JP2014018731A - Apparatus and method for regenerating used activated carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for regenerating activated carbon, in which used activated carbon, which is used for purifying a cleaning solvent and on which a contaminant is adsorbed, can be regenerated in high production efficiency and further in high energy efficiency.SOLUTION: The apparatus 1 for regenerating activated carbon includes: a hopper 2 into which the used activated carbon is thrown; a plurality of continuous heating furnaces 3 for separating and desorbing a solvent from the used activated carbon; a regeneration furnace 4 for regenerating the solvent-desorbed activated carbon; a solvent liquefaction recovery tank 5 for liquefying/recovering the solvent vapor to be generated from the plurality of continuous heating furnaces 3; and a hot air generator 6 so that the solvent is vaporized/separated stepwise from the activated carbon at different temperatures and then the adsorbed contaminant is removed therefrom to regenerate the activated carbon.

Description

  The present invention relates to a regeneration method and a regeneration apparatus for efficiently regenerating spent activated carbon containing contaminants used for regeneration of a cleaning solvent.

  Currently, cleaning solvents are used in a wide variety of industries, such as the metal industry, precision equipment industry, and dry cleaning industry, and the solvent is often purified and reused from an environmental and economic point of view. Activated carbon is often used as an agent.

  For example, in dry cleaning, chlorine-based or petroleum-based cleaning solvents are used as cleaning liquids. However, if this cleaning liquid is used repeatedly, the cleaning liquid deteriorates due to contaminants removed from the object to be cleaned at each cleaning. To go. A dry cleaning washing machine equipped with an activated carbon filter for adsorbing and removing the contaminants from the cleaning liquid is often used.

  In the activated carbon constituting the activated carbon filter, the adsorption performance gradually decreases with the amount of contaminant adsorbed from the cleaning liquid. When the amount of adsorption exceeds a certain amount, the adsorption capacity is drastically reduced, and it is no longer possible to stop the deterioration of the cleaning liquid. For this purpose, the activated carbon filter is periodically replaced to maintain the cleaning ability of the cleaning liquid. There has been proposed an invention in which activated carbon is taken out from a used activated carbon filter and repeatedly used through a regeneration process.

  The adsorption state of the cleaning solvent adsorbed on the activated carbon can be divided into a state where it is adsorbed on the surface of the activated carbon (hereinafter referred to as surface adsorption) and a state where it is adsorbed into the pores of the activated carbon (hereinafter referred to as pore adsorption). Broadly speaking, the energy required for solvent separation from activated carbon is more required for pore adsorption.

  Patent Document 1 discloses a batch-type regeneration method of used activated carbon using a dry cleaning solvent.

JP-A-7-256098

  As a conventional method for regenerating activated carbon, there is a method by solvent washing extraction, heat regeneration, and the like. For example, a method using a regeneration furnace at 800 ° C. to 1000 ° C. is generally known as heat regeneration. Spent activated carbon contains not only pollutants but also a lot of washing solvent (in the case of dry cleaning, usually 50 to 70% of the weight of the used activated carbon). The solvent is separated as a gas, and the liquefaction recovery apparatus for liquefying and recovering this gas tends to be enlarged. In addition, a large amount of heating energy for regeneration and cooling energy for recovery are required, and the equipment tends to increase in size.

  There is also known a method of combusting the separated solvent gas and reusing it as a heat energy source for regeneration. However, when the solvent gas is in a large amount, the combustion energy greatly exceeds the heat energy required for regeneration. Since a large amount of solvent containing pollutants comes out, the temperature rises too much and temperature control becomes difficult. For this reason, the regeneration amount per hour of the used activated carbon has to be reduced, so that the regeneration capability is low. Or the generated heat energy must be discarded.

  The method of Patent Document 1 is a batch method, and as pointed out above, there is a problem of low production efficiency.

  An object of the present invention is to provide an activated carbon regenerator that can regenerate spent activated carbon adsorbing contaminants used for cleaning cleaning solvents with high production efficiency and energy efficiency.

  The present inventor separates heating (recovery of solvent) and regeneration (removal of contaminants) to reduce the amount of solvent in the activated carbon, and then regenerates (activation process), thereby processing per unit time. Focusing on the fact that the amount can be increased, the present invention has been achieved.

  That is, in order to solve the above-mentioned problem, the activated carbon regenerator 1 according to claim 1 includes a plurality of continuous heating furnaces 3 each capable of temperature setting for separating and desorbing the solvent from the used activated carbon in a continuous manner, and a solvent And a regeneration furnace 4 for regenerating the activated carbon from which the carbon is separated. Since the activated carbon regeneration apparatus 1 according to claim 1 includes a plurality of heating furnaces for separating the solvent, it is possible to set solvent separation conditions for each heating furnace, and to perform continuous separation stepwise, selectively and efficiently. It is a feature that can be done. This is because the solvent adsorbed on the activated carbon can be separated at a temperature close to the vaporization temperature of the solvent, but desorption from the pores of the solvent adsorbed on the activated carbon requires a temperature higher than the vaporization temperature. is there. Therefore, when performing the separation of the solvent with one apparatus, the temperature necessary for the separation of the pore-adsorbing solvent must be used, and the surface-adsorbing solvent and the pore-adsorbing solvent are simultaneously used. A large amount of solvent gas is generated.

  Here, “separation of solvent” means that the surface adsorbed solvent is separated from the activated carbon. Usually, it can be processed at the vaporization temperature of the solvent. “Desorbing the solvent” means desorbing the pore-adsorbed solvent from the activated carbon. The desorption temperature is usually higher than the vaporization temperature of the solvent. The regeneration sequence of the activated carbon first separates the solvent, and then desorbs the solvent in a higher temperature range. At the desorption temperature, thermal decomposition of contaminants adsorbed on the activated carbon also occurs. The thermal decomposition residue of the pollutant becomes carbon and remains in the activated carbon pores. The pyrolysis residue is gasified and removed by an activation reaction in a regeneration furnace following the heating furnace. In this way, the activated carbon can be regenerated.

  The solvent liquefaction recovery tank 5 according to claim 2 includes a cooling device 5a for cooling and liquefying the solvent gas separated in the continuous heating furnace 3, and a solvent recovery tank 5b.

  The activated carbon regeneration method according to claim 3, wherein the activated carbon is continuously treated at a plurality of temperature zones to separate and desorb the solvent adsorbed on the surface and the solvent adsorbed on the pores. It has a heating process and the regeneration process which reproduces | regenerates solvent-separated activated carbon, It is characterized by the above-mentioned.

  5. The activated carbon regeneration method according to claim 4, wherein the separated and desorbed solvent gas is liquefied and recovered.

  ADVANTAGE OF THE INVENTION According to this invention, the activated carbon reproduction | regeneration apparatus which can reproduce | regenerate the used activated carbon containing a washing | cleaning solvent and a contaminant efficiently, and can collect | recover and reuse the isolate | separated and desorbed solvent can be provided.

It is a block diagram of activated carbon reproduction device 1 of Embodiment 1 of the present invention. It is a block diagram of the activated carbon reproduction | regeneration apparatus 101 of Embodiment 2 of this invention. 1 is an iodine adsorption isotherm of activated carbon regenerated according to the present invention. 1 is a methylene blue adsorption isotherm of activated carbon regenerated according to the present invention.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the activated carbon regenerator 1 of Embodiment 1 includes a hopper 2 for introducing used activated carbon, a continuous heating furnace 3 composed of a plurality of components for separating and desorbing a solvent from the used activated carbon, and a solvent desorbed A regeneration furnace 4 for regenerating activated carbon, a solvent liquefaction recovery tank 5 for liquefying and recovering solvent gas generated from the continuous heating furnace 3, and a hot air generator 6 are provided.

  The continuous heating furnace 3 is a part where the cleaning solvent is separated and desorbed from the used activated carbon, and the carbonization of the pollutants is performed. The continuous heating furnace in one section includes a heating furnace body 3a, a heating chamber 3b, and a discharge port. 3c. FIG. 1 shows a two-section continuous heating furnace, but there is no problem even if three or more sections are provided. Hot air having a temperature higher than that of the hot air generating furnace 6 is supplied to the heating chamber 3b to indirectly heat the processed material in the heating furnace body 3a. Moreover, the heating furnace body 3a is rotatably supported. The furnace temperature at the front of the heating furnace body 3a is set to a temperature close to the solvent vaporization temperature, and the solvent adsorbed on the surface of the activated carbon is separated. The furnace temperature at the rear of the heating furnace 3a is set to a temperature higher than the solvent vaporization temperature, and the solvent adsorbed on the pores is desorbed, and at the same time, the contaminants adsorbed on the activated carbon are thermally decomposed. Due to pyrolysis, the contaminants remain as carbon in the pores. After being processed in the continuous heating furnace, the used activated carbon is transferred to the regeneration furnace 4.

  The regeneration furnace 4 is a part that regenerates the used activated carbon from which the solvent is separated and desorbed, and includes a regeneration furnace body 4a, a regeneration furnace heating chamber 4b, and a discharge port 4c. High-temperature hot air is supplied to the regenerative furnace heating chamber 4b from the hot air generating furnace 6 to indirectly heat the processed material in the regenerative furnace main body 4a. The regenerative furnace main body 4a is rotatably supported. The activation gas injection pipe 4d is connected to the regeneration furnace body 4a. Thereby, a set amount of activation gas is quantitatively sent to the regeneration furnace body 4a via the activation gas injection pipe 4d. As the activation gas, water vapor, carbon dioxide, oxygen, air, or a mixed gas of two or more thereof can be used.

  The contaminant carbonized by heat treatment in the heating furnace 3a reacts with the activation gas in the regeneration furnace body 4a to become carbon monoxide or carbon dioxide, which is gasified and separated from the activated carbon, and is activated from the regeneration furnace body 4a. It is sent to the hot air generating furnace 6 via the transfer pipe 4e.

  The solvent liquefaction recovery tank 5 includes a cooling device 5a, a solvent recovery tank 5b, and an auxiliary burner fuel transfer pipe 5c. Each discharge port 3c of the heating furnace 3 is provided with a transfer pipe 3d for solvent gas generated in the heating furnace, and is connected to the solvent liquefaction recovery tank 5. The solvent gas generated in the heating furnace body 3a is set to be sent to the solvent recovery tank 5b via the discharge port 3c, the solvent gas transfer pipe 3d, and the cooling device 5a. In addition, the apparatus which cools solvent gas is not specified, such as a heat exchanger and a cooler, and there is no problem even if it uses which apparatus.

  Further, in FIG. 1, the solvent liquefaction recovery tank 5 is attached to each heating furnace 3a, but is not specified. For example, although details will be described in the second embodiment, the solvent gases of the two heating furnaces are collectively shown. The method of cooling recovery and the combination of cooling recovery of solvent gas in three or more sections of the heating furnace can be selected depending on the nature, amount, and recycling method of the solvent gas.

  The solvent recovered in the solvent recovery tank 5b is reused according to the performance of the solvent. As shown in the drawing, as necessary, the fuel is transferred as fuel for the auxiliary burner 6a of the hot air generating furnace 6 through the auxiliary burner fuel transfer pipe 5c and can also be used as a heat energy source.

  The hot air generating furnace 6 completely burns the supplied activated product gas, and the gas temperature in the hot air generating furnace 6 is set to an auxiliary burner 6a mainly composed of fuel supplied from the solvent recovery tank 5b. It is adjusted by the amount of air injected from the combustion air injection pipe 6b. The hot air generating furnace 6 and the regenerative furnace heating chamber 4b are connected via a hot air pipe 7, and the hot air generated in the hot air generating furnace 6 is sent to the regenerative furnace heating chamber 4b via the hot air pipe 7, and the regenerative furnace main body. It is configured to keep the temperature of 4a at a predetermined temperature. The regenerative furnace heating chamber 4b and the heating furnace heating chamber 3b are connected via a hot air pipe 7, so that the hot air moves from the regenerative furnace heating chamber 4b to the heating furnace heating chamber 3b to keep the heating furnace main body 3a at a predetermined temperature. Is set. Used activated carbon, solvent-separated activated carbon, regenerated activated carbon, and the like have a structure that does not come into direct contact with hot air supplied from the hot air generating furnace 6.

  Next, the activated carbon regeneration method by the activated carbon regeneration apparatus 1 of the embodiment of the present invention will be described. The used activated carbon carried into the hopper 2 is continuously supplied to the heating furnace body 3a. A heating temperature is set for each of a plurality of continuous heating furnace bodies 3a. For example, in the case of activated carbon used for regeneration of petroleum solvent for dry cleaning, when the heating furnace is divided into two sections, the temperature of the first heating furnace main body (the heating furnace main body 3a on the left side in FIG. 1), that is, the first heating. The temperature is adjusted to an arbitrary temperature of 100 to 300 ° C., preferably 200 to 300 ° C., and the temperature of the second heating furnace body (the heating furnace body 3a on the right side in FIG. 1), that is, the second heating temperature is 300 to 500 ° C. Desirably, the temperature is adjusted to an arbitrary temperature of 400 to 450 ° C. The solvent having the surface adsorbed at the first heating temperature and the solvent having the pores adsorbed at the second heating temperature are separated and desorbed. In the second heating furnace main body 3a, the thermal decomposition of the contaminants adsorbed on the surface and the pores also occurs, and not only the solvent but also the contaminants are thermally decomposed. The solvent-separated activated carbon treated in the heating furnace is transferred to the regeneration furnace 4. The steps so far are performed continuously.

  The regeneration furnace body 4a is heated by the regeneration furnace heating chamber 4b, and the temperature inside the regeneration furnace body 4a is adjusted to an arbitrary temperature of 600 to 1,500 ° C., desirably 800 to 1,000 ° C. One or more kinds of activation gases such as water vapor, carbon dioxide, air, and oxygen are supplied to the regeneration furnace body 4a through the activation gas injection pipe 4d, and the activation reaction starts. The regeneration furnace body 4a rotates in order to perform uniform regeneration on the supplied solvent-separated activated carbon. The activation time is 5 to 2400 minutes, preferably 5 to 600 minutes, and the activation time can be changed depending on the amount of the contaminant adsorbed by the used activated carbon. The adsorption performance of the regenerated activated carbon can be adjusted by the type of the activated gas, the activated gas supply amount, the temperature inside the regeneration furnace main body 4a, the activation time, and the like. Thereby, the thermal decomposition residue of the pollutant remaining in the pores of the activated carbon can also be removed, and the regeneration ability can be greatly enhanced. The regeneration furnace may be a continuous type or a batch type depending on the processing time.

  The solvent gas separated and desorbed in each heating furnace body 3a is cooled via the solvent gas transfer pipe 3d via the cooling device 5a and sent to the solvent recovery tank 5b. From the first heating furnace body 3a, pure solvent gas is received and liquefied and recovered, and from the second heating furnace body 3a, solvent gas containing pyrolysis gas of pollutants is received and liquefied and recovered. This also takes into account the convenience of use. The method for cooling the solvent gas has no problem no matter which cooling method is used, such as a method using a heat exchanger or a method using a cooler.

  The product gas containing carbon monoxide and hydrogen gas generated by the activation reaction when steam is used as the activation gas is sent from the regeneration furnace body 4a to the hot air generation furnace 6 via the activation product gas transfer pipe 4e.

  The activated product gas is completely burned in the hot air generating furnace 6, adjusted in temperature by the amount of air injected from the auxiliary burner 6 a or the combustion air injection pipe 6 b, etc., and then regenerated through the hot air pipe 7. It is sent to the furnace heating chamber 4b, and the temperature of the regeneration furnace body 4a is kept at a predetermined temperature. Next, the hot air is sequentially sent from the regenerative furnace heating chamber 4b to the regenerative furnace heating chamber 3b through the hot air pipe 7 to keep the regenerative furnace main body 3a at a predetermined temperature. Thereafter, the hot air is discharged from the exhaust pipe 3e. The liquefied solvent from the auxiliary burner fuel transfer pipe 5c is used as a main heat source, and the activated product gas from the activated product gas transfer pipe 4e is used as a secondary heat source.

  As described above, according to the first embodiment described above, the solvent having high combustion heat is separated from the entire apparatus by separating and desorbing the used activated carbon containing the cleaning solvent and the contaminants in stages by the plurality of heating furnaces 3a. can do. In the conventional activated carbon regenerator that burns all the solvent separated from the used activated carbon, it is necessary to adjust the amount of used activated carbon per unit time to control the temperature of the device. Was bad. According to the first embodiment, since the solvent is not liquefied and separated and burned, the input amount of used activated carbon per unit time can be increased. Therefore, the apparatus can be reduced in size and temperature control can be facilitated, and the used activated carbon can be efficiently regenerated.

  In addition, while the recovered solvent can be reused according to performance, a part of the solvent can be used as a fuel of thermal energy together with the activation product gas, so that energy efficiency can be improved.

  The present invention is not limited to the above-described embodiment, and modifications and the like can be made without departing from the technical idea of the present invention. It is included in the technical scope of the invention. For example, hot air is supplied in series from the regenerative furnace heating chamber 4b to the heating furnace heating chamber 3b, but hot air from the hot air generating furnace 6 is supplied in parallel to the regenerative furnace heating chamber 4b and the heating furnace heating chamber 3b. May be. Further, for example, the regenerative furnace main body 4a is indirectly heated and kept in the regenerative furnace heating chamber 4b, but the activated product gas generated in the regenerative furnace main body 4a is changed to a controlled amount of air in the regenerative furnace main body 4a. By introducing, the processed material in the regenerative furnace main body 4a may be heated directly or may be used in combination. In the first embodiment, the liquefied solvents respectively flowing out from the solvent recovery tank 5b are joined and reused, but can be reused for different purposes while being separated.

  An embodiment of an activated carbon regeneration method using spent activated carbon used in petroleum solvent-based cleaning provided by a cleaning company will be described.

  (Example 1) The used activated carbon was subjected to a first heat treatment at 210 ° C for 150 minutes, a second heat treatment at 550 ° C for 30 minutes, and a reactivation treatment at 850 ° C for 80 minutes. Regenerated product A was obtained as the first and second separation solvents and the final processed product, each of which was cooled by the solvent gas generated in the first and second heat treatments.

  (Example 2) The used activated carbon was subjected to a first heat treatment at 210 ° C for 150 minutes, a second heat treatment at 550 ° C for 30 minutes, and a reactivation treatment at 850 ° C for 150 minutes. Recycled material B was obtained as the first and second separation solvents and the final treated product, each of which was obtained by cooling the solvent gas generated in the first and second heat treatments.

(Comparative Example 1) The used activated carbon was subjected to a first heat treatment at 210 ° C for 150 minutes and a second heat treatment at 550 ° C for 30 minutes. Regenerated product C was obtained as the first and second separation solvents and the final treated product, each of which was cooled by the solvent gas generated in the first and second heat treatments.

(Comparative Example 2) 550 ° C. × 120 minutes in a method in which used activated carbon is burned with a solvent gas separated by the method described in [0008], which is a general method, and reused as a thermal energy source for regeneration. I did it. All of the desorbed gas was used for combustion and there was no solvent recovery, and a regenerated product D was obtained as a final processed product.

The unused activated carbon, regenerated material A, regenerated material B, regenerated material C and regenerated material D were subjected to iodine adsorption test and methylene blue adsorption test according to JIS K1474, and the adsorption isotherms shown in FIGS. 3 and 4 were prepared. . The amount of adsorption determined from each adsorption isotherm is summarized in Table 1. Since the regenerated product C was only solvent separation / desorption and carbonization, the adsorption ability was low. On the other hand, the regenerated product A and the regenerated product B have higher adsorption capacity than the regenerated product D, which is a conventional method, because the reactivation is performed as solvent separation / desorption, carbonization and regeneration treatment. Furthermore, it became clear from the results of the regenerated product A and the regenerated product B that the adsorption capacity of the regenerated product can be adjusted by changing the reactivation conditions.
(Table 1) Adsorption performance table

  The activated carbon regenerator 101 of the second embodiment has substantially the same configuration as the activated carbon regenerator 1 of the first embodiment, but has a single solvent liquefaction recovery tank 105 that recovers and liquefies the solvent gas generated from the continuous heating furnace 3. It is different in a point and a difference is demonstrated. In the second embodiment, elements that are the same as those in the first embodiment are illustrated as 100s and the description is incorporated. As a result, the activated carbon regenerator 101 is simplified, while the two cooling devices 5a and the two solvent recovery tanks 5b can be separately recovered in two systems according to the performance of the solvent as in the first embodiment. However, it is different in that it is simply recovered in one system by the cooling device 105a and the solvent recovery tank 105b. The first and second embodiments may be appropriately selected according to various circumstances such as the use.

1,101 Activated carbon regenerating apparatus 4e Activation product gas transfer pipe 2 Hopper 5,105 Solvent liquefaction recovery tank 3 Continuous heating furnace 5a Cooling apparatus 3a Heating furnace body 5b Solvent recovery tank 3b Heating furnace heating chamber 5c Auxiliary burner fuel transfer pipe 3c Exhaust Outlet 6 Hot-air generating furnace 3d Solvent gas transfer pipe 6a Auxiliary burner 3e Exhaust pipe 6b Combustion air injection pipe 4 Regeneration furnace 7 Hot-air pipe 4a Regeneration furnace body 4b Regeneration furnace heating chamber 4c Exhaust port 4d Activation gas injection pipe

Claims (4)

  A plurality of continuous heating furnaces for separating and desorbing the solvent from the used activated carbon at different processing temperatures, and a regeneration furnace for regenerating the used activated carbon by removing adsorbed contaminants from the used activated carbon treated in the continuous heating furnace And an activated carbon regenerator.   A plurality of solvent liquefaction recovery tanks for separately liquefying and recovering the solvent gas separated and desorbed from the used activated carbon in the continuous heating furnace, or one solvent liquefaction recovery tank for simultaneously recovering the solvent gas The activated carbon regenerator according to claim 1.   A plurality of continuous heating steps for continuously separating and desorbing the solvent from the used activated carbon in different treatment temperature zones, and removing the adsorbed contaminants from the used activated carbon treated in the continuous heating step, And a regeneration step for regenerating the activated carbon regeneration method. The activated carbon regeneration method according to claim 3, further comprising a plurality of or one solvent liquefaction recovery step of liquefying and recovering the solvent gas separated and desorbed from the used activated carbon in the continuous heating furnace and separately or simultaneously. .

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