JP2006145498A - Oil content concentration measurement method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil content measurement method and oil content measuring apparatus for reducing not only ozone depletion coefficients but also global warming coefficients, while equally maintaining at least the oil content extraction capability of the case using chlorotrifluoroethylene dimer. <P>SOLUTION: The oil content concentration measuring apparatus for analyzing a solvent for extracting oil content, in which the oil content is extracted by adding the solvent for extracting the oil content to liquid containing the oil content by an infrared light absorption method comprises a cell 11 that uses hydrochlorofluorocarbon as the solvent for extracting the oil content and to which hydrochlorofluorocarbon whose oil content has been extracted is supplied; an infrared light source 16 arranged at one end side; and optical filters 19, 20 and infrared photodetectors 17, 18 arranged at the other end side of the cell 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oil concentration measuring method and an oil concentration measuring apparatus for measuring the concentration of oil contained in natural water, waste water from a factory, a sewage treatment plant, or soil.

  As a method for measuring oil contained in natural water or waste water, an infrared absorption method (hereinafter referred to as NDIR method) using absorption of C—H groups at a wavelength of about 3.4 μm is widely used. . FIG. 8 schematically shows the entire apparatus used for oil concentration measurement by the infrared absorption method. In this figure, reference numeral 1 denotes an extraction tank, and a vibrator 2 driven by a commercial power source is provided in the inside thereof. A stirring member 5 including a stirring rod 3 connected to the head and a stirring blade plate 4 attached to the stirring rod 3 is provided, and an inlet 6 for a sample and an extraction solvent is provided above the stirring member 5. A flow path 8 is connected to the lower part of the extraction tank 1 via an electromagnetic valve 7, and a non-dispersive infrared analyzer (NDIR) is incorporated downstream of a filter 9 provided in the flow path 8. An oil concentration meter 10 is provided.

In the oil concentration measuring apparatus configured as described above, each sample (oil-containing liquid) and the oil extraction solvent are accommodated in the extraction tank 1 and stirred by the stirring member 5 to obtain a sample. The oil contained therein is extracted into an oil extraction solvent, and the oil extraction solvent containing the oil is supplied to the oil concentration meter 10 through the filter 9. As described above, the oil concentration can be obtained by performing the analysis by the NDIR method.
JP-A-7-270310

  Thus, when extracting the oil component from the sample water into the oil extraction solvent and quantifying the concentration of the oil component extracted into the oil extraction solvent using the NDIR method, absorption of C—H groups at a wavelength of about 3.4 μm is obtained. Since it is necessary to carry out the measurement using carbon tetrachloride, carbon tetrachloride containing no C—H group has generally been used as an oil component extraction solvent. However, along with the use of carbon tetrachloride and production regulations, the oil concentration was quantified using chlorotrifluoroethylene dimer as an alternative. Chlorotrifluoroethylene dimer is a type of chlorofluorocarbon. This chlorotrifluoroethylene dimer has the merit that the ozone depletion coefficient is smaller and the environmental load is smaller than carbon tetrachloride. However, in recent years, it has been pointed out that chlorotrifluoroethylene dimer also has a high ozone depletion coefficient and a large environmental load.

Further, in the conventional chlorotrifluoroethylene dimer solvent as the oil extraction solvent, as can be seen from the absorption spectrum 100 of the chlorotrifluoroethylene dimer solvent (hereinafter simply referred to as solvent) shown in FIG. Since there is almost no absorption around a certain 3.4 μm (around 2941 cm ⁻¹ ), it is possible to measure without being disturbed by the solvent. In FIG. 7, reference numerals 101, 102, and 103 indicate examples of absorption spectra used when the oil concentration meter 10 is used to quantify the oil concentration. In this example, these absorption spectra 101, 102, and 103 indicate absorption spectra at different concentrations in the same oil type (same measurement target component). And the density | concentration of an oil component is high in order of the absorption spectrum 101,102,103.
However, the oil to be measured has a wide absorption in the range. Therefore, when quantifying the concentration of oil by the non-dispersive NDIR method, the optical filter used ideally includes the vicinity of 3.4 μm, which is the measurement range of oil, and is absorbed into the solvent itself and extracted into the solvent. Those having spectral characteristics that pass through the ideal optical filter range (between the end P and the end Q) 104 shown by the double-headed arrow in FIG. 6A until the absorption of the measurement target component overlaps. Necessary. However, in consideration of individual differences of the optical filter itself, actually, an optical filter in a range 104 ′ (between the end P ′ and the end Q ′) narrower than the ideal optical filter range 104 is used. Become. However, since the individual differences of the optical filters themselves and the oil content to be measured are different as described above, the absorption at both ends P ′ and Q ′ of the range through which the actually used optical filter transmits may vary from side to side. is there. That is, in FIG. 7, the actual optical filter range 104 ′ may be a range indicated by 105, for example. This causes an instruction difference for each device and deterioration of linearity in the same device. Therefore, the present inventors have various ways how the oil extraction ability can be maintained equivalent to the case of using chlorotrifluoroethylene dimer and the ozone depletion coefficient can be made smaller than that of using chlorotrifluoroethylene dimer. We studied earnestly with these solvents. As a result, the present inventors have found that it is most preferable to use hydrochlorofluorocarbon as a solvent, and have provided the following inventions.

That is, an object of the present invention is to provide an oil concentration measuring method and an oil concentration capable of reducing not only the ozone depletion coefficient but also the global warming coefficient while maintaining at least the oil extraction ability equivalent to the case of using chlorotrifluoroethylene dimer. It is to provide a measuring device.

  The oil concentration measurement method of the present invention is an oil concentration obtained by adding an oil extraction solvent to a liquid containing oil and extracting the oil by analyzing the oil extraction solvent by infrared absorption. In the measurement method, hydrochlorofluorocarbon is used as the oil extraction solvent (claim 1).

  Further, according to another aspect of the present invention, in the oil concentration measuring apparatus for analyzing the oil extraction solvent obtained by adding the oil extraction solvent to the oil-containing liquid and extracting the oil component by infrared absorption method, the oil extraction solvent A cell supplied with hydrochlorofluorocarbon from which oil has been extracted, an infrared light source disposed at one end thereof, an optical filter and an infrared light detector disposed at the other end of the cell An oil concentration measuring device is provided (claim 4).

  In the invention according to claim 1 of the present application, for example, in measurement of oil concentration in wastewater and environmental water, hydrochlorofluorocarbon is used as a solvent for extracting oil from sample water, and infrared absorption (NDIR method) is applied to obtain oil content. The concentration is measured. And in invention concerning Claim 1 of this application, the following effects are produced by using hydrochlorofluorocarbon as a solvent for oil content extraction.

(1) The oil extraction capability is equal to or higher than when chlorotrifluoroethylene dimer is used.
(2) Both global warming potential and ozone depletion potential can be reduced compared to chlorotrifluoroethylene dimer.

  Further, in the invention according to claim 4 of the present application, hydrochlorofluorocarbon is used as a solvent for oil extraction, a cell to which hydrochlorofluorocarbon from which oil has been extracted is supplied, an infrared light source disposed on one end thereof, and a cell An optical filter and an infrared light detector arranged on the other end side of That is, a hydrochlorofluorocarbon solvent (hereinafter simply referred to as a solvent) has only one C—H bond such as dichloropentafluoropropane (Claim 6), and the other bond is a bond between halogen and carbon. For this reason, there is strong absorption on the high wave number side from the oil content measurement range. That is, this solvent has a strong infrared absorption band in the wave number region close to the high wave number side of the absorption band peculiar to the C—H group in the oil. Therefore, an area until the absorption of the solvent itself and the absorption of the measurement target component extracted into the solvent overlap, that is, an ideal optical filter range 204 as indicated by a double arrow in FIG. It can be made narrower than the ideal optical filter range 104 in FIG. Therefore, even if the same optical filter as shown in FIG. 6A having the actual optical filter range 104 ′ is used, the wave number region indicated by X in FIG. For this reason, the wave number region indicated by X acts as an optical filter that limits the infrared transmission range, thereby causing an influence that has been a problem in the past, that is, the optical filter itself. It is possible to eliminate the influence caused by the individual difference of the oil and the oil content to be measured. From this, it is possible to improve the instruction difference for each device and the linearity of the same device.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited thereby.

  1 to 4 show an embodiment of the present invention. 1 to 4, the same reference numerals as those shown in FIGS. 6 and 7 are the same or equivalent.

  The oil concentration measurement method of the present invention is greatly different from the conventional NDIR method in that the analysis is performed using a hydrochlorofluorocarbon such as dichloropentafluoropropane as the oil extraction solvent. Dichloropentafluoropropane (hereinafter referred to as HCFC-225) is 3,3-dichloro-1,1,1,2,2-pentafluoropropane (3,3-Dichloro-1,1,1,2,2- pentafluoropropane) [HCFC-225ca] and / or 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC) -225cb] as a component.

  As shown in Table 1 below, HCFC-225 has the same oil content extraction ability as chlorotrifluoroethylene dimer. That is, by using HCFC-225, the oil extraction capability became equal to or higher than that when chlorotrifluoroethylene dimer was used.

  Further, as shown in Table 2 below, HCFC-225 has a smaller global warming potential and ozone destruction coefficient than chlorotrifluoroethylene dimer.

In HCFC-225, as can be seen from the absorption spectrum 200 of HCFC-225 shown in FIG. 3, HCFC-225 is close to the high wavenumber side of the absorption band peculiar to the C—H group (near 2941 cm ⁻¹ ; near 3.4 μm). There is an infrared absorption band in the wave number range (2970-3090 cm ⁻¹ ), and there is little infrared absorption in the absorption band peculiar to the C—H group. By utilizing the infrared transmission characteristic unique to HCFC-225, an optical filter (infrared transmission filter) to be used, for example, an optical filter having an optical filter range 104 ′ as shown in FIGS. 6B and 6A is used. The selectivity on the high wavenumber side can be relaxed. That is, as described above, since the solvent itself has strong absorption in the wave number region indicated by X in FIG. 6B, in the wave number region indicated by X, the optical as if the solvent limits the infrared transmission range. It acts like a filter. In other words, in the present invention, the infrared transmission characteristic unique to the oil extraction solvent is treated in the same way as the spectral characteristic of the optical filter (infrared transmission filter) and processed, so that the high frequency side of the optical filter (infrared transmission filter) is increased. The selectable range can be relaxed. As a result, infrared absorption peculiar to the C—H group can be detected with high accuracy, and linearity is improved. In FIG. 4, ◯ indicates a measured value when HCFC-225 is used, and in FIG. 5, Δ indicates a measured value when chlorotrifluoroethylene dimer is used. 4 and 5, it can be seen that the error is smaller in the indicated value when HCFC-225 is used than in the indicated value when chlorotrifluoroethylene dimer is used.

  Hereinafter, the procedure of the oil concentration measuring method of the present invention will be described. First, as shown in FIG. 1, a sample which is a liquid containing oil and HCFC-225 as an oil extraction solvent are weighed so as to have a predetermined amount (step S1).

  The sample and HCFC-225 are stirred in the stirring tank 1 to perform oil extraction processing. By this process, the oil content in the sample moves to HCFC-225 and is extracted (step S2). In addition, as the stirring tank 1, it is preferable to use what was disclosed by Unexamined-Japanese-Patent No. 7-308506, for example.

  After the extraction, a solvent layer containing oil and a water layer are separated, and only the solvent layer is supplied to the analysis unit (step S3).

In the analysis unit, the absorption around 2800 to 3100 cm ⁻¹ is measured by the NDIR method to obtain the oil concentration (step S4).

  FIG. 2 shows the structure of an oil concentration meter 10 used in the oil concentration measuring apparatus of the present invention. In this figure, 11 is a cell to which a solvent layer containing the oil (hereinafter referred to as sample S) is supplied. It is made of a material having excellent corrosion resistance such as stainless steel, and both ends thereof are sealed with cell windows 12 and 13 made of an infrared transmitting material (for example, quartz glass), and a sample S is supplied and discharged. A sample inlet 14 and a sample outlet 15 are provided.

  Reference numeral 16 denotes an infrared light source which is provided on one cell window 12 side of the cell 11 and irradiates the cell 11 with infrared light.

  Reference numerals 17 and 18 are provided in parallel to each other on the other cell window 13 side of the cell 11, and a measurement detector and a comparison detector as infrared detectors for receiving infrared light passing through the cell 11. Both detectors 17 and 18 are, for example, pyroelectric infrared detectors.

Reference numerals 19 and 20 denote interference filters (bandpass filters) provided on the front surfaces (light-receiving surfaces) of the measurement detector 17 and the comparison detector 20, respectively. The interference filter 19 on the measurement detector 17 side has a wave number region. For example, only infrared light of 2800 to 3100 cm ⁻¹ is allowed to pass through, but infrared light in other wavenumber regions is not allowed to pass therethrough. The interference filter 20 on the comparison detector 20 side is also configured to pass only infrared light having a wave number region of, for example, 2800 to 3100 cm ⁻¹ , while not transmitting infrared light in other wave number regions. Is.

  21 is an optical chopper provided between the detector-side cell window 13 and the interference filters 19 and 20, which is driven by a motor 22 to intermittently pass infrared light passing through the cell 11 at a predetermined cycle. .

  23 and 24 are preamplifiers for appropriately processing the outputs of the measurement detector 17 and the comparison detector 18, respectively, 25 is an amplifier for amplifying and A / D converting the outputs of the preamplifiers 23 and 24, and 26 is a micro amplifier. It is an arithmetic unit composed of a computer or the like.

In the oil concentration meter 10 based on the NDIR method described above, the measurement detector 17 outputs an oil absorption waveband output I based on the oil contained in the sample S. Further, the comparison detector 18 outputs a comparison output I _{0 that} is not absorbed by oil. Then, the calculation unit 26 calculates log (I ₀ / I) and multiplies it by a predetermined constant to obtain the oil concentration.

  It was found that the measurement result with the oil concentration meter 10 of the present invention was in good agreement with the result using the chlorotrifluoroethylene dimer.

  In addition, as an oil concentration meter used by this invention, what was disclosed by Unexamined-Japanese-Patent No. 8-33459, for example can also be used. In this case, as the interference filter provided on the front surface (light receiving surface side) of the measurement detector, the same interference filter 19 as used in the above embodiment is provided, and the intensity of the infrared light source is set to a certain ratio (for example, 8%). ), By providing a so-called ND filter having a characteristic of uniformly decreasing over the entire wave number region on the front surface (light-receiving surface side) of the comparison detector, the oil concentration is quantified in the same manner as in the above embodiment. be able to. In addition, as another oil concentration meter used in the present invention, a measurement cell and a comparison cell in which air is sealed are used, and the same interference filters 19 and 20 used in the above embodiment are used as a measurement detector. Even when the detectors provided on the respective front surfaces (light receiving surface side) of the comparison detector are used, the concentration of the oil component can be quantified as in the above embodiment.

  In the present invention, the weight of a trace amount of oil that is negligible compared to the oil extraction solvent is measured by the weight method or the microbalance method. That is, HCFC-225 has a lower boiling point than carbon tetrachloride and chlorotrifluoroethylene dimer. The boiling point of HCFC-225 is 54 ° C., and the boiling point of chlorotrifluoroethylene dimer is 134 ° C. Utilizing this physical property, after extracting a very small amount of oil into HCFC-225, volatilizing HCFC-225, the oil concentration in HCFC-225 can be increased, resulting in high sensitivity. The oil concentration can be quantified.

  The weight method used for the measurement of the weight can be achieved by applying an n-hexane extraction method based on, for example, Japanese Industrial Standard JIS K0102. Further, as the microbalance method used for the weight measurement, for example, as disclosed in Japanese Patent Laid-Open No. 6-194290, weight measurement using a crystal resonator can be exemplified.

  Here, for example, an extraction solvent containing a low concentration of oil of 1 ppm or less is prepared, and the concentration of the oil is doubled by volatilizing the extraction solvent in the air for about 1 hour until the amount of the extraction solvent becomes half. Can be. For example, in the case of HCFC-225, it takes only a short time of about 1 hour to evaporate the extraction solvent so that 10 ml of the extraction solvent becomes 5 ml. On the other hand, in order to do the same with chlorotrifluoroethylene dimer, it is necessary to prepare a heater and the volatilization time becomes longer.

  By measuring the extraction solvent thus concentrated by the NDIR method, it is possible to measure the oil concentration with high sensitivity.

  In addition, the oil content in the soil can be quantified by extracting it with the solvent.

It is a flowchart which shows roughly the measurement procedure in the oil concentration measuring method of this invention. It is a figure which shows an example of a structure of the oil concentration meter used by this invention. It is a figure which shows the absorption spectrum of the solvent for oil extraction used in this invention, and the absorption spectrum used when quantifying the concentration of oil. It is a standard solution density | concentration vs indicator value characteristic view obtained by this invention. It is a standard solution density | concentration / indication value characteristic view of a conventional example. (A) is a figure for demonstrating the operation principle and problem of a prior art example. (B) is a figure for demonstrating the principle of operation of this invention. It is a figure which shows the absorption spectrum of the solvent for oil extraction used in the prior art example, and the absorption spectrum used when quantifying the concentration of the oil. It is a figure which shows roughly the structure of a general oil concentration measuring apparatus.

Explanation of symbols

11 cell 16 infrared light source 17, 18 infrared light detector 19, 20 optical filter 200 absorption spectrum of solvent for oil extraction

Claims (6)

  In the oil concentration measurement method, wherein the oil concentration solvent is obtained by analyzing the oil extraction solvent obtained by adding the oil extraction solvent to the oil-containing liquid and extracting the oil content by infrared absorption method, the oil extraction solvent Hydrochlorofluorocarbon is used as the oil content concentration measuring method.   The oil concentration measuring method according to claim 1, wherein the weight of a very small amount of oil contained in the oil extraction solvent is measured by a weight method or a microbalance method.   The oil concentration measuring method according to claim 1 or 2, wherein dichloropentafluoropropane is used as the hydrochlorofluorocarbon.   In the oil concentration measuring device that analyzes the oil extraction solvent by adding the oil extraction solvent to the oil-containing liquid by infrared absorption, the oil is extracted using hydrochlorofluorocarbon as the oil extraction solvent. An oil component comprising: a cell supplied with the hydrochlorofluorocarbon, an infrared light source disposed on one end thereof, an optical filter and an infrared light detector disposed on the other end of the cell. Concentration measuring device.   5. The oil concentration measuring apparatus according to claim 4, wherein the optical filter is an interference filter configured to transmit infrared light in a predetermined wave number region and not transmit infrared light in other wave number regions.   The oil concentration measuring apparatus according to claim 4 or 5, wherein dichloropentafluoropropane is used as the hydrochlorofluorocarbon.

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