An aircraft paint hangar mist treatment system and adsorption control method

Abstract

The application belongs to the technical field of environmental engineering, and discloses a paint mist treatment system for an aircraft paint spraying hangar and an adsorption and desorption control method. The system comprises a paint mist collecting device which forms a directional airflow in a paint spraying area and realizes quantitative calculation of the paint mist inlet concentration by combining the sampling unit with the flow and time parameters. The airflow uniform distribution device adopts a porous flow uniform plate and a guide grid structure to make the airflow velocity distribution entering the adsorption bed uniform. The adsorption and desorption device is partitioned and filled with activated carbon or molecular sieve, and the switching of adsorption and desorption is realized by concentration determination and adsorption capacity calculation. The energy recovery and control device recovers the sensible heat of the desorption tail gas by using a plate-fin heat exchanger, and part of the airflow is backflowed to the adsorption inlet for preheating. The method comprises the steps of inlet concentration determination, adsorption capacity comparison, desorption energy consumption calculation and heat recovery efficiency evaluation, so as to realize efficient removal of paint mist particles and organic solvent components in the waste gas of the paint spraying hangar.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering technology, specifically a paint mist treatment system for aircraft paint spraying hangars and a method for adsorption-desorption control. Background Technology

[0002] During the operation of aircraft painting hangars, painting operations generate a large amount of waste gas containing organic solvents and paint mist particles. These pollutants are characterized by high concentration, complex composition, and uneven emissions. Existing hangar paint mist treatment methods mainly rely on a combination of empirical parameters and unit operation, but there are still shortcomings in several aspects. First, in the detection stage, paint mist concentration is often determined by estimating the air supply volume or by single-point light scattering, lacking quantitative calculations based on sampling quality and volumetric flow rate, resulting in significant errors in inlet concentration determination. Second, in the adsorption stage, integrated bed-type activated carbon devices are commonly used, and switching criteria often rely on operating time or bed pressure drop, which cannot reflect the actual load state of the adsorbent. This often leads to premature switching causing increased energy consumption, or delayed switching causing emissions to exceed standards.

[0003] Secondly, in the desorption stage, existing processes typically employ constant power heating and fixed vacuum pumping, failing to combine airflow parameters and adsorbent desorption enthalpy for energy consumption calculations. This results in a mismatch between heating input and desorption demand, leading to low energy efficiency. Finally, in the exhaust gas treatment stage, the high-temperature waste gas generated during desorption is mostly directly discharged or undergoes only simple heat exchange. No scheduling mechanism based on heat exchange efficiency and purification efficiency has been established, which not only fails to achieve full recovery and utilization of waste heat but also easily causes the risk of secondary emissions.

[0004] It is evident that existing paint mist treatment technologies for spray booths have deficiencies in detection, adsorption, desorption, and energy recovery. Their common problem lies in the lack of data transfer and energy closure between multiple stages, and the absence of a collaborative control path centered on formulaic judgment. Summary of the Invention

[0005] The purpose of this invention is to provide a paint mist treatment system and adsorption-desorption control method for aircraft paint hangars, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a paint mist treatment system for aircraft paint spraying hangars, the system comprising: The paint mist collection device, located around the spraying area, has a multi-stage filtration layer and a flow guide structure, used to form a directional airflow and capture paint mist particles during the spraying process. An airflow equalization device, including a porous flow equalization plate and a guide grid, is arranged between the paint mist collection device and the adsorption device to equalize the flow velocity and reduce local eddies before the paint mist enters the adsorption device. The adsorption and desorption device is filled with granular activated carbon or honeycomb molecular sieve, and is equipped with an electrically heated desorption component on the outside. It is connected to the airflow uniform distribution device through a circulating fan. The energy recovery and control device, including a plate-fin heat exchanger and a temperature and humidity sensor, is used to recover the sensible heat of the high-temperature gas flow discharged during the desorption process, and adjust the heating power and fan speed based on real-time monitoring signals to form a closed energy cycle.

[0007] Preferably, the paint mist collecting device is used for: (1) Install a flow guide around the spray painting area. The flow guide is tightly sealed to the spray painting station through a fixed bracket. Its outlet position is strictly coaxial with the multi-stage filter layer to ensure that the paint mist airflow passes through each stage of the filter layer in a straight line. The multi-stage filter layer includes a metal wire mesh layer and a fiber condensation layer from upstream to downstream. The typical pore size range of the metal wire mesh layer is 0.3 to 0.5 mm, which is used to block large particles of paint mist. The fiber coagulation layer is 10-15 mm thick and is used to coagulate small particles into large droplets for easy subsequent collection. A sampling port with a diameter of 10 mm is set at the front end of the flow guide hood outlet, and a volumetric flow meter with a range of 0-500 L / min is fixedly installed therein. During the sampling process, the sampling volume and duration are denoted as Q and t, respectively. The mass of the paint mist obtained by weighing the filter membrane is mp. The inlet concentration is obtained using the paint mist inlet concentration calculation formula. This concentration data is received by the control unit and used as an input parameter in the adsorption capacity calculation formula, where To ensure the quality of the adsorption bed filling, thus establishing a clear data interface between the detection and adsorption processes; Formula for calculating paint mist inlet concentration: ; In the formula: The inlet paint mist concentration of the spray airflow represents the level of pollutants before entering the adsorption device. It is the core output parameter of the detection and flow equalization unit and serves as the input signal for subsequent adsorption control. The quality of paint mist obtained by filtering and sampling is detected at the outlet of the guide hood, which is part of the detection process of the paint mist collection device. The volumetric flow rate was measured by a flow meter installed at the sampling port of the flow guide shroud; The sampling duration is a standard period set by the control unit; (2) Set a set of differential pressure taps at the front and rear ends of the multi-stage filter layer. The distance between the taps and the filter layer surface is 50 mm. They are connected to differential pressure transmitters to collect the pressure difference before and after the filter layer in real time. After the differential pressure signal is converted into an electrical signal by the transmitter, it is stored synchronously with the parameters of volumetric flow rate Q and sampling time t to ensure the consistency between the inlet concentration calculation formula and the operating condition parameters. A transition cavity is set between the outlet of the flow guide and the downstream flow equalization plate. The transition cavity is a closed cuboid structure with a length designed to be 4 to 6 times the thickness of the flow equalization plate. If it is less than 4 times, it will cause uneven airflow velocity distribution, and if it is greater than 6 times, it will cause the device to be too large. Therefore, this range is the optimal structural condition. The transition cavity serves as the input boundary of the flow equalization device, ensuring that the concentration calculated using the paint mist inlet concentration formula is within acceptable limits. The adsorption capacity q calculated by the adsorption capacity calculation formula remains stable and consistent before being transferred to the adsorption bed.

[0008] Preferably, the airflow distribution device is used for: (1) In the airflow uniform distribution device, the opening ratio of the porous flow equalization plate is set to 30-50%, the single hole diameter is 1.5-3.0 mm, the plate body is made of stainless steel and is sealed and fixed to the pipe wall by the frame. A guide grid is arranged in front of the flow equalization plate, and the grid plate is perpendicular to the plate surface at 90° to improve the uniformity of the flow field. A dot matrix flow velocity sensor is installed downstream of the flow equalization plate, with the measuring points covering more than 80% of the effective cross-sectional area, to obtain the average velocity of the cross-section in real time. At the same time, a sampling port is set downstream of the flow equalization plate, and the mass of paint mist particles is obtained by weighing through a filter membrane. The above-mentioned flow equalization plate, guide grid and sampling arrangement constitute the structural basis for inlet concentration determination, providing accurate boundary conditions for subsequent calculation formulas. (2) The velocity field obtained by the dot matrix flow velocity sensor is used to calculate the volumetric flow rate Q, combined with the sampling time t and particle mass. Substitute into the formula The inlet concentration of paint mist was obtained. ; A straight pipe section, 6 to 10 times the hydraulic diameter, is installed between the downstream of the flow equalization plate and the inlet of the adsorption device to ensure that the velocity field is fully developed and stabilized before entering the adsorption bed. The sensor and valve assembly work together to... With adsorption material parameters Substitute K into the adsorption capacity formula to calculate the real-time adsorption load; When q reaches the set threshold, the control signal triggers the switching valve group of the adsorption and desorption device, automatically completing the switching between adsorption and desorption conditions, realizing a closed-loop process from flow field regulation → concentration determination → adsorption calculation → valve group control. The adsorption capacity formula is: ; In the formula: The actual unit adsorption capacity is determined by the airflow volumetric flow rate Q output by the array-type flow velocity sensor installed in the straight pipe section downstream of the flow equalization plate and the particle mass m measured at the sampling port. p The q is calculated together with the sampling time t, and then substituted into the adsorption capacity determination formula for calculation. When the q approaches the preset threshold q... th At that time, the calculation results directly drive the switching valve group to switch between adsorption and desorption conditions; The maximum adsorption capacity, determined by experimental calibration during system design, is an important basis for selecting adsorbents. The adsorption constant, representing the affinity of the adsorbent for the components of paint mist, is a material parameter that is calibrated experimentally and fixed in the control algorithm. The inlet concentration is derived from the formula for calculating the inlet concentration of paint mist.

[0009] Preferably, the adsorption and desorption device is used for: (1) The adsorption bed adopts a granular activated carbon or honeycomb molecular sieve partitioning method. The bed body is divided into multiple independent partitions. Each partition is equipped with inlet and outlet valves, bypass valves and sampling ports to control the airflow path and collect concentration parameters. The adsorbent loading amount, number of partitions and switching threshold of each partition are all based on the adsorption capacity calculation formula: ; To determine, in the formula, The inlet concentration (mg / m3) measured at the sampling port; The concentration at the zone outlet (mg / m^3); The volumetric flow rate is (m³ / min). The sampling time is long (min); This refers to the adsorbent mass (kg) of this zone; simultaneously, by measuring the maximum adsorption capacity... With adsorption rate constant The experimental calibration can form corresponding partition switching thresholds to ensure that different partitions are switched sequentially under a predetermined capacity; temperature monitoring points are set on the bed shell to monitor the partition temperature in real time and avoid parameter deviations caused by adsorption exotherm. By combining the above-mentioned zoned valve control with formulaic judgment, a quantifiable basis is achieved for switching adsorption beds during operation, thus providing a refined control structure that differs from existing integrated filling schemes.

[0010] (2) After the adsorption bed is nearly saturated, the desorption pathway is activated. The desorbed gas is heated by an electric heater to generate an airflow at a temperature of 120°C to 150°C, which then enters the adsorption bed. At the same time, the bed pressure is maintained between 10 kPa and 30 kPa. During desorption, the system calculates the energy demand according to the following energy consumption formula: ; Energy consumption for this desorption (kJ); The desorbed gas mass flow rate (kg / s) was collected by a flow meter at the adsorption inlet. The specific heat capacity of the gas is provided by a physical property database, and the value is determined based on the composition of the desorbed gas. ; The desorption temperature is set (K) by the heating element controller of the desorption device; The ambient temperature before adsorption was monitored by a temperature sensor (K); The latent heat of desorption of the target organic component can be found in the chemical property table (kJ / kg); The mass of organic matter desorbed in this desorption was calculated based on mass balance (kg); The desorption energy consumption calculated by this formula It forms a closed-loop linkage with the system's energy recovery device. When the valve group calculates that q is close to the saturation threshold, it automatically switches the gas path to guide the airflow into the energy recovery device, ensuring that the heat after desorption is recovered and continuously driving the system to circulate.

[0011] Preferably, the energy recovery and control device is used for: (1) A plate-fin heat exchanger is arranged in the desorption branch, and temperature sensors are installed at the inlet and outlet of the hot side and the cold side, respectively. The data is collected in real time by the PLC, and the desorption gas mass flow rate is also collected synchronously. This parameter is measured by a flow meter (kg / s), and the heat exchange area of ​​the heat exchanger. The flow rate ratio is determined by the following heat recovery efficiency formula: ; in: Heat recovery efficiency (dimensionless); The isobaric specific heat capacity of the desorbed gas (kJ / (kg·K)) is determined by the physical property database; Hot-side inlet and outlet temperatures (K); Cold side inlet and outlet temperatures (K); Desorbed gas mass flow rate (kg / s); A return branch pipe is arranged at the cold side outlet. The return branch pipe forms a closed loop with the adsorption bed inlet, so that the preheated gas flow can be directly used as the carrier gas in the next adsorption cycle, thereby improving the thermal utilization rate of the system. (2) The return branch pipe is connected to the adsorption inlet valve group to form a closed loop of plate-fin heat exchanger-return branch pipe-adsorption inlet. The PLC calls the heat recovery efficiency formula at the same time during operation. Formula for system purification and removal rate: ; In the formula: Overall purification efficiency is the ultimate performance evaluation indicator for hangar paint mist treatment systems; The concentration of pollutants (mg / m3) in the airflow entering the adsorption bed is measured by the sampling port and concentration sensor; The pollutant concentration (mg / m3) in the outlet gas flow of the adsorption bed was measured at the tail gas sampling point; PLC based and The real-time monitoring values ​​are used to dynamically schedule the power of the desorption heater, the speed of the desorption fan, and the opening and closing sequence of the switching valve group, thereby maintaining the data and energy balance and linkage between the four parts of the adsorption unit, desorption unit, heat exchanger and return pipeline. The above linkage logic ensures that a closed-loop control relationship is established between desorption energy consumption, heat recovery and purification efficiency, rather than a single empirical adjustment.

[0012] The present invention also provides a method for controlling the adsorption and desorption of paint mist in aircraft paint hangars, based on the above system, and the specific steps are as follows: During the painting process, S1 activates the paint mist collection device to form a directional airflow and capture paint mist particles. The airflow is then balanced by the flow equalization mechanism before entering the adsorption bed, where the organic components are adsorbed in granular activated carbon or molecular sieve adsorption materials until the adsorption capacity reaches the set threshold. When the adsorption bed is close to saturation, S2 switches to desorption mode, using a high-temperature airflow of 120℃ to 150℃ under reduced pressure to desorb the adsorption material and exhaust the desorption waste gas. The waste gas undergoes sensible heat recovery via a plate heat exchanger for preheating the airflow in the next cycle. During the desorption process, the monitoring and control unit dynamically adjusts the heating power and fan speed based on real-time feedback of temperature, humidity, and concentration to stabilize the desorption pressure within the range of 10kPa to 30kPa, ensuring the continuous stability of the adsorption and desorption cycle.

[0013] Preferably, the specific steps of S1 are as follows: During the painting operation, the paint mist collection device is activated, forming a directional airflow around the painting area. As the airflow passes through the filtration and sampling unit, paint mist particles are captured by the filter membrane. During sampling, the volumetric flow meter collects the volumetric flow rate of the airflow. The timer records the sampling duration. The mass of paint mist captured on the filter membrane is obtained by weighing device. Based on the above parameters, the inlet concentration is calculated: ; in, The inlet paint mist concentration (mg / m3) is used as a numerical input and transmitted to the flow equalization and regulation mechanism to provide boundary conditions for the subsequent adsorption process. S12 inlet concentration The input flow equalization mechanism rectifies the airflow through a porous flow equalization plate and a guide grid before it enters the adsorption bed. The adsorption bed is filled with granular activated carbon or honeycomb molecular sieve material to capture the organic components in the airflow. The adsorption process is determined using an adsorption capacity formula. ; in, Equilibrium adsorption capacity per unit adsorbent (mg / g); The maximum adsorption capacity (mg / g) of the adsorbent is determined by a breakthrough curve experiment. The adsorption constant (m³ / mg) was obtained by fitting the adsorption data from an isothermal adsorption experiment. The inlet concentration calculated in step S11 is obtained by the system. With set threshold When a comparison is performed, When the switching valve group enters the desorption preparation state, the above process realizes the continuous operation steps from inlet concentration calculation to adsorption capacity determination, and provides a quantitative basis for the switching between adsorption and desorption.

[0014] Preferably, the specific steps of S2 are as follows: S21 When the adsorption capacity of the adsorption bed With threshold When the comparison reaches the saturation value, the switching valve group closes the adsorption path and opens the desorption path, so that the system enters the desorption mode; The heating unit provides a high-temperature gas flow of 120°C to 150°C in the desorption path, and maintains the bed pressure at 10 kPa to 30 kPa under the action of a vacuum pump. This high-temperature gas flow enters the adsorption bed under reduced pressure to desorb the packed granular activated carbon or molecular sieve material. The desorption process uses the desorption energy consumption calculation formula: ; In the formula, To desorb the total energy consumption ; The mass flow rate of the desorbed gas (kg / s) is measured by a flow meter. The specific heat capacity of the gas (kJ / (kg·K)) was obtained from a physical property database. Temperature of the desorbed gas (K); The initial ambient temperature (K); The latent heat of desorption of the target solvent (kJ / kg); The real-time calculation result of this formula is used as the energy consumption judgment value to determine the mass (kg) of solvent released by desorption, ensuring that the desorption process is carried out under quantitative energy monitoring. Unlike the existing technology that relies solely on time control for desorption, a closed logic chain of adsorption amount judgment, valve group switching, and energy consumption calculation has been established. The high-temperature exhaust gas generated during the S22 desorption process is discharged through a pipeline and then enters a plate-fin heat exchanger. Temperature sensors are installed at the inlet and outlet of the heat exchanger on both the hot and cold sides to measure the temperature in real time. Simultaneously, combined with the desorbed gas mass flow rate Call the heat recovery efficiency formula: ; In the formula: Heat recovery efficiency (%); The mass flow rate is the gas flow rate (kg / s). Specific heat capacity (kJ / (kg·K)); The inlet and outlet temperatures on the hot side (K); The inlet and outlet temperatures (K) are for the cold side. The cold-side outlet of the heat exchanger is equipped with a return branch pipe, which leads part of the preheated airflow back to the adsorption bed inlet as the preheated airflow for the next cycle. Calculated by formula Compared with the energy consumption value in step S21 A corresponding relationship is established to comprehensively evaluate the energy efficiency level of the desorption process and serve as one of the bases for cycle switching. In this way, a continuous step logic of energy consumption calculation, heat recovery efficiency and reflux preheating is established, which is different from the unidirectional emission of existing technologies and realizes the synergistic improvement of energy balance and purification efficiency.

[0015] The beneficial effects of this invention are as follows: 1. This invention obtains concentration data consistent with actual operating conditions by setting up a sampling port and flow detection in the paint mist collection device, and directly transmits this data to the flow equalization and adsorption device for linkage judgment. Unlike the traditional method of estimating concentration based on empirical parameters, this invention establishes a measurable and transmissible data chain, which provides a clear basis for adsorption switching conditions and avoids premature switching or emission exceedance caused by judgment distortion. Thus, a dynamic connection is formed between the detection and adsorption links, improving the controllability and consistency of waste gas treatment.

[0016] 2. This invention, through the combined adjustment of gas heating and depressurization conditions, enables the desorption process to match the actual load of the adsorbent, rather than using constant heating and fixed pumping. This setting effectively reduces excess energy input and avoids secondary pollution caused by insufficient desorption. At the same time, the desorption path is connected to the valve group switching, enabling automatic transition between adsorption and desorption, improving the continuity and stability of system operation. Compared with existing schemes that rely on fixed cycle operation, this invention achieves higher energy efficiency and environmental compliance in the desorption process.

[0017] 3. This invention introduces a heat exchange and reflux structure into the desorption branch, enabling the high-temperature exhaust gas generated during desorption to recover heat before release, and introducing part of the preheated airflow into the adsorption inlet of the next cycle. This design not only reduces energy waste, but also forms a closed loop in terms of energy and airflow between the desorption and adsorption stages. At the same time, heat exchange efficiency and purification effect are incorporated into the same scheduling framework, enabling the system to achieve a balance between pollutant removal rate and energy utilization rate. Compared with the unidirectional emission or simple heat exchange mode of the prior art, this invention establishes a cross-stage linkage mechanism, thereby improving the overall operational economy and environmental friendliness. Attached Figure Description

[0018] Figure 1 This is a flowchart of the aircraft paint mist treatment system for hangars in this invention. Figure 2 This is a flowchart of the adsorption-desorption control method for treating paint mist in aircraft paint hangars according to the present invention. Detailed Implementation

[0019] 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.

[0020] like Figures 1 to 2As shown, this embodiment of the invention provides a paint mist treatment system for aircraft paint spraying hangars, the system comprising: The paint mist collection device, located around the spraying area, has a multi-stage filtration layer and a flow guide structure, used to form a directional airflow and capture paint mist particles during the spraying process. An airflow equalization device, including a porous flow equalization plate and a guide grid, is arranged between the paint mist collection device and the adsorption device to equalize the flow velocity and reduce local eddies before the paint mist enters the adsorption device. The adsorption and desorption device is filled with granular activated carbon or honeycomb molecular sieve, and is equipped with an electrically heated desorption component on the outside. It is connected to the airflow uniform distribution device through a circulating fan. The energy recovery and control device, including a plate-fin heat exchanger and a temperature and humidity sensor, is used to recover the sensible heat of the high-temperature gas flow discharged during the desorption process, and adjust the heating power and fan speed based on real-time monitoring signals to form a closed energy cycle. Example

[0021] Taking a certain type of aircraft painting hangar as an example, the painting area is 600m², and the designed air volume is 45000m³ / h.

[0022] During the painting process, the paint mist collection device is arranged along the outer edge of the painting area. The outlet of the flow guide is coaxially connected to the multi-stage filter layer, which includes a metal wire mesh layer and a fiber coagulation layer to intercept large particles of paint mist. The front end of the collection device is equipped with a sampling port, a volumetric flow meter and a timer to collect the airflow volumetric flow rate Q and the sampling time t, and weigh the filter membrane to obtain the paint mist mass mp. The inlet concentration Cin is obtained by converting it through the inlet concentration calculation formula, and the data interface transmits this parameter to the downstream flow equalization device.

[0023] When the airflow passes through the flow equalization device, it passes through a porous flow equalization plate with an opening ratio of 40% and a pore size of 2mm. A guide grid is installed in front of the plate, arranged at 90° to the plate surface, to rectify the flow and eliminate eddies. A dot matrix flow velocity sensor is installed downstream of the flow equalization plate to monitor the flow velocity distribution in real time. The rectified airflow enters the adsorption device. The adsorption bed is divided into sections filled with honeycomb molecular sieves, with each section containing 150kg of sieves. It is equipped with inlet and outlet valves and a bypass valve. Adsorption is determined based on the adsorption formula, and the adsorption capacity q is calculated in real time and compared with a set threshold q. th According to the comparison, when q approaches the threshold, the switching valve group closes the adsorption path and opens the desorption path.

[0024] In desorption mode, the electric heater outputs a high-temperature gas flow of 130℃, and the vacuum pump maintains the bed pressure at 20kPa. The high-temperature gas flow enters the adsorption bed to complete desorption. The desorption energy consumption is calculated in real time according to the desorption energy consumption formula. The desorption tail gas is introduced into a plate-fin heat exchanger through a branch. Temperature sensors are installed at the inlet and outlet of the hot and cold sides, respectively. The PLC collects temperature and flow data and uses the heat exchange efficiency formula to calculate η.h Part of the cold-side outlet airflow returns to the adsorption inlet through the return branch pipe as preheated carrier gas, thus forming a closed loop of adsorption, desorption and energy recovery.

[0025] Through the above implementation methods, the system achieves quantitative detection of inlet concentration, real-time determination of adsorption threshold, quantitative calculation of desorption energy consumption, and effective recovery of exhaust gas heat, ensuring that the paint spraying hangar has dual protection of pollutant removal and energy consumption control under continuous operation of high air volume.

[0026] The paint mist collection device is used for: A flow guide is installed around the perimeter of the spray painting area. The flow guide is tightly sealed to the spray painting station through a fixed bracket. Its outlet position is strictly coaxial with the multi-stage filter layer to ensure that the paint mist airflow passes through each stage of the filter layer in a straight line. The multi-stage filter layer includes a metal mesh layer and a fiber condensation layer from upstream to downstream. The typical pore size range of the metal mesh layer is 0.3 to 0.5 mm, which is used to block large particles of paint mist. The fiber coagulation layer is 10-15 mm thick and is used to coagulate small particles into large droplets for easy subsequent collection. A sampling port with a diameter of 10 mm is set at the front end of the flow guide hood outlet, and a volumetric flow meter with a range of 0-500 L / min is fixedly installed therein. During the sampling process, the sampling volume and duration are denoted as Q and t, respectively. The mass of the paint mist obtained by weighing the filter membrane is mp. The inlet concentration is obtained using the paint mist inlet concentration calculation formula. This concentration data is received by the control unit and used as an input parameter in the adsorption capacity calculation formula, where To ensure the quality of the adsorption bed filling, thus establishing a clear data interface between the detection and adsorption processes; Formula for calculating paint mist inlet concentration: ; In the formula: The inlet paint mist concentration of the spray airflow represents the level of pollutants before entering the adsorption device. It is the core output parameter of the detection and flow equalization unit and serves as the input signal for subsequent adsorption control. The quality of paint mist obtained by filtering and sampling is detected at the outlet of the guide hood, which is part of the detection process of the paint mist collection device. The volumetric flow rate was measured by a flow meter installed at the sampling port of the flow guide shroud; The sampling duration is a standard period set by the control unit; A set of differential pressure taps is set at the front and rear of the multi-stage filter layer. The taps are 50mm away from the filter layer surface and are connected to a differential pressure transmitter to collect the pressure difference across the filter layer in real time. After the differential pressure signal is converted into an electrical signal by the transmitter, it is stored synchronously with the parameters of volumetric flow rate Q and sampling time t to ensure the consistency between the inlet concentration calculation formula and the operating condition parameters. A transition cavity is set between the outlet of the flow guide and the downstream flow equalization plate. The transition cavity is a closed cuboid structure with a length designed to be 4 to 6 times the thickness of the flow equalization plate. If it is less than 4 times, it will cause uneven airflow velocity distribution, and if it is greater than 6 times, it will cause the device to be too large. Therefore, this range is the optimal structural condition. The transition cavity serves as the input boundary of the flow equalization device, ensuring that the concentration calculated using the paint mist inlet concentration formula is within acceptable limits. The adsorption capacity q calculated by the adsorption capacity calculation formula remains stable and consistent before being transferred to the adsorption bed.

[0027] The airflow distribution device is used for: In the airflow equalization device, the opening ratio of the porous flow equalization plate is set to 30-50%, the single hole diameter is 1.5-3.0 mm, the plate body is made of stainless steel and is pressed and sealed to the pipe wall by a frame, and a guide grid is arranged in front of the flow equalization plate, with the grid plates perpendicular to the plate surface. Cross-flow to improve flow field uniformity; A dot matrix flow velocity sensor is installed downstream of the flow equalization plate, with the measuring points covering more than 80% of the effective cross-sectional area, to obtain the average velocity of the cross-section in real time. At the same time, a sampling port is set downstream of the flow equalization plate, and the mass of paint mist particles is obtained by weighing through a filter membrane. The above-mentioned flow equalization plate, guide grid and sampling arrangement constitute the structural basis for inlet concentration determination, providing accurate boundary conditions for subsequent calculation formulas. The velocity field obtained by the dot-matrix flow velocity sensor is used to calculate the volumetric flow rate Q, combined with the sampling time t and particle mass. Substitute into the formula The inlet concentration of paint mist was obtained. ; A straight pipe section, 6 to 10 times the hydraulic diameter, is installed between the downstream of the flow equalization plate and the inlet of the adsorption device to ensure that the velocity field is fully developed and stabilized before entering the adsorption bed. The sensor and valve assembly work together to... With adsorption material parameters Substitute these values ​​into the adsorption capacity formula to calculate the real-time adsorption load; When q reaches the set threshold, the control signal triggers the switching valve group of the adsorption and desorption device, automatically completing the switching between adsorption and desorption conditions, realizing a closed-loop process from flow field regulation → concentration determination → adsorption calculation → valve group control. The adsorption capacity formula is: ; In the formula: The actual unit adsorption capacity is determined by the airflow volumetric flow rate Q output by the array-type flow velocity sensor installed in the straight pipe section downstream of the flow equalization plate and the particle mass measured at the sampling port. The value is calculated by combining the sampling time t and the adsorption capacity determination formula. When q approaches the preset threshold q, the adsorption capacity is determined. th At that time, the calculation results directly drive the switching valve group to switch between adsorption and desorption conditions; The maximum adsorption capacity, determined by experimental calibration during system design, is an important basis for selecting adsorbents. The adsorption constant, representing the affinity of the adsorbent for the components of paint mist, is a material parameter that is calibrated experimentally and fixed in the control algorithm. The inlet concentration is derived from the formula for calculating the inlet concentration of paint mist.

[0028] The adsorption and desorption devices are used for: The adsorption bed uses granular activated carbon or honeycomb molecular sieves in a partitioned filling method. The bed is divided into multiple independent partitions, each equipped with inlet / outlet valves, bypass valves, and sampling ports to control the airflow path and collect concentration parameters. The adsorbent loading amount, number of partitions, and switching threshold of each partition are all based on the adsorption capacity calculation formula: ; To determine, in the formula, The inlet concentration (mg / m3) measured at the sampling port; The concentration at the zone outlet (mg / m^3); The volumetric flow rate is (m³ / min). The sampling time is long (min); This refers to the adsorbent mass (kg) of this zone; simultaneously, by measuring the maximum adsorption capacity... With adsorption rate constant The experimental calibration can form corresponding partition switching thresholds to ensure that different partitions are switched sequentially under a predetermined capacity; temperature monitoring points are set on the bed shell to monitor the partition temperature in real time and avoid parameter deviations caused by adsorption exotherm. By combining the above-mentioned zoned valve control with formulaic judgment, a quantifiable basis is achieved for switching adsorption beds during operation, thus providing a refined control structure that differs from existing integrated filling schemes.

[0029] After the adsorption bed approaches saturation, the desorption pathway is activated. The desorbed gas is heated to 120°C to 150°C by an electric heater and then enters the adsorption bed. Simultaneously, the bed pressure is maintained between 10 kPa and 30 kPa. During desorption, the system calculates the energy requirement based on the following energy consumption formula: ; Energy consumption for this desorption (kJ); The desorbed gas mass flow rate (kg / s) was collected by a flow meter at the adsorption inlet. The specific heat capacity of the gas is provided by a physical property database, and the value is determined based on the composition of the desorbed gas. ; The desorption temperature is set (K) by the heating element controller of the desorption device; The ambient temperature before adsorption was monitored by a temperature sensor (K); The latent heat of desorption of the target organic component can be found in the chemical property table (kJ / kg); The mass of organic matter desorbed in this desorption was calculated based on mass balance (kg); The desorption energy consumption calculated by this formula It forms a closed-loop linkage with the system's energy recovery device. When the valve group calculates that q is close to the saturation threshold, it automatically switches the gas path to guide the airflow into the energy recovery device, ensuring that the heat after desorption is recovered and continuously driving the system to circulate.

[0030] The energy recovery and control device is used for: A plate-fin heat exchanger is arranged in the desorption branch, with temperature sensors installed at the inlet and outlet of the hot and cold sides, respectively. The data is collected in real time by the PLC, and the desorption gas mass flow rate is also collected synchronously. This parameter is measured by a flow meter (kg / s), and the heat exchange area of ​​the heat exchanger. The flow rate ratio is determined by the following heat recovery efficiency formula: ; in: Heat recovery efficiency (dimensionless); The isobaric specific heat capacity of the desorbed gas (kJ / (kg·K)) is determined by the physical property database; Hot-side inlet and outlet temperatures (K); Cold side inlet and outlet temperatures (K); Desorbed gas mass flow rate (kg / s); A return branch pipe is arranged at the cold side outlet. The return branch pipe forms a closed loop with the adsorption bed inlet, so that the preheated gas flow can be directly used as the carrier gas in the next adsorption cycle, thereby improving the thermal utilization rate of the system. The return branch pipe is connected to the adsorption inlet valve group, forming a closed loop of plate-fin heat exchanger-return branch pipe-adsorption inlet. During operation, the PLC simultaneously calls the heat recovery efficiency formula. Formula for system purification and removal rate: ; In the formula: Overall purification efficiency is the ultimate performance evaluation indicator for hangar paint mist treatment systems; The concentration of pollutants (mg / m3) in the airflow entering the adsorption bed is measured by the sampling port and concentration sensor; The pollutant concentration (mg / m3) in the outlet gas flow of the adsorption bed was measured at the tail gas sampling point; PLC based and The real-time monitoring values ​​are used to dynamically schedule the power of the desorption heater, the speed of the desorption fan, and the opening and closing sequence of the switching valve group, thereby maintaining the data and energy balance and linkage between the four parts of the adsorption unit, desorption unit, heat exchanger and return pipeline. The above linkage logic ensures that a closed-loop control relationship is established between desorption energy consumption, heat recovery and purification efficiency, rather than a single empirical adjustment.

[0031] The present invention also provides a method for controlling the adsorption and desorption of paint mist in aircraft paint hangars, based on the above system, and the specific steps are as follows: During the painting process, the paint mist collection device is activated to form a directional airflow and capture paint mist particles. The airflow is then balanced by the flow equalization mechanism before entering the adsorption bed, where the organic components are adsorbed in granular activated carbon or molecular sieve adsorption materials until the adsorption capacity reaches the set threshold. When the adsorption bed is close to saturation, the system switches to desorption mode, using a high-temperature airflow of 120°C to 150°C to desorb the adsorption material under reduced pressure, and then exhausts the desorption waste gas. The waste gas undergoes sensible heat recovery via a plate heat exchanger to preheat the airflow for the next cycle. During the desorption process, the monitoring and control unit dynamically adjusts the heating power and fan speed based on real-time feedback of temperature, humidity, and concentration to stabilize the desorption pressure within the range of 10 kPa to 30 kPa, ensuring the continuous stability of the adsorption and desorption cycles.

[0032] The specific steps of S1 are as follows: During the painting operation, the paint mist collection device is activated, forming a directional airflow around the painting area. As the airflow passes through the filtration and sampling unit, paint mist particles are captured by the filter membrane. During sampling, the volumetric flow meter collects the airflow volumetric flow rate. The timer records the sampling duration. The mass of paint mist captured on the filter membrane is obtained by weighing device. Based on the above parameters, the inlet concentration is calculated: ; in, The inlet paint mist concentration (mg / m3) is used as a numerical input and transmitted to the flow equalization and regulation mechanism to provide boundary conditions for the subsequent adsorption process. Inlet concentration The input flow equalization mechanism rectifies the airflow through a porous flow equalization plate and a guide grid before it enters the adsorption bed. The adsorption bed is filled with granular activated carbon or honeycomb molecular sieve material to capture the organic components in the airflow. The adsorption process is determined using an adsorption capacity formula. ; in, Equilibrium adsorption capacity per unit adsorbent (mg / g); The maximum adsorption capacity (mg / g) of the adsorbent is determined by a breakthrough curve experiment. The adsorption constant (m³ / mg) was obtained by fitting the adsorption data from an isothermal adsorption experiment. The inlet concentration calculated in the previous step is obtained by the system. With set threshold When a comparison is performed, When the switching valve group enters the desorption preparation state, the above process realizes the continuous operation steps from inlet concentration calculation to adsorption capacity determination, and provides a quantitative basis for the switching between adsorption and desorption.

[0033] The specific steps of S2 are as follows: When the adsorption capacity of the adsorption bed With threshold When the comparison reaches the saturation value, the switching valve group closes the adsorption path and opens the desorption path, so that the system enters the desorption mode; The heating unit provides a high-temperature gas flow of 120°C to 150°C in the desorption path, and maintains the bed pressure at 10 kPa to 30 kPa under the action of a vacuum pump. This high-temperature gas flow enters the adsorption bed under reduced pressure to desorb the packed granular activated carbon or molecular sieve material. The desorption process uses the desorption energy consumption calculation formula: ; In the formula, Total energy consumed for desorption (kJ); The mass flow rate of the desorbed gas (kg / s) is measured by a flow meter. The specific heat capacity of the gas (kJ / (kg·K)) was obtained from a physical property database. Temperature of the desorbed gas (K); The initial ambient temperature (K); The latent heat of desorption of the target solvent (kJ / kg); The real-time calculation result of this formula is used as the energy consumption judgment value to determine the mass (kg) of solvent released by desorption, ensuring that the desorption process is carried out under quantitative energy monitoring. Unlike the existing technology that relies solely on time control for desorption, a closed logic chain of adsorption amount judgment, valve group switching, and energy consumption calculation has been established. The high-temperature exhaust gas generated during desorption is discharged through pipelines and then enters a plate-fin heat exchanger. Temperature sensors are installed at the inlet and outlet of the heat exchanger on both the hot and cold sides to measure the temperature in real time. Simultaneously, combined with the desorbed gas mass flow rate Call the heat recovery efficiency formula: ; In the formula: Heat recovery efficiency (%); The mass flow rate is the gas flow rate (kg / s). Specific heat capacity (kJ / (kg·K)); The inlet and outlet temperatures on the hot side (K); The inlet and outlet temperatures (K) are for the cold side. The cold-side outlet of the heat exchanger is equipped with a return branch pipe, which leads part of the preheated airflow back to the adsorption bed inlet as the preheated airflow for the next cycle. Calculated by formula Compared with the energy consumption value in the previous step A corresponding relationship is established to comprehensively evaluate the energy efficiency level of the desorption process and serve as one of the bases for cycle switching. In this way, a continuous step logic of energy consumption calculation, heat recovery efficiency and reflux preheating is established, which is different from the unidirectional emission of existing technologies and realizes the synergistic improvement of energy balance and purification efficiency.

[0034] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A paint mist treatment system for aircraft paint spraying hangars, characterized in that: The system includes a paint mist collection device, an airflow distribution device, an adsorption and desorption device, and an energy recovery and control device; The paint mist collection device is located around the spraying area and includes a flow guide hood surrounding the spraying area and a multi-stage filter layer arranged coaxially with the outlet of the flow guide hood. A sampling port and a volumetric flow meter are provided at the front end of the outlet of the flow guide hood. Differential pressure taps are provided at the front and rear ends of the multi-stage filter layer, respectively. A transition cavity is provided between the outlet of the flow guide hood and the downstream porous flow equalization plate. The length of the transition cavity is 4 to 6 times the thickness of the porous flow equalization plate. The airflow equalization device is arranged between the paint mist collection device and the adsorption bed, and includes a porous flow equalization plate and a guide grid. The porous flow equalization plate has an opening ratio of 30% to 50% and a pore diameter of 1.5 to 3.0 mm. The guide grid is arranged in front of the porous flow equalization plate and intersects the plate surface at 90°. A dot matrix flow velocity sensor is installed downstream of the porous flow equalization plate. A straight pipe section with a length of 6 to 10 times the hydraulic diameter is installed between the downstream of the porous flow equalization plate and the adsorption inlet. The adsorption and desorption device includes an adsorption bed with partitioned filling using granular activated carbon or honeycomb molecular sieves. Each partition is equipped with inlet and outlet valves, bypass valves, and sampling ports. Temperature monitoring points are set on the bed. Under desorption conditions, an electric heater generates a desorption gas flow at a temperature of 120°C to 150°C, and a vacuum pump maintains the bed pressure at 10 kPa to 30 kPa. The desorption tail gas enters the energy recovery and control device through a branch. The energy recovery and control device includes a plate-fin heat exchanger arranged in the desorption branch. Temperature sensors are respectively installed at the hot side inlet and outlet and the cold side inlet and outlet of the plate-fin heat exchanger. A return branch pipe is provided at the cold side outlet of the plate-fin heat exchanger. The return branch pipe forms a closed loop with the adsorption inlet so that the preheated gas flow can be used as the carrier gas in the next adsorption cycle.

2. The aircraft paint mist treatment system for a hangar as described in claim 1, characterized in that: The multi-stage filter layer comprises a metal mesh layer and a fiber condensation layer from upstream to downstream. The pore size of the metal mesh layer is 0.3 to 0.5 mm, and the thickness of the fiber condensation layer is 10 to 15 mm. The diameter of the sampling port is 10 mm, and the range of the volumetric flow meter is 0 to 500 liters / minute. Each differential pressure tap is 50 mm away from the surface of the corresponding filter layer and is connected to a differential pressure transmitter. The differential pressure signal is converted by the differential pressure transmitter and stored synchronously with the volumetric flow rate and sampling time.

3. The paint mist treatment system for aircraft paint spraying hangars according to claim 2, characterized in that: The transition cavity is a closed cuboid structure; the porous flow equalization plate is made of stainless steel and is sealed and fixed to the pipe wall after being pressed by a frame; the measuring points of the dot matrix flow velocity sensor cover more than 80% of the effective area of ​​the cross section and are used to obtain the average velocity of the cross section; the cross section downstream of the porous flow equalization plate is also provided with a sampling port for capturing paint mist particles through a filter membrane.

4. The paint mist treatment system for aircraft paint spraying hangars according to claim 3, characterized in that: The adsorption bed is divided into multiple independent zones. The adsorbent loading amount, number of zones, and switching threshold of each zone are determined based on the inlet concentration, zone outlet concentration, gas flow volumetric flow rate, sampling time, and adsorbent mass of the zone measured at the sampling port. The zone switching threshold is formed by experimental calibration of the maximum adsorption amount and adsorption rate constant. When the actual adsorption amount of a zone reaches the zone switching threshold, the control signal triggers the switching valve group to complete the switching between adsorption and desorption conditions.

5. The aircraft paint mist treatment system for a hangar according to claim 4, characterized in that: The energy recovery and control device also includes a PLC, which collects the inlet and outlet temperatures of the hot side and the inlet and outlet temperatures of the cold side of the plate-fin heat exchanger, as well as the desorbed gas mass flow rate. Based on the desorbed gas mass flow rate, the gas specific heat capacity at constant pressure, and the inlet and outlet temperatures of the hot and cold sides, the PLC determines the heat recovery efficiency and the system purification removal rate based on the pollutant concentration in the gas flow before the adsorption bed and the pollutant concentration in the gas flow at the outlet of the adsorption bed. The PLC uses the heat recovery efficiency and the system purification removal rate as scheduling criteria to adjust the power of the desorption heater, the speed of the desorption fan, and the opening and closing sequence of the switching valve group.

6. A method for controlling the adsorption and desorption of paint mist in aircraft paint hangars, characterized in that: The paint mist treatment system for an aircraft hangar as described in any one of claims 1 to 5 includes the following steps: S1, During the painting operation, the paint mist collection device is activated to form a directional airflow, which captures paint mist particles at the outlet of the guide hood through the filter membrane, and obtains the paint mist mass, airflow volume flow rate and sampling time captured by the filter membrane, and determines the inlet paint mist concentration based on the paint mist mass, airflow volume flow rate and sampling time. S2, the airflow passes through the transition cavity, guide grid, porous flow equalization plate, dot matrix flow velocity sensor and straight pipe section in sequence before entering the corresponding section of the adsorption bed. The actual adsorption amount of the section is determined based on the inlet paint mist concentration, the section outlet concentration, the airflow volume flow rate, the sampling time and the adsorbent mass of the section. S3, when the actual adsorption amount reaches the partition switching threshold, the adsorption path of the partition is closed and the desorption path of the partition is opened by the switching valve group. The electric heater provides a desorption gas flow at a temperature of 120°C to 150°C, and the vacuum pump maintains the bed pressure at 10 kPa to 30 kPa to desorb the adsorbent in the partition. S4 allows the high-temperature waste gas generated by desorption to enter the plate-fin heat exchanger. The heat recovery efficiency is determined based on the hot-side inlet and outlet temperatures, cold-side inlet and outlet temperatures, and the mass flow rate of the desorbed gas in the plate-fin heat exchanger. A portion of the preheated gas flow from the cold-side outlet of the plate-fin heat exchanger is then guided back to the adsorption inlet via the return branch pipe to serve as the preheated carrier gas for the next cycle.

7. The adsorption-desorption control method for paint mist treatment in aircraft paint hangars according to claim 6, characterized in that: In step S1, the differential pressure before and after the multi-stage filter layer is acquired simultaneously, and the differential pressure signal, airflow volumetric flow rate, and sampling time are stored synchronously. In step S2, the velocity field acquired by the dot matrix flow sensor is used to determine the airflow volumetric flow rate, and the inlet paint mist concentration is used as the input parameter for adsorption capacity determination. The actual adsorption amount is compared with the experimentally calibrated partition switching threshold.

8. The adsorption-desorption control method for paint mist treatment in aircraft paint hangars according to claim 7, characterized in that: In step S3, the desorption energy consumption is determined based on the desorbed gas mass flow rate, gas specific heat capacity, desorbed gas temperature, initial ambient temperature, latent heat of desorption of the target organic component, and the mass of organic matter released during desorption. In step S4, the heat recovery efficiency is correlated with the desorption energy consumption to evaluate the energy efficiency of the desorption process, and the PLC adjusts the heating power and fan speed based on real-time feedback of temperature, humidity, and concentration.

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