JPH0354440A - Ionizing radiation analyzing apparatus - Google Patents

Abstract

PURPOSE:To make it possible to expand the range for analyzing elements and to improve analyzing accuracy by forming the radiation emitting windows of devices constituting an analyzing apparatus such as the irradiation window of a sample cell with thin films comprising boron nitride and the like wherein the content of impurity elements is less and toxicity is not present. CONSTITUTION:A sample cell 1 is filled with a liquid sample. An X-ray tube 10 projects X rays are emitted from the liquid sample by the irradiation of the X rays. The fluorescent rays are split with a spectroscope 20. The fluores cent X rays which are split with the spectroscope 20 are detected with a detec tor 30. This apparatus is composed of said parts. The cell 1 is provided at the halfway of a sample pickup pipe 2 which is connected to the required part of the sample pickup pipe for the liquid sample. The cell 1 is provided in a sample measuring chamber. The radiation projecting window of the cell 1, the radiation projecting window of the detector 30 are formed with thin films comprising boron nitride. Therefore, the minute concentration can be analyzed, and the analyzing range of elements can be expanded.

Description

[Detailed Description of the Invention] 4. The present invention relates to an ionizing radiation analyzer that analyzes target elements in a sample using ionizing radiation such as X-rays, and more specifically, to an ionizing radiation analyzer that uses ionizing radiation such as The present invention relates to an ionizing radiation analyzer that enables safe and easy handling of sample cells and the like.

For example, an ionizing radiation analyzer (for example, a wavelength-dispersive fluorescent X-ray analyzer that uses X-rays as an excitation source) is used for online analysis of the sulfur content in heavy oil C at oil refinery plants. , a flow-type sample cell filled with a liquid sample;
A radiation source that irradiates a liquid sample filled in a sample cell with ionizing radiation, and fluorescence x! emitted from the liquid sample by irradiation with ionizing radiation. ! It has a detector that detects it.

The sample cell is installed by being inserted in the middle of a heavy oil C sample collection pipe connected to the required location of the oil refining plant. A liquid sample consisting of C heavy oil is continuously collected through a sample collection tube, and flows while filling the sample cell.

An X-ray tube as a radiation source consists of a bipolar vacuum tube that accelerates thermoelectrons emitted from a filament and collides with a target to generate X XI. The generated X-rays are taken out to the outside through the radiation emission window of the X-ray tube.
Fired towards the sample cell.

The X-rays emitted toward the sample cell are received through the radiation irradiation window of the sample cell, and are irradiated onto the liquid sample flowing inside the sample cell.

When a liquid sample in a sample cell is irradiated with X-rays, the X-rays collide with electrons in the orbits of atoms, creating empty or deficient orbits of electrons, and introducing electrons from outer orbits into those orbits. As it moves, it generates and emits fluorescent X-rays (characteristic X-rays). This emitted light X! The intensity of it corresponds to the concentration of the element in the night body sample.

Fluorescent X-rays emitted from the liquid sample within the sample cell are emitted to the outside through the irradiation window of the sample cell. The spectrometer is made of a single crystal suitable for diffraction according to the wavelength range of fluorescent X-rays, and reflects the emitted fluorescent X-rays at a reflection angle (
θ) and spectroscopy.

The fluorescent rays separated by the spectrometer are received by a detector through a radiation receiving window and detected.

The detector scans while satisfying the Bragg reflection condition to detect fluorescent X-rays. For example, when analyzing the sulfur content in C heavy oil, sulfur can be measured by setting the position at a position where the characteristic X-ray of sulfur satisfies the Bragg reflection condition.

However, in the conventional ionizing radiation analyzer mentioned above, there are no windows through which the radiation of the equipment that makes up the analyzer passes, namely the emission window of the X-ray tube, the irradiation window of the sample cell, and the light reception window of the detector. In the past, thin films of beryllium (Be) and surface-oxidized beryllium (Bed) were used as window materials. This is because beryllium (including perilia) has excellent features such as low absorption of ionizing radiation such as X-rays and no deterioration of measurement accuracy in terms of the intensity of ionizing radiation, and beryllium has high mechanical strength. be.

However, the purity of beryllium is only about 98-99%, and it is classified as an impurity element by Fed. 18%, Afl.
0.16%, CO. l5%, Nip. 10%, Mg0.
08%, Si0.08%, Tie. 05% etc. exist.

For this reason, the elements that can be analyzed by the ionizing radiation analyzer are limited, and even if they can be analyzed, it is impossible to measure trace concentrations, which has the disadvantage of poor measurement accuracy. In addition, beryllium is toxic and has negative effects on the human body.
It also lacked safety and was not easy to handle. Particularly in the case of a sample cell, the irradiation window must be replaced periodically, and this must be done manually by a worker, which is extremely dangerous.

The above problems are basically the same in the case of batch-type ionizing radiation analyzers that analyze liquid samples in batches. In the case of a batch-type sample cell, it is necessary to manually insert the liquid sample into the cell, so if the irradiation window is made of beryllium, the risk increases further.

Therefore, in view of the above-mentioned current situation, it is an object of the present invention to form a radiation passing window of a device constituting an analysis device, such as a radiation irradiation window of a sample cell, with a window material that has a low content of impurity elements and is non-toxic. Therefore, it is an object of the present invention to provide an ionizing radiation analyzer that can expand the range of elements to be analyzed and is safe and easy to handle.

The above-mentioned object of the present invention is achieved by the ionizing radiation analyzer of the present invention. In summary, the present invention includes a sample cell that holds a measurement sample, a radiation source that irradiates the measurement sample held in the sample cell with ionizing radiation, and a radiation source that emits radiation from the measurement sample by irradiating the ionizing radiation. Light XI! In an ionizing radiation analyzer comprising a detector for detecting the
This is an ionizing radiation analysis device characterized by being formed of a thin film of a boron compound. Examples of the boron compound include boron nitride, boron carbide, and boron. According to one aspect of the present invention, the boron compound is boron nitride or boron carbide.

The present invention will be explained in detail below.

From the above-mentioned viewpoint, the present inventor has made it possible to improve analysis efficiency by forming the radiation passing window of the equipment that constitutes the analysis device, such as the radiation irradiation window of the sample cell, with a non-toxic window material with a low content of impurity elements. We have conducted extensive research in order to develop an ionizing radiation analyzer that is safe and easy to handle, and which makes it possible to expand the range of elements. As a result, we found the following.

In other words, boron compounds such as boron nitride and boron carbide are ceramic materials that are non-toxic and have excellent mechanical strength and heat resistance, but were conventionally considered to have poor transparency to radiation including X-rays. According to research conducted by the inventor,
These thin films of boron nitride, boron carbide, etc. are highly transparent to radiation, and if they are made into a somewhat thin film of 500 μm or less and used for the radiation irradiation window of the sample cell, the attenuation of ionizing radiation can be reduced and the measurement accuracy can be sufficiently increased. can be maintained. The thickness of these thin films of boron nitride, boron carbide, etc. is 1
The thickness is 0 to 500 μm, preferably 10 to 300 μm, more preferably 10 to 200 μm, and may be appropriately selected depending on the conditions such as the pressure at the location of use, the element to be measured, and the temperature. In addition, the purity of these boron nitrides, boron carbides, etc. is, for example, 9
Since a high purity of 9.9% or more is easily obtained and there are few impurity elements, there is almost no effect of impurity elements even when used in a radiation irradiation window of a sample cell. Therefore, trace analysis is possible and the range of elements that can be analyzed is expanded. Furthermore, an ionizing radiation analyzer that is non-toxic and easy to handle can be obtained.

The present invention has been achieved based on the above findings.

FIG. 1 is a block diagram schematically showing an embodiment of the ionizing radiation analyzer of the present invention. This ionizing radiation analyzer is
For example, it is used for online analysis of sulfur content in C heavy oil in petroleum refinery plants. This analyzer is a wavelength dispersive fluorescent X-ray analyzer.

In FIG. 1, l is a flow-type sample cell, and the ionizing radiation analyzer of the present invention has a flow-type sample cell l filled with a liquid sample, and a liquid sample filled in the sample cell l, as in the conventional case. an X-ray tube 10 that irradiates X-rays as ionizing radiation; a spectrometer 20 that spectrally spectra fluorescent X-rays emitted from a liquid sample by irradiation with X-rays; It consists of a detector 30 that detects the line.

The sample cell 1 is installed in a sample measurement chamber (not shown) by being inserted in the middle of a sample collection tube for a target liquid sample, for example, a C heavy oil sample collection tube 2 connected to a required location in an oil refinery plant.

As shown in FIG. 2, the sample cell 1 consists of an annular container with a circular opening 3 on one side.
is provided with a radiation exposure window 4. The inner surface of the sample cell 1 opposite to the opening 3 is bulged toward the opening 3 in order to prevent foreign matter from adhering to the inside of the window 4 of the sample cell 1. The irradiation window 4 is attached to the opening 3 by being inserted between the flanges 5 of the opening 3 and fixed with bolts 6.

According to the present invention, the radiobiliary window 4 has a purity of 99.9.
% or more, and in this example, it is a thin film of boron nitride with a purity of 99.999%. If the purity of the boron nitride thin film is less than 99.9%, there are too many impurity elements and their influence is large, making it impossible to perform trace analysis or to expand the range of elements that can be analyzed.

In order to obtain such a thin film of high purity boron nitride, for example, the CVD method (chemical vapor deposition method) using boron trichloride and ammonia can be used;
A thin film with high purity of 9% or more can be easily obtained. The thickness of the thin layer is adjusted by polishing.

The thickness of the irradiation window 4 is 500 μm or less.

When the thickness of the irradiation window 4 exceeds 500 μm, the attenuation of radiation due to the thickness cannot be ignored, leading to a decrease in measurement accuracy in terms of radiation intensity. On the other hand, if the thickness of the irradiation window 4 is too thin, the irradiation window 4 will be easily destroyed by a liquid sample collected online from a plant or the like and subjected to pressure. Liquid sample force In case of SC heavy oil, usually 2 to 10 kg/ct
Since a pressure of about rl is applied, in that case, the thickness of the irradiation window 4 only needs to be about 100 μm. The size of the irradiation window 4 is usually about 30 mmφ in diameter.

A liquid sample consisting of C heavy oil is continuously collected through a sample collection tube and flows while filling the sample cell 1.

The X-ray tube 10 is installed on the side of the radiation irradiation window 4 of the sample cell 1, and its tip is directed toward the radiation irradiation window 4 of the sample cell 1, with its tip facing diagonally upward into an irradiation chamber (not shown).

As shown in FIG. 3, the X-ray tube 10 generates X-rays by accelerating the generated thermoelectrons with an applied voltage and colliding with a filament 12 as a cathode that generates thermoelectrons in the tube 11. It consists of a bipolar vacuum tube provided with a target 13 as a generating anode. In the case of a vertical tube, a radiation emitting window 14 for taking out generated X-rays to the outside is provided on the distal end surface of the tube 1O, as shown in the figure.

According to the invention, the radiation emitting window 14 is provided in the sample cell 1.
As with the radiation irradiation window 4, the purity is 99.9% or more,
In this embodiment, it is made of a thin film of boron nitride with a high purity of 99.999%. The thickness of the emission window 14 made of this thin film of boron nitride is sufficient as long as it can withstand the vacuum of the X-ray tube 10.
For example, it is about 100 to 200 μm. X-rays generated in the X-ray tube 10 are emitted toward the sample cell l through the emission window 14, are received through the radiation irradiation window 4 of the sample cell 1, and are caused to flow, filling the sample cell l. The liquid sample is irradiated.

When the liquid sample in the sample cell 1 is irradiated with X II,
The element generates and emits fluorescent X-rays (characteristic X-rays).
The emitted fluorescent X-rays are emitted to the outside through the irradiation window 4 of the sample cell 1, and are passed through the spectrometer 20 through a slit (not shown) or the like.
guided by.

The spectrometers 20 are made of a single crystal suitable for Bragg diffraction depending on the wavelength of fluorescent X-rays, and a plurality of them are installed in a spectroscopy chamber (not shown). The spectrometer 20 diffracts the guided fluorescence X II at a reflection angle (θ) corresponding to a wavelength that satisfies Bragg's reflection condition and spectrally spectra it.

Fluorescent X-rays separated by the spectroscope 20 are guided to a detector 30 outside the spectroscopic chamber through a slit (not shown).

The detector 30 is a gas-filled type detector, and as shown in FIG. 3, a platinum core wire 32 connected to an external detection circuit (not shown) is placed inside a container 31 filled with a rare gas such as Xe. It is stretched out. A radiation receiving window 33 for receiving fluorescent X-rays separated by the spectroscope 20 is provided on the surface of the detector 30 facing the spectrometer 20 . The detector 30 receives and scans the light while satisfying the Bragg reflection angle using a rotating device (not shown), and detects the current flowing through the platinum core wire 32 using a detection circuit using the ionization effect of the rare gas caused by the received fluorescent X-rays. By this, fluorescent X-rays are detected.

According to the present invention, the radiation receiving window 33 is provided in the sample cell l.
As with the radiation irradiation window 4 and the like, it is made of a thin film of boron nitride with a purity of 99.9% or more, in this embodiment 99.999%. The thickness of the light receiving window 43 made of a thin film of boron nitride is sufficient as long as it can withstand the low pressure of the detector 30.
Approximately 0 to 20 μm is sufficient. The ionizing radiation analyzer of the present invention is configured as described above. According to this, the radiation irradiation window 4, x of the sample cell l
I! ! By forming the radiation emitting window l4 of the tube 10 and the radiation receiving window 33 of the detector 30 with a thin film of boron nitride, the content of impurity elements is reduced, making it possible to analyze trace concentrations. The range of elements can be expanded. Further, boron nitride is non-toxic, making the sample cell 1, the X-ray tube 10, and the detector 30 safe and easy to handle. Particularly in the case of the sample cell 1, the radiation irradiation window 4 needs to be replaced periodically, and this has to be done manually by a worker, which was extremely dangerous in the past, but according to the present invention, The irradiation window 4 can be replaced without any danger.

In the above embodiment, the irradiation window 4 of the sample cell l of the ionizing radiation analyzer, the emission window 14 of the X-ray tube 10, and the detector 30
The light receiving window 33 was entirely formed of a thin film of boron nitride, but
This is not necessarily limited to items with a high degree of safety requirement,
For example, only the irradiation window 4 of the sample cell 1 may be used. Further, a thin film of boron carbide can be used instead of a thin film of boron nitride, and the same effect can be obtained. Furthermore, it is also possible to use boron. Further, although the X-ray tube 10 has been described as an example of the ionizing radiation source, other radiation sources such as RI can also be used. About the detector, detector 30
Detectors such as scintillation counters and semiconductor detectors as well as proportional counters can be used. Furthermore, although an online type ionizing radiation analyzer using a flow type cell as the sample cell 1 has been shown, the present invention is not limited thereto, and can also be applied to a batch type ionizing radiation analyzer using a batch type cell. Equally applicable.

Fruit”L example Examples of the present invention will be described.

Using the ionizing radiation analyzer of the present invention and the conventional ionizing radiation analyzer, nickel (Ni) and vanadium (V) contained in a heavy gas oil fraction were analyzed in batches.

The analyzer of the present invention uses a boron nitride thin film only in the radiation irradiation window of the sample cell, and the boron nitride thin film has a purity of 9.
High purity of 9.999%, thickness 200μm, irradiation area (
The opening area of the sample cell was 30 mmφ. The beryllium thin film used for the radiation irradiation window of the sample cell of the conventional analyzer had a thickness of 150 μm, and the irradiation area was similarly 30 mmφ.

Other aspects were the same for both the present invention and the conventional X-ray tube: the radiation emitting window of the X-ray tube was made of beryllium with a thickness of 120 μm, the target was rhodium, the X-ray generation voltage was 50 kV, and the generated current was 50 mA. The spectroscopic crystal used was LiF (200), and the X-ray path was in an air atmosphere. Also, the detector is Xe
With a gas flow type detector, that fluorescent X! ! Polypropylene with a thickness of 1 μm was used for the light receiving window.

The measurement results are shown in Table 1.

In Table 1, the coefficient of variation (CV%)=standard deviation/average value xlOO, and the smaller the coefficient of variation (CV%), the higher the accuracy of the analysis. In Table 1, the chemical analysis value of the high concentration sample is Ni: 15 ppm. V:
The chemical analysis value of the 56 ppm low concentration sample was Ni: 3. l
ppm, ■2 8.5 ppm.

Table 1 (unit: p pm) As shown in Table 1, the coefficient of variation (CV%) is smaller when boron nitride is used than when beryllium is used for the radiation irradiation window of the sample cell. It can be seen that highly accurate analysis is possible with the analyzer according to the present invention. Further, since the difference between chemical analysis values and measured values is smaller when boron nitride is used, highly reliable measurement results can be obtained with the analyzer according to the present invention.

4. As explained above, in the ionizing radiation analyzer of the present invention, the radiation passing window of the equipment constituting the analyzer, such as the irradiation window of the sample cell, is made of nitrided material that has a low content of impurity elements and is non-toxic. Since it is formed from a thin film of boron, boron carbide, or boron, the analysis precision is improved, the range of elements to be analyzed is expanded, and handling of the sample cell etc. becomes safe and easy.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing an embodiment of the ionizing radiation analyzer of the present invention. FIG. 2 is a sectional view showing a sample cell of the analyzer of FIG. 1. Figure 3 shows the same <Xi! It is a sectional view showing a tube. FIG. 4 is a cross-sectional view of the detector. l 2 3 1 0 1 4 20 3 0 33 : Sample cell: Liquid sample collection tube: Irradiation window: X-ray tube: Emission window 2 Spectrometer: Detector: Light receiving window

Claims (1)

[Claims] 1) a sample cell that holds a measurement sample; a radiation source that irradiates the measurement sample held in the sample cell with ionizing radiation; and a radiation source that irradiates the measurement sample with the ionizing radiation. An ionizing radiation analyzer comprising: a radiation irradiation window of the sample cell, a radiation emission window of the radiation source, or a fluorescence X-ray detector of the detector;
An ionizing radiation analyzer characterized in that at least one of the line-receiving windows is formed of a thin film of a boron compound. 2) The ionizing radiation analyzer according to claim 1, wherein the boron compound comprises boron nitride or boron carbide.