A circulating type formaldehyde adsorption regeneration system for plywood gluing

Abstract

The present application belongs to the technical field of formaldehyde waste gas treatment for plywood gluing, and relates to a circulating formaldehyde adsorption regeneration system for plywood gluing. The present application introduces an electrostatic-ultrasonic coupling demister and a humidity self-adaptive purification adsorption path, overcomes the problem of efficiency decline of the traditional adsorption process under the conditions of paint mist particle interference and humidity fluctuation, and improves the adaptability to complex working conditions. A kinetic model of adsorbent performance attenuation and a multi-source data intelligent control strategy are established, the accurate monitoring of adsorption saturation and the dynamic adjustment of adsorption breakthrough threshold and regeneration process parameters are realized, and the problem of decline of treatment effect caused by adsorbent performance attenuation is solved. Through the design of hierarchical regeneration technology and tail gas catalytic oxidation device, the energy utilization efficiency in the adsorbent regeneration process is optimized, and high-concentration formaldehyde mixed gas is completely decomposed into harmless substances, avoiding the risk of secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of formaldehyde waste gas treatment technology for plywood coating, and relates to a circulating formaldehyde adsorption and regeneration system for plywood coating. Background Technology

[0002] Formaldehyde emissions generated during the plywood coating process are a common source of industrial pollution, and their treatment is crucial for protecting the production environment and surrounding ecosystems. Currently, methods for treating formaldehyde-containing emissions mainly include physical adsorption, chemical oxidation, and catalytic decomposition. In practical applications, activated carbon adsorption is widely used due to its ease of operation and low cost. However, traditional activated carbon adsorption processes have certain limitations, especially in environments with high humidity or a high concentration of paint mist particles, where adsorption efficiency is significantly affected.

[0003] In existing technologies, fixed-bed adsorption towers filled with a single adsorbent are typically used to purify formaldehyde-containing air. These methods often rely on fixed adsorption cycles and regeneration conditions, and the adsorption saturation state is determined by monitoring the formaldehyde concentration at the outlet. Some improved processes have introduced simple humidity control measures, such as adding dehumidifiers to the inlet duct, but these measures are difficult to fully adapt to complex and variable actual operating conditions. Furthermore, existing technologies primarily rely on empirical data to assess adsorbent performance degradation, lacking dynamic adjustment mechanisms, which increases the risk of adsorption breakthrough and reduces regeneration efficiency.

[0004] The aforementioned technologies have shown certain shortcomings in addressing formaldehyde emissions generated during plywood coating processes. Due to significant humidity fluctuations and the presence of paint mist particles in the coating workshop environment, traditional methods are prone to reduced treatment effectiveness due to adsorbent surface clogging or competitive adsorption by water molecules. Furthermore, the gradual decline in adsorbent performance with each regeneration cycle has not been adequately addressed, and effective compensation strategies are lacking. Monitoring methods primarily focus on formaldehyde concentration data, failing to comprehensively consider multi-source information such as temperature and pressure, resulting in inaccurate adsorption saturation determination and impacting system stability and economic efficiency. Summary of the Invention

[0005] In view of this, in order to solve the problems mentioned in the background art, a circulating formaldehyde adsorption and regeneration system for plywood adhesive is proposed.

[0006] The objective of this invention can be achieved through the following technical solution: a circulating formaldehyde adsorption and regeneration system for plywood coating, comprising: an anti-interference pretreatment module, which uses an electrostatic-ultrasonic coupling demister to treat formaldehyde-containing air and remove paint mist particles.

[0007] The humidity adaptive analysis module guides the formaldehyde-containing air, which has undergone the anti-interference pretreatment, through at least one adsorption tower based on the real-time monitored ambient humidity, and outputs purified air.

[0008] The saturation monitoring module collects the formaldehyde concentration at the inlet and outlet of the adsorption tower, calculates the real-time adsorption saturation based on the pre-constructed adsorbent performance decay kinetic model, and compares it with the preset adsorption breakthrough threshold to generate a switching command.

[0009] The staged desorption and regeneration module, according to the switching command, cuts off the self-purification adsorption pipeline of the saturated adsorption tower and connects it to the regeneration pipeline, introduces the regeneration medium into the saturated adsorption tower and heats it to form a high-concentration formaldehyde mixed gas.

[0010] The exhaust gas treatment module introduces the high-concentration formaldehyde mixed gas into the catalytic oxidation reactor to oxidize and decompose the formaldehyde in it.

[0011] The performance degradation assessment and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance degradation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the staged desorption and regeneration steps accordingly to compensate for performance degradation.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention removes paint mist particles by means of anti-interference pretreatment and electrostatic-ultrasonic coupling demister, thereby avoiding the blockage of the pores of the adsorbent by the paint mist, effectively protecting the adsorbent, improving its adsorption efficiency and service life, and ensuring the stable progress of the subsequent adsorption process.

[0013] This invention is based on humidity adaptive analysis and sets up two paths filled with modified activated carbon and hydrophobic zeolite adsorbents respectively. By switching according to humidity, the appropriate adsorbent can play an efficient adsorption role under different humidity environments, thus ensuring the stability of formaldehyde adsorption effect.

[0014] This invention uses saturation monitoring to calculate real-time adsorption saturation based on an adsorbent performance decay kinetic model. Combined with a preset threshold to generate a switching command, it achieves accurate determination of regeneration timing, avoids energy waste and formaldehyde leakage, and improves the system's economy and reliability.

[0015] This invention employs a staged desorption and regeneration process. First, water molecules are desorbed at a specific temperature, and then formaldehyde molecules are desorbed at an even higher temperature. This improves desorption efficiency, reduces the impact of residual water molecules on subsequent adsorption, and simultaneously reduces energy consumption and enhances regeneration performance.

[0016] This invention updates the kinetic model of adsorbent performance degradation by evaluating and compensating for performance degradation, and dynamically adjusts the adsorption breakthrough threshold or regeneration process parameters, effectively compensating for the impact of adsorbent performance degradation and ensuring long-term stable and efficient operation of the system. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram showing the connections of the various modules in the system of the present invention.

[0019] Figure 2 This is a schematic diagram of the electrostatic-ultrasonic coupling demister of the present invention.

[0020] Figure 3 This is a schematic diagram illustrating the switching principle of the humidity-adaptive purification adsorption path.

[0021] Figure 4 This is a flowchart of the update process for the kinetic model of adsorbent performance degradation.

[0022] Figure 5 This is a schematic diagram of the temperature stages in a graded regeneration technology. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1As shown, this invention provides a circulating formaldehyde adsorption and regeneration system for plywood adhesive application. Its core lies in the combination of an electrostatic-ultrasonic coupled demister, a humidity-adaptive purification adsorption path, an adsorbent performance decay kinetic model, and a multi-source data intelligent control strategy to achieve efficient treatment of formaldehyde waste gas under complex operating conditions. The system includes an anti-interference pretreatment module, a humidity-adaptive analysis module, a saturation monitoring module, a staged desorption and regeneration module, a tail gas treatment module, and a performance decay assessment and compensation module. The anti-interference pretreatment module is connected to the humidity-adaptive analysis module, which is connected to the saturation monitoring module. The saturation monitoring module is connected to the staged desorption and regeneration module. The staged desorption and regeneration module is connected to both the tail gas treatment module and the performance decay assessment and compensation module. The performance decay assessment and compensation module is also connected to the saturation monitoring module.

[0025] The anti-interference pretreatment module uses an electrostatic-ultrasonic coupling demister to treat formaldehyde-containing air and remove paint mist particles.

[0026] Preferably, such as Figure 2 As shown, the electrostatic-ultrasonic coupled demister is the first processing unit of the entire system, mainly composed of an electrostatic dust removal unit, an ultrasonic oscillation unit, and a flow guide channel. The electrostatic dust removal unit is located in the middle of the flow guide channel and contains high-voltage electrodes to generate an electric field, charging the paint mist particles and causing them to deposit on the surface of the dust collection plate. The ultrasonic oscillation unit is installed at the inlet of the flow guide channel; its high-frequency vibration breaks down the agglomeration structure of the paint mist particles, thereby enhancing the electrostatic dust removal effect. The flow guide channel contains honeycomb-shaped guide plates, which are evenly distributed to guide the airflow into a uniform distribution, improving processing efficiency. Formaldehyde-containing air first enters the flow guide channel. Under the action of the ultrasonic oscillation unit, the paint mist particles are dispersed into tiny particles. The airflow then enters the electrostatic dust removal unit, where the charged paint mist particles are deposited on the surface of the dust collection plate under the influence of the electric field. Finally, the treated formaldehyde-containing air is discharged through the outlet of the flow guide channel. This structural design ensures the effective removal of paint mist particles, providing a clean gas environment for formaldehyde adsorption in the subsequent adsorption tower.

[0027] It's important to explain that removing paint mist particles is crucial to prevent them from clogging the pores of the adsorbent and to avoid covering the adsorbent surface, which would reduce its formaldehyde adsorption capacity. Plywood coating workshops often have a high concentration of paint mist particles; if not removed, this will lead to decreased adsorption efficiency and a shortened adsorbent lifespan. Electrostatic-ultrasonic coupled demisters effectively remove paint mist, providing a clean gas environment for subsequent formaldehyde adsorption in the adsorption tower. This ensures a stable and efficient adsorption process and is a vital prerequisite for achieving efficient formaldehyde waste gas treatment under complex operating conditions.

[0028] The humidity adaptive analysis module guides the formaldehyde-containing air, which has undergone the anti-interference pretreatment, through at least one adsorption tower based on the real-time monitored ambient humidity, and outputs purified air.

[0029] Preferably, after anti-interference pretreatment, the formaldehyde-containing air enters the humidity-adaptive purification and adsorption step. For example... Figure 3 As shown, the system includes a first adsorption path and a second adsorption path, which respectively penetrate adsorption regions filled with modified activated carbon adsorbent and hydrophobic zeolite adsorbent. A humidity sensor is installed on the inlet pipe to monitor the relative humidity of the formaldehyde-containing air in real time and generate a humidity signal. After receiving the humidity signal, the control system selectively switches the adsorption path according to the relative humidity. When the relative humidity is less than a preset humidity switching threshold, the control system drives the pipeline valve to introduce the formaldehyde-containing air into the first adsorption path; when the relative humidity is greater than or equal to the humidity switching threshold, the formaldehyde-containing air is introduced into the second adsorption path. This dynamic switching mechanism based on humidity signals fully utilizes the high adsorption capacity of modified activated carbon adsorbent under low humidity conditions and the stability of hydrophobic zeolite adsorbent under high humidity conditions, thereby achieving efficient capture of formaldehyde waste gas under different humidity environments.

[0030] In a preferred embodiment of the present invention, the specific analytical method of guiding and penetrating at least one adsorption tower is as follows: a first adsorption path and a second adsorption path are set, the first adsorption path penetrates the adsorption region filled with modified activated carbon adsorbent, and the second adsorption path penetrates the adsorption region filled with hydrophobic zeolite adsorbent.

[0031] It should be noted that the first adsorption path and the second adsorption path can lead to different areas of the same adsorption tower or different adsorption towers. The humidity adaptive analysis step has at least one first adsorption path or second adsorption path, and during actual humidity adaptive operation, at least one first adsorption path or second adsorption path is connected to the working path.

[0032] A humidity sensor is installed to monitor the relative humidity of the formaldehyde-containing air in real time and generate a humidity signal.

[0033] The control system receives the humidity signal, and when the relative humidity is less than a preset humidity switching threshold, it controls the pipeline valve to introduce the formaldehyde-containing air into the first adsorption path.

[0034] When the relative humidity is greater than or equal to the humidity switching threshold, the pipeline valve is controlled to introduce the formaldehyde-containing air into the second adsorption path.

[0035] One embodiment provides a method for setting a humidity switching threshold, specifically as follows: The adsorption efficiency of modified activated carbon and hydrophobic zeolite for formaldehyde is tested under different relative humidity environments. Starting from a low humidity level, the humidity is gradually increased, and the changes in the efficiency of the two adsorbents are recorded. When the efficiency of the modified activated carbon decreases to the same level as that of the hydrophobic zeolite, this humidity value is the threshold. This threshold needs to be verified through repeated experiments to eliminate random errors and ensure that switching paths at this humidity level optimizes the overall adsorption efficiency of the system, adapts to the characteristics of the two adsorbents, and achieves efficient formaldehyde capture under different humidity conditions.

[0036] The saturation monitoring module collects the formaldehyde concentration at the inlet and outlet of the adsorption tower, calculates the real-time adsorption saturation based on the pre-constructed adsorbent performance decay kinetic model, and compares it with the preset adsorption breakthrough threshold to generate a switching command.

[0037] Preferably, during the adsorption process, saturation monitoring involves real-time acquisition and analysis of formaldehyde concentrations at the inlet and outlet of the adsorption tower, combined with an adsorbent performance decay kinetic model to calculate the real-time adsorption saturation of the adsorbent within the tower. Specifically, inlet and outlet concentration sensors synchronously acquire formaldehyde concentration values, and the constructed adsorbent performance decay kinetic model describes the decay relationship of the total adsorption capacity of the adsorbent with the number of regeneration cycles. Based on the current number of regeneration cycles, the predicted total adsorption capacity for the current cycle is retrieved from the model, and the difference between the inlet and outlet formaldehyde concentrations is integrated over time to obtain the cumulative adsorbed formaldehyde amount. Comparing the cumulative adsorbed formaldehyde amount with the predicted total adsorption capacity for the current cycle yields the real-time adsorption saturation. When the real-time adsorption saturation reaches a preset adsorption breakthrough threshold, the system generates a switching command, disconnecting the adsorption tower from the purification adsorption pipeline and connecting it to the regeneration pipeline.

[0038] In a preferred embodiment of the present invention, the specific method for calculating the real-time adsorption saturation is as follows: using an inlet concentration sensor and an outlet concentration sensor, the inlet formaldehyde concentration value and the outlet formaldehyde concentration value of the adsorption tower are collected synchronously at a preset sampling frequency.

[0039] A kinetic model for the performance degradation of the adsorbent was constructed, which characterizes the degradation relationship of the total adsorption capacity of the adsorbent with the number of regeneration cycles.

[0040] One embodiment provides a method for constructing a kinetic model of adsorbent performance degradation, which includes the following steps: recording the total adsorption capacity data of the adsorbent under different regeneration cycles and establishing a historical performance parameter database; using a preset regression algorithm based on the data to fit a functional relationship between the total adsorption capacity and the number of regeneration cycles, which is the initial model; after each subsequent regeneration, the newly collected performance characterization parameters are added to the database as data points, and the function is refitted to update the model to ensure that it accurately reflects the degradation relationship.

[0041] Based on the current number of regeneration cycles, the predicted total adsorption capacity for the current cycle is obtained from the adsorbent performance decay kinetic model.

[0042] The cumulative amount of adsorbed formaldehyde is obtained by integrating the difference between the imported formaldehyde concentration and the exported formaldehyde concentration over time.

[0043] The real-time adsorption saturation is obtained by comparing the cumulative adsorption amount of formaldehyde with the predicted total adsorption capacity for the current period.

[0044] In a preferred embodiment of the present invention, the specific method for generating the switching command is as follows: when the real-time adsorption saturation is greater than or equal to the preset adsorption penetration threshold, it is determined that a switching operation is required and a switching command is output; otherwise, it is determined that no switching operation is required.

[0045] The adsorption breakthrough threshold is a dynamic variable, whose initial value is set according to the initial performance of the adsorbent and is adjusted after each performance degradation assessment and compensation step.

[0046] One embodiment provides a method for setting the adsorption breakthrough threshold, as follows: the initial value is set based on the initial performance of the adsorbent; it is dynamically adjusted after each performance degradation assessment and compensation. Based on the updated adsorbent performance degradation kinetic model, the performance degradation rate of the next adsorption cycle is predicted, a compensation coefficient is calculated, and the current threshold is multiplied by this coefficient to obtain the adjusted threshold; if the adjusted threshold is lower than the preset minimum safe threshold, it is set as the minimum safe threshold; otherwise, the adjusted value is used. Simultaneously, a switching command is generated by combining the final saturation determination value corrected from multi-source data.

[0047] Specifically, one method for setting a minimum safety threshold is as follows: The same batch of adsorbent is used to fill the adsorption tower. Formaldehyde gas is introduced under simulated actual operating conditions, and the outlet concentration is monitored. When the adsorption saturation gradually increases until the outlet formaldehyde concentration approaches the emission standard, the saturation value at this point is recorded. This experiment is repeated multiple times, and the lower limits of multiple critical values ​​are taken as the initial minimum safety threshold. Combining the adsorbent performance degradation law, the above experiment is repeated at different regeneration cycles to dynamically adjust the threshold, ensuring that even if the adsorbent performance degrades, the risk of formaldehyde leakage exceeding the standard can still be avoided.

[0048] In a preferred embodiment of the present invention, the system further includes an intelligent control strategy based on multi-source data, the strategy specifically including: in addition to the formaldehyde concentration data, the bed temperature data and pressure drop data in the adsorption tower are also collected simultaneously.

[0049] A correlation model is established to describe the nonlinear relationship between the outlet formaldehyde concentration, the bed temperature, the pressure drop, and the actual working state of the adsorbent.

[0050] The real-time collected formaldehyde concentration data, bed temperature data, and pressure drop data are input into the correlation model, and the correction value for the real-time adsorption saturation is output.

[0051] The correction value is applied to the real-time adsorption saturation calculated by the pre-constructed adsorbent performance decay kinetic model to obtain a final saturation determination value, and the switching command is generated based on the final saturation determination value.

[0052] It should be noted that the bed temperature changes with the thermal effect during adsorption. The heat of adsorption released during formaldehyde adsorption causes the temperature to rise. When the adsorbent's performance declines or approaches saturation, the temperature change trend will become abnormal, reflecting the actual active state of the adsorbent. The pressure drop is related to the degree of pore blockage in the adsorbent. When paint mist residue or adsorbent aging leads to a reduction in pore size, the pressure drop will change significantly, reflecting the physical structure of the adsorbent. These two factors, along with formaldehyde concentration, constitute multi-source information. Through correlation models, the limitations of single concentration data can be overcome, providing a more comprehensive reflection of the adsorbent's actual working state. This allows for accurate correction of real-time adsorption saturation and improves the reliability of switching commands.

[0053] The staged desorption and regeneration module, according to the switching command, cuts off the self-purification adsorption pipeline of the saturated adsorption tower and connects it to the regeneration pipeline, introduces the regeneration medium into the saturated adsorption tower and heats it to form a high-concentration formaldehyde mixed gas.

[0054] Preferably, the desorption and regeneration step employs a staged regeneration technology, specifically comprising two stages. For example... Figure 5 As shown, in the first heating and desorption stage, a regeneration medium at a first temperature is introduced into the adsorption tower. This first temperature is set above the desorption temperature of water molecules and below the desorption temperature of formaldehyde molecules, prioritizing the desorption and removal of water molecules adsorbed on the adsorbent. After completing the first heating and desorption stage, the second heating and desorption stage begins, introducing a regeneration medium at a second temperature, set above the desorption temperature of formaldehyde molecules. This desorbs the formaldehyde molecules adsorbed by the adsorbent, forming a high-concentration formaldehyde mixture. This staged regeneration technology not only optimizes energy utilization efficiency but also avoids the thermal damage to the adsorbent caused by a single high-temperature desorption process.

[0055] In a preferred embodiment of the present invention, the specific analytical process of the graded desorption and regeneration is as follows: In the first heating and desorption stage, a regeneration medium at a first temperature is introduced into the adsorption tower. The first temperature is set above the desorption temperature of water molecules and below the desorption temperature of formaldehyde molecules, so as to preferentially desorb and remove water molecules adsorbed on the adsorbent.

[0056] It should be explained that in the first heating and desorption stage, a regeneration medium with a temperature above the desorption temperature of water molecules and below the desorption temperature of formaldehyde molecules is introduced into the adsorption tower. This temperature setting can specifically desorb and remove water molecules adsorbed on the surface of the adsorbent without triggering formaldehyde desorption, thus avoiding the energy waste of the regeneration medium caused by the simultaneous desorption of water and formaldehyde molecules, and reducing the interference of residual water molecules on the subsequent adsorption process.

[0057] The second heating and desorption stage, after the first stage is completed, introduces a regeneration medium with a temperature higher than the formaldehyde molecule desorption temperature. This high-temperature environment efficiently desorbs formaldehyde molecules adsorbed in the pores of the adsorbent, forming a high-concentration formaldehyde mixture, which facilitates subsequent exhaust gas treatment.

[0058] In the second heating and desorption stage, after the first heating and desorption stage is completed, a regeneration medium at a second temperature is introduced into the adsorption tower. This second temperature is set above the desorption temperature of formaldehyde molecules to desorb the formaldehyde molecules adsorbed by the adsorbent and form the high-concentration formaldehyde mixed gas.

[0059] The exhaust gas treatment module introduces the high-concentration formaldehyde mixed gas into the catalytic oxidation reactor to oxidize and decompose the formaldehyde in it.

[0060] It should be noted that exhaust gas treatment is the final stage of processing the high-concentration formaldehyde mixture generated by staged desorption and regeneration. This mixture is introduced into a catalytic oxidation reactor, where a catalyst, such as a precious metal or metal oxide catalyst, reacts with oxygen under specific temperature conditions, oxidizing and decomposing the formaldehyde into harmless carbon dioxide and water. This process completely eliminates the toxicity of formaldehyde, avoids secondary pollution caused by direct emissions of high-concentration formaldehyde, meets environmental emission standards, achieves the harmless treatment of formaldehyde waste gas, and ensures the safety of the surrounding environment.

[0061] The performance degradation assessment and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance degradation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the staged desorption and regeneration steps accordingly to compensate for performance degradation.

[0062] Preferably, after each desorption and regeneration, a performance degradation assessment and compensation step collects characterization parameters for the regenerated performance of the adsorption tower. The specific process includes introducing a standard formaldehyde test gas of a specific concentration into the regenerated adsorption tower, continuously monitoring the formaldehyde concentration at the outlet of the adsorption tower, and recording the time from the introduction of the test gas until the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration, which is used as the dynamic adsorption capacity characteristic parameter for this regeneration. Simultaneously, the specific surface area and pore volume of the regenerated adsorbent are measured using nitrogen adsorption, which are used as the physical structure characteristic parameters for this regeneration. The dynamic adsorption capacity characteristic parameters and the physical structure characteristic parameters are used together as post-regeneration performance characterization parameters to update the adsorbent performance degradation kinetic model. Figure 4 As shown, the update process includes adding the collected post-regeneration performance characterization parameters as new data points to the historical performance parameter database, fitting the historical performance parameter database containing the new data points using a preset regression algorithm, and generating an updated function as the updated adsorbent performance decay kinetic model.

[0063] In a preferred embodiment of the present invention, the specific analysis method of the regenerated performance characterization parameters is as follows: after the staged desorption and regeneration module is completed, a standard formaldehyde test gas of a specific concentration is introduced into the adsorption tower that has completed desorption and regeneration.

[0064] The formaldehyde concentration at the outlet of the adsorption tower is continuously monitored, and the time from the introduction of the test gas to the time when the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration is recorded. This time is used as the dynamic adsorption capacity characteristic parameter for this regeneration.

[0065] The specific surface area and pore volume of the adsorbent after staged desorption and regeneration in the adsorption tower were measured using the nitrogen adsorption method, and were used as the physical structural characteristic parameters of this regeneration.

[0066] The dynamic adsorption capacity characteristic parameter and the physical structure characteristic parameter are used together as the performance characterization parameter after regeneration.

[0067] In a preferred embodiment of the present invention, the specific method for updating the adsorbent performance decay kinetic model is as follows: the collected post-regeneration performance characterization parameters are added to the historical performance parameter database as a new data point.

[0068] The kinetic model for adsorbent performance degradation is a function that maps the number of regeneration cycles to adsorbent performance parameters.

[0069] A preset regression algorithm is used to fit the historical performance parameter database containing the new data points to generate the updated function, which serves as the updated kinetic model for adsorbent performance degradation.

[0070] In a preferred embodiment of the present invention, the specific method for dynamically adjusting the adsorption breakthrough threshold is as follows: based on the updated adsorbent performance decay kinetic model, the adsorbent performance decay rate for the next adsorption cycle is predicted.

[0071] A compensation coefficient is calculated based on the predicted performance degradation rate.

[0072] The adsorption penetration threshold of the current period is multiplied by the compensation coefficient to obtain an adjusted adsorption penetration threshold.

[0073] If the adjusted adsorption breakthrough threshold is lower than the preset minimum safety threshold, then the adsorption breakthrough threshold for the next adsorption cycle is set to the minimum safety threshold. Otherwise, it is set to the adjusted adsorption breakthrough threshold.

[0074] In a preferred embodiment of the present invention, the specific adjustment method of the process parameters of the staged desorption and regeneration step is as follows: the regenerated performance characterization parameters are compared with the regenerated performance characterization parameters of the previous cycle, and the regeneration efficiency recovery degree is calculated.

[0075] Preferably, a method for calculating the regeneration efficiency recovery degree is as follows: Based on the performance characterization parameters after regeneration, select dynamic adsorption capacity characteristic parameters, such as the time it takes for the outlet concentration to reach the breakthrough point, and physical structure characteristic parameters, such as specific surface area and pore volume. Calculate the ratio of each parameter after the current regeneration cycle to the corresponding parameter after the previous regeneration cycle, and take the average of these ratios as the regeneration efficiency recovery degree. This value reflects the degree to which the regeneration process restores the adsorbent performance and is used to determine whether the regeneration process parameters need to be adjusted.

[0076] If the regeneration efficiency recovery is lower than the preset regeneration efficiency target value, then in the next regeneration cycle, the temperature of the regeneration medium in the desorption and regeneration step will be increased or its action time will be extended.

[0077] One embodiment provides a method for setting a regeneration efficiency target value: using the initial performance parameters of the adsorbent as a benchmark, the dynamic adsorption capacity characteristic parameters and physical structure characteristic parameters of the new adsorbent are taken as reference values. A certain percentage of the reference values ​​is set as the initial regeneration efficiency target value, the percentage being determined according to environmental standards and economic considerations. Subsequently, as the adsorbent performance decays, combined with an updated adsorbent performance decay kinetic model, the theoretical recovery upper limit for the next cycle is predicted, and the corresponding percentage is used as the adjusted target value, ensuring that the target value is both feasible and guarantees efficient system operation.

[0078] It should be explained that increasing the temperature of the regeneration medium or extending its reaction time in the desorption-regeneration step is to improve the regeneration effect of the adsorbent. Increased temperature enhances molecular thermal motion, making it easier for residual formaldehyde in the adsorbent pores to detach from the adsorption sites; extending the reaction time allows for sufficient contact between the regeneration medium and the adsorbent, ensuring that more formaldehyde is desorbed. Both methods compensate for the decrease in adsorbent activity caused by multiple regenerations by strengthening the mass transfer and heat exchange processes, improving the recovery of regeneration efficiency, bringing the adsorbent performance closer to the target value, and ensuring the stability of subsequent adsorption processes.

[0079] The adjustment amount of the process parameters is associated with the difference between the regeneration efficiency recovery degree and the regeneration efficiency target value through a preset mapping relationship.

[0080] Preferably, one method for setting the mapping relationship is as follows: The optimal process parameter adjustment amount, such as temperature increase or time extension, corresponding to the difference between different regeneration efficiency recovery degrees and the target value is obtained experimentally, and a difference-adjustment amount dataset is established. Using linear fitting or piecewise function methods, the difference is divided into several intervals, and a corresponding adjustment amount is matched to each interval. The larger the difference, the larger the adjustment amount, forming a preset mapping relationship. For example, when the difference is 10%, the temperature is increased by 5℃; when the difference is 20%, it is increased by 12℃. This information is written into the control system. During regeneration, the corresponding adjustment amount is called based on the real-time difference to achieve precise parameter control.

[0081] Furthermore, the optimal process parameter adjustment refers to the optimal adjustment range of the regeneration medium temperature or action time required in staged desorption and regeneration to achieve the target regeneration efficiency recovery. For example, when the regeneration efficiency recovery is lower than the target value, by experimentally testing the regeneration effect corresponding to different temperature increases or time extensions, the adjustment value that achieves the target recovery while minimizing energy consumption can be selected. This value is the optimal process parameter adjustment range at this time, balancing regeneration efficiency and economy.

[0082] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, and all such modifications and additions should fall within the protection scope of the present invention.

Claims

1. A circulating formaldehyde adsorption and regeneration system for plywood adhesive application, characterized in that, include: The anti-interference pretreatment module uses an electrostatic-ultrasonic coupling demister to treat formaldehyde-containing air and remove paint mist particles. The humidity adaptive analysis module, based on real-time monitoring of ambient humidity, guides the formaldehyde-containing air that has undergone the anti-interference pretreatment and passes through at least one adsorption tower to output purified air. The saturation monitoring module collects the formaldehyde concentration at the inlet and outlet of the adsorption tower, calculates the real-time adsorption saturation based on the pre-constructed adsorbent performance decay kinetic model, and compares it with the preset adsorption breakthrough threshold to generate a switching command. The staged desorption and regeneration module, according to the switching command, cuts off the self-purification adsorption pipeline of the saturated adsorption tower and connects it to the regeneration pipeline, introduces the regeneration medium into the saturated adsorption tower and heats it to form a high-concentration formaldehyde mixed gas. The exhaust gas treatment module introduces the high-concentration formaldehyde mixed gas into a catalytic oxidation reactor to oxidize and decompose the formaldehyde in it. The performance degradation assessment and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance degradation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the staged desorption and regeneration steps accordingly to compensate for performance degradation. The specific analysis method for the regenerated performance characterization parameters is as follows: After the staged desorption and regeneration module is completed, a standard formaldehyde test gas of a specific concentration is introduced into the adsorption tower that has completed desorption and regeneration. The formaldehyde concentration at the outlet of the adsorption tower is continuously monitored, and the time from the introduction of the test gas to the time when the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration is recorded. This time is used as the dynamic adsorption capacity characteristic parameter for this regeneration. The specific surface area and pore volume of the adsorbent after staged desorption and regeneration in the adsorption tower were measured by nitrogen adsorption method and used as the physical structural characteristic parameters of this regeneration. The dynamic adsorption capacity characteristic parameter and the physical structure characteristic parameter are used together as the performance characterization parameter after regeneration. The specific method for updating the kinetic model of adsorbent performance degradation is as follows: The collected post-regeneration performance characterization parameters are added to the historical performance parameter database as a new data point. The kinetic model for adsorbent performance degradation is a function that maps the number of regeneration cycles to adsorbent performance parameters; A preset regression algorithm is used to fit the historical performance parameter database containing the new data points to generate the updated function, which serves as the updated adsorbent performance decay kinetic model. The specific method for dynamically adjusting the adsorption penetration threshold is as follows: Based on the updated kinetic model of adsorbent performance degradation, the adsorbent performance degradation rate for the next adsorption cycle is predicted. Calculate a compensation coefficient based on the predicted performance degradation rate; Multiply the current adsorption penetration threshold by the compensation coefficient to obtain an adjusted adsorption penetration threshold. If the adjusted adsorption penetration threshold is lower than the preset minimum safety threshold, the adsorption penetration threshold for the next adsorption cycle is set to the minimum safety threshold; otherwise, it is set to the adjusted adsorption penetration threshold.

2. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The specific analytical method for guiding and penetrating at least one adsorption tower is as follows: A first adsorption path and a second adsorption path are provided. The first adsorption path passes through the adsorption region filled with modified activated carbon adsorbent, and the second adsorption path passes through the adsorption region filled with hydrophobic zeolite adsorbent. A humidity sensor is installed to monitor the relative humidity of the formaldehyde-containing air in real time and generate a humidity signal. The control system receives the humidity signal, and when the relative humidity is less than the preset humidity switching threshold, it controls the pipeline valve to introduce the formaldehyde-containing air into the first adsorption path. When the relative humidity is greater than or equal to the humidity switching threshold, the pipeline valve is controlled to introduce the formaldehyde-containing air into the second adsorption path.

3. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The specific method for calculating real-time adsorption saturation is as follows: The formaldehyde concentration values ​​at the inlet and outlet of the adsorption tower are collected synchronously at a preset sampling frequency using inlet and outlet concentration sensors. A kinetic model for the performance degradation of the adsorbent was constructed, which characterizes the degradation relationship of the total adsorption capacity of the adsorbent with the number of regeneration cycles. Based on the current number of regeneration cycles, the predicted total adsorption capacity for the current cycle is obtained from the adsorbent performance decay kinetic model. The difference between the inlet formaldehyde concentration and the outlet formaldehyde concentration is integrated over time to obtain the cumulative amount of adsorbed formaldehyde. The real-time adsorption saturation is obtained by comparing the cumulative adsorption amount of formaldehyde with the predicted total adsorption capacity for the current period.

4. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The specific method for generating the switching instruction is as follows: When the real-time adsorption saturation is greater than or equal to the preset adsorption penetration threshold, it is determined that a switching operation is required and a switching command is output; otherwise, it is determined that no switching operation is required. The adsorption breakthrough threshold is a dynamic variable, whose initial value is set according to the initial performance of the adsorbent and is adjusted after each performance degradation assessment and compensation step.

5. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The specific analysis process of the staged desorption and regeneration is as follows: In the first heating and desorption stage, a regeneration medium at a first temperature is introduced into the adsorption tower. This first temperature is set above the desorption temperature of water molecules and below the desorption temperature of formaldehyde molecules, in order to preferentially desorb and remove water molecules adsorbed on the adsorbent. In the second heating and desorption stage, after the first heating and desorption stage is completed, a regeneration medium at a second temperature is introduced into the adsorption tower. This second temperature is set above the desorption temperature of formaldehyde molecules to desorb the formaldehyde molecules adsorbed by the adsorbent and form the high-concentration formaldehyde mixed gas.

6. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The specific adjustment methods for the process parameters of the staged desorption and regeneration step are as follows: The regeneration efficiency recovery rate is calculated by comparing the regeneration performance characterization parameters with those of the previous cycle. If the regeneration efficiency recovery is lower than the preset regeneration efficiency target value, then in the next regeneration cycle, the temperature of the regeneration medium in the desorption and regeneration step will be increased or its action time will be extended. The adjustment amount of the process parameters is associated with the difference between the regeneration efficiency recovery degree and the regeneration efficiency target value through a preset mapping relationship.

7. The circulating formaldehyde adsorption and regeneration system for plywood adhesive application as described in claim 1, characterized in that: The system also includes an intelligent control strategy based on multi-source data, the strategy specifically including: In addition to the formaldehyde concentration data, the bed temperature data and pressure drop data inside the adsorption tower were also collected simultaneously. A correlation model is established to describe the nonlinear relationship between the outlet formaldehyde concentration, the bed temperature, the pressure drop, and the actual working state of the adsorbent. The real-time collected formaldehyde concentration data, bed temperature data, and pressure drop data are input into the correlation model, and the correction value for the real-time adsorption saturation is output. The correction value is applied to the real-time adsorption saturation calculated by the pre-constructed adsorbent performance decay kinetic model to obtain a final saturation determination value, and the switching command is generated based on the final saturation determination value.

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