A system and method for adsorptive condensation recovery of vocs

Abstract

This invention provides a VOCs adsorption-condensation-recovery device system and method. The VOCs adsorption-condensation-recovery device system includes: a filtration device, an adsorption unit, a nitrogen storage device, a heating device, a condensation unit, and a chimney. The filtration device is connected to the adsorption unit. A circulation loop is formed between the adsorption unit, the nitrogen storage device, the heating device, and the condensation unit. The chimney is connected to the condensation unit. The method uses this device system. The VOCs adsorption-condensation-recovery device system and method provided by this invention can remove and recover VOCs from flue gas with low concentration and high moisture content. The VOCs removal rate is above 92.1%, especially above 97.8%, and the recovery rate can reach above 97%. It uses a small amount of adsorbent, has high treatment efficiency, low cost, and no secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of waste gas treatment and relates to a VOCs treatment process, specifically a VOCs adsorption, condensation and recovery device system and method. Background Technology

[0002] Volatile organic compounds (VOCs) refer to volatile hydrocarbons and their derivatives, including hydrocarbons, aromatics, alcohols, aldehydes, ketones, esters, amines, and organic acids. VOCs not only cause serious environmental pollution problems but also harm human health, posing a great threat to environmental safety and human survival.

[0003] The coking industry is a significant source of VOCs emissions. The VOCs emitted from coking plants are diverse in composition, with numerous emission points and varying characteristics at each point. The chemical production area and coking wastewater treatment are the primary sources of VOCs emissions. The chemical production area, including the cooling drum section, desulfurization section, ammonium sulfate section, and benzene removal section, is the region that generates the most VOCs in the entire process, producing large quantities of fugitive VOCs characterized by low VOC concentrations and high water content.

[0004] CN113069874A discloses a VOCs treatment system and process suitable for coking plant production areas. It treats waste gas from tar storage tanks, coal gas purification ammonia-water circulation tanks, and dry quenching coke exhaust gases. The purified waste gas, after separating ammonia and sulfides, is piped to a mixing chamber before entering the incineration unit. This method optimizes and integrates waste gas treatment methods in coking, metallurgy, and coal industrial production areas, combining absorption and adsorption methods to ensure purification efficiency. However, the VOCs waste gas is ultimately incinerated without being recovered for resource utilization.

[0005] CN109647126A discloses a method for purifying coking waste gas. The method involves the coking waste gas entering a buffer tank, undergoing coarse filtration, and then entering a two-stage adsorption device to adsorb acidic gases and VOCs in the coking waste gas. The purified gas is then discharged into the atmosphere. After the adsorption is saturated, the adsorption tower enters a regeneration process. The gas concentrated from the regeneration is cooled and then collected in a storage tank. This technical solution solves the problems of activated carbon adsorbing only a single type of gas and being unable to withstand high temperatures.

[0006] CN108607352A discloses a coking chemical product tail gas purification system, which recovers useful substances from the tail gas through a recovery unit and purifies the recovered tail gas through a purification unit, thereby achieving efficient resource utilization. However, this process includes a micro-nano bubble washing unit, a UV photocatalytic oxidation device, and an adsorption tower, making the process relatively complex and costly.

[0007] CN108283821A discloses a treatment process for naphthalene-containing waste gas in the chemical production section of coking plants. By using a coolant in the condensation step, naphthalene is separated and removed from the waste gas and then recovered. This solves the problem of the impact of naphthalene in the waste gas on subsequent equipment, and the naphthalene can be recovered through purging, effectively increasing the added value of the enterprise's production. However, the waste gas adsorption treatment in this process uses activated carbon adsorption and coke particle adsorption, which have limited adsorption efficiency.

[0008] In summary, current VOCs purification methods mostly employ combustion as the final treatment, which destructively purifies pollutants, wastes resources of recyclable waste gas, and poses significant safety risks when the area is an explosion-proof zone. On the other hand, current VOCs adsorption methods primarily use activated carbon as the adsorbent, but at high water content levels, water competition for adsorption is severe, resulting in limited adsorption capacity and removal rate. Therefore, there is a need for a safe, reliable, and economically feasible process and method for treating low-concentration, high-water-content VOCs. Summary of the Invention

[0009] The purpose of this invention is to provide a VOCs adsorption, condensation and recovery device system and method, which can achieve VOCs-containing flue gas emission in compliance with standards and efficiently and cost-effectively recover VOCs.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a VOCs adsorption-condensation-recovery device system, the VOCs adsorption-condensation-recovery device system comprising: a filtration device, an adsorption unit, a nitrogen storage device, a heating device, a condensation unit, and a chimney;

[0012] The filtration device is connected to the adsorption unit; the adsorption unit, the nitrogen storage device, the heating device, and the condensation unit form a circulation loop; the chimney is connected to the condensation unit.

[0013] The VOCs adsorption-condensation-recovery device system provided by this invention removes and recovers VOCs from flue gas. It has a simple structure, no secondary pollution, high safety, high processing efficiency, and low cost.

[0014] Preferably, the adsorption unit includes 2-8 adsorption boxes arranged in parallel, for example, 2, 3, 4, 5, 6, 7 or 8.

[0015] The number of adsorption boxes in the adsorption unit can be flexibly adjusted according to the actual flue gas volume.

[0016] Preferably, the adsorption material of the adsorption unit includes a combination of hydrophobic molecular sieve and Ag ion exchange molecular sieve.

[0017] Preferably, the hydrophobic molecular sieve comprises ZSM-5 and / or USY.

[0018] Preferably, the Ag ion exchange molecular sieve includes Ag / ZSM-5 and / or Ag / USY.

[0019] In existing technologies, activated carbon is generally selected as the adsorbent material. However, under high water content (water volume fraction > 3%) VOCs, the VOCs adsorption capacity is almost zero due to competitive adsorption by water. If hydrophobic molecular sieves are used, the molecular sieve channels are occupied by water due to competitive adsorption, especially the micropores are completely covered by water, which cannot effectively adsorb small molecule VOCs, causing small molecule VOCs to escape. The adsorption capacity drops significantly, and the decrease in adsorption capacity can reach 40% when the water content exceeds 4.5%. In contrast, Ag ions in Ag ion exchange molecular sieves have an inhibitory effect on the competitive adsorption of water and can provide adsorption sites for the adsorption of small molecule VOCs. In this invention, a combination of hydrophobic molecular sieve and Ag ion exchange molecular sieve is used. The adsorbent in the molecular sieve is aluminosilicate with a high silica-to-alumina ratio and is modified by Ag ion exchange. This enables synergistic adsorption of multi-component VOCs, reduces competitive adsorption between water and VOCs, and increases the adsorption capacity to over 50 mg / g. This avoids the disadvantages of conventional activated carbon, such as easy reduction of adsorption activity and flammability due to high-temperature desorption.

[0020] Preferably, the volume ratio of the hydrophobic molecular sieve to the Ag ion exchange molecular sieve is (2-4):1, for example, it can be 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, but is not limited to the listed values. Values ​​not listed within the range are also applicable.

[0021] As a preferred technical solution of the present invention, in any adsorption box, hydrophobic molecular sieves are arranged in front and Ag exchange molecular sieves are arranged behind, according to the flow direction of VOCs flue gas.

[0022] Preferably, the Ag ion exchange molecular sieve contains 1-20 wt% Ag by mass percentage, for example, 1 wt%, 5 wt%, 10 wt%, 15 wt%, or 20 wt%, but is not limited to the listed values. Values ​​not listed within the range are also applicable.

[0023] Preferably, the preparation method of the Ag ion-exchange molecular sieve includes the following steps:

[0024] (a) A mixture of ammonium source solution and hydrophobic molecular sieve is used to obtain an ammonium ion exchange molecular sieve;

[0025] (b) Silver nitrate and the ammonium ion exchange molecular sieve obtained in step (a) were mixed under microwave irradiation and then calcined to obtain Ag ion exchange molecular sieve.

[0026] Preparing Ag ion-exchange molecular sieves with high Ag loading using conventional liquid-phase ion exchange or impregnation methods can lead to pore blockage and reduced specific surface area, resulting in decreased adsorption capacity. In this invention, Ag ion-exchange molecular sieves are prepared using microwave-assisted hydrothermal exchange. By inputting energy with microwaves, the ion conversion frequency is increased, thereby increasing the ion exchange capacity and achieving high Ag content substitution.

[0027] Preferably, the hydrophobic molecular sieve in step (a) includes ZSM-5 and / or USY.

[0028] Preferably, the ammonium source in step (a) includes any one or a combination of at least two of ammonium chloride, ammonium nitrate, ammonia, ammonium carbonate, ammonium bicarbonate, ammonium sulfate, or ammonium bisulfate. Typical but non-limiting combinations include a combination of ammonium chloride and ammonium nitrate, a combination of ammonia and ammonium carbonate, a combination of ammonium bicarbonate, ammonium sulfate, and ammonium bisulfate, or a combination of ammonium chloride, ammonium nitrate, ammonia, and ammonium carbonate.

[0029] Preferably, the concentration of the ammonium source solution in step (a) is 0.1-1 mol / L based on ammonium ions, for example, it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L, but is not limited to the listed values, and values ​​not listed within the range are also applicable.

[0030] Preferably, the solid-liquid ratio in step (a) is (27-5400):1, for example, it can be 27:1, 1000:1, 2000:1, 3000:1, 4000:1 or 5400:1, but is not limited to the listed values. Values ​​not listed within the range are also applicable. The unit of the solid-liquid ratio is g / L.

[0031] Preferably, the mixing temperature in step (a) is 60-80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C, but is not limited to the listed values. Values ​​not listed within the range are also applicable.

[0032] Preferably, the mixing time in step (a) is 3-5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but not limited to the listed values. Values ​​not listed within the range are also applicable.

[0033] Preferably, after mixing in step (a), the mixture is subjected to a first filtration, a first washing, and a first drying in sequence.

[0034] Preferably, the first washing is performed 4-8 times, for example, 4, 5, 6, 7 or 8 times.

[0035] Preferably, the temperature of the first drying is 100-140°C, for example, it can be 100°C, 110°C, 120°C, 130°C or 140°C, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0036] Preferably, the first drying time is 10-14 hours, for example, it can be 10 hours, 11 hours, 12 hours, 13 hours or 14 hours, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0037] Preferably, the molar ratio of silver nitrate to ammonium ions in the ammonium ion exchange molecular sieve in step (b) is (1.8-2.2):1, for example, it can be 1.8:1, 1.9:1, 2:1, 2.1:1 or 2.2:1, but is not limited to the listed values. Values ​​not listed within the range are also applicable.

[0038] Preferably, the radiation power of the microwave in step (b) is 435W-570W, for example, it can be 435W, 450W, 480W, 500W, 520W, 550W or 570W, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0039] Preferably, the mixing time in step (b) is 5-9 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes or 9 minutes, but not limited to the listed values. Values ​​not listed within the range are also applicable.

[0040] Preferably, after mixing in step (b), the mixture is subjected to a second filtration, a second washing, and a second drying in sequence.

[0041] Preferably, the second washing is performed 4-8 times, for example, 4, 5, 6, 7 or 8 times.

[0042] Preferably, the temperature of the second drying is 100-140°C, for example, it can be 100°C, 110°C, 120°C, 130°C or 140°C, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0043] Preferably, the second drying time is 10-14 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours or 14 hours, but is not limited to the listed values. Values ​​not listed within the range are also applicable.

[0044] Preferably, the roasting temperature in step (b) is 300-400℃, for example, it can be 300℃, 320℃, 340℃, 360℃, 380℃ or 400℃, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0045] Preferably, the roasting time in step (b) is 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours or 3 hours, but not limited to the listed values. Values ​​not listed within the range are also applicable.

[0046] In solution, the ion exchange reaction rate of molecular sieves is constrained by the diffusion rate of exchange ions. Cations exist in a hydrated state in aqueous solution. Only when the diameter of the hydrated cation is smaller than the pore diameter of the molecular sieve can the exchange cation enter the molecular sieve and exchange with sodium ions. When the diameter of the hydrated cation is larger than the pore diameter, some coordinated water molecules must first be removed before the exchange ions can enter the molecular sieve to complete the ion exchange. In this invention, based on the anion diameter and the molecular sieve pore size, the parameters of the hydrothermal reaction for anion exchange are optimized. This allows water molecules to absorb appropriate microwave energy and then detach some of the water molecules coordinated with the cations, thus making it easier for them to enter the inner cage of the molecular sieve for ion exchange and increasing the ion exchange capacity.

[0047] Preferably, the heating temperature of the heating device is 200-350℃, for example, it can be 200℃, 220℃, 250℃, 280℃, 300℃, 320℃ or 350℃, but is not limited to the listed values, and values ​​not listed in the range are also applicable.

[0048] Preferably, the condensation unit includes at least three condensers arranged in series.

[0049] Preferably, the refrigerant in the secondary or higher condensers of the condensing unit includes an aqueous solution of ethylene glycol.

[0050] Preferably, the target condensation temperature of the condensation unit is ≤-30℃, for example, it can be -30℃, -35℃, -40℃, -45℃ or -50℃, but is not limited to the listed values, and values ​​not listed within the range are also applicable.

[0051] In this invention, after the VOCs flue gas passes through the first-stage condenser, the water vapor in it condenses, which removes the moisture from the flue gas. The temperature of the second-stage condenser is further reduced, which condenses the high-carbon hydrocarbons with a carbon number of 12 or more in the flue gas. Then, after passing through the third-stage or higher condenser, the low-carbon hydrocarbons in the flue gas are further condensed.

[0052] More preferably, the three-stage condenser of the condensing unit includes a precooler, a mechanical refrigeration unit, and a deep cooler in sequence.

[0053] Secondly, the present invention provides a method for recovering VOCs from a VOCs adsorption-condensation recovery device system as described in the first aspect, the recovery method comprising the following steps:

[0054] (1) After VOCs flue gas is collected, impurities are filtered through a filtration device and then enter the adsorption unit. The flue gas adsorbed by the adsorption unit is discharged through the chimney.

[0055] (2) The nitrogen in the nitrogen storage device is heated to 200-350℃ by the heating device and then enters the adsorption unit to desorb and carry out the VOCs flue gas adsorbed in the adsorption unit.

[0056] (4) The desorbed gas enters the condensation unit, and the VOCs in the gas are recovered through multi-stage condensation.

[0057] (5) After the condensed gas is heated by the heating device, it re-enters the adsorption unit for desorption until all VOCs in the adsorption unit are desorbed and condensed.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The VOCs adsorption, condensation, and recovery device system and method provided by this invention can recover low VOCs concentrations (≤100 mg / m³). 3 It can remove and recover VOCs from flue gas with high moisture content (greater than 3%), with a VOCs removal rate of over 92.1%, especially over 97.8%, and a recovery rate of over 97%. It uses a small amount of adsorbent, has high treatment efficiency, low cost, high safety, and no secondary pollution. Attached Figure Description

[0060] Figure 1 This is a structural diagram of the VOCs adsorption, condensation, and recovery device system provided in Embodiment 1 of the present invention;

[0061] Among them, 1 is a filtration device; 2.1 is a first adsorption box; 2.2 is a second adsorption box; 3 is a nitrogen storage device; 4 is a heating device; 5 is a primary condenser; 6 is a secondary condenser; 7 is a tertiary condenser; and 8 is a chimney. Detailed Implementation

[0062] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0063] To clearly illustrate the technical solution of the present invention, the VOCs concentration in the flue gas is measured at the airflow inlet and airflow outlet of the adsorption unit of the VOCs adsorption condensation recovery device system in the embodiment of the present invention, and the VOCs removal rate is calculated; the amount of VOCs recovered in the condensation unit is measured, and the ratio of the recovered amount to the amount of VOCs adsorbed is calculated as the VOCs recovery rate.

[0064] Preparation Example 1

[0065] This preparation example provides a method for preparing Ag ion-exchange molecular sieves, the method comprising the following steps:

[0066] (a) A 0.1 mol / L ammonium chloride solution was mixed with ZSM-5 molecular sieve at a solid-liquid ratio of 27:1 g / L. After ion exchange in a hydrothermal reactor at 70℃ for 4 h, the mixture was filtered and washed 6 times and dried at 120℃ for 12 h to obtain ammonium ion exchange molecular sieve.

[0067] (b) A silver nitrate solution and the ammonium ion-exchange molecular sieve obtained in step (a) were mixed at a molar ratio of silver nitrate to ammonium of 2:1. After ion exchange for 8 min under a radiation power of 440 W, the mixture was filtered and washed 6 times, dried at 120 °C for 12 h, and then calcined at 350 °C for 2 h.

[0068] The Ag loading of the Ag ion exchange molecular sieve obtained in this preparation example is 20 wt%.

[0069] Preparation Example 2

[0070] This preparation example provides a method for preparing Ag ion-exchange molecular sieves, the method comprising the following steps:

[0071] (a) A 1 mol / L ammonium chloride solution was mixed with ZSM-5 molecular sieve at a solid-liquid ratio of 540:1 g / L. After ion exchange in a hydrothermal reactor at 60℃ for 5 h, the mixture was filtered and washed 4 times and dried at 100℃ for 14 h to obtain ammonium ion exchange molecular sieve.

[0072] (b) A silver nitrate solution and the ammonium ion-exchange molecular sieve obtained in step (a) were mixed at a molar ratio of silver nitrate to ammonium of 1.8:1. After ion exchange for 7 min under a radiation power of 445 W, the mixture was filtered and washed 4 times, dried at 100 °C for 14 h, and then calcined at 300 °C for 3 h.

[0073] The Ag loading of the Ag ion exchange molecular sieve obtained in this preparation example is 10 wt%.

[0074] Preparation Example 3

[0075] This preparation example provides a method for preparing Ag ion-exchange molecular sieves, the method comprising the following steps:

[0076] (a) A 1 mol / L ammonium chloride solution was mixed with ZSM-5 molecular sieve at a solid-liquid ratio of 5400:1 g / L. After ion exchange in a hydrothermal reactor at 80℃ for 3 h, the mixture was filtered and washed 8 times and dried at 140℃ for 10 h to obtain ammonium ion exchange molecular sieve.

[0077] (b) A silver nitrate solution and the ammonium ion-exchange molecular sieve obtained in step (a) were mixed at a molar ratio of silver nitrate to ammonium of 2.2:1. After ion exchange for 8 min under a radiation power of 435 W, the mixture was filtered and washed 8 times, dried at 140 °C for 10 h, and then calcined at 400 °C for 1 h.

[0078] The Ag loading of the Ag ion exchange molecular sieve obtained in this preparation example is 1 wt%.

[0079] Preparation Example 4

[0080] This preparation example provides a method for preparing Ag ion-exchange molecular sieves, the method comprising the following steps:

[0081] (a) A 0.5 mol / L ammonium chloride solution was mixed with USY molecular sieve at a solid-liquid ratio of 270 g / L. After ion exchange in a hydrothermal reactor at 70°C for 4 h, the mixture was filtered and washed 6 times and dried at 120°C for 12 h to obtain ammonium ion exchange molecular sieve.

[0082] (b) A silver nitrate solution and the ammonium ion-exchange molecular sieve obtained in step (a) were mixed at a molar ratio of silver nitrate to ammonium of 2:1. After ion exchange for 9 min under a radiation power of 570 W, the mixture was filtered and washed 6 times, dried at 120 °C for 12 h, and then calcined at 350 °C for 2 h.

[0083] The Ag loading of the Ag ion exchange molecular sieve obtained in this preparation example is 10 wt%.

[0084] Preparation Example 5

[0085] This preparation example provides a method for preparing Ag ion-exchange molecular sieves. Compared with preparation example 1, the molar ratio of silver nitrate to ammonium in step (b) is 0.5:1, and the rest is the same as in example 1.

[0086] Preparation Example 6

[0087] This preparation example provides a method for preparing Ag ion-exchange molecular sieves. Compared with preparation example 1, the molar ratio of silver nitrate to ammonium in step (b) is 4:1, and the rest is the same as in example 1.

[0088] Preparation Example 7

[0089] This preparation example provides a method for preparing Ag ion exchange molecular sieves. Compared with preparation example 1, the microwave radiation power in step (b) is 350W, and the rest is the same as in example 1.

[0090] Preparation Example 8

[0091] This preparation example provides a method for preparing Ag ion exchange molecular sieves. Compared with preparation example 1, the microwave radiation power in step (b) is 650W, and the rest is the same as in example 1.

[0092] Preparation Example 9

[0093] This preparation example provides a method for preparing Ag ion-exchange molecular sieves. Compared with preparation example 1, the ion exchange time in step (b) is 3 min, and the rest is the same as in example 1.

[0094] Preparation Example 10

[0095] This preparation example provides a method for preparing Ag ion-exchange molecular sieves. Compared with preparation example 1, the ion exchange time in step (b) is 12 min, and the rest is the same as in example 1.

[0096] Example 1

[0097] This embodiment provides a VOCs adsorption, condensation, and recovery device system, such as... Figure 1 As shown, the VOCs adsorption-condensation-recovery device system includes: a filter device 1, an adsorption unit, a nitrogen storage device 3, a heating device 4, a condensation unit, and a chimney 8; the filter device 1 is connected to the adsorption unit; the adsorption unit, the nitrogen storage device 3, the heating device 4, and the condensation unit form a circulation loop; the chimney 8 is connected to the condensation unit.

[0098] The adsorption unit comprises two adsorption chambers connected in parallel: a first adsorption chamber 2.1 and a second adsorption chamber 2.2. The adsorbent material in the adsorption chamber is a combination of ZSM-5 and Ag / ZSM-5, where Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 1, and the volume ratio of ZSM-5 to Ag / ZSM-5 is 2:1. Following the VOCs flue gas flow direction, the hydrophobic molecular sieve is placed first, followed by the Ag ion exchange molecular sieve, and the adsorbent breakthrough adsorption capacity is 50 mg / g. The condensation unit comprises three condensers connected in series: a first-stage condenser 5, a second-stage condenser 6, and a third-stage condenser 7. The refrigerant in the second-stage and third-stage condensers is a 50% ethylene glycol aqueous solution.

[0099] Example 2

[0100] This embodiment provides a VOCs adsorption-condensation-recovery device system, which includes: a filtration device, an adsorption unit, a nitrogen storage device, a heating device, a condensation unit, and a chimney; the filtration device is connected to the adsorption unit; the adsorption unit, the nitrogen storage device, the heating device, and the condensation unit form a circulation loop; and the chimney is connected to the condensation unit.

[0101] The adsorption unit comprises five adsorption chambers connected in parallel: a first adsorption chamber, a second adsorption chamber, a third adsorption chamber, a fourth adsorption chamber, and a fifth adsorption chamber. The adsorbent material in each adsorption chamber is a combination of ZSM and Ag / ZSM-5, where Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 2, with a volume ratio of ZSM-5 to Ag / ZSM-5 of 2:1. Following the VOCs flue gas flow direction, the hydrophobic molecular sieve is positioned first, followed by the Ag ion exchange molecular sieve, and the adsorbent breakthrough adsorption capacity is 50 mg / g. The condensation unit comprises three condensers connected in series: a first-stage condenser, a second-stage condenser, and a third-stage condenser. The refrigerant in the second-stage and third-stage condensers is a 50% ethylene glycol aqueous solution.

[0102] Example 3

[0103] This embodiment provides a VOCs adsorption-condensation-recovery device system, which includes: a filtration device, an adsorption unit, a nitrogen storage device, a heating device, a condensation unit, and a chimney; the filtration device is connected to the adsorption unit; the adsorption unit, the nitrogen storage device, the heating device, and the condensation unit form a circulation loop; and the chimney is connected to the condensation unit.

[0104] The adsorption unit comprises eight adsorption chambers connected in parallel: a first adsorption chamber, a second adsorption chamber, a third adsorption chamber, a fourth adsorption chamber, a fifth adsorption chamber, a sixth adsorption chamber, a seventh adsorption chamber, and an eighth adsorption chamber. The adsorbent material in each adsorption chamber is a combination of ZSM and Ag / ZSM-5, where Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 3, with a volume ratio of ZSM-5 to Ag / ZSM-5 of 2:1. Following the VOCs flue gas flow direction, the hydrophobic molecular sieve is positioned first, followed by the Ag ion exchange molecular sieve, and the adsorbent breakthrough adsorption capacity is 50 mg / g. The condensation unit comprises three condensers connected in series: a first-stage condenser, a second-stage condenser, and a third-stage condenser. The refrigerant in the second-stage and third-stage condensers is a 50% ethylene glycol aqueous solution.

[0105] Example 4

[0106] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, the adsorption material in the adsorption box is a combination of USY and Ag / USY. Ag / USY is the Ag / USY molecular sieve prepared in Preparation Example 4. All other aspects are the same as in Example 1.

[0107] Example 5

[0108] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 5, and the rest are the same as in Example 1.

[0109] Example 6

[0110] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, the Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 6, and the rest are the same as in Example 1.

[0111] Example 7

[0112] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, the Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 7, and the rest are the same as in Example 1.

[0113] Example 8

[0114] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, the Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 8, and the rest are the same as in Example 1.

[0115] Example 9

[0116] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, the Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 9, and the rest are the same as in Example 1.

[0117] Example 10

[0118] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Example 1, Ag / ZSM-5 is the Ag / ZSM-5 molecular sieve prepared in Preparation Example 10, and the rest are the same as in Example 1.

[0119] Example 11

[0120] This embodiment provides a VOCs adsorption condensation recovery device system. Compared with Embodiment 1, the volume ratio of ZSM-5 and Ag / ZSM-5 is 3:1, and all other aspects are the same as in Embodiment 1.

[0121] Example 12

[0122] This embodiment provides a VOCs adsorption condensation recovery device system. Compared with Embodiment 1, the volume ratio of ZSM-5 and Ag / ZSM-5 is 4:1, and all other aspects are the same as in Embodiment 1.

[0123] Example 13

[0124] This embodiment provides a VOCs adsorption condensation recovery device system. Compared with Embodiment 1, the volume ratio of ZSM-5 and Ag / ZSM-5 is 6:1, and all other aspects are the same as in Embodiment 1.

[0125] Example 14

[0126] This embodiment provides a VOCs adsorption, condensation and recovery device system. Compared with Embodiment 1, the adsorption material in the adsorption box is ZSM-5, and the rest is the same as in Embodiment 1.

[0127] Application Example 1

[0128] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Embodiment 1 of the present invention. The recovery method includes the following steps:

[0129] (1) The water content is 4.5% and the VOCs concentration is 60 mg / m³. 3 After VOCs flue gas is collected, it is processed at a flow rate of 50m³. 3 After impurities are filtered out by the filter device, the flue gas enters the first adsorption box. After being adsorbed by the first adsorption box, the flue gas is heat-exchanged by the first-stage condenser and then discharged through the chimney.

[0130] (2) After the first adsorption box reaches saturation, the VOCs flue gas is switched to the second adsorption box for adsorption.

[0131] (3) The nitrogen storage device releases nitrogen, which is heated to 200°C by the heating device and then enters the first adsorption box to desorb and carry out the VOCs adsorbed in the first adsorption box.

[0132] (4) The gas after analysis is condensed and recovered from VOCs by passing through a first-stage condenser, a second-stage condenser, and a third-stage condenser in sequence; the temperature of the first-stage condenser is 0℃, the temperature of the second-stage condenser is -15℃, and the temperature of the third-stage condenser is -32℃.

[0133] (5) After the condensed gas is heated by the heating device, it re-enters the first adsorption box for desorption until all VOCs in the first adsorption box are desorbed and condensed.

[0134] In this application example, the VOCs removal rate and recovery rate results are listed in Table 1.

[0135] Application Example 2

[0136] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Embodiment 2 of the present invention. The recovery method includes the following steps:

[0137] (1) The water content is 4.5% and the VOCs concentration is 60 mg / m³.3 After VOCs flue gas is collected, it is processed at a flow rate of 50m³. 3 After impurities are filtered out by the filter device, the flue gas enters the first adsorption box. After being adsorbed by the first adsorption box, the flue gas is heat-exchanged by the first-stage condenser and then discharged through the chimney.

[0138] (2) After the first adsorption box reaches saturation, the VOCs flue gas is switched to the second adsorption box for adsorption.

[0139] (3) The nitrogen storage device releases nitrogen, which is heated to 300°C by the heating device and then enters the first adsorption box to desorb and carry out the VOCs adsorbed in the first adsorption box.

[0140] (4) The gas after analysis is condensed and recovered from VOCs by passing through a first-stage condenser, a second-stage condenser, and a third-stage condenser in sequence; the temperature of the first-stage condenser is 0℃, the temperature of the second-stage condenser is -15℃, and the temperature of the third-stage condenser is -32℃.

[0141] (5) After the condensed gas is heated by the heating device, it re-enters the first adsorption box for desorption until all VOCs in the first adsorption box are desorbed and condensed.

[0142] (6) After the second adsorption box reaches saturation, the VOCs flue gas is switched to the third adsorption box for adsorption, and the desorption and condensation process of steps (3) to (5) is repeated for the second adsorption box. This step is repeated from the third adsorption box to the fifth adsorption box.

[0143] In this application example, the VOCs removal rate and recovery rate results are listed in Table 1.

[0144] Application Example 3

[0145] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Embodiment 3 of the present invention. The recovery method includes the following steps:

[0146] (1) The water content is 4.5% and the VOCs concentration is 60 mg / m³. 3 After VOCs flue gas is collected, it is processed at a flow rate of 50m³. 3 After impurities are filtered out by the filter device, the flue gas enters the first adsorption box. After being adsorbed by the first adsorption box, the flue gas is heat-exchanged by the first-stage condenser and then discharged through the chimney.

[0147] (2) After the first adsorption box reaches saturation, the VOCs flue gas is switched to the second adsorption box for adsorption.

[0148] (3) The nitrogen storage device releases nitrogen gas, which is heated to 350°C by the heating device and then enters the first adsorption box to desorb and carry out the VOCs adsorbed in the first adsorption box.

[0149] (4) The gas after analysis is condensed and recovered from VOCs by passing through a first-stage condenser, a second-stage condenser, and a third-stage condenser in sequence; the temperature of the first-stage condenser is 0℃, the temperature of the second-stage condenser is -15℃, and the temperature of the third-stage condenser is -32℃.

[0150] (5) After the condensed gas is heated by the heating device, it re-enters the first adsorption box for desorption until all VOCs in the first adsorption box are desorbed and condensed.

[0151] (6) After the second adsorption box reaches saturation, the VOCs flue gas is switched to the third adsorption box for adsorption, and the desorption and condensation process from step (3) to step (5) is repeated for the second adsorption box. This step is repeated from the third adsorption box to the eighth adsorption box.

[0152] In this application example, the VOCs removal rate and recovery rate results are listed in Table 1.

[0153] Application Example 4

[0154] This application example provides a method for recovering VOCs using the VOCs adsorption condensation recovery device system provided in Example 4 of the present invention. Compared with Application Example 1, nitrogen is heated to 350°C in step (3), and the rest is the same as Application Example 1.

[0155] Application Example 5

[0156] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 5 of the present invention. The recovery method is the same as that in Application Example 1.

[0157] Application Example 6

[0158] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 6 of the present invention. The recovery method is the same as that in Application Example 1.

[0159] Application Example 7

[0160] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 7 of the present invention. The recovery method is the same as that in Application Example 1.

[0161] Application Example 8

[0162] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 8 of the present invention. The recovery method is the same as that in Application Example 1.

[0163] Application Example 9

[0164] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 9 of the present invention. The recovery method is the same as that in Application Example 1.

[0165] Application Example 10

[0166] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 10 of the present invention. The recovery method is the same as that in Application Example 1.

[0167] Application Example 11

[0168] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 11 of the present invention. The recovery method is the same as that in Application Example 1.

[0169] Application Example 12

[0170] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 12 of the present invention. The recovery method is the same as that in Application Example 1.

[0171] Application Example 13

[0172] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 13 of the present invention. The recovery method is the same as that in Application Example 1.

[0173] Application Example 14

[0174] This application example provides a method for recovering VOCs using the VOCs adsorption-condensation recovery device system provided in Example 14 of the present invention. The recovery method is the same as that in Application Example 1.

[0175] Application Example 15

[0176] This application example provides a method for recovering VOCs using the VOCs adsorption condensation recovery device system provided in Example 1 of the present invention. Compared with Application Example 1, in step (3), nitrogen is heated to 150°C, and the rest are the same as in Application Example 1.

[0177] Table 1

[0178]

[0179]

[0180] The following points can be drawn from Table 1:

[0181] (1) As can be seen from Application Examples 1-4 and Application Examples 11-12, the device system and method provided by the present invention can effectively remove VOCs from flue gas with a removal rate of over 97.8% and a good removal effect.

[0182] (2) Compared with Application Example 1, the amount of silver nitrate used in the preparation of Ag ion exchange molecular sieve in Application Example 5 was lower, resulting in a lower Ag loading in the prepared molecular sieve, which led to a decrease in the adsorption effect on VOCs and a decrease in the VOCs removal rate; In Application Example 6, the amount of silver nitrate used in the preparation of Ag ion exchange molecular sieve was higher. Due to the limitation of the number of ion exchange sites, too many Ag ions could not be loaded on the exchange sites and were located in the molecular sieve channels, causing channel blockage and a decrease in specific surface area, thereby reducing the adsorption effect on VOCs and a decrease in the VOCs removal rate; In Application Examples 7 and 8, the preparation of Ag ion exchange molecular sieves... If the microwave radiation power is too low or too high during the preparation of Ag ion exchange molecular sieves, it will be difficult for Ag ions to complex, thus reducing the loading. At the same time, the loaded Ag will not be at the ion exchange sites, but in the molecular sieve channels, causing channel blockage, reducing the specific surface area, and reducing the VOCs removal rate. In application example 9, if the reaction time is too short during the preparation of Ag ion exchange molecular sieves, it will lead to a decrease in Ag loading and a decrease in VOCs removal rate. In application example 10, if the reaction time is too long during the preparation of Ag ion exchange molecular sieves, it will lead to excessive silver deposition on the surface of the molecular sieve, resulting in a decrease in specific surface area and a decrease in VOCs removal rate.

[0183] (3) Compared with Application Example 1, in Application Example 13, the amount of Ag ion exchange molecular sieve used is smaller, and the adsorption of small molecule VOCs may be incomplete, resulting in a decrease in the removal rate of VOCs; in Application Example 14, Ag ion exchange molecular sieve is not used, and small molecule VOCs cannot be effectively adsorbed, causing small molecule VOCs to escape, resulting in a low removal rate of VOCs.

[0184] (4) Application Examples 1-14 can all achieve effective recovery of VOCs with a recovery rate of over 97.0%. Compared with Application Example 1, the heating temperature of Application Example 15 is lower, making it difficult to achieve complete desorption of VOCs adsorbed by molecular sieves, thus reducing the VOCs recovery rate. The heating temperature in Application Examples 3-4 reaches 350℃, and the VOCs recovery rate is over 99.1%, with good recovery effect. If the heating temperature is too high, it is difficult to further improve the recovery rate, consume too much energy, and affect the safety of the device.

[0185] Therefore, the preferred device system and recycling method of this invention can effectively achieve the removal and recycling of VOCs.

[0186] In summary, the VOCs adsorption, condensation, and recovery device system and method provided by this invention can recover low VOCs concentrations (≤100 mg / m³). 3It can remove and recover VOCs from flue gas with high moisture content (greater than 3%), with a VOCs removal rate of over 92.1%, especially over 97.8%, and a recovery rate of over 97%. It uses a small amount of adsorbent, has high treatment efficiency, low cost, high safety, and no secondary pollution.

[0187] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A VOCs adsorption condensation recovery device system, characterized in that, The VOCs adsorption-condensation-recovery system includes: a filtration device, an adsorption unit, a nitrogen storage device, a heating device, a condensation unit, and a chimney; The filtration device is connected to the adsorption unit; The adsorption unit, nitrogen storage device, heating device, and condensation unit form a circulation loop; the chimney is connected to the condensation unit. The adsorption material of the adsorption unit includes a combination of hydrophobic molecular sieves and Ag ion exchange molecular sieves. In any adsorption chamber of the adsorption unit, the hydrophobic molecular sieve is placed in front and the Ag ion exchange molecular sieve is placed behind, according to the VOCs flue gas flow direction. The volume ratio of the hydrophobic molecular sieve to the Ag ion exchange molecular sieve is (2-4):

1. The hydrophobic molecular sieve includes ZSM-5 and / or USY, and the Ag ion exchange molecular sieve includes Ag / ZSM-5 and / or Ag / USY. In the Ag ion exchange molecular sieve, the Ag content, by mass percentage, is 1-20 wt%. The Ag ion-exchange molecular sieve is prepared using the following method: Step (a) Mix the ammonium source solution with the hydrophobic molecular sieve to obtain an ammonium ion exchange molecular sieve; In step (b), silver nitrate and the ammonium ion exchange molecular sieve obtained in step (a) are mixed under microwave irradiation with a radiation power of 435-570W, and Ag ion exchange molecular sieve is obtained after calcination.

2. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The adsorption unit comprises 2-8 adsorption boxes arranged in parallel.

3. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The ammonium source in step (a) includes any one or a combination of at least two of ammonium chloride, ammonium nitrate, ammonia, ammonium carbonate, ammonium bicarbonate, ammonium sulfate, or ammonium bisulfate.

4. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The concentration of the ammonium source solution in step (a) is 0.1-1 mol / L, calculated as ammonium ions.

5. The VOCs adsorption-condensation-recovery device system according to claim 1, characterized in that, The solid-liquid ratio of the mixture in step (a) is (27-5400):1, and the unit of the solid-liquid ratio is g / L.

6. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The mixing temperature in step (a) is 60-80°C.

7. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The mixing time in step (a) is 3-5 hours.

8. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The molar ratio of silver nitrate to ammonium ions in the ammonium ion exchange molecular sieve in step (b) is (1.8-2.2):

1.

9. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The mixing time in step (b) is 5-9 minutes.

10. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The roasting temperature in step (b) is 300-400℃.

11. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The roasting time in step (b) is 1-3 hours.

12. The VOCs adsorption-condensation-recovery device system according to claim 1, characterized in that, The heating temperature of the heating device is 200-350℃.

13. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The condensation unit includes at least three stages of condensers arranged in series.

14. The VOCs adsorption condensation recovery device system of claim 13, wherein, The refrigerant in the secondary and higher condensers of the condensing unit includes an aqueous solution of ethylene glycol.

15. The VOCs adsorption condensation recovery device system according to claim 1, wherein, The target condensation temperature of the condensation unit is ≤-30℃.

16. A method for recovering VOCs using the VOCs adsorption condensation recovery device system according to any one of claims 1-15, characterized in that, The recycling method includes the following steps: (1) After VOCs flue gas is collected, impurities are filtered by a filtration device and then enter the adsorption unit. The flue gas adsorbed by the adsorption unit is discharged through the chimney. (2) The nitrogen in the nitrogen storage device is heated to 200-350°C by the heating device and then enters the adsorption unit to desorb and carry out the VOCs flue gas adsorbed in the adsorption unit. (3) The desorbed gas enters the condensation unit, and the VOCs in the gas are recovered through multi-stage condensation; (4) The condensed gas is heated by the heating device and re-enters the adsorption unit for desorption until all VOCs in the adsorption unit are desorbed and condensed.

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