A VOC normal-temperature condensation treatment system and method using the static activity of activated carbon

Abstract

The present invention discloses a VOC room-temperature condensation treatment system and method utilizing the static activity of activated carbon, relating to the technical field of industrial VOCs treatment. The system comprises a VOCs pretreatment system, a desorption condensation system, an auxiliary adsorption bed C, an adsorption bed A, and an adsorption bed B; adsorption beds A and B are connected to an adsorption blower via an adsorption inlet valve; the adsorption blower is connected to the VOCs pretreatment system; adsorption beds A and B are connected to the atmosphere via an adsorption outlet valve; adsorption beds A and B are connected in series via series valves Ab and Ba; and the ends of adsorption bed A, adsorption bed B, and auxiliary adsorption bed C are connected to the ends of the desorption condensation system via desorption condensation valves. The treatment method using the system of the present invention fully utilizes the static activity of activated carbon, reduces the cost of activated carbon, extends its service life, and recovers organic solvents of high purity and high recovery efficiency. The "2+1" model simplifies the control strategy and makes operation more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial emission VOCs treatment, and in particular to a VOC room-temperature condensation treatment system and method utilizing the static activity of activated carbon. Background Art

[0002] Volatile organic compounds (VOCs) in the atmosphere cause serious harm to plant and animal life and impact human health, such as eye irritation, respiratory problems, and cancer. VOCs, used as organic solvents in industries such as spray painting and furniture, can account for 35-40% of atmospheric VOC emissions. In these industries, common VOC treatment methods include recovery methods such as adsorption, absorption, and condensation, and destruction methods such as direct combustion, catalytic oxidation, biological treatment, low-temperature plasma, and photocatalysis. In practical applications, two or three of these methods are generally combined. The VOC treatment method of activated carbon adsorption and concentration combined with condensation recovery is more convenient and simple to handle, and is highly cost-effective, making it an ideal treatment method.

[0003] Luo Fukun et al. proposed a process for treating organic waste gas using activated carbon adsorption and nitrogen desorption recovery. After adsorption, the gas is desorbed using nitrogen vacuum at 4-10 kPa and then condensed in a two-stage condensation unit. Remaining VOCs are purged with fresh air and then sent to another adsorber for adsorption. This patent effectively desorbs and condenses VOCs, but the final fresh air purge still poses safety risks and reduces the lifespan of the activated carbon. He Yani et al. proposed an activated carbon adsorption hot nitrogen desorption condensation recovery system. After desorption, the gas is condensed using a three-stage condensation process. Non-condensable gases in the pipeline are then adsorbed in an auxiliary activated carbon adsorber. However, this patent still suffers from the high energy consumption of the three-stage condensation process, as well as the high thermal stress and airtightness requirements of the equipment.

[0004] I have also proposed a VOCs treatment system and method for room-temperature condensation-assisted purification, which utilizes three identical beds in rotation for adsorption purification, desorption condensation, and auxiliary purification. This achieves very little bed residue after desorption and condensation, ensuring that VOCs emission concentrations meet standards during the normal adsorption cycle. This patent achieves room-temperature condensation while ensuring adsorption efficiency meets standards, reducing process difficulty, equipment costs, and operating energy consumption. However, like other similar patents, this patent only utilizes the dynamic activity of activated carbon and places high demands on the activated carbon's adsorption and desorption performance, requiring that the adsorption capacity during auxiliary adsorption be greater than the sum of the condensation residue and the dynamic adsorption capacity. Otherwise, insufficient transfer will occur, resulting in substandard emission concentrations after adsorption purification.

[0005] At present, the adsorption, concentration, and condensation recovery methods of VOCs generally face the following four problems: deep condensation is required, so the energy consumption of condensation and heating is greatly increased; the system equipment, pipelines and valves are subjected to large temperature differences, resulting in stress loss and difficulty in meeting air tightness requirements; some VOCs still remain in the adsorption bed after condensation, resulting in a decrease in the adsorption efficiency of the next stage or the risk of explosion when using fresh air hot purge; only the adsorption kinetic activity of activated carbon is utilized, wasting part of the adsorption capacity of activated carbon. Summary of the Invention

[0006] The purpose of the present invention is to provide a VOC room-temperature condensation treatment system and method utilizing the static activity of activated carbon, so as to solve the problems existing in the above-mentioned prior art, make full use of the adsorption capacity of activated carbon, save the use of activated carbon, and at the same time realize the liquefaction and recovery of VOCs using conventional high-efficiency cold sources or even natural cold sources, thereby greatly reducing condensation energy consumption and equipment costs.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a VOC room-temperature condensation treatment system utilizing the static activity of activated carbon, comprising a VOCs pretreatment system, a desorption condensation system, and an auxiliary adsorption bed C, wherein two parallel adsorption beds A and B are provided on one side of the auxiliary adsorption bed C; the adsorption bed A is connected to an adsorption fan through an adsorption air inlet valve Aa1, and the adsorption bed B is connected to the adsorption fan through an adsorption air inlet valve Ba1; the adsorption fan is connected to the VOCs pretreatment system; the adsorption bed A is connected to the atmosphere through an adsorption air outlet valve Aa2, and the adsorption bed B is connected to the atmosphere through an adsorption air outlet valve Ba2; the adsorption bed A and the adsorption bed B are connected in series via a series valve Ab and a series valve Ba; both ends of the adsorption bed A are respectively connected to both ends of the desorption condensation system through a desorption condensation valve Ad1 and a desorption condensation valve Ad2, both ends of the adsorption bed B are respectively connected to both ends of the desorption condensation system through a desorption condensation valve Bd1 and a desorption condensation valve Bd2, and both ends of the adsorption bed C are respectively connected to both ends of the desorption condensation system through a desorption condensation valve Cd1 and a desorption condensation valve Cd2. The operating conditions of the adsorption bed A and the adsorption bed B include single-bed adsorption, front series adsorption, desorption condensation, purification transfer and back series adsorption, and the operating conditions of the auxiliary adsorption bed C include auxiliary adsorption and desorption condensation.

[0009] Optionally, the desorption condensation system includes an air-to-air heat exchanger, a normal temperature condensation system, a three-way butterfly valve, a desorption fan, a stop valve and a heater connected in series in sequence; the three-way butterfly valve includes a passage I, a passage II and a passage III, the normal temperature condensation system is connected to the passage I, the desorption fan is connected to the passage II, the connecting pipeline between the passage II and the desorption fan is connected to a first branch connected to the air-to-air heat exchanger, and the passage III is connected to the air-to-air heat exchanger through a second branch; the auxiliary adsorption bed C is connected to both ends of the stop valve through valve Cp1 and valve Cp2; the desorption condensation valve Ad1, the desorption condensation valve Bd1 and the desorption condensation valve Cd1 are connected to the heater through a first desorption condensation pipeline, and the desorption condensation valve Ad2, the desorption condensation valve Bd2 and the desorption condensation valve Cd2 are connected to the air-to-air heat exchanger through a second desorption condensation pipeline.

[0010] Optionally, a nitrogen replenishment system is also included, which includes a nitrogen source and an online oxygen content detector. The nitrogen source is connected to the second desorption condensation pipe through a nitrogen replenishment valve n1, and the first desorption condensation pipe is connected to a nitrogen replenishment valve n2. The nitrogen replenishment valve n2 is connected to the adsorption pipe at the front end of the VOCs pretreatment system through an online oxygen content detector.

[0011] Optionally, a VOCs concentration sensor Av is provided between the adsorption bed A and the adsorption outlet valve Aa2, a VOCs concentration sensor Bv is provided between the adsorption bed B and the adsorption outlet valve Ba2, a VOCs concentration sensor Cv is provided between the gas-to-gas heat exchanger and the normal temperature condensation system, and a VOCs concentration sensor Dv is provided between one end of the stop valve and the valve Cp2.

[0012] Optionally, the room temperature condensation system includes a VOCs liquid storage tank and a room temperature condenser, and the room temperature condenser can adopt a conventional high-efficiency cold source or a natural cold source.

[0013] Optionally, both the adsorption fan and the desorption fan are explosion-proof variable frequency fans.

[0014] The present invention also provides a treatment method for a VOC room temperature condensation treatment system utilizing the above-mentioned activated carbon static activity, comprising the following steps:

[0015] Step 10: Equipment debugging: Close all adsorption air inlet valves Aa1 and Ba1 and all adsorption air outlet valves Aa2 and Ba2, open all remaining valves, and then turn on the nitrogen source to replace the gas in the system pipelines and equipment with nitrogen. When the online oxygen content detector shows that the oxygen content is lower than 5%, close all valves and the nitrogen source;

[0016] Step 20: Open the adsorption inlet valve Aa1 and the adsorption outlet valve Aa2. The organic waste gas is cooled and particle-removed by the pretreatment system and then sent to the adsorption bed A. After being purified to meet the standards, it is discharged into the atmosphere.

[0017] Step 30: When the VOCs concentration sensor Av after adsorption bed A displays a value that reaches 50% of the emission standard, close the adsorption outlet valve Aa2, open the series valve Ab, and connect adsorption bed B in series behind adsorption bed A. The exhaust gas passes through adsorption bed A and adsorption bed B in sequence and is then discharged into the atmosphere until the VOCs concentration sensor Av displays that adsorption bed A has reached saturation adsorption capacity and cannot continue to adsorb. Then, adsorption bed A enters the desorption stage, and adsorption bed B continues to adsorb.

[0018] Step 40: Before desorbing the adsorption bed A, open the nitrogen replenishment valve n1, the nitrogen replenishment valve n2, and the nitrogen source to replace the gas in the adsorption bed A with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector shows that the oxygen content is lower than 5%, close the nitrogen replenishment valve n1, the nitrogen replenishment valve n2, and the nitrogen source; then, open the desorption condensation valve Ad1, the desorption condensation valve Ad2, the stop valve, the desorption fan, and the heater in sequence, and switch the three-way butterfly valve to the three-way positions I and III. When the VOCs concentration sensor Cv displays the condensation concentration, open the condensation system until no condensate flows out;

[0019] Step 50: Close the stop valve, open valves Cp1 and Cp2, and switch the three-way butterfly valve to passages I and II. The high-temperature, high-concentration VOCs gas from adsorption bed A is cooled and then sent to adsorption bed C for adsorption to become low-concentration gas and then heated. At this time, VOCs in adsorption bed A can continue to be desorbed until the VOCs concentration sensor Cv indicates that no more VOCs are desorbed from adsorption bed A. Then, open the stop valve, close valves Cp1, Cp2, and the heater to cool the activated carbon in adsorption bed A.

[0020] Step 60: When the VOCs concentration sensor Bv after adsorption bed B shows a value reaching 50% of the emission standard, the adsorption outlet valve Ba2 is closed and the series valve Ba is opened. Adsorption bed A is connected in series behind adsorption bed B, and the exhaust gas passes through adsorption bed B and adsorption bed A in sequence before being discharged into the atmosphere until the VOCs concentration sensor Bv shows that adsorption bed B has reached saturation adsorption capacity and can no longer adsorb. Then, adsorption bed B enters the desorption stage, and adsorption bed A continues to adsorb.

[0021] Step 70: Before desorption of adsorption bed B, open nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source to replace the gas in adsorption bed B with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector shows that the oxygen content is lower than 5%, close nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source; then, open desorption condensation valve Bd1, desorption condensation valve Bd2, stop valve, desorption fan, and heater in sequence, and switch the three-way butterfly valve to passage I and passage III. When the VOCs concentration sensor Cv displays the value reaching the condensation concentration, open the condensation system until no condensate flows out;

[0022] Step 80: Close the stop valve, open valves Cp1 and Cp2, and switch the three-way butterfly valve to the I and II positions. The high-temperature, high-concentration VOCs gas from adsorption bed B is cooled and then sent to adsorption bed C for adsorption to become low-concentration gas and then heated. At this time, VOCs in adsorption bed B can continue to be desorbed until the VOCs concentration sensor Cv indicates that no more VOCs are desorbed from adsorption bed B. Then, open the stop valve, close valves Cp1, Cp2, and the heater to cool the activated carbon in adsorption bed B.

[0023] Step 90: Repeat the above steps 30-80;

[0024] Step 100. When the VOCs concentration sensor Dv behind the auxiliary adsorption bed C shows that the adsorption bed C has reached the set transfer limit, open the desorption condensation valve Cd1, the desorption condensation valve Cd2 and the stop valve, switch the three-way butterfly valve to the I channel and the III channel, turn on the desorption fan and the heater, and when the VOCs concentration sensor Cv displays the value reaching the condensation concentration, turn on the condensation system until no condensate flows out, turn off the heater, and cool down the activated carbon in the adsorption bed C.

[0025] Compared with the prior art, the present invention has achieved the following technical effects:

[0026] The present invention provides a VOCs room-temperature condensation treatment system and method utilizing the static activity of activated carbon. Based on the breakthrough curve characteristics of activated carbon for VOCs and the characteristics of activated carbon adsorption isotherms, the system operates in a 2+1 mode. "2" represents two identical beds (A and B) that alternate in adsorption, directly treating exhaust gas. Operating conditions include single-bed adsorption, pre-series adsorption, desorption condensation, purification transfer, and post-series adsorption. "1" represents the auxiliary bed (C). Bed C is typically filled with more activated carbon than beds A and B and does not adsorb or purify exhaust gas. Operating conditions include auxiliary adsorption and desorption condensation. By utilizing the static activity of activated carbon and employing room-temperature condensation in conjunction with a carefully matched auxiliary adsorption bed for auxiliary purification, costs and system energy consumption are reduced, while VOC solvent recovery is highly efficient. Based on the breakthrough curve characteristics of activated carbon for VOCs, the system switches to a series mode when the adsorption bed is about to break through, completely saturating the activated carbon in that bed. This significantly reduces activated carbon cost and bed volume when designing the activated carbon adsorption bed. Adopting room-temperature condensation avoids deep condensation, reduces energy consumption and process difficulty, and reduces the temperature difference of the fluid in the system, lowering the thermal stress requirements of equipment and pipelines, making the entire solution economically feasible. Strictly matching the activated carbon dosage of the auxiliary adsorption bed allows the auxiliary adsorption bed to completely adsorb the VOCs remaining in adsorption bed A or B after condensation, so that the adsorption efficiency of adsorption bed A and B in the next cycle can still be maintained at a high level. Moreover, after the adsorption is completed, the auxiliary adsorption bed can further desorb and condense the desorbed VOCs for recovery, thereby maintaining a high VOC recovery rate and a higher VOC concentration after desorption from the auxiliary bed, which also improves the condensation efficiency and reduces the condensation energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Schematic diagram of a VOCs room temperature condensation treatment system utilizing the static activity of activated carbon according to the present invention;

[0029] Among them, 1 is the VOCs pretreatment system, 2 is the adsorption fan, 3 is the nitrogen source, 4 is the online oxygen content detector, 5 is the gas-to-gas heat exchanger, 6 is the normal temperature condensation system, 7 is the three-way butterfly valve, 8 is the desorption fan, 9 is the heater, and 10 is the stop valve. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The purpose of the present invention is to provide a VOC room-temperature condensation treatment system and method utilizing the static activity of activated carbon, so as to solve the problems existing in the above-mentioned prior art, make full use of the adsorption capacity of activated carbon, save the use of activated carbon, and at the same time realize the liquefaction and recovery of VOCs using conventional high-efficiency cold sources or even natural cold sources, thereby greatly reducing condensation energy consumption and equipment costs.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention provides a VOCs room temperature condensation treatment system and method using the static activity of activated carbon, such as Figure 1 As shown, the system includes: two parallel adsorption beds A and B, an auxiliary adsorption bed C, a VOCs pretreatment system 1, a nitrogen replenishment system and a desorption condensation system. The adsorption beds A and B are connected to the VOCs pretreatment system 1 and the adsorption fan 2 through the adsorption inlet valve Aa1 and the adsorption inlet valve Ba1, and are connected to the atmosphere through the adsorption outlet valve Aa2 and the adsorption outlet valve Ba2. The adsorption beds A and B are connected through the series valve Ab and the series valve Ba; the adsorption beds A, B and the auxiliary adsorption bed C are connected through the desorption condensation valve Ad1, the desorption condensation valve Ad2, the desorption condensation valve Bd1, the desorption condensation valve Bd2, the desorption condensation valve Cd1, the desorption condensation valve Cd2 is connected to the desorption condensation system, which includes an air-to-air heat exchanger 5, a normal temperature condensation system 6, a three-way butterfly valve 7, a desorption fan 8, a heater 9 and a stop valve 10; the nitrogen replenishment system is connected to the desorption condensation pipeline through the nitrogen replenishment valve n1 and the nitrogen replenishment valve n2, and the other side of the nitrogen replenishment valve n2 is connected to the adsorption pipeline at the front end of the VOCs pretreatment system 1. The nitrogen replenishment system includes a nitrogen source 3 and an online oxygen content detector 4; the auxiliary adsorption bed C is also connected to both sides of the stop valve 10 through valves Cp1 and Cp2.

[0034] The processing method of the present invention has the following steps:

[0035] Step 10. During the equipment debugging phase, close all adsorption air inlet valves Aa1 and Ba1 and all adsorption air outlet valves Aa2 and Ba2, open all remaining valves, and then turn on the nitrogen source to replace the gas in the system pipelines and equipment with nitrogen. When the online oxygen content detector 4 shows that the oxygen content is lower than 5%, close all valves and the nitrogen source 3.

[0036] Step 20: Synchronously start the adsorption fan 2 along with the production line, open the adsorption air inlet valve Aa1 and the adsorption air outlet valve Aa2, and the organic waste gas is sent to the adsorption bed A after being cooled and particle-removed by the pretreatment system. After being purified to meet the standards, it is discharged into the atmosphere.

[0037] Step 30: When the VOCs concentration sensor Av after adsorption bed A displays a value that reaches 50% of the emission standard, close the adsorption valve Aa2, open the series valve Ab, increase the frequency of adsorption fan 2 to maintain the adsorption air volume unchanged, and connect adsorption bed B in series behind adsorption bed A. The exhaust gas passes through adsorption bed A and adsorption bed B in sequence and is then discharged into the atmosphere until the VOCs concentration sensor Av displays that adsorption bed A has reached saturation adsorption capacity and cannot continue adsorption. Then, adsorption bed A enters the desorption stage, and the frequency of adsorption fan 2 is reduced to maintain the adsorption air volume unchanged, while adsorption bed B continues adsorption.

[0038] Step 40: Before desorption of adsorption bed A, open nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source 3 to replace the gas in adsorption bed A with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector 4 shows that the oxygen content is lower than 5%, close nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source 3; then, open desorption condensation valve Ad1, desorption condensation valve Ad2, stop valve, desorption fan, and heater in sequence, and switch the three-way butterfly valve to channels I and III. When the VOCs concentration sensor Cv displays a condensation concentration, open the condensation system until no condensate flows out.

[0039] Step 50: At this time, no VOCs are desorbed from the adsorption bed A, but the residual condensed VOCs in the adsorption bed A will affect the adsorption efficiency of the next cycle. Therefore, the residual VOCs in the adsorption bed A need to be transferred to the auxiliary adsorption bed C; close the stop valve 10, open the valve Cp1 and the valve Cp2, switch the three-way butterfly valve 7 to the I channel and the II channel, increase the frequency of the desorption fan 8 to keep the desorption air volume unchanged, and send the high-temperature and high-concentration VOCs gas from the adsorption bed A to the adsorption bed C after cooling to be adsorbed into a low-concentration gas and then heated. At this time, the VOCs in the adsorption bed A can continue to be desorbed until the VOCs concentration sensor Cv shows that no VOCs are desorbed from the adsorption bed A. Then, open the stop valve 10, close the valves Cp1, Cp2 and the heater to cool the activated carbon in the adsorption bed A, and then turn off the desorption fan 2, the condensation system 6, the desorption condensation valve Ad1, the desorption condensation valve Ad2 and the stop valve 10 in sequence;

[0040] Step 60: When the VOCs concentration sensor Bv after adsorption bed B displays a value reaching 50% of the emission standard, close the adsorption valve Ba2, open the series valve Ba, increase the frequency of the adsorption fan 2 to maintain the adsorption air volume unchanged, and connect adsorption bed A in series behind adsorption bed B. The exhaust gas passes through adsorption beds B and A in sequence and is then discharged into the atmosphere until the VOCs concentration sensor Bv displays that adsorption bed B has reached saturation adsorption capacity and cannot continue adsorption. Then, adsorption bed B enters the desorption stage, and the frequency of the adsorption fan 2 is reduced to maintain the adsorption air volume unchanged. Adsorption bed A continues adsorption.

[0041] Step 70: Before desorption of adsorption bed B, open nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source 3 to replace the gas in adsorption bed B with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector 4 shows that the oxygen content is lower than 5%, close nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source 3; then, open desorption condensation valve Bd1, desorption condensation valve Bd2, stop valve 10, desorption fan 8, and heater 9 in sequence, and switch the three-way butterfly valve 7 to passage I and passage III. At this time, the high-temperature nitrogen desorbs the VOCs in adsorption bed B. When the value displayed by the VOCs concentration sensor Cv reaches the condensation concentration, open the condensation system 6 until no condensate flows out.

[0042] Step 80: At this time, no VOCs are desorbed from the adsorption bed B, but the residual condensed VOCs in the adsorption bed B will affect the adsorption efficiency of the next cycle. Therefore, the residual VOCs in the adsorption bed B need to be transferred to the auxiliary adsorption bed C; close the stop valve 10, open the valve Cp1 and the valve Cp2, switch the three-way butterfly valve 7 to the I channel and II channel positions, increase the frequency of the desorption fan 8 to keep the desorption air volume unchanged, and send the high-temperature and high-concentration VOCs gas from the adsorption bed B to the adsorption bed C after cooling to be adsorbed into a low-concentration gas and then heated. At this time, the VOCs in the adsorption bed B can continue to be desorbed until the VOCs concentration sensor Cv shows that no VOCs are desorbed from the adsorption bed B. Then, open the stop valve 10, close the valves Cp1, Cp2 and the heater to cool the activated carbon in the adsorption bed B, and then turn off the desorption fan 2, the condensation system 6, the desorption condensation valve Bd1, the desorption condensation valve Bd2 and the stop valve 10 in sequence;

[0043] Step 90: Repeat steps 30-80 above

[0044] Step 100. When the VOCs concentration sensor Dv behind the auxiliary adsorption bed C shows that the adsorption bed C has reached the transfer limit, open the desorption condensation valve Cd1, the desorption condensation valve Cd2, and the stop valve 10, switch the three-way butterfly valve to the I channel and the III channel, turn on the desorption fan 8 and the heater 9, and when the VOCs concentration sensor Cv displays the value reaching the condensation concentration, turn on the condensation system 6 until no condensate flows out, turn off the heater 9, and cool down the activated carbon in the adsorption bed C.

[0045] For a given activated carbon, the saturated adsorption capacity qb depends on the VOCs emission concentration, exhaust temperature and VOCs type; the condensation concentration Cc depends on the VOCs type and condensation temperature; the VOCs condensation residual amount qr depends on the desorption temperature and condensation concentration Cc; the transfer limit amount qc depends on the condensation temperature and desorption concentration Cd; mc(qc-qr)≥Nmqr. When designing the auxiliary adsorption bed, the equal sign can be used to calculate the activated carbon dosage and retain a 20% surplus, where N represents the number of transfers.

[0046] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for treating VOCs by condensing at room temperature using the static activity of activated carbon, characterized in that: The VOC room temperature condensation treatment system comprises an activated carbon statically activated VOC, which comprises a VOCs pretreatment system, a desorption condensation system and an auxiliary adsorption bed C. Two parallel adsorption beds A and B are provided on one side of the auxiliary adsorption bed C; the adsorption bed A is connected to the adsorption fan through the adsorption air inlet valve Aa1, and the adsorption bed B is connected to the adsorption fan through the adsorption air inlet valve Ba1; the adsorption fan is connected to the VOCs pretreatment system; the adsorption bed A is connected to the atmosphere through the adsorption air outlet valve Aa2 The adsorption bed B is connected to the atmosphere through the adsorption outlet valve Ba2; the adsorption bed A and the adsorption bed B are connected in series through the series valve Ab and the series valve Ba; the two ends of the adsorption bed A are connected to the two ends of the desorption condensation system through the desorption condensation valve Ad1 and the desorption condensation valve Ad2, respectively, the two ends of the adsorption bed B are connected to the two ends of the desorption condensation system through the desorption condensation valve Bd1 and the desorption condensation valve Bd2, respectively, and the two ends of the auxiliary adsorption bed C are connected to the two ends of the desorption condensation system through the desorption condensation valve Cd1 and the desorption condensation valve Cd2; The operating conditions of the adsorption bed A and the adsorption bed B include single-bed adsorption, front series adsorption, desorption condensation, purification transfer and rear series adsorption, and the operating conditions of the auxiliary adsorption bed C include auxiliary adsorption and desorption condensation; the desorption condensation system includes an air-to-air heat exchanger, a normal temperature condensation system, a three-way butterfly valve, a desorption fan, a stop valve and a heater connected in series in sequence; the three-way butterfly valve includes an I passage, a II passage and a III passage, the normal temperature condensation system is connected to the I passage, the desorption fan is connected to the II passage, and the connecting pipe between the II passage and the desorption fan is A first branch connected to the gas-to-gas heat exchanger is connected, and the III passage is connected to the gas-to-gas heat exchanger through a second branch; the auxiliary adsorption bed C is connected to both ends of the stop valve through valves Cp1 and Cp2; the desorption condensation valve Ad1, the desorption condensation valve Bd1, and the desorption condensation valve Cd1 are connected to the heater through a first desorption condensation pipeline, and the desorption condensation valve Ad2, the desorption condensation valve Bd2, and the desorption condensation valve Cd2 are connected to the gas-to-gas heat exchanger through a second desorption condensation pipeline; the treatment method comprises the following steps: Step 10: Equipment debugging: Close the adsorption air inlet valve Aa1, the adsorption air inlet valve Ba1, the adsorption air outlet valve Aa2, and the adsorption air outlet valve Ba2, open all remaining valves, and then turn on the nitrogen source to replace the gas in the system pipeline and equipment with nitrogen. When the online oxygen content detector shows that the oxygen content is less than 5%, close all valves and the nitrogen source; Step 20: Open the adsorption inlet valve Aa1 and the adsorption outlet valve Aa2. The organic waste gas is cooled and particle-removed by the pretreatment system and then sent to the adsorption bed A. After being purified to meet the standards, it is discharged into the atmosphere. Step 30: When the VOCs concentration sensor Av after adsorption bed A displays a value that reaches 50% of the emission standard, close the adsorption outlet valve Aa2, open the series valve Ab, and connect adsorption bed B in series behind adsorption bed A. The exhaust gas passes through adsorption bed A and adsorption bed B in sequence and is then discharged into the atmosphere until the VOCs concentration sensor Av displays that adsorption bed A has reached saturation adsorption capacity and cannot continue to adsorb. Then, adsorption bed A enters the desorption stage, and adsorption bed B continues to adsorb. Step 40: Before desorbing the adsorption bed A, open the nitrogen replenishment valve n1, the nitrogen replenishment valve n2, and the nitrogen source to replace the gas in the adsorption bed A with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector shows that the oxygen content is lower than 5%, close the nitrogen replenishment valve n1, the nitrogen replenishment valve n2, and the nitrogen source; then, open the desorption condensation valve Ad1, the desorption condensation valve Ad2, the stop valve, the desorption fan, and the heater in sequence, and switch the three-way butterfly valve to the three-way positions I and III. When the VOCs concentration sensor Cv displays the condensation concentration, open the condensation system until no condensate flows out; Step 50: Close the stop valve, open valves Cp1 and Cp2, and switch the three-way butterfly valve to passages I and II. The high-temperature, high-concentration VOCs gas from adsorption bed A is cooled and then sent to auxiliary adsorption bed C for adsorption to become low-concentration gas and then heated. At this time, VOCs in adsorption bed A can continue to be desorbed until the VOCs concentration sensor Cv indicates that no more VOCs are desorbed from adsorption bed A. Then, open the stop valve, close valves Cp1, Cp2, and the heater, and cool the activated carbon in adsorption bed A. Step 60: When the VOCs concentration sensor Bv after adsorption bed B shows a value reaching 50% of the emission standard, the adsorption outlet valve Ba2 is closed and the series valve Ba is opened. Adsorption bed A is connected in series behind adsorption bed B, and the exhaust gas passes through adsorption bed B and adsorption bed A in sequence before being discharged into the atmosphere until the VOCs concentration sensor Bv shows that adsorption bed B has reached saturation adsorption capacity and can no longer adsorb. Then, adsorption bed B enters the desorption stage, and adsorption bed A continues to adsorb. Step 70: Before desorption of adsorption bed B, open nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source to replace the gas in adsorption bed B with nitrogen and send it into the adsorption pipeline. When the online oxygen content detector shows that the oxygen content is lower than 5%, close nitrogen replenishment valve n1, nitrogen replenishment valve n2, and nitrogen source; then, open desorption condensation valve Bd1, desorption condensation valve Bd2, stop valve, desorption fan, and heater in sequence, and switch the three-way butterfly valve to passage I and passage III. When the VOCs concentration sensor Cv displays the value reaching the condensation concentration, open the condensation system until no condensate flows out; Step 80: Close the stop valve, open valves Cp1 and Cp2, and switch the three-way butterfly valve to the I and II positions. The high-temperature, high-concentration VOCs gas from adsorption bed B is cooled and then sent to the auxiliary adsorption bed C for adsorption to become low-concentration gas and then heated. At this time, the VOCs in adsorption bed B can continue to be desorbed until the VOCs concentration sensor Cv indicates that no more VOCs are desorbed from adsorption bed B. Then, open the stop valve, close valves Cp1, Cp2, and the heater, and cool the activated carbon in adsorption bed B. Step 90: Repeat the above steps 30-80; Step 100. When the VOCs concentration sensor Dv behind the auxiliary adsorption bed C shows that the auxiliary adsorption bed C has reached the set transfer limit, open the desorption condensation valve Cd1, the desorption condensation valve Cd2 and the stop valve, switch the three-way butterfly valve to the I channel and the III channel, turn on the desorption fan and the heater, and when the VOCs concentration sensor Cv displays the value reaching the condensation concentration, turn on the condensation system until no condensate flows out, turn off the heater, and cool down the activated carbon in the auxiliary adsorption bed C.

2. The method for treating VOCs by condensing at room temperature using the static activity of activated carbon according to claim 1, characterized in that: It also includes a nitrogen replenishment system, which includes a nitrogen source and an online oxygen content detector. The nitrogen source is connected to the second desorption condensation pipeline through a nitrogen replenishment valve n1. The first desorption condensation pipeline is connected to a nitrogen replenishment valve n2. The nitrogen replenishment valve n2 is connected to the adsorption pipeline at the front end of the VOCs pretreatment system through an online oxygen content detector.

3. The method for treating VOCs by condensing at room temperature using the static activity of activated carbon according to claim 1, characterized in that: A VOCs concentration sensor Av is arranged between the adsorption bed A and the adsorption outlet valve Aa2, a VOCs concentration sensor Bv is arranged between the adsorption bed B and the adsorption outlet valve Ba2, a VOCs concentration sensor Cv is arranged between the gas-to-gas heat exchanger and the normal temperature condensation system, and a VOCs concentration sensor Dv is arranged between one end of the stop valve and the valve Cp2.

4. The method for treating VOCs by condensing at room temperature using the static activity of activated carbon according to claim 1, characterized in that: The normal temperature condensation system includes a VOCs liquid storage tank and a normal temperature condenser, and the normal temperature condenser can adopt a natural cold source.

5. The method for treating VOCs by condensing at room temperature using the static activity of activated carbon according to claim 1, characterized in that: The adsorption fan and the desorption fan are both explosion-proof variable frequency fans.

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