A VOCs tail gas recovery process and device with pressurized desorption

Abstract

The present invention belongs to the field of VOCs tail gas treatment, in particular to a VOCs tail gas recovery process and device with pressurized desorption; the present invention comprises the following steps: step 1, the VOCs tail gas in the workshop is filtered through a pretreatment device to filter out dust, fiber and other particulate matter in the tail gas; step 2, the VOCs tail gas passes through an air distributor, an activated carbon adsorption component and a catcher in an adsorption tower from bottom to top; step 3, the activated carbon adsorbed with VOCs components in the adsorption tower is transported to a graphene desorption tower for desorption; at the same time, the activated carbon that has been desorbed in the graphene desorption tower is transported to the adsorption tower for reuse; step 4, the VOCs gas is desorbed from the activated carbon; step 5, the high-concentration VOCs tail gas after desorption is introduced into a deep cooling device for cooling, and the VOCs tail gas is condensed from a gaseous state into a liquid solvent; the present invention is provided with an adsorption tower and a graphene desorption tower, which are used for adsorption and desorption of activated carbon respectively, thereby saving the desorption time of the adsorption tower and improving the treatment efficiency of the VOCs tail gas.

Description

Technical Field

[0001] The present invention relates to the technical field of VOCs tail gas treatment, and in particular to a VOCs tail gas recovery process and device with pressurized desorption. Background Art

[0002] VOCs waste gas is a common industrial waste gas in the chemical industry. It has a complex composition and contains a large amount of organic matter such as hydrocarbons, aldehydes, chlorinated hydrocarbons, etc. Most of the components are carcinogenic pollutants. If it is discharged into the atmosphere without treatment, it will seriously endanger human health and cause great harm to the environment. Therefore, the requirements for VOCs tail gas treatment technology are becoming increasingly higher, and it is necessary to efficiently complete tail gas treatment with limited equipment.

[0003] At present, VOCs tail gas is treated by adsorption using activated carbon adsorption towers. The exhaust gas passes through the activated carbon adsorption layer (granular carbon or honeycomb carbon), and the organic molecules are physically adsorbed or chemically adsorbed by the micropores on the surface of the activated carbon. The purified gas is discharged through the chimney after testing and meets the standards. The VOCs component removal efficiency can reach 80%-95%; the existing adsorption tower includes an adsorption stage and a desorption stage. When the activated carbon is saturated, the adsorption tower enters the desorption stage to desorb the VOCs gas adsorbed by the activated carbon. During the desorption process, the adsorption tower cannot perform adsorption work, which affects the tail gas treatment efficiency of the adsorption tower. Secondly, when the adsorption tower switches from the adsorption stage to the desorption stage, the temperature and pressure change greatly. However, the adsorption tower is large in size, heats up slowly, and is difficult to evacuate, resulting in a long desorption time and a relatively general desorption effect. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a pressurized desorption VOCs tail gas recovery process and device. By providing an adsorption tower and a graphene desorption tower, activated carbon can be transported, ensuring that the adsorption tower can always work, aiming to solve the problems in the background technology.

[0005] In order to achieve the above technical objectives, the specific technical solutions of the present invention are as follows: a VOCs tail gas recovery process by pressurized desorption proposed by the present invention comprises the following steps:

[0006] Step 1: The VOCs exhaust gas from the workshop is filtered through pre-treatment equipment to remove dust, fiber and other particulate matter, and then introduced into the adsorption tower through a high-pressure centrifugal fan;

[0007] Step 2: The VOCs exhaust gas passes through the air distributor, activated carbon adsorption component and capture device from bottom to top in the adsorption tower. The VOCs components in the exhaust gas are fully adsorbed by the activated carbon. After meeting the standards, the exhaust gas is discharged from the chimney;

[0008] Step 3: The activated carbon adsorbed with VOCs in the adsorption tower is transported to the graphene desorption tower for desorption; at the same time, the activated carbon that has been desorbed in the graphene desorption tower is transported to the adsorption tower for reuse;

[0009] Step 4: A heat medium is introduced into the graphene desorption tower to heat the activated carbon. At the same time, the graphene desorption tower is evacuated to a vacuum state by a vacuum pump. As the vacuum degree and temperature in the tower increase, VOCs gas is desorbed from the activated carbon.

[0010] Step 5. After desorption, the high-concentration VOCs gas is introduced into the cryogenic equipment for cooling. The refrigerant is passed into the cryogenic equipment to deep-cool the high-concentration VOCs gas to below the specified temperature. The VOCs gas is condensed from the gaseous state into a liquid solvent, and then separated through a gas-liquid separator. The VOCs liquid solvent is stored in a solvent storage tank for recycling in the workshop.

[0011] Preferably, in step five, the VOCs tail gas is condensed by a multi-stage cooling method, and the condensation process includes three stages: pre-cooling, shallow cooling and deep cooling.

[0012] Preferably, after the VOCs tail gas is condensed in step five, a small amount of non-condensable tail gas is separated through a gas-liquid separator and then re-transported to the pretreatment equipment for secondary treatment.

[0013] Preferably, in step three, the activated carbon is circulated and transported between the graphene desorption tower and the adsorption tower through a pair of transport devices.

[0014] A VOCs tail gas recovery device with pressurized desorption, comprising:

[0015] Pretreatment equipment, adsorption tower, graphene desorption tower, cryogenic equipment and gas-liquid separator;

[0016] A high-pressure centrifugal fan is connected between the pretreatment equipment and the adsorption tower. The high-pressure centrifugal fan is used to transport the VOCs tail gas from the pretreatment equipment to the adsorption tower.

[0017] The adsorption tower has an air inlet pipe at the lower end and a chimney at the upper end, and an air distributor, an activated carbon adsorption assembly and a catcher are arranged in sequence from bottom to top.

[0018] The graphene desorption tower is used to desorb the VOCs tail gas adsorbed by the activated carbon, and a pair of conveying devices are connected between the adsorption tower and the graphene desorption tower to convey the activated carbon;

[0019] Among them, a vacuum pump is connected between the cryogenic equipment and the graphene desorption tower. The vacuum pump is used to transport the VOCs tail gas desorbed from the graphene desorption tower to the cryogenic equipment. The cryogenic equipment condenses the desorbed VOCs tail gas. After condensation, the VOCs tail gas is transported to the gas-liquid separator for separation. The separated VOCs liquid solvent is stored in the solvent storage tank.

[0020] Preferably, the activated carbon adsorption assembly includes: a metal mesh with elastic deformation, activated carbon evenly laid on the metal mesh, and a feed pipe fixed in the center of the metal mesh. The feed pipe is provided with feed holes on its circumference, and a feed control valve is connected to the lower end of the feed pipe. The feed control valve is fixedly connected to the discharge pipe through a corrugated hose, and the end of the discharge pipe is connected to the top of the graphene desorption tower.

[0021] Preferably, a mounting frame is fixedly connected inside the adsorption tower, the discharge pipe is fixedly installed on the mounting frame, and a lifting cylinder is installed on the mounting frame, the lifting cylinder is fixedly connected to the lifting frame, and the lifting frame is fixedly connected to the metal mesh.

[0022] Preferably, a transition tank is further provided in the adsorption tower, and a feed pipe is installed on the transition tank, one end of the feed pipe is connected to the bottom of the graphene desorption tower, and a valve core with a hollow structure that can be raised and lowered is movably connected to the bottom of the transition tank, and a valve hole is provided on the circumference of the valve core and a discharge hole is provided at the bottom; and a valve stem is fixedly connected to the lower end of the valve core, and the valve stem is fixedly connected to the discharge pipe.

[0023] Preferably, the conveying device adopts a pneumatic conveying system, which includes an air pump, a conveying pipeline and a valve assembly.

[0024] The beneficial effects of the present invention are:

[0025] 1. The present invention is provided with an adsorption tower and a graphene desorption tower, which are used for adsorption and desorption of activated carbon respectively, thereby saving the desorption time of the adsorption tower and improving the treatment efficiency of VOCs tail gas. In addition, the inner wall of the graphene is coated with a graphene layer to increase the heat radiation effect, and the desorption effect of the activated carbon is better.

[0026] 2. The present invention opens the material control valve, and the lifting cylinder drives the metal mesh to bend downward, so that the activated carbon on the metal mesh can fall into the discharge pipe and be further transported to the graphene desorption tower. The activated carbon in the graphene desorption tower that has been desorbed is transported to the transition tank through the feed pipe for temporary storage. After the activated carbon on the metal mesh is completely transported, the activated carbon in the transition tank is transported to the metal mesh, thereby avoiding mixing of the activated carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the present invention.

[0028] Figure 2This is a schematic structural diagram of the adsorption tower proposed in the present invention.

[0029] Figure 3 This is a schematic structural diagram of the activated carbon adsorption component proposed in the present invention.

[0030] Figure 4 This is a schematic structural diagram of the transition tank proposed in the present invention.

[0031] In the figure: 1. Pretreatment equipment; 2. High-pressure centrifugal fan; 3. Adsorption tower; 31. Air distributor; 32. Activated carbon adsorption assembly; 321. Metal mesh; 322. Activated carbon; 323. Feed pipe; 324. Feed hole; 325. Feed control valve; 326. Corrugated hose; 327. Lifting frame; 328. Mounting frame; 329. Lifting cylinder; 33. Catcher; 34. Transition tank; 341. Valve core; 342. Valve stem; 343. Valve hole; 344. Discharge hole; 35. Air inlet pipe; 36. Chimney; 37. Discharge pipe; 38. Feed pipe; 4. Conveying device; 5. Graphene desorption tower; 6. Gas-liquid separator; 7. Solvent storage tank; 8. Vacuum pump; 9. Cryogenic equipment. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] Example: This example discloses a VOCs tail gas recovery process by pressurized desorption, comprising the following steps:

[0034] Step 1: The workshop's high-volume, low-concentration VOCs exhaust gas passes through the pretreatment equipment 1 to filter out dust, fibers and other particulate matter in the exhaust gas. The pretreatment equipment 1 can filter out particles with a particle size of 5 μm or more to prevent large particles from clogging the pores of the activated carbon 322. At the same time, when necessary, the pretreatment equipment 1 cools the VOCs exhaust gas by circulating cold water. The filtered VOCs exhaust gas is introduced into the adsorption tower 3 through the high-pressure centrifugal fan 2;

[0035] Step 2: The VOCs tail gas passes through the air distributor 31, the activated carbon adsorption assembly 32 and the trap 33 from bottom to top in the adsorption tower 3. The activated carbon adsorption assembly 32 includes granular cylindrical activated carbon 322. The activated carbon 322 is designed to be a granular cylindrical structure for easy transportation in the pipeline. The air distributor 31 is used to evenly distribute the VOCs tail gas in the adsorption tower 3 so that the VOCs tail gas passes evenly through the activated carbon adsorption assembly 32. The VOCs components (organic hydrocarbons, halogenated hydrocarbons, aldehydes, ketones, and lipids) in the exhaust gas are fully absorbed by the activated carbon 322. The trap 33 further captures small particles (≤5μm) in the VOCs tail gas. The treated tail gas is discharged from the chimney 36. At this time, the removal rate of VOCs components in the tail gas can reach more than 99.5%;

[0036] Step 3: When the activated carbon 322 in the adsorption tower 3 adsorbs the VOCs tail gas to saturation, the activated carbon 322 with the VOCs tail gas is transported to the graphene desorption tower 5 through the conveying device 4 for desorption; at the same time, the activated carbon 322 in the graphene desorption tower 5 that has completed desorption is transported to the adsorption tower 3 through the conveying device 4 for reuse, which saves the desorption time of the adsorption tower 3 and improves the working efficiency of the adsorption tower 3;

[0037] Step 4: A heat medium is introduced into the graphene desorption tower 5 to increase the temperature in the graphene desorption tower 5 and heat the activated carbon 322; the graphene desorption tower 5 is coated with a graphene coating to increase the thermal radiation efficiency, and has excellent sealing performance, thereby improving the heat exchange efficiency of the graphene desorption tower 5. At the same time, the graphene desorption tower 5 is evacuated to a vacuum state by a vacuum pump 8, and the vacuum pump 8 simultaneously extracts the desorbed VOCs gas. As the temperature of the graphene desorption tower 5 increases and the pressure decreases, the VOCs gas is continuously desorbed from the activated carbon; wherein, the desorption temperature in the graphene desorption tower 5 is controlled at 110-120°C, and the vacuum desorption pressure is controlled at -0.09MPa to -0.1MPa. The desorption efficiency of the activated carbon can reach more than 95% by the graphene desorption tower 5.

[0038] Step 5: The high-concentration VOCs gas after desorption is introduced into the cryogenic device 9 for cooling. The refrigerant circulates into the cryogenic device 9. The refrigerant uses a refrigerant. The cryogenic device 9 can deep-cool the high-concentration VOCs gas to below a specified temperature. In this embodiment, the specified temperature is -75°C. In this embodiment, the high-concentration VOCs gas is reduced to between -75-110°C, so that the VOCs gas is condensed from a gaseous state into a liquid solvent. In this embodiment, since the temperature required for the condensation of VOCs gas is relatively low, the cryogenic device 9 adopts a multi-stage cooling method to cool the VOCs gas to a temperature below -75°C. The VOCs gas is condensed, and the condensation process includes three stages: pre-cooling, shallow cooling and deep cooling. The temperature in the pre-cooling stage is reduced to 3-5°C, the temperature in the shallow cooling stage is reduced to between -30-50°C, and the temperature in the deep cooling stage is reduced to between -75-1105°C, so that it can eventually be reduced to the condensation temperature of the VOCs gas; the condensed VOCs liquid solvent and part of the uncondensed gas are jointly transported to the gas-liquid separator 6, and the gas and liquid are separated by the gas-liquid separator 6, and the separated VOCs liquid solvent is stored in the solvent storage tank 7 for recycling in the workshop.

[0039] Furthermore, after the VOCs gas is condensed in step five, a small amount of non-condensable tail gas is separated out through the gas-liquid separator 6, and then re-transported to the pretreatment equipment 1 through the pipeline for secondary treatment, and passes through the entire process again together with the workshop VOCs tail gas.

[0040] This embodiment discloses a VOCs tail gas recovery device for pressurized desorption, comprising: a pretreatment device 1, an adsorption tower 3, a graphene desorption tower 5, a cryogenic device 9 and a gas-liquid separator 6; wherein the pretreatment device 1 adopts a horizontal tower structure, and is filled with a primary filter and a high-efficiency filter inside to remove particulate matter with a particle size of ≥5μm, and circulating cold water is introduced into the pretreatment device 1 to cool the VOCs tail gas in the workshop; a high-pressure centrifugal fan 2 is connected between the pretreatment device 1 and the adsorption tower 3, and the high-pressure centrifugal fan 2 is connected to the pretreatment device 1 and the adsorption tower 3 respectively through an air duct, and the high-pressure centrifugal fan 2 transports the VOCs tail gas from the pretreatment device 1 to the adsorption tower 3; an air inlet pipe 35 is provided at the lower end of the adsorption tower 3, and a chimney 36 is installed at the upper end. And the interior thereof is provided with an air distributor 31, an activated carbon adsorption component 32 and a catcher 33 in sequence from bottom to top; VOCs exhaust gas enters from the bottom of the adsorption tower, is guided by the air distributor 31, and the exhaust gas evenly passes through the activated carbon adsorption component 32, and the VOCs components in the exhaust gas are removed by the activated carbon adsorption component 32, and the catcher 33 further filters and removes small particles in the exhaust gas, and the exhaust gas that meets the standards is discharged from the chimney 36; wherein, the graphene desorption tower 5 is used to desorb the VOCs exhaust gas adsorbed by the activated carbon 322, and the inner wall of the graphene desorption tower 5 is coated with a graphene coating, which increases the thermal radiation efficiency and improves the desorption efficiency of the activated carbon 322, and the graphene desorption tower 5 is dedicated to desorbing the activated carbon 322, and the desorption efficiency of the activated carbon 322 is improved. The rate can reach more than 95%; a pair of conveying devices 4 are connected between the adsorption tower 3 and the graphene desorption tower 5, one of which is used to convey the saturated cylindrical activated carbon 322 in the adsorption tower 3 to the graphene desorption tower 5; the other conveying device 4 is used to convey the cylindrical activated carbon 322 that has been desorbed from the graphene desorption tower 5 to the adsorption tower 3; compared with the prior art, the adsorption tower 3 of this embodiment saves the desorption stage of the activated carbon 322, saves time, increases the adsorption working time of the adsorption tower 3, and improves the adsorption efficiency of the adsorption tower 3; a vacuum pump 8 is connected between the deep cooling equipment 9 and the graphene desorption tower 5, and the vacuum pump 8 adopts a Roots vacuum pump, which has the advantages of fast startup, large exhaust volume and high efficiency; the vacuum pump 8 The vacuum degree in the graphene desorption tower 5 is drawn to between -0.09MPa and -0.1MPa. At the same time, the vacuum pump 8 transports the high-concentration VOCs gas desorbed from the graphene desorption tower 5 to the deep-cold equipment 9, wherein the deep-cold equipment 9 includes a compressor, a condenser, a throttle valve and an evaporator. The deep-cold equipment 9 provides an ultra-low temperature cold source through the refrigerant (refrigerant) circulation, and performs multi-stage cooling treatment on the high-concentration VOCs gas, condensing a large amount of high-concentration VOCs tail gas into a liquid solvent. After condensation, the VOCs liquid solvent and some uncondensed gas are transported together to the gas-liquid separator 6 for separation. The separated VOCs liquid solvent is stored in the solvent storage tank 7, and the separated gas is re-transported to the pretreatment equipment 1 for secondary treatment.

[0041] Preferably, the conveying device 4 adopts a pneumatic conveying system to convey the granular cylindrical activated carbon 322 through airflow power, wherein the pneumatic conveying system includes an air pump, a conveying pipeline and a valve assembly, and the air pump adopts a Roots blower with low energy consumption and stable airflow; the conveying pipeline includes a discharge pipe 37 and a feed pipe 38, and the activated carbon 322 is conveyed to the graphene desorption tower 5 through the discharge pipe 37; the activated carbon 322 is conveyed to the adsorption tower 3 through the feed pipe 38.

[0042] like Figure 2-Figure 3 As shown, the activated carbon adsorption component 32 includes: a metal mesh 321 with elastic deformation, activated carbon 322 evenly laid on the metal mesh 321, and a feed pipe 323 fixed at the center of the metal mesh 321. The periphery of the metal mesh 321 is fixedly connected to the inner wall of the adsorption tower 3; the inner edge of the metal mesh 321 is fixedly connected to the feed pipe 323. The filter pores of the metal mesh 321 are smaller than the particle diameter of the activated carbon 322, and the activated carbon 322 will not fall off on the basis of ventilation. The surface of the metal mesh 321 is provided with a material hole 324, and the lower end of the feed pipe 323 is connected to a material control valve 325, which is a solenoid valve. During the adsorption stage, the material control valve 325 is in a closed state. When the activated carbon 322 is evenly laid on the metal mesh 321, due to the fluidity of the activated carbon 322, a small part of the activated carbon 322 will fall into the feed pipe 323 through the material hole 324, which will not affect the normal adsorption of most of the activated carbon 322. The material control valve 325 is fixed by the corrugated hose 326. The discharge pipe 37 is fixedly connected, and the corrugated hose 326 can be stretched and deformed to facilitate the movement of the discharge pipe 323. The end of the discharge pipe 37 is connected to the top of the graphene desorption tower 5; the adsorption tower 3 is fixedly connected with a mounting frame 328, and the discharge pipe 37 is fixedly mounted on the mounting frame 328 through a clamp assembly, and a lifting cylinder 329 is installed on the mounting frame 328. The lifting cylinder 329 is fixedly connected with a lifting frame 327, and the lifting frame 327 is welded to the center position of the lower surface of the metal mesh 321. During specific implementation, when the activated carbon 322 is saturated and needs to be replaced, the introduction of VOCs exhaust gas is first suspended, the material control valve 325 is opened and the conveying device 4 is started, and then the center position of the metal mesh 321 is driven to bend downward by the lifting cylinder 329, and the granular cylindrical activated carbon 322 flows toward the center of the metal mesh 321, enters the feed pipe 323, the material control valve 325 and the discharge pipe 37 in turn through the material hole 324, and is then conveyed to the top of the graphene desorption tower 5 by airflow power.

[0043] Preferably, a transition tank 34 is further provided in the adsorption tower 3 for temporarily receiving the activated carbon 322 transported from the graphene desorption tower 5, so as to avoid the mixing of the activated carbon 322 that has been desorbed and the activated carbon 322 that is saturated with adsorption. A feed pipe 38 is installed on the transition tank 34, one end of the feed pipe 38 is connected to the bottom of the graphene desorption tower 5, and a solenoid valve is installed at one end of the connection, and a valve core 341 of a hollow structure that can be lifted and lowered is movably connected to the bottom of the transition tank 34, and a valve hole 343 is provided on the circumference of the valve core 341, and a discharge port is provided at the bottom. hole 344; and the lower end of the valve core 341 is fixedly connected to the valve stem 342, and the valve stem 342 is fixedly connected to the discharge pipe 323; when the valve core 341 descends, the valve hole 343 descends to a position below the bottom of the transition tank 34, the valve hole 343 is closed, and the activated carbon 322 in the transition tank 34 cannot be discharged through the valve core 341; when the valve core 341 rises, the valve hole 343 rises to a position above the bottom of the transition tank 34, the valve hole 343 opens, and the activated carbon 322 falls onto the metal mesh 321 through the valve hole 343 and the discharge hole 344.

[0044] Activated carbon material replacement process: In this embodiment, when the activated carbon 322 in the adsorption tower 3 is in adsorption operation, the graphene desorption tower 5 is performing desorption operation on the activated carbon 322 therein; when the activated carbon 322 in the adsorption tower 3 is saturated with adsorption and the activated carbon 322 needs to be replaced, the operation of the adsorption tower 3 and the graphene desorption tower 5 is first suspended, and then the material control valve 325 is opened and the conveying device 4 is started, and the discharge pipe 323 is driven down by the lifting cylinder 329, so that the center position of the metal mesh 321 is bent downward. The cylindrical activated carbon 322 flows toward the center of the metal mesh 321, enters the feed pipe 323, the control valve 325 and the discharge pipe 37 in sequence through the material hole 324, and the activated carbon 322 in the discharge pipe 37 is transported to the top of the graphene desorption tower 5 by the air flow power; at the same time, when the feed pipe 323 descends, the valve core 341 is driven to descend, and the valve hole 343 is closed; the activated carbon 322 that has been desorbed at the bottom of the graphene desorption tower 5 is transported to the transition tank 34 through the feed pipe 38 for temporary storage. In the embodiment, the entire material replacement process lasts for about 60 seconds. At 60 seconds, most of the activated carbon in the graphene desorption tower 5 and the adsorption tower 3 is basically replaced. The very small amount of activated carbon 322 that has not been replaced does not affect the entire process. Then, the conveying device 4 and the material control valve 325 are closed, and the lifting cylinder 329 drives the discharge pipe 323 to rise, so that the center position of the metal mesh 321 bends upward, and at the same time drives the valve core 341 to rise, the valve hole 343 is opened, and the activated carbon 322 in the transition tank 34 passes through the valve hole in turn. 343, the discharge hole 344 falls on the metal mesh 321 and flows around. During the discharge process, the lifting cylinder 329 slowly drives the discharge pipe 323 to descend, so that the metal mesh 321 gradually returns to a horizontal state, so that the activated carbon 322 can be evenly laid on the metal mesh 321. When the metal mesh 321 is in a horizontal state, the valve hole 343 is still in an open state, so that the activated carbon 322 in the transition tank 34 can be completely discharged, thereby quickly completing the material replacement process of the activated carbon 322.

[0045] Finally, it should be noted that in the description of the present invention, it should be noted that the terms "vertical", "up", "down", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention.

[0046] The above description is merely 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 aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A VOCs tail gas recovery device with pressurized desorption, characterized in that: include: Pretreatment equipment (1), adsorption tower (3), graphene desorption tower (5), cryogenic equipment (9) and gas-liquid separator (6); A high-pressure centrifugal fan (2) is connected between the pretreatment device (1) and the adsorption tower (3), and the high-pressure centrifugal fan (2) is used to transport the VOCs tail gas from the pretreatment device (1) to the adsorption tower (3); The adsorption tower (3) is provided with an air inlet pipe (35) at the lower end and a chimney (36) at the upper end, and an air distributor (31), an activated carbon adsorption assembly (32) and a catcher (33) are provided in sequence from bottom to top. The graphene desorption tower (5) is used to desorb the VOCs tail gas adsorbed by the activated carbon (322), and a pair of conveying devices (4) are connected between the adsorption tower (3) and the graphene desorption tower (5) for conveying the activated carbon (322); wherein, a vacuum pump (8) is connected between the cryogenic device (9) and the graphene desorption tower (5), and the vacuum pump (8) is used to convey the high-concentration VOCs tail gas desorbed from the graphene desorption tower (5) into the cryogenic device (9), and the cryogenic device (9) condenses the high-concentration VOCs tail gas, and after condensation, the VOCs liquid solvent is conveyed to the gas-liquid separator (6) for separation, and the separated VOCs liquid solvent is stored in the solvent storage tank (7); The activated carbon adsorption assembly (32) comprises: a metal mesh (321) with elastic deformation, activated carbon (322) evenly laid on the metal mesh (321), and a discharge pipe (323) fixed at the center of the metal mesh (321), wherein a material hole (324) is provided on the circumference of the discharge pipe (323), and a control valve (325) is connected to the lower end of the discharge pipe (323), and the control valve (325) is fixedly connected to the discharge pipe (37) via a corrugated hose (326), and the end of the discharge pipe (37) is connected to the top of the graphene desorption tower (5); A mounting frame (328) is fixedly connected to the adsorption tower (3), a discharge pipe (37) is fixedly mounted on the mounting frame (328), a lifting cylinder (329) is mounted on the mounting frame (328), a lifting frame (327) is fixedly connected to the lifting cylinder (329), and the lifting frame (327) is fixedly connected to the metal mesh (321); The adsorption tower (3) is further provided with a transition tank (34), a feed pipe (38) is installed on the transition tank (34), one end of the feed pipe (38) is connected to the bottom of the graphene desorption tower (5), and a valve core (341) with a hollow structure that can be raised and lowered is movably connected to the bottom of the transition tank (34), a valve hole (343) is provided on the circumference of the valve core (341), and a discharge hole (344) is provided at the bottom; and a valve stem (342) is fixedly connected to the lower end of the valve core (341), and the valve stem (342) is fixedly connected to the discharge pipe (323).

2. A pressurized desorption VOCs tail gas recovery device according to claim 1, characterized in that: The conveying device (4) adopts a pneumatic conveying system, which includes an air pump, a conveying pipeline and a valve assembly.

3. A VOCs tail gas recovery process by pressurized desorption, utilizing a VOCs tail gas recovery device by pressurized desorption as claimed in claim 2, characterized in that: The following steps are involved: Step 1: The VOCs tail gas in the workshop is filtered through the pretreatment equipment (1) to filter the particulate matter in the tail gas, and then introduced into the adsorption tower (3) through the high-pressure centrifugal fan (2); Step 2: The VOCs exhaust gas passes through the air distributor (31), the activated carbon adsorption component (32) and the capture device (33) from bottom to top in the adsorption tower (3). The VOCs components in the exhaust gas are fully adsorbed by the activated carbon. After meeting the standards, the exhaust gas is discharged from the chimney (36); Step 3: The activated carbon (322) adsorbed with VOCs in the adsorption tower (3) is transported to the graphene desorption tower (5) for desorption; at the same time, the activated carbon (322) that has been desorbed in the graphene desorption tower (5) is transported to the adsorption tower (3) for reuse; Step 4: A heat medium is introduced into the graphene desorption tower (5) to heat the activated carbon (322). At the same time, the graphene desorption tower (5) is evacuated to a vacuum state by a vacuum pump (8). As the vacuum degree and temperature in the tower increase, the VOCs gas is desorbed from the activated carbon. Step 5: The high-concentration VOCs gas after desorption is introduced into the cryogenic equipment (9) for cooling. The refrigerant is introduced into the cryogenic equipment (9) to deep-cool the high-concentration VOCs gas to below the specified temperature. The VOCs gas is condensed from the gaseous state into a liquid solvent, and then separated by the gas-liquid separator (6). The VOCs liquid solvent is stored in the solvent storage tank (7) for recycling in the workshop.

4. The VOCs tail gas recovery process by pressurized desorption according to claim 3, characterized in that: In step 5, the VOCs tail gas is condensed by a multi-stage cooling method, and the condensation process includes three stages: pre-cooling, shallow cooling and deep cooling.

5. A VOCs tail gas recovery process by pressurized desorption according to claim 4, characterized in that: After the VOCs tail gas is condensed in step 5, a small amount of non-condensable tail gas is separated through the gas-liquid separator (6) and then re-transported to the pretreatment equipment (1) for secondary treatment.

6. The VOCs tail gas recovery process by pressurized desorption according to claim 5, characterized in that: In step 3, the activated carbon (322) is circulated and transported between the graphene desorption tower (5) and the adsorption tower (3) through a pair of transport devices (4).

Images