Method and system for regenerating activated carbon

Abstract

Adsorption performance is recovered and improved by regenerating used powdery activated carbon using microwave heating. This method for regenerating activated carbon involves: a step for placing activated carbon having an average particle diameter of 1-100 μm on a flat plate; and a step for subjecting the activated carbon on the flat plate to microwave heating to regenerate the activated carbon. While microwave heating is being performed, the flat plate may be repeatedly moved forward and backward by a belt conveyor or a roller conveyor. The temperature of the activated carbon during microwave heating may be measured, and microwave irradiation energy may be controlled on the basis of a measurement result.

Description

Activated carbon regeneration method and regeneration system

[0001] The present invention relates to a regeneration method and a regeneration system for recovering the adsorption performance of used activated carbon by desorbing and separating substances adsorbed on the activated carbon from the activated carbon using microwave heating.

[0002] Common types of regeneration furnaces used to regenerate activated carbon include multi-furnace regeneration furnaces for large furnaces, with four to eight stacked cylindrical furnace chambers, rotary kiln regeneration furnaces for medium-sized furnaces, and direct current superheating regeneration furnaces for small furnaces, which are heated by passing current through electrodes. Currently, all regeneration furnaces in Japan use external heating methods that use fossil fuels such as heavy oil and gas as their heat source. When regenerating activated carbon using external heating, heat is transferred to the interior by thermal conduction, resulting in low thermal conductivity. For this reason, external heating is inefficient for heating large objects, and requires long heating times.

[0003] Conventional heating furnace activated carbon regeneration systems are limited in the particle size they can regenerate. Specifically, when regenerating powders finer than 40 mesh (0.56 mm), particularly powdered activated carbon with a particle size distribution of 1 to 100 μm, dust dispersion problems occur, preventing their practical application. Therefore, granular activated carbon with larger particle sizes can be reused by recovering it after adsorption and regenerating it by heating it in a regeneration furnace. However, powdered activated carbon with smaller particle sizes is recovered as solid-liquid separated material or dehydrated cake after new use and disposed of as industrial waste. Alternatively, used powdered activated carbon has been recycled for use in livestock feed or soil fertilizer, resulting in lower added-value applications.

[0004] In recent years, with the growing need for carbon neutrality efforts by 2050 and the spread of the concept of a carbon circular economy, research is being conducted into microwave heating recycling, which allows for a switch to non-fossil energy. In recycling methods using microwave heating, a microwave electric field penetrates the object to be heated and is converted into thermal energy from the inside, so internal heating can be achieved in a short time without the need for thermal conduction.

[0005] However, microwave heating has had the problem of insufficient measures to prevent uneven heating during the process of scaling up to an actual plant, resulting in low recovery performance values ​​for regenerated activated carbon.

[0006] As a method for regenerating activated carbon using microwave heating, Patent Document 1 describes a method in which used activated carbon is stored in a cylindrical heating container, and an empty space is provided that is greater than or equal to the volume of the used activated carbon, thereby enabling uniform microwave irradiation of the activated carbon.

[0007] Patent Document 2 describes a regeneration method in which hot water is blown into the activated carbon to remove the carbonized organic matter desorbed from the used activated carbon by microwave heating regeneration, and the volume expands as the water turns into steam, providing a blow-out removal effect.

[0008] Patent Document 3 describes a method in which activated carbon is placed in a circulation path, the activated carbon is heated by microwaves to desorb the adsorbates from the activated carbon, and the activated carbon is regenerated; a mixed gas of an inert gas circulating in the circulation path and the desorbed adsorbate gas is cooled and condensed, and the adsorbates are separated and recovered.

[0009] Japanese Patent Application Laid-Open No. 2001-89120 Japanese Patent Application Laid-Open No. 2001-89121 Japanese Patent Application Laid-Open No. 6-31163

[0010] An object of the present invention is to provide a regeneration method and a regeneration system that can regenerate used powdered activated carbon by microwave heating and restore and improve its adsorption performance.

[0011] [1] A method for regenerating activated carbon, comprising the steps of: placing activated carbon having an average particle size of 1 to 100 μm on a flat plate; and regenerating the activated carbon on the flat plate by microwave heating.

[0012] [2] The method for regenerating activated carbon according to [1], wherein the flat plate is repeatedly moved forward and backward by a belt conveyor or a roller conveyor during microwave heating.

[0013] [3] The method for regenerating activated carbon according to [1], wherein the temperature of the activated carbon is measured during microwave heating, and microwave irradiation energy is controlled based on the measurement result.

[0014] [4] The method for regenerating activated carbon according to [1], wherein the activated carbon is heated by microwaves in a heat treatment box having an oxygen concentration of 2% or less.

[0015] [5] The method for regenerating activated carbon according to [4], wherein the exhaust gas from the heat treatment box is treated and the treated gas is supplied to the heat treatment box.

[0016] [6] The method for regenerating activated carbon according to [1], wherein the height of the activated carbon on the plate is made uniform using a leveling plate before microwave heating.

[0017] [7] An activated carbon regeneration system comprising: a hopper that supplies activated carbon having an average particle size of 1 to 100 μm onto a flat plate; a leveling plate that adjusts the height of the activated carbon on the flat plate to a constant level; a transport unit that transports the flat plate on which the activated carbon is placed to a heat treatment box; and a microwave generator that irradiates microwaves into the heat treatment box.

[0018] [8] The activated carbon regeneration system described in [7], wherein the transport unit has a belt conveyor or a roller conveyor, and repeatedly moves the flat plate on which the activated carbon is placed forward and backward within the heat treatment box during microwave irradiation.

[0019] According to the present invention, used powdered activated carbon can be regenerated by microwave heating, and its adsorption performance can be restored and improved.

[0020] Fig. 1 is a schematic diagram of an activated carbon regeneration system according to an embodiment of the present invention. Fig. 2 is a functional block diagram of a control device. Fig. 3 is a graph showing an example of a change in microwave irradiation energy during activated carbon regeneration treatment. Fig. 4 is a graph showing an example of a change in temperature during activated carbon regeneration treatment.

[0021] Hereinafter, an embodiment will be described with reference to the drawings.

[0022] The activated carbon regeneration system according to the embodiment of the present invention shown in FIG. 1 regenerates used activated carbon by heating it with microwaves, and is particularly suitable for regenerating powdered activated carbon with small particle sizes.

[0023] Used activated carbon 1 to be regenerated is supplied from a hopper 2 onto a plate 3. The activated carbon 1 is powdered activated carbon with an average particle size of 1 to 100 μm. The average particle size of the powdered activated carbon is determined by the median diameter D measured by a laser diffraction particle size distribution analyzer. ５０ The used activated carbon 1 to be regenerated is not particularly limited, but may be, for example, activated carbon having an iodine adsorption capacity of 50 to 1800 mg / g and a specific surface area of ​​300 to 2000 m. ２ / g of used activated carbon.

[0024] The plate 3 is made of quartz or a metal such as SUS. The plate 3 is, for example, a flat plate having a rectangular shape in a plan view. The dimensions of the plate 3 are not particularly limited. A substantially rectangular frame is provided on one main surface (front surface) of the plate 3, and activated carbon 1 supplied from the hopper 2 is spread inside the frame.

[0025] The plate 3 on which the activated carbon 1 is placed is transported to a heat treatment box 6 by a transport unit 4. The transport unit 4 is, for example, a belt conveyor or a roller conveyor.

[0026] A leveling plate 5 is provided near the hopper 2, and as the plate 5 moves, the height of the activated carbon 1 spread within the frame becomes constant.

[0027] When the plate 3 is transported into the heat treatment box 6, the microwave leakage prevention shutter 11 closes, creating an airtight space inside the box 6. A microwave generator 7 is connected to the heat treatment box 6. Microwaves generated by the microwave generator 7 are guided into the heat treatment box 6 and heat the activated carbon 1 (and the plate 3). The microwaves are irradiated from multiple points on the top of the heat treatment box 6. A microwave source with a frequency of 2.45 GHz and a maximum output of approximately 24 kW is used. An example of a microwave source is a microwave oven.

[0028] The control device 20 controls the microwave irradiation energy. The control method will be described later.

[0029] The heat treatment box 6 may be provided with a sensor (not shown) that measures the reflected energy of microwaves. Also, a meter that uses the principle of a differential calorimeter and can measure the carbonization and carbon dioxide conversion of the adsorbed substance may be installed.

[0030] A propeller 9 that evenly reflects microwaves may be installed inside the heat treatment box 6. The propeller 9 is made of metal such as SUS. The number of blades on the propeller 9 is not limited and may be, for example, about 2 to 5. Multiple propellers 9 may be installed.

[0031] During microwave irradiation, the plate 3 may be moved back and forth (repeatedly moving forward and backward) inside the heating treatment box 6 by the conveying unit 4 at a low speed that does not cause the powdered activated carbon to scatter, thereby suppressing uneven heating.

[0032] The exhaust gas generated by heating the activated carbon 1 is discharged by a blower (not shown) from an exhaust pipe 8 connected to the heat treatment box 6. The exhaust gas discharged from the exhaust pipe 8 is measured for TOC (total organic carbon) and wet concentration by a gas analyzer (not shown). The exhaust pipe 8 is provided with a gas flow meter (not shown) that measures the ventilation flow rate of the blower.

[0033] A supply pipe (not shown) for supplying nitrogen gas, superheated steam, or carbon dioxide gas is connected to the heat treatment box 6. The exhaust gas discharged from the exhaust pipe 8 is treated using a known exhaust gas treatment method such as scrubber treatment or plasma treatment. Since the treated gas has a low oxygen concentration, it is preferable to return it to the heat treatment box 6. Maintaining a low oxygen concentration in the heat treatment box 6 (for example, 0.2% or less) can prevent carbon components from being discharged outside the system as carbon dioxide, thereby improving the recovery rate of recycled products.

[0034] An infrared camera 10 is installed in the heat treatment box 6 to measure the temperature of the activated carbon 1 on the plate 3. A heat conduction type thermometer to measure the temperature of the activated carbon 1 may also be provided.

[0035] When the regeneration process of the activated carbon 1 is completed, the microwave leakage prevention shutter 11 opens, and the plate 3 is carried out from the heat treatment box 6. The regenerated activated carbon 1 is recovered from the plate 3.

[0036] The control device 20 is a computer having a CPU and a memory, and has the functions of a temperature acquisition unit 21, an exhaust gas component acquisition unit 22, a flow rate acquisition unit 23, a reflected energy amount acquisition unit 24, and a microwave irradiation energy control unit 25, as shown in FIG.

[0037] The temperature acquisition unit 21 acquires the temperature of the activated carbon 1 during the regeneration treatment from the infrared camera 10 or the like.

[0038] The exhaust gas component acquisition unit 22 acquires the analysis results of the TOC and wet concentration of the exhaust gas from the gas analyzer.

[0039] The flow rate acquisition unit 23 acquires the measurement result of the ventilation flow rate of the blower from the gas flow meter.

[0040] The reflected energy amount acquisition unit 24 acquires the measurement result of the reflected energy amount of the microwave. The consumed energy amount of the microwave is calculated from the difference between the irradiated energy amount and the reflected energy amount.

[0041] The activated carbon regeneration method according to this embodiment includes a drying step for removing moisture from used activated carbon, a calcination / desorption step for calcining and desorbing the substances adsorbed by the activated carbon (adsorbate), a reactivation step for gasifying the remaining carbonized adsorbate, and a cooling step for cooling the activated carbon.

[0042] The microwave irradiation energy control unit 25 judges the state of the activated carbon 1 based on the temperature of the activated carbon 1, the exhaust gas components, etc., determines which process to execute from the drying process, the calcination desorption process, the reactivation process, and the cooling process, and outputs a control signal to the microwave generator 7 so that the irradiation energy is appropriate for the process.

[0043] Figure 3 shows an example of the change in microwave irradiation energy during the regeneration treatment, and Figure 4 shows an example of the change in temperature of the powdered activated carbon 1 during the regeneration treatment.

[0044] After purging the heating treatment box 6 with nitrogen, microwave irradiation is started to carry out the drying process (period T1 in FIGS. 3 and 4). In the drying process, the temperature of the activated carbon rises due to microwave irradiation, and the initial moisture evaporates, resulting in a constant temperature of around 100°C.

[0045] When the moisture contained in the activated carbon evaporates and the drying process is completed, the temperature rises rapidly to above 100°C. The microwave irradiation energy is reduced to maintain the regeneration temperature at a predetermined temperature, and the calcination desorption process is carried out (period T2 in Figures 3 and 4). The predetermined regeneration temperature in the calcination desorption process is set to an optimum temperature depending on the amount of adsorbed substance and the carbonization rate. For example, the calcination desorption process is carried out at a temperature range of 200 to 1400°C, preferably 500 to 1200°C.

[0046] In the initial stage of the calcination / desorption step, microwave energy is used for the desorption reaction of the adsorbate. In the latter half of the calcination / desorption step (period T2), when desorption of the adsorbate has progressed to a certain extent, the irradiation energy is adjusted to a slightly lower level to maintain a constant temperature of the activated carbon. For example, the irradiation energy in the latter half of the calcination / desorption step is adjusted to approximately 80 to 95% of the irradiation energy in the first half.

[0047] When it is determined from the analysis results of the exhaust gas that the components of the adsorbed substances in the exhaust gas have fallen below a predetermined value, marking the end of the calcination / desorption process, the irradiation energy is increased to raise the regeneration temperature, and a reactivation process is carried out (period T3 in Figures 3 and 4). The end of the calcination / desorption process may also be determined by monitoring the carbonization removal status based on differential calorimetry measurements and the amount of microwave energy consumed. In the reactivation process, the adsorbed substances remaining in the calcination / desorption process and carbonized are gasified by contacting them with superheated steam, carbon dioxide, or an oxidizing gas such as oxygen (water-gas reaction), and then discharged from the exhaust pipe 8. For example, the irradiation energy in the reactivation process is set to be slightly higher than that in the calcination / desorption process and lower than that in the drying process.

[0048] It is known that the upper limit of the temperature and residence time for reactivation can be determined based on the gasification loss of the activated carbon itself. The higher the temperature, the shorter the residence time can be exponentially.

[0049] When it is determined from the analysis results of the exhaust gas that the components of the adsorbed substances in the exhaust gas have fallen below a predetermined value, indicating that the reactivation process has ended, the microwave irradiation is stopped and a cooling process is carried out (period T4 in Figures 3 and 4) to cool the activated carbon to below 100°C. To avoid a sudden drop in temperature, the temperature is gradually lowered by ventilation using a blower in a nitrogen purged atmosphere or a low-oxygen atmosphere of 2% or less. Ventilation may be performed by circulating the exhaust gas after scrubber treatment.

[0050] This regeneration process can restore the adsorption performance of used powdered activated carbon to the same level as new powdered activated carbon. By subjecting new powdered activated carbon to the same process, the adsorption performance can be further improved.

[0051] In this embodiment, the powdered activated carbon to be regenerated is placed on a plate 3 and leveled to a certain thickness before being irradiated with microwaves, thereby preventing ignition and uneven heating due to scattering of fine powder. In this embodiment, the temperature of the activated carbon on the plate 3 and the components of the exhaust gas are monitored by instruments during the regeneration process to control the microwave irradiation energy, thereby improving the quality of the regenerated product. By making it possible to regenerate powdered carbon, it can be reused as regenerated powdered carbon, which has high added value in food processing, thereby reducing costs compared to using new carbon.

[0052] In the conventional activated carbon regeneration process using heat transfer from external heat, in addition to heating the used activated carbon, heat loss occurs due to heating of the heating furnace device itself and heat transfer to the surroundings. However, in the microwave irradiation of this embodiment, the activated carbon 1 is directly heated and heat transfer is mainly to the plate 3 that contacts the activated carbon 1, so thermal regeneration can be performed efficiently. Therefore, the CO2 converted from fossil energy such as gas and heavy oil in the conventional external heating method is ２ CO emissions converted from the electricity consumed by microwave heating ２ The amount of waste generated is expected to be significantly reduced.

[0053] Heat regeneration by microwave irradiation enables conversion to non-fossil energy, and depending on the type of electricity used, carbon neutrality is possible. Heat regeneration by microwave irradiation reduces CO2 emissions by recycling used activated carbon. ２ This is expected to reduce the amount of waste generated and, secondarily, reduce the carbon footprint of customers' manufactured products.

[0054] Conventionally, the regeneration control temperature has been uniformly managed within a temperature range of 800 to 850°C for versatility, but in this embodiment, the optimal regeneration temperature can be set based on differential calorimetry and desorption endpoint prediction, making regeneration possible even at 500 to 600°C. This makes it possible to conserve thermal energy.

[0055] In the above embodiment, the used powdered activated carbon to be regenerated may be powdered activated carbon alone, or may be mixed with a filter material, such as diatomaceous earth powder, used in precoat filtration for decolorization processes or other target adsorption processes. It is desirable to sufficiently reduce the moisture content of the powdered activated carbon and powdered diatomaceous earth mixture. The moisture content is preferably 80% or less, and more preferably 50% or less.

[0056] The activated carbon regeneration system according to the above embodiment can regenerate powdered activated carbon with an average particle size of 1 to 100 μm. However, the activated carbon regeneration system according to the above embodiment can also be applied to the regeneration of crushed or pelleted granular activated carbon with a particle size of 100 μm or more (100 μm to 10 mm). The activated carbon regeneration system according to the above embodiment makes it possible to switch to non-fossil energy for the regeneration of various types of used activated carbon, regardless of particle size, and reduces CO2 emissions significantly. ２ It is possible to reduce the amount of waste generated.

[0057] The activated carbon regeneration system according to the above embodiment has been described as being configured to suppress uneven heating by moving the plate 3 carrying the powdered activated carbon 1 back and forth within the heating treatment box 6 using a belt conveyor or the like, but the plate 3 may also be rotated on a turntable.

[0058] The adsorbent to be regenerated is not limited to carbon-based adsorbents including activated carbon and activated carbon fiber materials, but may also be zeolite, silica gel, alumina, etc.

[0059] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0060] Example 1: A used adsorbent sample was prepared by mixing powdered activated carbon (average particle size 37 μm) after adsorption of organic matter and diatomaceous earth powder (average particle size 24 μm) after filtration in a weight ratio of 9:1 (water content 40%). The iodine adsorption capacity of this sample before regeneration was 170 mg / g. A square frame (external dimensions 100 mm x 100 mm x height 20 mm, thickness 10 mm) was placed on a quartz plate (130 mm x 130 mm x 10 mm). 50.31 g of sample was spread evenly within the frame and placed on a turntable in a microwave irradiation box (400 mm x 400 mm x 400 mm).

[0061] The microwave irradiation box was purged with nitrogen at a flow rate of 10 L / min for 5 minutes, and then microwave heating regeneration was initiated. Microwave irradiation was performed while rotating the turntable at 7 rpm. The blower flow rate for discharging the desorbed gas out of the system was 4.5 m. ３ The microwave irradiation energy was changed in the following order: 1000 W for 180 seconds, 500 W for 660 seconds, 700 W for 180 seconds, 900 W for 300 seconds, and 1000 W for 180 seconds.

[0062] At the blower outlet, which discharges gas from the microwave irradiation box to the outside of the system, the smell of water vapor and desorbed components was detected when the temperature reached 100°C. When the temperature reached 600°C, white smoke was emitted from the desorbed gas along with a burnt odor. The temperature was then maintained until the white smoke subsided, and then the burnt odor gradually disappeared. The test was terminated when the odor had sufficiently subsided. When the white smoke first began to be emitted, it is believed that not only was the adsorbate vaporizing, but also the carbonization of the desorbed components had begun. After that, when the odor disappeared, it is believed that almost all of the adsorbates had been desorbed from the used activated carbon and diatomaceous earth.

[0063] The sample after heat regeneration was recovered, and its weight and iodine adsorption capacity were measured. The measurement results are shown in Table 1. It was confirmed that the iodine adsorption capacity was restored to 580 mg / g.

[0064] Example 2: 70.01 g of sample was spread inside the frame, and the thermal regeneration of Example 2 was carried out in the same manner as in Example 1, except that the microwave irradiation energy was changed in the following order: 1000 W for 780 seconds, 1200 W for 120 seconds, and 1400 W for 900 seconds. The measurement results are shown in Table 1. It was confirmed that the iodine adsorption performance was restored to 580 mg / g.

[0065] Example 3: A square frame (external dimensions: 200 mm x 200 mm x 20 mm, width: 10 mm) was placed on a 380 mm x 380 mm x 2 mm SUS plate. 1205 g of sample was placed inside the frame. The four corners of the frame were positioned so that the sample formed an arc with a curvature radius of 30 mm to avoid local heating. The SUS plate on which the sample was placed was fixed to the center of the bottom of a belt conveyor-type microwave irradiation box (length: 700 mm, width: 1500 mm, height: 1200 mm). To ensure uniform microwave irradiation, propellers (70 mm x 150 mm x 4) installed at a 45-degree angle at two locations on the top were rotated at 7 rpm. The blower flow rate for discharging the desorbed gas was 7.5 m / s. ３ The microwave irradiation energy was varied as follows: 2000 W for 1800 seconds, 1000 W for 420 seconds, 2000 W for 300 seconds, and 2500 W for 780 seconds. The test was terminated when the odor of the exhaust gas had sufficiently disappeared.

[0066] The sample after heat regeneration was recovered, and its weight and iodine adsorption capacity were measured. The measurement results are shown in Table 1. It was confirmed that the iodine adsorption capacity was restored to 530 mg / g.

[0067] Example 4: 1200 g of sample was spread inside a frame, and the sample was moved inward to form a 30 mm square circle to avoid localized heating at the corners. The microwave irradiation energy was varied to 2000 W for 1740 seconds, 1000 W for 420 seconds, 3500 W for 240 seconds, and 4500 W for 900 seconds. The thermal regeneration of Example 4 was carried out in the same manner as in Example 3. The measurement results are shown in Table 1. It was confirmed that the iodine adsorption performance was restored to 600 mg / g.

[0068] [Example 5] Granular activated carbon (average particle size 37 μm, moisture content 10%, iodine adsorption capacity before regeneration 790 mg / g) that had adsorbed the same organic matter as the powdered activated carbon contained in the sample of Example 1 was used as a sample, and 50.73 g of the sample was spread inside a frame. Heat regeneration of Example 5 was carried out in the same manner as in Example 1, except that the microwave irradiation energy was changed to 1000 W for 150 seconds and 500 W for 900 seconds.

[0069] The sample after heat regeneration was recovered, and its weight and iodine adsorption capacity were measured. The measurement results are shown in Table 1. It was confirmed that the iodine adsorption capacity was restored to 900 mg / g.

[0070] Example 6 Microwave heating in Example 6 was carried out in the same manner as in Example 1, except that new powdered activated carbon (average particle size 34 μm) was used as the sample. The sample after heating was recovered, and its weight and iodine adsorption capacity were measured. The measurement results are shown in Table 1. The iodine adsorption capacity was 1000 mg / g for new powdered activated carbon, but improved to 1070 mg / g after heating. This is thought to be due to further development of micropores by microwave heating.

[0071] Comparative Example 1 A cylindrical rotating drum (φ200 mm, height 100 mm) simulating a rotary kiln heating furnace was installed in a microwave irradiation box (400 mm × 400 mm × 400 mm) at an angle of 45°C. 390.49 g of the same sample as in Example 1 was placed in this rotating drum. Nitrogen was purged into the microwave irradiation box at a flow rate of 10 L / min for 5 minutes, and then microwave heating regeneration was initiated while rotating the rotating drum at a rotation speed of 3 rpm.

[0072] The microwave irradiation energy was changed in sequence from 2000 W for 660 seconds, 1000 W for 60 seconds, and 1200 W for 210 seconds, while the temperature inside the rotating drum was maintained at about 500 to 600°C.

[0073] In this regeneration test, powder scattered along with the desorbed gas from the mixture of used activated carbon and diatomaceous earth, and the powdered carbon adhered to the inside of the microwave irradiation box, resulting in scattered deposition. After thermal regeneration, the samples were collected and their weight and iodine adsorption performance were measured. The measurement results are shown in Table 2. The iodine adsorption performance recovered to 530 mg / g. However, due to the influence of fine powder scattered along with the desorbed gas emitted from the rotating drum, it was confirmed that this was not practical for practical use.

[0074] Comparative Example 2 A microwave heating test for Comparative Example 2 was carried out in the same manner as in Example 1, except that the sample was a 40 g mixture of the diatomaceous earth used in precoat filtration and the material to be filtered (organic material), and microwave irradiation was performed at a constant irradiation energy of 1000 W. The sample ignited 470 seconds after the start of irradiation, and the test was discontinued.

[0075] A microwave heating test for Comparative Example 3 was carried out in the same manner as in Example 1, except that after irradiating with microwaves at 1000 W for 150 seconds, the irradiation energy was changed to 500 W. 200 seconds after the irradiation energy was changed to 500 W, the sample ignited, and the test was discontinued.

[0076]

[0077]

[0078] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the above-described embodiments. Furthermore, components from different embodiments may be appropriately combined.

[0079] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the spirit and scope of the present invention. This application is based on Japanese Patent Application No. 2023-188705, filed on November 2, 2023, and is incorporated by reference in its entirety.

[0080] REFERENCE SIGNS LIST 1 Activated carbon 2 Hopper 3 Plate 4 Conveyor section 5 Leveling plate 6 Heat treatment box 7 Microwave generator 8 Exhaust pipe 9 Propeller 10 Infrared camera 11 Microwave leakage prevention shutter 20 Control device

Claims

1. A method for regenerating activated carbon, comprising the steps of: placing activated carbon having an average particle size of 1 to 100 μm on a flat plate; and regenerating the activated carbon on the flat plate by microwave heating.

2. The method for regenerating activated carbon according to claim 1, wherein the plate is repeatedly moved forward and backward by a belt conveyor or a roller conveyor while the plate is being heated by microwaves.

3. The method for regenerating activated carbon according to claim 1, further comprising measuring the temperature of the activated carbon during microwave heating and controlling microwave irradiation energy based on the measurement result.

4. The method for regenerating activated carbon according to claim 1, wherein the activated carbon is heated by microwaves in a heat treatment box having an oxygen concentration of 2% or less.

5. The method for regenerating activated carbon according to claim 4, further comprising treating the exhaust gas from said heat treatment box and supplying the treated gas to said heat treatment box.

6. A method for regenerating activated carbon according to claim 1, wherein the height of the activated carbon on the flat plate is made uniform using a scraping plate before microwave heating.

7. An activated carbon regeneration system comprising: a hopper that supplies activated carbon having an average particle size of 1 to 100 μm onto a flat plate; a leveling plate that adjusts the height of the activated carbon on the flat plate to a constant level; a transport unit that transports the flat plate on which the activated carbon is placed to a heat treatment box; and a microwave generator that irradiates microwaves into the heat treatment box.

8. The activated carbon regeneration system of claim 7, wherein the transport section has a belt conveyor or a roller conveyor, and repeatedly moves the flat plate on which the activated carbon is placed forward and backward within the heat treatment box during microwave irradiation.

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