JP3301049B2 - Gas analyzer using ultraviolet fluorescence analysis - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas analyzer for measuring, for example, the concentration of SO ₂ (sulfur oxide) in the atmosphere using an ultraviolet fluorescence analysis method (hereinafter referred to as an ultraviolet fluorescence method). It is.

[0002]

_2. Description of the Related Art One of the methods for analyzing SO ₂ is an ultraviolet fluorescence method. In the ultraviolet fluorescence method, when a sample gas is irradiated with ultraviolet light, SO ₂ contained in the sample gas emits ultraviolet light, and the intensity of the ultraviolet light is measured to measure the SO ₂ concentration. It was made.

FIG. 4 shows an ultraviolet fluorescence analyzer using the ultraviolet fluorescence method. In FIG. 4, when the sample gas S introduced into the cell 40 is irradiated with ultraviolet rays having a wavelength of about 215 nm emitted from the ultraviolet light source 41, SO ₂ contained in the sample gas S from near the focal position of the condenser lens 42. The molecules emit ultraviolet fluorescent light, and the amount of the ultraviolet fluorescent light is detected by a fluorescent detector (for example, a photomultiplier) (hereinafter, referred to as PMT) 43 provided at a position orthogonal to the optical axis of the condenser lens 41. The SO ₂ concentration in the sample gas S is measured based on the detected light amount. In FIG. 4, reference numerals 44 and 45 denote an excitation wavelength selection filter and a fluorescence selection filter, respectively, and reference numeral 46 denotes a condenser lens for ultraviolet fluorescence.

[0004]

However, the fluorescence detector 4
In the sensitivity of No. 3, drift due to background (stray light) occurred, and a pointing error due to temperature fluctuation, deterioration of the light source 41, etc. was large.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultraviolet fluorescence analysis method capable of reducing pointing errors due to background (stray light) drift, temperature effects, and the like. An object of the present invention is to provide a gas analyzer used.

[0006]

In order to achieve the above object, a gas analyzer using an ultraviolet fluorescence analysis method according to the present invention comprises a holding member having a black inner surface and an ultraviolet light source and a first light source.
A condensing lens is provided, and an attachment member is movably provided inside the holding member. The attachment member is detachably attached to the attachment member, and the position of the attachment member is adjustable to a position where the first condenser lens collects ultraviolet light. A micro-cell made of a transparent fluorescent material is provided, and a second condensing lens and a fluorescence detector are provided on the holding member at a position orthogonal to the optical axis of the first condensing lens. In a state where the gas and the reference gas are alternately introduced at a constant cycle, ultraviolet light from the ultraviolet irradiation light source is irradiated to the microcell via the first condenser lens, and then emitted from the sample gas. The emitted ultraviolet fluorescence is made to enter the fluorescence detector via the second condenser lens.

[0007]

The output from the fluorescence detector can be exchanged by alternately introducing the sample gas and the reference gas into the minute cell at a constant period. That is, since only the difference between the physical quantities based on the sample gas and the reference gas is extracted as an AC signal, a very stable signal without drift due to the background (stray light) can be obtained, and an indication error due to temperature influence or the like can be obtained. Can be reduced.

In introducing gas into the cell,
When the above-mentioned fluid modulation method is adopted, it is necessary to reduce the cell capacity as compared with the case where the fluid modulation method is not adopted, in order to suppress large consumption of gas. Therefore, in the present invention, by adopting a small cell having a small sample gas introduction amount as the cell, the amount of ultraviolet fluorescence emitted from the inside of the minute cell is reduced, but the ultraviolet light emitted from the ultraviolet irradiation light source is emitted into the minute cell. The holding member has a focusing lens that focuses light on the sample and a focusing lens that focuses ultraviolet light emitted from the sample gas on the fluorescence detector. It can be collected on a fluorescence detector.

Further, since the microcell is processed into a box shape using an ultraviolet or ultraviolet fluorescent material such as quartz glass, for example, a tolerance (dimensional error) occurs with respect to a target dimension, but the microcell is retained. Since the position can be adjusted with respect to the member, even a minute cell having a large tolerance can be easily positioned.

Furthermore, even when performing fluid modulation, the use of the microcell of the present invention enables the modulation with a small amount of gas, as compared with the case of using a cell having a large cell capacity. The switching efficiency between the sample gas and the reference gas can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited thereby.

1 and 2, reference numeral 1 denotes a rectangular box shape, the longitudinal direction of which is set along the optical axis A of the condenser lens 2, and whose inner surface is painted black by means of electrodeposition coating. The holding member 1 is provided with an ultraviolet light source 3 and a condenser lens (hereinafter, referred to as a first condenser lens) along an ultraviolet irradiation direction (the direction of the arrow indicated by B). 2. A fluorescence detector (referred to as “2”) in which an excitation wavelength selection filter 4 and a minute cell 5 described later are sequentially arranged optically and provided at a position orthogonal to the optical axis A of the first condenser lens 2. For example, the PMT 6 is also arranged on the holding member 1. Reference numerals 7 and 8 denote a filter for fluorescence selection disposed on the holding member 1 between the fluorescence detector 6 and the microcell 5, and the sample gas S introduced into the microcell 5, respectively.
(Hereinafter, referred to as a second condenser lens).

Further, the minute cell 5 is processed into a rectangular box shape using an ultraviolet and ultraviolet fluorescent transmitting material such as quartz glass. Then, the focus position F of the ultraviolet light on the holding member 1
The micro cell 5 can be inserted into and detached from the attachment member 9 attached to the base member.

That is, as shown in FIG. 3, the microcell 5 is composed of a fluorescent chamber 10 formed at one end, a gas introduction pipe 12 communicating with the fluorescent chamber 10 via a pipe connection section 11, and a gas introducing pipe. The mounting member 9 has a size capable of inserting the fluorescent chamber 10 and the pipe connection portion 11 of the microcell 5 while the outlet pipe 13 and the flange-shaped pipe mounting lid 14 formed at the other end are formed. And a flange portion 9b formed at one end of the frame 9a. The mounting member 9 includes a pair of holders 16, 16 provided above and below a notch (not shown) formed along the optical axis A of the first condenser lens 2 on one side surface 1 a of the holding member 1. Thereby, the position can be adjusted in the direction of the optical axis A and in the vertical direction.

For example, the rails 1 of the holders 16, 16 fixed to the side surface 1a around the notch by screws 17
Attaching the mounting member 9 along the rails 16a, 1
6a, the mounting member 9 can be moved in the direction of the optical axis A within the minute length range, and the mounting members 9 are formed in the holders 16, 16 by the elongated holes 16b formed vertically long. It can move up and down within the range.

Therefore, the microcell 5 is inserted from the fluorescent chamber 10 into the insertion passage 15 of the mounting member 9, and the microcell 5 is further inserted until the pipe mounting cover 14 comes into contact with the frame 9 b of the mounting member 9. Just by inserting, the position of the micro cell 5 in the direction of the optical axis A and the vertical direction can be adjusted. And the micro cell 5
Is inserted until it comes into surface contact as described above, the fluorescent chamber 10 of the microcell 5 is positioned on the optical axis A of the first condenser lens 2,
In addition, the length of the fluorescent chamber 10 and the length of the pipe connection portion 11 are set in advance so as to be located at the focus position F of the ultraviolet light. The positional deviation can be adjusted only by finely adjusting the insertion length of the microcell 5.

In this embodiment, the flow path switching means 18
Thus, the sample gas S and the reference gas (for example, zero gas) R are alternately introduced into the micro cell 5 at a constant period and a constant amount.

As described above, in the present embodiment, the gas is introduced into the minute cell 5 by using the fluid modulation method. Therefore, the difference between the signals based on the sample gas S and the reference gas R is used as the SO ₂ signal. By performing the processing, it is possible to reduce a pointing error due to drift of the background (stray light), temperature fluctuation, deterioration of the light source 3, and the like.

Further, since the minute cell 5 is used, modulation can be performed even with a small amount of gas, and the switching efficiency between the sample gas S and the reference gas R can be improved.

Further, in this embodiment, the fluorescence detector 6 detects ultraviolet fluorescence as efficiently as possible while using the microcell 5.
And a first condenser lens 2 for condensing the ultraviolet rays emitted from the ultraviolet irradiation light source 3 into the microcells 5 so that the ultraviolet rays emitted from the sample gas S can be condensed on the fluorescence detector 6. Consideration has been given to providing a second condensing lens 7 to the holding member 1.

Moreover, since the holding member 1 is provided with the mounting member 9 into which the micro cell 5 can be inserted, the position of the micro cell 5 in the direction of the optical axis A and the vertical direction can be adjusted, and the position of the micro cell 5 in the insertion direction can be adjusted. Therefore, the ultraviolet light emitted from the ultraviolet irradiation light source 3 can always be collected in the microcell 5, and the intensity of the ultraviolet fluorescence can be measured with high sensitivity.

In the present embodiment, the gas introducing pipe and the gas deriving pipe are both arranged on the same side (lid side) as the minute cells. The piping for each may be arranged on the opposite side via the fluorescent chamber. In this case, it is necessary to provide mounting members for adjusting the position into which the microcells are inserted, on both sides of the holding member in the same configuration, and to provide a pair of microcell lids, and to the microcell holding member. At the time of attachment / detachment or position adjustment in three directions, it is necessary to remove one lid of the micro cell.

In this embodiment, a square box-shaped holding member is shown. However, a cylindrical holding member may be used. The shape is arbitrary, and the shape of the minute cell is not limited to a square but may be a box. Is optional.

[0024]

As described above, according to the present invention, the fluid modulation system in which the sample gas and the reference gas are alternately introduced at a constant period is employed, so that an extremely stable signal without drift due to background (stray light) can be obtained. In addition to this, it is possible to reduce the pointing error due to the influence of temperature and the like.

Further, a first condenser lens for condensing the ultraviolet rays emitted from the ultraviolet irradiation light source in the minute cell, and a second condenser lens for condensing the ultraviolet fluorescence emitted from the sample gas to the fluorescence detector.
By providing the condenser lens on the holding member, it is possible to collect ultraviolet fluorescent light in the fluorescent light detector as efficiently as possible while using a micro cell.

Further, although a minute cell has a tolerance (dimension error) with respect to the size of the processing target, the minute cell can be arranged so as to be adjustable in position with respect to the holding member. Positioning is possible, so that ultraviolet rays emitted from the ultraviolet irradiation light source can always be collected in the microcell, and the intensity of ultraviolet fluorescence can be measured with high sensitivity.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the overall configuration showing an embodiment of the present invention.

FIG. 2 is a schematic configuration explanatory view showing the above embodiment.

FIG. 3 is an explanatory diagram of a main part configuration showing the embodiment.

FIG. 4 is an explanatory view of the entire configuration showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Holding member, 2 ... 1st condensing lens, 3 ... Ultraviolet irradiation light source, 5 ... Box-shaped minute cell, 6 ... Fluorescence detector, 8 ... 2nd condensing lens, 9 ... Mounting member, S ... Sample Gas, R: Reference gas.

Continuation of the front page (56) References JP-A-63-222242 (JP, A) JP-A-51-54487 (JP, A) JP-A-62-259043 (JP, A) , U) JitsuHiraku flat 5-71757 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) G01N 21/00 - 21/74 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. An ultraviolet irradiation light source and a first condenser lens are provided on a holding member having a black inner surface, and a mounting member is movably provided inside the holding member. position adjustable to the condensing position of the UV by the condenser lens, provided with a micro cell consisting of ultraviolet and ultraviolet fluorescent transparent material, the in a position perpendicular to the optical axis of the first condensing lens of the holding member 2 A condenser lens and a fluorescence detector are provided, and the sample gas and the reference gas are alternately introduced into the microcell at a constant period, and the ultraviolet light from the ultraviolet irradiation light source is supplied to the first condenser lens. Irradiating the microcell via
A gas analyzer using ultraviolet fluorescence analysis, wherein ultraviolet fluorescence emitted from the sample gas at that time is incident on the fluorescence detector through the second condenser lens.