Continuous regeneration process of saturated adsorption waste activated carbon

Abstract

The invention provides a continuous regeneration process of saturated adsorption waste activated carbon, and relates to the technical field of adsorbent recycling. The regeneration process comprises the following steps: sequentially carrying out cleaning, sieving, impurity removal and filter pressing on waste activated carbon to obtain pretreated waste activated carbon; carrying out drying treatment on the activated carbon, and then carrying out microwave regeneration to obtain activated and regenerated activated carbon; carrying out solid-liquid separation on tail gas generated in the drying process, recovering solids, carrying out microwave regeneration, and enabling gas to enter a tail gas treatment system; the tail gas generated in the microwave regeneration process is dedusted, and dust and dedusted tail gas are separated; the dust is regenerated activated carbon, and the dust-removed tail gas enters a tail gas treatment system; the tail gas treatment system comprises a first spray tower, a secondary combustion chamber, a quench tower, a bag-type dust collector and a second spray tower. The regeneration process is wide in application range, damage to the structure of the activated carbon is small, and the saturated adsorption capacity of the activated carbon is basically unchanged after five times of adsorption-regeneration cycles.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbent recovery and reuse, and in particular to a continuous regeneration process for saturated adsorption waste activated carbon. Background Art

[0002] Activated carbon has the characteristics of a well-developed pore structure, a large specific surface area, and a wide distribution of surface functional groups. It can effectively adsorb a variety of volatile organic compounds in the atmosphere and difficult-to-degrade pollutants in water, and is often used as an adsorbent in industrial wastewater treatment. Currently, waste activated carbon that has reached adsorption saturation is often treated and disposed of by regeneration, landfill, or incineration. Regeneration of waste activated carbon refers to the use of physical or chemical means to remove the adsorbed adsorbate while maintaining the original structure of the waste activated carbon, thereby restoring the pore structure within the activated carbon so that it can be reused for adsorption, thereby indirectly reducing the cost of using the activated carbon and achieving resource recycling.

[0003] Currently, the main activated carbon regeneration technologies used domestically and internationally include thermal regeneration, solvent regeneration, chemical regeneration, biological regeneration, and electrochemical regeneration. High-temperature thermal regeneration of spent activated carbon is the most mature and widely used regeneration method in industry. The regeneration process includes preheating, pyrolysis, and activation. Granular activated carbon is typically regenerated in a rotary kiln, while powdered activated carbon is typically regenerated in a fixed externally heated furnace. High-temperature thermal regeneration processes consume a lot of energy, require large equipment, and are difficult to miniaturize. Therefore, developing a convenient and efficient activated carbon regeneration process is of great scientific and practical significance.

[0004] CN119186539A discloses a method for regenerating activated carbon based on ultrasonic coupling. The invention places the activated carbon to be regenerated into a reaction vessel, adds a target alkaline solution, and places it in a temperature-controlled ultrasonic device for oscillation treatment; adjusts the pH of the solution in the reaction vessel and controls the uniform distribution of ultrasonic waves. After treatment, the solution is discharged and the reactants are rinsed to neutrality; the reactants are transferred to an acid-resistant reactor, and a preheated acidic solution is added, and placed in a dual-frequency ultrasonic device for oscillation treatment; the reactor is cooled and the stirring speed is adjusted. After monitoring the conductivity to a set value, the reactants are transferred, rinsed, and vacuum-dried to obtain regenerated activated carbon. The method provided by this invention has poor applicability. It cannot regenerate all types of waste activated carbon by relying solely on acid-base solutions and ultrasonic treatment, and the process operation is relatively cumbersome.

[0005] Microwave regeneration can directly provide energy to activated carbon. Unlike conventional heating, energy transfer occurs through conduction or convection, but rather through dipole rotation and ion conduction. This allows the energy to be easily converted into heat within the particles, achieving heating at the molecular level. This allows substances adsorbed on the activated carbon to overcome van der Waals forces, desorb, and burn, ultimately completely decomposing. This is an excellent method. However, the regeneration method provided by patent CN114225926A primarily regenerates saturated adsorbed granular activated carbon in an iodine adsorber. The equipment and process are relatively simple, and for tail gas collection, only alkali and acid solutions are provided. The tail gas treatment capacity is poor, as it only treats iodine impurities adsorbed in saturated adsorbed activated carbon and iodine-containing tail gas generated during the regeneration process. It is not applicable to all types of adsorbed activated carbon.

[0006] Based on the above problems, those skilled in the art are in urgent need of disclosing a regeneration process with low energy consumption, high efficiency and applicable to various types of saturated adsorption activated carbon. Summary of the Invention

[0007] The object of the present invention is to provide a continuous regeneration process for saturated adsorption waste activated carbon to solve the problem that the existing saturated adsorption activated carbon regeneration process cannot be applied to all types of waste activated carbon. In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a continuous regeneration process for saturated adsorption waste activated carbon, comprising the following steps:

[0009] 1) washing, screening, removing impurities and filtering the waste activated carbon in sequence to obtain pretreated waste activated carbon;

[0010] 2) drying the pretreated waste activated carbon to obtain dried waste activated carbon and dried tail gas;

[0011] 3) regenerating the dried waste activated carbon by microwave to obtain activated regenerated activated carbon and activated regenerated tail gas;

[0012] The dried tail gas is subjected to gas-solid separation to obtain separated tail gas and recovered activated carbon dust, the recovered activated carbon dust is mixed with the waste activated carbon dried in step 2) and subjected to microwave regeneration; the separated tail gas enters the tail gas treatment system;

[0013] The activated regenerated tail gas is subjected to dust removal to obtain activated carbon dust after activation and regeneration and dust-removed tail gas; the activated carbon dust after activation and regeneration is used as activated carbon after activation and regeneration; the dust-removed tail gas enters the tail gas treatment system;

[0014] The tail gas treatment system includes a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower which are arranged in sequence.

[0015] Preferably, the drying temperature in step 2) is 80-150°C;

[0016] The moisture content of the dried waste activated carbon is 5-10%.

[0017] Preferably, the particle size of the dried waste activated carbon in step 3) is 5 to 80 mesh and can be directly subjected to microwave regeneration;

[0018] When the particle size of the dried waste activated carbon is less than 80 meshes, it needs to be mixed with waste activated carbon with a particle size of 5 to 80 meshes and then subjected to microwave regeneration, and the mass ratio of the two is 1:2 to 10.

[0019] Preferably, the microwave regeneration temperature in step 3) is 500-850° C., and the time is 0.5-2 h.

[0020] Preferably, the atmosphere of the microwave regeneration is an oxygen-free atmosphere.

[0021] Preferably, the pressure of the microwave regeneration is 5 to 20 kPa.

[0022] Preferably, the first spray tower is an alkali solution spray tower;

[0023] The alkali solution is a sodium hydroxide solution with a pH value of 9-12.

[0024] Preferably, the combustion temperature of the secondary combustion chamber is 1000-1500°C.

[0025] Preferably, the second spray tower is a cooling and dust removal tower.

[0026] Preferably, the waste activated carbon includes waste activated carbon that adsorbs organic pollutants and / or waste activated carbon that adsorbs inorganic salt pollutants.

[0027] The present invention has at least the following beneficial effects:

[0028] The particle size ratio of the activated carbon product regenerated by the regeneration process of the present invention is basically unchanged from that of the unregenerated activated carbon, the mechanical properties are 99.2%, and there is basically no mechanical wear. After multiple cycles of treatment, the performance of the regenerated activated carbon product remains basically unchanged during 2 to 5 adsorption-regeneration cycles, indicating that the regenerated activated carbon product has excellent cycle performance.

[0029] The regeneration process of the present invention has a wide range of applications and can effectively treat saturated adsorption activated carbon that adsorbs different pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 These are photos of the spent activated carbon before and after regeneration in Example 1. Figure 1 (A) is a photo of waste activated carbon raw materials. Figure 1(B) is a photo of the waste activated carbon after washing, screening, impurity removal, filter pressing and drying. Figure 1 (C) is a photo of waste activated carbon after microwave regeneration. DETAILED DESCRIPTION

[0031] The present invention provides a continuous regeneration process for saturated adsorption waste activated carbon, comprising the following steps:

[0032] 1) washing, screening, removing impurities and filtering the waste activated carbon in sequence to obtain pretreated waste activated carbon;

[0033] 2) drying the pretreated waste activated carbon to obtain dried waste activated carbon and dried tail gas;

[0034] 3) regenerating the dried waste activated carbon by microwave to obtain activated regenerated activated carbon and activated regenerated tail gas;

[0035] The dried tail gas is subjected to gas-solid separation to obtain separated tail gas and recovered activated carbon dust, the recovered activated carbon dust is mixed with the waste activated carbon dried in step 3) and subjected to microwave regeneration; the separated tail gas enters the tail gas treatment system;

[0036] The activated and regenerated tail gas is subjected to dust removal to obtain activated carbon dust after activation and regeneration and dust-removed tail gas; the activated carbon dust after activation and regeneration is used as activated carbon after activation and regeneration; the dust-removed tail gas enters the tail gas treatment system.

[0037] In the present invention, the tail gas treatment system includes a first spray tower, a secondary combustion chamber, a quenching tower, a bag filter and a second spray tower which are arranged in sequence.

[0038] In the present invention, the drying temperature in step 2) is 80-150°C, preferably 90-140°C, more preferably 100-130°C, and even more preferably 110-120°C.

[0039] In the present invention, the drying method can be selected from microwave drying, hot air drying, and spray drying.

[0040] In the present invention, the dry atmosphere is an oxygen-free atmosphere.

[0041] The moisture content of the dried waste activated carbon is 5-10%, preferably 6-9%, and more preferably 7-8%.

[0042] In the present invention, the dried waste activated carbon in step 3) can be directly subjected to microwave regeneration when the particle size is 5 to 80 meshes.

[0043] In the present invention, when the particle size of the dried waste activated carbon is less than 80 mesh, it needs to be mixed with waste activated carbon with a particle size of 5 to 80 mesh and then subjected to microwave regeneration, and the mass ratio of the two is 1:2 to 10, preferably 1:4 to 9, further preferably 1:6 to 8, and more preferably 1:7; mixing activated carbon powder with smaller particle size with granular activated carbon with larger particle size and then subjecting to microwave regeneration can prevent a large amount of absolutely dry activated carbon powder from flying during the drying process (moisture content is 0%), and also prevent the waste activated carbon from raising too much dust during the regeneration process, resulting in a large loss of activated carbon.

[0044] In the present invention, the temperature of the microwave regeneration in step 3) is 500-850°C, preferably 550-800°C, more preferably 600-750°C, and more preferably 650-700°C; the time is 0.5-2h, preferably 0.75-1.75h, and more preferably 1-1.5h.

[0045] In the present invention, the atmosphere of the microwave regeneration is an oxygen-free atmosphere, preferably a nitrogen atmosphere or a water vapor atmosphere, to avoid oxidation of the activated carbon due to contact with oxygen during the regeneration process.

[0046] In the present invention, the pressure of the microwave regeneration is 5-20 kPa, preferably 8-18 kPa, more preferably 10-15 kPa, and more preferably 12-14 kPa. Maintaining a slightly positive pressure in the microwave regeneration furnace can prevent the entry of external air and the leakage of harmful gases.

[0047] In the present invention, the first spray tower is an alkali solution spray tower.

[0048] In the present invention, the alkali solution is a sodium hydroxide solution with a pH value of 9 to 12, preferably 9.5 to 11.5, and more preferably 10 to 11.

[0049] In the present invention, the combustion temperature of the secondary combustion chamber is 1000-1500°C, preferably 1100-1450°C, more preferably 1200-1400°C, and even more preferably 1300-1350°C. Ammonia is introduced into the secondary combustion chamber for desulfurization and denitrification.

[0050] In the present invention, the second spray tower is a cooling and dust removal tower, which uses alkaline solution for spraying to prevent the presence of incompletely burned organic pollutants in the tail gas.

[0051] In the present invention, the waste activated carbon includes waste activated carbon that adsorbs organic pollutants and / or waste activated carbon that adsorbs inorganic salt pollutants.

[0052] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0053] Example 1

[0054] The raw material is saturated adsorption activated carbon used for post-extraction wastewater treatment, with a particle size of 5 to 150 mesh. After testing, the types of pollutants that need to be removed are mainly organic extractants of sulfonated kerosene, and other trace metal salts such as nickel, calcium, magnesium, and chromium.

[0055] (1) The waste activated carbon is washed with a dilute acid solution, screened, sorted, impurity removed, and filtered to remove some high-salt impurities mixed with the activated carbon and some adsorbents coated on the surface.

[0056] (2) The saturated adsorption waste activated carbon after cleaning and impurity removal is quantitatively added to the drying furnace by a belt conveyor unit for drying. The drying method is microwave drying, the drying feed rate is 30 kg / h, the drying temperature is 120°C, and the atmosphere is nitrogen. The water vapor and flue gas generated during the drying process are separated by solid and gas and then enter the exhaust gas treatment system. The waste activated carbon dust obtained after solid and gas separation is mixed with the dried waste activated carbon for microwave regeneration. The moisture content of the dried waste activated carbon is 8% (±2%).

[0057] (3) The microwave pyrolysis regeneration furnace is preheated to 650°C, and then the dried waste activated carbon with a particle size of 5 to 80 mesh is transported to the microwave regeneration furnace for desorption of adsorbed substances, and the furnace temperature is controlled at 650°C; nitrogen is continuously introduced during the regeneration process to prevent the activated carbon from coming into contact with oxygen and oxidizing during the regeneration process. The microwave pyrolysis regeneration furnace is slightly positively pressurized, and the relative pressure is controlled at 20kPa to prevent the entry of external air and the leakage of harmful gases. The furnace body rotation device is a variable frequency speed regulation motor with gear transmission, and the feed rate is controlled at 40kg / h. The small amount of water and most of the organic matter extracted from the pyrolysis regeneration furnace are collected by cyclone dust removal, and the regenerated activated carbon dust contained in the exhaust gas is then sent into the exhaust gas treatment system. The regenerated activated carbon dust is the regenerated activated carbon product. After keeping warm for 0.5h, the regenerated activated carbon is sent to a water-cooled screw conveyor with nitrogen protective gas for cooling (in order to avoid direct contact of activated carbon with oxygen under high temperature conditions, a water-cooled screw conveyor is used to cool the discharge temperature of the regenerated activated carbon to below 100°C to prevent oxidation of the regenerated activated carbon). After cooling, the regenerated activated carbon material and the separated regenerated activated carbon dust are sent to the collecting bin together to complete the regeneration.

[0058] The tail gas treatment system in step (2) and step (3) is the same system, specifically including a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower. In this embodiment, the exhaust gas in the drying stage of the waste activated carbon mainly contains ethane, propylene, propane, 1-butene, 1-hexene, n-heptane, n-undecane, naphthalene, etc.; the exhaust gas in the pyrolysis stage mainly contains ethylene, acetylene, ethylene, propylene, benzene, toluene, styrene, naphthalene, etc., which are all organic gases that evaporate during drying or are incompletely produced during pyrolysis. On this basis, there are trace acidic gases produced by pyrolysis of salts; therefore, the exhaust gas generated during the regeneration process is treated in the following manner: a sodium hydroxide solution with a pH value of 10 is sprayed in the first spray tower to remove the acidic gas, the combustion temperature of the secondary combustion chamber is 1200°C, and SNCR desulfurization and denitrification treatment is performed, and a NaOH solution with a pH value of 10 is sprayed in the second spray tower to prevent some smoke or nitrogen-containing gas that may still remain in the exhaust gas after the secondary combustion chamber treatment from being discharged into the atmosphere.

[0059] The iodine adsorption value recovery rate of the activated carbon material after regeneration in this embodiment is 97.75%, which is basically the same as the particle size ratio of the unregenerated activated carbon, and the mechanical properties are 99.2%.

[0060] Figure 1 These are photos of the spent activated carbon before and after regeneration in this embodiment. Figure 1 (A) is a photo of waste activated carbon raw materials. Figure 1 (B) is a photo of the waste activated carbon after washing, screening, impurity removal, filter pressing and drying. Figure 1 (C) is a photo of waste activated carbon after microwave regeneration. Figure 1 It can be seen that there are obvious white salt powder particles on the surface of the initial material, and there are also salt-containing activated carbon agglomerates, which are fragile and feel powdery; the salt crystals on the surface of the dried material disappear, and the salt-containing activated carbon agglomerates appear burnt, fragile, and brittle; there are no agglomerates or salt crystals on the surface of the recycled material, and the material is fluffy and dry.

[0061] The activated carbon material regenerated in Example 1 was re-added to the wastewater after extraction for adsorption treatment, and the saturated adsorption waste activated carbon obtained was regenerated again in the manner of Example 1 to verify the recycling regeneration ability of this process. The adsorption capacity performance of the regenerated activated carbon obtained after the second cycle regeneration was restored to 94.91% of the new activated carbon, and reached 88.29% at the third time. When the fifth cycle regeneration was reached, the adsorption capacity performance of the regenerated activated carbon obtained was about 80% of the new activated carbon. At this time, the performance of the activated carbon barely met the needs of the enterprise. Therefore, it can be inferred that the number of cycle regenerations should be 5 times. During multiple cycles, the mechanical strength performance of the activated carbon regeneration product did not change significantly. When the number of cycle regenerations reached 5 times, the mechanical strength of the regenerated activated carbon was about 95% of the new activated carbon. This shows that the activated carbon product regenerated using this process has excellent recycling performance.

[0062] Example 2

[0063] The only difference from Example 1 is that the temperature of microwave regeneration is 700°C.

[0064] Example 3

[0065] The only difference from Example 1 is that the microwave regeneration temperature is 750°C.

[0066] Example 4

[0067] The only difference from Example 1 is that the temperature of microwave regeneration is 800°C.

[0068] The adsorption capacity of the waste activated carbon before and after adsorption in Examples 1 to 4 is shown in Table 1.

[0069] Table 1 Adsorption capacity of waste activated carbon before and after adsorption in Examples 1 to 4

[0070]

[0071] From the data in Table 1, it can be seen that the microwave regeneration process has a significant regeneration effect and a good continuous operation effect. The carbon loss rate of the material under this process is low, which can greatly reduce the loss of activated carbon.

[0072] Example 5

[0073] The raw material is saturated adsorption activated carbon used for post-extraction wastewater treatment, with a particle size of 5 to 150 mesh. After testing, the types of pollutants that need to be removed are mainly organic extractants of sulfonated kerosene, and other trace metal salts such as nickel, calcium, magnesium, and chromium.

[0074] (1) The waste activated carbon is cleaned, screened, impurity-removed, and filtered to remove impurities contained in the waste activated carbon and part of the adsorbents coated on the surface.

[0075] (2) The saturated adsorption waste activated carbon after cleaning and impurity removal is quantitatively added to the drying furnace by a belt conveyor unit for drying. The drying method is hot air drying, the drying feed rate is 35 kg / h, the drying temperature is 140 ° C, the atmosphere is nitrogen atmosphere, and the powder leakage is strictly controlled during the transportation process. The water vapor and flue gas generated during the drying process are separated by solid and gas and then enter the exhaust gas treatment system. The waste activated carbon dust obtained after solid and gas separation is mixed with the dried waste activated carbon for microwave regeneration. The moisture content of the dried waste activated carbon is 8% (± 2%).

[0076] (3) The microwave pyrolysis regeneration furnace is preheated to 750°C, and then the dried waste activated carbon with a particle size of 5 to 80 mesh and the waste activated carbon powder with a particle size below 80 mesh are mixed in a mass ratio of 8:1, and then transported to the microwave regeneration furnace for desorption of adsorbed substances. The furnace temperature is controlled at 750°C; nitrogen is continuously introduced during the regeneration process to prevent the activated carbon from contacting with oxygen and causing oxidation during the regeneration process. The microwave pyrolysis regeneration furnace is slightly positively pressurized, and the relative pressure is controlled at 13kPa to prevent the entry of external air and the leakage of harmful gases. The furnace body rotation device is a variable frequency speed regulation motor with gear transmission. The small amount of water and most of the organic matter extracted from the pyrolysis regeneration furnace are collected by cyclone dust removal, and the regenerated activated carbon dust contained in the exhaust gas is then sent to the exhaust gas treatment system. The regenerated activated carbon dust is the regenerated activated carbon product. After keeping warm for 0.5h, the regenerated activated carbon is sent to a water-cooled screw conveyor with nitrogen protective gas for cooling (in order to avoid direct contact of activated carbon with oxygen under high temperature conditions, a water-cooled screw conveyor is used to cool the discharge temperature of the regenerated activated carbon to below 100°C to prevent oxidation of the regenerated activated carbon). After cooling, the regenerated activated carbon material and the separated regenerated activated carbon dust are sent to the collecting bin together to complete the regeneration.

[0077] The tail gas treatment system in step (2) and step (3) is the same system, specifically including a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower arranged in sequence. In this embodiment, sodium hydroxide solution with a pH value of 10 is sprayed in both the first spray tower and the second spray tower, and the combustion temperature of the secondary combustion chamber is 1200°C, and SNCR desulfurization and denitrification treatment is performed.

[0078] The iodine adsorption value recovery rate of the activated carbon material after regeneration in this embodiment is 97.40%, which is basically the same as the particle size ratio of the unregenerated activated carbon, and the mechanical properties are 98.8%.

[0079] Example 6

[0080] The raw material is saturated adsorption activated carbon used for post-extraction wastewater treatment, with a particle size of 5 to 150 mesh. After testing, the types of pollutants that need to be removed are mainly organic extractants of sulfonated kerosene, and other trace metal salts such as nickel, calcium, magnesium, and chromium.

[0081] (1) The waste activated carbon is cleaned, screened, impurity-removed, and filtered to remove impurities contained in the waste activated carbon and part of the adsorbents coated on the surface.

[0082] (2) The saturated adsorption waste activated carbon after cleaning and impurity removal is quantitatively added to the drying furnace by a belt conveyor unit for drying. The drying method is hot air drying, the drying feed rate is 30 kg / h, the drying temperature is 120 ° C, the atmosphere is a nitrogen atmosphere, and the powder leakage is strictly controlled during the transportation process. The water vapor and flue gas generated during the drying process are separated by solid and gas and then enter the exhaust gas treatment system. The waste activated carbon dust obtained after solid and gas separation is mixed with the dried waste activated carbon for microwave regeneration. The moisture content of the dried waste activated carbon is 8% (± 2%).

[0083] (3) The microwave pyrolysis regeneration furnace is preheated to 700°C, and then the dried waste activated carbon with a particle size of 5 to 80 mesh and the waste activated carbon powder with a particle size below 80 mesh are mixed in a mass ratio of 10:1, and then transported to the microwave regeneration furnace for desorption of adsorbed substances. The furnace temperature is controlled at 700°C; nitrogen is continuously introduced during the regeneration process to prevent the activated carbon from contacting with oxygen and causing oxidation during the regeneration process. The microwave pyrolysis regeneration furnace is slightly positively pressurized, and the relative pressure is controlled at 15kPa to prevent the entry of external air and the leakage of harmful gases. The furnace body rotation device is a variable frequency speed regulation motor with gear transmission. The small amount of water and most of the organic matter extracted from the pyrolysis regeneration furnace are collected by cyclone dust removal, and the regenerated activated carbon dust contained in the exhaust gas is then sent to the exhaust gas treatment system. The regenerated activated carbon dust is the regenerated activated carbon product. After keeping warm for 1 hour, the regenerated activated carbon is sent to a water-cooled screw conveyor with nitrogen protective gas for cooling (in order to avoid direct contact of activated carbon with oxygen under high temperature conditions, a water-cooled screw conveyor is used to cool the discharge temperature of the regenerated activated carbon to below 100°C to prevent oxidation of the regenerated activated carbon). After cooling, the regenerated activated carbon material and the separated regenerated activated carbon dust are sent to the collection bin together to complete the regeneration.

[0084] The tail gas treatment system in step (2) and step (3) is the same system, specifically including a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower arranged in sequence. In this embodiment, sodium hydroxide solution with a pH value of 10 is sprayed in both the first spray tower and the second spray tower, and the combustion temperature of the secondary combustion chamber is 1200°C, and SNCR desulfurization and denitrification treatment is performed.

[0085] The iodine adsorption value recovery rate of the activated carbon material after regeneration in this embodiment is 96.35%, which is basically the same as the particle size ratio of the unregenerated activated carbon, and the mechanical properties are 99.3%.

[0086] Example 7

[0087] The raw material is saturated adsorption activated carbon used for post-extraction wastewater treatment, with a particle size of 5 to 150 mesh. After testing, the types of pollutants that need to be removed are mainly organic extractants of sulfonated kerosene, and other trace metal salts such as nickel, calcium, magnesium, and chromium.

[0088] (1) The waste activated carbon is cleaned, screened, impurity-removed, and filtered to remove impurities contained in the waste activated carbon and part of the adsorbents coated on the surface.

[0089] (2) The saturated adsorption waste activated carbon after cleaning and impurity removal is quantitatively added to the drying furnace by a belt conveyor unit for drying. The drying method is hot air drying, the drying feed rate is 20 kg / h, the drying temperature is 80 ° C, and the atmosphere is nitrogen atmosphere. The leakage of powder is strictly controlled during the transportation process. The water vapor and flue gas generated during the drying process are separated by solid and gas and then enter the exhaust gas treatment system. The waste activated carbon dust obtained after solid and gas separation is mixed with the dried waste activated carbon for microwave regeneration. The moisture content of the dried waste activated carbon is 8% (± 2%).

[0090] (3) The microwave pyrolysis regeneration furnace is preheated to 800°C, and then the dried waste activated carbon with a particle size of 5 to 80 mesh is transported to the microwave regeneration furnace for desorption of adsorbed substances. The furnace temperature is controlled at 800°C. Nitrogen is continuously introduced during the regeneration process to prevent the activated carbon from coming into contact with oxygen and oxidizing during the regeneration process. The microwave pyrolysis regeneration furnace is slightly positively pressurized, and the relative pressure is controlled at 20kPa to prevent the entry of outside air and the leakage of harmful gases. The furnace body rotation device is a variable frequency speed regulation motor with gear transmission. The small amount of water and most of the organic matter extracted from the pyrolysis regeneration furnace are collected by cyclone dust removal. The regenerated activated carbon dust contained in the exhaust gas is then sent to the exhaust gas treatment system. The regenerated activated carbon dust is the regenerated activated carbon product. After keeping warm for 1 hour, the regenerated activated carbon is sent to a water-cooled screw conveyor with nitrogen protective gas for cooling (in order to avoid direct contact of activated carbon with oxygen under high temperature conditions, a water-cooled screw conveyor is used to cool the discharge temperature of the regenerated activated carbon to below 100°C to prevent oxidation of the regenerated activated carbon). After cooling, the regenerated activated carbon material and the separated regenerated activated carbon dust are sent to the collection bin together to complete the regeneration.

[0091] The tail gas treatment system in step (2) and step (3) is the same system, specifically including a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower arranged in sequence. In this embodiment, sodium hydroxide solution with a pH value of 10 is sprayed in both the first spray tower and the second spray tower, and the combustion temperature of the secondary combustion chamber is 1200°C, and SNCR desulfurization and denitrification treatment is performed.

[0092] The iodine adsorption value recovery rate of the activated carbon material after regeneration in this embodiment is 95.55%, which is basically the same as the particle size ratio of the unregenerated activated carbon, and the mechanical properties are 99.2%.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A continuous regeneration process for saturated adsorption waste activated carbon, characterized in that: The following steps are involved: 1) washing, screening, removing impurities and filtering the waste activated carbon in sequence to obtain pretreated waste activated carbon; 2) drying the pretreated waste activated carbon to obtain dried waste activated carbon and dried tail gas; 3) regenerating the dried waste activated carbon by microwave to obtain activated regenerated activated carbon and activated regenerated tail gas; The dried tail gas is subjected to gas-solid separation to obtain separated tail gas and recovered activated carbon dust, and the recovered activated carbon dust is mixed with the waste activated carbon dried in step 3) and subjected to microwave regeneration; The separated tail gas enters the tail gas treatment system; The activated regenerated tail gas is subjected to dust removal to obtain activated carbon dust after activation and regeneration and dust-removed tail gas; the activated carbon dust after activation and regeneration is used as activated carbon after activation and regeneration; the dust-removed tail gas enters the tail gas treatment system; The tail gas treatment system includes a first spray tower, a secondary combustion chamber, a quenching tower, a bag dust collector and a second spray tower which are arranged in sequence.

2. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 1, characterized in that: The drying temperature in step 2) is 80-150° C.; The moisture content of the dried waste activated carbon is 5-10%.

3. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 2, characterized in that: When the particle size of the dried waste activated carbon in step 3) is 5 to 80 mesh, it can be directly subjected to microwave regeneration; When the particle size of the dried waste activated carbon is less than 80 meshes, it needs to be mixed with waste activated carbon with a particle size of 5 to 80 meshes and then subjected to microwave regeneration, and the mass ratio of the two is 1:2 to 10.

4. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 3, characterized in that: The microwave regeneration temperature in step 3) is 500-850° C., and the time is 0.5-2 h.

5. A continuous regeneration process for saturated adsorption waste activated carbon according to any one of claims 1 to 4, characterized in that: The atmosphere of the microwave regeneration is an oxygen-free atmosphere.

6. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 5, characterized in that: The pressure of the microwave regeneration is 5-20 kPa.

7. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 6, characterized in that: The first spray tower is for alkali spraying; The alkali solution is a sodium hydroxide solution with a pH value of 9-12.

8. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 7, characterized in that: The combustion temperature of the secondary combustion chamber is 1000-1500°C.

9. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 8, characterized in that: The second spray tower is a cooling and dust removal tower.

10. The continuous regeneration process of saturated adsorption waste activated carbon according to claim 9, characterized in that: The waste activated carbon includes waste activated carbon that adsorbs organic pollutants and / or waste activated carbon that adsorbs inorganic salt pollutants.

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