JPH102894A - Hazardous gas detection agent and detection method - Google Patents

Abstract

(57) [Problem] To provide a detection agent suitable for detecting discoloration using a color mark sensor, and to provide a method capable of reliably detecting a harmful component gas using a color mark sensor. provide. SOLUTION: As a detection agent, a white particle having a particle size in the range of 1 to 4 mm and having a light transmittance of substantially 0 by a spectrophotometer is discolored by contact with a detection target gas. The color change is detected by a color mark sensor using a detecting agent carrying a color changing substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection agent and a detection method for harmful gases, and more particularly, to a detection agent having a carrier carrying a discoloration substance that changes color when it comes into contact with a harmful component as a detection target gas. The present invention relates to a method for detecting the presence of a harmful component gas by detecting color change of a detection agent by a color mark sensor.

[0002]

2. Description of the Related Art In semiconductor manufacturing plants, silicon, arsenic,
Volatile inorganic hydrides such as phosphorus and selenium, volatile inorganic hydrides obtained by substituting part or all of hydrogen of these volatile inorganic hydrides with halogen atoms, or alkyl or alkoxide groups Uses harmful gases such as substituted organometallic compounds. Therefore,
Before the exhaust gas containing these harmful gases is released into the atmosphere, measures have been taken to detoxify the exhaust gas by removing harmful components in the exhaust gas.

In recent years, as the detoxification treatment, a method has been known in which exhaust gas is circulated through an abatement cylinder filled with a solid abatement agent to adsorb harmful components to the abatement agent or decompose by the action of the abatement agent. Are often adopted. In the detoxification treatment using such a scavenger, in order to prevent harmful components from leaking due to breakthrough of the scrubber and drift of the gas flow in the scrubber, it is necessary to constantly ensure that the scrubbing is done. It is necessary to monitor and shut down the abatement cylinder or replace the abatement agent before the abatement cylinder loses the abatement capacity. For this reason, a detection agent for detecting the breakthrough period of the abatement agent is disposed downstream of the abatement agent.

As the above-mentioned detection agent, various substances are used depending on the type of gas to be detected. In general, substances which change color upon contact with the harmful components, for example, bismuth chloride, litmus, copper hydroxide and the like are used. Have been. In order to increase the contact efficiency between the gas and the detecting agent, these discoloring substances are usually used in the form of pellets of about 1 to 10 mm or used by being carried on a carrier such as silica gel or alumina which does not contribute to the discoloring reaction. I have.

[0005] The simplest method is to visually check the presence or absence of discoloration of the detection agent by providing a transparent window in a part of the cylinder filled with the detection agent.
There have been various difficulties such as inconvenience of constant monitoring by human beings, safety problems due to human errors and burden of labor costs.

For this reason, it has been proposed to automatically monitor the discoloration of the detecting agent by optically detecting the discoloring of the detecting agent with a color mark sensor (actually, 3-4).
No. 1779). This color mark sensor detects optical discoloration by irradiating light from a light emitting element to a detecting agent via an optical fiber, receiving reflected light from the detecting agent by another optical fiber, guiding the light to a light detecting element, and detecting light. The color change of the detecting agent is detected based on the light receiving intensity of the element.

[0007]

However, the detection of discoloration by the above-mentioned color mark sensor may differ in detection results due to variations in the distance between the detecting agent and the tip of the optical fiber. Could not. Further, in order to detect discoloration in a stable state with a color mark sensor, a detection agent whose brightness changes greatly due to discoloration must be used, and the types of detection agents that can be used are limited.

Accordingly, the present invention provides a detection agent suitable for detecting discoloration using a color mark sensor and a method for reliably detecting harmful component gases using a color mark sensor. It is intended to be.

[0009]

Means for Solving the Problems In order to achieve the above object, the detection agent of the present invention is a detection agent in which a color changing substance that changes color upon contact with a gas to be detected is carried on a carrier, wherein the carrier is It is characterized by being white particles having a particle size in the range of 1 to 4 mm, and having a light transmittance of substantially 0 by a spectrophotometer.

The method for detecting a harmful gas according to the present invention is a method for detecting a harmful gas by detecting color change of a detection agent by a color mark sensor having an optical fiber, wherein the detection agent has a particle size of 1 to 4 mm. In the range of the white particles, and, the light transmittance by a spectrophotometer is substantially zero, the carrier is characterized by using a detection agent carrying a discoloration substance that changes color by contact with the gas to be detected I have.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an example of an apparatus configuration for implementing a method for detecting a harmful gas by a color mark sensor using the detection agent of the present invention.

This apparatus includes a main abatement agent 4, a detection agent, and a main body, in order from the upstream side of the gas flow, inside a packed column (column) 3 having an inlet 1 for an exhaust gas containing harmful components and an outlet 2 for a processing gas. 5, a preliminary abatement agent 6 is filled in layers, and a detection window 7 made of a transparent material is provided on the peripheral wall of the filling cylinder 3 corresponding to the position where the detection agent 5 is filled.
The detection unit 9 is mounted so that harmful components can be removed by the main abatement agent 4 and monitoring of harmful components can be monitored by the detection agent 5 at the same time.

The color mark sensor 8 for detecting the color change of the detecting agent includes a detecting unit 10 having a built-in light emitting element and a light receiving element, and two optical fibers 12 on an irradiation side and a light receiving side held by an optical fiber fixture 11. 13, and the detection section 9 at the tip of the optical fibers 12, 13 is connected to the detection window 7 by a mounting bracket (not shown).
It is fixed in a state pressed against the outer surface of.

The color mark sensor 8 irradiates the light from the light source provided in the detection unit 10 to the detection agent 5 via the optical fiber 12 on the irradiation side, and receives the reflected light from the detection agent 5 on the light receiving side. The optical fiber 13 is configured to detect the change in intensity and color tone of the received light with a light detection element provided in the detection unit 10 to detect discoloration.

As described above, the detection agent used for detecting the color change of the detection agent using the color mark sensor includes:
A substance that changes color upon contact with a harmful component that is a gas to be detected, for example, a color changing substance such as bismuth chloride, litmus, copper hydroxide, cresol red, or bromophenol blue, has a particle size of 1 to 4 mm, preferably 2 to 3 mm. And a particle supported on an opaque carrier whose light transmittance by a spectrophotometer is substantially 0 is used.

If the particle size of the carrier is less than 1 mm, the carrier tends to be scattered along with the gas flow, and if it exceeds 4 mm, the distance between the detecting portion at the tip of the optical fiber and the detecting agent varies. It is difficult to confirm stable discoloration.

Further, by using a white carrier having a light transmittance of substantially 0, almost the entire amount of light irradiated on the detecting agent 5 from the optical fiber 12 can be reflected on the surface of the carrier. It is possible to reliably detect the discoloration of the discoloration substance carried on the substrate. On the other hand, if the light transmittance of the spectrophotometer is not substantially 0, that is, if a translucent or transparent carrier is used, the light is absorbed by the carrier or refracted / dispersed complicatedly. When a colored carrier is used, it is difficult to detect discoloration of the discolored substance, and in any case, the detection sensitivity and stability are reduced.

As the white and opaque carrier, various materials can be used, but those which are stable to the target gas should be selected and widely used as carriers of this type. Silica gel, alumina and the like are preferred. In addition, the method of supporting the color-changing substance on the carrier can be performed by a conventional method that has been conventionally performed, and is not particularly limited.

Further, the content of the color changing substance in the detecting agent is suitably from 1 to 20% by weight, particularly preferably from 2 to 5% by weight. If the amount of the discoloring substance is less than 1%, a sufficient amount of discoloring cannot be obtained, and if it exceeds 20% by weight,
The discoloration sensitivity of the discoloration substance itself becomes low, and the time until discoloration becomes long, and the detection timing may be delayed.

The shape of the filling cylinder and the mounting structure of the detecting portion of the color mark sensor are arbitrary. For example, as described above, the detecting portion 9 and the detecting agent 5 are brought into contact with each other via a transparent material. As shown in FIG. 2, in the same configuration as in FIG. 1, the tip of the optical fiber fixture 11 of the color mark sensor 8 is inserted into the filling tube 3 to
And the detection agent 5 may be brought into direct contact. Furthermore, only the detection agent may be filled in the filling cylinder and used exclusively for detection.

Since a color mark sensor which has been conventionally used for detecting this kind of discoloration can be used as it is, a detailed description thereof will be omitted. As the light source, for example, a halogen lamp or LED can be used, and white light may be used. However, the sensitivity can be improved by using light having an appropriate color tone (wavelength) according to the color change state of the color changing substance. It is possible, for example,
Red light may be used when changing color from blue to black and white to black, and green light may be used when changing color from yellow to red and yellow to purple.

[0022]

Embodiments of the present invention will be described below. Example 1 Bismuth chloride was dissolved in ethanol, and impregnated with opaque white silica gel having a light transmittance of approximately 0 and a particle size of 2 mm measured by a spectrophotometer, followed by vacuum drying at 40 ° C. for 5 hours to obtain silica gel. A white detector carrying bismuth chloride was prepared. The loading amount of bismuth chloride in this detection agent was 3% by weight. This detection agent was packed into a column having an inner diameter of 43 mm and a height of 685 mm to which a color mark sensor was attached so that the height became 100 mm. Note that a red LED was used as a light source.

After purging the column with nitrogen gas,
A test gas containing 100 ppm of arsine in nitrogen gas was allowed to flow at a superficial velocity of 1 cm per second, the discoloration status was visually checked, and a detection test was performed with a color mark sensor. This operation was repeated several times, and the color change of the detection agent could be detected by the color mark sensor almost simultaneously with visually confirming that the detection agent changed color from white to black.

Example 2 The procedure of Example 1 was repeated except that the particle size of the silica gel carrier was 3 mm, and a gas containing 100 ppm of phosphine in nitrogen gas was used as a test gas. As a result, the discoloration could be detected by the color mark sensor substantially simultaneously with the visual confirmation of the discoloration.

Example 3 Copper sulfate was dissolved in water to impregnate white opaque alumina having a particle size of 4 mm, and neutralized by adding ammonia water and an aqueous solution of sodium hydroxide. Vacuum drying was performed to prepare a blue detector having 4% by weight of copper hydroxide supported on an alumina carrier. This detector was packed in the same column as in Example 1 so as to have a height of 100 mm, and a test was performed in the same manner as in Example 1 using a test gas containing 197 ppm of silane in nitrogen gas. As a result, the color change of the detecting agent could be detected by the color mark sensor almost simultaneously with visually confirming that the detecting agent changed to black.

Example 4 The procedure of Example 3 was repeated except that the particle size of alumina as a carrier was 2 mm, and a gas containing 200 ppm of dichlorosilane in nitrogen gas was used as a test gas. as a result,
Almost at the same time as visually confirming the discoloration, the discoloration could be detected by the color mark sensor.

Example 5 Cresol Red was dissolved in hot water, adjusted to pH 8 or more with an aqueous sodium hydroxide solution, impregnated with opaque white silica gel having a particle size of 4 mm, and dried in vacuo at 50 ° C. for 5 hours to obtain silica gel. A yellow detection agent carrying 3% by weight of cresol red was prepared. A test was performed in the same manner as in Example 1 using a green LED as a light source and a test gas containing 98 ppm of hydrogen chloride in nitrogen gas. As a result, the discoloration of the detecting agent could be detected by the color mark sensor almost simultaneously with visually confirming that the detecting agent changed to red.

Example 6 Bromophenol blue was dissolved in hot water, and the pH was adjusted to 6 with hydrochloric acid.
After the following adjustments, opaque white silica gel having a particle diameter of 2 mm was impregnated and dried under vacuum at 50 ° C. for 5 hours to prepare a yellow detecting agent in which 3% by weight of bromophenol blue was supported on silica gel. A test was performed in the same manner as in Example 1 using a green LED as a light source and a test gas containing 81 ppm of ammonia in nitrogen gas. As a result, the color change of the detection agent could be detected by the color mark sensor almost simultaneously with visually confirming that the detection agent changed to purple.

Comparative Example 1 The procedure of Example 1 was repeated except that a transparent white silica gel was used as a carrier. As a result, there was a case where the color mark sensor could not detect the discoloration even though the discoloration to black could be visually confirmed. The same results were obtained with other detection agents.

Comparative Example 2 The procedure of Example 1 was repeated except that the particle size of the silica gel as the carrier was changed to 5 mm. As a result, as in Comparative Example 1, the color mark sensor sometimes failed to detect discoloration. The same results were obtained with other detection agents.

[0031]

As described above, according to the present invention,
It can reliably detect various harmful components contained in exhaust gas from semiconductor manufacturing factories, etc., and it is possible to check the discoloration of the detection agent, which had conventionally depended on visual inspection, unmanned and constantly, Safety and economy can be greatly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of a detection device that performs a method of detecting a harmful gas by a color mark sensor using the detection agent of the present invention.

FIG. 2 is an explanatory diagram illustrating another example of a detection device.

[Explanation of symbols]

1 ... exhaust gas inlet, 2 ... processing gas outlet, 3 ... filling cylinder,
4 ... Main abatement agent, 5 ... Detection agent, 6 ... Preliminary abatement agent, 7 ... Detection window, 8 ... Color mark sensor, 9 ... Detection unit, 10 ... Detection unit, 11 ... Optical fiber fixture, 12,13 ...
Optical fiber

Continuation of the front page (72) Inventor Bunyo Endo 3054-3 Shimokurosawa, Takane-cho, Kita-Koma-gun, Yamanashi

Claims (2)

[Claims] 1. A detection agent comprising a carrier carrying a color changing substance which changes color upon contact with a gas to be detected, wherein the carrier is a white particle having a particle size in the range of 1 to 4 mm, and a spectrophotometer. An agent for detecting a harmful gas, wherein the light transmittance of the meter is substantially 0. 2. A method of detecting harmful gas by detecting color change of a detecting agent by a color mark sensor provided with an optical fiber, wherein the detecting agent is a white particle having a particle size in a range of 1 to 4 mm, and A method for detecting a harmful gas, comprising using a detection agent in which a color changing substance that changes color upon contact with a detection target gas is carried on a carrier having a light transmittance of substantially 0 by a spectrophotometer.