Vacuum thermal desorption and ondensation recovery system for volatile organic gases

Abstract

The present invention discloses a vacuum thermal desorption and condensation recovery system for volatile organic gases, which is designed to solve the problems of low efficiency, high energy consumption and poor recovery effect of existing volatile organic gas treatment technology. The system includes a controller, a centralized exhaust tower, and a main exhaust fan. Through the main exhaust fan, an organic waste gas is transported to the centralized exhaust tower, adsorbed by a mobile bed of a spherical adsorbent, and the saturated spherical adsorbent is sent to a vacuum thermal desorption tower for thermal desorption. The desorbed organic waste gas is condensed by a vacuum condenser and recycled to a storage tank, and the desorbed spherical adsorbent is returned for re-adsorption. The system can be operated in single tower or double tower alternately to realize continuous adsorption and desorption. In addition, a pressure regulating device with a vacuum pump is provided for adjusting the vacuum degree in the tower to enhance the desorption efficiency. The system can efficiently process strong airflow and low concentration of organic waste gas to achieve the effects of purifying gas, recovering resources, and reducing operating costs.

Description

[Technical Field]

[0001] This invention relates to the field of waste gas treatment technology, and more specifically, to a vacuum thermal desorption condensation and recovery system for volatile organic gases, which is specifically designed to treat volatile organic gases (VOCs), and can not only purify the gas, but also realize resource recycling and reuse. [Previous Technology]

[0002] Note: Volatile organic gases (VOCs), as a class of organic compounds that easily evaporate at room temperature, are commonly found in many industrial production processes such as chemical processing, coatings, and printing. Once these waste gases are released into the environment, they not only cause air pollution and form photochemical smog, harming the human respiratory and nervous systems, but also waste a large amount of organic resources they contain.

[0003] Existing volatile organic compound (VOC) treatment technologies exhibit numerous drawbacks when dealing with large volumes of low-concentration waste gas. Due to structural and technological limitations, some adsorption devices face difficulties in adsorbent regeneration, hindering continuous regeneration and recycling, forcing the interruption of the entire treatment process and significantly impacting industrial production efficiency. Furthermore, some recovery systems lack precise desorption condition control, resulting in high impurity content and low purity of recovered organic matter, failing to meet reuse requirements, wasting energy and increasing treatment costs. Additionally, using hot air to heat the adsorbent in the desorption tower incurs extremely high equipment and operating costs, and excessive concentrations pose a risk of combustion or even explosion. Currently, most adsorption-based VOC treatment processes involve high-temperature desorption of VCOs, followed by incineration in an incinerator, leading to increased carbon emissions and making recycling impossible.

[0004] Therefore, developing a high-efficiency, energy-saving, and continuously operating vacuum thermal desorption and condensation recovery system for volatile organic gases is of vital practical significance for improving the level of waste gas treatment, reducing environmental pollution, and realizing resource recycling. [Summary of the Invention]

[0005] This invention aims to provide a vacuum thermal desorption condensation and recovery system for volatile organic gases. This system can efficiently concentrate, adsorb, thermally desorb, and condense volatile organic gases under harsh conditions of large air volume and low concentration exhaust gas. By achieving continuous adsorption and desorption operations, it significantly improves waste gas treatment efficiency and resource recovery rate, effectively reducing system operating costs.

[0006] This invention provides a vacuum thermal desorption and condensation recovery system for volatile organic gases. The system includes a controller, a waste gas collection tower, a main exhaust fan, a spherical adsorbent fluidized bed, a main adsorbent conveying device, a first vacuum thermal desorption tower, a first heating valve, a first adsorbent conveying device, a first vacuum valve, a first vacuum breaking valve, a first vacuum condenser, a vacuum pump, and a first recovery storage tank. The waste gas collection tower is connected to and controlled by the controller. The main exhaust fan is connected to and controlled by the controller and connected to the waste gas collection tower. The main exhaust fan is used to transport an organic waste gas, wherein the organic waste gas is a volatile organic gas (VOCs), through airflow to the waste gas collection tower. A spherical adsorbent fluidized bed is disposed inside the waste gas collection tower. This fluidized bed contains multiple spherical adsorbents and is used to concentrate and adsorb the organic waste gas under conditions of high air volume (12,000 CMH~150,000 CMH) and low concentration exhaust gas. The spherical adsorbents are spherical resins or spherical activated carbon. A main adsorbent conveying device is disposed at the bottom of the waste gas collection tower and is connected to and controlled by the controller. A first vacuum thermal desorption tower is connected to and controlled by the controller and is also connected to the main adsorbent conveying device. The first vacuum thermal desorption tower receives the adsorbed saturated spherical adsorbents, and the main adsorbent conveying device conveys the adsorbed saturated spherical adsorbents from the spherical adsorbent fluidized bed to the first vacuum thermal desorption tower. A first heating valve is connected to and controlled by the controller and is connected to the first vacuum thermal desorption tower. The first heating valve is connected to a heat source for supplying heating. A first adsorbent delivery device, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, is used to deliver the desorbed spherical adsorbents within the first vacuum thermal desorption tower to the spherical adsorbent fluidized bed. A first vacuum valve, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower. A first vacuum breaking valve, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, is used to break the vacuum state within the first vacuum thermal desorption tower. A first vacuum condenser, connected to and controlled by the controller, is connected between the first vacuum valve and the second vacuum valve. A vacuum pump, connected to and controlled by the controller, is used to evacuate the first vacuum thermal desorption tower to achieve the required vacuum level within the tower. The first recovery storage tank is connected to the first vacuum condenser. The first vacuum condenser is used to condense the desorbed gaseous organic waste gas into a recovery liquid and discharge it into the first recovery storage tank when the pressure inside the first vacuum thermal desorption tower reaches -10 kPa to -200 kPa and the condensation temperature reaches 0 to 5 degrees Celsius during the desorption process of the first vacuum thermal desorption tower.The controller enables the main adsorbent conveying device to transport the saturated spherical adsorbent to the first vacuum thermal desorption tower. After the conveying reaches the high material level, the conveying stops. Then, the controller closes all valves corresponding to the first vacuum thermal desorption tower and simultaneously opens the first vacuum valve. The vacuum pump pumps out the gas, and the first heating valve supplies the heat source and heats the gas to 50-200 degrees Celsius for desorption. When the vacuum pump pumps out the gas, the first vacuum condenser reaches -10 kPa to -200 kPa and the condensation temperature is between -2 and 5 degrees Celsius. At this point, the organic waste gas begins to condense into the recovered liquid and is discharged into the first recovery storage tank.

[0007] In one embodiment of the present invention, the first vacuum thermal desorption tower after desorption is completed breaks the vacuum state through the first vacuum breaking valve, and the controller then transports the desorbed spherical adsorbents to the spherical adsorbent fluidized bed through the first adsorbent conveying device for re-adsorption.

[0008] In one embodiment of the present invention, the vacuum thermal desorption condensation and recovery system for volatile organic gases further includes a second vacuum thermal desorption tower, a second heating valve, a second adsorbent conveying device, a second vacuum valve, and a second vacuum breaking valve. The second vacuum thermal desorption tower is connected to and controlled by the controller and is also connected to the main adsorbent conveying device. The second vacuum thermal desorption tower is used to receive the adsorbed saturated spherical adsorbents, wherein the main adsorbent conveying device is used to convey the adsorbed saturated spherical adsorbents from the spherical adsorbent fluidized bed to the second vacuum thermal desorption tower. The second heating valve is connected to and controlled by the controller and is also connected to the second vacuum thermal desorption tower. The second heating valve is connected to the heat source and is used to supply heating. The second adsorbent conveying device is connected to and controlled by the controller. The second adsorbent conveying device is used to convey the desorbed spherical adsorbents in the second vacuum thermal desorption tower to the spherical adsorbent fluidized bed. A second vacuum valve, connected to and controlled by the controller, and connected to the second vacuum thermal desorption tower. A second vacuum breaking valve, connected to and controlled by the controller, and connected to the second vacuum thermal desorption tower, is used to break the vacuum state inside the second vacuum thermal desorption tower. After the first vacuum thermal desorption tower completes the thermal desorption operation, the corresponding valve is closed. Then, the controller causes the main adsorbent conveying device to transport the saturated spherical adsorbent to the second vacuum thermal desorption tower to a high level and then stops the conveying. Afterwards, the controller closes all valves corresponding to the second vacuum thermal desorption tower and simultaneously opens the second vacuum valve. The vacuum pump performs evacuation, and the second heating valve supplies the heat source and heats the gas to 50-200 degrees Celsius for desorption. When the vacuum pump is evacuating, the organic waste gas is condensed into the recovery liquid by the first vacuum condenser when the pressure reaches -10 kPa to -200 kPa and the condensation temperature is -2 to 5 degrees Celsius, and is discharged into the first recovery storage tank.

[0009] In one embodiment of the present invention, the second vacuum thermal desorption tower after desorption is completed breaks the vacuum state through the second vacuum breaking valve, and the controller then transports the desorbed spherical adsorbents to the spherical adsorbent fluidized bed for re-adsorption via the second adsorbent conveying device.

[0010] In one embodiment of the present invention, the saturated spherical adsorbents are thermally desorbed in the first vacuum thermal desorption tower or the second vacuum thermal desorption tower. After desorption, the spherical adsorbents are gas-transported back to the spherical adsorbent fluidized bed through the first adsorbent conveying device or the second adsorbent conveying device to re-adsorb the organic waste gas. The process is repeated between the two towers to achieve continuous adsorption and desorption, emission compliance, and recovery of the organic waste gas.

[0011] In one embodiment of the present invention, the vacuum thermal desorption condensation and recovery system for volatile organic gases further includes a pressure regulating device. The pressure regulating device is connected to the first vacuum condenser and is used in conjunction with the vacuum pump to adjust the vacuum level and change the internal pressure within the first and second vacuum thermal desorption towers, thereby breaking the phase equilibrium of the organic waste gas attached to the spherical adsorbents and further facilitating the detachment of the organic waste gas from the micropores of the spherical adsorbents.

[0012] In one embodiment of the present invention, the particle size of the spherical adsorbent is 0.3 mm to 2 mm.

[0013] In one embodiment of the present invention, the organic waste gas is separated from the micropores of the spherical adsorbent and concentrated by a factor of 1,000 to 5,000.

[0014] In summary, the vacuum thermal desorption and condensation recovery system for volatile organic gases disclosed in this invention can bring the following benefits: 1. High-efficiency adsorption and recovery: Under conditions of large air volume (12,000 CMH ~ 150,000 CMH) and low concentration exhaust gas, the system of this invention can still efficiently concentrate, adsorb, and condense volatile organic gases. The concentration factor of organic waste gas TA separated from the micropores of the spherical adsorbent BT can reach 1,000 ~ 5,000 times, greatly improving the concentration of the recovered liquid and the resource recovery rate. 2. Continuous operation: By setting up two vacuum thermal desorption towers and switching between the two towers, the system realizes continuous regeneration and recycling of the adsorbent, ensuring continuous adsorption and desorption operation of the system. This not only improves the efficiency of waste gas treatment but also minimizes the impact on production. 3. Precise control: The controller can precisely control the operating parameters of each device, such as temperature, pressure, and flow rate. Through real-time monitoring and adjustment, it ensures that the system always operates under optimal conditions, improving the stability and reliability of waste gas treatment. 4. Energy Saving and Consumption Reduction: This system adopts vacuum thermal desorption technology, which lowers the desorption temperature and effectively reduces energy consumption. Furthermore, the application of a pressure regulating device further improves desorption efficiency and reduces system operating costs.

[0015] The following detailed description of specific embodiments will make it easier to understand the purpose, technical content, features and effects of the present invention.

Implementation Method

[0016] Previous adsorption methods for treating organic waste gas mostly involved adsorption of volatile organic compounds (VCOs) followed by high-temperature desorption and incineration, resulting in increased carbon emissions and making recycling impossible. This invention uniquely utilizes a highly efficient concentration technology with a fluidized bed and low pressure loss equipment, simultaneously employing efficient vacuum heating for desorption and condensation. Because the vacuum principle lowers the boiling point and reduces van der Waals forces, high-temperature desorption is unnecessary to prevent VOCs from breaking bonds in the adsorbent and generating other VOCs. Furthermore, condensation under vacuum conditions does not require -20°C; condensation with cold water at 0-5°C is sufficient, achieving energy saving and carbon reduction. In addition, previous technologies used hot air to heat the spherical adsorbent in the desorption tower, resulting in extremely high equipment and operating costs, and posing a risk of combustion or even explosion if the concentration is too high. This invention utilizes a heat exchanger within a vacuum thermal desorption tower to heat the adsorbent to 100-140 degrees Celsius for desorption. The vacuum thermal desorption tower (VO2) provides more uniform heating. Heating the adsorbent to be desorbed increases its temperature, resulting in more uniform heating. Simultaneously, the vacuum level is changed from -10 kPa to -200 kPa, making it easier for organic waste gas to detach from the spherical adsorbent, leading to excellent desorption efficiency. Furthermore, it requires no significant calorific value consumption.

[0017] Please refer to Figure 1, which is a schematic diagram of the vacuum thermal desorption and condensation recovery system for volatile organic gases of the present invention. As shown in the figure, the vacuum thermal desorption and condensation recovery system 100 for volatile organic gases includes a controller 101, a waste gas collection tower 102, a main exhaust fan 103, a spherical adsorbent fluidized bed 104, a main adsorbent conveying device 105, a first vacuum thermal desorption tower 106, a first heating valve 107, a first adsorbent conveying device 108, a first vacuum valve 109, a first vacuum breaking valve 110, a first vacuum condenser 111, a vacuum pump 112, and a first recovery storage tank 113. The waste gas collection tower 102 is connected to and controlled by the controller 101, and is also connected to the main exhaust fan 103. A main exhaust fan 103, connected to and controlled by the controller 101, and connected to the waste gas collection tower 102, is used to transport organic waste gas TA to the waste gas collection tower 102 through airflow. The organic waste gas TA is volatile organic compounds (VOCs). A spherical adsorbent fluidized bed 104 is disposed inside the waste gas collection tower 102. The spherical adsorbent fluidized bed 104 has multiple spherical adsorbents BT and is used to concentrate and adsorb the organic waste gas TA under conditions of high airflow (12,000 CMH to 150,000 CMH) and low concentration exhaust gas. The spherical adsorbents BT are spherical resins or spherical activated carbon, and the particle size of the spherical adsorbents BT is 0.3 mm to 2 mm. A main adsorbent conveying device 105 is disposed inside the waste gas collection tower 102 and is connected to and controlled by the controller 101.

[0018] A first vacuum thermal desorption tower 106, connected to and controlled by the controller 101, and connected to the main adsorbent delivery device 105, is used to receive the adsorbed saturated spherical adsorbents BT, wherein the main adsorbent delivery device 105 is used to transport the adsorbed saturated spherical adsorbents BT from the spherical adsorbent fluidized bed 104 to the first vacuum thermal desorption tower 106. A first heating valve 107, connected to and controlled by the controller 101, and connected to the first vacuum thermal desorption tower 106, is connected to a heat source HS and used to supply heating. A first adsorbent delivery device 108, connected to and controlled by the controller 101, and connected to the first vacuum thermal desorption tower 106, is used to transport the desorbed spherical adsorbents BT in the first vacuum thermal desorption tower 106 to the spherical adsorbent fluidized bed 104. A first vacuum valve 109 is connected to and controlled by the controller 101 and is also connected to the first vacuum thermal desorption tower 106. A first vacuum breaking valve 110 is connected to and controlled by the controller 101 and is also connected to the first vacuum thermal desorption tower 106. The first vacuum breaking valve 110 is used to break the vacuum state inside the first vacuum thermal desorption tower 106.

[0019] A first vacuum condenser 111 is connected to and controlled by the controller 101, and is also connected to the first vacuum valve 109. A vacuum pump 112 is connected to and controlled by the controller 101, and is used to evacuate the first vacuum thermal desorption tower 106 to achieve the required vacuum level. A first recovery storage tank 113 is connected to the first vacuum condenser 111, and is used during the desorption process of the first vacuum thermal desorption tower 106, when the pressure inside the first vacuum thermal desorption tower 106 reaches -10KPa to -200KPa and the condensation temperature reaches -2 to 5 degrees Celsius, to condense the desorbed gaseous organic waste gas TA into a recovery liquid BL and discharge it into the first recovery storage tank 113. It should be noted that the present invention further includes a refrigeration unit 122 connected to a first vacuum condenser 111, which is capable of reducing the condensing temperature to below zero degrees Celsius, wherein the refrigeration unit 122 includes a heat exchanger and a refrigerant compressor.

[0020] Subsequently, the controller 101 causes the main adsorbent conveying device 105 to convey the saturated spherical adsorbent BT to the first vacuum thermal desorption tower 106. After reaching the high material level, the conveying stops. Then, the controller 101 closes all valves corresponding to the first vacuum thermal desorption tower 106 and simultaneously opens the first vacuum valve 109 and the vacuum pump 112 to pump air. At the same time, the first heating valve 107 supplies the heat source HS and heats it to 100-140 degrees Celsius for desorption. When the vacuum pump 112 pumps air, the organic waste gas TA is condensed into the recovery liquid BL by the first vacuum condenser 111 when the pressure reaches -10KPa to -200KPa and the condensation temperature is between 0 and 5 degrees Celsius. This liquid is then discharged into the first recovery storage tank 113. Next, the first vacuum thermal desorption tower 106, after desorption is completed, breaks the vacuum state through the first vacuum breaking valve 110. The controller 101 then sends the desorbed spherical adsorbent BT to the spherical adsorbent fluidized bed 104 via the first adsorbent conveying device 108 for re-adsorption. During this process, the absence of oxygen inside can effectively prevent the risk of combustion.

[0021] The vacuum thermal desorption condensation and recovery system 100 for volatile organic gases further includes a second vacuum thermal desorption tower 114, a second heating valve 115, a second adsorbent delivery device 116, a second vacuum valve 117, and a second vacuum breaking valve 118. A first vacuum condenser 111 is connected to and controlled by the controller 101, and is connected between the first vacuum valve 109 and the second vacuum valve 117. The second vacuum thermal desorption tower 114 is connected to and controlled by the controller 101, and is connected to the main adsorbent delivery device 105. The second vacuum thermal desorption tower 114 is used to receive the adsorbed saturated spherical adsorbents BT, wherein the main adsorbent delivery device 105 is used to transport the adsorbed saturated spherical adsorbents BT from the spherical adsorbent fluidized bed 104 to the second vacuum thermal desorption tower 114. A second heating valve 115, connected to and controlled by the controller 101, and connected to the second vacuum thermal desorption tower 114, is connected to the heat source HS and used to supply heating. A second adsorbent delivery device 116, connected to and controlled by the controller 101, is used to deliver the desorbed spherical adsorbents BT in the second vacuum thermal desorption tower 114 to the spherical adsorbent fluidized bed 104.

[0022] A second vacuum valve 117 is connected to and controlled by the controller 101 and is also connected to the second vacuum thermal desorption tower 114. A second vacuum breaking valve 118 is connected to and controlled by the controller 101 and is also connected to the second vacuum thermal desorption tower 114. The second vacuum breaking valve 118 is used to break the vacuum state inside the second vacuum thermal desorption tower 114. After the first vacuum thermal desorption tower 106 completes the thermal desorption operation, the corresponding valves are closed. Then, the controller 101 causes the main adsorbent conveying device 105 to transport the saturated spherical adsorbent BT to the second vacuum thermal desorption tower 114. After the conveying reaches the high material level, the conveying stops. Then, the controller 101 closes all valves corresponding to the second vacuum thermal desorption tower 114 and simultaneously opens the second vacuum valve 117 and the vacuum pump 112 to pump air. At the same time, the second heating valve 115 supplies the heat source HS and heats it to 50-200 degrees Celsius for desorption. When the vacuum pump 112 pumps air, the first vacuum condenser 111 reaches -10KPa to -200KPa and the condensation temperature is between -2 and 5 degrees Celsius. The organic waste gas TA is then condensed into the recovery liquid BL and discharged into the first recovery storage tank 113. After desorption is completed, the second vacuum thermal desorption tower 114 breaks the vacuum state through the second vacuum breaking valve 118. The controller 101 then transports the desorbed spherical adsorbent BT to the spherical adsorbent fluidized bed 104 via the second adsorbent conveying device 116 for re-adsorption. During this process, the absence of oxygen inside can effectively prevent the risk of combustion.

[0023] In other words, the spherical adsorbents BT that have been saturated with adsorption are thermally desorbed in the first vacuum thermal desorption tower 106 or the second vacuum thermal desorption tower 114. After desorption, the spherical adsorbents BT are gas-transported back to the spherical adsorbent fluidized bed 104 through the first adsorbent conveying device 108 or the second adsorbent conveying device 116 to re-adsorb the organic waste gas TA. In this way, the system switches and circulates between the two towers to achieve continuous adsorption and desorption, emission compliance and recovery of the organic waste gas TA.

[0024] It is worth mentioning that the vacuum thermal desorption condensation and recovery system 100 for volatile organic gases further includes a pressure regulating device 119. The pressure regulating device 119 is connected to the first vacuum condenser 111. This device 119 works in conjunction with the vacuum pump 112 to adjust the vacuum level and change the internal pressure within the first vacuum thermal desorption tower 106 and the second vacuum thermal desorption tower 114, thereby breaking the phase equilibrium of the organic waste gas TA attached to the spherical adsorbents BT, and further facilitating the detachment of the organic waste gas TA from the micropores of the spherical adsorbents BT. The concentration factor of the organic waste gas TA detaching from the micropores of the spherical adsorbents BT is 1,000 to 5,000 times.

[0025] In this invention, the vacuum thermal desorption condensation recovery system 100 for volatile organic gases is designed to treat volatile organic gases (VOCs). Through steps such as adsorption, thermal desorption and condensation recovery, it achieves the dual goals of waste gas purification and resource recovery. The following will explain its operating principle in detail from the perspectives of single-tower and dual-tower modes.

[0026] [Working Principle of Single Tower Mode]

[0027] Adsorption Stage: During industrial production, the continuously generated organic waste gas TA is guided to the main exhaust fan 103 via pipelines. Under the control of the controller 101, the main exhaust fan 103 operates at a stable power, generating a strong suction force to quickly transport the organic waste gas TA to the waste gas collection tower 102. Inside the waste gas collection tower 102, the organic waste gas TA comes into full contact with the spherical adsorbent BT filled in the spherical adsorbent fluidized bed 104. The particle size of the spherical adsorbent BT is between 0.3 mm and 2 mm, possessing a very large specific surface area. Through van der Waals forces, the volatile organic gas molecules in the organic waste gas TA are adsorbed onto the microporous surface of the spherical adsorbent BT, achieving preliminary purification and concentration adsorption of the organic waste gas TA.

[0028] Desorption Stage: As the adsorption process continues, the spherical adsorbent BT gradually reaches adsorption saturation. At this time, the controller 101 receives a saturation signal from the spherical adsorbent fluidized bed 104 and immediately issues a command to start the main adsorbent conveying device 105. The main adsorbent conveying device 105 conveys the saturated spherical adsorbent BT to the first vacuum thermal desorption tower 106. When the spherical adsorbent BT in the first vacuum thermal desorption tower 106 reaches a preset high level, the main adsorbent conveying device 105 stops operating under the control of the controller 101. Subsequently, the controller 101 orderly closes all valves connected to the first vacuum thermal desorption tower 106 to ensure the system's airtightness. Next, the first vacuum valve 109 is opened, and the vacuum pump 112 is started simultaneously. The vacuum pump 112 begins to evacuate air from the first vacuum thermal desorption tower 106 to reduce the pressure inside the tower. At the same time, the controller 101 controls the first heating valve 107 to open and connect it to the hot gas source HS. The high-temperature gas generated by the heat source HS enters the first vacuum thermal desorption tower 106, raising the temperature inside the tower to 50-200 degrees Celsius. Under the combined effects of vacuum and heating, the organic waste gas TA molecules adsorbed in the micropores of the spherical adsorbent BT gain sufficient energy to overcome the adsorption force and desorb from the surface of the spherical adsorbent BT, existing in gaseous form inside the first vacuum thermal desorption tower 106.

[0029] Condensation and Recovery Stage: The gaseous organic waste gas TA desorbed from the spherical adsorbent BT is drawn into the first vacuum condenser 111 by the suction force of the vacuum pump 112 through the first vacuum valve 109. When the pressure inside the first vacuum thermal desorption tower 106 reaches -10KPa to -200KPa, and the condensation temperature inside the first vacuum condenser 111 reaches -2 to 5 degrees Celsius, the gaseous organic waste gas TA undergoes a phase change upon cooling and condenses into a recovery liquid BL. The recovery liquid BL flows into the first recovery storage tank 113 for storage under gravity to achieve the recovery of organic waste gas TA.

[0030] Adsorbent Regeneration Stage: When the desorption process is completed, the spherical adsorbent BT in the first vacuum thermal desorption tower 106 regains its adsorption activity. At this time, the controller 101 controls the first vacuum breaking valve 110 to open, allowing outside air to enter the first vacuum thermal desorption tower 106 and breaking the vacuum state inside the first vacuum thermal desorption tower 106. Subsequently, the controller 101 starts the first adsorbent conveying device 108 to transport the regenerated spherical adsorbent BT back to the spherical adsorbent fluidized bed 104, so that it can re-participate in the adsorption process and realize the recycling of the adsorbent.

[0031] [Dual-Tower Mode Working Principle]

[0032] First tower adsorption, second tower desorption: The main exhaust fan 103 continuously transports organic waste gas TA to the waste gas collection tower 102, where it is adsorbed and purified in the spherical adsorbent fluidized bed 104. Simultaneously, after the first vacuum thermal desorption tower 106 completes the previous round of thermal desorption, its corresponding valve is closed under the control of the controller 101. Under the instruction of the controller 101, the main adsorbent conveying device 105 transports the saturated spherical adsorbent BT to the second vacuum thermal desorption tower 114. When the spherical adsorbent BT in the second vacuum thermal desorption tower 114 reaches a high level, the main adsorbent conveying device 105 stops conveying. Then, the controller 101 closes all valves connected to the second vacuum thermal desorption tower 114, opens the second vacuum valve 117, and starts the vacuum pump 112 to evacuate the second vacuum thermal desorption tower 114. At the same time, the controller 101 controls the second heating valve 115 to open, introducing high-temperature gas from the heat source HS, raising the temperature inside the second vacuum thermal desorption tower 114 to 50~200 degrees Celsius, and carrying out thermal desorption operations.

[0033] First tower desorption, second tower adsorption: After the second vacuum thermal desorption tower 114 completes the thermal desorption operation, the controller 101 closes all its corresponding valves. At this time, the spherical adsorbent BT in the spherical adsorbent fluidized bed 104 has reached adsorption saturation. Under the control of the controller 101, the main adsorbent conveying device 105 conveys the adsorbed saturated spherical adsorbent BT to the first vacuum thermal desorption tower 106. The above desorption, condensation recovery and adsorbent regeneration process is repeated to realize the switching cycle between the first vacuum thermal desorption tower 106 and the second vacuum thermal desorption tower 114, thereby ensuring the continuous operation of the system and greatly improving the treatment efficiency of organic waste gas TA.

[0034] [Auxiliary Working Principle of Voltage Regulator]

[0035] The pressure regulating device 119 is connected to the first vacuum condenser 111 and works in conjunction with the vacuum pump 112. During the thermal desorption process, the pressure regulating device 119 monitors the pressure changes in the first vacuum thermal desorption tower 106 and the second vacuum thermal desorption tower 114 in real time, and finely adjusts the pressure inside the towers according to the preset pressure range. By precisely controlling the pressure inside the towers, the adsorption equilibrium of organic waste gas TA on the spherical adsorbent BT is broken, making it easier for organic waste gas TA molecules to detach from the micropores of the spherical adsorbent BT, further improving the desorption efficiency and reducing system energy consumption.

[0036] Furthermore, in a closed environment, the state in which the liquid and gas phases of the same substance reach dynamic equilibrium (the number of molecules escaping from the liquid phase per unit time is equal to the number of molecules returning from the gas phase to the liquid phase) is called equilibrium. The liquid phase in equilibrium is called a saturated liquid, and the gas phase is called a saturated vapor pressure. The equilibrium state of a substance is related to factors such as pressure and temperature. When pressure and temperature change, the equilibrium will be broken, and when the pressure, temperature, and other parameters stabilize, the equilibrium state will be re-established. The equilibrium state corresponds to the temperature and pressure of the substance. However, during the desorption of adsorbents, it is common to encounter a phenomenon where the desorption temperature is higher than the boiling point of the adsorbate (organic waste gas), but the desorption effect is poor. The reason for this is that inside the adsorbent, due to the fine coagulation phenomenon, the adsorbate undergoes "chemical adsorption." A phase change should occur, but it does not. Chemical adsorption phenomena include: supersaturated vapor, supercooled liquid, superheated liquid, and supersaturated solution.

[0037] The desorption of spherical adsorbent BT requires heating and changing the vacuum level to effectively change the van der Waals force or chemisorption, thereby effectively desorbing the adsorbent.

[0038] In this invention, the VOCs attached to the spherical adsorbent BT are continuously adjusted by changing the vacuum degree inside the first vacuum thermal desorption towers 106 and 114, that is, by changing the external pressure of the spherical adsorbent BT, the van der Waals force can be broken, thereby continuously breaking the phase equilibrium and causing the VOCs accumulated inside the micropores to desorb in the shortest time.

[0039] In simple terms, existing technologies perform desorption under a stable low-pressure state within the thermal desorption tower. The organic waste gas adheres to the adsorbent in a relatively balanced state, making it difficult for the organic waste gas to escape from the micropores of the adsorbent, resulting in poor desorption performance. This invention utilizes a vacuum pump 112 and a pressure regulating device 119 in combination with a first vacuum condenser 111 to maintain a vacuum state within the first vacuum thermal desorption tower 106 or the second vacuum thermal desorption tower 114. This breaks the relative balance of VOCs adsorbed on the spherical adsorbent BT, allowing the organic waste gas TA to easily escape from the micropores of the spherical adsorbent BT, resulting in high desorption efficiency and better desorption effect.

[0040] Furthermore, the vacuum thermal desorption condensation and recovery system 100 for volatile organic gases further includes a second vacuum condenser 120 and a second recovery storage tank 121. The second recovery storage tank 121 is connected to the second vacuum condenser 120, and the second vacuum condenser 120 is connected to the vacuum pump 112. The second vacuum condenser 120 and the second recovery storage tank 121 have the same function as the first vacuum condenser 111 and the first recovery storage tank 113, and will not be described again here.

[0041] In terms of expansion capabilities, the vacuum thermal desorption condensation and recovery system for volatile organic gases disclosed in this invention can be expanded from the two vacuum thermal desorption towers mentioned above to three, four, or even more vacuum thermal desorption towers. The operating mechanisms of the three or more towers can be understood by referring to the operating mechanisms of the single tower and dual tower mentioned above, and will not be repeated here.

[0042] In summary, the vacuum thermal desorption and condensation recovery system for volatile organic gases disclosed in this invention can bring the following benefits: 1. High-efficiency adsorption and recovery: Under conditions of large air volume (12,000 CMH ~ 150,000 CMH) and low concentration exhaust gas, the system of this invention can still efficiently concentrate, adsorb, and condense volatile organic gases. The concentration factor of organic waste gas TA separated from the micropores of the spherical adsorbent BT can reach 1,000 ~ 5,000 times, greatly improving the concentration of the recovered liquid and the resource recovery rate. 2. Continuous operation: By setting up two vacuum thermal desorption towers and switching between the two towers, the system realizes continuous regeneration and recycling of the adsorbent, ensuring continuous adsorption and desorption operation of the system. This not only improves the waste gas treatment efficiency but also minimizes the impact on production. 3. Precise control: The controller can precisely control the operating parameters of each device, such as temperature, pressure, and flow rate. Through real-time monitoring and adjustment, it ensures that the system always operates under optimal conditions, improving the stability and reliability of waste gas treatment. 4. Energy Saving and Consumption Reduction: This system adopts vacuum thermal desorption technology, which lowers the desorption temperature and effectively reduces energy consumption. Furthermore, the application of a pressure regulating device further improves desorption efficiency and reduces system operating costs.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, all equivalent variations or modifications made in accordance with the features and spirit described in the claims of the present invention should be included within the scope of the patent application of the present invention. [Simplified Explanation of the Diagram]

[0044] The first figure is a schematic diagram of the vacuum thermal desorption and condensation recovery system for volatile organic gases of the present invention.

Claims

1. A vacuum thermal desorption condensation and recovery system for volatile organic gases, comprising: One controller; A waste gas collection tower, which is connected to and controlled by the controller; A main exhaust fan, connected to and controlled by the controller, and connected to the waste gas collection tower, is used to transport organic waste gas, wherein the organic waste gas is volatile organic compounds (VOCs), through airflow to the waste gas collection tower; a spherical adsorbent fluidized bed is disposed inside the waste gas collection tower, the spherical adsorbent fluidized bed has multiple spherical adsorbents, and is used to concentrate and adsorb the organic waste gas under conditions of large air volume (12,000 CMH~150,000 CMH) and low concentration exhaust gas, wherein the spherical adsorbents are spherical resins or spherical activated carbons; a main adsorbent conveying device is disposed inside the waste gas collection tower, and the main adsorbent conveying device is connected to and controlled by the controller; A first vacuum thermal desorption tower, connected to and controlled by the controller, and connected to the main adsorbent delivery device, the first vacuum thermal desorption tower for receiving the adsorbent saturated spherical adsorbents, wherein the main adsorbent delivery device is used to transport the adsorbent saturated spherical adsorbents from the spherical adsorbent fluidized bed to the first vacuum thermal desorption tower; a first heating valve, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first heating valve being connected to a heat source for supplying heating; a first adsorbent delivery device, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first adsorbent delivery device being used to transport the desorbed spherical adsorbents in the first vacuum thermal desorption tower to the spherical adsorbent fluidized bed; a first vacuum valve, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower; A first vacuum breaking valve, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first vacuum breaking valve being used to break the vacuum state inside the first vacuum thermal desorption tower; a first vacuum condenser, connected to and controlled by the controller, and connected to the first vacuum valve; a vacuum pump, connected to and controlled by the controller, the vacuum pump being used to evacuate the first vacuum thermal desorption tower to achieve the required vacuum level inside the tower; A first recovery storage tank is connected to the first vacuum condenser, which is used to condense the desorbed gaseous organic waste gas into a recovery liquid and discharge it to the first recovery storage tank when the pressure inside the first vacuum thermal desorption tower reaches -10 kPa to -200 kPa and the condensation temperature reaches -2 to 5 degrees Celsius during the desorption process of the first vacuum thermal desorption tower; a second vacuum thermal desorption tower is connected to and controlled by the controller and connected to the main adsorbent conveying device, which is used to receive the adsorbed saturated spherical adsorbent, wherein the main adsorbent conveying device is used to convey the adsorbed saturated spherical adsorbent from the spherical adsorbent fluidized bed to the second vacuum thermal desorption tower; a second heating valve is connected to and controlled by the controller and connected to the second vacuum thermal desorption tower, and the second heating valve is connected to the heat source and used to supply heating; A second adsorbent delivery device, connected to and controlled by the controller, for delivering the desorbed spherical adsorbents in the second vacuum thermal desorption tower to the spherical adsorbent fluidized bed; a second vacuum valve, connected to and controlled by the controller, and connected to the second vacuum thermal desorption tower. A second vacuum-breaking valve is connected to and controlled by the controller, and connected to the second vacuum thermal desorption tower. This second vacuum-breaking valve is used to break the vacuum state within the second vacuum thermal desorption tower. After the first vacuum thermal desorption tower completes its thermal desorption operation, the corresponding valve is closed. Then, the controller uses the main adsorbent conveying device to transport the saturated spherical adsorbent to the second vacuum thermal desorption tower until the high material level is reached, at which point the conveying stops. Then, the controller closes all valves corresponding to the second vacuum thermal desorption tower and simultaneously opens the second vacuum valve. The vacuum pump then pumps air, and a second heating valve supplies heat to a source of heat, heating the gas to 50-200 degrees Celsius for desorption. When the vacuum pump pumps air, the first vacuum condenser reaches a pressure of -10 kPa to 200 kPa, and the condensation temperature is between -2 and 5 degrees Celsius. At this point, the organic waste gas begins to condense into a recovered liquid and is discharged into the first recovery storage tank. The controller directs the main adsorbent conveying device to transport the saturated spherical adsorbent to the first vacuum thermal desorption tower. Once the level reaches a high point, the conveying stops. The controller then closes all valves corresponding to the first vacuum thermal desorption tower and simultaneously opens the first vacuum valve. A vacuum pump evacuates the tower, while a first heating valve supplies heat to 50-200 degrees Celsius for desorption. While the vacuum pump is evacuating, the first vacuum condenser reaches a pressure of -10 kPa to -200 kPa, and the condensation temperature is between -2 and 5 degrees Celsius. At this point, the organic waste gas is condensed into a recovery liquid and discharged into the first recovery storage tank. The first vacuum thermal desorption tower, after desorption, breaks the vacuum through the first vacuum breaking valve. The controller then transports the desorbed spherical adsorbent to the spherical adsorbent fluidized bed via the first adsorbent conveying device for re-adsorption. The second vacuum thermal desorption tower, after desorption is completed, breaks the vacuum state through the second vacuum breaking valve. The controller then transports the desorbed spherical adsorbents to the spherical adsorbent fluidized bed via the second adsorbent conveying device for re-adsorption.

2. The vacuum thermal desorption and condensation recovery system for volatile organic gases as described in claim 1, wherein the spherical adsorbents saturated with adsorption are thermally desorbed in the first vacuum thermal desorption tower or the second vacuum thermal desorption tower, and then the desorbed spherical adsorbents are gas-transported back to the spherical adsorbent fluidized bed through the first adsorbent conveying device or the second adsorbent conveying device to re-adsorb the organic waste gas. The system switches and circulates between the two towers in this way to achieve continuous adsorption and desorption, emission compliance, and recovery of the organic waste gas.

3. The vacuum thermal desorption condensation and recovery system for volatile organic gases as described in claim 1 further includes: A pressure regulating device is connected to the first vacuum condenser. The pressure regulating device is used in conjunction with the vacuum pump to adjust the vacuum level and change the internal pressure in the first vacuum thermal desorption tower and the second vacuum thermal desorption tower, so as to break the phase equilibrium of the organic waste gas attached to the spherical adsorbents, and further make the organic waste gas easier to detach from the micropores of the spherical adsorbents.

4. The vacuum thermal desorption condensation and recovery system for volatile organic gases as described in claim 1, wherein the particle size of the spherical adsorbent is 0.3 mm to 2 mm.

5. The vacuum thermal desorption condensation and recovery system for volatile organic gases as described in claim 1, wherein the organic waste gas is separated from the micropores of the spherical adsorbents and concentrated by a factor of 1,000 to 5,000.

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