阅读说明：本技术 油的淤渣生成性判定方法 (Method for determining sludge formation in oil ) 是由 矢野昭彦 野崎昭宏 于 2019-09-19 设计创作，主要内容包括：本发明的油的淤渣生成性判定方法具备劣化油生成步骤(ST1)、RPVOT试验步骤(ST2A)、淤渣量测定步骤(ST2B)及判定步骤(ST3)。在劣化油生成步骤(ST1)中,将加入油及铜催化剂并利用氧进行置换或注入氧或者空气而加压至氧分压成为比大气压下的值更高的规定压力的加压容器浸渍于规定温度的恒温槽中并使其旋转,从而生成油氧化而成的劣化油。在RPVOT试验步骤(ST2A)中,对所生成的劣化油的一部分,通过RPVOT试验测定RPVOT残留率。在淤渣量测定步骤(ST2B)中,对所生成的劣化油的一部分测定淤渣量。在判定步骤(ST3)中,根据所测定的RPVOT残留率与淤渣量之间的关系判定油的劣化引起的淤渣的易生成性。(The method for determining sludge formation in oil according to the present invention comprises a deteriorated oil formation step (ST1), an RPVOT test step (ST2A), a sludge amount measurement step (ST2B), and a determination step (ST 3). In the degraded oil producing step (ST1), a pressurized vessel, in which oil and a copper catalyst are added, oxygen is substituted by oxygen or air is injected, and pressurized to a predetermined pressure at which the oxygen partial pressure becomes a value higher than that at atmospheric pressure, is immersed in a constant temperature bath at a predetermined temperature and rotated, thereby producing a degraded oil in which the oil is oxidized. In the RPVOT test step (ST2A), the RPVOT residual rate is measured by the RPVOT test on a part of the produced deteriorated oil. In the sludge amount measuring step (ST2B), the amount of sludge is measured for a part of the produced deteriorated oil. In the determination step (ST3), the ease of generation of sludge due to degradation of the oil is determined from the relationship between the measured RPVOT residual rate and the amount of sludge.)

1. A method for determining sludge formation in oil, comprising the steps of:

immersing a pressurizing vessel, into which an oil and a copper catalyst are added, and which is pressurized by replacing oxygen with oxygen or injecting oxygen or air until the oxygen partial pressure becomes a predetermined pressure higher than the value under atmospheric pressure, in a thermostatic bath at a predetermined temperature and rotating the vessel, thereby producing a deteriorated oil in which the oil is oxidized;

measuring an RPVOT residual rate, which is an index value indicating a degree of deterioration of the deteriorated oil due to oxidation, and measuring a weight of sludge, which is a filtration residue, by an RPVOT test with respect to a part of the produced deteriorated oil; and

determining the sludge-susceptibility to generation caused by the oil deterioration based on the relationship between the measured RPVOT residual rate and the weight of the sludge.

2. The method for determining the sludge formation of oil according to claim 1,

the predetermined pressure is 0.3(MPa) or more and 1.0(MPa) or less.

3. The method of determining sludge formation of oil according to claim 1 or 2,

the prescribed temperature is 130 (DEG C) or more and 150 (DEG C) or less.

4. The method for determining sludge formation of oil according to any one of claims 1 to 3,

determining a 1 st period during which the estimated value of the RPVOT residual rate becomes approximately 0 (%) when the pressure in the pressurized container is decreased from the maximum pressure to a predetermined pressure,

the step of generating the deteriorated oil is performed in a 2 nd period shorter than the 1 st period,

and in the period 2, adjusting according to the RPVOT residual rate value of the degraded oil to be generated.

5. The method for determining sludge formation of oil according to any one of claims 1 to 4,

in the step of generating the deteriorated oil, the deteriorated oil is generated using a test apparatus used in the RPVOT test.

6. The method for determining sludge formation of oil according to any one of claims 1 to 5,

the RPVOT test is the test specified in ASTM D2272.

Technical Field

The present invention relates to a method for determining sludge formation in oil.

Background

Conventionally, there is known a technique for determining the performance of oils used for various purposes in order to increase the service life. For example, a large amount of lubricating oil is used for lubricating turbine bearings, and a part of the units is periodically replaced and operated, and therefore, a long life is required. One of the indexes for achieving a longer oil life is the tendency of sludge to be easily generated due to degradation caused by oxidation. If sludge is generated during the deterioration, for example, the sludge is deposited on the bearing surface, or the bearing temperature is increased. As a result, tripping and inspection of the turbine may be required. Therefore, it becomes important to grasp the tendency of the amount of sludge generated in the process of deterioration of the oil.

Patent document 1 describes a determination method for determining the sludge-formation-susceptibility of a lubricating oil from the RBOT-residue rate by performing an oxidation degradation test of the lubricating oil to produce a degraded oil, determining the RBOT-residue rate as a degradation index by an RBOT test (a rotary gas cylinder oxidation stability test, an RPVOT test) on the produced degraded oil, and determining the weight of sludge (filter residue).

Prior art documents

Patent document

Patent document 1: japanese patent No. 4209093

Disclosure of Invention

Technical problem to be solved by the invention

In the determination method described in patent document 1, a TOST test (turbine oil oxidation stability test) is applied as an oxidation degradation test for producing a degraded oil. The TOST test is a test in which water, a lubricant, a catalyst of copper and iron, and oxygen under atmospheric pressure are blown into a test tube while the test tube is immersed in a thermostatic bath at 95 ℃. In the oxidation degradation test described in patent document 1, a Dry TOST test is used in which oxidation of the lubricating oil is accelerated by setting the temperature of the thermostatic bath to 120 ℃ without adding water. However, in the Dry TOST test, in order to sufficiently degrade the lubricating oil, a time of about 500 hours to about 3000 hours is sometimes required, and there is a problem that a test for determining the easiness of generation of sludge cannot be rapidly performed.

The present invention has been made in view of the above circumstances, and an object thereof is to more quickly determine the ease of generation of sludge due to degradation of oil.

Means for solving the technical problem

In order to solve the above problems and achieve the object, the present invention includes: immersing a pressurizing vessel, into which an oil and a copper catalyst are added, and which is pressurized by replacing oxygen with oxygen or injecting oxygen or air until the oxygen partial pressure becomes a predetermined pressure higher than the value under atmospheric pressure, in a thermostatic bath at a predetermined temperature and rotating the vessel, thereby producing a deteriorated oil in which the oil is oxidized; measuring an RPVOT residual rate, which is an index value indicating a degree of deterioration of the deteriorated oil due to oxidation, and measuring a weight of sludge, which is a filtration residue, by an RPVOT test with respect to a part of the produced deteriorated oil; and determining the sludge-susceptibility to generation caused by the oil deterioration based on the relationship between the measured RPVOT residual rate and the weight of the sludge.

With this structure, in the step of producing the deteriorated oil, oxygen or air is replaced or injected with oxygen, whereby the oil is oxidized at a predetermined pressure at which the partial pressure of oxygen is higher than the value at atmospheric pressure, and therefore the deteriorated oil can be obtained quickly. Then, the RPVOT residual rate of a part of the produced deteriorated oil is measured in the RPVOT test step, and the amount of the filtration residue, i.e., sludge is measured. This makes it possible to measure the RPVOT residual rate and the amount of sludge of the deteriorated oil in parallel. As a result, the obtained RPVOT residual rate and the amount of sludge are correlated with each other, and the sludge-susceptibility to generation due to oil degradation can be determined more quickly.

The predetermined pressure is preferably 0.3(MPa) or more and 1.0(MPa) or less.

With this structure, the deteriorated oil can be obtained quickly in the step of producing the deteriorated oil.

The predetermined temperature is preferably 130 (DEG C) or more and 150 (DEG C) or less.

With this structure, the deteriorated oil can be obtained quickly in the step of producing the deteriorated oil.

Preferably, the step of generating the deteriorated oil is performed in a 1 st period in which an estimated value of the RPVOT residual rate is determined to be substantially 0 (%) by decreasing the pressure in the pressurized vessel from a maximum pressure to a predetermined pressure, and the 2 nd period is adjusted according to a value of the RPVOT residual rate of the deteriorated oil to be generated, and is performed in a 2 nd period shorter than the 1 st period.

With this configuration, in the step of generating the degraded oil, the degraded oil close to the desired RPVOT residual rate can be accurately generated only by adjusting the 2 nd period.

Preferably, in the step of generating the deteriorated oil, the deteriorated oil is generated using a test apparatus used in the RPVOT test.

With this configuration, both the step of generating the deteriorated oil and the step of performing the RPVOT test can be performed if there is a test apparatus used in the RPVOT test, and therefore, it is not necessary to prepare a plurality of types of test apparatuses, and cost reduction can be achieved.

Also, preferably, the RPVOT test is the test specified in ASTM D2272.

Drawings

Fig. 1 is a flowchart illustrating an example of a method for determining sludge formation in oil according to an embodiment.

Fig. 2 is a schematic diagram showing an RPVOT test apparatus used in the RPVOT test.

Fig. 3 is an explanatory diagram showing test conditions in the method for determining sludge formation in oil according to the embodiment.

Fig. 4 is an explanatory diagram showing an example of a change in pressure in the pressurized container according to the execution time of the degraded oil producing step.

Fig. 5 is an explanatory diagram showing an example of the relationship between the estimated RPVOT residual rate and the actual RPVOT residual rate.

Fig. 6 is an explanatory diagram showing an example of the relationship between the RPVOT residual rate measured in the RPVOT test step and the amount of sludge measured in the sludge amount measurement step.

Fig. 7 is an explanatory diagram showing an example of the execution time required until the degraded oil having a different RPVOT residual rate is generated in the degraded oil generation step.

Detailed Description

Hereinafter, an embodiment of the method for determining sludge formation in oil according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment.

Fig. 1 is a flowchart illustrating an example of a method for determining sludge formation in oil according to an embodiment. The method for determining sludge formation in oil according to the embodiment is used, for example, for determining sludge formation in lubricating oil used for lubricating a bearing of a turbine or the like by grasping a tendency of the weight of sludge (the weight of filtered residue) generated during deterioration and determining the degree of deterioration. The method for determining sludge formation in oil according to the embodiment may be performed on oil other than lubricating oil used for lubricating bearings of turbines.

As shown in fig. 1, the method for determining sludge formation in oil according to the embodiment includes a degraded oil formation step ST1, an RPVOT (rotary Pressure Vessel Oxidation Test) Test step ST2A, a sludge amount measurement step ST2B, and a determination step ST 3. The respective processes shown in fig. 1 are performed by workers using various devices.

The worker first performs the degraded oil producing step ST 1. The deteriorated oil generation step ST1 is a step of immersing a pressurizing vessel, which is charged with oil and a copper catalyst and pressurized to a predetermined pressure Pref (refer to fig. 3) in which the partial pressure of oxygen is higher than the value under the atmospheric pressure by replacing oxygen with oxygen or injecting oxygen or air, in a thermostatic bath at a predetermined temperature and rotating the pressurizing vessel, thereby generating a deteriorated oil in which the oil is oxidized. The deteriorated oil production step ST1 was performed by a worker using a test apparatus used in a rotary gas cylinder oxidation stability test (hereinafter, referred to as an "RPVOT test") which is one of oil oxidation deterioration tests.

Fig. 2 is a schematic diagram showing an RPVOT test apparatus used in the RPVOT test. As shown in the figure, the RPVOT test apparatus 10 includes a pressure vessel 11, a copper catalyst 12, and a constant temperature bath 13. The pressurizing vessel 11 is a gas cylinder (pressure-resistant vessel) capable of pressurizing the partial pressure of oxygen to a predetermined pressure Pref by replacing oxygen or injecting oxygen or air. In the degraded oil producing step ST1, the lubricant oil 1 as a sample and the copper catalyst 12 for promoting oxidation of the lubricant oil 1 are disposed inside the pressurized container 11. The pressurized container 11 can be rotated in the thermostatic bath 13 by power from a drive source (e.g., a motor), not shown. The pressure in the pressurized container 11 is detected by a pressure measuring instrument, not shown. The copper catalyst 12 is a copper catalyst, and is formed in a coil shape in the present embodiment. The constant temperature bath 13 is maintained at a predetermined temperature, and the pressurized container 11 is immersed therein.

In the degraded oil producing step ST1, the lubricating oil 1 and the copper catalyst 12 are charged into the pressurizing vessel 11. Next, oxygen is injected to set the oxygen partial pressure in the pressurized container 11 to a predetermined pressure Pref higher than the value under atmospheric pressure, the pressurized container 11 is immersed in a constant temperature bath 13 set to a predetermined temperature Tref (see fig. 3), and the pressurized container 11 is rotated in the constant temperature bath 13 by power from a drive source (not shown). The deteriorated oil producing step ST1 is performed within the execution time t (see fig. 4) with the time when the pressurized container 11 is immersed in the thermostatic bath 13 as the start time. This generates a deteriorated oil obtained by oxidizing the lubricating oil 1 in the pressurized container 11.

In the present embodiment, the same type of lubricating oil 1 is subjected to the multiple degraded oil producing step ST1 with the execution time t changed, thereby producing multiple degraded oils with different RPVOT residual ratios, which will be described later. Here, the RPVOT residual rate is an index value indicating the degree of degradation of the degraded oil due to oxidation, and an actual measurement value is measured in an RPVOT test step ST2A, which is a subsequent step. The RPVOT residual ratio is 100% in the fresh oil, and the larger the degree of progress of degradation due to oxidation, the smaller the value. In the present embodiment, the deteriorated oil producing step ST1 of 2 sets is performed at the same performing time t, thereby producing the deteriorated oil of 2 sets having the same RPVOT residual ratio.

The conditions for carrying out the degraded oil producing step ST1 will be described with reference to fig. 3. Fig. 3 is an explanatory diagram showing test conditions in the method for determining sludge formation in oil according to the embodiment. The central column in fig. 3 shows the test conditions of the degraded oil producing step ST 1. In fig. 3, for comparison, the test conditions of the Dry TOST test defined in ASTM D7873 are attached to the left column. The Dry TOST test is a test method in which a lubricating oil is oxidized by introducing 360ml of the lubricating oil, a copper catalyst and an iron catalyst (each having a diameter of 1.6mm (middle) and a length of 3 m) into a test tube without adding water, and blowing oxygen under atmospheric pressure at 3L/min while immersing the test tube in a 120 ℃ thermostatic bath. In this Dry TOST test, depending on the type of the lubricant oil 1, an execution time of about 500 hours to about 3000 hours may be required in order to generate a degraded oil having a sufficiently reduced RPVOT residual rate.

As shown in fig. 3, in the degraded oil producing step ST1 according to the embodiment, the oil amount of the lubricating oil 1 per group 1 is set to 60 (g). In the present embodiment, since the group 2 degraded oil producing step ST1 is performed, the degraded oil is produced in 2 stages by using the lubricating oil 1 in an amount of 120(g) in total as a sample. This enables the generation of a sufficient amount of deteriorated oil to be used in the RPVOT test step ST2A and the sludge amount measurement step ST2B, which will be described later.

In the degraded oil producing step ST1, the predetermined temperature Tref of the constant temperature bath 13 is set to 150 ℃. By setting the predetermined temperature of the thermostatic bath 13 to 150 ℃ higher than 120 ℃ in the Dry TOST test in this way, oxidation of the lubricating oil 1 can be accelerated. The predetermined temperature Tref of the thermostatic bath 13 may be 130 ℃ to 150 ℃. By setting the predetermined temperature Tref to 130 ℃ or higher, the temperature can be increased by 10 ℃ from 120 ℃ in the Dry TOST test, and it can be said that the oxidation of the lubricating oil 1 can be appropriately accelerated. Further, by setting the predetermined temperature Tref to 150 ℃ or lower, thermal decomposition occurs in the lubricating oil, and the possibility of degradation in a mode different from the degradation due to the expected oxidation can be reduced.

In the degraded oil producing step ST1, the predetermined pressure Pref of the oxygen partial pressure of the pressurized container 11 based on the injection of oxygen is set to 0.62MPa higher than the value under atmospheric pressure. By thus pressurizing the partial pressure of oxygen in the pressurized container 11 to a value higher than the atmospheric pressure as the test condition of the Dry TOST test, the oxidation of the lubricating oil 1 can be accelerated. The predetermined pressure Pref may be a value in the range of 0.3(MPa) to 1.0 (MPa). Instead of oxygen, air may be injected to set the oxygen partial pressure of the pressurized container 11 to the predetermined pressure Pref. The inside of the pressure vessel 11 may be replaced with oxygen, that is, the entire inside of the pressure vessel 11 may be set to an oxygen atmosphere.

As the copper catalyst 12, a coiled copper wire having a diameter (. phi.) of 1.6mm and a length of 3m was used.

Next, an implementation time t for generating the deteriorated oil with different RPVOT residual rates in the deteriorated oil generation step ST1 will be described with reference to fig. 4. Fig. 4 is an explanatory diagram showing an example of a change in pressure in the pressurized container according to the execution time of the degraded oil producing step. As shown in the drawing, after the degraded oil producing step ST1 is started (after the pressurized container 11 is immersed in the thermostat 13), the pressure in the pressurized container 11 becomes the maximum pressure P_maxIf the deteriorated oil generation step ST1 is further continued, the pressure starts to decrease at a certain time point. That is, the oxygen in the pressurized container 11 is consumed by oxidation of the lubricating oil 1, and the pressure in the pressurized container 11 decreases. Here, the pressure in the pressurized container 11 from the start is set from the maximum pressure P_maxTo a preset pressure P_AThe time until this is called the RPVOT value t in the degraded oil generation step ST1_A. In the present embodiment, the preset pressure P_AFrom the maximum pressure P_maxA value of 0.175 MPa. In addition, a preset pressure P_AFor example, may be from a maximum pressure P_maxThe value of 0.170MPa to 0.180MPa is reduced. The RPVOT value t can be determined by_AThat is, under the test conditions of the degraded oil producing step ST1 shown in fig. 3, the degraded oil producing step ST1 is performed until the pressure in the pressurized container 11 reaches the maximum pressure P_maxPressure P reduced by 0.175MPa_A。

Assuming implementation with respect to the determined RPVOT value t_AThe execution time t is X%_AXStep ST1 of producing degraded oil. In this case, it is possible to estimate the produced deteriorated oil 2_XOf (1) due to oxidationThe deterioration is continued only until the deteriorated oil generation step ST1 reaches the RPVOT value t_ATo produce deteriorated oil 2_AX% of (C). As described above, the RPVOT residual ratio which is an index of the degree of degradation of the degraded oil is 100% in the fresh oil, and the value becomes smaller as the degree of progress of oxidation becomes larger. The deteriorated oil generation step ST1 is considered to be continued up to the RPVOT value t_ATo produce deteriorated oil 2_ASince the oxidation of (2) is completed, it can be estimated that the RPVOT residual ratio thereof is approximately 0% (for example, in the range of 0% to 3% or less). I.e. here the RPVOT value t_AIn order to be driven from a maximum pressure P by the pressure in the pressurized container 11_maxDown to a predetermined pressure P_AThe estimated value of the RPVOT residual rate is approximately 0% in period 1. Therefore, it can be estimated that the deterioration by oxidation proceeds only to the deteriorated oil 2_AX% of deteriorated oil 2_XThe residual rate of RPVOT is (100-X)%. Will be directed to the degraded oil 2_xThe estimated value of the RPVOT residual rate (c) is an estimated RPVOT residual rate (%). For example, in FIG. 4, the implementation is relative to the RPVOT value t_ADegraded oil 2 produced in the degraded oil producing step ST1 for a period of time when X is 75%_XThe estimated RPVOT residual ratio (X75%) was 25%. Thus, if implemented with respect to the RPVOT value t_AThe implementation time t is X%_AXThat is, in the deteriorated oil generation step ST1 in the 2 nd period shorter than the 1 ST period, the deteriorated oil 2 that becomes the desired estimated RPVOT residual rate can be generated_X. In other words, the implementation time t is the 2 nd period_AXAccording to the degraded oil 2 to be produced_XThe value of the RPVOT residual rate of (a) is adjusted.

Fig. 5 is an explanatory diagram showing an example of the relationship between the estimated RPVOT residual rate and the actual RPVOT residual rate. The actual RPVOT residual ratio is the ratio of each degraded oil 2 generated in the degraded oil generation step ST1_XAnd a value measured by the RPVOT test defined in ASTM D2272 described later. As illustrated, the inferred RPVOT residual rate and the actual RPVOT residual rate are not values that completely coincide but are close to each other. Therefore, it is possible to obtain the deteriorated oil 2 which is relatively close to the deteriorated oil having the RPVOT remaining rate desired to be obtained in the RPVOT test step ST2A and the sludge amount measurement step ST2B in the subsequent steps_X。

As shown in fig. 5, it is estimated that the RPVOT residual rate has a linear relationship with the actual RPVOT residual rate. Therefore, when at least 2 points shown in fig. 5 are acquired, the RPVOT residual rate is estimated by adjusting the linear relationship, and thus degraded oil close to the RPVOT residual rate at which data is desired to be acquired in the subsequent step can be generated more accurately. As a result, for example, only a part of the degraded oil may be generated in the degraded oil generation step ST1, the generated degraded oil may be subjected to the RPVOT test step ST2A described later to obtain 2 points shown in fig. 5, and then the degraded oil generation step ST1 may be performed again while the RPVOT residual rate is estimated by linear relationship adjustment, thereby generating the remaining degraded oil more accurately.

Next, the worker performs the RPVOT test step ST2A and the sludge amount measurement step ST 2B. The RPVOT test step ST2A and the sludge amount measurement step ST2B may be performed in parallel, or may be performed sequentially from either step. The RPVOT test step ST2A and the sludge amount measurement step ST2B are not steps that cannot be performed until all of the degraded oil is produced in the degraded oil production step ST 1. The RPVOT test step ST2A and the sludge amount measurement step ST2B may be performed when at least 1 type of deteriorated oil is produced.

The RPVOT test step ST2A is a step of measuring the RPVOT residual rate of a part of the produced deteriorated oil by the RPVOT test defined in ASTM D2272. The RPVOT test step ST2A was performed using 1 of the deteriorated oils having the same RPVOT residual ratio among the 2 groups generated in the deteriorated oil generation step ST 1. The RPVOT test step ST2A is performed by the RPVOT test apparatus 10 shown in fig. 2. However, the deteriorated oil generation step ST1 and the RPVOT test step ST2A need not be performed by a single RPVOT test apparatus 10.

RPVOT test step ST2A was carried out according to the test conditions for the RPVOT test specified in ASTM D2272 shown in the right column of fig. 3. More specifically, in the RPVOT test step ST2A, 50g of 1-group deteriorated oil produced in the deteriorated oil production step ST1, 5ml of water, and the coiled copper catalyst 12 having a diameter (Φ) of 1.6mm and a length of 3m were charged into the pressurized vessel 11. Next, the inside of the pressurized container 11 was set to an oxygen atmosphere by oxygen substitution, the pressure inside the pressurized container 11 (i.e., oxygen pressure) was set to 0.62MPa higher than the value under atmospheric pressure, the pressurized container 11 was immersed in the thermostatic bath 13 at 150 ℃, and the pressurized container 11 was rotated in the thermostatic bath 13 by power from a drive source (not shown). Then, the RPVOT value, which is the time from the time when the pressurized container 11 was immersed in the thermostatic bath 13 to the time when the pressure in the pressurized container 11 decreased from the maximum pressure by 0.175MPa, was measured. That is, the oxygen in the pressurized container 11 is consumed by further oxidation of the deteriorated oil, whereby the pressure in the pressurized container 11 decreases. Therefore, the more oxidized the original deteriorated oil, the shorter the time required for the RPVOT test, and the smaller the RPVOT value.

In the RPVOT test step ST2A, an RPVOT test was performed under the test conditions shown in fig. 3 for all the types of degraded oils having different RPVOT residual rates generated in the degraded oil generation step ST1, and the RPVOT value was measured. In the RPVOT test step ST2A, an RPVOT test was also performed on the new oil of the lubricating oil 1 under the test conditions shown in fig. 3, similarly to the deteriorated oil, to measure the RPVOT value. From this, the actual RPVOT residual rate (%) of each deteriorated oil was calculated by dividing the RPVOT value of each deteriorated oil measured by the RPVOT value of the new oil. That is, the RPVOT residual rate is the ratio of the RPVOT value of the deteriorated oil to the RPVOT value of the new oil. As described above, the RPVOT residual ratio is 100% in the fresh oil, and the value is smaller as the degree of progress of the degradation by oxidation is larger. The RPVOT test step ST2A may be performed according to a standard other than ASTM D2272, as long as the actual RPVOT residual ratio (%) of the degraded oil can be measured.

The sludge amount measuring step ST2B is a step of measuring the weight of sludge, which is filter residue, with respect to the remaining part of the produced deteriorated oil. The sludge amount measuring step ST2B was performed using the remaining 1 group, which was not used in the RPVOT test step ST2A, of the deteriorated oils having the same RPVOT residual rate of the 2 groups generated in the deteriorated oil generating step ST 1. The sludge amount measuring step ST2B measures the weight of the sludge for all the types of the deteriorated oil having different RPVOT residual rates generated in the deteriorated oil generating step ST 1. More specifically, in the sludge amount measuring step ST2B, sludge as filtration residue is obtained by subjecting each degraded oil to filtration treatment by a not-shown filtration device, and the weight of the obtained sludge (hereinafter referred to as the amount of sludge) is measured.

When both the RPVOT test step ST2A and the sludge amount measurement step ST2B are completed, the worker performs a determination step ST 3. The determination step ST3 is a step of correlating the measured RPVOT residual rate and the amount of sludge to determine the easiness of generation of sludge due to deterioration of the lubricating oil 1. In the present embodiment, the RPVOT residual rate of each deteriorated oil measured in the RPVOT test step ST2A and the sludge amount of each deteriorated oil measured in the sludge amount measurement step ST2B are correlated with each other, and the sludge amount is plotted for each RPVOT residual rate, thereby determining the sludge formability according to the degree of deterioration of the lubricating oil 1.

Fig. 6 is an explanatory diagram showing an example of the relationship between the RPVOT residual rate measured in the RPVOT test step and the amount of sludge measured in the sludge amount measurement step. In fig. 6, a portion other than the real measurement point is interpolated by a known interpolation method (interpolation method). In fig. 6, as a comparative example, the relationship between the RPVOT residual rate and the amount of sludge when the deteriorated oil was generated by the Dry TOST test under the test conditions in the left column of fig. 3 in place of the deteriorated oil generation step ST1 is also plotted. The amount of sludge in the figure is the amount of sludge (mg) per 1kg of the deteriorated oil.

As shown in the drawings, the relationship between the RPVOT residual rate and the amount of sludge measured in the method for determining sludge formation in oil according to the present embodiment shows a trend of change substantially similar to that of the comparative example. In the example shown in fig. 6, at an RPVOT residual rate of 25%, which is an example of a determination criterion described later, the amount of sludge in the method for determining sludge formation in oil according to the embodiment was 75.8mg/kg, and the amount of sludge in the comparative example was 68.Omg/kg, and almost similar values were obtained. In the example shown in fig. 6, the deviation between the embodiment and the comparative example was 11.5%. It can be said that the method for determining sludge formation in oil according to the present embodiment can determine the ease of formation of sludge according to the degree of degradation of the lubricating oil 1 with an accuracy close to that of the comparative example in the case of producing degraded oil by the Dry TOST test.

As an example of a criterion for determining whether the sludge is easily generated according to the degree of deterioration of the lubricating oil 1, the amount of sludge is less than a predetermined value in a region less than a predetermined RPVOT residual rate. The predetermined RPVOT residual ratio can be, for example, 25% which is the standard of turbine lubricant oil defined in ASTM D4378. The predetermined value of the amount of sludge can be, for example, 100mg/kg, depending on the actual condition that a failure due to sludge such as clogging of a filter occurs in an actual turbine.

An acceleration effect of the deteriorated oil generation by the method for determining the sludge formation of oil according to the embodiment will be described with reference to fig. 7. Fig. 7 is an explanatory diagram showing an example of the execution time required until the degraded oil having a different RPVOT residual rate is generated in the degraded oil generation step. The RPVOT residual rate here is the actual RPVOT residual rate measured in the RPVOT test step ST 2. In fig. 7, a portion other than the real point is interpolated by a known interpolation method (interpolation method). In fig. 7, as a comparative example, values when the deteriorated oil was generated by the Dry TOST test under the test conditions in the left column of fig. 3 are also plotted, similarly to fig. 6. As shown in the figure, 467 hours were required until the RPVOT residual ratio of the deteriorated oil, which is an example of the above-described determination criterion, reached 25%. In contrast, in the method for determining sludge formation in oil according to the embodiment, it takes only 19.7 hours until the RPVOT residual rate of the deteriorated oil reaches 25%. Therefore, according to the deteriorated oil generation step ST1 of the present embodiment, deterioration can be accelerated by 23.7 times as compared with the comparative example.

As described above, in the method for determining sludge formation in oil according to the embodiment, in the degraded oil formation step ST1, the lubricating oil 1 is oxidized at the predetermined pressure Pref having a higher partial oxygen pressure than the atmospheric pressure by replacing oxygen or injecting oxygen or air with oxygen, and thus, the degraded oil can be obtained quickly. Then, the RPVOT residual rate is measured in the RPVOT test step ST2A for a part (1 group amount) of the produced deteriorated oil, and the sludge amount is measured in the sludge amount measurement step ST2B for the remaining part (1 group amount). This makes it possible to measure the RPVOT residual rate and the amount of sludge of the deteriorated oil in parallel. As a result, the obtained RPVOT residual rate and the sludge amount are correlated with each other, and the sludge-prone property due to degradation of the lubricating oil 1 can be determined more quickly.

The predetermined pressure Pref is preferably 0.3(MPa) or more and 1.0(MPa) or less. The predetermined pressure Pref is more preferably 0.62 (MPa).

With this structure, the deteriorated oil can be quickly obtained in the deteriorated oil producing step ST 1. However, the predetermined pressure Pref may be a value higher than the atmospheric pressure and capable of sufficiently accelerating the oxidation of the lubricating oil 1.

The predetermined temperature Tref is preferably 130 (deg.c) or more and 150 (deg.c) or less. Further, the predetermined temperature Tref is more preferably 150 (deg.c).

With this structure, the deteriorated oil can be quickly obtained in the deteriorated oil producing step ST 1. However, the predetermined temperature Tref may be a value that can accelerate oxidation of the lubricant oil 1 more than in the conventional Dry TOST test and is lower than a temperature at which the lubricant oil 1 can be degraded by a degradation mode other than oxidation.

And is pressurized from the maximum pressure P by the pressure in the pressurized container 11_maxDown to a predetermined pressure P_AThe 1 st period (RPVOT value t) in which the estimated value of the RPVOT residual rate is approximately 0 (%) is determined_A) The deteriorated oil generation step ST1 is performed for a 2 nd period (execution time t) shorter than the 1 ST period_AX) In the second period 2, the RPVOT residual rate of the degraded oil to be produced is adjusted.

With this configuration, in the degraded oil producing step ST1, only the 2 nd period (the implementation time t) is adjusted_AX) It is possible to accurately generate a degraded oil close to a desired RPVOT residual ratio. However, the method of determining the implementation time t is not limited to the method described in the present embodiment. For example, the relationship between the execution time t and the actual RPVOT residual rate of the produced deteriorated oil may be accumulated as data in advance by the conventional execution results and experiments of the method for determining the sludge formation of oil according to the embodiment for a specific type of lubricating oil 1, and the execution time t may be set based on the accumulated data so as to obtain a desired RPVOT residual rate. Further, based on the above-described accumulated data, it is possible to perform, for a specific type of lubricating oil 1,the pressure P at which the RPVOT residual rate reaches a predetermined residual rate, for example, approximately 0 (about 3% or less) is predetermined_ARPVOT value t_A。

Then, the deteriorated oil generation step ST1 generates deteriorated oil using the RPVOT test apparatus 10 used in the RPVOT test.

With this configuration, since both the degraded oil producing step ST1 and the RPVOT test step ST2A can be performed by using the RPVOT test apparatus 10 used for the RPVOT test, it is not necessary to prepare a plurality of kinds of test apparatuses, and cost reduction can be achieved. As described above, it is not necessary to use a single RPVOT test apparatus 10 in the degraded oil producing step ST1 and the RPVOT test step ST 2A. The deteriorated oil generation step ST1 may be performed by a device different from the dedicated device used in the RPVOT test, as long as the processing contents described in the present embodiment can be performed.

Description of the symbols

1-lubricating oil, 10-RPVOT test device, 11-pressurized container, 12-copper catalyst and 13-thermostatic bath.