JPH11183386A - Gas analyer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy by reducing and restraining generation of stray light by providing an optical trap for absorbing and reducing condensed ultraviolet rays. SOLUTION: An SO analyzer is provided with an optical trap 4 for reducing stray light. The optical trap 4 has the surface painted black so that when ultraviolet rays are applied to the surface, they are absorbed and reflected by black painting and attenuated. The ultraviolet rays radiated from a light source 5 are condensed in the central part A of a cell 1, and ultraviolet fluorescence is generated by SO2 component contained in sample gas in its vicinity. The generation is detected by a photomultiplier 8 to find the concentration of SO2 . The ultraviolet rays condensed in the central part A reach the optical trap 4 while spreading so that the light intensity is attenuated to reduce and restrain the generation of stray light. Accordingly, the measurement accuracy can be stably improved to reduce influence of temperature upon the photomultiplier 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

A gas analyzer (hereinafter referred to as SO ₂ analyzer) for analyzing the SO ₂ with the present invention the UV fluorescent method. BACKGROUND OF THE INVENTION

[0002]

_2. Description of the Related Art SO ₂ analyzers using the ultraviolet fluorescence method are:
By irradiating the sample gas with ultraviolet light, ultraviolet fluorescence is generated by SO ₂ contained in the sample gas, and the intensity of the ultraviolet fluorescence is measured to obtain the concentration of SO _2. For example, it is configured as shown in FIG.

In FIG. 1, reference numeral a denotes a cell, b denotes an inlet of a sample gas, c denotes an outlet thereof, d denotes a light source for irradiating ultraviolet rays, e and f denote condenser lenses, and g denotes a photomultiplier. In particular, the ultraviolet rays emitted from the light source d are condensed by the converging lens e to generate the ultraviolet fluorescent light efficiently, and the ultraviolet rays are collected before the photomultiplier g to detect the fluorescent light efficiently. An optical lens f is provided.

[0004]

However, in the above-mentioned conventional SO ₂ analyzer, the ultraviolet light emitted from the light source d is condensed at the center of the cell a and then spreads while being spread at the other end of the cell a. The light is reflected by the wall surface h, becomes stray light, and a part thereof is detected by the photomultiplier g. If the amount of the stray light is large, noise is increased, and an error is largely reflected on a measurement value detected by the photomultiplier g which is easily affected by temperature. For this reason, the reliability and measurement accuracy of the SO ₂ analyzer may be reduced.

The present invention has been made in view of such circumstances,
SO using ultraviolet fluorescence method designed to reduce stray light
It aims to provide _two analyzers.

[0006]

According to the present invention, means for solving the above-mentioned problems are constituted as follows. That is, a light source for generating ultraviolet light is provided at one end side of the cell into which the sample gas is introduced, and the ultraviolet light emitted from the light source is condensed in the cell by a condenser lens,
In a gas analyzer using an ultraviolet fluorescent method, ultraviolet fluorescent light generated at a light condensing portion by SO ₂ component in the sample gas is detected by light detecting means provided on a side of the cell. An optical trap is provided inside the other end of the cell to absorb and reduce the ultraviolet light after condensing.

The optical trap absorbs and reduces ultraviolet light at the other end of the cell, attenuates its light intensity, and reduces stray light.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the SO ₂ analyzer of the present invention will be described below in detail with reference to the drawings. Figure 1 shows SO ₂
In the figure, reference numeral 1 denotes a cell, 2 denotes a sample gas inlet, 3 denotes an outlet thereof, 4 denotes an optical trap for reducing stray light, 5 denotes a light source for generating and irradiating ultraviolet rays, 6
Is a condenser lens composed of two convex lenses 61 and 62, 7 is a condenser lens composed of two convex lenses 71 and 72, and 8 is a light detecting means composed of a photomultiplier (photomultiplier).

The above-described optical trap 4 is formed in a conical shape as shown in FIG. 2, and its surface is coated with black paint. When the surface is irradiated with ultraviolet rays, it is reflected while being absorbed by the black paint. The light is attenuated in the course of time, whereby the light intensity is attenuated, and the generation of stray light can be reduced and suppressed.

With the above-described configuration, the ultraviolet light emitted from the light source 5 is collected at the central portion A of the cell 1, and ultraviolet fluorescence is generated in the vicinity of the central portion A by the SO ₂ component contained in the sample gas. This is detected by the photomultiplier 8 and the concentration of SO ₂ is determined. The ultraviolet light condensed at the central portion A of the photomultiplier 8 reaches the optical trap 4 while spreading, and the light intensity is attenuated as described above, and the stray light is reduced. The occurrence of
As a result, the measurement accuracy is stably improved, and the influence of the temperature of the photomultiplier 8 can be reduced.

In the present invention, the shape of the optical trap 4 is not limited to that shown in FIG. 2, but may be in any form as long as the intensity of the ultraviolet light can be attenuated.

[0012]

As described above, according to the gas analyzer of the present invention, the optical trap for absorbing and reducing the collected ultraviolet light is provided inside the cell, so that the generation of stray light is reduced and suppressed. The measurement accuracy can be stably improved, and the influence of the temperature change on the measurement accuracy can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a gas analyzer of the present invention.

FIG. 2 is a correspondence diagram of the condenser lens and an optical trap.

FIG. 3 is a configuration diagram showing an example of a conventional SO ₂ analyzer.

[Description of Signs] 1 ... cell, 4 ... optical trap, 5 ... light source, 6 (61, 6)
2) ... a condenser lens, 8 ... a light detecting means.

Claims (1)

[Claims] 1. A light source for generating ultraviolet light is provided at one end of a cell into which a sample gas is introduced, and ultraviolet light emitted from the light source is condensed in the cell by a condenser lens. In a gas analyzer using an ultraviolet fluorescent method, ultraviolet fluorescent light generated at a light condensing portion by the SO ₂ component is detected by light detecting means provided on the side of the cell. A gas analyzer, wherein an optical trap for absorbing and reducing ultraviolet light after focusing is provided inside the side.