METHOD OF USING MACHINE OIL, MACHINE OIL REGENERATION SYSTEM, AND METHOD OF ADDING MACHINE OIL REGENERATION UNIT

TECHNICAL FIELD

[0001]The present disclosure relates to a method of using machine oil, a machine oil regeneration system, and a method of adding a machine oil regeneration unit.

[0002]The present application claims priority based on Japanese Patent Application No. 2023-107817 filed on Jun. 30, 2023, the entire content of which is incorporated herein by reference.

BACKGROUND ART

[0003]Patent Document 1 describes a method for regenerating used insulating oil. Specifically, regenerated insulating oil is obtained by bringing an adsorbent having one or more of plaster, diatomite, bentonite, or marine silt into contact with used insulating oil to adsorb degraded components in the insulating oil onto the adsorbent, then removing the adsorbent from the insulating oil, and adding an antioxidant to the insulating oil.

CITATION LIST

Patent Literature

SUMMARY

Problems to be Solved

[0005]According to the method of Patent Document 1, it is possible to regenerate insulating oil, but it is not known whether it is possible to regenerate machine oil used for at least one of lubrication or power transmission.

[0006]An object of the present disclosure is to provide a method of using machine oil, a machine oil regeneration system, and a method of adding a machine oil regeneration unit that enable continuous use of the machine oil without disposing of it.

Solution to the Problems

[0007]A method of using machine oil according to at least one embodiment of the present disclosure is a method of using machine oil used for at least one of lubrication or power transmission, including: a first oxidation stability determination step of determining whether oxidation stability of an in-use or used machine oil is equal to or higher than a first specified level; a first continuous use step of continuing to use the in-use or used machine oil if it is determined that the oxidation stability is equal to or higher than the first specified level; an addition step of adding an additive for regeneration to the machine oil so that the oxidation stability is equal to or higher than a second specified level if it is determined that the oxidation stability is lower than the first specified level; and a second continuous use step of continuing to use the machine oil to which the additive has been added.

[0008]A machine oil regeneration system according to at least one embodiment of the present disclosure includes: a tank for storing in-use or used machine oil used for at least one of lubrication or power transmission; an adsorption system including: a column packed with an adsorbent; an oil circulation path for circulating the machine oil between the column and the tank; and an oil circulation pump disposed in the oil circulation path, the adsorption system being configured to perform adsorption treatment in which the machine oil is brought into contact with the adsorbent by driving the oil circulation pump; and an additive supply device configured to be able to add an additive for regeneration to the machine oil regardless of whether the adsorption treatment is being performed.

[0009]A method of adding a machine oil regeneration unit according to at least one embodiment of the present disclosure is a method of adding a machine oil regeneration unit for regenerating in-use or used machine oil used for at least one of lubrication or power transmission stored in a tank, including: a column installation step of installing a column packed with an adsorbent; an oil circulation path installation step of installing an oil circulation path for circulating the machine oil between the column and the tank; a pump installation step of installing an oil circulation pump on the oil circulation path; and an additive supply device installation step of installing an additive supply device configured to be able to add an additive for regeneration to the machine oil.

Advantageous Effects

[0010]The present disclosure provides a method of using machine oil, a machine oil regeneration system, and a method of adding a machine oil regeneration unit that enables continuous use of the machine oil without disposing of it.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is a schematic configuration diagram of a machine oil regeneration system according to an embodiment.

[0012]FIG. 2 is a flowchart showing a method of using machine oil according to an embodiment.

[0013]FIG. 3 is a graph schematically showing the relationship between RPVOT residual ratio and acid number for in-use or used machine oil.

[0014]FIG. 4 is a flowchart showing a method of using machine oil including additional steps according to an embodiment.

[0015]FIG. 5A is a schematic diagram showing details of a machine oil regeneration system according to the first embodiment.

[0016]FIG. 5B is a schematic diagram showing details of a machine oil regeneration system according to the second embodiment.

[0017]FIG. 5C is a schematic diagram showing details of a machine oil regeneration system according to the third embodiment.

[0018]FIG. 5D is a schematic diagram showing details of a machine oil regeneration system according to the fourth embodiment.

[0019]FIG. 5E is a schematic diagram showing details of a machine oil regeneration system according to the fifth embodiment.

[0020]FIG. 6A is a schematic diagram of a column according to the first embodiment.

[0021]FIG. 6B is a schematic diagram of a column according to the second embodiment.

[0022]FIG. 7 is a schematic diagram showing a machine oil regeneration system before modification according to an embodiment.

[0023]FIG. 8 is a flowchart showing a method of adding a machine oil regeneration unit according to an embodiment.

DETAILED DESCRIPTION

[0024]Embodiments of the present disclosure will be described below with reference to the accompanying drawings. It is intended, however, that unless particularly identified, dimensions, materials, shapes, relative positions, and the like of components described in the embodiments shall be interpreted as illustrative only and not intended to limit the scope of the present disclosure.

[0025]For instance, an expression of relative or absolute arrangement such as “in a direction”, “along a direction”, “parallel”, “orthogonal”, “centered”, “concentric” and “coaxial” shall not be construed as indicating only the arrangement in a strict literal sense, but also includes a state where the arrangement is relatively displaced by a tolerance, or by an angle or a distance whereby it is possible to achieve the same function.

[0026]For instance, an expression of an equal state such as “same” “equal” and “uniform” shall not be construed as indicating only the state in which the feature is strictly equal, but also includes a state in which there is a tolerance or a difference that can still achieve the same function.

[0027]Further, for instance, an expression of a shape such as a rectangular shape or a cylindrical shape shall not be construed as only the geometrically strict shape, but also includes a shape with unevenness or chamfered corners within the range in which the same effect can be achieved.

[0028]On the other hand, an expression such as “comprise”, “include”, “have”, “contain” and “constitute” are not intended to be exclusive of other components.

[0029]The same configurations are indicated by the same reference signs and may not be described again in detail.

<Overview of Machine Oil Regeneration System 1 >

[0030]FIG. 1 is a schematic configuration diagram of a machine oil regeneration system 1 according to an embodiment of the present disclosure. The machine oil regeneration system 1 is configured to regenerate machine oil 9 used by a machine oil-using device 100. The machine oil 9 is lubricating oil used to ensure the smooth operation of moving parts that make up the machine oil-using device 100, or hydraulic oil used in a hydraulic power transmission unit that makes up the machine oil-using device 100.

[0031]As an example, the machine oil-using device 100 may be a turbine, such as a steam turbine or gas turbine, and the lubricating oil may be turbine oil supplied to the turbine rotor or the like. As another example, the machine oil-using device 100 may be a hydraulic cylinder, and the hydraulic oil may be supplied to the interior of the hydraulic cylinder.

[0032]The lubricating oil and hydraulic oil are not limited to the above applications. The lubricating oil may also have other functions such as cooling the moving parts in addition to lubricating the moving parts. The hydraulic oil may also have other functions such as lubricating and cooling the power transmission parts in addition to the power transmission function.

[0033]The machine oil 9 degrades as it is used. For example, the longer the turbine oil is used, the more degraded components including organic acids such as carboxylic acids and altered substances of antioxidants become present in the turbine oil, causing the color to turn brown. In this case, the oil performance of the turbine oil, including the lubrication performance, deteriorates. The same degradation phenomenon is observed in the hydraulic oil. The machine oil regeneration system 1 is configured to regenerate the machine oil 9 in order to avoid disposing of used or in-use machine oil 9 due to degradation. The regeneration treatment includes at least one of the treatment of adding an additive 6 to the machine oil 9, or the adsorption treatment in which the machine oil 9 is brought into contact with an adsorbent 8 (see below for details).

[0034]The configuration of the machine oil regeneration system 1 will be described with reference to FIG. 1. The machine oil regeneration system 1 is provided with a tank 10 for storing machine oil 9 used in the machine oil-using device 100, an adsorption system 3 for performing the adsorption treatment in which the machine oil 9 is brought into contact with an adsorbent 8, and an additive supply device 50 for adding an additive 6 to the machine oil 9.

[0035]The tank 10 is designed so that the machine oil 9 flows into it from the machine oil-using device 100 via an oil discharge path 101. The machine oil 9 stored in the tank 10 is supplied to the machine oil-using device 100 via an oil supply path 102. In this example, the machine oil 9 is supplied from the tank 10 to the machine oil-using device 100 by operating a feed pump 105 disposed in the oil supply path 102. There may be one or multiple tanks 10 (in FIG. 1, a single tank 10 is illustrated). The tank 10 may be equipped with an mixer 130 for agitating the machine oil 9.

[0036]The adsorption system 3 includes a column 7 packed with an adsorbent 8, an oil circulation path 40 for circulating the machine oil 9 between the column 7 and the tank 10, and an oil circulation pump 48 disposed in the oil circulation path 40. The oil circulation path 40 has a supply path 41 for supplying the machine oil 9 from the tank 10 to the column 7, and a return path 42 for returning the machine oil 9 from the column 7 to the tank 10. The oil circulation pump 48 is disposed in the supply path 41. A filter 4 may be placed in the return path 42 to collect the adsorbent 8 that flows out of the column 7.

[0037]There may be one or multiple columns 7 (in FIG. 1, a single column 7 is illustrated). The adsorbent 8 packed in the column 7 may be silica gel, zeolite, activated alumina, activated clay, kaolin, or any combination thereof. Silica gel can be spherical silica gel or silica gel modified with amino groups.

[0038]The adsorption treatment performed by the adsorption system 3 is outlined below. The machine oil 9 stored in the tank 10 flows into the column 7 via the supply path 41 by the operation of the oil circulation pump 48. The machine oil 9 flowing in the column 7 comes into contact with the adsorbent 8 and is subjected to the adsorption treatment. More specifically, degraded components in the machine oil 9 are adsorbed onto the adsorbent 8, so that the degraded components are removed from the machine oil 9. The machine oil 9 discharged from the column 7 returns to the tank 10 via the return path 42. In this way, the degraded components are removed from the machine oil 9 in the tank 10, and the degradation level due to oxidation of the machine oil 9 can be reduced (see below for details on degradation level).

[0039]The additive supply device 50 is configured to add an additive 6 for regeneration to the machine oil 9. The additive supply device 50 may be configured to directly supply the additive 6 to the machine oil 9 in the tank 10 or may be configured to supply the additive 6 to the machine oil 9 flowing through the return path 42. The additive 6 may be an antioxidant, corrosion inhibitor, defoamer, anti-wear additive, extreme pressure additive, metal deactivator, demulsifier, or any combination thereof. Adding the additive 6 restores the oxidation stability of the machine oil 9 (see below for details on oxidation stability).

[0040]The additive supply device 50 is configured to add the additive 6 to the machine oil 9 regardless of whether the adsorption treatment is being performed. That is, the additive supply device 50 can add the additive 6 while the machine oil 9 is passing through the column 7 or while the machine oil 9 is not passing through the column 7.

[0041]The inventors have found that in order to continue to use the machine oil 9 while avoiding significant oil degradation, the machine oil 9 should be subjected to the adsorption treatment and the treatment of adding the additive 6 from time to time (details will be described below using FIG. 3). In this regard, with the above configuration, the adsorption system 3 can perform the adsorption treatment, and the additive supply device 50 can add the additive 6. This enables continuous use of the machine oil 9 without disposing of it. Furthermore, the inventors have found that the cycle in which the adsorption treatment becomes necessary as the degradation level due to oxidation increases can be extended than the cycle in which the addition of the additive 6 becomes necessary as the oxidation stability decreases. For example, if the machine oil 9 is turbine oil, the cycle in which the adsorption treatment becomes necessary can be adjusted to a value five to six times the cycle in which the addition of the additive 6 becomes necessary. In this regard, with the above configuration, the additive supply device 50 can perform the treatment of adding the additive 6 without performing the adsorption treatment by the adsorption system 3. This allows the adsorption treatment and the addition of the additive to be performed at individually appropriate timings and realizes the machine oil regeneration system 1 that avoids unnecessary regeneration treatment of the machine oil 9.

<Overview of Method of Using Machine Oil 9 >

[0042]Referring to FIG. 2, the method for continuing to use the machine oil 9 with the machine oil regeneration system 1 is outlined. FIG. 2 is a flowchart showing a method of using machine oil 9 according to an embodiment of the present disclosure. In the illustrated example, the regeneration treatment of the machine oil 9 is performed only by the addition of the additive 6, without the adsorption treatment by the adsorption system 3. In the following description, “step” may be abbreviated as “S”.

[0043]First, the first oxidation stability determination step (S11) is performed to determine whether the oxidation stability of the in-use or used machine oil 9 is equal to or higher than a first specified level. For example, an operator may collect the machine oil 9 from the tank 10 to evaluate the oxidation stability of the machine oil 9 at regular intervals. More specifically, the oxidation stability of the machine oil 9 is evaluated by the RPVOT residual ratio of the machine oil 9. The RPVOT residual ratio is the ratio of the RPVOT value of the machine oil 9 in used condition to the RPVOT value of the machine oil 9 in unused condition. RPVOT values are measured by the operator through the use of various measuring instruments in accordance with “Rotating Pressure Vessel Oxidation Stability” in JIS K 2514-3. The RPVOT residual ratio is between 0% to 100%. As the degradation level due to oxidation of the machine oil 9 increases, the RPVOT residual ratio decreases. In S11, the oxidation stability is determined to be equal to or higher than the first specified level when the RPVOT residual ratio is equal to or higher than a first threshold. The first threshold is determined based on the relationship as shown in FIG. 3. For oil types such as those illustrated, where the acid number increases rapidly when the RPVOT residual ratio falls below 50%, the first threshold is not less than 50%, more specifically not less than 70%. Thus, the first threshold is set appropriately according to the relationship between the RPVOT residual ratio and the acid number.

[0044]If it is determined that the oxidation stability is equal to or higher than the first specified level (S11: YES), the first continuous use step (S13) is executed to continue to use the in-use or used machine oil 9. More specifically, if the feed pump 105 is stopped before the start of this flowchart, the feed pump 105 may resume operation upon a positive determination in S11. Alternatively, if the feed pump 105 continues to operate after the start of this flowchart, a command indicating further continued operation may be input to the feed pump 105 upon a positive determination in S11. After S13, the process returns to S11.

[0045]When the machine oil 9 is used continuously, it is eventually determined that the oxidation stability is lower the first specified level (S11: NO). In this case, the addition step is executed to add the additive 6 to the machine oil 9 so that the oxidation stability is equal to or higher than a second specified level (S51). According to a command entered by the operator or controller, the machine oil-using device 100 adds the additive 6 to the machine oil 9. As a result, the oxidation stability is restored.

[0046]After S51, it is determined whether the oxidation stability of the machine oil 9 is equal to or higher than the second specified level (S53). More specifically, it is determined whether the RPVOT residual ratio is equal to or higher than a second threshold. The second threshold can be any value that is equal to or higher than the first threshold, and in this example, it is higher than the first threshold. In other words, the second specified level in this example is higher than the first specified level. If it is determined that the oxidation stability is lower than the second specified level (S53: NO), the process returns to S51. If it is determined that the oxidation stability is equal to or higher than the second specified level (S53: YES), the second continuous use step (S55) is executed to continue to use the machine oil 9 to which the additive 6 has been added. S55 is the same step as S13, after which the process returns to S11.

[0047]Here, in S51, new additive 6 is successively fed, so the oxidation stability almost certainly returns to the second specified level or higher through repetition of S51 and S53. Therefore, with the above using method, the machine oil 9 can continue to be used for a long period of time. For example, it is possible to continue to use the machine oil 9 for several years or more.

[0048]The evaluation of the oxidation stability performed in S11 and S53 may be based on parameters other than the RPVOT residual ratio, such as kinematic viscosity of the machine oil 9. The present disclosure is not limited to directly measuring the RPVOT residual ratio, but the oxidation stability may be evaluated by sensing parameters that correlate with the RPVOT residual ratio. In this case, S11 and S53 may be executed by a controller instead of the operator.

[0049]The inventors have found that if the additive 6 is added to the machine oil 9 from time to time so that the oxidation stability of the machine oil 9 is maintained above a certain level, the machine oil 9 can continue to be used while maintaining the oil performance. Specifically, they have obtained the findings shown in FIG. 3. This figure is a graph showing the relationship between RPVOT residual ratio and acid number, which the inventors have obtained by testing used machine oil 9 (more specifically, turbine oil). As can be seen from the graph, the acid number of the machine oil 9, which is an indicator of the degradation level due to oxidation, increases rapidly when the RPVOT residual ratio of the machine oil 9 falls below 50%. In other words, they have found that by repeating the treatment of adding the additive 6 so that the RPVOT residual ratio of the machine oil 9 does not fall below 50%, the machine oil 9 can continue to be used while controlling the degradation level of the machine oil 9.

[0050]In this regard, with the method of using the machine oil 9 as illustrated in FIG. 2, even if the oxidation stability of the machine oil 9 falls below the first specified level, the oxidation stability of the machine oil 9 can be restored to the second specified level or higher by executing the step (S51) of adding the additive 6. Thus, the degradation level due to oxidation of the machine oil 9 can be maintained at the initial level, and the machine oil 9 can continue to be used without disposal.

<Method of Using Machine Oil 9 with Additional Steps>

[0051]FIG. 4 is a flowchart showing a method of using machine oil 9 including additional steps according to an embodiment of the present disclosure. In FIG. 4, the same step numbers are assigned to the same steps as in FIG. 2, and their descriptions are omitted or simplified below. In FIG. 4, in addition to the steps shown in FIGS. 2, S21 to S29 are executed, which are related to the adsorption treatment.

[0052]S21 is executed if a negative determination is made in S11. In S21, it is determined whether the degradation level due to oxidation of the in-use or used machine oil 9 is lower than a first progression level. The degradation level due to oxidation is, for example, the acid number. If the acid number is lower than a first acid number threshold, the degradation level is determined to be lower than the first progression level. Conversely, if the acid number is equal to or higher than the first acid number threshold, the degradation level is determined to be equal to or higher the first progression level. The first acid number threshold is, for example, 0.1 [mgKOH/g]. Acid numbers are measured by the operator through the use of various measuring instruments in accordance with JIS K 2501:2003.

[0053]If it is determined that the degradation level is equal to or higher than the first progression level (S21: NO), the adsorption step (S23) is executed to apply adsorption treatment to the machine oil 9. More specifically, the oil circulation pump 48 is activated, causing the machine oil 9 to flow into the column 7 to perform the adsorption treatment.

[0054]After S23, it is determined whether the degradation level of the machine oil 9 is lower than a second progression level (S25). More specifically, it is determined whether the acid number is lower than a second acid number threshold. The second acid number threshold can be any value that is equal to or lower than the first acid number threshold, and in this example, it is equal to the first acid number threshold. If it is determined that the degradation level is lower than the second progression level (S25: YES), the above-described step (S51) is executed to add the additive 6 to the machine oil 9.

[0055]If the degradation level is equal to or higher than the second progression level (S25: NO), it is determined whether the number of consecutive executions (N) of the adsorption treatment is equal to or more than a specified number of times. If N is less than the specified number of times (S27: NO), S23 and S25 are again executed in sequence. N is the number of consecutive executions of S23 as well as the number of consecutive executions of S25.

[0056]According to the inventors' knowledge, if the adsorbent 8 is used continuously over a long period of time, the adsorption capacity of the adsorbent 8 decreases as degraded components accumulate in the adsorbent 8. In this case, even if the adsorption treatment (S23) is performed repeatedly, the degradation level does not fall below the second progression level (S25: NO) and N reaches the specified number of times (S27: YES). In this case, the column 7 packed with the adsorbent 8 is replaced with a new column 7 (S29). Thereafter, the process returns to S23. After the replacement of the column 7, sufficient adsorption capacity is demonstrated in S23, the degradation level falls below the second progression level (S25: YES), and the above-described S51 is executed. N is initialized to 0 when S29 is executed.

[0057]The present disclosure is not limited to evaluating the degradation level in S21 and S25 based on the acid number. For example, the degradation level may be evaluated by sensing parameters that correlate with the acid number. In this case, S21 and S25 may be executed by a controller instead of the operator.

[0058]In the example of FIG. 4, if it is determined that the degradation level of the machine oil 9 is lower than the first progression level (S21: YES), the step (S51) is executed to add the additive 6. According to the inventors' knowledge, even when the additive 6 is added and the machine oil 9 is continuously used, the degradation level of the machine oil 9 due to oxidation increases. In this regard, with the above configuration, since the addition step (S51) is executed for the machine oil 9 with suppressed degradation level, it is possible to avoid the problem where the degradation level due to oxidation is not restored even after the addition step is executed.

[0059]In the example of FIG. 4, the step (S51) of adding the additive 6 is also executed when the degradation level has fallen below the second progression level (S25: YES) by performing the adsorption treatment (S23). If the degradation level of the machine oil 9 is high, the adsorption treatment (S23) is performed prior to the addition step (S51), which ensures that the degradation level of the machine oil 9 due to oxidation is maintained at the initial level.

[0060]In the example of FIG. 4, if the degradation level does not fall below the second progression level even after the adsorption treatment (S23) is repeated (S25: NO, S27: YES), the column 7 packed with the adsorbent 8 is replaced (S29). By replacing the adsorbent 8 when the adsorption capacity is reduced due to continuous use of the adsorbent 8, effective adsorption treatment can be maintained on an ongoing basis. Thus, the machine oil 9 can continue to be used for a longer period of time.

Example of Specific Configuration of Machine Oil Regeneration System 1

[0061]A specific configuration of the machine oil regeneration system 1 according to some embodiments will be described with reference to FIGS. 5A to 5E. FIG. 5A shows a schematic representation of a machine oil regeneration system 1A (1) according to the first embodiment, FIG. 5B shows a machine oil regeneration system 1B (1) according to the second embodiment, FIG. 5C shows a machine oil regeneration system 1C (1) according to the third embodiment, FIG. 5D shows a machine oil regeneration system 1D (1) according to the fourth embodiment, and FIG. 5E shows a machine oil regeneration system 1E (1) according to the fifth embodiment.

[0062]As shown in FIGS. 5A to 5D, the machine oil regeneration system 1A to 1D (1) is equipped with a tank 10A to 10D (10), an additive supply device 50A to 50D (50), and an oil circulation path 40A to 40D (40).

[0063]The additive supply device 50A to 50D (50) is configured to supply the additive 6 into the tank 10A to 10D (10) via an additive supply path 55 that is different from the oil circulation path 40A to 40D (40). The additive supply path 55 may be a pipe connected to the tank 10A to 10D or may be a space (area) through which the additive 6 passes as it falls. The additive 6 flows into the tank 10A to 10D at a position away from both the connection point C1 between the supply path 41 and the tank 10A to 10D and the connection point C2 between the return path 42 and the tank 10A to 10D.

[0064]The treatment of adding the additive 6 is performed at a separate position from the oil circulation path 40 where the adsorption treatment is performed. This makes it easier to perform the treatment of adding the additive 6 separately from the adsorption treatment.

[0065]As shown in FIGS. 5A to 5C, the tank 10A to 10C includes a first tank 11 and a second tank 12. The first tank 11 is connected to each of the oil discharge path 101 and the oil supply path 102. That is, the first tank 11 is configured to store the machine oil 9 discharged from the machine oil-using device 100 and to release the machine oil 9 toward the machine oil-using device 100.

[0066]The second tank 12 is disposed separately from the first tank 11. The second tank 12 is connected to the oil circulation path 40. That is, the machine oil 9 stored in the second tank 12 is supplied to the column 7 via the supply path 41, and the machine oil 9 flowing out of the column 7 returns to the column 7 via the return path 42.

[0067]The machine oil regeneration system 1A to 1C includes a connection path unit 60 connecting the first tank 11 and the second tank 12. The connection path unit 60 includes a first oil path 61 for guiding the machine oil 9 from the first tank 11 to the second tank 12, a first pump 63 disposed in the first oil path 61, a second oil path 62 for guiding the machine oil 9 from the second tank 12 to the first tank 11, and a second pump 64 disposed in the second oil path 62. When performing the regeneration treatment of the machine oil 9, the first pump 63 is driven, and the machine oil 9 flows from the first tank 11 to the second tank 12. The regenerated machine oil 9 in the second tank 12 is returned to the first tank 11 by driving the second pump 64.

[0068]The additive supply device 50A to 50C is configured to supply the additive 6 to at least the second tank 12. More specifically, the additive supply device 50A to 50C includes a second additive supply device 52 for supplying the additive 6 to the second tank 12. Further, the mixer 130A to 130C (130) includes a second mixer 132 for agitating the machine oil 9 stored in the second tank 12.

[0069]With the above configuration, the regeneration treatment of the machine oil 9 is performed in the second tank 12, which is different from the first tank 11 where the machine oil 9 is required to be released as needed toward the machine oil-using device 100. This makes the regeneration treatment easier to perform. As a more specific example, in an embodiment where the machine oil 9 is regenerated in a batch manner during the regular inspection of the machine oil-using device 100, the machine oil 9 can be regenerated in the second tank 12, which is different from the first tank 11. As another example, in an embodiment where the machine oil 9 is regenerated in a continuous manner during operation of the machine oil-using device 100, the machine oil 9 can be regenerated in the second tank 12, which is different from the first tank 11, so that the machine oil 9 can be regenerated without impeding the flow of the machine oil 9 between the first tank 11 and the machine oil 9.

[0070]As shown in FIGS. 5B and 5C, the additive supply device 50B, 50C further includes a first additive supply device 51 for supplying the additive 6 to the first tank 11 in addition to the second additive supply device 52. The mixer 130B, 130C (130) includes a first mixer 131 for agitating the machine oil 9 stored in the first tank 11. With the above configuration, since the treatment of adding the additive 6 can be performed in both the first tank 11 and the second tank 12, the oil performance can be maintained more reliably.

[0071]As shown in FIG. 5C, the second tank 12 of the tank 10C is connected to the first tank 11 through the connection path unit 60 while the second tank 12 is mounted on a transport vehicle 5. The connection path unit 60 is placed detachably to the first tank 11 and the second tank 12. The adsorption system 3 may be mounted on the transport vehicle 5 together with the second tank 12 or may be connected to the second tank 12 while installed on land. With the above configuration, only when the regeneration treatment of the machine

[0072]oil 9 is necessary, the transport vehicle 5 equipped with the second tank 12 may be moved to the vicinity of the first tank 11, and the second tank 12 may be connected to the first tank 11 through the connection path unit 60. This allows the second tank 12 and the connection path unit 60 to be used in another machine oil regeneration system 1 or stored in a dedicated area when the regeneration treatment is not necessary. Thus, it is possible to make use of the second tank 12 and the connection path unit 60 more flexibly.

[0073]As shown in FIG. 5D, the tank 10D of the machine oil regeneration system 1D includes a first tank 11 and does not include a second tank 12 (see FIGS. 5A to 5C). In the example shown in FIG. 5D, the oil circulation path 40D is connected to the first tank 11, and the additive supply device 50D includes a first additive supply device 51 and does not include a second additive supply device 52 (see FIGS. 5A to 5C). With the above configuration, since the regeneration treatment of the machine oil 9 can be performed without installing the second tank 12 separate from the first tank 11, the machine oil regeneration system 1 can be made more compact.

[0074]As shown in FIG. 5E, the tank 10E (10) of the machine oil regeneration system 1E (1) includes a first tank 11 and does not include a second tank 12 (see FIGS. 5A to 5C). Furthermore, the oil circulation path 40E (40) constituting the machine oil regeneration system 1E (1) further has a bypass path 43 connected to the supply path 41 and the return path 42 so as to bypass the column 7.

[0075]The oil circulation path 40E is further equipped with a valve 45. The valve 45 is configured to allow the machine oil 9 flowing through the supply path 41 to selectively flow into either the column 7 or the bypass path 43. The valve 45 in this example is a three-way valve disposed at the connection between the bypass path 43 and the supply path 41. The valve 45 may be an open/close valve disposed in at least one of the bypass path 43 or the supply path 41.

[0076]The oil circulation pump 48 illustrated in FIG. 5E is disposed in the supply path 41 at a position upstream of the valve 45. The present disclosure is not limited thereto, and the oil circulation pump 48 may include a first oil circulation pump disposed between the valve 45 and the column 7, and a second oil circulation pump disposed in the bypass path 43.

[0077]The additive supply device 50E illustrated in FIG. 5E is disposed in the return path 42 at a position of where the bypass path 43 is connected to the return path 42. When the treatment of adding the additive 6 is performed, the valve 45 switches to prevent the machine oil 9 flowing into the bypass path 43. The additive 6 is added from the additive supply device 50E to the machine oil 9 flowing through the return path 42 via the bypass path 43 by driving the oil circulation pump 48. When the adsorption treatment in the column 7 is performed, the valve 45 switches to allow the machine oil 9 to flow into the column 7. As a result, the machine oil 9 flowing through the supply path 41 flows through the supply path 41, the column 7, and the return path 42 in that order as the oil circulation pump 48 is driven. At this time, the additive supply device 50E does not operate.

[0078]With the above configuration, the treatment of adding the additive 6 or the adsorption treatment can be selectively performed on the machine oil 9 flowing through the oil circulation path 40.

Example of Specific Configuration of Column 7

[0079]FIG. 6A is a schematic diagram of a column 7A (7) according to the first embodiment. FIG. 6B is a schematic diagram of a column 7B (7) according to the second embodiment. The columns 7A, 7B may be applied to any of the machine oil regeneration systems 1A to 1E (1) shown in FIGS. 5A to 5E.

[0080]As shown in FIG. 6A, in the first embodiment, a plurality of columns 7A (7) are arranged in parallel with each other on the oil circulation path 40F (40). More specifically, the oil circulation path 40F has a plurality of column connecting paths 47 on which the plurality of columns 7A are arranged, respectively. Each of the plurality of column connecting paths 47, which are arranged in parallel with each other, is connected to the supply path 41 and the return path 42. A plurality of flow control valves 46 may be arranged on the plurality of column connecting paths 47, respectively. In addition, a plurality of open/close valves 44 may be further arranged on the plurality of column connecting paths 47, respectively.

[0081]With the configuration in which the plurality of columns 7A are arranged in parallel with each other, the flow reduction due to pressure drop of the machine oil 9 in the oil circulation path 40F can be suppressed, so that the required time for the adsorption treatment can be reduced. With the configuration in which the plurality of flow control valves 95 are arranged on the plurality of column connecting paths 47, respectively, the machine oil 9 can be distributed evenly into the plurality of columns 7A, so that the adsorption treatment can be executed evenly in the plurality of columns 7A.

[0082]At least one of the plurality of columns 7A shown in FIG. 6A is configured to be replaceable with a new column 7A packed with new adsorbent 8. For example, the open/close valve 44 corresponding to the column 7A that has reached its replacement time among the plurality of columns 7A may be closed to replace the column 7A with a new column 7A. During the replacement, the machine oil 9 may be introduced into the remaining columns 7A that are not due for replacement to perform the adsorption treatment. With the above configuration, the adsorption capacity can be restored by replacing the column 7A, allowing the machine oil 9 to continue to be used for a longer period of time.

[0083]As shown in FIG. 6A, a heater 77 may be further disposed in the oil circulation path 40F to adjust the temperature of the machine oil 9 flowing in the column 7A. In the illustrated example, the heater 77 is disposed upstream of the connection point between the supply path 41 and the plurality of column connecting paths 47. With the above configuration, the temperature of the machine oil 9 can be made suitable for the adsorption treatment to improve the adsorption efficiency in the column 7A.

[0084]As shown in FIG. 6B, the column 7B (7) includes one end portion 71 where the inlet 7a for the machine oil 9 is formed, and the other end portion 72 where the outlet 7b for the machine oil 9 is formed. In the flow direction of the machine oil 9 in the column 7B (direction of arrow Z), one end portion 71 has a shape in which the inner diameter decreases toward the upstream side, and the other end portion 72 has a shape in which the inner diameter decreases toward the downstream side. With the above configuration, the machine oil 9 is prevented from stagnating in the vicinity of the inlet 7a or the outlet 7b, enabling more effective adsorption treatment of the machine oil 9.

<Machine Oil Regeneration Unit 2 >

[0085]Referring to FIGS. 7 and 8, an example is given as to how to add a machine oil regeneration unit 2, including the adsorption system 3 and the additive supply device 50, to a machine oil regeneration system 1F (1) before modification. FIG. 7 is a schematic diagram showing a machine oil regeneration system 1F before modification according to an embodiment of the present disclosure. FIG. 8 is a flowchart showing a method of adding a machine oil regeneration unit 2 according to an embodiment of the present disclosure. The machine oil regeneration unit 2 (see FIG. 1) is a unit including the adsorption system 3 and the additive supply device 50.

[0086]As illustrated in FIG. 7, the machine oil regeneration system 1F before modification includes the tank 10 but does not include the machine oil regeneration unit 2 (see FIG. 1). As shown in FIG. 8, in the method of adding the machine oil regeneration unit 2, the column installation step (S101) is first executed to install the column 7 filled with the adsorbent 8. Then, the oil circulation path installation step (S103) is executed to install the oil circulation path 40. In S103, at least the supply path 41 and the return path 42 are installed. In S103, the bypass path 43 may be further installed. In this case, the valve 45 is also installed together.

[0087]Then, the pump installation step (S105) to install the oil circulation pump 48 on the oil circulation path 40, the additive supply device installation step (S107) to install the additive supply device 50, and the mixer installation step (S109) to install the mixer 130 in the tank 10 are executed in sequence. This completes the machine oil regeneration system 1, with the machine oil regeneration unit 2 installed (see FIG. 1).

[0088]S101 to S109 are executed by the operator, a robot arm operated by the operator, or a combination thereof. The order of execution of S101 to S109 may be changed as appropriate. In addition to the steps shown in FIG. 8, an additional step may be executed to install the heater 77 on the supply path 41. Furthermore, if the tank 10 before modification has only the first tank 11, the method of adding the machine oil regeneration unit 2 may further include the step of adding the second tank 12 and the step of adding the connection path unit 60.

<Others>

[0089]The “controller” described above comprises a computer, and includes a processor, a memory (storage medium), and an external communication interface. The processor is, for example, CPU, GPU, MPU, DSP, or a combination of these. The memory is configured to temporarily or non-temporarily store various data, and is implemented by at least one of RAM, ROM, or a flash memory, for example. The processor executes various control processes in accordance with programs loaded in the memory.

<Conclusion>

[0124]With the above configuration 17), the same technical advantages as in the above 5) are achieved.

REFERENCE SIGNS LIST