JPH06174639A - Refractometer - Google Patents

Abstract

PURPOSE:To furnish a refractometer enabling suitable attainment of an object such as explosion-protection by improving construction of a cell part. CONSTITUTION:This refractometer has a cell inside of which a sample constituted of a fluid is made to flow through, a light source which applies a light to the sample flowing through this cell and a detecting part which detects the light refracted by the sample. The cell is constructed of lighttransmitting bodies 24 and 25 disposed at positions at which the light passes and formed of a light-transmitting material such as glass, and of frame bodies 41, 42 and 43 formed of stainless steel or the like which is a material having a larger pressure-resisting strength than the material of the light-transmitting bodies 24 and 25. The cell is assembled by putting in a buffer member such as an O ring between the frame bodies 41, 42 and 43 and the light-transmitting bodies 24 and 25 and by fastening the frame bodies (41 and 42, 41 and 43) mutually by screws or by other means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractometer used for sample analysis and detection of impurities in liquid.

[0002]

2. Description of the Related Art Needless to say, a refractometer measures the refractive index of a material, but the measurement of the refractive index of an optical material is also widely applied to sample analysis and the like. A refractometer in sample analysis detects and analyzes changes and differences in the refractive index of materials, and detects differences in the refractive index of the reference mobile phase in order to offset changes in the measurement environment such as the light source. The differential refractometer used is widely used.

FIG. 4 is a schematic explanatory view of a differential refractometer as an example of a conventional refractometer. There are two types of differential refractometers, a polarization type that measures the deflection angle of light and a Fresnel type that uses Fresnel's law. The polarization type is shown in FIG. The refractometer shown in FIG.
A cell 2 which circulates a fluid sample at a position where it is irradiated with light from the light source 1, a mirror 5 arranged behind the cell 2, a detector 3 which receives and detects light refracted by the sample, and the like. It is mainly composed of. The detection unit 3 includes a light receiving unit 31 that receives the light refracted by the cell, an amplifier 32 that amplifies the signal photoelectrically converted by the light receiving unit 31, a recorder 33 that records the analysis result by the amplified signal, and the like. ing.

FIG. 5 is a diagram showing details of the cell 2 in the refractometer of FIG. As shown in FIGS. 4 and 5, the cell 2 in the conventional refractometer is a prismatic column having a square cross-section formed entirely of a translucent material such as glass. The inner partition wall 23 arranged diagonally divides the interior into two spaces having an equilateral cross section, one of which serves as the reference mobile phase flow section 21 and the other of which serves as the sample flow section 22. In FIGS. 4 and 5, the light source 1
The light from is incident on the front surface (side surface on the light source 1 side) of the cell 2 at a right angle. The incident light first passes through the inside 21 of the mobile phase flow section for reference, then passes through the internal partition wall 23 while being slightly refracted, and then passes through the inside of the sample flow section 22. Then, the light exits from the rear surface (side surface on the mirror 5 side), is reflected by the mirror 5, and is incident on the cell 2 again. Then, conversely, the light passes through the sample flow section 22, the internal partition wall 23, and the reference mobile phase flow section 21 in this order, and then exits from the front surface and reaches the detection section 3.

In the above light path, if the medium in the reference mobile phase flow section 21 and the medium in the sample flow section 22 have the same refractive index, as shown in FIG. In addition, the light paths of the light that enters the front surface of the cell 2 and the light that exits the front surface of the cell 2 coincide with each other. However, if the refractive indexes of the two are slightly different from each other, as shown in FIG. 5B, the optical paths of the incident light and the emitted light do not coincide with each other, and a deflection angle φ occurs. On the other hand, the light flux that reaches the detection unit 3 through the cell 2 is configured to have a predetermined rectangular shape by a plurality of slits, lenses, etc. (not shown), and when the deflection angle φ as described above occurs, the received light is received. As a result, the irradiation pattern for irradiating the light receiving surface of the portion 31 is slightly displaced. This shift amount can be easily detected by using a two-division photoelectric conversion element in the light receiving unit 31 and monitoring the light reception amount of each element, and by detecting such a shift amount, the deflection angle φ can be determined. Then, the difference in refractive index is detected.

[0006]

The refractometer as described above may be installed not only in chemical analysis such as chromatography but also in a plant or the like. That is, the above-mentioned refractometer is attached to monitor the material transport pipe in the plant to monitor the operating state of the plant. In the case of such an application, a large amount of flammable material is often present in the surroundings, and it is necessary to provide a structure for preventing danger in accordance with a predetermined safety standard. In such a case, the instrument is usually covered with an explosion-proof box, and the inside is pressurized with an air supply blower that draws in air from a safe place to prevent dangerous flammable gas from reaching the inside of the instrument. The design is done.

According to a study conducted by the inventor, in the case of the conventional refractometer as described above, such a design for explosion-proof is generally difficult because the withstand voltage of the cell portion is low. It turned out to be Also, according to a study by the inventor,
It has been found that in the conventional cell configuration, the pressure resistance becomes a problem even when the sample is circulated at a high pressure of 10 kilograms or more per square centimeter. The invention of the present application has been made in order to solve such a new problem, and is to improve the configuration of the cell portion to provide a refractometer capable of suitably achieving an object such as explosion-proof. .

[0008]

In order to achieve the above-mentioned object, the refractometer according to claim 1 of the present application is such that a sample made of a fluid is circulated inside and the external pressure becomes equal to or higher than atmospheric pressure. The cell has a cell having an internal pressure of 10 kilograms or more per square centimeter, a light source for irradiating the sample flowing in the cell with light, and a detection unit for detecting refracted light refracted by the sample irradiated with light. Is composed of a translucent body arranged at a position where light passes through, and a frame body made of a material having a higher pressure resistance than the translucent body.

[0009]

EXAMPLES Examples of the present invention will be described below. Figure 1
FIG. 3 is a front sectional view showing an outline of a cell in an embodiment of the refractometer of the present invention. 2 is a plan sectional view of the cell of FIG. Unlike the conventional cell 2 shown in FIG. 5, the cell 2 shown in FIG. 1 and FIG. That is, if the stability of the light source, the detection unit and the like is high, the reference mobile phase flow unit can be eliminated. The cell 2 shown in FIGS. 1 and 2 has two light-transmitting bodies 24 and 25.
And three frame bodies 41, 4 for holding the translucent bodies 24, 25.
2 and 43.

First, the translucent bodies 24 and 25 are specifically disk-shaped glass plates, and the exit-side translucent body 25 has a larger diameter than the incident-side translucent body 24. There is. Then, as can be seen from the plane cross section of FIG.
4 is arranged at a right angle to the optical axis,
Are arranged at an angle of 45 degrees with respect to the optical axis. Specifically, the three frame bodies 41, 42, 43 are for fixing the two light-transmitting bodies 24, 25 to the main frame body 41 in which the sample is circulated, and the main frame body 41. Entrance side frame 42
And the emission side frame body 43. These three frames 41, 4
Both 2 and 43 are made of metal such as stainless steel.

First, as can be seen from the plane cross section of FIG. 2, the main frame 41 has a substantially prismatic shape as a whole, and has a shape in which one end is cut obliquely (specifically, 45 degrees). They are arranged in a state where the height direction is horizontal, that is, they are laid down. Also, as can be seen from FIGS. 1 and 2,
The main frame body 41 has a through hole 40 having a circular cross section that penetrates along the horizontal direction, and has a structure in which both ends of this through hole 40 are closed by two light transmitting bodies 24 and 25. There is. Then, as shown in FIG. 1, a sample inflow hole for allowing the sample to flow into the through hole 40 is formed in the bottom portion of the main frame 41, and the inflow side ferrule 44 is fixed to the sample inflow hole. It is fixed. The inflow side ferrule 44 is connected to a sample supply pipe connected to a sample container (not shown).

On the other hand, as shown in FIG. 2, the main frame 41
A sample outflow hole for allowing the sample to flow out from the inside of the through hole 4 is formed on the side portion of, and the outflow side ferrule 45 is fixed so as to be fixed to this sample outflow hole. The outflow-side ferrule 45 is connected to a discharge pipe connected to a waste liquid tank (not shown). Therefore, the inside of the main frame 41 is
The sample flows in and collects by the inflow side ferrule 44,
The ferrule 45 on the outflow side allows the ferrule to flow out little by little. The use of such ferrules 44 and 45 is for stabilizing the flow rate and amount of the sample.

Further, the incident side light-transmitting body 24 is attached to the end portion of the main frame 41 on the side not cut. That is, the end surface of the main frame 41 on the incident side is in a posture perpendicular to the optical axis, and the end surface has a size larger than the diameter of the through hole 40 and adapted to the diameter of the incident side light-transmitting body 24. A circular recess is formed in the center of the surface. Then, the incident-side translucent body 24
Are fitted in this recess. The depth of the recess is
The thickness is larger than the thickness of the incident-side translucent body 24. Therefore, even when the incident-side translucent body 24 is fitted, a step is formed between the end surface of the main frame body 41 and the incident-side translucent body 24 for incidence. The side translucent body 24 is in a state of being retracted inward.

The incident-side light-transmitting body 24 fitted in this way
Are fixed by the incident side frame 42. The incident side frame 24 is formed of a ring-shaped collar portion 241 and a cylindrical protrusion portion 242 protruding from the inner peripheral edge of the collar portion 241. The outer diameter of the protrusion 242 has a size that matches the diameter of the recess of the main frame 41, and the tip of the protrusion 242 is applied to the incident-side light-transmitting body 24 fitted in the recess. In this way, it is pushed into the concave portion of the main frame body 41. In this state, the collar portion 241 abuts on the end surface of the main frame body 41, and the collar portion 241 and the main frame body 41 are screwed together, so that the incident-side translucent body 24 is fixed. An unillustrated cushioning material such as an O-ring is sandwiched between a portion where the main frame 41 and the incident-side translucent body 24 abut and a portion where the incident-side frame 24 and the incident-side translucent body 24 abut. It is arranged. This is to prevent the translucent body 24 from being damaged by the pressure applied to the translucent body 24 made of glass because the frames 41 and 42 are made of metal. It also has the meaning of preventing leakage of the sample flowing inside the main frame 41. Note that, due to this cushioning material, the flange portion 241 and the end surface of the main frame body 41 may not be in complete contact with each other but may be slightly separated.

On the other hand, on the obliquely cut end surface of the main frame body 41, the emitting side light transmitting body 25 is provided by the emitting side frame body 43.
Is fixed. The light-transmitting-side translucent body 25 has a rectangular plate shape as a whole, and a large opening for light passage is provided in the center. The shape and size of this opening will be described in detail. First, the opening is entirely circular. Then, from one surface of the emission side frame body 43, the emission side translucent body 2
Up to a depth approximately equal to the thickness of 5, the inner diameter is adapted to the diameter of the light-transmitting side light-transmitting body 25. Then, at a position slightly deeper than this, there is a part in which a small ridge portion 431 is circumferentially formed and the inner diameter is slightly smaller.
In other words, when the light-transmitting-side transmissive body 25 is dropped into the opening from the one surface, the ridge portion 431 is exposed to the light-transmitting-side translucent body 25.
It is in a condition to receive.

The emission side frame body 43 having the emission side frame body 43 dropped in the opening portion in this manner is fixed to the main frame body 41. That is, as shown in FIG. 1 and FIG.
The one surface of the main frame body 41 is brought into contact with the diagonally cut end surface of the main frame body 41, and both are screwed. In this case as well, in order to prevent damage to the light-transmitting side light-transmitting body 25, leakage of the sample, and the like, the portion where the main frame 41 and the light-transmitting side light-transmitting body 25 contact each other and the light-transmitting side light-transmitting body 25 and the light-transmitting side frame body 43. A cushioning member (not shown) such as an O-ring is also sandwiched between the portions where and touch. Therefore, the main frame body 41 and the emission side frame body 43 may not be in complete contact with each other but may be slightly separated from each other.

Since the structure of each part of the refractometer other than the cell 2 can be the same as that of the conventional refractometer shown in FIG. 4, its explanation is omitted. The operation of the refractometer employing the cell 2 is basically the same as the conventional one shown in FIG. That is, as described above, the cell 2 of this embodiment does not have the reference mobile phase circulating portion, but in this case as well, the refracted light emitted from the cell 2 flows inside the main frame body 41. The angle changes slightly depending on the composition of the sample. Therefore, the reference mobile phase is circulated in advance to store the irradiation position in the light receiving unit in the memory, and the component detection can be performed by comparing the irradiation position when the sample is circulated and the stored irradiation position. You can do it. Further, in the case of monitoring a transportation pipe in a plant, it is used that the irradiation position at the light receiving portion is displaced due to a slight change in the refractive index when impurities are mixed in the sample. That is, the irradiation position when an appropriate sample is circulated is stored in advance, and the deviation of the irradiation position due to the mixing of impurities is constantly monitored.

Next, a refractometer having an explosion-proof structure in which the cell 2 as described above is preferably used will be described. FIG. 3 is a block diagram of a refractometer in which the cell shown in FIGS. 1 and 2 is preferably adopted. The case where the explosion-proof structure is required is, as described above, the case of detection in a dangerous place such as the presence of a flammable substance in the surroundings. The refractometer shown in FIG. 3 includes a detection unit 6 in which the cells shown in FIGS. 1 and 2 are incorporated in an optical system as shown in FIG. 4 and accommodated therein, and an operation unit 7 for operating each part of the detection unit 6. The detection unit 6 and the operation unit 7 are completely separated from each other. Then, the detection unit 6 is arranged in a dangerous place, and the operation unit 7 is arranged in a safe place.

The detection unit 6 is entirely covered with an explosion-proof box 61. The interior of the explosion-proof box 61 is supplied with air by a supply air blower 62 that inhales in a safe place. Due to this air supply, the interior of the explosion-proof box 61 is pressurized higher than the ambient pressure, that is, pressurized. It is in the state of being Further, the pressure difference between the internal pressure of the explosion-proof box 61 and the ambient pressure is constantly monitored by the two pressure sensors 63 and 64, and a monitor signal is sent to the operation unit 7 arranged in a safe place.

The operation unit 7 has all the functions necessary for daily operation of the refractometer. That is, it is provided with a control unit such as on / off of a light source, opening / closing of a valve for circulating a sample, a display unit for a chromatogram output by processing a signal sent from a detection unit, and a recorder. Therefore, all of the daily operations of the refractometer can be remotely operated from a safe place. If this is not possible, the complicated problem of having to stop the operation of the plant or the like and then analyze the sample will be encountered. Further, the operation unit 7 is also provided with a display section for showing a pressure difference between the inside and outside of the explosion-proof box 61 detected by the pressure sensors 63, 64. Therefore, if the internal pressure of the explosion-proof box falls below the ambient pressure for some reason, take emergency measures such as urgently stopping the power supply to the light source to prevent flammable gas from catching fire. Disasters can be prevented in advance.

When the above explosion-proof structure is adopted, considerable pressure is applied to each part of the refractometer. Here, since the cell in the conventional refractometer is formed by bonding glass with an adhesive, it has low pressure resistance and cannot withstand the above pressure. On the other hand, the cell 2 of the refractometer of this embodiment has a metal frame 4
Since 1, 42, 43 and the translucent body 24, 25 made of glass are assembled and produced, very high pressure resistance can be obtained.
Therefore, it can be suitably used for the design of the explosion-proof structure as described above.

As can be seen from the purpose of mechanical pressure resistance, the material of the frames 41, 42, 43 is not limited to metal such as stainless steel. Since the purpose is to obtain a larger pressure resistance than when the whole is made of the material of the light transmitting bodies 24 and 25, the material of the frame bodies 41, 42 and 43 is stronger than the material of the light transmitting bodies 24 and 25. Any material may be used as long as it has a high value. For example, in terms of organic materials,
A material called PEEK (polyetheretherketone) has recently been favored and used as a material with less fouling. Since this PEEK also has a higher pressure resistance strength than glass or the like, it can be used as a material for the frames 41, 42, 43. it can.

Further, although the cell 2 in the above-mentioned embodiment is described as having no reference mobile phase flow section, it is needless to say that the reference mobile phase flow section is provided unlike the conventional cell shown in FIG. It is possible. In this case, FIG. 1 and FIG.
Main frame 41, incident side translucent body 24, incident side frame 42 shown in FIG.
The same group as the above group may be symmetrically arranged on the emission side with the emission side translucent body 25 interposed therebetween. “Symmetrical arrangement” means that the light is transmitted in a point-symmetrical manner with respect to the point on the optical axis of the light-transmitting side light transmissive body 25 (more accurately, the thickness center point on the optical axis). Therefore, in this case, it means "a differential refractometer". Furthermore, the frames 41, 42, 43 and the translucent bodies 24, 25
In addition to the above-mentioned fixing structure, in addition to the above-described screw fixing by sandwiching a cushioning member such as an O-ring, there are many differences such as a fitting structure in which a part of the frame body is a plate spring portion. It is possible to adopt a different structure. The cell 2 having high pressure resistance is also suitable for a refractometer used in a state where the internal pressure of the cell 2, that is, the pressure of the sample to be circulated is high.
That is, according to the experiments by the inventors, it was confirmed that the cell 2 in the above-mentioned embodiment can be used without any trouble even when the internal pressure of the cell 2 is 10 kg / cm 2 or more.

[0024]

As described above, according to the invention described in claim 1 of the present application, the withstand pressure strength of the cell portion is remarkably improved. The refractometer has an excellent effect in a high usage environment.

[Brief description of drawings]

FIG. 1 is a front sectional view schematically showing a cell in an embodiment of a refractometer of the present invention.

FIG. 2 is a plan sectional view of the cell of FIG.

FIG. 3 is a block diagram of a refractometer in which the cell shown in FIGS. 1 and 2 is preferably adopted.

FIG. 4 is a schematic explanatory diagram of a differential refractometer as an example of a conventional refractometer.

FIG. 5 is a diagram showing details of a cell in the refractometer of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light source 2 cell 24 translucent body 25 translucent body 3 detection part 41 frame body 42 frame body 43 frame body

Claims (1)

[Claims] 1. A cell in which a sample made of a fluid is circulated inside and the external pressure becomes atmospheric pressure or more or the internal pressure per square centimeter becomes 10 kg or more, and the sample flowing in the cell is irradiated with light. It has a light source and a detector for detecting refracted light refracted by the sample irradiated with light,
The cell is a translucent body arranged at a position where light passes,
A refractometer, comprising a frame body made of a material having a higher pressure resistance than the translucent body.