JP2001124695A - Method for detecting alcohol/water mixing ratio and device for detecting alcohol/water mixing ratio - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for detecting alcohol/water mixing ratio hardly influenced by the measuring environment and capable of doing precise measurement. SOLUTION: This device comprises a light source 3 for emitting a light in infrared area and a detector 4 for detecting the light in infrared area from the light source 3. An optical path LP between the light source 3 and the detector 4 is passed to an alcohol/water mixture TS, the infrared absorption quantity by the alcohol or water contained in the alcohol/water mixture TS is detected, and the mixing ratio is determined on the basis of the detection result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting a mixture ratio of alcohol / water used for, for example, a fuel cell.

[0002]

2. Description of the Related Art At present, a polymer electrolyte fuel cell of a low temperature operation type, which is expected as a new energy source for electric vehicles and the like, is being developed. As a method of supplying fuel to such a fuel cell, pure hydrogen, methanol (including methanol reformed gas), hydrogen by partial oxidation of gasoline, and the like are considered.

In terms of environment and efficiency, gasoline <methanol <pure hydrogen is superior, and on the other hand, in terms of facility (infrastructure), pure hydrogen <methanol <gasoline. The use of methanol is considered to be the mainstream for mobile objects.

In a steam reforming reaction for producing hydrogen using methanol, 75% of H ₂ and 25% of CO ₂ should theoretically be generated (Equation 1). Trace amounts of carbon monoxide (CO) and the like are included.

CH ₃ OH + H ₂ O → 3H ₂ + CO ₂ (Equation 1) This CO has a poisoning effect on the catalyst of the electrode part and lowers the battery performance.
Need to be converted to CO ₂ .

CO + H ₂ O → CO ₂ + H ₂ (Equation 2) For this reason, it is necessary that methanol and water introduced into the reformer have a composition of a predetermined ratio in which water is more than 1: 1 in a molar ratio. It is very important to control the mixing ratio of methanol and water.

Although not related to fuel cells, sake,
Detection of the mixing ratio of ethanol / water in the production process and inspection of alcohol-containing beverages such as shochu is also an important measurement.

[0008]

In the prior art, in measuring the mixing ratio of methanol and water, there is one that detects the specific gravity of the mixed solution.

For example, in the fuel cell disclosed in Japanese Patent Application Laid-Open No. Hei 8-91804, a sensor is disposed in a storage tank to detect the specific gravity and the temperature of the mixed liquid, and to measure the specific gravity according to the temperature. The correction is used to determine the mixture ratio.

However, the above-mentioned measurement based on the difference in specific gravity between methanol and water requires direct contact between the mixture and the sensor or the detection device. It becomes difficult to maintain accuracy for measurement in the state.

In addition, even if the measurement environment and conditions are good, it is difficult to further increase the measurement accuracy of the specific gravity measurement in the case of a sensor configuration having a mechanically movable portion such as a floating body.

The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a mixture ratio of alcohol / water which is hardly affected by a measurement environment and enables high-precision measurement. An object of the present invention is to provide a detection method and device.

In this description, alcohol means
Although it is assumed that ethanol, methanol and the like are used, methanol will be described below as one of suitable examples.

[0014]

In order to achieve the above object, in the method for detecting a mixture ratio of alcohol / water according to the present invention, light in the infrared region is transmitted through a mixed solution of alcohol / water and transmitted. The detection method of detecting the light in the infrared region through a filter means having a transmission window in a wavelength band in which infrared absorption by alcohol or water is performed, the mixing ratio is known in advance, and the mixing ratio is different. The method is applied to a plurality of mixed liquids of alcohol / water, the correlation between the mixing ratio and the detection result is determined, and the detection method is applied to the alcohol / water to be measured.
The mixing ratio of the alcohol / water mixture to be measured is determined based on the correlation from the detection result obtained by applying the mixture to the water.

In the apparatus for detecting a mixture ratio of alcohol / water, a light source for generating light in an infrared region including a wavelength band in which infrared absorption by alcohol or water is generated, and an infrared light from the light source. A detecting means for detecting the light, and a filter means disposed in front of the detecting means, having a transmission window in a wavelength band where infrared absorption by alcohol or water is performed in light in the infrared region, An optical path of light in the infrared region between the light source and the detection means is provided so as to pass through a mixed solution of alcohol / water to be measured.

With this configuration, light in the infrared region passes through the alcohol / water mixture to be measured, and filters the infrared absorption that changes in accordance with the alcohol / water mixture ratio. Means and detection means.

In addition, the apparatus includes a container into which a mixed liquid of alcohol / water to be measured is supplied. The light source, the detecting means, and the filter means are arranged outside the container, and the optical path of the light is transmitted to the container. It is also preferable to pass the inside of the container through the provided transmission window.

The measurement can be performed without contacting the mixture itself with the apparatus itself, and the operation stability and the maintenance property are improved.

The correlation between the mixing ratio and the detection result obtained based on the detection results obtained for a plurality of mixed solutions of alcohol / water having different mixing ratios is known in advance. A storage unit for storing information, and a detection result for the alcohol / water mixture to be measured is calculated based on the correlation information held in the storage unit, and the alcohol / water mixture for the measurement is calculated. And a calculation output means for obtaining and outputting the mixing ratio of

By providing the storage means and the arithmetic output means in this way, error correction of the detection result due to individual differences of the apparatus is performed, and the detection accuracy is improved.

A second window is disposed in the optical path between the light source and the detecting means and has a transmission window in a wavelength band excluding a wavelength band in which infrared absorption by alcohol or water is performed in light in an infrared region. Filter means, and second detection means for detecting light in the infrared region which has passed through the second filter means, wherein the arithmetic output means detects two detections of the detection means and the second detection means It is also preferable to use the differential output of the means as the detection result for the alcohol / water mixture to be measured.

By the second filter means and the second detection means, a reference output irrespective of the concentration state of the alcohol / water mixture can be obtained, and a subtle change in the detection output of the alcohol or water is determined as the reference output. , It is possible to perform highly accurate detection that does not depend on the measurement environment.

It is also preferable to provide a reflector for bending the optical path.

The degree of freedom in the structure and arrangement of the apparatus can be increased, and the arrangement can be made smaller and less affected by vibrations.

The wavelength band in which infrared absorption by alcohol or water is performed in light in the infrared region is defined as a wavelength band in which infrared absorption of alcohol is performed, from 2.2 μm to 2.4 μm.
μm, 3.2 μm to 3.6 μm, 6.4 μm to 7.3 μm
m, 8.5 μm to 10.5 μm, and 1.3 μm to 1.6 as a wavelength band in which infrared absorption of water is performed.
μm, 1.7 μm to 2.2 μm, 2.6 μm to 3.4 μm
m, any one of 5.5 μm to 6.5 μm is also preferable.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an apparatus for detecting a mixture ratio of alcohol / water and a method for detecting a mixture ratio of alcohol / water will be described below with reference to the drawings. Here, the alcohol includes methanol, ethanol, and the like.

In the alcohol / water mixture ratio detection device 1 (hereinafter, referred to as a mixture ratio detection device) shown in FIG. 1, an alcohol / water mixture TS (hereinafter, referred to as a mixture) to be measured is used. A light source 3 for generating light in the infrared region and a detector 4 as detection means for detecting light in the infrared region are arranged on both sides of the tube 2 that transmits infrared light as a container supplied therein. I have. LP is an optical path between the light source 3 and the detector 4.

In this embodiment, the cylinder 2 is made of a material that transmits infrared light in the present embodiment. However, the cylinder 2 may be provided with a transmission window at a portion where the optical path LP passes.

The detector 4 is provided with infrared light receiving elements 6a and 6b for receiving two infrared lights, and the infrared light receiving element 6a transmits light in a wavelength band in which infrared absorption by alcohol or water is performed. Filter 5a as filter means having a window
The infrared light receiving element 6b is provided with a filter 5b as a second filter means having a transmission window in a band other than a wavelength band in which infrared absorption by alcohol or water is performed.

Each of the filters 5a and 5b is disposed in the optical path LP between the light source 3 and the infrared light receiving elements 6a and 6b of the detector 4.

The wavelength band in which infrared absorption by alcohol is performed is 2.2 μm to 2.4 μm (2.3 μm band),
3.2 μm to 3.6 μm (3.5 μm band), 6.4 μm
７7.3 μm (6.9 μm band), 8.5 μm〜10.5
μm (9.5 μm band).

The wavelength band in which infrared absorption is performed by water is 1.3 μm to 1.6 μm (1.4 μm band), 1.7 μm.
μm to 2.2 μm (1.9 μm band), 2.6 μm to 3.
4 μm (3.0 μm band), 5.5 μm to 6.5 μm
(6.0 μm band).

In particular, the absorption band of water, 3.0 (2.6 to 2.6)
3.4) The μm band has a wide band with large absorption intensity,
There is no problem even if the filter has a transmission window of 2.5 to 7 μm (the influence of the absorption of alcohol in the 3.5 μm band is small).

The water absorption band of 1.4 μm (1.
Since the absorption intensity in the band of 3 μm to 1.6 μm) is large, there is no problem as a filter having a transmission window of visible light region to 7 μm (the influence of alcohol absorption in the 2.3 μm band is also small).

As the light source 3, since a wavelength band in which infrared absorption by alcohol or water is performed appears in a relatively wide range, any light source that emits infrared light (infrared light) of at least up to 11 μm may be used. Lamps and the like using tungsten or the like for the filament are small and easy to use.

As the infrared light receiving elements 6a and 6b of the detector 4, there are a quantum type photoconductive sensor and a photovoltaic type sensor, a thermal type thermopile bolometer, a pyroelectric sensor, and the like. is there. Among them, the thermal type is more suitable.

Only the infrared light that has passed through the filters 5a and 5b enters the infrared light receiving elements 6a and 6b, respectively.

The alcohol / water mixture ratio detecting device 1 having such a configuration, when utilizing only the detection result of the infrared light receiving element 6a, specifies the ratio according to the mixture ratio of alcohol and water in the mixture TS. (For example, when a filter having a transmission window of 2.5 to 7 μm in which infrared absorption by water is performed is selected) according to the amount of infrared light absorbed in the wavelength band, By changing the amount of external light and changing the detection output of the detector 6a, the mixing ratio of alcohol / water can be measured.

In order to more accurately measure the mixing ratio of alcohol / water, the mixing ratio is known in advance, and a plurality of mixed solutions TS1, T of alcohol / water having different mixing ratios are known.
S2,..., And the correlation between the mixture ratio and the detection result is obtained. From the detection result for the mixture TS to be measured, the mixture ratio of the mixture TS to be measured based on the correlation is obtained. Is calculated and obtained.

FIG. 9 shows that 1.5 mol, 1.75 mol and 2.0 mol of water are added to 1 mol of alcohol,
It is a graph which shows the light-absorbing amount with respect to each mixed liquid from which the mixing ratio was made different, and the light-absorbing amount changes with the mixing ratio being different.

FIG. 10 is a graph showing the amount of light absorbed when alcohol and water are used alone.

The calculation based on the correlation means that the calculation is performed by using a function for associating the mixture ratio with the detection output, or the detection output is divided into minute regions, and the corresponding mixture ratio in the region is calculated. It is possible to store the information and make it correspond to a matrix.

FIG. 2 is a block diagram showing a circuit configuration for performing arithmetic processing on the detection result from the detector 4 and outputting the mixture ratio.

The signal from the detector 4 is input to the arithmetic output means 7 together with data relating to the correlation between the detected mixture and the mixture ratio obtained from the mixed liquid whose mixing ratio is known in advance, stored in the storage means 8. Is output as a mixing ratio.

As described above, by providing the storage means 8 and the calculation output means 7 and testing the measurement results of the respective devices, errors in the detection results due to individual differences of the devices are corrected, and the detection accuracy is further improved. It is planned.

Further, in the configuration of FIG. 1, a set of second filters 5 is further provided as a reference in a case where higher accuracy is required or a case where the filter is used in a wide range of temperatures.
b and an infrared light receiving element 6b.

The transmission window of the second filter 5b must be set outside the absorption wavelength band of alcohol or water and the infrared absorption wavelength band included in the target environment.
1.3 μm band or 3.7 to 5.4 μm band, for example, 1.
Those having a transmission window in a wavelength band of 1 μm, 4.0 μm, or 4.6 μm can be used.

Then, as shown in FIG. 3 which is a block diagram showing the circuit configuration of the detected value processing means, the outputs of two light receiving elements, an infrared light receiving element 6a and a second infrared light receiving element 6b, are output. Process as differential output.

The operation circuit K1 takes a difference signal between the mixed liquid output signal S1 (output value related to the mixing ratio) and the reference output signal S2, thereby detecting a subtle signal change of the mixed liquid output signal S1.

This utilizes the fact that the reference output signal S2 does not depend on the mixing ratio, and amplifies this operation output to obtain a corrected mixed liquid output signal S4.

In the temperature correction, since the mixed liquid output signal S1 and the reference output signal S2 relatively change, it is possible to detect a more accurate change in concentration by calculating the difference. Therefore, the temperature correction only needs to take into account the variation due to the slight difference in the temperature dependence of each output signal, and the temperature output signal S3 is added to the difference signal between the mixed liquid output signal S1 and the reference output signal S2. Has been corrected.

By providing the reference output in this way, a more accurate mixed liquid output signal (corrected mixed liquid output signal S4) can be obtained over a wide range of temperatures.

By using the mixed liquid output signal S4 as the output signal of the detector 4 (see FIG. 2), a more accurate mixing ratio can be obtained.

Since infrared light is used, there is no need to bring the detection device itself into direct contact with the mixture, and the measurement can be performed even when the alcohol / water mixture TS to be measured is vibrating or flowing. Accuracy can be maintained, and moving parts can be eliminated as sensors,
Operation reliability can be improved.

Further, since the measurement target area is set by the optical path LP, the measurement accuracy can be further improved by using a plurality of optical paths LP or bending the optical path LP by a reflector as described later and passing the path plural times. It is also possible.

FIGS. 4 and 5 show an embodiment in which a reflection plate 9 for reflecting infrared rays well is provided and the arrangement of the light source 3 and the detector 4 is changed. The arrangement of the mixing ratio detection devices 1B and 1C is shown. ing.

In FIG. 4, the light source 3 and the detector 4 are arranged on the same side, and the optical path LP passes through the cylinder 2 twice by the reflection plate 9.

FIG. 5 shows that the cylinder 2 is supported horizontally,
One end is closed, and two reflection plates 9 are provided.
By closing one end, alcohol /
Since a decrease in responsiveness due to stagnation of the water mixture TS may be considered, a configuration may be adopted in which both ends of the cylinder 2 are communicated in the same manner as in FIGS. It is also good.

As described above, the light source 3 and the detector 4 may be opposed to each other, or may be arranged on the same side and the reflecting plate 9 such as a mirror for efficiently reflecting infrared rays is arranged at the opposed portion. In addition, the arrangement (horizontal, vertical, etc.) and form of the mixed liquid passage can be arbitrarily determined according to the situation.

FIGS. 6, 7 and 8 show a case where a mixed solution TS of alcohol / water to be measured is held in the container 12, and the light source 3 and the detector 4 are directly attached to the container 12. is there.

In this embodiment as well, the light source 3 and the detector 4 may be opposed to each other, or may be arranged on the same side and a reflecting plate 9 such as a mirror for efficiently reflecting infrared rays is arranged at the opposed portion. Good. In addition, the arrangement of the passage for the mixture (horizontal,
Vertical etc.) can be arbitrarily arranged according to the situation.

Although not shown in the figure, a transmission window may be provided in the container 12, and the light source 3 and the detector 4 may be provided outside the container 12. Also in this case, the light source 3 and the detector 4 may be made to correspond to each other, or a configuration in which a reflecting plate 9 such as a mirror which efficiently reflects infrared rays is arranged on the opposite side and is arranged on the opposite side.

[0063]

According to the present invention described above, the mixing ratio of the alcohol / water mixture can be measured with high accuracy.

An alcohol / water mixture T to be measured
Even when S is oscillating or in a flowing state, it is possible to maintain the measurement accuracy, eliminate a movable part, and improve the operation reliability.

Further, by providing the storage means and the arithmetic output means, the error correction of the detection result due to the individual difference of the apparatus is performed, and the detection accuracy is improved.

Further, when the second filter means serving as a reference and the second detection means are used together, the mixing ratio can be measured with higher accuracy over a wide range of temperatures.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of a mixture ratio detection device according to an embodiment.

FIG. 2 is a block diagram of a circuit configuration for performing arithmetic processing.

FIG. 3 is a block diagram of a circuit configuration of a detection value processing unit for obtaining an operation output.

FIG. 4 is a diagram schematically illustrating a configuration example of a mixing ratio detection device.

FIG. 5 is a diagram schematically illustrating a configuration example of a mixing ratio detection device.

FIG. 6 is a diagram schematically illustrating a configuration example of a mixing ratio detection device.

FIG. 7 is a diagram schematically illustrating a configuration example of a mixing ratio detection device.

FIG. 8 is a diagram schematically illustrating a configuration example of a mixing ratio detection device.

FIG. 9 is a graph showing the amount of light absorbed for each mixed solution having a different mixing ratio.

FIG. 10 is a graph showing the amount of light absorbed when alcohol and water are used alone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixing ratio detector 2 Tube 3 Light source 4 Detector 5a, 5b Filter 6 Infrared light receiving element 7 Calculation output means 8 Storage means LP optical path TS Mixed liquid S1 Mixed liquid output signal S2 Reference output signal S3 Temperature output signal S4 Corrected Mixed liquid output signal K1 operation circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G059 AA01 AA05 BB04 BB15 CC09 CC15 EE01 FF08 GG10 HH01 HH06 JJ02 JJ13 KK01 KK03 MM10 NN02

Claims (7)

[Claims] 1. A filter means having a window for transmitting infrared light through an alcohol / water mixture and transmitting the transmitted infrared light in a wavelength band in which infrared light is absorbed by alcohol or water. Is applied to a plurality of mixed solutions of alcohol / water having different mixing ratios in advance, and a correlation between the mixing ratio and the detection result is obtained. From the detection results obtained by applying the method to the alcohol / water mixture to be measured, the mixing ratio of the alcohol / water mixture to be measured is determined based on the correlation. A method for detecting the mixing ratio of alcohol / water. 2. A light source for generating light in an infrared region including a wavelength band in which infrared absorption by alcohol or water occurs, a detecting means for detecting light in the infrared region from the light source, It has a transmission window in a wavelength band where infrared absorption by alcohol or water is performed in the light, and comprises a filter means disposed in front of the detection means, of light in an infrared region between the light source and the detection means. An alcohol / water mixture ratio detecting device, wherein an optical path is provided so as to pass through an alcohol / water mixture to be measured. 3. A container, into which a mixed solution of alcohol / water to be measured is supplied, wherein the light source, the detection unit, and the filter unit are arranged outside the container, and the optical path of the light is set in the container. The alcohol / water mixture ratio detecting device according to claim 2, wherein the mixture is passed through the inside of the container through a transmission window provided. 4. A correlation between a mixture ratio and a detection result obtained based on detection results obtained for a plurality of mixed solutions of alcohol / water having different mixture ratios, wherein the mixture ratio is known in advance. A storage unit for holding information, and a detection result for the alcohol / water mixture to be measured is calculated based on the information on the correlation held in the storage unit, and the alcohol / water mixture for the measurement is calculated. 4. An apparatus for detecting a mixture ratio of alcohol / water according to claim 2 or 3, further comprising: an arithmetic output means for calculating and outputting a mixture ratio of the alcohol / water. 5. A light source, which is disposed in the middle of an optical path between the light source and the detecting means and has a window for transmitting light in an infrared region in a wavelength band excluding a wavelength band in which infrared absorption by alcohol or water is performed. 2 filter means, and second detection means for detecting light in the infrared region that has passed through the second filter means, wherein the arithmetic output means comprises two of the detection means and the second detection means. The alcohol / water mixture ratio detecting device according to claim 4, wherein the differential output of the two detecting means is used as a detection result for the alcohol / water mixture to be measured. 6. The apparatus according to claim 2, further comprising a reflector that bends the optical path. 7. A wavelength band in which infrared absorption by alcohol or water is performed in light in an infrared region is a wavelength band in a range of 2.2 μm to 2.2 μm in which infrared absorption of alcohol is performed.
4 μm, 3.2 μm to 3.6 μm, 6.4 μm to 7.3
μm, 8.5 μm to 10.5 μm, and 1.3 μm to 1.3 μm as a wavelength band in which infrared absorption of water is performed.
6 μm, 1.7 μm to 2.2 μm, 2.6 μm to 3.4
The alcohol / water mixture ratio detection device according to any one of claims 2 to 6, wherein the mixing ratio is one of μm, 5.5 μm to 6.5 μm.