration; the first derivative of the resin gasification product component concentration is calculated based on the obtained resin gasification product component concentration to characterize the gasification reaction rate; and the second derivative is calculated to characterize the reaction acceleration.

[0019] A comprehensive gasification dynamic index is constructed, and the microwave power is adjusted based on the comprehensive gasification dynamic index.

[0020] Preferably, a pulsed microwave heating strategy is established, replacing the continuous microwave heating mode with an intermittent pulsed heating mode;

[0021] The pulse parameters of a single sector microwave pulse sequence are defined, including pulse width, pulse interval, peak pulse power, and pulse duty cycle; pulsed microwave heating is carried out by alternating periodic energy input and thermal diffusion processes; the pulse parameters of pulsed microwave heating are adjusted based on the rate of change in the concentration of resin vaporization product components.

[0022] Preferably, a heat accumulation protection algorithm is established to monitor the heat accumulation effect during the resin vaporization process, define a local heat accumulation index, and insert a cooling interval when the local heat accumulation index exceeds the critical value to extend the pulse interval of the sector.

[0023] Establish a phase coordination control mechanism for microwave pulse sequences to avoid electromagnetic interference and power fluctuations caused by multiple sector pulses reaching their peak values ​​simultaneously by staggering the phases.

[0024] Preferably, a dual-frequency microwave synergistic heating mechanism is constructed, in which a dual-frequency magnetron combination, including a low-frequency magnetron and a high-frequency magnetron, is configured in each sector microwave radiation area to uniformly heat the resin of the circuit board according to the low-frequency microwave and the high-frequency microwave.

[0025] Time-division multiplexing technology is used for coordinated control to avoid mutual interference between the two microwave frequencies.

[0026] Preferably, preheated carrier gas is supplied at the gas inlet end of the gasifier, and a spiral tube electric heater is used to preheat the carrier gas; a negative pressure suction device is configured at the gas outlet end of the gasifier, and the exhaust pipeline is designed with heat preservation to maintain the pipeline temperature within a predetermined range.

[0027] An internal convection circulation control mechanism is established for the gasifier. By adjusting the matching relationship between the inlet gas flow rate and the exhaust negative pressure, an axial convection field is formed inside the furnace. At the same time, the transit time of the carrier gas inside the furnace is controlled by adjusting the gas flow rate.

[0028] The circuit board resin precision continuous vaporization system based on reaction kinetics control is used to realize the circuit board resin precision continuous vaporization method based on reaction kinetics control, and includes: a data acquisition module, a multi-sector microwave emission module, a pulse microwave heating module, a dual-frequency microwave heating module, and a resin vaporization flow module.

[0029] The data acquisition module uniformly deploys a multi-point temperature sensor array on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier, and installs a multi-component flue gas analyzer at the gasifier exhaust port to detect the concentration of various types of resin gasification product components.

[0030] The multi-sector microwave emitting module divides the circumference of the gasifier into multiple sector-shaped microwave radiation zones. The sector-shaped microwave radiation zones emit microwaves in a time-sequential manner, and the microwave power density of each sector-shaped microwave radiation zone is dynamically adjusted according to the three-dimensional temperature field distribution.

[0031] The pulsed microwave heating module establishes a pulsed microwave heating strategy, adjusting the microwave heating pulse parameters based on the detected change rate of resin vaporization product component concentration.

[0032] The dual-frequency microwave heating module employs a dual-frequency microwave synergistic heating mechanism, where low-frequency microwaves deeply heat the resin in the circuit board, while high-frequency microwaves heat the surface of the resin in the circuit board.

[0033] The resin gasification circulation module is used to construct the convection exhaust mechanism of the gasifier. Gas is introduced from one end of the gasifier, the gas flow rate is controlled and the gas is preheated, and the gasified resin gas is drawn in at the other end with negative pressure.

[0034] The beneficial effects of this application are as follows: This application achieves real-time monitoring of the three-dimensional temperature field inside the gasifier by uniformly arranging a multi-point temperature sensor array on the inner wall of the gasifier. Combined with a multi-component flue gas analyzer at the exhaust port, it effectively detects the concentration of multiple types of resin gasification products, thereby improving the controllability and safety of the gasification process.

[0035] This application divides the circumference of the gasifier into multiple sector-shaped microwave radiation zones and uses time-sequential microwave emission to avoid localized continuous heating that could cause hot spots. Combined with temperature field information, the power density of each zone is dynamically adjusted to effectively improve heating uniformity and prevent localized overheating and incomplete gasification.

[0036] This application establishes a pulsed microwave heating strategy that can flexibly adjust microwave heating parameters according to the rate of change in the concentration of resin gasification product components, achieve a dynamic balance between intermittent energy input and heat diffusion, effectively reduce the risk of heat accumulation, and improve the ability to finely control the gasification reaction.

[0037] This application employs a dual-frequency microwave synergistic heating mechanism, utilizing low-frequency microwaves to achieve deep heating of the resin and high-frequency microwaves to enhance surface heating, ensuring that both inner and outer resin layers can be fully vaporized, significantly improving the overall vaporization efficiency of thick circuit boards.

[0038] This application constructs a convection exhaust mechanism, which combines preheated carrier gas and negative pressure suction to form a stable airflow channel, improve the timely discharge efficiency of gasification products, and reduce the risk of gasification residue and secondary pollution. Attached Figure Description

[0039] Figure 1 A flowchart of the precise and continuous vaporization method for circuit board resin based on reaction kinetics control provided in this application;

[0040] Figure 2 A flowchart of multi-sector microwave partitioning and dynamic control provided for this application;

[0041] Figure 3 A flowchart of pulsed microwave heating and heat accumulation protection provided for this application;

[0042] Figure 4 The flowchart of the dual-frequency microwave coordinated heating control provided in this application;

[0043] Figure 5 The structural diagram of the circuit board resin precision continuous vaporization system based on reaction kinetics control provided in this application. Detailed Implementation

[0044] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0045] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0046] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of this application. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0047] Example 1

[0048] Reference Figure 1 This is the first embodiment of the present application, which provides a method for precise and continuous vaporization of circuit board resin based on reaction kinetics control.

[0049] Step 1: Distribute a multi-point temperature sensor array evenly on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier. Install a multi-component flue gas analyzer at the gasifier exhaust port to detect the concentration of various types of resin gasification products.

[0050] A horizontally layered array of fiber optic temperature sensors is uniformly deployed on the inner wall of the gasifier. For example, eight horizontal temperature measurement layers are arranged along the furnace axial direction. Each layer has 12 measurement points evenly distributed circumferentially within the same horizontal plane. Adjacent horizontal temperature measurement layers are spaced at equal intervals, forming a regular three-dimensional temperature measurement grid. The fiber optic temperature sensors are made of high-temperature resistant quartz fiber and are led out to an external fiber optic demodulator through a sealed conduit pre-installed in the furnace wall. The spatial coordinates of each temperature sensor measurement point are determined using a cylindrical coordinate system. Precise positioning, among which, Indicates the first The position of the circumference angle Indicates the first Each axial height position. Specifically, This indicates the temperature sensing point at the 7th angle and the 2nd altitude layer.

[0051] Temperature data collected by a temperature sensor array is used to construct a continuous temperature field distribution function using a three-dimensional interpolation algorithm. ,in, Let r represent the time variable, z represent the circumferential angle variable, and z represent the axial height variable. The interpolation algorithm uses the radial basis function method to interpolate the discrete measurement point temperature values. Mapped to continuous spatial temperature distribution: ;in, for The weighting coefficient of the measuring point is mainly determined based on the spatial distance between the interpolation point and each temperature sensor measuring point. Generally, the closer the interpolation point is to the measuring point, the greater the weight is assigned, and the farther the point is, the smaller the weight is assigned. The weighting coefficient is automatically calculated based on the actual spatial distribution of each measuring point. For radial basis functions, Represents the spatial distance norm.

[0052] Using fiber optic temperature sensors to collect temperature data inside the gasifier not only enables dynamic tracking of the gasifier's temperature but also avoids measurement errors caused by the self-heating of temperature sensors such as thermocouples or platinum resistance thermometers during microwave heating. Through a horizontally layered high-density temperature measurement network, the temperature distribution characteristics of each height layer during resin gasification can be accurately captured, clearly reflecting the temperature gradient changes inside the gasifier and providing reliable temperature field data support for the zoned control of microwave power in the gasifier.

[0053] An infrared spectrometer is installed at the gasifier exhaust port. The analyzer has a built-in standard spectral library and can simultaneously detect multiple products generated during the gasification of epoxy resin, phenolic resin, and polyimide resin, including organic gas components such as phenols, aldehydes, ketones, and small-molecule hydrocarbons. A particulate filter is installed at the probe end of the infrared spectrometer to prevent resin solid particles from entering the analyzer. The flue gas sampling pipeline of the infrared spectrometer is designed with heat tracing and insulation to maintain the pipeline temperature at least 50°C above the flue gas dew point temperature, preventing condensable components from liquefying in the pipeline and causing measurement errors.

[0054] The flue gas analyzer continuously monitors the concentration of each component in the resin gasification products at a fixed sampling frequency. ,in, Indicates the first gas components, The first resin vaporization product representing the time variable t Components By establishing the first derivative of the time series concentration of resin vaporization products. and second derivative The system can assess the rate changes and acceleration characteristics of the resin vaporization reaction in real time. When a sharp increase in the concentration of a certain characteristic product is detected, it indicates that the corresponding type of resin is rapidly vaporizing, thereby determining the dominant type of vaporization reaction. For example, when the phenol concentration rises from 100 ppm to 800 ppm within 5 seconds, the concentration change rate reaches 140 ppm / s, indicating that the epoxy resin is in a vigorous decomposition and vaporization stage.

[0055] The multi-dimensional monitoring system constructed in this step can comprehensively grasp the reaction state of the resin gasification process in the gasifier, realize accurate perception and quantitative characterization of the resin gasification process, and provide a complete state information basis for subsequent reaction kinetic control.

[0056] Step 2: Divide the circumference of the gasifier into multiple sector-shaped microwave radiation zones. These zones emit microwaves in a time-sequential manner, and the microwave power density of each zone is dynamically adjusted based on the temperature field. These sector-shaped microwave radiation zones can be simply referred to as sectors, and multiple sector-shaped zones can be referred to as multiple sectors. See also... Figure 2 This is a flowchart of the multi-sector microwave partitioning and dynamic control process for this step.

[0057] The circumference of the gasifier is uniformly divided into N sector-shaped microwave radiation zones along the radial direction, with the central angle of each sector-shaped microwave radiation zone being . Generally, N is set to be an even number and satisfies To ensure spatial resolution of microwave radiation and flexibility for simultaneous operation of multiple sectors, each sector of microwave radiation is equipped with an independent microwave feeding device at a corresponding position on the outer wall of the gasifier, including a magnetron, a waveguide, and a microwave feed inlet. For example, an industrial-grade continuous wave magnetron is used, operating at a frequency of 2.45 GHz, with a single-tube rated power range of 1-3 kW. Microwave energy is introduced into the gasifier through a rectangular waveguide; a quartz glass sealing window is installed at the connection between the waveguide and the furnace wall to ensure both microwave transmission and furnace sealing.

[0058] Each sector of the microwave radiation region's magnetron is regulated by an independent power control unit, which employs a silicon controlled rectifier (SCR) voltage regulation method to achieve continuous power adjustment from 0-100%. The sector microwave radiation regions are numbered, and the angular range of the i-th sector microwave radiation region is... ,in, , The instantaneous microwave power density of each sector of microwave radiation is expressed as: Through precise sector-shaped partitioning design, differentiated heating of resin materials in different locations within the gasifier can be achieved, avoiding the uneven temperature field problem caused by traditional overall heating methods.

[0059] A time-sequential microwave transmission mechanism is constructed to allow multiple sectors to operate simultaneously. At each operating moment, m non-adjacent sector microwave radiation regions are selected to simultaneously transmit microwaves. For example, the following settings are configured: This means that one-third of the non-adjacent sectors are simultaneously subjected to microwave heating. This specifies the number of non-adjacent sectors that can perform microwave heating simultaneously, ensuring that there is at least one sector between any two sectors operating simultaneously. Define the sector activation matrix. Where j represents the timing step, and i and k represent the sector numbers, i∈{1,2,..., }, k∈{1,2,..., }, This indicates that the i-th sector is active in the j-th timing step. This indicates that the state is off. Construct activation constraints: For any time step j, if... and Then it must satisfy (Consider cyclic boundary conditions).

[0060] Using a spiral-driven rotation strategy, the set of activated sectors in the j-th timing step is: ,in, This represents the set of active sectors in the j-th timing step. There are sectors, and the k-th sector in the set of activated sectors for the j-th timing step is... The spiral activation mode ensures that each sector receives an equal activation duration within a complete rotation cycle, while maintaining the spatial dispersion of activated sectors. The base time slice length is defined as... Complete rotation cycle Each sector is activated exactly once during this cycle.

[0061] For example, for a sector-shaped microwave radiation region with N=12, the first timing step activates sectors {1,4,7,10}, the second timing step activates sectors {2,5,8,11}, and the third timing step activates sectors {3,6,9,12}. This multi-sector simultaneous operation mode improves heating efficiency to that of a single-sector operation mode. This significantly shortens the time required for resin vaporization and avoids electromagnetic interference and thermal stress on the circuit board caused by simultaneous microwave heating of all sectors.

[0062] A microwave power density adjustment algorithm based on radial-axial temperature field feedback from the gasifier is established; the temperature field data of the gasifier is mapped to each sector of microwave radiation; the average temperature distribution of the i-th sector of microwave radiation at different heights is calculated. ,in, Represent the radial integration domain of the i-th sector of microwave radiation; further calculate the volume average temperature of this sector. Where H is the effective height of the gasifier; the target temperature is defined. and temperature deviation .

[0063] Microwave power density regulation employs an adaptive proportional-integral-derivative control law:

[0064]

[0065] in, Based on power density, This is the proportionality coefficient. The integral coefficient is... These are the derivative coefficients. The control parameters are dynamically adjusted based on the temperature response characteristics: when the temperature change rate is large, the derivative action is increased to suppress overshoot; when there is a steady-state deviation, the integral action is enhanced to eliminate steady-state error. The adaptive control strategy can respond quickly to temperature changes while maintaining heating stability.

[0066] The power allocation strategy is dynamically optimized based on the first and second derivatives of the flue gas component concentration. This is based on the first and second derivatives obtained in step 1. Concentration of gas components Calculate its first derivative. Characterizing the gasification reaction rate, the second derivative Characterizing reaction acceleration. Constructing a comprehensive gasification dynamic index. :

[0067]

[0068] in, For the first The weighting coefficients of the gases, Let M be the acceleration influence factor, and M be the total number of monitored gas types. When... and When, it indicates that the gasification reaction is accelerating; when but When the reaction rate is at a certain level, it indicates that although the reaction rate is still increasing, it has begun to slow down.

[0069] Establish a power regulation strategy based on reaction dynamics, when the second derivative of a key product (such as phenols) is detected. hour, The concentration of the key product. To accelerate the threshold, indicating that the reaction is too violent, the power density of all activated sectors is immediately reduced to [a certain value]. ,in, To reduce the power density of the activated sector, This is the attenuation coefficient. When the first derivative... Within the target range And when the second derivative is close to zero, and These are the lower and upper limits of the reaction rate, respectively, indicating that the reaction is in a steady state and maintains the current power constant. When the first derivative... When, determine based on the sign of the second derivative: if This indicates that the reaction continues to slow down, and the power density needs to be increased. ,in, This represents the increase in power density.

[0070] The multi-sector simultaneous operation of the partitioned controllable microwave heating mechanism established in this step improves the heating efficiency of the resin in the circuit board; the spiral propulsion rotation strategy ensures that all sectors receive equal heating opportunities, the simultaneous operation of multiple non-adjacent sectors avoids local thermal stress concentration, the intelligent power adjustment based on the radial-axial temperature field maintains the temperature uniformity of the entire vaporization space, and the thermal stress protection mechanism ensures the safety and stability of equipment operation. Ultimately, it achieves efficient, uniform, and controllable vaporization of the circuit board resin, significantly improving the resin vaporization quality and processing efficiency.

[0071] Step 3: Establish a pulsed microwave heating strategy, adjusting the microwave heating pulse parameters based on the detected rate of change in the concentration of resin vaporization products. (See also...) Figure 3 This is a flowchart of the pulsed microwave heating and heat accumulation protection process for this step.

[0072] A pulsed microwave heating strategy is established to replace the continuous microwave heating mode with an intermittent pulsed heating mode. The pulse parameters of the microwave pulse sequence for a single sector are defined, including the pulse width. Pulse interval Pulse power peak and pulse duty cycle Pulsed heating, through alternating periods of energy input and heat diffusion, avoids the resin carbonization problem caused by excessive heat accumulation on the resin surface and the formation of localized hot spots, which is common with continuous microwave heating.

[0073] Based on the rate of change in resin gasification product concentration, the pulse parameters of the pulsed microwave heating are adjusted; based on the concentration changes detected by the flue gas analyzer... Concentration of characteristic gasification products Based on the calculated gasification reaction rate and reaction acceleration Define the comprehensive gasification rate index. ,in, For the first The weighting coefficient of each product The total number of gas types monitored; when Exceeding the set reaction rate limit This indicates that the resin vaporization reaction is too vigorous, posing a risk of localized overheating. Immediately adjust the pulse width. ,in, The adjusted pulse width, To achieve the target vaporization rate, the average power input is reduced by shortening the pulse width, thereby suppressing excessively rapid vaporization reactions.

[0074] A heat accumulation protection algorithm is established to monitor the heat accumulation effect during resin vaporization. A local heat accumulation index is defined. ,in For the first Each sector in Instantaneous power density at time t, To assess the time window, Let be the thermal diffusion time constant of the resin material. Exceeding the critical value At that time, a forced cooling interval is inserted, extending the pulse interval of that sector to [a later timeframe]. ,in, For the extended pulse interval, This refers to the interval adjustment coefficient; the critical value. The setting method needs to be based on the thermal diffusion characteristics of the resin material and the safety requirements of the vaporization process, combined with the calculation formula of the local heat accumulation index and determined through experimental data. By selecting different types of resin materials, the local heat accumulation effect is monitored under simulated actual heating conditions, the critical point that leads to material carbonization or performance degradation is recorded, and this value is set as the critical value. In addition, the critical value can be adjusted according to the thermal stability characteristics of different resins to ensure adaptability and reliability. Dynamic adjustment based on the intermittent period of heat accumulation history can effectively prevent carbonization caused by excessive heat accumulation inside the resin.

[0075] A pulse power peak optimization strategy was established based on the vaporization characteristics of different types of resins by analyzing the characteristic product spectra of epoxy resin, phenolic resin, and polyimide resin. For example, for epoxy resin, which has poor thermal stability, when a sharp increase in the concentration of bisphenol A decomposition products is detected, the pulse power peak is reduced. ,in, This represents the power correction factor for epoxy resin. For polyimide resins with high thermal stability, the peak power is appropriately increased to ensure sufficient vaporization. For example, when the phenol concentration change rate reaches 150 ppm / s, the peak pulse power is reduced from 2.5 kW to 1.8 kW, while the pulse width is shortened from 200 ms to 140 ms.

[0076] Establish a phase coordination control mechanism for pulse sequences to ensure electromagnetic compatibility when multiple sectors operate simultaneously. Define the pulse phase difference between adjacent operating sectors. , Indicates the first Each sector, Indicates the relationship with the first Adjacent sectors, of which, This represents the number of sectors that are activated simultaneously. Phase staggering avoids electromagnetic interference and power fluctuations caused by multiple sector pulses reaching their peak values ​​simultaneously. A pulse synchronization triggering system is established, where the pulse sequences of all sectors are controlled by a unified clock signal to ensure the stability of the phase relationship. For example, for four simultaneously operating sectors, phase differences are set to 0°, 90°, 180°, and 270°, respectively, forming a uniformly distributed power output mode.

[0077] The pulsed microwave heating strategy established in this step effectively prevents the formation of hot spots inside the resin through intermittent energy input. Real-time feedback adjustment based on the rate of change of vaporization product concentration ensures the stability and controllability of the vaporization process. The heat accumulation protection algorithm completely eliminates the risk of local carbonization. Multi-frequency pulse superposition and phase coordination control further improve the uniformity of heating, enabling precise temperature control and vaporization of circuit board resin, and significantly improving the recycling quality of circuit board products after resin vaporization.

[0078] Step 4: A dual-frequency microwave synergistic heating mechanism is employed. Low-frequency microwaves provide deep heating to the resin in the circuit board, while high-frequency microwaves provide surface heating. (See also...) Figure 4 This is a flowchart of the dual-frequency microwave coordinated heating control process for this step.

[0079] A dual-frequency microwave synergistic heating mechanism is constructed, configuring a dual-frequency magnetron combination, including a low-frequency magnetron and a high-frequency magnetron, in each sector of microwave radiation. For example, the low-frequency microwave is selected in the 915MHz band, and the high-frequency microwave is selected in the 2450MHz band. The low-frequency and high-frequency microwaves are coupled through a power combiner and then input into the gasification furnace via the same waveguide system. The longer wavelength of the low-frequency microwave allows its penetration depth to reach more than 80% of the thickness of the circuit board resin layer, achieving volumetric heating of the resin interior. The formula for calculating the microwave penetration depth in the resin medium is as follows: ,in, Indicates the microwave penetration depth. The speed of light in a vacuum. For microwave frequencies, This is the dielectric loss factor of the resin material. This formula allows for the precise calculation of the penetration depth of microwaves of different frequencies in a specific resin material, thereby optimizing frequency selection. The low-frequency microwave generator uses a continuous-wave magnetron and is equipped with a water-cooling system to maintain stable operating temperature. The output power is continuously adjustable within the range of 500W-3000W, with a power stability better than ±2%.

[0080] High-frequency microwaves have a relatively shallow penetration depth, primarily affecting the resin surface layer within 1-2 mm. The temperature gradient generated by rapid surface heating promotes heat conduction from the interior to the exterior, complementing the deeper heating effect of low-frequency microwaves. The high-frequency microwave generator also uses an industrial-grade magnetron and is equipped with a pulse modulation circuit. The two microwave frequencies are coupled through a power combiner to ensure that the two microwave signals do not interfere with each other.

[0081] The power allocation between low and high frequencies follows a dynamic adjustment principle, with the power ratio determined based on the monitored resin thickness distribution. The power allocation coefficient is defined as follows: ,in, Low-frequency microwave power, This is high-frequency microwave power. In the initial stage of gasification, The value is set in the range of 0.7-0.8 to ensure sufficient preheating of the resin; as vaporization proceeds, the value is gradually reduced. The value is increased to 0.4-0.5, and surface heating is strengthened to maintain a stable vaporization rate.

[0082] To avoid mutual interference between the two microwave frequencies, time-division multiplexing technology is used for coordinated control. In each heating cycle... Inside, the duty cycle of low-frequency microwaves is The duty cycle of high-frequency microwave is ,satisfy Reserve 5% of the time for microwave switching and stabilization. For example, when... When set to 100ms, low-frequency microwaves are emitted for the first 70ms, high-frequency microwaves for the next 25ms, and a 5ms buffer time in between. This alternating heating method ensures the continuity of heating while avoiding the standing wave problem caused by frequency aliasing.

[0083] This step, through the synergistic effect of low-frequency deep heating and high-frequency surface heating, significantly reduces the internal temperature gradient of the resin, controlling the temperature difference within 20°C, effectively avoiding the problem of surface overheating and carbonization while the internal temperature is insufficient. Dual-frequency synergistic heating improves the utilization efficiency of microwave energy and enhances heating stability. The precise vaporization heating control and efficient energy utilization in this step ensure the uniformity and completeness of the resin vaporization reaction.

[0084] Step 5: Construct a convection exhaust mechanism for the gasifier. Introduce gas from one end of the gasifier, control the gas flow rate and preheat the gas. At the other end, set up a negative pressure system to draw in the gasified resin gas.

[0085] Preheated carrier gas is supplied at the gasifier's inlet. A spiral tube electric heater preheats the carrier gas, typically to 290-310°C. A mass flow controller precisely regulates the carrier gas flow rate to ensure sufficient enthalpy for the gas to maintain the temperature environment necessary for resin gasification. Precisely controlled inlet gas effectively prevents condensation of resin gasification products due to temperature fluctuations.

[0086] A negative pressure suction device is installed at the exhaust end of the gasifier, using a centrifugal fan to provide stable negative pressure, which is regulated by frequency converter speed control. The exhaust end pipeline is insulated, and the pipeline temperature must be maintained within the range of 240-260°C to prevent condensation and blockage of the resin gasification products during transportation. The negative pressure provided by the centrifugal fan at the exhaust end suctions the gasified resin, allowing the resin gasification products to be promptly removed from the reaction area.

[0087] An internal convection circulation control mechanism is established within the gasifier. By adjusting the matching relationship between the carrier gas inlet velocity and the exhaust negative pressure, a stable axial convection field is formed within the furnace. The transit time of the carrier gas within the furnace is controlled by adjusting the airflow velocity. Controlling the transit time ensures complete resin gasification while avoiding secondary pyrolysis caused by excessive residence of resin gasification products. The internal convection circulation also homogenizes the temperature field within the gasifier. Convection circulation rapidly removes excess heat from localized hot spots and transfers heat to relatively cooler areas, achieving dynamic equilibrium of the temperature field within the furnace.

[0088] The convection exhaust mechanism constructed in this step effectively solves the problem of hot spot concentration during microwave heating by using the forced convection of the carrier gas. It rapidly diffuses the heat from the local overheated area to the entire reaction space, preventing the resin from carbonizing due to local overheating. At the same time, it ensures that the vaporization products of the inner layer resin of the circuit board are extracted, thereby improving the overall vaporization efficiency of the resin in the circuit board.

[0089] Example 2

[0090] Reference Figure 5 This is the second embodiment of the present application, which provides a circuit board resin precision continuous vaporization system based on reaction kinetics control.

[0091] The system includes a data acquisition module, a multi-sector microwave emission module, a pulsed microwave heating module, a dual-frequency microwave heating module, and a resin vaporization and circulation module.

[0092] The data acquisition module uniformly deploys a multi-point temperature sensor array on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier, and installs a multi-component flue gas analyzer at the gasifier exhaust port to detect the concentration of various types of resin gasification products.

[0093] The multi-sector microwave emitting module divides the circumference of the gasifier into multiple sector-shaped microwave radiation zones. The sector-shaped microwave radiation zones emit microwaves in a time-sequential manner, and the microwave power density of each sector-shaped microwave radiation zone is dynamically adjusted according to the temperature field.

[0094] The pulsed microwave heating module establishes a pulsed microwave heating strategy, adjusting the microwave heating pulse parameters based on the detected change rate of resin vaporization product concentration.

[0095] The dual-frequency microwave heating module employs a dual-frequency microwave synergistic heating mechanism, where low-frequency microwaves deeply heat the resin in the circuit board, while high-frequency microwaves heat the surface layer of the resin.

[0096] The resin gasification circulation module is used to construct the convection exhaust mechanism of the gasifier. Gas is introduced from one end of the gasifier, the gas flow rate is controlled and the gas is preheated, and the gasified resin gas is drawn in by negative pressure at the other end.

[0097] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings or direct couplings or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0098] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments under the guidance of this application without departing from the spirit and scope of protection of the claims. All of these variations are within the protection scope of this application.

Claims

1. A method for precise and continuous vaporization of circuit board resin based on reaction kinetics control, characterized in that, include: A multi-point temperature sensor array is uniformly deployed on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier. A multi-component flue gas analyzer is installed at the gasifier exhaust port to detect the concentration of various resin gasification product components. The circumference of the gasifier is divided into multiple sector-shaped microwave radiation zones. The sector-shaped microwave radiation zones emit microwaves in a time-sequential manner. The microwave power density of each sector-shaped microwave radiation zone is dynamically adjusted according to the three-dimensional temperature field distribution. A pulsed microwave heating strategy is established to replace the continuous microwave heating mode with an intermittent pulsed heating mode; the pulse parameters of the microwave pulse sequence for a single sector are defined, including pulse width, pulse interval, peak pulse power, and pulse duty cycle. Pulsed microwave heating is achieved by alternating periodic energy input and thermal diffusion processes; the pulse parameters of pulsed microwave heating are adjusted based on the rate of change in the concentration of resin vaporization product components. A heat accumulation protection algorithm is established to monitor the heat accumulation effect during the resin vaporization process. A local heat accumulation index is defined. When the local heat accumulation index exceeds the critical value, a cooling interval is inserted to extend the pulse interval of the sector. Establish a phase coordination control mechanism for microwave pulse sequences to avoid electromagnetic interference and power fluctuations caused by multiple sector pulses reaching their peak values ​​simultaneously through phase staggering; A dual-frequency microwave synergistic heating mechanism is adopted, in which low-frequency microwaves deeply heat the resin of the circuit board, while high-frequency microwaves heat the surface layer of the resin. A convection exhaust mechanism for the gasifier is constructed, in which gas is introduced from one end of the gasifier, the gas flow rate is controlled and the gas is preheated, and the gasified resin gas is drawn in at the other end under negative pressure.

2. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 1, characterized in that, A multi-point temperature sensor array is uniformly deployed in a horizontal layered layout on the inner wall of the gasifier to form a three-dimensional temperature measurement grid; the collected temperature data is used to construct a continuous temperature field distribution function through a three-dimensional interpolation algorithm to obtain the three-dimensional temperature field distribution; An infrared spectroscopy flue gas analyzer is installed at the gasifier exhaust port. The infrared spectroscopy flue gas analyzer continuously monitors the concentration of each component of the resin gasification product at a fixed sampling frequency. By establishing the first and second derivatives of the time series of the resin gasification product component concentrations, the rate change and acceleration characteristics of the resin gasification reaction are evaluated in real time.

3. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 2, characterized in that, The circumference of the gasifier is evenly divided into multiple fan-shaped microwave radiation zones along the radial direction. Each fan-shaped microwave radiation zone has an independent microwave power supply device installed at the corresponding position on the outer wall of the gasifier to heat the circuit board in the gasifier. The magnetrons of each sector microwave radiation zone are adjusted through an independent power control unit. The sector microwave radiation zones are numbered, and the microwave transmission power of each sector microwave radiation zone is adjusted according to the numbering. A time-sequential microwave transmission mechanism is constructed to allow multiple sectors to operate simultaneously. In each working cycle, multiple non-adjacent sector microwave radiation areas are selected to transmit microwaves simultaneously. When multiple sectors in the current cycle have completed their microwave transmission work, adjacent sectors take over the microwave transmission work.

4. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 3, characterized in that, A microwave power density adjustment algorithm based on radial-axial temperature field feedback from the gasifier is established; the temperature field data of the gasifier is mapped to each sector microwave radiation zone; the average temperature distribution of the sector at different heights is calculated, and the volume average temperature of the sector is calculated. The target temperature and temperature deviation are defined, and the microwave power density is adjusted using an adaptive proportional-integral-derivative control law.

5. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 4, characterized in that, The power allocation strategy is dynamically optimized based on the first and second derivatives of the flue gas component concentrations; the first derivative of the resin gasification product component concentrations is calculated based on the obtained resin gasification product component concentrations to characterize the gasification reaction rate. And to calculate the second derivative, used to characterize reaction acceleration; A comprehensive gasification dynamic index is constructed, and the microwave power is adjusted based on the comprehensive gasification dynamic index.

6. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 5, characterized in that, A dual-frequency microwave synergistic heating mechanism is constructed, in which a dual-frequency magnetron combination, including a low-frequency magnetron and a high-frequency magnetron, is configured in each sector microwave radiation area to uniformly heat the resin of the circuit board according to the low-frequency microwave and the high-frequency microwave. Time-division multiplexing technology is used for coordinated control to avoid mutual interference between the two microwave frequencies.

7. The method for precise and continuous vaporization of circuit board resin based on reaction kinetics control according to claim 6, characterized in that, Preheated carrier gas is supplied at the gas inlet of the gasifier and preheated using a spiral tube electric heater; a negative pressure suction device is installed at the exhaust end of the gasifier and the exhaust pipeline is insulated to maintain the pipeline temperature within a predetermined range. An internal convection circulation control mechanism is established for the gasifier. By adjusting the matching relationship between the inlet gas flow rate and the exhaust negative pressure, an axial convection field is formed inside the furnace. At the same time, the transit time of the carrier gas inside the furnace is controlled by adjusting the gas flow rate.

8. A circuit board resin precision continuous vaporization system based on reaction kinetics control, used to implement the circuit board resin precision continuous vaporization method based on reaction kinetics control as described in any one of claims 1 to 7, characterized in that, include: Data acquisition module, multi-sector microwave transmission module, pulsed microwave heating module, dual-frequency microwave heating module, and resin vaporization and circulation module; The data acquisition module uniformly deploys a multi-point temperature sensor array on the inner wall of the gasifier to obtain the three-dimensional temperature field distribution inside the gasifier, and installs a multi-component flue gas analyzer at the gasifier exhaust port to detect the concentration of various types of resin gasification product components. The multi-sector microwave emitting module divides the circumference of the gasifier into multiple sector-shaped microwave radiation zones. The sector-shaped microwave radiation zones emit microwaves in a time-sequential manner, and the microwave power density of each sector-shaped microwave radiation zone is dynamically adjusted according to the three-dimensional temperature field distribution. The pulsed microwave heating module establishes a pulsed microwave heating strategy, adjusting the microwave heating pulse parameters based on the detected change rate of resin vaporization product component concentration. The dual-frequency microwave heating module employs a dual-frequency microwave synergistic heating mechanism, where low-frequency microwaves deeply heat the resin in the circuit board, while high-frequency microwaves heat the surface of the resin in the circuit board. The resin gasification circulation module is used to construct the convection exhaust mechanism of the gasifier. Gas is introduced from one end of the gasifier, the gas flow rate is controlled and the gas is preheated, and the gasified resin gas is drawn in at the other end with negative pressure.

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