JPH0628684Y2 - UV Fluorescence Analyzer - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an ultraviolet fluorescence analyzer using an ultraviolet fluorescence analysis method used for measuring the concentration of SO ₂ (sulfur oxide) in the atmosphere, for example. It relates to improved technology.

[Conventional technology]

As an ultraviolet fluorescence analyzer by the above-mentioned ultraviolet fluorescence method, an ultraviolet irradiation light source and a light source light amount detector for monitoring the light amount of the light source are arranged inside the cells at positions corresponding to each other across the fluorescence chamber. In addition, further, in a direction orthogonal to the optical path from the light source to the light source light amount detector and at positions corresponding to each other across the fluorescent chamber, a fluorescent detector and a recessed portion for stray light attenuation are provided. There is something that consists.

In such an ultraviolet fluorescence analyzer, while introducing the sample gas into the fluorescence chamber inside the cell, when the ultraviolet irradiation light source is turned on so as to irradiate the ultraviolet light having a wavelength of, for example, 215 nm, the ultraviolet irradiation causes the irradiation. SO ₂ molecules in the sample gas are excited, and the excited SO ₂ molecules emit ultraviolet fluorescence to return to the ground state.

The intensity of the ultraviolet fluorescence emitted at this time depends on the excited SO ₂
Since it is proportional to the number of molecules, that is, the concentration of SO ₂ existing in the fluorescent chamber, it is possible to measure the SO ₂ concentration in the sample gas based on the detection result of the ultraviolet fluorescent by the fluorescent detector. Of.

[Problems to be solved by the invention]

By the way, in the ultraviolet fluorescence analyzer using the above-mentioned ultraviolet fluorescence method, in providing the cell with the light source light amount detector for the light amount monitor for increasing the measurement accuracy of the SO ₂ concentration, the light source light amount from the fluorescence chamber is used. It is extremely important to avoid the situation in which the light reflected by the cell portion up to the detector enters the fluorescent detector as stray light as much as possible. Therefore, conventionally, as shown in FIG. The inner surface of the cell portion 53A extending from the vicinity of the light chamber 51 to the fluorescent detector 52 is connected to the fluorescent detector 52.
The tapered surface is formed such that the diameter becomes smaller toward the side, and the reflected light is reduced as much as possible.

Reference numeral 54 in the figure is an L-shaped light shield, which is an ultraviolet light source 55.
In order to prevent the light from the above from directly entering the fluorescence detector 52 as stray light, it is provided at the fluorescence entrance portion e of the fluorescence chamber 51 to the fluorescence detector 52.

According to the above configuration, since the inner surface of the cell portion 53A is a tapered surface, the incidence of stray light on the fluorescence detector 52 is effectively suppressed, and therefore highly accurate measurement of SO ₂ concentration can be achieved. However, there is a drawback in that it has various problems in terms of manufacturability.

That is, as is clear from a glance at the structure of the cell 53 shown in FIG. 5, if the inner surface of the cell portion 53A is tapered, for example, when the cell 53 is manufactured by casting, the cell 53 may be removed due to casting. It becomes impossible to integrally cast
The cell portion 53A and the rest of the cell body portion 53B have to be cast separately, which increases the number of cast-molded parts, which increases the cost of manufacturing and processing and assembly. However, there was a drawback that extra work such as leak inspection of the joint of 53B was increased.

An object of the present invention is to provide an ultraviolet fluorescence analyzer, which has the same performance as that of the conventional structure by a simple improvement, and enables inexpensive casting by integrally casting a cell.

[Means for solving problems]

In order to achieve the above object, the present invention is an ultraviolet fluorescence analyzer by the ultraviolet fluorescence method described at the beginning, in which the inner surface of the cell portion from the vicinity of the fluorescence chamber to the light source light amount detector is formed into a straight surface. In addition, a cylindrical light-shielding body for preventing stray light from entering the fluorescence detector is connected to the fluorescence inlet portion of the fluorescence chamber for the fluorescence detector.

[Action]

According to the above characteristic configuration, since the inner surface of the cell portion from the vicinity of the fluorescent chamber to the light source light amount detector is a straight surface that can be easily cast, it is possible to integrally cast and mold the cell.

Then, if the inner surface of the cell portion is straightened, this becomes a factor of increasing the amount of stray light incident on the fluorescence detector.
Since a cylindrical light-shielding member is attached to the fluorescence inlet of the fluorescence chamber for the fluorescence detector, stray light is prevented from entering the fluorescence detector.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section of an ultraviolet fluorescence analyzer.
Is a cast cell made of aluminum whose inner surface is painted black by means of electrodeposition coating. The inner surface is a straight tubular portion 2 having flanges 2a and 2b connected at both ends, and the axis P ₂ is The first and second concentric members that are orthogonal to the axis P ₁ of the tubular portion 2
Cylindrical bodies 3 and 4 are integrally provided to form a fluorescent chamber 5 around the intersection P of both shaft cores P ₁ and P _{2 and at} the same time, close to the intersection P (specifically, the shaft core It is a position on P ₁ and a little away from the intersection P to the flange 2b side, but it may be a position on the intersection P or a little away from the intersection P to the flange 2a side). Holder 7 for optical lens 6
Are continuously provided on one end side of the tubular portion 2 and in the vicinity of the fluorescent chamber 5.

Reference numeral 8 denotes, for example, an ultraviolet irradiation light source that irradiates ultraviolet rays having a wavelength of about 215 nm. Rotated chopper
215 nm emitted from the ultraviolet irradiation light source 8 by the rotation of the chopper 10.
By intermittently irradiating the sample gas introduced into the fluorescence chamber 5 with ultraviolet light having a wavelength in the vicinity, the output from the detector can be converted into an alternating current and the background of the detector can be corrected.

It should be noted that a rod-shaped zinc lamp is used as the ultraviolet irradiation light source 8, and a light source slit a for irradiating ultraviolet rays from the light source 8 toward the condenser lens 6 is conventionally a circle having a diameter of about a lamp. In this embodiment, as shown in FIG. 2, the slit structure of the hole is used, but as shown in FIG. 2, the slit structure of the long hole is set so that the minor diameter is slightly shorter than the lamp diameter, and the amount of light from the light source incident on the fluorescence chamber 5 is increased. I am trying to

Reference numeral 11 denotes a light source light amount detector composed of a photodiode or a photoelectric tube for monitoring the light amount of the light source 8. The holder 12 of the light source light amount detector 11 is attached to the flange 2b on the other end side of the tubular portion 2. There is.

Reference numeral 13 denotes a fluorescence detector, the holder 14 of which is attached to the flange 3a of the first cylindrical body 3, and an O-ring 15 is provided in the path from the fluorescence chamber 5 to the fluorescence detector 13. Is provided with a colored glass filter 16 and a condenser lens 17, which detect the amount of ultraviolet fluorescent light emitted from SO ₂ molecules in the fluorescent chamber 5, and based on the detected fluorescent amount. Then, the SO ₂ concentration in the sample gas is measured.

Reference numeral 18 denotes a lid that closes the opening of the second tubular body 4. The lid 13 and the second tubular body 4 form a concave portion A for attenuating stray light, and the lid 18 has Is provided with a concave mirror 19, and among the fluorescence generated in all directions in the fluorescence chamber 5, the fluorescence directed toward the concave portion A for stray light attenuation on the side opposite to the fluorescence detector 13 is It is designed so as to increase the amount of fluorescent signal which is reflected toward the fluorescent detector 13 and is incident on the fluorescent detector.

Reference numeral 20 denotes a cylindrical light shield for preventing stray light from entering the fluorescence detector 13 so that the free end of the light shield does not block the light flux that has passed through the condenser lens 6 emitted from the ultraviolet light source 8. In addition, it is connected to the fluorescent light inlet 13b of the fluorescent chamber 5 to the fluorescent light detector 13.

Reference numeral 21 is a heater for heating the fluorescent chamber 5, 22 is a sample gas inlet, and 23 is a sample gas outlet.

In addition, except for the condenser lens 6, the light source light amount detector 11, the colored glass filter 16 and the concave mirror 19, the various holders 9,
All of the analyzer components that come in contact with the sample gas, such as 12, 14 and lid 18, cylindrical light-shielding body 20, are electrodeposition coated, black alumite,
It is painted black by means of black Teflon (trade name; DuPont) coating.

According to the ultraviolet fluorescence analyzer having the above structure, ultraviolet rays are emitted from the ultraviolet ray irradiation light source 8 toward the fluorescence chamber 5 through the light source slit a, and the light amount of the light source 8 is monitored by the detector 11. The light source intensity is calibrated.

Then, the SO ₂ molecule in the sample gas excited by the irradiation of the ultraviolet rays returns to the ground state, at this time, the fluorescence is emitted from the SO ₂ molecule, and a part of the fluorescence is directly detected by the fluorescence detector.
The fluorescent light which is incident on the stray light 13 and is directed to the concave portion A for attenuating the stray light is reflected by the concave mirror 19 toward the fluorescent detector 13 side, that is, the amount of the fluorescent signal is increased and the fluorescent light is incident on the fluorescent detector 13. The fluorescent detector 13 is highly sensitive to SO ₂
The concentration is measured.

By the way, as described above, when the inner surface of the cell portion 1A from the fluorescence chamber 5 to the fluorescence detector 13 is formed as a straight surface, the light from the ultraviolet irradiation light source 8 is reflected by the cell portion 1A of the straight surface. As compared with the conventional tapered surface structure, there is a problem in that the amount of stray light incident on the fluorescence detector 13 increases.

However, as shown in FIG. 5, there is a conventional L-shaped plate-shaped light-shielding body for light-shielding measures against stray light from the ultraviolet irradiation light source 55.
In place of 54, this is made into a cylindrical light-shielding body 20, and the cylindrical light-shielding body 20 is provided at the fluorescence inlet portion b of the fluorescence chamber 5 to the fluorescence detector 13, whereby the cell portion Fluorescence detector from 1A
The stray light incident on 13 can be effectively suppressed.

3 and 4 show another embodiment of the tubular light shield 20. What is shown in FIG. 3 is such that the free end c of the cylindrical light shield 20 can be brought as close as possible to the light beam within a range in which the light beam emitted from the ultraviolet ray irradiation light source 8 and transmitted through the condenser lens 6 is not blocked. To
The edge portion c of the free end is formed into a curved edge.
In the drawing, the free end of the cylindrical light shield 20 is extended to the side of the recess A for stray light attenuation, and the cylindrical light shield 20 is formed with a transmission hole d for transmitting the light beam. In each case, the surface portion in contact with the sample gas is painted black.

[Effect of device]

As described above, according to the present invention, the inner surface of the cell portion from the vicinity of the fluorescent chamber to the light source light amount detector is formed into a straight surface, and the entire cell can be integrally cast. No need for assembly and leak inspection work
It has become possible to greatly reduce the cell manufacturing cost compared to the conventional method.

Then, if the above-mentioned straight surface configuration is adopted, there is a concern that the amount of stray light incident on the fluorescence detector may increase, but instead of the conventional L-shaped plate-shaped light shield, this is formed into a cylindrical light shield. By doing so, it is possible to effectively prevent the stray light from entering the fluorescence detector,
As a whole, an ultraviolet fluorescence analyzer capable of exhibiting the same performance as the conventional one can be provided at a low cost with a simple structure.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultraviolet fluorescence analyzer showing an embodiment of the present invention, FIG. 2 is a detailed view of a light source slit, FIGS. 3 and 4
Each of the drawings is a perspective view showing another embodiment of the tubular light shield. And, FIG. 5 is a cross-sectional view of a conventional ultraviolet fluorescence analyzer. 1 ... cell, 1A ... cell part, 5 ... fluorescence chamber, 8 ... ultraviolet light source, 11 ... light source light intensity detector, 13 ... fluorescence detector, 20 ... cylindrical light shield, A ...... Recessed part for attenuating stray light.

Claims (1)

[Scope of utility model registration request] 1. An ultraviolet irradiation light source and a light source light amount detector for monitoring the light amount of the light source are arranged inside the cells at positions corresponding to each other across the fluorescent chamber, and further, from the light source to the light source. In a direction perpendicular to the optical path leading to the light amount detector and at positions corresponding to each other across the fluorescent chamber, in the ultraviolet fluorescence analyzer comprising a fluorescence detector and a recessed portion for stray light attenuation, The inner surface of the cell portion from the vicinity of the fluorescence chamber to the light source light amount detector is formed into a straight cylindrical surface, and a cylindrical light shield for preventing stray light from entering the fluorescent light detector is used. An ultraviolet fluorescence analyzer characterized in that it is connected to a fluorescence inlet of the chamber for the fluorescence detector.