JP2005231977A - Control method for ozone generator in ozone fumigation system and ozone generator using the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ozone concentration control method that controls the ozone concentration variation due to the change of a temperature and a humidity more accurately so that the remaining value of ozone becomes not more than a safe value (not to affect human body) and that conducts the effective ozone fumigation while safely retaining the ozone concentration into the safe range to human body after fumigation. <P>SOLUTION: The control method for the ozone generator in the ozone fumigation system comprises using a multi-variate self-regressive model for analyzing chronological data of the ozone concentration, calculating the power contribution and impulse response(closed system) of the ozone concentration, the temperature and the humidity from the analysis, setting the standard time of the ozone concentration variation from the impulse response (closed system) of the ozone concentration, creating a state model of the ozone concentration from the values of the power contribution and the impulse response, calculating the estimation time of the ozone concentration variation from the corrected standard time of the ozone concentration variation, setting the amount of ozone generation (or generation time) from the estimation time of the ozone concentration variation so that the ozone concentration at the completion of the ozone fumigation becomes the safe range to human body and further rectifying the amount of ozone generation by estimating the change of the temperature and the humidity to control the ozone generation by program control. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ozone fumigation system, and more particularly, to a safe and efficient ozone generation control method corresponding to a set time of ozone fumigation, and an ozone generation control apparatus using the method.

  Conventionally, ozone fumigation systems using UV lamps have been widely used for sterilization of indoor spaces where people always enter and exit, such as food processing plants, kitchens, family restaurants, banquet halls, and sterilization of sealed spaces such as refrigerators. The UV ozone apparatus includes a large business machine and a small personal machine. The former uses the indoor ozone concentration at about 0.5 ppm, and after use, the indoor residual ozone concentration is set to a value that is safe for the human body (0.05 ppm). The small machine is used at a concentration of 0.1 ppm or less. The goal is to do.

Large machines cannot be used when workers are in a fumigating space. Therefore, a large machine has a mechanism in which an ozone lamp and an ozone-less lamp are set in the main body, and the ozone lamp is turned on only at night when no one is present to eject ozone into the room. Although the ozone concentration at the outlet varies depending on the model, it is on the order of several ppm to several tens of ppm. Using a low-concentration ozone gas detection sensor that detects an ozone gas concentration of 0.1 ppm or less, a safety display unit is connected in series to the make contact side circuit that is switched by the contact signal output by this sensor, and an alarm display unit is connected in series to the break contact side circuit. Japanese Laid-Open Patent Publication No. 2001-328802 shows an ozone concentration status display device arranged.
JP 2001-328802 A

  In the large machine, in the daytime when an operator is present, the air is switched to an ozone-less lamp, and air is sucked to sterilize the air in the apparatus. The switching of the lamp is controlled by a timer, and the operation time can be set freely.

  Only small ozone lamps are set on the small aircraft. Since 24-hour continuous operation is standard, the outlet ozone concentration is set as low as 0.2 to 1 ppm so that the indoor concentration does not exceed ppm. Since this UV lamp has a shorter life as the ambient temperature becomes lower, it is not preferable to use it at a room temperature of 10 degrees or less. Also, since the lamp has a short life of about 8 hours with a single blink, frequent blinking is undesirable.

In such a conventional ozone fumigation system, accurate ozone concentration management is not performed. It is thought that the condition of the substance that reacts with ozone is related to the ozone concentration as the environment in the space where ozone fumigation is performed. However, since the reaction of ozone is very unstable and uncertain, Only simple efforts were made. As such a simple ozone concentration management system, the ozone generation amount is switched (2 to 4 steps) by timer control, and the ozone concentration is kept at a certain value or more by an ozone sensor provided in a suitable place in the room. When this exceeds a specified value, ozone generation is cut off. As an example of this, Japanese Patent Laid-Open No. 2001-61460 is shown.
JP 2001-61460 A

  However, such a control method does not accurately correspond to changes in indoor temperature and humidity, and it is possible to accurately control the ozone concentration in response to changes in ozone concentration accompanying changes in temperature and humidity. Not done.

  In general, it is said that the decomposition of ozone is fast when the indoor temperature and humidity are high, and in response to this, equipment has been developed to increase the ozone concentration as the temperature and humidity rise. Many different results are obtained from past measurement data. As an example, there is a phenomenon in which the ozone concentration temporarily suddenly rises when the humidity decreases, and as a result, if the residual ozone concentration after fumigation becomes excessive, it is dangerous for the operator. Therefore, conventionally, in order to prevent the residual ozone concentration from exceeding the safe value and exerting influence on the human body even if such a phenomenon occurs, the ozone concentration is set to be low in advance. As a result, effects such as sterilization and deodorization by ozone fumigation are often insufficient.

  As an example, regarding ozone air cleaners that can effectively control indoor air pollution, scientific knowledge obtained so far can eliminate most indoor air pollutants at ozone concentrations that do not exceed health standards. However, it has been reported that there is evidence that many chemical substances that cause odor cannot be removed effectively, and that the concentration of biological contaminants such as viruses, bacteria, and molds cannot be removed effectively.

Residual ozone concentration that is safe for the human body without taking into account the effects of temperature and humidity (in recent standards, the Japan Medical Environment Ozone Association living zone ozone safe concentration 0.06 ppm, each country's work environment ozone concentration 0.05 ppm) Such a device capable of fumigation with ozone has not yet been obtained. In addition, no data has been found for continuous measurement of temperature, humidity and ozone concentration. The reasons and reasons are as follows.
(1) The measuring instrument that accurately measures the ozone concentration is expensive (2) It cannot be controlled only by the ozone concentration and the amount of ozone generated (3) By analyzing the measurement results of long-term temperature, humidity, and ozone concentration , The data is very difficult to simplify

  Therefore, the present invention controls the ozone concentration more accurately so that the residual value is below a safe value that does not affect the human body due to temperature and humidity changes, and the ozone concentration is stable within the safe range for the human body after fumigation. The purpose of this study is to construct an ozone concentration control method that performs effective ozone fumigation.

The present invention does not cover the detailed part of the chemical reaction of the substance that reacts with ozone as the environment of the predetermined space, but treats the entire chemical reaction as a target of statistical processing and confirms its action in the field experiment. It is a thing. That is, the present invention performs ozone generation control by the following program control.
(1) A multivariate autoregressive model is used to analyze the time series data of ozone concentration, and the power contribution rate and impulse response (closed system) of ozone concentration / temperature / humidity are calculated from the analysis.
(2) Set the reference time of ozone concentration change from the impulse response (closed system) of ozone concentration,
(3) Create a state model of ozone concentration from the power contribution rate and impulse response values,
Calculate the estimated time of ozone concentration change by correcting the standard time of ozone concentration change,
(4) From the estimated time of the ozone concentration change, set the required amount of ozone generated at each time so that the ozone concentration at the end of ozone fumigation is in a safe range for the human body.
(5) Further estimate the amount of ozone generated by estimating changes in temperature and humidity.
Here, “reference time for ozone concentration change” and “estimation time for ozone concentration change” are new concepts newly used in the present invention. That is, the “reference time for ozone concentration change” indicates the time until the ozone concentration falls below the target ozone concentration (0.05 ppm) based on the impulse response (closed system) data of the ozone concentration. The “estimated time” indicates a time obtained by correcting the “reference time of ozone concentration change” using an ozone concentration state model. Correction of the ozone generation amount by estimating changes in temperature and humidity is performed by, for example, trend analysis.

The control flow of the ozone generation amount according to the present invention is as follows.
(1) Set the ozone fumigation conditions (fumigation time, ozone concentration, etc.)
(2) Start ozone fumigation,
(3) Collect time series data of temperature, humidity, ozone concentration,
(4) Analyze time series data (create a state model of ozone concentration from power contribution rate and impulse response values)
(5) Calculate the reference time for concentration change due to impulse response,
(6) The reference time for concentration change is corrected, and the estimated time of concentration change for the ozone concentration after fumigation to be below the safe value is calculated.
(7) Set the end time of ozone generation (or the optimal ozone generation time at present),
(8) Ozone generation is stopped when the end time of ozone generation is reached.

  As shown in FIG. 1, the hardware of the ozone generation control system according to the present invention has numerical values obtained by measuring the residual ozone concentration, temperature and humidity in the ozone fumigation chamber 1 with an ozone concentration meter 2, a temperature and a hygrometer 3, respectively. It is sent to the computer 4, where it is set by the analyzing means described in paragraph 0012, and the corrected ozone concentration reference value is commanded to the ozone generator 5 so that the ozone concentration in the ozone fumigation chamber 1 is kept at the reference value. To control. The ozone concentration meter 2 collects air from a plurality of air intakes 6 in the ozone fumigation chamber 1 and guides it into the concentration meter 2, while the temperature and hygrometer are in one place in the ozone fumigation chamber 1 or the air intake. Measurement is performed by sensors 7 provided in the vicinity of 6.

According to the present invention, the reference value of the ozone generation concentration can be stably obtained by the concept based on a completely new viewpoint, that is, the following two points, instead of the conventional technique such as a combination.
(1) From the result of impulse response (closed system), set the reference time for ozone concentration change, and use it as the reference value for ozone concentration change,
(2) The point which correct | amends the reference value of ozone concentration change using the state model of ozone concentration.

When changes in temperature, humidity, and ozone concentration during ozone fumigation are as shown in FIGS. 2-1, 2-2, and 2-3, respectively. Using the information criterion (AIC) of Koji Akaike described in Non-Patent Document 1, the order of the multivariate autoregressive model (AR model) is determined so that the value is minimized.
Biological Fluctuation and Rhythm: Introduction to Computer Analysis Supervised by Koji Akaike, Takao Wada, Kodansha (November 20, 1997) ISBN / 4061536540

The calculation results are as shown in Table 1, and the order was determined to be 2.

  Next, an analysis using an AR model (order 2) of three variables (temperature, humidity, ozone concentration) is performed. The power contribution ratio indicating the contribution from each variable innovation to the power spectrum of each variable is calculated. As a result of the calculation, as shown in FIG. 3, when the humidity is output, the power contribution ratio affects both the temperature and the ozone concentration with respect to the output of the humidity. It is big.

  In addition, when the temperature is output, the ozone concentration greatly influences the temperature output, but it is understood that the humidity hardly affects.

  It can also be seen that when the ozone concentration is output, both the temperature and humidity have a small effect on the output of the ozone concentration.

  Similarly, when calculating the impulse response (closed system) to the power spectrum of each variable, when the humidity is input, the temperature has a slight effect on the humidity input, but the ozone concentration is It turns out that there is almost no influence.

  In addition, when the temperature is input, it is understood that neither humidity nor ozone concentration has an influence on the temperature input.

  In addition, when the ozone concentration is input, it can be seen that both the temperature and the humidity greatly affect the input of the ozone concentration. However, the effects of both temperature and humidity are weakening with time. Fig. 2-4 shows a graph of ozone concentration change at the end of ozone fumigation, Fig. 2-5 shows a graph of relative power contribution to ozone concentration, and Fig. 2-6 shows an impulse response graph of ozone concentration.

The state model is shown in FIG. 4A based on the result of the power contribution rate and the impulse response (closed system). The thickness of the arrow indicates the magnitude of the influence. Here, the following way of thinking is taken from the result of the impulse response (closed system).
(1) The time variation of ozone concentration relative to the impulse input of ozone concentration represents the natural reaction of ozone in this environment. (2) 0.05 ppm when the impulse input is converted to the measured ozone concentration. The time it takes for the concentration to decay to (the ozone concentration safe for the human body) is the “reference time for concentration change”.
As shown in FIG. 2-6, the “reference time for density change” is about 1 minute.

Next, the following approach is taken from the result of the power contribution rate.
(1) The “reference time for concentration change” is corrected according to the relationship to the ozone concentration (strength of correlation). The result of impulse response (closed system) and the result of power contribution are combined and corrected as follows. (The state model is shown in FIG. 4 (a)).
(2) Taking into account the time delay and indirect effect of the influence on the ozone concentration, calculate the correction by fuzzy processing (fuzzy rule) and calculate the “estimated time of concentration change”.
Specific examples of fuzzy rules include the following.
Fuzzy rule example 1 There is an effect on ozone concentration, a positive correlation, and a slow effect
If the value is small and the value is large, the correction value is positive and small. Fuzzy Rule Example 2 If there is no effect on the ozone concentration, the correction value is large. As shown in Fig. 4 (a), temperature and humidity affect the ozone concentration. The correction coefficient is large. As a result of the state model shown in FIG.

Thus, the time required for the ozone concentration to be 0.05 ppm or less is 1 minute × 4 (correction coefficient) = 4 minutes. Confirmation with the measurement data of FIG. 2-4 is as follows.
A: Ozone generation end time 11 minutes B: Ozone concentration 0.05 ppm time 15 minutes B−A = about 4 minutes

  When the state changes of temperature, humidity, and ozone concentration during ozone fumigation are as shown in FIG. 4-1, FIG. 4-2, and FIG. Using the quantity criterion (AIC), the order of the multivariate autoregressive model (AR model) is determined so that the value is minimized.

The calculation results are as shown in Table 2, and the order was determined to be 5.

  Next, an analysis using an AR model (degree 5) of three variables (temperature, humidity, ozone concentration) is performed. The power contribution ratio indicating the contribution from each variable innovation to the power spectrum of each variable is calculated. As a result of the calculation, it can be seen that when the humidity is output, the power contribution rate affects both the temperature and the ozone concentration on the output of the humidity.

  It can also be seen that when the temperature is output, both humidity and ozone concentration affect the temperature output. In particular, the influence of humidity is large and the influence of ozone concentration is small, but there is an influence of time delay, and a complicated relationship is exhibited.

  In addition, when the ozone concentration is output, as shown in Table 11, it is understood that the humidity affects the output of the ozone concentration, but there is almost no influence of the temperature.

  Similarly, when calculating the impulse response (closed system) to the power spectrum of each variable, it can be seen that when the humidity is input, the impulse response affects both the temperature and the ozone concentration with respect to the humidity input. . Both temperature and ozone concentration have weakened over time.

  In addition, when temperature is input, it can be seen that both humidity and ozone concentration affect temperature input. Both the humidity and ozone concentration show a complicated relationship, including delayed effects.

  In addition, when the ozone concentration is an input, it can be seen that both the temperature and the humidity affect the input of the ozone concentration. Humidity and temperature have a complicated relationship with time lag and positive / negative correlation changes.

The result of the impulse response (closed system) and the result of the power contribution rate are combined to obtain a state model as shown in FIG. In the figure, the size of the arrow indicates the magnitude of the influence.
The “estimation time for density change” is set as follows.
“Reference time of concentration change” = 27 minutes The correction coefficient is calculated as 0.3 based on the influence of temperature, humidity, and ozone concentration.
“Estimated time of density change” = 27 minutes × 0.3 = 8 minutes 6 seconds.

The confirmation by the measurement data in FIG. 4B is as follows.
A: Ozone generation end time 31 minutes B: Ozone concentration time 0.05 ppm Time 39 minutes B−A = about 8 minutes

  The temperature change graph of space example 2 is shown in FIG. 5-1, and the humidity change graph of space example 2 is shown in FIG. Fig. 5-3 shows a graph of changes in ozone concentration accompanying changes in temperature and humidity in Space Example 2. In addition, a graph of changes in ozone concentration at the end of ozone fumigation is shown in Fig. 5-4. A relative power contribution ratio graph with respect to ozone concentration is shown in FIG. Further, an impulse response graph of ozone concentration is shown in FIG.

Other embodiments include the following.
(1) It is also possible to control the ozone concentration by estimating the temperature / humidity trend from the ozone concentration state model and time series data.
(2) It can be performed as a safe (0.05 ppm ozone fumigation) control system for the ozone generator when there is no restriction on ozone fumigation time (24 hours ozone fumigation state).
(3) If a higher ozone concentration can be set, it is possible to increase the amount of ozone generated.
(4) It is possible to measure ozone concentration and control ozone concentration as a comprehensive safety system.

It is a block diagram of the hardware of the ozone fumigation system by this invention. 3 is a temperature change graph of space example 1; 3 is a humidity change graph of a space example 1; It is an ozone density | concentration change graph accompanying the temperature and humidity change of the example 1 of a space. The graph of the ozone concentration change at the end of ozone fumigation is shown. The relative power contribution rate graph with respect to ozone concentration is shown. The impulse response graph of ozone concentration is shown. It is a graph which shows a power contribution rate. Fig. 2-1, 2 and 3 (temperature, humidity, ozone concentration) state model. The state model of FIGS. 3-1, 2, 3 (temperature, humidity, ozone concentration) is shown. 10 is a temperature change graph of space example 2. It is a humidity change graph of the space example 2. It is an ozone density | concentration change graph accompanying the temperature of the example 2, and a humidity change. The graph of the ozone concentration change at the end of ozone fumigation is shown. The relative power contribution rate graph with respect to ozone concentration is shown. The impulse response graph of ozone concentration is shown.

Explanation of symbols

1 Ozone fumigation chamber 2 Ozone concentration meter 3 Temperature and humidity meter 4 Computer 5 Ozone generator 6 Air intake 7 Sensor

Claims (3)

A control method of an ozone generator in an ozone fumigation system, wherein ozone generation is controlled by program control of the following (1) to (5).
(1) A multivariate autoregressive model is used to analyze the time series data of ozone concentration, and the power contribution rate and impulse response (closed system) of ozone concentration / temperature / humidity are calculated from the analysis.
(2) Set the reference time of ozone concentration change from the impulse response (closed system) of ozone concentration,
(3) Create a state model of ozone concentration from the power contribution rate and impulse response value, calculate the estimated time of ozone concentration change by correcting the reference time of ozone concentration change,
(4) Set the ozone generation amount (or generation time) from the estimated time of ozone concentration change so that the ozone concentration at the end of ozone fumigation falls within the safe range for the human body.
(5) Further estimate the amount of ozone generated by estimating changes in temperature and humidity.   The method for controlling an ozone generator according to claim 1, wherein the correction of the amount of ozone generation by estimating changes in temperature and humidity is performed by trend analysis. The ozone generator provided with the control flow of the ozone generation amount of following (1) thru | or (8).
(1) Set the fumigation conditions such as fumigation time and ozone concentration.
(2) Start ozone fumigation,
(3) Collect time series data of temperature, humidity, ozone concentration,
(4) Create a state model of ozone concentration from the power contribution rate and impulse response values, analyze time series data,
(5) Calculate the reference time for concentration change due to impulse response,
(6) A correction is made to the reference time for the concentration change, and an estimated time for the concentration change for the ozone concentration to be below a value safe for the human body is calculated.
(7) Set the end time of ozone generation (or the optimal ozone generation time at present),
(8) Ozone generation is stopped when the end time of ozone generation is reached.

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