JPS6233545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluorescent X-ray sulfur analyzer that accurately measures the sulfur element content contained in hydrocarbon compounds such as petroleum, even in the presence of pure substances such as heavy metals. be.

A conventional device of this type is shown in FIG. In the figure, 1 is a radiation source, for example
An RI source such as ⁵⁵ Fe or an X-ray tube with a titanium or tungsten anode is used. 2
3 is an X-ray detector that detects characteristic X-rays of sulfur generated from the sample; 4 is an X-ray detector interposed between the sample portion 2 and the detector 3; This is a filter for removing interfering X-rays.

Fluorescence X-ray analysis In the so-called excitation method, excitation radiation generated from a radiation source 1 is emitted onto a sample housed in a sample section 2, and X-rays such as characteristic X-rays of sulfur generated from the sample section 2 are detected by X-rays. Detected by device 3. The detected X-rays further detected here are subjected to energy analysis using a pulse height discriminator (not shown).
The sulfur content is determined by differentially counting the characteristic X-ray intensity of sulfur.

The signal count rate in the detection system of the conventional device described above can generally be expressed by the following equation (1).

Ip=I・K・Pμ _S・S/(μ _H ′+μ _H ″) H + (μ _C ′+ μ _C ″) _C + (μ _S ′+ μ _S ″)・S (1) Here, K; Detection efficiency P: Fluorescence yield of sulfur element (approximately 5×10 ^-2 ) H, C, S: Weight of each composition per unit volume (g/cm ³ ) μH′, _μC ′, _μS ′ ; Total mass absorption coefficient of each constituent element for excitation radiation (cm ² /g) μ _H ″, μ _C ″, μ _S ″; Total mass absorption of each constituent element at the characteristic X-ray energy of sulfur (approximately 2.3 kev) Coefficient (cm ² /g) μ _S : Photoelectric absorption coefficient of sulfur element for excitation radiation (cm ² /g) Ip : Characteristic X-ray intensity of sulfur (cps) I : Excitation radiation intensity (cps) In the formula, mass absorption coefficient ( μ) is energy dependent, and in particular, the photoelectric effect coefficient (μ _S ) value of sulfur makes a large contribution to detection efficiency. This is given by the excitation radiation energy, and when the radiation source 1 is a γ-ray source in the apparatus shown in Figure 1, approximately 5.9ke monochromatic X of ^55Fe
In the case of titanium, its monochromatic characteristic X-rays, in the case of tungsten, bremsstrahlung secondary radiation, etc. are generally used as the source of excitation radiation, depending on the anode material in the case of X-ray tubes.

However, hydrocarbon compounds such as petroleum contain some elemental chlorine, which causes an error in determining the sulfur content during sulfur analysis. The reason for this is that the excitation radiation source shown in FIG. 1 has conventionally been used, and upon excitation irradiation, the chlorine element, which has an atomic number one higher than the sulfur element, is excited. Therefore, in the process of X-ray detection, some of the characteristic X-rays of chlorine become virtually indistinguishable from the characteristic X-rays of sulfur due to the limited energy resolution of the detector. This cannot be discriminated even by a wave height discriminator attached at a subsequent stage. However, although a considerable improvement effect can be expected by shifting the upper and lower limit setting positions of the wave height discriminator and narrowing the window width, this comes at the cost of a decrease in the counting efficiency of the characteristic X-rays of sulfur. .

Therefore, in the conventional example, in order to prevent the influence of this chlorine,
A filter 4 is interposed between the sample section 2 and the detector 3. In the case of petroleum sulfur analysis, a substance containing sulfur is used as a filter material, and the energy versus mass absorption coefficient characteristic (μ(E)) of sulfur is utilized.

However, this filter is difficult to manufacture and is generally not very effective.

This is because a filter is placed on the passage of the detected X-rays, and due to the absorption characteristics of the filter,
While it absorbs a considerable amount of the characteristic X-rays of chlorine,
This is because the characteristic X-rays of sulfur are also accompanied by a certain degree of transmission loss.

Since the conventional fluorescent X-ray sulfur analyzer is configured as described above, it is affected by the chlorine element in petroleum. Moreover, although a filter is used to prevent this, it is difficult to manufacture and has drawbacks such as being ineffective.

This invention was made to eliminate the drawbacks of the conventional ones as mentioned above, and in addition to the primary radiation source,
A substance whose main component is chlorine and whose coexisting constituent elements include an element with an atomic number smaller than that of the chlorine atom (hereinafter referred to as a chlorine-containing substance), which generates characteristic X-rays when irradiated with primary radiation2 Fluorescent X-ray sulfur analysis equipment that can virtually eliminate the effects of chlorine elements contained in petroleum without using filters or other means by configuring a radiation source with a target that serves as a secondary radiation source. is intended to provide.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, reference numerals 1, 2, and 3 indicate the same parts as in the conventional device described above, and the explanation thereof will be omitted. Reference numeral 5 denotes a target which is made of a substance containing chlorine and which generates characteristic X-rays upon receiving radiation from the primary radiation source 1, and serves as a secondary X-ray source. (Note that 1 constitutes a primary radiation source.) Next, the operation will be explained. As the excitation radiation source, an X-ray tube is used as the primary radiation source 1, and
Consider a configuration in which the target 5 as a secondary radiation source is made of a material containing chlorine.

When primary excitation rays generated from the primary radiation source 1 are irradiated onto the target 5, scattered rays and characteristic X-rays are generated as a result of interaction with the target material. If the X-ray tube anode high voltage is adjusted here and the X-ray output maximum wavelength and average wavelength are changed, the characteristic
It is possible to increase the intensity ratio of generated radiation and scattered radiation. Therefore, a secondary radiation source that emits characteristic monochromatic X-rays specific to the material element can be easily obtained from the target surface. This can serve as a high-quality excitation radiation source for fluorescent X-ray petroleum sulfur analysis.

Next, as a specific method, external target 5
In the above configuration in which chlorine is added, if a substance containing chlorine is used as the target material, monochromatic X-rays characteristic of chlorine are obtained. Furthermore, by using this as a secondary X-ray source and irradiating the sample section 2 containing a sample of petroleum or the like, it is possible to efficiently excite the sulfur element, which is the substance to be measured, in the sample. On the other hand, since the chlorine element, which is an interfering element in the sample, is not excited by this excitation energy, characteristic X-rays of chlorine are not generated.
Conventional radiation sources produce characteristic X-rays of chlorine,
In contrast, the radiation source of the present invention eliminates the generation of interfering X-rays due to chlorine in the sample, compared to the case where a portion of the sulfur signal was included in the measurement during the detection process, causing an error in analysis and quantification and causing an adverse effect. This is something that can be prevented.

Practically speaking, as a material for the target 5, a substance composed of chlorine and an element having a smaller atomic number than chlorine is preferably used. The reason for this is that these elements have a smaller absorption effect than chlorine, so the loss in the characteristic X-ray emission intensity of chlorine is slight. In addition, the characteristic KX-rays based on the absorption effects of these elements have low energy and do not excite either chlorine or sulfur, so they do not cause interference. Specifically, sodium chloride is preferably used as the secondary radiation source target. A film is applied to the surface by conventional techniques to prevent deliquescence. Alternatively, a chlorine-containing organic compound such as vinyl chloride can also be used.

Furthermore, the internal anode of the X-ray tube does not need to be particularly limited in terms of material, and any material can be suitably used.

In the above example, the arrangement of each component is provided in a simple manner, but the arrangement relationship may be changed to the extent that geometrical efficiency is improved, or the dimensions, shape, etc. of the external target may be changed. , the same effect can be achieved even if the change is made if the source efficiency can be improved.

Further, the primary radiation source 1 is not limited to an X-ray tube, and may of course be one that emits gamma rays.

As described above, according to the present invention, a target (secondary radiation source) made of a substance containing chlorine that emits characteristic X-rays by radiation emitted from a primary radiation source such as an X-ray tube is used as an excitation radiation source. ), it is possible to eliminate most of the chlorine errors caused by chlorine contained in hydrocarbon compounds such as petroleum using inexpensive equipment.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional fluorescent X-ray sulfur analyzer, and FIG. 2 is a schematic diagram showing an embodiment of the present invention. 1...Primary radiation source, 2...Sample part, 3...X
Line detector, 5...Target. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A substance consisting of a primary radiation source that generates either X-rays or γ-rays, and a chlorine atom and an element with an atomic number smaller than the chlorine atom, which emits radiation from the primary radiation source. a target that receives and emits first characteristic X-rays; a sample section that receives the first characteristic X-rays from the target; A fluorescent X-ray sulfur analyzer comprising: an X-ray detector that detects characteristic X-rays; and a fluorescent X-ray sulfur analyzer. 2. The fluorescent X-ray sulfur analyzer according to claim 1, which includes a target made of sodium chloride. 3. A fluorescent X-ray sulfur analyzer according to claim 1, which includes a target made of a chlorine-containing organic compound. 4. The fluorescent X-ray sulfur analyzer according to claim 3, wherein the chlorine-containing compound is vinyl chloride.