JPH04355355A - Method of detecting pollution of window material for fluorescence x-ray analysis - Google Patents

Abstract

PURPOSE:To detect pollution of a window material automatically for a fluorescence X-ray analyzer which analyzes a analysis sample comprising a liquid. CONSTITUTION:Two types of calibration samples 1H and 1L are set alternately at an irradiation point P beforehand and both the calibration samples 1H and 1L with primary X rays B1 to measure first and second reference intensities IH0 and IL0 of the fluorescence X rays B2. Then, prior to an analysis on an analysis sample 1 on the operation day, both the calibration samples 1H and 1L are irradiated with the primary X rays B1 to measure first and second measured intensities IH1 and IL1 of the fluorescence X rays B2. Thereafter, when a value as obtained by dividing the first measured intensity IH1 by the first reference intensity IH0 is smaller than a first threshold A (A is smaller than 1.0) while a value as obtained by dividing the second measured intensity IL1 by the second reference intensity IL0 is larger than the second threshold value B (B is larger than 1.0), the window material 6 is determined to be polluted by the analysis sample.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting contamination of a window material in a fluorescent X-ray analyzer in which a container is filled with a liquid sample to be analyzed, such as petroleum.

0002

2. Description of the Related Art Generally, when a liquid analysis sample is filled in a container and subjected to fluorescent X-ray analysis, an X-ray source and an X-ray detector are placed below the analysis sample with a window material interposed therebetween. An example of this type of fluorescent X-ray analyzer is shown in FIG.

In FIG. 1, an analysis sample 1 such as light oil or heavy oil is filled in a container 2 and placed on a sample placement window 3. The lower part of the container 2 is filled with an analysis sample 1 covered with a thin film 4. Note that the thin film 4 is held between a cylindrical inner container 2a and an outer container 2b.

A window member 6 is provided below the container 2 filled with the analysis sample 1, and an X-ray tube (radiation source) 7 and an X-ray detector 8 are further arranged below the window member 6. . A filter 10 is provided above the X-ray detector 8 . The window material 6 is for preventing the filter 10, the X-ray tube 7, the X-ray detector 8, etc. from getting dirty.

[0005] Next, the analysis method will be briefly explained. Primary X-rays (radiation) B1 emitted from the X-ray tube 7
is irradiated onto the analysis sample 1 inside the container 2 through the window material 6. The atoms of the analysis sample 1 that have received the primary X-rays B1 are excited and generate fluorescent X-rays B2 unique to that element. Fluorescent X-rays B2 due to components other than sulfur are absorbed by the secondary filter 10, and are incident on the X-ray detector 8, where the X-ray intensity is detected. From this detection result, the concentration of sulfur in the analysis sample 1 is determined.

By the way, in fluorescent X-ray analysis, the accuracy of analysis is improved by calibrating changes in X-ray intensity (device drift) caused by changes in the analyzer itself over time. To perform calibration, prepare the following two types of calibration samples. The first calibration sample 1H is more sensitive to the element to be detected than the analysis sample 1 (
The intensity of fluorescent X-rays of the element to be detected (sulfur) or X-rays with energy similar to it is high, while the second calibration sample 1L has a higher intensity of fluorescent X-rays of the element to be detected (sulfur) or energy similar to it than analysis sample 1. X-ray intensity is set low. Both calibration samples 1H and 1L are not necessarily analysis sample 1.
It doesn't have to be the same material.

[0007] The X-ray intensity I of the analysis sample 1 with device drift calibrated is determined based on the following equations (1) to (3). I=Im ・α+β
...(1) α=(IH0-IL0)/(IH1-
IL1) ...(2) β=IH0-IH1・α
...(3) Im: Measured intensity α, β of the analysis sample: Drift correction coefficient IH0: Reference intensity of the first calibration sample IL0: Reference intensity of the second calibration sample IH1: Measured intensity of the first calibration sample IL1: Second calibration Measured intensity of sample

[0008]

By the way, in this type of fluorescent X-ray analysis of a liquid sample, the window material 6 shown in FIG. 1 may be contaminated with the liquid sample. For example, container 2 in Figure 1
The analysis sample 1 inside may seep out along the thin film 4 and adhere to the window material 6. In such a case, fluorescent X-rays B2 are also generated from the contaminants attached to the window material 6, and fluorescent X-rays B2 generated from the analysis sample 1 are absorbed by the contaminants, so even if calibration is performed, Accurate analysis becomes impossible. Therefore, it is necessary to replace the window material 6 as appropriate.

[0009] Here, even if the contamination of the window material 6 cannot be visually detected, it may not be ignored as an analysis error. Therefore, the contamination of the window material 6 is detected,
It becomes necessary to make a judgment. The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a detection method for detecting contamination of a window material in a fluorescent X-ray analyzer that analyzes an analysis sample made of a liquid.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention measures the X-ray intensities of the first and second calibration samples 1H and 1L shown in FIG. The first and second measured values IH0 and IL0 are obtained. After this, the X-ray intensities of the first and second calibration samples 1H and 1L are measured, and the later first and second measurement values I
Find H1 and IL1. As shown in FIG. 2(b), the first measured value IH1 after the above is smaller than the first measured value IH0, and the second measured value IL1 after the above is the second measured value IH0.
When it becomes larger than L0, it is determined that the window material 6 is contaminated by the analysis sample.

[0011]

[Operation] The principle of this invention will be explained using FIGS. 1 and 2. When the window material 6 is not contaminated and device drift occurs, the first and second calibration samples 1H,
The measured values IH1 and IL1 after 1L both drift in the same direction, as shown in FIG. 2(a).

On the other hand, if the window material 6 is contaminated with components of the analysis sample, in the case of the first calibration sample 1H with strong X-ray intensity,
The intensity of the fluorescent X-ray B2 generated from the deposit is higher than the first one.
Since the intensity of the fluorescent X-rays B2 generated from the calibration sample 1H is smaller than the intensity of the fluorescent X-rays absorbed by the deposits, it is shown in Fig. 2(
As in b), the subsequent first measured value IH1 decreases. Conversely, in the case of the second calibration sample 1L, which has a low X-ray intensity, the intensity of the fluorescent X-rays B2 generated from the deposits is higher, and the fluorescence X-rays B2 generated from the second calibration sample 1L are absorbed by the deposits. Since the intensity is greater than the intensity of fluorescent X-rays, the subsequent second measured value IL1 becomes larger.

Therefore, when the later first measured value IH1 is smaller than the earlier first measured value IH0 and the later second measured value IL1 is larger than the earlier second measured value IL0, the window material 6 can be determined to be contaminated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method of the present invention will be described below with reference to the drawings. The analyzer and calibration samples 1H and 1L used are the same as those described in the conventional example.

In advance, both calibration samples 1H and 1L in FIG. 2 reference intensities (previous first and second measurement values) IH0, I
Measure L0. Next, before analyzing analysis sample 1 on the day, both calibration samples 1H and 1L are irradiated with primary X-rays B1, and the first and second measured intensities of fluorescent X-rays B2 (later first and second measured values ) Measure IH1 and IL1.

[0016] After that, each of the above-mentioned intensities IH0, IH1, IL
0, IL1, the value obtained by dividing the first measured intensity IH1 by the first reference intensity IH0 is the first threshold value A (A is 1.0
, and the value obtained by dividing the second measured intensity IL1 by the second reference intensity IL0 is larger than the second threshold B (B is a value larger than 1.0). , it is determined that the window material 6 is contaminated by the analysis sample. That is, if the following equations (4) and (5) are satisfied, it is determined that the window material 6 is contaminated. IH1/IH0<A...(4) IL1/IL0>B
...(5)

[0017] Both threshold values A and B mentioned above are set for each analyzer, but values closer to 1.0 are used when more accurate analysis is required. Generally, the first threshold value A
is set to be sufficiently smaller than the rate of variation due to statistical variations in X-ray intensity, for example, 0.95, and the second threshold value B is set to a sufficiently large value, for example, about 1.05. Note that if it is determined that the window material 6 is contaminated, an alarm message is issued to notify the operator.

In the above determination method, the first calibration sample 1H
has stronger X-ray intensity than analysis sample 1. Therefore, if the window material 6 is contaminated with the analysis sample 1, the first measured intensity IH1 in FIG.
It becomes smaller than the reference intensity IH0. On the other hand, the second calibration sample 1L has a weaker X-ray intensity than the analysis sample 1. Therefore,
Conversely, when the window material 6 is contaminated with the analysis sample 1, the second measured intensity IL1 becomes larger than the second reference intensity IL0. Therefore, if both the above equations (4) and (5) are satisfied, it can be determined that the window material 6 is contaminated.

By the way, the X-ray intensity varies not only due to contamination of the window material 6 but also due to changes over time. Therefore, in the method of comparing the reference intensity and the currently measured intensity, it may not be possible to correctly determine the contamination of the window material 6 due to the influence of changes over time. For this reason, the reference intensities IH0 and IL0 of each calibration sample 1H and 1L, and the measurement intensity IH
1. Rather than comparing with IL1, each calibration sample 1H, 1L
The previous measured intensity IH1, IL1 and the current measured intensity IH
2, it is preferable to compare with IL2.

For example, the value obtained by dividing the current first measurement intensity IH2 by the previous first measurement intensity IH1 is the first threshold value A1.
, and the value obtained by dividing the current second measurement value IL2 by the immediately preceding second measurement intensity IL1 is the second threshold B1.
If it is larger than , it is determined that the analysis sample is attached to the window material 6. That is, if the following equations (6) and (7) are satisfied instead of the above-mentioned equations (4) and (5), it is determined that the window material 6 is contaminated. IH2/IH1<A1...(6) IL2/IL1>B1...(7) A1: Value smaller than 1.0 B1: Value larger than 1.0

[0021] It should be noted that the analyzer is the first and second
If the measured intensities IH1, IL1 are not stored, the immediately preceding first and second measured intensities IH1, IL1 are determined from equations (8) and (9) below. IH1=(IH0-β)/αIL1=(IL0-β)/
αα, β: Drift correction coefficient of the previous time

[0022]

As explained above, according to the present invention, the first calibration sample 1H has an X-ray intensity higher than that of the analysis sample 1, and the second calibration sample 1L has an X-ray intensity lower than that of the analysis sample 1. , the later first measured value IH1 is the earlier first measured value IH
Since it is determined that the window material 6 is dirty when the second measured value IL1 is smaller than 0 and the second measured value IL1 is larger than the second measured value IL0, it is determined that the window material 6 is dirty. 6 contamination can be detected.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a general fluorescent X-ray analyzer.

[Figure 2] (a) is a characteristic diagram showing the relationship between standard strength and measured strength when the window material is not contaminated with analysis samples, (b)
is a characteristic diagram showing the relationship between the reference intensity and the measured intensity when the window material is contaminated with an analysis sample.

[Explanation of symbols]

1... Analysis sample, 1H... First calibration sample, 1L... Second calibration sample, 6... Window material, 7... Radiation source (X-ray tube), 8... X-ray detector, B1... Radiation (primary X-ray), B2...Fluorescent X-ray, IH
0...first measured value before (first reference intensity), IH1...first measured value after (first measured intensity), IL0...second measured value before (
second reference intensity), second measured value after IL1 (second measured intensity).

Claims (1)

[Claims] 1. A radiation source and an X-ray detector are placed below an analysis sample made of a liquid with a window material interposed therebetween, and radiation is irradiated from the radiation source to the analysis sample through the window material. A method for detecting contamination on a window material in an X-ray fluorescence analyzer, which performs elemental analysis of an analysis sample by detecting the X-ray intensity from the sample to be detected using the X-ray detector. A first calibration sample in which the X-ray intensity of X-rays or energy similar to it is higher than that of the analysis sample, and a second calibration sample in which the intensity of fluorescent X-rays of the element to be detected or X-rays with energy similar to it is lower than that of the analysis sample. , and measure the X-ray intensity of the first and second calibration samples in advance to obtain the first and second measurement values, and then measure the X-ray intensity of the first and second calibration samples.
measuring the line intensity to obtain subsequent first and second measurements;
When the first measured value after the above is smaller than the first measured value and the second measured value after the above is larger than the second measured value, it is determined that the window material is dirty. A method for detecting contamination of window materials in a fluorescent X-ray analyzer.