JPH01197634A - Liquid refractometer and liquid concentration meter using same - Google Patents

Abstract

PURPOSE:To measure a refractive index on an off-line basis at all times by putting an image fiber which photodetects and guides measurement light to a detection part in a sensor probe. CONSTITUTION:The sensor probe 9 contains a light guide 2 which guides the measurement light, a sensor part 6 which refracts the measurement light guided by the light guide 2 and detects the refractive index of the sample liquid, and the image fiber 8 which photodetects and guides the measurement light projected from the sensor part 6. Then the sensor probe 9 is dipped directly in the sample liquid first. Then the measurement light which is guided 8 is detected by a detection part 7 as a light signal, which is converted into an electrode signal by various photodetecting elements. The data which is converted into the electric signal is processed 16 by using a relational expression to find the refractive index of the sample liquid. Thus, only the sensor probe 9 is dipped directly in the sample liquid without sampling the sample liquid, so the refractive index of the liquid is measured on an on-line basis at all times.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a fluid refractometer for liquids, gases, etc., and a fluid density meter using the same. This allows the refractive index and density of a sample fluid to be directly measured online at all times without sampling.

[Prior art and its problems] Conventionally, as a deviation device for measuring the refractive index of fluids such as liquids, in addition to the Atsube method, which measures the refraction angle of light by a prism, and the minimum deviation method, the focal length device that changes depending on the refractive index of the sample has been used. There are many known refractometers based on the law of refraction of light, such as the Duc de Charne method, which measures .

However, in all of the liquid refractometers described above, the sensor section that detects the refractive index of the sample is directly connected to other equipment, making it difficult to separate only the sensor section. Therefore, since the sample liquid must be sampled each time during measurement, it has been impossible to constantly measure the refractive index of the liquid online.

In addition, when determining the density directly from the sample liquid, sampling is even more difficult, and even if we take advantage of the fact that the density of the liquid is given by the refractive index, the refractive index of the liquid can always be measured online as described above. Constant online measurement of density was also not possible.

This invention was made to solve the above problems,
The object of the present invention is to provide a fluid refractometer that can measure the refractive index of a fluid online at all times by directly immersing only a sensor probe into a sample fluid, and a fluid density meter using the fluid refractometer.

[Means for Solving the Problems] The present invention includes a light guide that guides measurement light from a light source, and avoids refraction of the measurement light guided by this light guide, and connects the basic prism and the auxiliary prism to the point where fluid is introduced. The solution is that a sensor section that faces each other with a gap therebetween, and an image fiber that receives measurement light emitted from the sensor section and guides it to the detection section are housed in a sensor probe.

Further, the fluid density meter of the present invention includes a light guide that guides measurement light from a light source, a light guide that refracts the measurement light guided by the light guide, and a basic prism and an auxiliary prism that are connected to an air gap for introducing fluid. A sensor section facing each other via the sensor section and an image fiber that receives the measurement light emitted from the sensor section and guides it to the detection section are housed in the sensor probe, and the density is determined from the measured refractive index of the sample fluid. The solution is to connect the computing unit that performs calculations to the detection unit.

[Function] Inside the sensor probe, there is a light guide that guides the measurement light, a sensor section that refracts the measurement light guided by the light guide inside and detects the refractive index of the sample fluid, and this sensor. Since the image fiber that receives and guides the measurement light emitted from the sensor is housed, the sensor probe can be directly immersed in the sample fluid without sampling the sample fluid during measurement, so it can be used online at all times. The refractive index of a fluid can be measured.

Furthermore, since the calculation section is connected to the detection section, the density of the fluid can be calculated from the measured refractive index of the fluid, and the density of the fluid can be measured online at all times.

[Example] The present invention will be described in detail below.

FIG. 1 shows an embodiment in which the present invention is used to measure the refractive index of a liquid. This liquid refractometer utilizes the fact that the emission angle of the measurement light emitted from the sensor section changes by interposing a sample liquid between the basic prism and the auxiliary prism of the sensor section housed in the sensor probe. The refractive index of the sample liquid is determined using the Ara-Be method, which is a method for measuring the refractive index of transparent materials based on the law of refraction of light.

This liquid refractometer has a light source l at one end and a lens 3a at the other end.
a light guide 2 to which a light guide 2 is attached, and a basic prism 4 that avoids refracting the measurement light guided by this light guide 2.
and an auxiliary prism 5, a sensor section 6, and an image fiber 8 having a detection section 7 and a calculation section 16 attached to one end and a lens 3b attached to the other end, housed in a sensor probe 9. be.

The sensor probe 9 includes one end of a light guide 2 that guides measurement light from a light source 1, and a sensor section 6 that includes a basic prism 4 and an auxiliary prism 5 that refracts the measurement light guided by the light guide 2. The lens 3b that condenses the measurement light emitted from the sensor section 6 is attached to a tube body that houses one end of the image fiber 8. In order to protect it from stress and the like, it is housed within a tubular protective member made of stainless steel or the like.

The light guide 2 uses a low-loss optical fiber, and the image fiber 8 uses a bundle of a large number of core/clad optical fibers suitable for image transmission and is fused together.

Furthermore, the light guide 2 and image fiber 8 housed in the sensor probe 9 are protection tubes formed by extending the protection member of the sensor probe 9! 0, a light source I is connected to the other end of the light guide 2, and an image fiber 8
A detection unit 7 is connected to the other end.

As the light source l, a sodium lamp, laser, LED, etc. with good monochromaticity is suitably used. When using white light, it is preferable to separate the light into monochromatic light using a monochromatic filter, and use the measurement light as is from light source l to light guide 2
The wave is guided to the sensor probe 9 by the sensor section 6.
Guided within.

The sensor unit 6 uses the principle of Atsube's refractometer to measure the refraction angle of light by a prism, and the basic prism 4
It consists of two prisms: and an auxiliary prism 5, and detects the brightness/darkness boundary that occurs within the visual field by refraction of the measurement light that passes through these prisms.

The basic prism 4 and the auxiliary prism 5 are placed facing each other with a certain gap for introducing the sample liquid, and this gap is selected depending on the refractive index of the sample liquid, but is usually 0 mm or 1 mm. It is maintained at a certain level.

In order to introduce the sample liquid into this gap, the auxiliary prism 5
There is a hinge on the outside of the sensor probe 9 where the sensor probe 9 is housed. An auxiliary prism cell 13 to which an auxiliary prism 5 and a solenoid 12 are fixed by a hinge 11 is attached to the tip of the sensor probe 9 so as to be openable and closable. The auxiliary prism cell 13 is opened and closed by moving the drive pin 14 of the solenoid I2 in the longitudinal direction of the solenoid 12.

In addition, 1. The inner wall of the sensor probe 9 from which the measurement light transmitted through the basic prism 4 is emitted is arranged such that the measurement light emitted from the basic prism 4 is focused on the lens 3b attached to one end of the image fiber 8. , a mirror 15 is installed. The measurement light emitted from the basic prism 4 is a mirror! After being reflected by the light beam 5, the light is focused by the lens 3b and guided to the detection section 7 connected to the other end of the image fiber 8.

The detection unit 7 has a built-in light receiving element such as a CCD array, and after receiving and detecting the projected image of the measurement light separated by the sensor unit 1 as an optical signal, converts it into an electrical signal and converts it into an electrical signal, which is then converted into an electrical signal. The refractive index of the sample liquid is calculated using the formula.

In order to measure the refractive index of a liquid such as an extremely low temperature liquefied gas using a liquid refractometer having such a configuration, the sensor probe 9 is first immersed in the liquefied gas. Next, the driving bottle 14 of the solenoid 12 housed in the auxiliary prism cell 13 is moved forward to open the auxiliary prism cell 13, and the sample liquid is introduced into the gap between the basic prism 4 and the auxiliary prism 5 of the sensor section 6. After that, the drive bottle 14 is moved back and the auxiliary prism cell 13 is closed to form a liquid phase of the sample liquid in the sensor section 6 with a desired thickness.

Next, the lamp la is caused to emit light and the wavelength is selected by the monochromatic filter lb, and then the measurement light is guided by the light guide 2. The measurement light guided within the light guide 2 is guided into the auxiliary prism 5 and the basic prism 4 which face each other via the sample liquid phase.

This measurement light is separated into bright and dark boundaries within the field of view, and is emitted from the base prism 4, with an exit angle corresponding to the critical angle between the base prism 4 and the measurement light as a boundary. The image of the bright/dark boundary within this field of view is reflected by the mirror 15, then condensed by the lens 3b attached to the image fiber 8, and guided within the image fiber 8 to the detection section 7.

The guided measurement light is detected as an optical signal by the detection unit 7, and then converted into an electrical signal by various light receiving elements. The refractive index n of the sample liquid can be determined by calculating the data converted into an electric signal using the following equation (1).

n=5inψ−rm'−5in″β+CO8ψsinβ
-(1) Here, n: refractive index of the sample liquid ψ: apex angle of the basic prism m: refractive index of the basic prism Next, an example in which the present invention is used to measure the density of a liquid will be described.

In this liquid density meter, a calculation section 16 connected to the detection section 7 calculates the density from the refractive index of the sample liquid measured by the above-mentioned liquid refractometer. This calculation section 16
is installed outside the sensor probe of the liquid refractometer mentioned above, and constantly receives the refractive index of the sample liquid measured by the liquid refractometer online, and calculates the density of the sample liquid from the refractive index data. .

In a liquid density meter having such a configuration, the refractive index of the sample liquid is first measured by the detection unit 7 of the liquid refractometer described above, and then the refractive index data of the sample liquid is transmitted to the calculation unit connected to the detection unit 7. 16, and here the density ρ of the sample liquid can be determined using the following equation (2).

p = (n”-1)/r(n”+2)-(2
) Here, ρ: density of the sample liquid, n: refractive index of the sample liquid, r: greater than or equal to the relative refractive index difference of the sample liquid. The same thing can be done when measuring the refractive index and density of.

[Effects of the Invention] As explained above, the fluid refractometer of the present invention includes a light guide that guides measurement light from a light source, a light guide that refracts the measurement light guided by the light guide, and a basic prism and an auxiliary prism. The sensor probe houses a sensor section in which a prism faces the prism through a gap for introducing fluid, and an image fiber that receives the measurement light emitted from the sensor section and guides it to the detection section. Therefore, it is possible to directly immerse only the sensor probe into the sample fluid.

Therefore, without sampling the fluid during measurement,
Since the sensor section can be directly immersed in the sample fluid, it is possible to measure the refractive index of cryogenic fluids such as liquefied gases, which cannot normally be sampled, online at all times.

Furthermore, in the fluid density meter of the present invention, the calculation unit that calculates the density from the measured refractive index of the sample fluid is connected to the detection unit of the fluid refractometer, so the density can be calculated online at all times. Therefore, it is useful for the production and quality control of liquefied gas and the like.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of a liquid refractometer of the present invention and a liquid density meter using the same. I...Light source, 2...Light guide, 4...Basic prism, 5...Auxiliary prism, 6...Sensor section, 7...Detection section,
8... Image fiber, 9... Sensor probe, 16... Arithmetic unit.

Claims (2)

[Claims] (1) A light guide that guides the measurement light from the light source, and a light guide that refracts the measurement light guided by the light guide.
A sensor section consisting of a basic prism and an auxiliary prism facing each other with a gap for fluid introduction, and an image fiber that receives the measurement light emitted from the sensor section and guides it to the detection section are housed in the sensor probe. A fluid refractometer characterized by: (2) A light guide that guides the measurement light from the light source, and a light guide that refracts the measurement light guided by the light guide.
A sensor section consisting of a basic prism and an auxiliary prism facing each other with a gap for fluid introduction, and an image fiber that receives the measurement light emitted from the sensor section and guides it to the detection section are housed in the sensor probe. A fluid density meter characterized in that a calculation unit for calculating density from the measured refractive index of the sample fluid is connected to the detection unit.