JPH0796135A - Ozone decomposing device - Google Patents

Abstract

PURPOSE:To quantitatively determine the deterioration of a packing by providing a means for detecting the temp. of the heated packing at a part of an ozone decomposing device and monitoring the amt. of heat generated from the ozone decomposition reaction. CONSTITUTION:The temp. of glass wool 3 is detected by a temp. sensor 9, and the temp. of active carbon 4 is detected by temp. sensors 10 and 11. The temp. of the active carbon 4 is kept slightly higher than the temp. of the glass wool 3 (an exothermic reaction does not occur) by the heat of formation of the exothermic ozone decomposition reaction in a part of the active carbon 4, the heat of oxidation reaction of the active carbon itself, etc. Namely, the output differs between the sensor 9 on the reference side and the sensors 10 and 11 on the active carbon side. However, the exothermic reaction is weakened when the ozone decomposition capacity of the active carbon 4 is reduced, hence the amt. of generated heat is decreased, and the output difference between the sensor 9 and sensors 10 and 11 is reduced. Accordingly, the temp. difference is detected and amplified by an amplifier, the difference is indicated on a deterioration degree indicator, and the deterioration state is quantitatively grasped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device utilizing high concentration ozone, for example, a chemiluminescence analyzer utilizing ozone having a concentration of several thousands ppm, and semiconductor manufacturing using ozone having a concentration of tens of thousands ppm. The present invention relates to a decomposer for residual ozone gas in a process.

[0002]

2. Description of the Related Art Various methods such as a thermal decomposition method, a chemical cleaning method, an activated carbon method, and a catalyst method are known as methods for decomposing ozone. However, from the viewpoint of decomposition efficiency and life, a metal oxide catalyst is used. It is widely used to fill the inside of a corrosion-resistant container with activated carbon containing, and to decompose ozone by passing a gas containing ozone through this container.

The structure of this ozone decomposing unit is, for example, as shown in FIG. 1, a suitable filter such as glass wool 3 is provided near the gas inlet 2 in a cylindrical aluminum container 1 which has been subjected to anticorrosion treatment. 1 is filled with an ozone decomposing reagent, that is, activated carbon 4 containing a metal oxide catalyst, and is closed by a lid 6 having a gas discharge port 5. In addition, there are some types in which heating element posistors 7 and 8 are provided outside the container to heat glass wool and activated carbon from the outside to remove water and accelerate the decomposition reaction. As a result, the ozone gas introduced from the inlet portion 2 is decomposed into oxygen by the activated carbon 4 and the catalyst contained therein, and is discharged from the outlet 5 as a harmless gas. This ozone decomposition reaction is an exothermic reaction as shown by the following equation, and is accompanied by heat of formation of 150 KJ (kilojoule) per mol of 20 ₃ → 30 ₂ +68 Kcal.

Generally, in a chemiluminescence analyzer using ozone of a concentration of several thousand ppm, this ozone decomposing device is attached to the exit passage of a chemiluminescence reaction chamber to decompose residual ozone gas and release it into the atmosphere. It is supposed to do. However, during long-term use, the decomposition ability of the filler deteriorates due to the effects of SO ₂ gas, etc., and ozone may not be completely decomposed, and some ozone may be discharged into the atmosphere. .

Obviously, ozone leakage is extremely harmful to the human body. For example, the permissible limit in the working environment is 0.1 ppm or less, and the environmental standard for photochemical oxidants whose main component is ozone is According to the Basic Law for Pollution Control, it is specified to be 0.06 ppm or less. Ozone decomposers are designed to meet these standards, but their maintenance and management are extremely important in actual use. In order to determine the deterioration of the ozone decomposer, there is a method of measuring the ozone concentration in the exhaust gas of the decomposer with a measuring device using an ultraviolet absorption method, but there is a drawback that the device becomes extremely large. In other words, it is desirable that the decomposer itself be able to easily determine deterioration, but in the past there was no means for doing so, so experience has been used to estimate deterioration from the time of use and the decomposer should be replaced early or the filler should be refreshed. It was done.

[0006]

In view of the above, the present invention has been made.
This is intended to enable the ozone decomposer itself to quantitatively determine the deterioration of the filler, and to issue a deterioration alarm if necessary.

[0007]

The present invention focuses on the exothermic reaction during the decomposition of ozone, and utilizes the fact that if the decomposition ability of the filler of the ozone decomposer deteriorates, the amount of heat generated by the decomposition reaction decreases. However, the deterioration of the ozone decomposer is quantitatively measured by detecting and monitoring the decrease in the calorific value.

[0008]

[Function] In a part of the container containing the filler for ozone decomposition,
By attaching one or more temperature sensors or by adding a function to detect an abnormal decrease in the calorific value, the abnormality of the ozone decomposition exothermic reaction can be monitored and the degree of deterioration can be displayed or the deterioration can reach a predetermined limit. Warn that has reached.

[0009]

1 is a structural diagram of one embodiment of the present invention, in which reference numeral 1
8 are the same as those described in the section of the prior art, so the description thereof will be omitted. In this embodiment, if the introduced ozone gas contains water, the resolution of the filler deteriorates. Therefore, a plurality of heat-generating element posistors are attached to the outside of the container, and an electric current is supplied to the heat-generating element posistor to add 80% of the filler. Heat to a constant temperature of about ℃,
It is designed to accelerate the decomposition reaction while removing water.

Reference numerals 9, 10 and 11 denote temperature sensors attached to the container 1, 9 detects the temperature of the glass wool portion 3, and 10 and 11 detect the temperature of the activated carbon 4 portion.

FIG. 2 shows an example of a temperature monitoring circuit using these sensors, 12 is a differential amplifier, and 13 is a differential amplifier.
Is a deterioration indicator, and 14 is a deterioration alarm circuit.

In the structure shown in the figure, when this is operating normally, the temperature of this part is due to the heat generated by the ozone decomposition exothermic reaction in the activated carbon part and the heat caused by the oxidation reaction of the activated carbon. The temperature is maintained slightly higher (several degrees C) than the temperature that does not occur. That is, an output difference occurs between the reference side temperature sensor 9 and the activated carbon side temperature sensors 10 and 11.

However, when the ozone decomposing ability of the activated carbon is deteriorated, the exothermic reaction is naturally weakened so that the calorific value is reduced and the outputs of the temperature sensors 10 and 11 become the same level as the output of 9. That is, the output difference between the sensors 9 and 10, 11 is reduced. Although these temperature differences are small at about 2 to 3 ° C, they can be sufficiently detected by the high-sensitivity temperature sensor. Therefore, the output difference is detected by the differential amplifier 12 as shown in FIG. By displaying it, the deterioration state can be grasped quantitatively. It is also possible to issue an alarm by comparing this output with a predetermined reference level and operating the relay 15 to activate the contact of the alarm device 16 when the output falls below a predetermined level.

In the above embodiments, the exothermic reaction due to ozone decomposition is detected by the temperature sensor or thermistor attached to the container. However, the fillers 3, 4 are made by the heat generating element posistors 7, 8 as illustrated. In the case of heating by heating to a constant temperature, the magnitude of reaction heat can be measured by detecting the change in current consumption for the constant temperature heating. That is, when the ozone decomposition reaction by the activated carbon is normally performed, the current consumption of the posistor 8 becomes slightly smaller than the current of the posistor 7 in the portion where the exothermic reaction does not occur due to the reaction heat. As the deterioration of the activated carbon progresses, heat generation decreases, and as a result, the current consumption of the posistor 8 increases and finally reaches the same level as the current consumption of the posistor 7. Therefore, the degree of deterioration can be measured in the same manner as described above by detecting the change in the current of the heating element 8 or the difference between the currents of the heating elements 7 and 8.

[0015]

As described above, according to the present invention, the deterioration of the filler can be continuously monitored by simply adding a simple structure to the ozone decomposing unit itself, so that the replacement and maintenance of the ozone decomposing unit can be performed with good timing. In addition to the above, the ozone decomposing unit can be automatically replaced by using the deterioration signal.

In addition, it is possible to completely prevent accidental discharge of residual ozone, and the like, which brings excellent effects in terms of safety and environmental protection.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of an embodiment of an ozone decomposer of the present invention.

FIG. 2 is an electric circuit diagram for detecting and monitoring a heat generation state when ozone is decomposed.

[Explanation of symbols]

1 ... Main container of ozone decomposer 3 ... Glass wool 4 ... Activated carbon (catalyst containing) 7, 8 ... Heating element 9, 10, 11 ... Temperature sensor (or thermistor) 13 ... Degradation indicator 14 ... Degradation alarm circuit

Claims (1)

[Claims] 1. A part of a container containing a filler such as activated carbon containing a catalyst for decomposing ozone is provided with means for detecting the exothermic temperature of the filler to monitor the amount of heat generated by the ozone decomposing reaction. The ozonolysis device is characterized in that the deterioration of the filler is judged by doing so.