JPWO2018025813A1 - Oil concentration measuring device and oil concentration measuring method - Google Patents

Abstract

Provided is an oil concentration measuring device for cleaning liquid, which does not require the use of an expensive spectral element, a detection element or the like. The oil concentration measuring apparatus 10 irradiates the liquid to be measured (cleaning liquid) with the irradiation light having the measurement wavelength which is a predetermined one wavelength between 280 and 300 nm, and the irradiation light is the liquid to be measured. Based on the transmitted light detection unit 105 that measures the intensity of the transmitted light and the transmitted light intensity measured by the transmitted light detection unit 105, the absorbance at the measurement wavelength of the liquid to be measured is calculated, and the value of the absorbance is calculated. And an oil concentration determination unit 1061 for determining the concentration of the oil in the liquid to be measured based on a calibration curve showing the relationship between the concentration of the oil at the measurement wavelength and the absorbance. There is almost no absorption of molecules that do not have multiple bonds of carbon atoms possessed by hydrocarbon-based cleaning solutions, which are the mainstream of industrial cleaning solutions, and it is possible to detect low concentrations of oil of around 50 ppm between 280-300 nm The use of one wavelength eliminates the need for expensive spectral elements, detection elements, and the like.

Description

  The present invention relates to an apparatus and method for measuring the concentration of oil in a cleaning solution. This oil concentration measuring device and oil concentration measuring method are contained in the cleaning solution during use in an industrial cleaning machine that removes oil such as cutting oil, press / punching oil, machine oil, grease, and flux adhering to the work. It is preferably used to measure the concentration of oil.

  As a cleaning solution used in industrial cleaning machines, a hydrocarbon-based cleaning solution is the mainstream. Hydrocarbon-based cleaning solutions do not contain ozone-depleting substances and chlorine, and therefore have the advantage of having little impact on the environment and human body. In addition, taking advantage of the fact that the boiling point of hydrocarbon is lower than that of the above-mentioned oil component, the hydrocarbon-based cleaning solution stores the hydrocarbon-based cleaning solution containing the used oil component in the distillation tank before the hydrocarbon is stored. It is also possible to carry out distillation regeneration by heating to a temperature higher than the boiling point of the oil and lower than the boiling point of the oil. The hydrocarbon-based cleaning liquid further has a feature that clean vapor generated at the time of the distilling and regeneration treatment can be used for cleaning and drying of a work (hereinafter referred to as “vapor cleaning and drying”). In steam cleaning and drying, the work is stored in a cleaning tank for steam cleaning and drying, the surface of the work is cleaned with the vapor by introducing the steam into the tank, and then the pressure in the tank is reduced rapidly. By sharply lowering the boiling point of the cleaning agent, the cleaning agent adhering to the surface of the work is bumped and vaporized to dry the work. In an actual industrial cleaning machine, after a work is stored in a liquid cleaning tank in which a hydrocarbon cleaning liquid is stored to perform liquid cleaning, steam cleaning and drying are performed for finishing.

  When the industrial washer is operated continuously, the oil removed by distillation gradually accumulates in the distillation tank, and the oil is mixed in the vapor of the hydrocarbon-based cleaning solution (cleaning solution after regeneration) after distillation regeneration. As a result, the oil in the vapor adheres to the surface of the work during vapor cleaning and drying, and the cleaning ability is reduced. In order to prevent such a decrease in the cleaning ability, it is necessary to suppress the oil concentration of the cleaning solution after regeneration to a predetermined concentration or less. The predetermined concentration differs depending on the component of the oil component, but is preferably 50 to 100 ppm or less in order to prevent the decrease in the cleaning ability regardless of the component. Conventionally, the residual liquid in the distillation tank containing oil is removed when the number of times of cleaning of the work reaches the predetermined number determined by the rule of thumb, but if the concentration of oil in the cleaning solution after regeneration is measured, It is expected that the residual liquid can be removed at an appropriate timing.

  For example, it is conceivable to use the method described in Patent Document 1 to measure the oil concentration of the cleaning liquid. In Patent Document 1, the absorbance is measured using ultraviolet light of a predetermined measurement wavelength determined for each component of oil contained in the cleaning liquid, and the calibration curve of the oil concentration and absorbance for each oil prepared in advance is prepared Based on the above, it is described to determine the concentration of the oil dissolved in the cleaning solution. The measurement wavelength for each oil is, for example, 259 nm for commercial press oil, 234 nm for commercial cutting oil, and 250 nm for commercial flux.

JP 09-061349 A

  In the oil concentration measurement apparatus and method described in Patent Document 1, since the measurement wavelength is different for each oil, it is necessary to detect light of a plurality of wavelengths corresponding to the measurement wavelengths. For that purpose, for example, a light source for irradiating the sample (hydrocarbon-based cleaning liquid) with light containing a plurality of wavelengths, a spectral element for dispersing the light passing through the sample for each wavelength, and a wavelength of the light dispersed by the spectral element A detector is used to detect each time. In such a configuration, it is necessary to use a dispersive element which is an expensive optical element, and it is also necessary to use an expensive one having a plurality of detection elements provided for each wavelength as a detector. Also, in order to obtain data almost simultaneously for each wavelength, expensive control equipment is required to process and store a large amount of data in a short time.

  The problem to be solved by the present invention is to provide an apparatus and method for measuring the concentration of oil in a cleaning liquid, which does not require the use of expensive spectroscopic elements, detection elements and control devices.

An oil concentration measuring device for cleaning fluid according to the present invention, which was made to solve the above-mentioned problems,
a) A light irradiator for irradiating a liquid to be measured with an irradiation light having a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm,
b) a transmitted light detection unit that measures the intensity of the transmitted light of the irradiated light transmitted through the liquid to be measured;
c) Based on the intensity of the transmitted light measured by the transmitted light detection unit, calculate the absorbance at the measurement wavelength of the liquid to be measured, and calculate the relationship between the value of the absorbance and the concentration of oil and the absorbance at the measurement wavelength And an oil concentration determination unit for determining the concentration of the oil in the liquid to be measured based on the calibration curve shown.

  As described above, many cleaning solutions such as hydrocarbon-based cleaning solutions and other glycol ether-based cleaning solutions, which are currently mainstream as cleaning solutions for industrial cleaning machines, have multiple (double, triple) bonds of carbon atoms. Consist of molecules that do not have A molecule that does not have such a multiple bond of carbon atoms absorbs light at wavelengths less than 280 nm, but hardly absorbs light at wavelengths greater than 280 nm. On the other hand, most of oil components such as cutting oil, press / punch oil, machine oil, grease, and flux which adhere to the workpiece to be cleaned and mix in the cleaning solution, contain molecules having multiple bonds of carbon atoms. Depending on the type, the wavelength at which the absorbance reaches a peak is distributed over a wide range depending on the type of molecule having multiple bonds of such carbon atoms, but the absorbance is 0 within the wavelength range of 280 to 300 nm regardless of the type of oil. It has no constant value. Furthermore, if the wavelength exceeds 300 nm, it will be difficult to detect oil having a low concentration of about 50 ppm.

  Therefore, in the present invention, the intensity of the transmitted light is measured at a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm, and the absorbance at the measurement wavelength is calculated based on the intensity, thereby measuring the liquid to be measured The concentration of the oil component can be determined based on a calibration curve showing the relationship between the oil component to be measured at the measurement wavelength and the absorbance while suppressing the influence of light absorption by the target cleaning solution).

  According to the oil concentration measurement apparatus of the present invention, since only a predetermined one wavelength is used as the measurement wavelength, it is not necessary to use a spectral element or a detection element for each wavelength. Further, since the amount of data to be processed simultaneously is smaller than in the case of using a plurality of wavelengths, it is not necessary to use an expensive control device. For example, without providing a dedicated control device for the oil concentration measuring device according to the present invention, control of the oil concentration measuring device can be performed using a control device (programmable logic controller) of an industrial washer. For these reasons, the oil concentration measuring apparatus according to the present invention can reduce the cost.

  The oil concentration measuring device according to the present invention can be suitably used to measure oil having a low concentration of 50 to 2000 ppm. Also, because it is suitable for measuring such low concentration oil components, the oil concentration measuring device according to the present invention is used for the above-mentioned steam cleaning and drying which needs the ability to detect oil components with low concentration of 50 ppm. It can be suitably used to measure the oil concentration in the post-regeneration washing solution. The target of measurement of the oil content by the oil concentration measuring device according to the present invention is not limited to the cleaning liquid after the regeneration, for example, by measuring the change in oil concentration in the cleaning tank during the cleaning of the work It can also be used for determining (when the time change of the oil concentration becomes equal to or less than a predetermined value is the end timing).

The oil concentration measuring device according to the present invention further comprises
A second light irradiator for irradiating the liquid to be measured with a second irradiation light having a second measurement wavelength which is a predetermined one wavelength between 320 and 340 nm;
A second transmitted light detection unit that measures the intensity of the second transmitted light through which the second irradiation light has transmitted the liquid to be measured;
Based on the intensity of the second transmitted light measured by the second transmitted light detection unit, the absorbance of the liquid to be measured at the second measurement wavelength is calculated, and the value of the absorbance and the oil content at the second measurement wavelength are calculated. A second oil concentration determination unit may be provided to determine the concentration of the oil in the liquid to be measured based on a calibration curve indicating the relationship between the concentration and the absorbance.

  Thus, in addition to the measurement using the irradiation light having the measurement wavelength which is a predetermined one wavelength between 280 and 300 nm, the second measurement wavelength having a predetermined one wavelength between 320 and 340 nm By determining the concentration of the oil in the liquid to be measured (washing liquid, washing liquid to be measured) using the irradiation light, it is possible to increase the measurement accuracy of the absorbance in the oil having a relatively long wavelength at which the absorbance peaks. Also in this case, it is not necessary to use light of a different wavelength for each type of oil, and it is sufficient to use light of two types of wavelengths, the measurement wavelength and the second measurement wavelength. Further, it is not necessary to use a spectral element, and it is not necessary to provide a large number of transmission light detection elements (a transmission light detection unit and a second transmission light detection unit). Furthermore, if the liquid to be measured is irradiated with the irradiation light and the second irradiation light at different times from each other, the detector for detecting the transmission light does not need to recognize the wavelength, so one common to both wavelengths It suffices to use a detector of A photodiode can be suitably used for such a detector.

The method for measuring the oil concentration in the cleaning liquid according to the present invention is
Irradiating a liquid to be measured with an irradiation light having a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm;
Measuring the intensity of light transmitted through the liquid to be measured by the irradiation light;
Based on the intensity of the transmitted light, the absorbance at the measurement wavelength of the liquid to be measured is calculated, and the value of the absorbance and the calibration curve showing the relationship between the oil content at the measurement wavelength and the absorbance are contained in the liquid to be measured It is characterized in that the concentration of oil is determined.

  According to the present invention, it is possible to obtain an inexpensive apparatus for measuring the concentration of oil in a cleaning liquid and a method without using expensive spectroscopic elements, detection elements and control devices.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows the industrial washer which has one Embodiment of the oil concentration measurement apparatus which concerns on this invention as a component. The figure which shows the measured value of the spectrum of the amount of transmitted light in four types of washing | cleaning liquids which consist of a molecule | numerator which does not have a multiple bond of a carbon atom. The functional block diagram which shows the function of the control part in the oil concentration measuring device of this embodiment. The graph which shows the result of having measured the transmitted light amount of the washing | cleaning liquid which contains four different types of oil components 1 each, respectively. The graph which shows the result of having calculated | required the light absorbency from the transmitted light amount shown in FIG. The graph which shows the calibration curve for every oil created based on the light absorbency shown in FIG. The graph which shows the result of having measured the concentration of the oil in the cleaning fluid with the oil concentration measuring device and method of this embodiment.

  An embodiment of the oil concentration measurement device and method according to the present invention will be described using FIGS. 1 to 7.

  FIG. 1 shows a schematic configuration of an industrial washer 1 having the oil concentration measuring device 10 of the present embodiment as a component. The industrial cleaning machine 1 is an apparatus for removing oil adhering to the work, and in addition to the oil concentration measuring apparatus 10, the first cleaning tank 11, the second cleaning tank 12, the steam cleaning / drying tank 13, and the temporary cleaning The storage tank 14, the distillation tank 15, the heat exchanger 16, the ejector 17, the post-regeneration washing liquid storage tank 18, and the sample cell washing liquid tank 19 are provided. Thick solid lines shown in FIG. 1 indicate liquid flow paths, thick broken lines indicate gas flow paths, and thin straight broken lines indicate paths of electrical signals.

(1) Overall Configuration and Operation of Industrial Cleaning Machine 1 Before describing the oil concentration measuring device 10 of the present embodiment, first, the overall configuration of the industrial cleaning machine 1 and the operation of cleaning a work will be described. The first cleaning tank 11 and the second cleaning tank 12 are provided with ultrasonic transducers for applying ultrasonic vibration to the cleaning liquid stored in the tank. Further, in order to facilitate the generation of cavitation due to ultrasonic waves, the inside of the first cleaning tank 11 and the second cleaning tank 12 is depressurized by a vacuum pump to degas the cleaning liquid. After the cleaning fluid is stored in the first cleaning tank 11 and the second cleaning tank 12, the workpiece is immersed in the cleaning fluid and ultrasonic vibration is applied to clean the workpiece. Here, since the content of the oil in the second cleaning tank 12 is smaller than the cleaning liquid in the first cleaning tank 11 for the reason described later, the work is first cleaned in the first cleaning tank 11. Then, by washing the work in the second washing tank 12, it is possible to minimize the reattachment of the oil in the washing liquid to the work.

  The steam cleaning and drying tank 13 is a tank for performing steam cleaning and drying on the work cleaned in the second cleaning tank 12. Steam used for steam cleaning and drying is supplied from the distillation tank 15 as described later. The vapor in the vapor cleaning / drying tank 13 and the cleaning liquid from which the substance remaining on the surface of the work has been removed are returned to the second cleaning tank 12. Further, the gas generated by the pressure reduction of the first cleaning tank 11 and the second cleaning tank 12 and the evaporation of the cleaning liquid is collected in the temporary storage tank 14.

  The distillation tank 15 is provided with a float valve 151, and when the liquid in the distillation tank 15 is reduced to a predetermined amount or less by distillation, the cleaning liquid is introduced from the temporary storage tank 14 into the distillation tank 15. The distillation tank 15 is heated by a heater (not shown) and depressurized by an ejector 17. Thereby, the cleaning solution evaporates leaving the oil as a liquid. A part of the generated steam is supplied to the steam cleaning / drying tank 13 as described above, and the remainder is condensed by the heat exchanger 16 and stored in the post-regeneration cleaning solution storage tank 18.

  The regenerated cleaning fluid from which the oil component has been removed by the distillation tank 15 flows from the regenerated cleaning fluid storage tank 18 into the second cleaning tank 12. The first cleaning tank 11 and the second cleaning tank 12 are connected by a second overflow pipe 122. The second overflow pipe 122 has a higher connection position with the second cleaning tank 12 than the connection position with the first cleaning tank 11, and the inflow of the cleaning liquid after regeneration causes the flow of the cleaning liquid in the second cleaning tank 12. When the liquid level becomes higher than the latter connection position, a part of the cleaning liquid in the second cleaning tank 12 naturally moves to the first cleaning tank 11. Therefore, the content of oil is smaller in the cleaning liquid in the second cleaning tank 12 than in the cleaning liquid in the first cleaning tank 11. In addition, the first cleaning tank 11 and the temporary storage tank 14 are connected by the first overflow pipe 112, and the inflow of the cleaning liquid from the second cleaning tank 12 causes the liquid level of the cleaning liquid in the first cleaning tank 11 to overflow. When it becomes higher than the connection position of the pipe 112, a part of the cleaning liquid in the first cleaning tank 11 naturally moves to the temporary storage tank 14 through the first overflow pipe 112.

  The first cleaning tank 11 has a first circulating filtration system 111 which takes the cleaning liquid out of the tank and returns it through the filter into the tank. A similar second circulation filtration system 121 is provided in the second washing tank 12 as well. These circulation filtration systems remove particles having a particle diameter of about 10 μm or more, and can not remove oil.

(2) Configuration of oil concentration measuring device 10 of the present embodiment Next, the configuration of the oil concentration measuring device 10 in the industrial washer 1 will be described in detail. The oil concentration measuring apparatus 10 includes a flow path 101 connected to the first cleaning tank 11, the second cleaning tank 12, and the post-regeneration cleaning liquid storage tank 18 as described later, and a liquid transfer pump 102 provided in the flow path 101. The sample cell 103 provided downstream of the liquid feed pump 102 in the flow path 101, the reference cell 1031 for reference measurement, the light irradiation unit 104, the transmitted light detection unit 105, and control of the entire apparatus And a control unit 106 that performs data processing described later.

  The inflow portion 1011 of the flow path 101 is supplied to the first cleaning tank 11 through the first relay pipe 113, to the second cleaning tank 12 through the second relay pipe 123, and to the post-regeneration cleaning liquid through the third relay pipe 183. Each storage tank 18 is connected. In addition, the first relay on-off valve 11V is provided in the first relay pipe 113, the second relay on-off valve 12V is provided in the second relay pipe 123, and the third relay on-off valve 18V is provided in the third relay pipe 183. ing.

  The outflow portion of the flow path 101 is connected to the temporary storage tank 14. Therefore, the cleaning liquid used for measurement in the oil concentration measuring device 10 passes through the temporary storage tank 14 and is distilled by the distillation tank 15 and is finally returned to the second cleaning tank 12 in a state where the oil is removed. The cleaning liquid used for the measurement may be directly returned from the outflow portion to the tank in which the cleaning liquid is stored.

  Each of the sample cell 103 and the reference cell 1031 is a cell made of quartz with little absorption of ultraviolet light. The sample cell 103 is connected to the flow path 101 at the time of normal measurement, and the reference cell 1031 is connected to measure the reference data. The reference cell 1031 contains a cleaning solution containing no oil, and the control unit 106 controls the control unit 106 to measure the reference data after interrupting the measurement of the oil concentration at predetermined time intervals.

  The light irradiator 104 irradiates the cleaning liquid (measurement target liquid) in the sample cell 103 with a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm in this embodiment, and the LED emits the measurement wavelength. It consists of In the present embodiment, the measurement wavelength is 290 nm.

  The reason why the measurement wavelength is one wavelength between 280 and 300 nm will be described with reference to FIG. FIG. 2 shows measured values of the spectrum of the amount of transmitted light in four types of cleaning solutions 1 to 4 consisting of molecules having no carbon atom multiple bond. Among the four types, cleaning solutions 1 to 3 are all saturated aliphatic hydrocarbon cleaning solutions, and cleaning solution 4 is a glycol ether cleaning solution. FIG. 2 also shows the spectrum of incident light. The amount of transmitted light of each of the four types of cleaning solutions is significantly smaller than the amount of incident light at a wavelength of less than 280 nm, and absorption of ultraviolet light by the cleaning solutions can be observed. On the other hand, when the wavelength is 280 nm or more, the difference between the transmitted light amount and the incident light is small, and the cleaning liquid hardly absorbs the ultraviolet light. Therefore, if the measurement is performed at a measurement wavelength of 280 nm, the concentration of the oil can be measured while suppressing the influence of the light absorption by the cleaning liquid. On the other hand, when the measurement wavelength exceeds 300 nm, as shown in FIG. 5 described later, the value of absorbance by oil at low concentration (100 ppm in the example shown in FIG. 5 and further 50 ppm) becomes too small. I can not Therefore, by setting one wavelength between 280 and 300 nm as the measurement wavelength, it is possible to measure the concentration of the oil even at a low concentration of about 50 ppm while suppressing the influence of the light absorption by the washing solution.

  The transmitted light detection unit 105 detects the intensity of the transmitted light having the measurement wavelength transmitted through the cleaning liquid in the sample cell 103, and includes a photodiode and a signal conversion unit. The photodiode detects the light of the measurement wavelength and outputs the intensity as an analog signal. The signal conversion unit converts an analog signal output from the photodiode into a digital signal.

  The control unit 106 has the function shown in the functional block diagram of FIG. A programmable logic controller or a personal computer can be used as the control unit 106, and the control device of the industrial washer may be applied as it is, or the control device of the oil concentration measuring device 10 may be provided. . The control unit 106 includes an oil concentration determination unit 1061, a reference data storage unit 1062, a calibration curve storage unit 1063, a condition input unit 1064, and a measurement control unit 1065. The oil concentration determination unit 1061 includes an absorbance calculation unit 1061A, a calibration curve selection unit 1061B, and a calibration curve application unit 1061C. The details of the oil concentration determination unit 1061 will be described later together with the operation of the oil concentration measurement device 10 of the present embodiment. In the reference data recording unit 1062, data (reference data) of the transmitted light amount at the measurement wavelength, which is measured in advance for the cleaning agent containing no oil component, is recorded. In the calibration curve recording unit 1063, the concentration and absorbance of the oil at the measurement wavelength are prepared based on the data measured in advance using a sample whose concentration of the oil is known for each oil that can be used for processing the work. A calibration curve showing the relationship of is recorded. When the components are similar among a plurality of processing oils having different manufacturers or model numbers, a common calibration curve may be used for the plurality of processing oils. The condition input unit 1064 is used by the measurer to input measurement conditions described later using an input device such as a touch panel. The measurement control unit 1065 controls the start and end of the irradiation of the light from the light source in the light irradiation unit 104, and the start and end of the process of each unit.

  The sample cell washing solution tank 19 is a tank in which a washing solution for washing the sample cell 103 (the same washing solution as a target of measurement of the oil concentration) is stored.

(3) Operation of oil concentration measuring device 10 of the present embodiment The operation of the oil concentration measuring device 10 of the present embodiment will be described. Here, the case where the concentration of oil is to be measured is the cleaning fluid after regeneration which is stored in the cleaning fluid storage tank 18 which is close to the concentration of oil in the steam used in the steam cleaning / drying tank 13.

  First, measurement is started by the measurer inputting a predetermined measurement condition in the condition input unit 1064 and then inputting a measurement start instruction. The measurement conditions input here are information (for example, maker and model number of processing oil) for specifying the processing oil adhering to the workpiece to be cleaned using the cleaning liquid to be measured.

  When the measurement is started, first, the relay valve corresponding to the cleaning tank or the storage tank in which the cleaning liquid to be measured is stored is opened. Here, the third relay on-off valve 18V provided in the third relay pipe 183 connected to the post-regeneration cleaning fluid storage tank 18 is opened. As a result, the post-regeneration cleaning fluid to be measured is introduced into the sample cell 103 through the channel 101. The first relay on-off valve 11V is opened if the cleaning liquid to be measured is the cleaning liquid in the first cleaning tank 11, and the second relay on-off valve 12V is opened if the cleaning liquid is in the second cleaning tank 12.

  The light irradiation unit 104 irradiates the cleaning liquid in the sample cell 103 with light of the measurement wavelength (290 nm). The transmitted light detection unit 105 measures the intensity I of the transmitted light amount transmitted through the cleaning liquid, converts the intensity I into a digital signal, and outputs the digital signal.

Next, the control unit 106 inputs a digital signal indicating the intensity I of the transmitted light output from the transmitted light detection unit 105, and also transmits from the reference data recording unit 1062 the transmitted light amount at the measurement wavelength of the cleaning liquid containing no oil. The reference data I ₀ which is The absorbance calculating unit 1061A of the control unit 106 obtains the absorbance A = log ₁₀ (I ₀ / I) of the washing liquid to be measured based on the intensity I of the transmitted light amount in the washing liquid to be measured and the reference data I ₀ .

  Subsequently, the calibration curve selection unit 1061 B of the control unit 106 selects a calibration curve corresponding to the identified processing oil based on the information for identifying the processing oil input by the condition input unit 1064. Get from Then, the calibration curve application unit 1061C applies the absorbance A of the cleaning fluid to be measured obtained by the absorbance calculation unit 1061A to the calibration curve selected by the calibration curve selection unit 1061B to obtain the concentration of the processing oil.

  Thereafter, the concentration of the processing oil is repeatedly determined by repeatedly performing irradiation of light by the light irradiation unit 104 and measurement of the intensity I of the transmitted light amount while continuously introducing the cleaning liquid after regeneration of the measurement object into the sample cell 103. Then, when the concentration of the processing oil exceeds a predetermined value, the residual liquid remaining in the distillation tank 15 is treated. The treatment of the residual liquid is carried out by separating the washing liquid and the processing oil in the residual liquid by boiling the residual liquid, and thereby discarding the processing oil remaining in the distillation tank 15.

  When the cleaning liquid to be measured is the cleaning liquid in the first cleaning tank 11 or the second cleaning tank 12, the concentration of the processing oil in the cleaning liquid is repeatedly determined by the same method as described above during the cleaning of the work, The measurement result can be used to determine the timing of the end of cleaning that the cleaning of the work is ended when the time change of the concentration becomes lower than a predetermined value.

(4) Examples of absorbance and calibration curve A plurality of samples prepared by mixing four kinds of oils selected as typical processing oils (Table 1) in the same cleaning liquid at different concentrations are prepared, and the amount of transmitted light for each oil and concentration Was measured to determine the absorbance. Here, in order to verify the appropriateness of setting the measurement wavelength to 290 nm, the amount of transmitted light was measured in the range of 260 to 400 nm without limiting the wavelength to 290 nm. Here, as the cleaning solution, “NS100” (a cleaning solution 1 of FIG. 2 manufactured by JX Energy Co., Ltd.) which is a cleaning solution of a saturated aliphatic hydrocarbon type having no carbon atom multiple bond was used. In addition, the concentration of each oil was 100 ppm, 500 ppm, 2000 ppm and 10000 ppm, respectively.

  The transmitted light amount obtained by the measurement is shown in FIG. 4 for each oil component contained in the cleaning liquid. Moreover, the result of having calculated | required the light absorbency based on the transmitted light quantity shown in FIG. 4 is shown in FIG. Both have different values depending on the concentration of the oil content in the wavelength range of 280 to 300 nm.

  Based on the thus obtained oil component at a wavelength of 290 nm and the absorbance for each concentration, a calibration curve showing the relationship between the absorbance and the concentration was created for each oil component. The prepared calibration curve is shown in FIG. In each oil, data with a concentration of 10000 ppm is not used because it deviates from the straight line in the calibration curve. As shown in FIG. 6, when the concentration is 2000 ppm or less, the calibration curve can be shown as a straight line. Therefore, measurement of the oil concentration is possible by the oil concentration measuring apparatus and method of the present embodiment at a concentration of at least 2000 ppm or less.

  In the industrial cleaning machine shown in FIG. 1, what is important for maintaining the quality of cleaning of the work is to measure and manage the concentration of the oil component of the post-regeneration cleaning solution which is regenerated by distillation in the distillation tank 15. In particular, since the cleaning solution after regeneration is used for steam cleaning which is the finishing cleaning of the work in the steam cleaning / drying tank 13 as it is, the steam generated in the distillation tank 15 continuously measures and controls the oil concentration of the industrial cleaning machine It is most important to do while driving. According to the present invention, it is possible to measure and manage the oil concentration during continuous operation of such an industrial washer.

  An experiment was conducted to measure the concentration of the oil in the washing solution after regeneration using the obtained calibration curve. Also in this experiment, five types of cutting were conducted using the above-mentioned NS100 or NS200 (manufactured by JX Energy Co., Ltd., cleaning liquid 2 in FIG. 2), and the oils to be added include those shown in Table 1 above. An oil and 5 types of press / punch oil were used. In this experiment, a sample having a known concentration (this concentration is referred to as "the original concentration") is prepared by weighing the washing solution and the oil component and mixing the two, and a comparison between the original concentration and the measured value is made. went.

  The experimental results are shown in the graph of FIG. In this graph, the original concentration is taken on the horizontal axis, and the measured value is taken on the vertical axis. Data points fall between the two dashed lines in the graph if the measurement falls within ± 10% of the original concentration. Moreover, in FIG. 7, the data were put on one graph for all the samples. As shown in this graph, all the measured values obtained this time are approximately within ± 10% of the original concentration. An accuracy on the order of ± 10% is sufficient for use in industrial cleaners.

(5) Modifications In the oil concentration measuring device 10 according to the present embodiment, the light irradiator 104 irradiates the cleaning liquid with light having a measurement wavelength of 280 to 300 nm (290 nm in the above example) to the cleaning liquid. The cleaning liquid may be irradiated with a second measurement wavelength which is a predetermined one wavelength between 340 nm. It is desirable that such light of two different wavelengths be generated using two light sources that emit monochromatic light and have different wavelengths of the monochromatic light. In this case, as long as the transmitted light detection unit 105 can measure the intensities of both the light of the measurement wavelength and the light of the second measurement wavelength, only one of the two wavelengths is commonly detected. I hope there is. Alternatively, different transmitted light detection units may be used for each wavelength. Also at the second measurement wavelength, as in the case of the measurement wavelength (290 nm), it is possible to create a calibration curve showing the relationship between the absorbance and the concentration for each oil based on the data of absorbance in FIG.

  For example, the calibration curve shown in FIG. 6 (d) is slightly larger than the calibration curves of (a) to (c) because the difference between the absorbance and the calibration curve is slightly larger. The accuracy can be increased by determining the concentration of the oil component respectively.

DESCRIPTION OF SYMBOLS 1 ... Industrial cleaning machine 10 ... Oil concentration measurement apparatus 101 ... Flow path 1011 ... Inflow part 102 ... Liquid feeding pump 103 ... Sample cell 1031 ... Reference cell 104 ... Light irradiation part 105 ... Transmission light detection part 106 ... Control part 1061 ... Oil concentration determination unit 1061A ... Absorbance calculation unit 1061 B ... Calibration curve selection unit 1061 C ... Calibration curve application unit 1062 ... Reference data recording unit 1063 ... Calibration curve recording unit 1064 ... Condition input unit 1065 ... Measurement control unit 11 ... First cleaning tank 111 ... first circulation filtration system 112 ... first overflow pipe 113 ... first relay pipe 11 V ... first relay on-off valve 12 ... second washing tank 121 ... second circulation filtration system 122 ... second overflow pipe 123 ... second relay pipe 12V ... 2nd relay on-off valve 13 ... steam cleaning and drying tank 14 ... temporary storage tank 15 ... distillation tank 151 ... float valve 16 ... heat exchanger 17 Ejector 18 ... playback after the cleaning liquid storage tank 183 ... third relay pipe 18V ... third relay off valve 19 ... sample cell washing solution tank

Claims (5)

a) A light irradiator for irradiating a liquid to be measured with an irradiation light having a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm,
b) a transmitted light detection unit that measures the intensity of the transmitted light of the irradiated light transmitted through the liquid to be measured;
c) Based on the intensity of the transmitted light measured by the transmitted light detection unit, calculate the absorbance at the measurement wavelength of the liquid to be measured, and calculate the relationship between the value of the absorbance and the concentration of oil and the absorbance at the measurement wavelength And an oil concentration determination unit for determining the concentration of the oil in the liquid to be measured based on the calibration curve shown. further,
A second light irradiator for irradiating the liquid to be measured with a second irradiation light having a second measurement wavelength which is a predetermined one wavelength between 320 and 340 nm;
A second transmitted light detection unit that measures the intensity of the second transmitted light through which the second irradiation light has transmitted the liquid to be measured;
Based on the intensity of the second transmitted light measured by the second transmitted light detection unit, the absorbance of the liquid to be measured at the second measurement wavelength is calculated, and the value of the absorbance and the oil content at the second measurement wavelength are calculated. And a second oil concentration determination unit for determining the concentration of the oil in the liquid to be measured based on a calibration curve indicating the relationship between the concentration and the absorbance. . Irradiating a liquid to be measured with an irradiation light having a measurement wavelength which is a predetermined one wavelength between 280 and 300 nm;
Measuring the intensity of light transmitted through the liquid to be measured by the irradiation light;
Based on the intensity of the transmitted light, the absorbance at the measurement wavelength of the liquid to be measured is calculated, and the value of the absorbance and the calibration curve showing the relationship between the oil content at the measurement wavelength and the absorbance are contained in the liquid to be measured A method of measuring the concentration of an oil component in a cleaning liquid, comprising determining the concentration of the oil component.   The method according to claim 3, wherein the liquid to be measured comprises a molecule having no carbon atom multiple bond. further,
The measurement target liquid is irradiated with a second irradiation light having a second measurement wavelength which is a predetermined one wavelength between 320 and 340 nm;
Measuring the intensity of the second transmitted light through which the second irradiation light has passed through the liquid to be measured;
Based on the intensity of the second transmitted light, the absorbance at the second measurement wavelength of the liquid to be measured is calculated, and the value of the absorbance and a calibration curve showing the relationship between the oil content and the absorbance at the second measurement wavelength The method according to claim 3 or 4, wherein the concentration of oil in the liquid to be measured is determined.

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