JPH09178653A - Measuring method for ozone concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a measuring method in which an ozone concentration inside a room can be measured without being affected by an oxidant taken into the room from the open air by a method wherein the open air is sampled as a reference gas. SOLUTION: A reference gas is introduced into a measuring cell 9 via a reference-gas pipe passage 2 from a reference-gas sampling port 1, a valve 8 is changed over, and a sample gas is introduced into the measuring cell 9 from a sample-gas pipe 6. The reference gas and the sample gas which are passed through the cell 9 are discharged from a discharge pipe 13 by a pump 15. Then, the inside of the cell 9 is irradiated with a light source 10, transmitted light is received by a detector 11, an output from the detector 11 is processed by a computing part 12, and a measurement is performed in the same manner as in conventional cases. At this time, the sampling port 1 is made to protrude to the outside of a room, and the open air is sampled as the reference gas as it is. As a result, a false report and a malfunction due to the influence of a photochemical oxidant which is taken into the room from the open air are eliminated, and an ozone concentration inside the room can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring ozone concentration in a room.

[0002]

2. Description of the Related Art Ozone has excellent oxidizing power, sterilizing power,
Although the deodorizing power is used for the treatment of water and sewage, its concentration adversely affects the human body, environment and equipment. Therefore, in a processing plant using ozone, it is necessary to constantly monitor the ozone concentration in a room (in the present application, the room) where ozone gas may leak such as an ozone generator room.

Conventionally, when the concentration of ozone gas in a room is measured by absorptiometry, a reference gas (gas not containing ozone gas = zero gas) generated by a reference gas generator is flown into a measurement cell, and ultraviolet rays are introduced into the measurement cell. A reference value is obtained by irradiating a light beam such as the above and measuring the amount of transmission. Next, the gas (sample gas) sampled from the chamber to be measured is flown into the measurement cell as it is, and the amount of transmitted ultraviolet rays is measured as described above. The concentration is measured from the relationship between the two outputs thus obtained (Lambert-Beer's law).

By the above method, leakage of ozone gas from the ozone generator, reaction tank, piping, etc. installed in the room is monitored, and the gas concentration is above a certain level (generally 0.06 to 0.1 ppm). When it becomes, an alarm is issued,
The processing plant shuts down.

By the way, the air pollution situation in Japan is severe, and the pollution by photochemical oxidants is particularly serious. A photochemical oxidant is a strong oxidative power that is secondarily generated by the photochemical reaction of primary pollutants mainly composed of nitrogen oxides and hydrocarbons emitted from factories and automobiles when they are exposed to sunlight. It is a substance with a chemical substance, and its main component is ozone.

Photochemical oxidants cause photochemical smog, and at high concentrations, they cause irritation to mucous membranes and affect respiratory organs. Therefore, the environmental standard "1 hour value is 0.06 ppm or less" has been set. If the hourly value is 0.12 ppm or more and it is recognized that the condition will continue due to weather conditions, the prefectural governor, etc. will issue a warning. The number of days for issuing warnings for photochemical oxidants in 1994 has reached 175 days, and warnings are particularly concentrated in the Tokyo metropolitan area and Kinki area (Fig. 1).

Under the above-mentioned environment, indoor ventilation is usually carried out by directly introducing the air into the room through a ventilation port or the like, so that the photochemical oxidant contained in the atmosphere is also taken into the room. . Therefore, ozone, which is the main component of the photochemical oxidant, is also taken in.

It can be seen from FIG. 2 that there is a correlation between the change in the ozone concentration in the atmosphere and the ozone concentration in the measuring chamber.

[0009]

When the ozone concentration is measured by the conventional method, the reference gas is almost completely converted to zero gas through the reference gas generator, but inside the room, the photochemical oxidant generated in the outside air by ventilation is generated. Is directly taken in, there is a gap between the reference gas and the gas concentration of air in the absence of gas leak in the room.

Therefore, the ozone concentration measuring device installed in the room detects ozone contained in the oxidant taken into the room by ventilation, and issues an alarm even if ozone gas is not leaking from the ozone generator or the like. However, there were inconveniences such as the stop of the processing plant. The present invention has been made to eliminate the above drawbacks.

[0011]

In an indoor ozone gas concentration measuring device, the ozone concentration is measured by sampling the atmosphere as a reference gas. The present invention is a method for measuring ozone gas concentration, which is characterized by the above.

Since the atmospheric air is taken in as the reference gas, the ozone concentration in the room can be measured without being affected by the photochemical oxidant taken in from the outside air to cause false alarms or malfunctions.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. An ozone gas concentration measuring device is installed in the room. For example, a) a measurement cell (9) in which a reference gas and a sample gas are flown, and (b) a reference gas pipe (2) having a reference gas sampling port (1) at the beginning and guiding the reference gas to the measurement cell (9) and A sample gas pipe (6) for guiding the sample gas to the measurement cell (9) is provided, and (c) a valve (8) capable of selectively flowing the reference gas and the sample gas is provided in the measurement cell (9). An exhaust pipe (13) for the reference gas or sample gas that has passed through the measurement cell (9) is provided. The discharge pipe (13) is provided with a pump (15) for flowing the reference gas and the sample gas. (E) A light source (10) for irradiating the inside of the measuring cell (9) and a detector (1) for receiving a light beam that has passed through the inside of the measuring cell (9).
1) is provided, and f) an arithmetic unit (12) for processing the output from the detector (11) is provided. A disassembler (14) is installed in the discharge pipe (13) as required.

An ozone concentration measuring device having the above basic structure is installed. At this time, the reference gas sampling port (1) of the reference gas pipe is taken out of the room so that the atmosphere can be directly collected as the reference gas. Therefore, the reference gas generator (7) is unnecessary. The measurement is performed in the same manner as the conventional method.

The sampling of the reference gas will be described below based on the experimental data. In the case of normal ventilation, the photochemical oxidant concentration in the outside air and the concentration in the room affected by it have a correlation as described above (Fig. 2), but depending on various conditions such as the frequency of ventilation and the use of a ventilation fan. The density difference fluctuates (FIGS. 3 and 4).

Further, when the outside air is sampled, if the reference gas intake port of the reference gas sampling pipe is simply taken out of the room, the fluctuation range of the concentration difference tends to become large due to the influence of the wind direction and the like.

Therefore, in order to stabilize the fluctuation of the photochemical oxidant concentration in the atmosphere and the concentration in the room affected by it, a) the reference gas sampling port (1) is the outside air inlet of the ventilation device (4) such as a ventilation fan. It is suitable to dispose in the vicinity or in a place where the wind direction is constant, such as in the duct (5) of the ventilation device. By doing this, the concentration of the reference gas
It is possible to approach the indoor concentration affected by the oxidant, which is optimum as the reference gas. B) The measurement environment is stabilized by selecting the ventilation frequency with reference to the measurement results (FIGS. 3 and 4). The present invention can be more effectively implemented by considering the above conditions.

[0018]

Industrial Applicability The ozone concentration in the room and the ozone leak can be monitored without being affected by the oxidant taken in from the outside air, and the ozone contained in the oxidant taken in the room can be detected. It is possible to prevent false alarms, malfunctions, etc.

[Brief description of the drawings]

[Fig. 1] Number of postponement days of issuance of warnings, etc. for each prefecture in 1994

[Figure 2] Relationship between ozone concentration in ozone generator room and atmospheric oxidant concentration

[Fig. 3] Concentration difference between ozone and atmospheric oxidant in the measurement room when ventilation is performed three times per hour

[Fig. 4] Concentration difference due to ventilation frequency per hour

FIG. 5: Conventional ozone gas concentration measuring device

FIG. 6 shows an embodiment of the present invention.

FIG. 7 is an embodiment of the present invention in which a reference gas sampling port is arranged near the outside airflow inlet.

FIG. 8 is an embodiment of the present invention in which a reference gas sampling port is provided in a duct.

[Explanation of symbols]

 1 Reference Gas Sampling Port 2 Reference Gas Pipeline 3 Ozone Concentration Measuring Device 4 Ventilation Device 5 Duct 6 Sample Gas Pipe 7 Reference Gas Generation Device 8 Valve 9 Measuring Cell 10 Light Source 11 Detector 12 Computational Section 13 Discharge Pipe 14 Decomposer 15 Pump

Claims (3)

[Claims] 1. A method for measuring ozone concentration, characterized in that in the measurement of ozone concentration in a room, air is sampled as a reference gas. 2. A measurement cell in which a reference gas and a sample gas are caused to flow, a reference gas pipe having a reference gas sampling port at its starting end for guiding the reference gas to the measurement cell, and a sample for guiding the sample gas to the measurement cell. A gas pipe, a valve capable of switching a reference gas and a sample gas to flow in the measurement cell, a reference gas or sample gas discharge pipe having a pump and communicating with the measurement cell, and a light beam in the measurement cell. In an ozone concentration measuring device provided with a light source for irradiating, a detector for receiving a light beam that has passed through the measuring cell, and an arithmetic unit for processing the output from the detector, a ventilation device is provided for the chamber to be measured, The ozone concentration measuring device according to claim 1, wherein the gas sampling port is arranged near an outside airflow inlet of the ventilation device in the room. 3. The ozone concentration measuring device according to claim 2, wherein a ventilation device is provided in the chamber for measurement, and the reference gas sampling port is provided in the duct of the ventilation device.