JP3688607B2 - Turbine oil deterioration degree evaluation method and deterioration degree evaluation apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for evaluating the degree of deterioration of turbine oil, and more specifically, the degree of deterioration of turbine oil that can measure the absorbance of oxide absorption peaks with good measurement accuracy and can accurately evaluate the degree of deterioration of turbine oil. It relates to the evaluation method.
The turbine oil deterioration degree evaluation method of the present invention is widely used in the evaluation of the deterioration degree of turbine oil used for bearing lubrication and the like of various turbine generators and the related fields.
[0002]
[Prior art]
Conventionally, a method for evaluating the degree of deterioration of turbine oil by measuring the absorbance of an oxide absorption peak (due to the CO group of carboxylic acid, etc.) appearing in the vicinity of a wave number of 1710 cm ^{−1 of the} turbine oil using an infrared absorption spectrum Is known (for example, JP-A-9-96398). Based on the evaluation result of the degree of deterioration of the turbine oil, diagnosis such as the replacement timing of the turbine oil and abnormal wear (lubricant abnormality) of the lubrication target portion has been performed.
[0003]
By the way, in the infrared absorption spectrum method, an assembly type or a fixed type measurement cell is usually used, and turbine oil is injected into the measurement cell to form a sample film having a predetermined thickness, and the infrared spectrum is measured. Is called.
However, the measurement cell has a structure in which a spacer is sandwiched between a pair of frame plates and these are integrally assembled with screws. Sometimes fluctuated. Thus, when the measurement conditions are not so good, there is a problem that the measurement accuracy of the absorbance of the oxide absorption peak is lowered and the deterioration degree of the turbine oil cannot be accurately evaluated.
[0004]
Here, as the infrared absorption spectrum method, a method using a dispersive spectrometer (hereinafter also referred to as IR method) and a method using an interference spectrometer (hereinafter also referred to as FT-IR method) are described. In recent years, the FT-IR method with a shorter measurement time and higher measurement accuracy than the IR method has become widespread. And it tried to evaluate the deterioration degree of turbine oil more correctly using this FT-IR method. However, when the measurement conditions are not so good as described above, the measurement accuracy is lowered even in the FT-IR method.
[0005]
[Problems to be solved by the invention]
In view of the above, an object of the present invention is to provide a turbine oil deterioration degree evaluation method capable of measuring the absorbance of an oxide absorption peak with good measurement accuracy and accurately evaluating the deterioration degree of turbine oil. .
[0006]
[Means for Solving the Problems]
The present inventor has found that the absorption peak (due to the CH group of hydrocarbons) appearing in the vicinity of a wave number of 720 cm ^{−1 in} the infrared spectrum of the turbine oil changes almost with time even when the turbine oil deteriorates under strict measurement conditions. The present invention has been completed by paying attention not to do so.
[0007]
In other words, the turbine oil deterioration degree evaluation method according to claim 1 is a method for evaluating the deterioration degree of the turbine oil by measuring the absorbance of the oxide absorption peak by using an infrared absorption spectrum method. Wave number 700cm ^-1 ~ 750cm ^-1 The change rate from the new oil in the absorbance of the comparative absorption peak existing in the oil is determined, the absorbance of the oxide absorption peak is corrected based on the change rate, and the turbine oil is deteriorated from the corrected absorbance of the oxide absorption peak. It is characterized by evaluating the degree.
[0008]
The turbine oil deterioration degree evaluation method according to claim 2 is characterized in that, in the method according to claim 1, the infrared absorption spectrum method is a method using an interference spectrometer.
[0009]
Moreover, the turbine oil deterioration degree evaluation method according to claim 3 is the method according to claim 1 or 2, wherein the correction is performed based on the correlation between the absorbance of the oxide absorption peak of the turbine oil and the total acid value. A total acid value corresponding to the absorbance of the oxide absorption peak is obtained, and the deterioration degree of the turbine oil is evaluated from the obtained total acid value.
[0010]
According to such a method, even when the measurement conditions are not so good (for example, when the thickness of the measurement cell fluctuates, etc.), the absorbance of the comparative absorption peak is based on the rate of change from the new oil. The absorbance of the oxide absorption peak is corrected to an appropriate value, and the deterioration degree of the turbine oil can be accurately evaluated. Accordingly, there is an advantage that diagnosis of turbine oil replacement timing and abnormal wear (lubrication abnormality) of the lubrication target part can be performed more accurately and quickly.
[0011]
Further, according to the turbine oil deterioration degree evaluation method using the FT-IR method using an interference spectroscope as an infrared absorption spectrum method as described in claim 2, the absorbance of the oxide absorption peak can be measured with better measurement accuracy. This is preferable because it can be measured.
[0012]
Further, according to the turbine oil deterioration degree evaluation method for evaluating the deterioration degree of the turbine oil from the total acid value as described in claim 3, the turbine acid can be easily obtained from the total acid value which has been conventionally used as an evaluation standard for the deterioration degree. This is preferable because the degree of deterioration of the oil can be evaluated.
[0013]
Examples of the “turbine oil” include an additive turbine oil containing an additive (such as an antioxidant, a rust inhibitor, and a defoamer), and an additive-free turbine oil containing no additive. Further, examples of the use of turbine oil include bearing lubrication (mainly sliding bearing lubrication) of a hydro turbine generator, a steam turbine generator, a turbo blower, a turbo compressor, and the like. Typically, non-added turbine oil is used in hydro turbine generators, and added turbine oil is used in steam turbine generators with severe thermal conditions.
The “oxide absorption peak” is an absorption peak that usually appears in the vicinity of a wave number of 1720 cm ^{−1 in} the infrared spectrum of turbine oil. In addition, the above “change rate from new oil” means the change rate of turbine oil after use with respect to unused turbine oil (new oil), as long as the absorbance of the oxide absorption peak can be suitably corrected. The rate of change from the turbine oil in the initial use state may be used. The “total acid value” means the amount of potassium hydroxide required to neutralize 1 g of oil. The total acid value and the absorbance of the oxide absorption peak of the turbine oil (IR oxidation degree) ) Is known to have a proportional relationship (see FIG. 2). The “near wave number 720 cm ⁻¹ ” is usually a wave number of 650 to 800 cm ⁻¹ , preferably a wave number of 700 to 750 cm ⁻¹ .
[0014]
Further, the turbine oil deterioration degree evaluation apparatus according to claim 4 is an apparatus for measuring the absorbance of the oxide absorption peak using an infrared absorption spectrum method to evaluate the deterioration degree of the turbine oil. Wave number 700cm ^-1 ~ 750cm ^-1 A rate-of-change calculating means for calculating a change rate from the new oil in the absorbance of the comparative absorption peak existing in the sample, an absorbance correcting means for correcting the absorbance of the oxide absorption peak based on the calculated rate of change, and the correction And an evaluation means for evaluating the degree of deterioration of the turbine oil from the absorbance of the oxide absorption peak.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to FIGS.
In the turbine oil deterioration degree evaluation method of the present embodiment, the FT-IR method using an interference type spectroscope is used as the infrared absorption spectrum method, and the additive-free turbine used for sliding bearing lubrication of a hydro turbine generator Oil was the subject of evaluation. In the FT-IR method, a computer (not shown) is provided to measure an infrared spectrum by performing a fast Fourier transform on an interference signal (interferogram). The computer realizes functions such as arithmetic processing and comparison processing using measurement data, which will be described later.
[0016]
First, an infrared spectrum of unused turbine oil (new oil) is measured by the FT-IR method. In this infrared spectrum, a comparative absorption peak 2 (due to a hydrocarbon CH group or the like) appears in the vicinity of wave numbers 721 to 722 cm ⁻¹ (see FIG. 3). This comparative absorption peak 2 hardly changes with time under strict measurement conditions. As shown in FIG. 1, the comparative peak height: 0.3462 was measured as the absorbance of the comparative absorption peak 2.
[0017]
Next, the infrared spectrum of the used turbine oil is continuously measured three times at a preset sampling cycle. When turbine oil is oxidized, an oxide absorption peak 1 (due to a CO group of carboxylic acid, etc.) appears in the vicinity of a wave number of 1710 cm ⁻¹ (see FIG. 3). As shown in FIG. 1, the measurement peak height: 0.0126 was measured as the absorbance of the oxide absorption peak 1. Further, as the absorbance of the comparative absorption peak 2, a comparative peak height: 0.4275 was measured.
[0018]
Here, the ratio of the comparison peak height at the time of new oil and the comparison peak height measured this time (change rate from the new oil): about 0.8098 ( 0.3462 ÷ 0.4275 ) is obtained, and based on this ratio Thus, the measured peak height is corrected, and a corrected peak height: 0.01020 ( 0.8098 × 0.0126) is calculated. Such calculation is repeated to obtain three corrected peak heights, and an average value of these corrected peak heights: 0.00973 is calculated. Furthermore, thickness correction is added to this average value, and IR oxidation degree: 0.1946 abs / cm ( 0.00973 × 10 ÷ 0.5) is obtained.
[0019]
Thereafter, the value of the total acid value corresponding to the above IR oxidation degree: 0.1946 abs / cm: 0.09 mgKOH / g based on the correlation between the preset IR oxidation degree and the total acid value (see FIG. 2). Is obtained. At this time, the deterioration degree of the turbine oil is evaluated by comparing the calculated total acid value with an appropriate threshold value set in advance.
[0020]
As described above, in this embodiment, the measured peak height of the oxide absorption peak appearing near the wave number 1710 cm ^{−1 of the} turbine oil is corrected based on the comparative peak height of the comparative absorption peak appearing near the wave number 720 cm ^−1. Therefore, for example, even when the measurement conditions such as the thickness of the measurement cell fluctuate are not so strict, it is possible to calculate a more appropriate IR oxidation degree and accurately determine the deterioration degree of the turbine oil. Can be evaluated. Therefore, it is possible to more accurately and promptly diagnose turbine oil replacement time and abnormal wear (lubricant abnormality) of the lubrication target part. In this example, since the FT-IR method is used as the infrared absorption spectrum method, it is possible to perform a highly sensitive and short-time measurement with respect to a small amount of sample as compared with the IR method, and more advanced spectrum analysis. Etc. can be performed. Further, in this embodiment, based on the correlation between the IR oxidation degree and the total acid value, the value of the total acid value corresponding to the IR oxidation degree is obtained, and whether the calculated value of the total acid value exceeds the threshold value or not is determined. Since the degree of deterioration of the oil is evaluated, the degree of deterioration of the turbine oil can be evaluated more accurately and easily.
[0021]
Next, as a comparative example, an infrared spectrum of diesel engine oil used in an automobile will be described. As shown in FIG. 4, the peak height of the absorption peak 102 near the wave number 720 cm ⁻¹ of the engine oil shows a value that differs greatly between the unused engine oil (new oil) and the used engine oil. The line is very different. Furthermore, an absorption peak 103 that has already interfered with measurement has already appeared in the vicinity of a wave number of 1710 cm ⁻¹ with unused engine oil (new oil). Therefore, it can be seen that even if the degradation degree evaluation method of the present invention is applied to engine oil, there is not much effect.
[0022]
【The invention's effect】
According to the turbine oil deterioration degree evaluation method of the first aspect, even if the measurement conditions are not so good, the turbine oil deterioration degree can be accurately evaluated.
According to the turbine oil deterioration degree evaluation method of the second aspect, in addition to the effect of the method of the first aspect, the deterioration degree of the turbine oil can be more accurately evaluated.
According to the turbine oil deterioration degree evaluation method according to the third aspect, in addition to the effects of the method according to the first or second aspect, the deterioration degree of the turbine oil can be evaluated more accurately and easily.
According to the turbine oil deterioration degree evaluation apparatus of the fourth aspect, even if the measurement conditions are not so good, the deterioration degree of the turbine oil can be accurately evaluated.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining various measurement data according to an FT-IR method of the present embodiment.
FIG. 2 is an explanatory diagram for explaining a correlation between a total acid value and an IR oxidation degree.
FIG. 3 is a diagram showing an infrared spectrum of turbine oil.
FIG. 4 is a diagram showing an infrared spectrum of engine oil of a comparative example.
[Explanation of symbols]
1; oxide absorption peak, 2; comparative absorption peak.

Claims (4)

A method for evaluating the degree of deterioration of turbine oil by measuring the absorbance of an oxide absorption peak using an infrared absorption spectrum method,
Wave number 700cm ^{-1 of the} turbine oil ~ 750cm ^-1 The absorbance change of the comparative absorption peak existing in the oil is determined from the new oil, the absorbance of the oxide absorption peak is corrected based on the change rate, and the turbine oil is deteriorated from the corrected absorbance of the oxide absorption peak. A method for evaluating the degree of deterioration of turbine oil, wherein the degree of deterioration is evaluated.   The turbine oil deterioration degree evaluation method according to claim 1, wherein the infrared absorption spectrum method uses an interference spectrometer.   Based on the correlation between the absorbance of the oxide absorption peak of the turbine oil and the total acid value, a total acid value corresponding to the corrected absorbance of the oxide absorption peak is obtained, and the turbine oil is determined from the obtained total acid value. The turbine oil deterioration degree evaluation method according to claim 1 or 2, wherein the deterioration degree is evaluated. An apparatus for evaluating the degree of deterioration of turbine oil by measuring the absorbance of an oxide absorption peak using an infrared absorption spectrum method,
Wave number 700cm ^{-1 of the} turbine oil ~ 750cm ^-1 A rate-of-change calculating means for calculating a change rate from the new oil in the absorbance of the comparative absorption peak existing in the sample, an absorbance correcting means for correcting the absorbance of the oxide absorption peak based on the calculated rate of change, and the correction And an evaluation means for evaluating the degree of deterioration of the turbine oil from the absorbance of the oxide absorption peak thus obtained.

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