JPH09318526A - Water-in-oil detector and measuring method of water-in-oil quantity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-in-oil detector and a measuring method of water- in-oil quantity which can accurately measure the quantity of water in oil by simple constitution. SOLUTION: A water-in-oil detector is provided with a transparent hollow tube cell 1, a projecting part 2 arranged on one side of the hollow tube cell 1, and a light receiving part 3 arranged on the other side of the hollow tube cell 1, facing the projecting part 2. Oil to be measured is supplied to the hollow tube cell 1, and the quantity of water content in oil is detected by measuring the quantity of light in the light receiving part 3. The projecting part 2 has a first measuring light source 4a generating a light in the wavelength region of 1.3-1.6μm, and a second measuring light source 4b for comparison which generates a light in the wavelength region of 0.8-1.1μm. The quantity of water content in oil to be measured is determined from the difference between the absorbance of the light from the first measuring light source 4a which is caused by the oil to be measured and the absorbance of the light from the second measuring light source 4b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to water contained in various oils such as hydraulic oils, electrical insulating oils, lubricating oils for refrigerators, solvents, petroleum products such as fuels and petrochemical raw materials. The present invention relates to a moisture detector in oil for detecting the amount and a method for measuring the amount of moisture contained in various oils.

[0002]

2. Description of the Related Art For example, the hydraulic fluid used in hydraulic equipment has a significantly deteriorated performance if the oil contains water. Therefore, the amount of water is constantly or periodically measured to obtain a predetermined amount. When it comes to contain the above water, it is necessary to stop using the hydraulic oil. Similarly, electrical insulating oils are also dewatered by a suitable means such as a dehydrating agent or a vacuum oil purifier at the time of shipment at a refinery in order to dislike the inclusion of moisture in the oil. Monitors moisture. Also, in electrical equipment such as oil-filled transformers and oil-filled transformers used in substations, power plants, and the like, moisture monitoring is an important item for preventive maintenance of electrical equipment.

[0003] In recent years, the lubricating oil used for refrigerators, air conditioners for automobiles and the like has been inevitably changed in refrigerant in view of the regulation of chlorofluorocarbons. And PAG (polyalkylene glycol). It is known that these synthetic lubricating oils have higher hygroscopicity than mineral oils, and excessive moisture absorption causes hydrolysis or oxidative deterioration, resulting in reduced lubricating properties and hindering normal operation of machines. Also, for example, for jet fuel, when an aircraft flies through the stratosphere,
It is known that when moisture is contained, it freezes and clogs the fuel line. For these reasons, there is an increasing need to detect the amount of water contained in lubricating oil and other various petroleum products.

In order to detect such moisture in oil,
For example, in Japanese Patent Laid-Open No. 5-107182, as schematically shown in FIG. 2 attached to the present application, a transparent hollow tube cell 1, a light projecting section 2 arranged on one side of the hollow tube cell 1, and a hollow On the other side of the tube cell 1, there is provided a light projecting section 2 and a light receiving section 3 arranged so as to face the hollow cell 1, and the oil to be measured is caused to flow through the hollow tube cell 1, and
There has been proposed a water-in-oil detector that can detect the amount of water in oil by measuring the amount of light.

That is, assuming that the light intensity of the light projecting section 2 is P _O and the light intensity received by the light receiving section 3 is P, the following formula is established: Absorbance = log (P _O / P). If P _O is constant, P changes depending on the amount of water in the oil.

It is conventionally known that water has a light absorption characteristic of near infrared light near 1.45 μm.
Further, as described above, the light projecting section 2 projects near-infrared light of 1.45 μm onto the hollow tube cell 1, and the light receiving section 3 projects it.
When the amount of light passing through the oil flowing through the inside is measured, there is a correlation between the amount of light detected by the light receiving unit 3 and the amount of water in oil, and therefore, from the amount of light measured by the light receiving unit 3, The water content in oil is required.

[0007]

However, according to the results of the research and experiment conducted by the present inventors, oils having various water contents in a near infrared spectrophotometer (NIR) were actually used. It was found that the spectrum shown in Fig. 3 was obtained. The sample oil used at this time was hydraulic oil.

As can be seen from the spectrum of FIG. 3, comparing the case where the water content is approximately 0% and the case where the water content is approximately 5%, the absorption of 1.45 μm, which is considered to be the absorption of water, is found. In addition to the inherent absorption of water, the increase in the baseline due to the emulsion and the absorption peak of the oil are added, and as in the conventional case, simply 1.45 μm from the light projecting unit 2.
It was found that an accurate amount of water in oil cannot be obtained by projecting the near-infrared light of No. 3 onto the hollow tube cell 1 and determining the amount of water in oil from the amount of light measured by the light receiving unit 3.

Further, as a result of detailed analysis of the spectrum shown in FIG. 3, the increase of the baseline around 1.45 μm is almost the same as other absorption bands, and in reality, for example, 950 nm (0.95 μm). It was found that the amount of water in the oil can be measured extremely accurately by setting the absorbance of to the size of the baseline itself.

The present invention has been made based on the novel findings of the present inventors.

Therefore, an object of the present invention is to provide a simple structure,
An object of the present invention is to provide a moisture detector in oil that can accurately measure the moisture content in oil and a method for measuring the moisture content in oil that can accurately measure the moisture content in oil.

[0012]

The above object can be achieved by the water-in-oil detector according to the present invention. In summary, the present invention comprises a transparent cell, a floodlight disposed on one side of the cell,
On the other side of the cell, a light receiving section is arranged opposite to the light projecting section, the oil to be measured is supplied to the cell, and the light quantity of the light receiving section is measured to detect the water content in the oil. In the water-in-oil detector that can be used, the light emitting unit has a wavelength range of 1.
Moisture detection in oil, comprising a first measurement light source that emits light of 3 to 1.6 μm and a second measurement light source for comparison that emits light of wavelength range 0.8 to 1.1 μm. It is a vessel. Preferably, the light projecting section has a center wavelength of 1.4 to 1.5.
A first measurement light source that emits light of μm and a center wavelength of 0.9
A second measuring light source for comparison, which emits light of ˜1.0 μm, or more preferably, the first measuring light source is a light emitting diode which emits light having a center wavelength of 1.45 μm ± 0.03 μm, The center wavelength of the second measurement light source is 0.94 μm
It is a light emitting diode that emits light. The cell is a hollow tube cell.

In the present invention, the first measuring light source is used to obtain information on the water content, and the second measuring light source is used to obtain information on the variation of the baseline contained in the water content information. To be done.

The above object is also achieved by the method for measuring the water content in oil according to the present invention. In summary, the difference between the absorbance of the first light in the wavelength range of 1.3 to 1.6 μm and the absorbance of the second light in the wavelength range of 0.8 to 1.1 μm of the oil to be measured The method for measuring the water content in oil is characterized in that the water content in the oil to be measured is determined. In addition, by comparing the difference between the absorbance of the first light and the absorbance of the second light with the previously measured correlation between the oil to be measured and the water content, the water content in the oil can be determined. It is a method for measuring the water content in oil, which is characterized in that it is determined. Preferably, the wavelength range of the first light is 1.4 to 1.5 μm.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The water-in-oil detector according to the present invention will be described below in more detail with reference to the drawings.

FIG. 1 shows an embodiment of the water-in-oil detector of the present invention. In this embodiment, the water-in-oil detector has a hollow tube cell 1 made of a transparent material such as quartz glass, and a light projecting section 2 and a light receiving section are provided in a direction orthogonal to the axis of the hollow tube cell 1. Part 3
And are arranged facing each other. Oil to be measured is supplied into the hollow tube cell 1.

In particular, according to the present invention, the light projecting section 2 is provided with a first measuring light source 4a and a second measuring light source 4b.
The first measurement light source 4a is a measurement light source used to obtain information on the water content, and generally has a wavelength range of 1.3.
~ 1.6 μm, preferably with a center wavelength of 1.4-1.5 μm
m light source. According to the present invention, contained in oil,
In general, the purpose is to detect and measure water having a water content of 0.1% to 10% (by weight),
Further, since water has a characteristic light absorption around 1.45 μm, the wavelength range of the first measurement light source 4a is 1.3 to
When it is extended to outside the range of 1.6 μm, information on other components contained in oil may be detected, which adversely affects the detection accuracy of water content, which is not preferable.
1.4-1.5μ where the absorption of light due to moisture appears clearly
It is possible to detect with high accuracy by measuring in the wavelength range of m.

The second measuring light source 4b is a measuring light source for comparison, which will be described later in detail, and is used to obtain information about the fluctuation of the baseline included in the information about the water content. Wavelength range of 0.8 ~
1.1 μm, preferably with a center wavelength of 0.9 to 1.0 μm
It is used as a light source. Since the second measurement light source 4b corrects the baseline information included in the information regarding the water content obtained by the first measurement light source 4a, the wavelength of the second measurement light source 4b is 0.8 to If the thickness is out of the range of 1.1 μm, information other than the baseline information may be included, which also adversely affects the detection accuracy of the water content, which is not preferable.

That is, FIG. 4 shows the relationship between the deterioration of the lubricating oil, the absorbance and the wavelength. As shown, the wavelength is 0.7 μm.
It can be seen that in a region smaller than m, the absorbance changes greatly as the oil deteriorates. Therefore, it is not suitable to use a wavelength in the wavelength region smaller than 0.7 μm as the wavelength for the second measurement light source, and it is preferable to use a wavelength of 0.8 μm or more. However, in the wavelength region larger than 1.1 μm, as shown in the figure, there is a wavelength exhibiting a specific absorbance for a certain oil component, and the wavelength for the second measurement light source for comparison is 1 It is preferred to use wavelengths below 0.1 μm.

As described above, the wavelength range is practically 0.8 to
By setting the absorbance of 1.1 μm to the size of the baseline itself, the water content in the oil can be measured extremely accurately. Therefore, the center wavelength of the second measurement light source 4b is 0.9 to It is set to 1.0 μm.

In this embodiment, the first measuring light source 4a has a center wavelength of 1.45 μm ± 0.03 μm and a maximum light amount value of 50.
% Light emitting diode (LED) (made by Shimadzu Corporation: trade name HK-)
9321), the second comparative measurement light source 4b is a light emitting diode (L) having a center wavelength of 0.94 μm and a wavelength range of 0.92 to 0.96 μm at 50% of the maximum light amount value.
ED) (manufactured by Toshiba Corporation: trade name TLN110) was used to obtain good results.

Further, in the present embodiment, the first and second measuring light sources 4a and 4b are connected to the constant current power sources 5a and 5b, respectively, so as to emit light of a constant intensity.

FIG. 3 is a spectrum of the hydraulic oil containing water of various water contents, which is taken by the near infrared spectrophotometer as described above.

As can be seen from the spectrum of FIG.
When the spectrum of the water content in oil of 63.6 ppm, that is, the water content of substantially 0% was compared with the water content of 5.04%, that is, about 5%, it was found that the water absorption was 1. 45 μm
The absorption (A _T ) of A is obtained by adding the increase of the baseline BL and the absorption peak A _{H of} oil in addition to the original absorption of water. Also, the increase in the baseline around 1.45 μm is almost the same size as other absorption bands, and in reality, for example, the absorbance of hydrous oil at 950 nm (0.95 μm) can be set to the size of the baseline itself. it can.

Therefore, as shown in FIG. 3, assuming that the absorbance at each absorption position is A _W , A _T , A _H , A _BL , and A _B , that is, the absorbance of true water at A _W : 1.45 μm. , a _T: absorbance at 1.45μm of hydrous oil, a _H: absorbance at 1.45μm moisture content 0% oil, a _BL: absorbance of water oil in 950nm, a _B: water at 950nm content 0% oil Absorbance of, and the following equation theoretically holds from the definition of absorbance. A _W = A _T − (A _H −A _BL + A _B ) (1) A _W = βw (2) Here, w is the water concentration in oil (that is, the amount of water in oil), and β is unique to the system. Is a constant.

A _BL corresponding to the absorbance of the baseline _BL
Although it is not clear why this occurred, the present inventors consider as follows.

That is, when the water content is higher than the solubility in oil as in this system, the water becomes fine particles and W /
It has been confirmed as a result of observation that the dispersion is carried out in the form of an O (water-in-oil type) emulsion, that is, an emulsion in which water is dispersed in oil. As a result of actual measurement by a laser diffraction type particle size distribution measuring device, water particles are 5 to 50 μm.
It was distributed in m. When these particles are exposed to light, the central part is linearly transmitted, but the peripheral part is considered to cause reflection and refraction at the interface, causing apparent scattering.This phenomenon causes optical loss and causes baseline loss. Is expected to occur. The reason why there is almost no wavelength dependency in the rise of the baseline is probably because the particle size of the water particles is large and the influence of the wavelength is small with respect to the wavelength.

Next, the inventors of the present invention used a moisture detector having a structure as shown in FIG. 1 and used three types of oil such as hydraulic oil and lubricating oil as samples in the transparent hollow tube cell 1. (A, B,
C) is made to flow, and the first measuring light source 4 of the light projecting unit 2 is
The center wavelength from the light emitting diode of a is 1.45 μm ± 0.0
The wavelength range at 3 μm and 50% of the maximum light intensity value is 1.4 to 1.
The light of 5 μm is emitted from the light emitting diode of the second comparative measurement light source 4b with the center wavelength of 0.94 μm and the maximum light intensity value of 50.
% Light having a wavelength range of 0.92 to 0.96 μm is projected onto the hollow tube cell 1, and the photodiodes (PD) 6a and 6b as the photodetectors of the light receiving section 2 respectively receive the hollow tube cell. 1
The amount of light that passed through the flowing sample was measured. Then, the water content in oil (wt%) and the absorbance difference (A _W ) were obtained. The result is shown in the graph of FIG. From FIG. 5, it can be seen that there is a linear correlation between the water content in oil (wt%) and the absorbance difference (A _W ). That is, if the sample oil is measured and the difference in absorbance (A _W ) is determined, based on the previously known correlation diagram shown in FIG. 5 or the equation shown in the above equation (1) or (2), The water content in the oil at that time can be easily and accurately determined.

Further, the water-in-oil detector of the present invention has a structure as shown in FIG. 6, for example, which automatically displays the amount of water in oil on a display device or prints it on a printer. Can be output.

That is, the water-in-oil detector has an electronic circuit for converting the amount of light received by the light receiving section 3, that is, the photodiodes 6a and 6b into an electric signal. As the electronic circuit, a voltage detection circuit 21 (21a, 21b) for frequency-converting the amount of light detected by the light receiving unit 3 as disclosed in JP-A-4-324328 proposed by the present applicant is preferably used. be able to. The voltage detection circuit 21 will be briefly described with reference to FIG.

FIG. 6 is a block diagram showing the basic configuration of the voltage detection circuit 21. In this embodiment, the capacitors C (Ca, Cb) are connected in series with the photodiodes 6a, 6b as the photodetectors of the light receiving section 3 and are output from the photodiodes 6a, 6b in proportion to the amount of incident light. The accumulated currents I _Pa and I _Pb are stored in the capacitors Ca and _Cb and converted into voltages V _Ca and V _Cb . The charging voltages V _Ca and V _Cb are detected by the voltage detection circuit 21 (21a and 21b) and compared with a preset reference voltage. When the charging voltage reaches the reference voltage, the voltage detection circuits 21a and 21b output signals. Change the level. Due to this change in signal level, the capacitor C
The electric charges accumulated in a and Cb are discharged, and the capacitor C is caused to start accumulating the output current I _P from the photodiode PD again. In this way, the voltage detection circuit 21
Frequency signals corresponding to the light intensity received by the light receiving unit are output from a and 21b.

The respective frequency signals from the voltage detection circuit 21 thus converted according to the light quantity are calculated and measured by the calculation and measurement means 2.
At 2, the arithmetic processing is performed based on the arithmetic expressions shown in the above equations (1) and (2), and converted into the number of pulses according to the amount of water in oil. This output pulse from the calculation and measurement means 22 is transmitted to the display means 23 and displayed as the water content in oil on the display device or printed out by the printer and output. If desired, the display means 23 may be provided with an alarm device so as to issue an alarm when the amount of water in oil reaches a specified amount.

7 and 8 show the construction of a portable type moisture-in-oil detector which is another embodiment of the present invention. According to this embodiment, the water-in-oil detector includes the detection unit 1
00 and the main body 200, the detection unit 100 includes a pair of elongated rods 100A and 100B, the length of which can be arbitrarily set according to the application. For example, it may be 1 to 2 m. Also, rods 100A, 100B
The sensor heads 101A and 101B are respectively attached to the tips of the
Is provided. One of the sensor heads 101A is a hollow tube cell 1a made of a transparent material such as quartz glass.
And a light receiving section having a first measuring light source 4a such as an LED in a direction orthogonal to the axis of the hollow tube cell 1a, and a light receiving section having a photodetector 6a such as a photodiode. Are arranged facing each other. In addition, the other sensor head 101B is also provided with a hollow tube cell 1b made of a transparent material such as quartz glass, and the first tube such as an LED is arranged in a direction orthogonal to the axis of the hollow tube cell 1b. A light projecting unit having two measuring light sources 4b and a light receiving unit having a photodetector 6b such as a photodiode are arranged to face each other. In the water-in-oil detector of this embodiment, the sensor heads 101A and 101B are immersed in the oil to supply the oil into the hollow tube cells 1a and 1b.

The main body 200 is provided with the voltage detection circuit 21 (21a, 21b) as described with reference to FIG. 6, the arithmetic and measurement means 22, the display means 23, and other electronic circuit parts, and the power switch 201. By operating the, the amount of water in oil is displayed on the window 202 of the display device as the display means 23.

The hollow tube cell 1 in each of the above-mentioned embodiments used in the present invention is capable of passing near-infrared light of a specific wavelength band from the light projecting portion, that is, light rays of 1.45 μm and 0.95 μm. Any material may be used as long as it is extremely transparent to the near infrared light such as FEP (tetrafluoroethylene-hexafluoropropylene copolymer resin) other than the above-mentioned quartz glass. It can be made of a good fluororesin (about the same as glass). As the hollow tube cell 1, a circular hollow tube having an outer diameter of 2 to 10 mm and an inner diameter of 1 to 8 mm is suitable.

Although a hollow tube cell was used in the above embodiment, the cell of the present invention is not limited to a hollow tube cell, and a transparent or semitransparent parallel plate, an infrared analysis glass cell, and a red cell are used. Cells such as transparent plastic cells for external analysis can also be used.

[0037]

As described above, the water-in-oil detector of the present invention has a transparent cell, a light projecting section arranged on one side of the cell, and the light projecting section facing the other side of the cell. In the oil moisture detector, which is equipped with a light receiving section that is placed in the cell, supplies the oil to be measured to the cell and measures the light quantity of the light receiving section to detect the water content in the oil. The section includes a first measurement light source that emits light having a wavelength range of 1.3 to 1.6 μm,
A second measuring light source for comparison, which emits light having a wavelength range of 0.85 to 1.1 μm, is provided. In particular, the first measuring light source is used to obtain information regarding the water content, and the second measuring light source is used. The measurement light source of is used to measure the water content in the oil used to obtain the information about the fluctuation of the baseline included in the information about the water content, so that the water content in the oil can be accurately measured with a simple configuration. Can be measured.

The method for measuring the water content in oil of the present invention is as follows:
From the difference between the absorbance of the first light in the wavelength range of 1.3 to 1.6 μm and the absorbance of the second light in the wavelength range of 0.8 to 1.1 μm of the oil to be measured, the measurement is performed. It is a method of determining the water content in the oil to be determined, and in particular, the water content in the oil is determined by comparison with the correlation between the oil to be measured and the water content that has been measured in advance. Therefore, it is possible to easily and accurately measure the water content in the oil.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a water-in-oil detector of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a conventional moisture detector.

FIG. 3 is a spectrum diagram of hydraulic oil containing water having various water contents, which is taken by a near infrared spectrophotometer.

FIG. 4 is a diagram showing the relationship between oil deterioration, absorbance and wavelength.

FIG. 5 is a diagram showing the correlation between the amount of water in oil and the absorbance difference obtained by the water-in-oil detector of the present invention.

FIG. 6 is a block diagram showing an embodiment of an electronic circuit configuration of the water-in-oil detector of the present invention.

FIG. 7 is a front view showing a schematic configuration of another embodiment of the water-in-oil detector of the present invention.

8 is a side view of the water-in-oil detector of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 cell 2 light emitting part 3 light receiving part 4a first measurement light source 4b second measurement light source 6 (6a, 6b) photodetector 21 voltage detection circuit 22 arithmetic and measurement means 23 display means

Claims (8)

[Claims] 1. A cell comprising a transparent cell, a light projecting section arranged on one side of the cell, and a light receiving section arranged on the other side of the cell so as to face the light projecting section, to be measured on the cell. In a moisture detector in oil capable of detecting the amount of water in oil by supplying the oil and measuring the amount of light in the light receiving unit, the light emitting unit emits light in the wavelength range of 1.3 to 1.6 μm. A water-in-oil detector comprising: a first measurement light source that emits light; and a second measurement light source for comparison that emits light having a wavelength range of 0.8 to 1.1 μm. 2. The projection unit has a center wavelength of 1.4 to 1.5 μm.
A first measurement light source that emits m light and a center wavelength of 0.9 to
The water-in-oil detector according to claim 1, further comprising a second measurement light source for comparison, which emits light of 1.0 μm. 3. The first measurement light source has a center wavelength of 1.45.
The water-in-oil detector according to claim 1, which is a light emitting diode that emits light of μm ± 0.03 μm, and the second measurement light source is a light emitting diode that emits light having a center wavelength of 0.94 μm. 4. A first measuring light source is used to obtain information about water content, and a second measuring light source is used to obtain information about baseline fluctuations included in the information about water content. Item 1, 2 or 3 water-in-oil detector. 5. The water-in-oil detector according to claim 1, wherein the cell is a hollow tube cell. 6. The wavelength range of the oil to be measured is 1.3-1.
Absorbance of 6 μm of first light and wavelength range of 0.8 to 1.1
A method for measuring the amount of water in oil, wherein the amount of water in the oil to be measured is determined from the difference from the absorbance of the second light of μm. 7. The wavelength range of the oil to be measured is 1.3-1.
Absorbance of 6 μm of first light and wavelength range of 0.8 to 1.1
The amount of water in the oil to be measured is determined by measuring the difference from the absorbance of the second light of μm and comparing the difference with the previously measured correlation between the oil and water to be measured. The method for measuring the water content in oil according to claim 6, wherein 8. The wavelength range of the first light is 1.4 to 1.5 μm.
The method for measuring the water content in oil according to claim 6 or 7.