Circulating formaldehyde adsorption regeneration system for plywood gluing

Abstract

The invention 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 electrostatic-ultrasonic coupling demister and a humidity self-adaptive purification adsorption path are introduced, so that the problem that the efficiency of a traditional adsorption process is reduced under the conditions of paint mist particle interference and humidity fluctuation is solved, and the adaptability to complex working conditions is improved; an adsorbent performance attenuation kinetic model and a multi-source data intelligent control strategy are established, accurate monitoring of adsorption saturation and dynamic adjustment of an adsorption penetration threshold value and regeneration process parameters are achieved, and the problem that the treatment effect is reduced due to adsorbent performance attenuation is solved; through the design of the grading regeneration technology and the tail gas catalytic oxidation device, the energy utilization efficiency in the adsorbent regeneration process is optimized, high-concentration formaldehyde mixed gas is thoroughly decomposed into harmless substances, and the risk of secondary pollution is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of formaldehyde waste gas treatment for plywood gluing, and relates to a circulating formaldehyde adsorption and regeneration system for plywood gluing. Background Art

[0002] Formaldehyde waste gas generated during the plywood gluing process is a common source of industrial pollution, and its treatment is of great significance for safeguarding the production environment and surrounding ecological security. Currently, the main treatment methods for formaldehyde-containing waste gas 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 high concentrations 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-laden air. These methods often rely on fixed adsorption cycles and regeneration conditions, and monitor the formaldehyde concentration at the outlet to determine adsorption saturation. Some improved processes have introduced simple humidity control measures, such as adding a dehumidifier to the air intake line, but these measures are difficult to fully adapt to complex and changing actual operating conditions. Furthermore, existing technologies primarily rely on empirical data to assess adsorbent performance degradation and lack dynamic adjustment mechanisms, resulting in an increased risk of adsorption breakthrough and decreased regeneration efficiency.

[0004] The aforementioned technical approaches exhibit certain shortcomings when addressing formaldehyde waste gas generated during the plywood gluing process. Due to the large humidity fluctuations in the gluing workshop and the frequent presence of paint mist particles, traditional methods are prone to reduced treatment effectiveness due to adsorbent surface clogging or competitive adsorption by water molecules. Furthermore, the phenomenon of gradual attenuation of adsorbent performance with the number of regeneration cycles has not been adequately addressed, and effective compensation strategies are lacking. Monitoring methods primarily focus on formaldehyde concentration data, failing to comprehensively consider multiple sources of information, such as temperature and pressure. This results in inaccurate adsorption saturation determinations, impacting the stability and economic efficiency of system operation. Summary of the Invention

[0005] In view of this, in order to solve the problems raised in the above background technology, a circulating formaldehyde adsorption and regeneration system for plywood gluing is proposed.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A circulating formaldehyde adsorption regeneration system for plywood gluing, 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 that has undergone the anti-interference pretreatment to pass 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 a pre-built adsorbent performance decay kinetic model, and compares it with a preset adsorption penetration threshold to generate a switching instruction.

[0009] The graded desorption regeneration module cuts out the saturated adsorption tower from the purification adsorption pipeline according to the switching instruction 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 tail gas treatment module introduces the high-concentration formaldehyde mixed gas into a catalytic oxidation reactor to oxidize and decompose the formaldehyde therein.

[0011] The performance attenuation evaluation and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance attenuation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the graded desorption regeneration step to compensate for the performance attenuation.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention removes paint mist particles by anti-interference pretreatment and utilizes an electrostatic-ultrasonic coupling demister, thereby avoiding the clogging of the adsorbent pores by the paint mist, effectively protecting the adsorbent, improving its adsorption efficiency and service life, and ensuring the stability of the subsequent adsorption process.

[0013] Based on humidity adaptive analysis, the present invention sets up two paths filled with modified activated carbon and hydrophobic zeolite adsorbent respectively. According to the humidity switching, there are suitable adsorbents in different humidity environments to play a high-efficiency adsorption role, ensuring the stability of the formaldehyde adsorption effect.

[0014] The present invention calculates the real-time adsorption saturation based on the adsorbent performance attenuation kinetic model through saturation monitoring, generates switching instructions in combination with preset thresholds, and realizes accurate judgment of regeneration timing, avoids energy waste and formaldehyde leakage, and improves the economy and reliability of the system.

[0015] The present invention adopts graded desorption regeneration, first decomposing water molecules at a specific temperature and then decomposing formaldehyde molecules at a higher temperature, thereby improving desorption efficiency, reducing the impact of residual water molecules on subsequent adsorption, and at the same time reducing energy consumption and improving regeneration effect.

[0016] The present invention evaluates and compensates for performance attenuation, updates the adsorbent performance attenuation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or regeneration process parameters, thereby effectively compensating for the impact of adsorbent performance attenuation and ensuring long-term stable and efficient operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

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

[0021] Figure 4 Flowchart for the update of the kinetic model for adsorbent performance decay.

[0022] Figure 5 Schematic diagram of the temperature stages of the graded regeneration technology. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] See also Figure 1As shown, the present invention provides a circulating formaldehyde adsorption and regeneration system for plywood gluing. Its core lies in the combination of an electrostatic-ultrasonic coupling 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 working conditions. The system includes an anti-interference pretreatment module, a humidity-adaptive analysis module, a saturation monitoring module, a staged desorption and regeneration module, an exhaust 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, which is connected to the staged desorption and regeneration module, which is connected to the exhaust gas treatment module and the performance decay assessment and compensation module, respectively, and the performance decay assessment and compensation module is 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, if Figure 2 As shown, the electrostatic-ultrasonic coupled mist eliminator is the first treatment unit in the entire system. It primarily consists of an electrostatic precipitator unit, an ultrasonic oscillator unit, and a guide channel. The electrostatic precipitator unit is located in the central region of the guide channel. High-voltage electrodes are installed within it to generate an electric field, charging paint mist particles and depositing them on the surface of the dust collecting plate. The ultrasonic oscillator unit is installed at the entrance of the guide channel. Its high-frequency vibration disrupts the agglomeration of paint mist particles, thereby enhancing the electrostatic precipitator effect. The guide channel is equipped with honeycomb-shaped guide plates, which are evenly distributed throughout the guide channel to guide the airflow into a uniform state, thereby improving treatment efficiency. Formaldehyde-containing air first enters the guide channel. The ultrasonic oscillator unit disperses the paint mist particles into tiny particles. The air then enters the electrostatic precipitator unit. The charged paint mist particles are deposited on the surface of the dust collecting plate under the influence of the electric field. The treated formaldehyde-containing air is finally discharged through the guide channel outlet. This structural design ensures the effective removal of paint mist particles and provides a clean air environment for subsequent formaldehyde adsorption in the adsorption tower.

[0027] It's important to explain that paint mist particles are removed to prevent them from clogging the adsorbent's pores and coating the adsorbent's surface, which would reduce its formaldehyde adsorption capacity. Plywood gluing workshops are prone to paint mist particles. Failure to remove them can lead to reduced adsorption efficiency and shortened adsorbent life. Electrostatic-ultrasonic coupled mist eliminators effectively remove paint mist, providing a clean air environment for subsequent formaldehyde adsorption in the adsorption tower. This ensures a stable and efficient adsorption process and is a crucial prerequisite for efficient formaldehyde waste gas treatment under complex operating conditions.

[0028] The humidity adaptive analysis module guides the formaldehyde-containing air that has undergone the anti-interference pretreatment to pass 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 adsorption step. Figure 3 As shown, it includes a first adsorption path and a second adsorption path, which respectively pass through the adsorption area filled with modified activated carbon adsorbent and hydrophobic zeolite adsorbent. A humidity sensor is installed in the intake 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 the preset humidity switching threshold, the control system drives the pipeline valve to direct 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 directed into the second adsorption path. This dynamic switching mechanism based on humidity signals fully utilizes the high adsorption capacity of the modified activated carbon adsorbent under low humidity conditions and the stability of the hydrophobic zeolite adsorbent under high humidity conditions, thereby achieving efficient capture of formaldehyde exhaust gas under different humidity environments.

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

[0031] It should be noted that the first adsorption path and the second adsorption path can be directed 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. When the actual humidity adaptive operation is performed, at least one first adsorption path or second adsorption path is connected to the working path.

[0032] A humidity sensor is provided 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 the preset humidity switching threshold, the control pipeline valve is controlled 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.

[0034] One embodiment provides a method for setting a humidity switching threshold, specifically as follows: The formaldehyde adsorption efficiency of modified activated carbon and hydrophobic zeolite is tested separately under different relative humidity environments. Starting from a low humidity, 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 drops to the same level as the efficiency of the hydrophobic zeolite, this humidity value is the threshold. This threshold is verified through repeated experiments to eliminate accidental errors and ensure that the switching path at this humidity optimizes the overall adsorption efficiency of the system, adapts to the characteristics of the two adsorbents, and achieves efficient formaldehyde capture at different humidity levels.

[0035] 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 a pre-built adsorbent performance decay kinetic model, and compares it with a preset adsorption penetration threshold to generate a switching instruction.

[0036] Preferably, during the adsorption process, the saturation monitoring is performed by collecting and analyzing the formaldehyde concentrations at the inlet and outlet of the adsorption tower in real time, and combining the adsorbent performance decay kinetic model to calculate the real-time adsorption saturation of the adsorbent in the adsorption tower. Specifically, the inlet concentration sensor and the outlet concentration sensor synchronously collect 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. According to the current number of regeneration cycles, the predicted total adsorption capacity of the current cycle is queried from the model, and the difference between the inlet formaldehyde concentration value and the outlet formaldehyde concentration value is time-integrated to obtain the cumulative amount of adsorbed formaldehyde. The cumulative amount of adsorbed formaldehyde is compared with the predicted total adsorption capacity of the current cycle to obtain the real-time adsorption saturation. When the real-time adsorption saturation reaches the preset adsorption penetration threshold, the system generates a switching instruction to cut the adsorption tower out of the purification adsorption pipeline and connect it to the regeneration pipeline.

[0037] In a preferred embodiment of the present invention, the specific method of calculating the real-time adsorption saturation is as follows: using an inlet concentration sensor and an outlet concentration sensor to synchronously collect the inlet formaldehyde concentration value and the outlet formaldehyde concentration value of the adsorption tower at a preset sampling frequency.

[0038] A kinetic model of the adsorbent performance decay is constructed, and the model characterizes the decay relationship of the total adsorption capacity of the adsorbent as the number of regeneration cycles changes.

[0039] In one embodiment, a method and steps for constructing a kinetic model of adsorbent performance attenuation are provided, which are specifically as follows: recording the total adsorption capacity data of the adsorbent under different regeneration cycles to establish a historical performance parameter database; using a preset regression algorithm based on the data, fitting a functional relationship between the total adsorption capacity and the number of regeneration cycles, and this function 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 attenuation relationship.

[0040] According to the current number of regeneration cycles, the predicted total adsorption capacity of the current cycle is obtained from the adsorbent performance decay kinetic model.

[0041] The difference between the inlet formaldehyde concentration value and the outlet formaldehyde concentration value is time-integrated to obtain the cumulative amount of adsorbed formaldehyde.

[0042] The cumulative adsorbed formaldehyde amount is compared with the predicted total adsorption capacity of the current cycle to obtain the real-time adsorption saturation.

[0043] In a preferred embodiment of the present invention, the specific method of 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 instruction is output; otherwise, it is determined that no switching operation is required.

[0044] The adsorption breakthrough threshold is a dynamic variable, the initial value of which is set according to the initial performance of the adsorbent and is adjusted after each performance decay evaluation and compensation step.

[0045] One embodiment provides a method for setting an adsorption breakthrough threshold, specifically as follows: an initial value is set based on the initial adsorbent performance; after each performance decay assessment and compensation, dynamic adjustment is performed. Based on an updated adsorbent performance decay kinetic model, the performance decay rate for the next adsorption cycle is predicted, a compensation coefficient is calculated, and the current threshold is multiplied by the coefficient to obtain the adjusted threshold; if the adjusted threshold is lower than the preset minimum safety threshold, the minimum safety threshold is set; otherwise, the adjusted value is used. A switching instruction is also generated by combining the final saturation determination value corrected by multi-source data.

[0046] Specifically, one method for presetting the minimum safety threshold involves filling an adsorption tower with adsorbent from the same batch, introducing formaldehyde gas to simulate actual operating conditions, and monitoring the outlet concentration. When the adsorption saturation gradually increases to a point where the outlet formaldehyde concentration approaches the emission standard, the saturation value at that point is recorded. The experiment is repeated multiple times, and the lower limit of each set of critical values ​​is used as the initial minimum safety threshold. Based on the deterioration pattern of the adsorbent performance, this experiment is repeated at different regeneration cycles, dynamically adjusting the threshold to ensure that even with adsorbent performance degradation, the risk of formaldehyde leakage exceeding the standard is avoided.

[0047] In a preferred embodiment of the present invention, the system further includes an intelligent control strategy based on multi-source data, and the strategy specifically includes: in addition to the formaldehyde concentration data, the bed temperature data and pressure drop data in the adsorption tower are also synchronously collected.

[0048] A correlation model is established, which describes the nonlinear relationship between the outlet formaldehyde concentration, the bed temperature, the pressure drop and the actual working state of the adsorbent.

[0049] The formaldehyde concentration data, the bed temperature data and the pressure drop data collected in real time are input into the correlation model, and a correction value of the real-time adsorption saturation is output.

[0050] The correction value is applied to the real-time adsorption saturation calculated by a pre-built adsorbent performance decay kinetic model to obtain a final saturation determination value, and the switching instruction is generated based on the final saturation determination value.

[0051] It's important to note that the bed temperature varies with the thermal effects of the adsorption process. The heat of adsorption released during formaldehyde adsorption causes the temperature to rise. When the adsorbent's performance declines or approaches saturation, the temperature trend becomes abnormal, reflecting the adsorbent's actual activity. Pressure drop is related to the degree of adsorbent pore blockage. When paint mist residue or adsorbent aging reduces pore size, the pressure drop changes significantly, reflecting the adsorbent's physical structure. Together with formaldehyde concentration, these two data sources constitute multi-source information. Correlation models can overcome the limitations of single-concentration data and more comprehensively reflect the adsorbent's actual operating state, accurately correcting real-time adsorption saturation and improving the reliability of switching instructions.

[0052] The graded desorption regeneration module cuts out the saturated adsorption tower from the purification adsorption pipeline according to the switching instruction 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.

[0053] Preferably, the desorption regeneration step adopts a graded regeneration technology, which specifically includes two stages. Figure 5 As shown, in the first temperature rise and decomposition stage, a regeneration medium at a first temperature is introduced into the adsorption tower. The first temperature is set above the decomposition temperature of water molecules and below the decomposition temperature of formaldehyde molecules. Water molecules adsorbed on the adsorbent are preferentially decomposed and removed. After the first temperature rise and decomposition stage is completed, the second temperature rise and decomposition stage begins. A regeneration medium at a second temperature is introduced into the adsorption tower. The second temperature is set above the decomposition temperature of formaldehyde molecules. Formaldehyde molecules adsorbed by the adsorbent are decomposed to form a high-concentration formaldehyde mixed gas. This graded regeneration technology not only optimizes energy utilization efficiency, but also avoids the problem of thermal damage to the adsorbent caused by a one-time high-temperature decomposition.

[0054] In a preferred embodiment of the present invention, the specific analysis process of the graded desorption regeneration is as follows: in the first temperature rise and decomposition stage, a regeneration medium of a first temperature is introduced into the adsorption tower. The first temperature is set to be above the decomposition temperature point of water molecules and below the decomposition temperature point of formaldehyde molecules, so as to preferentially decompose and remove the water molecules adsorbed on the adsorbent.

[0055] It's important to explain that during the first heating and desorption phase, a regeneration medium is introduced into the adsorption tower at a temperature above the desorption point for water molecules but below the desorption point for formaldehyde molecules. This temperature setting specifically desorbs and removes water molecules adsorbed on the adsorbent surface without triggering formaldehyde desorption. This avoids the wasteful regeneration medium energy consumption caused by the simultaneous desorption of both water and formaldehyde molecules, and also reduces the interference of residual water molecules with subsequent adsorption processes.

[0056] After the first stage is complete, the second heating and desorption phase introduces a regeneration medium with a temperature higher than the desorption temperature of formaldehyde molecules. This high temperature environment efficiently desorbs formaldehyde molecules adsorbed in the pores of the adsorbent, forming a high-concentration formaldehyde mixed gas that facilitates subsequent exhaust gas disposal.

[0057] In the second temperature rise and decomposition stage, after completing the first temperature rise and decomposition stage, a regeneration medium at a second temperature is introduced into the adsorption tower. The second temperature is set to be above the decomposition temperature point of the formaldehyde molecules to decompose the formaldehyde molecules adsorbed by the adsorbent to form the high-concentration formaldehyde mixed gas.

[0058] The tail gas treatment module introduces the high-concentration formaldehyde mixed gas into a catalytic oxidation reactor to oxidize and decompose the formaldehyde therein.

[0059] It's important to note that tail gas treatment is the final step in treating the high-concentration formaldehyde mixed gas produced by graded desorption and regeneration. This mixed gas is introduced into a catalytic oxidation reactor. Using a catalyst within the reactor, such as a precious metal or metal oxide catalyst, under certain temperature conditions, the formaldehyde reacts with oxygen, oxidizing it into harmless carbon dioxide and water. This process completely eliminates formaldehyde toxicity and prevents secondary pollution caused by direct discharge of high-concentration formaldehyde. This not only meets environmental emission standards, but also ensures the harmless treatment of formaldehyde waste gas and protects the surrounding environment.

[0060] The performance attenuation evaluation and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance attenuation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the graded desorption regeneration step to compensate for the performance attenuation.

[0061] Preferably, after each desorption regeneration is completed, the performance attenuation evaluation and compensation step collects characterization parameters for the post-regeneration 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 to the time when the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration, as the dynamic adsorption capacity characteristic parameter of this regeneration. At the same time, the nitrogen adsorption method is used to measure the specific surface area and pore volume of the regenerated adsorbent as the physical structure characteristic parameters of this regeneration. The dynamic adsorption capacity characteristic parameters and the physical structure characteristic parameters are used together as the post-regeneration performance characterization parameters to update the adsorbent performance attenuation kinetic model. Figure 4 As shown, the updating process includes adding the collected post-regeneration performance characterization parameters as a new data point to the historical performance parameter database, using a preset regression algorithm to fit the historical performance parameter database containing the new data point, and generating an updated function as the updated adsorbent performance decay kinetic model.

[0062] In a preferred embodiment of the present invention, the specific analysis method of the performance characterization parameters after regeneration is as follows: after the staged desorption regeneration module is completed, a standard formaldehyde test gas of a specific concentration is introduced into the adsorption tower that has completed desorption regeneration.

[0063] The formaldehyde concentration at the outlet of the adsorption tower is continuously monitored, and the time from the start of the introduction of the test gas to the time when the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration is recorded, and this time is used as the dynamic adsorption capacity characteristic parameter of this regeneration.

[0064] The nitrogen adsorption method was used to measure the specific surface area and pore volume of the adsorbent after the corresponding graded desorption regeneration in the adsorption tower, which were used as the physical structure characteristic parameters of this regeneration.

[0065] The dynamic adsorption capacity characteristic parameter and the physical structure characteristic parameter are used together as the post-regeneration performance characterization parameter.

[0066] In a preferred embodiment of the present invention, the specific method of updating the adsorbent performance decay kinetic model is as follows: the collected performance characterization parameter after regeneration is added as a new data point to the historical performance parameter database.

[0067] The adsorbent performance decay kinetic model is a function that maps the number of regeneration cycles to adsorbent performance parameters.

[0068] The historical performance parameter database containing the new data points is fitted using a preset regression algorithm to generate the updated function as the updated adsorbent performance decay kinetic model.

[0069] In a preferred embodiment of the present invention, the specific manner of dynamically adjusting the adsorption breakthrough threshold is as follows: based on the updated adsorbent performance decay kinetic model, predicting the adsorbent performance decay rate of the next adsorption cycle.

[0070] A compensation coefficient is calculated based on the predicted performance degradation rate.

[0071] The adsorption penetration threshold of the current cycle is multiplied by the compensation coefficient to obtain an adjusted adsorption penetration threshold.

[0072] If the adjusted adsorption breakthrough threshold is lower than the preset minimum safety threshold, 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.

[0073] In a preferred embodiment of the present invention, the specific adjustment method of the process parameters of the graded desorption regeneration step is as follows: the performance characterization parameters after regeneration are compared with the performance characterization parameters after regeneration in the previous cycle, and the regeneration efficiency recovery degree is calculated.

[0074] Preferably, a method for calculating regeneration efficiency recovery is to use post-regeneration performance parameters as a benchmark, select characteristic parameters of dynamic adsorption capacity, such as the time it takes for the outlet concentration to reach breakthrough, and physical structural parameters, such as specific surface area and pore volume. The ratio of each parameter after regeneration in the current cycle to the corresponding parameter after regeneration in the previous cycle is calculated, and the average of these ratios is taken as the regeneration efficiency recovery degree. This value reflects the degree to which the regeneration process has restored adsorbent performance and is used to determine whether regeneration process parameters need to be adjusted.

[0075] If the regeneration efficiency recovery degree is lower than the preset regeneration efficiency target value, in the next regeneration cycle, the temperature of the regeneration medium in the desorption regeneration step is increased or its action time is extended.

[0076] One embodiment provides a method for setting a regeneration efficiency target value: using the initial adsorbent performance parameters as a benchmark, the dynamic adsorption capacity characteristic parameters and physical structure characteristic parameters of the new adsorbent are used as reference values. A certain ratio of the reference value is set as the initial regeneration efficiency target value, and the ratio is determined based on environmental standards and economic efficiency. Subsequently, as the adsorbent performance decays, an updated adsorbent performance decay kinetic model is combined to predict the theoretical upper limit of recovery in the next cycle. The corresponding ratio is used as the adjusted target value, ensuring that the target value is both feasible and ensures efficient system operation.

[0077] It's important to explain that increasing the temperature of the regeneration medium or extending its duration during the desorption regeneration step is intended to enhance adsorbent regeneration. Increasing the temperature enhances molecular thermal motion, making it easier for formaldehyde remaining in the adsorbent's pores to escape from adsorption sites. Extending the duration allows for full contact between the regeneration medium and the adsorbent, ensuring more formaldehyde is desorbed. By enhancing mass transfer and heat exchange, these two processes compensate for the decreased adsorbent activity caused by multiple regenerations, improve regeneration efficiency recovery, bring adsorbent performance closer to the target value, and ensure the stability of subsequent adsorption processes.

[0078] The adjustment amount of the process parameter is associated with the difference between the regeneration efficiency recovery degree and the regeneration efficiency target value through a preset mapping relationship.

[0079] Preferably, one method for setting the mapping relationship is to experimentally determine the optimal process parameter adjustment values, such as temperature increase or time extension, corresponding to the difference between different regeneration efficiency recovery levels and the target value, and establish a difference-adjustment value dataset. Using linear fitting or piecewise function methods, the difference is divided into several intervals, and a corresponding adjustment value is matched to each interval. The larger the difference, the larger the adjustment value, forming a preset mapping relationship. For example, a temperature increase of 5°C is achieved for a 10% difference, and a temperature increase of 12°C is achieved for a 20% difference. This is then written into the control system, and the corresponding adjustment value is called according to the real-time difference during regeneration to achieve precise parameter control.

[0080] Furthermore, the optimal process parameter adjustment refers to the optimal adjustment range for the regeneration medium temperature or reaction time to achieve the target regeneration efficiency recovery during graded desorption regeneration. For example, when the regeneration efficiency recovery is lower than the target, the regeneration effect corresponding to different temperature increases or time extensions can be experimentally tested to screen the adjustment value that achieves the desired recovery efficiency while minimizing energy consumption. This value is the optimal process parameter adjustment at this time, which can balance regeneration efficiency and economic efficiency.

[0081] The above contents are merely examples and explanations of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the present invention, they should all fall within the scope of protection of the present invention.

Claims

1. A circulating formaldehyde adsorption and regeneration system for plywood gluing, characterized in that: include: The anti-interference pre-treatment module uses an electrostatic-ultrasonic coupling demister to treat formaldehyde-containing air and remove paint mist particles; a humidity adaptive analysis module, which directs the formaldehyde-containing air that has undergone the anti-interference pretreatment through at least one adsorption tower based on the real-time monitored ambient humidity, and outputs purified air; A saturation monitoring module collects the formaldehyde concentration at the inlet and outlet of the adsorption tower, calculates the real-time adsorption saturation based on a pre-built adsorbent performance decay kinetic model, and compares it with a preset adsorption breakthrough threshold to generate a switching instruction; a graded desorption regeneration module, which cuts out the saturated adsorption tower from the self-purification adsorption pipeline according to the switching instruction 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 tail gas treatment module introduces the high-concentration formaldehyde mixed gas into a catalytic oxidation reactor to oxidize and decompose the formaldehyde therein; The performance attenuation evaluation and compensation module collects the performance characterization parameters of the saturated adsorption tower after regeneration, updates the adsorbent performance attenuation kinetic model, and dynamically adjusts the adsorption breakthrough threshold or the process parameters of the graded desorption regeneration step to compensate for the performance attenuation.

2. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 1, characterized in that: The specific analysis method of guiding and running through at least one adsorption tower is as follows: Setting a first adsorption path and a second adsorption path, wherein the first adsorption path runs through an adsorption region filled with a modified activated carbon adsorbent, and the second adsorption path runs through an adsorption region filled with a hydrophobic zeolite adsorbent; A humidity sensor is provided 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, the control pipeline valve is controlled 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 gluing according to claim 1, characterized in that: The specific method of calculating the real-time adsorption saturation is as follows: Using an inlet concentration sensor and an outlet concentration sensor, synchronously collecting the inlet formaldehyde concentration value and the outlet formaldehyde concentration value of the adsorption tower at a preset sampling frequency; Constructing a kinetic model for the attenuation of the adsorbent performance, wherein the model characterizes the attenuation relationship of the total adsorption capacity of the adsorbent as the number of regeneration cycles changes; According to the current number of regeneration cycles, the predicted total adsorption capacity of the current cycle is obtained from the adsorbent performance decay kinetic model; Performing time integration on the difference between the inlet formaldehyde concentration value and the outlet formaldehyde concentration value to obtain a cumulative amount of adsorbed formaldehyde; The cumulative adsorbed formaldehyde amount is compared with the predicted total adsorption capacity of the current cycle to obtain the real-time adsorption saturation.

4. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 1, characterized in that: The specific method of 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 instruction is output; otherwise, it is determined that no switching operation is required; The adsorption breakthrough threshold is a dynamic variable, the initial value of which is set according to the initial performance of the adsorbent and is adjusted after each performance decay evaluation and compensation step.

5. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 1, characterized in that: The specific analysis process of the graded desorption regeneration is as follows: In the first temperature rise and desorption stage, a regeneration medium at a first temperature is introduced into the adsorption tower. The first temperature is set to be above the desorption temperature point of water molecules and below the desorption temperature point of formaldehyde molecules, so as to preferentially decompose and remove water molecules adsorbed on the adsorbent. In the second temperature rise and decomposition stage, after completing the first temperature rise and decomposition stage, a regeneration medium at a second temperature is introduced into the adsorption tower. The second temperature is set to be above the decomposition temperature point of the formaldehyde molecules to decompose the formaldehyde molecules adsorbed by the adsorbent to form the high-concentration formaldehyde mixed gas.

6. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 1, characterized in that: The specific analysis method of the performance characterization parameters after regeneration is as follows: After the graded 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; Continuously monitor the formaldehyde concentration at the outlet of the adsorption tower, record the time from the start of the introduction of the test gas to the time when the formaldehyde concentration at the outlet reaches the preset breakthrough point concentration, and use this time as the dynamic adsorption capacity characteristic parameter of this regeneration; The specific surface area and pore volume of the adsorbent after graded desorption and regeneration in the adsorption tower were measured using nitrogen adsorption method 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 post-regeneration performance characterization parameter.

7. A circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 6, characterized in that: The specific method of updating the adsorbent performance decay kinetic model is as follows: Adding the collected post-regeneration performance characterization parameter as a new data point to a historical performance parameter database; The adsorbent performance decay kinetic model is a function that maps the number of regeneration cycles to adsorbent performance parameters; The historical performance parameter database containing the new data points is fitted using a preset regression algorithm to generate the updated function as the updated adsorbent performance decay kinetic model.

8. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 7, characterized in that: The specific method of dynamically adjusting the adsorption penetration threshold is as follows: Predicting the adsorbent performance decay rate of the next adsorption cycle based on the updated adsorbent performance decay kinetic model; calculating a compensation coefficient according to the predicted performance degradation rate; Multiplying the adsorption penetration threshold of the current cycle 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 of the next adsorption cycle is set to the minimum safety threshold; otherwise, it is set to the adjusted adsorption penetration threshold.

9. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 7, characterized in that: The specific adjustment method of the process parameters of the graded desorption regeneration step is as follows: Comparing the performance characterizing parameter after regeneration with the performance characterizing parameter after regeneration of the previous cycle to calculate the regeneration efficiency recovery degree; If the regeneration efficiency recovery degree is lower than the preset regeneration efficiency target value, then in the next regeneration cycle, the temperature of the regeneration medium in the desorption regeneration step is increased or its action time is extended; The adjustment amount of the process parameter is associated with the difference between the regeneration efficiency recovery degree and the regeneration efficiency target value through a preset mapping relationship.

10. The circulating formaldehyde adsorption and regeneration system for plywood gluing according to claim 1, characterized in that: The system also includes an intelligent control strategy based on multi-source data, which specifically includes: In addition to the formaldehyde concentration data, the bed temperature data and pressure drop data in the adsorption tower are also collected simultaneously; Establishing a correlation model, wherein the correlation model describes a nonlinear relationship between the outlet formaldehyde concentration, the bed temperature, the pressure drop, and the actual working state of the adsorbent; Inputting the real-time collected formaldehyde concentration data, the bed temperature data, and the pressure drop data into the correlation model, and outputting a correction value for the real-time adsorption saturation; The correction value is applied to the real-time adsorption saturation calculated by a pre-built adsorbent performance decay kinetic model to obtain a final saturation determination value, and the switching instruction is generated based on the final saturation determination value.

Images