JPS6361143A - System for measuring gas concentration distribution - Google Patents

Abstract

PURPOSE:To instantaneously measure gas concn. distribution without disturbing the gas distribution state of a measuring system, by constituting the measuring system of an irradiation system, a light receiving system, a gas concn. measuring cell and a spectroscopic means. CONSTITUTION:An irradiation system 1 consists of a light source 5 and light irradiating optical fiber 6 and a light receiving system 4 is constituted of a light receiving optical fiber 7 and a light receiver 8. A spectroscopic means 2 is constituted so as to make it possible to rotate a chopper 12, which has a filter 10 permitting the transmission only of the absorption wavelength of the specific gas in a flow passage 9 at one end thereof and a filter 11 not substantially absorbing the wavelengths of all of gaseous components in the flow passage 9 at the other end thereof, by a motor 13. Further, a gas concn. measuring cell 3 is constituted so that the end surface of an optical fiber 6 and that of an optical fiber 7 are arranged and fixed in opposed relationship by a gas permeable sintered filter and irradiation light is efficiently used in measurement. A semiconductor detector for detecting infrared rays is used in the light receiver 8 to compare and detect the intensities of lights propagated having two kinds of wavelengths and the intensity ratio thereof is converted to concn. by an operation part.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to a gas concentration distribution measuring system.

More specifically, the present invention relates to a system that measures the concentration distribution of a specific gas in a gas flow path using an analyzer that utilizes infrared or ultraviolet absorption by gas.

(B) Prior Art Conventionally, when measuring the concentration distribution of a specific gas in a gas flow path such as a flue, one or more analyzers are used, or one A method is used in which the concentration is measured sequentially by sampling at multiple points and switching samples using an analyzer on one side.As shown in Figure 4, the analyzer used above has a light source (24) on one side and a a translucent measuring cell (26) with a detector (25) on the side, and a light beam interposed in the optical path between the source and the translucent measuring cell or between the measuring cell and the detector; Transmissive filters (27) that selectively transmit light at the absorption wavelength of a specific gas component in the gas to be measured and light at a non-absorption wavelength that is not absorbed by any gas component in the gas to be measured can be rotated by a motor (28). For the measurement, for example, as shown in FIG. ), the sample gas at the measurement position is sucked into the measurement cell of the analyzer, and the light from the light source is directly irradiated from one of the cells, and the gas is emitted from the other cell. The light beam selectively transmitted by the optical tapping means is selectively transmitted and detected by a detector, or the light from the light source is first selectively transmitted by the optical tapping means, and the light is directly irradiated from one of the cells and emitted from the other cell. The light emitted was detected by a detector.

(c) Problems to be Solved by the Invention However, in the conventional analyzer described above, the sample gas is sucked in by a pump and flows into the measurement cell, which causes a delay in the sample and makes it impossible to measure instantaneous changes. Disturbances occur in the gas distribution in the measurement system.If the sample is small, there will be an additional delay due to the small amount of sample.
Simultaneous measurement using several analyzers is expensive; multi-point sampling has a delay due to sample switching, making continuous measurement impossible, making it impossible to capture rapid changes in the distribution; pressure (negative pressure) in the sampling measurement system; There are problems such as the need to adjust the sampling by adjusting the pressure (or positive pressure).

The present invention has been made in view of this situation, and particularly aims to provide a gas concentration distribution measuring system that can instantaneously measure gas concentration distribution without disturbing the gas distribution state of the measurement system.

(d) Means for Solving the Problems Thus, according to the present invention, a plurality of light irradiation optical fibers each having a distal end inserted into the gas flow path to be measured and a rear end of these light irradiation optical fibers are provided. an irradiation system consisting of an external optical path capable of supplying light from the outside to the end; and a plurality of light receiving lights whose tips are respectively inserted into the gas flow path to be measured corresponding to each of the light irradiation optical fibers. A light receiving system consisting of a fiber and a light receiver capable of detecting the intensity of light traveling through these light receiving optical fibers outside the gas flow path to be measured, and each of the above-mentioned corresponding light irradiation optical fibers and light receiving optical fibers. a gas-permeable fixing member that fixes the tip portions so that the tip surfaces thereof face each other at predetermined optical path length intervals; A gas concentration distribution measuring system is provided which includes a spectroscopy means that can be selectively arranged with a transmissive filter and a transmissive filter having a wavelength that is not substantially absorbed by any gas component in the gas to be measured.

The joint between the irradiation system and the light receiving system in the system of the second invention consists of a light emitting optical fiber tip surface, a light receiving optical fiber tip surface, and a gas that fixes these tip surfaces so that they face each other at a predetermined optical path length interval. and a transparent fixing member, in which the light from the tip surface of the optical fiber for light irradiation is not dispersed but is irradiated with parallel rays and is condensed at the tip surface of the optical fiber for light reception. This is preferable in that the light irradiated onto the object is used effectively, and for example, a configuration in which a convex lens is used on each of the above-mentioned tip surfaces is exemplified. Further, as the gas-permeable fixing member, sintered metal, vapor, glass wool, or a combination thereof is suitable. The predetermined optical path length is set between 1 and 300+u+ depending on the measured gas concentration.

The external optical path of the irradiation system used in this invention may be composed only of a light source, and each end of the light source and the light of the light source can be supplied to each end of a plurality of light irradiation optical fibers. and a light supply optical path set corresponding to the section.

Preferably, the optical path is formed by an optical fiber.

The spectroscopic means used in this invention may be set either in the optical path of the irradiation system or in the optical path of the light receiving system.

The above-mentioned spectroscopic means is configured to be able to switch between a filter that transmits the absorption wavelength of the gas component to be measured and a filter that transmits the wavelength that is not substantially absorbed by any of the gas components in the gas to be measured. For example, the above two types of filters may be attached to a motor, and the filter may be configured to cross the optical path intermittently (chopping) as the motor rotates. As an example of a configuration in which the spectroscopic means is set in the optical path, the filter may be configured to cross all of a plurality of optical paths at the same time, or it may be configured to cross each optical path sequentially. You can. The former configuration includes a configuration in which a plurality of optical fibers for light irradiation are bundled together, and the latter includes a configuration in which a plurality of optical fibers for light irradiation are arranged so that the ends of the optical fibers for light irradiation are lined up on the rotation path of the filter. One example is a structure in which an optical fiber is provided. In the former case, it is preferable that the number of light receivers used for detection be prepared in accordance with the number of light-receiving optical fibers and connected to the end of each light-receiving optical fiber. On the other hand, in the latter case, the number of light receivers used for detection may be one, or the number may correspond to the number of light receiving optical fibers used. When configured with one light receiver, a plurality of optical fibers for light reception are bundled near the light receiver, their ends are connected to the light receiver, and a timing element or the like is provided to discriminate the light rays that are sequentially chopped by the spectrometer. It is preferable to have a configuration including the following.

Note that when using ultraviolet rays as a light source, a quartz fiber is suitable as the optical fiber, and when using infrared rays, fluoride fibers, chalcogen glass fibers, etc. are suitable.

(P) Effect According to this invention, the irradiation light traveling through the irradiation system is introduced directly into the gas flow path to be measured through the optical fiber, is emitted from the end of the optical fiber, and is transmitted through the gas atmosphere. The light is focused on the ends of light-receiving optical fibers placed opposite each other, and propagated through the light-receiving system to the light receiver.

The absorption wavelength of only the specific component gas and the wavelength that is not substantially absorbed by any of the gases in the gas to be measured are alternately propagated to the photodetector before or after passing through the gas atmosphere. By comparing the intensities of these lights, the concentration of the specific component gas is detected.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereby.

(F) Embodiment FIG. 1 is an explanatory diagram of the configuration of an embodiment of an apparatus illustrating the system of the present invention. This example is configured so that measurements can be made at any four points within the gas flow path to be measured. In the figure, (1) is an irradiation system, (2) is a spectroscopic means, (3) is a gas concentration measuring cell, and (4) is a light receiving system. Irradiation system (1)
consists of a light source (5) and an optical fiber for light irradiation (6),
The light receiving system (4) includes a light receiving optical fiber (7) and a light receiver (8).
It consists of (9) is a gas flow path to be measured.

A halogen lamp is used as the light source (5). The spectroscopic means (2) includes a filter (4,
a 2μ bandpass filter (ill) and a filter having a wavelength that does not substantially absorb any of the gas components in the flow path (9) (3.2μ bandpass filter) (11); 12) to the motor (13
) so that it can be rotated. In addition, the gas concentration measuring cell (3) is connected to the end face (1) of the optical fiber (6) for light irradiation using a gas-permeable sintered filter (14) as shown in
5) and the end face of the light-receiving optical fiber (7) (work 6) are arranged and fixed facing each other, and the end face of the light-irradiating optical fiber (15) is fixed so as to face each other.
) A convex lens for light irradiation (17) is set so that light can be emitted from the end face (15) in substantially parallel rays, and a convex lens for light irradiation (17) is set near the opposing optical fiber end face for light reception (16) to condense the parallel irradiated light rays. A convex condensing lens (18) that emits light is provided. Due to these, the irradiation light traveling through the light irradiation optical fiber can be efficiently used for measurement. Moreover, a semiconductor detector (pyroelectric detector) for detecting infrared rays is used in the light receiver (8), and the 2
Comparatively detect the intensity of light at different wavelengths.

These detected intensity ratios are converted into concentration by a calculation unit (not shown) connected to the light receiver.

Next, the operation of this device will be explained.

Light from a light source is selectively transmitted by a spectroscopic means into two wavelengths: one that is absorbed by a specific gas component in the gas to be measured and a wavelength that is not substantially absorbed by any of the gas components in the gas to be measured. Transmitted light of different wavelengths simultaneously travels through four light irradiation optical fibers and is alternately irradiated from the end face of the light irradiation optical fibers of the measurement cell. The alternately irradiated two wavelengths of light are transmitted through the gas atmosphere filling the cell alternately as substantially parallel rays by a convex lens for light irradiation, and are respectively focused by a condensing lens and placed facing each other. The light is alternately propagated to the end face of the light-receiving optical fiber.

The propagated light of two different wavelengths travels through a light-receiving optical fiber and is alternately received by a light receiver, and from the intensity ratio of these two wavelengths, a specific component of the gas components filled in the measurement cell is determined. The concentration will be detected.

In addition, in Fig. 1, four optical fibers for light irradiation (6) are bundled up to the front of the gas flow path to be measured, and the four optical fibers for light irradiation (6) are simultaneously connected to each other by the spectrometer (2). The configuration shown above is configured to split and transmit light from a light source.
It is also possible to construct a structure in which the light beams are sequentially separated and transmitted to the optical fiber (6) for irradiating the light of the book, and these separated light beams are received by one light receiver. An explanatory diagram of the configuration of this example is shown in FIG. In this figure, the irradiation system (20) is composed of a light source (21) and four separated light irradiation optical fibers (22), and the spectroscopic means (23) set at the above-mentioned separation position is the same as above. In addition to the timing element (24
), and is the same as that shown in FIG. 1 except that the ends of the light-receiving optical fibers are bundled and connected to one light receiver. The four optical fibers for light irradiation are arranged so that each cross section is on a rotating circumferential path drawn by rotation of the filter of the spectroscopic means.

In this configuration, the operation is as follows: The spectroscopic means sequentially travels through the four light irradiation optical fibers, and the spectral transmitted light that sequentially travels to the light receiver is discriminated and processed by a timing element set in the spectroscopic means. This is done in the same way as above.

(G) Effects of the Invention According to the present invention, the gas concentration distribution within the gas flow path to be measured can be measured without disturbing the gas atmosphere within the gas flow path. Additionally, since there is no need for sampling, the measurement system can accurately follow rapid changes.

Furthermore, it is a highly reliable measurement system that can measure changes in the state of the gas flow path as it is, regardless of the pressure within the gas flow path. Furthermore, it is possible to provide a measurement system that is cheaper than conventional ones. Furthermore, since the gas in the gas flow path to be measured is not sampled outside the system, even dangerous gases can be measured in a state that is safe for the human body.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the system of the present invention;
FIG. 2 is an explanatory diagram of the configuration of an example of a gas concentration measurement cell used in the system of FIG. FIG. 5 is a diagram illustrating the configuration of an apparatus for measuring gas concentration distribution using a conventional gas concentration analyzer. (1)(20)...-Irradiation system, (2)(23
)... Spectroscopic means, (3)... Gas concentration measuring cell, (4)... Light receiving system, (5)...
...Light source, (6) (22) ... Optical fiber for light irradiation, (7
)... Optical fiber for light reception, (8)...
Light receiver, (9)...Measurement gas flow path,
(10) (II)... Filter, (12)...
...Chopper, (13) ...Motor,
(14)...Filter after sintering, (17)
... Convex lens for light irradiation, (18) ... Condensing lens, (24) Timing element.

Claims (1)

[Scope of Claims] 1. A plurality of optical fibers for light irradiation each having a distal end inserted into the gas flow path to be measured, and an external device capable of supplying light from the outside to the rear ends of these optical fibers for light irradiation. an irradiation system consisting of an optical path; a plurality of light-receiving optical fibers whose tips are respectively inserted into the gas flow path to be measured corresponding to each of the light-irradiating optical fibers; A light receiving system consisting of a light receiver capable of detecting the intensity of the light to be measured outside the gas flow path to be measured, and a tip surface of each of the corresponding light irradiation optical fibers and light receiving optical fibers arranged at predetermined optical path length intervals. a gas-permeable fixing member whose tips are fixed so as to face each other; a transparent filter having an absorption wavelength of the gas component to be measured; A gas concentration distribution measuring system comprising a spectroscopic means that can be selectively arranged with transmitting filters having wavelengths that are not substantially absorbed by gas components.