Reactivation method for used adsorbent, reactivation device, reactivated adsorbent, oil regeneration device including adsorption processing unit packed with reactivated adsorbent, and oil regeneration device equipped with reactivation device

Abstract

In order to provide a method for reactivating a used adsorbent without a high-temperature process, a reactivation device, a reactivated adsorbent, an oil regeneration device including an adsorption processing unit packed with a reactivated adsorbent, and an oil regeneration device equipped with a reactivation device, the present invention is configured as follows.　Provided are: a method for reactivating a used adsorbent, the method comprising a step for stirring the used adsorbent and a nonpolar solvent, a step for separating the adsorbent from the nonpolar solvent, a step for stirring the separated adsorbent and an alkali solvent, and a step for separating the adsorbent from the alkali solvent; a reactivation device; a reactivated adsorbent; an oil regeneration device including an adsorption processing unit packed with a reactivated adsorbent; and an oil regeneration device equipped with a reactivation device.

Description

Method for reactivating used adsorbent, reactivation device, reactivated adsorbent, oil regeneration device having an adsorption treatment section filled with reactivated adsorbent, and oil regeneration device equipped with a reactivation device

[0001] The present invention relates to a method for reactivating a used adsorbent, a reactivation device, a reactivated adsorbent, an oil regeneration device having an adsorption treatment section filled with the reactivated adsorbent, and an oil regeneration device equipped with a reactivation device.

[0002] To protect the global environment, ２ It is necessary to reduce emissions and waste. As part of this effort, we will reduce the amount of used oil disposed of and reduce the CO2 emissions associated with its incineration. ２ There is a demand to reduce this. To achieve this, it is effective to restore the functions of used oil and reuse it. For example, insulating oil in transformers and lubricating oil in compressors deteriorate over long periods of use and are usually discarded, but reusing these types of oil is expected to reduce the environmental impact. The total acid number is widely used as an indicator of oil deterioration. The total acid number is the number of milligrams of potassium hydroxide required to neutralize all acidic components contained in 1 gram of oil, and the higher the value, the more deteriorated the oil is.

[0003] Reducing the total acid number is an effective way to regenerate used oil, and adsorbents such as mineral adsorbents, synthetic adsorbents, and ion exchange resins are widely used. By adding an adsorbent to used oil and stirring it, acidic components such as free fatty acids in the oil are adsorbed onto the surface and pores of the adsorbent, reducing the total acid number.

[0004] Used adsorbents are often discarded because they accumulate acidic components such as free fatty acids, reducing their oil regeneration capacity compared to new adsorbents. To reduce the environmental impact, it is desirable to restore the oil regeneration capacity of used adsorbents (hereafter referred to as reactivation) and reuse them, just like used oil.

[0005] Heat treatment is commonly used to reactivate adsorbents. Patent Document 1 discloses a method for reactivating a zeolite adsorbent that removes sulfur from hydrocarbon oils. The zeolite adsorbent is heat-treated at 300°C to 800°C in an oxygen-free air stream, and then heat-treated at 300°C to 800°C in an oxygen-containing air stream, thereby removing impurities such as carbon and sulfides that have accumulated on the adsorbent and reactivating the adsorbent.

[0006] JP 2010-221188 A

[0007] When reactivating adsorbents by heat treatment, the particles of the adsorbent aggregate during the heat treatment, reducing the specific surface area and the number of adsorption sites. This means that the reactivation of the adsorbent stops at a certain level and it may not be possible to reuse it for oil recovery. In addition, the high-temperature process requires high energy consumption, and the environmental impact may not be reduced compared to disposing of the adsorbent.

[0008] An object of the present invention is to provide a method for reactivating a used adsorbent without the need for a high-temperature process, a reactivation device, a reactivated adsorbent, an oil regeneration device having an adsorption treatment section filled with the reactivated adsorbent, and an oil regeneration device equipped with a reactivation device.

[0009] To achieve the above object, the present invention provides the following: a method for reactivating a used adsorbent, including a step of stirring the used adsorbent and a non-polar solvent, a step of separating the adsorbent from the non-polar solvent, a step of stirring the separated adsorbent and an alkaline solvent, and a step of separating the adsorbent from the alkaline solvent; a reactivation device; a reactivated adsorbent; an oil regeneration device having an adsorption treatment section filled with the reactivated adsorbent; and an oil regeneration device equipped with the reactivation device.

[0010] According to the present invention, it is possible to provide a method for reactivating a used adsorbent without the need for a high-temperature process, a reactivation device, a reactivated adsorbent, an oil regeneration device having an adsorption treatment section filled with the reactivated adsorbent, and an oil regeneration device equipped with a reactivation device.

[0011] Fig. 1 is a schematic diagram of a used adsorbent targeted by the present invention; Fig. 2 is a diagram showing an adsorbent reactivation device of one embodiment; Fig. 3 is a flowchart showing an adsorbent reactivation method of one embodiment; Fig. 4 is a diagram showing solvent types used in an adsorbent reactivation test; and Fig. 5 is a diagram showing experimental results of the reactivation degree of the adsorbent obtained in the reactivation test.

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments, and different embodiments may be combined with each other, and any modifications may be made within the scope that does not significantly impair the effects of the present invention.

[0013] Figure 1 is a schematic diagram of the adsorbent targeted by this invention. While adsorbents are often roughly spherical, which has the largest surface area, used adsorbents of various shapes other than spherical shapes can also be treated. A partial enlargement of the adsorbent is shown on the right side of Figure 1. The surface of the adsorbent has numerous pores, which increases the surface area and improves adsorption performance. However, if oil is adsorbed into these pores and fatty acids are trapped in the fine cracks around the pores, the adsorption performance cannot be restored unless the oil, fatty acids, etc. are removed from the used adsorbent, as shown in the lower right figure. Below, we will explain the device and method for removing oil, fatty acids, etc. from used adsorbent, as shown in the lower right figure.

[0014] Fig. 2 is a diagram showing an adsorbent reactivation apparatus 10 according to one embodiment. Fig. 3 is a flowchart showing an adsorbent reactivation method according to one embodiment. The adsorbent reactivation apparatus and method will be described below with reference to Figs. 2 and 3.

[0015] In step S21 of FIG. 3, the adsorbent and nonpolar solvent are introduced into the first treatment device (11a, also referred to as the first treatment device) of FIG. 2 and stirred to remove oil retained on the surface and in the pores of the adsorbent. There is no limit to the stirring time, but it is desirable to carry out the stirring for 30 minutes or more to remove the oil. Well-known techniques such as rotating a propeller-shaped stirring blade within the first treatment device (11a) can be used for stirring. To improve stirring efficiency, an ultrasonic irradiation mechanism for generating cavitation may be provided within the first treatment device (11a) as needed.

[0016] Next, in step S22 of FIG. 3, the adsorbent and nonpolar solvent are introduced into the first filtration device (12a, also referred to as the first filtration device) of FIG. 2, where they are separated by filtration. The method of introduction into the first filtration device (12a) involves transporting the mixture (slurry) of the adsorbent and nonpolar solvent in the first treatment device (11a) to the first filtration device (12a) via a flow path. If necessary, a pump may be used to shorten the time required to transport the mixture. In the first filtration device (12a), the adsorbent and nonpolar solvent are separated using a mesh. The separated nonpolar solvent is transported to a waste liquid treatment tank (not shown) via a flow path. The separated adsorbent remaining on the mesh is transported to a second treatment device (11b, also referred to as the second treatment device) by a hand mechanism (not shown) that grips and transports the mesh. Alternatively, the adsorbent may be vacuum-suctioned, and the sucked adsorbent may be transported to the second treatment device (11b) via a pipe.

[0017] Next, in step S23 of Fig. 3, the adsorbent and alkaline solvent are stirred in the second treatment device (11b) of Fig. 2 to remove acidic components such as free fatty acids that have accumulated on the surface and in the pores of the adsorbent. There is no limit to the stirring time, but it is desirable to carry out the stirring for 30 minutes or more to remove oil.

[0018] Next, in step S24 of FIG. 3, the adsorbent and alkaline solvent are introduced into the second filtration device (12b, also referred to as the second filtration device) of FIG. 2, where they are separated by filtration. Here, as with the first filtration device (12a), the adsorbent and alkaline solvent are separated using a mesh. The separated alkaline solvent is transported to a waste liquid treatment tank (not shown) via a flow path. The separated, reactivated adsorbent remaining on the mesh is transported to the adsorbent recovery section 13 of FIG. 2 and stored in step S25 of FIG. 3. The reactivated adsorbent can be reused for oil regeneration by filling it into the adsorption treatment section of the oil regeneration device.

[0019] The first treatment device (11a), second treatment device (11b), first filtration device (12a), and second filtration device (12b) in Figure 2 are controlled by a control device 14 (the dashed lines in Figure 1 indicate the control). The first filtration device (12a) and second filtration device (12b) are devices that physically separate the adsorbent and the liquid component using a filter, mesh, or the like, and there are cases where control by the control device 14 is not necessary. However, when a mechanism (not shown) for optically monitoring the clogging state of the filter or mesh is provided, or when a suction mechanism (not shown) for suctioning liquid from the downstream of the filter or mesh to accelerate separation is provided, the control device 14 can be configured to control these mechanisms.

[0020] In the above embodiment, the alkaline solvent in step S23 may be changed to a mixed solvent of an alkaline solvent and an alcohol, or the stirring treatment may be performed in an alkaline solvent and then in an alcohol solvent.

[0021] By using alcohol, fatty acid salts deposited on the surface and in the pores of the adsorbent can be removed, thereby improving the effect of reactivating the adsorbent.

[0022] Furthermore, if the removal of oil from the adsorbent in step S21 is insufficient, the alkaline solvent and oil may become suspended in step S23, making it impossible to reactivate the adsorbent. As a preventative measure, the second treatment device (11b) in Figure 2 may be equipped with a mechanism 15 for measuring the turbidity of the solvent, such as a turbidimeter, and the control device 14 may control the second treatment device (11b) to continue stirring until the turbidity becomes equal to or less than a predetermined value.

[0023] The adsorbent can be made of a weakly basic to basic material. The pH value of the adsorbent is preferably 7.5 to 11. The pH value can be measured, for example, by using a pH meter on pure water in which the adsorbent is dispersed at 5 wt%. The type of adsorbent that can be used is preferably, for example, silica-based, magnesium-based, silica-magnesia-based (magnesium silicate-based) adsorbents whose main components are silica and magnesium oxide, or mineral-based adsorbents.

[0024] The shape of the adsorbent is not particularly limited, but is preferably spherical. The average particle size is, for example, from 10 μm to 2000 μm, more preferably from 50 μm to 500 μm.

[0025] Examples of oils that can be regenerated using the adsorbent include ester oils, ether oils, vegetable oils, and mineral oils. The regeneration effect of the present invention is particularly high for oils that contain carbon and oxygen in their molecular structure. Specifically, these oils include ester oils, vegetable oils, and ether oils.

[0026] The non-polar solvent used in the first treatment device (11a) may be, for example, hexane, toluene, cyclohexane, benzene, or a mixture of two or more of these.

[0027] The alkaline solvent used in the second treatment device (11b) is preferably more basic than the adsorbent to be treated, such as an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, an aqueous solution of calcium hydroxide, or a mixture of two or more of these.

[0028] The alcohol solvent used in the second treatment device (11b) may be methanol, ethanol, propanol, butanol or a mixture of two or more of these.

[0029] The mixed solvent of alkali and alcohol used in the second treatment device (11b) may be a mixture of two or more of the above-mentioned solvents.

[0030] The reason why the apparatus and method shown in Figures 2 and 3 are effective for reactivating adsorbents is explained below. Acidic components such as free fatty acids accumulate on the surface and pores of adsorbents used for oil reclamation. This reduces the adsorption sites of the adsorbent, making it difficult to reuse it for oil reclamation. Therefore, removing the deposits from the adsorption sites is effective for reactivating adsorbents.

[0031] The inventors conducted numerous reactivation tests on used adsorbents and found that multi-stage treatment using multiple solvents can remove deposits from adsorption sites and is effective in reactivating adsorbents. Specifically, in the first stage of solvent treatment, agitating the adsorbent in a nonpolar solvent can remove oil from the surface and pores of the adsorbent. Furthermore, in the second stage of solvent treatment, agitating the adsorbent in an alkaline solvent can remove acidic components such as free fatty acids deposited on the adsorption sites and restore the surface pH of the adsorbent to basicity. In this case, the alkaline solvent preferably has a higher basicity than the surface pH of the adsorbent. Furthermore, they found that fatty acid salts can be removed by using a polar alcohol solvent in the second stage of solvent treatment. It was revealed that such multi-stage treatment can reactivate adsorbents.

[0032] Furthermore, as will be described later in the Examples, it was confirmed that the adsorbent could not be sufficiently reactivated by a single-stage treatment using a non-polar solvent, an alkaline solvent, etc. In particular, it was confirmed that aqueous solutions such as alkaline solvents were insufficient in reactivation because they were suspended in the oil retained in the adsorbent.

[0033] Patent Document 1 discloses the reactivation of adsorbents by heat treatment. However, when applied to the used adsorbents targeted by the present invention, the adsorbent particles aggregate, reducing the specific surface area of ​​the adsorbent. This reduces the number of adsorption sites, resulting in insufficient reactivation of the adsorbent and making it impossible to reuse it for oil recovery. Furthermore, heat treatment consumes a lot of energy, so it may not be effective in reducing environmental impact.

[0034] To address these issues, the multi-stage treatment using multiple solvents of the present invention can effectively reactivate the adsorbent and contributes to energy savings because it does not require a high-temperature process.

[0035] The configuration of the reactivation device according to the present invention can be easily confirmed by visual inspection or by disassembling the device, etc. The type of solvent used can be easily confirmed by chemical analysis such as infrared spectroscopy or gas chromatography mass spectrometry.

[0036] The following shows the results of verifying the effectiveness of the reactivation device 10 through adsorbent reactivation tests. In the studies of Examples 1 to 5 and Comparative Examples 1 to 6, a silica-magnesia adsorbent was used as a representative example of the adsorbent. In these tests, a silica-magnesia adsorbent that had previously been used in the regeneration treatment of ester oil was used. The silica-magnesia adsorbent before the regeneration treatment of ester oil had an average particle size of 150 μm and a pH value of 9.1.

[0037] The solvent types are shown in Figure 4. The primary solvent is the solvent used in the first treatment device (11a), and the secondary solvent is the solvent used in the second treatment device (11b).

[0038] In Examples 1 to 4, hexane or toluene was used as the primary solvent, and a 1M aqueous sodium hydroxide solution or a mixture of 1M aqueous sodium hydroxide and ethanol was used as the secondary solvent. The primary solvent and adsorbent were introduced into a first treatment device (11a) and stirred at a stirring speed of 1000 rpm for 30 minutes. The primary solvent and adsorbent were then separated by suction filtration in a filtration device (12a). Next, the secondary solvent and adsorbent were introduced into a second treatment device (11b) and stirred at a stirring speed of 1000 rpm for 30 minutes. The secondary solvent and adsorbent were then separated by suction filtration in a filtration device (12b). The adsorbent was then recovered in an adsorbent recovery section 13.

[0039] In Example 5, hexane was used as the primary solvent, and 1M aqueous sodium hydroxide and ethanol were used as the secondary solvent. Hexane and the adsorbent were introduced into the first treatment device (11a) and stirred at a stirring speed of 1000 rpm for 30 minutes. The primary solvent and the adsorbent were then separated by suction filtration in the first filtration device (12a). Next, the 1M aqueous sodium hydroxide and the adsorbent were introduced into the second treatment device (11b) and stirred at a stirring speed of 1000 rpm for 15 minutes. Furthermore, ethanol was added to the second treatment device (11b) and stirred at a stirring speed of 1000 rpm for 15 minutes. The secondary solvent and the adsorbent were then separated by suction filtration in the second filtration device (12b). The adsorbent was then recovered in the adsorbent recovery section 13.

[0040] In Comparative Example 1, for comparison with the Examples, solvent treatment of the adsorbent was not performed. In Comparative Examples 2 to 6, water, hexane, acetone, ethanol, or 1 M aqueous sodium hydroxide solution was used as the primary solvent. The primary solvent and adsorbent were introduced into the first treatment device (11a) and stirred at a stirring speed of 1000 rpm for 30 minutes. Thereafter, the primary solvent and adsorbent were separated by suction filtration in the first filtration device (12a). A single-stage solvent treatment was performed without using a secondary solvent, and the adsorbent was recovered in the adsorbent recovery section 13.

[0041] The reactivation effect of the adsorbents in Examples 1 to 5 and Comparative Examples 1 to 6 was confirmed as follows. Degraded ester oil with a total acid number of 9 mg KOH / g was placed in an adsorption treatment unit filled with each adsorbent and stirred at a stirring speed of 1,000 rpm for 30 minutes. The adsorbent and the ester oil were then separated by suction filtration, and the ester oil was recovered. The reactivation degree of each adsorbent was evaluated using the following formula: Reactivation degree = (total acid number reduction value by reactivated adsorbent) / (total acid number reduction value by new adsorbent) * 100. Here, the total acid number reduction value by a new adsorbent refers to the amount of reduction in the total acid number of the degraded ester oil (mg KOH / g) by a new silica-magnesia adsorbent, and the total acid number reduction by a reactivated adsorbent refers to the amount of reduction in the total acid number of the degraded ester oil (mg KOH / g) by the silica-magnesia adsorbent treated in the Examples or Comparative Examples.

[0042] The reactivation degrees of Examples 1 to 5 and Comparative Examples 1 to 6 obtained by the adsorbent reactivation test are shown in Figure 5. In Comparative Example 1, the reactivation degree was as low as 18%, indicating a low reactivation effect for the adsorbent. Furthermore, even in Comparative Examples 2 to 6 where treatment was performed with a single solvent, the reactivation degree was 50% or less, indicating that a sufficient reactivation effect was not obtained.

[0043] On the other hand, the reactivation degree exceeded 80% in Examples 1 and 2. Furthermore, in Examples 3 to 5, in which alcohol was used in combination as the secondary solvent, the reactivation degree was 100% or more, and it was confirmed that the oil regeneration ability was higher than that of a new adsorbent.

[0044] From the results of the reactivation test described above, it was confirmed that multi-stage solvent treatment using the reactivation device 10, which uses a non-polar solvent as the primary solvent and an alkaline solvent or alcohol as the secondary solvent, can reactivate used adsorbent and enable it to be reused for oil regeneration.

[0045] Therefore, it is possible to provide an apparatus and method for reactivating a used adsorbent without a high-temperature process by a multi-stage treatment using multiple solvents, a reactivated adsorbent, an oil regeneration apparatus having an adsorption treatment section filled with the reactivated adsorbent, and an oil regeneration apparatus equipped with such a reactivation apparatus. This reduces the amount of oil and adsorbent waste and also reduces CO2 emissions during the waste incineration process. ２ This reduces the environmental impact.

[0046] 10... reactivation device, 11a... first treatment device, 11b... second treatment device, 12a... first filtration device, 12b... second filtration device, 13... adsorbent recovery section.

Claims

1. A method for reactivating a used adsorbent, comprising the steps of: stirring a used adsorbent and a non-polar solvent; separating the adsorbent from the non-polar solvent; stirring the separated adsorbent and an alkaline solvent; and separating the adsorbent from the alkaline solvent.

2. A method for reactivating a used adsorbent according to claim 1, characterized in that in the step of stirring the separated adsorbent and the alkaline solvent, a mixed solution of the alkaline solvent and an alcohol solvent is used.

3. A method for reactivating a used adsorbent according to claim 1, characterized in that after the step of stirring the separated adsorbent and the alkaline solvent, a step of stirring the adsorbent and an alcohol solvent is carried out.

4. A method for reactivating a used adsorbent according to claim 1, characterized in that the adsorbent is an adsorbent whose main components are silica and magnesium oxide.

5. A method for reactivating a used adsorbent according to claim 1, wherein the non-polar solvent contains at least one of hexane, toluene, cyclohexane, and benzene.

6. A method for reactivating a used adsorbent according to claim 1, characterized in that the alkaline solvent contains at least one of an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, and an aqueous solution of calcium hydroxide.

7. A method for reactivating a used adsorbent according to claim 2, wherein the alcohol solvent contains at least one of methanol, ethanol, propanol, and butanol.

8. A method for reactivating a used adsorbent according to claim 1, characterized in that the molecular structure of the oil adsorbed by the used adsorbent contains carbon and oxygen.

9. A method for reactivating a used adsorbent according to claim 1, characterized in that the oil adsorbed by the used adsorbent has a base oil of either ester oil or vegetable oil.

10. A method for reactivating a used adsorbent according to claim 1, characterized in that the shape of the used adsorbent is mainly approximately spherical.

11. A method for reactivating a used adsorbent according to claim 1, characterized in that the adsorbent has a pH value of 7.5 to 11.

12. A reactivation apparatus for a used adsorbent, comprising: a first treatment device for stirring a used adsorbent and a non-polar solvent; a first filtration device for separating the mixture in the first treatment device into the adsorbent and a liquid component; a second treatment device for stirring the adsorbent and an alkaline solvent separated by the first filtration device; and a second filtration device for separating the mixture in the second treatment device into the adsorbent and a liquid component.

13. A reactivation apparatus for used adsorbent according to claim 12, characterized in that in the second treatment device, the adsorbent separated in the first filtration device is stirred with a mixture of an alkaline solvent and an alcohol solvent.

14. The reactivation apparatus for used adsorbent according to claim 12 or 13, characterized in that it is provided with a turbidity meter for measuring the turbidity of the solvent in the second treatment device.

15. An adsorbent reactivated by the method for reactivating a used adsorbent according to any one of claims 1 to 11.

16. An oil regeneration device characterized by having an adsorption treatment section filled with adsorbent reactivated by the method for reactivating used adsorbent described in any one of claims 1 to 11.

17. An oil regeneration device comprising the device for reactivating used adsorbent according to claim 12 or 13.

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