Vacuum thermal desorption condensation recovery system for volatile organic gas

Abstract

The invention provides a vacuum thermal desorption condensation recovery system for volatile organic gas, and aims to solve the problems of low efficiency, high energy consumption, poor recovery effect and the like of the existing volatile organic gas treatment technology. The system comprises a controller, a waste gas concentration tower, a main exhaust fan and the like. Organic waste gas is conveyed to the waste gas concentration tower through the main exhaust fan and is adsorbed by the spherical adsorbent fluid bed, and the spherical adsorbent saturated in adsorption is conveyed to the vacuum thermal desorption tower for thermal desorption. The desorbed organic waste gas is condensed by a vacuum condenser and then recovered to a storage tank, and the desorbed spherical adsorbent is returned to be adsorbed again. The system can operate in a single tower or double towers alternately to realize continuous adsorption and desorption. In addition, the pressure regulating device cooperates with the vacuum pump to regulate the vacuum degree in the tower and improve the desorption efficiency. The system can efficiently treat organic waste gas with strong wind quantity and low concentration, and achieves the purposes of purifying gas, recycling resources and reducing operation cost.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and more specifically, to a vacuum thermal desorption condensation recovery system for volatile organic gases (VOCs). The system is specifically designed to treat volatile organic gases (VOCs), not only purifying the gas but also enabling resource recovery and reuse. Background Art

[0002] Volatile organic compounds (VOCs), a class of organic compounds that are easily volatile at room temperature, are commonly found in numerous industrial production processes, including those in the chemical, coating, and printing industries. Once released into the environment, these waste gases not only cause air pollution, forming photochemical smog and harming human respiratory and nervous system health, but also waste the vast amounts of organic resources they contain.

[0003] Existing volatile organic gas treatment technologies have exposed many drawbacks when faced with large air volumes and low-concentration exhaust gases. Due to structural and process limitations, some adsorption devices have difficulty in regenerating the adsorbent, making it difficult to achieve continuous regeneration and recycling, forcing the entire treatment process to be interrupted, greatly affecting the efficiency of industrial production. In addition, some recovery systems lack precise control measures for desorption conditions, and the recovered organic matter has a high impurity content and low purity, making it difficult to meet the requirements for reuse, which wastes energy and increases processing costs. In addition, the use of hot air to heat the adsorbent in the desorption tower has extremely high equipment and operating costs, and the concentration sometimes poses a risk of combustion or even explosion. Currently, most of the processes for treating organic waste gas by adsorption are: VCOs are desorbed by adsorption at high temperatures and then incinerated in an incinerator, resulting in increased carbon emissions and making it impossible to recycle them.

[0004] Therefore, the development of an efficient, energy-saving, and continuously operating volatile organic gas vacuum thermal desorption condensation recovery system is of vital practical significance for improving waste gas treatment levels, reducing environmental pollution, and realizing resource recycling. Summary of the Invention

[0005] The present invention aims to provide a vacuum thermal desorption and condensation recovery system for volatile organic gases. This system can efficiently perform concentrated adsorption, thermal desorption, and condensation recovery operations on volatile organic gases under the demanding conditions of high air volume and low exhaust concentration. By implementing continuous adsorption and desorption operations, it significantly improves waste gas treatment efficiency and resource recovery rates, effectively reducing system operating costs.

[0006] The present invention provides a vacuum thermal desorption, condensation and recovery system for volatile organic gases. The vacuum thermal desorption, condensation and recovery system for volatile organic gases includes a controller, an exhaust gas concentration 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 breaker valve, a first vacuum condenser, a vacuum pump and a first recovery tank. The exhaust gas concentration tower is connected to and controlled by the controller. The main exhaust fan is connected to and controlled by the controller and is also connected to the exhaust gas concentration tower. The main exhaust fan is used to transport an organic waste gas to the exhaust gas concentration tower via an airflow, wherein the organic waste gas is volatile organic compounds (VOCs). A spherical adsorbent fluidized bed is disposed within the exhaust gas concentration tower. The spherical adsorbent fluidized bed contains multiple spherical adsorbents and is used to concentrate and adsorb organic waste gas under high air volume conditions of 12,000 to 150,000 CMH and low-concentration exhaust gas. The multiple spherical adsorbents are spherical resins or spherical activated carbon. A primary adsorbent delivery device is disposed at the bottom of the exhaust gas concentration 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 primary adsorbent delivery device. The first vacuum thermal desorption tower is used to receive the multiple spherical adsorbents that have been saturated with adsorption. The primary adsorbent delivery device is used to transfer the multiple spherical adsorbents that have been saturated with adsorption 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 also connected to the first vacuum thermal desorption tower. The first heating valve is connected to a hot gas source and is used to supply heat. a first adsorbent conveying device, connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first adsorbent conveying device being used to convey the plurality of spherical adsorbents that have completed desorption 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 in the first vacuum thermal desorption tower; a first vacuum condenser, connected to and controlled by the controller, and connected between the first vacuum valve and the second vacuum valve; a vacuum pump, connected to and controlled by the controller, being used to evacuate the first vacuum thermal desorption tower to achieve the desired vacuum level in 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 to the first recovery storage tank during the desorption process of the first vacuum thermal desorption tower when the pressure in the first vacuum thermal desorption tower reaches -10KPa to -200KPa and the condensation temperature reaches 0 to 5 degrees Celsius. The controller is used to enable the main adsorbent conveying device to convey the multiple saturated spherical adsorbents to the first vacuum thermal desorption tower to a high material level and then stop conveying. Then, the controller is used to close all valves corresponding to the first vacuum thermal desorption tower and open the first vacuum valve at the same time. The vacuum pump is used to evacuate air, and at the same time, the hot air source is supplied through the first heating valve and heated to 50-200 degrees Celsius for desorption. When the vacuum pump is evacuating air, it reaches -10KPa to -200KPa through the first vacuum condenser and the condensation temperature is between -2 and 5 degrees Celsius. The organic waste gas begins to condense into the recovery 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 broken into a vacuum state through the first vacuum breaking valve, and the controller then transports the multiple spherical adsorbents after desorption through the first adsorbent transporting device to the spherical adsorbent fluidized bed for re-adsorption.

[0008] In one embodiment of the present invention, the vacuum thermal desorption condensation 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 breaker 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 plurality of saturated spherical adsorbents, wherein the main adsorbent conveying device is used to convey the plurality of 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 hot gas source and is used to supply heat. The second adsorbent conveying device is connected to and controlled by the controller. The second adsorbent conveying device is used to convey the plurality of spherical adsorbents that have completed desorption in the second vacuum thermal desorption tower to the spherical adsorbent fluidized bed. A second vacuum valve is connected to and controlled by the controller, and is also connected to the second vacuum thermal desorption tower. A second vacuum breaker valve is connected to and controlled by the controller, and is also connected to the second vacuum thermal desorption tower. The second vacuum breaker valve is used to break the vacuum state in 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 is used to control the main adsorbent conveying device to convey the plurality of saturated spherical adsorbents to the second vacuum thermal desorption tower to the high material level and then stop conveying. Then, the controller is used to close all valves corresponding to the second vacuum thermal desorption tower and simultaneously open the second vacuum valve. The vacuum pump is used to evacuate the gas. At the same time, the second heating valve supplies the hot gas source and heats it to 50-200 degrees Celsius for desorption. When the vacuum pump is evacuating the gas, the organic waste gas begins to condense into the recovered liquid through the first vacuum condenser when the temperature reaches -10kPa to -200kPa and the condensation temperature is between -2 and 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 broken into a vacuum state through the second vacuum breaking valve, and the controller then transports the multiple spherical adsorbents after desorption to the spherical adsorbent fluidized bed through the second adsorbent transporting device for re-adsorption.

[0010] In one embodiment of the present invention, the plurality of spherical adsorbents that have been saturated with adsorption are subjected to thermal desorption in the first vacuum thermal desorption tower or the second vacuum thermal desorption tower, and then the plurality of spherical adsorbents that have completed desorption are gaseously 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. In this way, switching and circulation are performed 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 and condensation 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 configured to cooperate with the vacuum pump to adjust the vacuum level and internal pressure within the first and second vacuum thermal desorption towers, thereby disrupting the phase equilibrium of the organic waste gas attached to the plurality of spherical adsorbents and further facilitating the release of the organic waste gas from the micropores of the plurality of 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 concentrated by 1,000 to 5,000 times after being separated from the micropores of the plurality of spherical adsorbents.

[0014] In summary, the vacuum thermal desorption condensation recovery system for volatile organic gases disclosed in the present invention can provide the following benefits:

[0015] 1. High-Efficiency Adsorption Recovery: The system of this invention can efficiently concentrate, adsorb, and condense volatile organic gases (VOCs) even at high air volumes of 12,000 to 150,000 CMH and low-concentration exhaust. The organic waste gas (TA) released from the micropores of the spherical adsorbent (BT) can be concentrated 1,000 to 5,000 times, significantly improving the concentration of the recovered liquid and resource recovery rate.

[0016] 2. Continuous Operation: The system uses two vacuum thermal desorption towers and switches between them to achieve continuous regeneration and recycling of the adsorbent, ensuring continuous adsorption and desorption. This not only improves waste gas treatment efficiency but also minimizes the impact on production.

[0017] 3. Precise control: The controller can precisely control the operating parameters of each device, such as temperature, pressure, flow, etc. Through real-time monitoring and adjustment, it ensures that the system always operates under the optimal working conditions, improving the stability and reliability of exhaust gas treatment.

[0018] 4. Energy saving and consumption reduction: This system uses vacuum thermal desorption technology to reduce the desorption temperature and effectively reduce energy consumption. In addition, the application of the pressure regulating device further improves the desorption efficiency and reduces the operating cost of the system.

[0019] The following detailed description is based on specific embodiments to make it easier to understand the purpose, technical content, characteristics and effects achieved by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Schematic diagram of the vacuum thermal desorption condensation recovery system for volatile organic gases of the present invention.

[0021] Explanation of the accompanying reference numerals: 100 - vacuum thermal desorption condensation recovery system for volatile organic gases; 101 - controller; 102 - waste gas concentration tower; 103 - main exhaust fan; 104 - spherical adsorbent fluidized bed; 105 - main adsorbent conveying device; 106 - first vacuum thermal desorption tower; 107 - first heating valve; 108 - first adsorbent conveying device; 109 - first vacuum valve; 110 - first vacuum breaker valve; 111 - first vacuum condenser; 112 - vacuum pump; 113 - first recovery tank; 114 - second vacuum thermal desorption tower; 115 - second heating valve; 116 - second adsorbent conveying device; 117 - second vacuum valve; 118 - second vacuum breaker valve; 119 - pressure regulating device; 120 - second vacuum condenser; 121 - second recovery tank; 122 - refrigeration unit; BT - spherical adsorbent; TA - organic waste gas; HS - hot air source; BL - recovery liquid. DETAILED DESCRIPTION

[0022] Prior adsorption-based organic waste gas treatment processes mostly involve high-temperature desorption of volatile organic compounds (VCOs) through adsorption and subsequent incineration in an incinerator, resulting in increased carbon emissions and precluding recycling. The present invention uniquely utilizes efficient fluidized bed concentration technology and low-pressure-loss equipment, coupled with efficient vacuum heating for desorption and condensation. Because the vacuum lowers the boiling point and reduces van der Waals forces, high-temperature desorption is unnecessary to prevent VOCs from breaking bonds in the adsorbent due to high temperatures, leading to the decomposition of other VOCs. The vacuum-based condensation temperature does not require -20°C; cold water at 0-5°C can condense the waste gas, achieving energy savings and carbon reduction. Furthermore, prior art uses hot air to heat the spherical adsorbent in the desorption tower, resulting in extremely high equipment and operating costs. Excessive concentration poses the risk of combustion or even explosion. The present invention incorporates a heat exchanger within the vacuum thermal desorption tower to heat the adsorbent to 100-140°C for desorption, ensuring more uniform heating within the vacuum thermal desorption tower (V02). The adsorbent to be desorbed is heated to increase its temperature, and the adsorbent is heated more evenly while the vacuum degree is changed from -10KPa to -200KPa. The organic waste gas is more easily separated from the spherical adsorbent, and the desorption effect is good; at the same time, there is no need to consume a large amount of calorific value.

[0023] See also Figure 1 As shown, Figure 1The figure is a schematic diagram of a vacuum thermal desorption, condensation, and recovery system for volatile organic gases according to the present invention. As shown, the vacuum thermal desorption, condensation, and recovery system 100 for volatile organic gases includes a controller 101, an exhaust gas concentration tower 102, a main exhaust fan 103, a spherical adsorbent fluidized bed 104, a main adsorbent delivery device 105, a first vacuum thermal desorption tower 106, a first heating valve 107, a first adsorbent delivery device 108, a first vacuum valve 109, a first vacuum breaker valve 110, a first vacuum condenser 111, a vacuum pump 112, and a first recovery tank 113. The exhaust gas concentration tower 102 is connected to and controlled by the controller 101 and is also connected to the main exhaust fan 103. The main exhaust fan 103 is connected to and controlled by the controller 101 and is also connected to the exhaust gas concentration tower 102. The main exhaust fan 103 is used to transport organic waste gas TA to the exhaust gas concentration tower 102 via airflow, wherein the organic waste gas TA is volatile organic compounds (VOCs). The spherical adsorbent fluidized bed 104 is disposed within the exhaust gas concentration tower 102. The spherical adsorbent fluidized bed 104 comprises a plurality of spherical adsorbents BT and is used to concentrate and adsorb the organic waste gas TA under high air volume conditions of 12,000 to 150,000 CMH and low exhaust concentration. The plurality of spherical adsorbents BT are spherical resins or spherical activated carbons, and the particle size of the spherical adsorbents BT is 0.3 to 2 mm. The main adsorbent delivery device 105 is disposed inside the exhaust gas concentration tower 102 . The main adsorbent delivery device 105 is connected to the controller 101 and is controlled by the controller 101 .

[0024] The first vacuum thermal desorption tower 106 is connected to and controlled by the controller 101 and is also connected to the main adsorbent conveying device 105. The first vacuum thermal desorption tower 106 is used to receive the plurality of saturated spherical adsorbents BT, wherein the main adsorbent conveying device 105 is used to convey the plurality of saturated spherical adsorbents BT from the spherical adsorbent fluidized bed 104 to the first vacuum thermal desorption tower 106. The first heating valve 107 is connected to and controlled by the controller 101 and is also connected to the first vacuum thermal desorption tower 106. The first heating valve 107 is connected to a hot gas source HS and is used to supply heat. A first adsorbent delivery device 108 is connected to and controlled by the controller 101 and is also connected to the first vacuum thermal desorption tower 106. The first adsorbent delivery device 108 is used to deliver the plurality of spherical adsorbents BT that have completed desorption 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 breaker 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 breaker valve 110 is used to break the vacuum state in the first vacuum thermal desorption tower 106.

[0025] 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 a desired vacuum level within the first vacuum thermal desorption tower 106. A first recovery tank 113 is connected to the first vacuum condenser 111 and is used to condense the desorbed gaseous organic waste gas TA into a recovery liquid BL during the desorption process of the first vacuum thermal desorption tower 106 when the pressure within the first vacuum thermal desorption tower 106 reaches -10 kPa to -200 kPa and the condensation temperature reaches -2 to 5 degrees Celsius, and discharge the recovered liquid BL into the first recovery tank 113. It should be noted that the present invention further includes a refrigeration unit 122 connected to the first vacuum condenser 111 to reduce the condensation temperature to below zero degrees, wherein the refrigeration unit 122 includes a heat exchanger and a refrigerant compressor.

[0026] Afterwards, the controller 101 controls the main adsorbent conveying device 105 to convey the plurality of saturated spherical adsorbents BT to the first vacuum thermal desorption tower 106 until the material level reaches a high level and then stops conveying. The controller 101 then 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 evacuate the gas. Simultaneously, the first heating valve 107 supplies the hot gas source HS and heats it to 100-140 degrees Celsius for desorption. When the vacuum pump 112 evacuates the gas, it passes through the first vacuum condenser 111 and reaches a pressure of -10 kPa to -200 kPa, with a condensation temperature of 0-5 degrees Celsius. The organic waste gas TA begins to condense into the recovered liquid BL, which is then discharged into the first recovery storage tank 113. Next, the first vacuum thermal desorption tower 106 that has completed desorption breaks the vacuum state through the first vacuum breaking valve 110, and the controller 101 then transports the multiple spherical adsorbents BT that have completed desorption through the first adsorbent conveying device 108 to the spherical adsorbent fluidized bed 104 for re-adsorption. During this process, the lack of oxygen inside can effectively prevent the risk of combustion.

[0027] The volatile organic gas vacuum thermal desorption condensation recovery system 100 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 breaker valve 118. The 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 configured to receive the plurality of saturated spherical adsorbents BT. The main adsorbent delivery device 105 is configured to deliver the saturated spherical adsorbents BT from the spherical adsorbent fluidized bed 104 to the second vacuum thermal desorption tower 114. A second heating valve 115 is connected to and controlled by the controller 101 and is also connected to the second vacuum thermal desorption tower 114. The second heating valve 115 is connected to the hot gas source HS and is used to supply heat. A second adsorbent delivery device 116 is connected to and controlled by the controller 101 and is used to deliver the plurality of spherical adsorbents BT that have completed desorption in the second vacuum thermal desorption tower 114 to the spherical adsorbent fluidized bed 104.

[0028] The 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. The second vacuum breaker 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 breaker valve 118 is used to break the vacuum state in the second vacuum thermal desorption tower 114. After the first vacuum thermal desorption tower 106 completes the thermal desorption operation, the corresponding valve will be closed. Then, the controller 101 will be used to enable the main adsorbent conveying device 105 to convey the multiple saturated spherical adsorbents BT to the second vacuum thermal desorption tower 114 to the high material level and then stop conveying. Then, the controller 101 will close all valves corresponding to the second vacuum thermal desorption tower 114 and simultaneously open the second vacuum valve 117 and the vacuum pump 112 to perform air extraction. At the same time, the hot air source HS will be supplied through the second heating valve 115 and heated to 50-200 degrees Celsius for desorption. When the vacuum pump 112 is extracting air, it reaches -10KPa to -200KPa through the first vacuum condenser 111 and the condensation temperature is between -2 and 5 degrees Celsius. Then, the organic waste gas TA begins to condense into the recovery liquid BL and is discharged into the first recovery storage tank 113. The second vacuum thermal desorption tower 114 that has completed desorption breaks the vacuum state through the second vacuum breaking valve 118. The controller 101 then transports the multiple spherical adsorbents BT that have completed desorption to the spherical adsorbent fluidized bed 104 through the second adsorbent conveying device 116 for re-adsorption. During this process, the absence of oxygen inside can effectively prevent the risk of combustion.

[0029] In other words, the multiple 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, and then the multiple spherical adsorbents BT that have completed desorption are gaseously 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, switching and circulation are carried out between the two towers to achieve continuous adsorption and desorption, emission compliance and recovery of the organic waste gas TA.

[0030] It is worth noting that the volatile organic gas vacuum thermal desorption condensation recovery system 100 further includes a pressure regulating device 119. This device, connected to the first vacuum condenser 111, is used to coordinate with the vacuum pump 112 to adjust the vacuum level and internal pressure within the first and second vacuum thermal desorption towers 106 and 114, thereby disrupting the phase equilibrium of the organic waste gas TA attached to the plurality of spherical adsorbents BT and further facilitating the release of the organic waste gas TA from the micropores of the spherical adsorbents BT. The organic waste gas TA is concentrated by a factor of 1,000 to 5,000 after being released from the micropores of the spherical adsorbents BT.

[0031] In this invention, the volatile organic gas vacuum thermal desorption and condensation recovery system 100 treats volatile organic gases (VOCs) through adsorption, thermal desorption, and condensation recovery, achieving the dual goals of waste gas purification and resource recovery. The following details its operating principles from both single-tower and dual-tower modes.

[0032] [Working principle of single tower mode]

[0033] Adsorption stage: During the industrial production process, the organic waste gas TA is continuously generated and guided to the main exhaust fan 103 through a pipeline. 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 concentration tower 102. In the waste gas concentration tower 102, the organic waste gas TA is in 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, and it has a very large specific surface area. With the help of van der Waals force, 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 concentrated adsorption of the organic waste gas TA.

[0034] Desorption Phase: As the adsorption process continues, the spherical adsorbent BT gradually reaches adsorption saturation. At this point, the controller 101 receives a saturation signal from the spherical adsorbent fluidized bed 104 and immediately initiates a command to activate the main adsorbent conveyor 105. The main adsorbent conveyor 105 transports 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 upper level, the main adsorbent conveyor 105, under the control of the controller 101, stops. The controller 101 then systematically closes all valves connected to the first vacuum thermal desorption tower 106 to ensure the system's tightness. Next, the controller 101 opens the first vacuum valve 109 and simultaneously activates the vacuum pump 112. The vacuum pump 112 begins evacuating the first vacuum thermal desorption tower 106, reducing the pressure within the tower. Simultaneously, the controller 101 controls the first heating valve 107 to open and connect it to the hot gas source HS. High-temperature gas generated by the hot gas source HS enters the first vacuum thermal desorption tower 106, raising the temperature inside the tower to 50-200°C. Under the dual effects of vacuum and heat, the organic waste gas (TA) molecules adsorbed within the micropores of the spherical adsorbent (BT) gain sufficient energy to overcome the adsorption force and desorb from the spherical adsorbent's surface, remaining in the first vacuum thermal desorption tower 106 as a gas.

[0035] Condensation and Recovery Stage: The gaseous organic waste gas TA desorbed from the spherical adsorbent BT enters the first vacuum condenser 111 through the first vacuum valve 109 under the suction force of the vacuum pump 112. When the pressure in the first vacuum thermal desorption tower 106 reaches -10 kPa to -200 kPa and the condensation temperature in the first vacuum condenser 111 reaches -2 to 5 degrees Celsius, the gaseous organic waste gas TA undergoes a phase change upon cooling, condensing into a recovery liquid BL. Under the action of gravity, the recovery liquid BL flows into the first recovery storage tank 113 for storage, thereby recovering the organic waste gas TA.

[0036] Adsorbent Regeneration Phase: When the desorption process is complete, the spherical adsorbent BT within the first vacuum thermal desorption tower 106 regains its adsorption activity. At this point, the controller 101 controls the opening of the first vacuum breaker valve 110, allowing outside air to enter the first vacuum thermal desorption tower 106 and break the vacuum state within the first vacuum thermal desorption tower 106. Subsequently, the controller 101 activates the first adsorbent delivery device 108, which delivers the regenerated spherical adsorbent BT back to the spherical adsorbent fluidized bed 104, allowing it to re-participate in the adsorption process, achieving adsorbent recycling.

[0037] [How the dual tower model works]

[0038] The first tower adsorbs, the second tower desorbs: the main exhaust fan 103 continuously transports the organic waste gas TA to the waste gas concentration tower 102, and performs adsorption purification in the spherical adsorbent fluidized bed 104. At the same time, when the first vacuum thermal desorption tower 106 completes the previous round of thermal desorption operation, 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 conveys the adsorption-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 material 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, introduces high-temperature gas from the hot gas source HS, and raises the temperature in the second vacuum thermal desorption tower 114 to 50-200 degrees Celsius for thermal desorption.

[0039] The first tower desorbs, the second tower adsorbs: When the second vacuum thermal desorption tower 114 completes the thermal desorption operation, the controller 101 closes all 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 adsorption saturated spherical adsorbent BT to the first vacuum thermal desorption tower 106. Repeat the above-mentioned desorption, condensation recovery and adsorbent regeneration process 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.

[0040] [Auxiliary working principle of pressure regulating device]

[0041] 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 within the first vacuum thermal desorption tower 106 and the second vacuum thermal desorption tower 114 in real time and fine-tunes the pressure within the towers according to a preset pressure range. By precisely controlling the pressure within the towers, the adsorption equilibrium of the organic waste gas TA on the spherical adsorbent BT is disrupted, making it easier for the organic waste gas TA molecules to escape from the micropores of the spherical adsorbent BT, further improving desorption efficiency and reducing system energy consumption.

[0042] To go further, in a closed environment, the state when 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 the equilibrium state. The liquid phase in the equilibrium state is called a saturated liquid, and the gas phase is called the saturated vapor pressure. The equilibrium state of a substance is related to factors such as pressure and temperature. When the pressure and temperature change, the equilibrium will be broken. When the pressure, temperature and other parameters stabilize, the equilibrium state is re-established. The equilibrium state corresponds to the temperature and pressure of the substance. However, when desorbing the adsorbent, it often happens that the desorption temperature is higher than the boiling point of the adsorbate (organic waste gas), but the desorption effect is not good. The reason is that inside the adsorbent, due to capillary condensation, the adsorbate produces "chemical adsorption" and a state where a phase change should occur but does not. The chemical adsorption phenomena include: supersaturated vapor, supercooled liquid, superheated liquid, and supersaturated solution.

[0043] The desorption of spherical adsorbent BT requires heating and changing the vacuum degree to effectively change the van der Waals force or chemical adsorption and thus effectively desorb the adsorbent.

[0044] In the present invention, the VOCs attached to the spherical adsorbent BT are continuously adjusted by adjusting the vacuum degree in the first and 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 allowing the VOCs accumulated in the micropores to be desorbed in the shortest time.

[0045] Simply put, the existing technology performs desorption under a stable low-pressure state in the thermal desorption tower. The organic waste gas is attached to the adsorbent in a relatively balanced state, making it difficult for the organic waste gas to escape from the adsorbent micropores, resulting in poor desorption effect. The present invention combines the vacuum pump 112 and the pressure regulating device 119 through the first vacuum condenser 111 to make the pressure in the first vacuum thermal desorption tower 106 or the second vacuum thermal desorption tower 114 in a vacuum state, breaking the relative equilibrium state of VOCs attached to the spherical adsorbent BT, making it easy for the organic waste gas TA to escape from the micropores of the spherical adsorbent BT, resulting in high desorption efficiency and better desorption effect.

[0046] Furthermore, the volatile organic gas vacuum thermal desorption condensation recovery system 100 further includes a second vacuum condenser 120 and a second recovery tank 121. The second recovery tank 121 is connected to the second vacuum condenser 120, which is in turn connected to the vacuum pump 112. The second vacuum condenser 120 and the second recovery tank 121 have the same functions as the first vacuum condenser 111 and the first recovery tank 113, and are not further described here.

[0047] In terms of scalability, the vacuum thermal desorption condensation recovery system for volatile organic gases disclosed in the present invention can be expanded from the aforementioned two vacuum thermal desorption towers to three, four, or even more vacuum thermal desorption towers. The operating mechanisms of more than three towers can be understood by referring to the operating mechanisms of the aforementioned single and dual towers, and will not be repeated here.

[0048] In summary, the vacuum thermal desorption condensation recovery system for volatile organic gases disclosed in the present invention can provide the following benefits:

[0049] 1. High-Efficiency Adsorption Recovery: The system of this invention can efficiently concentrate, adsorb, and condense volatile organic gases (VOCs) even at high air volumes of 12,000 to 150,000 CMH and low-concentration exhaust. The organic waste gas (TA) released from the micropores of the spherical adsorbent (BT) can be concentrated 1,000 to 5,000 times, significantly improving the concentration of the recovered liquid and resource recovery rate.

[0050] 2. Continuous Operation: The system uses two vacuum thermal desorption towers and switches between them to achieve continuous regeneration and recycling of the adsorbent, ensuring continuous adsorption and desorption. This not only improves waste gas treatment efficiency but also minimizes the impact on production.

[0051] 3. Precise control: The controller can precisely control the operating parameters of each device, such as temperature, pressure, flow, etc. Through real-time monitoring and adjustment, it ensures that the system always operates under the optimal working conditions, improving the stability and reliability of exhaust gas treatment.

[0052] 4. Energy saving and consumption reduction: This system uses vacuum thermal desorption technology to reduce the desorption temperature and effectively reduce energy consumption. In addition, the application of the pressure regulating device further improves the desorption efficiency and reduces the operating cost of the system.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, any equivalent changes or modifications based on the features and spirit of the claims of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A vacuum thermal desorption condensation recovery system for volatile organic gases, characterized in that: include: a controller; an exhaust gas concentrating tower connected to and controlled by the controller; a main exhaust fan connected to the controller and controlled by the controller, and connected to the exhaust gas concentration tower, the main exhaust fan being used to transport an organic waste gas to the exhaust gas concentration tower through an airflow, wherein the organic waste gas is volatile organic compounds (VOCs); a spherical adsorbent fluidized bed disposed within the exhaust gas concentration tower, the spherical adsorbent fluidized bed comprising a plurality of spherical adsorbents and configured to concentrate and adsorb the organic waste gas under conditions of a high air volume of 12,000 to 150,000 CMH and low-concentration exhaust gas, wherein the plurality of spherical adsorbents are spherical resins or spherical activated carbons; a main adsorbent delivery device disposed inside the exhaust gas concentration tower, the main adsorbent delivery device being 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 conveying device, the first vacuum thermal desorption tower being used to receive the plurality of saturated spherical adsorbents, wherein the main adsorbent conveying device is used to convey the plurality of saturated spherical adsorbents from the spherical adsorbent fluidized bed to the first vacuum thermal desorption tower; a first heating valve connected to the controller and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first heating valve being connected to a hot gas source, and the hot gas source being used to supply heating; a first adsorbent conveying device connected to and controlled by the controller and connected to the first vacuum thermal desorption tower, the first adsorbent conveying device being used to convey the plurality of spherical adsorbents that have completed desorption in the first vacuum thermal desorption tower to the spherical adsorbent fluidized bed; a first vacuum valve connected to the controller and controlled by the controller, and connected to the first vacuum thermal desorption tower; a first vacuum breaker valve connected to and controlled by the controller, and connected to the first vacuum thermal desorption tower, the first vacuum breaker valve being used to break the vacuum state in 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 a desired vacuum level in the tower; and a first recovery storage tank connected to the first vacuum condenser, wherein 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 in the first vacuum thermal desorption tower reaches -10KPa to -200KPa and the condensation temperature reaches -2 to 5 degrees Celsius during the desorption process of the first vacuum thermal desorption tower; The controller is used to enable the main adsorbent conveying device to convey the multiple saturated spherical adsorbents to the first vacuum thermal desorption tower to a high material level and then stop conveying. The controller then closes all valves corresponding to the first vacuum thermal desorption tower and simultaneously opens the first vacuum valve and the vacuum pump to perform air extraction. At the same time, the hot air source is supplied through the first heating valve and heated to 50-200 degrees Celsius for desorption. When the vacuum pump is exhausting air, it reaches -10KPa to -200KPa through the first vacuum condenser and the condensation temperature is between -2 and 5 degrees Celsius. The organic waste gas begins to condense into the recovery liquid and is discharged into the first recovery storage tank.

2. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 1, characterized in that: The first vacuum thermal desorption tower after desorption is broken into a vacuum state through the first vacuum breaking valve, and the controller then transports the plurality of spherical adsorbents after desorption to the spherical adsorbent fluidized bed through the first adsorbent transporting device for re-adsorption.

3. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 2, characterized in that: Also includes: a second vacuum thermal desorption tower connected to and controlled by the controller and connected to the main adsorbent conveying device, the second vacuum thermal desorption tower being used to receive the plurality of saturated spherical adsorbents, wherein the main adsorbent conveying device is used to convey the plurality of saturated spherical adsorbents from the spherical adsorbent fluidized bed to the second vacuum thermal desorption tower; a second heating valve connected to the controller and controlled by the controller, and connected to the second vacuum thermal desorption tower, the second heating valve being connected to the hot gas source and used to supply heating; a second adsorbent conveying device connected to and controlled by the controller, the second adsorbent conveying device being used to convey the plurality of spherical adsorbents desorbed 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; and A second vacuum breaking valve is connected to the controller and controlled by the controller, and is connected to the second vacuum thermal desorption tower. The second vacuum breaking valve is used to break the vacuum state in the second vacuum thermal desorption tower. After the first vacuum thermal desorption tower completes the thermal desorption operation, the corresponding valve will be closed. Then, the controller is used to enable the main adsorbent conveying device to convey the multiple saturated spherical adsorbents to the second vacuum thermal desorption tower to the high material level and then stop conveying. Then, the controller is used to close all valves corresponding to the second vacuum thermal desorption tower and open the second vacuum valve at the same time. The vacuum pump is used to evacuate air, and the hot air source is supplied through the second heating valve and heated to 50-200 degrees Celsius for desorption. When the vacuum pump is evacuating air, when the temperature reaches -10KPa to 200KPa through the first vacuum condenser and the condensation temperature is between -2 and 5 degrees Celsius, the organic waste gas begins to condense into the recovery liquid and is discharged into the first recovery storage tank.

4. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 3, characterized in that: The second vacuum thermal desorption tower after desorption is broken into a vacuum state through the second vacuum breaking valve, and the controller then transports the plurality of spherical adsorbents after desorption to the spherical adsorbent fluidized bed through the second adsorbent transporting device for re-adsorption.

5. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 4, characterized in that: The multiple spherical adsorbents that have been saturated with adsorption are subjected to thermal desorption in the first vacuum thermal desorption tower or the second vacuum thermal desorption tower. The desorbed multiple spherical adsorbents are then 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. In this way, switching and circulation are carried out between the two towers to achieve continuous adsorption and desorption, emission compliance and recovery of the organic waste gas.

6. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 3, characterized in that: Also includes: A pressure regulating device is connected to the first vacuum condenser. The pressure regulating device is used to cooperate with the vacuum pump to adjust the vacuum degree in the first vacuum thermal desorption tower and the second vacuum thermal desorption tower and change the internal pressure to break the phase equilibrium of the organic waste gas attached to the multiple spherical adsorbents, further making it easier for the organic waste gas to be separated from the micropores of the multiple spherical adsorbents.

7. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 1, characterized in that: The particle size of the spherical adsorbent is 0.3 mm to 2 mm.

8. The vacuum thermal desorption condensation recovery system for volatile organic gases according to claim 1, characterized in that: The organic waste gas is separated from the micropores of the plurality of spherical adsorbents and concentrated by a factor of 1,000 to 5,000.

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