A waste gas VOC recovery device and recovery process

Abstract

The application discloses a kind of VOC recovery equipment and recovery process in waste gas, it is related to waste gas recovery technical field, including: conical bottom tank, float, guide pipe and drain pipe.The application further discloses a kind of recovery process of VOC recovery equipment in waste gas, including the following steps: waste gas collection and pretreatment, condensation recovery, transition deposition and product output.The application is by installing float for separating space in the inside of conical bottom tank, float floats on the surface of VOC liquid phase, reduce the contact area of VOC liquid phase and air, so as to reduce the dispersion of liquid VOC, so as to reduce the loss of VOC in transition standing process, by using the mode of magnetic coupling driving to realize the up and down adjustment of float, in the process of VOC liquid phase in and out material, can actively adjust float position, to reduce the pressure change generated in conical bottom tank inside due to VOC liquid phase in and out material, so as to further reduce the dispersion of VOC, so that the purity of liquid phase VOC finally output by device is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of waste gas recovery technology, and in particular to a VOC recovery device and process for waste gas. Background Technology

[0002] The recovery and resource utilization of volatile organic compounds (VOCs) is a key link for industries such as chemical, coating, and printing to achieve environmental compliance and reduce costs and increase efficiency. A typical recovery process usually includes steps such as "adsorption concentration - desorption regeneration - condensation liquefaction - solvent purification". Among them, the condensed liquid VOC mixture needs to be temporarily stored, buffered and initially separated into oil and water in a transition tank before entering the distillation column for purification.

[0003] Currently, the industry generally uses fixed-roof tanks or simple floating-roof tanks as transitional storage tanks. However, the pressure balance inside existing storage tanks is difficult to control precisely. When a large amount of room temperature or low temperature liquid suddenly enters during feeding, it may cause drastic pressure fluctuations inside the tank, resulting in the unorganized release of VOCs. When discharging, the rapid discharge of materials causes pressure imbalance inside the storage tank, which will also cause the unorganized release of VOCs. Moreover, the discharge process can easily disturb the sediment layer, affecting the feed quality and operational stability of subsequent distillation units.

[0004] Therefore, it is necessary to invent a VOC recovery device and process for waste gas to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide a VOC recovery device and process for waste gas to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a VOC recovery device for waste gas, comprising:

[0007] A conical-bottomed tank, wherein a conical bottom is provided at the bottom end, and a tank lid is fixedly installed at the top end of the conical-bottomed tank;

[0008] A floating plate is installed inside a conical bottom tank that can slide up and down. Multiple floats are fixedly installed on the lower surface of the floating plate, and multiple breather valves are installed through the middle of the floating plate. The floating plate divides the inside of the conical bottom tank into two spaces: the space above the floating plate is used for the replacement of gaseous VOCs with nitrogen, and the space below the floating plate is used for the sedimentation and discharge of liquid VOCs.

[0009] The feed pipe has two pipes that both penetrate the middle of the floating plate. The two feed pipes are used for feeding and discharging liquid VOCs, respectively. The bottom of the feed pipe is lower than the discharge pipe. The top of each feed pipe is fitted with a fixing pipe, and both fixing pipes penetrate the tank cover.

[0010] A drain pipe is fixedly installed at the bottom of the cone. An annular filter screen is fixedly installed inside the drain pipe, and a drain valve is installed through the outside of the drain pipe.

[0011] Preferably, it also includes a guide tube, which is fixedly installed in the middle of the lower surface of the can lid and located inside the conical bottom can;

[0012] A guide sleeve, which penetrates the middle of the floating roof and is fitted onto the outside of the guide tube, has multiple coupling magnetic plates installed around its inner sidewall.

[0013] A lead screw sleeve is slidably installed inside a guide tube. A transmission lead screw is installed through the inside of the lead screw sleeve and is rotatably installed inside the guide tube. A transmission seat is installed at the bottom end of the lead screw sleeve. Multiple coupling magnetic blocks are installed around the outer wall of the transmission seat. The multiple coupling magnetic blocks and multiple coupling magnetic plates achieve transmission connection between the lead screw sleeve and the guide sleeve through magnetic coupling. The lead screw sleeve drives the floating plate to move up and down through the guide sleeve.

[0014] Preferably, it also includes a pressure sensor, which is fixedly installed between the lead screw sleeve and the transmission seat. The pressure sensor is used to detect the stress change of the transmission seat when the coupling magnetic block and the coupling magnetic plate are magnetically coupled, so as to determine the connection status between the float and the lead screw sleeve.

[0015] Preferably, it also includes a lead screw motor, which is fixedly installed on the upper surface of the can lid and its output shaft is connected to the top end of the transmission lead screw. The lead screw motor is used to provide power to the transmission lead screw, and the cross-section of the guide tube and the lead screw sleeve are both "S" shaped structures.

[0016] Preferably, polytetrafluoroethylene sealing rings are fixedly installed on the middle part of the outer side wall of the floating table and at both ends of the inner side wall of the guide sleeve.

[0017] Preferably, an anti-sticking mesh is fixedly installed on the lower surface of the floating disk. The anti-sticking mesh is used to reduce the stress between the floating disk and the VOC solution surface to facilitate the upward movement of the floating disk.

[0018] Preferably, it also includes an air guide hood, which is fixedly installed on the top of the breathing valve and has an inclined structure on its upper surface. An air outlet groove is provided through one end of the upper surface of the air guide hood.

[0019] A support frame is fixedly installed inside the breather valve. A support rod is installed through the middle of the support frame. A sealing plate is fixedly installed at the top of the support rod, and the lower surface of the sealing plate is in contact with the upper surface of the support frame. A support block is fixedly installed at the bottom of the support rod, and a top spring is installed between the support block and the support frame. The support frame, support rod, and sealing plate form a one-way sealing structure to restrict the backflow of gaseous VOCs in the space above the floating plate into the liquid VOCs.

[0020] Preferably, it also includes anti-vortex shrouds, which are provided in two and fixedly installed at the bottom of the two guide tubes respectively, and the interior of the two anti-vortex shrouds is provided with multiple inclined through grooves.

[0021] Preferably, it also includes a nitrogen purging valve, which is installed through the upper surface of the tank cover, and the nitrogen purging valve is used to inject nitrogen into the interior of the conical bottom tank;

[0022] The access port is installed through the upper surface of the tank cover;

[0023] A slag discharge pipe is fixedly installed at the bottom end of a drain pipe and is used to discharge the sedimented waste slag inside the conical bottom tank.

[0024] A VOC recovery process for waste gas includes the following steps:

[0025] Step 1: Waste gas collection and pretreatment. The mixed gas containing VOCs generated from each production point is collected through pipelines, filtered for dust removal, condensed for dehumidification, and concentrated to form high-concentration VOC gas.

[0026] Step 2: Condensation and recovery. The high-concentration VOC gas formed in Step 1 is condensed by a condenser unit to form liquid VOC.

[0027] Step 3: Transitional sedimentation. The liquid VOC obtained in Step 2 is injected into the space below the floating plate inside the conical bottom tank through the feed pipe. During the injection process, some gaseous VOCs will volatilize due to temperature changes. The gaseous VOCs move through the breather valve in the middle of the floating plate to the space above the floating plate. During this process, nitrogen is injected into the space above the floating plate inside the conical bottom tank through the nitrogen replacement valve to replace and collect the volatilized gaseous VOCs. The liquid VOCs below the floating plate complete automatic stratification, with the upper layer being a pure VOC liquid phase, the middle layer being a pure water phase, and the lower layer being impurities and polymer waste residue.

[0028] Step 4: Product output. The pure VOC liquid phase from the upper layer in Step 3 is extracted through the feed pipe and transported to the distillation column for separation and purification to obtain pure VOC solvent.

[0029] The technical effects and advantages of this invention are as follows:

[0030] 1. This invention installs a floating plate inside the conical bottom tank to separate the space. The floating plate floats on the surface of the VOC liquid phase, reducing the contact area between the VOC liquid phase and the air, thereby reducing the escape of liquid VOC and reducing VOC loss during the transition and settling process. The floating plate is adjusted up and down by using magnetic coupling drive. The position of the floating plate can be actively adjusted during the VOC liquid phase feeding and discharging process to reduce the pressure changes inside the conical bottom tank caused by the feeding and discharging of VOC liquid phase, thereby further reducing the escape of VOC and ensuring the purity of the liquid VOC output by the device.

[0031] 2. This invention uses a conical bottom structure as the liquid-phase VOC precipitation and separation zone. The conical structure design ensures that the higher proportion of liquid-phase VOCs can better converge at the top. Furthermore, by using inlet and outlet designs at different heights, the liquid-phase VOCs enter the conical bottom tank from a lower position, thereby reducing disturbance to the upper pure liquid-phase VOCs. This achieves a material circulation path of horizontal flow entry and laminar flow extraction, effectively ensuring the purity of the liquid-phase VOCs output by the device. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0033] Figure 2 This is a cross-sectional view of the overall structure of the present invention.

[0034] Figure 3 This is a schematic diagram of the can lid structure of the present invention.

[0035] Figure 4 This is a schematic diagram of the floating roof structure of the present invention. Figure 1 .

[0036] Figure 5 This is a schematic diagram of the floating roof structure of the present invention. Figure 2 .

[0037] Figure 6 This is a schematic diagram of the lead screw sleeve structure of the present invention.

[0038] Figure 7 This is a schematic diagram of the internal structure of the anti-vortex shield of the present invention.

[0039] Figure 8 This is a cross-sectional schematic diagram of the breather valve structure of the present invention.

[0040] Figure 9 This is a cross-sectional schematic diagram of the drainage pipe structure of the present invention.

[0041] Figure 10 This is a schematic diagram of the internal liquid phase stratification of the conical bottom tank structure of the present invention.

[0042] In the diagram: 1. Conical bottom tank; 11. Conical bottom; 12. Tank cover; 13. Nitrogen replacement valve; 14. Inspection port; 121. Guide pipe; 2. Float; 21. Float ball; 22. Breathing valve; 23. Guide sleeve; 24. Screw sleeve; 25. Anti-sticking mesh; 231. Coupling magnetic plate; 241. Transmission screw; 2411. Screw motor; 242. Transmission seat; 243. Coupling magnetic block; 244. Pressure sensor; 221. Gas guide hood; 222. Support frame; 223. Support rod; 224. Sealing plate; 225. Support block; 3. Material guide pipe; 31. Fixed pipe; 32. Anti-vortex hood; 33. Through groove; 4. Drain pipe; 41. Annular filter screen; 42. Drain valve; 43. Slag discharge pipe. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figures 1 to 10 As shown, the VOC recovery device in waste gas provided by the present invention is essentially a transition tank for liquid phase transition and stratification during the VOC recovery process.

[0045] In terms of specific structural installation, the structural body can be constructed according to the inventive concept of this embodiment. In this embodiment, no special limitations are imposed.

[0046] In this embodiment, a VOC recovery device for waste gas includes:

[0047] The conical bottom tank 1 has a conical bottom 11 at its bottom end and a tank cover 12 fixedly installed at the top end of the conical bottom tank 1. The main body of the conical bottom tank 1 is a three-dimensional cylinder, and the bottom end is smoothly connected to the conical bottom 11. The overall material is stainless steel, and the interior is lined with a corrosion-resistant carbon steel lining. The tank cover 12 is connected to the conical bottom tank 1 by a flange.

[0048] Nitrogen replacement valve 13 is installed through the upper surface of tank cover 12. Nitrogen replacement valve 13 is used to inject nitrogen into the interior of conical bottom tank 1. Nitrogen replacement valve 13 is a pilot-operated regulating valve. A nitrogen pipeline is connected in front of the valve for injecting nitrogen. A one-way exhaust valve is provided on the side of the valve for one-way exhaust from the tank.

[0049] Inspection port 14 is installed through the upper surface of tank cover 12;

[0050] The floating plate 2 is installed inside the conical bottom tank 1 and can slide up and down. Multiple floats 21 are fixedly installed on the lower surface of the floating plate 2, and multiple breather valves 22 are installed through the middle of the floating plate 2. The floating plate 2 divides the interior of the conical bottom tank 1 into two spaces, upper and lower. The space above the floating plate 2 is used for the replacement of gaseous VOCs with nitrogen, and the space below the floating plate 2 is used for the sedimentation and discharge of liquid VOCs.

[0051] The guide tube 121 is fixedly installed in the middle of the lower surface of the can cover 12 and located inside the conical bottom can 1;

[0052] The guide sleeve 23 passes through the middle of the floating roof 2 and is sleeved on the outside of the guide tube 121. Polytetrafluoroethylene sealing rings are fixedly installed on the middle of the outer side wall of the floating roof 2 and both ends of the inner side wall of the guide sleeve 23.

[0053] The lead screw sleeve 24 is slidably installed inside the guide tube 121. A transmission lead screw 241 is installed through the inside of the lead screw sleeve 24 and is rotatably installed inside the guide tube 121. A transmission seat 242 is installed at the bottom end of the lead screw sleeve 24. Multiple coupling magnetic blocks 243 are installed around the outer side wall of the transmission seat 242. Multiple coupling magnetic plates 231 are installed around the inner side wall of the guide sleeve 23. The multiple coupling magnetic blocks 243 and the multiple coupling magnetic plates 231 achieve transmission connection between the lead screw sleeve 24 and the guide sleeve 23 through magnetic coupling. The lead screw sleeve 24 drives the floating disk 2 to move up and down through the guide sleeve 23.

[0054] The lead screw motor 2411 is fixedly installed on the upper surface of the can cover 12 and its output shaft is connected to the top of the transmission lead screw 241. The lead screw motor 2411 is used to provide power to the transmission lead screw 241. The cross-section of the guide tube 121 and the lead screw sleeve 24 are both "S" shaped structures. The "S" shaped structure ensures that the lead screw sleeve 24 can only slide axially and cannot rotate, so as to ensure that the transmission lead screw 241 can stably drive the lead screw sleeve 24 to rise and fall.

[0055] Pressure sensor 244 is fixedly installed between lead screw sleeve 24 and transmission seat 242. Pressure sensor 244 is used to detect the stress change of transmission seat 242 when the coupling magnetic block 243 and the coupling magnetic plate 231 are magnetically coupled to determine the connection state between float 2 and lead screw sleeve 24. Pressure sensor 244 is a miniature strain gauge sensor, which is embedded in the force path of transmission seat 242. When magnetic coupling transmission occurs, the transmission seat is subjected to a reverse force. The sensor monitors this axial stress value to determine the coupling state between float 2 and lead screw sleeve 24.

[0056] An anti-sticking mesh 25 is fixedly installed on the lower surface of the floating disk 2. The anti-sticking mesh 25 is used to reduce the stress between the floating disk 2 and the VOC solution surface so that the floating disk 2 can move upward.

[0057] The gas guide hood 221 is fixedly installed on the top of the breathing valve 22 and its upper surface is designed with an inclined structure. One end of the upper surface of the gas guide hood 221 is provided with an outlet groove. The inclined structure of the upper surface causes the gas phase VOC to move obliquely after passing through the gas guide hood 221 and being discharged. This allows the gas phase VOC discharged from multiple gas guide hoods 221 to enter the nitrogen environment in multiple directions, ensuring that the nitrogen and gas phase VOC are mixed quickly to dilute the gas phase VOC and reduce the risk of excessive gas phase VOC concentration affecting the environment inside the tank.

[0058] The support frame 222 is fixedly installed inside the breather valve 22. A support rod 223 is installed through the middle of the support frame 222. A sealing plate 224 is fixedly installed at the top of the support rod 223, and the lower surface of the sealing plate 224 is in contact with the upper surface of the support frame 222. A support block 225 is fixedly installed at the bottom of the support rod 223, and a top spring is installed between the support block 225 and the support frame 222. The support frame 222, the support rod 223 and the sealing plate 224 form a one-way sealing structure to restrict the backflow of gaseous VOCs in the space above the floating disk 2 into the liquid VOCs.

[0059] The feed pipe 3 has two pipes that both penetrate the middle of the floating plate 2. The two feed pipes 3 are used for feeding and discharging liquid VOCs respectively. The bottom of the feed pipe 3 is lower than the discharge pipe 3. The top of each feed pipe 3 is fitted with a fixed pipe 31, and both fixed pipes 31 penetrate the tank cover 12. The staggered design of the two feed pipes 3 achieves the effect of "high inlet and low outlet", realizing the feed and discharge mode of horizontal flow and laminar flow liquid extraction, minimizing the disturbance to the sedimentation layer.

[0060] Two anti-vortex hoods 32 are provided and fixedly installed at the bottom of the two feed pipes 3 respectively. The interior of the two anti-vortex hoods 32 is provided with multiple inclined through grooves 33. The anti-vortex hoods 32 with inclined through grooves 33 can convert the axial suction force into radial diffusion flow, effectively eliminate suction vortices, prevent the bottom sediment from being rolled up, and ensure the purity of the output liquid phase.

[0061] Drain pipe 4 is fixedly installed at the bottom end of cone bottom 11. An annular filter screen 41 is fixedly installed inside drain pipe 4, and a drain valve 42 is installed through the outside of drain pipe 4.

[0062] The slag discharge pipe 43 is fixedly installed at the bottom end of the drain pipe 4. The slag discharge pipe 43 is used to discharge the sedimented waste slag inside the conical bottom tank 1.

[0063] When using the VOC recovery device in the exhaust gas according to this embodiment, when the device is put into use, firstly control the floating plate 2 to be lowered to the bottom of the cone bottom tank 1, and inject nitrogen into the space above the floating plate 2 inside the cone bottom tank 1 through the nitrogen replacement valve 13. During the injection process, the nitrogen replaces the air inside the cone bottom tank 1 (the nitrogen replacement valve 13 is used in combination with the one-way valve. After the nitrogen is injected into the cone bottom tank 1, the air pressure inside the cone bottom tank 1 rises, causing the one-way valve to open. The original air inside the cone bottom tank 1 is discharged through the one-way valve to complete the replacement of air by nitrogen). After the nitrogen is injected into the cone bottom tank 1, a nitrogen environment is formed inside the cone bottom tank 1. During this process, the lead screw sleeve 24 is located at the bottom end of the transmission lead screw 241. The lead screw sleeve 24 and the floating plate 2 are in a misaligned and separated state. The floating plate 2 is located at the connection between the cone bottom tank 1 and the cone bottom 11.

[0064] After the equipment completes the initial preparation, the pre-treated liquid VOC is injected into the area below the floating plate 2 in the conical bottom tank 1 through the feed pipe 3. As the liquid VOC is injected, the floating plate 2 moves upward with the change of liquid level. During the liquid VOC feeding process, some gaseous VOC evaporates due to temperature and pressure changes, which increases the air pressure between the lower surface of the floating plate 2 and the liquid surface. Under the action of air pressure, this part of gaseous VOC opens the breather valve 22 and passes through the breather valve 22 to reach the nitrogen environment above the floating plate 2, and is then diluted by nitrogen.

[0065] After feeding stops, the floating disk 2 is in close contact with the liquid VOC surface under the buoyancy provided by the float ball 21, so as to reduce the contact area between the liquid VOC and the air, thereby suppressing the escape of gaseous VOC. During this process, the anti-sticking mesh 25 on the lower surface of the floating disk 2 breaks the balance of the liquid surface and prevents the floating disk 2 from adhering to the liquid surface.

[0066] During the process between feeding and discharging, the liquid VOC settles under the action of gravity, forming a three-layer structure with a pure VOC liquid phase on the top, a pure water phase in the middle, and impurities and polymer waste in the bottom.

[0067] After the equipment has been left to stand for a certain period of time and the liquid phase VOCs have been separated, it can enter the discharge process. The upper pure VOC liquid phase is pumped out through the discharge guide pipe 3. Since the position of the discharge guide pipe 3 is limited by the floating plate 2 and is always on the upper layer of the mixed liquid phase, the discharge guide pipe 3 can directly pump out the pure VOC liquid phase. During the pumping process, the floating plate 2 remains in contact with the liquid surface of the mixed liquid phase to ensure the pressure balance of the mixed liquid phase, thereby reducing the emission of gaseous VOCs during the discharge process.

[0068] After the initial feeding and discharging, the equipment enters a transition state, at which point intermittent feeding and discharging of liquid VOCs can be achieved. During the intermittent feeding process, the lead screw sleeve 24 is controlled to move upward until it reaches a position flush with the guide sleeve 23 in the middle of the floating plate 2 (when the lead screw sleeve 24 reaches its position, the coupling magnetic plate 231 and the coupling magnetic block 243 are magnetically coupled, and the force generated by the magnetic coupling is converted into the force between the lead screw sleeve 24 and the transmission seat 242, which is detected by the pressure sensor 244. By detecting the change in the reading of the pressure sensor 244, it can be determined whether the lead screw sleeve 24 and the floating plate 2 have completed magnetic coupling). After the lead screw sleeve 24 completes magnetic coupling with the floating plate 2, it drives the floating plate 2 to move upward slightly, so that the floating plate 2 is separated from the liquid VOCs. At this time, a small gas phase space is formed between the floating plate 2 and the liquid VOCs, providing a buffer space for the liquid VOCs that are about to enter and the gas phase VOCs that have volatilized due to the feeding effect.

[0069] After feeding is completed, the control screw sleeve 24 moves downward, and the float 2 moves downward together. The float 2 compresses the gas phase space downward, so that the gas phase VOC is compressed and passes through the breather valve 22 into the nitrogen environment above the float 2. After the gas phase VOC is transferred, the float 2 is in contact with the liquid surface. At this time, the screw sleeve 24 continues to move upward, while the float 2 stops moving due to the obstruction of the liquid phase. The resistance experienced by the float 2 is greater than the magnetic force of the magnetic coupling, so that the magnetic coupling between the screw sleeve 24 and the float 2 is separated. At this time, the float 2 is only affected by the liquid phase and moves with the liquid surface.

[0070] After the equipment has been running for a certain period of time, pure water and waste residue are discharged (this time is affected by the purity of the liquid VOC raw material and can be flexibly adjusted according to the actual operating conditions). The drain valve 42 is opened, and the water phase of the pure water layer at the bottom of the cone 11 passes through the annular filter screen 41 and is discharged through the drain valve 42. The valve between the slag discharge pipe 43 and the drain pipe 4 is opened, and the solid waste residue is discharged through the slag discharge pipe 43. During the entire waste discharge process, the floating plate 2 always isolates the upper and lower spaces to prevent nitrogen from being discharged together and damaging the inert gas protective environment inside the tank.

[0071] This invention also provides a VOC recovery process for a waste gas VOC recovery device, comprising the following steps:

[0072] Step 1: Waste gas collection and pretreatment. The mixed gas containing VOCs generated from each production point is collected through pipelines, filtered for dust removal, condensed for dehumidification, and concentrated to form high-concentration VOC gas.

[0073] Among them, filtration and dust removal are carried out using bag filters or cartridge filters to remove particles with a diameter >1μm from the mixed gas and prevent clogging of subsequent processing equipment; condensation and dehumidification are carried out by a refrigeration dehumidifier to remove water vapor from the mixed gas; and concentration is carried out by a rotary drum.

[0074] Step 2: Condensation and recovery. The high-concentration VOC gas formed in Step 1 is condensed by a condenser unit to form liquid VOC.

[0075] After condensation, the liquid VOC is discharged through a gas-liquid separator to remove the residual gas VOC. The gas VOC is then returned to step one for further treatment via pipeline.

[0076] Step 3: Transitional sedimentation. The liquid VOC obtained in Step 2 is injected into the space below the floating plate 2 inside the conical bottom tank 1 through the feed pipe 3. During the injection process, some gaseous VOCs will volatilize due to temperature changes. The gaseous VOCs move through the breather valve 22 in the middle of the floating plate 2 to the space above the floating plate 2. During this process, nitrogen is injected into the space above the floating plate 2 inside the conical bottom tank 1 through the nitrogen replacement valve 13 to replace and collect the volatilized gaseous VOCs. The liquid VOCs below the floating plate 2 complete automatic stratification, with the upper layer being a pure VOC liquid phase, the middle layer being a pure water phase, and the lower layer being impurities and polymer waste residue.

[0077] Step 4: Product output. The pure VOC liquid phase from the upper layer in Step 3 is extracted through feed pipe 3 and transported to a distillation column for separation and purification to obtain pure VOC solvent.

[0078] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A VOC recovery device for waste gas, characterized in that, include: A conical bottom tank (1) has a conical bottom (11) at its bottom end, and a tank lid (12) is fixedly installed at the top of the conical bottom tank (1). A floating plate (2) is installed inside the conical bottom tank (1) and can slide up and down. Multiple floats (21) are fixedly installed on the lower surface of the floating plate (2). Multiple breather valves (22) are installed through the middle of the floating plate (2). The floating plate (2) divides the interior of the conical bottom tank (1) into two spaces, upper and lower. The space above the floating plate (2) is used for the replacement of gaseous VOCs with nitrogen, and the space below the floating plate (2) is used for the precipitation and discharge of liquid VOCs. The feed pipe (3) has two pipes that both penetrate the middle of the floating plate (2). The two feed pipes (3) are used for feeding and discharging liquid VOCs respectively. The bottom of the feed pipe (3) is lower than the discharge pipe (3). The top of the two feed pipes (3) is fitted with a fixing pipe (31), and the two fixing pipes (31) both penetrate the tank cover (12). A drain pipe (4) is fixedly installed at the bottom end of the cone bottom (11). An annular filter screen (41) is fixedly installed inside the drain pipe (4), and a drain valve (42) is installed through the outside of the drain pipe (4). The guide tube (121) is fixedly installed in the middle of the lower surface of the can cover (12) and located inside the conical bottom can (1); The guide sleeve (23) passes through the middle of the floating disk (2) and is sleeved on the outside of the guide tube (121). Multiple coupling magnetic plates (231) are installed around the inner sidewall of the guide sleeve (23). A lead screw sleeve (24) is slidably installed inside the guide tube (121). A transmission lead screw (241) is installed through the inside of the lead screw sleeve (24), and the transmission lead screw (241) is rotatably installed inside the guide tube (121). A transmission seat (242) is installed at the bottom end of the lead screw sleeve (24). Multiple coupling magnetic blocks (243) are installed around the outer wall of the transmission seat (242). The multiple coupling magnetic blocks (243) and multiple coupling magnetic plates (231) are magnetically coupled to realize the transmission connection between the lead screw sleeve (24) and the guide sleeve (23). The lead screw sleeve (24) drives the floating plate (2) to move up and down through the guide sleeve (23). Also includes: The lead screw motor (2411) is fixedly installed on the upper surface of the can lid (12) and its output shaft is connected to the top of the transmission lead screw (241). The lead screw motor (2411) is used to provide power to the transmission lead screw (241). The cross-section of the guide tube (121) and the lead screw sleeve (24) are both "Shen" shaped structures.

2. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: A pressure sensor (244) is fixedly installed between the lead screw sleeve (24) and the transmission seat (242). The pressure sensor (244) is used to detect the stress change of the transmission seat (242) when the coupling magnetic block (243) and the coupling magnetic plate (231) are magnetically coupled, so as to determine the connection status between the float (2) and the lead screw sleeve (24).

3. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: Polytetrafluoroethylene sealing rings are fixedly installed on the middle part of the outer side wall of the floating roof (2) and at both ends of the inner side wall of the guide sleeve (23).

4. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: The lower surface of the floating disk (2) is fixedly equipped with an anti-sticking mesh (25), which is used to reduce the stress between the floating disk (2) and the VOC solution surface so that the floating disk (2) can move upward.

5. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: An air guide hood (221) is fixedly installed on the top of the breathing valve (22) and its upper surface is set as an inclined structure. An air outlet groove is provided through one end of the upper surface of the air guide hood (221). A support frame (222) is fixedly installed inside the breathing valve (22). A support rod (223) is installed through the middle of the support frame (222). A sealing plate (224) is fixedly installed at the top of the support rod (223), and the lower surface of the sealing plate (224) is in contact with the upper surface of the support frame (222). A support block (225) is fixedly installed at the bottom of the support rod (223), and a top spring is installed between the support block (225) and the support frame (222). The support frame (222), the support rod (223), and the sealing plate (224) form a one-way sealing structure to restrict the backflow of gaseous VOCs into liquid VOCs in the space above the floating plate (2).

6. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: Two anti-vortex covers (32) are provided and fixedly installed at the bottom of two guide tubes (3). The interior of each of the two anti-vortex covers (32) is provided with multiple inclined through slots (33).

7. The VOC recovery device in waste gas according to claim 1, characterized in that, Also includes: A nitrogen purging valve (13) is installed through the upper surface of the tank cover (12) and is used to inject nitrogen into the interior of the conical bottom tank (1). Inspection port (14), which is installed through the upper surface of the tank cover (12); The slag discharge pipe (43) is fixedly installed at the bottom end of the drain pipe (4) and is used to discharge the sedimented waste slag inside the cone bottom tank (1).

8. A VOC recovery process for a waste gas VOC recovery device, applied to a waste gas VOC recovery device according to any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Waste gas collection and pretreatment. The mixed gas containing VOCs generated from each production point is collected through pipelines, filtered for dust removal, condensed for dehumidification, and concentrated to form high-concentration VOC gas. Step 2: Condensation and recovery. The high-concentration VOC gas formed in Step 1 is condensed by a condenser unit to form liquid VOC. Step 3, transition sedimentation: The liquid VOC obtained in step 2 is injected into the space below the floating plate (2) inside the conical bottom tank (1) through the feed pipe (3). During the injection process, some gaseous VOCs are volatilized due to temperature changes. The gaseous VOCs move through the breathing valve (22) in the middle of the floating plate (2) to the space above the floating plate (2). During this process, nitrogen is injected into the space above the floating plate (2) inside the conical bottom tank (1) through the nitrogen replacement valve (13) to replace and collect the volatilized gaseous VOCs. The liquid VOCs below the floating plate (2) are automatically separated into layers, with the upper layer being the pure VOC liquid phase, the middle layer being the pure water phase, and the lower layer being impurities and polymer waste. Step 4: Product output. The pure VOC liquid phase from the upper layer in Step 3 is extracted through the feed pipe (3) and transported to the distillation column for separation and purification to obtain pure VOC solvent.

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